+++ /dev/null
-This is doc/cpp.info, produced by makeinfo version 4.5 from
-doc/cpp.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* Cpp: (cpp). The GNU C preprocessor.
-END-INFO-DIR-ENTRY
-
-\1f
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-cpp.info-4: 142535
-cpp.info-5: 190066
-\1f
-Tag Table:
-(Indirect)
-Node: Top\7f191
-Node: Overview\7f2796
-Node: Initial processing\7f5164
-Node: Tokenization\7f11621
-Ref: Tokenization-Footnote-1\7f18792
-Node: The preprocessing language\7f18903
-Node: Header Files\7f21776
-Node: Include Syntax\7f23654
-Node: Include Operation\7f25156
-Node: Search Path\7f27052
-Node: Once-Only Headers\7f30129
-Node: Computed Includes\7f31783
-Node: Wrapper Headers\7f34922
-Node: System Headers\7f37341
-Node: Macros\7f39386
-Node: Object-like Macros\7f40486
-Node: Function-like Macros\7f44072
-Node: Macro Arguments\7f45682
-Node: Stringification\7f49827
-Node: Concatenation\7f53028
-Node: Variadic Macros\7f56142
-Node: Predefined Macros\7f60932
-Node: Standard Predefined Macros\7f61515
-Node: Common Predefined Macros\7f66795
-Node: System-specific Predefined Macros\7f73375
-Node: C++ Named Operators\7f75387
-Node: Undefining and Redefining Macros\7f76342
-Node: Macro Pitfalls\7f78420
-Node: Misnesting\7f78945
-Node: Operator Precedence Problems\7f80046
-Node: Swallowing the Semicolon\7f81901
-Node: Duplication of Side Effects\7f83913
-Node: Self-Referential Macros\7f86085
-Node: Argument Prescan\7f88495
-Node: Newlines in Arguments\7f92238
-Node: Conditionals\7f93183
-Node: Conditional Uses\7f95012
-Node: Conditional Syntax\7f96365
-Node: Ifdef\7f96680
-Node: If\7f99846
-Node: Defined\7f102259
-Node: Else\7f103532
-Node: Elif\7f104093
-Node: Deleted Code\7f105373
-Node: Diagnostics\7f106615
-Node: Line Control\7f108232
-Node: Pragmas\7f112039
-Node: Other Directives\7f116308
-Node: Preprocessor Output\7f117502
-Node: Traditional Mode\7f120702
-Node: Implementation Details\7f126281
-Node: Implementation-defined behavior\7f126903
-Node: Implementation limits\7f129176
-Node: Obsolete Features\7f131883
-Node: Assertions\7f132370
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-Node: Differences from previous versions\7f138023
-Node: Invocation\7f142535
-Ref: -MF\7f149854
-Node: Environment Variables\7f162264
-Ref: DEPENDENCIES_OUTPUT\7f163914
-Node: GNU Free Documentation License\7f164954
-Node: Option Index\7f184852
-Node: Index of Directives\7f188319
-Node: Concept Index\7f190066
-\1f
-End Tag Table
+++ /dev/null
-This is doc/cpp.info, produced by makeinfo version 4.5 from
-doc/cpp.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* Cpp: (cpp). The GNU C preprocessor.
-END-INFO-DIR-ENTRY
-
-\1f
-File: cpp.info, Node: Top, Next: Overview, Up: (dir)
-
-
-
- The C preprocessor implements the macro language used to transform C,
-C++, and Objective-C programs before they are compiled. It can also be
-useful on its own.
-
-* Menu:
-
-* Overview::
-* Header Files::
-* Macros::
-* Conditionals::
-* Diagnostics::
-* Line Control::
-* Pragmas::
-* Other Directives::
-* Preprocessor Output::
-* Traditional Mode::
-* Implementation Details::
-* Invocation::
-* Environment Variables::
-* GNU Free Documentation License::
-* Option Index::
-* Index of Directives::
-* Concept Index::
-
- --- The Detailed Node Listing ---
-
-Overview
-
-* Initial processing::
-* Tokenization::
-* The preprocessing language::
-
-Header Files
-
-* Include Syntax::
-* Include Operation::
-* Search Path::
-* Once-Only Headers::
-* Computed Includes::
-* Wrapper Headers::
-* System Headers::
-
-Macros
-
-* Object-like Macros::
-* Function-like Macros::
-* Macro Arguments::
-* Stringification::
-* Concatenation::
-* Variadic Macros::
-* Predefined Macros::
-* Undefining and Redefining Macros::
-* Macro Pitfalls::
-
-Predefined Macros
-
-* Standard Predefined Macros::
-* Common Predefined Macros::
-* System-specific Predefined Macros::
-* C++ Named Operators::
-
-Macro Pitfalls
-
-* Misnesting::
-* Operator Precedence Problems::
-* Swallowing the Semicolon::
-* Duplication of Side Effects::
-* Self-Referential Macros::
-* Argument Prescan::
-* Newlines in Arguments::
-
-Conditionals
-
-* Conditional Uses::
-* Conditional Syntax::
-* Deleted Code::
-
-Conditional Syntax
-
-* Ifdef::
-* If::
-* Defined::
-* Else::
-* Elif::
-
-Implementation Details
-
-* Implementation-defined behavior::
-* Implementation limits::
-* Obsolete Features::
-* Differences from previous versions::
-
-Obsolete Features
-
-* Assertions::
-* Obsolete once-only headers::
-* Miscellaneous obsolete features::
-
- Copyright (C) 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
-1998, 1999, 2000, 2001 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation. A copy of
-the license is included in the section entitled "GNU Free Documentation
-License".
-
- This manual contains no Invariant Sections. The Front-Cover Texts
-are (a) (see below), and the Back-Cover Texts are (b) (see below).
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise funds
-for GNU development.
-
-\1f
-File: cpp.info, Node: Overview, Next: Header Files, Prev: Top, Up: Top
-
-Overview
-********
-
- The C preprocessor, often known as "cpp", is a "macro processor"
-that is used automatically by the C compiler to transform your program
-before compilation. It is called a macro processor because it allows
-you to define "macros", which are brief abbreviations for longer
-constructs.
-
- The C preprocessor is intended to be used only with C, C++, and
-Objective-C source code. In the past, it has been abused as a general
-text processor. It will choke on input which does not obey C's lexical
-rules. For example, apostrophes will be interpreted as the beginning of
-character constants, and cause errors. Also, you cannot rely on it
-preserving characteristics of the input which are not significant to
-C-family languages. If a Makefile is preprocessed, all the hard tabs
-will be removed, and the Makefile will not work.
-
- Having said that, you can often get away with using cpp on things
-which are not C. Other Algol-ish programming languages are often safe
-(Pascal, Ada, etc.) So is assembly, with caution. `-traditional' mode
-preserves more white space, and is otherwise more permissive. Many of
-the problems can be avoided by writing C or C++ style comments instead
-of native language comments, and keeping macros simple.
-
- Wherever possible, you should use a preprocessor geared to the
-language you are writing in. Modern versions of the GNU assembler have
-macro facilities. Most high level programming languages have their own
-conditional compilation and inclusion mechanism. If all else fails,
-try a true general text processor, such as GNU M4.
-
- C preprocessors vary in some details. This manual discusses the GNU
-C preprocessor, which provides a small superset of the features of ISO
-Standard C. In its default mode, the GNU C preprocessor does not do a
-few things required by the standard. These are features which are
-rarely, if ever, used, and may cause surprising changes to the meaning
-of a program which does not expect them. To get strict ISO Standard C,
-you should use the `-std=c89' or `-std=c99' options, depending on which
-version of the standard you want. To get all the mandatory
-diagnostics, you must also use `-pedantic'. *Note Invocation::.
-
-* Menu:
-
-* Initial processing::
-* Tokenization::
-* The preprocessing language::
-
-\1f
-File: cpp.info, Node: Initial processing, Next: Tokenization, Up: Overview
-
-Initial processing
-==================
-
- The preprocessor performs a series of textual transformations on its
-input. These happen before all other processing. Conceptually, they
-happen in a rigid order, and the entire file is run through each
-transformation before the next one begins. GNU CPP actually does them
-all at once, for performance reasons. These transformations correspond
-roughly to the first three "phases of translation" described in the C
-standard.
-
- 1. The input file is read into memory and broken into lines.
-
- GNU CPP expects its input to be a text file, that is, an
- unstructured stream of ASCII characters, with some characters
- indicating the end of a line of text. Extended ASCII character
- sets, such as ISO Latin-1 or Unicode encoded in UTF-8, are also
- acceptable. Character sets that are not strict supersets of
- seven-bit ASCII will not work. We plan to add complete support
- for international character sets in a future release.
-
- Different systems use different conventions to indicate the end of
- a line. GCC accepts the ASCII control sequences `LF', `CR LF',
- `CR', and `LF CR' as end-of-line markers. The first three are the
- canonical sequences used by Unix, DOS and VMS, and the classic Mac
- OS (before OSX) respectively. You may therefore safely copy
- source code written on any of those systems to a different one and
- use it without conversion. (GCC may lose track of the current
- line number if a file doesn't consistently use one convention, as
- sometimes happens when it is edited on computers with different
- conventions that share a network file system.) `LF CR' is
- included because it has been reported as an end-of-line marker
- under exotic conditions.
-
- If the last line of any input file lacks an end-of-line marker,
- the end of the file is considered to implicitly supply one. The C
- standard says that this condition provokes undefined behavior, so
- GCC will emit a warning message.
-
- 2. If trigraphs are enabled, they are replaced by their corresponding
- single characters.
-
- These are nine three-character sequences, all starting with `??',
- that are defined by ISO C to stand for single characters. They
- permit obsolete systems that lack some of C's punctuation to use
- C. For example, `??/' stands for `\', so '??/n' is a character
- constant for a newline. By default, GCC ignores trigraphs, but if
- you request a strictly conforming mode with the `-std' option, then
- it converts them.
-
- Trigraphs are not popular and many compilers implement them
- incorrectly. Portable code should not rely on trigraphs being
- either converted or ignored. If you use the `-Wall' or
- `-Wtrigraphs' options, GCC will warn you when a trigraph would
- change the meaning of your program if it were converted.
-
- In a string constant, you can prevent a sequence of question marks
- from being confused with a trigraph by inserting a backslash
- between the question marks. "(??\?)" is the string `(???)', not
- `(?]'. Traditional C compilers do not recognize this idiom.
-
- The nine trigraphs and their replacements are
-
- Trigraph: ??( ??) ??< ??> ??= ??/ ??' ??! ??-
- Replacement: [ ] { } # \ ^ | ~
-
- 3. Continued lines are merged into one long line.
-
- A continued line is a line which ends with a backslash, `\'. The
- backslash is removed and the following line is joined with the
- current one. No space is inserted, so you may split a line
- anywhere, even in the middle of a word. (It is generally more
- readable to split lines only at white space.)
-
- The trailing backslash on a continued line is commonly referred to
- as a "backslash-newline".
-
- If there is white space between a backslash and the end of a line,
- that is still a continued line. However, as this is usually the
- result of an editing mistake, and many compilers will not accept
- it as a continued line, GCC will warn you about it.
-
- 4. All comments are replaced with single spaces.
-
- There are two kinds of comments. "Block comments" begin with `/*'
- and continue until the next `*/'. Block comments do not nest:
-
- /* this is /* one comment */ text outside comment
-
- "Line comments" begin with `//' and continue to the end of the
- current line. Line comments do not nest either, but it does not
- matter, because they would end in the same place anyway.
-
- // this is // one comment
- text outside comment
-
- It is safe to put line comments inside block comments, or vice versa.
-
- /* block comment
- // contains line comment
- yet more comment
- */ outside comment
-
- // line comment /* contains block comment */
-
- But beware of commenting out one end of a block comment with a line
-comment.
-
- // l.c. /* block comment begins
- oops! this isn't a comment anymore */
-
- Comments are not recognized within string literals. "/* blah */" is
-the string constant `/* blah */', not an empty string.
-
- Line comments are not in the 1989 edition of the C standard, but they
-are recognized by GCC as an extension. In C++ and in the 1999 edition
-of the C standard, they are an official part of the language.
-
- Since these transformations happen before all other processing, you
-can split a line mechanically with backslash-newline anywhere. You can
-comment out the end of a line. You can continue a line comment onto the
-next line with backslash-newline. You can even split `/*', `*/', and
-`//' onto multiple lines with backslash-newline. For example:
-
- /\
- *
- */ # /*
- */ defi\
- ne FO\
- O 10\
- 20
-
-is equivalent to `#define FOO 1020'. All these tricks are extremely
-confusing and should not be used in code intended to be readable.
-
- There is no way to prevent a backslash at the end of a line from
-being interpreted as a backslash-newline.
-
- "foo\\
- bar"
-
-is equivalent to `"foo\bar"', not to `"foo\\bar"'. To avoid having to
-worry about this, do not use the deprecated GNU extension which permits
-multi-line strings. Instead, use string literal concatenation:
-
- "foo\\"
- "bar"
-
-Your program will be more portable this way, too.
-
-\1f
-File: cpp.info, Node: Tokenization, Next: The preprocessing language, Prev: Initial processing, Up: Overview
-
-Tokenization
-============
-
- After the textual transformations are finished, the input file is
-converted into a sequence of "preprocessing tokens". These mostly
-correspond to the syntactic tokens used by the C compiler, but there are
-a few differences. White space separates tokens; it is not itself a
-token of any kind. Tokens do not have to be separated by white space,
-but it is often necessary to avoid ambiguities.
-
- When faced with a sequence of characters that has more than one
-possible tokenization, the preprocessor is greedy. It always makes
-each token, starting from the left, as big as possible before moving on
-to the next token. For instance, `a+++++b' is interpreted as
-`a ++ ++ + b', not as `a ++ + ++ b', even though the latter
-tokenization could be part of a valid C program and the former could
-not.
-
- Once the input file is broken into tokens, the token boundaries never
-change, except when the `##' preprocessing operator is used to paste
-tokens together. *Note Concatenation::. For example,
-
- #define foo() bar
- foo()baz
- ==> bar baz
- _not_
- ==> barbaz
-
- The compiler does not re-tokenize the preprocessor's output. Each
-preprocessing token becomes one compiler token.
-
- Preprocessing tokens fall into five broad classes: identifiers,
-preprocessing numbers, string literals, punctuators, and other. An
-"identifier" is the same as an identifier in C: any sequence of
-letters, digits, or underscores, which begins with a letter or
-underscore. Keywords of C have no significance to the preprocessor;
-they are ordinary identifiers. You can define a macro whose name is a
-keyword, for instance. The only identifier which can be considered a
-preprocessing keyword is `defined'. *Note Defined::.
-
- This is mostly true of other languages which use the C preprocessor.
-However, a few of the keywords of C++ are significant even in the
-preprocessor. *Note C++ Named Operators::.
-
- In the 1999 C standard, identifiers may contain letters which are not
-part of the "basic source character set," at the implementation's
-discretion (such as accented Latin letters, Greek letters, or Chinese
-ideograms). This may be done with an extended character set, or the
-`\u' and `\U' escape sequences. GCC does not presently implement
-either feature in the preprocessor or the compiler.
-
- As an extension, GCC treats `$' as a letter. This is for
-compatibility with some systems, such as VMS, where `$' is commonly
-used in system-defined function and object names. `$' is not a letter
-in strictly conforming mode, or if you specify the `-$' option. *Note
-Invocation::.
-
- A "preprocessing number" has a rather bizarre definition. The
-category includes all the normal integer and floating point constants
-one expects of C, but also a number of other things one might not
-initially recognize as a number. Formally, preprocessing numbers begin
-with an optional period, a required decimal digit, and then continue
-with any sequence of letters, digits, underscores, periods, and
-exponents. Exponents are the two-character sequences `e+', `e-', `E+',
-`E-', `p+', `p-', `P+', and `P-'. (The exponents that begin with `p'
-or `P' are new to C99. They are used for hexadecimal floating-point
-constants.)
-
- The purpose of this unusual definition is to isolate the preprocessor
-from the full complexity of numeric constants. It does not have to
-distinguish between lexically valid and invalid floating-point numbers,
-which is complicated. The definition also permits you to split an
-identifier at any position and get exactly two tokens, which can then be
-pasted back together with the `##' operator.
-
- It's possible for preprocessing numbers to cause programs to be
-misinterpreted. For example, `0xE+12' is a preprocessing number which
-does not translate to any valid numeric constant, therefore a syntax
-error. It does not mean `0xE + 12', which is what you might have
-intended.
-
- "String literals" are string constants, character constants, and
-header file names (the argument of `#include').(1) String constants
-and character constants are straightforward: "..." or '...'. In either
-case embedded quotes should be escaped with a backslash: '\'' is the
-character constant for `''. There is no limit on the length of a
-character constant, but the value of a character constant that contains
-more than one character is implementation-defined. *Note
-Implementation Details::.
-
- Header file names either look like string constants, "...", or are
-written with angle brackets instead, <...>. In either case, backslash
-is an ordinary character. There is no way to escape the closing quote
-or angle bracket. The preprocessor looks for the header file in
-different places depending on which form you use. *Note Include
-Operation::.
-
- In standard C, no string literal may extend past the end of a line.
-GNU CPP accepts multi-line string constants, but not multi-line
-character constants or header file names. This extension is deprecated
-and will be removed in GCC 3.1. You may use continued lines instead,
-or string constant concatenation. *Note Differences from previous
-versions::.
-
- "Punctuators" are all the usual bits of punctuation which are
-meaningful to C and C++. All but three of the punctuation characters in
-ASCII are C punctuators. The exceptions are `@', `$', and ``'. In
-addition, all the two- and three-character operators are punctuators.
-There are also six "digraphs", which the C++ standard calls
-"alternative tokens", which are merely alternate ways to spell other
-punctuators. This is a second attempt to work around missing
-punctuation in obsolete systems. It has no negative side effects,
-unlike trigraphs, but does not cover as much ground. The digraphs and
-their corresponding normal punctuators are:
-
- Digraph: <% %> <: :> %: %:%:
- Punctuator: { } [ ] # ##
-
- Any other single character is considered "other." It is passed on to
-the preprocessor's output unmolested. The C compiler will almost
-certainly reject source code containing "other" tokens. In ASCII, the
-only other characters are `@', `$', ``', and control characters other
-than NUL (all bits zero). (Note that `$' is normally considered a
-letter.) All characters with the high bit set (numeric range
-0x7F-0xFF) are also "other" in the present implementation. This will
-change when proper support for international character sets is added to
-GCC.
-
- NUL is a special case because of the high probability that its
-appearance is accidental, and because it may be invisible to the user
-(many terminals do not display NUL at all). Within comments, NULs are
-silently ignored, just as any other character would be. In running
-text, NUL is considered white space. For example, these two directives
-have the same meaning.
-
- #define X^@1
- #define X 1
-
-(where `^@' is ASCII NUL). Within string or character constants, NULs
-are preserved. In the latter two cases the preprocessor emits a
-warning message.
-
- ---------- Footnotes ----------
-
- (1) The C standard uses the term "string literal" to refer only to
-what we are calling "string constants".
-
-\1f
-File: cpp.info, Node: The preprocessing language, Prev: Tokenization, Up: Overview
-
-The preprocessing language
-==========================
-
- After tokenization, the stream of tokens may simply be passed
-straight to the compiler's parser. However, if it contains any
-operations in the "preprocessing language", it will be transformed
-first. This stage corresponds roughly to the standard's "translation
-phase 4" and is what most people think of as the preprocessor's job.
-
- The preprocessing language consists of "directives" to be executed
-and "macros" to be expanded. Its primary capabilities are:
-
- * Inclusion of header files. These are files of declarations that
- can be substituted into your program.
-
- * Macro expansion. You can define "macros", which are abbreviations
- for arbitrary fragments of C code. The preprocessor will replace
- the macros with their definitions throughout the program. Some
- macros are automatically defined for you.
-
- * Conditional compilation. You can include or exclude parts of the
- program according to various conditions.
-
- * Line control. If you use a program to combine or rearrange source
- files into an intermediate file which is then compiled, you can
- use line control to inform the compiler where each source line
- originally came from.
-
- * Diagnostics. You can detect problems at compile time and issue
- errors or warnings.
-
- There are a few more, less useful, features.
-
- Except for expansion of predefined macros, all these operations are
-triggered with "preprocessing directives". Preprocessing directives
-are lines in your program that start with `#'. Whitespace is allowed
-before and after the `#'. The `#' is followed by an identifier, the
-"directive name". It specifies the operation to perform. Directives
-are commonly referred to as `#NAME' where NAME is the directive name.
-For example, `#define' is the directive that defines a macro.
-
- The `#' which begins a directive cannot come from a macro expansion.
-Also, the directive name is not macro expanded. Thus, if `foo' is
-defined as a macro expanding to `define', that does not make `#foo' a
-valid preprocessing directive.
-
- The set of valid directive names is fixed. Programs cannot define
-new preprocessing directives.
-
- Some directives require arguments; these make up the rest of the
-directive line and must be separated from the directive name by
-whitespace. For example, `#define' must be followed by a macro name
-and the intended expansion of the macro.
-
- A preprocessing directive cannot cover more than one line. The line
-may, however, be continued with backslash-newline, or by a block comment
-which extends past the end of the line. In either case, when the
-directive is processed, the continuations have already been merged with
-the first line to make one long line.
-
-\1f
-File: cpp.info, Node: Header Files, Next: Macros, Prev: Overview, Up: Top
-
-Header Files
-************
-
- A header file is a file containing C declarations and macro
-definitions (*note Macros::) to be shared between several source files.
-You request the use of a header file in your program by "including"
-it, with the C preprocessing directive `#include'.
-
- Header files serve two purposes.
-
- * System header files declare the interfaces to parts of the
- operating system. You include them in your program to supply the
- definitions and declarations you need to invoke system calls and
- libraries.
-
- * Your own header files contain declarations for interfaces between
- the source files of your program. Each time you have a group of
- related declarations and macro definitions all or most of which
- are needed in several different source files, it is a good idea to
- create a header file for them.
-
- Including a header file produces the same results as copying the
-header file into each source file that needs it. Such copying would be
-time-consuming and error-prone. With a header file, the related
-declarations appear in only one place. If they need to be changed, they
-can be changed in one place, and programs that include the header file
-will automatically use the new version when next recompiled. The header
-file eliminates the labor of finding and changing all the copies as well
-as the risk that a failure to find one copy will result in
-inconsistencies within a program.
-
- In C, the usual convention is to give header files names that end
-with `.h'. It is most portable to use only letters, digits, dashes, and
-underscores in header file names, and at most one dot.
-
-* Menu:
-
-* Include Syntax::
-* Include Operation::
-* Search Path::
-* Once-Only Headers::
-* Computed Includes::
-* Wrapper Headers::
-* System Headers::
-
-\1f
-File: cpp.info, Node: Include Syntax, Next: Include Operation, Up: Header Files
-
-Include Syntax
-==============
-
- Both user and system header files are included using the
-preprocessing directive `#include'. It has two variants:
-
-`#include <FILE>'
- This variant is used for system header files. It searches for a
- file named FILE in a standard list of system directories. You can
- prepend directories to this list with the `-I' option (*note
- Invocation::).
-
-`#include "FILE"'
- This variant is used for header files of your own program. It
- searches for a file named FILE first in the directory containing
- the current file, then in the same directories used for `<FILE>'.
-
- The argument of `#include', whether delimited with quote marks or
-angle brackets, behaves like a string constant in that comments are not
-recognized, and macro names are not expanded. Thus, `#include <x/*y>'
-specifies inclusion of a system header file named `x/*y'.
-
- However, if backslashes occur within FILE, they are considered
-ordinary text characters, not escape characters. None of the character
-escape sequences appropriate to string constants in C are processed.
-Thus, `#include "x\n\\y"' specifies a filename containing three
-backslashes. (Some systems interpret `\' as a pathname separator. All
-of these also interpret `/' the same way. It is most portable to use
-only `/'.)
-
- It is an error if there is anything (other than comments) on the line
-after the file name.
-
-\1f
-File: cpp.info, Node: Include Operation, Next: Search Path, Prev: Include Syntax, Up: Header Files
-
-Include Operation
-=================
-
- The `#include' directive works by directing the C preprocessor to
-scan the specified file as input before continuing with the rest of the
-current file. The output from the preprocessor contains the output
-already generated, followed by the output resulting from the included
-file, followed by the output that comes from the text after the
-`#include' directive. For example, if you have a header file
-`header.h' as follows,
-
- char *test (void);
-
-and a main program called `program.c' that uses the header file, like
-this,
-
- int x;
- #include "header.h"
-
- int
- main (void)
- {
- puts (test ());
- }
-
-the compiler will see the same token stream as it would if `program.c'
-read
-
- int x;
- char *test (void);
-
- int
- main (void)
- {
- puts (test ());
- }
-
- Included files are not limited to declarations and macro definitions;
-those are merely the typical uses. Any fragment of a C program can be
-included from another file. The include file could even contain the
-beginning of a statement that is concluded in the containing file, or
-the end of a statement that was started in the including file. However,
-a comment or a string or character constant may not start in the
-included file and finish in the including file. An unterminated
-comment, string constant or character constant in an included file is
-considered to end (with an error message) at the end of the file.
-
- To avoid confusion, it is best if header files contain only complete
-syntactic units--function declarations or definitions, type
-declarations, etc.
-
- The line following the `#include' directive is always treated as a
-separate line by the C preprocessor, even if the included file lacks a
-final newline.
-
-\1f
-File: cpp.info, Node: Search Path, Next: Once-Only Headers, Prev: Include Operation, Up: Header Files
-
-Search Path
-===========
-
- GCC looks in several different places for headers. On a normal Unix
-system, if you do not instruct it otherwise, it will look for headers
-requested with `#include <FILE>' in:
-
- /usr/local/include
- /usr/lib/gcc-lib/TARGET/VERSION/include
- /usr/TARGET/include
- /usr/include
-
- For C++ programs, it will also look in `/usr/include/g++-v3', first.
-In the above, TARGET is the canonical name of the system GCC was
-configured to compile code for; often but not always the same as the
-canonical name of the system it runs on. VERSION is the version of GCC
-in use.
-
- You can add to this list with the `-IDIR' command line option. All
-the directories named by `-I' are searched, in left-to-right order,
-_before_ the default directories. The only exception is when `dir' is
-already searched by default. In this case, the option is ignored and
-the search order for system directories remains unchanged.
-
- Duplicate directories are removed from the quote and bracket search
-chains before the two chains are merged to make the final search chain.
-Thus, it is possible for a directory to occur twice in the final search
-chain if it was specified in both the quote and bracket chains.
-
- You can prevent GCC from searching any of the default directories
-with the `-nostdinc' option. This is useful when you are compiling an
-operating system kernel or some other program that does not use the
-standard C library facilities, or the standard C library itself. `-I'
-options are not ignored as described above when `-nostdinc' is in
-effect.
-
- GCC looks for headers requested with `#include "FILE"' first in the
-directory containing the current file, then in the same places it would
-have looked for a header requested with angle brackets. For example,
-if `/usr/include/sys/stat.h' contains `#include "types.h"', GCC looks
-for `types.h' first in `/usr/include/sys', then in its usual search
-path.
-
- `#line' (*note Line Control::) does not change GCC's idea of the
-directory containing the current file.
-
- You may put `-I-' at any point in your list of `-I' options. This
-has two effects. First, directories appearing before the `-I-' in the
-list are searched only for headers requested with quote marks.
-Directories after `-I-' are searched for all headers. Second, the
-directory containing the current file is not searched for anything,
-unless it happens to be one of the directories named by an `-I' switch.
-
- `-I. -I-' is not the same as no `-I' options at all, and does not
-cause the same behavior for `<>' includes that `""' includes get with
-no special options. `-I.' searches the compiler's current working
-directory for header files. That may or may not be the same as the
-directory containing the current file.
-
- If you need to look for headers in a directory named `-', write
-`-I./-'.
-
- There are several more ways to adjust the header search path. They
-are generally less useful. *Note Invocation::.
-
-\1f
-File: cpp.info, Node: Once-Only Headers, Next: Computed Includes, Prev: Search Path, Up: Header Files
-
-Once-Only Headers
-=================
-
- If a header file happens to be included twice, the compiler will
-process its contents twice. This is very likely to cause an error,
-e.g. when the compiler sees the same structure definition twice. Even
-if it does not, it will certainly waste time.
-
- The standard way to prevent this is to enclose the entire real
-contents of the file in a conditional, like this:
-
- /* File foo. */
- #ifndef FILE_FOO_SEEN
- #define FILE_FOO_SEEN
-
- THE ENTIRE FILE
-
- #endif /* !FILE_FOO_SEEN */
-
- This construct is commonly known as a "wrapper #ifndef". When the
-header is included again, the conditional will be false, because
-`FILE_FOO_SEEN' is defined. The preprocessor will skip over the entire
-contents of the file, and the compiler will not see it twice.
-
- GNU CPP optimizes even further. It remembers when a header file has
-a wrapper `#ifndef'. If a subsequent `#include' specifies that header,
-and the macro in the `#ifndef' is still defined, it does not bother to
-rescan the file at all.
-
- You can put comments outside the wrapper. They will not interfere
-with this optimization.
-
- The macro `FILE_FOO_SEEN' is called the "controlling macro" or
-"guard macro". In a user header file, the macro name should not begin
-with `_'. In a system header file, it should begin with `__' to avoid
-conflicts with user programs. In any kind of header file, the macro
-name should contain the name of the file and some additional text, to
-avoid conflicts with other header files.
-
-\1f
-File: cpp.info, Node: Computed Includes, Next: Wrapper Headers, Prev: Once-Only Headers, Up: Header Files
-
-Computed Includes
-=================
-
- Sometimes it is necessary to select one of several different header
-files to be included into your program. They might specify
-configuration parameters to be used on different sorts of operating
-systems, for instance. You could do this with a series of conditionals,
-
- #if SYSTEM_1
- # include "system_1.h"
- #elif SYSTEM_2
- # include "system_2.h"
- #elif SYSTEM_3
- ...
- #endif
-
- That rapidly becomes tedious. Instead, the preprocessor offers the
-ability to use a macro for the header name. This is called a "computed
-include". Instead of writing a header name as the direct argument of
-`#include', you simply put a macro name there instead:
-
- #define SYSTEM_H "system_1.h"
- ...
- #include SYSTEM_H
-
-`SYSTEM_H' will be expanded, and the preprocessor will look for
-`system_1.h' as if the `#include' had been written that way originally.
-`SYSTEM_H' could be defined by your Makefile with a `-D' option.
-
- You must be careful when you define the macro. `#define' saves
-tokens, not text. The preprocessor has no way of knowing that the macro
-will be used as the argument of `#include', so it generates ordinary
-tokens, not a header name. This is unlikely to cause problems if you
-use double-quote includes, which are close enough to string constants.
-If you use angle brackets, however, you may have trouble.
-
- The syntax of a computed include is actually a bit more general than
-the above. If the first non-whitespace character after `#include' is
-not `"' or `<', then the entire line is macro-expanded like running
-text would be.
-
- If the line expands to a single string constant, the contents of that
-string constant are the file to be included. CPP does not re-examine
-the string for embedded quotes, but neither does it process backslash
-escapes in the string. Therefore
-
- #define HEADER "a\"b"
- #include HEADER
-
-looks for a file named `a\"b'. CPP searches for the file according to
-the rules for double-quoted includes.
-
- If the line expands to a token stream beginning with a `<' token and
-including a `>' token, then the tokens between the `<' and the first
-`>' are combined to form the filename to be included. Any whitespace
-between tokens is reduced to a single space; then any space after the
-initial `<' is retained, but a trailing space before the closing `>' is
-ignored. CPP searches for the file according to the rules for
-angle-bracket includes.
-
- In either case, if there are any tokens on the line after the file
-name, an error occurs and the directive is not processed. It is also
-an error if the result of expansion does not match either of the two
-expected forms.
-
- These rules are implementation-defined behavior according to the C
-standard. To minimize the risk of different compilers interpreting your
-computed includes differently, we recommend you use only a single
-object-like macro which expands to a string constant. This will also
-minimize confusion for people reading your program.
-
-\1f
-File: cpp.info, Node: Wrapper Headers, Next: System Headers, Prev: Computed Includes, Up: Header Files
-
-Wrapper Headers
-===============
-
- Sometimes it is necessary to adjust the contents of a system-provided
-header file without editing it directly. GCC's `fixincludes' operation
-does this, for example. One way to do that would be to create a new
-header file with the same name and insert it in the search path before
-the original header. That works fine as long as you're willing to
-replace the old header entirely. But what if you want to refer to the
-old header from the new one?
-
- You cannot simply include the old header with `#include'. That will
-start from the beginning, and find your new header again. If your
-header is not protected from multiple inclusion (*note Once-Only
-Headers::), it will recurse infinitely and cause a fatal error.
-
- You could include the old header with an absolute pathname:
- #include "/usr/include/old-header.h"
-
-This works, but is not clean; should the system headers ever move, you
-would have to edit the new headers to match.
-
- There is no way to solve this problem within the C standard, but you
-can use the GNU extension `#include_next'. It means, "Include the
-_next_ file with this name." This directive works like `#include'
-except in searching for the specified file: it starts searching the
-list of header file directories _after_ the directory in which the
-current file was found.
-
- Suppose you specify `-I /usr/local/include', and the list of
-directories to search also includes `/usr/include'; and suppose both
-directories contain `signal.h'. Ordinary `#include <signal.h>' finds
-the file under `/usr/local/include'. If that file contains
-`#include_next <signal.h>', it starts searching after that directory,
-and finds the file in `/usr/include'.
-
- `#include_next' does not distinguish between `<FILE>' and `"FILE"'
-inclusion, nor does it check that the file you specify has the same
-name as the current file. It simply looks for the file named, starting
-with the directory in the search path after the one where the current
-file was found.
-
- The use of `#include_next' can lead to great confusion. We
-recommend it be used only when there is no other alternative. In
-particular, it should not be used in the headers belonging to a specific
-program; it should be used only to make global corrections along the
-lines of `fixincludes'.
-
-\1f
-File: cpp.info, Node: System Headers, Prev: Wrapper Headers, Up: Header Files
-
-System Headers
-==============
-
- The header files declaring interfaces to the operating system and
-runtime libraries often cannot be written in strictly conforming C.
-Therefore, GCC gives code found in "system headers" special treatment.
-All warnings, other than those generated by `#warning' (*note
-Diagnostics::), are suppressed while GCC is processing a system header.
-Macros defined in a system header are immune to a few warnings
-wherever they are expanded. This immunity is granted on an ad-hoc
-basis, when we find that a warning generates lots of false positives
-because of code in macros defined in system headers.
-
- Normally, only the headers found in specific directories are
-considered system headers. These directories are determined when GCC
-is compiled. There are, however, two ways to make normal headers into
-system headers.
-
- The `-isystem' command line option adds its argument to the list of
-directories to search for headers, just like `-I'. Any headers found
-in that directory will be considered system headers.
-
- All directories named by `-isystem' are searched _after_ all
-directories named by `-I', no matter what their order was on the
-command line. If the same directory is named by both `-I' and
-`-isystem', the `-I' option is ignored. GCC provides an informative
-message when this occurs if `-v' is used.
-
- There is also a directive, `#pragma GCC system_header', which tells
-GCC to consider the rest of the current include file a system header,
-no matter where it was found. Code that comes before the `#pragma' in
-the file will not be affected. `#pragma GCC system_header' has no
-effect in the primary source file.
-
- On very old systems, some of the pre-defined system header
-directories get even more special treatment. GNU C++ considers code in
-headers found in those directories to be surrounded by an `extern "C"'
-block. There is no way to request this behavior with a `#pragma', or
-from the command line.
-
-\1f
-File: cpp.info, Node: Macros, Next: Conditionals, Prev: Header Files, Up: Top
-
-Macros
-******
-
- A "macro" is a fragment of code which has been given a name.
-Whenever the name is used, it is replaced by the contents of the macro.
-There are two kinds of macros. They differ mostly in what they look
-like when they are used. "Object-like" macros resemble data objects
-when used, "function-like" macros resemble function calls.
-
- You may define any valid identifier as a macro, even if it is a C
-keyword. The preprocessor does not know anything about keywords. This
-can be useful if you wish to hide a keyword such as `const' from an
-older compiler that does not understand it. However, the preprocessor
-operator `defined' (*note Defined::) can never be defined as a macro,
-and C++'s named operators (*note C++ Named Operators::) cannot be
-macros when you are compiling C++.
-
-* Menu:
-
-* Object-like Macros::
-* Function-like Macros::
-* Macro Arguments::
-* Stringification::
-* Concatenation::
-* Variadic Macros::
-* Predefined Macros::
-* Undefining and Redefining Macros::
-* Macro Pitfalls::
-
-\1f
-File: cpp.info, Node: Object-like Macros, Next: Function-like Macros, Up: Macros
-
-Object-like Macros
-==================
-
- An "object-like macro" is a simple identifier which will be replaced
-by a code fragment. It is called object-like because it looks like a
-data object in code that uses it. They are most commonly used to give
-symbolic names to numeric constants.
-
- You create macros with the `#define' directive. `#define' is
-followed by the name of the macro and then the token sequence it should
-be an abbreviation for, which is variously referred to as the macro's
-"body", "expansion" or "replacement list". For example,
-
- #define BUFFER_SIZE 1024
-
-defines a macro named `BUFFER_SIZE' as an abbreviation for the token
-`1024'. If somewhere after this `#define' directive there comes a C
-statement of the form
-
- foo = (char *) malloc (BUFFER_SIZE);
-
-then the C preprocessor will recognize and "expand" the macro
-`BUFFER_SIZE'. The C compiler will see the same tokens as it would if
-you had written
-
- foo = (char *) malloc (1024);
-
- By convention, macro names are written in upper case. Programs are
-easier to read when it is possible to tell at a glance which names are
-macros.
-
- The macro's body ends at the end of the `#define' line. You may
-continue the definition onto multiple lines, if necessary, using
-backslash-newline. When the macro is expanded, however, it will all
-come out on one line. For example,
-
- #define NUMBERS 1, \
- 2, \
- 3
- int x[] = { NUMBERS };
- ==> int x[] = { 1, 2, 3 };
-
-The most common visible consequence of this is surprising line numbers
-in error messages.
-
- There is no restriction on what can go in a macro body provided it
-decomposes into valid preprocessing tokens. Parentheses need not
-balance, and the body need not resemble valid C code. (If it does not,
-you may get error messages from the C compiler when you use the macro.)
-
- The C preprocessor scans your program sequentially. Macro
-definitions take effect at the place you write them. Therefore, the
-following input to the C preprocessor
-
- foo = X;
- #define X 4
- bar = X;
-
-produces
-
- foo = X;
- bar = 4;
-
- When the preprocessor expands a macro name, the macro's expansion
-replaces the macro invocation, then the expansion is examined for more
-macros to expand. For example,
-
- #define TABLESIZE BUFSIZE
- #define BUFSIZE 1024
- TABLESIZE
- ==> BUFSIZE
- ==> 1024
-
-`TABLESIZE' is expanded first to produce `BUFSIZE', then that macro is
-expanded to produce the final result, `1024'.
-
- Notice that `BUFSIZE' was not defined when `TABLESIZE' was defined.
-The `#define' for `TABLESIZE' uses exactly the expansion you
-specify--in this case, `BUFSIZE'--and does not check to see whether it
-too contains macro names. Only when you _use_ `TABLESIZE' is the
-result of its expansion scanned for more macro names.
-
- This makes a difference if you change the definition of `BUFSIZE' at
-some point in the source file. `TABLESIZE', defined as shown, will
-always expand using the definition of `BUFSIZE' that is currently in
-effect:
-
- #define BUFSIZE 1020
- #define TABLESIZE BUFSIZE
- #undef BUFSIZE
- #define BUFSIZE 37
-
-Now `TABLESIZE' expands (in two stages) to `37'.
-
- If the expansion of a macro contains its own name, either directly or
-via intermediate macros, it is not expanded again when the expansion is
-examined for more macros. This prevents infinite recursion. *Note
-Self-Referential Macros::, for the precise details.
-
-\1f
-File: cpp.info, Node: Function-like Macros, Next: Macro Arguments, Prev: Object-like Macros, Up: Macros
-
-Function-like Macros
-====================
-
- You can also define macros whose use looks like a function call.
-These are called "function-like macros". To define a function-like
-macro, you use the same `#define' directive, but you put a pair of
-parentheses immediately after the macro name. For example,
-
- #define lang_init() c_init()
- lang_init()
- ==> c_init()
-
- A function-like macro is only expanded if its name appears with a
-pair of parentheses after it. If you write just the name, it is left
-alone. This can be useful when you have a function and a macro of the
-same name, and you wish to use the function sometimes.
-
- extern void foo(void);
- #define foo() /* optimized inline version */
- ...
- foo();
- funcptr = foo;
-
- Here the call to `foo()' will use the macro, but the function
-pointer will get the address of the real function. If the macro were to
-be expanded, it would cause a syntax error.
-
- If you put spaces between the macro name and the parentheses in the
-macro definition, that does not define a function-like macro, it defines
-an object-like macro whose expansion happens to begin with a pair of
-parentheses.
-
- #define lang_init () c_init()
- lang_init()
- ==> () c_init()()
-
- The first two pairs of parentheses in this expansion come from the
-macro. The third is the pair that was originally after the macro
-invocation. Since `lang_init' is an object-like macro, it does not
-consume those parentheses.
-
-\1f
-File: cpp.info, Node: Macro Arguments, Next: Stringification, Prev: Function-like Macros, Up: Macros
-
-Macro Arguments
-===============
-
- Function-like macros can take "arguments", just like true functions.
-To define a macro that uses arguments, you insert "parameters" between
-the pair of parentheses in the macro definition that make the macro
-function-like. The parameters must be valid C identifiers, separated
-by commas and optionally whitespace.
-
- To invoke a macro that takes arguments, you write the name of the
-macro followed by a list of "actual arguments" in parentheses, separated
-by commas. The invocation of the macro need not be restricted to a
-single logical line--it can cross as many lines in the source file as
-you wish. The number of arguments you give must match the number of
-parameters in the macro definition. When the macro is expanded, each
-use of a parameter in its body is replaced by the tokens of the
-corresponding argument. (You need not use all of the parameters in the
-macro body.)
-
- As an example, here is a macro that computes the minimum of two
-numeric values, as it is defined in many C programs, and some uses.
-
- #define min(X, Y) ((X) < (Y) ? (X) : (Y))
- x = min(a, b); ==> x = ((a) < (b) ? (a) : (b));
- y = min(1, 2); ==> y = ((1) < (2) ? (1) : (2));
- z = min(a + 28, *p); ==> z = ((a + 28) < (*p) ? (a + 28) : (*p));
-
-(In this small example you can already see several of the dangers of
-macro arguments. *Note Macro Pitfalls::, for detailed explanations.)
-
- Leading and trailing whitespace in each argument is dropped, and all
-whitespace between the tokens of an argument is reduced to a single
-space. Parentheses within each argument must balance; a comma within
-such parentheses does not end the argument. However, there is no
-requirement for square brackets or braces to balance, and they do not
-prevent a comma from separating arguments. Thus,
-
- macro (array[x = y, x + 1])
-
-passes two arguments to `macro': `array[x = y' and `x + 1]'. If you
-want to supply `array[x = y, x + 1]' as an argument, you can write it
-as `array[(x = y, x + 1)]', which is equivalent C code.
-
- All arguments to a macro are completely macro-expanded before they
-are substituted into the macro body. After substitution, the complete
-text is scanned again for macros to expand, including the arguments.
-This rule may seem strange, but it is carefully designed so you need
-not worry about whether any function call is actually a macro
-invocation. You can run into trouble if you try to be too clever,
-though. *Note Argument Prescan::, for detailed discussion.
-
- For example, `min (min (a, b), c)' is first expanded to
-
- min (((a) < (b) ? (a) : (b)), (c))
-
-and then to
-
- ((((a) < (b) ? (a) : (b))) < (c)
- ? (((a) < (b) ? (a) : (b)))
- : (c))
-
-(Line breaks shown here for clarity would not actually be generated.)
-
- You can leave macro arguments empty; this is not an error to the
-preprocessor (but many macros will then expand to invalid code). You
-cannot leave out arguments entirely; if a macro takes two arguments,
-there must be exactly one comma at the top level of its argument list.
-Here are some silly examples using `min':
-
- min(, b) ==> (( ) < (b) ? ( ) : (b))
- min(a, ) ==> ((a ) < ( ) ? (a ) : ( ))
- min(,) ==> (( ) < ( ) ? ( ) : ( ))
- min((,),) ==> (((,)) < ( ) ? ((,)) : ( ))
-
- min() error--> macro "min" requires 2 arguments, but only 1 given
- min(,,) error--> macro "min" passed 3 arguments, but takes just 2
-
- Whitespace is not a preprocessing token, so if a macro `foo' takes
-one argument, `foo ()' and `foo ( )' both supply it an empty argument.
-Previous GNU preprocessor implementations and documentation were
-incorrect on this point, insisting that a function-like macro that
-takes a single argument be passed a space if an empty argument was
-required.
-
- Macro parameters appearing inside string literals are not replaced by
-their corresponding actual arguments.
-
- #define foo(x) x, "x"
- foo(bar) ==> bar, "x"
-
+++ /dev/null
-This is doc/cpp.info, produced by makeinfo version 4.5 from
-doc/cpp.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* Cpp: (cpp). The GNU C preprocessor.
-END-INFO-DIR-ENTRY
-
-\1f
-File: cpp.info, Node: Stringification, Next: Concatenation, Prev: Macro Arguments, Up: Macros
-
-Stringification
-===============
-
- Sometimes you may want to convert a macro argument into a string
-constant. Parameters are not replaced inside string constants, but you
-can use the `#' preprocessing operator instead. When a macro parameter
-is used with a leading `#', the preprocessor replaces it with the
-literal text of the actual argument, converted to a string constant.
-Unlike normal parameter replacement, the argument is not macro-expanded
-first. This is called "stringification".
-
- There is no way to combine an argument with surrounding text and
-stringify it all together. Instead, you can write a series of adjacent
-string constants and stringified arguments. The preprocessor will
-replace the stringified arguments with string constants. The C
-compiler will then combine all the adjacent string constants into one
-long string.
-
- Here is an example of a macro definition that uses stringification:
-
- #define WARN_IF(EXP) \
- do { if (EXP) \
- fprintf (stderr, "Warning: " #EXP "\n"); } \
- while (0)
- WARN_IF (x == 0);
- ==> do { if (x == 0)
- fprintf (stderr, "Warning: " "x == 0" "\n"); } while (0);
-
-The argument for `EXP' is substituted once, as-is, into the `if'
-statement, and once, stringified, into the argument to `fprintf'. If
-`x' were a macro, it would be expanded in the `if' statement, but not
-in the string.
-
- The `do' and `while (0)' are a kludge to make it possible to write
-`WARN_IF (ARG);', which the resemblance of `WARN_IF' to a function
-would make C programmers want to do; see *Note Swallowing the
-Semicolon::.
-
- Stringification in C involves more than putting double-quote
-characters around the fragment. The preprocessor backslash-escapes the
-quotes surrounding embedded string constants, and all backslashes
-within string and character constants, in order to get a valid C string
-constant with the proper contents. Thus, stringifying `p = "foo\n";'
-results in "p = \"foo\\n\";". However, backslashes that are not inside
-string or character constants are not duplicated: `\n' by itself
-stringifies to "\n".
-
- All leading and trailing whitespace in text being stringified is
-ignored. Any sequence of whitespace in the middle of the text is
-converted to a single space in the stringified result. Comments are
-replaced by whitespace long before stringification happens, so they
-never appear in stringified text.
-
- There is no way to convert a macro argument into a character
-constant.
-
- If you want to stringify the result of expansion of a macro argument,
-you have to use two levels of macros.
-
- #define xstr(s) str(s)
- #define str(s) #s
- #define foo 4
- str (foo)
- ==> "foo"
- xstr (foo)
- ==> xstr (4)
- ==> str (4)
- ==> "4"
-
- `s' is stringified when it is used in `str', so it is not
-macro-expanded first. But `s' is an ordinary argument to `xstr', so it
-is completely macro-expanded before `xstr' itself is expanded (*note
-Argument Prescan::). Therefore, by the time `str' gets to its
-argument, it has already been macro-expanded.
-
-\1f
-File: cpp.info, Node: Concatenation, Next: Variadic Macros, Prev: Stringification, Up: Macros
-
-Concatenation
-=============
-
- It is often useful to merge two tokens into one while expanding
-macros. This is called "token pasting" or "token concatenation". The
-`##' preprocessing operator performs token pasting. When a macro is
-expanded, the two tokens on either side of each `##' operator are
-combined into a single token, which then replaces the `##' and the two
-original tokens in the macro expansion. Usually both will be
-identifiers, or one will be an identifier and the other a preprocessing
-number. When pasted, they make a longer identifier. This isn't the
-only valid case. It is also possible to concatenate two numbers (or a
-number and a name, such as `1.5' and `e3') into a number. Also,
-multi-character operators such as `+=' can be formed by token pasting.
-
- However, two tokens that don't together form a valid token cannot be
-pasted together. For example, you cannot concatenate `x' with `+' in
-either order. If you try, the preprocessor issues a warning and emits
-the two tokens. Whether it puts white space between the tokens is
-undefined. It is common to find unnecessary uses of `##' in complex
-macros. If you get this warning, it is likely that you can simply
-remove the `##'.
-
- Both the tokens combined by `##' could come from the macro body, but
-you could just as well write them as one token in the first place.
-Token pasting is most useful when one or both of the tokens comes from a
-macro argument. If either of the tokens next to an `##' is a parameter
-name, it is replaced by its actual argument before `##' executes. As
-with stringification, the actual argument is not macro-expanded first.
-If the argument is empty, that `##' has no effect.
-
- Keep in mind that the C preprocessor converts comments to whitespace
-before macros are even considered. Therefore, you cannot create a
-comment by concatenating `/' and `*'. You can put as much whitespace
-between `##' and its operands as you like, including comments, and you
-can put comments in arguments that will be concatenated. However, it
-is an error if `##' appears at either end of a macro body.
-
- Consider a C program that interprets named commands. There probably
-needs to be a table of commands, perhaps an array of structures declared
-as follows:
-
- struct command
- {
- char *name;
- void (*function) (void);
- };
-
- struct command commands[] =
- {
- { "quit", quit_command },
- { "help", help_command },
- ...
- };
-
- It would be cleaner not to have to give each command name twice,
-once in the string constant and once in the function name. A macro
-which takes the name of a command as an argument can make this
-unnecessary. The string constant can be created with stringification,
-and the function name by concatenating the argument with `_command'.
-Here is how it is done:
-
- #define COMMAND(NAME) { #NAME, NAME ## _command }
-
- struct command commands[] =
- {
- COMMAND (quit),
- COMMAND (help),
- ...
- };
-
-\1f
-File: cpp.info, Node: Variadic Macros, Next: Predefined Macros, Prev: Concatenation, Up: Macros
-
-Variadic Macros
-===============
-
- A macro can be declared to accept a variable number of arguments
-much as a function can. The syntax for defining the macro is similar
-to that of a function. Here is an example:
-
- #define eprintf(...) fprintf (stderr, __VA_ARGS__)
-
- This kind of macro is called "variadic". When the macro is invoked,
-all the tokens in its argument list after the last named argument (this
-macro has none), including any commas, become the "variable argument".
-This sequence of tokens replaces the identifier `__VA_ARGS__' in the
-macro body wherever it appears. Thus, we have this expansion:
-
- eprintf ("%s:%d: ", input_file, lineno)
- ==> fprintf (stderr, "%s:%d: ", input_file, lineno)
-
- The variable argument is completely macro-expanded before it is
-inserted into the macro expansion, just like an ordinary argument. You
-may use the `#' and `##' operators to stringify the variable argument
-or to paste its leading or trailing token with another token. (But see
-below for an important special case for `##'.)
-
- If your macro is complicated, you may want a more descriptive name
-for the variable argument than `__VA_ARGS__'. GNU CPP permits this, as
-an extension. You may write an argument name immediately before the
-`...'; that name is used for the variable argument. The `eprintf'
-macro above could be written
-
- #define eprintf(args...) fprintf (stderr, args)
-
-using this extension. You cannot use `__VA_ARGS__' and this extension
-in the same macro.
-
- You can have named arguments as well as variable arguments in a
-variadic macro. We could define `eprintf' like this, instead:
-
- #define eprintf(format, ...) fprintf (stderr, format, __VA_ARGS__)
-
-This formulation looks more descriptive, but unfortunately it is less
-flexible: you must now supply at least one argument after the format
-string. In standard C, you cannot omit the comma separating the named
-argument from the variable arguments. Furthermore, if you leave the
-variable argument empty, you will get a syntax error, because there
-will be an extra comma after the format string.
-
- eprintf("success!\n", );
- ==> fprintf(stderr, "success!\n", );
-
- GNU CPP has a pair of extensions which deal with this problem.
-First, you are allowed to leave the variable argument out entirely:
-
- eprintf ("success!\n")
- ==> fprintf(stderr, "success!\n", );
-
-Second, the `##' token paste operator has a special meaning when placed
-between a comma and a variable argument. If you write
-
- #define eprintf(format, ...) fprintf (stderr, format, ##__VA_ARGS__)
-
-and the variable argument is left out when the `eprintf' macro is used,
-then the comma before the `##' will be deleted. This does _not_ happen
-if you pass an empty argument, nor does it happen if the token
-preceding `##' is anything other than a comma.
-
- eprintf ("success!\n")
- ==> fprintf(stderr, "success!\n");
-
-The above explanation is ambiguous about the case where the only macro
-parameter is a variable arguments parameter, as it is meaningless to
-try to distinguish whether no argument at all is an empty argument or a
-missing argument. In this case the C99 standard is clear that the
-comma must remain, however the existing GCC extension used to swallow
-the comma. So CPP retains the comma when conforming to a specific C
-standard, and drops it otherwise.
-
- C99 mandates that the only place the identifier `__VA_ARGS__' can
-appear is in the replacement list of a variadic macro. It may not be
-used as a macro name, macro argument name, or within a different type
-of macro. It may also be forbidden in open text; the standard is
-ambiguous. We recommend you avoid using it except for its defined
-purpose.
-
- Variadic macros are a new feature in C99. GNU CPP has supported them
-for a long time, but only with a named variable argument (`args...',
-not `...' and `__VA_ARGS__'). If you are concerned with portability to
-previous versions of GCC, you should use only named variable arguments.
-On the other hand, if you are concerned with portability to other
-conforming implementations of C99, you should use only `__VA_ARGS__'.
-
- Previous versions of GNU CPP implemented the comma-deletion extension
-much more generally. We have restricted it in this release to minimize
-the differences from C99. To get the same effect with both this and
-previous versions of GCC, the token preceding the special `##' must be
-a comma, and there must be white space between that comma and whatever
-comes immediately before it:
-
- #define eprintf(format, args...) fprintf (stderr, format , ##args)
-
-*Note Differences from previous versions::, for the gory details.
-
-\1f
-File: cpp.info, Node: Predefined Macros, Next: Undefining and Redefining Macros, Prev: Variadic Macros, Up: Macros
-
-Predefined Macros
-=================
-
- Several object-like macros are predefined; you use them without
-supplying their definitions. They fall into three classes: standard,
-common, and system-specific.
-
- In C++, there is a fourth category, the named operators. They act
-like predefined macros, but you cannot undefine them.
-
-* Menu:
-
-* Standard Predefined Macros::
-* Common Predefined Macros::
-* System-specific Predefined Macros::
-* C++ Named Operators::
-
-\1f
-File: cpp.info, Node: Standard Predefined Macros, Next: Common Predefined Macros, Up: Predefined Macros
-
-Standard Predefined Macros
---------------------------
-
- The standard predefined macros are specified by the C and/or C++
-language standards, so they are available with all compilers that
-implement those standards. Older compilers may not provide all of
-them. Their names all start with double underscores.
-
-`__FILE__'
- This macro expands to the name of the current input file, in the
- form of a C string constant. This is the path by which the
- preprocessor opened the file, not the short name specified in
- `#include' or as the input file name argument. For example,
- `"/usr/local/include/myheader.h"' is a possible expansion of this
- macro.
-
-`__LINE__'
- This macro expands to the current input line number, in the form
- of a decimal integer constant. While we call it a predefined
- macro, it's a pretty strange macro, since its "definition" changes
- with each new line of source code.
-
- `__FILE__' and `__LINE__' are useful in generating an error message
-to report an inconsistency detected by the program; the message can
-state the source line at which the inconsistency was detected. For
-example,
-
- fprintf (stderr, "Internal error: "
- "negative string length "
- "%d at %s, line %d.",
- length, __FILE__, __LINE__);
-
- An `#include' directive changes the expansions of `__FILE__' and
-`__LINE__' to correspond to the included file. At the end of that
-file, when processing resumes on the input file that contained the
-`#include' directive, the expansions of `__FILE__' and `__LINE__'
-revert to the values they had before the `#include' (but `__LINE__' is
-then incremented by one as processing moves to the line after the
-`#include').
-
- A `#line' directive changes `__LINE__', and may change `__FILE__' as
-well. *Note Line Control::.
-
- C99 introduces `__func__', and GCC has provided `__FUNCTION__' for a
-long time. Both of these are strings containing the name of the
-current function (there are slight semantic differences; see the GCC
-manual). Neither of them is a macro; the preprocessor does not know the
-name of the current function. They tend to be useful in conjunction
-with `__FILE__' and `__LINE__', though.
-
-`__DATE__'
- This macro expands to a string constant that describes the date on
- which the preprocessor is being run. The string constant contains
- eleven characters and looks like `"Feb 12 1996"'. If the day of
- the month is less than 10, it is padded with a space on the left.
-
-`__TIME__'
- This macro expands to a string constant that describes the time at
- which the preprocessor is being run. The string constant contains
- eight characters and looks like `"23:59:01"'.
-
-`__STDC__'
- In normal operation, this macro expands to the constant 1, to
- signify that this compiler conforms to ISO Standard C. If GNU CPP
- is used with a compiler other than GCC, this is not necessarily
- true; however, the preprocessor always conforms to the standard,
- unless the `-traditional' option is used.
-
- This macro is not defined if the `-traditional' option is used.
-
- On some hosts, the system compiler uses a different convention,
- where `__STDC__' is normally 0, but is 1 if the user specifies
- strict conformance to the C Standard. GNU CPP follows the host
- convention when processing system header files, but when
- processing user files `__STDC__' is always 1. This has been
- reported to cause problems; for instance, some versions of Solaris
- provide X Windows headers that expect `__STDC__' to be either
- undefined or 1. *Note Invocation::.
-
-`__STDC_VERSION__'
- This macro expands to the C Standard's version number, a long
- integer constant of the form `YYYYMML' where YYYY and MM are the
- year and month of the Standard version. This signifies which
- version of the C Standard the compiler conforms to. Like
- `__STDC__', this is not necessarily accurate for the entire
- implementation, unless GNU CPP is being used with GCC.
-
- The value `199409L' signifies the 1989 C standard as amended in
- 1994, which is the current default; the value `199901L' signifies
- the 1999 revision of the C standard. Support for the 1999
- revision is not yet complete.
-
- This macro is not defined if the `-traditional' option is used, nor
- when compiling C++ or Objective-C.
-
-`__STDC_HOSTED__'
- This macro is defined, with value 1, if the compiler's target is a
- "hosted environment". A hosted environment has the complete
- facilities of the standard C library available.
-
-`__cplusplus'
- This macro is defined when the C++ compiler is in use. You can use
- `__cplusplus' to test whether a header is compiled by a C compiler
- or a C++ compiler. This macro is similar to `__STDC_VERSION__', in
- that it expands to a version number. A fully conforming
- implementation of the 1998 C++ standard will define this macro to
- `199711L'. The GNU C++ compiler is not yet fully conforming, so
- it uses `1' instead. We hope to complete our implementation in
- the near future.
-
-
-\1f
-File: cpp.info, Node: Common Predefined Macros, Next: System-specific Predefined Macros, Prev: Standard Predefined Macros, Up: Predefined Macros
-
-Common Predefined Macros
-------------------------
-
- The common predefined macros are GNU C extensions. They are
-available with the same meanings regardless of the machine or operating
-system on which you are using GNU C. Their names all start with double
-underscores.
-
-`__GNUC__'
-`__GNUC_MINOR__'
-`__GNUC_PATCHLEVEL__'
- These macros are defined by all GNU compilers that use the C
- preprocessor: C, C++, and Objective-C. Their values are the major
- version, minor version, and patch level of the compiler, as integer
- constants. For example, GCC 3.2.1 will define `__GNUC__' to 3,
- `__GNUC_MINOR__' to 2, and `__GNUC_PATCHLEVEL__' to 1. They are
- defined only when the entire compiler is in use; if you invoke the
- preprocessor directly, they are not defined.
-
- `__GNUC_PATCHLEVEL__' is new to GCC 3.0; it is also present in the
- widely-used development snapshots leading up to 3.0 (which identify
- themselves as GCC 2.96 or 2.97, depending on which snapshot you
- have).
-
- If all you need to know is whether or not your program is being
- compiled by GCC, you can simply test `__GNUC__'. If you need to
- write code which depends on a specific version, you must be more
- careful. Each time the minor version is increased, the patch
- level is reset to zero; each time the major version is increased
- (which happens rarely), the minor version and patch level are
- reset. If you wish to use the predefined macros directly in the
- conditional, you will need to write it like this:
-
- /* Test for GCC > 3.2.0 */
- #if __GNUC__ > 3 || \
- (__GNUC__ == 3 && (__GNUC_MINOR__ > 2 || \
- (__GNUC_MINOR__ == 2 && \
- __GNUC_PATCHLEVEL__ > 0))
-
- Another approach is to use the predefined macros to calculate a
- single number, then compare that against a threshold:
-
- #define GCC_VERSION (__GNUC__ * 10000 \
- + __GNUC_MINOR__ * 100 \
- + __GNUC_PATCHLEVEL__)
- ...
- /* Test for GCC > 3.2.0 */
- #if GCC_VERSION > 30200
-
- Many people find this form easier to understand.
-
-`__OBJC__'
- This macro is defined, with value 1, when the Objective-C compiler
- is in use. You can use `__OBJC__' to test whether a header is
- compiled by a C compiler or a Objective-C compiler.
-
-`__GNUG__'
- The GNU C++ compiler defines this. Testing it is equivalent to
- testing `(__GNUC__ && __cplusplus)'.
-
-`__STRICT_ANSI__'
- GCC defines this macro if and only if the `-ansi' switch, or a
- `-std' switch specifying strict conformance to some version of ISO
- C, was specified when GCC was invoked. It is defined to `1'.
- This macro exists primarily to direct GNU libc's header files to
- restrict their definitions to the minimal set found in the 1989 C
- standard.
-
-`__BASE_FILE__'
- This macro expands to the name of the main input file, in the form
- of a C string constant. This is the source file that was specified
- on the command line of the preprocessor or C compiler.
-
-`__INCLUDE_LEVEL__'
- This macro expands to a decimal integer constant that represents
- the depth of nesting in include files. The value of this macro is
- incremented on every `#include' directive and decremented at the
- end of every included file. It starts out at 0, it's value within
- the base file specified on the command line.
-
-`__VERSION__'
- This macro expands to a string constant which describes the
- version of the compiler in use. You should not rely on its
- contents having any particular form, but it can be counted on to
- contain at least the release number.
-
-`__OPTIMIZE__'
-`__OPTIMIZE_SIZE__'
-`__NO_INLINE__'
- These macros describe the compilation mode. `__OPTIMIZE__' is
- defined in all optimizing compilations. `__OPTIMIZE_SIZE__' is
- defined if the compiler is optimizing for size, not speed.
- `__NO_INLINE__' is defined if no functions will be inlined into
- their callers (when not optimizing, or when inlining has been
- specifically disabled by `-fno-inline').
-
- These macros cause certain GNU header files to provide optimized
- definitions, using macros or inline functions, of system library
- functions. You should not use these macros in any way unless you
- make sure that programs will execute with the same effect whether
- or not they are defined. If they are defined, their value is 1.
-
-`__CHAR_UNSIGNED__'
- GCC defines this macro if and only if the data type `char' is
- unsigned on the target machine. It exists to cause the standard
- header file `limits.h' to work correctly. You should not use this
- macro yourself; instead, refer to the standard macros defined in
- `limits.h'.
-
-`__REGISTER_PREFIX__'
- This macro expands to a single token (not a string constant) which
- is the prefix applied to CPU register names in assembly language
- for this target. You can use it to write assembly that is usable
- in multiple environments. For example, in the `m68k-aout'
- environment it expands to nothing, but in the `m68k-coff'
- environment it expands to a single `%'.
-
-`__USER_LABEL_PREFIX__'
- This macro expands to a single token which is the prefix applied to
- user labels (symbols visible to C code) in assembly. For example,
- in the `m68k-aout' environment it expands to an `_', but in the
- `m68k-coff' environment it expands to nothing.
-
- This macro will have the correct definition even if
- `-f(no-)underscores' is in use, but it will not be correct if
- target-specific options that adjust this prefix are used (e.g. the
- OSF/rose `-mno-underscores' option).
-
-`__SIZE_TYPE__'
-`__PTRDIFF_TYPE__'
-`__WCHAR_TYPE__'
-`__WINT_TYPE__'
- These macros are defined to the correct underlying types for the
- `size_t', `ptrdiff_t', `wchar_t', and `wint_t' typedefs,
- respectively. They exist to make the standard header files
- `stddef.h' and `wchar.h' work correctly. You should not use these
- macros directly; instead, include the appropriate headers and use
- the typedefs.
-
-`__USING_SJLJ_EXCEPTIONS__'
- This macro is defined, with value 1, if the compiler uses the old
- mechanism based on `setjmp' and `longjmp' for exception handling.
-
-\1f
-File: cpp.info, Node: System-specific Predefined Macros, Next: C++ Named Operators, Prev: Common Predefined Macros, Up: Predefined Macros
-
-System-specific Predefined Macros
----------------------------------
-
- The C preprocessor normally predefines several macros that indicate
-what type of system and machine is in use. They are obviously
-different on each target supported by GCC. This manual, being for all
-systems and machines, cannot tell you what their names are, but you can
-use `cpp -dM' to see them all. *Note Invocation::. All system-specific
-predefined macros expand to the constant 1, so you can test them with
-either `#ifdef' or `#if'.
-
- The C standard requires that all system-specific macros be part of
-the "reserved namespace". All names which begin with two underscores,
-or an underscore and a capital letter, are reserved for the compiler and
-library to use as they wish. However, historically system-specific
-macros have had names with no special prefix; for instance, it is common
-to find `unix' defined on Unix systems. For all such macros, GCC
-provides a parallel macro with two underscores added at the beginning
-and the end. If `unix' is defined, `__unix__' will be defined too.
-There will never be more than two underscores; the parallel of `_mips'
-is `__mips__'.
-
- When the `-ansi' option, or any `-std' option that requests strict
-conformance, is given to the compiler, all the system-specific
-predefined macros outside the reserved namespace are suppressed. The
-parallel macros, inside the reserved namespace, remain defined.
-
- We are slowly phasing out all predefined macros which are outside the
-reserved namespace. You should never use them in new programs, and we
-encourage you to correct older code to use the parallel macros whenever
-you find it. We don't recommend you use the system-specific macros that
-are in the reserved namespace, either. It is better in the long run to
-check specifically for features you need, using a tool such as
-`autoconf'.
-
-\1f
-File: cpp.info, Node: C++ Named Operators, Prev: System-specific Predefined Macros, Up: Predefined Macros
-
-C++ Named Operators
--------------------
-
- In C++, there are eleven keywords which are simply alternate
-spellings of operators normally written with punctuation. These
-keywords are treated as such even in the preprocessor. They function
-as operators in `#if', and they cannot be defined as macros or
-poisoned. In C, you can request that those keywords take their C++
-meaning by including `iso646.h'. That header defines each one as a
-normal object-like macro expanding to the appropriate punctuator.
-
- These are the named operators and their corresponding punctuators:
-
-Named Operator Punctuator
-`and' `&&'
-`and_eq' `&='
-`bitand' `&'
-`bitor' `|'
-`compl' `~'
-`not' `!'
-`not_eq' `!='
-`or' `||'
-`or_eq' `|='
-`xor' `^'
-`xor_eq' `^='
-
-\1f
-File: cpp.info, Node: Undefining and Redefining Macros, Next: Macro Pitfalls, Prev: Predefined Macros, Up: Macros
-
-Undefining and Redefining Macros
-================================
-
- If a macro ceases to be useful, it may be "undefined" with the
-`#undef' directive. `#undef' takes a single argument, the name of the
-macro to undefine. You use the bare macro name, even if the macro is
-function-like. It is an error if anything appears on the line after
-the macro name. `#undef' has no effect if the name is not a macro.
-
- #define FOO 4
- x = FOO; ==> x = 4;
- #undef FOO
- x = FOO; ==> x = FOO;
-
- Once a macro has been undefined, that identifier may be "redefined"
-as a macro by a subsequent `#define' directive. The new definition
-need not have any resemblance to the old definition.
-
- However, if an identifier which is currently a macro is redefined,
-then the new definition must be "effectively the same" as the old one.
-Two macro definitions are effectively the same if:
- * Both are the same type of macro (object- or function-like).
-
- * All the tokens of the replacement list are the same.
-
- * If there are any parameters, they are the same.
-
- * Whitespace appears in the same places in both. It need not be
- exactly the same amount of whitespace, though. Remember that
- comments count as whitespace.
-
-These definitions are effectively the same:
- #define FOUR (2 + 2)
- #define FOUR (2 + 2)
- #define FOUR (2 /* two */ + 2)
-
-but these are not:
- #define FOUR (2 + 2)
- #define FOUR ( 2+2 )
- #define FOUR (2 * 2)
- #define FOUR(score,and,seven,years,ago) (2 + 2)
-
- If a macro is redefined with a definition that is not effectively the
-same as the old one, the preprocessor issues a warning and changes the
-macro to use the new definition. If the new definition is effectively
-the same, the redefinition is silently ignored. This allows, for
-instance, two different headers to define a common macro. The
-preprocessor will only complain if the definitions do not match.
-
-\1f
-File: cpp.info, Node: Macro Pitfalls, Prev: Undefining and Redefining Macros, Up: Macros
-
-Macro Pitfalls
-==============
-
- In this section we describe some special rules that apply to macros
-and macro expansion, and point out certain cases in which the rules have
-counter-intuitive consequences that you must watch out for.
-
-* Menu:
-
-* Misnesting::
-* Operator Precedence Problems::
-* Swallowing the Semicolon::
-* Duplication of Side Effects::
-* Self-Referential Macros::
-* Argument Prescan::
-* Newlines in Arguments::
-
-\1f
-File: cpp.info, Node: Misnesting, Next: Operator Precedence Problems, Up: Macro Pitfalls
-
-Misnesting
-----------
-
- When a macro is called with arguments, the arguments are substituted
-into the macro body and the result is checked, together with the rest of
-the input file, for more macro calls. It is possible to piece together
-a macro call coming partially from the macro body and partially from the
-arguments. For example,
-
- #define twice(x) (2*(x))
- #define call_with_1(x) x(1)
- call_with_1 (twice)
- ==> twice(1)
- ==> (2*(1))
-
- Macro definitions do not have to have balanced parentheses. By
-writing an unbalanced open parenthesis in a macro body, it is possible
-to create a macro call that begins inside the macro body but ends
-outside of it. For example,
-
- #define strange(file) fprintf (file, "%s %d",
- ...
- strange(stderr) p, 35)
- ==> fprintf (stderr, "%s %d", p, 35)
-
- The ability to piece together a macro call can be useful, but the
-use of unbalanced open parentheses in a macro body is just confusing,
-and should be avoided.
-
-\1f
-File: cpp.info, Node: Operator Precedence Problems, Next: Swallowing the Semicolon, Prev: Misnesting, Up: Macro Pitfalls
-
-Operator Precedence Problems
-----------------------------
-
- You may have noticed that in most of the macro definition examples
-shown above, each occurrence of a macro argument name had parentheses
-around it. In addition, another pair of parentheses usually surround
-the entire macro definition. Here is why it is best to write macros
-that way.
-
- Suppose you define a macro as follows,
-
- #define ceil_div(x, y) (x + y - 1) / y
-
-whose purpose is to divide, rounding up. (One use for this operation is
-to compute how many `int' objects are needed to hold a certain number
-of `char' objects.) Then suppose it is used as follows:
-
- a = ceil_div (b & c, sizeof (int));
- ==> a = (b & c + sizeof (int) - 1) / sizeof (int);
-
-This does not do what is intended. The operator-precedence rules of C
-make it equivalent to this:
-
- a = (b & (c + sizeof (int) - 1)) / sizeof (int);
-
-What we want is this:
-
- a = ((b & c) + sizeof (int) - 1)) / sizeof (int);
-
-Defining the macro as
-
- #define ceil_div(x, y) ((x) + (y) - 1) / (y)
-
-provides the desired result.
-
- Unintended grouping can result in another way. Consider `sizeof
-ceil_div(1, 2)'. That has the appearance of a C expression that would
-compute the size of the type of `ceil_div (1, 2)', but in fact it means
-something very different. Here is what it expands to:
-
- sizeof ((1) + (2) - 1) / (2)
-
-This would take the size of an integer and divide it by two. The
-precedence rules have put the division outside the `sizeof' when it was
-intended to be inside.
-
- Parentheses around the entire macro definition prevent such problems.
-Here, then, is the recommended way to define `ceil_div':
-
- #define ceil_div(x, y) (((x) + (y) - 1) / (y))
-
-\1f
-File: cpp.info, Node: Swallowing the Semicolon, Next: Duplication of Side Effects, Prev: Operator Precedence Problems, Up: Macro Pitfalls
-
-Swallowing the Semicolon
-------------------------
-
- Often it is desirable to define a macro that expands into a compound
-statement. Consider, for example, the following macro, that advances a
-pointer (the argument `p' says where to find it) across whitespace
-characters:
-
- #define SKIP_SPACES(p, limit) \
- { char *lim = (limit); \
- while (p < lim) { \
- if (*p++ != ' ') { \
- p--; break; }}}
-
-Here backslash-newline is used to split the macro definition, which must
-be a single logical line, so that it resembles the way such code would
-be laid out if not part of a macro definition.
-
- A call to this macro might be `SKIP_SPACES (p, lim)'. Strictly
-speaking, the call expands to a compound statement, which is a complete
-statement with no need for a semicolon to end it. However, since it
-looks like a function call, it minimizes confusion if you can use it
-like a function call, writing a semicolon afterward, as in `SKIP_SPACES
-(p, lim);'
-
- This can cause trouble before `else' statements, because the
-semicolon is actually a null statement. Suppose you write
-
- if (*p != 0)
- SKIP_SPACES (p, lim);
- else ...
-
-The presence of two statements--the compound statement and a null
-statement--in between the `if' condition and the `else' makes invalid C
-code.
-
- The definition of the macro `SKIP_SPACES' can be altered to solve
-this problem, using a `do ... while' statement. Here is how:
-
- #define SKIP_SPACES(p, limit) \
- do { char *lim = (limit); \
- while (p < lim) { \
- if (*p++ != ' ') { \
- p--; break; }}} \
- while (0)
-
- Now `SKIP_SPACES (p, lim);' expands into
-
- do {...} while (0);
-
-which is one statement. The loop executes exactly once; most compilers
-generate no extra code for it.
-
-\1f
-File: cpp.info, Node: Duplication of Side Effects, Next: Self-Referential Macros, Prev: Swallowing the Semicolon, Up: Macro Pitfalls
-
-Duplication of Side Effects
----------------------------
-
- Many C programs define a macro `min', for "minimum", like this:
-
- #define min(X, Y) ((X) < (Y) ? (X) : (Y))
-
- When you use this macro with an argument containing a side effect,
-as shown here,
-
- next = min (x + y, foo (z));
-
-it expands as follows:
-
- next = ((x + y) < (foo (z)) ? (x + y) : (foo (z)));
-
-where `x + y' has been substituted for `X' and `foo (z)' for `Y'.
-
- The function `foo' is used only once in the statement as it appears
-in the program, but the expression `foo (z)' has been substituted twice
-into the macro expansion. As a result, `foo' might be called two times
-when the statement is executed. If it has side effects or if it takes
-a long time to compute, the results might not be what you intended. We
-say that `min' is an "unsafe" macro.
-
- The best solution to this problem is to define `min' in a way that
-computes the value of `foo (z)' only once. The C language offers no
-standard way to do this, but it can be done with GNU extensions as
-follows:
-
- #define min(X, Y) \
- ({ typeof (X) x_ = (X); \
- typeof (Y) y_ = (Y); \
- (x_ < y_) ? x_ : y_; })
-
- The `({ ... })' notation produces a compound statement that acts as
-an expression. Its value is the value of its last statement. This
-permits us to define local variables and assign each argument to one.
-The local variables have underscores after their names to reduce the
-risk of conflict with an identifier of wider scope (it is impossible to
-avoid this entirely). Now each argument is evaluated exactly once.
-
- If you do not wish to use GNU C extensions, the only solution is to
-be careful when _using_ the macro `min'. For example, you can
-calculate the value of `foo (z)', save it in a variable, and use that
-variable in `min':
-
- #define min(X, Y) ((X) < (Y) ? (X) : (Y))
- ...
- {
- int tem = foo (z);
- next = min (x + y, tem);
- }
-
-(where we assume that `foo' returns type `int').
-
-\1f
-File: cpp.info, Node: Self-Referential Macros, Next: Argument Prescan, Prev: Duplication of Side Effects, Up: Macro Pitfalls
-
-Self-Referential Macros
------------------------
-
- A "self-referential" macro is one whose name appears in its
-definition. Recall that all macro definitions are rescanned for more
-macros to replace. If the self-reference were considered a use of the
-macro, it would produce an infinitely large expansion. To prevent this,
-the self-reference is not considered a macro call. It is passed into
-the preprocessor output unchanged. Let's consider an example:
-
- #define foo (4 + foo)
-
-where `foo' is also a variable in your program.
-
- Following the ordinary rules, each reference to `foo' will expand
-into `(4 + foo)'; then this will be rescanned and will expand into `(4
-+ (4 + foo))'; and so on until the computer runs out of memory.
-
- The self-reference rule cuts this process short after one step, at
-`(4 + foo)'. Therefore, this macro definition has the possibly useful
-effect of causing the program to add 4 to the value of `foo' wherever
-`foo' is referred to.
-
- In most cases, it is a bad idea to take advantage of this feature. A
-person reading the program who sees that `foo' is a variable will not
-expect that it is a macro as well. The reader will come across the
-identifier `foo' in the program and think its value should be that of
-the variable `foo', whereas in fact the value is four greater.
-
- One common, useful use of self-reference is to create a macro which
-expands to itself. If you write
-
- #define EPERM EPERM
-
-then the macro `EPERM' expands to `EPERM'. Effectively, it is left
-alone by the preprocessor whenever it's used in running text. You can
-tell that it's a macro with `#ifdef'. You might do this if you want to
-define numeric constants with an `enum', but have `#ifdef' be true for
-each constant.
-
- If a macro `x' expands to use a macro `y', and the expansion of `y'
-refers to the macro `x', that is an "indirect self-reference" of `x'.
-`x' is not expanded in this case either. Thus, if we have
-
- #define x (4 + y)
- #define y (2 * x)
-
-then `x' and `y' expand as follows:
-
- x ==> (4 + y)
- ==> (4 + (2 * x))
-
- y ==> (2 * x)
- ==> (2 * (4 + y))
-
-Each macro is expanded when it appears in the definition of the other
-macro, but not when it indirectly appears in its own definition.
-
-\1f
-File: cpp.info, Node: Argument Prescan, Next: Newlines in Arguments, Prev: Self-Referential Macros, Up: Macro Pitfalls
-
-Argument Prescan
-----------------
-
- Macro arguments are completely macro-expanded before they are
-substituted into a macro body, unless they are stringified or pasted
-with other tokens. After substitution, the entire macro body, including
-the substituted arguments, is scanned again for macros to be expanded.
-The result is that the arguments are scanned _twice_ to expand macro
-calls in them.
-
- Most of the time, this has no effect. If the argument contained any
-macro calls, they are expanded during the first scan. The result
-therefore contains no macro calls, so the second scan does not change
-it. If the argument were substituted as given, with no prescan, the
-single remaining scan would find the same macro calls and produce the
-same results.
-
- You might expect the double scan to change the results when a
-self-referential macro is used in an argument of another macro (*note
-Self-Referential Macros::): the self-referential macro would be
-expanded once in the first scan, and a second time in the second scan.
-However, this is not what happens. The self-references that do not
-expand in the first scan are marked so that they will not expand in the
-second scan either.
-
- You might wonder, "Why mention the prescan, if it makes no
-difference? And why not skip it and make the preprocessor faster?"
-The answer is that the prescan does make a difference in three special
-cases:
-
- * Nested calls to a macro.
-
- We say that "nested" calls to a macro occur when a macro's argument
- contains a call to that very macro. For example, if `f' is a macro
- that expects one argument, `f (f (1))' is a nested pair of calls to
- `f'. The desired expansion is made by expanding `f (1)' and
- substituting that into the definition of `f'. The prescan causes
- the expected result to happen. Without the prescan, `f (1)' itself
- would be substituted as an argument, and the inner use of `f' would
- appear during the main scan as an indirect self-reference and
- would not be expanded.
-
- * Macros that call other macros that stringify or concatenate.
-
- If an argument is stringified or concatenated, the prescan does not
- occur. If you _want_ to expand a macro, then stringify or
- concatenate its expansion, you can do that by causing one macro to
- call another macro that does the stringification or concatenation.
- For instance, if you have
-
- #define AFTERX(x) X_ ## x
- #define XAFTERX(x) AFTERX(x)
- #define TABLESIZE 1024
- #define BUFSIZE TABLESIZE
-
- then `AFTERX(BUFSIZE)' expands to `X_BUFSIZE', and
- `XAFTERX(BUFSIZE)' expands to `X_1024'. (Not to `X_TABLESIZE'.
- Prescan always does a complete expansion.)
-
- * Macros used in arguments, whose expansions contain unshielded
- commas.
-
- This can cause a macro expanded on the second scan to be called
- with the wrong number of arguments. Here is an example:
-
- #define foo a,b
- #define bar(x) lose(x)
- #define lose(x) (1 + (x))
-
- We would like `bar(foo)' to turn into `(1 + (foo))', which would
- then turn into `(1 + (a,b))'. Instead, `bar(foo)' expands into
- `lose(a,b)', and you get an error because `lose' requires a single
- argument. In this case, the problem is easily solved by the same
- parentheses that ought to be used to prevent misnesting of
- arithmetic operations:
-
- #define foo (a,b)
- or
- #define bar(x) lose((x))
-
- The extra pair of parentheses prevents the comma in `foo''s
- definition from being interpreted as an argument separator.
-
-
-\1f
-File: cpp.info, Node: Newlines in Arguments, Prev: Argument Prescan, Up: Macro Pitfalls
-
-Newlines in Arguments
----------------------
-
- The invocation of a function-like macro can extend over many logical
-lines. However, in the present implementation, the entire expansion
-comes out on one line. Thus line numbers emitted by the compiler or
-debugger refer to the line the invocation started on, which might be
-different to the line containing the argument causing the problem.
-
- Here is an example illustrating this:
-
- #define ignore_second_arg(a,b,c) a; c
-
- ignore_second_arg (foo (),
- ignored (),
- syntax error);
-
-The syntax error triggered by the tokens `syntax error' results in an
-error message citing line three--the line of ignore_second_arg-- even
-though the problematic code comes from line five.
-
- We consider this a bug, and intend to fix it in the near future.
-
-\1f
-File: cpp.info, Node: Conditionals, Next: Diagnostics, Prev: Macros, Up: Top
-
-Conditionals
-************
-
- A "conditional" is a directive that instructs the preprocessor to
-select whether or not to include a chunk of code in the final token
-stream passed to the compiler. Preprocessor conditionals can test
-arithmetic expressions, or whether a name is defined as a macro, or both
-simultaneously using the special `defined' operator.
-
- A conditional in the C preprocessor resembles in some ways an `if'
-statement in C, but it is important to understand the difference between
-them. The condition in an `if' statement is tested during the
-execution of your program. Its purpose is to allow your program to
-behave differently from run to run, depending on the data it is
-operating on. The condition in a preprocessing conditional directive is
-tested when your program is compiled. Its purpose is to allow different
-code to be included in the program depending on the situation at the
-time of compilation.
-
- However, the distinction is becoming less clear. Modern compilers
-often do test `if' statements when a program is compiled, if their
-conditions are known not to vary at run time, and eliminate code which
-can never be executed. If you can count on your compiler to do this,
-you may find that your program is more readable if you use `if'
-statements with constant conditions (perhaps determined by macros). Of
-course, you can only use this to exclude code, not type definitions or
-other preprocessing directives, and you can only do it if the code
-remains syntactically valid when it is not to be used.
-
- GCC version 3 eliminates this kind of never-executed code even when
-not optimizing. Older versions did it only when optimizing.
-
-* Menu:
-
-* Conditional Uses::
-* Conditional Syntax::
-* Deleted Code::
-
-\1f
-File: cpp.info, Node: Conditional Uses, Next: Conditional Syntax, Up: Conditionals
-
-Conditional Uses
-================
-
- There are three general reasons to use a conditional.
-
- * A program may need to use different code depending on the machine
- or operating system it is to run on. In some cases the code for
- one operating system may be erroneous on another operating system;
- for example, it might refer to data types or constants that do not
- exist on the other system. When this happens, it is not enough to
- avoid executing the invalid code. Its mere presence will cause
- the compiler to reject the program. With a preprocessing
- conditional, the offending code can be effectively excised from
- the program when it is not valid.
-
- * You may want to be able to compile the same source file into two
- different programs. One version might make frequent time-consuming
- consistency checks on its intermediate data, or print the values of
- those data for debugging, and the other not.
-
- * A conditional whose condition is always false is one way to
- exclude code from the program but keep it as a sort of comment for
- future reference.
-
- Simple programs that do not need system-specific logic or complex
-debugging hooks generally will not need to use preprocessing
-conditionals.
-
-\1f
-File: cpp.info, Node: Conditional Syntax, Next: Deleted Code, Prev: Conditional Uses, Up: Conditionals
-
-Conditional Syntax
-==================
-
- A conditional in the C preprocessor begins with a "conditional
-directive": `#if', `#ifdef' or `#ifndef'.
-
-* Menu:
-
-* Ifdef::
-* If::
-* Defined::
-* Else::
-* Elif::
-
+++ /dev/null
-This is doc/cpp.info, produced by makeinfo version 4.5 from
-doc/cpp.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* Cpp: (cpp). The GNU C preprocessor.
-END-INFO-DIR-ENTRY
-
-\1f
-File: cpp.info, Node: Ifdef, Next: If, Up: Conditional Syntax
-
-Ifdef
------
-
- The simplest sort of conditional is
-
- #ifdef MACRO
-
- CONTROLLED TEXT
-
- #endif /* MACRO */
-
- This block is called a "conditional group". CONTROLLED TEXT will be
-included in the output of the preprocessor if and only if MACRO is
-defined. We say that the conditional "succeeds" if MACRO is defined,
-"fails" if it is not.
-
- The CONTROLLED TEXT inside of a conditional can include
-preprocessing directives. They are executed only if the conditional
-succeeds. You can nest conditional groups inside other conditional
-groups, but they must be completely nested. In other words, `#endif'
-always matches the nearest `#ifdef' (or `#ifndef', or `#if'). Also,
-you cannot start a conditional group in one file and end it in another.
-
- Even if a conditional fails, the CONTROLLED TEXT inside it is still
-run through initial transformations and tokenization. Therefore, it
-must all be lexically valid C. Normally the only way this matters is
-that all comments and string literals inside a failing conditional group
-must still be properly ended.
-
- The comment following the `#endif' is not required, but it is a good
-practice if there is a lot of CONTROLLED TEXT, because it helps people
-match the `#endif' to the corresponding `#ifdef'. Older programs
-sometimes put MACRO directly after the `#endif' without enclosing it in
-a comment. This is invalid code according to the C standard. GNU CPP
-accepts it with a warning. It never affects which `#ifndef' the
-`#endif' matches.
-
- Sometimes you wish to use some code if a macro is _not_ defined.
-You can do this by writing `#ifndef' instead of `#ifdef'. One common
-use of `#ifndef' is to include code only the first time a header file
-is included. *Note Once-Only Headers::.
-
- Macro definitions can vary between compilations for several reasons.
-Here are some samples.
-
- * Some macros are predefined on each kind of machine (*note
- System-specific Predefined Macros::). This allows you to provide
- code specially tuned for a particular machine.
-
- * System header files define more macros, associated with the
- features they implement. You can test these macros with
- conditionals to avoid using a system feature on a machine where it
- is not implemented.
-
- * Macros can be defined or undefined with the `-D' and `-U' command
- line options when you compile the program. You can arrange to
- compile the same source file into two different programs by
- choosing a macro name to specify which program you want, writing
- conditionals to test whether or how this macro is defined, and
- then controlling the state of the macro with command line options,
- perhaps set in the Makefile. *Note Invocation::.
-
- * Your program might have a special header file (often called
- `config.h') that is adjusted when the program is compiled. It can
- define or not define macros depending on the features of the
- system and the desired capabilities of the program. The
- adjustment can be automated by a tool such as `autoconf', or done
- by hand.
-
-\1f
-File: cpp.info, Node: If, Next: Defined, Prev: Ifdef, Up: Conditional Syntax
-
-If
---
-
- The `#if' directive allows you to test the value of an arithmetic
-expression, rather than the mere existence of one macro. Its syntax is
-
- #if EXPRESSION
-
- CONTROLLED TEXT
-
- #endif /* EXPRESSION */
-
- EXPRESSION is a C expression of integer type, subject to stringent
-restrictions. It may contain
-
- * Integer constants.
-
- * Character constants, which are interpreted as they would be in
- normal code.
-
- * Arithmetic operators for addition, subtraction, multiplication,
- division, bitwise operations, shifts, comparisons, and logical
- operations (`&&' and `||'). The latter two obey the usual
- short-circuiting rules of standard C.
-
- * Macros. All macros in the expression are expanded before actual
- computation of the expression's value begins.
-
- * Uses of the `defined' operator, which lets you check whether macros
- are defined in the middle of an `#if'.
-
- * Identifiers that are not macros, which are all considered to be the
- number zero. This allows you to write `#if MACRO' instead of
- `#ifdef MACRO', if you know that MACRO, when defined, will always
- have a nonzero value. Function-like macros used without their
- function call parentheses are also treated as zero.
-
- In some contexts this shortcut is undesirable. The `-Wundef'
- option causes GCC to warn whenever it encounters an identifier
- which is not a macro in an `#if'.
-
- The preprocessor does not know anything about types in the language.
-Therefore, `sizeof' operators are not recognized in `#if', and neither
-are `enum' constants. They will be taken as identifiers which are not
-macros, and replaced by zero. In the case of `sizeof', this is likely
-to cause the expression to be invalid.
-
- The preprocessor calculates the value of EXPRESSION. It carries out
-all calculations in the widest integer type known to the compiler; on
-most machines supported by GCC this is 64 bits. This is not the same
-rule as the compiler uses to calculate the value of a constant
-expression, and may give different results in some cases. If the value
-comes out to be nonzero, the `#if' succeeds and the CONTROLLED TEXT is
-included; otherwise it is skipped.
-
- If EXPRESSION is not correctly formed, GCC issues an error and
-treats the conditional as having failed.
-
-\1f
-File: cpp.info, Node: Defined, Next: Else, Prev: If, Up: Conditional Syntax
-
-Defined
--------
-
- The special operator `defined' is used in `#if' and `#elif'
-expressions to test whether a certain name is defined as a macro.
-`defined NAME' and `defined (NAME)' are both expressions whose value is
-1 if NAME is defined as a macro at the current point in the program,
-and 0 otherwise. Thus, `#if defined MACRO' is precisely equivalent to
-`#ifdef MACRO'.
-
- `defined' is useful when you wish to test more than one macro for
-existence at once. For example,
-
- #if defined (__vax__) || defined (__ns16000__)
-
-would succeed if either of the names `__vax__' or `__ns16000__' is
-defined as a macro.
-
- Conditionals written like this:
-
- #if defined BUFSIZE && BUFSIZE >= 1024
-
-can generally be simplified to just `#if BUFSIZE >= 1024', since if
-`BUFSIZE' is not defined, it will be interpreted as having the value
-zero.
-
- If the `defined' operator appears as a result of a macro expansion,
-the C standard says the behavior is undefined. GNU cpp treats it as a
-genuine `defined' operator and evaluates it normally. It will warn
-wherever your code uses this feature if you use the command-line option
-`-pedantic', since other compilers may handle it differently.
-
-\1f
-File: cpp.info, Node: Else, Next: Elif, Prev: Defined, Up: Conditional Syntax
-
-Else
-----
-
- The `#else' directive can be added to a conditional to provide
-alternative text to be used if the condition fails. This is what it
-looks like:
-
- #if EXPRESSION
- TEXT-IF-TRUE
- #else /* Not EXPRESSION */
- TEXT-IF-FALSE
- #endif /* Not EXPRESSION */
-
-If EXPRESSION is nonzero, the TEXT-IF-TRUE is included and the
-TEXT-IF-FALSE is skipped. If EXPRESSION is zero, the opposite happens.
-
- You can use `#else' with `#ifdef' and `#ifndef', too.
-
-\1f
-File: cpp.info, Node: Elif, Prev: Else, Up: Conditional Syntax
-
-Elif
-----
-
- One common case of nested conditionals is used to check for more
-than two possible alternatives. For example, you might have
-
- #if X == 1
- ...
- #else /* X != 1 */
- #if X == 2
- ...
- #else /* X != 2 */
- ...
- #endif /* X != 2 */
- #endif /* X != 1 */
-
- Another conditional directive, `#elif', allows this to be
-abbreviated as follows:
-
- #if X == 1
- ...
- #elif X == 2
- ...
- #else /* X != 2 and X != 1*/
- ...
- #endif /* X != 2 and X != 1*/
-
- `#elif' stands for "else if". Like `#else', it goes in the middle
-of a conditional group and subdivides it; it does not require a
-matching `#endif' of its own. Like `#if', the `#elif' directive
-includes an expression to be tested. The text following the `#elif' is
-processed only if the original `#if'-condition failed and the `#elif'
-condition succeeds.
-
- More than one `#elif' can go in the same conditional group. Then
-the text after each `#elif' is processed only if the `#elif' condition
-succeeds after the original `#if' and all previous `#elif' directives
-within it have failed.
-
- `#else' is allowed after any number of `#elif' directives, but
-`#elif' may not follow `#else'.
-
-\1f
-File: cpp.info, Node: Deleted Code, Prev: Conditional Syntax, Up: Conditionals
-
-Deleted Code
-============
-
- If you replace or delete a part of the program but want to keep the
-old code around for future reference, you often cannot simply comment it
-out. Block comments do not nest, so the first comment inside the old
-code will end the commenting-out. The probable result is a flood of
-syntax errors.
-
- One way to avoid this problem is to use an always-false conditional
-instead. For instance, put `#if 0' before the deleted code and
-`#endif' after it. This works even if the code being turned off
-contains conditionals, but they must be entire conditionals (balanced
-`#if' and `#endif').
-
- Some people use `#ifdef notdef' instead. This is risky, because
-`notdef' might be accidentally defined as a macro, and then the
-conditional would succeed. `#if 0' can be counted on to fail.
-
- Do not use `#if 0' for comments which are not C code. Use a real
-comment, instead. The interior of `#if 0' must consist of complete
-tokens; in particular, single-quote characters must balance. Comments
-often contain unbalanced single-quote characters (known in English as
-apostrophes). These confuse `#if 0'. They don't confuse `/*'.
-
-\1f
-File: cpp.info, Node: Diagnostics, Next: Line Control, Prev: Conditionals, Up: Top
-
-Diagnostics
-***********
-
- The directive `#error' causes the preprocessor to report a fatal
-error. The tokens forming the rest of the line following `#error' are
-used as the error message.
-
- You would use `#error' inside of a conditional that detects a
-combination of parameters which you know the program does not properly
-support. For example, if you know that the program will not run
-properly on a VAX, you might write
-
- #ifdef __vax__
- #error "Won't work on VAXen. See comments at get_last_object."
- #endif
-
- If you have several configuration parameters that must be set up by
-the installation in a consistent way, you can use conditionals to detect
-an inconsistency and report it with `#error'. For example,
-
- #if !defined(UNALIGNED_INT_ASM_OP) && defined(DWARF2_DEBUGGING_INFO)
- #error "DWARF2_DEBUGGING_INFO requires UNALIGNED_INT_ASM_OP."
- #endif
-
- The directive `#warning' is like `#error', but causes the
-preprocessor to issue a warning and continue preprocessing. The tokens
-following `#warning' are used as the warning message.
-
- You might use `#warning' in obsolete header files, with a message
-directing the user to the header file which should be used instead.
-
- Neither `#error' nor `#warning' macro-expands its argument.
-Internal whitespace sequences are each replaced with a single space.
-The line must consist of complete tokens. It is wisest to make the
-argument of these directives be a single string constant; this avoids
-problems with apostrophes and the like.
-
-\1f
-File: cpp.info, Node: Line Control, Next: Pragmas, Prev: Diagnostics, Up: Top
-
-Line Control
-************
-
- The C preprocessor informs the C compiler of the location in your
-source code where each token came from. Presently, this is just the
-file name and line number. All the tokens resulting from macro
-expansion are reported as having appeared on the line of the source
-file where the outermost macro was used. We intend to be more accurate
-in the future.
-
- If you write a program which generates source code, such as the
-`bison' parser generator, you may want to adjust the preprocessor's
-notion of the current file name and line number by hand. Parts of the
-output from `bison' are generated from scratch, other parts come from a
-standard parser file. The rest are copied verbatim from `bison''s
-input. You would like compiler error messages and symbolic debuggers
-to be able to refer to `bison''s input file.
-
- `bison' or any such program can arrange this by writing `#line'
-directives into the output file. `#line' is a directive that specifies
-the original line number and source file name for subsequent input in
-the current preprocessor input file. `#line' has three variants:
-
-`#line LINENUM'
- LINENUM is a non-negative decimal integer constant. It specifies
- the line number which should be reported for the following line of
- input. Subsequent lines are counted from LINENUM.
-
-`#line LINENUM FILENAME'
- LINENUM is the same as for the first form, and has the same
- effect. In addition, FILENAME is a string constant. The
- following line and all subsequent lines are reported to come from
- the file it specifies, until something else happens to change that.
- FILENAME is interpreted according to the normal rules for a string
- constant: backslash escapes are interpreted. This is different
- from `#include'.
-
- Previous versions of GNU CPP did not interpret escapes in `#line';
- we have changed it because the standard requires they be
- interpreted, and most other compilers do.
-
-`#line ANYTHING ELSE'
- ANYTHING ELSE is checked for macro calls, which are expanded. The
- result should match one of the above two forms.
-
- `#line' directives alter the results of the `__FILE__' and
-`__LINE__' predefined macros from that point on. *Note Standard
-Predefined Macros::. They do not have any effect on `#include''s idea
-of the directory containing the current file. This is a change from
-GCC 2.95. Previously, a file reading
-
- #line 1 "../src/gram.y"
- #include "gram.h"
-
- would search for `gram.h' in `../src', then the `-I' chain; the
-directory containing the physical source file would not be searched.
-In GCC 3.0 and later, the `#include' is not affected by the presence of
-a `#line' referring to a different directory.
-
- We made this change because the old behavior caused problems when
-generated source files were transported between machines. For instance,
-it is common practice to ship generated parsers with a source release,
-so that people building the distribution do not need to have yacc or
-Bison installed. These files frequently have `#line' directives
-referring to the directory tree of the system where the distribution was
-created. If GCC tries to search for headers in those directories, the
-build is likely to fail.
-
- The new behavior can cause failures too, if the generated file is not
-in the same directory as its source and it attempts to include a header
-which would be visible searching from the directory containing the
-source file. However, this problem is easily solved with an additional
-`-I' switch on the command line. The failures caused by the old
-semantics could sometimes be corrected only by editing the generated
-files, which is difficult and error-prone.
-
-\1f
-File: cpp.info, Node: Pragmas, Next: Other Directives, Prev: Line Control, Up: Top
-
-Pragmas
-*******
-
- The `#pragma' directive is the method specified by the C standard
-for providing additional information to the compiler, beyond what is
-conveyed in the language itself. Three forms of this directive
-(commonly known as "pragmas") are specified by the 1999 C standard. A
-C compiler is free to attach any meaning it likes to other pragmas.
-
- GCC has historically preferred to use extensions to the syntax of the
-language, such as `__attribute__', for this purpose. However, GCC does
-define a few pragmas of its own. These mostly have effects on the
-entire translation unit or source file.
-
- In GCC version 3, all GNU-defined, supported pragmas have been given
-a `GCC' prefix. This is in line with the `STDC' prefix on all pragmas
-defined by C99. For backward compatibility, pragmas which were
-recognized by previous versions are still recognized without the `GCC'
-prefix, but that usage is deprecated. Some older pragmas are
-deprecated in their entirety. They are not recognized with the `GCC'
-prefix. *Note Obsolete Features::.
-
- C99 introduces the `_Pragma' operator. This feature addresses a
-major problem with `#pragma': being a directive, it cannot be produced
-as the result of macro expansion. `_Pragma' is an operator, much like
-`sizeof' or `defined', and can be embedded in a macro.
-
- Its syntax is `_Pragma (STRING-LITERAL)', where STRING-LITERAL can
-be either a normal or wide-character string literal. It is
-destringized, by replacing all `\\' with a single `\' and all `\"' with
-a `"'. The result is then processed as if it had appeared as the right
-hand side of a `#pragma' directive. For example,
-
- _Pragma ("GCC dependency \"parse.y\"")
-
-has the same effect as `#pragma GCC dependency "parse.y"'. The same
-effect could be achieved using macros, for example
-
- #define DO_PRAGMA(x) _Pragma (#x)
- DO_PRAGMA (GCC dependency "parse.y")
-
- The standard is unclear on where a `_Pragma' operator can appear.
-The preprocessor does not accept it within a preprocessing conditional
-directive like `#if'. To be safe, you are probably best keeping it out
-of directives other than `#define', and putting it on a line of its own.
-
- This manual documents the pragmas which are meaningful to the
-preprocessor itself. Other pragmas are meaningful to the C or C++
-compilers. They are documented in the GCC manual.
-
-`#pragma GCC dependency'
- `#pragma GCC dependency' allows you to check the relative dates of
- the current file and another file. If the other file is more
- recent than the current file, a warning is issued. This is useful
- if the current file is derived from the other file, and should be
- regenerated. The other file is searched for using the normal
- include search path. Optional trailing text can be used to give
- more information in the warning message.
-
- #pragma GCC dependency "parse.y"
- #pragma GCC dependency "/usr/include/time.h" rerun fixincludes
-
-`#pragma GCC poison'
- Sometimes, there is an identifier that you want to remove
- completely from your program, and make sure that it never creeps
- back in. To enforce this, you can "poison" the identifier with
- this pragma. `#pragma GCC poison' is followed by a list of
- identifiers to poison. If any of those identifiers appears
- anywhere in the source after the directive, it is a hard error.
- For example,
-
- #pragma GCC poison printf sprintf fprintf
- sprintf(some_string, "hello");
-
- will produce an error.
-
- If a poisoned identifier appears as part of the expansion of a
- macro which was defined before the identifier was poisoned, it
- will _not_ cause an error. This lets you poison an identifier
- without worrying about system headers defining macros that use it.
-
- For example,
-
- #define strrchr rindex
- #pragma GCC poison rindex
- strrchr(some_string, 'h');
-
- will not produce an error.
-
-`#pragma GCC system_header'
- This pragma takes no arguments. It causes the rest of the code in
- the current file to be treated as if it came from a system header.
- *Note System Headers::.
-
-
-\1f
-File: cpp.info, Node: Other Directives, Next: Preprocessor Output, Prev: Pragmas, Up: Top
-
-Other Directives
-****************
-
- The `#ident' directive takes one argument, a string constant. On
-some systems, that string constant is copied into a special segment of
-the object file. On other systems, the directive is ignored.
-
- This directive is not part of the C standard, but it is not an
-official GNU extension either. We believe it came from System V.
-
- The `#sccs' directive is recognized on some systems, because it
-appears in their header files. It is a very old, obscure, extension
-which we did not invent, and we have been unable to find any
-documentation of what it should do, so GCC simply ignores it.
-
- The "null directive" consists of a `#' followed by a newline, with
-only whitespace (including comments) in between. A null directive is
-understood as a preprocessing directive but has no effect on the
-preprocessor output. The primary significance of the existence of the
-null directive is that an input line consisting of just a `#' will
-produce no output, rather than a line of output containing just a `#'.
-Supposedly some old C programs contain such lines.
-
-\1f
-File: cpp.info, Node: Preprocessor Output, Next: Traditional Mode, Prev: Other Directives, Up: Top
-
-Preprocessor Output
-*******************
-
- When the C preprocessor is used with the C, C++, or Objective-C
-compilers, it is integrated into the compiler and communicates a stream
-of binary tokens directly to the compiler's parser. However, it can
-also be used in the more conventional standalone mode, where it produces
-textual output.
-
- The output from the C preprocessor looks much like the input, except
-that all preprocessing directive lines have been replaced with blank
-lines and all comments with spaces. Long runs of blank lines are
-discarded.
-
- The ISO standard specifies that it is implementation defined whether
-a preprocessor preserves whitespace between tokens, or replaces it with
-e.g. a single space. In GNU CPP, whitespace between tokens is collapsed
-to become a single space, with the exception that the first token on a
-non-directive line is preceded with sufficient spaces that it appears in
-the same column in the preprocessed output that it appeared in the
-original source file. This is so the output is easy to read. *Note
-Differences from previous versions::. CPP does not insert any
-whitespace where there was none in the original source, except where
-necessary to prevent an accidental token paste.
-
- Source file name and line number information is conveyed by lines of
-the form
-
- # LINENUM FILENAME FLAGS
-
-These are called "linemarkers". They are inserted as needed into the
-output (but never within a string or character constant). They mean
-that the following line originated in file FILENAME at line LINENUM.
-FILENAME will never contain any non-printing characters; they are
-replaced with octal escape sequences.
-
- After the file name comes zero or more flags, which are `1', `2',
-`3', or `4'. If there are multiple flags, spaces separate them. Here
-is what the flags mean:
-
-`1'
- This indicates the start of a new file.
-
-`2'
- This indicates returning to a file (after having included another
- file).
-
-`3'
- This indicates that the following text comes from a system header
- file, so certain warnings should be suppressed.
-
-`4'
- This indicates that the following text should be treated as being
- wrapped in an implicit `extern "C"' block.
-
- As an extension, the preprocessor accepts linemarkers in
-non-assembler input files. They are treated like the corresponding
-`#line' directive, (*note Line Control::), except that trailing flags
-are permitted, and are interpreted with the meanings described above.
-If multiple flags are given, they must be in ascending order.
-
- Some directives may be duplicated in the output of the preprocessor.
-These are `#ident' (always), `#pragma' (only if the preprocessor does
-not handle the pragma itself), and `#define' and `#undef' (with certain
-debugging options). If this happens, the `#' of the directive will
-always be in the first column, and there will be no space between the
-`#' and the directive name. If macro expansion happens to generate
-tokens which might be mistaken for a duplicated directive, a space will
-be inserted between the `#' and the directive name.
-
-\1f
-File: cpp.info, Node: Traditional Mode, Next: Implementation Details, Prev: Preprocessor Output, Up: Top
-
-Traditional Mode
-****************
-
- Traditional (pre-standard) C preprocessing is rather different from
-the preprocessing specified by the standard. When GCC is given the
-`-traditional' option, it attempts to emulate a traditional
-preprocessor. We do not guarantee that GCC's behavior under
-`-traditional' matches any pre-standard preprocessor exactly.
-
- Traditional mode exists only for backward compatibility. We have no
-plans to augment it in any way nor will we change it except to fix
-catastrophic bugs. You should be aware that modern C libraries often
-have header files which are incompatible with traditional mode.
-
- This is a list of the differences. It may not be complete, and may
-not correspond exactly to the behavior of either GCC or a true
-traditional preprocessor.
-
- * Traditional macro expansion pays no attention to single-quote or
- double-quote characters; macro argument symbols are replaced by the
- argument values even when they appear within apparent string or
- character constants.
-
- * Traditionally, it is permissible for a macro expansion to end in
- the middle of a string or character constant. The constant
- continues into the text surrounding the macro call.
-
- * However, the end of the line terminates a string or character
- constant, with no error. (This is a kluge. Traditional mode is
- commonly used to preprocess things which are not C, and have a
- different comment syntax. Single apostrophes often appear in
- comments. This kluge prevents the traditional preprocessor from
- issuing errors on such comments.)
-
- * Preprocessing directives are recognized in traditional C only when
- their leading `#' appears in the first column. There can be no
- whitespace between the beginning of the line and the `#'.
-
- * In traditional C, a comment is equivalent to no text at all. (In
- ISO C, a comment counts as whitespace.) It can be used sort of
- the same way that `##' is used in ISO C, to paste macro arguments
- together.
-
- * Traditional C does not have the concept of a preprocessing number.
-
- * A macro is not suppressed within its own definition, in
- traditional C. Thus, any macro that is used recursively
- inevitably causes an error.
-
- * The `#' and `##' operators are not available in traditional C.
-
- * In traditional C, the text at the end of a macro expansion can run
- together with the text after the macro call, to produce a single
- token. This is impossible in ISO C.
-
- * None of the GNU extensions to the preprocessor are available in
- traditional mode, with the exception of a partial implementation of
- assertions, and those may be removed in the future.
-
- * A true traditional C preprocessor does not recognize `#elif',
- `#error', or `#pragma'. GCC supports `#elif' and `#error' even in
- traditional mode, but not `#pragma'.
-
- * Traditional mode is text-based, not token-based, and comments are
- stripped after macro expansion. Therefore, `/**/' can be used to
- paste tokens together provided that there is no whitespace between
- it and the tokens to be pasted.
-
- * Traditional mode preserves the amount and form of whitespace
- provided by the user. Hard tabs remain hard tabs. This can be
- useful, e.g. if you are preprocessing a Makefile (which we do not
- encourage).
-
- You can request warnings about features that did not exist, or worked
-differently, in traditional C with the `-Wtraditional' option. This
-works only if you do _not_ specify `-traditional'. GCC does not warn
-about features of ISO C which you must use when you are using a
-conforming compiler, such as the `#' and `##' operators.
-
- Presently `-Wtraditional' warns about:
-
- * Macro parameters that appear within string literals in the macro
- body. In traditional C macro replacement takes place within
- string literals, but does not in ISO C.
-
- * In traditional C, some preprocessor directives did not exist.
- Traditional preprocessors would only consider a line to be a
- directive if the `#' appeared in column 1 on the line. Therefore
- `-Wtraditional' warns about directives that traditional C
- understands but would ignore because the `#' does not appear as the
- first character on the line. It also suggests you hide directives
- like `#pragma' not understood by traditional C by indenting them.
- Some traditional implementations would not recognize `#elif', so it
- suggests avoiding it altogether.
-
- * A function-like macro that appears without an argument list. In
- traditional C this was an error. In ISO C it merely means that the
- macro is not expanded.
-
- * The unary plus operator. This did not exist in traditional C.
-
- * The `U' and `LL' integer constant suffixes, which were not
- available in traditional C. (Traditional C does support the `L'
- suffix for simple long integer constants.) You are not warned
- about uses of these suffixes in macros defined in system headers.
- For instance, `UINT_MAX' may well be defined as `4294967295U', but
- you will not be warned if you use `UINT_MAX'.
-
- You can usually avoid the warning, and the related warning about
- constants which are so large that they are unsigned, by writing the
- integer constant in question in hexadecimal, with no U suffix.
- Take care, though, because this gives the wrong result in exotic
- cases.
-
-\1f
-File: cpp.info, Node: Implementation Details, Next: Invocation, Prev: Traditional Mode, Up: Top
-
-Implementation Details
-**********************
-
- Here we document details of how the preprocessor's implementation
-affects its user-visible behavior. You should try to avoid undue
-reliance on behavior described here, as it is possible that it will
-change subtly in future implementations.
-
- Also documented here are obsolete features and changes from previous
-versions of GNU CPP.
-
-* Menu:
-
-* Implementation-defined behavior::
-* Implementation limits::
-* Obsolete Features::
-* Differences from previous versions::
-
-\1f
-File: cpp.info, Node: Implementation-defined behavior, Next: Implementation limits, Up: Implementation Details
-
-Implementation-defined behavior
-===============================
-
- This is how GNU CPP behaves in all the cases which the C standard
-describes as "implementation-defined". This term means that the
-implementation is free to do what it likes, but must document its choice
-and stick to it.
-
- * The mapping of physical source file multi-byte characters to the
- execution character set.
-
- Currently, GNU cpp only supports character sets that are strict
- supersets of ASCII, and performs no translation of characters.
-
- * Non-empty sequences of whitespace characters.
-
- In textual output, each whitespace sequence is collapsed to a
- single space. For aesthetic reasons, the first token on each
- non-directive line of output is preceded with sufficient spaces
- that it appears in the same column as it did in the original
- source file.
-
- * The numeric value of character constants in preprocessor
- expressions.
-
- The preprocessor and compiler interpret character constants in the
- same way; escape sequences such as `\a' are given the values they
- would have on the target machine.
-
- Multi-character character constants are interpreted a character at
- a time, shifting the previous result left by the number of bits per
- character on the host, and adding the new character. For example,
- 'ab' on an 8-bit host would be interpreted as 'a' * 256 + 'b'. If
- there are more characters in the constant than can fit in the
- widest native integer type on the host, usually a `long', the
- excess characters are ignored and a diagnostic is given.
-
- * Source file inclusion.
-
- For a discussion on how the preprocessor locates header files,
- *Note Include Operation::.
-
- * Interpretation of the filename resulting from a macro-expanded
- `#include' directive.
-
- *Note Computed Includes::.
-
- * Treatment of a `#pragma' directive that after macro-expansion
- results in a standard pragma.
-
- No macro expansion occurs on any `#pragma' directive line, so the
- question does not arise.
-
- Note that GCC does not yet implement any of the standard pragmas.
-
-
-\1f
-File: cpp.info, Node: Implementation limits, Next: Obsolete Features, Prev: Implementation-defined behavior, Up: Implementation Details
-
-Implementation limits
-=====================
-
- GNU CPP has a small number of internal limits. This section lists
-the limits which the C standard requires to be no lower than some
-minimum, and all the others we are aware of. We intend there to be as
-few limits as possible. If you encounter an undocumented or
-inconvenient limit, please report that to us as a bug. (See the
-section on reporting bugs in the GCC manual.)
-
- Where we say something is limited "only by available memory", that
-means that internal data structures impose no intrinsic limit, and space
-is allocated with `malloc' or equivalent. The actual limit will
-therefore depend on many things, such as the size of other things
-allocated by the compiler at the same time, the amount of memory
-consumed by other processes on the same computer, etc.
-
- * Nesting levels of `#include' files.
-
- We impose an arbitrary limit of 200 levels, to avoid runaway
- recursion. The standard requires at least 15 levels.
-
- * Nesting levels of conditional inclusion.
-
- The C standard mandates this be at least 63. GNU CPP is limited
- only by available memory.
-
- * Levels of parenthesised expressions within a full expression.
-
- The C standard requires this to be at least 63. In preprocessor
- conditional expressions, it is limited only by available memory.
-
- * Significant initial characters in an identifier or macro name.
-
- The preprocessor treats all characters as significant. The C
- standard requires only that the first 63 be significant.
-
- * Number of macros simultaneously defined in a single translation
- unit.
-
- The standard requires at least 4095 be possible. GNU CPP is
- limited only by available memory.
-
- * Number of parameters in a macro definition and arguments in a
- macro call.
-
- We allow `USHRT_MAX', which is no smaller than 65,535. The minimum
- required by the standard is 127.
-
- * Number of characters on a logical source line.
-
- The C standard requires a minimum of 4096 be permitted. GNU CPP
- places no limits on this, but you may get incorrect column numbers
- reported in diagnostics for lines longer than 65,535 characters.
-
- * Maximum size of a source file.
-
- The standard does not specify any lower limit on the maximum size
- of a source file. GNU cpp maps files into memory, so it is
- limited by the available address space. This is generally at
- least two gigabytes. Depending on the operating system, the size
- of physical memory may or may not be a limitation.
-
-
-\1f
-File: cpp.info, Node: Obsolete Features, Next: Differences from previous versions, Prev: Implementation limits, Up: Implementation Details
-
-Obsolete Features
-=================
-
- GNU CPP has a number of features which are present mainly for
-compatibility with older programs. We discourage their use in new code.
-In some cases, we plan to remove the feature in a future version of GCC.
-
-* Menu:
-
-* Assertions::
-* Obsolete once-only headers::
-* Miscellaneous obsolete features::
-
-\1f
-File: cpp.info, Node: Assertions, Next: Obsolete once-only headers, Up: Obsolete Features
-
-Assertions
-----------
-
- "Assertions" are a deprecated alternative to macros in writing
-conditionals to test what sort of computer or system the compiled
-program will run on. Assertions are usually predefined, but you can
-define them with preprocessing directives or command-line options.
-
- Assertions were intended to provide a more systematic way to describe
-the compiler's target system. However, in practice they are just as
-unpredictable as the system-specific predefined macros. In addition,
-they are not part of any standard, and only a few compilers support
-them. Therefore, the use of assertions is *less* portable than the use
-of system-specific predefined macros. We recommend you do not use them
-at all.
-
- An assertion looks like this:
-
- #PREDICATE (ANSWER)
-
-PREDICATE must be a single identifier. ANSWER can be any sequence of
-tokens; all characters are significant except for leading and trailing
-whitespace, and differences in internal whitespace sequences are
-ignored. (This is similar to the rules governing macro redefinition.)
-Thus, `(x + y)' is different from `(x+y)' but equivalent to
-`( x + y )'. Parentheses do not nest inside an answer.
-
- To test an assertion, you write it in an `#if'. For example, this
-conditional succeeds if either `vax' or `ns16000' has been asserted as
-an answer for `machine'.
-
- #if #machine (vax) || #machine (ns16000)
-
-You can test whether _any_ answer is asserted for a predicate by
-omitting the answer in the conditional:
-
- #if #machine
-
- Assertions are made with the `#assert' directive. Its sole argument
-is the assertion to make, without the leading `#' that identifies
-assertions in conditionals.
-
- #assert PREDICATE (ANSWER)
-
-You may make several assertions with the same predicate and different
-answers. Subsequent assertions do not override previous ones for the
-same predicate. All the answers for any given predicate are
-simultaneously true.
-
- Assertions can be cancelled with the `#unassert' directive. It has
-the same syntax as `#assert'. In that form it cancels only the answer
-which was specified on the `#unassert' line; other answers for that
-predicate remain true. You can cancel an entire predicate by leaving
-out the answer:
-
- #unassert PREDICATE
-
-In either form, if no such assertion has been made, `#unassert' has no
-effect.
-
- You can also make or cancel assertions using command line options.
-*Note Invocation::.
-
-\1f
-File: cpp.info, Node: Obsolete once-only headers, Next: Miscellaneous obsolete features, Prev: Assertions, Up: Obsolete Features
-
-Obsolete once-only headers
---------------------------
-
- GNU CPP supports two more ways of indicating that a header file
-should be read only once. Neither one is as portable as a wrapper
-`#ifndef', and we recommend you do not use them in new programs.
-
- In the Objective-C language, there is a variant of `#include' called
-`#import' which includes a file, but does so at most once. If you use
-`#import' instead of `#include', then you don't need the conditionals
-inside the header file to prevent multiple inclusion of the contents.
-GCC permits the use of `#import' in C and C++ as well as Objective-C.
-However, it is not in standard C or C++ and should therefore not be
-used by portable programs.
-
- `#import' is not a well designed feature. It requires the users of
-a header file to know that it should only be included once. It is much
-better for the header file's implementor to write the file so that users
-don't need to know this. Using a wrapper `#ifndef' accomplishes this
-goal.
-
- In the present implementation, a single use of `#import' will
-prevent the file from ever being read again, by either `#import' or
-`#include'. You should not rely on this; do not use both `#import' and
-`#include' to refer to the same header file.
-
- Another way to prevent a header file from being included more than
-once is with the `#pragma once' directive. If `#pragma once' is seen
-when scanning a header file, that file will never be read again, no
-matter what.
-
- `#pragma once' does not have the problems that `#import' does, but
-it is not recognized by all preprocessors, so you cannot rely on it in
-a portable program.
-
-\1f
-File: cpp.info, Node: Miscellaneous obsolete features, Prev: Obsolete once-only headers, Up: Obsolete Features
-
-Miscellaneous obsolete features
--------------------------------
-
- Here are a few more obsolete features.
-
- * Attempting to paste two tokens which together do not form a valid
- preprocessing token.
-
- The preprocessor currently warns about this, and the resulting
- preprocessed output is undefined. The tokens remain distinct if
- the preprocessor is being used directly by the compiler front end.
-
- Most of the time, when you get this warning, you will find that
- `##' is being used superstitiously, to guard against whitespace
- appearing between two tokens. It is almost always safe to delete
- the `##'.
-
- * `#pragma poison'
-
- This is the same as `#pragma GCC poison'. The version without the
- `GCC' prefix is deprecated. *Note Pragmas::.
-
- * Multi-line string constants
-
- GCC currently allows a string constant to extend across multiple
- logical lines of the source file. This extension is deprecated
- and will be removed in a future version of GCC. Such string
- constants are already rejected in all directives apart from
- `#define'.
-
- Instead, make use of ISO C concatenation of adjacent string
- literals, or use `\n' followed by a backslash-newline.
-
-
-\1f
-File: cpp.info, Node: Differences from previous versions, Prev: Obsolete Features, Up: Implementation Details
-
-Differences from previous versions
-==================================
-
- This section details behavior which has changed from previous
-versions of GNU CPP. We do not plan to change it again in the near
-future, but we do not promise not to, either.
-
- The "previous versions" discussed here are 2.95 and before. The
-behavior of GCC 3.0 is mostly the same as the behavior of the widely
-used 2.96 and 2.97 development snapshots. Where there are differences,
-they generally represent bugs in the snapshots.
-
- * Order of evaluation of `#' and `##' operators
-
- The standard does not specify the order of evaluation of a chain of
- `##' operators, nor whether `#' is evaluated before, after, or at
- the same time as `##'. You should therefore not write any code
- which depends on any specific ordering. It is possible to
- guarantee an ordering, if you need one, by suitable use of nested
- macros.
-
- An example of where this might matter is pasting the arguments `1',
- `e' and `-2'. This would be fine for left-to-right pasting, but
- right-to-left pasting would produce an invalid token `e-2'.
-
- GCC 3.0 evaluates `#' and `##' at the same time and strictly left
- to right. Older versions evaluated all `#' operators first, then
- all `##' operators, in an unreliable order.
-
- * The form of whitespace betwen tokens in preprocessor output
-
- *Note Preprocessor Output::, for the current textual format. This
- is also the format used by stringification. Normally, the
- preprocessor communicates tokens directly to the compiler's
- parser, and whitespace does not come up at all.
-
- Older versions of GCC preserved all whitespace provided by the
- user and inserted lots more whitespace of their own, because they
- could not accurately predict when extra spaces were needed to
- prevent accidental token pasting.
-
- * Optional argument when invoking rest argument macros
-
- As an extension, GCC permits you to omit the variable arguments
- entirely when you use a variable argument macro. This is
- forbidden by the 1999 C standard, and will provoke a pedantic
- warning with GCC 3.0. Previous versions accepted it silently.
-
- * `##' swallowing preceding text in rest argument macros
-
- Formerly, in a macro expansion, if `##' appeared before a variable
- arguments parameter, and the set of tokens specified for that
- argument in the macro invocation was empty, previous versions of
- GNU CPP would back up and remove the preceding sequence of
- non-whitespace characters (*not* the preceding token). This
- extension is in direct conflict with the 1999 C standard and has
- been drastically pared back.
-
- In the current version of the preprocessor, if `##' appears between
- a comma and a variable arguments parameter, and the variable
- argument is omitted entirely, the comma will be removed from the
- expansion. If the variable argument is empty, or the token before
- `##' is not a comma, then `##' behaves as a normal token paste.
-
- * Traditional mode and GNU extensions
-
- Traditional mode used to be implemented in the same program as
- normal preprocessing. Therefore, all the GNU extensions to the
- preprocessor were still available in traditional mode. It is now
- a separate program and does not implement any of the GNU
- extensions, except for a partial implementation of assertions.
- Even those may be removed in a future release.
-
- * `#line' and `#include'
-
- The `#line' directive used to change GCC's notion of the
- "directory containing the current file," used by `#include' with a
- double-quoted header file name. In 3.0 and later, it does not.
- *Note Line Control::, for further explanation.
-
- * Syntax of `#line'
-
- In GCC 2.95 and previous, the string constant argument to `#line'
- was treated the same way as the argument to `#include': backslash
- escapes were not honored, and the string ended at the second `"'.
- This is not compliant with the C standard. In GCC 3.0, an attempt
- was made to correct the behavior, so that the string was treated
- as a real string constant, but it turned out to be buggy. In 3.1,
- the bugs have been fixed. (We are not fixing the bugs in 3.0
- because they affect relatively few people and the fix is quite
- invasive.)
-
-
+++ /dev/null
-This is doc/cpp.info, produced by makeinfo version 4.5 from
-doc/cpp.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* Cpp: (cpp). The GNU C preprocessor.
-END-INFO-DIR-ENTRY
-
-\1f
-File: cpp.info, Node: Invocation, Next: Environment Variables, Prev: Implementation Details, Up: Top
-
-Invocation
-**********
-
- Most often when you use the C preprocessor you will not have to
-invoke it explicitly: the C compiler will do so automatically.
-However, the preprocessor is sometimes useful on its own. All the
-options listed here are also acceptable to the C compiler and have the
-same meaning, except that the C compiler has different rules for
-specifying the output file.
-
- *Note:* Whether you use the preprocessor by way of `gcc' or `cpp',
-the "compiler driver" is run first. This program's purpose is to
-translate your command into invocations of the programs that do the
-actual work. Their command line interfaces are similar but not
-identical to the documented interface, and may change without notice.
-
- The C preprocessor expects two file names as arguments, INFILE and
-OUTFILE. The preprocessor reads INFILE together with any other files
-it specifies with `#include'. All the output generated by the combined
-input files is written in OUTFILE.
-
- Either INFILE or OUTFILE may be `-', which as INFILE means to read
-from standard input and as OUTFILE means to write to standard output.
-Also, if either file is omitted, it means the same as if `-' had been
-specified for that file.
-
- Unless otherwise noted, or the option ends in `=', all options which
-take an argument may have that argument appear either immediately after
-the option, or with a space between option and argument: `-Ifoo' and
-`-I foo' have the same effect.
-
- Many options have multi-letter names; therefore multiple
-single-letter options may _not_ be grouped: `-dM' is very different from
-`-d -M'.
-
-`-D NAME'
- Predefine NAME as a macro, with definition `1'.
-
-`-D NAME=DEFINITION'
- Predefine NAME as a macro, with definition DEFINITION. There are
- no restrictions on the contents of DEFINITION, but if you are
- invoking the preprocessor from a shell or shell-like program you
- may need to use the shell's quoting syntax to protect characters
- such as spaces that have a meaning in the shell syntax.
-
- If you wish to define a function-like macro on the command line,
- write its argument list with surrounding parentheses before the
- equals sign (if any). Parentheses are meaningful to most shells,
- so you will need to quote the option. With `sh' and `csh',
- `-D'NAME(ARGS...)=DEFINITION'' works.
-
- `-D' and `-U' options are processed in the order they are given on
- the command line. All `-imacros FILE' and `-include FILE' options
- are processed after all `-D' and `-U' options.
-
-`-U NAME'
- Cancel any previous definition of NAME, either built in or
- provided with a `-D' option.
-
-`-undef'
- Do not predefine any system-specific macros. The common predefined
- macros remain defined.
-
-`-I DIR'
- Add the directory DIR to the list of directories to be searched
- for header files. *Note Search Path::. Directories named by `-I'
- are searched before the standard system include directories.
-
- It is dangerous to specify a standard system include directory in
- an `-I' option. This defeats the special treatment of system
- headers (*note System Headers::) . It can also defeat the repairs
- to buggy system headers which GCC makes when it is installed.
-
-`-o FILE'
- Write output to FILE. This is the same as specifying FILE as the
- second non-option argument to `cpp'. `gcc' has a different
- interpretation of a second non-option argument, so you must use
- `-o' to specify the output file.
-
-`-Wall'
- Turns on all optional warnings which are desirable for normal
- code. At present this is `-Wcomment' and `-Wtrigraphs'. Note that
- many of the preprocessor's warnings are on by default and have no
- options to control them.
-
-`-Wcomment'
-`-Wcomments'
- Warn whenever a comment-start sequence `/*' appears in a `/*'
- comment, or whenever a backslash-newline appears in a `//' comment.
- (Both forms have the same effect.)
-
-`-Wtrigraphs'
- Warn if any trigraphs are encountered. This option used to take
- effect only if `-trigraphs' was also specified, but now works
- independently. Warnings are not given for trigraphs within
- comments, as they do not affect the meaning of the program.
-
-`-Wtraditional'
- Warn about certain constructs that behave differently in
- traditional and ISO C. Also warn about ISO C constructs that have
- no traditional C equivalent, and problematic constructs which
- should be avoided. *Note Traditional Mode::.
-
-`-Wimport'
- Warn the first time `#import' is used.
-
-`-Wundef'
- Warn whenever an identifier which is not a macro is encountered in
- an `#if' directive, outside of `defined'. Such identifiers are
- replaced with zero.
-
-`-Werror'
- Make all warnings into hard errors. Source code which triggers
- warnings will be rejected.
-
-`-Wsystem-headers'
- Issue warnings for code in system headers. These are normally
- unhelpful in finding bugs in your own code, therefore suppressed.
- If you are responsible for the system library, you may want to see
- them.
-
-`-w'
- Suppress all warnings, including those which GNU CPP issues by
- default.
-
-`-pedantic'
- Issue all the mandatory diagnostics listed in the C standard.
- Some of them are left out by default, since they trigger
- frequently on harmless code.
-
-`-pedantic-errors'
- Issue all the mandatory diagnostics, and make all mandatory
- diagnostics into errors. This includes mandatory diagnostics that
- GCC issues without `-pedantic' but treats as warnings.
-
-`-M'
- Instead of outputting the result of preprocessing, output a rule
- suitable for `make' describing the dependencies of the main source
- file. The preprocessor outputs one `make' rule containing the
- object file name for that source file, a colon, and the names of
- all the included files, including those coming from `-include' or
- `-imacros' command line options.
-
- Unless specified explicitly (with `-MT' or `-MQ'), the object file
- name consists of the basename of the source file with any suffix
- replaced with object file suffix. If there are many included
- files then the rule is split into several lines using `\'-newline.
- The rule has no commands.
-
- This option does not suppress the preprocessor's debug output,
- such as `-dM'. To avoid mixing such debug output with the
- dependency rules you should explicitly specify the dependency
- output file with `-MF', or use an environment variable like
- `DEPENDENCIES_OUTPUT' (*note DEPENDENCIES_OUTPUT::). Debug output
- will still be sent to the regular output stream as normal.
-
- Passing `-M' to the driver implies `-E'.
-
-`-MM'
- Like `-M' but do not mention header files that are found in system
- header directories, nor header files that are included, directly
- or indirectly, from such a header.
-
- This implies that the choice of angle brackets or double quotes in
- an `#include' directive does not in itself determine whether that
- header will appear in `-MM' dependency output. This is a slight
- change in semantics from GCC versions 3.0 and earlier.
-
-`-MF FILE'
- When used with `-M' or `-MM', specifies a file to write the
- dependencies to. If no `-MF' switch is given the preprocessor
- sends the rules to the same place it would have sent preprocessed
- output.
-
- When used with the driver options `-MD' or `-MMD', `-MF' overrides
- the default dependency output file.
-
-`-MG'
- When used with `-M' or `-MM', `-MG' says to treat missing header
- files as generated files and assume they live in the same
- directory as the source file. It suppresses preprocessed output,
- as a missing header file is ordinarily an error.
-
- This feature is used in automatic updating of makefiles.
-
-`-MP'
- This option instructs CPP to add a phony target for each dependency
- other than the main file, causing each to depend on nothing. These
- dummy rules work around errors `make' gives if you remove header
- files without updating the `Makefile' to match.
-
- This is typical output:
-
- test.o: test.c test.h
-
- test.h:
-
-`-MT TARGET'
- Change the target of the rule emitted by dependency generation. By
- default CPP takes the name of the main input file, including any
- path, deletes any file suffix such as `.c', and appends the
- platform's usual object suffix. The result is the target.
-
- An `-MT' option will set the target to be exactly the string you
- specify. If you want multiple targets, you can specify them as a
- single argument to `-MT', or use multiple `-MT' options.
-
- For example, `-MT '$(objpfx)foo.o'' might give
-
- $(objpfx)foo.o: foo.c
-
-`-MQ TARGET'
- Same as `-MT', but it quotes any characters which are special to
- Make. `-MQ '$(objpfx)foo.o'' gives
-
- $$(objpfx)foo.o: foo.c
-
- The default target is automatically quoted, as if it were given
- with `-MQ'.
-
-`-MD'
- `-MD' is equivalent to `-M -MF FILE', except that `-E' is not
- implied. The driver determines FILE based on whether an `-o'
- option is given. If it is, the driver uses its argument but with
- a suffix of `.d', otherwise it take the basename of the input file
- and applies a `.d' suffix.
-
- If `-MD' is used in conjunction with `-E', any `-o' switch is
- understood to specify the dependency output file (but *note
- -MF::), but if used without `-E', each `-o' is understood to
- specify a target object file.
-
- Since `-E' is not implied, `-MD' can be used to generate a
- dependency output file as a side-effect of the compilation process.
-
-`-MMD'
- Like `-MD' except mention only user header files, not system
- -header files.
-
-`-x c'
-`-x c++'
-`-x objective-c'
-`-x assembler-with-cpp'
- Specify the source language: C, C++, Objective-C, or assembly.
- This has nothing to do with standards conformance or extensions;
- it merely selects which base syntax to expect. If you give none
- of these options, cpp will deduce the language from the extension
- of the source file: `.c', `.cc', `.m', or `.S'. Some other common
- extensions for C++ and assembly are also recognized. If cpp does
- not recognize the extension, it will treat the file as C; this is
- the most generic mode.
-
- *Note:* Previous versions of cpp accepted a `-lang' option which
- selected both the language and the standards conformance level.
- This option has been removed, because it conflicts with the `-l'
- option.
-
-`-std=STANDARD'
-`-ansi'
- Specify the standard to which the code should conform. Currently
- cpp only knows about the standards for C; other language standards
- will be added in the future.
-
- STANDARD may be one of:
- `iso9899:1990'
- `c89'
- The ISO C standard from 1990. `c89' is the customary
- shorthand for this version of the standard.
-
- The `-ansi' option is equivalent to `-std=c89'.
-
- `iso9899:199409'
- The 1990 C standard, as amended in 1994.
-
- `iso9899:1999'
- `c99'
- `iso9899:199x'
- `c9x'
- The revised ISO C standard, published in December 1999.
- Before publication, this was known as C9X.
-
- `gnu89'
- The 1990 C standard plus GNU extensions. This is the default.
-
- `gnu99'
- `gnu9x'
- The 1999 C standard plus GNU extensions.
-
-`-I-'
- Split the include path. Any directories specified with `-I'
- options before `-I-' are searched only for headers requested with
- `#include "FILE"'; they are not searched for `#include <FILE>'.
- If additional directories are specified with `-I' options after
- the `-I-', those directories are searched for all `#include'
- directives.
-
- In addition, `-I-' inhibits the use of the directory of the current
- file directory as the first search directory for `#include "FILE"'.
- *Note Search Path::.
-
-`-nostdinc'
- Do not search the standard system directories for header files.
- Only the directories you have specified with `-I' options (and the
- directory of the current file, if appropriate) are searched.
-
-`-nostdinc++'
- Do not search for header files in the C++-specific standard
- directories, but do still search the other standard directories.
- (This option is used when building the C++ library.)
-
-`-include FILE'
- Process FILE as if `#include "file"' appeared as the first line of
- the primary source file. However, the first directory searched
- for FILE is the preprocessor's working directory _instead of_ the
- directory containing the main source file. If not found there, it
- is searched for in the remainder of the `#include "..."' search
- chain as normal.
-
- If multiple `-include' options are given, the files are included
- in the order they appear on the command line.
-
-`-imacros FILE'
- Exactly like `-include', except that any output produced by
- scanning FILE is thrown away. Macros it defines remain defined.
- This allows you to acquire all the macros from a header without
- also processing its declarations.
-
- All files specified by `-imacros' are processed before all files
- specified by `-include'.
-
-`-idirafter DIR'
- Search DIR for header files, but do it _after_ all directories
- specified with `-I' and the standard system directories have been
- exhausted. DIR is treated as a system include directory.
-
-`-iprefix PREFIX'
- Specify PREFIX as the prefix for subsequent `-iwithprefix'
- options. If the prefix represents a directory, you should include
- the final `/'.
-
-`-iwithprefix DIR'
-`-iwithprefixbefore DIR'
- Append DIR to the prefix specified previously with `-iprefix', and
- add the resulting directory to the include search path.
- `-iwithprefixbefore' puts it in the same place `-I' would;
- `-iwithprefix' puts it where `-idirafter' would.
-
- Use of these options is discouraged.
-
-`-isystem DIR'
- Search DIR for header files, after all directories specified by
- `-I' but before the standard system directories. Mark it as a
- system directory, so that it gets the same special treatment as is
- applied to the standard system directories. *Note System
- Headers::.
-
-`-fpreprocessed'
- Indicate to the preprocessor that the input file has already been
- preprocessed. This suppresses things like macro expansion,
- trigraph conversion, escaped newline splicing, and processing of
- most directives. The preprocessor still recognizes and removes
- comments, so that you can pass a file preprocessed with `-C' to
- the compiler without problems. In this mode the integrated
- preprocessor is little more than a tokenizer for the front ends.
-
- `-fpreprocessed' is implicit if the input file has one of the
- extensions `.i', `.ii' or `.mi'. These are the extensions that
- GCC uses for preprocessed files created by `-save-temps'.
-
-`-ftabstop=WIDTH'
- Set the distance between tab stops. This helps the preprocessor
- report correct column numbers in warnings or errors, even if tabs
- appear on the line. If the value is less than 1 or greater than
- 100, the option is ignored. The default is 8.
-
-`-fno-show-column'
- Do not print column numbers in diagnostics. This may be necessary
- if diagnostics are being scanned by a program that does not
- understand the column numbers, such as `dejagnu'.
-
-`-A PREDICATE=ANSWER'
- Make an assertion with the predicate PREDICATE and answer ANSWER.
- This form is preferred to the older form `-A PREDICATE(ANSWER)',
- which is still supported, because it does not use shell special
- characters. *Note Assertions::.
-
-`-A -PREDICATE=ANSWER'
- Cancel an assertion with the predicate PREDICATE and answer ANSWER.
-
-`-A-'
- Cancel all predefined assertions and all assertions preceding it on
- the command line. Also, undefine all predefined macros and all
- macros preceding it on the command line. (This is a historical
- wart and may change in the future.)
-
-`-dCHARS'
- CHARS is a sequence of one or more of the following characters,
- and must not be preceded by a space. Other characters are
- interpreted by the compiler proper, or reserved for future
- versions of GCC, and so are silently ignored. If you specify
- characters whose behavior conflicts, the result is undefined.
-
- `M'
- Instead of the normal output, generate a list of `#define'
- directives for all the macros defined during the execution of
- the preprocessor, including predefined macros. This gives
- you a way of finding out what is predefined in your version
- of the preprocessor. Assuming you have no file `foo.h', the
- command
-
- touch foo.h; cpp -dM foo.h
-
- will show all the predefined macros.
-
- `D'
- Like `M' except in two respects: it does _not_ include the
- predefined macros, and it outputs _both_ the `#define'
- directives and the result of preprocessing. Both kinds of
- output go to the standard output file.
-
- `N'
- Like `D', but emit only the macro names, not their expansions.
-
- `I'
- Output `#include' directives in addition to the result of
- preprocessing.
-
-`-P'
- Inhibit generation of linemarkers in the output from the
- preprocessor. This might be useful when running the preprocessor
- on something that is not C code, and will be sent to a program
- which might be confused by the linemarkers. *Note Preprocessor
- Output::.
-
-`-C'
- Do not discard comments. All comments are passed through to the
- output file, except for comments in processed directives, which
- are deleted along with the directive.
-
- You should be prepared for side effects when using `-C'; it causes
- the preprocessor to treat comments as tokens in their own right.
- For example, comments appearing at the start of what would be a
- directive line have the effect of turning that line into an
- ordinary source line, since the first token on the line is no
- longer a `#'.
-
-`-gcc'
- Define the macros __GNUC__, __GNUC_MINOR__ and
- __GNUC_PATCHLEVEL__. These are defined automatically when you use
- `gcc -E'; you can turn them off in that case with `-no-gcc'.
-
-`-traditional'
- Try to imitate the behavior of old-fashioned C, as opposed to ISO
- C. *Note Traditional Mode::.
-
-`-trigraphs'
- Process trigraph sequences. *Note Initial processing::.
-
-`-remap'
- Enable special code to work around file systems which only permit
- very short file names, such as MS-DOS.
-
-`-$'
- Forbid the use of `$' in identifiers. The C standard allows
- implementations to define extra characters that can appear in
- identifiers. By default GNU CPP permits `$', a common extension.
-
-`-h'
-`--help'
-`--target-help'
- Print text describing all the command line options instead of
- preprocessing anything.
-
-`-v'
- Verbose mode. Print out GNU CPP's version number at the beginning
- of execution, and report the final form of the include path.
-
-`-H'
- Print the name of each header file used, in addition to other
- normal activities. Each name is indented to show how deep in the
- `#include' stack it is.
-
-`-version'
-`--version'
- Print out GNU CPP's version number. With one dash, proceed to
- preprocess as normal. With two dashes, exit immediately.
-
-\1f
-File: cpp.info, Node: Environment Variables, Next: GNU Free Documentation License, Prev: Invocation, Up: Top
-
-Environment Variables
-*********************
-
- This section describes the environment variables that affect how CPP
-operates. You can use them to specify directories or prefixes to use
-when searching for include files, or to control dependency output.
-
- Note that you can also specify places to search using options such as
-`-I', and control dependency output with options like `-M' (*note
-Invocation::). These take precedence over environment variables, which
-in turn take precedence over the configuration of GCC.
-
-`CPATH'
-`C_INCLUDE_PATH'
-`CPLUS_INCLUDE_PATH'
-`OBJC_INCLUDE_PATH'
- Each variable's value is a list of directories separated by a
- special character, much like `PATH', in which to look for header
- files. The special character, `PATH_SEPARATOR', is
- target-dependent and determined at GCC build time. For
- Windows-based targets it is a semicolon, and for almost all other
- targets it is a colon.
-
- `CPATH' specifies a list of directories to be searched as if
- specified with `-I', but after any paths given with `-I' options
- on the command line. The environment variable is used regardless
- of which language is being preprocessed.
-
- The remaining environment variables apply only when preprocessing
- the particular language indicated. Each specifies a list of
- directories to be searched as if specified with `-isystem', but
- after any paths given with `-isystem' options on the command line.
-
- See also *Note Search Path::.
-
-`DEPENDENCIES_OUTPUT'
- If this variable is set, its value specifies how to output
- dependencies for Make based on the non-system header files
- processed by the compiler. System header files are ignored in the
- dependency output.
-
- The value of `DEPENDENCIES_OUTPUT' can be just a file name, in
- which case the Make rules are written to that file, guessing the
- target name from the source file name. Or the value can have the
- form `FILE TARGET', in which case the rules are written to file
- FILE using TARGET as the target name.
-
- In other words, this environment variable is equivalent to
- combining the options `-MM' and `-MF' (*note Invocation::), with
- an optional `-MT' switch too.
-
-`SUNPRO_DEPENDENCIES'
- This variable is the same as the environment variable
- `DEPENDENCIES_OUTPUT' (*note DEPENDENCIES_OUTPUT::), except that
- system header files are not ignored, so it implies `-M' rather
- than `-MM'. However, the dependence on the main input file is
- omitted. *Note Invocation::.
-
-\1f
-File: cpp.info, Node: GNU Free Documentation License, Next: Option Index, Prev: Environment Variables, Up: Top
-
-GNU Free Documentation License
-******************************
-
- Version 1.1, March 2000
- Copyright (C) 2000 Free Software Foundation, Inc.
- 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
-
- Everyone is permitted to copy and distribute verbatim copies
- of this license document, but changing it is not allowed.
-
- 0. PREAMBLE
-
- The purpose of this License is to make a manual, textbook, or other
- written document "free" in the sense of freedom: to assure everyone
- the effective freedom to copy and redistribute it, with or without
- modifying it, either commercially or noncommercially. Secondarily,
- this License preserves for the author and publisher a way to get
- credit for their work, while not being considered responsible for
- modifications made by others.
-
- This License is a kind of "copyleft", which means that derivative
- works of the document must themselves be free in the same sense.
- It complements the GNU General Public License, which is a copyleft
- license designed for free software.
-
- We have designed this License in order to use it for manuals for
- free software, because free software needs free documentation: a
- free program should come with manuals providing the same freedoms
- that the software does. But this License is not limited to
- software manuals; it can be used for any textual work, regardless
- of subject matter or whether it is published as a printed book.
- We recommend this License principally for works whose purpose is
- instruction or reference.
-
- 1. APPLICABILITY AND DEFINITIONS
-
- This License applies to any manual or other work that contains a
- notice placed by the copyright holder saying it can be distributed
- under the terms of this License. The "Document", below, refers to
- any such manual or work. Any member of the public is a licensee,
- and is addressed as "you".
-
- A "Modified Version" of the Document means any work containing the
- Document or a portion of it, either copied verbatim, or with
- modifications and/or translated into another language.
-
- A "Secondary Section" is a named appendix or a front-matter
- section of the Document that deals exclusively with the
- relationship of the publishers or authors of the Document to the
- Document's overall subject (or to related matters) and contains
- nothing that could fall directly within that overall subject.
- (For example, if the Document is in part a textbook of
- mathematics, a Secondary Section may not explain any mathematics.)
- The relationship could be a matter of historical connection with
- the subject or with related matters, or of legal, commercial,
- philosophical, ethical or political position regarding them.
-
- The "Invariant Sections" are certain Secondary Sections whose
- titles are designated, as being those of Invariant Sections, in
- the notice that says that the Document is released under this
- License.
-
- The "Cover Texts" are certain short passages of text that are
- listed, as Front-Cover Texts or Back-Cover Texts, in the notice
- that says that the Document is released under this License.
-
- A "Transparent" copy of the Document means a machine-readable copy,
- represented in a format whose specification is available to the
- general public, whose contents can be viewed and edited directly
- and straightforwardly with generic text editors or (for images
- composed of pixels) generic paint programs or (for drawings) some
- widely available drawing editor, and that is suitable for input to
- text formatters or for automatic translation to a variety of
- formats suitable for input to text formatters. A copy made in an
- otherwise Transparent file format whose markup has been designed
- to thwart or discourage subsequent modification by readers is not
- Transparent. A copy that is not "Transparent" is called "Opaque".
-
- Examples of suitable formats for Transparent copies include plain
- ASCII without markup, Texinfo input format, LaTeX input format,
- SGML or XML using a publicly available DTD, and
- standard-conforming simple HTML designed for human modification.
- Opaque formats include PostScript, PDF, proprietary formats that
- can be read and edited only by proprietary word processors, SGML
- or XML for which the DTD and/or processing tools are not generally
- available, and the machine-generated HTML produced by some word
- processors for output purposes only.
-
- The "Title Page" means, for a printed book, the title page itself,
- plus such following pages as are needed to hold, legibly, the
- material this License requires to appear in the title page. For
- works in formats which do not have any title page as such, "Title
- Page" means the text near the most prominent appearance of the
- work's title, preceding the beginning of the body of the text.
-
- 2. VERBATIM COPYING
-
- You may copy and distribute the Document in any medium, either
- commercially or noncommercially, provided that this License, the
- copyright notices, and the license notice saying this License
- applies to the Document are reproduced in all copies, and that you
- add no other conditions whatsoever to those of this License. You
- may not use technical measures to obstruct or control the reading
- or further copying of the copies you make or distribute. However,
- you may accept compensation in exchange for copies. If you
- distribute a large enough number of copies you must also follow
- the conditions in section 3.
-
- You may also lend copies, under the same conditions stated above,
- and you may publicly display copies.
-
- 3. COPYING IN QUANTITY
-
- If you publish printed copies of the Document numbering more than
- 100, and the Document's license notice requires Cover Texts, you
- must enclose the copies in covers that carry, clearly and legibly,
- all these Cover Texts: Front-Cover Texts on the front cover, and
- Back-Cover Texts on the back cover. Both covers must also clearly
- and legibly identify you as the publisher of these copies. The
- front cover must present the full title with all words of the
- title equally prominent and visible. You may add other material
- on the covers in addition. Copying with changes limited to the
- covers, as long as they preserve the title of the Document and
- satisfy these conditions, can be treated as verbatim copying in
- other respects.
-
- If the required texts for either cover are too voluminous to fit
- legibly, you should put the first ones listed (as many as fit
- reasonably) on the actual cover, and continue the rest onto
- adjacent pages.
-
- If you publish or distribute Opaque copies of the Document
- numbering more than 100, you must either include a
- machine-readable Transparent copy along with each Opaque copy, or
- state in or with each Opaque copy a publicly-accessible
- computer-network location containing a complete Transparent copy
- of the Document, free of added material, which the general
- network-using public has access to download anonymously at no
- charge using public-standard network protocols. If you use the
- latter option, you must take reasonably prudent steps, when you
- begin distribution of Opaque copies in quantity, to ensure that
- this Transparent copy will remain thus accessible at the stated
- location until at least one year after the last time you
- distribute an Opaque copy (directly or through your agents or
- retailers) of that edition to the public.
-
- It is requested, but not required, that you contact the authors of
- the Document well before redistributing any large number of
- copies, to give them a chance to provide you with an updated
- version of the Document.
-
- 4. MODIFICATIONS
-
- You may copy and distribute a Modified Version of the Document
- under the conditions of sections 2 and 3 above, provided that you
- release the Modified Version under precisely this License, with
- the Modified Version filling the role of the Document, thus
- licensing distribution and modification of the Modified Version to
- whoever possesses a copy of it. In addition, you must do these
- things in the Modified Version:
-
- A. Use in the Title Page (and on the covers, if any) a title
- distinct from that of the Document, and from those of
- previous versions (which should, if there were any, be listed
- in the History section of the Document). You may use the
- same title as a previous version if the original publisher of
- that version gives permission.
-
- B. List on the Title Page, as authors, one or more persons or
- entities responsible for authorship of the modifications in
- the Modified Version, together with at least five of the
- principal authors of the Document (all of its principal
- authors, if it has less than five).
-
- C. State on the Title page the name of the publisher of the
- Modified Version, as the publisher.
-
- D. Preserve all the copyright notices of the Document.
-
- E. Add an appropriate copyright notice for your modifications
- adjacent to the other copyright notices.
-
- F. Include, immediately after the copyright notices, a license
- notice giving the public permission to use the Modified
- Version under the terms of this License, in the form shown in
- the Addendum below.
-
- G. Preserve in that license notice the full lists of Invariant
- Sections and required Cover Texts given in the Document's
- license notice.
-
- H. Include an unaltered copy of this License.
-
- I. Preserve the section entitled "History", and its title, and
- add to it an item stating at least the title, year, new
- authors, and publisher of the Modified Version as given on
- the Title Page. If there is no section entitled "History" in
- the Document, create one stating the title, year, authors,
- and publisher of the Document as given on its Title Page,
- then add an item describing the Modified Version as stated in
- the previous sentence.
-
- J. Preserve the network location, if any, given in the Document
- for public access to a Transparent copy of the Document, and
- likewise the network locations given in the Document for
- previous versions it was based on. These may be placed in
- the "History" section. You may omit a network location for a
- work that was published at least four years before the
- Document itself, or if the original publisher of the version
- it refers to gives permission.
-
- K. In any section entitled "Acknowledgments" or "Dedications",
- preserve the section's title, and preserve in the section all
- the substance and tone of each of the contributor
- acknowledgments and/or dedications given therein.
-
- L. Preserve all the Invariant Sections of the Document,
- unaltered in their text and in their titles. Section numbers
- or the equivalent are not considered part of the section
- titles.
-
- M. Delete any section entitled "Endorsements". Such a section
- may not be included in the Modified Version.
-
- N. Do not retitle any existing section as "Endorsements" or to
- conflict in title with any Invariant Section.
-
- If the Modified Version includes new front-matter sections or
- appendices that qualify as Secondary Sections and contain no
- material copied from the Document, you may at your option
- designate some or all of these sections as invariant. To do this,
- add their titles to the list of Invariant Sections in the Modified
- Version's license notice. These titles must be distinct from any
- other section titles.
-
- You may add a section entitled "Endorsements", provided it contains
- nothing but endorsements of your Modified Version by various
- parties--for example, statements of peer review or that the text
- has been approved by an organization as the authoritative
- definition of a standard.
-
- You may add a passage of up to five words as a Front-Cover Text,
- and a passage of up to 25 words as a Back-Cover Text, to the end
- of the list of Cover Texts in the Modified Version. Only one
- passage of Front-Cover Text and one of Back-Cover Text may be
- added by (or through arrangements made by) any one entity. If the
- Document already includes a cover text for the same cover,
- previously added by you or by arrangement made by the same entity
- you are acting on behalf of, you may not add another; but you may
- replace the old one, on explicit permission from the previous
- publisher that added the old one.
-
- The author(s) and publisher(s) of the Document do not by this
- License give permission to use their names for publicity for or to
- assert or imply endorsement of any Modified Version.
-
- 5. COMBINING DOCUMENTS
-
- You may combine the Document with other documents released under
- this License, under the terms defined in section 4 above for
- modified versions, provided that you include in the combination
- all of the Invariant Sections of all of the original documents,
- unmodified, and list them all as Invariant Sections of your
- combined work in its license notice.
-
- The combined work need only contain one copy of this License, and
- multiple identical Invariant Sections may be replaced with a single
- copy. If there are multiple Invariant Sections with the same name
- but different contents, make the title of each such section unique
- by adding at the end of it, in parentheses, the name of the
- original author or publisher of that section if known, or else a
- unique number. Make the same adjustment to the section titles in
- the list of Invariant Sections in the license notice of the
- combined work.
-
- In the combination, you must combine any sections entitled
- "History" in the various original documents, forming one section
- entitled "History"; likewise combine any sections entitled
- "Acknowledgments", and any sections entitled "Dedications". You
- must delete all sections entitled "Endorsements."
-
- 6. COLLECTIONS OF DOCUMENTS
-
- You may make a collection consisting of the Document and other
- documents released under this License, and replace the individual
- copies of this License in the various documents with a single copy
- that is included in the collection, provided that you follow the
- rules of this License for verbatim copying of each of the
- documents in all other respects.
-
- You may extract a single document from such a collection, and
- distribute it individually under this License, provided you insert
- a copy of this License into the extracted document, and follow
- this License in all other respects regarding verbatim copying of
- that document.
-
- 7. AGGREGATION WITH INDEPENDENT WORKS
-
- A compilation of the Document or its derivatives with other
- separate and independent documents or works, in or on a volume of
- a storage or distribution medium, does not as a whole count as a
- Modified Version of the Document, provided no compilation
- copyright is claimed for the compilation. Such a compilation is
- called an "aggregate", and this License does not apply to the
- other self-contained works thus compiled with the Document, on
- account of their being thus compiled, if they are not themselves
- derivative works of the Document.
-
- If the Cover Text requirement of section 3 is applicable to these
- copies of the Document, then if the Document is less than one
- quarter of the entire aggregate, the Document's Cover Texts may be
- placed on covers that surround only the Document within the
- aggregate. Otherwise they must appear on covers around the whole
- aggregate.
-
- 8. TRANSLATION
-
- Translation is considered a kind of modification, so you may
- distribute translations of the Document under the terms of section
- 4. Replacing Invariant Sections with translations requires special
- permission from their copyright holders, but you may include
- translations of some or all Invariant Sections in addition to the
- original versions of these Invariant Sections. You may include a
- translation of this License provided that you also include the
- original English version of this License. In case of a
- disagreement between the translation and the original English
- version of this License, the original English version will prevail.
-
- 9. TERMINATION
-
- You may not copy, modify, sublicense, or distribute the Document
- except as expressly provided for under this License. Any other
- attempt to copy, modify, sublicense or distribute the Document is
- void, and will automatically terminate your rights under this
- License. However, parties who have received copies, or rights,
- from you under this License will not have their licenses
- terminated so long as such parties remain in full compliance.
-
- 10. FUTURE REVISIONS OF THIS LICENSE
-
- The Free Software Foundation may publish new, revised versions of
- the GNU Free Documentation License from time to time. Such new
- versions will be similar in spirit to the present version, but may
- differ in detail to address new problems or concerns. See
- `http://www.gnu.org/copyleft/'.
-
- Each version of the License is given a distinguishing version
- number. If the Document specifies that a particular numbered
- version of this License "or any later version" applies to it, you
- have the option of following the terms and conditions either of
- that specified version or of any later version that has been
- published (not as a draft) by the Free Software Foundation. If
- the Document does not specify a version number of this License,
- you may choose any version ever published (not as a draft) by the
- Free Software Foundation.
-
-ADDENDUM: How to use this License for your documents
-====================================================
-
- To use this License in a document you have written, include a copy of
-the License in the document and put the following copyright and license
-notices just after the title page:
-
- Copyright (C) YEAR YOUR NAME.
- Permission is granted to copy, distribute and/or modify this document
- under the terms of the GNU Free Documentation License, Version 1.1
- or any later version published by the Free Software Foundation;
- with the Invariant Sections being LIST THEIR TITLES, with the
- Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
- A copy of the license is included in the section entitled ``GNU
- Free Documentation License''.
-
- If you have no Invariant Sections, write "with no Invariant Sections"
-instead of saying which ones are invariant. If you have no Front-Cover
-Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being
-LIST"; likewise for Back-Cover Texts.
-
- If your document contains nontrivial examples of program code, we
-recommend releasing these examples in parallel under your choice of
-free software license, such as the GNU General Public License, to
-permit their use in free software.
-
-\1f
-File: cpp.info, Node: Option Index, Next: Index of Directives, Prev: GNU Free Documentation License, Up: Top
-
-Option Index
-************
-
- CPP's command line options are indexed here without any initial `-'
-or `--'.
-
-* Menu:
-
-* $: Invocation.
-* A: Invocation.
-* A-: Invocation.
-* ansi: Invocation.
-* C: Invocation.
-* D: Invocation.
-* dD: Invocation.
-* dI: Invocation.
-* dM: Invocation.
-* dN: Invocation.
-* fno-show-column: Invocation.
-* fpreprocessed: Invocation.
-* ftabstop: Invocation.
-* gcc: Invocation.
-* H: Invocation.
-* h: Invocation.
-* help: Invocation.
-* I: Invocation.
-* I-: Invocation.
-* idirafter: Invocation.
-* imacros: Invocation.
-* include: Invocation.
-* iprefix: Invocation.
-* isystem: Invocation.
-* iwithprefix: Invocation.
-* iwithprefixbefore: Invocation.
-* M: Invocation.
-* MD: Invocation.
-* MF: Invocation.
-* MG: Invocation.
-* MM: Invocation.
-* MMD: Invocation.
-* MP: Invocation.
-* MQ: Invocation.
-* MT: Invocation.
-* nostdinc: Invocation.
-* nostdinc++: Invocation.
-* o: Invocation.
-* P: Invocation.
-* pedantic: Invocation.
-* pedantic-errors: Invocation.
-* remap: Invocation.
-* std=: Invocation.
-* target-help: Invocation.
-* traditional: Invocation.
-* trigraphs: Invocation.
-* U: Invocation.
-* undef: Invocation.
-* v: Invocation.
-* version: Invocation.
-* w: Invocation.
-* Wall: Invocation.
-* Wcomment: Invocation.
-* Wcomments: Invocation.
-* Werror: Invocation.
-* Wimport: Invocation.
-* Wsystem-headers: Invocation.
-* Wtraditional: Invocation.
-* Wtrigraphs: Invocation.
-* Wundef: Invocation.
-* x: Invocation.
-
-\1f
-File: cpp.info, Node: Index of Directives, Next: Concept Index, Prev: Option Index, Up: Top
-
-Index of Directives
-*******************
-
-* Menu:
-
-* #assert: Assertions.
-* #define: Object-like Macros.
-* #elif: Elif.
-* #else: Else.
-* #endif: Ifdef.
-* #error: Diagnostics.
-* #ident: Other Directives.
-* #if: Conditional Syntax.
-* #ifdef: Ifdef.
-* #ifndef: Ifdef.
-* #import: Obsolete once-only headers.
-* #include: Include Syntax.
-* #include_next: Wrapper Headers.
-* #line: Line Control.
-* #pragma GCC dependency: Pragmas.
-* #pragma GCC poison: Pragmas.
-* #pragma GCC system_header <1>: Pragmas.
-* #pragma GCC system_header: System Headers.
-* #sccs: Other Directives.
-* #unassert: Assertions.
-* #undef: Undefining and Redefining Macros.
-* #warning: Diagnostics.
-* C_INCLUDE_PATH: Environment Variables.
-* CPATH: Environment Variables.
-* CPLUS_INCLUDE_PATH: Environment Variables.
-* DEPENDENCIES_OUTPUT: Environment Variables.
-* OBJC_INCLUDE_PATH: Environment Variables.
-* SUNPRO_DEPENDENCIES: Environment Variables.
-
+++ /dev/null
-This is doc/cpp.info, produced by makeinfo version 4.5 from
-doc/cpp.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* Cpp: (cpp). The GNU C preprocessor.
-END-INFO-DIR-ENTRY
-
-\1f
-File: cpp.info, Node: Concept Index, Prev: Index of Directives, Up: Top
-
-Concept Index
-*************
-
-* Menu:
-
-* # operator: Stringification.
-* ## operator: Concatenation.
-* _Pragma: Pragmas.
-* alternative tokens: Tokenization.
-* arguments: Macro Arguments.
-* arguments in macro definitions: Macro Arguments.
-* assertions: Assertions.
-* assertions, cancelling: Assertions.
-* backslash-newline: Initial processing.
-* block comments: Initial processing.
-* C++ named operators: C++ Named Operators.
-* character constants: Tokenization.
-* character sets: Initial processing.
-* command line: Invocation.
-* commenting out code: Deleted Code.
-* comments: Initial processing.
-* common predefined macros: Common Predefined Macros.
-* computed includes: Computed Includes.
-* concatenation: Concatenation.
-* conditional group: Ifdef.
-* conditionals: Conditionals.
-* continued lines: Initial processing.
-* controlling macro: Once-Only Headers.
-* defined: Defined.
-* dependencies for make as output: Environment Variables.
-* dependencies, make: Invocation.
-* diagnostic: Diagnostics.
-* differences from previous versions: Differences from previous versions.
-* digraphs: Tokenization.
-* directive line: The preprocessing language.
-* directive name: The preprocessing language.
-* directives: The preprocessing language.
-* empty macro arguments: Macro Arguments.
-* environment variables: Environment Variables.
-* expansion of arguments: Argument Prescan.
-* FDL, GNU Free Documentation License: GNU Free Documentation License.
-* function-like macros: Function-like Macros.
-* grouping options: Invocation.
-* guard macro: Once-Only Headers.
-* header file: Header Files.
-* header file names: Tokenization.
-* identifiers: Tokenization.
-* implementation limits: Implementation limits.
-* implementation-defined behavior: Implementation-defined behavior.
-* including just once: Once-Only Headers.
-* invalid token paste: Miscellaneous obsolete features.
-* invocation: Invocation.
-* iso646.h: C++ Named Operators.
-* line comments: Initial processing.
-* line control: Line Control.
-* line endings: Initial processing.
-* linemarkers: Preprocessor Output.
-* macro argument expansion: Argument Prescan.
-* macros in include: Computed Includes.
-* macros with arguments: Macro Arguments.
-* macros with variable arguments: Variadic Macros.
-* make: Invocation.
-* manifest constants: Object-like Macros.
-* multi-line string constants: Miscellaneous obsolete features.
-* named operators: C++ Named Operators.
-* newlines in macro arguments: Newlines in Arguments.
-* null directive: Other Directives.
-* numbers: Tokenization.
-* object-like macro: Object-like Macros.
-* options: Invocation.
-* options, grouping: Invocation.
-* other tokens: Tokenization.
-* output format: Preprocessor Output.
-* overriding a header file: Wrapper Headers.
-* parentheses in macro bodies: Operator Precedence Problems.
-* pitfalls of macros: Macro Pitfalls.
-* pragma poison: Miscellaneous obsolete features.
-* predefined macros: Predefined Macros.
-* predefined macros, system-specific: System-specific Predefined Macros.
-* predicates: Assertions.
-* preprocessing directives: The preprocessing language.
-* preprocessing numbers: Tokenization.
-* preprocessing tokens: Tokenization.
-* prescan of macro arguments: Argument Prescan.
-* problems with macros: Macro Pitfalls.
-* punctuators: Tokenization.
-* redefining macros: Undefining and Redefining Macros.
-* repeated inclusion: Once-Only Headers.
-* reporting errors: Diagnostics.
-* reporting warnings: Diagnostics.
-* reserved namespace: System-specific Predefined Macros.
-* self-reference: Self-Referential Macros.
-* semicolons (after macro calls): Swallowing the Semicolon.
-* side effects (in macro arguments): Duplication of Side Effects.
-* standard predefined macros.: Standard Predefined Macros.
-* string constants: Tokenization.
-* string literals: Tokenization.
-* stringification: Stringification.
-* symbolic constants: Object-like Macros.
-* system header files <1>: System Headers.
-* system header files: Header Files.
-* system-specific predefined macros: System-specific Predefined Macros.
-* testing predicates: Assertions.
-* token concatenation: Concatenation.
-* token pasting: Concatenation.
-* tokens: Tokenization.
-* trigraphs: Initial processing.
-* undefining macros: Undefining and Redefining Macros.
-* unsafe macros: Duplication of Side Effects.
-* variable number of arguments: Variadic Macros.
-* variadic macros: Variadic Macros.
-* wrapper #ifndef: Once-Only Headers.
-* wrapper headers: Wrapper Headers.
-
-
+++ /dev/null
-This is doc/cppinternals.info, produced by makeinfo version 4.5 from
-doc/cppinternals.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* Cpplib: (cppinternals). Cpplib internals.
-END-INFO-DIR-ENTRY
-
- This file documents the internals of the GNU C Preprocessor.
-
- Copyright 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to make and distribute verbatim copies of this
-manual provided the copyright notice and this permission notice are
-preserved on all copies.
-
- Permission is granted to copy and distribute modified versions of
-this manual under the conditions for verbatim copying, provided also
-that the entire resulting derived work is distributed under the terms
-of a permission notice identical to this one.
-
- Permission is granted to copy and distribute translations of this
-manual into another language, under the above conditions for modified
-versions.
-
-\1f
-File: cppinternals.info, Node: Top, Next: Conventions, Up: (dir)
-
-
-
-Cpplib--the GNU C Preprocessor
-******************************
-
- The GNU C preprocessor in GCC 3.x has been completely rewritten. It
-is now implemented as a library, "cpplib", so it can be easily shared
-between a stand-alone preprocessor, and a preprocessor integrated with
-the C, C++ and Objective-C front ends. It is also available for use by
-other programs, though this is not recommended as its exposed interface
-has not yet reached a point of reasonable stability.
-
- The library has been written to be re-entrant, so that it can be used
-to preprocess many files simultaneously if necessary. It has also been
-written with the preprocessing token as the fundamental unit; the
-preprocessor in previous versions of GCC would operate on text strings
-as the fundamental unit.
-
- This brief manual documents the internals of cpplib, and explains
-some of the tricky issues. It is intended that, along with the
-comments in the source code, a reasonably competent C programmer should
-be able to figure out what the code is doing, and why things have been
-implemented the way they have.
-
-* Menu:
-
-* Conventions:: Conventions used in the code.
-* Lexer:: The combined C, C++ and Objective-C Lexer.
-* Hash Nodes:: All identifiers are entered into a hash table.
-* Macro Expansion:: Macro expansion algorithm.
-* Token Spacing:: Spacing and paste avoidance issues.
-* Line Numbering:: Tracking location within files.
-* Guard Macros:: Optimizing header files with guard macros.
-* Files:: File handling.
-* Index:: Index.
-
-\1f
-File: cppinternals.info, Node: Conventions, Next: Lexer, Prev: Top, Up: Top
-
-Conventions
-***********
-
- cpplib has two interfaces--one is exposed internally only, and the
-other is for both internal and external use.
-
- The convention is that functions and types that are exposed to
-multiple files internally are prefixed with `_cpp_', and are to be
-found in the file `cpphash.h'. Functions and types exposed to external
-clients are in `cpplib.h', and prefixed with `cpp_'. For historical
-reasons this is no longer quite true, but we should strive to stick to
-it.
-
- We are striving to reduce the information exposed in `cpplib.h' to
-the bare minimum necessary, and then to keep it there. This makes clear
-exactly what external clients are entitled to assume, and allows us to
-change internals in the future without worrying whether library clients
-are perhaps relying on some kind of undocumented implementation-specific
-behavior.
-
-\1f
-File: cppinternals.info, Node: Lexer, Next: Hash Nodes, Prev: Conventions, Up: Top
-
-The Lexer
-*********
-
-Overview
-========
-
- The lexer is contained in the file `cpplex.c'. It is a hand-coded
-lexer, and not implemented as a state machine. It can understand C, C++
-and Objective-C source code, and has been extended to allow reasonably
-successful preprocessing of assembly language. The lexer does not make
-an initial pass to strip out trigraphs and escaped newlines, but handles
-them as they are encountered in a single pass of the input file. It
-returns preprocessing tokens individually, not a line at a time.
-
- It is mostly transparent to users of the library, since the library's
-interface for obtaining the next token, `cpp_get_token', takes care of
-lexing new tokens, handling directives, and expanding macros as
-necessary. However, the lexer does expose some functionality so that
-clients of the library can easily spell a given token, such as
-`cpp_spell_token' and `cpp_token_len'. These functions are useful when
-generating diagnostics, and for emitting the preprocessed output.
-
-Lexing a token
-==============
-
- Lexing of an individual token is handled by `_cpp_lex_direct' and
-its subroutines. In its current form the code is quite complicated,
-with read ahead characters and such-like, since it strives to not step
-back in the character stream in preparation for handling non-ASCII file
-encodings. The current plan is to convert any such files to UTF-8
-before processing them. This complexity is therefore unnecessary and
-will be removed, so I'll not discuss it further here.
-
- The job of `_cpp_lex_direct' is simply to lex a token. It is not
-responsible for issues like directive handling, returning lookahead
-tokens directly, multiple-include optimization, or conditional block
-skipping. It necessarily has a minor ro^le to play in memory
-management of lexed lines. I discuss these issues in a separate section
-(*note Lexing a line::).
-
- The lexer places the token it lexes into storage pointed to by the
-variable `cur_token', and then increments it. This variable is
-important for correct diagnostic positioning. Unless a specific line
-and column are passed to the diagnostic routines, they will examine the
-`line' and `col' values of the token just before the location that
-`cur_token' points to, and use that location to report the diagnostic.
-
- The lexer does not consider whitespace to be a token in its own
-right. If whitespace (other than a new line) precedes a token, it sets
-the `PREV_WHITE' bit in the token's flags. Each token has its `line'
-and `col' variables set to the line and column of the first character
-of the token. This line number is the line number in the translation
-unit, and can be converted to a source (file, line) pair using the line
-map code.
-
- The first token on a logical, i.e. unescaped, line has the flag
-`BOL' set for beginning-of-line. This flag is intended for internal
-use, both to distinguish a `#' that begins a directive from one that
-doesn't, and to generate a call-back to clients that want to be
-notified about the start of every non-directive line with tokens on it.
-Clients cannot reliably determine this for themselves: the first token
-might be a macro, and the tokens of a macro expansion do not have the
-`BOL' flag set. The macro expansion may even be empty, and the next
-token on the line certainly won't have the `BOL' flag set.
-
- New lines are treated specially; exactly how the lexer handles them
-is context-dependent. The C standard mandates that directives are
-terminated by the first unescaped newline character, even if it appears
-in the middle of a macro expansion. Therefore, if the state variable
-`in_directive' is set, the lexer returns a `CPP_EOF' token, which is
-normally used to indicate end-of-file, to indicate end-of-directive.
-In a directive a `CPP_EOF' token never means end-of-file.
-Conveniently, if the caller was `collect_args', it already handles
-`CPP_EOF' as if it were end-of-file, and reports an error about an
-unterminated macro argument list.
-
- The C standard also specifies that a new line in the middle of the
-arguments to a macro is treated as whitespace. This white space is
-important in case the macro argument is stringified. The state variable
-`parsing_args' is nonzero when the preprocessor is collecting the
-arguments to a macro call. It is set to 1 when looking for the opening
-parenthesis to a function-like macro, and 2 when collecting the actual
-arguments up to the closing parenthesis, since these two cases need to
-be distinguished sometimes. One such time is here: the lexer sets the
-`PREV_WHITE' flag of a token if it meets a new line when `parsing_args'
-is set to 2. It doesn't set it if it meets a new line when
-`parsing_args' is 1, since then code like
-
- #define foo() bar
- foo
- baz
-
-would be output with an erroneous space before `baz':
-
- foo
- baz
-
- This is a good example of the subtlety of getting token spacing
-correct in the preprocessor; there are plenty of tests in the test
-suite for corner cases like this.
-
- The lexer is written to treat each of `\r', `\n', `\r\n' and `\n\r'
-as a single new line indicator. This allows it to transparently
-preprocess MS-DOS, Macintosh and Unix files without their needing to
-pass through a special filter beforehand.
-
- We also decided to treat a backslash, either `\' or the trigraph
-`??/', separated from one of the above newline indicators by
-non-comment whitespace only, as intending to escape the newline. It
-tends to be a typing mistake, and cannot reasonably be mistaken for
-anything else in any of the C-family grammars. Since handling it this
-way is not strictly conforming to the ISO standard, the library issues a
-warning wherever it encounters it.
-
- Handling newlines like this is made simpler by doing it in one place
-only. The function `handle_newline' takes care of all newline
-characters, and `skip_escaped_newlines' takes care of arbitrarily long
-sequences of escaped newlines, deferring to `handle_newline' to handle
-the newlines themselves.
-
- The most painful aspect of lexing ISO-standard C and C++ is handling
-trigraphs and backlash-escaped newlines. Trigraphs are processed before
-any interpretation of the meaning of a character is made, and
-unfortunately there is a trigraph representation for a backslash, so it
-is possible for the trigraph `??/' to introduce an escaped newline.
-
- Escaped newlines are tedious because theoretically they can occur
-anywhere--between the `+' and `=' of the `+=' token, within the
-characters of an identifier, and even between the `*' and `/' that
-terminates a comment. Moreover, you cannot be sure there is just
-one--there might be an arbitrarily long sequence of them.
-
- So, for example, the routine that lexes a number, `parse_number',
-cannot assume that it can scan forwards until the first non-number
-character and be done with it, because this could be the `\'
-introducing an escaped newline, or the `?' introducing the trigraph
-sequence that represents the `\' of an escaped newline. If it
-encounters a `?' or `\', it calls `skip_escaped_newlines' to skip over
-any potential escaped newlines before checking whether the number has
-been finished.
-
- Similarly code in the main body of `_cpp_lex_direct' cannot simply
-check for a `=' after a `+' character to determine whether it has a
-`+=' token; it needs to be prepared for an escaped newline of some
-sort. Such cases use the function `get_effective_char', which returns
-the first character after any intervening escaped newlines.
-
- The lexer needs to keep track of the correct column position,
-including counting tabs as specified by the `-ftabstop=' option. This
-should be done even within C-style comments; they can appear in the
-middle of a line, and we want to report diagnostics in the correct
-position for text appearing after the end of the comment.
-
- Some identifiers, such as `__VA_ARGS__' and poisoned identifiers,
-may be invalid and require a diagnostic. However, if they appear in a
-macro expansion we don't want to complain with each use of the macro.
-It is therefore best to catch them during the lexing stage, in
-`parse_identifier'. In both cases, whether a diagnostic is needed or
-not is dependent upon the lexer's state. For example, we don't want to
-issue a diagnostic for re-poisoning a poisoned identifier, or for using
-`__VA_ARGS__' in the expansion of a variable-argument macro. Therefore
-`parse_identifier' makes use of state flags to determine whether a
-diagnostic is appropriate. Since we change state on a per-token basis,
-and don't lex whole lines at a time, this is not a problem.
-
- Another place where state flags are used to change behavior is whilst
-lexing header names. Normally, a `<' would be lexed as a single token.
-After a `#include' directive, though, it should be lexed as a single
-token as far as the nearest `>' character. Note that we don't allow
-the terminators of header names to be escaped; the first `"' or `>'
-terminates the header name.
-
- Interpretation of some character sequences depends upon whether we
-are lexing C, C++ or Objective-C, and on the revision of the standard in
-force. For example, `::' is a single token in C++, but in C it is two
-separate `:' tokens and almost certainly a syntax error. Such cases
-are handled by `_cpp_lex_direct' based upon command-line flags stored
-in the `cpp_options' structure.
-
- Once a token has been lexed, it leads an independent existence. The
-spelling of numbers, identifiers and strings is copied to permanent
-storage from the original input buffer, so a token remains valid and
-correct even if its source buffer is freed with `_cpp_pop_buffer'. The
-storage holding the spellings of such tokens remains until the client
-program calls cpp_destroy, probably at the end of the translation unit.
-
-Lexing a line
-=============
-
- When the preprocessor was changed to return pointers to tokens, one
-feature I wanted was some sort of guarantee regarding how long a
-returned pointer remains valid. This is important to the stand-alone
-preprocessor, the future direction of the C family front ends, and even
-to cpplib itself internally.
-
- Occasionally the preprocessor wants to be able to peek ahead in the
-token stream. For example, after the name of a function-like macro, it
-wants to check the next token to see if it is an opening parenthesis.
-Another example is that, after reading the first few tokens of a
-`#pragma' directive and not recognizing it as a registered pragma, it
-wants to backtrack and allow the user-defined handler for unknown
-pragmas to access the full `#pragma' token stream. The stand-alone
-preprocessor wants to be able to test the current token with the
-previous one to see if a space needs to be inserted to preserve their
-separate tokenization upon re-lexing (paste avoidance), so it needs to
-be sure the pointer to the previous token is still valid. The
-recursive-descent C++ parser wants to be able to perform tentative
-parsing arbitrarily far ahead in the token stream, and then to be able
-to jump back to a prior position in that stream if necessary.
-
- The rule I chose, which is fairly natural, is to arrange that the
-preprocessor lex all tokens on a line consecutively into a token buffer,
-which I call a "token run", and when meeting an unescaped new line
-(newlines within comments do not count either), to start lexing back at
-the beginning of the run. Note that we do _not_ lex a line of tokens
-at once; if we did that `parse_identifier' would not have state flags
-available to warn about invalid identifiers (*note Invalid
-identifiers::).
-
- In other words, accessing tokens that appeared earlier in the current
-line is valid, but since each logical line overwrites the tokens of the
-previous line, tokens from prior lines are unavailable. In particular,
-since a directive only occupies a single logical line, this means that
-the directive handlers like the `#pragma' handler can jump around in
-the directive's tokens if necessary.
-
- Two issues remain: what about tokens that arise from macro
-expansions, and what happens when we have a long line that overflows
-the token run?
-
- Since we promise clients that we preserve the validity of pointers
-that we have already returned for tokens that appeared earlier in the
-line, we cannot reallocate the run. Instead, on overflow it is
-expanded by chaining a new token run on to the end of the existing one.
-
- The tokens forming a macro's replacement list are collected by the
-`#define' handler, and placed in storage that is only freed by
-`cpp_destroy'. So if a macro is expanded in our line of tokens, the
-pointers to the tokens of its expansion that we return will always
-remain valid. However, macros are a little trickier than that, since
-they give rise to three sources of fresh tokens. They are the built-in
-macros like `__LINE__', and the `#' and `##' operators for
-stringification and token pasting. I handled this by allocating space
-for these tokens from the lexer's token run chain. This means they
-automatically receive the same lifetime guarantees as lexed tokens, and
-we don't need to concern ourselves with freeing them.
-
- Lexing into a line of tokens solves some of the token memory
-management issues, but not all. The opening parenthesis after a
-function-like macro name might lie on a different line, and the front
-ends definitely want the ability to look ahead past the end of the
-current line. So cpplib only moves back to the start of the token run
-at the end of a line if the variable `keep_tokens' is zero.
-Line-buffering is quite natural for the preprocessor, and as a result
-the only time cpplib needs to increment this variable is whilst looking
-for the opening parenthesis to, and reading the arguments of, a
-function-like macro. In the near future cpplib will export an
-interface to increment and decrement this variable, so that clients can
-share full control over the lifetime of token pointers too.
-
- The routine `_cpp_lex_token' handles moving to new token runs,
-calling `_cpp_lex_direct' to lex new tokens, or returning
-previously-lexed tokens if we stepped back in the token stream. It also
-checks each token for the `BOL' flag, which might indicate a directive
-that needs to be handled, or require a start-of-line call-back to be
-made. `_cpp_lex_token' also handles skipping over tokens in failed
-conditional blocks, and invalidates the control macro of the
-multiple-include optimization if a token was successfully lexed outside
-a directive. In other words, its callers do not need to concern
-themselves with such issues.
-
-\1f
-File: cppinternals.info, Node: Hash Nodes, Next: Macro Expansion, Prev: Lexer, Up: Top
-
-Hash Nodes
-**********
-
- When cpplib encounters an "identifier", it generates a hash code for
-it and stores it in the hash table. By "identifier" we mean tokens
-with type `CPP_NAME'; this includes identifiers in the usual C sense,
-as well as keywords, directive names, macro names and so on. For
-example, all of `pragma', `int', `foo' and `__GNUC__' are identifiers
-and hashed when lexed.
-
- Each node in the hash table contain various information about the
-identifier it represents. For example, its length and type. At any one
-time, each identifier falls into exactly one of three categories:
-
- * Macros
-
- These have been declared to be macros, either on the command line
- or with `#define'. A few, such as `__TIME__' are built-ins
- entered in the hash table during initialization. The hash node
- for a normal macro points to a structure with more information
- about the macro, such as whether it is function-like, how many
- arguments it takes, and its expansion. Built-in macros are
- flagged as special, and instead contain an enum indicating which
- of the various built-in macros it is.
-
- * Assertions
-
- Assertions are in a separate namespace to macros. To enforce
- this, cpp actually prepends a `#' character before hashing and
- entering it in the hash table. An assertion's node points to a
- chain of answers to that assertion.
-
- * Void
-
- Everything else falls into this category--an identifier that is not
- currently a macro, or a macro that has since been undefined with
- `#undef'.
-
- When preprocessing C++, this category also includes the named
- operators, such as `xor'. In expressions these behave like the
- operators they represent, but in contexts where the spelling of a
- token matters they are spelt differently. This spelling
- distinction is relevant when they are operands of the stringizing
- and pasting macro operators `#' and `##'. Named operator hash
- nodes are flagged, both to catch the spelling distinction and to
- prevent them from being defined as macros.
-
- The same identifiers share the same hash node. Since each identifier
-token, after lexing, contains a pointer to its hash node, this is used
-to provide rapid lookup of various information. For example, when
-parsing a `#define' statement, CPP flags each argument's identifier
-hash node with the index of that argument. This makes duplicated
-argument checking an O(1) operation for each argument. Similarly, for
-each identifier in the macro's expansion, lookup to see if it is an
-argument, and which argument it is, is also an O(1) operation. Further,
-each directive name, such as `endif', has an associated directive enum
-stored in its hash node, so that directive lookup is also O(1).
-
-\1f
-File: cppinternals.info, Node: Macro Expansion, Next: Token Spacing, Prev: Hash Nodes, Up: Top
-
-Macro Expansion Algorithm
-*************************
-
- Macro expansion is a tricky operation, fraught with nasty corner
-cases and situations that render what you thought was a nifty way to
-optimize the preprocessor's expansion algorithm wrong in quite subtle
-ways.
-
- I strongly recommend you have a good grasp of how the C and C++
-standards require macros to be expanded before diving into this
-section, let alone the code!. If you don't have a clear mental picture
-of how things like nested macro expansion, stringification and token
-pasting are supposed to work, damage to your sanity can quickly result.
-
-Internal representation of macros
-=================================
-
- The preprocessor stores macro expansions in tokenized form. This
-saves repeated lexing passes during expansion, at the cost of a small
-increase in memory consumption on average. The tokens are stored
-contiguously in memory, so a pointer to the first one and a token count
-is all you need to get the replacement list of a macro.
-
- If the macro is a function-like macro the preprocessor also stores
-its parameters, in the form of an ordered list of pointers to the hash
-table entry of each parameter's identifier. Further, in the macro's
-stored expansion each occurrence of a parameter is replaced with a
-special token of type `CPP_MACRO_ARG'. Each such token holds the index
-of the parameter it represents in the parameter list, which allows
-rapid replacement of parameters with their arguments during expansion.
-Despite this optimization it is still necessary to store the original
-parameters to the macro, both for dumping with e.g., `-dD', and to warn
-about non-trivial macro redefinitions when the parameter names have
-changed.
-
-Macro expansion overview
-========================
-
- The preprocessor maintains a "context stack", implemented as a
-linked list of `cpp_context' structures, which together represent the
-macro expansion state at any one time. The `struct cpp_reader' member
-variable `context' points to the current top of this stack. The top
-normally holds the unexpanded replacement list of the innermost macro
-under expansion, except when cpplib is about to pre-expand an argument,
-in which case it holds that argument's unexpanded tokens.
-
- When there are no macros under expansion, cpplib is in "base
-context". All contexts other than the base context contain a
-contiguous list of tokens delimited by a starting and ending token.
-When not in base context, cpplib obtains the next token from the list
-of the top context. If there are no tokens left in the list, it pops
-that context off the stack, and subsequent ones if necessary, until an
-unexhausted context is found or it returns to base context. In base
-context, cpplib reads tokens directly from the lexer.
-
- If it encounters an identifier that is both a macro and enabled for
-expansion, cpplib prepares to push a new context for that macro on the
-stack by calling the routine `enter_macro_context'. When this routine
-returns, the new context will contain the unexpanded tokens of the
-replacement list of that macro. In the case of function-like macros,
-`enter_macro_context' also replaces any parameters in the replacement
-list, stored as `CPP_MACRO_ARG' tokens, with the appropriate macro
-argument. If the standard requires that the parameter be replaced with
-its expanded argument, the argument will have been fully macro expanded
-first.
-
- `enter_macro_context' also handles special macros like `__LINE__'.
-Although these macros expand to a single token which cannot contain any
-further macros, for reasons of token spacing (*note Token Spacing::)
-and simplicity of implementation, cpplib handles these special macros
-by pushing a context containing just that one token.
-
- The final thing that `enter_macro_context' does before returning is
-to mark the macro disabled for expansion (except for special macros
-like `__TIME__'). The macro is re-enabled when its context is later
-popped from the context stack, as described above. This strict
-ordering ensures that a macro is disabled whilst its expansion is being
-scanned, but that it is _not_ disabled whilst any arguments to it are
-being expanded.
-
-Scanning the replacement list for macros to expand
-==================================================
-
- The C standard states that, after any parameters have been replaced
-with their possibly-expanded arguments, the replacement list is scanned
-for nested macros. Further, any identifiers in the replacement list
-that are not expanded during this scan are never again eligible for
-expansion in the future, if the reason they were not expanded is that
-the macro in question was disabled.
-
- Clearly this latter condition can only apply to tokens resulting from
-argument pre-expansion. Other tokens never have an opportunity to be
-re-tested for expansion. It is possible for identifiers that are
-function-like macros to not expand initially but to expand during a
-later scan. This occurs when the identifier is the last token of an
-argument (and therefore originally followed by a comma or a closing
-parenthesis in its macro's argument list), and when it replaces its
-parameter in the macro's replacement list, the subsequent token happens
-to be an opening parenthesis (itself possibly the first token of an
-argument).
-
- It is important to note that when cpplib reads the last token of a
-given context, that context still remains on the stack. Only when
-looking for the _next_ token do we pop it off the stack and drop to a
-lower context. This makes backing up by one token easy, but more
-importantly ensures that the macro corresponding to the current context
-is still disabled when we are considering the last token of its
-replacement list for expansion (or indeed expanding it). As an
-example, which illustrates many of the points above, consider
-
- #define foo(x) bar x
- foo(foo) (2)
-
-which fully expands to `bar foo (2)'. During pre-expansion of the
-argument, `foo' does not expand even though the macro is enabled, since
-it has no following parenthesis [pre-expansion of an argument only uses
-tokens from that argument; it cannot take tokens from whatever follows
-the macro invocation]. This still leaves the argument token `foo'
-eligible for future expansion. Then, when re-scanning after argument
-replacement, the token `foo' is rejected for expansion, and marked
-ineligible for future expansion, since the macro is now disabled. It
-is disabled because the replacement list `bar foo' of the macro is
-still on the context stack.
-
- If instead the algorithm looked for an opening parenthesis first and
-then tested whether the macro were disabled it would be subtly wrong.
-In the example above, the replacement list of `foo' would be popped in
-the process of finding the parenthesis, re-enabling `foo' and expanding
-it a second time.
-
-Looking for a function-like macro's opening parenthesis
-=======================================================
-
- Function-like macros only expand when immediately followed by a
-parenthesis. To do this cpplib needs to temporarily disable macros and
-read the next token. Unfortunately, because of spacing issues (*note
-Token Spacing::), there can be fake padding tokens in-between, and if
-the next real token is not a parenthesis cpplib needs to be able to
-back up that one token as well as retain the information in any
-intervening padding tokens.
-
- Backing up more than one token when macros are involved is not
-permitted by cpplib, because in general it might involve issues like
-restoring popped contexts onto the context stack, which are too hard.
-Instead, searching for the parenthesis is handled by a special
-function, `funlike_invocation_p', which remembers padding information
-as it reads tokens. If the next real token is not an opening
-parenthesis, it backs up that one token, and then pushes an extra
-context just containing the padding information if necessary.
-
-Marking tokens ineligible for future expansion
-==============================================
-
- As discussed above, cpplib needs a way of marking tokens as
-unexpandable. Since the tokens cpplib handles are read-only once they
-have been lexed, it instead makes a copy of the token and adds the flag
-`NO_EXPAND' to the copy.
-
- For efficiency and to simplify memory management by avoiding having
-to remember to free these tokens, they are allocated as temporary tokens
-from the lexer's current token run (*note Lexing a line::) using the
-function `_cpp_temp_token'. The tokens are then re-used once the
-current line of tokens has been read in.
-
- This might sound unsafe. However, tokens runs are not re-used at the
-end of a line if it happens to be in the middle of a macro argument
-list, and cpplib only wants to back-up more than one lexer token in
-situations where no macro expansion is involved, so the optimization is
-safe.
-
-\1f
-File: cppinternals.info, Node: Token Spacing, Next: Line Numbering, Prev: Macro Expansion, Up: Top
-
-Token Spacing
-*************
-
- First, let's look at an issue that only concerns the stand-alone
-preprocessor: we want to guarantee that re-reading its preprocessed
-output results in an identical token stream. Without taking special
-measures, this might not be the case because of macro substitution.
-For example:
-
- #define PLUS +
- #define EMPTY
- #define f(x) =x=
- +PLUS -EMPTY- PLUS+ f(=)
- ==> + + - - + + = = =
- _not_
- ==> ++ -- ++ ===
-
- One solution would be to simply insert a space between all adjacent
-tokens. However, we would like to keep space insertion to a minimum,
-both for aesthetic reasons and because it causes problems for people who
-still try to abuse the preprocessor for things like Fortran source and
-Makefiles.
-
- For now, just notice that when tokens are added (or removed, as
-shown by the `EMPTY' example) from the original lexed token stream, we
-need to check for accidental token pasting. We call this "paste
-avoidance". Token addition and removal can only occur because of macro
-expansion, but accidental pasting can occur in many places: both before
-and after each macro replacement, each argument replacement, and
-additionally each token created by the `#' and `##' operators.
-
- Let's look at how the preprocessor gets whitespace output correct
-normally. The `cpp_token' structure contains a flags byte, and one of
-those flags is `PREV_WHITE'. This is flagged by the lexer, and
-indicates that the token was preceded by whitespace of some form other
-than a new line. The stand-alone preprocessor can use this flag to
-decide whether to insert a space between tokens in the output.
-
- Now consider the result of the following macro expansion:
-
- #define add(x, y, z) x + y +z;
- sum = add (1,2, 3);
- ==> sum = 1 + 2 +3;
-
- The interesting thing here is that the tokens `1' and `2' are output
-with a preceding space, and `3' is output without a preceding space,
-but when lexed none of these tokens had that property. Careful
-consideration reveals that `1' gets its preceding whitespace from the
-space preceding `add' in the macro invocation, _not_ replacement list.
-`2' gets its whitespace from the space preceding the parameter `y' in
-the macro replacement list, and `3' has no preceding space because
-parameter `z' has none in the replacement list.
-
- Once lexed, tokens are effectively fixed and cannot be altered, since
-pointers to them might be held in many places, in particular by
-in-progress macro expansions. So instead of modifying the two tokens
-above, the preprocessor inserts a special token, which I call a
-"padding token", into the token stream to indicate that spacing of the
-subsequent token is special. The preprocessor inserts padding tokens
-in front of every macro expansion and expanded macro argument. These
-point to a "source token" from which the subsequent real token should
-inherit its spacing. In the above example, the source tokens are `add'
-in the macro invocation, and `y' and `z' in the macro replacement list,
-respectively.
-
- It is quite easy to get multiple padding tokens in a row, for
-example if a macro's first replacement token expands straight into
-another macro.
-
- #define foo bar
- #define bar baz
- [foo]
- ==> [baz]
-
- Here, two padding tokens are generated with sources the `foo' token
-between the brackets, and the `bar' token from foo's replacement list,
-respectively. Clearly the first padding token is the one we should
-use, so our output code should contain a rule that the first padding
-token in a sequence is the one that matters.
-
- But what if we happen to leave a macro expansion? Adjusting the
-above example slightly:
-
- #define foo bar
- #define bar EMPTY baz
- #define EMPTY
- [foo] EMPTY;
- ==> [ baz] ;
-
- As shown, now there should be a space before `baz' and the semicolon
-in the output.
-
- The rules we decided above fail for `baz': we generate three padding
-tokens, one per macro invocation, before the token `baz'. We would
-then have it take its spacing from the first of these, which carries
-source token `foo' with no leading space.
-
- It is vital that cpplib get spacing correct in these examples since
-any of these macro expansions could be stringified, where spacing
-matters.
-
- So, this demonstrates that not just entering macro and argument
-expansions, but leaving them requires special handling too. I made
-cpplib insert a padding token with a `NULL' source token when leaving
-macro expansions, as well as after each replaced argument in a macro's
-replacement list. It also inserts appropriate padding tokens on either
-side of tokens created by the `#' and `##' operators. I expanded the
-rule so that, if we see a padding token with a `NULL' source token,
-_and_ that source token has no leading space, then we behave as if we
-have seen no padding tokens at all. A quick check shows this rule will
-then get the above example correct as well.
-
- Now a relationship with paste avoidance is apparent: we have to be
-careful about paste avoidance in exactly the same locations we have
-padding tokens in order to get white space correct. This makes
-implementation of paste avoidance easy: wherever the stand-alone
-preprocessor is fixing up spacing because of padding tokens, and it
-turns out that no space is needed, it has to take the extra step to
-check that a space is not needed after all to avoid an accidental paste.
-The function `cpp_avoid_paste' advises whether a space is required
-between two consecutive tokens. To avoid excessive spacing, it tries
-hard to only require a space if one is likely to be necessary, but for
-reasons of efficiency it is slightly conservative and might recommend a
-space where one is not strictly needed.
-
-\1f
-File: cppinternals.info, Node: Line Numbering, Next: Guard Macros, Prev: Token Spacing, Up: Top
-
-Line numbering
-**************
-
-Just which line number anyway?
-==============================
-
- There are three reasonable requirements a cpplib client might have
-for the line number of a token passed to it:
-
- * The source line it was lexed on.
-
- * The line it is output on. This can be different to the line it was
- lexed on if, for example, there are intervening escaped newlines or
- C-style comments. For example:
-
- foo /* A long
- comment */ bar \
- baz
- =>
- foo bar baz
-
- * If the token results from a macro expansion, the line of the macro
- name, or possibly the line of the closing parenthesis in the case
- of function-like macro expansion.
-
- The `cpp_token' structure contains `line' and `col' members. The
-lexer fills these in with the line and column of the first character of
-the token. Consequently, but maybe unexpectedly, a token from the
-replacement list of a macro expansion carries the location of the token
-within the `#define' directive, because cpplib expands a macro by
-returning pointers to the tokens in its replacement list. The current
-implementation of cpplib assigns tokens created from built-in macros
-and the `#' and `##' operators the location of the most recently lexed
-token. This is a because they are allocated from the lexer's token
-runs, and because of the way the diagnostic routines infer the
-appropriate location to report.
-
- The diagnostic routines in cpplib display the location of the most
-recently _lexed_ token, unless they are passed a specific line and
-column to report. For diagnostics regarding tokens that arise from
-macro expansions, it might also be helpful for the user to see the
-original location in the macro definition that the token came from.
-Since that is exactly the information each token carries, such an
-enhancement could be made relatively easily in future.
-
- The stand-alone preprocessor faces a similar problem when determining
-the correct line to output the token on: the position attached to a
-token is fairly useless if the token came from a macro expansion. All
-tokens on a logical line should be output on its first physical line, so
-the token's reported location is also wrong if it is part of a physical
-line other than the first.
-
- To solve these issues, cpplib provides a callback that is generated
-whenever it lexes a preprocessing token that starts a new logical line
-other than a directive. It passes this token (which may be a `CPP_EOF'
-token indicating the end of the translation unit) to the callback
-routine, which can then use the line and column of this token to
-produce correct output.
-
-Representation of line numbers
-==============================
-
- As mentioned above, cpplib stores with each token the line number
-that it was lexed on. In fact, this number is not the number of the
-line in the source file, but instead bears more resemblance to the
-number of the line in the translation unit.
-
- The preprocessor maintains a monotonic increasing line count, which
-is incremented at every new line character (and also at the end of any
-buffer that does not end in a new line). Since a line number of zero is
-useful to indicate certain special states and conditions, this variable
-starts counting from one.
-
- This variable therefore uniquely enumerates each line in the
-translation unit. With some simple infrastructure, it is straight
-forward to map from this to the original source file and line number
-pair, saving space whenever line number information needs to be saved.
-The code the implements this mapping lies in the files `line-map.c' and
-`line-map.h'.
-
- Command-line macros and assertions are implemented by pushing a
-buffer containing the right hand side of an equivalent `#define' or
-`#assert' directive. Some built-in macros are handled similarly.
-Since these are all processed before the first line of the main input
-file, it will typically have an assigned line closer to twenty than to
-one.
-
-\1f
-File: cppinternals.info, Node: Guard Macros, Next: Files, Prev: Line Numbering, Up: Top
-
-The Multiple-Include Optimization
-*********************************
-
- Header files are often of the form
-
- #ifndef FOO
- #define FOO
- ...
- #endif
-
-to prevent the compiler from processing them more than once. The
-preprocessor notices such header files, so that if the header file
-appears in a subsequent `#include' directive and `FOO' is defined, then
-it is ignored and it doesn't preprocess or even re-open the file a
-second time. This is referred to as the "multiple include
-optimization".
-
- Under what circumstances is such an optimization valid? If the file
-were included a second time, it can only be optimized away if that
-inclusion would result in no tokens to return, and no relevant
-directives to process. Therefore the current implementation imposes
-requirements and makes some allowances as follows:
-
- 1. There must be no tokens outside the controlling `#if'-`#endif'
- pair, but whitespace and comments are permitted.
-
- 2. There must be no directives outside the controlling directive
- pair, but the "null directive" (a line containing nothing other
- than a single `#' and possibly whitespace) is permitted.
-
- 3. The opening directive must be of the form
-
- #ifndef FOO
-
- or
-
- #if !defined FOO [equivalently, #if !defined(FOO)]
-
- 4. In the second form above, the tokens forming the `#if' expression
- must have come directly from the source file--no macro expansion
- must have been involved. This is because macro definitions can
- change, and tracking whether or not a relevant change has been
- made is not worth the implementation cost.
-
- 5. There can be no `#else' or `#elif' directives at the outer
- conditional block level, because they would probably contain
- something of interest to a subsequent pass.
-
- First, when pushing a new file on the buffer stack,
-`_stack_include_file' sets the controlling macro `mi_cmacro' to `NULL',
-and sets `mi_valid' to `true'. This indicates that the preprocessor
-has not yet encountered anything that would invalidate the
-multiple-include optimization. As described in the next few
-paragraphs, these two variables having these values effectively
-indicates top-of-file.
-
- When about to return a token that is not part of a directive,
-`_cpp_lex_token' sets `mi_valid' to `false'. This enforces the
-constraint that tokens outside the controlling conditional block
-invalidate the optimization.
-
- The `do_if', when appropriate, and `do_ifndef' directive handlers
-pass the controlling macro to the function `push_conditional'. cpplib
-maintains a stack of nested conditional blocks, and after processing
-every opening conditional this function pushes an `if_stack' structure
-onto the stack. In this structure it records the controlling macro for
-the block, provided there is one and we're at top-of-file (as described
-above). If an `#elif' or `#else' directive is encountered, the
-controlling macro for that block is cleared to `NULL'. Otherwise, it
-survives until the `#endif' closing the block, upon which `do_endif'
-sets `mi_valid' to true and stores the controlling macro in `mi_cmacro'.
-
- `_cpp_handle_directive' clears `mi_valid' when processing any
-directive other than an opening conditional and the null directive.
-With this, and requiring top-of-file to record a controlling macro, and
-no `#else' or `#elif' for it to survive and be copied to `mi_cmacro' by
-`do_endif', we have enforced the absence of directives outside the main
-conditional block for the optimization to be on.
-
- Note that whilst we are inside the conditional block, `mi_valid' is
-likely to be reset to `false', but this does not matter since the the
-closing `#endif' restores it to `true' if appropriate.
-
- Finally, since `_cpp_lex_direct' pops the file off the buffer stack
-at `EOF' without returning a token, if the `#endif' directive was not
-followed by any tokens, `mi_valid' is `true' and `_cpp_pop_file_buffer'
-remembers the controlling macro associated with the file. Subsequent
-calls to `stack_include_file' result in no buffer being pushed if the
-controlling macro is defined, effecting the optimization.
-
- A quick word on how we handle the
-
- #if !defined FOO
-
-case. `_cpp_parse_expr' and `parse_defined' take steps to see whether
-the three stages `!', `defined-expression' and `end-of-directive' occur
-in order in a `#if' expression. If so, they return the guard macro to
-`do_if' in the variable `mi_ind_cmacro', and otherwise set it to `NULL'.
-`enter_macro_context' sets `mi_valid' to false, so if a macro was
-expanded whilst parsing any part of the expression, then the
-top-of-file test in `push_conditional' fails and the optimization is
-turned off.
-
-\1f
-File: cppinternals.info, Node: Files, Next: Index, Prev: Guard Macros, Up: Top
-
-File Handling
-*************
-
- Fairly obviously, the file handling code of cpplib resides in the
-file `cppfiles.c'. It takes care of the details of file searching,
-opening, reading and caching, for both the main source file and all the
-headers it recursively includes.
-
- The basic strategy is to minimize the number of system calls. On
-many systems, the basic `open ()' and `fstat ()' system calls can be
-quite expensive. For every `#include'-d file, we need to try all the
-directories in the search path until we find a match. Some projects,
-such as glibc, pass twenty or thirty include paths on the command line,
-so this can rapidly become time consuming.
-
- For a header file we have not encountered before we have little
-choice but to do this. However, it is often the case that the same
-headers are repeatedly included, and in these cases we try to avoid
-repeating the filesystem queries whilst searching for the correct file.
-
- For each file we try to open, we store the constructed path in a
-splay tree. This path first undergoes simplification by the function
-`_cpp_simplify_pathname'. For example, `/usr/include/bits/../foo.h' is
-simplified to `/usr/include/foo.h' before we enter it in the splay tree
-and try to `open ()' the file. CPP will then find subsequent uses of
-`foo.h', even as `/usr/include/foo.h', in the splay tree and save
-system calls.
-
- Further, it is likely the file contents have also been cached,
-saving a `read ()' system call. We don't bother caching the contents of
-header files that are re-inclusion protected, and whose re-inclusion
-macro is defined when we leave the header file for the first time. If
-the host supports it, we try to map suitably large files into memory,
-rather than reading them in directly.
-
- The include paths are internally stored on a null-terminated
-singly-linked list, starting with the `"header.h"' directory search
-chain, which then links into the `<header.h>' directory chain.
-
- Files included with the `<foo.h>' syntax start the lookup directly
-in the second half of this chain. However, files included with the
-`"foo.h"' syntax start at the beginning of the chain, but with one
-extra directory prepended. This is the directory of the current file;
-the one containing the `#include' directive. Prepending this directory
-on a per-file basis is handled by the function `search_from'.
-
- Note that a header included with a directory component, such as
-`#include "mydir/foo.h"' and opened as
-`/usr/local/include/mydir/foo.h', will have the complete path minus the
-basename `foo.h' as the current directory.
-
- Enough information is stored in the splay tree that CPP can
-immediately tell whether it can skip the header file because of the
-multiple include optimization, whether the file didn't exist or
-couldn't be opened for some reason, or whether the header was flagged
-not to be re-used, as it is with the obsolete `#import' directive.
-
- For the benefit of MS-DOS filesystems with an 8.3 filename
-limitation, CPP offers the ability to treat various include file names
-as aliases for the real header files with shorter names. The map from
-one to the other is found in a special file called `header.gcc', stored
-in the command line (or system) include directories to which the mapping
-applies. This may be higher up the directory tree than the full path to
-the file minus the base name.
-
-\1f
-File: cppinternals.info, Node: Index, Prev: Files, Up: Top
-
-Index
-*****
-
-* Menu:
-
-* assertions: Hash Nodes.
-* controlling macros: Guard Macros.
-* escaped newlines: Lexer.
-* files: Files.
-* guard macros: Guard Macros.
-* hash table: Hash Nodes.
-* header files: Conventions.
-* identifiers: Hash Nodes.
-* interface: Conventions.
-* lexer: Lexer.
-* line numbers: Line Numbering.
-* macro expansion: Macro Expansion.
-* macro representation (internal): Macro Expansion.
-* macros: Hash Nodes.
-* multiple-include optimization: Guard Macros.
-* named operators: Hash Nodes.
-* newlines: Lexer.
-* paste avoidance: Token Spacing.
-* spacing: Token Spacing.
-* token run: Lexer.
-* token spacing: Token Spacing.
-
-
-\1f
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-End Tag Table
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
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-Node: Type encoding\7f713871
-Node: Garbage Collection\7f717123
-Node: Constant string objects\7f719787
-Node: compatibility_alias\7f721421
-Node: Compatibility\7f722300
-Node: Gcov\7f728887
-Node: Gcov Intro\7f729356
-Node: Invoking Gcov\7f732031
-Node: Gcov and Optimization\7f738105
-Node: Gcov Data Files\7f739522
-Node: Trouble\7f743087
-Node: Actual Bugs\7f744681
-Node: Cross-Compiler Problems\7f745589
-Node: Interoperation\7f747099
-Node: External Bugs\7f759807
-Node: Incompatibilities\7f761299
-Node: Fixed Headers\7f770907
-Node: Standard Libraries\7f773216
-Node: Disappointments\7f774586
-Node: C++ Misunderstandings\7f779308
-Node: Static Definitions\7f780034
-Node: Temporaries\7f781081
-Node: Copy Assignment\7f783058
-Node: Protoize Caveats\7f784876
-Node: Non-bugs\7f788831
-Node: Warnings and Errors\7f798723
-Node: Bugs\7f800483
-Node: Bug Criteria\7f801836
-Node: Bug Lists\7f804260
-Node: Bug Reporting\7f804819
-Node: gccbug\7f816922
-Node: Service\7f817742
-Node: Contributing\7f818488
-Node: VMS\7f819227
-Node: Include Files and VMS\7f819609
-Node: Global Declarations\7f823474
-Node: VMS Misc\7f827778
-Node: Funding\7f832081
-Node: GNU Project\7f834576
-Node: Copying\7f835227
-Node: GNU Free Documentation License\7f854438
-Node: Contributors\7f874322
-Node: Option Index\7f899250
-Node: Index\7f969159
-\1f
-End Tag Table
-This is doc/gcc.info, produced by makeinfo version 4.5 from
+This is doc/gcc.info, produced by makeinfo version 4.11 from
doc/gcc.texi.
INFO-DIR-SECTION Programming
Introduction
************
- This manual documents how to use the GNU compilers, as well as their
+This manual documents how to use the GNU compilers, as well as their
features and incompatibilities, and how to report bugs. It corresponds
to GCC version 3.2.3. The internals of the GNU compilers, including
how to port them to new targets and some information about how to write
\1f
File: gcc.info, Node: G++ and GCC, Next: Standards, Prev: Top, Up: Top
-Compile C, C++, Objective-C, Ada, Fortran, or Java
-**************************************************
+1 Compile C, C++, Objective-C, Ada, Fortran, or Java
+****************************************************
- Several versions of the compiler (C, C++, Objective-C, Ada, Fortran,
+Several versions of the compiler (C, C++, Objective-C, Ada, Fortran,
and Java) are integrated; this is why we use the name "GNU Compiler
Collection". GCC can compile programs written in any of these
languages. The Ada, Fortran, and Java compilers are described in
\1f
File: gcc.info, Node: Standards, Next: Invoking GCC, Prev: G++ and GCC, Up: Top
-Language Standards Supported by GCC
-***********************************
+2 Language Standards Supported by GCC
+*************************************
- For each language compiled by GCC for which there is a standard, GCC
+For each language compiled by GCC for which there is a standard, GCC
attempts to follow one or more versions of that standard, possibly with
some exceptions, and possibly with some extensions.
\1f
File: gcc.info, Node: Invoking GCC, Next: C Implementation, Prev: Standards, Up: Top
-GCC Command Options
-*******************
+3 GCC Command Options
+*********************
- When you invoke GCC, it normally does preprocessing, compilation,
+When you invoke GCC, it normally does preprocessing, compilation,
assembly and linking. The "overall options" allow you to stop this
process at an intermediate stage. For example, the `-c' option says
not to run the linker. Then the output consists of object files output
\1f
File: gcc.info, Node: Option Summary, Next: Overall Options, Up: Invoking GCC
-Option Summary
-==============
+3.1 Option Summary
+==================
- Here is a summary of all the options, grouped by type. Explanations
-are in the following sections.
+Here is a summary of all the options, grouped by type. Explanations are
+in the following sections.
_Overall Options_
*Note Options Controlling the Kind of Output: Overall Options.
- -c -S -E -o FILE -pipe -pass-exit-codes -x LANGUAGE
+ -c -S -E -o FILE -pipe -pass-exit-codes -x LANGUAGE
-v -### --help --target-help --version
_C Language Options_
*Note Options Controlling C Dialect: C Dialect Options.
- -ansi -std=STANDARD -aux-info FILENAME
- -fno-asm -fno-builtin -fno-builtin-FUNCTION
- -fhosted -ffreestanding
- -trigraphs -no-integrated-cpp -traditional -traditional-cpp
- -fallow-single-precision -fcond-mismatch
- -fsigned-bitfields -fsigned-char
- -funsigned-bitfields -funsigned-char
+ -ansi -std=STANDARD -aux-info FILENAME
+ -fno-asm -fno-builtin -fno-builtin-FUNCTION
+ -fhosted -ffreestanding
+ -trigraphs -no-integrated-cpp -traditional -traditional-cpp
+ -fallow-single-precision -fcond-mismatch
+ -fsigned-bitfields -fsigned-char
+ -funsigned-bitfields -funsigned-char
-fwritable-strings
_C++ Language Options_
*Note Options Controlling C++ Dialect: C++ Dialect Options.
- -fno-access-control -fcheck-new -fconserve-space
- -fno-const-strings -fdollars-in-identifiers
- -fno-elide-constructors
- -fno-enforce-eh-specs -fexternal-templates
- -falt-external-templates
- -ffor-scope -fno-for-scope -fno-gnu-keywords
- -fno-implicit-templates
- -fno-implicit-inline-templates
- -fno-implement-inlines -fms-extensions
- -fno-nonansi-builtins -fno-operator-names
- -fno-optional-diags -fpermissive
- -frepo -fno-rtti -fstats -ftemplate-depth-N
- -fuse-cxa-atexit -fvtable-gc -fno-weak -nostdinc++
- -fno-default-inline -Wabi -Wctor-dtor-privacy
- -Wnon-virtual-dtor -Wreorder
- -Weffc++ -Wno-deprecated
- -Wno-non-template-friend -Wold-style-cast
- -Woverloaded-virtual -Wno-pmf-conversions
+ -fno-access-control -fcheck-new -fconserve-space
+ -fno-const-strings -fdollars-in-identifiers
+ -fno-elide-constructors
+ -fno-enforce-eh-specs -fexternal-templates
+ -falt-external-templates
+ -ffor-scope -fno-for-scope -fno-gnu-keywords
+ -fno-implicit-templates
+ -fno-implicit-inline-templates
+ -fno-implement-inlines -fms-extensions
+ -fno-nonansi-builtins -fno-operator-names
+ -fno-optional-diags -fpermissive
+ -frepo -fno-rtti -fstats -ftemplate-depth-N
+ -fuse-cxa-atexit -fvtable-gc -fno-weak -nostdinc++
+ -fno-default-inline -Wabi -Wctor-dtor-privacy
+ -Wnon-virtual-dtor -Wreorder
+ -Weffc++ -Wno-deprecated
+ -Wno-non-template-friend -Wold-style-cast
+ -Woverloaded-virtual -Wno-pmf-conversions
-Wsign-promo -Wsynth
_Objective-C Language Options_
*Note Options Controlling Objective-C Dialect: Objective-C Dialect
Options.
- -fconstant-string-class=CLASS-NAME
- -fgnu-runtime -fnext-runtime -gen-decls
+ -fconstant-string-class=CLASS-NAME
+ -fgnu-runtime -fnext-runtime -gen-decls
-Wno-protocol -Wselector
_Language Independent Options_
*Note Options to Control Diagnostic Messages Formatting: Language
Independent Options.
- -fmessage-length=N
+ -fmessage-length=N
-fdiagnostics-show-location=[once|every-line]
_Warning Options_
*Note Options to Request or Suppress Warnings: Warning Options.
- -fsyntax-only -pedantic -pedantic-errors
- -w -W -Wall -Waggregate-return
- -Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment
- -Wconversion -Wno-deprecated-declarations
- -Wdisabled-optimization -Wdiv-by-zero -Werror
- -Wfloat-equal -Wformat -Wformat=2
- -Wformat-nonliteral -Wformat-security
- -Wimplicit -Wimplicit-int
- -Wimplicit-function-declaration
- -Werror-implicit-function-declaration
- -Wimport -Winline
- -Wlarger-than-LEN -Wlong-long
- -Wmain -Wmissing-braces
- -Wmissing-format-attribute -Wmissing-noreturn
- -Wmultichar -Wno-format-extra-args -Wno-format-y2k
- -Wno-import -Wpacked -Wpadded
- -Wparentheses -Wpointer-arith -Wredundant-decls
- -Wreturn-type -Wsequence-point -Wshadow
- -Wsign-compare -Wswitch -Wsystem-headers
- -Wtrigraphs -Wundef -Wuninitialized
- -Wunknown-pragmas -Wunreachable-code
- -Wunused -Wunused-function -Wunused-label -Wunused-parameter
+ -fsyntax-only -pedantic -pedantic-errors
+ -w -W -Wall -Waggregate-return
+ -Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment
+ -Wconversion -Wno-deprecated-declarations
+ -Wdisabled-optimization -Wdiv-by-zero -Werror
+ -Wfloat-equal -Wformat -Wformat=2
+ -Wformat-nonliteral -Wformat-security
+ -Wimplicit -Wimplicit-int
+ -Wimplicit-function-declaration
+ -Werror-implicit-function-declaration
+ -Wimport -Winline
+ -Wlarger-than-LEN -Wlong-long
+ -Wmain -Wmissing-braces
+ -Wmissing-format-attribute -Wmissing-noreturn
+ -Wmultichar -Wno-format-extra-args -Wno-format-y2k
+ -Wno-import -Wpacked -Wpadded
+ -Wparentheses -Wpointer-arith -Wredundant-decls
+ -Wreturn-type -Wsequence-point -Wshadow
+ -Wsign-compare -Wswitch -Wsystem-headers
+ -Wtrigraphs -Wundef -Wuninitialized
+ -Wunknown-pragmas -Wunreachable-code
+ -Wunused -Wunused-function -Wunused-label -Wunused-parameter
-Wunused-value -Wunused-variable -Wwrite-strings
_C-only Warning Options_
- -Wbad-function-cast -Wmissing-declarations
- -Wmissing-prototypes -Wnested-externs
+ -Wbad-function-cast -Wmissing-declarations
+ -Wmissing-prototypes -Wnested-externs
-Wstrict-prototypes -Wtraditional
_Debugging Options_
*Note Options for Debugging Your Program or GCC: Debugging Options.
- -dLETTERS -dumpspecs -dumpmachine -dumpversion
- -fdump-unnumbered -fdump-translation-unit[-N]
- -fdump-class-hierarchy[-N]
- -fdump-tree-original[-N] -fdump-tree-optimized[-N]
- -fdump-tree-inlined[-N]
- -fmem-report -fpretend-float
- -fprofile-arcs -fsched-verbose=N
- -ftest-coverage -ftime-report
- -g -gLEVEL -gcoff -gdwarf -gdwarf-1 -gdwarf-1+ -gdwarf-2
- -ggdb -gstabs -gstabs+ -gvms -gxcoff -gxcoff+
- -p -pg -print-file-name=LIBRARY -print-libgcc-file-name
- -print-multi-directory -print-multi-lib
- -print-prog-name=PROGRAM -print-search-dirs -Q
+ -dLETTERS -dumpspecs -dumpmachine -dumpversion
+ -fdump-unnumbered -fdump-translation-unit[-N]
+ -fdump-class-hierarchy[-N]
+ -fdump-tree-original[-N] -fdump-tree-optimized[-N]
+ -fdump-tree-inlined[-N]
+ -fmem-report -fpretend-float
+ -fprofile-arcs -fsched-verbose=N
+ -ftest-coverage -ftime-report
+ -g -gLEVEL -gcoff -gdwarf -gdwarf-1 -gdwarf-1+ -gdwarf-2
+ -ggdb -gstabs -gstabs+ -gvms -gxcoff -gxcoff+
+ -p -pg -print-file-name=LIBRARY -print-libgcc-file-name
+ -print-multi-directory -print-multi-lib
+ -print-prog-name=PROGRAM -print-search-dirs -Q
-save-temps -time
_Optimization Options_
*Note Options that Control Optimization: Optimize Options.
- -falign-functions=N -falign-jumps=N
- -falign-labels=N -falign-loops=N
- -fbounds-check
- -fbranch-probabilities -fcaller-saves -fcprop-registers
- -fcse-follow-jumps -fcse-skip-blocks -fdata-sections
- -fdelayed-branch -fdelete-null-pointer-checks
- -fexpensive-optimizations -ffast-math -ffloat-store
- -fforce-addr -fforce-mem -ffunction-sections
- -fgcse -fgcse-lm -fgcse-sm
- -finline-functions -finline-limit=N -fkeep-inline-functions
- -fkeep-static-consts -fmerge-constants -fmerge-all-constants
- -fmove-all-movables -fno-branch-count-reg
- -fno-default-inline -fno-defer-pop
- -fno-function-cse -fno-guess-branch-probability
- -fno-inline -fno-math-errno -fno-peephole -fno-peephole2
- -funsafe-math-optimizations -fno-trapping-math
- -fomit-frame-pointer -foptimize-register-move
- -foptimize-sibling-calls -fprefetch-loop-arrays
- -freduce-all-givs -fregmove -frename-registers
- -frerun-cse-after-loop -frerun-loop-opt
- -fschedule-insns -fschedule-insns2
- -fno-sched-interblock -fno-sched-spec
- -fsched-spec-load -fsched-spec-load-dangerous
- -fsingle-precision-constant -fssa -fssa-ccp -fssa-dce
- -fstrength-reduce -fstrict-aliasing -fthread-jumps
- -ftrapv -funroll-all-loops -funroll-loops
+ -falign-functions=N -falign-jumps=N
+ -falign-labels=N -falign-loops=N
+ -fbounds-check
+ -fbranch-probabilities -fcaller-saves -fcprop-registers
+ -fcse-follow-jumps -fcse-skip-blocks -fdata-sections
+ -fdelayed-branch -fdelete-null-pointer-checks
+ -fexpensive-optimizations -ffast-math -ffloat-store
+ -fforce-addr -fforce-mem -ffunction-sections
+ -fgcse -fgcse-lm -fgcse-sm
+ -finline-functions -finline-limit=N -fkeep-inline-functions
+ -fkeep-static-consts -fmerge-constants -fmerge-all-constants
+ -fmove-all-movables -fno-branch-count-reg
+ -fno-default-inline -fno-defer-pop
+ -fno-function-cse -fno-guess-branch-probability
+ -fno-inline -fno-math-errno -fno-peephole -fno-peephole2
+ -funsafe-math-optimizations -fno-trapping-math
+ -fomit-frame-pointer -foptimize-register-move
+ -foptimize-sibling-calls -fprefetch-loop-arrays
+ -freduce-all-givs -fregmove -frename-registers
+ -frerun-cse-after-loop -frerun-loop-opt
+ -fschedule-insns -fschedule-insns2
+ -fno-sched-interblock -fno-sched-spec
+ -fsched-spec-load -fsched-spec-load-dangerous
+ -fsingle-precision-constant -fssa -fssa-ccp -fssa-dce
+ -fstrength-reduce -fstrict-aliasing -fthread-jumps
+ -ftrapv -funroll-all-loops -funroll-loops
--param NAME=VALUE
-O -O0 -O1 -O2 -O3 -Os
_Preprocessor Options_
*Note Options Controlling the Preprocessor: Preprocessor Options.
- -$ -AQUESTION=ANSWER -A-QUESTION[=ANSWER]
- -C -dD -dI -dM -dN
- -DMACRO[=DEFN] -E -H
- -idirafter DIR
- -include FILE -imacros FILE
- -iprefix FILE -iwithprefix DIR
- -iwithprefixbefore DIR -isystem DIR
- -M -MM -MF -MG -MP -MQ -MT -nostdinc -P -remap
+ -$ -AQUESTION=ANSWER -A-QUESTION[=ANSWER]
+ -C -dD -dI -dM -dN
+ -DMACRO[=DEFN] -E -H
+ -idirafter DIR
+ -include FILE -imacros FILE
+ -iprefix FILE -iwithprefix DIR
+ -iwithprefixbefore DIR -isystem DIR
+ -M -MM -MF -MG -MP -MQ -MT -nostdinc -P -remap
-trigraphs -undef -UMACRO -Wp,OPTION
_Assembler Option_
_Linker Options_
*Note Options for Linking: Link Options.
- OBJECT-FILE-NAME -lLIBRARY
- -nostartfiles -nodefaultlibs -nostdlib
- -s -static -static-libgcc -shared -shared-libgcc -symbolic
- -Wl,OPTION -Xlinker OPTION
+ OBJECT-FILE-NAME -lLIBRARY
+ -nostartfiles -nodefaultlibs -nostdlib
+ -s -static -static-libgcc -shared -shared-libgcc -symbolic
+ -Wl,OPTION -Xlinker OPTION
-u SYMBOL
_Directory Options_
*Note Hardware Models and Configurations: Submodel Options.
_M680x0 Options_
- -m68000 -m68020 -m68020-40 -m68020-60 -m68030 -m68040
- -m68060 -mcpu32 -m5200 -m68881 -mbitfield -mc68000 -mc68020
- -mfpa -mnobitfield -mrtd -mshort -msoft-float -mpcrel
+ -m68000 -m68020 -m68020-40 -m68020-60 -m68030 -m68040
+ -m68060 -mcpu32 -m5200 -m68881 -mbitfield -mc68000 -mc68020
+ -mfpa -mnobitfield -mrtd -mshort -msoft-float -mpcrel
-malign-int -mstrict-align
_M68hc1x Options_
- -m6811 -m6812 -m68hc11 -m68hc12
+ -m6811 -m6812 -m68hc11 -m68hc12
-mauto-incdec -mshort -msoft-reg-count=COUNT
_VAX Options_
-mg -mgnu -munix
_SPARC Options_
- -mcpu=CPU-TYPE
- -mtune=CPU-TYPE
- -mcmodel=CODE-MODEL
- -m32 -m64
- -mapp-regs -mbroken-saverestore -mcypress
- -mfaster-structs -mflat
- -mfpu -mhard-float -mhard-quad-float
- -mimpure-text -mlive-g0 -mno-app-regs
- -mno-faster-structs -mno-flat -mno-fpu
- -mno-impure-text -mno-stack-bias -mno-unaligned-doubles
- -msoft-float -msoft-quad-float -msparclite -mstack-bias
+ -mcpu=CPU-TYPE
+ -mtune=CPU-TYPE
+ -mcmodel=CODE-MODEL
+ -m32 -m64
+ -mapp-regs -mbroken-saverestore -mcypress
+ -mfaster-structs -mflat
+ -mfpu -mhard-float -mhard-quad-float
+ -mimpure-text -mlive-g0 -mno-app-regs
+ -mno-faster-structs -mno-flat -mno-fpu
+ -mno-impure-text -mno-stack-bias -mno-unaligned-doubles
+ -msoft-float -msoft-quad-float -msparclite -mstack-bias
-msupersparc -munaligned-doubles -mv8
_Convex Options_
- -mc1 -mc2 -mc32 -mc34 -mc38
- -margcount -mnoargcount
- -mlong32 -mlong64
+ -mc1 -mc2 -mc32 -mc34 -mc38
+ -margcount -mnoargcount
+ -mlong32 -mlong64
-mvolatile-cache -mvolatile-nocache
_AMD29K Options_
- -m29000 -m29050 -mbw -mnbw -mdw -mndw
- -mlarge -mnormal -msmall
- -mkernel-registers -mno-reuse-arg-regs
- -mno-stack-check -mno-storem-bug
- -mreuse-arg-regs -msoft-float -mstack-check
+ -m29000 -m29050 -mbw -mnbw -mdw -mndw
+ -mlarge -mnormal -msmall
+ -mkernel-registers -mno-reuse-arg-regs
+ -mno-stack-check -mno-storem-bug
+ -mreuse-arg-regs -msoft-float -mstack-check
-mstorem-bug -muser-registers
_ARM Options_
- -mapcs-frame -mno-apcs-frame
- -mapcs-26 -mapcs-32
- -mapcs-stack-check -mno-apcs-stack-check
- -mapcs-float -mno-apcs-float
- -mapcs-reentrant -mno-apcs-reentrant
- -msched-prolog -mno-sched-prolog
- -mlittle-endian -mbig-endian -mwords-little-endian
- -malignment-traps -mno-alignment-traps
- -msoft-float -mhard-float -mfpe
- -mthumb-interwork -mno-thumb-interwork
- -mcpu=NAME -march=NAME -mfpe=NAME
- -mstructure-size-boundary=N
- -mbsd -mxopen -mno-symrename
- -mabort-on-noreturn
- -mlong-calls -mno-long-calls
- -msingle-pic-base -mno-single-pic-base
- -mpic-register=REG
- -mnop-fun-dllimport
- -mpoke-function-name
- -mthumb -marm
- -mtpcs-frame -mtpcs-leaf-frame
+ -mapcs-frame -mno-apcs-frame
+ -mapcs-26 -mapcs-32
+ -mapcs-stack-check -mno-apcs-stack-check
+ -mapcs-float -mno-apcs-float
+ -mapcs-reentrant -mno-apcs-reentrant
+ -msched-prolog -mno-sched-prolog
+ -mlittle-endian -mbig-endian -mwords-little-endian
+ -malignment-traps -mno-alignment-traps
+ -msoft-float -mhard-float -mfpe
+ -mthumb-interwork -mno-thumb-interwork
+ -mcpu=NAME -march=NAME -mfpe=NAME
+ -mstructure-size-boundary=N
+ -mbsd -mxopen -mno-symrename
+ -mabort-on-noreturn
+ -mlong-calls -mno-long-calls
+ -msingle-pic-base -mno-single-pic-base
+ -mpic-register=REG
+ -mnop-fun-dllimport
+ -mpoke-function-name
+ -mthumb -marm
+ -mtpcs-frame -mtpcs-leaf-frame
-mcaller-super-interworking -mcallee-super-interworking
_MN10200 Options_
-mrelax
_MN10300 Options_
- -mmult-bug -mno-mult-bug
- -mam33 -mno-am33
+ -mmult-bug -mno-mult-bug
+ -mam33 -mno-am33
-mno-crt0 -mrelax
_M32R/D Options_
- -m32rx -m32r -mcode-model=MODEL-TYPE -msdata=SDATA-TYPE
+ -m32rx -m32r -mcode-model=MODEL-TYPE -msdata=SDATA-TYPE
-G NUM
_M88K Options_
- -m88000 -m88100 -m88110 -mbig-pic
- -mcheck-zero-division -mhandle-large-shift
- -midentify-revision -mno-check-zero-division
- -mno-ocs-debug-info -mno-ocs-frame-position
- -mno-optimize-arg-area -mno-serialize-volatile
- -mno-underscores -mocs-debug-info
- -mocs-frame-position -moptimize-arg-area
- -mserialize-volatile -mshort-data-NUM -msvr3
- -msvr4 -mtrap-large-shift -muse-div-instruction
+ -m88000 -m88100 -m88110 -mbig-pic
+ -mcheck-zero-division -mhandle-large-shift
+ -midentify-revision -mno-check-zero-division
+ -mno-ocs-debug-info -mno-ocs-frame-position
+ -mno-optimize-arg-area -mno-serialize-volatile
+ -mno-underscores -mocs-debug-info
+ -mocs-frame-position -moptimize-arg-area
+ -mserialize-volatile -mshort-data-NUM -msvr3
+ -msvr4 -mtrap-large-shift -muse-div-instruction
-mversion-03.00 -mwarn-passed-structs
_RS/6000 and PowerPC Options_
- -mcpu=CPU-TYPE
- -mtune=CPU-TYPE
- -mpower -mno-power -mpower2 -mno-power2
- -mpowerpc -mpowerpc64 -mno-powerpc
- -maltivec -mno-altivec
- -mpowerpc-gpopt -mno-powerpc-gpopt
- -mpowerpc-gfxopt -mno-powerpc-gfxopt
- -mnew-mnemonics -mold-mnemonics
- -mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc
- -m64 -m32 -mxl-call -mno-xl-call -mpe
- -msoft-float -mhard-float -mmultiple -mno-multiple
- -mstring -mno-string -mupdate -mno-update
- -mfused-madd -mno-fused-madd -mbit-align -mno-bit-align
- -mstrict-align -mno-strict-align -mrelocatable
- -mno-relocatable -mrelocatable-lib -mno-relocatable-lib
- -mtoc -mno-toc -mlittle -mlittle-endian -mbig -mbig-endian
- -mcall-aix -mcall-sysv -mcall-netbsd
- -maix-struct-return -msvr4-struct-return
- -mabi=altivec -mabi=no-altivec
- -mprototype -mno-prototype
- -msim -mmvme -mads -myellowknife -memb -msdata
+ -mcpu=CPU-TYPE
+ -mtune=CPU-TYPE
+ -mpower -mno-power -mpower2 -mno-power2
+ -mpowerpc -mpowerpc64 -mno-powerpc
+ -maltivec -mno-altivec
+ -mpowerpc-gpopt -mno-powerpc-gpopt
+ -mpowerpc-gfxopt -mno-powerpc-gfxopt
+ -mnew-mnemonics -mold-mnemonics
+ -mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc
+ -m64 -m32 -mxl-call -mno-xl-call -mpe
+ -msoft-float -mhard-float -mmultiple -mno-multiple
+ -mstring -mno-string -mupdate -mno-update
+ -mfused-madd -mno-fused-madd -mbit-align -mno-bit-align
+ -mstrict-align -mno-strict-align -mrelocatable
+ -mno-relocatable -mrelocatable-lib -mno-relocatable-lib
+ -mtoc -mno-toc -mlittle -mlittle-endian -mbig -mbig-endian
+ -mcall-aix -mcall-sysv -mcall-netbsd
+ -maix-struct-return -msvr4-struct-return
+ -mabi=altivec -mabi=no-altivec
+ -mprototype -mno-prototype
+ -msim -mmvme -mads -myellowknife -memb -msdata
-msdata=OPT -mvxworks -G NUM -pthread
_RT Options_
- -mcall-lib-mul -mfp-arg-in-fpregs -mfp-arg-in-gregs
- -mfull-fp-blocks -mhc-struct-return -min-line-mul
+ -mcall-lib-mul -mfp-arg-in-fpregs -mfp-arg-in-gregs
+ -mfull-fp-blocks -mhc-struct-return -min-line-mul
-mminimum-fp-blocks -mnohc-struct-return
_MIPS Options_
- -mabicalls -march=CPU-TYPE -mtune=CPU=TYPE
- -mcpu=CPU-TYPE -membedded-data -muninit-const-in-rodata
- -membedded-pic -mfp32 -mfp64 -mfused-madd -mno-fused-madd
- -mgas -mgp32 -mgp64
- -mgpopt -mhalf-pic -mhard-float -mint64 -mips1
- -mips2 -mips3 -mips4 -mlong64 -mlong32 -mlong-calls -mmemcpy
- -mmips-as -mmips-tfile -mno-abicalls
- -mno-embedded-data -mno-uninit-const-in-rodata
- -mno-embedded-pic -mno-gpopt -mno-long-calls
- -mno-memcpy -mno-mips-tfile -mno-rnames -mno-stats
- -mrnames -msoft-float
- -m4650 -msingle-float -mmad
- -mstats -EL -EB -G NUM -nocpp
- -mabi=32 -mabi=n32 -mabi=64 -mabi=eabi
+ -mabicalls -march=CPU-TYPE -mtune=CPU=TYPE
+ -mcpu=CPU-TYPE -membedded-data -muninit-const-in-rodata
+ -membedded-pic -mfp32 -mfp64 -mfused-madd -mno-fused-madd
+ -mgas -mgp32 -mgp64
+ -mgpopt -mhalf-pic -mhard-float -mint64 -mips1
+ -mips2 -mips3 -mips4 -mlong64 -mlong32 -mlong-calls -mmemcpy
+ -mmips-as -mmips-tfile -mno-abicalls
+ -mno-embedded-data -mno-uninit-const-in-rodata
+ -mno-embedded-pic -mno-gpopt -mno-long-calls
+ -mno-memcpy -mno-mips-tfile -mno-rnames -mno-stats
+ -mrnames -msoft-float
+ -m4650 -msingle-float -mmad
+ -mstats -EL -EB -G NUM -nocpp
+ -mabi=32 -mabi=n32 -mabi=64 -mabi=eabi
-mfix7000 -mno-crt0 -mflush-func=FUNC -mno-flush-func
_i386 and x86-64 Options_
- -mcpu=CPU-TYPE -march=CPU-TYPE -mfpmath=UNIT
- -masm=DIALECT -mno-fancy-math-387
- -mno-fp-ret-in-387 -msoft-float -msvr3-shlib
- -mno-wide-multiply -mrtd -malign-double
- -mpreferred-stack-boundary=NUM
- -mmmx -msse -msse2 -m3dnow
- -mthreads -mno-align-stringops -minline-all-stringops
- -mpush-args -maccumulate-outgoing-args -m128bit-long-double
- -m96bit-long-double -mregparm=NUM -momit-leaf-frame-pointer
+ -mcpu=CPU-TYPE -march=CPU-TYPE -mfpmath=UNIT
+ -masm=DIALECT -mno-fancy-math-387
+ -mno-fp-ret-in-387 -msoft-float -msvr3-shlib
+ -mno-wide-multiply -mrtd -malign-double
+ -mpreferred-stack-boundary=NUM
+ -mmmx -msse -msse2 -m3dnow
+ -mthreads -mno-align-stringops -minline-all-stringops
+ -mpush-args -maccumulate-outgoing-args -m128bit-long-double
+ -m96bit-long-double -mregparm=NUM -momit-leaf-frame-pointer
-mno-red-zone
- -mcmodel=CODE-MODEL
+ -mcmodel=CODE-MODEL
-m32 -m64
_HPPA Options_
- -march=ARCHITECTURE-TYPE
- -mbig-switch -mdisable-fpregs -mdisable-indexing
- -mfast-indirect-calls -mgas -mjump-in-delay
- -mlong-load-store -mno-big-switch -mno-disable-fpregs
- -mno-disable-indexing -mno-fast-indirect-calls -mno-gas
- -mno-jump-in-delay -mno-long-load-store
- -mno-portable-runtime -mno-soft-float
- -mno-space-regs -msoft-float -mpa-risc-1-0
- -mpa-risc-1-1 -mpa-risc-2-0 -mportable-runtime
+ -march=ARCHITECTURE-TYPE
+ -mbig-switch -mdisable-fpregs -mdisable-indexing
+ -mfast-indirect-calls -mgas -mjump-in-delay
+ -mlong-load-store -mno-big-switch -mno-disable-fpregs
+ -mno-disable-indexing -mno-fast-indirect-calls -mno-gas
+ -mno-jump-in-delay -mno-long-load-store
+ -mno-portable-runtime -mno-soft-float
+ -mno-space-regs -msoft-float -mpa-risc-1-0
+ -mpa-risc-1-1 -mpa-risc-2-0 -mportable-runtime
-mschedule=CPU-TYPE -mspace-regs
_Intel 960 Options_
- -mCPU-TYPE -masm-compat -mclean-linkage
- -mcode-align -mcomplex-addr -mleaf-procedures
- -mic-compat -mic2.0-compat -mic3.0-compat
- -mintel-asm -mno-clean-linkage -mno-code-align
- -mno-complex-addr -mno-leaf-procedures
- -mno-old-align -mno-strict-align -mno-tail-call
- -mnumerics -mold-align -msoft-float -mstrict-align
+ -mCPU-TYPE -masm-compat -mclean-linkage
+ -mcode-align -mcomplex-addr -mleaf-procedures
+ -mic-compat -mic2.0-compat -mic3.0-compat
+ -mintel-asm -mno-clean-linkage -mno-code-align
+ -mno-complex-addr -mno-leaf-procedures
+ -mno-old-align -mno-strict-align -mno-tail-call
+ -mnumerics -mold-align -msoft-float -mstrict-align
-mtail-call
_DEC Alpha Options_
- -mno-fp-regs -msoft-float -malpha-as -mgas
- -mieee -mieee-with-inexact -mieee-conformant
- -mfp-trap-mode=MODE -mfp-rounding-mode=MODE
- -mtrap-precision=MODE -mbuild-constants
- -mcpu=CPU-TYPE -mtune=CPU-TYPE
- -mbwx -mmax -mfix -mcix
- -mfloat-vax -mfloat-ieee
- -mexplicit-relocs -msmall-data -mlarge-data
+ -mno-fp-regs -msoft-float -malpha-as -mgas
+ -mieee -mieee-with-inexact -mieee-conformant
+ -mfp-trap-mode=MODE -mfp-rounding-mode=MODE
+ -mtrap-precision=MODE -mbuild-constants
+ -mcpu=CPU-TYPE -mtune=CPU-TYPE
+ -mbwx -mmax -mfix -mcix
+ -mfloat-vax -mfloat-ieee
+ -mexplicit-relocs -msmall-data -mlarge-data
-mmemory-latency=TIME
_DEC Alpha/VMS Options_
-mrelax -mh -ms -mint32 -malign-300
_SH Options_
- -m1 -m2 -m3 -m3e
- -m4-nofpu -m4-single-only -m4-single -m4
- -m5-64media -m5-64media-nofpu
- -m5-32media -m5-32media-nofpu
- -m5-compact -m5-compact-nofpu
- -mb -ml -mdalign -mrelax
- -mbigtable -mfmovd -mhitachi -mnomacsave
- -mieee -misize -mpadstruct -mspace
+ -m1 -m2 -m3 -m3e
+ -m4-nofpu -m4-single-only -m4-single -m4
+ -m5-64media -m5-64media-nofpu
+ -m5-32media -m5-32media-nofpu
+ -m5-compact -m5-compact-nofpu
+ -mb -ml -mdalign -mrelax
+ -mbigtable -mfmovd -mhitachi -mnomacsave
+ -mieee -misize -mpadstruct -mspace
-mprefergot -musermode
_System V Options_
-Qy -Qn -YP,PATHS -Ym,DIR
_ARC Options_
- -EB -EL
- -mmangle-cpu -mcpu=CPU -mtext=TEXT-SECTION
+ -EB -EL
+ -mmangle-cpu -mcpu=CPU -mtext=TEXT-SECTION
-mdata=DATA-SECTION -mrodata=READONLY-DATA-SECTION
_TMS320C3x/C4x Options_
- -mcpu=CPU -mbig -msmall -mregparm -mmemparm
- -mfast-fix -mmpyi -mbk -mti -mdp-isr-reload
- -mrpts=COUNT -mrptb -mdb -mloop-unsigned
+ -mcpu=CPU -mbig -msmall -mregparm -mmemparm
+ -mfast-fix -mmpyi -mbk -mti -mdp-isr-reload
+ -mrpts=COUNT -mrptb -mdb -mloop-unsigned
-mparallel-insns -mparallel-mpy -mpreserve-float
_V850 Options_
- -mlong-calls -mno-long-calls -mep -mno-ep
- -mprolog-function -mno-prolog-function -mspace
- -mtda=N -msda=N -mzda=N
+ -mlong-calls -mno-long-calls -mep -mno-ep
+ -mprolog-function -mno-prolog-function -mspace
+ -mtda=N -msda=N -mzda=N
-mv850 -mbig-switch
_NS32K Options_
- -m32032 -m32332 -m32532 -m32081 -m32381
- -mmult-add -mnomult-add -msoft-float -mrtd -mnortd
- -mregparam -mnoregparam -msb -mnosb
+ -m32032 -m32332 -m32532 -m32081 -m32381
+ -mmult-add -mnomult-add -msoft-float -mrtd -mnortd
+ -mregparam -mnoregparam -msb -mnosb
-mbitfield -mnobitfield -mhimem -mnohimem
_AVR Options_
- -mmcu=MCU -msize -minit-stack=N -mno-interrupts
+ -mmcu=MCU -msize -minit-stack=N -mno-interrupts
-mcall-prologues -mno-tablejump -mtiny-stack
_MCore Options_
- -mhardlit -mno-hardlit -mdiv -mno-div -mrelax-immediates
- -mno-relax-immediates -mwide-bitfields -mno-wide-bitfields
- -m4byte-functions -mno-4byte-functions -mcallgraph-data
- -mno-callgraph-data -mslow-bytes -mno-slow-bytes -mno-lsim
+ -mhardlit -mno-hardlit -mdiv -mno-div -mrelax-immediates
+ -mno-relax-immediates -mwide-bitfields -mno-wide-bitfields
+ -m4byte-functions -mno-4byte-functions -mcallgraph-data
+ -mno-callgraph-data -mslow-bytes -mno-slow-bytes -mno-lsim
-mlittle-endian -mbig-endian -m210 -m340 -mstack-increment
_MMIX Options_
- -mlibfuncs -mno-libfuncs -mepsilon -mno-epsilon -mabi=gnu
- -mabi=mmixware -mzero-extend -mknuthdiv -mtoplevel-symbols
- -melf -mbranch-predict -mno-branch-predict -mbase-addresses
+ -mlibfuncs -mno-libfuncs -mepsilon -mno-epsilon -mabi=gnu
+ -mabi=mmixware -mzero-extend -mknuthdiv -mtoplevel-symbols
+ -melf -mbranch-predict -mno-branch-predict -mbase-addresses
-mno-base-addresses
_IA-64 Options_
- -mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic
- -mvolatile-asm-stop -mb-step -mregister-names -mno-sdata
- -mconstant-gp -mauto-pic -minline-divide-min-latency
- -minline-divide-max-throughput -mno-dwarf2-asm
+ -mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic
+ -mvolatile-asm-stop -mb-step -mregister-names -mno-sdata
+ -mconstant-gp -mauto-pic -minline-divide-min-latency
+ -minline-divide-max-throughput -mno-dwarf2-asm
-mfixed-range=REGISTER-RANGE
_D30V Options_
- -mextmem -mextmemory -monchip -mno-asm-optimize
+ -mextmem -mextmemory -monchip -mno-asm-optimize
-masm-optimize -mbranch-cost=N -mcond-exec=N
_S/390 and zSeries Options_
- -mhard-float -msoft-float -mbackchain -mno-backchain
- -msmall-exec -mno-small-exec -mmvcle -mno-mvcle
+ -mhard-float -msoft-float -mbackchain -mno-backchain
+ -msmall-exec -mno-small-exec -mmvcle -mno-mvcle
-m64 -m31 -mdebug -mno-debug
_CRIS Options_
- -mcpu=CPU -march=CPU -mtune=CPU
- -mmax-stack-frame=N -melinux-stacksize=N
- -metrax4 -metrax100 -mpdebug -mcc-init -mno-side-effects
- -mstack-align -mdata-align -mconst-align
- -m32-bit -m16-bit -m8-bit -mno-prologue-epilogue -mno-gotplt
+ -mcpu=CPU -march=CPU -mtune=CPU
+ -mmax-stack-frame=N -melinux-stacksize=N
+ -metrax4 -metrax100 -mpdebug -mcc-init -mno-side-effects
+ -mstack-align -mdata-align -mconst-align
+ -m32-bit -m16-bit -m8-bit -mno-prologue-epilogue -mno-gotplt
-melf -maout -melinux -mlinux -sim -sim2
_PDP-11 Options_
- -mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45 -m10
- -mbcopy -mbcopy-builtin -mint32 -mno-int16
- -mint16 -mno-int32 -mfloat32 -mno-float64
- -mfloat64 -mno-float32 -mabshi -mno-abshi
- -mbranch-expensive -mbranch-cheap
+ -mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45 -m10
+ -mbcopy -mbcopy-builtin -mint32 -mno-int16
+ -mint16 -mno-int32 -mfloat32 -mno-float64
+ -mfloat64 -mno-float32 -mabshi -mno-abshi
+ -mbranch-expensive -mbranch-cheap
-msplit -mno-split -munix-asm -mdec-asm
_Xstormy16 Options_
-msim
_Xtensa Options_
- -mbig-endian -mlittle-endian
- -mdensity -mno-density
- -mmac16 -mno-mac16
- -mmul16 -mno-mul16
- -mmul32 -mno-mul32
- -mnsa -mno-nsa
- -mminmax -mno-minmax
- -msext -mno-sext
- -mbooleans -mno-booleans
- -mhard-float -msoft-float
- -mfused-madd -mno-fused-madd
- -mserialize-volatile -mno-serialize-volatile
- -mtext-section-literals -mno-text-section-literals
- -mtarget-align -mno-target-align
+ -mbig-endian -mlittle-endian
+ -mdensity -mno-density
+ -mmac16 -mno-mac16
+ -mmul16 -mno-mul16
+ -mmul32 -mno-mul32
+ -mnsa -mno-nsa
+ -mminmax -mno-minmax
+ -msext -mno-sext
+ -mbooleans -mno-booleans
+ -mhard-float -msoft-float
+ -mfused-madd -mno-fused-madd
+ -mserialize-volatile -mno-serialize-volatile
+ -mtext-section-literals -mno-text-section-literals
+ -mtarget-align -mno-target-align
-mlongcalls -mno-longcalls
_Code Generation Options_
*Note Options for Code Generation Conventions: Code Gen Options.
- -fcall-saved-REG -fcall-used-REG
- -ffixed-REG -fexceptions
- -fnon-call-exceptions -funwind-tables
- -fasynchronous-unwind-tables
- -finhibit-size-directive -finstrument-functions
- -fno-common -fno-ident -fno-gnu-linker
- -fpcc-struct-return -fpic -fPIC
- -freg-struct-return -fshared-data -fshort-enums
- -fshort-double -fshort-wchar -fvolatile
- -fvolatile-global -fvolatile-static
- -fverbose-asm -fpack-struct -fstack-check
- -fstack-limit-register=REG -fstack-limit-symbol=SYM
- -fargument-alias -fargument-noalias
+ -fcall-saved-REG -fcall-used-REG
+ -ffixed-REG -fexceptions
+ -fnon-call-exceptions -funwind-tables
+ -fasynchronous-unwind-tables
+ -finhibit-size-directive -finstrument-functions
+ -fno-common -fno-ident -fno-gnu-linker
+ -fpcc-struct-return -fpic -fPIC
+ -freg-struct-return -fshared-data -fshort-enums
+ -fshort-double -fshort-wchar -fvolatile
+ -fvolatile-global -fvolatile-static
+ -fverbose-asm -fpack-struct -fstack-check
+ -fstack-limit-register=REG -fstack-limit-symbol=SYM
+ -fargument-alias -fargument-noalias
-fargument-noalias-global -fleading-underscore
\1f
File: gcc.info, Node: Overall Options, Next: Invoking G++, Prev: Option Summary, Up: Invoking GCC
-Options Controlling the Kind of Output
-======================================
+3.2 Options Controlling the Kind of Output
+==========================================
- Compilation can involve up to four stages: preprocessing, compilation
+Compilation can involve up to four stages: preprocessing, compilation
proper, assembly and linking, always in that order. The first three
stages apply to an individual source file, and end by producing an
object file; linking combines all the object files (those newly
\1f
File: gcc.info, Node: Invoking G++, Next: C Dialect Options, Prev: Overall Options, Up: Invoking GCC
-Compiling C++ Programs
-======================
+3.3 Compiling C++ Programs
+==========================
- C++ source files conventionally use one of the suffixes `.C', `.cc',
+C++ source files conventionally use one of the suffixes `.C', `.cc',
`.cpp', `.c++', `.cp', or `.cxx'; preprocessed C++ files use the suffix
`.ii'. GCC recognizes files with these names and compiles them as C++
programs even if you call the compiler the same way as for compiling C
Dialect: C++ Dialect Options, for explanations of options that are
meaningful only for C++ programs.
+\1f
+File: gcc.info, Node: C Dialect Options, Next: C++ Dialect Options, Prev: Invoking G++, Up: Invoking GCC
+
+3.4 Options Controlling C Dialect
+=================================
+
+The following options control the dialect of C (or languages derived
+from C, such as C++ and Objective-C) that the compiler accepts:
+
+`-ansi'
+ In C mode, support all ISO C89 programs. In C++ mode, remove GNU
+ extensions that conflict with ISO C++.
+
+ This turns off certain features of GCC that are incompatible with
+ ISO C89 (when compiling C code), or of standard C++ (when
+ compiling C++ code), such as the `asm' and `typeof' keywords, and
+ predefined macros such as `unix' and `vax' that identify the type
+ of system you are using. It also enables the undesirable and
+ rarely used ISO trigraph feature. For the C compiler, it disables
+ recognition of C++ style `//' comments as well as the `inline'
+ keyword.
+
+ The alternate keywords `__asm__', `__extension__', `__inline__'
+ and `__typeof__' continue to work despite `-ansi'. You would not
+ want to use them in an ISO C program, of course, but it is useful
+ to put them in header files that might be included in compilations
+ done with `-ansi'. Alternate predefined macros such as `__unix__'
+ and `__vax__' are also available, with or without `-ansi'.
+
+ The `-ansi' option does not cause non-ISO programs to be rejected
+ gratuitously. For that, `-pedantic' is required in addition to
+ `-ansi'. *Note Warning Options::.
+
+ The macro `__STRICT_ANSI__' is predefined when the `-ansi' option
+ is used. Some header files may notice this macro and refrain from
+ declaring certain functions or defining certain macros that the
+ ISO standard doesn't call for; this is to avoid interfering with
+ any programs that might use these names for other things.
+
+ Functions which would normally be built in but do not have
+ semantics defined by ISO C (such as `alloca' and `ffs') are not
+ built-in functions with `-ansi' is used. *Note Other built-in
+ functions provided by GCC: Other Builtins, for details of the
+ functions affected.
+
+`-std='
+ Determine the language standard. This option is currently only
+ supported when compiling C. A value for this option must be
+ provided; possible values are
+
+ `c89'
+ `iso9899:1990'
+ ISO C89 (same as `-ansi').
+
+ `iso9899:199409'
+ ISO C89 as modified in amendment 1.
+
+ `c99'
+ `c9x'
+ `iso9899:1999'
+ `iso9899:199x'
+ ISO C99. Note that this standard is not yet fully supported;
+ see `http://gcc.gnu.org/gcc-3.1/c99status.html' for more
+ information. The names `c9x' and `iso9899:199x' are
+ deprecated.
+
+ `gnu89'
+ Default, ISO C89 plus GNU extensions (including some C99
+ features).
+
+ `gnu99'
+
+ `gnu9x'
+ ISO C99 plus GNU extensions. When ISO C99 is fully
+ implemented in GCC, this will become the default. The name
+ `gnu9x' is deprecated.
+
+
+ Even when this option is not specified, you can still use some of
+ the features of newer standards in so far as they do not conflict
+ with previous C standards. For example, you may use
+ `__restrict__' even when `-std=c99' is not specified.
+
+ The `-std' options specifying some version of ISO C have the same
+ effects as `-ansi', except that features that were not in ISO C89
+ but are in the specified version (for example, `//' comments and
+ the `inline' keyword in ISO C99) are not disabled.
+
+ *Note Language Standards Supported by GCC: Standards, for details
+ of these standard versions.
+
+`-aux-info FILENAME'
+ Output to the given filename prototyped declarations for all
+ functions declared and/or defined in a translation unit, including
+ those in header files. This option is silently ignored in any
+ language other than C.
+
+ Besides declarations, the file indicates, in comments, the origin
+ of each declaration (source file and line), whether the
+ declaration was implicit, prototyped or unprototyped (`I', `N' for
+ new or `O' for old, respectively, in the first character after the
+ line number and the colon), and whether it came from a declaration
+ or a definition (`C' or `F', respectively, in the following
+ character). In the case of function definitions, a K&R-style list
+ of arguments followed by their declarations is also provided,
+ inside comments, after the declaration.
+
+`-fno-asm'
+ Do not recognize `asm', `inline' or `typeof' as a keyword, so that
+ code can use these words as identifiers. You can use the keywords
+ `__asm__', `__inline__' and `__typeof__' instead. `-ansi' implies
+ `-fno-asm'.
+
+ In C++, this switch only affects the `typeof' keyword, since `asm'
+ and `inline' are standard keywords. You may want to use the
+ `-fno-gnu-keywords' flag instead, which has the same effect. In
+ C99 mode (`-std=c99' or `-std=gnu99'), this switch only affects
+ the `asm' and `typeof' keywords, since `inline' is a standard
+ keyword in ISO C99.
+
+`-fno-builtin'
+`-fno-builtin-FUNCTION (C and Objective-C only)'
+ Don't recognize built-in functions that do not begin with
+ `__builtin_' as prefix. *Note Other built-in functions provided
+ by GCC: Other Builtins, for details of the functions affected,
+ including those which are not built-in functions when `-ansi' or
+ `-std' options for strict ISO C conformance are used because they
+ do not have an ISO standard meaning.
+
+ GCC normally generates special code to handle certain built-in
+ functions more efficiently; for instance, calls to `alloca' may
+ become single instructions that adjust the stack directly, and
+ calls to `memcpy' may become inline copy loops. The resulting
+ code is often both smaller and faster, but since the function
+ calls no longer appear as such, you cannot set a breakpoint on
+ those calls, nor can you change the behavior of the functions by
+ linking with a different library.
+
+ In C++, `-fno-builtin' is always in effect. The `-fbuiltin'
+ option has no effect. Therefore, in C++, the only way to get the
+ optimization benefits of built-in functions is to call the function
+ using the `__builtin_' prefix. The GNU C++ Standard Library uses
+ built-in functions to implement many functions (like
+ `std::strchr'), so that you automatically get efficient code.
+
+ With the `-fno-builtin-FUNCTION' option, not available when
+ compiling C++, only the built-in function FUNCTION is disabled.
+ FUNCTION must not begin with `__builtin_'. If a function is named
+ this is not built-in in this version of GCC, this option is
+ ignored. There is no corresponding `-fbuiltin-FUNCTION' option;
+ if you wish to enable built-in functions selectively when using
+ `-fno-builtin' or `-ffreestanding', you may define macros such as:
+
+ #define abs(n) __builtin_abs ((n))
+ #define strcpy(d, s) __builtin_strcpy ((d), (s))
+
+`-fhosted'
+ Assert that compilation takes place in a hosted environment. This
+ implies `-fbuiltin'. A hosted environment is one in which the
+ entire standard library is available, and in which `main' has a
+ return type of `int'. Examples are nearly everything except a
+ kernel. This is equivalent to `-fno-freestanding'.
+
+`-ffreestanding'
+ Assert that compilation takes place in a freestanding environment.
+ This implies `-fno-builtin'. A freestanding environment is one in
+ which the standard library may not exist, and program startup may
+ not necessarily be at `main'. The most obvious example is an OS
+ kernel. This is equivalent to `-fno-hosted'.
+
+ *Note Language Standards Supported by GCC: Standards, for details
+ of freestanding and hosted environments.
+
+`-trigraphs'
+ Support ISO C trigraphs. The `-ansi' option (and `-std' options
+ for strict ISO C conformance) implies `-trigraphs'.
+
+`-no-integrated-cpp'
+ Invoke the external cpp during compilation. The default is to use
+ the integrated cpp (internal cpp). This option also allows a
+ user-supplied cpp via the `-B' option. This flag is applicable in
+ both C and C++ modes.
+
+ We do not guarantee to retain this option in future, and we may
+ change its semantics.
+
+`-traditional'
+ Attempt to support some aspects of traditional C compilers.
+ Specifically:
+
+ * All `extern' declarations take effect globally even if they
+ are written inside of a function definition. This includes
+ implicit declarations of functions.
+
+ * The newer keywords `typeof', `inline', `signed', `const' and
+ `volatile' are not recognized. (You can still use the
+ alternative keywords such as `__typeof__', `__inline__', and
+ so on.)
+
+ * Comparisons between pointers and integers are always allowed.
+
+ * Integer types `unsigned short' and `unsigned char' promote to
+ `unsigned int'.
+
+ * Out-of-range floating point literals are not an error.
+
+ * Certain constructs which ISO regards as a single invalid
+ preprocessing number, such as `0xe-0xd', are treated as
+ expressions instead.
+
+ * String "constants" are not necessarily constant; they are
+ stored in writable space, and identical looking constants are
+ allocated separately. (This is the same as the effect of
+ `-fwritable-strings'.)
+
+ * All automatic variables not declared `register' are preserved
+ by `longjmp'. Ordinarily, GNU C follows ISO C: automatic
+ variables not declared `volatile' may be clobbered.
+
+ * The character escape sequences `\x' and `\a' evaluate as the
+ literal characters `x' and `a' respectively. Without
+ `-traditional', `\x' is a prefix for the hexadecimal
+ representation of a character, and `\a' produces a bell.
+
+ This option is deprecated and may be removed.
+
+ You may wish to use `-fno-builtin' as well as `-traditional' if
+ your program uses names that are normally GNU C built-in functions
+ for other purposes of its own.
+
+ You cannot use `-traditional' if you include any header files that
+ rely on ISO C features. Some vendors are starting to ship systems
+ with ISO C header files and you cannot use `-traditional' on such
+ systems to compile files that include any system headers.
+
+ The `-traditional' option also enables `-traditional-cpp'.
+
+`-traditional-cpp'
+ Attempt to support some aspects of traditional C preprocessors.
+ See the GNU CPP manual for details.
+
+`-fcond-mismatch'
+ Allow conditional expressions with mismatched types in the second
+ and third arguments. The value of such an expression is void.
+ This option is not supported for C++.
+
+`-funsigned-char'
+ Let the type `char' be unsigned, like `unsigned char'.
+
+ Each kind of machine has a default for what `char' should be. It
+ is either like `unsigned char' by default or like `signed char' by
+ default.
+
+ Ideally, a portable program should always use `signed char' or
+ `unsigned char' when it depends on the signedness of an object.
+ But many programs have been written to use plain `char' and expect
+ it to be signed, or expect it to be unsigned, depending on the
+ machines they were written for. This option, and its inverse, let
+ you make such a program work with the opposite default.
+
+ The type `char' is always a distinct type from each of `signed
+ char' or `unsigned char', even though its behavior is always just
+ like one of those two.
+
+`-fsigned-char'
+ Let the type `char' be signed, like `signed char'.
+
+ Note that this is equivalent to `-fno-unsigned-char', which is the
+ negative form of `-funsigned-char'. Likewise, the option
+ `-fno-signed-char' is equivalent to `-funsigned-char'.
+
+`-fsigned-bitfields'
+`-funsigned-bitfields'
+`-fno-signed-bitfields'
+`-fno-unsigned-bitfields'
+ These options control whether a bit-field is signed or unsigned,
+ when the declaration does not use either `signed' or `unsigned'.
+ By default, such a bit-field is signed, because this is
+ consistent: the basic integer types such as `int' are signed types.
+
+ However, when `-traditional' is used, bit-fields are all unsigned
+ no matter what.
+
+`-fwritable-strings'
+ Store string constants in the writable data segment and don't
+ uniquize them. This is for compatibility with old programs which
+ assume they can write into string constants. The option
+ `-traditional' also has this effect.
+
+ Writing into string constants is a very bad idea; "constants"
+ should be constant.
+
+`-fallow-single-precision'
+ Do not promote single precision math operations to double
+ precision, even when compiling with `-traditional'.
+
+ Traditional K&R C promotes all floating point operations to double
+ precision, regardless of the sizes of the operands. On the
+ architecture for which you are compiling, single precision may be
+ faster than double precision. If you must use `-traditional',
+ but want to use single precision operations when the operands are
+ single precision, use this option. This option has no effect
+ when compiling with ISO or GNU C conventions (the default).
+
+\1f
+File: gcc.info, Node: C++ Dialect Options, Next: Objective-C Dialect Options, Prev: C Dialect Options, Up: Invoking GCC
+
+3.5 Options Controlling C++ Dialect
+===================================
+
+This section describes the command-line options that are only meaningful
+for C++ programs; but you can also use most of the GNU compiler options
+regardless of what language your program is in. For example, you might
+compile a file `firstClass.C' like this:
+
+ g++ -g -frepo -O -c firstClass.C
+
+In this example, only `-frepo' is an option meant only for C++
+programs; you can use the other options with any language supported by
+GCC.
+
+ Here is a list of options that are _only_ for compiling C++ programs:
+
+`-fno-access-control'
+ Turn off all access checking. This switch is mainly useful for
+ working around bugs in the access control code.
+
+`-fcheck-new'
+ Check that the pointer returned by `operator new' is non-null
+ before attempting to modify the storage allocated. The current
+ Working Paper requires that `operator new' never return a null
+ pointer, so this check is normally unnecessary.
+
+ An alternative to using this option is to specify that your
+ `operator new' does not throw any exceptions; if you declare it
+ `throw()', G++ will check the return value. See also `new
+ (nothrow)'.
+
+`-fconserve-space'
+ Put uninitialized or runtime-initialized global variables into the
+ common segment, as C does. This saves space in the executable at
+ the cost of not diagnosing duplicate definitions. If you compile
+ with this flag and your program mysteriously crashes after
+ `main()' has completed, you may have an object that is being
+ destroyed twice because two definitions were merged.
+
+ This option is no longer useful on most targets, now that support
+ has been added for putting variables into BSS without making them
+ common.
+
+`-fno-const-strings'
+ Give string constants type `char *' instead of type `const char
+ *'. By default, G++ uses type `const char *' as required by the
+ standard. Even if you use `-fno-const-strings', you cannot
+ actually modify the value of a string constant, unless you also use
+ `-fwritable-strings'.
+
+ This option might be removed in a future release of G++. For
+ maximum portability, you should structure your code so that it
+ works with string constants that have type `const char *'.
+
+`-fdollars-in-identifiers'
+ Accept `$' in identifiers. You can also explicitly prohibit use of
+ `$' with the option `-fno-dollars-in-identifiers'. (GNU C allows
+ `$' by default on most target systems, but there are a few
+ exceptions.) Traditional C allowed the character `$' to form part
+ of identifiers. However, ISO C and C++ forbid `$' in identifiers.
+
+`-fno-elide-constructors'
+ The C++ standard allows an implementation to omit creating a
+ temporary which is only used to initialize another object of the
+ same type. Specifying this option disables that optimization, and
+ forces G++ to call the copy constructor in all cases.
+
+`-fno-enforce-eh-specs'
+ Don't check for violation of exception specifications at runtime.
+ This option violates the C++ standard, but may be useful for
+ reducing code size in production builds, much like defining
+ `NDEBUG'. The compiler will still optimize based on the exception
+ specifications.
+
+`-fexternal-templates'
+ Cause `#pragma interface' and `implementation' to apply to
+ template instantiation; template instances are emitted or not
+ according to the location of the template definition. *Note
+ Template Instantiation::, for more information.
+
+ This option is deprecated.
+
+`-falt-external-templates'
+ Similar to `-fexternal-templates', but template instances are
+ emitted or not according to the place where they are first
+ instantiated. *Note Template Instantiation::, for more
+ information.
+
+ This option is deprecated.
+
+`-ffor-scope'
+`-fno-for-scope'
+ If `-ffor-scope' is specified, the scope of variables declared in
+ a for-init-statement is limited to the `for' loop itself, as
+ specified by the C++ standard. If `-fno-for-scope' is specified,
+ the scope of variables declared in a for-init-statement extends to
+ the end of the enclosing scope, as was the case in old versions of
+ G++, and other (traditional) implementations of C++.
+
+ The default if neither flag is given to follow the standard, but
+ to allow and give a warning for old-style code that would
+ otherwise be invalid, or have different behavior.
+
+`-fno-gnu-keywords'
+ Do not recognize `typeof' as a keyword, so that code can use this
+ word as an identifier. You can use the keyword `__typeof__'
+ instead. `-ansi' implies `-fno-gnu-keywords'.
+
+`-fno-implicit-templates'
+ Never emit code for non-inline templates which are instantiated
+ implicitly (i.e. by use); only emit code for explicit
+ instantiations. *Note Template Instantiation::, for more
+ information.
+
+`-fno-implicit-inline-templates'
+ Don't emit code for implicit instantiations of inline templates,
+ either. The default is to handle inlines differently so that
+ compiles with and without optimization will need the same set of
+ explicit instantiations.
+
+`-fno-implement-inlines'
+ To save space, do not emit out-of-line copies of inline functions
+ controlled by `#pragma implementation'. This will cause linker
+ errors if these functions are not inlined everywhere they are
+ called.
+
+`-fms-extensions'
+ Disable pedantic warnings about constructs used in MFC, such as
+ implicit int and getting a pointer to member function via
+ non-standard syntax.
+
+`-fno-nonansi-builtins'
+ Disable built-in declarations of functions that are not mandated by
+ ANSI/ISO C. These include `ffs', `alloca', `_exit', `index',
+ `bzero', `conjf', and other related functions.
+
+`-fno-operator-names'
+ Do not treat the operator name keywords `and', `bitand', `bitor',
+ `compl', `not', `or' and `xor' as synonyms as keywords.
+
+`-fno-optional-diags'
+ Disable diagnostics that the standard says a compiler does not
+ need to issue. Currently, the only such diagnostic issued by G++
+ is the one for a name having multiple meanings within a class.
+
+`-fpermissive'
+ Downgrade messages about nonconformant code from errors to
+ warnings. By default, G++ effectively sets `-pedantic-errors'
+ without `-pedantic'; this option reverses that. This behavior and
+ this option are superseded by `-pedantic', which works as it does
+ for GNU C.
+
+`-frepo'
+ Enable automatic template instantiation at link time. This option
+ also implies `-fno-implicit-templates'. *Note Template
+ Instantiation::, for more information.
+
+`-fno-rtti'
+ Disable generation of information about every class with virtual
+ functions for use by the C++ runtime type identification features
+ (`dynamic_cast' and `typeid'). If you don't use those parts of
+ the language, you can save some space by using this flag. Note
+ that exception handling uses the same information, but it will
+ generate it as needed.
+
+`-fstats'
+ Emit statistics about front-end processing at the end of the
+ compilation. This information is generally only useful to the G++
+ development team.
+
+`-ftemplate-depth-N'
+ Set the maximum instantiation depth for template classes to N. A
+ limit on the template instantiation depth is needed to detect
+ endless recursions during template class instantiation. ANSI/ISO
+ C++ conforming programs must not rely on a maximum depth greater
+ than 17.
+
+`-fuse-cxa-atexit'
+ Register destructors for objects with static storage duration with
+ the `__cxa_atexit' function rather than the `atexit' function.
+ This option is required for fully standards-compliant handling of
+ static destructors, but will only work if your C library supports
+ `__cxa_atexit'.
+
+`-fvtable-gc'
+ Emit special relocations for vtables and virtual function
+ references so that the linker can identify unused virtual
+ functions and zero out vtable slots that refer to them. This is
+ most useful with `-ffunction-sections' and `-Wl,--gc-sections', in
+ order to also discard the functions themselves.
+
+ This optimization requires GNU as and GNU ld. Not all systems
+ support this option. `-Wl,--gc-sections' is ignored without
+ `-static'.
+
+`-fno-weak'
+ Do not use weak symbol support, even if it is provided by the
+ linker. By default, G++ will use weak symbols if they are
+ available. This option exists only for testing, and should not be
+ used by end-users; it will result in inferior code and has no
+ benefits. This option may be removed in a future release of G++.
+
+`-nostdinc++'
+ Do not search for header files in the standard directories
+ specific to C++, but do still search the other standard
+ directories. (This option is used when building the C++ library.)
+
+ In addition, these optimization, warning, and code generation options
+have meanings only for C++ programs:
+
+`-fno-default-inline'
+ Do not assume `inline' for functions defined inside a class scope.
+ *Note Options That Control Optimization: Optimize Options. Note
+ that these functions will have linkage like inline functions; they
+ just won't be inlined by default.
+
+`-Wabi (C++ only)'
+ Warn when G++ generates code that is probably not compatible with
+ the vendor-neutral C++ ABI. Although an effort has been made to
+ warn about all such cases, there are probably some cases that are
+ not warned about, even though G++ is generating incompatible code.
+ There may also be cases where warnings are emitted even though the
+ code that is generated will be compatible.
+
+ You should rewrite your code to avoid these warnings if you are
+ concerned about the fact that code generated by G++ may not be
+ binary compatible with code generated by other compilers.
+
+ The known incompatibilites at this point include:
+
+ * Incorrect handling of tail-padding for bit-fields. G++ may
+ attempt to pack data into the same byte as a base class. For
+ example:
+
+ struct A { virtual void f(); int f1 : 1; };
+ struct B : public A { int f2 : 1; };
+
+ In this case, G++ will place `B::f2' into the same byte
+ as`A::f1'; other compilers will not. You can avoid this
+ problem by explicitly padding `A' so that its size is a
+ multiple of the byte size on your platform; that will cause
+ G++ and other compilers to layout `B' identically.
+
+ * Incorrect handling of tail-padding for virtual bases. G++
+ does not use tail padding when laying out virtual bases. For
+ example:
+
+ struct A { virtual void f(); char c1; };
+ struct B { B(); char c2; };
+ struct C : public A, public virtual B {};
+
+ In this case, G++ will not place `B' into the tail-padding for
+ `A'; other compilers will. You can avoid this problem by
+ explicitly padding `A' so that its size is a multiple of its
+ alignment (ignoring virtual base classes); that will cause
+ G++ and other compilers to layout `C' identically.
+
+
+`-Wctor-dtor-privacy (C++ only)'
+ Warn when a class seems unusable, because all the constructors or
+ destructors in a class are private and the class has no friends or
+ public static member functions.
+
+`-Wnon-virtual-dtor (C++ only)'
+ Warn when a class declares a non-virtual destructor that should
+ probably be virtual, because it looks like the class will be used
+ polymorphically.
+
+`-Wreorder (C++ only)'
+ Warn when the order of member initializers given in the code does
+ not match the order in which they must be executed. For instance:
+
+ struct A {
+ int i;
+ int j;
+ A(): j (0), i (1) { }
+ };
+
+ Here the compiler will warn that the member initializers for `i'
+ and `j' will be rearranged to match the declaration order of the
+ members.
+
+ The following `-W...' options are not affected by `-Wall'.
+
+`-Weffc++ (C++ only)'
+ Warn about violations of the following style guidelines from Scott
+ Meyers' `Effective C++' book:
+
+ * Item 11: Define a copy constructor and an assignment
+ operator for classes with dynamically allocated memory.
+
+ * Item 12: Prefer initialization to assignment in constructors.
+
+ * Item 14: Make destructors virtual in base classes.
+
+ * Item 15: Have `operator=' return a reference to `*this'.
+
+ * Item 23: Don't try to return a reference when you must
+ return an object.
+
+
+ and about violations of the following style guidelines from Scott
+ Meyers' `More Effective C++' book:
+
+ * Item 6: Distinguish between prefix and postfix forms of
+ increment and decrement operators.
+
+ * Item 7: Never overload `&&', `||', or `,'.
+
+
+ If you use this option, you should be aware that the standard
+ library headers do not obey all of these guidelines; you can use
+ `grep -v' to filter out those warnings.
+
+`-Wno-deprecated (C++ only)'
+ Do not warn about usage of deprecated features. *Note Deprecated
+ Features::.
+
+`-Wno-non-template-friend (C++ only)'
+ Disable warnings when non-templatized friend functions are declared
+ within a template. With the advent of explicit template
+ specification support in G++, if the name of the friend is an
+ unqualified-id (i.e., `friend foo(int)'), the C++ language
+ specification demands that the friend declare or define an
+ ordinary, nontemplate function. (Section 14.5.3). Before G++
+ implemented explicit specification, unqualified-ids could be
+ interpreted as a particular specialization of a templatized
+ function. Because this non-conforming behavior is no longer the
+ default behavior for G++, `-Wnon-template-friend' allows the
+ compiler to check existing code for potential trouble spots, and
+ is on by default. This new compiler behavior can be turned off
+ with `-Wno-non-template-friend' which keeps the conformant
+ compiler code but disables the helpful warning.
+
+`-Wold-style-cast (C++ only)'
+ Warn if an old-style (C-style) cast to a non-void type is used
+ within a C++ program. The new-style casts (`static_cast',
+ `reinterpret_cast', and `const_cast') are less vulnerable to
+ unintended effects, and much easier to grep for.
+
+`-Woverloaded-virtual (C++ only)'
+ Warn when a function declaration hides virtual functions from a
+ base class. For example, in:
+
+ struct A {
+ virtual void f();
+ };
+
+ struct B: public A {
+ void f(int);
+ };
+
+ the `A' class version of `f' is hidden in `B', and code like this:
+
+ B* b;
+ b->f();
+
+ will fail to compile.
+
+`-Wno-pmf-conversions (C++ only)'
+ Disable the diagnostic for converting a bound pointer to member
+ function to a plain pointer.
+
+`-Wsign-promo (C++ only)'
+ Warn when overload resolution chooses a promotion from unsigned or
+ enumeral type to a signed type over a conversion to an unsigned
+ type of the same size. Previous versions of G++ would try to
+ preserve unsignedness, but the standard mandates the current
+ behavior.
+
+`-Wsynth (C++ only)'
+ Warn when G++'s synthesis behavior does not match that of cfront.
+ For instance:
+
+ struct A {
+ operator int ();
+ A& operator = (int);
+ };
+
+ main ()
+ {
+ A a,b;
+ a = b;
+ }
+
+ In this example, G++ will synthesize a default `A& operator =
+ (const A&);', while cfront will use the user-defined `operator ='.
+
+\1f
+File: gcc.info, Node: Objective-C Dialect Options, Next: Language Independent Options, Prev: C++ Dialect Options, Up: Invoking GCC
+
+3.6 Options Controlling Objective-C Dialect
+===========================================
+
+This section describes the command-line options that are only meaningful
+for Objective-C programs; but you can also use most of the GNU compiler
+options regardless of what language your program is in. For example,
+you might compile a file `some_class.m' like this:
+
+ gcc -g -fgnu-runtime -O -c some_class.m
+
+In this example, only `-fgnu-runtime' is an option meant only for
+Objective-C programs; you can use the other options with any language
+supported by GCC.
+
+ Here is a list of options that are _only_ for compiling Objective-C
+programs:
+
+`-fconstant-string-class=CLASS-NAME'
+ Use CLASS-NAME as the name of the class to instantiate for each
+ literal string specified with the syntax `@"..."'. The default
+ class name is `NXConstantString'.
+
+`-fgnu-runtime'
+ Generate object code compatible with the standard GNU Objective-C
+ runtime. This is the default for most types of systems.
+
+`-fnext-runtime'
+ Generate output compatible with the NeXT runtime. This is the
+ default for NeXT-based systems, including Darwin and Mac OS X.
+
+`-gen-decls'
+ Dump interface declarations for all classes seen in the source
+ file to a file named `SOURCENAME.decl'.
+
+`-Wno-protocol'
+ Do not warn if methods required by a protocol are not implemented
+ in the class adopting it.
+
+`-Wselector'
+ Warn if a selector has multiple methods of different types defined.
+
+
+\1f
+File: gcc.info, Node: Language Independent Options, Next: Warning Options, Prev: Objective-C Dialect Options, Up: Invoking GCC
+
+3.7 Options to Control Diagnostic Messages Formatting
+=====================================================
+
+Traditionally, diagnostic messages have been formatted irrespective of
+the output device's aspect (e.g. its width, ...). The options described
+below can be used to control the diagnostic messages formatting
+algorithm, e.g. how many characters per line, how often source location
+information should be reported. Right now, only the C++ front end can
+honor these options. However it is expected, in the near future, that
+the remaining front ends would be able to digest them correctly.
+
+`-fmessage-length=N'
+ Try to format error messages so that they fit on lines of about N
+ characters. The default is 72 characters for `g++' and 0 for the
+ rest of the front ends supported by GCC. If N is zero, then no
+ line-wrapping will be done; each error message will appear on a
+ single line.
+
+`-fdiagnostics-show-location=once'
+ Only meaningful in line-wrapping mode. Instructs the diagnostic
+ messages reporter to emit _once_ source location information; that
+ is, in case the message is too long to fit on a single physical
+ line and has to be wrapped, the source location won't be emitted
+ (as prefix) again, over and over, in subsequent continuation
+ lines. This is the default behavior.
+
+`-fdiagnostics-show-location=every-line'
+ Only meaningful in line-wrapping mode. Instructs the diagnostic
+ messages reporter to emit the same source location information (as
+ prefix) for physical lines that result from the process of breaking
+ a message which is too long to fit on a single line.
+
+
+\1f
+File: gcc.info, Node: Warning Options, Next: Debugging Options, Prev: Language Independent Options, Up: Invoking GCC
+
+3.8 Options to Request or Suppress Warnings
+===========================================
+
+Warnings are diagnostic messages that report constructions which are
+not inherently erroneous but which are risky or suggest there may have
+been an error.
+
+ You can request many specific warnings with options beginning `-W',
+for example `-Wimplicit' to request warnings on implicit declarations.
+Each of these specific warning options also has a negative form
+beginning `-Wno-' to turn off warnings; for example, `-Wno-implicit'.
+This manual lists only one of the two forms, whichever is not the
+default.
+
+ The following options control the amount and kinds of warnings
+produced by GCC; for further, language-specific options also refer to
+*note C++ Dialect Options:: and *note Objective-C Dialect Options::.
+
+`-fsyntax-only'
+ Check the code for syntax errors, but don't do anything beyond
+ that.
+
+`-pedantic'
+ Issue all the warnings demanded by strict ISO C and ISO C++;
+ reject all programs that use forbidden extensions, and some other
+ programs that do not follow ISO C and ISO C++. For ISO C, follows
+ the version of the ISO C standard specified by any `-std' option
+ used.
+
+ Valid ISO C and ISO C++ programs should compile properly with or
+ without this option (though a rare few will require `-ansi' or a
+ `-std' option specifying the required version of ISO C). However,
+ without this option, certain GNU extensions and traditional C and
+ C++ features are supported as well. With this option, they are
+ rejected.
+
+ `-pedantic' does not cause warning messages for use of the
+ alternate keywords whose names begin and end with `__'. Pedantic
+ warnings are also disabled in the expression that follows
+ `__extension__'. However, only system header files should use
+ these escape routes; application programs should avoid them.
+ *Note Alternate Keywords::.
+
+ Some users try to use `-pedantic' to check programs for strict ISO
+ C conformance. They soon find that it does not do quite what they
+ want: it finds some non-ISO practices, but not all--only those for
+ which ISO C _requires_ a diagnostic, and some others for which
+ diagnostics have been added.
+
+ A feature to report any failure to conform to ISO C might be
+ useful in some instances, but would require considerable
+ additional work and would be quite different from `-pedantic'. We
+ don't have plans to support such a feature in the near future.
+
+ Where the standard specified with `-std' represents a GNU extended
+ dialect of C, such as `gnu89' or `gnu99', there is a corresponding
+ "base standard", the version of ISO C on which the GNU extended
+ dialect is based. Warnings from `-pedantic' are given where they
+ are required by the base standard. (It would not make sense for
+ such warnings to be given only for features not in the specified
+ GNU C dialect, since by definition the GNU dialects of C include
+ all features the compiler supports with the given option, and
+ there would be nothing to warn about.)
+
+`-pedantic-errors'
+ Like `-pedantic', except that errors are produced rather than
+ warnings.
+
+`-w'
+ Inhibit all warning messages.
+
+`-Wno-import'
+ Inhibit warning messages about the use of `#import'.
+
+`-Wchar-subscripts'
+ Warn if an array subscript has type `char'. This is a common cause
+ of error, as programmers often forget that this type is signed on
+ some machines.
+
+`-Wcomment'
+ Warn whenever a comment-start sequence `/*' appears in a `/*'
+ comment, or whenever a Backslash-Newline appears in a `//' comment.
+
+`-Wformat'
+ Check calls to `printf' and `scanf', etc., to make sure that the
+ arguments supplied have types appropriate to the format string
+ specified, and that the conversions specified in the format string
+ make sense. This includes standard functions, and others
+ specified by format attributes (*note Function Attributes::), in
+ the `printf', `scanf', `strftime' and `strfmon' (an X/Open
+ extension, not in the C standard) families.
+
+ The formats are checked against the format features supported by
+ GNU libc version 2.2. These include all ISO C89 and C99 features,
+ as well as features from the Single Unix Specification and some
+ BSD and GNU extensions. Other library implementations may not
+ support all these features; GCC does not support warning about
+ features that go beyond a particular library's limitations.
+ However, if `-pedantic' is used with `-Wformat', warnings will be
+ given about format features not in the selected standard version
+ (but not for `strfmon' formats, since those are not in any version
+ of the C standard). *Note Options Controlling C Dialect: C
+ Dialect Options.
+
+ `-Wformat' is included in `-Wall'. For more control over some
+ aspects of format checking, the options `-Wno-format-y2k',
+ `-Wno-format-extra-args', `-Wformat-nonliteral',
+ `-Wformat-security' and `-Wformat=2' are available, but are not
+ included in `-Wall'.
+
+`-Wno-format-y2k'
+ If `-Wformat' is specified, do not warn about `strftime' formats
+ which may yield only a two-digit year.
+
+`-Wno-format-extra-args'
+ If `-Wformat' is specified, do not warn about excess arguments to a
+ `printf' or `scanf' format function. The C standard specifies
+ that such arguments are ignored.
+
+ Where the unused arguments lie between used arguments that are
+ specified with `$' operand number specifications, normally
+ warnings are still given, since the implementation could not know
+ what type to pass to `va_arg' to skip the unused arguments.
+ However, in the case of `scanf' formats, this option will suppress
+ the warning if the unused arguments are all pointers, since the
+ Single Unix Specification says that such unused arguments are
+ allowed.
+
+`-Wformat-nonliteral'
+ If `-Wformat' is specified, also warn if the format string is not a
+ string literal and so cannot be checked, unless the format function
+ takes its format arguments as a `va_list'.
+
+`-Wformat-security'
+ If `-Wformat' is specified, also warn about uses of format
+ functions that represent possible security problems. At present,
+ this warns about calls to `printf' and `scanf' functions where the
+ format string is not a string literal and there are no format
+ arguments, as in `printf (foo);'. This may be a security hole if
+ the format string came from untrusted input and contains `%n'.
+ (This is currently a subset of what `-Wformat-nonliteral' warns
+ about, but in future warnings may be added to `-Wformat-security'
+ that are not included in `-Wformat-nonliteral'.)
+
+`-Wformat=2'
+ Enable `-Wformat' plus format checks not included in `-Wformat'.
+ Currently equivalent to `-Wformat -Wformat-nonliteral
+ -Wformat-security'.
+
+`-Wimplicit-int'
+ Warn when a declaration does not specify a type.
+
+`-Wimplicit-function-declaration'
+`-Werror-implicit-function-declaration'
+ Give a warning (or error) whenever a function is used before being
+ declared.
+
+`-Wimplicit'
+ Same as `-Wimplicit-int' and `-Wimplicit-function-declaration'.
+
+`-Wmain'
+ Warn if the type of `main' is suspicious. `main' should be a
+ function with external linkage, returning int, taking either zero
+ arguments, two, or three arguments of appropriate types.
+
+`-Wmissing-braces'
+ Warn if an aggregate or union initializer is not fully bracketed.
+ In the following example, the initializer for `a' is not fully
+ bracketed, but that for `b' is fully bracketed.
+
+ int a[2][2] = { 0, 1, 2, 3 };
+ int b[2][2] = { { 0, 1 }, { 2, 3 } };
+
+`-Wparentheses'
+ Warn if parentheses are omitted in certain contexts, such as when
+ there is an assignment in a context where a truth value is
+ expected, or when operators are nested whose precedence people
+ often get confused about.
+
+ Also warn about constructions where there may be confusion to which
+ `if' statement an `else' branch belongs. Here is an example of
+ such a case:
+
+ {
+ if (a)
+ if (b)
+ foo ();
+ else
+ bar ();
+ }
+
+ In C, every `else' branch belongs to the innermost possible `if'
+ statement, which in this example is `if (b)'. This is often not
+ what the programmer expected, as illustrated in the above example
+ by indentation the programmer chose. When there is the potential
+ for this confusion, GCC will issue a warning when this flag is
+ specified. To eliminate the warning, add explicit braces around
+ the innermost `if' statement so there is no way the `else' could
+ belong to the enclosing `if'. The resulting code would look like
+ this:
+
+ {
+ if (a)
+ {
+ if (b)
+ foo ();
+ else
+ bar ();
+ }
+ }
+
+`-Wsequence-point'
+ Warn about code that may have undefined semantics because of
+ violations of sequence point rules in the C standard.
+
+ The C standard defines the order in which expressions in a C
+ program are evaluated in terms of "sequence points", which
+ represent a partial ordering between the execution of parts of the
+ program: those executed before the sequence point, and those
+ executed after it. These occur after the evaluation of a full
+ expression (one which is not part of a larger expression), after
+ the evaluation of the first operand of a `&&', `||', `? :' or `,'
+ (comma) operator, before a function is called (but after the
+ evaluation of its arguments and the expression denoting the called
+ function), and in certain other places. Other than as expressed
+ by the sequence point rules, the order of evaluation of
+ subexpressions of an expression is not specified. All these rules
+ describe only a partial order rather than a total order, since,
+ for example, if two functions are called within one expression
+ with no sequence point between them, the order in which the
+ functions are called is not specified. However, the standards
+ committee have ruled that function calls do not overlap.
+
+ It is not specified when between sequence points modifications to
+ the values of objects take effect. Programs whose behavior
+ depends on this have undefined behavior; the C standard specifies
+ that "Between the previous and next sequence point an object shall
+ have its stored value modified at most once by the evaluation of
+ an expression. Furthermore, the prior value shall be read only to
+ determine the value to be stored.". If a program breaks these
+ rules, the results on any particular implementation are entirely
+ unpredictable.
+
+ Examples of code with undefined behavior are `a = a++;', `a[n] =
+ b[n++]' and `a[i++] = i;'. Some more complicated cases are not
+ diagnosed by this option, and it may give an occasional false
+ positive result, but in general it has been found fairly effective
+ at detecting this sort of problem in programs.
+
+ The present implementation of this option only works for C
+ programs. A future implementation may also work for C++ programs.
+
+ The C standard is worded confusingly, therefore there is some
+ debate over the precise meaning of the sequence point rules in
+ subtle cases. Links to discussions of the problem, including
+ proposed formal definitions, may be found on our readings page, at
+ `http://gcc.gnu.org/readings.html'.
+
+`-Wreturn-type'
+ Warn whenever a function is defined with a return-type that
+ defaults to `int'. Also warn about any `return' statement with no
+ return-value in a function whose return-type is not `void'.
+
+ For C++, a function without return type always produces a
+ diagnostic message, even when `-Wno-return-type' is specified.
+ The only exceptions are `main' and functions defined in system
+ headers.
+
+`-Wswitch'
+ Warn whenever a `switch' statement has an index of enumeral type
+ and lacks a `case' for one or more of the named codes of that
+ enumeration. (The presence of a `default' label prevents this
+ warning.) `case' labels outside the enumeration range also
+ provoke warnings when this option is used.
+
+`-Wtrigraphs'
+ Warn if any trigraphs are encountered that might change the
+ meaning of the program (trigraphs within comments are not warned
+ about).
+
+`-Wunused-function'
+ Warn whenever a static function is declared but not defined or a
+ non\-inline static function is unused.
+
+`-Wunused-label'
+ Warn whenever a label is declared but not used.
+
+ To suppress this warning use the `unused' attribute (*note
+ Variable Attributes::).
+
+`-Wunused-parameter'
+ Warn whenever a function parameter is unused aside from its
+ declaration.
+
+ To suppress this warning use the `unused' attribute (*note
+ Variable Attributes::).
+
+`-Wunused-variable'
+ Warn whenever a local variable or non-constant static variable is
+ unused aside from its declaration
+
+ To suppress this warning use the `unused' attribute (*note
+ Variable Attributes::).
+
+`-Wunused-value'
+ Warn whenever a statement computes a result that is explicitly not
+ used.
+
+ To suppress this warning cast the expression to `void'.
+
+`-Wunused'
+ All all the above `-Wunused' options combined.
+
+ In order to get a warning about an unused function parameter, you
+ must either specify `-W -Wunused' or separately specify
+ `-Wunused-parameter'.
+
+`-Wuninitialized'
+ Warn if an automatic variable is used without first being
+ initialized or if a variable may be clobbered by a `setjmp' call.
+
+ These warnings are possible only in optimizing compilation,
+ because they require data flow information that is computed only
+ when optimizing. If you don't specify `-O', you simply won't get
+ these warnings.
+
+ These warnings occur only for variables that are candidates for
+ register allocation. Therefore, they do not occur for a variable
+ that is declared `volatile', or whose address is taken, or whose
+ size is other than 1, 2, 4 or 8 bytes. Also, they do not occur for
+ structures, unions or arrays, even when they are in registers.
+
+ Note that there may be no warning about a variable that is used
+ only to compute a value that itself is never used, because such
+ computations may be deleted by data flow analysis before the
+ warnings are printed.
+
+ These warnings are made optional because GCC is not smart enough
+ to see all the reasons why the code might be correct despite
+ appearing to have an error. Here is one example of how this can
+ happen:
+
+ {
+ int x;
+ switch (y)
+ {
+ case 1: x = 1;
+ break;
+ case 2: x = 4;
+ break;
+ case 3: x = 5;
+ }
+ foo (x);
+ }
+
+ If the value of `y' is always 1, 2 or 3, then `x' is always
+ initialized, but GCC doesn't know this. Here is another common
+ case:
+
+ {
+ int save_y;
+ if (change_y) save_y = y, y = new_y;
+ ...
+ if (change_y) y = save_y;
+ }
+
+ This has no bug because `save_y' is used only if it is set.
+
+ This option also warns when a non-volatile automatic variable
+ might be changed by a call to `longjmp'. These warnings as well
+ are possible only in optimizing compilation.
+
+ The compiler sees only the calls to `setjmp'. It cannot know
+ where `longjmp' will be called; in fact, a signal handler could
+ call it at any point in the code. As a result, you may get a
+ warning even when there is in fact no problem because `longjmp'
+ cannot in fact be called at the place which would cause a problem.
+
+ Some spurious warnings can be avoided if you declare all the
+ functions you use that never return as `noreturn'. *Note Function
+ Attributes::.
+
+`-Wreorder (C++ only)'
+ Warn when the order of member initializers given in the code does
+ not match the order in which they must be executed. For instance:
+
+`-Wunknown-pragmas'
+ Warn when a #pragma directive is encountered which is not
+ understood by GCC. If this command line option is used, warnings
+ will even be issued for unknown pragmas in system header files.
+ This is not the case if the warnings were only enabled by the
+ `-Wall' command line option.
+
+`-Wall'
+ All of the above `-W' options combined. This enables all the
+ warnings about constructions that some users consider
+ questionable, and that are easy to avoid (or modify to prevent the
+ warning), even in conjunction with macros.
+
+`-Wdiv-by-zero'
+ Warn about compile-time integer division by zero. This is
+ default. To inhibit the warning messages, use `-Wno-div-by-zero'.
+ Floating point division by zero is not warned about, as it can be
+ a legitimate way of obtaining infinities and NaNs.
+
+`-Wmultichar'
+ Warn if a multicharacter constant (`'FOOF'') is used. This is
+ default. To inhibit the warning messages, use `-Wno-multichar'.
+ Usually they indicate a typo in the user's code, as they have
+ implementation-defined values, and should not be used in portable
+ code.
+
+`-Wsystem-headers'
+ Print warning messages for constructs found in system header files.
+ Warnings from system headers are normally suppressed, on the
+ assumption that they usually do not indicate real problems and
+ would only make the compiler output harder to read. Using this
+ command line option tells GCC to emit warnings from system headers
+ as if they occurred in user code. However, note that using
+ `-Wall' in conjunction with this option will _not_ warn about
+ unknown pragmas in system headers--for that, `-Wunknown-pragmas'
+ must also be used.
+
+ The following `-W...' options are not implied by `-Wall'. Some of
+them warn about constructions that users generally do not consider
+questionable, but which occasionally you might wish to check for;
+others warn about constructions that are necessary or hard to avoid in
+some cases, and there is no simple way to modify the code to suppress
+the warning.
+
+`-W'
+ Print extra warning messages for these events:
+
+ * A function can return either with or without a value.
+ (Falling off the end of the function body is considered
+ returning without a value.) For example, this function would
+ evoke such a warning:
+
+ foo (a)
+ {
+ if (a > 0)
+ return a;
+ }
+
+ * An expression-statement or the left-hand side of a comma
+ expression contains no side effects. To suppress the
+ warning, cast the unused expression to void. For example, an
+ expression such as `x[i,j]' will cause a warning, but
+ `x[(void)i,j]' will not.
+
+ * An unsigned value is compared against zero with `<' or `<='.
+
+ * A comparison like `x<=y<=z' appears; this is equivalent to
+ `(x<=y ? 1 : 0) <= z', which is a different interpretation
+ from that of ordinary mathematical notation.
+
+ * Storage-class specifiers like `static' are not the first
+ things in a declaration. According to the C Standard, this
+ usage is obsolescent.
+
+ * The return type of a function has a type qualifier such as
+ `const'. Such a type qualifier has no effect, since the
+ value returned by a function is not an lvalue. (But don't
+ warn about the GNU extension of `volatile void' return types.
+ That extension will be warned about if `-pedantic' is
+ specified.)
+
+ * If `-Wall' or `-Wunused' is also specified, warn about unused
+ arguments.
+
+ * A comparison between signed and unsigned values could produce
+ an incorrect result when the signed value is converted to
+ unsigned. (But don't warn if `-Wno-sign-compare' is also
+ specified.)
+
+ * An aggregate has a partly bracketed initializer. For
+ example, the following code would evoke such a warning,
+ because braces are missing around the initializer for `x.h':
+
+ struct s { int f, g; };
+ struct t { struct s h; int i; };
+ struct t x = { 1, 2, 3 };
+
+ * An aggregate has an initializer which does not initialize all
+ members. For example, the following code would cause such a
+ warning, because `x.h' would be implicitly initialized to
+ zero:
+
+ struct s { int f, g, h; };
+ struct s x = { 3, 4 };
+
+`-Wfloat-equal'
+ Warn if floating point values are used in equality comparisons.
+
+ The idea behind this is that sometimes it is convenient (for the
+ programmer) to consider floating-point values as approximations to
+ infinitely precise real numbers. If you are doing this, then you
+ need to compute (by analysing the code, or in some other way) the
+ maximum or likely maximum error that the computation introduces,
+ and allow for it when performing comparisons (and when producing
+ output, but that's a different problem). In particular, instead
+ of testing for equality, you would check to see whether the two
+ values have ranges that overlap; and this is done with the
+ relational operators, so equality comparisons are probably
+ mistaken.
+
+`-Wtraditional (C only)'
+ Warn about certain constructs that behave differently in
+ traditional and ISO C. Also warn about ISO C constructs that have
+ no traditional C equivalent, and/or problematic constructs which
+ should be avoided.
+
+ * Macro parameters that appear within string literals in the
+ macro body. In traditional C macro replacement takes place
+ within string literals, but does not in ISO C.
+
+ * In traditional C, some preprocessor directives did not exist.
+ Traditional preprocessors would only consider a line to be a
+ directive if the `#' appeared in column 1 on the line.
+ Therefore `-Wtraditional' warns about directives that
+ traditional C understands but would ignore because the `#'
+ does not appear as the first character on the line. It also
+ suggests you hide directives like `#pragma' not understood by
+ traditional C by indenting them. Some traditional
+ implementations would not recognize `#elif', so it suggests
+ avoiding it altogether.
+
+ * A function-like macro that appears without arguments.
+
+ * The unary plus operator.
+
+ * The `U' integer constant suffix, or the `F' or `L' floating
+ point constant suffixes. (Traditional C does support the `L'
+ suffix on integer constants.) Note, these suffixes appear in
+ macros defined in the system headers of most modern systems,
+ e.g. the `_MIN'/`_MAX' macros in `<limits.h>'. Use of these
+ macros in user code might normally lead to spurious warnings,
+ however gcc's integrated preprocessor has enough context to
+ avoid warning in these cases.
+
+ * A function declared external in one block and then used after
+ the end of the block.
+
+ * A `switch' statement has an operand of type `long'.
+
+ * A non-`static' function declaration follows a `static' one.
+ This construct is not accepted by some traditional C
+ compilers.
+
+ * The ISO type of an integer constant has a different width or
+ signedness from its traditional type. This warning is only
+ issued if the base of the constant is ten. I.e. hexadecimal
+ or octal values, which typically represent bit patterns, are
+ not warned about.
+
+ * Usage of ISO string concatenation is detected.
+
+ * Initialization of automatic aggregates.
+
+ * Identifier conflicts with labels. Traditional C lacks a
+ separate namespace for labels.
+
+ * Initialization of unions. If the initializer is zero, the
+ warning is omitted. This is done under the assumption that
+ the zero initializer in user code appears conditioned on e.g.
+ `__STDC__' to avoid missing initializer warnings and relies
+ on default initialization to zero in the traditional C case.
+
+ * Conversions by prototypes between fixed/floating point values
+ and vice versa. The absence of these prototypes when
+ compiling with traditional C would cause serious problems.
+ This is a subset of the possible conversion warnings, for the
+ full set use `-Wconversion'.
+
+`-Wundef'
+ Warn if an undefined identifier is evaluated in an `#if' directive.
+
+`-Wshadow'
+ Warn whenever a local variable shadows another local variable,
+ parameter or global variable or whenever a built-in function is
+ shadowed.
+
+`-Wlarger-than-LEN'
+ Warn whenever an object of larger than LEN bytes is defined.
+
+`-Wpointer-arith'
+ Warn about anything that depends on the "size of" a function type
+ or of `void'. GNU C assigns these types a size of 1, for
+ convenience in calculations with `void *' pointers and pointers to
+ functions.
+
+`-Wbad-function-cast (C only)'
+ Warn whenever a function call is cast to a non-matching type. For
+ example, warn if `int malloc()' is cast to `anything *'.
+
+`-Wcast-qual'
+ Warn whenever a pointer is cast so as to remove a type qualifier
+ from the target type. For example, warn if a `const char *' is
+ cast to an ordinary `char *'.
+
+`-Wcast-align'
+ Warn whenever a pointer is cast such that the required alignment
+ of the target is increased. For example, warn if a `char *' is
+ cast to an `int *' on machines where integers can only be accessed
+ at two- or four-byte boundaries.
+
+`-Wwrite-strings'
+ When compiling C, give string constants the type `const
+ char[LENGTH]' so that copying the address of one into a
+ non-`const' `char *' pointer will get a warning; when compiling
+ C++, warn about the deprecated conversion from string constants to
+ `char *'. These warnings will help you find at compile time code
+ that can try to write into a string constant, but only if you have
+ been very careful about using `const' in declarations and
+ prototypes. Otherwise, it will just be a nuisance; this is why we
+ did not make `-Wall' request these warnings.
+
+`-Wconversion'
+ Warn if a prototype causes a type conversion that is different
+ from what would happen to the same argument in the absence of a
+ prototype. This includes conversions of fixed point to floating
+ and vice versa, and conversions changing the width or signedness
+ of a fixed point argument except when the same as the default
+ promotion.
+
+ Also, warn if a negative integer constant expression is implicitly
+ converted to an unsigned type. For example, warn about the
+ assignment `x = -1' if `x' is unsigned. But do not warn about
+ explicit casts like `(unsigned) -1'.
+
+`-Wsign-compare'
+ Warn when a comparison between signed and unsigned values could
+ produce an incorrect result when the signed value is converted to
+ unsigned. This warning is also enabled by `-W'; to get the other
+ warnings of `-W' without this warning, use `-W -Wno-sign-compare'.
+
+`-Waggregate-return'
+ Warn if any functions that return structures or unions are defined
+ or called. (In languages where you can return an array, this also
+ elicits a warning.)
+
+`-Wstrict-prototypes (C only)'
+ Warn if a function is declared or defined without specifying the
+ argument types. (An old-style function definition is permitted
+ without a warning if preceded by a declaration which specifies the
+ argument types.)
+
+`-Wmissing-prototypes (C only)'
+ Warn if a global function is defined without a previous prototype
+ declaration. This warning is issued even if the definition itself
+ provides a prototype. The aim is to detect global functions that
+ fail to be declared in header files.
+
+`-Wmissing-declarations'
+ Warn if a global function is defined without a previous
+ declaration. Do so even if the definition itself provides a
+ prototype. Use this option to detect global functions that are
+ not declared in header files.
+
+`-Wmissing-noreturn'
+ Warn about functions which might be candidates for attribute
+ `noreturn'. Note these are only possible candidates, not absolute
+ ones. Care should be taken to manually verify functions actually
+ do not ever return before adding the `noreturn' attribute,
+ otherwise subtle code generation bugs could be introduced. You
+ will not get a warning for `main' in hosted C environments.
+
+`-Wmissing-format-attribute'
+ If `-Wformat' is enabled, also warn about functions which might be
+ candidates for `format' attributes. Note these are only possible
+ candidates, not absolute ones. GCC will guess that `format'
+ attributes might be appropriate for any function that calls a
+ function like `vprintf' or `vscanf', but this might not always be
+ the case, and some functions for which `format' attributes are
+ appropriate may not be detected. This option has no effect unless
+ `-Wformat' is enabled (possibly by `-Wall').
+
+`-Wno-deprecated-declarations'
+ Do not warn about uses of functions, variables, and types marked as
+ deprecated by using the `deprecated' attribute. (*note Function
+ Attributes::, *note Variable Attributes::, *note Type
+ Attributes::.)
+
+`-Wpacked'
+ Warn if a structure is given the packed attribute, but the packed
+ attribute has no effect on the layout or size of the structure.
+ Such structures may be mis-aligned for little benefit. For
+ instance, in this code, the variable `f.x' in `struct bar' will be
+ misaligned even though `struct bar' does not itself have the
+ packed attribute:
+
+ struct foo {
+ int x;
+ char a, b, c, d;
+ } __attribute__((packed));
+ struct bar {
+ char z;
+ struct foo f;
+ };
+
+`-Wpadded'
+ Warn if padding is included in a structure, either to align an
+ element of the structure or to align the whole structure.
+ Sometimes when this happens it is possible to rearrange the fields
+ of the structure to reduce the padding and so make the structure
+ smaller.
+
+`-Wredundant-decls'
+ Warn if anything is declared more than once in the same scope,
+ even in cases where multiple declaration is valid and changes
+ nothing.
+
+`-Wnested-externs (C only)'
+ Warn if an `extern' declaration is encountered within a function.
+
+`-Wunreachable-code'
+ Warn if the compiler detects that code will never be executed.
+
+ This option is intended to warn when the compiler detects that at
+ least a whole line of source code will never be executed, because
+ some condition is never satisfied or because it is after a
+ procedure that never returns.
+
+ It is possible for this option to produce a warning even though
+ there are circumstances under which part of the affected line can
+ be executed, so care should be taken when removing
+ apparently-unreachable code.
+
+ For instance, when a function is inlined, a warning may mean that
+ the line is unreachable in only one inlined copy of the function.
+
+ This option is not made part of `-Wall' because in a debugging
+ version of a program there is often substantial code which checks
+ correct functioning of the program and is, hopefully, unreachable
+ because the program does work. Another common use of unreachable
+ code is to provide behavior which is selectable at compile-time.
+
+`-Winline'
+ Warn if a function can not be inlined and it was declared as
+ inline.
+
+`-Wlong-long'
+ Warn if `long long' type is used. This is default. To inhibit
+ the warning messages, use `-Wno-long-long'. Flags `-Wlong-long'
+ and `-Wno-long-long' are taken into account only when `-pedantic'
+ flag is used.
+
+`-Wdisabled-optimization'
+ Warn if a requested optimization pass is disabled. This warning
+ does not generally indicate that there is anything wrong with your
+ code; it merely indicates that GCC's optimizers were unable to
+ handle the code effectively. Often, the problem is that your code
+ is too big or too complex; GCC will refuse to optimize programs
+ when the optimization itself is likely to take inordinate amounts
+ of time.
+
+`-Werror'
+ Make all warnings into errors.
+
+\1f
+File: gcc.info, Node: Debugging Options, Next: Optimize Options, Prev: Warning Options, Up: Invoking GCC
+
+3.9 Options for Debugging Your Program or GCC
+=============================================
+
+GCC has various special options that are used for debugging either your
+program or GCC:
+
+`-g'
+ Produce debugging information in the operating system's native
+ format (stabs, COFF, XCOFF, or DWARF). GDB can work with this
+ debugging information.
+
+ On most systems that use stabs format, `-g' enables use of extra
+ debugging information that only GDB can use; this extra information
+ makes debugging work better in GDB but will probably make other
+ debuggers crash or refuse to read the program. If you want to
+ control for certain whether to generate the extra information, use
+ `-gstabs+', `-gstabs', `-gxcoff+', `-gxcoff', `-gdwarf-1+',
+ `-gdwarf-1', or `-gvms' (see below).
+
+ Unlike most other C compilers, GCC allows you to use `-g' with
+ `-O'. The shortcuts taken by optimized code may occasionally
+ produce surprising results: some variables you declared may not
+ exist at all; flow of control may briefly move where you did not
+ expect it; some statements may not be executed because they
+ compute constant results or their values were already at hand;
+ some statements may execute in different places because they were
+ moved out of loops.
+
+ Nevertheless it proves possible to debug optimized output. This
+ makes it reasonable to use the optimizer for programs that might
+ have bugs.
+
+ The following options are useful when GCC is generated with the
+ capability for more than one debugging format.
+
+`-ggdb'
+ Produce debugging information for use by GDB. This means to use
+ the most expressive format available (DWARF 2, stabs, or the
+ native format if neither of those are supported), including GDB
+ extensions if at all possible.
+
+`-gstabs'
+ Produce debugging information in stabs format (if that is
+ supported), without GDB extensions. This is the format used by
+ DBX on most BSD systems. On MIPS, Alpha and System V Release 4
+ systems this option produces stabs debugging output which is not
+ understood by DBX or SDB. On System V Release 4 systems this
+ option requires the GNU assembler.
+
+`-gstabs+'
+ Produce debugging information in stabs format (if that is
+ supported), using GNU extensions understood only by the GNU
+ debugger (GDB). The use of these extensions is likely to make
+ other debuggers crash or refuse to read the program.
+
+`-gcoff'
+ Produce debugging information in COFF format (if that is
+ supported). This is the format used by SDB on most System V
+ systems prior to System V Release 4.
+
+`-gxcoff'
+ Produce debugging information in XCOFF format (if that is
+ supported). This is the format used by the DBX debugger on IBM
+ RS/6000 systems.
+
+`-gxcoff+'
+ Produce debugging information in XCOFF format (if that is
+ supported), using GNU extensions understood only by the GNU
+ debugger (GDB). The use of these extensions is likely to make
+ other debuggers crash or refuse to read the program, and may cause
+ assemblers other than the GNU assembler (GAS) to fail with an
+ error.
+
+`-gdwarf'
+ Produce debugging information in DWARF version 1 format (if that is
+ supported). This is the format used by SDB on most System V
+ Release 4 systems.
+
+`-gdwarf+'
+ Produce debugging information in DWARF version 1 format (if that is
+ supported), using GNU extensions understood only by the GNU
+ debugger (GDB). The use of these extensions is likely to make
+ other debuggers crash or refuse to read the program.
+
+`-gdwarf-2'
+ Produce debugging information in DWARF version 2 format (if that is
+ supported). This is the format used by DBX on IRIX 6.
+
+`-gvms'
+ Produce debugging information in VMS debug format (if that is
+ supported). This is the format used by DEBUG on VMS systems.
+
+`-gLEVEL'
+`-ggdbLEVEL'
+`-gstabsLEVEL'
+`-gcoffLEVEL'
+`-gxcoffLEVEL'
+`-gvmsLEVEL'
+ Request debugging information and also use LEVEL to specify how
+ much information. The default level is 2.
+
+ Level 1 produces minimal information, enough for making backtraces
+ in parts of the program that you don't plan to debug. This
+ includes descriptions of functions and external variables, but no
+ information about local variables and no line numbers.
+
+ Level 3 includes extra information, such as all the macro
+ definitions present in the program. Some debuggers support macro
+ expansion when you use `-g3'.
+
+ Note that in order to avoid confusion between DWARF1 debug level 2,
+ and DWARF2, neither `-gdwarf' nor `-gdwarf-2' accept a
+ concatenated debug level. Instead use an additional `-gLEVEL'
+ option to change the debug level for DWARF1 or DWARF2.
+
+`-p'
+ Generate extra code to write profile information suitable for the
+ analysis program `prof'. You must use this option when compiling
+ the source files you want data about, and you must also use it when
+ linking.
+
+`-pg'
+ Generate extra code to write profile information suitable for the
+ analysis program `gprof'. You must use this option when compiling
+ the source files you want data about, and you must also use it when
+ linking.
+
+`-Q'
+ Makes the compiler print out each function name as it is compiled,
+ and print some statistics about each pass when it finishes.
+
+`-ftime-report'
+ Makes the compiler print some statistics about the time consumed
+ by each pass when it finishes.
+
+`-fmem-report'
+ Makes the compiler print some statistics about permanent memory
+ allocation when it finishes.
+
+`-fprofile-arcs'
+ Instrument "arcs" during compilation to generate coverage data or
+ for profile-directed block ordering. During execution the program
+ records how many times each branch is executed and how many times
+ it is taken. When the compiled program exits it saves this data
+ to a file called `SOURCENAME.da' for each source file.
+
+ For profile-directed block ordering, compile the program with
+ `-fprofile-arcs' plus optimization and code generation options,
+ generate the arc profile information by running the program on a
+ selected workload, and then compile the program again with the same
+ optimization and code generation options plus
+ `-fbranch-probabilities' (*note Options that Control Optimization:
+ Optimize Options.).
+
+ The other use of `-fprofile-arcs' is for use with `gcov', when it
+ is used with the `-ftest-coverage' option.
+
+ With `-fprofile-arcs', for each function of your program GCC
+ creates a program flow graph, then finds a spanning tree for the
+ graph. Only arcs that are not on the spanning tree have to be
+ instrumented: the compiler adds code to count the number of times
+ that these arcs are executed. When an arc is the only exit or
+ only entrance to a block, the instrumentation code can be added to
+ the block; otherwise, a new basic block must be created to hold
+ the instrumentation code.
+
+`-ftest-coverage'
+ Create data files for the `gcov' code-coverage utility (*note
+ `gcov'--a Test Coverage Program: Gcov.). The data file names
+ begin with the name of your source file:
+
+ `SOURCENAME.bb'
+ A mapping from basic blocks to line numbers, which `gcov'
+ uses to associate basic block execution counts with line
+ numbers.
+
+ `SOURCENAME.bbg'
+ A list of all arcs in the program flow graph. This allows
+ `gcov' to reconstruct the program flow graph, so that it can
+ compute all basic block and arc execution counts from the
+ information in the `SOURCENAME.da' file.
+
+ Use `-ftest-coverage' with `-fprofile-arcs'; the latter option
+ adds instrumentation to the program, which then writes execution
+ counts to another data file:
+
+ `SOURCENAME.da'
+ Runtime arc execution counts, used in conjunction with the arc
+ information in the file `SOURCENAME.bbg'.
+
+ Coverage data will map better to the source files if
+ `-ftest-coverage' is used without optimization.
+
+`-dLETTERS'
+ Says to make debugging dumps during compilation at times specified
+ by LETTERS. This is used for debugging the compiler. The file
+ names for most of the dumps are made by appending a pass number
+ and a word to the source file name (e.g. `foo.c.00.rtl' or
+ `foo.c.01.sibling'). Here are the possible letters for use in
+ LETTERS, and their meanings:
+
+ `A'
+ Annotate the assembler output with miscellaneous debugging
+ information.
+
+ `b'
+ Dump after computing branch probabilities, to `FILE.14.bp'.
+
+ `B'
+ Dump after block reordering, to `FILE.29.bbro'.
+
+ `c'
+ Dump after instruction combination, to the file
+ `FILE.16.combine'.
+
+ `C'
+ Dump after the first if conversion, to the file `FILE.17.ce'.
+
+ `d'
+ Dump after delayed branch scheduling, to `FILE.31.dbr'.
+
+ `D'
+ Dump all macro definitions, at the end of preprocessing, in
+ addition to normal output.
+
+ `e'
+ Dump after SSA optimizations, to `FILE.04.ssa' and
+ `FILE.07.ussa'.
+
+ `E'
+ Dump after the second if conversion, to `FILE.26.ce2'.
+
+ `f'
+ Dump after life analysis, to `FILE.15.life'.
+
+ `F'
+ Dump after purging `ADDRESSOF' codes, to `FILE.09.addressof'.
+
+ `g'
+ Dump after global register allocation, to `FILE.21.greg'.
+
+ `h'
+ Dump after finalization of EH handling code, to `FILE.02.eh'.
+
+ `k'
+ Dump after reg-to-stack conversion, to `FILE.28.stack'.
+
+ `o'
+ Dump after post-reload optimizations, to `FILE.22.postreload'.
+
+ `G'
+ Dump after GCSE, to `FILE.10.gcse'.
+
+ `i'
+ Dump after sibling call optimizations, to `FILE.01.sibling'.
+
+ `j'
+ Dump after the first jump optimization, to `FILE.03.jump'.
+
+ `k'
+ Dump after conversion from registers to stack, to
+ `FILE.32.stack'.
+
+ `l'
+ Dump after local register allocation, to `FILE.20.lreg'.
+
+ `L'
+ Dump after loop optimization, to `FILE.11.loop'.
+
+ `M'
+ Dump after performing the machine dependent reorganisation
+ pass, to `FILE.30.mach'.
+
+ `n'
+ Dump after register renumbering, to `FILE.25.rnreg'.
+
+ `N'
+ Dump after the register move pass, to `FILE.18.regmove'.
+
+ `r'
+ Dump after RTL generation, to `FILE.00.rtl'.
+
+ `R'
+ Dump after the second scheduling pass, to `FILE.27.sched2'.
+
+ `s'
+ Dump after CSE (including the jump optimization that
+ sometimes follows CSE), to `FILE.08.cse'.
+
+ `S'
+ Dump after the first scheduling pass, to `FILE.19.sched'.
+
+ `t'
+ Dump after the second CSE pass (including the jump
+ optimization that sometimes follows CSE), to `FILE.12.cse2'.
+
+ `w'
+ Dump after the second flow pass, to `FILE.23.flow2'.
+
+ `X'
+ Dump after SSA dead code elimination, to `FILE.06.ssadce'.
+
+ `z'
+ Dump after the peephole pass, to `FILE.24.peephole2'.
+
+ `a'
+ Produce all the dumps listed above.
+
+ `m'
+ Print statistics on memory usage, at the end of the run, to
+ standard error.
+
+ `p'
+ Annotate the assembler output with a comment indicating which
+ pattern and alternative was used. The length of each
+ instruction is also printed.
+
+ `P'
+ Dump the RTL in the assembler output as a comment before each
+ instruction. Also turns on `-dp' annotation.
+
+ `v'
+ For each of the other indicated dump files (except for
+ `FILE.00.rtl'), dump a representation of the control flow
+ graph suitable for viewing with VCG to `FILE.PASS.vcg'.
+
+ `x'
+ Just generate RTL for a function instead of compiling it.
+ Usually used with `r'.
+
+ `y'
+ Dump debugging information during parsing, to standard error.
+
+`-fdump-unnumbered'
+ When doing debugging dumps (see `-d' option above), suppress
+ instruction numbers and line number note output. This makes it
+ more feasible to use diff on debugging dumps for compiler
+ invocations with different options, in particular with and without
+ `-g'.
+
+`-fdump-translation-unit (C and C++ only)'
+`-fdump-translation-unit-OPTIONS (C and C++ only)'
+ Dump a representation of the tree structure for the entire
+ translation unit to a file. The file name is made by appending
+ `.tu' to the source file name. If the `-OPTIONS' form is used,
+ OPTIONS controls the details of the dump as described for the
+ `-fdump-tree' options.
+
+`-fdump-class-hierarchy (C++ only)'
+`-fdump-class-hierarchy-OPTIONS (C++ only)'
+ Dump a representation of each class's hierarchy and virtual
+ function table layout to a file. The file name is made by
+ appending `.class' to the source file name. If the `-OPTIONS'
+ form is used, OPTIONS controls the details of the dump as
+ described for the `-fdump-tree' options.
+
+`-fdump-tree-SWITCH (C++ only)'
+`-fdump-tree-SWITCH-OPTIONS (C++ only)'
+ Control the dumping at various stages of processing the
+ intermediate language tree to a file. The file name is generated
+ by appending a switch specific suffix to the source file name. If
+ the `-OPTIONS' form is used, OPTIONS is a list of `-' separated
+ options that control the details of the dump. Not all options are
+ applicable to all dumps, those which are not meaningful will be
+ ignored. The following options are available
+
+ `address'
+ Print the address of each node. Usually this is not
+ meaningful as it changes according to the environment and
+ source file. Its primary use is for tying up a dump file with
+ a debug environment.
+
+ `slim'
+ Inhibit dumping of members of a scope or body of a function
+ merely because that scope has been reached. Only dump such
+ items when they are directly reachable by some other path.
+
+ `all'
+ Turn on all options.
+
+ The following tree dumps are possible:
+ `original'
+ Dump before any tree based optimization, to `FILE.original'.
+
+ `optimized'
+ Dump after all tree based optimization, to `FILE.optimized'.
+
+ `inlined'
+ Dump after function inlining, to `FILE.inlined'.
+
+`-fsched-verbose=N'
+ On targets that use instruction scheduling, this option controls
+ the amount of debugging output the scheduler prints. This
+ information is written to standard error, unless `-dS' or `-dR' is
+ specified, in which case it is output to the usual dump listing
+ file, `.sched' or `.sched2' respectively. However for N greater
+ than nine, the output is always printed to standard error.
+
+ For N greater than zero, `-fsched-verbose' outputs the same
+ information as `-dRS'. For N greater than one, it also output
+ basic block probabilities, detailed ready list information and
+ unit/insn info. For N greater than two, it includes RTL at abort
+ point, control-flow and regions info. And for N over four,
+ `-fsched-verbose' also includes dependence info.
+
+`-fpretend-float'
+ When running a cross-compiler, pretend that the target machine
+ uses the same floating point format as the host machine. This
+ causes incorrect output of the actual floating constants, but the
+ actual instruction sequence will probably be the same as GCC would
+ make when running on the target machine.
+
+`-save-temps'
+ Store the usual "temporary" intermediate files permanently; place
+ them in the current directory and name them based on the source
+ file. Thus, compiling `foo.c' with `-c -save-temps' would produce
+ files `foo.i' and `foo.s', as well as `foo.o'. This creates a
+ preprocessed `foo.i' output file even though the compiler now
+ normally uses an integrated preprocessor.
+
+`-time'
+ Report the CPU time taken by each subprocess in the compilation
+ sequence. For C source files, this is the compiler proper and
+ assembler (plus the linker if linking is done). The output looks
+ like this:
+
+ # cc1 0.12 0.01
+ # as 0.00 0.01
+
+ The first number on each line is the "user time," that is time
+ spent executing the program itself. The second number is "system
+ time," time spent executing operating system routines on behalf of
+ the program. Both numbers are in seconds.
+
+`-print-file-name=LIBRARY'
+ Print the full absolute name of the library file LIBRARY that
+ would be used when linking--and don't do anything else. With this
+ option, GCC does not compile or link anything; it just prints the
+ file name.
+
+`-print-multi-directory'
+ Print the directory name corresponding to the multilib selected by
+ any other switches present in the command line. This directory is
+ supposed to exist in `GCC_EXEC_PREFIX'.
+
+`-print-multi-lib'
+ Print the mapping from multilib directory names to compiler
+ switches that enable them. The directory name is separated from
+ the switches by `;', and each switch starts with an `@' instead of
+ the `-', without spaces between multiple switches. This is
+ supposed to ease shell-processing.
+
+`-print-prog-name=PROGRAM'
+ Like `-print-file-name', but searches for a program such as `cpp'.
+
+`-print-libgcc-file-name'
+ Same as `-print-file-name=libgcc.a'.
+
+ This is useful when you use `-nostdlib' or `-nodefaultlibs' but
+ you do want to link with `libgcc.a'. You can do
+
+ gcc -nostdlib FILES... `gcc -print-libgcc-file-name`
+
+`-print-search-dirs'
+ Print the name of the configured installation directory and a list
+ of program and library directories gcc will search--and don't do
+ anything else.
+
+ This is useful when gcc prints the error message `installation
+ problem, cannot exec cpp0: No such file or directory'. To resolve
+ this you either need to put `cpp0' and the other compiler
+ components where gcc expects to find them, or you can set the
+ environment variable `GCC_EXEC_PREFIX' to the directory where you
+ installed them. Don't forget the trailing '/'. *Note Environment
+ Variables::.
+
+`-dumpmachine'
+ Print the compiler's target machine (for example,
+ `i686-pc-linux-gnu')--and don't do anything else.
+
+`-dumpversion'
+ Print the compiler version (for example, `3.0')--and don't do
+ anything else.
+
+`-dumpspecs'
+ Print the compiler's built-in specs--and don't do anything else.
+ (This is used when GCC itself is being built.) *Note Spec Files::.
+
+\1f
+File: gcc.info, Node: Optimize Options, Next: Preprocessor Options, Prev: Debugging Options, Up: Invoking GCC
+
+3.10 Options That Control Optimization
+======================================
+
+These options control various sorts of optimizations:
+
+`-O'
+`-O1'
+ Optimize. Optimizing compilation takes somewhat more time, and a
+ lot more memory for a large function.
+
+ Without `-O', the compiler's goal is to reduce the cost of
+ compilation and to make debugging produce the expected results.
+ Statements are independent: if you stop the program with a
+ breakpoint between statements, you can then assign a new value to
+ any variable or change the program counter to any other statement
+ in the function and get exactly the results you would expect from
+ the source code.
+
+ With `-O', the compiler tries to reduce code size and execution
+ time, without performing any optimizations that take a great deal
+ of compilation time.
+
+`-O2'
+ Optimize even more. GCC performs nearly all supported
+ optimizations that do not involve a space-speed tradeoff. The
+ compiler does not perform loop unrolling or function inlining when
+ you specify `-O2'. As compared to `-O', this option increases
+ both compilation time and the performance of the generated code.
+
+ `-O2' turns on all optional optimizations except for loop
+ unrolling, function inlining, and register renaming. It also
+ turns on the `-fforce-mem' option on all machines and frame
+ pointer elimination on machines where doing so does not interfere
+ with debugging.
+
+ Please note the warning under `-fgcse' about invoking `-O2' on
+ programs that use computed gotos.
+
+`-O3'
+ Optimize yet more. `-O3' turns on all optimizations specified by
+ `-O2' and also turns on the `-finline-functions' and
+ `-frename-registers' options.
+
+`-O0'
+ Do not optimize.
+
+`-Os'
+ Optimize for size. `-Os' enables all `-O2' optimizations that do
+ not typically increase code size. It also performs further
+ optimizations designed to reduce code size.
+
+ If you use multiple `-O' options, with or without level numbers,
+ the last such option is the one that is effective.
+
+ Options of the form `-fFLAG' specify machine-independent flags.
+Most flags have both positive and negative forms; the negative form of
+`-ffoo' would be `-fno-foo'. In the table below, only one of the forms
+is listed--the one which is not the default. You can figure out the
+other form by either removing `no-' or adding it.
+
+`-ffloat-store'
+ Do not store floating point variables in registers, and inhibit
+ other options that might change whether a floating point value is
+ taken from a register or memory.
+
+ This option prevents undesirable excess precision on machines such
+ as the 68000 where the floating registers (of the 68881) keep more
+ precision than a `double' is supposed to have. Similarly for the
+ x86 architecture. For most programs, the excess precision does
+ only good, but a few programs rely on the precise definition of
+ IEEE floating point. Use `-ffloat-store' for such programs, after
+ modifying them to store all pertinent intermediate computations
+ into variables.
+
+`-fno-default-inline'
+ Do not make member functions inline by default merely because they
+ are defined inside the class scope (C++ only). Otherwise, when
+ you specify `-O', member functions defined inside class scope are
+ compiled inline by default; i.e., you don't need to add `inline'
+ in front of the member function name.
+
+`-fno-defer-pop'
+ Always pop the arguments to each function call as soon as that
+ function returns. For machines which must pop arguments after a
+ function call, the compiler normally lets arguments accumulate on
+ the stack for several function calls and pops them all at once.
+
+`-fforce-mem'
+ Force memory operands to be copied into registers before doing
+ arithmetic on them. This produces better code by making all memory
+ references potential common subexpressions. When they are not
+ common subexpressions, instruction combination should eliminate
+ the separate register-load. The `-O2' option turns on this option.
+
+`-fforce-addr'
+ Force memory address constants to be copied into registers before
+ doing arithmetic on them. This may produce better code just as
+ `-fforce-mem' may.
+
+`-fomit-frame-pointer'
+ Don't keep the frame pointer in a register for functions that
+ don't need one. This avoids the instructions to save, set up and
+ restore frame pointers; it also makes an extra register available
+ in many functions. *It also makes debugging impossible on some
+ machines.*
+
+ On some machines, such as the VAX, this flag has no effect, because
+ the standard calling sequence automatically handles the frame
+ pointer and nothing is saved by pretending it doesn't exist. The
+ machine-description macro `FRAME_POINTER_REQUIRED' controls
+ whether a target machine supports this flag. *Note Register
+ Usage: (gccint)Registers.
+
+`-foptimize-sibling-calls'
+ Optimize sibling and tail recursive calls.
+
+`-ftrapv'
+ This option generates traps for signed overflow on addition,
+ subtraction, multiplication operations.
+
+`-fno-inline'
+ Don't pay attention to the `inline' keyword. Normally this option
+ is used to keep the compiler from expanding any functions inline.
+ Note that if you are not optimizing, no functions can be expanded
+ inline.
+
+`-finline-functions'
+ Integrate all simple functions into their callers. The compiler
+ heuristically decides which functions are simple enough to be worth
+ integrating in this way.
+
+ If all calls to a given function are integrated, and the function
+ is declared `static', then the function is normally not output as
+ assembler code in its own right.
+
+`-finline-limit=N'
+ By default, gcc limits the size of functions that can be inlined.
+ This flag allows the control of this limit for functions that are
+ explicitly marked as inline (ie marked with the inline keyword or
+ defined within the class definition in c++). N is the size of
+ functions that can be inlined in number of pseudo instructions
+ (not counting parameter handling). The default value of N is 600.
+ Increasing this value can result in more inlined code at the cost
+ of compilation time and memory consumption. Decreasing usually
+ makes the compilation faster and less code will be inlined (which
+ presumably means slower programs). This option is particularly
+ useful for programs that use inlining heavily such as those based
+ on recursive templates with C++.
+
+ _Note:_ pseudo instruction represents, in this particular context,
+ an abstract measurement of function's size. In no way, it
+ represents a count of assembly instructions and as such its exact
+ meaning might change from one release to an another.
+
+`-fkeep-inline-functions'
+ Even if all calls to a given function are integrated, and the
+ function is declared `static', nevertheless output a separate
+ run-time callable version of the function. This switch does not
+ affect `extern inline' functions.
+
+`-fkeep-static-consts'
+ Emit variables declared `static const' when optimization isn't
+ turned on, even if the variables aren't referenced.
+
+ GCC enables this option by default. If you want to force the
+ compiler to check if the variable was referenced, regardless of
+ whether or not optimization is turned on, use the
+ `-fno-keep-static-consts' option.
+
+`-fmerge-constants'
+ Attempt to merge identical constants (string constants and
+ floating point constants) accross compilation units.
+
+ This option is default for optimized compilation if assembler and
+ linker support it. Use `-fno-merge-constants' to inhibit this
+ behavior.
+
+`-fmerge-all-constants'
+ Attempt to merge identical constants and identical variables.
+
+ This option implies `-fmerge-constants'. In addition to
+ `-fmerge-constants' this considers e.g. even constant initialized
+ arrays or initialized constant variables with integral or floating
+ point types. Languages like C or C++ require each non-automatic
+ variable to have distinct location, so using this option will
+ result in non-conforming behavior.
+
+`-fno-branch-count-reg'
+ Do not use "decrement and branch" instructions on a count register,
+ but instead generate a sequence of instructions that decrement a
+ register, compare it against zero, then branch based upon the
+ result. This option is only meaningful on architectures that
+ support such instructions, which include x86, PowerPC, IA-64 and
+ S/390.
+
+`-fno-function-cse'
+ Do not put function addresses in registers; make each instruction
+ that calls a constant function contain the function's address
+ explicitly.
+
+ This option results in less efficient code, but some strange hacks
+ that alter the assembler output may be confused by the
+ optimizations performed when this option is not used.
+
+`-ffast-math'
+ Sets `-fno-math-errno', `-funsafe-math-optimizations', and
+ `-fno-trapping-math'.
+
+ This option causes the preprocessor macro `__FAST_MATH__' to be
+ defined.
+
+ This option should never be turned on by any `-O' option since it
+ can result in incorrect output for programs which depend on an
+ exact implementation of IEEE or ISO rules/specifications for math
+ functions.
+
+`-fno-math-errno'
+ Do not set ERRNO after calling math functions that are executed
+ with a single instruction, e.g., sqrt. A program that relies on
+ IEEE exceptions for math error handling may want to use this flag
+ for speed while maintaining IEEE arithmetic compatibility.
+
+ This option should never be turned on by any `-O' option since it
+ can result in incorrect output for programs which depend on an
+ exact implementation of IEEE or ISO rules/specifications for math
+ functions.
+
+ The default is `-fmath-errno'.
+
+`-funsafe-math-optimizations'
+ Allow optimizations for floating-point arithmetic that (a) assume
+ that arguments and results are valid and (b) may violate IEEE or
+ ANSI standards. When used at link-time, it may include libraries
+ or startup files that change the default FPU control word or other
+ similar optimizations.
+
+ This option should never be turned on by any `-O' option since it
+ can result in incorrect output for programs which depend on an
+ exact implementation of IEEE or ISO rules/specifications for math
+ functions.
+
+ The default is `-fno-unsafe-math-optimizations'.
+
+`-fno-trapping-math'
+ Compile code assuming that floating-point operations cannot
+ generate user-visible traps. Setting this option may allow faster
+ code if one relies on "non-stop" IEEE arithmetic, for example.
+
+ This option should never be turned on by any `-O' option since it
+ can result in incorrect output for programs which depend on an
+ exact implementation of IEEE or ISO rules/specifications for math
+ functions.
+
+ The default is `-ftrapping-math'.
+
+`-fbounds-check'
+ For front-ends that support it, generate additional code to check
+ that indices used to access arrays are within the declared range.
+ This is currenly only supported by the Java and Fortran 77
+ front-ends, where this option defaults to true and false
+ respectively.
+
+
+ The following options control specific optimizations. The `-O2'
+option turns on all of these optimizations except `-funroll-loops' and
+`-funroll-all-loops'. On most machines, the `-O' option turns on the
+`-fthread-jumps' and `-fdelayed-branch' options, but specific machines
+may handle it differently.
+
+ You can use the following flags in the rare cases when "fine-tuning"
+of optimizations to be performed is desired.
+
+ Not all of the optimizations performed by GCC have `-f' options to
+control them.
+
+`-fstrength-reduce'
+ Perform the optimizations of loop strength reduction and
+ elimination of iteration variables.
+
+`-fthread-jumps'
+ Perform optimizations where we check to see if a jump branches to a
+ location where another comparison subsumed by the first is found.
+ If so, the first branch is redirected to either the destination of
+ the second branch or a point immediately following it, depending
+ on whether the condition is known to be true or false.
+
+`-fcse-follow-jumps'
+ In common subexpression elimination, scan through jump instructions
+ when the target of the jump is not reached by any other path. For
+ example, when CSE encounters an `if' statement with an `else'
+ clause, CSE will follow the jump when the condition tested is
+ false.
+
+`-fcse-skip-blocks'
+ This is similar to `-fcse-follow-jumps', but causes CSE to follow
+ jumps which conditionally skip over blocks. When CSE encounters a
+ simple `if' statement with no else clause, `-fcse-skip-blocks'
+ causes CSE to follow the jump around the body of the `if'.
+
+`-frerun-cse-after-loop'
+ Re-run common subexpression elimination after loop optimizations
+ has been performed.
+
+`-frerun-loop-opt'
+ Run the loop optimizer twice.
+
+`-fgcse'
+ Perform a global common subexpression elimination pass. This pass
+ also performs global constant and copy propagation.
+
+ _Note:_ When compiling a program using computed gotos, a GCC
+ extension, you may get better runtime performance if you disable
+ the global common subexpression elmination pass by adding
+ `-fno-gcse' to the command line.
+
+`-fgcse-lm'
+ When `-fgcse-lm' is enabled, global common subexpression
+ elimination will attempt to move loads which are only killed by
+ stores into themselves. This allows a loop containing a
+ load/store sequence to be changed to a load outside the loop, and
+ a copy/store within the loop.
+
+`-fgcse-sm'
+ When `-fgcse-sm' is enabled, A store motion pass is run after
+ global common subexpression elimination. This pass will attempt
+ to move stores out of loops. When used in conjunction with
+ `-fgcse-lm', loops containing a load/store sequence can be changed
+ to a load before the loop and a store after the loop.
+
+`-fdelete-null-pointer-checks'
+ Use global dataflow analysis to identify and eliminate useless
+ checks for null pointers. The compiler assumes that dereferencing
+ a null pointer would have halted the program. If a pointer is
+ checked after it has already been dereferenced, it cannot be null.
+
+ In some environments, this assumption is not true, and programs can
+ safely dereference null pointers. Use
+ `-fno-delete-null-pointer-checks' to disable this optimization for
+ programs which depend on that behavior.
+
+`-fexpensive-optimizations'
+ Perform a number of minor optimizations that are relatively
+ expensive.
+
+`-foptimize-register-move'
+`-fregmove'
+ Attempt to reassign register numbers in move instructions and as
+ operands of other simple instructions in order to maximize the
+ amount of register tying. This is especially helpful on machines
+ with two-operand instructions. GCC enables this optimization by
+ default with `-O2' or higher.
+
+ Note `-fregmove' and `-foptimize-register-move' are the same
+ optimization.
+
+`-fdelayed-branch'
+ If supported for the target machine, attempt to reorder
+ instructions to exploit instruction slots available after delayed
+ branch instructions.
+
+`-fschedule-insns'
+ If supported for the target machine, attempt to reorder
+ instructions to eliminate execution stalls due to required data
+ being unavailable. This helps machines that have slow floating
+ point or memory load instructions by allowing other instructions
+ to be issued until the result of the load or floating point
+ instruction is required.
+
+`-fschedule-insns2'
+ Similar to `-fschedule-insns', but requests an additional pass of
+ instruction scheduling after register allocation has been done.
+ This is especially useful on machines with a relatively small
+ number of registers and where memory load instructions take more
+ than one cycle.
+
+`-fno-sched-interblock'
+ Don't schedule instructions across basic blocks. This is normally
+ enabled by default when scheduling before register allocation, i.e.
+ with `-fschedule-insns' or at `-O2' or higher.
+
+`-fno-sched-spec'
+ Don't allow speculative motion of non-load instructions. This is
+ normally enabled by default when scheduling before register
+ allocation, i.e. with `-fschedule-insns' or at `-O2' or higher.
+
+`-fsched-spec-load'
+ Allow speculative motion of some load instructions. This only
+ makes sense when scheduling before register allocation, i.e. with
+ `-fschedule-insns' or at `-O2' or higher.
+
+`-fsched-spec-load-dangerous'
+ Allow speculative motion of more load instructions. This only
+ makes sense when scheduling before register allocation, i.e. with
+ `-fschedule-insns' or at `-O2' or higher.
+
+`-ffunction-sections'
+`-fdata-sections'
+ Place each function or data item into its own section in the output
+ file if the target supports arbitrary sections. The name of the
+ function or the name of the data item determines the section's name
+ in the output file.
+
+ Use these options on systems where the linker can perform
+ optimizations to improve locality of reference in the instruction
+ space. HPPA processors running HP-UX and Sparc processors running
+ Solaris 2 have linkers with such optimizations. Other systems
+ using the ELF object format as well as AIX may have these
+ optimizations in the future.
+
+ Only use these options when there are significant benefits from
+ doing so. When you specify these options, the assembler and
+ linker will create larger object and executable files and will
+ also be slower. You will not be able to use `gprof' on all
+ systems if you specify this option and you may have problems with
+ debugging if you specify both this option and `-g'.
+
+`-fcaller-saves'
+ Enable values to be allocated in registers that will be clobbered
+ by function calls, by emitting extra instructions to save and
+ restore the registers around such calls. Such allocation is done
+ only when it seems to result in better code than would otherwise
+ be produced.
+
+ This option is always enabled by default on certain machines,
+ usually those which have no call-preserved registers to use
+ instead.
+
+ For all machines, optimization level 2 and higher enables this
+ flag by default.
+
+`-funroll-loops'
+ Unroll loops whose number of iterations can be determined at
+ compile time or upon entry to the loop. `-funroll-loops' implies
+ both `-fstrength-reduce' and `-frerun-cse-after-loop'. This
+ option makes code larger, and may or may not make it run faster.
+
+`-funroll-all-loops'
+ Unroll all loops, even if their number of iterations is uncertain
+ when the loop is entered. This usually makes programs run more
+ slowly. `-funroll-all-loops' implies the same options as
+ `-funroll-loops',
+
+`-fprefetch-loop-arrays'
+ If supported by the target machine, generate instructions to
+ prefetch memory to improve the performance of loops that access
+ large arrays.
+
+`-fmove-all-movables'
+ Forces all invariant computations in loops to be moved outside the
+ loop.
+
+`-freduce-all-givs'
+ Forces all general-induction variables in loops to be
+ strength-reduced.
+
+ _Note:_ When compiling programs written in Fortran,
+ `-fmove-all-movables' and `-freduce-all-givs' are enabled by
+ default when you use the optimizer.
+
+ These options may generate better or worse code; results are highly
+ dependent on the structure of loops within the source code.
+
+ These two options are intended to be removed someday, once they
+ have helped determine the efficacy of various approaches to
+ improving loop optimizations.
+
+ Please let us (<gcc@gcc.gnu.org> and <fortran@gnu.org>) know how
+ use of these options affects the performance of your production
+ code. We're very interested in code that runs _slower_ when these
+ options are _enabled_.
+
+`-fno-peephole'
+`-fno-peephole2'
+ Disable any machine-specific peephole optimizations. The
+ difference between `-fno-peephole' and `-fno-peephole2' is in how
+ they are implemented in the compiler; some targets use one, some
+ use the other, a few use both.
+
+`-fbranch-probabilities'
+ After running a program compiled with `-fprofile-arcs' (*note
+ Options for Debugging Your Program or `gcc': Debugging Options.),
+ you can compile it a second time using `-fbranch-probabilities',
+ to improve optimizations based on the number of times each branch
+ was taken. When the program compiled with `-fprofile-arcs' exits
+ it saves arc execution counts to a file called `SOURCENAME.da' for
+ each source file The information in this data file is very
+ dependent on the structure of the generated code, so you must use
+ the same source code and the same optimization options for both
+ compilations.
+
+ With `-fbranch-probabilities', GCC puts a `REG_EXEC_COUNT' note on
+ the first instruction of each basic block, and a `REG_BR_PROB'
+ note on each `JUMP_INSN' and `CALL_INSN'. These can be used to
+ improve optimization. Currently, they are only used in one place:
+ in `reorg.c', instead of guessing which path a branch is mostly to
+ take, the `REG_BR_PROB' values are used to exactly determine which
+ path is taken more often.
+
+`-fno-guess-branch-probability'
+ Do not guess branch probabilities using a randomized model.
+
+ Sometimes gcc will opt to use a randomized model to guess branch
+ probabilities, when none are available from either profiling
+ feedback (`-fprofile-arcs') or `__builtin_expect'. This means that
+ different runs of the compiler on the same program may produce
+ different object code.
+
+ In a hard real-time system, people don't want different runs of the
+ compiler to produce code that has different behavior; minimizing
+ non-determinism is of paramount import. This switch allows users
+ to reduce non-determinism, possibly at the expense of inferior
+ optimization.
+
+`-fstrict-aliasing'
+ Allows the compiler to assume the strictest aliasing rules
+ applicable to the language being compiled. For C (and C++), this
+ activates optimizations based on the type of expressions. In
+ particular, an object of one type is assumed never to reside at
+ the same address as an object of a different type, unless the
+ types are almost the same. For example, an `unsigned int' can
+ alias an `int', but not a `void*' or a `double'. A character type
+ may alias any other type.
+
+ Pay special attention to code like this:
+ union a_union {
+ int i;
+ double d;
+ };
+
+ int f() {
+ a_union t;
+ t.d = 3.0;
+ return t.i;
+ }
+ The practice of reading from a different union member than the one
+ most recently written to (called "type-punning") is common. Even
+ with `-fstrict-aliasing', type-punning is allowed, provided the
+ memory is accessed through the union type. So, the code above
+ will work as expected. However, this code might not:
+ int f() {
+ a_union t;
+ int* ip;
+ t.d = 3.0;
+ ip = &t.i;
+ return *ip;
+ }
+
+ Every language that wishes to perform language-specific alias
+ analysis should define a function that computes, given an `tree'
+ node, an alias set for the node. Nodes in different alias sets
+ are not allowed to alias. For an example, see the C front-end
+ function `c_get_alias_set'.
+
+`-falign-functions'
+`-falign-functions=N'
+ Align the start of functions to the next power-of-two greater than
+ N, skipping up to N bytes. For instance, `-falign-functions=32'
+ aligns functions to the next 32-byte boundary, but
+ `-falign-functions=24' would align to the next 32-byte boundary
+ only if this can be done by skipping 23 bytes or less.
+
+ `-fno-align-functions' and `-falign-functions=1' are equivalent
+ and mean that functions will not be aligned.
+
+ Some assemblers only support this flag when N is a power of two;
+ in that case, it is rounded up.
+
+ If N is not specified, use a machine-dependent default.
+
+`-falign-labels'
+`-falign-labels=N'
+ Align all branch targets to a power-of-two boundary, skipping up to
+ N bytes like `-falign-functions'. This option can easily make
+ code slower, because it must insert dummy operations for when the
+ branch target is reached in the usual flow of the code.
+
+ If `-falign-loops' or `-falign-jumps' are applicable and are
+ greater than this value, then their values are used instead.
+
+ If N is not specified, use a machine-dependent default which is
+ very likely to be `1', meaning no alignment.
+
+`-falign-loops'
+`-falign-loops=N'
+ Align loops to a power-of-two boundary, skipping up to N bytes
+ like `-falign-functions'. The hope is that the loop will be
+ executed many times, which will make up for any execution of the
+ dummy operations.
+
+ If N is not specified, use a machine-dependent default.
+
+`-falign-jumps'
+`-falign-jumps=N'
+ Align branch targets to a power-of-two boundary, for branch targets
+ where the targets can only be reached by jumping, skipping up to N
+ bytes like `-falign-functions'. In this case, no dummy operations
+ need be executed.
+
+ If N is not specified, use a machine-dependent default.
+
+`-fssa'
+ Perform optimizations in static single assignment form. Each
+ function's flow graph is translated into SSA form, optimizations
+ are performed, and the flow graph is translated back from SSA
+ form. Users should not specify this option, since it is not yet
+ ready for production use.
+
+`-fssa-ccp'
+ Perform Sparse Conditional Constant Propagation in SSA form.
+ Requires `-fssa'. Like `-fssa', this is an experimental feature.
+
+`-fssa-dce'
+ Perform aggressive dead-code elimination in SSA form. Requires
+ `-fssa'. Like `-fssa', this is an experimental feature.
+
+`-fsingle-precision-constant'
+ Treat floating point constant as single precision constant instead
+ of implicitly converting it to double precision constant.
+
+`-frename-registers'
+ Attempt to avoid false dependencies in scheduled code by making use
+ of registers left over after register allocation. This
+ optimization will most benefit processors with lots of registers.
+ It can, however, make debugging impossible, since variables will
+ no longer stay in a "home register".
+
+`-fno-cprop-registers'
+ After register allocation and post-register allocation instruction
+ splitting, we perform a copy-propagation pass to try to reduce
+ scheduling dependencies and occasionally eliminate the copy.
+
+`--param NAME=VALUE'
+ In some places, GCC uses various constants to control the amount of
+ optimization that is done. For example, GCC will not inline
+ functions that contain more that a certain number of instructions.
+ You can control some of these constants on the command-line using
+ the `--param' option.
+
+ In each case, the VALUE is an integer. The allowable choices for
+ NAME are given in the following table:
+
+ `max-delay-slot-insn-search'
+ The maximum number of instructions to consider when looking
+ for an instruction to fill a delay slot. If more than this
+ arbitrary number of instructions is searched, the time
+ savings from filling the delay slot will be minimal so stop
+ searching. Increasing values mean more aggressive
+ optimization, making the compile time increase with probably
+ small improvement in executable run time.
+
+ `max-delay-slot-live-search'
+ When trying to fill delay slots, the maximum number of
+ instructions to consider when searching for a block with
+ valid live register information. Increasing this arbitrarily
+ chosen value means more aggressive optimization, increasing
+ the compile time. This parameter should be removed when the
+ delay slot code is rewritten to maintain the control-flow
+ graph.
+
+ `max-gcse-memory'
+ The approximate maximum amount of memory that will be
+ allocated in order to perform the global common subexpression
+ elimination optimization. If more memory than specified is
+ required, the optimization will not be done.
+
+ `max-gcse-passes'
+ The maximum number of passes of GCSE to run.
+
+ `max-pending-list-length'
+ The maximum number of pending dependencies scheduling will
+ allow before flushing the current state and starting over.
+ Large functions with few branches or calls can create
+ excessively large lists which needlessly consume memory and
+ resources.
+
+ `max-inline-insns'
+ If an function contains more than this many instructions, it
+ will not be inlined. This option is precisely equivalent to
+ `-finline-limit'.
+
+
+\1f
+File: gcc.info, Node: Preprocessor Options, Next: Assembler Options, Prev: Optimize Options, Up: Invoking GCC
+
+3.11 Options Controlling the Preprocessor
+=========================================
+
+These options control the C preprocessor, which is run on each C source
+file before actual compilation.
+
+ If you use the `-E' option, nothing is done except preprocessing.
+Some of these options make sense only together with `-E' because they
+cause the preprocessor output to be unsuitable for actual compilation.
+
+ You can use `-Wp,OPTION' to bypass the compiler driver and pass
+OPTION directly through to the preprocessor. If OPTION contains
+commas, it is split into multiple options at the commas. However, many
+options are modified, translated or interpreted by the compiler driver
+before being passed to the preprocessor, and `-Wp' forcibly bypasses
+this phase. The preprocessor's direct interface is undocumented and
+subject to change, so whenever possible you should avoid using `-Wp'
+and let the driver handle the options instead.
+
+`-D NAME'
+ Predefine NAME as a macro, with definition `1'.
+
+`-D NAME=DEFINITION'
+ Predefine NAME as a macro, with definition DEFINITION. There are
+ no restrictions on the contents of DEFINITION, but if you are
+ invoking the preprocessor from a shell or shell-like program you
+ may need to use the shell's quoting syntax to protect characters
+ such as spaces that have a meaning in the shell syntax.
+
+ If you wish to define a function-like macro on the command line,
+ write its argument list with surrounding parentheses before the
+ equals sign (if any). Parentheses are meaningful to most shells,
+ so you will need to quote the option. With `sh' and `csh',
+ `-D'NAME(ARGS...)=DEFINITION'' works.
+
+ `-D' and `-U' options are processed in the order they are given on
+ the command line. All `-imacros FILE' and `-include FILE' options
+ are processed after all `-D' and `-U' options.
+
+`-U NAME'
+ Cancel any previous definition of NAME, either built in or
+ provided with a `-D' option.
+
+`-undef'
+ Do not predefine any system-specific macros. The common predefined
+ macros remain defined.
+
+`-I DIR'
+ Add the directory DIR to the list of directories to be searched
+ for header files. Directories named by `-I' are searched before
+ the standard system include directories.
+
+ It is dangerous to specify a standard system include directory in
+ an `-I' option. This defeats the special treatment of system
+ headers . It can also defeat the repairs to buggy system headers
+ which GCC makes when it is installed.
+
+`-o FILE'
+ Write output to FILE. This is the same as specifying FILE as the
+ second non-option argument to `cpp'. `gcc' has a different
+ interpretation of a second non-option argument, so you must use
+ `-o' to specify the output file.
+
+`-Wall'
+ Turns on all optional warnings which are desirable for normal
+ code. At present this is `-Wcomment' and `-Wtrigraphs'. Note that
+ many of the preprocessor's warnings are on by default and have no
+ options to control them.
+
+`-Wcomment'
+`-Wcomments'
+ Warn whenever a comment-start sequence `/*' appears in a `/*'
+ comment, or whenever a backslash-newline appears in a `//' comment.
+ (Both forms have the same effect.)
+
+`-Wtrigraphs'
+ Warn if any trigraphs are encountered. This option used to take
+ effect only if `-trigraphs' was also specified, but now works
+ independently. Warnings are not given for trigraphs within
+ comments, as they do not affect the meaning of the program.
+
+`-Wtraditional'
+ Warn about certain constructs that behave differently in
+ traditional and ISO C. Also warn about ISO C constructs that have
+ no traditional C equivalent, and problematic constructs which
+ should be avoided.
+
+`-Wimport'
+ Warn the first time `#import' is used.
+
+`-Wundef'
+ Warn whenever an identifier which is not a macro is encountered in
+ an `#if' directive, outside of `defined'. Such identifiers are
+ replaced with zero.
+
+`-Werror'
+ Make all warnings into hard errors. Source code which triggers
+ warnings will be rejected.
+
+`-Wsystem-headers'
+ Issue warnings for code in system headers. These are normally
+ unhelpful in finding bugs in your own code, therefore suppressed.
+ If you are responsible for the system library, you may want to see
+ them.
+
+`-w'
+ Suppress all warnings, including those which GNU CPP issues by
+ default.
+
+`-pedantic'
+ Issue all the mandatory diagnostics listed in the C standard.
+ Some of them are left out by default, since they trigger
+ frequently on harmless code.
+
+`-pedantic-errors'
+ Issue all the mandatory diagnostics, and make all mandatory
+ diagnostics into errors. This includes mandatory diagnostics that
+ GCC issues without `-pedantic' but treats as warnings.
+
+`-M'
+ Instead of outputting the result of preprocessing, output a rule
+ suitable for `make' describing the dependencies of the main source
+ file. The preprocessor outputs one `make' rule containing the
+ object file name for that source file, a colon, and the names of
+ all the included files, including those coming from `-include' or
+ `-imacros' command line options.
+
+ Unless specified explicitly (with `-MT' or `-MQ'), the object file
+ name consists of the basename of the source file with any suffix
+ replaced with object file suffix. If there are many included
+ files then the rule is split into several lines using `\'-newline.
+ The rule has no commands.
+
+ This option does not suppress the preprocessor's debug output,
+ such as `-dM'. To avoid mixing such debug output with the
+ dependency rules you should explicitly specify the dependency
+ output file with `-MF', or use an environment variable like
+ `DEPENDENCIES_OUTPUT' (*note DEPENDENCIES_OUTPUT::). Debug output
+ will still be sent to the regular output stream as normal.
+
+ Passing `-M' to the driver implies `-E'.
+
+`-MM'
+ Like `-M' but do not mention header files that are found in system
+ header directories, nor header files that are included, directly
+ or indirectly, from such a header.
+
+ This implies that the choice of angle brackets or double quotes in
+ an `#include' directive does not in itself determine whether that
+ header will appear in `-MM' dependency output. This is a slight
+ change in semantics from GCC versions 3.0 and earlier.
+
+`-MF FILE'
+ When used with `-M' or `-MM', specifies a file to write the
+ dependencies to. If no `-MF' switch is given the preprocessor
+ sends the rules to the same place it would have sent preprocessed
+ output.
+
+ When used with the driver options `-MD' or `-MMD', `-MF' overrides
+ the default dependency output file.
+
+`-MG'
+ When used with `-M' or `-MM', `-MG' says to treat missing header
+ files as generated files and assume they live in the same
+ directory as the source file. It suppresses preprocessed output,
+ as a missing header file is ordinarily an error.
+
+ This feature is used in automatic updating of makefiles.
+
+`-MP'
+ This option instructs CPP to add a phony target for each dependency
+ other than the main file, causing each to depend on nothing. These
+ dummy rules work around errors `make' gives if you remove header
+ files without updating the `Makefile' to match.
+
+ This is typical output:
+
+ test.o: test.c test.h
+
+ test.h:
+
+`-MT TARGET'
+ Change the target of the rule emitted by dependency generation. By
+ default CPP takes the name of the main input file, including any
+ path, deletes any file suffix such as `.c', and appends the
+ platform's usual object suffix. The result is the target.
+
+ An `-MT' option will set the target to be exactly the string you
+ specify. If you want multiple targets, you can specify them as a
+ single argument to `-MT', or use multiple `-MT' options.
+
+ For example, `-MT '$(objpfx)foo.o'' might give
+
+ $(objpfx)foo.o: foo.c
+
+`-MQ TARGET'
+ Same as `-MT', but it quotes any characters which are special to
+ Make. `-MQ '$(objpfx)foo.o'' gives
+
+ $$(objpfx)foo.o: foo.c
+
+ The default target is automatically quoted, as if it were given
+ with `-MQ'.
+
+`-MD'
+ `-MD' is equivalent to `-M -MF FILE', except that `-E' is not
+ implied. The driver determines FILE based on whether an `-o'
+ option is given. If it is, the driver uses its argument but with
+ a suffix of `.d', otherwise it take the basename of the input file
+ and applies a `.d' suffix.
+
+ If `-MD' is used in conjunction with `-E', any `-o' switch is
+ understood to specify the dependency output file (but *note
+ -MF::), but if used without `-E', each `-o' is understood to
+ specify a target object file.
+
+ Since `-E' is not implied, `-MD' can be used to generate a
+ dependency output file as a side-effect of the compilation process.
+
+`-MMD'
+ Like `-MD' except mention only user header files, not system
+ -header files.
+
+`-x c'
+`-x c++'
+`-x objective-c'
+`-x assembler-with-cpp'
+ Specify the source language: C, C++, Objective-C, or assembly.
+ This has nothing to do with standards conformance or extensions;
+ it merely selects which base syntax to expect. If you give none
+ of these options, cpp will deduce the language from the extension
+ of the source file: `.c', `.cc', `.m', or `.S'. Some other common
+ extensions for C++ and assembly are also recognized. If cpp does
+ not recognize the extension, it will treat the file as C; this is
+ the most generic mode.
+
+ *Note_* Previous versions of cpp accepted a `-lang' option which
+ selected both the language and the standards conformance level.
+ This option has been removed, because it conflicts with the `-l'
+ option.
+
+`-std=STANDARD'
+`-ansi'
+ Specify the standard to which the code should conform. Currently
+ cpp only knows about the standards for C; other language standards
+ will be added in the future.
+
+ STANDARD may be one of:
+ `iso9899:1990'
+ `c89'
+ The ISO C standard from 1990. `c89' is the customary
+ shorthand for this version of the standard.
+
+ The `-ansi' option is equivalent to `-std=c89'.
+
+ `iso9899:199409'
+ The 1990 C standard, as amended in 1994.
+
+ `iso9899:1999'
+ `c99'
+ `iso9899:199x'
+ `c9x'
+ The revised ISO C standard, published in December 1999.
+ Before publication, this was known as C9X.
+
+ `gnu89'
+ The 1990 C standard plus GNU extensions. This is the default.
+
+ `gnu99'
+ `gnu9x'
+ The 1999 C standard plus GNU extensions.
+
+`-I-'
+ Split the include path. Any directories specified with `-I'
+ options before `-I-' are searched only for headers requested with
+ `#include "FILE"'; they are not searched for `#include <FILE>'.
+ If additional directories are specified with `-I' options after
+ the `-I-', those directories are searched for all `#include'
+ directives.
+
+ In addition, `-I-' inhibits the use of the directory of the current
+ file directory as the first search directory for `#include "FILE"'.
+
+`-nostdinc'
+ Do not search the standard system directories for header files.
+ Only the directories you have specified with `-I' options (and the
+ directory of the current file, if appropriate) are searched.
+
+`-nostdinc++'
+ Do not search for header files in the C++-specific standard
+ directories, but do still search the other standard directories.
+ (This option is used when building the C++ library.)
+
+`-include FILE'
+ Process FILE as if `#include "file"' appeared as the first line of
+ the primary source file. However, the first directory searched
+ for FILE is the preprocessor's working directory _instead of_ the
+ directory containing the main source file. If not found there, it
+ is searched for in the remainder of the `#include "..."' search
+ chain as normal.
+
+ If multiple `-include' options are given, the files are included
+ in the order they appear on the command line.
+
+`-imacros FILE'
+ Exactly like `-include', except that any output produced by
+ scanning FILE is thrown away. Macros it defines remain defined.
+ This allows you to acquire all the macros from a header without
+ also processing its declarations.
+
+ All files specified by `-imacros' are processed before all files
+ specified by `-include'.
+
+`-idirafter DIR'
+ Search DIR for header files, but do it _after_ all directories
+ specified with `-I' and the standard system directories have been
+ exhausted. DIR is treated as a system include directory.
+
+`-iprefix PREFIX'
+ Specify PREFIX as the prefix for subsequent `-iwithprefix'
+ options. If the prefix represents a directory, you should include
+ the final `/'.
+
+`-iwithprefix DIR'
+`-iwithprefixbefore DIR'
+ Append DIR to the prefix specified previously with `-iprefix', and
+ add the resulting directory to the include search path.
+ `-iwithprefixbefore' puts it in the same place `-I' would;
+ `-iwithprefix' puts it where `-idirafter' would.
+
+ Use of these options is discouraged.
+
+`-isystem DIR'
+ Search DIR for header files, after all directories specified by
+ `-I' but before the standard system directories. Mark it as a
+ system directory, so that it gets the same special treatment as is
+ applied to the standard system directories.
+
+`-fpreprocessed'
+ Indicate to the preprocessor that the input file has already been
+ preprocessed. This suppresses things like macro expansion,
+ trigraph conversion, escaped newline splicing, and processing of
+ most directives. The preprocessor still recognizes and removes
+ comments, so that you can pass a file preprocessed with `-C' to
+ the compiler without problems. In this mode the integrated
+ preprocessor is little more than a tokenizer for the front ends.
+
+ `-fpreprocessed' is implicit if the input file has one of the
+ extensions `.i', `.ii' or `.mi'. These are the extensions that
+ GCC uses for preprocessed files created by `-save-temps'.
+
+`-ftabstop=WIDTH'
+ Set the distance between tab stops. This helps the preprocessor
+ report correct column numbers in warnings or errors, even if tabs
+ appear on the line. If the value is less than 1 or greater than
+ 100, the option is ignored. The default is 8.
+
+`-fno-show-column'
+ Do not print column numbers in diagnostics. This may be necessary
+ if diagnostics are being scanned by a program that does not
+ understand the column numbers, such as `dejagnu'.
+
+`-A PREDICATE=ANSWER'
+ Make an assertion with the predicate PREDICATE and answer ANSWER.
+ This form is preferred to the older form `-A PREDICATE(ANSWER)',
+ which is still supported, because it does not use shell special
+ characters.
+
+`-A -PREDICATE=ANSWER'
+ Cancel an assertion with the predicate PREDICATE and answer ANSWER.
+
+`-A-'
+ Cancel all predefined assertions and all assertions preceding it on
+ the command line. Also, undefine all predefined macros and all
+ macros preceding it on the command line. (This is a historical
+ wart and may change in the future.)
+
+`-dCHARS'
+ CHARS is a sequence of one or more of the following characters,
+ and must not be preceded by a space. Other characters are
+ interpreted by the compiler proper, or reserved for future
+ versions of GCC, and so are silently ignored. If you specify
+ characters whose behavior conflicts, the result is undefined.
+
+ `M'
+ Instead of the normal output, generate a list of `#define'
+ directives for all the macros defined during the execution of
+ the preprocessor, including predefined macros. This gives
+ you a way of finding out what is predefined in your version
+ of the preprocessor. Assuming you have no file `foo.h', the
+ command
+
+ touch foo.h; cpp -dM foo.h
+
+ will show all the predefined macros.
+
+ `D'
+ Like `M' except in two respects: it does _not_ include the
+ predefined macros, and it outputs _both_ the `#define'
+ directives and the result of preprocessing. Both kinds of
+ output go to the standard output file.
+
+ `N'
+ Like `D', but emit only the macro names, not their expansions.
+
+ `I'
+ Output `#include' directives in addition to the result of
+ preprocessing.
+
+`-P'
+ Inhibit generation of linemarkers in the output from the
+ preprocessor. This might be useful when running the preprocessor
+ on something that is not C code, and will be sent to a program
+ which might be confused by the linemarkers.
+
+`-C'
+ Do not discard comments. All comments are passed through to the
+ output file, except for comments in processed directives, which
+ are deleted along with the directive.
+
+ You should be prepared for side effects when using `-C'; it causes
+ the preprocessor to treat comments as tokens in their own right.
+ For example, comments appearing at the start of what would be a
+ directive line have the effect of turning that line into an
+ ordinary source line, since the first token on the line is no
+ longer a `#'.
+
+`-gcc'
+ Define the macros __GNUC__, __GNUC_MINOR__ and
+ __GNUC_PATCHLEVEL__. These are defined automatically when you use
+ `gcc -E'; you can turn them off in that case with `-no-gcc'.
+
+`-traditional'
+ Try to imitate the behavior of old-fashioned C, as opposed to ISO
+ C.
+
+`-trigraphs'
+ Process trigraph sequences. These are three-character sequences,
+ all starting with `??', that are defined by ISO C to stand for
+ single characters. For example, `??/' stands for `\', so `'??/n''
+ is a character constant for a newline. By default, GCC ignores
+ trigraphs, but in standard-conforming modes it converts them. See
+ the `-std' and `-ansi' options.
+
+ The nine trigraphs and their replacements are
+
+ Trigraph: ??( ??) ??< ??> ??= ??/ ??' ??! ??-
+ Replacement: [ ] { } # \ ^ | ~
+
+`-remap'
+ Enable special code to work around file systems which only permit
+ very short file names, such as MS-DOS.
+
+`-$'
+ Forbid the use of `$' in identifiers. The C standard allows
+ implementations to define extra characters that can appear in
+ identifiers. By default GNU CPP permits `$', a common extension.
+
+`-h'
+`--help'
+`--target-help'
+ Print text describing all the command line options instead of
+ preprocessing anything.
+
+`-v'
+ Verbose mode. Print out GNU CPP's version number at the beginning
+ of execution, and report the final form of the include path.
+
+`-H'
+ Print the name of each header file used, in addition to other
+ normal activities. Each name is indented to show how deep in the
+ `#include' stack it is.
+
+`-version'
+`--version'
+ Print out GNU CPP's version number. With one dash, proceed to
+ preprocess as normal. With two dashes, exit immediately.
+
+\1f
+File: gcc.info, Node: Assembler Options, Next: Link Options, Prev: Preprocessor Options, Up: Invoking GCC
+
+3.12 Passing Options to the Assembler
+=====================================
+
+You can pass options to the assembler.
+
+`-Wa,OPTION'
+ Pass OPTION as an option to the assembler. If OPTION contains
+ commas, it is split into multiple options at the commas.
+
+\1f
+File: gcc.info, Node: Link Options, Next: Directory Options, Prev: Assembler Options, Up: Invoking GCC
+
+3.13 Options for Linking
+========================
+
+These options come into play when the compiler links object files into
+an executable output file. They are meaningless if the compiler is not
+doing a link step.
+
+`OBJECT-FILE-NAME'
+ A file name that does not end in a special recognized suffix is
+ considered to name an object file or library. (Object files are
+ distinguished from libraries by the linker according to the file
+ contents.) If linking is done, these object files are used as
+ input to the linker.
+
+`-c'
+`-S'
+`-E'
+ If any of these options is used, then the linker is not run, and
+ object file names should not be used as arguments. *Note Overall
+ Options::.
+
+`-lLIBRARY'
+`-l LIBRARY'
+ Search the library named LIBRARY when linking. (The second
+ alternative with the library as a separate argument is only for
+ POSIX compliance and is not recommended.)
+
+ It makes a difference where in the command you write this option;
+ the linker searches and processes libraries and object files in
+ the order they are specified. Thus, `foo.o -lz bar.o' searches
+ library `z' after file `foo.o' but before `bar.o'. If `bar.o'
+ refers to functions in `z', those functions may not be loaded.
+
+ The linker searches a standard list of directories for the library,
+ which is actually a file named `libLIBRARY.a'. The linker then
+ uses this file as if it had been specified precisely by name.
+
+ The directories searched include several standard system
+ directories plus any that you specify with `-L'.
+
+ Normally the files found this way are library files--archive files
+ whose members are object files. The linker handles an archive
+ file by scanning through it for members which define symbols that
+ have so far been referenced but not defined. But if the file that
+ is found is an ordinary object file, it is linked in the usual
+ fashion. The only difference between using an `-l' option and
+ specifying a file name is that `-l' surrounds LIBRARY with `lib'
+ and `.a' and searches several directories.
+
+`-lobjc'
+ You need this special case of the `-l' option in order to link an
+ Objective-C program.
+
+`-nostartfiles'
+ Do not use the standard system startup files when linking. The
+ standard system libraries are used normally, unless `-nostdlib' or
+ `-nodefaultlibs' is used.
+
+`-nodefaultlibs'
+ Do not use the standard system libraries when linking. Only the
+ libraries you specify will be passed to the linker. The standard
+ startup files are used normally, unless `-nostartfiles' is used.
+ The compiler may generate calls to memcmp, memset, and memcpy for
+ System V (and ISO C) environments or to bcopy and bzero for BSD
+ environments. These entries are usually resolved by entries in
+ libc. These entry points should be supplied through some other
+ mechanism when this option is specified.
+
+`-nostdlib'
+ Do not use the standard system startup files or libraries when
+ linking. No startup files and only the libraries you specify will
+ be passed to the linker. The compiler may generate calls to
+ memcmp, memset, and memcpy for System V (and ISO C) environments
+ or to bcopy and bzero for BSD environments. These entries are
+ usually resolved by entries in libc. These entry points should be
+ supplied through some other mechanism when this option is
+ specified.
+
+ One of the standard libraries bypassed by `-nostdlib' and
+ `-nodefaultlibs' is `libgcc.a', a library of internal subroutines
+ that GCC uses to overcome shortcomings of particular machines, or
+ special needs for some languages. (*Note Interfacing to GCC
+ Output: (gccint)Interface, for more discussion of `libgcc.a'.) In
+ most cases, you need `libgcc.a' even when you want to avoid other
+ standard libraries. In other words, when you specify `-nostdlib'
+ or `-nodefaultlibs' you should usually specify `-lgcc' as well.
+ This ensures that you have no unresolved references to internal GCC
+ library subroutines. (For example, `__main', used to ensure C++
+ constructors will be called; *note `collect2': (gccint)Collect2.)
+
+`-s'
+ Remove all symbol table and relocation information from the
+ executable.
+
+`-static'
+ On systems that support dynamic linking, this prevents linking
+ with the shared libraries. On other systems, this option has no
+ effect.
+
+`-shared'
+ Produce a shared object which can then be linked with other
+ objects to form an executable. Not all systems support this
+ option. For predictable results, you must also specify the same
+ set of options that were used to generate code (`-fpic', `-fPIC',
+ or model suboptions) when you specify this option.(1)
+
+`-shared-libgcc'
+`-static-libgcc'
+ On systems that provide `libgcc' as a shared library, these options
+ force the use of either the shared or static version respectively.
+ If no shared version of `libgcc' was built when the compiler was
+ configured, these options have no effect.
+
+ There are several situations in which an application should use the
+ shared `libgcc' instead of the static version. The most common of
+ these is when the application wishes to throw and catch exceptions
+ across different shared libraries. In that case, each of the
+ libraries as well as the application itself should use the shared
+ `libgcc'.
+
+ Therefore, the G++ and GCJ drivers automatically add
+ `-shared-libgcc' whenever you build a shared library or a main
+ executable, because C++ and Java programs typically use
+ exceptions, so this is the right thing to do.
+
+ If, instead, you use the GCC driver to create shared libraries,
+ you may find that they will not always be linked with the shared
+ `libgcc'. If GCC finds, at its configuration time, that you have
+ a GNU linker that does not support option `--eh-frame-hdr', it
+ will link the shared version of `libgcc' into shared libraries by
+ default. Otherwise, it will take advantage of the linker and
+ optimize away the linking with the shared version of `libgcc',
+ linking with the static version of libgcc by default. This allows
+ exceptions to propagate through such shared libraries, without
+ incurring relocation costs at library load time.
+
+ However, if a library or main executable is supposed to throw or
+ catch exceptions, you must link it using the G++ or GCJ driver, as
+ appropriate for the languages used in the program, or using the
+ option `-shared-libgcc', such that it is linked with the shared
+ `libgcc'.
+
+`-symbolic'
+ Bind references to global symbols when building a shared object.
+ Warn about any unresolved references (unless overridden by the
+ link editor option `-Xlinker -z -Xlinker defs'). Only a few
+ systems support this option.
+
+`-Xlinker OPTION'
+ Pass OPTION as an option to the linker. You can use this to
+ supply system-specific linker options which GCC does not know how
+ to recognize.
+
+ If you want to pass an option that takes an argument, you must use
+ `-Xlinker' twice, once for the option and once for the argument.
+ For example, to pass `-assert definitions', you must write
+ `-Xlinker -assert -Xlinker definitions'. It does not work to write
+ `-Xlinker "-assert definitions"', because this passes the entire
+ string as a single argument, which is not what the linker expects.
+
+`-Wl,OPTION'
+ Pass OPTION as an option to the linker. If OPTION contains
+ commas, it is split into multiple options at the commas.
+
+`-u SYMBOL'
+ Pretend the symbol SYMBOL is undefined, to force linking of
+ library modules to define it. You can use `-u' multiple times with
+ different symbols to force loading of additional library modules.
+
+ ---------- Footnotes ----------
+
+ (1) On some systems, `gcc -shared' needs to build supplementary stub
+code for constructors to work. On multi-libbed systems, `gcc -shared'
+must select the correct support libraries to link against. Failing to
+supply the correct flags may lead to subtle defects. Supplying them in
+cases where they are not necessary is innocuous.
+
+\1f
+File: gcc.info, Node: Directory Options, Next: Spec Files, Prev: Link Options, Up: Invoking GCC
+
+3.14 Options for Directory Search
+=================================
+
+These options specify directories to search for header files, for
+libraries and for parts of the compiler:
+
+`-IDIR'
+ Add the directory DIR to the head of the list of directories to be
+ searched for header files. This can be used to override a system
+ header file, substituting your own version, since these
+ directories are searched before the system header file
+ directories. However, you should not use this option to add
+ directories that contain vendor-supplied system header files (use
+ `-isystem' for that). If you use more than one `-I' option, the
+ directories are scanned in left-to-right order; the standard
+ system directories come after.
+
+ If a standard system include directory, or a directory specified
+ with `-isystem', is also specified with `-I', the `-I' option will
+ be ignored. The directory will still be searched but as a system
+ directory at its normal position in the system include chain.
+ This is to ensure that GCC's procedure to fix buggy system headers
+ and the ordering for the include_next directive are not
+ inadvertantly changed. If you really need to change the search
+ order for system directories, use the `-nostdinc' and/or
+ `-isystem' options.
+
+`-I-'
+ Any directories you specify with `-I' options before the `-I-'
+ option are searched only for the case of `#include "FILE"'; they
+ are not searched for `#include <FILE>'.
+
+ If additional directories are specified with `-I' options after
+ the `-I-', these directories are searched for all `#include'
+ directives. (Ordinarily _all_ `-I' directories are used this way.)
+
+ In addition, the `-I-' option inhibits the use of the current
+ directory (where the current input file came from) as the first
+ search directory for `#include "FILE"'. There is no way to
+ override this effect of `-I-'. With `-I.' you can specify
+ searching the directory which was current when the compiler was
+ invoked. That is not exactly the same as what the preprocessor
+ does by default, but it is often satisfactory.
+
+ `-I-' does not inhibit the use of the standard system directories
+ for header files. Thus, `-I-' and `-nostdinc' are independent.
+
+`-LDIR'
+ Add directory DIR to the list of directories to be searched for
+ `-l'.
+
+`-BPREFIX'
+ This option specifies where to find the executables, libraries,
+ include files, and data files of the compiler itself.
+
+ The compiler driver program runs one or more of the subprograms
+ `cpp', `cc1', `as' and `ld'. It tries PREFIX as a prefix for each
+ program it tries to run, both with and without `MACHINE/VERSION/'
+ (*note Target Options::).
+
+ For each subprogram to be run, the compiler driver first tries the
+ `-B' prefix, if any. If that name is not found, or if `-B' was
+ not specified, the driver tries two standard prefixes, which are
+ `/usr/lib/gcc/' and `/usr/local/lib/gcc-lib/'. If neither of
+ those results in a file name that is found, the unmodified program
+ name is searched for using the directories specified in your
+ `PATH' environment variable.
+
+ The compiler will check to see if the path provided by the `-B'
+ refers to a directory, and if necessary it will add a directory
+ separator character at the end of the path.
+
+ `-B' prefixes that effectively specify directory names also apply
+ to libraries in the linker, because the compiler translates these
+ options into `-L' options for the linker. They also apply to
+ includes files in the preprocessor, because the compiler
+ translates these options into `-isystem' options for the
+ preprocessor. In this case, the compiler appends `include' to the
+ prefix.
+
+ The run-time support file `libgcc.a' can also be searched for using
+ the `-B' prefix, if needed. If it is not found there, the two
+ standard prefixes above are tried, and that is all. The file is
+ left out of the link if it is not found by those means.
+
+ Another way to specify a prefix much like the `-B' prefix is to use
+ the environment variable `GCC_EXEC_PREFIX'. *Note Environment
+ Variables::.
+
+ As a special kludge, if the path provided by `-B' is
+ `[dir/]stageN/', where N is a number in the range 0 to 9, then it
+ will be replaced by `[dir/]include'. This is to help with
+ boot-strapping the compiler.
+
+`-specs=FILE'
+ Process FILE after the compiler reads in the standard `specs'
+ file, in order to override the defaults that the `gcc' driver
+ program uses when determining what switches to pass to `cc1',
+ `cc1plus', `as', `ld', etc. More than one `-specs=FILE' can be
+ specified on the command line, and they are processed in order,
+ from left to right.
+
+\1f
+File: gcc.info, Node: Spec Files, Next: Target Options, Prev: Directory Options, Up: Invoking GCC
+
+3.15 Specifying subprocesses and the switches to pass to them
+=============================================================
+
+`gcc' is a driver program. It performs its job by invoking a sequence
+of other programs to do the work of compiling, assembling and linking.
+GCC interprets its command-line parameters and uses these to deduce
+which programs it should invoke, and which command-line options it
+ought to place on their command lines. This behavior is controlled by
+"spec strings". In most cases there is one spec string for each
+program that GCC can invoke, but a few programs have multiple spec
+strings to control their behavior. The spec strings built into GCC can
+be overridden by using the `-specs=' command-line switch to specify a
+spec file.
+
+ "Spec files" are plaintext files that are used to construct spec
+strings. They consist of a sequence of directives separated by blank
+lines. The type of directive is determined by the first non-whitespace
+character on the line and it can be one of the following:
+
+`%COMMAND'
+ Issues a COMMAND to the spec file processor. The commands that can
+ appear here are:
+
+ `%include <FILE>'
+ Search for FILE and insert its text at the current point in
+ the specs file.
+
+ `%include_noerr <FILE>'
+ Just like `%include', but do not generate an error message if
+ the include file cannot be found.
+
+ `%rename OLD_NAME NEW_NAME'
+ Rename the spec string OLD_NAME to NEW_NAME.
+
+
+`*[SPEC_NAME]:'
+ This tells the compiler to create, override or delete the named
+ spec string. All lines after this directive up to the next
+ directive or blank line are considered to be the text for the spec
+ string. If this results in an empty string then the spec will be
+ deleted. (Or, if the spec did not exist, then nothing will
+ happened.) Otherwise, if the spec does not currently exist a new
+ spec will be created. If the spec does exist then its contents
+ will be overridden by the text of this directive, unless the first
+ character of that text is the `+' character, in which case the
+ text will be appended to the spec.
+
+`[SUFFIX]:'
+ Creates a new `[SUFFIX] spec' pair. All lines after this directive
+ and up to the next directive or blank line are considered to make
+ up the spec string for the indicated suffix. When the compiler
+ encounters an input file with the named suffix, it will processes
+ the spec string in order to work out how to compile that file.
+ For example:
+
+ .ZZ:
+ z-compile -input %i
+
+ This says that any input file whose name ends in `.ZZ' should be
+ passed to the program `z-compile', which should be invoked with the
+ command-line switch `-input' and with the result of performing the
+ `%i' substitution. (See below.)
+
+ As an alternative to providing a spec string, the text that
+ follows a suffix directive can be one of the following:
+
+ `@LANGUAGE'
+ This says that the suffix is an alias for a known LANGUAGE.
+ This is similar to using the `-x' command-line switch to GCC
+ to specify a language explicitly. For example:
+
+ .ZZ:
+ @c++
+
+ Says that .ZZ files are, in fact, C++ source files.
+
+ `#NAME'
+ This causes an error messages saying:
+
+ NAME compiler not installed on this system.
+
+ GCC already has an extensive list of suffixes built into it. This
+ directive will add an entry to the end of the list of suffixes, but
+ since the list is searched from the end backwards, it is
+ effectively possible to override earlier entries using this
+ technique.
+
+
+ GCC has the following spec strings built into it. Spec files can
+override these strings or create their own. Note that individual
+targets can also add their own spec strings to this list.
+
+ asm Options to pass to the assembler
+ asm_final Options to pass to the assembler post-processor
+ cpp Options to pass to the C preprocessor
+ cc1 Options to pass to the C compiler
+ cc1plus Options to pass to the C++ compiler
+ endfile Object files to include at the end of the link
+ link Options to pass to the linker
+ lib Libraries to include on the command line to the linker
+ libgcc Decides which GCC support library to pass to the linker
+ linker Sets the name of the linker
+ predefines Defines to be passed to the C preprocessor
+ signed_char Defines to pass to CPP to say whether `char' is signed
+ by default
+ startfile Object files to include at the start of the link
+
+ Here is a small example of a spec file:
+
+ %rename lib old_lib
+
+ *lib:
+ --start-group -lgcc -lc -leval1 --end-group %(old_lib)
+
+ This example renames the spec called `lib' to `old_lib' and then
+overrides the previous definition of `lib' with a new one. The new
+definition adds in some extra command-line options before including the
+text of the old definition.
+
+ "Spec strings" are a list of command-line options to be passed to
+their corresponding program. In addition, the spec strings can contain
+`%'-prefixed sequences to substitute variable text or to conditionally
+insert text into the command line. Using these constructs it is
+possible to generate quite complex command lines.
+
+ Here is a table of all defined `%'-sequences for spec strings. Note
+that spaces are not generated automatically around the results of
+expanding these sequences. Therefore you can concatenate them together
+or combine them with constant text in a single argument.
+
+`%%'
+ Substitute one `%' into the program name or argument.
+
+`%i'
+ Substitute the name of the input file being processed.
+
+`%b'
+ Substitute the basename of the input file being processed. This
+ is the substring up to (and not including) the last period and not
+ including the directory.
+
+`%B'
+ This is the same as `%b', but include the file suffix (text after
+ the last period).
+
+`%d'
+ Marks the argument containing or following the `%d' as a temporary
+ file name, so that that file will be deleted if GCC exits
+ successfully. Unlike `%g', this contributes no text to the
+ argument.
+
+`%gSUFFIX'
+ Substitute a file name that has suffix SUFFIX and is chosen once
+ per compilation, and mark the argument in the same way as `%d'.
+ To reduce exposure to denial-of-service attacks, the file name is
+ now chosen in a way that is hard to predict even when previously
+ chosen file names are known. For example, `%g.s ... %g.o ... %g.s'
+ might turn into `ccUVUUAU.s ccXYAXZ12.o ccUVUUAU.s'. SUFFIX
+ matches the regexp `[.A-Za-z]*' or the special string `%O', which
+ is treated exactly as if `%O' had been preprocessed. Previously,
+ `%g' was simply substituted with a file name chosen once per
+ compilation, without regard to any appended suffix (which was
+ therefore treated just like ordinary text), making such attacks
+ more likely to succeed.
+
+`%uSUFFIX'
+ Like `%g', but generates a new temporary file name even if
+ `%uSUFFIX' was already seen.
+
+`%USUFFIX'
+ Substitutes the last file name generated with `%uSUFFIX',
+ generating a new one if there is no such last file name. In the
+ absence of any `%uSUFFIX', this is just like `%gSUFFIX', except
+ they don't share the same suffix _space_, so `%g.s ... %U.s ...
+ %g.s ... %U.s' would involve the generation of two distinct file
+ names, one for each `%g.s' and another for each `%U.s'.
+ Previously, `%U' was simply substituted with a file name chosen
+ for the previous `%u', without regard to any appended suffix.
+
+`%jSUFFIX'
+ Substitutes the name of the `HOST_BIT_BUCKET', if any, and if it is
+ writable, and if save-temps is off; otherwise, substitute the name
+ of a temporary file, just like `%u'. This temporary file is not
+ meant for communication between processes, but rather as a junk
+ disposal mechanism.
+
+`%.SUFFIX'
+ Substitutes .SUFFIX for the suffixes of a matched switch's args
+ when it is subsequently output with `%*'. SUFFIX is terminated by
+ the next space or %.
+
+`%w'
+ Marks the argument containing or following the `%w' as the
+ designated output file of this compilation. This puts the argument
+ into the sequence of arguments that `%o' will substitute later.
+
+`%o'
+ Substitutes the names of all the output files, with spaces
+ automatically placed around them. You should write spaces around
+ the `%o' as well or the results are undefined. `%o' is for use in
+ the specs for running the linker. Input files whose names have no
+ recognized suffix are not compiled at all, but they are included
+ among the output files, so they will be linked.
+
+`%O'
+ Substitutes the suffix for object files. Note that this is
+ handled specially when it immediately follows `%g, %u, or %U',
+ because of the need for those to form complete file names. The
+ handling is such that `%O' is treated exactly as if it had already
+ been substituted, except that `%g, %u, and %U' do not currently
+ support additional SUFFIX characters following `%O' as they would
+ following, for example, `.o'.
+
+`%p'
+ Substitutes the standard macro predefinitions for the current
+ target machine. Use this when running `cpp'.
+
+`%P'
+ Like `%p', but puts `__' before and after the name of each
+ predefined macro, except for macros that start with `__' or with
+ `_L', where L is an uppercase letter. This is for ISO C.
+
+`%I'
+ Substitute a `-iprefix' option made from `GCC_EXEC_PREFIX'.
+
+`%s'
+ Current argument is the name of a library or startup file of some
+ sort. Search for that file in a standard list of directories and
+ substitute the full name found.
+
+`%eSTR'
+ Print STR as an error message. STR is terminated by a newline.
+ Use this when inconsistent options are detected.
+
+`%|'
+ Output `-' if the input for the current command is coming from a
+ pipe.
+
+`%(NAME)'
+ Substitute the contents of spec string NAME at this point.
+
+`%[NAME]'
+ Like `%(...)' but put `__' around `-D' arguments.
+
+`%x{OPTION}'
+ Accumulate an option for `%X'.
+
+`%X'
+ Output the accumulated linker options specified by `-Wl' or a `%x'
+ spec string.
+
+`%Y'
+ Output the accumulated assembler options specified by `-Wa'.
+
+`%Z'
+ Output the accumulated preprocessor options specified by `-Wp'.
+
+`%v1'
+ Substitute the major version number of GCC. (For version 2.9.5,
+ this is 2.)
+
+`%v2'
+ Substitute the minor version number of GCC. (For version 2.9.5,
+ this is 9.)
+
+`%v3'
+ Substitute the patch level number of GCC. (For version 2.9.5,
+ this is 5.)
+
+`%a'
+ Process the `asm' spec. This is used to compute the switches to
+ be passed to the assembler.
+
+`%A'
+ Process the `asm_final' spec. This is a spec string for passing
+ switches to an assembler post-processor, if such a program is
+ needed.
+
+`%l'
+ Process the `link' spec. This is the spec for computing the
+ command line passed to the linker. Typically it will make use of
+ the `%L %G %S %D and %E' sequences.
+
+`%D'
+ Dump out a `-L' option for each directory that GCC believes might
+ contain startup files. If the target supports multilibs then the
+ current multilib directory will be prepended to each of these
+ paths.
+
+`%M'
+ Output the multilib directory with directory separators replaced
+ with `_'. If multilib directories are not set, or the multilib
+ directory is `.' then this option emits nothing.
+
+`%L'
+ Process the `lib' spec. This is a spec string for deciding which
+ libraries should be included on the command line to the linker.
+
+`%G'
+ Process the `libgcc' spec. This is a spec string for deciding
+ which GCC support library should be included on the command line
+ to the linker.
+
+`%S'
+ Process the `startfile' spec. This is a spec for deciding which
+ object files should be the first ones passed to the linker.
+ Typically this might be a file named `crt0.o'.
+
+`%E'
+ Process the `endfile' spec. This is a spec string that specifies
+ the last object files that will be passed to the linker.
+
+`%C'
+ Process the `cpp' spec. This is used to construct the arguments
+ to be passed to the C preprocessor.
+
+`%c'
+ Process the `signed_char' spec. This is intended to be used to
+ tell cpp whether a char is signed. It typically has the
+ definition:
+ %{funsigned-char:-D__CHAR_UNSIGNED__}
+
+`%1'
+ Process the `cc1' spec. This is used to construct the options to
+ be passed to the actual C compiler (`cc1').
+
+`%2'
+ Process the `cc1plus' spec. This is used to construct the options
+ to be passed to the actual C++ compiler (`cc1plus').
+
+`%*'
+ Substitute the variable part of a matched option. See below.
+ Note that each comma in the substituted string is replaced by a
+ single space.
+
+`%{`S'}'
+ Substitutes the `-S' switch, if that switch was given to GCC. If
+ that switch was not specified, this substitutes nothing. Note that
+ the leading dash is omitted when specifying this option, and it is
+ automatically inserted if the substitution is performed. Thus the
+ spec string `%{foo}' would match the command-line option `-foo'
+ and would output the command line option `-foo'.
+
+`%W{`S'}'
+ Like %{`S'} but mark last argument supplied within as a file to be
+ deleted on failure.
+
+`%{`S'*}'
+ Substitutes all the switches specified to GCC whose names start
+ with `-S', but which also take an argument. This is used for
+ switches like `-o', `-D', `-I', etc. GCC considers `-o foo' as
+ being one switch whose names starts with `o'. %{o*} would
+ substitute this text, including the space. Thus two arguments
+ would be generated.
+
+`%{^`S'*}'
+ Like %{`S'*}, but don't put a blank between a switch and its
+ argument. Thus %{^o*} would only generate one argument, not two.
+
+`%{`S'*&`T'*}'
+ Like %{`S'*}, but preserve order of `S' and `T' options (the order
+ of `S' and `T' in the spec is not significant). There can be any
+ number of ampersand-separated variables; for each the wild card is
+ optional. Useful for CPP as `%{D*&U*&A*}'.
+
+`%{<`S'}'
+ Remove all occurrences of `-S' from the command line. Note--this
+ command is position dependent. `%' commands in the spec string
+ before this option will see `-S', `%' commands in the spec string
+ after this option will not.
+
+`%{`S'*:`X'}'
+ Substitutes `X' if one or more switches whose names start with
+ `-S' are specified to GCC. Note that the tail part of the `-S'
+ option (i.e. the part matched by the `*') will be substituted for
+ each occurrence of `%*' within `X'.
+
+`%{`S':`X'}'
+ Substitutes `X', but only if the `-S' switch was given to GCC.
+
+`%{!`S':`X'}'
+ Substitutes `X', but only if the `-S' switch was _not_ given to
+ GCC.
+
+`%{|`S':`X'}'
+ Like %{`S':`X'}, but if no `S' switch, substitute `-'.
+
+`%{|!`S':`X'}'
+ Like %{!`S':`X'}, but if there is an `S' switch, substitute `-'.
+
+`%{.`S':`X'}'
+ Substitutes `X', but only if processing a file with suffix `S'.
+
+`%{!.`S':`X'}'
+ Substitutes `X', but only if _not_ processing a file with suffix
+ `S'.
+
+`%{`S'|`P':`X'}'
+ Substitutes `X' if either `-S' or `-P' was given to GCC. This may
+ be combined with `!' and `.' sequences as well, although they have
+ a stronger binding than the `|'. For example a spec string like
+ this:
+
+ %{.c:-foo} %{!.c:-bar} %{.c|d:-baz} %{!.c|d:-boggle}
+
+ will output the following command-line options from the following
+ input command-line options:
+
+ fred.c -foo -baz
+ jim.d -bar -boggle
+ -d fred.c -foo -baz -boggle
+ -d jim.d -bar -baz -boggle
+
+
+ The conditional text `X' in a %{`S':`X'} or %{!`S':`X'} construct
+may contain other nested `%' constructs or spaces, or even newlines.
+They are processed as usual, as described above.
+
+ The `-O', `-f', `-m', and `-W' switches are handled specifically in
+these constructs. If another value of `-O' or the negated form of a
+`-f', `-m', or `-W' switch is found later in the command line, the
+earlier switch value is ignored, except with {`S'*} where `S' is just
+one letter, which passes all matching options.
+
+ The character `|' at the beginning of the predicate text is used to
+indicate that a command should be piped to the following command, but
+only if `-pipe' is specified.
+
+ It is built into GCC which switches take arguments and which do not.
+(You might think it would be useful to generalize this to allow each
+compiler's spec to say which switches take arguments. But this cannot
+be done in a consistent fashion. GCC cannot even decide which input
+files have been specified without knowing which switches take arguments,
+and it must know which input files to compile in order to tell which
+compilers to run).
+
+ GCC also knows implicitly that arguments starting in `-l' are to be
+treated as compiler output files, and passed to the linker in their
+proper position among the other output files.
+
+\1f
+File: gcc.info, Node: Target Options, Next: Submodel Options, Prev: Spec Files, Up: Invoking GCC
+
+3.16 Specifying Target Machine and Compiler Version
+===================================================
+
+By default, GCC compiles code for the same type of machine that you are
+using. However, it can also be installed as a cross-compiler, to
+compile for some other type of machine. In fact, several different
+configurations of GCC, for different target machines, can be installed
+side by side. Then you specify which one to use with the `-b' option.
+
+ In addition, older and newer versions of GCC can be installed side
+by side. One of them (probably the newest) will be the default, but
+you may sometimes wish to use another.
+
+`-b MACHINE'
+ The argument MACHINE specifies the target machine for compilation.
+ This is useful when you have installed GCC as a cross-compiler.
+
+ The value to use for MACHINE is the same as was specified as the
+ machine type when configuring GCC as a cross-compiler. For
+ example, if a cross-compiler was configured with `configure
+ i386v', meaning to compile for an 80386 running System V, then you
+ would specify `-b i386v' to run that cross compiler.
+
+ When you do not specify `-b', it normally means to compile for the
+ same type of machine that you are using.
+
+`-V VERSION'
+ The argument VERSION specifies which version of GCC to run. This
+ is useful when multiple versions are installed. For example,
+ VERSION might be `2.0', meaning to run GCC version 2.0.
+
+ The default version, when you do not specify `-V', is the last
+ version of GCC that you installed.
+
+ The `-b' and `-V' options actually work by controlling part of the
+file name used for the executable files and libraries used for
+compilation. A given version of GCC, for a given target machine, is
+normally kept in the directory `/usr/local/lib/gcc-lib/MACHINE/VERSION'.
+
+ Thus, sites can customize the effect of `-b' or `-V' either by
+changing the names of these directories or adding alternate names (or
+symbolic links). If in directory `/usr/local/lib/gcc-lib/' the file
+`80386' is a link to the file `i386v', then `-b 80386' becomes an alias
+for `-b i386v'.
+
+ In one respect, the `-b' or `-V' do not completely change to a
+different compiler: the top-level driver program `gcc' that you
+originally invoked continues to run and invoke the other executables
+(preprocessor, compiler per se, assembler and linker) that do the real
+work. However, since no real work is done in the driver program, it
+usually does not matter that the driver program in use is not the one
+for the specified target. It is common for the interface to the other
+executables to change incompatibly between compiler versions, so unless
+the version specified is very close to that of the driver (for example,
+`-V 3.0' with a driver program from GCC version 3.0.1), use of `-V' may
+not work; for example, using `-V 2.95.2' will not work with a driver
+program from GCC 3.0.
+
+ The only way that the driver program depends on the target machine is
+in the parsing and handling of special machine-specific options.
+However, this is controlled by a file which is found, along with the
+other executables, in the directory for the specified version and
+target machine. As a result, a single installed driver program adapts
+to any specified target machine, and sufficiently similar compiler
+versions.
+
+ The driver program executable does control one significant thing,
+however: the default version and target machine. Therefore, you can
+install different instances of the driver program, compiled for
+different targets or versions, under different names.
+
+ For example, if the driver for version 2.0 is installed as `ogcc'
+and that for version 2.1 is installed as `gcc', then the command `gcc'
+will use version 2.1 by default, while `ogcc' will use 2.0 by default.
+However, you can choose either version with either command with the
+`-V' option.
+
+\1f
+File: gcc.info, Node: Submodel Options, Next: Code Gen Options, Prev: Target Options, Up: Invoking GCC
+
+3.17 Hardware Models and Configurations
+=======================================
+
+Earlier we discussed the standard option `-b' which chooses among
+different installed compilers for completely different target machines,
+such as VAX vs. 68000 vs. 80386.
+
+ In addition, each of these target machine types can have its own
+special options, starting with `-m', to choose among various hardware
+models or configurations--for example, 68010 vs 68020, floating
+coprocessor or none. A single installed version of the compiler can
+compile for any model or configuration, according to the options
+specified.
+
+ Some configurations of the compiler also support additional special
+options, usually for compatibility with other compilers on the same
+platform.
+
+ These options are defined by the macro `TARGET_SWITCHES' in the
+machine description. The default for the options is also defined by
+that macro, which enables you to change the defaults.
+
+* Menu:
+
+* M680x0 Options::
+* M68hc1x Options::
+* VAX Options::
+* SPARC Options::
+* Convex Options::
+* AMD29K Options::
+* ARM Options::
+* MN10200 Options::
+* MN10300 Options::
+* M32R/D Options::
+* M88K Options::
+* RS/6000 and PowerPC Options::
+* RT Options::
+* MIPS Options::
+* i386 and x86-64 Options::
+* HPPA Options::
+* Intel 960 Options::
+* DEC Alpha Options::
+* DEC Alpha/VMS Options::
+* Clipper Options::
+* H8/300 Options::
+* SH Options::
+* System V Options::
+* TMS320C3x/C4x Options::
+* V850 Options::
+* ARC Options::
+* NS32K Options::
+* AVR Options::
+* MCore Options::
+* IA-64 Options::
+* D30V Options::
+* S/390 and zSeries Options::
+* CRIS Options::
+* MMIX Options::
+* PDP-11 Options::
+* Xstormy16 Options::
+* Xtensa Options::
+
+\1f
+File: gcc.info, Node: M680x0 Options, Next: M68hc1x Options, Up: Submodel Options
+
+3.17.1 M680x0 Options
+---------------------
+
+These are the `-m' options defined for the 68000 series. The default
+values for these options depends on which style of 68000 was selected
+when the compiler was configured; the defaults for the most common
+choices are given below.
+
+`-m68000'
+`-mc68000'
+ Generate output for a 68000. This is the default when the
+ compiler is configured for 68000-based systems.
+
+ Use this option for microcontrollers with a 68000 or EC000 core,
+ including the 68008, 68302, 68306, 68307, 68322, 68328 and 68356.
+
+`-m68020'
+`-mc68020'
+ Generate output for a 68020. This is the default when the
+ compiler is configured for 68020-based systems.
+
+`-m68881'
+ Generate output containing 68881 instructions for floating point.
+ This is the default for most 68020 systems unless `--nfp' was
+ specified when the compiler was configured.
+
+`-m68030'
+ Generate output for a 68030. This is the default when the
+ compiler is configured for 68030-based systems.
+
+`-m68040'
+ Generate output for a 68040. This is the default when the
+ compiler is configured for 68040-based systems.
+
+ This option inhibits the use of 68881/68882 instructions that have
+ to be emulated by software on the 68040. Use this option if your
+ 68040 does not have code to emulate those instructions.
+
+`-m68060'
+ Generate output for a 68060. This is the default when the
+ compiler is configured for 68060-based systems.
+
+ This option inhibits the use of 68020 and 68881/68882 instructions
+ that have to be emulated by software on the 68060. Use this
+ option if your 68060 does not have code to emulate those
+ instructions.
+
+`-mcpu32'
+ Generate output for a CPU32. This is the default when the
+ compiler is configured for CPU32-based systems.
+
+ Use this option for microcontrollers with a CPU32 or CPU32+ core,
+ including the 68330, 68331, 68332, 68333, 68334, 68336, 68340,
+ 68341, 68349 and 68360.
+
+`-m5200'
+ Generate output for a 520X "coldfire" family cpu. This is the
+ default when the compiler is configured for 520X-based systems.
+
+ Use this option for microcontroller with a 5200 core, including
+ the MCF5202, MCF5203, MCF5204 and MCF5202.
+
+`-m68020-40'
+ Generate output for a 68040, without using any of the new
+ instructions. This results in code which can run relatively
+ efficiently on either a 68020/68881 or a 68030 or a 68040. The
+ generated code does use the 68881 instructions that are emulated
+ on the 68040.
+
+`-m68020-60'
+ Generate output for a 68060, without using any of the new
+ instructions. This results in code which can run relatively
+ efficiently on either a 68020/68881 or a 68030 or a 68040. The
+ generated code does use the 68881 instructions that are emulated
+ on the 68060.
+
+`-mfpa'
+ Generate output containing Sun FPA instructions for floating point.
+
+`-msoft-float'
+ Generate output containing library calls for floating point.
+ *Warning:* the requisite libraries are not available for all m68k
+ targets. Normally the facilities of the machine's usual C
+ compiler are used, but this can't be done directly in
+ cross-compilation. You must make your own arrangements to provide
+ suitable library functions for cross-compilation. The embedded
+ targets `m68k-*-aout' and `m68k-*-coff' do provide software
+ floating point support.
+
+`-mshort'
+ Consider type `int' to be 16 bits wide, like `short int'.
+
+`-mnobitfield'
+ Do not use the bit-field instructions. The `-m68000', `-mcpu32'
+ and `-m5200' options imply `-mnobitfield'.
+
+`-mbitfield'
+ Do use the bit-field instructions. The `-m68020' option implies
+ `-mbitfield'. This is the default if you use a configuration
+ designed for a 68020.
+
+`-mrtd'
+ Use a different function-calling convention, in which functions
+ that take a fixed number of arguments return with the `rtd'
+ instruction, which pops their arguments while returning. This
+ saves one instruction in the caller since there is no need to pop
+ the arguments there.
+
+ This calling convention is incompatible with the one normally used
+ on Unix, so you cannot use it if you need to call libraries
+ compiled with the Unix compiler.
+
+ Also, you must provide function prototypes for all functions that
+ take variable numbers of arguments (including `printf'); otherwise
+ incorrect code will be generated for calls to those functions.
+
+ In addition, seriously incorrect code will result if you call a
+ function with too many arguments. (Normally, extra arguments are
+ harmlessly ignored.)
+
+ The `rtd' instruction is supported by the 68010, 68020, 68030,
+ 68040, 68060 and CPU32 processors, but not by the 68000 or 5200.
+
+`-malign-int'
+`-mno-align-int'
+ Control whether GCC aligns `int', `long', `long long', `float',
+ `double', and `long double' variables on a 32-bit boundary
+ (`-malign-int') or a 16-bit boundary (`-mno-align-int'). Aligning
+ variables on 32-bit boundaries produces code that runs somewhat
+ faster on processors with 32-bit busses at the expense of more
+ memory.
+
+ *Warning:* if you use the `-malign-int' switch, GCC will align
+ structures containing the above types differently than most
+ published application binary interface specifications for the m68k.
+
+`-mpcrel'
+ Use the pc-relative addressing mode of the 68000 directly, instead
+ of using a global offset table. At present, this option implies
+ `-fpic', allowing at most a 16-bit offset for pc-relative
+ addressing. `-fPIC' is not presently supported with `-mpcrel',
+ though this could be supported for 68020 and higher processors.
+
+`-mno-strict-align'
+`-mstrict-align'
+ Do not (do) assume that unaligned memory references will be
+ handled by the system.
+
+
+\1f
+File: gcc.info, Node: M68hc1x Options, Next: VAX Options, Prev: M680x0 Options, Up: Submodel Options
+
+3.17.2 M68hc1x Options
+----------------------
+
+These are the `-m' options defined for the 68hc11 and 68hc12
+microcontrollers. The default values for these options depends on
+which style of microcontroller was selected when the compiler was
+configured; the defaults for the most common choices are given below.
+
+`-m6811'
+`-m68hc11'
+ Generate output for a 68HC11. This is the default when the
+ compiler is configured for 68HC11-based systems.
+
+`-m6812'
+`-m68hc12'
+ Generate output for a 68HC12. This is the default when the
+ compiler is configured for 68HC12-based systems.
+
+`-mauto-incdec'
+ Enable the use of 68HC12 pre and post auto-increment and
+ auto-decrement addressing modes.
+
+`-mshort'
+ Consider type `int' to be 16 bits wide, like `short int'.
+
+`-msoft-reg-count=COUNT'
+ Specify the number of pseudo-soft registers which are used for the
+ code generation. The maximum number is 32. Using more pseudo-soft
+ register may or may not result in better code depending on the
+ program. The default is 4 for 68HC11 and 2 for 68HC12.
+
+
+\1f
+File: gcc.info, Node: VAX Options, Next: SPARC Options, Prev: M68hc1x Options, Up: Submodel Options
+
+3.17.3 VAX Options
+------------------
+
+These `-m' options are defined for the VAX:
+
+`-munix'
+ Do not output certain jump instructions (`aobleq' and so on) that
+ the Unix assembler for the VAX cannot handle across long ranges.
+
+`-mgnu'
+ Do output those jump instructions, on the assumption that you will
+ assemble with the GNU assembler.
+
+`-mg'
+ Output code for g-format floating point numbers instead of
+ d-format.
+
+\1f
+File: gcc.info, Node: SPARC Options, Next: Convex Options, Prev: VAX Options, Up: Submodel Options
+
+3.17.4 SPARC Options
+--------------------
+
+These `-m' switches are supported on the SPARC:
+
+`-mno-app-regs'
+`-mapp-regs'
+ Specify `-mapp-regs' to generate output using the global registers
+ 2 through 4, which the SPARC SVR4 ABI reserves for applications.
+ This is the default.
+
+ To be fully SVR4 ABI compliant at the cost of some performance
+ loss, specify `-mno-app-regs'. You should compile libraries and
+ system software with this option.
+
+`-mfpu'
+`-mhard-float'
+ Generate output containing floating point instructions. This is
+ the default.
+
+`-mno-fpu'
+`-msoft-float'
+ Generate output containing library calls for floating point.
+ *Warning:* the requisite libraries are not available for all SPARC
+ targets. Normally the facilities of the machine's usual C
+ compiler are used, but this cannot be done directly in
+ cross-compilation. You must make your own arrangements to provide
+ suitable library functions for cross-compilation. The embedded
+ targets `sparc-*-aout' and `sparclite-*-*' do provide software
+ floating point support.
+
+ `-msoft-float' changes the calling convention in the output file;
+ therefore, it is only useful if you compile _all_ of a program with
+ this option. In particular, you need to compile `libgcc.a', the
+ library that comes with GCC, with `-msoft-float' in order for this
+ to work.
+
+`-mhard-quad-float'
+ Generate output containing quad-word (long double) floating point
+ instructions.
+
+`-msoft-quad-float'
+ Generate output containing library calls for quad-word (long
+ double) floating point instructions. The functions called are
+ those specified in the SPARC ABI. This is the default.
+
+ As of this writing, there are no sparc implementations that have
+ hardware support for the quad-word floating point instructions.
+ They all invoke a trap handler for one of these instructions, and
+ then the trap handler emulates the effect of the instruction.
+ Because of the trap handler overhead, this is much slower than
+ calling the ABI library routines. Thus the `-msoft-quad-float'
+ option is the default.
+
+`-mno-flat'
+`-mflat'
+ With `-mflat', the compiler does not generate save/restore
+ instructions and will use a "flat" or single register window
+ calling convention. This model uses %i7 as the frame pointer and
+ is compatible with the normal register window model. Code from
+ either may be intermixed. The local registers and the input
+ registers (0-5) are still treated as "call saved" registers and
+ will be saved on the stack as necessary.
+
+ With `-mno-flat' (the default), the compiler emits save/restore
+ instructions (except for leaf functions) and is the normal mode of
+ operation.
+
+`-mno-unaligned-doubles'
+`-munaligned-doubles'
+ Assume that doubles have 8 byte alignment. This is the default.
+
+ With `-munaligned-doubles', GCC assumes that doubles have 8 byte
+ alignment only if they are contained in another type, or if they
+ have an absolute address. Otherwise, it assumes they have 4 byte
+ alignment. Specifying this option avoids some rare compatibility
+ problems with code generated by other compilers. It is not the
+ default because it results in a performance loss, especially for
+ floating point code.
+
+`-mno-faster-structs'
+`-mfaster-structs'
+ With `-mfaster-structs', the compiler assumes that structures
+ should have 8 byte alignment. This enables the use of pairs of
+ `ldd' and `std' instructions for copies in structure assignment,
+ in place of twice as many `ld' and `st' pairs. However, the use
+ of this changed alignment directly violates the Sparc ABI. Thus,
+ it's intended only for use on targets where the developer
+ acknowledges that their resulting code will not be directly in
+ line with the rules of the ABI.
+
+`-mv8'
+`-msparclite'
+ These two options select variations on the SPARC architecture.
+
+ By default (unless specifically configured for the Fujitsu
+ SPARClite), GCC generates code for the v7 variant of the SPARC
+ architecture.
+
+ `-mv8' will give you SPARC v8 code. The only difference from v7
+ code is that the compiler emits the integer multiply and integer
+ divide instructions which exist in SPARC v8 but not in SPARC v7.
+
+ `-msparclite' will give you SPARClite code. This adds the integer
+ multiply, integer divide step and scan (`ffs') instructions which
+ exist in SPARClite but not in SPARC v7.
+
+ These options are deprecated and will be deleted in a future GCC
+ release. They have been replaced with `-mcpu=xxx'.
+
+`-mcypress'
+`-msupersparc'
+ These two options select the processor for which the code is
+ optimized.
+
+ With `-mcypress' (the default), the compiler optimizes code for the
+ Cypress CY7C602 chip, as used in the SparcStation/SparcServer 3xx
+ series. This is also appropriate for the older SparcStation 1, 2,
+ IPX etc.
+
+ With `-msupersparc' the compiler optimizes code for the SuperSparc
+ cpu, as used in the SparcStation 10, 1000 and 2000 series. This
+ flag also enables use of the full SPARC v8 instruction set.
+
+ These options are deprecated and will be deleted in a future GCC
+ release. They have been replaced with `-mcpu=xxx'.
+
+`-mcpu=CPU_TYPE'
+ Set the instruction set, register set, and instruction scheduling
+ parameters for machine type CPU_TYPE. Supported values for
+ CPU_TYPE are `v7', `cypress', `v8', `supersparc', `sparclite',
+ `hypersparc', `sparclite86x', `f930', `f934', `sparclet',
+ `tsc701', `v9', and `ultrasparc'.
+
+ Default instruction scheduling parameters are used for values that
+ select an architecture and not an implementation. These are `v7',
+ `v8', `sparclite', `sparclet', `v9'.
+
+ Here is a list of each supported architecture and their supported
+ implementations.
+
+ v7: cypress
+ v8: supersparc, hypersparc
+ sparclite: f930, f934, sparclite86x
+ sparclet: tsc701
+ v9: ultrasparc
+
+`-mtune=CPU_TYPE'
+ Set the instruction scheduling parameters for machine type
+ CPU_TYPE, but do not set the instruction set or register set that
+ the option `-mcpu=CPU_TYPE' would.
+
+ The same values for `-mcpu=CPU_TYPE' can be used for
+ `-mtune=CPU_TYPE', but the only useful values are those that
+ select a particular cpu implementation. Those are `cypress',
+ `supersparc', `hypersparc', `f930', `f934', `sparclite86x',
+ `tsc701', and `ultrasparc'.
+
+
+ These `-m' switches are supported in addition to the above on the
+SPARCLET processor.
+
+`-mlittle-endian'
+ Generate code for a processor running in little-endian mode.
+
+`-mlive-g0'
+ Treat register `%g0' as a normal register. GCC will continue to
+ clobber it as necessary but will not assume it always reads as 0.
+
+`-mbroken-saverestore'
+ Generate code that does not use non-trivial forms of the `save' and
+ `restore' instructions. Early versions of the SPARCLET processor
+ do not correctly handle `save' and `restore' instructions used with
+ arguments. They correctly handle them used without arguments. A
+ `save' instruction used without arguments increments the current
+ window pointer but does not allocate a new stack frame. It is
+ assumed that the window overflow trap handler will properly handle
+ this case as will interrupt handlers.
+
+ These `-m' switches are supported in addition to the above on SPARC
+V9 processors in 64-bit environments.
+
+`-mlittle-endian'
+ Generate code for a processor running in little-endian mode.
+
+`-m32'
+`-m64'
+ Generate code for a 32-bit or 64-bit environment. The 32-bit
+ environment sets int, long and pointer to 32 bits. The 64-bit
+ environment sets int to 32 bits and long and pointer to 64 bits.
+
+`-mcmodel=medlow'
+ Generate code for the Medium/Low code model: the program must be
+ linked in the low 32 bits of the address space. Pointers are 64
+ bits. Programs can be statically or dynamically linked.
+
+`-mcmodel=medmid'
+ Generate code for the Medium/Middle code model: the program must
+ be linked in the low 44 bits of the address space, the text
+ segment must be less than 2G bytes, and data segment must be
+ within 2G of the text segment. Pointers are 64 bits.
+
+`-mcmodel=medany'
+ Generate code for the Medium/Anywhere code model: the program may
+ be linked anywhere in the address space, the text segment must be
+ less than 2G bytes, and data segment must be within 2G of the text
+ segment. Pointers are 64 bits.
+
+`-mcmodel=embmedany'
+ Generate code for the Medium/Anywhere code model for embedded
+ systems: assume a 32-bit text and a 32-bit data segment, both
+ starting anywhere (determined at link time). Register %g4 points
+ to the base of the data segment. Pointers are still 64 bits.
+ Programs are statically linked, PIC is not supported.
+
+`-mstack-bias'
+`-mno-stack-bias'
+ With `-mstack-bias', GCC assumes that the stack pointer, and frame
+ pointer if present, are offset by -2047 which must be added back
+ when making stack frame references. Otherwise, assume no such
+ offset is present.
+
+\1f
+File: gcc.info, Node: Convex Options, Next: AMD29K Options, Prev: SPARC Options, Up: Submodel Options
+
+3.17.5 Convex Options
+---------------------
+
+These `-m' options are defined for Convex:
+
+`-mc1'
+ Generate output for C1. The code will run on any Convex machine.
+ The preprocessor symbol `__convex__c1__' is defined.
+
+`-mc2'
+ Generate output for C2. Uses instructions not available on C1.
+ Scheduling and other optimizations are chosen for max performance
+ on C2. The preprocessor symbol `__convex_c2__' is defined.
+
+`-mc32'
+ Generate output for C32xx. Uses instructions not available on C1.
+ Scheduling and other optimizations are chosen for max performance
+ on C32. The preprocessor symbol `__convex_c32__' is defined.
+
+`-mc34'
+ Generate output for C34xx. Uses instructions not available on C1.
+ Scheduling and other optimizations are chosen for max performance
+ on C34. The preprocessor symbol `__convex_c34__' is defined.
+
+`-mc38'
+ Generate output for C38xx. Uses instructions not available on C1.
+ Scheduling and other optimizations are chosen for max performance
+ on C38. The preprocessor symbol `__convex_c38__' is defined.
+
+`-margcount'
+ Generate code which puts an argument count in the word preceding
+ each argument list. This is compatible with regular CC, and a few
+ programs may need the argument count word. GDB and other
+ source-level debuggers do not need it; this info is in the symbol
+ table.
+
+`-mnoargcount'
+ Omit the argument count word. This is the default.
+
+`-mvolatile-cache'
+ Allow volatile references to be cached. This is the default.
+
+`-mvolatile-nocache'
+ Volatile references bypass the data cache, going all the way to
+ memory. This is only needed for multi-processor code that does
+ not use standard synchronization instructions. Making
+ non-volatile references to volatile locations will not necessarily
+ work.
+
+`-mlong32'
+ Type long is 32 bits, the same as type int. This is the default.
+
+`-mlong64'
+ Type long is 64 bits, the same as type long long. This option is
+ useless, because no library support exists for it.
+
+\1f
+File: gcc.info, Node: AMD29K Options, Next: ARM Options, Prev: Convex Options, Up: Submodel Options
+
+3.17.6 AMD29K Options
+---------------------
+
+These `-m' options are defined for the AMD Am29000:
+
+`-mdw'
+ Generate code that assumes the `DW' bit is set, i.e., that byte and
+ halfword operations are directly supported by the hardware. This
+ is the default.
+
+`-mndw'
+ Generate code that assumes the `DW' bit is not set.
+
+`-mbw'
+ Generate code that assumes the system supports byte and halfword
+ write operations. This is the default.
+
+`-mnbw'
+ Generate code that assumes the systems does not support byte and
+ halfword write operations. `-mnbw' implies `-mndw'.
+
+`-msmall'
+ Use a small memory model that assumes that all function addresses
+ are either within a single 256 KB segment or at an absolute
+ address of less than 256k. This allows the `call' instruction to
+ be used instead of a `const', `consth', `calli' sequence.
+
+`-mnormal'
+ Use the normal memory model: Generate `call' instructions only when
+ calling functions in the same file and `calli' instructions
+ otherwise. This works if each file occupies less than 256 KB but
+ allows the entire executable to be larger than 256 KB. This is
+ the default.
+
+`-mlarge'
+ Always use `calli' instructions. Specify this option if you expect
+ a single file to compile into more than 256 KB of code.
+
+`-m29050'
+ Generate code for the Am29050.
+
+`-m29000'
+ Generate code for the Am29000. This is the default.
+
+`-mkernel-registers'
+ Generate references to registers `gr64-gr95' instead of to
+ registers `gr96-gr127'. This option can be used when compiling
+ kernel code that wants a set of global registers disjoint from
+ that used by user-mode code.
+
+ Note that when this option is used, register names in `-f' flags
+ must use the normal, user-mode, names.
+
+`-muser-registers'
+ Use the normal set of global registers, `gr96-gr127'. This is the
+ default.
+
+`-mstack-check'
+`-mno-stack-check'
+ Insert (or do not insert) a call to `__msp_check' after each stack
+ adjustment. This is often used for kernel code.
+
+`-mstorem-bug'
+`-mno-storem-bug'
+ `-mstorem-bug' handles 29k processors which cannot handle the
+ separation of a mtsrim insn and a storem instruction (most 29000
+ chips to date, but not the 29050).
+
+`-mno-reuse-arg-regs'
+`-mreuse-arg-regs'
+ `-mno-reuse-arg-regs' tells the compiler to only use incoming
+ argument registers for copying out arguments. This helps detect
+ calling a function with fewer arguments than it was declared with.
+
+`-mno-impure-text'
+`-mimpure-text'
+ `-mimpure-text', used in addition to `-shared', tells the compiler
+ to not pass `-assert pure-text' to the linker when linking a
+ shared object.
+
+`-msoft-float'
+ Generate output containing library calls for floating point.
+ *Warning:* the requisite libraries are not part of GCC. Normally
+ the facilities of the machine's usual C compiler are used, but
+ this can't be done directly in cross-compilation. You must make
+ your own arrangements to provide suitable library functions for
+ cross-compilation.
+
+`-mno-multm'
+ Do not generate multm or multmu instructions. This is useful for
+ some embedded systems which do not have trap handlers for these
+ instructions.
+
+\1f
+File: gcc.info, Node: ARM Options, Next: MN10200 Options, Prev: AMD29K Options, Up: Submodel Options
+
+3.17.7 ARM Options
+------------------
+
+These `-m' options are defined for Advanced RISC Machines (ARM)
+architectures:
+
+`-mapcs-frame'
+ Generate a stack frame that is compliant with the ARM Procedure
+ Call Standard for all functions, even if this is not strictly
+ necessary for correct execution of the code. Specifying
+ `-fomit-frame-pointer' with this option will cause the stack
+ frames not to be generated for leaf functions. The default is
+ `-mno-apcs-frame'.
+
+`-mapcs'
+ This is a synonym for `-mapcs-frame'.
+
+`-mapcs-26'
+ Generate code for a processor running with a 26-bit program
+ counter, and conforming to the function calling standards for the
+ APCS 26-bit option. This option replaces the `-m2' and `-m3'
+ options of previous releases of the compiler.
+
+`-mapcs-32'
+ Generate code for a processor running with a 32-bit program
+ counter, and conforming to the function calling standards for the
+ APCS 32-bit option. This option replaces the `-m6' option of
+ previous releases of the compiler.
+
+`-mthumb-interwork'
+ Generate code which supports calling between the ARM and Thumb
+ instruction sets. Without this option the two instruction sets
+ cannot be reliably used inside one program. The default is
+ `-mno-thumb-interwork', since slightly larger code is generated
+ when `-mthumb-interwork' is specified.
+
+`-mno-sched-prolog'
+ Prevent the reordering of instructions in the function prolog, or
+ the merging of those instruction with the instructions in the
+ function's body. This means that all functions will start with a
+ recognizable set of instructions (or in fact one of a choice from
+ a small set of different function prologues), and this information
+ can be used to locate the start if functions inside an executable
+ piece of code. The default is `-msched-prolog'.
+
+`-mhard-float'
+ Generate output containing floating point instructions. This is
+ the default.
+
+`-msoft-float'
+ Generate output containing library calls for floating point.
+ *Warning:* the requisite libraries are not available for all ARM
+ targets. Normally the facilities of the machine's usual C
+ compiler are used, but this cannot be done directly in
+ cross-compilation. You must make your own arrangements to provide
+ suitable library functions for cross-compilation.
+
+ `-msoft-float' changes the calling convention in the output file;
+ therefore, it is only useful if you compile _all_ of a program with
+ this option. In particular, you need to compile `libgcc.a', the
+ library that comes with GCC, with `-msoft-float' in order for this
+ to work.
+
+`-mlittle-endian'
+ Generate code for a processor running in little-endian mode. This
+ is the default for all standard configurations.
+
+`-mbig-endian'
+ Generate code for a processor running in big-endian mode; the
+ default is to compile code for a little-endian processor.
+
+`-mwords-little-endian'
+ This option only applies when generating code for big-endian
+ processors. Generate code for a little-endian word order but a
+ big-endian byte order. That is, a byte order of the form
+ `32107654'. Note: this option should only be used if you require
+ compatibility with code for big-endian ARM processors generated by
+ versions of the compiler prior to 2.8.
+
+`-malignment-traps'
+ Generate code that will not trap if the MMU has alignment traps
+ enabled. On ARM architectures prior to ARMv4, there were no
+ instructions to access half-word objects stored in memory.
+ However, when reading from memory a feature of the ARM
+ architecture allows a word load to be used, even if the address is
+ unaligned, and the processor core will rotate the data as it is
+ being loaded. This option tells the compiler that such misaligned
+ accesses will cause a MMU trap and that it should instead
+ synthesise the access as a series of byte accesses. The compiler
+ can still use word accesses to load half-word data if it knows
+ that the address is aligned to a word boundary.
+
+ This option is ignored when compiling for ARM architecture 4 or
+ later, since these processors have instructions to directly access
+ half-word objects in memory.
+
+`-mno-alignment-traps'
+ Generate code that assumes that the MMU will not trap unaligned
+ accesses. This produces better code when the target instruction
+ set does not have half-word memory operations (i.e.
+ implementations prior to ARMv4).
+
+ Note that you cannot use this option to access unaligned word
+ objects, since the processor will only fetch one 32-bit aligned
+ object from memory.
+
+ The default setting for most targets is `-mno-alignment-traps',
+ since this produces better code when there are no half-word memory
+ instructions available.
+
+`-mshort-load-bytes'
+`-mno-short-load-words'
+ These are deprecated aliases for `-malignment-traps'.
+
+`-mno-short-load-bytes'
+`-mshort-load-words'
+ This are deprecated aliases for `-mno-alignment-traps'.
+
+`-mbsd'
+ This option only applies to RISC iX. Emulate the native BSD-mode
+ compiler. This is the default if `-ansi' is not specified.
+
+`-mxopen'
+ This option only applies to RISC iX. Emulate the native
+ X/Open-mode compiler.
+
+`-mno-symrename'
+ This option only applies to RISC iX. Do not run the assembler
+ post-processor, `symrename', after code has been assembled.
+ Normally it is necessary to modify some of the standard symbols in
+ preparation for linking with the RISC iX C library; this option
+ suppresses this pass. The post-processor is never run when the
+ compiler is built for cross-compilation.
+
+`-mcpu=NAME'
+ This specifies the name of the target ARM processor. GCC uses
+ this name to determine what kind of instructions it can emit when
+ generating assembly code. Permissible names are: `arm2', `arm250',
+ `arm3', `arm6', `arm60', `arm600', `arm610', `arm620', `arm7',
+ `arm7m', `arm7d', `arm7dm', `arm7di', `arm7dmi', `arm70', `arm700',
+ `arm700i', `arm710', `arm710c', `arm7100', `arm7500', `arm7500fe',
+ `arm7tdmi', `arm8', `strongarm', `strongarm110', `strongarm1100',
+ `arm8', `arm810', `arm9', `arm9e', `arm920', `arm920t', `arm940t',
+ `arm9tdmi', `arm10tdmi', `arm1020t', `xscale'.
+
+`-mtune=NAME'
+ This option is very similar to the `-mcpu=' option, except that
+ instead of specifying the actual target processor type, and hence
+ restricting which instructions can be used, it specifies that GCC
+ should tune the performance of the code as if the target were of
+ the type specified in this option, but still choosing the
+ instructions that it will generate based on the cpu specified by a
+ `-mcpu=' option. For some ARM implementations better performance
+ can be obtained by using this option.
+
+`-march=NAME'
+ This specifies the name of the target ARM architecture. GCC uses
+ this name to determine what kind of instructions it can emit when
+ generating assembly code. This option can be used in conjunction
+ with or instead of the `-mcpu=' option. Permissible names are:
+ `armv2', `armv2a', `armv3', `armv3m', `armv4', `armv4t', `armv5',
+ `armv5t', `armv5te'.
+
+`-mfpe=NUMBER'
+`-mfp=NUMBER'
+ This specifies the version of the floating point emulation
+ available on the target. Permissible values are 2 and 3. `-mfp='
+ is a synonym for `-mfpe=', for compatibility with older versions
+ of GCC.
+
+`-mstructure-size-boundary=N'
+ The size of all structures and unions will be rounded up to a
+ multiple of the number of bits set by this option. Permissible
+ values are 8 and 32. The default value varies for different
+ toolchains. For the COFF targeted toolchain the default value is
+ 8. Specifying the larger number can produce faster, more
+ efficient code, but can also increase the size of the program.
+ The two values are potentially incompatible. Code compiled with
+ one value cannot necessarily expect to work with code or libraries
+ compiled with the other value, if they exchange information using
+ structures or unions.
+
+`-mabort-on-noreturn'
+ Generate a call to the function `abort' at the end of a `noreturn'
+ function. It will be executed if the function tries to return.
+
+`-mlong-calls'
+`-mno-long-calls'
+ Tells the compiler to perform function calls by first loading the
+ address of the function into a register and then performing a
+ subroutine call on this register. This switch is needed if the
+ target function will lie outside of the 64 megabyte addressing
+ range of the offset based version of subroutine call instruction.
+
+ Even if this switch is enabled, not all function calls will be
+ turned into long calls. The heuristic is that static functions,
+ functions which have the `short-call' attribute, functions that
+ are inside the scope of a `#pragma no_long_calls' directive and
+ functions whose definitions have already been compiled within the
+ current compilation unit, will not be turned into long calls. The
+ exception to this rule is that weak function definitions,
+ functions with the `long-call' attribute or the `section'
+ attribute, and functions that are within the scope of a `#pragma
+ long_calls' directive, will always be turned into long calls.
+
+ This feature is not enabled by default. Specifying
+ `-mno-long-calls' will restore the default behavior, as will
+ placing the function calls within the scope of a `#pragma
+ long_calls_off' directive. Note these switches have no effect on
+ how the compiler generates code to handle function calls via
+ function pointers.
+
+`-mnop-fun-dllimport'
+ Disable support for the `dllimport' attribute.
+
+`-msingle-pic-base'
+ Treat the register used for PIC addressing as read-only, rather
+ than loading it in the prologue for each function. The run-time
+ system is responsible for initializing this register with an
+ appropriate value before execution begins.
+
+`-mpic-register=REG'
+ Specify the register to be used for PIC addressing. The default
+ is R10 unless stack-checking is enabled, when R9 is used.
+
+`-mpoke-function-name'
+ Write the name of each function into the text section, directly
+ preceding the function prologue. The generated code is similar to
+ this:
+
+ t0
+ .ascii "arm_poke_function_name", 0
+ .align
+ t1
+ .word 0xff000000 + (t1 - t0)
+ arm_poke_function_name
+ mov ip, sp
+ stmfd sp!, {fp, ip, lr, pc}
+ sub fp, ip, #4
+
+ When performing a stack backtrace, code can inspect the value of
+ `pc' stored at `fp + 0'. If the trace function then looks at
+ location `pc - 12' and the top 8 bits are set, then we know that
+ there is a function name embedded immediately preceding this
+ location and has length `((pc[-3]) & 0xff000000)'.
+
+`-mthumb'
+ Generate code for the 16-bit Thumb instruction set. The default
+ is to use the 32-bit ARM instruction set.
+
+`-mtpcs-frame'
+ Generate a stack frame that is compliant with the Thumb Procedure
+ Call Standard for all non-leaf functions. (A leaf function is one
+ that does not call any other functions.) The default is
+ `-mno-tpcs-frame'.
+
+`-mtpcs-leaf-frame'
+ Generate a stack frame that is compliant with the Thumb Procedure
+ Call Standard for all leaf functions. (A leaf function is one
+ that does not call any other functions.) The default is
+ `-mno-apcs-leaf-frame'.
+
+`-mcallee-super-interworking'
+ Gives all externally visible functions in the file being compiled
+ an ARM instruction set header which switches to Thumb mode before
+ executing the rest of the function. This allows these functions
+ to be called from non-interworking code.
+
+`-mcaller-super-interworking'
+ Allows calls via function pointers (including virtual functions) to
+ execute correctly regardless of whether the target code has been
+ compiled for interworking or not. There is a small overhead in
+ the cost of executing a function pointer if this option is enabled.
+
+
+\1f
+File: gcc.info, Node: MN10200 Options, Next: MN10300 Options, Prev: ARM Options, Up: Submodel Options
+
+3.17.8 MN10200 Options
+----------------------
+
+These `-m' options are defined for Matsushita MN10200 architectures:
+`-mrelax'
+ Indicate to the linker that it should perform a relaxation
+ optimization pass to shorten branches, calls and absolute memory
+ addresses. This option only has an effect when used on the
+ command line for the final link step.
+
+ This option makes symbolic debugging impossible.
+
+\1f
+File: gcc.info, Node: MN10300 Options, Next: M32R/D Options, Prev: MN10200 Options, Up: Submodel Options
+
+3.17.9 MN10300 Options
+----------------------
+
+These `-m' options are defined for Matsushita MN10300 architectures:
+
+`-mmult-bug'
+ Generate code to avoid bugs in the multiply instructions for the
+ MN10300 processors. This is the default.
+
+`-mno-mult-bug'
+ Do not generate code to avoid bugs in the multiply instructions
+ for the MN10300 processors.
+
+`-mam33'
+ Generate code which uses features specific to the AM33 processor.
+
+`-mno-am33'
+ Do not generate code which uses features specific to the AM33
+ processor. This is the default.
+
+`-mno-crt0'
+ Do not link in the C run-time initialization object file.
+
+`-mrelax'
+ Indicate to the linker that it should perform a relaxation
+ optimization pass to shorten branches, calls and absolute memory
+ addresses. This option only has an effect when used on the
+ command line for the final link step.
+
+ This option makes symbolic debugging impossible.
+
+\1f
+File: gcc.info, Node: M32R/D Options, Next: M88K Options, Prev: MN10300 Options, Up: Submodel Options
+
+3.17.10 M32R/D Options
+----------------------
+
+These `-m' options are defined for Mitsubishi M32R/D architectures:
+
+`-m32rx'
+ Generate code for the M32R/X.
+
+`-m32r'
+ Generate code for the M32R. This is the default.
+
+`-mcode-model=small'
+ Assume all objects live in the lower 16MB of memory (so that their
+ addresses can be loaded with the `ld24' instruction), and assume
+ all subroutines are reachable with the `bl' instruction. This is
+ the default.
+
+ The addressability of a particular object can be set with the
+ `model' attribute.
+
+`-mcode-model=medium'
+ Assume objects may be anywhere in the 32-bit address space (the
+ compiler will generate `seth/add3' instructions to load their
+ addresses), and assume all subroutines are reachable with the `bl'
+ instruction.
+
+`-mcode-model=large'
+ Assume objects may be anywhere in the 32-bit address space (the
+ compiler will generate `seth/add3' instructions to load their
+ addresses), and assume subroutines may not be reachable with the
+ `bl' instruction (the compiler will generate the much slower
+ `seth/add3/jl' instruction sequence).
+
+`-msdata=none'
+ Disable use of the small data area. Variables will be put into
+ one of `.data', `bss', or `.rodata' (unless the `section'
+ attribute has been specified). This is the default.
+
+ The small data area consists of sections `.sdata' and `.sbss'.
+ Objects may be explicitly put in the small data area with the
+ `section' attribute using one of these sections.
+
+`-msdata=sdata'
+ Put small global and static data in the small data area, but do not
+ generate special code to reference them.
+
+`-msdata=use'
+ Put small global and static data in the small data area, and
+ generate special instructions to reference them.
+
+`-G NUM'
+ Put global and static objects less than or equal to NUM bytes into
+ the small data or bss sections instead of the normal data or bss
+ sections. The default value of NUM is 8. The `-msdata' option
+ must be set to one of `sdata' or `use' for this option to have any
+ effect.
+
+ All modules should be compiled with the same `-G NUM' value.
+ Compiling with different values of NUM may or may not work; if it
+ doesn't the linker will give an error message--incorrect code will
+ not be generated.
+
+
+\1f
+File: gcc.info, Node: M88K Options, Next: RS/6000 and PowerPC Options, Prev: M32R/D Options, Up: Submodel Options
+
+3.17.11 M88K Options
+--------------------
+
+These `-m' options are defined for Motorola 88k architectures:
+
+`-m88000'
+ Generate code that works well on both the m88100 and the m88110.
+
+`-m88100'
+ Generate code that works best for the m88100, but that also runs
+ on the m88110.
+
+`-m88110'
+ Generate code that works best for the m88110, and may not run on
+ the m88100.
+
+`-mbig-pic'
+ Obsolete option to be removed from the next revision. Use `-fPIC'.
+
+`-midentify-revision'
+ Include an `ident' directive in the assembler output recording the
+ source file name, compiler name and version, timestamp, and
+ compilation flags used.
+
+`-mno-underscores'
+ In assembler output, emit symbol names without adding an underscore
+ character at the beginning of each name. The default is to use an
+ underscore as prefix on each name.
+
+`-mocs-debug-info'
+`-mno-ocs-debug-info'
+ Include (or omit) additional debugging information (about
+ registers used in each stack frame) as specified in the 88open
+ Object Compatibility Standard, "OCS". This extra information
+ allows debugging of code that has had the frame pointer
+ eliminated. The default for DG/UX, SVr4, and Delta 88 SVr3.2 is
+ to include this information; other 88k configurations omit this
+ information by default.
+
+`-mocs-frame-position'
+ When emitting COFF debugging information for automatic variables
+ and parameters stored on the stack, use the offset from the
+ canonical frame address, which is the stack pointer (register 31)
+ on entry to the function. The DG/UX, SVr4, Delta88 SVr3.2, and
+ BCS configurations use `-mocs-frame-position'; other 88k
+ configurations have the default `-mno-ocs-frame-position'.
+
+`-mno-ocs-frame-position'
+ When emitting COFF debugging information for automatic variables
+ and parameters stored on the stack, use the offset from the frame
+ pointer register (register 30). When this option is in effect,
+ the frame pointer is not eliminated when debugging information is
+ selected by the -g switch.
+
+`-moptimize-arg-area'
+ Save space by reorganizing the stack frame. This option generates
+ code that does not agree with the 88open specifications, but uses
+ less memory.
+
+`-mno-optimize-arg-area'
+ Do not reorganize the stack frame to save space. This is the
+ default. The generated conforms to the specification, but uses
+ more memory.
+
+`-mshort-data-NUM'
+ Generate smaller data references by making them relative to `r0',
+ which allows loading a value using a single instruction (rather
+ than the usual two). You control which data references are
+ affected by specifying NUM with this option. For example, if you
+ specify `-mshort-data-512', then the data references affected are
+ those involving displacements of less than 512 bytes.
+ `-mshort-data-NUM' is not effective for NUM greater than 64k.
+
+`-mserialize-volatile'
+`-mno-serialize-volatile'
+ Do, or don't, generate code to guarantee sequential consistency of
+ volatile memory references. By default, consistency is guaranteed.
+
+ The order of memory references made by the MC88110 processor does
+ not always match the order of the instructions requesting those
+ references. In particular, a load instruction may execute before
+ a preceding store instruction. Such reordering violates
+ sequential consistency of volatile memory references, when there
+ are multiple processors. When consistency must be guaranteed,
+ GCC generates special instructions, as needed, to force execution
+ in the proper order.
+
+ The MC88100 processor does not reorder memory references and so
+ always provides sequential consistency. However, by default, GCC
+ generates the special instructions to guarantee consistency even
+ when you use `-m88100', so that the code may be run on an MC88110
+ processor. If you intend to run your code only on the MC88100
+ processor, you may use `-mno-serialize-volatile'.
+
+ The extra code generated to guarantee consistency may affect the
+ performance of your application. If you know that you can safely
+ forgo this guarantee, you may use `-mno-serialize-volatile'.
+
+`-msvr4'
+`-msvr3'
+ Turn on (`-msvr4') or off (`-msvr3') compiler extensions related
+ to System V release 4 (SVr4). This controls the following:
+
+ 1. Which variant of the assembler syntax to emit.
+
+ 2. `-msvr4' makes the C preprocessor recognize `#pragma weak'
+ that is used on System V release 4.
+
+ 3. `-msvr4' makes GCC issue additional declaration directives
+ used in SVr4.
+
+ `-msvr4' is the default for the m88k-motorola-sysv4 and
+ m88k-dg-dgux m88k configurations. `-msvr3' is the default for all
+ other m88k configurations.
+
+`-mversion-03.00'
+ This option is obsolete, and is ignored.
+
+`-mno-check-zero-division'
+`-mcheck-zero-division'
+ Do, or don't, generate code to guarantee that integer division by
+ zero will be detected. By default, detection is guaranteed.
+
+ Some models of the MC88100 processor fail to trap upon integer
+ division by zero under certain conditions. By default, when
+ compiling code that might be run on such a processor, GCC
+ generates code that explicitly checks for zero-valued divisors and
+ traps with exception number 503 when one is detected. Use of
+ `-mno-check-zero-division' suppresses such checking for code
+ generated to run on an MC88100 processor.
+
+ GCC assumes that the MC88110 processor correctly detects all
+ instances of integer division by zero. When `-m88110' is
+ specified, no explicit checks for zero-valued divisors are
+ generated, and both `-mcheck-zero-division' and
+ `-mno-check-zero-division' are ignored.
+
+`-muse-div-instruction'
+ Use the div instruction for signed integer division on the MC88100
+ processor. By default, the div instruction is not used.
+
+ On the MC88100 processor the signed integer division instruction
+ div) traps to the operating system on a negative operand. The
+ operating system transparently completes the operation, but at a
+ large cost in execution time. By default, when compiling code
+ that might be run on an MC88100 processor, GCC emulates signed
+ integer division using the unsigned integer division instruction
+ divu), thereby avoiding the large penalty of a trap to the
+ operating system. Such emulation has its own, smaller, execution
+ cost in both time and space. To the extent that your code's
+ important signed integer division operations are performed on two
+ nonnegative operands, it may be desirable to use the div
+ instruction directly.
+
+ On the MC88110 processor the div instruction (also known as the
+ divs instruction) processes negative operands without trapping to
+ the operating system. When `-m88110' is specified,
+ `-muse-div-instruction' is ignored, and the div instruction is used
+ for signed integer division.
+
+ Note that the result of dividing `INT_MIN' by -1 is undefined. In
+ particular, the behavior of such a division with and without
+ `-muse-div-instruction' may differ.
+
+`-mtrap-large-shift'
+`-mhandle-large-shift'
+ Include code to detect bit-shifts of more than 31 bits;
+ respectively, trap such shifts or emit code to handle them
+ properly. By default GCC makes no special provision for large bit
+ shifts.
+
+`-mwarn-passed-structs'
+ Warn when a function passes a struct as an argument or result.
+ Structure-passing conventions have changed during the evolution of
+ the C language, and are often the source of portability problems.
+ By default, GCC issues no such warning.
+
+\1f
+File: gcc.info, Node: RS/6000 and PowerPC Options, Next: RT Options, Prev: M88K Options, Up: Submodel Options
+
+3.17.12 IBM RS/6000 and PowerPC Options
+---------------------------------------
+
+These `-m' options are defined for the IBM RS/6000 and PowerPC:
+`-mpower'
+`-mno-power'
+`-mpower2'
+`-mno-power2'
+`-mpowerpc'
+`-mno-powerpc'
+`-mpowerpc-gpopt'
+`-mno-powerpc-gpopt'
+`-mpowerpc-gfxopt'
+`-mno-powerpc-gfxopt'
+`-mpowerpc64'
+`-mno-powerpc64'
+ GCC supports two related instruction set architectures for the
+ RS/6000 and PowerPC. The "POWER" instruction set are those
+ instructions supported by the `rios' chip set used in the original
+ RS/6000 systems and the "PowerPC" instruction set is the
+ architecture of the Motorola MPC5xx, MPC6xx, MPC8xx
+ microprocessors, and the IBM 4xx microprocessors.
+
+ Neither architecture is a subset of the other. However there is a
+ large common subset of instructions supported by both. An MQ
+ register is included in processors supporting the POWER
+ architecture.
+
+ You use these options to specify which instructions are available
+ on the processor you are using. The default value of these
+ options is determined when configuring GCC. Specifying the
+ `-mcpu=CPU_TYPE' overrides the specification of these options. We
+ recommend you use the `-mcpu=CPU_TYPE' option rather than the
+ options listed above.
+
+ The `-mpower' option allows GCC to generate instructions that are
+ found only in the POWER architecture and to use the MQ register.
+ Specifying `-mpower2' implies `-power' and also allows GCC to
+ generate instructions that are present in the POWER2 architecture
+ but not the original POWER architecture.
+
+ The `-mpowerpc' option allows GCC to generate instructions that
+ are found only in the 32-bit subset of the PowerPC architecture.
+ Specifying `-mpowerpc-gpopt' implies `-mpowerpc' and also allows
+ GCC to use the optional PowerPC architecture instructions in the
+ General Purpose group, including floating-point square root.
+ Specifying `-mpowerpc-gfxopt' implies `-mpowerpc' and also allows
+ GCC to use the optional PowerPC architecture instructions in the
+ Graphics group, including floating-point select.
+
+ The `-mpowerpc64' option allows GCC to generate the additional
+ 64-bit instructions that are found in the full PowerPC64
+ architecture and to treat GPRs as 64-bit, doubleword quantities.
+ GCC defaults to `-mno-powerpc64'.
+
+ If you specify both `-mno-power' and `-mno-powerpc', GCC will use
+ only the instructions in the common subset of both architectures
+ plus some special AIX common-mode calls, and will not use the MQ
+ register. Specifying both `-mpower' and `-mpowerpc' permits GCC
+ to use any instruction from either architecture and to allow use
+ of the MQ register; specify this for the Motorola MPC601.
+
+`-mnew-mnemonics'
+`-mold-mnemonics'
+ Select which mnemonics to use in the generated assembler code.
+ With `-mnew-mnemonics', GCC uses the assembler mnemonics defined
+ for the PowerPC architecture. With `-mold-mnemonics' it uses the
+ assembler mnemonics defined for the POWER architecture.
+ Instructions defined in only one architecture have only one
+ mnemonic; GCC uses that mnemonic irrespective of which of these
+ options is specified.
+
+ GCC defaults to the mnemonics appropriate for the architecture in
+ use. Specifying `-mcpu=CPU_TYPE' sometimes overrides the value of
+ these option. Unless you are building a cross-compiler, you
+ should normally not specify either `-mnew-mnemonics' or
+ `-mold-mnemonics', but should instead accept the default.
+
+`-mcpu=CPU_TYPE'
+ Set architecture type, register usage, choice of mnemonics, and
+ instruction scheduling parameters for machine type CPU_TYPE.
+ Supported values for CPU_TYPE are `rios', `rios1', `rsc', `rios2',
+ `rs64a', `601', `602', `603', `603e', `604', `604e', `620', `630',
+ `740', `7400', `7450', `750', `power', `power2', `powerpc', `403',
+ `505', `801', `821', `823', and `860' and `common'.
+
+ `-mcpu=common' selects a completely generic processor. Code
+ generated under this option will run on any POWER or PowerPC
+ processor. GCC will use only the instructions in the common
+ subset of both architectures, and will not use the MQ register.
+ GCC assumes a generic processor model for scheduling purposes.
+
+ `-mcpu=power', `-mcpu=power2', `-mcpu=powerpc', and
+ `-mcpu=powerpc64' specify generic POWER, POWER2, pure 32-bit
+ PowerPC (i.e., not MPC601), and 64-bit PowerPC architecture machine
+ types, with an appropriate, generic processor model assumed for
+ scheduling purposes.
+
+ The other options specify a specific processor. Code generated
+ under those options will run best on that processor, and may not
+ run at all on others.
+
+ The `-mcpu' options automatically enable or disable other `-m'
+ options as follows:
+
+ `common'
+ `-mno-power', `-mno-powerc'
+
+ `power'
+ `power2'
+ `rios1'
+ `rios2'
+ `rsc'
+ `-mpower', `-mno-powerpc', `-mno-new-mnemonics'
+
+ `powerpc'
+ `rs64a'
+ `602'
+ `603'
+ `603e'
+ `604'
+ `620'
+ `630'
+ `740'
+ `7400'
+ `7450'
+ `750'
+ `505'
+ `-mno-power', `-mpowerpc', `-mnew-mnemonics'
+
+ `601'
+ `-mpower', `-mpowerpc', `-mnew-mnemonics'
+
+ `403'
+ `821'
+ `860'
+ `-mno-power', `-mpowerpc', `-mnew-mnemonics', `-msoft-float'
+
+`-mtune=CPU_TYPE'
+ Set the instruction scheduling parameters for machine type
+ CPU_TYPE, but do not set the architecture type, register usage, or
+ choice of mnemonics, as `-mcpu=CPU_TYPE' would. The same values
+ for CPU_TYPE are used for `-mtune' as for `-mcpu'. If both are
+ specified, the code generated will use the architecture,
+ registers, and mnemonics set by `-mcpu', but the scheduling
+ parameters set by `-mtune'.
+
+`-maltivec'
+`-mno-altivec'
+ These switches enable or disable the use of built-in functions that
+ allow access to the AltiVec instruction set. You may also need to
+ set `-mabi=altivec' to adjust the current ABI with AltiVec ABI
+ enhancements.
+
+`-mfull-toc'
+`-mno-fp-in-toc'
+`-mno-sum-in-toc'
+`-mminimal-toc'
+ Modify generation of the TOC (Table Of Contents), which is created
+ for every executable file. The `-mfull-toc' option is selected by
+ default. In that case, GCC will allocate at least one TOC entry
+ for each unique non-automatic variable reference in your program.
+ GCC will also place floating-point constants in the TOC. However,
+ only 16,384 entries are available in the TOC.
+
+ If you receive a linker error message that saying you have
+ overflowed the available TOC space, you can reduce the amount of
+ TOC space used with the `-mno-fp-in-toc' and `-mno-sum-in-toc'
+ options. `-mno-fp-in-toc' prevents GCC from putting floating-point
+ constants in the TOC and `-mno-sum-in-toc' forces GCC to generate
+ code to calculate the sum of an address and a constant at run-time
+ instead of putting that sum into the TOC. You may specify one or
+ both of these options. Each causes GCC to produce very slightly
+ slower and larger code at the expense of conserving TOC space.
+
+ If you still run out of space in the TOC even when you specify
+ both of these options, specify `-mminimal-toc' instead. This
+ option causes GCC to make only one TOC entry for every file. When
+ you specify this option, GCC will produce code that is slower and
+ larger but which uses extremely little TOC space. You may wish to
+ use this option only on files that contain less frequently
+ executed code.
+
+`-maix64'
+`-maix32'
+ Enable 64-bit AIX ABI and calling convention: 64-bit pointers,
+ 64-bit `long' type, and the infrastructure needed to support them.
+ Specifying `-maix64' implies `-mpowerpc64' and `-mpowerpc', while
+ `-maix32' disables the 64-bit ABI and implies `-mno-powerpc64'.
+ GCC defaults to `-maix32'.
+
+`-mxl-call'
+`-mno-xl-call'
+ On AIX, pass floating-point arguments to prototyped functions
+ beyond the register save area (RSA) on the stack in addition to
+ argument FPRs. The AIX calling convention was extended but not
+ initially documented to handle an obscure K&R C case of calling a
+ function that takes the address of its arguments with fewer
+ arguments than declared. AIX XL compilers access floating point
+ arguments which do not fit in the RSA from the stack when a
+ subroutine is compiled without optimization. Because always
+ storing floating-point arguments on the stack is inefficient and
+ rarely needed, this option is not enabled by default and only is
+ necessary when calling subroutines compiled by AIX XL compilers
+ without optimization.
+
+`-mpe'
+ Support "IBM RS/6000 SP" "Parallel Environment" (PE). Link an
+ application written to use message passing with special startup
+ code to enable the application to run. The system must have PE
+ installed in the standard location (`/usr/lpp/ppe.poe/'), or the
+ `specs' file must be overridden with the `-specs=' option to
+ specify the appropriate directory location. The Parallel
+ Environment does not support threads, so the `-mpe' option and the
+ `-pthread' option are incompatible.
+
+`-msoft-float'
+`-mhard-float'
+ Generate code that does not use (uses) the floating-point register
+ set. Software floating point emulation is provided if you use the
+ `-msoft-float' option, and pass the option to GCC when linking.
+
+`-mmultiple'
+`-mno-multiple'
+ Generate code that uses (does not use) the load multiple word
+ instructions and the store multiple word instructions. These
+ instructions are generated by default on POWER systems, and not
+ generated on PowerPC systems. Do not use `-mmultiple' on little
+ endian PowerPC systems, since those instructions do not work when
+ the processor is in little endian mode. The exceptions are PPC740
+ and PPC750 which permit the instructions usage in little endian
+ mode.
+
+`-mstring'
+`-mno-string'
+ Generate code that uses (does not use) the load string instructions
+ and the store string word instructions to save multiple registers
+ and do small block moves. These instructions are generated by
+ default on POWER systems, and not generated on PowerPC systems.
+ Do not use `-mstring' on little endian PowerPC systems, since those
+ instructions do not work when the processor is in little endian
+ mode. The exceptions are PPC740 and PPC750 which permit the
+ instructions usage in little endian mode.
+
+`-mupdate'
+`-mno-update'
+ Generate code that uses (does not use) the load or store
+ instructions that update the base register to the address of the
+ calculated memory location. These instructions are generated by
+ default. If you use `-mno-update', there is a small window
+ between the time that the stack pointer is updated and the address
+ of the previous frame is stored, which means code that walks the
+ stack frame across interrupts or signals may get corrupted data.
+
+`-mfused-madd'
+`-mno-fused-madd'
+ Generate code that uses (does not use) the floating point multiply
+ and accumulate instructions. These instructions are generated by
+ default if hardware floating is used.
+
+`-mno-bit-align'
+`-mbit-align'
+ On System V.4 and embedded PowerPC systems do not (do) force
+ structures and unions that contain bit-fields to be aligned to the
+ base type of the bit-field.
+
+ For example, by default a structure containing nothing but 8
+ `unsigned' bit-fields of length 1 would be aligned to a 4 byte
+ boundary and have a size of 4 bytes. By using `-mno-bit-align',
+ the structure would be aligned to a 1 byte boundary and be one
+ byte in size.
+
+`-mno-strict-align'
+`-mstrict-align'
+ On System V.4 and embedded PowerPC systems do not (do) assume that
+ unaligned memory references will be handled by the system.
+
+`-mrelocatable'
+`-mno-relocatable'
+ On embedded PowerPC systems generate code that allows (does not
+ allow) the program to be relocated to a different address at
+ runtime. If you use `-mrelocatable' on any module, all objects
+ linked together must be compiled with `-mrelocatable' or
+ `-mrelocatable-lib'.
+
+`-mrelocatable-lib'
+`-mno-relocatable-lib'
+ On embedded PowerPC systems generate code that allows (does not
+ allow) the program to be relocated to a different address at
+ runtime. Modules compiled with `-mrelocatable-lib' can be linked
+ with either modules compiled without `-mrelocatable' and
+ `-mrelocatable-lib' or with modules compiled with the
+ `-mrelocatable' options.
+
+`-mno-toc'
+`-mtoc'
+ On System V.4 and embedded PowerPC systems do not (do) assume that
+ register 2 contains a pointer to a global area pointing to the
+ addresses used in the program.
+
+`-mlittle'
+`-mlittle-endian'
+ On System V.4 and embedded PowerPC systems compile code for the
+ processor in little endian mode. The `-mlittle-endian' option is
+ the same as `-mlittle'.
+
+`-mbig'
+`-mbig-endian'
+ On System V.4 and embedded PowerPC systems compile code for the
+ processor in big endian mode. The `-mbig-endian' option is the
+ same as `-mbig'.
+
+`-mcall-sysv'
+ On System V.4 and embedded PowerPC systems compile code using
+ calling conventions that adheres to the March 1995 draft of the
+ System V Application Binary Interface, PowerPC processor
+ supplement. This is the default unless you configured GCC using
+ `powerpc-*-eabiaix'.
+
+`-mcall-sysv-eabi'
+ Specify both `-mcall-sysv' and `-meabi' options.
+
+`-mcall-sysv-noeabi'
+ Specify both `-mcall-sysv' and `-mno-eabi' options.
+
+`-mcall-aix'
+ On System V.4 and embedded PowerPC systems compile code using
+ calling conventions that are similar to those used on AIX. This
+ is the default if you configured GCC using `powerpc-*-eabiaix'.
+
+`-mcall-solaris'
+ On System V.4 and embedded PowerPC systems compile code for the
+ Solaris operating system.
+
+`-mcall-linux'
+ On System V.4 and embedded PowerPC systems compile code for the
+ Linux-based GNU system.
+
+`-mcall-gnu'
+ On System V.4 and embedded PowerPC systems compile code for the
+ Hurd-based GNU system.
+
+`-mcall-netbsd'
+ On System V.4 and embedded PowerPC systems compile code for the
+ NetBSD operating system.
+
+`-maix-struct-return'
+ Return all structures in memory (as specified by the AIX ABI).
+
+`-msvr4-struct-return'
+ Return structures smaller than 8 bytes in registers (as specified
+ by the SVR4 ABI).
+
+`-mabi=altivec'
+ Extend the current ABI with AltiVec ABI extensions. This does not
+ change the default ABI, instead it adds the AltiVec ABI extensions
+ to the current ABI.
+
+`-mabi=no-altivec'
+ Disable AltiVec ABI extensions for the current ABI.
+
+`-mprototype'
+`-mno-prototype'
+ On System V.4 and embedded PowerPC systems assume that all calls to
+ variable argument functions are properly prototyped. Otherwise,
+ the compiler must insert an instruction before every non
+ prototyped call to set or clear bit 6 of the condition code
+ register (CR) to indicate whether floating point values were
+ passed in the floating point registers in case the function takes
+ a variable arguments. With `-mprototype', only calls to
+ prototyped variable argument functions will set or clear the bit.
+
+`-msim'
+ On embedded PowerPC systems, assume that the startup module is
+ called `sim-crt0.o' and that the standard C libraries are
+ `libsim.a' and `libc.a'. This is the default for
+ `powerpc-*-eabisim'. configurations.
+
+`-mmvme'
+ On embedded PowerPC systems, assume that the startup module is
+ called `crt0.o' and the standard C libraries are `libmvme.a' and
+ `libc.a'.
+
+`-mads'
+ On embedded PowerPC systems, assume that the startup module is
+ called `crt0.o' and the standard C libraries are `libads.a' and
+ `libc.a'.
+
+`-myellowknife'
+ On embedded PowerPC systems, assume that the startup module is
+ called `crt0.o' and the standard C libraries are `libyk.a' and
+ `libc.a'.
+
+`-mvxworks'
+ On System V.4 and embedded PowerPC systems, specify that you are
+ compiling for a VxWorks system.
+
+`-memb'
+ On embedded PowerPC systems, set the PPC_EMB bit in the ELF flags
+ header to indicate that `eabi' extended relocations are used.
+
+`-meabi'
+`-mno-eabi'
+ On System V.4 and embedded PowerPC systems do (do not) adhere to
+ the Embedded Applications Binary Interface (eabi) which is a set of
+ modifications to the System V.4 specifications. Selecting `-meabi'
+ means that the stack is aligned to an 8 byte boundary, a function
+ `__eabi' is called to from `main' to set up the eabi environment,
+ and the `-msdata' option can use both `r2' and `r13' to point to
+ two separate small data areas. Selecting `-mno-eabi' means that
+ the stack is aligned to a 16 byte boundary, do not call an
+ initialization function from `main', and the `-msdata' option will
+ only use `r13' to point to a single small data area. The `-meabi'
+ option is on by default if you configured GCC using one of the
+ `powerpc*-*-eabi*' options.
+
+`-msdata=eabi'
+ On System V.4 and embedded PowerPC systems, put small initialized
+ `const' global and static data in the `.sdata2' section, which is
+ pointed to by register `r2'. Put small initialized non-`const'
+ global and static data in the `.sdata' section, which is pointed
+ to by register `r13'. Put small uninitialized global and static
+ data in the `.sbss' section, which is adjacent to the `.sdata'
+ section. The `-msdata=eabi' option is incompatible with the
+ `-mrelocatable' option. The `-msdata=eabi' option also sets the
+ `-memb' option.
+
+`-msdata=sysv'
+ On System V.4 and embedded PowerPC systems, put small global and
+ static data in the `.sdata' section, which is pointed to by
+ register `r13'. Put small uninitialized global and static data in
+ the `.sbss' section, which is adjacent to the `.sdata' section.
+ The `-msdata=sysv' option is incompatible with the `-mrelocatable'
+ option.
+
+`-msdata=default'
+`-msdata'
+ On System V.4 and embedded PowerPC systems, if `-meabi' is used,
+ compile code the same as `-msdata=eabi', otherwise compile code the
+ same as `-msdata=sysv'.
+
+`-msdata-data'
+ On System V.4 and embedded PowerPC systems, put small global and
+ static data in the `.sdata' section. Put small uninitialized
+ global and static data in the `.sbss' section. Do not use
+ register `r13' to address small data however. This is the default
+ behavior unless other `-msdata' options are used.
+
+`-msdata=none'
+`-mno-sdata'
+ On embedded PowerPC systems, put all initialized global and static
+ data in the `.data' section, and all uninitialized data in the
+ `.bss' section.
+
+`-G NUM'
+ On embedded PowerPC systems, put global and static items less than
+ or equal to NUM bytes into the small data or bss sections instead
+ of the normal data or bss section. By default, NUM is 8. The `-G
+ NUM' switch is also passed to the linker. All modules should be
+ compiled with the same `-G NUM' value.
+
+`-mregnames'
+`-mno-regnames'
+ On System V.4 and embedded PowerPC systems do (do not) emit
+ register names in the assembly language output using symbolic
+ forms.
+
+`-pthread'
+ Adds support for multithreading with the "pthreads" library. This
+ option sets flags for both the preprocessor and linker.
+
+
+\1f
+File: gcc.info, Node: RT Options, Next: MIPS Options, Prev: RS/6000 and PowerPC Options, Up: Submodel Options
+
+3.17.13 IBM RT Options
+----------------------
+
+These `-m' options are defined for the IBM RT PC:
+
+`-min-line-mul'
+ Use an in-line code sequence for integer multiplies. This is the
+ default.
+
+`-mcall-lib-mul'
+ Call `lmul$$' for integer multiples.
+
+`-mfull-fp-blocks'
+ Generate full-size floating point data blocks, including the
+ minimum amount of scratch space recommended by IBM. This is the
+ default.
+
+`-mminimum-fp-blocks'
+ Do not include extra scratch space in floating point data blocks.
+ This results in smaller code, but slower execution, since scratch
+ space must be allocated dynamically.
+
+`-mfp-arg-in-fpregs'
+ Use a calling sequence incompatible with the IBM calling
+ convention in which floating point arguments are passed in
+ floating point registers. Note that `varargs.h' and `stdarg.h'
+ will not work with floating point operands if this option is
+ specified.
+
+`-mfp-arg-in-gregs'
+ Use the normal calling convention for floating point arguments.
+ This is the default.
+
+`-mhc-struct-return'
+ Return structures of more than one word in memory, rather than in a
+ register. This provides compatibility with the MetaWare HighC (hc)
+ compiler. Use the option `-fpcc-struct-return' for compatibility
+ with the Portable C Compiler (pcc).
+
+`-mnohc-struct-return'
+ Return some structures of more than one word in registers, when
+ convenient. This is the default. For compatibility with the
+ IBM-supplied compilers, use the option `-fpcc-struct-return' or the
+ option `-mhc-struct-return'.
+
+\1f
+File: gcc.info, Node: MIPS Options, Next: i386 and x86-64 Options, Prev: RT Options, Up: Submodel Options
+
+3.17.14 MIPS Options
+--------------------
+
+These `-m' options are defined for the MIPS family of computers:
+
+`-march=CPU-TYPE'
+ Assume the defaults for the machine type CPU-TYPE when generating
+ instructions. The choices for CPU-TYPE are `r2000', `r3000',
+ `r3900', `r4000', `r4100', `r4300', `r4400', `r4600', `r4650',
+ `r5000', `r6000', `r8000', and `orion'. Additionally, the
+ `r2000', `r3000', `r4000', `r5000', and `r6000' can be abbreviated
+ as `r2k' (or `r2K'), `r3k', etc.
+
+`-mtune=CPU-TYPE'
+ Assume the defaults for the machine type CPU-TYPE when scheduling
+ instructions. The choices for CPU-TYPE are `r2000', `r3000',
+ `r3900', `r4000', `r4100', `r4300', `r4400', `r4600', `r4650',
+ `r5000', `r6000', `r8000', and `orion'. Additionally, the
+ `r2000', `r3000', `r4000', `r5000', and `r6000' can be abbreviated
+ as `r2k' (or `r2K'), `r3k', etc. While picking a specific
+ CPU-TYPE will schedule things appropriately for that particular
+ chip, the compiler will not generate any code that does not meet
+ level 1 of the MIPS ISA (instruction set architecture) without a
+ `-mipsX' or `-mabi' switch being used.
+
+`-mcpu=CPU-TYPE'
+ This is identical to specifying both `-march' and `-mtune'.
+
+`-mips1'
+ Issue instructions from level 1 of the MIPS ISA. This is the
+ default. `r3000' is the default CPU-TYPE at this ISA level.
+
+`-mips2'
+ Issue instructions from level 2 of the MIPS ISA (branch likely,
+ square root instructions). `r6000' is the default CPU-TYPE at this
+ ISA level.
+
+`-mips3'
+ Issue instructions from level 3 of the MIPS ISA (64-bit
+ instructions). `r4000' is the default CPU-TYPE at this ISA level.
+
+`-mips4'
+ Issue instructions from level 4 of the MIPS ISA (conditional move,
+ prefetch, enhanced FPU instructions). `r8000' is the default
+ CPU-TYPE at this ISA level.
+
+`-mfp32'
+ Assume that 32 32-bit floating point registers are available.
+ This is the default.
+
+`-mfp64'
+ Assume that 32 64-bit floating point registers are available.
+ This is the default when the `-mips3' option is used.
+
+`-mfused-madd'
+`-mno-fused-madd'
+ Generate code that uses (does not use) the floating point multiply
+ and accumulate instructions, when they are available. These
+ instructions are generated by default if they are available, but
+ this may be undesirable if the extra precision causes problems or
+ on certain chips in the mode where denormals are rounded to zero
+ where denormals generated by multiply and accumulate instructions
+ cause exceptions anyway.
+
+`-mgp32'
+ Assume that 32 32-bit general purpose registers are available.
+ This is the default.
+
+`-mgp64'
+ Assume that 32 64-bit general purpose registers are available.
+ This is the default when the `-mips3' option is used.
+
+`-mint64'
+ Force int and long types to be 64 bits wide. See `-mlong32' for an
+ explanation of the default, and the width of pointers.
+
+`-mlong64'
+ Force long types to be 64 bits wide. See `-mlong32' for an
+ explanation of the default, and the width of pointers.
+
+`-mlong32'
+ Force long, int, and pointer types to be 32 bits wide.
+
+ If none of `-mlong32', `-mlong64', or `-mint64' are set, the size
+ of ints, longs, and pointers depends on the ABI and ISA chosen.
+ For `-mabi=32', and `-mabi=n32', ints and longs are 32 bits wide.
+ For `-mabi=64', ints are 32 bits, and longs are 64 bits wide. For
+ `-mabi=eabi' and either `-mips1' or `-mips2', ints and longs are
+ 32 bits wide. For `-mabi=eabi' and higher ISAs, ints are 32 bits,
+ and longs are 64 bits wide. The width of pointer types is the
+ smaller of the width of longs or the width of general purpose
+ registers (which in turn depends on the ISA).
+
+`-mabi=32'
+`-mabi=o64'
+`-mabi=n32'
+`-mabi=64'
+`-mabi=eabi'
+ Generate code for the indicated ABI. The default instruction
+ level is `-mips1' for `32', `-mips3' for `n32', and `-mips4'
+ otherwise. Conversely, with `-mips1' or `-mips2', the default ABI
+ is `32'; otherwise, the default ABI is `64'.
+
+`-mmips-as'
+ Generate code for the MIPS assembler, and invoke `mips-tfile' to
+ add normal debug information. This is the default for all
+ platforms except for the OSF/1 reference platform, using the
+ OSF/rose object format. If the either of the `-gstabs' or
+ `-gstabs+' switches are used, the `mips-tfile' program will
+ encapsulate the stabs within MIPS ECOFF.
+
+`-mgas'
+ Generate code for the GNU assembler. This is the default on the
+ OSF/1 reference platform, using the OSF/rose object format. Also,
+ this is the default if the configure option `--with-gnu-as' is
+ used.
+
+`-msplit-addresses'
+`-mno-split-addresses'
+ Generate code to load the high and low parts of address constants
+ separately. This allows GCC to optimize away redundant loads of
+ the high order bits of addresses. This optimization requires GNU
+ as and GNU ld. This optimization is enabled by default for some
+ embedded targets where GNU as and GNU ld are standard.
+
+`-mrnames'
+`-mno-rnames'
+ The `-mrnames' switch says to output code using the MIPS software
+ names for the registers, instead of the hardware names (ie, A0
+ instead of $4). The only known assembler that supports this option
+ is the Algorithmics assembler.
+
+`-mgpopt'
+`-mno-gpopt'
+ The `-mgpopt' switch says to write all of the data declarations
+ before the instructions in the text section, this allows the MIPS
+ assembler to generate one word memory references instead of using
+ two words for short global or static data items. This is on by
+ default if optimization is selected.
+
+`-mstats'
+`-mno-stats'
+ For each non-inline function processed, the `-mstats' switch
+ causes the compiler to emit one line to the standard error file to
+ print statistics about the program (number of registers saved,
+ stack size, etc.).
+
+`-mmemcpy'
+`-mno-memcpy'
+ The `-mmemcpy' switch makes all block moves call the appropriate
+ string function (`memcpy' or `bcopy') instead of possibly
+ generating inline code.
+
+`-mmips-tfile'
+`-mno-mips-tfile'
+ The `-mno-mips-tfile' switch causes the compiler not postprocess
+ the object file with the `mips-tfile' program, after the MIPS
+ assembler has generated it to add debug support. If `mips-tfile'
+ is not run, then no local variables will be available to the
+ debugger. In addition, `stage2' and `stage3' objects will have
+ the temporary file names passed to the assembler embedded in the
+ object file, which means the objects will not compare the same.
+ The `-mno-mips-tfile' switch should only be used when there are
+ bugs in the `mips-tfile' program that prevents compilation.
+
+`-msoft-float'
+ Generate output containing library calls for floating point.
+ *Warning:* the requisite libraries are not part of GCC. Normally
+ the facilities of the machine's usual C compiler are used, but
+ this can't be done directly in cross-compilation. You must make
+ your own arrangements to provide suitable library functions for
+ cross-compilation.
+
+`-mhard-float'
+ Generate output containing floating point instructions. This is
+ the default if you use the unmodified sources.
+
+`-mabicalls'
+`-mno-abicalls'
+ Emit (or do not emit) the pseudo operations `.abicalls',
+ `.cpload', and `.cprestore' that some System V.4 ports use for
+ position independent code.
+
+`-mlong-calls'
+`-mno-long-calls'
+ Do all calls with the `JALR' instruction, which requires loading
+ up a function's address into a register before the call. You need
+ to use this switch, if you call outside of the current 512
+ megabyte segment to functions that are not through pointers.
+
+`-mhalf-pic'
+`-mno-half-pic'
+ Put pointers to extern references into the data section and load
+ them up, rather than put the references in the text section.
+
+`-membedded-pic'
+`-mno-embedded-pic'
+ Generate PIC code suitable for some embedded systems. All calls
+ are made using PC relative address, and all data is addressed
+ using the $gp register. No more than 65536 bytes of global data
+ may be used. This requires GNU as and GNU ld which do most of the
+ work. This currently only works on targets which use ECOFF; it
+ does not work with ELF.
+
+`-membedded-data'
+`-mno-embedded-data'
+ Allocate variables to the read-only data section first if
+ possible, then next in the small data section if possible,
+ otherwise in data. This gives slightly slower code than the
+ default, but reduces the amount of RAM required when executing,
+ and thus may be preferred for some embedded systems.
+
+`-muninit-const-in-rodata'
+`-mno-uninit-const-in-rodata'
+ When used together with `-membedded-data', it will always store
+ uninitialized const variables in the read-only data section.
+
+`-msingle-float'
+`-mdouble-float'
+ The `-msingle-float' switch tells gcc to assume that the floating
+ point coprocessor only supports single precision operations, as on
+ the `r4650' chip. The `-mdouble-float' switch permits gcc to use
+ double precision operations. This is the default.
+
+`-mmad'
+`-mno-mad'
+ Permit use of the `mad', `madu' and `mul' instructions, as on the
+ `r4650' chip.
+
+`-m4650'
+ Turns on `-msingle-float', `-mmad', and, at least for now,
+ `-mcpu=r4650'.
+
+`-mips16'
+`-mno-mips16'
+ Enable 16-bit instructions.
+
+`-mentry'
+ Use the entry and exit pseudo ops. This option can only be used
+ with `-mips16'.
+
+`-EL'
+ Compile code for the processor in little endian mode. The
+ requisite libraries are assumed to exist.
+
+`-EB'
+ Compile code for the processor in big endian mode. The requisite
+ libraries are assumed to exist.
+
+`-G NUM'
+ Put global and static items less than or equal to NUM bytes into
+ the small data or bss sections instead of the normal data or bss
+ section. This allows the assembler to emit one word memory
+ reference instructions based on the global pointer (GP or $28),
+ instead of the normal two words used. By default, NUM is 8 when
+ the MIPS assembler is used, and 0 when the GNU assembler is used.
+ The `-G NUM' switch is also passed to the assembler and linker.
+ All modules should be compiled with the same `-G NUM' value.
+
+`-nocpp'
+ Tell the MIPS assembler to not run its preprocessor over user
+ assembler files (with a `.s' suffix) when assembling them.
+
+`-mfix7000'
+ Pass an option to gas which will cause nops to be inserted if the
+ read of the destination register of an mfhi or mflo instruction
+ occurs in the following two instructions.
+
+`-no-crt0'
+ Do not include the default crt0.
+
+`-mflush-func=FUNC'
+`-mno-flush-func'
+ Specifies the function to call to flush the I and D caches, or to
+ not call any such function. If called, the function must take the
+ same arguments as the common `_flush_func()', that is, the address
+ of the memory range for which the cache is being flushed, the size
+ of the memory range, and the number 3 (to flush both caches). The
+ default depends on the target gcc was configured for, but commonly
+ is either `_flush_func' or `__cpu_flush'.
+
+ These options are defined by the macro `TARGET_SWITCHES' in the
+machine description. The default for the options is also defined by
+that macro, which enables you to change the defaults.
+
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Code Gen Options, Next: Environment Variables, Prev: Submodel Options, Up: Invoking GCC
-
-Options for Code Generation Conventions
-=======================================
-
- These machine-independent options control the interface conventions
-used in code generation.
-
- Most of them have both positive and negative forms; the negative form
-of `-ffoo' would be `-fno-foo'. In the table below, only one of the
-forms is listed--the one which is not the default. You can figure out
-the other form by either removing `no-' or adding it.
-
-`-fexceptions'
- Enable exception handling. Generates extra code needed to
- propagate exceptions. For some targets, this implies GCC will
- generate frame unwind information for all functions, which can
- produce significant data size overhead, although it does not
- affect execution. If you do not specify this option, GCC will
- enable it by default for languages like C++ which normally require
- exception handling, and disable it for languages like C that do
- not normally require it. However, you may need to enable this
- option when compiling C code that needs to interoperate properly
- with exception handlers written in C++. You may also wish to
- disable this option if you are compiling older C++ programs that
- don't use exception handling.
-
-`-fnon-call-exceptions'
- Generate code that allows trapping instructions to throw
- exceptions. Note that this requires platform-specific runtime
- support that does not exist everywhere. Moreover, it only allows
- _trapping_ instructions to throw exceptions, i.e. memory
- references or floating point instructions. It does not allow
- exceptions to be thrown from arbitrary signal handlers such as
- `SIGALRM'.
-
-`-funwind-tables'
- Similar to `-fexceptions', except that it will just generate any
- needed static data, but will not affect the generated code in any
- other way. You will normally not enable this option; instead, a
- language processor that needs this handling would enable it on
- your behalf.
-
-`-fasynchronous-unwind-tables'
- Generate unwind table in dwarf2 format, if supported by target
- machine. The table is exact at each instruction boundary, so it
- can be used for stack unwinding from asynchronous events (such as
- debugger or garbage collector).
-
-`-fpcc-struct-return'
- Return "short" `struct' and `union' values in memory like longer
- ones, rather than in registers. This convention is less
- efficient, but it has the advantage of allowing intercallability
- between GCC-compiled files and files compiled with other
- compilers, particularly the Portable C Compiler (pcc).
-
- The precise convention for returning structures in memory depends
- on the target configuration macros.
-
- Short structures and unions are those whose size and alignment
- match that of some integer type.
-
- *Warning:* code compiled with the `-fpcc-struct-return' switch is
- not binary compatible with code compiled with the
- `-freg-struct-return' switch. Use it to conform to a non-default
- application binary interface.
-
-`-freg-struct-return'
- Return `struct' and `union' values in registers when possible.
- This is more efficient for small structures than
- `-fpcc-struct-return'.
-
- If you specify neither `-fpcc-struct-return' nor
- `-freg-struct-return', GCC defaults to whichever convention is
- standard for the target. If there is no standard convention, GCC
- defaults to `-fpcc-struct-return', except on targets where GCC is
- the principal compiler. In those cases, we can choose the
- standard, and we chose the more efficient register return
- alternative.
-
- *Warning:* code compiled with the `-freg-struct-return' switch is
- not binary compatible with code compiled with the
- `-fpcc-struct-return' switch. Use it to conform to a non-default
- application binary interface.
-
-`-fshort-enums'
- Allocate to an `enum' type only as many bytes as it needs for the
- declared range of possible values. Specifically, the `enum' type
- will be equivalent to the smallest integer type which has enough
- room.
-
- *Warning:* the `-fshort-enums' switch causes GCC to generate code
- that is not binary compatible with code generated without that
- switch. Use it to conform to a non-default application binary
- interface.
-
-`-fshort-double'
- Use the same size for `double' as for `float'.
-
- *Warning:* the `-fshort-double' switch causes GCC to generate code
- that is not binary compatible with code generated without that
- switch. Use it to conform to a non-default application binary
- interface.
-
-`-fshort-wchar'
- Override the underlying type for `wchar_t' to be `short unsigned
- int' instead of the default for the target. This option is useful
- for building programs to run under WINE.
-
- *Warning:* the `-fshort-wchar' switch causes GCC to generate code
- that is not binary compatible with code generated without that
- switch. Use it to conform to a non-default application binary
- interface.
-
-`-fshared-data'
- Requests that the data and non-`const' variables of this
- compilation be shared data rather than private data. The
- distinction makes sense only on certain operating systems, where
- shared data is shared between processes running the same program,
- while private data exists in one copy per process.
-
-`-fno-common'
- In C, allocate even uninitialized global variables in the data
- section of the object file, rather than generating them as common
- blocks. This has the effect that if the same variable is declared
- (without `extern') in two different compilations, you will get an
- error when you link them. The only reason this might be useful is
- if you wish to verify that the program will work on other systems
- which always work this way.
-
-`-fno-ident'
- Ignore the `#ident' directive.
-
-`-fno-gnu-linker'
- Do not output global initializations (such as C++ constructors and
- destructors) in the form used by the GNU linker (on systems where
- the GNU linker is the standard method of handling them). Use this
- option when you want to use a non-GNU linker, which also requires
- using the `collect2' program to make sure the system linker
- includes constructors and destructors. (`collect2' is included in
- the GCC distribution.) For systems which _must_ use `collect2',
- the compiler driver `gcc' is configured to do this automatically.
-
-`-finhibit-size-directive'
- Don't output a `.size' assembler directive, or anything else that
- would cause trouble if the function is split in the middle, and the
- two halves are placed at locations far apart in memory. This
- option is used when compiling `crtstuff.c'; you should not need to
- use it for anything else.
-
-`-fverbose-asm'
- Put extra commentary information in the generated assembly code to
- make it more readable. This option is generally only of use to
- those who actually need to read the generated assembly code
- (perhaps while debugging the compiler itself).
-
- `-fno-verbose-asm', the default, causes the extra information to
- be omitted and is useful when comparing two assembler files.
-
-`-fvolatile'
- Consider all memory references through pointers to be volatile.
-
-`-fvolatile-global'
- Consider all memory references to extern and global data items to
- be volatile. GCC does not consider static data items to be
- volatile because of this switch.
-
-`-fvolatile-static'
- Consider all memory references to static data to be volatile.
-
-`-fpic'
- Generate position-independent code (PIC) suitable for use in a
- shared library, if supported for the target machine. Such code
- accesses all constant addresses through a global offset table
- (GOT). The dynamic loader resolves the GOT entries when the
- program starts (the dynamic loader is not part of GCC; it is part
- of the operating system). If the GOT size for the linked
- executable exceeds a machine-specific maximum size, you get an
- error message from the linker indicating that `-fpic' does not
- work; in that case, recompile with `-fPIC' instead. (These
- maximums are 16k on the m88k, 8k on the Sparc, and 32k on the m68k
- and RS/6000. The 386 has no such limit.)
-
- Position-independent code requires special support, and therefore
- works only on certain machines. For the 386, GCC supports PIC for
- System V but not for the Sun 386i. Code generated for the IBM
- RS/6000 is always position-independent.
-
-`-fPIC'
- If supported for the target machine, emit position-independent
- code, suitable for dynamic linking and avoiding any limit on the
- size of the global offset table. This option makes a difference
- on the m68k, m88k, and the Sparc.
-
- Position-independent code requires special support, and therefore
- works only on certain machines.
-
-`-ffixed-REG'
- Treat the register named REG as a fixed register; generated code
- should never refer to it (except perhaps as a stack pointer, frame
- pointer or in some other fixed role).
-
- REG must be the name of a register. The register names accepted
- are machine-specific and are defined in the `REGISTER_NAMES' macro
- in the machine description macro file.
-
- This flag does not have a negative form, because it specifies a
- three-way choice.
-
-`-fcall-used-REG'
- Treat the register named REG as an allocable register that is
- clobbered by function calls. It may be allocated for temporaries
- or variables that do not live across a call. Functions compiled
- this way will not save and restore the register REG.
-
- It is an error to used this flag with the frame pointer or stack
- pointer. Use of this flag for other registers that have fixed
- pervasive roles in the machine's execution model will produce
- disastrous results.
-
- This flag does not have a negative form, because it specifies a
- three-way choice.
-
-`-fcall-saved-REG'
- Treat the register named REG as an allocable register saved by
- functions. It may be allocated even for temporaries or variables
- that live across a call. Functions compiled this way will save
- and restore the register REG if they use it.
-
- It is an error to used this flag with the frame pointer or stack
- pointer. Use of this flag for other registers that have fixed
- pervasive roles in the machine's execution model will produce
- disastrous results.
-
- A different sort of disaster will result from the use of this flag
- for a register in which function values may be returned.
-
- This flag does not have a negative form, because it specifies a
- three-way choice.
-
-`-fpack-struct'
- Pack all structure members together without holes.
-
- *Warning:* the `-fpack-struct' switch causes GCC to generate code
- that is not binary compatible with code generated without that
- switch. Additionally, it makes the code suboptimial. Use it to
- conform to a non-default application binary interface.
-
-`-finstrument-functions'
- Generate instrumentation calls for entry and exit to functions.
- Just after function entry and just before function exit, the
- following profiling functions will be called with the address of
- the current function and its call site. (On some platforms,
- `__builtin_return_address' does not work beyond the current
- function, so the call site information may not be available to the
- profiling functions otherwise.)
-
- void __cyg_profile_func_enter (void *this_fn,
- void *call_site);
- void __cyg_profile_func_exit (void *this_fn,
- void *call_site);
-
- The first argument is the address of the start of the current
- function, which may be looked up exactly in the symbol table.
-
- This instrumentation is also done for functions expanded inline in
- other functions. The profiling calls will indicate where,
- conceptually, the inline function is entered and exited. This
- means that addressable versions of such functions must be
- available. If all your uses of a function are expanded inline,
- this may mean an additional expansion of code size. If you use
- `extern inline' in your C code, an addressable version of such
- functions must be provided. (This is normally the case anyways,
- but if you get lucky and the optimizer always expands the
- functions inline, you might have gotten away without providing
- static copies.)
-
- A function may be given the attribute `no_instrument_function', in
- which case this instrumentation will not be done. This can be
- used, for example, for the profiling functions listed above,
- high-priority interrupt routines, and any functions from which the
- profiling functions cannot safely be called (perhaps signal
- handlers, if the profiling routines generate output or allocate
- memory).
-
-`-fstack-check'
- Generate code to verify that you do not go beyond the boundary of
- the stack. You should specify this flag if you are running in an
- environment with multiple threads, but only rarely need to specify
- it in a single-threaded environment since stack overflow is
- automatically detected on nearly all systems if there is only one
- stack.
-
- Note that this switch does not actually cause checking to be done;
- the operating system must do that. The switch causes generation
- of code to ensure that the operating system sees the stack being
- extended.
-
-`-fstack-limit-register=REG'
-`-fstack-limit-symbol=SYM'
-`-fno-stack-limit'
- Generate code to ensure that the stack does not grow beyond a
- certain value, either the value of a register or the address of a
- symbol. If the stack would grow beyond the value, a signal is
- raised. For most targets, the signal is raised before the stack
- overruns the boundary, so it is possible to catch the signal
- without taking special precautions.
-
- For instance, if the stack starts at absolute address `0x80000000'
- and grows downwards, you can use the flags
- `-fstack-limit-symbol=__stack_limit' and
- `-Wl,--defsym,__stack_limit=0x7ffe0000' to enforce a stack limit
- of 128KB. Note that this may only work with the GNU linker.
-
-`-fargument-alias'
-`-fargument-noalias'
-`-fargument-noalias-global'
- Specify the possible relationships among parameters and between
- parameters and global data.
-
- `-fargument-alias' specifies that arguments (parameters) may alias
- each other and may alias global storage.
- `-fargument-noalias' specifies that arguments do not alias each
- other, but may alias global storage.
- `-fargument-noalias-global' specifies that arguments do not alias
- each other and do not alias global storage.
-
- Each language will automatically use whatever option is required by
- the language standard. You should not need to use these options
- yourself.
-
-`-fleading-underscore'
- This option and its counterpart, `-fno-leading-underscore',
- forcibly change the way C symbols are represented in the object
- file. One use is to help link with legacy assembly code.
-
- *Warning:* the `-fleading-underscore' switch causes GCC to
- generate code that is not binary compatible with code generated
- without that switch. Use it to conform to a non-default
- application binary interface. Not all targets provide complete
- support for this switch.
-
-\1f
-File: gcc.info, Node: Environment Variables, Next: Running Protoize, Prev: Code Gen Options, Up: Invoking GCC
-
-Environment Variables Affecting GCC
-===================================
-
- This section describes several environment variables that affect how
-GCC operates. Some of them work by specifying directories or prefixes
-to use when searching for various kinds of files. Some are used to
-specify other aspects of the compilation environment.
-
- Note that you can also specify places to search using options such as
-`-B', `-I' and `-L' (*note Directory Options::). These take precedence
-over places specified using environment variables, which in turn take
-precedence over those specified by the configuration of GCC. *Note
-Controlling the Compilation Driver `gcc': (gccint)Driver.
-
-`LANG'
-`LC_CTYPE'
-`LC_MESSAGES'
-`LC_ALL'
- These environment variables control the way that GCC uses
- localization information that allow GCC to work with different
- national conventions. GCC inspects the locale categories
- `LC_CTYPE' and `LC_MESSAGES' if it has been configured to do so.
- These locale categories can be set to any value supported by your
- installation. A typical value is `en_UK' for English in the United
- Kingdom.
-
- The `LC_CTYPE' environment variable specifies character
- classification. GCC uses it to determine the character boundaries
- in a string; this is needed for some multibyte encodings that
- contain quote and escape characters that would otherwise be
- interpreted as a string end or escape.
-
- The `LC_MESSAGES' environment variable specifies the language to
- use in diagnostic messages.
-
- If the `LC_ALL' environment variable is set, it overrides the value
- of `LC_CTYPE' and `LC_MESSAGES'; otherwise, `LC_CTYPE' and
- `LC_MESSAGES' default to the value of the `LANG' environment
- variable. If none of these variables are set, GCC defaults to
- traditional C English behavior.
-
-`TMPDIR'
- If `TMPDIR' is set, it specifies the directory to use for temporary
- files. GCC uses temporary files to hold the output of one stage of
- compilation which is to be used as input to the next stage: for
- example, the output of the preprocessor, which is the input to the
- compiler proper.
-
-`GCC_EXEC_PREFIX'
- If `GCC_EXEC_PREFIX' is set, it specifies a prefix to use in the
- names of the subprograms executed by the compiler. No slash is
- added when this prefix is combined with the name of a subprogram,
- but you can specify a prefix that ends with a slash if you wish.
-
- If `GCC_EXEC_PREFIX' is not set, GCC will attempt to figure out an
- appropriate prefix to use based on the pathname it was invoked
- with.
-
- If GCC cannot find the subprogram using the specified prefix, it
- tries looking in the usual places for the subprogram.
-
- The default value of `GCC_EXEC_PREFIX' is `PREFIX/lib/gcc-lib/'
- where PREFIX is the value of `prefix' when you ran the `configure'
- script.
-
- Other prefixes specified with `-B' take precedence over this
- prefix.
-
- This prefix is also used for finding files such as `crt0.o' that
- are used for linking.
-
- In addition, the prefix is used in an unusual way in finding the
- directories to search for header files. For each of the standard
- directories whose name normally begins with
- `/usr/local/lib/gcc-lib' (more precisely, with the value of
- `GCC_INCLUDE_DIR'), GCC tries replacing that beginning with the
- specified prefix to produce an alternate directory name. Thus,
- with `-Bfoo/', GCC will search `foo/bar' where it would normally
- search `/usr/local/lib/bar'. These alternate directories are
- searched first; the standard directories come next.
-
-`COMPILER_PATH'
- The value of `COMPILER_PATH' is a colon-separated list of
- directories, much like `PATH'. GCC tries the directories thus
- specified when searching for subprograms, if it can't find the
- subprograms using `GCC_EXEC_PREFIX'.
-
-`LIBRARY_PATH'
- The value of `LIBRARY_PATH' is a colon-separated list of
- directories, much like `PATH'. When configured as a native
- compiler, GCC tries the directories thus specified when searching
- for special linker files, if it can't find them using
- `GCC_EXEC_PREFIX'. Linking using GCC also uses these directories
- when searching for ordinary libraries for the `-l' option (but
- directories specified with `-L' come first).
-
-`LANG'
- This variable is used to pass locale information to the compiler.
- One way in which this information is used is to determine the
- character set to be used when character literals, string literals
- and comments are parsed in C and C++. When the compiler is
- configured to allow multibyte characters, the following values for
- `LANG' are recognized:
-
- `C-JIS'
- Recognize JIS characters.
-
- `C-SJIS'
- Recognize SJIS characters.
-
- `C-EUCJP'
- Recognize EUCJP characters.
-
- If `LANG' is not defined, or if it has some other value, then the
- compiler will use mblen and mbtowc as defined by the default
- locale to recognize and translate multibyte characters.
-
-Some additional environments variables affect the behavior of the
-preprocessor.
-
-`CPATH'
-`C_INCLUDE_PATH'
-`CPLUS_INCLUDE_PATH'
-`OBJC_INCLUDE_PATH'
- Each variable's value is a list of directories separated by a
- special character, much like `PATH', in which to look for header
- files. The special character, `PATH_SEPARATOR', is
- target-dependent and determined at GCC build time. For
- Windows-based targets it is a semicolon, and for almost all other
- targets it is a colon.
-
- `CPATH' specifies a list of directories to be searched as if
- specified with `-I', but after any paths given with `-I' options
- on the command line. The environment variable is used regardless
- of which language is being preprocessed.
-
- The remaining environment variables apply only when preprocessing
- the particular language indicated. Each specifies a list of
- directories to be searched as if specified with `-isystem', but
- after any paths given with `-isystem' options on the command line.
-
-`DEPENDENCIES_OUTPUT'
- If this variable is set, its value specifies how to output
- dependencies for Make based on the non-system header files
- processed by the compiler. System header files are ignored in the
- dependency output.
-
- The value of `DEPENDENCIES_OUTPUT' can be just a file name, in
- which case the Make rules are written to that file, guessing the
- target name from the source file name. Or the value can have the
- form `FILE TARGET', in which case the rules are written to file
- FILE using TARGET as the target name.
-
- In other words, this environment variable is equivalent to
- combining the options `-MM' and `-MF' (*note Preprocessor
- Options::), with an optional `-MT' switch too.
-
-`SUNPRO_DEPENDENCIES'
- This variable is the same as the environment variable
- `DEPENDENCIES_OUTPUT' (*note DEPENDENCIES_OUTPUT::), except that
- system header files are not ignored, so it implies `-M' rather
- than `-MM'. However, the dependence on the main input file is
- omitted. *Note Preprocessor Options::.
-
-\1f
-File: gcc.info, Node: Running Protoize, Prev: Environment Variables, Up: Invoking GCC
-
-Running Protoize
-================
-
- The program `protoize' is an optional part of GCC. You can use it
-to add prototypes to a program, thus converting the program to ISO C in
-one respect. The companion program `unprotoize' does the reverse: it
-removes argument types from any prototypes that are found.
-
- When you run these programs, you must specify a set of source files
-as command line arguments. The conversion programs start out by
-compiling these files to see what functions they define. The
-information gathered about a file FOO is saved in a file named `FOO.X'.
-
- After scanning comes actual conversion. The specified files are all
-eligible to be converted; any files they include (whether sources or
-just headers) are eligible as well.
-
- But not all the eligible files are converted. By default,
-`protoize' and `unprotoize' convert only source and header files in the
-current directory. You can specify additional directories whose files
-should be converted with the `-d DIRECTORY' option. You can also
-specify particular files to exclude with the `-x FILE' option. A file
-is converted if it is eligible, its directory name matches one of the
-specified directory names, and its name within the directory has not
-been excluded.
-
- Basic conversion with `protoize' consists of rewriting most function
-definitions and function declarations to specify the types of the
-arguments. The only ones not rewritten are those for varargs functions.
-
- `protoize' optionally inserts prototype declarations at the
-beginning of the source file, to make them available for any calls that
-precede the function's definition. Or it can insert prototype
-declarations with block scope in the blocks where undeclared functions
-are called.
-
- Basic conversion with `unprotoize' consists of rewriting most
-function declarations to remove any argument types, and rewriting
-function definitions to the old-style pre-ISO form.
-
- Both conversion programs print a warning for any function
-declaration or definition that they can't convert. You can suppress
-these warnings with `-q'.
-
- The output from `protoize' or `unprotoize' replaces the original
-source file. The original file is renamed to a name ending with
-`.save' (for DOS, the saved filename ends in `.sav' without the
-original `.c' suffix). If the `.save' (`.sav' for DOS) file already
-exists, then the source file is simply discarded.
-
- `protoize' and `unprotoize' both depend on GCC itself to scan the
-program and collect information about the functions it uses. So
-neither of these programs will work until GCC is installed.
-
- Here is a table of the options you can use with `protoize' and
-`unprotoize'. Each option works with both programs unless otherwise
-stated.
-
-`-B DIRECTORY'
- Look for the file `SYSCALLS.c.X' in DIRECTORY, instead of the
- usual directory (normally `/usr/local/lib'). This file contains
- prototype information about standard system functions. This option
- applies only to `protoize'.
-
-`-c COMPILATION-OPTIONS'
- Use COMPILATION-OPTIONS as the options when running `gcc' to
- produce the `.X' files. The special option `-aux-info' is always
- passed in addition, to tell `gcc' to write a `.X' file.
-
- Note that the compilation options must be given as a single
- argument to `protoize' or `unprotoize'. If you want to specify
- several `gcc' options, you must quote the entire set of
- compilation options to make them a single word in the shell.
-
- There are certain `gcc' arguments that you cannot use, because they
- would produce the wrong kind of output. These include `-g', `-O',
- `-c', `-S', and `-o' If you include these in the
- COMPILATION-OPTIONS, they are ignored.
-
-`-C'
- Rename files to end in `.C' (`.cc' for DOS-based file systems)
- instead of `.c'. This is convenient if you are converting a C
- program to C++. This option applies only to `protoize'.
-
-`-g'
- Add explicit global declarations. This means inserting explicit
- declarations at the beginning of each source file for each function
- that is called in the file and was not declared. These
- declarations precede the first function definition that contains a
- call to an undeclared function. This option applies only to
- `protoize'.
-
-`-i STRING'
- Indent old-style parameter declarations with the string STRING.
- This option applies only to `protoize'.
-
- `unprotoize' converts prototyped function definitions to old-style
- function definitions, where the arguments are declared between the
- argument list and the initial `{'. By default, `unprotoize' uses
- five spaces as the indentation. If you want to indent with just
- one space instead, use `-i " "'.
-
-`-k'
- Keep the `.X' files. Normally, they are deleted after conversion
- is finished.
-
-`-l'
- Add explicit local declarations. `protoize' with `-l' inserts a
- prototype declaration for each function in each block which calls
- the function without any declaration. This option applies only to
- `protoize'.
-
-`-n'
- Make no real changes. This mode just prints information about the
- conversions that would have been done without `-n'.
-
-`-N'
- Make no `.save' files. The original files are simply deleted.
- Use this option with caution.
-
-`-p PROGRAM'
- Use the program PROGRAM as the compiler. Normally, the name `gcc'
- is used.
-
-`-q'
- Work quietly. Most warnings are suppressed.
-
-`-v'
- Print the version number, just like `-v' for `gcc'.
-
- If you need special compiler options to compile one of your program's
-source files, then you should generate that file's `.X' file specially,
-by running `gcc' on that source file with the appropriate options and
-the option `-aux-info'. Then run `protoize' on the entire set of
-files. `protoize' will use the existing `.X' file because it is newer
-than the source file. For example:
-
- gcc -Dfoo=bar file1.c -aux-info file1.X
- protoize *.c
-
-You need to include the special files along with the rest in the
-`protoize' command, even though their `.X' files already exist, because
-otherwise they won't get converted.
-
- *Note Protoize Caveats::, for more information on how to use
-`protoize' successfully.
-
-\1f
-File: gcc.info, Node: C Implementation, Next: C Extensions, Prev: Invoking GCC, Up: Top
-
-C Implementation-defined behavior
-*********************************
-
- A conforming implementation of ISO C is required to document its
-choice of behavior in each of the areas that are designated
-"implementation defined." The following lists all such areas, along
-with the section number from the ISO/IEC 9899:1999 standard.
-
-* Menu:
-
-* Translation implementation::
-* Environment implementation::
-* Identifiers implementation::
-* Characters implementation::
-* Integers implementation::
-* Floating point implementation::
-* Arrays and pointers implementation::
-* Hints implementation::
-* Structures unions enumerations and bit-fields implementation::
-* Qualifiers implementation::
-* Preprocessing directives implementation::
-* Library functions implementation::
-* Architecture implementation::
-* Locale-specific behavior implementation::
-
-\1f
-File: gcc.info, Node: Translation implementation, Next: Environment implementation, Up: C Implementation
-
-Translation
-===========
-
- * `How a diagnostic is identified (3.10, 5.1.1.3).'
-
- * `Whether each nonempty sequence of white-space characters other
- than new-line is retained or replaced by one space character in
- translation phase 3 (5.1.1.2).'
-
-\1f
-File: gcc.info, Node: Environment implementation, Next: Identifiers implementation, Prev: Translation implementation, Up: C Implementation
-
-Environment
-===========
-
- The behavior of these points are dependent on the implementation of
-the C library, and are not defined by GCC itself.
-
-\1f
-File: gcc.info, Node: Identifiers implementation, Next: Characters implementation, Prev: Environment implementation, Up: C Implementation
-
-Identifiers
-===========
-
- * `Which additional multibyte characters may appear in identifiers
- and their correspondence to universal character names (6.4.2).'
-
- * `The number of significant initial characters in an identifier
- (5.2.4.1, 6.4.2).'
-
-\1f
-File: gcc.info, Node: Characters implementation, Next: Integers implementation, Prev: Identifiers implementation, Up: C Implementation
-
-Characters
-==========
-
- * `The number of bits in a byte (3.6).'
-
- * `The values of the members of the execution character set (5.2.1).'
-
- * `The unique value of the member of the execution character set
- produced for each of the standard alphabetic escape sequences
- (5.2.2).'
-
- * `The value of a `char' object into which has been stored any
- character other than a member of the basic execution character set
- (6.2.5).'
-
- * `Which of `signed char' or `unsigned char' has the same range,
- representation, and behavior as "plain" `char' (6.2.5, 6.3.1.1).'
-
- * `The mapping of members of the source character set (in character
- constants and string literals) to members of the execution
- character set (6.4.4.4, 5.1.1.2).'
-
- * `The value of an integer character constant containing more than
- one character or containing a character or escape sequence that
- does not map to a single-byte execution character (6.4.4.4).'
-
- * `The value of a wide character constant containing more than one
- multibyte character, or containing a multibyte character or escape
- sequence not represented in the extended execution character set
- (6.4.4.4).'
-
- * `The current locale used to convert a wide character constant
- consisting of a single multibyte character that maps to a member
- of the extended execution character set into a corresponding wide
- character code (6.4.4.4).'
-
- * `The current locale used to convert a wide string literal into
- corresponding wide character codes (6.4.5).'
-
- * `The value of a string literal containing a multibyte character or
- escape sequence not represented in the execution character set
- (6.4.5).'
-
-\1f
-File: gcc.info, Node: Integers implementation, Next: Floating point implementation, Prev: Characters implementation, Up: C Implementation
-
-Integers
-========
-
- * `Any extended integer types that exist in the implementation
- (6.2.5).'
-
- * `Whether signed integer types are represented using sign and
- magnitude, two's complement, or one's complement, and whether the
- extraordinary value is a trap representation or an ordinary value
- (6.2.6.2).'
-
- * `The rank of any extended integer type relative to another extended
- integer type with the same precision (6.3.1.1).'
-
- * `The result of, or the signal raised by, converting an integer to a
- signed integer type when the value cannot be represented in an
- object of that type (6.3.1.3).'
-
- * `The results of some bitwise operations on signed integers (6.5).'
-
-\1f
-File: gcc.info, Node: Floating point implementation, Next: Arrays and pointers implementation, Prev: Integers implementation, Up: C Implementation
-
-Floating point
-==============
-
- * `The accuracy of the floating-point operations and of the library
- functions in `<math.h>' and `<complex.h>' that return
- floating-point results (5.2.4.2.2).'
-
- * `The rounding behaviors characterized by non-standard values of
- `FLT_ROUNDS' (5.2.4.2.2).'
-
- * `The evaluation methods characterized by non-standard negative
- values of `FLT_EVAL_METHOD' (5.2.4.2.2).'
-
- * `The direction of rounding when an integer is converted to a
- floating-point number that cannot exactly represent the original
- value (6.3.1.4).'
-
- * `The direction of rounding when a floating-point number is
- converted to a narrower floating-point number (6.3.1.5).'
-
- * `How the nearest representable value or the larger or smaller
- representable value immediately adjacent to the nearest
- representable value is chosen for certain floating constants
- (6.4.4.2).'
-
- * `Whether and how floating expressions are contracted when not
- disallowed by the `FP_CONTRACT' pragma (6.5).'
-
- * `The default state for the `FENV_ACCESS' pragma (7.6.1).'
-
- * `Additional floating-point exceptions, rounding modes,
- environments, and classifications, and their macro names (7.6,
- 7.12).'
-
- * `The default state for the `FP_CONTRACT' pragma (7.12.2).'
-
- * `Whether the "inexact" floating-point exception can be raised when
- the rounded result actually does equal the mathematical result in
- an IEC 60559 conformant implementation (F.9).'
-
- * `Whether the "underflow" (and "inexact") floating-point exception
- can be raised when a result is tiny but not inexact in an IEC
- 60559 conformant implementation (F.9).'
-
-
-\1f
-File: gcc.info, Node: Arrays and pointers implementation, Next: Hints implementation, Prev: Floating point implementation, Up: C Implementation
-
-Arrays and pointers
-===================
-
- * `The result of converting a pointer to an integer or vice versa
- (6.3.2.3).'
-
- A cast from pointer to integer discards most-significant bits if
- the pointer representation is larger than the integer type,
- sign-extends(1) if the pointer representation is smaller than the
- integer type, otherwise the bits are unchanged.
-
- A cast from integer to pointer discards most-significant bits if
- the pointer representation is smaller than the integer type,
- extends according to the signedness of the integer type if the
- pointer representation is larger than the integer type, otherwise
- the bits are unchanged.
-
- When casting from pointer to integer and back again, the resulting
- pointer must reference the same object as the original pointer,
- otherwise the behavior is undefined. That is, one may not use
- integer arithmetic to avoid the undefined behavior of pointer
- arithmetic as proscribed in 6.5.6/8.
-
- * `The size of the result of subtracting two pointers to elements of
- the same array (6.5.6).'
-
-
- ---------- Footnotes ----------
-
- (1) Future versions of GCC may zero-extend, or use a target-defined
-`ptr_extend' pattern. Do not rely on sign extension.
-
-\1f
-File: gcc.info, Node: Hints implementation, Next: Structures unions enumerations and bit-fields implementation, Prev: Arrays and pointers implementation, Up: C Implementation
-
-Hints
-=====
-
- * `The extent to which suggestions made by using the `register'
- storage-class specifier are effective (6.7.1).'
-
- * `The extent to which suggestions made by using the inline function
- specifier are effective (6.7.4).'
-
-
-\1f
-File: gcc.info, Node: Structures unions enumerations and bit-fields implementation, Next: Qualifiers implementation, Prev: Hints implementation, Up: C Implementation
-
-Structures, unions, enumerations, and bit-fields
-================================================
-
- * `Whether a "plain" int bit-field is treated as a `signed int'
- bit-field or as an `unsigned int' bit-field (6.7.2, 6.7.2.1).'
-
- * `Allowable bit-field types other than `_Bool', `signed int', and
- `unsigned int' (6.7.2.1).'
-
- * `Whether a bit-field can straddle a storage-unit boundary
- (6.7.2.1).'
-
- * `The order of allocation of bit-fields within a unit (6.7.2.1).'
-
- * `The alignment of non-bit-field members of structures (6.7.2.1).'
-
- * `The integer type compatible with each enumerated type (6.7.2.2).'
-
-
-\1f
-File: gcc.info, Node: Qualifiers implementation, Next: Preprocessing directives implementation, Prev: Structures unions enumerations and bit-fields implementation, Up: C Implementation
-
-Qualifiers
-==========
-
- * `What constitutes an access to an object that has
- volatile-qualified type (6.7.3).'
-
-
-\1f
-File: gcc.info, Node: Preprocessing directives implementation, Next: Library functions implementation, Prev: Qualifiers implementation, Up: C Implementation
-
-Preprocessing directives
-========================
-
- * `How sequences in both forms of header names are mapped to headers
- or external source file names (6.4.7).'
-
- * `Whether the value of a character constant in a constant expression
- that controls conditional inclusion matches the value of the same
- character constant in the execution character set (6.10.1).'
-
- * `Whether the value of a single-character character constant in a
- constant expression that controls conditional inclusion may have a
- negative value (6.10.1).'
-
- * `The places that are searched for an included `<>' delimited
- header, and how the places are specified or the header is
- identified (6.10.2).'
-
- * `How the named source file is searched for in an included `""'
- delimited header (6.10.2).'
-
- * `The method by which preprocessing tokens (possibly resulting from
- macro expansion) in a `#include' directive are combined into a
- header name (6.10.2).'
-
- * `The nesting limit for `#include' processing (6.10.2).'
-
- * `Whether the `#' operator inserts a `\' character before the `\'
- character that begins a universal character name in a character
- constant or string literal (6.10.3.2).'
-
- * `The behavior on each recognized non-`STDC #pragma' directive
- (6.10.6).'
-
- * `The definitions for `__DATE__' and `__TIME__' when respectively,
- the date and time of translation are not available (6.10.8).'
-
-
-\1f
-File: gcc.info, Node: Library functions implementation, Next: Architecture implementation, Prev: Preprocessing directives implementation, Up: C Implementation
-
-Library functions
-=================
-
- The behavior of these points are dependent on the implementation of
-the C library, and are not defined by GCC itself.
-
-\1f
-File: gcc.info, Node: Architecture implementation, Next: Locale-specific behavior implementation, Prev: Library functions implementation, Up: C Implementation
-
-Architecture
-============
-
- * `The values or expressions assigned to the macros specified in the
- headers `<float.h>', `<limits.h>', and `<stdint.h>' (5.2.4.2,
- 7.18.2, 7.18.3).'
-
- * `The number, order, and encoding of bytes in any object (when not
- explicitly specified in this International Standard) (6.2.6.1).'
-
- * `The value of the result of the sizeof operator (6.5.3.4).'
-
-
-\1f
-File: gcc.info, Node: Locale-specific behavior implementation, Prev: Architecture implementation, Up: C Implementation
-
-Locale-specific behavior
-========================
-
- The behavior of these points are dependent on the implementation of
-the C library, and are not defined by GCC itself.
-
-\1f
-File: gcc.info, Node: C Extensions, Next: C++ Extensions, Prev: C Implementation, Up: Top
-
-Extensions to the C Language Family
-***********************************
-
- GNU C provides several language features not found in ISO standard C.
-(The `-pedantic' option directs GCC to print a warning message if any
-of these features is used.) To test for the availability of these
-features in conditional compilation, check for a predefined macro
-`__GNUC__', which is always defined under GCC.
-
- These extensions are available in C and Objective-C. Most of them
-are also available in C++. *Note Extensions to the C++ Language: C++
-Extensions, for extensions that apply _only_ to C++.
-
- Some features that are in ISO C99 but not C89 or C++ are also, as
-extensions, accepted by GCC in C89 mode and in C++.
-
-* Menu:
-
-* Statement Exprs:: Putting statements and declarations inside expressions.
-* Local Labels:: Labels local to a statement-expression.
-* Labels as Values:: Getting pointers to labels, and computed gotos.
-* Nested Functions:: As in Algol and Pascal, lexical scoping of functions.
-* Constructing Calls:: Dispatching a call to another function.
-* Typeof:: `typeof': referring to the type of an expression.
-* Lvalues:: Using `?:', `,' and casts in lvalues.
-* Conditionals:: Omitting the middle operand of a `?:' expression.
-* Long Long:: Double-word integers---`long long int'.
-* Complex:: Data types for complex numbers.
-* Hex Floats:: Hexadecimal floating-point constants.
-* Zero Length:: Zero-length arrays.
-* Variable Length:: Arrays whose length is computed at run time.
-* Variadic Macros:: Macros with a variable number of arguments.
-* Escaped Newlines:: Slightly looser rules for escaped newlines.
-* Multi-line Strings:: String literals with embedded newlines.
-* Subscripting:: Any array can be subscripted, even if not an lvalue.
-* Pointer Arith:: Arithmetic on `void'-pointers and function pointers.
-* Initializers:: Non-constant initializers.
-* Compound Literals:: Compound literals give structures, unions
- or arrays as values.
-* Designated Inits:: Labeling elements of initializers.
-* Cast to Union:: Casting to union type from any member of the union.
-* Case Ranges:: `case 1 ... 9' and such.
-* Mixed Declarations:: Mixing declarations and code.
-* Function Attributes:: Declaring that functions have no side effects,
- or that they can never return.
-* Attribute Syntax:: Formal syntax for attributes.
-* Function Prototypes:: Prototype declarations and old-style definitions.
-* C++ Comments:: C++ comments are recognized.
-* Dollar Signs:: Dollar sign is allowed in identifiers.
-* Character Escapes:: `\e' stands for the character <ESC>.
-* Variable Attributes:: Specifying attributes of variables.
-* Type Attributes:: Specifying attributes of types.
-* Alignment:: Inquiring about the alignment of a type or variable.
-* Inline:: Defining inline functions (as fast as macros).
-* Extended Asm:: Assembler instructions with C expressions as operands.
- (With them you can define ``built-in'' functions.)
-* Constraints:: Constraints for asm operands
-* Asm Labels:: Specifying the assembler name to use for a C symbol.
-* Explicit Reg Vars:: Defining variables residing in specified registers.
-* Alternate Keywords:: `__const__', `__asm__', etc., for header files.
-* Incomplete Enums:: `enum foo;', with details to follow.
-* Function Names:: Printable strings which are the name of the current
- function.
-* Return Address:: Getting the return or frame address of a function.
-* Vector Extensions:: Using vector instructions through built-in functions.
-* Other Builtins:: Other built-in functions.
-* Target Builtins:: Built-in functions specific to particular targets.
-* Pragmas:: Pragmas accepted by GCC.
-* Unnamed Fields:: Unnamed struct/union fields within structs/unions.
-
-\1f
-File: gcc.info, Node: Statement Exprs, Next: Local Labels, Up: C Extensions
-
-Statements and Declarations in Expressions
-==========================================
-
- A compound statement enclosed in parentheses may appear as an
-expression in GNU C. This allows you to use loops, switches, and local
-variables within an expression.
-
- Recall that a compound statement is a sequence of statements
-surrounded by braces; in this construct, parentheses go around the
-braces. For example:
-
- ({ int y = foo (); int z;
- if (y > 0) z = y;
- else z = - y;
- z; })
-
-is a valid (though slightly more complex than necessary) expression for
-the absolute value of `foo ()'.
-
- The last thing in the compound statement should be an expression
-followed by a semicolon; the value of this subexpression serves as the
-value of the entire construct. (If you use some other kind of statement
-last within the braces, the construct has type `void', and thus
-effectively no value.)
-
- This feature is especially useful in making macro definitions "safe"
-(so that they evaluate each operand exactly once). For example, the
-"maximum" function is commonly defined as a macro in standard C as
-follows:
-
- #define max(a,b) ((a) > (b) ? (a) : (b))
-
-But this definition computes either A or B twice, with bad results if
-the operand has side effects. In GNU C, if you know the type of the
-operands (here let's assume `int'), you can define the macro safely as
-follows:
-
- #define maxint(a,b) \
- ({int _a = (a), _b = (b); _a > _b ? _a : _b; })
-
- Embedded statements are not allowed in constant expressions, such as
-the value of an enumeration constant, the width of a bit-field, or the
-initial value of a static variable.
-
- If you don't know the type of the operand, you can still do this,
-but you must use `typeof' (*note Typeof::).
-
- Statement expressions are not supported fully in G++, and their fate
-there is unclear. (It is possible that they will become fully supported
-at some point, or that they will be deprecated, or that the bugs that
-are present will continue to exist indefinitely.) Presently, statement
-expressions do not work well as default arguments.
-
- In addition, there are semantic issues with statement-expressions in
-C++. If you try to use statement-expressions instead of inline
-functions in C++, you may be surprised at the way object destruction is
-handled. For example:
-
- #define foo(a) ({int b = (a); b + 3; })
-
-does not work the same way as:
-
- inline int foo(int a) { int b = a; return b + 3; }
-
-In particular, if the expression passed into `foo' involves the
-creation of temporaries, the destructors for those temporaries will be
-run earlier in the case of the macro than in the case of the function.
-
- These considerations mean that it is probably a bad idea to use
-statement-expressions of this form in header files that are designed to
-work with C++. (Note that some versions of the GNU C Library contained
-header files using statement-expression that lead to precisely this
-bug.)
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Local Labels, Next: Labels as Values, Prev: Statement Exprs, Up: C Extensions
-
-Locally Declared Labels
-=======================
-
- Each statement expression is a scope in which "local labels" can be
-declared. A local label is simply an identifier; you can jump to it
-with an ordinary `goto' statement, but only from within the statement
-expression it belongs to.
-
- A local label declaration looks like this:
-
- __label__ LABEL;
-
-or
-
- __label__ LABEL1, LABEL2, ...;
-
- Local label declarations must come at the beginning of the statement
-expression, right after the `({', before any ordinary declarations.
-
- The label declaration defines the label _name_, but does not define
-the label itself. You must do this in the usual way, with `LABEL:',
-within the statements of the statement expression.
-
- The local label feature is useful because statement expressions are
-often used in macros. If the macro contains nested loops, a `goto' can
-be useful for breaking out of them. However, an ordinary label whose
-scope is the whole function cannot be used: if the macro can be
-expanded several times in one function, the label will be multiply
-defined in that function. A local label avoids this problem. For
-example:
-
- #define SEARCH(array, target) \
- ({ \
- __label__ found; \
- typeof (target) _SEARCH_target = (target); \
- typeof (*(array)) *_SEARCH_array = (array); \
- int i, j; \
- int value; \
- for (i = 0; i < max; i++) \
- for (j = 0; j < max; j++) \
- if (_SEARCH_array[i][j] == _SEARCH_target) \
- { value = i; goto found; } \
- value = -1; \
- found: \
- value; \
- })
-
-\1f
-File: gcc.info, Node: Labels as Values, Next: Nested Functions, Prev: Local Labels, Up: C Extensions
-
-Labels as Values
-================
-
- You can get the address of a label defined in the current function
-(or a containing function) with the unary operator `&&'. The value has
-type `void *'. This value is a constant and can be used wherever a
-constant of that type is valid. For example:
-
- void *ptr;
- ...
- ptr = &&foo;
-
- To use these values, you need to be able to jump to one. This is
-done with the computed goto statement(1), `goto *EXP;'. For example,
-
- goto *ptr;
-
-Any expression of type `void *' is allowed.
-
- One way of using these constants is in initializing a static array
-that will serve as a jump table:
-
- static void *array[] = { &&foo, &&bar, &&hack };
-
- Then you can select a label with indexing, like this:
-
- goto *array[i];
-
-Note that this does not check whether the subscript is in bounds--array
-indexing in C never does that.
-
- Such an array of label values serves a purpose much like that of the
-`switch' statement. The `switch' statement is cleaner, so use that
-rather than an array unless the problem does not fit a `switch'
-statement very well.
-
- Another use of label values is in an interpreter for threaded code.
-The labels within the interpreter function can be stored in the
-threaded code for super-fast dispatching.
-
- You may not use this mechanism to jump to code in a different
-function. If you do that, totally unpredictable things will happen.
-The best way to avoid this is to store the label address only in
-automatic variables and never pass it as an argument.
-
- An alternate way to write the above example is
-
- static const int array[] = { &&foo - &&foo, &&bar - &&foo,
- &&hack - &&foo };
- goto *(&&foo + array[i]);
-
-This is more friendly to code living in shared libraries, as it reduces
-the number of dynamic relocations that are needed, and by consequence,
-allows the data to be read-only.
-
- ---------- Footnotes ----------
-
- (1) The analogous feature in Fortran is called an assigned goto, but
-that name seems inappropriate in C, where one can do more than simply
-store label addresses in label variables.
-
-\1f
-File: gcc.info, Node: Nested Functions, Next: Constructing Calls, Prev: Labels as Values, Up: C Extensions
-
-Nested Functions
-================
-
- A "nested function" is a function defined inside another function.
-(Nested functions are not supported for GNU C++.) The nested function's
-name is local to the block where it is defined. For example, here we
-define a nested function named `square', and call it twice:
-
- foo (double a, double b)
- {
- double square (double z) { return z * z; }
-
- return square (a) + square (b);
- }
-
- The nested function can access all the variables of the containing
-function that are visible at the point of its definition. This is
-called "lexical scoping". For example, here we show a nested function
-which uses an inherited variable named `offset':
-
- bar (int *array, int offset, int size)
- {
- int access (int *array, int index)
- { return array[index + offset]; }
- int i;
- ...
- for (i = 0; i < size; i++)
- ... access (array, i) ...
- }
-
- Nested function definitions are permitted within functions in the
-places where variable definitions are allowed; that is, in any block,
-before the first statement in the block.
-
- It is possible to call the nested function from outside the scope of
-its name by storing its address or passing the address to another
-function:
-
- hack (int *array, int size)
- {
- void store (int index, int value)
- { array[index] = value; }
-
- intermediate (store, size);
- }
-
- Here, the function `intermediate' receives the address of `store' as
-an argument. If `intermediate' calls `store', the arguments given to
-`store' are used to store into `array'. But this technique works only
-so long as the containing function (`hack', in this example) does not
-exit.
-
- If you try to call the nested function through its address after the
-containing function has exited, all hell will break loose. If you try
-to call it after a containing scope level has exited, and if it refers
-to some of the variables that are no longer in scope, you may be lucky,
-but it's not wise to take the risk. If, however, the nested function
-does not refer to anything that has gone out of scope, you should be
-safe.
-
- GCC implements taking the address of a nested function using a
-technique called "trampolines". A paper describing them is available as
-
-`http://people.debian.org/~aaronl/Usenix88-lexic.pdf'.
-
- A nested function can jump to a label inherited from a containing
-function, provided the label was explicitly declared in the containing
-function (*note Local Labels::). Such a jump returns instantly to the
-containing function, exiting the nested function which did the `goto'
-and any intermediate functions as well. Here is an example:
-
- bar (int *array, int offset, int size)
- {
- __label__ failure;
- int access (int *array, int index)
- {
- if (index > size)
- goto failure;
- return array[index + offset];
- }
- int i;
- ...
- for (i = 0; i < size; i++)
- ... access (array, i) ...
- ...
- return 0;
-
- /* Control comes here from `access'
- if it detects an error. */
- failure:
- return -1;
- }
-
- A nested function always has internal linkage. Declaring one with
-`extern' is erroneous. If you need to declare the nested function
-before its definition, use `auto' (which is otherwise meaningless for
-function declarations).
-
- bar (int *array, int offset, int size)
- {
- __label__ failure;
- auto int access (int *, int);
- ...
- int access (int *array, int index)
- {
- if (index > size)
- goto failure;
- return array[index + offset];
- }
- ...
- }
-
-\1f
-File: gcc.info, Node: Constructing Calls, Next: Typeof, Prev: Nested Functions, Up: C Extensions
-
-Constructing Function Calls
-===========================
-
- Using the built-in functions described below, you can record the
-arguments a function received, and call another function with the same
-arguments, without knowing the number or types of the arguments.
-
- You can also record the return value of that function call, and
-later return that value, without knowing what data type the function
-tried to return (as long as your caller expects that data type).
-
- - Built-in Function: void * __builtin_apply_args ()
- This built-in function returns a pointer to data describing how to
- perform a call with the same arguments as were passed to the
- current function.
-
- The function saves the arg pointer register, structure value
- address, and all registers that might be used to pass arguments to
- a function into a block of memory allocated on the stack. Then it
- returns the address of that block.
-
- - Built-in Function: void * __builtin_apply (void (*FUNCTION)(), void
- *ARGUMENTS, size_t SIZE)
- This built-in function invokes FUNCTION with a copy of the
- parameters described by ARGUMENTS and SIZE.
-
- The value of ARGUMENTS should be the value returned by
- `__builtin_apply_args'. The argument SIZE specifies the size of
- the stack argument data, in bytes.
-
- This function returns a pointer to data describing how to return
- whatever value was returned by FUNCTION. The data is saved in a
- block of memory allocated on the stack.
-
- It is not always simple to compute the proper value for SIZE. The
- value is used by `__builtin_apply' to compute the amount of data
- that should be pushed on the stack and copied from the incoming
- argument area.
-
- - Built-in Function: void __builtin_return (void *RESULT)
- This built-in function returns the value described by RESULT from
- the containing function. You should specify, for RESULT, a value
- returned by `__builtin_apply'.
-
-\1f
-File: gcc.info, Node: Typeof, Next: Lvalues, Prev: Constructing Calls, Up: C Extensions
-
-Referring to a Type with `typeof'
-=================================
-
- Another way to refer to the type of an expression is with `typeof'.
-The syntax of using of this keyword looks like `sizeof', but the
-construct acts semantically like a type name defined with `typedef'.
-
- There are two ways of writing the argument to `typeof': with an
-expression or with a type. Here is an example with an expression:
-
- typeof (x[0](1))
-
-This assumes that `x' is an array of pointers to functions; the type
-described is that of the values of the functions.
-
- Here is an example with a typename as the argument:
-
- typeof (int *)
-
-Here the type described is that of pointers to `int'.
-
- If you are writing a header file that must work when included in ISO
-C programs, write `__typeof__' instead of `typeof'. *Note Alternate
-Keywords::.
-
- A `typeof'-construct can be used anywhere a typedef name could be
-used. For example, you can use it in a declaration, in a cast, or
-inside of `sizeof' or `typeof'.
-
- `typeof' is often useful in conjunction with the
-statements-within-expressions feature. Here is how the two together can
-be used to define a safe "maximum" macro that operates on any
-arithmetic type and evaluates each of its arguments exactly once:
-
- #define max(a,b) \
- ({ typeof (a) _a = (a); \
- typeof (b) _b = (b); \
- _a > _b ? _a : _b; })
-
- The reason for using names that start with underscores for the local
-variables is to avoid conflicts with variable names that occur within
-the expressions that are substituted for `a' and `b'. Eventually we
-hope to design a new form of declaration syntax that allows you to
-declare variables whose scopes start only after their initializers;
-this will be a more reliable way to prevent such conflicts.
-
-Some more examples of the use of `typeof':
-
- * This declares `y' with the type of what `x' points to.
-
- typeof (*x) y;
-
- * This declares `y' as an array of such values.
-
- typeof (*x) y[4];
-
- * This declares `y' as an array of pointers to characters:
-
- typeof (typeof (char *)[4]) y;
-
- It is equivalent to the following traditional C declaration:
-
- char *y[4];
-
- To see the meaning of the declaration using `typeof', and why it
- might be a useful way to write, let's rewrite it with these macros:
-
- #define pointer(T) typeof(T *)
- #define array(T, N) typeof(T [N])
-
- Now the declaration can be rewritten this way:
-
- array (pointer (char), 4) y;
-
- Thus, `array (pointer (char), 4)' is the type of arrays of 4
- pointers to `char'.
-
- _Compatibility Note:_ In addition to `typeof', GCC 2 supported a
-more limited extension which permitted one to write
-
- typedef T = EXPR;
-
-with the effect of declaring T to have the type of the expression EXPR.
-This extension does not work with GCC 3 (versions between 3.0 and 3.2
-will crash; 3.2.1 and later give an error). Code which relies on it
-should be rewritten to use `typeof':
-
- typedef typeof(EXPR) T;
-
-This will work with all versions of GCC.
-
-\1f
-File: gcc.info, Node: Lvalues, Next: Conditionals, Prev: Typeof, Up: C Extensions
-
-Generalized Lvalues
-===================
-
- Compound expressions, conditional expressions and casts are allowed
-as lvalues provided their operands are lvalues. This means that you
-can take their addresses or store values into them.
-
- Standard C++ allows compound expressions and conditional expressions
-as lvalues, and permits casts to reference type, so use of this
-extension is deprecated for C++ code.
-
- For example, a compound expression can be assigned, provided the last
-expression in the sequence is an lvalue. These two expressions are
-equivalent:
-
- (a, b) += 5
- a, (b += 5)
-
- Similarly, the address of the compound expression can be taken.
-These two expressions are equivalent:
-
- &(a, b)
- a, &b
-
- A conditional expression is a valid lvalue if its type is not void
-and the true and false branches are both valid lvalues. For example,
-these two expressions are equivalent:
-
- (a ? b : c) = 5
- (a ? b = 5 : (c = 5))
-
- A cast is a valid lvalue if its operand is an lvalue. A simple
-assignment whose left-hand side is a cast works by converting the
-right-hand side first to the specified type, then to the type of the
-inner left-hand side expression. After this is stored, the value is
-converted back to the specified type to become the value of the
-assignment. Thus, if `a' has type `char *', the following two
-expressions are equivalent:
-
- (int)a = 5
- (int)(a = (char *)(int)5)
-
- An assignment-with-arithmetic operation such as `+=' applied to a
-cast performs the arithmetic using the type resulting from the cast,
-and then continues as in the previous case. Therefore, these two
-expressions are equivalent:
-
- (int)a += 5
- (int)(a = (char *)(int) ((int)a + 5))
-
- You cannot take the address of an lvalue cast, because the use of its
-address would not work out coherently. Suppose that `&(int)f' were
-permitted, where `f' has type `float'. Then the following statement
-would try to store an integer bit-pattern where a floating point number
-belongs:
-
- *&(int)f = 1;
-
- This is quite different from what `(int)f = 1' would do--that would
-convert 1 to floating point and store it. Rather than cause this
-inconsistency, we think it is better to prohibit use of `&' on a cast.
-
- If you really do want an `int *' pointer with the address of `f',
-you can simply write `(int *)&f'.
-
-\1f
-File: gcc.info, Node: Conditionals, Next: Long Long, Prev: Lvalues, Up: C Extensions
-
-Conditionals with Omitted Operands
-==================================
-
- The middle operand in a conditional expression may be omitted. Then
-if the first operand is nonzero, its value is the value of the
-conditional expression.
-
- Therefore, the expression
-
- x ? : y
-
-has the value of `x' if that is nonzero; otherwise, the value of `y'.
-
- This example is perfectly equivalent to
-
- x ? x : y
-
-In this simple case, the ability to omit the middle operand is not
-especially useful. When it becomes useful is when the first operand
-does, or may (if it is a macro argument), contain a side effect. Then
-repeating the operand in the middle would perform the side effect
-twice. Omitting the middle operand uses the value already computed
-without the undesirable effects of recomputing it.
-
-\1f
-File: gcc.info, Node: Long Long, Next: Complex, Prev: Conditionals, Up: C Extensions
-
-Double-Word Integers
-====================
-
- ISO C99 supports data types for integers that are at least 64 bits
-wide, and as an extension GCC supports them in C89 mode and in C++.
-Simply write `long long int' for a signed integer, or `unsigned long
-long int' for an unsigned integer. To make an integer constant of type
-`long long int', add the suffix `LL' to the integer. To make an
-integer constant of type `unsigned long long int', add the suffix `ULL'
-to the integer.
-
- You can use these types in arithmetic like any other integer types.
-Addition, subtraction, and bitwise boolean operations on these types
-are open-coded on all types of machines. Multiplication is open-coded
-if the machine supports fullword-to-doubleword a widening multiply
-instruction. Division and shifts are open-coded only on machines that
-provide special support. The operations that are not open-coded use
-special library routines that come with GCC.
-
- There may be pitfalls when you use `long long' types for function
-arguments, unless you declare function prototypes. If a function
-expects type `int' for its argument, and you pass a value of type `long
-long int', confusion will result because the caller and the subroutine
-will disagree about the number of bytes for the argument. Likewise, if
-the function expects `long long int' and you pass `int'. The best way
-to avoid such problems is to use prototypes.
-
-\1f
-File: gcc.info, Node: Complex, Next: Hex Floats, Prev: Long Long, Up: C Extensions
-
-Complex Numbers
-===============
-
- ISO C99 supports complex floating data types, and as an extension GCC
-supports them in C89 mode and in C++, and supports complex integer data
-types which are not part of ISO C99. You can declare complex types
-using the keyword `_Complex'. As an extension, the older GNU keyword
-`__complex__' is also supported.
-
- For example, `_Complex double x;' declares `x' as a variable whose
-real part and imaginary part are both of type `double'. `_Complex
-short int y;' declares `y' to have real and imaginary parts of type
-`short int'; this is not likely to be useful, but it shows that the set
-of complex types is complete.
-
- To write a constant with a complex data type, use the suffix `i' or
-`j' (either one; they are equivalent). For example, `2.5fi' has type
-`_Complex float' and `3i' has type `_Complex int'. Such a constant
-always has a pure imaginary value, but you can form any complex value
-you like by adding one to a real constant. This is a GNU extension; if
-you have an ISO C99 conforming C library (such as GNU libc), and want
-to construct complex constants of floating type, you should include
-`<complex.h>' and use the macros `I' or `_Complex_I' instead.
-
- To extract the real part of a complex-valued expression EXP, write
-`__real__ EXP'. Likewise, use `__imag__' to extract the imaginary
-part. This is a GNU extension; for values of floating type, you should
-use the ISO C99 functions `crealf', `creal', `creall', `cimagf',
-`cimag' and `cimagl', declared in `<complex.h>' and also provided as
-built-in functions by GCC.
-
- The operator `~' performs complex conjugation when used on a value
-with a complex type. This is a GNU extension; for values of floating
-type, you should use the ISO C99 functions `conjf', `conj' and `conjl',
-declared in `<complex.h>' and also provided as built-in functions by
-GCC.
-
- GCC can allocate complex automatic variables in a noncontiguous
-fashion; it's even possible for the real part to be in a register while
-the imaginary part is on the stack (or vice-versa). None of the
-supported debugging info formats has a way to represent noncontiguous
-allocation like this, so GCC describes a noncontiguous complex variable
-as if it were two separate variables of noncomplex type. If the
-variable's actual name is `foo', the two fictitious variables are named
-`foo$real' and `foo$imag'. You can examine and set these two
-fictitious variables with your debugger.
-
- A future version of GDB will know how to recognize such pairs and
-treat them as a single variable with a complex type.
-
-\1f
-File: gcc.info, Node: Hex Floats, Next: Zero Length, Prev: Complex, Up: C Extensions
-
-Hex Floats
-==========
-
- ISO C99 supports floating-point numbers written not only in the usual
-decimal notation, such as `1.55e1', but also numbers such as `0x1.fp3'
-written in hexadecimal format. As a GNU extension, GCC supports this
-in C89 mode (except in some cases when strictly conforming) and in C++.
-In that format the `0x' hex introducer and the `p' or `P' exponent
-field are mandatory. The exponent is a decimal number that indicates
-the power of 2 by which the significant part will be multiplied. Thus
-`0x1.f' is 1 15/16, `p3' multiplies it by 8, and the value of `0x1.fp3'
-is the same as `1.55e1'.
-
- Unlike for floating-point numbers in the decimal notation the
-exponent is always required in the hexadecimal notation. Otherwise the
-compiler would not be able to resolve the ambiguity of, e.g., `0x1.f'.
-This could mean `1.0f' or `1.9375' since `f' is also the extension for
-floating-point constants of type `float'.
-
-\1f
-File: gcc.info, Node: Zero Length, Next: Variable Length, Prev: Hex Floats, Up: C Extensions
-
-Arrays of Length Zero
-=====================
-
- Zero-length arrays are allowed in GNU C. They are very useful as the
-last element of a structure which is really a header for a
-variable-length object:
-
- struct line {
- int length;
- char contents[0];
- };
-
- struct line *thisline = (struct line *)
- malloc (sizeof (struct line) + this_length);
- thisline->length = this_length;
-
- In ISO C89, you would have to give `contents' a length of 1, which
-means either you waste space or complicate the argument to `malloc'.
-
- In ISO C99, you would use a "flexible array member", which is
-slightly different in syntax and semantics:
-
- * Flexible array members are written as `contents[]' without the `0'.
-
- * Flexible array members have incomplete type, and so the `sizeof'
- operator may not be applied. As a quirk of the original
- implementation of zero-length arrays, `sizeof' evaluates to zero.
-
- * Flexible array members may only appear as the last member of a
- `struct' that is otherwise non-empty.
-
- GCC versions before 3.0 allowed zero-length arrays to be statically
-initialized, as if they were flexible arrays. In addition to those
-cases that were useful, it also allowed initializations in situations
-that would corrupt later data. Non-empty initialization of zero-length
-arrays is now treated like any case where there are more initializer
-elements than the array holds, in that a suitable warning about "excess
-elements in array" is given, and the excess elements (all of them, in
-this case) are ignored.
-
- Instead GCC allows static initialization of flexible array members.
-This is equivalent to defining a new structure containing the original
-structure followed by an array of sufficient size to contain the data.
-I.e. in the following, `f1' is constructed as if it were declared like
-`f2'.
-
- struct f1 {
- int x; int y[];
- } f1 = { 1, { 2, 3, 4 } };
-
- struct f2 {
- struct f1 f1; int data[3];
- } f2 = { { 1 }, { 2, 3, 4 } };
-
-The convenience of this extension is that `f1' has the desired type,
-eliminating the need to consistently refer to `f2.f1'.
-
- This has symmetry with normal static arrays, in that an array of
-unknown size is also written with `[]'.
-
- Of course, this extension only makes sense if the extra data comes at
-the end of a top-level object, as otherwise we would be overwriting
-data at subsequent offsets. To avoid undue complication and confusion
-with initialization of deeply nested arrays, we simply disallow any
-non-empty initialization except when the structure is the top-level
-object. For example:
-
- struct foo { int x; int y[]; };
- struct bar { struct foo z; };
-
- struct foo a = { 1, { 2, 3, 4 } }; // Valid.
- struct bar b = { { 1, { 2, 3, 4 } } }; // Invalid.
- struct bar c = { { 1, { } } }; // Valid.
- struct foo d[1] = { { 1 { 2, 3, 4 } } }; // Invalid.
-
-\1f
-File: gcc.info, Node: Variable Length, Next: Variadic Macros, Prev: Zero Length, Up: C Extensions
-
-Arrays of Variable Length
-=========================
-
- Variable-length automatic arrays are allowed in ISO C99, and as an
-extension GCC accepts them in C89 mode and in C++. (However, GCC's
-implementation of variable-length arrays does not yet conform in detail
-to the ISO C99 standard.) These arrays are declared like any other
-automatic arrays, but with a length that is not a constant expression.
-The storage is allocated at the point of declaration and deallocated
-when the brace-level is exited. For example:
-
- FILE *
- concat_fopen (char *s1, char *s2, char *mode)
- {
- char str[strlen (s1) + strlen (s2) + 1];
- strcpy (str, s1);
- strcat (str, s2);
- return fopen (str, mode);
- }
-
- Jumping or breaking out of the scope of the array name deallocates
-the storage. Jumping into the scope is not allowed; you get an error
-message for it.
-
- You can use the function `alloca' to get an effect much like
-variable-length arrays. The function `alloca' is available in many
-other C implementations (but not in all). On the other hand,
-variable-length arrays are more elegant.
-
- There are other differences between these two methods. Space
-allocated with `alloca' exists until the containing _function_ returns.
-The space for a variable-length array is deallocated as soon as the
-array name's scope ends. (If you use both variable-length arrays and
-`alloca' in the same function, deallocation of a variable-length array
-will also deallocate anything more recently allocated with `alloca'.)
-
- You can also use variable-length arrays as arguments to functions:
-
- struct entry
- tester (int len, char data[len][len])
- {
- ...
- }
-
- The length of an array is computed once when the storage is allocated
-and is remembered for the scope of the array in case you access it with
-`sizeof'.
-
- If you want to pass the array first and the length afterward, you can
-use a forward declaration in the parameter list--another GNU extension.
-
- struct entry
- tester (int len; char data[len][len], int len)
- {
- ...
- }
-
- The `int len' before the semicolon is a "parameter forward
-declaration", and it serves the purpose of making the name `len' known
-when the declaration of `data' is parsed.
-
- You can write any number of such parameter forward declarations in
-the parameter list. They can be separated by commas or semicolons, but
-the last one must end with a semicolon, which is followed by the "real"
-parameter declarations. Each forward declaration must match a "real"
-declaration in parameter name and data type. ISO C99 does not support
-parameter forward declarations.
-
-\1f
-File: gcc.info, Node: Variadic Macros, Next: Escaped Newlines, Prev: Variable Length, Up: C Extensions
-
-Macros with a Variable Number of Arguments.
-===========================================
-
- In the ISO C standard of 1999, a macro can be declared to accept a
-variable number of arguments much as a function can. The syntax for
-defining the macro is similar to that of a function. Here is an
-example:
-
- #define debug(format, ...) fprintf (stderr, format, __VA_ARGS__)
-
- Here `...' is a "variable argument". In the invocation of such a
-macro, it represents the zero or more tokens until the closing
-parenthesis that ends the invocation, including any commas. This set of
-tokens replaces the identifier `__VA_ARGS__' in the macro body wherever
-it appears. See the CPP manual for more information.
-
- GCC has long supported variadic macros, and used a different syntax
-that allowed you to give a name to the variable arguments just like any
-other argument. Here is an example:
-
- #define debug(format, args...) fprintf (stderr, format, args)
-
- This is in all ways equivalent to the ISO C example above, but
-arguably more readable and descriptive.
-
- GNU CPP has two further variadic macro extensions, and permits them
-to be used with either of the above forms of macro definition.
-
- In standard C, you are not allowed to leave the variable argument out
-entirely; but you are allowed to pass an empty argument. For example,
-this invocation is invalid in ISO C, because there is no comma after
-the string:
-
- debug ("A message")
-
- GNU CPP permits you to completely omit the variable arguments in this
-way. In the above examples, the compiler would complain, though since
-the expansion of the macro still has the extra comma after the format
-string.
-
- To help solve this problem, CPP behaves specially for variable
-arguments used with the token paste operator, `##'. If instead you
-write
-
- #define debug(format, ...) fprintf (stderr, format, ## __VA_ARGS__)
-
- and if the variable arguments are omitted or empty, the `##'
-operator causes the preprocessor to remove the comma before it. If you
-do provide some variable arguments in your macro invocation, GNU CPP
-does not complain about the paste operation and instead places the
-variable arguments after the comma. Just like any other pasted macro
-argument, these arguments are not macro expanded.
-
-\1f
-File: gcc.info, Node: Escaped Newlines, Next: Multi-line Strings, Prev: Variadic Macros, Up: C Extensions
-
-Slightly Looser Rules for Escaped Newlines
-==========================================
-
- Recently, the non-traditional preprocessor has relaxed its treatment
-of escaped newlines. Previously, the newline had to immediately follow
-a backslash. The current implementation allows whitespace in the form
-of spaces, horizontal and vertical tabs, and form feeds between the
-backslash and the subsequent newline. The preprocessor issues a
-warning, but treats it as a valid escaped newline and combines the two
-lines to form a single logical line. This works within comments and
-tokens, including multi-line strings, as well as between tokens.
-Comments are _not_ treated as whitespace for the purposes of this
-relaxation, since they have not yet been replaced with spaces.
-
-\1f
-File: gcc.info, Node: Multi-line Strings, Next: Subscripting, Prev: Escaped Newlines, Up: C Extensions
-
-String Literals with Embedded Newlines
-======================================
-
- As an extension, GNU CPP permits string literals to cross multiple
-lines without escaping the embedded newlines. Each embedded newline is
-replaced with a single `\n' character in the resulting string literal,
-regardless of what form the newline took originally.
-
- CPP currently allows such strings in directives as well (other than
-the `#include' family). This is deprecated and will eventually be
-removed.
-
-\1f
-File: gcc.info, Node: Subscripting, Next: Pointer Arith, Prev: Multi-line Strings, Up: C Extensions
-
-Non-Lvalue Arrays May Have Subscripts
-=====================================
-
- In ISO C99, arrays that are not lvalues still decay to pointers, and
-may be subscripted, although they may not be modified or used after the
-next sequence point and the unary `&' operator may not be applied to
-them. As an extension, GCC allows such arrays to be subscripted in C89
-mode, though otherwise they do not decay to pointers outside C99 mode.
-For example, this is valid in GNU C though not valid in C89:
-
- struct foo {int a[4];};
-
- struct foo f();
-
- bar (int index)
- {
- return f().a[index];
- }
-
-\1f
-File: gcc.info, Node: Pointer Arith, Next: Initializers, Prev: Subscripting, Up: C Extensions
-
-Arithmetic on `void'- and Function-Pointers
-===========================================
-
- In GNU C, addition and subtraction operations are supported on
-pointers to `void' and on pointers to functions. This is done by
-treating the size of a `void' or of a function as 1.
-
- A consequence of this is that `sizeof' is also allowed on `void' and
-on function types, and returns 1.
-
- The option `-Wpointer-arith' requests a warning if these extensions
-are used.
-
-\1f
-File: gcc.info, Node: Initializers, Next: Compound Literals, Prev: Pointer Arith, Up: C Extensions
-
-Non-Constant Initializers
-=========================
-
- As in standard C++ and ISO C99, the elements of an aggregate
-initializer for an automatic variable are not required to be constant
-expressions in GNU C. Here is an example of an initializer with
-run-time varying elements:
-
- foo (float f, float g)
- {
- float beat_freqs[2] = { f-g, f+g };
- ...
- }
-
-\1f
-File: gcc.info, Node: Compound Literals, Next: Designated Inits, Prev: Initializers, Up: C Extensions
-
-Compound Literals
-=================
-
- ISO C99 supports compound literals. A compound literal looks like a
-cast containing an initializer. Its value is an object of the type
-specified in the cast, containing the elements specified in the
-initializer; it is an lvalue. As an extension, GCC supports compound
-literals in C89 mode and in C++.
-
- Usually, the specified type is a structure. Assume that `struct
-foo' and `structure' are declared as shown:
-
- struct foo {int a; char b[2];} structure;
-
-Here is an example of constructing a `struct foo' with a compound
-literal:
-
- structure = ((struct foo) {x + y, 'a', 0});
-
-This is equivalent to writing the following:
-
- {
- struct foo temp = {x + y, 'a', 0};
- structure = temp;
- }
-
- You can also construct an array. If all the elements of the
-compound literal are (made up of) simple constant expressions, suitable
-for use in initializers of objects of static storage duration, then the
-compound literal can be coerced to a pointer to its first element and
-used in such an initializer, as shown here:
-
- char **foo = (char *[]) { "x", "y", "z" };
-
- Compound literals for scalar types and union types are is also
-allowed, but then the compound literal is equivalent to a cast.
-
- As a GNU extension, GCC allows initialization of objects with static
-storage duration by compound literals (which is not possible in ISO
-C99, because the initializer is not a constant). It is handled as if
-the object was initialized only with the bracket enclosed list if
-compound literal's and object types match. The initializer list of the
-compound literal must be constant. If the object being initialized has
-array type of unknown size, the size is determined by compound literal
-size.
-
- static struct foo x = (struct foo) {1, 'a', 'b'};
- static int y[] = (int []) {1, 2, 3};
- static int z[] = (int [3]) {1};
-
-The above lines are equivalent to the following:
- static struct foo x = {1, 'a', 'b'};
- static int y[] = {1, 2, 3};
- static int z[] = {1, 0, 0};
-
-\1f
-File: gcc.info, Node: Designated Inits, Next: Cast to Union, Prev: Compound Literals, Up: C Extensions
-
-Designated Initializers
-=======================
-
- Standard C89 requires the elements of an initializer to appear in a
-fixed order, the same as the order of the elements in the array or
-structure being initialized.
-
- In ISO C99 you can give the elements in any order, specifying the
-array indices or structure field names they apply to, and GNU C allows
-this as an extension in C89 mode as well. This extension is not
-implemented in GNU C++.
-
- To specify an array index, write `[INDEX] =' before the element
-value. For example,
-
- int a[6] = { [4] = 29, [2] = 15 };
-
-is equivalent to
-
- int a[6] = { 0, 0, 15, 0, 29, 0 };
-
-The index values must be constant expressions, even if the array being
-initialized is automatic.
-
- An alternative syntax for this which has been obsolete since GCC 2.5
-but GCC still accepts is to write `[INDEX]' before the element value,
-with no `='.
-
- To initialize a range of elements to the same value, write `[FIRST
-... LAST] = VALUE'. This is a GNU extension. For example,
-
- int widths[] = { [0 ... 9] = 1, [10 ... 99] = 2, [100] = 3 };
-
-If the value in it has side-effects, the side-effects will happen only
-once, not for each initialized field by the range initializer.
-
-Note that the length of the array is the highest value specified plus
-one.
-
- In a structure initializer, specify the name of a field to initialize
-with `.FIELDNAME =' before the element value. For example, given the
-following structure,
-
- struct point { int x, y; };
-
-the following initialization
-
- struct point p = { .y = yvalue, .x = xvalue };
-
-is equivalent to
-
- struct point p = { xvalue, yvalue };
-
- Another syntax which has the same meaning, obsolete since GCC 2.5, is
-`FIELDNAME:', as shown here:
-
- struct point p = { y: yvalue, x: xvalue };
-
- The `[INDEX]' or `.FIELDNAME' is known as a "designator". You can
-also use a designator (or the obsolete colon syntax) when initializing
-a union, to specify which element of the union should be used. For
-example,
-
- union foo { int i; double d; };
-
- union foo f = { .d = 4 };
-
-will convert 4 to a `double' to store it in the union using the second
-element. By contrast, casting 4 to type `union foo' would store it
-into the union as the integer `i', since it is an integer. (*Note Cast
-to Union::.)
-
- You can combine this technique of naming elements with ordinary C
-initialization of successive elements. Each initializer element that
-does not have a designator applies to the next consecutive element of
-the array or structure. For example,
-
- int a[6] = { [1] = v1, v2, [4] = v4 };
-
-is equivalent to
-
- int a[6] = { 0, v1, v2, 0, v4, 0 };
-
- Labeling the elements of an array initializer is especially useful
-when the indices are characters or belong to an `enum' type. For
-example:
-
- int whitespace[256]
- = { [' '] = 1, ['\t'] = 1, ['\h'] = 1,
- ['\f'] = 1, ['\n'] = 1, ['\r'] = 1 };
-
- You can also write a series of `.FIELDNAME' and `[INDEX]'
-designators before an `=' to specify a nested subobject to initialize;
-the list is taken relative to the subobject corresponding to the
-closest surrounding brace pair. For example, with the `struct point'
-declaration above:
-
- struct point ptarray[10] = { [2].y = yv2, [2].x = xv2, [0].x = xv0 };
-
-If the same field is initialized multiple times, it will have value from
-the last initialization. If any such overridden initialization has
-side-effect, it is unspecified whether the side-effect happens or not.
-Currently, gcc will discard them and issue a warning.
-
-\1f
-File: gcc.info, Node: Case Ranges, Next: Mixed Declarations, Prev: Cast to Union, Up: C Extensions
-
-Case Ranges
-===========
-
- You can specify a range of consecutive values in a single `case'
-label, like this:
-
- case LOW ... HIGH:
-
-This has the same effect as the proper number of individual `case'
-labels, one for each integer value from LOW to HIGH, inclusive.
-
- This feature is especially useful for ranges of ASCII character
-codes:
-
- case 'A' ... 'Z':
-
- *Be careful:* Write spaces around the `...', for otherwise it may be
-parsed wrong when you use it with integer values. For example, write
-this:
-
- case 1 ... 5:
-
-rather than this:
-
- case 1...5:
-
-\1f
-File: gcc.info, Node: Cast to Union, Next: Case Ranges, Prev: Designated Inits, Up: C Extensions
-
-Cast to a Union Type
-====================
-
- A cast to union type is similar to other casts, except that the type
-specified is a union type. You can specify the type either with `union
-TAG' or with a typedef name. A cast to union is actually a constructor
-though, not a cast, and hence does not yield an lvalue like normal
-casts. (*Note Compound Literals::.)
-
- The types that may be cast to the union type are those of the members
-of the union. Thus, given the following union and variables:
-
- union foo { int i; double d; };
- int x;
- double y;
-
-both `x' and `y' can be cast to type `union foo'.
-
- Using the cast as the right-hand side of an assignment to a variable
-of union type is equivalent to storing in a member of the union:
-
- union foo u;
- ...
- u = (union foo) x == u.i = x
- u = (union foo) y == u.d = y
-
- You can also use the union cast as a function argument:
-
- void hack (union foo);
- ...
- hack ((union foo) x);
-
-\1f
-File: gcc.info, Node: Mixed Declarations, Next: Function Attributes, Prev: Case Ranges, Up: C Extensions
-
-Mixed Declarations and Code
-===========================
-
- ISO C99 and ISO C++ allow declarations and code to be freely mixed
-within compound statements. As an extension, GCC also allows this in
-C89 mode. For example, you could do:
-
- int i;
- ...
- i++;
- int j = i + 2;
-
- Each identifier is visible from where it is declared until the end of
-the enclosing block.
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Function Attributes, Next: Attribute Syntax, Prev: Mixed Declarations, Up: C Extensions
-
-Declaring Attributes of Functions
-=================================
-
- In GNU C, you declare certain things about functions called in your
-program which help the compiler optimize function calls and check your
-code more carefully.
-
- The keyword `__attribute__' allows you to specify special attributes
-when making a declaration. This keyword is followed by an attribute
-specification inside double parentheses. The following attributes are
-currently defined for functions on all targets: `noreturn', `noinline',
-`always_inline', `pure', `const', `format', `format_arg',
-`no_instrument_function', `section', `constructor', `destructor',
-`used', `unused', `deprecated', `weak', `malloc', and `alias'. Several
-other attributes are defined for functions on particular target
-systems. Other attributes, including `section' are supported for
-variables declarations (*note Variable Attributes::) and for types
-(*note Type Attributes::).
-
- You may also specify attributes with `__' preceding and following
-each keyword. This allows you to use them in header files without
-being concerned about a possible macro of the same name. For example,
-you may use `__noreturn__' instead of `noreturn'.
-
- *Note Attribute Syntax::, for details of the exact syntax for using
-attributes.
-
-`noreturn'
- A few standard library functions, such as `abort' and `exit',
- cannot return. GCC knows this automatically. Some programs define
- their own functions that never return. You can declare them
- `noreturn' to tell the compiler this fact. For example,
-
- void fatal () __attribute__ ((noreturn));
-
- void
- fatal (...)
- {
- ... /* Print error message. */ ...
- exit (1);
- }
-
- The `noreturn' keyword tells the compiler to assume that `fatal'
- cannot return. It can then optimize without regard to what would
- happen if `fatal' ever did return. This makes slightly better
- code. More importantly, it helps avoid spurious warnings of
- uninitialized variables.
-
- Do not assume that registers saved by the calling function are
- restored before calling the `noreturn' function.
-
- It does not make sense for a `noreturn' function to have a return
- type other than `void'.
-
- The attribute `noreturn' is not implemented in GCC versions
- earlier than 2.5. An alternative way to declare that a function
- does not return, which works in the current version and in some
- older versions, is as follows:
-
- typedef void voidfn ();
-
- volatile voidfn fatal;
-
-`noinline'
- This function attribute prevents a function from being considered
- for inlining.
-
-`always_inline'
- Generally, functions are not inlined unless optimization is
- specified. For functions declared inline, this attribute inlines
- the function even if no optimization level was specified.
-
-`pure'
- Many functions have no effects except the return value and their
- return value depends only on the parameters and/or global
- variables. Such a function can be subject to common subexpression
- elimination and loop optimization just as an arithmetic operator
- would be. These functions should be declared with the attribute
- `pure'. For example,
-
- int square (int) __attribute__ ((pure));
-
- says that the hypothetical function `square' is safe to call fewer
- times than the program says.
-
- Some of common examples of pure functions are `strlen' or `memcmp'.
- Interesting non-pure functions are functions with infinite loops
- or those depending on volatile memory or other system resource,
- that may change between two consecutive calls (such as `feof' in a
- multithreading environment).
-
- The attribute `pure' is not implemented in GCC versions earlier
- than 2.96.
-
-`const'
- Many functions do not examine any values except their arguments,
- and have no effects except the return value. Basically this is
- just slightly more strict class than the `pure' attribute above,
- since function is not allowed to read global memory.
-
- Note that a function that has pointer arguments and examines the
- data pointed to must _not_ be declared `const'. Likewise, a
- function that calls a non-`const' function usually must not be
- `const'. It does not make sense for a `const' function to return
- `void'.
-
- The attribute `const' is not implemented in GCC versions earlier
- than 2.5. An alternative way to declare that a function has no
- side effects, which works in the current version and in some older
- versions, is as follows:
-
- typedef int intfn ();
-
- extern const intfn square;
-
- This approach does not work in GNU C++ from 2.6.0 on, since the
- language specifies that the `const' must be attached to the return
- value.
-
-`format (ARCHETYPE, STRING-INDEX, FIRST-TO-CHECK)'
- The `format' attribute specifies that a function takes `printf',
- `scanf', `strftime' or `strfmon' style arguments which should be
- type-checked against a format string. For example, the
- declaration:
-
- extern int
- my_printf (void *my_object, const char *my_format, ...)
- __attribute__ ((format (printf, 2, 3)));
-
- causes the compiler to check the arguments in calls to `my_printf'
- for consistency with the `printf' style format string argument
- `my_format'.
-
- The parameter ARCHETYPE determines how the format string is
- interpreted, and should be `printf', `scanf', `strftime' or
- `strfmon'. (You can also use `__printf__', `__scanf__',
- `__strftime__' or `__strfmon__'.) The parameter STRING-INDEX
- specifies which argument is the format string argument (starting
- from 1), while FIRST-TO-CHECK is the number of the first argument
- to check against the format string. For functions where the
- arguments are not available to be checked (such as `vprintf'),
- specify the third parameter as zero. In this case the compiler
- only checks the format string for consistency. For `strftime'
- formats, the third parameter is required to be zero.
-
- In the example above, the format string (`my_format') is the second
- argument of the function `my_print', and the arguments to check
- start with the third argument, so the correct parameters for the
- format attribute are 2 and 3.
-
- The `format' attribute allows you to identify your own functions
- which take format strings as arguments, so that GCC can check the
- calls to these functions for errors. The compiler always (unless
- `-ffreestanding' is used) checks formats for the standard library
- functions `printf', `fprintf', `sprintf', `scanf', `fscanf',
- `sscanf', `strftime', `vprintf', `vfprintf' and `vsprintf'
- whenever such warnings are requested (using `-Wformat'), so there
- is no need to modify the header file `stdio.h'. In C99 mode, the
- functions `snprintf', `vsnprintf', `vscanf', `vfscanf' and
- `vsscanf' are also checked. Except in strictly conforming C
- standard modes, the X/Open function `strfmon' is also checked as
- are `printf_unlocked' and `fprintf_unlocked'. *Note Options
- Controlling C Dialect: C Dialect Options.
-
-`format_arg (STRING-INDEX)'
- The `format_arg' attribute specifies that a function takes a format
- string for a `printf', `scanf', `strftime' or `strfmon' style
- function and modifies it (for example, to translate it into
- another language), so the result can be passed to a `printf',
- `scanf', `strftime' or `strfmon' style function (with the
- remaining arguments to the format function the same as they would
- have been for the unmodified string). For example, the
- declaration:
-
- extern char *
- my_dgettext (char *my_domain, const char *my_format)
- __attribute__ ((format_arg (2)));
-
- causes the compiler to check the arguments in calls to a `printf',
- `scanf', `strftime' or `strfmon' type function, whose format
- string argument is a call to the `my_dgettext' function, for
- consistency with the format string argument `my_format'. If the
- `format_arg' attribute had not been specified, all the compiler
- could tell in such calls to format functions would be that the
- format string argument is not constant; this would generate a
- warning when `-Wformat-nonliteral' is used, but the calls could
- not be checked without the attribute.
-
- The parameter STRING-INDEX specifies which argument is the format
- string argument (starting from 1).
-
- The `format-arg' attribute allows you to identify your own
- functions which modify format strings, so that GCC can check the
- calls to `printf', `scanf', `strftime' or `strfmon' type function
- whose operands are a call to one of your own function. The
- compiler always treats `gettext', `dgettext', and `dcgettext' in
- this manner except when strict ISO C support is requested by
- `-ansi' or an appropriate `-std' option, or `-ffreestanding' is
- used. *Note Options Controlling C Dialect: C Dialect Options.
-
-`no_instrument_function'
- If `-finstrument-functions' is given, profiling function calls will
- be generated at entry and exit of most user-compiled functions.
- Functions with this attribute will not be so instrumented.
-
-`section ("SECTION-NAME")'
- Normally, the compiler places the code it generates in the `text'
- section. Sometimes, however, you need additional sections, or you
- need certain particular functions to appear in special sections.
- The `section' attribute specifies that a function lives in a
- particular section. For example, the declaration:
-
- extern void foobar (void) __attribute__ ((section ("bar")));
-
- puts the function `foobar' in the `bar' section.
-
- Some file formats do not support arbitrary sections so the
- `section' attribute is not available on all platforms. If you
- need to map the entire contents of a module to a particular
- section, consider using the facilities of the linker instead.
-
-`constructor'
-`destructor'
- The `constructor' attribute causes the function to be called
- automatically before execution enters `main ()'. Similarly, the
- `destructor' attribute causes the function to be called
- automatically after `main ()' has completed or `exit ()' has been
- called. Functions with these attributes are useful for
- initializing data that will be used implicitly during the
- execution of the program.
-
- These attributes are not currently implemented for Objective-C.
-
-`unused'
- This attribute, attached to a function, means that the function is
- meant to be possibly unused. GCC will not produce a warning for
- this function. GNU C++ does not currently support this attribute
- as definitions without parameters are valid in C++.
-
-`used'
- This attribute, attached to a function, means that code must be
- emitted for the function even if it appears that the function is
- not referenced. This is useful, for example, when the function is
- referenced only in inline assembly.
-
-`deprecated'
- The `deprecated' attribute results in a warning if the function is
- used anywhere in the source file. This is useful when identifying
- functions that are expected to be removed in a future version of a
- program. The warning also includes the location of the declaration
- of the deprecated function, to enable users to easily find further
- information about why the function is deprecated, or what they
- should do instead. Note that the warnings only occurs for uses:
-
- int old_fn () __attribute__ ((deprecated));
- int old_fn ();
- int (*fn_ptr)() = old_fn;
-
- results in a warning on line 3 but not line 2.
-
- The `deprecated' attribute can also be used for variables and
- types (*note Variable Attributes::, *note Type Attributes::.)
-
-`weak'
- The `weak' attribute causes the declaration to be emitted as a weak
- symbol rather than a global. This is primarily useful in defining
- library functions which can be overridden in user code, though it
- can also be used with non-function declarations. Weak symbols are
- supported for ELF targets, and also for a.out targets when using
- the GNU assembler and linker.
-
-`malloc'
- The `malloc' attribute is used to tell the compiler that a function
- may be treated as if it were the malloc function. The compiler
- assumes that calls to malloc result in a pointers that cannot
- alias anything. This will often improve optimization.
-
-`alias ("TARGET")'
- The `alias' attribute causes the declaration to be emitted as an
- alias for another symbol, which must be specified. For instance,
-
- void __f () { /* do something */; }
- void f () __attribute__ ((weak, alias ("__f")));
-
- declares `f' to be a weak alias for `__f'. In C++, the mangled
- name for the target must be used.
-
- Not all target machines support this attribute.
-
-`regparm (NUMBER)'
- On the Intel 386, the `regparm' attribute causes the compiler to
- pass up to NUMBER integer arguments in registers EAX, EDX, and ECX
- instead of on the stack. Functions that take a variable number of
- arguments will continue to be passed all of their arguments on the
- stack.
-
-`stdcall'
- On the Intel 386, the `stdcall' attribute causes the compiler to
- assume that the called function will pop off the stack space used
- to pass arguments, unless it takes a variable number of arguments.
-
- The PowerPC compiler for Windows NT currently ignores the `stdcall'
- attribute.
-
-`cdecl'
- On the Intel 386, the `cdecl' attribute causes the compiler to
- assume that the calling function will pop off the stack space used
- to pass arguments. This is useful to override the effects of the
- `-mrtd' switch.
-
- The PowerPC compiler for Windows NT currently ignores the `cdecl'
- attribute.
-
-`longcall'
- On the RS/6000 and PowerPC, the `longcall' attribute causes the
- compiler to always call the function via a pointer, so that
- functions which reside further than 64 megabytes (67,108,864
- bytes) from the current location can be called.
-
-`long_call/short_call'
- This attribute allows to specify how to call a particular function
- on ARM. Both attributes override the `-mlong-calls' (*note ARM
- Options::) command line switch and `#pragma long_calls' settings.
- The `long_call' attribute causes the compiler to always call the
- function by first loading its address into a register and then
- using the contents of that register. The `short_call' attribute
- always places the offset to the function from the call site into
- the `BL' instruction directly.
-
-`dllimport'
- On the PowerPC running Windows NT, the `dllimport' attribute causes
- the compiler to call the function via a global pointer to the
- function pointer that is set up by the Windows NT dll library.
- The pointer name is formed by combining `__imp_' and the function
- name.
-
-`dllexport'
- On the PowerPC running Windows NT, the `dllexport' attribute causes
- the compiler to provide a global pointer to the function pointer,
- so that it can be called with the `dllimport' attribute. The
- pointer name is formed by combining `__imp_' and the function name.
-
-`exception (EXCEPT-FUNC [, EXCEPT-ARG])'
- On the PowerPC running Windows NT, the `exception' attribute causes
- the compiler to modify the structured exception table entry it
- emits for the declared function. The string or identifier
- EXCEPT-FUNC is placed in the third entry of the structured
- exception table. It represents a function, which is called by the
- exception handling mechanism if an exception occurs. If it was
- specified, the string or identifier EXCEPT-ARG is placed in the
- fourth entry of the structured exception table.
-
-`function_vector'
- Use this attribute on the H8/300 and H8/300H to indicate that the
- specified function should be called through the function vector.
- Calling a function through the function vector will reduce code
- size, however; the function vector has a limited size (maximum 128
- entries on the H8/300 and 64 entries on the H8/300H) and shares
- space with the interrupt vector.
-
- You must use GAS and GLD from GNU binutils version 2.7 or later for
- this attribute to work correctly.
-
-`interrupt'
- Use this attribute on the ARM, AVR, M32R/D and Xstormy16 ports to
- indicate that the specified function is an interrupt handler. The
- compiler will generate function entry and exit sequences suitable
- for use in an interrupt handler when this attribute is present.
-
- Note, interrupt handlers for the H8/300, H8/300H and SH processors
- can be specified via the `interrupt_handler' attribute.
-
- Note, on the AVR interrupts will be enabled inside the function.
-
- Note, for the ARM you can specify the kind of interrupt to be
- handled by adding an optional parameter to the interrupt attribute
- like this:
-
- void f () __attribute__ ((interrupt ("IRQ")));
-
- Permissible values for this parameter are: IRQ, FIQ, SWI, ABORT
- and UNDEF.
-
-`interrupt_handler'
- Use this attribute on the H8/300, H8/300H and SH to indicate that
- the specified function is an interrupt handler. The compiler will
- generate function entry and exit sequences suitable for use in an
- interrupt handler when this attribute is present.
-
-`sp_switch'
- Use this attribute on the SH to indicate an `interrupt_handler'
- function should switch to an alternate stack. It expects a string
- argument that names a global variable holding the address of the
- alternate stack.
-
- void *alt_stack;
- void f () __attribute__ ((interrupt_handler,
- sp_switch ("alt_stack")));
-
-`trap_exit'
- Use this attribute on the SH for an `interrupt_handle' to return
- using `trapa' instead of `rte'. This attribute expects an integer
- argument specifying the trap number to be used.
-
-`eightbit_data'
- Use this attribute on the H8/300 and H8/300H to indicate that the
- specified variable should be placed into the eight bit data
- section. The compiler will generate more efficient code for
- certain operations on data in the eight bit data area. Note the
- eight bit data area is limited to 256 bytes of data.
-
- You must use GAS and GLD from GNU binutils version 2.7 or later for
- this attribute to work correctly.
-
-`tiny_data'
- Use this attribute on the H8/300H to indicate that the specified
- variable should be placed into the tiny data section. The
- compiler will generate more efficient code for loads and stores on
- data in the tiny data section. Note the tiny data area is limited
- to slightly under 32kbytes of data.
-
-`signal'
- Use this attribute on the AVR to indicate that the specified
- function is an signal handler. The compiler will generate function
- entry and exit sequences suitable for use in an signal handler
- when this attribute is present. Interrupts will be disabled
- inside function.
-
-`naked'
- Use this attribute on the ARM or AVR ports to indicate that the
- specified function do not need prologue/epilogue sequences
- generated by the compiler. It is up to the programmer to provide
- these sequences.
-
-`model (MODEL-NAME)'
- Use this attribute on the M32R/D to set the addressability of an
- object, and the code generated for a function. The identifier
- MODEL-NAME is one of `small', `medium', or `large', representing
- each of the code models.
-
- Small model objects live in the lower 16MB of memory (so that their
- addresses can be loaded with the `ld24' instruction), and are
- callable with the `bl' instruction.
-
- Medium model objects may live anywhere in the 32-bit address space
- (the compiler will generate `seth/add3' instructions to load their
- addresses), and are callable with the `bl' instruction.
-
- Large model objects may live anywhere in the 32-bit address space
- (the compiler will generate `seth/add3' instructions to load their
- addresses), and may not be reachable with the `bl' instruction
- (the compiler will generate the much slower `seth/add3/jl'
- instruction sequence).
-
-
- You can specify multiple attributes in a declaration by separating
-them by commas within the double parentheses or by immediately
-following an attribute declaration with another attribute declaration.
-
- Some people object to the `__attribute__' feature, suggesting that
-ISO C's `#pragma' should be used instead. At the time `__attribute__'
-was designed, there were two reasons for not doing this.
-
- 1. It is impossible to generate `#pragma' commands from a macro.
-
- 2. There is no telling what the same `#pragma' might mean in another
- compiler.
-
- These two reasons applied to almost any application that might have
-been proposed for `#pragma'. It was basically a mistake to use
-`#pragma' for _anything_.
-
- The ISO C99 standard includes `_Pragma', which now allows pragmas to
-be generated from macros. In addition, a `#pragma GCC' namespace is
-now in use for GCC-specific pragmas. However, it has been found
-convenient to use `__attribute__' to achieve a natural attachment of
-attributes to their corresponding declarations, whereas `#pragma GCC'
-is of use for constructs that do not naturally form part of the
-grammar. *Note Miscellaneous Preprocessing Directives: (cpp)Other
-Directives.
-
-\1f
-File: gcc.info, Node: Attribute Syntax, Next: Function Prototypes, Prev: Function Attributes, Up: C Extensions
-
-Attribute Syntax
-================
-
- This section describes the syntax with which `__attribute__' may be
-used, and the constructs to which attribute specifiers bind, for the C
-language. Some details may vary for C++ and Objective-C. Because of
-infelicities in the grammar for attributes, some forms described here
-may not be successfully parsed in all cases.
-
- There are some problems with the semantics of attributes in C++. For
-example, there are no manglings for attributes, although they may affect
-code generation, so problems may arise when attributed types are used in
-conjunction with templates or overloading. Similarly, `typeid' does
-not distinguish between types with different attributes. Support for
-attributes in C++ may be restricted in future to attributes on
-declarations only, but not on nested declarators.
-
- *Note Function Attributes::, for details of the semantics of
-attributes applying to functions. *Note Variable Attributes::, for
-details of the semantics of attributes applying to variables. *Note
-Type Attributes::, for details of the semantics of attributes applying
-to structure, union and enumerated types.
-
- An "attribute specifier" is of the form `__attribute__
-((ATTRIBUTE-LIST))'. An "attribute list" is a possibly empty
-comma-separated sequence of "attributes", where each attribute is one
-of the following:
-
- * Empty. Empty attributes are ignored.
-
- * A word (which may be an identifier such as `unused', or a reserved
- word such as `const').
-
- * A word, followed by, in parentheses, parameters for the attribute.
- These parameters take one of the following forms:
-
- * An identifier. For example, `mode' attributes use this form.
-
- * An identifier followed by a comma and a non-empty
- comma-separated list of expressions. For example, `format'
- attributes use this form.
-
- * A possibly empty comma-separated list of expressions. For
- example, `format_arg' attributes use this form with the list
- being a single integer constant expression, and `alias'
- attributes use this form with the list being a single string
- constant.
-
- An "attribute specifier list" is a sequence of one or more attribute
-specifiers, not separated by any other tokens.
-
- An attribute specifier list may appear after the colon following a
-label, other than a `case' or `default' label. The only attribute it
-makes sense to use after a label is `unused'. This feature is intended
-for code generated by programs which contains labels that may be unused
-but which is compiled with `-Wall'. It would not normally be
-appropriate to use in it human-written code, though it could be useful
-in cases where the code that jumps to the label is contained within an
-`#ifdef' conditional.
-
- An attribute specifier list may appear as part of a `struct',
-`union' or `enum' specifier. It may go either immediately after the
-`struct', `union' or `enum' keyword, or after the closing brace. It is
-ignored if the content of the structure, union or enumerated type is
-not defined in the specifier in which the attribute specifier list is
-used--that is, in usages such as `struct __attribute__((foo)) bar' with
-no following opening brace. Where attribute specifiers follow the
-closing brace, they are considered to relate to the structure, union or
-enumerated type defined, not to any enclosing declaration the type
-specifier appears in, and the type defined is not complete until after
-the attribute specifiers.
-
- Otherwise, an attribute specifier appears as part of a declaration,
-counting declarations of unnamed parameters and type names, and relates
-to that declaration (which may be nested in another declaration, for
-example in the case of a parameter declaration), or to a particular
-declarator within a declaration. Where an attribute specifier is
-applied to a parameter declared as a function or an array, it should
-apply to the function or array rather than the pointer to which the
-parameter is implicitly converted, but this is not yet correctly
-implemented.
-
- Any list of specifiers and qualifiers at the start of a declaration
-may contain attribute specifiers, whether or not such a list may in that
-context contain storage class specifiers. (Some attributes, however,
-are essentially in the nature of storage class specifiers, and only make
-sense where storage class specifiers may be used; for example,
-`section'.) There is one necessary limitation to this syntax: the
-first old-style parameter declaration in a function definition cannot
-begin with an attribute specifier, because such an attribute applies to
-the function instead by syntax described below (which, however, is not
-yet implemented in this case). In some other cases, attribute
-specifiers are permitted by this grammar but not yet supported by the
-compiler. All attribute specifiers in this place relate to the
-declaration as a whole. In the obsolescent usage where a type of `int'
-is implied by the absence of type specifiers, such a list of specifiers
-and qualifiers may be an attribute specifier list with no other
-specifiers or qualifiers.
-
- An attribute specifier list may appear immediately before a
-declarator (other than the first) in a comma-separated list of
-declarators in a declaration of more than one identifier using a single
-list of specifiers and qualifiers. Such attribute specifiers apply
-only to the identifier before whose declarator they appear. For
-example, in
-
- __attribute__((noreturn)) void d0 (void),
- __attribute__((format(printf, 1, 2))) d1 (const char *, ...),
- d2 (void)
-
-the `noreturn' attribute applies to all the functions declared; the
-`format' attribute only applies to `d1'.
-
- An attribute specifier list may appear immediately before the comma,
-`=' or semicolon terminating the declaration of an identifier other
-than a function definition. At present, such attribute specifiers apply
-to the declared object or function, but in future they may attach to the
-outermost adjacent declarator. In simple cases there is no difference,
-but, for example, in
-
- void (****f)(void) __attribute__((noreturn));
-
-at present the `noreturn' attribute applies to `f', which causes a
-warning since `f' is not a function, but in future it may apply to the
-function `****f'. The precise semantics of what attributes in such
-cases will apply to are not yet specified. Where an assembler name for
-an object or function is specified (*note Asm Labels::), at present the
-attribute must follow the `asm' specification; in future, attributes
-before the `asm' specification may apply to the adjacent declarator,
-and those after it to the declared object or function.
-
- An attribute specifier list may, in future, be permitted to appear
-after the declarator in a function definition (before any old-style
-parameter declarations or the function body).
-
- Attribute specifiers may be mixed with type qualifiers appearing
-inside the `[]' of a parameter array declarator, in the C99 construct by
-which such qualifiers are applied to the pointer to which the array is
-implicitly converted. Such attribute specifiers apply to the pointer,
-not to the array, but at present this is not implemented and they are
-ignored.
-
- An attribute specifier list may appear at the start of a nested
-declarator. At present, there are some limitations in this usage: the
-attributes correctly apply to the declarator, but for most individual
-attributes the semantics this implies are not implemented. When
-attribute specifiers follow the `*' of a pointer declarator, they may
-be mixed with any type qualifiers present. The following describes the
-formal semantics of this syntax. It will make the most sense if you
-are familiar with the formal specification of declarators in the ISO C
-standard.
-
- Consider (as in C99 subclause 6.7.5 paragraph 4) a declaration `T
-D1', where `T' contains declaration specifiers that specify a type TYPE
-(such as `int') and `D1' is a declarator that contains an identifier
-IDENT. The type specified for IDENT for derived declarators whose type
-does not include an attribute specifier is as in the ISO C standard.
-
- If `D1' has the form `( ATTRIBUTE-SPECIFIER-LIST D )', and the
-declaration `T D' specifies the type "DERIVED-DECLARATOR-TYPE-LIST
-TYPE" for IDENT, then `T D1' specifies the type
-"DERIVED-DECLARATOR-TYPE-LIST ATTRIBUTE-SPECIFIER-LIST TYPE" for IDENT.
-
- If `D1' has the form `* TYPE-QUALIFIER-AND-ATTRIBUTE-SPECIFIER-LIST
-D', and the declaration `T D' specifies the type
-"DERIVED-DECLARATOR-TYPE-LIST TYPE" for IDENT, then `T D1' specifies
-the type "DERIVED-DECLARATOR-TYPE-LIST
-TYPE-QUALIFIER-AND-ATTRIBUTE-SPECIFIER-LIST TYPE" for IDENT.
-
- For example,
-
- void (__attribute__((noreturn)) ****f) (void);
-
-specifies the type "pointer to pointer to pointer to pointer to
-non-returning function returning `void'". As another example,
-
- char *__attribute__((aligned(8))) *f;
-
-specifies the type "pointer to 8-byte-aligned pointer to `char'". Note
-again that this does not work with most attributes; for example, the
-usage of `aligned' and `noreturn' attributes given above is not yet
-supported.
-
- For compatibility with existing code written for compiler versions
-that did not implement attributes on nested declarators, some laxity is
-allowed in the placing of attributes. If an attribute that only applies
-to types is applied to a declaration, it will be treated as applying to
-the type of that declaration. If an attribute that only applies to
-declarations is applied to the type of a declaration, it will be treated
-as applying to that declaration; and, for compatibility with code
-placing the attributes immediately before the identifier declared, such
-an attribute applied to a function return type will be treated as
-applying to the function type, and such an attribute applied to an array
-element type will be treated as applying to the array type. If an
-attribute that only applies to function types is applied to a
-pointer-to-function type, it will be treated as applying to the pointer
-target type; if such an attribute is applied to a function return type
-that is not a pointer-to-function type, it will be treated as applying
-to the function type.
-
-\1f
-File: gcc.info, Node: Function Prototypes, Next: C++ Comments, Prev: Attribute Syntax, Up: C Extensions
-
-Prototypes and Old-Style Function Definitions
-=============================================
-
- GNU C extends ISO C to allow a function prototype to override a later
-old-style non-prototype definition. Consider the following example:
-
- /* Use prototypes unless the compiler is old-fashioned. */
- #ifdef __STDC__
- #define P(x) x
- #else
- #define P(x) ()
- #endif
-
- /* Prototype function declaration. */
- int isroot P((uid_t));
-
- /* Old-style function definition. */
- int
- isroot (x) /* ??? lossage here ??? */
- uid_t x;
- {
- return x == 0;
- }
-
- Suppose the type `uid_t' happens to be `short'. ISO C does not
-allow this example, because subword arguments in old-style
-non-prototype definitions are promoted. Therefore in this example the
-function definition's argument is really an `int', which does not match
-the prototype argument type of `short'.
-
- This restriction of ISO C makes it hard to write code that is
-portable to traditional C compilers, because the programmer does not
-know whether the `uid_t' type is `short', `int', or `long'. Therefore,
-in cases like these GNU C allows a prototype to override a later
-old-style definition. More precisely, in GNU C, a function prototype
-argument type overrides the argument type specified by a later
-old-style definition if the former type is the same as the latter type
-before promotion. Thus in GNU C the above example is equivalent to the
-following:
-
- int isroot (uid_t);
-
- int
- isroot (uid_t x)
- {
- return x == 0;
- }
-
-GNU C++ does not support old-style function definitions, so this
-extension is irrelevant.
-
-\1f
-File: gcc.info, Node: C++ Comments, Next: Dollar Signs, Prev: Function Prototypes, Up: C Extensions
-
-C++ Style Comments
-==================
-
- In GNU C, you may use C++ style comments, which start with `//' and
-continue until the end of the line. Many other C implementations allow
-such comments, and they are likely to be in a future C standard.
-However, C++ style comments are not recognized if you specify `-ansi',
-a `-std' option specifying a version of ISO C before C99, or
-`-traditional', since they are incompatible with traditional constructs
-like `dividend//*comment*/divisor'.
-
-\1f
-File: gcc.info, Node: Dollar Signs, Next: Character Escapes, Prev: C++ Comments, Up: C Extensions
-
-Dollar Signs in Identifier Names
-================================
-
- In GNU C, you may normally use dollar signs in identifier names.
-This is because many traditional C implementations allow such
-identifiers. However, dollar signs in identifiers are not supported on
-a few target machines, typically because the target assembler does not
-allow them.
-
-\1f
-File: gcc.info, Node: Character Escapes, Next: Variable Attributes, Prev: Dollar Signs, Up: C Extensions
-
-The Character <ESC> in Constants
-================================
-
- You can use the sequence `\e' in a string or character constant to
-stand for the ASCII character <ESC>.
-
-\1f
-File: gcc.info, Node: Alignment, Next: Inline, Prev: Type Attributes, Up: C Extensions
-
-Inquiring on Alignment of Types or Variables
-============================================
-
- The keyword `__alignof__' allows you to inquire about how an object
-is aligned, or the minimum alignment usually required by a type. Its
-syntax is just like `sizeof'.
-
- For example, if the target machine requires a `double' value to be
-aligned on an 8-byte boundary, then `__alignof__ (double)' is 8. This
-is true on many RISC machines. On more traditional machine designs,
-`__alignof__ (double)' is 4 or even 2.
-
- Some machines never actually require alignment; they allow reference
-to any data type even at an odd addresses. For these machines,
-`__alignof__' reports the _recommended_ alignment of a type.
-
- If the operand of `__alignof__' is an lvalue rather than a type, its
-value is the required alignment for its type, taking into account any
-minimum alignment specified with GCC's `__attribute__' extension (*note
-Variable Attributes::). For example, after this declaration:
-
- struct foo { int x; char y; } foo1;
-
-the value of `__alignof__ (foo1.y)' is 1, even though its actual
-alignment is probably 2 or 4, the same as `__alignof__ (int)'.
-
- It is an error to ask for the alignment of an incomplete type.
-
-\1f
-File: gcc.info, Node: Variable Attributes, Next: Type Attributes, Prev: Character Escapes, Up: C Extensions
-
-Specifying Attributes of Variables
-==================================
-
- The keyword `__attribute__' allows you to specify special attributes
-of variables or structure fields. This keyword is followed by an
-attribute specification inside double parentheses. Ten attributes are
-currently defined for variables: `aligned', `mode', `nocommon',
-`packed', `section', `transparent_union', `unused', `deprecated',
-`vector_size', and `weak'. Some other attributes are defined for
-variables on particular target systems. Other attributes are available
-for functions (*note Function Attributes::) and for types (*note Type
-Attributes::). Other front ends might define more attributes (*note
-Extensions to the C++ Language: C++ Extensions.).
-
- You may also specify attributes with `__' preceding and following
-each keyword. This allows you to use them in header files without
-being concerned about a possible macro of the same name. For example,
-you may use `__aligned__' instead of `aligned'.
-
- *Note Attribute Syntax::, for details of the exact syntax for using
-attributes.
-
-`aligned (ALIGNMENT)'
- This attribute specifies a minimum alignment for the variable or
- structure field, measured in bytes. For example, the declaration:
-
- int x __attribute__ ((aligned (16))) = 0;
-
- causes the compiler to allocate the global variable `x' on a
- 16-byte boundary. On a 68040, this could be used in conjunction
- with an `asm' expression to access the `move16' instruction which
- requires 16-byte aligned operands.
-
- You can also specify the alignment of structure fields. For
- example, to create a double-word aligned `int' pair, you could
- write:
-
- struct foo { int x[2] __attribute__ ((aligned (8))); };
-
- This is an alternative to creating a union with a `double' member
- that forces the union to be double-word aligned.
-
- As in the preceding examples, you can explicitly specify the
- alignment (in bytes) that you wish the compiler to use for a given
- variable or structure field. Alternatively, you can leave out the
- alignment factor and just ask the compiler to align a variable or
- field to the maximum useful alignment for the target machine you
- are compiling for. For example, you could write:
-
- short array[3] __attribute__ ((aligned));
-
- Whenever you leave out the alignment factor in an `aligned'
- attribute specification, the compiler automatically sets the
- alignment for the declared variable or field to the largest
- alignment which is ever used for any data type on the target
- machine you are compiling for. Doing this can often make copy
- operations more efficient, because the compiler can use whatever
- instructions copy the biggest chunks of memory when performing
- copies to or from the variables or fields that you have aligned
- this way.
-
- The `aligned' attribute can only increase the alignment; but you
- can decrease it by specifying `packed' as well. See below.
-
- Note that the effectiveness of `aligned' attributes may be limited
- by inherent limitations in your linker. On many systems, the
- linker is only able to arrange for variables to be aligned up to a
- certain maximum alignment. (For some linkers, the maximum
- supported alignment may be very very small.) If your linker is
- only able to align variables up to a maximum of 8 byte alignment,
- then specifying `aligned(16)' in an `__attribute__' will still
- only provide you with 8 byte alignment. See your linker
- documentation for further information.
-
-`mode (MODE)'
- This attribute specifies the data type for the
- declaration--whichever type corresponds to the mode MODE. This in
- effect lets you request an integer or floating point type
- according to its width.
-
- You may also specify a mode of `byte' or `__byte__' to indicate
- the mode corresponding to a one-byte integer, `word' or `__word__'
- for the mode of a one-word integer, and `pointer' or `__pointer__'
- for the mode used to represent pointers.
-
-`nocommon'
- This attribute specifies requests GCC not to place a variable
- "common" but instead to allocate space for it directly. If you
- specify the `-fno-common' flag, GCC will do this for all variables.
-
- Specifying the `nocommon' attribute for a variable provides an
- initialization of zeros. A variable may only be initialized in one
- source file.
-
-`packed'
- The `packed' attribute specifies that a variable or structure field
- should have the smallest possible alignment--one byte for a
- variable, and one bit for a field, unless you specify a larger
- value with the `aligned' attribute.
-
- Here is a structure in which the field `x' is packed, so that it
- immediately follows `a':
-
- struct foo
- {
- char a;
- int x[2] __attribute__ ((packed));
- };
-
-`section ("SECTION-NAME")'
- Normally, the compiler places the objects it generates in sections
- like `data' and `bss'. Sometimes, however, you need additional
- sections, or you need certain particular variables to appear in
- special sections, for example to map to special hardware. The
- `section' attribute specifies that a variable (or function) lives
- in a particular section. For example, this small program uses
- several specific section names:
-
- struct duart a __attribute__ ((section ("DUART_A"))) = { 0 };
- struct duart b __attribute__ ((section ("DUART_B"))) = { 0 };
- char stack[10000] __attribute__ ((section ("STACK"))) = { 0 };
- int init_data __attribute__ ((section ("INITDATA"))) = 0;
-
- main()
- {
- /* Initialize stack pointer */
- init_sp (stack + sizeof (stack));
-
- /* Initialize initialized data */
- memcpy (&init_data, &data, &edata - &data);
-
- /* Turn on the serial ports */
- init_duart (&a);
- init_duart (&b);
- }
-
- Use the `section' attribute with an _initialized_ definition of a
- _global_ variable, as shown in the example. GCC issues a warning
- and otherwise ignores the `section' attribute in uninitialized
- variable declarations.
-
- You may only use the `section' attribute with a fully initialized
- global definition because of the way linkers work. The linker
- requires each object be defined once, with the exception that
- uninitialized variables tentatively go in the `common' (or `bss')
- section and can be multiply "defined". You can force a variable
- to be initialized with the `-fno-common' flag or the `nocommon'
- attribute.
-
- Some file formats do not support arbitrary sections so the
- `section' attribute is not available on all platforms. If you
- need to map the entire contents of a module to a particular
- section, consider using the facilities of the linker instead.
-
-`shared'
- On Windows NT, in addition to putting variable definitions in a
- named section, the section can also be shared among all running
- copies of an executable or DLL. For example, this small program
- defines shared data by putting it in a named section `shared' and
- marking the section shareable:
-
- int foo __attribute__((section ("shared"), shared)) = 0;
-
- int
- main()
- {
- /* Read and write foo. All running
- copies see the same value. */
- return 0;
- }
-
- You may only use the `shared' attribute along with `section'
- attribute with a fully initialized global definition because of
- the way linkers work. See `section' attribute for more
- information.
-
- The `shared' attribute is only available on Windows NT.
-
-`transparent_union'
- This attribute, attached to a function parameter which is a union,
- means that the corresponding argument may have the type of any
- union member, but the argument is passed as if its type were that
- of the first union member. For more details see *Note Type
- Attributes::. You can also use this attribute on a `typedef' for
- a union data type; then it applies to all function parameters with
- that type.
-
-`unused'
- This attribute, attached to a variable, means that the variable is
- meant to be possibly unused. GCC will not produce a warning for
- this variable.
-
-`deprecated'
- The `deprecated' attribute results in a warning if the variable is
- used anywhere in the source file. This is useful when identifying
- variables that are expected to be removed in a future version of a
- program. The warning also includes the location of the declaration
- of the deprecated variable, to enable users to easily find further
- information about why the variable is deprecated, or what they
- should do instead. Note that the warnings only occurs for uses:
-
- extern int old_var __attribute__ ((deprecated));
- extern int old_var;
- int new_fn () { return old_var; }
-
- results in a warning on line 3 but not line 2.
-
- The `deprecated' attribute can also be used for functions and
- types (*note Function Attributes::, *note Type Attributes::.)
-
-`vector_size (BYTES)'
- This attribute specifies the vector size for the variable,
- measured in bytes. For example, the declaration:
-
- int foo __attribute__ ((vector_size (16)));
-
- causes the compiler to set the mode for `foo', to be 16 bytes,
- divided into `int' sized units. Assuming a 32-bit int (a vector of
- 4 units of 4 bytes), the corresponding mode of `foo' will be V4SI.
-
- This attribute is only applicable to integral and float scalars,
- although arrays, pointers, and function return values are allowed
- in conjunction with this construct.
-
- Aggregates with this attribute are invalid, even if they are of
- the same size as a corresponding scalar. For example, the
- declaration:
-
- struct S { int a; };
- struct S __attribute__ ((vector_size (16))) foo;
-
- is invalid even if the size of the structure is the same as the
- size of the `int'.
-
-`weak'
- The `weak' attribute is described in *Note Function Attributes::.
-
-`model (MODEL-NAME)'
- Use this attribute on the M32R/D to set the addressability of an
- object. The identifier MODEL-NAME is one of `small', `medium', or
- `large', representing each of the code models.
-
- Small model objects live in the lower 16MB of memory (so that their
- addresses can be loaded with the `ld24' instruction).
-
- Medium and large model objects may live anywhere in the 32-bit
- address space (the compiler will generate `seth/add3' instructions
- to load their addresses).
-
-
- To specify multiple attributes, separate them by commas within the
-double parentheses: for example, `__attribute__ ((aligned (16),
-packed))'.
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Type Attributes, Next: Alignment, Prev: Variable Attributes, Up: C Extensions
-
-Specifying Attributes of Types
-==============================
-
- The keyword `__attribute__' allows you to specify special attributes
-of `struct' and `union' types when you define such types. This keyword
-is followed by an attribute specification inside double parentheses.
-Five attributes are currently defined for types: `aligned', `packed',
-`transparent_union', `unused', and `deprecated'. Other attributes are
-defined for functions (*note Function Attributes::) and for variables
-(*note Variable Attributes::).
-
- You may also specify any one of these attributes with `__' preceding
-and following its keyword. This allows you to use these attributes in
-header files without being concerned about a possible macro of the same
-name. For example, you may use `__aligned__' instead of `aligned'.
-
- You may specify the `aligned' and `transparent_union' attributes
-either in a `typedef' declaration or just past the closing curly brace
-of a complete enum, struct or union type _definition_ and the `packed'
-attribute only past the closing brace of a definition.
-
- You may also specify attributes between the enum, struct or union
-tag and the name of the type rather than after the closing brace.
-
- *Note Attribute Syntax::, for details of the exact syntax for using
-attributes.
-
-`aligned (ALIGNMENT)'
- This attribute specifies a minimum alignment (in bytes) for
- variables of the specified type. For example, the declarations:
-
- struct S { short f[3]; } __attribute__ ((aligned (8)));
- typedef int more_aligned_int __attribute__ ((aligned (8)));
-
- force the compiler to insure (as far as it can) that each variable
- whose type is `struct S' or `more_aligned_int' will be allocated
- and aligned _at least_ on a 8-byte boundary. On a Sparc, having
- all variables of type `struct S' aligned to 8-byte boundaries
- allows the compiler to use the `ldd' and `std' (doubleword load and
- store) instructions when copying one variable of type `struct S' to
- another, thus improving run-time efficiency.
-
- Note that the alignment of any given `struct' or `union' type is
- required by the ISO C standard to be at least a perfect multiple of
- the lowest common multiple of the alignments of all of the members
- of the `struct' or `union' in question. This means that you _can_
- effectively adjust the alignment of a `struct' or `union' type by
- attaching an `aligned' attribute to any one of the members of such
- a type, but the notation illustrated in the example above is a
- more obvious, intuitive, and readable way to request the compiler
- to adjust the alignment of an entire `struct' or `union' type.
-
- As in the preceding example, you can explicitly specify the
- alignment (in bytes) that you wish the compiler to use for a given
- `struct' or `union' type. Alternatively, you can leave out the
- alignment factor and just ask the compiler to align a type to the
- maximum useful alignment for the target machine you are compiling
- for. For example, you could write:
-
- struct S { short f[3]; } __attribute__ ((aligned));
-
- Whenever you leave out the alignment factor in an `aligned'
- attribute specification, the compiler automatically sets the
- alignment for the type to the largest alignment which is ever used
- for any data type on the target machine you are compiling for.
- Doing this can often make copy operations more efficient, because
- the compiler can use whatever instructions copy the biggest chunks
- of memory when performing copies to or from the variables which
- have types that you have aligned this way.
-
- In the example above, if the size of each `short' is 2 bytes, then
- the size of the entire `struct S' type is 6 bytes. The smallest
- power of two which is greater than or equal to that is 8, so the
- compiler sets the alignment for the entire `struct S' type to 8
- bytes.
-
- Note that although you can ask the compiler to select a
- time-efficient alignment for a given type and then declare only
- individual stand-alone objects of that type, the compiler's
- ability to select a time-efficient alignment is primarily useful
- only when you plan to create arrays of variables having the
- relevant (efficiently aligned) type. If you declare or use arrays
- of variables of an efficiently-aligned type, then it is likely
- that your program will also be doing pointer arithmetic (or
- subscripting, which amounts to the same thing) on pointers to the
- relevant type, and the code that the compiler generates for these
- pointer arithmetic operations will often be more efficient for
- efficiently-aligned types than for other types.
-
- The `aligned' attribute can only increase the alignment; but you
- can decrease it by specifying `packed' as well. See below.
-
- Note that the effectiveness of `aligned' attributes may be limited
- by inherent limitations in your linker. On many systems, the
- linker is only able to arrange for variables to be aligned up to a
- certain maximum alignment. (For some linkers, the maximum
- supported alignment may be very very small.) If your linker is
- only able to align variables up to a maximum of 8 byte alignment,
- then specifying `aligned(16)' in an `__attribute__' will still
- only provide you with 8 byte alignment. See your linker
- documentation for further information.
-
-`packed'
- This attribute, attached to an `enum', `struct', or `union' type
- definition, specified that the minimum required memory be used to
- represent the type.
-
- Specifying this attribute for `struct' and `union' types is
- equivalent to specifying the `packed' attribute on each of the
- structure or union members. Specifying the `-fshort-enums' flag
- on the line is equivalent to specifying the `packed' attribute on
- all `enum' definitions.
-
- You may only specify this attribute after a closing curly brace on
- an `enum' definition, not in a `typedef' declaration, unless that
- declaration also contains the definition of the `enum'.
-
-`transparent_union'
- This attribute, attached to a `union' type definition, indicates
- that any function parameter having that union type causes calls to
- that function to be treated in a special way.
-
- First, the argument corresponding to a transparent union type can
- be of any type in the union; no cast is required. Also, if the
- union contains a pointer type, the corresponding argument can be a
- null pointer constant or a void pointer expression; and if the
- union contains a void pointer type, the corresponding argument can
- be any pointer expression. If the union member type is a pointer,
- qualifiers like `const' on the referenced type must be respected,
- just as with normal pointer conversions.
-
- Second, the argument is passed to the function using the calling
- conventions of first member of the transparent union, not the
- calling conventions of the union itself. All members of the union
- must have the same machine representation; this is necessary for
- this argument passing to work properly.
-
- Transparent unions are designed for library functions that have
- multiple interfaces for compatibility reasons. For example,
- suppose the `wait' function must accept either a value of type
- `int *' to comply with Posix, or a value of type `union wait *' to
- comply with the 4.1BSD interface. If `wait''s parameter were
- `void *', `wait' would accept both kinds of arguments, but it
- would also accept any other pointer type and this would make
- argument type checking less useful. Instead, `<sys/wait.h>' might
- define the interface as follows:
-
- typedef union
- {
- int *__ip;
- union wait *__up;
- } wait_status_ptr_t __attribute__ ((__transparent_union__));
-
- pid_t wait (wait_status_ptr_t);
-
- This interface allows either `int *' or `union wait *' arguments
- to be passed, using the `int *' calling convention. The program
- can call `wait' with arguments of either type:
-
- int w1 () { int w; return wait (&w); }
- int w2 () { union wait w; return wait (&w); }
-
- With this interface, `wait''s implementation might look like this:
-
- pid_t wait (wait_status_ptr_t p)
- {
- return waitpid (-1, p.__ip, 0);
- }
-
-`unused'
- When attached to a type (including a `union' or a `struct'), this
- attribute means that variables of that type are meant to appear
- possibly unused. GCC will not produce a warning for any variables
- of that type, even if the variable appears to do nothing. This is
- often the case with lock or thread classes, which are usually
- defined and then not referenced, but contain constructors and
- destructors that have nontrivial bookkeeping functions.
-
-`deprecated'
- The `deprecated' attribute results in a warning if the type is
- used anywhere in the source file. This is useful when identifying
- types that are expected to be removed in a future version of a
- program. If possible, the warning also includes the location of
- the declaration of the deprecated type, to enable users to easily
- find further information about why the type is deprecated, or what
- they should do instead. Note that the warnings only occur for
- uses and then only if the type is being applied to an identifier
- that itself is not being declared as deprecated.
-
- typedef int T1 __attribute__ ((deprecated));
- T1 x;
- typedef T1 T2;
- T2 y;
- typedef T1 T3 __attribute__ ((deprecated));
- T3 z __attribute__ ((deprecated));
-
- results in a warning on line 2 and 3 but not lines 4, 5, or 6. No
- warning is issued for line 4 because T2 is not explicitly
- deprecated. Line 5 has no warning because T3 is explicitly
- deprecated. Similarly for line 6.
-
- The `deprecated' attribute can also be used for functions and
- variables (*note Function Attributes::, *note Variable
- Attributes::.)
-
-
- To specify multiple attributes, separate them by commas within the
-double parentheses: for example, `__attribute__ ((aligned (16),
-packed))'.
-
-\1f
-File: gcc.info, Node: Inline, Next: Extended Asm, Prev: Alignment, Up: C Extensions
-
-An Inline Function is As Fast As a Macro
-========================================
-
- By declaring a function `inline', you can direct GCC to integrate
-that function's code into the code for its callers. This makes
-execution faster by eliminating the function-call overhead; in
-addition, if any of the actual argument values are constant, their known
-values may permit simplifications at compile time so that not all of the
-inline function's code needs to be included. The effect on code size is
-less predictable; object code may be larger or smaller with function
-inlining, depending on the particular case. Inlining of functions is an
-optimization and it really "works" only in optimizing compilation. If
-you don't use `-O', no function is really inline.
-
- Inline functions are included in the ISO C99 standard, but there are
-currently substantial differences between what GCC implements and what
-the ISO C99 standard requires.
-
- To declare a function inline, use the `inline' keyword in its
-declaration, like this:
-
- inline int
- inc (int *a)
- {
- (*a)++;
- }
-
- (If you are writing a header file to be included in ISO C programs,
-write `__inline__' instead of `inline'. *Note Alternate Keywords::.)
-You can also make all "simple enough" functions inline with the option
-`-finline-functions'.
-
- Note that certain usages in a function definition can make it
-unsuitable for inline substitution. Among these usages are: use of
-varargs, use of alloca, use of variable sized data types (*note
-Variable Length::), use of computed goto (*note Labels as Values::),
-use of nonlocal goto, and nested functions (*note Nested Functions::).
-Using `-Winline' will warn when a function marked `inline' could not be
-substituted, and will give the reason for the failure.
-
- Note that in C and Objective-C, unlike C++, the `inline' keyword
-does not affect the linkage of the function.
-
- GCC automatically inlines member functions defined within the class
-body of C++ programs even if they are not explicitly declared `inline'.
-(You can override this with `-fno-default-inline'; *note Options
-Controlling C++ Dialect: C++ Dialect Options..)
-
- When a function is both inline and `static', if all calls to the
-function are integrated into the caller, and the function's address is
-never used, then the function's own assembler code is never referenced.
-In this case, GCC does not actually output assembler code for the
-function, unless you specify the option `-fkeep-inline-functions'.
-Some calls cannot be integrated for various reasons (in particular,
-calls that precede the function's definition cannot be integrated, and
-neither can recursive calls within the definition). If there is a
-nonintegrated call, then the function is compiled to assembler code as
-usual. The function must also be compiled as usual if the program
-refers to its address, because that can't be inlined.
-
- When an inline function is not `static', then the compiler must
-assume that there may be calls from other source files; since a global
-symbol can be defined only once in any program, the function must not
-be defined in the other source files, so the calls therein cannot be
-integrated. Therefore, a non-`static' inline function is always
-compiled on its own in the usual fashion.
-
- If you specify both `inline' and `extern' in the function
-definition, then the definition is used only for inlining. In no case
-is the function compiled on its own, not even if you refer to its
-address explicitly. Such an address becomes an external reference, as
-if you had only declared the function, and had not defined it.
-
- This combination of `inline' and `extern' has almost the effect of a
-macro. The way to use it is to put a function definition in a header
-file with these keywords, and put another copy of the definition
-(lacking `inline' and `extern') in a library file. The definition in
-the header file will cause most calls to the function to be inlined.
-If any uses of the function remain, they will refer to the single copy
-in the library.
-
- For future compatibility with when GCC implements ISO C99 semantics
-for inline functions, it is best to use `static inline' only. (The
-existing semantics will remain available when `-std=gnu89' is
-specified, but eventually the default will be `-std=gnu99' and that
-will implement the C99 semantics, though it does not do so yet.)
-
- GCC does not inline any functions when not optimizing unless you
-specify the `always_inline' attribute for the function, like this:
-
- /* Prototype. */
- inline void foo (const char) __attribute__((always_inline));
-
-\1f
-File: gcc.info, Node: Extended Asm, Next: Constraints, Prev: Inline, Up: C Extensions
-
-Assembler Instructions with C Expression Operands
-=================================================
-
- In an assembler instruction using `asm', you can specify the
-operands of the instruction using C expressions. This means you need
-not guess which registers or memory locations will contain the data you
-want to use.
-
- You must specify an assembler instruction template much like what
-appears in a machine description, plus an operand constraint string for
-each operand.
-
- For example, here is how to use the 68881's `fsinx' instruction:
-
- asm ("fsinx %1,%0" : "=f" (result) : "f" (angle));
-
-Here `angle' is the C expression for the input operand while `result'
-is that of the output operand. Each has `"f"' as its operand
-constraint, saying that a floating point register is required. The `='
-in `=f' indicates that the operand is an output; all output operands'
-constraints must use `='. The constraints use the same language used
-in the machine description (*note Constraints::).
-
- Each operand is described by an operand-constraint string followed by
-the C expression in parentheses. A colon separates the assembler
-template from the first output operand and another separates the last
-output operand from the first input, if any. Commas separate the
-operands within each group. The total number of operands is currently
-limited to 30; this limitation may be lifted in some future version of
-GCC.
-
- If there are no output operands but there are input operands, you
-must place two consecutive colons surrounding the place where the output
-operands would go.
-
- As of GCC version 3.1, it is also possible to specify input and
-output operands using symbolic names which can be referenced within the
-assembler code. These names are specified inside square brackets
-preceding the constraint string, and can be referenced inside the
-assembler code using `%[NAME]' instead of a percentage sign followed by
-the operand number. Using named operands the above example could look
-like:
-
- asm ("fsinx %[angle],%[output]"
- : [output] "=f" (result)
- : [angle] "f" (angle));
-
-Note that the symbolic operand names have no relation whatsoever to
-other C identifiers. You may use any name you like, even those of
-existing C symbols, but must ensure that no two operands within the same
-assembler construct use the same symbolic name.
-
- Output operand expressions must be lvalues; the compiler can check
-this. The input operands need not be lvalues. The compiler cannot
-check whether the operands have data types that are reasonable for the
-instruction being executed. It does not parse the assembler instruction
-template and does not know what it means or even whether it is valid
-assembler input. The extended `asm' feature is most often used for
-machine instructions the compiler itself does not know exist. If the
-output expression cannot be directly addressed (for example, it is a
-bit-field), your constraint must allow a register. In that case, GCC
-will use the register as the output of the `asm', and then store that
-register into the output.
-
- The ordinary output operands must be write-only; GCC will assume that
-the values in these operands before the instruction are dead and need
-not be generated. Extended asm supports input-output or read-write
-operands. Use the constraint character `+' to indicate such an operand
-and list it with the output operands.
-
- When the constraints for the read-write operand (or the operand in
-which only some of the bits are to be changed) allows a register, you
-may, as an alternative, logically split its function into two separate
-operands, one input operand and one write-only output operand. The
-connection between them is expressed by constraints which say they need
-to be in the same location when the instruction executes. You can use
-the same C expression for both operands, or different expressions. For
-example, here we write the (fictitious) `combine' instruction with
-`bar' as its read-only source operand and `foo' as its read-write
-destination:
-
- asm ("combine %2,%0" : "=r" (foo) : "0" (foo), "g" (bar));
-
-The constraint `"0"' for operand 1 says that it must occupy the same
-location as operand 0. A number in constraint is allowed only in an
-input operand and it must refer to an output operand.
-
- Only a number in the constraint can guarantee that one operand will
-be in the same place as another. The mere fact that `foo' is the value
-of both operands is not enough to guarantee that they will be in the
-same place in the generated assembler code. The following would not
-work reliably:
-
- asm ("combine %2,%0" : "=r" (foo) : "r" (foo), "g" (bar));
-
- Various optimizations or reloading could cause operands 0 and 1 to
-be in different registers; GCC knows no reason not to do so. For
-example, the compiler might find a copy of the value of `foo' in one
-register and use it for operand 1, but generate the output operand 0 in
-a different register (copying it afterward to `foo''s own address). Of
-course, since the register for operand 1 is not even mentioned in the
-assembler code, the result will not work, but GCC can't tell that.
-
- As of GCC version 3.1, one may write `[NAME]' instead of the operand
-number for a matching constraint. For example:
-
- asm ("cmoveq %1,%2,%[result]"
- : [result] "=r"(result)
- : "r" (test), "r"(new), "[result]"(old));
-
- Some instructions clobber specific hard registers. To describe this,
-write a third colon after the input operands, followed by the names of
-the clobbered hard registers (given as strings). Here is a realistic
-example for the VAX:
-
- asm volatile ("movc3 %0,%1,%2"
- : /* no outputs */
- : "g" (from), "g" (to), "g" (count)
- : "r0", "r1", "r2", "r3", "r4", "r5");
-
- You may not write a clobber description in a way that overlaps with
-an input or output operand. For example, you may not have an operand
-describing a register class with one member if you mention that register
-in the clobber list. There is no way for you to specify that an input
-operand is modified without also specifying it as an output operand.
-Note that if all the output operands you specify are for this purpose
-(and hence unused), you will then also need to specify `volatile' for
-the `asm' construct, as described below, to prevent GCC from deleting
-the `asm' statement as unused.
-
- If you refer to a particular hardware register from the assembler
-code, you will probably have to list the register after the third colon
-to tell the compiler the register's value is modified. In some
-assemblers, the register names begin with `%'; to produce one `%' in the
-assembler code, you must write `%%' in the input.
-
- If your assembler instruction can alter the condition code register,
-add `cc' to the list of clobbered registers. GCC on some machines
-represents the condition codes as a specific hardware register; `cc'
-serves to name this register. On other machines, the condition code is
-handled differently, and specifying `cc' has no effect. But it is
-valid no matter what the machine.
-
- If your assembler instruction modifies memory in an unpredictable
-fashion, add `memory' to the list of clobbered registers. This will
-cause GCC to not keep memory values cached in registers across the
-assembler instruction. You will also want to add the `volatile'
-keyword if the memory affected is not listed in the inputs or outputs
-of the `asm', as the `memory' clobber does not count as a side-effect
-of the `asm'.
-
- You can put multiple assembler instructions together in a single
-`asm' template, separated by the characters normally used in assembly
-code for the system. A combination that works in most places is a
-newline to break the line, plus a tab character to move to the
-instruction field (written as `\n\t'). Sometimes semicolons can be
-used, if the assembler allows semicolons as a line-breaking character.
-Note that some assembler dialects use semicolons to start a comment.
-The input operands are guaranteed not to use any of the clobbered
-registers, and neither will the output operands' addresses, so you can
-read and write the clobbered registers as many times as you like. Here
-is an example of multiple instructions in a template; it assumes the
-subroutine `_foo' accepts arguments in registers 9 and 10:
-
- asm ("movl %0,r9\n\tmovl %1,r10\n\tcall _foo"
- : /* no outputs */
- : "g" (from), "g" (to)
- : "r9", "r10");
-
- Unless an output operand has the `&' constraint modifier, GCC may
-allocate it in the same register as an unrelated input operand, on the
-assumption the inputs are consumed before the outputs are produced.
-This assumption may be false if the assembler code actually consists of
-more than one instruction. In such a case, use `&' for each output
-operand that may not overlap an input. *Note Modifiers::.
-
- If you want to test the condition code produced by an assembler
-instruction, you must include a branch and a label in the `asm'
-construct, as follows:
-
- asm ("clr %0\n\tfrob %1\n\tbeq 0f\n\tmov #1,%0\n0:"
- : "g" (result)
- : "g" (input));
-
-This assumes your assembler supports local labels, as the GNU assembler
-and most Unix assemblers do.
-
- Speaking of labels, jumps from one `asm' to another are not
-supported. The compiler's optimizers do not know about these jumps, and
-therefore they cannot take account of them when deciding how to
-optimize.
-
- Usually the most convenient way to use these `asm' instructions is to
-encapsulate them in macros that look like functions. For example,
-
- #define sin(x) \
- ({ double __value, __arg = (x); \
- asm ("fsinx %1,%0": "=f" (__value): "f" (__arg)); \
- __value; })
-
-Here the variable `__arg' is used to make sure that the instruction
-operates on a proper `double' value, and to accept only those arguments
-`x' which can convert automatically to a `double'.
-
- Another way to make sure the instruction operates on the correct data
-type is to use a cast in the `asm'. This is different from using a
-variable `__arg' in that it converts more different types. For
-example, if the desired type were `int', casting the argument to `int'
-would accept a pointer with no complaint, while assigning the argument
-to an `int' variable named `__arg' would warn about using a pointer
-unless the caller explicitly casts it.
-
- If an `asm' has output operands, GCC assumes for optimization
-purposes the instruction has no side effects except to change the output
-operands. This does not mean instructions with a side effect cannot be
-used, but you must be careful, because the compiler may eliminate them
-if the output operands aren't used, or move them out of loops, or
-replace two with one if they constitute a common subexpression. Also,
-if your instruction does have a side effect on a variable that otherwise
-appears not to change, the old value of the variable may be reused later
-if it happens to be found in a register.
-
- You can prevent an `asm' instruction from being deleted, moved
-significantly, or combined, by writing the keyword `volatile' after the
-`asm'. For example:
-
- #define get_and_set_priority(new) \
- ({ int __old; \
- asm volatile ("get_and_set_priority %0, %1" \
- : "=g" (__old) : "g" (new)); \
- __old; })
-
-If you write an `asm' instruction with no outputs, GCC will know the
-instruction has side-effects and will not delete the instruction or
-move it outside of loops.
-
- The `volatile' keyword indicates that the instruction has important
-side-effects. GCC will not delete a volatile `asm' if it is reachable.
-(The instruction can still be deleted if GCC can prove that
-control-flow will never reach the location of the instruction.) In
-addition, GCC will not reschedule instructions across a volatile `asm'
-instruction. For example:
-
- *(volatile int *)addr = foo;
- asm volatile ("eieio" : : );
-
-Assume `addr' contains the address of a memory mapped device register.
-The PowerPC `eieio' instruction (Enforce In-order Execution of I/O)
-tells the CPU to make sure that the store to that device register
-happens before it issues any other I/O.
-
- Note that even a volatile `asm' instruction can be moved in ways
-that appear insignificant to the compiler, such as across jump
-instructions. You can't expect a sequence of volatile `asm'
-instructions to remain perfectly consecutive. If you want consecutive
-output, use a single `asm'. Also, GCC will perform some optimizations
-across a volatile `asm' instruction; GCC does not "forget everything"
-when it encounters a volatile `asm' instruction the way some other
-compilers do.
-
- An `asm' instruction without any operands or clobbers (an "old
-style" `asm') will be treated identically to a volatile `asm'
-instruction.
-
- It is a natural idea to look for a way to give access to the
-condition code left by the assembler instruction. However, when we
-attempted to implement this, we found no way to make it work reliably.
-The problem is that output operands might need reloading, which would
-result in additional following "store" instructions. On most machines,
-these instructions would alter the condition code before there was time
-to test it. This problem doesn't arise for ordinary "test" and
-"compare" instructions because they don't have any output operands.
-
- For reasons similar to those described above, it is not possible to
-give an assembler instruction access to the condition code left by
-previous instructions.
-
- If you are writing a header file that should be includable in ISO C
-programs, write `__asm__' instead of `asm'. *Note Alternate Keywords::.
-
-i386 floating point asm operands
---------------------------------
-
- There are several rules on the usage of stack-like regs in
-asm_operands insns. These rules apply only to the operands that are
-stack-like regs:
-
- 1. Given a set of input regs that die in an asm_operands, it is
- necessary to know which are implicitly popped by the asm, and
- which must be explicitly popped by gcc.
-
- An input reg that is implicitly popped by the asm must be
- explicitly clobbered, unless it is constrained to match an output
- operand.
-
- 2. For any input reg that is implicitly popped by an asm, it is
- necessary to know how to adjust the stack to compensate for the
- pop. If any non-popped input is closer to the top of the
- reg-stack than the implicitly popped reg, it would not be possible
- to know what the stack looked like--it's not clear how the rest of
- the stack "slides up".
-
- All implicitly popped input regs must be closer to the top of the
- reg-stack than any input that is not implicitly popped.
-
- It is possible that if an input dies in an insn, reload might use
- the input reg for an output reload. Consider this example:
-
- asm ("foo" : "=t" (a) : "f" (b));
-
- This asm says that input B is not popped by the asm, and that the
- asm pushes a result onto the reg-stack, i.e., the stack is one
- deeper after the asm than it was before. But, it is possible that
- reload will think that it can use the same reg for both the input
- and the output, if input B dies in this insn.
-
- If any input operand uses the `f' constraint, all output reg
- constraints must use the `&' earlyclobber.
-
- The asm above would be written as
-
- asm ("foo" : "=&t" (a) : "f" (b));
-
- 3. Some operands need to be in particular places on the stack. All
- output operands fall in this category--there is no other way to
- know which regs the outputs appear in unless the user indicates
- this in the constraints.
-
- Output operands must specifically indicate which reg an output
- appears in after an asm. `=f' is not allowed: the operand
- constraints must select a class with a single reg.
-
- 4. Output operands may not be "inserted" between existing stack regs.
- Since no 387 opcode uses a read/write operand, all output operands
- are dead before the asm_operands, and are pushed by the
- asm_operands. It makes no sense to push anywhere but the top of
- the reg-stack.
-
- Output operands must start at the top of the reg-stack: output
- operands may not "skip" a reg.
-
- 5. Some asm statements may need extra stack space for internal
- calculations. This can be guaranteed by clobbering stack registers
- unrelated to the inputs and outputs.
-
-
- Here are a couple of reasonable asms to want to write. This asm
-takes one input, which is internally popped, and produces two outputs.
-
- asm ("fsincos" : "=t" (cos), "=u" (sin) : "0" (inp));
-
- This asm takes two inputs, which are popped by the `fyl2xp1' opcode,
-and replaces them with one output. The user must code the `st(1)'
-clobber for reg-stack.c to know that `fyl2xp1' pops both inputs.
-
- asm ("fyl2xp1" : "=t" (result) : "0" (x), "u" (y) : "st(1)");
-
-\1f
-File: gcc.info, Node: Constraints, Next: Asm Labels, Prev: Extended Asm, Up: C Extensions
-
-Constraints for `asm' Operands
-==============================
-
- Here are specific details on what constraint letters you can use with
-`asm' operands. Constraints can say whether an operand may be in a
-register, and which kinds of register; whether the operand can be a
-memory reference, and which kinds of address; whether the operand may
-be an immediate constant, and which possible values it may have.
-Constraints can also require two operands to match.
-
-* Menu:
-
-* Simple Constraints:: Basic use of constraints.
-* Multi-Alternative:: When an insn has two alternative constraint-patterns.
-* Modifiers:: More precise control over effects of constraints.
-* Machine Constraints:: Special constraints for some particular machines.
-
-\1f
-File: gcc.info, Node: Simple Constraints, Next: Multi-Alternative, Up: Constraints
-
-Simple Constraints
-------------------
-
- The simplest kind of constraint is a string full of letters, each of
-which describes one kind of operand that is permitted. Here are the
-letters that are allowed:
-
-whitespace
- Whitespace characters are ignored and can be inserted at any
- position except the first. This enables each alternative for
- different operands to be visually aligned in the machine
- description even if they have different number of constraints and
- modifiers.
-
-`m'
- A memory operand is allowed, with any kind of address that the
- machine supports in general.
-
-`o'
- A memory operand is allowed, but only if the address is
- "offsettable". This means that adding a small integer (actually,
- the width in bytes of the operand, as determined by its machine
- mode) may be added to the address and the result is also a valid
- memory address.
-
- For example, an address which is constant is offsettable; so is an
- address that is the sum of a register and a constant (as long as a
- slightly larger constant is also within the range of
- address-offsets supported by the machine); but an autoincrement or
- autodecrement address is not offsettable. More complicated
- indirect/indexed addresses may or may not be offsettable depending
- on the other addressing modes that the machine supports.
-
- Note that in an output operand which can be matched by another
- operand, the constraint letter `o' is valid only when accompanied
- by both `<' (if the target machine has predecrement addressing)
- and `>' (if the target machine has preincrement addressing).
-
-`V'
- A memory operand that is not offsettable. In other words,
- anything that would fit the `m' constraint but not the `o'
- constraint.
-
-`<'
- A memory operand with autodecrement addressing (either
- predecrement or postdecrement) is allowed.
-
-`>'
- A memory operand with autoincrement addressing (either
- preincrement or postincrement) is allowed.
-
-`r'
- A register operand is allowed provided that it is in a general
- register.
-
-`i'
- An immediate integer operand (one with constant value) is allowed.
- This includes symbolic constants whose values will be known only at
- assembly time.
-
-`n'
- An immediate integer operand with a known numeric value is allowed.
- Many systems cannot support assembly-time constants for operands
- less than a word wide. Constraints for these operands should use
- `n' rather than `i'.
-
-`I', `J', `K', ... `P'
- Other letters in the range `I' through `P' may be defined in a
- machine-dependent fashion to permit immediate integer operands with
- explicit integer values in specified ranges. For example, on the
- 68000, `I' is defined to stand for the range of values 1 to 8.
- This is the range permitted as a shift count in the shift
- instructions.
-
-`E'
- An immediate floating operand (expression code `const_double') is
- allowed, but only if the target floating point format is the same
- as that of the host machine (on which the compiler is running).
-
-`F'
- An immediate floating operand (expression code `const_double') is
- allowed.
-
-`G', `H'
- `G' and `H' may be defined in a machine-dependent fashion to
- permit immediate floating operands in particular ranges of values.
-
-`s'
- An immediate integer operand whose value is not an explicit
- integer is allowed.
-
- This might appear strange; if an insn allows a constant operand
- with a value not known at compile time, it certainly must allow
- any known value. So why use `s' instead of `i'? Sometimes it
- allows better code to be generated.
-
- For example, on the 68000 in a fullword instruction it is possible
- to use an immediate operand; but if the immediate value is between
- -128 and 127, better code results from loading the value into a
- register and using the register. This is because the load into
- the register can be done with a `moveq' instruction. We arrange
- for this to happen by defining the letter `K' to mean "any integer
- outside the range -128 to 127", and then specifying `Ks' in the
- operand constraints.
-
-`g'
- Any register, memory or immediate integer operand is allowed,
- except for registers that are not general registers.
-
-`X'
- Any operand whatsoever is allowed.
-
-`0', `1', `2', ... `9'
- An operand that matches the specified operand number is allowed.
- If a digit is used together with letters within the same
- alternative, the digit should come last.
-
- This number is allowed to be more than a single digit. If multiple
- digits are encountered consecutavely, they are interpreted as a
- single decimal integer. There is scant chance for ambiguity,
- since to-date it has never been desirable that `10' be interpreted
- as matching either operand 1 _or_ operand 0. Should this be
- desired, one can use multiple alternatives instead.
-
- This is called a "matching constraint" and what it really means is
- that the assembler has only a single operand that fills two roles
- which `asm' distinguishes. For example, an add instruction uses
- two input operands and an output operand, but on most CISC
- machines an add instruction really has only two operands, one of
- them an input-output operand:
-
- addl #35,r12
-
- Matching constraints are used in these circumstances. More
- precisely, the two operands that match must include one input-only
- operand and one output-only operand. Moreover, the digit must be a
- smaller number than the number of the operand that uses it in the
- constraint.
-
-`p'
- An operand that is a valid memory address is allowed. This is for
- "load address" and "push address" instructions.
-
- `p' in the constraint must be accompanied by `address_operand' as
- the predicate in the `match_operand'. This predicate interprets
- the mode specified in the `match_operand' as the mode of the memory
- reference for which the address would be valid.
-
-OTHER-LETTERS
- Other letters can be defined in machine-dependent fashion to stand
- for particular classes of registers or other arbitrary operand
- types. `d', `a' and `f' are defined on the 68000/68020 to stand
- for data, address and floating point registers.
-
-
-\1f
-File: gcc.info, Node: Multi-Alternative, Next: Modifiers, Prev: Simple Constraints, Up: Constraints
-
-Multiple Alternative Constraints
---------------------------------
-
- Sometimes a single instruction has multiple alternative sets of
-possible operands. For example, on the 68000, a logical-or instruction
-can combine register or an immediate value into memory, or it can
-combine any kind of operand into a register; but it cannot combine one
-memory location into another.
-
- These constraints are represented as multiple alternatives. An
-alternative can be described by a series of letters for each operand.
-The overall constraint for an operand is made from the letters for this
-operand from the first alternative, a comma, the letters for this
-operand from the second alternative, a comma, and so on until the last
-alternative.
-
- If all the operands fit any one alternative, the instruction is
-valid. Otherwise, for each alternative, the compiler counts how many
-instructions must be added to copy the operands so that that
-alternative applies. The alternative requiring the least copying is
-chosen. If two alternatives need the same amount of copying, the one
-that comes first is chosen. These choices can be altered with the `?'
-and `!' characters:
-
-`?'
- Disparage slightly the alternative that the `?' appears in, as a
- choice when no alternative applies exactly. The compiler regards
- this alternative as one unit more costly for each `?' that appears
- in it.
-
-`!'
- Disparage severely the alternative that the `!' appears in. This
- alternative can still be used if it fits without reloading, but if
- reloading is needed, some other alternative will be used.
-
-\1f
-File: gcc.info, Node: Modifiers, Next: Machine Constraints, Prev: Multi-Alternative, Up: Constraints
-
-Constraint Modifier Characters
-------------------------------
-
- Here are constraint modifier characters.
-
-`='
- Means that this operand is write-only for this instruction: the
- previous value is discarded and replaced by output data.
-
-`+'
- Means that this operand is both read and written by the
- instruction.
-
- When the compiler fixes up the operands to satisfy the constraints,
- it needs to know which operands are inputs to the instruction and
- which are outputs from it. `=' identifies an output; `+'
- identifies an operand that is both input and output; all other
- operands are assumed to be input only.
-
- If you specify `=' or `+' in a constraint, you put it in the first
- character of the constraint string.
-
-`&'
- Means (in a particular alternative) that this operand is an
- "earlyclobber" operand, which is modified before the instruction is
- finished using the input operands. Therefore, this operand may
- not lie in a register that is used as an input operand or as part
- of any memory address.
-
- `&' applies only to the alternative in which it is written. In
- constraints with multiple alternatives, sometimes one alternative
- requires `&' while others do not. See, for example, the `movdf'
- insn of the 68000.
-
- An input operand can be tied to an earlyclobber operand if its only
- use as an input occurs before the early result is written. Adding
- alternatives of this form often allows GCC to produce better code
- when only some of the inputs can be affected by the earlyclobber.
- See, for example, the `mulsi3' insn of the ARM.
-
- `&' does not obviate the need to write `='.
-
-`%'
- Declares the instruction to be commutative for this operand and the
- following operand. This means that the compiler may interchange
- the two operands if that is the cheapest way to make all operands
- fit the constraints.
-
-`#'
- Says that all following characters, up to the next comma, are to be
- ignored as a constraint. They are significant only for choosing
- register preferences.
-
-`*'
- Says that the following character should be ignored when choosing
- register preferences. `*' has no effect on the meaning of the
- constraint as a constraint, and no effect on reloading.
-
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Machine Constraints, Prev: Modifiers, Up: Constraints
-
-Constraints for Particular Machines
------------------------------------
-
- Whenever possible, you should use the general-purpose constraint
-letters in `asm' arguments, since they will convey meaning more readily
-to people reading your code. Failing that, use the constraint letters
-that usually have very similar meanings across architectures. The most
-commonly used constraints are `m' and `r' (for memory and
-general-purpose registers respectively; *note Simple Constraints::), and
-`I', usually the letter indicating the most common immediate-constant
-format.
-
- For each machine architecture, the `config/MACHINE/MACHINE.h' file
-defines additional constraints. These constraints are used by the
-compiler itself for instruction generation, as well as for `asm'
-statements; therefore, some of the constraints are not particularly
-interesting for `asm'. The constraints are defined through these
-macros:
-
-`REG_CLASS_FROM_LETTER'
- Register class constraints (usually lower case).
-
-`CONST_OK_FOR_LETTER_P'
- Immediate constant constraints, for non-floating point constants of
- word size or smaller precision (usually upper case).
-
-`CONST_DOUBLE_OK_FOR_LETTER_P'
- Immediate constant constraints, for all floating point constants
- and for constants of greater than word size precision (usually
- upper case).
-
-`EXTRA_CONSTRAINT'
- Special cases of registers or memory. This macro is not required,
- and is only defined for some machines.
-
- Inspecting these macro definitions in the compiler source for your
-machine is the best way to be certain you have the right constraints.
-However, here is a summary of the machine-dependent constraints
-available on some particular machines.
-
-_ARM family--`arm.h'_
-
- `f'
- Floating-point register
-
- `F'
- One of the floating-point constants 0.0, 0.5, 1.0, 2.0, 3.0,
- 4.0, 5.0 or 10.0
-
- `G'
- Floating-point constant that would satisfy the constraint `F'
- if it were negated
-
- `I'
- Integer that is valid as an immediate operand in a data
- processing instruction. That is, an integer in the range 0
- to 255 rotated by a multiple of 2
-
- `J'
- Integer in the range -4095 to 4095
-
- `K'
- Integer that satisfies constraint `I' when inverted (ones
- complement)
-
- `L'
- Integer that satisfies constraint `I' when negated (twos
- complement)
-
- `M'
- Integer in the range 0 to 32
-
- `Q'
- A memory reference where the exact address is in a single
- register (``m'' is preferable for `asm' statements)
-
- `R'
- An item in the constant pool
-
- `S'
- A symbol in the text segment of the current file
-
-_AMD 29000 family--`a29k.h'_
-
- `l'
- Local register 0
-
- `b'
- Byte Pointer (`BP') register
-
- `q'
- `Q' register
-
- `h'
- Special purpose register
-
- `A'
- First accumulator register
-
- `a'
- Other accumulator register
-
- `f'
- Floating point register
-
- `I'
- Constant greater than 0, less than 0x100
-
- `J'
- Constant greater than 0, less than 0x10000
-
- `K'
- Constant whose high 24 bits are on (1)
-
- `L'
- 16-bit constant whose high 8 bits are on (1)
-
- `M'
- 32-bit constant whose high 16 bits are on (1)
-
- `N'
- 32-bit negative constant that fits in 8 bits
-
- `O'
- The constant 0x80000000 or, on the 29050, any 32-bit constant
- whose low 16 bits are 0.
-
- `P'
- 16-bit negative constant that fits in 8 bits
-
- `G'
- `H'
- A floating point constant (in `asm' statements, use the
- machine independent `E' or `F' instead)
-
-_AVR family--`avr.h'_
-
- `l'
- Registers from r0 to r15
-
- `a'
- Registers from r16 to r23
-
- `d'
- Registers from r16 to r31
-
- `w'
- Registers from r24 to r31. These registers can be used in
- `adiw' command
-
- `e'
- Pointer register (r26-r31)
-
- `b'
- Base pointer register (r28-r31)
-
- `q'
- Stack pointer register (SPH:SPL)
-
- `t'
- Temporary register r0
-
- `x'
- Register pair X (r27:r26)
-
- `y'
- Register pair Y (r29:r28)
-
- `z'
- Register pair Z (r31:r30)
-
- `I'
- Constant greater than -1, less than 64
-
- `J'
- Constant greater than -64, less than 1
-
- `K'
- Constant integer 2
-
- `L'
- Constant integer 0
-
- `M'
- Constant that fits in 8 bits
-
- `N'
- Constant integer -1
-
- `O'
- Constant integer 8, 16, or 24
-
- `P'
- Constant integer 1
-
- `G'
- A floating point constant 0.0
-
-_IBM RS6000--`rs6000.h'_
-
- `b'
- Address base register
-
- `f'
- Floating point register
-
- `h'
- `MQ', `CTR', or `LINK' register
-
- `q'
- `MQ' register
-
- `c'
- `CTR' register
-
- `l'
- `LINK' register
-
- `x'
- `CR' register (condition register) number 0
-
- `y'
- `CR' register (condition register)
-
- `z'
- `FPMEM' stack memory for FPR-GPR transfers
-
- `I'
- Signed 16-bit constant
-
- `J'
- Unsigned 16-bit constant shifted left 16 bits (use `L'
- instead for `SImode' constants)
-
- `K'
- Unsigned 16-bit constant
-
- `L'
- Signed 16-bit constant shifted left 16 bits
-
- `M'
- Constant larger than 31
-
- `N'
- Exact power of 2
-
- `O'
- Zero
-
- `P'
- Constant whose negation is a signed 16-bit constant
-
- `G'
- Floating point constant that can be loaded into a register
- with one instruction per word
-
- `Q'
- Memory operand that is an offset from a register (`m' is
- preferable for `asm' statements)
-
- `R'
- AIX TOC entry
-
- `S'
- Constant suitable as a 64-bit mask operand
-
- `T'
- Constant suitable as a 32-bit mask operand
-
- `U'
- System V Release 4 small data area reference
-
-_Intel 386--`i386.h'_
-
- `q'
- `a', `b', `c', or `d' register for the i386. For x86-64 it
- is equivalent to `r' class. (for 8-bit instructions that do
- not use upper halves)
-
- `Q'
- `a', `b', `c', or `d' register. (for 8-bit instructions, that
- do use upper halves)
-
- `R'
- Legacy register--equivalent to `r' class in i386 mode. (for
- non-8-bit registers used together with 8-bit upper halves in
- a single instruction)
-
- `A'
- Specifies the `a' or `d' registers. This is primarily useful
- for 64-bit integer values (when in 32-bit mode) intended to
- be returned with the `d' register holding the most
- significant bits and the `a' register holding the least
- significant bits.
-
- `f'
- Floating point register
-
- `t'
- First (top of stack) floating point register
-
- `u'
- Second floating point register
-
- `a'
- `a' register
-
- `b'
- `b' register
-
- `c'
- `c' register
-
- `d'
- `d' register
-
- `D'
- `di' register
-
- `S'
- `si' register
-
- `x'
- `xmm' SSE register
-
- `y'
- MMX register
-
- `I'
- Constant in range 0 to 31 (for 32-bit shifts)
-
- `J'
- Constant in range 0 to 63 (for 64-bit shifts)
-
- `K'
- `0xff'
-
- `L'
- `0xffff'
-
- `M'
- 0, 1, 2, or 3 (shifts for `lea' instruction)
-
- `N'
- Constant in range 0 to 255 (for `out' instruction)
-
- `Z'
- Constant in range 0 to `0xffffffff' or symbolic reference
- known to fit specified range. (for using immediates in zero
- extending 32-bit to 64-bit x86-64 instructions)
-
- `e'
- Constant in range -2147483648 to 2147483647 or symbolic
- reference known to fit specified range. (for using
- immediates in 64-bit x86-64 instructions)
-
- `G'
- Standard 80387 floating point constant
-
-_Intel 960--`i960.h'_
-
- `f'
- Floating point register (`fp0' to `fp3')
-
- `l'
- Local register (`r0' to `r15')
-
- `b'
- Global register (`g0' to `g15')
-
- `d'
- Any local or global register
-
- `I'
- Integers from 0 to 31
-
- `J'
- 0
-
- `K'
- Integers from -31 to 0
-
- `G'
- Floating point 0
-
- `H'
- Floating point 1
-
-_MIPS--`mips.h'_
-
- `d'
- General-purpose integer register
-
- `f'
- Floating-point register (if available)
-
- `h'
- `Hi' register
-
- `l'
- `Lo' register
-
- `x'
- `Hi' or `Lo' register
-
- `y'
- General-purpose integer register
-
- `z'
- Floating-point status register
-
- `I'
- Signed 16-bit constant (for arithmetic instructions)
-
- `J'
- Zero
-
- `K'
- Zero-extended 16-bit constant (for logic instructions)
-
- `L'
- Constant with low 16 bits zero (can be loaded with `lui')
-
- `M'
- 32-bit constant which requires two instructions to load (a
- constant which is not `I', `K', or `L')
-
- `N'
- Negative 16-bit constant
-
- `O'
- Exact power of two
-
- `P'
- Positive 16-bit constant
-
- `G'
- Floating point zero
-
- `Q'
- Memory reference that can be loaded with more than one
- instruction (`m' is preferable for `asm' statements)
-
- `R'
- Memory reference that can be loaded with one instruction (`m'
- is preferable for `asm' statements)
-
- `S'
- Memory reference in external OSF/rose PIC format (`m' is
- preferable for `asm' statements)
-
-_Motorola 680x0--`m68k.h'_
-
- `a'
- Address register
-
- `d'
- Data register
-
- `f'
- 68881 floating-point register, if available
-
- `x'
- Sun FPA (floating-point) register, if available
-
- `y'
- First 16 Sun FPA registers, if available
-
- `I'
- Integer in the range 1 to 8
-
- `J'
- 16-bit signed number
-
- `K'
- Signed number whose magnitude is greater than 0x80
-
- `L'
- Integer in the range -8 to -1
-
- `M'
- Signed number whose magnitude is greater than 0x100
-
- `G'
- Floating point constant that is not a 68881 constant
-
- `H'
- Floating point constant that can be used by Sun FPA
-
-_Motorola 68HC11 & 68HC12 families--`m68hc11.h'_
-
- `a'
- Register 'a'
-
- `b'
- Register 'b'
-
- `d'
- Register 'd'
-
- `q'
- An 8-bit register
-
- `t'
- Temporary soft register _.tmp
-
- `u'
- A soft register _.d1 to _.d31
-
- `w'
- Stack pointer register
-
- `x'
- Register 'x'
-
- `y'
- Register 'y'
-
- `z'
- Pseudo register 'z' (replaced by 'x' or 'y' at the end)
-
- `A'
- An address register: x, y or z
-
- `B'
- An address register: x or y
-
- `D'
- Register pair (x:d) to form a 32-bit value
-
- `L'
- Constants in the range -65536 to 65535
-
- `M'
- Constants whose 16-bit low part is zero
-
- `N'
- Constant integer 1 or -1
-
- `O'
- Constant integer 16
-
- `P'
- Constants in the range -8 to 2
-
-
-_SPARC--`sparc.h'_
-
- `f'
- Floating-point register that can hold 32- or 64-bit values.
-
- `e'
- Floating-point register that can hold 64- or 128-bit values.
-
- `I'
- Signed 13-bit constant
-
- `J'
- Zero
-
- `K'
- 32-bit constant with the low 12 bits clear (a constant that
- can be loaded with the `sethi' instruction)
-
- `L'
- A constant in the range supported by `movcc' instructions
-
- `M'
- A constant in the range supported by `movrcc' instructions
-
- `N'
- Same as `K', except that it verifies that bits that are not
- in the lower 32-bit range are all zero. Must be used instead
- of `K' for modes wider than `SImode'
-
- `G'
- Floating-point zero
-
- `H'
- Signed 13-bit constant, sign-extended to 32 or 64 bits
-
- `Q'
- Floating-point constant whose integral representation can be
- moved into an integer register using a single sethi
- instruction
-
- `R'
- Floating-point constant whose integral representation can be
- moved into an integer register using a single mov instruction
-
- `S'
- Floating-point constant whose integral representation can be
- moved into an integer register using a high/lo_sum
- instruction sequence
-
- `T'
- Memory address aligned to an 8-byte boundary
-
- `U'
- Even register
-
- `W'
- Memory address for `e' constraint registers.
-
-
-_TMS320C3x/C4x--`c4x.h'_
-
- `a'
- Auxiliary (address) register (ar0-ar7)
-
- `b'
- Stack pointer register (sp)
-
- `c'
- Standard (32-bit) precision integer register
-
- `f'
- Extended (40-bit) precision register (r0-r11)
-
- `k'
- Block count register (bk)
-
- `q'
- Extended (40-bit) precision low register (r0-r7)
-
- `t'
- Extended (40-bit) precision register (r0-r1)
-
- `u'
- Extended (40-bit) precision register (r2-r3)
-
- `v'
- Repeat count register (rc)
-
- `x'
- Index register (ir0-ir1)
-
- `y'
- Status (condition code) register (st)
-
- `z'
- Data page register (dp)
-
- `G'
- Floating-point zero
-
- `H'
- Immediate 16-bit floating-point constant
-
- `I'
- Signed 16-bit constant
-
- `J'
- Signed 8-bit constant
-
- `K'
- Signed 5-bit constant
-
- `L'
- Unsigned 16-bit constant
-
- `M'
- Unsigned 8-bit constant
-
- `N'
- Ones complement of unsigned 16-bit constant
-
- `O'
- High 16-bit constant (32-bit constant with 16 LSBs zero)
-
- `Q'
- Indirect memory reference with signed 8-bit or index register
- displacement
-
- `R'
- Indirect memory reference with unsigned 5-bit displacement
-
- `S'
- Indirect memory reference with 1 bit or index register
- displacement
-
- `T'
- Direct memory reference
-
- `U'
- Symbolic address
-
-
-_S/390 and zSeries--`s390.h'_
-
- `a'
- Address register (general purpose register except r0)
-
- `d'
- Data register (arbitrary general purpose register)
-
- `f'
- Floating-point register
-
- `I'
- Unsigned 8-bit constant (0-255)
-
- `J'
- Unsigned 12-bit constant (0-4095)
-
- `K'
- Signed 16-bit constant (-32768-32767)
-
- `L'
- Unsigned 16-bit constant (0-65535)
-
- `Q'
- Memory reference without index register
-
- `S'
- Symbolic constant suitable for use with the `larl' instruction
-
-
-_Xstormy16--`stormy16.h'_
-
- `a'
- Register r0.
-
- `b'
- Register r1.
-
- `c'
- Register r2.
-
- `d'
- Register r8.
-
- `e'
- Registers r0 through r7.
-
- `t'
- Registers r0 and r1.
-
- `y'
- The carry register.
-
- `z'
- Registers r8 and r9.
-
- `I'
- A constant between 0 and 3 inclusive.
-
- `J'
- A constant that has exactly one bit set.
-
- `K'
- A constant that has exactly one bit clear.
-
- `L'
- A constant between 0 and 255 inclusive.
-
- `M'
- A constant between -255 and 0 inclusive.
-
- `N'
- A constant between -3 and 0 inclusive.
-
- `O'
- A constant between 1 and 4 inclusive.
-
- `P'
- A constant between -4 and -1 inclusive.
-
- `Q'
- A memory reference that is a stack push.
-
- `R'
- A memory reference that is a stack pop.
-
- `S'
- A memory reference that refers to an constant address of
- known value.
-
- `T'
- The register indicated by Rx (not implemented yet).
-
- `U'
- A constant that is not between 2 and 15 inclusive.
-
-
-_Xtensa--`xtensa.h'_
-
- `a'
- General-purpose 32-bit register
-
- `b'
- One-bit boolean register
-
- `A'
- MAC16 40-bit accumulator register
-
- `I'
- Signed 12-bit integer constant, for use in MOVI instructions
-
- `J'
- Signed 8-bit integer constant, for use in ADDI instructions
-
- `K'
- Integer constant valid for BccI instructions
-
- `L'
- Unsigned constant valid for BccUI instructions
-
-
-
-\1f
-File: gcc.info, Node: Asm Labels, Next: Explicit Reg Vars, Prev: Constraints, Up: C Extensions
-
-Controlling Names Used in Assembler Code
-========================================
-
- You can specify the name to be used in the assembler code for a C
-function or variable by writing the `asm' (or `__asm__') keyword after
-the declarator as follows:
-
- int foo asm ("myfoo") = 2;
-
-This specifies that the name to be used for the variable `foo' in the
-assembler code should be `myfoo' rather than the usual `_foo'.
-
- On systems where an underscore is normally prepended to the name of
-a C function or variable, this feature allows you to define names for
-the linker that do not start with an underscore.
-
- It does not make sense to use this feature with a non-static local
-variable since such variables do not have assembler names. If you are
-trying to put the variable in a particular register, see *Note Explicit
-Reg Vars::. GCC presently accepts such code with a warning, but will
-probably be changed to issue an error, rather than a warning, in the
-future.
-
- You cannot use `asm' in this way in a function _definition_; but you
-can get the same effect by writing a declaration for the function
-before its definition and putting `asm' there, like this:
-
- extern func () asm ("FUNC");
-
- func (x, y)
- int x, y;
- ...
-
- It is up to you to make sure that the assembler names you choose do
-not conflict with any other assembler symbols. Also, you must not use a
-register name; that would produce completely invalid assembler code.
-GCC does not as yet have the ability to store static variables in
-registers. Perhaps that will be added.
-
-\1f
-File: gcc.info, Node: Explicit Reg Vars, Next: Alternate Keywords, Prev: Asm Labels, Up: C Extensions
-
-Variables in Specified Registers
-================================
-
- GNU C allows you to put a few global variables into specified
-hardware registers. You can also specify the register in which an
-ordinary register variable should be allocated.
-
- * Global register variables reserve registers throughout the program.
- This may be useful in programs such as programming language
- interpreters which have a couple of global variables that are
- accessed very often.
-
- * Local register variables in specific registers do not reserve the
- registers. The compiler's data flow analysis is capable of
- determining where the specified registers contain live values, and
- where they are available for other uses. Stores into local
- register variables may be deleted when they appear to be dead
- according to dataflow analysis. References to local register
- variables may be deleted or moved or simplified.
-
- These local variables are sometimes convenient for use with the
- extended `asm' feature (*note Extended Asm::), if you want to
- write one output of the assembler instruction directly into a
- particular register. (This will work provided the register you
- specify fits the constraints specified for that operand in the
- `asm'.)
-
-* Menu:
-
-* Global Reg Vars::
-* Local Reg Vars::
-
-\1f
-File: gcc.info, Node: Global Reg Vars, Next: Local Reg Vars, Up: Explicit Reg Vars
-
-Defining Global Register Variables
-----------------------------------
-
- You can define a global register variable in GNU C like this:
-
- register int *foo asm ("a5");
-
-Here `a5' is the name of the register which should be used. Choose a
-register which is normally saved and restored by function calls on your
-machine, so that library routines will not clobber it.
-
- Naturally the register name is cpu-dependent, so you would need to
-conditionalize your program according to cpu type. The register `a5'
-would be a good choice on a 68000 for a variable of pointer type. On
-machines with register windows, be sure to choose a "global" register
-that is not affected magically by the function call mechanism.
-
- In addition, operating systems on one type of cpu may differ in how
-they name the registers; then you would need additional conditionals.
-For example, some 68000 operating systems call this register `%a5'.
-
- Eventually there may be a way of asking the compiler to choose a
-register automatically, but first we need to figure out how it should
-choose and how to enable you to guide the choice. No solution is
-evident.
-
- Defining a global register variable in a certain register reserves
-that register entirely for this use, at least within the current
-compilation. The register will not be allocated for any other purpose
-in the functions in the current compilation. The register will not be
-saved and restored by these functions. Stores into this register are
-never deleted even if they would appear to be dead, but references may
-be deleted or moved or simplified.
-
- It is not safe to access the global register variables from signal
-handlers, or from more than one thread of control, because the system
-library routines may temporarily use the register for other things
-(unless you recompile them specially for the task at hand).
-
- It is not safe for one function that uses a global register variable
-to call another such function `foo' by way of a third function `lose'
-that was compiled without knowledge of this variable (i.e. in a
-different source file in which the variable wasn't declared). This is
-because `lose' might save the register and put some other value there.
-For example, you can't expect a global register variable to be
-available in the comparison-function that you pass to `qsort', since
-`qsort' might have put something else in that register. (If you are
-prepared to recompile `qsort' with the same global register variable,
-you can solve this problem.)
-
- If you want to recompile `qsort' or other source files which do not
-actually use your global register variable, so that they will not use
-that register for any other purpose, then it suffices to specify the
-compiler option `-ffixed-REG'. You need not actually add a global
-register declaration to their source code.
-
- A function which can alter the value of a global register variable
-cannot safely be called from a function compiled without this variable,
-because it could clobber the value the caller expects to find there on
-return. Therefore, the function which is the entry point into the part
-of the program that uses the global register variable must explicitly
-save and restore the value which belongs to its caller.
-
- On most machines, `longjmp' will restore to each global register
-variable the value it had at the time of the `setjmp'. On some
-machines, however, `longjmp' will not change the value of global
-register variables. To be portable, the function that called `setjmp'
-should make other arrangements to save the values of the global register
-variables, and to restore them in a `longjmp'. This way, the same
-thing will happen regardless of what `longjmp' does.
-
- All global register variable declarations must precede all function
-definitions. If such a declaration could appear after function
-definitions, the declaration would be too late to prevent the register
-from being used for other purposes in the preceding functions.
-
- Global register variables may not have initial values, because an
-executable file has no means to supply initial contents for a register.
-
- On the Sparc, there are reports that g3 ... g7 are suitable
-registers, but certain library functions, such as `getwd', as well as
-the subroutines for division and remainder, modify g3 and g4. g1 and
-g2 are local temporaries.
-
- On the 68000, a2 ... a5 should be suitable, as should d2 ... d7. Of
-course, it will not do to use more than a few of those.
-
-\1f
-File: gcc.info, Node: Local Reg Vars, Prev: Global Reg Vars, Up: Explicit Reg Vars
-
-Specifying Registers for Local Variables
-----------------------------------------
-
- You can define a local register variable with a specified register
-like this:
-
- register int *foo asm ("a5");
-
-Here `a5' is the name of the register which should be used. Note that
-this is the same syntax used for defining global register variables,
-but for a local variable it would appear within a function.
-
- Naturally the register name is cpu-dependent, but this is not a
-problem, since specific registers are most often useful with explicit
-assembler instructions (*note Extended Asm::). Both of these things
-generally require that you conditionalize your program according to cpu
-type.
-
- In addition, operating systems on one type of cpu may differ in how
-they name the registers; then you would need additional conditionals.
-For example, some 68000 operating systems call this register `%a5'.
-
- Defining such a register variable does not reserve the register; it
-remains available for other uses in places where flow control determines
-the variable's value is not live. However, these registers are made
-unavailable for use in the reload pass; excessive use of this feature
-leaves the compiler too few available registers to compile certain
-functions.
-
- This option does not guarantee that GCC will generate code that has
-this variable in the register you specify at all times. You may not
-code an explicit reference to this register in an `asm' statement and
-assume it will always refer to this variable.
-
- Stores into local register variables may be deleted when they appear
-to be dead according to dataflow analysis. References to local
-register variables may be deleted or moved or simplified.
-
-\1f
-File: gcc.info, Node: Alternate Keywords, Next: Incomplete Enums, Prev: Explicit Reg Vars, Up: C Extensions
-
-Alternate Keywords
-==================
-
- The option `-traditional' disables certain keywords; `-ansi' and the
-various `-std' options disable certain others. This causes trouble
-when you want to use GNU C extensions, or ISO C features, in a
-general-purpose header file that should be usable by all programs,
-including ISO C programs and traditional ones. The keywords `asm',
-`typeof' and `inline' cannot be used since they won't work in a program
-compiled with `-ansi' (although `inline' can be used in a program
-compiled with `-std=c99'), while the keywords `const', `volatile',
-`signed', `typeof' and `inline' won't work in a program compiled with
-`-traditional'. The ISO C99 keyword `restrict' is only available when
-`-std=gnu99' (which will eventually be the default) or `-std=c99' (or
-the equivalent `-std=iso9899:1999') is used.
-
- The way to solve these problems is to put `__' at the beginning and
-end of each problematical keyword. For example, use `__asm__' instead
-of `asm', `__const__' instead of `const', and `__inline__' instead of
-`inline'.
-
- Other C compilers won't accept these alternative keywords; if you
-want to compile with another compiler, you can define the alternate
-keywords as macros to replace them with the customary keywords. It
-looks like this:
-
- #ifndef __GNUC__
- #define __asm__ asm
- #endif
-
- `-pedantic' and other options cause warnings for many GNU C
-extensions. You can prevent such warnings within one expression by
-writing `__extension__' before the expression. `__extension__' has no
-effect aside from this.
-
-\1f
-File: gcc.info, Node: Incomplete Enums, Next: Function Names, Prev: Alternate Keywords, Up: C Extensions
-
-Incomplete `enum' Types
-=======================
-
- You can define an `enum' tag without specifying its possible values.
-This results in an incomplete type, much like what you get if you write
-`struct foo' without describing the elements. A later declaration
-which does specify the possible values completes the type.
-
- You can't allocate variables or storage using the type while it is
-incomplete. However, you can work with pointers to that type.
-
- This extension may not be very useful, but it makes the handling of
-`enum' more consistent with the way `struct' and `union' are handled.
-
- This extension is not supported by GNU C++.
-
-\1f
-File: gcc.info, Node: Function Names, Next: Return Address, Prev: Incomplete Enums, Up: C Extensions
-
-Function Names as Strings
-=========================
-
- GCC predefines two magic identifiers to hold the name of the current
-function. The identifier `__FUNCTION__' holds the name of the function
-as it appears in the source. The identifier `__PRETTY_FUNCTION__'
-holds the name of the function pretty printed in a language specific
-fashion.
-
- These names are always the same in a C function, but in a C++
-function they may be different. For example, this program:
-
- extern "C" {
- extern int printf (char *, ...);
- }
-
- class a {
- public:
- sub (int i)
- {
- printf ("__FUNCTION__ = %s\n", __FUNCTION__);
- printf ("__PRETTY_FUNCTION__ = %s\n", __PRETTY_FUNCTION__);
- }
- };
-
- int
- main (void)
- {
- a ax;
- ax.sub (0);
- return 0;
- }
-
-gives this output:
-
- __FUNCTION__ = sub
- __PRETTY_FUNCTION__ = int a::sub (int)
-
- The compiler automagically replaces the identifiers with a string
-literal containing the appropriate name. Thus, they are neither
-preprocessor macros, like `__FILE__' and `__LINE__', nor variables.
-This means that they catenate with other string literals, and that they
-can be used to initialize char arrays. For example
-
- char here[] = "Function " __FUNCTION__ " in " __FILE__;
-
- On the other hand, `#ifdef __FUNCTION__' does not have any special
-meaning inside a function, since the preprocessor does not do anything
-special with the identifier `__FUNCTION__'.
-
- Note that these semantics are deprecated, and that GCC 3.2 will
-handle `__FUNCTION__' and `__PRETTY_FUNCTION__' the same way as
-`__func__'. `__func__' is defined by the ISO standard C99:
-
- The identifier `__func__' is implicitly declared by the translator
- as if, immediately following the opening brace of each function
- definition, the declaration
- static const char __func__[] = "function-name";
-
- appeared, where function-name is the name of the lexically-enclosing
- function. This name is the unadorned name of the function.
-
- By this definition, `__func__' is a variable, not a string literal.
-In particular, `__func__' does not catenate with other string literals.
-
- In `C++', `__FUNCTION__' and `__PRETTY_FUNCTION__' are variables,
-declared in the same way as `__func__'.
-
-\1f
-File: gcc.info, Node: Return Address, Next: Vector Extensions, Prev: Function Names, Up: C Extensions
-
-Getting the Return or Frame Address of a Function
-=================================================
-
- These functions may be used to get information about the callers of a
-function.
-
- - Built-in Function: void * __builtin_return_address (unsigned int
- LEVEL)
- This function returns the return address of the current function,
- or of one of its callers. The LEVEL argument is number of frames
- to scan up the call stack. A value of `0' yields the return
- address of the current function, a value of `1' yields the return
- address of the caller of the current function, and so forth.
-
- The LEVEL argument must be a constant integer.
-
- On some machines it may be impossible to determine the return
- address of any function other than the current one; in such cases,
- or when the top of the stack has been reached, this function will
- return `0' or a random value. In addition,
- `__builtin_frame_address' may be used to determine if the top of
- the stack has been reached.
-
- This function should only be used with a nonzero argument for
- debugging purposes.
-
- - Built-in Function: void * __builtin_frame_address (unsigned int
- LEVEL)
- This function is similar to `__builtin_return_address', but it
- returns the address of the function frame rather than the return
- address of the function. Calling `__builtin_frame_address' with a
- value of `0' yields the frame address of the current function, a
- value of `1' yields the frame address of the caller of the current
- function, and so forth.
-
- The frame is the area on the stack which holds local variables and
- saved registers. The frame address is normally the address of the
- first word pushed on to the stack by the function. However, the
- exact definition depends upon the processor and the calling
- convention. If the processor has a dedicated frame pointer
- register, and the function has a frame, then
- `__builtin_frame_address' will return the value of the frame
- pointer register.
-
- On some machines it may be impossible to determine the frame
- address of any function other than the current one; in such cases,
- or when the top of the stack has been reached, this function will
- return `0' if the first frame pointer is properly initialized by
- the startup code.
-
- This function should only be used with a nonzero argument for
- debugging purposes.
-
-\1f
-File: gcc.info, Node: Vector Extensions, Next: Other Builtins, Prev: Return Address, Up: C Extensions
-
-Using vector instructions through built-in functions
-====================================================
-
- On some targets, the instruction set contains SIMD vector
-instructions that operate on multiple values contained in one large
-register at the same time. For example, on the i386 the MMX, 3Dnow!
-and SSE extensions can be used this way.
-
- The first step in using these extensions is to provide the necessary
-data types. This should be done using an appropriate `typedef':
-
- typedef int v4si __attribute__ ((mode(V4SI)));
-
- The base type `int' is effectively ignored by the compiler, the
-actual properties of the new type `v4si' are defined by the
-`__attribute__'. It defines the machine mode to be used; for vector
-types these have the form `VNB'; N should be the number of elements in
-the vector, and B should be the base mode of the individual elements.
-The following can be used as base modes:
-
-`QI'
- An integer that is as wide as the smallest addressable unit,
- usually 8 bits.
-
-`HI'
- An integer, twice as wide as a QI mode integer, usually 16 bits.
-
-`SI'
- An integer, four times as wide as a QI mode integer, usually 32
- bits.
-
-`DI'
- An integer, eight times as wide as a QI mode integer, usually 64
- bits.
-
-`SF'
- A floating point value, as wide as a SI mode integer, usually 32
- bits.
-
-`DF'
- A floating point value, as wide as a DI mode integer, usually 64
- bits.
-
- Not all base types or combinations are always valid; which modes can
-be used is determined by the target machine. For example, if
-targetting the i386 MMX extensions, only `V8QI', `V4HI' and `V2SI' are
-allowed modes.
-
- There are no `V1xx' vector modes - they would be identical to the
-corresponding base mode.
-
- There is no distinction between signed and unsigned vector modes.
-This distinction is made by the operations that perform on the vectors,
-not by the data type.
-
- The types defined in this manner are somewhat special, they cannot be
-used with most normal C operations (i.e., a vector addition can _not_
-be represented by a normal addition of two vector type variables). You
-can declare only variables and use them in function calls and returns,
-as well as in assignments and some casts. It is possible to cast from
-one vector type to another, provided they are of the same size (in
-fact, you can also cast vectors to and from other datatypes of the same
-size).
-
- A port that supports vector operations provides a set of built-in
-functions that can be used to operate on vectors. For example, a
-function to add two vectors and multiply the result by a third could
-look like this:
-
- v4si f (v4si a, v4si b, v4si c)
- {
- v4si tmp = __builtin_addv4si (a, b);
- return __builtin_mulv4si (tmp, c);
- }
-
-\1f
-File: gcc.info, Node: Other Builtins, Next: Target Builtins, Prev: Vector Extensions, Up: C Extensions
-
-Other built-in functions provided by GCC
-========================================
-
- GCC provides a large number of built-in functions other than the ones
-mentioned above. Some of these are for internal use in the processing
-of exceptions or variable-length argument lists and will not be
-documented here because they may change from time to time; we do not
-recommend general use of these functions.
-
- The remaining functions are provided for optimization purposes.
-
- GCC includes built-in versions of many of the functions in the
-standard C library. The versions prefixed with `__builtin_' will
-always be treated as having the same meaning as the C library function
-even if you specify the `-fno-builtin' option. (*note C Dialect
-Options::) Many of these functions are only optimized in certain cases;
-if they are not optimized in a particular case, a call to the library
-function will be emitted.
-
- The functions `abort', `exit', `_Exit' and `_exit' are recognized
-and presumed not to return, but otherwise are not built in. `_exit' is
-not recognized in strict ISO C mode (`-ansi', `-std=c89' or
-`-std=c99'). `_Exit' is not recognized in strict C89 mode (`-ansi' or
-`-std=c89').
-
- Outside strict ISO C mode, the functions `alloca', `bcmp', `bzero',
-`index', `rindex', `ffs', `fputs_unlocked', `printf_unlocked' and
-`fprintf_unlocked' may be handled as built-in functions. All these
-functions have corresponding versions prefixed with `__builtin_', which
-may be used even in strict C89 mode.
-
- The ISO C99 functions `conj', `conjf', `conjl', `creal', `crealf',
-`creall', `cimag', `cimagf', `cimagl', `llabs' and `imaxabs' are
-handled as built-in functions except in strict ISO C89 mode. There are
-also built-in versions of the ISO C99 functions `cosf', `cosl',
-`fabsf', `fabsl', `sinf', `sinl', `sqrtf', and `sqrtl', that are
-recognized in any mode since ISO C89 reserves these names for the
-purpose to which ISO C99 puts them. All these functions have
-corresponding versions prefixed with `__builtin_'.
-
- The ISO C89 functions `abs', `cos', `fabs', `fprintf', `fputs',
-`labs', `memcmp', `memcpy', `memset', `printf', `sin', `sqrt', `strcat',
-`strchr', `strcmp', `strcpy', `strcspn', `strlen', `strncat',
-`strncmp', `strncpy', `strpbrk', `strrchr', `strspn', and `strstr' are
-all recognized as built-in functions unless `-fno-builtin' is specified
-(or `-fno-builtin-FUNCTION' is specified for an individual function).
-All of these functions have corresponding versions prefixed with
-`__builtin_'.
-
- GCC provides built-in versions of the ISO C99 floating point
-comparison macros that avoid raising exceptions for unordered operands.
-They have the same names as the standard macros ( `isgreater',
-`isgreaterequal', `isless', `islessequal', `islessgreater', and
-`isunordered') , with `__builtin_' prefixed. We intend for a library
-implementor to be able to simply `#define' each standard macro to its
-built-in equivalent.
-
- - Built-in Function: int __builtin_types_compatible_p (TYPE1, TYPE2)
- You can use the built-in function `__builtin_types_compatible_p' to
- determine whether two types are the same.
-
- This built-in function returns 1 if the unqualified versions of the
- types TYPE1 and TYPE2 (which are types, not expressions) are
- compatible, 0 otherwise. The result of this built-in function can
- be used in integer constant expressions.
-
- This built-in function ignores top level qualifiers (e.g., `const',
- `volatile'). For example, `int' is equivalent to `const int'.
-
- The type `int[]' and `int[5]' are compatible. On the other hand,
- `int' and `char *' are not compatible, even if the size of their
- types, on the particular architecture are the same. Also, the
- amount of pointer indirection is taken into account when
- determining similarity. Consequently, `short *' is not similar to
- `short **'. Furthermore, two types that are typedefed are
- considered compatible if their underlying types are compatible.
-
- An `enum' type is considered to be compatible with another `enum'
- type. For example, `enum {foo, bar}' is similar to `enum {hot,
- dog}'.
-
- You would typically use this function in code whose execution
- varies depending on the arguments' types. For example:
-
- #define foo(x) \
- ({ \
- typeof (x) tmp; \
- if (__builtin_types_compatible_p (typeof (x), long double)) \
- tmp = foo_long_double (tmp); \
- else if (__builtin_types_compatible_p (typeof (x), double)) \
- tmp = foo_double (tmp); \
- else if (__builtin_types_compatible_p (typeof (x), float)) \
- tmp = foo_float (tmp); \
- else \
- abort (); \
- tmp; \
- })
-
- _Note:_ This construct is only available for C.
-
-
- - Built-in Function: TYPE __builtin_choose_expr (CONST_EXP, EXP1, EXP2)
- You can use the built-in function `__builtin_choose_expr' to
- evaluate code depending on the value of a constant expression.
- This built-in function returns EXP1 if CONST_EXP, which is a
- constant expression that must be able to be determined at compile
- time, is nonzero. Otherwise it returns 0.
-
- This built-in function is analogous to the `? :' operator in C,
- except that the expression returned has its type unaltered by
- promotion rules. Also, the built-in function does not evaluate
- the expression that was not chosen. For example, if CONST_EXP
- evaluates to true, EXP2 is not evaluated even if it has
- side-effects.
-
- This built-in function can return an lvalue if the chosen argument
- is an lvalue.
-
- If EXP1 is returned, the return type is the same as EXP1's type.
- Similarly, if EXP2 is returned, its return type is the same as
- EXP2.
-
- Example:
-
- #define foo(x) \
- __builtin_choose_expr (__builtin_types_compatible_p (typeof (x), double), \
- foo_double (x), \
- __builtin_choose_expr (__builtin_types_compatible_p (typeof (x), float), \
- foo_float (x), \
- /* The void expression results in a compile-time error \
- when assigning the result to something. */ \
- (void)0))
-
- _Note:_ This construct is only available for C. Furthermore, the
- unused expression (EXP1 or EXP2 depending on the value of
- CONST_EXP) may still generate syntax errors. This may change in
- future revisions.
-
-
- - Built-in Function: int __builtin_constant_p (EXP)
- You can use the built-in function `__builtin_constant_p' to
- determine if a value is known to be constant at compile-time and
- hence that GCC can perform constant-folding on expressions
- involving that value. The argument of the function is the value
- to test. The function returns the integer 1 if the argument is
- known to be a compile-time constant and 0 if it is not known to be
- a compile-time constant. A return of 0 does not indicate that the
- value is _not_ a constant, but merely that GCC cannot prove it is
- a constant with the specified value of the `-O' option.
-
- You would typically use this function in an embedded application
- where memory was a critical resource. If you have some complex
- calculation, you may want it to be folded if it involves
- constants, but need to call a function if it does not. For
- example:
-
- #define Scale_Value(X) \
- (__builtin_constant_p (X) \
- ? ((X) * SCALE + OFFSET) : Scale (X))
-
- You may use this built-in function in either a macro or an inline
- function. However, if you use it in an inlined function and pass
- an argument of the function as the argument to the built-in, GCC
- will never return 1 when you call the inline function with a
- string constant or compound literal (*note Compound Literals::)
- and will not return 1 when you pass a constant numeric value to
- the inline function unless you specify the `-O' option.
-
- You may also use `__builtin_constant_p' in initializers for static
- data. For instance, you can write
-
- static const int table[] = {
- __builtin_constant_p (EXPRESSION) ? (EXPRESSION) : -1,
- /* ... */
- };
-
- This is an acceptable initializer even if EXPRESSION is not a
- constant expression. GCC must be more conservative about
- evaluating the built-in in this case, because it has no
- opportunity to perform optimization.
-
- Previous versions of GCC did not accept this built-in in data
- initializers. The earliest version where it is completely safe is
- 3.0.1.
-
- - Built-in Function: long __builtin_expect (long EXP, long C)
- You may use `__builtin_expect' to provide the compiler with branch
- prediction information. In general, you should prefer to use
- actual profile feedback for this (`-fprofile-arcs'), as
- programmers are notoriously bad at predicting how their programs
- actually perform. However, there are applications in which this
- data is hard to collect.
-
- The return value is the value of EXP, which should be an integral
- expression. The value of C must be a compile-time constant. The
- semantics of the built-in are that it is expected that EXP == C.
- For example:
-
- if (__builtin_expect (x, 0))
- foo ();
-
- would indicate that we do not expect to call `foo', since we
- expect `x' to be zero. Since you are limited to integral
- expressions for EXP, you should use constructions such as
-
- if (__builtin_expect (ptr != NULL, 1))
- error ();
-
- when testing pointer or floating-point values.
-
- - Built-in Function: void __builtin_prefetch (const void *ADDR, ...)
- This function is used to minimize cache-miss latency by moving
- data into a cache before it is accessed. You can insert calls to
- `__builtin_prefetch' into code for which you know addresses of
- data in memory that is likely to be accessed soon. If the target
- supports them, data prefetch instructions will be generated. If
- the prefetch is done early enough before the access then the data
- will be in the cache by the time it is accessed.
-
- The value of ADDR is the address of the memory to prefetch. There
- are two optional arguments, RW and LOCALITY. The value of RW is a
- compile-time constant one or zero; one means that the prefetch is
- preparing for a write to the memory address and zero, the default,
- means that the prefetch is preparing for a read. The value
- LOCALITY must be a compile-time constant integer between zero and
- three. A value of zero means that the data has no temporal
- locality, so it need not be left in the cache after the access. A
- value of three means that the data has a high degree of temporal
- locality and should be left in all levels of cache possible.
- Values of one and two mean, respectively, a low or moderate degree
- of temporal locality. The default is three.
-
- for (i = 0; i < n; i++)
- {
- a[i] = a[i] + b[i];
- __builtin_prefetch (&a[i+j], 1, 1);
- __builtin_prefetch (&b[i+j], 0, 1);
- /* ... */
- }
-
- Data prefetch does not generate faults if ADDR is invalid, but the
- address expression itself must be valid. For example, a prefetch
- of `p->next' will not fault if `p->next' is not a valid address,
- but evaluation will fault if `p' is not a valid address.
-
- If the target does not support data prefetch, the address
- expression is evaluated if it includes side effects but no other
- code is generated and GCC does not issue a warning.
-
-\1f
-File: gcc.info, Node: Target Builtins, Next: Pragmas, Prev: Other Builtins, Up: C Extensions
-
-Built-in Functions Specific to Particular Target Machines
-=========================================================
-
- On some target machines, GCC supports many built-in functions
-specific to those machines. Generally these generate calls to specific
-machine instructions, but allow the compiler to schedule those calls.
-
-* Menu:
-
-* X86 Built-in Functions::
-* PowerPC AltiVec Built-in Functions::
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: X86 Built-in Functions, Next: PowerPC AltiVec Built-in Functions, Up: Target Builtins
-
-X86 Built-in Functions
-----------------------
-
- These built-in functions are available for the i386 and x86-64 family
-of computers, depending on the command-line switches used.
-
- The following machine modes are available for use with MMX built-in
-functions (*note Vector Extensions::): `V2SI' for a vector of two
-32-bit integers, `V4HI' for a vector of four 16-bit integers, and
-`V8QI' for a vector of eight 8-bit integers. Some of the built-in
-functions operate on MMX registers as a whole 64-bit entity, these use
-`DI' as their mode.
-
- If 3Dnow extensions are enabled, `V2SF' is used as a mode for a
-vector of two 32-bit floating point values.
-
- If SSE extensions are enabled, `V4SF' is used for a vector of four
-32-bit floating point values. Some instructions use a vector of four
-32-bit integers, these use `V4SI'. Finally, some instructions operate
-on an entire vector register, interpreting it as a 128-bit integer,
-these use mode `TI'.
-
- The following built-in functions are made available by `-mmmx'. All
-of them generate the machine instruction that is part of the name.
-
- v8qi __builtin_ia32_paddb (v8qi, v8qi)
- v4hi __builtin_ia32_paddw (v4hi, v4hi)
- v2si __builtin_ia32_paddd (v2si, v2si)
- v8qi __builtin_ia32_psubb (v8qi, v8qi)
- v4hi __builtin_ia32_psubw (v4hi, v4hi)
- v2si __builtin_ia32_psubd (v2si, v2si)
- v8qi __builtin_ia32_paddsb (v8qi, v8qi)
- v4hi __builtin_ia32_paddsw (v4hi, v4hi)
- v8qi __builtin_ia32_psubsb (v8qi, v8qi)
- v4hi __builtin_ia32_psubsw (v4hi, v4hi)
- v8qi __builtin_ia32_paddusb (v8qi, v8qi)
- v4hi __builtin_ia32_paddusw (v4hi, v4hi)
- v8qi __builtin_ia32_psubusb (v8qi, v8qi)
- v4hi __builtin_ia32_psubusw (v4hi, v4hi)
- v4hi __builtin_ia32_pmullw (v4hi, v4hi)
- v4hi __builtin_ia32_pmulhw (v4hi, v4hi)
- di __builtin_ia32_pand (di, di)
- di __builtin_ia32_pandn (di,di)
- di __builtin_ia32_por (di, di)
- di __builtin_ia32_pxor (di, di)
- v8qi __builtin_ia32_pcmpeqb (v8qi, v8qi)
- v4hi __builtin_ia32_pcmpeqw (v4hi, v4hi)
- v2si __builtin_ia32_pcmpeqd (v2si, v2si)
- v8qi __builtin_ia32_pcmpgtb (v8qi, v8qi)
- v4hi __builtin_ia32_pcmpgtw (v4hi, v4hi)
- v2si __builtin_ia32_pcmpgtd (v2si, v2si)
- v8qi __builtin_ia32_punpckhbw (v8qi, v8qi)
- v4hi __builtin_ia32_punpckhwd (v4hi, v4hi)
- v2si __builtin_ia32_punpckhdq (v2si, v2si)
- v8qi __builtin_ia32_punpcklbw (v8qi, v8qi)
- v4hi __builtin_ia32_punpcklwd (v4hi, v4hi)
- v2si __builtin_ia32_punpckldq (v2si, v2si)
- v8qi __builtin_ia32_packsswb (v4hi, v4hi)
- v4hi __builtin_ia32_packssdw (v2si, v2si)
- v8qi __builtin_ia32_packuswb (v4hi, v4hi)
-
- The following built-in functions are made available either with
-`-msse', or with a combination of `-m3dnow' and `-march=athlon'. All
-of them generate the machine instruction that is part of the name.
-
- v4hi __builtin_ia32_pmulhuw (v4hi, v4hi)
- v8qi __builtin_ia32_pavgb (v8qi, v8qi)
- v4hi __builtin_ia32_pavgw (v4hi, v4hi)
- v4hi __builtin_ia32_psadbw (v8qi, v8qi)
- v8qi __builtin_ia32_pmaxub (v8qi, v8qi)
- v4hi __builtin_ia32_pmaxsw (v4hi, v4hi)
- v8qi __builtin_ia32_pminub (v8qi, v8qi)
- v4hi __builtin_ia32_pminsw (v4hi, v4hi)
- int __builtin_ia32_pextrw (v4hi, int)
- v4hi __builtin_ia32_pinsrw (v4hi, int, int)
- int __builtin_ia32_pmovmskb (v8qi)
- void __builtin_ia32_maskmovq (v8qi, v8qi, char *)
- void __builtin_ia32_movntq (di *, di)
- void __builtin_ia32_sfence (void)
-
- The following built-in functions are available when `-msse' is used.
-All of them generate the machine instruction that is part of the name.
-
- int __builtin_ia32_comieq (v4sf, v4sf)
- int __builtin_ia32_comineq (v4sf, v4sf)
- int __builtin_ia32_comilt (v4sf, v4sf)
- int __builtin_ia32_comile (v4sf, v4sf)
- int __builtin_ia32_comigt (v4sf, v4sf)
- int __builtin_ia32_comige (v4sf, v4sf)
- int __builtin_ia32_ucomieq (v4sf, v4sf)
- int __builtin_ia32_ucomineq (v4sf, v4sf)
- int __builtin_ia32_ucomilt (v4sf, v4sf)
- int __builtin_ia32_ucomile (v4sf, v4sf)
- int __builtin_ia32_ucomigt (v4sf, v4sf)
- int __builtin_ia32_ucomige (v4sf, v4sf)
- v4sf __builtin_ia32_addps (v4sf, v4sf)
- v4sf __builtin_ia32_subps (v4sf, v4sf)
- v4sf __builtin_ia32_mulps (v4sf, v4sf)
- v4sf __builtin_ia32_divps (v4sf, v4sf)
- v4sf __builtin_ia32_addss (v4sf, v4sf)
- v4sf __builtin_ia32_subss (v4sf, v4sf)
- v4sf __builtin_ia32_mulss (v4sf, v4sf)
- v4sf __builtin_ia32_divss (v4sf, v4sf)
- v4si __builtin_ia32_cmpeqps (v4sf, v4sf)
- v4si __builtin_ia32_cmpltps (v4sf, v4sf)
- v4si __builtin_ia32_cmpleps (v4sf, v4sf)
- v4si __builtin_ia32_cmpgtps (v4sf, v4sf)
- v4si __builtin_ia32_cmpgeps (v4sf, v4sf)
- v4si __builtin_ia32_cmpunordps (v4sf, v4sf)
- v4si __builtin_ia32_cmpneqps (v4sf, v4sf)
- v4si __builtin_ia32_cmpnltps (v4sf, v4sf)
- v4si __builtin_ia32_cmpnleps (v4sf, v4sf)
- v4si __builtin_ia32_cmpngtps (v4sf, v4sf)
- v4si __builtin_ia32_cmpngeps (v4sf, v4sf)
- v4si __builtin_ia32_cmpordps (v4sf, v4sf)
- v4si __builtin_ia32_cmpeqss (v4sf, v4sf)
- v4si __builtin_ia32_cmpltss (v4sf, v4sf)
- v4si __builtin_ia32_cmpless (v4sf, v4sf)
- v4si __builtin_ia32_cmpgtss (v4sf, v4sf)
- v4si __builtin_ia32_cmpgess (v4sf, v4sf)
- v4si __builtin_ia32_cmpunordss (v4sf, v4sf)
- v4si __builtin_ia32_cmpneqss (v4sf, v4sf)
- v4si __builtin_ia32_cmpnlts (v4sf, v4sf)
- v4si __builtin_ia32_cmpnless (v4sf, v4sf)
- v4si __builtin_ia32_cmpngtss (v4sf, v4sf)
- v4si __builtin_ia32_cmpngess (v4sf, v4sf)
- v4si __builtin_ia32_cmpordss (v4sf, v4sf)
- v4sf __builtin_ia32_maxps (v4sf, v4sf)
- v4sf __builtin_ia32_maxss (v4sf, v4sf)
- v4sf __builtin_ia32_minps (v4sf, v4sf)
- v4sf __builtin_ia32_minss (v4sf, v4sf)
- v4sf __builtin_ia32_andps (v4sf, v4sf)
- v4sf __builtin_ia32_andnps (v4sf, v4sf)
- v4sf __builtin_ia32_orps (v4sf, v4sf)
- v4sf __builtin_ia32_xorps (v4sf, v4sf)
- v4sf __builtin_ia32_movss (v4sf, v4sf)
- v4sf __builtin_ia32_movhlps (v4sf, v4sf)
- v4sf __builtin_ia32_movlhps (v4sf, v4sf)
- v4sf __builtin_ia32_unpckhps (v4sf, v4sf)
- v4sf __builtin_ia32_unpcklps (v4sf, v4sf)
- v4sf __builtin_ia32_cvtpi2ps (v4sf, v2si)
- v4sf __builtin_ia32_cvtsi2ss (v4sf, int)
- v2si __builtin_ia32_cvtps2pi (v4sf)
- int __builtin_ia32_cvtss2si (v4sf)
- v2si __builtin_ia32_cvttps2pi (v4sf)
- int __builtin_ia32_cvttss2si (v4sf)
- v4sf __builtin_ia32_rcpps (v4sf)
- v4sf __builtin_ia32_rsqrtps (v4sf)
- v4sf __builtin_ia32_sqrtps (v4sf)
- v4sf __builtin_ia32_rcpss (v4sf)
- v4sf __builtin_ia32_rsqrtss (v4sf)
- v4sf __builtin_ia32_sqrtss (v4sf)
- v4sf __builtin_ia32_shufps (v4sf, v4sf, int)
- void __builtin_ia32_movntps (float *, v4sf)
- int __builtin_ia32_movmskps (v4sf)
-
- The following built-in functions are available when `-msse' is used.
-
-`v4sf __builtin_ia32_loadaps (float *)'
- Generates the `movaps' machine instruction as a load from memory.
-
-`void __builtin_ia32_storeaps (float *, v4sf)'
- Generates the `movaps' machine instruction as a store to memory.
-
-`v4sf __builtin_ia32_loadups (float *)'
- Generates the `movups' machine instruction as a load from memory.
-
-`void __builtin_ia32_storeups (float *, v4sf)'
- Generates the `movups' machine instruction as a store to memory.
-
-`v4sf __builtin_ia32_loadsss (float *)'
- Generates the `movss' machine instruction as a load from memory.
-
-`void __builtin_ia32_storess (float *, v4sf)'
- Generates the `movss' machine instruction as a store to memory.
-
-`v4sf __builtin_ia32_loadhps (v4sf, v2si *)'
- Generates the `movhps' machine instruction as a load from memory.
-
-`v4sf __builtin_ia32_loadlps (v4sf, v2si *)'
- Generates the `movlps' machine instruction as a load from memory
-
-`void __builtin_ia32_storehps (v4sf, v2si *)'
- Generates the `movhps' machine instruction as a store to memory.
-
-`void __builtin_ia32_storelps (v4sf, v2si *)'
- Generates the `movlps' machine instruction as a store to memory.
-
- The following built-in functions are available when `-m3dnow' is
-used. All of them generate the machine instruction that is part of the
-name.
-
- void __builtin_ia32_femms (void)
- v8qi __builtin_ia32_pavgusb (v8qi, v8qi)
- v2si __builtin_ia32_pf2id (v2sf)
- v2sf __builtin_ia32_pfacc (v2sf, v2sf)
- v2sf __builtin_ia32_pfadd (v2sf, v2sf)
- v2si __builtin_ia32_pfcmpeq (v2sf, v2sf)
- v2si __builtin_ia32_pfcmpge (v2sf, v2sf)
- v2si __builtin_ia32_pfcmpgt (v2sf, v2sf)
- v2sf __builtin_ia32_pfmax (v2sf, v2sf)
- v2sf __builtin_ia32_pfmin (v2sf, v2sf)
- v2sf __builtin_ia32_pfmul (v2sf, v2sf)
- v2sf __builtin_ia32_pfrcp (v2sf)
- v2sf __builtin_ia32_pfrcpit1 (v2sf, v2sf)
- v2sf __builtin_ia32_pfrcpit2 (v2sf, v2sf)
- v2sf __builtin_ia32_pfrsqrt (v2sf)
- v2sf __builtin_ia32_pfrsqrtit1 (v2sf, v2sf)
- v2sf __builtin_ia32_pfsub (v2sf, v2sf)
- v2sf __builtin_ia32_pfsubr (v2sf, v2sf)
- v2sf __builtin_ia32_pi2fd (v2si)
- v4hi __builtin_ia32_pmulhrw (v4hi, v4hi)
-
- The following built-in functions are available when both `-m3dnow'
-and `-march=athlon' are used. All of them generate the machine
-instruction that is part of the name.
-
- v2si __builtin_ia32_pf2iw (v2sf)
- v2sf __builtin_ia32_pfnacc (v2sf, v2sf)
- v2sf __builtin_ia32_pfpnacc (v2sf, v2sf)
- v2sf __builtin_ia32_pi2fw (v2si)
- v2sf __builtin_ia32_pswapdsf (v2sf)
- v2si __builtin_ia32_pswapdsi (v2si)
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: PowerPC AltiVec Built-in Functions, Prev: X86 Built-in Functions, Up: Target Builtins
-
-PowerPC AltiVec Built-in Functions
-----------------------------------
-
- These built-in functions are available for the PowerPC family of
-computers, depending on the command-line switches used.
-
- The following machine modes are available for use with AltiVec
-built-in functions (*note Vector Extensions::): `V4SI' for a vector of
-four 32-bit integers, `V4SF' for a vector of four 32-bit floating point
-numbers, `V8HI' for a vector of eight 16-bit integers, and `V16QI' for
-a vector of sixteen 8-bit integers.
-
- The following functions are made available by including
-`<altivec.h>' and using `-maltivec' and `-mabi=altivec'. The functions
-implement the functionality described in Motorola's AltiVec Programming
-Interface Manual.
-
- _Note:_ Only the `<altivec.h>' interface is supported. Internally,
-GCC uses built-in functions to achieve the functionality in the
-aforementioned header file, but they are not supported and are subject
-to change without notice.
-
- vector signed char vec_abs (vector signed char, vector signed char);
- vector signed short vec_abs (vector signed short, vector signed short);
- vector signed int vec_abs (vector signed int, vector signed int);
- vector signed float vec_abs (vector signed float, vector signed float);
-
- vector signed char vec_abss (vector signed char, vector signed char);
- vector signed short vec_abss (vector signed short, vector signed short);
-
- vector signed char vec_add (vector signed char, vector signed char);
- vector unsigned char vec_add (vector signed char, vector unsigned char);
-
- vector unsigned char vec_add (vector unsigned char, vector signed char);
-
- vector unsigned char vec_add (vector unsigned char,
- vector unsigned char);
- vector signed short vec_add (vector signed short, vector signed short);
- vector unsigned short vec_add (vector signed short,
- vector unsigned short);
- vector unsigned short vec_add (vector unsigned short,
- vector signed short);
- vector unsigned short vec_add (vector unsigned short,
- vector unsigned short);
- vector signed int vec_add (vector signed int, vector signed int);
- vector unsigned int vec_add (vector signed int, vector unsigned int);
- vector unsigned int vec_add (vector unsigned int, vector signed int);
- vector unsigned int vec_add (vector unsigned int, vector unsigned int);
- vector float vec_add (vector float, vector float);
-
- vector unsigned int vec_addc (vector unsigned int, vector unsigned int);
-
- vector unsigned char vec_adds (vector signed char,
- vector unsigned char);
- vector unsigned char vec_adds (vector unsigned char,
- vector signed char);
- vector unsigned char vec_adds (vector unsigned char,
- vector unsigned char);
- vector signed char vec_adds (vector signed char, vector signed char);
- vector unsigned short vec_adds (vector signed short,
- vector unsigned short);
- vector unsigned short vec_adds (vector unsigned short,
- vector signed short);
- vector unsigned short vec_adds (vector unsigned short,
- vector unsigned short);
- vector signed short vec_adds (vector signed short, vector signed short);
-
- vector unsigned int vec_adds (vector signed int, vector unsigned int);
- vector unsigned int vec_adds (vector unsigned int, vector signed int);
- vector unsigned int vec_adds (vector unsigned int, vector unsigned int);
-
- vector signed int vec_adds (vector signed int, vector signed int);
-
- vector float vec_and (vector float, vector float);
- vector float vec_and (vector float, vector signed int);
- vector float vec_and (vector signed int, vector float);
- vector signed int vec_and (vector signed int, vector signed int);
- vector unsigned int vec_and (vector signed int, vector unsigned int);
- vector unsigned int vec_and (vector unsigned int, vector signed int);
- vector unsigned int vec_and (vector unsigned int, vector unsigned int);
- vector signed short vec_and (vector signed short, vector signed short);
- vector unsigned short vec_and (vector signed short,
- vector unsigned short);
- vector unsigned short vec_and (vector unsigned short,
- vector signed short);
- vector unsigned short vec_and (vector unsigned short,
- vector unsigned short);
- vector signed char vec_and (vector signed char, vector signed char);
- vector unsigned char vec_and (vector signed char, vector unsigned char);
-
- vector unsigned char vec_and (vector unsigned char, vector signed char);
-
- vector unsigned char vec_and (vector unsigned char,
- vector unsigned char);
-
- vector float vec_andc (vector float, vector float);
- vector float vec_andc (vector float, vector signed int);
- vector float vec_andc (vector signed int, vector float);
- vector signed int vec_andc (vector signed int, vector signed int);
- vector unsigned int vec_andc (vector signed int, vector unsigned int);
- vector unsigned int vec_andc (vector unsigned int, vector signed int);
- vector unsigned int vec_andc (vector unsigned int, vector unsigned int);
-
- vector signed short vec_andc (vector signed short, vector signed short);
-
- vector unsigned short vec_andc (vector signed short,
- vector unsigned short);
- vector unsigned short vec_andc (vector unsigned short,
- vector signed short);
- vector unsigned short vec_andc (vector unsigned short,
- vector unsigned short);
- vector signed char vec_andc (vector signed char, vector signed char);
- vector unsigned char vec_andc (vector signed char,
- vector unsigned char);
- vector unsigned char vec_andc (vector unsigned char,
- vector signed char);
- vector unsigned char vec_andc (vector unsigned char,
- vector unsigned char);
-
- vector unsigned char vec_avg (vector unsigned char,
- vector unsigned char);
- vector signed char vec_avg (vector signed char, vector signed char);
- vector unsigned short vec_avg (vector unsigned short,
- vector unsigned short);
- vector signed short vec_avg (vector signed short, vector signed short);
- vector unsigned int vec_avg (vector unsigned int, vector unsigned int);
- vector signed int vec_avg (vector signed int, vector signed int);
-
- vector float vec_ceil (vector float);
-
- vector signed int vec_cmpb (vector float, vector float);
-
- vector signed char vec_cmpeq (vector signed char, vector signed char);
- vector signed char vec_cmpeq (vector unsigned char,
- vector unsigned char);
- vector signed short vec_cmpeq (vector signed short,
- vector signed short);
- vector signed short vec_cmpeq (vector unsigned short,
- vector unsigned short);
- vector signed int vec_cmpeq (vector signed int, vector signed int);
- vector signed int vec_cmpeq (vector unsigned int, vector unsigned int);
- vector signed int vec_cmpeq (vector float, vector float);
-
- vector signed int vec_cmpge (vector float, vector float);
-
- vector signed char vec_cmpgt (vector unsigned char,
- vector unsigned char);
- vector signed char vec_cmpgt (vector signed char, vector signed char);
- vector signed short vec_cmpgt (vector unsigned short,
- vector unsigned short);
- vector signed short vec_cmpgt (vector signed short,
- vector signed short);
- vector signed int vec_cmpgt (vector unsigned int, vector unsigned int);
- vector signed int vec_cmpgt (vector signed int, vector signed int);
- vector signed int vec_cmpgt (vector float, vector float);
-
- vector signed int vec_cmple (vector float, vector float);
-
- vector signed char vec_cmplt (vector unsigned char,
- vector unsigned char);
- vector signed char vec_cmplt (vector signed char, vector signed char);
- vector signed short vec_cmplt (vector unsigned short,
- vector unsigned short);
- vector signed short vec_cmplt (vector signed short,
- vector signed short);
- vector signed int vec_cmplt (vector unsigned int, vector unsigned int);
- vector signed int vec_cmplt (vector signed int, vector signed int);
- vector signed int vec_cmplt (vector float, vector float);
-
- vector float vec_ctf (vector unsigned int, const char);
- vector float vec_ctf (vector signed int, const char);
-
- vector signed int vec_cts (vector float, const char);
-
- vector unsigned int vec_ctu (vector float, const char);
-
- void vec_dss (const char);
-
- void vec_dssall (void);
-
- void vec_dst (void *, int, const char);
-
- void vec_dstst (void *, int, const char);
-
- void vec_dststt (void *, int, const char);
-
- void vec_dstt (void *, int, const char);
-
- vector float vec_expte (vector float, vector float);
-
- vector float vec_floor (vector float, vector float);
-
- vector float vec_ld (int, vector float *);
- vector float vec_ld (int, float *):
- vector signed int vec_ld (int, int *);
- vector signed int vec_ld (int, vector signed int *);
- vector unsigned int vec_ld (int, vector unsigned int *);
- vector unsigned int vec_ld (int, unsigned int *);
- vector signed short vec_ld (int, short *, vector signed short *);
- vector unsigned short vec_ld (int, unsigned short *,
- vector unsigned short *);
- vector signed char vec_ld (int, signed char *);
- vector signed char vec_ld (int, vector signed char *);
- vector unsigned char vec_ld (int, unsigned char *);
- vector unsigned char vec_ld (int, vector unsigned char *);
-
- vector signed char vec_lde (int, signed char *);
- vector unsigned char vec_lde (int, unsigned char *);
- vector signed short vec_lde (int, short *);
- vector unsigned short vec_lde (int, unsigned short *);
- vector float vec_lde (int, float *);
- vector signed int vec_lde (int, int *);
- vector unsigned int vec_lde (int, unsigned int *);
-
- void float vec_ldl (int, float *);
- void float vec_ldl (int, vector float *);
- void signed int vec_ldl (int, vector signed int *);
- void signed int vec_ldl (int, int *);
- void unsigned int vec_ldl (int, unsigned int *);
- void unsigned int vec_ldl (int, vector unsigned int *);
- void signed short vec_ldl (int, vector signed short *);
- void signed short vec_ldl (int, short *);
- void unsigned short vec_ldl (int, vector unsigned short *);
- void unsigned short vec_ldl (int, unsigned short *);
- void signed char vec_ldl (int, vector signed char *);
- void signed char vec_ldl (int, signed char *);
- void unsigned char vec_ldl (int, vector unsigned char *);
- void unsigned char vec_ldl (int, unsigned char *);
-
- vector float vec_loge (vector float);
-
- vector unsigned char vec_lvsl (int, void *, int *);
-
- vector unsigned char vec_lvsr (int, void *, int *);
-
- vector float vec_madd (vector float, vector float, vector float);
-
- vector signed short vec_madds (vector signed short, vector signed short,
- vector signed short);
-
- vector unsigned char vec_max (vector signed char, vector unsigned char);
-
- vector unsigned char vec_max (vector unsigned char, vector signed char);
-
- vector unsigned char vec_max (vector unsigned char,
- vector unsigned char);
- vector signed char vec_max (vector signed char, vector signed char);
- vector unsigned short vec_max (vector signed short,
- vector unsigned short);
- vector unsigned short vec_max (vector unsigned short,
- vector signed short);
- vector unsigned short vec_max (vector unsigned short,
- vector unsigned short);
- vector signed short vec_max (vector signed short, vector signed short);
- vector unsigned int vec_max (vector signed int, vector unsigned int);
- vector unsigned int vec_max (vector unsigned int, vector signed int);
- vector unsigned int vec_max (vector unsigned int, vector unsigned int);
- vector signed int vec_max (vector signed int, vector signed int);
- vector float vec_max (vector float, vector float);
-
- vector signed char vec_mergeh (vector signed char, vector signed char);
- vector unsigned char vec_mergeh (vector unsigned char,
- vector unsigned char);
- vector signed short vec_mergeh (vector signed short,
- vector signed short);
- vector unsigned short vec_mergeh (vector unsigned short,
- vector unsigned short);
- vector float vec_mergeh (vector float, vector float);
- vector signed int vec_mergeh (vector signed int, vector signed int);
- vector unsigned int vec_mergeh (vector unsigned int,
- vector unsigned int);
-
- vector signed char vec_mergel (vector signed char, vector signed char);
- vector unsigned char vec_mergel (vector unsigned char,
- vector unsigned char);
- vector signed short vec_mergel (vector signed short,
- vector signed short);
- vector unsigned short vec_mergel (vector unsigned short,
- vector unsigned short);
- vector float vec_mergel (vector float, vector float);
- vector signed int vec_mergel (vector signed int, vector signed int);
- vector unsigned int vec_mergel (vector unsigned int,
- vector unsigned int);
-
- vector unsigned short vec_mfvscr (void);
-
- vector unsigned char vec_min (vector signed char, vector unsigned char);
-
- vector unsigned char vec_min (vector unsigned char, vector signed char);
-
- vector unsigned char vec_min (vector unsigned char,
- vector unsigned char);
- vector signed char vec_min (vector signed char, vector signed char);
- vector unsigned short vec_min (vector signed short,
- vector unsigned short);
- vector unsigned short vec_min (vector unsigned short,
- vector signed short);
- vector unsigned short vec_min (vector unsigned short,
- vector unsigned short);
- vector signed short vec_min (vector signed short, vector signed short);
- vector unsigned int vec_min (vector signed int, vector unsigned int);
- vector unsigned int vec_min (vector unsigned int, vector signed int);
- vector unsigned int vec_min (vector unsigned int, vector unsigned int);
- vector signed int vec_min (vector signed int, vector signed int);
- vector float vec_min (vector float, vector float);
-
- vector signed short vec_mladd (vector signed short, vector signed short,
- vector signed short);
- vector signed short vec_mladd (vector signed short,
- vector unsigned short,
- vector unsigned short);
- vector signed short vec_mladd (vector unsigned short,
- vector signed short,
- vector signed short);
- vector unsigned short vec_mladd (vector unsigned short,
- vector unsigned short,
- vector unsigned short);
-
- vector signed short vec_mradds (vector signed short,
- vector signed short,
- vector signed short);
-
- vector unsigned int vec_msum (vector unsigned char,
- vector unsigned char,
- vector unsigned int);
- vector signed int vec_msum (vector signed char, vector unsigned char,
- vector signed int);
- vector unsigned int vec_msum (vector unsigned short,
- vector unsigned short,
- vector unsigned int);
- vector signed int vec_msum (vector signed short, vector signed short,
- vector signed int);
-
- vector unsigned int vec_msums (vector unsigned short,
- vector unsigned short,
- vector unsigned int);
- vector signed int vec_msums (vector signed short, vector signed short,
- vector signed int);
-
- void vec_mtvscr (vector signed int);
- void vec_mtvscr (vector unsigned int);
- void vec_mtvscr (vector signed short);
- void vec_mtvscr (vector unsigned short);
- void vec_mtvscr (vector signed char);
- void vec_mtvscr (vector unsigned char);
-
- vector unsigned short vec_mule (vector unsigned char,
- vector unsigned char);
- vector signed short vec_mule (vector signed char, vector signed char);
- vector unsigned int vec_mule (vector unsigned short,
- vector unsigned short);
- vector signed int vec_mule (vector signed short, vector signed short);
-
- vector unsigned short vec_mulo (vector unsigned char,
- vector unsigned char);
- vector signed short vec_mulo (vector signed char, vector signed char);
- vector unsigned int vec_mulo (vector unsigned short,
- vector unsigned short);
- vector signed int vec_mulo (vector signed short, vector signed short);
-
- vector float vec_nmsub (vector float, vector float, vector float);
-
- vector float vec_nor (vector float, vector float);
- vector signed int vec_nor (vector signed int, vector signed int);
- vector unsigned int vec_nor (vector unsigned int, vector unsigned int);
- vector signed short vec_nor (vector signed short, vector signed short);
- vector unsigned short vec_nor (vector unsigned short,
- vector unsigned short);
- vector signed char vec_nor (vector signed char, vector signed char);
- vector unsigned char vec_nor (vector unsigned char,
- vector unsigned char);
-
- vector float vec_or (vector float, vector float);
- vector float vec_or (vector float, vector signed int);
- vector float vec_or (vector signed int, vector float);
- vector signed int vec_or (vector signed int, vector signed int);
- vector unsigned int vec_or (vector signed int, vector unsigned int);
- vector unsigned int vec_or (vector unsigned int, vector signed int);
- vector unsigned int vec_or (vector unsigned int, vector unsigned int);
- vector signed short vec_or (vector signed short, vector signed short);
- vector unsigned short vec_or (vector signed short,
- vector unsigned short);
- vector unsigned short vec_or (vector unsigned short,
- vector signed short);
- vector unsigned short vec_or (vector unsigned short,
- vector unsigned short);
- vector signed char vec_or (vector signed char, vector signed char);
- vector unsigned char vec_or (vector signed char, vector unsigned char);
- vector unsigned char vec_or (vector unsigned char, vector signed char);
- vector unsigned char vec_or (vector unsigned char,
- vector unsigned char);
-
- vector signed char vec_pack (vector signed short, vector signed short);
- vector unsigned char vec_pack (vector unsigned short,
- vector unsigned short);
- vector signed short vec_pack (vector signed int, vector signed int);
- vector unsigned short vec_pack (vector unsigned int,
- vector unsigned int);
-
- vector signed short vec_packpx (vector unsigned int,
- vector unsigned int);
-
- vector unsigned char vec_packs (vector unsigned short,
- vector unsigned short);
- vector signed char vec_packs (vector signed short, vector signed short);
-
- vector unsigned short vec_packs (vector unsigned int,
- vector unsigned int);
- vector signed short vec_packs (vector signed int, vector signed int);
-
- vector unsigned char vec_packsu (vector unsigned short,
- vector unsigned short);
- vector unsigned char vec_packsu (vector signed short,
- vector signed short);
- vector unsigned short vec_packsu (vector unsigned int,
- vector unsigned int);
- vector unsigned short vec_packsu (vector signed int, vector signed int);
-
- vector float vec_perm (vector float, vector float,
- vector unsigned char);
- vector signed int vec_perm (vector signed int, vector signed int,
- vector unsigned char);
- vector unsigned int vec_perm (vector unsigned int, vector unsigned int,
- vector unsigned char);
- vector signed short vec_perm (vector signed short, vector signed short,
- vector unsigned char);
- vector unsigned short vec_perm (vector unsigned short,
- vector unsigned short,
- vector unsigned char);
- vector signed char vec_perm (vector signed char, vector signed char,
- vector unsigned char);
- vector unsigned char vec_perm (vector unsigned char,
- vector unsigned char,
- vector unsigned char);
-
- vector float vec_re (vector float);
-
- vector signed char vec_rl (vector signed char, vector unsigned char);
- vector unsigned char vec_rl (vector unsigned char,
- vector unsigned char);
- vector signed short vec_rl (vector signed short, vector unsigned short);
-
- vector unsigned short vec_rl (vector unsigned short,
- vector unsigned short);
- vector signed int vec_rl (vector signed int, vector unsigned int);
- vector unsigned int vec_rl (vector unsigned int, vector unsigned int);
-
- vector float vec_round (vector float);
-
- vector float vec_rsqrte (vector float);
-
- vector float vec_sel (vector float, vector float, vector signed int);
- vector float vec_sel (vector float, vector float, vector unsigned int);
- vector signed int vec_sel (vector signed int, vector signed int,
- vector signed int);
- vector signed int vec_sel (vector signed int, vector signed int,
- vector unsigned int);
- vector unsigned int vec_sel (vector unsigned int, vector unsigned int,
- vector signed int);
- vector unsigned int vec_sel (vector unsigned int, vector unsigned int,
- vector unsigned int);
- vector signed short vec_sel (vector signed short, vector signed short,
- vector signed short);
- vector signed short vec_sel (vector signed short, vector signed short,
- vector unsigned short);
- vector unsigned short vec_sel (vector unsigned short,
- vector unsigned short,
- vector signed short);
- vector unsigned short vec_sel (vector unsigned short,
- vector unsigned short,
- vector unsigned short);
- vector signed char vec_sel (vector signed char, vector signed char,
- vector signed char);
- vector signed char vec_sel (vector signed char, vector signed char,
- vector unsigned char);
- vector unsigned char vec_sel (vector unsigned char,
- vector unsigned char,
- vector signed char);
- vector unsigned char vec_sel (vector unsigned char,
- vector unsigned char,
- vector unsigned char);
-
- vector signed char vec_sl (vector signed char, vector unsigned char);
- vector unsigned char vec_sl (vector unsigned char,
- vector unsigned char);
- vector signed short vec_sl (vector signed short, vector unsigned short);
-
- vector unsigned short vec_sl (vector unsigned short,
- vector unsigned short);
- vector signed int vec_sl (vector signed int, vector unsigned int);
- vector unsigned int vec_sl (vector unsigned int, vector unsigned int);
-
- vector float vec_sld (vector float, vector float, const char);
- vector signed int vec_sld (vector signed int, vector signed int,
- const char);
- vector unsigned int vec_sld (vector unsigned int, vector unsigned int,
- const char);
- vector signed short vec_sld (vector signed short, vector signed short,
- const char);
- vector unsigned short vec_sld (vector unsigned short,
- vector unsigned short, const char);
- vector signed char vec_sld (vector signed char, vector signed char,
- const char);
- vector unsigned char vec_sld (vector unsigned char,
- vector unsigned char,
- const char);
-
- vector signed int vec_sll (vector signed int, vector unsigned int);
- vector signed int vec_sll (vector signed int, vector unsigned short);
- vector signed int vec_sll (vector signed int, vector unsigned char);
- vector unsigned int vec_sll (vector unsigned int, vector unsigned int);
- vector unsigned int vec_sll (vector unsigned int,
- vector unsigned short);
- vector unsigned int vec_sll (vector unsigned int, vector unsigned char);
-
- vector signed short vec_sll (vector signed short, vector unsigned int);
- vector signed short vec_sll (vector signed short,
- vector unsigned short);
- vector signed short vec_sll (vector signed short, vector unsigned char);
-
- vector unsigned short vec_sll (vector unsigned short,
- vector unsigned int);
- vector unsigned short vec_sll (vector unsigned short,
- vector unsigned short);
- vector unsigned short vec_sll (vector unsigned short,
- vector unsigned char);
- vector signed char vec_sll (vector signed char, vector unsigned int);
- vector signed char vec_sll (vector signed char, vector unsigned short);
- vector signed char vec_sll (vector signed char, vector unsigned char);
- vector unsigned char vec_sll (vector unsigned char,
- vector unsigned int);
- vector unsigned char vec_sll (vector unsigned char,
- vector unsigned short);
- vector unsigned char vec_sll (vector unsigned char,
- vector unsigned char);
-
- vector float vec_slo (vector float, vector signed char);
- vector float vec_slo (vector float, vector unsigned char);
- vector signed int vec_slo (vector signed int, vector signed char);
- vector signed int vec_slo (vector signed int, vector unsigned char);
- vector unsigned int vec_slo (vector unsigned int, vector signed char);
- vector unsigned int vec_slo (vector unsigned int, vector unsigned char);
-
- vector signed short vec_slo (vector signed short, vector signed char);
- vector signed short vec_slo (vector signed short, vector unsigned char);
-
- vector unsigned short vec_slo (vector unsigned short,
- vector signed char);
- vector unsigned short vec_slo (vector unsigned short,
- vector unsigned char);
- vector signed char vec_slo (vector signed char, vector signed char);
- vector signed char vec_slo (vector signed char, vector unsigned char);
- vector unsigned char vec_slo (vector unsigned char, vector signed char);
-
- vector unsigned char vec_slo (vector unsigned char,
- vector unsigned char);
-
- vector signed char vec_splat (vector signed char, const char);
- vector unsigned char vec_splat (vector unsigned char, const char);
- vector signed short vec_splat (vector signed short, const char);
- vector unsigned short vec_splat (vector unsigned short, const char);
- vector float vec_splat (vector float, const char);
- vector signed int vec_splat (vector signed int, const char);
- vector unsigned int vec_splat (vector unsigned int, const char);
-
- vector signed char vec_splat_s8 (const char);
-
- vector signed short vec_splat_s16 (const char);
-
- vector signed int vec_splat_s32 (const char);
-
- vector unsigned char vec_splat_u8 (const char);
-
- vector unsigned short vec_splat_u16 (const char);
-
- vector unsigned int vec_splat_u32 (const char);
-
- vector signed char vec_sr (vector signed char, vector unsigned char);
- vector unsigned char vec_sr (vector unsigned char,
- vector unsigned char);
- vector signed short vec_sr (vector signed short, vector unsigned short);
-
- vector unsigned short vec_sr (vector unsigned short,
- vector unsigned short);
- vector signed int vec_sr (vector signed int, vector unsigned int);
- vector unsigned int vec_sr (vector unsigned int, vector unsigned int);
-
- vector signed char vec_sra (vector signed char, vector unsigned char);
- vector unsigned char vec_sra (vector unsigned char,
- vector unsigned char);
- vector signed short vec_sra (vector signed short,
- vector unsigned short);
- vector unsigned short vec_sra (vector unsigned short,
- vector unsigned short);
- vector signed int vec_sra (vector signed int, vector unsigned int);
- vector unsigned int vec_sra (vector unsigned int, vector unsigned int);
-
- vector signed int vec_srl (vector signed int, vector unsigned int);
- vector signed int vec_srl (vector signed int, vector unsigned short);
- vector signed int vec_srl (vector signed int, vector unsigned char);
- vector unsigned int vec_srl (vector unsigned int, vector unsigned int);
- vector unsigned int vec_srl (vector unsigned int,
- vector unsigned short);
- vector unsigned int vec_srl (vector unsigned int, vector unsigned char);
-
- vector signed short vec_srl (vector signed short, vector unsigned int);
- vector signed short vec_srl (vector signed short,
- vector unsigned short);
- vector signed short vec_srl (vector signed short, vector unsigned char);
-
- vector unsigned short vec_srl (vector unsigned short,
- vector unsigned int);
- vector unsigned short vec_srl (vector unsigned short,
- vector unsigned short);
- vector unsigned short vec_srl (vector unsigned short,
- vector unsigned char);
- vector signed char vec_srl (vector signed char, vector unsigned int);
- vector signed char vec_srl (vector signed char, vector unsigned short);
- vector signed char vec_srl (vector signed char, vector unsigned char);
- vector unsigned char vec_srl (vector unsigned char,
- vector unsigned int);
- vector unsigned char vec_srl (vector unsigned char,
- vector unsigned short);
- vector unsigned char vec_srl (vector unsigned char,
- vector unsigned char);
-
- vector float vec_sro (vector float, vector signed char);
- vector float vec_sro (vector float, vector unsigned char);
- vector signed int vec_sro (vector signed int, vector signed char);
- vector signed int vec_sro (vector signed int, vector unsigned char);
- vector unsigned int vec_sro (vector unsigned int, vector signed char);
- vector unsigned int vec_sro (vector unsigned int, vector unsigned char);
-
- vector signed short vec_sro (vector signed short, vector signed char);
- vector signed short vec_sro (vector signed short, vector unsigned char);
-
- vector unsigned short vec_sro (vector unsigned short,
- vector signed char);
- vector unsigned short vec_sro (vector unsigned short,
- vector unsigned char);
- vector signed char vec_sro (vector signed char, vector signed char);
- vector signed char vec_sro (vector signed char, vector unsigned char);
- vector unsigned char vec_sro (vector unsigned char, vector signed char);
-
- vector unsigned char vec_sro (vector unsigned char,
- vector unsigned char);
-
- void vec_st (vector float, int, float *);
- void vec_st (vector float, int, vector float *);
- void vec_st (vector signed int, int, int *);
- void vec_st (vector signed int, int, unsigned int *);
- void vec_st (vector unsigned int, int, unsigned int *);
- void vec_st (vector unsigned int, int, vector unsigned int *);
- void vec_st (vector signed short, int, short *);
- void vec_st (vector signed short, int, vector unsigned short *);
- void vec_st (vector signed short, int, vector signed short *);
- void vec_st (vector unsigned short, int, unsigned short *);
- void vec_st (vector unsigned short, int, vector unsigned short *);
- void vec_st (vector signed char, int, signed char *);
- void vec_st (vector signed char, int, unsigned char *);
- void vec_st (vector signed char, int, vector signed char *);
- void vec_st (vector unsigned char, int, unsigned char *);
- void vec_st (vector unsigned char, int, vector unsigned char *);
-
- void vec_ste (vector signed char, int, unsigned char *);
- void vec_ste (vector signed char, int, signed char *);
- void vec_ste (vector unsigned char, int, unsigned char *);
- void vec_ste (vector signed short, int, short *);
- void vec_ste (vector signed short, int, unsigned short *);
- void vec_ste (vector unsigned short, int, void *);
- void vec_ste (vector signed int, int, unsigned int *);
- void vec_ste (vector signed int, int, int *);
- void vec_ste (vector unsigned int, int, unsigned int *);
- void vec_ste (vector float, int, float *);
-
- void vec_stl (vector float, int, vector float *);
- void vec_stl (vector float, int, float *);
- void vec_stl (vector signed int, int, vector signed int *);
- void vec_stl (vector signed int, int, int *);
- void vec_stl (vector signed int, int, unsigned int *);
- void vec_stl (vector unsigned int, int, vector unsigned int *);
- void vec_stl (vector unsigned int, int, unsigned int *);
- void vec_stl (vector signed short, int, short *);
- void vec_stl (vector signed short, int, unsigned short *);
- void vec_stl (vector signed short, int, vector signed short *);
- void vec_stl (vector unsigned short, int, unsigned short *);
- void vec_stl (vector unsigned short, int, vector signed short *);
- void vec_stl (vector signed char, int, signed char *);
- void vec_stl (vector signed char, int, unsigned char *);
- void vec_stl (vector signed char, int, vector signed char *);
- void vec_stl (vector unsigned char, int, unsigned char *);
- void vec_stl (vector unsigned char, int, vector unsigned char *);
-
- vector signed char vec_sub (vector signed char, vector signed char);
- vector unsigned char vec_sub (vector signed char, vector unsigned char);
-
- vector unsigned char vec_sub (vector unsigned char, vector signed char);
-
- vector unsigned char vec_sub (vector unsigned char,
- vector unsigned char);
- vector signed short vec_sub (vector signed short, vector signed short);
- vector unsigned short vec_sub (vector signed short,
- vector unsigned short);
- vector unsigned short vec_sub (vector unsigned short,
- vector signed short);
- vector unsigned short vec_sub (vector unsigned short,
- vector unsigned short);
- vector signed int vec_sub (vector signed int, vector signed int);
- vector unsigned int vec_sub (vector signed int, vector unsigned int);
- vector unsigned int vec_sub (vector unsigned int, vector signed int);
- vector unsigned int vec_sub (vector unsigned int, vector unsigned int);
- vector float vec_sub (vector float, vector float);
-
- vector unsigned int vec_subc (vector unsigned int, vector unsigned int);
-
- vector unsigned char vec_subs (vector signed char,
- vector unsigned char);
- vector unsigned char vec_subs (vector unsigned char,
- vector signed char);
- vector unsigned char vec_subs (vector unsigned char,
- vector unsigned char);
- vector signed char vec_subs (vector signed char, vector signed char);
- vector unsigned short vec_subs (vector signed short,
- vector unsigned short);
- vector unsigned short vec_subs (vector unsigned short,
- vector signed short);
- vector unsigned short vec_subs (vector unsigned short,
- vector unsigned short);
- vector signed short vec_subs (vector signed short, vector signed short);
-
- vector unsigned int vec_subs (vector signed int, vector unsigned int);
- vector unsigned int vec_subs (vector unsigned int, vector signed int);
- vector unsigned int vec_subs (vector unsigned int, vector unsigned int);
-
- vector signed int vec_subs (vector signed int, vector signed int);
-
- vector unsigned int vec_sum4s (vector unsigned char,
- vector unsigned int);
- vector signed int vec_sum4s (vector signed char, vector signed int);
- vector signed int vec_sum4s (vector signed short, vector signed int);
-
- vector signed int vec_sum2s (vector signed int, vector signed int);
-
- vector signed int vec_sums (vector signed int, vector signed int);
-
- vector float vec_trunc (vector float);
-
- vector signed short vec_unpackh (vector signed char);
- vector unsigned int vec_unpackh (vector signed short);
- vector signed int vec_unpackh (vector signed short);
-
- vector signed short vec_unpackl (vector signed char);
- vector unsigned int vec_unpackl (vector signed short);
- vector signed int vec_unpackl (vector signed short);
-
- vector float vec_xor (vector float, vector float);
- vector float vec_xor (vector float, vector signed int);
- vector float vec_xor (vector signed int, vector float);
- vector signed int vec_xor (vector signed int, vector signed int);
- vector unsigned int vec_xor (vector signed int, vector unsigned int);
- vector unsigned int vec_xor (vector unsigned int, vector signed int);
- vector unsigned int vec_xor (vector unsigned int, vector unsigned int);
- vector signed short vec_xor (vector signed short, vector signed short);
- vector unsigned short vec_xor (vector signed short,
- vector unsigned short);
- vector unsigned short vec_xor (vector unsigned short,
- vector signed short);
- vector unsigned short vec_xor (vector unsigned short,
- vector unsigned short);
- vector signed char vec_xor (vector signed char, vector signed char);
- vector unsigned char vec_xor (vector signed char, vector unsigned char);
-
- vector unsigned char vec_xor (vector unsigned char, vector signed char);
-
- vector unsigned char vec_xor (vector unsigned char,
- vector unsigned char);
-
- vector signed int vec_all_eq (vector signed char, vector unsigned char);
-
- vector signed int vec_all_eq (vector signed char, vector signed char);
- vector signed int vec_all_eq (vector unsigned char, vector signed char);
-
- vector signed int vec_all_eq (vector unsigned char,
- vector unsigned char);
- vector signed int vec_all_eq (vector signed short,
- vector unsigned short);
- vector signed int vec_all_eq (vector signed short, vector signed short);
-
- vector signed int vec_all_eq (vector unsigned short,
- vector signed short);
- vector signed int vec_all_eq (vector unsigned short,
- vector unsigned short);
- vector signed int vec_all_eq (vector signed int, vector unsigned int);
- vector signed int vec_all_eq (vector signed int, vector signed int);
- vector signed int vec_all_eq (vector unsigned int, vector signed int);
- vector signed int vec_all_eq (vector unsigned int, vector unsigned int);
-
- vector signed int vec_all_eq (vector float, vector float);
-
- vector signed int vec_all_ge (vector signed char, vector unsigned char);
-
- vector signed int vec_all_ge (vector unsigned char, vector signed char);
-
- vector signed int vec_all_ge (vector unsigned char,
- vector unsigned char);
- vector signed int vec_all_ge (vector signed char, vector signed char);
- vector signed int vec_all_ge (vector signed short,
- vector unsigned short);
- vector signed int vec_all_ge (vector unsigned short,
- vector signed short);
- vector signed int vec_all_ge (vector unsigned short,
- vector unsigned short);
- vector signed int vec_all_ge (vector signed short, vector signed short);
-
- vector signed int vec_all_ge (vector signed int, vector unsigned int);
- vector signed int vec_all_ge (vector unsigned int, vector signed int);
- vector signed int vec_all_ge (vector unsigned int, vector unsigned int);
-
- vector signed int vec_all_ge (vector signed int, vector signed int);
- vector signed int vec_all_ge (vector float, vector float);
-
- vector signed int vec_all_gt (vector signed char, vector unsigned char);
-
- vector signed int vec_all_gt (vector unsigned char, vector signed char);
-
- vector signed int vec_all_gt (vector unsigned char,
- vector unsigned char);
- vector signed int vec_all_gt (vector signed char, vector signed char);
- vector signed int vec_all_gt (vector signed short,
- vector unsigned short);
- vector signed int vec_all_gt (vector unsigned short,
- vector signed short);
- vector signed int vec_all_gt (vector unsigned short,
- vector unsigned short);
- vector signed int vec_all_gt (vector signed short, vector signed short);
-
- vector signed int vec_all_gt (vector signed int, vector unsigned int);
- vector signed int vec_all_gt (vector unsigned int, vector signed int);
- vector signed int vec_all_gt (vector unsigned int, vector unsigned int);
-
- vector signed int vec_all_gt (vector signed int, vector signed int);
- vector signed int vec_all_gt (vector float, vector float);
-
- vector signed int vec_all_in (vector float, vector float);
-
- vector signed int vec_all_le (vector signed char, vector unsigned char);
-
- vector signed int vec_all_le (vector unsigned char, vector signed char);
-
- vector signed int vec_all_le (vector unsigned char,
- vector unsigned char);
- vector signed int vec_all_le (vector signed char, vector signed char);
- vector signed int vec_all_le (vector signed short,
- vector unsigned short);
- vector signed int vec_all_le (vector unsigned short,
- vector signed short);
- vector signed int vec_all_le (vector unsigned short,
- vector unsigned short);
- vector signed int vec_all_le (vector signed short, vector signed short);
-
- vector signed int vec_all_le (vector signed int, vector unsigned int);
- vector signed int vec_all_le (vector unsigned int, vector signed int);
- vector signed int vec_all_le (vector unsigned int, vector unsigned int);
-
- vector signed int vec_all_le (vector signed int, vector signed int);
- vector signed int vec_all_le (vector float, vector float);
-
- vector signed int vec_all_lt (vector signed char, vector unsigned char);
-
- vector signed int vec_all_lt (vector unsigned char, vector signed char);
-
- vector signed int vec_all_lt (vector unsigned char,
- vector unsigned char);
- vector signed int vec_all_lt (vector signed char, vector signed char);
- vector signed int vec_all_lt (vector signed short,
- vector unsigned short);
- vector signed int vec_all_lt (vector unsigned short,
- vector signed short);
- vector signed int vec_all_lt (vector unsigned short,
- vector unsigned short);
- vector signed int vec_all_lt (vector signed short, vector signed short);
-
- vector signed int vec_all_lt (vector signed int, vector unsigned int);
- vector signed int vec_all_lt (vector unsigned int, vector signed int);
- vector signed int vec_all_lt (vector unsigned int, vector unsigned int);
-
- vector signed int vec_all_lt (vector signed int, vector signed int);
- vector signed int vec_all_lt (vector float, vector float);
-
- vector signed int vec_all_nan (vector float);
-
- vector signed int vec_all_ne (vector signed char, vector unsigned char);
-
- vector signed int vec_all_ne (vector signed char, vector signed char);
- vector signed int vec_all_ne (vector unsigned char, vector signed char);
-
- vector signed int vec_all_ne (vector unsigned char,
- vector unsigned char);
- vector signed int vec_all_ne (vector signed short,
- vector unsigned short);
- vector signed int vec_all_ne (vector signed short, vector signed short);
-
- vector signed int vec_all_ne (vector unsigned short,
- vector signed short);
- vector signed int vec_all_ne (vector unsigned short,
- vector unsigned short);
- vector signed int vec_all_ne (vector signed int, vector unsigned int);
- vector signed int vec_all_ne (vector signed int, vector signed int);
- vector signed int vec_all_ne (vector unsigned int, vector signed int);
- vector signed int vec_all_ne (vector unsigned int, vector unsigned int);
-
- vector signed int vec_all_ne (vector float, vector float);
-
- vector signed int vec_all_nge (vector float, vector float);
-
- vector signed int vec_all_ngt (vector float, vector float);
-
- vector signed int vec_all_nle (vector float, vector float);
-
- vector signed int vec_all_nlt (vector float, vector float);
-
- vector signed int vec_all_numeric (vector float);
-
- vector signed int vec_any_eq (vector signed char, vector unsigned char);
-
- vector signed int vec_any_eq (vector signed char, vector signed char);
- vector signed int vec_any_eq (vector unsigned char, vector signed char);
-
- vector signed int vec_any_eq (vector unsigned char,
- vector unsigned char);
- vector signed int vec_any_eq (vector signed short,
- vector unsigned short);
- vector signed int vec_any_eq (vector signed short, vector signed short);
-
- vector signed int vec_any_eq (vector unsigned short,
- vector signed short);
- vector signed int vec_any_eq (vector unsigned short,
- vector unsigned short);
- vector signed int vec_any_eq (vector signed int, vector unsigned int);
- vector signed int vec_any_eq (vector signed int, vector signed int);
- vector signed int vec_any_eq (vector unsigned int, vector signed int);
- vector signed int vec_any_eq (vector unsigned int, vector unsigned int);
-
- vector signed int vec_any_eq (vector float, vector float);
-
- vector signed int vec_any_ge (vector signed char, vector unsigned char);
-
- vector signed int vec_any_ge (vector unsigned char, vector signed char);
-
- vector signed int vec_any_ge (vector unsigned char,
- vector unsigned char);
- vector signed int vec_any_ge (vector signed char, vector signed char);
- vector signed int vec_any_ge (vector signed short,
- vector unsigned short);
- vector signed int vec_any_ge (vector unsigned short,
- vector signed short);
- vector signed int vec_any_ge (vector unsigned short,
- vector unsigned short);
- vector signed int vec_any_ge (vector signed short, vector signed short);
-
- vector signed int vec_any_ge (vector signed int, vector unsigned int);
- vector signed int vec_any_ge (vector unsigned int, vector signed int);
- vector signed int vec_any_ge (vector unsigned int, vector unsigned int);
-
- vector signed int vec_any_ge (vector signed int, vector signed int);
- vector signed int vec_any_ge (vector float, vector float);
-
- vector signed int vec_any_gt (vector signed char, vector unsigned char);
-
- vector signed int vec_any_gt (vector unsigned char, vector signed char);
-
- vector signed int vec_any_gt (vector unsigned char,
- vector unsigned char);
- vector signed int vec_any_gt (vector signed char, vector signed char);
- vector signed int vec_any_gt (vector signed short,
- vector unsigned short);
- vector signed int vec_any_gt (vector unsigned short,
- vector signed short);
- vector signed int vec_any_gt (vector unsigned short,
- vector unsigned short);
- vector signed int vec_any_gt (vector signed short, vector signed short);
-
- vector signed int vec_any_gt (vector signed int, vector unsigned int);
- vector signed int vec_any_gt (vector unsigned int, vector signed int);
- vector signed int vec_any_gt (vector unsigned int, vector unsigned int);
-
- vector signed int vec_any_gt (vector signed int, vector signed int);
- vector signed int vec_any_gt (vector float, vector float);
-
- vector signed int vec_any_le (vector signed char, vector unsigned char);
-
- vector signed int vec_any_le (vector unsigned char, vector signed char);
-
- vector signed int vec_any_le (vector unsigned char,
- vector unsigned char);
- vector signed int vec_any_le (vector signed char, vector signed char);
- vector signed int vec_any_le (vector signed short,
- vector unsigned short);
- vector signed int vec_any_le (vector unsigned short,
- vector signed short);
- vector signed int vec_any_le (vector unsigned short,
- vector unsigned short);
- vector signed int vec_any_le (vector signed short, vector signed short);
-
- vector signed int vec_any_le (vector signed int, vector unsigned int);
- vector signed int vec_any_le (vector unsigned int, vector signed int);
- vector signed int vec_any_le (vector unsigned int, vector unsigned int);
-
- vector signed int vec_any_le (vector signed int, vector signed int);
- vector signed int vec_any_le (vector float, vector float);
-
- vector signed int vec_any_lt (vector signed char, vector unsigned char);
-
- vector signed int vec_any_lt (vector unsigned char, vector signed char);
-
- vector signed int vec_any_lt (vector unsigned char,
- vector unsigned char);
- vector signed int vec_any_lt (vector signed char, vector signed char);
- vector signed int vec_any_lt (vector signed short,
- vector unsigned short);
- vector signed int vec_any_lt (vector unsigned short,
- vector signed short);
- vector signed int vec_any_lt (vector unsigned short,
- vector unsigned short);
- vector signed int vec_any_lt (vector signed short, vector signed short);
-
- vector signed int vec_any_lt (vector signed int, vector unsigned int);
- vector signed int vec_any_lt (vector unsigned int, vector signed int);
- vector signed int vec_any_lt (vector unsigned int, vector unsigned int);
-
- vector signed int vec_any_lt (vector signed int, vector signed int);
- vector signed int vec_any_lt (vector float, vector float);
-
- vector signed int vec_any_nan (vector float);
-
- vector signed int vec_any_ne (vector signed char, vector unsigned char);
-
- vector signed int vec_any_ne (vector signed char, vector signed char);
- vector signed int vec_any_ne (vector unsigned char, vector signed char);
-
- vector signed int vec_any_ne (vector unsigned char,
- vector unsigned char);
- vector signed int vec_any_ne (vector signed short,
- vector unsigned short);
- vector signed int vec_any_ne (vector signed short, vector signed short);
-
- vector signed int vec_any_ne (vector unsigned short,
- vector signed short);
- vector signed int vec_any_ne (vector unsigned short,
- vector unsigned short);
- vector signed int vec_any_ne (vector signed int, vector unsigned int);
- vector signed int vec_any_ne (vector signed int, vector signed int);
- vector signed int vec_any_ne (vector unsigned int, vector signed int);
- vector signed int vec_any_ne (vector unsigned int, vector unsigned int);
-
- vector signed int vec_any_ne (vector float, vector float);
-
- vector signed int vec_any_nge (vector float, vector float);
-
- vector signed int vec_any_ngt (vector float, vector float);
-
- vector signed int vec_any_nle (vector float, vector float);
-
- vector signed int vec_any_nlt (vector float, vector float);
-
- vector signed int vec_any_numeric (vector float);
-
- vector signed int vec_any_out (vector float, vector float);
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Pragmas, Next: Unnamed Fields, Prev: Target Builtins, Up: C Extensions
-
-Pragmas Accepted by GCC
-=======================
-
- GCC supports several types of pragmas, primarily in order to compile
-code originally written for other compilers. Note that in general we
-do not recommend the use of pragmas; *Note Function Attributes::, for
-further explanation.
-
-* Menu:
-
-* ARM Pragmas::
-* Darwin Pragmas::
-* Solaris Pragmas::
-* Tru64 Pragmas::
-
-\1f
-File: gcc.info, Node: ARM Pragmas, Next: Darwin Pragmas, Up: Pragmas
-
-ARM Pragmas
------------
-
- The ARM target defines pragmas for controlling the default addition
-of `long_call' and `short_call' attributes to functions. *Note
-Function Attributes::, for information about the effects of these
-attributes.
-
-`long_calls'
- Set all subsequent functions to have the `long_call' attribute.
-
-`no_long_calls'
- Set all subsequent functions to have the `short_call' attribute.
-
-`long_calls_off'
- Do not affect the `long_call' or `short_call' attributes of
- subsequent functions.
-
-\1f
-File: gcc.info, Node: Darwin Pragmas, Next: Solaris Pragmas, Prev: ARM Pragmas, Up: Pragmas
-
-Darwin Pragmas
---------------
-
- The following pragmas are available for all architectures running the
-Darwin operating system. These are useful for compatibility with other
-MacOS compilers.
-
-`mark TOKENS...'
- This pragma is accepted, but has no effect.
-
-`options align=ALIGNMENT'
- This pragma sets the alignment of fields in structures. The
- values of ALIGNMENT may be `mac68k', to emulate m68k alignment, or
- `power', to emulate PowerPC alignment. Uses of this pragma nest
- properly; to restore the previous setting, use `reset' for the
- ALIGNMENT.
-
-`segment TOKENS...'
- This pragma is accepted, but has no effect.
-
-`unused (VAR [, VAR]...)'
- This pragma declares variables to be possibly unused. GCC will not
- produce warnings for the listed variables. The effect is similar
- to that of the `unused' attribute, except that this pragma may
- appear anywhere within the variables' scopes.
-
-\1f
-File: gcc.info, Node: Solaris Pragmas, Next: Tru64 Pragmas, Prev: Darwin Pragmas, Up: Pragmas
-
-Solaris Pragmas
----------------
-
- For compatibility with the SunPRO compiler, the following pragma is
-supported.
-
-`redefine_extname OLDNAME NEWNAME'
- This pragma gives the C function OLDNAME the assembler label
- NEWNAME. The pragma must appear before the function declaration.
- This pragma is equivalent to the asm labels extension (*note Asm
- Labels::). The preprocessor defines `__PRAGMA_REDEFINE_EXTNAME'
- if the pragma is available.
-
-\1f
-File: gcc.info, Node: Tru64 Pragmas, Prev: Solaris Pragmas, Up: Pragmas
-
-Tru64 Pragmas
--------------
-
- For compatibility with the Compaq C compiler, the following pragma
-is supported.
-
-`extern_prefix STRING'
- This pragma renames all subsequent function and variable
- declarations such that STRING is prepended to the name. This
- effect may be terminated by using another `extern_prefix' pragma
- with the empty string.
-
- This pragma is similar in intent to to the asm labels extension
- (*note Asm Labels::) in that the system programmer wants to change
- the assembly-level ABI without changing the source-level API. The
- preprocessor defines `__PRAGMA_EXTERN_PREFIX' if the pragma is
- available.
-
-\1f
-File: gcc.info, Node: Unnamed Fields, Prev: Pragmas, Up: C Extensions
-
-Unnamed struct/union fields within structs/unions.
-==================================================
-
- For compatibility with other compilers, GCC allows you to define a
-structure or union that contains, as fields, structures and unions
-without names. For example:
-
- struct {
- int a;
- union {
- int b;
- float c;
- };
- int d;
- } foo;
-
- In this example, the user would be able to access members of the
-unnamed union with code like `foo.b'. Note that only unnamed structs
-and unions are allowed, you may not have, for example, an unnamed `int'.
-
- You must never create such structures that cause ambiguous field
-definitions. For example, this structure:
-
- struct {
- int a;
- struct {
- int a;
- };
- } foo;
-
- It is ambiguous which `a' is being referred to with `foo.a'. Such
-constructs are not supported and must be avoided. In the future, such
-constructs may be detected and treated as compilation errors.
-
-\1f
-File: gcc.info, Node: C++ Extensions, Next: Objective-C, Prev: C Extensions, Up: Top
-
-Extensions to the C++ Language
-******************************
-
- The GNU compiler provides these extensions to the C++ language (and
-you can also use most of the C language extensions in your C++
-programs). If you want to write code that checks whether these
-features are available, you can test for the GNU compiler the same way
-as for C programs: check for a predefined macro `__GNUC__'. You can
-also use `__GNUG__' to test specifically for GNU C++ (*note Standard
-Predefined Macros: (cpp.info)Standard Predefined.).
-
-* Menu:
-
-* Min and Max:: C++ Minimum and maximum operators.
-* Volatiles:: What constitutes an access to a volatile object.
-* Restricted Pointers:: C99 restricted pointers and references.
-* Vague Linkage:: Where G++ puts inlines, vtables and such.
-* C++ Interface:: You can use a single C++ header file for both
- declarations and definitions.
-* Template Instantiation:: Methods for ensuring that exactly one copy of
- each needed template instantiation is emitted.
-* Bound member functions:: You can extract a function pointer to the
- method denoted by a `->*' or `.*' expression.
-* C++ Attributes:: Variable, function, and type attributes for C++ only.
-* Java Exceptions:: Tweaking exception handling to work with Java.
-* Deprecated Features:: Things might disappear from g++.
-* Backwards Compatibility:: Compatibilities with earlier definitions of C++.
-
-\1f
-File: gcc.info, Node: Min and Max, Next: Volatiles, Up: C++ Extensions
-
-Minimum and Maximum Operators in C++
-====================================
-
- It is very convenient to have operators which return the "minimum"
-or the "maximum" of two arguments. In GNU C++ (but not in GNU C),
-
-`A <? B'
- is the "minimum", returning the smaller of the numeric values A
- and B;
-
-`A >? B'
- is the "maximum", returning the larger of the numeric values A and
- B.
-
- These operations are not primitive in ordinary C++, since you can
-use a macro to return the minimum of two things in C++, as in the
-following example.
-
- #define MIN(X,Y) ((X) < (Y) ? : (X) : (Y))
-
-You might then use `int min = MIN (i, j);' to set MIN to the minimum
-value of variables I and J.
-
- However, side effects in `X' or `Y' may cause unintended behavior.
-For example, `MIN (i++, j++)' will fail, incrementing the smaller
-counter twice. The GNU C `typeof' extension allows you to write safe
-macros that avoid this kind of problem (*note Typeof::). However,
-writing `MIN' and `MAX' as macros also forces you to use function-call
-notation for a fundamental arithmetic operation. Using GNU C++
-extensions, you can write `int min = i <? j;' instead.
-
- Since `<?' and `>?' are built into the compiler, they properly
-handle expressions with side-effects; `int min = i++ <? j++;' works
-correctly.
-
-\1f
-File: gcc.info, Node: Volatiles, Next: Restricted Pointers, Prev: Min and Max, Up: C++ Extensions
-
-When is a Volatile Object Accessed?
-===================================
-
- Both the C and C++ standard have the concept of volatile objects.
-These are normally accessed by pointers and used for accessing
-hardware. The standards encourage compilers to refrain from
-optimizations concerning accesses to volatile objects that it might
-perform on non-volatile objects. The C standard leaves it
-implementation defined as to what constitutes a volatile access. The
-C++ standard omits to specify this, except to say that C++ should
-behave in a similar manner to C with respect to volatiles, where
-possible. The minimum either standard specifies is that at a sequence
-point all previous accesses to volatile objects have stabilized and no
-subsequent accesses have occurred. Thus an implementation is free to
-reorder and combine volatile accesses which occur between sequence
-points, but cannot do so for accesses across a sequence point. The use
-of volatiles does not allow you to violate the restriction on updating
-objects multiple times within a sequence point.
-
- In most expressions, it is intuitively obvious what is a read and
-what is a write. For instance
-
- volatile int *dst = SOMEVALUE;
- volatile int *src = SOMEOTHERVALUE;
- *dst = *src;
-
-will cause a read of the volatile object pointed to by SRC and stores
-the value into the volatile object pointed to by DST. There is no
-guarantee that these reads and writes are atomic, especially for objects
-larger than `int'.
-
- Less obvious expressions are where something which looks like an
-access is used in a void context. An example would be,
-
- volatile int *src = SOMEVALUE;
- *src;
-
- With C, such expressions are rvalues, and as rvalues cause a read of
-the object, GCC interprets this as a read of the volatile being pointed
-to. The C++ standard specifies that such expressions do not undergo
-lvalue to rvalue conversion, and that the type of the dereferenced
-object may be incomplete. The C++ standard does not specify explicitly
-that it is this lvalue to rvalue conversion which is responsible for
-causing an access. However, there is reason to believe that it is,
-because otherwise certain simple expressions become undefined. However,
-because it would surprise most programmers, G++ treats dereferencing a
-pointer to volatile object of complete type in a void context as a read
-of the object. When the object has incomplete type, G++ issues a
-warning.
-
- struct S;
- struct T {int m;};
- volatile S *ptr1 = SOMEVALUE;
- volatile T *ptr2 = SOMEVALUE;
- *ptr1;
- *ptr2;
-
- In this example, a warning is issued for `*ptr1', and `*ptr2' causes
-a read of the object pointed to. If you wish to force an error on the
-first case, you must force a conversion to rvalue with, for instance a
-static cast, `static_cast<S>(*ptr1)'.
-
- When using a reference to volatile, G++ does not treat equivalent
-expressions as accesses to volatiles, but instead issues a warning that
-no volatile is accessed. The rationale for this is that otherwise it
-becomes difficult to determine where volatile access occur, and not
-possible to ignore the return value from functions returning volatile
-references. Again, if you wish to force a read, cast the reference to
-an rvalue.
-
-\1f
-File: gcc.info, Node: Restricted Pointers, Next: Vague Linkage, Prev: Volatiles, Up: C++ Extensions
-
-Restricting Pointer Aliasing
-============================
-
- As with gcc, g++ understands the C99 feature of restricted pointers,
-specified with the `__restrict__', or `__restrict' type qualifier.
-Because you cannot compile C++ by specifying the `-std=c99' language
-flag, `restrict' is not a keyword in C++.
-
- In addition to allowing restricted pointers, you can specify
-restricted references, which indicate that the reference is not aliased
-in the local context.
-
- void fn (int *__restrict__ rptr, int &__restrict__ rref)
- {
- ...
- }
-
-In the body of `fn', RPTR points to an unaliased integer and RREF
-refers to a (different) unaliased integer.
-
- You may also specify whether a member function's THIS pointer is
-unaliased by using `__restrict__' as a member function qualifier.
-
- void T::fn () __restrict__
- {
- ...
- }
-
-Within the body of `T::fn', THIS will have the effective definition `T
-*__restrict__ const this'. Notice that the interpretation of a
-`__restrict__' member function qualifier is different to that of
-`const' or `volatile' qualifier, in that it is applied to the pointer
-rather than the object. This is consistent with other compilers which
-implement restricted pointers.
-
- As with all outermost parameter qualifiers, `__restrict__' is
-ignored in function definition matching. This means you only need to
-specify `__restrict__' in a function definition, rather than in a
-function prototype as well.
-
-\1f
-File: gcc.info, Node: Vague Linkage, Next: C++ Interface, Prev: Restricted Pointers, Up: C++ Extensions
-
-Vague Linkage
-=============
-
- There are several constructs in C++ which require space in the object
-file but are not clearly tied to a single translation unit. We say that
-these constructs have "vague linkage". Typically such constructs are
-emitted wherever they are needed, though sometimes we can be more
-clever.
-
-Inline Functions
- Inline functions are typically defined in a header file which can
- be included in many different compilations. Hopefully they can
- usually be inlined, but sometimes an out-of-line copy is
- necessary, if the address of the function is taken or if inlining
- fails. In general, we emit an out-of-line copy in all translation
- units where one is needed. As an exception, we only emit inline
- virtual functions with the vtable, since it will always require a
- copy.
-
- Local static variables and string constants used in an inline
- function are also considered to have vague linkage, since they
- must be shared between all inlined and out-of-line instances of
- the function.
-
-VTables
- C++ virtual functions are implemented in most compilers using a
- lookup table, known as a vtable. The vtable contains pointers to
- the virtual functions provided by a class, and each object of the
- class contains a pointer to its vtable (or vtables, in some
- multiple-inheritance situations). If the class declares any
- non-inline, non-pure virtual functions, the first one is chosen as
- the "key method" for the class, and the vtable is only emitted in
- the translation unit where the key method is defined.
-
- _Note:_ If the chosen key method is later defined as inline, the
- vtable will still be emitted in every translation unit which
- defines it. Make sure that any inline virtuals are declared
- inline in the class body, even if they are not defined there.
-
-type_info objects
- C++ requires information about types to be written out in order to
- implement `dynamic_cast', `typeid' and exception handling. For
- polymorphic classes (classes with virtual functions), the type_info
- object is written out along with the vtable so that `dynamic_cast'
- can determine the dynamic type of a class object at runtime. For
- all other types, we write out the type_info object when it is
- used: when applying `typeid' to an expression, throwing an object,
- or referring to a type in a catch clause or exception
- specification.
-
-Template Instantiations
- Most everything in this section also applies to template
- instantiations, but there are other options as well. *Note
- Where's the Template?: Template Instantiation.
-
-
- When used with GNU ld version 2.8 or later on an ELF system such as
-Linux/GNU or Solaris 2, or on Microsoft Windows, duplicate copies of
-these constructs will be discarded at link time. This is known as
-COMDAT support.
-
- On targets that don't support COMDAT, but do support weak symbols,
-GCC will use them. This way one copy will override all the others, but
-the unused copies will still take up space in the executable.
-
- For targets which do not support either COMDAT or weak symbols, most
-entities with vague linkage will be emitted as local symbols to avoid
-duplicate definition errors from the linker. This will not happen for
-local statics in inlines, however, as having multiple copies will
-almost certainly break things.
-
- *Note Declarations and Definitions in One Header: C++ Interface, for
-another way to control placement of these constructs.
-
-\1f
-File: gcc.info, Node: C++ Interface, Next: Template Instantiation, Prev: Vague Linkage, Up: C++ Extensions
-
-Declarations and Definitions in One Header
-==========================================
-
- C++ object definitions can be quite complex. In principle, your
-source code will need two kinds of things for each object that you use
-across more than one source file. First, you need an "interface"
-specification, describing its structure with type declarations and
-function prototypes. Second, you need the "implementation" itself. It
-can be tedious to maintain a separate interface description in a header
-file, in parallel to the actual implementation. It is also dangerous,
-since separate interface and implementation definitions may not remain
-parallel.
-
- With GNU C++, you can use a single header file for both purposes.
-
- _Warning:_ The mechanism to specify this is in transition. For the
- nonce, you must use one of two `#pragma' commands; in a future
- release of GNU C++, an alternative mechanism will make these
- `#pragma' commands unnecessary.
-
- The header file contains the full definitions, but is marked with
-`#pragma interface' in the source code. This allows the compiler to
-use the header file only as an interface specification when ordinary
-source files incorporate it with `#include'. In the single source file
-where the full implementation belongs, you can use either a naming
-convention or `#pragma implementation' to indicate this alternate use
-of the header file.
-
-`#pragma interface'
-`#pragma interface "SUBDIR/OBJECTS.h"'
- Use this directive in _header files_ that define object classes,
- to save space in most of the object files that use those classes.
- Normally, local copies of certain information (backup copies of
- inline member functions, debugging information, and the internal
- tables that implement virtual functions) must be kept in each
- object file that includes class definitions. You can use this
- pragma to avoid such duplication. When a header file containing
- `#pragma interface' is included in a compilation, this auxiliary
- information will not be generated (unless the main input source
- file itself uses `#pragma implementation'). Instead, the object
- files will contain references to be resolved at link time.
-
- The second form of this directive is useful for the case where you
- have multiple headers with the same name in different directories.
- If you use this form, you must specify the same string to `#pragma
- implementation'.
-
-`#pragma implementation'
-`#pragma implementation "OBJECTS.h"'
- Use this pragma in a _main input file_, when you want full output
- from included header files to be generated (and made globally
- visible). The included header file, in turn, should use `#pragma
- interface'. Backup copies of inline member functions, debugging
- information, and the internal tables used to implement virtual
- functions are all generated in implementation files.
-
- If you use `#pragma implementation' with no argument, it applies to
- an include file with the same basename(1) as your source file.
- For example, in `allclass.cc', giving just `#pragma implementation'
- by itself is equivalent to `#pragma implementation "allclass.h"'.
-
- In versions of GNU C++ prior to 2.6.0 `allclass.h' was treated as
- an implementation file whenever you would include it from
- `allclass.cc' even if you never specified `#pragma
- implementation'. This was deemed to be more trouble than it was
- worth, however, and disabled.
-
- If you use an explicit `#pragma implementation', it must appear in
- your source file _before_ you include the affected header files.
-
- Use the string argument if you want a single implementation file to
- include code from multiple header files. (You must also use
- `#include' to include the header file; `#pragma implementation'
- only specifies how to use the file--it doesn't actually include
- it.)
-
- There is no way to split up the contents of a single header file
- into multiple implementation files.
-
- `#pragma implementation' and `#pragma interface' also have an effect
-on function inlining.
-
- If you define a class in a header file marked with `#pragma
-interface', the effect on a function defined in that class is similar to
-an explicit `extern' declaration--the compiler emits no code at all to
-define an independent version of the function. Its definition is used
-only for inlining with its callers.
-
- Conversely, when you include the same header file in a main source
-file that declares it as `#pragma implementation', the compiler emits
-code for the function itself; this defines a version of the function
-that can be found via pointers (or by callers compiled without
-inlining). If all calls to the function can be inlined, you can avoid
-emitting the function by compiling with `-fno-implement-inlines'. If
-any calls were not inlined, you will get linker errors.
-
- ---------- Footnotes ----------
-
- (1) A file's "basename" was the name stripped of all leading path
-information and of trailing suffixes, such as `.h' or `.C' or `.cc'.
-
-\1f
-File: gcc.info, Node: Template Instantiation, Next: Bound member functions, Prev: C++ Interface, Up: C++ Extensions
-
-Where's the Template?
-=====================
-
- C++ templates are the first language feature to require more
-intelligence from the environment than one usually finds on a UNIX
-system. Somehow the compiler and linker have to make sure that each
-template instance occurs exactly once in the executable if it is needed,
-and not at all otherwise. There are two basic approaches to this
-problem, which I will refer to as the Borland model and the Cfront
-model.
-
-Borland model
- Borland C++ solved the template instantiation problem by adding
- the code equivalent of common blocks to their linker; the compiler
- emits template instances in each translation unit that uses them,
- and the linker collapses them together. The advantage of this
- model is that the linker only has to consider the object files
- themselves; there is no external complexity to worry about. This
- disadvantage is that compilation time is increased because the
- template code is being compiled repeatedly. Code written for this
- model tends to include definitions of all templates in the header
- file, since they must be seen to be instantiated.
-
-Cfront model
- The AT&T C++ translator, Cfront, solved the template instantiation
- problem by creating the notion of a template repository, an
- automatically maintained place where template instances are
- stored. A more modern version of the repository works as follows:
- As individual object files are built, the compiler places any
- template definitions and instantiations encountered in the
- repository. At link time, the link wrapper adds in the objects in
- the repository and compiles any needed instances that were not
- previously emitted. The advantages of this model are more optimal
- compilation speed and the ability to use the system linker; to
- implement the Borland model a compiler vendor also needs to
- replace the linker. The disadvantages are vastly increased
- complexity, and thus potential for error; for some code this can be
- just as transparent, but in practice it can been very difficult to
- build multiple programs in one directory and one program in
- multiple directories. Code written for this model tends to
- separate definitions of non-inline member templates into a
- separate file, which should be compiled separately.
-
- When used with GNU ld version 2.8 or later on an ELF system such as
-Linux/GNU or Solaris 2, or on Microsoft Windows, g++ supports the
-Borland model. On other systems, g++ implements neither automatic
-model.
-
- A future version of g++ will support a hybrid model whereby the
-compiler will emit any instantiations for which the template definition
-is included in the compile, and store template definitions and
-instantiation context information into the object file for the rest.
-The link wrapper will extract that information as necessary and invoke
-the compiler to produce the remaining instantiations. The linker will
-then combine duplicate instantiations.
-
- In the mean time, you have the following options for dealing with
-template instantiations:
-
- 1. Compile your template-using code with `-frepo'. The compiler will
- generate files with the extension `.rpo' listing all of the
- template instantiations used in the corresponding object files
- which could be instantiated there; the link wrapper, `collect2',
- will then update the `.rpo' files to tell the compiler where to
- place those instantiations and rebuild any affected object files.
- The link-time overhead is negligible after the first pass, as the
- compiler will continue to place the instantiations in the same
- files.
-
- This is your best option for application code written for the
- Borland model, as it will just work. Code written for the Cfront
- model will need to be modified so that the template definitions
- are available at one or more points of instantiation; usually this
- is as simple as adding `#include <tmethods.cc>' to the end of each
- template header.
-
- For library code, if you want the library to provide all of the
- template instantiations it needs, just try to link all of its
- object files together; the link will fail, but cause the
- instantiations to be generated as a side effect. Be warned,
- however, that this may cause conflicts if multiple libraries try
- to provide the same instantiations. For greater control, use
- explicit instantiation as described in the next option.
-
- 2. Compile your code with `-fno-implicit-templates' to disable the
- implicit generation of template instances, and explicitly
- instantiate all the ones you use. This approach requires more
- knowledge of exactly which instances you need than do the others,
- but it's less mysterious and allows greater control. You can
- scatter the explicit instantiations throughout your program,
- perhaps putting them in the translation units where the instances
- are used or the translation units that define the templates
- themselves; you can put all of the explicit instantiations you
- need into one big file; or you can create small files like
-
- #include "Foo.h"
- #include "Foo.cc"
-
- template class Foo<int>;
- template ostream& operator <<
- (ostream&, const Foo<int>&);
-
- for each of the instances you need, and create a template
- instantiation library from those.
-
- If you are using Cfront-model code, you can probably get away with
- not using `-fno-implicit-templates' when compiling files that don't
- `#include' the member template definitions.
-
- If you use one big file to do the instantiations, you may want to
- compile it without `-fno-implicit-templates' so you get all of the
- instances required by your explicit instantiations (but not by any
- other files) without having to specify them as well.
-
- g++ has extended the template instantiation syntax outlined in the
- Working Paper to allow forward declaration of explicit
- instantiations (with `extern'), instantiation of the compiler
- support data for a template class (i.e. the vtable) without
- instantiating any of its members (with `inline'), and
- instantiation of only the static data members of a template class,
- without the support data or member functions (with (`static'):
-
- extern template int max (int, int);
- inline template class Foo<int>;
- static template class Foo<int>;
-
- 3. Do nothing. Pretend g++ does implement automatic instantiation
- management. Code written for the Borland model will work fine, but
- each translation unit will contain instances of each of the
- templates it uses. In a large program, this can lead to an
- unacceptable amount of code duplication.
-
- 4. Add `#pragma interface' to all files containing template
- definitions. For each of these files, add `#pragma implementation
- "FILENAME"' to the top of some `.C' file which `#include's it.
- Then compile everything with `-fexternal-templates'. The
- templates will then only be expanded in the translation unit which
- implements them (i.e. has a `#pragma implementation' line for the
- file where they live); all other files will use external
- references. If you're lucky, everything should work properly. If
- you get undefined symbol errors, you need to make sure that each
- template instance which is used in the program is used in the file
- which implements that template. If you don't have any use for a
- particular instance in that file, you can just instantiate it
- explicitly, using the syntax from the latest C++ working paper:
-
- template class A<int>;
- template ostream& operator << (ostream&, const A<int>&);
-
- This strategy will work with code written for either model. If
- you are using code written for the Cfront model, the file
- containing a class template and the file containing its member
- templates should be implemented in the same translation unit.
-
- 5. A slight variation on this approach is to use the flag
- `-falt-external-templates' instead. This flag causes template
- instances to be emitted in the translation unit that implements the
- header where they are first instantiated, rather than the one which
- implements the file where the templates are defined. This header
- must be the same in all translation units, or things are likely to
- break.
-
- *Note Declarations and Definitions in One Header: C++ Interface,
- for more discussion of these pragmas.
-
-\1f
-File: gcc.info, Node: Bound member functions, Next: C++ Attributes, Prev: Template Instantiation, Up: C++ Extensions
-
-Extracting the function pointer from a bound pointer to member function
-=======================================================================
-
- In C++, pointer to member functions (PMFs) are implemented using a
-wide pointer of sorts to handle all the possible call mechanisms; the
-PMF needs to store information about how to adjust the `this' pointer,
-and if the function pointed to is virtual, where to find the vtable, and
-where in the vtable to look for the member function. If you are using
-PMFs in an inner loop, you should really reconsider that decision. If
-that is not an option, you can extract the pointer to the function that
-would be called for a given object/PMF pair and call it directly inside
-the inner loop, to save a bit of time.
-
- Note that you will still be paying the penalty for the call through a
-function pointer; on most modern architectures, such a call defeats the
-branch prediction features of the CPU. This is also true of normal
-virtual function calls.
-
- The syntax for this extension is
-
- extern A a;
- extern int (A::*fp)();
- typedef int (*fptr)(A *);
-
- fptr p = (fptr)(a.*fp);
-
- For PMF constants (i.e. expressions of the form `&Klasse::Member'),
-no object is needed to obtain the address of the function. They can be
-converted to function pointers directly:
-
- fptr p1 = (fptr)(&A::foo);
-
- You must specify `-Wno-pmf-conversions' to use this extension.
-
-\1f
-File: gcc.info, Node: C++ Attributes, Next: Java Exceptions, Prev: Bound member functions, Up: C++ Extensions
-
-C++-Specific Variable, Function, and Type Attributes
-====================================================
-
- Some attributes only make sense for C++ programs.
-
-`init_priority (PRIORITY)'
- In Standard C++, objects defined at namespace scope are guaranteed
- to be initialized in an order in strict accordance with that of
- their definitions _in a given translation unit_. No guarantee is
- made for initializations across translation units. However, GNU
- C++ allows users to control the order of initialization of objects
- defined at namespace scope with the `init_priority' attribute by
- specifying a relative PRIORITY, a constant integral expression
- currently bounded between 101 and 65535 inclusive. Lower numbers
- indicate a higher priority.
-
- In the following example, `A' would normally be created before
- `B', but the `init_priority' attribute has reversed that order:
-
- Some_Class A __attribute__ ((init_priority (2000)));
- Some_Class B __attribute__ ((init_priority (543)));
-
- Note that the particular values of PRIORITY do not matter; only
- their relative ordering.
-
-`java_interface'
- This type attribute informs C++ that the class is a Java
- interface. It may only be applied to classes declared within an
- `extern "Java"' block. Calls to methods declared in this
- interface will be dispatched using GCJ's interface table
- mechanism, instead of regular virtual table dispatch.
-
-
-\1f
-File: gcc.info, Node: Java Exceptions, Next: Deprecated Features, Prev: C++ Attributes, Up: C++ Extensions
-
-Java Exceptions
-===============
-
- The Java language uses a slightly different exception handling model
-from C++. Normally, GNU C++ will automatically detect when you are
-writing C++ code that uses Java exceptions, and handle them
-appropriately. However, if C++ code only needs to execute destructors
-when Java exceptions are thrown through it, GCC will guess incorrectly.
-Sample problematic code is:
-
- struct S { ~S(); };
- extern void bar(); // is written in Java, and may throw exceptions
- void foo()
- {
- S s;
- bar();
- }
-
-The usual effect of an incorrect guess is a link failure, complaining of
-a missing routine called `__gxx_personality_v0'.
-
- You can inform the compiler that Java exceptions are to be used in a
-translation unit, irrespective of what it might think, by writing
-`#pragma GCC java_exceptions' at the head of the file. This `#pragma'
-must appear before any functions that throw or catch exceptions, or run
-destructors when exceptions are thrown through them.
-
- You cannot mix Java and C++ exceptions in the same translation unit.
-It is believed to be safe to throw a C++ exception from one file
-through another file compiled for the Java exception model, or vice
-versa, but there may be bugs in this area.
-
-\1f
-File: gcc.info, Node: Deprecated Features, Next: Backwards Compatibility, Prev: Java Exceptions, Up: C++ Extensions
-
-Deprecated Features
-===================
-
- In the past, the GNU C++ compiler was extended to experiment with new
-features, at a time when the C++ language was still evolving. Now that
-the C++ standard is complete, some of those features are superseded by
-superior alternatives. Using the old features might cause a warning in
-some cases that the feature will be dropped in the future. In other
-cases, the feature might be gone already.
-
- While the list below is not exhaustive, it documents some of the
-options that are now deprecated:
-
-`-fexternal-templates'
-`-falt-external-templates'
- These are two of the many ways for g++ to implement template
- instantiation. *Note Template Instantiation::. The C++ standard
- clearly defines how template definitions have to be organized
- across implementation units. g++ has an implicit instantiation
- mechanism that should work just fine for standard-conforming code.
-
-`-fstrict-prototype'
-`-fno-strict-prototype'
- Previously it was possible to use an empty prototype parameter
- list to indicate an unspecified number of parameters (like C),
- rather than no parameters, as C++ demands. This feature has been
- removed, except where it is required for backwards compatibility
- *Note Backwards Compatibility::.
-
- The named return value extension has been deprecated, and is now
-removed from g++.
-
- The use of initializer lists with new expressions has been
-deprecated, and is now removed from g++.
-
- Floating and complex non-type template parameters have been
-deprecated, and are now removed from g++.
-
- The implicit typename extension has been deprecated and will be
-removed from g++ at some point. In some cases g++ determines that a
-dependant type such as `TPL<T>::X' is a type without needing a
-`typename' keyword, contrary to the standard.
-
-\1f
-File: gcc.info, Node: Backwards Compatibility, Prev: Deprecated Features, Up: C++ Extensions
-
-Backwards Compatibility
-=======================
-
- Now that there is a definitive ISO standard C++, G++ has a
-specification to adhere to. The C++ language evolved over time, and
-features that used to be acceptable in previous drafts of the standard,
-such as the ARM [Annotated C++ Reference Manual], are no longer
-accepted. In order to allow compilation of C++ written to such drafts,
-G++ contains some backwards compatibilities. _All such backwards
-compatibility features are liable to disappear in future versions of
-G++._ They should be considered deprecated *Note Deprecated Features::.
-
-`For scope'
- If a variable is declared at for scope, it used to remain in scope
- until the end of the scope which contained the for statement
- (rather than just within the for scope). G++ retains this, but
- issues a warning, if such a variable is accessed outside the for
- scope.
-
-`Implicit C language'
- Old C system header files did not contain an `extern "C" {...}'
- scope to set the language. On such systems, all header files are
- implicitly scoped inside a C language scope. Also, an empty
- prototype `()' will be treated as an unspecified number of
- arguments, rather than no arguments, as C++ demands.
-
-\1f
-File: gcc.info, Node: Objective-C, Next: Compatibility, Prev: C++ Extensions, Up: Top
-
-GNU Objective-C runtime features
-********************************
-
- This document is meant to describe some of the GNU Objective-C
-runtime features. It is not intended to teach you Objective-C, there
-are several resources on the Internet that present the language.
-Questions and comments about this document to Ovidiu Predescu
-<ovidiu@cup.hp.com>.
-
-* Menu:
-
-* Executing code before main::
-* Type encoding::
-* Garbage Collection::
-* Constant string objects::
-* compatibility_alias::
-
-\1f
-File: gcc.info, Node: Executing code before main, Next: Type encoding, Prev: Objective-C, Up: Objective-C
-
-`+load': Executing code before main
-===================================
-
- The GNU Objective-C runtime provides a way that allows you to execute
-code before the execution of the program enters the `main' function.
-The code is executed on a per-class and a per-category basis, through a
-special class method `+load'.
-
- This facility is very useful if you want to initialize global
-variables which can be accessed by the program directly, without
-sending a message to the class first. The usual way to initialize
-global variables, in the `+initialize' method, might not be useful
-because `+initialize' is only called when the first message is sent to a
-class object, which in some cases could be too late.
-
- Suppose for example you have a `FileStream' class that declares
-`Stdin', `Stdout' and `Stderr' as global variables, like below:
-
-
- FileStream *Stdin = nil;
- FileStream *Stdout = nil;
- FileStream *Stderr = nil;
-
- @implementation FileStream
-
- + (void)initialize
- {
- Stdin = [[FileStream new] initWithFd:0];
- Stdout = [[FileStream new] initWithFd:1];
- Stderr = [[FileStream new] initWithFd:2];
- }
-
- /* Other methods here */
- @end
-
- In this example, the initialization of `Stdin', `Stdout' and
-`Stderr' in `+initialize' occurs too late. The programmer can send a
-message to one of these objects before the variables are actually
-initialized, thus sending messages to the `nil' object. The
-`+initialize' method which actually initializes the global variables is
-not invoked until the first message is sent to the class object. The
-solution would require these variables to be initialized just before
-entering `main'.
-
- The correct solution of the above problem is to use the `+load'
-method instead of `+initialize':
-
-
- @implementation FileStream
-
- + (void)load
- {
- Stdin = [[FileStream new] initWithFd:0];
- Stdout = [[FileStream new] initWithFd:1];
- Stderr = [[FileStream new] initWithFd:2];
- }
-
- /* Other methods here */
- @end
-
- The `+load' is a method that is not overridden by categories. If a
-class and a category of it both implement `+load', both methods are
-invoked. This allows some additional initializations to be performed in
-a category.
-
- This mechanism is not intended to be a replacement for `+initialize'.
-You should be aware of its limitations when you decide to use it
-instead of `+initialize'.
-
-* Menu:
-
-* What you can and what you cannot do in +load::
-
-\1f
-File: gcc.info, Node: What you can and what you cannot do in +load, Prev: Executing code before main, Up: Executing code before main
-
-What you can and what you cannot do in `+load'
-----------------------------------------------
-
- The `+load' implementation in the GNU runtime guarantees you the
-following things:
-
- * you can write whatever C code you like;
-
- * you can send messages to Objective-C constant strings (`@"this is a
- constant string"');
-
- * you can allocate and send messages to objects whose class is
- implemented in the same file;
-
- * the `+load' implementation of all super classes of a class are
- executed before the `+load' of that class is executed;
-
- * the `+load' implementation of a class is executed before the
- `+load' implementation of any category.
-
-
- In particular, the following things, even if they can work in a
-particular case, are not guaranteed:
-
- * allocation of or sending messages to arbitrary objects;
-
- * allocation of or sending messages to objects whose classes have a
- category implemented in the same file;
-
-
- You should make no assumptions about receiving `+load' in sibling
-classes when you write `+load' of a class. The order in which sibling
-classes receive `+load' is not guaranteed.
-
- The order in which `+load' and `+initialize' are called could be
-problematic if this matters. If you don't allocate objects inside
-`+load', it is guaranteed that `+load' is called before `+initialize'.
-If you create an object inside `+load' the `+initialize' method of
-object's class is invoked even if `+load' was not invoked. Note if you
-explicitly call `+load' on a class, `+initialize' will be called first.
-To avoid possible problems try to implement only one of these methods.
-
- The `+load' method is also invoked when a bundle is dynamically
-loaded into your running program. This happens automatically without
-any intervening operation from you. When you write bundles and you
-need to write `+load' you can safely create and send messages to
-objects whose classes already exist in the running program. The same
-restrictions as above apply to classes defined in bundle.
-
-\1f
-File: gcc.info, Node: Type encoding, Next: Garbage Collection, Prev: Executing code before main, Up: Objective-C
-
-Type encoding
-=============
-
- The Objective-C compiler generates type encodings for all the types.
-These type encodings are used at runtime to find out information about
-selectors and methods and about objects and classes.
-
- The types are encoded in the following way:
-
-`char' `c'
-`unsigned char' `C'
-`short' `s'
-`unsigned short' `S'
-`int' `i'
-`unsigned int' `I'
-`long' `l'
-`unsigned long' `L'
-`long long' `q'
-`unsigned long `Q'
-long'
-`float' `f'
-`double' `d'
-`void' `v'
-`id' `@'
-`Class' `#'
-`SEL' `:'
-`char*' `*'
-unknown type `?'
-bit-fields `b' followed by the starting position of the
- bit-field, the type of the bit-field and the size of
- the bit-field (the bit-fields encoding was changed
- from the NeXT's compiler encoding, see below)
-
- The encoding of bit-fields has changed to allow bit-fields to be
-properly handled by the runtime functions that compute sizes and
-alignments of types that contain bit-fields. The previous encoding
-contained only the size of the bit-field. Using only this information
-it is not possible to reliably compute the size occupied by the
-bit-field. This is very important in the presence of the Boehm's
-garbage collector because the objects are allocated using the typed
-memory facility available in this collector. The typed memory
-allocation requires information about where the pointers are located
-inside the object.
-
- The position in the bit-field is the position, counting in bits, of
-the bit closest to the beginning of the structure.
-
- The non-atomic types are encoded as follows:
-
-pointers `^' followed by the pointed type.
-arrays `[' followed by the number of elements in the array
- followed by the type of the elements followed by `]'
-structures `{' followed by the name of the structure (or `?' if the
- structure is unnamed), the `=' sign, the type of the
- members and by `}'
-unions `(' followed by the name of the structure (or `?' if the
- union is unnamed), the `=' sign, the type of the members
- followed by `)'
-
- Here are some types and their encodings, as they are generated by the
-compiler on an i386 machine:
-
-
-Objective-C type Compiler encoding
- int a[10]; `[10i]'
- struct { `{?=i[3f]b128i3b131i2c}'
- int i;
- float f[3];
- int a:3;
- int b:2;
- char c;
- }
-
-
- In addition to the types the compiler also encodes the type
-specifiers. The table below describes the encoding of the current
-Objective-C type specifiers:
-
-
-Specifier Encoding
-`const' `r'
-`in' `n'
-`inout' `N'
-`out' `o'
-`bycopy' `O'
-`oneway' `V'
-
-
- The type specifiers are encoded just before the type. Unlike types
-however, the type specifiers are only encoded when they appear in method
-argument types.
-
-\1f
-File: gcc.info, Node: Garbage Collection, Next: Constant string objects, Prev: Type encoding, Up: Objective-C
-
-Garbage Collection
-==================
-
- Support for a new memory management policy has been added by using a
-powerful conservative garbage collector, known as the
-Boehm-Demers-Weiser conservative garbage collector. It is available
-from `http://www.hpl.hp.com/personal/Hans_Boehm/gc/'.
-
- To enable the support for it you have to configure the compiler
-using an additional argument, `--enable-objc-gc'. You need to have
-garbage collector installed before building the compiler. This will
-build an additional runtime library which has several enhancements to
-support the garbage collector. The new library has a new name,
-`libobjc_gc.a' to not conflict with the non-garbage-collected library.
-
- When the garbage collector is used, the objects are allocated using
-the so-called typed memory allocation mechanism available in the
-Boehm-Demers-Weiser collector. This mode requires precise information
-on where pointers are located inside objects. This information is
-computed once per class, immediately after the class has been
-initialized.
-
- There is a new runtime function `class_ivar_set_gcinvisible()' which
-can be used to declare a so-called "weak pointer" reference. Such a
-pointer is basically hidden for the garbage collector; this can be
-useful in certain situations, especially when you want to keep track of
-the allocated objects, yet allow them to be collected. This kind of
-pointers can only be members of objects, you cannot declare a global
-pointer as a weak reference. Every type which is a pointer type can be
-declared a weak pointer, including `id', `Class' and `SEL'.
-
- Here is an example of how to use this feature. Suppose you want to
-implement a class whose instances hold a weak pointer reference; the
-following class does this:
-
-
- @interface WeakPointer : Object
- {
- const void* weakPointer;
- }
-
- - initWithPointer:(const void*)p;
- - (const void*)weakPointer;
- @end
-
-
- @implementation WeakPointer
-
- + (void)initialize
- {
- class_ivar_set_gcinvisible (self, "weakPointer", YES);
- }
-
- - initWithPointer:(const void*)p
- {
- weakPointer = p;
- return self;
- }
-
- - (const void*)weakPointer
- {
- return weakPointer;
- }
-
- @end
-
- Weak pointers are supported through a new type character specifier
-represented by the `!' character. The `class_ivar_set_gcinvisible()'
-function adds or removes this specifier to the string type description
-of the instance variable named as argument.
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Constant string objects, Next: compatibility_alias, Prev: Garbage Collection, Up: Objective-C
-
-Constant string objects
-=======================
-
- GNU Objective-C provides constant string objects that are generated
-directly by the compiler. You declare a constant string object by
-prefixing a C constant string with the character `@':
-
- id myString = @"this is a constant string object";
-
- The constant string objects are usually instances of the
-`NXConstantString' class which is provided by the GNU Objective-C
-runtime. To get the definition of this class you must include the
-`objc/NXConstStr.h' header file.
-
- User defined libraries may want to implement their own constant
-string class. To be able to support them, the GNU Objective-C compiler
-provides a new command line options
-`-fconstant-string-class=CLASS-NAME'. The provided class should adhere
-to a strict structure, the same as `NXConstantString''s structure:
-
-
- @interface NXConstantString : Object
- {
- char *c_string;
- unsigned int len;
- }
- @end
-
- User class libraries may choose to inherit the customized constant
-string class from a different class than `Object'. There is no
-requirement in the methods the constant string class has to implement.
-
- When a file is compiled with the `-fconstant-string-class' option,
-all the constant string objects will be instances of the class specified
-as argument to this option. It is possible to have multiple compilation
-units referring to different constant string classes, neither the
-compiler nor the linker impose any restrictions in doing this.
-
-\1f
-File: gcc.info, Node: compatibility_alias, Prev: Constant string objects, Up: Objective-C
-
-compatibility_alias
-===================
-
- This is a feature of the Objective-C compiler rather than of the
-runtime, anyway since it is documented nowhere and its existence was
-forgotten, we are documenting it here.
-
- The keyword `@compatibility_alias' allows you to define a class name
-as equivalent to another class name. For example:
-
- @compatibility_alias WOApplication GSWApplication;
-
- tells the compiler that each time it encounters `WOApplication' as a
-class name, it should replace it with `GSWApplication' (that is,
-`WOApplication' is just an alias for `GSWApplication').
-
- There are some constraints on how this can be used--
-
- * `WOApplication' (the alias) must not be an existing class;
-
- * `GSWApplication' (the real class) must be an existing class.
-
-
-\1f
-File: gcc.info, Node: Compatibility, Next: Gcov, Prev: Objective-C, Up: Top
-
-Binary Compatibility
-********************
-
- Binary compatibility encompasses several related concepts:
-
-"application binary interface (ABI)"
- The set of runtime conventions followed by all of the tools that
- deal with binary representations of a program, including
- compilers, assemblers, linkers, and language runtime support.
- Some ABIs are formal with a written specification, possibly
- designed by multiple interested parties. Others are simply the
- way things are actually done by a particular set of tools.
-
-"ABI conformance"
- A compiler conforms to an ABI if it generates code that follows
- all of the specifications enumerated by that ABI. A library
- conforms to an ABI if it is implemented according to that ABI. An
- application conforms to an ABI if it is built using tools that
- conform to that ABI and does not contain source code that
- specifically changes behavior specified by the ABI.
-
-"calling conventions"
- Calling conventions are a subset of an ABI that specify of how
- arguments are passed and function results are returned.
-
-"interoperability"
- Different sets of tools are interoperable if they generate files
- that can be used in the same program. The set of tools includes
- compilers, assemblers, linkers, libraries, header files, startup
- files, and debuggers. Binaries produced by different sets of
- tools are not interoperable unless they implement the same ABI.
- This applies to different versions of the same tools as well as
- tools from different vendors.
-
-"intercallability"
- Whether a function in a binary built by one set of tools can call a
- function in a binary built by a different set of tools is a subset
- of interoperability.
-
-"implementation-defined features"
- Language standards include lists of implementation-defined
- features whose behavior can vary from one implementation to
- another. Some of these features are normally covered by a
- platform's ABI and others are not. The features that are not
- covered by an ABI generally affect how a program behaves, but not
- intercallability.
-
-"compatibility"
- Conformance to the same ABI and the same behavior of
- implementation-defined features are both relevant for
- compatibility.
-
- The application binary interface implemented by a C or C++ compiler
-affects code generation and runtime support for:
-
- * size and alignment of data types
-
- * layout of structured types
-
- * calling conventions
-
- * register usage conventions
-
- * interfaces for runtime arithmetic support
-
- * object file formats
-
- In addition, the application binary interface implemented by a C++
-compiler affects code generation and runtime support for:
- * name mangling
-
- * exception handling
-
- * invoking constructors and destructors
-
- * layout, alignment, and padding of classes
-
- * layout and alignment of virtual tables
-
- Some GCC compilation options cause the compiler to generate code that
-does not conform to the platform's default ABI. Other options cause
-different program behavior for implementation-defined features that are
-not covered by an ABI. These options are provided for consistency with
-other compilers that do not follow the platform's default ABI or the
-usual behavior of implementation-defined features for the platform. Be
-very careful about using such options.
-
- Most platforms have a well-defined ABI that covers C code, but ABIs
-that cover C++ functionality are not yet common.
-
- Starting with GCC 3.2, GCC binary conventions for C++ are based on a
-written, vendor-neutral C++ ABI that was designed to be specific to
-64-bit Itanium but also includes generic specifications that apply to
-any platform. This C++ ABI is also implemented by other compiler
-vendors on some platforms, notably GNU/Linux and BSD systems. We have
-tried hard to provide a stable ABI that will be compatible with future
-GCC releases, but it is possible that we will encounter problems that
-make this difficult. Such problems could include different
-interpretations of the C++ ABI by different vendors, bugs in the ABI, or
-bugs in the implementation of the ABI in different compilers. GCC's
-`-Wabi' switch warns when G++ generates code that is probably not
-compatible with the C++ ABI.
-
- The C++ library used with a C++ compiler includes the Standard C++
-Library, with functionality defined in the C++ Standard, plus language
-runtime support. The runtime support is included in a C++ ABI, but
-there is no formal ABI for the Standard C++ Library. Two
-implementations of that library are interoperable if one follows the
-de-facto ABI of the other and if they are both built with the same
-compiler, or with compilers that conform to the same ABI for C++
-compiler and runtime support.
-
- When G++ and another C++ compiler conform to the same C++ ABI, but
-the implementations of the Standard C++ Library that they normally use
-do not follow the same ABI for the Standard C++ Library, object files
-built with those compilers can be used in the same program only if they
-use the same C++ library. This requires specifying the location of the
-C++ library header files when invoking the compiler whose usual library
-is not being used. The location of GCC's C++ header files depends on
-how the GCC build was configured, but can be seen by using the G++ `-v'
-option. With default configuration options for G++ 3.2 the compile
-line for a different C++ compiler needs to include
-
- -IGCC_INSTALL_DIRECTORY/include/c++/3.2
-
- Similarly, compiling code with G++ that must use a C++ library other
-than the GNU C++ library requires specifying the location of the header
-files for that other library.
-
- The most straightforward way to link a program to use a particular
-C++ library is to use a C++ driver that specifies that C++ library by
-default. The `g++' driver, for example, tells the linker where to find
-GCC's C++ library (`libstdc++') plus the other libraries and startup
-files it needs, in the proper order.
-
- If a program must use a different C++ library and it's not possible
-to do the final link using a C++ driver that uses that library by
-default, it is necessary to tell `g++' the location and name of that
-library. It might also be necessary to specify different startup files
-and other runtime support libraries, and to suppress the use of GCC's
-support libraries with one or more of the options `-nostdlib',
-`-nostartfiles', and `-nodefaultlibs'.
-
-\1f
-File: gcc.info, Node: Gcov, Next: Trouble, Prev: Compatibility, Up: Top
-
-`gcov'--a Test Coverage Program
-*******************************
-
- `gcov' is a tool you can use in conjunction with GCC to test code
-coverage in your programs.
-
-* Menu:
-
-* Gcov Intro:: Introduction to gcov.
-* Invoking Gcov:: How to use gcov.
-* Gcov and Optimization:: Using gcov with GCC optimization.
-* Gcov Data Files:: The files used by gcov.
-
-\1f
-File: gcc.info, Node: Gcov Intro, Next: Invoking Gcov, Up: Gcov
-
-Introduction to `gcov'
-======================
-
- `gcov' is a test coverage program. Use it in concert with GCC to
-analyze your programs to help create more efficient, faster running
-code. You can use `gcov' as a profiling tool to help discover where
-your optimization efforts will best affect your code. You can also use
-`gcov' along with the other profiling tool, `gprof', to assess which
-parts of your code use the greatest amount of computing time.
-
- Profiling tools help you analyze your code's performance. Using a
-profiler such as `gcov' or `gprof', you can find out some basic
-performance statistics, such as:
-
- * how often each line of code executes
-
- * what lines of code are actually executed
-
- * how much computing time each section of code uses
-
- Once you know these things about how your code works when compiled,
-you can look at each module to see which modules should be optimized.
-`gcov' helps you determine where to work on optimization.
-
- Software developers also use coverage testing in concert with
-testsuites, to make sure software is actually good enough for a release.
-Testsuites can verify that a program works as expected; a coverage
-program tests to see how much of the program is exercised by the
-testsuite. Developers can then determine what kinds of test cases need
-to be added to the testsuites to create both better testing and a better
-final product.
-
- You should compile your code without optimization if you plan to use
-`gcov' because the optimization, by combining some lines of code into
-one function, may not give you as much information as you need to look
-for `hot spots' where the code is using a great deal of computer time.
-Likewise, because `gcov' accumulates statistics by line (at the lowest
-resolution), it works best with a programming style that places only
-one statement on each line. If you use complicated macros that expand
-to loops or to other control structures, the statistics are less
-helpful--they only report on the line where the macro call appears. If
-your complex macros behave like functions, you can replace them with
-inline functions to solve this problem.
-
- `gcov' creates a logfile called `SOURCEFILE.gcov' which indicates
-how many times each line of a source file `SOURCEFILE.c' has executed.
-You can use these logfiles along with `gprof' to aid in fine-tuning the
-performance of your programs. `gprof' gives timing information you can
-use along with the information you get from `gcov'.
-
- `gcov' works only on code compiled with GCC. It is not compatible
-with any other profiling or test coverage mechanism.
-
-\1f
-File: gcc.info, Node: Invoking Gcov, Next: Gcov and Optimization, Prev: Gcov Intro, Up: Gcov
-
-Invoking gcov
-=============
-
- gcov [OPTIONS] SOURCEFILE
-
- `gcov' accepts the following options:
-
-`-h'
-`--help'
- Display help about using `gcov' (on the standard output), and exit
- without doing any further processing.
-
-`-v'
-`--version'
- Display the `gcov' version number (on the standard output), and
- exit without doing any further processing.
-
-`-b'
-`--branch-probabilities'
- Write branch frequencies to the output file, and write branch
- summary info to the standard output. This option allows you to
- see how often each branch in your program was taken.
-
-`-c'
-`--branch-counts'
- Write branch frequencies as the number of branches taken, rather
- than the percentage of branches taken.
-
-`-n'
-`--no-output'
- Do not create the `gcov' output file.
-
-`-l'
-`--long-file-names'
- Create long file names for included source files. For example, if
- the header file `x.h' contains code, and was included in the file
- `a.c', then running `gcov' on the file `a.c' will produce an
- output file called `a.c.x.h.gcov' instead of `x.h.gcov'. This can
- be useful if `x.h' is included in multiple source files.
-
-`-f'
-`--function-summaries'
- Output summaries for each function in addition to the file level
- summary.
-
-`-o DIRECTORY'
-`--object-directory DIRECTORY'
- The directory where the object files live. Gcov will search for
- `.bb', `.bbg', and `.da' files in this directory.
-
- When using `gcov', you must first compile your program with two
-special GCC options: `-fprofile-arcs -ftest-coverage'. This tells the
-compiler to generate additional information needed by gcov (basically a
-flow graph of the program) and also includes additional code in the
-object files for generating the extra profiling information needed by
-gcov. These additional files are placed in the directory where the
-source code is located.
-
- Running the program will cause profile output to be generated. For
-each source file compiled with `-fprofile-arcs', an accompanying `.da'
-file will be placed in the source directory.
-
- Running `gcov' with your program's source file names as arguments
-will now produce a listing of the code along with frequency of execution
-for each line. For example, if your program is called `tmp.c', this is
-what you see when you use the basic `gcov' facility:
-
- $ gcc -fprofile-arcs -ftest-coverage tmp.c
- $ a.out
- $ gcov tmp.c
- 87.50% of 8 source lines executed in file tmp.c
- Creating tmp.c.gcov.
-
- The file `tmp.c.gcov' contains output from `gcov'. Here is a sample:
-
- main()
- {
- 1 int i, total;
-
- 1 total = 0;
-
- 11 for (i = 0; i < 10; i++)
- 10 total += i;
-
- 1 if (total != 45)
- ###### printf ("Failure\n");
- else
- 1 printf ("Success\n");
- 1 }
-
- When you use the `-b' option, your output looks like this:
-
- $ gcov -b tmp.c
- 87.50% of 8 source lines executed in file tmp.c
- 80.00% of 5 branches executed in file tmp.c
- 80.00% of 5 branches taken at least once in file tmp.c
- 50.00% of 2 calls executed in file tmp.c
- Creating tmp.c.gcov.
-
- Here is a sample of a resulting `tmp.c.gcov' file:
-
- main()
- {
- 1 int i, total;
-
- 1 total = 0;
-
- 11 for (i = 0; i < 10; i++)
- branch 0 taken = 91%
- branch 1 taken = 100%
- branch 2 taken = 100%
- 10 total += i;
-
- 1 if (total != 45)
- branch 0 taken = 100%
- ###### printf ("Failure\n");
- call 0 never executed
- branch 1 never executed
- else
- 1 printf ("Success\n");
- call 0 returns = 100%
- 1 }
-
- For each basic block, a line is printed after the last line of the
-basic block describing the branch or call that ends the basic block.
-There can be multiple branches and calls listed for a single source
-line if there are multiple basic blocks that end on that line. In this
-case, the branches and calls are each given a number. There is no
-simple way to map these branches and calls back to source constructs.
-In general, though, the lowest numbered branch or call will correspond
-to the leftmost construct on the source line.
-
- For a branch, if it was executed at least once, then a percentage
-indicating the number of times the branch was taken divided by the
-number of times the branch was executed will be printed. Otherwise, the
-message "never executed" is printed.
-
- For a call, if it was executed at least once, then a percentage
-indicating the number of times the call returned divided by the number
-of times the call was executed will be printed. This will usually be
-100%, but may be less for functions call `exit' or `longjmp', and thus
-may not return every time they are called.
-
- The execution counts are cumulative. If the example program were
-executed again without removing the `.da' file, the count for the
-number of times each line in the source was executed would be added to
-the results of the previous run(s). This is potentially useful in
-several ways. For example, it could be used to accumulate data over a
-number of program runs as part of a test verification suite, or to
-provide more accurate long-term information over a large number of
-program runs.
-
- The data in the `.da' files is saved immediately before the program
-exits. For each source file compiled with `-fprofile-arcs', the
-profiling code first attempts to read in an existing `.da' file; if the
-file doesn't match the executable (differing number of basic block
-counts) it will ignore the contents of the file. It then adds in the
-new execution counts and finally writes the data to the file.
-
-\1f
-File: gcc.info, Node: Gcov and Optimization, Next: Gcov Data Files, Prev: Invoking Gcov, Up: Gcov
-
-Using `gcov' with GCC Optimization
-==================================
-
- If you plan to use `gcov' to help optimize your code, you must first
-compile your program with two special GCC options: `-fprofile-arcs
--ftest-coverage'. Aside from that, you can use any other GCC options;
-but if you want to prove that every single line in your program was
-executed, you should not compile with optimization at the same time.
-On some machines the optimizer can eliminate some simple code lines by
-combining them with other lines. For example, code like this:
-
- if (a != b)
- c = 1;
- else
- c = 0;
-
-can be compiled into one instruction on some machines. In this case,
-there is no way for `gcov' to calculate separate execution counts for
-each line because there isn't separate code for each line. Hence the
-`gcov' output looks like this if you compiled the program with
-optimization:
-
- 100 if (a != b)
- 100 c = 1;
- 100 else
- 100 c = 0;
-
- The output shows that this block of code, combined by optimization,
-executed 100 times. In one sense this result is correct, because there
-was only one instruction representing all four of these lines. However,
-the output does not indicate how many times the result was 0 and how
-many times the result was 1.
-
-\1f
-File: gcc.info, Node: Gcov Data Files, Prev: Gcov and Optimization, Up: Gcov
-
-Brief description of `gcov' data files
-======================================
-
- `gcov' uses three files for doing profiling. The names of these
-files are derived from the original _source_ file by substituting the
-file suffix with either `.bb', `.bbg', or `.da'. All of these files
-are placed in the same directory as the source file, and contain data
-stored in a platform-independent method.
-
- The `.bb' and `.bbg' files are generated when the source file is
-compiled with the GCC `-ftest-coverage' option. The `.bb' file
-contains a list of source files (including headers), functions within
-those files, and line numbers corresponding to each basic block in the
-source file.
-
- The `.bb' file format consists of several lists of 4-byte integers
-which correspond to the line numbers of each basic block in the file.
-Each list is terminated by a line number of 0. A line number of -1 is
-used to designate that the source file name (padded to a 4-byte
-boundary and followed by another -1) follows. In addition, a line
-number of -2 is used to designate that the name of a function (also
-padded to a 4-byte boundary and followed by a -2) follows.
-
- The `.bbg' file is used to reconstruct the program flow graph for
-the source file. It contains a list of the program flow arcs (possible
-branches taken from one basic block to another) for each function which,
-in combination with the `.bb' file, enables gcov to reconstruct the
-program flow.
-
- In the `.bbg' file, the format is:
- number of basic blocks for function #0 (4-byte number)
- total number of arcs for function #0 (4-byte number)
- count of arcs in basic block #0 (4-byte number)
- destination basic block of arc #0 (4-byte number)
- flag bits (4-byte number)
- destination basic block of arc #1 (4-byte number)
- flag bits (4-byte number)
- ...
- destination basic block of arc #N (4-byte number)
- flag bits (4-byte number)
- count of arcs in basic block #1 (4-byte number)
- destination basic block of arc #0 (4-byte number)
- flag bits (4-byte number)
- ...
-
- A -1 (stored as a 4-byte number) is used to separate each function's
-list of basic blocks, and to verify that the file has been read
-correctly.
-
- The `.da' file is generated when a program containing object files
-built with the GCC `-fprofile-arcs' option is executed. A separate
-`.da' file is created for each source file compiled with this option,
-and the name of the `.da' file is stored as an absolute pathname in the
-resulting object file. This path name is derived from the source file
-name by substituting a `.da' suffix.
-
- The format of the `.da' file is fairly simple. The first 8-byte
-number is the number of counts in the file, followed by the counts
-(stored as 8-byte numbers). Each count corresponds to the number of
-times each arc in the program is executed. The counts are cumulative;
-each time the program is executed, it attempts to combine the existing
-`.da' files with the new counts for this invocation of the program. It
-ignores the contents of any `.da' files whose number of arcs doesn't
-correspond to the current program, and merely overwrites them instead.
-
- All three of these files use the functions in `gcov-io.h' to store
-integers; the functions in this header provide a machine-independent
-mechanism for storing and retrieving data from a stream.
-
-\1f
-File: gcc.info, Node: Trouble, Next: Bugs, Prev: Gcov, Up: Top
-
-Known Causes of Trouble with GCC
-********************************
-
- This section describes known problems that affect users of GCC. Most
-of these are not GCC bugs per se--if they were, we would fix them. But
-the result for a user may be like the result of a bug.
-
- Some of these problems are due to bugs in other software, some are
-missing features that are too much work to add, and some are places
-where people's opinions differ as to what is best.
-
-* Menu:
-
-* Actual Bugs:: Bugs we will fix later.
-* Cross-Compiler Problems:: Common problems of cross compiling with GCC.
-* Interoperation:: Problems using GCC with other compilers,
- and with certain linkers, assemblers and debuggers.
-* External Bugs:: Problems compiling certain programs.
-* Incompatibilities:: GCC is incompatible with traditional C.
-* Fixed Headers:: GCC uses corrected versions of system header files.
- This is necessary, but doesn't always work smoothly.
-* Standard Libraries:: GCC uses the system C library, which might not be
- compliant with the ISO C standard.
-* Disappointments:: Regrettable things we can't change, but not quite bugs.
-* C++ Misunderstandings:: Common misunderstandings with GNU C++.
-* Protoize Caveats:: Things to watch out for when using `protoize'.
-* Non-bugs:: Things we think are right, but some others disagree.
-* Warnings and Errors:: Which problems in your code get warnings,
- and which get errors.
-
-\1f
-File: gcc.info, Node: Actual Bugs, Next: Cross-Compiler Problems, Up: Trouble
-
-Actual Bugs We Haven't Fixed Yet
-================================
-
- * The `fixincludes' script interacts badly with automounters; if the
- directory of system header files is automounted, it tends to be
- unmounted while `fixincludes' is running. This would seem to be a
- bug in the automounter. We don't know any good way to work around
- it.
-
- * The `fixproto' script will sometimes add prototypes for the
- `sigsetjmp' and `siglongjmp' functions that reference the
- `jmp_buf' type before that type is defined. To work around this,
- edit the offending file and place the typedef in front of the
- prototypes.
-
- * When `-pedantic-errors' is specified, GCC will incorrectly give an
- error message when a function name is specified in an expression
- involving the comma operator.
-
-\1f
-File: gcc.info, Node: Cross-Compiler Problems, Next: Interoperation, Prev: Actual Bugs, Up: Trouble
-
-Cross-Compiler Problems
-=======================
-
- You may run into problems with cross compilation on certain machines,
-for several reasons.
-
- * Cross compilation can run into trouble for certain machines because
- some target machines' assemblers require floating point numbers to
- be written as _integer_ constants in certain contexts.
-
- The compiler writes these integer constants by examining the
- floating point value as an integer and printing that integer,
- because this is simple to write and independent of the details of
- the floating point representation. But this does not work if the
- compiler is running on a different machine with an incompatible
- floating point format, or even a different byte-ordering.
-
- In addition, correct constant folding of floating point values
- requires representing them in the target machine's format. (The C
- standard does not quite require this, but in practice it is the
- only way to win.)
-
- It is now possible to overcome these problems by defining macros
- such as `REAL_VALUE_TYPE'. But doing so is a substantial amount of
- work for each target machine. *Note Cross Compilation and
- Floating Point: (gccint)Cross-compilation.
-
- * At present, the program `mips-tfile' which adds debug support to
- object files on MIPS systems does not work in a cross compile
- environment.
-
-\1f
-File: gcc.info, Node: Interoperation, Next: External Bugs, Prev: Cross-Compiler Problems, Up: Trouble
-
-Interoperation
-==============
-
- This section lists various difficulties encountered in using GCC
-together with other compilers or with the assemblers, linkers,
-libraries and debuggers on certain systems.
-
- * On many platforms, GCC supports a different ABI for C++ than do
- other compilers, so the object files compiled by GCC cannot be
- used with object files generated by another C++ compiler.
-
- An area where the difference is most apparent is name mangling.
- The use of different name mangling is intentional, to protect you
- from more subtle problems. Compilers differ as to many internal
- details of C++ implementation, including: how class instances are
- laid out, how multiple inheritance is implemented, and how virtual
- function calls are handled. If the name encoding were made the
- same, your programs would link against libraries provided from
- other compilers--but the programs would then crash when run.
- Incompatible libraries are then detected at link time, rather than
- at run time.
-
- * Older GDB versions sometimes fail to read the output of GCC version
- 2. If you have trouble, get GDB version 4.4 or later.
-
- * DBX rejects some files produced by GCC, though it accepts similar
- constructs in output from PCC. Until someone can supply a coherent
- description of what is valid DBX input and what is not, there is
- nothing I can do about these problems. You are on your own.
-
- * The GNU assembler (GAS) does not support PIC. To generate PIC
- code, you must use some other assembler, such as `/bin/as'.
-
- * On some BSD systems, including some versions of Ultrix, use of
- profiling causes static variable destructors (currently used only
- in C++) not to be run.
-
- * On some SGI systems, when you use `-lgl_s' as an option, it gets
- translated magically to `-lgl_s -lX11_s -lc_s'. Naturally, this
- does not happen when you use GCC. You must specify all three
- options explicitly.
-
- * On a Sparc, GCC aligns all values of type `double' on an 8-byte
- boundary, and it expects every `double' to be so aligned. The Sun
- compiler usually gives `double' values 8-byte alignment, with one
- exception: function arguments of type `double' may not be aligned.
-
- As a result, if a function compiled with Sun CC takes the address
- of an argument of type `double' and passes this pointer of type
- `double *' to a function compiled with GCC, dereferencing the
- pointer may cause a fatal signal.
-
- One way to solve this problem is to compile your entire program
- with GCC. Another solution is to modify the function that is
- compiled with Sun CC to copy the argument into a local variable;
- local variables are always properly aligned. A third solution is
- to modify the function that uses the pointer to dereference it via
- the following function `access_double' instead of directly with
- `*':
-
- inline double
- access_double (double *unaligned_ptr)
- {
- union d2i { double d; int i[2]; };
-
- union d2i *p = (union d2i *) unaligned_ptr;
- union d2i u;
-
- u.i[0] = p->i[0];
- u.i[1] = p->i[1];
-
- return u.d;
- }
-
- Storing into the pointer can be done likewise with the same union.
-
- * On Solaris, the `malloc' function in the `libmalloc.a' library may
- allocate memory that is only 4 byte aligned. Since GCC on the
- Sparc assumes that doubles are 8 byte aligned, this may result in a
- fatal signal if doubles are stored in memory allocated by the
- `libmalloc.a' library.
-
- The solution is to not use the `libmalloc.a' library. Use instead
- `malloc' and related functions from `libc.a'; they do not have
- this problem.
-
- * Sun forgot to include a static version of `libdl.a' with some
- versions of SunOS (mainly 4.1). This results in undefined symbols
- when linking static binaries (that is, if you use `-static'). If
- you see undefined symbols `_dlclose', `_dlsym' or `_dlopen' when
- linking, compile and link against the file `mit/util/misc/dlsym.c'
- from the MIT version of X windows.
-
- * The 128-bit long double format that the Sparc port supports
- currently works by using the architecturally defined quad-word
- floating point instructions. Since there is no hardware that
- supports these instructions they must be emulated by the operating
- system. Long doubles do not work in Sun OS versions 4.0.3 and
- earlier, because the kernel emulator uses an obsolete and
- incompatible format. Long doubles do not work in Sun OS version
- 4.1.1 due to a problem in a Sun library. Long doubles do work on
- Sun OS versions 4.1.2 and higher, but GCC does not enable them by
- default. Long doubles appear to work in Sun OS 5.x (Solaris 2.x).
-
- * On HP-UX version 9.01 on the HP PA, the HP compiler `cc' does not
- compile GCC correctly. We do not yet know why. However, GCC
- compiled on earlier HP-UX versions works properly on HP-UX 9.01
- and can compile itself properly on 9.01.
-
- * On the HP PA machine, ADB sometimes fails to work on functions
- compiled with GCC. Specifically, it fails to work on functions
- that use `alloca' or variable-size arrays. This is because GCC
- doesn't generate HP-UX unwind descriptors for such functions. It
- may even be impossible to generate them.
-
- * Debugging (`-g') is not supported on the HP PA machine, unless you
- use the preliminary GNU tools.
-
- * Taking the address of a label may generate errors from the HP-UX
- PA assembler. GAS for the PA does not have this problem.
-
- * Using floating point parameters for indirect calls to static
- functions will not work when using the HP assembler. There simply
- is no way for GCC to specify what registers hold arguments for
- static functions when using the HP assembler. GAS for the PA does
- not have this problem.
-
- * In extremely rare cases involving some very large functions you may
- receive errors from the HP linker complaining about an out of
- bounds unconditional branch offset. This used to occur more often
- in previous versions of GCC, but is now exceptionally rare. If
- you should run into it, you can work around by making your
- function smaller.
-
- * GCC compiled code sometimes emits warnings from the HP-UX
- assembler of the form:
-
- (warning) Use of GR3 when
- frame >= 8192 may cause conflict.
-
- These warnings are harmless and can be safely ignored.
-
- * On the IBM RS/6000, compiling code of the form
-
- extern int foo;
-
- ... foo ...
-
- static int foo;
-
- will cause the linker to report an undefined symbol `foo'.
- Although this behavior differs from most other systems, it is not a
- bug because redefining an `extern' variable as `static' is
- undefined in ISO C.
-
- * In extremely rare cases involving some very large functions you may
- receive errors from the AIX Assembler complaining about a
- displacement that is too large. If you should run into it, you
- can work around by making your function smaller.
-
- * The `libstdc++.a' library in GCC relies on the SVR4 dynamic linker
- semantics which merges global symbols between libraries and
- applications, especially necessary for C++ streams functionality.
- This is not the default behavior of AIX shared libraries and
- dynamic linking. `libstdc++.a' is built on AIX with
- "runtime-linking" enabled so that symbol merging can occur. To
- utilize this feature, the application linked with `libstdc++.a'
- must include the `-Wl,-brtl' flag on the link line. G++ cannot
- impose this because this option may interfere with the semantics
- of the user program and users may not always use `g++' to link his
- or her application. Applications are not required to use the
- `-Wl,-brtl' flag on the link line--the rest of the `libstdc++.a'
- library which is not dependent on the symbol merging semantics
- will continue to function correctly.
-
- * An application can interpose its own definition of functions for
- functions invoked by `libstdc++.a' with "runtime-linking" enabled
- on AIX. To accomplish this the application must be linked with
- "runtime-linking" option and the functions explicitly must be
- exported by the application (`-Wl,-brtl,-bE:exportfile').
-
- * AIX on the RS/6000 provides support (NLS) for environments outside
- of the United States. Compilers and assemblers use NLS to support
- locale-specific representations of various objects including
- floating-point numbers (`.' vs `,' for separating decimal
- fractions). There have been problems reported where the library
- linked with GCC does not produce the same floating-point formats
- that the assembler accepts. If you have this problem, set the
- `LANG' environment variable to `C' or `En_US'.
-
- * Even if you specify `-fdollars-in-identifiers', you cannot
- successfully use `$' in identifiers on the RS/6000 due to a
- restriction in the IBM assembler. GAS supports these identifiers.
-
- * There is an assembler bug in versions of DG/UX prior to 5.4.2.01
- that occurs when the `fldcr' instruction is used. GCC uses
- `fldcr' on the 88100 to serialize volatile memory references. Use
- the option `-mno-serialize-volatile' if your version of the
- assembler has this bug.
-
- * On VMS, GAS versions 1.38.1 and earlier may cause spurious warning
- messages from the linker. These warning messages complain of
- mismatched psect attributes. You can ignore them.
-
- * On NewsOS version 3, if you include both of the files `stddef.h'
- and `sys/types.h', you get an error because there are two typedefs
- of `size_t'. You should change `sys/types.h' by adding these
- lines around the definition of `size_t':
-
- #ifndef _SIZE_T
- #define _SIZE_T
- ACTUAL-TYPEDEF-HERE
- #endif
-
- * On the Alliant, the system's own convention for returning
- structures and unions is unusual, and is not compatible with GCC
- no matter what options are used.
-
- * On the IBM RT PC, the MetaWare HighC compiler (hc) uses a different
- convention for structure and union returning. Use the option
- `-mhc-struct-return' to tell GCC to use a convention compatible
- with it.
-
- * On Ultrix, the Fortran compiler expects registers 2 through 5 to
- be saved by function calls. However, the C compiler uses
- conventions compatible with BSD Unix: registers 2 through 5 may be
- clobbered by function calls.
-
- GCC uses the same convention as the Ultrix C compiler. You can use
- these options to produce code compatible with the Fortran compiler:
-
- -fcall-saved-r2 -fcall-saved-r3 -fcall-saved-r4 -fcall-saved-r5
-
- * On the WE32k, you may find that programs compiled with GCC do not
- work with the standard shared C library. You may need to link with
- the ordinary C compiler. If you do so, you must specify the
- following options:
-
- -L/usr/local/lib/gcc-lib/we32k-att-sysv/2.8.1 -lgcc -lc_s
-
- The first specifies where to find the library `libgcc.a' specified
- with the `-lgcc' option.
-
- GCC does linking by invoking `ld', just as `cc' does, and there is
- no reason why it _should_ matter which compilation program you use
- to invoke `ld'. If someone tracks this problem down, it can
- probably be fixed easily.
-
- * On the Alpha, you may get assembler errors about invalid syntax as
- a result of floating point constants. This is due to a bug in the
- C library functions `ecvt', `fcvt' and `gcvt'. Given valid
- floating point numbers, they sometimes print `NaN'.
-
- * On Irix 4.0.5F (and perhaps in some other versions), an assembler
- bug sometimes reorders instructions incorrectly when optimization
- is turned on. If you think this may be happening to you, try
- using the GNU assembler; GAS version 2.1 supports ECOFF on Irix.
-
- Or use the `-noasmopt' option when you compile GCC with itself,
- and then again when you compile your program. (This is a temporary
- kludge to turn off assembler optimization on Irix.) If this
- proves to be what you need, edit the assembler spec in the file
- `specs' so that it unconditionally passes `-O0' to the assembler,
- and never passes `-O2' or `-O3'.
-
-\1f
-File: gcc.info, Node: External Bugs, Next: Incompatibilities, Prev: Interoperation, Up: Trouble
-
-Problems Compiling Certain Programs
-===================================
-
- Certain programs have problems compiling.
-
- * Parse errors may occur compiling X11 on a Decstation running
- Ultrix 4.2 because of problems in DEC's versions of the X11 header
- files `X11/Xlib.h' and `X11/Xutil.h'. People recommend adding
- `-I/usr/include/mit' to use the MIT versions of the header files,
- using the `-traditional' switch to turn off ISO C, or fixing the
- header files by adding this:
-
- #ifdef __STDC__
- #define NeedFunctionPrototypes 0
- #endif
-
- * On various 386 Unix systems derived from System V, including SCO,
- ISC, and ESIX, you may get error messages about running out of
- virtual memory while compiling certain programs.
-
- You can prevent this problem by linking GCC with the GNU malloc
- (which thus replaces the malloc that comes with the system). GNU
- malloc is available as a separate package, and also in the file
- `src/gmalloc.c' in the GNU Emacs 19 distribution.
-
- If you have installed GNU malloc as a separate library package,
- use this option when you relink GCC:
-
- MALLOC=/usr/local/lib/libgmalloc.a
-
- Alternatively, if you have compiled `gmalloc.c' from Emacs 19, copy
- the object file to `gmalloc.o' and use this option when you relink
- GCC:
-
- MALLOC=gmalloc.o
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Incompatibilities, Next: Fixed Headers, Prev: External Bugs, Up: Trouble
-
-Incompatibilities of GCC
-========================
-
- There are several noteworthy incompatibilities between GNU C and K&R
-(non-ISO) versions of C. The `-traditional' option eliminates many of
-these incompatibilities, _but not all_, by telling GCC to behave like a
-K&R C compiler.
-
- * GCC normally makes string constants read-only. If several
- identical-looking string constants are used, GCC stores only one
- copy of the string.
-
- One consequence is that you cannot call `mktemp' with a string
- constant argument. The function `mktemp' always alters the string
- its argument points to.
-
- Another consequence is that `sscanf' does not work on some systems
- when passed a string constant as its format control string or
- input. This is because `sscanf' incorrectly tries to write into
- the string constant. Likewise `fscanf' and `scanf'.
-
- The best solution to these problems is to change the program to use
- `char'-array variables with initialization strings for these
- purposes instead of string constants. But if this is not possible,
- you can use the `-fwritable-strings' flag, which directs GCC to
- handle string constants the same way most C compilers do.
- `-traditional' also has this effect, among others.
-
- * `-2147483648' is positive.
-
- This is because 2147483648 cannot fit in the type `int', so
- (following the ISO C rules) its data type is `unsigned long int'.
- Negating this value yields 2147483648 again.
-
- * GCC does not substitute macro arguments when they appear inside of
- string constants. For example, the following macro in GCC
-
- #define foo(a) "a"
-
- will produce output `"a"' regardless of what the argument A is.
-
- The `-traditional' option directs GCC to handle such cases (among
- others) in the old-fashioned (non-ISO) fashion.
-
- * When you use `setjmp' and `longjmp', the only automatic variables
- guaranteed to remain valid are those declared `volatile'. This is
- a consequence of automatic register allocation. Consider this
- function:
-
- jmp_buf j;
-
- foo ()
- {
- int a, b;
-
- a = fun1 ();
- if (setjmp (j))
- return a;
-
- a = fun2 ();
- /* `longjmp (j)' may occur in `fun3'. */
- return a + fun3 ();
- }
-
- Here `a' may or may not be restored to its first value when the
- `longjmp' occurs. If `a' is allocated in a register, then its
- first value is restored; otherwise, it keeps the last value stored
- in it.
-
- If you use the `-W' option with the `-O' option, you will get a
- warning when GCC thinks such a problem might be possible.
-
- The `-traditional' option directs GCC to put variables in the
- stack by default, rather than in registers, in functions that call
- `setjmp'. This results in the behavior found in traditional C
- compilers.
-
- * Programs that use preprocessing directives in the middle of macro
- arguments do not work with GCC. For example, a program like this
- will not work:
-
- foobar (
- #define luser
- hack)
-
- ISO C does not permit such a construct. It would make sense to
- support it when `-traditional' is used, but it is too much work to
- implement.
-
- * K&R compilers allow comments to cross over an inclusion boundary
- (i.e. started in an include file and ended in the including file).
- I think this would be quite ugly and can't imagine it could be
- needed.
-
- * Declarations of external variables and functions within a block
- apply only to the block containing the declaration. In other
- words, they have the same scope as any other declaration in the
- same place.
-
- In some other C compilers, a `extern' declaration affects all the
- rest of the file even if it happens within a block.
-
- The `-traditional' option directs GCC to treat all `extern'
- declarations as global, like traditional compilers.
-
- * In traditional C, you can combine `long', etc., with a typedef
- name, as shown here:
-
- typedef int foo;
- typedef long foo bar;
-
- In ISO C, this is not allowed: `long' and other type modifiers
- require an explicit `int'. Because this criterion is expressed by
- Bison grammar rules rather than C code, the `-traditional' flag
- cannot alter it.
-
- * PCC allows typedef names to be used as function parameters. The
- difficulty described immediately above applies here too.
-
- * When in `-traditional' mode, GCC allows the following erroneous
- pair of declarations to appear together in a given scope:
-
- typedef int foo;
- typedef foo foo;
-
- * GCC treats all characters of identifiers as significant, even when
- in `-traditional' mode. According to K&R-1 (2.2), "No more than
- the first eight characters are significant, although more may be
- used.". Also according to K&R-1 (2.2), "An identifier is a
- sequence of letters and digits; the first character must be a
- letter. The underscore _ counts as a letter.", but GCC also
- allows dollar signs in identifiers.
-
- * PCC allows whitespace in the middle of compound assignment
- operators such as `+='. GCC, following the ISO standard, does not
- allow this. The difficulty described immediately above applies
- here too.
-
- * GCC complains about unterminated character constants inside of
- preprocessing conditionals that fail. Some programs have English
- comments enclosed in conditionals that are guaranteed to fail; if
- these comments contain apostrophes, GCC will probably report an
- error. For example, this code would produce an error:
-
- #if 0
- You can't expect this to work.
- #endif
-
- The best solution to such a problem is to put the text into an
- actual C comment delimited by `/*...*/'. However, `-traditional'
- suppresses these error messages.
-
- * Many user programs contain the declaration `long time ();'. In the
- past, the system header files on many systems did not actually
- declare `time', so it did not matter what type your program
- declared it to return. But in systems with ISO C headers, `time'
- is declared to return `time_t', and if that is not the same as
- `long', then `long time ();' is erroneous.
-
- The solution is to change your program to use appropriate system
- headers (`<time.h>' on systems with ISO C headers) and not to
- declare `time' if the system header files declare it, or failing
- that to use `time_t' as the return type of `time'.
-
- * When compiling functions that return `float', PCC converts it to a
- double. GCC actually returns a `float'. If you are concerned
- with PCC compatibility, you should declare your functions to return
- `double'; you might as well say what you mean.
-
- * When compiling functions that return structures or unions, GCC
- output code normally uses a method different from that used on most
- versions of Unix. As a result, code compiled with GCC cannot call
- a structure-returning function compiled with PCC, and vice versa.
-
- The method used by GCC is as follows: a structure or union which is
- 1, 2, 4 or 8 bytes long is returned like a scalar. A structure or
- union with any other size is stored into an address supplied by
- the caller (usually in a special, fixed register, but on some
- machines it is passed on the stack). The machine-description
- macros `STRUCT_VALUE' and `STRUCT_INCOMING_VALUE' tell GCC where
- to pass this address.
-
- By contrast, PCC on most target machines returns structures and
- unions of any size by copying the data into an area of static
- storage, and then returning the address of that storage as if it
- were a pointer value. The caller must copy the data from that
- memory area to the place where the value is wanted. GCC does not
- use this method because it is slower and nonreentrant.
-
- On some newer machines, PCC uses a reentrant convention for all
- structure and union returning. GCC on most of these machines uses
- a compatible convention when returning structures and unions in
- memory, but still returns small structures and unions in registers.
-
- You can tell GCC to use a compatible convention for all structure
- and union returning with the option `-fpcc-struct-return'.
-
- * GCC complains about program fragments such as `0x74ae-0x4000'
- which appear to be two hexadecimal constants separated by the minus
- operator. Actually, this string is a single "preprocessing token".
- Each such token must correspond to one token in C. Since this
- does not, GCC prints an error message. Although it may appear
- obvious that what is meant is an operator and two values, the ISO
- C standard specifically requires that this be treated as erroneous.
-
- A "preprocessing token" is a "preprocessing number" if it begins
- with a digit and is followed by letters, underscores, digits,
- periods and `e+', `e-', `E+', `E-', `p+', `p-', `P+', or `P-'
- character sequences. (In strict C89 mode, the sequences `p+',
- `p-', `P+' and `P-' cannot appear in preprocessing numbers.)
-
- To make the above program fragment valid, place whitespace in
- front of the minus sign. This whitespace will end the
- preprocessing number.
-
-\1f
-File: gcc.info, Node: Fixed Headers, Next: Standard Libraries, Prev: Incompatibilities, Up: Trouble
-
-Fixed Header Files
-==================
-
- GCC needs to install corrected versions of some system header files.
-This is because most target systems have some header files that won't
-work with GCC unless they are changed. Some have bugs, some are
-incompatible with ISO C, and some depend on special features of other
-compilers.
-
- Installing GCC automatically creates and installs the fixed header
-files, by running a program called `fixincludes' (or for certain
-targets an alternative such as `fixinc.svr4'). Normally, you don't
-need to pay attention to this. But there are cases where it doesn't do
-the right thing automatically.
-
- * If you update the system's header files, such as by installing a
- new system version, the fixed header files of GCC are not
- automatically updated. The easiest way to update them is to
- reinstall GCC. (If you want to be clever, look in the makefile
- and you can find a shortcut.)
-
- * On some systems, in particular SunOS 4, header file directories
- contain machine-specific symbolic links in certain places. This
- makes it possible to share most of the header files among hosts
- running the same version of SunOS 4 on different machine models.
-
- The programs that fix the header files do not understand this
- special way of using symbolic links; therefore, the directory of
- fixed header files is good only for the machine model used to
- build it.
-
- In SunOS 4, only programs that look inside the kernel will notice
- the difference between machine models. Therefore, for most
- purposes, you need not be concerned about this.
-
- It is possible to make separate sets of fixed header files for the
- different machine models, and arrange a structure of symbolic
- links so as to use the proper set, but you'll have to do this by
- hand.
-
- * On Lynxos, GCC by default does not fix the header files. This is
- because bugs in the shell cause the `fixincludes' script to fail.
-
- This means you will encounter problems due to bugs in the system
- header files. It may be no comfort that they aren't GCC's fault,
- but it does mean that there's nothing for us to do about them.
-
-\1f
-File: gcc.info, Node: Standard Libraries, Next: Disappointments, Prev: Fixed Headers, Up: Trouble
-
-Standard Libraries
-==================
-
- GCC by itself attempts to be a conforming freestanding
-implementation. *Note Language Standards Supported by GCC: Standards,
-for details of what this means. Beyond the library facilities required
-of such an implementation, the rest of the C library is supplied by the
-vendor of the operating system. If that C library doesn't conform to
-the C standards, then your programs might get warnings (especially when
-using `-Wall') that you don't expect.
-
- For example, the `sprintf' function on SunOS 4.1.3 returns `char *'
-while the C standard says that `sprintf' returns an `int'. The
-`fixincludes' program could make the prototype for this function match
-the Standard, but that would be wrong, since the function will still
-return `char *'.
-
- If you need a Standard compliant library, then you need to find one,
-as GCC does not provide one. The GNU C library (called `glibc')
-provides ISO C, POSIX, BSD, SystemV and X/Open compatibility for
-GNU/Linux and HURD-based GNU systems; no recent version of it supports
-other systems, though some very old versions did. Version 2.2 of the
-GNU C library includes nearly complete C99 support. You could also ask
-your operating system vendor if newer libraries are available.
-
-\1f
-File: gcc.info, Node: Disappointments, Next: C++ Misunderstandings, Prev: Standard Libraries, Up: Trouble
-
-Disappointments and Misunderstandings
-=====================================
-
- These problems are perhaps regrettable, but we don't know any
-practical way around them.
-
- * Certain local variables aren't recognized by debuggers when you
- compile with optimization.
-
- This occurs because sometimes GCC optimizes the variable out of
- existence. There is no way to tell the debugger how to compute the
- value such a variable "would have had", and it is not clear that
- would be desirable anyway. So GCC simply does not mention the
- eliminated variable when it writes debugging information.
-
- You have to expect a certain amount of disagreement between the
- executable and your source code, when you use optimization.
-
- * Users often think it is a bug when GCC reports an error for code
- like this:
-
- int foo (struct mumble *);
-
- struct mumble { ... };
-
- int foo (struct mumble *x)
- { ... }
-
- This code really is erroneous, because the scope of `struct
- mumble' in the prototype is limited to the argument list
- containing it. It does not refer to the `struct mumble' defined
- with file scope immediately below--they are two unrelated types
- with similar names in different scopes.
-
- But in the definition of `foo', the file-scope type is used
- because that is available to be inherited. Thus, the definition
- and the prototype do not match, and you get an error.
-
- This behavior may seem silly, but it's what the ISO standard
- specifies. It is easy enough for you to make your code work by
- moving the definition of `struct mumble' above the prototype.
- It's not worth being incompatible with ISO C just to avoid an
- error for the example shown above.
-
- * Accesses to bit-fields even in volatile objects works by accessing
- larger objects, such as a byte or a word. You cannot rely on what
- size of object is accessed in order to read or write the
- bit-field; it may even vary for a given bit-field according to the
- precise usage.
-
- If you care about controlling the amount of memory that is
- accessed, use volatile but do not use bit-fields.
-
- * GCC comes with shell scripts to fix certain known problems in
- system header files. They install corrected copies of various
- header files in a special directory where only GCC will normally
- look for them. The scripts adapt to various systems by searching
- all the system header files for the problem cases that we know
- about.
-
- If new system header files are installed, nothing automatically
- arranges to update the corrected header files. You will have to
- reinstall GCC to fix the new header files. More specifically, go
- to the build directory and delete the files `stmp-fixinc' and
- `stmp-headers', and the subdirectory `include'; then do `make
- install' again.
-
- * On 68000 and x86 systems, for instance, you can get paradoxical
- results if you test the precise values of floating point numbers.
- For example, you can find that a floating point value which is not
- a NaN is not equal to itself. This results from the fact that the
- floating point registers hold a few more bits of precision than
- fit in a `double' in memory. Compiled code moves values between
- memory and floating point registers at its convenience, and moving
- them into memory truncates them.
-
- You can partially avoid this problem by using the `-ffloat-store'
- option (*note Optimize Options::).
-
- * On the MIPS, variable argument functions using `varargs.h' cannot
- have a floating point value for the first argument. The reason
- for this is that in the absence of a prototype in scope, if the
- first argument is a floating point, it is passed in a floating
- point register, rather than an integer register.
-
- If the code is rewritten to use the ISO standard `stdarg.h' method
- of variable arguments, and the prototype is in scope at the time
- of the call, everything will work fine.
-
- * On the H8/300 and H8/300H, variable argument functions must be
- implemented using the ISO standard `stdarg.h' method of variable
- arguments. Furthermore, calls to functions using `stdarg.h'
- variable arguments must have a prototype for the called function
- in scope at the time of the call.
-
- * On AIX and other platforms without weak symbol support, templates
- need to be instantiated explicitly and symbols for static members
- of templates will not be generated.
-
-\1f
-File: gcc.info, Node: C++ Misunderstandings, Next: Protoize Caveats, Prev: Disappointments, Up: Trouble
-
-Common Misunderstandings with GNU C++
-=====================================
-
- C++ is a complex language and an evolving one, and its standard
-definition (the ISO C++ standard) was only recently completed. As a
-result, your C++ compiler may occasionally surprise you, even when its
-behavior is correct. This section discusses some areas that frequently
-give rise to questions of this sort.
-
-* Menu:
-
-* Static Definitions:: Static member declarations are not definitions
-* Temporaries:: Temporaries may vanish before you expect
-* Copy Assignment:: Copy Assignment operators copy virtual bases twice
-
-\1f
-File: gcc.info, Node: Static Definitions, Next: Temporaries, Up: C++ Misunderstandings
-
-Declare _and_ Define Static Members
------------------------------------
-
- When a class has static data members, it is not enough to _declare_
-the static member; you must also _define_ it. For example:
-
- class Foo
- {
- ...
- void method();
- static int bar;
- };
-
- This declaration only establishes that the class `Foo' has an `int'
-named `Foo::bar', and a member function named `Foo::method'. But you
-still need to define _both_ `method' and `bar' elsewhere. According to
-the ISO standard, you must supply an initializer in one (and only one)
-source file, such as:
-
- int Foo::bar = 0;
-
- Other C++ compilers may not correctly implement the standard
-behavior. As a result, when you switch to `g++' from one of these
-compilers, you may discover that a program that appeared to work
-correctly in fact does not conform to the standard: `g++' reports as
-undefined symbols any static data members that lack definitions.
-
-\1f
-File: gcc.info, Node: Temporaries, Next: Copy Assignment, Prev: Static Definitions, Up: C++ Misunderstandings
-
-Temporaries May Vanish Before You Expect
-----------------------------------------
-
- It is dangerous to use pointers or references to _portions_ of a
-temporary object. The compiler may very well delete the object before
-you expect it to, leaving a pointer to garbage. The most common place
-where this problem crops up is in classes like string classes,
-especially ones that define a conversion function to type `char *' or
-`const char *'--which is one reason why the standard `string' class
-requires you to call the `c_str' member function. However, any class
-that returns a pointer to some internal structure is potentially
-subject to this problem.
-
- For example, a program may use a function `strfunc' that returns
-`string' objects, and another function `charfunc' that operates on
-pointers to `char':
-
- string strfunc ();
- void charfunc (const char *);
-
- void
- f ()
- {
- const char *p = strfunc().c_str();
- ...
- charfunc (p);
- ...
- charfunc (p);
- }
-
-In this situation, it may seem reasonable to save a pointer to the C
-string returned by the `c_str' member function and use that rather than
-call `c_str' repeatedly. However, the temporary string created by the
-call to `strfunc' is destroyed after `p' is initialized, at which point
-`p' is left pointing to freed memory.
-
- Code like this may run successfully under some other compilers,
-particularly obsolete cfront-based compilers that delete temporaries
-along with normal local variables. However, the GNU C++ behavior is
-standard-conforming, so if your program depends on late destruction of
-temporaries it is not portable.
-
- The safe way to write such code is to give the temporary a name,
-which forces it to remain until the end of the scope of the name. For
-example:
-
- string& tmp = strfunc ();
- charfunc (tmp.c_str ());
-
-\1f
-File: gcc.info, Node: Copy Assignment, Prev: Temporaries, Up: C++ Misunderstandings
-
-Implicit Copy-Assignment for Virtual Bases
-------------------------------------------
-
- When a base class is virtual, only one subobject of the base class
-belongs to each full object. Also, the constructors and destructors are
-invoked only once, and called from the most-derived class. However,
-such objects behave unspecified when being assigned. For example:
-
- struct Base{
- char *name;
- Base(char *n) : name(strdup(n)){}
- Base& operator= (const Base& other){
- free (name);
- name = strdup (other.name);
- }
- };
-
- struct A:virtual Base{
- int val;
- A():Base("A"){}
- };
-
- struct B:virtual Base{
- int bval;
- B():Base("B"){}
- };
-
- struct Derived:public A, public B{
- Derived():Base("Derived"){}
- };
-
- void func(Derived &d1, Derived &d2)
- {
- d1 = d2;
- }
-
- The C++ standard specifies that `Base::Base' is only called once
-when constructing or copy-constructing a Derived object. It is
-unspecified whether `Base::operator=' is called more than once when the
-implicit copy-assignment for Derived objects is invoked (as it is
-inside `func' in the example).
-
- g++ implements the "intuitive" algorithm for copy-assignment: assign
-all direct bases, then assign all members. In that algorithm, the
-virtual base subobject can be encountered many times. In the example,
-copying proceeds in the following order: `val', `name' (via `strdup'),
-`bval', and `name' again.
-
- If application code relies on copy-assignment, a user-defined
-copy-assignment operator removes any uncertainties. With such an
-operator, the application can define whether and how the virtual base
-subobject is assigned.
-
-\1f
-File: gcc.info, Node: Protoize Caveats, Next: Non-bugs, Prev: C++ Misunderstandings, Up: Trouble
-
-Caveats of using `protoize'
-===========================
-
- The conversion programs `protoize' and `unprotoize' can sometimes
-change a source file in a way that won't work unless you rearrange it.
-
- * `protoize' can insert references to a type name or type tag before
- the definition, or in a file where they are not defined.
-
- If this happens, compiler error messages should show you where the
- new references are, so fixing the file by hand is straightforward.
-
- * There are some C constructs which `protoize' cannot figure out.
- For example, it can't determine argument types for declaring a
- pointer-to-function variable; this you must do by hand. `protoize'
- inserts a comment containing `???' each time it finds such a
- variable; so you can find all such variables by searching for this
- string. ISO C does not require declaring the argument types of
- pointer-to-function types.
-
- * Using `unprotoize' can easily introduce bugs. If the program
- relied on prototypes to bring about conversion of arguments, these
- conversions will not take place in the program without prototypes.
- One case in which you can be sure `unprotoize' is safe is when you
- are removing prototypes that were made with `protoize'; if the
- program worked before without any prototypes, it will work again
- without them.
-
- You can find all the places where this problem might occur by
- compiling the program with the `-Wconversion' option. It prints a
- warning whenever an argument is converted.
-
- * Both conversion programs can be confused if there are macro calls
- in and around the text to be converted. In other words, the
- standard syntax for a declaration or definition must not result
- from expanding a macro. This problem is inherent in the design of
- C and cannot be fixed. If only a few functions have confusing
- macro calls, you can easily convert them manually.
-
- * `protoize' cannot get the argument types for a function whose
- definition was not actually compiled due to preprocessing
- conditionals. When this happens, `protoize' changes nothing in
- regard to such a function. `protoize' tries to detect such
- instances and warn about them.
-
- You can generally work around this problem by using `protoize' step
- by step, each time specifying a different set of `-D' options for
- compilation, until all of the functions have been converted.
- There is no automatic way to verify that you have got them all,
- however.
-
- * Confusion may result if there is an occasion to convert a function
- declaration or definition in a region of source code where there
- is more than one formal parameter list present. Thus, attempts to
- convert code containing multiple (conditionally compiled) versions
- of a single function header (in the same vicinity) may not produce
- the desired (or expected) results.
-
- If you plan on converting source files which contain such code, it
- is recommended that you first make sure that each conditionally
- compiled region of source code which contains an alternative
- function header also contains at least one additional follower
- token (past the final right parenthesis of the function header).
- This should circumvent the problem.
-
- * `unprotoize' can become confused when trying to convert a function
- definition or declaration which contains a declaration for a
- pointer-to-function formal argument which has the same name as the
- function being defined or declared. We recommend you avoid such
- choices of formal parameter names.
-
- * You might also want to correct some of the indentation by hand and
- break long lines. (The conversion programs don't write lines
- longer than eighty characters in any case.)
-
-\1f
-File: gcc.info, Node: Non-bugs, Next: Warnings and Errors, Prev: Protoize Caveats, Up: Trouble
-
-Certain Changes We Don't Want to Make
-=====================================
-
- This section lists changes that people frequently request, but which
-we do not make because we think GCC is better without them.
-
- * Checking the number and type of arguments to a function which has
- an old-fashioned definition and no prototype.
-
- Such a feature would work only occasionally--only for calls that
- appear in the same file as the called function, following the
- definition. The only way to check all calls reliably is to add a
- prototype for the function. But adding a prototype eliminates the
- motivation for this feature. So the feature is not worthwhile.
-
- * Warning about using an expression whose type is signed as a shift
- count.
-
- Shift count operands are probably signed more often than unsigned.
- Warning about this would cause far more annoyance than good.
-
- * Warning about assigning a signed value to an unsigned variable.
-
- Such assignments must be very common; warning about them would
- cause more annoyance than good.
-
- * Warning when a non-void function value is ignored.
-
- Coming as I do from a Lisp background, I balk at the idea that
- there is something dangerous about discarding a value. There are
- functions that return values which some callers may find useful;
- it makes no sense to clutter the program with a cast to `void'
- whenever the value isn't useful.
-
- * Making `-fshort-enums' the default.
-
- This would cause storage layout to be incompatible with most other
- C compilers. And it doesn't seem very important, given that you
- can get the same result in other ways. The case where it matters
- most is when the enumeration-valued object is inside a structure,
- and in that case you can specify a field width explicitly.
-
- * Making bit-fields unsigned by default on particular machines where
- "the ABI standard" says to do so.
-
- The ISO C standard leaves it up to the implementation whether a
- bit-field declared plain `int' is signed or not. This in effect
- creates two alternative dialects of C.
-
- The GNU C compiler supports both dialects; you can specify the
- signed dialect with `-fsigned-bitfields' and the unsigned dialect
- with `-funsigned-bitfields'. However, this leaves open the
- question of which dialect to use by default.
-
- Currently, the preferred dialect makes plain bit-fields signed,
- because this is simplest. Since `int' is the same as `signed int'
- in every other context, it is cleanest for them to be the same in
- bit-fields as well.
-
- Some computer manufacturers have published Application Binary
- Interface standards which specify that plain bit-fields should be
- unsigned. It is a mistake, however, to say anything about this
- issue in an ABI. This is because the handling of plain bit-fields
- distinguishes two dialects of C. Both dialects are meaningful on
- every type of machine. Whether a particular object file was
- compiled using signed bit-fields or unsigned is of no concern to
- other object files, even if they access the same bit-fields in the
- same data structures.
-
- A given program is written in one or the other of these two
- dialects. The program stands a chance to work on most any machine
- if it is compiled with the proper dialect. It is unlikely to work
- at all if compiled with the wrong dialect.
-
- Many users appreciate the GNU C compiler because it provides an
- environment that is uniform across machines. These users would be
- inconvenienced if the compiler treated plain bit-fields
- differently on certain machines.
-
- Occasionally users write programs intended only for a particular
- machine type. On these occasions, the users would benefit if the
- GNU C compiler were to support by default the same dialect as the
- other compilers on that machine. But such applications are rare.
- And users writing a program to run on more than one type of
- machine cannot possibly benefit from this kind of compatibility.
-
- This is why GCC does and will treat plain bit-fields in the same
- fashion on all types of machines (by default).
-
- There are some arguments for making bit-fields unsigned by default
- on all machines. If, for example, this becomes a universal de
- facto standard, it would make sense for GCC to go along with it.
- This is something to be considered in the future.
-
- (Of course, users strongly concerned about portability should
- indicate explicitly in each bit-field whether it is signed or not.
- In this way, they write programs which have the same meaning in
- both C dialects.)
-
- * Undefining `__STDC__' when `-ansi' is not used.
-
- Currently, GCC defines `__STDC__' as long as you don't use
- `-traditional'. This provides good results in practice.
-
- Programmers normally use conditionals on `__STDC__' to ask whether
- it is safe to use certain features of ISO C, such as function
- prototypes or ISO token concatenation. Since plain `gcc' supports
- all the features of ISO C, the correct answer to these questions is
- "yes".
-
- Some users try to use `__STDC__' to check for the availability of
- certain library facilities. This is actually incorrect usage in
- an ISO C program, because the ISO C standard says that a conforming
- freestanding implementation should define `__STDC__' even though it
- does not have the library facilities. `gcc -ansi -pedantic' is a
- conforming freestanding implementation, and it is therefore
- required to define `__STDC__', even though it does not come with
- an ISO C library.
-
- Sometimes people say that defining `__STDC__' in a compiler that
- does not completely conform to the ISO C standard somehow violates
- the standard. This is illogical. The standard is a standard for
- compilers that claim to support ISO C, such as `gcc -ansi'--not
- for other compilers such as plain `gcc'. Whatever the ISO C
- standard says is relevant to the design of plain `gcc' without
- `-ansi' only for pragmatic reasons, not as a requirement.
-
- GCC normally defines `__STDC__' to be 1, and in addition defines
- `__STRICT_ANSI__' if you specify the `-ansi' option, or a `-std'
- option for strict conformance to some version of ISO C. On some
- hosts, system include files use a different convention, where
- `__STDC__' is normally 0, but is 1 if the user specifies strict
- conformance to the C Standard. GCC follows the host convention
- when processing system include files, but when processing user
- files it follows the usual GNU C convention.
-
- * Undefining `__STDC__' in C++.
-
- Programs written to compile with C++-to-C translators get the
- value of `__STDC__' that goes with the C compiler that is
- subsequently used. These programs must test `__STDC__' to
- determine what kind of C preprocessor that compiler uses: whether
- they should concatenate tokens in the ISO C fashion or in the
- traditional fashion.
-
- These programs work properly with GNU C++ if `__STDC__' is defined.
- They would not work otherwise.
-
- In addition, many header files are written to provide prototypes
- in ISO C but not in traditional C. Many of these header files can
- work without change in C++ provided `__STDC__' is defined. If
- `__STDC__' is not defined, they will all fail, and will all need
- to be changed to test explicitly for C++ as well.
-
- * Deleting "empty" loops.
-
- Historically, GCC has not deleted "empty" loops under the
- assumption that the most likely reason you would put one in a
- program is to have a delay, so deleting them will not make real
- programs run any faster.
-
- However, the rationale here is that optimization of a nonempty loop
- cannot produce an empty one, which holds for C but is not always
- the case for C++.
-
- Moreover, with `-funroll-loops' small "empty" loops are already
- removed, so the current behavior is both sub-optimal and
- inconsistent and will change in the future.
-
- * Making side effects happen in the same order as in some other
- compiler.
-
- It is never safe to depend on the order of evaluation of side
- effects. For example, a function call like this may very well
- behave differently from one compiler to another:
-
- void func (int, int);
-
- int i = 2;
- func (i++, i++);
-
- There is no guarantee (in either the C or the C++ standard language
- definitions) that the increments will be evaluated in any
- particular order. Either increment might happen first. `func'
- might get the arguments `2, 3', or it might get `3, 2', or even
- `2, 2'.
-
- * Not allowing structures with volatile fields in registers.
-
- Strictly speaking, there is no prohibition in the ISO C standard
- against allowing structures with volatile fields in registers, but
- it does not seem to make any sense and is probably not what you
- wanted to do. So the compiler will give an error message in this
- case.
-
- * Making certain warnings into errors by default.
-
- Some ISO C testsuites report failure when the compiler does not
- produce an error message for a certain program.
-
- ISO C requires a "diagnostic" message for certain kinds of invalid
- programs, but a warning is defined by GCC to count as a
- diagnostic. If GCC produces a warning but not an error, that is
- correct ISO C support. If test suites call this "failure", they
- should be run with the GCC option `-pedantic-errors', which will
- turn these warnings into errors.
-
-
-\1f
-File: gcc.info, Node: Warnings and Errors, Prev: Non-bugs, Up: Trouble
-
-Warning Messages and Error Messages
-===================================
-
- The GNU compiler can produce two kinds of diagnostics: errors and
-warnings. Each kind has a different purpose:
-
- "Errors" report problems that make it impossible to compile your
- program. GCC reports errors with the source file name and line
- number where the problem is apparent.
-
- "Warnings" report other unusual conditions in your code that _may_
- indicate a problem, although compilation can (and does) proceed.
- Warning messages also report the source file name and line number,
- but include the text `warning:' to distinguish them from error
- messages.
-
- Warnings may indicate danger points where you should check to make
-sure that your program really does what you intend; or the use of
-obsolete features; or the use of nonstandard features of GNU C or C++.
-Many warnings are issued only if you ask for them, with one of the `-W'
-options (for instance, `-Wall' requests a variety of useful warnings).
-
- GCC always tries to compile your program if possible; it never
-gratuitously rejects a program whose meaning is clear merely because
-(for instance) it fails to conform to a standard. In some cases,
-however, the C and C++ standards specify that certain extensions are
-forbidden, and a diagnostic _must_ be issued by a conforming compiler.
-The `-pedantic' option tells GCC to issue warnings in such cases;
-`-pedantic-errors' says to make them errors instead. This does not
-mean that _all_ non-ISO constructs get warnings or errors.
-
- *Note Options to Request or Suppress Warnings: Warning Options, for
-more detail on these and related command-line options.
-
-\1f
-File: gcc.info, Node: Bugs, Next: Service, Prev: Trouble, Up: Top
-
-Reporting Bugs
-**************
-
- Your bug reports play an essential role in making GCC reliable.
-
- When you encounter a problem, the first thing to do is to see if it
-is already known. *Note Trouble::. If it isn't known, then you should
-report the problem.
-
- Reporting a bug may help you by bringing a solution to your problem,
-or it may not. (If it does not, look in the service directory; see
-*Note Service::.) In any case, the principal function of a bug report
-is to help the entire community by making the next version of GCC work
-better. Bug reports are your contribution to the maintenance of GCC.
-
- Since the maintainers are very overloaded, we cannot respond to every
-bug report. However, if the bug has not been fixed, we are likely to
-send you a patch and ask you to tell us whether it works.
-
- In order for a bug report to serve its purpose, you must include the
-information that makes for fixing the bug.
-
-* Menu:
-
-* Criteria: Bug Criteria. Have you really found a bug?
-* Where: Bug Lists. Where to send your bug report.
-* Reporting: Bug Reporting. How to report a bug effectively.
-* GNATS: gccbug. You can use a bug reporting tool.
-* Known: Trouble. Known problems.
-* Help: Service. Where to ask for help.
-
-\1f
-File: gcc.info, Node: Bug Criteria, Next: Bug Lists, Up: Bugs
-
-Have You Found a Bug?
-=====================
-
- If you are not sure whether you have found a bug, here are some
-guidelines:
-
- * If the compiler gets a fatal signal, for any input whatever, that
- is a compiler bug. Reliable compilers never crash.
-
- * If the compiler produces invalid assembly code, for any input
- whatever (except an `asm' statement), that is a compiler bug,
- unless the compiler reports errors (not just warnings) which would
- ordinarily prevent the assembler from being run.
-
- * If the compiler produces valid assembly code that does not
- correctly execute the input source code, that is a compiler bug.
-
- However, you must double-check to make sure, because you may have
- run into an incompatibility between GNU C and traditional C (*note
- Incompatibilities::). These incompatibilities might be considered
- bugs, but they are inescapable consequences of valuable features.
-
- Or you may have a program whose behavior is undefined, which
- happened by chance to give the desired results with another C or
- C++ compiler.
-
- For example, in many nonoptimizing compilers, you can write `x;'
- at the end of a function instead of `return x;', with the same
- results. But the value of the function is undefined if `return'
- is omitted; it is not a bug when GCC produces different results.
-
- Problems often result from expressions with two increment
- operators, as in `f (*p++, *p++)'. Your previous compiler might
- have interpreted that expression the way you intended; GCC might
- interpret it another way. Neither compiler is wrong. The bug is
- in your code.
-
- After you have localized the error to a single source line, it
- should be easy to check for these things. If your program is
- correct and well defined, you have found a compiler bug.
-
- * If the compiler produces an error message for valid input, that is
- a compiler bug.
-
- * If the compiler does not produce an error message for invalid
- input, that is a compiler bug. However, you should note that your
- idea of "invalid input" might be my idea of "an extension" or
- "support for traditional practice".
-
- * If you are an experienced user of one of the languages GCC
- supports, your suggestions for improvement of GCC are welcome in
- any case.
-
-\1f
-File: gcc.info, Node: Bug Lists, Next: Bug Reporting, Prev: Bug Criteria, Up: Bugs
-
-Where to Report Bugs
-====================
-
- Send bug reports for the GNU Compiler Collection to
-<gcc-bugs@gcc.gnu.org>. In accordance with the GNU-wide convention, in
-which bug reports for tool "foo" are sent to `bug-foo@gnu.org', the
-address <bug-gcc@gnu.org> may also be used; it will forward to the
-address given above.
-
- Please read `http://gcc.gnu.org/bugs.html' for additional and/or
-more up-to-date bug reporting instructions before you post a bug report.
-
-This is doc/gcc.info, produced by makeinfo version 4.5 from
+This is doc/gcc.info, produced by makeinfo version 4.11 from
doc/gcc.texi.
INFO-DIR-SECTION Programming
funds for GNU development.
\1f
-File: gcc.info, Node: C Dialect Options, Next: C++ Dialect Options, Prev: Invoking G++, Up: Invoking GCC
+File: gcc.info, Node: i386 and x86-64 Options, Next: HPPA Options, Prev: MIPS Options, Up: Submodel Options
+
+3.17.15 Intel 386 and AMD x86-64 Options
+----------------------------------------
+
+These `-m' options are defined for the i386 and x86-64 family of
+computers:
+
+`-mcpu=CPU-TYPE'
+ Tune to CPU-TYPE everything applicable about the generated code,
+ except for the ABI and the set of available instructions. The
+ choices for CPU-TYPE are `i386', `i486', `i586', `i686',
+ `pentium', `pentium-mmx', `pentiumpro', `pentium2', `pentium3',
+ `pentium4', `k6', `k6-2', `k6-3', `athlon', `athlon-tbird',
+ `athlon-4', `athlon-xp' and `athlon-mp'.
+
+ While picking a specific CPU-TYPE will schedule things
+ appropriately for that particular chip, the compiler will not
+ generate any code that does not run on the i386 without the
+ `-march=CPU-TYPE' option being used. `i586' is equivalent to
+ `pentium' and `i686' is equivalent to `pentiumpro'. `k6' and
+ `athlon' are the AMD chips as opposed to the Intel ones.
+
+`-march=CPU-TYPE'
+ Generate instructions for the machine type CPU-TYPE. The choices
+ for CPU-TYPE are the same as for `-mcpu'. Moreover, specifying
+ `-march=CPU-TYPE' implies `-mcpu=CPU-TYPE'.
+
+`-m386'
+`-m486'
+`-mpentium'
+`-mpentiumpro'
+ These options are synonyms for `-mcpu=i386', `-mcpu=i486',
+ `-mcpu=pentium', and `-mcpu=pentiumpro' respectively. These
+ synonyms are deprecated.
+
+`-mfpmath=UNIT'
+ generate floating point arithmetics for selected unit UNIT. the
+ choices for UNIT are:
+
+ `387'
+ Use the standard 387 floating point coprocessor present
+ majority of chips and emulated otherwise. Code compiled with
+ this option will run almost everywhere. The temporary
+ results are computed in 80bit precesion instead of precision
+ specified by the type resulting in slightly different results
+ compared to most of other chips. See `-ffloat-store' for more
+ detailed description.
+
+ This is the default choice for i386 compiler.
+
+ `sse'
+ Use scalar floating point instructions present in the SSE
+ instruction set. This instruction set is supported by
+ Pentium3 and newer chips, in the AMD line by Athlon-4,
+ Athlon-xp and Athlon-mp chips. The earlier version of SSE
+ instruction set supports only single precision arithmetics,
+ thus the double and extended precision arithmetics is still
+ done using 387. Later version, present only in Pentium4 and
+ the future AMD x86-64 chips supports double precision
+ arithmetics too.
+
+ For i387 you need to use `-march=CPU-TYPE', `-msse' or
+ `-msse2' switches to enable SSE extensions and make this
+ option effective. For x86-64 compiler, these extensions are
+ enabled by default.
+
+ The resulting code should be considerably faster in majority
+ of cases and avoid the numerical instability problems of 387
+ code, but may break some existing code that expects
+ temporaries to be 80bit.
+
+ This is the default choice for x86-64 compiler.
+
+ `sse,387'
+ Attempt to utilize both instruction sets at once. This
+ effectivly double the amount of available registers and on
+ chips with separate execution units for 387 and SSE the
+ execution resources too. Use this option with care, as it is
+ still experimental, because gcc register allocator does not
+ model separate functional units well resulting in instable
+ performance.
+
+`-masm=DIALECT'
+ Output asm instructions using selected DIALECT. Supported choices
+ are `intel' or `att' (the default one).
+
+`-mieee-fp'
+`-mno-ieee-fp'
+ Control whether or not the compiler uses IEEE floating point
+ comparisons. These handle correctly the case where the result of a
+ comparison is unordered.
+
+`-msoft-float'
+ Generate output containing library calls for floating point.
+ *Warning:* the requisite libraries are not part of GCC. Normally
+ the facilities of the machine's usual C compiler are used, but
+ this can't be done directly in cross-compilation. You must make
+ your own arrangements to provide suitable library functions for
+ cross-compilation.
+
+ On machines where a function returns floating point results in the
+ 80387 register stack, some floating point opcodes may be emitted
+ even if `-msoft-float' is used.
+
+`-mno-fp-ret-in-387'
+ Do not use the FPU registers for return values of functions.
+
+ The usual calling convention has functions return values of types
+ `float' and `double' in an FPU register, even if there is no FPU.
+ The idea is that the operating system should emulate an FPU.
+
+ The option `-mno-fp-ret-in-387' causes such values to be returned
+ in ordinary CPU registers instead.
+
+`-mno-fancy-math-387'
+ Some 387 emulators do not support the `sin', `cos' and `sqrt'
+ instructions for the 387. Specify this option to avoid generating
+ those instructions. This option is the default on FreeBSD,
+ OpenBSD and NetBSD. This option is overridden when `-march'
+ indicates that the target cpu will always have an FPU and so the
+ instruction will not need emulation. As of revision 2.6.1, these
+ instructions are not generated unless you also use the
+ `-funsafe-math-optimizations' switch.
+
+`-malign-double'
+`-mno-align-double'
+ Control whether GCC aligns `double', `long double', and `long
+ long' variables on a two word boundary or a one word boundary.
+ Aligning `double' variables on a two word boundary will produce
+ code that runs somewhat faster on a `Pentium' at the expense of
+ more memory.
+
+ *Warning:* if you use the `-malign-double' switch, structures
+ containing the above types will be aligned differently than the
+ published application binary interface specifications for the 386
+ and will not be binary compatible with structures in code compiled
+ without that switch.
+
+`-m128bit-long-double'
+ Control the size of `long double' type. i386 application binary
+ interface specify the size to be 12 bytes, while modern
+ architectures (Pentium and newer) prefer `long double' aligned to
+ 8 or 16 byte boundary. This is impossible to reach with 12 byte
+ long doubles in the array accesses.
+
+ *Warning:* if you use the `-m128bit-long-double' switch, the
+ structures and arrays containing `long double' will change their
+ size as well as function calling convention for function taking
+ `long double' will be modified.
+
+`-m96bit-long-double'
+ Set the size of `long double' to 96 bits as required by the i386
+ application binary interface. This is the default.
+
+`-msvr3-shlib'
+`-mno-svr3-shlib'
+ Control whether GCC places uninitialized local variables into the
+ `bss' or `data' segments. `-msvr3-shlib' places them into `bss'.
+ These options are meaningful only on System V Release 3.
+
+`-mrtd'
+ Use a different function-calling convention, in which functions
+ that take a fixed number of arguments return with the `ret' NUM
+ instruction, which pops their arguments while returning. This
+ saves one instruction in the caller since there is no need to pop
+ the arguments there.
+
+ You can specify that an individual function is called with this
+ calling sequence with the function attribute `stdcall'. You can
+ also override the `-mrtd' option by using the function attribute
+ `cdecl'. *Note Function Attributes::.
+
+ *Warning:* this calling convention is incompatible with the one
+ normally used on Unix, so you cannot use it if you need to call
+ libraries compiled with the Unix compiler.
+
+ Also, you must provide function prototypes for all functions that
+ take variable numbers of arguments (including `printf'); otherwise
+ incorrect code will be generated for calls to those functions.
+
+ In addition, seriously incorrect code will result if you call a
+ function with too many arguments. (Normally, extra arguments are
+ harmlessly ignored.)
+
+`-mregparm=NUM'
+ Control how many registers are used to pass integer arguments. By
+ default, no registers are used to pass arguments, and at most 3
+ registers can be used. You can control this behavior for a
+ specific function by using the function attribute `regparm'.
+ *Note Function Attributes::.
+
+ *Warning:* if you use this switch, and NUM is nonzero, then you
+ must build all modules with the same value, including any
+ libraries. This includes the system libraries and startup modules.
+
+`-mpreferred-stack-boundary=NUM'
+ Attempt to keep the stack boundary aligned to a 2 raised to NUM
+ byte boundary. If `-mpreferred-stack-boundary' is not specified,
+ the default is 4 (16 bytes or 128 bits), except when optimizing
+ for code size (`-Os'), in which case the default is the minimum
+ correct alignment (4 bytes for x86, and 8 bytes for x86-64).
+
+ On Pentium and PentiumPro, `double' and `long double' values
+ should be aligned to an 8 byte boundary (see `-malign-double') or
+ suffer significant run time performance penalties. On Pentium
+ III, the Streaming SIMD Extension (SSE) data type `__m128' suffers
+ similar penalties if it is not 16 byte aligned.
+
+ To ensure proper alignment of this values on the stack, the stack
+ boundary must be as aligned as that required by any value stored
+ on the stack. Further, every function must be generated such that
+ it keeps the stack aligned. Thus calling a function compiled with
+ a higher preferred stack boundary from a function compiled with a
+ lower preferred stack boundary will most likely misalign the
+ stack. It is recommended that libraries that use callbacks always
+ use the default setting.
+
+ This extra alignment does consume extra stack space, and generally
+ increases code size. Code that is sensitive to stack space usage,
+ such as embedded systems and operating system kernels, may want to
+ reduce the preferred alignment to `-mpreferred-stack-boundary=2'.
+
+`-mmmx'
+`-mno-mmx'
+
+`-msse'
+`-mno-sse'
+
+`-msse2'
+`-mno-sse2'
+
+`-m3dnow'
+`-mno-3dnow'
+ These switches enable or disable the use of built-in functions
+ that allow direct access to the MMX, SSE and 3Dnow extensions of
+ the instruction set.
+
+ *Note X86 Built-in Functions::, for details of the functions
+ enabled and disabled by these switches.
+
+ To have SSE/SSE2 instructions generated automatically from
+ floating-point code, see `-mfpmath=sse'.
+
+`-mpush-args'
+`-mno-push-args'
+ Use PUSH operations to store outgoing parameters. This method is
+ shorter and usually equally fast as method using SUB/MOV
+ operations and is enabled by default. In some cases disabling it
+ may improve performance because of improved scheduling and reduced
+ dependencies.
+
+`-maccumulate-outgoing-args'
+ If enabled, the maximum amount of space required for outgoing
+ arguments will be computed in the function prologue. This is
+ faster on most modern CPUs because of reduced dependencies,
+ improved scheduling and reduced stack usage when preferred stack
+ boundary is not equal to 2. The drawback is a notable increase in
+ code size. This switch implies `-mno-push-args'.
+
+`-mthreads'
+ Support thread-safe exception handling on `Mingw32'. Code that
+ relies on thread-safe exception handling must compile and link all
+ code with the `-mthreads' option. When compiling, `-mthreads'
+ defines `-D_MT'; when linking, it links in a special thread helper
+ library `-lmingwthrd' which cleans up per thread exception
+ handling data.
+
+`-mno-align-stringops'
+ Do not align destination of inlined string operations. This
+ switch reduces code size and improves performance in case the
+ destination is already aligned, but gcc don't know about it.
+
+`-minline-all-stringops'
+ By default GCC inlines string operations only when destination is
+ known to be aligned at least to 4 byte boundary. This enables
+ more inlining, increase code size, but may improve performance of
+ code that depends on fast memcpy, strlen and memset for short
+ lengths.
+
+`-momit-leaf-frame-pointer'
+ Don't keep the frame pointer in a register for leaf functions.
+ This avoids the instructions to save, set up and restore frame
+ pointers and makes an extra register available in leaf functions.
+ The option `-fomit-frame-pointer' removes the frame pointer for
+ all functions which might make debugging harder.
+
+ These `-m' switches are supported in addition to the above on AMD
+x86-64 processors in 64-bit environments.
+
+`-m32'
+`-m64'
+ Generate code for a 32-bit or 64-bit environment. The 32-bit
+ environment sets int, long and pointer to 32 bits and generates
+ code that runs on any i386 system. The 64-bit environment sets
+ int to 32 bits and long and pointer to 64 bits and generates code
+ for AMD's x86-64 architecture.
+
+`-mno-red-zone'
+ Do not use a so called red zone for x86-64 code. The red zone is
+ mandated by the x86-64 ABI, it is a 128-byte area beyond the
+ location of the stack pointer that will not be modified by signal
+ or interrupt handlers and therefore can be used for temporary data
+ without adjusting the stack pointer. The flag `-mno-red-zone'
+ disables this red zone.
+
+`-mcmodel=small'
+ Generate code for the small code model: the program and its
+ symbols must be linked in the lower 2 GB of the address space.
+ Pointers are 64 bits. Programs can be statically or dynamically
+ linked. This is the default code model.
+
+`-mcmodel=kernel'
+ Generate code for the kernel code model. The kernel runs in the
+ negative 2 GB of the address space. This model has to be used for
+ Linux kernel code.
+
+`-mcmodel=medium'
+ Generate code for the medium model: The program is linked in the
+ lower 2 GB of the address space but symbols can be located
+ anywhere in the address space. Programs can be statically or
+ dynamically linked, but building of shared libraries are not
+ supported with the medium model.
+
+`-mcmodel=large'
+ Generate code for the large model: This model makes no assumptions
+ about addresses and sizes of sections. Currently GCC does not
+ implement this model.
-Options Controlling C Dialect
-=============================
+\1f
+File: gcc.info, Node: HPPA Options, Next: Intel 960 Options, Prev: i386 and x86-64 Options, Up: Submodel Options
+
+3.17.16 HPPA Options
+--------------------
+
+These `-m' options are defined for the HPPA family of computers:
+
+`-march=ARCHITECTURE-TYPE'
+ Generate code for the specified architecture. The choices for
+ ARCHITECTURE-TYPE are `1.0' for PA 1.0, `1.1' for PA 1.1, and
+ `2.0' for PA 2.0 processors. Refer to `/usr/lib/sched.models' on
+ an HP-UX system to determine the proper architecture option for
+ your machine. Code compiled for lower numbered architectures will
+ run on higher numbered architectures, but not the other way around.
+
+ PA 2.0 support currently requires gas snapshot 19990413 or later.
+ The next release of binutils (current is 2.9.1) will probably
+ contain PA 2.0 support.
+
+`-mpa-risc-1-0'
+`-mpa-risc-1-1'
+`-mpa-risc-2-0'
+ Synonyms for `-march=1.0', `-march=1.1', and `-march=2.0'
+ respectively.
+
+`-mbig-switch'
+ Generate code suitable for big switch tables. Use this option
+ only if the assembler/linker complain about out of range branches
+ within a switch table.
+
+`-mjump-in-delay'
+ Fill delay slots of function calls with unconditional jump
+ instructions by modifying the return pointer for the function call
+ to be the target of the conditional jump.
+
+`-mdisable-fpregs'
+ Prevent floating point registers from being used in any manner.
+ This is necessary for compiling kernels which perform lazy context
+ switching of floating point registers. If you use this option and
+ attempt to perform floating point operations, the compiler will
+ abort.
+
+`-mdisable-indexing'
+ Prevent the compiler from using indexing address modes. This
+ avoids some rather obscure problems when compiling MIG generated
+ code under MACH.
+
+`-mno-space-regs'
+ Generate code that assumes the target has no space registers.
+ This allows GCC to generate faster indirect calls and use unscaled
+ index address modes.
+
+ Such code is suitable for level 0 PA systems and kernels.
+
+`-mfast-indirect-calls'
+ Generate code that assumes calls never cross space boundaries.
+ This allows GCC to emit code which performs faster indirect calls.
+
+ This option will not work in the presence of shared libraries or
+ nested functions.
+
+`-mlong-load-store'
+ Generate 3-instruction load and store sequences as sometimes
+ required by the HP-UX 10 linker. This is equivalent to the `+k'
+ option to the HP compilers.
+
+`-mportable-runtime'
+ Use the portable calling conventions proposed by HP for ELF
+ systems.
+
+`-mgas'
+ Enable the use of assembler directives only GAS understands.
+
+`-mschedule=CPU-TYPE'
+ Schedule code according to the constraints for the machine type
+ CPU-TYPE. The choices for CPU-TYPE are `700' `7100', `7100LC',
+ `7200', and `8000'. Refer to `/usr/lib/sched.models' on an HP-UX
+ system to determine the proper scheduling option for your machine.
+
+`-mlinker-opt'
+ Enable the optimization pass in the HPUX linker. Note this makes
+ symbolic debugging impossible. It also triggers a bug in the HPUX
+ 8 and HPUX 9 linkers in which they give bogus error messages when
+ linking some programs.
+
+`-msoft-float'
+ Generate output containing library calls for floating point.
+ *Warning:* the requisite libraries are not available for all HPPA
+ targets. Normally the facilities of the machine's usual C
+ compiler are used, but this cannot be done directly in
+ cross-compilation. You must make your own arrangements to provide
+ suitable library functions for cross-compilation. The embedded
+ target `hppa1.1-*-pro' does provide software floating point
+ support.
+
+ `-msoft-float' changes the calling convention in the output file;
+ therefore, it is only useful if you compile _all_ of a program with
+ this option. In particular, you need to compile `libgcc.a', the
+ library that comes with GCC, with `-msoft-float' in order for this
+ to work.
+
+\1f
+File: gcc.info, Node: Intel 960 Options, Next: DEC Alpha Options, Prev: HPPA Options, Up: Submodel Options
+
+3.17.17 Intel 960 Options
+-------------------------
+
+These `-m' options are defined for the Intel 960 implementations:
+
+`-mCPU-TYPE'
+ Assume the defaults for the machine type CPU-TYPE for some of the
+ other options, including instruction scheduling, floating point
+ support, and addressing modes. The choices for CPU-TYPE are `ka',
+ `kb', `mc', `ca', `cf', `sa', and `sb'. The default is `kb'.
+
+`-mnumerics'
+`-msoft-float'
+ The `-mnumerics' option indicates that the processor does support
+ floating-point instructions. The `-msoft-float' option indicates
+ that floating-point support should not be assumed.
+
+`-mleaf-procedures'
+`-mno-leaf-procedures'
+ Do (or do not) attempt to alter leaf procedures to be callable
+ with the `bal' instruction as well as `call'. This will result in
+ more efficient code for explicit calls when the `bal' instruction
+ can be substituted by the assembler or linker, but less efficient
+ code in other cases, such as calls via function pointers, or using
+ a linker that doesn't support this optimization.
+
+`-mtail-call'
+`-mno-tail-call'
+ Do (or do not) make additional attempts (beyond those of the
+ machine-independent portions of the compiler) to optimize
+ tail-recursive calls into branches. You may not want to do this
+ because the detection of cases where this is not valid is not
+ totally complete. The default is `-mno-tail-call'.
+
+`-mcomplex-addr'
+`-mno-complex-addr'
+ Assume (or do not assume) that the use of a complex addressing
+ mode is a win on this implementation of the i960. Complex
+ addressing modes may not be worthwhile on the K-series, but they
+ definitely are on the C-series. The default is currently
+ `-mcomplex-addr' for all processors except the CB and CC.
+
+`-mcode-align'
+`-mno-code-align'
+ Align code to 8-byte boundaries for faster fetching (or don't
+ bother). Currently turned on by default for C-series
+ implementations only.
+
+`-mic-compat'
+`-mic2.0-compat'
+`-mic3.0-compat'
+ Enable compatibility with iC960 v2.0 or v3.0.
+
+`-masm-compat'
+`-mintel-asm'
+ Enable compatibility with the iC960 assembler.
+
+`-mstrict-align'
+`-mno-strict-align'
+ Do not permit (do permit) unaligned accesses.
+
+`-mold-align'
+ Enable structure-alignment compatibility with Intel's gcc release
+ version 1.3 (based on gcc 1.37). This option implies
+ `-mstrict-align'.
+
+`-mlong-double-64'
+ Implement type `long double' as 64-bit floating point numbers.
+ Without the option `long double' is implemented by 80-bit floating
+ point numbers. The only reason we have it because there is no
+ 128-bit `long double' support in `fp-bit.c' yet. So it is only
+ useful for people using soft-float targets. Otherwise, we should
+ recommend against use of it.
+
+
+\1f
+File: gcc.info, Node: DEC Alpha Options, Next: DEC Alpha/VMS Options, Prev: Intel 960 Options, Up: Submodel Options
+
+3.17.18 DEC Alpha Options
+-------------------------
+
+These `-m' options are defined for the DEC Alpha implementations:
+
+`-mno-soft-float'
+`-msoft-float'
+ Use (do not use) the hardware floating-point instructions for
+ floating-point operations. When `-msoft-float' is specified,
+ functions in `libgcc.a' will be used to perform floating-point
+ operations. Unless they are replaced by routines that emulate the
+ floating-point operations, or compiled in such a way as to call
+ such emulations routines, these routines will issue floating-point
+ operations. If you are compiling for an Alpha without
+ floating-point operations, you must ensure that the library is
+ built so as not to call them.
+
+ Note that Alpha implementations without floating-point operations
+ are required to have floating-point registers.
+
+`-mfp-reg'
+`-mno-fp-regs'
+ Generate code that uses (does not use) the floating-point register
+ set. `-mno-fp-regs' implies `-msoft-float'. If the floating-point
+ register set is not used, floating point operands are passed in
+ integer registers as if they were integers and floating-point
+ results are passed in `$0' instead of `$f0'. This is a
+ non-standard calling sequence, so any function with a
+ floating-point argument or return value called by code compiled
+ with `-mno-fp-regs' must also be compiled with that option.
+
+ A typical use of this option is building a kernel that does not
+ use, and hence need not save and restore, any floating-point
+ registers.
+
+`-mieee'
+ The Alpha architecture implements floating-point hardware
+ optimized for maximum performance. It is mostly compliant with
+ the IEEE floating point standard. However, for full compliance,
+ software assistance is required. This option generates code fully
+ IEEE compliant code _except_ that the INEXACT-FLAG is not
+ maintained (see below). If this option is turned on, the
+ preprocessor macro `_IEEE_FP' is defined during compilation. The
+ resulting code is less efficient but is able to correctly support
+ denormalized numbers and exceptional IEEE values such as
+ not-a-number and plus/minus infinity. Other Alpha compilers call
+ this option `-ieee_with_no_inexact'.
+
+`-mieee-with-inexact'
+ This is like `-mieee' except the generated code also maintains the
+ IEEE INEXACT-FLAG. Turning on this option causes the generated
+ code to implement fully-compliant IEEE math. In addition to
+ `_IEEE_FP', `_IEEE_FP_EXACT' is defined as a preprocessor macro.
+ On some Alpha implementations the resulting code may execute
+ significantly slower than the code generated by default. Since
+ there is very little code that depends on the INEXACT-FLAG, you
+ should normally not specify this option. Other Alpha compilers
+ call this option `-ieee_with_inexact'.
+
+`-mfp-trap-mode=TRAP-MODE'
+ This option controls what floating-point related traps are enabled.
+ Other Alpha compilers call this option `-fptm TRAP-MODE'. The
+ trap mode can be set to one of four values:
+
+ `n'
+ This is the default (normal) setting. The only traps that
+ are enabled are the ones that cannot be disabled in software
+ (e.g., division by zero trap).
+
+ `u'
+ In addition to the traps enabled by `n', underflow traps are
+ enabled as well.
+
+ `su'
+ Like `su', but the instructions are marked to be safe for
+ software completion (see Alpha architecture manual for
+ details).
+
+ `sui'
+ Like `su', but inexact traps are enabled as well.
+
+`-mfp-rounding-mode=ROUNDING-MODE'
+ Selects the IEEE rounding mode. Other Alpha compilers call this
+ option `-fprm ROUNDING-MODE'. The ROUNDING-MODE can be one of:
+
+ `n'
+ Normal IEEE rounding mode. Floating point numbers are
+ rounded towards the nearest machine number or towards the
+ even machine number in case of a tie.
+
+ `m'
+ Round towards minus infinity.
+
+ `c'
+ Chopped rounding mode. Floating point numbers are rounded
+ towards zero.
+
+ `d'
+ Dynamic rounding mode. A field in the floating point control
+ register (FPCR, see Alpha architecture reference manual)
+ controls the rounding mode in effect. The C library
+ initializes this register for rounding towards plus infinity.
+ Thus, unless your program modifies the FPCR, `d' corresponds
+ to round towards plus infinity.
+
+`-mtrap-precision=TRAP-PRECISION'
+ In the Alpha architecture, floating point traps are imprecise.
+ This means without software assistance it is impossible to recover
+ from a floating trap and program execution normally needs to be
+ terminated. GCC can generate code that can assist operating
+ system trap handlers in determining the exact location that caused
+ a floating point trap. Depending on the requirements of an
+ application, different levels of precisions can be selected:
+
+ `p'
+ Program precision. This option is the default and means a
+ trap handler can only identify which program caused a
+ floating point exception.
+
+ `f'
+ Function precision. The trap handler can determine the
+ function that caused a floating point exception.
+
+ `i'
+ Instruction precision. The trap handler can determine the
+ exact instruction that caused a floating point exception.
+
+ Other Alpha compilers provide the equivalent options called
+ `-scope_safe' and `-resumption_safe'.
+
+`-mieee-conformant'
+ This option marks the generated code as IEEE conformant. You must
+ not use this option unless you also specify `-mtrap-precision=i'
+ and either `-mfp-trap-mode=su' or `-mfp-trap-mode=sui'. Its only
+ effect is to emit the line `.eflag 48' in the function prologue of
+ the generated assembly file. Under DEC Unix, this has the effect
+ that IEEE-conformant math library routines will be linked in.
+
+`-mbuild-constants'
+ Normally GCC examines a 32- or 64-bit integer constant to see if
+ it can construct it from smaller constants in two or three
+ instructions. If it cannot, it will output the constant as a
+ literal and generate code to load it from the data segment at
+ runtime.
+
+ Use this option to require GCC to construct _all_ integer constants
+ using code, even if it takes more instructions (the maximum is
+ six).
+
+ You would typically use this option to build a shared library
+ dynamic loader. Itself a shared library, it must relocate itself
+ in memory before it can find the variables and constants in its
+ own data segment.
+
+`-malpha-as'
+`-mgas'
+ Select whether to generate code to be assembled by the
+ vendor-supplied assembler (`-malpha-as') or by the GNU assembler
+ `-mgas'.
+
+`-mbwx'
+`-mno-bwx'
+`-mcix'
+`-mno-cix'
+`-mfix'
+`-mno-fix'
+`-mmax'
+`-mno-max'
+ Indicate whether GCC should generate code to use the optional BWX,
+ CIX, FIX and MAX instruction sets. The default is to use the
+ instruction sets supported by the CPU type specified via `-mcpu='
+ option or that of the CPU on which GCC was built if none was
+ specified.
+
+`-mfloat-vax'
+`-mfloat-ieee'
+ Generate code that uses (does not use) VAX F and G floating point
+ arithmetic instead of IEEE single and double precision.
+
+`-mexplicit-relocs'
+`-mno-explicit-relocs'
+ Older Alpha assemblers provided no way to generate symbol
+ relocations except via assembler macros. Use of these macros does
+ not allow optimial instruction scheduling. GNU binutils as of
+ version 2.12 supports a new syntax that allows the compiler to
+ explicitly mark which relocations should apply to which
+ instructions. This option is mostly useful for debugging, as GCC
+ detects the capabilities of the assembler when it is built and
+ sets the default accordingly.
+
+`-msmall-data'
+`-mlarge-data'
+ When `-mexplicit-relocs' is in effect, static data is accessed via
+ "gp-relative" relocations. When `-msmall-data' is used, objects 8
+ bytes long or smaller are placed in a "small data area" (the
+ `.sdata' and `.sbss' sections) and are accessed via 16-bit
+ relocations off of the `$gp' register. This limits the size of
+ the small data area to 64KB, but allows the variables to be
+ directly accessed via a single instruction.
+
+ The default is `-mlarge-data'. With this option the data area is
+ limited to just below 2GB. Programs that require more than 2GB of
+ data must use `malloc' or `mmap' to allocate the data in the heap
+ instead of in the program's data segment.
+
+ When generating code for shared libraries, `-fpic' implies
+ `-msmall-data' and `-fPIC' implies `-mlarge-data'.
+
+`-mcpu=CPU_TYPE'
+ Set the instruction set and instruction scheduling parameters for
+ machine type CPU_TYPE. You can specify either the `EV' style name
+ or the corresponding chip number. GCC supports scheduling
+ parameters for the EV4, EV5 and EV6 family of processors and will
+ choose the default values for the instruction set from the
+ processor you specify. If you do not specify a processor type,
+ GCC will default to the processor on which the compiler was built.
+
+ Supported values for CPU_TYPE are
+
+ `ev4'
+
+ `ev45'
+ `21064'
+ Schedules as an EV4 and has no instruction set extensions.
+
+ `ev5'
+ `21164'
+ Schedules as an EV5 and has no instruction set extensions.
+
+ `ev56'
+ `21164a'
+ Schedules as an EV5 and supports the BWX extension.
+
+ `pca56'
+ `21164pc'
+ `21164PC'
+ Schedules as an EV5 and supports the BWX and MAX extensions.
+
+ `ev6'
+ `21264'
+ Schedules as an EV6 and supports the BWX, FIX, and MAX
+ extensions.
+
+ `ev67'
+
+ `21264a'
+ Schedules as an EV6 and supports the BWX, CIX, FIX, and MAX
+ extensions.
+
+`-mtune=CPU_TYPE'
+ Set only the instruction scheduling parameters for machine type
+ CPU_TYPE. The instruction set is not changed.
+
+`-mmemory-latency=TIME'
+ Sets the latency the scheduler should assume for typical memory
+ references as seen by the application. This number is highly
+ dependent on the memory access patterns used by the application
+ and the size of the external cache on the machine.
+
+ Valid options for TIME are
+
+ `NUMBER'
+ A decimal number representing clock cycles.
+
+ `L1'
+ `L2'
+ `L3'
+ `main'
+ The compiler contains estimates of the number of clock cycles
+ for "typical" EV4 & EV5 hardware for the Level 1, 2 & 3 caches
+ (also called Dcache, Scache, and Bcache), as well as to main
+ memory. Note that L3 is only valid for EV5.
+
+
+\1f
+File: gcc.info, Node: DEC Alpha/VMS Options, Next: Clipper Options, Prev: DEC Alpha Options, Up: Submodel Options
+
+3.17.19 DEC Alpha/VMS Options
+-----------------------------
+
+These `-m' options are defined for the DEC Alpha/VMS implementations:
+
+`-mvms-return-codes'
+ Return VMS condition codes from main. The default is to return
+ POSIX style condition (e.g. error) codes.
+
+\1f
+File: gcc.info, Node: Clipper Options, Next: H8/300 Options, Prev: DEC Alpha/VMS Options, Up: Submodel Options
+
+3.17.20 Clipper Options
+-----------------------
+
+These `-m' options are defined for the Clipper implementations:
+
+`-mc300'
+ Produce code for a C300 Clipper processor. This is the default.
+
+`-mc400'
+ Produce code for a C400 Clipper processor, i.e. use floating point
+ registers f8-f15.
+
+\1f
+File: gcc.info, Node: H8/300 Options, Next: SH Options, Prev: Clipper Options, Up: Submodel Options
+
+3.17.21 H8/300 Options
+----------------------
+
+These `-m' options are defined for the H8/300 implementations:
+
+`-mrelax'
+ Shorten some address references at link time, when possible; uses
+ the linker option `-relax'. *Note `ld' and the H8/300:
+ (ld.info)H8/300, for a fuller description.
+
+`-mh'
+ Generate code for the H8/300H.
+
+`-ms'
+ Generate code for the H8/S.
+
+`-ms2600'
+ Generate code for the H8/S2600. This switch must be used with
+ `-ms'.
+
+`-mint32'
+ Make `int' data 32 bits by default.
+
+`-malign-300'
+ On the H8/300H and H8/S, use the same alignment rules as for the
+ H8/300. The default for the H8/300H and H8/S is to align longs
+ and floats on 4 byte boundaries. `-malign-300' causes them to be
+ aligned on 2 byte boundaries. This option has no effect on the
+ H8/300.
+
+\1f
+File: gcc.info, Node: SH Options, Next: System V Options, Prev: H8/300 Options, Up: Submodel Options
+
+3.17.22 SH Options
+------------------
+
+These `-m' options are defined for the SH implementations:
+
+`-m1'
+ Generate code for the SH1.
+
+`-m2'
+ Generate code for the SH2.
+
+`-m3'
+ Generate code for the SH3.
+
+`-m3e'
+ Generate code for the SH3e.
+
+`-m4-nofpu'
+ Generate code for the SH4 without a floating-point unit.
+
+`-m4-single-only'
+ Generate code for the SH4 with a floating-point unit that only
+ supports single-precision arithmetic.
+
+`-m4-single'
+ Generate code for the SH4 assuming the floating-point unit is in
+ single-precision mode by default.
+
+`-m4'
+ Generate code for the SH4.
+
+`-mb'
+ Compile code for the processor in big endian mode.
+
+`-ml'
+ Compile code for the processor in little endian mode.
+
+`-mdalign'
+ Align doubles at 64-bit boundaries. Note that this changes the
+ calling conventions, and thus some functions from the standard C
+ library will not work unless you recompile it first with
+ `-mdalign'.
+
+`-mrelax'
+ Shorten some address references at link time, when possible; uses
+ the linker option `-relax'.
+
+`-mbigtable'
+ Use 32-bit offsets in `switch' tables. The default is to use
+ 16-bit offsets.
+
+`-mfmovd'
+ Enable the use of the instruction `fmovd'.
+
+`-mhitachi'
+ Comply with the calling conventions defined by Hitachi.
+
+`-mnomacsave'
+ Mark the `MAC' register as call-clobbered, even if `-mhitachi' is
+ given.
+
+`-mieee'
+ Increase IEEE-compliance of floating-point code.
+
+`-misize'
+ Dump instruction size and location in the assembly code.
+
+`-mpadstruct'
+ This option is deprecated. It pads structures to multiple of 4
+ bytes, which is incompatible with the SH ABI.
+
+`-mspace'
+ Optimize for space instead of speed. Implied by `-Os'.
+
+`-mprefergot'
+ When generating position-independent code, emit function calls
+ using the Global Offset Table instead of the Procedure Linkage
+ Table.
+
+`-musermode'
+ Generate a library function call to invalidate instruction cache
+ entries, after fixing up a trampoline. This library function call
+ doesn't assume it can write to the whole memory address space.
+ This is the default when the target is `sh-*-linux*'.
+
+\1f
+File: gcc.info, Node: System V Options, Next: TMS320C3x/C4x Options, Prev: SH Options, Up: Submodel Options
+
+3.17.23 Options for System V
+----------------------------
+
+These additional options are available on System V Release 4 for
+compatibility with other compilers on those systems:
+
+`-G'
+ Create a shared object. It is recommended that `-symbolic' or
+ `-shared' be used instead.
+
+`-Qy'
+ Identify the versions of each tool used by the compiler, in a
+ `.ident' assembler directive in the output.
+
+`-Qn'
+ Refrain from adding `.ident' directives to the output file (this is
+ the default).
+
+`-YP,DIRS'
+ Search the directories DIRS, and no others, for libraries
+ specified with `-l'.
+
+`-Ym,DIR'
+ Look in the directory DIR to find the M4 preprocessor. The
+ assembler uses this option.
- The following options control the dialect of C (or languages derived
-from C, such as C++ and Objective-C) that the compiler accepts:
-
-`-ansi'
- In C mode, support all ISO C89 programs. In C++ mode, remove GNU
- extensions that conflict with ISO C++.
-
- This turns off certain features of GCC that are incompatible with
- ISO C89 (when compiling C code), or of standard C++ (when
- compiling C++ code), such as the `asm' and `typeof' keywords, and
- predefined macros such as `unix' and `vax' that identify the type
- of system you are using. It also enables the undesirable and
- rarely used ISO trigraph feature. For the C compiler, it disables
- recognition of C++ style `//' comments as well as the `inline'
- keyword.
-
- The alternate keywords `__asm__', `__extension__', `__inline__'
- and `__typeof__' continue to work despite `-ansi'. You would not
- want to use them in an ISO C program, of course, but it is useful
- to put them in header files that might be included in compilations
- done with `-ansi'. Alternate predefined macros such as `__unix__'
- and `__vax__' are also available, with or without `-ansi'.
-
- The `-ansi' option does not cause non-ISO programs to be rejected
- gratuitously. For that, `-pedantic' is required in addition to
- `-ansi'. *Note Warning Options::.
-
- The macro `__STRICT_ANSI__' is predefined when the `-ansi' option
- is used. Some header files may notice this macro and refrain from
- declaring certain functions or defining certain macros that the
- ISO standard doesn't call for; this is to avoid interfering with
- any programs that might use these names for other things.
-
- Functions which would normally be built in but do not have
- semantics defined by ISO C (such as `alloca' and `ffs') are not
- built-in functions with `-ansi' is used. *Note Other built-in
- functions provided by GCC: Other Builtins, for details of the
- functions affected.
-
-`-std='
- Determine the language standard. This option is currently only
- supported when compiling C. A value for this option must be
- provided; possible values are
-
- `c89'
- `iso9899:1990'
- ISO C89 (same as `-ansi').
-
- `iso9899:199409'
- ISO C89 as modified in amendment 1.
-
- `c99'
- `c9x'
- `iso9899:1999'
- `iso9899:199x'
- ISO C99. Note that this standard is not yet fully supported;
- see `http://gcc.gnu.org/gcc-3.1/c99status.html' for more
- information. The names `c9x' and `iso9899:199x' are
- deprecated.
-
- `gnu89'
- Default, ISO C89 plus GNU extensions (including some C99
- features).
-
- `gnu99'
-
- `gnu9x'
- ISO C99 plus GNU extensions. When ISO C99 is fully
- implemented in GCC, this will become the default. The name
- `gnu9x' is deprecated.
-
-
- Even when this option is not specified, you can still use some of
- the features of newer standards in so far as they do not conflict
- with previous C standards. For example, you may use
- `__restrict__' even when `-std=c99' is not specified.
-
- The `-std' options specifying some version of ISO C have the same
- effects as `-ansi', except that features that were not in ISO C89
- but are in the specified version (for example, `//' comments and
- the `inline' keyword in ISO C99) are not disabled.
-
- *Note Language Standards Supported by GCC: Standards, for details
- of these standard versions.
-
-`-aux-info FILENAME'
- Output to the given filename prototyped declarations for all
- functions declared and/or defined in a translation unit, including
- those in header files. This option is silently ignored in any
- language other than C.
-
- Besides declarations, the file indicates, in comments, the origin
- of each declaration (source file and line), whether the
- declaration was implicit, prototyped or unprototyped (`I', `N' for
- new or `O' for old, respectively, in the first character after the
- line number and the colon), and whether it came from a declaration
- or a definition (`C' or `F', respectively, in the following
- character). In the case of function definitions, a K&R-style list
- of arguments followed by their declarations is also provided,
- inside comments, after the declaration.
-
-`-fno-asm'
- Do not recognize `asm', `inline' or `typeof' as a keyword, so that
- code can use these words as identifiers. You can use the keywords
- `__asm__', `__inline__' and `__typeof__' instead. `-ansi' implies
- `-fno-asm'.
-
- In C++, this switch only affects the `typeof' keyword, since `asm'
- and `inline' are standard keywords. You may want to use the
- `-fno-gnu-keywords' flag instead, which has the same effect. In
- C99 mode (`-std=c99' or `-std=gnu99'), this switch only affects
- the `asm' and `typeof' keywords, since `inline' is a standard
- keyword in ISO C99.
-
-`-fno-builtin'
-`-fno-builtin-FUNCTION (C and Objective-C only)'
- Don't recognize built-in functions that do not begin with
- `__builtin_' as prefix. *Note Other built-in functions provided
- by GCC: Other Builtins, for details of the functions affected,
- including those which are not built-in functions when `-ansi' or
- `-std' options for strict ISO C conformance are used because they
- do not have an ISO standard meaning.
-
- GCC normally generates special code to handle certain built-in
- functions more efficiently; for instance, calls to `alloca' may
- become single instructions that adjust the stack directly, and
- calls to `memcpy' may become inline copy loops. The resulting
- code is often both smaller and faster, but since the function
- calls no longer appear as such, you cannot set a breakpoint on
- those calls, nor can you change the behavior of the functions by
- linking with a different library.
-
- In C++, `-fno-builtin' is always in effect. The `-fbuiltin'
- option has no effect. Therefore, in C++, the only way to get the
- optimization benefits of built-in functions is to call the function
- using the `__builtin_' prefix. The GNU C++ Standard Library uses
- built-in functions to implement many functions (like
- `std::strchr'), so that you automatically get efficient code.
-
- With the `-fno-builtin-FUNCTION' option, not available when
- compiling C++, only the built-in function FUNCTION is disabled.
- FUNCTION must not begin with `__builtin_'. If a function is named
- this is not built-in in this version of GCC, this option is
- ignored. There is no corresponding `-fbuiltin-FUNCTION' option;
- if you wish to enable built-in functions selectively when using
- `-fno-builtin' or `-ffreestanding', you may define macros such as:
-
- #define abs(n) __builtin_abs ((n))
- #define strcpy(d, s) __builtin_strcpy ((d), (s))
-
-`-fhosted'
- Assert that compilation takes place in a hosted environment. This
- implies `-fbuiltin'. A hosted environment is one in which the
- entire standard library is available, and in which `main' has a
- return type of `int'. Examples are nearly everything except a
- kernel. This is equivalent to `-fno-freestanding'.
-
-`-ffreestanding'
- Assert that compilation takes place in a freestanding environment.
- This implies `-fno-builtin'. A freestanding environment is one
- in which the standard library may not exist, and program startup
- may not necessarily be at `main'. The most obvious example is an
- OS kernel. This is equivalent to `-fno-hosted'.
-
- *Note Language Standards Supported by GCC: Standards, for details
- of freestanding and hosted environments.
-
-`-trigraphs'
- Support ISO C trigraphs. The `-ansi' option (and `-std' options
- for strict ISO C conformance) implies `-trigraphs'.
-
-`-no-integrated-cpp'
- Invoke the external cpp during compilation. The default is to use
- the integrated cpp (internal cpp). This option also allows a
- user-supplied cpp via the `-B' option. This flag is applicable in
- both C and C++ modes.
-
- We do not guarantee to retain this option in future, and we may
- change its semantics.
-
-`-traditional'
- Attempt to support some aspects of traditional C compilers.
- Specifically:
-
- * All `extern' declarations take effect globally even if they
- are written inside of a function definition. This includes
- implicit declarations of functions.
-
- * The newer keywords `typeof', `inline', `signed', `const' and
- `volatile' are not recognized. (You can still use the
- alternative keywords such as `__typeof__', `__inline__', and
- so on.)
-
- * Comparisons between pointers and integers are always allowed.
-
- * Integer types `unsigned short' and `unsigned char' promote to
- `unsigned int'.
-
- * Out-of-range floating point literals are not an error.
-
- * Certain constructs which ISO regards as a single invalid
- preprocessing number, such as `0xe-0xd', are treated as
- expressions instead.
-
- * String "constants" are not necessarily constant; they are
- stored in writable space, and identical looking constants are
- allocated separately. (This is the same as the effect of
- `-fwritable-strings'.)
-
- * All automatic variables not declared `register' are preserved
- by `longjmp'. Ordinarily, GNU C follows ISO C: automatic
- variables not declared `volatile' may be clobbered.
-
- * The character escape sequences `\x' and `\a' evaluate as the
- literal characters `x' and `a' respectively. Without
- `-traditional', `\x' is a prefix for the hexadecimal
- representation of a character, and `\a' produces a bell.
-
- This option is deprecated and may be removed.
-
- You may wish to use `-fno-builtin' as well as `-traditional' if
- your program uses names that are normally GNU C built-in functions
- for other purposes of its own.
-
- You cannot use `-traditional' if you include any header files that
- rely on ISO C features. Some vendors are starting to ship systems
- with ISO C header files and you cannot use `-traditional' on such
- systems to compile files that include any system headers.
-
- The `-traditional' option also enables `-traditional-cpp'.
-
-`-traditional-cpp'
- Attempt to support some aspects of traditional C preprocessors.
- See the GNU CPP manual for details.
-
-`-fcond-mismatch'
- Allow conditional expressions with mismatched types in the second
- and third arguments. The value of such an expression is void.
- This option is not supported for C++.
-
-`-funsigned-char'
- Let the type `char' be unsigned, like `unsigned char'.
+\1f
+File: gcc.info, Node: TMS320C3x/C4x Options, Next: V850 Options, Prev: System V Options, Up: Submodel Options
+
+3.17.24 TMS320C3x/C4x Options
+-----------------------------
+
+These `-m' options are defined for TMS320C3x/C4x implementations:
+
+`-mcpu=CPU_TYPE'
+ Set the instruction set, register set, and instruction scheduling
+ parameters for machine type CPU_TYPE. Supported values for
+ CPU_TYPE are `c30', `c31', `c32', `c40', and `c44'. The default
+ is `c40' to generate code for the TMS320C40.
+
+`-mbig-memory'
+
+`-mbig'
+`-msmall-memory'
+`-msmall'
+ Generates code for the big or small memory model. The small memory
+ model assumed that all data fits into one 64K word page. At
+ run-time the data page (DP) register must be set to point to the
+ 64K page containing the .bss and .data program sections. The big
+ memory model is the default and requires reloading of the DP
+ register for every direct memory access.
+
+`-mbk'
+`-mno-bk'
+ Allow (disallow) allocation of general integer operands into the
+ block count register BK.
+
+`-mdb'
+`-mno-db'
+ Enable (disable) generation of code using decrement and branch,
+ DBcond(D), instructions. This is enabled by default for the C4x.
+ To be on the safe side, this is disabled for the C3x, since the
+ maximum iteration count on the C3x is 2^23 + 1 (but who iterates
+ loops more than 2^23 times on the C3x?). Note that GCC will try
+ to reverse a loop so that it can utilise the decrement and branch
+ instruction, but will give up if there is more than one memory
+ reference in the loop. Thus a loop where the loop counter is
+ decremented can generate slightly more efficient code, in cases
+ where the RPTB instruction cannot be utilised.
+
+`-mdp-isr-reload'
+`-mparanoid'
+ Force the DP register to be saved on entry to an interrupt service
+ routine (ISR), reloaded to point to the data section, and restored
+ on exit from the ISR. This should not be required unless someone
+ has violated the small memory model by modifying the DP register,
+ say within an object library.
+
+`-mmpyi'
+`-mno-mpyi'
+ For the C3x use the 24-bit MPYI instruction for integer multiplies
+ instead of a library call to guarantee 32-bit results. Note that
+ if one of the operands is a constant, then the multiplication will
+ be performed using shifts and adds. If the `-mmpyi' option is not
+ specified for the C3x, then squaring operations are performed
+ inline instead of a library call.
+
+`-mfast-fix'
+`-mno-fast-fix'
+ The C3x/C4x FIX instruction to convert a floating point value to an
+ integer value chooses the nearest integer less than or equal to the
+ floating point value rather than to the nearest integer. Thus if
+ the floating point number is negative, the result will be
+ incorrectly truncated an additional code is necessary to detect
+ and correct this case. This option can be used to disable
+ generation of the additional code required to correct the result.
+
+`-mrptb'
+`-mno-rptb'
+ Enable (disable) generation of repeat block sequences using the
+ RPTB instruction for zero overhead looping. The RPTB construct is
+ only used for innermost loops that do not call functions or jump
+ across the loop boundaries. There is no advantage having nested
+ RPTB loops due to the overhead required to save and restore the
+ RC, RS, and RE registers. This is enabled by default with `-O2'.
+
+`-mrpts=COUNT'
+`-mno-rpts'
+ Enable (disable) the use of the single instruction repeat
+ instruction RPTS. If a repeat block contains a single
+ instruction, and the loop count can be guaranteed to be less than
+ the value COUNT, GCC will emit a RPTS instruction instead of a
+ RPTB. If no value is specified, then a RPTS will be emitted even
+ if the loop count cannot be determined at compile time. Note that
+ the repeated instruction following RPTS does not have to be
+ reloaded from memory each iteration, thus freeing up the CPU buses
+ for operands. However, since interrupts are blocked by this
+ instruction, it is disabled by default.
+
+`-mloop-unsigned'
+`-mno-loop-unsigned'
+ The maximum iteration count when using RPTS and RPTB (and DB on
+ the C40) is 2^31 + 1 since these instructions test if the
+ iteration count is negative to terminate the loop. If the
+ iteration count is unsigned there is a possibility than the 2^31 +
+ 1 maximum iteration count may be exceeded. This switch allows an
+ unsigned iteration count.
+
+`-mti'
+ Try to emit an assembler syntax that the TI assembler (asm30) is
+ happy with. This also enforces compatibility with the API
+ employed by the TI C3x C compiler. For example, long doubles are
+ passed as structures rather than in floating point registers.
+
+`-mregparm'
+`-mmemparm'
+ Generate code that uses registers (stack) for passing arguments to
+ functions. By default, arguments are passed in registers where
+ possible rather than by pushing arguments on to the stack.
+
+`-mparallel-insns'
+`-mno-parallel-insns'
+ Allow the generation of parallel instructions. This is enabled by
+ default with `-O2'.
+
+`-mparallel-mpy'
+`-mno-parallel-mpy'
+ Allow the generation of MPY||ADD and MPY||SUB parallel
+ instructions, provided `-mparallel-insns' is also specified.
+ These instructions have tight register constraints which can
+ pessimize the code generation of large functions.
+
+
+\1f
+File: gcc.info, Node: V850 Options, Next: ARC Options, Prev: TMS320C3x/C4x Options, Up: Submodel Options
+
+3.17.25 V850 Options
+--------------------
+
+These `-m' options are defined for V850 implementations:
+
+`-mlong-calls'
+`-mno-long-calls'
+ Treat all calls as being far away (near). If calls are assumed to
+ be far away, the compiler will always load the functions address
+ up into a register, and call indirect through the pointer.
+
+`-mno-ep'
+`-mep'
+ Do not optimize (do optimize) basic blocks that use the same index
+ pointer 4 or more times to copy pointer into the `ep' register, and
+ use the shorter `sld' and `sst' instructions. The `-mep' option
+ is on by default if you optimize.
+
+`-mno-prolog-function'
+`-mprolog-function'
+ Do not use (do use) external functions to save and restore
+ registers at the prolog and epilog of a function. The external
+ functions are slower, but use less code space if more than one
+ function saves the same number of registers. The
+ `-mprolog-function' option is on by default if you optimize.
+
+`-mspace'
+ Try to make the code as small as possible. At present, this just
+ turns on the `-mep' and `-mprolog-function' options.
+
+`-mtda=N'
+ Put static or global variables whose size is N bytes or less into
+ the tiny data area that register `ep' points to. The tiny data
+ area can hold up to 256 bytes in total (128 bytes for byte
+ references).
+
+`-msda=N'
+ Put static or global variables whose size is N bytes or less into
+ the small data area that register `gp' points to. The small data
+ area can hold up to 64 kilobytes.
+
+`-mzda=N'
+ Put static or global variables whose size is N bytes or less into
+ the first 32 kilobytes of memory.
+
+`-mv850'
+ Specify that the target processor is the V850.
+
+`-mbig-switch'
+ Generate code suitable for big switch tables. Use this option
+ only if the assembler/linker complain about out of range branches
+ within a switch table.
+
+\1f
+File: gcc.info, Node: ARC Options, Next: NS32K Options, Prev: V850 Options, Up: Submodel Options
+
+3.17.26 ARC Options
+-------------------
+
+These options are defined for ARC implementations:
+
+`-EL'
+ Compile code for little endian mode. This is the default.
+
+`-EB'
+ Compile code for big endian mode.
+
+`-mmangle-cpu'
+ Prepend the name of the cpu to all public symbol names. In
+ multiple-processor systems, there are many ARC variants with
+ different instruction and register set characteristics. This flag
+ prevents code compiled for one cpu to be linked with code compiled
+ for another. No facility exists for handling variants that are
+ "almost identical". This is an all or nothing option.
+
+`-mcpu=CPU'
+ Compile code for ARC variant CPU. Which variants are supported
+ depend on the configuration. All variants support `-mcpu=base',
+ this is the default.
+
+`-mtext=TEXT-SECTION'
+`-mdata=DATA-SECTION'
+`-mrodata=READONLY-DATA-SECTION'
+ Put functions, data, and readonly data in TEXT-SECTION,
+ DATA-SECTION, and READONLY-DATA-SECTION respectively by default.
+ This can be overridden with the `section' attribute. *Note
+ Variable Attributes::.
+
+
+\1f
+File: gcc.info, Node: NS32K Options, Next: AVR Options, Prev: ARC Options, Up: Submodel Options
+
+3.17.27 NS32K Options
+---------------------
+
+These are the `-m' options defined for the 32000 series. The default
+values for these options depends on which style of 32000 was selected
+when the compiler was configured; the defaults for the most common
+choices are given below.
+
+`-m32032'
+`-m32032'
+ Generate output for a 32032. This is the default when the
+ compiler is configured for 32032 and 32016 based systems.
+
+`-m32332'
+`-m32332'
+ Generate output for a 32332. This is the default when the
+ compiler is configured for 32332-based systems.
+
+`-m32532'
+`-m32532'
+ Generate output for a 32532. This is the default when the
+ compiler is configured for 32532-based systems.
+
+`-m32081'
+ Generate output containing 32081 instructions for floating point.
+ This is the default for all systems.
+
+`-m32381'
+ Generate output containing 32381 instructions for floating point.
+ This also implies `-m32081'. The 32381 is only compatible with
+ the 32332 and 32532 cpus. This is the default for the
+ pc532-netbsd configuration.
+
+`-mmulti-add'
+ Try and generate multiply-add floating point instructions `polyF'
+ and `dotF'. This option is only available if the `-m32381' option
+ is in effect. Using these instructions requires changes to
+ register allocation which generally has a negative impact on
+ performance. This option should only be enabled when compiling
+ code particularly likely to make heavy use of multiply-add
+ instructions.
+
+`-mnomulti-add'
+ Do not try and generate multiply-add floating point instructions
+ `polyF' and `dotF'. This is the default on all platforms.
+
+`-msoft-float'
+ Generate output containing library calls for floating point.
+ *Warning:* the requisite libraries may not be available.
+
+`-mnobitfield'
+ Do not use the bit-field instructions. On some machines it is
+ faster to use shifting and masking operations. This is the
+ default for the pc532.
+
+`-mbitfield'
+ Do use the bit-field instructions. This is the default for all
+ platforms except the pc532.
+
+`-mrtd'
+ Use a different function-calling convention, in which functions
+ that take a fixed number of arguments return pop their arguments
+ on return with the `ret' instruction.
+
+ This calling convention is incompatible with the one normally used
+ on Unix, so you cannot use it if you need to call libraries
+ compiled with the Unix compiler.
+
+ Also, you must provide function prototypes for all functions that
+ take variable numbers of arguments (including `printf'); otherwise
+ incorrect code will be generated for calls to those functions.
+
+ In addition, seriously incorrect code will result if you call a
+ function with too many arguments. (Normally, extra arguments are
+ harmlessly ignored.)
+
+ This option takes its name from the 680x0 `rtd' instruction.
+
+`-mregparam'
+ Use a different function-calling convention where the first two
+ arguments are passed in registers.
+
+ This calling convention is incompatible with the one normally used
+ on Unix, so you cannot use it if you need to call libraries
+ compiled with the Unix compiler.
+
+`-mnoregparam'
+ Do not pass any arguments in registers. This is the default for
+ all targets.
+
+`-msb'
+ It is OK to use the sb as an index register which is always loaded
+ with zero. This is the default for the pc532-netbsd target.
+
+`-mnosb'
+ The sb register is not available for use or has not been
+ initialized to zero by the run time system. This is the default
+ for all targets except the pc532-netbsd. It is also implied
+ whenever `-mhimem' or `-fpic' is set.
+
+`-mhimem'
+ Many ns32000 series addressing modes use displacements of up to
+ 512MB. If an address is above 512MB then displacements from zero
+ can not be used. This option causes code to be generated which
+ can be loaded above 512MB. This may be useful for operating
+ systems or ROM code.
+
+`-mnohimem'
+ Assume code will be loaded in the first 512MB of virtual address
+ space. This is the default for all platforms.
+
+
+\1f
+File: gcc.info, Node: AVR Options, Next: MCore Options, Prev: NS32K Options, Up: Submodel Options
+
+3.17.28 AVR Options
+-------------------
+
+These options are defined for AVR implementations:
+
+`-mmcu=MCU'
+ Specify ATMEL AVR instruction set or MCU type.
+
+ Instruction set avr1 is for the minimal AVR core, not supported by
+ the C compiler, only for assembler programs (MCU types: at90s1200,
+ attiny10, attiny11, attiny12, attiny15, attiny28).
+
+ Instruction set avr2 (default) is for the classic AVR core with up
+ to 8K program memory space (MCU types: at90s2313, at90s2323,
+ attiny22, at90s2333, at90s2343, at90s4414, at90s4433, at90s4434,
+ at90s8515, at90c8534, at90s8535).
+
+ Instruction set avr3 is for the classic AVR core with up to 128K
+ program memory space (MCU types: atmega103, atmega603, at43usb320,
+ at76c711).
+
+ Instruction set avr4 is for the enhanced AVR core with up to 8K
+ program memory space (MCU types: atmega8, atmega83, atmega85).
+
+ Instruction set avr5 is for the enhanced AVR core with up to 128K
+ program memory space (MCU types: atmega16, atmega161, atmega163,
+ atmega32, atmega323, atmega64, atmega128, at43usb355, at94k).
+
+`-msize'
+ Output instruction sizes to the asm file.
+
+`-minit-stack=N'
+ Specify the initial stack address, which may be a symbol or
+ numeric value, `__stack' is the default.
+
+`-mno-interrupts'
+ Generated code is not compatible with hardware interrupts. Code
+ size will be smaller.
+
+`-mcall-prologues'
+ Functions prologues/epilogues expanded as call to appropriate
+ subroutines. Code size will be smaller.
+
+`-mno-tablejump'
+ Do not generate tablejump insns which sometimes increase code size.
- Each kind of machine has a default for what `char' should be. It
- is either like `unsigned char' by default or like `signed char' by
+`-mtiny-stack'
+ Change only the low 8 bits of the stack pointer.
+
+\1f
+File: gcc.info, Node: MCore Options, Next: IA-64 Options, Prev: AVR Options, Up: Submodel Options
+
+3.17.29 MCore Options
+---------------------
+
+These are the `-m' options defined for the Motorola M*Core processors.
+
+`-mhardlit'
+`-mhardlit'
+`-mno-hardlit'
+ Inline constants into the code stream if it can be done in two
+ instructions or less.
+
+`-mdiv'
+`-mdiv'
+`-mno-div'
+ Use the divide instruction. (Enabled by default).
+
+`-mrelax-immediate'
+`-mrelax-immediate'
+`-mno-relax-immediate'
+ Allow arbitrary sized immediates in bit operations.
+
+`-mwide-bitfields'
+`-mwide-bitfields'
+`-mno-wide-bitfields'
+ Always treat bit-fields as int-sized.
+
+`-m4byte-functions'
+`-m4byte-functions'
+`-mno-4byte-functions'
+ Force all functions to be aligned to a four byte boundary.
+
+`-mcallgraph-data'
+`-mcallgraph-data'
+`-mno-callgraph-data'
+ Emit callgraph information.
+
+`-mslow-bytes'
+`-mslow-bytes'
+`-mno-slow-bytes'
+ Prefer word access when reading byte quantities.
+
+`-mlittle-endian'
+`-mlittle-endian'
+`-mbig-endian'
+ Generate code for a little endian target.
+
+`-m210'
+`-m210'
+`-m340'
+ Generate code for the 210 processor.
+
+\1f
+File: gcc.info, Node: IA-64 Options, Next: D30V Options, Prev: MCore Options, Up: Submodel Options
+
+3.17.30 IA-64 Options
+---------------------
+
+These are the `-m' options defined for the Intel IA-64 architecture.
+
+`-mbig-endian'
+ Generate code for a big endian target. This is the default for
+ HPUX.
+
+`-mlittle-endian'
+ Generate code for a little endian target. This is the default for
+ AIX5 and Linux.
+
+`-mgnu-as'
+`-mno-gnu-as'
+ Generate (or don't) code for the GNU assembler. This is the
default.
- Ideally, a portable program should always use `signed char' or
- `unsigned char' when it depends on the signedness of an object.
- But many programs have been written to use plain `char' and expect
- it to be signed, or expect it to be unsigned, depending on the
- machines they were written for. This option, and its inverse, let
- you make such a program work with the opposite default.
-
- The type `char' is always a distinct type from each of `signed
- char' or `unsigned char', even though its behavior is always just
- like one of those two.
-
-`-fsigned-char'
- Let the type `char' be signed, like `signed char'.
-
- Note that this is equivalent to `-fno-unsigned-char', which is the
- negative form of `-funsigned-char'. Likewise, the option
- `-fno-signed-char' is equivalent to `-funsigned-char'.
-
-`-fsigned-bitfields'
-`-funsigned-bitfields'
-`-fno-signed-bitfields'
-`-fno-unsigned-bitfields'
- These options control whether a bit-field is signed or unsigned,
- when the declaration does not use either `signed' or `unsigned'.
- By default, such a bit-field is signed, because this is
- consistent: the basic integer types such as `int' are signed types.
-
- However, when `-traditional' is used, bit-fields are all unsigned
- no matter what.
-
-`-fwritable-strings'
- Store string constants in the writable data segment and don't
- uniquize them. This is for compatibility with old programs which
- assume they can write into string constants. The option
- `-traditional' also has this effect.
-
- Writing into string constants is a very bad idea; "constants"
- should be constant.
-
-`-fallow-single-precision'
- Do not promote single precision math operations to double
- precision, even when compiling with `-traditional'.
-
- Traditional K&R C promotes all floating point operations to double
- precision, regardless of the sizes of the operands. On the
- architecture for which you are compiling, single precision may be
- faster than double precision. If you must use `-traditional',
- but want to use single precision operations when the operands are
- single precision, use this option. This option has no effect
- when compiling with ISO or GNU C conventions (the default).
-
-\1f
-File: gcc.info, Node: C++ Dialect Options, Next: Objective-C Dialect Options, Prev: C Dialect Options, Up: Invoking GCC
-
-Options Controlling C++ Dialect
-===============================
+`-mgnu-ld'
+`-mno-gnu-ld'
+ Generate (or don't) code for the GNU linker. This is the default.
+
+`-mno-pic'
+ Generate code that does not use a global pointer register. The
+ result is not position independent code, and violates the IA-64
+ ABI.
+
+`-mvolatile-asm-stop'
+`-mno-volatile-asm-stop'
+ Generate (or don't) a stop bit immediately before and after
+ volatile asm statements.
+
+`-mb-step'
+ Generate code that works around Itanium B step errata.
+
+`-mregister-names'
+`-mno-register-names'
+ Generate (or don't) `in', `loc', and `out' register names for the
+ stacked registers. This may make assembler output more readable.
+
+`-mno-sdata'
+`-msdata'
+ Disable (or enable) optimizations that use the small data section.
+ This may be useful for working around optimizer bugs.
+
+`-mconstant-gp'
+ Generate code that uses a single constant global pointer value.
+ This is useful when compiling kernel code.
+
+`-mauto-pic'
+ Generate code that is self-relocatable. This implies
+ `-mconstant-gp'. This is useful when compiling firmware code.
+
+`-minline-divide-min-latency'
+ Generate code for inline divides using the minimum latency
+ algorithm.
+
+`-minline-divide-max-throughput'
+ Generate code for inline divides using the maximum throughput
+ algorithm.
+
+`-mno-dwarf2-asm'
+`-mdwarf2-asm'
+ Don't (or do) generate assembler code for the DWARF2 line number
+ debugging info. This may be useful when not using the GNU
+ assembler.
+
+`-mfixed-range=REGISTER-RANGE'
+ Generate code treating the given register range as fixed registers.
+ A fixed register is one that the register allocator can not use.
+ This is useful when compiling kernel code. A register range is
+ specified as two registers separated by a dash. Multiple register
+ ranges can be specified separated by a comma.
- This section describes the command-line options that are only
-meaningful for C++ programs; but you can also use most of the GNU
-compiler options regardless of what language your program is in. For
-example, you might compile a file `firstClass.C' like this:
+\1f
+File: gcc.info, Node: D30V Options, Next: S/390 and zSeries Options, Prev: IA-64 Options, Up: Submodel Options
- g++ -g -frepo -O -c firstClass.C
+3.17.31 D30V Options
+--------------------
-In this example, only `-frepo' is an option meant only for C++
-programs; you can use the other options with any language supported by
-GCC.
+These `-m' options are defined for D30V implementations:
- Here is a list of options that are _only_ for compiling C++ programs:
-
-`-fno-access-control'
- Turn off all access checking. This switch is mainly useful for
- working around bugs in the access control code.
-
-`-fcheck-new'
- Check that the pointer returned by `operator new' is non-null
- before attempting to modify the storage allocated. The current
- Working Paper requires that `operator new' never return a null
- pointer, so this check is normally unnecessary.
-
- An alternative to using this option is to specify that your
- `operator new' does not throw any exceptions; if you declare it
- `throw()', G++ will check the return value. See also `new
- (nothrow)'.
-
-`-fconserve-space'
- Put uninitialized or runtime-initialized global variables into the
- common segment, as C does. This saves space in the executable at
- the cost of not diagnosing duplicate definitions. If you compile
- with this flag and your program mysteriously crashes after
- `main()' has completed, you may have an object that is being
- destroyed twice because two definitions were merged.
-
- This option is no longer useful on most targets, now that support
- has been added for putting variables into BSS without making them
- common.
-
-`-fno-const-strings'
- Give string constants type `char *' instead of type `const char
- *'. By default, G++ uses type `const char *' as required by the
- standard. Even if you use `-fno-const-strings', you cannot
- actually modify the value of a string constant, unless you also use
- `-fwritable-strings'.
-
- This option might be removed in a future release of G++. For
- maximum portability, you should structure your code so that it
- works with string constants that have type `const char *'.
-
-`-fdollars-in-identifiers'
- Accept `$' in identifiers. You can also explicitly prohibit use of
- `$' with the option `-fno-dollars-in-identifiers'. (GNU C allows
- `$' by default on most target systems, but there are a few
- exceptions.) Traditional C allowed the character `$' to form part
- of identifiers. However, ISO C and C++ forbid `$' in identifiers.
-
-`-fno-elide-constructors'
- The C++ standard allows an implementation to omit creating a
- temporary which is only used to initialize another object of the
- same type. Specifying this option disables that optimization, and
- forces G++ to call the copy constructor in all cases.
-
-`-fno-enforce-eh-specs'
- Don't check for violation of exception specifications at runtime.
- This option violates the C++ standard, but may be useful for
- reducing code size in production builds, much like defining
- `NDEBUG'. The compiler will still optimize based on the exception
- specifications.
-
-`-fexternal-templates'
- Cause `#pragma interface' and `implementation' to apply to
- template instantiation; template instances are emitted or not
- according to the location of the template definition. *Note
- Template Instantiation::, for more information.
-
- This option is deprecated.
-
-`-falt-external-templates'
- Similar to `-fexternal-templates', but template instances are
- emitted or not according to the place where they are first
- instantiated. *Note Template Instantiation::, for more
- information.
+`-mextmem'
+ Link the `.text', `.data', `.bss', `.strings', `.rodata',
+ `.rodata1', `.data1' sections into external memory, which starts
+ at location `0x80000000'.
- This option is deprecated.
-
-`-ffor-scope'
-`-fno-for-scope'
- If `-ffor-scope' is specified, the scope of variables declared in
- a for-init-statement is limited to the `for' loop itself, as
- specified by the C++ standard. If `-fno-for-scope' is specified,
- the scope of variables declared in a for-init-statement extends to
- the end of the enclosing scope, as was the case in old versions of
- G++, and other (traditional) implementations of C++.
-
- The default if neither flag is given to follow the standard, but
- to allow and give a warning for old-style code that would
- otherwise be invalid, or have different behavior.
-
-`-fno-gnu-keywords'
- Do not recognize `typeof' as a keyword, so that code can use this
- word as an identifier. You can use the keyword `__typeof__'
- instead. `-ansi' implies `-fno-gnu-keywords'.
-
-`-fno-implicit-templates'
- Never emit code for non-inline templates which are instantiated
- implicitly (i.e. by use); only emit code for explicit
- instantiations. *Note Template Instantiation::, for more
- information.
+`-mextmemory'
+ Same as the `-mextmem' switch.
-`-fno-implicit-inline-templates'
- Don't emit code for implicit instantiations of inline templates,
- either. The default is to handle inlines differently so that
- compiles with and without optimization will need the same set of
- explicit instantiations.
-
-`-fno-implement-inlines'
- To save space, do not emit out-of-line copies of inline functions
- controlled by `#pragma implementation'. This will cause linker
- errors if these functions are not inlined everywhere they are
- called.
-
-`-fms-extensions'
- Disable pedantic warnings about constructs used in MFC, such as
- implicit int and getting a pointer to member function via
- non-standard syntax.
-
-`-fno-nonansi-builtins'
- Disable built-in declarations of functions that are not mandated by
- ANSI/ISO C. These include `ffs', `alloca', `_exit', `index',
- `bzero', `conjf', and other related functions.
-
-`-fno-operator-names'
- Do not treat the operator name keywords `and', `bitand', `bitor',
- `compl', `not', `or' and `xor' as synonyms as keywords.
-
-`-fno-optional-diags'
- Disable diagnostics that the standard says a compiler does not
- need to issue. Currently, the only such diagnostic issued by G++
- is the one for a name having multiple meanings within a class.
-
-`-fpermissive'
- Downgrade messages about nonconformant code from errors to
- warnings. By default, G++ effectively sets `-pedantic-errors'
- without `-pedantic'; this option reverses that. This behavior and
- this option are superseded by `-pedantic', which works as it does
- for GNU C.
-
-`-frepo'
- Enable automatic template instantiation at link time. This option
- also implies `-fno-implicit-templates'. *Note Template
- Instantiation::, for more information.
-
-`-fno-rtti'
- Disable generation of information about every class with virtual
- functions for use by the C++ runtime type identification features
- (`dynamic_cast' and `typeid'). If you don't use those parts of
- the language, you can save some space by using this flag. Note
- that exception handling uses the same information, but it will
- generate it as needed.
-
-`-fstats'
- Emit statistics about front-end processing at the end of the
- compilation. This information is generally only useful to the G++
- development team.
-
-`-ftemplate-depth-N'
- Set the maximum instantiation depth for template classes to N. A
- limit on the template instantiation depth is needed to detect
- endless recursions during template class instantiation. ANSI/ISO
- C++ conforming programs must not rely on a maximum depth greater
- than 17.
-
-`-fuse-cxa-atexit'
- Register destructors for objects with static storage duration with
- the `__cxa_atexit' function rather than the `atexit' function.
- This option is required for fully standards-compliant handling of
- static destructors, but will only work if your C library supports
- `__cxa_atexit'.
-
-`-fvtable-gc'
- Emit special relocations for vtables and virtual function
- references so that the linker can identify unused virtual
- functions and zero out vtable slots that refer to them. This is
- most useful with `-ffunction-sections' and `-Wl,--gc-sections', in
- order to also discard the functions themselves.
-
- This optimization requires GNU as and GNU ld. Not all systems
- support this option. `-Wl,--gc-sections' is ignored without
- `-static'.
-
-`-fno-weak'
- Do not use weak symbol support, even if it is provided by the
- linker. By default, G++ will use weak symbols if they are
- available. This option exists only for testing, and should not be
- used by end-users; it will result in inferior code and has no
- benefits. This option may be removed in a future release of G++.
-
-`-nostdinc++'
- Do not search for header files in the standard directories
- specific to C++, but do still search the other standard
- directories. (This option is used when building the C++ library.)
-
- In addition, these optimization, warning, and code generation options
-have meanings only for C++ programs:
-
-`-fno-default-inline'
- Do not assume `inline' for functions defined inside a class scope.
- *Note Options That Control Optimization: Optimize Options. Note
- that these functions will have linkage like inline functions; they
- just won't be inlined by default.
-
-`-Wabi (C++ only)'
- Warn when G++ generates code that is probably not compatible with
- the vendor-neutral C++ ABI. Although an effort has been made to
- warn about all such cases, there are probably some cases that are
- not warned about, even though G++ is generating incompatible code.
- There may also be cases where warnings are emitted even though
- the code that is generated will be compatible.
-
- You should rewrite your code to avoid these warnings if you are
- concerned about the fact that code generated by G++ may not be
- binary compatible with code generated by other compilers.
-
- The known incompatibilites at this point include:
-
- * Incorrect handling of tail-padding for bit-fields. G++ may
- attempt to pack data into the same byte as a base class. For
- example:
-
- struct A { virtual void f(); int f1 : 1; };
- struct B : public A { int f2 : 1; };
-
- In this case, G++ will place `B::f2' into the same byte
- as`A::f1'; other compilers will not. You can avoid this
- problem by explicitly padding `A' so that its size is a
- multiple of the byte size on your platform; that will cause
- G++ and other compilers to layout `B' identically.
-
- * Incorrect handling of tail-padding for virtual bases. G++
- does not use tail padding when laying out virtual bases. For
- example:
-
- struct A { virtual void f(); char c1; };
- struct B { B(); char c2; };
- struct C : public A, public virtual B {};
-
- In this case, G++ will not place `B' into the tail-padding for
- `A'; other compilers will. You can avoid this problem by
- explicitly padding `A' so that its size is a multiple of its
- alignment (ignoring virtual base classes); that will cause
- G++ and other compilers to layout `C' identically.
-
-
-`-Wctor-dtor-privacy (C++ only)'
- Warn when a class seems unusable, because all the constructors or
- destructors in a class are private and the class has no friends or
- public static member functions.
-
-`-Wnon-virtual-dtor (C++ only)'
- Warn when a class declares a non-virtual destructor that should
- probably be virtual, because it looks like the class will be used
- polymorphically.
-
-`-Wreorder (C++ only)'
- Warn when the order of member initializers given in the code does
- not match the order in which they must be executed. For instance:
-
- struct A {
- int i;
- int j;
- A(): j (0), i (1) { }
- };
+`-monchip'
+ Link the `.text' section into onchip text memory, which starts at
+ location `0x0'. Also link `.data', `.bss', `.strings', `.rodata',
+ `.rodata1', `.data1' sections into onchip data memory, which
+ starts at location `0x20000000'.
+
+`-mno-asm-optimize'
+`-masm-optimize'
+ Disable (enable) passing `-O' to the assembler when optimizing.
+ The assembler uses the `-O' option to automatically parallelize
+ adjacent short instructions where possible.
- Here the compiler will warn that the member initializers for `i'
- and `j' will be rearranged to match the declaration order of the
- members.
+`-mbranch-cost=N'
+ Increase the internal costs of branches to N. Higher costs means
+ that the compiler will issue more instructions to avoid doing a
+ branch. The default is 2.
- The following `-W...' options are not affected by `-Wall'.
+`-mcond-exec=N'
+ Specify the maximum number of conditionally executed instructions
+ that replace a branch. The default is 4.
-`-Weffc++ (C++ only)'
- Warn about violations of the following style guidelines from Scott
- Meyers' `Effective C++' book:
+\1f
+File: gcc.info, Node: S/390 and zSeries Options, Next: CRIS Options, Prev: D30V Options, Up: Submodel Options
+
+3.17.32 S/390 and zSeries Options
+---------------------------------
- * Item 11: Define a copy constructor and an assignment
- operator for classes with dynamically allocated memory.
+These are the `-m' options defined for the S/390 and zSeries
+architecture.
- * Item 12: Prefer initialization to assignment in constructors.
+`-mhard-float'
+`-msoft-float'
+ Use (do not use) the hardware floating-point instructions and
+ registers for floating-point operations. When `-msoft-float' is
+ specified, functions in `libgcc.a' will be used to perform
+ floating-point operations. When `-mhard-float' is specified, the
+ compiler generates IEEE floating-point instructions. This is the
+ default.
- * Item 14: Make destructors virtual in base classes.
+`-mbackchain'
+`-mno-backchain'
+ Generate (or do not generate) code which maintains an explicit
+ backchain within the stack frame that points to the caller's frame.
+ This is currently needed to allow debugging. The default is to
+ generate the backchain.
+
+`-msmall-exec'
+`-mno-small-exec'
+ Generate (or do not generate) code using the `bras' instruction to
+ do subroutine calls. This only works reliably if the total
+ executable size does not exceed 64k. The default is to use the
+ `basr' instruction instead, which does not have this limitation.
+
+`-m64'
+`-m31'
+ When `-m31' is specified, generate code compliant to the Linux for
+ S/390 ABI. When `-m64' is specified, generate code compliant to
+ the Linux for zSeries ABI. This allows GCC in particular to
+ generate 64-bit instructions. For the `s390' targets, the default
+ is `-m31', while the `s390x' targets default to `-m64'.
+
+`-mmvcle'
+`-mno-mvcle'
+ Generate (or do not generate) code using the `mvcle' instruction
+ to perform block moves. When `-mno-mvcle' is specifed, use a
+ `mvc' loop instead. This is the default.
+
+`-mdebug'
+`-mno-debug'
+ Print (or do not print) additional debug information when
+ compiling. The default is to not print debug information.
- * Item 15: Have `operator=' return a reference to `*this'.
- * Item 23: Don't try to return a reference when you must
- return an object.
+\1f
+File: gcc.info, Node: CRIS Options, Next: MMIX Options, Prev: S/390 and zSeries Options, Up: Submodel Options
+
+3.17.33 CRIS Options
+--------------------
+
+These options are defined specifically for the CRIS ports.
+
+`-march=ARCHITECTURE-TYPE'
+`-mcpu=ARCHITECTURE-TYPE'
+ Generate code for the specified architecture. The choices for
+ ARCHITECTURE-TYPE are `v3', `v8' and `v10' for respectively
+ ETRAX 4, ETRAX 100, and ETRAX 100 LX. Default is `v0' except for
+ cris-axis-linux-gnu, where the default is `v10'.
+
+`-mtune=ARCHITECTURE-TYPE'
+ Tune to ARCHITECTURE-TYPE everything applicable about the generated
+ code, except for the ABI and the set of available instructions.
+ The choices for ARCHITECTURE-TYPE are the same as for
+ `-march=ARCHITECTURE-TYPE'.
+
+`-mmax-stack-frame=N'
+ Warn when the stack frame of a function exceeds N bytes.
+
+`-melinux-stacksize=N'
+ Only available with the `cris-axis-aout' target. Arranges for
+ indications in the program to the kernel loader that the stack of
+ the program should be set to N bytes.
+
+`-metrax4'
+`-metrax100'
+ The options `-metrax4' and `-metrax100' are synonyms for
+ `-march=v3' and `-march=v8' respectively.
+
+`-mpdebug'
+ Enable CRIS-specific verbose debug-related information in the
+ assembly code. This option also has the effect to turn off the
+ `#NO_APP' formatted-code indicator to the assembler at the
+ beginning of the assembly file.
+
+`-mcc-init'
+ Do not use condition-code results from previous instruction;
+ always emit compare and test instructions before use of condition
+ codes.
+
+`-mno-side-effects'
+ Do not emit instructions with side-effects in addressing modes
+ other than post-increment.
+
+`-mstack-align'
+`-mno-stack-align'
+`-mdata-align'
+`-mno-data-align'
+`-mconst-align'
+`-mno-const-align'
+ These options (no-options) arranges (eliminate arrangements) for
+ the stack-frame, individual data and constants to be aligned for
+ the maximum single data access size for the chosen CPU model. The
+ default is to arrange for 32-bit alignment. ABI details such as
+ structure layout are not affected by these options.
+
+`-m32-bit'
+`-m16-bit'
+`-m8-bit'
+ Similar to the stack- data- and const-align options above, these
+ options arrange for stack-frame, writable data and constants to
+ all be 32-bit, 16-bit or 8-bit aligned. The default is 32-bit
+ alignment.
+
+`-mno-prologue-epilogue'
+`-mprologue-epilogue'
+ With `-mno-prologue-epilogue', the normal function prologue and
+ epilogue that sets up the stack-frame are omitted and no return
+ instructions or return sequences are generated in the code. Use
+ this option only together with visual inspection of the compiled
+ code: no warnings or errors are generated when call-saved
+ registers must be saved, or storage for local variable needs to be
+ allocated.
+
+`-mno-gotplt'
+`-mgotplt'
+ With `-fpic' and `-fPIC', don't generate (do generate) instruction
+ sequences that load addresses for functions from the PLT part of
+ the GOT rather than (traditional on other architectures) calls to
+ the PLT. The default is `-mgotplt'.
+
+`-maout'
+ Legacy no-op option only recognized with the cris-axis-aout target.
+
+`-melf'
+ Legacy no-op option only recognized with the cris-axis-elf and
+ cris-axis-linux-gnu targets.
+
+`-melinux'
+ Only recognized with the cris-axis-aout target, where it selects a
+ GNU/linux-like multilib, include files and instruction set for
+ `-march=v8'.
+
+`-mlinux'
+ Legacy no-op option only recognized with the cris-axis-linux-gnu
+ target.
+
+`-sim'
+ This option, recognized for the cris-axis-aout and cris-axis-elf
+ arranges to link with input-output functions from a simulator
+ library. Code, initialized data and zero-initialized data are
+ allocated consecutively.
+
+`-sim2'
+ Like `-sim', but pass linker options to locate initialized data at
+ 0x40000000 and zero-initialized data at 0x80000000.
+\1f
+File: gcc.info, Node: MMIX Options, Next: PDP-11 Options, Prev: CRIS Options, Up: Submodel Options
+
+3.17.34 MMIX Options
+--------------------
+
+These options are defined for the MMIX:
+
+`-mlibfuncs'
+`-mno-libfuncs'
+ Specify that intrinsic library functions are being compiled,
+ passing all values in registers, no matter the size.
+
+`-mepsilon'
+`-mno-epsilon'
+ Generate floating-point comparison instructions that compare with
+ respect to the `rE' epsilon register.
+
+`-mabi=mmixware'
+`-mabi=gnu'
+ Generate code that passes function parameters and return values
+ that (in the called function) are seen as registers `$0' and up,
+ as opposed to the GNU ABI which uses global registers `$231' and
+ up.
+
+`-mzero-extend'
+`-mno-zero-extend'
+ When reading data from memory in sizes shorter than 64 bits, use
+ (do not use) zero-extending load instructions by default, rather
+ than sign-extending ones.
+
+`-mknuthdiv'
+`-mno-knuthdiv'
+ Make the result of a division yielding a remainder have the same
+ sign as the divisor. With the default, `-mno-knuthdiv', the sign
+ of the remainder follows the sign of the dividend. Both methods
+ are arithmetically valid, the latter being almost exclusively used.
+
+`-mtoplevel-symbols'
+`-mno-toplevel-symbols'
+ Prepend (do not prepend) a `:' to all global symbols, so the
+ assembly code can be used with the `PREFIX' assembly directive.
+
+`-melf'
+ Generate an executable in the ELF format, rather than the default
+ `mmo' format used by the `mmix' simulator.
+
+`-mbranch-predict'
+`-mno-branch-predict'
+ Use (do not use) the probable-branch instructions, when static
+ branch prediction indicates a probable branch.
+
+`-mbase-addresses'
+`-mno-base-addresses'
+ Generate (do not generate) code that uses _base addresses_. Using
+ a base address automatically generates a request (handled by the
+ assembler and the linker) for a constant to be set up in a global
+ register. The register is used for one or more base address
+ requests within the range 0 to 255 from the value held in the
+ register. The generally leads to short and fast code, but the
+ number of different data items that can be addressed is limited.
+ This means that a program that uses lots of static data may
+ require `-mno-base-addresses'.
- and about violations of the following style guidelines from Scott
- Meyers' `More Effective C++' book:
+\1f
+File: gcc.info, Node: PDP-11 Options, Next: Xstormy16 Options, Prev: MMIX Options, Up: Submodel Options
- * Item 6: Distinguish between prefix and postfix forms of
- increment and decrement operators.
+3.17.35 PDP-11 Options
+----------------------
- * Item 7: Never overload `&&', `||', or `,'.
+These options are defined for the PDP-11:
+`-mfpu'
+ Use hardware FPP floating point. This is the default. (FIS
+ floating point on the PDP-11/40 is not supported.)
- If you use this option, you should be aware that the standard
- library headers do not obey all of these guidelines; you can use
- `grep -v' to filter out those warnings.
+`-msoft-float'
+ Do not use hardware floating point.
-`-Wno-deprecated (C++ only)'
- Do not warn about usage of deprecated features. *Note Deprecated
- Features::.
+`-mac0'
+ Return floating-point results in ac0 (fr0 in Unix assembler
+ syntax).
-`-Wno-non-template-friend (C++ only)'
- Disable warnings when non-templatized friend functions are declared
- within a template. With the advent of explicit template
- specification support in G++, if the name of the friend is an
- unqualified-id (i.e., `friend foo(int)'), the C++ language
- specification demands that the friend declare or define an
- ordinary, nontemplate function. (Section 14.5.3). Before G++
- implemented explicit specification, unqualified-ids could be
- interpreted as a particular specialization of a templatized
- function. Because this non-conforming behavior is no longer the
- default behavior for G++, `-Wnon-template-friend' allows the
- compiler to check existing code for potential trouble spots, and
- is on by default. This new compiler behavior can be turned off
- with `-Wno-non-template-friend' which keeps the conformant
- compiler code but disables the helpful warning.
+`-mno-ac0'
+ Return floating-point results in memory. This is the default.
-`-Wold-style-cast (C++ only)'
- Warn if an old-style (C-style) cast to a non-void type is used
- within a C++ program. The new-style casts (`static_cast',
- `reinterpret_cast', and `const_cast') are less vulnerable to
- unintended effects, and much easier to grep for.
+`-m40'
+ Generate code for a PDP-11/40.
-`-Woverloaded-virtual (C++ only)'
- Warn when a function declaration hides virtual functions from a
- base class. For example, in:
+`-m45'
+ Generate code for a PDP-11/45. This is the default.
- struct A {
- virtual void f();
- };
-
- struct B: public A {
- void f(int);
- };
+`-m10'
+ Generate code for a PDP-11/10.
- the `A' class version of `f' is hidden in `B', and code like this:
+`-mbcopy-builtin'
+ Use inline `movstrhi' patterns for copying memory. This is the
+ default.
- B* b;
- b->f();
+`-mbcopy'
+ Do not use inline `movstrhi' patterns for copying memory.
- will fail to compile.
+`-mint16'
+`-mno-int32'
+ Use 16-bit `int'. This is the default.
-`-Wno-pmf-conversions (C++ only)'
- Disable the diagnostic for converting a bound pointer to member
- function to a plain pointer.
+`-mint32'
+`-mno-int16'
+ Use 32-bit `int'.
-`-Wsign-promo (C++ only)'
- Warn when overload resolution chooses a promotion from unsigned or
- enumeral type to a signed type over a conversion to an unsigned
- type of the same size. Previous versions of G++ would try to
- preserve unsignedness, but the standard mandates the current
- behavior.
+`-mfloat64'
+`-mno-float32'
+ Use 64-bit `float'. This is the default.
-`-Wsynth (C++ only)'
- Warn when G++'s synthesis behavior does not match that of cfront.
- For instance:
+`-mfloat32'
- struct A {
- operator int ();
- A& operator = (int);
- };
-
- main ()
- {
- A a,b;
- a = b;
- }
+`-mno-float64'
+ Use 32-bit `float'.
+
+`-mabshi'
+ Use `abshi2' pattern. This is the default.
+
+`-mno-abshi'
+ Do not use `abshi2' pattern.
+
+`-mbranch-expensive'
+ Pretend that branches are expensive. This is for experimenting
+ with code generation only.
+
+`-mbranch-cheap'
+ Do not pretend that branches are expensive. This is the default.
- In this example, G++ will synthesize a default `A& operator =
- (const A&);', while cfront will use the user-defined `operator ='.
+`-msplit'
+ Generate code for a system with split I&D.
+
+`-mno-split'
+ Generate code for a system without split I&D. This is the default.
+
+`-munix-asm'
+ Use Unix assembler syntax. This is the default when configured for
+ `pdp11-*-bsd'.
+
+`-mdec-asm'
+ Use DEC assembler syntax. This is the default when configured for
+ any PDP-11 target other than `pdp11-*-bsd'.
\1f
-File: gcc.info, Node: Objective-C Dialect Options, Next: Language Independent Options, Prev: C++ Dialect Options, Up: Invoking GCC
+File: gcc.info, Node: Xstormy16 Options, Next: Xtensa Options, Prev: PDP-11 Options, Up: Submodel Options
-Options Controlling Objective-C Dialect
-=======================================
+3.17.36 Xstormy16 Options
+-------------------------
+
+These options are defined for Xstormy16:
+
+`-msim'
+ Choose startup files and linker script suitable for the simulator.
+
+\1f
+File: gcc.info, Node: Xtensa Options, Prev: Xstormy16 Options, Up: Submodel Options
+
+3.17.37 Xtensa Options
+----------------------
+
+The Xtensa architecture is designed to support many different
+configurations. The compiler's default options can be set to match a
+particular Xtensa configuration by copying a configuration file into the
+GCC sources when building GCC. The options below may be used to
+override the default options.
+
+`-mbig-endian'
+`-mlittle-endian'
+ Specify big-endian or little-endian byte ordering for the target
+ Xtensa processor.
+
+`-mdensity'
+`-mno-density'
+ Enable or disable use of the optional Xtensa code density
+ instructions.
+
+`-mmac16'
+`-mno-mac16'
+ Enable or disable use of the Xtensa MAC16 option. When enabled,
+ GCC will generate MAC16 instructions from standard C code, with the
+ limitation that it will use neither the MR register file nor any
+ instruction that operates on the MR registers. When this option is
+ disabled, GCC will translate 16-bit multiply/accumulate operations
+ to a combination of core instructions and library calls, depending
+ on whether any other multiplier options are enabled.
+
+`-mmul16'
+`-mno-mul16'
+ Enable or disable use of the 16-bit integer multiplier option.
+ When enabled, the compiler will generate 16-bit multiply
+ instructions for multiplications of 16 bits or smaller in standard
+ C code. When this option is disabled, the compiler will either
+ use 32-bit multiply or MAC16 instructions if they are available or
+ generate library calls to perform the multiply operations using
+ shifts and adds.
+
+`-mmul32'
+`-mno-mul32'
+ Enable or disable use of the 32-bit integer multiplier option.
+ When enabled, the compiler will generate 32-bit multiply
+ instructions for multiplications of 32 bits or smaller in standard
+ C code. When this option is disabled, the compiler will generate
+ library calls to perform the multiply operations using either
+ shifts and adds or 16-bit multiply instructions if they are
+ available.
+
+`-mnsa'
+`-mno-nsa'
+ Enable or disable use of the optional normalization shift amount
+ (`NSA') instructions to implement the built-in `ffs' function.
+
+`-mminmax'
+`-mno-minmax'
+ Enable or disable use of the optional minimum and maximum value
+ instructions.
+
+`-msext'
+`-mno-sext'
+ Enable or disable use of the optional sign extend (`SEXT')
+ instruction.
+
+`-mbooleans'
+`-mno-booleans'
+ Enable or disable support for the boolean register file used by
+ Xtensa coprocessors. This is not typically useful by itself but
+ may be required for other options that make use of the boolean
+ registers (e.g., the floating-point option).
+
+`-mhard-float'
+`-msoft-float'
+ Enable or disable use of the floating-point option. When enabled,
+ GCC generates floating-point instructions for 32-bit `float'
+ operations. When this option is disabled, GCC generates library
+ calls to emulate 32-bit floating-point operations using integer
+ instructions. Regardless of this option, 64-bit `double'
+ operations are always emulated with calls to library functions.
+
+`-mfused-madd'
+`-mno-fused-madd'
+ Enable or disable use of fused multiply/add and multiply/subtract
+ instructions in the floating-point option. This has no effect if
+ the floating-point option is not also enabled. Disabling fused
+ multiply/add and multiply/subtract instructions forces the
+ compiler to use separate instructions for the multiply and
+ add/subtract operations. This may be desirable in some cases
+ where strict IEEE 754-compliant results are required: the fused
+ multiply add/subtract instructions do not round the intermediate
+ result, thereby producing results with _more_ bits of precision
+ than specified by the IEEE standard. Disabling fused multiply
+ add/subtract instructions also ensures that the program output is
+ not sensitive to the compiler's ability to combine multiply and
+ add/subtract operations.
+
+`-mserialize-volatile'
+`-mno-serialize-volatile'
+ When this option is enabled, GCC inserts `MEMW' instructions before
+ `volatile' memory references to guarantee sequential consistency.
+ The default is `-mserialize-volatile'. Use
+ `-mno-serialize-volatile' to omit the `MEMW' instructions.
+
+`-mtext-section-literals'
+`-mno-text-section-literals'
+ Control the treatment of literal pools. The default is
+ `-mno-text-section-literals', which places literals in a separate
+ section in the output file. This allows the literal pool to be
+ placed in a data RAM/ROM, and it also allows the linker to combine
+ literal pools from separate object files to remove redundant
+ literals and improve code size. With `-mtext-section-literals',
+ the literals are interspersed in the text section in order to keep
+ them as close as possible to their references. This may be
+ necessary for large assembly files.
+
+`-mtarget-align'
+`-mno-target-align'
+ When this option is enabled, GCC instructs the assembler to
+ automatically align instructions to reduce branch penalties at the
+ expense of some code density. The assembler attempts to widen
+ density instructions to align branch targets and the instructions
+ following call instructions. If there are not enough preceding
+ safe density instructions to align a target, no widening will be
+ performed. The default is `-mtarget-align'. These options do not
+ affect the treatment of auto-aligned instructions like `LOOP',
+ which the assembler will always align, either by widening density
+ instructions or by inserting no-op instructions.
+
+`-mlongcalls'
+`-mno-longcalls'
+ When this option is enabled, GCC instructs the assembler to
+ translate direct calls to indirect calls unless it can determine
+ that the target of a direct call is in the range allowed by the
+ call instruction. This translation typically occurs for calls to
+ functions in other source files. Specifically, the assembler
+ translates a direct `CALL' instruction into an `L32R' followed by
+ a `CALLX' instruction. The default is `-mno-longcalls'. This
+ option should be used in programs where the call target can
+ potentially be out of range. This option is implemented in the
+ assembler, not the compiler, so the assembly code generated by GCC
+ will still show direct call instructions--look at the disassembled
+ object code to see the actual instructions. Note that the
+ assembler will use an indirect call for every cross-file call, not
+ just those that really will be out of range.
- This section describes the command-line options that are only
-meaningful for Objective-C programs; but you can also use most of the
-GNU compiler options regardless of what language your program is in.
-For example, you might compile a file `some_class.m' like this:
+\1f
+File: gcc.info, Node: Code Gen Options, Next: Environment Variables, Prev: Submodel Options, Up: Invoking GCC
+
+3.18 Options for Code Generation Conventions
+============================================
+
+These machine-independent options control the interface conventions
+used in code generation.
+
+ Most of them have both positive and negative forms; the negative form
+of `-ffoo' would be `-fno-foo'. In the table below, only one of the
+forms is listed--the one which is not the default. You can figure out
+the other form by either removing `no-' or adding it.
+
+`-fexceptions'
+ Enable exception handling. Generates extra code needed to
+ propagate exceptions. For some targets, this implies GCC will
+ generate frame unwind information for all functions, which can
+ produce significant data size overhead, although it does not
+ affect execution. If you do not specify this option, GCC will
+ enable it by default for languages like C++ which normally require
+ exception handling, and disable it for languages like C that do
+ not normally require it. However, you may need to enable this
+ option when compiling C code that needs to interoperate properly
+ with exception handlers written in C++. You may also wish to
+ disable this option if you are compiling older C++ programs that
+ don't use exception handling.
+
+`-fnon-call-exceptions'
+ Generate code that allows trapping instructions to throw
+ exceptions. Note that this requires platform-specific runtime
+ support that does not exist everywhere. Moreover, it only allows
+ _trapping_ instructions to throw exceptions, i.e. memory
+ references or floating point instructions. It does not allow
+ exceptions to be thrown from arbitrary signal handlers such as
+ `SIGALRM'.
+
+`-funwind-tables'
+ Similar to `-fexceptions', except that it will just generate any
+ needed static data, but will not affect the generated code in any
+ other way. You will normally not enable this option; instead, a
+ language processor that needs this handling would enable it on
+ your behalf.
+
+`-fasynchronous-unwind-tables'
+ Generate unwind table in dwarf2 format, if supported by target
+ machine. The table is exact at each instruction boundary, so it
+ can be used for stack unwinding from asynchronous events (such as
+ debugger or garbage collector).
+
+`-fpcc-struct-return'
+ Return "short" `struct' and `union' values in memory like longer
+ ones, rather than in registers. This convention is less
+ efficient, but it has the advantage of allowing intercallability
+ between GCC-compiled files and files compiled with other
+ compilers, particularly the Portable C Compiler (pcc).
+
+ The precise convention for returning structures in memory depends
+ on the target configuration macros.
+
+ Short structures and unions are those whose size and alignment
+ match that of some integer type.
+
+ *Warning:* code compiled with the `-fpcc-struct-return' switch is
+ not binary compatible with code compiled with the
+ `-freg-struct-return' switch. Use it to conform to a non-default
+ application binary interface.
+
+`-freg-struct-return'
+ Return `struct' and `union' values in registers when possible.
+ This is more efficient for small structures than
+ `-fpcc-struct-return'.
+
+ If you specify neither `-fpcc-struct-return' nor
+ `-freg-struct-return', GCC defaults to whichever convention is
+ standard for the target. If there is no standard convention, GCC
+ defaults to `-fpcc-struct-return', except on targets where GCC is
+ the principal compiler. In those cases, we can choose the
+ standard, and we chose the more efficient register return
+ alternative.
+
+ *Warning:* code compiled with the `-freg-struct-return' switch is
+ not binary compatible with code compiled with the
+ `-fpcc-struct-return' switch. Use it to conform to a non-default
+ application binary interface.
+
+`-fshort-enums'
+ Allocate to an `enum' type only as many bytes as it needs for the
+ declared range of possible values. Specifically, the `enum' type
+ will be equivalent to the smallest integer type which has enough
+ room.
+
+ *Warning:* the `-fshort-enums' switch causes GCC to generate code
+ that is not binary compatible with code generated without that
+ switch. Use it to conform to a non-default application binary
+ interface.
+
+`-fshort-double'
+ Use the same size for `double' as for `float'.
+
+ *Warning:* the `-fshort-double' switch causes GCC to generate code
+ that is not binary compatible with code generated without that
+ switch. Use it to conform to a non-default application binary
+ interface.
+
+`-fshort-wchar'
+ Override the underlying type for `wchar_t' to be `short unsigned
+ int' instead of the default for the target. This option is useful
+ for building programs to run under WINE.
+
+ *Warning:* the `-fshort-wchar' switch causes GCC to generate code
+ that is not binary compatible with code generated without that
+ switch. Use it to conform to a non-default application binary
+ interface.
+
+`-fshared-data'
+ Requests that the data and non-`const' variables of this
+ compilation be shared data rather than private data. The
+ distinction makes sense only on certain operating systems, where
+ shared data is shared between processes running the same program,
+ while private data exists in one copy per process.
+
+`-fno-common'
+ In C, allocate even uninitialized global variables in the data
+ section of the object file, rather than generating them as common
+ blocks. This has the effect that if the same variable is declared
+ (without `extern') in two different compilations, you will get an
+ error when you link them. The only reason this might be useful is
+ if you wish to verify that the program will work on other systems
+ which always work this way.
+
+`-fno-ident'
+ Ignore the `#ident' directive.
+
+`-fno-gnu-linker'
+ Do not output global initializations (such as C++ constructors and
+ destructors) in the form used by the GNU linker (on systems where
+ the GNU linker is the standard method of handling them). Use this
+ option when you want to use a non-GNU linker, which also requires
+ using the `collect2' program to make sure the system linker
+ includes constructors and destructors. (`collect2' is included in
+ the GCC distribution.) For systems which _must_ use `collect2',
+ the compiler driver `gcc' is configured to do this automatically.
+
+`-finhibit-size-directive'
+ Don't output a `.size' assembler directive, or anything else that
+ would cause trouble if the function is split in the middle, and the
+ two halves are placed at locations far apart in memory. This
+ option is used when compiling `crtstuff.c'; you should not need to
+ use it for anything else.
+
+`-fverbose-asm'
+ Put extra commentary information in the generated assembly code to
+ make it more readable. This option is generally only of use to
+ those who actually need to read the generated assembly code
+ (perhaps while debugging the compiler itself).
+
+ `-fno-verbose-asm', the default, causes the extra information to
+ be omitted and is useful when comparing two assembler files.
+
+`-fvolatile'
+ Consider all memory references through pointers to be volatile.
+
+`-fvolatile-global'
+ Consider all memory references to extern and global data items to
+ be volatile. GCC does not consider static data items to be
+ volatile because of this switch.
+
+`-fvolatile-static'
+ Consider all memory references to static data to be volatile.
+
+`-fpic'
+ Generate position-independent code (PIC) suitable for use in a
+ shared library, if supported for the target machine. Such code
+ accesses all constant addresses through a global offset table
+ (GOT). The dynamic loader resolves the GOT entries when the
+ program starts (the dynamic loader is not part of GCC; it is part
+ of the operating system). If the GOT size for the linked
+ executable exceeds a machine-specific maximum size, you get an
+ error message from the linker indicating that `-fpic' does not
+ work; in that case, recompile with `-fPIC' instead. (These
+ maximums are 16k on the m88k, 8k on the Sparc, and 32k on the m68k
+ and RS/6000. The 386 has no such limit.)
+
+ Position-independent code requires special support, and therefore
+ works only on certain machines. For the 386, GCC supports PIC for
+ System V but not for the Sun 386i. Code generated for the IBM
+ RS/6000 is always position-independent.
+
+`-fPIC'
+ If supported for the target machine, emit position-independent
+ code, suitable for dynamic linking and avoiding any limit on the
+ size of the global offset table. This option makes a difference
+ on the m68k, m88k, and the Sparc.
+
+ Position-independent code requires special support, and therefore
+ works only on certain machines.
+
+`-ffixed-REG'
+ Treat the register named REG as a fixed register; generated code
+ should never refer to it (except perhaps as a stack pointer, frame
+ pointer or in some other fixed role).
+
+ REG must be the name of a register. The register names accepted
+ are machine-specific and are defined in the `REGISTER_NAMES' macro
+ in the machine description macro file.
+
+ This flag does not have a negative form, because it specifies a
+ three-way choice.
+
+`-fcall-used-REG'
+ Treat the register named REG as an allocable register that is
+ clobbered by function calls. It may be allocated for temporaries
+ or variables that do not live across a call. Functions compiled
+ this way will not save and restore the register REG.
+
+ It is an error to used this flag with the frame pointer or stack
+ pointer. Use of this flag for other registers that have fixed
+ pervasive roles in the machine's execution model will produce
+ disastrous results.
+
+ This flag does not have a negative form, because it specifies a
+ three-way choice.
+
+`-fcall-saved-REG'
+ Treat the register named REG as an allocable register saved by
+ functions. It may be allocated even for temporaries or variables
+ that live across a call. Functions compiled this way will save
+ and restore the register REG if they use it.
+
+ It is an error to used this flag with the frame pointer or stack
+ pointer. Use of this flag for other registers that have fixed
+ pervasive roles in the machine's execution model will produce
+ disastrous results.
+
+ A different sort of disaster will result from the use of this flag
+ for a register in which function values may be returned.
+
+ This flag does not have a negative form, because it specifies a
+ three-way choice.
+
+`-fpack-struct'
+ Pack all structure members together without holes.
+
+ *Warning:* the `-fpack-struct' switch causes GCC to generate code
+ that is not binary compatible with code generated without that
+ switch. Additionally, it makes the code suboptimial. Use it to
+ conform to a non-default application binary interface.
+
+`-finstrument-functions'
+ Generate instrumentation calls for entry and exit to functions.
+ Just after function entry and just before function exit, the
+ following profiling functions will be called with the address of
+ the current function and its call site. (On some platforms,
+ `__builtin_return_address' does not work beyond the current
+ function, so the call site information may not be available to the
+ profiling functions otherwise.)
+
+ void __cyg_profile_func_enter (void *this_fn,
+ void *call_site);
+ void __cyg_profile_func_exit (void *this_fn,
+ void *call_site);
+
+ The first argument is the address of the start of the current
+ function, which may be looked up exactly in the symbol table.
+
+ This instrumentation is also done for functions expanded inline in
+ other functions. The profiling calls will indicate where,
+ conceptually, the inline function is entered and exited. This
+ means that addressable versions of such functions must be
+ available. If all your uses of a function are expanded inline,
+ this may mean an additional expansion of code size. If you use
+ `extern inline' in your C code, an addressable version of such
+ functions must be provided. (This is normally the case anyways,
+ but if you get lucky and the optimizer always expands the
+ functions inline, you might have gotten away without providing
+ static copies.)
+
+ A function may be given the attribute `no_instrument_function', in
+ which case this instrumentation will not be done. This can be
+ used, for example, for the profiling functions listed above,
+ high-priority interrupt routines, and any functions from which the
+ profiling functions cannot safely be called (perhaps signal
+ handlers, if the profiling routines generate output or allocate
+ memory).
+
+`-fstack-check'
+ Generate code to verify that you do not go beyond the boundary of
+ the stack. You should specify this flag if you are running in an
+ environment with multiple threads, but only rarely need to specify
+ it in a single-threaded environment since stack overflow is
+ automatically detected on nearly all systems if there is only one
+ stack.
+
+ Note that this switch does not actually cause checking to be done;
+ the operating system must do that. The switch causes generation
+ of code to ensure that the operating system sees the stack being
+ extended.
+
+`-fstack-limit-register=REG'
+`-fstack-limit-symbol=SYM'
+`-fno-stack-limit'
+ Generate code to ensure that the stack does not grow beyond a
+ certain value, either the value of a register or the address of a
+ symbol. If the stack would grow beyond the value, a signal is
+ raised. For most targets, the signal is raised before the stack
+ overruns the boundary, so it is possible to catch the signal
+ without taking special precautions.
+
+ For instance, if the stack starts at absolute address `0x80000000'
+ and grows downwards, you can use the flags
+ `-fstack-limit-symbol=__stack_limit' and
+ `-Wl,--defsym,__stack_limit=0x7ffe0000' to enforce a stack limit
+ of 128KB. Note that this may only work with the GNU linker.
+
+`-fargument-alias'
+`-fargument-noalias'
+`-fargument-noalias-global'
+ Specify the possible relationships among parameters and between
+ parameters and global data.
+
+ `-fargument-alias' specifies that arguments (parameters) may alias
+ each other and may alias global storage.
+ `-fargument-noalias' specifies that arguments do not alias each
+ other, but may alias global storage.
+ `-fargument-noalias-global' specifies that arguments do not alias
+ each other and do not alias global storage.
+
+ Each language will automatically use whatever option is required by
+ the language standard. You should not need to use these options
+ yourself.
+
+`-fleading-underscore'
+ This option and its counterpart, `-fno-leading-underscore',
+ forcibly change the way C symbols are represented in the object
+ file. One use is to help link with legacy assembly code.
+
+ *Warning:* the `-fleading-underscore' switch causes GCC to
+ generate code that is not binary compatible with code generated
+ without that switch. Use it to conform to a non-default
+ application binary interface. Not all targets provide complete
+ support for this switch.
- gcc -g -fgnu-runtime -O -c some_class.m
+\1f
+File: gcc.info, Node: Environment Variables, Next: Running Protoize, Prev: Code Gen Options, Up: Invoking GCC
+
+3.19 Environment Variables Affecting GCC
+========================================
+
+This section describes several environment variables that affect how GCC
+operates. Some of them work by specifying directories or prefixes to
+use when searching for various kinds of files. Some are used to
+specify other aspects of the compilation environment.
+
+ Note that you can also specify places to search using options such as
+`-B', `-I' and `-L' (*note Directory Options::). These take precedence
+over places specified using environment variables, which in turn take
+precedence over those specified by the configuration of GCC. *Note
+Controlling the Compilation Driver `gcc': (gccint)Driver.
+
+`LANG'
+`LC_CTYPE'
+`LC_MESSAGES'
+`LC_ALL'
+ These environment variables control the way that GCC uses
+ localization information that allow GCC to work with different
+ national conventions. GCC inspects the locale categories
+ `LC_CTYPE' and `LC_MESSAGES' if it has been configured to do so.
+ These locale categories can be set to any value supported by your
+ installation. A typical value is `en_UK' for English in the United
+ Kingdom.
+
+ The `LC_CTYPE' environment variable specifies character
+ classification. GCC uses it to determine the character boundaries
+ in a string; this is needed for some multibyte encodings that
+ contain quote and escape characters that would otherwise be
+ interpreted as a string end or escape.
+
+ The `LC_MESSAGES' environment variable specifies the language to
+ use in diagnostic messages.
+
+ If the `LC_ALL' environment variable is set, it overrides the value
+ of `LC_CTYPE' and `LC_MESSAGES'; otherwise, `LC_CTYPE' and
+ `LC_MESSAGES' default to the value of the `LANG' environment
+ variable. If none of these variables are set, GCC defaults to
+ traditional C English behavior.
+
+`TMPDIR'
+ If `TMPDIR' is set, it specifies the directory to use for temporary
+ files. GCC uses temporary files to hold the output of one stage of
+ compilation which is to be used as input to the next stage: for
+ example, the output of the preprocessor, which is the input to the
+ compiler proper.
+
+`GCC_EXEC_PREFIX'
+ If `GCC_EXEC_PREFIX' is set, it specifies a prefix to use in the
+ names of the subprograms executed by the compiler. No slash is
+ added when this prefix is combined with the name of a subprogram,
+ but you can specify a prefix that ends with a slash if you wish.
+
+ If `GCC_EXEC_PREFIX' is not set, GCC will attempt to figure out an
+ appropriate prefix to use based on the pathname it was invoked
+ with.
+
+ If GCC cannot find the subprogram using the specified prefix, it
+ tries looking in the usual places for the subprogram.
+
+ The default value of `GCC_EXEC_PREFIX' is `PREFIX/lib/gcc-lib/'
+ where PREFIX is the value of `prefix' when you ran the `configure'
+ script.
+
+ Other prefixes specified with `-B' take precedence over this
+ prefix.
+
+ This prefix is also used for finding files such as `crt0.o' that
+ are used for linking.
+
+ In addition, the prefix is used in an unusual way in finding the
+ directories to search for header files. For each of the standard
+ directories whose name normally begins with
+ `/usr/local/lib/gcc-lib' (more precisely, with the value of
+ `GCC_INCLUDE_DIR'), GCC tries replacing that beginning with the
+ specified prefix to produce an alternate directory name. Thus,
+ with `-Bfoo/', GCC will search `foo/bar' where it would normally
+ search `/usr/local/lib/bar'. These alternate directories are
+ searched first; the standard directories come next.
+
+`COMPILER_PATH'
+ The value of `COMPILER_PATH' is a colon-separated list of
+ directories, much like `PATH'. GCC tries the directories thus
+ specified when searching for subprograms, if it can't find the
+ subprograms using `GCC_EXEC_PREFIX'.
+
+`LIBRARY_PATH'
+ The value of `LIBRARY_PATH' is a colon-separated list of
+ directories, much like `PATH'. When configured as a native
+ compiler, GCC tries the directories thus specified when searching
+ for special linker files, if it can't find them using
+ `GCC_EXEC_PREFIX'. Linking using GCC also uses these directories
+ when searching for ordinary libraries for the `-l' option (but
+ directories specified with `-L' come first).
+
+`LANG'
+ This variable is used to pass locale information to the compiler.
+ One way in which this information is used is to determine the
+ character set to be used when character literals, string literals
+ and comments are parsed in C and C++. When the compiler is
+ configured to allow multibyte characters, the following values for
+ `LANG' are recognized:
+
+ `C-JIS'
+ Recognize JIS characters.
+
+ `C-SJIS'
+ Recognize SJIS characters.
+
+ `C-EUCJP'
+ Recognize EUCJP characters.
+
+ If `LANG' is not defined, or if it has some other value, then the
+ compiler will use mblen and mbtowc as defined by the default
+ locale to recognize and translate multibyte characters.
+
+Some additional environments variables affect the behavior of the
+preprocessor.
+
+`CPATH'
+`C_INCLUDE_PATH'
+`CPLUS_INCLUDE_PATH'
+`OBJC_INCLUDE_PATH'
+ Each variable's value is a list of directories separated by a
+ special character, much like `PATH', in which to look for header
+ files. The special character, `PATH_SEPARATOR', is
+ target-dependent and determined at GCC build time. For
+ Windows-based targets it is a semicolon, and for almost all other
+ targets it is a colon.
+
+ `CPATH' specifies a list of directories to be searched as if
+ specified with `-I', but after any paths given with `-I' options
+ on the command line. The environment variable is used regardless
+ of which language is being preprocessed.
+
+ The remaining environment variables apply only when preprocessing
+ the particular language indicated. Each specifies a list of
+ directories to be searched as if specified with `-isystem', but
+ after any paths given with `-isystem' options on the command line.
+
+`DEPENDENCIES_OUTPUT'
+ If this variable is set, its value specifies how to output
+ dependencies for Make based on the non-system header files
+ processed by the compiler. System header files are ignored in the
+ dependency output.
+
+ The value of `DEPENDENCIES_OUTPUT' can be just a file name, in
+ which case the Make rules are written to that file, guessing the
+ target name from the source file name. Or the value can have the
+ form `FILE TARGET', in which case the rules are written to file
+ FILE using TARGET as the target name.
+
+ In other words, this environment variable is equivalent to
+ combining the options `-MM' and `-MF' (*note Preprocessor
+ Options::), with an optional `-MT' switch too.
+
+`SUNPRO_DEPENDENCIES'
+ This variable is the same as the environment variable
+ `DEPENDENCIES_OUTPUT' (*note DEPENDENCIES_OUTPUT::), except that
+ system header files are not ignored, so it implies `-M' rather
+ than `-MM'. However, the dependence on the main input file is
+ omitted. *Note Preprocessor Options::.
-In this example, only `-fgnu-runtime' is an option meant only for
-Objective-C programs; you can use the other options with any language
-supported by GCC.
+\1f
+File: gcc.info, Node: Running Protoize, Prev: Environment Variables, Up: Invoking GCC
+
+3.20 Running Protoize
+=====================
+
+The program `protoize' is an optional part of GCC. You can use it to
+add prototypes to a program, thus converting the program to ISO C in
+one respect. The companion program `unprotoize' does the reverse: it
+removes argument types from any prototypes that are found.
+
+ When you run these programs, you must specify a set of source files
+as command line arguments. The conversion programs start out by
+compiling these files to see what functions they define. The
+information gathered about a file FOO is saved in a file named `FOO.X'.
+
+ After scanning comes actual conversion. The specified files are all
+eligible to be converted; any files they include (whether sources or
+just headers) are eligible as well.
+
+ But not all the eligible files are converted. By default,
+`protoize' and `unprotoize' convert only source and header files in the
+current directory. You can specify additional directories whose files
+should be converted with the `-d DIRECTORY' option. You can also
+specify particular files to exclude with the `-x FILE' option. A file
+is converted if it is eligible, its directory name matches one of the
+specified directory names, and its name within the directory has not
+been excluded.
+
+ Basic conversion with `protoize' consists of rewriting most function
+definitions and function declarations to specify the types of the
+arguments. The only ones not rewritten are those for varargs functions.
+
+ `protoize' optionally inserts prototype declarations at the
+beginning of the source file, to make them available for any calls that
+precede the function's definition. Or it can insert prototype
+declarations with block scope in the blocks where undeclared functions
+are called.
+
+ Basic conversion with `unprotoize' consists of rewriting most
+function declarations to remove any argument types, and rewriting
+function definitions to the old-style pre-ISO form.
+
+ Both conversion programs print a warning for any function
+declaration or definition that they can't convert. You can suppress
+these warnings with `-q'.
+
+ The output from `protoize' or `unprotoize' replaces the original
+source file. The original file is renamed to a name ending with
+`.save' (for DOS, the saved filename ends in `.sav' without the
+original `.c' suffix). If the `.save' (`.sav' for DOS) file already
+exists, then the source file is simply discarded.
+
+ `protoize' and `unprotoize' both depend on GCC itself to scan the
+program and collect information about the functions it uses. So
+neither of these programs will work until GCC is installed.
+
+ Here is a table of the options you can use with `protoize' and
+`unprotoize'. Each option works with both programs unless otherwise
+stated.
+
+`-B DIRECTORY'
+ Look for the file `SYSCALLS.c.X' in DIRECTORY, instead of the
+ usual directory (normally `/usr/local/lib'). This file contains
+ prototype information about standard system functions. This option
+ applies only to `protoize'.
+
+`-c COMPILATION-OPTIONS'
+ Use COMPILATION-OPTIONS as the options when running `gcc' to
+ produce the `.X' files. The special option `-aux-info' is always
+ passed in addition, to tell `gcc' to write a `.X' file.
+
+ Note that the compilation options must be given as a single
+ argument to `protoize' or `unprotoize'. If you want to specify
+ several `gcc' options, you must quote the entire set of
+ compilation options to make them a single word in the shell.
+
+ There are certain `gcc' arguments that you cannot use, because they
+ would produce the wrong kind of output. These include `-g', `-O',
+ `-c', `-S', and `-o' If you include these in the
+ COMPILATION-OPTIONS, they are ignored.
+
+`-C'
+ Rename files to end in `.C' (`.cc' for DOS-based file systems)
+ instead of `.c'. This is convenient if you are converting a C
+ program to C++. This option applies only to `protoize'.
+
+`-g'
+ Add explicit global declarations. This means inserting explicit
+ declarations at the beginning of each source file for each function
+ that is called in the file and was not declared. These
+ declarations precede the first function definition that contains a
+ call to an undeclared function. This option applies only to
+ `protoize'.
+
+`-i STRING'
+ Indent old-style parameter declarations with the string STRING.
+ This option applies only to `protoize'.
+
+ `unprotoize' converts prototyped function definitions to old-style
+ function definitions, where the arguments are declared between the
+ argument list and the initial `{'. By default, `unprotoize' uses
+ five spaces as the indentation. If you want to indent with just
+ one space instead, use `-i " "'.
+
+`-k'
+ Keep the `.X' files. Normally, they are deleted after conversion
+ is finished.
+
+`-l'
+ Add explicit local declarations. `protoize' with `-l' inserts a
+ prototype declaration for each function in each block which calls
+ the function without any declaration. This option applies only to
+ `protoize'.
+
+`-n'
+ Make no real changes. This mode just prints information about the
+ conversions that would have been done without `-n'.
+
+`-N'
+ Make no `.save' files. The original files are simply deleted.
+ Use this option with caution.
+
+`-p PROGRAM'
+ Use the program PROGRAM as the compiler. Normally, the name `gcc'
+ is used.
+
+`-q'
+ Work quietly. Most warnings are suppressed.
+
+`-v'
+ Print the version number, just like `-v' for `gcc'.
+
+ If you need special compiler options to compile one of your program's
+source files, then you should generate that file's `.X' file specially,
+by running `gcc' on that source file with the appropriate options and
+the option `-aux-info'. Then run `protoize' on the entire set of
+files. `protoize' will use the existing `.X' file because it is newer
+than the source file. For example:
+
+ gcc -Dfoo=bar file1.c -aux-info file1.X
+ protoize *.c
+
+You need to include the special files along with the rest in the
+`protoize' command, even though their `.X' files already exist, because
+otherwise they won't get converted.
+
+ *Note Protoize Caveats::, for more information on how to use
+`protoize' successfully.
- Here is a list of options that are _only_ for compiling Objective-C
-programs:
+\1f
+File: gcc.info, Node: C Implementation, Next: C Extensions, Prev: Invoking GCC, Up: Top
+
+4 C Implementation-defined behavior
+***********************************
+
+A conforming implementation of ISO C is required to document its choice
+of behavior in each of the areas that are designated "implementation
+defined." The following lists all such areas, along with the section
+number from the ISO/IEC 9899:1999 standard.
+
+* Menu:
+
+* Translation implementation::
+* Environment implementation::
+* Identifiers implementation::
+* Characters implementation::
+* Integers implementation::
+* Floating point implementation::
+* Arrays and pointers implementation::
+* Hints implementation::
+* Structures unions enumerations and bit-fields implementation::
+* Qualifiers implementation::
+* Preprocessing directives implementation::
+* Library functions implementation::
+* Architecture implementation::
+* Locale-specific behavior implementation::
-`-fconstant-string-class=CLASS-NAME'
- Use CLASS-NAME as the name of the class to instantiate for each
- literal string specified with the syntax `@"..."'. The default
- class name is `NXConstantString'.
+\1f
+File: gcc.info, Node: Translation implementation, Next: Environment implementation, Up: C Implementation
-`-fgnu-runtime'
- Generate object code compatible with the standard GNU Objective-C
- runtime. This is the default for most types of systems.
+4.1 Translation
+===============
-`-fnext-runtime'
- Generate output compatible with the NeXT runtime. This is the
- default for NeXT-based systems, including Darwin and Mac OS X.
+ * `How a diagnostic is identified (3.10, 5.1.1.3).'
-`-gen-decls'
- Dump interface declarations for all classes seen in the source
- file to a file named `SOURCENAME.decl'.
+ * `Whether each nonempty sequence of white-space characters other
+ than new-line is retained or replaced by one space character in
+ translation phase 3 (5.1.1.2).'
-`-Wno-protocol'
- Do not warn if methods required by a protocol are not implemented
- in the class adopting it.
+\1f
+File: gcc.info, Node: Environment implementation, Next: Identifiers implementation, Prev: Translation implementation, Up: C Implementation
-`-Wselector'
- Warn if a selector has multiple methods of different types defined.
+4.2 Environment
+===============
+The behavior of these points are dependent on the implementation of the
+C library, and are not defined by GCC itself.
\1f
-File: gcc.info, Node: Language Independent Options, Next: Warning Options, Prev: Objective-C Dialect Options, Up: Invoking GCC
+File: gcc.info, Node: Identifiers implementation, Next: Characters implementation, Prev: Environment implementation, Up: C Implementation
-Options to Control Diagnostic Messages Formatting
-=================================================
+4.3 Identifiers
+===============
+
+ * `Which additional multibyte characters may appear in identifiers
+ and their correspondence to universal character names (6.4.2).'
+
+ * `The number of significant initial characters in an identifier
+ (5.2.4.1, 6.4.2).'
+
+\1f
+File: gcc.info, Node: Characters implementation, Next: Integers implementation, Prev: Identifiers implementation, Up: C Implementation
+
+4.4 Characters
+==============
+
+ * `The number of bits in a byte (3.6).'
+
+ * `The values of the members of the execution character set (5.2.1).'
+
+ * `The unique value of the member of the execution character set
+ produced for each of the standard alphabetic escape sequences
+ (5.2.2).'
+
+ * `The value of a `char' object into which has been stored any
+ character other than a member of the basic execution character set
+ (6.2.5).'
+
+ * `Which of `signed char' or `unsigned char' has the same range,
+ representation, and behavior as "plain" `char' (6.2.5, 6.3.1.1).'
+
+ * `The mapping of members of the source character set (in character
+ constants and string literals) to members of the execution
+ character set (6.4.4.4, 5.1.1.2).'
+
+ * `The value of an integer character constant containing more than
+ one character or containing a character or escape sequence that
+ does not map to a single-byte execution character (6.4.4.4).'
+
+ * `The value of a wide character constant containing more than one
+ multibyte character, or containing a multibyte character or escape
+ sequence not represented in the extended execution character set
+ (6.4.4.4).'
+
+ * `The current locale used to convert a wide character constant
+ consisting of a single multibyte character that maps to a member
+ of the extended execution character set into a corresponding wide
+ character code (6.4.4.4).'
+
+ * `The current locale used to convert a wide string literal into
+ corresponding wide character codes (6.4.5).'
+
+ * `The value of a string literal containing a multibyte character or
+ escape sequence not represented in the execution character set
+ (6.4.5).'
+
+\1f
+File: gcc.info, Node: Integers implementation, Next: Floating point implementation, Prev: Characters implementation, Up: C Implementation
+
+4.5 Integers
+============
+
+ * `Any extended integer types that exist in the implementation
+ (6.2.5).'
+
+ * `Whether signed integer types are represented using sign and
+ magnitude, two's complement, or one's complement, and whether the
+ extraordinary value is a trap representation or an ordinary value
+ (6.2.6.2).'
+
+ * `The rank of any extended integer type relative to another extended
+ integer type with the same precision (6.3.1.1).'
+
+ * `The result of, or the signal raised by, converting an integer to a
+ signed integer type when the value cannot be represented in an
+ object of that type (6.3.1.3).'
+
+ * `The results of some bitwise operations on signed integers (6.5).'
+
+\1f
+File: gcc.info, Node: Floating point implementation, Next: Arrays and pointers implementation, Prev: Integers implementation, Up: C Implementation
+
+4.6 Floating point
+==================
+
+ * `The accuracy of the floating-point operations and of the library
+ functions in `<math.h>' and `<complex.h>' that return
+ floating-point results (5.2.4.2.2).'
+
+ * `The rounding behaviors characterized by non-standard values of
+ `FLT_ROUNDS' (5.2.4.2.2).'
+
+ * `The evaluation methods characterized by non-standard negative
+ values of `FLT_EVAL_METHOD' (5.2.4.2.2).'
+
+ * `The direction of rounding when an integer is converted to a
+ floating-point number that cannot exactly represent the original
+ value (6.3.1.4).'
+
+ * `The direction of rounding when a floating-point number is
+ converted to a narrower floating-point number (6.3.1.5).'
+
+ * `How the nearest representable value or the larger or smaller
+ representable value immediately adjacent to the nearest
+ representable value is chosen for certain floating constants
+ (6.4.4.2).'
+
+ * `Whether and how floating expressions are contracted when not
+ disallowed by the `FP_CONTRACT' pragma (6.5).'
+
+ * `The default state for the `FENV_ACCESS' pragma (7.6.1).'
+
+ * `Additional floating-point exceptions, rounding modes,
+ environments, and classifications, and their macro names (7.6,
+ 7.12).'
+
+ * `The default state for the `FP_CONTRACT' pragma (7.12.2).'
+
+ * `Whether the "inexact" floating-point exception can be raised when
+ the rounded result actually does equal the mathematical result in
+ an IEC 60559 conformant implementation (F.9).'
+
+ * `Whether the "underflow" (and "inexact") floating-point exception
+ can be raised when a result is tiny but not inexact in an IEC
+ 60559 conformant implementation (F.9).'
+
+
+\1f
+File: gcc.info, Node: Arrays and pointers implementation, Next: Hints implementation, Prev: Floating point implementation, Up: C Implementation
+
+4.7 Arrays and pointers
+=======================
+
+ * `The result of converting a pointer to an integer or vice versa
+ (6.3.2.3).'
+
+ A cast from pointer to integer discards most-significant bits if
+ the pointer representation is larger than the integer type,
+ sign-extends(1) if the pointer representation is smaller than the
+ integer type, otherwise the bits are unchanged.
+
+ A cast from integer to pointer discards most-significant bits if
+ the pointer representation is smaller than the integer type,
+ extends according to the signedness of the integer type if the
+ pointer representation is larger than the integer type, otherwise
+ the bits are unchanged.
+
+ When casting from pointer to integer and back again, the resulting
+ pointer must reference the same object as the original pointer,
+ otherwise the behavior is undefined. That is, one may not use
+ integer arithmetic to avoid the undefined behavior of pointer
+ arithmetic as proscribed in 6.5.6/8.
+
+ * `The size of the result of subtracting two pointers to elements of
+ the same array (6.5.6).'
+
+
+ ---------- Footnotes ----------
+
+ (1) Future versions of GCC may zero-extend, or use a target-defined
+`ptr_extend' pattern. Do not rely on sign extension.
+
+\1f
+File: gcc.info, Node: Hints implementation, Next: Structures unions enumerations and bit-fields implementation, Prev: Arrays and pointers implementation, Up: C Implementation
+
+4.8 Hints
+=========
+
+ * `The extent to which suggestions made by using the `register'
+ storage-class specifier are effective (6.7.1).'
+
+ * `The extent to which suggestions made by using the inline function
+ specifier are effective (6.7.4).'
+
+
+\1f
+File: gcc.info, Node: Structures unions enumerations and bit-fields implementation, Next: Qualifiers implementation, Prev: Hints implementation, Up: C Implementation
+
+4.9 Structures, unions, enumerations, and bit-fields
+====================================================
+
+ * `Whether a "plain" int bit-field is treated as a `signed int'
+ bit-field or as an `unsigned int' bit-field (6.7.2, 6.7.2.1).'
+
+ * `Allowable bit-field types other than `_Bool', `signed int', and
+ `unsigned int' (6.7.2.1).'
+
+ * `Whether a bit-field can straddle a storage-unit boundary
+ (6.7.2.1).'
+
+ * `The order of allocation of bit-fields within a unit (6.7.2.1).'
+
+ * `The alignment of non-bit-field members of structures (6.7.2.1).'
+
+ * `The integer type compatible with each enumerated type (6.7.2.2).'
+
+
+\1f
+File: gcc.info, Node: Qualifiers implementation, Next: Preprocessing directives implementation, Prev: Structures unions enumerations and bit-fields implementation, Up: C Implementation
+
+4.10 Qualifiers
+===============
+
+ * `What constitutes an access to an object that has
+ volatile-qualified type (6.7.3).'
+
+
+\1f
+File: gcc.info, Node: Preprocessing directives implementation, Next: Library functions implementation, Prev: Qualifiers implementation, Up: C Implementation
+
+4.11 Preprocessing directives
+=============================
+
+ * `How sequences in both forms of header names are mapped to headers
+ or external source file names (6.4.7).'
+
+ * `Whether the value of a character constant in a constant expression
+ that controls conditional inclusion matches the value of the same
+ character constant in the execution character set (6.10.1).'
+
+ * `Whether the value of a single-character character constant in a
+ constant expression that controls conditional inclusion may have a
+ negative value (6.10.1).'
+
+ * `The places that are searched for an included `<>' delimited
+ header, and how the places are specified or the header is
+ identified (6.10.2).'
+
+ * `How the named source file is searched for in an included `""'
+ delimited header (6.10.2).'
+
+ * `The method by which preprocessing tokens (possibly resulting from
+ macro expansion) in a `#include' directive are combined into a
+ header name (6.10.2).'
+
+ * `The nesting limit for `#include' processing (6.10.2).'
+
+ * `Whether the `#' operator inserts a `\' character before the `\'
+ character that begins a universal character name in a character
+ constant or string literal (6.10.3.2).'
+
+ * `The behavior on each recognized non-`STDC #pragma' directive
+ (6.10.6).'
+
+ * `The definitions for `__DATE__' and `__TIME__' when respectively,
+ the date and time of translation are not available (6.10.8).'
+
+
+\1f
+File: gcc.info, Node: Library functions implementation, Next: Architecture implementation, Prev: Preprocessing directives implementation, Up: C Implementation
+
+4.12 Library functions
+======================
+
+The behavior of these points are dependent on the implementation of the
+C library, and are not defined by GCC itself.
+
+\1f
+File: gcc.info, Node: Architecture implementation, Next: Locale-specific behavior implementation, Prev: Library functions implementation, Up: C Implementation
+
+4.13 Architecture
+=================
+
+ * `The values or expressions assigned to the macros specified in the
+ headers `<float.h>', `<limits.h>', and `<stdint.h>' (5.2.4.2,
+ 7.18.2, 7.18.3).'
+
+ * `The number, order, and encoding of bytes in any object (when not
+ explicitly specified in this International Standard) (6.2.6.1).'
+
+ * `The value of the result of the sizeof operator (6.5.3.4).'
+
+
+\1f
+File: gcc.info, Node: Locale-specific behavior implementation, Prev: Architecture implementation, Up: C Implementation
+
+4.14 Locale-specific behavior
+=============================
+
+The behavior of these points are dependent on the implementation of the
+C library, and are not defined by GCC itself.
+
+\1f
+File: gcc.info, Node: C Extensions, Next: C++ Extensions, Prev: C Implementation, Up: Top
+
+5 Extensions to the C Language Family
+*************************************
+
+GNU C provides several language features not found in ISO standard C.
+(The `-pedantic' option directs GCC to print a warning message if any
+of these features is used.) To test for the availability of these
+features in conditional compilation, check for a predefined macro
+`__GNUC__', which is always defined under GCC.
+
+ These extensions are available in C and Objective-C. Most of them
+are also available in C++. *Note Extensions to the C++ Language: C++
+Extensions, for extensions that apply _only_ to C++.
+
+ Some features that are in ISO C99 but not C89 or C++ are also, as
+extensions, accepted by GCC in C89 mode and in C++.
+
+* Menu:
+
+* Statement Exprs:: Putting statements and declarations inside expressions.
+* Local Labels:: Labels local to a statement-expression.
+* Labels as Values:: Getting pointers to labels, and computed gotos.
+* Nested Functions:: As in Algol and Pascal, lexical scoping of functions.
+* Constructing Calls:: Dispatching a call to another function.
+* Typeof:: `typeof': referring to the type of an expression.
+* Lvalues:: Using `?:', `,' and casts in lvalues.
+* Conditionals:: Omitting the middle operand of a `?:' expression.
+* Long Long:: Double-word integers---`long long int'.
+* Complex:: Data types for complex numbers.
+* Hex Floats:: Hexadecimal floating-point constants.
+* Zero Length:: Zero-length arrays.
+* Variable Length:: Arrays whose length is computed at run time.
+* Variadic Macros:: Macros with a variable number of arguments.
+* Escaped Newlines:: Slightly looser rules for escaped newlines.
+* Multi-line Strings:: String literals with embedded newlines.
+* Subscripting:: Any array can be subscripted, even if not an lvalue.
+* Pointer Arith:: Arithmetic on `void'-pointers and function pointers.
+* Initializers:: Non-constant initializers.
+* Compound Literals:: Compound literals give structures, unions
+ or arrays as values.
+* Designated Inits:: Labeling elements of initializers.
+* Cast to Union:: Casting to union type from any member of the union.
+* Case Ranges:: `case 1 ... 9' and such.
+* Mixed Declarations:: Mixing declarations and code.
+* Function Attributes:: Declaring that functions have no side effects,
+ or that they can never return.
+* Attribute Syntax:: Formal syntax for attributes.
+* Function Prototypes:: Prototype declarations and old-style definitions.
+* C++ Comments:: C++ comments are recognized.
+* Dollar Signs:: Dollar sign is allowed in identifiers.
+* Character Escapes:: `\e' stands for the character <ESC>.
+* Variable Attributes:: Specifying attributes of variables.
+* Type Attributes:: Specifying attributes of types.
+* Alignment:: Inquiring about the alignment of a type or variable.
+* Inline:: Defining inline functions (as fast as macros).
+* Extended Asm:: Assembler instructions with C expressions as operands.
+ (With them you can define ``built-in'' functions.)
+* Constraints:: Constraints for asm operands
+* Asm Labels:: Specifying the assembler name to use for a C symbol.
+* Explicit Reg Vars:: Defining variables residing in specified registers.
+* Alternate Keywords:: `__const__', `__asm__', etc., for header files.
+* Incomplete Enums:: `enum foo;', with details to follow.
+* Function Names:: Printable strings which are the name of the current
+ function.
+* Return Address:: Getting the return or frame address of a function.
+* Vector Extensions:: Using vector instructions through built-in functions.
+* Other Builtins:: Other built-in functions.
+* Target Builtins:: Built-in functions specific to particular targets.
+* Pragmas:: Pragmas accepted by GCC.
+* Unnamed Fields:: Unnamed struct/union fields within structs/unions.
+
+\1f
+File: gcc.info, Node: Statement Exprs, Next: Local Labels, Up: C Extensions
+
+5.1 Statements and Declarations in Expressions
+==============================================
+
+A compound statement enclosed in parentheses may appear as an expression
+in GNU C. This allows you to use loops, switches, and local variables
+within an expression.
+
+ Recall that a compound statement is a sequence of statements
+surrounded by braces; in this construct, parentheses go around the
+braces. For example:
+
+ ({ int y = foo (); int z;
+ if (y > 0) z = y;
+ else z = - y;
+ z; })
+
+is a valid (though slightly more complex than necessary) expression for
+the absolute value of `foo ()'.
+
+ The last thing in the compound statement should be an expression
+followed by a semicolon; the value of this subexpression serves as the
+value of the entire construct. (If you use some other kind of statement
+last within the braces, the construct has type `void', and thus
+effectively no value.)
- Traditionally, diagnostic messages have been formatted irrespective
-of the output device's aspect (e.g. its width, ...). The options
-described below can be used to control the diagnostic messages
-formatting algorithm, e.g. how many characters per line, how often
-source location information should be reported. Right now, only the
-C++ front end can honor these options. However it is expected, in the
-near future, that the remaining front ends would be able to digest them
-correctly.
-
-`-fmessage-length=N'
- Try to format error messages so that they fit on lines of about N
- characters. The default is 72 characters for `g++' and 0 for the
- rest of the front ends supported by GCC. If N is zero, then no
- line-wrapping will be done; each error message will appear on a
- single line.
-
-`-fdiagnostics-show-location=once'
- Only meaningful in line-wrapping mode. Instructs the diagnostic
- messages reporter to emit _once_ source location information; that
- is, in case the message is too long to fit on a single physical
- line and has to be wrapped, the source location won't be emitted
- (as prefix) again, over and over, in subsequent continuation
- lines. This is the default behavior.
-
-`-fdiagnostics-show-location=every-line'
- Only meaningful in line-wrapping mode. Instructs the diagnostic
- messages reporter to emit the same source location information (as
- prefix) for physical lines that result from the process of breaking
- a message which is too long to fit on a single line.
+ This feature is especially useful in making macro definitions "safe"
+(so that they evaluate each operand exactly once). For example, the
+"maximum" function is commonly defined as a macro in standard C as
+follows:
+ #define max(a,b) ((a) > (b) ? (a) : (b))
+
+But this definition computes either A or B twice, with bad results if
+the operand has side effects. In GNU C, if you know the type of the
+operands (here let's assume `int'), you can define the macro safely as
+follows:
+
+ #define maxint(a,b) \
+ ({int _a = (a), _b = (b); _a > _b ? _a : _b; })
+
+ Embedded statements are not allowed in constant expressions, such as
+the value of an enumeration constant, the width of a bit-field, or the
+initial value of a static variable.
+
+ If you don't know the type of the operand, you can still do this,
+but you must use `typeof' (*note Typeof::).
+
+ Statement expressions are not supported fully in G++, and their fate
+there is unclear. (It is possible that they will become fully supported
+at some point, or that they will be deprecated, or that the bugs that
+are present will continue to exist indefinitely.) Presently, statement
+expressions do not work well as default arguments.
+
+ In addition, there are semantic issues with statement-expressions in
+C++. If you try to use statement-expressions instead of inline
+functions in C++, you may be surprised at the way object destruction is
+handled. For example:
+
+ #define foo(a) ({int b = (a); b + 3; })
+
+does not work the same way as:
+
+ inline int foo(int a) { int b = a; return b + 3; }
+
+In particular, if the expression passed into `foo' involves the
+creation of temporaries, the destructors for those temporaries will be
+run earlier in the case of the macro than in the case of the function.
+
+ These considerations mean that it is probably a bad idea to use
+statement-expressions of this form in header files that are designed to
+work with C++. (Note that some versions of the GNU C Library contained
+header files using statement-expression that lead to precisely this
+bug.)
+
+\1f
+File: gcc.info, Node: Local Labels, Next: Labels as Values, Prev: Statement Exprs, Up: C Extensions
+
+5.2 Locally Declared Labels
+===========================
+
+Each statement expression is a scope in which "local labels" can be
+declared. A local label is simply an identifier; you can jump to it
+with an ordinary `goto' statement, but only from within the statement
+expression it belongs to.
+
+ A local label declaration looks like this:
+
+ __label__ LABEL;
+
+or
+
+ __label__ LABEL1, LABEL2, ...;
+
+ Local label declarations must come at the beginning of the statement
+expression, right after the `({', before any ordinary declarations.
+
+ The label declaration defines the label _name_, but does not define
+the label itself. You must do this in the usual way, with `LABEL:',
+within the statements of the statement expression.
+
+ The local label feature is useful because statement expressions are
+often used in macros. If the macro contains nested loops, a `goto' can
+be useful for breaking out of them. However, an ordinary label whose
+scope is the whole function cannot be used: if the macro can be
+expanded several times in one function, the label will be multiply
+defined in that function. A local label avoids this problem. For
+example:
+
+ #define SEARCH(array, target) \
+ ({ \
+ __label__ found; \
+ typeof (target) _SEARCH_target = (target); \
+ typeof (*(array)) *_SEARCH_array = (array); \
+ int i, j; \
+ int value; \
+ for (i = 0; i < max; i++) \
+ for (j = 0; j < max; j++) \
+ if (_SEARCH_array[i][j] == _SEARCH_target) \
+ { value = i; goto found; } \
+ value = -1; \
+ found: \
+ value; \
+ })
+
+\1f
+File: gcc.info, Node: Labels as Values, Next: Nested Functions, Prev: Local Labels, Up: C Extensions
+
+5.3 Labels as Values
+====================
+
+You can get the address of a label defined in the current function (or
+a containing function) with the unary operator `&&'. The value has
+type `void *'. This value is a constant and can be used wherever a
+constant of that type is valid. For example:
+
+ void *ptr;
+ ...
+ ptr = &&foo;
+
+ To use these values, you need to be able to jump to one. This is
+done with the computed goto statement(1), `goto *EXP;'. For example,
+
+ goto *ptr;
+
+Any expression of type `void *' is allowed.
+
+ One way of using these constants is in initializing a static array
+that will serve as a jump table:
+
+ static void *array[] = { &&foo, &&bar, &&hack };
+
+ Then you can select a label with indexing, like this:
+
+ goto *array[i];
+
+Note that this does not check whether the subscript is in bounds--array
+indexing in C never does that.
+
+ Such an array of label values serves a purpose much like that of the
+`switch' statement. The `switch' statement is cleaner, so use that
+rather than an array unless the problem does not fit a `switch'
+statement very well.
+
+ Another use of label values is in an interpreter for threaded code.
+The labels within the interpreter function can be stored in the
+threaded code for super-fast dispatching.
+
+ You may not use this mechanism to jump to code in a different
+function. If you do that, totally unpredictable things will happen.
+The best way to avoid this is to store the label address only in
+automatic variables and never pass it as an argument.
+
+ An alternate way to write the above example is
+
+ static const int array[] = { &&foo - &&foo, &&bar - &&foo,
+ &&hack - &&foo };
+ goto *(&&foo + array[i]);
+
+This is more friendly to code living in shared libraries, as it reduces
+the number of dynamic relocations that are needed, and by consequence,
+allows the data to be read-only.
+
+ ---------- Footnotes ----------
+
+ (1) The analogous feature in Fortran is called an assigned goto, but
+that name seems inappropriate in C, where one can do more than simply
+store label addresses in label variables.
+
+\1f
+File: gcc.info, Node: Nested Functions, Next: Constructing Calls, Prev: Labels as Values, Up: C Extensions
+
+5.4 Nested Functions
+====================
+
+A "nested function" is a function defined inside another function.
+(Nested functions are not supported for GNU C++.) The nested function's
+name is local to the block where it is defined. For example, here we
+define a nested function named `square', and call it twice:
+
+ foo (double a, double b)
+ {
+ double square (double z) { return z * z; }
+
+ return square (a) + square (b);
+ }
+
+ The nested function can access all the variables of the containing
+function that are visible at the point of its definition. This is
+called "lexical scoping". For example, here we show a nested function
+which uses an inherited variable named `offset':
+
+ bar (int *array, int offset, int size)
+ {
+ int access (int *array, int index)
+ { return array[index + offset]; }
+ int i;
+ ...
+ for (i = 0; i < size; i++)
+ ... access (array, i) ...
+ }
+
+ Nested function definitions are permitted within functions in the
+places where variable definitions are allowed; that is, in any block,
+before the first statement in the block.
+
+ It is possible to call the nested function from outside the scope of
+its name by storing its address or passing the address to another
+function:
+
+ hack (int *array, int size)
+ {
+ void store (int index, int value)
+ { array[index] = value; }
+
+ intermediate (store, size);
+ }
+
+ Here, the function `intermediate' receives the address of `store' as
+an argument. If `intermediate' calls `store', the arguments given to
+`store' are used to store into `array'. But this technique works only
+so long as the containing function (`hack', in this example) does not
+exit.
+
+ If you try to call the nested function through its address after the
+containing function has exited, all hell will break loose. If you try
+to call it after a containing scope level has exited, and if it refers
+to some of the variables that are no longer in scope, you may be lucky,
+but it's not wise to take the risk. If, however, the nested function
+does not refer to anything that has gone out of scope, you should be
+safe.
+
+ GCC implements taking the address of a nested function using a
+technique called "trampolines". A paper describing them is available as
+
+`http://people.debian.org/~aaronl/Usenix88-lexic.pdf'.
+
+ A nested function can jump to a label inherited from a containing
+function, provided the label was explicitly declared in the containing
+function (*note Local Labels::). Such a jump returns instantly to the
+containing function, exiting the nested function which did the `goto'
+and any intermediate functions as well. Here is an example:
+
+ bar (int *array, int offset, int size)
+ {
+ __label__ failure;
+ int access (int *array, int index)
+ {
+ if (index > size)
+ goto failure;
+ return array[index + offset];
+ }
+ int i;
+ ...
+ for (i = 0; i < size; i++)
+ ... access (array, i) ...
+ ...
+ return 0;
+
+ /* Control comes here from `access'
+ if it detects an error. */
+ failure:
+ return -1;
+ }
+
+ A nested function always has internal linkage. Declaring one with
+`extern' is erroneous. If you need to declare the nested function
+before its definition, use `auto' (which is otherwise meaningless for
+function declarations).
+
+ bar (int *array, int offset, int size)
+ {
+ __label__ failure;
+ auto int access (int *, int);
+ ...
+ int access (int *array, int index)
+ {
+ if (index > size)
+ goto failure;
+ return array[index + offset];
+ }
+ ...
+ }
+
+\1f
+File: gcc.info, Node: Constructing Calls, Next: Typeof, Prev: Nested Functions, Up: C Extensions
+
+5.5 Constructing Function Calls
+===============================
+
+Using the built-in functions described below, you can record the
+arguments a function received, and call another function with the same
+arguments, without knowing the number or types of the arguments.
+
+ You can also record the return value of that function call, and
+later return that value, without knowing what data type the function
+tried to return (as long as your caller expects that data type).
+
+ -- Built-in Function: void * __builtin_apply_args ()
+ This built-in function returns a pointer to data describing how to
+ perform a call with the same arguments as were passed to the
+ current function.
+
+ The function saves the arg pointer register, structure value
+ address, and all registers that might be used to pass arguments to
+ a function into a block of memory allocated on the stack. Then it
+ returns the address of that block.
+
+ -- Built-in Function: void * __builtin_apply (void (*FUNCTION)(), void
+ *ARGUMENTS, size_t SIZE)
+ This built-in function invokes FUNCTION with a copy of the
+ parameters described by ARGUMENTS and SIZE.
+
+ The value of ARGUMENTS should be the value returned by
+ `__builtin_apply_args'. The argument SIZE specifies the size of
+ the stack argument data, in bytes.
+
+ This function returns a pointer to data describing how to return
+ whatever value was returned by FUNCTION. The data is saved in a
+ block of memory allocated on the stack.
+
+ It is not always simple to compute the proper value for SIZE. The
+ value is used by `__builtin_apply' to compute the amount of data
+ that should be pushed on the stack and copied from the incoming
+ argument area.
+
+ -- Built-in Function: void __builtin_return (void *RESULT)
+ This built-in function returns the value described by RESULT from
+ the containing function. You should specify, for RESULT, a value
+ returned by `__builtin_apply'.
+
+\1f
+File: gcc.info, Node: Typeof, Next: Lvalues, Prev: Constructing Calls, Up: C Extensions
+
+5.6 Referring to a Type with `typeof'
+=====================================
+
+Another way to refer to the type of an expression is with `typeof'.
+The syntax of using of this keyword looks like `sizeof', but the
+construct acts semantically like a type name defined with `typedef'.
+
+ There are two ways of writing the argument to `typeof': with an
+expression or with a type. Here is an example with an expression:
+
+ typeof (x[0](1))
+
+This assumes that `x' is an array of pointers to functions; the type
+described is that of the values of the functions.
+
+ Here is an example with a typename as the argument:
+
+ typeof (int *)
+
+Here the type described is that of pointers to `int'.
+
+ If you are writing a header file that must work when included in ISO
+C programs, write `__typeof__' instead of `typeof'. *Note Alternate
+Keywords::.
+
+ A `typeof'-construct can be used anywhere a typedef name could be
+used. For example, you can use it in a declaration, in a cast, or
+inside of `sizeof' or `typeof'.
+
+ `typeof' is often useful in conjunction with the
+statements-within-expressions feature. Here is how the two together can
+be used to define a safe "maximum" macro that operates on any
+arithmetic type and evaluates each of its arguments exactly once:
+
+ #define max(a,b) \
+ ({ typeof (a) _a = (a); \
+ typeof (b) _b = (b); \
+ _a > _b ? _a : _b; })
+
+ The reason for using names that start with underscores for the local
+variables is to avoid conflicts with variable names that occur within
+the expressions that are substituted for `a' and `b'. Eventually we
+hope to design a new form of declaration syntax that allows you to
+declare variables whose scopes start only after their initializers;
+this will be a more reliable way to prevent such conflicts.
+
+Some more examples of the use of `typeof':
+
+ * This declares `y' with the type of what `x' points to.
+
+ typeof (*x) y;
+
+ * This declares `y' as an array of such values.
+
+ typeof (*x) y[4];
+
+ * This declares `y' as an array of pointers to characters:
+
+ typeof (typeof (char *)[4]) y;
+
+ It is equivalent to the following traditional C declaration:
+
+ char *y[4];
+
+ To see the meaning of the declaration using `typeof', and why it
+ might be a useful way to write, let's rewrite it with these macros:
+
+ #define pointer(T) typeof(T *)
+ #define array(T, N) typeof(T [N])
+
+ Now the declaration can be rewritten this way:
+
+ array (pointer (char), 4) y;
+
+ Thus, `array (pointer (char), 4)' is the type of arrays of 4
+ pointers to `char'.
+
+ _Compatibility Note:_ In addition to `typeof', GCC 2 supported a
+more limited extension which permitted one to write
+
+ typedef T = EXPR;
+
+with the effect of declaring T to have the type of the expression EXPR.
+This extension does not work with GCC 3 (versions between 3.0 and 3.2
+will crash; 3.2.1 and later give an error). Code which relies on it
+should be rewritten to use `typeof':
+
+ typedef typeof(EXPR) T;
+
+This will work with all versions of GCC.
+
+\1f
+File: gcc.info, Node: Lvalues, Next: Conditionals, Prev: Typeof, Up: C Extensions
+
+5.7 Generalized Lvalues
+=======================
+
+Compound expressions, conditional expressions and casts are allowed as
+lvalues provided their operands are lvalues. This means that you can
+take their addresses or store values into them.
+
+ Standard C++ allows compound expressions and conditional expressions
+as lvalues, and permits casts to reference type, so use of this
+extension is deprecated for C++ code.
+
+ For example, a compound expression can be assigned, provided the last
+expression in the sequence is an lvalue. These two expressions are
+equivalent:
+
+ (a, b) += 5
+ a, (b += 5)
+
+ Similarly, the address of the compound expression can be taken.
+These two expressions are equivalent:
+
+ &(a, b)
+ a, &b
+
+ A conditional expression is a valid lvalue if its type is not void
+and the true and false branches are both valid lvalues. For example,
+these two expressions are equivalent:
+
+ (a ? b : c) = 5
+ (a ? b = 5 : (c = 5))
+
+ A cast is a valid lvalue if its operand is an lvalue. A simple
+assignment whose left-hand side is a cast works by converting the
+right-hand side first to the specified type, then to the type of the
+inner left-hand side expression. After this is stored, the value is
+converted back to the specified type to become the value of the
+assignment. Thus, if `a' has type `char *', the following two
+expressions are equivalent:
+
+ (int)a = 5
+ (int)(a = (char *)(int)5)
+
+ An assignment-with-arithmetic operation such as `+=' applied to a
+cast performs the arithmetic using the type resulting from the cast,
+and then continues as in the previous case. Therefore, these two
+expressions are equivalent:
+
+ (int)a += 5
+ (int)(a = (char *)(int) ((int)a + 5))
+
+ You cannot take the address of an lvalue cast, because the use of its
+address would not work out coherently. Suppose that `&(int)f' were
+permitted, where `f' has type `float'. Then the following statement
+would try to store an integer bit-pattern where a floating point number
+belongs:
+
+ *&(int)f = 1;
+
+ This is quite different from what `(int)f = 1' would do--that would
+convert 1 to floating point and store it. Rather than cause this
+inconsistency, we think it is better to prohibit use of `&' on a cast.
+
+ If you really do want an `int *' pointer with the address of `f',
+you can simply write `(int *)&f'.
+
+\1f
+File: gcc.info, Node: Conditionals, Next: Long Long, Prev: Lvalues, Up: C Extensions
+
+5.8 Conditionals with Omitted Operands
+======================================
+
+The middle operand in a conditional expression may be omitted. Then if
+the first operand is nonzero, its value is the value of the conditional
+expression.
+
+ Therefore, the expression
+
+ x ? : y
+
+has the value of `x' if that is nonzero; otherwise, the value of `y'.
+
+ This example is perfectly equivalent to
+
+ x ? x : y
+
+In this simple case, the ability to omit the middle operand is not
+especially useful. When it becomes useful is when the first operand
+does, or may (if it is a macro argument), contain a side effect. Then
+repeating the operand in the middle would perform the side effect
+twice. Omitting the middle operand uses the value already computed
+without the undesirable effects of recomputing it.
+
+\1f
+File: gcc.info, Node: Long Long, Next: Complex, Prev: Conditionals, Up: C Extensions
+
+5.9 Double-Word Integers
+========================
+
+ISO C99 supports data types for integers that are at least 64 bits wide,
+and as an extension GCC supports them in C89 mode and in C++. Simply
+write `long long int' for a signed integer, or `unsigned long long int'
+for an unsigned integer. To make an integer constant of type `long
+long int', add the suffix `LL' to the integer. To make an integer
+constant of type `unsigned long long int', add the suffix `ULL' to the
+integer.
+
+ You can use these types in arithmetic like any other integer types.
+Addition, subtraction, and bitwise boolean operations on these types
+are open-coded on all types of machines. Multiplication is open-coded
+if the machine supports fullword-to-doubleword a widening multiply
+instruction. Division and shifts are open-coded only on machines that
+provide special support. The operations that are not open-coded use
+special library routines that come with GCC.
+
+ There may be pitfalls when you use `long long' types for function
+arguments, unless you declare function prototypes. If a function
+expects type `int' for its argument, and you pass a value of type `long
+long int', confusion will result because the caller and the subroutine
+will disagree about the number of bytes for the argument. Likewise, if
+the function expects `long long int' and you pass `int'. The best way
+to avoid such problems is to use prototypes.
+
+\1f
+File: gcc.info, Node: Complex, Next: Hex Floats, Prev: Long Long, Up: C Extensions
+
+5.10 Complex Numbers
+====================
+
+ISO C99 supports complex floating data types, and as an extension GCC
+supports them in C89 mode and in C++, and supports complex integer data
+types which are not part of ISO C99. You can declare complex types
+using the keyword `_Complex'. As an extension, the older GNU keyword
+`__complex__' is also supported.
+
+ For example, `_Complex double x;' declares `x' as a variable whose
+real part and imaginary part are both of type `double'. `_Complex
+short int y;' declares `y' to have real and imaginary parts of type
+`short int'; this is not likely to be useful, but it shows that the set
+of complex types is complete.
+
+ To write a constant with a complex data type, use the suffix `i' or
+`j' (either one; they are equivalent). For example, `2.5fi' has type
+`_Complex float' and `3i' has type `_Complex int'. Such a constant
+always has a pure imaginary value, but you can form any complex value
+you like by adding one to a real constant. This is a GNU extension; if
+you have an ISO C99 conforming C library (such as GNU libc), and want
+to construct complex constants of floating type, you should include
+`<complex.h>' and use the macros `I' or `_Complex_I' instead.
+
+ To extract the real part of a complex-valued expression EXP, write
+`__real__ EXP'. Likewise, use `__imag__' to extract the imaginary
+part. This is a GNU extension; for values of floating type, you should
+use the ISO C99 functions `crealf', `creal', `creall', `cimagf',
+`cimag' and `cimagl', declared in `<complex.h>' and also provided as
+built-in functions by GCC.
+
+ The operator `~' performs complex conjugation when used on a value
+with a complex type. This is a GNU extension; for values of floating
+type, you should use the ISO C99 functions `conjf', `conj' and `conjl',
+declared in `<complex.h>' and also provided as built-in functions by
+GCC.
+
+ GCC can allocate complex automatic variables in a noncontiguous
+fashion; it's even possible for the real part to be in a register while
+the imaginary part is on the stack (or vice-versa). None of the
+supported debugging info formats has a way to represent noncontiguous
+allocation like this, so GCC describes a noncontiguous complex variable
+as if it were two separate variables of noncomplex type. If the
+variable's actual name is `foo', the two fictitious variables are named
+`foo$real' and `foo$imag'. You can examine and set these two
+fictitious variables with your debugger.
+
+ A future version of GDB will know how to recognize such pairs and
+treat them as a single variable with a complex type.
+
+\1f
+File: gcc.info, Node: Hex Floats, Next: Zero Length, Prev: Complex, Up: C Extensions
+
+5.11 Hex Floats
+===============
+
+ISO C99 supports floating-point numbers written not only in the usual
+decimal notation, such as `1.55e1', but also numbers such as `0x1.fp3'
+written in hexadecimal format. As a GNU extension, GCC supports this
+in C89 mode (except in some cases when strictly conforming) and in C++.
+In that format the `0x' hex introducer and the `p' or `P' exponent
+field are mandatory. The exponent is a decimal number that indicates
+the power of 2 by which the significant part will be multiplied. Thus
+`0x1.f' is 1 15/16, `p3' multiplies it by 8, and the value of `0x1.fp3'
+is the same as `1.55e1'.
+
+ Unlike for floating-point numbers in the decimal notation the
+exponent is always required in the hexadecimal notation. Otherwise the
+compiler would not be able to resolve the ambiguity of, e.g., `0x1.f'.
+This could mean `1.0f' or `1.9375' since `f' is also the extension for
+floating-point constants of type `float'.
+
+\1f
+File: gcc.info, Node: Zero Length, Next: Variable Length, Prev: Hex Floats, Up: C Extensions
+
+5.12 Arrays of Length Zero
+==========================
+
+Zero-length arrays are allowed in GNU C. They are very useful as the
+last element of a structure which is really a header for a
+variable-length object:
+
+ struct line {
+ int length;
+ char contents[0];
+ };
+
+ struct line *thisline = (struct line *)
+ malloc (sizeof (struct line) + this_length);
+ thisline->length = this_length;
+
+ In ISO C89, you would have to give `contents' a length of 1, which
+means either you waste space or complicate the argument to `malloc'.
+
+ In ISO C99, you would use a "flexible array member", which is
+slightly different in syntax and semantics:
+
+ * Flexible array members are written as `contents[]' without the `0'.
+
+ * Flexible array members have incomplete type, and so the `sizeof'
+ operator may not be applied. As a quirk of the original
+ implementation of zero-length arrays, `sizeof' evaluates to zero.
+
+ * Flexible array members may only appear as the last member of a
+ `struct' that is otherwise non-empty.
+
+ GCC versions before 3.0 allowed zero-length arrays to be statically
+initialized, as if they were flexible arrays. In addition to those
+cases that were useful, it also allowed initializations in situations
+that would corrupt later data. Non-empty initialization of zero-length
+arrays is now treated like any case where there are more initializer
+elements than the array holds, in that a suitable warning about "excess
+elements in array" is given, and the excess elements (all of them, in
+this case) are ignored.
+
+ Instead GCC allows static initialization of flexible array members.
+This is equivalent to defining a new structure containing the original
+structure followed by an array of sufficient size to contain the data.
+I.e. in the following, `f1' is constructed as if it were declared like
+`f2'.
+
+ struct f1 {
+ int x; int y[];
+ } f1 = { 1, { 2, 3, 4 } };
+
+ struct f2 {
+ struct f1 f1; int data[3];
+ } f2 = { { 1 }, { 2, 3, 4 } };
+
+The convenience of this extension is that `f1' has the desired type,
+eliminating the need to consistently refer to `f2.f1'.
+
+ This has symmetry with normal static arrays, in that an array of
+unknown size is also written with `[]'.
+
+ Of course, this extension only makes sense if the extra data comes at
+the end of a top-level object, as otherwise we would be overwriting
+data at subsequent offsets. To avoid undue complication and confusion
+with initialization of deeply nested arrays, we simply disallow any
+non-empty initialization except when the structure is the top-level
+object. For example:
+
+ struct foo { int x; int y[]; };
+ struct bar { struct foo z; };
+
+ struct foo a = { 1, { 2, 3, 4 } }; // Valid.
+ struct bar b = { { 1, { 2, 3, 4 } } }; // Invalid.
+ struct bar c = { { 1, { } } }; // Valid.
+ struct foo d[1] = { { 1 { 2, 3, 4 } } }; // Invalid.
+
+\1f
+File: gcc.info, Node: Variable Length, Next: Variadic Macros, Prev: Zero Length, Up: C Extensions
+
+5.13 Arrays of Variable Length
+==============================
+
+Variable-length automatic arrays are allowed in ISO C99, and as an
+extension GCC accepts them in C89 mode and in C++. (However, GCC's
+implementation of variable-length arrays does not yet conform in detail
+to the ISO C99 standard.) These arrays are declared like any other
+automatic arrays, but with a length that is not a constant expression.
+The storage is allocated at the point of declaration and deallocated
+when the brace-level is exited. For example:
+
+ FILE *
+ concat_fopen (char *s1, char *s2, char *mode)
+ {
+ char str[strlen (s1) + strlen (s2) + 1];
+ strcpy (str, s1);
+ strcat (str, s2);
+ return fopen (str, mode);
+ }
+
+ Jumping or breaking out of the scope of the array name deallocates
+the storage. Jumping into the scope is not allowed; you get an error
+message for it.
+
+ You can use the function `alloca' to get an effect much like
+variable-length arrays. The function `alloca' is available in many
+other C implementations (but not in all). On the other hand,
+variable-length arrays are more elegant.
+
+ There are other differences between these two methods. Space
+allocated with `alloca' exists until the containing _function_ returns.
+The space for a variable-length array is deallocated as soon as the
+array name's scope ends. (If you use both variable-length arrays and
+`alloca' in the same function, deallocation of a variable-length array
+will also deallocate anything more recently allocated with `alloca'.)
+
+ You can also use variable-length arrays as arguments to functions:
+
+ struct entry
+ tester (int len, char data[len][len])
+ {
+ ...
+ }
+
+ The length of an array is computed once when the storage is allocated
+and is remembered for the scope of the array in case you access it with
+`sizeof'.
+
+ If you want to pass the array first and the length afterward, you can
+use a forward declaration in the parameter list--another GNU extension.
+
+ struct entry
+ tester (int len; char data[len][len], int len)
+ {
+ ...
+ }
+
+ The `int len' before the semicolon is a "parameter forward
+declaration", and it serves the purpose of making the name `len' known
+when the declaration of `data' is parsed.
+
+ You can write any number of such parameter forward declarations in
+the parameter list. They can be separated by commas or semicolons, but
+the last one must end with a semicolon, which is followed by the "real"
+parameter declarations. Each forward declaration must match a "real"
+declaration in parameter name and data type. ISO C99 does not support
+parameter forward declarations.
+
+\1f
+File: gcc.info, Node: Variadic Macros, Next: Escaped Newlines, Prev: Variable Length, Up: C Extensions
+
+5.14 Macros with a Variable Number of Arguments.
+================================================
+
+In the ISO C standard of 1999, a macro can be declared to accept a
+variable number of arguments much as a function can. The syntax for
+defining the macro is similar to that of a function. Here is an
+example:
+
+ #define debug(format, ...) fprintf (stderr, format, __VA_ARGS__)
+
+ Here `...' is a "variable argument". In the invocation of such a
+macro, it represents the zero or more tokens until the closing
+parenthesis that ends the invocation, including any commas. This set of
+tokens replaces the identifier `__VA_ARGS__' in the macro body wherever
+it appears. See the CPP manual for more information.
+
+ GCC has long supported variadic macros, and used a different syntax
+that allowed you to give a name to the variable arguments just like any
+other argument. Here is an example:
+
+ #define debug(format, args...) fprintf (stderr, format, args)
+
+ This is in all ways equivalent to the ISO C example above, but
+arguably more readable and descriptive.
+
+ GNU CPP has two further variadic macro extensions, and permits them
+to be used with either of the above forms of macro definition.
+
+ In standard C, you are not allowed to leave the variable argument out
+entirely; but you are allowed to pass an empty argument. For example,
+this invocation is invalid in ISO C, because there is no comma after
+the string:
+
+ debug ("A message")
+
+ GNU CPP permits you to completely omit the variable arguments in this
+way. In the above examples, the compiler would complain, though since
+the expansion of the macro still has the extra comma after the format
+string.
+
+ To help solve this problem, CPP behaves specially for variable
+arguments used with the token paste operator, `##'. If instead you
+write
+
+ #define debug(format, ...) fprintf (stderr, format, ## __VA_ARGS__)
+
+ and if the variable arguments are omitted or empty, the `##'
+operator causes the preprocessor to remove the comma before it. If you
+do provide some variable arguments in your macro invocation, GNU CPP
+does not complain about the paste operation and instead places the
+variable arguments after the comma. Just like any other pasted macro
+argument, these arguments are not macro expanded.
+
+\1f
+File: gcc.info, Node: Escaped Newlines, Next: Multi-line Strings, Prev: Variadic Macros, Up: C Extensions
+
+5.15 Slightly Looser Rules for Escaped Newlines
+===============================================
+
+Recently, the non-traditional preprocessor has relaxed its treatment of
+escaped newlines. Previously, the newline had to immediately follow a
+backslash. The current implementation allows whitespace in the form of
+spaces, horizontal and vertical tabs, and form feeds between the
+backslash and the subsequent newline. The preprocessor issues a
+warning, but treats it as a valid escaped newline and combines the two
+lines to form a single logical line. This works within comments and
+tokens, including multi-line strings, as well as between tokens.
+Comments are _not_ treated as whitespace for the purposes of this
+relaxation, since they have not yet been replaced with spaces.
+
+\1f
+File: gcc.info, Node: Multi-line Strings, Next: Subscripting, Prev: Escaped Newlines, Up: C Extensions
+
+5.16 String Literals with Embedded Newlines
+===========================================
+
+As an extension, GNU CPP permits string literals to cross multiple lines
+without escaping the embedded newlines. Each embedded newline is
+replaced with a single `\n' character in the resulting string literal,
+regardless of what form the newline took originally.
+
+ CPP currently allows such strings in directives as well (other than
+the `#include' family). This is deprecated and will eventually be
+removed.
+
+\1f
+File: gcc.info, Node: Subscripting, Next: Pointer Arith, Prev: Multi-line Strings, Up: C Extensions
+
+5.17 Non-Lvalue Arrays May Have Subscripts
+==========================================
+
+In ISO C99, arrays that are not lvalues still decay to pointers, and
+may be subscripted, although they may not be modified or used after the
+next sequence point and the unary `&' operator may not be applied to
+them. As an extension, GCC allows such arrays to be subscripted in C89
+mode, though otherwise they do not decay to pointers outside C99 mode.
+For example, this is valid in GNU C though not valid in C89:
+
+ struct foo {int a[4];};
+
+ struct foo f();
+
+ bar (int index)
+ {
+ return f().a[index];
+ }
+
+\1f
+File: gcc.info, Node: Pointer Arith, Next: Initializers, Prev: Subscripting, Up: C Extensions
+
+5.18 Arithmetic on `void'- and Function-Pointers
+================================================
+
+In GNU C, addition and subtraction operations are supported on pointers
+to `void' and on pointers to functions. This is done by treating the
+size of a `void' or of a function as 1.
+
+ A consequence of this is that `sizeof' is also allowed on `void' and
+on function types, and returns 1.
+
+ The option `-Wpointer-arith' requests a warning if these extensions
+are used.
+
+\1f
+File: gcc.info, Node: Initializers, Next: Compound Literals, Prev: Pointer Arith, Up: C Extensions
+
+5.19 Non-Constant Initializers
+==============================
+
+As in standard C++ and ISO C99, the elements of an aggregate
+initializer for an automatic variable are not required to be constant
+expressions in GNU C. Here is an example of an initializer with
+run-time varying elements:
+
+ foo (float f, float g)
+ {
+ float beat_freqs[2] = { f-g, f+g };
+ ...
+ }
+
+\1f
+File: gcc.info, Node: Compound Literals, Next: Designated Inits, Prev: Initializers, Up: C Extensions
+
+5.20 Compound Literals
+======================
+
+ISO C99 supports compound literals. A compound literal looks like a
+cast containing an initializer. Its value is an object of the type
+specified in the cast, containing the elements specified in the
+initializer; it is an lvalue. As an extension, GCC supports compound
+literals in C89 mode and in C++.
+
+ Usually, the specified type is a structure. Assume that `struct
+foo' and `structure' are declared as shown:
+
+ struct foo {int a; char b[2];} structure;
+
+Here is an example of constructing a `struct foo' with a compound
+literal:
+
+ structure = ((struct foo) {x + y, 'a', 0});
+
+This is equivalent to writing the following:
+
+ {
+ struct foo temp = {x + y, 'a', 0};
+ structure = temp;
+ }
+
+ You can also construct an array. If all the elements of the
+compound literal are (made up of) simple constant expressions, suitable
+for use in initializers of objects of static storage duration, then the
+compound literal can be coerced to a pointer to its first element and
+used in such an initializer, as shown here:
+
+ char **foo = (char *[]) { "x", "y", "z" };
+
+ Compound literals for scalar types and union types are is also
+allowed, but then the compound literal is equivalent to a cast.
+
+ As a GNU extension, GCC allows initialization of objects with static
+storage duration by compound literals (which is not possible in ISO
+C99, because the initializer is not a constant). It is handled as if
+the object was initialized only with the bracket enclosed list if
+compound literal's and object types match. The initializer list of the
+compound literal must be constant. If the object being initialized has
+array type of unknown size, the size is determined by compound literal
+size.
+
+ static struct foo x = (struct foo) {1, 'a', 'b'};
+ static int y[] = (int []) {1, 2, 3};
+ static int z[] = (int [3]) {1};
+
+The above lines are equivalent to the following:
+ static struct foo x = {1, 'a', 'b'};
+ static int y[] = {1, 2, 3};
+ static int z[] = {1, 0, 0};
+
+\1f
+File: gcc.info, Node: Designated Inits, Next: Cast to Union, Prev: Compound Literals, Up: C Extensions
+
+5.21 Designated Initializers
+============================
+
+Standard C89 requires the elements of an initializer to appear in a
+fixed order, the same as the order of the elements in the array or
+structure being initialized.
+
+ In ISO C99 you can give the elements in any order, specifying the
+array indices or structure field names they apply to, and GNU C allows
+this as an extension in C89 mode as well. This extension is not
+implemented in GNU C++.
+
+ To specify an array index, write `[INDEX] =' before the element
+value. For example,
+
+ int a[6] = { [4] = 29, [2] = 15 };
+
+is equivalent to
+
+ int a[6] = { 0, 0, 15, 0, 29, 0 };
+
+The index values must be constant expressions, even if the array being
+initialized is automatic.
+
+ An alternative syntax for this which has been obsolete since GCC 2.5
+but GCC still accepts is to write `[INDEX]' before the element value,
+with no `='.
+
+ To initialize a range of elements to the same value, write `[FIRST
+... LAST] = VALUE'. This is a GNU extension. For example,
+
+ int widths[] = { [0 ... 9] = 1, [10 ... 99] = 2, [100] = 3 };
+
+If the value in it has side-effects, the side-effects will happen only
+once, not for each initialized field by the range initializer.
+
+Note that the length of the array is the highest value specified plus
+one.
+
+ In a structure initializer, specify the name of a field to initialize
+with `.FIELDNAME =' before the element value. For example, given the
+following structure,
+
+ struct point { int x, y; };
+
+the following initialization
+
+ struct point p = { .y = yvalue, .x = xvalue };
+
+is equivalent to
+
+ struct point p = { xvalue, yvalue };
+
+ Another syntax which has the same meaning, obsolete since GCC 2.5, is
+`FIELDNAME:', as shown here:
+
+ struct point p = { y: yvalue, x: xvalue };
+
+ The `[INDEX]' or `.FIELDNAME' is known as a "designator". You can
+also use a designator (or the obsolete colon syntax) when initializing
+a union, to specify which element of the union should be used. For
+example,
+
+ union foo { int i; double d; };
+
+ union foo f = { .d = 4 };
+
+will convert 4 to a `double' to store it in the union using the second
+element. By contrast, casting 4 to type `union foo' would store it
+into the union as the integer `i', since it is an integer. (*Note Cast
+to Union::.)
+
+ You can combine this technique of naming elements with ordinary C
+initialization of successive elements. Each initializer element that
+does not have a designator applies to the next consecutive element of
+the array or structure. For example,
+
+ int a[6] = { [1] = v1, v2, [4] = v4 };
+
+is equivalent to
+
+ int a[6] = { 0, v1, v2, 0, v4, 0 };
+
+ Labeling the elements of an array initializer is especially useful
+when the indices are characters or belong to an `enum' type. For
+example:
+
+ int whitespace[256]
+ = { [' '] = 1, ['\t'] = 1, ['\h'] = 1,
+ ['\f'] = 1, ['\n'] = 1, ['\r'] = 1 };
+
+ You can also write a series of `.FIELDNAME' and `[INDEX]'
+designators before an `=' to specify a nested subobject to initialize;
+the list is taken relative to the subobject corresponding to the
+closest surrounding brace pair. For example, with the `struct point'
+declaration above:
+
+ struct point ptarray[10] = { [2].y = yv2, [2].x = xv2, [0].x = xv0 };
+
+If the same field is initialized multiple times, it will have value from
+the last initialization. If any such overridden initialization has
+side-effect, it is unspecified whether the side-effect happens or not.
+Currently, gcc will discard them and issue a warning.
+
+\1f
+File: gcc.info, Node: Case Ranges, Next: Mixed Declarations, Prev: Cast to Union, Up: C Extensions
+
+5.22 Case Ranges
+================
+
+You can specify a range of consecutive values in a single `case' label,
+like this:
+
+ case LOW ... HIGH:
+
+This has the same effect as the proper number of individual `case'
+labels, one for each integer value from LOW to HIGH, inclusive.
+
+ This feature is especially useful for ranges of ASCII character
+codes:
+
+ case 'A' ... 'Z':
+
+ *Be careful:* Write spaces around the `...', for otherwise it may be
+parsed wrong when you use it with integer values. For example, write
+this:
+
+ case 1 ... 5:
+
+rather than this:
+
+ case 1...5:
+
+\1f
+File: gcc.info, Node: Cast to Union, Next: Case Ranges, Prev: Designated Inits, Up: C Extensions
+
+5.23 Cast to a Union Type
+=========================
+
+A cast to union type is similar to other casts, except that the type
+specified is a union type. You can specify the type either with `union
+TAG' or with a typedef name. A cast to union is actually a constructor
+though, not a cast, and hence does not yield an lvalue like normal
+casts. (*Note Compound Literals::.)
+
+ The types that may be cast to the union type are those of the members
+of the union. Thus, given the following union and variables:
+
+ union foo { int i; double d; };
+ int x;
+ double y;
+
+both `x' and `y' can be cast to type `union foo'.
+
+ Using the cast as the right-hand side of an assignment to a variable
+of union type is equivalent to storing in a member of the union:
+
+ union foo u;
+ ...
+ u = (union foo) x == u.i = x
+ u = (union foo) y == u.d = y
+
+ You can also use the union cast as a function argument:
+
+ void hack (union foo);
+ ...
+ hack ((union foo) x);
+
+\1f
+File: gcc.info, Node: Mixed Declarations, Next: Function Attributes, Prev: Case Ranges, Up: C Extensions
+
+5.24 Mixed Declarations and Code
+================================
+
+ISO C99 and ISO C++ allow declarations and code to be freely mixed
+within compound statements. As an extension, GCC also allows this in
+C89 mode. For example, you could do:
+
+ int i;
+ ...
+ i++;
+ int j = i + 2;
+
+ Each identifier is visible from where it is declared until the end of
+the enclosing block.
+
+\1f
+File: gcc.info, Node: Function Attributes, Next: Attribute Syntax, Prev: Mixed Declarations, Up: C Extensions
+
+5.25 Declaring Attributes of Functions
+======================================
+
+In GNU C, you declare certain things about functions called in your
+program which help the compiler optimize function calls and check your
+code more carefully.
+
+ The keyword `__attribute__' allows you to specify special attributes
+when making a declaration. This keyword is followed by an attribute
+specification inside double parentheses. The following attributes are
+currently defined for functions on all targets: `noreturn', `noinline',
+`always_inline', `pure', `const', `format', `format_arg',
+`no_instrument_function', `section', `constructor', `destructor',
+`used', `unused', `deprecated', `weak', `malloc', and `alias'. Several
+other attributes are defined for functions on particular target
+systems. Other attributes, including `section' are supported for
+variables declarations (*note Variable Attributes::) and for types
+(*note Type Attributes::).
+
+ You may also specify attributes with `__' preceding and following
+each keyword. This allows you to use them in header files without
+being concerned about a possible macro of the same name. For example,
+you may use `__noreturn__' instead of `noreturn'.
+
+ *Note Attribute Syntax::, for details of the exact syntax for using
+attributes.
+
+`noreturn'
+ A few standard library functions, such as `abort' and `exit',
+ cannot return. GCC knows this automatically. Some programs define
+ their own functions that never return. You can declare them
+ `noreturn' to tell the compiler this fact. For example,
+
+ void fatal () __attribute__ ((noreturn));
+
+ void
+ fatal (...)
+ {
+ ... /* Print error message. */ ...
+ exit (1);
+ }
+
+ The `noreturn' keyword tells the compiler to assume that `fatal'
+ cannot return. It can then optimize without regard to what would
+ happen if `fatal' ever did return. This makes slightly better
+ code. More importantly, it helps avoid spurious warnings of
+ uninitialized variables.
+
+ Do not assume that registers saved by the calling function are
+ restored before calling the `noreturn' function.
+
+ It does not make sense for a `noreturn' function to have a return
+ type other than `void'.
+
+ The attribute `noreturn' is not implemented in GCC versions
+ earlier than 2.5. An alternative way to declare that a function
+ does not return, which works in the current version and in some
+ older versions, is as follows:
+
+ typedef void voidfn ();
+
+ volatile voidfn fatal;
+
+`noinline'
+ This function attribute prevents a function from being considered
+ for inlining.
+
+`always_inline'
+ Generally, functions are not inlined unless optimization is
+ specified. For functions declared inline, this attribute inlines
+ the function even if no optimization level was specified.
+
+`pure'
+ Many functions have no effects except the return value and their
+ return value depends only on the parameters and/or global
+ variables. Such a function can be subject to common subexpression
+ elimination and loop optimization just as an arithmetic operator
+ would be. These functions should be declared with the attribute
+ `pure'. For example,
+
+ int square (int) __attribute__ ((pure));
+
+ says that the hypothetical function `square' is safe to call fewer
+ times than the program says.
+
+ Some of common examples of pure functions are `strlen' or `memcmp'.
+ Interesting non-pure functions are functions with infinite loops
+ or those depending on volatile memory or other system resource,
+ that may change between two consecutive calls (such as `feof' in a
+ multithreading environment).
+
+ The attribute `pure' is not implemented in GCC versions earlier
+ than 2.96.
+
+`const'
+ Many functions do not examine any values except their arguments,
+ and have no effects except the return value. Basically this is
+ just slightly more strict class than the `pure' attribute above,
+ since function is not allowed to read global memory.
+
+ Note that a function that has pointer arguments and examines the
+ data pointed to must _not_ be declared `const'. Likewise, a
+ function that calls a non-`const' function usually must not be
+ `const'. It does not make sense for a `const' function to return
+ `void'.
+
+ The attribute `const' is not implemented in GCC versions earlier
+ than 2.5. An alternative way to declare that a function has no
+ side effects, which works in the current version and in some older
+ versions, is as follows:
+
+ typedef int intfn ();
+
+ extern const intfn square;
+
+ This approach does not work in GNU C++ from 2.6.0 on, since the
+ language specifies that the `const' must be attached to the return
+ value.
+
+`format (ARCHETYPE, STRING-INDEX, FIRST-TO-CHECK)'
+ The `format' attribute specifies that a function takes `printf',
+ `scanf', `strftime' or `strfmon' style arguments which should be
+ type-checked against a format string. For example, the
+ declaration:
+
+ extern int
+ my_printf (void *my_object, const char *my_format, ...)
+ __attribute__ ((format (printf, 2, 3)));
+
+ causes the compiler to check the arguments in calls to `my_printf'
+ for consistency with the `printf' style format string argument
+ `my_format'.
+
+ The parameter ARCHETYPE determines how the format string is
+ interpreted, and should be `printf', `scanf', `strftime' or
+ `strfmon'. (You can also use `__printf__', `__scanf__',
+ `__strftime__' or `__strfmon__'.) The parameter STRING-INDEX
+ specifies which argument is the format string argument (starting
+ from 1), while FIRST-TO-CHECK is the number of the first argument
+ to check against the format string. For functions where the
+ arguments are not available to be checked (such as `vprintf'),
+ specify the third parameter as zero. In this case the compiler
+ only checks the format string for consistency. For `strftime'
+ formats, the third parameter is required to be zero.
+
+ In the example above, the format string (`my_format') is the second
+ argument of the function `my_print', and the arguments to check
+ start with the third argument, so the correct parameters for the
+ format attribute are 2 and 3.
+
+ The `format' attribute allows you to identify your own functions
+ which take format strings as arguments, so that GCC can check the
+ calls to these functions for errors. The compiler always (unless
+ `-ffreestanding' is used) checks formats for the standard library
+ functions `printf', `fprintf', `sprintf', `scanf', `fscanf',
+ `sscanf', `strftime', `vprintf', `vfprintf' and `vsprintf'
+ whenever such warnings are requested (using `-Wformat'), so there
+ is no need to modify the header file `stdio.h'. In C99 mode, the
+ functions `snprintf', `vsnprintf', `vscanf', `vfscanf' and
+ `vsscanf' are also checked. Except in strictly conforming C
+ standard modes, the X/Open function `strfmon' is also checked as
+ are `printf_unlocked' and `fprintf_unlocked'. *Note Options
+ Controlling C Dialect: C Dialect Options.
+
+`format_arg (STRING-INDEX)'
+ The `format_arg' attribute specifies that a function takes a format
+ string for a `printf', `scanf', `strftime' or `strfmon' style
+ function and modifies it (for example, to translate it into
+ another language), so the result can be passed to a `printf',
+ `scanf', `strftime' or `strfmon' style function (with the
+ remaining arguments to the format function the same as they would
+ have been for the unmodified string). For example, the
+ declaration:
+
+ extern char *
+ my_dgettext (char *my_domain, const char *my_format)
+ __attribute__ ((format_arg (2)));
+
+ causes the compiler to check the arguments in calls to a `printf',
+ `scanf', `strftime' or `strfmon' type function, whose format
+ string argument is a call to the `my_dgettext' function, for
+ consistency with the format string argument `my_format'. If the
+ `format_arg' attribute had not been specified, all the compiler
+ could tell in such calls to format functions would be that the
+ format string argument is not constant; this would generate a
+ warning when `-Wformat-nonliteral' is used, but the calls could
+ not be checked without the attribute.
+
+ The parameter STRING-INDEX specifies which argument is the format
+ string argument (starting from 1).
+
+ The `format-arg' attribute allows you to identify your own
+ functions which modify format strings, so that GCC can check the
+ calls to `printf', `scanf', `strftime' or `strfmon' type function
+ whose operands are a call to one of your own function. The
+ compiler always treats `gettext', `dgettext', and `dcgettext' in
+ this manner except when strict ISO C support is requested by
+ `-ansi' or an appropriate `-std' option, or `-ffreestanding' is
+ used. *Note Options Controlling C Dialect: C Dialect Options.
+
+`no_instrument_function'
+ If `-finstrument-functions' is given, profiling function calls will
+ be generated at entry and exit of most user-compiled functions.
+ Functions with this attribute will not be so instrumented.
+
+`section ("SECTION-NAME")'
+ Normally, the compiler places the code it generates in the `text'
+ section. Sometimes, however, you need additional sections, or you
+ need certain particular functions to appear in special sections.
+ The `section' attribute specifies that a function lives in a
+ particular section. For example, the declaration:
+
+ extern void foobar (void) __attribute__ ((section ("bar")));
+
+ puts the function `foobar' in the `bar' section.
+
+ Some file formats do not support arbitrary sections so the
+ `section' attribute is not available on all platforms. If you
+ need to map the entire contents of a module to a particular
+ section, consider using the facilities of the linker instead.
+
+`constructor'
+`destructor'
+ The `constructor' attribute causes the function to be called
+ automatically before execution enters `main ()'. Similarly, the
+ `destructor' attribute causes the function to be called
+ automatically after `main ()' has completed or `exit ()' has been
+ called. Functions with these attributes are useful for
+ initializing data that will be used implicitly during the
+ execution of the program.
+
+ These attributes are not currently implemented for Objective-C.
+
+`unused'
+ This attribute, attached to a function, means that the function is
+ meant to be possibly unused. GCC will not produce a warning for
+ this function. GNU C++ does not currently support this attribute
+ as definitions without parameters are valid in C++.
+
+`used'
+ This attribute, attached to a function, means that code must be
+ emitted for the function even if it appears that the function is
+ not referenced. This is useful, for example, when the function is
+ referenced only in inline assembly.
+
+`deprecated'
+ The `deprecated' attribute results in a warning if the function is
+ used anywhere in the source file. This is useful when identifying
+ functions that are expected to be removed in a future version of a
+ program. The warning also includes the location of the declaration
+ of the deprecated function, to enable users to easily find further
+ information about why the function is deprecated, or what they
+ should do instead. Note that the warnings only occurs for uses:
+
+ int old_fn () __attribute__ ((deprecated));
+ int old_fn ();
+ int (*fn_ptr)() = old_fn;
+
+ results in a warning on line 3 but not line 2.
+
+ The `deprecated' attribute can also be used for variables and
+ types (*note Variable Attributes::, *note Type Attributes::.)
+
+`weak'
+ The `weak' attribute causes the declaration to be emitted as a weak
+ symbol rather than a global. This is primarily useful in defining
+ library functions which can be overridden in user code, though it
+ can also be used with non-function declarations. Weak symbols are
+ supported for ELF targets, and also for a.out targets when using
+ the GNU assembler and linker.
+
+`malloc'
+ The `malloc' attribute is used to tell the compiler that a function
+ may be treated as if it were the malloc function. The compiler
+ assumes that calls to malloc result in a pointers that cannot
+ alias anything. This will often improve optimization.
+
+`alias ("TARGET")'
+ The `alias' attribute causes the declaration to be emitted as an
+ alias for another symbol, which must be specified. For instance,
+
+ void __f () { /* do something */; }
+ void f () __attribute__ ((weak, alias ("__f")));
+
+ declares `f' to be a weak alias for `__f'. In C++, the mangled
+ name for the target must be used.
+
+ Not all target machines support this attribute.
+
+`regparm (NUMBER)'
+ On the Intel 386, the `regparm' attribute causes the compiler to
+ pass up to NUMBER integer arguments in registers EAX, EDX, and ECX
+ instead of on the stack. Functions that take a variable number of
+ arguments will continue to be passed all of their arguments on the
+ stack.
+
+`stdcall'
+ On the Intel 386, the `stdcall' attribute causes the compiler to
+ assume that the called function will pop off the stack space used
+ to pass arguments, unless it takes a variable number of arguments.
+
+ The PowerPC compiler for Windows NT currently ignores the `stdcall'
+ attribute.
+
+`cdecl'
+ On the Intel 386, the `cdecl' attribute causes the compiler to
+ assume that the calling function will pop off the stack space used
+ to pass arguments. This is useful to override the effects of the
+ `-mrtd' switch.
+
+ The PowerPC compiler for Windows NT currently ignores the `cdecl'
+ attribute.
+
+`longcall'
+ On the RS/6000 and PowerPC, the `longcall' attribute causes the
+ compiler to always call the function via a pointer, so that
+ functions which reside further than 64 megabytes (67,108,864
+ bytes) from the current location can be called.
+
+`long_call/short_call'
+ This attribute allows to specify how to call a particular function
+ on ARM. Both attributes override the `-mlong-calls' (*note ARM
+ Options::) command line switch and `#pragma long_calls' settings.
+ The `long_call' attribute causes the compiler to always call the
+ function by first loading its address into a register and then
+ using the contents of that register. The `short_call' attribute
+ always places the offset to the function from the call site into
+ the `BL' instruction directly.
+
+`dllimport'
+ On the PowerPC running Windows NT, the `dllimport' attribute causes
+ the compiler to call the function via a global pointer to the
+ function pointer that is set up by the Windows NT dll library.
+ The pointer name is formed by combining `__imp_' and the function
+ name.
+
+`dllexport'
+ On the PowerPC running Windows NT, the `dllexport' attribute causes
+ the compiler to provide a global pointer to the function pointer,
+ so that it can be called with the `dllimport' attribute. The
+ pointer name is formed by combining `__imp_' and the function name.
+
+`exception (EXCEPT-FUNC [, EXCEPT-ARG])'
+ On the PowerPC running Windows NT, the `exception' attribute causes
+ the compiler to modify the structured exception table entry it
+ emits for the declared function. The string or identifier
+ EXCEPT-FUNC is placed in the third entry of the structured
+ exception table. It represents a function, which is called by the
+ exception handling mechanism if an exception occurs. If it was
+ specified, the string or identifier EXCEPT-ARG is placed in the
+ fourth entry of the structured exception table.
+
+`function_vector'
+ Use this attribute on the H8/300 and H8/300H to indicate that the
+ specified function should be called through the function vector.
+ Calling a function through the function vector will reduce code
+ size, however; the function vector has a limited size (maximum 128
+ entries on the H8/300 and 64 entries on the H8/300H) and shares
+ space with the interrupt vector.
+
+ You must use GAS and GLD from GNU binutils version 2.7 or later for
+ this attribute to work correctly.
+
+`interrupt'
+ Use this attribute on the ARM, AVR, M32R/D and Xstormy16 ports to
+ indicate that the specified function is an interrupt handler. The
+ compiler will generate function entry and exit sequences suitable
+ for use in an interrupt handler when this attribute is present.
+
+ Note, interrupt handlers for the H8/300, H8/300H and SH processors
+ can be specified via the `interrupt_handler' attribute.
+
+ Note, on the AVR interrupts will be enabled inside the function.
+
+ Note, for the ARM you can specify the kind of interrupt to be
+ handled by adding an optional parameter to the interrupt attribute
+ like this:
+
+ void f () __attribute__ ((interrupt ("IRQ")));
+
+ Permissible values for this parameter are: IRQ, FIQ, SWI, ABORT
+ and UNDEF.
+
+`interrupt_handler'
+ Use this attribute on the H8/300, H8/300H and SH to indicate that
+ the specified function is an interrupt handler. The compiler will
+ generate function entry and exit sequences suitable for use in an
+ interrupt handler when this attribute is present.
+
+`sp_switch'
+ Use this attribute on the SH to indicate an `interrupt_handler'
+ function should switch to an alternate stack. It expects a string
+ argument that names a global variable holding the address of the
+ alternate stack.
+
+ void *alt_stack;
+ void f () __attribute__ ((interrupt_handler,
+ sp_switch ("alt_stack")));
+
+`trap_exit'
+ Use this attribute on the SH for an `interrupt_handle' to return
+ using `trapa' instead of `rte'. This attribute expects an integer
+ argument specifying the trap number to be used.
+
+`eightbit_data'
+ Use this attribute on the H8/300 and H8/300H to indicate that the
+ specified variable should be placed into the eight bit data
+ section. The compiler will generate more efficient code for
+ certain operations on data in the eight bit data area. Note the
+ eight bit data area is limited to 256 bytes of data.
+
+ You must use GAS and GLD from GNU binutils version 2.7 or later for
+ this attribute to work correctly.
+
+`tiny_data'
+ Use this attribute on the H8/300H to indicate that the specified
+ variable should be placed into the tiny data section. The
+ compiler will generate more efficient code for loads and stores on
+ data in the tiny data section. Note the tiny data area is limited
+ to slightly under 32kbytes of data.
+
+`signal'
+ Use this attribute on the AVR to indicate that the specified
+ function is an signal handler. The compiler will generate function
+ entry and exit sequences suitable for use in an signal handler
+ when this attribute is present. Interrupts will be disabled
+ inside function.
+
+`naked'
+ Use this attribute on the ARM or AVR ports to indicate that the
+ specified function do not need prologue/epilogue sequences
+ generated by the compiler. It is up to the programmer to provide
+ these sequences.
+
+`model (MODEL-NAME)'
+ Use this attribute on the M32R/D to set the addressability of an
+ object, and the code generated for a function. The identifier
+ MODEL-NAME is one of `small', `medium', or `large', representing
+ each of the code models.
+
+ Small model objects live in the lower 16MB of memory (so that their
+ addresses can be loaded with the `ld24' instruction), and are
+ callable with the `bl' instruction.
+
+ Medium model objects may live anywhere in the 32-bit address space
+ (the compiler will generate `seth/add3' instructions to load their
+ addresses), and are callable with the `bl' instruction.
+
+ Large model objects may live anywhere in the 32-bit address space
+ (the compiler will generate `seth/add3' instructions to load their
+ addresses), and may not be reachable with the `bl' instruction
+ (the compiler will generate the much slower `seth/add3/jl'
+ instruction sequence).
+
+
+ You can specify multiple attributes in a declaration by separating
+them by commas within the double parentheses or by immediately
+following an attribute declaration with another attribute declaration.
+
+ Some people object to the `__attribute__' feature, suggesting that
+ISO C's `#pragma' should be used instead. At the time `__attribute__'
+was designed, there were two reasons for not doing this.
+
+ 1. It is impossible to generate `#pragma' commands from a macro.
+
+ 2. There is no telling what the same `#pragma' might mean in another
+ compiler.
+
+ These two reasons applied to almost any application that might have
+been proposed for `#pragma'. It was basically a mistake to use
+`#pragma' for _anything_.
+
+ The ISO C99 standard includes `_Pragma', which now allows pragmas to
+be generated from macros. In addition, a `#pragma GCC' namespace is
+now in use for GCC-specific pragmas. However, it has been found
+convenient to use `__attribute__' to achieve a natural attachment of
+attributes to their corresponding declarations, whereas `#pragma GCC'
+is of use for constructs that do not naturally form part of the
+grammar. *Note Miscellaneous Preprocessing Directives: (cpp)Other
+Directives.
+
+\1f
+File: gcc.info, Node: Attribute Syntax, Next: Function Prototypes, Prev: Function Attributes, Up: C Extensions
+
+5.26 Attribute Syntax
+=====================
+
+This section describes the syntax with which `__attribute__' may be
+used, and the constructs to which attribute specifiers bind, for the C
+language. Some details may vary for C++ and Objective-C. Because of
+infelicities in the grammar for attributes, some forms described here
+may not be successfully parsed in all cases.
+
+ There are some problems with the semantics of attributes in C++. For
+example, there are no manglings for attributes, although they may affect
+code generation, so problems may arise when attributed types are used in
+conjunction with templates or overloading. Similarly, `typeid' does
+not distinguish between types with different attributes. Support for
+attributes in C++ may be restricted in future to attributes on
+declarations only, but not on nested declarators.
+
+ *Note Function Attributes::, for details of the semantics of
+attributes applying to functions. *Note Variable Attributes::, for
+details of the semantics of attributes applying to variables. *Note
+Type Attributes::, for details of the semantics of attributes applying
+to structure, union and enumerated types.
+
+ An "attribute specifier" is of the form `__attribute__
+((ATTRIBUTE-LIST))'. An "attribute list" is a possibly empty
+comma-separated sequence of "attributes", where each attribute is one
+of the following:
+
+ * Empty. Empty attributes are ignored.
+
+ * A word (which may be an identifier such as `unused', or a reserved
+ word such as `const').
+
+ * A word, followed by, in parentheses, parameters for the attribute.
+ These parameters take one of the following forms:
+
+ * An identifier. For example, `mode' attributes use this form.
+
+ * An identifier followed by a comma and a non-empty
+ comma-separated list of expressions. For example, `format'
+ attributes use this form.
+
+ * A possibly empty comma-separated list of expressions. For
+ example, `format_arg' attributes use this form with the list
+ being a single integer constant expression, and `alias'
+ attributes use this form with the list being a single string
+ constant.
+
+ An "attribute specifier list" is a sequence of one or more attribute
+specifiers, not separated by any other tokens.
+
+ An attribute specifier list may appear after the colon following a
+label, other than a `case' or `default' label. The only attribute it
+makes sense to use after a label is `unused'. This feature is intended
+for code generated by programs which contains labels that may be unused
+but which is compiled with `-Wall'. It would not normally be
+appropriate to use in it human-written code, though it could be useful
+in cases where the code that jumps to the label is contained within an
+`#ifdef' conditional.
+
+ An attribute specifier list may appear as part of a `struct',
+`union' or `enum' specifier. It may go either immediately after the
+`struct', `union' or `enum' keyword, or after the closing brace. It is
+ignored if the content of the structure, union or enumerated type is
+not defined in the specifier in which the attribute specifier list is
+used--that is, in usages such as `struct __attribute__((foo)) bar' with
+no following opening brace. Where attribute specifiers follow the
+closing brace, they are considered to relate to the structure, union or
+enumerated type defined, not to any enclosing declaration the type
+specifier appears in, and the type defined is not complete until after
+the attribute specifiers.
+
+ Otherwise, an attribute specifier appears as part of a declaration,
+counting declarations of unnamed parameters and type names, and relates
+to that declaration (which may be nested in another declaration, for
+example in the case of a parameter declaration), or to a particular
+declarator within a declaration. Where an attribute specifier is
+applied to a parameter declared as a function or an array, it should
+apply to the function or array rather than the pointer to which the
+parameter is implicitly converted, but this is not yet correctly
+implemented.
+
+ Any list of specifiers and qualifiers at the start of a declaration
+may contain attribute specifiers, whether or not such a list may in that
+context contain storage class specifiers. (Some attributes, however,
+are essentially in the nature of storage class specifiers, and only make
+sense where storage class specifiers may be used; for example,
+`section'.) There is one necessary limitation to this syntax: the
+first old-style parameter declaration in a function definition cannot
+begin with an attribute specifier, because such an attribute applies to
+the function instead by syntax described below (which, however, is not
+yet implemented in this case). In some other cases, attribute
+specifiers are permitted by this grammar but not yet supported by the
+compiler. All attribute specifiers in this place relate to the
+declaration as a whole. In the obsolescent usage where a type of `int'
+is implied by the absence of type specifiers, such a list of specifiers
+and qualifiers may be an attribute specifier list with no other
+specifiers or qualifiers.
+
+ An attribute specifier list may appear immediately before a
+declarator (other than the first) in a comma-separated list of
+declarators in a declaration of more than one identifier using a single
+list of specifiers and qualifiers. Such attribute specifiers apply
+only to the identifier before whose declarator they appear. For
+example, in
+
+ __attribute__((noreturn)) void d0 (void),
+ __attribute__((format(printf, 1, 2))) d1 (const char *, ...),
+ d2 (void)
+
+the `noreturn' attribute applies to all the functions declared; the
+`format' attribute only applies to `d1'.
+
+ An attribute specifier list may appear immediately before the comma,
+`=' or semicolon terminating the declaration of an identifier other
+than a function definition. At present, such attribute specifiers apply
+to the declared object or function, but in future they may attach to the
+outermost adjacent declarator. In simple cases there is no difference,
+but, for example, in
+
+ void (****f)(void) __attribute__((noreturn));
+
+at present the `noreturn' attribute applies to `f', which causes a
+warning since `f' is not a function, but in future it may apply to the
+function `****f'. The precise semantics of what attributes in such
+cases will apply to are not yet specified. Where an assembler name for
+an object or function is specified (*note Asm Labels::), at present the
+attribute must follow the `asm' specification; in future, attributes
+before the `asm' specification may apply to the adjacent declarator,
+and those after it to the declared object or function.
+
+ An attribute specifier list may, in future, be permitted to appear
+after the declarator in a function definition (before any old-style
+parameter declarations or the function body).
+
+ Attribute specifiers may be mixed with type qualifiers appearing
+inside the `[]' of a parameter array declarator, in the C99 construct by
+which such qualifiers are applied to the pointer to which the array is
+implicitly converted. Such attribute specifiers apply to the pointer,
+not to the array, but at present this is not implemented and they are
+ignored.
+
+ An attribute specifier list may appear at the start of a nested
+declarator. At present, there are some limitations in this usage: the
+attributes correctly apply to the declarator, but for most individual
+attributes the semantics this implies are not implemented. When
+attribute specifiers follow the `*' of a pointer declarator, they may
+be mixed with any type qualifiers present. The following describes the
+formal semantics of this syntax. It will make the most sense if you
+are familiar with the formal specification of declarators in the ISO C
+standard.
+
+ Consider (as in C99 subclause 6.7.5 paragraph 4) a declaration `T
+D1', where `T' contains declaration specifiers that specify a type TYPE
+(such as `int') and `D1' is a declarator that contains an identifier
+IDENT. The type specified for IDENT for derived declarators whose type
+does not include an attribute specifier is as in the ISO C standard.
+
+ If `D1' has the form `( ATTRIBUTE-SPECIFIER-LIST D )', and the
+declaration `T D' specifies the type "DERIVED-DECLARATOR-TYPE-LIST
+TYPE" for IDENT, then `T D1' specifies the type
+"DERIVED-DECLARATOR-TYPE-LIST ATTRIBUTE-SPECIFIER-LIST TYPE" for IDENT.
+
+ If `D1' has the form `* TYPE-QUALIFIER-AND-ATTRIBUTE-SPECIFIER-LIST
+D', and the declaration `T D' specifies the type
+"DERIVED-DECLARATOR-TYPE-LIST TYPE" for IDENT, then `T D1' specifies
+the type "DERIVED-DECLARATOR-TYPE-LIST
+TYPE-QUALIFIER-AND-ATTRIBUTE-SPECIFIER-LIST TYPE" for IDENT.
+
+ For example,
+
+ void (__attribute__((noreturn)) ****f) (void);
+
+specifies the type "pointer to pointer to pointer to pointer to
+non-returning function returning `void'". As another example,
+
+ char *__attribute__((aligned(8))) *f;
+
+specifies the type "pointer to 8-byte-aligned pointer to `char'". Note
+again that this does not work with most attributes; for example, the
+usage of `aligned' and `noreturn' attributes given above is not yet
+supported.
+
+ For compatibility with existing code written for compiler versions
+that did not implement attributes on nested declarators, some laxity is
+allowed in the placing of attributes. If an attribute that only applies
+to types is applied to a declaration, it will be treated as applying to
+the type of that declaration. If an attribute that only applies to
+declarations is applied to the type of a declaration, it will be treated
+as applying to that declaration; and, for compatibility with code
+placing the attributes immediately before the identifier declared, such
+an attribute applied to a function return type will be treated as
+applying to the function type, and such an attribute applied to an array
+element type will be treated as applying to the array type. If an
+attribute that only applies to function types is applied to a
+pointer-to-function type, it will be treated as applying to the pointer
+target type; if such an attribute is applied to a function return type
+that is not a pointer-to-function type, it will be treated as applying
+to the function type.
+
+\1f
+File: gcc.info, Node: Function Prototypes, Next: C++ Comments, Prev: Attribute Syntax, Up: C Extensions
+
+5.27 Prototypes and Old-Style Function Definitions
+==================================================
+
+GNU C extends ISO C to allow a function prototype to override a later
+old-style non-prototype definition. Consider the following example:
+
+ /* Use prototypes unless the compiler is old-fashioned. */
+ #ifdef __STDC__
+ #define P(x) x
+ #else
+ #define P(x) ()
+ #endif
+
+ /* Prototype function declaration. */
+ int isroot P((uid_t));
+
+ /* Old-style function definition. */
+ int
+ isroot (x) /* ??? lossage here ??? */
+ uid_t x;
+ {
+ return x == 0;
+ }
+
+ Suppose the type `uid_t' happens to be `short'. ISO C does not
+allow this example, because subword arguments in old-style
+non-prototype definitions are promoted. Therefore in this example the
+function definition's argument is really an `int', which does not match
+the prototype argument type of `short'.
+
+ This restriction of ISO C makes it hard to write code that is
+portable to traditional C compilers, because the programmer does not
+know whether the `uid_t' type is `short', `int', or `long'. Therefore,
+in cases like these GNU C allows a prototype to override a later
+old-style definition. More precisely, in GNU C, a function prototype
+argument type overrides the argument type specified by a later
+old-style definition if the former type is the same as the latter type
+before promotion. Thus in GNU C the above example is equivalent to the
+following:
+
+ int isroot (uid_t);
+
+ int
+ isroot (uid_t x)
+ {
+ return x == 0;
+ }
+
+GNU C++ does not support old-style function definitions, so this
+extension is irrelevant.
+
+\1f
+File: gcc.info, Node: C++ Comments, Next: Dollar Signs, Prev: Function Prototypes, Up: C Extensions
+
+5.28 C++ Style Comments
+=======================
+
+In GNU C, you may use C++ style comments, which start with `//' and
+continue until the end of the line. Many other C implementations allow
+such comments, and they are likely to be in a future C standard.
+However, C++ style comments are not recognized if you specify `-ansi',
+a `-std' option specifying a version of ISO C before C99, or
+`-traditional', since they are incompatible with traditional constructs
+like `dividend//*comment*/divisor'.
+
+\1f
+File: gcc.info, Node: Dollar Signs, Next: Character Escapes, Prev: C++ Comments, Up: C Extensions
+
+5.29 Dollar Signs in Identifier Names
+=====================================
+
+In GNU C, you may normally use dollar signs in identifier names. This
+is because many traditional C implementations allow such identifiers.
+However, dollar signs in identifiers are not supported on a few target
+machines, typically because the target assembler does not allow them.
+
+\1f
+File: gcc.info, Node: Character Escapes, Next: Variable Attributes, Prev: Dollar Signs, Up: C Extensions
+
+5.30 The Character <ESC> in Constants
+=====================================
+
+You can use the sequence `\e' in a string or character constant to
+stand for the ASCII character <ESC>.
+
+\1f
+File: gcc.info, Node: Alignment, Next: Inline, Prev: Type Attributes, Up: C Extensions
+
+5.31 Inquiring on Alignment of Types or Variables
+=================================================
+
+The keyword `__alignof__' allows you to inquire about how an object is
+aligned, or the minimum alignment usually required by a type. Its
+syntax is just like `sizeof'.
+
+ For example, if the target machine requires a `double' value to be
+aligned on an 8-byte boundary, then `__alignof__ (double)' is 8. This
+is true on many RISC machines. On more traditional machine designs,
+`__alignof__ (double)' is 4 or even 2.
+
+ Some machines never actually require alignment; they allow reference
+to any data type even at an odd addresses. For these machines,
+`__alignof__' reports the _recommended_ alignment of a type.
+
+ If the operand of `__alignof__' is an lvalue rather than a type, its
+value is the required alignment for its type, taking into account any
+minimum alignment specified with GCC's `__attribute__' extension (*note
+Variable Attributes::). For example, after this declaration:
+
+ struct foo { int x; char y; } foo1;
+
+the value of `__alignof__ (foo1.y)' is 1, even though its actual
+alignment is probably 2 or 4, the same as `__alignof__ (int)'.
+
+ It is an error to ask for the alignment of an incomplete type.
+
+\1f
+File: gcc.info, Node: Variable Attributes, Next: Type Attributes, Prev: Character Escapes, Up: C Extensions
+
+5.32 Specifying Attributes of Variables
+=======================================
+
+The keyword `__attribute__' allows you to specify special attributes of
+variables or structure fields. This keyword is followed by an
+attribute specification inside double parentheses. Ten attributes are
+currently defined for variables: `aligned', `mode', `nocommon',
+`packed', `section', `transparent_union', `unused', `deprecated',
+`vector_size', and `weak'. Some other attributes are defined for
+variables on particular target systems. Other attributes are available
+for functions (*note Function Attributes::) and for types (*note Type
+Attributes::). Other front ends might define more attributes (*note
+Extensions to the C++ Language: C++ Extensions.).
+
+ You may also specify attributes with `__' preceding and following
+each keyword. This allows you to use them in header files without
+being concerned about a possible macro of the same name. For example,
+you may use `__aligned__' instead of `aligned'.
+
+ *Note Attribute Syntax::, for details of the exact syntax for using
+attributes.
+
+`aligned (ALIGNMENT)'
+ This attribute specifies a minimum alignment for the variable or
+ structure field, measured in bytes. For example, the declaration:
+
+ int x __attribute__ ((aligned (16))) = 0;
+
+ causes the compiler to allocate the global variable `x' on a
+ 16-byte boundary. On a 68040, this could be used in conjunction
+ with an `asm' expression to access the `move16' instruction which
+ requires 16-byte aligned operands.
+
+ You can also specify the alignment of structure fields. For
+ example, to create a double-word aligned `int' pair, you could
+ write:
+
+ struct foo { int x[2] __attribute__ ((aligned (8))); };
+
+ This is an alternative to creating a union with a `double' member
+ that forces the union to be double-word aligned.
+
+ As in the preceding examples, you can explicitly specify the
+ alignment (in bytes) that you wish the compiler to use for a given
+ variable or structure field. Alternatively, you can leave out the
+ alignment factor and just ask the compiler to align a variable or
+ field to the maximum useful alignment for the target machine you
+ are compiling for. For example, you could write:
+
+ short array[3] __attribute__ ((aligned));
+
+ Whenever you leave out the alignment factor in an `aligned'
+ attribute specification, the compiler automatically sets the
+ alignment for the declared variable or field to the largest
+ alignment which is ever used for any data type on the target
+ machine you are compiling for. Doing this can often make copy
+ operations more efficient, because the compiler can use whatever
+ instructions copy the biggest chunks of memory when performing
+ copies to or from the variables or fields that you have aligned
+ this way.
+
+ The `aligned' attribute can only increase the alignment; but you
+ can decrease it by specifying `packed' as well. See below.
+
+ Note that the effectiveness of `aligned' attributes may be limited
+ by inherent limitations in your linker. On many systems, the
+ linker is only able to arrange for variables to be aligned up to a
+ certain maximum alignment. (For some linkers, the maximum
+ supported alignment may be very very small.) If your linker is
+ only able to align variables up to a maximum of 8 byte alignment,
+ then specifying `aligned(16)' in an `__attribute__' will still
+ only provide you with 8 byte alignment. See your linker
+ documentation for further information.
+
+`mode (MODE)'
+ This attribute specifies the data type for the
+ declaration--whichever type corresponds to the mode MODE. This in
+ effect lets you request an integer or floating point type
+ according to its width.
+
+ You may also specify a mode of `byte' or `__byte__' to indicate
+ the mode corresponding to a one-byte integer, `word' or `__word__'
+ for the mode of a one-word integer, and `pointer' or `__pointer__'
+ for the mode used to represent pointers.
+
+`nocommon'
+ This attribute specifies requests GCC not to place a variable
+ "common" but instead to allocate space for it directly. If you
+ specify the `-fno-common' flag, GCC will do this for all variables.
+
+ Specifying the `nocommon' attribute for a variable provides an
+ initialization of zeros. A variable may only be initialized in one
+ source file.
+
+`packed'
+ The `packed' attribute specifies that a variable or structure field
+ should have the smallest possible alignment--one byte for a
+ variable, and one bit for a field, unless you specify a larger
+ value with the `aligned' attribute.
+
+ Here is a structure in which the field `x' is packed, so that it
+ immediately follows `a':
+
+ struct foo
+ {
+ char a;
+ int x[2] __attribute__ ((packed));
+ };
+
+`section ("SECTION-NAME")'
+ Normally, the compiler places the objects it generates in sections
+ like `data' and `bss'. Sometimes, however, you need additional
+ sections, or you need certain particular variables to appear in
+ special sections, for example to map to special hardware. The
+ `section' attribute specifies that a variable (or function) lives
+ in a particular section. For example, this small program uses
+ several specific section names:
+
+ struct duart a __attribute__ ((section ("DUART_A"))) = { 0 };
+ struct duart b __attribute__ ((section ("DUART_B"))) = { 0 };
+ char stack[10000] __attribute__ ((section ("STACK"))) = { 0 };
+ int init_data __attribute__ ((section ("INITDATA"))) = 0;
+
+ main()
+ {
+ /* Initialize stack pointer */
+ init_sp (stack + sizeof (stack));
+
+ /* Initialize initialized data */
+ memcpy (&init_data, &data, &edata - &data);
+
+ /* Turn on the serial ports */
+ init_duart (&a);
+ init_duart (&b);
+ }
+
+ Use the `section' attribute with an _initialized_ definition of a
+ _global_ variable, as shown in the example. GCC issues a warning
+ and otherwise ignores the `section' attribute in uninitialized
+ variable declarations.
+
+ You may only use the `section' attribute with a fully initialized
+ global definition because of the way linkers work. The linker
+ requires each object be defined once, with the exception that
+ uninitialized variables tentatively go in the `common' (or `bss')
+ section and can be multiply "defined". You can force a variable
+ to be initialized with the `-fno-common' flag or the `nocommon'
+ attribute.
+
+ Some file formats do not support arbitrary sections so the
+ `section' attribute is not available on all platforms. If you
+ need to map the entire contents of a module to a particular
+ section, consider using the facilities of the linker instead.
+
+`shared'
+ On Windows NT, in addition to putting variable definitions in a
+ named section, the section can also be shared among all running
+ copies of an executable or DLL. For example, this small program
+ defines shared data by putting it in a named section `shared' and
+ marking the section shareable:
+
+ int foo __attribute__((section ("shared"), shared)) = 0;
+
+ int
+ main()
+ {
+ /* Read and write foo. All running
+ copies see the same value. */
+ return 0;
+ }
+
+ You may only use the `shared' attribute along with `section'
+ attribute with a fully initialized global definition because of
+ the way linkers work. See `section' attribute for more
+ information.
+
+ The `shared' attribute is only available on Windows NT.
+
+`transparent_union'
+ This attribute, attached to a function parameter which is a union,
+ means that the corresponding argument may have the type of any
+ union member, but the argument is passed as if its type were that
+ of the first union member. For more details see *Note Type
+ Attributes::. You can also use this attribute on a `typedef' for
+ a union data type; then it applies to all function parameters with
+ that type.
+
+`unused'
+ This attribute, attached to a variable, means that the variable is
+ meant to be possibly unused. GCC will not produce a warning for
+ this variable.
+
+`deprecated'
+ The `deprecated' attribute results in a warning if the variable is
+ used anywhere in the source file. This is useful when identifying
+ variables that are expected to be removed in a future version of a
+ program. The warning also includes the location of the declaration
+ of the deprecated variable, to enable users to easily find further
+ information about why the variable is deprecated, or what they
+ should do instead. Note that the warnings only occurs for uses:
+
+ extern int old_var __attribute__ ((deprecated));
+ extern int old_var;
+ int new_fn () { return old_var; }
+
+ results in a warning on line 3 but not line 2.
+
+ The `deprecated' attribute can also be used for functions and
+ types (*note Function Attributes::, *note Type Attributes::.)
+
+`vector_size (BYTES)'
+ This attribute specifies the vector size for the variable,
+ measured in bytes. For example, the declaration:
+
+ int foo __attribute__ ((vector_size (16)));
+
+ causes the compiler to set the mode for `foo', to be 16 bytes,
+ divided into `int' sized units. Assuming a 32-bit int (a vector of
+ 4 units of 4 bytes), the corresponding mode of `foo' will be V4SI.
+
+ This attribute is only applicable to integral and float scalars,
+ although arrays, pointers, and function return values are allowed
+ in conjunction with this construct.
+
+ Aggregates with this attribute are invalid, even if they are of
+ the same size as a corresponding scalar. For example, the
+ declaration:
+
+ struct S { int a; };
+ struct S __attribute__ ((vector_size (16))) foo;
+
+ is invalid even if the size of the structure is the same as the
+ size of the `int'.
+
+`weak'
+ The `weak' attribute is described in *Note Function Attributes::.
+
+`model (MODEL-NAME)'
+ Use this attribute on the M32R/D to set the addressability of an
+ object. The identifier MODEL-NAME is one of `small', `medium', or
+ `large', representing each of the code models.
+
+ Small model objects live in the lower 16MB of memory (so that their
+ addresses can be loaded with the `ld24' instruction).
+
+ Medium and large model objects may live anywhere in the 32-bit
+ address space (the compiler will generate `seth/add3' instructions
+ to load their addresses).
+
+
+ To specify multiple attributes, separate them by commas within the
+double parentheses: for example, `__attribute__ ((aligned (16),
+packed))'.
+
+\1f
+File: gcc.info, Node: Type Attributes, Next: Alignment, Prev: Variable Attributes, Up: C Extensions
+
+5.33 Specifying Attributes of Types
+===================================
+
+The keyword `__attribute__' allows you to specify special attributes of
+`struct' and `union' types when you define such types. This keyword is
+followed by an attribute specification inside double parentheses. Five
+attributes are currently defined for types: `aligned', `packed',
+`transparent_union', `unused', and `deprecated'. Other attributes are
+defined for functions (*note Function Attributes::) and for variables
+(*note Variable Attributes::).
+
+ You may also specify any one of these attributes with `__' preceding
+and following its keyword. This allows you to use these attributes in
+header files without being concerned about a possible macro of the same
+name. For example, you may use `__aligned__' instead of `aligned'.
+
+ You may specify the `aligned' and `transparent_union' attributes
+either in a `typedef' declaration or just past the closing curly brace
+of a complete enum, struct or union type _definition_ and the `packed'
+attribute only past the closing brace of a definition.
+
+ You may also specify attributes between the enum, struct or union
+tag and the name of the type rather than after the closing brace.
+
+ *Note Attribute Syntax::, for details of the exact syntax for using
+attributes.
+
+`aligned (ALIGNMENT)'
+ This attribute specifies a minimum alignment (in bytes) for
+ variables of the specified type. For example, the declarations:
+
+ struct S { short f[3]; } __attribute__ ((aligned (8)));
+ typedef int more_aligned_int __attribute__ ((aligned (8)));
+
+ force the compiler to insure (as far as it can) that each variable
+ whose type is `struct S' or `more_aligned_int' will be allocated
+ and aligned _at least_ on a 8-byte boundary. On a Sparc, having
+ all variables of type `struct S' aligned to 8-byte boundaries
+ allows the compiler to use the `ldd' and `std' (doubleword load and
+ store) instructions when copying one variable of type `struct S' to
+ another, thus improving run-time efficiency.
+
+ Note that the alignment of any given `struct' or `union' type is
+ required by the ISO C standard to be at least a perfect multiple of
+ the lowest common multiple of the alignments of all of the members
+ of the `struct' or `union' in question. This means that you _can_
+ effectively adjust the alignment of a `struct' or `union' type by
+ attaching an `aligned' attribute to any one of the members of such
+ a type, but the notation illustrated in the example above is a
+ more obvious, intuitive, and readable way to request the compiler
+ to adjust the alignment of an entire `struct' or `union' type.
+
+ As in the preceding example, you can explicitly specify the
+ alignment (in bytes) that you wish the compiler to use for a given
+ `struct' or `union' type. Alternatively, you can leave out the
+ alignment factor and just ask the compiler to align a type to the
+ maximum useful alignment for the target machine you are compiling
+ for. For example, you could write:
+
+ struct S { short f[3]; } __attribute__ ((aligned));
+
+ Whenever you leave out the alignment factor in an `aligned'
+ attribute specification, the compiler automatically sets the
+ alignment for the type to the largest alignment which is ever used
+ for any data type on the target machine you are compiling for.
+ Doing this can often make copy operations more efficient, because
+ the compiler can use whatever instructions copy the biggest chunks
+ of memory when performing copies to or from the variables which
+ have types that you have aligned this way.
+
+ In the example above, if the size of each `short' is 2 bytes, then
+ the size of the entire `struct S' type is 6 bytes. The smallest
+ power of two which is greater than or equal to that is 8, so the
+ compiler sets the alignment for the entire `struct S' type to 8
+ bytes.
+
+ Note that although you can ask the compiler to select a
+ time-efficient alignment for a given type and then declare only
+ individual stand-alone objects of that type, the compiler's
+ ability to select a time-efficient alignment is primarily useful
+ only when you plan to create arrays of variables having the
+ relevant (efficiently aligned) type. If you declare or use arrays
+ of variables of an efficiently-aligned type, then it is likely
+ that your program will also be doing pointer arithmetic (or
+ subscripting, which amounts to the same thing) on pointers to the
+ relevant type, and the code that the compiler generates for these
+ pointer arithmetic operations will often be more efficient for
+ efficiently-aligned types than for other types.
+
+ The `aligned' attribute can only increase the alignment; but you
+ can decrease it by specifying `packed' as well. See below.
+
+ Note that the effectiveness of `aligned' attributes may be limited
+ by inherent limitations in your linker. On many systems, the
+ linker is only able to arrange for variables to be aligned up to a
+ certain maximum alignment. (For some linkers, the maximum
+ supported alignment may be very very small.) If your linker is
+ only able to align variables up to a maximum of 8 byte alignment,
+ then specifying `aligned(16)' in an `__attribute__' will still
+ only provide you with 8 byte alignment. See your linker
+ documentation for further information.
+
+`packed'
+ This attribute, attached to an `enum', `struct', or `union' type
+ definition, specified that the minimum required memory be used to
+ represent the type.
+
+ Specifying this attribute for `struct' and `union' types is
+ equivalent to specifying the `packed' attribute on each of the
+ structure or union members. Specifying the `-fshort-enums' flag
+ on the line is equivalent to specifying the `packed' attribute on
+ all `enum' definitions.
+
+ You may only specify this attribute after a closing curly brace on
+ an `enum' definition, not in a `typedef' declaration, unless that
+ declaration also contains the definition of the `enum'.
+
+`transparent_union'
+ This attribute, attached to a `union' type definition, indicates
+ that any function parameter having that union type causes calls to
+ that function to be treated in a special way.
+
+ First, the argument corresponding to a transparent union type can
+ be of any type in the union; no cast is required. Also, if the
+ union contains a pointer type, the corresponding argument can be a
+ null pointer constant or a void pointer expression; and if the
+ union contains a void pointer type, the corresponding argument can
+ be any pointer expression. If the union member type is a pointer,
+ qualifiers like `const' on the referenced type must be respected,
+ just as with normal pointer conversions.
+
+ Second, the argument is passed to the function using the calling
+ conventions of first member of the transparent union, not the
+ calling conventions of the union itself. All members of the union
+ must have the same machine representation; this is necessary for
+ this argument passing to work properly.
+
+ Transparent unions are designed for library functions that have
+ multiple interfaces for compatibility reasons. For example,
+ suppose the `wait' function must accept either a value of type
+ `int *' to comply with Posix, or a value of type `union wait *' to
+ comply with the 4.1BSD interface. If `wait''s parameter were
+ `void *', `wait' would accept both kinds of arguments, but it
+ would also accept any other pointer type and this would make
+ argument type checking less useful. Instead, `<sys/wait.h>' might
+ define the interface as follows:
+
+ typedef union
+ {
+ int *__ip;
+ union wait *__up;
+ } wait_status_ptr_t __attribute__ ((__transparent_union__));
+
+ pid_t wait (wait_status_ptr_t);
+
+ This interface allows either `int *' or `union wait *' arguments
+ to be passed, using the `int *' calling convention. The program
+ can call `wait' with arguments of either type:
+
+ int w1 () { int w; return wait (&w); }
+ int w2 () { union wait w; return wait (&w); }
+
+ With this interface, `wait''s implementation might look like this:
+
+ pid_t wait (wait_status_ptr_t p)
+ {
+ return waitpid (-1, p.__ip, 0);
+ }
+
+`unused'
+ When attached to a type (including a `union' or a `struct'), this
+ attribute means that variables of that type are meant to appear
+ possibly unused. GCC will not produce a warning for any variables
+ of that type, even if the variable appears to do nothing. This is
+ often the case with lock or thread classes, which are usually
+ defined and then not referenced, but contain constructors and
+ destructors that have nontrivial bookkeeping functions.
+
+`deprecated'
+ The `deprecated' attribute results in a warning if the type is
+ used anywhere in the source file. This is useful when identifying
+ types that are expected to be removed in a future version of a
+ program. If possible, the warning also includes the location of
+ the declaration of the deprecated type, to enable users to easily
+ find further information about why the type is deprecated, or what
+ they should do instead. Note that the warnings only occur for
+ uses and then only if the type is being applied to an identifier
+ that itself is not being declared as deprecated.
+
+ typedef int T1 __attribute__ ((deprecated));
+ T1 x;
+ typedef T1 T2;
+ T2 y;
+ typedef T1 T3 __attribute__ ((deprecated));
+ T3 z __attribute__ ((deprecated));
+
+ results in a warning on line 2 and 3 but not lines 4, 5, or 6. No
+ warning is issued for line 4 because T2 is not explicitly
+ deprecated. Line 5 has no warning because T3 is explicitly
+ deprecated. Similarly for line 6.
+
+ The `deprecated' attribute can also be used for functions and
+ variables (*note Function Attributes::, *note Variable
+ Attributes::.)
+
+
+ To specify multiple attributes, separate them by commas within the
+double parentheses: for example, `__attribute__ ((aligned (16),
+packed))'.
+
+\1f
+File: gcc.info, Node: Inline, Next: Extended Asm, Prev: Alignment, Up: C Extensions
+
+5.34 An Inline Function is As Fast As a Macro
+=============================================
+
+By declaring a function `inline', you can direct GCC to integrate that
+function's code into the code for its callers. This makes execution
+faster by eliminating the function-call overhead; in addition, if any
+of the actual argument values are constant, their known values may
+permit simplifications at compile time so that not all of the inline
+function's code needs to be included. The effect on code size is less
+predictable; object code may be larger or smaller with function
+inlining, depending on the particular case. Inlining of functions is an
+optimization and it really "works" only in optimizing compilation. If
+you don't use `-O', no function is really inline.
+
+ Inline functions are included in the ISO C99 standard, but there are
+currently substantial differences between what GCC implements and what
+the ISO C99 standard requires.
+
+ To declare a function inline, use the `inline' keyword in its
+declaration, like this:
+
+ inline int
+ inc (int *a)
+ {
+ (*a)++;
+ }
+
+ (If you are writing a header file to be included in ISO C programs,
+write `__inline__' instead of `inline'. *Note Alternate Keywords::.)
+You can also make all "simple enough" functions inline with the option
+`-finline-functions'.
+
+ Note that certain usages in a function definition can make it
+unsuitable for inline substitution. Among these usages are: use of
+varargs, use of alloca, use of variable sized data types (*note
+Variable Length::), use of computed goto (*note Labels as Values::),
+use of nonlocal goto, and nested functions (*note Nested Functions::).
+Using `-Winline' will warn when a function marked `inline' could not be
+substituted, and will give the reason for the failure.
+
+ Note that in C and Objective-C, unlike C++, the `inline' keyword
+does not affect the linkage of the function.
+
+ GCC automatically inlines member functions defined within the class
+body of C++ programs even if they are not explicitly declared `inline'.
+(You can override this with `-fno-default-inline'; *note Options
+Controlling C++ Dialect: C++ Dialect Options.)
+
+ When a function is both inline and `static', if all calls to the
+function are integrated into the caller, and the function's address is
+never used, then the function's own assembler code is never referenced.
+In this case, GCC does not actually output assembler code for the
+function, unless you specify the option `-fkeep-inline-functions'.
+Some calls cannot be integrated for various reasons (in particular,
+calls that precede the function's definition cannot be integrated, and
+neither can recursive calls within the definition). If there is a
+nonintegrated call, then the function is compiled to assembler code as
+usual. The function must also be compiled as usual if the program
+refers to its address, because that can't be inlined.
+
+ When an inline function is not `static', then the compiler must
+assume that there may be calls from other source files; since a global
+symbol can be defined only once in any program, the function must not
+be defined in the other source files, so the calls therein cannot be
+integrated. Therefore, a non-`static' inline function is always
+compiled on its own in the usual fashion.
+
+ If you specify both `inline' and `extern' in the function
+definition, then the definition is used only for inlining. In no case
+is the function compiled on its own, not even if you refer to its
+address explicitly. Such an address becomes an external reference, as
+if you had only declared the function, and had not defined it.
+
+ This combination of `inline' and `extern' has almost the effect of a
+macro. The way to use it is to put a function definition in a header
+file with these keywords, and put another copy of the definition
+(lacking `inline' and `extern') in a library file. The definition in
+the header file will cause most calls to the function to be inlined.
+If any uses of the function remain, they will refer to the single copy
+in the library.
+
+ For future compatibility with when GCC implements ISO C99 semantics
+for inline functions, it is best to use `static inline' only. (The
+existing semantics will remain available when `-std=gnu89' is
+specified, but eventually the default will be `-std=gnu99' and that
+will implement the C99 semantics, though it does not do so yet.)
+
+ GCC does not inline any functions when not optimizing unless you
+specify the `always_inline' attribute for the function, like this:
+
+ /* Prototype. */
+ inline void foo (const char) __attribute__((always_inline));
+
+\1f
+File: gcc.info, Node: Extended Asm, Next: Constraints, Prev: Inline, Up: C Extensions
+
+5.35 Assembler Instructions with C Expression Operands
+======================================================
+
+In an assembler instruction using `asm', you can specify the operands
+of the instruction using C expressions. This means you need not guess
+which registers or memory locations will contain the data you want to
+use.
+
+ You must specify an assembler instruction template much like what
+appears in a machine description, plus an operand constraint string for
+each operand.
+
+ For example, here is how to use the 68881's `fsinx' instruction:
+
+ asm ("fsinx %1,%0" : "=f" (result) : "f" (angle));
+
+Here `angle' is the C expression for the input operand while `result'
+is that of the output operand. Each has `"f"' as its operand
+constraint, saying that a floating point register is required. The `='
+in `=f' indicates that the operand is an output; all output operands'
+constraints must use `='. The constraints use the same language used
+in the machine description (*note Constraints::).
+
+ Each operand is described by an operand-constraint string followed by
+the C expression in parentheses. A colon separates the assembler
+template from the first output operand and another separates the last
+output operand from the first input, if any. Commas separate the
+operands within each group. The total number of operands is currently
+limited to 30; this limitation may be lifted in some future version of
+GCC.
+
+ If there are no output operands but there are input operands, you
+must place two consecutive colons surrounding the place where the output
+operands would go.
+
+ As of GCC version 3.1, it is also possible to specify input and
+output operands using symbolic names which can be referenced within the
+assembler code. These names are specified inside square brackets
+preceding the constraint string, and can be referenced inside the
+assembler code using `%[NAME]' instead of a percentage sign followed by
+the operand number. Using named operands the above example could look
+like:
+
+ asm ("fsinx %[angle],%[output]"
+ : [output] "=f" (result)
+ : [angle] "f" (angle));
+
+Note that the symbolic operand names have no relation whatsoever to
+other C identifiers. You may use any name you like, even those of
+existing C symbols, but must ensure that no two operands within the same
+assembler construct use the same symbolic name.
+
+ Output operand expressions must be lvalues; the compiler can check
+this. The input operands need not be lvalues. The compiler cannot
+check whether the operands have data types that are reasonable for the
+instruction being executed. It does not parse the assembler instruction
+template and does not know what it means or even whether it is valid
+assembler input. The extended `asm' feature is most often used for
+machine instructions the compiler itself does not know exist. If the
+output expression cannot be directly addressed (for example, it is a
+bit-field), your constraint must allow a register. In that case, GCC
+will use the register as the output of the `asm', and then store that
+register into the output.
+
+ The ordinary output operands must be write-only; GCC will assume that
+the values in these operands before the instruction are dead and need
+not be generated. Extended asm supports input-output or read-write
+operands. Use the constraint character `+' to indicate such an operand
+and list it with the output operands.
+
+ When the constraints for the read-write operand (or the operand in
+which only some of the bits are to be changed) allows a register, you
+may, as an alternative, logically split its function into two separate
+operands, one input operand and one write-only output operand. The
+connection between them is expressed by constraints which say they need
+to be in the same location when the instruction executes. You can use
+the same C expression for both operands, or different expressions. For
+example, here we write the (fictitious) `combine' instruction with
+`bar' as its read-only source operand and `foo' as its read-write
+destination:
+
+ asm ("combine %2,%0" : "=r" (foo) : "0" (foo), "g" (bar));
+
+The constraint `"0"' for operand 1 says that it must occupy the same
+location as operand 0. A number in constraint is allowed only in an
+input operand and it must refer to an output operand.
+
+ Only a number in the constraint can guarantee that one operand will
+be in the same place as another. The mere fact that `foo' is the value
+of both operands is not enough to guarantee that they will be in the
+same place in the generated assembler code. The following would not
+work reliably:
+
+ asm ("combine %2,%0" : "=r" (foo) : "r" (foo), "g" (bar));
+
+ Various optimizations or reloading could cause operands 0 and 1 to
+be in different registers; GCC knows no reason not to do so. For
+example, the compiler might find a copy of the value of `foo' in one
+register and use it for operand 1, but generate the output operand 0 in
+a different register (copying it afterward to `foo''s own address). Of
+course, since the register for operand 1 is not even mentioned in the
+assembler code, the result will not work, but GCC can't tell that.
+
+ As of GCC version 3.1, one may write `[NAME]' instead of the operand
+number for a matching constraint. For example:
+
+ asm ("cmoveq %1,%2,%[result]"
+ : [result] "=r"(result)
+ : "r" (test), "r"(new), "[result]"(old));
+
+ Some instructions clobber specific hard registers. To describe this,
+write a third colon after the input operands, followed by the names of
+the clobbered hard registers (given as strings). Here is a realistic
+example for the VAX:
+
+ asm volatile ("movc3 %0,%1,%2"
+ : /* no outputs */
+ : "g" (from), "g" (to), "g" (count)
+ : "r0", "r1", "r2", "r3", "r4", "r5");
+
+ You may not write a clobber description in a way that overlaps with
+an input or output operand. For example, you may not have an operand
+describing a register class with one member if you mention that register
+in the clobber list. There is no way for you to specify that an input
+operand is modified without also specifying it as an output operand.
+Note that if all the output operands you specify are for this purpose
+(and hence unused), you will then also need to specify `volatile' for
+the `asm' construct, as described below, to prevent GCC from deleting
+the `asm' statement as unused.
+
+ If you refer to a particular hardware register from the assembler
+code, you will probably have to list the register after the third colon
+to tell the compiler the register's value is modified. In some
+assemblers, the register names begin with `%'; to produce one `%' in the
+assembler code, you must write `%%' in the input.
+
+ If your assembler instruction can alter the condition code register,
+add `cc' to the list of clobbered registers. GCC on some machines
+represents the condition codes as a specific hardware register; `cc'
+serves to name this register. On other machines, the condition code is
+handled differently, and specifying `cc' has no effect. But it is
+valid no matter what the machine.
+
+ If your assembler instruction modifies memory in an unpredictable
+fashion, add `memory' to the list of clobbered registers. This will
+cause GCC to not keep memory values cached in registers across the
+assembler instruction. You will also want to add the `volatile'
+keyword if the memory affected is not listed in the inputs or outputs
+of the `asm', as the `memory' clobber does not count as a side-effect
+of the `asm'.
+
+ You can put multiple assembler instructions together in a single
+`asm' template, separated by the characters normally used in assembly
+code for the system. A combination that works in most places is a
+newline to break the line, plus a tab character to move to the
+instruction field (written as `\n\t'). Sometimes semicolons can be
+used, if the assembler allows semicolons as a line-breaking character.
+Note that some assembler dialects use semicolons to start a comment.
+The input operands are guaranteed not to use any of the clobbered
+registers, and neither will the output operands' addresses, so you can
+read and write the clobbered registers as many times as you like. Here
+is an example of multiple instructions in a template; it assumes the
+subroutine `_foo' accepts arguments in registers 9 and 10:
+
+ asm ("movl %0,r9\n\tmovl %1,r10\n\tcall _foo"
+ : /* no outputs */
+ : "g" (from), "g" (to)
+ : "r9", "r10");
+
+ Unless an output operand has the `&' constraint modifier, GCC may
+allocate it in the same register as an unrelated input operand, on the
+assumption the inputs are consumed before the outputs are produced.
+This assumption may be false if the assembler code actually consists of
+more than one instruction. In such a case, use `&' for each output
+operand that may not overlap an input. *Note Modifiers::.
+
+ If you want to test the condition code produced by an assembler
+instruction, you must include a branch and a label in the `asm'
+construct, as follows:
+
+ asm ("clr %0\n\tfrob %1\n\tbeq 0f\n\tmov #1,%0\n0:"
+ : "g" (result)
+ : "g" (input));
+
+This assumes your assembler supports local labels, as the GNU assembler
+and most Unix assemblers do.
+
+ Speaking of labels, jumps from one `asm' to another are not
+supported. The compiler's optimizers do not know about these jumps, and
+therefore they cannot take account of them when deciding how to
+optimize.
+
+ Usually the most convenient way to use these `asm' instructions is to
+encapsulate them in macros that look like functions. For example,
+
+ #define sin(x) \
+ ({ double __value, __arg = (x); \
+ asm ("fsinx %1,%0": "=f" (__value): "f" (__arg)); \
+ __value; })
+
+Here the variable `__arg' is used to make sure that the instruction
+operates on a proper `double' value, and to accept only those arguments
+`x' which can convert automatically to a `double'.
+
+ Another way to make sure the instruction operates on the correct data
+type is to use a cast in the `asm'. This is different from using a
+variable `__arg' in that it converts more different types. For
+example, if the desired type were `int', casting the argument to `int'
+would accept a pointer with no complaint, while assigning the argument
+to an `int' variable named `__arg' would warn about using a pointer
+unless the caller explicitly casts it.
+
+ If an `asm' has output operands, GCC assumes for optimization
+purposes the instruction has no side effects except to change the output
+operands. This does not mean instructions with a side effect cannot be
+used, but you must be careful, because the compiler may eliminate them
+if the output operands aren't used, or move them out of loops, or
+replace two with one if they constitute a common subexpression. Also,
+if your instruction does have a side effect on a variable that otherwise
+appears not to change, the old value of the variable may be reused later
+if it happens to be found in a register.
+
+ You can prevent an `asm' instruction from being deleted, moved
+significantly, or combined, by writing the keyword `volatile' after the
+`asm'. For example:
+
+ #define get_and_set_priority(new) \
+ ({ int __old; \
+ asm volatile ("get_and_set_priority %0, %1" \
+ : "=g" (__old) : "g" (new)); \
+ __old; })
+
+If you write an `asm' instruction with no outputs, GCC will know the
+instruction has side-effects and will not delete the instruction or
+move it outside of loops.
+
+ The `volatile' keyword indicates that the instruction has important
+side-effects. GCC will not delete a volatile `asm' if it is reachable.
+(The instruction can still be deleted if GCC can prove that
+control-flow will never reach the location of the instruction.) In
+addition, GCC will not reschedule instructions across a volatile `asm'
+instruction. For example:
+
+ *(volatile int *)addr = foo;
+ asm volatile ("eieio" : : );
+
+Assume `addr' contains the address of a memory mapped device register.
+The PowerPC `eieio' instruction (Enforce In-order Execution of I/O)
+tells the CPU to make sure that the store to that device register
+happens before it issues any other I/O.
+
+ Note that even a volatile `asm' instruction can be moved in ways
+that appear insignificant to the compiler, such as across jump
+instructions. You can't expect a sequence of volatile `asm'
+instructions to remain perfectly consecutive. If you want consecutive
+output, use a single `asm'. Also, GCC will perform some optimizations
+across a volatile `asm' instruction; GCC does not "forget everything"
+when it encounters a volatile `asm' instruction the way some other
+compilers do.
+
+ An `asm' instruction without any operands or clobbers (an "old
+style" `asm') will be treated identically to a volatile `asm'
+instruction.
+
+ It is a natural idea to look for a way to give access to the
+condition code left by the assembler instruction. However, when we
+attempted to implement this, we found no way to make it work reliably.
+The problem is that output operands might need reloading, which would
+result in additional following "store" instructions. On most machines,
+these instructions would alter the condition code before there was time
+to test it. This problem doesn't arise for ordinary "test" and
+"compare" instructions because they don't have any output operands.
+
+ For reasons similar to those described above, it is not possible to
+give an assembler instruction access to the condition code left by
+previous instructions.
+
+ If you are writing a header file that should be includable in ISO C
+programs, write `__asm__' instead of `asm'. *Note Alternate Keywords::.
+
+5.35.1 i386 floating point asm operands
+---------------------------------------
+
+There are several rules on the usage of stack-like regs in asm_operands
+insns. These rules apply only to the operands that are stack-like regs:
+
+ 1. Given a set of input regs that die in an asm_operands, it is
+ necessary to know which are implicitly popped by the asm, and
+ which must be explicitly popped by gcc.
+
+ An input reg that is implicitly popped by the asm must be
+ explicitly clobbered, unless it is constrained to match an output
+ operand.
+
+ 2. For any input reg that is implicitly popped by an asm, it is
+ necessary to know how to adjust the stack to compensate for the
+ pop. If any non-popped input is closer to the top of the
+ reg-stack than the implicitly popped reg, it would not be possible
+ to know what the stack looked like--it's not clear how the rest of
+ the stack "slides up".
+
+ All implicitly popped input regs must be closer to the top of the
+ reg-stack than any input that is not implicitly popped.
+
+ It is possible that if an input dies in an insn, reload might use
+ the input reg for an output reload. Consider this example:
+
+ asm ("foo" : "=t" (a) : "f" (b));
+
+ This asm says that input B is not popped by the asm, and that the
+ asm pushes a result onto the reg-stack, i.e., the stack is one
+ deeper after the asm than it was before. But, it is possible that
+ reload will think that it can use the same reg for both the input
+ and the output, if input B dies in this insn.
+
+ If any input operand uses the `f' constraint, all output reg
+ constraints must use the `&' earlyclobber.
+
+ The asm above would be written as
+
+ asm ("foo" : "=&t" (a) : "f" (b));
+
+ 3. Some operands need to be in particular places on the stack. All
+ output operands fall in this category--there is no other way to
+ know which regs the outputs appear in unless the user indicates
+ this in the constraints.
+
+ Output operands must specifically indicate which reg an output
+ appears in after an asm. `=f' is not allowed: the operand
+ constraints must select a class with a single reg.
+
+ 4. Output operands may not be "inserted" between existing stack regs.
+ Since no 387 opcode uses a read/write operand, all output operands
+ are dead before the asm_operands, and are pushed by the
+ asm_operands. It makes no sense to push anywhere but the top of
+ the reg-stack.
+
+ Output operands must start at the top of the reg-stack: output
+ operands may not "skip" a reg.
+
+ 5. Some asm statements may need extra stack space for internal
+ calculations. This can be guaranteed by clobbering stack registers
+ unrelated to the inputs and outputs.
+
+
+ Here are a couple of reasonable asms to want to write. This asm
+takes one input, which is internally popped, and produces two outputs.
+
+ asm ("fsincos" : "=t" (cos), "=u" (sin) : "0" (inp));
+
+ This asm takes two inputs, which are popped by the `fyl2xp1' opcode,
+and replaces them with one output. The user must code the `st(1)'
+clobber for reg-stack.c to know that `fyl2xp1' pops both inputs.
+
+ asm ("fyl2xp1" : "=t" (result) : "0" (x), "u" (y) : "st(1)");
+
+\1f
+File: gcc.info, Node: Constraints, Next: Asm Labels, Prev: Extended Asm, Up: C Extensions
+
+5.36 Constraints for `asm' Operands
+===================================
+
+Here are specific details on what constraint letters you can use with
+`asm' operands. Constraints can say whether an operand may be in a
+register, and which kinds of register; whether the operand can be a
+memory reference, and which kinds of address; whether the operand may
+be an immediate constant, and which possible values it may have.
+Constraints can also require two operands to match.
+
+* Menu:
+
+* Simple Constraints:: Basic use of constraints.
+* Multi-Alternative:: When an insn has two alternative constraint-patterns.
+* Modifiers:: More precise control over effects of constraints.
+* Machine Constraints:: Special constraints for some particular machines.
+
+\1f
+File: gcc.info, Node: Simple Constraints, Next: Multi-Alternative, Up: Constraints
+
+5.36.1 Simple Constraints
+-------------------------
+
+The simplest kind of constraint is a string full of letters, each of
+which describes one kind of operand that is permitted. Here are the
+letters that are allowed:
+
+whitespace
+ Whitespace characters are ignored and can be inserted at any
+ position except the first. This enables each alternative for
+ different operands to be visually aligned in the machine
+ description even if they have different number of constraints and
+ modifiers.
+
+`m'
+ A memory operand is allowed, with any kind of address that the
+ machine supports in general.
+
+`o'
+ A memory operand is allowed, but only if the address is
+ "offsettable". This means that adding a small integer (actually,
+ the width in bytes of the operand, as determined by its machine
+ mode) may be added to the address and the result is also a valid
+ memory address.
+
+ For example, an address which is constant is offsettable; so is an
+ address that is the sum of a register and a constant (as long as a
+ slightly larger constant is also within the range of
+ address-offsets supported by the machine); but an autoincrement or
+ autodecrement address is not offsettable. More complicated
+ indirect/indexed addresses may or may not be offsettable depending
+ on the other addressing modes that the machine supports.
+
+ Note that in an output operand which can be matched by another
+ operand, the constraint letter `o' is valid only when accompanied
+ by both `<' (if the target machine has predecrement addressing)
+ and `>' (if the target machine has preincrement addressing).
+
+`V'
+ A memory operand that is not offsettable. In other words,
+ anything that would fit the `m' constraint but not the `o'
+ constraint.
+
+`<'
+ A memory operand with autodecrement addressing (either
+ predecrement or postdecrement) is allowed.
+
+`>'
+ A memory operand with autoincrement addressing (either
+ preincrement or postincrement) is allowed.
+
+`r'
+ A register operand is allowed provided that it is in a general
+ register.
+
+`i'
+ An immediate integer operand (one with constant value) is allowed.
+ This includes symbolic constants whose values will be known only at
+ assembly time.
+
+`n'
+ An immediate integer operand with a known numeric value is allowed.
+ Many systems cannot support assembly-time constants for operands
+ less than a word wide. Constraints for these operands should use
+ `n' rather than `i'.
+
+`I', `J', `K', ... `P'
+ Other letters in the range `I' through `P' may be defined in a
+ machine-dependent fashion to permit immediate integer operands with
+ explicit integer values in specified ranges. For example, on the
+ 68000, `I' is defined to stand for the range of values 1 to 8.
+ This is the range permitted as a shift count in the shift
+ instructions.
+
+`E'
+ An immediate floating operand (expression code `const_double') is
+ allowed, but only if the target floating point format is the same
+ as that of the host machine (on which the compiler is running).
+
+`F'
+ An immediate floating operand (expression code `const_double') is
+ allowed.
+
+`G', `H'
+ `G' and `H' may be defined in a machine-dependent fashion to
+ permit immediate floating operands in particular ranges of values.
+
+`s'
+ An immediate integer operand whose value is not an explicit
+ integer is allowed.
+
+ This might appear strange; if an insn allows a constant operand
+ with a value not known at compile time, it certainly must allow
+ any known value. So why use `s' instead of `i'? Sometimes it
+ allows better code to be generated.
+
+ For example, on the 68000 in a fullword instruction it is possible
+ to use an immediate operand; but if the immediate value is between
+ -128 and 127, better code results from loading the value into a
+ register and using the register. This is because the load into
+ the register can be done with a `moveq' instruction. We arrange
+ for this to happen by defining the letter `K' to mean "any integer
+ outside the range -128 to 127", and then specifying `Ks' in the
+ operand constraints.
+
+`g'
+ Any register, memory or immediate integer operand is allowed,
+ except for registers that are not general registers.
+
+`X'
+ Any operand whatsoever is allowed.
+
+`0', `1', `2', ... `9'
+ An operand that matches the specified operand number is allowed.
+ If a digit is used together with letters within the same
+ alternative, the digit should come last.
+
+ This number is allowed to be more than a single digit. If multiple
+ digits are encountered consecutavely, they are interpreted as a
+ single decimal integer. There is scant chance for ambiguity,
+ since to-date it has never been desirable that `10' be interpreted
+ as matching either operand 1 _or_ operand 0. Should this be
+ desired, one can use multiple alternatives instead.
+
+ This is called a "matching constraint" and what it really means is
+ that the assembler has only a single operand that fills two roles
+ which `asm' distinguishes. For example, an add instruction uses
+ two input operands and an output operand, but on most CISC
+ machines an add instruction really has only two operands, one of
+ them an input-output operand:
+
+ addl #35,r12
+
+ Matching constraints are used in these circumstances. More
+ precisely, the two operands that match must include one input-only
+ operand and one output-only operand. Moreover, the digit must be a
+ smaller number than the number of the operand that uses it in the
+ constraint.
+
+`p'
+ An operand that is a valid memory address is allowed. This is for
+ "load address" and "push address" instructions.
+
+ `p' in the constraint must be accompanied by `address_operand' as
+ the predicate in the `match_operand'. This predicate interprets
+ the mode specified in the `match_operand' as the mode of the memory
+ reference for which the address would be valid.
+
+OTHER-LETTERS
+ Other letters can be defined in machine-dependent fashion to stand
+ for particular classes of registers or other arbitrary operand
+ types. `d', `a' and `f' are defined on the 68000/68020 to stand
+ for data, address and floating point registers.
+
+
+\1f
+File: gcc.info, Node: Multi-Alternative, Next: Modifiers, Prev: Simple Constraints, Up: Constraints
+
+5.36.2 Multiple Alternative Constraints
+---------------------------------------
+
+Sometimes a single instruction has multiple alternative sets of possible
+operands. For example, on the 68000, a logical-or instruction can
+combine register or an immediate value into memory, or it can combine
+any kind of operand into a register; but it cannot combine one memory
+location into another.
+
+ These constraints are represented as multiple alternatives. An
+alternative can be described by a series of letters for each operand.
+The overall constraint for an operand is made from the letters for this
+operand from the first alternative, a comma, the letters for this
+operand from the second alternative, a comma, and so on until the last
+alternative.
+
+ If all the operands fit any one alternative, the instruction is
+valid. Otherwise, for each alternative, the compiler counts how many
+instructions must be added to copy the operands so that that
+alternative applies. The alternative requiring the least copying is
+chosen. If two alternatives need the same amount of copying, the one
+that comes first is chosen. These choices can be altered with the `?'
+and `!' characters:
+
+`?'
+ Disparage slightly the alternative that the `?' appears in, as a
+ choice when no alternative applies exactly. The compiler regards
+ this alternative as one unit more costly for each `?' that appears
+ in it.
+
+`!'
+ Disparage severely the alternative that the `!' appears in. This
+ alternative can still be used if it fits without reloading, but if
+ reloading is needed, some other alternative will be used.
+
+\1f
+File: gcc.info, Node: Modifiers, Next: Machine Constraints, Prev: Multi-Alternative, Up: Constraints
+
+5.36.3 Constraint Modifier Characters
+-------------------------------------
+
+Here are constraint modifier characters.
+
+`='
+ Means that this operand is write-only for this instruction: the
+ previous value is discarded and replaced by output data.
+
+`+'
+ Means that this operand is both read and written by the
+ instruction.
+
+ When the compiler fixes up the operands to satisfy the constraints,
+ it needs to know which operands are inputs to the instruction and
+ which are outputs from it. `=' identifies an output; `+'
+ identifies an operand that is both input and output; all other
+ operands are assumed to be input only.
+
+ If you specify `=' or `+' in a constraint, you put it in the first
+ character of the constraint string.
+
+`&'
+ Means (in a particular alternative) that this operand is an
+ "earlyclobber" operand, which is modified before the instruction is
+ finished using the input operands. Therefore, this operand may
+ not lie in a register that is used as an input operand or as part
+ of any memory address.
+
+ `&' applies only to the alternative in which it is written. In
+ constraints with multiple alternatives, sometimes one alternative
+ requires `&' while others do not. See, for example, the `movdf'
+ insn of the 68000.
+
+ An input operand can be tied to an earlyclobber operand if its only
+ use as an input occurs before the early result is written. Adding
+ alternatives of this form often allows GCC to produce better code
+ when only some of the inputs can be affected by the earlyclobber.
+ See, for example, the `mulsi3' insn of the ARM.
+
+ `&' does not obviate the need to write `='.
+
+`%'
+ Declares the instruction to be commutative for this operand and the
+ following operand. This means that the compiler may interchange
+ the two operands if that is the cheapest way to make all operands
+ fit the constraints.
+
+`#'
+ Says that all following characters, up to the next comma, are to be
+ ignored as a constraint. They are significant only for choosing
+ register preferences.
+
+`*'
+ Says that the following character should be ignored when choosing
+ register preferences. `*' has no effect on the meaning of the
+ constraint as a constraint, and no effect on reloading.
+
+
+\1f
+File: gcc.info, Node: Machine Constraints, Prev: Modifiers, Up: Constraints
+
+5.36.4 Constraints for Particular Machines
+------------------------------------------
+
+Whenever possible, you should use the general-purpose constraint letters
+in `asm' arguments, since they will convey meaning more readily to
+people reading your code. Failing that, use the constraint letters
+that usually have very similar meanings across architectures. The most
+commonly used constraints are `m' and `r' (for memory and
+general-purpose registers respectively; *note Simple Constraints::), and
+`I', usually the letter indicating the most common immediate-constant
+format.
+
+ For each machine architecture, the `config/MACHINE/MACHINE.h' file
+defines additional constraints. These constraints are used by the
+compiler itself for instruction generation, as well as for `asm'
+statements; therefore, some of the constraints are not particularly
+interesting for `asm'. The constraints are defined through these
+macros:
+
+`REG_CLASS_FROM_LETTER'
+ Register class constraints (usually lower case).
+
+`CONST_OK_FOR_LETTER_P'
+ Immediate constant constraints, for non-floating point constants of
+ word size or smaller precision (usually upper case).
+
+`CONST_DOUBLE_OK_FOR_LETTER_P'
+ Immediate constant constraints, for all floating point constants
+ and for constants of greater than word size precision (usually
+ upper case).
+
+`EXTRA_CONSTRAINT'
+ Special cases of registers or memory. This macro is not required,
+ and is only defined for some machines.
+
+ Inspecting these macro definitions in the compiler source for your
+machine is the best way to be certain you have the right constraints.
+However, here is a summary of the machine-dependent constraints
+available on some particular machines.
+
+_ARM family--`arm.h'_
+
+ `f'
+ Floating-point register
+
+ `F'
+ One of the floating-point constants 0.0, 0.5, 1.0, 2.0, 3.0,
+ 4.0, 5.0 or 10.0
+
+ `G'
+ Floating-point constant that would satisfy the constraint `F'
+ if it were negated
+
+ `I'
+ Integer that is valid as an immediate operand in a data
+ processing instruction. That is, an integer in the range 0
+ to 255 rotated by a multiple of 2
+
+ `J'
+ Integer in the range -4095 to 4095
+
+ `K'
+ Integer that satisfies constraint `I' when inverted (ones
+ complement)
+
+ `L'
+ Integer that satisfies constraint `I' when negated (twos
+ complement)
+
+ `M'
+ Integer in the range 0 to 32
+
+ `Q'
+ A memory reference where the exact address is in a single
+ register (``m'' is preferable for `asm' statements)
+
+ `R'
+ An item in the constant pool
+
+ `S'
+ A symbol in the text segment of the current file
+
+_AMD 29000 family--`a29k.h'_
+
+ `l'
+ Local register 0
+
+ `b'
+ Byte Pointer (`BP') register
+
+ `q'
+ `Q' register
+
+ `h'
+ Special purpose register
+
+ `A'
+ First accumulator register
+
+ `a'
+ Other accumulator register
+
+ `f'
+ Floating point register
+
+ `I'
+ Constant greater than 0, less than 0x100
+
+ `J'
+ Constant greater than 0, less than 0x10000
+
+ `K'
+ Constant whose high 24 bits are on (1)
+
+ `L'
+ 16-bit constant whose high 8 bits are on (1)
+
+ `M'
+ 32-bit constant whose high 16 bits are on (1)
+
+ `N'
+ 32-bit negative constant that fits in 8 bits
+
+ `O'
+ The constant 0x80000000 or, on the 29050, any 32-bit constant
+ whose low 16 bits are 0.
+
+ `P'
+ 16-bit negative constant that fits in 8 bits
+
+ `G'
+ `H'
+ A floating point constant (in `asm' statements, use the
+ machine independent `E' or `F' instead)
+
+_AVR family--`avr.h'_
+
+ `l'
+ Registers from r0 to r15
+
+ `a'
+ Registers from r16 to r23
+
+ `d'
+ Registers from r16 to r31
+
+ `w'
+ Registers from r24 to r31. These registers can be used in
+ `adiw' command
+
+ `e'
+ Pointer register (r26-r31)
+
+ `b'
+ Base pointer register (r28-r31)
+
+ `q'
+ Stack pointer register (SPH:SPL)
+
+ `t'
+ Temporary register r0
+
+ `x'
+ Register pair X (r27:r26)
+
+ `y'
+ Register pair Y (r29:r28)
+
+ `z'
+ Register pair Z (r31:r30)
+
+ `I'
+ Constant greater than -1, less than 64
+
+ `J'
+ Constant greater than -64, less than 1
+
+ `K'
+ Constant integer 2
+
+ `L'
+ Constant integer 0
+
+ `M'
+ Constant that fits in 8 bits
+
+ `N'
+ Constant integer -1
+
+ `O'
+ Constant integer 8, 16, or 24
+
+ `P'
+ Constant integer 1
+
+ `G'
+ A floating point constant 0.0
+
+_IBM RS6000--`rs6000.h'_
+
+ `b'
+ Address base register
+
+ `f'
+ Floating point register
+
+ `h'
+ `MQ', `CTR', or `LINK' register
+
+ `q'
+ `MQ' register
+
+ `c'
+ `CTR' register
+
+ `l'
+ `LINK' register
+
+ `x'
+ `CR' register (condition register) number 0
+
+ `y'
+ `CR' register (condition register)
+
+ `z'
+ `FPMEM' stack memory for FPR-GPR transfers
+
+ `I'
+ Signed 16-bit constant
+
+ `J'
+ Unsigned 16-bit constant shifted left 16 bits (use `L'
+ instead for `SImode' constants)
+
+ `K'
+ Unsigned 16-bit constant
+
+ `L'
+ Signed 16-bit constant shifted left 16 bits
+
+ `M'
+ Constant larger than 31
+
+ `N'
+ Exact power of 2
+
+ `O'
+ Zero
+
+ `P'
+ Constant whose negation is a signed 16-bit constant
+
+ `G'
+ Floating point constant that can be loaded into a register
+ with one instruction per word
+
+ `Q'
+ Memory operand that is an offset from a register (`m' is
+ preferable for `asm' statements)
+
+ `R'
+ AIX TOC entry
+
+ `S'
+ Constant suitable as a 64-bit mask operand
+
+ `T'
+ Constant suitable as a 32-bit mask operand
+
+ `U'
+ System V Release 4 small data area reference
+
+_Intel 386--`i386.h'_
+
+ `q'
+ `a', `b', `c', or `d' register for the i386. For x86-64 it
+ is equivalent to `r' class. (for 8-bit instructions that do
+ not use upper halves)
+
+ `Q'
+ `a', `b', `c', or `d' register. (for 8-bit instructions, that
+ do use upper halves)
+
+ `R'
+ Legacy register--equivalent to `r' class in i386 mode. (for
+ non-8-bit registers used together with 8-bit upper halves in
+ a single instruction)
+
+ `A'
+ Specifies the `a' or `d' registers. This is primarily useful
+ for 64-bit integer values (when in 32-bit mode) intended to
+ be returned with the `d' register holding the most
+ significant bits and the `a' register holding the least
+ significant bits.
+
+ `f'
+ Floating point register
+
+ `t'
+ First (top of stack) floating point register
+
+ `u'
+ Second floating point register
+
+ `a'
+ `a' register
+
+ `b'
+ `b' register
+
+ `c'
+ `c' register
+
+ `d'
+ `d' register
+
+ `D'
+ `di' register
+
+ `S'
+ `si' register
+
+ `x'
+ `xmm' SSE register
+
+ `y'
+ MMX register
+
+ `I'
+ Constant in range 0 to 31 (for 32-bit shifts)
+
+ `J'
+ Constant in range 0 to 63 (for 64-bit shifts)
+
+ `K'
+ `0xff'
+
+ `L'
+ `0xffff'
+
+ `M'
+ 0, 1, 2, or 3 (shifts for `lea' instruction)
+
+ `N'
+ Constant in range 0 to 255 (for `out' instruction)
+
+ `Z'
+ Constant in range 0 to `0xffffffff' or symbolic reference
+ known to fit specified range. (for using immediates in zero
+ extending 32-bit to 64-bit x86-64 instructions)
+
+ `e'
+ Constant in range -2147483648 to 2147483647 or symbolic
+ reference known to fit specified range. (for using
+ immediates in 64-bit x86-64 instructions)
+
+ `G'
+ Standard 80387 floating point constant
+
+_Intel 960--`i960.h'_
+
+ `f'
+ Floating point register (`fp0' to `fp3')
+
+ `l'
+ Local register (`r0' to `r15')
+
+ `b'
+ Global register (`g0' to `g15')
+
+ `d'
+ Any local or global register
+
+ `I'
+ Integers from 0 to 31
+
+ `J'
+ 0
+
+ `K'
+ Integers from -31 to 0
+
+ `G'
+ Floating point 0
+
+ `H'
+ Floating point 1
+
+_MIPS--`mips.h'_
+
+ `d'
+ General-purpose integer register
+
+ `f'
+ Floating-point register (if available)
+
+ `h'
+ `Hi' register
+
+ `l'
+ `Lo' register
+
+ `x'
+ `Hi' or `Lo' register
+
+ `y'
+ General-purpose integer register
+
+ `z'
+ Floating-point status register
+
+ `I'
+ Signed 16-bit constant (for arithmetic instructions)
+
+ `J'
+ Zero
+
+ `K'
+ Zero-extended 16-bit constant (for logic instructions)
+
+ `L'
+ Constant with low 16 bits zero (can be loaded with `lui')
+
+ `M'
+ 32-bit constant which requires two instructions to load (a
+ constant which is not `I', `K', or `L')
+
+ `N'
+ Negative 16-bit constant
+
+ `O'
+ Exact power of two
+
+ `P'
+ Positive 16-bit constant
+
+ `G'
+ Floating point zero
+
+ `Q'
+ Memory reference that can be loaded with more than one
+ instruction (`m' is preferable for `asm' statements)
+
+ `R'
+ Memory reference that can be loaded with one instruction (`m'
+ is preferable for `asm' statements)
+
+ `S'
+ Memory reference in external OSF/rose PIC format (`m' is
+ preferable for `asm' statements)
+
+_Motorola 680x0--`m68k.h'_
+
+ `a'
+ Address register
+
+ `d'
+ Data register
+
+ `f'
+ 68881 floating-point register, if available
+
+ `x'
+ Sun FPA (floating-point) register, if available
+
+ `y'
+ First 16 Sun FPA registers, if available
+
+ `I'
+ Integer in the range 1 to 8
+
+ `J'
+ 16-bit signed number
+
+ `K'
+ Signed number whose magnitude is greater than 0x80
+
+ `L'
+ Integer in the range -8 to -1
+
+ `M'
+ Signed number whose magnitude is greater than 0x100
+
+ `G'
+ Floating point constant that is not a 68881 constant
+
+ `H'
+ Floating point constant that can be used by Sun FPA
+
+_Motorola 68HC11 & 68HC12 families--`m68hc11.h'_
+
+ `a'
+ Register 'a'
+
+ `b'
+ Register 'b'
+
+ `d'
+ Register 'd'
+
+ `q'
+ An 8-bit register
+
+ `t'
+ Temporary soft register _.tmp
+
+ `u'
+ A soft register _.d1 to _.d31
+
+ `w'
+ Stack pointer register
+
+ `x'
+ Register 'x'
+
+ `y'
+ Register 'y'
+
+ `z'
+ Pseudo register 'z' (replaced by 'x' or 'y' at the end)
+
+ `A'
+ An address register: x, y or z
+
+ `B'
+ An address register: x or y
+
+ `D'
+ Register pair (x:d) to form a 32-bit value
+
+ `L'
+ Constants in the range -65536 to 65535
+
+ `M'
+ Constants whose 16-bit low part is zero
+
+ `N'
+ Constant integer 1 or -1
+
+ `O'
+ Constant integer 16
+
+ `P'
+ Constants in the range -8 to 2
+
+
+_SPARC--`sparc.h'_
+
+ `f'
+ Floating-point register that can hold 32- or 64-bit values.
+
+ `e'
+ Floating-point register that can hold 64- or 128-bit values.
+
+ `I'
+ Signed 13-bit constant
+
+ `J'
+ Zero
+
+ `K'
+ 32-bit constant with the low 12 bits clear (a constant that
+ can be loaded with the `sethi' instruction)
+
+ `L'
+ A constant in the range supported by `movcc' instructions
+
+ `M'
+ A constant in the range supported by `movrcc' instructions
+
+ `N'
+ Same as `K', except that it verifies that bits that are not
+ in the lower 32-bit range are all zero. Must be used instead
+ of `K' for modes wider than `SImode'
+
+ `G'
+ Floating-point zero
+
+ `H'
+ Signed 13-bit constant, sign-extended to 32 or 64 bits
+
+ `Q'
+ Floating-point constant whose integral representation can be
+ moved into an integer register using a single sethi
+ instruction
+
+ `R'
+ Floating-point constant whose integral representation can be
+ moved into an integer register using a single mov instruction
+
+ `S'
+ Floating-point constant whose integral representation can be
+ moved into an integer register using a high/lo_sum
+ instruction sequence
+
+ `T'
+ Memory address aligned to an 8-byte boundary
+
+ `U'
+ Even register
+
+ `W'
+ Memory address for `e' constraint registers.
+
+
+_TMS320C3x/C4x--`c4x.h'_
+
+ `a'
+ Auxiliary (address) register (ar0-ar7)
+
+ `b'
+ Stack pointer register (sp)
+
+ `c'
+ Standard (32-bit) precision integer register
+
+ `f'
+ Extended (40-bit) precision register (r0-r11)
+
+ `k'
+ Block count register (bk)
+
+ `q'
+ Extended (40-bit) precision low register (r0-r7)
+
+ `t'
+ Extended (40-bit) precision register (r0-r1)
+
+ `u'
+ Extended (40-bit) precision register (r2-r3)
+
+ `v'
+ Repeat count register (rc)
+
+ `x'
+ Index register (ir0-ir1)
+
+ `y'
+ Status (condition code) register (st)
+
+ `z'
+ Data page register (dp)
+
+ `G'
+ Floating-point zero
+
+ `H'
+ Immediate 16-bit floating-point constant
+
+ `I'
+ Signed 16-bit constant
+
+ `J'
+ Signed 8-bit constant
+
+ `K'
+ Signed 5-bit constant
+
+ `L'
+ Unsigned 16-bit constant
+
+ `M'
+ Unsigned 8-bit constant
+
+ `N'
+ Ones complement of unsigned 16-bit constant
+
+ `O'
+ High 16-bit constant (32-bit constant with 16 LSBs zero)
+
+ `Q'
+ Indirect memory reference with signed 8-bit or index register
+ displacement
+
+ `R'
+ Indirect memory reference with unsigned 5-bit displacement
+
+ `S'
+ Indirect memory reference with 1 bit or index register
+ displacement
+
+ `T'
+ Direct memory reference
+
+ `U'
+ Symbolic address
+
+
+_S/390 and zSeries--`s390.h'_
+
+ `a'
+ Address register (general purpose register except r0)
+
+ `d'
+ Data register (arbitrary general purpose register)
+
+ `f'
+ Floating-point register
+
+ `I'
+ Unsigned 8-bit constant (0-255)
+
+ `J'
+ Unsigned 12-bit constant (0-4095)
+
+ `K'
+ Signed 16-bit constant (-32768-32767)
+
+ `L'
+ Unsigned 16-bit constant (0-65535)
+
+ `Q'
+ Memory reference without index register
+
+ `S'
+ Symbolic constant suitable for use with the `larl' instruction
+
+
+_Xstormy16--`stormy16.h'_
+
+ `a'
+ Register r0.
+
+ `b'
+ Register r1.
+
+ `c'
+ Register r2.
+
+ `d'
+ Register r8.
+
+ `e'
+ Registers r0 through r7.
+
+ `t'
+ Registers r0 and r1.
+
+ `y'
+ The carry register.
+
+ `z'
+ Registers r8 and r9.
+
+ `I'
+ A constant between 0 and 3 inclusive.
+
+ `J'
+ A constant that has exactly one bit set.
+
+ `K'
+ A constant that has exactly one bit clear.
+
+ `L'
+ A constant between 0 and 255 inclusive.
+
+ `M'
+ A constant between -255 and 0 inclusive.
+
+ `N'
+ A constant between -3 and 0 inclusive.
+
+ `O'
+ A constant between 1 and 4 inclusive.
+
+ `P'
+ A constant between -4 and -1 inclusive.
+
+ `Q'
+ A memory reference that is a stack push.
+
+ `R'
+ A memory reference that is a stack pop.
+
+ `S'
+ A memory reference that refers to an constant address of
+ known value.
+
+ `T'
+ The register indicated by Rx (not implemented yet).
+
+ `U'
+ A constant that is not between 2 and 15 inclusive.
+
+
+_Xtensa--`xtensa.h'_
+
+ `a'
+ General-purpose 32-bit register
+
+ `b'
+ One-bit boolean register
+
+ `A'
+ MAC16 40-bit accumulator register
+
+ `I'
+ Signed 12-bit integer constant, for use in MOVI instructions
+
+ `J'
+ Signed 8-bit integer constant, for use in ADDI instructions
+
+ `K'
+ Integer constant valid for BccI instructions
+
+ `L'
+ Unsigned constant valid for BccUI instructions
+
+
+
+\1f
+File: gcc.info, Node: Asm Labels, Next: Explicit Reg Vars, Prev: Constraints, Up: C Extensions
+
+5.37 Controlling Names Used in Assembler Code
+=============================================
+
+You can specify the name to be used in the assembler code for a C
+function or variable by writing the `asm' (or `__asm__') keyword after
+the declarator as follows:
+
+ int foo asm ("myfoo") = 2;
+
+This specifies that the name to be used for the variable `foo' in the
+assembler code should be `myfoo' rather than the usual `_foo'.
+
+ On systems where an underscore is normally prepended to the name of
+a C function or variable, this feature allows you to define names for
+the linker that do not start with an underscore.
+
+ It does not make sense to use this feature with a non-static local
+variable since such variables do not have assembler names. If you are
+trying to put the variable in a particular register, see *note Explicit
+Reg Vars::. GCC presently accepts such code with a warning, but will
+probably be changed to issue an error, rather than a warning, in the
+future.
+
+ You cannot use `asm' in this way in a function _definition_; but you
+can get the same effect by writing a declaration for the function
+before its definition and putting `asm' there, like this:
+
+ extern func () asm ("FUNC");
+
+ func (x, y)
+ int x, y;
+ ...
+
+ It is up to you to make sure that the assembler names you choose do
+not conflict with any other assembler symbols. Also, you must not use a
+register name; that would produce completely invalid assembler code.
+GCC does not as yet have the ability to store static variables in
+registers. Perhaps that will be added.
+
+\1f
+File: gcc.info, Node: Explicit Reg Vars, Next: Alternate Keywords, Prev: Asm Labels, Up: C Extensions
+
+5.38 Variables in Specified Registers
+=====================================
+
+GNU C allows you to put a few global variables into specified hardware
+registers. You can also specify the register in which an ordinary
+register variable should be allocated.
+
+ * Global register variables reserve registers throughout the program.
+ This may be useful in programs such as programming language
+ interpreters which have a couple of global variables that are
+ accessed very often.
+
+ * Local register variables in specific registers do not reserve the
+ registers. The compiler's data flow analysis is capable of
+ determining where the specified registers contain live values, and
+ where they are available for other uses. Stores into local
+ register variables may be deleted when they appear to be dead
+ according to dataflow analysis. References to local register
+ variables may be deleted or moved or simplified.
+
+ These local variables are sometimes convenient for use with the
+ extended `asm' feature (*note Extended Asm::), if you want to
+ write one output of the assembler instruction directly into a
+ particular register. (This will work provided the register you
+ specify fits the constraints specified for that operand in the
+ `asm'.)
+
+* Menu:
+
+* Global Reg Vars::
+* Local Reg Vars::
+
+\1f
+File: gcc.info, Node: Global Reg Vars, Next: Local Reg Vars, Up: Explicit Reg Vars
+
+5.38.1 Defining Global Register Variables
+-----------------------------------------
+
+You can define a global register variable in GNU C like this:
+
+ register int *foo asm ("a5");
+
+Here `a5' is the name of the register which should be used. Choose a
+register which is normally saved and restored by function calls on your
+machine, so that library routines will not clobber it.
+
+ Naturally the register name is cpu-dependent, so you would need to
+conditionalize your program according to cpu type. The register `a5'
+would be a good choice on a 68000 for a variable of pointer type. On
+machines with register windows, be sure to choose a "global" register
+that is not affected magically by the function call mechanism.
+
+ In addition, operating systems on one type of cpu may differ in how
+they name the registers; then you would need additional conditionals.
+For example, some 68000 operating systems call this register `%a5'.
+
+ Eventually there may be a way of asking the compiler to choose a
+register automatically, but first we need to figure out how it should
+choose and how to enable you to guide the choice. No solution is
+evident.
+
+ Defining a global register variable in a certain register reserves
+that register entirely for this use, at least within the current
+compilation. The register will not be allocated for any other purpose
+in the functions in the current compilation. The register will not be
+saved and restored by these functions. Stores into this register are
+never deleted even if they would appear to be dead, but references may
+be deleted or moved or simplified.
+
+ It is not safe to access the global register variables from signal
+handlers, or from more than one thread of control, because the system
+library routines may temporarily use the register for other things
+(unless you recompile them specially for the task at hand).
+
+ It is not safe for one function that uses a global register variable
+to call another such function `foo' by way of a third function `lose'
+that was compiled without knowledge of this variable (i.e. in a
+different source file in which the variable wasn't declared). This is
+because `lose' might save the register and put some other value there.
+For example, you can't expect a global register variable to be
+available in the comparison-function that you pass to `qsort', since
+`qsort' might have put something else in that register. (If you are
+prepared to recompile `qsort' with the same global register variable,
+you can solve this problem.)
+
+ If you want to recompile `qsort' or other source files which do not
+actually use your global register variable, so that they will not use
+that register for any other purpose, then it suffices to specify the
+compiler option `-ffixed-REG'. You need not actually add a global
+register declaration to their source code.
+
+ A function which can alter the value of a global register variable
+cannot safely be called from a function compiled without this variable,
+because it could clobber the value the caller expects to find there on
+return. Therefore, the function which is the entry point into the part
+of the program that uses the global register variable must explicitly
+save and restore the value which belongs to its caller.
+
+ On most machines, `longjmp' will restore to each global register
+variable the value it had at the time of the `setjmp'. On some
+machines, however, `longjmp' will not change the value of global
+register variables. To be portable, the function that called `setjmp'
+should make other arrangements to save the values of the global register
+variables, and to restore them in a `longjmp'. This way, the same
+thing will happen regardless of what `longjmp' does.
+
+ All global register variable declarations must precede all function
+definitions. If such a declaration could appear after function
+definitions, the declaration would be too late to prevent the register
+from being used for other purposes in the preceding functions.
+
+ Global register variables may not have initial values, because an
+executable file has no means to supply initial contents for a register.
+
+ On the Sparc, there are reports that g3 ... g7 are suitable
+registers, but certain library functions, such as `getwd', as well as
+the subroutines for division and remainder, modify g3 and g4. g1 and
+g2 are local temporaries.
+
+ On the 68000, a2 ... a5 should be suitable, as should d2 ... d7. Of
+course, it will not do to use more than a few of those.
+
+\1f
+File: gcc.info, Node: Local Reg Vars, Prev: Global Reg Vars, Up: Explicit Reg Vars
+
+5.38.2 Specifying Registers for Local Variables
+-----------------------------------------------
+
+You can define a local register variable with a specified register like
+this:
+
+ register int *foo asm ("a5");
+
+Here `a5' is the name of the register which should be used. Note that
+this is the same syntax used for defining global register variables,
+but for a local variable it would appear within a function.
+
+ Naturally the register name is cpu-dependent, but this is not a
+problem, since specific registers are most often useful with explicit
+assembler instructions (*note Extended Asm::). Both of these things
+generally require that you conditionalize your program according to cpu
+type.
+
+ In addition, operating systems on one type of cpu may differ in how
+they name the registers; then you would need additional conditionals.
+For example, some 68000 operating systems call this register `%a5'.
+
+ Defining such a register variable does not reserve the register; it
+remains available for other uses in places where flow control determines
+the variable's value is not live. However, these registers are made
+unavailable for use in the reload pass; excessive use of this feature
+leaves the compiler too few available registers to compile certain
+functions.
+
+ This option does not guarantee that GCC will generate code that has
+this variable in the register you specify at all times. You may not
+code an explicit reference to this register in an `asm' statement and
+assume it will always refer to this variable.
+
+ Stores into local register variables may be deleted when they appear
+to be dead according to dataflow analysis. References to local
+register variables may be deleted or moved or simplified.
+
+\1f
+File: gcc.info, Node: Alternate Keywords, Next: Incomplete Enums, Prev: Explicit Reg Vars, Up: C Extensions
+
+5.39 Alternate Keywords
+=======================
+
+The option `-traditional' disables certain keywords; `-ansi' and the
+various `-std' options disable certain others. This causes trouble
+when you want to use GNU C extensions, or ISO C features, in a
+general-purpose header file that should be usable by all programs,
+including ISO C programs and traditional ones. The keywords `asm',
+`typeof' and `inline' cannot be used since they won't work in a program
+compiled with `-ansi' (although `inline' can be used in a program
+compiled with `-std=c99'), while the keywords `const', `volatile',
+`signed', `typeof' and `inline' won't work in a program compiled with
+`-traditional'. The ISO C99 keyword `restrict' is only available when
+`-std=gnu99' (which will eventually be the default) or `-std=c99' (or
+the equivalent `-std=iso9899:1999') is used.
+
+ The way to solve these problems is to put `__' at the beginning and
+end of each problematical keyword. For example, use `__asm__' instead
+of `asm', `__const__' instead of `const', and `__inline__' instead of
+`inline'.
+
+ Other C compilers won't accept these alternative keywords; if you
+want to compile with another compiler, you can define the alternate
+keywords as macros to replace them with the customary keywords. It
+looks like this:
+
+ #ifndef __GNUC__
+ #define __asm__ asm
+ #endif
+
+ `-pedantic' and other options cause warnings for many GNU C
+extensions. You can prevent such warnings within one expression by
+writing `__extension__' before the expression. `__extension__' has no
+effect aside from this.
+
+\1f
+File: gcc.info, Node: Incomplete Enums, Next: Function Names, Prev: Alternate Keywords, Up: C Extensions
+
+5.40 Incomplete `enum' Types
+============================
+
+You can define an `enum' tag without specifying its possible values.
+This results in an incomplete type, much like what you get if you write
+`struct foo' without describing the elements. A later declaration
+which does specify the possible values completes the type.
+
+ You can't allocate variables or storage using the type while it is
+incomplete. However, you can work with pointers to that type.
+
+ This extension may not be very useful, but it makes the handling of
+`enum' more consistent with the way `struct' and `union' are handled.
+
+ This extension is not supported by GNU C++.
+
+\1f
+File: gcc.info, Node: Function Names, Next: Return Address, Prev: Incomplete Enums, Up: C Extensions
+
+5.41 Function Names as Strings
+==============================
+
+GCC predefines two magic identifiers to hold the name of the current
+function. The identifier `__FUNCTION__' holds the name of the function
+as it appears in the source. The identifier `__PRETTY_FUNCTION__'
+holds the name of the function pretty printed in a language specific
+fashion.
+
+ These names are always the same in a C function, but in a C++
+function they may be different. For example, this program:
+
+ extern "C" {
+ extern int printf (char *, ...);
+ }
+
+ class a {
+ public:
+ sub (int i)
+ {
+ printf ("__FUNCTION__ = %s\n", __FUNCTION__);
+ printf ("__PRETTY_FUNCTION__ = %s\n", __PRETTY_FUNCTION__);
+ }
+ };
+
+ int
+ main (void)
+ {
+ a ax;
+ ax.sub (0);
+ return 0;
+ }
+
+gives this output:
+
+ __FUNCTION__ = sub
+ __PRETTY_FUNCTION__ = int a::sub (int)
+
+ The compiler automagically replaces the identifiers with a string
+literal containing the appropriate name. Thus, they are neither
+preprocessor macros, like `__FILE__' and `__LINE__', nor variables.
+This means that they catenate with other string literals, and that they
+can be used to initialize char arrays. For example
+
+ char here[] = "Function " __FUNCTION__ " in " __FILE__;
+
+ On the other hand, `#ifdef __FUNCTION__' does not have any special
+meaning inside a function, since the preprocessor does not do anything
+special with the identifier `__FUNCTION__'.
+
+ Note that these semantics are deprecated, and that GCC 3.2 will
+handle `__FUNCTION__' and `__PRETTY_FUNCTION__' the same way as
+`__func__'. `__func__' is defined by the ISO standard C99:
+
+ The identifier `__func__' is implicitly declared by the translator
+ as if, immediately following the opening brace of each function
+ definition, the declaration
+ static const char __func__[] = "function-name";
+
+ appeared, where function-name is the name of the lexically-enclosing
+ function. This name is the unadorned name of the function.
+
+ By this definition, `__func__' is a variable, not a string literal.
+In particular, `__func__' does not catenate with other string literals.
+
+ In `C++', `__FUNCTION__' and `__PRETTY_FUNCTION__' are variables,
+declared in the same way as `__func__'.
+
+\1f
+File: gcc.info, Node: Return Address, Next: Vector Extensions, Prev: Function Names, Up: C Extensions
+
+5.42 Getting the Return or Frame Address of a Function
+======================================================
+
+These functions may be used to get information about the callers of a
+function.
+
+ -- Built-in Function: void * __builtin_return_address (unsigned int
+ LEVEL)
+ This function returns the return address of the current function,
+ or of one of its callers. The LEVEL argument is number of frames
+ to scan up the call stack. A value of `0' yields the return
+ address of the current function, a value of `1' yields the return
+ address of the caller of the current function, and so forth.
+
+ The LEVEL argument must be a constant integer.
+
+ On some machines it may be impossible to determine the return
+ address of any function other than the current one; in such cases,
+ or when the top of the stack has been reached, this function will
+ return `0' or a random value. In addition,
+ `__builtin_frame_address' may be used to determine if the top of
+ the stack has been reached.
+
+ This function should only be used with a nonzero argument for
+ debugging purposes.
+
+ -- Built-in Function: void * __builtin_frame_address (unsigned int
+ LEVEL)
+ This function is similar to `__builtin_return_address', but it
+ returns the address of the function frame rather than the return
+ address of the function. Calling `__builtin_frame_address' with a
+ value of `0' yields the frame address of the current function, a
+ value of `1' yields the frame address of the caller of the current
+ function, and so forth.
+
+ The frame is the area on the stack which holds local variables and
+ saved registers. The frame address is normally the address of the
+ first word pushed on to the stack by the function. However, the
+ exact definition depends upon the processor and the calling
+ convention. If the processor has a dedicated frame pointer
+ register, and the function has a frame, then
+ `__builtin_frame_address' will return the value of the frame
+ pointer register.
+
+ On some machines it may be impossible to determine the frame
+ address of any function other than the current one; in such cases,
+ or when the top of the stack has been reached, this function will
+ return `0' if the first frame pointer is properly initialized by
+ the startup code.
+
+ This function should only be used with a nonzero argument for
+ debugging purposes.
+
+\1f
+File: gcc.info, Node: Vector Extensions, Next: Other Builtins, Prev: Return Address, Up: C Extensions
+
+5.43 Using vector instructions through built-in functions
+=========================================================
+
+On some targets, the instruction set contains SIMD vector instructions
+that operate on multiple values contained in one large register at the
+same time. For example, on the i386 the MMX, 3Dnow! and SSE extensions
+can be used this way.
+
+ The first step in using these extensions is to provide the necessary
+data types. This should be done using an appropriate `typedef':
+
+ typedef int v4si __attribute__ ((mode(V4SI)));
+
+ The base type `int' is effectively ignored by the compiler, the
+actual properties of the new type `v4si' are defined by the
+`__attribute__'. It defines the machine mode to be used; for vector
+types these have the form `VNB'; N should be the number of elements in
+the vector, and B should be the base mode of the individual elements.
+The following can be used as base modes:
+
+`QI'
+ An integer that is as wide as the smallest addressable unit,
+ usually 8 bits.
+
+`HI'
+ An integer, twice as wide as a QI mode integer, usually 16 bits.
+
+`SI'
+ An integer, four times as wide as a QI mode integer, usually 32
+ bits.
+
+`DI'
+ An integer, eight times as wide as a QI mode integer, usually 64
+ bits.
+
+`SF'
+ A floating point value, as wide as a SI mode integer, usually 32
+ bits.
+
+`DF'
+ A floating point value, as wide as a DI mode integer, usually 64
+ bits.
+
+ Not all base types or combinations are always valid; which modes can
+be used is determined by the target machine. For example, if
+targetting the i386 MMX extensions, only `V8QI', `V4HI' and `V2SI' are
+allowed modes.
+
+ There are no `V1xx' vector modes - they would be identical to the
+corresponding base mode.
+
+ There is no distinction between signed and unsigned vector modes.
+This distinction is made by the operations that perform on the vectors,
+not by the data type.
+
+ The types defined in this manner are somewhat special, they cannot be
+used with most normal C operations (i.e., a vector addition can _not_
+be represented by a normal addition of two vector type variables). You
+can declare only variables and use them in function calls and returns,
+as well as in assignments and some casts. It is possible to cast from
+one vector type to another, provided they are of the same size (in
+fact, you can also cast vectors to and from other datatypes of the same
+size).
+
+ A port that supports vector operations provides a set of built-in
+functions that can be used to operate on vectors. For example, a
+function to add two vectors and multiply the result by a third could
+look like this:
+
+ v4si f (v4si a, v4si b, v4si c)
+ {
+ v4si tmp = __builtin_addv4si (a, b);
+ return __builtin_mulv4si (tmp, c);
+ }
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Bug Reporting, Next: gccbug, Prev: Bug Lists, Up: Bugs
-
-How to Report Bugs
-==================
-
- The fundamental principle of reporting bugs usefully is this:
-*report all the facts*. If you are not sure whether to state a fact or
-leave it out, state it!
-
- Often people omit facts because they think they know what causes the
-problem and they conclude that some details don't matter. Thus, you
-might assume that the name of the variable you use in an example does
-not matter. Well, probably it doesn't, but one cannot be sure.
-Perhaps the bug is a stray memory reference which happens to fetch from
-the location where that name is stored in memory; perhaps, if the name
-were different, the contents of that location would fool the compiler
-into doing the right thing despite the bug. Play it safe and give a
-specific, complete example. That is the easiest thing for you to do,
-and the most helpful.
-
- Keep in mind that the purpose of a bug report is to enable someone to
-fix the bug if it is not known. It isn't very important what happens if
-the bug is already known. Therefore, always write your bug reports on
-the assumption that the bug is not known.
-
- Sometimes people give a few sketchy facts and ask, "Does this ring a
-bell?" This cannot help us fix a bug, so it is basically useless. We
-respond by asking for enough details to enable us to investigate. You
-might as well expedite matters by sending them to begin with.
-
- Try to make your bug report self-contained. If we have to ask you
-for more information, it is best if you include all the previous
-information in your response, as well as the information that was
-missing.
-
- Please report each bug in a separate message. This makes it easier
-for us to track which bugs have been fixed and to forward your bugs
-reports to the appropriate maintainer.
-
- To enable someone to investigate the bug, you should include all
-these things:
-
- * The version of GCC. You can get this by running it with the `-v'
- option.
-
- Without this, we won't know whether there is any point in looking
- for the bug in the current version of GCC.
-
- * A complete input file that will reproduce the bug. If the bug is
- in the C preprocessor, send a source file and any header files
- that it requires. If the bug is in the compiler proper (`cc1'),
- send the preprocessor output generated by adding `-save-temps' to
- the compilation command (*note Debugging Options::). When you do
- this, use the same `-I', `-D' or `-U' options that you used in
- actual compilation. Then send the INPUT.i or INPUT.ii files
- generated.
-
- A single statement is not enough of an example. In order to
- compile it, it must be embedded in a complete file of compiler
- input; and the bug might depend on the details of how this is done.
-
- Without a real example one can compile, all anyone can do about
- your bug report is wish you luck. It would be futile to try to
- guess how to provoke the bug. For example, bugs in register
- allocation and reloading frequently depend on every little detail
- of the function they happen in.
-
- Even if the input file that fails comes from a GNU program, you
- should still send the complete test case. Don't ask the GCC
- maintainers to do the extra work of obtaining the program in
- question--they are all overworked as it is. Also, the problem may
- depend on what is in the header files on your system; it is
- unreliable for the GCC maintainers to try the problem with the
- header files available to them. By sending CPP output, you can
- eliminate this source of uncertainty and save us a certain
- percentage of wild goose chases.
-
- * The command arguments you gave GCC to compile that example and
- observe the bug. For example, did you use `-O'? To guarantee you
- won't omit something important, list all the options.
-
- If we were to try to guess the arguments, we would probably guess
- wrong and then we would not encounter the bug.
-
- * The type of machine you are using, and the operating system name
- and version number.
-
- * The operands you gave to the `configure' command when you installed
- the compiler.
-
- * A complete list of any modifications you have made to the compiler
- source. (We don't promise to investigate the bug unless it
- happens in an unmodified compiler. But if you've made
- modifications and don't tell us, then you are sending us on a wild
- goose chase.)
-
- Be precise about these changes. A description in English is not
- enough--send a context diff for them.
-
- Adding files of your own (such as a machine description for a
- machine we don't support) is a modification of the compiler source.
-
- * Details of any other deviations from the standard procedure for
- installing GCC.
-
- * A description of what behavior you observe that you believe is
- incorrect. For example, "The compiler gets a fatal signal," or,
- "The assembler instruction at line 208 in the output is incorrect."
-
- Of course, if the bug is that the compiler gets a fatal signal,
- then one can't miss it. But if the bug is incorrect output, the
- maintainer might not notice unless it is glaringly wrong. None of
- us has time to study all the assembler code from a 50-line C
- program just on the chance that one instruction might be wrong.
- We need _you_ to do this part!
-
- Even if the problem you experience is a fatal signal, you should
- still say so explicitly. Suppose something strange is going on,
- such as, your copy of the compiler is out of synch, or you have
- encountered a bug in the C library on your system. (This has
- happened!) Your copy might crash and the copy here would not. If
- you said to expect a crash, then when the compiler here fails to
- crash, we would know that the bug was not happening. If you don't
- say to expect a crash, then we would not know whether the bug was
- happening. We would not be able to draw any conclusion from our
- observations.
-
- If the problem is a diagnostic when compiling GCC with some other
- compiler, say whether it is a warning or an error.
-
- Often the observed symptom is incorrect output when your program
- is run. Sad to say, this is not enough information unless the
- program is short and simple. None of us has time to study a large
- program to figure out how it would work if compiled correctly,
- much less which line of it was compiled wrong. So you will have
- to do that. Tell us which source line it is, and what incorrect
- result happens when that line is executed. A person who
- understands the program can find this as easily as finding a bug
- in the program itself.
-
- * If you send examples of assembler code output from GCC, please use
- `-g' when you make them. The debugging information includes
- source line numbers which are essential for correlating the output
- with the input.
-
- * If you wish to mention something in the GCC source, refer to it by
- context, not by line number.
-
- The line numbers in the development sources don't match those in
- your sources. Your line numbers would convey no useful
- information to the maintainers.
-
- * Additional information from a debugger might enable someone to
- find a problem on a machine which he does not have available.
- However, you need to think when you collect this information if
- you want it to have any chance of being useful.
-
- For example, many people send just a backtrace, but that is never
- useful by itself. A simple backtrace with arguments conveys little
- about GCC because the compiler is largely data-driven; the same
- functions are called over and over for different RTL insns, doing
- different things depending on the details of the insn.
-
- Most of the arguments listed in the backtrace are useless because
- they are pointers to RTL list structure. The numeric values of the
- pointers, which the debugger prints in the backtrace, have no
- significance whatever; all that matters is the contents of the
- objects they point to (and most of the contents are other such
- pointers).
-
- In addition, most compiler passes consist of one or more loops that
- scan the RTL insn sequence. The most vital piece of information
- about such a loop--which insn it has reached--is usually in a
- local variable, not in an argument.
-
- What you need to provide in addition to a backtrace are the values
- of the local variables for several stack frames up. When a local
- variable or an argument is an RTX, first print its value and then
- use the GDB command `pr' to print the RTL expression that it points
- to. (If GDB doesn't run on your machine, use your debugger to call
- the function `debug_rtx' with the RTX as an argument.) In
- general, whenever a variable is a pointer, its value is no use
- without the data it points to.
-
- Here are some things that are not necessary:
-
- * A description of the envelope of the bug.
-
- Often people who encounter a bug spend a lot of time investigating
- which changes to the input file will make the bug go away and which
- changes will not affect it.
-
- This is often time consuming and not very useful, because the way
- we will find the bug is by running a single example under the
- debugger with breakpoints, not by pure deduction from a series of
- examples. You might as well save your time for something else.
-
- Of course, if you can find a simpler example to report _instead_ of
- the original one, that is a convenience. Errors in the output
- will be easier to spot, running under the debugger will take less
- time, etc. Most GCC bugs involve just one function, so the most
- straightforward way to simplify an example is to delete all the
- function definitions except the one where the bug occurs. Those
- earlier in the file may be replaced by external declarations if
- the crucial function depends on them. (Exception: inline
- functions may affect compilation of functions defined later in the
- file.)
-
- However, simplification is not vital; if you don't want to do this,
- report the bug anyway and send the entire test case you used.
-
- * In particular, some people insert conditionals `#ifdef BUG' around
- a statement which, if removed, makes the bug not happen. These
- are just clutter; we won't pay any attention to them anyway.
- Besides, you should send us cpp output, and that can't have
- conditionals.
-
- * A patch for the bug.
-
- A patch for the bug is useful if it is a good one. But don't omit
- the necessary information, such as the test case, on the
- assumption that a patch is all we need. We might see problems
- with your patch and decide to fix the problem another way, or we
- might not understand it at all.
-
- Sometimes with a program as complicated as GCC it is very hard to
- construct an example that will make the program follow a certain
- path through the code. If you don't send the example, we won't be
- able to construct one, so we won't be able to verify that the bug
- is fixed.
-
- And if we can't understand what bug you are trying to fix, or why
- your patch should be an improvement, we won't install it. A test
- case will help us to understand.
-
- See `http://gcc.gnu.org/contribute.html' for guidelines on how to
- make it easy for us to understand and install your patches.
-
- * A guess about what the bug is or what it depends on.
-
- Such guesses are usually wrong. Even I can't guess right about
- such things without first using the debugger to find the facts.
-
- * A core dump file.
-
- We have no way of examining a core dump for your type of machine
- unless we have an identical system--and if we do have one, we
- should be able to reproduce the crash ourselves.
-
-\1f
-File: gcc.info, Node: gccbug, Prev: Bug Reporting, Up: Bugs
-
-The gccbug script
-=================
-
- To simplify creation of bug reports, and to allow better tracking of
-reports, we use the GNATS bug tracking system. Part of that system is
-the `gccbug' script. This is a Unix shell script, so you need a shell
-to run it. It is normally installed in the same directory where `gcc'
-is installed.
-
- The gccbug script is derived from send-pr, *note Creating new
-Problem Reports: (send-pr)using send-pr.. When invoked, it starts a
-text editor so you can fill out the various fields of the report. When
-the you quit the editor, the report is automatically send to the bug
-reporting address.
-
- A number of fields in this bug report form are specific to GCC, and
-are explained at `http://gcc.gnu.org/gnats.html'.
-
-\1f
-File: gcc.info, Node: Service, Next: Contributing, Prev: Bugs, Up: Top
-
-How To Get Help with GCC
-************************
-
- If you need help installing, using or changing GCC, there are two
-ways to find it:
-
- * Send a message to a suitable network mailing list. First try
- <gcc-help@gcc.gnu.org> (for help installing or using GCC), and if
- that brings no response, try <gcc@gcc.gnu.org>. For help changing
- GCC, ask <gcc@gcc.gnu.org>. If you think you have found a bug in
- GCC, please report it following the instructions at *note Bug
- Reporting::.
-
- * Look in the service directory for someone who might help you for a
- fee. The service directory is found at
- `http://www.gnu.org/prep/service.html'.
-
-\1f
-File: gcc.info, Node: Contributing, Next: VMS, Prev: Service, Up: Top
-
-Contributing to GCC Development
-*******************************
-
- If you would like to help pretest GCC releases to assure they work
-well, our current development sources are available by CVS (see
-`http://gcc.gnu.org/cvs.html'). Source and binary snapshots are also
-available for FTP; see `http://gcc.gnu.org/snapshots.html'.
-
- If you would like to work on improvements to GCC, please read the
-advice at these URLs:
-
- `http://gcc.gnu.org/contribute.html'
- `http://gcc.gnu.org/contributewhy.html'
-
-for information on how to make useful contributions and avoid
-duplication of effort. Suggested projects are listed at
-`http://gcc.gnu.org/projects/'.
-
-\1f
-File: gcc.info, Node: VMS, Next: Funding, Prev: Contributing, Up: Top
-
-Using GCC on VMS
-****************
-
- Here is how to use GCC on VMS.
-
-* Menu:
-
-* Include Files and VMS:: Where the preprocessor looks for the include files.
-* Global Declarations:: How to do globaldef, globalref and globalvalue with
- GCC.
-* VMS Misc:: Misc information.
-
-\1f
-File: gcc.info, Node: Include Files and VMS, Next: Global Declarations, Up: VMS
-
-Include Files and VMS
-=====================
-
- Due to the differences between the filesystems of Unix and VMS, GCC
-attempts to translate file names in `#include' into names that VMS will
-understand. The basic strategy is to prepend a prefix to the
-specification of the include file, convert the whole filename to a VMS
-filename, and then try to open the file. GCC tries various prefixes
-one by one until one of them succeeds:
-
- 1. The first prefix is the `GNU_CC_INCLUDE:' logical name: this is
- where GNU C header files are traditionally stored. If you wish to
- store header files in non-standard locations, then you can assign
- the logical `GNU_CC_INCLUDE' to be a search list, where each
- element of the list is suitable for use with a rooted logical.
-
- 2. The next prefix tried is `SYS$SYSROOT:[SYSLIB.]'. This is where
- VAX-C header files are traditionally stored.
-
- 3. If the include file specification by itself is a valid VMS
- filename, the preprocessor then uses this name with no prefix in
- an attempt to open the include file.
-
- 4. If the file specification is not a valid VMS filename (i.e. does
- not contain a device or a directory specifier, and contains a `/'
- character), the preprocessor tries to convert it from Unix syntax
- to VMS syntax.
-
- Conversion works like this: the first directory name becomes a
- device, and the rest of the directories are converted into
- VMS-format directory names. For example, the name `X11/foobar.h'
- is translated to `X11:[000000]foobar.h' or `X11:foobar.h',
- whichever one can be opened. This strategy allows you to assign a
- logical name to point to the actual location of the header files.
-
- 5. If none of these strategies succeeds, the `#include' fails.
-
- Include directives of the form:
-
- #include foobar
-
-are a common source of incompatibility between VAX-C and GCC. VAX-C
-treats this much like a standard `#include <foobar.h>' directive. That
-is incompatible with the ISO C behavior implemented by GCC: to expand
-the name `foobar' as a macro. Macro expansion should eventually yield
-one of the two standard formats for `#include':
-
- #include "FILE"
- #include <FILE>
-
- If you have this problem, the best solution is to modify the source
-to convert the `#include' directives to one of the two standard forms.
-That will work with either compiler. If you want a quick and dirty fix,
-define the file names as macros with the proper expansion, like this:
-
- #define stdio <stdio.h>
-
-This will work, as long as the name doesn't conflict with anything else
-in the program.
-
- Another source of incompatibility is that VAX-C assumes that:
-
- #include "foobar"
-
-is actually asking for the file `foobar.h'. GCC does not make this
-assumption, and instead takes what you ask for literally; it tries to
-read the file `foobar'. The best way to avoid this problem is to
-always specify the desired file extension in your include directives.
-
- GCC for VMS is distributed with a set of include files that is
-sufficient to compile most general purpose programs. Even though the
-GCC distribution does not contain header files to define constants and
-structures for some VMS system-specific functions, there is no reason
-why you cannot use GCC with any of these functions. You first may have
-to generate or create header files, either by using the public domain
-utility `UNSDL' (which can be found on a DECUS tape), or by extracting
-the relevant modules from one of the system macro libraries, and using
-an editor to construct a C header file.
-
- A `#include' file name cannot contain a DECNET node name. The
-preprocessor reports an I/O error if you attempt to use a node name,
-whether explicitly, or implicitly via a logical name.
-
-\1f
-File: gcc.info, Node: Global Declarations, Next: VMS Misc, Prev: Include Files and VMS, Up: VMS
-
-Global Declarations and VMS
-===========================
-
- GCC does not provide the `globalref', `globaldef' and `globalvalue'
-keywords of VAX-C. You can get the same effect with an obscure feature
-of GAS, the GNU assembler. (This requires GAS version 1.39 or later.)
-The following macros allow you to use this feature in a fairly natural
-way:
-
- #ifdef __GNUC__
- #define GLOBALREF(TYPE,NAME) \
- TYPE NAME \
- asm ("_$$PsectAttributes_GLOBALSYMBOL$$" #NAME)
- #define GLOBALDEF(TYPE,NAME,VALUE) \
- TYPE NAME \
- asm ("_$$PsectAttributes_GLOBALSYMBOL$$" #NAME) \
- = VALUE
- #define GLOBALVALUEREF(TYPE,NAME) \
- const TYPE NAME[1] \
- asm ("_$$PsectAttributes_GLOBALVALUE$$" #NAME)
- #define GLOBALVALUEDEF(TYPE,NAME,VALUE) \
- const TYPE NAME[1] \
- asm ("_$$PsectAttributes_GLOBALVALUE$$" #NAME) \
- = {VALUE}
- #else
- #define GLOBALREF(TYPE,NAME) \
- globalref TYPE NAME
- #define GLOBALDEF(TYPE,NAME,VALUE) \
- globaldef TYPE NAME = VALUE
- #define GLOBALVALUEDEF(TYPE,NAME,VALUE) \
- globalvalue TYPE NAME = VALUE
- #define GLOBALVALUEREF(TYPE,NAME) \
- globalvalue TYPE NAME
- #endif
-
-(The `_$$PsectAttributes_GLOBALSYMBOL' prefix at the start of the name
-is removed by the assembler, after it has modified the attributes of
-the symbol). These macros are provided in the VMS binaries
-distribution in a header file `GNU_HACKS.H'. An example of the usage
-is:
-
- GLOBALREF (int, ijk);
- GLOBALDEF (int, jkl, 0);
-
- The macros `GLOBALREF' and `GLOBALDEF' cannot be used
-straightforwardly for arrays, since there is no way to insert the array
-dimension into the declaration at the right place. However, you can
-declare an array with these macros if you first define a typedef for the
-array type, like this:
-
- typedef int intvector[10];
- GLOBALREF (intvector, foo);
-
- Array and structure initializers will also break the macros; you can
-define the initializer to be a macro of its own, or you can expand the
-`GLOBALDEF' macro by hand. You may find a case where you wish to use
-the `GLOBALDEF' macro with a large array, but you are not interested in
-explicitly initializing each element of the array. In such cases you
-can use an initializer like: `{0,}', which will initialize the entire
-array to `0'.
-
- A shortcoming of this implementation is that a variable declared with
-`GLOBALVALUEREF' or `GLOBALVALUEDEF' is always an array. For example,
-the declaration:
-
- GLOBALVALUEREF(int, ijk);
-
-declares the variable `ijk' as an array of type `int [1]'. This is
-done because a globalvalue is actually a constant; its "value" is what
-the linker would normally consider an address. That is not how an
-integer value works in C, but it is how an array works. So treating
-the symbol as an array name gives consistent results--with the
-exception that the value seems to have the wrong type. *Don't try to
-access an element of the array.* It doesn't have any elements. The
-array "address" may not be the address of actual storage.
-
- The fact that the symbol is an array may lead to warnings where the
-variable is used. Insert type casts to avoid the warnings. Here is an
-example; it takes advantage of the ISO C feature allowing macros that
-expand to use the same name as the macro itself.
-
- GLOBALVALUEREF (int, ss$_normal);
- GLOBALVALUEDEF (int, xyzzy,123);
- #ifdef __GNUC__
- #define ss$_normal ((int) ss$_normal)
- #define xyzzy ((int) xyzzy)
- #endif
-
- Don't use `globaldef' or `globalref' with a variable whose type is
-an enumeration type; this is not implemented. Instead, make the
-variable an integer, and use a `globalvaluedef' for each of the
-enumeration values. An example of this would be:
-
- #ifdef __GNUC__
- GLOBALDEF (int, color, 0);
- GLOBALVALUEDEF (int, RED, 0);
- GLOBALVALUEDEF (int, BLUE, 1);
- GLOBALVALUEDEF (int, GREEN, 3);
- #else
- enum globaldef color {RED, BLUE, GREEN = 3};
- #endif
-
-\1f
-File: gcc.info, Node: VMS Misc, Prev: Global Declarations, Up: VMS
-
-Other VMS Issues
-================
-
- GCC automatically arranges for `main' to return 1 by default if you
-fail to specify an explicit return value. This will be interpreted by
-VMS as a status code indicating a normal successful completion.
-Version 1 of GCC did not provide this default.
-
- GCC on VMS works only with the GNU assembler, GAS. You need version
-1.37 or later of GAS in order to produce value debugging information for
-the VMS debugger. Use the ordinary VMS linker with the object files
-produced by GAS.
-
- Under previous versions of GCC, the generated code would occasionally
-give strange results when linked to the sharable `VAXCRTL' library.
-Now this should work.
-
- A caveat for use of `const' global variables: the `const' modifier
-must be specified in every external declaration of the variable in all
-of the source files that use that variable. Otherwise the linker will
-issue warnings about conflicting attributes for the variable. Your
-program will still work despite the warnings, but the variable will be
-placed in writable storage.
-
- Although the VMS linker does distinguish between upper and lower case
-letters in global symbols, most VMS compilers convert all such symbols
-into upper case and most run-time library routines also have upper case
-names. To be able to reliably call such routines, GCC (by means of the
-assembler GAS) converts global symbols into upper case like other VMS
-compilers. However, since the usual practice in C is to distinguish
-case, GCC (via GAS) tries to preserve usual C behavior by augmenting
-each name that is not all lower case. This means truncating the name
-to at most 23 characters and then adding more characters at the end
-which encode the case pattern of those 23. Names which contain at
-least one dollar sign are an exception; they are converted directly into
-upper case without augmentation.
-
- Name augmentation yields bad results for programs that use
-precompiled libraries (such as Xlib) which were generated by another
-compiler. You can use the compiler option `/NOCASE_HACK' to inhibit
-augmentation; it makes external C functions and variables
-case-independent as is usual on VMS. Alternatively, you could write
-all references to the functions and variables in such libraries using
-lower case; this will work on VMS, but is not portable to other
-systems. The compiler option `/NAMES' also provides control over
-global name handling.
-
- Function and variable names are handled somewhat differently with
-G++. The GNU C++ compiler performs "name mangling" on function names,
-which means that it adds information to the function name to describe
-the data types of the arguments that the function takes. One result of
-this is that the name of a function can become very long. Since the
-VMS linker only recognizes the first 31 characters in a name, special
-action is taken to ensure that each function and variable has a unique
-name that can be represented in 31 characters.
-
- If the name (plus a name augmentation, if required) is less than 32
-characters in length, then no special action is performed. If the name
-is longer than 31 characters, the assembler (GAS) will generate a hash
-string based upon the function name, truncate the function name to 23
-characters, and append the hash string to the truncated name. If the
-`/VERBOSE' compiler option is used, the assembler will print both the
-full and truncated names of each symbol that is truncated.
-
- The `/NOCASE_HACK' compiler option should not be used when you are
-compiling programs that use libg++. libg++ has several instances of
-objects (i.e. `Filebuf' and `filebuf') which become indistinguishable
-in a case-insensitive environment. This leads to cases where you need
-to inhibit augmentation selectively (if you were using libg++ and Xlib
-in the same program, for example). There is no special feature for
-doing this, but you can get the result by defining a macro for each
-mixed case symbol for which you wish to inhibit augmentation. The
-macro should expand into the lower case equivalent of itself. For
-example:
-
- #define StuDlyCapS studlycaps
-
- These macro definitions can be placed in a header file to minimize
-the number of changes to your source code.
-
-\1f
-File: gcc.info, Node: Funding, Next: GNU Project, Prev: VMS, Up: Top
-
-Funding Free Software
-*********************
-
- If you want to have more free software a few years from now, it makes
-sense for you to help encourage people to contribute funds for its
-development. The most effective approach known is to encourage
-commercial redistributors to donate.
-
- Users of free software systems can boost the pace of development by
-encouraging for-a-fee distributors to donate part of their selling price
-to free software developers--the Free Software Foundation, and others.
-
- The way to convince distributors to do this is to demand it and
-expect it from them. So when you compare distributors, judge them
-partly by how much they give to free software development. Show
-distributors they must compete to be the one who gives the most.
-
- To make this approach work, you must insist on numbers that you can
-compare, such as, "We will donate ten dollars to the Frobnitz project
-for each disk sold." Don't be satisfied with a vague promise, such as
-"A portion of the profits are donated," since it doesn't give a basis
-for comparison.
-
- Even a precise fraction "of the profits from this disk" is not very
-meaningful, since creative accounting and unrelated business decisions
-can greatly alter what fraction of the sales price counts as profit.
-If the price you pay is $50, ten percent of the profit is probably less
-than a dollar; it might be a few cents, or nothing at all.
-
- Some redistributors do development work themselves. This is useful
-too; but to keep everyone honest, you need to inquire how much they do,
-and what kind. Some kinds of development make much more long-term
-difference than others. For example, maintaining a separate version of
-a program contributes very little; maintaining the standard version of a
-program for the whole community contributes much. Easy new ports
-contribute little, since someone else would surely do them; difficult
-ports such as adding a new CPU to the GNU Compiler Collection
-contribute more; major new features or packages contribute the most.
-
- By establishing the idea that supporting further development is "the
-proper thing to do" when distributing free software for a fee, we can
-assure a steady flow of resources into making more free software.
-
- Copyright (C) 1994 Free Software Foundation, Inc.
- Verbatim copying and redistribution of this section is permitted
- without royalty; alteration is not permitted.
-
-\1f
-File: gcc.info, Node: GNU Project, Next: Copying, Prev: Funding, Up: Top
-
-The GNU Project and GNU/Linux
-*****************************
-
- The GNU Project was launched in 1984 to develop a complete Unix-like
-operating system which is free software: the GNU system. (GNU is a
-recursive acronym for "GNU's Not Unix"; it is pronounced "guh-NEW".)
-Variants of the GNU operating system, which use the kernel Linux, are
-now widely used; though these systems are often referred to as "Linux",
-they are more accurately called GNU/Linux systems.
-
- For more information, see:
- `http://www.gnu.org/'
- `http://www.gnu.org/gnu/linux-and-gnu.html'
-
-\1f
-File: gcc.info, Node: Copying, Next: GNU Free Documentation License, Prev: GNU Project, Up: Top
-
-GNU GENERAL PUBLIC LICENSE
-**************************
-
- Version 2, June 1991
- Copyright (C) 1989, 1991 Free Software Foundation, Inc.
- 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
-
- Everyone is permitted to copy and distribute verbatim copies
- of this license document, but changing it is not allowed.
-
-Preamble
-========
-
- The licenses for most software are designed to take away your
-freedom to share and change it. By contrast, the GNU General Public
-License is intended to guarantee your freedom to share and change free
-software--to make sure the software is free for all its users. This
-General Public License applies to most of the Free Software
-Foundation's software and to any other program whose authors commit to
-using it. (Some other Free Software Foundation software is covered by
-the GNU Library General Public License instead.) You can apply it to
-your programs, too.
-
- When we speak of free software, we are referring to freedom, not
-price. Our General Public Licenses are designed to make sure that you
-have the freedom to distribute copies of free software (and charge for
-this service if you wish), that you receive source code or can get it
-if you want it, that you can change the software or use pieces of it in
-new free programs; and that you know you can do these things.
-
- To protect your rights, we need to make restrictions that forbid
-anyone to deny you these rights or to ask you to surrender the rights.
-These restrictions translate to certain responsibilities for you if you
-distribute copies of the software, or if you modify it.
-
- For example, if you distribute copies of such a program, whether
-gratis or for a fee, you must give the recipients all the rights that
-you have. You must make sure that they, too, receive or can get the
-source code. And you must show them these terms so they know their
-rights.
-
- We protect your rights with two steps: (1) copyright the software,
-and (2) offer you this license which gives you legal permission to copy,
-distribute and/or modify the software.
-
- Also, for each author's protection and ours, we want to make certain
-that everyone understands that there is no warranty for this free
-software. If the software is modified by someone else and passed on, we
-want its recipients to know that what they have is not the original, so
-that any problems introduced by others will not reflect on the original
-authors' reputations.
-
- Finally, any free program is threatened constantly by software
-patents. We wish to avoid the danger that redistributors of a free
-program will individually obtain patent licenses, in effect making the
-program proprietary. To prevent this, we have made it clear that any
-patent must be licensed for everyone's free use or not licensed at all.
-
- The precise terms and conditions for copying, distribution and
-modification follow.
-
- TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
- 0. This License applies to any program or other work which contains a
- notice placed by the copyright holder saying it may be distributed
- under the terms of this General Public License. The "Program",
- below, refers to any such program or work, and a "work based on
- the Program" means either the Program or any derivative work under
- copyright law: that is to say, a work containing the Program or a
- portion of it, either verbatim or with modifications and/or
- translated into another language. (Hereinafter, translation is
- included without limitation in the term "modification".) Each
- licensee is addressed as "you".
-
- Activities other than copying, distribution and modification are
- not covered by this License; they are outside its scope. The act
- of running the Program is not restricted, and the output from the
- Program is covered only if its contents constitute a work based on
- the Program (independent of having been made by running the
- Program). Whether that is true depends on what the Program does.
-
- 1. You may copy and distribute verbatim copies of the Program's
- source code as you receive it, in any medium, provided that you
- conspicuously and appropriately publish on each copy an appropriate
- copyright notice and disclaimer of warranty; keep intact all the
- notices that refer to this License and to the absence of any
- warranty; and give any other recipients of the Program a copy of
- this License along with the Program.
-
- You may charge a fee for the physical act of transferring a copy,
- and you may at your option offer warranty protection in exchange
- for a fee.
-
- 2. You may modify your copy or copies of the Program or any portion
- of it, thus forming a work based on the Program, and copy and
- distribute such modifications or work under the terms of Section 1
- above, provided that you also meet all of these conditions:
-
- a. You must cause the modified files to carry prominent notices
- stating that you changed the files and the date of any change.
-
- b. You must cause any work that you distribute or publish, that
- in whole or in part contains or is derived from the Program
- or any part thereof, to be licensed as a whole at no charge
- to all third parties under the terms of this License.
-
- c. If the modified program normally reads commands interactively
- when run, you must cause it, when started running for such
- interactive use in the most ordinary way, to print or display
- an announcement including an appropriate copyright notice and
- a notice that there is no warranty (or else, saying that you
- provide a warranty) and that users may redistribute the
- program under these conditions, and telling the user how to
- view a copy of this License. (Exception: if the Program
- itself is interactive but does not normally print such an
- announcement, your work based on the Program is not required
- to print an announcement.)
-
- These requirements apply to the modified work as a whole. If
- identifiable sections of that work are not derived from the
- Program, and can be reasonably considered independent and separate
- works in themselves, then this License, and its terms, do not
- apply to those sections when you distribute them as separate
- works. But when you distribute the same sections as part of a
- whole which is a work based on the Program, the distribution of
- the whole must be on the terms of this License, whose permissions
- for other licensees extend to the entire whole, and thus to each
- and every part regardless of who wrote it.
-
- Thus, it is not the intent of this section to claim rights or
- contest your rights to work written entirely by you; rather, the
- intent is to exercise the right to control the distribution of
- derivative or collective works based on the Program.
-
- In addition, mere aggregation of another work not based on the
- Program with the Program (or with a work based on the Program) on
- a volume of a storage or distribution medium does not bring the
- other work under the scope of this License.
-
- 3. You may copy and distribute the Program (or a work based on it,
- under Section 2) in object code or executable form under the terms
- of Sections 1 and 2 above provided that you also do one of the
- following:
-
- a. Accompany it with the complete corresponding machine-readable
- source code, which must be distributed under the terms of
- Sections 1 and 2 above on a medium customarily used for
- software interchange; or,
-
- b. Accompany it with a written offer, valid for at least three
- years, to give any third party, for a charge no more than your
- cost of physically performing source distribution, a complete
- machine-readable copy of the corresponding source code, to be
- distributed under the terms of Sections 1 and 2 above on a
- medium customarily used for software interchange; or,
-
- c. Accompany it with the information you received as to the offer
- to distribute corresponding source code. (This alternative is
- allowed only for noncommercial distribution and only if you
- received the program in object code or executable form with
- such an offer, in accord with Subsection b above.)
-
- The source code for a work means the preferred form of the work for
- making modifications to it. For an executable work, complete
- source code means all the source code for all modules it contains,
- plus any associated interface definition files, plus the scripts
- used to control compilation and installation of the executable.
- However, as a special exception, the source code distributed need
- not include anything that is normally distributed (in either
- source or binary form) with the major components (compiler,
- kernel, and so on) of the operating system on which the executable
- runs, unless that component itself accompanies the executable.
-
- If distribution of executable or object code is made by offering
- access to copy from a designated place, then offering equivalent
- access to copy the source code from the same place counts as
- distribution of the source code, even though third parties are not
- compelled to copy the source along with the object code.
-
- 4. You may not copy, modify, sublicense, or distribute the Program
- except as expressly provided under this License. Any attempt
- otherwise to copy, modify, sublicense or distribute the Program is
- void, and will automatically terminate your rights under this
- License. However, parties who have received copies, or rights,
- from you under this License will not have their licenses
- terminated so long as such parties remain in full compliance.
-
- 5. You are not required to accept this License, since you have not
- signed it. However, nothing else grants you permission to modify
- or distribute the Program or its derivative works. These actions
- are prohibited by law if you do not accept this License.
- Therefore, by modifying or distributing the Program (or any work
- based on the Program), you indicate your acceptance of this
- License to do so, and all its terms and conditions for copying,
- distributing or modifying the Program or works based on it.
-
- 6. Each time you redistribute the Program (or any work based on the
- Program), the recipient automatically receives a license from the
- original licensor to copy, distribute or modify the Program
- subject to these terms and conditions. You may not impose any
- further restrictions on the recipients' exercise of the rights
- granted herein. You are not responsible for enforcing compliance
- by third parties to this License.
-
- 7. If, as a consequence of a court judgment or allegation of patent
- infringement or for any other reason (not limited to patent
- issues), conditions are imposed on you (whether by court order,
- agreement or otherwise) that contradict the conditions of this
- License, they do not excuse you from the conditions of this
- License. If you cannot distribute so as to satisfy simultaneously
- your obligations under this License and any other pertinent
- obligations, then as a consequence you may not distribute the
- Program at all. For example, if a patent license would not permit
- royalty-free redistribution of the Program by all those who
- receive copies directly or indirectly through you, then the only
- way you could satisfy both it and this License would be to refrain
- entirely from distribution of the Program.
-
- If any portion of this section is held invalid or unenforceable
- under any particular circumstance, the balance of the section is
- intended to apply and the section as a whole is intended to apply
- in other circumstances.
-
- It is not the purpose of this section to induce you to infringe any
- patents or other property right claims or to contest validity of
- any such claims; this section has the sole purpose of protecting
- the integrity of the free software distribution system, which is
- implemented by public license practices. Many people have made
- generous contributions to the wide range of software distributed
- through that system in reliance on consistent application of that
- system; it is up to the author/donor to decide if he or she is
- willing to distribute software through any other system and a
- licensee cannot impose that choice.
-
- This section is intended to make thoroughly clear what is believed
- to be a consequence of the rest of this License.
-
- 8. If the distribution and/or use of the Program is restricted in
- certain countries either by patents or by copyrighted interfaces,
- the original copyright holder who places the Program under this
- License may add an explicit geographical distribution limitation
- excluding those countries, so that distribution is permitted only
- in or among countries not thus excluded. In such case, this
- License incorporates the limitation as if written in the body of
- this License.
-
- 9. The Free Software Foundation may publish revised and/or new
- versions of the General Public License from time to time. Such
- new versions will be similar in spirit to the present version, but
- may differ in detail to address new problems or concerns.
-
- Each version is given a distinguishing version number. If the
- Program specifies a version number of this License which applies
- to it and "any later version", you have the option of following
- the terms and conditions either of that version or of any later
- version published by the Free Software Foundation. If the Program
- does not specify a version number of this License, you may choose
- any version ever published by the Free Software Foundation.
-
- 10. If you wish to incorporate parts of the Program into other free
- programs whose distribution conditions are different, write to the
- author to ask for permission. For software which is copyrighted
- by the Free Software Foundation, write to the Free Software
- Foundation; we sometimes make exceptions for this. Our decision
- will be guided by the two goals of preserving the free status of
- all derivatives of our free software and of promoting the sharing
- and reuse of software generally.
-
- NO WARRANTY
-
- 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
- WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
- LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
- HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT
- WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT
- NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
- FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE
- QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
- PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
- SERVICING, REPAIR OR CORRECTION.
-
- 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
- WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
- MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
- LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
- INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
- INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
- DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
- OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY
- OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
- ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
-
- END OF TERMS AND CONDITIONS
-
-How to Apply These Terms to Your New Programs
-=============================================
-
- If you develop a new program, and you want it to be of the greatest
-possible use to the public, the best way to achieve this is to make it
-free software which everyone can redistribute and change under these
-terms.
-
- To do so, attach the following notices to the program. It is safest
-to attach them to the start of each source file to most effectively
-convey the exclusion of warranty; and each file should have at least
-the "copyright" line and a pointer to where the full notice is found.
-
- ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
- Copyright (C) YEAR NAME OF AUTHOR
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software
- Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA.
-
- Also add information on how to contact you by electronic and paper
-mail.
-
- If the program is interactive, make it output a short notice like
-this when it starts in an interactive mode:
-
- Gnomovision version 69, Copyright (C) YEAR NAME OF AUTHOR
- Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
- type `show w'.
- This is free software, and you are welcome to redistribute it
- under certain conditions; type `show c' for details.
-
- The hypothetical commands `show w' and `show c' should show the
-appropriate parts of the General Public License. Of course, the
-commands you use may be called something other than `show w' and `show
-c'; they could even be mouse-clicks or menu items--whatever suits your
-program.
-
- You should also get your employer (if you work as a programmer) or
-your school, if any, to sign a "copyright disclaimer" for the program,
-if necessary. Here is a sample; alter the names:
-
- Yoyodyne, Inc., hereby disclaims all copyright interest in the program
- `Gnomovision' (which makes passes at compilers) written by James Hacker.
-
- SIGNATURE OF TY COON, 1 April 1989
- Ty Coon, President of Vice
-
- This General Public License does not permit incorporating your
-program into proprietary programs. If your program is a subroutine
-library, you may consider it more useful to permit linking proprietary
-applications with the library. If this is what you want to do, use the
-GNU Library General Public License instead of this License.
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: GNU Free Documentation License, Next: Contributors, Prev: Copying, Up: Top
-
-GNU Free Documentation License
-******************************
-
- Version 1.1, March 2000
- Copyright (C) 2000 Free Software Foundation, Inc.
- 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
-
- Everyone is permitted to copy and distribute verbatim copies
- of this license document, but changing it is not allowed.
-
- 0. PREAMBLE
-
- The purpose of this License is to make a manual, textbook, or other
- written document "free" in the sense of freedom: to assure everyone
- the effective freedom to copy and redistribute it, with or without
- modifying it, either commercially or noncommercially. Secondarily,
- this License preserves for the author and publisher a way to get
- credit for their work, while not being considered responsible for
- modifications made by others.
-
- This License is a kind of "copyleft", which means that derivative
- works of the document must themselves be free in the same sense.
- It complements the GNU General Public License, which is a copyleft
- license designed for free software.
-
- We have designed this License in order to use it for manuals for
- free software, because free software needs free documentation: a
- free program should come with manuals providing the same freedoms
- that the software does. But this License is not limited to
- software manuals; it can be used for any textual work, regardless
- of subject matter or whether it is published as a printed book.
- We recommend this License principally for works whose purpose is
- instruction or reference.
-
- 1. APPLICABILITY AND DEFINITIONS
-
- This License applies to any manual or other work that contains a
- notice placed by the copyright holder saying it can be distributed
- under the terms of this License. The "Document", below, refers to
- any such manual or work. Any member of the public is a licensee,
- and is addressed as "you".
-
- A "Modified Version" of the Document means any work containing the
- Document or a portion of it, either copied verbatim, or with
- modifications and/or translated into another language.
-
- A "Secondary Section" is a named appendix or a front-matter
- section of the Document that deals exclusively with the
- relationship of the publishers or authors of the Document to the
- Document's overall subject (or to related matters) and contains
- nothing that could fall directly within that overall subject.
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- mathematics, a Secondary Section may not explain any mathematics.)
- The relationship could be a matter of historical connection with
- the subject or with related matters, or of legal, commercial,
- philosophical, ethical or political position regarding them.
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- The "Invariant Sections" are certain Secondary Sections whose
- titles are designated, as being those of Invariant Sections, in
- the notice that says that the Document is released under this
- License.
-
- The "Cover Texts" are certain short passages of text that are
- listed, as Front-Cover Texts or Back-Cover Texts, in the notice
- that says that the Document is released under this License.
-
- A "Transparent" copy of the Document means a machine-readable copy,
- represented in a format whose specification is available to the
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- plus such following pages as are needed to hold, legibly, the
- material this License requires to appear in the title page. For
- works in formats which do not have any title page as such, "Title
- Page" means the text near the most prominent appearance of the
- work's title, preceding the beginning of the body of the text.
-
- 2. VERBATIM COPYING
-
- You may copy and distribute the Document in any medium, either
- commercially or noncommercially, provided that this License, the
- copyright notices, and the license notice saying this License
- applies to the Document are reproduced in all copies, and that you
- add no other conditions whatsoever to those of this License. You
- may not use technical measures to obstruct or control the reading
- or further copying of the copies you make or distribute. However,
- you may accept compensation in exchange for copies. If you
- distribute a large enough number of copies you must also follow
- the conditions in section 3.
-
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- and you may publicly display copies.
-
- 3. COPYING IN QUANTITY
-
- If you publish printed copies of the Document numbering more than
- 100, and the Document's license notice requires Cover Texts, you
- must enclose the copies in covers that carry, clearly and legibly,
- all these Cover Texts: Front-Cover Texts on the front cover, and
- Back-Cover Texts on the back cover. Both covers must also clearly
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- front cover must present the full title with all words of the
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- satisfy these conditions, can be treated as verbatim copying in
- other respects.
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- numbering more than 100, you must either include a
- machine-readable Transparent copy along with each Opaque copy, or
- state in or with each Opaque copy a publicly-accessible
- computer-network location containing a complete Transparent copy
- of the Document, free of added material, which the general
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- begin distribution of Opaque copies in quantity, to ensure that
- this Transparent copy will remain thus accessible at the stated
- location until at least one year after the last time you
- distribute an Opaque copy (directly or through your agents or
- retailers) of that edition to the public.
-
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- the Document well before redistributing any large number of
- copies, to give them a chance to provide you with an updated
- version of the Document.
-
- 4. MODIFICATIONS
-
- You may copy and distribute a Modified Version of the Document
- under the conditions of sections 2 and 3 above, provided that you
- release the Modified Version under precisely this License, with
- the Modified Version filling the role of the Document, thus
- licensing distribution and modification of the Modified Version to
- whoever possesses a copy of it. In addition, you must do these
- things in the Modified Version:
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- A. Use in the Title Page (and on the covers, if any) a title
- distinct from that of the Document, and from those of
- previous versions (which should, if there were any, be listed
- in the History section of the Document). You may use the
- same title as a previous version if the original publisher of
- that version gives permission.
-
- B. List on the Title Page, as authors, one or more persons or
- entities responsible for authorship of the modifications in
- the Modified Version, together with at least five of the
- principal authors of the Document (all of its principal
- authors, if it has less than five).
-
- C. State on the Title page the name of the publisher of the
- Modified Version, as the publisher.
-
- D. Preserve all the copyright notices of the Document.
-
- E. Add an appropriate copyright notice for your modifications
- adjacent to the other copyright notices.
-
- F. Include, immediately after the copyright notices, a license
- notice giving the public permission to use the Modified
- Version under the terms of this License, in the form shown in
- the Addendum below.
-
- G. Preserve in that license notice the full lists of Invariant
- Sections and required Cover Texts given in the Document's
- license notice.
-
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-
- I. Preserve the section entitled "History", and its title, and
- add to it an item stating at least the title, year, new
- authors, and publisher of the Modified Version as given on
- the Title Page. If there is no section entitled "History" in
- the Document, create one stating the title, year, authors,
- and publisher of the Document as given on its Title Page,
- then add an item describing the Modified Version as stated in
- the previous sentence.
-
- J. Preserve the network location, if any, given in the Document
- for public access to a Transparent copy of the Document, and
- likewise the network locations given in the Document for
- previous versions it was based on. These may be placed in
- the "History" section. You may omit a network location for a
- work that was published at least four years before the
- Document itself, or if the original publisher of the version
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- preserve the section's title, and preserve in the section all
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- or the equivalent are not considered part of the section
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- must delete all sections entitled "Endorsements."
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- 6. COLLECTIONS OF DOCUMENTS
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- copies of this License in the various documents with a single copy
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- original versions of these Invariant Sections. You may include a
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- disagreement between the translation and the original English
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- except as expressly provided for under this License. Any other
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- void, and will automatically terminate your rights under this
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- or any later version published by the Free Software Foundation;
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-\1f
-File: gcc.info, Node: Contributors, Next: Option Index, Prev: GNU Free Documentation License, Up: Top
-
-Contributors to GCC
-*******************
-
- The GCC project would like to thank its many contributors. Without
-them the project would not have been nearly as successful as it has
-been. Any omissions in this list are accidental. Feel free to contact
-<law@redhat.com> if you have been left out or some of your
-contributions are not listed. Please keep this list in alphabetical
-order.
-
- * Analog Devices helped implement the support for complex data types
- and iterators.
-
- * John David Anglin for threading-related fixes and improvements to
- libstdc++-v3, and the HP-UX port.
-
- * James van Artsdalen wrote the code that makes efficient use of the
- Intel 80387 register stack.
-
- * Alasdair Baird for various bugfixes.
-
- * Gerald Baumgartner added the signature extension to the C++ front
- end.
-
- * Godmar Back for his Java improvements and encouragement.
-
- * Scott Bambrough for help porting the Java compiler.
-
- * Jon Beniston for his Win32 port of Java.
-
- * Geoff Berry for his Java object serialization work and various
- patches.
-
- * Eric Blake for helping to make GCJ and libgcj conform to the
- specifications.
-
- * Hans-J. Boehm for his garbage collector, IA-64 libffi port, and
- other Java work.
-
- * Neil Booth for work on cpplib, lang hooks, debug hooks and other
- miscellaneous clean-ups.
-
- * Per Bothner for his direction via the steering committee and
- various improvements to our infrastructure for supporting new
- languages. Chill front end implementation. Initial
- implementations of cpplib, fix-header, config.guess, libio, and
- past C++ library (libg++) maintainer. Dreaming up, designing and
- implementing much of GCJ.
-
- * Devon Bowen helped port GCC to the Tahoe.
-
- * Don Bowman for mips-vxworks contributions.
-
- * Dave Brolley for work on cpplib and Chill.
-
- * Robert Brown implemented the support for Encore 32000 systems.
-
- * Christian Bruel for improvements to local store elimination.
-
- * Herman A.J. ten Brugge for various fixes.
-
- * Joerg Brunsmann for Java compiler hacking and help with the GCJ
- FAQ.
-
- * Joe Buck for his direction via the steering committee.
-
- * Craig Burley for leadership of the Fortran effort.
-
- * Stephan Buys for contributing Doxygen notes for libstdc++.
-
- * Paolo Carlini for libstdc++ work: lots of efficiency improvements
- to the string class, hard detective work on the frustrating
- localization issues, and keeping up with the problem reports.
-
- * John Carr for his alias work, SPARC hacking, infrastructure
- improvements, previous contributions to the steering committee,
- loop optimizations, etc.
-
- * Steve Chamberlain for support for the Hitachi SH and H8 processors
- and the PicoJava processor, and for GCJ config fixes.
-
- * Glenn Chambers for help with the GCJ FAQ.
-
- * John-Marc Chandonia for various libgcj patches.
-
- * Scott Christley for his Objective-C contributions.
-
- * Eric Christopher for his Java porting help and clean-ups.
-
- * Branko Cibej for more warning contributions.
-
- * The GNU Classpath project for all of their merged runtime code.
-
- * Nick Clifton for arm, mcore, fr30, v850, m32r work, `--help', and
- other random hacking.
-
- * Michael Cook for libstdc++ cleanup patches to reduce warnings.
-
- * Ralf Corsepius for SH testing and minor bugfixing.
-
- * Stan Cox for care and feeding of the x86 port and lots of behind
- the scenes hacking.
-
- * Alex Crain provided changes for the 3b1.
-
- * Ian Dall for major improvements to the NS32k port.
-
- * Dario Dariol contributed the four varieties of sample programs
- that print a copy of their source.
-
- * Russell Davidson for fstream and stringstream fixes in libstdc++.
-
- * Mo DeJong for GCJ and libgcj bug fixes.
-
- * Gabriel Dos Reis for contributions to g++, contributions and
- maintenance of GCC diagnostics infrastructure, libstdc++-v3,
- including valarray<>, complex<>, maintaining the numerics library
- (including that pesky <limits> :-) and keeping up-to-date anything
- to do with numbers.
-
- * Ulrich Drepper for his work on glibc, testing of GCC using glibc,
- ISO C99 support, CFG dumping support, etc., plus support of the
- C++ runtime libraries including for all kinds of C interface
- issues, contributing and maintaining complex<>, sanity checking
- and disbursement, configuration architecture, libio maintenance,
- and early math work.
-
- * Richard Earnshaw for his ongoing work with the ARM.
-
- * David Edelsohn for his direction via the steering committee,
- ongoing work with the RS6000/PowerPC port, help cleaning up Haifa
- loop changes, and for doing the entire AIX port of libstdc++ with
- his bare hands.
-
- * Kevin Ediger for the floating point formatting of num_put::do_put
- in libstdc++.
-
- * Phil Edwards for libstdc++ work including configuration hackery,
- documentation maintainer, chief breaker of the web pages, the
- occasional iostream bugfix, and work on shared library symbol
- versioning.
-
- * Paul Eggert for random hacking all over GCC.
-
- * Mark Elbrecht for various DJGPP improvements, and for libstdc++
- configuration support for locales and fstream-related fixes.
-
- * Vadim Egorov for libstdc++ fixes in strings, streambufs, and
- iostreams.
-
- * Ben Elliston for his work to move the Objective-C runtime into its
- own subdirectory and for his work on autoconf.
-
- * Marc Espie for OpenBSD support.
-
- * Doug Evans for much of the global optimization framework, arc,
- m32r, and SPARC work.
-
- * Fred Fish for BeOS support and Ada fixes.
-
- * Ivan Fontes Garcia for the Portugese translation of the GCJ FAQ.
-
- * Peter Gerwinski for various bugfixes and the Pascal front end.
-
- * Kaveh Ghazi for his direction via the steering committee and
- amazing work to make `-W -Wall' useful.
-
- * John Gilmore for a donation to the FSF earmarked improving GNU
- Java.
-
- * Judy Goldberg for c++ contributions.
-
- * Torbjorn Granlund for various fixes and the c-torture testsuite,
- multiply- and divide-by-constant optimization, improved long long
- support, improved leaf function register allocation, and his
- direction via the steering committee.
-
- * Anthony Green for his `-Os' contributions and Java front end work.
-
- * Stu Grossman for gdb hacking, allowing GCJ developers to debug our
- code.
-
- * Michael K. Gschwind contributed the port to the PDP-11.
-
- * Ron Guilmette implemented the `protoize' and `unprotoize' tools,
- the support for Dwarf symbolic debugging information, and much of
- the support for System V Release 4. He has also worked heavily on
- the Intel 386 and 860 support.
-
- * Bruno Haible for improvements in the runtime overhead for EH, new
- warnings and assorted bugfixes.
-
- * Andrew Haley for his amazing Java compiler and library efforts.
-
- * Chris Hanson assisted in making GCC work on HP-UX for the 9000
- series 300.
-
- * Michael Hayes for various thankless work he's done trying to get
- the c30/c40 ports functional. Lots of loop and unroll
- improvements and fixes.
-
- * Kate Hedstrom for staking the g77 folks with an initial testsuite.
-
- * Richard Henderson for his ongoing SPARC, alpha, and ia32 work, loop
- opts, and generally fixing lots of old problems we've ignored for
- years, flow rewrite and lots of further stuff, including reviewing
- tons of patches.
-
- * Nobuyuki Hikichi of Software Research Associates, Tokyo,
- contributed the support for the Sony NEWS machine.
-
- * Manfred Hollstein for his ongoing work to keep the m88k alive, lots
- of testing an bugfixing, particularly of our configury code.
-
- * Steve Holmgren for MachTen patches.
-
- * Jan Hubicka for his x86 port improvements.
-
- * Christian Iseli for various bugfixes.
-
- * Kamil Iskra for general m68k hacking.
-
- * Lee Iverson for random fixes and MIPS testing.
-
- * Andreas Jaeger for various fixes to the MIPS port
-
- * Jakub Jelinek for his SPARC work and sibling call optimizations as
- well as lots of bug fixes and test cases, and for improving the
- Java build system.
-
- * Janis Johnson for ia64 testing and fixes and for her quality
- improvement sidetracks.
-
- * J. Kean Johnston for OpenServer support.
-
- * Tim Josling for the sample language treelang based originally on
- Richard Kenner's ""toy" language".
-
- * Nicolai Josuttis for additional libstdc++ documentation.
-
- * Klaus Kaempf for his ongoing work to make alpha-vms a viable
- target.
-
- * David Kashtan of SRI adapted GCC to VMS.
-
- * Ryszard Kabatek for many, many libstdc++ bugfixes and
- optimizations of strings, especially member functions, and for
- auto_ptr fixes.
-
- * Geoffrey Keating for his ongoing work to make the PPC work for
- GNU/Linux and his automatic regression tester.
-
- * Brendan Kehoe for his ongoing work with g++ and for a lot of early
- work in just about every part of libstdc++.
-
- * Oliver M. Kellogg of Deutsche Aerospace contributed the port to the
- MIL-STD-1750A.
-
- * Richard Kenner of the New York University Ultracomputer Research
- Laboratory wrote the machine descriptions for the AMD 29000, the
- DEC Alpha, the IBM RT PC, and the IBM RS/6000 as well as the
- support for instruction attributes. He also made changes to
- better support RISC processors including changes to common
- subexpression elimination, strength reduction, function calling
- sequence handling, and condition code support, in addition to
- generalizing the code for frame pointer elimination and delay slot
- scheduling. Richard Kenner was also the head maintainer of GCC
- for several years.
-
- * Mumit Khan for various contributions to the Cygwin and Mingw32
- ports and maintaining binary releases for Windows hosts, and for
- massive libstdc++ porting work to Cygwin/Mingw32.
-
- * Robin Kirkham for cpu32 support.
-
- * Mark Klein for PA improvements.
-
- * Thomas Koenig for various bugfixes.
-
- * Bruce Korb for the new and improved fixincludes code.
-
- * Benjamin Kosnik for his g++ work and for leading the libstdc++-v3
- effort.
-
- * Charles LaBrec contributed the support for the Integrated Solutions
- 68020 system.
-
- * Jeff Law for his direction via the steering committee,
- coordinating the entire egcs project and GCC 2.95, rolling out
- snapshots and releases, handling merges from GCC2, reviewing tons
- of patches that might have fallen through the cracks else, and
- random but extensive hacking.
-
- * Marc Lehmann for his direction via the steering committee and
- helping with analysis and improvements of x86 performance.
-
- * Ted Lemon wrote parts of the RTL reader and printer.
-
- * Kriang Lerdsuwanakij for improvements to demangler and various c++
- fixes.
-
- * Warren Levy for tremendous work on libgcj (Java Runtime Library)
- and random work on the Java front end.
-
- * Alain Lichnewsky ported GCC to the MIPS CPU.
-
- * Oskar Liljeblad for hacking on AWT and his many Java bug reports
- and patches.
-
- * Robert Lipe for OpenServer support, new testsuites, testing, etc.
-
- * Weiwen Liu for testing and various bugfixes.
-
- * Dave Love for his ongoing work with the Fortran front end and
- runtime libraries.
-
- * Martin von Lo"wis for internal consistency checking infrastructure,
- various C++ improvements including namespace support, and tons of
- assistance with libstdc++/compiler merges.
-
- * H.J. Lu for his previous contributions to the steering committee,
- many x86 bug reports, prototype patches, and keeping the GNU/Linux
- ports working.
-
- * Greg McGary for random fixes and (someday) bounded pointers.
-
- * Andrew MacLeod for his ongoing work in building a real EH system,
- various code generation improvements, work on the global
- optimizer, etc.
-
- * Vladimir Makarov for hacking some ugly i960 problems, PowerPC
- hacking improvements to compile-time performance, overall
- knowledge and direction in the area of instruction scheduling, and
- design and implementation of the automaton based instruction
- scheduler.
-
- * Bob Manson for his behind the scenes work on dejagnu.
-
- * Philip Martin for lots of libstdc++ string and vector iterator
- fixes and improvements, and string clean up and testsuites.
-
- * All of the Mauve project contributors, for Java test code.
-
- * Bryce McKinlay for numerous GCJ and libgcj fixes and improvements.
-
- * Adam Megacz for his work on the Win32 port of GCJ.
-
- * Michael Meissner for LRS framework, ia32, m32r, v850, m88k, MIPS,
- powerpc, haifa, ECOFF debug support, and other assorted hacking.
-
- * Jason Merrill for his direction via the steering committee and
- leading the g++ effort.
-
- * David Miller for his direction via the steering committee, lots of
- SPARC work, improvements in jump.c and interfacing with the Linux
- kernel developers.
-
- * Gary Miller ported GCC to Charles River Data Systems machines.
-
- * Alfred Minarik for libstdc++ string and ios bugfixes, and turning
- the entire libstdc++ testsuite namespace-compatible.
-
- * Mark Mitchell for his direction via the steering committee,
- mountains of C++ work, load/store hoisting out of loops, alias
- analysis improvements, ISO C `restrict' support, and serving as
- release manager for GCC 3.x.
-
- * Alan Modra for various GNU/Linux bits and testing.
-
- * Toon Moene for his direction via the steering committee, Fortran
- maintenance, and his ongoing work to make us make Fortran run fast.
-
- * Jason Molenda for major help in the care and feeding of all the
- services on the gcc.gnu.org (formerly egcs.cygnus.com)
- machine--mail, web services, ftp services, etc etc. Doing all
- this work on scrap paper and the backs of envelopes would have
- been... difficult.
-
- * Catherine Moore for fixing various ugly problems we have sent her
- way, including the haifa bug which was killing the Alpha & PowerPC
- Linux kernels.
-
- * Mike Moreton for his various Java patches.
-
- * David Mosberger-Tang for various Alpha improvements.
-
- * Stephen Moshier contributed the floating point emulator that
- assists in cross-compilation and permits support for floating
- point numbers wider than 64 bits and for ISO C99 support.
-
- * Bill Moyer for his behind the scenes work on various issues.
-
- * Philippe De Muyter for his work on the m68k port.
-
- * Joseph S. Myers for his work on the PDP-11 port, format checking
- and ISO C99 support, and continuous emphasis on (and contributions
- to) documentation.
-
- * Nathan Myers for his work on libstdc++-v3: architecture and
- authorship through the first three snapshots, including
- implementation of locale infrastructure, string, shadow C headers,
- and the initial project documentation (DESIGN, CHECKLIST, and so
- forth). Later, more work on MT-safe string and shadow headers.
-
- * Felix Natter for documentation on porting libstdc++.
-
- * NeXT, Inc. donated the front end that supports the Objective-C
- language.
-
- * Hans-Peter Nilsson for the CRIS and MMIX ports, improvements to
- the search engine setup, various documentation fixes and other
- small fixes.
-
- * Geoff Noer for this work on getting cygwin native builds working.
-
- * David O'Brien for the FreeBSD/alpha, FreeBSD/AMD x86-64,
- FreeBSD/ARM, FreeBSD/PowerPC, and FreeBSD/SPARC64 ports and
- related infrastructure improvements.
-
- * Alexandre Oliva for various build infrastructure improvements,
- scripts and amazing testing work, including keeping libtool issues
- sane and happy.
-
- * Melissa O'Neill for various NeXT fixes.
-
- * Rainer Orth for random MIPS work, including improvements to our o32
- ABI support, improvements to dejagnu's MIPS support, Java
- configuration clean-ups and porting work, etc.
-
- * Paul Petersen wrote the machine description for the Alliant FX/8.
-
- * Alexandre Petit-Bianco for implementing much of the Java compiler
- and continued Java maintainership.
-
- * Matthias Pfaller for major improvements to the NS32k port.
-
- * Gerald Pfeifer for his direction via the steering committee,
- pointing out lots of problems we need to solve, maintenance of the
- web pages, and taking care of documentation maintenance in general.
-
- * Ovidiu Predescu for his work on the Objective-C front end and
- runtime libraries.
-
- * Ken Raeburn for various improvements to checker, MIPS ports and
- various cleanups in the compiler.
-
- * Rolf W. Rasmussen for hacking on AWT.
-
- * David Reese of Sun Microsystems contributed to the Solaris on
- PowerPC port.
-
- * Joern Rennecke for maintaining the sh port, loop, regmove & reload
- hacking.
-
- * Loren J. Rittle for improvements to libstdc++-v3 including the
- FreeBSD port, threading fixes, thread-related configury changes,
- critical threading documentation, and solutions to really tricky
- I/O problems.
-
- * Craig Rodrigues for processing tons of bug reports.
-
- * Gavin Romig-Koch for lots of behind the scenes MIPS work.
-
- * Ken Rose for fixes to our delay slot filling code.
-
- * Paul Rubin wrote most of the preprocessor.
-
- * Chip Salzenberg for libstdc++ patches and improvements to locales,
- traits, Makefiles, libio, libtool hackery, and "long long" support.
-
- * Juha Sarlin for improvements to the H8 code generator.
-
- * Greg Satz assisted in making GCC work on HP-UX for the 9000 series
- 300.
-
- * Bradley Schatz for his work on the GCJ FAQ.
-
- * Peter Schauer wrote the code to allow debugging to work on the
- Alpha.
-
- * William Schelter did most of the work on the Intel 80386 support.
-
- * Bernd Schmidt for various code generation improvements and major
- work in the reload pass as well a serving as release manager for
- GCC 2.95.3.
-
- * Peter Schmid for constant testing of libstdc++ - especially
- application testing, going above and beyond what was requested for
- the release criteria - and libstdc++ header file tweaks.
-
- * Jason Schroeder for jcf-dump patches.
-
- * Andreas Schwab for his work on the m68k port.
-
- * Joel Sherrill for his direction via the steering committee, RTEMS
- contributions and RTEMS testing.
-
- * Nathan Sidwell for many C++ fixes/improvements.
-
- * Jeffrey Siegal for helping RMS with the original design of GCC,
- some code which handles the parse tree and RTL data structures,
- constant folding and help with the original VAX & m68k ports.
-
- * Kenny Simpson for prompting libstdc++ fixes due to defect reports
- from the LWG (thereby keeping us in line with updates from the
- ISO).
-
- * Franz Sirl for his ongoing work with making the PPC port stable
- for linux.
-
- * Andrey Slepuhin for assorted AIX hacking.
-
- * Christopher Smith did the port for Convex machines.
-
- * Randy Smith finished the Sun FPA support.
-
- * Scott Snyder for queue, iterator, istream, and string fixes and
- libstdc++ testsuite entries.
-
- * Brad Spencer for contributions to the GLIBCPP_FORCE_NEW technique.
-
- * Richard Stallman, for writing the original gcc and launching the
- GNU project.
-
- * Jan Stein of the Chalmers Computer Society provided support for
- Genix, as well as part of the 32000 machine description.
-
- * Nigel Stephens for various mips16 related fixes/improvements.
-
- * Jonathan Stone wrote the machine description for the Pyramid
- computer.
-
- * Graham Stott for various infrastructure improvements.
-
- * John Stracke for his Java HTTP protocol fixes.
-
- * Mike Stump for his Elxsi port, g++ contributions over the years
- and more recently his vxworks contributions
-
- * Jeff Sturm for Java porting help, bug fixes, and encouragement.
-
- * Shigeya Suzuki for this fixes for the bsdi platforms.
-
- * Ian Lance Taylor for his mips16 work, general configury hacking,
- fixincludes, etc.
-
- * Holger Teutsch provided the support for the Clipper CPU.
-
- * Gary Thomas for his ongoing work to make the PPC work for
- GNU/Linux.
-
- * Philipp Thomas for random bugfixes throughout the compiler
-
- * Jason Thorpe for thread support in libstdc++ on NetBSD.
-
- * Kresten Krab Thorup wrote the run time support for the Objective-C
- language and the fantastic Java bytecode interpreter.
-
- * Michael Tiemann for random bugfixes, the first instruction
- scheduler, initial C++ support, function integration, NS32k, SPARC
- and M88k machine description work, delay slot scheduling.
-
- * Andreas Tobler for his work porting libgcj to Darwin.
-
- * Teemu Torma for thread safe exception handling support.
-
- * Leonard Tower wrote parts of the parser, RTL generator, and RTL
- definitions, and of the VAX machine description.
-
- * Tom Tromey for internationalization support and for his many Java
- contributions and libgcj maintainership.
-
- * Lassi Tuura for improvements to config.guess to determine HP
- processor types.
-
- * Petter Urkedal for libstdc++ CXXFLAGS, math, and algorithms fixes.
-
- * Brent Verner for work with the libstdc++ cshadow files and their
- associated configure steps.
-
- * Todd Vierling for contributions for NetBSD ports.
-
- * Jonathan Wakely for contributing libstdc++ Doxygen notes and XHTML
- guidance.
-
- * Dean Wakerley for converting the install documentation from HTML
- to texinfo in time for GCC 3.0.
-
- * Krister Walfridsson for random bugfixes.
-
- * Stephen M. Webb for time and effort on making libstdc++ shadow
- files work with the tricky Solaris 8+ headers, and for pushing the
- build-time header tree.
-
- * John Wehle for various improvements for the x86 code generator,
- related infrastructure improvements to help x86 code generation,
- value range propagation and other work, WE32k port.
-
- * Zack Weinberg for major work on cpplib and various other bugfixes.
-
- * Matt Welsh for help with Linux Threads support in GCJ.
-
- * Urban Widmark for help fixing java.io.
-
- * Mark Wielaard for new Java library code and his work integrating
- with Classpath.
-
- * Dale Wiles helped port GCC to the Tahoe.
-
- * Bob Wilson from Tensilica, Inc. for the Xtensa port.
-
- * Jim Wilson for his direction via the steering committee, tackling
- hard problems in various places that nobody else wanted to work
- on, strength reduction and other loop optimizations.
-
- * Carlo Wood for various fixes.
-
- * Tom Wood for work on the m88k port.
-
- * Masanobu Yuhara of Fujitsu Laboratories implemented the machine
- description for the Tron architecture (specifically, the Gmicro).
-
- * Kevin Zachmann helped ported GCC to the Tahoe.
-
- * Gilles Zunino for help porting Java to Irix.
-
-
- We'd also like to thank the folks who have contributed time and
-energy in testing GCC:
-
- * Michael Abd-El-Malek
-
- * Thomas Arend
-
- * Bonzo Armstrong
-
- * Steven Ashe
-
- * Chris Baldwin
-
- * David Billinghurst
-
- * Jim Blandy
-
- * Stephane Bortzmeyer
-
- * Horst von Brand
-
- * Frank Braun
-
- * Rodney Brown
-
- * Joe Buck
-
- * Craig Burley
-
- * Sidney Cadot
-
- * Bradford Castalia
-
- * Ralph Doncaster
-
- * Ulrich Drepper
-
- * David Edelsohn
-
- * Richard Emberson
-
- * Levente Farkas
-
- * Graham Fawcett
-
- * Robert A. French
-
- * Jo"rgen Freyh
-
- * Mark K. Gardner
-
- * Charles-Antoine Gauthier
-
- * Yung Shing Gene
-
- * Kaveh Ghazi
-
- * David Gilbert
-
- * Simon Gornall
-
- * Fred Gray
-
- * John Griffin
-
- * Patrik Hagglund
-
- * Phil Hargett
-
- * Amancio Hasty
-
- * Bryan W. Headley
-
- * Kate Hedstrom
-
- * Richard Henderson
-
- * Kevin B. Hendricks
-
- * Manfred Hollstein
-
- * Kamil Iskra
-
- * Joep Jansen
-
- * Christian Joensson
-
- * David Kidd
-
- * Tobias Kuipers
-
- * Anand Krishnaswamy
-
- * Jeff Law
-
- * Robert Lipe
-
- * llewelly
-
- * Damon Love
-
- * Dave Love
-
- * H.J. Lu
-
- * Brad Lucier
-
- * Mumit Khan
-
- * Matthias Klose
-
- * Martin Knoblauch
-
- * Jesse Macnish
-
- * David Miller
-
- * Toon Moene
-
- * Stefan Morrell
-
- * Anon A. Mous
-
- * Matthias Mueller
-
- * Pekka Nikander
-
- * Alexandre Oliva
-
- * Jon Olson
-
- * Magnus Persson
-
- * Chris Pollard
-
- * Richard Polton
-
- * David Rees
-
- * Paul Reilly
-
- * Tom Reilly
-
- * Loren J. Rittle
-
- * Torsten Rueger
-
- * Danny Sadinoff
-
- * Marc Schifer
-
- * Peter Schmid
-
- * David Schuler
-
- * Vin Shelton
-
- * Franz Sirl
-
- * Tim Souder
-
- * Mike Stump
-
- * Adam Sulmicki
-
- * George Talbot
-
- * Gregory Warnes
-
- * Carlo Wood
-
- * David E. Young
-
- * And many others
-
- And finally we'd like to thank everyone who uses the compiler,
-submits bug reports and generally reminds us why we're doing this work
-in the first place.
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Option Index, Next: Index, Prev: Contributors, Up: Top
-
-Option Index
-************
-
- GCC's command line options are indexed here without any initial `-'
-or `--'. Where an option has both positive and negative forms (such as
-`-fOPTION' and `-fno-OPTION'), relevant entries in the manual are
-indexed under the most appropriate form; it may sometimes be useful to
-look up both forms.
-
-* Menu:
-
-* ###: Overall Options.
-* $: Preprocessor Options.
-* A: Preprocessor Options.
-* A-: Preprocessor Options.
-* ansi <1>: Non-bugs.
-* ansi <2>: Other Builtins.
-* ansi <3>: Preprocessor Options.
-* ansi <4>: C Dialect Options.
-* ansi: Standards.
-* aux-info: C Dialect Options.
-* b: Target Options.
-* B: Directory Options.
-* bcopy-builtin: PDP-11 Options.
-* c: Link Options.
-* C: Preprocessor Options.
-* c: Overall Options.
-* D: Preprocessor Options.
-* d: Debugging Options.
-* da: Debugging Options.
-* dA: Debugging Options.
-* dB: Debugging Options.
-* db: Debugging Options.
-* dC: Debugging Options.
-* dc: Debugging Options.
-* dD <1>: Preprocessor Options.
-* dD: Debugging Options.
-* dd: Debugging Options.
-* dE: Debugging Options.
-* de: Debugging Options.
-* dF: Debugging Options.
-* df: Debugging Options.
-* dG: Debugging Options.
-* dg: Debugging Options.
-* dh: Debugging Options.
-* dI: Preprocessor Options.
-* di: Debugging Options.
-* dj: Debugging Options.
-* dk: Debugging Options.
-* dL: Debugging Options.
-* dl: Debugging Options.
-* dM: Preprocessor Options.
-* dm: Debugging Options.
-* dM: Debugging Options.
-* dN <1>: Preprocessor Options.
-* dN: Debugging Options.
-* dn: Debugging Options.
-* do: Debugging Options.
-* dP: Debugging Options.
-* dp: Debugging Options.
-* dR: Debugging Options.
-* dr: Debugging Options.
-* dS: Debugging Options.
-* ds: Debugging Options.
-* dt: Debugging Options.
-* dumpmachine: Debugging Options.
-* dumpspecs: Debugging Options.
-* dumpversion: Debugging Options.
-* dv: Debugging Options.
-* dw: Debugging Options.
-* dx: Debugging Options.
-* dX: Debugging Options.
-* dy: Debugging Options.
-* dz: Debugging Options.
-* E <1>: Link Options.
-* E: Overall Options.
-* EB <1>: ARC Options.
-* EB: MIPS Options.
-* EL <1>: ARC Options.
-* EL: MIPS Options.
-* falign-functions: Optimize Options.
-* falign-jumps: Optimize Options.
-* falign-labels: Optimize Options.
-* falign-loops: Optimize Options.
-* fallow-single-precision: C Dialect Options.
-* falt-external-templates <1>: Template Instantiation.
-* falt-external-templates: C++ Dialect Options.
-* fargument-alias: Code Gen Options.
-* fargument-noalias: Code Gen Options.
-* fargument-noalias-global: Code Gen Options.
-* fbounds-check: Optimize Options.
-* fbranch-probabilities: Optimize Options.
-* fcall-saved <1>: Interoperation.
-* fcall-saved: Code Gen Options.
-* fcall-used: Code Gen Options.
-* fcaller-saves: Optimize Options.
-* fcheck-new: C++ Dialect Options.
-* fcond-mismatch: C Dialect Options.
-* fconserve-space: C++ Dialect Options.
-* fconstant-string-class: Objective-C Dialect Options.
-* fcse-follow-jumps: Optimize Options.
-* fcse-skip-blocks: Optimize Options.
-* fdata-sections: Optimize Options.
-* fdelayed-branch: Optimize Options.
-* fdelete-null-pointer-checks: Optimize Options.
-* fdiagnostics-show-location: Language Independent Options.
-* fdollars-in-identifiers <1>: Interoperation.
-* fdollars-in-identifiers: C++ Dialect Options.
-* fdump-class-hierarchy: Debugging Options.
-* fdump-translation-unit: Debugging Options.
-* fdump-tree: Debugging Options.
-* fdump-unnumbered: Debugging Options.
-* fexceptions: Code Gen Options.
-* fexpensive-optimizations: Optimize Options.
-* fexternal-templates <1>: Template Instantiation.
-* fexternal-templates: C++ Dialect Options.
-* ffast-math: Optimize Options.
-* ffixed: Code Gen Options.
-* ffloat-store <1>: Disappointments.
-* ffloat-store: Optimize Options.
-* ffor-scope: C++ Dialect Options.
-* fforce-addr: Optimize Options.
-* fforce-mem: Optimize Options.
-* ffreestanding <1>: Function Attributes.
-* ffreestanding <2>: C Dialect Options.
-* ffreestanding: Standards.
-* ffunction-sections: Optimize Options.
-* fgcse: Optimize Options.
-* fgcse-lm: Optimize Options.
-* fgcse-sm: Optimize Options.
-* fgnu-runtime: Objective-C Dialect Options.
-* fhosted: C Dialect Options.
-* finhibit-size-directive: Code Gen Options.
-* finline-functions: Optimize Options.
-* finline-limit: Optimize Options.
-* finstrument-functions <1>: Function Attributes.
-* finstrument-functions: Code Gen Options.
-* fkeep-inline-functions <1>: Inline.
-* fkeep-inline-functions: Optimize Options.
-* fkeep-static-consts: Optimize Options.
-* fleading-underscore: Code Gen Options.
-* fmem-report: Debugging Options.
-* fmessage-length: Language Independent Options.
-* fmove-all-movables: Optimize Options.
-* fms-extensions: C++ Dialect Options.
-* fnext-runtime: Objective-C Dialect Options.
-* fno-access-control: C++ Dialect Options.
-* fno-asm: C Dialect Options.
-* fno-branch-count-reg: Optimize Options.
-* fno-builtin <1>: Other Builtins.
-* fno-builtin: C Dialect Options.
-* fno-common <1>: Variable Attributes.
-* fno-common: Code Gen Options.
-* fno-const-strings: C++ Dialect Options.
-* fno-cprop-registers: Optimize Options.
-* fno-default-inline <1>: Inline.
-* fno-default-inline <2>: Optimize Options.
-* fno-default-inline: C++ Dialect Options.
-* fno-defer-pop: Optimize Options.
-* fno-elide-constructors: C++ Dialect Options.
-* fno-enforce-eh-specs: C++ Dialect Options.
-* fno-for-scope: C++ Dialect Options.
-* fno-function-cse: Optimize Options.
-* fno-gnu-keywords: C++ Dialect Options.
-* fno-gnu-linker: Code Gen Options.
-* fno-guess-branch-probability: Optimize Options.
-* fno-ident: Code Gen Options.
-* fno-implement-inlines <1>: C++ Interface.
-* fno-implement-inlines: C++ Dialect Options.
-* fno-implicit-inline-templates: C++ Dialect Options.
-* fno-implicit-templates <1>: Template Instantiation.
-* fno-implicit-templates: C++ Dialect Options.
-* fno-inline: Optimize Options.
-* fno-math-errno: Optimize Options.
-* fno-nonansi-builtins: C++ Dialect Options.
-* fno-operator-names: C++ Dialect Options.
-* fno-optional-diags: C++ Dialect Options.
-* fno-peephole: Optimize Options.
-* fno-peephole2: Optimize Options.
-* fno-rtti: C++ Dialect Options.
-* fno-sched-interblock: Optimize Options.
-* fno-sched-spec: Optimize Options.
-* fno-show-column: Preprocessor Options.
-* fno-signed-bitfields: C Dialect Options.
-* fno-stack-limit: Code Gen Options.
-* fno-trapping-math: Optimize Options.
-* fno-unsigned-bitfields: C Dialect Options.
-* fno-weak: C++ Dialect Options.
-* fnon-call-exceptions: Code Gen Options.
-* fomit-frame-pointer: Optimize Options.
-* foptimize-register-move: Optimize Options.
-* foptimize-sibling-calls: Optimize Options.
-* fpack-struct: Code Gen Options.
-* fpcc-struct-return <1>: Incompatibilities.
-* fpcc-struct-return: Code Gen Options.
-* fpermissive: C++ Dialect Options.
-* fPIC: Code Gen Options.
-* fpic: Code Gen Options.
-* fprefetch-loop-arrays: Optimize Options.
-* fpreprocessed: Preprocessor Options.
-* fpretend-float: Debugging Options.
-* fprofile-arcs <1>: Other Builtins.
-* fprofile-arcs: Debugging Options.
-* freduce-all-givs: Optimize Options.
-* freg-struct-return: Code Gen Options.
-* fregmove: Optimize Options.
-* frename-registers: Optimize Options.
-* frepo <1>: Template Instantiation.
-* frepo: C++ Dialect Options.
-* frerun-cse-after-loop: Optimize Options.
-* frerun-loop-opt: Optimize Options.
-* fsched-spec-load: Optimize Options.
-* fsched-spec-load-dangerous: Optimize Options.
-* fsched-verbose: Debugging Options.
-* fschedule-insns: Optimize Options.
-* fschedule-insns2: Optimize Options.
-* fshared-data: Code Gen Options.
-* fshort-double: Code Gen Options.
-* fshort-enums <1>: Non-bugs.
-* fshort-enums <2>: Type Attributes.
-* fshort-enums: Code Gen Options.
-* fshort-wchar: Code Gen Options.
-* fsigned-bitfields <1>: Non-bugs.
-* fsigned-bitfields: C Dialect Options.
-* fsigned-char: C Dialect Options.
-* fsingle-precision-constant: Optimize Options.
-* fssa: Optimize Options.
-* fssa-ccp: Optimize Options.
-* fssa-dce: Optimize Options.
-* fstack-check: Code Gen Options.
-* fstack-limit-register: Code Gen Options.
-* fstack-limit-symbol: Code Gen Options.
-* fstats: C++ Dialect Options.
-* fstrength-reduce: Optimize Options.
-* fstrict-aliasing: Optimize Options.
-* fsyntax-only: Warning Options.
-* ftabstop: Preprocessor Options.
-* ftemplate-depth: C++ Dialect Options.
-* ftest-coverage: Debugging Options.
-* fthread-jumps: Optimize Options.
-* ftime-report: Debugging Options.
-* ftrapv: Optimize Options.
-* funroll-all-loops: Optimize Options.
-* funroll-loops <1>: Non-bugs.
-* funroll-loops: Optimize Options.
-* funsafe-math-optimizations: Optimize Options.
-* funsigned-bitfields <1>: Non-bugs.
-* funsigned-bitfields: C Dialect Options.
-* funsigned-char: C Dialect Options.
-* funwind-tables: Code Gen Options.
-* fuse-cxa-atexit: C++ Dialect Options.
-* fverbose-asm: Code Gen Options.
-* fvolatile: Code Gen Options.
-* fvolatile-global: Code Gen Options.
-* fvolatile-static: Code Gen Options.
-* fvtable-gc: C++ Dialect Options.
-* fwritable-strings <1>: Incompatibilities.
-* fwritable-strings: C Dialect Options.
-* G <1>: System V Options.
-* G <2>: MIPS Options.
-* G <3>: RS/6000 and PowerPC Options.
-* G: M32R/D Options.
-* g: Debugging Options.
-* gcc: Preprocessor Options.
-* gcoff: Debugging Options.
-* gdwarf: Debugging Options.
-* gdwarf+: Debugging Options.
-* gdwarf-2: Debugging Options.
-* gen-decls: Objective-C Dialect Options.
-* ggdb: Debugging Options.
-* gstabs: Debugging Options.
-* gstabs+: Debugging Options.
-* gvms: Debugging Options.
-* gxcoff: Debugging Options.
-* gxcoff+: Debugging Options.
-* H: Preprocessor Options.
-* h: Preprocessor Options.
-* help <1>: Preprocessor Options.
-* help: Overall Options.
-* I <1>: Directory Options.
-* I: Preprocessor Options.
-* I- <1>: Directory Options.
-* I-: Preprocessor Options.
-* idirafter: Preprocessor Options.
-* imacros: Preprocessor Options.
-* include: Preprocessor Options.
-* iprefix: Preprocessor Options.
-* isystem: Preprocessor Options.
-* iwithprefix: Preprocessor Options.
-* iwithprefixbefore: Preprocessor Options.
-* L: Directory Options.
-* l: Link Options.
-* lobjc: Link Options.
-* M: Preprocessor Options.
-* m1: SH Options.
-* m10: PDP-11 Options.
-* m128bit-long-double: i386 and x86-64 Options.
-* m16-bit: CRIS Options.
-* m2: SH Options.
-* m210: MCore Options.
-* m29000: AMD29K Options.
-* m29050: AMD29K Options.
-* m3: SH Options.
-* m31: S/390 and zSeries Options.
-* m32 <1>: i386 and x86-64 Options.
-* m32: SPARC Options.
-* m32-bit: CRIS Options.
-* m32032: NS32K Options.
-* m32081: NS32K Options.
-* m32332: NS32K Options.
-* m32381: NS32K Options.
-* m32532: NS32K Options.
-* m32r: M32R/D Options.
-* m32rx: M32R/D Options.
-* m340: MCore Options.
-* m386: i386 and x86-64 Options.
-* m3dnow: i386 and x86-64 Options.
-* m3e: SH Options.
-* m4: SH Options.
-* m4-nofpu: SH Options.
-* m4-single: SH Options.
-* m4-single-only: SH Options.
-* m40: PDP-11 Options.
-* m45: PDP-11 Options.
-* m4650: MIPS Options.
-* m486: i386 and x86-64 Options.
-* m4byte-functions: MCore Options.
-* m5200: M680x0 Options.
-* m64 <1>: S/390 and zSeries Options.
-* m64 <2>: i386 and x86-64 Options.
-* m64: SPARC Options.
-* m68000: M680x0 Options.
-* m68020: M680x0 Options.
-* m68020-40: M680x0 Options.
-* m68020-60: M680x0 Options.
-* m68030: M680x0 Options.
-* m68040: M680x0 Options.
-* m68060: M680x0 Options.
-* m6811: M68hc1x Options.
-* m6812: M68hc1x Options.
-* m68881: M680x0 Options.
-* m68hc11: M68hc1x Options.
-* m68hc12: M68hc1x Options.
-* m8-bit: CRIS Options.
-* m88000: M88K Options.
-* m88100: M88K Options.
-* m88110: M88K Options.
-* m96bit-long-double: i386 and x86-64 Options.
-* mabi-mmixware: MMIX Options.
-* mabi=32: MIPS Options.
-* mabi=64: MIPS Options.
-* mabi=altivec: RS/6000 and PowerPC Options.
-* mabi=eabi: MIPS Options.
-* mabi=gnu: MMIX Options.
-* mabi=n32: MIPS Options.
-* mabi=no-altivec: RS/6000 and PowerPC Options.
-* mabi=o64: MIPS Options.
-* mabicalls: MIPS Options.
-* mabort-on-noreturn: ARM Options.
-* mabshi: PDP-11 Options.
-* mac0: PDP-11 Options.
-* maccumulate-outgoing-args: i386 and x86-64 Options.
-* mads: RS/6000 and PowerPC Options.
-* maix-struct-return: RS/6000 and PowerPC Options.
-* maix32: RS/6000 and PowerPC Options.
-* maix64: RS/6000 and PowerPC Options.
-* malign-300: H8/300 Options.
-* malign-double: i386 and x86-64 Options.
-* malign-int: M680x0 Options.
-* malignment-traps: ARM Options.
-* malpha-as: DEC Alpha Options.
-* maltivec: RS/6000 and PowerPC Options.
-* mam33: MN10300 Options.
-* maout: CRIS Options.
-* mapcs: ARM Options.
-* mapcs-26: ARM Options.
-* mapcs-32: ARM Options.
-* mapcs-frame: ARM Options.
-* mapp-regs: SPARC Options.
-* march <1>: CRIS Options.
-* march <2>: HPPA Options.
-* march <3>: i386 and x86-64 Options.
-* march <4>: MIPS Options.
-* march: ARM Options.
-* margcount: Convex Options.
-* masm-compat: Intel 960 Options.
-* masm-optimize: D30V Options.
-* masm=DIALECT: i386 and x86-64 Options.
-* mauto-incdec: M68hc1x Options.
-* mauto-pic: IA-64 Options.
-* mb: SH Options.
-* mb-step: IA-64 Options.
-* mbackchain: S/390 and zSeries Options.
-* mbase-addresses: MMIX Options.
-* mbcopy: PDP-11 Options.
-* mbig <1>: TMS320C3x/C4x Options.
-* mbig: RS/6000 and PowerPC Options.
-* mbig-endian <1>: Xtensa Options.
-* mbig-endian <2>: IA-64 Options.
-* mbig-endian <3>: MCore Options.
-* mbig-endian <4>: RS/6000 and PowerPC Options.
-* mbig-endian: ARM Options.
-* mbig-memory: TMS320C3x/C4x Options.
-* mbig-pic: M88K Options.
-* mbig-switch <1>: V850 Options.
-* mbig-switch: HPPA Options.
-* mbigtable: SH Options.
-* mbit-align: RS/6000 and PowerPC Options.
-* mbitfield <1>: NS32K Options.
-* mbitfield: M680x0 Options.
-* mbk: TMS320C3x/C4x Options.
-* mbooleans: Xtensa Options.
-* mbranch-cheap: PDP-11 Options.
-* mbranch-cost: D30V Options.
-* mbranch-expensive: PDP-11 Options.
-* mbranch-predict: MMIX Options.
-* mbroken-saverestore: SPARC Options.
-* mbsd: ARM Options.
-* mbuild-constants: DEC Alpha Options.
-* mbw: AMD29K Options.
-* mbwx: DEC Alpha Options.
-* mc1: Convex Options.
-* mc2: Convex Options.
-* mc300: Clipper Options.
-* mc32: Convex Options.
-* mc34: Convex Options.
-* mc38: Convex Options.
-* mc400: Clipper Options.
-* mc68000: M680x0 Options.
-* mc68020: M680x0 Options.
-* mca: Intel 960 Options.
-* mcall-aix: RS/6000 and PowerPC Options.
-* mcall-gnu: RS/6000 and PowerPC Options.
-* mcall-lib-mul: RT Options.
-* mcall-linux: RS/6000 and PowerPC Options.
-* mcall-netbsd: RS/6000 and PowerPC Options.
-* mcall-prologues: AVR Options.
-* mcall-solaris: RS/6000 and PowerPC Options.
-* mcall-sysv: RS/6000 and PowerPC Options.
-* mcall-sysv-eabi: RS/6000 and PowerPC Options.
-* mcall-sysv-noeabi: RS/6000 and PowerPC Options.
-* mcallee-super-interworking: ARM Options.
-* mcaller-super-interworking: ARM Options.
-* mcallgraph-data: MCore Options.
-* mcc-init: CRIS Options.
-* mcf: Intel 960 Options.
-* mcheck-zero-division: M88K Options.
-* mcix: DEC Alpha Options.
-* mcmodel=embmedany: SPARC Options.
-* mcmodel=kernel: i386 and x86-64 Options.
-* mcmodel=large: i386 and x86-64 Options.
-* mcmodel=medany: SPARC Options.
-* mcmodel=medium: i386 and x86-64 Options.
-* mcmodel=medlow: SPARC Options.
-* mcmodel=medmid: SPARC Options.
-* mcmodel=small: i386 and x86-64 Options.
-* mcode-align: Intel 960 Options.
-* mcode-model=large: M32R/D Options.
-* mcode-model=medium: M32R/D Options.
-* mcode-model=small: M32R/D Options.
-* mcomplex-addr: Intel 960 Options.
-* mcond-exec: D30V Options.
-* mconst-align: CRIS Options.
-* mconstant-gp: IA-64 Options.
-* mcpu <1>: CRIS Options.
-* mcpu <2>: ARC Options.
-* mcpu <3>: TMS320C3x/C4x Options.
-* mcpu <4>: DEC Alpha Options.
-* mcpu <5>: i386 and x86-64 Options.
-* mcpu <6>: MIPS Options.
-* mcpu <7>: RS/6000 and PowerPC Options.
-* mcpu <8>: ARM Options.
-* mcpu: SPARC Options.
-* mcpu32: M680x0 Options.
-* mcypress: SPARC Options.
-* MD: Preprocessor Options.
-* mdalign: SH Options.
-* mdata: ARC Options.
-* mdata-align: CRIS Options.
-* mdb: TMS320C3x/C4x Options.
-* mdebug: S/390 and zSeries Options.
-* mdec-asm: PDP-11 Options.
-* mdensity: Xtensa Options.
-* mdisable-fpregs: HPPA Options.
-* mdisable-indexing: HPPA Options.
-* mdiv: MCore Options.
-* mdouble-float: MIPS Options.
-* mdp-isr-reload: TMS320C3x/C4x Options.
-* mdw: AMD29K Options.
-* mdwarf2-asm: IA-64 Options.
-* meabi: RS/6000 and PowerPC Options.
-* melf <1>: MMIX Options.
-* melf: CRIS Options.
-* melinux: CRIS Options.
-* melinux-stacksize: CRIS Options.
-* memb: RS/6000 and PowerPC Options.
-* membedded-data: MIPS Options.
-* membedded-pic: MIPS Options.
-* mentry: MIPS Options.
-* mep: V850 Options.
-* mepsilon: MMIX Options.
-* metrax100: CRIS Options.
-* metrax4: CRIS Options.
-* mexplicit-relocs: DEC Alpha Options.
-* mextmem: D30V Options.
-* mextmemory: D30V Options.
-* MF: Preprocessor Options.
-* mfast-fix: TMS320C3x/C4x Options.
-* mfast-indirect-calls: HPPA Options.
-* mfaster-structs: SPARC Options.
-* mfix: DEC Alpha Options.
-* mfix7000: MIPS Options.
-* mfixed-range: IA-64 Options.
-* mflat: SPARC Options.
-* mfloat-ieee: DEC Alpha Options.
-* mfloat-vax: DEC Alpha Options.
-* mfloat32: PDP-11 Options.
-* mfloat64: PDP-11 Options.
-* mflush-func: MIPS Options.
-* mfmovd: SH Options.
-* mfp: ARM Options.
-* mfp-arg-in-fpregs: RT Options.
-* mfp-arg-in-gregs: RT Options.
-* mfp-reg: DEC Alpha Options.
-* mfp-rounding-mode: DEC Alpha Options.
-* mfp-trap-mode: DEC Alpha Options.
-* mfp32: MIPS Options.
-* mfp64: MIPS Options.
-* mfpa: M680x0 Options.
-* mfpe: ARM Options.
-* mfpu <1>: PDP-11 Options.
-* mfpu: SPARC Options.
-* mfull-fp-blocks: RT Options.
-* mfull-toc: RS/6000 and PowerPC Options.
-* mfused-madd <1>: Xtensa Options.
-* mfused-madd <2>: MIPS Options.
-* mfused-madd: RS/6000 and PowerPC Options.
-* mg: VAX Options.
-* MG: Preprocessor Options.
-* mgas <1>: DEC Alpha Options.
-* mgas <2>: HPPA Options.
-* mgas: MIPS Options.
-* mgnu: VAX Options.
-* mgnu-as: IA-64 Options.
-* mgnu-ld: IA-64 Options.
-* mgotplt: CRIS Options.
-* mgp32: MIPS Options.
-* mgp64: MIPS Options.
-* mgpopt: MIPS Options.
-* mh: H8/300 Options.
-* mhalf-pic: MIPS Options.
-* mhandle-large-shift: M88K Options.
-* mhard-float <1>: Xtensa Options.
-* mhard-float <2>: S/390 and zSeries Options.
-* mhard-float <3>: MIPS Options.
-* mhard-float <4>: RS/6000 and PowerPC Options.
-* mhard-float <5>: ARM Options.
-* mhard-float: SPARC Options.
-* mhard-quad-float: SPARC Options.
-* mhardlit: MCore Options.
-* mhc-struct-return <1>: Interoperation.
-* mhc-struct-return: RT Options.
-* mhimem: NS32K Options.
-* mhitachi: SH Options.
-* mic-compat: Intel 960 Options.
-* mic2.0-compat: Intel 960 Options.
-* mic3.0-compat: Intel 960 Options.
-* midentify-revision: M88K Options.
-* mieee <1>: SH Options.
-* mieee: DEC Alpha Options.
-* mieee-conformant: DEC Alpha Options.
-* mieee-fp: i386 and x86-64 Options.
-* mieee-with-inexact: DEC Alpha Options.
-* mimpure-text: AMD29K Options.
-* min-line-mul: RT Options.
-* minit-stack: AVR Options.
-* minline-all-stringops: i386 and x86-64 Options.
-* minline-divide-max-throughput: IA-64 Options.
-* minline-divide-min-latency: IA-64 Options.
-* mint16: PDP-11 Options.
-* mint32 <1>: PDP-11 Options.
-* mint32: H8/300 Options.
-* mint64: MIPS Options.
-* mintel-asm: Intel 960 Options.
-* mips1: MIPS Options.
-* mips16: MIPS Options.
-* mips2: MIPS Options.
-* mips3: MIPS Options.
-* mips4: MIPS Options.
-* misize: SH Options.
-* mjump-in-delay: HPPA Options.
-* mka: Intel 960 Options.
-* mkb: Intel 960 Options.
-* mkernel-registers: AMD29K Options.
-* mknuthdiv: MMIX Options.
-* ml: SH Options.
-* mlarge: AMD29K Options.
-* mlarge-data: DEC Alpha Options.
-* mleaf-procedures: Intel 960 Options.
-* mlibfuncs: MMIX Options.
-* mlinker-opt: HPPA Options.
-* mlinux: CRIS Options.
-* mlittle: RS/6000 and PowerPC Options.
-* mlittle-endian <1>: Xtensa Options.
-* mlittle-endian <2>: IA-64 Options.
-* mlittle-endian <3>: MCore Options.
-* mlittle-endian <4>: RS/6000 and PowerPC Options.
-* mlittle-endian <5>: ARM Options.
-* mlittle-endian: SPARC Options.
-* mlive-g0: SPARC Options.
-* mlong-calls <1>: V850 Options.
-* mlong-calls <2>: MIPS Options.
-* mlong-calls: ARM Options.
-* mlong-double-64: Intel 960 Options.
-* mlong-load-store: HPPA Options.
-* mlong32 <1>: MIPS Options.
-* mlong32: Convex Options.
-* mlong64 <1>: MIPS Options.
-* mlong64: Convex Options.
-* mlongcalls: Xtensa Options.
-* mloop-unsigned: TMS320C3x/C4x Options.
-* MM: Preprocessor Options.
-* mmac16: Xtensa Options.
-* mmad: MIPS Options.
-* mmangle-cpu: ARC Options.
-* mmax: DEC Alpha Options.
-* mmax-stack-frame: CRIS Options.
-* mmc: Intel 960 Options.
-* mmcu: AVR Options.
-* MMD: Preprocessor Options.
-* mmemcpy: MIPS Options.
-* mmemory-latency: DEC Alpha Options.
-* mmemparm: TMS320C3x/C4x Options.
-* mminimal-toc: RS/6000 and PowerPC Options.
-* mminimum-fp-blocks: RT Options.
-* mminmax: Xtensa Options.
-* mmips-as: MIPS Options.
-* mmips-tfile: MIPS Options.
-* mmmx: i386 and x86-64 Options.
-* mmpyi: TMS320C3x/C4x Options.
-* mmul16: Xtensa Options.
-* mmul32: Xtensa Options.
-* mmult-bug: MN10300 Options.
-* mmulti-add: NS32K Options.
-* mmultiple: RS/6000 and PowerPC Options.
-* mmvcle: S/390 and zSeries Options.
-* mmvme: RS/6000 and PowerPC Options.
-* mnbw: AMD29K Options.
-* mndw: AMD29K Options.
-* mnew-mnemonics: RS/6000 and PowerPC Options.
-* mno-3dnow: i386 and x86-64 Options.
-* mno-4byte-functions: MCore Options.
-* mno-abicalls: MIPS Options.
-* mno-abshi: PDP-11 Options.
-* mno-ac0: PDP-11 Options.
-* mno-align-double: i386 and x86-64 Options.
-* mno-align-int: M680x0 Options.
-* mno-align-stringops: i386 and x86-64 Options.
-* mno-alignment-traps: ARM Options.
-* mno-altivec: RS/6000 and PowerPC Options.
-* mno-am33: MN10300 Options.
-* mno-app-regs: SPARC Options.
-* mno-asm-optimize: D30V Options.
-* mno-backchain: S/390 and zSeries Options.
-* mno-base-addresses: MMIX Options.
-* mno-bit-align: RS/6000 and PowerPC Options.
-* mno-bk: TMS320C3x/C4x Options.
-* mno-booleans: Xtensa Options.
-* mno-branch-predict: MMIX Options.
-* mno-bwx: DEC Alpha Options.
-* mno-callgraph-data: MCore Options.
-* mno-check-zero-division: M88K Options.
-* mno-cix: DEC Alpha Options.
-* mno-code-align: Intel 960 Options.
-* mno-complex-addr: Intel 960 Options.
-* mno-const-align: CRIS Options.
-* mno-crt0: MN10300 Options.
-* mno-data-align: CRIS Options.
-* mno-db: TMS320C3x/C4x Options.
-* mno-debug: S/390 and zSeries Options.
-* mno-density: Xtensa Options.
-* mno-div: MCore Options.
-* mno-dwarf2-asm: IA-64 Options.
-* mno-eabi: RS/6000 and PowerPC Options.
-* mno-embedded-data: MIPS Options.
-* mno-embedded-pic: MIPS Options.
-* mno-ep: V850 Options.
-* mno-epsilon: MMIX Options.
-* mno-explicit-relocs: DEC Alpha Options.
-* mno-fancy-math-387: i386 and x86-64 Options.
-* mno-fast-fix: TMS320C3x/C4x Options.
-* mno-faster-structs: SPARC Options.
-* mno-fix: DEC Alpha Options.
-* mno-flat: SPARC Options.
-* mno-float32: PDP-11 Options.
-* mno-float64: PDP-11 Options.
-* mno-fp-in-toc: RS/6000 and PowerPC Options.
-* mno-fp-regs: DEC Alpha Options.
-* mno-fp-ret-in-387: i386 and x86-64 Options.
-* mno-fpu: SPARC Options.
-* mno-fused-madd <1>: Xtensa Options.
-* mno-fused-madd <2>: MIPS Options.
-* mno-fused-madd: RS/6000 and PowerPC Options.
-* mno-gnu-as: IA-64 Options.
-* mno-gnu-ld: IA-64 Options.
-* mno-gotplt: CRIS Options.
-* mno-gpopt: MIPS Options.
-* mno-half-pic: MIPS Options.
-* mno-hardlit: MCore Options.
-* mno-ieee-fp: i386 and x86-64 Options.
-* mno-impure-text: AMD29K Options.
-* mno-int16: PDP-11 Options.
-* mno-int32: PDP-11 Options.
-* mno-interrupts: AVR Options.
-* mno-knuthdiv: MMIX Options.
-* mno-leaf-procedures: Intel 960 Options.
-* mno-libfuncs: MMIX Options.
-* mno-long-calls <1>: V850 Options.
-* mno-long-calls <2>: MIPS Options.
-* mno-long-calls: ARM Options.
-* mno-longcalls: Xtensa Options.
-* mno-loop-unsigned: TMS320C3x/C4x Options.
-* mno-mac16: Xtensa Options.
-* mno-mad: MIPS Options.
-* mno-max: DEC Alpha Options.
-* mno-memcpy: MIPS Options.
-* mno-minmax: Xtensa Options.
-* mno-mips-tfile: MIPS Options.
-* mno-mips16: MIPS Options.
-* mno-mmx: i386 and x86-64 Options.
-* mno-mpyi: TMS320C3x/C4x Options.
-* mno-mul16: Xtensa Options.
-* mno-mul32: Xtensa Options.
-* mno-mult-bug: MN10300 Options.
-* mno-multiple: RS/6000 and PowerPC Options.
-* mno-multm: AMD29K Options.
-* mno-mvcle: S/390 and zSeries Options.
-* mno-nsa: Xtensa Options.
-* mno-ocs-debug-info: M88K Options.
-* mno-ocs-frame-position: M88K Options.
-* mno-optimize-arg-area: M88K Options.
-* mno-parallel-insns: TMS320C3x/C4x Options.
-* mno-parallel-mpy: TMS320C3x/C4x Options.
-* mno-pic: IA-64 Options.
-* mno-power: RS/6000 and PowerPC Options.
-* mno-power2: RS/6000 and PowerPC Options.
-* mno-powerpc: RS/6000 and PowerPC Options.
-* mno-powerpc-gfxopt: RS/6000 and PowerPC Options.
-* mno-powerpc-gpopt: RS/6000 and PowerPC Options.
-* mno-powerpc64: RS/6000 and PowerPC Options.
-* mno-prolog-function: V850 Options.
-* mno-prologue-epilogue: CRIS Options.
-* mno-prototype: RS/6000 and PowerPC Options.
-* mno-push-args: i386 and x86-64 Options.
-* mno-register-names: IA-64 Options.
-* mno-regnames: RS/6000 and PowerPC Options.
-* mno-relax-immediate: MCore Options.
-* mno-relocatable: RS/6000 and PowerPC Options.
-* mno-relocatable-lib: RS/6000 and PowerPC Options.
-* mno-reuse-arg-regs: AMD29K Options.
-* mno-rnames: MIPS Options.
-* mno-rptb: TMS320C3x/C4x Options.
-* mno-rpts: TMS320C3x/C4x Options.
-* mno-sched-prolog: ARM Options.
-* mno-sdata <1>: IA-64 Options.
-* mno-sdata: RS/6000 and PowerPC Options.
-* mno-serialize-volatile <1>: Interoperation.
-* mno-serialize-volatile <2>: Xtensa Options.
-* mno-serialize-volatile: M88K Options.
-* mno-sext: Xtensa Options.
-* mno-short-load-bytes: ARM Options.
-* mno-short-load-words: ARM Options.
-* mno-side-effects: CRIS Options.
-* mno-slow-bytes: MCore Options.
-* mno-small-exec: S/390 and zSeries Options.
-* mno-soft-float: DEC Alpha Options.
-* mno-space-regs: HPPA Options.
-* mno-split: PDP-11 Options.
-* mno-split-addresses: MIPS Options.
-* mno-sse: i386 and x86-64 Options.
-* mno-stack-align: CRIS Options.
-* mno-stack-bias: SPARC Options.
-* mno-stack-check: AMD29K Options.
-* mno-stats: MIPS Options.
-* mno-storem-bug: AMD29K Options.
-* mno-strict-align <1>: Intel 960 Options.
-* mno-strict-align <2>: RS/6000 and PowerPC Options.
-* mno-strict-align: M680x0 Options.
-* mno-string: RS/6000 and PowerPC Options.
-* mno-sum-in-toc: RS/6000 and PowerPC Options.
-* mno-svr3-shlib: i386 and x86-64 Options.
-* mno-symrename: ARM Options.
-* mno-tablejump: AVR Options.
-* mno-tail-call: Intel 960 Options.
-* mno-target-align: Xtensa Options.
-* mno-text-section-literals: Xtensa Options.
-* mno-toc: RS/6000 and PowerPC Options.
-* mno-toplevel-symbols: MMIX Options.
-* mno-unaligned-doubles: SPARC Options.
-* mno-underscores: M88K Options.
-* mno-uninit-const-in-rodata: MIPS Options.
-* mno-update: RS/6000 and PowerPC Options.
-* mno-volatile-asm-stop: IA-64 Options.
-* mno-wide-bitfields: MCore Options.
-* mno-xl-call: RS/6000 and PowerPC Options.
-* mno-zero-extend: MMIX Options.
-* mnoargcount: Convex Options.
-* mnobitfield <1>: NS32K Options.
-* mnobitfield: M680x0 Options.
-* mnohc-struct-return: RT Options.
-* mnohimem: NS32K Options.
-* mnomacsave: SH Options.
-* mnomulti-add: NS32K Options.
-* mnop-fun-dllimport: ARM Options.
-* mnoregparam: NS32K Options.
-* mnormal: AMD29K Options.
-* mnosb: NS32K Options.
-* mnsa: Xtensa Options.
-* mnumerics: Intel 960 Options.
-* mocs-debug-info: M88K Options.
-* mocs-frame-position: M88K Options.
-* mold-align: Intel 960 Options.
-* mold-mnemonics: RS/6000 and PowerPC Options.
-* momit-leaf-frame-pointer: i386 and x86-64 Options.
-* monchip: D30V Options.
-* moptimize-arg-area: M88K Options.
-* MP: Preprocessor Options.
-* mpa-risc-1-0: HPPA Options.
-* mpa-risc-1-1: HPPA Options.
-* mpa-risc-2-0: HPPA Options.
-* mpadstruct: SH Options.
-* mparallel-insns: TMS320C3x/C4x Options.
-* mparallel-mpy: TMS320C3x/C4x Options.
-* mparanoid: TMS320C3x/C4x Options.
-* mpcrel: M680x0 Options.
-* mpdebug: CRIS Options.
-* mpe: RS/6000 and PowerPC Options.
-* mpentium: i386 and x86-64 Options.
-* mpentiumpro: i386 and x86-64 Options.
-* mpic-register: ARM Options.
-* mpoke-function-name: ARM Options.
-* mportable-runtime: HPPA Options.
-* mpower: RS/6000 and PowerPC Options.
-* mpower2: RS/6000 and PowerPC Options.
-* mpowerpc: RS/6000 and PowerPC Options.
-* mpowerpc-gfxopt: RS/6000 and PowerPC Options.
-* mpowerpc-gpopt: RS/6000 and PowerPC Options.
-* mpowerpc64: RS/6000 and PowerPC Options.
-* mprefergot: SH Options.
-* mpreferred-stack-boundary: i386 and x86-64 Options.
-* mprolog-function: V850 Options.
-* mprologue-epilogue: CRIS Options.
-* mprototype: RS/6000 and PowerPC Options.
-* mpush-args: i386 and x86-64 Options.
-* MQ: Preprocessor Options.
-* mregister-names: IA-64 Options.
-* mregnames: RS/6000 and PowerPC Options.
-* mregparam: NS32K Options.
-* mregparm <1>: TMS320C3x/C4x Options.
-* mregparm: i386 and x86-64 Options.
-* mrelax <1>: SH Options.
-* mrelax <2>: H8/300 Options.
-* mrelax <3>: MN10300 Options.
-* mrelax: MN10200 Options.
-* mrelax-immediate: MCore Options.
-* mrelocatable: RS/6000 and PowerPC Options.
-* mrelocatable-lib: RS/6000 and PowerPC Options.
-* mreuse-arg-regs: AMD29K Options.
-* mrnames: MIPS Options.
-* mrodata: ARC Options.
-* mrptb: TMS320C3x/C4x Options.
-* mrpts: TMS320C3x/C4x Options.
-* mrtd <1>: Function Attributes.
-* mrtd <2>: NS32K Options.
-* mrtd <3>: i386 and x86-64 Options.
-* mrtd: M680x0 Options.
-* ms: H8/300 Options.
-* ms2600: H8/300 Options.
-* msa: Intel 960 Options.
-* msb <1>: NS32K Options.
-* msb: Intel 960 Options.
-* mschedule: HPPA Options.
-* msda: V850 Options.
-* msdata <1>: IA-64 Options.
-* msdata: RS/6000 and PowerPC Options.
-* msdata-data: RS/6000 and PowerPC Options.
-* msdata=default: RS/6000 and PowerPC Options.
-* msdata=eabi: RS/6000 and PowerPC Options.
-* msdata=none <1>: RS/6000 and PowerPC Options.
-* msdata=none: M32R/D Options.
-* msdata=sdata: M32R/D Options.
-* msdata=sysv: RS/6000 and PowerPC Options.
-* msdata=use: M32R/D Options.
-* mserialize-volatile <1>: Xtensa Options.
-* mserialize-volatile: M88K Options.
-* msext: Xtensa Options.
-* mshort <1>: M68hc1x Options.
-* mshort: M680x0 Options.
-* mshort-data: M88K Options.
-* mshort-load-bytes: ARM Options.
-* mshort-load-words: ARM Options.
-* msim <1>: Xstormy16 Options.
-* msim: RS/6000 and PowerPC Options.
-* msingle-float: MIPS Options.
-* msingle-pic-base: ARM Options.
-* msize: AVR Options.
-* mslow-bytes: MCore Options.
-* msmall <1>: TMS320C3x/C4x Options.
-* msmall: AMD29K Options.
-* msmall-data: DEC Alpha Options.
-* msmall-exec: S/390 and zSeries Options.
-* msmall-memory: TMS320C3x/C4x Options.
-* msoft-float <1>: Xtensa Options.
-* msoft-float <2>: PDP-11 Options.
-* msoft-float <3>: S/390 and zSeries Options.
-* msoft-float <4>: NS32K Options.
-* msoft-float <5>: DEC Alpha Options.
-* msoft-float <6>: Intel 960 Options.
-* msoft-float <7>: HPPA Options.
-* msoft-float <8>: i386 and x86-64 Options.
-* msoft-float <9>: MIPS Options.
-* msoft-float <10>: RS/6000 and PowerPC Options.
-* msoft-float <11>: ARM Options.
-* msoft-float <12>: AMD29K Options.
-* msoft-float <13>: SPARC Options.
-* msoft-float: M680x0 Options.
-* msoft-quad-float: SPARC Options.
-* msoft-reg-count: M68hc1x Options.
-* mspace <1>: V850 Options.
-* mspace: SH Options.
-* msparclite: SPARC Options.
-* msplit: PDP-11 Options.
-* msplit-addresses: MIPS Options.
-* msse: i386 and x86-64 Options.
-* mstack-align: CRIS Options.
-* mstack-bias: SPARC Options.
-* mstack-check: AMD29K Options.
-* mstats: MIPS Options.
-* mstorem-bug: AMD29K Options.
-* mstrict-align <1>: Intel 960 Options.
-* mstrict-align <2>: RS/6000 and PowerPC Options.
-* mstrict-align: M680x0 Options.
-* mstring: RS/6000 and PowerPC Options.
-* mstructure-size-boundary: ARM Options.
-* msupersparc: SPARC Options.
-* msvr3: M88K Options.
-* msvr3-shlib: i386 and x86-64 Options.
-* msvr4: M88K Options.
-* msvr4-struct-return: RS/6000 and PowerPC Options.
-* MT: Preprocessor Options.
-* mtail-call: Intel 960 Options.
-* mtarget-align: Xtensa Options.
-* mtda: V850 Options.
-* mtext: ARC Options.
-* mtext-section-literals: Xtensa Options.
-* mthreads: i386 and x86-64 Options.
-* mthumb: ARM Options.
-* mthumb-interwork: ARM Options.
-* mti: TMS320C3x/C4x Options.
-* mtiny-stack: AVR Options.
-* mtoc: RS/6000 and PowerPC Options.
-* mtoplevel-symbols: MMIX Options.
-* mtpcs-frame: ARM Options.
-* mtpcs-leaf-frame: ARM Options.
-* mtrap-large-shift: M88K Options.
-* mtrap-precision: DEC Alpha Options.
-* mtune <1>: CRIS Options.
-* mtune <2>: DEC Alpha Options.
-* mtune <3>: MIPS Options.
-* mtune <4>: RS/6000 and PowerPC Options.
-* mtune <5>: ARM Options.
-* mtune: SPARC Options.
-* munaligned-doubles: SPARC Options.
-* muninit-const-in-rodata: MIPS Options.
-* munix: VAX Options.
-* munix-asm: PDP-11 Options.
-* mupdate: RS/6000 and PowerPC Options.
-* muse-div-instruction: M88K Options.
-* muser-registers: AMD29K Options.
-* musermode: SH Options.
-* mv8: SPARC Options.
-* mv850: V850 Options.
-* mversion-03.00: M88K Options.
-* mvms-return-codes: DEC Alpha/VMS Options.
-* mvolatile-asm-stop: IA-64 Options.
-* mvolatile-cache: Convex Options.
-* mvolatile-nocache: Convex Options.
-* mvxworks: RS/6000 and PowerPC Options.
-* mwarn-passed-structs: M88K Options.
-* mwide-bitfields: MCore Options.
-* mwords-little-endian: ARM Options.
-* mxl-call: RS/6000 and PowerPC Options.
-* mxopen: ARM Options.
-* myellowknife: RS/6000 and PowerPC Options.
-* mzda: V850 Options.
-* mzero-extend: MMIX Options.
-* no-crt0: MIPS Options.
-* no-integrated-cpp: C Dialect Options.
-* no-red-zone: i386 and x86-64 Options.
-* noasmopt: Interoperation.
-* nocpp: MIPS Options.
-* nodefaultlibs: Link Options.
-* nostartfiles: Link Options.
-* nostdinc: Preprocessor Options.
-* nostdinc++ <1>: Preprocessor Options.
-* nostdinc++: C++ Dialect Options.
-* nostdlib: Link Options.
-* o: Preprocessor Options.
-* O: Optimize Options.
-* o: Overall Options.
-* O0: Optimize Options.
-* O1: Optimize Options.
-* O2: Optimize Options.
-* O3: Optimize Options.
-* Os: Optimize Options.
-* P: Preprocessor Options.
-* p: Debugging Options.
-* param: Optimize Options.
-* pass-exit-codes: Overall Options.
-* pedantic <1>: Warnings and Errors.
-* pedantic <2>: Alternate Keywords.
-* pedantic <3>: C Extensions.
-* pedantic <4>: Preprocessor Options.
-* pedantic <5>: Warning Options.
-* pedantic: Standards.
-* pedantic-errors <1>: Warnings and Errors.
-* pedantic-errors <2>: Non-bugs.
-* pedantic-errors <3>: Actual Bugs.
-* pedantic-errors <4>: Preprocessor Options.
-* pedantic-errors <5>: Warning Options.
-* pedantic-errors: Standards.
-* pg: Debugging Options.
-* pipe: Overall Options.
-* print-file-name: Debugging Options.
-* print-libgcc-file-name: Debugging Options.
-* print-multi-directory: Debugging Options.
-* print-multi-lib: Debugging Options.
-* print-prog-name: Debugging Options.
-* print-search-dirs: Debugging Options.
-* pthread: RS/6000 and PowerPC Options.
-* Q: Debugging Options.
-* Qn: System V Options.
-* Qy: System V Options.
-* remap: Preprocessor Options.
-* s: Link Options.
-* S <1>: Link Options.
-* S: Overall Options.
-* save-temps: Debugging Options.
-* shared: Link Options.
-* shared-libgcc: Link Options.
-* sim: CRIS Options.
-* sim2: CRIS Options.
-* specs: Directory Options.
-* static: Link Options.
-* static-libgcc: Link Options.
-* std <1>: Non-bugs.
-* std <2>: Other Builtins.
-* std <3>: C Dialect Options.
-* std: Standards.
-* std=: Preprocessor Options.
-* symbolic: Link Options.
-* target-help <1>: Preprocessor Options.
-* target-help: Overall Options.
-* time: Debugging Options.
-* traditional <1>: Non-bugs.
-* traditional <2>: Incompatibilities.
-* traditional <3>: Preprocessor Options.
-* traditional <4>: C Dialect Options.
-* traditional: Standards.
-* traditional-cpp: C Dialect Options.
-* trigraphs <1>: Preprocessor Options.
-* trigraphs: C Dialect Options.
-* u: Link Options.
-* U: Preprocessor Options.
-* undef: Preprocessor Options.
-* V: Target Options.
-* v <1>: Preprocessor Options.
-* v: Overall Options.
-* version <1>: Preprocessor Options.
-* version: Overall Options.
-* W: Incompatibilities.
-* w: Preprocessor Options.
-* W: Warning Options.
-* w: Warning Options.
-* Wa: Assembler Options.
-* Wabi: C++ Dialect Options.
-* Waggregate-return: Warning Options.
-* Wall <1>: Standard Libraries.
-* Wall <2>: Preprocessor Options.
-* Wall: Warning Options.
-* Wbad-function-cast: Warning Options.
-* Wcast-align: Warning Options.
-* Wcast-qual: Warning Options.
-* Wchar-subscripts: Warning Options.
-* Wcomment <1>: Preprocessor Options.
-* Wcomment: Warning Options.
-* Wcomments: Preprocessor Options.
-* Wconversion <1>: Protoize Caveats.
-* Wconversion: Warning Options.
-* Wctor-dtor-privacy: C++ Dialect Options.
-* Wdisabled-optimization: Warning Options.
-* Wdiv-by-zero: Warning Options.
-* Weffc++: C++ Dialect Options.
-* Werror <1>: Preprocessor Options.
-* Werror: Warning Options.
-* Werror-implicit-function-declaration: Warning Options.
-* Wfloat-equal: Warning Options.
-* Wformat <1>: Function Attributes.
-* Wformat: Warning Options.
-* Wformat-nonliteral <1>: Function Attributes.
-* Wformat-nonliteral: Warning Options.
-* Wformat-security: Warning Options.
-* Wformat=2: Warning Options.
-* Wimplicit: Warning Options.
-* Wimplicit-function-declaration: Warning Options.
-* Wimplicit-int: Warning Options.
-* Wimport: Preprocessor Options.
-* Winline <1>: Inline.
-* Winline: Warning Options.
-* Wl: Link Options.
-* Wlarger-than: Warning Options.
-* Wlong-long: Warning Options.
-* Wmain: Warning Options.
-* Wmissing-braces: Warning Options.
-* Wmissing-declarations: Warning Options.
-* Wmissing-format-attribute: Warning Options.
-* Wmissing-noreturn: Warning Options.
-* Wmissing-prototypes: Warning Options.
-* Wmultichar: Warning Options.
-* Wnested-externs: Warning Options.
-* Wno-deprecated: C++ Dialect Options.
-* Wno-deprecated-declarations: Warning Options.
-* Wno-div-by-zero: Warning Options.
-* Wno-format-extra-args: Warning Options.
-* Wno-format-y2k: Warning Options.
-* Wno-import: Warning Options.
-* Wno-long-long: Warning Options.
-* Wno-multichar: Warning Options.
-* Wno-non-template-friend: C++ Dialect Options.
-* Wno-pmf-conversions <1>: Bound member functions.
-* Wno-pmf-conversions: C++ Dialect Options.
-* Wno-protocol: Objective-C Dialect Options.
-* Wnon-virtual-dtor: C++ Dialect Options.
-* Wold-style-cast: C++ Dialect Options.
-* Woverloaded-virtual: C++ Dialect Options.
-* Wp: Preprocessor Options.
-* Wpacked: Warning Options.
-* Wpadded: Warning Options.
-* Wparentheses: Warning Options.
-* Wpointer-arith <1>: Pointer Arith.
-* Wpointer-arith: Warning Options.
-* Wredundant-decls: Warning Options.
-* Wreorder <1>: Warning Options.
-* Wreorder: C++ Dialect Options.
-* Wreturn-type: Warning Options.
-* Wselector: Objective-C Dialect Options.
-* Wsequence-point: Warning Options.
-* Wshadow: Warning Options.
-* Wsign-compare: Warning Options.
-* Wsign-promo: C++ Dialect Options.
-* Wstrict-prototypes: Warning Options.
-* Wswitch: Warning Options.
-* Wsynth: C++ Dialect Options.
-* Wsystem-headers <1>: Preprocessor Options.
-* Wsystem-headers: Warning Options.
-* Wtraditional <1>: Preprocessor Options.
-* Wtraditional: Warning Options.
-* Wtrigraphs <1>: Preprocessor Options.
-* Wtrigraphs: Warning Options.
-* Wundef <1>: Preprocessor Options.
-* Wundef: Warning Options.
-* Wuninitialized: Warning Options.
-* Wunknown-pragmas: Warning Options.
-* Wunreachable-code: Warning Options.
-* Wunused: Warning Options.
-* Wunused-function: Warning Options.
-* Wunused-label: Warning Options.
-* Wunused-parameter: Warning Options.
-* Wunused-value: Warning Options.
-* Wunused-variable: Warning Options.
-* Wwrite-strings: Warning Options.
-* x <1>: Preprocessor Options.
-* x: Overall Options.
-* Xlinker: Link Options.
-* Ym: System V Options.
-* YP: System V Options.
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Index, Prev: Option Index, Up: Top
-
-Index
-*****
-
-* Menu:
-
-* ! in constraint: Multi-Alternative.
-* # in constraint: Modifiers.
-* #pragma: Pragmas.
-* #pragma implementation: C++ Interface.
-* #pragma implementation, implied: C++ Interface.
-* #pragma interface: C++ Interface.
-* #pragma, reason for not using: Function Attributes.
-* $: Dollar Signs.
-* % in constraint: Modifiers.
-* %include: Spec Files.
-* %include_noerr: Spec Files.
-* %rename: Spec Files.
-* & in constraint: Modifiers.
-* ': Incompatibilities.
-* * in constraint: Modifiers.
-* + in constraint: Modifiers.
-* -lgcc, use with -nodefaultlibs: Link Options.
-* -lgcc, use with -nostdlib: Link Options.
-* -nodefaultlibs and unresolved references: Link Options.
-* -nostdlib and unresolved references: Link Options.
-* .sdata/.sdata2 references (PowerPC): RS/6000 and PowerPC Options.
-* //: C++ Comments.
-* 0 in constraint: Simple Constraints.
-* < in constraint: Simple Constraints.
-* <?: Min and Max.
-* = in constraint: Modifiers.
-* > in constraint: Simple Constraints.
-* >?: Min and Max.
-* ? in constraint: Multi-Alternative.
-* ?: extensions <1>: Conditionals.
-* ?: extensions: Lvalues.
-* ?: side effect: Conditionals.
-* \a: C Dialect Options.
-* \x: C Dialect Options.
-* _ in variables in macros: Typeof.
-* __builtin_apply: Constructing Calls.
-* __builtin_apply_args: Constructing Calls.
-* __builtin_choose_expr: Other Builtins.
-* __builtin_constant_p: Other Builtins.
-* __builtin_expect: Other Builtins.
-* __builtin_frame_address: Return Address.
-* __builtin_isgreater: Other Builtins.
-* __builtin_isgreaterequal: Other Builtins.
-* __builtin_isless: Other Builtins.
-* __builtin_islessequal: Other Builtins.
-* __builtin_islessgreater: Other Builtins.
-* __builtin_isunordered: Other Builtins.
-* __builtin_prefetch: Other Builtins.
-* __builtin_return: Constructing Calls.
-* __builtin_return_address: Return Address.
-* __builtin_types_compatible_p: Other Builtins.
-* __complex__ keyword: Complex.
-* __extension__: Alternate Keywords.
-* __func__ identifier: Function Names.
-* __FUNCTION__ identifier: Function Names.
-* __imag__ keyword: Complex.
-* __PRETTY_FUNCTION__ identifier: Function Names.
-* __real__ keyword: Complex.
-* __STDC_HOSTED__: Standards.
-* _Complex keyword: Complex.
-* _Exit: Other Builtins.
-* _exit: Other Builtins.
-* ABI: Compatibility.
-* abort: Other Builtins.
-* abs: Other Builtins.
-* accessing volatiles: Volatiles.
-* Ada: G++ and GCC.
-* address constraints: Simple Constraints.
-* address of a label: Labels as Values.
-* address_operand: Simple Constraints.
-* alias attribute: Function Attributes.
-* aliasing of parameters: Code Gen Options.
-* aligned attribute <1>: Type Attributes.
-* aligned attribute: Variable Attributes.
-* alignment: Alignment.
-* Alliant: Interoperation.
-* alloca: Other Builtins.
-* alloca vs variable-length arrays: Variable Length.
-* alternate keywords: Alternate Keywords.
-* always_inline function attribute: Function Attributes.
-* AMD x86-64 Options: i386 and x86-64 Options.
-* AMD1: Standards.
-* AMD29K options: AMD29K Options.
-* ANSI C: Standards.
-* ANSI C standard: Standards.
-* ANSI C89: Standards.
-* ANSI support: C Dialect Options.
-* ANSI X3.159-1989: Standards.
-* apostrophes: Incompatibilities.
-* application binary interface: Compatibility.
-* ARC Options: ARC Options.
-* arguments in frame (88k): M88K Options.
-* ARM [Annotated C++ Reference Manual]: Backwards Compatibility.
-* ARM options: ARM Options.
-* arrays of length zero: Zero Length.
-* arrays of variable length: Variable Length.
-* arrays, non-lvalue: Subscripting.
-* asm constraints: Constraints.
-* asm expressions: Extended Asm.
-* assembler instructions: Extended Asm.
-* assembler names for identifiers: Asm Labels.
-* assembler syntax, 88k: M88K Options.
-* assembly code, invalid: Bug Criteria.
-* attribute of types: Type Attributes.
-* attribute of variables: Variable Attributes.
-* attribute syntax: Attribute Syntax.
-* autoincrement/decrement addressing: Simple Constraints.
-* automatic inline for C++ member fns: Inline.
-* AVR Options: AVR Options.
-* backtrace for bug reports: Bug Reporting.
-* Backwards Compatibility: Backwards Compatibility.
-* bcmp: Other Builtins.
-* binary compatibility: Compatibility.
-* bit shift overflow (88k): M88K Options.
-* bound pointer to member function: Bound member functions.
-* bug criteria: Bug Criteria.
-* bug report mailing lists: Bug Lists.
-* bugs: Bugs.
-* bugs, known: Trouble.
-* built-in functions <1>: Other Builtins.
-* built-in functions: C Dialect Options.
-* byte writes (29k): AMD29K Options.
-* bzero: Other Builtins.
-* C compilation options: Invoking GCC.
-* C intermediate output, nonexistent: G++ and GCC.
-* C language extensions: C Extensions.
-* C language, traditional: C Dialect Options.
-* C standard: Standards.
-* C standards: Standards.
-* c++: Invoking G++.
-* C++: G++ and GCC.
-* C++ comments: C++ Comments.
-* C++ compilation options: Invoking GCC.
-* C++ interface and implementation headers: C++ Interface.
-* C++ language extensions: C++ Extensions.
-* C++ member fns, automatically inline: Inline.
-* C++ misunderstandings: C++ Misunderstandings.
-* C++ options, command line: C++ Dialect Options.
-* C++ pragmas, effect on inlining: C++ Interface.
-* C++ source file suffixes: Invoking G++.
-* C++ static data, declaring and defining: Static Definitions.
-* C89: Standards.
-* C90: Standards.
-* C94: Standards.
-* C95: Standards.
-* C99: Standards.
-* C9X: Standards.
-* C_INCLUDE_PATH: Environment Variables.
-* calling functions through the function vector on the H8/300 processors: Function Attributes.
-* case labels in initializers: Designated Inits.
-* case ranges: Case Ranges.
-* case sensitivity and VMS: VMS Misc.
-* cast to a union: Cast to Union.
-* casts as lvalues: Lvalues.
-* cimag: Other Builtins.
-* cimagf: Other Builtins.
-* cimagl: Other Builtins.
-* code generation conventions: Code Gen Options.
-* code, mixed with declarations: Mixed Declarations.
-* command options: Invoking GCC.
-* comments, C++ style: C++ Comments.
-* comparison of signed and unsigned values, warning: Warning Options.
-* compiler bugs, reporting: Bug Reporting.
-* compiler compared to C++ preprocessor: G++ and GCC.
-* compiler options, C++: C++ Dialect Options.
-* compiler options, Objective-C: Objective-C Dialect Options.
-* compiler version, specifying: Target Options.
-* COMPILER_PATH: Environment Variables.
-* complex conjugation: Complex.
-* complex numbers: Complex.
-* compound expressions as lvalues: Lvalues.
-* compound literals: Compound Literals.
-* computed gotos: Labels as Values.
-* conditional expressions as lvalues: Lvalues.
-* conditional expressions, extensions: Conditionals.
-* conflicting types: Disappointments.
-* conj: Other Builtins.
-* conjf: Other Builtins.
-* conjl: Other Builtins.
-* const applied to function: Function Attributes.
-* const function attribute: Function Attributes.
-* constants in constraints: Simple Constraints.
-* constraint modifier characters: Modifiers.
-* constraint, matching: Simple Constraints.
-* constraints, asm: Constraints.
-* constraints, machine specific: Machine Constraints.
-* constructing calls: Constructing Calls.
-* constructor expressions: Compound Literals.
-* constructor function attribute: Function Attributes.
-* contributors: Contributors.
-* Convex options: Convex Options.
-* core dump: Bug Criteria.
-* cos: Other Builtins.
-* cosf: Other Builtins.
-* cosl: Other Builtins.
-* CPATH: Environment Variables.
-* CPLUS_INCLUDE_PATH: Environment Variables.
-* creal: Other Builtins.
-* crealf: Other Builtins.
-* creall: Other Builtins.
-* CRIS Options: CRIS Options.
-* cross compiling: Target Options.
-* D30V Options: D30V Options.
-* DBX: Interoperation.
-* deallocating variable length arrays: Variable Length.
-* debug_rtx: Bug Reporting.
-* debugging information options: Debugging Options.
-* debugging, 88k OCS: M88K Options.
-* declaration scope: Incompatibilities.
-* declarations inside expressions: Statement Exprs.
-* declarations, mixed with code: Mixed Declarations.
-* declaring attributes of functions: Function Attributes.
-* declaring static data in C++: Static Definitions.
-* defining static data in C++: Static Definitions.
-* dependencies for make as output: Environment Variables.
-* dependencies, make: Preprocessor Options.
-* DEPENDENCIES_OUTPUT: Environment Variables.
-* deprecated attribute.: Function Attributes.
-* designated initializers: Designated Inits.
-* designator lists: Designated Inits.
-* designators: Designated Inits.
-* destructor function attribute: Function Attributes.
-* diagnostic messages: Language Independent Options.
-* dialect options: C Dialect Options.
-* digits in constraint: Simple Constraints.
-* directory options: Directory Options.
-* divide instruction, 88k: M88K Options.
-* dollar signs in identifier names: Dollar Signs.
-* double-word arithmetic: Long Long.
-* downward funargs: Nested Functions.
-* DW bit (29k): AMD29K Options.
-* E in constraint: Simple Constraints.
-* earlyclobber operand: Modifiers.
-* eight bit data on the H8/300 and H8/300H: Function Attributes.
-* environment variables: Environment Variables.
-* error messages: Warnings and Errors.
-* escape sequences, traditional: C Dialect Options.
-* escaped newlines: Escaped Newlines.
-* exclamation point: Multi-Alternative.
-* exit: Other Builtins.
-* exit status and VMS: VMS Misc.
-* explicit register variables: Explicit Reg Vars.
-* expressions containing statements: Statement Exprs.
-* expressions, compound, as lvalues: Lvalues.
-* expressions, conditional, as lvalues: Lvalues.
-* expressions, constructor: Compound Literals.
-* extended asm: Extended Asm.
-* extensible constraints: Simple Constraints.
-* extensions, ?: <1>: Conditionals.
-* extensions, ?:: Lvalues.
-* extensions, C language: C Extensions.
-* extensions, C++ language: C++ Extensions.
-* external declaration scope: Incompatibilities.
-* F in constraint: Simple Constraints.
-* fabs: Other Builtins.
-* fabsf: Other Builtins.
-* fabsl: Other Builtins.
-* fatal signal: Bug Criteria.
-* FDL, GNU Free Documentation License: GNU Free Documentation License.
-* ffs: Other Builtins.
-* file name suffix: Overall Options.
-* file names: Link Options.
-* flexible array members: Zero Length.
-* float as function value type: Incompatibilities.
-* floating point precision <1>: Disappointments.
-* floating point precision: Optimize Options.
-* format function attribute: Function Attributes.
-* format_arg function attribute: Function Attributes.
-* Fortran: G++ and GCC.
-* forwarding calls: Constructing Calls.
-* fprintf: Other Builtins.
-* fprintf_unlocked: Other Builtins.
-* fputs: Other Builtins.
-* fputs_unlocked: Other Builtins.
-* freestanding environment: Standards.
-* freestanding implementation: Standards.
-* fscanf, and constant strings: Incompatibilities.
-* function addressability on the M32R/D: Function Attributes.
-* function attributes: Function Attributes.
-* function pointers, arithmetic: Pointer Arith.
-* function prototype declarations: Function Prototypes.
-* function without a prologue/epilogue code: Function Attributes.
-* function, size of pointer to: Pointer Arith.
-* functions called via pointer on the RS/6000 and PowerPC: Function Attributes.
-* functions in arbitrary sections: Function Attributes.
-* functions that are passed arguments in registers on the 386: Function Attributes.
-* functions that behave like malloc: Function Attributes.
-* functions that do not pop the argument stack on the 386: Function Attributes.
-* functions that do pop the argument stack on the 386: Function Attributes.
-* functions that have no side effects: Function Attributes.
-* functions that never return: Function Attributes.
-* functions that pop the argument stack on the 386: Function Attributes.
-* functions which are exported from a dll on PowerPC Windows NT: Function Attributes.
-* functions which are imported from a dll on PowerPC Windows NT: Function Attributes.
-* functions which specify exception handling on PowerPC Windows NT: Function Attributes.
-* functions with printf, scanf, strftime or strfmon style arguments: Function Attributes.
-* g in constraint: Simple Constraints.
-* G in constraint: Simple Constraints.
-* g++: Invoking G++.
-* G++: G++ and GCC.
-* GCC: G++ and GCC.
-* GCC command options: Invoking GCC.
-* gcc-bugs@gcc.gnu.org or bug-gcc@gnu.org: Bug Lists.
-* GCC_EXEC_PREFIX: Environment Variables.
-* gccbug script: gccbug.
-* generalized lvalues: Lvalues.
-* global offset table: Code Gen Options.
-* global register after longjmp: Global Reg Vars.
-* global register variables: Global Reg Vars.
-* GLOBALDEF: Global Declarations.
-* GLOBALREF: Global Declarations.
-* GLOBALVALUEDEF: Global Declarations.
-* GLOBALVALUEREF: Global Declarations.
-* GNAT: G++ and GCC.
-* goto with computed label: Labels as Values.
-* gp-relative references (MIPS): MIPS Options.
-* gprof: Debugging Options.
-* grouping options: Invoking GCC.
-* H in constraint: Simple Constraints.
-* hardware models and configurations, specifying: Submodel Options.
-* header files and VMS: Include Files and VMS.
-* hex floats: Hex Floats.
-* hosted environment <1>: C Dialect Options.
-* hosted environment: Standards.
-* hosted implementation: Standards.
-* HPPA Options: HPPA Options.
-* I in constraint: Simple Constraints.
-* i in constraint: Simple Constraints.
-* i386 Options: i386 and x86-64 Options.
-* IA-64 Options: IA-64 Options.
-* IBM RS/6000 and PowerPC Options: RS/6000 and PowerPC Options.
-* IBM RT options: RT Options.
-* IBM RT PC: Interoperation.
-* identifier names, dollar signs in: Dollar Signs.
-* identifiers, names in assembler code: Asm Labels.
-* identifying source, compiler (88k): M88K Options.
-* imaxabs: Other Builtins.
-* implementation-defined behavior, C language: C Implementation.
-* implied #pragma implementation: C++ Interface.
-* include files and VMS: Include Files and VMS.
-* incompatibilities of GCC: Incompatibilities.
-* increment operators: Bug Criteria.
-* index: Other Builtins.
-* indirect calls on ARM: Function Attributes.
-* init_priority attribute: C++ Attributes.
-* initializations in expressions: Compound Literals.
-* initializers with labeled elements: Designated Inits.
-* initializers, non-constant: Initializers.
-* inline automatic for C++ member fns: Inline.
-* inline functions: Inline.
-* inline functions, omission of: Inline.
-* inlining and C++ pragmas: C++ Interface.
-* installation trouble: Trouble.
-* integrating function code: Inline.
-* Intel 386 Options: i386 and x86-64 Options.
-* interface and implementation headers, C++: C++ Interface.
-* intermediate C version, nonexistent: G++ and GCC.
-* interrupt handler functions: Function Attributes.
-* interrupt handler functions on the H8/300 and SH processors: Function Attributes.
-* introduction: Top.
-* invalid assembly code: Bug Criteria.
-* invalid input: Bug Criteria.
-* invoking g++: Invoking G++.
-* ISO 9899: Standards.
-* ISO C: Standards.
-* ISO C standard: Standards.
-* ISO C89: Standards.
-* ISO C90: Standards.
-* ISO C94: Standards.
-* ISO C95: Standards.
-* ISO C99: Standards.
-* ISO C9X: Standards.
-* ISO support: C Dialect Options.
-* ISO/IEC 9899: Standards.
-* Java: G++ and GCC.
-* java_interface attribute: C++ Attributes.
-* kernel and user registers (29k): AMD29K Options.
-* keywords, alternate: Alternate Keywords.
-* known causes of trouble: Trouble.
-* labeled elements in initializers: Designated Inits.
-* labels as values: Labels as Values.
-* labs: Other Builtins.
-* LANG: Environment Variables.
-* language dialect options: C Dialect Options.
-* large bit shifts (88k): M88K Options.
-* LC_ALL: Environment Variables.
-* LC_CTYPE: Environment Variables.
-* LC_MESSAGES: Environment Variables.
-* length-zero arrays: Zero Length.
-* Libraries: Link Options.
-* LIBRARY_PATH: Environment Variables.
-* link options: Link Options.
-* LL integer suffix: Long Long.
-* llabs: Other Builtins.
-* load address instruction: Simple Constraints.
-* local labels: Local Labels.
-* local variables in macros: Typeof.
-* local variables, specifying registers: Local Reg Vars.
-* locale: Environment Variables.
-* locale definition: Environment Variables.
-* long long data types: Long Long.
-* longjmp: Global Reg Vars.
-* longjmp and automatic variables: C Dialect Options.
-* longjmp incompatibilities: Incompatibilities.
-* longjmp warnings: Warning Options.
-* lvalues, generalized: Lvalues.
-* m in constraint: Simple Constraints.
-* M32R/D options: M32R/D Options.
-* M680x0 options: M680x0 Options.
-* M68hc1x options: M68hc1x Options.
-* M88k options: M88K Options.
-* machine dependent options: Submodel Options.
-* machine specific constraints: Machine Constraints.
-* macro with variable arguments: Variadic Macros.
-* macros containing asm: Extended Asm.
-* macros, inline alternative: Inline.
-* macros, local labels: Local Labels.
-* macros, local variables in: Typeof.
-* macros, statements in expressions: Statement Exprs.
-* macros, types of arguments: Typeof.
-* main and the exit status: VMS Misc.
-* make: Preprocessor Options.
-* malloc attribute: Function Attributes.
-* matching constraint: Simple Constraints.
-* maximum operator: Min and Max.
-* MCore options: MCore Options.
-* member fns, automatically inline: Inline.
-* memcmp: Other Builtins.
-* memcpy: Other Builtins.
-* memory model (29k): AMD29K Options.
-* memory references in constraints: Simple Constraints.
-* memset: Other Builtins.
-* message formatting: Language Independent Options.
-* messages, warning: Warning Options.
-* messages, warning and error: Warnings and Errors.
-* middle-operands, omitted: Conditionals.
-* minimum operator: Min and Max.
-* MIPS options: MIPS Options.
-* misunderstandings in C++: C++ Misunderstandings.
-* mixed declarations and code: Mixed Declarations.
-* mktemp, and constant strings: Incompatibilities.
-* MMIX Options: MMIX Options.
-* MN10200 options: MN10200 Options.
-* MN10300 options: MN10300 Options.
-* mode attribute: Variable Attributes.
-* modifiers in constraints: Modifiers.
-* multi-line string literals: Multi-line Strings.
-* multiple alternative constraints: Multi-Alternative.
-* multiprecision arithmetic: Long Long.
-* n in constraint: Simple Constraints.
-* name augmentation: VMS Misc.
-* names used in assembler code: Asm Labels.
-* naming convention, implementation headers: C++ Interface.
-* nested functions: Nested Functions.
-* newlines (escaped): Escaped Newlines.
-* no_instrument_function function attribute: Function Attributes.
-* nocommon attribute: Variable Attributes.
-* noinline function attribute: Function Attributes.
-* non-constant initializers: Initializers.
-* non-static inline function: Inline.
-* noreturn function attribute: Function Attributes.
-* NS32K options: NS32K Options.
-* o in constraint: Simple Constraints.
-* OBJC_INCLUDE_PATH: Environment Variables.
-* Objective-C: G++ and GCC.
-* Objective-C options, command line: Objective-C Dialect Options.
-* OCS (88k): M88K Options.
-* offsettable address: Simple Constraints.
-* old-style function definitions: Function Prototypes.
-* omitted middle-operands: Conditionals.
-* open coding: Inline.
-* operand constraints, asm: Constraints.
-* optimize options: Optimize Options.
-* options to control diagnostics formatting: Language Independent Options.
-* options to control warnings: Warning Options.
-* options, C++: C++ Dialect Options.
-* options, code generation: Code Gen Options.
-* options, debugging: Debugging Options.
-* options, dialect: C Dialect Options.
-* options, directory search: Directory Options.
-* options, GCC command: Invoking GCC.
-* options, grouping: Invoking GCC.
-* options, linking: Link Options.
-* options, Objective-C: Objective-C Dialect Options.
-* options, optimization: Optimize Options.
-* options, order: Invoking GCC.
-* options, preprocessor: Preprocessor Options.
-* order of evaluation, side effects: Non-bugs.
-* order of options: Invoking GCC.
-* other register constraints: Simple Constraints.
-* output file option: Overall Options.
-* overloaded virtual fn, warning: C++ Dialect Options.
-* p in constraint: Simple Constraints.
-* packed attribute: Variable Attributes.
-* parameter forward declaration: Variable Length.
-* parameters, aliased: Code Gen Options.
-* PDP-11 Options: PDP-11 Options.
-* PIC: Code Gen Options.
-* pmf: Bound member functions.
-* pointer arguments: Function Attributes.
-* pointer to member function: Bound member functions.
-* portions of temporary objects, pointers to: Temporaries.
-* pragma, extern_prefix: Tru64 Pragmas.
-* pragma, long_calls: ARM Pragmas.
-* pragma, long_calls_off: ARM Pragmas.
-* pragma, mark: Darwin Pragmas.
-* pragma, no_long_calls: ARM Pragmas.
-* pragma, options align: Darwin Pragmas.
-* pragma, reason for not using: Function Attributes.
-* pragma, redefine_extname: Solaris Pragmas.
-* pragma, segment: Darwin Pragmas.
-* pragma, unused: Darwin Pragmas.
-* pragmas: Pragmas.
-* pragmas in C++, effect on inlining: C++ Interface.
-* pragmas, interface and implementation: C++ Interface.
-* pragmas, warning of unknown: Warning Options.
-* preprocessing numbers: Incompatibilities.
-* preprocessing tokens: Incompatibilities.
-* preprocessor options: Preprocessor Options.
-* printf: Other Builtins.
-* printf_unlocked: Other Builtins.
-* processor selection (29k): AMD29K Options.
-* prof: Debugging Options.
-* promotion of formal parameters: Function Prototypes.
-* pure function attribute: Function Attributes.
-* push address instruction: Simple Constraints.
-* qsort, and global register variables: Global Reg Vars.
-* question mark: Multi-Alternative.
-* r in constraint: Simple Constraints.
-* r0-relative references (88k): M88K Options.
-* ranges in case statements: Case Ranges.
-* read-only strings: Incompatibilities.
-* register positions in frame (88k): M88K Options.
-* register variable after longjmp: Global Reg Vars.
-* registers: Extended Asm.
-* registers for local variables: Local Reg Vars.
-* registers in constraints: Simple Constraints.
-* registers, global allocation: Explicit Reg Vars.
-* registers, global variables in: Global Reg Vars.
-* reordering, warning <1>: Warning Options.
-* reordering, warning: C++ Dialect Options.
-* reporting bugs: Bugs.
-* rest argument (in macro): Variadic Macros.
-* restricted pointers: Restricted Pointers.
-* restricted references: Restricted Pointers.
-* restricted this pointer: Restricted Pointers.
-* return value of main: VMS Misc.
-* rindex: Other Builtins.
-* RS/6000 and PowerPC Options: RS/6000 and PowerPC Options.
-* RT options: RT Options.
-* RT PC: Interoperation.
-* RTTI: Vague Linkage.
-* run-time options: Code Gen Options.
-* s in constraint: Simple Constraints.
-* S/390 and zSeries Options: S/390 and zSeries Options.
-* scanf, and constant strings: Incompatibilities.
-* scope of a variable length array: Variable Length.
-* scope of declaration: Disappointments.
-* scope of external declarations: Incompatibilities.
-* search path: Directory Options.
-* section function attribute: Function Attributes.
-* section variable attribute: Variable Attributes.
-* sequential consistency on 88k: M88K Options.
-* setjmp: Global Reg Vars.
-* setjmp incompatibilities: Incompatibilities.
-* shared strings: Incompatibilities.
-* shared variable attribute: Variable Attributes.
-* shared VMS run time system: VMS Misc.
-* side effect in ?:: Conditionals.
-* side effects, macro argument: Statement Exprs.
-* side effects, order of evaluation: Non-bugs.
-* signal handler functions on the AVR processors: Function Attributes.
-* signed and unsigned values, comparison warning: Warning Options.
-* simple constraints: Simple Constraints.
-* sin: Other Builtins.
-* sinf: Other Builtins.
-* sinl: Other Builtins.
-* sizeof: Typeof.
-* smaller data references: M32R/D Options.
-* smaller data references (88k): M88K Options.
-* smaller data references (MIPS): MIPS Options.
-* smaller data references (PowerPC): RS/6000 and PowerPC Options.
-* SPARC options: SPARC Options.
-* Spec Files: Spec Files.
-* specified registers: Explicit Reg Vars.
-* specifying compiler version and target machine: Target Options.
-* specifying hardware config: Submodel Options.
-* specifying machine version: Target Options.
-* specifying registers for local variables: Local Reg Vars.
-* sqrt: Other Builtins.
-* sqrtf: Other Builtins.
-* sqrtl: Other Builtins.
-* sscanf, and constant strings: Incompatibilities.
-* stack checks (29k): AMD29K Options.
-* statements inside expressions: Statement Exprs.
-* static data in C++, declaring and defining: Static Definitions.
-* stdarg.h and RT PC: RT Options.
-* storem bug (29k): AMD29K Options.
-* strcat: Other Builtins.
-* strchr: Other Builtins.
-* strcmp: Other Builtins.
-* strcpy: Other Builtins.
-* strcspn: Other Builtins.
-* string constants: Incompatibilities.
-* strlen: Other Builtins.
-* strncat: Other Builtins.
-* strncmp: Other Builtins.
-* strncpy: Other Builtins.
-* strpbrk: Other Builtins.
-* strrchr: Other Builtins.
-* strspn: Other Builtins.
-* strstr: Other Builtins.
-* struct: Unnamed Fields.
-* structure passing (88k): M88K Options.
-* structures: Incompatibilities.
-* structures, constructor expression: Compound Literals.
-* submodel options: Submodel Options.
-* subscripting: Subscripting.
-* subscripting and function values: Subscripting.
-* suffixes for C++ source: Invoking G++.
-* SUNPRO_DEPENDENCIES: Environment Variables.
-* suppressing warnings: Warning Options.
-* surprises in C++: C++ Misunderstandings.
-* SVr4: M88K Options.
-* syntax checking: Warning Options.
-* synthesized methods, warning: C++ Dialect Options.
-* system headers, warnings from: Warning Options.
-* target machine, specifying: Target Options.
-* target options: Target Options.
-* TC1: Standards.
-* TC2: Standards.
-* Technical Corrigenda: Standards.
-* Technical Corrigendum 1: Standards.
-* Technical Corrigendum 2: Standards.
-* template instantiation: Template Instantiation.
-* temporaries, lifetime of: Temporaries.
-* thunks: Nested Functions.
-* tiny data section on the H8/300H: Function Attributes.
-* TMPDIR: Environment Variables.
-* TMS320C3x/C4x Options: TMS320C3x/C4x Options.
-* traditional C language: C Dialect Options.
-* type alignment: Alignment.
-* type attributes: Type Attributes.
-* type_info: Vague Linkage.
-* typedef names as function parameters: Incompatibilities.
-* typeof: Typeof.
-* ULL integer suffix: Long Long.
-* Ultrix calling convention: Interoperation.
-* undefined behavior: Bug Criteria.
-* undefined function value: Bug Criteria.
-* underscores in variables in macros: Typeof.
-* underscores, avoiding (88k): M88K Options.
-* union: Unnamed Fields.
-* union, casting to a: Cast to Union.
-* unions: Incompatibilities.
-* unknown pragmas, warning: Warning Options.
-* unresolved references and -nodefaultlibs: Link Options.
-* unresolved references and -nostdlib: Link Options.
-* unused attribute.: Function Attributes.
-* used attribute.: Function Attributes.
-* V in constraint: Simple Constraints.
-* V850 Options: V850 Options.
-* vague linkage: Vague Linkage.
-* value after longjmp: Global Reg Vars.
-* varargs.h and RT PC: RT Options.
-* variable addressability on the M32R/D: Variable Attributes.
-* variable alignment: Alignment.
-* variable attributes: Variable Attributes.
-* variable number of arguments: Variadic Macros.
-* variable-length array scope: Variable Length.
-* variable-length arrays: Variable Length.
-* variables in specified registers: Explicit Reg Vars.
-* variables, local, in macros: Typeof.
-* variadic macros: Variadic Macros.
-* VAX calling convention: Interoperation.
-* VAX options: VAX Options.
-* VAXCRTL: VMS Misc.
-* VLAs: Variable Length.
-* VMS and case sensitivity: VMS Misc.
-* VMS and include files: Include Files and VMS.
-* void pointers, arithmetic: Pointer Arith.
-* void, size of pointer to: Pointer Arith.
-* volatile access: Volatiles.
-* volatile applied to function: Function Attributes.
-* volatile read: Volatiles.
-* volatile write: Volatiles.
-* vtable: Vague Linkage.
-* warning for comparison of signed and unsigned values: Warning Options.
-* warning for overloaded virtual fn: C++ Dialect Options.
-* warning for reordering of member initializers <1>: Warning Options.
-* warning for reordering of member initializers: C++ Dialect Options.
-* warning for synthesized methods: C++ Dialect Options.
-* warning for unknown pragmas: Warning Options.
-* warning messages: Warning Options.
-* warnings from system headers: Warning Options.
-* warnings vs errors: Warnings and Errors.
-* weak attribute: Function Attributes.
-* whitespace: Incompatibilities.
-* X in constraint: Simple Constraints.
-* X3.159-1989: Standards.
-* x86-64 Options: i386 and x86-64 Options.
-* Xstormy16 Options: Xstormy16 Options.
-* Xtensa Options: Xtensa Options.
-* zero division on 88k: M88K Options.
-* zero-length arrays: Zero Length.
-
-
-This is doc/gcc.info, produced by makeinfo version 4.5 from
+This is doc/gcc.info, produced by makeinfo version 4.11 from
doc/gcc.texi.
INFO-DIR-SECTION Programming
funds for GNU development.
\1f
-File: gcc.info, Node: Warning Options, Next: Debugging Options, Prev: Language Independent Options, Up: Invoking GCC
+File: gcc.info, Node: Other Builtins, Next: Target Builtins, Prev: Vector Extensions, Up: C Extensions
+
+5.44 Other built-in functions provided by GCC
+=============================================
+
+GCC provides a large number of built-in functions other than the ones
+mentioned above. Some of these are for internal use in the processing
+of exceptions or variable-length argument lists and will not be
+documented here because they may change from time to time; we do not
+recommend general use of these functions.
+
+ The remaining functions are provided for optimization purposes.
+
+ GCC includes built-in versions of many of the functions in the
+standard C library. The versions prefixed with `__builtin_' will
+always be treated as having the same meaning as the C library function
+even if you specify the `-fno-builtin' option. (*note C Dialect
+Options::) Many of these functions are only optimized in certain cases;
+if they are not optimized in a particular case, a call to the library
+function will be emitted.
+
+ The functions `abort', `exit', `_Exit' and `_exit' are recognized
+and presumed not to return, but otherwise are not built in. `_exit' is
+not recognized in strict ISO C mode (`-ansi', `-std=c89' or
+`-std=c99'). `_Exit' is not recognized in strict C89 mode (`-ansi' or
+`-std=c89').
+
+ Outside strict ISO C mode, the functions `alloca', `bcmp', `bzero',
+`index', `rindex', `ffs', `fputs_unlocked', `printf_unlocked' and
+`fprintf_unlocked' may be handled as built-in functions. All these
+functions have corresponding versions prefixed with `__builtin_', which
+may be used even in strict C89 mode.
+
+ The ISO C99 functions `conj', `conjf', `conjl', `creal', `crealf',
+`creall', `cimag', `cimagf', `cimagl', `llabs' and `imaxabs' are
+handled as built-in functions except in strict ISO C89 mode. There are
+also built-in versions of the ISO C99 functions `cosf', `cosl',
+`fabsf', `fabsl', `sinf', `sinl', `sqrtf', and `sqrtl', that are
+recognized in any mode since ISO C89 reserves these names for the
+purpose to which ISO C99 puts them. All these functions have
+corresponding versions prefixed with `__builtin_'.
+
+ The ISO C89 functions `abs', `cos', `fabs', `fprintf', `fputs',
+`labs', `memcmp', `memcpy', `memset', `printf', `sin', `sqrt', `strcat',
+`strchr', `strcmp', `strcpy', `strcspn', `strlen', `strncat',
+`strncmp', `strncpy', `strpbrk', `strrchr', `strspn', and `strstr' are
+all recognized as built-in functions unless `-fno-builtin' is specified
+(or `-fno-builtin-FUNCTION' is specified for an individual function).
+All of these functions have corresponding versions prefixed with
+`__builtin_'.
+
+ GCC provides built-in versions of the ISO C99 floating point
+comparison macros that avoid raising exceptions for unordered operands.
+They have the same names as the standard macros ( `isgreater',
+`isgreaterequal', `isless', `islessequal', `islessgreater', and
+`isunordered') , with `__builtin_' prefixed. We intend for a library
+implementor to be able to simply `#define' each standard macro to its
+built-in equivalent.
+
+ -- Built-in Function: int __builtin_types_compatible_p (TYPE1, TYPE2)
+ You can use the built-in function `__builtin_types_compatible_p' to
+ determine whether two types are the same.
+
+ This built-in function returns 1 if the unqualified versions of the
+ types TYPE1 and TYPE2 (which are types, not expressions) are
+ compatible, 0 otherwise. The result of this built-in function can
+ be used in integer constant expressions.
+
+ This built-in function ignores top level qualifiers (e.g., `const',
+ `volatile'). For example, `int' is equivalent to `const int'.
+
+ The type `int[]' and `int[5]' are compatible. On the other hand,
+ `int' and `char *' are not compatible, even if the size of their
+ types, on the particular architecture are the same. Also, the
+ amount of pointer indirection is taken into account when
+ determining similarity. Consequently, `short *' is not similar to
+ `short **'. Furthermore, two types that are typedefed are
+ considered compatible if their underlying types are compatible.
+
+ An `enum' type is considered to be compatible with another `enum'
+ type. For example, `enum {foo, bar}' is similar to `enum {hot,
+ dog}'.
+
+ You would typically use this function in code whose execution
+ varies depending on the arguments' types. For example:
+
+ #define foo(x) \
+ ({ \
+ typeof (x) tmp; \
+ if (__builtin_types_compatible_p (typeof (x), long double)) \
+ tmp = foo_long_double (tmp); \
+ else if (__builtin_types_compatible_p (typeof (x), double)) \
+ tmp = foo_double (tmp); \
+ else if (__builtin_types_compatible_p (typeof (x), float)) \
+ tmp = foo_float (tmp); \
+ else \
+ abort (); \
+ tmp; \
+ })
+
+ _Note:_ This construct is only available for C.
+
+
+ -- Built-in Function: TYPE __builtin_choose_expr (CONST_EXP, EXP1,
+ EXP2)
+ You can use the built-in function `__builtin_choose_expr' to
+ evaluate code depending on the value of a constant expression.
+ This built-in function returns EXP1 if CONST_EXP, which is a
+ constant expression that must be able to be determined at compile
+ time, is nonzero. Otherwise it returns 0.
+
+ This built-in function is analogous to the `? :' operator in C,
+ except that the expression returned has its type unaltered by
+ promotion rules. Also, the built-in function does not evaluate
+ the expression that was not chosen. For example, if CONST_EXP
+ evaluates to true, EXP2 is not evaluated even if it has
+ side-effects.
+
+ This built-in function can return an lvalue if the chosen argument
+ is an lvalue.
+
+ If EXP1 is returned, the return type is the same as EXP1's type.
+ Similarly, if EXP2 is returned, its return type is the same as
+ EXP2.
+
+ Example:
+
+ #define foo(x) \
+ __builtin_choose_expr (__builtin_types_compatible_p (typeof (x), double), \
+ foo_double (x), \
+ __builtin_choose_expr (__builtin_types_compatible_p (typeof (x), float), \
+ foo_float (x), \
+ /* The void expression results in a compile-time error \
+ when assigning the result to something. */ \
+ (void)0))
+
+ _Note:_ This construct is only available for C. Furthermore, the
+ unused expression (EXP1 or EXP2 depending on the value of
+ CONST_EXP) may still generate syntax errors. This may change in
+ future revisions.
+
+
+ -- Built-in Function: int __builtin_constant_p (EXP)
+ You can use the built-in function `__builtin_constant_p' to
+ determine if a value is known to be constant at compile-time and
+ hence that GCC can perform constant-folding on expressions
+ involving that value. The argument of the function is the value
+ to test. The function returns the integer 1 if the argument is
+ known to be a compile-time constant and 0 if it is not known to be
+ a compile-time constant. A return of 0 does not indicate that the
+ value is _not_ a constant, but merely that GCC cannot prove it is
+ a constant with the specified value of the `-O' option.
+
+ You would typically use this function in an embedded application
+ where memory was a critical resource. If you have some complex
+ calculation, you may want it to be folded if it involves
+ constants, but need to call a function if it does not. For
+ example:
+
+ #define Scale_Value(X) \
+ (__builtin_constant_p (X) \
+ ? ((X) * SCALE + OFFSET) : Scale (X))
+
+ You may use this built-in function in either a macro or an inline
+ function. However, if you use it in an inlined function and pass
+ an argument of the function as the argument to the built-in, GCC
+ will never return 1 when you call the inline function with a
+ string constant or compound literal (*note Compound Literals::)
+ and will not return 1 when you pass a constant numeric value to
+ the inline function unless you specify the `-O' option.
+
+ You may also use `__builtin_constant_p' in initializers for static
+ data. For instance, you can write
+
+ static const int table[] = {
+ __builtin_constant_p (EXPRESSION) ? (EXPRESSION) : -1,
+ /* ... */
+ };
+
+ This is an acceptable initializer even if EXPRESSION is not a
+ constant expression. GCC must be more conservative about
+ evaluating the built-in in this case, because it has no
+ opportunity to perform optimization.
+
+ Previous versions of GCC did not accept this built-in in data
+ initializers. The earliest version where it is completely safe is
+ 3.0.1.
+
+ -- Built-in Function: long __builtin_expect (long EXP, long C)
+ You may use `__builtin_expect' to provide the compiler with branch
+ prediction information. In general, you should prefer to use
+ actual profile feedback for this (`-fprofile-arcs'), as
+ programmers are notoriously bad at predicting how their programs
+ actually perform. However, there are applications in which this
+ data is hard to collect.
+
+ The return value is the value of EXP, which should be an integral
+ expression. The value of C must be a compile-time constant. The
+ semantics of the built-in are that it is expected that EXP == C.
+ For example:
+
+ if (__builtin_expect (x, 0))
+ foo ();
+
+ would indicate that we do not expect to call `foo', since we
+ expect `x' to be zero. Since you are limited to integral
+ expressions for EXP, you should use constructions such as
+
+ if (__builtin_expect (ptr != NULL, 1))
+ error ();
+
+ when testing pointer or floating-point values.
+
+ -- Built-in Function: void __builtin_prefetch (const void *ADDR, ...)
+ This function is used to minimize cache-miss latency by moving
+ data into a cache before it is accessed. You can insert calls to
+ `__builtin_prefetch' into code for which you know addresses of
+ data in memory that is likely to be accessed soon. If the target
+ supports them, data prefetch instructions will be generated. If
+ the prefetch is done early enough before the access then the data
+ will be in the cache by the time it is accessed.
+
+ The value of ADDR is the address of the memory to prefetch. There
+ are two optional arguments, RW and LOCALITY. The value of RW is a
+ compile-time constant one or zero; one means that the prefetch is
+ preparing for a write to the memory address and zero, the default,
+ means that the prefetch is preparing for a read. The value
+ LOCALITY must be a compile-time constant integer between zero and
+ three. A value of zero means that the data has no temporal
+ locality, so it need not be left in the cache after the access. A
+ value of three means that the data has a high degree of temporal
+ locality and should be left in all levels of cache possible.
+ Values of one and two mean, respectively, a low or moderate degree
+ of temporal locality. The default is three.
+
+ for (i = 0; i < n; i++)
+ {
+ a[i] = a[i] + b[i];
+ __builtin_prefetch (&a[i+j], 1, 1);
+ __builtin_prefetch (&b[i+j], 0, 1);
+ /* ... */
+ }
+
+ Data prefetch does not generate faults if ADDR is invalid, but the
+ address expression itself must be valid. For example, a prefetch
+ of `p->next' will not fault if `p->next' is not a valid address,
+ but evaluation will fault if `p' is not a valid address.
+
+ If the target does not support data prefetch, the address
+ expression is evaluated if it includes side effects but no other
+ code is generated and GCC does not issue a warning.
+
+\1f
+File: gcc.info, Node: Target Builtins, Next: Pragmas, Prev: Other Builtins, Up: C Extensions
+
+5.45 Built-in Functions Specific to Particular Target Machines
+==============================================================
+
+On some target machines, GCC supports many built-in functions specific
+to those machines. Generally these generate calls to specific machine
+instructions, but allow the compiler to schedule those calls.
+
+* Menu:
+
+* X86 Built-in Functions::
+* PowerPC AltiVec Built-in Functions::
+
+\1f
+File: gcc.info, Node: X86 Built-in Functions, Next: PowerPC AltiVec Built-in Functions, Up: Target Builtins
+
+5.45.1 X86 Built-in Functions
+-----------------------------
+
+These built-in functions are available for the i386 and x86-64 family
+of computers, depending on the command-line switches used.
+
+ The following machine modes are available for use with MMX built-in
+functions (*note Vector Extensions::): `V2SI' for a vector of two
+32-bit integers, `V4HI' for a vector of four 16-bit integers, and
+`V8QI' for a vector of eight 8-bit integers. Some of the built-in
+functions operate on MMX registers as a whole 64-bit entity, these use
+`DI' as their mode.
+
+ If 3Dnow extensions are enabled, `V2SF' is used as a mode for a
+vector of two 32-bit floating point values.
+
+ If SSE extensions are enabled, `V4SF' is used for a vector of four
+32-bit floating point values. Some instructions use a vector of four
+32-bit integers, these use `V4SI'. Finally, some instructions operate
+on an entire vector register, interpreting it as a 128-bit integer,
+these use mode `TI'.
+
+ The following built-in functions are made available by `-mmmx'. All
+of them generate the machine instruction that is part of the name.
+
+ v8qi __builtin_ia32_paddb (v8qi, v8qi)
+ v4hi __builtin_ia32_paddw (v4hi, v4hi)
+ v2si __builtin_ia32_paddd (v2si, v2si)
+ v8qi __builtin_ia32_psubb (v8qi, v8qi)
+ v4hi __builtin_ia32_psubw (v4hi, v4hi)
+ v2si __builtin_ia32_psubd (v2si, v2si)
+ v8qi __builtin_ia32_paddsb (v8qi, v8qi)
+ v4hi __builtin_ia32_paddsw (v4hi, v4hi)
+ v8qi __builtin_ia32_psubsb (v8qi, v8qi)
+ v4hi __builtin_ia32_psubsw (v4hi, v4hi)
+ v8qi __builtin_ia32_paddusb (v8qi, v8qi)
+ v4hi __builtin_ia32_paddusw (v4hi, v4hi)
+ v8qi __builtin_ia32_psubusb (v8qi, v8qi)
+ v4hi __builtin_ia32_psubusw (v4hi, v4hi)
+ v4hi __builtin_ia32_pmullw (v4hi, v4hi)
+ v4hi __builtin_ia32_pmulhw (v4hi, v4hi)
+ di __builtin_ia32_pand (di, di)
+ di __builtin_ia32_pandn (di,di)
+ di __builtin_ia32_por (di, di)
+ di __builtin_ia32_pxor (di, di)
+ v8qi __builtin_ia32_pcmpeqb (v8qi, v8qi)
+ v4hi __builtin_ia32_pcmpeqw (v4hi, v4hi)
+ v2si __builtin_ia32_pcmpeqd (v2si, v2si)
+ v8qi __builtin_ia32_pcmpgtb (v8qi, v8qi)
+ v4hi __builtin_ia32_pcmpgtw (v4hi, v4hi)
+ v2si __builtin_ia32_pcmpgtd (v2si, v2si)
+ v8qi __builtin_ia32_punpckhbw (v8qi, v8qi)
+ v4hi __builtin_ia32_punpckhwd (v4hi, v4hi)
+ v2si __builtin_ia32_punpckhdq (v2si, v2si)
+ v8qi __builtin_ia32_punpcklbw (v8qi, v8qi)
+ v4hi __builtin_ia32_punpcklwd (v4hi, v4hi)
+ v2si __builtin_ia32_punpckldq (v2si, v2si)
+ v8qi __builtin_ia32_packsswb (v4hi, v4hi)
+ v4hi __builtin_ia32_packssdw (v2si, v2si)
+ v8qi __builtin_ia32_packuswb (v4hi, v4hi)
+
+ The following built-in functions are made available either with
+`-msse', or with a combination of `-m3dnow' and `-march=athlon'. All
+of them generate the machine instruction that is part of the name.
+
+ v4hi __builtin_ia32_pmulhuw (v4hi, v4hi)
+ v8qi __builtin_ia32_pavgb (v8qi, v8qi)
+ v4hi __builtin_ia32_pavgw (v4hi, v4hi)
+ v4hi __builtin_ia32_psadbw (v8qi, v8qi)
+ v8qi __builtin_ia32_pmaxub (v8qi, v8qi)
+ v4hi __builtin_ia32_pmaxsw (v4hi, v4hi)
+ v8qi __builtin_ia32_pminub (v8qi, v8qi)
+ v4hi __builtin_ia32_pminsw (v4hi, v4hi)
+ int __builtin_ia32_pextrw (v4hi, int)
+ v4hi __builtin_ia32_pinsrw (v4hi, int, int)
+ int __builtin_ia32_pmovmskb (v8qi)
+ void __builtin_ia32_maskmovq (v8qi, v8qi, char *)
+ void __builtin_ia32_movntq (di *, di)
+ void __builtin_ia32_sfence (void)
+
+ The following built-in functions are available when `-msse' is used.
+All of them generate the machine instruction that is part of the name.
+
+ int __builtin_ia32_comieq (v4sf, v4sf)
+ int __builtin_ia32_comineq (v4sf, v4sf)
+ int __builtin_ia32_comilt (v4sf, v4sf)
+ int __builtin_ia32_comile (v4sf, v4sf)
+ int __builtin_ia32_comigt (v4sf, v4sf)
+ int __builtin_ia32_comige (v4sf, v4sf)
+ int __builtin_ia32_ucomieq (v4sf, v4sf)
+ int __builtin_ia32_ucomineq (v4sf, v4sf)
+ int __builtin_ia32_ucomilt (v4sf, v4sf)
+ int __builtin_ia32_ucomile (v4sf, v4sf)
+ int __builtin_ia32_ucomigt (v4sf, v4sf)
+ int __builtin_ia32_ucomige (v4sf, v4sf)
+ v4sf __builtin_ia32_addps (v4sf, v4sf)
+ v4sf __builtin_ia32_subps (v4sf, v4sf)
+ v4sf __builtin_ia32_mulps (v4sf, v4sf)
+ v4sf __builtin_ia32_divps (v4sf, v4sf)
+ v4sf __builtin_ia32_addss (v4sf, v4sf)
+ v4sf __builtin_ia32_subss (v4sf, v4sf)
+ v4sf __builtin_ia32_mulss (v4sf, v4sf)
+ v4sf __builtin_ia32_divss (v4sf, v4sf)
+ v4si __builtin_ia32_cmpeqps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpltps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpleps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpgtps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpgeps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpunordps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpneqps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpnltps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpnleps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpngtps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpngeps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpordps (v4sf, v4sf)
+ v4si __builtin_ia32_cmpeqss (v4sf, v4sf)
+ v4si __builtin_ia32_cmpltss (v4sf, v4sf)
+ v4si __builtin_ia32_cmpless (v4sf, v4sf)
+ v4si __builtin_ia32_cmpgtss (v4sf, v4sf)
+ v4si __builtin_ia32_cmpgess (v4sf, v4sf)
+ v4si __builtin_ia32_cmpunordss (v4sf, v4sf)
+ v4si __builtin_ia32_cmpneqss (v4sf, v4sf)
+ v4si __builtin_ia32_cmpnlts (v4sf, v4sf)
+ v4si __builtin_ia32_cmpnless (v4sf, v4sf)
+ v4si __builtin_ia32_cmpngtss (v4sf, v4sf)
+ v4si __builtin_ia32_cmpngess (v4sf, v4sf)
+ v4si __builtin_ia32_cmpordss (v4sf, v4sf)
+ v4sf __builtin_ia32_maxps (v4sf, v4sf)
+ v4sf __builtin_ia32_maxss (v4sf, v4sf)
+ v4sf __builtin_ia32_minps (v4sf, v4sf)
+ v4sf __builtin_ia32_minss (v4sf, v4sf)
+ v4sf __builtin_ia32_andps (v4sf, v4sf)
+ v4sf __builtin_ia32_andnps (v4sf, v4sf)
+ v4sf __builtin_ia32_orps (v4sf, v4sf)
+ v4sf __builtin_ia32_xorps (v4sf, v4sf)
+ v4sf __builtin_ia32_movss (v4sf, v4sf)
+ v4sf __builtin_ia32_movhlps (v4sf, v4sf)
+ v4sf __builtin_ia32_movlhps (v4sf, v4sf)
+ v4sf __builtin_ia32_unpckhps (v4sf, v4sf)
+ v4sf __builtin_ia32_unpcklps (v4sf, v4sf)
+ v4sf __builtin_ia32_cvtpi2ps (v4sf, v2si)
+ v4sf __builtin_ia32_cvtsi2ss (v4sf, int)
+ v2si __builtin_ia32_cvtps2pi (v4sf)
+ int __builtin_ia32_cvtss2si (v4sf)
+ v2si __builtin_ia32_cvttps2pi (v4sf)
+ int __builtin_ia32_cvttss2si (v4sf)
+ v4sf __builtin_ia32_rcpps (v4sf)
+ v4sf __builtin_ia32_rsqrtps (v4sf)
+ v4sf __builtin_ia32_sqrtps (v4sf)
+ v4sf __builtin_ia32_rcpss (v4sf)
+ v4sf __builtin_ia32_rsqrtss (v4sf)
+ v4sf __builtin_ia32_sqrtss (v4sf)
+ v4sf __builtin_ia32_shufps (v4sf, v4sf, int)
+ void __builtin_ia32_movntps (float *, v4sf)
+ int __builtin_ia32_movmskps (v4sf)
+
+ The following built-in functions are available when `-msse' is used.
+
+`v4sf __builtin_ia32_loadaps (float *)'
+ Generates the `movaps' machine instruction as a load from memory.
+
+`void __builtin_ia32_storeaps (float *, v4sf)'
+ Generates the `movaps' machine instruction as a store to memory.
+
+`v4sf __builtin_ia32_loadups (float *)'
+ Generates the `movups' machine instruction as a load from memory.
+
+`void __builtin_ia32_storeups (float *, v4sf)'
+ Generates the `movups' machine instruction as a store to memory.
+
+`v4sf __builtin_ia32_loadsss (float *)'
+ Generates the `movss' machine instruction as a load from memory.
+
+`void __builtin_ia32_storess (float *, v4sf)'
+ Generates the `movss' machine instruction as a store to memory.
+
+`v4sf __builtin_ia32_loadhps (v4sf, v2si *)'
+ Generates the `movhps' machine instruction as a load from memory.
+
+`v4sf __builtin_ia32_loadlps (v4sf, v2si *)'
+ Generates the `movlps' machine instruction as a load from memory
+
+`void __builtin_ia32_storehps (v4sf, v2si *)'
+ Generates the `movhps' machine instruction as a store to memory.
+
+`void __builtin_ia32_storelps (v4sf, v2si *)'
+ Generates the `movlps' machine instruction as a store to memory.
+
+ The following built-in functions are available when `-m3dnow' is
+used. All of them generate the machine instruction that is part of the
+name.
+
+ void __builtin_ia32_femms (void)
+ v8qi __builtin_ia32_pavgusb (v8qi, v8qi)
+ v2si __builtin_ia32_pf2id (v2sf)
+ v2sf __builtin_ia32_pfacc (v2sf, v2sf)
+ v2sf __builtin_ia32_pfadd (v2sf, v2sf)
+ v2si __builtin_ia32_pfcmpeq (v2sf, v2sf)
+ v2si __builtin_ia32_pfcmpge (v2sf, v2sf)
+ v2si __builtin_ia32_pfcmpgt (v2sf, v2sf)
+ v2sf __builtin_ia32_pfmax (v2sf, v2sf)
+ v2sf __builtin_ia32_pfmin (v2sf, v2sf)
+ v2sf __builtin_ia32_pfmul (v2sf, v2sf)
+ v2sf __builtin_ia32_pfrcp (v2sf)
+ v2sf __builtin_ia32_pfrcpit1 (v2sf, v2sf)
+ v2sf __builtin_ia32_pfrcpit2 (v2sf, v2sf)
+ v2sf __builtin_ia32_pfrsqrt (v2sf)
+ v2sf __builtin_ia32_pfrsqrtit1 (v2sf, v2sf)
+ v2sf __builtin_ia32_pfsub (v2sf, v2sf)
+ v2sf __builtin_ia32_pfsubr (v2sf, v2sf)
+ v2sf __builtin_ia32_pi2fd (v2si)
+ v4hi __builtin_ia32_pmulhrw (v4hi, v4hi)
+
+ The following built-in functions are available when both `-m3dnow'
+and `-march=athlon' are used. All of them generate the machine
+instruction that is part of the name.
+
+ v2si __builtin_ia32_pf2iw (v2sf)
+ v2sf __builtin_ia32_pfnacc (v2sf, v2sf)
+ v2sf __builtin_ia32_pfpnacc (v2sf, v2sf)
+ v2sf __builtin_ia32_pi2fw (v2si)
+ v2sf __builtin_ia32_pswapdsf (v2sf)
+ v2si __builtin_ia32_pswapdsi (v2si)
+
+\1f
+File: gcc.info, Node: PowerPC AltiVec Built-in Functions, Prev: X86 Built-in Functions, Up: Target Builtins
+
+5.45.2 PowerPC AltiVec Built-in Functions
+-----------------------------------------
+
+These built-in functions are available for the PowerPC family of
+computers, depending on the command-line switches used.
+
+ The following machine modes are available for use with AltiVec
+built-in functions (*note Vector Extensions::): `V4SI' for a vector of
+four 32-bit integers, `V4SF' for a vector of four 32-bit floating point
+numbers, `V8HI' for a vector of eight 16-bit integers, and `V16QI' for
+a vector of sixteen 8-bit integers.
+
+ The following functions are made available by including
+`<altivec.h>' and using `-maltivec' and `-mabi=altivec'. The functions
+implement the functionality described in Motorola's AltiVec Programming
+Interface Manual.
+
+ _Note:_ Only the `<altivec.h>' interface is supported. Internally,
+GCC uses built-in functions to achieve the functionality in the
+aforementioned header file, but they are not supported and are subject
+to change without notice.
+
+ vector signed char vec_abs (vector signed char, vector signed char);
+ vector signed short vec_abs (vector signed short, vector signed short);
+ vector signed int vec_abs (vector signed int, vector signed int);
+ vector signed float vec_abs (vector signed float, vector signed float);
+
+ vector signed char vec_abss (vector signed char, vector signed char);
+ vector signed short vec_abss (vector signed short, vector signed short);
+
+ vector signed char vec_add (vector signed char, vector signed char);
+ vector unsigned char vec_add (vector signed char, vector unsigned char);
+
+ vector unsigned char vec_add (vector unsigned char, vector signed char);
+
+ vector unsigned char vec_add (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_add (vector signed short, vector signed short);
+ vector unsigned short vec_add (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_add (vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_add (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_add (vector signed int, vector signed int);
+ vector unsigned int vec_add (vector signed int, vector unsigned int);
+ vector unsigned int vec_add (vector unsigned int, vector signed int);
+ vector unsigned int vec_add (vector unsigned int, vector unsigned int);
+ vector float vec_add (vector float, vector float);
+
+ vector unsigned int vec_addc (vector unsigned int, vector unsigned int);
+
+ vector unsigned char vec_adds (vector signed char,
+ vector unsigned char);
+ vector unsigned char vec_adds (vector unsigned char,
+ vector signed char);
+ vector unsigned char vec_adds (vector unsigned char,
+ vector unsigned char);
+ vector signed char vec_adds (vector signed char, vector signed char);
+ vector unsigned short vec_adds (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_adds (vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_adds (vector unsigned short,
+ vector unsigned short);
+ vector signed short vec_adds (vector signed short, vector signed short);
+
+ vector unsigned int vec_adds (vector signed int, vector unsigned int);
+ vector unsigned int vec_adds (vector unsigned int, vector signed int);
+ vector unsigned int vec_adds (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_adds (vector signed int, vector signed int);
+
+ vector float vec_and (vector float, vector float);
+ vector float vec_and (vector float, vector signed int);
+ vector float vec_and (vector signed int, vector float);
+ vector signed int vec_and (vector signed int, vector signed int);
+ vector unsigned int vec_and (vector signed int, vector unsigned int);
+ vector unsigned int vec_and (vector unsigned int, vector signed int);
+ vector unsigned int vec_and (vector unsigned int, vector unsigned int);
+ vector signed short vec_and (vector signed short, vector signed short);
+ vector unsigned short vec_and (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_and (vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_and (vector unsigned short,
+ vector unsigned short);
+ vector signed char vec_and (vector signed char, vector signed char);
+ vector unsigned char vec_and (vector signed char, vector unsigned char);
+
+ vector unsigned char vec_and (vector unsigned char, vector signed char);
+
+ vector unsigned char vec_and (vector unsigned char,
+ vector unsigned char);
+
+ vector float vec_andc (vector float, vector float);
+ vector float vec_andc (vector float, vector signed int);
+ vector float vec_andc (vector signed int, vector float);
+ vector signed int vec_andc (vector signed int, vector signed int);
+ vector unsigned int vec_andc (vector signed int, vector unsigned int);
+ vector unsigned int vec_andc (vector unsigned int, vector signed int);
+ vector unsigned int vec_andc (vector unsigned int, vector unsigned int);
+
+ vector signed short vec_andc (vector signed short, vector signed short);
+
+ vector unsigned short vec_andc (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_andc (vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_andc (vector unsigned short,
+ vector unsigned short);
+ vector signed char vec_andc (vector signed char, vector signed char);
+ vector unsigned char vec_andc (vector signed char,
+ vector unsigned char);
+ vector unsigned char vec_andc (vector unsigned char,
+ vector signed char);
+ vector unsigned char vec_andc (vector unsigned char,
+ vector unsigned char);
+
+ vector unsigned char vec_avg (vector unsigned char,
+ vector unsigned char);
+ vector signed char vec_avg (vector signed char, vector signed char);
+ vector unsigned short vec_avg (vector unsigned short,
+ vector unsigned short);
+ vector signed short vec_avg (vector signed short, vector signed short);
+ vector unsigned int vec_avg (vector unsigned int, vector unsigned int);
+ vector signed int vec_avg (vector signed int, vector signed int);
+
+ vector float vec_ceil (vector float);
+
+ vector signed int vec_cmpb (vector float, vector float);
+
+ vector signed char vec_cmpeq (vector signed char, vector signed char);
+ vector signed char vec_cmpeq (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_cmpeq (vector signed short,
+ vector signed short);
+ vector signed short vec_cmpeq (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_cmpeq (vector signed int, vector signed int);
+ vector signed int vec_cmpeq (vector unsigned int, vector unsigned int);
+ vector signed int vec_cmpeq (vector float, vector float);
+
+ vector signed int vec_cmpge (vector float, vector float);
+
+ vector signed char vec_cmpgt (vector unsigned char,
+ vector unsigned char);
+ vector signed char vec_cmpgt (vector signed char, vector signed char);
+ vector signed short vec_cmpgt (vector unsigned short,
+ vector unsigned short);
+ vector signed short vec_cmpgt (vector signed short,
+ vector signed short);
+ vector signed int vec_cmpgt (vector unsigned int, vector unsigned int);
+ vector signed int vec_cmpgt (vector signed int, vector signed int);
+ vector signed int vec_cmpgt (vector float, vector float);
+
+ vector signed int vec_cmple (vector float, vector float);
+
+ vector signed char vec_cmplt (vector unsigned char,
+ vector unsigned char);
+ vector signed char vec_cmplt (vector signed char, vector signed char);
+ vector signed short vec_cmplt (vector unsigned short,
+ vector unsigned short);
+ vector signed short vec_cmplt (vector signed short,
+ vector signed short);
+ vector signed int vec_cmplt (vector unsigned int, vector unsigned int);
+ vector signed int vec_cmplt (vector signed int, vector signed int);
+ vector signed int vec_cmplt (vector float, vector float);
+
+ vector float vec_ctf (vector unsigned int, const char);
+ vector float vec_ctf (vector signed int, const char);
+
+ vector signed int vec_cts (vector float, const char);
+
+ vector unsigned int vec_ctu (vector float, const char);
+
+ void vec_dss (const char);
+
+ void vec_dssall (void);
+
+ void vec_dst (void *, int, const char);
+
+ void vec_dstst (void *, int, const char);
+
+ void vec_dststt (void *, int, const char);
+
+ void vec_dstt (void *, int, const char);
+
+ vector float vec_expte (vector float, vector float);
+
+ vector float vec_floor (vector float, vector float);
+
+ vector float vec_ld (int, vector float *);
+ vector float vec_ld (int, float *):
+ vector signed int vec_ld (int, int *);
+ vector signed int vec_ld (int, vector signed int *);
+ vector unsigned int vec_ld (int, vector unsigned int *);
+ vector unsigned int vec_ld (int, unsigned int *);
+ vector signed short vec_ld (int, short *, vector signed short *);
+ vector unsigned short vec_ld (int, unsigned short *,
+ vector unsigned short *);
+ vector signed char vec_ld (int, signed char *);
+ vector signed char vec_ld (int, vector signed char *);
+ vector unsigned char vec_ld (int, unsigned char *);
+ vector unsigned char vec_ld (int, vector unsigned char *);
+
+ vector signed char vec_lde (int, signed char *);
+ vector unsigned char vec_lde (int, unsigned char *);
+ vector signed short vec_lde (int, short *);
+ vector unsigned short vec_lde (int, unsigned short *);
+ vector float vec_lde (int, float *);
+ vector signed int vec_lde (int, int *);
+ vector unsigned int vec_lde (int, unsigned int *);
+
+ void float vec_ldl (int, float *);
+ void float vec_ldl (int, vector float *);
+ void signed int vec_ldl (int, vector signed int *);
+ void signed int vec_ldl (int, int *);
+ void unsigned int vec_ldl (int, unsigned int *);
+ void unsigned int vec_ldl (int, vector unsigned int *);
+ void signed short vec_ldl (int, vector signed short *);
+ void signed short vec_ldl (int, short *);
+ void unsigned short vec_ldl (int, vector unsigned short *);
+ void unsigned short vec_ldl (int, unsigned short *);
+ void signed char vec_ldl (int, vector signed char *);
+ void signed char vec_ldl (int, signed char *);
+ void unsigned char vec_ldl (int, vector unsigned char *);
+ void unsigned char vec_ldl (int, unsigned char *);
+
+ vector float vec_loge (vector float);
+
+ vector unsigned char vec_lvsl (int, void *, int *);
+
+ vector unsigned char vec_lvsr (int, void *, int *);
+
+ vector float vec_madd (vector float, vector float, vector float);
+
+ vector signed short vec_madds (vector signed short, vector signed short,
+ vector signed short);
+
+ vector unsigned char vec_max (vector signed char, vector unsigned char);
+
+ vector unsigned char vec_max (vector unsigned char, vector signed char);
+
+ vector unsigned char vec_max (vector unsigned char,
+ vector unsigned char);
+ vector signed char vec_max (vector signed char, vector signed char);
+ vector unsigned short vec_max (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_max (vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_max (vector unsigned short,
+ vector unsigned short);
+ vector signed short vec_max (vector signed short, vector signed short);
+ vector unsigned int vec_max (vector signed int, vector unsigned int);
+ vector unsigned int vec_max (vector unsigned int, vector signed int);
+ vector unsigned int vec_max (vector unsigned int, vector unsigned int);
+ vector signed int vec_max (vector signed int, vector signed int);
+ vector float vec_max (vector float, vector float);
+
+ vector signed char vec_mergeh (vector signed char, vector signed char);
+ vector unsigned char vec_mergeh (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_mergeh (vector signed short,
+ vector signed short);
+ vector unsigned short vec_mergeh (vector unsigned short,
+ vector unsigned short);
+ vector float vec_mergeh (vector float, vector float);
+ vector signed int vec_mergeh (vector signed int, vector signed int);
+ vector unsigned int vec_mergeh (vector unsigned int,
+ vector unsigned int);
+
+ vector signed char vec_mergel (vector signed char, vector signed char);
+ vector unsigned char vec_mergel (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_mergel (vector signed short,
+ vector signed short);
+ vector unsigned short vec_mergel (vector unsigned short,
+ vector unsigned short);
+ vector float vec_mergel (vector float, vector float);
+ vector signed int vec_mergel (vector signed int, vector signed int);
+ vector unsigned int vec_mergel (vector unsigned int,
+ vector unsigned int);
+
+ vector unsigned short vec_mfvscr (void);
+
+ vector unsigned char vec_min (vector signed char, vector unsigned char);
+
+ vector unsigned char vec_min (vector unsigned char, vector signed char);
+
+ vector unsigned char vec_min (vector unsigned char,
+ vector unsigned char);
+ vector signed char vec_min (vector signed char, vector signed char);
+ vector unsigned short vec_min (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_min (vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_min (vector unsigned short,
+ vector unsigned short);
+ vector signed short vec_min (vector signed short, vector signed short);
+ vector unsigned int vec_min (vector signed int, vector unsigned int);
+ vector unsigned int vec_min (vector unsigned int, vector signed int);
+ vector unsigned int vec_min (vector unsigned int, vector unsigned int);
+ vector signed int vec_min (vector signed int, vector signed int);
+ vector float vec_min (vector float, vector float);
+
+ vector signed short vec_mladd (vector signed short, vector signed short,
+ vector signed short);
+ vector signed short vec_mladd (vector signed short,
+ vector unsigned short,
+ vector unsigned short);
+ vector signed short vec_mladd (vector unsigned short,
+ vector signed short,
+ vector signed short);
+ vector unsigned short vec_mladd (vector unsigned short,
+ vector unsigned short,
+ vector unsigned short);
+
+ vector signed short vec_mradds (vector signed short,
+ vector signed short,
+ vector signed short);
+
+ vector unsigned int vec_msum (vector unsigned char,
+ vector unsigned char,
+ vector unsigned int);
+ vector signed int vec_msum (vector signed char, vector unsigned char,
+ vector signed int);
+ vector unsigned int vec_msum (vector unsigned short,
+ vector unsigned short,
+ vector unsigned int);
+ vector signed int vec_msum (vector signed short, vector signed short,
+ vector signed int);
+
+ vector unsigned int vec_msums (vector unsigned short,
+ vector unsigned short,
+ vector unsigned int);
+ vector signed int vec_msums (vector signed short, vector signed short,
+ vector signed int);
+
+ void vec_mtvscr (vector signed int);
+ void vec_mtvscr (vector unsigned int);
+ void vec_mtvscr (vector signed short);
+ void vec_mtvscr (vector unsigned short);
+ void vec_mtvscr (vector signed char);
+ void vec_mtvscr (vector unsigned char);
+
+ vector unsigned short vec_mule (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_mule (vector signed char, vector signed char);
+ vector unsigned int vec_mule (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_mule (vector signed short, vector signed short);
+
+ vector unsigned short vec_mulo (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_mulo (vector signed char, vector signed char);
+ vector unsigned int vec_mulo (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_mulo (vector signed short, vector signed short);
+
+ vector float vec_nmsub (vector float, vector float, vector float);
+
+ vector float vec_nor (vector float, vector float);
+ vector signed int vec_nor (vector signed int, vector signed int);
+ vector unsigned int vec_nor (vector unsigned int, vector unsigned int);
+ vector signed short vec_nor (vector signed short, vector signed short);
+ vector unsigned short vec_nor (vector unsigned short,
+ vector unsigned short);
+ vector signed char vec_nor (vector signed char, vector signed char);
+ vector unsigned char vec_nor (vector unsigned char,
+ vector unsigned char);
+
+ vector float vec_or (vector float, vector float);
+ vector float vec_or (vector float, vector signed int);
+ vector float vec_or (vector signed int, vector float);
+ vector signed int vec_or (vector signed int, vector signed int);
+ vector unsigned int vec_or (vector signed int, vector unsigned int);
+ vector unsigned int vec_or (vector unsigned int, vector signed int);
+ vector unsigned int vec_or (vector unsigned int, vector unsigned int);
+ vector signed short vec_or (vector signed short, vector signed short);
+ vector unsigned short vec_or (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_or (vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_or (vector unsigned short,
+ vector unsigned short);
+ vector signed char vec_or (vector signed char, vector signed char);
+ vector unsigned char vec_or (vector signed char, vector unsigned char);
+ vector unsigned char vec_or (vector unsigned char, vector signed char);
+ vector unsigned char vec_or (vector unsigned char,
+ vector unsigned char);
+
+ vector signed char vec_pack (vector signed short, vector signed short);
+ vector unsigned char vec_pack (vector unsigned short,
+ vector unsigned short);
+ vector signed short vec_pack (vector signed int, vector signed int);
+ vector unsigned short vec_pack (vector unsigned int,
+ vector unsigned int);
+
+ vector signed short vec_packpx (vector unsigned int,
+ vector unsigned int);
+
+ vector unsigned char vec_packs (vector unsigned short,
+ vector unsigned short);
+ vector signed char vec_packs (vector signed short, vector signed short);
+
+ vector unsigned short vec_packs (vector unsigned int,
+ vector unsigned int);
+ vector signed short vec_packs (vector signed int, vector signed int);
+
+ vector unsigned char vec_packsu (vector unsigned short,
+ vector unsigned short);
+ vector unsigned char vec_packsu (vector signed short,
+ vector signed short);
+ vector unsigned short vec_packsu (vector unsigned int,
+ vector unsigned int);
+ vector unsigned short vec_packsu (vector signed int, vector signed int);
+
+ vector float vec_perm (vector float, vector float,
+ vector unsigned char);
+ vector signed int vec_perm (vector signed int, vector signed int,
+ vector unsigned char);
+ vector unsigned int vec_perm (vector unsigned int, vector unsigned int,
+ vector unsigned char);
+ vector signed short vec_perm (vector signed short, vector signed short,
+ vector unsigned char);
+ vector unsigned short vec_perm (vector unsigned short,
+ vector unsigned short,
+ vector unsigned char);
+ vector signed char vec_perm (vector signed char, vector signed char,
+ vector unsigned char);
+ vector unsigned char vec_perm (vector unsigned char,
+ vector unsigned char,
+ vector unsigned char);
+
+ vector float vec_re (vector float);
+
+ vector signed char vec_rl (vector signed char, vector unsigned char);
+ vector unsigned char vec_rl (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_rl (vector signed short, vector unsigned short);
+
+ vector unsigned short vec_rl (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_rl (vector signed int, vector unsigned int);
+ vector unsigned int vec_rl (vector unsigned int, vector unsigned int);
+
+ vector float vec_round (vector float);
+
+ vector float vec_rsqrte (vector float);
+
+ vector float vec_sel (vector float, vector float, vector signed int);
+ vector float vec_sel (vector float, vector float, vector unsigned int);
+ vector signed int vec_sel (vector signed int, vector signed int,
+ vector signed int);
+ vector signed int vec_sel (vector signed int, vector signed int,
+ vector unsigned int);
+ vector unsigned int vec_sel (vector unsigned int, vector unsigned int,
+ vector signed int);
+ vector unsigned int vec_sel (vector unsigned int, vector unsigned int,
+ vector unsigned int);
+ vector signed short vec_sel (vector signed short, vector signed short,
+ vector signed short);
+ vector signed short vec_sel (vector signed short, vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_sel (vector unsigned short,
+ vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_sel (vector unsigned short,
+ vector unsigned short,
+ vector unsigned short);
+ vector signed char vec_sel (vector signed char, vector signed char,
+ vector signed char);
+ vector signed char vec_sel (vector signed char, vector signed char,
+ vector unsigned char);
+ vector unsigned char vec_sel (vector unsigned char,
+ vector unsigned char,
+ vector signed char);
+ vector unsigned char vec_sel (vector unsigned char,
+ vector unsigned char,
+ vector unsigned char);
+
+ vector signed char vec_sl (vector signed char, vector unsigned char);
+ vector unsigned char vec_sl (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_sl (vector signed short, vector unsigned short);
+
+ vector unsigned short vec_sl (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_sl (vector signed int, vector unsigned int);
+ vector unsigned int vec_sl (vector unsigned int, vector unsigned int);
+
+ vector float vec_sld (vector float, vector float, const char);
+ vector signed int vec_sld (vector signed int, vector signed int,
+ const char);
+ vector unsigned int vec_sld (vector unsigned int, vector unsigned int,
+ const char);
+ vector signed short vec_sld (vector signed short, vector signed short,
+ const char);
+ vector unsigned short vec_sld (vector unsigned short,
+ vector unsigned short, const char);
+ vector signed char vec_sld (vector signed char, vector signed char,
+ const char);
+ vector unsigned char vec_sld (vector unsigned char,
+ vector unsigned char,
+ const char);
+
+ vector signed int vec_sll (vector signed int, vector unsigned int);
+ vector signed int vec_sll (vector signed int, vector unsigned short);
+ vector signed int vec_sll (vector signed int, vector unsigned char);
+ vector unsigned int vec_sll (vector unsigned int, vector unsigned int);
+ vector unsigned int vec_sll (vector unsigned int,
+ vector unsigned short);
+ vector unsigned int vec_sll (vector unsigned int, vector unsigned char);
+
+ vector signed short vec_sll (vector signed short, vector unsigned int);
+ vector signed short vec_sll (vector signed short,
+ vector unsigned short);
+ vector signed short vec_sll (vector signed short, vector unsigned char);
+
+ vector unsigned short vec_sll (vector unsigned short,
+ vector unsigned int);
+ vector unsigned short vec_sll (vector unsigned short,
+ vector unsigned short);
+ vector unsigned short vec_sll (vector unsigned short,
+ vector unsigned char);
+ vector signed char vec_sll (vector signed char, vector unsigned int);
+ vector signed char vec_sll (vector signed char, vector unsigned short);
+ vector signed char vec_sll (vector signed char, vector unsigned char);
+ vector unsigned char vec_sll (vector unsigned char,
+ vector unsigned int);
+ vector unsigned char vec_sll (vector unsigned char,
+ vector unsigned short);
+ vector unsigned char vec_sll (vector unsigned char,
+ vector unsigned char);
+
+ vector float vec_slo (vector float, vector signed char);
+ vector float vec_slo (vector float, vector unsigned char);
+ vector signed int vec_slo (vector signed int, vector signed char);
+ vector signed int vec_slo (vector signed int, vector unsigned char);
+ vector unsigned int vec_slo (vector unsigned int, vector signed char);
+ vector unsigned int vec_slo (vector unsigned int, vector unsigned char);
+
+ vector signed short vec_slo (vector signed short, vector signed char);
+ vector signed short vec_slo (vector signed short, vector unsigned char);
+
+ vector unsigned short vec_slo (vector unsigned short,
+ vector signed char);
+ vector unsigned short vec_slo (vector unsigned short,
+ vector unsigned char);
+ vector signed char vec_slo (vector signed char, vector signed char);
+ vector signed char vec_slo (vector signed char, vector unsigned char);
+ vector unsigned char vec_slo (vector unsigned char, vector signed char);
+
+ vector unsigned char vec_slo (vector unsigned char,
+ vector unsigned char);
+
+ vector signed char vec_splat (vector signed char, const char);
+ vector unsigned char vec_splat (vector unsigned char, const char);
+ vector signed short vec_splat (vector signed short, const char);
+ vector unsigned short vec_splat (vector unsigned short, const char);
+ vector float vec_splat (vector float, const char);
+ vector signed int vec_splat (vector signed int, const char);
+ vector unsigned int vec_splat (vector unsigned int, const char);
+
+ vector signed char vec_splat_s8 (const char);
+
+ vector signed short vec_splat_s16 (const char);
+
+ vector signed int vec_splat_s32 (const char);
+
+ vector unsigned char vec_splat_u8 (const char);
+
+ vector unsigned short vec_splat_u16 (const char);
+
+ vector unsigned int vec_splat_u32 (const char);
+
+ vector signed char vec_sr (vector signed char, vector unsigned char);
+ vector unsigned char vec_sr (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_sr (vector signed short, vector unsigned short);
+
+ vector unsigned short vec_sr (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_sr (vector signed int, vector unsigned int);
+ vector unsigned int vec_sr (vector unsigned int, vector unsigned int);
+
+ vector signed char vec_sra (vector signed char, vector unsigned char);
+ vector unsigned char vec_sra (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_sra (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_sra (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_sra (vector signed int, vector unsigned int);
+ vector unsigned int vec_sra (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_srl (vector signed int, vector unsigned int);
+ vector signed int vec_srl (vector signed int, vector unsigned short);
+ vector signed int vec_srl (vector signed int, vector unsigned char);
+ vector unsigned int vec_srl (vector unsigned int, vector unsigned int);
+ vector unsigned int vec_srl (vector unsigned int,
+ vector unsigned short);
+ vector unsigned int vec_srl (vector unsigned int, vector unsigned char);
+
+ vector signed short vec_srl (vector signed short, vector unsigned int);
+ vector signed short vec_srl (vector signed short,
+ vector unsigned short);
+ vector signed short vec_srl (vector signed short, vector unsigned char);
+
+ vector unsigned short vec_srl (vector unsigned short,
+ vector unsigned int);
+ vector unsigned short vec_srl (vector unsigned short,
+ vector unsigned short);
+ vector unsigned short vec_srl (vector unsigned short,
+ vector unsigned char);
+ vector signed char vec_srl (vector signed char, vector unsigned int);
+ vector signed char vec_srl (vector signed char, vector unsigned short);
+ vector signed char vec_srl (vector signed char, vector unsigned char);
+ vector unsigned char vec_srl (vector unsigned char,
+ vector unsigned int);
+ vector unsigned char vec_srl (vector unsigned char,
+ vector unsigned short);
+ vector unsigned char vec_srl (vector unsigned char,
+ vector unsigned char);
+
+ vector float vec_sro (vector float, vector signed char);
+ vector float vec_sro (vector float, vector unsigned char);
+ vector signed int vec_sro (vector signed int, vector signed char);
+ vector signed int vec_sro (vector signed int, vector unsigned char);
+ vector unsigned int vec_sro (vector unsigned int, vector signed char);
+ vector unsigned int vec_sro (vector unsigned int, vector unsigned char);
+
+ vector signed short vec_sro (vector signed short, vector signed char);
+ vector signed short vec_sro (vector signed short, vector unsigned char);
+
+ vector unsigned short vec_sro (vector unsigned short,
+ vector signed char);
+ vector unsigned short vec_sro (vector unsigned short,
+ vector unsigned char);
+ vector signed char vec_sro (vector signed char, vector signed char);
+ vector signed char vec_sro (vector signed char, vector unsigned char);
+ vector unsigned char vec_sro (vector unsigned char, vector signed char);
+
+ vector unsigned char vec_sro (vector unsigned char,
+ vector unsigned char);
+
+ void vec_st (vector float, int, float *);
+ void vec_st (vector float, int, vector float *);
+ void vec_st (vector signed int, int, int *);
+ void vec_st (vector signed int, int, unsigned int *);
+ void vec_st (vector unsigned int, int, unsigned int *);
+ void vec_st (vector unsigned int, int, vector unsigned int *);
+ void vec_st (vector signed short, int, short *);
+ void vec_st (vector signed short, int, vector unsigned short *);
+ void vec_st (vector signed short, int, vector signed short *);
+ void vec_st (vector unsigned short, int, unsigned short *);
+ void vec_st (vector unsigned short, int, vector unsigned short *);
+ void vec_st (vector signed char, int, signed char *);
+ void vec_st (vector signed char, int, unsigned char *);
+ void vec_st (vector signed char, int, vector signed char *);
+ void vec_st (vector unsigned char, int, unsigned char *);
+ void vec_st (vector unsigned char, int, vector unsigned char *);
+
+ void vec_ste (vector signed char, int, unsigned char *);
+ void vec_ste (vector signed char, int, signed char *);
+ void vec_ste (vector unsigned char, int, unsigned char *);
+ void vec_ste (vector signed short, int, short *);
+ void vec_ste (vector signed short, int, unsigned short *);
+ void vec_ste (vector unsigned short, int, void *);
+ void vec_ste (vector signed int, int, unsigned int *);
+ void vec_ste (vector signed int, int, int *);
+ void vec_ste (vector unsigned int, int, unsigned int *);
+ void vec_ste (vector float, int, float *);
+
+ void vec_stl (vector float, int, vector float *);
+ void vec_stl (vector float, int, float *);
+ void vec_stl (vector signed int, int, vector signed int *);
+ void vec_stl (vector signed int, int, int *);
+ void vec_stl (vector signed int, int, unsigned int *);
+ void vec_stl (vector unsigned int, int, vector unsigned int *);
+ void vec_stl (vector unsigned int, int, unsigned int *);
+ void vec_stl (vector signed short, int, short *);
+ void vec_stl (vector signed short, int, unsigned short *);
+ void vec_stl (vector signed short, int, vector signed short *);
+ void vec_stl (vector unsigned short, int, unsigned short *);
+ void vec_stl (vector unsigned short, int, vector signed short *);
+ void vec_stl (vector signed char, int, signed char *);
+ void vec_stl (vector signed char, int, unsigned char *);
+ void vec_stl (vector signed char, int, vector signed char *);
+ void vec_stl (vector unsigned char, int, unsigned char *);
+ void vec_stl (vector unsigned char, int, vector unsigned char *);
+
+ vector signed char vec_sub (vector signed char, vector signed char);
+ vector unsigned char vec_sub (vector signed char, vector unsigned char);
+
+ vector unsigned char vec_sub (vector unsigned char, vector signed char);
+
+ vector unsigned char vec_sub (vector unsigned char,
+ vector unsigned char);
+ vector signed short vec_sub (vector signed short, vector signed short);
+ vector unsigned short vec_sub (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_sub (vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_sub (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_sub (vector signed int, vector signed int);
+ vector unsigned int vec_sub (vector signed int, vector unsigned int);
+ vector unsigned int vec_sub (vector unsigned int, vector signed int);
+ vector unsigned int vec_sub (vector unsigned int, vector unsigned int);
+ vector float vec_sub (vector float, vector float);
+
+ vector unsigned int vec_subc (vector unsigned int, vector unsigned int);
+
+ vector unsigned char vec_subs (vector signed char,
+ vector unsigned char);
+ vector unsigned char vec_subs (vector unsigned char,
+ vector signed char);
+ vector unsigned char vec_subs (vector unsigned char,
+ vector unsigned char);
+ vector signed char vec_subs (vector signed char, vector signed char);
+ vector unsigned short vec_subs (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_subs (vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_subs (vector unsigned short,
+ vector unsigned short);
+ vector signed short vec_subs (vector signed short, vector signed short);
+
+ vector unsigned int vec_subs (vector signed int, vector unsigned int);
+ vector unsigned int vec_subs (vector unsigned int, vector signed int);
+ vector unsigned int vec_subs (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_subs (vector signed int, vector signed int);
+
+ vector unsigned int vec_sum4s (vector unsigned char,
+ vector unsigned int);
+ vector signed int vec_sum4s (vector signed char, vector signed int);
+ vector signed int vec_sum4s (vector signed short, vector signed int);
+
+ vector signed int vec_sum2s (vector signed int, vector signed int);
+
+ vector signed int vec_sums (vector signed int, vector signed int);
+
+ vector float vec_trunc (vector float);
+
+ vector signed short vec_unpackh (vector signed char);
+ vector unsigned int vec_unpackh (vector signed short);
+ vector signed int vec_unpackh (vector signed short);
+
+ vector signed short vec_unpackl (vector signed char);
+ vector unsigned int vec_unpackl (vector signed short);
+ vector signed int vec_unpackl (vector signed short);
+
+ vector float vec_xor (vector float, vector float);
+ vector float vec_xor (vector float, vector signed int);
+ vector float vec_xor (vector signed int, vector float);
+ vector signed int vec_xor (vector signed int, vector signed int);
+ vector unsigned int vec_xor (vector signed int, vector unsigned int);
+ vector unsigned int vec_xor (vector unsigned int, vector signed int);
+ vector unsigned int vec_xor (vector unsigned int, vector unsigned int);
+ vector signed short vec_xor (vector signed short, vector signed short);
+ vector unsigned short vec_xor (vector signed short,
+ vector unsigned short);
+ vector unsigned short vec_xor (vector unsigned short,
+ vector signed short);
+ vector unsigned short vec_xor (vector unsigned short,
+ vector unsigned short);
+ vector signed char vec_xor (vector signed char, vector signed char);
+ vector unsigned char vec_xor (vector signed char, vector unsigned char);
+
+ vector unsigned char vec_xor (vector unsigned char, vector signed char);
+
+ vector unsigned char vec_xor (vector unsigned char,
+ vector unsigned char);
+
+ vector signed int vec_all_eq (vector signed char, vector unsigned char);
+
+ vector signed int vec_all_eq (vector signed char, vector signed char);
+ vector signed int vec_all_eq (vector unsigned char, vector signed char);
+
+ vector signed int vec_all_eq (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_all_eq (vector signed short,
+ vector unsigned short);
+ vector signed int vec_all_eq (vector signed short, vector signed short);
+
+ vector signed int vec_all_eq (vector unsigned short,
+ vector signed short);
+ vector signed int vec_all_eq (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_all_eq (vector signed int, vector unsigned int);
+ vector signed int vec_all_eq (vector signed int, vector signed int);
+ vector signed int vec_all_eq (vector unsigned int, vector signed int);
+ vector signed int vec_all_eq (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_all_eq (vector float, vector float);
+
+ vector signed int vec_all_ge (vector signed char, vector unsigned char);
+
+ vector signed int vec_all_ge (vector unsigned char, vector signed char);
+
+ vector signed int vec_all_ge (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_all_ge (vector signed char, vector signed char);
+ vector signed int vec_all_ge (vector signed short,
+ vector unsigned short);
+ vector signed int vec_all_ge (vector unsigned short,
+ vector signed short);
+ vector signed int vec_all_ge (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_all_ge (vector signed short, vector signed short);
+
+ vector signed int vec_all_ge (vector signed int, vector unsigned int);
+ vector signed int vec_all_ge (vector unsigned int, vector signed int);
+ vector signed int vec_all_ge (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_all_ge (vector signed int, vector signed int);
+ vector signed int vec_all_ge (vector float, vector float);
+
+ vector signed int vec_all_gt (vector signed char, vector unsigned char);
+
+ vector signed int vec_all_gt (vector unsigned char, vector signed char);
+
+ vector signed int vec_all_gt (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_all_gt (vector signed char, vector signed char);
+ vector signed int vec_all_gt (vector signed short,
+ vector unsigned short);
+ vector signed int vec_all_gt (vector unsigned short,
+ vector signed short);
+ vector signed int vec_all_gt (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_all_gt (vector signed short, vector signed short);
+
+ vector signed int vec_all_gt (vector signed int, vector unsigned int);
+ vector signed int vec_all_gt (vector unsigned int, vector signed int);
+ vector signed int vec_all_gt (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_all_gt (vector signed int, vector signed int);
+ vector signed int vec_all_gt (vector float, vector float);
+
+ vector signed int vec_all_in (vector float, vector float);
+
+ vector signed int vec_all_le (vector signed char, vector unsigned char);
+
+ vector signed int vec_all_le (vector unsigned char, vector signed char);
+
+ vector signed int vec_all_le (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_all_le (vector signed char, vector signed char);
+ vector signed int vec_all_le (vector signed short,
+ vector unsigned short);
+ vector signed int vec_all_le (vector unsigned short,
+ vector signed short);
+ vector signed int vec_all_le (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_all_le (vector signed short, vector signed short);
+
+ vector signed int vec_all_le (vector signed int, vector unsigned int);
+ vector signed int vec_all_le (vector unsigned int, vector signed int);
+ vector signed int vec_all_le (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_all_le (vector signed int, vector signed int);
+ vector signed int vec_all_le (vector float, vector float);
+
+ vector signed int vec_all_lt (vector signed char, vector unsigned char);
+
+ vector signed int vec_all_lt (vector unsigned char, vector signed char);
+
+ vector signed int vec_all_lt (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_all_lt (vector signed char, vector signed char);
+ vector signed int vec_all_lt (vector signed short,
+ vector unsigned short);
+ vector signed int vec_all_lt (vector unsigned short,
+ vector signed short);
+ vector signed int vec_all_lt (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_all_lt (vector signed short, vector signed short);
+
+ vector signed int vec_all_lt (vector signed int, vector unsigned int);
+ vector signed int vec_all_lt (vector unsigned int, vector signed int);
+ vector signed int vec_all_lt (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_all_lt (vector signed int, vector signed int);
+ vector signed int vec_all_lt (vector float, vector float);
+
+ vector signed int vec_all_nan (vector float);
+
+ vector signed int vec_all_ne (vector signed char, vector unsigned char);
+
+ vector signed int vec_all_ne (vector signed char, vector signed char);
+ vector signed int vec_all_ne (vector unsigned char, vector signed char);
+
+ vector signed int vec_all_ne (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_all_ne (vector signed short,
+ vector unsigned short);
+ vector signed int vec_all_ne (vector signed short, vector signed short);
+
+ vector signed int vec_all_ne (vector unsigned short,
+ vector signed short);
+ vector signed int vec_all_ne (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_all_ne (vector signed int, vector unsigned int);
+ vector signed int vec_all_ne (vector signed int, vector signed int);
+ vector signed int vec_all_ne (vector unsigned int, vector signed int);
+ vector signed int vec_all_ne (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_all_ne (vector float, vector float);
+
+ vector signed int vec_all_nge (vector float, vector float);
+
+ vector signed int vec_all_ngt (vector float, vector float);
+
+ vector signed int vec_all_nle (vector float, vector float);
+
+ vector signed int vec_all_nlt (vector float, vector float);
+
+ vector signed int vec_all_numeric (vector float);
+
+ vector signed int vec_any_eq (vector signed char, vector unsigned char);
+
+ vector signed int vec_any_eq (vector signed char, vector signed char);
+ vector signed int vec_any_eq (vector unsigned char, vector signed char);
+
+ vector signed int vec_any_eq (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_any_eq (vector signed short,
+ vector unsigned short);
+ vector signed int vec_any_eq (vector signed short, vector signed short);
+
+ vector signed int vec_any_eq (vector unsigned short,
+ vector signed short);
+ vector signed int vec_any_eq (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_any_eq (vector signed int, vector unsigned int);
+ vector signed int vec_any_eq (vector signed int, vector signed int);
+ vector signed int vec_any_eq (vector unsigned int, vector signed int);
+ vector signed int vec_any_eq (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_any_eq (vector float, vector float);
+
+ vector signed int vec_any_ge (vector signed char, vector unsigned char);
+
+ vector signed int vec_any_ge (vector unsigned char, vector signed char);
+
+ vector signed int vec_any_ge (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_any_ge (vector signed char, vector signed char);
+ vector signed int vec_any_ge (vector signed short,
+ vector unsigned short);
+ vector signed int vec_any_ge (vector unsigned short,
+ vector signed short);
+ vector signed int vec_any_ge (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_any_ge (vector signed short, vector signed short);
+
+ vector signed int vec_any_ge (vector signed int, vector unsigned int);
+ vector signed int vec_any_ge (vector unsigned int, vector signed int);
+ vector signed int vec_any_ge (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_any_ge (vector signed int, vector signed int);
+ vector signed int vec_any_ge (vector float, vector float);
+
+ vector signed int vec_any_gt (vector signed char, vector unsigned char);
+
+ vector signed int vec_any_gt (vector unsigned char, vector signed char);
+
+ vector signed int vec_any_gt (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_any_gt (vector signed char, vector signed char);
+ vector signed int vec_any_gt (vector signed short,
+ vector unsigned short);
+ vector signed int vec_any_gt (vector unsigned short,
+ vector signed short);
+ vector signed int vec_any_gt (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_any_gt (vector signed short, vector signed short);
+
+ vector signed int vec_any_gt (vector signed int, vector unsigned int);
+ vector signed int vec_any_gt (vector unsigned int, vector signed int);
+ vector signed int vec_any_gt (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_any_gt (vector signed int, vector signed int);
+ vector signed int vec_any_gt (vector float, vector float);
+
+ vector signed int vec_any_le (vector signed char, vector unsigned char);
+
+ vector signed int vec_any_le (vector unsigned char, vector signed char);
+
+ vector signed int vec_any_le (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_any_le (vector signed char, vector signed char);
+ vector signed int vec_any_le (vector signed short,
+ vector unsigned short);
+ vector signed int vec_any_le (vector unsigned short,
+ vector signed short);
+ vector signed int vec_any_le (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_any_le (vector signed short, vector signed short);
+
+ vector signed int vec_any_le (vector signed int, vector unsigned int);
+ vector signed int vec_any_le (vector unsigned int, vector signed int);
+ vector signed int vec_any_le (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_any_le (vector signed int, vector signed int);
+ vector signed int vec_any_le (vector float, vector float);
+
+ vector signed int vec_any_lt (vector signed char, vector unsigned char);
+
+ vector signed int vec_any_lt (vector unsigned char, vector signed char);
+
+ vector signed int vec_any_lt (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_any_lt (vector signed char, vector signed char);
+ vector signed int vec_any_lt (vector signed short,
+ vector unsigned short);
+ vector signed int vec_any_lt (vector unsigned short,
+ vector signed short);
+ vector signed int vec_any_lt (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_any_lt (vector signed short, vector signed short);
+
+ vector signed int vec_any_lt (vector signed int, vector unsigned int);
+ vector signed int vec_any_lt (vector unsigned int, vector signed int);
+ vector signed int vec_any_lt (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_any_lt (vector signed int, vector signed int);
+ vector signed int vec_any_lt (vector float, vector float);
+
+ vector signed int vec_any_nan (vector float);
+
+ vector signed int vec_any_ne (vector signed char, vector unsigned char);
+
+ vector signed int vec_any_ne (vector signed char, vector signed char);
+ vector signed int vec_any_ne (vector unsigned char, vector signed char);
+
+ vector signed int vec_any_ne (vector unsigned char,
+ vector unsigned char);
+ vector signed int vec_any_ne (vector signed short,
+ vector unsigned short);
+ vector signed int vec_any_ne (vector signed short, vector signed short);
+
+ vector signed int vec_any_ne (vector unsigned short,
+ vector signed short);
+ vector signed int vec_any_ne (vector unsigned short,
+ vector unsigned short);
+ vector signed int vec_any_ne (vector signed int, vector unsigned int);
+ vector signed int vec_any_ne (vector signed int, vector signed int);
+ vector signed int vec_any_ne (vector unsigned int, vector signed int);
+ vector signed int vec_any_ne (vector unsigned int, vector unsigned int);
+
+ vector signed int vec_any_ne (vector float, vector float);
+
+ vector signed int vec_any_nge (vector float, vector float);
+
+ vector signed int vec_any_ngt (vector float, vector float);
+
+ vector signed int vec_any_nle (vector float, vector float);
+
+ vector signed int vec_any_nlt (vector float, vector float);
+
+ vector signed int vec_any_numeric (vector float);
+
+ vector signed int vec_any_out (vector float, vector float);
+
+\1f
+File: gcc.info, Node: Pragmas, Next: Unnamed Fields, Prev: Target Builtins, Up: C Extensions
+
+5.46 Pragmas Accepted by GCC
+============================
+
+GCC supports several types of pragmas, primarily in order to compile
+code originally written for other compilers. Note that in general we
+do not recommend the use of pragmas; *Note Function Attributes::, for
+further explanation.
+
+* Menu:
+
+* ARM Pragmas::
+* Darwin Pragmas::
+* Solaris Pragmas::
+* Tru64 Pragmas::
+
+\1f
+File: gcc.info, Node: ARM Pragmas, Next: Darwin Pragmas, Up: Pragmas
+
+5.46.1 ARM Pragmas
+------------------
+
+The ARM target defines pragmas for controlling the default addition of
+`long_call' and `short_call' attributes to functions. *Note Function
+Attributes::, for information about the effects of these attributes.
+
+`long_calls'
+ Set all subsequent functions to have the `long_call' attribute.
+
+`no_long_calls'
+ Set all subsequent functions to have the `short_call' attribute.
+
+`long_calls_off'
+ Do not affect the `long_call' or `short_call' attributes of
+ subsequent functions.
+
+\1f
+File: gcc.info, Node: Darwin Pragmas, Next: Solaris Pragmas, Prev: ARM Pragmas, Up: Pragmas
+
+5.46.2 Darwin Pragmas
+---------------------
+
+The following pragmas are available for all architectures running the
+Darwin operating system. These are useful for compatibility with other
+MacOS compilers.
+
+`mark TOKENS...'
+ This pragma is accepted, but has no effect.
+
+`options align=ALIGNMENT'
+ This pragma sets the alignment of fields in structures. The
+ values of ALIGNMENT may be `mac68k', to emulate m68k alignment, or
+ `power', to emulate PowerPC alignment. Uses of this pragma nest
+ properly; to restore the previous setting, use `reset' for the
+ ALIGNMENT.
+
+`segment TOKENS...'
+ This pragma is accepted, but has no effect.
+
+`unused (VAR [, VAR]...)'
+ This pragma declares variables to be possibly unused. GCC will not
+ produce warnings for the listed variables. The effect is similar
+ to that of the `unused' attribute, except that this pragma may
+ appear anywhere within the variables' scopes.
+
+\1f
+File: gcc.info, Node: Solaris Pragmas, Next: Tru64 Pragmas, Prev: Darwin Pragmas, Up: Pragmas
+
+5.46.3 Solaris Pragmas
+----------------------
+
+For compatibility with the SunPRO compiler, the following pragma is
+supported.
+
+`redefine_extname OLDNAME NEWNAME'
+ This pragma gives the C function OLDNAME the assembler label
+ NEWNAME. The pragma must appear before the function declaration.
+ This pragma is equivalent to the asm labels extension (*note Asm
+ Labels::). The preprocessor defines `__PRAGMA_REDEFINE_EXTNAME'
+ if the pragma is available.
+
+\1f
+File: gcc.info, Node: Tru64 Pragmas, Prev: Solaris Pragmas, Up: Pragmas
+
+5.46.4 Tru64 Pragmas
+--------------------
+
+For compatibility with the Compaq C compiler, the following pragma is
+supported.
+
+`extern_prefix STRING'
+ This pragma renames all subsequent function and variable
+ declarations such that STRING is prepended to the name. This
+ effect may be terminated by using another `extern_prefix' pragma
+ with the empty string.
+
+ This pragma is similar in intent to to the asm labels extension
+ (*note Asm Labels::) in that the system programmer wants to change
+ the assembly-level ABI without changing the source-level API. The
+ preprocessor defines `__PRAGMA_EXTERN_PREFIX' if the pragma is
+ available.
+
+\1f
+File: gcc.info, Node: Unnamed Fields, Prev: Pragmas, Up: C Extensions
+
+5.47 Unnamed struct/union fields within structs/unions.
+=======================================================
+
+For compatibility with other compilers, GCC allows you to define a
+structure or union that contains, as fields, structures and unions
+without names. For example:
+
+ struct {
+ int a;
+ union {
+ int b;
+ float c;
+ };
+ int d;
+ } foo;
+
+ In this example, the user would be able to access members of the
+unnamed union with code like `foo.b'. Note that only unnamed structs
+and unions are allowed, you may not have, for example, an unnamed `int'.
+
+ You must never create such structures that cause ambiguous field
+definitions. For example, this structure:
+
+ struct {
+ int a;
+ struct {
+ int a;
+ };
+ } foo;
+
+ It is ambiguous which `a' is being referred to with `foo.a'. Such
+constructs are not supported and must be avoided. In the future, such
+constructs may be detected and treated as compilation errors.
+
+\1f
+File: gcc.info, Node: C++ Extensions, Next: Objective-C, Prev: C Extensions, Up: Top
+
+6 Extensions to the C++ Language
+********************************
+
+The GNU compiler provides these extensions to the C++ language (and you
+can also use most of the C language extensions in your C++ programs).
+If you want to write code that checks whether these features are
+available, you can test for the GNU compiler the same way as for C
+programs: check for a predefined macro `__GNUC__'. You can also use
+`__GNUG__' to test specifically for GNU C++ (*note Standard Predefined
+Macros: (cpp.info)Standard Predefined.).
+
+* Menu:
+
+* Min and Max:: C++ Minimum and maximum operators.
+* Volatiles:: What constitutes an access to a volatile object.
+* Restricted Pointers:: C99 restricted pointers and references.
+* Vague Linkage:: Where G++ puts inlines, vtables and such.
+* C++ Interface:: You can use a single C++ header file for both
+ declarations and definitions.
+* Template Instantiation:: Methods for ensuring that exactly one copy of
+ each needed template instantiation is emitted.
+* Bound member functions:: You can extract a function pointer to the
+ method denoted by a `->*' or `.*' expression.
+* C++ Attributes:: Variable, function, and type attributes for C++ only.
+* Java Exceptions:: Tweaking exception handling to work with Java.
+* Deprecated Features:: Things might disappear from g++.
+* Backwards Compatibility:: Compatibilities with earlier definitions of C++.
+
+\1f
+File: gcc.info, Node: Min and Max, Next: Volatiles, Up: C++ Extensions
+
+6.1 Minimum and Maximum Operators in C++
+========================================
+
+It is very convenient to have operators which return the "minimum" or
+the "maximum" of two arguments. In GNU C++ (but not in GNU C),
+
+`A <? B'
+ is the "minimum", returning the smaller of the numeric values A
+ and B;
+
+`A >? B'
+ is the "maximum", returning the larger of the numeric values A and
+ B.
+
+ These operations are not primitive in ordinary C++, since you can
+use a macro to return the minimum of two things in C++, as in the
+following example.
+
+ #define MIN(X,Y) ((X) < (Y) ? : (X) : (Y))
+
+You might then use `int min = MIN (i, j);' to set MIN to the minimum
+value of variables I and J.
-Options to Request or Suppress Warnings
+ However, side effects in `X' or `Y' may cause unintended behavior.
+For example, `MIN (i++, j++)' will fail, incrementing the smaller
+counter twice. The GNU C `typeof' extension allows you to write safe
+macros that avoid this kind of problem (*note Typeof::). However,
+writing `MIN' and `MAX' as macros also forces you to use function-call
+notation for a fundamental arithmetic operation. Using GNU C++
+extensions, you can write `int min = i <? j;' instead.
+
+ Since `<?' and `>?' are built into the compiler, they properly
+handle expressions with side-effects; `int min = i++ <? j++;' works
+correctly.
+
+\1f
+File: gcc.info, Node: Volatiles, Next: Restricted Pointers, Prev: Min and Max, Up: C++ Extensions
+
+6.2 When is a Volatile Object Accessed?
=======================================
- Warnings are diagnostic messages that report constructions which are
-not inherently erroneous but which are risky or suggest there may have
-been an error.
-
- You can request many specific warnings with options beginning `-W',
-for example `-Wimplicit' to request warnings on implicit declarations.
-Each of these specific warning options also has a negative form
-beginning `-Wno-' to turn off warnings; for example, `-Wno-implicit'.
-This manual lists only one of the two forms, whichever is not the
-default.
-
- The following options control the amount and kinds of warnings
-produced by GCC; for further, language-specific options also refer to
-*Note C++ Dialect Options:: and *Note Objective-C Dialect Options::.
-
-`-fsyntax-only'
- Check the code for syntax errors, but don't do anything beyond
- that.
-
-`-pedantic'
- Issue all the warnings demanded by strict ISO C and ISO C++;
- reject all programs that use forbidden extensions, and some other
- programs that do not follow ISO C and ISO C++. For ISO C, follows
- the version of the ISO C standard specified by any `-std' option
- used.
-
- Valid ISO C and ISO C++ programs should compile properly with or
- without this option (though a rare few will require `-ansi' or a
- `-std' option specifying the required version of ISO C). However,
- without this option, certain GNU extensions and traditional C and
- C++ features are supported as well. With this option, they are
- rejected.
-
- `-pedantic' does not cause warning messages for use of the
- alternate keywords whose names begin and end with `__'. Pedantic
- warnings are also disabled in the expression that follows
- `__extension__'. However, only system header files should use
- these escape routes; application programs should avoid them.
- *Note Alternate Keywords::.
-
- Some users try to use `-pedantic' to check programs for strict ISO
- C conformance. They soon find that it does not do quite what they
- want: it finds some non-ISO practices, but not all--only those for
- which ISO C _requires_ a diagnostic, and some others for which
- diagnostics have been added.
-
- A feature to report any failure to conform to ISO C might be
- useful in some instances, but would require considerable
- additional work and would be quite different from `-pedantic'. We
- don't have plans to support such a feature in the near future.
-
- Where the standard specified with `-std' represents a GNU extended
- dialect of C, such as `gnu89' or `gnu99', there is a corresponding
- "base standard", the version of ISO C on which the GNU extended
- dialect is based. Warnings from `-pedantic' are given where they
- are required by the base standard. (It would not make sense for
- such warnings to be given only for features not in the specified
- GNU C dialect, since by definition the GNU dialects of C include
- all features the compiler supports with the given option, and
- there would be nothing to warn about.)
-
-`-pedantic-errors'
- Like `-pedantic', except that errors are produced rather than
- warnings.
-
-`-w'
- Inhibit all warning messages.
-
-`-Wno-import'
- Inhibit warning messages about the use of `#import'.
-
-`-Wchar-subscripts'
- Warn if an array subscript has type `char'. This is a common cause
- of error, as programmers often forget that this type is signed on
- some machines.
-
-`-Wcomment'
- Warn whenever a comment-start sequence `/*' appears in a `/*'
- comment, or whenever a Backslash-Newline appears in a `//' comment.
-
-`-Wformat'
- Check calls to `printf' and `scanf', etc., to make sure that the
- arguments supplied have types appropriate to the format string
- specified, and that the conversions specified in the format string
- make sense. This includes standard functions, and others
- specified by format attributes (*note Function Attributes::), in
- the `printf', `scanf', `strftime' and `strfmon' (an X/Open
- extension, not in the C standard) families.
-
- The formats are checked against the format features supported by
- GNU libc version 2.2. These include all ISO C89 and C99 features,
- as well as features from the Single Unix Specification and some
- BSD and GNU extensions. Other library implementations may not
- support all these features; GCC does not support warning about
- features that go beyond a particular library's limitations.
- However, if `-pedantic' is used with `-Wformat', warnings will be
- given about format features not in the selected standard version
- (but not for `strfmon' formats, since those are not in any version
- of the C standard). *Note Options Controlling C Dialect: C
- Dialect Options.
-
- `-Wformat' is included in `-Wall'. For more control over some
- aspects of format checking, the options `-Wno-format-y2k',
- `-Wno-format-extra-args', `-Wformat-nonliteral',
- `-Wformat-security' and `-Wformat=2' are available, but are not
- included in `-Wall'.
-
-`-Wno-format-y2k'
- If `-Wformat' is specified, do not warn about `strftime' formats
- which may yield only a two-digit year.
-
-`-Wno-format-extra-args'
- If `-Wformat' is specified, do not warn about excess arguments to a
- `printf' or `scanf' format function. The C standard specifies
- that such arguments are ignored.
-
- Where the unused arguments lie between used arguments that are
- specified with `$' operand number specifications, normally
- warnings are still given, since the implementation could not know
- what type to pass to `va_arg' to skip the unused arguments.
- However, in the case of `scanf' formats, this option will suppress
- the warning if the unused arguments are all pointers, since the
- Single Unix Specification says that such unused arguments are
- allowed.
-
-`-Wformat-nonliteral'
- If `-Wformat' is specified, also warn if the format string is not a
- string literal and so cannot be checked, unless the format function
- takes its format arguments as a `va_list'.
-
-`-Wformat-security'
- If `-Wformat' is specified, also warn about uses of format
- functions that represent possible security problems. At present,
- this warns about calls to `printf' and `scanf' functions where the
- format string is not a string literal and there are no format
- arguments, as in `printf (foo);'. This may be a security hole if
- the format string came from untrusted input and contains `%n'.
- (This is currently a subset of what `-Wformat-nonliteral' warns
- about, but in future warnings may be added to `-Wformat-security'
- that are not included in `-Wformat-nonliteral'.)
-
-`-Wformat=2'
- Enable `-Wformat' plus format checks not included in `-Wformat'.
- Currently equivalent to `-Wformat -Wformat-nonliteral
- -Wformat-security'.
-
-`-Wimplicit-int'
- Warn when a declaration does not specify a type.
-
-`-Wimplicit-function-declaration'
-`-Werror-implicit-function-declaration'
- Give a warning (or error) whenever a function is used before being
- declared.
-
-`-Wimplicit'
- Same as `-Wimplicit-int' and `-Wimplicit-function-declaration'.
-
-`-Wmain'
- Warn if the type of `main' is suspicious. `main' should be a
- function with external linkage, returning int, taking either zero
- arguments, two, or three arguments of appropriate types.
-
-`-Wmissing-braces'
- Warn if an aggregate or union initializer is not fully bracketed.
- In the following example, the initializer for `a' is not fully
- bracketed, but that for `b' is fully bracketed.
-
- int a[2][2] = { 0, 1, 2, 3 };
- int b[2][2] = { { 0, 1 }, { 2, 3 } };
-
-`-Wparentheses'
- Warn if parentheses are omitted in certain contexts, such as when
- there is an assignment in a context where a truth value is
- expected, or when operators are nested whose precedence people
- often get confused about.
-
- Also warn about constructions where there may be confusion to which
- `if' statement an `else' branch belongs. Here is an example of
- such a case:
+Both the C and C++ standard have the concept of volatile objects. These
+are normally accessed by pointers and used for accessing hardware. The
+standards encourage compilers to refrain from optimizations concerning
+accesses to volatile objects that it might perform on non-volatile
+objects. The C standard leaves it implementation defined as to what
+constitutes a volatile access. The C++ standard omits to specify this,
+except to say that C++ should behave in a similar manner to C with
+respect to volatiles, where possible. The minimum either standard
+specifies is that at a sequence point all previous accesses to volatile
+objects have stabilized and no subsequent accesses have occurred. Thus
+an implementation is free to reorder and combine volatile accesses
+which occur between sequence points, but cannot do so for accesses
+across a sequence point. The use of volatiles does not allow you to
+violate the restriction on updating objects multiple times within a
+sequence point.
+
+ In most expressions, it is intuitively obvious what is a read and
+what is a write. For instance
+
+ volatile int *dst = SOMEVALUE;
+ volatile int *src = SOMEOTHERVALUE;
+ *dst = *src;
+
+will cause a read of the volatile object pointed to by SRC and stores
+the value into the volatile object pointed to by DST. There is no
+guarantee that these reads and writes are atomic, especially for objects
+larger than `int'.
+
+ Less obvious expressions are where something which looks like an
+access is used in a void context. An example would be,
+
+ volatile int *src = SOMEVALUE;
+ *src;
+
+ With C, such expressions are rvalues, and as rvalues cause a read of
+the object, GCC interprets this as a read of the volatile being pointed
+to. The C++ standard specifies that such expressions do not undergo
+lvalue to rvalue conversion, and that the type of the dereferenced
+object may be incomplete. The C++ standard does not specify explicitly
+that it is this lvalue to rvalue conversion which is responsible for
+causing an access. However, there is reason to believe that it is,
+because otherwise certain simple expressions become undefined. However,
+because it would surprise most programmers, G++ treats dereferencing a
+pointer to volatile object of complete type in a void context as a read
+of the object. When the object has incomplete type, G++ issues a
+warning.
+
+ struct S;
+ struct T {int m;};
+ volatile S *ptr1 = SOMEVALUE;
+ volatile T *ptr2 = SOMEVALUE;
+ *ptr1;
+ *ptr2;
+
+ In this example, a warning is issued for `*ptr1', and `*ptr2' causes
+a read of the object pointed to. If you wish to force an error on the
+first case, you must force a conversion to rvalue with, for instance a
+static cast, `static_cast<S>(*ptr1)'.
+
+ When using a reference to volatile, G++ does not treat equivalent
+expressions as accesses to volatiles, but instead issues a warning that
+no volatile is accessed. The rationale for this is that otherwise it
+becomes difficult to determine where volatile access occur, and not
+possible to ignore the return value from functions returning volatile
+references. Again, if you wish to force a read, cast the reference to
+an rvalue.
- {
- if (a)
- if (b)
- foo ();
- else
- bar ();
- }
+\1f
+File: gcc.info, Node: Restricted Pointers, Next: Vague Linkage, Prev: Volatiles, Up: C++ Extensions
- In C, every `else' branch belongs to the innermost possible `if'
- statement, which in this example is `if (b)'. This is often not
- what the programmer expected, as illustrated in the above example
- by indentation the programmer chose. When there is the potential
- for this confusion, GCC will issue a warning when this flag is
- specified. To eliminate the warning, add explicit braces around
- the innermost `if' statement so there is no way the `else' could
- belong to the enclosing `if'. The resulting code would look like
- this:
+6.3 Restricting Pointer Aliasing
+================================
- {
- if (a)
- {
- if (b)
- foo ();
- else
- bar ();
- }
- }
+As with gcc, g++ understands the C99 feature of restricted pointers,
+specified with the `__restrict__', or `__restrict' type qualifier.
+Because you cannot compile C++ by specifying the `-std=c99' language
+flag, `restrict' is not a keyword in C++.
+
+ In addition to allowing restricted pointers, you can specify
+restricted references, which indicate that the reference is not aliased
+in the local context.
+
+ void fn (int *__restrict__ rptr, int &__restrict__ rref)
+ {
+ ...
+ }
+
+In the body of `fn', RPTR points to an unaliased integer and RREF
+refers to a (different) unaliased integer.
+
+ You may also specify whether a member function's THIS pointer is
+unaliased by using `__restrict__' as a member function qualifier.
+
+ void T::fn () __restrict__
+ {
+ ...
+ }
+
+Within the body of `T::fn', THIS will have the effective definition `T
+*__restrict__ const this'. Notice that the interpretation of a
+`__restrict__' member function qualifier is different to that of
+`const' or `volatile' qualifier, in that it is applied to the pointer
+rather than the object. This is consistent with other compilers which
+implement restricted pointers.
+
+ As with all outermost parameter qualifiers, `__restrict__' is
+ignored in function definition matching. This means you only need to
+specify `__restrict__' in a function definition, rather than in a
+function prototype as well.
+
+\1f
+File: gcc.info, Node: Vague Linkage, Next: C++ Interface, Prev: Restricted Pointers, Up: C++ Extensions
+
+6.4 Vague Linkage
+=================
+
+There are several constructs in C++ which require space in the object
+file but are not clearly tied to a single translation unit. We say that
+these constructs have "vague linkage". Typically such constructs are
+emitted wherever they are needed, though sometimes we can be more
+clever.
+
+Inline Functions
+ Inline functions are typically defined in a header file which can
+ be included in many different compilations. Hopefully they can
+ usually be inlined, but sometimes an out-of-line copy is
+ necessary, if the address of the function is taken or if inlining
+ fails. In general, we emit an out-of-line copy in all translation
+ units where one is needed. As an exception, we only emit inline
+ virtual functions with the vtable, since it will always require a
+ copy.
+
+ Local static variables and string constants used in an inline
+ function are also considered to have vague linkage, since they
+ must be shared between all inlined and out-of-line instances of
+ the function.
+
+VTables
+ C++ virtual functions are implemented in most compilers using a
+ lookup table, known as a vtable. The vtable contains pointers to
+ the virtual functions provided by a class, and each object of the
+ class contains a pointer to its vtable (or vtables, in some
+ multiple-inheritance situations). If the class declares any
+ non-inline, non-pure virtual functions, the first one is chosen as
+ the "key method" for the class, and the vtable is only emitted in
+ the translation unit where the key method is defined.
+
+ _Note:_ If the chosen key method is later defined as inline, the
+ vtable will still be emitted in every translation unit which
+ defines it. Make sure that any inline virtuals are declared
+ inline in the class body, even if they are not defined there.
+
+type_info objects
+ C++ requires information about types to be written out in order to
+ implement `dynamic_cast', `typeid' and exception handling. For
+ polymorphic classes (classes with virtual functions), the type_info
+ object is written out along with the vtable so that `dynamic_cast'
+ can determine the dynamic type of a class object at runtime. For
+ all other types, we write out the type_info object when it is
+ used: when applying `typeid' to an expression, throwing an object,
+ or referring to a type in a catch clause or exception
+ specification.
+
+Template Instantiations
+ Most everything in this section also applies to template
+ instantiations, but there are other options as well. *Note
+ Where's the Template?: Template Instantiation.
+
+
+ When used with GNU ld version 2.8 or later on an ELF system such as
+Linux/GNU or Solaris 2, or on Microsoft Windows, duplicate copies of
+these constructs will be discarded at link time. This is known as
+COMDAT support.
+
+ On targets that don't support COMDAT, but do support weak symbols,
+GCC will use them. This way one copy will override all the others, but
+the unused copies will still take up space in the executable.
+
+ For targets which do not support either COMDAT or weak symbols, most
+entities with vague linkage will be emitted as local symbols to avoid
+duplicate definition errors from the linker. This will not happen for
+local statics in inlines, however, as having multiple copies will
+almost certainly break things.
+
+ *Note Declarations and Definitions in One Header: C++ Interface, for
+another way to control placement of these constructs.
+
+\1f
+File: gcc.info, Node: C++ Interface, Next: Template Instantiation, Prev: Vague Linkage, Up: C++ Extensions
+
+6.5 Declarations and Definitions in One Header
+==============================================
+
+C++ object definitions can be quite complex. In principle, your source
+code will need two kinds of things for each object that you use across
+more than one source file. First, you need an "interface"
+specification, describing its structure with type declarations and
+function prototypes. Second, you need the "implementation" itself. It
+can be tedious to maintain a separate interface description in a header
+file, in parallel to the actual implementation. It is also dangerous,
+since separate interface and implementation definitions may not remain
+parallel.
+
+ With GNU C++, you can use a single header file for both purposes.
+
+ _Warning:_ The mechanism to specify this is in transition. For the
+ nonce, you must use one of two `#pragma' commands; in a future
+ release of GNU C++, an alternative mechanism will make these
+ `#pragma' commands unnecessary.
+
+ The header file contains the full definitions, but is marked with
+`#pragma interface' in the source code. This allows the compiler to
+use the header file only as an interface specification when ordinary
+source files incorporate it with `#include'. In the single source file
+where the full implementation belongs, you can use either a naming
+convention or `#pragma implementation' to indicate this alternate use
+of the header file.
+
+`#pragma interface'
+`#pragma interface "SUBDIR/OBJECTS.h"'
+ Use this directive in _header files_ that define object classes,
+ to save space in most of the object files that use those classes.
+ Normally, local copies of certain information (backup copies of
+ inline member functions, debugging information, and the internal
+ tables that implement virtual functions) must be kept in each
+ object file that includes class definitions. You can use this
+ pragma to avoid such duplication. When a header file containing
+ `#pragma interface' is included in a compilation, this auxiliary
+ information will not be generated (unless the main input source
+ file itself uses `#pragma implementation'). Instead, the object
+ files will contain references to be resolved at link time.
+
+ The second form of this directive is useful for the case where you
+ have multiple headers with the same name in different directories.
+ If you use this form, you must specify the same string to `#pragma
+ implementation'.
+
+`#pragma implementation'
+`#pragma implementation "OBJECTS.h"'
+ Use this pragma in a _main input file_, when you want full output
+ from included header files to be generated (and made globally
+ visible). The included header file, in turn, should use `#pragma
+ interface'. Backup copies of inline member functions, debugging
+ information, and the internal tables used to implement virtual
+ functions are all generated in implementation files.
+
+ If you use `#pragma implementation' with no argument, it applies to
+ an include file with the same basename(1) as your source file.
+ For example, in `allclass.cc', giving just `#pragma implementation'
+ by itself is equivalent to `#pragma implementation "allclass.h"'.
+
+ In versions of GNU C++ prior to 2.6.0 `allclass.h' was treated as
+ an implementation file whenever you would include it from
+ `allclass.cc' even if you never specified `#pragma
+ implementation'. This was deemed to be more trouble than it was
+ worth, however, and disabled.
+
+ If you use an explicit `#pragma implementation', it must appear in
+ your source file _before_ you include the affected header files.
+
+ Use the string argument if you want a single implementation file to
+ include code from multiple header files. (You must also use
+ `#include' to include the header file; `#pragma implementation'
+ only specifies how to use the file--it doesn't actually include
+ it.)
+
+ There is no way to split up the contents of a single header file
+ into multiple implementation files.
+
+ `#pragma implementation' and `#pragma interface' also have an effect
+on function inlining.
+
+ If you define a class in a header file marked with `#pragma
+interface', the effect on a function defined in that class is similar to
+an explicit `extern' declaration--the compiler emits no code at all to
+define an independent version of the function. Its definition is used
+only for inlining with its callers.
+
+ Conversely, when you include the same header file in a main source
+file that declares it as `#pragma implementation', the compiler emits
+code for the function itself; this defines a version of the function
+that can be found via pointers (or by callers compiled without
+inlining). If all calls to the function can be inlined, you can avoid
+emitting the function by compiling with `-fno-implement-inlines'. If
+any calls were not inlined, you will get linker errors.
+
+ ---------- Footnotes ----------
+
+ (1) A file's "basename" was the name stripped of all leading path
+information and of trailing suffixes, such as `.h' or `.C' or `.cc'.
+
+\1f
+File: gcc.info, Node: Template Instantiation, Next: Bound member functions, Prev: C++ Interface, Up: C++ Extensions
+
+6.6 Where's the Template?
+=========================
+
+C++ templates are the first language feature to require more
+intelligence from the environment than one usually finds on a UNIX
+system. Somehow the compiler and linker have to make sure that each
+template instance occurs exactly once in the executable if it is needed,
+and not at all otherwise. There are two basic approaches to this
+problem, which I will refer to as the Borland model and the Cfront
+model.
+
+Borland model
+ Borland C++ solved the template instantiation problem by adding
+ the code equivalent of common blocks to their linker; the compiler
+ emits template instances in each translation unit that uses them,
+ and the linker collapses them together. The advantage of this
+ model is that the linker only has to consider the object files
+ themselves; there is no external complexity to worry about. This
+ disadvantage is that compilation time is increased because the
+ template code is being compiled repeatedly. Code written for this
+ model tends to include definitions of all templates in the header
+ file, since they must be seen to be instantiated.
+
+Cfront model
+ The AT&T C++ translator, Cfront, solved the template instantiation
+ problem by creating the notion of a template repository, an
+ automatically maintained place where template instances are
+ stored. A more modern version of the repository works as follows:
+ As individual object files are built, the compiler places any
+ template definitions and instantiations encountered in the
+ repository. At link time, the link wrapper adds in the objects in
+ the repository and compiles any needed instances that were not
+ previously emitted. The advantages of this model are more optimal
+ compilation speed and the ability to use the system linker; to
+ implement the Borland model a compiler vendor also needs to
+ replace the linker. The disadvantages are vastly increased
+ complexity, and thus potential for error; for some code this can be
+ just as transparent, but in practice it can been very difficult to
+ build multiple programs in one directory and one program in
+ multiple directories. Code written for this model tends to
+ separate definitions of non-inline member templates into a
+ separate file, which should be compiled separately.
+
+ When used with GNU ld version 2.8 or later on an ELF system such as
+Linux/GNU or Solaris 2, or on Microsoft Windows, g++ supports the
+Borland model. On other systems, g++ implements neither automatic
+model.
+
+ A future version of g++ will support a hybrid model whereby the
+compiler will emit any instantiations for which the template definition
+is included in the compile, and store template definitions and
+instantiation context information into the object file for the rest.
+The link wrapper will extract that information as necessary and invoke
+the compiler to produce the remaining instantiations. The linker will
+then combine duplicate instantiations.
+
+ In the mean time, you have the following options for dealing with
+template instantiations:
+
+ 1. Compile your template-using code with `-frepo'. The compiler will
+ generate files with the extension `.rpo' listing all of the
+ template instantiations used in the corresponding object files
+ which could be instantiated there; the link wrapper, `collect2',
+ will then update the `.rpo' files to tell the compiler where to
+ place those instantiations and rebuild any affected object files.
+ The link-time overhead is negligible after the first pass, as the
+ compiler will continue to place the instantiations in the same
+ files.
+
+ This is your best option for application code written for the
+ Borland model, as it will just work. Code written for the Cfront
+ model will need to be modified so that the template definitions
+ are available at one or more points of instantiation; usually this
+ is as simple as adding `#include <tmethods.cc>' to the end of each
+ template header.
+
+ For library code, if you want the library to provide all of the
+ template instantiations it needs, just try to link all of its
+ object files together; the link will fail, but cause the
+ instantiations to be generated as a side effect. Be warned,
+ however, that this may cause conflicts if multiple libraries try
+ to provide the same instantiations. For greater control, use
+ explicit instantiation as described in the next option.
+
+ 2. Compile your code with `-fno-implicit-templates' to disable the
+ implicit generation of template instances, and explicitly
+ instantiate all the ones you use. This approach requires more
+ knowledge of exactly which instances you need than do the others,
+ but it's less mysterious and allows greater control. You can
+ scatter the explicit instantiations throughout your program,
+ perhaps putting them in the translation units where the instances
+ are used or the translation units that define the templates
+ themselves; you can put all of the explicit instantiations you
+ need into one big file; or you can create small files like
+
+ #include "Foo.h"
+ #include "Foo.cc"
+
+ template class Foo<int>;
+ template ostream& operator <<
+ (ostream&, const Foo<int>&);
+
+ for each of the instances you need, and create a template
+ instantiation library from those.
+
+ If you are using Cfront-model code, you can probably get away with
+ not using `-fno-implicit-templates' when compiling files that don't
+ `#include' the member template definitions.
+
+ If you use one big file to do the instantiations, you may want to
+ compile it without `-fno-implicit-templates' so you get all of the
+ instances required by your explicit instantiations (but not by any
+ other files) without having to specify them as well.
+
+ g++ has extended the template instantiation syntax outlined in the
+ Working Paper to allow forward declaration of explicit
+ instantiations (with `extern'), instantiation of the compiler
+ support data for a template class (i.e. the vtable) without
+ instantiating any of its members (with `inline'), and
+ instantiation of only the static data members of a template class,
+ without the support data or member functions (with (`static'):
+
+ extern template int max (int, int);
+ inline template class Foo<int>;
+ static template class Foo<int>;
+
+ 3. Do nothing. Pretend g++ does implement automatic instantiation
+ management. Code written for the Borland model will work fine, but
+ each translation unit will contain instances of each of the
+ templates it uses. In a large program, this can lead to an
+ unacceptable amount of code duplication.
+
+ 4. Add `#pragma interface' to all files containing template
+ definitions. For each of these files, add `#pragma implementation
+ "FILENAME"' to the top of some `.C' file which `#include's it.
+ Then compile everything with `-fexternal-templates'. The
+ templates will then only be expanded in the translation unit which
+ implements them (i.e. has a `#pragma implementation' line for the
+ file where they live); all other files will use external
+ references. If you're lucky, everything should work properly. If
+ you get undefined symbol errors, you need to make sure that each
+ template instance which is used in the program is used in the file
+ which implements that template. If you don't have any use for a
+ particular instance in that file, you can just instantiate it
+ explicitly, using the syntax from the latest C++ working paper:
+
+ template class A<int>;
+ template ostream& operator << (ostream&, const A<int>&);
+
+ This strategy will work with code written for either model. If
+ you are using code written for the Cfront model, the file
+ containing a class template and the file containing its member
+ templates should be implemented in the same translation unit.
+
+ 5. A slight variation on this approach is to use the flag
+ `-falt-external-templates' instead. This flag causes template
+ instances to be emitted in the translation unit that implements the
+ header where they are first instantiated, rather than the one which
+ implements the file where the templates are defined. This header
+ must be the same in all translation units, or things are likely to
+ break.
+
+ *Note Declarations and Definitions in One Header: C++ Interface,
+ for more discussion of these pragmas.
+
+\1f
+File: gcc.info, Node: Bound member functions, Next: C++ Attributes, Prev: Template Instantiation, Up: C++ Extensions
+
+6.7 Extracting the function pointer from a bound pointer to member function
+===========================================================================
+
+In C++, pointer to member functions (PMFs) are implemented using a wide
+pointer of sorts to handle all the possible call mechanisms; the PMF
+needs to store information about how to adjust the `this' pointer, and
+if the function pointed to is virtual, where to find the vtable, and
+where in the vtable to look for the member function. If you are using
+PMFs in an inner loop, you should really reconsider that decision. If
+that is not an option, you can extract the pointer to the function that
+would be called for a given object/PMF pair and call it directly inside
+the inner loop, to save a bit of time.
+
+ Note that you will still be paying the penalty for the call through a
+function pointer; on most modern architectures, such a call defeats the
+branch prediction features of the CPU. This is also true of normal
+virtual function calls.
+
+ The syntax for this extension is
+
+ extern A a;
+ extern int (A::*fp)();
+ typedef int (*fptr)(A *);
+
+ fptr p = (fptr)(a.*fp);
+
+ For PMF constants (i.e. expressions of the form `&Klasse::Member'),
+no object is needed to obtain the address of the function. They can be
+converted to function pointers directly:
+
+ fptr p1 = (fptr)(&A::foo);
+
+ You must specify `-Wno-pmf-conversions' to use this extension.
+
+\1f
+File: gcc.info, Node: C++ Attributes, Next: Java Exceptions, Prev: Bound member functions, Up: C++ Extensions
+
+6.8 C++-Specific Variable, Function, and Type Attributes
+========================================================
+
+Some attributes only make sense for C++ programs.
+
+`init_priority (PRIORITY)'
+ In Standard C++, objects defined at namespace scope are guaranteed
+ to be initialized in an order in strict accordance with that of
+ their definitions _in a given translation unit_. No guarantee is
+ made for initializations across translation units. However, GNU
+ C++ allows users to control the order of initialization of objects
+ defined at namespace scope with the `init_priority' attribute by
+ specifying a relative PRIORITY, a constant integral expression
+ currently bounded between 101 and 65535 inclusive. Lower numbers
+ indicate a higher priority.
+
+ In the following example, `A' would normally be created before
+ `B', but the `init_priority' attribute has reversed that order:
+
+ Some_Class A __attribute__ ((init_priority (2000)));
+ Some_Class B __attribute__ ((init_priority (543)));
+
+ Note that the particular values of PRIORITY do not matter; only
+ their relative ordering.
+
+`java_interface'
+ This type attribute informs C++ that the class is a Java
+ interface. It may only be applied to classes declared within an
+ `extern "Java"' block. Calls to methods declared in this
+ interface will be dispatched using GCJ's interface table
+ mechanism, instead of regular virtual table dispatch.
+
+
+\1f
+File: gcc.info, Node: Java Exceptions, Next: Deprecated Features, Prev: C++ Attributes, Up: C++ Extensions
+
+6.9 Java Exceptions
+===================
+
+The Java language uses a slightly different exception handling model
+from C++. Normally, GNU C++ will automatically detect when you are
+writing C++ code that uses Java exceptions, and handle them
+appropriately. However, if C++ code only needs to execute destructors
+when Java exceptions are thrown through it, GCC will guess incorrectly.
+Sample problematic code is:
+
+ struct S { ~S(); };
+ extern void bar(); // is written in Java, and may throw exceptions
+ void foo()
+ {
+ S s;
+ bar();
+ }
+
+The usual effect of an incorrect guess is a link failure, complaining of
+a missing routine called `__gxx_personality_v0'.
+
+ You can inform the compiler that Java exceptions are to be used in a
+translation unit, irrespective of what it might think, by writing
+`#pragma GCC java_exceptions' at the head of the file. This `#pragma'
+must appear before any functions that throw or catch exceptions, or run
+destructors when exceptions are thrown through them.
+
+ You cannot mix Java and C++ exceptions in the same translation unit.
+It is believed to be safe to throw a C++ exception from one file through
+another file compiled for the Java exception model, or vice versa, but
+there may be bugs in this area.
+
+\1f
+File: gcc.info, Node: Deprecated Features, Next: Backwards Compatibility, Prev: Java Exceptions, Up: C++ Extensions
+
+6.10 Deprecated Features
+========================
+
+In the past, the GNU C++ compiler was extended to experiment with new
+features, at a time when the C++ language was still evolving. Now that
+the C++ standard is complete, some of those features are superseded by
+superior alternatives. Using the old features might cause a warning in
+some cases that the feature will be dropped in the future. In other
+cases, the feature might be gone already.
+
+ While the list below is not exhaustive, it documents some of the
+options that are now deprecated:
+
+`-fexternal-templates'
+`-falt-external-templates'
+ These are two of the many ways for g++ to implement template
+ instantiation. *Note Template Instantiation::. The C++ standard
+ clearly defines how template definitions have to be organized
+ across implementation units. g++ has an implicit instantiation
+ mechanism that should work just fine for standard-conforming code.
+
+`-fstrict-prototype'
+`-fno-strict-prototype'
+ Previously it was possible to use an empty prototype parameter
+ list to indicate an unspecified number of parameters (like C),
+ rather than no parameters, as C++ demands. This feature has been
+ removed, except where it is required for backwards compatibility
+ *Note Backwards Compatibility::.
+
+ The named return value extension has been deprecated, and is now
+removed from g++.
+
+ The use of initializer lists with new expressions has been
+deprecated, and is now removed from g++.
+
+ Floating and complex non-type template parameters have been
+deprecated, and are now removed from g++.
+
+ The implicit typename extension has been deprecated and will be
+removed from g++ at some point. In some cases g++ determines that a
+dependant type such as `TPL<T>::X' is a type without needing a
+`typename' keyword, contrary to the standard.
+
+\1f
+File: gcc.info, Node: Backwards Compatibility, Prev: Deprecated Features, Up: C++ Extensions
+
+6.11 Backwards Compatibility
+============================
+
+Now that there is a definitive ISO standard C++, G++ has a specification
+to adhere to. The C++ language evolved over time, and features that
+used to be acceptable in previous drafts of the standard, such as the
+ARM [Annotated C++ Reference Manual], are no longer accepted. In order
+to allow compilation of C++ written to such drafts, G++ contains some
+backwards compatibilities. _All such backwards compatibility features
+are liable to disappear in future versions of G++._ They should be
+considered deprecated *Note Deprecated Features::.
+
+`For scope'
+ If a variable is declared at for scope, it used to remain in scope
+ until the end of the scope which contained the for statement
+ (rather than just within the for scope). G++ retains this, but
+ issues a warning, if such a variable is accessed outside the for
+ scope.
+
+`Implicit C language'
+ Old C system header files did not contain an `extern "C" {...}'
+ scope to set the language. On such systems, all header files are
+ implicitly scoped inside a C language scope. Also, an empty
+ prototype `()' will be treated as an unspecified number of
+ arguments, rather than no arguments, as C++ demands.
+
+\1f
+File: gcc.info, Node: Objective-C, Next: Compatibility, Prev: C++ Extensions, Up: Top
+
+7 GNU Objective-C runtime features
+**********************************
+
+This document is meant to describe some of the GNU Objective-C runtime
+features. It is not intended to teach you Objective-C, there are
+several resources on the Internet that present the language. Questions
+and comments about this document to Ovidiu Predescu <ovidiu@cup.hp.com>.
+
+* Menu:
+
+* Executing code before main::
+* Type encoding::
+* Garbage Collection::
+* Constant string objects::
+* compatibility_alias::
+
+\1f
+File: gcc.info, Node: Executing code before main, Next: Type encoding, Prev: Objective-C, Up: Objective-C
+
+7.1 `+load': Executing code before main
+=======================================
+
+The GNU Objective-C runtime provides a way that allows you to execute
+code before the execution of the program enters the `main' function.
+The code is executed on a per-class and a per-category basis, through a
+special class method `+load'.
+
+ This facility is very useful if you want to initialize global
+variables which can be accessed by the program directly, without
+sending a message to the class first. The usual way to initialize
+global variables, in the `+initialize' method, might not be useful
+because `+initialize' is only called when the first message is sent to a
+class object, which in some cases could be too late.
+
+ Suppose for example you have a `FileStream' class that declares
+`Stdin', `Stdout' and `Stderr' as global variables, like below:
+
+
+ FileStream *Stdin = nil;
+ FileStream *Stdout = nil;
+ FileStream *Stderr = nil;
+
+ @implementation FileStream
+
+ + (void)initialize
+ {
+ Stdin = [[FileStream new] initWithFd:0];
+ Stdout = [[FileStream new] initWithFd:1];
+ Stderr = [[FileStream new] initWithFd:2];
+ }
+
+ /* Other methods here */
+ @end
+
+ In this example, the initialization of `Stdin', `Stdout' and
+`Stderr' in `+initialize' occurs too late. The programmer can send a
+message to one of these objects before the variables are actually
+initialized, thus sending messages to the `nil' object. The
+`+initialize' method which actually initializes the global variables is
+not invoked until the first message is sent to the class object. The
+solution would require these variables to be initialized just before
+entering `main'.
+
+ The correct solution of the above problem is to use the `+load'
+method instead of `+initialize':
+
+
+ @implementation FileStream
+
+ + (void)load
+ {
+ Stdin = [[FileStream new] initWithFd:0];
+ Stdout = [[FileStream new] initWithFd:1];
+ Stderr = [[FileStream new] initWithFd:2];
+ }
+
+ /* Other methods here */
+ @end
+
+ The `+load' is a method that is not overridden by categories. If a
+class and a category of it both implement `+load', both methods are
+invoked. This allows some additional initializations to be performed in
+a category.
+
+ This mechanism is not intended to be a replacement for `+initialize'.
+You should be aware of its limitations when you decide to use it
+instead of `+initialize'.
+
+* Menu:
+
+* What you can and what you cannot do in +load::
+
+\1f
+File: gcc.info, Node: What you can and what you cannot do in +load, Prev: Executing code before main, Up: Executing code before main
+
+7.1.1 What you can and what you cannot do in `+load'
+----------------------------------------------------
+
+The `+load' implementation in the GNU runtime guarantees you the
+following things:
+
+ * you can write whatever C code you like;
+
+ * you can send messages to Objective-C constant strings (`@"this is a
+ constant string"');
+
+ * you can allocate and send messages to objects whose class is
+ implemented in the same file;
+
+ * the `+load' implementation of all super classes of a class are
+ executed before the `+load' of that class is executed;
+
+ * the `+load' implementation of a class is executed before the
+ `+load' implementation of any category.
+
+
+ In particular, the following things, even if they can work in a
+particular case, are not guaranteed:
+
+ * allocation of or sending messages to arbitrary objects;
+
+ * allocation of or sending messages to objects whose classes have a
+ category implemented in the same file;
+
+
+ You should make no assumptions about receiving `+load' in sibling
+classes when you write `+load' of a class. The order in which sibling
+classes receive `+load' is not guaranteed.
+
+ The order in which `+load' and `+initialize' are called could be
+problematic if this matters. If you don't allocate objects inside
+`+load', it is guaranteed that `+load' is called before `+initialize'.
+If you create an object inside `+load' the `+initialize' method of
+object's class is invoked even if `+load' was not invoked. Note if you
+explicitly call `+load' on a class, `+initialize' will be called first.
+To avoid possible problems try to implement only one of these methods.
+
+ The `+load' method is also invoked when a bundle is dynamically
+loaded into your running program. This happens automatically without
+any intervening operation from you. When you write bundles and you
+need to write `+load' you can safely create and send messages to
+objects whose classes already exist in the running program. The same
+restrictions as above apply to classes defined in bundle.
+
+\1f
+File: gcc.info, Node: Type encoding, Next: Garbage Collection, Prev: Executing code before main, Up: Objective-C
+
+7.2 Type encoding
+=================
+
+The Objective-C compiler generates type encodings for all the types.
+These type encodings are used at runtime to find out information about
+selectors and methods and about objects and classes.
+
+ The types are encoded in the following way:
+
+`char' `c'
+`unsigned char' `C'
+`short' `s'
+`unsigned short' `S'
+`int' `i'
+`unsigned int' `I'
+`long' `l'
+`unsigned long' `L'
+`long long' `q'
+`unsigned long `Q'
+long'
+`float' `f'
+`double' `d'
+`void' `v'
+`id' `@'
+`Class' `#'
+`SEL' `:'
+`char*' `*'
+unknown type `?'
+bit-fields `b' followed by the starting position of the
+ bit-field, the type of the bit-field and the size of
+ the bit-field (the bit-fields encoding was changed
+ from the NeXT's compiler encoding, see below)
+
+ The encoding of bit-fields has changed to allow bit-fields to be
+properly handled by the runtime functions that compute sizes and
+alignments of types that contain bit-fields. The previous encoding
+contained only the size of the bit-field. Using only this information
+it is not possible to reliably compute the size occupied by the
+bit-field. This is very important in the presence of the Boehm's
+garbage collector because the objects are allocated using the typed
+memory facility available in this collector. The typed memory
+allocation requires information about where the pointers are located
+inside the object.
+
+ The position in the bit-field is the position, counting in bits, of
+the bit closest to the beginning of the structure.
+
+ The non-atomic types are encoded as follows:
+
+pointers `^' followed by the pointed type.
+arrays `[' followed by the number of elements in the array
+ followed by the type of the elements followed by `]'
+structures `{' followed by the name of the structure (or `?' if the
+ structure is unnamed), the `=' sign, the type of the
+ members and by `}'
+unions `(' followed by the name of the structure (or `?' if the
+ union is unnamed), the `=' sign, the type of the members
+ followed by `)'
+
+ Here are some types and their encodings, as they are generated by the
+compiler on an i386 machine:
+
+
+Objective-C type Compiler encoding
+ int a[10]; `[10i]'
+ struct { `{?=i[3f]b128i3b131i2c}'
+ int i;
+ float f[3];
+ int a:3;
+ int b:2;
+ char c;
+ }
+
+
+ In addition to the types the compiler also encodes the type
+specifiers. The table below describes the encoding of the current
+Objective-C type specifiers:
+
+
+Specifier Encoding
+`const' `r'
+`in' `n'
+`inout' `N'
+`out' `o'
+`bycopy' `O'
+`oneway' `V'
+
+
+ The type specifiers are encoded just before the type. Unlike types
+however, the type specifiers are only encoded when they appear in method
+argument types.
+
+\1f
+File: gcc.info, Node: Garbage Collection, Next: Constant string objects, Prev: Type encoding, Up: Objective-C
+
+7.3 Garbage Collection
+======================
+
+Support for a new memory management policy has been added by using a
+powerful conservative garbage collector, known as the
+Boehm-Demers-Weiser conservative garbage collector. It is available
+from `http://www.hpl.hp.com/personal/Hans_Boehm/gc/'.
+
+ To enable the support for it you have to configure the compiler
+using an additional argument, `--enable-objc-gc'. You need to have
+garbage collector installed before building the compiler. This will
+build an additional runtime library which has several enhancements to
+support the garbage collector. The new library has a new name,
+`libobjc_gc.a' to not conflict with the non-garbage-collected library.
+
+ When the garbage collector is used, the objects are allocated using
+the so-called typed memory allocation mechanism available in the
+Boehm-Demers-Weiser collector. This mode requires precise information
+on where pointers are located inside objects. This information is
+computed once per class, immediately after the class has been
+initialized.
+
+ There is a new runtime function `class_ivar_set_gcinvisible()' which
+can be used to declare a so-called "weak pointer" reference. Such a
+pointer is basically hidden for the garbage collector; this can be
+useful in certain situations, especially when you want to keep track of
+the allocated objects, yet allow them to be collected. This kind of
+pointers can only be members of objects, you cannot declare a global
+pointer as a weak reference. Every type which is a pointer type can be
+declared a weak pointer, including `id', `Class' and `SEL'.
+
+ Here is an example of how to use this feature. Suppose you want to
+implement a class whose instances hold a weak pointer reference; the
+following class does this:
+
+
+ @interface WeakPointer : Object
+ {
+ const void* weakPointer;
+ }
+
+ - initWithPointer:(const void*)p;
+ - (const void*)weakPointer;
+ @end
+
+
+ @implementation WeakPointer
+
+ + (void)initialize
+ {
+ class_ivar_set_gcinvisible (self, "weakPointer", YES);
+ }
+
+ - initWithPointer:(const void*)p
+ {
+ weakPointer = p;
+ return self;
+ }
+
+ - (const void*)weakPointer
+ {
+ return weakPointer;
+ }
+
+ @end
+
+ Weak pointers are supported through a new type character specifier
+represented by the `!' character. The `class_ivar_set_gcinvisible()'
+function adds or removes this specifier to the string type description
+of the instance variable named as argument.
+
+\1f
+File: gcc.info, Node: Constant string objects, Next: compatibility_alias, Prev: Garbage Collection, Up: Objective-C
+
+7.4 Constant string objects
+===========================
+
+GNU Objective-C provides constant string objects that are generated
+directly by the compiler. You declare a constant string object by
+prefixing a C constant string with the character `@':
+
+ id myString = @"this is a constant string object";
+
+ The constant string objects are usually instances of the
+`NXConstantString' class which is provided by the GNU Objective-C
+runtime. To get the definition of this class you must include the
+`objc/NXConstStr.h' header file.
-`-Wsequence-point'
- Warn about code that may have undefined semantics because of
- violations of sequence point rules in the C standard.
-
- The C standard defines the order in which expressions in a C
- program are evaluated in terms of "sequence points", which
- represent a partial ordering between the execution of parts of the
- program: those executed before the sequence point, and those
- executed after it. These occur after the evaluation of a full
- expression (one which is not part of a larger expression), after
- the evaluation of the first operand of a `&&', `||', `? :' or `,'
- (comma) operator, before a function is called (but after the
- evaluation of its arguments and the expression denoting the called
- function), and in certain other places. Other than as expressed
- by the sequence point rules, the order of evaluation of
- subexpressions of an expression is not specified. All these rules
- describe only a partial order rather than a total order, since,
- for example, if two functions are called within one expression
- with no sequence point between them, the order in which the
- functions are called is not specified. However, the standards
- committee have ruled that function calls do not overlap.
-
- It is not specified when between sequence points modifications to
- the values of objects take effect. Programs whose behavior
- depends on this have undefined behavior; the C standard specifies
- that "Between the previous and next sequence point an object shall
- have its stored value modified at most once by the evaluation of
- an expression. Furthermore, the prior value shall be read only to
- determine the value to be stored.". If a program breaks these
- rules, the results on any particular implementation are entirely
- unpredictable.
-
- Examples of code with undefined behavior are `a = a++;', `a[n] =
- b[n++]' and `a[i++] = i;'. Some more complicated cases are not
- diagnosed by this option, and it may give an occasional false
- positive result, but in general it has been found fairly effective
- at detecting this sort of problem in programs.
-
- The present implementation of this option only works for C
- programs. A future implementation may also work for C++ programs.
-
- The C standard is worded confusingly, therefore there is some
- debate over the precise meaning of the sequence point rules in
- subtle cases. Links to discussions of the problem, including
- proposed formal definitions, may be found on our readings page, at
- `http://gcc.gnu.org/readings.html'.
-
-`-Wreturn-type'
- Warn whenever a function is defined with a return-type that
- defaults to `int'. Also warn about any `return' statement with no
- return-value in a function whose return-type is not `void'.
-
- For C++, a function without return type always produces a
- diagnostic message, even when `-Wno-return-type' is specified.
- The only exceptions are `main' and functions defined in system
- headers.
-
-`-Wswitch'
- Warn whenever a `switch' statement has an index of enumeral type
- and lacks a `case' for one or more of the named codes of that
- enumeration. (The presence of a `default' label prevents this
- warning.) `case' labels outside the enumeration range also
- provoke warnings when this option is used.
-
-`-Wtrigraphs'
- Warn if any trigraphs are encountered that might change the
- meaning of the program (trigraphs within comments are not warned
- about).
-
-`-Wunused-function'
- Warn whenever a static function is declared but not defined or a
- non\-inline static function is unused.
-
-`-Wunused-label'
- Warn whenever a label is declared but not used.
-
- To suppress this warning use the `unused' attribute (*note
- Variable Attributes::).
-
-`-Wunused-parameter'
- Warn whenever a function parameter is unused aside from its
- declaration.
-
- To suppress this warning use the `unused' attribute (*note
- Variable Attributes::).
-
-`-Wunused-variable'
- Warn whenever a local variable or non-constant static variable is
- unused aside from its declaration
-
- To suppress this warning use the `unused' attribute (*note
- Variable Attributes::).
-
-`-Wunused-value'
- Warn whenever a statement computes a result that is explicitly not
- used.
-
- To suppress this warning cast the expression to `void'.
-
-`-Wunused'
- All all the above `-Wunused' options combined.
-
- In order to get a warning about an unused function parameter, you
- must either specify `-W -Wunused' or separately specify
- `-Wunused-parameter'.
-
-`-Wuninitialized'
- Warn if an automatic variable is used without first being
- initialized or if a variable may be clobbered by a `setjmp' call.
-
- These warnings are possible only in optimizing compilation,
- because they require data flow information that is computed only
- when optimizing. If you don't specify `-O', you simply won't get
- these warnings.
-
- These warnings occur only for variables that are candidates for
- register allocation. Therefore, they do not occur for a variable
- that is declared `volatile', or whose address is taken, or whose
- size is other than 1, 2, 4 or 8 bytes. Also, they do not occur for
- structures, unions or arrays, even when they are in registers.
-
- Note that there may be no warning about a variable that is used
- only to compute a value that itself is never used, because such
- computations may be deleted by data flow analysis before the
- warnings are printed.
-
- These warnings are made optional because GCC is not smart enough
- to see all the reasons why the code might be correct despite
- appearing to have an error. Here is one example of how this can
- happen:
+ User defined libraries may want to implement their own constant
+string class. To be able to support them, the GNU Objective-C compiler
+provides a new command line options
+`-fconstant-string-class=CLASS-NAME'. The provided class should adhere
+to a strict structure, the same as `NXConstantString''s structure:
+
+ @interface NXConstantString : Object
+ {
+ char *c_string;
+ unsigned int len;
+ }
+ @end
+
+ User class libraries may choose to inherit the customized constant
+string class from a different class than `Object'. There is no
+requirement in the methods the constant string class has to implement.
+
+ When a file is compiled with the `-fconstant-string-class' option,
+all the constant string objects will be instances of the class specified
+as argument to this option. It is possible to have multiple compilation
+units referring to different constant string classes, neither the
+compiler nor the linker impose any restrictions in doing this.
+
+\1f
+File: gcc.info, Node: compatibility_alias, Prev: Constant string objects, Up: Objective-C
+
+7.5 compatibility_alias
+=======================
+
+This is a feature of the Objective-C compiler rather than of the
+runtime, anyway since it is documented nowhere and its existence was
+forgotten, we are documenting it here.
+
+ The keyword `@compatibility_alias' allows you to define a class name
+as equivalent to another class name. For example:
+
+ @compatibility_alias WOApplication GSWApplication;
+
+ tells the compiler that each time it encounters `WOApplication' as a
+class name, it should replace it with `GSWApplication' (that is,
+`WOApplication' is just an alias for `GSWApplication').
+
+ There are some constraints on how this can be used--
+
+ * `WOApplication' (the alias) must not be an existing class;
+
+ * `GSWApplication' (the real class) must be an existing class.
+
+
+\1f
+File: gcc.info, Node: Compatibility, Next: Gcov, Prev: Objective-C, Up: Top
+
+8 Binary Compatibility
+**********************
+
+Binary compatibility encompasses several related concepts:
+
+"application binary interface (ABI)"
+ The set of runtime conventions followed by all of the tools that
+ deal with binary representations of a program, including
+ compilers, assemblers, linkers, and language runtime support.
+ Some ABIs are formal with a written specification, possibly
+ designed by multiple interested parties. Others are simply the
+ way things are actually done by a particular set of tools.
+
+"ABI conformance"
+ A compiler conforms to an ABI if it generates code that follows
+ all of the specifications enumerated by that ABI. A library
+ conforms to an ABI if it is implemented according to that ABI. An
+ application conforms to an ABI if it is built using tools that
+ conform to that ABI and does not contain source code that
+ specifically changes behavior specified by the ABI.
+
+"calling conventions"
+ Calling conventions are a subset of an ABI that specify of how
+ arguments are passed and function results are returned.
+
+"interoperability"
+ Different sets of tools are interoperable if they generate files
+ that can be used in the same program. The set of tools includes
+ compilers, assemblers, linkers, libraries, header files, startup
+ files, and debuggers. Binaries produced by different sets of
+ tools are not interoperable unless they implement the same ABI.
+ This applies to different versions of the same tools as well as
+ tools from different vendors.
+
+"intercallability"
+ Whether a function in a binary built by one set of tools can call a
+ function in a binary built by a different set of tools is a subset
+ of interoperability.
+
+"implementation-defined features"
+ Language standards include lists of implementation-defined
+ features whose behavior can vary from one implementation to
+ another. Some of these features are normally covered by a
+ platform's ABI and others are not. The features that are not
+ covered by an ABI generally affect how a program behaves, but not
+ intercallability.
+
+"compatibility"
+ Conformance to the same ABI and the same behavior of
+ implementation-defined features are both relevant for
+ compatibility.
+
+ The application binary interface implemented by a C or C++ compiler
+affects code generation and runtime support for:
+
+ * size and alignment of data types
+
+ * layout of structured types
+
+ * calling conventions
+
+ * register usage conventions
+
+ * interfaces for runtime arithmetic support
+
+ * object file formats
+
+ In addition, the application binary interface implemented by a C++
+compiler affects code generation and runtime support for:
+ * name mangling
+
+ * exception handling
+
+ * invoking constructors and destructors
+
+ * layout, alignment, and padding of classes
+
+ * layout and alignment of virtual tables
+
+ Some GCC compilation options cause the compiler to generate code that
+does not conform to the platform's default ABI. Other options cause
+different program behavior for implementation-defined features that are
+not covered by an ABI. These options are provided for consistency with
+other compilers that do not follow the platform's default ABI or the
+usual behavior of implementation-defined features for the platform. Be
+very careful about using such options.
+
+ Most platforms have a well-defined ABI that covers C code, but ABIs
+that cover C++ functionality are not yet common.
+
+ Starting with GCC 3.2, GCC binary conventions for C++ are based on a
+written, vendor-neutral C++ ABI that was designed to be specific to
+64-bit Itanium but also includes generic specifications that apply to
+any platform. This C++ ABI is also implemented by other compiler
+vendors on some platforms, notably GNU/Linux and BSD systems. We have
+tried hard to provide a stable ABI that will be compatible with future
+GCC releases, but it is possible that we will encounter problems that
+make this difficult. Such problems could include different
+interpretations of the C++ ABI by different vendors, bugs in the ABI, or
+bugs in the implementation of the ABI in different compilers. GCC's
+`-Wabi' switch warns when G++ generates code that is probably not
+compatible with the C++ ABI.
+
+ The C++ library used with a C++ compiler includes the Standard C++
+Library, with functionality defined in the C++ Standard, plus language
+runtime support. The runtime support is included in a C++ ABI, but
+there is no formal ABI for the Standard C++ Library. Two
+implementations of that library are interoperable if one follows the
+de-facto ABI of the other and if they are both built with the same
+compiler, or with compilers that conform to the same ABI for C++
+compiler and runtime support.
+
+ When G++ and another C++ compiler conform to the same C++ ABI, but
+the implementations of the Standard C++ Library that they normally use
+do not follow the same ABI for the Standard C++ Library, object files
+built with those compilers can be used in the same program only if they
+use the same C++ library. This requires specifying the location of the
+C++ library header files when invoking the compiler whose usual library
+is not being used. The location of GCC's C++ header files depends on
+how the GCC build was configured, but can be seen by using the G++ `-v'
+option. With default configuration options for G++ 3.2 the compile
+line for a different C++ compiler needs to include
+
+ -IGCC_INSTALL_DIRECTORY/include/c++/3.2
+
+ Similarly, compiling code with G++ that must use a C++ library other
+than the GNU C++ library requires specifying the location of the header
+files for that other library.
+
+ The most straightforward way to link a program to use a particular
+C++ library is to use a C++ driver that specifies that C++ library by
+default. The `g++' driver, for example, tells the linker where to find
+GCC's C++ library (`libstdc++') plus the other libraries and startup
+files it needs, in the proper order.
+
+ If a program must use a different C++ library and it's not possible
+to do the final link using a C++ driver that uses that library by
+default, it is necessary to tell `g++' the location and name of that
+library. It might also be necessary to specify different startup files
+and other runtime support libraries, and to suppress the use of GCC's
+support libraries with one or more of the options `-nostdlib',
+`-nostartfiles', and `-nodefaultlibs'.
+
+\1f
+File: gcc.info, Node: Gcov, Next: Trouble, Prev: Compatibility, Up: Top
+
+9 `gcov'--a Test Coverage Program
+*********************************
+
+`gcov' is a tool you can use in conjunction with GCC to test code
+coverage in your programs.
+
+* Menu:
+
+* Gcov Intro:: Introduction to gcov.
+* Invoking Gcov:: How to use gcov.
+* Gcov and Optimization:: Using gcov with GCC optimization.
+* Gcov Data Files:: The files used by gcov.
+
+\1f
+File: gcc.info, Node: Gcov Intro, Next: Invoking Gcov, Up: Gcov
+
+9.1 Introduction to `gcov'
+==========================
+
+`gcov' is a test coverage program. Use it in concert with GCC to
+analyze your programs to help create more efficient, faster running
+code. You can use `gcov' as a profiling tool to help discover where
+your optimization efforts will best affect your code. You can also use
+`gcov' along with the other profiling tool, `gprof', to assess which
+parts of your code use the greatest amount of computing time.
+
+ Profiling tools help you analyze your code's performance. Using a
+profiler such as `gcov' or `gprof', you can find out some basic
+performance statistics, such as:
+
+ * how often each line of code executes
+
+ * what lines of code are actually executed
+
+ * how much computing time each section of code uses
+
+ Once you know these things about how your code works when compiled,
+you can look at each module to see which modules should be optimized.
+`gcov' helps you determine where to work on optimization.
+
+ Software developers also use coverage testing in concert with
+testsuites, to make sure software is actually good enough for a release.
+Testsuites can verify that a program works as expected; a coverage
+program tests to see how much of the program is exercised by the
+testsuite. Developers can then determine what kinds of test cases need
+to be added to the testsuites to create both better testing and a better
+final product.
+
+ You should compile your code without optimization if you plan to use
+`gcov' because the optimization, by combining some lines of code into
+one function, may not give you as much information as you need to look
+for `hot spots' where the code is using a great deal of computer time.
+Likewise, because `gcov' accumulates statistics by line (at the lowest
+resolution), it works best with a programming style that places only
+one statement on each line. If you use complicated macros that expand
+to loops or to other control structures, the statistics are less
+helpful--they only report on the line where the macro call appears. If
+your complex macros behave like functions, you can replace them with
+inline functions to solve this problem.
+
+ `gcov' creates a logfile called `SOURCEFILE.gcov' which indicates
+how many times each line of a source file `SOURCEFILE.c' has executed.
+You can use these logfiles along with `gprof' to aid in fine-tuning the
+performance of your programs. `gprof' gives timing information you can
+use along with the information you get from `gcov'.
+
+ `gcov' works only on code compiled with GCC. It is not compatible
+with any other profiling or test coverage mechanism.
+
+\1f
+File: gcc.info, Node: Invoking Gcov, Next: Gcov and Optimization, Prev: Gcov Intro, Up: Gcov
+
+9.2 Invoking gcov
+=================
+
+ gcov [OPTIONS] SOURCEFILE
+
+ `gcov' accepts the following options:
+
+`-h'
+`--help'
+ Display help about using `gcov' (on the standard output), and exit
+ without doing any further processing.
+
+`-v'
+`--version'
+ Display the `gcov' version number (on the standard output), and
+ exit without doing any further processing.
+
+`-b'
+`--branch-probabilities'
+ Write branch frequencies to the output file, and write branch
+ summary info to the standard output. This option allows you to
+ see how often each branch in your program was taken.
+
+`-c'
+`--branch-counts'
+ Write branch frequencies as the number of branches taken, rather
+ than the percentage of branches taken.
+
+`-n'
+`--no-output'
+ Do not create the `gcov' output file.
+
+`-l'
+`--long-file-names'
+ Create long file names for included source files. For example, if
+ the header file `x.h' contains code, and was included in the file
+ `a.c', then running `gcov' on the file `a.c' will produce an
+ output file called `a.c.x.h.gcov' instead of `x.h.gcov'. This can
+ be useful if `x.h' is included in multiple source files.
+
+`-f'
+`--function-summaries'
+ Output summaries for each function in addition to the file level
+ summary.
+
+`-o DIRECTORY'
+`--object-directory DIRECTORY'
+ The directory where the object files live. Gcov will search for
+ `.bb', `.bbg', and `.da' files in this directory.
+
+ When using `gcov', you must first compile your program with two
+special GCC options: `-fprofile-arcs -ftest-coverage'. This tells the
+compiler to generate additional information needed by gcov (basically a
+flow graph of the program) and also includes additional code in the
+object files for generating the extra profiling information needed by
+gcov. These additional files are placed in the directory where the
+source code is located.
+
+ Running the program will cause profile output to be generated. For
+each source file compiled with `-fprofile-arcs', an accompanying `.da'
+file will be placed in the source directory.
+
+ Running `gcov' with your program's source file names as arguments
+will now produce a listing of the code along with frequency of execution
+for each line. For example, if your program is called `tmp.c', this is
+what you see when you use the basic `gcov' facility:
+
+ $ gcc -fprofile-arcs -ftest-coverage tmp.c
+ $ a.out
+ $ gcov tmp.c
+ 87.50% of 8 source lines executed in file tmp.c
+ Creating tmp.c.gcov.
+
+ The file `tmp.c.gcov' contains output from `gcov'. Here is a sample:
+
+ main()
+ {
+ 1 int i, total;
+
+ 1 total = 0;
+
+ 11 for (i = 0; i < 10; i++)
+ 10 total += i;
+
+ 1 if (total != 45)
+ ###### printf ("Failure\n");
+ else
+ 1 printf ("Success\n");
+ 1 }
+
+ When you use the `-b' option, your output looks like this:
+
+ $ gcov -b tmp.c
+ 87.50% of 8 source lines executed in file tmp.c
+ 80.00% of 5 branches executed in file tmp.c
+ 80.00% of 5 branches taken at least once in file tmp.c
+ 50.00% of 2 calls executed in file tmp.c
+ Creating tmp.c.gcov.
+
+ Here is a sample of a resulting `tmp.c.gcov' file:
+
+ main()
+ {
+ 1 int i, total;
+
+ 1 total = 0;
+
+ 11 for (i = 0; i < 10; i++)
+ branch 0 taken = 91%
+ branch 1 taken = 100%
+ branch 2 taken = 100%
+ 10 total += i;
+
+ 1 if (total != 45)
+ branch 0 taken = 100%
+ ###### printf ("Failure\n");
+ call 0 never executed
+ branch 1 never executed
+ else
+ 1 printf ("Success\n");
+ call 0 returns = 100%
+ 1 }
+
+ For each basic block, a line is printed after the last line of the
+basic block describing the branch or call that ends the basic block.
+There can be multiple branches and calls listed for a single source
+line if there are multiple basic blocks that end on that line. In this
+case, the branches and calls are each given a number. There is no
+simple way to map these branches and calls back to source constructs.
+In general, though, the lowest numbered branch or call will correspond
+to the leftmost construct on the source line.
+
+ For a branch, if it was executed at least once, then a percentage
+indicating the number of times the branch was taken divided by the
+number of times the branch was executed will be printed. Otherwise, the
+message "never executed" is printed.
+
+ For a call, if it was executed at least once, then a percentage
+indicating the number of times the call returned divided by the number
+of times the call was executed will be printed. This will usually be
+100%, but may be less for functions call `exit' or `longjmp', and thus
+may not return every time they are called.
+
+ The execution counts are cumulative. If the example program were
+executed again without removing the `.da' file, the count for the
+number of times each line in the source was executed would be added to
+the results of the previous run(s). This is potentially useful in
+several ways. For example, it could be used to accumulate data over a
+number of program runs as part of a test verification suite, or to
+provide more accurate long-term information over a large number of
+program runs.
+
+ The data in the `.da' files is saved immediately before the program
+exits. For each source file compiled with `-fprofile-arcs', the
+profiling code first attempts to read in an existing `.da' file; if the
+file doesn't match the executable (differing number of basic block
+counts) it will ignore the contents of the file. It then adds in the
+new execution counts and finally writes the data to the file.
+
+\1f
+File: gcc.info, Node: Gcov and Optimization, Next: Gcov Data Files, Prev: Invoking Gcov, Up: Gcov
+
+9.3 Using `gcov' with GCC Optimization
+======================================
+
+If you plan to use `gcov' to help optimize your code, you must first
+compile your program with two special GCC options: `-fprofile-arcs
+-ftest-coverage'. Aside from that, you can use any other GCC options;
+but if you want to prove that every single line in your program was
+executed, you should not compile with optimization at the same time.
+On some machines the optimizer can eliminate some simple code lines by
+combining them with other lines. For example, code like this:
+
+ if (a != b)
+ c = 1;
+ else
+ c = 0;
+
+can be compiled into one instruction on some machines. In this case,
+there is no way for `gcov' to calculate separate execution counts for
+each line because there isn't separate code for each line. Hence the
+`gcov' output looks like this if you compiled the program with
+optimization:
+
+ 100 if (a != b)
+ 100 c = 1;
+ 100 else
+ 100 c = 0;
+
+ The output shows that this block of code, combined by optimization,
+executed 100 times. In one sense this result is correct, because there
+was only one instruction representing all four of these lines. However,
+the output does not indicate how many times the result was 0 and how
+many times the result was 1.
+
+\1f
+File: gcc.info, Node: Gcov Data Files, Prev: Gcov and Optimization, Up: Gcov
+
+9.4 Brief description of `gcov' data files
+==========================================
+
+`gcov' uses three files for doing profiling. The names of these files
+are derived from the original _source_ file by substituting the file
+suffix with either `.bb', `.bbg', or `.da'. All of these files are
+placed in the same directory as the source file, and contain data
+stored in a platform-independent method.
+
+ The `.bb' and `.bbg' files are generated when the source file is
+compiled with the GCC `-ftest-coverage' option. The `.bb' file
+contains a list of source files (including headers), functions within
+those files, and line numbers corresponding to each basic block in the
+source file.
+
+ The `.bb' file format consists of several lists of 4-byte integers
+which correspond to the line numbers of each basic block in the file.
+Each list is terminated by a line number of 0. A line number of -1 is
+used to designate that the source file name (padded to a 4-byte
+boundary and followed by another -1) follows. In addition, a line
+number of -2 is used to designate that the name of a function (also
+padded to a 4-byte boundary and followed by a -2) follows.
+
+ The `.bbg' file is used to reconstruct the program flow graph for
+the source file. It contains a list of the program flow arcs (possible
+branches taken from one basic block to another) for each function which,
+in combination with the `.bb' file, enables gcov to reconstruct the
+program flow.
+
+ In the `.bbg' file, the format is:
+ number of basic blocks for function #0 (4-byte number)
+ total number of arcs for function #0 (4-byte number)
+ count of arcs in basic block #0 (4-byte number)
+ destination basic block of arc #0 (4-byte number)
+ flag bits (4-byte number)
+ destination basic block of arc #1 (4-byte number)
+ flag bits (4-byte number)
+ ...
+ destination basic block of arc #N (4-byte number)
+ flag bits (4-byte number)
+ count of arcs in basic block #1 (4-byte number)
+ destination basic block of arc #0 (4-byte number)
+ flag bits (4-byte number)
+ ...
+
+ A -1 (stored as a 4-byte number) is used to separate each function's
+list of basic blocks, and to verify that the file has been read
+correctly.
+
+ The `.da' file is generated when a program containing object files
+built with the GCC `-fprofile-arcs' option is executed. A separate
+`.da' file is created for each source file compiled with this option,
+and the name of the `.da' file is stored as an absolute pathname in the
+resulting object file. This path name is derived from the source file
+name by substituting a `.da' suffix.
+
+ The format of the `.da' file is fairly simple. The first 8-byte
+number is the number of counts in the file, followed by the counts
+(stored as 8-byte numbers). Each count corresponds to the number of
+times each arc in the program is executed. The counts are cumulative;
+each time the program is executed, it attempts to combine the existing
+`.da' files with the new counts for this invocation of the program. It
+ignores the contents of any `.da' files whose number of arcs doesn't
+correspond to the current program, and merely overwrites them instead.
+
+ All three of these files use the functions in `gcov-io.h' to store
+integers; the functions in this header provide a machine-independent
+mechanism for storing and retrieving data from a stream.
+
+\1f
+File: gcc.info, Node: Trouble, Next: Bugs, Prev: Gcov, Up: Top
+
+10 Known Causes of Trouble with GCC
+***********************************
+
+This section describes known problems that affect users of GCC. Most
+of these are not GCC bugs per se--if they were, we would fix them. But
+the result for a user may be like the result of a bug.
+
+ Some of these problems are due to bugs in other software, some are
+missing features that are too much work to add, and some are places
+where people's opinions differ as to what is best.
+
+* Menu:
+
+* Actual Bugs:: Bugs we will fix later.
+* Cross-Compiler Problems:: Common problems of cross compiling with GCC.
+* Interoperation:: Problems using GCC with other compilers,
+ and with certain linkers, assemblers and debuggers.
+* External Bugs:: Problems compiling certain programs.
+* Incompatibilities:: GCC is incompatible with traditional C.
+* Fixed Headers:: GCC uses corrected versions of system header files.
+ This is necessary, but doesn't always work smoothly.
+* Standard Libraries:: GCC uses the system C library, which might not be
+ compliant with the ISO C standard.
+* Disappointments:: Regrettable things we can't change, but not quite bugs.
+* C++ Misunderstandings:: Common misunderstandings with GNU C++.
+* Protoize Caveats:: Things to watch out for when using `protoize'.
+* Non-bugs:: Things we think are right, but some others disagree.
+* Warnings and Errors:: Which problems in your code get warnings,
+ and which get errors.
+
+\1f
+File: gcc.info, Node: Actual Bugs, Next: Cross-Compiler Problems, Up: Trouble
+
+10.1 Actual Bugs We Haven't Fixed Yet
+=====================================
+
+ * The `fixincludes' script interacts badly with automounters; if the
+ directory of system header files is automounted, it tends to be
+ unmounted while `fixincludes' is running. This would seem to be a
+ bug in the automounter. We don't know any good way to work around
+ it.
+
+ * The `fixproto' script will sometimes add prototypes for the
+ `sigsetjmp' and `siglongjmp' functions that reference the
+ `jmp_buf' type before that type is defined. To work around this,
+ edit the offending file and place the typedef in front of the
+ prototypes.
+
+ * When `-pedantic-errors' is specified, GCC will incorrectly give an
+ error message when a function name is specified in an expression
+ involving the comma operator.
+
+\1f
+File: gcc.info, Node: Cross-Compiler Problems, Next: Interoperation, Prev: Actual Bugs, Up: Trouble
+
+10.2 Cross-Compiler Problems
+============================
+
+You may run into problems with cross compilation on certain machines,
+for several reasons.
+
+ * Cross compilation can run into trouble for certain machines because
+ some target machines' assemblers require floating point numbers to
+ be written as _integer_ constants in certain contexts.
+
+ The compiler writes these integer constants by examining the
+ floating point value as an integer and printing that integer,
+ because this is simple to write and independent of the details of
+ the floating point representation. But this does not work if the
+ compiler is running on a different machine with an incompatible
+ floating point format, or even a different byte-ordering.
+
+ In addition, correct constant folding of floating point values
+ requires representing them in the target machine's format. (The C
+ standard does not quite require this, but in practice it is the
+ only way to win.)
+
+ It is now possible to overcome these problems by defining macros
+ such as `REAL_VALUE_TYPE'. But doing so is a substantial amount of
+ work for each target machine. *Note Cross Compilation and
+ Floating Point: (gccint)Cross-compilation.
+
+ * At present, the program `mips-tfile' which adds debug support to
+ object files on MIPS systems does not work in a cross compile
+ environment.
+
+\1f
+File: gcc.info, Node: Interoperation, Next: External Bugs, Prev: Cross-Compiler Problems, Up: Trouble
+
+10.3 Interoperation
+===================
+
+This section lists various difficulties encountered in using GCC
+together with other compilers or with the assemblers, linkers,
+libraries and debuggers on certain systems.
+
+ * On many platforms, GCC supports a different ABI for C++ than do
+ other compilers, so the object files compiled by GCC cannot be
+ used with object files generated by another C++ compiler.
+
+ An area where the difference is most apparent is name mangling.
+ The use of different name mangling is intentional, to protect you
+ from more subtle problems. Compilers differ as to many internal
+ details of C++ implementation, including: how class instances are
+ laid out, how multiple inheritance is implemented, and how virtual
+ function calls are handled. If the name encoding were made the
+ same, your programs would link against libraries provided from
+ other compilers--but the programs would then crash when run.
+ Incompatible libraries are then detected at link time, rather than
+ at run time.
+
+ * Older GDB versions sometimes fail to read the output of GCC version
+ 2. If you have trouble, get GDB version 4.4 or later.
+
+ * DBX rejects some files produced by GCC, though it accepts similar
+ constructs in output from PCC. Until someone can supply a coherent
+ description of what is valid DBX input and what is not, there is
+ nothing I can do about these problems. You are on your own.
+
+ * The GNU assembler (GAS) does not support PIC. To generate PIC
+ code, you must use some other assembler, such as `/bin/as'.
+
+ * On some BSD systems, including some versions of Ultrix, use of
+ profiling causes static variable destructors (currently used only
+ in C++) not to be run.
+
+ * On some SGI systems, when you use `-lgl_s' as an option, it gets
+ translated magically to `-lgl_s -lX11_s -lc_s'. Naturally, this
+ does not happen when you use GCC. You must specify all three
+ options explicitly.
+
+ * On a Sparc, GCC aligns all values of type `double' on an 8-byte
+ boundary, and it expects every `double' to be so aligned. The Sun
+ compiler usually gives `double' values 8-byte alignment, with one
+ exception: function arguments of type `double' may not be aligned.
+
+ As a result, if a function compiled with Sun CC takes the address
+ of an argument of type `double' and passes this pointer of type
+ `double *' to a function compiled with GCC, dereferencing the
+ pointer may cause a fatal signal.
+
+ One way to solve this problem is to compile your entire program
+ with GCC. Another solution is to modify the function that is
+ compiled with Sun CC to copy the argument into a local variable;
+ local variables are always properly aligned. A third solution is
+ to modify the function that uses the pointer to dereference it via
+ the following function `access_double' instead of directly with
+ `*':
+
+ inline double
+ access_double (double *unaligned_ptr)
{
- int x;
- switch (y)
- {
- case 1: x = 1;
- break;
- case 2: x = 4;
- break;
- case 3: x = 5;
- }
- foo (x);
+ union d2i { double d; int i[2]; };
+
+ union d2i *p = (union d2i *) unaligned_ptr;
+ union d2i u;
+
+ u.i[0] = p->i[0];
+ u.i[1] = p->i[1];
+
+ return u.d;
}
- If the value of `y' is always 1, 2 or 3, then `x' is always
- initialized, but GCC doesn't know this. Here is another common
- case:
+ Storing into the pointer can be done likewise with the same union.
+
+ * On Solaris, the `malloc' function in the `libmalloc.a' library may
+ allocate memory that is only 4 byte aligned. Since GCC on the
+ Sparc assumes that doubles are 8 byte aligned, this may result in a
+ fatal signal if doubles are stored in memory allocated by the
+ `libmalloc.a' library.
+
+ The solution is to not use the `libmalloc.a' library. Use instead
+ `malloc' and related functions from `libc.a'; they do not have
+ this problem.
+
+ * Sun forgot to include a static version of `libdl.a' with some
+ versions of SunOS (mainly 4.1). This results in undefined symbols
+ when linking static binaries (that is, if you use `-static'). If
+ you see undefined symbols `_dlclose', `_dlsym' or `_dlopen' when
+ linking, compile and link against the file `mit/util/misc/dlsym.c'
+ from the MIT version of X windows.
+
+ * The 128-bit long double format that the Sparc port supports
+ currently works by using the architecturally defined quad-word
+ floating point instructions. Since there is no hardware that
+ supports these instructions they must be emulated by the operating
+ system. Long doubles do not work in Sun OS versions 4.0.3 and
+ earlier, because the kernel emulator uses an obsolete and
+ incompatible format. Long doubles do not work in Sun OS version
+ 4.1.1 due to a problem in a Sun library. Long doubles do work on
+ Sun OS versions 4.1.2 and higher, but GCC does not enable them by
+ default. Long doubles appear to work in Sun OS 5.x (Solaris 2.x).
+
+ * On HP-UX version 9.01 on the HP PA, the HP compiler `cc' does not
+ compile GCC correctly. We do not yet know why. However, GCC
+ compiled on earlier HP-UX versions works properly on HP-UX 9.01
+ and can compile itself properly on 9.01.
+
+ * On the HP PA machine, ADB sometimes fails to work on functions
+ compiled with GCC. Specifically, it fails to work on functions
+ that use `alloca' or variable-size arrays. This is because GCC
+ doesn't generate HP-UX unwind descriptors for such functions. It
+ may even be impossible to generate them.
+
+ * Debugging (`-g') is not supported on the HP PA machine, unless you
+ use the preliminary GNU tools.
+
+ * Taking the address of a label may generate errors from the HP-UX
+ PA assembler. GAS for the PA does not have this problem.
+
+ * Using floating point parameters for indirect calls to static
+ functions will not work when using the HP assembler. There simply
+ is no way for GCC to specify what registers hold arguments for
+ static functions when using the HP assembler. GAS for the PA does
+ not have this problem.
+
+ * In extremely rare cases involving some very large functions you may
+ receive errors from the HP linker complaining about an out of
+ bounds unconditional branch offset. This used to occur more often
+ in previous versions of GCC, but is now exceptionally rare. If
+ you should run into it, you can work around by making your
+ function smaller.
+
+ * GCC compiled code sometimes emits warnings from the HP-UX
+ assembler of the form:
+
+ (warning) Use of GR3 when
+ frame >= 8192 may cause conflict.
+
+ These warnings are harmless and can be safely ignored.
+
+ * On the IBM RS/6000, compiling code of the form
+
+ extern int foo;
+
+ ... foo ...
+
+ static int foo;
+
+ will cause the linker to report an undefined symbol `foo'.
+ Although this behavior differs from most other systems, it is not a
+ bug because redefining an `extern' variable as `static' is
+ undefined in ISO C.
+
+ * In extremely rare cases involving some very large functions you may
+ receive errors from the AIX Assembler complaining about a
+ displacement that is too large. If you should run into it, you
+ can work around by making your function smaller.
+
+ * The `libstdc++.a' library in GCC relies on the SVR4 dynamic linker
+ semantics which merges global symbols between libraries and
+ applications, especially necessary for C++ streams functionality.
+ This is not the default behavior of AIX shared libraries and
+ dynamic linking. `libstdc++.a' is built on AIX with
+ "runtime-linking" enabled so that symbol merging can occur. To
+ utilize this feature, the application linked with `libstdc++.a'
+ must include the `-Wl,-brtl' flag on the link line. G++ cannot
+ impose this because this option may interfere with the semantics
+ of the user program and users may not always use `g++' to link his
+ or her application. Applications are not required to use the
+ `-Wl,-brtl' flag on the link line--the rest of the `libstdc++.a'
+ library which is not dependent on the symbol merging semantics
+ will continue to function correctly.
+
+ * An application can interpose its own definition of functions for
+ functions invoked by `libstdc++.a' with "runtime-linking" enabled
+ on AIX. To accomplish this the application must be linked with
+ "runtime-linking" option and the functions explicitly must be
+ exported by the application (`-Wl,-brtl,-bE:exportfile').
+
+ * AIX on the RS/6000 provides support (NLS) for environments outside
+ of the United States. Compilers and assemblers use NLS to support
+ locale-specific representations of various objects including
+ floating-point numbers (`.' vs `,' for separating decimal
+ fractions). There have been problems reported where the library
+ linked with GCC does not produce the same floating-point formats
+ that the assembler accepts. If you have this problem, set the
+ `LANG' environment variable to `C' or `En_US'.
+
+ * Even if you specify `-fdollars-in-identifiers', you cannot
+ successfully use `$' in identifiers on the RS/6000 due to a
+ restriction in the IBM assembler. GAS supports these identifiers.
+
+ * There is an assembler bug in versions of DG/UX prior to 5.4.2.01
+ that occurs when the `fldcr' instruction is used. GCC uses
+ `fldcr' on the 88100 to serialize volatile memory references. Use
+ the option `-mno-serialize-volatile' if your version of the
+ assembler has this bug.
+
+ * On VMS, GAS versions 1.38.1 and earlier may cause spurious warning
+ messages from the linker. These warning messages complain of
+ mismatched psect attributes. You can ignore them.
+
+ * On NewsOS version 3, if you include both of the files `stddef.h'
+ and `sys/types.h', you get an error because there are two typedefs
+ of `size_t'. You should change `sys/types.h' by adding these
+ lines around the definition of `size_t':
+
+ #ifndef _SIZE_T
+ #define _SIZE_T
+ ACTUAL-TYPEDEF-HERE
+ #endif
+
+ * On the Alliant, the system's own convention for returning
+ structures and unions is unusual, and is not compatible with GCC
+ no matter what options are used.
+
+ * On the IBM RT PC, the MetaWare HighC compiler (hc) uses a different
+ convention for structure and union returning. Use the option
+ `-mhc-struct-return' to tell GCC to use a convention compatible
+ with it.
+
+ * On Ultrix, the Fortran compiler expects registers 2 through 5 to
+ be saved by function calls. However, the C compiler uses
+ conventions compatible with BSD Unix: registers 2 through 5 may be
+ clobbered by function calls.
+
+ GCC uses the same convention as the Ultrix C compiler. You can use
+ these options to produce code compatible with the Fortran compiler:
+
+ -fcall-saved-r2 -fcall-saved-r3 -fcall-saved-r4 -fcall-saved-r5
+
+ * On the WE32k, you may find that programs compiled with GCC do not
+ work with the standard shared C library. You may need to link with
+ the ordinary C compiler. If you do so, you must specify the
+ following options:
+
+ -L/usr/local/lib/gcc-lib/we32k-att-sysv/2.8.1 -lgcc -lc_s
+
+ The first specifies where to find the library `libgcc.a' specified
+ with the `-lgcc' option.
+
+ GCC does linking by invoking `ld', just as `cc' does, and there is
+ no reason why it _should_ matter which compilation program you use
+ to invoke `ld'. If someone tracks this problem down, it can
+ probably be fixed easily.
+
+ * On the Alpha, you may get assembler errors about invalid syntax as
+ a result of floating point constants. This is due to a bug in the
+ C library functions `ecvt', `fcvt' and `gcvt'. Given valid
+ floating point numbers, they sometimes print `NaN'.
+
+ * On Irix 4.0.5F (and perhaps in some other versions), an assembler
+ bug sometimes reorders instructions incorrectly when optimization
+ is turned on. If you think this may be happening to you, try
+ using the GNU assembler; GAS version 2.1 supports ECOFF on Irix.
+
+ Or use the `-noasmopt' option when you compile GCC with itself,
+ and then again when you compile your program. (This is a temporary
+ kludge to turn off assembler optimization on Irix.) If this
+ proves to be what you need, edit the assembler spec in the file
+ `specs' so that it unconditionally passes `-O0' to the assembler,
+ and never passes `-O2' or `-O3'.
+\1f
+File: gcc.info, Node: External Bugs, Next: Incompatibilities, Prev: Interoperation, Up: Trouble
+
+10.4 Problems Compiling Certain Programs
+========================================
+
+Certain programs have problems compiling.
+
+ * Parse errors may occur compiling X11 on a Decstation running
+ Ultrix 4.2 because of problems in DEC's versions of the X11 header
+ files `X11/Xlib.h' and `X11/Xutil.h'. People recommend adding
+ `-I/usr/include/mit' to use the MIT versions of the header files,
+ using the `-traditional' switch to turn off ISO C, or fixing the
+ header files by adding this:
+
+ #ifdef __STDC__
+ #define NeedFunctionPrototypes 0
+ #endif
+
+ * On various 386 Unix systems derived from System V, including SCO,
+ ISC, and ESIX, you may get error messages about running out of
+ virtual memory while compiling certain programs.
+
+ You can prevent this problem by linking GCC with the GNU malloc
+ (which thus replaces the malloc that comes with the system). GNU
+ malloc is available as a separate package, and also in the file
+ `src/gmalloc.c' in the GNU Emacs 19 distribution.
+
+ If you have installed GNU malloc as a separate library package,
+ use this option when you relink GCC:
+
+ MALLOC=/usr/local/lib/libgmalloc.a
+
+ Alternatively, if you have compiled `gmalloc.c' from Emacs 19, copy
+ the object file to `gmalloc.o' and use this option when you relink
+ GCC:
+
+ MALLOC=gmalloc.o
+
+\1f
+File: gcc.info, Node: Incompatibilities, Next: Fixed Headers, Prev: External Bugs, Up: Trouble
+
+10.5 Incompatibilities of GCC
+=============================
+
+There are several noteworthy incompatibilities between GNU C and K&R
+(non-ISO) versions of C. The `-traditional' option eliminates many of
+these incompatibilities, _but not all_, by telling GCC to behave like a
+K&R C compiler.
+
+ * GCC normally makes string constants read-only. If several
+ identical-looking string constants are used, GCC stores only one
+ copy of the string.
+
+ One consequence is that you cannot call `mktemp' with a string
+ constant argument. The function `mktemp' always alters the string
+ its argument points to.
+
+ Another consequence is that `sscanf' does not work on some systems
+ when passed a string constant as its format control string or
+ input. This is because `sscanf' incorrectly tries to write into
+ the string constant. Likewise `fscanf' and `scanf'.
+
+ The best solution to these problems is to change the program to use
+ `char'-array variables with initialization strings for these
+ purposes instead of string constants. But if this is not possible,
+ you can use the `-fwritable-strings' flag, which directs GCC to
+ handle string constants the same way most C compilers do.
+ `-traditional' also has this effect, among others.
+
+ * `-2147483648' is positive.
+
+ This is because 2147483648 cannot fit in the type `int', so
+ (following the ISO C rules) its data type is `unsigned long int'.
+ Negating this value yields 2147483648 again.
+
+ * GCC does not substitute macro arguments when they appear inside of
+ string constants. For example, the following macro in GCC
+
+ #define foo(a) "a"
+
+ will produce output `"a"' regardless of what the argument A is.
+
+ The `-traditional' option directs GCC to handle such cases (among
+ others) in the old-fashioned (non-ISO) fashion.
+
+ * When you use `setjmp' and `longjmp', the only automatic variables
+ guaranteed to remain valid are those declared `volatile'. This is
+ a consequence of automatic register allocation. Consider this
+ function:
+
+ jmp_buf j;
+
+ foo ()
{
- int save_y;
- if (change_y) save_y = y, y = new_y;
- ...
- if (change_y) y = save_y;
+ int a, b;
+
+ a = fun1 ();
+ if (setjmp (j))
+ return a;
+
+ a = fun2 ();
+ /* `longjmp (j)' may occur in `fun3'. */
+ return a + fun3 ();
}
- This has no bug because `save_y' is used only if it is set.
-
- This option also warns when a non-volatile automatic variable
- might be changed by a call to `longjmp'. These warnings as well
- are possible only in optimizing compilation.
-
- The compiler sees only the calls to `setjmp'. It cannot know
- where `longjmp' will be called; in fact, a signal handler could
- call it at any point in the code. As a result, you may get a
- warning even when there is in fact no problem because `longjmp'
- cannot in fact be called at the place which would cause a problem.
-
- Some spurious warnings can be avoided if you declare all the
- functions you use that never return as `noreturn'. *Note Function
- Attributes::.
-
-`-Wreorder (C++ only)'
- Warn when the order of member initializers given in the code does
- not match the order in which they must be executed. For instance:
-
-`-Wunknown-pragmas'
- Warn when a #pragma directive is encountered which is not
- understood by GCC. If this command line option is used, warnings
- will even be issued for unknown pragmas in system header files.
- This is not the case if the warnings were only enabled by the
- `-Wall' command line option.
-
-`-Wall'
- All of the above `-W' options combined. This enables all the
- warnings about constructions that some users consider
- questionable, and that are easy to avoid (or modify to prevent the
- warning), even in conjunction with macros.
-
-`-Wdiv-by-zero'
- Warn about compile-time integer division by zero. This is
- default. To inhibit the warning messages, use `-Wno-div-by-zero'.
- Floating point division by zero is not warned about, as it can be
- a legitimate way of obtaining infinities and NaNs.
-
-`-Wmultichar'
- Warn if a multicharacter constant (`'FOOF'') is used. This is
- default. To inhibit the warning messages, use `-Wno-multichar'.
- Usually they indicate a typo in the user's code, as they have
- implementation-defined values, and should not be used in portable
- code.
-
-`-Wsystem-headers'
- Print warning messages for constructs found in system header files.
- Warnings from system headers are normally suppressed, on the
- assumption that they usually do not indicate real problems and
- would only make the compiler output harder to read. Using this
- command line option tells GCC to emit warnings from system headers
- as if they occurred in user code. However, note that using
- `-Wall' in conjunction with this option will _not_ warn about
- unknown pragmas in system headers--for that, `-Wunknown-pragmas'
- must also be used.
-
- The following `-W...' options are not implied by `-Wall'. Some of
-them warn about constructions that users generally do not consider
-questionable, but which occasionally you might wish to check for;
-others warn about constructions that are necessary or hard to avoid in
-some cases, and there is no simple way to modify the code to suppress
-the warning.
-
-`-W'
- Print extra warning messages for these events:
-
- * A function can return either with or without a value.
- (Falling off the end of the function body is considered
- returning without a value.) For example, this function would
- evoke such a warning:
-
- foo (a)
- {
- if (a > 0)
- return a;
- }
-
- * An expression-statement or the left-hand side of a comma
- expression contains no side effects. To suppress the
- warning, cast the unused expression to void. For example, an
- expression such as `x[i,j]' will cause a warning, but
- `x[(void)i,j]' will not.
-
- * An unsigned value is compared against zero with `<' or `<='.
-
- * A comparison like `x<=y<=z' appears; this is equivalent to
- `(x<=y ? 1 : 0) <= z', which is a different interpretation
- from that of ordinary mathematical notation.
-
- * Storage-class specifiers like `static' are not the first
- things in a declaration. According to the C Standard, this
- usage is obsolescent.
-
- * The return type of a function has a type qualifier such as
- `const'. Such a type qualifier has no effect, since the
- value returned by a function is not an lvalue. (But don't
- warn about the GNU extension of `volatile void' return types.
- That extension will be warned about if `-pedantic' is
- specified.)
-
- * If `-Wall' or `-Wunused' is also specified, warn about unused
- arguments.
-
- * A comparison between signed and unsigned values could produce
- an incorrect result when the signed value is converted to
- unsigned. (But don't warn if `-Wno-sign-compare' is also
- specified.)
-
- * An aggregate has a partly bracketed initializer. For
- example, the following code would evoke such a warning,
- because braces are missing around the initializer for `x.h':
-
- struct s { int f, g; };
- struct t { struct s h; int i; };
- struct t x = { 1, 2, 3 };
-
- * An aggregate has an initializer which does not initialize all
- members. For example, the following code would cause such a
- warning, because `x.h' would be implicitly initialized to
- zero:
-
- struct s { int f, g, h; };
- struct s x = { 3, 4 };
-
-`-Wfloat-equal'
- Warn if floating point values are used in equality comparisons.
-
- The idea behind this is that sometimes it is convenient (for the
- programmer) to consider floating-point values as approximations to
- infinitely precise real numbers. If you are doing this, then you
- need to compute (by analysing the code, or in some other way) the
- maximum or likely maximum error that the computation introduces,
- and allow for it when performing comparisons (and when producing
- output, but that's a different problem). In particular, instead
- of testing for equality, you would check to see whether the two
- values have ranges that overlap; and this is done with the
- relational operators, so equality comparisons are probably
- mistaken.
-
-`-Wtraditional (C only)'
- Warn about certain constructs that behave differently in
- traditional and ISO C. Also warn about ISO C constructs that have
- no traditional C equivalent, and/or problematic constructs which
- should be avoided.
-
- * Macro parameters that appear within string literals in the
- macro body. In traditional C macro replacement takes place
- within string literals, but does not in ISO C.
-
- * In traditional C, some preprocessor directives did not exist.
- Traditional preprocessors would only consider a line to be a
- directive if the `#' appeared in column 1 on the line.
- Therefore `-Wtraditional' warns about directives that
- traditional C understands but would ignore because the `#'
- does not appear as the first character on the line. It also
- suggests you hide directives like `#pragma' not understood by
- traditional C by indenting them. Some traditional
- implementations would not recognize `#elif', so it suggests
- avoiding it altogether.
-
- * A function-like macro that appears without arguments.
-
- * The unary plus operator.
-
- * The `U' integer constant suffix, or the `F' or `L' floating
- point constant suffixes. (Traditional C does support the `L'
- suffix on integer constants.) Note, these suffixes appear in
- macros defined in the system headers of most modern systems,
- e.g. the `_MIN'/`_MAX' macros in `<limits.h>'. Use of these
- macros in user code might normally lead to spurious warnings,
- however gcc's integrated preprocessor has enough context to
- avoid warning in these cases.
-
- * A function declared external in one block and then used after
- the end of the block.
-
- * A `switch' statement has an operand of type `long'.
-
- * A non-`static' function declaration follows a `static' one.
- This construct is not accepted by some traditional C
- compilers.
-
- * The ISO type of an integer constant has a different width or
- signedness from its traditional type. This warning is only
- issued if the base of the constant is ten. I.e. hexadecimal
- or octal values, which typically represent bit patterns, are
- not warned about.
-
- * Usage of ISO string concatenation is detected.
-
- * Initialization of automatic aggregates.
-
- * Identifier conflicts with labels. Traditional C lacks a
- separate namespace for labels.
-
- * Initialization of unions. If the initializer is zero, the
- warning is omitted. This is done under the assumption that
- the zero initializer in user code appears conditioned on e.g.
- `__STDC__' to avoid missing initializer warnings and relies
- on default initialization to zero in the traditional C case.
-
- * Conversions by prototypes between fixed/floating point values
- and vice versa. The absence of these prototypes when
- compiling with traditional C would cause serious problems.
- This is a subset of the possible conversion warnings, for the
- full set use `-Wconversion'.
-
-`-Wundef'
- Warn if an undefined identifier is evaluated in an `#if' directive.
-
-`-Wshadow'
- Warn whenever a local variable shadows another local variable,
- parameter or global variable or whenever a built-in function is
- shadowed.
-
-`-Wlarger-than-LEN'
- Warn whenever an object of larger than LEN bytes is defined.
-
-`-Wpointer-arith'
- Warn about anything that depends on the "size of" a function type
- or of `void'. GNU C assigns these types a size of 1, for
- convenience in calculations with `void *' pointers and pointers to
- functions.
-
-`-Wbad-function-cast (C only)'
- Warn whenever a function call is cast to a non-matching type. For
- example, warn if `int malloc()' is cast to `anything *'.
-
-`-Wcast-qual'
- Warn whenever a pointer is cast so as to remove a type qualifier
- from the target type. For example, warn if a `const char *' is
- cast to an ordinary `char *'.
-
-`-Wcast-align'
- Warn whenever a pointer is cast such that the required alignment
- of the target is increased. For example, warn if a `char *' is
- cast to an `int *' on machines where integers can only be accessed
- at two- or four-byte boundaries.
-
-`-Wwrite-strings'
- When compiling C, give string constants the type `const
- char[LENGTH]' so that copying the address of one into a
- non-`const' `char *' pointer will get a warning; when compiling
- C++, warn about the deprecated conversion from string constants to
- `char *'. These warnings will help you find at compile time code
- that can try to write into a string constant, but only if you have
- been very careful about using `const' in declarations and
- prototypes. Otherwise, it will just be a nuisance; this is why we
- did not make `-Wall' request these warnings.
-
-`-Wconversion'
- Warn if a prototype causes a type conversion that is different
- from what would happen to the same argument in the absence of a
- prototype. This includes conversions of fixed point to floating
- and vice versa, and conversions changing the width or signedness
- of a fixed point argument except when the same as the default
- promotion.
-
- Also, warn if a negative integer constant expression is implicitly
- converted to an unsigned type. For example, warn about the
- assignment `x = -1' if `x' is unsigned. But do not warn about
- explicit casts like `(unsigned) -1'.
-
-`-Wsign-compare'
- Warn when a comparison between signed and unsigned values could
- produce an incorrect result when the signed value is converted to
- unsigned. This warning is also enabled by `-W'; to get the other
- warnings of `-W' without this warning, use `-W -Wno-sign-compare'.
-
-`-Waggregate-return'
- Warn if any functions that return structures or unions are defined
- or called. (In languages where you can return an array, this also
- elicits a warning.)
-
-`-Wstrict-prototypes (C only)'
- Warn if a function is declared or defined without specifying the
- argument types. (An old-style function definition is permitted
- without a warning if preceded by a declaration which specifies the
- argument types.)
-
-`-Wmissing-prototypes (C only)'
- Warn if a global function is defined without a previous prototype
- declaration. This warning is issued even if the definition itself
- provides a prototype. The aim is to detect global functions that
- fail to be declared in header files.
-
-`-Wmissing-declarations'
- Warn if a global function is defined without a previous
- declaration. Do so even if the definition itself provides a
- prototype. Use this option to detect global functions that are
- not declared in header files.
-
-`-Wmissing-noreturn'
- Warn about functions which might be candidates for attribute
- `noreturn'. Note these are only possible candidates, not absolute
- ones. Care should be taken to manually verify functions actually
- do not ever return before adding the `noreturn' attribute,
- otherwise subtle code generation bugs could be introduced. You
- will not get a warning for `main' in hosted C environments.
-
-`-Wmissing-format-attribute'
- If `-Wformat' is enabled, also warn about functions which might be
- candidates for `format' attributes. Note these are only possible
- candidates, not absolute ones. GCC will guess that `format'
- attributes might be appropriate for any function that calls a
- function like `vprintf' or `vscanf', but this might not always be
- the case, and some functions for which `format' attributes are
- appropriate may not be detected. This option has no effect unless
- `-Wformat' is enabled (possibly by `-Wall').
-
-`-Wno-deprecated-declarations'
- Do not warn about uses of functions, variables, and types marked as
- deprecated by using the `deprecated' attribute. (*note Function
- Attributes::, *note Variable Attributes::, *note Type
- Attributes::.)
-
-`-Wpacked'
- Warn if a structure is given the packed attribute, but the packed
- attribute has no effect on the layout or size of the structure.
- Such structures may be mis-aligned for little benefit. For
- instance, in this code, the variable `f.x' in `struct bar' will be
- misaligned even though `struct bar' does not itself have the
- packed attribute:
-
- struct foo {
- int x;
- char a, b, c, d;
- } __attribute__((packed));
- struct bar {
- char z;
- struct foo f;
- };
+ Here `a' may or may not be restored to its first value when the
+ `longjmp' occurs. If `a' is allocated in a register, then its
+ first value is restored; otherwise, it keeps the last value stored
+ in it.
+
+ If you use the `-W' option with the `-O' option, you will get a
+ warning when GCC thinks such a problem might be possible.
+
+ The `-traditional' option directs GCC to put variables in the
+ stack by default, rather than in registers, in functions that call
+ `setjmp'. This results in the behavior found in traditional C
+ compilers.
+
+ * Programs that use preprocessing directives in the middle of macro
+ arguments do not work with GCC. For example, a program like this
+ will not work:
+
+ foobar (
+ #define luser
+ hack)
+
+ ISO C does not permit such a construct. It would make sense to
+ support it when `-traditional' is used, but it is too much work to
+ implement.
+
+ * K&R compilers allow comments to cross over an inclusion boundary
+ (i.e. started in an include file and ended in the including file).
+ I think this would be quite ugly and can't imagine it could be
+ needed.
+
+ * Declarations of external variables and functions within a block
+ apply only to the block containing the declaration. In other
+ words, they have the same scope as any other declaration in the
+ same place.
+
+ In some other C compilers, a `extern' declaration affects all the
+ rest of the file even if it happens within a block.
+
+ The `-traditional' option directs GCC to treat all `extern'
+ declarations as global, like traditional compilers.
+
+ * In traditional C, you can combine `long', etc., with a typedef
+ name, as shown here:
+
+ typedef int foo;
+ typedef long foo bar;
+
+ In ISO C, this is not allowed: `long' and other type modifiers
+ require an explicit `int'. Because this criterion is expressed by
+ Bison grammar rules rather than C code, the `-traditional' flag
+ cannot alter it.
+
+ * PCC allows typedef names to be used as function parameters. The
+ difficulty described immediately above applies here too.
+
+ * When in `-traditional' mode, GCC allows the following erroneous
+ pair of declarations to appear together in a given scope:
+
+ typedef int foo;
+ typedef foo foo;
+
+ * GCC treats all characters of identifiers as significant, even when
+ in `-traditional' mode. According to K&R-1 (2.2), "No more than
+ the first eight characters are significant, although more may be
+ used.". Also according to K&R-1 (2.2), "An identifier is a
+ sequence of letters and digits; the first character must be a
+ letter. The underscore _ counts as a letter.", but GCC also
+ allows dollar signs in identifiers.
+
+ * PCC allows whitespace in the middle of compound assignment
+ operators such as `+='. GCC, following the ISO standard, does not
+ allow this. The difficulty described immediately above applies
+ here too.
+
+ * GCC complains about unterminated character constants inside of
+ preprocessing conditionals that fail. Some programs have English
+ comments enclosed in conditionals that are guaranteed to fail; if
+ these comments contain apostrophes, GCC will probably report an
+ error. For example, this code would produce an error:
+
+ #if 0
+ You can't expect this to work.
+ #endif
+
+ The best solution to such a problem is to put the text into an
+ actual C comment delimited by `/*...*/'. However, `-traditional'
+ suppresses these error messages.
+
+ * Many user programs contain the declaration `long time ();'. In the
+ past, the system header files on many systems did not actually
+ declare `time', so it did not matter what type your program
+ declared it to return. But in systems with ISO C headers, `time'
+ is declared to return `time_t', and if that is not the same as
+ `long', then `long time ();' is erroneous.
+
+ The solution is to change your program to use appropriate system
+ headers (`<time.h>' on systems with ISO C headers) and not to
+ declare `time' if the system header files declare it, or failing
+ that to use `time_t' as the return type of `time'.
+
+ * When compiling functions that return `float', PCC converts it to a
+ double. GCC actually returns a `float'. If you are concerned
+ with PCC compatibility, you should declare your functions to return
+ `double'; you might as well say what you mean.
+
+ * When compiling functions that return structures or unions, GCC
+ output code normally uses a method different from that used on most
+ versions of Unix. As a result, code compiled with GCC cannot call
+ a structure-returning function compiled with PCC, and vice versa.
+
+ The method used by GCC is as follows: a structure or union which is
+ 1, 2, 4 or 8 bytes long is returned like a scalar. A structure or
+ union with any other size is stored into an address supplied by
+ the caller (usually in a special, fixed register, but on some
+ machines it is passed on the stack). The machine-description
+ macros `STRUCT_VALUE' and `STRUCT_INCOMING_VALUE' tell GCC where
+ to pass this address.
+
+ By contrast, PCC on most target machines returns structures and
+ unions of any size by copying the data into an area of static
+ storage, and then returning the address of that storage as if it
+ were a pointer value. The caller must copy the data from that
+ memory area to the place where the value is wanted. GCC does not
+ use this method because it is slower and nonreentrant.
+
+ On some newer machines, PCC uses a reentrant convention for all
+ structure and union returning. GCC on most of these machines uses
+ a compatible convention when returning structures and unions in
+ memory, but still returns small structures and unions in registers.
+
+ You can tell GCC to use a compatible convention for all structure
+ and union returning with the option `-fpcc-struct-return'.
+
+ * GCC complains about program fragments such as `0x74ae-0x4000'
+ which appear to be two hexadecimal constants separated by the minus
+ operator. Actually, this string is a single "preprocessing token".
+ Each such token must correspond to one token in C. Since this
+ does not, GCC prints an error message. Although it may appear
+ obvious that what is meant is an operator and two values, the ISO
+ C standard specifically requires that this be treated as erroneous.
+
+ A "preprocessing token" is a "preprocessing number" if it begins
+ with a digit and is followed by letters, underscores, digits,
+ periods and `e+', `e-', `E+', `E-', `p+', `p-', `P+', or `P-'
+ character sequences. (In strict C89 mode, the sequences `p+',
+ `p-', `P+' and `P-' cannot appear in preprocessing numbers.)
+
+ To make the above program fragment valid, place whitespace in
+ front of the minus sign. This whitespace will end the
+ preprocessing number.
+
+\1f
+File: gcc.info, Node: Fixed Headers, Next: Standard Libraries, Prev: Incompatibilities, Up: Trouble
+
+10.6 Fixed Header Files
+=======================
+
+GCC needs to install corrected versions of some system header files.
+This is because most target systems have some header files that won't
+work with GCC unless they are changed. Some have bugs, some are
+incompatible with ISO C, and some depend on special features of other
+compilers.
+
+ Installing GCC automatically creates and installs the fixed header
+files, by running a program called `fixincludes' (or for certain
+targets an alternative such as `fixinc.svr4'). Normally, you don't
+need to pay attention to this. But there are cases where it doesn't do
+the right thing automatically.
+
+ * If you update the system's header files, such as by installing a
+ new system version, the fixed header files of GCC are not
+ automatically updated. The easiest way to update them is to
+ reinstall GCC. (If you want to be clever, look in the makefile
+ and you can find a shortcut.)
+
+ * On some systems, in particular SunOS 4, header file directories
+ contain machine-specific symbolic links in certain places. This
+ makes it possible to share most of the header files among hosts
+ running the same version of SunOS 4 on different machine models.
+
+ The programs that fix the header files do not understand this
+ special way of using symbolic links; therefore, the directory of
+ fixed header files is good only for the machine model used to
+ build it.
+
+ In SunOS 4, only programs that look inside the kernel will notice
+ the difference between machine models. Therefore, for most
+ purposes, you need not be concerned about this.
+
+ It is possible to make separate sets of fixed header files for the
+ different machine models, and arrange a structure of symbolic
+ links so as to use the proper set, but you'll have to do this by
+ hand.
+
+ * On Lynxos, GCC by default does not fix the header files. This is
+ because bugs in the shell cause the `fixincludes' script to fail.
+
+ This means you will encounter problems due to bugs in the system
+ header files. It may be no comfort that they aren't GCC's fault,
+ but it does mean that there's nothing for us to do about them.
+
+\1f
+File: gcc.info, Node: Standard Libraries, Next: Disappointments, Prev: Fixed Headers, Up: Trouble
+
+10.7 Standard Libraries
+=======================
+
+GCC by itself attempts to be a conforming freestanding implementation.
+*Note Language Standards Supported by GCC: Standards, for details of
+what this means. Beyond the library facilities required of such an
+implementation, the rest of the C library is supplied by the vendor of
+the operating system. If that C library doesn't conform to the C
+standards, then your programs might get warnings (especially when using
+`-Wall') that you don't expect.
+
+ For example, the `sprintf' function on SunOS 4.1.3 returns `char *'
+while the C standard says that `sprintf' returns an `int'. The
+`fixincludes' program could make the prototype for this function match
+the Standard, but that would be wrong, since the function will still
+return `char *'.
+
+ If you need a Standard compliant library, then you need to find one,
+as GCC does not provide one. The GNU C library (called `glibc')
+provides ISO C, POSIX, BSD, SystemV and X/Open compatibility for
+GNU/Linux and HURD-based GNU systems; no recent version of it supports
+other systems, though some very old versions did. Version 2.2 of the
+GNU C library includes nearly complete C99 support. You could also ask
+your operating system vendor if newer libraries are available.
+
+\1f
+File: gcc.info, Node: Disappointments, Next: C++ Misunderstandings, Prev: Standard Libraries, Up: Trouble
+
+10.8 Disappointments and Misunderstandings
+==========================================
+
+These problems are perhaps regrettable, but we don't know any practical
+way around them.
+
+ * Certain local variables aren't recognized by debuggers when you
+ compile with optimization.
+
+ This occurs because sometimes GCC optimizes the variable out of
+ existence. There is no way to tell the debugger how to compute the
+ value such a variable "would have had", and it is not clear that
+ would be desirable anyway. So GCC simply does not mention the
+ eliminated variable when it writes debugging information.
+
+ You have to expect a certain amount of disagreement between the
+ executable and your source code, when you use optimization.
+
+ * Users often think it is a bug when GCC reports an error for code
+ like this:
+
+ int foo (struct mumble *);
+
+ struct mumble { ... };
+
+ int foo (struct mumble *x)
+ { ... }
+
+ This code really is erroneous, because the scope of `struct
+ mumble' in the prototype is limited to the argument list
+ containing it. It does not refer to the `struct mumble' defined
+ with file scope immediately below--they are two unrelated types
+ with similar names in different scopes.
+
+ But in the definition of `foo', the file-scope type is used
+ because that is available to be inherited. Thus, the definition
+ and the prototype do not match, and you get an error.
+
+ This behavior may seem silly, but it's what the ISO standard
+ specifies. It is easy enough for you to make your code work by
+ moving the definition of `struct mumble' above the prototype.
+ It's not worth being incompatible with ISO C just to avoid an
+ error for the example shown above.
+
+ * Accesses to bit-fields even in volatile objects works by accessing
+ larger objects, such as a byte or a word. You cannot rely on what
+ size of object is accessed in order to read or write the
+ bit-field; it may even vary for a given bit-field according to the
+ precise usage.
+
+ If you care about controlling the amount of memory that is
+ accessed, use volatile but do not use bit-fields.
+
+ * GCC comes with shell scripts to fix certain known problems in
+ system header files. They install corrected copies of various
+ header files in a special directory where only GCC will normally
+ look for them. The scripts adapt to various systems by searching
+ all the system header files for the problem cases that we know
+ about.
+
+ If new system header files are installed, nothing automatically
+ arranges to update the corrected header files. You will have to
+ reinstall GCC to fix the new header files. More specifically, go
+ to the build directory and delete the files `stmp-fixinc' and
+ `stmp-headers', and the subdirectory `include'; then do `make
+ install' again.
+
+ * On 68000 and x86 systems, for instance, you can get paradoxical
+ results if you test the precise values of floating point numbers.
+ For example, you can find that a floating point value which is not
+ a NaN is not equal to itself. This results from the fact that the
+ floating point registers hold a few more bits of precision than
+ fit in a `double' in memory. Compiled code moves values between
+ memory and floating point registers at its convenience, and moving
+ them into memory truncates them.
+
+ You can partially avoid this problem by using the `-ffloat-store'
+ option (*note Optimize Options::).
+
+ * On the MIPS, variable argument functions using `varargs.h' cannot
+ have a floating point value for the first argument. The reason
+ for this is that in the absence of a prototype in scope, if the
+ first argument is a floating point, it is passed in a floating
+ point register, rather than an integer register.
+
+ If the code is rewritten to use the ISO standard `stdarg.h' method
+ of variable arguments, and the prototype is in scope at the time
+ of the call, everything will work fine.
+
+ * On the H8/300 and H8/300H, variable argument functions must be
+ implemented using the ISO standard `stdarg.h' method of variable
+ arguments. Furthermore, calls to functions using `stdarg.h'
+ variable arguments must have a prototype for the called function
+ in scope at the time of the call.
+
+ * On AIX and other platforms without weak symbol support, templates
+ need to be instantiated explicitly and symbols for static members
+ of templates will not be generated.
+
+\1f
+File: gcc.info, Node: C++ Misunderstandings, Next: Protoize Caveats, Prev: Disappointments, Up: Trouble
-`-Wpadded'
- Warn if padding is included in a structure, either to align an
- element of the structure or to align the whole structure.
- Sometimes when this happens it is possible to rearrange the fields
- of the structure to reduce the padding and so make the structure
- smaller.
-
-`-Wredundant-decls'
- Warn if anything is declared more than once in the same scope,
- even in cases where multiple declaration is valid and changes
- nothing.
-
-`-Wnested-externs (C only)'
- Warn if an `extern' declaration is encountered within a function.
-
-`-Wunreachable-code'
- Warn if the compiler detects that code will never be executed.
-
- This option is intended to warn when the compiler detects that at
- least a whole line of source code will never be executed, because
- some condition is never satisfied or because it is after a
- procedure that never returns.
-
- It is possible for this option to produce a warning even though
- there are circumstances under which part of the affected line can
- be executed, so care should be taken when removing
- apparently-unreachable code.
-
- For instance, when a function is inlined, a warning may mean that
- the line is unreachable in only one inlined copy of the function.
-
- This option is not made part of `-Wall' because in a debugging
- version of a program there is often substantial code which checks
- correct functioning of the program and is, hopefully, unreachable
- because the program does work. Another common use of unreachable
- code is to provide behavior which is selectable at compile-time.
-
-`-Winline'
- Warn if a function can not be inlined and it was declared as
- inline.
-
-`-Wlong-long'
- Warn if `long long' type is used. This is default. To inhibit
- the warning messages, use `-Wno-long-long'. Flags `-Wlong-long'
- and `-Wno-long-long' are taken into account only when `-pedantic'
- flag is used.
-
-`-Wdisabled-optimization'
- Warn if a requested optimization pass is disabled. This warning
- does not generally indicate that there is anything wrong with your
- code; it merely indicates that GCC's optimizers were unable to
- handle the code effectively. Often, the problem is that your code
- is too big or too complex; GCC will refuse to optimize programs
- when the optimization itself is likely to take inordinate amounts
- of time.
-
-`-Werror'
- Make all warnings into errors.
+10.9 Common Misunderstandings with GNU C++
+==========================================
+
+C++ is a complex language and an evolving one, and its standard
+definition (the ISO C++ standard) was only recently completed. As a
+result, your C++ compiler may occasionally surprise you, even when its
+behavior is correct. This section discusses some areas that frequently
+give rise to questions of this sort.
+
+* Menu:
+
+* Static Definitions:: Static member declarations are not definitions
+* Temporaries:: Temporaries may vanish before you expect
+* Copy Assignment:: Copy Assignment operators copy virtual bases twice
+
+\1f
+File: gcc.info, Node: Static Definitions, Next: Temporaries, Up: C++ Misunderstandings
+
+10.9.1 Declare _and_ Define Static Members
+------------------------------------------
+
+When a class has static data members, it is not enough to _declare_ the
+static member; you must also _define_ it. For example:
+
+ class Foo
+ {
+ ...
+ void method();
+ static int bar;
+ };
+
+ This declaration only establishes that the class `Foo' has an `int'
+named `Foo::bar', and a member function named `Foo::method'. But you
+still need to define _both_ `method' and `bar' elsewhere. According to
+the ISO standard, you must supply an initializer in one (and only one)
+source file, such as:
+
+ int Foo::bar = 0;
+
+ Other C++ compilers may not correctly implement the standard
+behavior. As a result, when you switch to `g++' from one of these
+compilers, you may discover that a program that appeared to work
+correctly in fact does not conform to the standard: `g++' reports as
+undefined symbols any static data members that lack definitions.
+
+\1f
+File: gcc.info, Node: Temporaries, Next: Copy Assignment, Prev: Static Definitions, Up: C++ Misunderstandings
+
+10.9.2 Temporaries May Vanish Before You Expect
+-----------------------------------------------
+
+It is dangerous to use pointers or references to _portions_ of a
+temporary object. The compiler may very well delete the object before
+you expect it to, leaving a pointer to garbage. The most common place
+where this problem crops up is in classes like string classes,
+especially ones that define a conversion function to type `char *' or
+`const char *'--which is one reason why the standard `string' class
+requires you to call the `c_str' member function. However, any class
+that returns a pointer to some internal structure is potentially
+subject to this problem.
+
+ For example, a program may use a function `strfunc' that returns
+`string' objects, and another function `charfunc' that operates on
+pointers to `char':
+
+ string strfunc ();
+ void charfunc (const char *);
+
+ void
+ f ()
+ {
+ const char *p = strfunc().c_str();
+ ...
+ charfunc (p);
+ ...
+ charfunc (p);
+ }
+
+In this situation, it may seem reasonable to save a pointer to the C
+string returned by the `c_str' member function and use that rather than
+call `c_str' repeatedly. However, the temporary string created by the
+call to `strfunc' is destroyed after `p' is initialized, at which point
+`p' is left pointing to freed memory.
+
+ Code like this may run successfully under some other compilers,
+particularly obsolete cfront-based compilers that delete temporaries
+along with normal local variables. However, the GNU C++ behavior is
+standard-conforming, so if your program depends on late destruction of
+temporaries it is not portable.
+
+ The safe way to write such code is to give the temporary a name,
+which forces it to remain until the end of the scope of the name. For
+example:
+
+ string& tmp = strfunc ();
+ charfunc (tmp.c_str ());
+
+\1f
+File: gcc.info, Node: Copy Assignment, Prev: Temporaries, Up: C++ Misunderstandings
+
+10.9.3 Implicit Copy-Assignment for Virtual Bases
+-------------------------------------------------
+
+When a base class is virtual, only one subobject of the base class
+belongs to each full object. Also, the constructors and destructors are
+invoked only once, and called from the most-derived class. However,
+such objects behave unspecified when being assigned. For example:
+
+ struct Base{
+ char *name;
+ Base(char *n) : name(strdup(n)){}
+ Base& operator= (const Base& other){
+ free (name);
+ name = strdup (other.name);
+ }
+ };
+
+ struct A:virtual Base{
+ int val;
+ A():Base("A"){}
+ };
+
+ struct B:virtual Base{
+ int bval;
+ B():Base("B"){}
+ };
+
+ struct Derived:public A, public B{
+ Derived():Base("Derived"){}
+ };
+
+ void func(Derived &d1, Derived &d2)
+ {
+ d1 = d2;
+ }
+
+ The C++ standard specifies that `Base::Base' is only called once
+when constructing or copy-constructing a Derived object. It is
+unspecified whether `Base::operator=' is called more than once when the
+implicit copy-assignment for Derived objects is invoked (as it is
+inside `func' in the example).
+
+ g++ implements the "intuitive" algorithm for copy-assignment: assign
+all direct bases, then assign all members. In that algorithm, the
+virtual base subobject can be encountered many times. In the example,
+copying proceeds in the following order: `val', `name' (via `strdup'),
+`bval', and `name' again.
+
+ If application code relies on copy-assignment, a user-defined
+copy-assignment operator removes any uncertainties. With such an
+operator, the application can define whether and how the virtual base
+subobject is assigned.
+
+\1f
+File: gcc.info, Node: Protoize Caveats, Next: Non-bugs, Prev: C++ Misunderstandings, Up: Trouble
+
+10.10 Caveats of using `protoize'
+=================================
+
+The conversion programs `protoize' and `unprotoize' can sometimes
+change a source file in a way that won't work unless you rearrange it.
+
+ * `protoize' can insert references to a type name or type tag before
+ the definition, or in a file where they are not defined.
+
+ If this happens, compiler error messages should show you where the
+ new references are, so fixing the file by hand is straightforward.
+
+ * There are some C constructs which `protoize' cannot figure out.
+ For example, it can't determine argument types for declaring a
+ pointer-to-function variable; this you must do by hand. `protoize'
+ inserts a comment containing `???' each time it finds such a
+ variable; so you can find all such variables by searching for this
+ string. ISO C does not require declaring the argument types of
+ pointer-to-function types.
+
+ * Using `unprotoize' can easily introduce bugs. If the program
+ relied on prototypes to bring about conversion of arguments, these
+ conversions will not take place in the program without prototypes.
+ One case in which you can be sure `unprotoize' is safe is when you
+ are removing prototypes that were made with `protoize'; if the
+ program worked before without any prototypes, it will work again
+ without them.
+
+ You can find all the places where this problem might occur by
+ compiling the program with the `-Wconversion' option. It prints a
+ warning whenever an argument is converted.
+
+ * Both conversion programs can be confused if there are macro calls
+ in and around the text to be converted. In other words, the
+ standard syntax for a declaration or definition must not result
+ from expanding a macro. This problem is inherent in the design of
+ C and cannot be fixed. If only a few functions have confusing
+ macro calls, you can easily convert them manually.
+
+ * `protoize' cannot get the argument types for a function whose
+ definition was not actually compiled due to preprocessing
+ conditionals. When this happens, `protoize' changes nothing in
+ regard to such a function. `protoize' tries to detect such
+ instances and warn about them.
+
+ You can generally work around this problem by using `protoize' step
+ by step, each time specifying a different set of `-D' options for
+ compilation, until all of the functions have been converted.
+ There is no automatic way to verify that you have got them all,
+ however.
+
+ * Confusion may result if there is an occasion to convert a function
+ declaration or definition in a region of source code where there
+ is more than one formal parameter list present. Thus, attempts to
+ convert code containing multiple (conditionally compiled) versions
+ of a single function header (in the same vicinity) may not produce
+ the desired (or expected) results.
+
+ If you plan on converting source files which contain such code, it
+ is recommended that you first make sure that each conditionally
+ compiled region of source code which contains an alternative
+ function header also contains at least one additional follower
+ token (past the final right parenthesis of the function header).
+ This should circumvent the problem.
+
+ * `unprotoize' can become confused when trying to convert a function
+ definition or declaration which contains a declaration for a
+ pointer-to-function formal argument which has the same name as the
+ function being defined or declared. We recommend you avoid such
+ choices of formal parameter names.
+
+ * You might also want to correct some of the indentation by hand and
+ break long lines. (The conversion programs don't write lines
+ longer than eighty characters in any case.)
+
+\1f
+File: gcc.info, Node: Non-bugs, Next: Warnings and Errors, Prev: Protoize Caveats, Up: Trouble
+
+10.11 Certain Changes We Don't Want to Make
+===========================================
+
+This section lists changes that people frequently request, but which we
+do not make because we think GCC is better without them.
+
+ * Checking the number and type of arguments to a function which has
+ an old-fashioned definition and no prototype.
+
+ Such a feature would work only occasionally--only for calls that
+ appear in the same file as the called function, following the
+ definition. The only way to check all calls reliably is to add a
+ prototype for the function. But adding a prototype eliminates the
+ motivation for this feature. So the feature is not worthwhile.
+
+ * Warning about using an expression whose type is signed as a shift
+ count.
+
+ Shift count operands are probably signed more often than unsigned.
+ Warning about this would cause far more annoyance than good.
+
+ * Warning about assigning a signed value to an unsigned variable.
+
+ Such assignments must be very common; warning about them would
+ cause more annoyance than good.
+
+ * Warning when a non-void function value is ignored.
+
+ Coming as I do from a Lisp background, I balk at the idea that
+ there is something dangerous about discarding a value. There are
+ functions that return values which some callers may find useful;
+ it makes no sense to clutter the program with a cast to `void'
+ whenever the value isn't useful.
+
+ * Making `-fshort-enums' the default.
+
+ This would cause storage layout to be incompatible with most other
+ C compilers. And it doesn't seem very important, given that you
+ can get the same result in other ways. The case where it matters
+ most is when the enumeration-valued object is inside a structure,
+ and in that case you can specify a field width explicitly.
+
+ * Making bit-fields unsigned by default on particular machines where
+ "the ABI standard" says to do so.
+
+ The ISO C standard leaves it up to the implementation whether a
+ bit-field declared plain `int' is signed or not. This in effect
+ creates two alternative dialects of C.
+
+ The GNU C compiler supports both dialects; you can specify the
+ signed dialect with `-fsigned-bitfields' and the unsigned dialect
+ with `-funsigned-bitfields'. However, this leaves open the
+ question of which dialect to use by default.
+
+ Currently, the preferred dialect makes plain bit-fields signed,
+ because this is simplest. Since `int' is the same as `signed int'
+ in every other context, it is cleanest for them to be the same in
+ bit-fields as well.
+
+ Some computer manufacturers have published Application Binary
+ Interface standards which specify that plain bit-fields should be
+ unsigned. It is a mistake, however, to say anything about this
+ issue in an ABI. This is because the handling of plain bit-fields
+ distinguishes two dialects of C. Both dialects are meaningful on
+ every type of machine. Whether a particular object file was
+ compiled using signed bit-fields or unsigned is of no concern to
+ other object files, even if they access the same bit-fields in the
+ same data structures.
+
+ A given program is written in one or the other of these two
+ dialects. The program stands a chance to work on most any machine
+ if it is compiled with the proper dialect. It is unlikely to work
+ at all if compiled with the wrong dialect.
+
+ Many users appreciate the GNU C compiler because it provides an
+ environment that is uniform across machines. These users would be
+ inconvenienced if the compiler treated plain bit-fields
+ differently on certain machines.
+
+ Occasionally users write programs intended only for a particular
+ machine type. On these occasions, the users would benefit if the
+ GNU C compiler were to support by default the same dialect as the
+ other compilers on that machine. But such applications are rare.
+ And users writing a program to run on more than one type of
+ machine cannot possibly benefit from this kind of compatibility.
+
+ This is why GCC does and will treat plain bit-fields in the same
+ fashion on all types of machines (by default).
+
+ There are some arguments for making bit-fields unsigned by default
+ on all machines. If, for example, this becomes a universal de
+ facto standard, it would make sense for GCC to go along with it.
+ This is something to be considered in the future.
+
+ (Of course, users strongly concerned about portability should
+ indicate explicitly in each bit-field whether it is signed or not.
+ In this way, they write programs which have the same meaning in
+ both C dialects.)
+
+ * Undefining `__STDC__' when `-ansi' is not used.
+
+ Currently, GCC defines `__STDC__' as long as you don't use
+ `-traditional'. This provides good results in practice.
+
+ Programmers normally use conditionals on `__STDC__' to ask whether
+ it is safe to use certain features of ISO C, such as function
+ prototypes or ISO token concatenation. Since plain `gcc' supports
+ all the features of ISO C, the correct answer to these questions is
+ "yes".
+
+ Some users try to use `__STDC__' to check for the availability of
+ certain library facilities. This is actually incorrect usage in
+ an ISO C program, because the ISO C standard says that a conforming
+ freestanding implementation should define `__STDC__' even though it
+ does not have the library facilities. `gcc -ansi -pedantic' is a
+ conforming freestanding implementation, and it is therefore
+ required to define `__STDC__', even though it does not come with
+ an ISO C library.
+
+ Sometimes people say that defining `__STDC__' in a compiler that
+ does not completely conform to the ISO C standard somehow violates
+ the standard. This is illogical. The standard is a standard for
+ compilers that claim to support ISO C, such as `gcc -ansi'--not
+ for other compilers such as plain `gcc'. Whatever the ISO C
+ standard says is relevant to the design of plain `gcc' without
+ `-ansi' only for pragmatic reasons, not as a requirement.
+
+ GCC normally defines `__STDC__' to be 1, and in addition defines
+ `__STRICT_ANSI__' if you specify the `-ansi' option, or a `-std'
+ option for strict conformance to some version of ISO C. On some
+ hosts, system include files use a different convention, where
+ `__STDC__' is normally 0, but is 1 if the user specifies strict
+ conformance to the C Standard. GCC follows the host convention
+ when processing system include files, but when processing user
+ files it follows the usual GNU C convention.
+
+ * Undefining `__STDC__' in C++.
+
+ Programs written to compile with C++-to-C translators get the
+ value of `__STDC__' that goes with the C compiler that is
+ subsequently used. These programs must test `__STDC__' to
+ determine what kind of C preprocessor that compiler uses: whether
+ they should concatenate tokens in the ISO C fashion or in the
+ traditional fashion.
+
+ These programs work properly with GNU C++ if `__STDC__' is defined.
+ They would not work otherwise.
+
+ In addition, many header files are written to provide prototypes
+ in ISO C but not in traditional C. Many of these header files can
+ work without change in C++ provided `__STDC__' is defined. If
+ `__STDC__' is not defined, they will all fail, and will all need
+ to be changed to test explicitly for C++ as well.
+
+ * Deleting "empty" loops.
+
+ Historically, GCC has not deleted "empty" loops under the
+ assumption that the most likely reason you would put one in a
+ program is to have a delay, so deleting them will not make real
+ programs run any faster.
+
+ However, the rationale here is that optimization of a nonempty loop
+ cannot produce an empty one, which holds for C but is not always
+ the case for C++.
+
+ Moreover, with `-funroll-loops' small "empty" loops are already
+ removed, so the current behavior is both sub-optimal and
+ inconsistent and will change in the future.
+
+ * Making side effects happen in the same order as in some other
+ compiler.
+
+ It is never safe to depend on the order of evaluation of side
+ effects. For example, a function call like this may very well
+ behave differently from one compiler to another:
+
+ void func (int, int);
+
+ int i = 2;
+ func (i++, i++);
+
+ There is no guarantee (in either the C or the C++ standard language
+ definitions) that the increments will be evaluated in any
+ particular order. Either increment might happen first. `func'
+ might get the arguments `2, 3', or it might get `3, 2', or even
+ `2, 2'.
+
+ * Not allowing structures with volatile fields in registers.
+
+ Strictly speaking, there is no prohibition in the ISO C standard
+ against allowing structures with volatile fields in registers, but
+ it does not seem to make any sense and is probably not what you
+ wanted to do. So the compiler will give an error message in this
+ case.
+
+ * Making certain warnings into errors by default.
+
+ Some ISO C testsuites report failure when the compiler does not
+ produce an error message for a certain program.
+
+ ISO C requires a "diagnostic" message for certain kinds of invalid
+ programs, but a warning is defined by GCC to count as a
+ diagnostic. If GCC produces a warning but not an error, that is
+ correct ISO C support. If test suites call this "failure", they
+ should be run with the GCC option `-pedantic-errors', which will
+ turn these warnings into errors.
+
+
+\1f
+File: gcc.info, Node: Warnings and Errors, Prev: Non-bugs, Up: Trouble
+
+10.12 Warning Messages and Error Messages
+=========================================
+
+The GNU compiler can produce two kinds of diagnostics: errors and
+warnings. Each kind has a different purpose:
+
+ "Errors" report problems that make it impossible to compile your
+ program. GCC reports errors with the source file name and line
+ number where the problem is apparent.
+
+ "Warnings" report other unusual conditions in your code that _may_
+ indicate a problem, although compilation can (and does) proceed.
+ Warning messages also report the source file name and line number,
+ but include the text `warning:' to distinguish them from error
+ messages.
+
+ Warnings may indicate danger points where you should check to make
+sure that your program really does what you intend; or the use of
+obsolete features; or the use of nonstandard features of GNU C or C++.
+Many warnings are issued only if you ask for them, with one of the `-W'
+options (for instance, `-Wall' requests a variety of useful warnings).
+
+ GCC always tries to compile your program if possible; it never
+gratuitously rejects a program whose meaning is clear merely because
+(for instance) it fails to conform to a standard. In some cases,
+however, the C and C++ standards specify that certain extensions are
+forbidden, and a diagnostic _must_ be issued by a conforming compiler.
+The `-pedantic' option tells GCC to issue warnings in such cases;
+`-pedantic-errors' says to make them errors instead. This does not
+mean that _all_ non-ISO constructs get warnings or errors.
+
+ *Note Options to Request or Suppress Warnings: Warning Options, for
+more detail on these and related command-line options.
+
+\1f
+File: gcc.info, Node: Bugs, Next: Service, Prev: Trouble, Up: Top
+
+11 Reporting Bugs
+*****************
+
+Your bug reports play an essential role in making GCC reliable.
+
+ When you encounter a problem, the first thing to do is to see if it
+is already known. *Note Trouble::. If it isn't known, then you should
+report the problem.
+
+ Reporting a bug may help you by bringing a solution to your problem,
+or it may not. (If it does not, look in the service directory; see
+*note Service::.) In any case, the principal function of a bug report
+is to help the entire community by making the next version of GCC work
+better. Bug reports are your contribution to the maintenance of GCC.
+
+ Since the maintainers are very overloaded, we cannot respond to every
+bug report. However, if the bug has not been fixed, we are likely to
+send you a patch and ask you to tell us whether it works.
+
+ In order for a bug report to serve its purpose, you must include the
+information that makes for fixing the bug.
+
+* Menu:
+
+* Criteria: Bug Criteria. Have you really found a bug?
+* Where: Bug Lists. Where to send your bug report.
+* Reporting: Bug Reporting. How to report a bug effectively.
+* GNATS: gccbug. You can use a bug reporting tool.
+* Known: Trouble. Known problems.
+* Help: Service. Where to ask for help.
+
+\1f
+File: gcc.info, Node: Bug Criteria, Next: Bug Lists, Up: Bugs
+
+11.1 Have You Found a Bug?
+==========================
+
+If you are not sure whether you have found a bug, here are some
+guidelines:
+
+ * If the compiler gets a fatal signal, for any input whatever, that
+ is a compiler bug. Reliable compilers never crash.
+
+ * If the compiler produces invalid assembly code, for any input
+ whatever (except an `asm' statement), that is a compiler bug,
+ unless the compiler reports errors (not just warnings) which would
+ ordinarily prevent the assembler from being run.
+
+ * If the compiler produces valid assembly code that does not
+ correctly execute the input source code, that is a compiler bug.
+
+ However, you must double-check to make sure, because you may have
+ run into an incompatibility between GNU C and traditional C (*note
+ Incompatibilities::). These incompatibilities might be considered
+ bugs, but they are inescapable consequences of valuable features.
+
+ Or you may have a program whose behavior is undefined, which
+ happened by chance to give the desired results with another C or
+ C++ compiler.
+
+ For example, in many nonoptimizing compilers, you can write `x;'
+ at the end of a function instead of `return x;', with the same
+ results. But the value of the function is undefined if `return'
+ is omitted; it is not a bug when GCC produces different results.
+
+ Problems often result from expressions with two increment
+ operators, as in `f (*p++, *p++)'. Your previous compiler might
+ have interpreted that expression the way you intended; GCC might
+ interpret it another way. Neither compiler is wrong. The bug is
+ in your code.
+
+ After you have localized the error to a single source line, it
+ should be easy to check for these things. If your program is
+ correct and well defined, you have found a compiler bug.
+
+ * If the compiler produces an error message for valid input, that is
+ a compiler bug.
+
+ * If the compiler does not produce an error message for invalid
+ input, that is a compiler bug. However, you should note that your
+ idea of "invalid input" might be my idea of "an extension" or
+ "support for traditional practice".
+
+ * If you are an experienced user of one of the languages GCC
+ supports, your suggestions for improvement of GCC are welcome in
+ any case.
+
+\1f
+File: gcc.info, Node: Bug Lists, Next: Bug Reporting, Prev: Bug Criteria, Up: Bugs
+
+11.2 Where to Report Bugs
+=========================
+
+Send bug reports for the GNU Compiler Collection to
+<gcc-bugs@gcc.gnu.org>. In accordance with the GNU-wide convention, in
+which bug reports for tool "foo" are sent to `bug-foo@gnu.org', the
+address <bug-gcc@gnu.org> may also be used; it will forward to the
+address given above.
+
+ Please read `http://gcc.gnu.org/bugs.html' for additional and/or
+more up-to-date bug reporting instructions before you post a bug report.
+
+\1f
+File: gcc.info, Node: Bug Reporting, Next: gccbug, Prev: Bug Lists, Up: Bugs
+
+11.3 How to Report Bugs
+=======================
+
+The fundamental principle of reporting bugs usefully is this: *report
+all the facts*. If you are not sure whether to state a fact or leave
+it out, state it!
+
+ Often people omit facts because they think they know what causes the
+problem and they conclude that some details don't matter. Thus, you
+might assume that the name of the variable you use in an example does
+not matter. Well, probably it doesn't, but one cannot be sure.
+Perhaps the bug is a stray memory reference which happens to fetch from
+the location where that name is stored in memory; perhaps, if the name
+were different, the contents of that location would fool the compiler
+into doing the right thing despite the bug. Play it safe and give a
+specific, complete example. That is the easiest thing for you to do,
+and the most helpful.
+
+ Keep in mind that the purpose of a bug report is to enable someone to
+fix the bug if it is not known. It isn't very important what happens if
+the bug is already known. Therefore, always write your bug reports on
+the assumption that the bug is not known.
+
+ Sometimes people give a few sketchy facts and ask, "Does this ring a
+bell?" This cannot help us fix a bug, so it is basically useless. We
+respond by asking for enough details to enable us to investigate. You
+might as well expedite matters by sending them to begin with.
+
+ Try to make your bug report self-contained. If we have to ask you
+for more information, it is best if you include all the previous
+information in your response, as well as the information that was
+missing.
+
+ Please report each bug in a separate message. This makes it easier
+for us to track which bugs have been fixed and to forward your bugs
+reports to the appropriate maintainer.
+
+ To enable someone to investigate the bug, you should include all
+these things:
+
+ * The version of GCC. You can get this by running it with the `-v'
+ option.
+
+ Without this, we won't know whether there is any point in looking
+ for the bug in the current version of GCC.
+
+ * A complete input file that will reproduce the bug. If the bug is
+ in the C preprocessor, send a source file and any header files
+ that it requires. If the bug is in the compiler proper (`cc1'),
+ send the preprocessor output generated by adding `-save-temps' to
+ the compilation command (*note Debugging Options::). When you do
+ this, use the same `-I', `-D' or `-U' options that you used in
+ actual compilation. Then send the INPUT.i or INPUT.ii files
+ generated.
+
+ A single statement is not enough of an example. In order to
+ compile it, it must be embedded in a complete file of compiler
+ input; and the bug might depend on the details of how this is done.
+
+ Without a real example one can compile, all anyone can do about
+ your bug report is wish you luck. It would be futile to try to
+ guess how to provoke the bug. For example, bugs in register
+ allocation and reloading frequently depend on every little detail
+ of the function they happen in.
+
+ Even if the input file that fails comes from a GNU program, you
+ should still send the complete test case. Don't ask the GCC
+ maintainers to do the extra work of obtaining the program in
+ question--they are all overworked as it is. Also, the problem may
+ depend on what is in the header files on your system; it is
+ unreliable for the GCC maintainers to try the problem with the
+ header files available to them. By sending CPP output, you can
+ eliminate this source of uncertainty and save us a certain
+ percentage of wild goose chases.
+
+ * The command arguments you gave GCC to compile that example and
+ observe the bug. For example, did you use `-O'? To guarantee you
+ won't omit something important, list all the options.
+
+ If we were to try to guess the arguments, we would probably guess
+ wrong and then we would not encounter the bug.
+
+ * The type of machine you are using, and the operating system name
+ and version number.
+
+ * The operands you gave to the `configure' command when you installed
+ the compiler.
+
+ * A complete list of any modifications you have made to the compiler
+ source. (We don't promise to investigate the bug unless it
+ happens in an unmodified compiler. But if you've made
+ modifications and don't tell us, then you are sending us on a wild
+ goose chase.)
+
+ Be precise about these changes. A description in English is not
+ enough--send a context diff for them.
+
+ Adding files of your own (such as a machine description for a
+ machine we don't support) is a modification of the compiler source.
+
+ * Details of any other deviations from the standard procedure for
+ installing GCC.
+
+ * A description of what behavior you observe that you believe is
+ incorrect. For example, "The compiler gets a fatal signal," or,
+ "The assembler instruction at line 208 in the output is incorrect."
+
+ Of course, if the bug is that the compiler gets a fatal signal,
+ then one can't miss it. But if the bug is incorrect output, the
+ maintainer might not notice unless it is glaringly wrong. None of
+ us has time to study all the assembler code from a 50-line C
+ program just on the chance that one instruction might be wrong.
+ We need _you_ to do this part!
+
+ Even if the problem you experience is a fatal signal, you should
+ still say so explicitly. Suppose something strange is going on,
+ such as, your copy of the compiler is out of synch, or you have
+ encountered a bug in the C library on your system. (This has
+ happened!) Your copy might crash and the copy here would not. If
+ you said to expect a crash, then when the compiler here fails to
+ crash, we would know that the bug was not happening. If you don't
+ say to expect a crash, then we would not know whether the bug was
+ happening. We would not be able to draw any conclusion from our
+ observations.
+
+ If the problem is a diagnostic when compiling GCC with some other
+ compiler, say whether it is a warning or an error.
+
+ Often the observed symptom is incorrect output when your program
+ is run. Sad to say, this is not enough information unless the
+ program is short and simple. None of us has time to study a large
+ program to figure out how it would work if compiled correctly,
+ much less which line of it was compiled wrong. So you will have
+ to do that. Tell us which source line it is, and what incorrect
+ result happens when that line is executed. A person who
+ understands the program can find this as easily as finding a bug
+ in the program itself.
+
+ * If you send examples of assembler code output from GCC, please use
+ `-g' when you make them. The debugging information includes
+ source line numbers which are essential for correlating the output
+ with the input.
+
+ * If you wish to mention something in the GCC source, refer to it by
+ context, not by line number.
+
+ The line numbers in the development sources don't match those in
+ your sources. Your line numbers would convey no useful
+ information to the maintainers.
+
+ * Additional information from a debugger might enable someone to
+ find a problem on a machine which he does not have available.
+ However, you need to think when you collect this information if
+ you want it to have any chance of being useful.
+
+ For example, many people send just a backtrace, but that is never
+ useful by itself. A simple backtrace with arguments conveys little
+ about GCC because the compiler is largely data-driven; the same
+ functions are called over and over for different RTL insns, doing
+ different things depending on the details of the insn.
+
+ Most of the arguments listed in the backtrace are useless because
+ they are pointers to RTL list structure. The numeric values of the
+ pointers, which the debugger prints in the backtrace, have no
+ significance whatever; all that matters is the contents of the
+ objects they point to (and most of the contents are other such
+ pointers).
+
+ In addition, most compiler passes consist of one or more loops that
+ scan the RTL insn sequence. The most vital piece of information
+ about such a loop--which insn it has reached--is usually in a
+ local variable, not in an argument.
+
+ What you need to provide in addition to a backtrace are the values
+ of the local variables for several stack frames up. When a local
+ variable or an argument is an RTX, first print its value and then
+ use the GDB command `pr' to print the RTL expression that it points
+ to. (If GDB doesn't run on your machine, use your debugger to call
+ the function `debug_rtx' with the RTX as an argument.) In
+ general, whenever a variable is a pointer, its value is no use
+ without the data it points to.
+
+ Here are some things that are not necessary:
+
+ * A description of the envelope of the bug.
+
+ Often people who encounter a bug spend a lot of time investigating
+ which changes to the input file will make the bug go away and which
+ changes will not affect it.
+
+ This is often time consuming and not very useful, because the way
+ we will find the bug is by running a single example under the
+ debugger with breakpoints, not by pure deduction from a series of
+ examples. You might as well save your time for something else.
+
+ Of course, if you can find a simpler example to report _instead_ of
+ the original one, that is a convenience. Errors in the output
+ will be easier to spot, running under the debugger will take less
+ time, etc. Most GCC bugs involve just one function, so the most
+ straightforward way to simplify an example is to delete all the
+ function definitions except the one where the bug occurs. Those
+ earlier in the file may be replaced by external declarations if
+ the crucial function depends on them. (Exception: inline
+ functions may affect compilation of functions defined later in the
+ file.)
+
+ However, simplification is not vital; if you don't want to do this,
+ report the bug anyway and send the entire test case you used.
+
+ * In particular, some people insert conditionals `#ifdef BUG' around
+ a statement which, if removed, makes the bug not happen. These
+ are just clutter; we won't pay any attention to them anyway.
+ Besides, you should send us cpp output, and that can't have
+ conditionals.
+
+ * A patch for the bug.
+
+ A patch for the bug is useful if it is a good one. But don't omit
+ the necessary information, such as the test case, on the
+ assumption that a patch is all we need. We might see problems
+ with your patch and decide to fix the problem another way, or we
+ might not understand it at all.
+
+ Sometimes with a program as complicated as GCC it is very hard to
+ construct an example that will make the program follow a certain
+ path through the code. If you don't send the example, we won't be
+ able to construct one, so we won't be able to verify that the bug
+ is fixed.
+
+ And if we can't understand what bug you are trying to fix, or why
+ your patch should be an improvement, we won't install it. A test
+ case will help us to understand.
+
+ See `http://gcc.gnu.org/contribute.html' for guidelines on how to
+ make it easy for us to understand and install your patches.
+
+ * A guess about what the bug is or what it depends on.
+
+ Such guesses are usually wrong. Even I can't guess right about
+ such things without first using the debugger to find the facts.
+
+ * A core dump file.
+
+ We have no way of examining a core dump for your type of machine
+ unless we have an identical system--and if we do have one, we
+ should be able to reproduce the crash ourselves.
+
+\1f
+File: gcc.info, Node: gccbug, Prev: Bug Reporting, Up: Bugs
+
+11.4 The gccbug script
+======================
+
+To simplify creation of bug reports, and to allow better tracking of
+reports, we use the GNATS bug tracking system. Part of that system is
+the `gccbug' script. This is a Unix shell script, so you need a shell
+to run it. It is normally installed in the same directory where `gcc'
+is installed.
+
+ The gccbug script is derived from send-pr, *note Creating new
+Problem Reports: (send-pr)using send-pr. When invoked, it starts a
+text editor so you can fill out the various fields of the report. When
+the you quit the editor, the report is automatically send to the bug
+reporting address.
+
+ A number of fields in this bug report form are specific to GCC, and
+are explained at `http://gcc.gnu.org/gnats.html'.
+
+\1f
+File: gcc.info, Node: Service, Next: Contributing, Prev: Bugs, Up: Top
+
+12 How To Get Help with GCC
+***************************
+
+If you need help installing, using or changing GCC, there are two ways
+to find it:
+
+ * Send a message to a suitable network mailing list. First try
+ <gcc-help@gcc.gnu.org> (for help installing or using GCC), and if
+ that brings no response, try <gcc@gcc.gnu.org>. For help changing
+ GCC, ask <gcc@gcc.gnu.org>. If you think you have found a bug in
+ GCC, please report it following the instructions at *note Bug
+ Reporting::.
+
+ * Look in the service directory for someone who might help you for a
+ fee. The service directory is found at
+ `http://www.gnu.org/prep/service.html'.
+
+\1f
+File: gcc.info, Node: Contributing, Next: VMS, Prev: Service, Up: Top
+
+13 Contributing to GCC Development
+**********************************
+
+If you would like to help pretest GCC releases to assure they work well,
+our current development sources are available by CVS (see
+`http://gcc.gnu.org/cvs.html'). Source and binary snapshots are also
+available for FTP; see `http://gcc.gnu.org/snapshots.html'.
+
+ If you would like to work on improvements to GCC, please read the
+advice at these URLs:
+
+ `http://gcc.gnu.org/contribute.html'
+ `http://gcc.gnu.org/contributewhy.html'
+
+for information on how to make useful contributions and avoid
+duplication of effort. Suggested projects are listed at
+`http://gcc.gnu.org/projects/'.
+
+\1f
+File: gcc.info, Node: VMS, Next: Funding, Prev: Contributing, Up: Top
+
+14 Using GCC on VMS
+*******************
+
+Here is how to use GCC on VMS.
+
+* Menu:
+
+* Include Files and VMS:: Where the preprocessor looks for the include files.
+* Global Declarations:: How to do globaldef, globalref and globalvalue with
+ GCC.
+* VMS Misc:: Misc information.
+
+\1f
+File: gcc.info, Node: Include Files and VMS, Next: Global Declarations, Up: VMS
+
+14.1 Include Files and VMS
+==========================
+
+Due to the differences between the filesystems of Unix and VMS, GCC
+attempts to translate file names in `#include' into names that VMS will
+understand. The basic strategy is to prepend a prefix to the
+specification of the include file, convert the whole filename to a VMS
+filename, and then try to open the file. GCC tries various prefixes
+one by one until one of them succeeds:
+
+ 1. The first prefix is the `GNU_CC_INCLUDE:' logical name: this is
+ where GNU C header files are traditionally stored. If you wish to
+ store header files in non-standard locations, then you can assign
+ the logical `GNU_CC_INCLUDE' to be a search list, where each
+ element of the list is suitable for use with a rooted logical.
+
+ 2. The next prefix tried is `SYS$SYSROOT:[SYSLIB.]'. This is where
+ VAX-C header files are traditionally stored.
+
+ 3. If the include file specification by itself is a valid VMS
+ filename, the preprocessor then uses this name with no prefix in
+ an attempt to open the include file.
+
+ 4. If the file specification is not a valid VMS filename (i.e. does
+ not contain a device or a directory specifier, and contains a `/'
+ character), the preprocessor tries to convert it from Unix syntax
+ to VMS syntax.
+
+ Conversion works like this: the first directory name becomes a
+ device, and the rest of the directories are converted into
+ VMS-format directory names. For example, the name `X11/foobar.h'
+ is translated to `X11:[000000]foobar.h' or `X11:foobar.h',
+ whichever one can be opened. This strategy allows you to assign a
+ logical name to point to the actual location of the header files.
+
+ 5. If none of these strategies succeeds, the `#include' fails.
+
+ Include directives of the form:
+
+ #include foobar
+
+are a common source of incompatibility between VAX-C and GCC. VAX-C
+treats this much like a standard `#include <foobar.h>' directive. That
+is incompatible with the ISO C behavior implemented by GCC: to expand
+the name `foobar' as a macro. Macro expansion should eventually yield
+one of the two standard formats for `#include':
+
+ #include "FILE"
+ #include <FILE>
+
+ If you have this problem, the best solution is to modify the source
+to convert the `#include' directives to one of the two standard forms.
+That will work with either compiler. If you want a quick and dirty fix,
+define the file names as macros with the proper expansion, like this:
+
+ #define stdio <stdio.h>
+
+This will work, as long as the name doesn't conflict with anything else
+in the program.
+
+ Another source of incompatibility is that VAX-C assumes that:
+
+ #include "foobar"
+
+is actually asking for the file `foobar.h'. GCC does not make this
+assumption, and instead takes what you ask for literally; it tries to
+read the file `foobar'. The best way to avoid this problem is to
+always specify the desired file extension in your include directives.
+
+ GCC for VMS is distributed with a set of include files that is
+sufficient to compile most general purpose programs. Even though the
+GCC distribution does not contain header files to define constants and
+structures for some VMS system-specific functions, there is no reason
+why you cannot use GCC with any of these functions. You first may have
+to generate or create header files, either by using the public domain
+utility `UNSDL' (which can be found on a DECUS tape), or by extracting
+the relevant modules from one of the system macro libraries, and using
+an editor to construct a C header file.
+
+ A `#include' file name cannot contain a DECNET node name. The
+preprocessor reports an I/O error if you attempt to use a node name,
+whether explicitly, or implicitly via a logical name.
+
+\1f
+File: gcc.info, Node: Global Declarations, Next: VMS Misc, Prev: Include Files and VMS, Up: VMS
+
+14.2 Global Declarations and VMS
+================================
+
+GCC does not provide the `globalref', `globaldef' and `globalvalue'
+keywords of VAX-C. You can get the same effect with an obscure feature
+of GAS, the GNU assembler. (This requires GAS version 1.39 or later.)
+The following macros allow you to use this feature in a fairly natural
+way:
+
+ #ifdef __GNUC__
+ #define GLOBALREF(TYPE,NAME) \
+ TYPE NAME \
+ asm ("_$$PsectAttributes_GLOBALSYMBOL$$" #NAME)
+ #define GLOBALDEF(TYPE,NAME,VALUE) \
+ TYPE NAME \
+ asm ("_$$PsectAttributes_GLOBALSYMBOL$$" #NAME) \
+ = VALUE
+ #define GLOBALVALUEREF(TYPE,NAME) \
+ const TYPE NAME[1] \
+ asm ("_$$PsectAttributes_GLOBALVALUE$$" #NAME)
+ #define GLOBALVALUEDEF(TYPE,NAME,VALUE) \
+ const TYPE NAME[1] \
+ asm ("_$$PsectAttributes_GLOBALVALUE$$" #NAME) \
+ = {VALUE}
+ #else
+ #define GLOBALREF(TYPE,NAME) \
+ globalref TYPE NAME
+ #define GLOBALDEF(TYPE,NAME,VALUE) \
+ globaldef TYPE NAME = VALUE
+ #define GLOBALVALUEDEF(TYPE,NAME,VALUE) \
+ globalvalue TYPE NAME = VALUE
+ #define GLOBALVALUEREF(TYPE,NAME) \
+ globalvalue TYPE NAME
+ #endif
+
+(The `_$$PsectAttributes_GLOBALSYMBOL' prefix at the start of the name
+is removed by the assembler, after it has modified the attributes of
+the symbol). These macros are provided in the VMS binaries
+distribution in a header file `GNU_HACKS.H'. An example of the usage
+is:
+
+ GLOBALREF (int, ijk);
+ GLOBALDEF (int, jkl, 0);
+
+ The macros `GLOBALREF' and `GLOBALDEF' cannot be used
+straightforwardly for arrays, since there is no way to insert the array
+dimension into the declaration at the right place. However, you can
+declare an array with these macros if you first define a typedef for the
+array type, like this:
+
+ typedef int intvector[10];
+ GLOBALREF (intvector, foo);
+
+ Array and structure initializers will also break the macros; you can
+define the initializer to be a macro of its own, or you can expand the
+`GLOBALDEF' macro by hand. You may find a case where you wish to use
+the `GLOBALDEF' macro with a large array, but you are not interested in
+explicitly initializing each element of the array. In such cases you
+can use an initializer like: `{0,}', which will initialize the entire
+array to `0'.
+
+ A shortcoming of this implementation is that a variable declared with
+`GLOBALVALUEREF' or `GLOBALVALUEDEF' is always an array. For example,
+the declaration:
+
+ GLOBALVALUEREF(int, ijk);
+
+declares the variable `ijk' as an array of type `int [1]'. This is
+done because a globalvalue is actually a constant; its "value" is what
+the linker would normally consider an address. That is not how an
+integer value works in C, but it is how an array works. So treating
+the symbol as an array name gives consistent results--with the
+exception that the value seems to have the wrong type. *Don't try to
+access an element of the array.* It doesn't have any elements. The
+array "address" may not be the address of actual storage.
+
+ The fact that the symbol is an array may lead to warnings where the
+variable is used. Insert type casts to avoid the warnings. Here is an
+example; it takes advantage of the ISO C feature allowing macros that
+expand to use the same name as the macro itself.
+
+ GLOBALVALUEREF (int, ss$_normal);
+ GLOBALVALUEDEF (int, xyzzy,123);
+ #ifdef __GNUC__
+ #define ss$_normal ((int) ss$_normal)
+ #define xyzzy ((int) xyzzy)
+ #endif
+
+ Don't use `globaldef' or `globalref' with a variable whose type is
+an enumeration type; this is not implemented. Instead, make the
+variable an integer, and use a `globalvaluedef' for each of the
+enumeration values. An example of this would be:
+
+ #ifdef __GNUC__
+ GLOBALDEF (int, color, 0);
+ GLOBALVALUEDEF (int, RED, 0);
+ GLOBALVALUEDEF (int, BLUE, 1);
+ GLOBALVALUEDEF (int, GREEN, 3);
+ #else
+ enum globaldef color {RED, BLUE, GREEN = 3};
+ #endif
+
+\1f
+File: gcc.info, Node: VMS Misc, Prev: Global Declarations, Up: VMS
+
+14.3 Other VMS Issues
+=====================
+
+GCC automatically arranges for `main' to return 1 by default if you
+fail to specify an explicit return value. This will be interpreted by
+VMS as a status code indicating a normal successful completion.
+Version 1 of GCC did not provide this default.
+
+ GCC on VMS works only with the GNU assembler, GAS. You need version
+1.37 or later of GAS in order to produce value debugging information for
+the VMS debugger. Use the ordinary VMS linker with the object files
+produced by GAS.
+
+ Under previous versions of GCC, the generated code would occasionally
+give strange results when linked to the sharable `VAXCRTL' library.
+Now this should work.
+
+ A caveat for use of `const' global variables: the `const' modifier
+must be specified in every external declaration of the variable in all
+of the source files that use that variable. Otherwise the linker will
+issue warnings about conflicting attributes for the variable. Your
+program will still work despite the warnings, but the variable will be
+placed in writable storage.
+
+ Although the VMS linker does distinguish between upper and lower case
+letters in global symbols, most VMS compilers convert all such symbols
+into upper case and most run-time library routines also have upper case
+names. To be able to reliably call such routines, GCC (by means of the
+assembler GAS) converts global symbols into upper case like other VMS
+compilers. However, since the usual practice in C is to distinguish
+case, GCC (via GAS) tries to preserve usual C behavior by augmenting
+each name that is not all lower case. This means truncating the name
+to at most 23 characters and then adding more characters at the end
+which encode the case pattern of those 23. Names which contain at
+least one dollar sign are an exception; they are converted directly into
+upper case without augmentation.
+
+ Name augmentation yields bad results for programs that use
+precompiled libraries (such as Xlib) which were generated by another
+compiler. You can use the compiler option `/NOCASE_HACK' to inhibit
+augmentation; it makes external C functions and variables
+case-independent as is usual on VMS. Alternatively, you could write
+all references to the functions and variables in such libraries using
+lower case; this will work on VMS, but is not portable to other
+systems. The compiler option `/NAMES' also provides control over
+global name handling.
+
+ Function and variable names are handled somewhat differently with
+G++. The GNU C++ compiler performs "name mangling" on function names,
+which means that it adds information to the function name to describe
+the data types of the arguments that the function takes. One result of
+this is that the name of a function can become very long. Since the
+VMS linker only recognizes the first 31 characters in a name, special
+action is taken to ensure that each function and variable has a unique
+name that can be represented in 31 characters.
+
+ If the name (plus a name augmentation, if required) is less than 32
+characters in length, then no special action is performed. If the name
+is longer than 31 characters, the assembler (GAS) will generate a hash
+string based upon the function name, truncate the function name to 23
+characters, and append the hash string to the truncated name. If the
+`/VERBOSE' compiler option is used, the assembler will print both the
+full and truncated names of each symbol that is truncated.
+
+ The `/NOCASE_HACK' compiler option should not be used when you are
+compiling programs that use libg++. libg++ has several instances of
+objects (i.e. `Filebuf' and `filebuf') which become indistinguishable
+in a case-insensitive environment. This leads to cases where you need
+to inhibit augmentation selectively (if you were using libg++ and Xlib
+in the same program, for example). There is no special feature for
+doing this, but you can get the result by defining a macro for each
+mixed case symbol for which you wish to inhibit augmentation. The
+macro should expand into the lower case equivalent of itself. For
+example:
+
+ #define StuDlyCapS studlycaps
+
+ These macro definitions can be placed in a header file to minimize
+the number of changes to your source code.
+
+\1f
+File: gcc.info, Node: Funding, Next: GNU Project, Prev: VMS, Up: Top
+
+Funding Free Software
+*********************
+
+If you want to have more free software a few years from now, it makes
+sense for you to help encourage people to contribute funds for its
+development. The most effective approach known is to encourage
+commercial redistributors to donate.
+
+ Users of free software systems can boost the pace of development by
+encouraging for-a-fee distributors to donate part of their selling price
+to free software developers--the Free Software Foundation, and others.
+
+ The way to convince distributors to do this is to demand it and
+expect it from them. So when you compare distributors, judge them
+partly by how much they give to free software development. Show
+distributors they must compete to be the one who gives the most.
+
+ To make this approach work, you must insist on numbers that you can
+compare, such as, "We will donate ten dollars to the Frobnitz project
+for each disk sold." Don't be satisfied with a vague promise, such as
+"A portion of the profits are donated," since it doesn't give a basis
+for comparison.
+
+ Even a precise fraction "of the profits from this disk" is not very
+meaningful, since creative accounting and unrelated business decisions
+can greatly alter what fraction of the sales price counts as profit.
+If the price you pay is $50, ten percent of the profit is probably less
+than a dollar; it might be a few cents, or nothing at all.
+
+ Some redistributors do development work themselves. This is useful
+too; but to keep everyone honest, you need to inquire how much they do,
+and what kind. Some kinds of development make much more long-term
+difference than others. For example, maintaining a separate version of
+a program contributes very little; maintaining the standard version of a
+program for the whole community contributes much. Easy new ports
+contribute little, since someone else would surely do them; difficult
+ports such as adding a new CPU to the GNU Compiler Collection
+contribute more; major new features or packages contribute the most.
+
+ By establishing the idea that supporting further development is "the
+proper thing to do" when distributing free software for a fee, we can
+assure a steady flow of resources into making more free software.
+
+ Copyright (C) 1994 Free Software Foundation, Inc.
+ Verbatim copying and redistribution of this section is permitted
+ without royalty; alteration is not permitted.
+
+\1f
+File: gcc.info, Node: GNU Project, Next: Copying, Prev: Funding, Up: Top
+
+The GNU Project and GNU/Linux
+*****************************
+
+The GNU Project was launched in 1984 to develop a complete Unix-like
+operating system which is free software: the GNU system. (GNU is a
+recursive acronym for "GNU's Not Unix"; it is pronounced "guh-NEW".)
+Variants of the GNU operating system, which use the kernel Linux, are
+now widely used; though these systems are often referred to as "Linux",
+they are more accurately called GNU/Linux systems.
+
+ For more information, see:
+ `http://www.gnu.org/'
+ `http://www.gnu.org/gnu/linux-and-gnu.html'
+
+\1f
+File: gcc.info, Node: Copying, Next: GNU Free Documentation License, Prev: GNU Project, Up: Top
+
+GNU GENERAL PUBLIC LICENSE
+**************************
+
+ Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+ 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+Preamble
+========
+
+The licenses for most software are designed to take away your freedom
+to share and change it. By contrast, the GNU General Public License is
+intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users. This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it. (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.) You can apply it to
+your programs, too.
+
+ When we speak of free software, we are referring to freedom, not
+price. Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it in
+new free programs; and that you know you can do these things.
+
+ To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+ For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have. You must make sure that they, too, receive or can get the
+source code. And you must show them these terms so they know their
+rights.
+
+ We protect your rights with two steps: (1) copyright the software,
+and (2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+ Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software. If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+ Finally, any free program is threatened constantly by software
+patents. We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary. To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+ The precise terms and conditions for copying, distribution and
+modification follow.
+
+ TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+ 0. This License applies to any program or other work which contains a
+ notice placed by the copyright holder saying it may be distributed
+ under the terms of this General Public License. The "Program",
+ below, refers to any such program or work, and a "work based on
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+ portion of it, either verbatim or with modifications and/or
+ translated into another language. (Hereinafter, translation is
+ included without limitation in the term "modification".) Each
+ licensee is addressed as "you".
+
+ Activities other than copying, distribution and modification are
+ not covered by this License; they are outside its scope. The act
+ of running the Program is not restricted, and the output from the
+ Program is covered only if its contents constitute a work based on
+ the Program (independent of having been made by running the
+ Program). Whether that is true depends on what the Program does.
+
+ 1. You may copy and distribute verbatim copies of the Program's
+ source code as you receive it, in any medium, provided that you
+ conspicuously and appropriately publish on each copy an appropriate
+ copyright notice and disclaimer of warranty; keep intact all the
+ notices that refer to this License and to the absence of any
+ warranty; and give any other recipients of the Program a copy of
+ this License along with the Program.
+
+ You may charge a fee for the physical act of transferring a copy,
+ and you may at your option offer warranty protection in exchange
+ for a fee.
+
+ 2. You may modify your copy or copies of the Program or any portion
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+ above, provided that you also meet all of these conditions:
+
+ a. You must cause the modified files to carry prominent notices
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+
+ b. You must cause any work that you distribute or publish, that
+ in whole or in part contains or is derived from the Program
+ or any part thereof, to be licensed as a whole at no charge
+ to all third parties under the terms of this License.
+
+ c. If the modified program normally reads commands interactively
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+ interactive use in the most ordinary way, to print or display
+ an announcement including an appropriate copyright notice and
+ a notice that there is no warranty (or else, saying that you
+ provide a warranty) and that users may redistribute the
+ program under these conditions, and telling the user how to
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+ announcement, your work based on the Program is not required
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+
+ These requirements apply to the modified work as a whole. If
+ identifiable sections of that work are not derived from the
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+ apply to those sections when you distribute them as separate
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+ whole which is a work based on the Program, the distribution of
+ the whole must be on the terms of this License, whose permissions
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+ and every part regardless of who wrote it.
+
+ Thus, it is not the intent of this section to claim rights or
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+
+ In addition, mere aggregation of another work not based on the
+ Program with the Program (or with a work based on the Program) on
+ a volume of a storage or distribution medium does not bring the
+ other work under the scope of this License.
+
+ 3. You may copy and distribute the Program (or a work based on it,
+ under Section 2) in object code or executable form under the terms
+ of Sections 1 and 2 above provided that you also do one of the
+ following:
+
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+
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+
+ c. Accompany it with the information you received as to the offer
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+
+ The source code for a work means the preferred form of the work for
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+
+ If distribution of executable or object code is made by offering
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+ distribution of the source code, even though third parties are not
+ compelled to copy the source along with the object code.
+
+ 4. You may not copy, modify, sublicense, or distribute the Program
+ except as expressly provided under this License. Any attempt
+ otherwise to copy, modify, sublicense or distribute the Program is
+ void, and will automatically terminate your rights under this
+ License. However, parties who have received copies, or rights,
+ from you under this License will not have their licenses
+ terminated so long as such parties remain in full compliance.
+
+ 5. You are not required to accept this License, since you have not
+ signed it. However, nothing else grants you permission to modify
+ or distribute the Program or its derivative works. These actions
+ are prohibited by law if you do not accept this License.
+ Therefore, by modifying or distributing the Program (or any work
+ based on the Program), you indicate your acceptance of this
+ License to do so, and all its terms and conditions for copying,
+ distributing or modifying the Program or works based on it.
+
+ 6. Each time you redistribute the Program (or any work based on the
+ Program), the recipient automatically receives a license from the
+ original licensor to copy, distribute or modify the Program
+ subject to these terms and conditions. You may not impose any
+ further restrictions on the recipients' exercise of the rights
+ granted herein. You are not responsible for enforcing compliance
+ by third parties to this License.
+
+ 7. If, as a consequence of a court judgment or allegation of patent
+ infringement or for any other reason (not limited to patent
+ issues), conditions are imposed on you (whether by court order,
+ agreement or otherwise) that contradict the conditions of this
+ License, they do not excuse you from the conditions of this
+ License. If you cannot distribute so as to satisfy simultaneously
+ your obligations under this License and any other pertinent
+ obligations, then as a consequence you may not distribute the
+ Program at all. For example, if a patent license would not permit
+ royalty-free redistribution of the Program by all those who
+ receive copies directly or indirectly through you, then the only
+ way you could satisfy both it and this License would be to refrain
+ entirely from distribution of the Program.
+
+ If any portion of this section is held invalid or unenforceable
+ under any particular circumstance, the balance of the section is
+ intended to apply and the section as a whole is intended to apply
+ in other circumstances.
+
+ It is not the purpose of this section to induce you to infringe any
+ patents or other property right claims or to contest validity of
+ any such claims; this section has the sole purpose of protecting
+ the integrity of the free software distribution system, which is
+ implemented by public license practices. Many people have made
+ generous contributions to the wide range of software distributed
+ through that system in reliance on consistent application of that
+ system; it is up to the author/donor to decide if he or she is
+ willing to distribute software through any other system and a
+ licensee cannot impose that choice.
+
+ This section is intended to make thoroughly clear what is believed
+ to be a consequence of the rest of this License.
+
+ 8. If the distribution and/or use of the Program is restricted in
+ certain countries either by patents or by copyrighted interfaces,
+ the original copyright holder who places the Program under this
+ License may add an explicit geographical distribution limitation
+ excluding those countries, so that distribution is permitted only
+ in or among countries not thus excluded. In such case, this
+ License incorporates the limitation as if written in the body of
+ this License.
+
+ 9. The Free Software Foundation may publish revised and/or new
+ versions of the General Public License from time to time. Such
+ new versions will be similar in spirit to the present version, but
+ may differ in detail to address new problems or concerns.
+
+ Each version is given a distinguishing version number. If the
+ Program specifies a version number of this License which applies
+ to it and "any later version", you have the option of following
+ the terms and conditions either of that version or of any later
+ version published by the Free Software Foundation. If the Program
+ does not specify a version number of this License, you may choose
+ any version ever published by the Free Software Foundation.
+
+ 10. If you wish to incorporate parts of the Program into other free
+ programs whose distribution conditions are different, write to the
+ author to ask for permission. For software which is copyrighted
+ by the Free Software Foundation, write to the Free Software
+ Foundation; we sometimes make exceptions for this. Our decision
+ will be guided by the two goals of preserving the free status of
+ all derivatives of our free software and of promoting the sharing
+ and reuse of software generally.
+
+ NO WARRANTY
+ 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
+ WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
+ LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+ HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT
+ WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT
+ NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE
+ QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
+ PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
+ SERVICING, REPAIR OR CORRECTION.
+
+ 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
+ WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
+ MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
+ LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
+ INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
+ INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+ DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
+ OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY
+ OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
+ ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+
+ END OF TERMS AND CONDITIONS
+How to Apply These Terms to Your New Programs
+=============================================
+
+If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these
+terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+ ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
+ Copyright (C) YEAR NAME OF AUTHOR
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA.
+
+ Also add information on how to contact you by electronic and paper
+mail.
+
+ If the program is interactive, make it output a short notice like
+this when it starts in an interactive mode:
+
+ Gnomovision version 69, Copyright (C) YEAR NAME OF AUTHOR
+ Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
+ type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+ The hypothetical commands `show w' and `show c' should show the
+appropriate parts of the General Public License. Of course, the
+commands you use may be called something other than `show w' and `show
+c'; they could even be mouse-clicks or menu items--whatever suits your
+program.
+
+ You should also get your employer (if you work as a programmer) or
+your school, if any, to sign a "copyright disclaimer" for the program,
+if necessary. Here is a sample; alter the names:
+
+ Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+ `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+ SIGNATURE OF TY COON, 1 April 1989
+ Ty Coon, President of Vice
+
+ This General Public License does not permit incorporating your
+program into proprietary programs. If your program is a subroutine
+library, you may consider it more useful to permit linking proprietary
+applications with the library. If this is what you want to do, use the
+GNU Library General Public License instead of this License.
+
+\1f
+File: gcc.info, Node: GNU Free Documentation License, Next: Contributors, Prev: Copying, Up: Top
+
+GNU Free Documentation License
+******************************
+
+ Version 1.1, March 2000
+
+ Copyright (C) 2000 Free Software Foundation, Inc.
+ 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
+
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+ 0. PREAMBLE
+
+ The purpose of this License is to make a manual, textbook, or other
+ written document "free" in the sense of freedom: to assure everyone
+ the effective freedom to copy and redistribute it, with or without
+ modifying it, either commercially or noncommercially. Secondarily,
+ this License preserves for the author and publisher a way to get
+ credit for their work, while not being considered responsible for
+ modifications made by others.
+
+ This License is a kind of "copyleft", which means that derivative
+ works of the document must themselves be free in the same sense.
+ It complements the GNU General Public License, which is a copyleft
+ license designed for free software.
+
+ We have designed this License in order to use it for manuals for
+ free software, because free software needs free documentation: a
+ free program should come with manuals providing the same freedoms
+ that the software does. But this License is not limited to
+ software manuals; it can be used for any textual work, regardless
+ of subject matter or whether it is published as a printed book.
+ We recommend this License principally for works whose purpose is
+ instruction or reference.
+
+ 1. APPLICABILITY AND DEFINITIONS
+
+ This License applies to any manual or other work that contains a
+ notice placed by the copyright holder saying it can be distributed
+ under the terms of this License. The "Document", below, refers to
+ any such manual or work. Any member of the public is a licensee,
+ and is addressed as "you".
+
+ A "Modified Version" of the Document means any work containing the
+ Document or a portion of it, either copied verbatim, or with
+ modifications and/or translated into another language.
+
+ A "Secondary Section" is a named appendix or a front-matter
+ section of the Document that deals exclusively with the
+ relationship of the publishers or authors of the Document to the
+ Document's overall subject (or to related matters) and contains
+ nothing that could fall directly within that overall subject.
+ (For example, if the Document is in part a textbook of
+ mathematics, a Secondary Section may not explain any mathematics.)
+ The relationship could be a matter of historical connection with
+ the subject or with related matters, or of legal, commercial,
+ philosophical, ethical or political position regarding them.
+
+ The "Invariant Sections" are certain Secondary Sections whose
+ titles are designated, as being those of Invariant Sections, in
+ the notice that says that the Document is released under this
+ License.
+
+ The "Cover Texts" are certain short passages of text that are
+ listed, as Front-Cover Texts or Back-Cover Texts, in the notice
+ that says that the Document is released under this License.
+
+ A "Transparent" copy of the Document means a machine-readable copy,
+ represented in a format whose specification is available to the
+ general public, whose contents can be viewed and edited directly
+ and straightforwardly with generic text editors or (for images
+ composed of pixels) generic paint programs or (for drawings) some
+ widely available drawing editor, and that is suitable for input to
+ text formatters or for automatic translation to a variety of
+ formats suitable for input to text formatters. A copy made in an
+ otherwise Transparent file format whose markup has been designed
+ to thwart or discourage subsequent modification by readers is not
+ Transparent. A copy that is not "Transparent" is called "Opaque".
+
+ Examples of suitable formats for Transparent copies include plain
+ ASCII without markup, Texinfo input format, LaTeX input format,
+ SGML or XML using a publicly available DTD, and
+ standard-conforming simple HTML designed for human modification.
+ Opaque formats include PostScript, PDF, proprietary formats that
+ can be read and edited only by proprietary word processors, SGML
+ or XML for which the DTD and/or processing tools are not generally
+ available, and the machine-generated HTML produced by some word
+ processors for output purposes only.
+
+ The "Title Page" means, for a printed book, the title page itself,
+ plus such following pages as are needed to hold, legibly, the
+ material this License requires to appear in the title page. For
+ works in formats which do not have any title page as such, "Title
+ Page" means the text near the most prominent appearance of the
+ work's title, preceding the beginning of the body of the text.
+
+ 2. VERBATIM COPYING
+
+ You may copy and distribute the Document in any medium, either
+ commercially or noncommercially, provided that this License, the
+ copyright notices, and the license notice saying this License
+ applies to the Document are reproduced in all copies, and that you
+ add no other conditions whatsoever to those of this License. You
+ may not use technical measures to obstruct or control the reading
+ or further copying of the copies you make or distribute. However,
+ you may accept compensation in exchange for copies. If you
+ distribute a large enough number of copies you must also follow
+ the conditions in section 3.
+
+ You may also lend copies, under the same conditions stated above,
+ and you may publicly display copies.
+
+ 3. COPYING IN QUANTITY
+
+ If you publish printed copies of the Document numbering more than
+ 100, and the Document's license notice requires Cover Texts, you
+ must enclose the copies in covers that carry, clearly and legibly,
+ all these Cover Texts: Front-Cover Texts on the front cover, and
+ Back-Cover Texts on the back cover. Both covers must also clearly
+ and legibly identify you as the publisher of these copies. The
+ front cover must present the full title with all words of the
+ title equally prominent and visible. You may add other material
+ on the covers in addition. Copying with changes limited to the
+ covers, as long as they preserve the title of the Document and
+ satisfy these conditions, can be treated as verbatim copying in
+ other respects.
+
+ If the required texts for either cover are too voluminous to fit
+ legibly, you should put the first ones listed (as many as fit
+ reasonably) on the actual cover, and continue the rest onto
+ adjacent pages.
+
+ If you publish or distribute Opaque copies of the Document
+ numbering more than 100, you must either include a
+ machine-readable Transparent copy along with each Opaque copy, or
+ state in or with each Opaque copy a publicly-accessible
+ computer-network location containing a complete Transparent copy
+ of the Document, free of added material, which the general
+ network-using public has access to download anonymously at no
+ charge using public-standard network protocols. If you use the
+ latter option, you must take reasonably prudent steps, when you
+ begin distribution of Opaque copies in quantity, to ensure that
+ this Transparent copy will remain thus accessible at the stated
+ location until at least one year after the last time you
+ distribute an Opaque copy (directly or through your agents or
+ retailers) of that edition to the public.
+
+ It is requested, but not required, that you contact the authors of
+ the Document well before redistributing any large number of
+ copies, to give them a chance to provide you with an updated
+ version of the Document.
+
+ 4. MODIFICATIONS
+
+ You may copy and distribute a Modified Version of the Document
+ under the conditions of sections 2 and 3 above, provided that you
+ release the Modified Version under precisely this License, with
+ the Modified Version filling the role of the Document, thus
+ licensing distribution and modification of the Modified Version to
+ whoever possesses a copy of it. In addition, you must do these
+ things in the Modified Version:
+
+ A. Use in the Title Page (and on the covers, if any) a title
+ distinct from that of the Document, and from those of
+ previous versions (which should, if there were any, be listed
+ in the History section of the Document). You may use the
+ same title as a previous version if the original publisher of
+ that version gives permission.
+
+ B. List on the Title Page, as authors, one or more persons or
+ entities responsible for authorship of the modifications in
+ the Modified Version, together with at least five of the
+ principal authors of the Document (all of its principal
+ authors, if it has less than five).
+
+ C. State on the Title page the name of the publisher of the
+ Modified Version, as the publisher.
+
+ D. Preserve all the copyright notices of the Document.
+
+ E. Add an appropriate copyright notice for your modifications
+ adjacent to the other copyright notices.
+
+ F. Include, immediately after the copyright notices, a license
+ notice giving the public permission to use the Modified
+ Version under the terms of this License, in the form shown in
+ the Addendum below.
+
+ G. Preserve in that license notice the full lists of Invariant
+ Sections and required Cover Texts given in the Document's
+ license notice.
+
+ H. Include an unaltered copy of this License.
+
+ I. Preserve the section entitled "History", and its title, and
+ add to it an item stating at least the title, year, new
+ authors, and publisher of the Modified Version as given on
+ the Title Page. If there is no section entitled "History" in
+ the Document, create one stating the title, year, authors,
+ and publisher of the Document as given on its Title Page,
+ then add an item describing the Modified Version as stated in
+ the previous sentence.
+
+ J. Preserve the network location, if any, given in the Document
+ for public access to a Transparent copy of the Document, and
+ likewise the network locations given in the Document for
+ previous versions it was based on. These may be placed in
+ the "History" section. You may omit a network location for a
+ work that was published at least four years before the
+ Document itself, or if the original publisher of the version
+ it refers to gives permission.
+
+ K. In any section entitled "Acknowledgments" or "Dedications",
+ preserve the section's title, and preserve in the section all
+ the substance and tone of each of the contributor
+ acknowledgments and/or dedications given therein.
+
+ L. Preserve all the Invariant Sections of the Document,
+ unaltered in their text and in their titles. Section numbers
+ or the equivalent are not considered part of the section
+ titles.
+
+ M. Delete any section entitled "Endorsements". Such a section
+ may not be included in the Modified Version.
+
+ N. Do not retitle any existing section as "Endorsements" or to
+ conflict in title with any Invariant Section.
+
+ If the Modified Version includes new front-matter sections or
+ appendices that qualify as Secondary Sections and contain no
+ material copied from the Document, you may at your option
+ designate some or all of these sections as invariant. To do this,
+ add their titles to the list of Invariant Sections in the Modified
+ Version's license notice. These titles must be distinct from any
+ other section titles.
+
+ You may add a section entitled "Endorsements", provided it contains
+ nothing but endorsements of your Modified Version by various
+ parties--for example, statements of peer review or that the text
+ has been approved by an organization as the authoritative
+ definition of a standard.
+
+ You may add a passage of up to five words as a Front-Cover Text,
+ and a passage of up to 25 words as a Back-Cover Text, to the end
+ of the list of Cover Texts in the Modified Version. Only one
+ passage of Front-Cover Text and one of Back-Cover Text may be
+ added by (or through arrangements made by) any one entity. If the
+ Document already includes a cover text for the same cover,
+ previously added by you or by arrangement made by the same entity
+ you are acting on behalf of, you may not add another; but you may
+ replace the old one, on explicit permission from the previous
+ publisher that added the old one.
+
+ The author(s) and publisher(s) of the Document do not by this
+ License give permission to use their names for publicity for or to
+ assert or imply endorsement of any Modified Version.
+
+ 5. COMBINING DOCUMENTS
+
+ You may combine the Document with other documents released under
+ this License, under the terms defined in section 4 above for
+ modified versions, provided that you include in the combination
+ all of the Invariant Sections of all of the original documents,
+ unmodified, and list them all as Invariant Sections of your
+ combined work in its license notice.
+
+ The combined work need only contain one copy of this License, and
+ multiple identical Invariant Sections may be replaced with a single
+ copy. If there are multiple Invariant Sections with the same name
+ but different contents, make the title of each such section unique
+ by adding at the end of it, in parentheses, the name of the
+ original author or publisher of that section if known, or else a
+ unique number. Make the same adjustment to the section titles in
+ the list of Invariant Sections in the license notice of the
+ combined work.
+
+ In the combination, you must combine any sections entitled
+ "History" in the various original documents, forming one section
+ entitled "History"; likewise combine any sections entitled
+ "Acknowledgments", and any sections entitled "Dedications". You
+ must delete all sections entitled "Endorsements."
+
+ 6. COLLECTIONS OF DOCUMENTS
+
+ You may make a collection consisting of the Document and other
+ documents released under this License, and replace the individual
+ copies of this License in the various documents with a single copy
+ that is included in the collection, provided that you follow the
+ rules of this License for verbatim copying of each of the
+ documents in all other respects.
+
+ You may extract a single document from such a collection, and
+ distribute it individually under this License, provided you insert
+ a copy of this License into the extracted document, and follow
+ this License in all other respects regarding verbatim copying of
+ that document.
+
+ 7. AGGREGATION WITH INDEPENDENT WORKS
+
+ A compilation of the Document or its derivatives with other
+ separate and independent documents or works, in or on a volume of
+ a storage or distribution medium, does not as a whole count as a
+ Modified Version of the Document, provided no compilation
+ copyright is claimed for the compilation. Such a compilation is
+ called an "aggregate", and this License does not apply to the
+ other self-contained works thus compiled with the Document, on
+ account of their being thus compiled, if they are not themselves
+ derivative works of the Document.
+
+ If the Cover Text requirement of section 3 is applicable to these
+ copies of the Document, then if the Document is less than one
+ quarter of the entire aggregate, the Document's Cover Texts may be
+ placed on covers that surround only the Document within the
+ aggregate. Otherwise they must appear on covers around the whole
+ aggregate.
+
+ 8. TRANSLATION
+
+ Translation is considered a kind of modification, so you may
+ distribute translations of the Document under the terms of section
+ 4. Replacing Invariant Sections with translations requires special
+ permission from their copyright holders, but you may include
+ translations of some or all Invariant Sections in addition to the
+ original versions of these Invariant Sections. You may include a
+ translation of this License provided that you also include the
+ original English version of this License. In case of a
+ disagreement between the translation and the original English
+ version of this License, the original English version will prevail.
+
+ 9. TERMINATION
+
+ You may not copy, modify, sublicense, or distribute the Document
+ except as expressly provided for under this License. Any other
+ attempt to copy, modify, sublicense or distribute the Document is
+ void, and will automatically terminate your rights under this
+ License. However, parties who have received copies, or rights,
+ from you under this License will not have their licenses
+ terminated so long as such parties remain in full compliance.
+
+ 10. FUTURE REVISIONS OF THIS LICENSE
+
+ The Free Software Foundation may publish new, revised versions of
+ the GNU Free Documentation License from time to time. Such new
+ versions will be similar in spirit to the present version, but may
+ differ in detail to address new problems or concerns. See
+ `http://www.gnu.org/copyleft/'.
+
+ Each version of the License is given a distinguishing version
+ number. If the Document specifies that a particular numbered
+ version of this License "or any later version" applies to it, you
+ have the option of following the terms and conditions either of
+ that specified version or of any later version that has been
+ published (not as a draft) by the Free Software Foundation. If
+ the Document does not specify a version number of this License,
+ you may choose any version ever published (not as a draft) by the
+ Free Software Foundation.
+
+ADDENDUM: How to use this License for your documents
+====================================================
+
+To use this License in a document you have written, include a copy of
+the License in the document and put the following copyright and license
+notices just after the title page:
+
+ Copyright (C) YEAR YOUR NAME.
+ Permission is granted to copy, distribute and/or modify this document
+ under the terms of the GNU Free Documentation License, Version 1.1
+ or any later version published by the Free Software Foundation;
+ with the Invariant Sections being LIST THEIR TITLES, with the
+ Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
+ A copy of the license is included in the section entitled ``GNU
+ Free Documentation License''.
+
+ If you have no Invariant Sections, write "with no Invariant Sections"
+instead of saying which ones are invariant. If you have no Front-Cover
+Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being
+LIST"; likewise for Back-Cover Texts.
+
+ If your document contains nontrivial examples of program code, we
+recommend releasing these examples in parallel under your choice of
+free software license, such as the GNU General Public License, to
+permit their use in free software.
-This is doc/gcc.info, produced by makeinfo version 4.5 from
+This is doc/gcc.info, produced by makeinfo version 4.11 from
doc/gcc.texi.
INFO-DIR-SECTION Programming
funds for GNU development.
\1f
-File: gcc.info, Node: Debugging Options, Next: Optimize Options, Prev: Warning Options, Up: Invoking GCC
-
-Options for Debugging Your Program or GCC
-=========================================
-
- GCC has various special options that are used for debugging either
-your program or GCC:
-
-`-g'
- Produce debugging information in the operating system's native
- format (stabs, COFF, XCOFF, or DWARF). GDB can work with this
- debugging information.
-
- On most systems that use stabs format, `-g' enables use of extra
- debugging information that only GDB can use; this extra information
- makes debugging work better in GDB but will probably make other
- debuggers crash or refuse to read the program. If you want to
- control for certain whether to generate the extra information, use
- `-gstabs+', `-gstabs', `-gxcoff+', `-gxcoff', `-gdwarf-1+',
- `-gdwarf-1', or `-gvms' (see below).
-
- Unlike most other C compilers, GCC allows you to use `-g' with
- `-O'. The shortcuts taken by optimized code may occasionally
- produce surprising results: some variables you declared may not
- exist at all; flow of control may briefly move where you did not
- expect it; some statements may not be executed because they
- compute constant results or their values were already at hand;
- some statements may execute in different places because they were
- moved out of loops.
-
- Nevertheless it proves possible to debug optimized output. This
- makes it reasonable to use the optimizer for programs that might
- have bugs.
-
- The following options are useful when GCC is generated with the
- capability for more than one debugging format.
-
-`-ggdb'
- Produce debugging information for use by GDB. This means to use
- the most expressive format available (DWARF 2, stabs, or the
- native format if neither of those are supported), including GDB
- extensions if at all possible.
-
-`-gstabs'
- Produce debugging information in stabs format (if that is
- supported), without GDB extensions. This is the format used by
- DBX on most BSD systems. On MIPS, Alpha and System V Release 4
- systems this option produces stabs debugging output which is not
- understood by DBX or SDB. On System V Release 4 systems this
- option requires the GNU assembler.
-
-`-gstabs+'
- Produce debugging information in stabs format (if that is
- supported), using GNU extensions understood only by the GNU
- debugger (GDB). The use of these extensions is likely to make
- other debuggers crash or refuse to read the program.
-
-`-gcoff'
- Produce debugging information in COFF format (if that is
- supported). This is the format used by SDB on most System V
- systems prior to System V Release 4.
-
-`-gxcoff'
- Produce debugging information in XCOFF format (if that is
- supported). This is the format used by the DBX debugger on IBM
- RS/6000 systems.
-
-`-gxcoff+'
- Produce debugging information in XCOFF format (if that is
- supported), using GNU extensions understood only by the GNU
- debugger (GDB). The use of these extensions is likely to make
- other debuggers crash or refuse to read the program, and may cause
- assemblers other than the GNU assembler (GAS) to fail with an
- error.
-
-`-gdwarf'
- Produce debugging information in DWARF version 1 format (if that is
- supported). This is the format used by SDB on most System V
- Release 4 systems.
-
-`-gdwarf+'
- Produce debugging information in DWARF version 1 format (if that is
- supported), using GNU extensions understood only by the GNU
- debugger (GDB). The use of these extensions is likely to make
- other debuggers crash or refuse to read the program.
-
-`-gdwarf-2'
- Produce debugging information in DWARF version 2 format (if that is
- supported). This is the format used by DBX on IRIX 6.
-
-`-gvms'
- Produce debugging information in VMS debug format (if that is
- supported). This is the format used by DEBUG on VMS systems.
-
-`-gLEVEL'
-`-ggdbLEVEL'
-`-gstabsLEVEL'
-`-gcoffLEVEL'
-`-gxcoffLEVEL'
-`-gvmsLEVEL'
- Request debugging information and also use LEVEL to specify how
- much information. The default level is 2.
-
- Level 1 produces minimal information, enough for making backtraces
- in parts of the program that you don't plan to debug. This
- includes descriptions of functions and external variables, but no
- information about local variables and no line numbers.
-
- Level 3 includes extra information, such as all the macro
- definitions present in the program. Some debuggers support macro
- expansion when you use `-g3'.
-
- Note that in order to avoid confusion between DWARF1 debug level 2,
- and DWARF2, neither `-gdwarf' nor `-gdwarf-2' accept a
- concatenated debug level. Instead use an additional `-gLEVEL'
- option to change the debug level for DWARF1 or DWARF2.
-
-`-p'
- Generate extra code to write profile information suitable for the
- analysis program `prof'. You must use this option when compiling
- the source files you want data about, and you must also use it when
- linking.
-
-`-pg'
- Generate extra code to write profile information suitable for the
- analysis program `gprof'. You must use this option when compiling
- the source files you want data about, and you must also use it when
- linking.
-
-`-Q'
- Makes the compiler print out each function name as it is compiled,
- and print some statistics about each pass when it finishes.
-
-`-ftime-report'
- Makes the compiler print some statistics about the time consumed
- by each pass when it finishes.
-
-`-fmem-report'
- Makes the compiler print some statistics about permanent memory
- allocation when it finishes.
-
-`-fprofile-arcs'
- Instrument "arcs" during compilation to generate coverage data or
- for profile-directed block ordering. During execution the program
- records how many times each branch is executed and how many times
- it is taken. When the compiled program exits it saves this data
- to a file called `SOURCENAME.da' for each source file.
-
- For profile-directed block ordering, compile the program with
- `-fprofile-arcs' plus optimization and code generation options,
- generate the arc profile information by running the program on a
- selected workload, and then compile the program again with the same
- optimization and code generation options plus
- `-fbranch-probabilities' (*note Options that Control Optimization:
- Optimize Options.).
-
- The other use of `-fprofile-arcs' is for use with `gcov', when it
- is used with the `-ftest-coverage' option.
-
- With `-fprofile-arcs', for each function of your program GCC
- creates a program flow graph, then finds a spanning tree for the
- graph. Only arcs that are not on the spanning tree have to be
- instrumented: the compiler adds code to count the number of times
- that these arcs are executed. When an arc is the only exit or
- only entrance to a block, the instrumentation code can be added to
- the block; otherwise, a new basic block must be created to hold
- the instrumentation code.
-
-`-ftest-coverage'
- Create data files for the `gcov' code-coverage utility (*note
- `gcov'--a Test Coverage Program: Gcov.). The data file names
- begin with the name of your source file:
-
- `SOURCENAME.bb'
- A mapping from basic blocks to line numbers, which `gcov'
- uses to associate basic block execution counts with line
- numbers.
-
- `SOURCENAME.bbg'
- A list of all arcs in the program flow graph. This allows
- `gcov' to reconstruct the program flow graph, so that it can
- compute all basic block and arc execution counts from the
- information in the `SOURCENAME.da' file.
-
- Use `-ftest-coverage' with `-fprofile-arcs'; the latter option
- adds instrumentation to the program, which then writes execution
- counts to another data file:
-
- `SOURCENAME.da'
- Runtime arc execution counts, used in conjunction with the arc
- information in the file `SOURCENAME.bbg'.
-
- Coverage data will map better to the source files if
- `-ftest-coverage' is used without optimization.
-
-`-dLETTERS'
- Says to make debugging dumps during compilation at times specified
- by LETTERS. This is used for debugging the compiler. The file
- names for most of the dumps are made by appending a pass number
- and a word to the source file name (e.g. `foo.c.00.rtl' or
- `foo.c.01.sibling'). Here are the possible letters for use in
- LETTERS, and their meanings:
+File: gcc.info, Node: Contributors, Next: Option Index, Prev: GNU Free Documentation License, Up: Top
- `A'
- Annotate the assembler output with miscellaneous debugging
- information.
+Contributors to GCC
+*******************
- `b'
- Dump after computing branch probabilities, to `FILE.14.bp'.
+The GCC project would like to thank its many contributors. Without
+them the project would not have been nearly as successful as it has
+been. Any omissions in this list are accidental. Feel free to contact
+<law@redhat.com> if you have been left out or some of your
+contributions are not listed. Please keep this list in alphabetical
+order.
- `B'
- Dump after block reordering, to `FILE.29.bbro'.
+ * Analog Devices helped implement the support for complex data types
+ and iterators.
- `c'
- Dump after instruction combination, to the file
- `FILE.16.combine'.
+ * John David Anglin for threading-related fixes and improvements to
+ libstdc++-v3, and the HP-UX port.
- `C'
- Dump after the first if conversion, to the file `FILE.17.ce'.
+ * James van Artsdalen wrote the code that makes efficient use of the
+ Intel 80387 register stack.
- `d'
- Dump after delayed branch scheduling, to `FILE.31.dbr'.
+ * Alasdair Baird for various bugfixes.
- `D'
- Dump all macro definitions, at the end of preprocessing, in
- addition to normal output.
+ * Gerald Baumgartner added the signature extension to the C++ front
+ end.
- `e'
- Dump after SSA optimizations, to `FILE.04.ssa' and
- `FILE.07.ussa'.
+ * Godmar Back for his Java improvements and encouragement.
- `E'
- Dump after the second if conversion, to `FILE.26.ce2'.
+ * Scott Bambrough for help porting the Java compiler.
- `f'
- Dump after life analysis, to `FILE.15.life'.
+ * Jon Beniston for his Win32 port of Java.
- `F'
- Dump after purging `ADDRESSOF' codes, to `FILE.09.addressof'.
+ * Geoff Berry for his Java object serialization work and various
+ patches.
- `g'
- Dump after global register allocation, to `FILE.21.greg'.
+ * Eric Blake for helping to make GCJ and libgcj conform to the
+ specifications.
- `h'
- Dump after finalization of EH handling code, to `FILE.02.eh'.
+ * Hans-J. Boehm for his garbage collector, IA-64 libffi port, and
+ other Java work.
- `k'
- Dump after reg-to-stack conversion, to `FILE.28.stack'.
+ * Neil Booth for work on cpplib, lang hooks, debug hooks and other
+ miscellaneous clean-ups.
- `o'
- Dump after post-reload optimizations, to `FILE.22.postreload'.
+ * Per Bothner for his direction via the steering committee and
+ various improvements to our infrastructure for supporting new
+ languages. Chill front end implementation. Initial
+ implementations of cpplib, fix-header, config.guess, libio, and
+ past C++ library (libg++) maintainer. Dreaming up, designing and
+ implementing much of GCJ.
- `G'
- Dump after GCSE, to `FILE.10.gcse'.
+ * Devon Bowen helped port GCC to the Tahoe.
- `i'
- Dump after sibling call optimizations, to `FILE.01.sibling'.
+ * Don Bowman for mips-vxworks contributions.
- `j'
- Dump after the first jump optimization, to `FILE.03.jump'.
+ * Dave Brolley for work on cpplib and Chill.
- `k'
- Dump after conversion from registers to stack, to
- `FILE.32.stack'.
+ * Robert Brown implemented the support for Encore 32000 systems.
- `l'
- Dump after local register allocation, to `FILE.20.lreg'.
+ * Christian Bruel for improvements to local store elimination.
- `L'
- Dump after loop optimization, to `FILE.11.loop'.
+ * Herman A.J. ten Brugge for various fixes.
- `M'
- Dump after performing the machine dependent reorganisation
- pass, to `FILE.30.mach'.
+ * Joerg Brunsmann for Java compiler hacking and help with the GCJ
+ FAQ.
- `n'
- Dump after register renumbering, to `FILE.25.rnreg'.
+ * Joe Buck for his direction via the steering committee.
- `N'
- Dump after the register move pass, to `FILE.18.regmove'.
+ * Craig Burley for leadership of the Fortran effort.
- `r'
- Dump after RTL generation, to `FILE.00.rtl'.
+ * Stephan Buys for contributing Doxygen notes for libstdc++.
- `R'
- Dump after the second scheduling pass, to `FILE.27.sched2'.
+ * Paolo Carlini for libstdc++ work: lots of efficiency improvements
+ to the string class, hard detective work on the frustrating
+ localization issues, and keeping up with the problem reports.
- `s'
- Dump after CSE (including the jump optimization that
- sometimes follows CSE), to `FILE.08.cse'.
+ * John Carr for his alias work, SPARC hacking, infrastructure
+ improvements, previous contributions to the steering committee,
+ loop optimizations, etc.
- `S'
- Dump after the first scheduling pass, to `FILE.19.sched'.
+ * Steve Chamberlain for support for the Hitachi SH and H8 processors
+ and the PicoJava processor, and for GCJ config fixes.
- `t'
- Dump after the second CSE pass (including the jump
- optimization that sometimes follows CSE), to `FILE.12.cse2'.
+ * Glenn Chambers for help with the GCJ FAQ.
- `w'
- Dump after the second flow pass, to `FILE.23.flow2'.
+ * John-Marc Chandonia for various libgcj patches.
- `X'
- Dump after SSA dead code elimination, to `FILE.06.ssadce'.
+ * Scott Christley for his Objective-C contributions.
- `z'
- Dump after the peephole pass, to `FILE.24.peephole2'.
+ * Eric Christopher for his Java porting help and clean-ups.
- `a'
- Produce all the dumps listed above.
+ * Branko Cibej for more warning contributions.
- `m'
- Print statistics on memory usage, at the end of the run, to
- standard error.
-
- `p'
- Annotate the assembler output with a comment indicating which
- pattern and alternative was used. The length of each
- instruction is also printed.
-
- `P'
- Dump the RTL in the assembler output as a comment before each
- instruction. Also turns on `-dp' annotation.
-
- `v'
- For each of the other indicated dump files (except for
- `FILE.00.rtl'), dump a representation of the control flow
- graph suitable for viewing with VCG to `FILE.PASS.vcg'.
-
- `x'
- Just generate RTL for a function instead of compiling it.
- Usually used with `r'.
-
- `y'
- Dump debugging information during parsing, to standard error.
-
-`-fdump-unnumbered'
- When doing debugging dumps (see `-d' option above), suppress
- instruction numbers and line number note output. This makes it
- more feasible to use diff on debugging dumps for compiler
- invocations with different options, in particular with and without
- `-g'.
-
-`-fdump-translation-unit (C and C++ only)'
-`-fdump-translation-unit-OPTIONS (C and C++ only)'
- Dump a representation of the tree structure for the entire
- translation unit to a file. The file name is made by appending
- `.tu' to the source file name. If the `-OPTIONS' form is used,
- OPTIONS controls the details of the dump as described for the
- `-fdump-tree' options.
-
-`-fdump-class-hierarchy (C++ only)'
-`-fdump-class-hierarchy-OPTIONS (C++ only)'
- Dump a representation of each class's hierarchy and virtual
- function table layout to a file. The file name is made by
- appending `.class' to the source file name. If the `-OPTIONS'
- form is used, OPTIONS controls the details of the dump as
- described for the `-fdump-tree' options.
-
-`-fdump-tree-SWITCH (C++ only)'
-`-fdump-tree-SWITCH-OPTIONS (C++ only)'
- Control the dumping at various stages of processing the
- intermediate language tree to a file. The file name is generated
- by appending a switch specific suffix to the source file name. If
- the `-OPTIONS' form is used, OPTIONS is a list of `-' separated
- options that control the details of the dump. Not all options are
- applicable to all dumps, those which are not meaningful will be
- ignored. The following options are available
-
- `address'
- Print the address of each node. Usually this is not
- meaningful as it changes according to the environment and
- source file. Its primary use is for tying up a dump file with
- a debug environment.
-
- `slim'
- Inhibit dumping of members of a scope or body of a function
- merely because that scope has been reached. Only dump such
- items when they are directly reachable by some other path.
-
- `all'
- Turn on all options.
-
- The following tree dumps are possible:
- `original'
- Dump before any tree based optimization, to `FILE.original'.
-
- `optimized'
- Dump after all tree based optimization, to `FILE.optimized'.
-
- `inlined'
- Dump after function inlining, to `FILE.inlined'.
-
-`-fsched-verbose=N'
- On targets that use instruction scheduling, this option controls
- the amount of debugging output the scheduler prints. This
- information is written to standard error, unless `-dS' or `-dR' is
- specified, in which case it is output to the usual dump listing
- file, `.sched' or `.sched2' respectively. However for N greater
- than nine, the output is always printed to standard error.
-
- For N greater than zero, `-fsched-verbose' outputs the same
- information as `-dRS'. For N greater than one, it also output
- basic block probabilities, detailed ready list information and
- unit/insn info. For N greater than two, it includes RTL at abort
- point, control-flow and regions info. And for N over four,
- `-fsched-verbose' also includes dependence info.
-
-`-fpretend-float'
- When running a cross-compiler, pretend that the target machine
- uses the same floating point format as the host machine. This
- causes incorrect output of the actual floating constants, but the
- actual instruction sequence will probably be the same as GCC would
- make when running on the target machine.
-
-`-save-temps'
- Store the usual "temporary" intermediate files permanently; place
- them in the current directory and name them based on the source
- file. Thus, compiling `foo.c' with `-c -save-temps' would produce
- files `foo.i' and `foo.s', as well as `foo.o'. This creates a
- preprocessed `foo.i' output file even though the compiler now
- normally uses an integrated preprocessor.
-
-`-time'
- Report the CPU time taken by each subprocess in the compilation
- sequence. For C source files, this is the compiler proper and
- assembler (plus the linker if linking is done). The output looks
- like this:
-
- # cc1 0.12 0.01
- # as 0.00 0.01
-
- The first number on each line is the "user time," that is time
- spent executing the program itself. The second number is "system
- time," time spent executing operating system routines on behalf of
- the program. Both numbers are in seconds.
-
-`-print-file-name=LIBRARY'
- Print the full absolute name of the library file LIBRARY that
- would be used when linking--and don't do anything else. With this
- option, GCC does not compile or link anything; it just prints the
- file name.
-
-`-print-multi-directory'
- Print the directory name corresponding to the multilib selected by
- any other switches present in the command line. This directory is
- supposed to exist in `GCC_EXEC_PREFIX'.
-
-`-print-multi-lib'
- Print the mapping from multilib directory names to compiler
- switches that enable them. The directory name is separated from
- the switches by `;', and each switch starts with an `@' instead of
- the `-', without spaces between multiple switches. This is
- supposed to ease shell-processing.
-
-`-print-prog-name=PROGRAM'
- Like `-print-file-name', but searches for a program such as `cpp'.
-
-`-print-libgcc-file-name'
- Same as `-print-file-name=libgcc.a'.
-
- This is useful when you use `-nostdlib' or `-nodefaultlibs' but
- you do want to link with `libgcc.a'. You can do
-
- gcc -nostdlib FILES... `gcc -print-libgcc-file-name`
-
-`-print-search-dirs'
- Print the name of the configured installation directory and a list
- of program and library directories gcc will search--and don't do
- anything else.
-
- This is useful when gcc prints the error message `installation
- problem, cannot exec cpp0: No such file or directory'. To resolve
- this you either need to put `cpp0' and the other compiler
- components where gcc expects to find them, or you can set the
- environment variable `GCC_EXEC_PREFIX' to the directory where you
- installed them. Don't forget the trailing '/'. *Note Environment
- Variables::.
-
-`-dumpmachine'
- Print the compiler's target machine (for example,
- `i686-pc-linux-gnu')--and don't do anything else.
-
-`-dumpversion'
- Print the compiler version (for example, `3.0')--and don't do
- anything else.
-
-`-dumpspecs'
- Print the compiler's built-in specs--and don't do anything else.
- (This is used when GCC itself is being built.) *Note Spec Files::.
+ * The GNU Classpath project for all of their merged runtime code.
+
+ * Nick Clifton for arm, mcore, fr30, v850, m32r work, `--help', and
+ other random hacking.
+
+ * Michael Cook for libstdc++ cleanup patches to reduce warnings.
+
+ * Ralf Corsepius for SH testing and minor bugfixing.
+
+ * Stan Cox for care and feeding of the x86 port and lots of behind
+ the scenes hacking.
+
+ * Alex Crain provided changes for the 3b1.
+
+ * Ian Dall for major improvements to the NS32k port.
+
+ * Dario Dariol contributed the four varieties of sample programs
+ that print a copy of their source.
+
+ * Russell Davidson for fstream and stringstream fixes in libstdc++.
+
+ * Mo DeJong for GCJ and libgcj bug fixes.
+
+ * Gabriel Dos Reis for contributions to g++, contributions and
+ maintenance of GCC diagnostics infrastructure, libstdc++-v3,
+ including valarray<>, complex<>, maintaining the numerics library
+ (including that pesky <limits> :-) and keeping up-to-date anything
+ to do with numbers.
+
+ * Ulrich Drepper for his work on glibc, testing of GCC using glibc,
+ ISO C99 support, CFG dumping support, etc., plus support of the
+ C++ runtime libraries including for all kinds of C interface
+ issues, contributing and maintaining complex<>, sanity checking
+ and disbursement, configuration architecture, libio maintenance,
+ and early math work.
+
+ * Richard Earnshaw for his ongoing work with the ARM.
+
+ * David Edelsohn for his direction via the steering committee,
+ ongoing work with the RS6000/PowerPC port, help cleaning up Haifa
+ loop changes, and for doing the entire AIX port of libstdc++ with
+ his bare hands.
+
+ * Kevin Ediger for the floating point formatting of num_put::do_put
+ in libstdc++.
+
+ * Phil Edwards for libstdc++ work including configuration hackery,
+ documentation maintainer, chief breaker of the web pages, the
+ occasional iostream bugfix, and work on shared library symbol
+ versioning.
+
+ * Paul Eggert for random hacking all over GCC.
+
+ * Mark Elbrecht for various DJGPP improvements, and for libstdc++
+ configuration support for locales and fstream-related fixes.
+
+ * Vadim Egorov for libstdc++ fixes in strings, streambufs, and
+ iostreams.
+
+ * Ben Elliston for his work to move the Objective-C runtime into its
+ own subdirectory and for his work on autoconf.
+
+ * Marc Espie for OpenBSD support.
+
+ * Doug Evans for much of the global optimization framework, arc,
+ m32r, and SPARC work.
+
+ * Fred Fish for BeOS support and Ada fixes.
+
+ * Ivan Fontes Garcia for the Portugese translation of the GCJ FAQ.
+
+ * Peter Gerwinski for various bugfixes and the Pascal front end.
+
+ * Kaveh Ghazi for his direction via the steering committee and
+ amazing work to make `-W -Wall' useful.
+
+ * John Gilmore for a donation to the FSF earmarked improving GNU
+ Java.
+
+ * Judy Goldberg for c++ contributions.
+
+ * Torbjorn Granlund for various fixes and the c-torture testsuite,
+ multiply- and divide-by-constant optimization, improved long long
+ support, improved leaf function register allocation, and his
+ direction via the steering committee.
+
+ * Anthony Green for his `-Os' contributions and Java front end work.
+
+ * Stu Grossman for gdb hacking, allowing GCJ developers to debug our
+ code.
+
+ * Michael K. Gschwind contributed the port to the PDP-11.
+
+ * Ron Guilmette implemented the `protoize' and `unprotoize' tools,
+ the support for Dwarf symbolic debugging information, and much of
+ the support for System V Release 4. He has also worked heavily on
+ the Intel 386 and 860 support.
+
+ * Bruno Haible for improvements in the runtime overhead for EH, new
+ warnings and assorted bugfixes.
+
+ * Andrew Haley for his amazing Java compiler and library efforts.
+
+ * Chris Hanson assisted in making GCC work on HP-UX for the 9000
+ series 300.
+
+ * Michael Hayes for various thankless work he's done trying to get
+ the c30/c40 ports functional. Lots of loop and unroll
+ improvements and fixes.
+
+ * Kate Hedstrom for staking the g77 folks with an initial testsuite.
+
+ * Richard Henderson for his ongoing SPARC, alpha, and ia32 work, loop
+ opts, and generally fixing lots of old problems we've ignored for
+ years, flow rewrite and lots of further stuff, including reviewing
+ tons of patches.
+
+ * Nobuyuki Hikichi of Software Research Associates, Tokyo,
+ contributed the support for the Sony NEWS machine.
+
+ * Manfred Hollstein for his ongoing work to keep the m88k alive, lots
+ of testing an bugfixing, particularly of our configury code.
+
+ * Steve Holmgren for MachTen patches.
+
+ * Jan Hubicka for his x86 port improvements.
+
+ * Christian Iseli for various bugfixes.
+
+ * Kamil Iskra for general m68k hacking.
+
+ * Lee Iverson for random fixes and MIPS testing.
+
+ * Andreas Jaeger for various fixes to the MIPS port
+
+ * Jakub Jelinek for his SPARC work and sibling call optimizations as
+ well as lots of bug fixes and test cases, and for improving the
+ Java build system.
+
+ * Janis Johnson for ia64 testing and fixes and for her quality
+ improvement sidetracks.
+
+ * J. Kean Johnston for OpenServer support.
+
+ * Tim Josling for the sample language treelang based originally on
+ Richard Kenner's ""toy" language".
+
+ * Nicolai Josuttis for additional libstdc++ documentation.
+
+ * Klaus Kaempf for his ongoing work to make alpha-vms a viable
+ target.
+
+ * David Kashtan of SRI adapted GCC to VMS.
+
+ * Ryszard Kabatek for many, many libstdc++ bugfixes and
+ optimizations of strings, especially member functions, and for
+ auto_ptr fixes.
+
+ * Geoffrey Keating for his ongoing work to make the PPC work for
+ GNU/Linux and his automatic regression tester.
+
+ * Brendan Kehoe for his ongoing work with g++ and for a lot of early
+ work in just about every part of libstdc++.
+
+ * Oliver M. Kellogg of Deutsche Aerospace contributed the port to the
+ MIL-STD-1750A.
+
+ * Richard Kenner of the New York University Ultracomputer Research
+ Laboratory wrote the machine descriptions for the AMD 29000, the
+ DEC Alpha, the IBM RT PC, and the IBM RS/6000 as well as the
+ support for instruction attributes. He also made changes to
+ better support RISC processors including changes to common
+ subexpression elimination, strength reduction, function calling
+ sequence handling, and condition code support, in addition to
+ generalizing the code for frame pointer elimination and delay slot
+ scheduling. Richard Kenner was also the head maintainer of GCC
+ for several years.
+
+ * Mumit Khan for various contributions to the Cygwin and Mingw32
+ ports and maintaining binary releases for Windows hosts, and for
+ massive libstdc++ porting work to Cygwin/Mingw32.
+
+ * Robin Kirkham for cpu32 support.
+
+ * Mark Klein for PA improvements.
+
+ * Thomas Koenig for various bugfixes.
+
+ * Bruce Korb for the new and improved fixincludes code.
+
+ * Benjamin Kosnik for his g++ work and for leading the libstdc++-v3
+ effort.
+
+ * Charles LaBrec contributed the support for the Integrated Solutions
+ 68020 system.
+
+ * Jeff Law for his direction via the steering committee,
+ coordinating the entire egcs project and GCC 2.95, rolling out
+ snapshots and releases, handling merges from GCC2, reviewing tons
+ of patches that might have fallen through the cracks else, and
+ random but extensive hacking.
+
+ * Marc Lehmann for his direction via the steering committee and
+ helping with analysis and improvements of x86 performance.
+
+ * Ted Lemon wrote parts of the RTL reader and printer.
+
+ * Kriang Lerdsuwanakij for improvements to demangler and various c++
+ fixes.
+
+ * Warren Levy for tremendous work on libgcj (Java Runtime Library)
+ and random work on the Java front end.
+
+ * Alain Lichnewsky ported GCC to the MIPS CPU.
+
+ * Oskar Liljeblad for hacking on AWT and his many Java bug reports
+ and patches.
+
+ * Robert Lipe for OpenServer support, new testsuites, testing, etc.
+
+ * Weiwen Liu for testing and various bugfixes.
+
+ * Dave Love for his ongoing work with the Fortran front end and
+ runtime libraries.
+
+ * Martin von Lo"wis for internal consistency checking infrastructure,
+ various C++ improvements including namespace support, and tons of
+ assistance with libstdc++/compiler merges.
+
+ * H.J. Lu for his previous contributions to the steering committee,
+ many x86 bug reports, prototype patches, and keeping the GNU/Linux
+ ports working.
+
+ * Greg McGary for random fixes and (someday) bounded pointers.
+
+ * Andrew MacLeod for his ongoing work in building a real EH system,
+ various code generation improvements, work on the global
+ optimizer, etc.
+
+ * Vladimir Makarov for hacking some ugly i960 problems, PowerPC
+ hacking improvements to compile-time performance, overall
+ knowledge and direction in the area of instruction scheduling, and
+ design and implementation of the automaton based instruction
+ scheduler.
+
+ * Bob Manson for his behind the scenes work on dejagnu.
+
+ * Philip Martin for lots of libstdc++ string and vector iterator
+ fixes and improvements, and string clean up and testsuites.
+
+ * All of the Mauve project contributors, for Java test code.
+
+ * Bryce McKinlay for numerous GCJ and libgcj fixes and improvements.
+
+ * Adam Megacz for his work on the Win32 port of GCJ.
+
+ * Michael Meissner for LRS framework, ia32, m32r, v850, m88k, MIPS,
+ powerpc, haifa, ECOFF debug support, and other assorted hacking.
+
+ * Jason Merrill for his direction via the steering committee and
+ leading the g++ effort.
+
+ * David Miller for his direction via the steering committee, lots of
+ SPARC work, improvements in jump.c and interfacing with the Linux
+ kernel developers.
+
+ * Gary Miller ported GCC to Charles River Data Systems machines.
+
+ * Alfred Minarik for libstdc++ string and ios bugfixes, and turning
+ the entire libstdc++ testsuite namespace-compatible.
+
+ * Mark Mitchell for his direction via the steering committee,
+ mountains of C++ work, load/store hoisting out of loops, alias
+ analysis improvements, ISO C `restrict' support, and serving as
+ release manager for GCC 3.x.
+
+ * Alan Modra for various GNU/Linux bits and testing.
+
+ * Toon Moene for his direction via the steering committee, Fortran
+ maintenance, and his ongoing work to make us make Fortran run fast.
+
+ * Jason Molenda for major help in the care and feeding of all the
+ services on the gcc.gnu.org (formerly egcs.cygnus.com)
+ machine--mail, web services, ftp services, etc etc. Doing all
+ this work on scrap paper and the backs of envelopes would have
+ been... difficult.
+
+ * Catherine Moore for fixing various ugly problems we have sent her
+ way, including the haifa bug which was killing the Alpha & PowerPC
+ Linux kernels.
+
+ * Mike Moreton for his various Java patches.
+
+ * David Mosberger-Tang for various Alpha improvements.
+
+ * Stephen Moshier contributed the floating point emulator that
+ assists in cross-compilation and permits support for floating
+ point numbers wider than 64 bits and for ISO C99 support.
+
+ * Bill Moyer for his behind the scenes work on various issues.
+
+ * Philippe De Muyter for his work on the m68k port.
+
+ * Joseph S. Myers for his work on the PDP-11 port, format checking
+ and ISO C99 support, and continuous emphasis on (and contributions
+ to) documentation.
+
+ * Nathan Myers for his work on libstdc++-v3: architecture and
+ authorship through the first three snapshots, including
+ implementation of locale infrastructure, string, shadow C headers,
+ and the initial project documentation (DESIGN, CHECKLIST, and so
+ forth). Later, more work on MT-safe string and shadow headers.
+
+ * Felix Natter for documentation on porting libstdc++.
+
+ * NeXT, Inc. donated the front end that supports the Objective-C
+ language.
+
+ * Hans-Peter Nilsson for the CRIS and MMIX ports, improvements to
+ the search engine setup, various documentation fixes and other
+ small fixes.
+
+ * Geoff Noer for this work on getting cygwin native builds working.
+
+ * David O'Brien for the FreeBSD/alpha, FreeBSD/AMD x86-64,
+ FreeBSD/ARM, FreeBSD/PowerPC, and FreeBSD/SPARC64 ports and
+ related infrastructure improvements.
+
+ * Alexandre Oliva for various build infrastructure improvements,
+ scripts and amazing testing work, including keeping libtool issues
+ sane and happy.
+
+ * Melissa O'Neill for various NeXT fixes.
+
+ * Rainer Orth for random MIPS work, including improvements to our o32
+ ABI support, improvements to dejagnu's MIPS support, Java
+ configuration clean-ups and porting work, etc.
+
+ * Paul Petersen wrote the machine description for the Alliant FX/8.
+
+ * Alexandre Petit-Bianco for implementing much of the Java compiler
+ and continued Java maintainership.
+
+ * Matthias Pfaller for major improvements to the NS32k port.
+
+ * Gerald Pfeifer for his direction via the steering committee,
+ pointing out lots of problems we need to solve, maintenance of the
+ web pages, and taking care of documentation maintenance in general.
+
+ * Ovidiu Predescu for his work on the Objective-C front end and
+ runtime libraries.
+
+ * Ken Raeburn for various improvements to checker, MIPS ports and
+ various cleanups in the compiler.
+
+ * Rolf W. Rasmussen for hacking on AWT.
+
+ * David Reese of Sun Microsystems contributed to the Solaris on
+ PowerPC port.
+
+ * Joern Rennecke for maintaining the sh port, loop, regmove & reload
+ hacking.
+
+ * Loren J. Rittle for improvements to libstdc++-v3 including the
+ FreeBSD port, threading fixes, thread-related configury changes,
+ critical threading documentation, and solutions to really tricky
+ I/O problems.
+
+ * Craig Rodrigues for processing tons of bug reports.
+
+ * Gavin Romig-Koch for lots of behind the scenes MIPS work.
+
+ * Ken Rose for fixes to our delay slot filling code.
+
+ * Paul Rubin wrote most of the preprocessor.
+
+ * Chip Salzenberg for libstdc++ patches and improvements to locales,
+ traits, Makefiles, libio, libtool hackery, and "long long" support.
+
+ * Juha Sarlin for improvements to the H8 code generator.
+
+ * Greg Satz assisted in making GCC work on HP-UX for the 9000 series
+ 300.
+
+ * Bradley Schatz for his work on the GCJ FAQ.
+
+ * Peter Schauer wrote the code to allow debugging to work on the
+ Alpha.
+
+ * William Schelter did most of the work on the Intel 80386 support.
+
+ * Bernd Schmidt for various code generation improvements and major
+ work in the reload pass as well a serving as release manager for
+ GCC 2.95.3.
+
+ * Peter Schmid for constant testing of libstdc++ - especially
+ application testing, going above and beyond what was requested for
+ the release criteria - and libstdc++ header file tweaks.
+
+ * Jason Schroeder for jcf-dump patches.
+
+ * Andreas Schwab for his work on the m68k port.
+
+ * Joel Sherrill for his direction via the steering committee, RTEMS
+ contributions and RTEMS testing.
+
+ * Nathan Sidwell for many C++ fixes/improvements.
+
+ * Jeffrey Siegal for helping RMS with the original design of GCC,
+ some code which handles the parse tree and RTL data structures,
+ constant folding and help with the original VAX & m68k ports.
+
+ * Kenny Simpson for prompting libstdc++ fixes due to defect reports
+ from the LWG (thereby keeping us in line with updates from the
+ ISO).
+
+ * Franz Sirl for his ongoing work with making the PPC port stable
+ for linux.
+
+ * Andrey Slepuhin for assorted AIX hacking.
+
+ * Christopher Smith did the port for Convex machines.
+
+ * Randy Smith finished the Sun FPA support.
+
+ * Scott Snyder for queue, iterator, istream, and string fixes and
+ libstdc++ testsuite entries.
+
+ * Brad Spencer for contributions to the GLIBCPP_FORCE_NEW technique.
+
+ * Richard Stallman, for writing the original gcc and launching the
+ GNU project.
+
+ * Jan Stein of the Chalmers Computer Society provided support for
+ Genix, as well as part of the 32000 machine description.
+
+ * Nigel Stephens for various mips16 related fixes/improvements.
+
+ * Jonathan Stone wrote the machine description for the Pyramid
+ computer.
+
+ * Graham Stott for various infrastructure improvements.
+
+ * John Stracke for his Java HTTP protocol fixes.
+
+ * Mike Stump for his Elxsi port, g++ contributions over the years
+ and more recently his vxworks contributions
+
+ * Jeff Sturm for Java porting help, bug fixes, and encouragement.
+
+ * Shigeya Suzuki for this fixes for the bsdi platforms.
+
+ * Ian Lance Taylor for his mips16 work, general configury hacking,
+ fixincludes, etc.
+
+ * Holger Teutsch provided the support for the Clipper CPU.
+
+ * Gary Thomas for his ongoing work to make the PPC work for
+ GNU/Linux.
+
+ * Philipp Thomas for random bugfixes throughout the compiler
+
+ * Jason Thorpe for thread support in libstdc++ on NetBSD.
+
+ * Kresten Krab Thorup wrote the run time support for the Objective-C
+ language and the fantastic Java bytecode interpreter.
+
+ * Michael Tiemann for random bugfixes, the first instruction
+ scheduler, initial C++ support, function integration, NS32k, SPARC
+ and M88k machine description work, delay slot scheduling.
+
+ * Andreas Tobler for his work porting libgcj to Darwin.
+
+ * Teemu Torma for thread safe exception handling support.
+
+ * Leonard Tower wrote parts of the parser, RTL generator, and RTL
+ definitions, and of the VAX machine description.
+
+ * Tom Tromey for internationalization support and for his many Java
+ contributions and libgcj maintainership.
+
+ * Lassi Tuura for improvements to config.guess to determine HP
+ processor types.
+
+ * Petter Urkedal for libstdc++ CXXFLAGS, math, and algorithms fixes.
+
+ * Brent Verner for work with the libstdc++ cshadow files and their
+ associated configure steps.
+
+ * Todd Vierling for contributions for NetBSD ports.
+
+ * Jonathan Wakely for contributing libstdc++ Doxygen notes and XHTML
+ guidance.
+
+ * Dean Wakerley for converting the install documentation from HTML
+ to texinfo in time for GCC 3.0.
+
+ * Krister Walfridsson for random bugfixes.
+
+ * Stephen M. Webb for time and effort on making libstdc++ shadow
+ files work with the tricky Solaris 8+ headers, and for pushing the
+ build-time header tree.
+
+ * John Wehle for various improvements for the x86 code generator,
+ related infrastructure improvements to help x86 code generation,
+ value range propagation and other work, WE32k port.
+
+ * Zack Weinberg for major work on cpplib and various other bugfixes.
+
+ * Matt Welsh for help with Linux Threads support in GCJ.
+
+ * Urban Widmark for help fixing java.io.
+
+ * Mark Wielaard for new Java library code and his work integrating
+ with Classpath.
+
+ * Dale Wiles helped port GCC to the Tahoe.
+
+ * Bob Wilson from Tensilica, Inc. for the Xtensa port.
+
+ * Jim Wilson for his direction via the steering committee, tackling
+ hard problems in various places that nobody else wanted to work
+ on, strength reduction and other loop optimizations.
+
+ * Carlo Wood for various fixes.
+
+ * Tom Wood for work on the m88k port.
+
+ * Masanobu Yuhara of Fujitsu Laboratories implemented the machine
+ description for the Tron architecture (specifically, the Gmicro).
+
+ * Kevin Zachmann helped ported GCC to the Tahoe.
+
+ * Gilles Zunino for help porting Java to Irix.
+
+
+ We'd also like to thank the folks who have contributed time and
+energy in testing GCC:
+
+ * Michael Abd-El-Malek
+
+ * Thomas Arend
+
+ * Bonzo Armstrong
+
+ * Steven Ashe
+
+ * Chris Baldwin
+
+ * David Billinghurst
+
+ * Jim Blandy
+
+ * Stephane Bortzmeyer
+
+ * Horst von Brand
+
+ * Frank Braun
+
+ * Rodney Brown
+
+ * Joe Buck
+
+ * Craig Burley
+
+ * Sidney Cadot
+
+ * Bradford Castalia
+
+ * Ralph Doncaster
+
+ * Ulrich Drepper
+
+ * David Edelsohn
+
+ * Richard Emberson
+
+ * Levente Farkas
+
+ * Graham Fawcett
+
+ * Robert A. French
+
+ * Jo"rgen Freyh
+
+ * Mark K. Gardner
+
+ * Charles-Antoine Gauthier
+
+ * Yung Shing Gene
+
+ * Kaveh Ghazi
+
+ * David Gilbert
+
+ * Simon Gornall
+
+ * Fred Gray
+
+ * John Griffin
+
+ * Patrik Hagglund
+
+ * Phil Hargett
+
+ * Amancio Hasty
+
+ * Bryan W. Headley
+
+ * Kate Hedstrom
+
+ * Richard Henderson
+
+ * Kevin B. Hendricks
+
+ * Manfred Hollstein
+
+ * Kamil Iskra
+
+ * Joep Jansen
+
+ * Christian Joensson
+
+ * David Kidd
+
+ * Tobias Kuipers
+
+ * Anand Krishnaswamy
+
+ * Jeff Law
+
+ * Robert Lipe
+
+ * llewelly
+
+ * Damon Love
+
+ * Dave Love
+
+ * H.J. Lu
+
+ * Brad Lucier
+
+ * Mumit Khan
+
+ * Matthias Klose
+
+ * Martin Knoblauch
+
+ * Jesse Macnish
+
+ * David Miller
+
+ * Toon Moene
+
+ * Stefan Morrell
+
+ * Anon A. Mous
+
+ * Matthias Mueller
+
+ * Pekka Nikander
+
+ * Alexandre Oliva
+
+ * Jon Olson
+
+ * Magnus Persson
+
+ * Chris Pollard
+
+ * Richard Polton
+
+ * David Rees
+
+ * Paul Reilly
+
+ * Tom Reilly
+
+ * Loren J. Rittle
+
+ * Torsten Rueger
+
+ * Danny Sadinoff
+
+ * Marc Schifer
+
+ * Peter Schmid
+
+ * David Schuler
+
+ * Vin Shelton
+
+ * Franz Sirl
+
+ * Tim Souder
+
+ * Mike Stump
+
+ * Adam Sulmicki
+
+ * George Talbot
+
+ * Gregory Warnes
+
+ * Carlo Wood
+
+ * David E. Young
+
+ * And many others
+
+ And finally we'd like to thank everyone who uses the compiler,
+submits bug reports and generally reminds us why we're doing this work
+in the first place.
+
+\1f
+File: gcc.info, Node: Option Index, Next: Index, Prev: Contributors, Up: Top
+
+Option Index
+************
+
+GCC's command line options are indexed here without any initial `-' or
+`--'. Where an option has both positive and negative forms (such as
+`-fOPTION' and `-fno-OPTION'), relevant entries in the manual are
+indexed under the most appropriate form; it may sometimes be useful to
+look up both forms.
+
+\0\b[index\0\b]
+* Menu:
+
+* ###: Overall Options. (line 166)
+* $: Preprocessor Options.
+ (line 457)
+* A: Preprocessor Options.
+ (line 366)
+* A-: Preprocessor Options.
+ (line 375)
+* ansi <1>: Non-bugs. (line 102)
+* ansi <2>: Other Builtins. (line 22)
+* ansi <3>: Preprocessor Options.
+ (line 246)
+* ansi <4>: C Dialect Options. (line 10)
+* ansi: Standards. (line 13)
+* aux-info: C Dialect Options. (line 92)
+* b: Target Options. (line 17)
+* B: Directory Options. (line 55)
+* bcopy-builtin: PDP-11 Options. (line 32)
+* c: Link Options. (line 20)
+* C: Preprocessor Options.
+ (line 419)
+* c: Overall Options. (line 118)
+* D: Preprocessor Options.
+ (line 23)
+* d: Debugging Options. (line 197)
+* da: Debugging Options. (line 309)
+* dA: Debugging Options. (line 205)
+* dB: Debugging Options. (line 212)
+* db: Debugging Options. (line 209)
+* dC: Debugging Options. (line 219)
+* dc: Debugging Options. (line 215)
+* dD <1>: Preprocessor Options.
+ (line 400)
+* dD: Debugging Options. (line 225)
+* dd: Debugging Options. (line 222)
+* dE: Debugging Options. (line 233)
+* de: Debugging Options. (line 229)
+* dF: Debugging Options. (line 239)
+* df: Debugging Options. (line 236)
+* dG: Debugging Options. (line 254)
+* dg: Debugging Options. (line 242)
+* dh: Debugging Options. (line 245)
+* dI: Preprocessor Options.
+ (line 409)
+* di: Debugging Options. (line 257)
+* dj: Debugging Options. (line 260)
+* dk: Debugging Options. (line 248)
+* dL: Debugging Options. (line 270)
+* dl: Debugging Options. (line 267)
+* dM: Preprocessor Options.
+ (line 388)
+* dm: Debugging Options. (line 312)
+* dM: Debugging Options. (line 273)
+* dN <1>: Preprocessor Options.
+ (line 406)
+* dN: Debugging Options. (line 280)
+* dn: Debugging Options. (line 277)
+* do: Debugging Options. (line 251)
+* dP: Debugging Options. (line 321)
+* dp: Debugging Options. (line 316)
+* dR: Debugging Options. (line 286)
+* dr: Debugging Options. (line 283)
+* dS: Debugging Options. (line 293)
+* ds: Debugging Options. (line 289)
+* dt: Debugging Options. (line 296)
+* dumpmachine: Debugging Options. (line 480)
+* dumpspecs: Debugging Options. (line 488)
+* dumpversion: Debugging Options. (line 484)
+* dv: Debugging Options. (line 325)
+* dw: Debugging Options. (line 300)
+* dx: Debugging Options. (line 330)
+* dX: Debugging Options. (line 303)
+* dy: Debugging Options. (line 334)
+* dz: Debugging Options. (line 306)
+* E <1>: Link Options. (line 20)
+* E: Overall Options. (line 139)
+* EB <1>: ARC Options. (line 12)
+* EB: MIPS Options. (line 249)
+* EL <1>: ARC Options. (line 9)
+* EL: MIPS Options. (line 245)
+* falign-functions: Optimize Options. (line 558)
+* falign-jumps: Optimize Options. (line 596)
+* falign-labels: Optimize Options. (line 574)
+* falign-loops: Optimize Options. (line 587)
+* fallow-single-precision: C Dialect Options. (line 293)
+* falt-external-templates <1>: Template Instantiation.
+ (line 157)
+* falt-external-templates: C++ Dialect Options. (line 86)
+* fargument-alias: Code Gen Options. (line 318)
+* fargument-noalias: Code Gen Options. (line 318)
+* fargument-noalias-global: Code Gen Options. (line 318)
+* fbounds-check: Optimize Options. (line 259)
+* fbranch-probabilities: Optimize Options. (line 482)
+* fcall-saved <1>: Interoperation. (line 226)
+* fcall-saved: Code Gen Options. (line 225)
+* fcall-used: Code Gen Options. (line 211)
+* fcaller-saves: Optimize Options. (line 420)
+* fcheck-new: C++ Dialect Options. (line 24)
+* fcond-mismatch: C Dialect Options. (line 242)
+* fconserve-space: C++ Dialect Options. (line 35)
+* fconstant-string-class: Objective-C Dialect Options.
+ (line 21)
+* fcse-follow-jumps: Optimize Options. (line 290)
+* fcse-skip-blocks: Optimize Options. (line 297)
+* fdata-sections: Optimize Options. (line 400)
+* fdelayed-branch: Optimize Options. (line 359)
+* fdelete-null-pointer-checks: Optimize Options. (line 333)
+* fdiagnostics-show-location: Language Independent Options.
+ (line 21)
+* fdollars-in-identifiers <1>: Interoperation. (line 193)
+* fdollars-in-identifiers: C++ Dialect Options. (line 58)
+* fdump-class-hierarchy: Debugging Options. (line 353)
+* fdump-translation-unit: Debugging Options. (line 345)
+* fdump-tree: Debugging Options. (line 361)
+* fdump-unnumbered: Debugging Options. (line 337)
+* fexceptions: Code Gen Options. (line 15)
+* fexpensive-optimizations: Optimize Options. (line 344)
+* fexternal-templates <1>: Template Instantiation.
+ (line 135)
+* fexternal-templates: C++ Dialect Options. (line 78)
+* ffast-math: Optimize Options. (line 208)
+* ffixed: Code Gen Options. (line 199)
+* ffloat-store <1>: Disappointments. (line 79)
+* ffloat-store: Optimize Options. (line 64)
+* ffor-scope: C++ Dialect Options. (line 95)
+* fforce-addr: Optimize Options. (line 98)
+* fforce-mem: Optimize Options. (line 91)
+* ffreestanding <1>: Function Attributes. (line 153)
+* ffreestanding <2>: C Dialect Options. (line 164)
+* ffreestanding: Standards. (line 87)
+* ffunction-sections: Optimize Options. (line 400)
+* fgcse: Optimize Options. (line 310)
+* fgcse-lm: Optimize Options. (line 319)
+* fgcse-sm: Optimize Options. (line 326)
+* fgnu-runtime: Objective-C Dialect Options.
+ (line 26)
+* fhosted: C Dialect Options. (line 157)
+* finhibit-size-directive: Code Gen Options. (line 145)
+* finline-functions: Optimize Options. (line 130)
+* finline-limit: Optimize Options. (line 139)
+* finstrument-functions <1>: Function Attributes. (line 204)
+* finstrument-functions: Code Gen Options. (line 250)
+* fkeep-inline-functions <1>: Inline. (line 51)
+* fkeep-inline-functions: Optimize Options. (line 158)
+* fkeep-static-consts: Optimize Options. (line 164)
+* fleading-underscore: Code Gen Options. (line 333)
+* fmem-report: Debugging Options. (line 139)
+* fmessage-length: Language Independent Options.
+ (line 15)
+* fmove-all-movables: Optimize Options. (line 451)
+* fms-extensions: C++ Dialect Options. (line 130)
+* fnext-runtime: Objective-C Dialect Options.
+ (line 30)
+* fno-access-control: C++ Dialect Options. (line 20)
+* fno-asm: C Dialect Options. (line 108)
+* fno-branch-count-reg: Optimize Options. (line 191)
+* fno-builtin <1>: Other Builtins. (line 14)
+* fno-builtin: C Dialect Options. (line 122)
+* fno-common <1>: Variable Attributes. (line 89)
+* fno-common: Code Gen Options. (line 123)
+* fno-const-strings: C++ Dialect Options. (line 47)
+* fno-cprop-registers: Optimize Options. (line 630)
+* fno-default-inline <1>: Inline. (line 46)
+* fno-default-inline <2>: Optimize Options. (line 78)
+* fno-default-inline: C++ Dialect Options. (line 214)
+* fno-defer-pop: Optimize Options. (line 85)
+* fno-elide-constructors: C++ Dialect Options. (line 65)
+* fno-enforce-eh-specs: C++ Dialect Options. (line 71)
+* fno-for-scope: C++ Dialect Options. (line 95)
+* fno-function-cse: Optimize Options. (line 199)
+* fno-gnu-keywords: C++ Dialect Options. (line 107)
+* fno-gnu-linker: Code Gen Options. (line 135)
+* fno-guess-branch-probability: Optimize Options. (line 502)
+* fno-ident: Code Gen Options. (line 132)
+* fno-implement-inlines <1>: C++ Interface. (line 91)
+* fno-implement-inlines: C++ Dialect Options. (line 124)
+* fno-implicit-inline-templates: C++ Dialect Options. (line 118)
+* fno-implicit-templates <1>: Template Instantiation.
+ (line 87)
+* fno-implicit-templates: C++ Dialect Options. (line 112)
+* fno-inline: Optimize Options. (line 124)
+* fno-math-errno: Optimize Options. (line 220)
+* fno-nonansi-builtins: C++ Dialect Options. (line 135)
+* fno-operator-names: C++ Dialect Options. (line 140)
+* fno-optional-diags: C++ Dialect Options. (line 144)
+* fno-peephole: Optimize Options. (line 476)
+* fno-peephole2: Optimize Options. (line 476)
+* fno-rtti: C++ Dialect Options. (line 161)
+* fno-sched-interblock: Optimize Options. (line 379)
+* fno-sched-spec: Optimize Options. (line 384)
+* fno-show-column: Preprocessor Options.
+ (line 361)
+* fno-signed-bitfields: C Dialect Options. (line 275)
+* fno-stack-limit: Code Gen Options. (line 302)
+* fno-trapping-math: Optimize Options. (line 247)
+* fno-unsigned-bitfields: C Dialect Options. (line 275)
+* fno-weak: C++ Dialect Options. (line 199)
+* fnon-call-exceptions: Code Gen Options. (line 29)
+* fomit-frame-pointer: Optimize Options. (line 103)
+* foptimize-register-move: Optimize Options. (line 349)
+* foptimize-sibling-calls: Optimize Options. (line 117)
+* fpack-struct: Code Gen Options. (line 242)
+* fpcc-struct-return <1>: Incompatibilities. (line 197)
+* fpcc-struct-return: Code Gen Options. (line 51)
+* fpermissive: C++ Dialect Options. (line 149)
+* fPIC: Code Gen Options. (line 190)
+* fpic: Code Gen Options. (line 172)
+* fprefetch-loop-arrays: Optimize Options. (line 446)
+* fpreprocessed: Preprocessor Options.
+ (line 342)
+* fpretend-float: Debugging Options. (line 409)
+* fprofile-arcs <1>: Other Builtins. (line 190)
+* fprofile-arcs: Debugging Options. (line 143)
+* freduce-all-givs: Optimize Options. (line 455)
+* freg-struct-return: Code Gen Options. (line 69)
+* fregmove: Optimize Options. (line 349)
+* frename-registers: Optimize Options. (line 623)
+* frepo <1>: Template Instantiation.
+ (line 62)
+* frepo: C++ Dialect Options. (line 156)
+* frerun-cse-after-loop: Optimize Options. (line 303)
+* frerun-loop-opt: Optimize Options. (line 307)
+* fsched-spec-load: Optimize Options. (line 389)
+* fsched-spec-load-dangerous: Optimize Options. (line 394)
+* fsched-verbose: Debugging Options. (line 394)
+* fschedule-insns: Optimize Options. (line 364)
+* fschedule-insns2: Optimize Options. (line 372)
+* fshared-data: Code Gen Options. (line 116)
+* fshort-double: Code Gen Options. (line 98)
+* fshort-enums <1>: Non-bugs. (line 37)
+* fshort-enums <2>: Type Attributes. (line 110)
+* fshort-enums: Code Gen Options. (line 87)
+* fshort-wchar: Code Gen Options. (line 106)
+* fsigned-bitfields <1>: Non-bugs. (line 52)
+* fsigned-bitfields: C Dialect Options. (line 275)
+* fsigned-char: C Dialect Options. (line 265)
+* fsingle-precision-constant: Optimize Options. (line 619)
+* fssa: Optimize Options. (line 604)
+* fssa-ccp: Optimize Options. (line 611)
+* fssa-dce: Optimize Options. (line 615)
+* fstack-check: Code Gen Options. (line 287)
+* fstack-limit-register: Code Gen Options. (line 302)
+* fstack-limit-symbol: Code Gen Options. (line 302)
+* fstats: C++ Dialect Options. (line 169)
+* fstrength-reduce: Optimize Options. (line 279)
+* fstrict-aliasing: Optimize Options. (line 517)
+* fsyntax-only: Warning Options. (line 22)
+* ftabstop: Preprocessor Options.
+ (line 355)
+* ftemplate-depth: C++ Dialect Options. (line 174)
+* ftest-coverage: Debugging Options. (line 170)
+* fthread-jumps: Optimize Options. (line 283)
+* ftime-report: Debugging Options. (line 135)
+* ftrapv: Optimize Options. (line 120)
+* funroll-all-loops: Optimize Options. (line 440)
+* funroll-loops <1>: Non-bugs. (line 168)
+* funroll-loops: Optimize Options. (line 434)
+* funsafe-math-optimizations: Optimize Options. (line 233)
+* funsigned-bitfields <1>: Non-bugs. (line 52)
+* funsigned-bitfields: C Dialect Options. (line 275)
+* funsigned-char: C Dialect Options. (line 247)
+* funwind-tables: Code Gen Options. (line 38)
+* fuse-cxa-atexit: C++ Dialect Options. (line 181)
+* fverbose-asm: Code Gen Options. (line 152)
+* fvolatile: Code Gen Options. (line 161)
+* fvolatile-global: Code Gen Options. (line 164)
+* fvolatile-static: Code Gen Options. (line 169)
+* fvtable-gc: C++ Dialect Options. (line 188)
+* fwritable-strings <1>: Incompatibilities. (line 24)
+* fwritable-strings: C Dialect Options. (line 284)
+* G <1>: System V Options. (line 10)
+* G <2>: MIPS Options. (line 253)
+* G <3>: RS/6000 and PowerPC Options.
+ (line 458)
+* G: M32R/D Options. (line 54)
+* g: Debugging Options. (line 10)
+* gcc: Preprocessor Options.
+ (line 431)
+* gcoff: Debugging Options. (line 59)
+* gdwarf: Debugging Options. (line 77)
+* gdwarf+: Debugging Options. (line 82)
+* gdwarf-2: Debugging Options. (line 88)
+* gen-decls: Objective-C Dialect Options.
+ (line 34)
+* ggdb: Debugging Options. (line 39)
+* gstabs: Debugging Options. (line 45)
+* gstabs+: Debugging Options. (line 53)
+* gvms: Debugging Options. (line 92)
+* gxcoff: Debugging Options. (line 64)
+* gxcoff+: Debugging Options. (line 69)
+* H: Preprocessor Options.
+ (line 472)
+* h: Preprocessor Options.
+ (line 464)
+* help <1>: Preprocessor Options.
+ (line 464)
+* help: Overall Options. (line 177)
+* I <1>: Directory Options. (line 10)
+* I: Preprocessor Options.
+ (line 51)
+* I- <1>: Directory Options. (line 31)
+* I-: Preprocessor Options.
+ (line 276)
+* idirafter: Preprocessor Options.
+ (line 317)
+* imacros: Preprocessor Options.
+ (line 308)
+* include: Preprocessor Options.
+ (line 297)
+* iprefix: Preprocessor Options.
+ (line 322)
+* isystem: Preprocessor Options.
+ (line 336)
+* iwithprefix: Preprocessor Options.
+ (line 328)
+* iwithprefixbefore: Preprocessor Options.
+ (line 328)
+* L: Directory Options. (line 51)
+* l: Link Options. (line 26)
+* lobjc: Link Options. (line 53)
+* M: Preprocessor Options.
+ (line 123)
+* m1: SH Options. (line 9)
+* m10: PDP-11 Options. (line 29)
+* m128bit-long-double: i386 and x86-64 Options.
+ (line 141)
+* m16-bit: CRIS Options. (line 64)
+* m2: SH Options. (line 12)
+* m210: MCore Options. (line 52)
+* m29000: AMD29K Options. (line 45)
+* m29050: AMD29K Options. (line 42)
+* m3: SH Options. (line 15)
+* m31: S/390 and zSeries Options.
+ (line 34)
+* m32 <1>: i386 and x86-64 Options.
+ (line 293)
+* m32: SPARC Options. (line 190)
+* m32-bit: CRIS Options. (line 64)
+* m32032: NS32K Options. (line 13)
+* m32081: NS32K Options. (line 27)
+* m32332: NS32K Options. (line 18)
+* m32381: NS32K Options. (line 31)
+* m32532: NS32K Options. (line 23)
+* m32r: M32R/D Options. (line 12)
+* m32rx: M32R/D Options. (line 9)
+* m340: MCore Options. (line 52)
+* m386: i386 and x86-64 Options.
+ (line 33)
+* m3dnow: i386 and x86-64 Options.
+ (line 235)
+* m3e: SH Options. (line 18)
+* m4: SH Options. (line 32)
+* m4-nofpu: SH Options. (line 21)
+* m4-single: SH Options. (line 28)
+* m4-single-only: SH Options. (line 24)
+* m40: PDP-11 Options. (line 23)
+* m45: PDP-11 Options. (line 26)
+* m4650: MIPS Options. (line 233)
+* m486: i386 and x86-64 Options.
+ (line 33)
+* m4byte-functions: MCore Options. (line 32)
+* m5200: M680x0 Options. (line 59)
+* m64 <1>: S/390 and zSeries Options.
+ (line 34)
+* m64 <2>: i386 and x86-64 Options.
+ (line 293)
+* m64: SPARC Options. (line 190)
+* m68000: M680x0 Options. (line 13)
+* m68020: M680x0 Options. (line 21)
+* m68020-40: M680x0 Options. (line 66)
+* m68020-60: M680x0 Options. (line 73)
+* m68030: M680x0 Options. (line 30)
+* m68040: M680x0 Options. (line 34)
+* m68060: M680x0 Options. (line 42)
+* m6811: M68hc1x Options. (line 13)
+* m6812: M68hc1x Options. (line 18)
+* m68881: M680x0 Options. (line 25)
+* m68hc11: M68hc1x Options. (line 13)
+* m68hc12: M68hc1x Options. (line 18)
+* m8-bit: CRIS Options. (line 64)
+* m88000: M88K Options. (line 9)
+* m88100: M88K Options. (line 12)
+* m88110: M88K Options. (line 16)
+* m96bit-long-double: i386 and x86-64 Options.
+ (line 153)
+* mabi-mmixware: MMIX Options. (line 20)
+* mabi=32: MIPS Options. (line 101)
+* mabi=64: MIPS Options. (line 101)
+* mabi=altivec: RS/6000 and PowerPC Options.
+ (line 357)
+* mabi=eabi: MIPS Options. (line 101)
+* mabi=gnu: MMIX Options. (line 20)
+* mabi=n32: MIPS Options. (line 101)
+* mabi=no-altivec: RS/6000 and PowerPC Options.
+ (line 362)
+* mabi=o64: MIPS Options. (line 101)
+* mabicalls: MIPS Options. (line 182)
+* mabort-on-noreturn: ARM Options. (line 186)
+* mabshi: PDP-11 Options. (line 56)
+* mac0: PDP-11 Options. (line 16)
+* maccumulate-outgoing-args: i386 and x86-64 Options.
+ (line 254)
+* mads: RS/6000 and PowerPC Options.
+ (line 387)
+* maix-struct-return: RS/6000 and PowerPC Options.
+ (line 350)
+* maix32: RS/6000 and PowerPC Options.
+ (line 188)
+* maix64: RS/6000 and PowerPC Options.
+ (line 188)
+* malign-300: H8/300 Options. (line 27)
+* malign-double: i386 and x86-64 Options.
+ (line 128)
+* malign-int: M680x0 Options. (line 128)
+* malignment-traps: ARM Options. (line 83)
+* malpha-as: DEC Alpha Options. (line 159)
+* maltivec: RS/6000 and PowerPC Options.
+ (line 152)
+* mam33: MN10300 Options. (line 17)
+* maout: CRIS Options. (line 87)
+* mapcs: ARM Options. (line 18)
+* mapcs-26: ARM Options. (line 21)
+* mapcs-32: ARM Options. (line 27)
+* mapcs-frame: ARM Options. (line 10)
+* mapp-regs: SPARC Options. (line 10)
+* march <1>: CRIS Options. (line 10)
+* march <2>: HPPA Options. (line 9)
+* march <3>: i386 and x86-64 Options.
+ (line 25)
+* march <4>: MIPS Options. (line 9)
+* march: ARM Options. (line 159)
+* margcount: Convex Options. (line 33)
+* masm-compat: Intel 960 Options. (line 58)
+* masm-optimize: D30V Options. (line 24)
+* masm=DIALECT: i386 and x86-64 Options.
+ (line 85)
+* mauto-incdec: M68hc1x Options. (line 22)
+* mauto-pic: IA-64 Options. (line 53)
+* mb: SH Options. (line 35)
+* mb-step: IA-64 Options. (line 36)
+* mbackchain: S/390 and zSeries Options.
+ (line 20)
+* mbase-addresses: MMIX Options. (line 54)
+* mbcopy: PDP-11 Options. (line 36)
+* mbig <1>: TMS320C3x/C4x Options.
+ (line 19)
+* mbig: RS/6000 and PowerPC Options.
+ (line 311)
+* mbig-endian <1>: Xtensa Options. (line 14)
+* mbig-endian <2>: IA-64 Options. (line 9)
+* mbig-endian <3>: MCore Options. (line 47)
+* mbig-endian <4>: RS/6000 and PowerPC Options.
+ (line 311)
+* mbig-endian: ARM Options. (line 71)
+* mbig-memory: TMS320C3x/C4x Options.
+ (line 19)
+* mbig-pic: M88K Options. (line 20)
+* mbig-switch <1>: V850 Options. (line 52)
+* mbig-switch: HPPA Options. (line 27)
+* mbigtable: SH Options. (line 51)
+* mbit-align: RS/6000 and PowerPC Options.
+ (line 265)
+* mbitfield <1>: NS32K Options. (line 59)
+* mbitfield: M680x0 Options. (line 100)
+* mbk: TMS320C3x/C4x Options.
+ (line 28)
+* mbooleans: Xtensa Options. (line 69)
+* mbranch-cheap: PDP-11 Options. (line 66)
+* mbranch-cost: D30V Options. (line 29)
+* mbranch-expensive: PDP-11 Options. (line 62)
+* mbranch-predict: MMIX Options. (line 49)
+* mbroken-saverestore: SPARC Options. (line 173)
+* mbsd: ARM Options. (line 122)
+* mbuild-constants: DEC Alpha Options. (line 142)
+* mbw: AMD29K Options. (line 17)
+* mbwx: DEC Alpha Options. (line 171)
+* mc1: Convex Options. (line 9)
+* mc2: Convex Options. (line 13)
+* mc300: Clipper Options. (line 9)
+* mc32: Convex Options. (line 18)
+* mc34: Convex Options. (line 23)
+* mc38: Convex Options. (line 28)
+* mc400: Clipper Options. (line 12)
+* mc68000: M680x0 Options. (line 13)
+* mc68020: M680x0 Options. (line 21)
+* mca: Intel 960 Options. (line 9)
+* mcall-aix: RS/6000 and PowerPC Options.
+ (line 329)
+* mcall-gnu: RS/6000 and PowerPC Options.
+ (line 342)
+* mcall-lib-mul: RT Options. (line 13)
+* mcall-linux: RS/6000 and PowerPC Options.
+ (line 338)
+* mcall-netbsd: RS/6000 and PowerPC Options.
+ (line 346)
+* mcall-prologues: AVR Options. (line 43)
+* mcall-solaris: RS/6000 and PowerPC Options.
+ (line 334)
+* mcall-sysv: RS/6000 and PowerPC Options.
+ (line 316)
+* mcall-sysv-eabi: RS/6000 and PowerPC Options.
+ (line 323)
+* mcall-sysv-noeabi: RS/6000 and PowerPC Options.
+ (line 326)
+* mcallee-super-interworking: ARM Options. (line 266)
+* mcaller-super-interworking: ARM Options. (line 272)
+* mcallgraph-data: MCore Options. (line 37)
+* mcc-init: CRIS Options. (line 41)
+* mcf: Intel 960 Options. (line 9)
+* mcheck-zero-division: M88K Options. (line 123)
+* mcix: DEC Alpha Options. (line 171)
+* mcmodel=embmedany: SPARC Options. (line 212)
+* mcmodel=kernel: i386 and x86-64 Options.
+ (line 314)
+* mcmodel=large: i386 and x86-64 Options.
+ (line 326)
+* mcmodel=medany: SPARC Options. (line 206)
+* mcmodel=medium: i386 and x86-64 Options.
+ (line 319)
+* mcmodel=medlow: SPARC Options. (line 195)
+* mcmodel=medmid: SPARC Options. (line 200)
+* mcmodel=small: i386 and x86-64 Options.
+ (line 308)
+* mcode-align: Intel 960 Options. (line 47)
+* mcode-model=large: M32R/D Options. (line 30)
+* mcode-model=medium: M32R/D Options. (line 24)
+* mcode-model=small: M32R/D Options. (line 15)
+* mcomplex-addr: Intel 960 Options. (line 39)
+* mcond-exec: D30V Options. (line 34)
+* mconst-align: CRIS Options. (line 55)
+* mconstant-gp: IA-64 Options. (line 49)
+* mcpu <1>: CRIS Options. (line 10)
+* mcpu <2>: ARC Options. (line 23)
+* mcpu <3>: TMS320C3x/C4x Options.
+ (line 9)
+* mcpu <4>: DEC Alpha Options. (line 212)
+* mcpu <5>: i386 and x86-64 Options.
+ (line 10)
+* mcpu <6>: MIPS Options. (line 29)
+* mcpu <7>: RS/6000 and PowerPC Options.
+ (line 82)
+* mcpu <8>: ARM Options. (line 138)
+* mcpu: SPARC Options. (line 131)
+* mcpu32: M680x0 Options. (line 51)
+* mcypress: SPARC Options. (line 115)
+* MD: Preprocessor Options.
+ (line 208)
+* mdalign: SH Options. (line 41)
+* mdata: ARC Options. (line 30)
+* mdata-align: CRIS Options. (line 55)
+* mdb: TMS320C3x/C4x Options.
+ (line 33)
+* mdebug: S/390 and zSeries Options.
+ (line 48)
+* mdec-asm: PDP-11 Options. (line 79)
+* mdensity: Xtensa Options. (line 19)
+* mdisable-fpregs: HPPA Options. (line 37)
+* mdisable-indexing: HPPA Options. (line 44)
+* mdiv: MCore Options. (line 17)
+* mdouble-float: MIPS Options. (line 222)
+* mdp-isr-reload: TMS320C3x/C4x Options.
+ (line 46)
+* mdw: AMD29K Options. (line 9)
+* mdwarf2-asm: IA-64 Options. (line 66)
+* meabi: RS/6000 and PowerPC Options.
+ (line 406)
+* melf <1>: MMIX Options. (line 44)
+* melf: CRIS Options. (line 90)
+* melinux: CRIS Options. (line 94)
+* melinux-stacksize: CRIS Options. (line 25)
+* memb: RS/6000 and PowerPC Options.
+ (line 401)
+* membedded-data: MIPS Options. (line 209)
+* membedded-pic: MIPS Options. (line 200)
+* mentry: MIPS Options. (line 241)
+* mep: V850 Options. (line 16)
+* mepsilon: MMIX Options. (line 15)
+* metrax100: CRIS Options. (line 31)
+* metrax4: CRIS Options. (line 31)
+* mexplicit-relocs: DEC Alpha Options. (line 184)
+* mextmem: D30V Options. (line 9)
+* mextmemory: D30V Options. (line 14)
+* MF: Preprocessor Options.
+ (line 156)
+* mfast-fix: TMS320C3x/C4x Options.
+ (line 63)
+* mfast-indirect-calls: HPPA Options. (line 56)
+* mfaster-structs: SPARC Options. (line 85)
+* mfix: DEC Alpha Options. (line 171)
+* mfix7000: MIPS Options. (line 267)
+* mfixed-range: IA-64 Options. (line 71)
+* mflat: SPARC Options. (line 59)
+* mfloat-ieee: DEC Alpha Options. (line 179)
+* mfloat-vax: DEC Alpha Options. (line 179)
+* mfloat32: PDP-11 Options. (line 53)
+* mfloat64: PDP-11 Options. (line 48)
+* mflush-func: MIPS Options. (line 276)
+* mfmovd: SH Options. (line 55)
+* mfp: ARM Options. (line 168)
+* mfp-arg-in-fpregs: RT Options. (line 26)
+* mfp-arg-in-gregs: RT Options. (line 33)
+* mfp-reg: DEC Alpha Options. (line 25)
+* mfp-rounding-mode: DEC Alpha Options. (line 85)
+* mfp-trap-mode: DEC Alpha Options. (line 63)
+* mfp32: MIPS Options. (line 50)
+* mfp64: MIPS Options. (line 54)
+* mfpa: M680x0 Options. (line 80)
+* mfpe: ARM Options. (line 168)
+* mfpu <1>: PDP-11 Options. (line 9)
+* mfpu: SPARC Options. (line 20)
+* mfull-fp-blocks: RT Options. (line 16)
+* mfull-toc: RS/6000 and PowerPC Options.
+ (line 161)
+* mfused-madd <1>: Xtensa Options. (line 85)
+* mfused-madd <2>: MIPS Options. (line 59)
+* mfused-madd: RS/6000 and PowerPC Options.
+ (line 259)
+* mg: VAX Options. (line 17)
+* MG: Preprocessor Options.
+ (line 165)
+* mgas <1>: DEC Alpha Options. (line 159)
+* mgas <2>: HPPA Options. (line 72)
+* mgas: MIPS Options. (line 115)
+* mgnu: VAX Options. (line 13)
+* mgnu-as: IA-64 Options. (line 18)
+* mgnu-ld: IA-64 Options. (line 23)
+* mgotplt: CRIS Options. (line 81)
+* mgp32: MIPS Options. (line 68)
+* mgp64: MIPS Options. (line 72)
+* mgpopt: MIPS Options. (line 137)
+* mh: H8/300 Options. (line 14)
+* mhalf-pic: MIPS Options. (line 195)
+* mhandle-large-shift: M88K Options. (line 169)
+* mhard-float <1>: Xtensa Options. (line 76)
+* mhard-float <2>: S/390 and zSeries Options.
+ (line 11)
+* mhard-float <3>: MIPS Options. (line 177)
+* mhard-float <4>: RS/6000 and PowerPC Options.
+ (line 221)
+* mhard-float <5>: ARM Options. (line 49)
+* mhard-float: SPARC Options. (line 20)
+* mhard-quad-float: SPARC Options. (line 41)
+* mhardlit: MCore Options. (line 11)
+* mhc-struct-return <1>: Interoperation. (line 221)
+* mhc-struct-return: RT Options. (line 37)
+* mhimem: NS32K Options. (line 104)
+* mhitachi: SH Options. (line 58)
+* mic-compat: Intel 960 Options. (line 54)
+* mic2.0-compat: Intel 960 Options. (line 54)
+* mic3.0-compat: Intel 960 Options. (line 54)
+* midentify-revision: M88K Options. (line 23)
+* mieee <1>: SH Options. (line 65)
+* mieee: DEC Alpha Options. (line 39)
+* mieee-conformant: DEC Alpha Options. (line 134)
+* mieee-fp: i386 and x86-64 Options.
+ (line 90)
+* mieee-with-inexact: DEC Alpha Options. (line 52)
+* mimpure-text: AMD29K Options. (line 79)
+* min-line-mul: RT Options. (line 9)
+* minit-stack: AVR Options. (line 35)
+* minline-all-stringops: i386 and x86-64 Options.
+ (line 275)
+* minline-divide-max-throughput: IA-64 Options. (line 61)
+* minline-divide-min-latency: IA-64 Options. (line 57)
+* mint16: PDP-11 Options. (line 40)
+* mint32 <1>: PDP-11 Options. (line 44)
+* mint32: H8/300 Options. (line 24)
+* mint64: MIPS Options. (line 76)
+* mintel-asm: Intel 960 Options. (line 58)
+* mips1: MIPS Options. (line 32)
+* mips16: MIPS Options. (line 238)
+* mips2: MIPS Options. (line 36)
+* mips3: MIPS Options. (line 41)
+* mips4: MIPS Options. (line 45)
+* misize: SH Options. (line 68)
+* mjump-in-delay: HPPA Options. (line 32)
+* mka: Intel 960 Options. (line 9)
+* mkb: Intel 960 Options. (line 9)
+* mkernel-registers: AMD29K Options. (line 48)
+* mknuthdiv: MMIX Options. (line 33)
+* ml: SH Options. (line 38)
+* mlarge: AMD29K Options. (line 38)
+* mlarge-data: DEC Alpha Options. (line 195)
+* mleaf-procedures: Intel 960 Options. (line 22)
+* mlibfuncs: MMIX Options. (line 10)
+* mlinker-opt: HPPA Options. (line 81)
+* mlinux: CRIS Options. (line 99)
+* mlittle: RS/6000 and PowerPC Options.
+ (line 305)
+* mlittle-endian <1>: Xtensa Options. (line 14)
+* mlittle-endian <2>: IA-64 Options. (line 13)
+* mlittle-endian <3>: MCore Options. (line 47)
+* mlittle-endian <4>: RS/6000 and PowerPC Options.
+ (line 305)
+* mlittle-endian <5>: ARM Options. (line 67)
+* mlittle-endian: SPARC Options. (line 166)
+* mlive-g0: SPARC Options. (line 169)
+* mlong-calls <1>: V850 Options. (line 10)
+* mlong-calls <2>: MIPS Options. (line 188)
+* mlong-calls: ARM Options. (line 191)
+* mlong-double-64: Intel 960 Options. (line 70)
+* mlong-load-store: HPPA Options. (line 63)
+* mlong32 <1>: MIPS Options. (line 84)
+* mlong32: Convex Options. (line 53)
+* mlong64 <1>: MIPS Options. (line 80)
+* mlong64: Convex Options. (line 56)
+* mlongcalls: Xtensa Options. (line 133)
+* mloop-unsigned: TMS320C3x/C4x Options.
+ (line 95)
+* MM: Preprocessor Options.
+ (line 146)
+* mmac16: Xtensa Options. (line 24)
+* mmad: MIPS Options. (line 229)
+* mmangle-cpu: ARC Options. (line 15)
+* mmax: DEC Alpha Options. (line 171)
+* mmax-stack-frame: CRIS Options. (line 22)
+* mmc: Intel 960 Options. (line 9)
+* mmcu: AVR Options. (line 9)
+* MMD: Preprocessor Options.
+ (line 223)
+* mmemcpy: MIPS Options. (line 152)
+* mmemory-latency: DEC Alpha Options. (line 257)
+* mmemparm: TMS320C3x/C4x Options.
+ (line 110)
+* mminimal-toc: RS/6000 and PowerPC Options.
+ (line 161)
+* mminimum-fp-blocks: RT Options. (line 21)
+* mminmax: Xtensa Options. (line 59)
+* mmips-as: MIPS Options. (line 107)
+* mmips-tfile: MIPS Options. (line 158)
+* mmmx: i386 and x86-64 Options.
+ (line 235)
+* mmpyi: TMS320C3x/C4x Options.
+ (line 54)
+* mmul16: Xtensa Options. (line 34)
+* mmul32: Xtensa Options. (line 44)
+* mmult-bug: MN10300 Options. (line 9)
+* mmulti-add: NS32K Options. (line 37)
+* mmultiple: RS/6000 and PowerPC Options.
+ (line 227)
+* mmvcle: S/390 and zSeries Options.
+ (line 42)
+* mmvme: RS/6000 and PowerPC Options.
+ (line 382)
+* mnbw: AMD29K Options. (line 21)
+* mndw: AMD29K Options. (line 14)
+* mnew-mnemonics: RS/6000 and PowerPC Options.
+ (line 67)
+* mno-3dnow: i386 and x86-64 Options.
+ (line 235)
+* mno-4byte-functions: MCore Options. (line 32)
+* mno-abicalls: MIPS Options. (line 182)
+* mno-abshi: PDP-11 Options. (line 59)
+* mno-ac0: PDP-11 Options. (line 20)
+* mno-align-double: i386 and x86-64 Options.
+ (line 128)
+* mno-align-int: M680x0 Options. (line 128)
+* mno-align-stringops: i386 and x86-64 Options.
+ (line 270)
+* mno-alignment-traps: ARM Options. (line 100)
+* mno-altivec: RS/6000 and PowerPC Options.
+ (line 152)
+* mno-am33: MN10300 Options. (line 20)
+* mno-app-regs: SPARC Options. (line 10)
+* mno-asm-optimize: D30V Options. (line 24)
+* mno-backchain: S/390 and zSeries Options.
+ (line 20)
+* mno-base-addresses: MMIX Options. (line 54)
+* mno-bit-align: RS/6000 and PowerPC Options.
+ (line 265)
+* mno-bk: TMS320C3x/C4x Options.
+ (line 28)
+* mno-booleans: Xtensa Options. (line 69)
+* mno-branch-predict: MMIX Options. (line 49)
+* mno-bwx: DEC Alpha Options. (line 171)
+* mno-callgraph-data: MCore Options. (line 37)
+* mno-check-zero-division: M88K Options. (line 123)
+* mno-cix: DEC Alpha Options. (line 171)
+* mno-code-align: Intel 960 Options. (line 47)
+* mno-complex-addr: Intel 960 Options. (line 39)
+* mno-const-align: CRIS Options. (line 55)
+* mno-crt0: MN10300 Options. (line 24)
+* mno-data-align: CRIS Options. (line 55)
+* mno-db: TMS320C3x/C4x Options.
+ (line 33)
+* mno-debug: S/390 and zSeries Options.
+ (line 48)
+* mno-density: Xtensa Options. (line 19)
+* mno-div: MCore Options. (line 17)
+* mno-dwarf2-asm: IA-64 Options. (line 66)
+* mno-eabi: RS/6000 and PowerPC Options.
+ (line 406)
+* mno-embedded-data: MIPS Options. (line 209)
+* mno-embedded-pic: MIPS Options. (line 200)
+* mno-ep: V850 Options. (line 16)
+* mno-epsilon: MMIX Options. (line 15)
+* mno-explicit-relocs: DEC Alpha Options. (line 184)
+* mno-fancy-math-387: i386 and x86-64 Options.
+ (line 117)
+* mno-fast-fix: TMS320C3x/C4x Options.
+ (line 63)
+* mno-faster-structs: SPARC Options. (line 85)
+* mno-fix: DEC Alpha Options. (line 171)
+* mno-flat: SPARC Options. (line 59)
+* mno-float32: PDP-11 Options. (line 48)
+* mno-float64: PDP-11 Options. (line 53)
+* mno-fp-in-toc: RS/6000 and PowerPC Options.
+ (line 161)
+* mno-fp-regs: DEC Alpha Options. (line 25)
+* mno-fp-ret-in-387: i386 and x86-64 Options.
+ (line 107)
+* mno-fpu: SPARC Options. (line 25)
+* mno-fused-madd <1>: Xtensa Options. (line 85)
+* mno-fused-madd <2>: MIPS Options. (line 59)
+* mno-fused-madd: RS/6000 and PowerPC Options.
+ (line 259)
+* mno-gnu-as: IA-64 Options. (line 18)
+* mno-gnu-ld: IA-64 Options. (line 23)
+* mno-gotplt: CRIS Options. (line 81)
+* mno-gpopt: MIPS Options. (line 137)
+* mno-half-pic: MIPS Options. (line 195)
+* mno-hardlit: MCore Options. (line 11)
+* mno-ieee-fp: i386 and x86-64 Options.
+ (line 90)
+* mno-impure-text: AMD29K Options. (line 79)
+* mno-int16: PDP-11 Options. (line 44)
+* mno-int32: PDP-11 Options. (line 40)
+* mno-interrupts: AVR Options. (line 39)
+* mno-knuthdiv: MMIX Options. (line 33)
+* mno-leaf-procedures: Intel 960 Options. (line 22)
+* mno-libfuncs: MMIX Options. (line 10)
+* mno-long-calls <1>: V850 Options. (line 10)
+* mno-long-calls <2>: MIPS Options. (line 188)
+* mno-long-calls: ARM Options. (line 191)
+* mno-longcalls: Xtensa Options. (line 133)
+* mno-loop-unsigned: TMS320C3x/C4x Options.
+ (line 95)
+* mno-mac16: Xtensa Options. (line 24)
+* mno-mad: MIPS Options. (line 229)
+* mno-max: DEC Alpha Options. (line 171)
+* mno-memcpy: MIPS Options. (line 152)
+* mno-minmax: Xtensa Options. (line 59)
+* mno-mips-tfile: MIPS Options. (line 158)
+* mno-mips16: MIPS Options. (line 238)
+* mno-mmx: i386 and x86-64 Options.
+ (line 235)
+* mno-mpyi: TMS320C3x/C4x Options.
+ (line 54)
+* mno-mul16: Xtensa Options. (line 34)
+* mno-mul32: Xtensa Options. (line 44)
+* mno-mult-bug: MN10300 Options. (line 13)
+* mno-multiple: RS/6000 and PowerPC Options.
+ (line 227)
+* mno-multm: AMD29K Options. (line 92)
+* mno-mvcle: S/390 and zSeries Options.
+ (line 42)
+* mno-nsa: Xtensa Options. (line 54)
+* mno-ocs-debug-info: M88K Options. (line 34)
+* mno-ocs-frame-position: M88K Options. (line 51)
+* mno-optimize-arg-area: M88K Options. (line 63)
+* mno-parallel-insns: TMS320C3x/C4x Options.
+ (line 116)
+* mno-parallel-mpy: TMS320C3x/C4x Options.
+ (line 121)
+* mno-pic: IA-64 Options. (line 26)
+* mno-power: RS/6000 and PowerPC Options.
+ (line 19)
+* mno-power2: RS/6000 and PowerPC Options.
+ (line 19)
+* mno-powerpc: RS/6000 and PowerPC Options.
+ (line 19)
+* mno-powerpc-gfxopt: RS/6000 and PowerPC Options.
+ (line 19)
+* mno-powerpc-gpopt: RS/6000 and PowerPC Options.
+ (line 19)
+* mno-powerpc64: RS/6000 and PowerPC Options.
+ (line 19)
+* mno-prolog-function: V850 Options. (line 23)
+* mno-prologue-epilogue: CRIS Options. (line 71)
+* mno-prototype: RS/6000 and PowerPC Options.
+ (line 366)
+* mno-push-args: i386 and x86-64 Options.
+ (line 247)
+* mno-register-names: IA-64 Options. (line 40)
+* mno-regnames: RS/6000 and PowerPC Options.
+ (line 466)
+* mno-relax-immediate: MCore Options. (line 22)
+* mno-relocatable: RS/6000 and PowerPC Options.
+ (line 282)
+* mno-relocatable-lib: RS/6000 and PowerPC Options.
+ (line 290)
+* mno-reuse-arg-regs: AMD29K Options. (line 73)
+* mno-rnames: MIPS Options. (line 130)
+* mno-rptb: TMS320C3x/C4x Options.
+ (line 73)
+* mno-rpts: TMS320C3x/C4x Options.
+ (line 82)
+* mno-sched-prolog: ARM Options. (line 40)
+* mno-sdata <1>: IA-64 Options. (line 45)
+* mno-sdata: RS/6000 and PowerPC Options.
+ (line 453)
+* mno-serialize-volatile <1>: Interoperation. (line 197)
+* mno-serialize-volatile <2>: Xtensa Options. (line 101)
+* mno-serialize-volatile: M88K Options. (line 78)
+* mno-sext: Xtensa Options. (line 64)
+* mno-short-load-bytes: ARM Options. (line 119)
+* mno-short-load-words: ARM Options. (line 115)
+* mno-side-effects: CRIS Options. (line 46)
+* mno-slow-bytes: MCore Options. (line 42)
+* mno-small-exec: S/390 and zSeries Options.
+ (line 27)
+* mno-soft-float: DEC Alpha Options. (line 10)
+* mno-space-regs: HPPA Options. (line 49)
+* mno-split: PDP-11 Options. (line 72)
+* mno-split-addresses: MIPS Options. (line 122)
+* mno-sse: i386 and x86-64 Options.
+ (line 235)
+* mno-stack-align: CRIS Options. (line 55)
+* mno-stack-bias: SPARC Options. (line 220)
+* mno-stack-check: AMD29K Options. (line 62)
+* mno-stats: MIPS Options. (line 145)
+* mno-storem-bug: AMD29K Options. (line 67)
+* mno-strict-align <1>: Intel 960 Options. (line 62)
+* mno-strict-align <2>: RS/6000 and PowerPC Options.
+ (line 277)
+* mno-strict-align: M680x0 Options. (line 148)
+* mno-string: RS/6000 and PowerPC Options.
+ (line 238)
+* mno-sum-in-toc: RS/6000 and PowerPC Options.
+ (line 161)
+* mno-svr3-shlib: i386 and x86-64 Options.
+ (line 158)
+* mno-symrename: ARM Options. (line 130)
+* mno-tablejump: AVR Options. (line 47)
+* mno-tail-call: Intel 960 Options. (line 31)
+* mno-target-align: Xtensa Options. (line 120)
+* mno-text-section-literals: Xtensa Options. (line 108)
+* mno-toc: RS/6000 and PowerPC Options.
+ (line 299)
+* mno-toplevel-symbols: MMIX Options. (line 40)
+* mno-unaligned-doubles: SPARC Options. (line 73)
+* mno-underscores: M88K Options. (line 28)
+* mno-uninit-const-in-rodata: MIPS Options. (line 217)
+* mno-update: RS/6000 and PowerPC Options.
+ (line 249)
+* mno-volatile-asm-stop: IA-64 Options. (line 32)
+* mno-wide-bitfields: MCore Options. (line 27)
+* mno-xl-call: RS/6000 and PowerPC Options.
+ (line 196)
+* mno-zero-extend: MMIX Options. (line 27)
+* mnoargcount: Convex Options. (line 40)
+* mnobitfield <1>: NS32K Options. (line 54)
+* mnobitfield: M680x0 Options. (line 96)
+* mnohc-struct-return: RT Options. (line 43)
+* mnohimem: NS32K Options. (line 111)
+* mnomacsave: SH Options. (line 61)
+* mnomulti-add: NS32K Options. (line 46)
+* mnop-fun-dllimport: ARM Options. (line 216)
+* mnoregparam: NS32K Options. (line 90)
+* mnormal: AMD29K Options. (line 31)
+* mnosb: NS32K Options. (line 98)
+* mnsa: Xtensa Options. (line 54)
+* mnumerics: Intel 960 Options. (line 16)
+* mocs-debug-info: M88K Options. (line 34)
+* mocs-frame-position: M88K Options. (line 43)
+* mold-align: Intel 960 Options. (line 65)
+* mold-mnemonics: RS/6000 and PowerPC Options.
+ (line 67)
+* momit-leaf-frame-pointer: i386 and x86-64 Options.
+ (line 282)
+* monchip: D30V Options. (line 17)
+* moptimize-arg-area: M88K Options. (line 58)
+* MP: Preprocessor Options.
+ (line 173)
+* mpa-risc-1-0: HPPA Options. (line 23)
+* mpa-risc-1-1: HPPA Options. (line 23)
+* mpa-risc-2-0: HPPA Options. (line 23)
+* mpadstruct: SH Options. (line 71)
+* mparallel-insns: TMS320C3x/C4x Options.
+ (line 116)
+* mparallel-mpy: TMS320C3x/C4x Options.
+ (line 121)
+* mparanoid: TMS320C3x/C4x Options.
+ (line 46)
+* mpcrel: M680x0 Options. (line 140)
+* mpdebug: CRIS Options. (line 35)
+* mpe: RS/6000 and PowerPC Options.
+ (line 210)
+* mpentium: i386 and x86-64 Options.
+ (line 33)
+* mpentiumpro: i386 and x86-64 Options.
+ (line 33)
+* mpic-register: ARM Options. (line 225)
+* mpoke-function-name: ARM Options. (line 229)
+* mportable-runtime: HPPA Options. (line 68)
+* mpower: RS/6000 and PowerPC Options.
+ (line 19)
+* mpower2: RS/6000 and PowerPC Options.
+ (line 19)
+* mpowerpc: RS/6000 and PowerPC Options.
+ (line 19)
+* mpowerpc-gfxopt: RS/6000 and PowerPC Options.
+ (line 19)
+* mpowerpc-gpopt: RS/6000 and PowerPC Options.
+ (line 19)
+* mpowerpc64: RS/6000 and PowerPC Options.
+ (line 19)
+* mprefergot: SH Options. (line 78)
+* mpreferred-stack-boundary: i386 and x86-64 Options.
+ (line 198)
+* mprolog-function: V850 Options. (line 23)
+* mprologue-epilogue: CRIS Options. (line 71)
+* mprototype: RS/6000 and PowerPC Options.
+ (line 366)
+* mpush-args: i386 and x86-64 Options.
+ (line 247)
+* MQ: Preprocessor Options.
+ (line 199)
+* mregister-names: IA-64 Options. (line 40)
+* mregnames: RS/6000 and PowerPC Options.
+ (line 466)
+* mregparam: NS32K Options. (line 82)
+* mregparm <1>: TMS320C3x/C4x Options.
+ (line 110)
+* mregparm: i386 and x86-64 Options.
+ (line 187)
+* mrelax <1>: SH Options. (line 47)
+* mrelax <2>: H8/300 Options. (line 9)
+* mrelax <3>: MN10300 Options. (line 27)
+* mrelax: MN10200 Options. (line 8)
+* mrelax-immediate: MCore Options. (line 22)
+* mrelocatable: RS/6000 and PowerPC Options.
+ (line 282)
+* mrelocatable-lib: RS/6000 and PowerPC Options.
+ (line 290)
+* mreuse-arg-regs: AMD29K Options. (line 73)
+* mrnames: MIPS Options. (line 130)
+* mrodata: ARC Options. (line 30)
+* mrptb: TMS320C3x/C4x Options.
+ (line 73)
+* mrpts: TMS320C3x/C4x Options.
+ (line 82)
+* mrtd <1>: Function Attributes. (line 308)
+* mrtd <2>: NS32K Options. (line 63)
+* mrtd <3>: i386 and x86-64 Options.
+ (line 163)
+* mrtd: M680x0 Options. (line 105)
+* ms: H8/300 Options. (line 17)
+* ms2600: H8/300 Options. (line 20)
+* msa: Intel 960 Options. (line 9)
+* msb <1>: NS32K Options. (line 94)
+* msb: Intel 960 Options. (line 9)
+* mschedule: HPPA Options. (line 75)
+* msda: V850 Options. (line 40)
+* msdata <1>: IA-64 Options. (line 45)
+* msdata: RS/6000 and PowerPC Options.
+ (line 440)
+* msdata-data: RS/6000 and PowerPC Options.
+ (line 445)
+* msdata=default: RS/6000 and PowerPC Options.
+ (line 440)
+* msdata=eabi: RS/6000 and PowerPC Options.
+ (line 420)
+* msdata=none <1>: RS/6000 and PowerPC Options.
+ (line 453)
+* msdata=none: M32R/D Options. (line 37)
+* msdata=sdata: M32R/D Options. (line 46)
+* msdata=sysv: RS/6000 and PowerPC Options.
+ (line 431)
+* msdata=use: M32R/D Options. (line 50)
+* mserialize-volatile <1>: Xtensa Options. (line 101)
+* mserialize-volatile: M88K Options. (line 77)
+* msext: Xtensa Options. (line 64)
+* mshort <1>: M68hc1x Options. (line 26)
+* mshort: M680x0 Options. (line 93)
+* mshort-data: M88K Options. (line 68)
+* mshort-load-bytes: ARM Options. (line 115)
+* mshort-load-words: ARM Options. (line 119)
+* msim <1>: Xstormy16 Options. (line 9)
+* msim: RS/6000 and PowerPC Options.
+ (line 376)
+* msingle-float: MIPS Options. (line 222)
+* msingle-pic-base: ARM Options. (line 219)
+* msize: AVR Options. (line 32)
+* mslow-bytes: MCore Options. (line 42)
+* msmall <1>: TMS320C3x/C4x Options.
+ (line 19)
+* msmall: AMD29K Options. (line 25)
+* msmall-data: DEC Alpha Options. (line 195)
+* msmall-exec: S/390 and zSeries Options.
+ (line 27)
+* msmall-memory: TMS320C3x/C4x Options.
+ (line 19)
+* msoft-float <1>: Xtensa Options. (line 76)
+* msoft-float <2>: PDP-11 Options. (line 13)
+* msoft-float <3>: S/390 and zSeries Options.
+ (line 11)
+* msoft-float <4>: NS32K Options. (line 50)
+* msoft-float <5>: DEC Alpha Options. (line 10)
+* msoft-float <6>: Intel 960 Options. (line 16)
+* msoft-float <7>: HPPA Options. (line 87)
+* msoft-float <8>: i386 and x86-64 Options.
+ (line 95)
+* msoft-float <9>: MIPS Options. (line 169)
+* msoft-float <10>: RS/6000 and PowerPC Options.
+ (line 221)
+* msoft-float <11>: ARM Options. (line 53)
+* msoft-float <12>: AMD29K Options. (line 84)
+* msoft-float <13>: SPARC Options. (line 25)
+* msoft-float: M680x0 Options. (line 83)
+* msoft-quad-float: SPARC Options. (line 45)
+* msoft-reg-count: M68hc1x Options. (line 29)
+* mspace <1>: V850 Options. (line 30)
+* mspace: SH Options. (line 75)
+* msparclite: SPARC Options. (line 96)
+* msplit: PDP-11 Options. (line 69)
+* msplit-addresses: MIPS Options. (line 122)
+* msse: i386 and x86-64 Options.
+ (line 235)
+* mstack-align: CRIS Options. (line 55)
+* mstack-bias: SPARC Options. (line 220)
+* mstack-check: AMD29K Options. (line 62)
+* mstats: MIPS Options. (line 145)
+* mstorem-bug: AMD29K Options. (line 67)
+* mstrict-align <1>: Intel 960 Options. (line 62)
+* mstrict-align <2>: RS/6000 and PowerPC Options.
+ (line 277)
+* mstrict-align: M680x0 Options. (line 148)
+* mstring: RS/6000 and PowerPC Options.
+ (line 238)
+* mstructure-size-boundary: ARM Options. (line 174)
+* msupersparc: SPARC Options. (line 115)
+* msvr3: M88K Options. (line 103)
+* msvr3-shlib: i386 and x86-64 Options.
+ (line 158)
+* msvr4: M88K Options. (line 103)
+* msvr4-struct-return: RS/6000 and PowerPC Options.
+ (line 353)
+* MT: Preprocessor Options.
+ (line 185)
+* mtail-call: Intel 960 Options. (line 31)
+* mtarget-align: Xtensa Options. (line 120)
+* mtda: V850 Options. (line 34)
+* mtext: ARC Options. (line 30)
+* mtext-section-literals: Xtensa Options. (line 108)
+* mthreads: i386 and x86-64 Options.
+ (line 262)
+* mthumb: ARM Options. (line 250)
+* mthumb-interwork: ARM Options. (line 33)
+* mti: TMS320C3x/C4x Options.
+ (line 103)
+* mtiny-stack: AVR Options. (line 50)
+* mtoc: RS/6000 and PowerPC Options.
+ (line 299)
+* mtoplevel-symbols: MMIX Options. (line 40)
+* mtpcs-frame: ARM Options. (line 254)
+* mtpcs-leaf-frame: ARM Options. (line 260)
+* mtrap-large-shift: M88K Options. (line 169)
+* mtrap-precision: DEC Alpha Options. (line 109)
+* mtune <1>: CRIS Options. (line 16)
+* mtune <2>: DEC Alpha Options. (line 253)
+* mtune <3>: MIPS Options. (line 17)
+* mtune <4>: RS/6000 and PowerPC Options.
+ (line 142)
+* mtune <5>: ARM Options. (line 149)
+* mtune: SPARC Options. (line 151)
+* munaligned-doubles: SPARC Options. (line 73)
+* muninit-const-in-rodata: MIPS Options. (line 217)
+* munix: VAX Options. (line 9)
+* munix-asm: PDP-11 Options. (line 75)
+* mupdate: RS/6000 and PowerPC Options.
+ (line 249)
+* muse-div-instruction: M88K Options. (line 141)
+* muser-registers: AMD29K Options. (line 57)
+* musermode: SH Options. (line 83)
+* mv8: SPARC Options. (line 96)
+* mv850: V850 Options. (line 49)
+* mversion-03.00: M88K Options. (line 119)
+* mvms-return-codes: DEC Alpha/VMS Options.
+ (line 9)
+* mvolatile-asm-stop: IA-64 Options. (line 32)
+* mvolatile-cache: Convex Options. (line 43)
+* mvolatile-nocache: Convex Options. (line 46)
+* mvxworks: RS/6000 and PowerPC Options.
+ (line 397)
+* mwarn-passed-structs: M88K Options. (line 175)
+* mwide-bitfields: MCore Options. (line 27)
+* mwords-little-endian: ARM Options. (line 75)
+* mxl-call: RS/6000 and PowerPC Options.
+ (line 196)
+* mxopen: ARM Options. (line 126)
+* myellowknife: RS/6000 and PowerPC Options.
+ (line 392)
+* mzda: V850 Options. (line 45)
+* mzero-extend: MMIX Options. (line 27)
+* no-crt0: MIPS Options. (line 272)
+* no-integrated-cpp: C Dialect Options. (line 178)
+* no-red-zone: i386 and x86-64 Options.
+ (line 300)
+* noasmopt: Interoperation. (line 261)
+* nocpp: MIPS Options. (line 263)
+* nodefaultlibs: Link Options. (line 62)
+* nostartfiles: Link Options. (line 57)
+* nostdinc: Preprocessor Options.
+ (line 287)
+* nostdinc++ <1>: Preprocessor Options.
+ (line 292)
+* nostdinc++: C++ Dialect Options. (line 206)
+* nostdlib: Link Options. (line 72)
+* o: Preprocessor Options.
+ (line 61)
+* O: Optimize Options. (line 10)
+* o: Overall Options. (line 146)
+* O0: Optimize Options. (line 47)
+* O1: Optimize Options. (line 10)
+* O2: Optimize Options. (line 26)
+* O3: Optimize Options. (line 42)
+* Os: Optimize Options. (line 50)
+* P: Preprocessor Options.
+ (line 413)
+* p: Debugging Options. (line 119)
+* param: Optimize Options. (line 635)
+* pass-exit-codes: Overall Options. (line 105)
+* pedantic <1>: Warnings and Errors. (line 25)
+* pedantic <2>: Alternate Keywords. (line 33)
+* pedantic <3>: C Extensions. (line 6)
+* pedantic <4>: Preprocessor Options.
+ (line 113)
+* pedantic <5>: Warning Options. (line 26)
+* pedantic: Standards. (line 13)
+* pedantic-errors <1>: Warnings and Errors. (line 25)
+* pedantic-errors <2>: Non-bugs. (line 203)
+* pedantic-errors <3>: Actual Bugs. (line 18)
+* pedantic-errors <4>: Preprocessor Options.
+ (line 118)
+* pedantic-errors <5>: Warning Options. (line 68)
+* pedantic-errors: Standards. (line 13)
+* pg: Debugging Options. (line 125)
+* pipe: Overall Options. (line 171)
+* print-file-name: Debugging Options. (line 438)
+* print-libgcc-file-name: Debugging Options. (line 459)
+* print-multi-directory: Debugging Options. (line 444)
+* print-multi-lib: Debugging Options. (line 449)
+* print-prog-name: Debugging Options. (line 456)
+* print-search-dirs: Debugging Options. (line 467)
+* pthread: RS/6000 and PowerPC Options.
+ (line 471)
+* Q: Debugging Options. (line 131)
+* Qn: System V Options. (line 18)
+* Qy: System V Options. (line 14)
+* remap: Preprocessor Options.
+ (line 453)
+* s: Link Options. (line 94)
+* S <1>: Link Options. (line 20)
+* S: Overall Options. (line 129)
+* save-temps: Debugging Options. (line 416)
+* shared: Link Options. (line 103)
+* shared-libgcc: Link Options. (line 111)
+* sim: CRIS Options. (line 103)
+* sim2: CRIS Options. (line 109)
+* specs: Directory Options. (line 98)
+* static: Link Options. (line 98)
+* static-libgcc: Link Options. (line 111)
+* std <1>: Non-bugs. (line 102)
+* std <2>: Other Builtins. (line 22)
+* std <3>: C Dialect Options. (line 46)
+* std: Standards. (line 13)
+* std=: Preprocessor Options.
+ (line 246)
+* symbolic: Link Options. (line 146)
+* target-help <1>: Preprocessor Options.
+ (line 464)
+* target-help: Overall Options. (line 186)
+* time: Debugging Options. (line 424)
+* traditional <1>: Non-bugs. (line 102)
+* traditional <2>: Incompatibilities. (line 6)
+* traditional <3>: Preprocessor Options.
+ (line 436)
+* traditional <4>: C Dialect Options. (line 187)
+* traditional: Standards. (line 50)
+* traditional-cpp: C Dialect Options. (line 238)
+* trigraphs <1>: Preprocessor Options.
+ (line 440)
+* trigraphs: C Dialect Options. (line 174)
+* u: Link Options. (line 168)
+* U: Preprocessor Options.
+ (line 43)
+* undef: Preprocessor Options.
+ (line 47)
+* V: Target Options. (line 30)
+* v <1>: Preprocessor Options.
+ (line 468)
+* v: Overall Options. (line 160)
+* version <1>: Preprocessor Options.
+ (line 478)
+* version: Overall Options. (line 190)
+* W: Incompatibilities. (line 72)
+* w: Preprocessor Options.
+ (line 109)
+* W: Warning Options. (line 434)
+* w: Warning Options. (line 72)
+* Wa: Assembler Options. (line 9)
+* Wabi: C++ Dialect Options. (line 220)
+* Waggregate-return: Warning Options. (line 640)
+* Wall <1>: Standard Libraries. (line 6)
+* Wall <2>: Preprocessor Options.
+ (line 67)
+* Wall: Warning Options. (line 397)
+* Wbad-function-cast: Warning Options. (line 595)
+* Wcast-align: Warning Options. (line 604)
+* Wcast-qual: Warning Options. (line 599)
+* Wchar-subscripts: Warning Options. (line 78)
+* Wcomment <1>: Preprocessor Options.
+ (line 74)
+* Wcomment: Warning Options. (line 83)
+* Wcomments: Preprocessor Options.
+ (line 74)
+* Wconversion <1>: Protoize Caveats. (line 31)
+* Wconversion: Warning Options. (line 621)
+* Wctor-dtor-privacy: C++ Dialect Options. (line 262)
+* Wdisabled-optimization: Warning Options. (line 751)
+* Wdiv-by-zero: Warning Options. (line 403)
+* Weffc++: C++ Dialect Options. (line 288)
+* Werror <1>: Preprocessor Options.
+ (line 99)
+* Werror: Warning Options. (line 760)
+* Werror-implicit-function-declaration: Warning Options. (line 157)
+* Wfloat-equal: Warning Options. (line 495)
+* Wformat <1>: Function Attributes. (line 123)
+* Wformat: Warning Options. (line 87)
+* Wformat-nonliteral <1>: Function Attributes. (line 168)
+* Wformat-nonliteral: Warning Options. (line 132)
+* Wformat-security: Warning Options. (line 137)
+* Wformat=2: Warning Options. (line 148)
+* Wimplicit: Warning Options. (line 161)
+* Wimplicit-function-declaration: Warning Options. (line 157)
+* Wimplicit-int: Warning Options. (line 153)
+* Wimport: Preprocessor Options.
+ (line 91)
+* Winline <1>: Inline. (line 35)
+* Winline: Warning Options. (line 741)
+* Wl: Link Options. (line 164)
+* Wlarger-than: Warning Options. (line 586)
+* Wlong-long: Warning Options. (line 745)
+* Wmain: Warning Options. (line 164)
+* Wmissing-braces: Warning Options. (line 169)
+* Wmissing-declarations: Warning Options. (line 657)
+* Wmissing-format-attribute: Warning Options. (line 671)
+* Wmissing-noreturn: Warning Options. (line 663)
+* Wmissing-prototypes: Warning Options. (line 651)
+* Wmultichar: Warning Options. (line 409)
+* Wnested-externs: Warning Options. (line 716)
+* Wno-deprecated: C++ Dialect Options. (line 318)
+* Wno-deprecated-declarations: Warning Options. (line 681)
+* Wno-div-by-zero: Warning Options. (line 403)
+* Wno-format-extra-args: Warning Options. (line 118)
+* Wno-format-y2k: Warning Options. (line 114)
+* Wno-import: Warning Options. (line 75)
+* Wno-long-long: Warning Options. (line 745)
+* Wno-multichar: Warning Options. (line 409)
+* Wno-non-template-friend: C++ Dialect Options. (line 322)
+* Wno-pmf-conversions <1>: Bound member functions.
+ (line 35)
+* Wno-pmf-conversions: C++ Dialect Options. (line 363)
+* Wno-protocol: Objective-C Dialect Options.
+ (line 38)
+* Wnon-virtual-dtor: C++ Dialect Options. (line 267)
+* Wold-style-cast: C++ Dialect Options. (line 338)
+* Woverloaded-virtual: C++ Dialect Options. (line 344)
+* Wp: Preprocessor Options.
+ (line 13)
+* Wpacked: Warning Options. (line 687)
+* Wpadded: Warning Options. (line 704)
+* Wparentheses: Warning Options. (line 177)
+* Wpointer-arith <1>: Pointer Arith. (line 13)
+* Wpointer-arith: Warning Options. (line 589)
+* Wredundant-decls: Warning Options. (line 711)
+* Wreorder <1>: Warning Options. (line 386)
+* Wreorder: C++ Dialect Options. (line 272)
+* Wreturn-type: Warning Options. (line 262)
+* Wselector: Objective-C Dialect Options.
+ (line 42)
+* Wsequence-point: Warning Options. (line 215)
+* Wshadow: Warning Options. (line 581)
+* Wsign-compare: Warning Options. (line 634)
+* Wsign-promo: C++ Dialect Options. (line 367)
+* Wstrict-prototypes: Warning Options. (line 645)
+* Wswitch: Warning Options. (line 272)
+* Wsynth: C++ Dialect Options. (line 374)
+* Wsystem-headers <1>: Preprocessor Options.
+ (line 103)
+* Wsystem-headers: Warning Options. (line 416)
+* Wtraditional <1>: Preprocessor Options.
+ (line 85)
+* Wtraditional: Warning Options. (line 510)
+* Wtrigraphs <1>: Preprocessor Options.
+ (line 79)
+* Wtrigraphs: Warning Options. (line 279)
+* Wundef <1>: Preprocessor Options.
+ (line 94)
+* Wundef: Warning Options. (line 578)
+* Wuninitialized: Warning Options. (line 321)
+* Wunknown-pragmas: Warning Options. (line 390)
+* Wunreachable-code: Warning Options. (line 719)
+* Wunused: Warning Options. (line 314)
+* Wunused-function: Warning Options. (line 284)
+* Wunused-label: Warning Options. (line 288)
+* Wunused-parameter: Warning Options. (line 294)
+* Wunused-value: Warning Options. (line 308)
+* Wunused-variable: Warning Options. (line 301)
+* Wwrite-strings: Warning Options. (line 610)
+* x <1>: Preprocessor Options.
+ (line 230)
+* x: Overall Options. (line 83)
+* Xlinker: Link Options. (line 152)
+* Ym: System V Options. (line 26)
+* YP: System V Options. (line 22)
\1f
-File: gcc.info, Node: Optimize Options, Next: Preprocessor Options, Prev: Debugging Options, Up: Invoking GCC
-
-Options That Control Optimization
-=================================
-
- These options control various sorts of optimizations:
-
-`-O'
-`-O1'
- Optimize. Optimizing compilation takes somewhat more time, and a
- lot more memory for a large function.
-
- Without `-O', the compiler's goal is to reduce the cost of
- compilation and to make debugging produce the expected results.
- Statements are independent: if you stop the program with a
- breakpoint between statements, you can then assign a new value to
- any variable or change the program counter to any other statement
- in the function and get exactly the results you would expect from
- the source code.
-
- With `-O', the compiler tries to reduce code size and execution
- time, without performing any optimizations that take a great deal
- of compilation time.
-
-`-O2'
- Optimize even more. GCC performs nearly all supported
- optimizations that do not involve a space-speed tradeoff. The
- compiler does not perform loop unrolling or function inlining when
- you specify `-O2'. As compared to `-O', this option increases
- both compilation time and the performance of the generated code.
-
- `-O2' turns on all optional optimizations except for loop
- unrolling, function inlining, and register renaming. It also
- turns on the `-fforce-mem' option on all machines and frame
- pointer elimination on machines where doing so does not interfere
- with debugging.
-
- Please note the warning under `-fgcse' about invoking `-O2' on
- programs that use computed gotos.
-
-`-O3'
- Optimize yet more. `-O3' turns on all optimizations specified by
- `-O2' and also turns on the `-finline-functions' and
- `-frename-registers' options.
-
-`-O0'
- Do not optimize.
-
-`-Os'
- Optimize for size. `-Os' enables all `-O2' optimizations that do
- not typically increase code size. It also performs further
- optimizations designed to reduce code size.
-
- If you use multiple `-O' options, with or without level numbers,
- the last such option is the one that is effective.
-
- Options of the form `-fFLAG' specify machine-independent flags.
-Most flags have both positive and negative forms; the negative form of
-`-ffoo' would be `-fno-foo'. In the table below, only one of the forms
-is listed--the one which is not the default. You can figure out the
-other form by either removing `no-' or adding it.
-
-`-ffloat-store'
- Do not store floating point variables in registers, and inhibit
- other options that might change whether a floating point value is
- taken from a register or memory.
-
- This option prevents undesirable excess precision on machines such
- as the 68000 where the floating registers (of the 68881) keep more
- precision than a `double' is supposed to have. Similarly for the
- x86 architecture. For most programs, the excess precision does
- only good, but a few programs rely on the precise definition of
- IEEE floating point. Use `-ffloat-store' for such programs, after
- modifying them to store all pertinent intermediate computations
- into variables.
-
-`-fno-default-inline'
- Do not make member functions inline by default merely because they
- are defined inside the class scope (C++ only). Otherwise, when
- you specify `-O', member functions defined inside class scope are
- compiled inline by default; i.e., you don't need to add `inline'
- in front of the member function name.
-
-`-fno-defer-pop'
- Always pop the arguments to each function call as soon as that
- function returns. For machines which must pop arguments after a
- function call, the compiler normally lets arguments accumulate on
- the stack for several function calls and pops them all at once.
-
-`-fforce-mem'
- Force memory operands to be copied into registers before doing
- arithmetic on them. This produces better code by making all memory
- references potential common subexpressions. When they are not
- common subexpressions, instruction combination should eliminate
- the separate register-load. The `-O2' option turns on this option.
-
-`-fforce-addr'
- Force memory address constants to be copied into registers before
- doing arithmetic on them. This may produce better code just as
- `-fforce-mem' may.
-
-`-fomit-frame-pointer'
- Don't keep the frame pointer in a register for functions that
- don't need one. This avoids the instructions to save, set up and
- restore frame pointers; it also makes an extra register available
- in many functions. *It also makes debugging impossible on some
- machines.*
-
- On some machines, such as the VAX, this flag has no effect, because
- the standard calling sequence automatically handles the frame
- pointer and nothing is saved by pretending it doesn't exist. The
- machine-description macro `FRAME_POINTER_REQUIRED' controls
- whether a target machine supports this flag. *Note Register
- Usage: (gccint)Registers.
-
-`-foptimize-sibling-calls'
- Optimize sibling and tail recursive calls.
-
-`-ftrapv'
- This option generates traps for signed overflow on addition,
- subtraction, multiplication operations.
-
-`-fno-inline'
- Don't pay attention to the `inline' keyword. Normally this option
- is used to keep the compiler from expanding any functions inline.
- Note that if you are not optimizing, no functions can be expanded
- inline.
-
-`-finline-functions'
- Integrate all simple functions into their callers. The compiler
- heuristically decides which functions are simple enough to be worth
- integrating in this way.
-
- If all calls to a given function are integrated, and the function
- is declared `static', then the function is normally not output as
- assembler code in its own right.
-
-`-finline-limit=N'
- By default, gcc limits the size of functions that can be inlined.
- This flag allows the control of this limit for functions that are
- explicitly marked as inline (ie marked with the inline keyword or
- defined within the class definition in c++). N is the size of
- functions that can be inlined in number of pseudo instructions
- (not counting parameter handling). The default value of N is 600.
- Increasing this value can result in more inlined code at the cost
- of compilation time and memory consumption. Decreasing usually
- makes the compilation faster and less code will be inlined (which
- presumably means slower programs). This option is particularly
- useful for programs that use inlining heavily such as those based
- on recursive templates with C++.
-
- _Note:_ pseudo instruction represents, in this particular context,
- an abstract measurement of function's size. In no way, it
- represents a count of assembly instructions and as such its exact
- meaning might change from one release to an another.
-
-`-fkeep-inline-functions'
- Even if all calls to a given function are integrated, and the
- function is declared `static', nevertheless output a separate
- run-time callable version of the function. This switch does not
- affect `extern inline' functions.
-
-`-fkeep-static-consts'
- Emit variables declared `static const' when optimization isn't
- turned on, even if the variables aren't referenced.
-
- GCC enables this option by default. If you want to force the
- compiler to check if the variable was referenced, regardless of
- whether or not optimization is turned on, use the
- `-fno-keep-static-consts' option.
-
-`-fmerge-constants'
- Attempt to merge identical constants (string constants and
- floating point constants) accross compilation units.
-
- This option is default for optimized compilation if assembler and
- linker support it. Use `-fno-merge-constants' to inhibit this
- behavior.
-
-`-fmerge-all-constants'
- Attempt to merge identical constants and identical variables.
-
- This option implies `-fmerge-constants'. In addition to
- `-fmerge-constants' this considers e.g. even constant initialized
- arrays or initialized constant variables with integral or floating
- point types. Languages like C or C++ require each non-automatic
- variable to have distinct location, so using this option will
- result in non-conforming behavior.
-
-`-fno-branch-count-reg'
- Do not use "decrement and branch" instructions on a count register,
- but instead generate a sequence of instructions that decrement a
- register, compare it against zero, then branch based upon the
- result. This option is only meaningful on architectures that
- support such instructions, which include x86, PowerPC, IA-64 and
- S/390.
-
-`-fno-function-cse'
- Do not put function addresses in registers; make each instruction
- that calls a constant function contain the function's address
- explicitly.
-
- This option results in less efficient code, but some strange hacks
- that alter the assembler output may be confused by the
- optimizations performed when this option is not used.
-
-`-ffast-math'
- Sets `-fno-math-errno', `-funsafe-math-optimizations', and
- `-fno-trapping-math'.
-
- This option causes the preprocessor macro `__FAST_MATH__' to be
- defined.
-
- This option should never be turned on by any `-O' option since it
- can result in incorrect output for programs which depend on an
- exact implementation of IEEE or ISO rules/specifications for math
- functions.
-
-`-fno-math-errno'
- Do not set ERRNO after calling math functions that are executed
- with a single instruction, e.g., sqrt. A program that relies on
- IEEE exceptions for math error handling may want to use this flag
- for speed while maintaining IEEE arithmetic compatibility.
-
- This option should never be turned on by any `-O' option since it
- can result in incorrect output for programs which depend on an
- exact implementation of IEEE or ISO rules/specifications for math
- functions.
-
- The default is `-fmath-errno'.
-
-`-funsafe-math-optimizations'
- Allow optimizations for floating-point arithmetic that (a) assume
- that arguments and results are valid and (b) may violate IEEE or
- ANSI standards. When used at link-time, it may include libraries
- or startup files that change the default FPU control word or other
- similar optimizations.
-
- This option should never be turned on by any `-O' option since it
- can result in incorrect output for programs which depend on an
- exact implementation of IEEE or ISO rules/specifications for math
- functions.
-
- The default is `-fno-unsafe-math-optimizations'.
-
-`-fno-trapping-math'
- Compile code assuming that floating-point operations cannot
- generate user-visible traps. Setting this option may allow faster
- code if one relies on "non-stop" IEEE arithmetic, for example.
-
- This option should never be turned on by any `-O' option since it
- can result in incorrect output for programs which depend on an
- exact implementation of IEEE or ISO rules/specifications for math
- functions.
-
- The default is `-ftrapping-math'.
-
-`-fbounds-check'
- For front-ends that support it, generate additional code to check
- that indices used to access arrays are within the declared range.
- This is currenly only supported by the Java and Fortran 77
- front-ends, where this option defaults to true and false
- respectively.
-
-
- The following options control specific optimizations. The `-O2'
-option turns on all of these optimizations except `-funroll-loops' and
-`-funroll-all-loops'. On most machines, the `-O' option turns on the
-`-fthread-jumps' and `-fdelayed-branch' options, but specific machines
-may handle it differently.
-
- You can use the following flags in the rare cases when "fine-tuning"
-of optimizations to be performed is desired.
-
- Not all of the optimizations performed by GCC have `-f' options to
-control them.
-
-`-fstrength-reduce'
- Perform the optimizations of loop strength reduction and
- elimination of iteration variables.
-
-`-fthread-jumps'
- Perform optimizations where we check to see if a jump branches to a
- location where another comparison subsumed by the first is found.
- If so, the first branch is redirected to either the destination of
- the second branch or a point immediately following it, depending
- on whether the condition is known to be true or false.
-
-`-fcse-follow-jumps'
- In common subexpression elimination, scan through jump instructions
- when the target of the jump is not reached by any other path. For
- example, when CSE encounters an `if' statement with an `else'
- clause, CSE will follow the jump when the condition tested is
- false.
-
-`-fcse-skip-blocks'
- This is similar to `-fcse-follow-jumps', but causes CSE to follow
- jumps which conditionally skip over blocks. When CSE encounters a
- simple `if' statement with no else clause, `-fcse-skip-blocks'
- causes CSE to follow the jump around the body of the `if'.
-
-`-frerun-cse-after-loop'
- Re-run common subexpression elimination after loop optimizations
- has been performed.
-
-`-frerun-loop-opt'
- Run the loop optimizer twice.
-
-`-fgcse'
- Perform a global common subexpression elimination pass. This pass
- also performs global constant and copy propagation.
-
- _Note:_ When compiling a program using computed gotos, a GCC
- extension, you may get better runtime performance if you disable
- the global common subexpression elmination pass by adding
- `-fno-gcse' to the command line.
-
-`-fgcse-lm'
- When `-fgcse-lm' is enabled, global common subexpression
- elimination will attempt to move loads which are only killed by
- stores into themselves. This allows a loop containing a
- load/store sequence to be changed to a load outside the loop, and
- a copy/store within the loop.
-
-`-fgcse-sm'
- When `-fgcse-sm' is enabled, A store motion pass is run after
- global common subexpression elimination. This pass will attempt
- to move stores out of loops. When used in conjunction with
- `-fgcse-lm', loops containing a load/store sequence can be changed
- to a load before the loop and a store after the loop.
-
-`-fdelete-null-pointer-checks'
- Use global dataflow analysis to identify and eliminate useless
- checks for null pointers. The compiler assumes that dereferencing
- a null pointer would have halted the program. If a pointer is
- checked after it has already been dereferenced, it cannot be null.
-
- In some environments, this assumption is not true, and programs can
- safely dereference null pointers. Use
- `-fno-delete-null-pointer-checks' to disable this optimization for
- programs which depend on that behavior.
-
-`-fexpensive-optimizations'
- Perform a number of minor optimizations that are relatively
- expensive.
-
-`-foptimize-register-move'
-`-fregmove'
- Attempt to reassign register numbers in move instructions and as
- operands of other simple instructions in order to maximize the
- amount of register tying. This is especially helpful on machines
- with two-operand instructions. GCC enables this optimization by
- default with `-O2' or higher.
-
- Note `-fregmove' and `-foptimize-register-move' are the same
- optimization.
-
-`-fdelayed-branch'
- If supported for the target machine, attempt to reorder
- instructions to exploit instruction slots available after delayed
- branch instructions.
-
-`-fschedule-insns'
- If supported for the target machine, attempt to reorder
- instructions to eliminate execution stalls due to required data
- being unavailable. This helps machines that have slow floating
- point or memory load instructions by allowing other instructions
- to be issued until the result of the load or floating point
- instruction is required.
-
-`-fschedule-insns2'
- Similar to `-fschedule-insns', but requests an additional pass of
- instruction scheduling after register allocation has been done.
- This is especially useful on machines with a relatively small
- number of registers and where memory load instructions take more
- than one cycle.
-
-`-fno-sched-interblock'
- Don't schedule instructions across basic blocks. This is normally
- enabled by default when scheduling before register allocation, i.e.
- with `-fschedule-insns' or at `-O2' or higher.
-
-`-fno-sched-spec'
- Don't allow speculative motion of non-load instructions. This is
- normally enabled by default when scheduling before register
- allocation, i.e. with `-fschedule-insns' or at `-O2' or higher.
-
-`-fsched-spec-load'
- Allow speculative motion of some load instructions. This only
- makes sense when scheduling before register allocation, i.e. with
- `-fschedule-insns' or at `-O2' or higher.
-
-`-fsched-spec-load-dangerous'
- Allow speculative motion of more load instructions. This only
- makes sense when scheduling before register allocation, i.e. with
- `-fschedule-insns' or at `-O2' or higher.
-
-`-ffunction-sections'
-`-fdata-sections'
- Place each function or data item into its own section in the output
- file if the target supports arbitrary sections. The name of the
- function or the name of the data item determines the section's name
- in the output file.
-
- Use these options on systems where the linker can perform
- optimizations to improve locality of reference in the instruction
- space. HPPA processors running HP-UX and Sparc processors running
- Solaris 2 have linkers with such optimizations. Other systems
- using the ELF object format as well as AIX may have these
- optimizations in the future.
-
- Only use these options when there are significant benefits from
- doing so. When you specify these options, the assembler and
- linker will create larger object and executable files and will
- also be slower. You will not be able to use `gprof' on all
- systems if you specify this option and you may have problems with
- debugging if you specify both this option and `-g'.
-
-`-fcaller-saves'
- Enable values to be allocated in registers that will be clobbered
- by function calls, by emitting extra instructions to save and
- restore the registers around such calls. Such allocation is done
- only when it seems to result in better code than would otherwise
- be produced.
-
- This option is always enabled by default on certain machines,
- usually those which have no call-preserved registers to use
- instead.
-
- For all machines, optimization level 2 and higher enables this
- flag by default.
-
-`-funroll-loops'
- Unroll loops whose number of iterations can be determined at
- compile time or upon entry to the loop. `-funroll-loops' implies
- both `-fstrength-reduce' and `-frerun-cse-after-loop'. This
- option makes code larger, and may or may not make it run faster.
-
-`-funroll-all-loops'
- Unroll all loops, even if their number of iterations is uncertain
- when the loop is entered. This usually makes programs run more
- slowly. `-funroll-all-loops' implies the same options as
- `-funroll-loops',
-
-`-fprefetch-loop-arrays'
- If supported by the target machine, generate instructions to
- prefetch memory to improve the performance of loops that access
- large arrays.
-
-`-fmove-all-movables'
- Forces all invariant computations in loops to be moved outside the
- loop.
-
-`-freduce-all-givs'
- Forces all general-induction variables in loops to be
- strength-reduced.
-
- _Note:_ When compiling programs written in Fortran,
- `-fmove-all-movables' and `-freduce-all-givs' are enabled by
- default when you use the optimizer.
-
- These options may generate better or worse code; results are highly
- dependent on the structure of loops within the source code.
-
- These two options are intended to be removed someday, once they
- have helped determine the efficacy of various approaches to
- improving loop optimizations.
-
- Please let us (<gcc@gcc.gnu.org> and <fortran@gnu.org>) know how
- use of these options affects the performance of your production
- code. We're very interested in code that runs _slower_ when these
- options are _enabled_.
-
-`-fno-peephole'
-`-fno-peephole2'
- Disable any machine-specific peephole optimizations. The
- difference between `-fno-peephole' and `-fno-peephole2' is in how
- they are implemented in the compiler; some targets use one, some
- use the other, a few use both.
-
-`-fbranch-probabilities'
- After running a program compiled with `-fprofile-arcs' (*note
- Options for Debugging Your Program or `gcc': Debugging Options.),
- you can compile it a second time using `-fbranch-probabilities',
- to improve optimizations based on the number of times each branch
- was taken. When the program compiled with `-fprofile-arcs' exits
- it saves arc execution counts to a file called `SOURCENAME.da' for
- each source file The information in this data file is very
- dependent on the structure of the generated code, so you must use
- the same source code and the same optimization options for both
- compilations.
-
- With `-fbranch-probabilities', GCC puts a `REG_EXEC_COUNT' note on
- the first instruction of each basic block, and a `REG_BR_PROB'
- note on each `JUMP_INSN' and `CALL_INSN'. These can be used to
- improve optimization. Currently, they are only used in one place:
- in `reorg.c', instead of guessing which path a branch is mostly to
- take, the `REG_BR_PROB' values are used to exactly determine which
- path is taken more often.
-
-`-fno-guess-branch-probability'
- Do not guess branch probabilities using a randomized model.
-
- Sometimes gcc will opt to use a randomized model to guess branch
- probabilities, when none are available from either profiling
- feedback (`-fprofile-arcs') or `__builtin_expect'. This means that
- different runs of the compiler on the same program may produce
- different object code.
-
- In a hard real-time system, people don't want different runs of the
- compiler to produce code that has different behavior; minimizing
- non-determinism is of paramount import. This switch allows users
- to reduce non-determinism, possibly at the expense of inferior
- optimization.
-
-`-fstrict-aliasing'
- Allows the compiler to assume the strictest aliasing rules
- applicable to the language being compiled. For C (and C++), this
- activates optimizations based on the type of expressions. In
- particular, an object of one type is assumed never to reside at
- the same address as an object of a different type, unless the
- types are almost the same. For example, an `unsigned int' can
- alias an `int', but not a `void*' or a `double'. A character type
- may alias any other type.
-
- Pay special attention to code like this:
- union a_union {
- int i;
- double d;
- };
-
- int f() {
- a_union t;
- t.d = 3.0;
- return t.i;
- }
- The practice of reading from a different union member than the one
- most recently written to (called "type-punning") is common. Even
- with `-fstrict-aliasing', type-punning is allowed, provided the
- memory is accessed through the union type. So, the code above
- will work as expected. However, this code might not:
- int f() {
- a_union t;
- int* ip;
- t.d = 3.0;
- ip = &t.i;
- return *ip;
- }
-
- Every language that wishes to perform language-specific alias
- analysis should define a function that computes, given an `tree'
- node, an alias set for the node. Nodes in different alias sets
- are not allowed to alias. For an example, see the C front-end
- function `c_get_alias_set'.
-
-`-falign-functions'
-`-falign-functions=N'
- Align the start of functions to the next power-of-two greater than
- N, skipping up to N bytes. For instance, `-falign-functions=32'
- aligns functions to the next 32-byte boundary, but
- `-falign-functions=24' would align to the next 32-byte boundary
- only if this can be done by skipping 23 bytes or less.
-
- `-fno-align-functions' and `-falign-functions=1' are equivalent
- and mean that functions will not be aligned.
-
- Some assemblers only support this flag when N is a power of two;
- in that case, it is rounded up.
-
- If N is not specified, use a machine-dependent default.
-
-`-falign-labels'
-`-falign-labels=N'
- Align all branch targets to a power-of-two boundary, skipping up to
- N bytes like `-falign-functions'. This option can easily make
- code slower, because it must insert dummy operations for when the
- branch target is reached in the usual flow of the code.
-
- If `-falign-loops' or `-falign-jumps' are applicable and are
- greater than this value, then their values are used instead.
-
- If N is not specified, use a machine-dependent default which is
- very likely to be `1', meaning no alignment.
-
-`-falign-loops'
-`-falign-loops=N'
- Align loops to a power-of-two boundary, skipping up to N bytes
- like `-falign-functions'. The hope is that the loop will be
- executed many times, which will make up for any execution of the
- dummy operations.
-
- If N is not specified, use a machine-dependent default.
-
-`-falign-jumps'
-`-falign-jumps=N'
- Align branch targets to a power-of-two boundary, for branch targets
- where the targets can only be reached by jumping, skipping up to N
- bytes like `-falign-functions'. In this case, no dummy operations
- need be executed.
-
- If N is not specified, use a machine-dependent default.
-
-`-fssa'
- Perform optimizations in static single assignment form. Each
- function's flow graph is translated into SSA form, optimizations
- are performed, and the flow graph is translated back from SSA
- form. Users should not specify this option, since it is not yet
- ready for production use.
-
-`-fssa-ccp'
- Perform Sparse Conditional Constant Propagation in SSA form.
- Requires `-fssa'. Like `-fssa', this is an experimental feature.
-
-`-fssa-dce'
- Perform aggressive dead-code elimination in SSA form. Requires
- `-fssa'. Like `-fssa', this is an experimental feature.
-
-`-fsingle-precision-constant'
- Treat floating point constant as single precision constant instead
- of implicitly converting it to double precision constant.
-
-`-frename-registers'
- Attempt to avoid false dependencies in scheduled code by making use
- of registers left over after register allocation. This
- optimization will most benefit processors with lots of registers.
- It can, however, make debugging impossible, since variables will
- no longer stay in a "home register".
-
-`-fno-cprop-registers'
- After register allocation and post-register allocation instruction
- splitting, we perform a copy-propagation pass to try to reduce
- scheduling dependencies and occasionally eliminate the copy.
-
-`--param NAME=VALUE'
- In some places, GCC uses various constants to control the amount of
- optimization that is done. For example, GCC will not inline
- functions that contain more that a certain number of instructions.
- You can control some of these constants on the command-line using
- the `--param' option.
-
- In each case, the VALUE is an integer. The allowable choices for
- NAME are given in the following table:
-
- `max-delay-slot-insn-search'
- The maximum number of instructions to consider when looking
- for an instruction to fill a delay slot. If more than this
- arbitrary number of instructions is searched, the time
- savings from filling the delay slot will be minimal so stop
- searching. Increasing values mean more aggressive
- optimization, making the compile time increase with probably
- small improvement in executable run time.
-
- `max-delay-slot-live-search'
- When trying to fill delay slots, the maximum number of
- instructions to consider when searching for a block with
- valid live register information. Increasing this arbitrarily
- chosen value means more aggressive optimization, increasing
- the compile time. This parameter should be removed when the
- delay slot code is rewritten to maintain the control-flow
- graph.
-
- `max-gcse-memory'
- The approximate maximum amount of memory that will be
- allocated in order to perform the global common subexpression
- elimination optimization. If more memory than specified is
- required, the optimization will not be done.
-
- `max-gcse-passes'
- The maximum number of passes of GCSE to run.
-
- `max-pending-list-length'
- The maximum number of pending dependencies scheduling will
- allow before flushing the current state and starting over.
- Large functions with few branches or calls can create
- excessively large lists which needlessly consume memory and
- resources.
-
- `max-inline-insns'
- If an function contains more than this many instructions, it
- will not be inlined. This option is precisely equivalent to
- `-finline-limit'.
+File: gcc.info, Node: Index, Prev: Option Index, Up: Top
+
+Index
+*****
+
+\0\b[index\0\b]
+* Menu:
+
+* ! in constraint: Multi-Alternative. (line 33)
+* # in constraint: Modifiers. (line 51)
+* #pragma: Pragmas. (line 6)
+* #pragma implementation: C++ Interface. (line 52)
+* #pragma implementation, implied: C++ Interface. (line 59)
+* #pragma interface: C++ Interface. (line 33)
+* #pragma, reason for not using: Function Attributes. (line 462)
+* $: Dollar Signs. (line 6)
+* % in constraint: Modifiers. (line 45)
+* %include: Spec Files. (line 27)
+* %include_noerr: Spec Files. (line 31)
+* %rename: Spec Files. (line 35)
+* & in constraint: Modifiers. (line 25)
+* ': Incompatibilities. (line 141)
+* * in constraint: Modifiers. (line 56)
+* + in constraint: Modifiers. (line 12)
+* -lgcc, use with -nodefaultlibs: Link Options. (line 81)
+* -lgcc, use with -nostdlib: Link Options. (line 81)
+* -nodefaultlibs and unresolved references: Link Options. (line 81)
+* -nostdlib and unresolved references: Link Options. (line 81)
+* .sdata/.sdata2 references (PowerPC): RS/6000 and PowerPC Options.
+ (line 458)
+* //: C++ Comments. (line 6)
+* 0 in constraint: Simple Constraints. (line 115)
+* < in constraint: Simple Constraints. (line 46)
+* <?: Min and Max. (line 10)
+* = in constraint: Modifiers. (line 8)
+* > in constraint: Simple Constraints. (line 50)
+* >?: Min and Max. (line 14)
+* ? in constraint: Multi-Alternative. (line 27)
+* ?: extensions <1>: Conditionals. (line 6)
+* ?: extensions: Lvalues. (line 6)
+* ?: side effect: Conditionals. (line 20)
+* \a: C Dialect Options. (line 219)
+* \x: C Dialect Options. (line 219)
+* _ in variables in macros: Typeof. (line 42)
+* __builtin_apply: Constructing Calls. (line 26)
+* __builtin_apply_args: Constructing Calls. (line 15)
+* __builtin_choose_expr: Other Builtins. (line 106)
+* __builtin_constant_p: Other Builtins. (line 144)
+* __builtin_expect: Other Builtins. (line 190)
+* __builtin_frame_address: Return Address. (line 31)
+* __builtin_isgreater: Other Builtins. (line 6)
+* __builtin_isgreaterequal: Other Builtins. (line 6)
+* __builtin_isless: Other Builtins. (line 6)
+* __builtin_islessequal: Other Builtins. (line 6)
+* __builtin_islessgreater: Other Builtins. (line 6)
+* __builtin_isunordered: Other Builtins. (line 6)
+* __builtin_prefetch: Other Builtins. (line 215)
+* __builtin_return: Constructing Calls. (line 43)
+* __builtin_return_address: Return Address. (line 11)
+* __builtin_types_compatible_p: Other Builtins. (line 61)
+* __complex__ keyword: Complex. (line 6)
+* __extension__: Alternate Keywords. (line 33)
+* __func__ identifier: Function Names. (line 6)
+* __FUNCTION__ identifier: Function Names. (line 6)
+* __imag__ keyword: Complex. (line 27)
+* __PRETTY_FUNCTION__ identifier: Function Names. (line 6)
+* __real__ keyword: Complex. (line 27)
+* __STDC_HOSTED__: Standards. (line 6)
+* _Complex keyword: Complex. (line 6)
+* _Exit: Other Builtins. (line 6)
+* _exit: Other Builtins. (line 6)
+* ABI: Compatibility. (line 6)
+* abort: Other Builtins. (line 6)
+* abs: Other Builtins. (line 6)
+* accessing volatiles: Volatiles. (line 6)
+* Ada: G++ and GCC. (line 6)
+* address constraints: Simple Constraints. (line 142)
+* address of a label: Labels as Values. (line 6)
+* address_operand: Simple Constraints. (line 146)
+* alias attribute: Function Attributes. (line 281)
+* aliasing of parameters: Code Gen Options. (line 315)
+* aligned attribute <1>: Type Attributes. (line 30)
+* aligned attribute: Variable Attributes. (line 25)
+* alignment: Alignment. (line 6)
+* Alliant: Interoperation. (line 217)
+* alloca: Other Builtins. (line 6)
+* alloca vs variable-length arrays: Variable Length. (line 27)
+* alternate keywords: Alternate Keywords. (line 6)
+* always_inline function attribute: Function Attributes. (line 70)
+* AMD x86-64 Options: i386 and x86-64 Options.
+ (line 6)
+* AMD1: Standards. (line 6)
+* AMD29K options: AMD29K Options. (line 6)
+* ANSI C: Standards. (line 6)
+* ANSI C standard: Standards. (line 6)
+* ANSI C89: Standards. (line 6)
+* ANSI support: C Dialect Options. (line 9)
+* ANSI X3.159-1989: Standards. (line 6)
+* apostrophes: Incompatibilities. (line 141)
+* application binary interface: Compatibility. (line 6)
+* ARC Options: ARC Options. (line 6)
+* arguments in frame (88k): M88K Options. (line 58)
+* ARM [Annotated C++ Reference Manual]: Backwards Compatibility.
+ (line 6)
+* ARM options: ARM Options. (line 6)
+* arrays of length zero: Zero Length. (line 6)
+* arrays of variable length: Variable Length. (line 6)
+* arrays, non-lvalue: Subscripting. (line 6)
+* asm constraints: Constraints. (line 6)
+* asm expressions: Extended Asm. (line 6)
+* assembler instructions: Extended Asm. (line 6)
+* assembler names for identifiers: Asm Labels. (line 6)
+* assembler syntax, 88k: M88K Options. (line 103)
+* assembly code, invalid: Bug Criteria. (line 12)
+* attribute of types: Type Attributes. (line 6)
+* attribute of variables: Variable Attributes. (line 6)
+* attribute syntax: Attribute Syntax. (line 6)
+* autoincrement/decrement addressing: Simple Constraints. (line 28)
+* automatic inline for C++ member fns: Inline. (line 46)
+* AVR Options: AVR Options. (line 6)
+* backtrace for bug reports: Bug Reporting. (line 158)
+* Backwards Compatibility: Backwards Compatibility.
+ (line 6)
+* bcmp: Other Builtins. (line 6)
+* binary compatibility: Compatibility. (line 6)
+* bit shift overflow (88k): M88K Options. (line 169)
+* bound pointer to member function: Bound member functions.
+ (line 6)
+* bug criteria: Bug Criteria. (line 6)
+* bug report mailing lists: Bug Lists. (line 6)
+* bugs: Bugs. (line 6)
+* bugs, known: Trouble. (line 6)
+* built-in functions <1>: Other Builtins. (line 6)
+* built-in functions: C Dialect Options. (line 122)
+* byte writes (29k): AMD29K Options. (line 17)
+* bzero: Other Builtins. (line 6)
+* C compilation options: Invoking GCC. (line 17)
+* C intermediate output, nonexistent: G++ and GCC. (line 42)
+* C language extensions: C Extensions. (line 6)
+* C language, traditional: C Dialect Options. (line 186)
+* C standard: Standards. (line 6)
+* C standards: Standards. (line 6)
+* c++: Invoking G++. (line 12)
+* C++: G++ and GCC. (line 17)
+* C++ comments: C++ Comments. (line 6)
+* C++ compilation options: Invoking GCC. (line 23)
+* C++ interface and implementation headers: C++ Interface. (line 6)
+* C++ language extensions: C++ Extensions. (line 6)
+* C++ member fns, automatically inline: Inline. (line 46)
+* C++ misunderstandings: C++ Misunderstandings.
+ (line 6)
+* C++ options, command line: C++ Dialect Options. (line 6)
+* C++ pragmas, effect on inlining: C++ Interface. (line 82)
+* C++ source file suffixes: Invoking G++. (line 6)
+* C++ static data, declaring and defining: Static Definitions.
+ (line 6)
+* C89: Standards. (line 6)
+* C90: Standards. (line 6)
+* C94: Standards. (line 6)
+* C95: Standards. (line 6)
+* C99: Standards. (line 6)
+* C9X: Standards. (line 6)
+* C_INCLUDE_PATH: Environment Variables.
+ (line 124)
+* calling functions through the function vector on the H8/300 processors: Function Attributes.
+ (line 356)
+* case labels in initializers: Designated Inits. (line 6)
+* case ranges: Case Ranges. (line 6)
+* case sensitivity and VMS: VMS Misc. (line 27)
+* cast to a union: Cast to Union. (line 6)
+* casts as lvalues: Lvalues. (line 6)
+* cimag: Other Builtins. (line 6)
+* cimagf: Other Builtins. (line 6)
+* cimagl: Other Builtins. (line 6)
+* code generation conventions: Code Gen Options. (line 6)
+* code, mixed with declarations: Mixed Declarations. (line 6)
+* command options: Invoking GCC. (line 6)
+* comments, C++ style: C++ Comments. (line 6)
+* comparison of signed and unsigned values, warning: Warning Options.
+ (line 634)
+* compiler bugs, reporting: Bug Reporting. (line 6)
+* compiler compared to C++ preprocessor: G++ and GCC. (line 42)
+* compiler options, C++: C++ Dialect Options. (line 6)
+* compiler options, Objective-C: Objective-C Dialect Options.
+ (line 6)
+* compiler version, specifying: Target Options. (line 6)
+* COMPILER_PATH: Environment Variables.
+ (line 85)
+* complex conjugation: Complex. (line 34)
+* complex numbers: Complex. (line 6)
+* compound expressions as lvalues: Lvalues. (line 6)
+* compound literals: Compound Literals. (line 6)
+* computed gotos: Labels as Values. (line 6)
+* conditional expressions as lvalues: Lvalues. (line 6)
+* conditional expressions, extensions: Conditionals. (line 6)
+* conflicting types: Disappointments. (line 21)
+* conj: Other Builtins. (line 6)
+* conjf: Other Builtins. (line 6)
+* conjl: Other Builtins. (line 6)
+* const applied to function: Function Attributes. (line 6)
+* const function attribute: Function Attributes. (line 95)
+* constants in constraints: Simple Constraints. (line 58)
+* constraint modifier characters: Modifiers. (line 6)
+* constraint, matching: Simple Constraints. (line 127)
+* constraints, asm: Constraints. (line 6)
+* constraints, machine specific: Machine Constraints. (line 6)
+* constructing calls: Constructing Calls. (line 6)
+* constructor expressions: Compound Literals. (line 6)
+* constructor function attribute: Function Attributes. (line 226)
+* contributors: Contributors. (line 6)
+* Convex options: Convex Options. (line 6)
+* core dump: Bug Criteria. (line 9)
+* cos: Other Builtins. (line 6)
+* cosf: Other Builtins. (line 6)
+* cosl: Other Builtins. (line 6)
+* CPATH: Environment Variables.
+ (line 123)
+* CPLUS_INCLUDE_PATH: Environment Variables.
+ (line 125)
+* creal: Other Builtins. (line 6)
+* crealf: Other Builtins. (line 6)
+* creall: Other Builtins. (line 6)
+* CRIS Options: CRIS Options. (line 6)
+* cross compiling: Target Options. (line 6)
+* D30V Options: D30V Options. (line 6)
+* DBX: Interoperation. (line 28)
+* deallocating variable length arrays: Variable Length. (line 23)
+* debug_rtx: Bug Reporting. (line 176)
+* debugging information options: Debugging Options. (line 6)
+* debugging, 88k OCS: M88K Options. (line 34)
+* declaration scope: Incompatibilities. (line 97)
+* declarations inside expressions: Statement Exprs. (line 6)
+* declarations, mixed with code: Mixed Declarations. (line 6)
+* declaring attributes of functions: Function Attributes. (line 6)
+* declaring static data in C++: Static Definitions. (line 6)
+* defining static data in C++: Static Definitions. (line 6)
+* dependencies for make as output: Environment Variables.
+ (line 145)
+* dependencies, make: Preprocessor Options.
+ (line 123)
+* DEPENDENCIES_OUTPUT: Environment Variables.
+ (line 144)
+* deprecated attribute.: Function Attributes. (line 248)
+* designated initializers: Designated Inits. (line 6)
+* designator lists: Designated Inits. (line 94)
+* designators: Designated Inits. (line 61)
+* destructor function attribute: Function Attributes. (line 226)
+* diagnostic messages: Language Independent Options.
+ (line 6)
+* dialect options: C Dialect Options. (line 6)
+* digits in constraint: Simple Constraints. (line 115)
+* directory options: Directory Options. (line 6)
+* divide instruction, 88k: M88K Options. (line 141)
+* dollar signs in identifier names: Dollar Signs. (line 6)
+* double-word arithmetic: Long Long. (line 6)
+* downward funargs: Nested Functions. (line 6)
+* DW bit (29k): AMD29K Options. (line 9)
+* E in constraint: Simple Constraints. (line 77)
+* earlyclobber operand: Modifiers. (line 25)
+* eight bit data on the H8/300 and H8/300H: Function Attributes.
+ (line 408)
+* environment variables: Environment Variables.
+ (line 6)
+* error messages: Warnings and Errors. (line 6)
+* escape sequences, traditional: C Dialect Options. (line 219)
+* escaped newlines: Escaped Newlines. (line 6)
+* exclamation point: Multi-Alternative. (line 33)
+* exit: Other Builtins. (line 6)
+* exit status and VMS: VMS Misc. (line 6)
+* explicit register variables: Explicit Reg Vars. (line 6)
+* expressions containing statements: Statement Exprs. (line 6)
+* expressions, compound, as lvalues: Lvalues. (line 6)
+* expressions, conditional, as lvalues: Lvalues. (line 6)
+* expressions, constructor: Compound Literals. (line 6)
+* extended asm: Extended Asm. (line 6)
+* extensible constraints: Simple Constraints. (line 151)
+* extensions, ?: <1>: Conditionals. (line 6)
+* extensions, ?:: Lvalues. (line 6)
+* extensions, C language: C Extensions. (line 6)
+* extensions, C++ language: C++ Extensions. (line 6)
+* external declaration scope: Incompatibilities. (line 97)
+* F in constraint: Simple Constraints. (line 82)
+* fabs: Other Builtins. (line 6)
+* fabsf: Other Builtins. (line 6)
+* fabsl: Other Builtins. (line 6)
+* fatal signal: Bug Criteria. (line 9)
+* FDL, GNU Free Documentation License: GNU Free Documentation License.
+ (line 6)
+* ffs: Other Builtins. (line 6)
+* file name suffix: Overall Options. (line 12)
+* file names: Link Options. (line 10)
+* flexible array members: Zero Length. (line 6)
+* float as function value type: Incompatibilities. (line 167)
+* floating point precision <1>: Disappointments. (line 70)
+* floating point precision: Optimize Options. (line 68)
+* format function attribute: Function Attributes. (line 123)
+* format_arg function attribute: Function Attributes. (line 168)
+* Fortran: G++ and GCC. (line 6)
+* forwarding calls: Constructing Calls. (line 6)
+* fprintf: Other Builtins. (line 6)
+* fprintf_unlocked: Other Builtins. (line 6)
+* fputs: Other Builtins. (line 6)
+* fputs_unlocked: Other Builtins. (line 6)
+* freestanding environment: Standards. (line 6)
+* freestanding implementation: Standards. (line 6)
+* fscanf, and constant strings: Incompatibilities. (line 19)
+* function addressability on the M32R/D: Function Attributes. (line 438)
+* function attributes: Function Attributes. (line 6)
+* function pointers, arithmetic: Pointer Arith. (line 6)
+* function prototype declarations: Function Prototypes. (line 6)
+* function without a prologue/epilogue code: Function Attributes.
+ (line 432)
+* function, size of pointer to: Pointer Arith. (line 6)
+* functions called via pointer on the RS/6000 and PowerPC: Function Attributes.
+ (line 317)
+* functions in arbitrary sections: Function Attributes. (line 6)
+* functions that are passed arguments in registers on the 386: Function Attributes.
+ (line 6)
+* functions that behave like malloc: Function Attributes. (line 6)
+* functions that do not pop the argument stack on the 386: Function Attributes.
+ (line 6)
+* functions that do pop the argument stack on the 386: Function Attributes.
+ (line 308)
+* functions that have no side effects: Function Attributes. (line 6)
+* functions that never return: Function Attributes. (line 6)
+* functions that pop the argument stack on the 386: Function Attributes.
+ (line 6)
+* functions which are exported from a dll on PowerPC Windows NT: Function Attributes.
+ (line 340)
+* functions which are imported from a dll on PowerPC Windows NT: Function Attributes.
+ (line 333)
+* functions which specify exception handling on PowerPC Windows NT: Function Attributes.
+ (line 346)
+* functions with printf, scanf, strftime or strfmon style arguments: Function Attributes.
+ (line 6)
+* g in constraint: Simple Constraints. (line 108)
+* G in constraint: Simple Constraints. (line 86)
+* g++: Invoking G++. (line 12)
+* G++: G++ and GCC. (line 17)
+* GCC: G++ and GCC. (line 12)
+* GCC command options: Invoking GCC. (line 6)
+* gcc-bugs@gcc.gnu.org or bug-gcc@gnu.org: Bug Lists. (line 6)
+* GCC_EXEC_PREFIX: Environment Variables.
+ (line 52)
+* gccbug script: gccbug. (line 6)
+* generalized lvalues: Lvalues. (line 6)
+* global offset table: Code Gen Options. (line 172)
+* global register after longjmp: Global Reg Vars. (line 66)
+* global register variables: Global Reg Vars. (line 6)
+* GLOBALDEF: Global Declarations. (line 6)
+* GLOBALREF: Global Declarations. (line 6)
+* GLOBALVALUEDEF: Global Declarations. (line 6)
+* GLOBALVALUEREF: Global Declarations. (line 6)
+* GNAT: G++ and GCC. (line 22)
+* goto with computed label: Labels as Values. (line 6)
+* gp-relative references (MIPS): MIPS Options. (line 253)
+* gprof: Debugging Options. (line 124)
+* grouping options: Invoking GCC. (line 26)
+* H in constraint: Simple Constraints. (line 86)
+* hardware models and configurations, specifying: Submodel Options.
+ (line 6)
+* header files and VMS: Include Files and VMS.
+ (line 6)
+* hex floats: Hex Floats. (line 6)
+* hosted environment <1>: C Dialect Options. (line 157)
+* hosted environment: Standards. (line 6)
+* hosted implementation: Standards. (line 6)
+* HPPA Options: HPPA Options. (line 6)
+* I in constraint: Simple Constraints. (line 69)
+* i in constraint: Simple Constraints. (line 58)
+* i386 Options: i386 and x86-64 Options.
+ (line 6)
+* IA-64 Options: IA-64 Options. (line 6)
+* IBM RS/6000 and PowerPC Options: RS/6000 and PowerPC Options.
+ (line 6)
+* IBM RT options: RT Options. (line 6)
+* IBM RT PC: Interoperation. (line 221)
+* identifier names, dollar signs in: Dollar Signs. (line 6)
+* identifiers, names in assembler code: Asm Labels. (line 6)
+* identifying source, compiler (88k): M88K Options. (line 23)
+* imaxabs: Other Builtins. (line 6)
+* implementation-defined behavior, C language: C Implementation.
+ (line 6)
+* implied #pragma implementation: C++ Interface. (line 59)
+* include files and VMS: Include Files and VMS.
+ (line 6)
+* incompatibilities of GCC: Incompatibilities. (line 6)
+* increment operators: Bug Criteria. (line 17)
+* index: Other Builtins. (line 6)
+* indirect calls on ARM: Function Attributes. (line 323)
+* init_priority attribute: C++ Attributes. (line 9)
+* initializations in expressions: Compound Literals. (line 6)
+* initializers with labeled elements: Designated Inits. (line 6)
+* initializers, non-constant: Initializers. (line 6)
+* inline automatic for C++ member fns: Inline. (line 46)
+* inline functions: Inline. (line 6)
+* inline functions, omission of: Inline. (line 51)
+* inlining and C++ pragmas: C++ Interface. (line 82)
+* installation trouble: Trouble. (line 6)
+* integrating function code: Inline. (line 6)
+* Intel 386 Options: i386 and x86-64 Options.
+ (line 6)
+* interface and implementation headers, C++: C++ Interface. (line 6)
+* intermediate C version, nonexistent: G++ and GCC. (line 42)
+* interrupt handler functions: Function Attributes. (line 367)
+* interrupt handler functions on the H8/300 and SH processors: Function Attributes.
+ (line 387)
+* introduction: Top. (line 6)
+* invalid assembly code: Bug Criteria. (line 12)
+* invalid input: Bug Criteria. (line 47)
+* invoking g++: Invoking G++. (line 20)
+* ISO 9899: Standards. (line 6)
+* ISO C: Standards. (line 6)
+* ISO C standard: Standards. (line 6)
+* ISO C89: Standards. (line 6)
+* ISO C90: Standards. (line 6)
+* ISO C94: Standards. (line 6)
+* ISO C95: Standards. (line 6)
+* ISO C99: Standards. (line 6)
+* ISO C9X: Standards. (line 6)
+* ISO support: C Dialect Options. (line 9)
+* ISO/IEC 9899: Standards. (line 6)
+* Java: G++ and GCC. (line 6)
+* java_interface attribute: C++ Attributes. (line 29)
+* kernel and user registers (29k): AMD29K Options. (line 48)
+* keywords, alternate: Alternate Keywords. (line 6)
+* known causes of trouble: Trouble. (line 6)
+* labeled elements in initializers: Designated Inits. (line 6)
+* labels as values: Labels as Values. (line 6)
+* labs: Other Builtins. (line 6)
+* LANG: Environment Variables.
+ (line 21)
+* language dialect options: C Dialect Options. (line 6)
+* large bit shifts (88k): M88K Options. (line 169)
+* LC_ALL: Environment Variables.
+ (line 21)
+* LC_CTYPE: Environment Variables.
+ (line 21)
+* LC_MESSAGES: Environment Variables.
+ (line 21)
+* length-zero arrays: Zero Length. (line 6)
+* Libraries: Link Options. (line 24)
+* LIBRARY_PATH: Environment Variables.
+ (line 91)
+* link options: Link Options. (line 6)
+* LL integer suffix: Long Long. (line 6)
+* llabs: Other Builtins. (line 6)
+* load address instruction: Simple Constraints. (line 142)
+* local labels: Local Labels. (line 6)
+* local variables in macros: Typeof. (line 42)
+* local variables, specifying registers: Local Reg Vars. (line 6)
+* locale: Environment Variables.
+ (line 21)
+* locale definition: Environment Variables.
+ (line 100)
+* long long data types: Long Long. (line 6)
+* longjmp: Global Reg Vars. (line 66)
+* longjmp and automatic variables: C Dialect Options. (line 215)
+* longjmp incompatibilities: Incompatibilities. (line 47)
+* longjmp warnings: Warning Options. (line 371)
+* lvalues, generalized: Lvalues. (line 6)
+* m in constraint: Simple Constraints. (line 17)
+* M32R/D options: M32R/D Options. (line 6)
+* M680x0 options: M680x0 Options. (line 6)
+* M68hc1x options: M68hc1x Options. (line 6)
+* M88k options: M88K Options. (line 6)
+* machine dependent options: Submodel Options. (line 6)
+* machine specific constraints: Machine Constraints. (line 6)
+* macro with variable arguments: Variadic Macros. (line 6)
+* macros containing asm: Extended Asm. (line 195)
+* macros, inline alternative: Inline. (line 6)
+* macros, local labels: Local Labels. (line 6)
+* macros, local variables in: Typeof. (line 42)
+* macros, statements in expressions: Statement Exprs. (line 6)
+* macros, types of arguments: Typeof. (line 6)
+* main and the exit status: VMS Misc. (line 6)
+* make: Preprocessor Options.
+ (line 123)
+* malloc attribute: Function Attributes. (line 275)
+* matching constraint: Simple Constraints. (line 127)
+* maximum operator: Min and Max. (line 14)
+* MCore options: MCore Options. (line 6)
+* member fns, automatically inline: Inline. (line 46)
+* memcmp: Other Builtins. (line 6)
+* memcpy: Other Builtins. (line 6)
+* memory model (29k): AMD29K Options. (line 25)
+* memory references in constraints: Simple Constraints. (line 17)
+* memset: Other Builtins. (line 6)
+* message formatting: Language Independent Options.
+ (line 6)
+* messages, warning: Warning Options. (line 6)
+* messages, warning and error: Warnings and Errors. (line 6)
+* middle-operands, omitted: Conditionals. (line 6)
+* minimum operator: Min and Max. (line 10)
+* MIPS options: MIPS Options. (line 6)
+* misunderstandings in C++: C++ Misunderstandings.
+ (line 6)
+* mixed declarations and code: Mixed Declarations. (line 6)
+* mktemp, and constant strings: Incompatibilities. (line 15)
+* MMIX Options: MMIX Options. (line 6)
+* MN10200 options: MN10200 Options. (line 6)
+* MN10300 options: MN10300 Options. (line 6)
+* mode attribute: Variable Attributes. (line 78)
+* modifiers in constraints: Modifiers. (line 6)
+* multi-line string literals: Multi-line Strings. (line 6)
+* multiple alternative constraints: Multi-Alternative. (line 6)
+* multiprecision arithmetic: Long Long. (line 6)
+* n in constraint: Simple Constraints. (line 63)
+* name augmentation: VMS Misc. (line 27)
+* names used in assembler code: Asm Labels. (line 6)
+* naming convention, implementation headers: C++ Interface. (line 59)
+* nested functions: Nested Functions. (line 6)
+* newlines (escaped): Escaped Newlines. (line 6)
+* no_instrument_function function attribute: Function Attributes.
+ (line 204)
+* nocommon attribute: Variable Attributes. (line 89)
+* noinline function attribute: Function Attributes. (line 66)
+* non-constant initializers: Initializers. (line 6)
+* non-static inline function: Inline. (line 63)
+* noreturn function attribute: Function Attributes. (line 30)
+* NS32K options: NS32K Options. (line 6)
+* o in constraint: Simple Constraints. (line 21)
+* OBJC_INCLUDE_PATH: Environment Variables.
+ (line 126)
+* Objective-C: G++ and GCC. (line 6)
+* Objective-C options, command line: Objective-C Dialect Options.
+ (line 6)
+* OCS (88k): M88K Options. (line 34)
+* offsettable address: Simple Constraints. (line 21)
+* old-style function definitions: Function Prototypes. (line 6)
+* omitted middle-operands: Conditionals. (line 6)
+* open coding: Inline. (line 6)
+* operand constraints, asm: Constraints. (line 6)
+* optimize options: Optimize Options. (line 6)
+* options to control diagnostics formatting: Language Independent Options.
+ (line 6)
+* options to control warnings: Warning Options. (line 6)
+* options, C++: C++ Dialect Options. (line 6)
+* options, code generation: Code Gen Options. (line 6)
+* options, debugging: Debugging Options. (line 6)
+* options, dialect: C Dialect Options. (line 6)
+* options, directory search: Directory Options. (line 6)
+* options, GCC command: Invoking GCC. (line 6)
+* options, grouping: Invoking GCC. (line 26)
+* options, linking: Link Options. (line 6)
+* options, Objective-C: Objective-C Dialect Options.
+ (line 6)
+* options, optimization: Optimize Options. (line 6)
+* options, order: Invoking GCC. (line 30)
+* options, preprocessor: Preprocessor Options.
+ (line 6)
+* order of evaluation, side effects: Non-bugs. (line 175)
+* order of options: Invoking GCC. (line 30)
+* other register constraints: Simple Constraints. (line 151)
+* output file option: Overall Options. (line 145)
+* overloaded virtual fn, warning: C++ Dialect Options. (line 344)
+* p in constraint: Simple Constraints. (line 142)
+* packed attribute: Variable Attributes. (line 98)
+* parameter forward declaration: Variable Length. (line 60)
+* parameters, aliased: Code Gen Options. (line 315)
+* PDP-11 Options: PDP-11 Options. (line 6)
+* PIC: Code Gen Options. (line 172)
+* pmf: Bound member functions.
+ (line 6)
+* pointer arguments: Function Attributes. (line 103)
+* pointer to member function: Bound member functions.
+ (line 6)
+* portions of temporary objects, pointers to: Temporaries. (line 6)
+* pragma, extern_prefix: Tru64 Pragmas. (line 10)
+* pragma, long_calls: ARM Pragmas. (line 11)
+* pragma, long_calls_off: ARM Pragmas. (line 17)
+* pragma, mark: Darwin Pragmas. (line 11)
+* pragma, no_long_calls: ARM Pragmas. (line 14)
+* pragma, options align: Darwin Pragmas. (line 14)
+* pragma, reason for not using: Function Attributes. (line 462)
+* pragma, redefine_extname: Solaris Pragmas. (line 10)
+* pragma, segment: Darwin Pragmas. (line 21)
+* pragma, unused: Darwin Pragmas. (line 24)
+* pragmas: Pragmas. (line 6)
+* pragmas in C++, effect on inlining: C++ Interface. (line 82)
+* pragmas, interface and implementation: C++ Interface. (line 16)
+* pragmas, warning of unknown: Warning Options. (line 390)
+* preprocessing numbers: Incompatibilities. (line 200)
+* preprocessing tokens: Incompatibilities. (line 200)
+* preprocessor options: Preprocessor Options.
+ (line 6)
+* printf: Other Builtins. (line 6)
+* printf_unlocked: Other Builtins. (line 6)
+* processor selection (29k): AMD29K Options. (line 42)
+* prof: Debugging Options. (line 118)
+* promotion of formal parameters: Function Prototypes. (line 6)
+* pure function attribute: Function Attributes. (line 75)
+* push address instruction: Simple Constraints. (line 142)
+* qsort, and global register variables: Global Reg Vars. (line 42)
+* question mark: Multi-Alternative. (line 27)
+* r in constraint: Simple Constraints. (line 54)
+* r0-relative references (88k): M88K Options. (line 68)
+* ranges in case statements: Case Ranges. (line 6)
+* read-only strings: Incompatibilities. (line 11)
+* register positions in frame (88k): M88K Options. (line 43)
+* register variable after longjmp: Global Reg Vars. (line 66)
+* registers: Extended Asm. (line 6)
+* registers for local variables: Local Reg Vars. (line 6)
+* registers in constraints: Simple Constraints. (line 54)
+* registers, global allocation: Explicit Reg Vars. (line 6)
+* registers, global variables in: Global Reg Vars. (line 6)
+* reordering, warning <1>: Warning Options. (line 386)
+* reordering, warning: C++ Dialect Options. (line 272)
+* reporting bugs: Bugs. (line 6)
+* rest argument (in macro): Variadic Macros. (line 6)
+* restricted pointers: Restricted Pointers. (line 6)
+* restricted references: Restricted Pointers. (line 6)
+* restricted this pointer: Restricted Pointers. (line 6)
+* return value of main: VMS Misc. (line 6)
+* rindex: Other Builtins. (line 6)
+* RS/6000 and PowerPC Options: RS/6000 and PowerPC Options.
+ (line 6)
+* RT options: RT Options. (line 6)
+* RT PC: Interoperation. (line 221)
+* RTTI: Vague Linkage. (line 43)
+* run-time options: Code Gen Options. (line 6)
+* s in constraint: Simple Constraints. (line 90)
+* S/390 and zSeries Options: S/390 and zSeries Options.
+ (line 6)
+* scanf, and constant strings: Incompatibilities. (line 19)
+* scope of a variable length array: Variable Length. (line 23)
+* scope of declaration: Disappointments. (line 21)
+* scope of external declarations: Incompatibilities. (line 97)
+* search path: Directory Options. (line 6)
+* section function attribute: Function Attributes. (line 209)
+* section variable attribute: Variable Attributes. (line 113)
+* sequential consistency on 88k: M88K Options. (line 78)
+* setjmp: Global Reg Vars. (line 66)
+* setjmp incompatibilities: Incompatibilities. (line 47)
+* shared strings: Incompatibilities. (line 11)
+* shared variable attribute: Variable Attributes. (line 158)
+* shared VMS run time system: VMS Misc. (line 16)
+* side effect in ?:: Conditionals. (line 20)
+* side effects, macro argument: Statement Exprs. (line 35)
+* side effects, order of evaluation: Non-bugs. (line 175)
+* signal handler functions on the AVR processors: Function Attributes.
+ (line 425)
+* signed and unsigned values, comparison warning: Warning Options.
+ (line 634)
+* simple constraints: Simple Constraints. (line 6)
+* sin: Other Builtins. (line 6)
+* sinf: Other Builtins. (line 6)
+* sinl: Other Builtins. (line 6)
+* sizeof: Typeof. (line 6)
+* smaller data references: M32R/D Options. (line 54)
+* smaller data references (88k): M88K Options. (line 68)
+* smaller data references (MIPS): MIPS Options. (line 253)
+* smaller data references (PowerPC): RS/6000 and PowerPC Options.
+ (line 458)
+* SPARC options: SPARC Options. (line 6)
+* Spec Files: Spec Files. (line 6)
+* specified registers: Explicit Reg Vars. (line 6)
+* specifying compiler version and target machine: Target Options.
+ (line 6)
+* specifying hardware config: Submodel Options. (line 6)
+* specifying machine version: Target Options. (line 6)
+* specifying registers for local variables: Local Reg Vars. (line 6)
+* sqrt: Other Builtins. (line 6)
+* sqrtf: Other Builtins. (line 6)
+* sqrtl: Other Builtins. (line 6)
+* sscanf, and constant strings: Incompatibilities. (line 19)
+* stack checks (29k): AMD29K Options. (line 62)
+* statements inside expressions: Statement Exprs. (line 6)
+* static data in C++, declaring and defining: Static Definitions.
+ (line 6)
+* stdarg.h and RT PC: RT Options. (line 25)
+* storem bug (29k): AMD29K Options. (line 67)
+* strcat: Other Builtins. (line 6)
+* strchr: Other Builtins. (line 6)
+* strcmp: Other Builtins. (line 6)
+* strcpy: Other Builtins. (line 6)
+* strcspn: Other Builtins. (line 6)
+* string constants: Incompatibilities. (line 11)
+* strlen: Other Builtins. (line 6)
+* strncat: Other Builtins. (line 6)
+* strncmp: Other Builtins. (line 6)
+* strncpy: Other Builtins. (line 6)
+* strpbrk: Other Builtins. (line 6)
+* strrchr: Other Builtins. (line 6)
+* strspn: Other Builtins. (line 6)
+* strstr: Other Builtins. (line 6)
+* struct: Unnamed Fields. (line 6)
+* structure passing (88k): M88K Options. (line 175)
+* structures: Incompatibilities. (line 172)
+* structures, constructor expression: Compound Literals. (line 6)
+* submodel options: Submodel Options. (line 6)
+* subscripting: Subscripting. (line 6)
+* subscripting and function values: Subscripting. (line 6)
+* suffixes for C++ source: Invoking G++. (line 6)
+* SUNPRO_DEPENDENCIES: Environment Variables.
+ (line 160)
+* suppressing warnings: Warning Options. (line 6)
+* surprises in C++: C++ Misunderstandings.
+ (line 6)
+* SVr4: M88K Options. (line 103)
+* syntax checking: Warning Options. (line 21)
+* synthesized methods, warning: C++ Dialect Options. (line 374)
+* system headers, warnings from: Warning Options. (line 416)
+* target machine, specifying: Target Options. (line 6)
+* target options: Target Options. (line 6)
+* TC1: Standards. (line 6)
+* TC2: Standards. (line 6)
+* Technical Corrigenda: Standards. (line 6)
+* Technical Corrigendum 1: Standards. (line 6)
+* Technical Corrigendum 2: Standards. (line 6)
+* template instantiation: Template Instantiation.
+ (line 6)
+* temporaries, lifetime of: Temporaries. (line 6)
+* thunks: Nested Functions. (line 6)
+* tiny data section on the H8/300H: Function Attributes. (line 418)
+* TMPDIR: Environment Variables.
+ (line 45)
+* TMS320C3x/C4x Options: TMS320C3x/C4x Options.
+ (line 6)
+* traditional C language: C Dialect Options. (line 186)
+* type alignment: Alignment. (line 6)
+* type attributes: Type Attributes. (line 6)
+* type_info: Vague Linkage. (line 43)
+* typedef names as function parameters: Incompatibilities. (line 119)
+* typeof: Typeof. (line 6)
+* ULL integer suffix: Long Long. (line 6)
+* Ultrix calling convention: Interoperation. (line 226)
+* undefined behavior: Bug Criteria. (line 17)
+* undefined function value: Bug Criteria. (line 17)
+* underscores in variables in macros: Typeof. (line 42)
+* underscores, avoiding (88k): M88K Options. (line 28)
+* union: Unnamed Fields. (line 6)
+* union, casting to a: Cast to Union. (line 6)
+* unions: Incompatibilities. (line 172)
+* unknown pragmas, warning: Warning Options. (line 390)
+* unresolved references and -nodefaultlibs: Link Options. (line 81)
+* unresolved references and -nostdlib: Link Options. (line 81)
+* unused attribute.: Function Attributes. (line 236)
+* used attribute.: Function Attributes. (line 242)
+* V in constraint: Simple Constraints. (line 41)
+* V850 Options: V850 Options. (line 6)
+* vague linkage: Vague Linkage. (line 6)
+* value after longjmp: Global Reg Vars. (line 66)
+* varargs.h and RT PC: RT Options. (line 25)
+* variable addressability on the M32R/D: Variable Attributes. (line 241)
+* variable alignment: Alignment. (line 6)
+* variable attributes: Variable Attributes. (line 6)
+* variable number of arguments: Variadic Macros. (line 6)
+* variable-length array scope: Variable Length. (line 23)
+* variable-length arrays: Variable Length. (line 6)
+* variables in specified registers: Explicit Reg Vars. (line 6)
+* variables, local, in macros: Typeof. (line 42)
+* variadic macros: Variadic Macros. (line 6)
+* VAX calling convention: Interoperation. (line 226)
+* VAX options: VAX Options. (line 6)
+* VAXCRTL: VMS Misc. (line 16)
+* VLAs: Variable Length. (line 6)
+* VMS and case sensitivity: VMS Misc. (line 27)
+* VMS and include files: Include Files and VMS.
+ (line 6)
+* void pointers, arithmetic: Pointer Arith. (line 6)
+* void, size of pointer to: Pointer Arith. (line 6)
+* volatile access: Volatiles. (line 6)
+* volatile applied to function: Function Attributes. (line 6)
+* volatile read: Volatiles. (line 6)
+* volatile write: Volatiles. (line 6)
+* vtable: Vague Linkage. (line 28)
+* warning for comparison of signed and unsigned values: Warning Options.
+ (line 634)
+* warning for overloaded virtual fn: C++ Dialect Options. (line 344)
+* warning for reordering of member initializers <1>: Warning Options.
+ (line 386)
+* warning for reordering of member initializers: C++ Dialect Options.
+ (line 272)
+* warning for synthesized methods: C++ Dialect Options. (line 374)
+* warning for unknown pragmas: Warning Options. (line 390)
+* warning messages: Warning Options. (line 6)
+* warnings from system headers: Warning Options. (line 416)
+* warnings vs errors: Warnings and Errors. (line 6)
+* weak attribute: Function Attributes. (line 267)
+* whitespace: Incompatibilities. (line 136)
+* X in constraint: Simple Constraints. (line 112)
+* X3.159-1989: Standards. (line 6)
+* x86-64 Options: i386 and x86-64 Options.
+ (line 6)
+* Xstormy16 Options: Xstormy16 Options. (line 6)
+* Xtensa Options: Xtensa Options. (line 6)
+* zero division on 88k: M88K Options. (line 123)
+* zero-length arrays: Zero Length. (line 6)
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Preprocessor Options, Next: Assembler Options, Prev: Optimize Options, Up: Invoking GCC
-
-Options Controlling the Preprocessor
-====================================
-
- These options control the C preprocessor, which is run on each C
-source file before actual compilation.
-
- If you use the `-E' option, nothing is done except preprocessing.
-Some of these options make sense only together with `-E' because they
-cause the preprocessor output to be unsuitable for actual compilation.
-
- You can use `-Wp,OPTION' to bypass the compiler driver and pass
-OPTION directly through to the preprocessor. If OPTION contains
-commas, it is split into multiple options at the commas. However, many
-options are modified, translated or interpreted by the compiler driver
-before being passed to the preprocessor, and `-Wp' forcibly bypasses
-this phase. The preprocessor's direct interface is undocumented and
-subject to change, so whenever possible you should avoid using `-Wp'
-and let the driver handle the options instead.
-
-`-D NAME'
- Predefine NAME as a macro, with definition `1'.
-
-`-D NAME=DEFINITION'
- Predefine NAME as a macro, with definition DEFINITION. There are
- no restrictions on the contents of DEFINITION, but if you are
- invoking the preprocessor from a shell or shell-like program you
- may need to use the shell's quoting syntax to protect characters
- such as spaces that have a meaning in the shell syntax.
-
- If you wish to define a function-like macro on the command line,
- write its argument list with surrounding parentheses before the
- equals sign (if any). Parentheses are meaningful to most shells,
- so you will need to quote the option. With `sh' and `csh',
- `-D'NAME(ARGS...)=DEFINITION'' works.
-
- `-D' and `-U' options are processed in the order they are given on
- the command line. All `-imacros FILE' and `-include FILE' options
- are processed after all `-D' and `-U' options.
-
-`-U NAME'
- Cancel any previous definition of NAME, either built in or
- provided with a `-D' option.
-
-`-undef'
- Do not predefine any system-specific macros. The common predefined
- macros remain defined.
-
-`-I DIR'
- Add the directory DIR to the list of directories to be searched
- for header files. Directories named by `-I' are searched before
- the standard system include directories.
-
- It is dangerous to specify a standard system include directory in
- an `-I' option. This defeats the special treatment of system
- headers . It can also defeat the repairs to buggy system headers
- which GCC makes when it is installed.
-
-`-o FILE'
- Write output to FILE. This is the same as specifying FILE as the
- second non-option argument to `cpp'. `gcc' has a different
- interpretation of a second non-option argument, so you must use
- `-o' to specify the output file.
-
-`-Wall'
- Turns on all optional warnings which are desirable for normal
- code. At present this is `-Wcomment' and `-Wtrigraphs'. Note that
- many of the preprocessor's warnings are on by default and have no
- options to control them.
-
-`-Wcomment'
-`-Wcomments'
- Warn whenever a comment-start sequence `/*' appears in a `/*'
- comment, or whenever a backslash-newline appears in a `//' comment.
- (Both forms have the same effect.)
-
-`-Wtrigraphs'
- Warn if any trigraphs are encountered. This option used to take
- effect only if `-trigraphs' was also specified, but now works
- independently. Warnings are not given for trigraphs within
- comments, as they do not affect the meaning of the program.
-
-`-Wtraditional'
- Warn about certain constructs that behave differently in
- traditional and ISO C. Also warn about ISO C constructs that have
- no traditional C equivalent, and problematic constructs which
- should be avoided.
-
-`-Wimport'
- Warn the first time `#import' is used.
-
-`-Wundef'
- Warn whenever an identifier which is not a macro is encountered in
- an `#if' directive, outside of `defined'. Such identifiers are
- replaced with zero.
-
-`-Werror'
- Make all warnings into hard errors. Source code which triggers
- warnings will be rejected.
-
-`-Wsystem-headers'
- Issue warnings for code in system headers. These are normally
- unhelpful in finding bugs in your own code, therefore suppressed.
- If you are responsible for the system library, you may want to see
- them.
-
-`-w'
- Suppress all warnings, including those which GNU CPP issues by
- default.
-
-`-pedantic'
- Issue all the mandatory diagnostics listed in the C standard.
- Some of them are left out by default, since they trigger
- frequently on harmless code.
-
-`-pedantic-errors'
- Issue all the mandatory diagnostics, and make all mandatory
- diagnostics into errors. This includes mandatory diagnostics that
- GCC issues without `-pedantic' but treats as warnings.
-
-`-M'
- Instead of outputting the result of preprocessing, output a rule
- suitable for `make' describing the dependencies of the main source
- file. The preprocessor outputs one `make' rule containing the
- object file name for that source file, a colon, and the names of
- all the included files, including those coming from `-include' or
- `-imacros' command line options.
-
- Unless specified explicitly (with `-MT' or `-MQ'), the object file
- name consists of the basename of the source file with any suffix
- replaced with object file suffix. If there are many included
- files then the rule is split into several lines using `\'-newline.
- The rule has no commands.
-
- This option does not suppress the preprocessor's debug output,
- such as `-dM'. To avoid mixing such debug output with the
- dependency rules you should explicitly specify the dependency
- output file with `-MF', or use an environment variable like
- `DEPENDENCIES_OUTPUT' (*note DEPENDENCIES_OUTPUT::). Debug output
- will still be sent to the regular output stream as normal.
-
- Passing `-M' to the driver implies `-E'.
-
-`-MM'
- Like `-M' but do not mention header files that are found in system
- header directories, nor header files that are included, directly
- or indirectly, from such a header.
-
- This implies that the choice of angle brackets or double quotes in
- an `#include' directive does not in itself determine whether that
- header will appear in `-MM' dependency output. This is a slight
- change in semantics from GCC versions 3.0 and earlier.
-
-`-MF FILE'
- When used with `-M' or `-MM', specifies a file to write the
- dependencies to. If no `-MF' switch is given the preprocessor
- sends the rules to the same place it would have sent preprocessed
- output.
-
- When used with the driver options `-MD' or `-MMD', `-MF' overrides
- the default dependency output file.
-
-`-MG'
- When used with `-M' or `-MM', `-MG' says to treat missing header
- files as generated files and assume they live in the same
- directory as the source file. It suppresses preprocessed output,
- as a missing header file is ordinarily an error.
-
- This feature is used in automatic updating of makefiles.
-
-`-MP'
- This option instructs CPP to add a phony target for each dependency
- other than the main file, causing each to depend on nothing. These
- dummy rules work around errors `make' gives if you remove header
- files without updating the `Makefile' to match.
-
- This is typical output:
-
- test.o: test.c test.h
-
- test.h:
-
-`-MT TARGET'
- Change the target of the rule emitted by dependency generation. By
- default CPP takes the name of the main input file, including any
- path, deletes any file suffix such as `.c', and appends the
- platform's usual object suffix. The result is the target.
-
- An `-MT' option will set the target to be exactly the string you
- specify. If you want multiple targets, you can specify them as a
- single argument to `-MT', or use multiple `-MT' options.
-
- For example, `-MT '$(objpfx)foo.o'' might give
-
- $(objpfx)foo.o: foo.c
-
-`-MQ TARGET'
- Same as `-MT', but it quotes any characters which are special to
- Make. `-MQ '$(objpfx)foo.o'' gives
-
- $$(objpfx)foo.o: foo.c
-
- The default target is automatically quoted, as if it were given
- with `-MQ'.
-
-`-MD'
- `-MD' is equivalent to `-M -MF FILE', except that `-E' is not
- implied. The driver determines FILE based on whether an `-o'
- option is given. If it is, the driver uses its argument but with
- a suffix of `.d', otherwise it take the basename of the input file
- and applies a `.d' suffix.
-
- If `-MD' is used in conjunction with `-E', any `-o' switch is
- understood to specify the dependency output file (but *note
- -MF::), but if used without `-E', each `-o' is understood to
- specify a target object file.
-
- Since `-E' is not implied, `-MD' can be used to generate a
- dependency output file as a side-effect of the compilation process.
-
-`-MMD'
- Like `-MD' except mention only user header files, not system
- -header files.
-
-`-x c'
-`-x c++'
-`-x objective-c'
-`-x assembler-with-cpp'
- Specify the source language: C, C++, Objective-C, or assembly.
- This has nothing to do with standards conformance or extensions;
- it merely selects which base syntax to expect. If you give none
- of these options, cpp will deduce the language from the extension
- of the source file: `.c', `.cc', `.m', or `.S'. Some other common
- extensions for C++ and assembly are also recognized. If cpp does
- not recognize the extension, it will treat the file as C; this is
- the most generic mode.
-
- *Note:* Previous versions of cpp accepted a `-lang' option which
- selected both the language and the standards conformance level.
- This option has been removed, because it conflicts with the `-l'
- option.
-
-`-std=STANDARD'
-`-ansi'
- Specify the standard to which the code should conform. Currently
- cpp only knows about the standards for C; other language standards
- will be added in the future.
-
- STANDARD may be one of:
- `iso9899:1990'
- `c89'
- The ISO C standard from 1990. `c89' is the customary
- shorthand for this version of the standard.
-
- The `-ansi' option is equivalent to `-std=c89'.
-
- `iso9899:199409'
- The 1990 C standard, as amended in 1994.
-
- `iso9899:1999'
- `c99'
- `iso9899:199x'
- `c9x'
- The revised ISO C standard, published in December 1999.
- Before publication, this was known as C9X.
-
- `gnu89'
- The 1990 C standard plus GNU extensions. This is the default.
-
- `gnu99'
- `gnu9x'
- The 1999 C standard plus GNU extensions.
-
-`-I-'
- Split the include path. Any directories specified with `-I'
- options before `-I-' are searched only for headers requested with
- `#include "FILE"'; they are not searched for `#include <FILE>'.
- If additional directories are specified with `-I' options after
- the `-I-', those directories are searched for all `#include'
- directives.
-
- In addition, `-I-' inhibits the use of the directory of the current
- file directory as the first search directory for `#include "FILE"'.
-
-`-nostdinc'
- Do not search the standard system directories for header files.
- Only the directories you have specified with `-I' options (and the
- directory of the current file, if appropriate) are searched.
-
-`-nostdinc++'
- Do not search for header files in the C++-specific standard
- directories, but do still search the other standard directories.
- (This option is used when building the C++ library.)
-
-`-include FILE'
- Process FILE as if `#include "file"' appeared as the first line of
- the primary source file. However, the first directory searched
- for FILE is the preprocessor's working directory _instead of_ the
- directory containing the main source file. If not found there, it
- is searched for in the remainder of the `#include "..."' search
- chain as normal.
-
- If multiple `-include' options are given, the files are included
- in the order they appear on the command line.
-
-`-imacros FILE'
- Exactly like `-include', except that any output produced by
- scanning FILE is thrown away. Macros it defines remain defined.
- This allows you to acquire all the macros from a header without
- also processing its declarations.
-
- All files specified by `-imacros' are processed before all files
- specified by `-include'.
-
-`-idirafter DIR'
- Search DIR for header files, but do it _after_ all directories
- specified with `-I' and the standard system directories have been
- exhausted. DIR is treated as a system include directory.
-
-`-iprefix PREFIX'
- Specify PREFIX as the prefix for subsequent `-iwithprefix'
- options. If the prefix represents a directory, you should include
- the final `/'.
-
-`-iwithprefix DIR'
-`-iwithprefixbefore DIR'
- Append DIR to the prefix specified previously with `-iprefix', and
- add the resulting directory to the include search path.
- `-iwithprefixbefore' puts it in the same place `-I' would;
- `-iwithprefix' puts it where `-idirafter' would.
-
- Use of these options is discouraged.
-
-`-isystem DIR'
- Search DIR for header files, after all directories specified by
- `-I' but before the standard system directories. Mark it as a
- system directory, so that it gets the same special treatment as is
- applied to the standard system directories.
-
-`-fpreprocessed'
- Indicate to the preprocessor that the input file has already been
- preprocessed. This suppresses things like macro expansion,
- trigraph conversion, escaped newline splicing, and processing of
- most directives. The preprocessor still recognizes and removes
- comments, so that you can pass a file preprocessed with `-C' to
- the compiler without problems. In this mode the integrated
- preprocessor is little more than a tokenizer for the front ends.
-
- `-fpreprocessed' is implicit if the input file has one of the
- extensions `.i', `.ii' or `.mi'. These are the extensions that
- GCC uses for preprocessed files created by `-save-temps'.
-
-`-ftabstop=WIDTH'
- Set the distance between tab stops. This helps the preprocessor
- report correct column numbers in warnings or errors, even if tabs
- appear on the line. If the value is less than 1 or greater than
- 100, the option is ignored. The default is 8.
-
-`-fno-show-column'
- Do not print column numbers in diagnostics. This may be necessary
- if diagnostics are being scanned by a program that does not
- understand the column numbers, such as `dejagnu'.
-
-`-A PREDICATE=ANSWER'
- Make an assertion with the predicate PREDICATE and answer ANSWER.
- This form is preferred to the older form `-A PREDICATE(ANSWER)',
- which is still supported, because it does not use shell special
- characters.
-
-`-A -PREDICATE=ANSWER'
- Cancel an assertion with the predicate PREDICATE and answer ANSWER.
-
-`-A-'
- Cancel all predefined assertions and all assertions preceding it on
- the command line. Also, undefine all predefined macros and all
- macros preceding it on the command line. (This is a historical
- wart and may change in the future.)
-
-`-dCHARS'
- CHARS is a sequence of one or more of the following characters,
- and must not be preceded by a space. Other characters are
- interpreted by the compiler proper, or reserved for future
- versions of GCC, and so are silently ignored. If you specify
- characters whose behavior conflicts, the result is undefined.
-
- `M'
- Instead of the normal output, generate a list of `#define'
- directives for all the macros defined during the execution of
- the preprocessor, including predefined macros. This gives
- you a way of finding out what is predefined in your version
- of the preprocessor. Assuming you have no file `foo.h', the
- command
-
- touch foo.h; cpp -dM foo.h
-
- will show all the predefined macros.
-
- `D'
- Like `M' except in two respects: it does _not_ include the
- predefined macros, and it outputs _both_ the `#define'
- directives and the result of preprocessing. Both kinds of
- output go to the standard output file.
-
- `N'
- Like `D', but emit only the macro names, not their expansions.
-
- `I'
- Output `#include' directives in addition to the result of
- preprocessing.
-
-`-P'
- Inhibit generation of linemarkers in the output from the
- preprocessor. This might be useful when running the preprocessor
- on something that is not C code, and will be sent to a program
- which might be confused by the linemarkers.
-
-`-C'
- Do not discard comments. All comments are passed through to the
- output file, except for comments in processed directives, which
- are deleted along with the directive.
-
- You should be prepared for side effects when using `-C'; it causes
- the preprocessor to treat comments as tokens in their own right.
- For example, comments appearing at the start of what would be a
- directive line have the effect of turning that line into an
- ordinary source line, since the first token on the line is no
- longer a `#'.
-
-`-gcc'
- Define the macros __GNUC__, __GNUC_MINOR__ and
- __GNUC_PATCHLEVEL__. These are defined automatically when you use
- `gcc -E'; you can turn them off in that case with `-no-gcc'.
-
-`-traditional'
- Try to imitate the behavior of old-fashioned C, as opposed to ISO
- C.
-
-`-trigraphs'
- Process trigraph sequences. These are three-character sequences,
- all starting with `??', that are defined by ISO C to stand for
- single characters. For example, `??/' stands for `\', so `'??/n''
- is a character constant for a newline. By default, GCC ignores
- trigraphs, but in standard-conforming modes it converts them. See
- the `-std' and `-ansi' options.
-
- The nine trigraphs and their replacements are
-
- Trigraph: ??( ??) ??< ??> ??= ??/ ??' ??! ??-
- Replacement: [ ] { } # \ ^ | ~
-
-`-remap'
- Enable special code to work around file systems which only permit
- very short file names, such as MS-DOS.
-
-`-$'
- Forbid the use of `$' in identifiers. The C standard allows
- implementations to define extra characters that can appear in
- identifiers. By default GNU CPP permits `$', a common extension.
-
-`-h'
-`--help'
-`--target-help'
- Print text describing all the command line options instead of
- preprocessing anything.
-
-`-v'
- Verbose mode. Print out GNU CPP's version number at the beginning
- of execution, and report the final form of the include path.
-
-`-H'
- Print the name of each header file used, in addition to other
- normal activities. Each name is indented to show how deep in the
- `#include' stack it is.
-
-`-version'
-`--version'
- Print out GNU CPP's version number. With one dash, proceed to
- preprocess as normal. With two dashes, exit immediately.
-
-\1f
-File: gcc.info, Node: Assembler Options, Next: Link Options, Prev: Preprocessor Options, Up: Invoking GCC
-
-Passing Options to the Assembler
-================================
-
- You can pass options to the assembler.
-
-`-Wa,OPTION'
- Pass OPTION as an option to the assembler. If OPTION contains
- commas, it is split into multiple options at the commas.
-
-\1f
-File: gcc.info, Node: Link Options, Next: Directory Options, Prev: Assembler Options, Up: Invoking GCC
-
-Options for Linking
-===================
-
- These options come into play when the compiler links object files
-into an executable output file. They are meaningless if the compiler is
-not doing a link step.
-
-`OBJECT-FILE-NAME'
- A file name that does not end in a special recognized suffix is
- considered to name an object file or library. (Object files are
- distinguished from libraries by the linker according to the file
- contents.) If linking is done, these object files are used as
- input to the linker.
-
-`-c'
-`-S'
-`-E'
- If any of these options is used, then the linker is not run, and
- object file names should not be used as arguments. *Note Overall
- Options::.
-
-`-lLIBRARY'
-`-l LIBRARY'
- Search the library named LIBRARY when linking. (The second
- alternative with the library as a separate argument is only for
- POSIX compliance and is not recommended.)
-
- It makes a difference where in the command you write this option;
- the linker searches and processes libraries and object files in
- the order they are specified. Thus, `foo.o -lz bar.o' searches
- library `z' after file `foo.o' but before `bar.o'. If `bar.o'
- refers to functions in `z', those functions may not be loaded.
-
- The linker searches a standard list of directories for the library,
- which is actually a file named `libLIBRARY.a'. The linker then
- uses this file as if it had been specified precisely by name.
-
- The directories searched include several standard system
- directories plus any that you specify with `-L'.
-
- Normally the files found this way are library files--archive files
- whose members are object files. The linker handles an archive
- file by scanning through it for members which define symbols that
- have so far been referenced but not defined. But if the file that
- is found is an ordinary object file, it is linked in the usual
- fashion. The only difference between using an `-l' option and
- specifying a file name is that `-l' surrounds LIBRARY with `lib'
- and `.a' and searches several directories.
-
-`-lobjc'
- You need this special case of the `-l' option in order to link an
- Objective-C program.
-
-`-nostartfiles'
- Do not use the standard system startup files when linking. The
- standard system libraries are used normally, unless `-nostdlib' or
- `-nodefaultlibs' is used.
-
-`-nodefaultlibs'
- Do not use the standard system libraries when linking. Only the
- libraries you specify will be passed to the linker. The standard
- startup files are used normally, unless `-nostartfiles' is used.
- The compiler may generate calls to memcmp, memset, and memcpy for
- System V (and ISO C) environments or to bcopy and bzero for BSD
- environments. These entries are usually resolved by entries in
- libc. These entry points should be supplied through some other
- mechanism when this option is specified.
-
-`-nostdlib'
- Do not use the standard system startup files or libraries when
- linking. No startup files and only the libraries you specify will
- be passed to the linker. The compiler may generate calls to
- memcmp, memset, and memcpy for System V (and ISO C) environments
- or to bcopy and bzero for BSD environments. These entries are
- usually resolved by entries in libc. These entry points should be
- supplied through some other mechanism when this option is
- specified.
-
- One of the standard libraries bypassed by `-nostdlib' and
- `-nodefaultlibs' is `libgcc.a', a library of internal subroutines
- that GCC uses to overcome shortcomings of particular machines, or
- special needs for some languages. (*Note Interfacing to GCC
- Output: (gccint)Interface, for more discussion of `libgcc.a'.) In
- most cases, you need `libgcc.a' even when you want to avoid other
- standard libraries. In other words, when you specify `-nostdlib'
- or `-nodefaultlibs' you should usually specify `-lgcc' as well.
- This ensures that you have no unresolved references to internal GCC
- library subroutines. (For example, `__main', used to ensure C++
- constructors will be called; *note `collect2': (gccint)Collect2..)
-
-`-s'
- Remove all symbol table and relocation information from the
- executable.
-
-`-static'
- On systems that support dynamic linking, this prevents linking
- with the shared libraries. On other systems, this option has no
- effect.
-
-`-shared'
- Produce a shared object which can then be linked with other
- objects to form an executable. Not all systems support this
- option. For predictable results, you must also specify the same
- set of options that were used to generate code (`-fpic', `-fPIC',
- or model suboptions) when you specify this option.(1)
-
-`-shared-libgcc'
-`-static-libgcc'
- On systems that provide `libgcc' as a shared library, these options
- force the use of either the shared or static version respectively.
- If no shared version of `libgcc' was built when the compiler was
- configured, these options have no effect.
-
- There are several situations in which an application should use the
- shared `libgcc' instead of the static version. The most common of
- these is when the application wishes to throw and catch exceptions
- across different shared libraries. In that case, each of the
- libraries as well as the application itself should use the shared
- `libgcc'.
-
- Therefore, the G++ and GCJ drivers automatically add
- `-shared-libgcc' whenever you build a shared library or a main
- executable, because C++ and Java programs typically use
- exceptions, so this is the right thing to do.
-
- If, instead, you use the GCC driver to create shared libraries,
- you may find that they will not always be linked with the shared
- `libgcc'. If GCC finds, at its configuration time, that you have
- a GNU linker that does not support option `--eh-frame-hdr', it
- will link the shared version of `libgcc' into shared libraries by
- default. Otherwise, it will take advantage of the linker and
- optimize away the linking with the shared version of `libgcc',
- linking with the static version of libgcc by default. This allows
- exceptions to propagate through such shared libraries, without
- incurring relocation costs at library load time.
-
- However, if a library or main executable is supposed to throw or
- catch exceptions, you must link it using the G++ or GCJ driver, as
- appropriate for the languages used in the program, or using the
- option `-shared-libgcc', such that it is linked with the shared
- `libgcc'.
-
-`-symbolic'
- Bind references to global symbols when building a shared object.
- Warn about any unresolved references (unless overridden by the
- link editor option `-Xlinker -z -Xlinker defs'). Only a few
- systems support this option.
-
-`-Xlinker OPTION'
- Pass OPTION as an option to the linker. You can use this to
- supply system-specific linker options which GCC does not know how
- to recognize.
-
- If you want to pass an option that takes an argument, you must use
- `-Xlinker' twice, once for the option and once for the argument.
- For example, to pass `-assert definitions', you must write
- `-Xlinker -assert -Xlinker definitions'. It does not work to write
- `-Xlinker "-assert definitions"', because this passes the entire
- string as a single argument, which is not what the linker expects.
-
-`-Wl,OPTION'
- Pass OPTION as an option to the linker. If OPTION contains
- commas, it is split into multiple options at the commas.
-
-`-u SYMBOL'
- Pretend the symbol SYMBOL is undefined, to force linking of
- library modules to define it. You can use `-u' multiple times with
- different symbols to force loading of additional library modules.
-
- ---------- Footnotes ----------
-
- (1) On some systems, `gcc -shared' needs to build supplementary stub
-code for constructors to work. On multi-libbed systems, `gcc -shared'
-must select the correct support libraries to link against. Failing to
-supply the correct flags may lead to subtle defects. Supplying them in
-cases where they are not necessary is innocuous.
-
-\1f
-File: gcc.info, Node: Directory Options, Next: Spec Files, Prev: Link Options, Up: Invoking GCC
-
-Options for Directory Search
-============================
-
- These options specify directories to search for header files, for
-libraries and for parts of the compiler:
-
-`-IDIR'
- Add the directory DIR to the head of the list of directories to be
- searched for header files. This can be used to override a system
- header file, substituting your own version, since these
- directories are searched before the system header file
- directories. However, you should not use this option to add
- directories that contain vendor-supplied system header files (use
- `-isystem' for that). If you use more than one `-I' option, the
- directories are scanned in left-to-right order; the standard
- system directories come after.
-
- If a standard system include directory, or a directory specified
- with `-isystem', is also specified with `-I', the `-I' option will
- be ignored. The directory will still be searched but as a system
- directory at its normal position in the system include chain.
- This is to ensure that GCC's procedure to fix buggy system headers
- and the ordering for the include_next directive are not
- inadvertantly changed. If you really need to change the search
- order for system directories, use the `-nostdinc' and/or
- `-isystem' options.
-
-`-I-'
- Any directories you specify with `-I' options before the `-I-'
- option are searched only for the case of `#include "FILE"'; they
- are not searched for `#include <FILE>'.
-
- If additional directories are specified with `-I' options after
- the `-I-', these directories are searched for all `#include'
- directives. (Ordinarily _all_ `-I' directories are used this way.)
-
- In addition, the `-I-' option inhibits the use of the current
- directory (where the current input file came from) as the first
- search directory for `#include "FILE"'. There is no way to
- override this effect of `-I-'. With `-I.' you can specify
- searching the directory which was current when the compiler was
- invoked. That is not exactly the same as what the preprocessor
- does by default, but it is often satisfactory.
-
- `-I-' does not inhibit the use of the standard system directories
- for header files. Thus, `-I-' and `-nostdinc' are independent.
-
-`-LDIR'
- Add directory DIR to the list of directories to be searched for
- `-l'.
-
-`-BPREFIX'
- This option specifies where to find the executables, libraries,
- include files, and data files of the compiler itself.
-
- The compiler driver program runs one or more of the subprograms
- `cpp', `cc1', `as' and `ld'. It tries PREFIX as a prefix for each
- program it tries to run, both with and without `MACHINE/VERSION/'
- (*note Target Options::).
-
- For each subprogram to be run, the compiler driver first tries the
- `-B' prefix, if any. If that name is not found, or if `-B' was
- not specified, the driver tries two standard prefixes, which are
- `/usr/lib/gcc/' and `/usr/local/lib/gcc-lib/'. If neither of
- those results in a file name that is found, the unmodified program
- name is searched for using the directories specified in your
- `PATH' environment variable.
-
- The compiler will check to see if the path provided by the `-B'
- refers to a directory, and if necessary it will add a directory
- separator character at the end of the path.
-
- `-B' prefixes that effectively specify directory names also apply
- to libraries in the linker, because the compiler translates these
- options into `-L' options for the linker. They also apply to
- includes files in the preprocessor, because the compiler
- translates these options into `-isystem' options for the
- preprocessor. In this case, the compiler appends `include' to the
- prefix.
-
- The run-time support file `libgcc.a' can also be searched for using
- the `-B' prefix, if needed. If it is not found there, the two
- standard prefixes above are tried, and that is all. The file is
- left out of the link if it is not found by those means.
-
- Another way to specify a prefix much like the `-B' prefix is to use
- the environment variable `GCC_EXEC_PREFIX'. *Note Environment
- Variables::.
-
- As a special kludge, if the path provided by `-B' is
- `[dir/]stageN/', where N is a number in the range 0 to 9, then it
- will be replaced by `[dir/]include'. This is to help with
- boot-strapping the compiler.
-
-`-specs=FILE'
- Process FILE after the compiler reads in the standard `specs'
- file, in order to override the defaults that the `gcc' driver
- program uses when determining what switches to pass to `cc1',
- `cc1plus', `as', `ld', etc. More than one `-specs=FILE' can be
- specified on the command line, and they are processed in order,
- from left to right.
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: Spec Files, Next: Target Options, Prev: Directory Options, Up: Invoking GCC
-
-Specifying subprocesses and the switches to pass to them
-========================================================
-
- `gcc' is a driver program. It performs its job by invoking a
-sequence of other programs to do the work of compiling, assembling and
-linking. GCC interprets its command-line parameters and uses these to
-deduce which programs it should invoke, and which command-line options
-it ought to place on their command lines. This behavior is controlled
-by "spec strings". In most cases there is one spec string for each
-program that GCC can invoke, but a few programs have multiple spec
-strings to control their behavior. The spec strings built into GCC can
-be overridden by using the `-specs=' command-line switch to specify a
-spec file.
-
- "Spec files" are plaintext files that are used to construct spec
-strings. They consist of a sequence of directives separated by blank
-lines. The type of directive is determined by the first non-whitespace
-character on the line and it can be one of the following:
-
-`%COMMAND'
- Issues a COMMAND to the spec file processor. The commands that can
- appear here are:
-
- `%include <FILE>'
- Search for FILE and insert its text at the current point in
- the specs file.
-
- `%include_noerr <FILE>'
- Just like `%include', but do not generate an error message if
- the include file cannot be found.
-
- `%rename OLD_NAME NEW_NAME'
- Rename the spec string OLD_NAME to NEW_NAME.
-
-
-`*[SPEC_NAME]:'
- This tells the compiler to create, override or delete the named
- spec string. All lines after this directive up to the next
- directive or blank line are considered to be the text for the spec
- string. If this results in an empty string then the spec will be
- deleted. (Or, if the spec did not exist, then nothing will
- happened.) Otherwise, if the spec does not currently exist a new
- spec will be created. If the spec does exist then its contents
- will be overridden by the text of this directive, unless the first
- character of that text is the `+' character, in which case the
- text will be appended to the spec.
-
-`[SUFFIX]:'
- Creates a new `[SUFFIX] spec' pair. All lines after this directive
- and up to the next directive or blank line are considered to make
- up the spec string for the indicated suffix. When the compiler
- encounters an input file with the named suffix, it will processes
- the spec string in order to work out how to compile that file.
- For example:
-
- .ZZ:
- z-compile -input %i
-
- This says that any input file whose name ends in `.ZZ' should be
- passed to the program `z-compile', which should be invoked with the
- command-line switch `-input' and with the result of performing the
- `%i' substitution. (See below.)
-
- As an alternative to providing a spec string, the text that
- follows a suffix directive can be one of the following:
-
- `@LANGUAGE'
- This says that the suffix is an alias for a known LANGUAGE.
- This is similar to using the `-x' command-line switch to GCC
- to specify a language explicitly. For example:
-
- .ZZ:
- @c++
-
- Says that .ZZ files are, in fact, C++ source files.
-
- `#NAME'
- This causes an error messages saying:
-
- NAME compiler not installed on this system.
-
- GCC already has an extensive list of suffixes built into it. This
- directive will add an entry to the end of the list of suffixes, but
- since the list is searched from the end backwards, it is
- effectively possible to override earlier entries using this
- technique.
-
-
- GCC has the following spec strings built into it. Spec files can
-override these strings or create their own. Note that individual
-targets can also add their own spec strings to this list.
-
- asm Options to pass to the assembler
- asm_final Options to pass to the assembler post-processor
- cpp Options to pass to the C preprocessor
- cc1 Options to pass to the C compiler
- cc1plus Options to pass to the C++ compiler
- endfile Object files to include at the end of the link
- link Options to pass to the linker
- lib Libraries to include on the command line to the linker
- libgcc Decides which GCC support library to pass to the linker
- linker Sets the name of the linker
- predefines Defines to be passed to the C preprocessor
- signed_char Defines to pass to CPP to say whether `char' is signed
- by default
- startfile Object files to include at the start of the link
-
- Here is a small example of a spec file:
-
- %rename lib old_lib
-
- *lib:
- --start-group -lgcc -lc -leval1 --end-group %(old_lib)
-
- This example renames the spec called `lib' to `old_lib' and then
-overrides the previous definition of `lib' with a new one. The new
-definition adds in some extra command-line options before including the
-text of the old definition.
-
- "Spec strings" are a list of command-line options to be passed to
-their corresponding program. In addition, the spec strings can contain
-`%'-prefixed sequences to substitute variable text or to conditionally
-insert text into the command line. Using these constructs it is
-possible to generate quite complex command lines.
-
- Here is a table of all defined `%'-sequences for spec strings. Note
-that spaces are not generated automatically around the results of
-expanding these sequences. Therefore you can concatenate them together
-or combine them with constant text in a single argument.
-
-`%%'
- Substitute one `%' into the program name or argument.
-
-`%i'
- Substitute the name of the input file being processed.
-
-`%b'
- Substitute the basename of the input file being processed. This
- is the substring up to (and not including) the last period and not
- including the directory.
-
-`%B'
- This is the same as `%b', but include the file suffix (text after
- the last period).
-
-`%d'
- Marks the argument containing or following the `%d' as a temporary
- file name, so that that file will be deleted if GCC exits
- successfully. Unlike `%g', this contributes no text to the
- argument.
-
-`%gSUFFIX'
- Substitute a file name that has suffix SUFFIX and is chosen once
- per compilation, and mark the argument in the same way as `%d'.
- To reduce exposure to denial-of-service attacks, the file name is
- now chosen in a way that is hard to predict even when previously
- chosen file names are known. For example, `%g.s ... %g.o ... %g.s'
- might turn into `ccUVUUAU.s ccXYAXZ12.o ccUVUUAU.s'. SUFFIX
- matches the regexp `[.A-Za-z]*' or the special string `%O', which
- is treated exactly as if `%O' had been preprocessed. Previously,
- `%g' was simply substituted with a file name chosen once per
- compilation, without regard to any appended suffix (which was
- therefore treated just like ordinary text), making such attacks
- more likely to succeed.
-
-`%uSUFFIX'
- Like `%g', but generates a new temporary file name even if
- `%uSUFFIX' was already seen.
-
-`%USUFFIX'
- Substitutes the last file name generated with `%uSUFFIX',
- generating a new one if there is no such last file name. In the
- absence of any `%uSUFFIX', this is just like `%gSUFFIX', except
- they don't share the same suffix _space_, so `%g.s ... %U.s ...
- %g.s ... %U.s' would involve the generation of two distinct file
- names, one for each `%g.s' and another for each `%U.s'.
- Previously, `%U' was simply substituted with a file name chosen
- for the previous `%u', without regard to any appended suffix.
-
-`%jSUFFIX'
- Substitutes the name of the `HOST_BIT_BUCKET', if any, and if it is
- writable, and if save-temps is off; otherwise, substitute the name
- of a temporary file, just like `%u'. This temporary file is not
- meant for communication between processes, but rather as a junk
- disposal mechanism.
-
-`%.SUFFIX'
- Substitutes .SUFFIX for the suffixes of a matched switch's args
- when it is subsequently output with `%*'. SUFFIX is terminated by
- the next space or %.
-
-`%w'
- Marks the argument containing or following the `%w' as the
- designated output file of this compilation. This puts the argument
- into the sequence of arguments that `%o' will substitute later.
-
-`%o'
- Substitutes the names of all the output files, with spaces
- automatically placed around them. You should write spaces around
- the `%o' as well or the results are undefined. `%o' is for use in
- the specs for running the linker. Input files whose names have no
- recognized suffix are not compiled at all, but they are included
- among the output files, so they will be linked.
-
-`%O'
- Substitutes the suffix for object files. Note that this is
- handled specially when it immediately follows `%g, %u, or %U',
- because of the need for those to form complete file names. The
- handling is such that `%O' is treated exactly as if it had already
- been substituted, except that `%g, %u, and %U' do not currently
- support additional SUFFIX characters following `%O' as they would
- following, for example, `.o'.
-
-`%p'
- Substitutes the standard macro predefinitions for the current
- target machine. Use this when running `cpp'.
-
-`%P'
- Like `%p', but puts `__' before and after the name of each
- predefined macro, except for macros that start with `__' or with
- `_L', where L is an uppercase letter. This is for ISO C.
-
-`%I'
- Substitute a `-iprefix' option made from `GCC_EXEC_PREFIX'.
-
-`%s'
- Current argument is the name of a library or startup file of some
- sort. Search for that file in a standard list of directories and
- substitute the full name found.
-
-`%eSTR'
- Print STR as an error message. STR is terminated by a newline.
- Use this when inconsistent options are detected.
-
-`%|'
- Output `-' if the input for the current command is coming from a
- pipe.
-
-`%(NAME)'
- Substitute the contents of spec string NAME at this point.
-
-`%[NAME]'
- Like `%(...)' but put `__' around `-D' arguments.
-
-`%x{OPTION}'
- Accumulate an option for `%X'.
-
-`%X'
- Output the accumulated linker options specified by `-Wl' or a `%x'
- spec string.
-
-`%Y'
- Output the accumulated assembler options specified by `-Wa'.
-
-`%Z'
- Output the accumulated preprocessor options specified by `-Wp'.
-
-`%v1'
- Substitute the major version number of GCC. (For version 2.9.5,
- this is 2.)
-
-`%v2'
- Substitute the minor version number of GCC. (For version 2.9.5,
- this is 9.)
-
-`%v3'
- Substitute the patch level number of GCC. (For version 2.9.5,
- this is 5.)
-
-`%a'
- Process the `asm' spec. This is used to compute the switches to
- be passed to the assembler.
-
-`%A'
- Process the `asm_final' spec. This is a spec string for passing
- switches to an assembler post-processor, if such a program is
- needed.
-
-`%l'
- Process the `link' spec. This is the spec for computing the
- command line passed to the linker. Typically it will make use of
- the `%L %G %S %D and %E' sequences.
-
-`%D'
- Dump out a `-L' option for each directory that GCC believes might
- contain startup files. If the target supports multilibs then the
- current multilib directory will be prepended to each of these
- paths.
-
-`%M'
- Output the multilib directory with directory separators replaced
- with `_'. If multilib directories are not set, or the multilib
- directory is `.' then this option emits nothing.
-
-`%L'
- Process the `lib' spec. This is a spec string for deciding which
- libraries should be included on the command line to the linker.
-
-`%G'
- Process the `libgcc' spec. This is a spec string for deciding
- which GCC support library should be included on the command line
- to the linker.
-
-`%S'
- Process the `startfile' spec. This is a spec for deciding which
- object files should be the first ones passed to the linker.
- Typically this might be a file named `crt0.o'.
-
-`%E'
- Process the `endfile' spec. This is a spec string that specifies
- the last object files that will be passed to the linker.
-
-`%C'
- Process the `cpp' spec. This is used to construct the arguments
- to be passed to the C preprocessor.
-
-`%c'
- Process the `signed_char' spec. This is intended to be used to
- tell cpp whether a char is signed. It typically has the
- definition:
- %{funsigned-char:-D__CHAR_UNSIGNED__}
-
-`%1'
- Process the `cc1' spec. This is used to construct the options to
- be passed to the actual C compiler (`cc1').
-
-`%2'
- Process the `cc1plus' spec. This is used to construct the options
- to be passed to the actual C++ compiler (`cc1plus').
-
-`%*'
- Substitute the variable part of a matched option. See below.
- Note that each comma in the substituted string is replaced by a
- single space.
-
-`%{`S'}'
- Substitutes the `-S' switch, if that switch was given to GCC. If
- that switch was not specified, this substitutes nothing. Note that
- the leading dash is omitted when specifying this option, and it is
- automatically inserted if the substitution is performed. Thus the
- spec string `%{foo}' would match the command-line option `-foo'
- and would output the command line option `-foo'.
-
-`%W{`S'}'
- Like %{`S'} but mark last argument supplied within as a file to be
- deleted on failure.
-
-`%{`S'*}'
- Substitutes all the switches specified to GCC whose names start
- with `-S', but which also take an argument. This is used for
- switches like `-o', `-D', `-I', etc. GCC considers `-o foo' as
- being one switch whose names starts with `o'. %{o*} would
- substitute this text, including the space. Thus two arguments
- would be generated.
-
-`%{^`S'*}'
- Like %{`S'*}, but don't put a blank between a switch and its
- argument. Thus %{^o*} would only generate one argument, not two.
-
-`%{`S'*&`T'*}'
- Like %{`S'*}, but preserve order of `S' and `T' options (the order
- of `S' and `T' in the spec is not significant). There can be any
- number of ampersand-separated variables; for each the wild card is
- optional. Useful for CPP as `%{D*&U*&A*}'.
-
-`%{<`S'}'
- Remove all occurrences of `-S' from the command line. Note--this
- command is position dependent. `%' commands in the spec string
- before this option will see `-S', `%' commands in the spec string
- after this option will not.
-
-`%{`S'*:`X'}'
- Substitutes `X' if one or more switches whose names start with
- `-S' are specified to GCC. Note that the tail part of the `-S'
- option (i.e. the part matched by the `*') will be substituted for
- each occurrence of `%*' within `X'.
-
-`%{`S':`X'}'
- Substitutes `X', but only if the `-S' switch was given to GCC.
-
-`%{!`S':`X'}'
- Substitutes `X', but only if the `-S' switch was _not_ given to
- GCC.
-
-`%{|`S':`X'}'
- Like %{`S':`X'}, but if no `S' switch, substitute `-'.
-
-`%{|!`S':`X'}'
- Like %{!`S':`X'}, but if there is an `S' switch, substitute `-'.
-
-`%{.`S':`X'}'
- Substitutes `X', but only if processing a file with suffix `S'.
-
-`%{!.`S':`X'}'
- Substitutes `X', but only if _not_ processing a file with suffix
- `S'.
-
-`%{`S'|`P':`X'}'
- Substitutes `X' if either `-S' or `-P' was given to GCC. This may
- be combined with `!' and `.' sequences as well, although they have
- a stronger binding than the `|'. For example a spec string like
- this:
-
- %{.c:-foo} %{!.c:-bar} %{.c|d:-baz} %{!.c|d:-boggle}
-
- will output the following command-line options from the following
- input command-line options:
-
- fred.c -foo -baz
- jim.d -bar -boggle
- -d fred.c -foo -baz -boggle
- -d jim.d -bar -baz -boggle
-
-
- The conditional text `X' in a %{`S':`X'} or %{!`S':`X'} construct
-may contain other nested `%' constructs or spaces, or even newlines.
-They are processed as usual, as described above.
-
- The `-O', `-f', `-m', and `-W' switches are handled specifically in
-these constructs. If another value of `-O' or the negated form of a
-`-f', `-m', or `-W' switch is found later in the command line, the
-earlier switch value is ignored, except with {`S'*} where `S' is just
-one letter, which passes all matching options.
-
- The character `|' at the beginning of the predicate text is used to
-indicate that a command should be piped to the following command, but
-only if `-pipe' is specified.
-
- It is built into GCC which switches take arguments and which do not.
-(You might think it would be useful to generalize this to allow each
-compiler's spec to say which switches take arguments. But this cannot
-be done in a consistent fashion. GCC cannot even decide which input
-files have been specified without knowing which switches take arguments,
-and it must know which input files to compile in order to tell which
-compilers to run).
-
- GCC also knows implicitly that arguments starting in `-l' are to be
-treated as compiler output files, and passed to the linker in their
-proper position among the other output files.
-
-\1f
-File: gcc.info, Node: Target Options, Next: Submodel Options, Prev: Spec Files, Up: Invoking GCC
-
-Specifying Target Machine and Compiler Version
-==============================================
-
- By default, GCC compiles code for the same type of machine that you
-are using. However, it can also be installed as a cross-compiler, to
-compile for some other type of machine. In fact, several different
-configurations of GCC, for different target machines, can be installed
-side by side. Then you specify which one to use with the `-b' option.
-
- In addition, older and newer versions of GCC can be installed side
-by side. One of them (probably the newest) will be the default, but
-you may sometimes wish to use another.
-
-`-b MACHINE'
- The argument MACHINE specifies the target machine for compilation.
- This is useful when you have installed GCC as a cross-compiler.
-
- The value to use for MACHINE is the same as was specified as the
- machine type when configuring GCC as a cross-compiler. For
- example, if a cross-compiler was configured with `configure
- i386v', meaning to compile for an 80386 running System V, then you
- would specify `-b i386v' to run that cross compiler.
-
- When you do not specify `-b', it normally means to compile for the
- same type of machine that you are using.
-
-`-V VERSION'
- The argument VERSION specifies which version of GCC to run. This
- is useful when multiple versions are installed. For example,
- VERSION might be `2.0', meaning to run GCC version 2.0.
-
- The default version, when you do not specify `-V', is the last
- version of GCC that you installed.
-
- The `-b' and `-V' options actually work by controlling part of the
-file name used for the executable files and libraries used for
-compilation. A given version of GCC, for a given target machine, is
-normally kept in the directory `/usr/local/lib/gcc-lib/MACHINE/VERSION'.
-
- Thus, sites can customize the effect of `-b' or `-V' either by
-changing the names of these directories or adding alternate names (or
-symbolic links). If in directory `/usr/local/lib/gcc-lib/' the file
-`80386' is a link to the file `i386v', then `-b 80386' becomes an alias
-for `-b i386v'.
-
- In one respect, the `-b' or `-V' do not completely change to a
-different compiler: the top-level driver program `gcc' that you
-originally invoked continues to run and invoke the other executables
-(preprocessor, compiler per se, assembler and linker) that do the real
-work. However, since no real work is done in the driver program, it
-usually does not matter that the driver program in use is not the one
-for the specified target. It is common for the interface to the other
-executables to change incompatibly between compiler versions, so unless
-the version specified is very close to that of the driver (for example,
-`-V 3.0' with a driver program from GCC version 3.0.1), use of `-V' may
-not work; for example, using `-V 2.95.2' will not work with a driver
-program from GCC 3.0.
-
- The only way that the driver program depends on the target machine is
-in the parsing and handling of special machine-specific options.
-However, this is controlled by a file which is found, along with the
-other executables, in the directory for the specified version and
-target machine. As a result, a single installed driver program adapts
-to any specified target machine, and sufficiently similar compiler
-versions.
-
- The driver program executable does control one significant thing,
-however: the default version and target machine. Therefore, you can
-install different instances of the driver program, compiled for
-different targets or versions, under different names.
-
- For example, if the driver for version 2.0 is installed as `ogcc'
-and that for version 2.1 is installed as `gcc', then the command `gcc'
-will use version 2.1 by default, while `ogcc' will use 2.0 by default.
-However, you can choose either version with either command with the
-`-V' option.
-
-\1f
-File: gcc.info, Node: Submodel Options, Next: Code Gen Options, Prev: Target Options, Up: Invoking GCC
-
-Hardware Models and Configurations
-==================================
-
- Earlier we discussed the standard option `-b' which chooses among
-different installed compilers for completely different target machines,
-such as VAX vs. 68000 vs. 80386.
-
- In addition, each of these target machine types can have its own
-special options, starting with `-m', to choose among various hardware
-models or configurations--for example, 68010 vs 68020, floating
-coprocessor or none. A single installed version of the compiler can
-compile for any model or configuration, according to the options
-specified.
-
- Some configurations of the compiler also support additional special
-options, usually for compatibility with other compilers on the same
-platform.
-
- These options are defined by the macro `TARGET_SWITCHES' in the
-machine description. The default for the options is also defined by
-that macro, which enables you to change the defaults.
-
-* Menu:
-
-* M680x0 Options::
-* M68hc1x Options::
-* VAX Options::
-* SPARC Options::
-* Convex Options::
-* AMD29K Options::
-* ARM Options::
-* MN10200 Options::
-* MN10300 Options::
-* M32R/D Options::
-* M88K Options::
-* RS/6000 and PowerPC Options::
-* RT Options::
-* MIPS Options::
-* i386 and x86-64 Options::
-* HPPA Options::
-* Intel 960 Options::
-* DEC Alpha Options::
-* DEC Alpha/VMS Options::
-* Clipper Options::
-* H8/300 Options::
-* SH Options::
-* System V Options::
-* TMS320C3x/C4x Options::
-* V850 Options::
-* ARC Options::
-* NS32K Options::
-* AVR Options::
-* MCore Options::
-* IA-64 Options::
-* D30V Options::
-* S/390 and zSeries Options::
-* CRIS Options::
-* MMIX Options::
-* PDP-11 Options::
-* Xstormy16 Options::
-* Xtensa Options::
-
-\1f
-File: gcc.info, Node: M680x0 Options, Next: M68hc1x Options, Up: Submodel Options
-
-M680x0 Options
---------------
-
- These are the `-m' options defined for the 68000 series. The default
-values for these options depends on which style of 68000 was selected
-when the compiler was configured; the defaults for the most common
-choices are given below.
-
-`-m68000'
-`-mc68000'
- Generate output for a 68000. This is the default when the
- compiler is configured for 68000-based systems.
-
- Use this option for microcontrollers with a 68000 or EC000 core,
- including the 68008, 68302, 68306, 68307, 68322, 68328 and 68356.
-
-`-m68020'
-`-mc68020'
- Generate output for a 68020. This is the default when the
- compiler is configured for 68020-based systems.
-
-`-m68881'
- Generate output containing 68881 instructions for floating point.
- This is the default for most 68020 systems unless `--nfp' was
- specified when the compiler was configured.
-
-`-m68030'
- Generate output for a 68030. This is the default when the
- compiler is configured for 68030-based systems.
-
-`-m68040'
- Generate output for a 68040. This is the default when the
- compiler is configured for 68040-based systems.
-
- This option inhibits the use of 68881/68882 instructions that have
- to be emulated by software on the 68040. Use this option if your
- 68040 does not have code to emulate those instructions.
-
-`-m68060'
- Generate output for a 68060. This is the default when the
- compiler is configured for 68060-based systems.
-
- This option inhibits the use of 68020 and 68881/68882 instructions
- that have to be emulated by software on the 68060. Use this
- option if your 68060 does not have code to emulate those
- instructions.
-
-`-mcpu32'
- Generate output for a CPU32. This is the default when the
- compiler is configured for CPU32-based systems.
-
- Use this option for microcontrollers with a CPU32 or CPU32+ core,
- including the 68330, 68331, 68332, 68333, 68334, 68336, 68340,
- 68341, 68349 and 68360.
-
-`-m5200'
- Generate output for a 520X "coldfire" family cpu. This is the
- default when the compiler is configured for 520X-based systems.
-
- Use this option for microcontroller with a 5200 core, including
- the MCF5202, MCF5203, MCF5204 and MCF5202.
-
-`-m68020-40'
- Generate output for a 68040, without using any of the new
- instructions. This results in code which can run relatively
- efficiently on either a 68020/68881 or a 68030 or a 68040. The
- generated code does use the 68881 instructions that are emulated
- on the 68040.
-
-`-m68020-60'
- Generate output for a 68060, without using any of the new
- instructions. This results in code which can run relatively
- efficiently on either a 68020/68881 or a 68030 or a 68040. The
- generated code does use the 68881 instructions that are emulated
- on the 68060.
-
-`-mfpa'
- Generate output containing Sun FPA instructions for floating point.
-
-`-msoft-float'
- Generate output containing library calls for floating point.
- *Warning:* the requisite libraries are not available for all m68k
- targets. Normally the facilities of the machine's usual C
- compiler are used, but this can't be done directly in
- cross-compilation. You must make your own arrangements to provide
- suitable library functions for cross-compilation. The embedded
- targets `m68k-*-aout' and `m68k-*-coff' do provide software
- floating point support.
-
-`-mshort'
- Consider type `int' to be 16 bits wide, like `short int'.
-
-`-mnobitfield'
- Do not use the bit-field instructions. The `-m68000', `-mcpu32'
- and `-m5200' options imply `-mnobitfield'.
-
-`-mbitfield'
- Do use the bit-field instructions. The `-m68020' option implies
- `-mbitfield'. This is the default if you use a configuration
- designed for a 68020.
-
-`-mrtd'
- Use a different function-calling convention, in which functions
- that take a fixed number of arguments return with the `rtd'
- instruction, which pops their arguments while returning. This
- saves one instruction in the caller since there is no need to pop
- the arguments there.
-
- This calling convention is incompatible with the one normally used
- on Unix, so you cannot use it if you need to call libraries
- compiled with the Unix compiler.
-
- Also, you must provide function prototypes for all functions that
- take variable numbers of arguments (including `printf'); otherwise
- incorrect code will be generated for calls to those functions.
-
- In addition, seriously incorrect code will result if you call a
- function with too many arguments. (Normally, extra arguments are
- harmlessly ignored.)
-
- The `rtd' instruction is supported by the 68010, 68020, 68030,
- 68040, 68060 and CPU32 processors, but not by the 68000 or 5200.
-
-`-malign-int'
-`-mno-align-int'
- Control whether GCC aligns `int', `long', `long long', `float',
- `double', and `long double' variables on a 32-bit boundary
- (`-malign-int') or a 16-bit boundary (`-mno-align-int'). Aligning
- variables on 32-bit boundaries produces code that runs somewhat
- faster on processors with 32-bit busses at the expense of more
- memory.
-
- *Warning:* if you use the `-malign-int' switch, GCC will align
- structures containing the above types differently than most
- published application binary interface specifications for the m68k.
-
-`-mpcrel'
- Use the pc-relative addressing mode of the 68000 directly, instead
- of using a global offset table. At present, this option implies
- `-fpic', allowing at most a 16-bit offset for pc-relative
- addressing. `-fPIC' is not presently supported with `-mpcrel',
- though this could be supported for 68020 and higher processors.
-
-`-mno-strict-align'
-`-mstrict-align'
- Do not (do) assume that unaligned memory references will be
- handled by the system.
-
-
-\1f
-File: gcc.info, Node: M68hc1x Options, Next: VAX Options, Prev: M680x0 Options, Up: Submodel Options
-
-M68hc1x Options
----------------
-
- These are the `-m' options defined for the 68hc11 and 68hc12
-microcontrollers. The default values for these options depends on
-which style of microcontroller was selected when the compiler was
-configured; the defaults for the most common choices are given below.
-
-`-m6811'
-`-m68hc11'
- Generate output for a 68HC11. This is the default when the
- compiler is configured for 68HC11-based systems.
-
-`-m6812'
-`-m68hc12'
- Generate output for a 68HC12. This is the default when the
- compiler is configured for 68HC12-based systems.
-
-`-mauto-incdec'
- Enable the use of 68HC12 pre and post auto-increment and
- auto-decrement addressing modes.
-
-`-mshort'
- Consider type `int' to be 16 bits wide, like `short int'.
-
-`-msoft-reg-count=COUNT'
- Specify the number of pseudo-soft registers which are used for the
- code generation. The maximum number is 32. Using more pseudo-soft
- register may or may not result in better code depending on the
- program. The default is 4 for 68HC11 and 2 for 68HC12.
-
-
-\1f
-File: gcc.info, Node: VAX Options, Next: SPARC Options, Prev: M68hc1x Options, Up: Submodel Options
-
-VAX Options
------------
-
- These `-m' options are defined for the VAX:
-
-`-munix'
- Do not output certain jump instructions (`aobleq' and so on) that
- the Unix assembler for the VAX cannot handle across long ranges.
-
-`-mgnu'
- Do output those jump instructions, on the assumption that you will
- assemble with the GNU assembler.
-
-`-mg'
- Output code for g-format floating point numbers instead of
- d-format.
-
-\1f
-File: gcc.info, Node: SPARC Options, Next: Convex Options, Prev: VAX Options, Up: Submodel Options
-
-SPARC Options
--------------
-
- These `-m' switches are supported on the SPARC:
-
-`-mno-app-regs'
-`-mapp-regs'
- Specify `-mapp-regs' to generate output using the global registers
- 2 through 4, which the SPARC SVR4 ABI reserves for applications.
- This is the default.
-
- To be fully SVR4 ABI compliant at the cost of some performance
- loss, specify `-mno-app-regs'. You should compile libraries and
- system software with this option.
-
-`-mfpu'
-`-mhard-float'
- Generate output containing floating point instructions. This is
- the default.
-
-`-mno-fpu'
-`-msoft-float'
- Generate output containing library calls for floating point.
- *Warning:* the requisite libraries are not available for all SPARC
- targets. Normally the facilities of the machine's usual C
- compiler are used, but this cannot be done directly in
- cross-compilation. You must make your own arrangements to provide
- suitable library functions for cross-compilation. The embedded
- targets `sparc-*-aout' and `sparclite-*-*' do provide software
- floating point support.
-
- `-msoft-float' changes the calling convention in the output file;
- therefore, it is only useful if you compile _all_ of a program with
- this option. In particular, you need to compile `libgcc.a', the
- library that comes with GCC, with `-msoft-float' in order for this
- to work.
-
-`-mhard-quad-float'
- Generate output containing quad-word (long double) floating point
- instructions.
-
-`-msoft-quad-float'
- Generate output containing library calls for quad-word (long
- double) floating point instructions. The functions called are
- those specified in the SPARC ABI. This is the default.
-
- As of this writing, there are no sparc implementations that have
- hardware support for the quad-word floating point instructions.
- They all invoke a trap handler for one of these instructions, and
- then the trap handler emulates the effect of the instruction.
- Because of the trap handler overhead, this is much slower than
- calling the ABI library routines. Thus the `-msoft-quad-float'
- option is the default.
-
-`-mno-flat'
-`-mflat'
- With `-mflat', the compiler does not generate save/restore
- instructions and will use a "flat" or single register window
- calling convention. This model uses %i7 as the frame pointer and
- is compatible with the normal register window model. Code from
- either may be intermixed. The local registers and the input
- registers (0-5) are still treated as "call saved" registers and
- will be saved on the stack as necessary.
-
- With `-mno-flat' (the default), the compiler emits save/restore
- instructions (except for leaf functions) and is the normal mode of
- operation.
-
-`-mno-unaligned-doubles'
-`-munaligned-doubles'
- Assume that doubles have 8 byte alignment. This is the default.
-
- With `-munaligned-doubles', GCC assumes that doubles have 8 byte
- alignment only if they are contained in another type, or if they
- have an absolute address. Otherwise, it assumes they have 4 byte
- alignment. Specifying this option avoids some rare compatibility
- problems with code generated by other compilers. It is not the
- default because it results in a performance loss, especially for
- floating point code.
-
-`-mno-faster-structs'
-`-mfaster-structs'
- With `-mfaster-structs', the compiler assumes that structures
- should have 8 byte alignment. This enables the use of pairs of
- `ldd' and `std' instructions for copies in structure assignment,
- in place of twice as many `ld' and `st' pairs. However, the use
- of this changed alignment directly violates the Sparc ABI. Thus,
- it's intended only for use on targets where the developer
- acknowledges that their resulting code will not be directly in
- line with the rules of the ABI.
-
-`-mv8'
-`-msparclite'
- These two options select variations on the SPARC architecture.
-
- By default (unless specifically configured for the Fujitsu
- SPARClite), GCC generates code for the v7 variant of the SPARC
- architecture.
-
- `-mv8' will give you SPARC v8 code. The only difference from v7
- code is that the compiler emits the integer multiply and integer
- divide instructions which exist in SPARC v8 but not in SPARC v7.
-
- `-msparclite' will give you SPARClite code. This adds the integer
- multiply, integer divide step and scan (`ffs') instructions which
- exist in SPARClite but not in SPARC v7.
-
- These options are deprecated and will be deleted in a future GCC
- release. They have been replaced with `-mcpu=xxx'.
-
-`-mcypress'
-`-msupersparc'
- These two options select the processor for which the code is
- optimized.
-
- With `-mcypress' (the default), the compiler optimizes code for the
- Cypress CY7C602 chip, as used in the SparcStation/SparcServer 3xx
- series. This is also appropriate for the older SparcStation 1, 2,
- IPX etc.
-
- With `-msupersparc' the compiler optimizes code for the SuperSparc
- cpu, as used in the SparcStation 10, 1000 and 2000 series. This
- flag also enables use of the full SPARC v8 instruction set.
-
- These options are deprecated and will be deleted in a future GCC
- release. They have been replaced with `-mcpu=xxx'.
-
-`-mcpu=CPU_TYPE'
- Set the instruction set, register set, and instruction scheduling
- parameters for machine type CPU_TYPE. Supported values for
- CPU_TYPE are `v7', `cypress', `v8', `supersparc', `sparclite',
- `hypersparc', `sparclite86x', `f930', `f934', `sparclet',
- `tsc701', `v9', and `ultrasparc'.
-
- Default instruction scheduling parameters are used for values that
- select an architecture and not an implementation. These are `v7',
- `v8', `sparclite', `sparclet', `v9'.
-
- Here is a list of each supported architecture and their supported
- implementations.
-
- v7: cypress
- v8: supersparc, hypersparc
- sparclite: f930, f934, sparclite86x
- sparclet: tsc701
- v9: ultrasparc
-
-`-mtune=CPU_TYPE'
- Set the instruction scheduling parameters for machine type
- CPU_TYPE, but do not set the instruction set or register set that
- the option `-mcpu=CPU_TYPE' would.
-
- The same values for `-mcpu=CPU_TYPE' can be used for
- `-mtune=CPU_TYPE', but the only useful values are those that
- select a particular cpu implementation. Those are `cypress',
- `supersparc', `hypersparc', `f930', `f934', `sparclite86x',
- `tsc701', and `ultrasparc'.
-
-
- These `-m' switches are supported in addition to the above on the
-SPARCLET processor.
-
-`-mlittle-endian'
- Generate code for a processor running in little-endian mode.
-
-`-mlive-g0'
- Treat register `%g0' as a normal register. GCC will continue to
- clobber it as necessary but will not assume it always reads as 0.
-
-`-mbroken-saverestore'
- Generate code that does not use non-trivial forms of the `save' and
- `restore' instructions. Early versions of the SPARCLET processor
- do not correctly handle `save' and `restore' instructions used with
- arguments. They correctly handle them used without arguments. A
- `save' instruction used without arguments increments the current
- window pointer but does not allocate a new stack frame. It is
- assumed that the window overflow trap handler will properly handle
- this case as will interrupt handlers.
-
- These `-m' switches are supported in addition to the above on SPARC
-V9 processors in 64-bit environments.
-
-`-mlittle-endian'
- Generate code for a processor running in little-endian mode.
-
-`-m32'
-`-m64'
- Generate code for a 32-bit or 64-bit environment. The 32-bit
- environment sets int, long and pointer to 32 bits. The 64-bit
- environment sets int to 32 bits and long and pointer to 64 bits.
-
-`-mcmodel=medlow'
- Generate code for the Medium/Low code model: the program must be
- linked in the low 32 bits of the address space. Pointers are 64
- bits. Programs can be statically or dynamically linked.
-
-`-mcmodel=medmid'
- Generate code for the Medium/Middle code model: the program must
- be linked in the low 44 bits of the address space, the text
- segment must be less than 2G bytes, and data segment must be
- within 2G of the text segment. Pointers are 64 bits.
-
-`-mcmodel=medany'
- Generate code for the Medium/Anywhere code model: the program may
- be linked anywhere in the address space, the text segment must be
- less than 2G bytes, and data segment must be within 2G of the text
- segment. Pointers are 64 bits.
-
-`-mcmodel=embmedany'
- Generate code for the Medium/Anywhere code model for embedded
- systems: assume a 32-bit text and a 32-bit data segment, both
- starting anywhere (determined at link time). Register %g4 points
- to the base of the data segment. Pointers are still 64 bits.
- Programs are statically linked, PIC is not supported.
-
-`-mstack-bias'
-`-mno-stack-bias'
- With `-mstack-bias', GCC assumes that the stack pointer, and frame
- pointer if present, are offset by -2047 which must be added back
- when making stack frame references. Otherwise, assume no such
- offset is present.
-
-\1f
-File: gcc.info, Node: Convex Options, Next: AMD29K Options, Prev: SPARC Options, Up: Submodel Options
-
-Convex Options
---------------
-
- These `-m' options are defined for Convex:
-
-`-mc1'
- Generate output for C1. The code will run on any Convex machine.
- The preprocessor symbol `__convex__c1__' is defined.
-
-`-mc2'
- Generate output for C2. Uses instructions not available on C1.
- Scheduling and other optimizations are chosen for max performance
- on C2. The preprocessor symbol `__convex_c2__' is defined.
-
-`-mc32'
- Generate output for C32xx. Uses instructions not available on C1.
- Scheduling and other optimizations are chosen for max performance
- on C32. The preprocessor symbol `__convex_c32__' is defined.
-
-`-mc34'
- Generate output for C34xx. Uses instructions not available on C1.
- Scheduling and other optimizations are chosen for max performance
- on C34. The preprocessor symbol `__convex_c34__' is defined.
-
-`-mc38'
- Generate output for C38xx. Uses instructions not available on C1.
- Scheduling and other optimizations are chosen for max performance
- on C38. The preprocessor symbol `__convex_c38__' is defined.
-
-`-margcount'
- Generate code which puts an argument count in the word preceding
- each argument list. This is compatible with regular CC, and a few
- programs may need the argument count word. GDB and other
- source-level debuggers do not need it; this info is in the symbol
- table.
-
-`-mnoargcount'
- Omit the argument count word. This is the default.
-
-`-mvolatile-cache'
- Allow volatile references to be cached. This is the default.
-
-`-mvolatile-nocache'
- Volatile references bypass the data cache, going all the way to
- memory. This is only needed for multi-processor code that does
- not use standard synchronization instructions. Making
- non-volatile references to volatile locations will not necessarily
- work.
-
-`-mlong32'
- Type long is 32 bits, the same as type int. This is the default.
-
-`-mlong64'
- Type long is 64 bits, the same as type long long. This option is
- useless, because no library support exists for it.
-
-\1f
-File: gcc.info, Node: AMD29K Options, Next: ARM Options, Prev: Convex Options, Up: Submodel Options
-
-AMD29K Options
---------------
-
- These `-m' options are defined for the AMD Am29000:
-
-`-mdw'
- Generate code that assumes the `DW' bit is set, i.e., that byte and
- halfword operations are directly supported by the hardware. This
- is the default.
-
-`-mndw'
- Generate code that assumes the `DW' bit is not set.
-
-`-mbw'
- Generate code that assumes the system supports byte and halfword
- write operations. This is the default.
-
-`-mnbw'
- Generate code that assumes the systems does not support byte and
- halfword write operations. `-mnbw' implies `-mndw'.
-
-`-msmall'
- Use a small memory model that assumes that all function addresses
- are either within a single 256 KB segment or at an absolute
- address of less than 256k. This allows the `call' instruction to
- be used instead of a `const', `consth', `calli' sequence.
-
-`-mnormal'
- Use the normal memory model: Generate `call' instructions only when
- calling functions in the same file and `calli' instructions
- otherwise. This works if each file occupies less than 256 KB but
- allows the entire executable to be larger than 256 KB. This is
- the default.
-
-`-mlarge'
- Always use `calli' instructions. Specify this option if you expect
- a single file to compile into more than 256 KB of code.
-
-`-m29050'
- Generate code for the Am29050.
-
-`-m29000'
- Generate code for the Am29000. This is the default.
-
-`-mkernel-registers'
- Generate references to registers `gr64-gr95' instead of to
- registers `gr96-gr127'. This option can be used when compiling
- kernel code that wants a set of global registers disjoint from
- that used by user-mode code.
-
- Note that when this option is used, register names in `-f' flags
- must use the normal, user-mode, names.
-
-`-muser-registers'
- Use the normal set of global registers, `gr96-gr127'. This is the
- default.
-
-`-mstack-check'
-`-mno-stack-check'
- Insert (or do not insert) a call to `__msp_check' after each stack
- adjustment. This is often used for kernel code.
-
-`-mstorem-bug'
-`-mno-storem-bug'
- `-mstorem-bug' handles 29k processors which cannot handle the
- separation of a mtsrim insn and a storem instruction (most 29000
- chips to date, but not the 29050).
-
-`-mno-reuse-arg-regs'
-`-mreuse-arg-regs'
- `-mno-reuse-arg-regs' tells the compiler to only use incoming
- argument registers for copying out arguments. This helps detect
- calling a function with fewer arguments than it was declared with.
-
-`-mno-impure-text'
-`-mimpure-text'
- `-mimpure-text', used in addition to `-shared', tells the compiler
- to not pass `-assert pure-text' to the linker when linking a
- shared object.
-
-`-msoft-float'
- Generate output containing library calls for floating point.
- *Warning:* the requisite libraries are not part of GCC. Normally
- the facilities of the machine's usual C compiler are used, but
- this can't be done directly in cross-compilation. You must make
- your own arrangements to provide suitable library functions for
- cross-compilation.
-
-`-mno-multm'
- Do not generate multm or multmu instructions. This is useful for
- some embedded systems which do not have trap handlers for these
- instructions.
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: ARM Options, Next: MN10200 Options, Prev: AMD29K Options, Up: Submodel Options
-
-ARM Options
------------
-
- These `-m' options are defined for Advanced RISC Machines (ARM)
-architectures:
-
-`-mapcs-frame'
- Generate a stack frame that is compliant with the ARM Procedure
- Call Standard for all functions, even if this is not strictly
- necessary for correct execution of the code. Specifying
- `-fomit-frame-pointer' with this option will cause the stack
- frames not to be generated for leaf functions. The default is
- `-mno-apcs-frame'.
-
-`-mapcs'
- This is a synonym for `-mapcs-frame'.
-
-`-mapcs-26'
- Generate code for a processor running with a 26-bit program
- counter, and conforming to the function calling standards for the
- APCS 26-bit option. This option replaces the `-m2' and `-m3'
- options of previous releases of the compiler.
-
-`-mapcs-32'
- Generate code for a processor running with a 32-bit program
- counter, and conforming to the function calling standards for the
- APCS 32-bit option. This option replaces the `-m6' option of
- previous releases of the compiler.
-
-`-mthumb-interwork'
- Generate code which supports calling between the ARM and Thumb
- instruction sets. Without this option the two instruction sets
- cannot be reliably used inside one program. The default is
- `-mno-thumb-interwork', since slightly larger code is generated
- when `-mthumb-interwork' is specified.
-
-`-mno-sched-prolog'
- Prevent the reordering of instructions in the function prolog, or
- the merging of those instruction with the instructions in the
- function's body. This means that all functions will start with a
- recognizable set of instructions (or in fact one of a choice from
- a small set of different function prologues), and this information
- can be used to locate the start if functions inside an executable
- piece of code. The default is `-msched-prolog'.
-
-`-mhard-float'
- Generate output containing floating point instructions. This is
- the default.
-
-`-msoft-float'
- Generate output containing library calls for floating point.
- *Warning:* the requisite libraries are not available for all ARM
- targets. Normally the facilities of the machine's usual C
- compiler are used, but this cannot be done directly in
- cross-compilation. You must make your own arrangements to provide
- suitable library functions for cross-compilation.
-
- `-msoft-float' changes the calling convention in the output file;
- therefore, it is only useful if you compile _all_ of a program with
- this option. In particular, you need to compile `libgcc.a', the
- library that comes with GCC, with `-msoft-float' in order for this
- to work.
-
-`-mlittle-endian'
- Generate code for a processor running in little-endian mode. This
- is the default for all standard configurations.
-
-`-mbig-endian'
- Generate code for a processor running in big-endian mode; the
- default is to compile code for a little-endian processor.
-
-`-mwords-little-endian'
- This option only applies when generating code for big-endian
- processors. Generate code for a little-endian word order but a
- big-endian byte order. That is, a byte order of the form
- `32107654'. Note: this option should only be used if you require
- compatibility with code for big-endian ARM processors generated by
- versions of the compiler prior to 2.8.
-
-`-malignment-traps'
- Generate code that will not trap if the MMU has alignment traps
- enabled. On ARM architectures prior to ARMv4, there were no
- instructions to access half-word objects stored in memory.
- However, when reading from memory a feature of the ARM
- architecture allows a word load to be used, even if the address is
- unaligned, and the processor core will rotate the data as it is
- being loaded. This option tells the compiler that such misaligned
- accesses will cause a MMU trap and that it should instead
- synthesise the access as a series of byte accesses. The compiler
- can still use word accesses to load half-word data if it knows
- that the address is aligned to a word boundary.
-
- This option is ignored when compiling for ARM architecture 4 or
- later, since these processors have instructions to directly access
- half-word objects in memory.
-
-`-mno-alignment-traps'
- Generate code that assumes that the MMU will not trap unaligned
- accesses. This produces better code when the target instruction
- set does not have half-word memory operations (i.e.
- implementations prior to ARMv4).
-
- Note that you cannot use this option to access unaligned word
- objects, since the processor will only fetch one 32-bit aligned
- object from memory.
-
- The default setting for most targets is `-mno-alignment-traps',
- since this produces better code when there are no half-word memory
- instructions available.
-
-`-mshort-load-bytes'
-`-mno-short-load-words'
- These are deprecated aliases for `-malignment-traps'.
-
-`-mno-short-load-bytes'
-`-mshort-load-words'
- This are deprecated aliases for `-mno-alignment-traps'.
-
-`-mbsd'
- This option only applies to RISC iX. Emulate the native BSD-mode
- compiler. This is the default if `-ansi' is not specified.
-
-`-mxopen'
- This option only applies to RISC iX. Emulate the native
- X/Open-mode compiler.
-
-`-mno-symrename'
- This option only applies to RISC iX. Do not run the assembler
- post-processor, `symrename', after code has been assembled.
- Normally it is necessary to modify some of the standard symbols in
- preparation for linking with the RISC iX C library; this option
- suppresses this pass. The post-processor is never run when the
- compiler is built for cross-compilation.
-
-`-mcpu=NAME'
- This specifies the name of the target ARM processor. GCC uses
- this name to determine what kind of instructions it can emit when
- generating assembly code. Permissible names are: `arm2', `arm250',
- `arm3', `arm6', `arm60', `arm600', `arm610', `arm620', `arm7',
- `arm7m', `arm7d', `arm7dm', `arm7di', `arm7dmi', `arm70', `arm700',
- `arm700i', `arm710', `arm710c', `arm7100', `arm7500', `arm7500fe',
- `arm7tdmi', `arm8', `strongarm', `strongarm110', `strongarm1100',
- `arm8', `arm810', `arm9', `arm9e', `arm920', `arm920t', `arm940t',
- `arm9tdmi', `arm10tdmi', `arm1020t', `xscale'.
-
-`-mtune=NAME'
- This option is very similar to the `-mcpu=' option, except that
- instead of specifying the actual target processor type, and hence
- restricting which instructions can be used, it specifies that GCC
- should tune the performance of the code as if the target were of
- the type specified in this option, but still choosing the
- instructions that it will generate based on the cpu specified by a
- `-mcpu=' option. For some ARM implementations better performance
- can be obtained by using this option.
-
-`-march=NAME'
- This specifies the name of the target ARM architecture. GCC uses
- this name to determine what kind of instructions it can emit when
- generating assembly code. This option can be used in conjunction
- with or instead of the `-mcpu=' option. Permissible names are:
- `armv2', `armv2a', `armv3', `armv3m', `armv4', `armv4t', `armv5',
- `armv5t', `armv5te'.
-
-`-mfpe=NUMBER'
-`-mfp=NUMBER'
- This specifies the version of the floating point emulation
- available on the target. Permissible values are 2 and 3. `-mfp='
- is a synonym for `-mfpe=', for compatibility with older versions
- of GCC.
-
-`-mstructure-size-boundary=N'
- The size of all structures and unions will be rounded up to a
- multiple of the number of bits set by this option. Permissible
- values are 8 and 32. The default value varies for different
- toolchains. For the COFF targeted toolchain the default value is
- 8. Specifying the larger number can produce faster, more
- efficient code, but can also increase the size of the program.
- The two values are potentially incompatible. Code compiled with
- one value cannot necessarily expect to work with code or libraries
- compiled with the other value, if they exchange information using
- structures or unions.
-
-`-mabort-on-noreturn'
- Generate a call to the function `abort' at the end of a `noreturn'
- function. It will be executed if the function tries to return.
-
-`-mlong-calls'
-`-mno-long-calls'
- Tells the compiler to perform function calls by first loading the
- address of the function into a register and then performing a
- subroutine call on this register. This switch is needed if the
- target function will lie outside of the 64 megabyte addressing
- range of the offset based version of subroutine call instruction.
-
- Even if this switch is enabled, not all function calls will be
- turned into long calls. The heuristic is that static functions,
- functions which have the `short-call' attribute, functions that
- are inside the scope of a `#pragma no_long_calls' directive and
- functions whose definitions have already been compiled within the
- current compilation unit, will not be turned into long calls. The
- exception to this rule is that weak function definitions,
- functions with the `long-call' attribute or the `section'
- attribute, and functions that are within the scope of a `#pragma
- long_calls' directive, will always be turned into long calls.
-
- This feature is not enabled by default. Specifying
- `-mno-long-calls' will restore the default behavior, as will
- placing the function calls within the scope of a `#pragma
- long_calls_off' directive. Note these switches have no effect on
- how the compiler generates code to handle function calls via
- function pointers.
-
-`-mnop-fun-dllimport'
- Disable support for the `dllimport' attribute.
-
-`-msingle-pic-base'
- Treat the register used for PIC addressing as read-only, rather
- than loading it in the prologue for each function. The run-time
- system is responsible for initializing this register with an
- appropriate value before execution begins.
-
-`-mpic-register=REG'
- Specify the register to be used for PIC addressing. The default
- is R10 unless stack-checking is enabled, when R9 is used.
-
-`-mpoke-function-name'
- Write the name of each function into the text section, directly
- preceding the function prologue. The generated code is similar to
- this:
-
- t0
- .ascii "arm_poke_function_name", 0
- .align
- t1
- .word 0xff000000 + (t1 - t0)
- arm_poke_function_name
- mov ip, sp
- stmfd sp!, {fp, ip, lr, pc}
- sub fp, ip, #4
-
- When performing a stack backtrace, code can inspect the value of
- `pc' stored at `fp + 0'. If the trace function then looks at
- location `pc - 12' and the top 8 bits are set, then we know that
- there is a function name embedded immediately preceding this
- location and has length `((pc[-3]) & 0xff000000)'.
-
-`-mthumb'
- Generate code for the 16-bit Thumb instruction set. The default
- is to use the 32-bit ARM instruction set.
-
-`-mtpcs-frame'
- Generate a stack frame that is compliant with the Thumb Procedure
- Call Standard for all non-leaf functions. (A leaf function is one
- that does not call any other functions.) The default is
- `-mno-tpcs-frame'.
-
-`-mtpcs-leaf-frame'
- Generate a stack frame that is compliant with the Thumb Procedure
- Call Standard for all leaf functions. (A leaf function is one
- that does not call any other functions.) The default is
- `-mno-apcs-leaf-frame'.
-
-`-mcallee-super-interworking'
- Gives all externally visible functions in the file being compiled
- an ARM instruction set header which switches to Thumb mode before
- executing the rest of the function. This allows these functions
- to be called from non-interworking code.
-
-`-mcaller-super-interworking'
- Allows calls via function pointers (including virtual functions) to
- execute correctly regardless of whether the target code has been
- compiled for interworking or not. There is a small overhead in
- the cost of executing a function pointer if this option is enabled.
-
-
-\1f
-File: gcc.info, Node: MN10200 Options, Next: MN10300 Options, Prev: ARM Options, Up: Submodel Options
-
-MN10200 Options
----------------
-
- These `-m' options are defined for Matsushita MN10200 architectures:
-`-mrelax'
- Indicate to the linker that it should perform a relaxation
- optimization pass to shorten branches, calls and absolute memory
- addresses. This option only has an effect when used on the
- command line for the final link step.
-
- This option makes symbolic debugging impossible.
-
-\1f
-File: gcc.info, Node: MN10300 Options, Next: M32R/D Options, Prev: MN10200 Options, Up: Submodel Options
-
-MN10300 Options
----------------
-
- These `-m' options are defined for Matsushita MN10300 architectures:
-
-`-mmult-bug'
- Generate code to avoid bugs in the multiply instructions for the
- MN10300 processors. This is the default.
-
-`-mno-mult-bug'
- Do not generate code to avoid bugs in the multiply instructions
- for the MN10300 processors.
-
-`-mam33'
- Generate code which uses features specific to the AM33 processor.
-
-`-mno-am33'
- Do not generate code which uses features specific to the AM33
- processor. This is the default.
-
-`-mno-crt0'
- Do not link in the C run-time initialization object file.
-
-`-mrelax'
- Indicate to the linker that it should perform a relaxation
- optimization pass to shorten branches, calls and absolute memory
- addresses. This option only has an effect when used on the
- command line for the final link step.
-
- This option makes symbolic debugging impossible.
-
-\1f
-File: gcc.info, Node: M32R/D Options, Next: M88K Options, Prev: MN10300 Options, Up: Submodel Options
-
-M32R/D Options
---------------
-
- These `-m' options are defined for Mitsubishi M32R/D architectures:
-
-`-m32rx'
- Generate code for the M32R/X.
-
-`-m32r'
- Generate code for the M32R. This is the default.
-
-`-mcode-model=small'
- Assume all objects live in the lower 16MB of memory (so that their
- addresses can be loaded with the `ld24' instruction), and assume
- all subroutines are reachable with the `bl' instruction. This is
- the default.
-
- The addressability of a particular object can be set with the
- `model' attribute.
-
-`-mcode-model=medium'
- Assume objects may be anywhere in the 32-bit address space (the
- compiler will generate `seth/add3' instructions to load their
- addresses), and assume all subroutines are reachable with the `bl'
- instruction.
-
-`-mcode-model=large'
- Assume objects may be anywhere in the 32-bit address space (the
- compiler will generate `seth/add3' instructions to load their
- addresses), and assume subroutines may not be reachable with the
- `bl' instruction (the compiler will generate the much slower
- `seth/add3/jl' instruction sequence).
-
-`-msdata=none'
- Disable use of the small data area. Variables will be put into
- one of `.data', `bss', or `.rodata' (unless the `section'
- attribute has been specified). This is the default.
-
- The small data area consists of sections `.sdata' and `.sbss'.
- Objects may be explicitly put in the small data area with the
- `section' attribute using one of these sections.
-
-`-msdata=sdata'
- Put small global and static data in the small data area, but do not
- generate special code to reference them.
-
-`-msdata=use'
- Put small global and static data in the small data area, and
- generate special instructions to reference them.
-
-`-G NUM'
- Put global and static objects less than or equal to NUM bytes into
- the small data or bss sections instead of the normal data or bss
- sections. The default value of NUM is 8. The `-msdata' option
- must be set to one of `sdata' or `use' for this option to have any
- effect.
-
- All modules should be compiled with the same `-G NUM' value.
- Compiling with different values of NUM may or may not work; if it
- doesn't the linker will give an error message--incorrect code will
- not be generated.
-
-
-\1f
-File: gcc.info, Node: M88K Options, Next: RS/6000 and PowerPC Options, Prev: M32R/D Options, Up: Submodel Options
-
-M88K Options
-------------
-
- These `-m' options are defined for Motorola 88k architectures:
-
-`-m88000'
- Generate code that works well on both the m88100 and the m88110.
-
-`-m88100'
- Generate code that works best for the m88100, but that also runs
- on the m88110.
-
-`-m88110'
- Generate code that works best for the m88110, and may not run on
- the m88100.
-
-`-mbig-pic'
- Obsolete option to be removed from the next revision. Use `-fPIC'.
-
-`-midentify-revision'
- Include an `ident' directive in the assembler output recording the
- source file name, compiler name and version, timestamp, and
- compilation flags used.
-
-`-mno-underscores'
- In assembler output, emit symbol names without adding an underscore
- character at the beginning of each name. The default is to use an
- underscore as prefix on each name.
-
-`-mocs-debug-info'
-`-mno-ocs-debug-info'
- Include (or omit) additional debugging information (about
- registers used in each stack frame) as specified in the 88open
- Object Compatibility Standard, "OCS". This extra information
- allows debugging of code that has had the frame pointer
- eliminated. The default for DG/UX, SVr4, and Delta 88 SVr3.2 is
- to include this information; other 88k configurations omit this
- information by default.
-
-`-mocs-frame-position'
- When emitting COFF debugging information for automatic variables
- and parameters stored on the stack, use the offset from the
- canonical frame address, which is the stack pointer (register 31)
- on entry to the function. The DG/UX, SVr4, Delta88 SVr3.2, and
- BCS configurations use `-mocs-frame-position'; other 88k
- configurations have the default `-mno-ocs-frame-position'.
-
-`-mno-ocs-frame-position'
- When emitting COFF debugging information for automatic variables
- and parameters stored on the stack, use the offset from the frame
- pointer register (register 30). When this option is in effect,
- the frame pointer is not eliminated when debugging information is
- selected by the -g switch.
-
-`-moptimize-arg-area'
- Save space by reorganizing the stack frame. This option generates
- code that does not agree with the 88open specifications, but uses
- less memory.
-
-`-mno-optimize-arg-area'
- Do not reorganize the stack frame to save space. This is the
- default. The generated conforms to the specification, but uses
- more memory.
-
-`-mshort-data-NUM'
- Generate smaller data references by making them relative to `r0',
- which allows loading a value using a single instruction (rather
- than the usual two). You control which data references are
- affected by specifying NUM with this option. For example, if you
- specify `-mshort-data-512', then the data references affected are
- those involving displacements of less than 512 bytes.
- `-mshort-data-NUM' is not effective for NUM greater than 64k.
-
-`-mserialize-volatile'
-`-mno-serialize-volatile'
- Do, or don't, generate code to guarantee sequential consistency of
- volatile memory references. By default, consistency is guaranteed.
-
- The order of memory references made by the MC88110 processor does
- not always match the order of the instructions requesting those
- references. In particular, a load instruction may execute before
- a preceding store instruction. Such reordering violates
- sequential consistency of volatile memory references, when there
- are multiple processors. When consistency must be guaranteed,
- GCC generates special instructions, as needed, to force execution
- in the proper order.
-
- The MC88100 processor does not reorder memory references and so
- always provides sequential consistency. However, by default, GCC
- generates the special instructions to guarantee consistency even
- when you use `-m88100', so that the code may be run on an MC88110
- processor. If you intend to run your code only on the MC88100
- processor, you may use `-mno-serialize-volatile'.
-
- The extra code generated to guarantee consistency may affect the
- performance of your application. If you know that you can safely
- forgo this guarantee, you may use `-mno-serialize-volatile'.
-
-`-msvr4'
-`-msvr3'
- Turn on (`-msvr4') or off (`-msvr3') compiler extensions related
- to System V release 4 (SVr4). This controls the following:
-
- 1. Which variant of the assembler syntax to emit.
-
- 2. `-msvr4' makes the C preprocessor recognize `#pragma weak'
- that is used on System V release 4.
-
- 3. `-msvr4' makes GCC issue additional declaration directives
- used in SVr4.
-
- `-msvr4' is the default for the m88k-motorola-sysv4 and
- m88k-dg-dgux m88k configurations. `-msvr3' is the default for all
- other m88k configurations.
-
-`-mversion-03.00'
- This option is obsolete, and is ignored.
-
-`-mno-check-zero-division'
-`-mcheck-zero-division'
- Do, or don't, generate code to guarantee that integer division by
- zero will be detected. By default, detection is guaranteed.
-
- Some models of the MC88100 processor fail to trap upon integer
- division by zero under certain conditions. By default, when
- compiling code that might be run on such a processor, GCC
- generates code that explicitly checks for zero-valued divisors and
- traps with exception number 503 when one is detected. Use of
- `-mno-check-zero-division' suppresses such checking for code
- generated to run on an MC88100 processor.
-
- GCC assumes that the MC88110 processor correctly detects all
- instances of integer division by zero. When `-m88110' is
- specified, no explicit checks for zero-valued divisors are
- generated, and both `-mcheck-zero-division' and
- `-mno-check-zero-division' are ignored.
-
-`-muse-div-instruction'
- Use the div instruction for signed integer division on the MC88100
- processor. By default, the div instruction is not used.
-
- On the MC88100 processor the signed integer division instruction
- div) traps to the operating system on a negative operand. The
- operating system transparently completes the operation, but at a
- large cost in execution time. By default, when compiling code
- that might be run on an MC88100 processor, GCC emulates signed
- integer division using the unsigned integer division instruction
- divu), thereby avoiding the large penalty of a trap to the
- operating system. Such emulation has its own, smaller, execution
- cost in both time and space. To the extent that your code's
- important signed integer division operations are performed on two
- nonnegative operands, it may be desirable to use the div
- instruction directly.
-
- On the MC88110 processor the div instruction (also known as the
- divs instruction) processes negative operands without trapping to
- the operating system. When `-m88110' is specified,
- `-muse-div-instruction' is ignored, and the div instruction is used
- for signed integer division.
-
- Note that the result of dividing `INT_MIN' by -1 is undefined. In
- particular, the behavior of such a division with and without
- `-muse-div-instruction' may differ.
-
-`-mtrap-large-shift'
-`-mhandle-large-shift'
- Include code to detect bit-shifts of more than 31 bits;
- respectively, trap such shifts or emit code to handle them
- properly. By default GCC makes no special provision for large bit
- shifts.
-
-`-mwarn-passed-structs'
- Warn when a function passes a struct as an argument or result.
- Structure-passing conventions have changed during the evolution of
- the C language, and are often the source of portability problems.
- By default, GCC issues no such warning.
-
-\1f
-File: gcc.info, Node: RS/6000 and PowerPC Options, Next: RT Options, Prev: M88K Options, Up: Submodel Options
-
-IBM RS/6000 and PowerPC Options
--------------------------------
-
- These `-m' options are defined for the IBM RS/6000 and PowerPC:
-`-mpower'
-`-mno-power'
-`-mpower2'
-`-mno-power2'
-`-mpowerpc'
-`-mno-powerpc'
-`-mpowerpc-gpopt'
-`-mno-powerpc-gpopt'
-`-mpowerpc-gfxopt'
-`-mno-powerpc-gfxopt'
-`-mpowerpc64'
-`-mno-powerpc64'
- GCC supports two related instruction set architectures for the
- RS/6000 and PowerPC. The "POWER" instruction set are those
- instructions supported by the `rios' chip set used in the original
- RS/6000 systems and the "PowerPC" instruction set is the
- architecture of the Motorola MPC5xx, MPC6xx, MPC8xx
- microprocessors, and the IBM 4xx microprocessors.
-
- Neither architecture is a subset of the other. However there is a
- large common subset of instructions supported by both. An MQ
- register is included in processors supporting the POWER
- architecture.
-
- You use these options to specify which instructions are available
- on the processor you are using. The default value of these
- options is determined when configuring GCC. Specifying the
- `-mcpu=CPU_TYPE' overrides the specification of these options. We
- recommend you use the `-mcpu=CPU_TYPE' option rather than the
- options listed above.
-
- The `-mpower' option allows GCC to generate instructions that are
- found only in the POWER architecture and to use the MQ register.
- Specifying `-mpower2' implies `-power' and also allows GCC to
- generate instructions that are present in the POWER2 architecture
- but not the original POWER architecture.
-
- The `-mpowerpc' option allows GCC to generate instructions that
- are found only in the 32-bit subset of the PowerPC architecture.
- Specifying `-mpowerpc-gpopt' implies `-mpowerpc' and also allows
- GCC to use the optional PowerPC architecture instructions in the
- General Purpose group, including floating-point square root.
- Specifying `-mpowerpc-gfxopt' implies `-mpowerpc' and also allows
- GCC to use the optional PowerPC architecture instructions in the
- Graphics group, including floating-point select.
-
- The `-mpowerpc64' option allows GCC to generate the additional
- 64-bit instructions that are found in the full PowerPC64
- architecture and to treat GPRs as 64-bit, doubleword quantities.
- GCC defaults to `-mno-powerpc64'.
-
- If you specify both `-mno-power' and `-mno-powerpc', GCC will use
- only the instructions in the common subset of both architectures
- plus some special AIX common-mode calls, and will not use the MQ
- register. Specifying both `-mpower' and `-mpowerpc' permits GCC
- to use any instruction from either architecture and to allow use
- of the MQ register; specify this for the Motorola MPC601.
-
-`-mnew-mnemonics'
-`-mold-mnemonics'
- Select which mnemonics to use in the generated assembler code.
- With `-mnew-mnemonics', GCC uses the assembler mnemonics defined
- for the PowerPC architecture. With `-mold-mnemonics' it uses the
- assembler mnemonics defined for the POWER architecture.
- Instructions defined in only one architecture have only one
- mnemonic; GCC uses that mnemonic irrespective of which of these
- options is specified.
-
- GCC defaults to the mnemonics appropriate for the architecture in
- use. Specifying `-mcpu=CPU_TYPE' sometimes overrides the value of
- these option. Unless you are building a cross-compiler, you
- should normally not specify either `-mnew-mnemonics' or
- `-mold-mnemonics', but should instead accept the default.
-
-`-mcpu=CPU_TYPE'
- Set architecture type, register usage, choice of mnemonics, and
- instruction scheduling parameters for machine type CPU_TYPE.
- Supported values for CPU_TYPE are `rios', `rios1', `rsc', `rios2',
- `rs64a', `601', `602', `603', `603e', `604', `604e', `620', `630',
- `740', `7400', `7450', `750', `power', `power2', `powerpc', `403',
- `505', `801', `821', `823', and `860' and `common'.
-
- `-mcpu=common' selects a completely generic processor. Code
- generated under this option will run on any POWER or PowerPC
- processor. GCC will use only the instructions in the common
- subset of both architectures, and will not use the MQ register.
- GCC assumes a generic processor model for scheduling purposes.
-
- `-mcpu=power', `-mcpu=power2', `-mcpu=powerpc', and
- `-mcpu=powerpc64' specify generic POWER, POWER2, pure 32-bit
- PowerPC (i.e., not MPC601), and 64-bit PowerPC architecture machine
- types, with an appropriate, generic processor model assumed for
- scheduling purposes.
-
- The other options specify a specific processor. Code generated
- under those options will run best on that processor, and may not
- run at all on others.
-
- The `-mcpu' options automatically enable or disable other `-m'
- options as follows:
-
- `common'
- `-mno-power', `-mno-powerc'
-
- `power'
- `power2'
- `rios1'
- `rios2'
- `rsc'
- `-mpower', `-mno-powerpc', `-mno-new-mnemonics'
-
- `powerpc'
- `rs64a'
- `602'
- `603'
- `603e'
- `604'
- `620'
- `630'
- `740'
- `7400'
- `7450'
- `750'
- `505'
- `-mno-power', `-mpowerpc', `-mnew-mnemonics'
-
- `601'
- `-mpower', `-mpowerpc', `-mnew-mnemonics'
-
- `403'
- `821'
- `860'
- `-mno-power', `-mpowerpc', `-mnew-mnemonics', `-msoft-float'
-
-`-mtune=CPU_TYPE'
- Set the instruction scheduling parameters for machine type
- CPU_TYPE, but do not set the architecture type, register usage, or
- choice of mnemonics, as `-mcpu=CPU_TYPE' would. The same values
- for CPU_TYPE are used for `-mtune' as for `-mcpu'. If both are
- specified, the code generated will use the architecture,
- registers, and mnemonics set by `-mcpu', but the scheduling
- parameters set by `-mtune'.
-
-`-maltivec'
-`-mno-altivec'
- These switches enable or disable the use of built-in functions that
- allow access to the AltiVec instruction set. You may also need to
- set `-mabi=altivec' to adjust the current ABI with AltiVec ABI
- enhancements.
-
-`-mfull-toc'
-`-mno-fp-in-toc'
-`-mno-sum-in-toc'
-`-mminimal-toc'
- Modify generation of the TOC (Table Of Contents), which is created
- for every executable file. The `-mfull-toc' option is selected by
- default. In that case, GCC will allocate at least one TOC entry
- for each unique non-automatic variable reference in your program.
- GCC will also place floating-point constants in the TOC. However,
- only 16,384 entries are available in the TOC.
-
- If you receive a linker error message that saying you have
- overflowed the available TOC space, you can reduce the amount of
- TOC space used with the `-mno-fp-in-toc' and `-mno-sum-in-toc'
- options. `-mno-fp-in-toc' prevents GCC from putting floating-point
- constants in the TOC and `-mno-sum-in-toc' forces GCC to generate
- code to calculate the sum of an address and a constant at run-time
- instead of putting that sum into the TOC. You may specify one or
- both of these options. Each causes GCC to produce very slightly
- slower and larger code at the expense of conserving TOC space.
-
- If you still run out of space in the TOC even when you specify
- both of these options, specify `-mminimal-toc' instead. This
- option causes GCC to make only one TOC entry for every file. When
- you specify this option, GCC will produce code that is slower and
- larger but which uses extremely little TOC space. You may wish to
- use this option only on files that contain less frequently
- executed code.
-
-`-maix64'
-`-maix32'
- Enable 64-bit AIX ABI and calling convention: 64-bit pointers,
- 64-bit `long' type, and the infrastructure needed to support them.
- Specifying `-maix64' implies `-mpowerpc64' and `-mpowerpc', while
- `-maix32' disables the 64-bit ABI and implies `-mno-powerpc64'.
- GCC defaults to `-maix32'.
-
-`-mxl-call'
-`-mno-xl-call'
- On AIX, pass floating-point arguments to prototyped functions
- beyond the register save area (RSA) on the stack in addition to
- argument FPRs. The AIX calling convention was extended but not
- initially documented to handle an obscure K&R C case of calling a
- function that takes the address of its arguments with fewer
- arguments than declared. AIX XL compilers access floating point
- arguments which do not fit in the RSA from the stack when a
- subroutine is compiled without optimization. Because always
- storing floating-point arguments on the stack is inefficient and
- rarely needed, this option is not enabled by default and only is
- necessary when calling subroutines compiled by AIX XL compilers
- without optimization.
-
-`-mpe'
- Support "IBM RS/6000 SP" "Parallel Environment" (PE). Link an
- application written to use message passing with special startup
- code to enable the application to run. The system must have PE
- installed in the standard location (`/usr/lpp/ppe.poe/'), or the
- `specs' file must be overridden with the `-specs=' option to
- specify the appropriate directory location. The Parallel
- Environment does not support threads, so the `-mpe' option and the
- `-pthread' option are incompatible.
-
-`-msoft-float'
-`-mhard-float'
- Generate code that does not use (uses) the floating-point register
- set. Software floating point emulation is provided if you use the
- `-msoft-float' option, and pass the option to GCC when linking.
-
-`-mmultiple'
-`-mno-multiple'
- Generate code that uses (does not use) the load multiple word
- instructions and the store multiple word instructions. These
- instructions are generated by default on POWER systems, and not
- generated on PowerPC systems. Do not use `-mmultiple' on little
- endian PowerPC systems, since those instructions do not work when
- the processor is in little endian mode. The exceptions are PPC740
- and PPC750 which permit the instructions usage in little endian
- mode.
-
-`-mstring'
-`-mno-string'
- Generate code that uses (does not use) the load string instructions
- and the store string word instructions to save multiple registers
- and do small block moves. These instructions are generated by
- default on POWER systems, and not generated on PowerPC systems.
- Do not use `-mstring' on little endian PowerPC systems, since those
- instructions do not work when the processor is in little endian
- mode. The exceptions are PPC740 and PPC750 which permit the
- instructions usage in little endian mode.
-
-`-mupdate'
-`-mno-update'
- Generate code that uses (does not use) the load or store
- instructions that update the base register to the address of the
- calculated memory location. These instructions are generated by
- default. If you use `-mno-update', there is a small window
- between the time that the stack pointer is updated and the address
- of the previous frame is stored, which means code that walks the
- stack frame across interrupts or signals may get corrupted data.
-
-`-mfused-madd'
-`-mno-fused-madd'
- Generate code that uses (does not use) the floating point multiply
- and accumulate instructions. These instructions are generated by
- default if hardware floating is used.
-
-`-mno-bit-align'
-`-mbit-align'
- On System V.4 and embedded PowerPC systems do not (do) force
- structures and unions that contain bit-fields to be aligned to the
- base type of the bit-field.
-
- For example, by default a structure containing nothing but 8
- `unsigned' bit-fields of length 1 would be aligned to a 4 byte
- boundary and have a size of 4 bytes. By using `-mno-bit-align',
- the structure would be aligned to a 1 byte boundary and be one
- byte in size.
-
-`-mno-strict-align'
-`-mstrict-align'
- On System V.4 and embedded PowerPC systems do not (do) assume that
- unaligned memory references will be handled by the system.
-
-`-mrelocatable'
-`-mno-relocatable'
- On embedded PowerPC systems generate code that allows (does not
- allow) the program to be relocated to a different address at
- runtime. If you use `-mrelocatable' on any module, all objects
- linked together must be compiled with `-mrelocatable' or
- `-mrelocatable-lib'.
-
-`-mrelocatable-lib'
-`-mno-relocatable-lib'
- On embedded PowerPC systems generate code that allows (does not
- allow) the program to be relocated to a different address at
- runtime. Modules compiled with `-mrelocatable-lib' can be linked
- with either modules compiled without `-mrelocatable' and
- `-mrelocatable-lib' or with modules compiled with the
- `-mrelocatable' options.
-
-`-mno-toc'
-`-mtoc'
- On System V.4 and embedded PowerPC systems do not (do) assume that
- register 2 contains a pointer to a global area pointing to the
- addresses used in the program.
-
-`-mlittle'
-`-mlittle-endian'
- On System V.4 and embedded PowerPC systems compile code for the
- processor in little endian mode. The `-mlittle-endian' option is
- the same as `-mlittle'.
-
-`-mbig'
-`-mbig-endian'
- On System V.4 and embedded PowerPC systems compile code for the
- processor in big endian mode. The `-mbig-endian' option is the
- same as `-mbig'.
-
-`-mcall-sysv'
- On System V.4 and embedded PowerPC systems compile code using
- calling conventions that adheres to the March 1995 draft of the
- System V Application Binary Interface, PowerPC processor
- supplement. This is the default unless you configured GCC using
- `powerpc-*-eabiaix'.
-
-`-mcall-sysv-eabi'
- Specify both `-mcall-sysv' and `-meabi' options.
-
-`-mcall-sysv-noeabi'
- Specify both `-mcall-sysv' and `-mno-eabi' options.
-
-`-mcall-aix'
- On System V.4 and embedded PowerPC systems compile code using
- calling conventions that are similar to those used on AIX. This
- is the default if you configured GCC using `powerpc-*-eabiaix'.
-
-`-mcall-solaris'
- On System V.4 and embedded PowerPC systems compile code for the
- Solaris operating system.
-
-`-mcall-linux'
- On System V.4 and embedded PowerPC systems compile code for the
- Linux-based GNU system.
-
-`-mcall-gnu'
- On System V.4 and embedded PowerPC systems compile code for the
- Hurd-based GNU system.
-
-`-mcall-netbsd'
- On System V.4 and embedded PowerPC systems compile code for the
- NetBSD operating system.
-
-`-maix-struct-return'
- Return all structures in memory (as specified by the AIX ABI).
-
-`-msvr4-struct-return'
- Return structures smaller than 8 bytes in registers (as specified
- by the SVR4 ABI).
-
-`-mabi=altivec'
- Extend the current ABI with AltiVec ABI extensions. This does not
- change the default ABI, instead it adds the AltiVec ABI extensions
- to the current ABI.
-
-`-mabi=no-altivec'
- Disable AltiVec ABI extensions for the current ABI.
-
-`-mprototype'
-`-mno-prototype'
- On System V.4 and embedded PowerPC systems assume that all calls to
- variable argument functions are properly prototyped. Otherwise,
- the compiler must insert an instruction before every non
- prototyped call to set or clear bit 6 of the condition code
- register (CR) to indicate whether floating point values were
- passed in the floating point registers in case the function takes
- a variable arguments. With `-mprototype', only calls to
- prototyped variable argument functions will set or clear the bit.
-
-`-msim'
- On embedded PowerPC systems, assume that the startup module is
- called `sim-crt0.o' and that the standard C libraries are
- `libsim.a' and `libc.a'. This is the default for
- `powerpc-*-eabisim'. configurations.
-
-`-mmvme'
- On embedded PowerPC systems, assume that the startup module is
- called `crt0.o' and the standard C libraries are `libmvme.a' and
- `libc.a'.
-
-`-mads'
- On embedded PowerPC systems, assume that the startup module is
- called `crt0.o' and the standard C libraries are `libads.a' and
- `libc.a'.
-
-`-myellowknife'
- On embedded PowerPC systems, assume that the startup module is
- called `crt0.o' and the standard C libraries are `libyk.a' and
- `libc.a'.
-
-`-mvxworks'
- On System V.4 and embedded PowerPC systems, specify that you are
- compiling for a VxWorks system.
-
-`-memb'
- On embedded PowerPC systems, set the PPC_EMB bit in the ELF flags
- header to indicate that `eabi' extended relocations are used.
-
-`-meabi'
-`-mno-eabi'
- On System V.4 and embedded PowerPC systems do (do not) adhere to
- the Embedded Applications Binary Interface (eabi) which is a set of
- modifications to the System V.4 specifications. Selecting `-meabi'
- means that the stack is aligned to an 8 byte boundary, a function
- `__eabi' is called to from `main' to set up the eabi environment,
- and the `-msdata' option can use both `r2' and `r13' to point to
- two separate small data areas. Selecting `-mno-eabi' means that
- the stack is aligned to a 16 byte boundary, do not call an
- initialization function from `main', and the `-msdata' option will
- only use `r13' to point to a single small data area. The `-meabi'
- option is on by default if you configured GCC using one of the
- `powerpc*-*-eabi*' options.
-
-`-msdata=eabi'
- On System V.4 and embedded PowerPC systems, put small initialized
- `const' global and static data in the `.sdata2' section, which is
- pointed to by register `r2'. Put small initialized non-`const'
- global and static data in the `.sdata' section, which is pointed
- to by register `r13'. Put small uninitialized global and static
- data in the `.sbss' section, which is adjacent to the `.sdata'
- section. The `-msdata=eabi' option is incompatible with the
- `-mrelocatable' option. The `-msdata=eabi' option also sets the
- `-memb' option.
-
-`-msdata=sysv'
- On System V.4 and embedded PowerPC systems, put small global and
- static data in the `.sdata' section, which is pointed to by
- register `r13'. Put small uninitialized global and static data in
- the `.sbss' section, which is adjacent to the `.sdata' section.
- The `-msdata=sysv' option is incompatible with the `-mrelocatable'
- option.
-
-`-msdata=default'
-`-msdata'
- On System V.4 and embedded PowerPC systems, if `-meabi' is used,
- compile code the same as `-msdata=eabi', otherwise compile code the
- same as `-msdata=sysv'.
-
-`-msdata-data'
- On System V.4 and embedded PowerPC systems, put small global and
- static data in the `.sdata' section. Put small uninitialized
- global and static data in the `.sbss' section. Do not use
- register `r13' to address small data however. This is the default
- behavior unless other `-msdata' options are used.
-
-`-msdata=none'
-`-mno-sdata'
- On embedded PowerPC systems, put all initialized global and static
- data in the `.data' section, and all uninitialized data in the
- `.bss' section.
-
-`-G NUM'
- On embedded PowerPC systems, put global and static items less than
- or equal to NUM bytes into the small data or bss sections instead
- of the normal data or bss section. By default, NUM is 8. The `-G
- NUM' switch is also passed to the linker. All modules should be
- compiled with the same `-G NUM' value.
-
-`-mregnames'
-`-mno-regnames'
- On System V.4 and embedded PowerPC systems do (do not) emit
- register names in the assembly language output using symbolic
- forms.
-
-`-pthread'
- Adds support for multithreading with the "pthreads" library. This
- option sets flags for both the preprocessor and linker.
-
-
-\1f
-File: gcc.info, Node: RT Options, Next: MIPS Options, Prev: RS/6000 and PowerPC Options, Up: Submodel Options
-
-IBM RT Options
---------------
-
- These `-m' options are defined for the IBM RT PC:
-
-`-min-line-mul'
- Use an in-line code sequence for integer multiplies. This is the
- default.
-
-`-mcall-lib-mul'
- Call `lmul$$' for integer multiples.
-
-`-mfull-fp-blocks'
- Generate full-size floating point data blocks, including the
- minimum amount of scratch space recommended by IBM. This is the
- default.
-
-`-mminimum-fp-blocks'
- Do not include extra scratch space in floating point data blocks.
- This results in smaller code, but slower execution, since scratch
- space must be allocated dynamically.
-
-`-mfp-arg-in-fpregs'
- Use a calling sequence incompatible with the IBM calling
- convention in which floating point arguments are passed in
- floating point registers. Note that `varargs.h' and `stdarg.h'
- will not work with floating point operands if this option is
- specified.
-
-`-mfp-arg-in-gregs'
- Use the normal calling convention for floating point arguments.
- This is the default.
-
-`-mhc-struct-return'
- Return structures of more than one word in memory, rather than in a
- register. This provides compatibility with the MetaWare HighC (hc)
- compiler. Use the option `-fpcc-struct-return' for compatibility
- with the Portable C Compiler (pcc).
-
-`-mnohc-struct-return'
- Return some structures of more than one word in registers, when
- convenient. This is the default. For compatibility with the
- IBM-supplied compilers, use the option `-fpcc-struct-return' or the
- option `-mhc-struct-return'.
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: MIPS Options, Next: i386 and x86-64 Options, Prev: RT Options, Up: Submodel Options
-
-MIPS Options
-------------
-
- These `-m' options are defined for the MIPS family of computers:
-
-`-march=CPU-TYPE'
- Assume the defaults for the machine type CPU-TYPE when generating
- instructions. The choices for CPU-TYPE are `r2000', `r3000',
- `r3900', `r4000', `r4100', `r4300', `r4400', `r4600', `r4650',
- `r5000', `r6000', `r8000', and `orion'. Additionally, the
- `r2000', `r3000', `r4000', `r5000', and `r6000' can be abbreviated
- as `r2k' (or `r2K'), `r3k', etc.
-
-`-mtune=CPU-TYPE'
- Assume the defaults for the machine type CPU-TYPE when scheduling
- instructions. The choices for CPU-TYPE are `r2000', `r3000',
- `r3900', `r4000', `r4100', `r4300', `r4400', `r4600', `r4650',
- `r5000', `r6000', `r8000', and `orion'. Additionally, the
- `r2000', `r3000', `r4000', `r5000', and `r6000' can be abbreviated
- as `r2k' (or `r2K'), `r3k', etc. While picking a specific
- CPU-TYPE will schedule things appropriately for that particular
- chip, the compiler will not generate any code that does not meet
- level 1 of the MIPS ISA (instruction set architecture) without a
- `-mipsX' or `-mabi' switch being used.
-
-`-mcpu=CPU-TYPE'
- This is identical to specifying both `-march' and `-mtune'.
-
-`-mips1'
- Issue instructions from level 1 of the MIPS ISA. This is the
- default. `r3000' is the default CPU-TYPE at this ISA level.
-
-`-mips2'
- Issue instructions from level 2 of the MIPS ISA (branch likely,
- square root instructions). `r6000' is the default CPU-TYPE at this
- ISA level.
-
-`-mips3'
- Issue instructions from level 3 of the MIPS ISA (64-bit
- instructions). `r4000' is the default CPU-TYPE at this ISA level.
-
-`-mips4'
- Issue instructions from level 4 of the MIPS ISA (conditional move,
- prefetch, enhanced FPU instructions). `r8000' is the default
- CPU-TYPE at this ISA level.
-
-`-mfp32'
- Assume that 32 32-bit floating point registers are available.
- This is the default.
-
-`-mfp64'
- Assume that 32 64-bit floating point registers are available.
- This is the default when the `-mips3' option is used.
-
-`-mfused-madd'
-`-mno-fused-madd'
- Generate code that uses (does not use) the floating point multiply
- and accumulate instructions, when they are available. These
- instructions are generated by default if they are available, but
- this may be undesirable if the extra precision causes problems or
- on certain chips in the mode where denormals are rounded to zero
- where denormals generated by multiply and accumulate instructions
- cause exceptions anyway.
-
-`-mgp32'
- Assume that 32 32-bit general purpose registers are available.
- This is the default.
-
-`-mgp64'
- Assume that 32 64-bit general purpose registers are available.
- This is the default when the `-mips3' option is used.
-
-`-mint64'
- Force int and long types to be 64 bits wide. See `-mlong32' for an
- explanation of the default, and the width of pointers.
-
-`-mlong64'
- Force long types to be 64 bits wide. See `-mlong32' for an
- explanation of the default, and the width of pointers.
-
-`-mlong32'
- Force long, int, and pointer types to be 32 bits wide.
-
- If none of `-mlong32', `-mlong64', or `-mint64' are set, the size
- of ints, longs, and pointers depends on the ABI and ISA chosen.
- For `-mabi=32', and `-mabi=n32', ints and longs are 32 bits wide.
- For `-mabi=64', ints are 32 bits, and longs are 64 bits wide. For
- `-mabi=eabi' and either `-mips1' or `-mips2', ints and longs are
- 32 bits wide. For `-mabi=eabi' and higher ISAs, ints are 32 bits,
- and longs are 64 bits wide. The width of pointer types is the
- smaller of the width of longs or the width of general purpose
- registers (which in turn depends on the ISA).
-
-`-mabi=32'
-`-mabi=o64'
-`-mabi=n32'
-`-mabi=64'
-`-mabi=eabi'
- Generate code for the indicated ABI. The default instruction
- level is `-mips1' for `32', `-mips3' for `n32', and `-mips4'
- otherwise. Conversely, with `-mips1' or `-mips2', the default ABI
- is `32'; otherwise, the default ABI is `64'.
-
-`-mmips-as'
- Generate code for the MIPS assembler, and invoke `mips-tfile' to
- add normal debug information. This is the default for all
- platforms except for the OSF/1 reference platform, using the
- OSF/rose object format. If the either of the `-gstabs' or
- `-gstabs+' switches are used, the `mips-tfile' program will
- encapsulate the stabs within MIPS ECOFF.
-
-`-mgas'
- Generate code for the GNU assembler. This is the default on the
- OSF/1 reference platform, using the OSF/rose object format. Also,
- this is the default if the configure option `--with-gnu-as' is
- used.
-
-`-msplit-addresses'
-`-mno-split-addresses'
- Generate code to load the high and low parts of address constants
- separately. This allows GCC to optimize away redundant loads of
- the high order bits of addresses. This optimization requires GNU
- as and GNU ld. This optimization is enabled by default for some
- embedded targets where GNU as and GNU ld are standard.
-
-`-mrnames'
-`-mno-rnames'
- The `-mrnames' switch says to output code using the MIPS software
- names for the registers, instead of the hardware names (ie, A0
- instead of $4). The only known assembler that supports this option
- is the Algorithmics assembler.
-
-`-mgpopt'
-`-mno-gpopt'
- The `-mgpopt' switch says to write all of the data declarations
- before the instructions in the text section, this allows the MIPS
- assembler to generate one word memory references instead of using
- two words for short global or static data items. This is on by
- default if optimization is selected.
-
-`-mstats'
-`-mno-stats'
- For each non-inline function processed, the `-mstats' switch
- causes the compiler to emit one line to the standard error file to
- print statistics about the program (number of registers saved,
- stack size, etc.).
-
-`-mmemcpy'
-`-mno-memcpy'
- The `-mmemcpy' switch makes all block moves call the appropriate
- string function (`memcpy' or `bcopy') instead of possibly
- generating inline code.
-
-`-mmips-tfile'
-`-mno-mips-tfile'
- The `-mno-mips-tfile' switch causes the compiler not postprocess
- the object file with the `mips-tfile' program, after the MIPS
- assembler has generated it to add debug support. If `mips-tfile'
- is not run, then no local variables will be available to the
- debugger. In addition, `stage2' and `stage3' objects will have
- the temporary file names passed to the assembler embedded in the
- object file, which means the objects will not compare the same.
- The `-mno-mips-tfile' switch should only be used when there are
- bugs in the `mips-tfile' program that prevents compilation.
-
-`-msoft-float'
- Generate output containing library calls for floating point.
- *Warning:* the requisite libraries are not part of GCC. Normally
- the facilities of the machine's usual C compiler are used, but
- this can't be done directly in cross-compilation. You must make
- your own arrangements to provide suitable library functions for
- cross-compilation.
-
-`-mhard-float'
- Generate output containing floating point instructions. This is
- the default if you use the unmodified sources.
-
-`-mabicalls'
-`-mno-abicalls'
- Emit (or do not emit) the pseudo operations `.abicalls',
- `.cpload', and `.cprestore' that some System V.4 ports use for
- position independent code.
-
-`-mlong-calls'
-`-mno-long-calls'
- Do all calls with the `JALR' instruction, which requires loading
- up a function's address into a register before the call. You need
- to use this switch, if you call outside of the current 512
- megabyte segment to functions that are not through pointers.
-
-`-mhalf-pic'
-`-mno-half-pic'
- Put pointers to extern references into the data section and load
- them up, rather than put the references in the text section.
-
-`-membedded-pic'
-`-mno-embedded-pic'
- Generate PIC code suitable for some embedded systems. All calls
- are made using PC relative address, and all data is addressed
- using the $gp register. No more than 65536 bytes of global data
- may be used. This requires GNU as and GNU ld which do most of the
- work. This currently only works on targets which use ECOFF; it
- does not work with ELF.
-
-`-membedded-data'
-`-mno-embedded-data'
- Allocate variables to the read-only data section first if
- possible, then next in the small data section if possible,
- otherwise in data. This gives slightly slower code than the
- default, but reduces the amount of RAM required when executing,
- and thus may be preferred for some embedded systems.
-
-`-muninit-const-in-rodata'
-`-mno-uninit-const-in-rodata'
- When used together with `-membedded-data', it will always store
- uninitialized const variables in the read-only data section.
-
-`-msingle-float'
-`-mdouble-float'
- The `-msingle-float' switch tells gcc to assume that the floating
- point coprocessor only supports single precision operations, as on
- the `r4650' chip. The `-mdouble-float' switch permits gcc to use
- double precision operations. This is the default.
-
-`-mmad'
-`-mno-mad'
- Permit use of the `mad', `madu' and `mul' instructions, as on the
- `r4650' chip.
-
-`-m4650'
- Turns on `-msingle-float', `-mmad', and, at least for now,
- `-mcpu=r4650'.
-
-`-mips16'
-`-mno-mips16'
- Enable 16-bit instructions.
-
-`-mentry'
- Use the entry and exit pseudo ops. This option can only be used
- with `-mips16'.
-
-`-EL'
- Compile code for the processor in little endian mode. The
- requisite libraries are assumed to exist.
-
-`-EB'
- Compile code for the processor in big endian mode. The requisite
- libraries are assumed to exist.
-
-`-G NUM'
- Put global and static items less than or equal to NUM bytes into
- the small data or bss sections instead of the normal data or bss
- section. This allows the assembler to emit one word memory
- reference instructions based on the global pointer (GP or $28),
- instead of the normal two words used. By default, NUM is 8 when
- the MIPS assembler is used, and 0 when the GNU assembler is used.
- The `-G NUM' switch is also passed to the assembler and linker.
- All modules should be compiled with the same `-G NUM' value.
-
-`-nocpp'
- Tell the MIPS assembler to not run its preprocessor over user
- assembler files (with a `.s' suffix) when assembling them.
-
-`-mfix7000'
- Pass an option to gas which will cause nops to be inserted if the
- read of the destination register of an mfhi or mflo instruction
- occurs in the following two instructions.
-
-`-no-crt0'
- Do not include the default crt0.
-
-`-mflush-func=FUNC'
-`-mno-flush-func'
- Specifies the function to call to flush the I and D caches, or to
- not call any such function. If called, the function must take the
- same arguments as the common `_flush_func()', that is, the address
- of the memory range for which the cache is being flushed, the size
- of the memory range, and the number 3 (to flush both caches). The
- default depends on the target gcc was configured for, but commonly
- is either `_flush_func' or `__cpu_flush'.
-
- These options are defined by the macro `TARGET_SWITCHES' in the
-machine description. The default for the options is also defined by
-that macro, which enables you to change the defaults.
-
-\1f
-File: gcc.info, Node: i386 and x86-64 Options, Next: HPPA Options, Prev: MIPS Options, Up: Submodel Options
-
-Intel 386 and AMD x86-64 Options
---------------------------------
-
- These `-m' options are defined for the i386 and x86-64 family of
-computers:
-
-`-mcpu=CPU-TYPE'
- Tune to CPU-TYPE everything applicable about the generated code,
- except for the ABI and the set of available instructions. The
- choices for CPU-TYPE are `i386', `i486', `i586', `i686',
- `pentium', `pentium-mmx', `pentiumpro', `pentium2', `pentium3',
- `pentium4', `k6', `k6-2', `k6-3', `athlon', `athlon-tbird',
- `athlon-4', `athlon-xp' and `athlon-mp'.
-
- While picking a specific CPU-TYPE will schedule things
- appropriately for that particular chip, the compiler will not
- generate any code that does not run on the i386 without the
- `-march=CPU-TYPE' option being used. `i586' is equivalent to
- `pentium' and `i686' is equivalent to `pentiumpro'. `k6' and
- `athlon' are the AMD chips as opposed to the Intel ones.
-
-`-march=CPU-TYPE'
- Generate instructions for the machine type CPU-TYPE. The choices
- for CPU-TYPE are the same as for `-mcpu'. Moreover, specifying
- `-march=CPU-TYPE' implies `-mcpu=CPU-TYPE'.
-
-`-m386'
-`-m486'
-`-mpentium'
-`-mpentiumpro'
- These options are synonyms for `-mcpu=i386', `-mcpu=i486',
- `-mcpu=pentium', and `-mcpu=pentiumpro' respectively. These
- synonyms are deprecated.
-
-`-mfpmath=UNIT'
- generate floating point arithmetics for selected unit UNIT. the
- choices for UNIT are:
-
- `387'
- Use the standard 387 floating point coprocessor present
- majority of chips and emulated otherwise. Code compiled with
- this option will run almost everywhere. The temporary
- results are computed in 80bit precesion instead of precision
- specified by the type resulting in slightly different results
- compared to most of other chips. See `-ffloat-store' for more
- detailed description.
-
- This is the default choice for i386 compiler.
-
- `sse'
- Use scalar floating point instructions present in the SSE
- instruction set. This instruction set is supported by
- Pentium3 and newer chips, in the AMD line by Athlon-4,
- Athlon-xp and Athlon-mp chips. The earlier version of SSE
- instruction set supports only single precision arithmetics,
- thus the double and extended precision arithmetics is still
- done using 387. Later version, present only in Pentium4 and
- the future AMD x86-64 chips supports double precision
- arithmetics too.
-
- For i387 you need to use `-march=CPU-TYPE', `-msse' or
- `-msse2' switches to enable SSE extensions and make this
- option effective. For x86-64 compiler, these extensions are
- enabled by default.
-
- The resulting code should be considerably faster in majority
- of cases and avoid the numerical instability problems of 387
- code, but may break some existing code that expects
- temporaries to be 80bit.
-
- This is the default choice for x86-64 compiler.
-
- `sse,387'
- Attempt to utilize both instruction sets at once. This
- effectivly double the amount of available registers and on
- chips with separate execution units for 387 and SSE the
- execution resources too. Use this option with care, as it is
- still experimental, because gcc register allocator does not
- model separate functional units well resulting in instable
- performance.
-
-`-masm=DIALECT'
- Output asm instructions using selected DIALECT. Supported choices
- are `intel' or `att' (the default one).
-
-`-mieee-fp'
-`-mno-ieee-fp'
- Control whether or not the compiler uses IEEE floating point
- comparisons. These handle correctly the case where the result of a
- comparison is unordered.
-
-`-msoft-float'
- Generate output containing library calls for floating point.
- *Warning:* the requisite libraries are not part of GCC. Normally
- the facilities of the machine's usual C compiler are used, but
- this can't be done directly in cross-compilation. You must make
- your own arrangements to provide suitable library functions for
- cross-compilation.
-
- On machines where a function returns floating point results in the
- 80387 register stack, some floating point opcodes may be emitted
- even if `-msoft-float' is used.
-
-`-mno-fp-ret-in-387'
- Do not use the FPU registers for return values of functions.
-
- The usual calling convention has functions return values of types
- `float' and `double' in an FPU register, even if there is no FPU.
- The idea is that the operating system should emulate an FPU.
-
- The option `-mno-fp-ret-in-387' causes such values to be returned
- in ordinary CPU registers instead.
-
-`-mno-fancy-math-387'
- Some 387 emulators do not support the `sin', `cos' and `sqrt'
- instructions for the 387. Specify this option to avoid generating
- those instructions. This option is the default on FreeBSD,
- OpenBSD and NetBSD. This option is overridden when `-march'
- indicates that the target cpu will always have an FPU and so the
- instruction will not need emulation. As of revision 2.6.1, these
- instructions are not generated unless you also use the
- `-funsafe-math-optimizations' switch.
-
-`-malign-double'
-`-mno-align-double'
- Control whether GCC aligns `double', `long double', and `long
- long' variables on a two word boundary or a one word boundary.
- Aligning `double' variables on a two word boundary will produce
- code that runs somewhat faster on a `Pentium' at the expense of
- more memory.
-
- *Warning:* if you use the `-malign-double' switch, structures
- containing the above types will be aligned differently than the
- published application binary interface specifications for the 386
- and will not be binary compatible with structures in code compiled
- without that switch.
-
-`-m128bit-long-double'
- Control the size of `long double' type. i386 application binary
- interface specify the size to be 12 bytes, while modern
- architectures (Pentium and newer) prefer `long double' aligned to
- 8 or 16 byte boundary. This is impossible to reach with 12 byte
- long doubles in the array accesses.
-
- *Warning:* if you use the `-m128bit-long-double' switch, the
- structures and arrays containing `long double' will change their
- size as well as function calling convention for function taking
- `long double' will be modified.
-
-`-m96bit-long-double'
- Set the size of `long double' to 96 bits as required by the i386
- application binary interface. This is the default.
-
-`-msvr3-shlib'
-`-mno-svr3-shlib'
- Control whether GCC places uninitialized local variables into the
- `bss' or `data' segments. `-msvr3-shlib' places them into `bss'.
- These options are meaningful only on System V Release 3.
-
-`-mrtd'
- Use a different function-calling convention, in which functions
- that take a fixed number of arguments return with the `ret' NUM
- instruction, which pops their arguments while returning. This
- saves one instruction in the caller since there is no need to pop
- the arguments there.
-
- You can specify that an individual function is called with this
- calling sequence with the function attribute `stdcall'. You can
- also override the `-mrtd' option by using the function attribute
- `cdecl'. *Note Function Attributes::.
-
- *Warning:* this calling convention is incompatible with the one
- normally used on Unix, so you cannot use it if you need to call
- libraries compiled with the Unix compiler.
-
- Also, you must provide function prototypes for all functions that
- take variable numbers of arguments (including `printf'); otherwise
- incorrect code will be generated for calls to those functions.
-
- In addition, seriously incorrect code will result if you call a
- function with too many arguments. (Normally, extra arguments are
- harmlessly ignored.)
-
-`-mregparm=NUM'
- Control how many registers are used to pass integer arguments. By
- default, no registers are used to pass arguments, and at most 3
- registers can be used. You can control this behavior for a
- specific function by using the function attribute `regparm'.
- *Note Function Attributes::.
-
- *Warning:* if you use this switch, and NUM is nonzero, then you
- must build all modules with the same value, including any
- libraries. This includes the system libraries and startup modules.
-
-`-mpreferred-stack-boundary=NUM'
- Attempt to keep the stack boundary aligned to a 2 raised to NUM
- byte boundary. If `-mpreferred-stack-boundary' is not specified,
- the default is 4 (16 bytes or 128 bits), except when optimizing
- for code size (`-Os'), in which case the default is the minimum
- correct alignment (4 bytes for x86, and 8 bytes for x86-64).
-
- On Pentium and PentiumPro, `double' and `long double' values
- should be aligned to an 8 byte boundary (see `-malign-double') or
- suffer significant run time performance penalties. On Pentium
- III, the Streaming SIMD Extension (SSE) data type `__m128' suffers
- similar penalties if it is not 16 byte aligned.
-
- To ensure proper alignment of this values on the stack, the stack
- boundary must be as aligned as that required by any value stored
- on the stack. Further, every function must be generated such that
- it keeps the stack aligned. Thus calling a function compiled with
- a higher preferred stack boundary from a function compiled with a
- lower preferred stack boundary will most likely misalign the
- stack. It is recommended that libraries that use callbacks always
- use the default setting.
-
- This extra alignment does consume extra stack space, and generally
- increases code size. Code that is sensitive to stack space usage,
- such as embedded systems and operating system kernels, may want to
- reduce the preferred alignment to `-mpreferred-stack-boundary=2'.
-
-`-mmmx'
-`-mno-mmx'
-
-`-msse'
-`-mno-sse'
-
-`-msse2'
-`-mno-sse2'
-
-`-m3dnow'
-`-mno-3dnow'
- These switches enable or disable the use of built-in functions
- that allow direct access to the MMX, SSE and 3Dnow extensions of
- the instruction set.
-
- *Note X86 Built-in Functions::, for details of the functions
- enabled and disabled by these switches.
-
- To have SSE/SSE2 instructions generated automatically from
- floating-point code, see `-mfpmath=sse'.
-
-`-mpush-args'
-`-mno-push-args'
- Use PUSH operations to store outgoing parameters. This method is
- shorter and usually equally fast as method using SUB/MOV
- operations and is enabled by default. In some cases disabling it
- may improve performance because of improved scheduling and reduced
- dependencies.
-
-`-maccumulate-outgoing-args'
- If enabled, the maximum amount of space required for outgoing
- arguments will be computed in the function prologue. This is
- faster on most modern CPUs because of reduced dependencies,
- improved scheduling and reduced stack usage when preferred stack
- boundary is not equal to 2. The drawback is a notable increase in
- code size. This switch implies `-mno-push-args'.
-
-`-mthreads'
- Support thread-safe exception handling on `Mingw32'. Code that
- relies on thread-safe exception handling must compile and link all
- code with the `-mthreads' option. When compiling, `-mthreads'
- defines `-D_MT'; when linking, it links in a special thread helper
- library `-lmingwthrd' which cleans up per thread exception
- handling data.
-
-`-mno-align-stringops'
- Do not align destination of inlined string operations. This
- switch reduces code size and improves performance in case the
- destination is already aligned, but gcc don't know about it.
-
-`-minline-all-stringops'
- By default GCC inlines string operations only when destination is
- known to be aligned at least to 4 byte boundary. This enables
- more inlining, increase code size, but may improve performance of
- code that depends on fast memcpy, strlen and memset for short
- lengths.
-
-`-momit-leaf-frame-pointer'
- Don't keep the frame pointer in a register for leaf functions.
- This avoids the instructions to save, set up and restore frame
- pointers and makes an extra register available in leaf functions.
- The option `-fomit-frame-pointer' removes the frame pointer for
- all functions which might make debugging harder.
-
- These `-m' switches are supported in addition to the above on AMD
-x86-64 processors in 64-bit environments.
-
-`-m32'
-`-m64'
- Generate code for a 32-bit or 64-bit environment. The 32-bit
- environment sets int, long and pointer to 32 bits and generates
- code that runs on any i386 system. The 64-bit environment sets
- int to 32 bits and long and pointer to 64 bits and generates code
- for AMD's x86-64 architecture.
-
-`-mno-red-zone'
- Do not use a so called red zone for x86-64 code. The red zone is
- mandated by the x86-64 ABI, it is a 128-byte area beyond the
- location of the stack pointer that will not be modified by signal
- or interrupt handlers and therefore can be used for temporary data
- without adjusting the stack pointer. The flag `-mno-red-zone'
- disables this red zone.
-
-`-mcmodel=small'
- Generate code for the small code model: the program and its
- symbols must be linked in the lower 2 GB of the address space.
- Pointers are 64 bits. Programs can be statically or dynamically
- linked. This is the default code model.
-
-`-mcmodel=kernel'
- Generate code for the kernel code model. The kernel runs in the
- negative 2 GB of the address space. This model has to be used for
- Linux kernel code.
-
-`-mcmodel=medium'
- Generate code for the medium model: The program is linked in the
- lower 2 GB of the address space but symbols can be located
- anywhere in the address space. Programs can be statically or
- dynamically linked, but building of shared libraries are not
- supported with the medium model.
-
-`-mcmodel=large'
- Generate code for the large model: This model makes no assumptions
- about addresses and sizes of sections. Currently GCC does not
- implement this model.
-
-\1f
-File: gcc.info, Node: HPPA Options, Next: Intel 960 Options, Prev: i386 and x86-64 Options, Up: Submodel Options
-
-HPPA Options
-------------
-
- These `-m' options are defined for the HPPA family of computers:
-
-`-march=ARCHITECTURE-TYPE'
- Generate code for the specified architecture. The choices for
- ARCHITECTURE-TYPE are `1.0' for PA 1.0, `1.1' for PA 1.1, and
- `2.0' for PA 2.0 processors. Refer to `/usr/lib/sched.models' on
- an HP-UX system to determine the proper architecture option for
- your machine. Code compiled for lower numbered architectures will
- run on higher numbered architectures, but not the other way around.
-
- PA 2.0 support currently requires gas snapshot 19990413 or later.
- The next release of binutils (current is 2.9.1) will probably
- contain PA 2.0 support.
-
-`-mpa-risc-1-0'
-`-mpa-risc-1-1'
-`-mpa-risc-2-0'
- Synonyms for `-march=1.0', `-march=1.1', and `-march=2.0'
- respectively.
-
-`-mbig-switch'
- Generate code suitable for big switch tables. Use this option
- only if the assembler/linker complain about out of range branches
- within a switch table.
-
-`-mjump-in-delay'
- Fill delay slots of function calls with unconditional jump
- instructions by modifying the return pointer for the function call
- to be the target of the conditional jump.
-
-`-mdisable-fpregs'
- Prevent floating point registers from being used in any manner.
- This is necessary for compiling kernels which perform lazy context
- switching of floating point registers. If you use this option and
- attempt to perform floating point operations, the compiler will
- abort.
-
-`-mdisable-indexing'
- Prevent the compiler from using indexing address modes. This
- avoids some rather obscure problems when compiling MIG generated
- code under MACH.
-
-`-mno-space-regs'
- Generate code that assumes the target has no space registers.
- This allows GCC to generate faster indirect calls and use unscaled
- index address modes.
-
- Such code is suitable for level 0 PA systems and kernels.
-
-`-mfast-indirect-calls'
- Generate code that assumes calls never cross space boundaries.
- This allows GCC to emit code which performs faster indirect calls.
-
- This option will not work in the presence of shared libraries or
- nested functions.
-
-`-mlong-load-store'
- Generate 3-instruction load and store sequences as sometimes
- required by the HP-UX 10 linker. This is equivalent to the `+k'
- option to the HP compilers.
-
-`-mportable-runtime'
- Use the portable calling conventions proposed by HP for ELF
- systems.
-
-`-mgas'
- Enable the use of assembler directives only GAS understands.
-
-`-mschedule=CPU-TYPE'
- Schedule code according to the constraints for the machine type
- CPU-TYPE. The choices for CPU-TYPE are `700' `7100', `7100LC',
- `7200', and `8000'. Refer to `/usr/lib/sched.models' on an HP-UX
- system to determine the proper scheduling option for your machine.
-
-`-mlinker-opt'
- Enable the optimization pass in the HPUX linker. Note this makes
- symbolic debugging impossible. It also triggers a bug in the HPUX
- 8 and HPUX 9 linkers in which they give bogus error messages when
- linking some programs.
-
-`-msoft-float'
- Generate output containing library calls for floating point.
- *Warning:* the requisite libraries are not available for all HPPA
- targets. Normally the facilities of the machine's usual C
- compiler are used, but this cannot be done directly in
- cross-compilation. You must make your own arrangements to provide
- suitable library functions for cross-compilation. The embedded
- target `hppa1.1-*-pro' does provide software floating point
- support.
-
- `-msoft-float' changes the calling convention in the output file;
- therefore, it is only useful if you compile _all_ of a program with
- this option. In particular, you need to compile `libgcc.a', the
- library that comes with GCC, with `-msoft-float' in order for this
- to work.
-
-\1f
-File: gcc.info, Node: Intel 960 Options, Next: DEC Alpha Options, Prev: HPPA Options, Up: Submodel Options
-
-Intel 960 Options
------------------
-
- These `-m' options are defined for the Intel 960 implementations:
-
-`-mCPU-TYPE'
- Assume the defaults for the machine type CPU-TYPE for some of the
- other options, including instruction scheduling, floating point
- support, and addressing modes. The choices for CPU-TYPE are `ka',
- `kb', `mc', `ca', `cf', `sa', and `sb'. The default is `kb'.
-
-`-mnumerics'
-`-msoft-float'
- The `-mnumerics' option indicates that the processor does support
- floating-point instructions. The `-msoft-float' option indicates
- that floating-point support should not be assumed.
-
-`-mleaf-procedures'
-`-mno-leaf-procedures'
- Do (or do not) attempt to alter leaf procedures to be callable
- with the `bal' instruction as well as `call'. This will result in
- more efficient code for explicit calls when the `bal' instruction
- can be substituted by the assembler or linker, but less efficient
- code in other cases, such as calls via function pointers, or using
- a linker that doesn't support this optimization.
-
-`-mtail-call'
-`-mno-tail-call'
- Do (or do not) make additional attempts (beyond those of the
- machine-independent portions of the compiler) to optimize
- tail-recursive calls into branches. You may not want to do this
- because the detection of cases where this is not valid is not
- totally complete. The default is `-mno-tail-call'.
-
-`-mcomplex-addr'
-`-mno-complex-addr'
- Assume (or do not assume) that the use of a complex addressing
- mode is a win on this implementation of the i960. Complex
- addressing modes may not be worthwhile on the K-series, but they
- definitely are on the C-series. The default is currently
- `-mcomplex-addr' for all processors except the CB and CC.
-
-`-mcode-align'
-`-mno-code-align'
- Align code to 8-byte boundaries for faster fetching (or don't
- bother). Currently turned on by default for C-series
- implementations only.
-
-`-mic-compat'
-`-mic2.0-compat'
-`-mic3.0-compat'
- Enable compatibility with iC960 v2.0 or v3.0.
-
-`-masm-compat'
-`-mintel-asm'
- Enable compatibility with the iC960 assembler.
-
-`-mstrict-align'
-`-mno-strict-align'
- Do not permit (do permit) unaligned accesses.
-
-`-mold-align'
- Enable structure-alignment compatibility with Intel's gcc release
- version 1.3 (based on gcc 1.37). This option implies
- `-mstrict-align'.
-
-`-mlong-double-64'
- Implement type `long double' as 64-bit floating point numbers.
- Without the option `long double' is implemented by 80-bit floating
- point numbers. The only reason we have it because there is no
- 128-bit `long double' support in `fp-bit.c' yet. So it is only
- useful for people using soft-float targets. Otherwise, we should
- recommend against use of it.
-
-
-\1f
-File: gcc.info, Node: DEC Alpha Options, Next: DEC Alpha/VMS Options, Prev: Intel 960 Options, Up: Submodel Options
-
-DEC Alpha Options
------------------
-
- These `-m' options are defined for the DEC Alpha implementations:
-
-`-mno-soft-float'
-`-msoft-float'
- Use (do not use) the hardware floating-point instructions for
- floating-point operations. When `-msoft-float' is specified,
- functions in `libgcc.a' will be used to perform floating-point
- operations. Unless they are replaced by routines that emulate the
- floating-point operations, or compiled in such a way as to call
- such emulations routines, these routines will issue floating-point
- operations. If you are compiling for an Alpha without
- floating-point operations, you must ensure that the library is
- built so as not to call them.
-
- Note that Alpha implementations without floating-point operations
- are required to have floating-point registers.
-
-`-mfp-reg'
-`-mno-fp-regs'
- Generate code that uses (does not use) the floating-point register
- set. `-mno-fp-regs' implies `-msoft-float'. If the floating-point
- register set is not used, floating point operands are passed in
- integer registers as if they were integers and floating-point
- results are passed in `$0' instead of `$f0'. This is a
- non-standard calling sequence, so any function with a
- floating-point argument or return value called by code compiled
- with `-mno-fp-regs' must also be compiled with that option.
-
- A typical use of this option is building a kernel that does not
- use, and hence need not save and restore, any floating-point
- registers.
-
-`-mieee'
- The Alpha architecture implements floating-point hardware
- optimized for maximum performance. It is mostly compliant with
- the IEEE floating point standard. However, for full compliance,
- software assistance is required. This option generates code fully
- IEEE compliant code _except_ that the INEXACT-FLAG is not
- maintained (see below). If this option is turned on, the
- preprocessor macro `_IEEE_FP' is defined during compilation. The
- resulting code is less efficient but is able to correctly support
- denormalized numbers and exceptional IEEE values such as
- not-a-number and plus/minus infinity. Other Alpha compilers call
- this option `-ieee_with_no_inexact'.
-
-`-mieee-with-inexact'
- This is like `-mieee' except the generated code also maintains the
- IEEE INEXACT-FLAG. Turning on this option causes the generated
- code to implement fully-compliant IEEE math. In addition to
- `_IEEE_FP', `_IEEE_FP_EXACT' is defined as a preprocessor macro.
- On some Alpha implementations the resulting code may execute
- significantly slower than the code generated by default. Since
- there is very little code that depends on the INEXACT-FLAG, you
- should normally not specify this option. Other Alpha compilers
- call this option `-ieee_with_inexact'.
-
-`-mfp-trap-mode=TRAP-MODE'
- This option controls what floating-point related traps are enabled.
- Other Alpha compilers call this option `-fptm TRAP-MODE'. The
- trap mode can be set to one of four values:
-
- `n'
- This is the default (normal) setting. The only traps that
- are enabled are the ones that cannot be disabled in software
- (e.g., division by zero trap).
-
- `u'
- In addition to the traps enabled by `n', underflow traps are
- enabled as well.
-
- `su'
- Like `su', but the instructions are marked to be safe for
- software completion (see Alpha architecture manual for
- details).
-
- `sui'
- Like `su', but inexact traps are enabled as well.
-
-`-mfp-rounding-mode=ROUNDING-MODE'
- Selects the IEEE rounding mode. Other Alpha compilers call this
- option `-fprm ROUNDING-MODE'. The ROUNDING-MODE can be one of:
-
- `n'
- Normal IEEE rounding mode. Floating point numbers are
- rounded towards the nearest machine number or towards the
- even machine number in case of a tie.
-
- `m'
- Round towards minus infinity.
-
- `c'
- Chopped rounding mode. Floating point numbers are rounded
- towards zero.
-
- `d'
- Dynamic rounding mode. A field in the floating point control
- register (FPCR, see Alpha architecture reference manual)
- controls the rounding mode in effect. The C library
- initializes this register for rounding towards plus infinity.
- Thus, unless your program modifies the FPCR, `d' corresponds
- to round towards plus infinity.
-
-`-mtrap-precision=TRAP-PRECISION'
- In the Alpha architecture, floating point traps are imprecise.
- This means without software assistance it is impossible to recover
- from a floating trap and program execution normally needs to be
- terminated. GCC can generate code that can assist operating
- system trap handlers in determining the exact location that caused
- a floating point trap. Depending on the requirements of an
- application, different levels of precisions can be selected:
-
- `p'
- Program precision. This option is the default and means a
- trap handler can only identify which program caused a
- floating point exception.
-
- `f'
- Function precision. The trap handler can determine the
- function that caused a floating point exception.
-
- `i'
- Instruction precision. The trap handler can determine the
- exact instruction that caused a floating point exception.
-
- Other Alpha compilers provide the equivalent options called
- `-scope_safe' and `-resumption_safe'.
-
-`-mieee-conformant'
- This option marks the generated code as IEEE conformant. You must
- not use this option unless you also specify `-mtrap-precision=i'
- and either `-mfp-trap-mode=su' or `-mfp-trap-mode=sui'. Its only
- effect is to emit the line `.eflag 48' in the function prologue of
- the generated assembly file. Under DEC Unix, this has the effect
- that IEEE-conformant math library routines will be linked in.
-
-`-mbuild-constants'
- Normally GCC examines a 32- or 64-bit integer constant to see if
- it can construct it from smaller constants in two or three
- instructions. If it cannot, it will output the constant as a
- literal and generate code to load it from the data segment at
- runtime.
-
- Use this option to require GCC to construct _all_ integer constants
- using code, even if it takes more instructions (the maximum is
- six).
-
- You would typically use this option to build a shared library
- dynamic loader. Itself a shared library, it must relocate itself
- in memory before it can find the variables and constants in its
- own data segment.
-
-`-malpha-as'
-`-mgas'
- Select whether to generate code to be assembled by the
- vendor-supplied assembler (`-malpha-as') or by the GNU assembler
- `-mgas'.
-
-`-mbwx'
-`-mno-bwx'
-`-mcix'
-`-mno-cix'
-`-mfix'
-`-mno-fix'
-`-mmax'
-`-mno-max'
- Indicate whether GCC should generate code to use the optional BWX,
- CIX, FIX and MAX instruction sets. The default is to use the
- instruction sets supported by the CPU type specified via `-mcpu='
- option or that of the CPU on which GCC was built if none was
- specified.
-
-`-mfloat-vax'
-`-mfloat-ieee'
- Generate code that uses (does not use) VAX F and G floating point
- arithmetic instead of IEEE single and double precision.
-
-`-mexplicit-relocs'
-`-mno-explicit-relocs'
- Older Alpha assemblers provided no way to generate symbol
- relocations except via assembler macros. Use of these macros does
- not allow optimial instruction scheduling. GNU binutils as of
- version 2.12 supports a new syntax that allows the compiler to
- explicitly mark which relocations should apply to which
- instructions. This option is mostly useful for debugging, as GCC
- detects the capabilities of the assembler when it is built and
- sets the default accordingly.
-
-`-msmall-data'
-`-mlarge-data'
- When `-mexplicit-relocs' is in effect, static data is accessed via
- "gp-relative" relocations. When `-msmall-data' is used, objects 8
- bytes long or smaller are placed in a "small data area" (the
- `.sdata' and `.sbss' sections) and are accessed via 16-bit
- relocations off of the `$gp' register. This limits the size of
- the small data area to 64KB, but allows the variables to be
- directly accessed via a single instruction.
-
- The default is `-mlarge-data'. With this option the data area is
- limited to just below 2GB. Programs that require more than 2GB of
- data must use `malloc' or `mmap' to allocate the data in the heap
- instead of in the program's data segment.
-
- When generating code for shared libraries, `-fpic' implies
- `-msmall-data' and `-fPIC' implies `-mlarge-data'.
-
-`-mcpu=CPU_TYPE'
- Set the instruction set and instruction scheduling parameters for
- machine type CPU_TYPE. You can specify either the `EV' style name
- or the corresponding chip number. GCC supports scheduling
- parameters for the EV4, EV5 and EV6 family of processors and will
- choose the default values for the instruction set from the
- processor you specify. If you do not specify a processor type,
- GCC will default to the processor on which the compiler was built.
-
- Supported values for CPU_TYPE are
-
- `ev4'
-
- `ev45'
- `21064'
- Schedules as an EV4 and has no instruction set extensions.
-
- `ev5'
- `21164'
- Schedules as an EV5 and has no instruction set extensions.
-
- `ev56'
- `21164a'
- Schedules as an EV5 and supports the BWX extension.
-
- `pca56'
- `21164pc'
- `21164PC'
- Schedules as an EV5 and supports the BWX and MAX extensions.
-
- `ev6'
- `21264'
- Schedules as an EV6 and supports the BWX, FIX, and MAX
- extensions.
-
- `ev67'
-
- `21264a'
- Schedules as an EV6 and supports the BWX, CIX, FIX, and MAX
- extensions.
-
-`-mtune=CPU_TYPE'
- Set only the instruction scheduling parameters for machine type
- CPU_TYPE. The instruction set is not changed.
-
-`-mmemory-latency=TIME'
- Sets the latency the scheduler should assume for typical memory
- references as seen by the application. This number is highly
- dependent on the memory access patterns used by the application
- and the size of the external cache on the machine.
-
- Valid options for TIME are
-
- `NUMBER'
- A decimal number representing clock cycles.
-
- `L1'
- `L2'
- `L3'
- `main'
- The compiler contains estimates of the number of clock cycles
- for "typical" EV4 & EV5 hardware for the Level 1, 2 & 3 caches
- (also called Dcache, Scache, and Bcache), as well as to main
- memory. Note that L3 is only valid for EV5.
-
-
-\1f
-File: gcc.info, Node: DEC Alpha/VMS Options, Next: Clipper Options, Prev: DEC Alpha Options, Up: Submodel Options
-
-DEC Alpha/VMS Options
----------------------
-
- These `-m' options are defined for the DEC Alpha/VMS implementations:
-
-`-mvms-return-codes'
- Return VMS condition codes from main. The default is to return
- POSIX style condition (e.g. error) codes.
-
-\1f
-File: gcc.info, Node: Clipper Options, Next: H8/300 Options, Prev: DEC Alpha/VMS Options, Up: Submodel Options
-
-Clipper Options
----------------
-
- These `-m' options are defined for the Clipper implementations:
-
-`-mc300'
- Produce code for a C300 Clipper processor. This is the default.
-
-`-mc400'
- Produce code for a C400 Clipper processor, i.e. use floating point
- registers f8-f15.
-
-\1f
-File: gcc.info, Node: H8/300 Options, Next: SH Options, Prev: Clipper Options, Up: Submodel Options
-
-H8/300 Options
---------------
-
- These `-m' options are defined for the H8/300 implementations:
-
-`-mrelax'
- Shorten some address references at link time, when possible; uses
- the linker option `-relax'. *Note `ld' and the H8/300:
- (ld.info)H8/300, for a fuller description.
-
-`-mh'
- Generate code for the H8/300H.
-
-`-ms'
- Generate code for the H8/S.
-
-`-ms2600'
- Generate code for the H8/S2600. This switch must be used with
- `-ms'.
-
-`-mint32'
- Make `int' data 32 bits by default.
-
-`-malign-300'
- On the H8/300H and H8/S, use the same alignment rules as for the
- H8/300. The default for the H8/300H and H8/S is to align longs
- and floats on 4 byte boundaries. `-malign-300' causes them to be
- aligned on 2 byte boundaries. This option has no effect on the
- H8/300.
-
-\1f
-File: gcc.info, Node: SH Options, Next: System V Options, Prev: H8/300 Options, Up: Submodel Options
-
-SH Options
-----------
-
- These `-m' options are defined for the SH implementations:
-
-`-m1'
- Generate code for the SH1.
-
-`-m2'
- Generate code for the SH2.
-
-`-m3'
- Generate code for the SH3.
-
-`-m3e'
- Generate code for the SH3e.
-
-`-m4-nofpu'
- Generate code for the SH4 without a floating-point unit.
-
-`-m4-single-only'
- Generate code for the SH4 with a floating-point unit that only
- supports single-precision arithmetic.
-
-`-m4-single'
- Generate code for the SH4 assuming the floating-point unit is in
- single-precision mode by default.
-
-`-m4'
- Generate code for the SH4.
-
-`-mb'
- Compile code for the processor in big endian mode.
-
-`-ml'
- Compile code for the processor in little endian mode.
-
-`-mdalign'
- Align doubles at 64-bit boundaries. Note that this changes the
- calling conventions, and thus some functions from the standard C
- library will not work unless you recompile it first with
- `-mdalign'.
-
-`-mrelax'
- Shorten some address references at link time, when possible; uses
- the linker option `-relax'.
-
-`-mbigtable'
- Use 32-bit offsets in `switch' tables. The default is to use
- 16-bit offsets.
-
-`-mfmovd'
- Enable the use of the instruction `fmovd'.
-
-`-mhitachi'
- Comply with the calling conventions defined by Hitachi.
-
-`-mnomacsave'
- Mark the `MAC' register as call-clobbered, even if `-mhitachi' is
- given.
-
-`-mieee'
- Increase IEEE-compliance of floating-point code.
-
-`-misize'
- Dump instruction size and location in the assembly code.
-
-`-mpadstruct'
- This option is deprecated. It pads structures to multiple of 4
- bytes, which is incompatible with the SH ABI.
-
-`-mspace'
- Optimize for space instead of speed. Implied by `-Os'.
-
-`-mprefergot'
- When generating position-independent code, emit function calls
- using the Global Offset Table instead of the Procedure Linkage
- Table.
-
-`-musermode'
- Generate a library function call to invalidate instruction cache
- entries, after fixing up a trampoline. This library function call
- doesn't assume it can write to the whole memory address space.
- This is the default when the target is `sh-*-linux*'.
-
-\1f
-File: gcc.info, Node: System V Options, Next: TMS320C3x/C4x Options, Prev: SH Options, Up: Submodel Options
-
-Options for System V
---------------------
-
- These additional options are available on System V Release 4 for
-compatibility with other compilers on those systems:
-
-`-G'
- Create a shared object. It is recommended that `-symbolic' or
- `-shared' be used instead.
-
-`-Qy'
- Identify the versions of each tool used by the compiler, in a
- `.ident' assembler directive in the output.
-
-`-Qn'
- Refrain from adding `.ident' directives to the output file (this is
- the default).
-
-`-YP,DIRS'
- Search the directories DIRS, and no others, for libraries
- specified with `-l'.
-
-`-Ym,DIR'
- Look in the directory DIR to find the M4 preprocessor. The
- assembler uses this option.
-
+++ /dev/null
-This is doc/gcc.info, produced by makeinfo version 4.5 from
-doc/gcc.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gcc: (gcc). The GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the use of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gcc.info, Node: TMS320C3x/C4x Options, Next: V850 Options, Prev: System V Options, Up: Submodel Options
-
-TMS320C3x/C4x Options
----------------------
-
- These `-m' options are defined for TMS320C3x/C4x implementations:
-
-`-mcpu=CPU_TYPE'
- Set the instruction set, register set, and instruction scheduling
- parameters for machine type CPU_TYPE. Supported values for
- CPU_TYPE are `c30', `c31', `c32', `c40', and `c44'. The default
- is `c40' to generate code for the TMS320C40.
-
-`-mbig-memory'
-
-`-mbig'
-`-msmall-memory'
-`-msmall'
- Generates code for the big or small memory model. The small memory
- model assumed that all data fits into one 64K word page. At
- run-time the data page (DP) register must be set to point to the
- 64K page containing the .bss and .data program sections. The big
- memory model is the default and requires reloading of the DP
- register for every direct memory access.
-
-`-mbk'
-`-mno-bk'
- Allow (disallow) allocation of general integer operands into the
- block count register BK.
-
-`-mdb'
-`-mno-db'
- Enable (disable) generation of code using decrement and branch,
- DBcond(D), instructions. This is enabled by default for the C4x.
- To be on the safe side, this is disabled for the C3x, since the
- maximum iteration count on the C3x is 2^23 + 1 (but who iterates
- loops more than 2^23 times on the C3x?). Note that GCC will try
- to reverse a loop so that it can utilise the decrement and branch
- instruction, but will give up if there is more than one memory
- reference in the loop. Thus a loop where the loop counter is
- decremented can generate slightly more efficient code, in cases
- where the RPTB instruction cannot be utilised.
-
-`-mdp-isr-reload'
-`-mparanoid'
- Force the DP register to be saved on entry to an interrupt service
- routine (ISR), reloaded to point to the data section, and restored
- on exit from the ISR. This should not be required unless someone
- has violated the small memory model by modifying the DP register,
- say within an object library.
-
-`-mmpyi'
-`-mno-mpyi'
- For the C3x use the 24-bit MPYI instruction for integer multiplies
- instead of a library call to guarantee 32-bit results. Note that
- if one of the operands is a constant, then the multiplication will
- be performed using shifts and adds. If the `-mmpyi' option is not
- specified for the C3x, then squaring operations are performed
- inline instead of a library call.
-
-`-mfast-fix'
-`-mno-fast-fix'
- The C3x/C4x FIX instruction to convert a floating point value to an
- integer value chooses the nearest integer less than or equal to the
- floating point value rather than to the nearest integer. Thus if
- the floating point number is negative, the result will be
- incorrectly truncated an additional code is necessary to detect
- and correct this case. This option can be used to disable
- generation of the additional code required to correct the result.
-
-`-mrptb'
-`-mno-rptb'
- Enable (disable) generation of repeat block sequences using the
- RPTB instruction for zero overhead looping. The RPTB construct is
- only used for innermost loops that do not call functions or jump
- across the loop boundaries. There is no advantage having nested
- RPTB loops due to the overhead required to save and restore the
- RC, RS, and RE registers. This is enabled by default with `-O2'.
-
-`-mrpts=COUNT'
-`-mno-rpts'
- Enable (disable) the use of the single instruction repeat
- instruction RPTS. If a repeat block contains a single
- instruction, and the loop count can be guaranteed to be less than
- the value COUNT, GCC will emit a RPTS instruction instead of a
- RPTB. If no value is specified, then a RPTS will be emitted even
- if the loop count cannot be determined at compile time. Note that
- the repeated instruction following RPTS does not have to be
- reloaded from memory each iteration, thus freeing up the CPU buses
- for operands. However, since interrupts are blocked by this
- instruction, it is disabled by default.
-
-`-mloop-unsigned'
-`-mno-loop-unsigned'
- The maximum iteration count when using RPTS and RPTB (and DB on
- the C40) is 2^31 + 1 since these instructions test if the
- iteration count is negative to terminate the loop. If the
- iteration count is unsigned there is a possibility than the 2^31 +
- 1 maximum iteration count may be exceeded. This switch allows an
- unsigned iteration count.
-
-`-mti'
- Try to emit an assembler syntax that the TI assembler (asm30) is
- happy with. This also enforces compatibility with the API
- employed by the TI C3x C compiler. For example, long doubles are
- passed as structures rather than in floating point registers.
-
-`-mregparm'
-`-mmemparm'
- Generate code that uses registers (stack) for passing arguments to
- functions. By default, arguments are passed in registers where
- possible rather than by pushing arguments on to the stack.
-
-`-mparallel-insns'
-`-mno-parallel-insns'
- Allow the generation of parallel instructions. This is enabled by
- default with `-O2'.
-
-`-mparallel-mpy'
-`-mno-parallel-mpy'
- Allow the generation of MPY||ADD and MPY||SUB parallel
- instructions, provided `-mparallel-insns' is also specified.
- These instructions have tight register constraints which can
- pessimize the code generation of large functions.
-
-
-\1f
-File: gcc.info, Node: V850 Options, Next: ARC Options, Prev: TMS320C3x/C4x Options, Up: Submodel Options
-
-V850 Options
-------------
-
- These `-m' options are defined for V850 implementations:
-
-`-mlong-calls'
-`-mno-long-calls'
- Treat all calls as being far away (near). If calls are assumed to
- be far away, the compiler will always load the functions address
- up into a register, and call indirect through the pointer.
-
-`-mno-ep'
-`-mep'
- Do not optimize (do optimize) basic blocks that use the same index
- pointer 4 or more times to copy pointer into the `ep' register, and
- use the shorter `sld' and `sst' instructions. The `-mep' option
- is on by default if you optimize.
-
-`-mno-prolog-function'
-`-mprolog-function'
- Do not use (do use) external functions to save and restore
- registers at the prolog and epilog of a function. The external
- functions are slower, but use less code space if more than one
- function saves the same number of registers. The
- `-mprolog-function' option is on by default if you optimize.
-
-`-mspace'
- Try to make the code as small as possible. At present, this just
- turns on the `-mep' and `-mprolog-function' options.
-
-`-mtda=N'
- Put static or global variables whose size is N bytes or less into
- the tiny data area that register `ep' points to. The tiny data
- area can hold up to 256 bytes in total (128 bytes for byte
- references).
-
-`-msda=N'
- Put static or global variables whose size is N bytes or less into
- the small data area that register `gp' points to. The small data
- area can hold up to 64 kilobytes.
-
-`-mzda=N'
- Put static or global variables whose size is N bytes or less into
- the first 32 kilobytes of memory.
-
-`-mv850'
- Specify that the target processor is the V850.
-
-`-mbig-switch'
- Generate code suitable for big switch tables. Use this option
- only if the assembler/linker complain about out of range branches
- within a switch table.
-
-\1f
-File: gcc.info, Node: ARC Options, Next: NS32K Options, Prev: V850 Options, Up: Submodel Options
-
-ARC Options
------------
-
- These options are defined for ARC implementations:
-
-`-EL'
- Compile code for little endian mode. This is the default.
-
-`-EB'
- Compile code for big endian mode.
-
-`-mmangle-cpu'
- Prepend the name of the cpu to all public symbol names. In
- multiple-processor systems, there are many ARC variants with
- different instruction and register set characteristics. This flag
- prevents code compiled for one cpu to be linked with code compiled
- for another. No facility exists for handling variants that are
- "almost identical". This is an all or nothing option.
-
-`-mcpu=CPU'
- Compile code for ARC variant CPU. Which variants are supported
- depend on the configuration. All variants support `-mcpu=base',
- this is the default.
-
-`-mtext=TEXT-SECTION'
-`-mdata=DATA-SECTION'
-`-mrodata=READONLY-DATA-SECTION'
- Put functions, data, and readonly data in TEXT-SECTION,
- DATA-SECTION, and READONLY-DATA-SECTION respectively by default.
- This can be overridden with the `section' attribute. *Note
- Variable Attributes::.
-
-
-\1f
-File: gcc.info, Node: NS32K Options, Next: AVR Options, Prev: ARC Options, Up: Submodel Options
-
-NS32K Options
--------------
-
- These are the `-m' options defined for the 32000 series. The default
-values for these options depends on which style of 32000 was selected
-when the compiler was configured; the defaults for the most common
-choices are given below.
-
-`-m32032'
-`-m32032'
- Generate output for a 32032. This is the default when the
- compiler is configured for 32032 and 32016 based systems.
-
-`-m32332'
-`-m32332'
- Generate output for a 32332. This is the default when the
- compiler is configured for 32332-based systems.
-
-`-m32532'
-`-m32532'
- Generate output for a 32532. This is the default when the
- compiler is configured for 32532-based systems.
-
-`-m32081'
- Generate output containing 32081 instructions for floating point.
- This is the default for all systems.
-
-`-m32381'
- Generate output containing 32381 instructions for floating point.
- This also implies `-m32081'. The 32381 is only compatible with
- the 32332 and 32532 cpus. This is the default for the
- pc532-netbsd configuration.
-
-`-mmulti-add'
- Try and generate multiply-add floating point instructions `polyF'
- and `dotF'. This option is only available if the `-m32381' option
- is in effect. Using these instructions requires changes to
- register allocation which generally has a negative impact on
- performance. This option should only be enabled when compiling
- code particularly likely to make heavy use of multiply-add
- instructions.
-
-`-mnomulti-add'
- Do not try and generate multiply-add floating point instructions
- `polyF' and `dotF'. This is the default on all platforms.
-
-`-msoft-float'
- Generate output containing library calls for floating point.
- *Warning:* the requisite libraries may not be available.
-
-`-mnobitfield'
- Do not use the bit-field instructions. On some machines it is
- faster to use shifting and masking operations. This is the
- default for the pc532.
-
-`-mbitfield'
- Do use the bit-field instructions. This is the default for all
- platforms except the pc532.
-
-`-mrtd'
- Use a different function-calling convention, in which functions
- that take a fixed number of arguments return pop their arguments
- on return with the `ret' instruction.
-
- This calling convention is incompatible with the one normally used
- on Unix, so you cannot use it if you need to call libraries
- compiled with the Unix compiler.
-
- Also, you must provide function prototypes for all functions that
- take variable numbers of arguments (including `printf'); otherwise
- incorrect code will be generated for calls to those functions.
-
- In addition, seriously incorrect code will result if you call a
- function with too many arguments. (Normally, extra arguments are
- harmlessly ignored.)
-
- This option takes its name from the 680x0 `rtd' instruction.
-
-`-mregparam'
- Use a different function-calling convention where the first two
- arguments are passed in registers.
-
- This calling convention is incompatible with the one normally used
- on Unix, so you cannot use it if you need to call libraries
- compiled with the Unix compiler.
-
-`-mnoregparam'
- Do not pass any arguments in registers. This is the default for
- all targets.
-
-`-msb'
- It is OK to use the sb as an index register which is always loaded
- with zero. This is the default for the pc532-netbsd target.
-
-`-mnosb'
- The sb register is not available for use or has not been
- initialized to zero by the run time system. This is the default
- for all targets except the pc532-netbsd. It is also implied
- whenever `-mhimem' or `-fpic' is set.
-
-`-mhimem'
- Many ns32000 series addressing modes use displacements of up to
- 512MB. If an address is above 512MB then displacements from zero
- can not be used. This option causes code to be generated which
- can be loaded above 512MB. This may be useful for operating
- systems or ROM code.
-
-`-mnohimem'
- Assume code will be loaded in the first 512MB of virtual address
- space. This is the default for all platforms.
-
-
-\1f
-File: gcc.info, Node: AVR Options, Next: MCore Options, Prev: NS32K Options, Up: Submodel Options
-
-AVR Options
------------
-
- These options are defined for AVR implementations:
-
-`-mmcu=MCU'
- Specify ATMEL AVR instruction set or MCU type.
-
- Instruction set avr1 is for the minimal AVR core, not supported by
- the C compiler, only for assembler programs (MCU types: at90s1200,
- attiny10, attiny11, attiny12, attiny15, attiny28).
-
- Instruction set avr2 (default) is for the classic AVR core with up
- to 8K program memory space (MCU types: at90s2313, at90s2323,
- attiny22, at90s2333, at90s2343, at90s4414, at90s4433, at90s4434,
- at90s8515, at90c8534, at90s8535).
-
- Instruction set avr3 is for the classic AVR core with up to 128K
- program memory space (MCU types: atmega103, atmega603, at43usb320,
- at76c711).
-
- Instruction set avr4 is for the enhanced AVR core with up to 8K
- program memory space (MCU types: atmega8, atmega83, atmega85).
-
- Instruction set avr5 is for the enhanced AVR core with up to 128K
- program memory space (MCU types: atmega16, atmega161, atmega163,
- atmega32, atmega323, atmega64, atmega128, at43usb355, at94k).
-
-`-msize'
- Output instruction sizes to the asm file.
-
-`-minit-stack=N'
- Specify the initial stack address, which may be a symbol or
- numeric value, `__stack' is the default.
-
-`-mno-interrupts'
- Generated code is not compatible with hardware interrupts. Code
- size will be smaller.
-
-`-mcall-prologues'
- Functions prologues/epilogues expanded as call to appropriate
- subroutines. Code size will be smaller.
-
-`-mno-tablejump'
- Do not generate tablejump insns which sometimes increase code size.
-
-`-mtiny-stack'
- Change only the low 8 bits of the stack pointer.
-
-\1f
-File: gcc.info, Node: MCore Options, Next: IA-64 Options, Prev: AVR Options, Up: Submodel Options
-
-MCore Options
--------------
-
- These are the `-m' options defined for the Motorola M*Core
-processors.
-
-`-mhardlit'
-`-mhardlit'
-`-mno-hardlit'
- Inline constants into the code stream if it can be done in two
- instructions or less.
-
-`-mdiv'
-`-mdiv'
-`-mno-div'
- Use the divide instruction. (Enabled by default).
-
-`-mrelax-immediate'
-`-mrelax-immediate'
-`-mno-relax-immediate'
- Allow arbitrary sized immediates in bit operations.
-
-`-mwide-bitfields'
-`-mwide-bitfields'
-`-mno-wide-bitfields'
- Always treat bit-fields as int-sized.
-
-`-m4byte-functions'
-`-m4byte-functions'
-`-mno-4byte-functions'
- Force all functions to be aligned to a four byte boundary.
-
-`-mcallgraph-data'
-`-mcallgraph-data'
-`-mno-callgraph-data'
- Emit callgraph information.
-
-`-mslow-bytes'
-`-mslow-bytes'
-`-mno-slow-bytes'
- Prefer word access when reading byte quantities.
-
-`-mlittle-endian'
-`-mlittle-endian'
-`-mbig-endian'
- Generate code for a little endian target.
-
-`-m210'
-`-m210'
-`-m340'
- Generate code for the 210 processor.
-
-\1f
-File: gcc.info, Node: IA-64 Options, Next: D30V Options, Prev: MCore Options, Up: Submodel Options
-
-IA-64 Options
--------------
-
- These are the `-m' options defined for the Intel IA-64 architecture.
-
-`-mbig-endian'
- Generate code for a big endian target. This is the default for
- HPUX.
-
-`-mlittle-endian'
- Generate code for a little endian target. This is the default for
- AIX5 and Linux.
-
-`-mgnu-as'
-`-mno-gnu-as'
- Generate (or don't) code for the GNU assembler. This is the
- default.
-
-`-mgnu-ld'
-`-mno-gnu-ld'
- Generate (or don't) code for the GNU linker. This is the default.
-
-`-mno-pic'
- Generate code that does not use a global pointer register. The
- result is not position independent code, and violates the IA-64
- ABI.
-
-`-mvolatile-asm-stop'
-`-mno-volatile-asm-stop'
- Generate (or don't) a stop bit immediately before and after
- volatile asm statements.
-
-`-mb-step'
- Generate code that works around Itanium B step errata.
-
-`-mregister-names'
-`-mno-register-names'
- Generate (or don't) `in', `loc', and `out' register names for the
- stacked registers. This may make assembler output more readable.
-
-`-mno-sdata'
-`-msdata'
- Disable (or enable) optimizations that use the small data section.
- This may be useful for working around optimizer bugs.
-
-`-mconstant-gp'
- Generate code that uses a single constant global pointer value.
- This is useful when compiling kernel code.
-
-`-mauto-pic'
- Generate code that is self-relocatable. This implies
- `-mconstant-gp'. This is useful when compiling firmware code.
-
-`-minline-divide-min-latency'
- Generate code for inline divides using the minimum latency
- algorithm.
-
-`-minline-divide-max-throughput'
- Generate code for inline divides using the maximum throughput
- algorithm.
-
-`-mno-dwarf2-asm'
-`-mdwarf2-asm'
- Don't (or do) generate assembler code for the DWARF2 line number
- debugging info. This may be useful when not using the GNU
- assembler.
-
-`-mfixed-range=REGISTER-RANGE'
- Generate code treating the given register range as fixed registers.
- A fixed register is one that the register allocator can not use.
- This is useful when compiling kernel code. A register range is
- specified as two registers separated by a dash. Multiple register
- ranges can be specified separated by a comma.
-
-\1f
-File: gcc.info, Node: D30V Options, Next: S/390 and zSeries Options, Prev: IA-64 Options, Up: Submodel Options
-
-D30V Options
-------------
-
- These `-m' options are defined for D30V implementations:
-
-`-mextmem'
- Link the `.text', `.data', `.bss', `.strings', `.rodata',
- `.rodata1', `.data1' sections into external memory, which starts
- at location `0x80000000'.
-
-`-mextmemory'
- Same as the `-mextmem' switch.
-
-`-monchip'
- Link the `.text' section into onchip text memory, which starts at
- location `0x0'. Also link `.data', `.bss', `.strings', `.rodata',
- `.rodata1', `.data1' sections into onchip data memory, which
- starts at location `0x20000000'.
-
-`-mno-asm-optimize'
-`-masm-optimize'
- Disable (enable) passing `-O' to the assembler when optimizing.
- The assembler uses the `-O' option to automatically parallelize
- adjacent short instructions where possible.
-
-`-mbranch-cost=N'
- Increase the internal costs of branches to N. Higher costs means
- that the compiler will issue more instructions to avoid doing a
- branch. The default is 2.
-
-`-mcond-exec=N'
- Specify the maximum number of conditionally executed instructions
- that replace a branch. The default is 4.
-
-\1f
-File: gcc.info, Node: S/390 and zSeries Options, Next: CRIS Options, Prev: D30V Options, Up: Submodel Options
-
-S/390 and zSeries Options
--------------------------
-
- These are the `-m' options defined for the S/390 and zSeries
-architecture.
-
-`-mhard-float'
-`-msoft-float'
- Use (do not use) the hardware floating-point instructions and
- registers for floating-point operations. When `-msoft-float' is
- specified, functions in `libgcc.a' will be used to perform
- floating-point operations. When `-mhard-float' is specified, the
- compiler generates IEEE floating-point instructions. This is the
- default.
-
-`-mbackchain'
-`-mno-backchain'
- Generate (or do not generate) code which maintains an explicit
- backchain within the stack frame that points to the caller's frame.
- This is currently needed to allow debugging. The default is to
- generate the backchain.
-
-`-msmall-exec'
-`-mno-small-exec'
- Generate (or do not generate) code using the `bras' instruction to
- do subroutine calls. This only works reliably if the total
- executable size does not exceed 64k. The default is to use the
- `basr' instruction instead, which does not have this limitation.
-
-`-m64'
-`-m31'
- When `-m31' is specified, generate code compliant to the Linux for
- S/390 ABI. When `-m64' is specified, generate code compliant to
- the Linux for zSeries ABI. This allows GCC in particular to
- generate 64-bit instructions. For the `s390' targets, the default
- is `-m31', while the `s390x' targets default to `-m64'.
-
-`-mmvcle'
-`-mno-mvcle'
- Generate (or do not generate) code using the `mvcle' instruction
- to perform block moves. When `-mno-mvcle' is specifed, use a
- `mvc' loop instead. This is the default.
-
-`-mdebug'
-`-mno-debug'
- Print (or do not print) additional debug information when
- compiling. The default is to not print debug information.
-
-
-\1f
-File: gcc.info, Node: CRIS Options, Next: MMIX Options, Prev: S/390 and zSeries Options, Up: Submodel Options
-
-CRIS Options
-------------
-
- These options are defined specifically for the CRIS ports.
-
-`-march=ARCHITECTURE-TYPE'
-`-mcpu=ARCHITECTURE-TYPE'
- Generate code for the specified architecture. The choices for
- ARCHITECTURE-TYPE are `v3', `v8' and `v10' for respectively
- ETRAX 4, ETRAX 100, and ETRAX 100 LX. Default is `v0' except for
- cris-axis-linux-gnu, where the default is `v10'.
-
-`-mtune=ARCHITECTURE-TYPE'
- Tune to ARCHITECTURE-TYPE everything applicable about the generated
- code, except for the ABI and the set of available instructions.
- The choices for ARCHITECTURE-TYPE are the same as for
- `-march=ARCHITECTURE-TYPE'.
-
-`-mmax-stack-frame=N'
- Warn when the stack frame of a function exceeds N bytes.
-
-`-melinux-stacksize=N'
- Only available with the `cris-axis-aout' target. Arranges for
- indications in the program to the kernel loader that the stack of
- the program should be set to N bytes.
-
-`-metrax4'
-`-metrax100'
- The options `-metrax4' and `-metrax100' are synonyms for
- `-march=v3' and `-march=v8' respectively.
-
-`-mpdebug'
- Enable CRIS-specific verbose debug-related information in the
- assembly code. This option also has the effect to turn off the
- `#NO_APP' formatted-code indicator to the assembler at the
- beginning of the assembly file.
-
-`-mcc-init'
- Do not use condition-code results from previous instruction;
- always emit compare and test instructions before use of condition
- codes.
-
-`-mno-side-effects'
- Do not emit instructions with side-effects in addressing modes
- other than post-increment.
-
-`-mstack-align'
-`-mno-stack-align'
-`-mdata-align'
-`-mno-data-align'
-`-mconst-align'
-`-mno-const-align'
- These options (no-options) arranges (eliminate arrangements) for
- the stack-frame, individual data and constants to be aligned for
- the maximum single data access size for the chosen CPU model. The
- default is to arrange for 32-bit alignment. ABI details such as
- structure layout are not affected by these options.
-
-`-m32-bit'
-`-m16-bit'
-`-m8-bit'
- Similar to the stack- data- and const-align options above, these
- options arrange for stack-frame, writable data and constants to
- all be 32-bit, 16-bit or 8-bit aligned. The default is 32-bit
- alignment.
-
-`-mno-prologue-epilogue'
-`-mprologue-epilogue'
- With `-mno-prologue-epilogue', the normal function prologue and
- epilogue that sets up the stack-frame are omitted and no return
- instructions or return sequences are generated in the code. Use
- this option only together with visual inspection of the compiled
- code: no warnings or errors are generated when call-saved
- registers must be saved, or storage for local variable needs to be
- allocated.
-
-`-mno-gotplt'
-`-mgotplt'
- With `-fpic' and `-fPIC', don't generate (do generate) instruction
- sequences that load addresses for functions from the PLT part of
- the GOT rather than (traditional on other architectures) calls to
- the PLT. The default is `-mgotplt'.
-
-`-maout'
- Legacy no-op option only recognized with the cris-axis-aout target.
-
-`-melf'
- Legacy no-op option only recognized with the cris-axis-elf and
- cris-axis-linux-gnu targets.
-
-`-melinux'
- Only recognized with the cris-axis-aout target, where it selects a
- GNU/linux-like multilib, include files and instruction set for
- `-march=v8'.
-
-`-mlinux'
- Legacy no-op option only recognized with the cris-axis-linux-gnu
- target.
-
-`-sim'
- This option, recognized for the cris-axis-aout and cris-axis-elf
- arranges to link with input-output functions from a simulator
- library. Code, initialized data and zero-initialized data are
- allocated consecutively.
-
-`-sim2'
- Like `-sim', but pass linker options to locate initialized data at
- 0x40000000 and zero-initialized data at 0x80000000.
-
-\1f
-File: gcc.info, Node: MMIX Options, Next: PDP-11 Options, Prev: CRIS Options, Up: Submodel Options
-
-MMIX Options
-------------
-
- These options are defined for the MMIX:
-
-`-mlibfuncs'
-`-mno-libfuncs'
- Specify that intrinsic library functions are being compiled,
- passing all values in registers, no matter the size.
-
-`-mepsilon'
-`-mno-epsilon'
- Generate floating-point comparison instructions that compare with
- respect to the `rE' epsilon register.
-
-`-mabi=mmixware'
-`-mabi=gnu'
- Generate code that passes function parameters and return values
- that (in the called function) are seen as registers `$0' and up,
- as opposed to the GNU ABI which uses global registers `$231' and
- up.
-
-`-mzero-extend'
-`-mno-zero-extend'
- When reading data from memory in sizes shorter than 64 bits, use
- (do not use) zero-extending load instructions by default, rather
- than sign-extending ones.
-
-`-mknuthdiv'
-`-mno-knuthdiv'
- Make the result of a division yielding a remainder have the same
- sign as the divisor. With the default, `-mno-knuthdiv', the sign
- of the remainder follows the sign of the dividend. Both methods
- are arithmetically valid, the latter being almost exclusively used.
-
-`-mtoplevel-symbols'
-`-mno-toplevel-symbols'
- Prepend (do not prepend) a `:' to all global symbols, so the
- assembly code can be used with the `PREFIX' assembly directive.
-
-`-melf'
- Generate an executable in the ELF format, rather than the default
- `mmo' format used by the `mmix' simulator.
-
-`-mbranch-predict'
-`-mno-branch-predict'
- Use (do not use) the probable-branch instructions, when static
- branch prediction indicates a probable branch.
-
-`-mbase-addresses'
-`-mno-base-addresses'
- Generate (do not generate) code that uses _base addresses_. Using
- a base address automatically generates a request (handled by the
- assembler and the linker) for a constant to be set up in a global
- register. The register is used for one or more base address
- requests within the range 0 to 255 from the value held in the
- register. The generally leads to short and fast code, but the
- number of different data items that can be addressed is limited.
- This means that a program that uses lots of static data may
- require `-mno-base-addresses'.
-
-\1f
-File: gcc.info, Node: PDP-11 Options, Next: Xstormy16 Options, Prev: MMIX Options, Up: Submodel Options
-
-PDP-11 Options
---------------
-
- These options are defined for the PDP-11:
-
-`-mfpu'
- Use hardware FPP floating point. This is the default. (FIS
- floating point on the PDP-11/40 is not supported.)
-
-`-msoft-float'
- Do not use hardware floating point.
-
-`-mac0'
- Return floating-point results in ac0 (fr0 in Unix assembler
- syntax).
-
-`-mno-ac0'
- Return floating-point results in memory. This is the default.
-
-`-m40'
- Generate code for a PDP-11/40.
-
-`-m45'
- Generate code for a PDP-11/45. This is the default.
-
-`-m10'
- Generate code for a PDP-11/10.
-
-`-mbcopy-builtin'
- Use inline `movstrhi' patterns for copying memory. This is the
- default.
-
-`-mbcopy'
- Do not use inline `movstrhi' patterns for copying memory.
-
-`-mint16'
-`-mno-int32'
- Use 16-bit `int'. This is the default.
-
-`-mint32'
-`-mno-int16'
- Use 32-bit `int'.
-
-`-mfloat64'
-`-mno-float32'
- Use 64-bit `float'. This is the default.
-
-`-mfloat32'
-
-`-mno-float64'
- Use 32-bit `float'.
-
-`-mabshi'
- Use `abshi2' pattern. This is the default.
-
-`-mno-abshi'
- Do not use `abshi2' pattern.
-
-`-mbranch-expensive'
- Pretend that branches are expensive. This is for experimenting
- with code generation only.
-
-`-mbranch-cheap'
- Do not pretend that branches are expensive. This is the default.
-
-`-msplit'
- Generate code for a system with split I&D.
-
-`-mno-split'
- Generate code for a system without split I&D. This is the default.
-
-`-munix-asm'
- Use Unix assembler syntax. This is the default when configured for
- `pdp11-*-bsd'.
-
-`-mdec-asm'
- Use DEC assembler syntax. This is the default when configured for
- any PDP-11 target other than `pdp11-*-bsd'.
-
-\1f
-File: gcc.info, Node: Xstormy16 Options, Next: Xtensa Options, Prev: PDP-11 Options, Up: Submodel Options
-
-Xstormy16 Options
------------------
-
- These options are defined for Xstormy16:
-
-`-msim'
- Choose startup files and linker script suitable for the simulator.
-
-\1f
-File: gcc.info, Node: Xtensa Options, Prev: Xstormy16 Options, Up: Submodel Options
-
-Xtensa Options
---------------
-
- The Xtensa architecture is designed to support many different
-configurations. The compiler's default options can be set to match a
-particular Xtensa configuration by copying a configuration file into the
-GCC sources when building GCC. The options below may be used to
-override the default options.
-
-`-mbig-endian'
-`-mlittle-endian'
- Specify big-endian or little-endian byte ordering for the target
- Xtensa processor.
-
-`-mdensity'
-`-mno-density'
- Enable or disable use of the optional Xtensa code density
- instructions.
-
-`-mmac16'
-`-mno-mac16'
- Enable or disable use of the Xtensa MAC16 option. When enabled,
- GCC will generate MAC16 instructions from standard C code, with the
- limitation that it will use neither the MR register file nor any
- instruction that operates on the MR registers. When this option is
- disabled, GCC will translate 16-bit multiply/accumulate operations
- to a combination of core instructions and library calls, depending
- on whether any other multiplier options are enabled.
-
-`-mmul16'
-`-mno-mul16'
- Enable or disable use of the 16-bit integer multiplier option.
- When enabled, the compiler will generate 16-bit multiply
- instructions for multiplications of 16 bits or smaller in standard
- C code. When this option is disabled, the compiler will either
- use 32-bit multiply or MAC16 instructions if they are available or
- generate library calls to perform the multiply operations using
- shifts and adds.
-
-`-mmul32'
-`-mno-mul32'
- Enable or disable use of the 32-bit integer multiplier option.
- When enabled, the compiler will generate 32-bit multiply
- instructions for multiplications of 32 bits or smaller in standard
- C code. When this option is disabled, the compiler will generate
- library calls to perform the multiply operations using either
- shifts and adds or 16-bit multiply instructions if they are
- available.
-
-`-mnsa'
-`-mno-nsa'
- Enable or disable use of the optional normalization shift amount
- (`NSA') instructions to implement the built-in `ffs' function.
-
-`-mminmax'
-`-mno-minmax'
- Enable or disable use of the optional minimum and maximum value
- instructions.
-
-`-msext'
-`-mno-sext'
- Enable or disable use of the optional sign extend (`SEXT')
- instruction.
-
-`-mbooleans'
-`-mno-booleans'
- Enable or disable support for the boolean register file used by
- Xtensa coprocessors. This is not typically useful by itself but
- may be required for other options that make use of the boolean
- registers (e.g., the floating-point option).
-
-`-mhard-float'
-`-msoft-float'
- Enable or disable use of the floating-point option. When enabled,
- GCC generates floating-point instructions for 32-bit `float'
- operations. When this option is disabled, GCC generates library
- calls to emulate 32-bit floating-point operations using integer
- instructions. Regardless of this option, 64-bit `double'
- operations are always emulated with calls to library functions.
-
-`-mfused-madd'
-`-mno-fused-madd'
- Enable or disable use of fused multiply/add and multiply/subtract
- instructions in the floating-point option. This has no effect if
- the floating-point option is not also enabled. Disabling fused
- multiply/add and multiply/subtract instructions forces the
- compiler to use separate instructions for the multiply and
- add/subtract operations. This may be desirable in some cases
- where strict IEEE 754-compliant results are required: the fused
- multiply add/subtract instructions do not round the intermediate
- result, thereby producing results with _more_ bits of precision
- than specified by the IEEE standard. Disabling fused multiply
- add/subtract instructions also ensures that the program output is
- not sensitive to the compiler's ability to combine multiply and
- add/subtract operations.
-
-`-mserialize-volatile'
-`-mno-serialize-volatile'
- When this option is enabled, GCC inserts `MEMW' instructions before
- `volatile' memory references to guarantee sequential consistency.
- The default is `-mserialize-volatile'. Use
- `-mno-serialize-volatile' to omit the `MEMW' instructions.
-
-`-mtext-section-literals'
-`-mno-text-section-literals'
- Control the treatment of literal pools. The default is
- `-mno-text-section-literals', which places literals in a separate
- section in the output file. This allows the literal pool to be
- placed in a data RAM/ROM, and it also allows the linker to combine
- literal pools from separate object files to remove redundant
- literals and improve code size. With `-mtext-section-literals',
- the literals are interspersed in the text section in order to keep
- them as close as possible to their references. This may be
- necessary for large assembly files.
-
-`-mtarget-align'
-`-mno-target-align'
- When this option is enabled, GCC instructs the assembler to
- automatically align instructions to reduce branch penalties at the
- expense of some code density. The assembler attempts to widen
- density instructions to align branch targets and the instructions
- following call instructions. If there are not enough preceding
- safe density instructions to align a target, no widening will be
- performed. The default is `-mtarget-align'. These options do not
- affect the treatment of auto-aligned instructions like `LOOP',
- which the assembler will always align, either by widening density
- instructions or by inserting no-op instructions.
-
-`-mlongcalls'
-`-mno-longcalls'
- When this option is enabled, GCC instructs the assembler to
- translate direct calls to indirect calls unless it can determine
- that the target of a direct call is in the range allowed by the
- call instruction. This translation typically occurs for calls to
- functions in other source files. Specifically, the assembler
- translates a direct `CALL' instruction into an `L32R' followed by
- a `CALLX' instruction. The default is `-mno-longcalls'. This
- option should be used in programs where the call target can
- potentially be out of range. This option is implemented in the
- assembler, not the compiler, so the assembly code generated by GCC
- will still show direct call instructions--look at the disassembled
- object code to see the actual instructions. Note that the
- assembler will use an indirect call for every cross-file call, not
- just those that really will be out of range.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
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-gccint.info-6: 222790
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-gccint.info-15: 587199
-gccint.info-16: 635215
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-gccint.info-18: 723825
-gccint.info-19: 768901
-gccint.info-20: 816265
-gccint.info-21: 865703
-gccint.info-22: 907964
-gccint.info-23: 934646
-\1f
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-Node: Test Suites\7f51428
-Node: Test Idioms\7f51928
-Node: C Tests\7f54796
-Node: libgcj Tests\7f57542
-Node: Passes\7f58454
-Node: Trees\7f81772
-Node: Deficiencies\7f84501
-Node: Tree overview\7f84734
-Node: Macros and Functions\7f88872
-Node: Identifiers\7f89009
-Node: Containers\7f90529
-Node: Types\7f91676
-Node: Scopes\7f104401
-Node: Namespaces\7f105160
-Node: Classes\7f107968
-Node: Declarations\7f112570
-Node: Functions\7f118629
-Node: Function Basics\7f121162
-Node: Function Bodies\7f127912
-Node: Attributes\7f141818
-Node: Expression trees\7f143054
-Node: RTL\7f167446
-Node: RTL Objects\7f169480
-Node: RTL Classes\7f173371
-Node: Accessors\7f177932
-Node: Flags\7f180315
-Node: Machine Modes\7f195220
-Node: Constants\7f203953
-Node: Regs and Memory\7f209919
-Node: Arithmetic\7f222790
-Node: Comparisons\7f229449
-Node: Bit-Fields\7f233572
-Node: Vector Operations\7f234993
-Node: Conversions\7f236771
-Node: RTL Declarations\7f240081
-Node: Side Effects\7f240893
-Node: Incdec\7f256686
-Node: Assembler\7f260242
-Node: Insns\7f261767
-Node: Calls\7f286565
-Node: Sharing\7f289162
-Node: Reading RTL\7f292266
-Node: Machine Desc\7f293252
-Node: Overview\7f295531
-Node: Patterns\7f297573
-Node: Example\7f301006
-Node: RTL Template\7f302440
-Node: Output Template\7f314908
-Node: Output Statement\7f318893
-Node: Constraints\7f322867
-Node: Simple Constraints\7f323801
-Node: Multi-Alternative\7f336165
-Node: Class Preferences\7f339003
-Node: Modifiers\7f339886
-Node: Machine Constraints\7f343547
-Node: Standard Names\7f360144
-Ref: prologue instruction pattern\7f399527
-Ref: epilogue instruction pattern\7f400020
-Node: Pattern Ordering\7f402749
-Node: Dependent Patterns\7f403979
-Node: Jump Patterns\7f406797
-Node: Looping Patterns\7f412547
-Node: Insn Canonicalizations\7f417153
-Node: Expander Definitions\7f420654
-Node: Insn Splitting\7f428789
-Node: Including Patterns\7f438407
-Node: Peephole Definitions\7f440185
-Node: define_peephole\7f441435
-Node: define_peephole2\7f447784
-Node: Insn Attributes\7f450848
-Node: Defining Attributes\7f451934
-Node: Expressions\7f453949
-Node: Tagging Insns\7f460541
-Node: Attr Example\7f464906
-Node: Insn Lengths\7f467285
-Node: Constant Attributes\7f470547
-Node: Delay Slots\7f471710
-Node: Function Units\7f474924
-Node: Conditional Execution\7f480597
-Node: Constant Definitions\7f483456
-Node: Target Macros\7f485037
-Node: Target Structure\7f487726
-Node: Driver\7f489017
-Node: Run-time Target\7f508350
-Node: Per-Function Data\7f515840
-Node: Storage Layout\7f519105
-Node: Type Layout\7f538134
-Node: Escape Sequences\7f548486
-Node: Registers\7f549401
-Node: Register Basics\7f550324
-Node: Allocation Order\7f555929
-Node: Values in Registers\7f557345
-Node: Leaf Functions\7f562180
-Node: Stack Registers\7f564969
-Node: Register Classes\7f565769
-Node: Stack and Calling\7f586703
-Node: Frame Layout\7f587199
-Node: Exception Handling\7f594064
-Node: Stack Checking\7f598566
-Node: Frame Registers\7f602123
-Node: Elimination\7f607575
-Node: Stack Arguments\7f611548
-Node: Register Arguments\7f619104
-Node: Scalar Return\7f630974
-Node: Aggregate Return\7f635215
-Node: Caller Saves\7f638932
-Node: Function Entry\7f640472
-Node: Profiling\7f652561
-Node: Tail Calls\7f654894
-Node: Varargs\7f655485
-Node: Trampolines\7f663163
-Node: Library Calls\7f670398
-Node: Addressing Modes\7f675920
-Node: Condition Code\7f687197
-Node: Costs\7f694524
-Node: Scheduling\7f706283
-Node: Sections\7f711799
-Node: PIC\7f719954
-Node: Assembler Format\7f722755
-Node: File Framework\7f723825
-Node: Data Output\7f728685
-Node: Uninitialized Data\7f736558
-Node: Label Output\7f741958
-Node: Initialization\7f756751
-Node: Macros for Initialization\7f762732
-Node: Instruction Output\7f768901
-Node: Dispatch Tables\7f777941
-Node: Exception Region Output\7f780496
-Node: Alignment Output\7f783850
-Node: Debugging Info\7f787722
-Node: All Debuggers\7f788386
-Node: DBX Options\7f791269
-Node: DBX Hooks\7f796644
-Node: File Names and DBX\7f800468
-Node: SDB and DWARF\7f802444
-Node: VMS Debug\7f805885
-Node: Cross-compilation\7f806433
-Node: Mode Switching\7f813012
-Node: Target Attributes\7f816265
-Node: Misc\7f820102
-Node: Host Config\7f848584
-Node: Fragments\7f854620
-Node: Target Fragment\7f855763
-Node: Host Fragment\7f860258
-Node: Collect2\7f861695
-Node: Header Dirs\7f864252
-Node: Funding\7f865703
-Node: GNU Project\7f868209
-Node: Copying\7f868863
-Node: GNU Free Documentation License\7f888077
-Node: Contributors\7f907964
-Node: Option Index\7f932895
-Node: Index\7f934646
-\1f
-End Tag Table
-This is doc/gccint.info, produced by makeinfo version 4.5 from
+This is doc/gccint.info, produced by makeinfo version 4.11 from
doc/gccint.texi.
INFO-DIR-SECTION Programming
Introduction
************
- This manual documents the internals of the GNU compilers, including
-how to port them to new targets and some information about how to write
+This manual documents the internals of the GNU compilers, including how
+to port them to new targets and some information about how to write
front ends for new languages. It corresponds to GCC version 3.2.3.
The use of the GNU compilers is documented in a separate manual. *Note
Introduction: (gcc)Top.
\1f
File: gccint.info, Node: Contributing, Next: Portability, Prev: Top, Up: Top
-Contributing to GCC Development
-*******************************
+1 Contributing to GCC Development
+*********************************
- If you would like to help pretest GCC releases to assure they work
-well, our current development sources are available by CVS (see
+If you would like to help pretest GCC releases to assure they work well,
+our current development sources are available by CVS (see
`http://gcc.gnu.org/cvs.html'). Source and binary snapshots are also
available for FTP; see `http://gcc.gnu.org/snapshots.html'.
\1f
File: gccint.info, Node: Portability, Next: Interface, Prev: Contributing, Up: Top
-GCC and Portability
-*******************
+2 GCC and Portability
+*********************
- The main goal of GCC was to make a good, fast compiler for machines
-in the class that the GNU system aims to run on: 32-bit machines that
+The main goal of GCC was to make a good, fast compiler for machines in
+the class that the GNU system aims to run on: 32-bit machines that
address 8-bit bytes and have several general registers. Elegance,
theoretical power and simplicity are only secondary.
\1f
File: gccint.info, Node: Interface, Next: Languages, Prev: Portability, Up: Top
-Interfacing to GCC Output
-*************************
+3 Interfacing to GCC Output
+***************************
- GCC is normally configured to use the same function calling
-convention normally in use on the target system. This is done with the
+GCC is normally configured to use the same function calling convention
+normally in use on the target system. This is done with the
machine-description macros described (*note Target Macros::).
However, returning of structure and union values is done differently
\1f
File: gccint.info, Node: Languages, Next: Source Tree, Prev: Interface, Up: Top
-Language Front Ends in GCC
-**************************
+4 Language Front Ends in GCC
+****************************
- The interface to front ends for languages in GCC, and in particular
-the `tree' structure (*note Trees::), was initially designed for C, and
+The interface to front ends for languages in GCC, and in particular the
+`tree' structure (*note Trees::), was initially designed for C, and
many aspects of it are still somewhat biased towards C and C-like
languages. It is, however, reasonably well suited to other procedural
languages, and front ends for many such languages have been written for
\1f
File: gccint.info, Node: Source Tree, Next: Passes, Prev: Languages, Up: Top
-Source Tree Structure and Build System
-**************************************
+5 Source Tree Structure and Build System
+****************************************
- This chapter describes the structure of the GCC source tree, and how
+This chapter describes the structure of the GCC source tree, and how
GCC is built. The user documentation for building and installing GCC
is in a separate manual (`http://gcc.gnu.org/install/'), with which it
is presumed that you are familiar.
\1f
File: gccint.info, Node: Configure Terms, Next: Top Level, Up: Source Tree
-Configure Terms and History
-===========================
+5.1 Configure Terms and History
+===============================
- The configure and build process has a long and colorful history, and
-can be confusing to anyone who doesn't know why things are the way they
-are. While there are other documents which describe the configuration
-process in detail, here are a few things that everyone working on GCC
-should know.
+The configure and build process has a long and colorful history, and can
+be confusing to anyone who doesn't know why things are the way they are.
+While there are other documents which describe the configuration process
+in detail, here are a few things that everyone working on GCC should
+know.
There are three system names that the build knows about: the machine
you are building on ("build"), the machine that you are building for
\1f
File: gccint.info, Node: Top Level, Next: gcc Directory, Prev: Configure Terms, Up: Source Tree
-Top Level Source Directory
-==========================
+5.2 Top Level Source Directory
+==============================
- The top level source directory in a GCC distribution contains several
+The top level source directory in a GCC distribution contains several
files and directories that are shared with other software distributions
such as that of GNU Binutils. It also contains several subdirectories
that contain parts of GCC and its runtime libraries:
\1f
File: gccint.info, Node: gcc Directory, Next: Test Suites, Prev: Top Level, Up: Source Tree
-The `gcc' Subdirectory
-======================
+5.3 The `gcc' Subdirectory
+==========================
- The `gcc' directory contains many files that are part of the C
-sources of GCC, other files used as part of the configuration and build
+The `gcc' directory contains many files that are part of the C sources
+of GCC, other files used as part of the configuration and build
process, and subdirectories including documentation and a test suite.
The files that are sources of GCC are documented in a separate chapter.
*Note Passes and Files of the Compiler: Passes.
\1f
File: gccint.info, Node: Subdirectories, Next: Configuration, Up: gcc Directory
-Subdirectories of `gcc'
------------------------
+5.3.1 Subdirectories of `gcc'
+-----------------------------
- The `gcc' directory contains the following subdirectories:
+The `gcc' directory contains the following subdirectories:
`LANGUAGE'
Subdirectories for various languages. Directories containing a
\1f
File: gccint.info, Node: Configuration, Next: Build, Prev: Subdirectories, Up: gcc Directory
-Configuration in the `gcc' Directory
-------------------------------------
+5.3.2 Configuration in the `gcc' Directory
+------------------------------------------
- The `gcc' directory is configured with an Autoconf-generated script
+The `gcc' directory is configured with an Autoconf-generated script
`configure'. The `configure' script is generated from `configure.in'
and `aclocal.m4'. From the files `configure.in' and `acconfig.h',
Autoheader generates the file `config.in'. The file `cstamp-h.in' is
\1f
File: gccint.info, Node: Config Fragments, Next: System Config, Up: Configuration
-Scripts Used by `configure'
-...........................
+5.3.2.1 Scripts Used by `configure'
+...................................
- `configure' uses some other scripts to help in its work:
+`configure' uses some other scripts to help in its work:
* The standard GNU `config.sub' and `config.guess' files, kept in
the top level directory, are used. FIXME: when is the
\1f
File: gccint.info, Node: System Config, Next: Configuration Files, Prev: Config Fragments, Up: Configuration
-The `config.gcc' File
-.....................
+5.3.2.2 The `config.gcc' File
+.............................
- FIXME: document the contents of this file, and what variables should
-be set to control build, host and target configuration.
+FIXME: document the contents of this file, and what variables should be
+set to control build, host and target configuration.
\1f
File: gccint.info, Node: Configuration Files, Prev: System Config, Up: Configuration
-Files Created by `configure'
-............................
+5.3.2.3 Files Created by `configure'
+....................................
- Here we spell out what files will be set up by `configure' in the
-`gcc' directory. Some other files are created as temporary files in
-the configuration process, and are not used in the subsequent build;
-these are not documented.
+Here we spell out what files will be set up by `configure' in the `gcc'
+directory. Some other files are created as temporary files in the
+configuration process, and are not used in the subsequent build; these
+are not documented.
* `Makefile' is constructed from `Makefile.in', together with the
host and target fragments (*note Makefile Fragments: Fragments.)
\1f
File: gccint.info, Node: Build, Next: Makefile, Prev: Configuration, Up: gcc Directory
-Build System in the `gcc' Directory
------------------------------------
+5.3.3 Build System in the `gcc' Directory
+-----------------------------------------
- FIXME: describe the build system, including what is built in what
+FIXME: describe the build system, including what is built in what
stages. Also list the various source files that are used in the build
process but aren't source files of GCC itself and so aren't documented
below (*note Passes::).
\1f
File: gccint.info, Node: Makefile, Next: Library Files, Prev: Build, Up: gcc Directory
-Makefile Targets
-----------------
+5.3.4 Makefile Targets
+----------------------
`all'
This is the default target. Depending on what your
\1f
File: gccint.info, Node: Library Files, Next: Headers, Prev: Makefile, Up: gcc Directory
-Library Source Files and Headers under the `gcc' Directory
-----------------------------------------------------------
+5.3.5 Library Source Files and Headers under the `gcc' Directory
+----------------------------------------------------------------
- FIXME: list here, with explanation, all the C source files and
-headers under the `gcc' directory that aren't built into the GCC
-executable but rather are part of runtime libraries and object files,
-such as `crtstuff.c' and `unwind-dw2.c'. *Note Headers Installed by
-GCC: Headers, for more information about the `ginclude' directory.
+FIXME: list here, with explanation, all the C source files and headers
+under the `gcc' directory that aren't built into the GCC executable but
+rather are part of runtime libraries and object files, such as
+`crtstuff.c' and `unwind-dw2.c'. *Note Headers Installed by GCC:
+Headers, for more information about the `ginclude' directory.
\1f
File: gccint.info, Node: Headers, Next: Documentation, Prev: Library Files, Up: gcc Directory
-Headers Installed by GCC
-------------------------
+5.3.6 Headers Installed by GCC
+------------------------------
- In general, GCC expects the system C library to provide most of the
+In general, GCC expects the system C library to provide most of the
headers to be used with it. However, GCC will fix those headers if
necessary to make them work with GCC, and will install some headers
required of freestanding implementations. These headers are installed
\1f
File: gccint.info, Node: Documentation, Next: Front End, Prev: Headers, Up: gcc Directory
-Building Documentation
-----------------------
+5.3.7 Building Documentation
+----------------------------
- The main GCC documentation is in the form of manuals in Texinfo
-format. These are installed in Info format, and DVI versions may be
-generated by `make dvi'. In addition, some man pages are generated
-from the Texinfo manuals, there are some other text files with
-miscellaneous documentation, and runtime libraries have their own
-documentation outside the `gcc' directory. FIXME: document the
-documentation for runtime libraries somewhere.
+The main GCC documentation is in the form of manuals in Texinfo format.
+These are installed in Info format, and DVI versions may be generated
+by `make dvi'. In addition, some man pages are generated from the
+Texinfo manuals, there are some other text files with miscellaneous
+documentation, and runtime libraries have their own documentation
+outside the `gcc' directory. FIXME: document the documentation for
+runtime libraries somewhere.
* Menu:
\1f
File: gccint.info, Node: Texinfo Manuals, Next: Man Page Generation, Up: Documentation
-Texinfo Manuals
-...............
+5.3.7.1 Texinfo Manuals
+.......................
- The manuals for GCC as a whole, and the C and C++ front ends, are in
+The manuals for GCC as a whole, and the C and C++ front ends, are in
files `doc/*.texi'. Other front ends have their own manuals in files
`LANGUAGE/*.texi'. Common files `doc/include/*.texi' are provided
which may be included in multiple manuals; the following files are in
\1f
File: gccint.info, Node: Man Page Generation, Next: Miscellaneous Docs, Prev: Texinfo Manuals, Up: Documentation
-Man Page Generation
-...................
+5.3.7.2 Man Page Generation
+...........................
- Because of user demand, in addition to full Texinfo manuals, man
-pages are provided which contain extracts from those manuals. These man
+Because of user demand, in addition to full Texinfo manuals, man pages
+are provided which contain extracts from those manuals. These man
pages are generated from the Texinfo manuals using
`contrib/texi2pod.pl' and `pod2man'. (The man page for `g++',
`cp/g++.1', just contains a `.so' reference to `gcc.1', but all the
\1f
File: gccint.info, Node: Miscellaneous Docs, Prev: Man Page Generation, Up: Documentation
-Miscellaneous Documentation
-...........................
+5.3.7.3 Miscellaneous Documentation
+...................................
- In addition to the formal documentation that is installed by GCC,
-there are several other text files with miscellaneous documentation:
+In addition to the formal documentation that is installed by GCC, there
+are several other text files with miscellaneous documentation:
`ABOUT-GCC-NLS'
Notes on GCC's Native Language Support. FIXME: this should be
\1f
File: gccint.info, Node: Front End, Next: Back End, Prev: Documentation, Up: gcc Directory
-Anatomy of a Language Front End
--------------------------------
+5.3.8 Anatomy of a Language Front End
+-------------------------------------
- A front end for a language in GCC has the following parts:
+A front end for a language in GCC has the following parts:
* A directory `LANGUAGE' under `gcc' containing source files for
that front end. *Note The Front End `LANGUAGE' Directory: Front
\1f
File: gccint.info, Node: Front End Directory, Next: Front End Config, Up: Front End
-The Front End `LANGUAGE' Directory
-..................................
+5.3.8.1 The Front End `LANGUAGE' Directory
+..........................................
- A front end `LANGUAGE' directory contains the source files of that
+A front end `LANGUAGE' directory contains the source files of that
front end (but not of any runtime libraries, which should be outside
the `gcc' directory). This includes documentation, and possibly some
subsidiary programs build alongside the front end. Certain files are
\1f
File: gccint.info, Node: Front End Config, Prev: Front End Directory, Up: Front End
-The Front End `config-lang.in' File
-...................................
+5.3.8.2 The Front End `config-lang.in' File
+...........................................
- Each language subdirectory contains a `config-lang.in' file. This
-file is a shell script that may define some variables describing the
+Each language subdirectory contains a `config-lang.in' file. This file
+is a shell script that may define some variables describing the
language:
`language'
`LANGUAGE/Makefile.in', but this is deprecated, building
everything from the single `gcc/Makefile' is preferred.
+\1f
+File: gccint.info, Node: Back End, Prev: Front End, Up: gcc Directory
+
+5.3.9 Anatomy of a Target Back End
+----------------------------------
+
+A back end for a target architecture in GCC has the following parts:
+
+ * A directory `MACHINE' under `gcc/config', containing a machine
+ description `MACHINE.md' file (*note Machine Descriptions: Machine
+ Desc.), header files `MACHINE.h' and `MACHINE-protos.h' and a
+ source file `MACHINE.c' (*note Target Description Macros and
+ Functions: Target Macros.), possibly a target Makefile fragment
+ `t-MACHINE' (*note The Target Makefile Fragment: Target
+ Fragment.), and maybe some other files. The names of these files
+ may be changed from the defaults given by explicit specifications
+ in `config.gcc'.
+
+ * Entries in `config.gcc' (*note The `config.gcc' File: System
+ Config.) for the systems with this target architecture.
+
+ * Documentation in `gcc/doc/invoke.texi' for any command-line
+ options supported by this target (*note Run-time Target
+ Specification: Run-time Target.). This means both entries in the
+ summary table of options and details of the individual options.
+
+ * Documentation in `gcc/doc/extend.texi' for any target-specific
+ attributes supported (*note Defining target-specific uses of
+ `__attribute__': Target Attributes.), including where the same
+ attribute is already supported on some targets, which are
+ enumerated in the manual.
+
+ * Documentation in `gcc/doc/extend.texi' for any target-specific
+ pragmas supported.
+
+ * Documentation in `gcc/doc/extend.texi' of any target-specific
+ built-in functions supported.
+
+ * Documentation in `gcc/doc/md.texi' of any target-specific
+ constraint letters (*note Constraints for Particular Machines:
+ Machine Constraints.).
+
+ * A note in `gcc/doc/contrib.texi' under the person or people who
+ contributed the target support.
+
+ * Entries in `gcc/doc/install.texi' for all target triplets
+ supported with this target architecture, giving details of any
+ special notes about installation for this target, or saying that
+ there are no special notes if there are none.
+
+ * Possibly other support outside the `gcc' directory for runtime
+ libraries. FIXME: reference docs for this. The libstdc++ porting
+ manual needs to be installed as info for this to work, or to be a
+ chapter of this manual.
+
+ If the back end is added to the official GCC CVS repository, the
+following are also necessary:
+
+ * An entry for the target architecture in `readings.html' on the GCC
+ web site, with any relevant links.
+
+ * A news item about the contribution of support for that target
+ architecture, in `index.html' on the GCC web site.
+
+ * Normally, one or more maintainers of that target listed in
+ `MAINTAINERS'. Some existing architectures may be unmaintained,
+ but it would be unusual to add support for a target that does not
+ have a maintainer when support is added.
+
+\1f
+File: gccint.info, Node: Test Suites, Prev: gcc Directory, Up: Source Tree
+
+5.4 Test Suites
+===============
+
+GCC contains several test suites to help maintain compiler quality.
+Most of the runtime libraries and language front ends in GCC have test
+suites. Currently only the C language test suites are documented here;
+FIXME: document the others.
+
+* Menu:
+
+* Test Idioms:: Idioms used in test suite code.
+* C Tests:: The C language test suites.
+* libgcj Tests:: The Java library test suites.
+
+\1f
+File: gccint.info, Node: Test Idioms, Next: C Tests, Up: Test Suites
+
+5.4.1 Idioms Used in Test Suite Code
+------------------------------------
+
+In the `gcc.c-torture' test suites, test cases are commonly named after
+the date on which they were added. This allows people to tell at a
+glance whether a test failure is because of a recently found bug that
+has not yet been fixed, or whether it may be a regression. In other
+test suites, more descriptive names are used. In general C test cases
+have a trailing `-N.c', starting with `-1.c', in case other test cases
+with similar names are added later.
+
+ Test cases should use `abort ()' to indicate failure and `exit (0)'
+for success; on some targets these may be redefined to indicate failure
+and success in other ways.
+
+ In the `gcc.dg' test suite, it is often necessary to test that an
+error is indeed a hard error and not just a warning--for example, where
+it is a constraint violation in the C standard, which must become an
+error with `-pedantic-errors'. The following idiom, where the first
+line shown is line LINE of the file and the line that generates the
+error, is used for this:
+
+ /* { dg-bogus "warning" "warning in place of error" } */
+ /* { dg-error "REGEXP" "MESSAGE" { target *-*-* } LINE } */
+
+ It may be necessary to check that an expression is an integer
+constant expression and has a certain value. To check that `E' has
+value `V', an idiom similar to the following is used:
+
+ char x[((E) == (V) ? 1 : -1)];
+
+ In `gcc.dg' tests, `__typeof__' is sometimes used to make assertions
+about the types of expressions. See, for example,
+`gcc.dg/c99-condexpr-1.c'. The more subtle uses depend on the exact
+rules for the types of conditional expressions in the C standard; see,
+for example, `gcc.dg/c99-intconst-1.c'.
+
+ It is useful to be able to test that optimizations are being made
+properly. This cannot be done in all cases, but it can be done where
+the optimization will lead to code being optimized away (for example,
+where flow analysis or alias analysis should show that certain code
+cannot be called) or to functions not being called because they have
+been expanded as built-in functions. Such tests go in
+`gcc.c-torture/execute'. Where code should be optimized away, a call
+to a nonexistent function such as `link_failure ()' may be inserted; a
+definition
+
+ #ifndef __OPTIMIZE__
+ void
+ link_failure (void)
+ {
+ abort ();
+ }
+ #endif
+
+will also be needed so that linking still succeeds when the test is run
+without optimization. When all calls to a built-in function should
+have been optimized and no calls to the non-built-in version of the
+function should remain, that function may be defined as `static' to
+call `abort ()' (although redeclaring a function as static may not work
+on all targets).
+
+ FIXME: discuss non-C test suites here.
+
+\1f
+File: gccint.info, Node: C Tests, Next: libgcj Tests, Prev: Test Idioms, Up: Test Suites
+
+5.4.2 C Language Test Suites
+----------------------------
+
+GCC contains the following C language test suites, in the
+`gcc/testsuite' directory:
+
+`gcc.c-torture/compat'
+ FIXME: describe this.
+
+ This directory should probably not be used for new tests.
+
+`gcc.c-torture/compile'
+ This test suite contains test cases that should compile, but do not
+ need to link or run. These test cases are compiled with several
+ different combinations of optimization options. All warnings are
+ disabled for these test cases, so this directory is not suitable if
+ you wish to test for the presence or absence of compiler warnings.
+ While special options can be set, and tests disabled on specific
+ platforms, by the use of `.x' files, mostly these test cases
+ should not contain platform dependencies. FIXME: discuss how
+ defines such as `NO_LABEL_VALUES' and `STACK_SIZE' are used.
+
+`gcc.c-torture/execute'
+ This test suite contains test cases that should compile, link and
+ run; otherwise the same comments as for `gcc.c-torture/compile'
+ apply.
+
+`gcc.c-torture/unsorted'
+ FIXME: describe this.
+
+ This directory should probably not be used for new tests.
+
+`gcc.dg'
+ This test suite contains tests using the more modern `dg' harness.
+ Magic comments determine whether the file is preprocessed,
+ compiled, linked or run. In these tests, error and warning
+ message texts are compared against expected texts or regular
+ expressions given in comments. These tests are run with the
+ options `-ansi -pedantic' unless other options are given in the
+ test. Except as noted below they are not run with multiple
+ optimization options.
+
+`gcc.dg/cpp'
+ This subdirectory contains tests of the preprocessor.
+
+`gcc.dg/debug'
+ This subdirectory contains tests for debug formats. Tests in this
+ subdirectory are run for each debug format that the compiler
+ supports.
+
+`gcc.dg/format'
+ This subdirectory contains tests of the `-Wformat' format
+ checking. Tests in this directory are run with and without
+ `-DWIDE'.
+
+`gcc.dg/noncompile'
+ This subdirectory contains tests of code that should not compile
+ and does not need any special compilation options. They are run
+ with multiple optimization options, since sometimes invalid code
+ crashes the compiler with optimization.
+
+`gcc.dg/special'
+ FIXME: describe this.
+
+`gcc.c-torture/misc-tests'
+ FIXME: describe this, when it should be used for new tests and
+ when it shouldn't.
+
+ FIXME: merge in `testsuite/README.gcc' and discuss the format of
+test cases and magic comments more.
+
+\1f
+File: gccint.info, Node: libgcj Tests, Prev: C Tests, Up: Test Suites
+
+5.4.3 The Java library test suites.
+-----------------------------------
+
+Runtime tests are executed via `make check' from the `testsuite'
+directory of the libjava hierarchy in the build tree. Additional
+runtime tests can be checked into this testsuite.
+
+ Regression testing of the core packages in libgcj is also covered by
+the Mauve test suite. The Mauve Project develops tests for the Java
+Class Libraries. These tests are run as part of libgcj testing by
+specifying the location of the Mauve tree when invoking `make', as in
+`make MAUVEDIR=~/mauve check'.
+
+ The Jacks project provides a test suite for Java compilers that can
+be used to test changes that affect the GCJ front end. There is no
+automated mechanism to run the Jacks suite as part of GCJ testing.
+
+ We encourage developers to contribute test cases to Mauve and Jacks.
+
+\1f
+File: gccint.info, Node: Passes, Next: Trees, Prev: Source Tree, Up: Top
+
+6 Passes and Files of the Compiler
+**********************************
+
+The overall control structure of the compiler is in `toplev.c'. This
+file is responsible for initialization, decoding arguments, opening and
+closing files, and sequencing the passes.
+
+ The parsing pass is invoked only once, to parse the entire input. A
+high level tree representation is then generated from the input, one
+function at a time. This tree code is then transformed into RTL
+intermediate code, and processed. The files involved in transforming
+the trees into RTL are `expr.c', `expmed.c', and `stmt.c'. The order
+of trees that are processed, is not necessarily the same order they are
+generated from the input, due to deferred inlining, and other
+considerations.
+
+ Each time the parsing pass reads a complete function definition or
+top-level declaration, it calls either the function
+`rest_of_compilation', or the function `rest_of_decl_compilation' in
+`toplev.c', which are responsible for all further processing necessary,
+ending with output of the assembler language. All other compiler
+passes run, in sequence, within `rest_of_compilation'. When that
+function returns from compiling a function definition, the storage used
+for that function definition's compilation is entirely freed, unless it
+is an inline function, or was deferred for some reason (this can occur
+in templates, for example). (*note An Inline Function is As Fast As a
+Macro: (gcc)Inline.).
+
+ Here is a list of all the passes of the compiler and their source
+files. Also included is a description of where debugging dumps can be
+requested with `-d' options.
+
+ * Parsing. This pass reads the entire text of a function definition,
+ constructing a high level tree representation. (Because of the
+ semantic analysis that takes place during this pass, it does more
+ than is formally considered to be parsing.)
+
+ The tree representation does not entirely follow C syntax, because
+ it is intended to support other languages as well.
+
+ Language-specific data type analysis is also done in this pass,
+ and every tree node that represents an expression has a data type
+ attached. Variables are represented as declaration nodes.
+
+ The language-independent source files for parsing are `tree.c',
+ `fold-const.c', and `stor-layout.c'. There are also header files
+ `tree.h' and `tree.def' which define the format of the tree
+ representation.
+
+ C preprocessing, for language front ends, that want or require it,
+ is performed by cpplib, which is covered in separate
+ documentation. In particular, the internals are covered in *Note
+ Cpplib internals: (cppinternals)Top.
+
+ The source files to parse C are `c-convert.c', `c-decl.c',
+ `c-errors.c', `c-lang.c', `c-objc-common.c', `c-parse.in',
+ `c-aux-info.c', and `c-typeck.c', along with a header file
+ `c-tree.h' and some files shared with Objective-C and C++.
+
+ The source files for parsing C++ are in `cp/'. They are `parse.y',
+ `class.c', `cvt.c', `decl.c', `decl2.c', `except.c', `expr.c',
+ `init.c', `lex.c', `method.c', `ptree.c', `search.c', `spew.c',
+ `semantics.c', `tree.c', `typeck2.c', and `typeck.c', along with
+ header files `cp-tree.def', `cp-tree.h', and `decl.h'.
+
+ The special source files for parsing Objective-C are in `objc/'.
+ They are `objc-act.c', `objc-tree.def', and `objc-act.h'. Certain
+ C-specific files are used for this as well.
+
+ The files `c-common.c', `c-common.def', `c-format.c', `c-pragma.c',
+ `c-semantics.c', and `c-lex.c', along with header files
+ `c-common.h', `c-dump.h', `c-lex.h', and `c-pragma.h', are also
+ used for all of the above languages.
+
+ * Tree optimization. This is the optimization of the tree
+ representation, before converting into RTL code.
+
+ Currently, the main optimization performed here is tree-based
+ inlining. This is implemented in `tree-inline.c' and used by both
+ C and C++. Note that tree based inlining turns off rtx based
+ inlining (since it's more powerful, it would be a waste of time to
+ do rtx based inlining in addition).
+
+ Constant folding and some arithmetic simplifications are also done
+ during this pass, on the tree representation. The routines that
+ perform these tasks are located in `fold-const.c'.
+
+ * RTL generation. This is the conversion of syntax tree into RTL
+ code.
+
+ This is where the bulk of target-parameter-dependent code is found,
+ since often it is necessary for strategies to apply only when
+ certain standard kinds of instructions are available. The purpose
+ of named instruction patterns is to provide this information to
+ the RTL generation pass.
+
+ Optimization is done in this pass for `if'-conditions that are
+ comparisons, boolean operations or conditional expressions. Tail
+ recursion is detected at this time also. Decisions are made about
+ how best to arrange loops and how to output `switch' statements.
+
+ The source files for RTL generation include `stmt.c', `calls.c',
+ `expr.c', `explow.c', `expmed.c', `function.c', `optabs.c' and
+ `emit-rtl.c'. Also, the file `insn-emit.c', generated from the
+ machine description by the program `genemit', is used in this
+ pass. The header file `expr.h' is used for communication within
+ this pass.
+
+ The header files `insn-flags.h' and `insn-codes.h', generated from
+ the machine description by the programs `genflags' and `gencodes',
+ tell this pass which standard names are available for use and
+ which patterns correspond to them.
+
+ Aside from debugging information output, none of the following
+ passes refers to the tree structure representation of the function
+ (only part of which is saved).
+
+ The decision of whether the function can and should be expanded
+ inline in its subsequent callers is made at the end of rtl
+ generation. The function must meet certain criteria, currently
+ related to the size of the function and the types and number of
+ parameters it has. Note that this function may contain loops,
+ recursive calls to itself (tail-recursive functions can be
+ inlined!), gotos, in short, all constructs supported by GCC. The
+ file `integrate.c' contains the code to save a function's rtl for
+ later inlining and to inline that rtl when the function is called.
+ The header file `integrate.h' is also used for this purpose.
+
+ The option `-dr' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.rtl' to
+ the input file name.
+
+ * Sibiling call optimization. This pass performs tail recursion
+ elimination, and tail and sibling call optimizations. The purpose
+ of these optimizations is to reduce the overhead of function calls,
+ whenever possible.
+
+ The source file of this pass is `sibcall.c'
+
+ The option `-di' causes a debugging dump of the RTL code after
+ this pass is run. This dump file's name is made by appending
+ `.sibling' to the input file name.
+
+ * Jump optimization. This pass simplifies jumps to the following
+ instruction, jumps across jumps, and jumps to jumps. It deletes
+ unreferenced labels and unreachable code, except that unreachable
+ code that contains a loop is not recognized as unreachable in this
+ pass. (Such loops are deleted later in the basic block analysis.)
+ It also converts some code originally written with jumps into
+ sequences of instructions that directly set values from the
+ results of comparisons, if the machine has such instructions.
+
+ Jump optimization is performed two or three times. The first time
+ is immediately following RTL generation. The second time is after
+ CSE, but only if CSE says repeated jump optimization is needed.
+ The last time is right before the final pass. That time,
+ cross-jumping and deletion of no-op move instructions are done
+ together with the optimizations described above.
+
+ The source file of this pass is `jump.c'.
+
+ The option `-dj' causes a debugging dump of the RTL code after
+ this pass is run for the first time. This dump file's name is
+ made by appending `.jump' to the input file name.
+
+ * Register scan. This pass finds the first and last use of each
+ register, as a guide for common subexpression elimination. Its
+ source is in `regclass.c'.
+
+ * Jump threading. This pass detects a condition jump that branches
+ to an identical or inverse test. Such jumps can be `threaded'
+ through the second conditional test. The source code for this
+ pass is in `jump.c'. This optimization is only performed if
+ `-fthread-jumps' is enabled.
+
+ * Static Single Assignment (SSA) based optimization passes. The SSA
+ conversion passes (to/from) are turned on by the `-fssa' option
+ (it is also done automatically if you enable an SSA optimization
+ pass). These passes utilize a form called Static Single
+ Assignment. In SSA form, each variable (pseudo register) is only
+ set once, giving you def-use and use-def chains for free, and
+ enabling a lot more optimization passes to be run in linear time.
+ Conversion to and from SSA form is handled by functions in `ssa.c'.
+
+ The option `-de' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.ssa' to
+ the input file name.
+ * SSA Conditional Constant Propagation. Turned on by the
+ `-fssa-ccp' option. This pass performs conditional constant
+ propagation to simplify instructions including conditional
+ branches. This pass is more aggressive than the constant
+ propagation done by the CSE and GCSE passes, but operates in
+ linear time.
+
+ The option `-dW' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending
+ `.ssaccp' to the input file name.
+
+ * SSA Aggressive Dead Code Elimination. Turned on by the
+ `-fssa-dce' option. This pass performs elimination of code
+ considered unnecessary because it has no externally visible
+ effects on the program. It operates in linear time.
+
+ The option `-dX' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending
+ `.ssadce' to the input file name.
+
+ * Common subexpression elimination. This pass also does constant
+ propagation. Its source files are `cse.c', and `cselib.c'. If
+ constant propagation causes conditional jumps to become
+ unconditional or to become no-ops, jump optimization is run again
+ when CSE is finished.
+
+ The option `-ds' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.cse' to
+ the input file name.
+
+ * Global common subexpression elimination. This pass performs two
+ different types of GCSE depending on whether you are optimizing
+ for size or not (LCM based GCSE tends to increase code size for a
+ gain in speed, while Morel-Renvoise based GCSE does not). When
+ optimizing for size, GCSE is done using Morel-Renvoise Partial
+ Redundancy Elimination, with the exception that it does not try to
+ move invariants out of loops--that is left to the loop
+ optimization pass. If MR PRE GCSE is done, code hoisting (aka
+ unification) is also done, as well as load motion. If you are
+ optimizing for speed, LCM (lazy code motion) based GCSE is done.
+ LCM is based on the work of Knoop, Ruthing, and Steffen. LCM
+ based GCSE also does loop invariant code motion. We also perform
+ load and store motion when optimizing for speed. Regardless of
+ which type of GCSE is used, the GCSE pass also performs global
+ constant and copy propagation.
+
+ The source file for this pass is `gcse.c', and the LCM routines
+ are in `lcm.c'.
+
+ The option `-dG' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.gcse' to
+ the input file name.
+
+ * Loop optimization. This pass moves constant expressions out of
+ loops, and optionally does strength-reduction and loop unrolling
+ as well. Its source files are `loop.c' and `unroll.c', plus the
+ header `loop.h' used for communication between them. Loop
+ unrolling uses some functions in `integrate.c' and the header
+ `integrate.h'. Loop dependency analysis routines are contained in
+ `dependence.c'.
+
+ The option `-dL' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.loop' to
+ the input file name.
+
+ * If `-frerun-cse-after-loop' was enabled, a second common
+ subexpression elimination pass is performed after the loop
+ optimization pass. Jump threading is also done again at this time
+ if it was specified.
+
+ The option `-dt' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.cse2' to
+ the input file name.
+
+ * Data flow analysis (`flow.c'). This pass divides the program into
+ basic blocks (and in the process deletes unreachable loops); then
+ it computes which pseudo-registers are live at each point in the
+ program, and makes the first instruction that uses a value point at
+ the instruction that computed the value.
+
+ This pass also deletes computations whose results are never used,
+ and combines memory references with add or subtract instructions
+ to make autoincrement or autodecrement addressing.
+
+ The option `-df' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.flow' to
+ the input file name. If stupid register allocation is in use, this
+ dump file reflects the full results of such allocation.
+
+ * Instruction combination (`combine.c'). This pass attempts to
+ combine groups of two or three instructions that are related by
+ data flow into single instructions. It combines the RTL
+ expressions for the instructions by substitution, simplifies the
+ result using algebra, and then attempts to match the result
+ against the machine description.
+
+ The option `-dc' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.combine'
+ to the input file name.
+
+ * If-conversion is a transformation that transforms control
+ dependencies into data dependencies (IE it transforms conditional
+ code into a single control stream). It is implemented in the file
+ `ifcvt.c'.
+
+ The option `-dE' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.ce' to
+ the input file name.
+
+ * Register movement (`regmove.c'). This pass looks for cases where
+ matching constraints would force an instruction to need a reload,
+ and this reload would be a register-to-register move. It then
+ attempts to change the registers used by the instruction to avoid
+ the move instruction.
+
+ The option `-dN' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.regmove'
+ to the input file name.
+
+ * Instruction scheduling (`sched.c'). This pass looks for
+ instructions whose output will not be available by the time that
+ it is used in subsequent instructions. (Memory loads and floating
+ point instructions often have this behavior on RISC machines). It
+ re-orders instructions within a basic block to try to separate the
+ definition and use of items that otherwise would cause pipeline
+ stalls.
+
+ Instruction scheduling is performed twice. The first time is
+ immediately after instruction combination and the second is
+ immediately after reload.
+
+ The option `-dS' causes a debugging dump of the RTL code after this
+ pass is run for the first time. The dump file's name is made by
+ appending `.sched' to the input file name.
+
+ * Register class preferencing. The RTL code is scanned to find out
+ which register class is best for each pseudo register. The source
+ file is `regclass.c'.
+
+ * Local register allocation (`local-alloc.c'). This pass allocates
+ hard registers to pseudo registers that are used only within one
+ basic block. Because the basic block is linear, it can use fast
+ and powerful techniques to do a very good job.
+
+ The option `-dl' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.lreg' to
+ the input file name.
+
+ * Global register allocation (`global.c'). This pass allocates hard
+ registers for the remaining pseudo registers (those whose life
+ spans are not contained in one basic block).
+
+ * Reloading. This pass renumbers pseudo registers with the hardware
+ registers numbers they were allocated. Pseudo registers that did
+ not get hard registers are replaced with stack slots. Then it
+ finds instructions that are invalid because a value has failed to
+ end up in a register, or has ended up in a register of the wrong
+ kind. It fixes up these instructions by reloading the
+ problematical values temporarily into registers. Additional
+ instructions are generated to do the copying.
+
+ The reload pass also optionally eliminates the frame pointer and
+ inserts instructions to save and restore call-clobbered registers
+ around calls.
+
+ Source files are `reload.c' and `reload1.c', plus the header
+ `reload.h' used for communication between them.
+
+ The option `-dg' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.greg' to
+ the input file name.
+
+ * Instruction scheduling is repeated here to try to avoid pipeline
+ stalls due to memory loads generated for spilled pseudo registers.
+
+ The option `-dR' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.sched2'
+ to the input file name.
+
+ * Basic block reordering. This pass implements profile guided code
+ positioning. If profile information is not available, various
+ types of static analysis are performed to make the predictions
+ normally coming from the profile feedback (IE execution frequency,
+ branch probability, etc). It is implemented in the file
+ `bb-reorder.c', and the various prediction routines are in
+ `predict.c'.
+
+ The option `-dB' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.bbro' to
+ the input file name.
+
+ * Delayed branch scheduling. This optional pass attempts to find
+ instructions that can go into the delay slots of other
+ instructions, usually jumps and calls. The source file name is
+ `reorg.c'.
+
+ The option `-dd' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.dbr' to
+ the input file name.
+
+ * Branch shortening. On many RISC machines, branch instructions
+ have a limited range. Thus, longer sequences of instructions must
+ be used for long branches. In this pass, the compiler figures out
+ what how far each instruction will be from each other instruction,
+ and therefore whether the usual instructions, or the longer
+ sequences, must be used for each branch.
+
+ * Conversion from usage of some hard registers to usage of a register
+ stack may be done at this point. Currently, this is supported only
+ for the floating-point registers of the Intel 80387 coprocessor.
+ The source file name is `reg-stack.c'.
+
+ The options `-dk' causes a debugging dump of the RTL code after
+ this pass. This dump file's name is made by appending `.stack' to
+ the input file name.
+
+ * Final. This pass outputs the assembler code for the function. It
+ is also responsible for identifying spurious test and compare
+ instructions. Machine-specific peephole optimizations are
+ performed at the same time. The function entry and exit sequences
+ are generated directly as assembler code in this pass; they never
+ exist as RTL.
+
+ The source files are `final.c' plus `insn-output.c'; the latter is
+ generated automatically from the machine description by the tool
+ `genoutput'. The header file `conditions.h' is used for
+ communication between these files.
+
+ * Debugging information output. This is run after final because it
+ must output the stack slot offsets for pseudo registers that did
+ not get hard registers. Source files are `dbxout.c' for DBX
+ symbol table format, `sdbout.c' for SDB symbol table format,
+ `dwarfout.c' for DWARF symbol table format, files `dwarf2out.c' and
+ `dwarf2asm.c' for DWARF2 symbol table format, and `vmsdbgout.c'
+ for VMS debug symbol table format.
+
+ Some additional files are used by all or many passes:
+
+ * Every pass uses `machmode.def' and `machmode.h' which define the
+ machine modes.
+
+ * Several passes use `real.h', which defines the default
+ representation of floating point constants and how to operate on
+ them.
+
+ * All the passes that work with RTL use the header files `rtl.h' and
+ `rtl.def', and subroutines in file `rtl.c'. The tools `gen*' also
+ use these files to read and work with the machine description RTL.
+
+ * All the tools that read the machine description use support
+ routines found in `gensupport.c', `errors.c', and `read-rtl.c'.
+
+ * Several passes refer to the header file `insn-config.h' which
+ contains a few parameters (C macro definitions) generated
+ automatically from the machine description RTL by the tool
+ `genconfig'.
+
+ * Several passes use the instruction recognizer, which consists of
+ `recog.c' and `recog.h', plus the files `insn-recog.c' and
+ `insn-extract.c' that are generated automatically from the machine
+ description by the tools `genrecog' and `genextract'.
+
+ * Several passes use the header files `regs.h' which defines the
+ information recorded about pseudo register usage, and
+ `basic-block.h' which defines the information recorded about basic
+ blocks.
+
+ * `hard-reg-set.h' defines the type `HARD_REG_SET', a bit-vector
+ with a bit for each hard register, and some macros to manipulate
+ it. This type is just `int' if the machine has few enough hard
+ registers; otherwise it is an array of `int' and some of the
+ macros expand into loops.
+
+ * Several passes use instruction attributes. A definition of the
+ attributes defined for a particular machine is in file
+ `insn-attr.h', which is generated from the machine description by
+ the program `genattr'. The file `insn-attrtab.c' contains
+ subroutines to obtain the attribute values for insns. It is
+ generated from the machine description by the program `genattrtab'.
+
+\1f
+File: gccint.info, Node: Trees, Next: RTL, Prev: Passes, Up: Top
+
+7 Trees: The intermediate representation used by the C and C++ front ends
+*************************************************************************
+
+This chapter documents the internal representation used by GCC to
+represent C and C++ source programs. When presented with a C or C++
+source program, GCC parses the program, performs semantic analysis
+(including the generation of error messages), and then produces the
+internal representation described here. This representation contains a
+complete representation for the entire translation unit provided as
+input to the front end. This representation is then typically processed
+by a code-generator in order to produce machine code, but could also be
+used in the creation of source browsers, intelligent editors, automatic
+documentation generators, interpreters, and any other programs needing
+the ability to process C or C++ code.
+
+ This chapter explains the internal representation. In particular, it
+documents the internal representation for C and C++ source constructs,
+and the macros, functions, and variables that can be used to access
+these constructs. The C++ representation is largely a superset of the
+representation used in the C front end. There is only one construct
+used in C that does not appear in the C++ front end and that is the GNU
+"nested function" extension. Many of the macros documented here do not
+apply in C because the corresponding language constructs do not appear
+in C.
+
+ If you are developing a "back end", be it is a code-generator or some
+other tool, that uses this representation, you may occasionally find
+that you need to ask questions not easily answered by the functions and
+macros available here. If that situation occurs, it is quite likely
+that GCC already supports the functionality you desire, but that the
+interface is simply not documented here. In that case, you should ask
+the GCC maintainers (via mail to <gcc@gcc.gnu.org>) about documenting
+the functionality you require. Similarly, if you find yourself writing
+functions that do not deal directly with your back end, but instead
+might be useful to other people using the GCC front end, you should
+submit your patches for inclusion in GCC.
+
+* Menu:
+
+* Deficiencies:: Topics net yet covered in this document.
+* Tree overview:: All about `tree's.
+* Types:: Fundamental and aggregate types.
+* Scopes:: Namespaces and classes.
+* Functions:: Overloading, function bodies, and linkage.
+* Declarations:: Type declarations and variables.
+* Attributes:: Declaration and type attributes.
+* Expression trees:: From `typeid' to `throw'.
+
+\1f
+File: gccint.info, Node: Deficiencies, Next: Tree overview, Up: Trees
+
+7.1 Deficiencies
+================
+
+There are many places in which this document is incomplet and incorrekt.
+It is, as of yet, only _preliminary_ documentation.
+
+\1f
+File: gccint.info, Node: Tree overview, Next: Types, Prev: Deficiencies, Up: Trees
+
+7.2 Overview
+============
+
+The central data structure used by the internal representation is the
+`tree'. These nodes, while all of the C type `tree', are of many
+varieties. A `tree' is a pointer type, but the object to which it
+points may be of a variety of types. From this point forward, we will
+refer to trees in ordinary type, rather than in `this font', except
+when talking about the actual C type `tree'.
+
+ You can tell what kind of node a particular tree is by using the
+`TREE_CODE' macro. Many, many macros take a trees as input and return
+trees as output. However, most macros require a certain kinds of tree
+node as input. In other words, there is a type-system for trees, but
+it is not reflected in the C type-system.
+
+ For safety, it is useful to configure GCC with `--enable-checking'.
+Although this results in a significant performance penalty (since all
+tree types are checked at run-time), and is therefore inappropriate in a
+release version, it is extremely helpful during the development process.
+
+ Many macros behave as predicates. Many, although not all, of these
+predicates end in `_P'. Do not rely on the result type of these macros
+being of any particular type. You may, however, rely on the fact that
+the type can be compared to `0', so that statements like
+ if (TEST_P (t) && !TEST_P (y))
+ x = 1;
+ and
+ int i = (TEST_P (t) != 0);
+ are legal. Macros that return `int' values now may be changed to
+return `tree' values, or other pointers in the future. Even those that
+continue to return `int' may return multiple nonzero codes where
+previously they returned only zero and one. Therefore, you should not
+write code like
+ if (TEST_P (t) == 1)
+ as this code is not guaranteed to work correctly in the future.
+
+ You should not take the address of values returned by the macros or
+functions described here. In particular, no guarantee is given that the
+values are lvalues.
+
+ In general, the names of macros are all in uppercase, while the
+names of functions are entirely in lower case. There are rare
+exceptions to this rule. You should assume that any macro or function
+whose name is made up entirely of uppercase letters may evaluate its
+arguments more than once. You may assume that a macro or function
+whose name is made up entirely of lowercase letters will evaluate its
+arguments only once.
+
+ The `error_mark_node' is a special tree. Its tree code is
+`ERROR_MARK', but since there is only ever one node with that code, the
+usual practice is to compare the tree against `error_mark_node'. (This
+test is just a test for pointer equality.) If an error has occurred
+during front-end processing the flag `errorcount' will be set. If the
+front end has encountered code it cannot handle, it will issue a
+message to the user and set `sorrycount'. When these flags are set,
+any macro or function which normally returns a tree of a particular
+kind may instead return the `error_mark_node'. Thus, if you intend to
+do any processing of erroneous code, you must be prepared to deal with
+the `error_mark_node'.
+
+ Occasionally, a particular tree slot (like an operand to an
+expression, or a particular field in a declaration) will be referred to
+as "reserved for the back end." These slots are used to store RTL when
+the tree is converted to RTL for use by the GCC back end. However, if
+that process is not taking place (e.g., if the front end is being hooked
+up to an intelligent editor), then those slots may be used by the back
+end presently in use.
+
+ If you encounter situations that do not match this documentation,
+such as tree nodes of types not mentioned here, or macros documented to
+return entities of a particular kind that instead return entities of
+some different kind, you have found a bug, either in the front end or in
+the documentation. Please report these bugs as you would any other bug.
+
+* Menu:
+
+* Macros and Functions::Macros and functions that can be used with all trees.
+* Identifiers:: The names of things.
+* Containers:: Lists and vectors.
+
+\1f
+File: gccint.info, Node: Macros and Functions, Next: Identifiers, Up: Tree overview
+
+7.2.1 Trees
+-----------
+
+This section is not here yet.
+
+\1f
+File: gccint.info, Node: Identifiers, Next: Containers, Prev: Macros and Functions, Up: Tree overview
+
+7.2.2 Identifiers
+-----------------
+
+An `IDENTIFIER_NODE' represents a slightly more general concept that
+the standard C or C++ concept of identifier. In particular, an
+`IDENTIFIER_NODE' may contain a `$', or other extraordinary characters.
+
+ There are never two distinct `IDENTIFIER_NODE's representing the
+same identifier. Therefore, you may use pointer equality to compare
+`IDENTIFIER_NODE's, rather than using a routine like `strcmp'.
+
+ You can use the following macros to access identifiers:
+`IDENTIFIER_POINTER'
+ The string represented by the identifier, represented as a
+ `char*'. This string is always `NUL'-terminated, and contains no
+ embedded `NUL' characters.
+
+`IDENTIFIER_LENGTH'
+ The length of the string returned by `IDENTIFIER_POINTER', not
+ including the trailing `NUL'. This value of `IDENTIFIER_LENGTH
+ (x)' is always the same as `strlen (IDENTIFIER_POINTER (x))'.
+
+`IDENTIFIER_OPNAME_P'
+ This predicate holds if the identifier represents the name of an
+ overloaded operator. In this case, you should not depend on the
+ contents of either the `IDENTIFIER_POINTER' or the
+ `IDENTIFIER_LENGTH'.
+
+`IDENTIFIER_TYPENAME_P'
+ This predicate holds if the identifier represents the name of a
+ user-defined conversion operator. In this case, the `TREE_TYPE' of
+ the `IDENTIFIER_NODE' holds the type to which the conversion
+ operator converts.
+
+
+\1f
+File: gccint.info, Node: Containers, Prev: Identifiers, Up: Tree overview
+
+7.2.3 Containers
+----------------
+
+Two common container data structures can be represented directly with
+tree nodes. A `TREE_LIST' is a singly linked list containing two trees
+per node. These are the `TREE_PURPOSE' and `TREE_VALUE' of each node.
+(Often, the `TREE_PURPOSE' contains some kind of tag, or additional
+information, while the `TREE_VALUE' contains the majority of the
+payload. In other cases, the `TREE_PURPOSE' is simply `NULL_TREE',
+while in still others both the `TREE_PURPOSE' and `TREE_VALUE' are of
+equal stature.) Given one `TREE_LIST' node, the next node is found by
+following the `TREE_CHAIN'. If the `TREE_CHAIN' is `NULL_TREE', then
+you have reached the end of the list.
+
+ A `TREE_VEC' is a simple vector. The `TREE_VEC_LENGTH' is an
+integer (not a tree) giving the number of nodes in the vector. The
+nodes themselves are accessed using the `TREE_VEC_ELT' macro, which
+takes two arguments. The first is the `TREE_VEC' in question; the
+second is an integer indicating which element in the vector is desired.
+The elements are indexed from zero.
+
+\1f
+File: gccint.info, Node: Types, Next: Scopes, Prev: Tree overview, Up: Trees
+
+7.3 Types
+=========
+
+All types have corresponding tree nodes. However, you should not assume
+that there is exactly one tree node corresponding to each type. There
+are often several nodes each of which correspond to the same type.
+
+ For the most part, different kinds of types have different tree
+codes. (For example, pointer types use a `POINTER_TYPE' code while
+arrays use an `ARRAY_TYPE' code.) However, pointers to member functions
+use the `RECORD_TYPE' code. Therefore, when writing a `switch'
+statement that depends on the code associated with a particular type,
+you should take care to handle pointers to member functions under the
+`RECORD_TYPE' case label.
+
+ In C++, an array type is not qualified; rather the type of the array
+elements is qualified. This situation is reflected in the intermediate
+representation. The macros described here will always examine the
+qualification of the underlying element type when applied to an array
+type. (If the element type is itself an array, then the recursion
+continues until a non-array type is found, and the qualification of this
+type is examined.) So, for example, `CP_TYPE_CONST_P' will hold of the
+type `const int ()[7]', denoting an array of seven `int's.
+
+ The following functions and macros deal with cv-qualification of
+types:
+`CP_TYPE_QUALS'
+ This macro returns the set of type qualifiers applied to this type.
+ This value is `TYPE_UNQUALIFIED' if no qualifiers have been
+ applied. The `TYPE_QUAL_CONST' bit is set if the type is
+ `const'-qualified. The `TYPE_QUAL_VOLATILE' bit is set if the
+ type is `volatile'-qualified. The `TYPE_QUAL_RESTRICT' bit is set
+ if the type is `restrict'-qualified.
+
+`CP_TYPE_CONST_P'
+ This macro holds if the type is `const'-qualified.
+
+`CP_TYPE_VOLATILE_P'
+ This macro holds if the type is `volatile'-qualified.
+
+`CP_TYPE_RESTRICT_P'
+ This macro holds if the type is `restrict'-qualified.
+
+`CP_TYPE_CONST_NON_VOLATILE_P'
+ This predicate holds for a type that is `const'-qualified, but
+ _not_ `volatile'-qualified; other cv-qualifiers are ignored as
+ well: only the `const'-ness is tested.
+
+`TYPE_MAIN_VARIANT'
+ This macro returns the unqualified version of a type. It may be
+ applied to an unqualified type, but it is not always the identity
+ function in that case.
+
+ A few other macros and functions are usable with all types:
+`TYPE_SIZE'
+ The number of bits required to represent the type, represented as
+ an `INTEGER_CST'. For an incomplete type, `TYPE_SIZE' will be
+ `NULL_TREE'.
+
+`TYPE_ALIGN'
+ The alignment of the type, in bits, represented as an `int'.
+
+`TYPE_NAME'
+ This macro returns a declaration (in the form of a `TYPE_DECL') for
+ the type. (Note this macro does _not_ return a `IDENTIFIER_NODE',
+ as you might expect, given its name!) You can look at the
+ `DECL_NAME' of the `TYPE_DECL' to obtain the actual name of the
+ type. The `TYPE_NAME' will be `NULL_TREE' for a type that is not
+ a built-in type, the result of a typedef, or a named class type.
+
+`CP_INTEGRAL_TYPE'
+ This predicate holds if the type is an integral type. Notice that
+ in C++, enumerations are _not_ integral types.
+
+`ARITHMETIC_TYPE_P'
+ This predicate holds if the type is an integral type (in the C++
+ sense) or a floating point type.
+
+`CLASS_TYPE_P'
+ This predicate holds for a class-type.
+
+`TYPE_BUILT_IN'
+ This predicate holds for a built-in type.
+
+`TYPE_PTRMEM_P'
+ This predicate holds if the type is a pointer to data member.
+
+`TYPE_PTR_P'
+ This predicate holds if the type is a pointer type, and the
+ pointee is not a data member.
+
+`TYPE_PTRFN_P'
+ This predicate holds for a pointer to function type.
+
+`TYPE_PTROB_P'
+ This predicate holds for a pointer to object type. Note however
+ that it does not hold for the generic pointer to object type `void
+ *'. You may use `TYPE_PTROBV_P' to test for a pointer to object
+ type as well as `void *'.
+
+`same_type_p'
+ This predicate takes two types as input, and holds if they are the
+ same type. For example, if one type is a `typedef' for the other,
+ or both are `typedef's for the same type. This predicate also
+ holds if the two trees given as input are simply copies of one
+ another; i.e., there is no difference between them at the source
+ level, but, for whatever reason, a duplicate has been made in the
+ representation. You should never use `==' (pointer equality) to
+ compare types; always use `same_type_p' instead.
+
+ Detailed below are the various kinds of types, and the macros that
+can be used to access them. Although other kinds of types are used
+elsewhere in G++, the types described here are the only ones that you
+will encounter while examining the intermediate representation.
+
+`VOID_TYPE'
+ Used to represent the `void' type.
+
+`INTEGER_TYPE'
+ Used to represent the various integral types, including `char',
+ `short', `int', `long', and `long long'. This code is not used
+ for enumeration types, nor for the `bool' type. Note that GCC's
+ `CHAR_TYPE' node is _not_ used to represent `char'. The
+ `TYPE_PRECISION' is the number of bits used in the representation,
+ represented as an `unsigned int'. (Note that in the general case
+ this is not the same value as `TYPE_SIZE'; suppose that there were
+ a 24-bit integer type, but that alignment requirements for the ABI
+ required 32-bit alignment. Then, `TYPE_SIZE' would be an
+ `INTEGER_CST' for 32, while `TYPE_PRECISION' would be 24.) The
+ integer type is unsigned if `TREE_UNSIGNED' holds; otherwise, it
+ is signed.
+
+ The `TYPE_MIN_VALUE' is an `INTEGER_CST' for the smallest integer
+ that may be represented by this type. Similarly, the
+ `TYPE_MAX_VALUE' is an `INTEGER_CST' for the largest integer that
+ may be represented by this type.
+
+`REAL_TYPE'
+ Used to represent the `float', `double', and `long double' types.
+ The number of bits in the floating-point representation is given
+ by `TYPE_PRECISION', as in the `INTEGER_TYPE' case.
+
+`COMPLEX_TYPE'
+ Used to represent GCC built-in `__complex__' data types. The
+ `TREE_TYPE' is the type of the real and imaginary parts.
+
+`ENUMERAL_TYPE'
+ Used to represent an enumeration type. The `TYPE_PRECISION' gives
+ (as an `int'), the number of bits used to represent the type. If
+ there are no negative enumeration constants, `TREE_UNSIGNED' will
+ hold. The minimum and maximum enumeration constants may be
+ obtained with `TYPE_MIN_VALUE' and `TYPE_MAX_VALUE', respectively;
+ each of these macros returns an `INTEGER_CST'.
+
+ The actual enumeration constants themselves may be obtained by
+ looking at the `TYPE_VALUES'. This macro will return a
+ `TREE_LIST', containing the constants. The `TREE_PURPOSE' of each
+ node will be an `IDENTIFIER_NODE' giving the name of the constant;
+ the `TREE_VALUE' will be an `INTEGER_CST' giving the value
+ assigned to that constant. These constants will appear in the
+ order in which they were declared. The `TREE_TYPE' of each of
+ these constants will be the type of enumeration type itself.
+
+`BOOLEAN_TYPE'
+ Used to represent the `bool' type.
+
+`POINTER_TYPE'
+ Used to represent pointer types, and pointer to data member types.
+ The `TREE_TYPE' gives the type to which this type points. If the
+ type is a pointer to data member type, then `TYPE_PTRMEM_P' will
+ hold. For a pointer to data member type of the form `T X::*',
+ `TYPE_PTRMEM_CLASS_TYPE' will be the type `X', while
+ `TYPE_PTRMEM_POINTED_TO_TYPE' will be the type `T'.
+
+`REFERENCE_TYPE'
+ Used to represent reference types. The `TREE_TYPE' gives the type
+ to which this type refers.
+
+`FUNCTION_TYPE'
+ Used to represent the type of non-member functions and of static
+ member functions. The `TREE_TYPE' gives the return type of the
+ function. The `TYPE_ARG_TYPES' are a `TREE_LIST' of the argument
+ types. The `TREE_VALUE' of each node in this list is the type of
+ the corresponding argument; the `TREE_PURPOSE' is an expression
+ for the default argument value, if any. If the last node in the
+ list is `void_list_node' (a `TREE_LIST' node whose `TREE_VALUE' is
+ the `void_type_node'), then functions of this type do not take
+ variable arguments. Otherwise, they do take a variable number of
+ arguments.
+
+ Note that in C (but not in C++) a function declared like `void f()'
+ is an unprototyped function taking a variable number of arguments;
+ the `TYPE_ARG_TYPES' of such a function will be `NULL'.
+
+`METHOD_TYPE'
+ Used to represent the type of a non-static member function. Like a
+ `FUNCTION_TYPE', the return type is given by the `TREE_TYPE'. The
+ type of `*this', i.e., the class of which functions of this type
+ are a member, is given by the `TYPE_METHOD_BASETYPE'. The
+ `TYPE_ARG_TYPES' is the parameter list, as for a `FUNCTION_TYPE',
+ and includes the `this' argument.
+
+`ARRAY_TYPE'
+ Used to represent array types. The `TREE_TYPE' gives the type of
+ the elements in the array. If the array-bound is present in the
+ type, the `TYPE_DOMAIN' is an `INTEGER_TYPE' whose
+ `TYPE_MIN_VALUE' and `TYPE_MAX_VALUE' will be the lower and upper
+ bounds of the array, respectively. The `TYPE_MIN_VALUE' will
+ always be an `INTEGER_CST' for zero, while the `TYPE_MAX_VALUE'
+ will be one less than the number of elements in the array, i.e.,
+ the highest value which may be used to index an element in the
+ array.
+
+`RECORD_TYPE'
+ Used to represent `struct' and `class' types, as well as pointers
+ to member functions and similar constructs in other languages.
+ `TYPE_FIELDS' contains the items contained in this type, each of
+ which can be a `FIELD_DECL', `VAR_DECL', `CONST_DECL', or
+ `TYPE_DECL'. You may not make any assumptions about the ordering
+ of the fields in the type or whether one or more of them overlap.
+ If `TYPE_PTRMEMFUNC_P' holds, then this type is a pointer-to-member
+ type. In that case, the `TYPE_PTRMEMFUNC_FN_TYPE' is a
+ `POINTER_TYPE' pointing to a `METHOD_TYPE'. The `METHOD_TYPE' is
+ the type of a function pointed to by the pointer-to-member
+ function. If `TYPE_PTRMEMFUNC_P' does not hold, this type is a
+ class type. For more information, see *note Classes::.
+
+`UNION_TYPE'
+ Used to represent `union' types. Similar to `RECORD_TYPE' except
+ that all `FIELD_DECL' nodes in `TYPE_FIELD' start at bit position
+ zero.
+
+`QUAL_UNION_TYPE'
+ Used to represent part of a variant record in Ada. Similar to
+ `UNION_TYPE' except that each `FIELD_DECL' has a `DECL_QUALIFIER'
+ field, which contains a boolean expression that indicates whether
+ the field is present in the object. The type will only have one
+ field, so each field's `DECL_QUALIFIER' is only evaluated if none
+ of the expressions in the previous fields in `TYPE_FIELDS' are
+ nonzero. Normally these expressions will reference a field in the
+ outer object using a `PLACEHOLDER_EXPR'.
+
+`UNKNOWN_TYPE'
+ This node is used to represent a type the knowledge of which is
+ insufficient for a sound processing.
+
+`OFFSET_TYPE'
+ This node is used to represent a data member; for example a
+ pointer-to-data-member is represented by a `POINTER_TYPE' whose
+ `TREE_TYPE' is an `OFFSET_TYPE'. For a data member `X::m' the
+ `TYPE_OFFSET_BASETYPE' is `X' and the `TREE_TYPE' is the type of
+ `m'.
+
+`TYPENAME_TYPE'
+ Used to represent a construct of the form `typename T::A'. The
+ `TYPE_CONTEXT' is `T'; the `TYPE_NAME' is an `IDENTIFIER_NODE' for
+ `A'. If the type is specified via a template-id, then
+ `TYPENAME_TYPE_FULLNAME' yields a `TEMPLATE_ID_EXPR'. The
+ `TREE_TYPE' is non-`NULL' if the node is implicitly generated in
+ support for the implicit typename extension; in which case the
+ `TREE_TYPE' is a type node for the base-class.
+
+`TYPEOF_TYPE'
+ Used to represent the `__typeof__' extension. The `TYPE_FIELDS'
+ is the expression the type of which is being represented.
+
+ There are variables whose values represent some of the basic types.
+These include:
+`void_type_node'
+ A node for `void'.
+
+`integer_type_node'
+ A node for `int'.
+
+`unsigned_type_node.'
+ A node for `unsigned int'.
+
+`char_type_node.'
+ A node for `char'.
+ It may sometimes be useful to compare one of these variables with a
+type in hand, using `same_type_p'.
+
+\1f
+File: gccint.info, Node: Scopes, Next: Functions, Prev: Types, Up: Trees
+
+7.4 Scopes
+==========
+
+The root of the entire intermediate representation is the variable
+`global_namespace'. This is the namespace specified with `::' in C++
+source code. All other namespaces, types, variables, functions, and so
+forth can be found starting with this namespace.
+
+ Besides namespaces, the other high-level scoping construct in C++ is
+the class. (Throughout this manual the term "class" is used to mean the
+types referred to in the ANSI/ISO C++ Standard as classes; these include
+types defined with the `class', `struct', and `union' keywords.)
+
+* Menu:
+
+* Namespaces:: Member functions, types, etc.
+* Classes:: Members, bases, friends, etc.
+
+\1f
+File: gccint.info, Node: Namespaces, Next: Classes, Up: Scopes
+
+7.4.1 Namespaces
+----------------
+
+A namespace is represented by a `NAMESPACE_DECL' node.
+
+ However, except for the fact that it is distinguished as the root of
+the representation, the global namespace is no different from any other
+namespace. Thus, in what follows, we describe namespaces generally,
+rather than the global namespace in particular.
+
+ The following macros and functions can be used on a `NAMESPACE_DECL':
+
+`DECL_NAME'
+ This macro is used to obtain the `IDENTIFIER_NODE' corresponding to
+ the unqualified name of the name of the namespace (*note
+ Identifiers::). The name of the global namespace is `::', even
+ though in C++ the global namespace is unnamed. However, you
+ should use comparison with `global_namespace', rather than
+ `DECL_NAME' to determine whether or not a namespaces is the global
+ one. An unnamed namespace will have a `DECL_NAME' equal to
+ `anonymous_namespace_name'. Within a single translation unit, all
+ unnamed namespaces will have the same name.
+
+`DECL_CONTEXT'
+ This macro returns the enclosing namespace. The `DECL_CONTEXT' for
+ the `global_namespace' is `NULL_TREE'.
+
+`DECL_NAMESPACE_ALIAS'
+ If this declaration is for a namespace alias, then
+ `DECL_NAMESPACE_ALIAS' is the namespace for which this one is an
+ alias.
+
+ Do not attempt to use `cp_namespace_decls' for a namespace which is
+ an alias. Instead, follow `DECL_NAMESPACE_ALIAS' links until you
+ reach an ordinary, non-alias, namespace, and call
+ `cp_namespace_decls' there.
+
+`DECL_NAMESPACE_STD_P'
+ This predicate holds if the namespace is the special `::std'
+ namespace.
+
+`cp_namespace_decls'
+ This function will return the declarations contained in the
+ namespace, including types, overloaded functions, other
+ namespaces, and so forth. If there are no declarations, this
+ function will return `NULL_TREE'. The declarations are connected
+ through their `TREE_CHAIN' fields.
+
+ Although most entries on this list will be declarations,
+ `TREE_LIST' nodes may also appear. In this case, the `TREE_VALUE'
+ will be an `OVERLOAD'. The value of the `TREE_PURPOSE' is
+ unspecified; back ends should ignore this value. As with the
+ other kinds of declarations returned by `cp_namespace_decls', the
+ `TREE_CHAIN' will point to the next declaration in this list.
+
+ For more information on the kinds of declarations that can occur
+ on this list, *Note Declarations::. Some declarations will not
+ appear on this list. In particular, no `FIELD_DECL',
+ `LABEL_DECL', or `PARM_DECL' nodes will appear here.
+
+ This function cannot be used with namespaces that have
+ `DECL_NAMESPACE_ALIAS' set.
+
+
+\1f
+File: gccint.info, Node: Classes, Prev: Namespaces, Up: Scopes
+
+7.4.2 Classes
+-------------
+
+A class type is represented by either a `RECORD_TYPE' or a
+`UNION_TYPE'. A class declared with the `union' tag is represented by
+a `UNION_TYPE', while classes declared with either the `struct' or the
+`class' tag are represented by `RECORD_TYPE's. You can use the
+`CLASSTYPE_DECLARED_CLASS' macro to discern whether or not a particular
+type is a `class' as opposed to a `struct'. This macro will be true
+only for classes declared with the `class' tag.
+
+ Almost all non-function members are available on the `TYPE_FIELDS'
+list. Given one member, the next can be found by following the
+`TREE_CHAIN'. You should not depend in any way on the order in which
+fields appear on this list. All nodes on this list will be `DECL'
+nodes. A `FIELD_DECL' is used to represent a non-static data member, a
+`VAR_DECL' is used to represent a static data member, and a `TYPE_DECL'
+is used to represent a type. Note that the `CONST_DECL' for an
+enumeration constant will appear on this list, if the enumeration type
+was declared in the class. (Of course, the `TYPE_DECL' for the
+enumeration type will appear here as well.) There are no entries for
+base classes on this list. In particular, there is no `FIELD_DECL' for
+the "base-class portion" of an object.
+
+ The `TYPE_VFIELD' is a compiler-generated field used to point to
+virtual function tables. It may or may not appear on the `TYPE_FIELDS'
+list. However, back ends should handle the `TYPE_VFIELD' just like all
+the entries on the `TYPE_FIELDS' list.
+
+ The function members are available on the `TYPE_METHODS' list.
+Again, subsequent members are found by following the `TREE_CHAIN'
+field. If a function is overloaded, each of the overloaded functions
+appears; no `OVERLOAD' nodes appear on the `TYPE_METHODS' list.
+Implicitly declared functions (including default constructors, copy
+constructors, assignment operators, and destructors) will appear on
+this list as well.
+
+ Every class has an associated "binfo", which can be obtained with
+`TYPE_BINFO'. Binfos are used to represent base-classes. The binfo
+given by `TYPE_BINFO' is the degenerate case, whereby every class is
+considered to be its own base-class. The base classes for a particular
+binfo can be obtained with `BINFO_BASETYPES'. These base-classes are
+themselves binfos. The class type associated with a binfo is given by
+`BINFO_TYPE'. It is always the case that `BINFO_TYPE (TYPE_BINFO (x))'
+is the same type as `x', up to qualifiers. However, it is not always
+the case that `TYPE_BINFO (BINFO_TYPE (y))' is always the same binfo as
+`y'. The reason is that if `y' is a binfo representing a base-class
+`B' of a derived class `D', then `BINFO_TYPE (y)' will be `B', and
+`TYPE_BINFO (BINFO_TYPE (y))' will be `B' as its own base-class, rather
+than as a base-class of `D'.
+
+ The `BINFO_BASETYPES' is a `TREE_VEC' (*note Containers::). Base
+types appear in left-to-right order in this vector. You can tell
+whether or `public', `protected', or `private' inheritance was used by
+using the `TREE_VIA_PUBLIC', `TREE_VIA_PROTECTED', and
+`TREE_VIA_PRIVATE' macros. Each of these macros takes a `BINFO' and is
+true if and only if the indicated kind of inheritance was used. If
+`TREE_VIA_VIRTUAL' holds of a binfo, then its `BINFO_TYPE' was
+inherited from virtually.
+
+ The following macros can be used on a tree node representing a
+class-type.
+
+`LOCAL_CLASS_P'
+ This predicate holds if the class is local class _i.e._ declared
+ inside a function body.
+
+`TYPE_POLYMORPHIC_P'
+ This predicate holds if the class has at least one virtual function
+ (declared or inherited).
+
+`TYPE_HAS_DEFAULT_CONSTRUCTOR'
+ This predicate holds whenever its argument represents a class-type
+ with default constructor.
+
+`CLASSTYPE_HAS_MUTABLE'
+
+`TYPE_HAS_MUTABLE_P'
+ These predicates hold for a class-type having a mutable data
+ member.
+
+`CLASSTYPE_NON_POD_P'
+ This predicate holds only for class-types that are not PODs.
+
+`TYPE_HAS_NEW_OPERATOR'
+ This predicate holds for a class-type that defines `operator new'.
+
+`TYPE_HAS_ARRAY_NEW_OPERATOR'
+ This predicate holds for a class-type for which `operator new[]'
+ is defined.
+
+`TYPE_OVERLOADS_CALL_EXPR'
+ This predicate holds for class-type for which the function call
+ `operator()' is overloaded.
+
+`TYPE_OVERLOADS_ARRAY_REF'
+ This predicate holds for a class-type that overloads `operator[]'
+
+`TYPE_OVERLOADS_ARROW'
+ This predicate holds for a class-type for which `operator->' is
+ overloaded.
+
+
+\1f
+File: gccint.info, Node: Declarations, Next: Attributes, Prev: Functions, Up: Trees
+
+7.5 Declarations
+================
+
+This section covers the various kinds of declarations that appear in the
+internal representation, except for declarations of functions
+(represented by `FUNCTION_DECL' nodes), which are described in *note
+Functions::.
+
+ Some macros can be used with any kind of declaration. These include:
+`DECL_NAME'
+ This macro returns an `IDENTIFIER_NODE' giving the name of the
+ entity.
+
+`TREE_TYPE'
+ This macro returns the type of the entity declared.
+
+`DECL_SOURCE_FILE'
+ This macro returns the name of the file in which the entity was
+ declared, as a `char*'. For an entity declared implicitly by the
+ compiler (like `__builtin_memcpy'), this will be the string
+ `"<internal>"'.
+
+`DECL_SOURCE_LINE'
+ This macro returns the line number at which the entity was
+ declared, as an `int'.
+
+`DECL_ARTIFICIAL'
+ This predicate holds if the declaration was implicitly generated
+ by the compiler. For example, this predicate will hold of an
+ implicitly declared member function, or of the `TYPE_DECL'
+ implicitly generated for a class type. Recall that in C++ code
+ like:
+ struct S {};
+ is roughly equivalent to C code like:
+ struct S {};
+ typedef struct S S;
+ The implicitly generated `typedef' declaration is represented by a
+ `TYPE_DECL' for which `DECL_ARTIFICIAL' holds.
+
+`DECL_NAMESPACE_SCOPE_P'
+ This predicate holds if the entity was declared at a namespace
+ scope.
+
+`DECL_CLASS_SCOPE_P'
+ This predicate holds if the entity was declared at a class scope.
+
+`DECL_FUNCTION_SCOPE_P'
+ This predicate holds if the entity was declared inside a function
+ body.
+
+
+ The various kinds of declarations include:
+`LABEL_DECL'
+ These nodes are used to represent labels in function bodies. For
+ more information, see *note Functions::. These nodes only appear
+ in block scopes.
+
+`CONST_DECL'
+ These nodes are used to represent enumeration constants. The
+ value of the constant is given by `DECL_INITIAL' which will be an
+ `INTEGER_CST' with the same type as the `TREE_TYPE' of the
+ `CONST_DECL', i.e., an `ENUMERAL_TYPE'.
+
+`RESULT_DECL'
+ These nodes represent the value returned by a function. When a
+ value is assigned to a `RESULT_DECL', that indicates that the
+ value should be returned, via bitwise copy, by the function. You
+ can use `DECL_SIZE' and `DECL_ALIGN' on a `RESULT_DECL', just as
+ with a `VAR_DECL'.
+
+`TYPE_DECL'
+ These nodes represent `typedef' declarations. The `TREE_TYPE' is
+ the type declared to have the name given by `DECL_NAME'. In some
+ cases, there is no associated name.
+
+`VAR_DECL'
+ These nodes represent variables with namespace or block scope, as
+ well as static data members. The `DECL_SIZE' and `DECL_ALIGN' are
+ analogous to `TYPE_SIZE' and `TYPE_ALIGN'. For a declaration, you
+ should always use the `DECL_SIZE' and `DECL_ALIGN' rather than the
+ `TYPE_SIZE' and `TYPE_ALIGN' given by the `TREE_TYPE', since
+ special attributes may have been applied to the variable to give
+ it a particular size and alignment. You may use the predicates
+ `DECL_THIS_STATIC' or `DECL_THIS_EXTERN' to test whether the
+ storage class specifiers `static' or `extern' were used to declare
+ a variable.
+
+ If this variable is initialized (but does not require a
+ constructor), the `DECL_INITIAL' will be an expression for the
+ initializer. The initializer should be evaluated, and a bitwise
+ copy into the variable performed. If the `DECL_INITIAL' is the
+ `error_mark_node', there is an initializer, but it is given by an
+ explicit statement later in the code; no bitwise copy is required.
+
+ GCC provides an extension that allows either automatic variables,
+ or global variables, to be placed in particular registers. This
+ extension is being used for a particular `VAR_DECL' if
+ `DECL_REGISTER' holds for the `VAR_DECL', and if
+ `DECL_ASSEMBLER_NAME' is not equal to `DECL_NAME'. In that case,
+ `DECL_ASSEMBLER_NAME' is the name of the register into which the
+ variable will be placed.
+
+`PARM_DECL'
+ Used to represent a parameter to a function. Treat these nodes
+ similarly to `VAR_DECL' nodes. These nodes only appear in the
+ `DECL_ARGUMENTS' for a `FUNCTION_DECL'.
+
+ The `DECL_ARG_TYPE' for a `PARM_DECL' is the type that will
+ actually be used when a value is passed to this function. It may
+ be a wider type than the `TREE_TYPE' of the parameter; for
+ example, the ordinary type might be `short' while the
+ `DECL_ARG_TYPE' is `int'.
+
+`FIELD_DECL'
+ These nodes represent non-static data members. The `DECL_SIZE' and
+ `DECL_ALIGN' behave as for `VAR_DECL' nodes. The
+ `DECL_FIELD_BITPOS' gives the first bit used for this field, as an
+ `INTEGER_CST'. These values are indexed from zero, where zero
+ indicates the first bit in the object.
+
+ If `DECL_C_BIT_FIELD' holds, this field is a bit-field.
+
+`NAMESPACE_DECL'
+ *Note Namespaces::.
+
+`TEMPLATE_DECL'
+ These nodes are used to represent class, function, and variable
+ (static data member) templates. The
+ `DECL_TEMPLATE_SPECIALIZATIONS' are a `TREE_LIST'. The
+ `TREE_VALUE' of each node in the list is a `TEMPLATE_DECL's or
+ `FUNCTION_DECL's representing specializations (including
+ instantiations) of this template. Back ends can safely ignore
+ `TEMPLATE_DECL's, but should examine `FUNCTION_DECL' nodes on the
+ specializations list just as they would ordinary `FUNCTION_DECL'
+ nodes.
+
+ For a class template, the `DECL_TEMPLATE_INSTANTIATIONS' list
+ contains the instantiations. The `TREE_VALUE' of each node is an
+ instantiation of the class. The `DECL_TEMPLATE_SPECIALIZATIONS'
+ contains partial specializations of the class.
+
+`USING_DECL'
+ Back ends can safely ignore these nodes.
+
+
+\1f
+File: gccint.info, Node: Functions, Next: Declarations, Prev: Scopes, Up: Trees
+
+7.6 Functions
+=============
+
+A function is represented by a `FUNCTION_DECL' node. A set of
+overloaded functions is sometimes represented by a `OVERLOAD' node.
+
+ An `OVERLOAD' node is not a declaration, so none of the `DECL_'
+macros should be used on an `OVERLOAD'. An `OVERLOAD' node is similar
+to a `TREE_LIST'. Use `OVL_CURRENT' to get the function associated
+with an `OVERLOAD' node; use `OVL_NEXT' to get the next `OVERLOAD' node
+in the list of overloaded functions. The macros `OVL_CURRENT' and
+`OVL_NEXT' are actually polymorphic; you can use them to work with
+`FUNCTION_DECL' nodes as well as with overloads. In the case of a
+`FUNCTION_DECL', `OVL_CURRENT' will always return the function itself,
+and `OVL_NEXT' will always be `NULL_TREE'.
+
+ To determine the scope of a function, you can use the
+`DECL_REAL_CONTEXT' macro. This macro will return the class (either a
+`RECORD_TYPE' or a `UNION_TYPE') or namespace (a `NAMESPACE_DECL') of
+which the function is a member. For a virtual function, this macro
+returns the class in which the function was actually defined, not the
+base class in which the virtual declaration occurred. If a friend
+function is defined in a class scope, the `DECL_CLASS_CONTEXT' macro
+can be used to determine the class in which it was defined. For
+example, in
+ class C { friend void f() {} };
+ the `DECL_REAL_CONTEXT' for `f' will be the `global_namespace', but
+the `DECL_CLASS_CONTEXT' will be the `RECORD_TYPE' for `C'.
+
+ The `DECL_REAL_CONTEXT' and `DECL_CLASS_CONTEXT' are not available
+in C; instead you should simply use `DECL_CONTEXT'. In C, the
+`DECL_CONTEXT' for a function maybe another function. This
+representation indicates that the GNU nested function extension is in
+use. For details on the semantics of nested functions, see the GCC
+Manual. The nested function can refer to local variables in its
+containing function. Such references are not explicitly marked in the
+tree structure; back ends must look at the `DECL_CONTEXT' for the
+referenced `VAR_DECL'. If the `DECL_CONTEXT' for the referenced
+`VAR_DECL' is not the same as the function currently being processed,
+and neither `DECL_EXTERNAL' nor `DECL_STATIC' hold, then the reference
+is to a local variable in a containing function, and the back end must
+take appropriate action.
+
+* Menu:
+
+* Function Basics:: Function names, linkage, and so forth.
+* Function Bodies:: The statements that make up a function body.
+
+\1f
+File: gccint.info, Node: Function Basics, Next: Function Bodies, Up: Functions
+
+7.6.1 Function Basics
+---------------------
+
+The following macros and functions can be used on a `FUNCTION_DECL':
+`DECL_MAIN_P'
+ This predicate holds for a function that is the program entry point
+ `::code'.
+
+`DECL_NAME'
+ This macro returns the unqualified name of the function, as an
+ `IDENTIFIER_NODE'. For an instantiation of a function template,
+ the `DECL_NAME' is the unqualified name of the template, not
+ something like `f<int>'. The value of `DECL_NAME' is undefined
+ when used on a constructor, destructor, overloaded operator, or
+ type-conversion operator, or any function that is implicitly
+ generated by the compiler. See below for macros that can be used
+ to distinguish these cases.
+
+`DECL_ASSEMBLER_NAME'
+ This macro returns the mangled name of the function, also an
+ `IDENTIFIER_NODE'. This name does not contain leading underscores
+ on systems that prefix all identifiers with underscores. The
+ mangled name is computed in the same way on all platforms; if
+ special processing is required to deal with the object file format
+ used on a particular platform, it is the responsibility of the
+ back end to perform those modifications. (Of course, the back end
+ should not modify `DECL_ASSEMBLER_NAME' itself.)
+
+`DECL_EXTERNAL'
+ This predicate holds if the function is undefined.
+
+`TREE_PUBLIC'
+ This predicate holds if the function has external linkage.
+
+`DECL_LOCAL_FUNCTION_P'
+ This predicate holds if the function was declared at block scope,
+ even though it has a global scope.
+
+`DECL_ANTICIPATED'
+ This predicate holds if the function is a built-in function but its
+ prototype is not yet explicitly declared.
+
+`DECL_EXTERN_C_FUNCTION_P'
+ This predicate holds if the function is declared as an ``extern
+ "C"'' function.
+
+`DECL_LINKONCE_P'
+ This macro holds if multiple copies of this function may be
+ emitted in various translation units. It is the responsibility of
+ the linker to merge the various copies. Template instantiations
+ are the most common example of functions for which
+ `DECL_LINKONCE_P' holds; G++ instantiates needed templates in all
+ translation units which require them, and then relies on the
+ linker to remove duplicate instantiations.
+
+ FIXME: This macro is not yet implemented.
+
+`DECL_FUNCTION_MEMBER_P'
+ This macro holds if the function is a member of a class, rather
+ than a member of a namespace.
+
+`DECL_STATIC_FUNCTION_P'
+ This predicate holds if the function a static member function.
+
+`DECL_NONSTATIC_MEMBER_FUNCTION_P'
+ This macro holds for a non-static member function.
+
+`DECL_CONST_MEMFUNC_P'
+ This predicate holds for a `const'-member function.
+
+`DECL_VOLATILE_MEMFUNC_P'
+ This predicate holds for a `volatile'-member function.
+
+`DECL_CONSTRUCTOR_P'
+ This macro holds if the function is a constructor.
+
+`DECL_NONCONVERTING_P'
+ This predicate holds if the constructor is a non-converting
+ constructor.
+
+`DECL_COMPLETE_CONSTRUCTOR_P'
+ This predicate holds for a function which is a constructor for an
+ object of a complete type.
+
+`DECL_BASE_CONSTRUCTOR_P'
+ This predicate holds for a function which is a constructor for a
+ base class sub-object.
+
+`DECL_COPY_CONSTRUCTOR_P'
+ This predicate holds for a function which is a copy-constructor.
+
+`DECL_DESTRUCTOR_P'
+ This macro holds if the function is a destructor.
+
+`DECL_COMPLETE_DESTRUCTOR_P'
+ This predicate holds if the function is the destructor for an
+ object a complete type.
+
+`DECL_OVERLOADED_OPERATOR_P'
+ This macro holds if the function is an overloaded operator.
+
+`DECL_CONV_FN_P'
+ This macro holds if the function is a type-conversion operator.
+
+`DECL_GLOBAL_CTOR_P'
+ This predicate holds if the function is a file-scope initialization
+ function.
+
+`DECL_GLOBAL_DTOR_P'
+ This predicate holds if the function is a file-scope finalization
+ function.
+
+`DECL_THUNK_P'
+ This predicate holds if the function is a thunk.
+
+ These functions represent stub code that adjusts the `this' pointer
+ and then jumps to another function. When the jumped-to function
+ returns, control is transferred directly to the caller, without
+ returning to the thunk. The first parameter to the thunk is
+ always the `this' pointer; the thunk should add `THUNK_DELTA' to
+ this value. (The `THUNK_DELTA' is an `int', not an `INTEGER_CST'.)
+
+ Then, if `THUNK_VCALL_OFFSET' (an `INTEGER_CST') is nonzero the
+ adjusted `this' pointer must be adjusted again. The complete
+ calculation is given by the following pseudo-code:
+
+ this += THUNK_DELTA
+ if (THUNK_VCALL_OFFSET)
+ this += (*((ptrdiff_t **) this))[THUNK_VCALL_OFFSET]
+
+ Finally, the thunk should jump to the location given by
+ `DECL_INITIAL'; this will always be an expression for the address
+ of a function.
+
+`DECL_NON_THUNK_FUNCTION_P'
+ This predicate holds if the function is _not_ a thunk function.
+
+`GLOBAL_INIT_PRIORITY'
+ If either `DECL_GLOBAL_CTOR_P' or `DECL_GLOBAL_DTOR_P' holds, then
+ this gives the initialization priority for the function. The
+ linker will arrange that all functions for which
+ `DECL_GLOBAL_CTOR_P' holds are run in increasing order of priority
+ before `main' is called. When the program exits, all functions for
+ which `DECL_GLOBAL_DTOR_P' holds are run in the reverse order.
+
+`DECL_ARTIFICIAL'
+ This macro holds if the function was implicitly generated by the
+ compiler, rather than explicitly declared. In addition to
+ implicitly generated class member functions, this macro holds for
+ the special functions created to implement static initialization
+ and destruction, to compute run-time type information, and so
+ forth.
+
+`DECL_ARGUMENTS'
+ This macro returns the `PARM_DECL' for the first argument to the
+ function. Subsequent `PARM_DECL' nodes can be obtained by
+ following the `TREE_CHAIN' links.
+
+`DECL_RESULT'
+ This macro returns the `RESULT_DECL' for the function.
+
+`TREE_TYPE'
+ This macro returns the `FUNCTION_TYPE' or `METHOD_TYPE' for the
+ function.
+
+`TYPE_RAISES_EXCEPTIONS'
+ This macro returns the list of exceptions that a (member-)function
+ can raise. The returned list, if non `NULL', is comprised of nodes
+ whose `TREE_VALUE' represents a type.
+
+`TYPE_NOTHROW_P'
+ This predicate holds when the exception-specification of its
+ arguments if of the form ``()''.
+
+`DECL_ARRAY_DELETE_OPERATOR_P'
+ This predicate holds if the function an overloaded `operator
+ delete[]'.
+
+
+\1f
+File: gccint.info, Node: Function Bodies, Prev: Function Basics, Up: Functions
+
+7.6.2 Function Bodies
+---------------------
+
+A function that has a definition in the current translation unit will
+have a non-`NULL' `DECL_INITIAL'. However, back ends should not make
+use of the particular value given by `DECL_INITIAL'.
+
+ The `DECL_SAVED_TREE' macro will give the complete body of the
+function. This node will usually be a `COMPOUND_STMT' representing the
+outermost block of the function, but it may also be a `TRY_BLOCK', a
+`RETURN_INIT', or any other valid statement.
+
+7.6.2.1 Statements
+..................
+
+There are tree nodes corresponding to all of the source-level statement
+constructs. These are enumerated here, together with a list of the
+various macros that can be used to obtain information about them. There
+are a few macros that can be used with all statements:
+
+`STMT_LINENO'
+ This macro returns the line number for the statement. If the
+ statement spans multiple lines, this value will be the number of
+ the first line on which the statement occurs. Although we mention
+ `CASE_LABEL' below as if it were a statement, they do not allow
+ the use of `STMT_LINENO'. There is no way to obtain the line
+ number for a `CASE_LABEL'.
+
+ Statements do not contain information about the file from which
+ they came; that information is implicit in the `FUNCTION_DECL'
+ from which the statements originate.
+
+`STMT_IS_FULL_EXPR_P'
+ In C++, statements normally constitute "full expressions";
+ temporaries created during a statement are destroyed when the
+ statement is complete. However, G++ sometimes represents
+ expressions by statements; these statements will not have
+ `STMT_IS_FULL_EXPR_P' set. Temporaries created during such
+ statements should be destroyed when the innermost enclosing
+ statement with `STMT_IS_FULL_EXPR_P' set is exited.
+
+
+ Here is the list of the various statement nodes, and the macros used
+to access them. This documentation describes the use of these nodes in
+non-template functions (including instantiations of template functions).
+In template functions, the same nodes are used, but sometimes in
+slightly different ways.
+
+ Many of the statements have substatements. For example, a `while'
+loop will have a body, which is itself a statement. If the substatement
+is `NULL_TREE', it is considered equivalent to a statement consisting
+of a single `;', i.e., an expression statement in which the expression
+has been omitted. A substatement may in fact be a list of statements,
+connected via their `TREE_CHAIN's. So, you should always process the
+statement tree by looping over substatements, like this:
+ void process_stmt (stmt)
+ tree stmt;
+ {
+ while (stmt)
+ {
+ switch (TREE_CODE (stmt))
+ {
+ case IF_STMT:
+ process_stmt (THEN_CLAUSE (stmt));
+ /* More processing here. */
+ break;
+
+ ...
+ }
+
+ stmt = TREE_CHAIN (stmt);
+ }
+ }
+ In other words, while the `then' clause of an `if' statement in C++
+can be only one statement (although that one statement may be a
+compound statement), the intermediate representation will sometimes use
+several statements chained together.
+
+`ASM_STMT'
+ Used to represent an inline assembly statement. For an inline
+ assembly statement like:
+ asm ("mov x, y");
+ The `ASM_STRING' macro will return a `STRING_CST' node for `"mov
+ x, y"'. If the original statement made use of the
+ extended-assembly syntax, then `ASM_OUTPUTS', `ASM_INPUTS', and
+ `ASM_CLOBBERS' will be the outputs, inputs, and clobbers for the
+ statement, represented as `STRING_CST' nodes. The
+ extended-assembly syntax looks like:
+ asm ("fsinx %1,%0" : "=f" (result) : "f" (angle));
+ The first string is the `ASM_STRING', containing the instruction
+ template. The next two strings are the output and inputs,
+ respectively; this statement has no clobbers. As this example
+ indicates, "plain" assembly statements are merely a special case
+ of extended assembly statements; they have no cv-qualifiers,
+ outputs, inputs, or clobbers. All of the strings will be
+ `NUL'-terminated, and will contain no embedded `NUL'-characters.
+
+ If the assembly statement is declared `volatile', or if the
+ statement was not an extended assembly statement, and is therefore
+ implicitly volatile, then the predicate `ASM_VOLATILE_P' will hold
+ of the `ASM_STMT'.
+
+`BREAK_STMT'
+ Used to represent a `break' statement. There are no additional
+ fields.
+
+`CASE_LABEL'
+ Use to represent a `case' label, range of `case' labels, or a
+ `default' label. If `CASE_LOW' is `NULL_TREE', then this is a
+ `default' label. Otherwise, if `CASE_HIGH' is `NULL_TREE', then
+ this is an ordinary `case' label. In this case, `CASE_LOW' is an
+ expression giving the value of the label. Both `CASE_LOW' and
+ `CASE_HIGH' are `INTEGER_CST' nodes. These values will have the
+ same type as the condition expression in the switch statement.
+
+ Otherwise, if both `CASE_LOW' and `CASE_HIGH' are defined, the
+ statement is a range of case labels. Such statements originate
+ with the extension that allows users to write things of the form:
+ case 2 ... 5:
+ The first value will be `CASE_LOW', while the second will be
+ `CASE_HIGH'.
+
+`CLEANUP_STMT'
+ Used to represent an action that should take place upon exit from
+ the enclosing scope. Typically, these actions are calls to
+ destructors for local objects, but back ends cannot rely on this
+ fact. If these nodes are in fact representing such destructors,
+ `CLEANUP_DECL' will be the `VAR_DECL' destroyed. Otherwise,
+ `CLEANUP_DECL' will be `NULL_TREE'. In any case, the
+ `CLEANUP_EXPR' is the expression to execute. The cleanups
+ executed on exit from a scope should be run in the reverse order
+ of the order in which the associated `CLEANUP_STMT's were
+ encountered.
+
+`COMPOUND_STMT'
+ Used to represent a brace-enclosed block. The first substatement
+ is given by `COMPOUND_BODY'. Subsequent substatements are found by
+ following the `TREE_CHAIN' link from one substatement to the next.
+ The `COMPOUND_BODY' will be `NULL_TREE' if there are no
+ substatements.
+
+`CONTINUE_STMT'
+ Used to represent a `continue' statement. There are no additional
+ fields.
+
+`CTOR_STMT'
+ Used to mark the beginning (if `CTOR_BEGIN_P' holds) or end (if
+ `CTOR_END_P' holds of the main body of a constructor. See also
+ `SUBOBJECT' for more information on how to use these nodes.
+
+`DECL_STMT'
+ Used to represent a local declaration. The `DECL_STMT_DECL' macro
+ can be used to obtain the entity declared. This declaration may
+ be a `LABEL_DECL', indicating that the label declared is a local
+ label. (As an extension, GCC allows the declaration of labels
+ with scope.) In C, this declaration may be a `FUNCTION_DECL',
+ indicating the use of the GCC nested function extension. For more
+ information, *note Functions::.
+
+`DO_STMT'
+ Used to represent a `do' loop. The body of the loop is given by
+ `DO_BODY' while the termination condition for the loop is given by
+ `DO_COND'. The condition for a `do'-statement is always an
+ expression.
+
+`EMPTY_CLASS_EXPR'
+ Used to represent a temporary object of a class with no data whose
+ address is never taken. (All such objects are interchangeable.)
+ The `TREE_TYPE' represents the type of the object.
+
+`EXPR_STMT'
+ Used to represent an expression statement. Use `EXPR_STMT_EXPR' to
+ obtain the expression.
+
+`FILE_STMT'
+ Used to record a change in filename within the body of a function.
+ Use `FILE_STMT_FILENAME' to obtain the new filename.
+
+`FOR_STMT'
+ Used to represent a `for' statement. The `FOR_INIT_STMT' is the
+ initialization statement for the loop. The `FOR_COND' is the
+ termination condition. The `FOR_EXPR' is the expression executed
+ right before the `FOR_COND' on each loop iteration; often, this
+ expression increments a counter. The body of the loop is given by
+ `FOR_BODY'. Note that `FOR_INIT_STMT' and `FOR_BODY' return
+ statements, while `FOR_COND' and `FOR_EXPR' return expressions.
+
+`GOTO_STMT'
+ Used to represent a `goto' statement. The `GOTO_DESTINATION' will
+ usually be a `LABEL_DECL'. However, if the "computed goto"
+ extension has been used, the `GOTO_DESTINATION' will be an
+ arbitrary expression indicating the destination. This expression
+ will always have pointer type. Additionally the `GOTO_FAKE_P'
+ flag is set whenever the goto statement does not come from source
+ code, but it is generated implicitly by the compiler. This is
+ used for branch prediction.
+
+`HANDLER'
+ Used to represent a C++ `catch' block. The `HANDLER_TYPE' is the
+ type of exception that will be caught by this handler; it is equal
+ (by pointer equality) to `CATCH_ALL_TYPE' if this handler is for
+ all types. `HANDLER_PARMS' is the `DECL_STMT' for the catch
+ parameter, and `HANDLER_BODY' is the `COMPOUND_STMT' for the block
+ itself.
+
+`IF_STMT'
+ Used to represent an `if' statement. The `IF_COND' is the
+ expression.
+
+ If the condition is a `TREE_LIST', then the `TREE_PURPOSE' is a
+ statement (usually a `DECL_STMT'). Each time the condition is
+ evaluated, the statement should be executed. Then, the
+ `TREE_VALUE' should be used as the conditional expression itself.
+ This representation is used to handle C++ code like this:
+
+ if (int i = 7) ...
+
+ where there is a new local variable (or variables) declared within
+ the condition.
+
+ The `THEN_CLAUSE' represents the statement given by the `then'
+ condition, while the `ELSE_CLAUSE' represents the statement given
+ by the `else' condition.
+
+`LABEL_STMT'
+ Used to represent a label. The `LABEL_DECL' declared by this
+ statement can be obtained with the `LABEL_STMT_LABEL' macro. The
+ `IDENTIFIER_NODE' giving the name of the label can be obtained from
+ the `LABEL_DECL' with `DECL_NAME'.
+
+`RETURN_INIT'
+ If the function uses the G++ "named return value" extension,
+ meaning that the function has been defined like:
+ S f(int) return s {...}
+ then there will be a `RETURN_INIT'. There is never a named
+ returned value for a constructor. The first argument to the
+ `RETURN_INIT' is the name of the object returned; the second
+ argument is the initializer for the object. The object is
+ initialized when the `RETURN_INIT' is encountered. The object
+ referred to is the actual object returned; this extension is a
+ manual way of doing the "return-value optimization." Therefore,
+ the object must actually be constructed in the place where the
+ object will be returned.
+
+`RETURN_STMT'
+ Used to represent a `return' statement. The `RETURN_EXPR' is the
+ expression returned; it will be `NULL_TREE' if the statement was
+ just
+ return;
+
+`SCOPE_STMT'
+ A scope-statement represents the beginning or end of a scope. If
+ `SCOPE_BEGIN_P' holds, this statement represents the beginning of a
+ scope; if `SCOPE_END_P' holds this statement represents the end of
+ a scope. On exit from a scope, all cleanups from `CLEANUP_STMT's
+ occurring in the scope must be run, in reverse order to the order
+ in which they were encountered. If `SCOPE_NULLIFIED_P' or
+ `SCOPE_NO_CLEANUPS_P' holds of the scope, back ends should behave
+ as if the `SCOPE_STMT' were not present at all.
+
+`SUBOBJECT'
+ In a constructor, these nodes are used to mark the point at which a
+ subobject of `this' is fully constructed. If, after this point, an
+ exception is thrown before a `CTOR_STMT' with `CTOR_END_P' set is
+ encountered, the `SUBOBJECT_CLEANUP' must be executed. The
+ cleanups must be executed in the reverse order in which they
+ appear.
+
+`SWITCH_STMT'
+ Used to represent a `switch' statement. The `SWITCH_COND' is the
+ expression on which the switch is occurring. See the documentation
+ for an `IF_STMT' for more information on the representation used
+ for the condition. The `SWITCH_BODY' is the body of the switch
+ statement. The `SWITCH_TYPE' is the original type of switch
+ expression as given in the source, before any compiler conversions.
+
+`TRY_BLOCK'
+ Used to represent a `try' block. The body of the try block is
+ given by `TRY_STMTS'. Each of the catch blocks is a `HANDLER'
+ node. The first handler is given by `TRY_HANDLERS'. Subsequent
+ handlers are obtained by following the `TREE_CHAIN' link from one
+ handler to the next. The body of the handler is given by
+ `HANDLER_BODY'.
+
+ If `CLEANUP_P' holds of the `TRY_BLOCK', then the `TRY_HANDLERS'
+ will not be a `HANDLER' node. Instead, it will be an expression
+ that should be executed if an exception is thrown in the try
+ block. It must rethrow the exception after executing that code.
+ And, if an exception is thrown while the expression is executing,
+ `terminate' must be called.
+
+`USING_STMT'
+ Used to represent a `using' directive. The namespace is given by
+ `USING_STMT_NAMESPACE', which will be a NAMESPACE_DECL. This node
+ is needed inside template functions, to implement using directives
+ during instantiation.
+
+`WHILE_STMT'
+ Used to represent a `while' loop. The `WHILE_COND' is the
+ termination condition for the loop. See the documentation for an
+ `IF_STMT' for more information on the representation used for the
+ condition.
+
+ The `WHILE_BODY' is the body of the loop.
+
+
+\1f
+File: gccint.info, Node: Attributes, Next: Expression trees, Prev: Declarations, Up: Trees
+
+7.7 Attributes in trees
+=======================
+
+Attributes, as specified using the `__attribute__' keyword, are
+represented internally as a `TREE_LIST'. The `TREE_PURPOSE' is the
+name of the attribute, as an `IDENTIFIER_NODE'. The `TREE_VALUE' is a
+`TREE_LIST' of the arguments of the attribute, if any, or `NULL_TREE'
+if there are no arguments; the arguments are stored as the `TREE_VALUE'
+of successive entries in the list, and may be identifiers or
+expressions. The `TREE_CHAIN' of the attribute is the next attribute
+in a list of attributes applying to the same declaration or type, or
+`NULL_TREE' if there are no further attributes in the list.
+
+ Attributes may be attached to declarations and to types; these
+attributes may be accessed with the following macros. All attributes
+are stored in this way, and many also cause other changes to the
+declaration or type or to other internal compiler data structures.
+
+ -- Tree Macro: tree DECL_ATTRIBUTES (tree DECL)
+ This macro returns the attributes on the declaration DECL.
+
+ -- Tree Macro: tree TYPE_ATTRIBUTES (tree TYPE)
+ This macro returns the attributes on the type TYPE.
+
+\1f
+File: gccint.info, Node: Expression trees, Prev: Attributes, Up: Trees
+
+7.8 Expressions
+===============
+
+The internal representation for expressions is for the most part quite
+straightforward. However, there are a few facts that one must bear in
+mind. In particular, the expression "tree" is actually a directed
+acyclic graph. (For example there may be many references to the integer
+constant zero throughout the source program; many of these will be
+represented by the same expression node.) You should not rely on
+certain kinds of node being shared, nor should rely on certain kinds of
+nodes being unshared.
+
+ The following macros can be used with all expression nodes:
+
+`TREE_TYPE'
+ Returns the type of the expression. This value may not be
+ precisely the same type that would be given the expression in the
+ original program.
+
+ In what follows, some nodes that one might expect to always have type
+`bool' are documented to have either integral or boolean type. At some
+point in the future, the C front end may also make use of this same
+intermediate representation, and at this point these nodes will
+certainly have integral type. The previous sentence is not meant to
+imply that the C++ front end does not or will not give these nodes
+integral type.
+
+ Below, we list the various kinds of expression nodes. Except where
+noted otherwise, the operands to an expression are accessed using the
+`TREE_OPERAND' macro. For example, to access the first operand to a
+binary plus expression `expr', use:
+
+ TREE_OPERAND (expr, 0)
+ As this example indicates, the operands are zero-indexed.
+
+ The table below begins with constants, moves on to unary expressions,
+then proceeds to binary expressions, and concludes with various other
+kinds of expressions:
+
+`INTEGER_CST'
+ These nodes represent integer constants. Note that the type of
+ these constants is obtained with `TREE_TYPE'; they are not always
+ of type `int'. In particular, `char' constants are represented
+ with `INTEGER_CST' nodes. The value of the integer constant `e' is
+ given by
+ ((TREE_INT_CST_HIGH (e) << HOST_BITS_PER_WIDE_INT)
+ + TREE_INST_CST_LOW (e))
+ HOST_BITS_PER_WIDE_INT is at least thirty-two on all platforms.
+ Both `TREE_INT_CST_HIGH' and `TREE_INT_CST_LOW' return a
+ `HOST_WIDE_INT'. The value of an `INTEGER_CST' is interpreted as
+ a signed or unsigned quantity depending on the type of the
+ constant. In general, the expression given above will overflow,
+ so it should not be used to calculate the value of the constant.
+
+ The variable `integer_zero_node' is an integer constant with value
+ zero. Similarly, `integer_one_node' is an integer constant with
+ value one. The `size_zero_node' and `size_one_node' variables are
+ analogous, but have type `size_t' rather than `int'.
+
+ The function `tree_int_cst_lt' is a predicate which holds if its
+ first argument is less than its second. Both constants are
+ assumed to have the same signedness (i.e., either both should be
+ signed or both should be unsigned.) The full width of the
+ constant is used when doing the comparison; the usual rules about
+ promotions and conversions are ignored. Similarly,
+ `tree_int_cst_equal' holds if the two constants are equal. The
+ `tree_int_cst_sgn' function returns the sign of a constant. The
+ value is `1', `0', or `-1' according on whether the constant is
+ greater than, equal to, or less than zero. Again, the signedness
+ of the constant's type is taken into account; an unsigned constant
+ is never less than zero, no matter what its bit-pattern.
+
+`REAL_CST'
+ FIXME: Talk about how to obtain representations of this constant,
+ do comparisons, and so forth.
+
+`COMPLEX_CST'
+ These nodes are used to represent complex number constants, that
+ is a `__complex__' whose parts are constant nodes. The
+ `TREE_REALPART' and `TREE_IMAGPART' return the real and the
+ imaginary parts respectively.
+
+`VECTOR_CST'
+ These nodes are used to represent vector constants, whose parts are
+ constant nodes. Each individual constant node is either an
+ integer or a double constant node. The first operand is a
+ `TREE_LIST' of the constant nodes and is accessed through
+ `TREE_VECTOR_CST_ELTS'.
+
+`STRING_CST'
+ These nodes represent string-constants. The `TREE_STRING_LENGTH'
+ returns the length of the string, as an `int'. The
+ `TREE_STRING_POINTER' is a `char*' containing the string itself.
+ The string may not be `NUL'-terminated, and it may contain
+ embedded `NUL' characters. Therefore, the `TREE_STRING_LENGTH'
+ includes the trailing `NUL' if it is present.
+
+ For wide string constants, the `TREE_STRING_LENGTH' is the number
+ of bytes in the string, and the `TREE_STRING_POINTER' points to an
+ array of the bytes of the string, as represented on the target
+ system (that is, as integers in the target endianness). Wide and
+ non-wide string constants are distinguished only by the `TREE_TYPE'
+ of the `STRING_CST'.
+
+ FIXME: The formats of string constants are not well-defined when
+ the target system bytes are not the same width as host system
+ bytes.
+
+`PTRMEM_CST'
+ These nodes are used to represent pointer-to-member constants. The
+ `PTRMEM_CST_CLASS' is the class type (either a `RECORD_TYPE' or
+ `UNION_TYPE' within which the pointer points), and the
+ `PTRMEM_CST_MEMBER' is the declaration for the pointed to object.
+ Note that the `DECL_CONTEXT' for the `PTRMEM_CST_MEMBER' is in
+ general different from the `PTRMEM_CST_CLASS'. For example, given:
+ struct B { int i; };
+ struct D : public B {};
+ int D::*dp = &D::i;
+ The `PTRMEM_CST_CLASS' for `&D::i' is `D', even though the
+ `DECL_CONTEXT' for the `PTRMEM_CST_MEMBER' is `B', since `B::i' is
+ a member of `B', not `D'.
+
+`VAR_DECL'
+ These nodes represent variables, including static data members.
+ For more information, *note Declarations::.
+
+`NEGATE_EXPR'
+ These nodes represent unary negation of the single operand, for
+ both integer and floating-point types. The type of negation can be
+ determined by looking at the type of the expression.
+
+`BIT_NOT_EXPR'
+ These nodes represent bitwise complement, and will always have
+ integral type. The only operand is the value to be complemented.
+
+`TRUTH_NOT_EXPR'
+ These nodes represent logical negation, and will always have
+ integral (or boolean) type. The operand is the value being
+ negated.
+
+`PREDECREMENT_EXPR'
+`PREINCREMENT_EXPR'
+`POSTDECREMENT_EXPR'
+`POSTINCREMENT_EXPR'
+ These nodes represent increment and decrement expressions. The
+ value of the single operand is computed, and the operand
+ incremented or decremented. In the case of `PREDECREMENT_EXPR' and
+ `PREINCREMENT_EXPR', the value of the expression is the value
+ resulting after the increment or decrement; in the case of
+ `POSTDECREMENT_EXPR' and `POSTINCREMENT_EXPR' is the value before
+ the increment or decrement occurs. The type of the operand, like
+ that of the result, will be either integral, boolean, or
+ floating-point.
+
+`ADDR_EXPR'
+ These nodes are used to represent the address of an object. (These
+ expressions will always have pointer or reference type.) The
+ operand may be another expression, or it may be a declaration.
+
+ As an extension, GCC allows users to take the address of a label.
+ In this case, the operand of the `ADDR_EXPR' will be a
+ `LABEL_DECL'. The type of such an expression is `void*'.
+
+ If the object addressed is not an lvalue, a temporary is created,
+ and the address of the temporary is used.
+
+`INDIRECT_REF'
+ These nodes are used to represent the object pointed to by a
+ pointer. The operand is the pointer being dereferenced; it will
+ always have pointer or reference type.
+
+`FIX_TRUNC_EXPR'
+ These nodes represent conversion of a floating-point value to an
+ integer. The single operand will have a floating-point type,
+ while the the complete expression will have an integral (or
+ boolean) type. The operand is rounded towards zero.
+
+`FLOAT_EXPR'
+ These nodes represent conversion of an integral (or boolean) value
+ to a floating-point value. The single operand will have integral
+ type, while the complete expression will have a floating-point
+ type.
+
+ FIXME: How is the operand supposed to be rounded? Is this
+ dependent on `-mieee'?
+
+`COMPLEX_EXPR'
+ These nodes are used to represent complex numbers constructed from
+ two expressions of the same (integer or real) type. The first
+ operand is the real part and the second operand is the imaginary
+ part.
+
+`CONJ_EXPR'
+ These nodes represent the conjugate of their operand.
+
+`REALPART_EXPR'
+
+`IMAGPART_EXPR'
+ These nodes represent respectively the real and the imaginary parts
+ of complex numbers (their sole argument).
+
+`NON_LVALUE_EXPR'
+ These nodes indicate that their one and only operand is not an
+ lvalue. A back end can treat these identically to the single
+ operand.
+
+`NOP_EXPR'
+ These nodes are used to represent conversions that do not require
+ any code-generation. For example, conversion of a `char*' to an
+ `int*' does not require any code be generated; such a conversion is
+ represented by a `NOP_EXPR'. The single operand is the expression
+ to be converted. The conversion from a pointer to a reference is
+ also represented with a `NOP_EXPR'.
+
+`CONVERT_EXPR'
+ These nodes are similar to `NOP_EXPR's, but are used in those
+ situations where code may need to be generated. For example, if an
+ `int*' is converted to an `int' code may need to be generated on
+ some platforms. These nodes are never used for C++-specific
+ conversions, like conversions between pointers to different
+ classes in an inheritance hierarchy. Any adjustments that need to
+ be made in such cases are always indicated explicitly. Similarly,
+ a user-defined conversion is never represented by a
+ `CONVERT_EXPR'; instead, the function calls are made explicit.
+
+`THROW_EXPR'
+ These nodes represent `throw' expressions. The single operand is
+ an expression for the code that should be executed to throw the
+ exception. However, there is one implicit action not represented
+ in that expression; namely the call to `__throw'. This function
+ takes no arguments. If `setjmp'/`longjmp' exceptions are used, the
+ function `__sjthrow' is called instead. The normal GCC back end
+ uses the function `emit_throw' to generate this code; you can
+ examine this function to see what needs to be done.
+
+`LSHIFT_EXPR'
+`RSHIFT_EXPR'
+ These nodes represent left and right shifts, respectively. The
+ first operand is the value to shift; it will always be of integral
+ type. The second operand is an expression for the number of bits
+ by which to shift. Right shift should be treated as arithmetic,
+ i.e., the high-order bits should be zero-filled when the
+ expression has unsigned type and filled with the sign bit when the
+ expression has signed type. Note that the result is undefined if
+ the second operand is larger than the first operand's type size.
+
+`BIT_IOR_EXPR'
+`BIT_XOR_EXPR'
+`BIT_AND_EXPR'
+ These nodes represent bitwise inclusive or, bitwise exclusive or,
+ and bitwise and, respectively. Both operands will always have
+ integral type.
+
+`TRUTH_ANDIF_EXPR'
+`TRUTH_ORIF_EXPR'
+ These nodes represent logical and and logical or, respectively.
+ These operators are not strict; i.e., the second operand is
+ evaluated only if the value of the expression is not determined by
+ evaluation of the first operand. The type of the operands, and
+ the result type, is always of boolean or integral type.
+
+`TRUTH_AND_EXPR'
+`TRUTH_OR_EXPR'
+`TRUTH_XOR_EXPR'
+ These nodes represent logical and, logical or, and logical
+ exclusive or. They are strict; both arguments are always
+ evaluated. There are no corresponding operators in C or C++, but
+ the front end will sometimes generate these expressions anyhow, if
+ it can tell that strictness does not matter.
+
+`PLUS_EXPR'
+`MINUS_EXPR'
+`MULT_EXPR'
+`TRUNC_DIV_EXPR'
+`TRUNC_MOD_EXPR'
+`RDIV_EXPR'
+ These nodes represent various binary arithmetic operations.
+ Respectively, these operations are addition, subtraction (of the
+ second operand from the first), multiplication, integer division,
+ integer remainder, and floating-point division. The operands to
+ the first three of these may have either integral or floating
+ type, but there will never be case in which one operand is of
+ floating type and the other is of integral type.
+
+ The result of a `TRUNC_DIV_EXPR' is always rounded towards zero.
+ The `TRUNC_MOD_EXPR' of two operands `a' and `b' is always `a -
+ a/b' where the division is as if computed by a `TRUNC_DIV_EXPR'.
+
+`ARRAY_REF'
+ These nodes represent array accesses. The first operand is the
+ array; the second is the index. To calculate the address of the
+ memory accessed, you must scale the index by the size of the type
+ of the array elements. The type of these expressions must be the
+ type of a component of the array.
+
+`ARRAY_RANGE_REF'
+ These nodes represent access to a range (or "slice") of an array.
+ The operands are the same as that for `ARRAY_REF' and have the same
+ meanings. The type of these expressions must be an array whose
+ component type is the same as that of the first operand. The
+ range of that array type determines the amount of data these
+ expressions access.
+
+`EXACT_DIV_EXPR'
+ Document.
+
+`LT_EXPR'
+`LE_EXPR'
+`GT_EXPR'
+`GE_EXPR'
+`EQ_EXPR'
+`NE_EXPR'
+ These nodes represent the less than, less than or equal to, greater
+ than, greater than or equal to, equal, and not equal comparison
+ operators. The first and second operand with either be both of
+ integral type or both of floating type. The result type of these
+ expressions will always be of integral or boolean type.
+
+`MODIFY_EXPR'
+ These nodes represent assignment. The left-hand side is the first
+ operand; the right-hand side is the second operand. The left-hand
+ side will be a `VAR_DECL', `INDIRECT_REF', `COMPONENT_REF', or
+ other lvalue.
+
+ These nodes are used to represent not only assignment with `=' but
+ also compound assignments (like `+='), by reduction to `='
+ assignment. In other words, the representation for `i += 3' looks
+ just like that for `i = i + 3'.
+
+`INIT_EXPR'
+ These nodes are just like `MODIFY_EXPR', but are used only when a
+ variable is initialized, rather than assigned to subsequently.
+
+`COMPONENT_REF'
+ These nodes represent non-static data member accesses. The first
+ operand is the object (rather than a pointer to it); the second
+ operand is the `FIELD_DECL' for the data member.
+
+`COMPOUND_EXPR'
+ These nodes represent comma-expressions. The first operand is an
+ expression whose value is computed and thrown away prior to the
+ evaluation of the second operand. The value of the entire
+ expression is the value of the second operand.
+
+`COND_EXPR'
+ These nodes represent `?:' expressions. The first operand is of
+ boolean or integral type. If it evaluates to a nonzero value, the
+ second operand should be evaluated, and returned as the value of
+ the expression. Otherwise, the third operand is evaluated, and
+ returned as the value of the expression. As a GNU extension, the
+ middle operand of the `?:' operator may be omitted in the source,
+ like this:
+
+ x ? : 3
+ which is equivalent to
+
+ x ? x : 3
+
+ assuming that `x' is an expression without side-effects. However,
+ in the case that the first operation causes side effects, the
+ side-effects occur only once. Consumers of the internal
+ representation do not need to worry about this oddity; the second
+ operand will be always be present in the internal representation.
+
+`CALL_EXPR'
+ These nodes are used to represent calls to functions, including
+ non-static member functions. The first operand is a pointer to the
+ function to call; it is always an expression whose type is a
+ `POINTER_TYPE'. The second argument is a `TREE_LIST'. The
+ arguments to the call appear left-to-right in the list. The
+ `TREE_VALUE' of each list node contains the expression
+ corresponding to that argument. (The value of `TREE_PURPOSE' for
+ these nodes is unspecified, and should be ignored.) For non-static
+ member functions, there will be an operand corresponding to the
+ `this' pointer. There will always be expressions corresponding to
+ all of the arguments, even if the function is declared with default
+ arguments and some arguments are not explicitly provided at the
+ call sites.
+
+`STMT_EXPR'
+ These nodes are used to represent GCC's statement-expression
+ extension. The statement-expression extension allows code like
+ this:
+ int f() { return ({ int j; j = 3; j + 7; }); }
+ In other words, an sequence of statements may occur where a single
+ expression would normally appear. The `STMT_EXPR' node represents
+ such an expression. The `STMT_EXPR_STMT' gives the statement
+ contained in the expression; this is always a `COMPOUND_STMT'. The
+ value of the expression is the value of the last sub-statement in
+ the `COMPOUND_STMT'. More precisely, the value is the value
+ computed by the last `EXPR_STMT' in the outermost scope of the
+ `COMPOUND_STMT'. For example, in:
+ ({ 3; })
+ the value is `3' while in:
+ ({ if (x) { 3; } })
+ (represented by a nested `COMPOUND_STMT'), there is no value. If
+ the `STMT_EXPR' does not yield a value, it's type will be `void'.
+
+`BIND_EXPR'
+ These nodes represent local blocks. The first operand is a list of
+ temporary variables, connected via their `TREE_CHAIN' field. These
+ will never require cleanups. The scope of these variables is just
+ the body of the `BIND_EXPR'. The body of the `BIND_EXPR' is the
+ second operand.
+
+`LOOP_EXPR'
+ These nodes represent "infinite" loops. The `LOOP_EXPR_BODY'
+ represents the body of the loop. It should be executed forever,
+ unless an `EXIT_EXPR' is encountered.
+
+`EXIT_EXPR'
+ These nodes represent conditional exits from the nearest enclosing
+ `LOOP_EXPR'. The single operand is the condition; if it is
+ nonzero, then the loop should be exited. An `EXIT_EXPR' will only
+ appear within a `LOOP_EXPR'.
+
+`CLEANUP_POINT_EXPR'
+ These nodes represent full-expressions. The single operand is an
+ expression to evaluate. Any destructor calls engendered by the
+ creation of temporaries during the evaluation of that expression
+ should be performed immediately after the expression is evaluated.
+
+`CONSTRUCTOR'
+ These nodes represent the brace-enclosed initializers for a
+ structure or array. The first operand is reserved for use by the
+ back end. The second operand is a `TREE_LIST'. If the
+ `TREE_TYPE' of the `CONSTRUCTOR' is a `RECORD_TYPE' or
+ `UNION_TYPE', then the `TREE_PURPOSE' of each node in the
+ `TREE_LIST' will be a `FIELD_DECL' and the `TREE_VALUE' of each
+ node will be the expression used to initialize that field. You
+ should not depend on the fields appearing in any particular order,
+ nor should you assume that all fields will be represented.
+ Unrepresented fields may be assigned any value.
+
+ If the `TREE_TYPE' of the `CONSTRUCTOR' is an `ARRAY_TYPE', then
+ the `TREE_PURPOSE' of each element in the `TREE_LIST' will be an
+ `INTEGER_CST'. This constant indicates which element of the array
+ (indexed from zero) is being assigned to; again, the `TREE_VALUE'
+ is the corresponding initializer. If the `TREE_PURPOSE' is
+ `NULL_TREE', then the initializer is for the next available array
+ element.
+
+ Conceptually, before any initialization is done, the entire area of
+ storage is initialized to zero.
+
+`COMPOUND_LITERAL_EXPR'
+ These nodes represent ISO C99 compound literals. The
+ `COMPOUND_LITERAL_EXPR_DECL_STMT' is a `DECL_STMT' containing an
+ anonymous `VAR_DECL' for the unnamed object represented by the
+ compound literal; the `DECL_INITIAL' of that `VAR_DECL' is a
+ `CONSTRUCTOR' representing the brace-enclosed list of initializers
+ in the compound literal. That anonymous `VAR_DECL' can also be
+ accessed directly by the `COMPOUND_LITERAL_EXPR_DECL' macro.
+
+`SAVE_EXPR'
+ A `SAVE_EXPR' represents an expression (possibly involving
+ side-effects) that is used more than once. The side-effects should
+ occur only the first time the expression is evaluated. Subsequent
+ uses should just reuse the computed value. The first operand to
+ the `SAVE_EXPR' is the expression to evaluate. The side-effects
+ should be executed where the `SAVE_EXPR' is first encountered in a
+ depth-first preorder traversal of the expression tree.
+
+`TARGET_EXPR'
+ A `TARGET_EXPR' represents a temporary object. The first operand
+ is a `VAR_DECL' for the temporary variable. The second operand is
+ the initializer for the temporary. The initializer is evaluated,
+ and copied (bitwise) into the temporary.
+
+ Often, a `TARGET_EXPR' occurs on the right-hand side of an
+ assignment, or as the second operand to a comma-expression which is
+ itself the right-hand side of an assignment, etc. In this case,
+ we say that the `TARGET_EXPR' is "normal"; otherwise, we say it is
+ "orphaned". For a normal `TARGET_EXPR' the temporary variable
+ should be treated as an alias for the left-hand side of the
+ assignment, rather than as a new temporary variable.
+
+ The third operand to the `TARGET_EXPR', if present, is a
+ cleanup-expression (i.e., destructor call) for the temporary. If
+ this expression is orphaned, then this expression must be executed
+ when the statement containing this expression is complete. These
+ cleanups must always be executed in the order opposite to that in
+ which they were encountered. Note that if a temporary is created
+ on one branch of a conditional operator (i.e., in the second or
+ third operand to a `COND_EXPR'), the cleanup must be run only if
+ that branch is actually executed.
+
+ See `STMT_IS_FULL_EXPR_P' for more information about running these
+ cleanups.
+
+`AGGR_INIT_EXPR'
+ An `AGGR_INIT_EXPR' represents the initialization as the return
+ value of a function call, or as the result of a constructor. An
+ `AGGR_INIT_EXPR' will only appear as the second operand of a
+ `TARGET_EXPR'. The first operand to the `AGGR_INIT_EXPR' is the
+ address of a function to call, just as in a `CALL_EXPR'. The
+ second operand are the arguments to pass that function, as a
+ `TREE_LIST', again in a manner similar to that of a `CALL_EXPR'.
+ The value of the expression is that returned by the function.
+
+ If `AGGR_INIT_VIA_CTOR_P' holds of the `AGGR_INIT_EXPR', then the
+ initialization is via a constructor call. The address of the third
+ operand of the `AGGR_INIT_EXPR', which is always a `VAR_DECL', is
+ taken, and this value replaces the first argument in the argument
+ list. In this case, the value of the expression is the `VAR_DECL'
+ given by the third operand to the `AGGR_INIT_EXPR'; constructors do
+ not return a value.
+
+`VTABLE_REF'
+ A `VTABLE_REF' indicates that the interior expression computes a
+ value that is a vtable entry. It is used with `-fvtable-gc' to
+ track the reference through to front end to the middle end, at
+ which point we transform this to a `REG_VTABLE_REF' note, which
+ survives the balance of code generation.
+
+ The first operand is the expression that computes the vtable
+ reference. The second operand is the `VAR_DECL' of the vtable.
+ The third operand is an `INTEGER_CST' of the byte offset into the
+ vtable.
+
+
+\1f
+File: gccint.info, Node: RTL, Next: Machine Desc, Prev: Trees, Up: Top
+
+8 RTL Representation
+********************
+
+Most of the work of the compiler is done on an intermediate
+representation called register transfer language. In this language,
+the instructions to be output are described, pretty much one by one, in
+an algebraic form that describes what the instruction does.
+
+ RTL is inspired by Lisp lists. It has both an internal form, made
+up of structures that point at other structures, and a textual form
+that is used in the machine description and in printed debugging dumps.
+The textual form uses nested parentheses to indicate the pointers in
+the internal form.
+
+* Menu:
+
+* RTL Objects:: Expressions vs vectors vs strings vs integers.
+* RTL Classes:: Categories of RTL expression objects, and their structure.
+* Accessors:: Macros to access expression operands or vector elts.
+* Flags:: Other flags in an RTL expression.
+* Machine Modes:: Describing the size and format of a datum.
+* Constants:: Expressions with constant values.
+* Regs and Memory:: Expressions representing register contents or memory.
+* Arithmetic:: Expressions representing arithmetic on other expressions.
+* Comparisons:: Expressions representing comparison of expressions.
+* Bit-Fields:: Expressions representing bit-fields in memory or reg.
+* Vector Operations:: Expressions involving vector datatypes.
+* Conversions:: Extending, truncating, floating or fixing.
+* RTL Declarations:: Declaring volatility, constancy, etc.
+* Side Effects:: Expressions for storing in registers, etc.
+* Incdec:: Embedded side-effects for autoincrement addressing.
+* Assembler:: Representing `asm' with operands.
+* Insns:: Expression types for entire insns.
+* Calls:: RTL representation of function call insns.
+* Sharing:: Some expressions are unique; others *must* be copied.
+* Reading RTL:: Reading textual RTL from a file.
+
+\1f
+File: gccint.info, Node: RTL Objects, Next: RTL Classes, Up: RTL
+
+8.1 RTL Object Types
+====================
+
+RTL uses five kinds of objects: expressions, integers, wide integers,
+strings and vectors. Expressions are the most important ones. An RTL
+expression ("RTX", for short) is a C structure, but it is usually
+referred to with a pointer; a type that is given the typedef name `rtx'.
+
+ An integer is simply an `int'; their written form uses decimal
+digits. A wide integer is an integral object whose type is
+`HOST_WIDE_INT'; their written form uses decimal digits.
+
+ A string is a sequence of characters. In core it is represented as a
+`char *' in usual C fashion, and it is written in C syntax as well.
+However, strings in RTL may never be null. If you write an empty
+string in a machine description, it is represented in core as a null
+pointer rather than as a pointer to a null character. In certain
+contexts, these null pointers instead of strings are valid. Within RTL
+code, strings are most commonly found inside `symbol_ref' expressions,
+but they appear in other contexts in the RTL expressions that make up
+machine descriptions.
+
+ In a machine description, strings are normally written with double
+quotes, as you would in C. However, strings in machine descriptions may
+extend over many lines, which is invalid C, and adjacent string
+constants are not concatenated as they are in C. Any string constant
+may be surrounded with a single set of parentheses. Sometimes this
+makes the machine description easier to read.
+
+ There is also a special syntax for strings, which can be useful when
+C code is embedded in a machine description. Wherever a string can
+appear, it is also valid to write a C-style brace block. The entire
+brace block, including the outermost pair of braces, is considered to be
+the string constant. Double quote characters inside the braces are not
+special. Therefore, if you write string constants in the C code, you
+need not escape each quote character with a backslash.
+
+ A vector contains an arbitrary number of pointers to expressions.
+The number of elements in the vector is explicitly present in the
+vector. The written form of a vector consists of square brackets
+(`[...]') surrounding the elements, in sequence and with whitespace
+separating them. Vectors of length zero are not created; null pointers
+are used instead.
+
+ Expressions are classified by "expression codes" (also called RTX
+codes). The expression code is a name defined in `rtl.def', which is
+also (in upper case) a C enumeration constant. The possible expression
+codes and their meanings are machine-independent. The code of an RTX
+can be extracted with the macro `GET_CODE (X)' and altered with
+`PUT_CODE (X, NEWCODE)'.
+
+ The expression code determines how many operands the expression
+contains, and what kinds of objects they are. In RTL, unlike Lisp, you
+cannot tell by looking at an operand what kind of object it is.
+Instead, you must know from its context--from the expression code of
+the containing expression. For example, in an expression of code
+`subreg', the first operand is to be regarded as an expression and the
+second operand as an integer. In an expression of code `plus', there
+are two operands, both of which are to be regarded as expressions. In
+a `symbol_ref' expression, there is one operand, which is to be
+regarded as a string.
+
+ Expressions are written as parentheses containing the name of the
+expression type, its flags and machine mode if any, and then the
+operands of the expression (separated by spaces).
+
+ Expression code names in the `md' file are written in lower case,
+but when they appear in C code they are written in upper case. In this
+manual, they are shown as follows: `const_int'.
+
+ In a few contexts a null pointer is valid where an expression is
+normally wanted. The written form of this is `(nil)'.
+
+\1f
+File: gccint.info, Node: RTL Classes, Next: Accessors, Prev: RTL Objects, Up: RTL
+
+8.2 RTL Classes and Formats
+===========================
+
+The various expression codes are divided into several "classes", which
+are represented by single characters. You can determine the class of
+an RTX code with the macro `GET_RTX_CLASS (CODE)'. Currently,
+`rtx.def' defines these classes:
+
+`o'
+ An RTX code that represents an actual object, such as a register
+ (`REG') or a memory location (`MEM', `SYMBOL_REF'). Constants and
+ basic transforms on objects (`ADDRESSOF', `HIGH', `LO_SUM') are
+ also included. Note that `SUBREG' and `STRICT_LOW_PART' are not
+ in this class, but in class `x'.
+
+`<'
+ An RTX code for a comparison, such as `NE' or `LT'.
+
+`1'
+ An RTX code for a unary arithmetic operation, such as `NEG',
+ `NOT', or `ABS'. This category also includes value extension
+ (sign or zero) and conversions between integer and floating point.
+
+`c'
+ An RTX code for a commutative binary operation, such as `PLUS' or
+ `AND'. `NE' and `EQ' are comparisons, so they have class `<'.
+
+`2'
+ An RTX code for a non-commutative binary operation, such as
+ `MINUS', `DIV', or `ASHIFTRT'.
+
+`b'
+ An RTX code for a bit-field operation. Currently only
+ `ZERO_EXTRACT' and `SIGN_EXTRACT'. These have three inputs and
+ are lvalues (so they can be used for insertion as well). *Note
+ Bit-Fields::.
+
+`3'
+ An RTX code for other three input operations. Currently only
+ `IF_THEN_ELSE'.
+
+`i'
+ An RTX code for an entire instruction: `INSN', `JUMP_INSN', and
+ `CALL_INSN'. *Note Insns::.
+
+`m'
+ An RTX code for something that matches in insns, such as
+ `MATCH_DUP'. These only occur in machine descriptions.
+
+`a'
+ An RTX code for an auto-increment addressing mode, such as
+ `POST_INC'.
+
+`x'
+ All other RTX codes. This category includes the remaining codes
+ used only in machine descriptions (`DEFINE_*', etc.). It also
+ includes all the codes describing side effects (`SET', `USE',
+ `CLOBBER', etc.) and the non-insns that may appear on an insn
+ chain, such as `NOTE', `BARRIER', and `CODE_LABEL'.
+
+ For each expression code, `rtl.def' specifies the number of
+contained objects and their kinds using a sequence of characters called
+the "format" of the expression code. For example, the format of
+`subreg' is `ei'.
+
+ These are the most commonly used format characters:
+
+`e'
+ An expression (actually a pointer to an expression).
+
+`i'
+ An integer.
+
+`w'
+ A wide integer.
+
+`s'
+ A string.
+
+`E'
+ A vector of expressions.
+
+ A few other format characters are used occasionally:
+
+`u'
+ `u' is equivalent to `e' except that it is printed differently in
+ debugging dumps. It is used for pointers to insns.
+
+`n'
+ `n' is equivalent to `i' except that it is printed differently in
+ debugging dumps. It is used for the line number or code number of
+ a `note' insn.
+
+`S'
+ `S' indicates a string which is optional. In the RTL objects in
+ core, `S' is equivalent to `s', but when the object is read, from
+ an `md' file, the string value of this operand may be omitted. An
+ omitted string is taken to be the null string.
+
+`V'
+ `V' indicates a vector which is optional. In the RTL objects in
+ core, `V' is equivalent to `E', but when the object is read from
+ an `md' file, the vector value of this operand may be omitted. An
+ omitted vector is effectively the same as a vector of no elements.
+
+`0'
+ `0' means a slot whose contents do not fit any normal category.
+ `0' slots are not printed at all in dumps, and are often used in
+ special ways by small parts of the compiler.
+
+ There are macros to get the number of operands and the format of an
+expression code:
+
+`GET_RTX_LENGTH (CODE)'
+ Number of operands of an RTX of code CODE.
+
+`GET_RTX_FORMAT (CODE)'
+ The format of an RTX of code CODE, as a C string.
+
+ Some classes of RTX codes always have the same format. For example,
+it is safe to assume that all comparison operations have format `ee'.
+
+`1'
+ All codes of this class have format `e'.
+
+`<'
+`c'
+`2'
+ All codes of these classes have format `ee'.
+
+`b'
+`3'
+ All codes of these classes have format `eee'.
+
+`i'
+ All codes of this class have formats that begin with `iuueiee'.
+ *Note Insns::. Note that not all RTL objects linked onto an insn
+ chain are of class `i'.
+
+`o'
+`m'
+`x'
+ You can make no assumptions about the format of these codes.
+
+\1f
+File: gccint.info, Node: Accessors, Next: Flags, Prev: RTL Classes, Up: RTL
+
+8.3 Access to Operands
+======================
+
+Operands of expressions are accessed using the macros `XEXP', `XINT',
+`XWINT' and `XSTR'. Each of these macros takes two arguments: an
+expression-pointer (RTX) and an operand number (counting from zero).
+Thus,
+
+ XEXP (X, 2)
+
+accesses operand 2 of expression X, as an expression.
+
+ XINT (X, 2)
+
+accesses the same operand as an integer. `XSTR', used in the same
+fashion, would access it as a string.
+
+ Any operand can be accessed as an integer, as an expression or as a
+string. You must choose the correct method of access for the kind of
+value actually stored in the operand. You would do this based on the
+expression code of the containing expression. That is also how you
+would know how many operands there are.
+
+ For example, if X is a `subreg' expression, you know that it has two
+operands which can be correctly accessed as `XEXP (X, 0)' and `XINT (X,
+1)'. If you did `XINT (X, 0)', you would get the address of the
+expression operand but cast as an integer; that might occasionally be
+useful, but it would be cleaner to write `(int) XEXP (X, 0)'. `XEXP
+(X, 1)' would also compile without error, and would return the second,
+integer operand cast as an expression pointer, which would probably
+result in a crash when accessed. Nothing stops you from writing `XEXP
+(X, 28)' either, but this will access memory past the end of the
+expression with unpredictable results.
+
+ Access to operands which are vectors is more complicated. You can
+use the macro `XVEC' to get the vector-pointer itself, or the macros
+`XVECEXP' and `XVECLEN' to access the elements and length of a vector.
+
+`XVEC (EXP, IDX)'
+ Access the vector-pointer which is operand number IDX in EXP.
+
+`XVECLEN (EXP, IDX)'
+ Access the length (number of elements) in the vector which is in
+ operand number IDX in EXP. This value is an `int'.
+
+`XVECEXP (EXP, IDX, ELTNUM)'
+ Access element number ELTNUM in the vector which is in operand
+ number IDX in EXP. This value is an RTX.
+
+ It is up to you to make sure that ELTNUM is not negative and is
+ less than `XVECLEN (EXP, IDX)'.
+
+ All the macros defined in this section expand into lvalues and
+therefore can be used to assign the operands, lengths and vector
+elements as well as to access them.
+
+\1f
+File: gccint.info, Node: Flags, Next: Machine Modes, Prev: Accessors, Up: RTL
+
+8.4 Flags in an RTL Expression
+==============================
+
+RTL expressions contain several flags (one-bit bit-fields) that are
+used in certain types of expression. Most often they are accessed with
+the following macros, which expand into lvalues:
+
+`CONSTANT_POOL_ADDRESS_P (X)'
+ Nonzero in a `symbol_ref' if it refers to part of the current
+ function's constant pool. For most targets these addresses are in
+ a `.rodata' section entirely separate from the function, but for
+ some targets the addresses are close to the beginning of the
+ function. In either case GCC assumes these addresses can be
+ addressed directly, perhaps with the help of base registers.
+ Stored in the `unchanging' field and printed as `/u'.
+
+`CONST_OR_PURE_CALL_P (X)'
+ In a `call_insn', `note', or an `expr_list' for notes, indicates
+ that the insn represents a call to a const or pure function.
+ Stored in the `unchanging' field and printed as `/u'.
+
+`INSN_ANNULLED_BRANCH_P (X)'
+ In an `insn' in the delay slot of a branch insn, indicates that an
+ annulling branch should be used. See the discussion under
+ `sequence' below. Stored in the `unchanging' field and printed as
+ `/u'.
+
+`INSN_DEAD_CODE_P (X)'
+ In an `insn' during the dead-code elimination pass, nonzero if the
+ insn is dead. Stored in the `in_struct' field and printed as `/s'.
+
+`INSN_DELETED_P (X)'
+ In an `insn', nonzero if the insn has been deleted. Stored in the
+ `volatil' field and printed as `/v'.
+
+`INSN_FROM_TARGET_P (X)'
+ In an `insn' in a delay slot of a branch, indicates that the insn
+ is from the target of the branch. If the branch insn has
+ `INSN_ANNULLED_BRANCH_P' set, this insn will only be executed if
+ the branch is taken. For annulled branches with
+ `INSN_FROM_TARGET_P' clear, the insn will be executed only if the
+ branch is not taken. When `INSN_ANNULLED_BRANCH_P' is not set,
+ this insn will always be executed. Stored in the `in_struct'
+ field and printed as `/s'.
+
+`LABEL_OUTSIDE_LOOP_P (X)'
+ In `label_ref' expressions, nonzero if this is a reference to a
+ label that is outside the innermost loop containing the reference
+ to the label. Stored in the `in_struct' field and printed as `/s'.
+
+`LABEL_PRESERVE_P (X)'
+ In a `code_label', indicates that the label is referenced by code
+ or data not visible to the RTL of a given function. Labels
+ referenced by a non-local goto will have this bit set. Stored in
+ the `in_struct' field and printed as `/s'.
+
+`LABEL_REF_NONLOCAL_P (X)'
+ In `label_ref' and `reg_label' expressions, nonzero if this is a
+ reference to a non-local label. Stored in the `volatil' field and
+ printed as `/v'.
+
+`LINK_COST_FREE (X)'
+ In the `LOG_LINKS' `insn_list' during scheduling, nonzero when the
+ cost of executing an instruction through the link is zero, i.e.,
+ the link makes the cost free. Stored in the `call' field and
+ printed as `/c'.
+
+`LINK_COST_ZERO (X)'
+ In the `LOG_LINKS' `insn_list' during scheduling, nonzero when the
+ cost of executing an instruction through the link varies and is
+ unchanged, i.e., the link has zero additional cost. Stored in the
+ `jump' field and printed as `/j'.
+
+`MEM_IN_STRUCT_P (X)'
+ In `mem' expressions, nonzero for reference to an entire structure,
+ union or array, or to a component of one. Zero for references to a
+ scalar variable or through a pointer to a scalar. If both this
+ flag and `MEM_SCALAR_P' are clear, then we don't know whether this
+ `mem' is in a structure or not. Both flags should never be
+ simultaneously set. Stored in the `in_struct' field and printed
+ as `/s'.
+
+`MEM_KEEP_ALIAS_SET_P (X)'
+ In `mem' expressions, 1 if we should keep the alias set for this
+ mem unchanged when we access a component. Set to 1, for example,
+ when we are already in a non-addressable component of an aggregate.
+ Stored in the `jump' field and printed as `/j'.
+
+`MEM_SCALAR_P (X)'
+ In `mem' expressions, nonzero for reference to a scalar known not
+ to be a member of a structure, union, or array. Zero for such
+ references and for indirections through pointers, even pointers
+ pointing to scalar types. If both this flag and `MEM_IN_STRUCT_P'
+ are clear, then we don't know whether this `mem' is in a structure
+ or not. Both flags should never be simultaneously set. Stored in
+ the `frame_related' field and printed as `/f'.
+
+`MEM_VOLATILE_P (X)'
+ In `mem' and `asm_operands' expressions, nonzero for volatile
+ memory references. Stored in the `volatil' field and printed as
+ `/v'.
+
+`REG_FUNCTION_VALUE_P (X)'
+ Nonzero in a `reg' if it is the place in which this function's
+ value is going to be returned. (This happens only in a hard
+ register.) Stored in the `integrated' field and printed as `/i'.
+
+`REG_LOOP_TEST_P (X)'
+ In `reg' expressions, nonzero if this register's entire life is
+ contained in the exit test code for some loop. Stored in the
+ `in_struct' field and printed as `/s'.
+
+`REG_POINTER (X)'
+ Nonzero in a `reg' if the register holds a pointer. Stored in the
+ `frame_related' field and printed as `/f'.
+
+`REG_USERVAR_P (X)'
+ In a `reg', nonzero if it corresponds to a variable present in the
+ user's source code. Zero for temporaries generated internally by
+ the compiler. Stored in the `volatil' field and printed as `/v'.
+
+ The same hard register may be used also for collecting the values
+ of functions called by this one, but `REG_FUNCTION_VALUE_P' is zero
+ in this kind of use.
+
+`RTX_FRAME_RELATED_P (X)'
+ Nonzero in an `insn' or `set' which is part of a function prologue
+ and sets the stack pointer, sets the frame pointer, or saves a
+ register. This flag should also be set on an instruction that
+ sets up a temporary register to use in place of the frame pointer.
+ Stored in the `frame_related' field and printed as `/f'.
+
+ In particular, on RISC targets where there are limits on the sizes
+ of immediate constants, it is sometimes impossible to reach the
+ register save area directly from the stack pointer. In that case,
+ a temporary register is used that is near enough to the register
+ save area, and the Canonical Frame Address, i.e., DWARF2's logical
+ frame pointer, register must (temporarily) be changed to be this
+ temporary register. So, the instruction that sets this temporary
+ register must be marked as `RTX_FRAME_RELATED_P'.
+
+ If the marked instruction is overly complex (defined in terms of
+ what `dwarf2out_frame_debug_expr' can handle), you will also have
+ to create a `REG_FRAME_RELATED_EXPR' note and attach it to the
+ instruction. This note should contain a simple expression of the
+ computation performed by this instruction, i.e., one that
+ `dwarf2out_frame_debug_expr' can handle.
+
+ This flag is required for exception handling support on targets
+ with RTL prologues.
+
+`RTX_INTEGRATED_P (X)'
+ Nonzero in an `insn', `insn_list', or `const' if it resulted from
+ an in-line function call. Stored in the `integrated' field and
+ printed as `/i'.
+
+`RTX_UNCHANGING_P (X)'
+ Nonzero in a `reg' or `mem' if the memory is set at most once,
+ anywhere. This does not mean that it is function invariant.
+ Stored in the `unchanging' field and printed as `/u'.
+
+`SCHED_GROUP_P (X)'
+ During instruction scheduling, in an `insn', indicates that the
+ previous insn must be scheduled together with this insn. This is
+ used to ensure that certain groups of instructions will not be
+ split up by the instruction scheduling pass, for example, `use'
+ insns before a `call_insn' may not be separated from the
+ `call_insn'. Stored in the `in_struct' field and printed as `/s'.
+
+`SET_IS_RETURN_P (X)'
+ For a `set', nonzero if it is for a return. Stored in the `jump'
+ field and printed as `/j'.
+
+`SIBLING_CALL_P (X)'
+ For a `call_insn', nonzero if the insn is a sibling call. Stored
+ in the `jump' field and printed as `/j'.
+
+`STRING_POOL_ADDRESS_P (X)'
+ For a `symbol_ref' expression, nonzero if it addresses this
+ function's string constant pool. Stored in the `frame_related'
+ field and printed as `/f'.
+
+`SUBREG_PROMOTED_UNSIGNED_P (X)'
+ Nonzero in a `subreg' that has `SUBREG_PROMOTED_VAR_P' nonzero if
+ the object being referenced is kept zero-extended and zero if it
+ is kept sign-extended. Stored in the `unchanging' field and
+ printed as `/u'.
+
+`SUBREG_PROMOTED_VAR_P (X)'
+ Nonzero in a `subreg' if it was made when accessing an object that
+ was promoted to a wider mode in accord with the `PROMOTED_MODE'
+ machine description macro (*note Storage Layout::). In this case,
+ the mode of the `subreg' is the declared mode of the object and
+ the mode of `SUBREG_REG' is the mode of the register that holds
+ the object. Promoted variables are always either sign- or
+ zero-extended to the wider mode on every assignment. Stored in
+ the `in_struct' field and printed as `/s'.
+
+`SYMBOL_REF_FLAG (X)'
+ In a `symbol_ref', this is used as a flag for machine-specific
+ purposes. Stored in the `volatil' field and printed as `/v'.
+
+`SYMBOL_REF_USED (X)'
+ In a `symbol_ref', indicates that X has been used. This is
+ normally only used to ensure that X is only declared external
+ once. Stored in the `used' field.
+
+`SYMBOL_REF_WEAK (X)'
+ In a `symbol_ref', indicates that X has been declared weak.
+ Stored in the `integrated' field and printed as `/i'.
+
+ These are the fields to which the above macros refer:
+
+`call'
+ In the `LOG_LINKS' of an `insn_list' during scheduling, 1 means
+ that the cost of executing an instruction through the link is zero.
+
+ In an RTL dump, this flag is represented as `/c'.
+
+`frame_related'
+ In an `insn' or `set' expression, 1 means that it is part of a
+ function prologue and sets the stack pointer, sets the frame
+ pointer, saves a register, or sets up a temporary register to use
+ in place of the frame pointer.
+
+ In `reg' expressions, 1 means that the register holds a pointer.
+
+ In `symbol_ref' expressions, 1 means that the reference addresses
+ this function's string constant pool.
+
+ In `mem' expressions, 1 means that the reference is to a scalar.
+
+ In an RTL dump, this flag is represented as `/f'.
+
+`in_struct'
+ In `mem' expressions, it is 1 if the memory datum referred to is
+ all or part of a structure or array; 0 if it is (or might be) a
+ scalar variable. A reference through a C pointer has 0 because
+ the pointer might point to a scalar variable. This information
+ allows the compiler to determine something about possible cases of
+ aliasing.
+
+ In `reg' expressions, it is 1 if the register has its entire life
+ contained within the test expression of some loop.
+
+ In `subreg' expressions, 1 means that the `subreg' is accessing an
+ object that has had its mode promoted from a wider mode.
+
+ In `label_ref' expressions, 1 means that the referenced label is
+ outside the innermost loop containing the insn in which the
+ `label_ref' was found.
+
+ In `code_label' expressions, it is 1 if the label may never be
+ deleted. This is used for labels which are the target of
+ non-local gotos. Such a label that would have been deleted is
+ replaced with a `note' of type `NOTE_INSN_DELETED_LABEL'.
+
+ In an `insn' during dead-code elimination, 1 means that the insn is
+ dead code.
+
+ In an `insn' during reorg for an insn in the delay slot of a
+ branch, 1 means that this insn is from the target of the branch.
+
+ In an `insn' during instruction scheduling, 1 means that this insn
+ must be scheduled as part of a group together with the previous
+ insn.
+
+ In an RTL dump, this flag is represented as `/s'.
+
+`integrated'
+ In an `insn', `insn_list', or `const', 1 means the RTL was
+ produced by procedure integration.
+
+ In `reg' expressions, 1 means the register contains the value to
+ be returned by the current function. On machines that pass
+ parameters in registers, the same register number may be used for
+ parameters as well, but this flag is not set on such uses.
+
+ In `symbol_ref' expressions, 1 means the referenced symbol is weak.
+
+ In an RTL dump, this flag is represented as `/i'.
+
+`jump'
+ In a `mem' expression, 1 means we should keep the alias set for
+ this mem unchanged when we access a component.
+
+ In a `set', 1 means it is for a return.
+
+ In a `call_insn', 1 means it is a sibling call.
+
+ In the `LOG_LINKS' of an `insn_list' during scheduling, 1 means the
+ cost of executing an instruction through the link varies and is
+ unchanging.
+
+ In an RTL dump, this flag is represented as `/j'.
+
+`unchanging'
+ In `reg' and `mem' expressions, 1 means that the value of the
+ expression never changes.
+
+ In `subreg' expressions, it is 1 if the `subreg' references an
+ unsigned object whose mode has been promoted to a wider mode.
+
+ In an `insn', 1 means that this is an annulling branch.
+
+ In a `symbol_ref' expression, 1 means that this symbol addresses
+ something in the per-function constant pool.
+
+ In a `call_insn', `note', or an `expr_list' of notes, 1 means that
+ this instruction is a call to a const or pure function.
+
+ In an RTL dump, this flag is represented as `/u'.
+
+`used'
+ This flag is used directly (without an access macro) at the end of
+ RTL generation for a function, to count the number of times an
+ expression appears in insns. Expressions that appear more than
+ once are copied, according to the rules for shared structure
+ (*note Sharing::).
+
+ For a `reg', it is used directly (without an access macro) by the
+ leaf register renumbering code to ensure that each register is only
+ renumbered once.
+
+ In a `symbol_ref', it indicates that an external declaration for
+ the symbol has already been written.
+
+`volatil'
+ In a `mem' or `asm_operands' expression, it is 1 if the memory
+ reference is volatile. Volatile memory references may not be
+ deleted, reordered or combined.
+
+ In a `symbol_ref' expression, it is used for machine-specific
+ purposes.
+
+ In a `reg' expression, it is 1 if the value is a user-level
+ variable. 0 indicates an internal compiler temporary.
+
+ In an `insn', 1 means the insn has been deleted.
+
+ In `label_ref' and `reg_label' expressions, 1 means a reference to
+ a non-local label.
+
+ In an RTL dump, this flag is represented as `/v'.
+
+\1f
+File: gccint.info, Node: Machine Modes, Next: Constants, Prev: Flags, Up: RTL
+
+8.5 Machine Modes
+=================
+
+A machine mode describes a size of data object and the representation
+used for it. In the C code, machine modes are represented by an
+enumeration type, `enum machine_mode', defined in `machmode.def'. Each
+RTL expression has room for a machine mode and so do certain kinds of
+tree expressions (declarations and types, to be precise).
+
+ In debugging dumps and machine descriptions, the machine mode of an
+RTL expression is written after the expression code with a colon to
+separate them. The letters `mode' which appear at the end of each
+machine mode name are omitted. For example, `(reg:SI 38)' is a `reg'
+expression with machine mode `SImode'. If the mode is `VOIDmode', it
+is not written at all.
+
+ Here is a table of machine modes. The term "byte" below refers to an
+object of `BITS_PER_UNIT' bits (*note Storage Layout::).
+
+`BImode'
+ "Bit" mode represents a single bit, for predicate registers.
+
+`QImode'
+ "Quarter-Integer" mode represents a single byte treated as an
+ integer.
+
+`HImode'
+ "Half-Integer" mode represents a two-byte integer.
+
+`PSImode'
+ "Partial Single Integer" mode represents an integer which occupies
+ four bytes but which doesn't really use all four. On some
+ machines, this is the right mode to use for pointers.
+
+`SImode'
+ "Single Integer" mode represents a four-byte integer.
+
+`PDImode'
+ "Partial Double Integer" mode represents an integer which occupies
+ eight bytes but which doesn't really use all eight. On some
+ machines, this is the right mode to use for certain pointers.
+
+`DImode'
+ "Double Integer" mode represents an eight-byte integer.
+
+`TImode'
+ "Tetra Integer" (?) mode represents a sixteen-byte integer.
+
+`OImode'
+ "Octa Integer" (?) mode represents a thirty-two-byte integer.
+
+`QFmode'
+ "Quarter-Floating" mode represents a quarter-precision (single
+ byte) floating point number.
+
+`HFmode'
+ "Half-Floating" mode represents a half-precision (two byte)
+ floating point number.
+
+`TQFmode'
+ "Three-Quarter-Floating" (?) mode represents a
+ three-quarter-precision (three byte) floating point number.
+
+`SFmode'
+ "Single Floating" mode represents a four byte floating point
+ number. In the common case, of a processor with IEEE arithmetic
+ and 8-bit bytes, this is a single-precision IEEE floating point
+ number; it can also be used for double-precision (on processors
+ with 16-bit bytes) and single-precision VAX and IBM types.
+
+`DFmode'
+ "Double Floating" mode represents an eight byte floating point
+ number. In the common case, of a processor with IEEE arithmetic
+ and 8-bit bytes, this is a double-precision IEEE floating point
+ number.
+
+`XFmode'
+ "Extended Floating" mode represents a twelve byte floating point
+ number. This mode is used for IEEE extended floating point. On
+ some systems not all bits within these bytes will actually be used.
+
+`TFmode'
+ "Tetra Floating" mode represents a sixteen byte floating point
+ number. This gets used for both the 96-bit extended IEEE
+ floating-point types padded to 128 bits, and true 128-bit extended
+ IEEE floating-point types.
+
+`CCmode'
+ "Condition Code" mode represents the value of a condition code,
+ which is a machine-specific set of bits used to represent the
+ result of a comparison operation. Other machine-specific modes
+ may also be used for the condition code. These modes are not used
+ on machines that use `cc0' (see *note Condition Code::).
+
+`BLKmode'
+ "Block" mode represents values that are aggregates to which none of
+ the other modes apply. In RTL, only memory references can have
+ this mode, and only if they appear in string-move or vector
+ instructions. On machines which have no such instructions,
+ `BLKmode' will not appear in RTL.
+
+`VOIDmode'
+ Void mode means the absence of a mode or an unspecified mode. For
+ example, RTL expressions of code `const_int' have mode `VOIDmode'
+ because they can be taken to have whatever mode the context
+ requires. In debugging dumps of RTL, `VOIDmode' is expressed by
+ the absence of any mode.
+
+`QCmode, HCmode, SCmode, DCmode, XCmode, TCmode'
+ These modes stand for a complex number represented as a pair of
+ floating point values. The floating point values are in `QFmode',
+ `HFmode', `SFmode', `DFmode', `XFmode', and `TFmode', respectively.
+
+`CQImode, CHImode, CSImode, CDImode, CTImode, COImode'
+ These modes stand for a complex number represented as a pair of
+ integer values. The integer values are in `QImode', `HImode',
+ `SImode', `DImode', `TImode', and `OImode', respectively.
+
+ The machine description defines `Pmode' as a C macro which expands
+into the machine mode used for addresses. Normally this is the mode
+whose size is `BITS_PER_WORD', `SImode' on 32-bit machines.
+
+ The only modes which a machine description must support are
+`QImode', and the modes corresponding to `BITS_PER_WORD',
+`FLOAT_TYPE_SIZE' and `DOUBLE_TYPE_SIZE'. The compiler will attempt to
+use `DImode' for 8-byte structures and unions, but this can be
+prevented by overriding the definition of `MAX_FIXED_MODE_SIZE'.
+Alternatively, you can have the compiler use `TImode' for 16-byte
+structures and unions. Likewise, you can arrange for the C type `short
+int' to avoid using `HImode'.
+
+ Very few explicit references to machine modes remain in the compiler
+and these few references will soon be removed. Instead, the machine
+modes are divided into mode classes. These are represented by the
+enumeration type `enum mode_class' defined in `machmode.h'. The
+possible mode classes are:
+
+`MODE_INT'
+ Integer modes. By default these are `BImode', `QImode', `HImode',
+ `SImode', `DImode', `TImode', and `OImode'.
+
+`MODE_PARTIAL_INT'
+ The "partial integer" modes, `PQImode', `PHImode', `PSImode' and
+ `PDImode'.
+
+`MODE_FLOAT'
+ Floating point modes. By default these are `QFmode', `HFmode',
+ `TQFmode', `SFmode', `DFmode', `XFmode' and `TFmode'.
+
+`MODE_COMPLEX_INT'
+ Complex integer modes. (These are not currently implemented).
+
+`MODE_COMPLEX_FLOAT'
+ Complex floating point modes. By default these are `QCmode',
+ `HCmode', `SCmode', `DCmode', `XCmode', and `TCmode'.
+
+`MODE_FUNCTION'
+ Algol or Pascal function variables including a static chain.
+ (These are not currently implemented).
+
+`MODE_CC'
+ Modes representing condition code values. These are `CCmode' plus
+ any modes listed in the `EXTRA_CC_MODES' macro. *Note Jump
+ Patterns::, also see *note Condition Code::.
+
+`MODE_RANDOM'
+ This is a catchall mode class for modes which don't fit into the
+ above classes. Currently `VOIDmode' and `BLKmode' are in
+ `MODE_RANDOM'.
+
+ Here are some C macros that relate to machine modes:
+
+`GET_MODE (X)'
+ Returns the machine mode of the RTX X.
+
+`PUT_MODE (X, NEWMODE)'
+ Alters the machine mode of the RTX X to be NEWMODE.
+
+`NUM_MACHINE_MODES'
+ Stands for the number of machine modes available on the target
+ machine. This is one greater than the largest numeric value of any
+ machine mode.
+
+`GET_MODE_NAME (M)'
+ Returns the name of mode M as a string.
+
+`GET_MODE_CLASS (M)'
+ Returns the mode class of mode M.
+
+`GET_MODE_WIDER_MODE (M)'
+ Returns the next wider natural mode. For example, the expression
+ `GET_MODE_WIDER_MODE (QImode)' returns `HImode'.
+
+`GET_MODE_SIZE (M)'
+ Returns the size in bytes of a datum of mode M.
+
+`GET_MODE_BITSIZE (M)'
+ Returns the size in bits of a datum of mode M.
+
+`GET_MODE_MASK (M)'
+ Returns a bitmask containing 1 for all bits in a word that fit
+ within mode M. This macro can only be used for modes whose
+ bitsize is less than or equal to `HOST_BITS_PER_INT'.
+
+`GET_MODE_ALIGNMENT (M)'
+ Return the required alignment, in bits, for an object of mode M.
+
+`GET_MODE_UNIT_SIZE (M)'
+ Returns the size in bytes of the subunits of a datum of mode M.
+ This is the same as `GET_MODE_SIZE' except in the case of complex
+ modes. For them, the unit size is the size of the real or
+ imaginary part.
+
+`GET_MODE_NUNITS (M)'
+ Returns the number of units contained in a mode, i.e.,
+ `GET_MODE_SIZE' divided by `GET_MODE_UNIT_SIZE'.
+
+`GET_CLASS_NARROWEST_MODE (C)'
+ Returns the narrowest mode in mode class C.
+
+ The global variables `byte_mode' and `word_mode' contain modes whose
+classes are `MODE_INT' and whose bitsizes are either `BITS_PER_UNIT' or
+`BITS_PER_WORD', respectively. On 32-bit machines, these are `QImode'
+and `SImode', respectively.
+
+\1f
+File: gccint.info, Node: Constants, Next: Regs and Memory, Prev: Machine Modes, Up: RTL
+
+8.6 Constant Expression Types
+=============================
+
+The simplest RTL expressions are those that represent constant values.
+
+`(const_int I)'
+ This type of expression represents the integer value I. I is
+ customarily accessed with the macro `INTVAL' as in `INTVAL (EXP)',
+ which is equivalent to `XWINT (EXP, 0)'.
+
+ There is only one expression object for the integer value zero; it
+ is the value of the variable `const0_rtx'. Likewise, the only
+ expression for integer value one is found in `const1_rtx', the only
+ expression for integer value two is found in `const2_rtx', and the
+ only expression for integer value negative one is found in
+ `constm1_rtx'. Any attempt to create an expression of code
+ `const_int' and value zero, one, two or negative one will return
+ `const0_rtx', `const1_rtx', `const2_rtx' or `constm1_rtx' as
+ appropriate.
+
+ Similarly, there is only one object for the integer whose value is
+ `STORE_FLAG_VALUE'. It is found in `const_true_rtx'. If
+ `STORE_FLAG_VALUE' is one, `const_true_rtx' and `const1_rtx' will
+ point to the same object. If `STORE_FLAG_VALUE' is -1,
+ `const_true_rtx' and `constm1_rtx' will point to the same object.
+
+`(const_double:M ADDR I0 I1 ...)'
+ Represents either a floating-point constant of mode M or an
+ integer constant too large to fit into `HOST_BITS_PER_WIDE_INT'
+ bits but small enough to fit within twice that number of bits (GCC
+ does not provide a mechanism to represent even larger constants).
+ In the latter case, M will be `VOIDmode'.
+
+`(const_vector:M [X0 X1 ...])'
+ Represents a vector constant. The square brackets stand for the
+ vector containing the constant elements. X0, X1 and so on are the
+ `const_int' or `const_double' elements.
+
+ The number of units in a `const_vector' is obtained with the macro
+ `CONST_VECTOR_NUNITS' as in `CONST_VECTOR_NUNITS (V)'.
+
+ Individual elements in a vector constant are accessed with the
+ macro `CONST_VECTOR_ELT' as in `CONST_VECTOR_ELT (V, N)' where V
+ is the vector constant and N is the element desired.
+
+ ADDR is used to contain the `mem' expression that corresponds to
+ the location in memory that at which the constant can be found. If
+ it has not been allocated a memory location, but is on the chain
+ of all `const_double' expressions in this compilation (maintained
+ using an undisplayed field), ADDR contains `const0_rtx'. If it is
+ not on the chain, ADDR contains `cc0_rtx'. ADDR is customarily
+ accessed with the macro `CONST_DOUBLE_MEM' and the chain field via
+ `CONST_DOUBLE_CHAIN'.
+
+ If M is `VOIDmode', the bits of the value are stored in I0 and I1.
+ I0 is customarily accessed with the macro `CONST_DOUBLE_LOW' and
+ I1 with `CONST_DOUBLE_HIGH'.
+
+ If the constant is floating point (regardless of its precision),
+ then the number of integers used to store the value depends on the
+ size of `REAL_VALUE_TYPE' (*note Cross-compilation::). The
+ integers represent a floating point number, but not precisely in
+ the target machine's or host machine's floating point format. To
+ convert them to the precise bit pattern used by the target
+ machine, use the macro `REAL_VALUE_TO_TARGET_DOUBLE' and friends
+ (*note Data Output::).
+
+ The macro `CONST0_RTX (MODE)' refers to an expression with value 0
+ in mode MODE. If mode MODE is of mode class `MODE_INT', it
+ returns `const0_rtx'. If mode MODE is of mode class `MODE_FLOAT',
+ it returns a `CONST_DOUBLE' expression in mode MODE. Otherwise,
+ it returns a `CONST_VECTOR' expression in mode MODE. Similarly,
+ the macro `CONST1_RTX (MODE)' refers to an expression with value 1
+ in mode MODE and similarly for `CONST2_RTX'. The `CONST1_RTX' and
+ `CONST2_RTX' macros are undefined for vector modes.
+
+`(const_string STR)'
+ Represents a constant string with value STR. Currently this is
+ used only for insn attributes (*note Insn Attributes::) since
+ constant strings in C are placed in memory.
+
+`(symbol_ref:MODE SYMBOL)'
+ Represents the value of an assembler label for data. SYMBOL is a
+ string that describes the name of the assembler label. If it
+ starts with a `*', the label is the rest of SYMBOL not including
+ the `*'. Otherwise, the label is SYMBOL, usually prefixed with
+ `_'.
+
+ The `symbol_ref' contains a mode, which is usually `Pmode'.
+ Usually that is the only mode for which a symbol is directly valid.
+
+`(label_ref LABEL)'
+ Represents the value of an assembler label for code. It contains
+ one operand, an expression, which must be a `code_label' or a
+ `note' of type `NOTE_INSN_DELETED_LABEL' that appears in the
+ instruction sequence to identify the place where the label should
+ go.
+
+ The reason for using a distinct expression type for code label
+ references is so that jump optimization can distinguish them.
+
+`(const:M EXP)'
+ Represents a constant that is the result of an assembly-time
+ arithmetic computation. The operand, EXP, is an expression that
+ contains only constants (`const_int', `symbol_ref' and `label_ref'
+ expressions) combined with `plus' and `minus'. However, not all
+ combinations are valid, since the assembler cannot do arbitrary
+ arithmetic on relocatable symbols.
+
+ M should be `Pmode'.
+
+`(high:M EXP)'
+ Represents the high-order bits of EXP, usually a `symbol_ref'.
+ The number of bits is machine-dependent and is normally the number
+ of bits specified in an instruction that initializes the high
+ order bits of a register. It is used with `lo_sum' to represent
+ the typical two-instruction sequence used in RISC machines to
+ reference a global memory location.
+
+ M should be `Pmode'.
+
+\1f
+File: gccint.info, Node: Regs and Memory, Next: Arithmetic, Prev: Constants, Up: RTL
+
+8.7 Registers and Memory
+========================
+
+Here are the RTL expression types for describing access to machine
+registers and to main memory.
+
+`(reg:M N)'
+ For small values of the integer N (those that are less than
+ `FIRST_PSEUDO_REGISTER'), this stands for a reference to machine
+ register number N: a "hard register". For larger values of N, it
+ stands for a temporary value or "pseudo register". The compiler's
+ strategy is to generate code assuming an unlimited number of such
+ pseudo registers, and later convert them into hard registers or
+ into memory references.
+
+ M is the machine mode of the reference. It is necessary because
+ machines can generally refer to each register in more than one
+ mode. For example, a register may contain a full word but there
+ may be instructions to refer to it as a half word or as a single
+ byte, as well as instructions to refer to it as a floating point
+ number of various precisions.
+
+ Even for a register that the machine can access in only one mode,
+ the mode must always be specified.
+
+ The symbol `FIRST_PSEUDO_REGISTER' is defined by the machine
+ description, since the number of hard registers on the machine is
+ an invariant characteristic of the machine. Note, however, that
+ not all of the machine registers must be general registers. All
+ the machine registers that can be used for storage of data are
+ given hard register numbers, even those that can be used only in
+ certain instructions or can hold only certain types of data.
+
+ A hard register may be accessed in various modes throughout one
+ function, but each pseudo register is given a natural mode and is
+ accessed only in that mode. When it is necessary to describe an
+ access to a pseudo register using a nonnatural mode, a `subreg'
+ expression is used.
+
+ A `reg' expression with a machine mode that specifies more than
+ one word of data may actually stand for several consecutive
+ registers. If in addition the register number specifies a
+ hardware register, then it actually represents several consecutive
+ hardware registers starting with the specified one.
+
+ Each pseudo register number used in a function's RTL code is
+ represented by a unique `reg' expression.
+
+ Some pseudo register numbers, those within the range of
+ `FIRST_VIRTUAL_REGISTER' to `LAST_VIRTUAL_REGISTER' only appear
+ during the RTL generation phase and are eliminated before the
+ optimization phases. These represent locations in the stack frame
+ that cannot be determined until RTL generation for the function
+ has been completed. The following virtual register numbers are
+ defined:
+
+ `VIRTUAL_INCOMING_ARGS_REGNUM'
+ This points to the first word of the incoming arguments
+ passed on the stack. Normally these arguments are placed
+ there by the caller, but the callee may have pushed some
+ arguments that were previously passed in registers.
+
+ When RTL generation is complete, this virtual register is
+ replaced by the sum of the register given by
+ `ARG_POINTER_REGNUM' and the value of `FIRST_PARM_OFFSET'.
+
+ `VIRTUAL_STACK_VARS_REGNUM'
+ If `FRAME_GROWS_DOWNWARD' is defined, this points to
+ immediately above the first variable on the stack.
+ Otherwise, it points to the first variable on the stack.
+
+ `VIRTUAL_STACK_VARS_REGNUM' is replaced with the sum of the
+ register given by `FRAME_POINTER_REGNUM' and the value
+ `STARTING_FRAME_OFFSET'.
+
+ `VIRTUAL_STACK_DYNAMIC_REGNUM'
+ This points to the location of dynamically allocated memory
+ on the stack immediately after the stack pointer has been
+ adjusted by the amount of memory desired.
+
+ This virtual register is replaced by the sum of the register
+ given by `STACK_POINTER_REGNUM' and the value
+ `STACK_DYNAMIC_OFFSET'.
+
+ `VIRTUAL_OUTGOING_ARGS_REGNUM'
+ This points to the location in the stack at which outgoing
+ arguments should be written when the stack is pre-pushed
+ (arguments pushed using push insns should always use
+ `STACK_POINTER_REGNUM').
+
+ This virtual register is replaced by the sum of the register
+ given by `STACK_POINTER_REGNUM' and the value
+ `STACK_POINTER_OFFSET'.
+
+`(subreg:M REG BYTENUM)'
+ `subreg' expressions are used to refer to a register in a machine
+ mode other than its natural one, or to refer to one register of a
+ multi-part `reg' that actually refers to several registers.
+
+ Each pseudo-register has a natural mode. If it is necessary to
+ operate on it in a different mode--for example, to perform a
+ fullword move instruction on a pseudo-register that contains a
+ single byte--the pseudo-register must be enclosed in a `subreg'.
+ In such a case, BYTENUM is zero.
+
+ Usually M is at least as narrow as the mode of REG, in which case
+ it is restricting consideration to only the bits of REG that are
+ in M.
+
+ Sometimes M is wider than the mode of REG. These `subreg'
+ expressions are often called "paradoxical". They are used in
+ cases where we want to refer to an object in a wider mode but do
+ not care what value the additional bits have. The reload pass
+ ensures that paradoxical references are only made to hard
+ registers.
+
+ The other use of `subreg' is to extract the individual registers of
+ a multi-register value. Machine modes such as `DImode' and
+ `TImode' can indicate values longer than a word, values which
+ usually require two or more consecutive registers. To access one
+ of the registers, use a `subreg' with mode `SImode' and a BYTENUM
+ offset that says which register.
+
+ Storing in a non-paradoxical `subreg' has undefined results for
+ bits belonging to the same word as the `subreg'. This laxity makes
+ it easier to generate efficient code for such instructions. To
+ represent an instruction that preserves all the bits outside of
+ those in the `subreg', use `strict_low_part' around the `subreg'.
+
+ The compilation parameter `WORDS_BIG_ENDIAN', if set to 1, says
+ that byte number zero is part of the most significant word;
+ otherwise, it is part of the least significant word.
+
+ The compilation parameter `BYTES_BIG_ENDIAN', if set to 1, says
+ that byte number zero is the most significant byte within a word;
+ otherwise, it is the least significant byte within a word.
+
+ On a few targets, `FLOAT_WORDS_BIG_ENDIAN' disagrees with
+ `WORDS_BIG_ENDIAN'. However, most parts of the compiler treat
+ floating point values as if they had the same endianness as
+ integer values. This works because they handle them solely as a
+ collection of integer values, with no particular numerical value.
+ Only real.c and the runtime libraries care about
+ `FLOAT_WORDS_BIG_ENDIAN'.
+
+ Between the combiner pass and the reload pass, it is possible to
+ have a paradoxical `subreg' which contains a `mem' instead of a
+ `reg' as its first operand. After the reload pass, it is also
+ possible to have a non-paradoxical `subreg' which contains a
+ `mem'; this usually occurs when the `mem' is a stack slot which
+ replaced a pseudo register.
+
+ Note that it is not valid to access a `DFmode' value in `SFmode'
+ using a `subreg'. On some machines the most significant part of a
+ `DFmode' value does not have the same format as a single-precision
+ floating value.
+
+ It is also not valid to access a single word of a multi-word value
+ in a hard register when less registers can hold the value than
+ would be expected from its size. For example, some 32-bit
+ machines have floating-point registers that can hold an entire
+ `DFmode' value. If register 10 were such a register `(subreg:SI
+ (reg:DF 10) 1)' would be invalid because there is no way to
+ convert that reference to a single machine register. The reload
+ pass prevents `subreg' expressions such as these from being formed.
+
+ The first operand of a `subreg' expression is customarily accessed
+ with the `SUBREG_REG' macro and the second operand is customarily
+ accessed with the `SUBREG_BYTE' macro.
+
+`(scratch:M)'
+ This represents a scratch register that will be required for the
+ execution of a single instruction and not used subsequently. It is
+ converted into a `reg' by either the local register allocator or
+ the reload pass.
+
+ `scratch' is usually present inside a `clobber' operation (*note
+ Side Effects::).
+
+`(cc0)'
+ This refers to the machine's condition code register. It has no
+ operands and may not have a machine mode. There are two ways to
+ use it:
+
+ * To stand for a complete set of condition code flags. This is
+ best on most machines, where each comparison sets the entire
+ series of flags.
+
+ With this technique, `(cc0)' may be validly used in only two
+ contexts: as the destination of an assignment (in test and
+ compare instructions) and in comparison operators comparing
+ against zero (`const_int' with value zero; that is to say,
+ `const0_rtx').
+
+ * To stand for a single flag that is the result of a single
+ condition. This is useful on machines that have only a
+ single flag bit, and in which comparison instructions must
+ specify the condition to test.
+
+ With this technique, `(cc0)' may be validly used in only two
+ contexts: as the destination of an assignment (in test and
+ compare instructions) where the source is a comparison
+ operator, and as the first operand of `if_then_else' (in a
+ conditional branch).
+
+ There is only one expression object of code `cc0'; it is the value
+ of the variable `cc0_rtx'. Any attempt to create an expression of
+ code `cc0' will return `cc0_rtx'.
+
+ Instructions can set the condition code implicitly. On many
+ machines, nearly all instructions set the condition code based on
+ the value that they compute or store. It is not necessary to
+ record these actions explicitly in the RTL because the machine
+ description includes a prescription for recognizing the
+ instructions that do so (by means of the macro
+ `NOTICE_UPDATE_CC'). *Note Condition Code::. Only instructions
+ whose sole purpose is to set the condition code, and instructions
+ that use the condition code, need mention `(cc0)'.
+
+ On some machines, the condition code register is given a register
+ number and a `reg' is used instead of `(cc0)'. This is usually the
+ preferable approach if only a small subset of instructions modify
+ the condition code. Other machines store condition codes in
+ general registers; in such cases a pseudo register should be used.
+
+ Some machines, such as the Sparc and RS/6000, have two sets of
+ arithmetic instructions, one that sets and one that does not set
+ the condition code. This is best handled by normally generating
+ the instruction that does not set the condition code, and making a
+ pattern that both performs the arithmetic and sets the condition
+ code register (which would not be `(cc0)' in this case). For
+ examples, search for `addcc' and `andcc' in `sparc.md'.
+
+`(pc)'
+ This represents the machine's program counter. It has no operands
+ and may not have a machine mode. `(pc)' may be validly used only
+ in certain specific contexts in jump instructions.
+
+ There is only one expression object of code `pc'; it is the value
+ of the variable `pc_rtx'. Any attempt to create an expression of
+ code `pc' will return `pc_rtx'.
+
+ All instructions that do not jump alter the program counter
+ implicitly by incrementing it, but there is no need to mention
+ this in the RTL.
+
+`(mem:M ADDR ALIAS)'
+ This RTX represents a reference to main memory at an address
+ represented by the expression ADDR. M specifies how large a unit
+ of memory is accessed. ALIAS specifies an alias set for the
+ reference. In general two items are in different alias sets if
+ they cannot reference the same memory address.
+
+`(addressof:M REG)'
+ This RTX represents a request for the address of register REG.
+ Its mode is always `Pmode'. If there are any `addressof'
+ expressions left in the function after CSE, REG is forced into the
+ stack and the `addressof' expression is replaced with a `plus'
+ expression for the address of its stack slot.
+
+\1f
+File: gccint.info, Node: Arithmetic, Next: Comparisons, Prev: Regs and Memory, Up: RTL
+
+8.8 RTL Expressions for Arithmetic
+==================================
+
+Unless otherwise specified, all the operands of arithmetic expressions
+must be valid for mode M. An operand is valid for mode M if it has
+mode M, or if it is a `const_int' or `const_double' and M is a mode of
+class `MODE_INT'.
+
+ For commutative binary operations, constants should be placed in the
+second operand.
+
+`(plus:M X Y)'
+ Represents the sum of the values represented by X and Y carried
+ out in machine mode M.
+
+`(lo_sum:M X Y)'
+ Like `plus', except that it represents that sum of X and the
+ low-order bits of Y. The number of low order bits is
+ machine-dependent but is normally the number of bits in a `Pmode'
+ item minus the number of bits set by the `high' code (*note
+ Constants::).
+
+ M should be `Pmode'.
+
+`(minus:M X Y)'
+ Like `plus' but represents subtraction.
+
+`(ss_plus:M X Y)'
+ Like `plus', but using signed saturation in case of an overflow.
+
+`(us_plus:M X Y)'
+ Like `plus', but using unsigned saturation in case of an overflow.
+
+`(ss_minus:M X Y)'
+ Like `minus', but using signed saturation in case of an overflow.
+
+`(us_minus:M X Y)'
+ Like `minus', but using unsigned saturation in case of an overflow.
+
+`(compare:M X Y)'
+ Represents the result of subtracting Y from X for purposes of
+ comparison. The result is computed without overflow, as if with
+ infinite precision.
+
+ Of course, machines can't really subtract with infinite precision.
+ However, they can pretend to do so when only the sign of the
+ result will be used, which is the case when the result is stored
+ in the condition code. And that is the _only_ way this kind of
+ expression may validly be used: as a value to be stored in the
+ condition codes, either `(cc0)' or a register. *Note
+ Comparisons::.
+
+ The mode M is not related to the modes of X and Y, but instead is
+ the mode of the condition code value. If `(cc0)' is used, it is
+ `VOIDmode'. Otherwise it is some mode in class `MODE_CC', often
+ `CCmode'. *Note Condition Code::. If M is `VOIDmode' or
+ `CCmode', the operation returns sufficient information (in an
+ unspecified format) so that any comparison operator can be applied
+ to the result of the `COMPARE' operation. For other modes in
+ class `MODE_CC', the operation only returns a subset of this
+ information.
+
+ Normally, X and Y must have the same mode. Otherwise, `compare'
+ is valid only if the mode of X is in class `MODE_INT' and Y is a
+ `const_int' or `const_double' with mode `VOIDmode'. The mode of X
+ determines what mode the comparison is to be done in; thus it must
+ not be `VOIDmode'.
+
+ If one of the operands is a constant, it should be placed in the
+ second operand and the comparison code adjusted as appropriate.
+
+ A `compare' specifying two `VOIDmode' constants is not valid since
+ there is no way to know in what mode the comparison is to be
+ performed; the comparison must either be folded during the
+ compilation or the first operand must be loaded into a register
+ while its mode is still known.
+
+`(neg:M X)'
+ Represents the negation (subtraction from zero) of the value
+ represented by X, carried out in mode M.
+
+`(mult:M X Y)'
+ Represents the signed product of the values represented by X and Y
+ carried out in machine mode M.
+
+ Some machines support a multiplication that generates a product
+ wider than the operands. Write the pattern for this as
+
+ (mult:M (sign_extend:M X) (sign_extend:M Y))
+
+ where M is wider than the modes of X and Y, which need not be the
+ same.
+
+ For unsigned widening multiplication, use the same idiom, but with
+ `zero_extend' instead of `sign_extend'.
+
+`(div:M X Y)'
+ Represents the quotient in signed division of X by Y, carried out
+ in machine mode M. If M is a floating point mode, it represents
+ the exact quotient; otherwise, the integerized quotient.
+
+ Some machines have division instructions in which the operands and
+ quotient widths are not all the same; you should represent such
+ instructions using `truncate' and `sign_extend' as in,
+
+ (truncate:M1 (div:M2 X (sign_extend:M2 Y)))
+
+`(udiv:M X Y)'
+ Like `div' but represents unsigned division.
+
+`(mod:M X Y)'
+`(umod:M X Y)'
+ Like `div' and `udiv' but represent the remainder instead of the
+ quotient.
+
+`(smin:M X Y)'
+`(smax:M X Y)'
+ Represents the smaller (for `smin') or larger (for `smax') of X
+ and Y, interpreted as signed integers in mode M.
+
+`(umin:M X Y)'
+`(umax:M X Y)'
+ Like `smin' and `smax', but the values are interpreted as unsigned
+ integers.
+
+`(not:M X)'
+ Represents the bitwise complement of the value represented by X,
+ carried out in mode M, which must be a fixed-point machine mode.
+
+`(and:M X Y)'
+ Represents the bitwise logical-and of the values represented by X
+ and Y, carried out in machine mode M, which must be a fixed-point
+ machine mode.
+
+`(ior:M X Y)'
+ Represents the bitwise inclusive-or of the values represented by X
+ and Y, carried out in machine mode M, which must be a fixed-point
+ mode.
+
+`(xor:M X Y)'
+ Represents the bitwise exclusive-or of the values represented by X
+ and Y, carried out in machine mode M, which must be a fixed-point
+ mode.
+
+`(ashift:M X C)'
+ Represents the result of arithmetically shifting X left by C
+ places. X have mode M, a fixed-point machine mode. C be a
+ fixed-point mode or be a constant with mode `VOIDmode'; which mode
+ is determined by the mode called for in the machine description
+ entry for the left-shift instruction. For example, on the VAX,
+ the mode of C is `QImode' regardless of M.
+
+`(lshiftrt:M X C)'
+`(ashiftrt:M X C)'
+ Like `ashift' but for right shift. Unlike the case for left shift,
+ these two operations are distinct.
+
+`(rotate:M X C)'
+`(rotatert:M X C)'
+ Similar but represent left and right rotate. If C is a constant,
+ use `rotate'.
+
+`(abs:M X)'
+ Represents the absolute value of X, computed in mode M.
+
+`(sqrt:M X)'
+ Represents the square root of X, computed in mode M. Most often M
+ will be a floating point mode.
+
+`(ffs:M X)'
+ Represents one plus the index of the least significant 1-bit in X,
+ represented as an integer of mode M. (The value is zero if X is
+ zero.) The mode of X need not be M; depending on the target
+ machine, various mode combinations may be valid.
+
+\1f
+File: gccint.info, Node: Comparisons, Next: Bit-Fields, Prev: Arithmetic, Up: RTL
+
+8.9 Comparison Operations
+=========================
+
+Comparison operators test a relation on two operands and are considered
+to represent a machine-dependent nonzero value described by, but not
+necessarily equal to, `STORE_FLAG_VALUE' (*note Misc::) if the relation
+holds, or zero if it does not. The mode of the comparison operation is
+independent of the mode of the data being compared. If the comparison
+operation is being tested (e.g., the first operand of an
+`if_then_else'), the mode must be `VOIDmode'. If the comparison
+operation is producing data to be stored in some variable, the mode
+must be in class `MODE_INT'. All comparison operations producing data
+must use the same mode, which is machine-specific.
+
+ There are two ways that comparison operations may be used. The
+comparison operators may be used to compare the condition codes `(cc0)'
+against zero, as in `(eq (cc0) (const_int 0))'. Such a construct
+actually refers to the result of the preceding instruction in which the
+condition codes were set. The instruction setting the condition code
+must be adjacent to the instruction using the condition code; only
+`note' insns may separate them.
+
+ Alternatively, a comparison operation may directly compare two data
+objects. The mode of the comparison is determined by the operands; they
+must both be valid for a common machine mode. A comparison with both
+operands constant would be invalid as the machine mode could not be
+deduced from it, but such a comparison should never exist in RTL due to
+constant folding.
+
+ In the example above, if `(cc0)' were last set to `(compare X Y)',
+the comparison operation is identical to `(eq X Y)'. Usually only one
+style of comparisons is supported on a particular machine, but the
+combine pass will try to merge the operations to produce the `eq' shown
+in case it exists in the context of the particular insn involved.
+
+ Inequality comparisons come in two flavors, signed and unsigned.
+Thus, there are distinct expression codes `gt' and `gtu' for signed and
+unsigned greater-than. These can produce different results for the same
+pair of integer values: for example, 1 is signed greater-than -1 but not
+unsigned greater-than, because -1 when regarded as unsigned is actually
+`0xffffffff' which is greater than 1.
+
+ The signed comparisons are also used for floating point values.
+Floating point comparisons are distinguished by the machine modes of
+the operands.
+
+`(eq:M X Y)'
+ `STORE_FLAG_VALUE' if the values represented by X and Y are equal,
+ otherwise 0.
+
+`(ne:M X Y)'
+ `STORE_FLAG_VALUE' if the values represented by X and Y are not
+ equal, otherwise 0.
+
+`(gt:M X Y)'
+ `STORE_FLAG_VALUE' if the X is greater than Y. If they are
+ fixed-point, the comparison is done in a signed sense.
+
+`(gtu:M X Y)'
+ Like `gt' but does unsigned comparison, on fixed-point numbers
+ only.
+
+`(lt:M X Y)'
+`(ltu:M X Y)'
+ Like `gt' and `gtu' but test for "less than".
+
+`(ge:M X Y)'
+`(geu:M X Y)'
+ Like `gt' and `gtu' but test for "greater than or equal".
+
+`(le:M X Y)'
+`(leu:M X Y)'
+ Like `gt' and `gtu' but test for "less than or equal".
+
+`(if_then_else COND THEN ELSE)'
+ This is not a comparison operation but is listed here because it is
+ always used in conjunction with a comparison operation. To be
+ precise, COND is a comparison expression. This expression
+ represents a choice, according to COND, between the value
+ represented by THEN and the one represented by ELSE.
+
+ On most machines, `if_then_else' expressions are valid only to
+ express conditional jumps.
+
+`(cond [TEST1 VALUE1 TEST2 VALUE2 ...] DEFAULT)'
+ Similar to `if_then_else', but more general. Each of TEST1,
+ TEST2, ... is performed in turn. The result of this expression is
+ the VALUE corresponding to the first nonzero test, or DEFAULT if
+ none of the tests are nonzero expressions.
+
+ This is currently not valid for instruction patterns and is
+ supported only for insn attributes. *Note Insn Attributes::.
+
+\1f
+File: gccint.info, Node: Bit-Fields, Next: Vector Operations, Prev: Comparisons, Up: RTL
+
+8.10 Bit-Fields
+===============
+
+Special expression codes exist to represent bit-field instructions.
+These types of expressions are lvalues in RTL; they may appear on the
+left side of an assignment, indicating insertion of a value into the
+specified bit-field.
+
+`(sign_extract:M LOC SIZE POS)'
+ This represents a reference to a sign-extended bit-field contained
+ or starting in LOC (a memory or register reference). The bit-field
+ is SIZE bits wide and starts at bit POS. The compilation option
+ `BITS_BIG_ENDIAN' says which end of the memory unit POS counts
+ from.
+
+ If LOC is in memory, its mode must be a single-byte integer mode.
+ If LOC is in a register, the mode to use is specified by the
+ operand of the `insv' or `extv' pattern (*note Standard Names::)
+ and is usually a full-word integer mode, which is the default if
+ none is specified.
+
+ The mode of POS is machine-specific and is also specified in the
+ `insv' or `extv' pattern.
+
+ The mode M is the same as the mode that would be used for LOC if
+ it were a register.
+
+`(zero_extract:M LOC SIZE POS)'
+ Like `sign_extract' but refers to an unsigned or zero-extended
+ bit-field. The same sequence of bits are extracted, but they are
+ filled to an entire word with zeros instead of by sign-extension.
+
+\1f
+File: gccint.info, Node: Vector Operations, Next: Conversions, Prev: Bit-Fields, Up: RTL
+
+8.11 Vector Operations
+======================
+
+All normal RTL expressions can be used with vector modes; they are
+interpreted as operating on each part of the vector independently.
+Additionally, there are a few new expressions to describe specific
+vector operations.
+
+`(vec_merge:M VEC1 VEC2 ITEMS)'
+ This describes a merge operation between two vectors. The result
+ is a vector of mode M; its elements are selected from either VEC1
+ or VEC2. Which elements are selected is described by ITEMS, which
+ is a bit mask represented by a `const_int'; a zero bit indicates
+ the corresponding element in the result vector is taken from VEC2
+ while a set bit indicates it is taken from VEC1.
+
+`(vec_select:M VEC1 SELECTION)'
+ This describes an operation that selects parts of a vector. VEC1
+ is the source vector, SELECTION is a `parallel' that contains a
+ `const_int' for each of the subparts of the result vector, giving
+ the number of the source subpart that should be stored into it.
+
+`(vec_concat:M VEC1 VEC2)'
+ Describes a vector concat operation. The result is a
+ concatenation of the vectors VEC1 and VEC2; its length is the sum
+ of the lengths of the two inputs.
+
+`(vec_const:M SUBPARTS)'
+ This describes a constant vector. SUBPARTS is a `parallel' that
+ contains a constant for each of the subparts of the vector.
+
+`(vec_duplicate:M VEC)'
+ This operation converts a small vector into a larger one by
+ duplicating the input values. The output vector mode must have
+ the same submodes as the input vector mode, and the number of
+ output parts must be an integer multiple of the number of input
+ parts.
+
+
+\1f
+File: gccint.info, Node: Conversions, Next: RTL Declarations, Prev: Vector Operations, Up: RTL
+
+8.12 Conversions
+================
+
+All conversions between machine modes must be represented by explicit
+conversion operations. For example, an expression which is the sum of
+a byte and a full word cannot be written as `(plus:SI (reg:QI 34)
+(reg:SI 80))' because the `plus' operation requires two operands of the
+same machine mode. Therefore, the byte-sized operand is enclosed in a
+conversion operation, as in
+
+ (plus:SI (sign_extend:SI (reg:QI 34)) (reg:SI 80))
+
+ The conversion operation is not a mere placeholder, because there
+may be more than one way of converting from a given starting mode to
+the desired final mode. The conversion operation code says how to do
+it.
+
+ For all conversion operations, X must not be `VOIDmode' because the
+mode in which to do the conversion would not be known. The conversion
+must either be done at compile-time or X must be placed into a register.
+
+`(sign_extend:M X)'
+ Represents the result of sign-extending the value X to machine
+ mode M. M must be a fixed-point mode and X a fixed-point value of
+ a mode narrower than M.
+
+`(zero_extend:M X)'
+ Represents the result of zero-extending the value X to machine
+ mode M. M must be a fixed-point mode and X a fixed-point value of
+ a mode narrower than M.
+
+`(float_extend:M X)'
+ Represents the result of extending the value X to machine mode M.
+ M must be a floating point mode and X a floating point value of a
+ mode narrower than M.
+
+`(truncate:M X)'
+ Represents the result of truncating the value X to machine mode M.
+ M must be a fixed-point mode and X a fixed-point value of a mode
+ wider than M.
+
+`(ss_truncate:M X)'
+ Represents the result of truncating the value X to machine mode M,
+ using signed saturation in the case of overflow. Both M and the
+ mode of X must be fixed-point modes.
+
+`(us_truncate:M X)'
+ Represents the result of truncating the value X to machine mode M,
+ using unsigned saturation in the case of overflow. Both M and the
+ mode of X must be fixed-point modes.
+
+`(float_truncate:M X)'
+ Represents the result of truncating the value X to machine mode M.
+ M must be a floating point mode and X a floating point value of a
+ mode wider than M.
+
+`(float:M X)'
+ Represents the result of converting fixed point value X, regarded
+ as signed, to floating point mode M.
+
+`(unsigned_float:M X)'
+ Represents the result of converting fixed point value X, regarded
+ as unsigned, to floating point mode M.
+
+`(fix:M X)'
+ When M is a fixed point mode, represents the result of converting
+ floating point value X to mode M, regarded as signed. How
+ rounding is done is not specified, so this operation may be used
+ validly in compiling C code only for integer-valued operands.
+
+`(unsigned_fix:M X)'
+ Represents the result of converting floating point value X to
+ fixed point mode M, regarded as unsigned. How rounding is done is
+ not specified.
+
+`(fix:M X)'
+ When M is a floating point mode, represents the result of
+ converting floating point value X (valid for mode M) to an
+ integer, still represented in floating point mode M, by rounding
+ towards zero.
+
+\1f
+File: gccint.info, Node: RTL Declarations, Next: Side Effects, Prev: Conversions, Up: RTL
+
+8.13 Declarations
+=================
+
+Declaration expression codes do not represent arithmetic operations but
+rather state assertions about their operands.
+
+`(strict_low_part (subreg:M (reg:N R) 0))'
+ This expression code is used in only one context: as the
+ destination operand of a `set' expression. In addition, the
+ operand of this expression must be a non-paradoxical `subreg'
+ expression.
+
+ The presence of `strict_low_part' says that the part of the
+ register which is meaningful in mode N, but is not part of mode M,
+ is not to be altered. Normally, an assignment to such a subreg is
+ allowed to have undefined effects on the rest of the register when
+ M is less than a word.
+
+\1f
+File: gccint.info, Node: Side Effects, Next: Incdec, Prev: RTL Declarations, Up: RTL
+
+8.14 Side Effect Expressions
+============================
+
+The expression codes described so far represent values, not actions.
+But machine instructions never produce values; they are meaningful only
+for their side effects on the state of the machine. Special expression
+codes are used to represent side effects.
+
+ The body of an instruction is always one of these side effect codes;
+the codes described above, which represent values, appear only as the
+operands of these.
+
+`(set LVAL X)'
+ Represents the action of storing the value of X into the place
+ represented by LVAL. LVAL must be an expression representing a
+ place that can be stored in: `reg' (or `subreg' or
+ `strict_low_part'), `mem', `pc', `parallel', or `cc0'.
+
+ If LVAL is a `reg', `subreg' or `mem', it has a machine mode; then
+ X must be valid for that mode.
+
+ If LVAL is a `reg' whose machine mode is less than the full width
+ of the register, then it means that the part of the register
+ specified by the machine mode is given the specified value and the
+ rest of the register receives an undefined value. Likewise, if
+ LVAL is a `subreg' whose machine mode is narrower than the mode of
+ the register, the rest of the register can be changed in an
+ undefined way.
+
+ If LVAL is a `strict_low_part' of a `subreg', then the part of the
+ register specified by the machine mode of the `subreg' is given
+ the value X and the rest of the register is not changed.
+
+ If LVAL is `(cc0)', it has no machine mode, and X may be either a
+ `compare' expression or a value that may have any mode. The
+ latter case represents a "test" instruction. The expression `(set
+ (cc0) (reg:M N))' is equivalent to `(set (cc0) (compare (reg:M N)
+ (const_int 0)))'. Use the former expression to save space during
+ the compilation.
+
+ If LVAL is a `parallel', it is used to represent the case of a
+ function returning a structure in multiple registers. Each element
+ of the `parallel' is an `expr_list' whose first operand is a `reg'
+ and whose second operand is a `const_int' representing the offset
+ (in bytes) into the structure at which the data in that register
+ corresponds. The first element may be null to indicate that the
+ structure is also passed partly in memory.
+
+ If LVAL is `(pc)', we have a jump instruction, and the
+ possibilities for X are very limited. It may be a `label_ref'
+ expression (unconditional jump). It may be an `if_then_else'
+ (conditional jump), in which case either the second or the third
+ operand must be `(pc)' (for the case which does not jump) and the
+ other of the two must be a `label_ref' (for the case which does
+ jump). X may also be a `mem' or `(plus:SI (pc) Y)', where Y may
+ be a `reg' or a `mem'; these unusual patterns are used to
+ represent jumps through branch tables.
+
+ If LVAL is neither `(cc0)' nor `(pc)', the mode of LVAL must not
+ be `VOIDmode' and the mode of X must be valid for the mode of LVAL.
+
+ LVAL is customarily accessed with the `SET_DEST' macro and X with
+ the `SET_SRC' macro.
+
+`(return)'
+ As the sole expression in a pattern, represents a return from the
+ current function, on machines where this can be done with one
+ instruction, such as VAXen. On machines where a multi-instruction
+ "epilogue" must be executed in order to return from the function,
+ returning is done by jumping to a label which precedes the
+ epilogue, and the `return' expression code is never used.
+
+ Inside an `if_then_else' expression, represents the value to be
+ placed in `pc' to return to the caller.
+
+ Note that an insn pattern of `(return)' is logically equivalent to
+ `(set (pc) (return))', but the latter form is never used.
+
+`(call FUNCTION NARGS)'
+ Represents a function call. FUNCTION is a `mem' expression whose
+ address is the address of the function to be called. NARGS is an
+ expression which can be used for two purposes: on some machines it
+ represents the number of bytes of stack argument; on others, it
+ represents the number of argument registers.
+
+ Each machine has a standard machine mode which FUNCTION must have.
+ The machine description defines macro `FUNCTION_MODE' to expand
+ into the requisite mode name. The purpose of this mode is to
+ specify what kind of addressing is allowed, on machines where the
+ allowed kinds of addressing depend on the machine mode being
+ addressed.
+
+`(clobber X)'
+ Represents the storing or possible storing of an unpredictable,
+ undescribed value into X, which must be a `reg', `scratch',
+ `parallel' or `mem' expression.
+
+ One place this is used is in string instructions that store
+ standard values into particular hard registers. It may not be
+ worth the trouble to describe the values that are stored, but it
+ is essential to inform the compiler that the registers will be
+ altered, lest it attempt to keep data in them across the string
+ instruction.
+
+ If X is `(mem:BLK (const_int 0))', it means that all memory
+ locations must be presumed clobbered. If X is a `parallel', it
+ has the same meaning as a `parallel' in a `set' expression.
+
+ Note that the machine description classifies certain hard
+ registers as "call-clobbered". All function call instructions are
+ assumed by default to clobber these registers, so there is no need
+ to use `clobber' expressions to indicate this fact. Also, each
+ function call is assumed to have the potential to alter any memory
+ location, unless the function is declared `const'.
+
+ If the last group of expressions in a `parallel' are each a
+ `clobber' expression whose arguments are `reg' or `match_scratch'
+ (*note RTL Template::) expressions, the combiner phase can add the
+ appropriate `clobber' expressions to an insn it has constructed
+ when doing so will cause a pattern to be matched.
+
+ This feature can be used, for example, on a machine that whose
+ multiply and add instructions don't use an MQ register but which
+ has an add-accumulate instruction that does clobber the MQ
+ register. Similarly, a combined instruction might require a
+ temporary register while the constituent instructions might not.
+
+ When a `clobber' expression for a register appears inside a
+ `parallel' with other side effects, the register allocator
+ guarantees that the register is unoccupied both before and after
+ that insn. However, the reload phase may allocate a register used
+ for one of the inputs unless the `&' constraint is specified for
+ the selected alternative (*note Modifiers::). You can clobber
+ either a specific hard register, a pseudo register, or a `scratch'
+ expression; in the latter two cases, GCC will allocate a hard
+ register that is available there for use as a temporary.
+
+ For instructions that require a temporary register, you should use
+ `scratch' instead of a pseudo-register because this will allow the
+ combiner phase to add the `clobber' when required. You do this by
+ coding (`clobber' (`match_scratch' ...)). If you do clobber a
+ pseudo register, use one which appears nowhere else--generate a
+ new one each time. Otherwise, you may confuse CSE.
+
+ There is one other known use for clobbering a pseudo register in a
+ `parallel': when one of the input operands of the insn is also
+ clobbered by the insn. In this case, using the same pseudo
+ register in the clobber and elsewhere in the insn produces the
+ expected results.
+
+`(use X)'
+ Represents the use of the value of X. It indicates that the value
+ in X at this point in the program is needed, even though it may
+ not be apparent why this is so. Therefore, the compiler will not
+ attempt to delete previous instructions whose only effect is to
+ store a value in X. X must be a `reg' expression.
+
+ In some situations, it may be tempting to add a `use' of a
+ register in a `parallel' to describe a situation where the value
+ of a special register will modify the behavior of the instruction.
+ An hypothetical example might be a pattern for an addition that can
+ either wrap around or use saturating addition depending on the
+ value of a special control register:
+
+ (parallel [(set (reg:SI 2) (unspec:SI [(reg:SI 3)
+ (reg:SI 4)] 0))
+ (use (reg:SI 1))])
+
+ This will not work, several of the optimizers only look at
+ expressions locally; it is very likely that if you have multiple
+ insns with identical inputs to the `unspec', they will be
+ optimized away even if register 1 changes in between.
+
+ This means that `use' can _only_ be used to describe that the
+ register is live. You should think twice before adding `use'
+ statements, more often you will want to use `unspec' instead. The
+ `use' RTX is most commonly useful to describe that a fixed
+ register is implicitly used in an insn. It is also safe to use in
+ patterns where the compiler knows for other reasons that the result
+ of the whole pattern is variable, such as `movstrM' or `call'
+ patterns.
+
+ During the reload phase, an insn that has a `use' as pattern can
+ carry a reg_equal note. These `use' insns will be deleted before
+ the reload phase exits.
+
+ During the delayed branch scheduling phase, X may be an insn.
+ This indicates that X previously was located at this place in the
+ code and its data dependencies need to be taken into account.
+ These `use' insns will be deleted before the delayed branch
+ scheduling phase exits.
+
+`(parallel [X0 X1 ...])'
+ Represents several side effects performed in parallel. The square
+ brackets stand for a vector; the operand of `parallel' is a vector
+ of expressions. X0, X1 and so on are individual side effect
+ expressions--expressions of code `set', `call', `return',
+ `clobber' or `use'.
+
+ "In parallel" means that first all the values used in the
+ individual side-effects are computed, and second all the actual
+ side-effects are performed. For example,
+
+ (parallel [(set (reg:SI 1) (mem:SI (reg:SI 1)))
+ (set (mem:SI (reg:SI 1)) (reg:SI 1))])
+
+ says unambiguously that the values of hard register 1 and the
+ memory location addressed by it are interchanged. In both places
+ where `(reg:SI 1)' appears as a memory address it refers to the
+ value in register 1 _before_ the execution of the insn.
+
+ It follows that it is _incorrect_ to use `parallel' and expect the
+ result of one `set' to be available for the next one. For
+ example, people sometimes attempt to represent a jump-if-zero
+ instruction this way:
+
+ (parallel [(set (cc0) (reg:SI 34))
+ (set (pc) (if_then_else
+ (eq (cc0) (const_int 0))
+ (label_ref ...)
+ (pc)))])
+
+ But this is incorrect, because it says that the jump condition
+ depends on the condition code value _before_ this instruction, not
+ on the new value that is set by this instruction.
+
+ Peephole optimization, which takes place together with final
+ assembly code output, can produce insns whose patterns consist of
+ a `parallel' whose elements are the operands needed to output the
+ resulting assembler code--often `reg', `mem' or constant
+ expressions. This would not be well-formed RTL at any other stage
+ in compilation, but it is ok then because no further optimization
+ remains to be done. However, the definition of the macro
+ `NOTICE_UPDATE_CC', if any, must deal with such insns if you
+ define any peephole optimizations.
+
+`(cond_exec [COND EXPR])'
+ Represents a conditionally executed expression. The EXPR is
+ executed only if the COND is nonzero. The COND expression must
+ not have side-effects, but the EXPR may very well have
+ side-effects.
+
+`(sequence [INSNS ...])'
+ Represents a sequence of insns. Each of the INSNS that appears in
+ the vector is suitable for appearing in the chain of insns, so it
+ must be an `insn', `jump_insn', `call_insn', `code_label',
+ `barrier' or `note'.
+
+ A `sequence' RTX is never placed in an actual insn during RTL
+ generation. It represents the sequence of insns that result from a
+ `define_expand' _before_ those insns are passed to `emit_insn' to
+ insert them in the chain of insns. When actually inserted, the
+ individual sub-insns are separated out and the `sequence' is
+ forgotten.
+
+ After delay-slot scheduling is completed, an insn and all the
+ insns that reside in its delay slots are grouped together into a
+ `sequence'. The insn requiring the delay slot is the first insn
+ in the vector; subsequent insns are to be placed in the delay slot.
+
+ `INSN_ANNULLED_BRANCH_P' is set on an insn in a delay slot to
+ indicate that a branch insn should be used that will conditionally
+ annul the effect of the insns in the delay slots. In such a case,
+ `INSN_FROM_TARGET_P' indicates that the insn is from the target of
+ the branch and should be executed only if the branch is taken;
+ otherwise the insn should be executed only if the branch is not
+ taken. *Note Delay Slots::.
+
+ These expression codes appear in place of a side effect, as the body
+of an insn, though strictly speaking they do not always describe side
+effects as such:
+
+`(asm_input S)'
+ Represents literal assembler code as described by the string S.
+
+`(unspec [OPERANDS ...] INDEX)'
+`(unspec_volatile [OPERANDS ...] INDEX)'
+ Represents a machine-specific operation on OPERANDS. INDEX
+ selects between multiple machine-specific operations.
+ `unspec_volatile' is used for volatile operations and operations
+ that may trap; `unspec' is used for other operations.
+
+ These codes may appear inside a `pattern' of an insn, inside a
+ `parallel', or inside an expression.
+
+`(addr_vec:M [LR0 LR1 ...])'
+ Represents a table of jump addresses. The vector elements LR0,
+ etc., are `label_ref' expressions. The mode M specifies how much
+ space is given to each address; normally M would be `Pmode'.
+
+`(addr_diff_vec:M BASE [LR0 LR1 ...] MIN MAX FLAGS)'
+ Represents a table of jump addresses expressed as offsets from
+ BASE. The vector elements LR0, etc., are `label_ref' expressions
+ and so is BASE. The mode M specifies how much space is given to
+ each address-difference. MIN and MAX are set up by branch
+ shortening and hold a label with a minimum and a maximum address,
+ respectively. FLAGS indicates the relative position of BASE, MIN
+ and MAX to the containing insn and of MIN and MAX to BASE. See
+ rtl.def for details.
+
+`(prefetch:M ADDR RW LOCALITY)'
+ Represents prefetch of memory at address ADDR. Operand RW is 1 if
+ the prefetch is for data to be written, 0 otherwise; targets that
+ do not support write prefetches should treat this as a normal
+ prefetch. Operand LOCALITY specifies the amount of temporal
+ locality; 0 if there is none or 1, 2, or 3 for increasing levels
+ of temporal locality; targets that do not support locality hints
+ should ignore this.
+
+ This insn is used to minimize cache-miss latency by moving data
+ into a cache before it is accessed. It should use only
+ non-faulting data prefetch instructions.
+
+\1f
+File: gccint.info, Node: Incdec, Next: Assembler, Prev: Side Effects, Up: RTL
+
+8.15 Embedded Side-Effects on Addresses
+=======================================
+
+Six special side-effect expression codes appear as memory addresses.
+
+`(pre_dec:M X)'
+ Represents the side effect of decrementing X by a standard amount
+ and represents also the value that X has after being decremented.
+ X must be a `reg' or `mem', but most machines allow only a `reg'.
+ M must be the machine mode for pointers on the machine in use.
+ The amount X is decremented by is the length in bytes of the
+ machine mode of the containing memory reference of which this
+ expression serves as the address. Here is an example of its use:
+
+ (mem:DF (pre_dec:SI (reg:SI 39)))
+
+ This says to decrement pseudo register 39 by the length of a
+ `DFmode' value and use the result to address a `DFmode' value.
+
+`(pre_inc:M X)'
+ Similar, but specifies incrementing X instead of decrementing it.
+
+`(post_dec:M X)'
+ Represents the same side effect as `pre_dec' but a different
+ value. The value represented here is the value X has before being
+ decremented.
+
+`(post_inc:M X)'
+ Similar, but specifies incrementing X instead of decrementing it.
+
+`(post_modify:M X Y)'
+ Represents the side effect of setting X to Y and represents X
+ before X is modified. X must be a `reg' or `mem', but most
+ machines allow only a `reg'. M must be the machine mode for
+ pointers on the machine in use. The amount X is decremented by is
+ the length in bytes of the machine mode of the containing memory
+ reference of which this expression serves as the address. Note
+ that this is not currently implemented.
+
+ The expression Y must be one of three forms:
+ `(plus:M X Z)', `(minus:M X Z)', or `(plus:M X I)',
+ where Z is an index register and I is a constant.
+
+ Here is an example of its use:
+
+ (mem:SF (post_modify:SI (reg:SI 42) (plus (reg:SI 42)
+ (reg:SI 48))))
+
+ This says to modify pseudo register 42 by adding the contents of
+ pseudo register 48 to it, after the use of what ever 42 points to.
+
+`(pre_modify:M X EXPR)'
+ Similar except side effects happen before the use.
+
+ These embedded side effect expressions must be used with care.
+Instruction patterns may not use them. Until the `flow' pass of the
+compiler, they may occur only to represent pushes onto the stack. The
+`flow' pass finds cases where registers are incremented or decremented
+in one instruction and used as an address shortly before or after;
+these cases are then transformed to use pre- or post-increment or
+-decrement.
+
+ If a register used as the operand of these expressions is used in
+another address in an insn, the original value of the register is used.
+Uses of the register outside of an address are not permitted within the
+same insn as a use in an embedded side effect expression because such
+insns behave differently on different machines and hence must be treated
+as ambiguous and disallowed.
+
+ An instruction that can be represented with an embedded side effect
+could also be represented using `parallel' containing an additional
+`set' to describe how the address register is altered. This is not
+done because machines that allow these operations at all typically
+allow them wherever a memory address is called for. Describing them as
+additional parallel stores would require doubling the number of entries
+in the machine description.
+
+\1f
+File: gccint.info, Node: Assembler, Next: Insns, Prev: Incdec, Up: RTL
+
+8.16 Assembler Instructions as Expressions
+==========================================
+
+The RTX code `asm_operands' represents a value produced by a
+user-specified assembler instruction. It is used to represent an `asm'
+statement with arguments. An `asm' statement with a single output
+operand, like this:
+
+ asm ("foo %1,%2,%0" : "=a" (outputvar) : "g" (x + y), "di" (*z));
+
+is represented using a single `asm_operands' RTX which represents the
+value that is stored in `outputvar':
+
+ (set RTX-FOR-OUTPUTVAR
+ (asm_operands "foo %1,%2,%0" "a" 0
+ [RTX-FOR-ADDITION-RESULT RTX-FOR-*Z]
+ [(asm_input:M1 "g")
+ (asm_input:M2 "di")]))
+
+Here the operands of the `asm_operands' RTX are the assembler template
+string, the output-operand's constraint, the index-number of the output
+operand among the output operands specified, a vector of input operand
+RTX's, and a vector of input-operand modes and constraints. The mode
+M1 is the mode of the sum `x+y'; M2 is that of `*z'.
+
+ When an `asm' statement has multiple output values, its insn has
+several such `set' RTX's inside of a `parallel'. Each `set' contains a
+`asm_operands'; all of these share the same assembler template and
+vectors, but each contains the constraint for the respective output
+operand. They are also distinguished by the output-operand index
+number, which is 0, 1, ... for successive output operands.
+
+\1f
+File: gccint.info, Node: Insns, Next: Calls, Prev: Assembler, Up: RTL
+
+8.17 Insns
+==========
+
+The RTL representation of the code for a function is a doubly-linked
+chain of objects called "insns". Insns are expressions with special
+codes that are used for no other purpose. Some insns are actual
+instructions; others represent dispatch tables for `switch' statements;
+others represent labels to jump to or various sorts of declarative
+information.
+
+ In addition to its own specific data, each insn must have a unique
+id-number that distinguishes it from all other insns in the current
+function (after delayed branch scheduling, copies of an insn with the
+same id-number may be present in multiple places in a function, but
+these copies will always be identical and will only appear inside a
+`sequence'), and chain pointers to the preceding and following insns.
+These three fields occupy the same position in every insn, independent
+of the expression code of the insn. They could be accessed with `XEXP'
+and `XINT', but instead three special macros are always used:
+
+`INSN_UID (I)'
+ Accesses the unique id of insn I.
+
+`PREV_INSN (I)'
+ Accesses the chain pointer to the insn preceding I. If I is the
+ first insn, this is a null pointer.
+
+`NEXT_INSN (I)'
+ Accesses the chain pointer to the insn following I. If I is the
+ last insn, this is a null pointer.
+
+ The first insn in the chain is obtained by calling `get_insns'; the
+last insn is the result of calling `get_last_insn'. Within the chain
+delimited by these insns, the `NEXT_INSN' and `PREV_INSN' pointers must
+always correspond: if INSN is not the first insn,
+
+ NEXT_INSN (PREV_INSN (INSN)) == INSN
+
+is always true and if INSN is not the last insn,
+
+ PREV_INSN (NEXT_INSN (INSN)) == INSN
+
+is always true.
+
+ After delay slot scheduling, some of the insns in the chain might be
+`sequence' expressions, which contain a vector of insns. The value of
+`NEXT_INSN' in all but the last of these insns is the next insn in the
+vector; the value of `NEXT_INSN' of the last insn in the vector is the
+same as the value of `NEXT_INSN' for the `sequence' in which it is
+contained. Similar rules apply for `PREV_INSN'.
+
+ This means that the above invariants are not necessarily true for
+insns inside `sequence' expressions. Specifically, if INSN is the
+first insn in a `sequence', `NEXT_INSN (PREV_INSN (INSN))' is the insn
+containing the `sequence' expression, as is the value of `PREV_INSN
+(NEXT_INSN (INSN))' if INSN is the last insn in the `sequence'
+expression. You can use these expressions to find the containing
+`sequence' expression.
+
+ Every insn has one of the following six expression codes:
+
+`insn'
+ The expression code `insn' is used for instructions that do not
+ jump and do not do function calls. `sequence' expressions are
+ always contained in insns with code `insn' even if one of those
+ insns should jump or do function calls.
+
+ Insns with code `insn' have four additional fields beyond the three
+ mandatory ones listed above. These four are described in a table
+ below.
+
+`jump_insn'
+ The expression code `jump_insn' is used for instructions that may
+ jump (or, more generally, may contain `label_ref' expressions). If
+ there is an instruction to return from the current function, it is
+ recorded as a `jump_insn'.
+
+ `jump_insn' insns have the same extra fields as `insn' insns,
+ accessed in the same way and in addition contain a field
+ `JUMP_LABEL' which is defined once jump optimization has completed.
+
+ For simple conditional and unconditional jumps, this field contains
+ the `code_label' to which this insn will (possibly conditionally)
+ branch. In a more complex jump, `JUMP_LABEL' records one of the
+ labels that the insn refers to; the only way to find the others is
+ to scan the entire body of the insn. In an `addr_vec',
+ `JUMP_LABEL' is `NULL_RTX'.
+
+ Return insns count as jumps, but since they do not refer to any
+ labels, their `JUMP_LABEL' is `NULL_RTX'.
+
+`call_insn'
+ The expression code `call_insn' is used for instructions that may
+ do function calls. It is important to distinguish these
+ instructions because they imply that certain registers and memory
+ locations may be altered unpredictably.
+
+ `call_insn' insns have the same extra fields as `insn' insns,
+ accessed in the same way and in addition contain a field
+ `CALL_INSN_FUNCTION_USAGE', which contains a list (chain of
+ `expr_list' expressions) containing `use' and `clobber'
+ expressions that denote hard registers and `MEM's used or
+ clobbered by the called function.
+
+ A `MEM' generally points to a stack slots in which arguments passed
+ to the libcall by reference (*note FUNCTION_ARG_PASS_BY_REFERENCE:
+ Register Arguments.) are stored. If the argument is caller-copied
+ (*note FUNCTION_ARG_CALLEE_COPIES: Register Arguments.), the stack
+ slot will be mentioned in `CLOBBER' and `USE' entries; if it's
+ callee-copied, only a `USE' will appear, and the `MEM' may point
+ to addresses that are not stack slots. These `MEM's are used only
+ in libcalls, because, unlike regular function calls, `CONST_CALL's
+ (which libcalls generally are, *note CONST_CALL_P: Flags.) aren't
+ assumed to read and write all memory, so flow would consider the
+ stores dead and remove them. Note that, since a libcall must
+ never return values in memory (*note RETURN_IN_MEMORY: Aggregate
+ Return.), there will never be a `CLOBBER' for a memory address
+ holding a return value.
+
+ `CLOBBER'ed registers in this list augment registers specified in
+ `CALL_USED_REGISTERS' (*note Register Basics::).
+
+`code_label'
+ A `code_label' insn represents a label that a jump insn can jump
+ to. It contains two special fields of data in addition to the
+ three standard ones. `CODE_LABEL_NUMBER' is used to hold the
+ "label number", a number that identifies this label uniquely among
+ all the labels in the compilation (not just in the current
+ function). Ultimately, the label is represented in the assembler
+ output as an assembler label, usually of the form `LN' where N is
+ the label number.
+
+ When a `code_label' appears in an RTL expression, it normally
+ appears within a `label_ref' which represents the address of the
+ label, as a number.
+
+ Besides as a `code_label', a label can also be represented as a
+ `note' of type `NOTE_INSN_DELETED_LABEL'.
+
+ The field `LABEL_NUSES' is only defined once the jump optimization
+ phase is completed and contains the number of times this label is
+ referenced in the current function.
+
+ The field `LABEL_ALTERNATE_NAME' is used to associate a name with
+ a `code_label'. If this field is defined, the alternate name will
+ be emitted instead of an internally generated label name.
+
+`barrier'
+ Barriers are placed in the instruction stream when control cannot
+ flow past them. They are placed after unconditional jump
+ instructions to indicate that the jumps are unconditional and
+ after calls to `volatile' functions, which do not return (e.g.,
+ `exit'). They contain no information beyond the three standard
+ fields.
+
+`note'
+ `note' insns are used to represent additional debugging and
+ declarative information. They contain two nonstandard fields, an
+ integer which is accessed with the macro `NOTE_LINE_NUMBER' and a
+ string accessed with `NOTE_SOURCE_FILE'.
+
+ If `NOTE_LINE_NUMBER' is positive, the note represents the
+ position of a source line and `NOTE_SOURCE_FILE' is the source
+ file name that the line came from. These notes control generation
+ of line number data in the assembler output.
+
+ Otherwise, `NOTE_LINE_NUMBER' is not really a line number but a
+ code with one of the following values (and `NOTE_SOURCE_FILE' must
+ contain a null pointer):
+
+ `NOTE_INSN_DELETED'
+ Such a note is completely ignorable. Some passes of the
+ compiler delete insns by altering them into notes of this
+ kind.
+
+ `NOTE_INSN_DELETED_LABEL'
+ This marks what used to be a `code_label', but was not used
+ for other purposes than taking its address and was
+ transformed to mark that no code jumps to it.
+
+ `NOTE_INSN_BLOCK_BEG'
+ `NOTE_INSN_BLOCK_END'
+ These types of notes indicate the position of the beginning
+ and end of a level of scoping of variable names. They
+ control the output of debugging information.
+
+ `NOTE_INSN_EH_REGION_BEG'
+ `NOTE_INSN_EH_REGION_END'
+ These types of notes indicate the position of the beginning
+ and end of a level of scoping for exception handling.
+ `NOTE_BLOCK_NUMBER' identifies which `CODE_LABEL' or `note'
+ of type `NOTE_INSN_DELETED_LABEL' is associated with the
+ given region.
+
+ `NOTE_INSN_LOOP_BEG'
+ `NOTE_INSN_LOOP_END'
+ These types of notes indicate the position of the beginning
+ and end of a `while' or `for' loop. They enable the loop
+ optimizer to find loops quickly.
+
+ `NOTE_INSN_LOOP_CONT'
+ Appears at the place in a loop that `continue' statements
+ jump to.
+
+ `NOTE_INSN_LOOP_VTOP'
+ This note indicates the place in a loop where the exit test
+ begins for those loops in which the exit test has been
+ duplicated. This position becomes another virtual start of
+ the loop when considering loop invariants.
+
+ `NOTE_INSN_FUNCTION_END'
+ Appears near the end of the function body, just before the
+ label that `return' statements jump to (on machine where a
+ single instruction does not suffice for returning). This
+ note may be deleted by jump optimization.
+
+ `NOTE_INSN_SETJMP'
+ Appears following each call to `setjmp' or a related function.
+
+ These codes are printed symbolically when they appear in debugging
+ dumps.
+
+ The machine mode of an insn is normally `VOIDmode', but some phases
+use the mode for various purposes.
+
+ The common subexpression elimination pass sets the mode of an insn to
+`QImode' when it is the first insn in a block that has already been
+processed.
+
+ The second Haifa scheduling pass, for targets that can multiple
+issue, sets the mode of an insn to `TImode' when it is believed that the
+instruction begins an issue group. That is, when the instruction
+cannot issue simultaneously with the previous. This may be relied on
+by later passes, in particular machine-dependent reorg.
+
+ Here is a table of the extra fields of `insn', `jump_insn' and
+`call_insn' insns:
+
+`PATTERN (I)'
+ An expression for the side effect performed by this insn. This
+ must be one of the following codes: `set', `call', `use',
+ `clobber', `return', `asm_input', `asm_output', `addr_vec',
+ `addr_diff_vec', `trap_if', `unspec', `unspec_volatile',
+ `parallel', `cond_exec', or `sequence'. If it is a `parallel',
+ each element of the `parallel' must be one these codes, except that
+ `parallel' expressions cannot be nested and `addr_vec' and
+ `addr_diff_vec' are not permitted inside a `parallel' expression.
+
+`INSN_CODE (I)'
+ An integer that says which pattern in the machine description
+ matches this insn, or -1 if the matching has not yet been
+ attempted.
+
+ Such matching is never attempted and this field remains -1 on an
+ insn whose pattern consists of a single `use', `clobber',
+ `asm_input', `addr_vec' or `addr_diff_vec' expression.
+
+ Matching is also never attempted on insns that result from an `asm'
+ statement. These contain at least one `asm_operands' expression.
+ The function `asm_noperands' returns a non-negative value for such
+ insns.
+
+ In the debugging output, this field is printed as a number
+ followed by a symbolic representation that locates the pattern in
+ the `md' file as some small positive or negative offset from a
+ named pattern.
+
+`LOG_LINKS (I)'
+ A list (chain of `insn_list' expressions) giving information about
+ dependencies between instructions within a basic block. Neither a
+ jump nor a label may come between the related insns.
+
+`REG_NOTES (I)'
+ A list (chain of `expr_list' and `insn_list' expressions) giving
+ miscellaneous information about the insn. It is often information
+ pertaining to the registers used in this insn.
+
+ The `LOG_LINKS' field of an insn is a chain of `insn_list'
+expressions. Each of these has two operands: the first is an insn, and
+the second is another `insn_list' expression (the next one in the
+chain). The last `insn_list' in the chain has a null pointer as second
+operand. The significant thing about the chain is which insns appear
+in it (as first operands of `insn_list' expressions). Their order is
+not significant.
+
+ This list is originally set up by the flow analysis pass; it is a
+null pointer until then. Flow only adds links for those data
+dependencies which can be used for instruction combination. For each
+insn, the flow analysis pass adds a link to insns which store into
+registers values that are used for the first time in this insn. The
+instruction scheduling pass adds extra links so that every dependence
+will be represented. Links represent data dependencies,
+antidependencies and output dependencies; the machine mode of the link
+distinguishes these three types: antidependencies have mode
+`REG_DEP_ANTI', output dependencies have mode `REG_DEP_OUTPUT', and
+data dependencies have mode `VOIDmode'.
+
+ The `REG_NOTES' field of an insn is a chain similar to the
+`LOG_LINKS' field but it includes `expr_list' expressions in addition
+to `insn_list' expressions. There are several kinds of register notes,
+which are distinguished by the machine mode, which in a register note
+is really understood as being an `enum reg_note'. The first operand OP
+of the note is data whose meaning depends on the kind of note.
+
+ The macro `REG_NOTE_KIND (X)' returns the kind of register note.
+Its counterpart, the macro `PUT_REG_NOTE_KIND (X, NEWKIND)' sets the
+register note type of X to be NEWKIND.
+
+ Register notes are of three classes: They may say something about an
+input to an insn, they may say something about an output of an insn, or
+they may create a linkage between two insns. There are also a set of
+values that are only used in `LOG_LINKS'.
+
+ These register notes annotate inputs to an insn:
+
+`REG_DEAD'
+ The value in OP dies in this insn; that is to say, altering the
+ value immediately after this insn would not affect the future
+ behavior of the program.
+
+ It does not follow that the register OP has no useful value after
+ this insn since OP is not necessarily modified by this insn.
+ Rather, no subsequent instruction uses the contents of OP.
+
+`REG_UNUSED'
+ The register OP being set by this insn will not be used in a
+ subsequent insn. This differs from a `REG_DEAD' note, which
+ indicates that the value in an input will not be used subsequently.
+ These two notes are independent; both may be present for the same
+ register.
+
+`REG_INC'
+ The register OP is incremented (or decremented; at this level
+ there is no distinction) by an embedded side effect inside this
+ insn. This means it appears in a `post_inc', `pre_inc',
+ `post_dec' or `pre_dec' expression.
+
+`REG_NONNEG'
+ The register OP is known to have a nonnegative value when this
+ insn is reached. This is used so that decrement and branch until
+ zero instructions, such as the m68k dbra, can be matched.
+
+ The `REG_NONNEG' note is added to insns only if the machine
+ description has a `decrement_and_branch_until_zero' pattern.
+
+`REG_NO_CONFLICT'
+ This insn does not cause a conflict between OP and the item being
+ set by this insn even though it might appear that it does. In
+ other words, if the destination register and OP could otherwise be
+ assigned the same register, this insn does not prevent that
+ assignment.
+
+ Insns with this note are usually part of a block that begins with a
+ `clobber' insn specifying a multi-word pseudo register (which will
+ be the output of the block), a group of insns that each set one
+ word of the value and have the `REG_NO_CONFLICT' note attached,
+ and a final insn that copies the output to itself with an attached
+ `REG_EQUAL' note giving the expression being computed. This block
+ is encapsulated with `REG_LIBCALL' and `REG_RETVAL' notes on the
+ first and last insns, respectively.
+
+`REG_LABEL'
+ This insn uses OP, a `code_label' or a `note' of type
+ `NOTE_INSN_DELETED_LABEL', but is not a `jump_insn', or it is a
+ `jump_insn' that required the label to be held in a register. The
+ presence of this note allows jump optimization to be aware that OP
+ is, in fact, being used, and flow optimization to build an
+ accurate flow graph.
+
+ The following notes describe attributes of outputs of an insn:
+
+`REG_EQUIV'
+`REG_EQUAL'
+ This note is only valid on an insn that sets only one register and
+ indicates that that register will be equal to OP at run time; the
+ scope of this equivalence differs between the two types of notes.
+ The value which the insn explicitly copies into the register may
+ look different from OP, but they will be equal at run time. If the
+ output of the single `set' is a `strict_low_part' expression, the
+ note refers to the register that is contained in `SUBREG_REG' of
+ the `subreg' expression.
+
+ For `REG_EQUIV', the register is equivalent to OP throughout the
+ entire function, and could validly be replaced in all its
+ occurrences by OP. ("Validly" here refers to the data flow of the
+ program; simple replacement may make some insns invalid.) For
+ example, when a constant is loaded into a register that is never
+ assigned any other value, this kind of note is used.
+
+ When a parameter is copied into a pseudo-register at entry to a
+ function, a note of this kind records that the register is
+ equivalent to the stack slot where the parameter was passed.
+ Although in this case the register may be set by other insns, it
+ is still valid to replace the register by the stack slot
+ throughout the function.
+
+ A `REG_EQUIV' note is also used on an instruction which copies a
+ register parameter into a pseudo-register at entry to a function,
+ if there is a stack slot where that parameter could be stored.
+ Although other insns may set the pseudo-register, it is valid for
+ the compiler to replace the pseudo-register by stack slot
+ throughout the function, provided the compiler ensures that the
+ stack slot is properly initialized by making the replacement in
+ the initial copy instruction as well. This is used on machines
+ for which the calling convention allocates stack space for
+ register parameters. See `REG_PARM_STACK_SPACE' in *note Stack
+ Arguments::.
+
+ In the case of `REG_EQUAL', the register that is set by this insn
+ will be equal to OP at run time at the end of this insn but not
+ necessarily elsewhere in the function. In this case, OP is
+ typically an arithmetic expression. For example, when a sequence
+ of insns such as a library call is used to perform an arithmetic
+ operation, this kind of note is attached to the insn that produces
+ or copies the final value.
+
+ These two notes are used in different ways by the compiler passes.
+ `REG_EQUAL' is used by passes prior to register allocation (such as
+ common subexpression elimination and loop optimization) to tell
+ them how to think of that value. `REG_EQUIV' notes are used by
+ register allocation to indicate that there is an available
+ substitute expression (either a constant or a `mem' expression for
+ the location of a parameter on the stack) that may be used in
+ place of a register if insufficient registers are available.
+
+ Except for stack homes for parameters, which are indicated by a
+ `REG_EQUIV' note and are not useful to the early optimization
+ passes and pseudo registers that are equivalent to a memory
+ location throughout their entire life, which is not detected until
+ later in the compilation, all equivalences are initially indicated
+ by an attached `REG_EQUAL' note. In the early stages of register
+ allocation, a `REG_EQUAL' note is changed into a `REG_EQUIV' note
+ if OP is a constant and the insn represents the only set of its
+ destination register.
+
+ Thus, compiler passes prior to register allocation need only check
+ for `REG_EQUAL' notes and passes subsequent to register allocation
+ need only check for `REG_EQUIV' notes.
+
+`REG_WAS_0'
+ The single output of this insn contained zero before this insn.
+ OP is the insn that set it to zero. You can rely on this note if
+ it is present and OP has not been deleted or turned into a `note';
+ its absence implies nothing.
+
+ These notes describe linkages between insns. They occur in pairs:
+one insn has one of a pair of notes that points to a second insn, which
+has the inverse note pointing back to the first insn.
+
+`REG_RETVAL'
+ This insn copies the value of a multi-insn sequence (for example, a
+ library call), and OP is the first insn of the sequence (for a
+ library call, the first insn that was generated to set up the
+ arguments for the library call).
+
+ Loop optimization uses this note to treat such a sequence as a
+ single operation for code motion purposes and flow analysis uses
+ this note to delete such sequences whose results are dead.
+
+ A `REG_EQUAL' note will also usually be attached to this insn to
+ provide the expression being computed by the sequence.
+
+ These notes will be deleted after reload, since they are no longer
+ accurate or useful.
+
+`REG_LIBCALL'
+ This is the inverse of `REG_RETVAL': it is placed on the first
+ insn of a multi-insn sequence, and it points to the last one.
+
+ These notes are deleted after reload, since they are no longer
+ useful or accurate.
+
+`REG_CC_SETTER'
+`REG_CC_USER'
+ On machines that use `cc0', the insns which set and use `cc0' set
+ and use `cc0' are adjacent. However, when branch delay slot
+ filling is done, this may no longer be true. In this case a
+ `REG_CC_USER' note will be placed on the insn setting `cc0' to
+ point to the insn using `cc0' and a `REG_CC_SETTER' note will be
+ placed on the insn using `cc0' to point to the insn setting `cc0'.
+
+ These values are only used in the `LOG_LINKS' field, and indicate
+the type of dependency that each link represents. Links which indicate
+a data dependence (a read after write dependence) do not use any code,
+they simply have mode `VOIDmode', and are printed without any
+descriptive text.
+
+`REG_DEP_ANTI'
+ This indicates an anti dependence (a write after read dependence).
+
+`REG_DEP_OUTPUT'
+ This indicates an output dependence (a write after write
+ dependence).
+
+ These notes describe information gathered from gcov profile data.
+They are stored in the `REG_NOTES' field of an insn as an `expr_list'.
+
+`REG_EXEC_COUNT'
+ This is used to indicate the number of times a basic block was
+ executed according to the profile data. The note is attached to
+ the first insn in the basic block.
+
+`REG_BR_PROB'
+ This is used to specify the ratio of branches to non-branches of a
+ branch insn according to the profile data. The value is stored as
+ a value between 0 and REG_BR_PROB_BASE; larger values indicate a
+ higher probability that the branch will be taken.
+
+`REG_BR_PRED'
+ These notes are found in JUMP insns after delayed branch scheduling
+ has taken place. They indicate both the direction and the
+ likelihood of the JUMP. The format is a bitmask of ATTR_FLAG_*
+ values.
+
+`REG_FRAME_RELATED_EXPR'
+ This is used on an RTX_FRAME_RELATED_P insn wherein the attached
+ expression is used in place of the actual insn pattern. This is
+ done in cases where the pattern is either complex or misleading.
+
+ For convenience, the machine mode in an `insn_list' or `expr_list'
+is printed using these symbolic codes in debugging dumps.
+
+ The only difference between the expression codes `insn_list' and
+`expr_list' is that the first operand of an `insn_list' is assumed to
+be an insn and is printed in debugging dumps as the insn's unique id;
+the first operand of an `expr_list' is printed in the ordinary way as
+an expression.
+
+\1f
+File: gccint.info, Node: Calls, Next: Sharing, Prev: Insns, Up: RTL
+
+8.18 RTL Representation of Function-Call Insns
+==============================================
+
+Insns that call subroutines have the RTL expression code `call_insn'.
+These insns must satisfy special rules, and their bodies must use a
+special RTL expression code, `call'.
+
+ A `call' expression has two operands, as follows:
+
+ (call (mem:FM ADDR) NBYTES)
+
+Here NBYTES is an operand that represents the number of bytes of
+argument data being passed to the subroutine, FM is a machine mode
+(which must equal as the definition of the `FUNCTION_MODE' macro in the
+machine description) and ADDR represents the address of the subroutine.
+
+ For a subroutine that returns no value, the `call' expression as
+shown above is the entire body of the insn, except that the insn might
+also contain `use' or `clobber' expressions.
+
+ For a subroutine that returns a value whose mode is not `BLKmode',
+the value is returned in a hard register. If this register's number is
+R, then the body of the call insn looks like this:
+
+ (set (reg:M R)
+ (call (mem:FM ADDR) NBYTES))
+
+This RTL expression makes it clear (to the optimizer passes) that the
+appropriate register receives a useful value in this insn.
+
+ When a subroutine returns a `BLKmode' value, it is handled by
+passing to the subroutine the address of a place to store the value.
+So the call insn itself does not "return" any value, and it has the
+same RTL form as a call that returns nothing.
+
+ On some machines, the call instruction itself clobbers some register,
+for example to contain the return address. `call_insn' insns on these
+machines should have a body which is a `parallel' that contains both
+the `call' expression and `clobber' expressions that indicate which
+registers are destroyed. Similarly, if the call instruction requires
+some register other than the stack pointer that is not explicitly
+mentioned it its RTL, a `use' subexpression should mention that
+register.
+
+ Functions that are called are assumed to modify all registers listed
+in the configuration macro `CALL_USED_REGISTERS' (*note Register
+Basics::) and, with the exception of `const' functions and library
+calls, to modify all of memory.
+
+ Insns containing just `use' expressions directly precede the
+`call_insn' insn to indicate which registers contain inputs to the
+function. Similarly, if registers other than those in
+`CALL_USED_REGISTERS' are clobbered by the called function, insns
+containing a single `clobber' follow immediately after the call to
+indicate which registers.
+
+\1f
+File: gccint.info, Node: Sharing, Next: Reading RTL, Prev: Calls, Up: RTL
+
+8.19 Structure Sharing Assumptions
+==================================
+
+The compiler assumes that certain kinds of RTL expressions are unique;
+there do not exist two distinct objects representing the same value.
+In other cases, it makes an opposite assumption: that no RTL expression
+object of a certain kind appears in more than one place in the
+containing structure.
+
+ These assumptions refer to a single function; except for the RTL
+objects that describe global variables and external functions, and a
+few standard objects such as small integer constants, no RTL objects
+are common to two functions.
+
+ * Each pseudo-register has only a single `reg' object to represent
+ it, and therefore only a single machine mode.
+
+ * For any symbolic label, there is only one `symbol_ref' object
+ referring to it.
+
+ * All `const_int' expressions with equal values are shared.
+
+ * There is only one `pc' expression.
+
+ * There is only one `cc0' expression.
+
+ * There is only one `const_double' expression with value 0 for each
+ floating point mode. Likewise for values 1 and 2.
+
+ * There is only one `const_vector' expression with value 0 for each
+ vector mode, be it an integer or a double constant vector.
+
+ * No `label_ref' or `scratch' appears in more than one place in the
+ RTL structure; in other words, it is safe to do a tree-walk of all
+ the insns in the function and assume that each time a `label_ref'
+ or `scratch' is seen it is distinct from all others that are seen.
+
+ * Only one `mem' object is normally created for each static variable
+ or stack slot, so these objects are frequently shared in all the
+ places they appear. However, separate but equal objects for these
+ variables are occasionally made.
+
+ * When a single `asm' statement has multiple output operands, a
+ distinct `asm_operands' expression is made for each output operand.
+ However, these all share the vector which contains the sequence of
+ input operands. This sharing is used later on to test whether two
+ `asm_operands' expressions come from the same statement, so all
+ optimizations must carefully preserve the sharing if they copy the
+ vector at all.
+
+ * No RTL object appears in more than one place in the RTL structure
+ except as described above. Many passes of the compiler rely on
+ this by assuming that they can modify RTL objects in place without
+ unwanted side-effects on other insns.
+
+ * During initial RTL generation, shared structure is freely
+ introduced. After all the RTL for a function has been generated,
+ all shared structure is copied by `unshare_all_rtl' in
+ `emit-rtl.c', after which the above rules are guaranteed to be
+ followed.
+
+ * During the combiner pass, shared structure within an insn can exist
+ temporarily. However, the shared structure is copied before the
+ combiner is finished with the insn. This is done by calling
+ `copy_rtx_if_shared', which is a subroutine of `unshare_all_rtl'.
+
+\1f
+File: gccint.info, Node: Reading RTL, Prev: Sharing, Up: RTL
+
+8.20 Reading RTL
+================
+
+To read an RTL object from a file, call `read_rtx'. It takes one
+argument, a stdio stream, and returns a single RTL object. This routine
+is defined in `read-rtl.c'. It is not available in the compiler
+itself, only the various programs that generate the compiler back end
+from the machine description.
+
+ People frequently have the idea of using RTL stored as text in a
+file as an interface between a language front end and the bulk of GCC.
+This idea is not feasible.
+
+ GCC was designed to use RTL internally only. Correct RTL for a given
+program is very dependent on the particular target machine. And the RTL
+does not contain all the information about the program.
+
+ The proper way to interface GCC to a new language front end is with
+the "tree" data structure, described in the files `tree.h' and
+`tree.def'. The documentation for this structure (*note Trees::) is
+incomplete.
+
+\1f
+File: gccint.info, Node: Machine Desc, Next: Target Macros, Prev: RTL, Up: Top
+
+9 Machine Descriptions
+**********************
+
+A machine description has two parts: a file of instruction patterns
+(`.md' file) and a C header file of macro definitions.
+
+ The `.md' file for a target machine contains a pattern for each
+instruction that the target machine supports (or at least each
+instruction that is worth telling the compiler about). It may also
+contain comments. A semicolon causes the rest of the line to be a
+comment, unless the semicolon is inside a quoted string.
+
+ See the next chapter for information on the C header file.
+
+* Menu:
+
+* Overview:: How the machine description is used.
+* Patterns:: How to write instruction patterns.
+* Example:: An explained example of a `define_insn' pattern.
+* RTL Template:: The RTL template defines what insns match a pattern.
+* Output Template:: The output template says how to make assembler code
+ from such an insn.
+* Output Statement:: For more generality, write C code to output
+ the assembler code.
+* Constraints:: When not all operands are general operands.
+* Standard Names:: Names mark patterns to use for code generation.
+* Pattern Ordering:: When the order of patterns makes a difference.
+* Dependent Patterns:: Having one pattern may make you need another.
+* Jump Patterns:: Special considerations for patterns for jump insns.
+* Looping Patterns:: How to define patterns for special looping insns.
+* Insn Canonicalizations::Canonicalization of Instructions
+* Expander Definitions::Generating a sequence of several RTL insns
+ for a standard operation.
+* Insn Splitting:: Splitting Instructions into Multiple Instructions.
+* Including Patterns:: Including Patterns in Machine Descriptions.
+* Peephole Definitions::Defining machine-specific peephole optimizations.
+* Insn Attributes:: Specifying the value of attributes for generated insns.
+* Conditional Execution::Generating `define_insn' patterns for
+ predication.
+* Constant Definitions::Defining symbolic constants that can be used in the
+ md file.
+
+\1f
+File: gccint.info, Node: Overview, Next: Patterns, Up: Machine Desc
+
+9.1 Overview of How the Machine Description is Used
+===================================================
+
+There are three main conversions that happen in the compiler:
+
+ 1. The front end reads the source code and builds a parse tree.
+
+ 2. The parse tree is used to generate an RTL insn list based on named
+ instruction patterns.
+
+ 3. The insn list is matched against the RTL templates to produce
+ assembler code.
+
+
+ For the generate pass, only the names of the insns matter, from
+either a named `define_insn' or a `define_expand'. The compiler will
+choose the pattern with the right name and apply the operands according
+to the documentation later in this chapter, without regard for the RTL
+template or operand constraints. Note that the names the compiler looks
+for are hard-coded in the compiler--it will ignore unnamed patterns and
+patterns with names it doesn't know about, but if you don't provide a
+named pattern it needs, it will abort.
+
+ If a `define_insn' is used, the template given is inserted into the
+insn list. If a `define_expand' is used, one of three things happens,
+based on the condition logic. The condition logic may manually create
+new insns for the insn list, say via `emit_insn()', and invoke `DONE'.
+For certain named patterns, it may invoke `FAIL' to tell the compiler
+to use an alternate way of performing that task. If it invokes neither
+`DONE' nor `FAIL', the template given in the pattern is inserted, as if
+the `define_expand' were a `define_insn'.
+
+ Once the insn list is generated, various optimization passes convert,
+replace, and rearrange the insns in the insn list. This is where the
+`define_split' and `define_peephole' patterns get used, for example.
+
+ Finally, the insn list's RTL is matched up with the RTL templates in
+the `define_insn' patterns, and those patterns are used to emit the
+final assembly code. For this purpose, each named `define_insn' acts
+like it's unnamed, since the names are ignored.
+
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Standard Names, Next: Pattern Ordering, Prev: Constraints, Up: Machine Desc
-
-Standard Pattern Names For Generation
-=====================================
-
- Here is a table of the instruction names that are meaningful in the
-RTL generation pass of the compiler. Giving one of these names to an
-instruction pattern tells the RTL generation pass that it can use the
-pattern to accomplish a certain task.
-
-`movM'
- Here M stands for a two-letter machine mode name, in lower case.
- This instruction pattern moves data with that machine mode from
- operand 1 to operand 0. For example, `movsi' moves full-word data.
-
- If operand 0 is a `subreg' with mode M of a register whose own
- mode is wider than M, the effect of this instruction is to store
- the specified value in the part of the register that corresponds
- to mode M. Bits outside of M, but which are within the same
- target word as the `subreg' are undefined. Bits which are outside
- the target word are left unchanged.
-
- This class of patterns is special in several ways. First of all,
- each of these names up to and including full word size _must_ be
- defined, because there is no other way to copy a datum from one
- place to another. If there are patterns accepting operands in
- larger modes, `movM' must be defined for integer modes of those
- sizes.
-
- Second, these patterns are not used solely in the RTL generation
- pass. Even the reload pass can generate move insns to copy values
- from stack slots into temporary registers. When it does so, one
- of the operands is a hard register and the other is an operand
- that can need to be reloaded into a register.
-
- Therefore, when given such a pair of operands, the pattern must
- generate RTL which needs no reloading and needs no temporary
- registers--no registers other than the operands. For example, if
- you support the pattern with a `define_expand', then in such a
- case the `define_expand' mustn't call `force_reg' or any other such
- function which might generate new pseudo registers.
-
- This requirement exists even for subword modes on a RISC machine
- where fetching those modes from memory normally requires several
- insns and some temporary registers.
-
- During reload a memory reference with an invalid address may be
- passed as an operand. Such an address will be replaced with a
- valid address later in the reload pass. In this case, nothing may
- be done with the address except to use it as it stands. If it is
- copied, it will not be replaced with a valid address. No attempt
- should be made to make such an address into a valid address and no
- routine (such as `change_address') that will do so may be called.
- Note that `general_operand' will fail when applied to such an
- address.
-
- The global variable `reload_in_progress' (which must be explicitly
- declared if required) can be used to determine whether such special
- handling is required.
-
- The variety of operands that have reloads depends on the rest of
- the machine description, but typically on a RISC machine these can
- only be pseudo registers that did not get hard registers, while on
- other machines explicit memory references will get optional
- reloads.
-
- If a scratch register is required to move an object to or from
- memory, it can be allocated using `gen_reg_rtx' prior to life
- analysis.
-
- If there are cases which need scratch registers during or after
- reload, you must define `SECONDARY_INPUT_RELOAD_CLASS' and/or
- `SECONDARY_OUTPUT_RELOAD_CLASS' to detect them, and provide
- patterns `reload_inM' or `reload_outM' to handle them. *Note
- Register Classes::.
-
- The global variable `no_new_pseudos' can be used to determine if it
- is unsafe to create new pseudo registers. If this variable is
- nonzero, then it is unsafe to call `gen_reg_rtx' to allocate a new
- pseudo.
-
- The constraints on a `movM' must permit moving any hard register
- to any other hard register provided that `HARD_REGNO_MODE_OK'
- permits mode M in both registers and `REGISTER_MOVE_COST' applied
- to their classes returns a value of 2.
-
- It is obligatory to support floating point `movM' instructions
- into and out of any registers that can hold fixed point values,
- because unions and structures (which have modes `SImode' or
- `DImode') can be in those registers and they may have floating
- point members.
-
- There may also be a need to support fixed point `movM'
- instructions in and out of floating point registers.
- Unfortunately, I have forgotten why this was so, and I don't know
- whether it is still true. If `HARD_REGNO_MODE_OK' rejects fixed
- point values in floating point registers, then the constraints of
- the fixed point `movM' instructions must be designed to avoid ever
- trying to reload into a floating point register.
-
-`reload_inM'
-`reload_outM'
- Like `movM', but used when a scratch register is required to move
- between operand 0 and operand 1. Operand 2 describes the scratch
- register. See the discussion of the `SECONDARY_RELOAD_CLASS'
- macro in *note Register Classes::.
-
- There are special restrictions on the form of the `match_operand's
- used in these patterns. First, only the predicate for the reload
- operand is examined, i.e., `reload_in' examines operand 1, but not
- the predicates for operand 0 or 2. Second, there may be only one
- alternative in the constraints. Third, only a single register
- class letter may be used for the constraint; subsequent constraint
- letters are ignored. As a special exception, an empty constraint
- string matches the `ALL_REGS' register class. This may relieve
- ports of the burden of defining an `ALL_REGS' constraint letter
- just for these patterns.
-
-`movstrictM'
- Like `movM' except that if operand 0 is a `subreg' with mode M of
- a register whose natural mode is wider, the `movstrictM'
- instruction is guaranteed not to alter any of the register except
- the part which belongs to mode M.
-
-`load_multiple'
- Load several consecutive memory locations into consecutive
- registers. Operand 0 is the first of the consecutive registers,
- operand 1 is the first memory location, and operand 2 is a
- constant: the number of consecutive registers.
-
- Define this only if the target machine really has such an
- instruction; do not define this if the most efficient way of
- loading consecutive registers from memory is to do them one at a
- time.
-
- On some machines, there are restrictions as to which consecutive
- registers can be stored into memory, such as particular starting or
- ending register numbers or only a range of valid counts. For those
- machines, use a `define_expand' (*note Expander Definitions::) and
- make the pattern fail if the restrictions are not met.
-
- Write the generated insn as a `parallel' with elements being a
- `set' of one register from the appropriate memory location (you may
- also need `use' or `clobber' elements). Use a `match_parallel'
- (*note RTL Template::) to recognize the insn. See `a29k.md' and
- `rs6000.md' for examples of the use of this insn pattern.
-
-`store_multiple'
- Similar to `load_multiple', but store several consecutive registers
- into consecutive memory locations. Operand 0 is the first of the
- consecutive memory locations, operand 1 is the first register, and
- operand 2 is a constant: the number of consecutive registers.
-
-`pushM'
- Output an push instruction. Operand 0 is value to push. Used
- only when `PUSH_ROUNDING' is defined. For historical reason, this
- pattern may be missing and in such case an `mov' expander is used
- instead, with a `MEM' expression forming the push operation. The
- `mov' expander method is deprecated.
-
-`addM3'
- Add operand 2 and operand 1, storing the result in operand 0. All
- operands must have mode M. This can be used even on two-address
- machines, by means of constraints requiring operands 1 and 0 to be
- the same location.
-
-`subM3', `mulM3'
-`divM3', `udivM3', `modM3', `umodM3'
-`sminM3', `smaxM3', `uminM3', `umaxM3'
-`andM3', `iorM3', `xorM3'
- Similar, for other arithmetic operations.
-
-`minM3', `maxM3'
- Floating point min and max operations. If both operands are zeros,
- or if either operand is NaN, then it is unspecified which of the
- two operands is returned as the result.
-
-`mulhisi3'
- Multiply operands 1 and 2, which have mode `HImode', and store a
- `SImode' product in operand 0.
-
-`mulqihi3', `mulsidi3'
- Similar widening-multiplication instructions of other widths.
-
-`umulqihi3', `umulhisi3', `umulsidi3'
- Similar widening-multiplication instructions that do unsigned
- multiplication.
-
-`smulM3_highpart'
- Perform a signed multiplication of operands 1 and 2, which have
- mode M, and store the most significant half of the product in
- operand 0. The least significant half of the product is discarded.
-
-`umulM3_highpart'
- Similar, but the multiplication is unsigned.
-
-`divmodM4'
- Signed division that produces both a quotient and a remainder.
- Operand 1 is divided by operand 2 to produce a quotient stored in
- operand 0 and a remainder stored in operand 3.
-
- For machines with an instruction that produces both a quotient and
- a remainder, provide a pattern for `divmodM4' but do not provide
- patterns for `divM3' and `modM3'. This allows optimization in the
- relatively common case when both the quotient and remainder are
- computed.
-
- If an instruction that just produces a quotient or just a remainder
- exists and is more efficient than the instruction that produces
- both, write the output routine of `divmodM4' to call
- `find_reg_note' and look for a `REG_UNUSED' note on the quotient
- or remainder and generate the appropriate instruction.
-
-`udivmodM4'
- Similar, but does unsigned division.
-
-`ashlM3'
- Arithmetic-shift operand 1 left by a number of bits specified by
- operand 2, and store the result in operand 0. Here M is the mode
- of operand 0 and operand 1; operand 2's mode is specified by the
- instruction pattern, and the compiler will convert the operand to
- that mode before generating the instruction.
-
-`ashrM3', `lshrM3', `rotlM3', `rotrM3'
- Other shift and rotate instructions, analogous to the `ashlM3'
- instructions.
-
-`negM2'
- Negate operand 1 and store the result in operand 0.
-
-`absM2'
- Store the absolute value of operand 1 into operand 0.
-
-`sqrtM2'
- Store the square root of operand 1 into operand 0.
-
- The `sqrt' built-in function of C always uses the mode which
- corresponds to the C data type `double'.
-
-`ffsM2'
- Store into operand 0 one plus the index of the least significant
- 1-bit of operand 1. If operand 1 is zero, store zero. M is the
- mode of operand 0; operand 1's mode is specified by the instruction
- pattern, and the compiler will convert the operand to that mode
- before generating the instruction.
-
- The `ffs' built-in function of C always uses the mode which
- corresponds to the C data type `int'.
-
-`one_cmplM2'
- Store the bitwise-complement of operand 1 into operand 0.
-
-`cmpM'
- Compare operand 0 and operand 1, and set the condition codes. The
- RTL pattern should look like this:
-
- (set (cc0) (compare (match_operand:M 0 ...)
- (match_operand:M 1 ...)))
-
-`tstM'
- Compare operand 0 against zero, and set the condition codes. The
- RTL pattern should look like this:
-
- (set (cc0) (match_operand:M 0 ...))
-
- `tstM' patterns should not be defined for machines that do not use
- `(cc0)'. Doing so would confuse the optimizer since it would no
- longer be clear which `set' operations were comparisons. The
- `cmpM' patterns should be used instead.
-
-`movstrM'
- Block move instruction. The addresses of the destination and
- source strings are the first two operands, and both are in mode
- `Pmode'.
-
- The number of bytes to move is the third operand, in mode M.
- Usually, you specify `word_mode' for M. However, if you can
- generate better code knowing the range of valid lengths is smaller
- than those representable in a full word, you should provide a
- pattern with a mode corresponding to the range of values you can
- handle efficiently (e.g., `QImode' for values in the range 0-127;
- note we avoid numbers that appear negative) and also a pattern
- with `word_mode'.
-
- The fourth operand is the known shared alignment of the source and
- destination, in the form of a `const_int' rtx. Thus, if the
- compiler knows that both source and destination are word-aligned,
- it may provide the value 4 for this operand.
-
- Descriptions of multiple `movstrM' patterns can only be beneficial
- if the patterns for smaller modes have fewer restrictions on their
- first, second and fourth operands. Note that the mode M in
- `movstrM' does not impose any restriction on the mode of
- individually moved data units in the block.
-
- These patterns need not give special consideration to the
- possibility that the source and destination strings might overlap.
-
-`clrstrM'
- Block clear instruction. The addresses of the destination string
- is the first operand, in mode `Pmode'. The number of bytes to
- clear is the second operand, in mode M. See `movstrM' for a
- discussion of the choice of mode.
-
- The third operand is the known alignment of the destination, in
- the form of a `const_int' rtx. Thus, if the compiler knows that
- the destination is word-aligned, it may provide the value 4 for
- this operand.
-
- The use for multiple `clrstrM' is as for `movstrM'.
-
-`cmpstrM'
- Block compare instruction, with five operands. Operand 0 is the
- output; it has mode M. The remaining four operands are like the
- operands of `movstrM'. The two memory blocks specified are
- compared byte by byte in lexicographic order. The effect of the
- instruction is to store a value in operand 0 whose sign indicates
- the result of the comparison.
-
-`strlenM'
- Compute the length of a string, with three operands. Operand 0 is
- the result (of mode M), operand 1 is a `mem' referring to the
- first character of the string, operand 2 is the character to
- search for (normally zero), and operand 3 is a constant describing
- the known alignment of the beginning of the string.
-
-`floatMN2'
- Convert signed integer operand 1 (valid for fixed point mode M) to
- floating point mode N and store in operand 0 (which has mode N).
-
-`floatunsMN2'
- Convert unsigned integer operand 1 (valid for fixed point mode M)
- to floating point mode N and store in operand 0 (which has mode N).
-
-`fixMN2'
- Convert operand 1 (valid for floating point mode M) to fixed point
- mode N as a signed number and store in operand 0 (which has mode
- N). This instruction's result is defined only when the value of
- operand 1 is an integer.
-
-`fixunsMN2'
- Convert operand 1 (valid for floating point mode M) to fixed point
- mode N as an unsigned number and store in operand 0 (which has
- mode N). This instruction's result is defined only when the value
- of operand 1 is an integer.
-
-`ftruncM2'
- Convert operand 1 (valid for floating point mode M) to an integer
- value, still represented in floating point mode M, and store it in
- operand 0 (valid for floating point mode M).
-
-`fix_truncMN2'
- Like `fixMN2' but works for any floating point value of mode M by
- converting the value to an integer.
-
-`fixuns_truncMN2'
- Like `fixunsMN2' but works for any floating point value of mode M
- by converting the value to an integer.
-
-`truncMN2'
- Truncate operand 1 (valid for mode M) to mode N and store in
- operand 0 (which has mode N). Both modes must be fixed point or
- both floating point.
-
-`extendMN2'
- Sign-extend operand 1 (valid for mode M) to mode N and store in
- operand 0 (which has mode N). Both modes must be fixed point or
- both floating point.
-
-`zero_extendMN2'
- Zero-extend operand 1 (valid for mode M) to mode N and store in
- operand 0 (which has mode N). Both modes must be fixed point.
-
-`extv'
- Extract a bit-field from operand 1 (a register or memory operand),
- where operand 2 specifies the width in bits and operand 3 the
- starting bit, and store it in operand 0. Operand 0 must have mode
- `word_mode'. Operand 1 may have mode `byte_mode' or `word_mode';
- often `word_mode' is allowed only for registers. Operands 2 and 3
- must be valid for `word_mode'.
-
- The RTL generation pass generates this instruction only with
- constants for operands 2 and 3.
-
- The bit-field value is sign-extended to a full word integer before
- it is stored in operand 0.
-
-`extzv'
- Like `extv' except that the bit-field value is zero-extended.
-
-`insv'
- Store operand 3 (which must be valid for `word_mode') into a
- bit-field in operand 0, where operand 1 specifies the width in
- bits and operand 2 the starting bit. Operand 0 may have mode
- `byte_mode' or `word_mode'; often `word_mode' is allowed only for
- registers. Operands 1 and 2 must be valid for `word_mode'.
-
- The RTL generation pass generates this instruction only with
- constants for operands 1 and 2.
-
-`movMODEcc'
- Conditionally move operand 2 or operand 3 into operand 0 according
- to the comparison in operand 1. If the comparison is true,
- operand 2 is moved into operand 0, otherwise operand 3 is moved.
-
- The mode of the operands being compared need not be the same as
- the operands being moved. Some machines, sparc64 for example,
- have instructions that conditionally move an integer value based
- on the floating point condition codes and vice versa.
-
- If the machine does not have conditional move instructions, do not
- define these patterns.
-
-`sCOND'
- Store zero or nonzero in the operand according to the condition
- codes. Value stored is nonzero iff the condition COND is true.
- COND is the name of a comparison operation expression code, such
- as `eq', `lt' or `leu'.
-
- You specify the mode that the operand must have when you write the
- `match_operand' expression. The compiler automatically sees which
- mode you have used and supplies an operand of that mode.
-
- The value stored for a true condition must have 1 as its low bit,
- or else must be negative. Otherwise the instruction is not
- suitable and you should omit it from the machine description. You
- describe to the compiler exactly which value is stored by defining
- the macro `STORE_FLAG_VALUE' (*note Misc::). If a description
- cannot be found that can be used for all the `sCOND' patterns, you
- should omit those operations from the machine description.
-
- These operations may fail, but should do so only in relatively
- uncommon cases; if they would fail for common cases involving
- integer comparisons, it is best to omit these patterns.
-
- If these operations are omitted, the compiler will usually
- generate code that copies the constant one to the target and
- branches around an assignment of zero to the target. If this code
- is more efficient than the potential instructions used for the
- `sCOND' pattern followed by those required to convert the result
- into a 1 or a zero in `SImode', you should omit the `sCOND'
- operations from the machine description.
-
-`bCOND'
- Conditional branch instruction. Operand 0 is a `label_ref' that
- refers to the label to jump to. Jump if the condition codes meet
- condition COND.
-
- Some machines do not follow the model assumed here where a
- comparison instruction is followed by a conditional branch
- instruction. In that case, the `cmpM' (and `tstM') patterns should
- simply store the operands away and generate all the required insns
- in a `define_expand' (*note Expander Definitions::) for the
- conditional branch operations. All calls to expand `bCOND'
- patterns are immediately preceded by calls to expand either a
- `cmpM' pattern or a `tstM' pattern.
-
- Machines that use a pseudo register for the condition code value,
- or where the mode used for the comparison depends on the condition
- being tested, should also use the above mechanism. *Note Jump
- Patterns::.
-
- The above discussion also applies to the `movMODEcc' and `sCOND'
- patterns.
-
-`jump'
- A jump inside a function; an unconditional branch. Operand 0 is
- the `label_ref' of the label to jump to. This pattern name is
- mandatory on all machines.
-
-`call'
- Subroutine call instruction returning no value. Operand 0 is the
- function to call; operand 1 is the number of bytes of arguments
- pushed as a `const_int'; operand 2 is the number of registers used
- as operands.
-
- On most machines, operand 2 is not actually stored into the RTL
- pattern. It is supplied for the sake of some RISC machines which
- need to put this information into the assembler code; they can put
- it in the RTL instead of operand 1.
-
- Operand 0 should be a `mem' RTX whose address is the address of the
- function. Note, however, that this address can be a `symbol_ref'
- expression even if it would not be a legitimate memory address on
- the target machine. If it is also not a valid argument for a call
- instruction, the pattern for this operation should be a
- `define_expand' (*note Expander Definitions::) that places the
- address into a register and uses that register in the call
- instruction.
-
-`call_value'
- Subroutine call instruction returning a value. Operand 0 is the
- hard register in which the value is returned. There are three more
- operands, the same as the three operands of the `call' instruction
- (but with numbers increased by one).
-
- Subroutines that return `BLKmode' objects use the `call' insn.
-
-`call_pop', `call_value_pop'
- Similar to `call' and `call_value', except used if defined and if
- `RETURN_POPS_ARGS' is nonzero. They should emit a `parallel' that
- contains both the function call and a `set' to indicate the
- adjustment made to the frame pointer.
-
- For machines where `RETURN_POPS_ARGS' can be nonzero, the use of
- these patterns increases the number of functions for which the
- frame pointer can be eliminated, if desired.
-
-`untyped_call'
- Subroutine call instruction returning a value of any type.
- Operand 0 is the function to call; operand 1 is a memory location
- where the result of calling the function is to be stored; operand
- 2 is a `parallel' expression where each element is a `set'
- expression that indicates the saving of a function return value
- into the result block.
-
- This instruction pattern should be defined to support
- `__builtin_apply' on machines where special instructions are needed
- to call a subroutine with arbitrary arguments or to save the value
- returned. This instruction pattern is required on machines that
- have multiple registers that can hold a return value (i.e.
- `FUNCTION_VALUE_REGNO_P' is true for more than one register).
-
-`return'
- Subroutine return instruction. This instruction pattern name
- should be defined only if a single instruction can do all the work
- of returning from a function.
-
- Like the `movM' patterns, this pattern is also used after the RTL
- generation phase. In this case it is to support machines where
- multiple instructions are usually needed to return from a
- function, but some class of functions only requires one
- instruction to implement a return. Normally, the applicable
- functions are those which do not need to save any registers or
- allocate stack space.
-
- For such machines, the condition specified in this pattern should
- only be true when `reload_completed' is nonzero and the function's
- epilogue would only be a single instruction. For machines with
- register windows, the routine `leaf_function_p' may be used to
- determine if a register window push is required.
-
- Machines that have conditional return instructions should define
- patterns such as
-
- (define_insn ""
- [(set (pc)
- (if_then_else (match_operator
- 0 "comparison_operator"
- [(cc0) (const_int 0)])
- (return)
- (pc)))]
- "CONDITION"
- "...")
-
- where CONDITION would normally be the same condition specified on
- the named `return' pattern.
-
-`untyped_return'
- Untyped subroutine return instruction. This instruction pattern
- should be defined to support `__builtin_return' on machines where
- special instructions are needed to return a value of any type.
-
- Operand 0 is a memory location where the result of calling a
- function with `__builtin_apply' is stored; operand 1 is a
- `parallel' expression where each element is a `set' expression
- that indicates the restoring of a function return value from the
- result block.
-
-`nop'
- No-op instruction. This instruction pattern name should always be
- defined to output a no-op in assembler code. `(const_int 0)' will
- do as an RTL pattern.
-
-`indirect_jump'
- An instruction to jump to an address which is operand zero. This
- pattern name is mandatory on all machines.
-
-`casesi'
- Instruction to jump through a dispatch table, including bounds
- checking. This instruction takes five operands:
-
- 1. The index to dispatch on, which has mode `SImode'.
-
- 2. The lower bound for indices in the table, an integer constant.
-
- 3. The total range of indices in the table--the largest index
- minus the smallest one (both inclusive).
-
- 4. A label that precedes the table itself.
-
- 5. A label to jump to if the index has a value outside the
- bounds. (If the machine-description macro
- `CASE_DROPS_THROUGH' is defined, then an out-of-bounds index
- drops through to the code following the jump table instead of
- jumping to this label. In that case, this label is not
- actually used by the `casesi' instruction, but it is always
- provided as an operand.)
-
- The table is a `addr_vec' or `addr_diff_vec' inside of a
- `jump_insn'. The number of elements in the table is one plus the
- difference between the upper bound and the lower bound.
-
-`tablejump'
- Instruction to jump to a variable address. This is a low-level
- capability which can be used to implement a dispatch table when
- there is no `casesi' pattern.
-
- This pattern requires two operands: the address or offset, and a
- label which should immediately precede the jump table. If the
- macro `CASE_VECTOR_PC_RELATIVE' evaluates to a nonzero value then
- the first operand is an offset which counts from the address of
- the table; otherwise, it is an absolute address to jump to. In
- either case, the first operand has mode `Pmode'.
-
- The `tablejump' insn is always the last insn before the jump table
- it uses. Its assembler code normally has no need to use the
- second operand, but you should incorporate it in the RTL pattern so
- that the jump optimizer will not delete the table as unreachable
- code.
-
-`decrement_and_branch_until_zero'
- Conditional branch instruction that decrements a register and
- jumps if the register is nonzero. Operand 0 is the register to
- decrement and test; operand 1 is the label to jump to if the
- register is nonzero. *Note Looping Patterns::.
-
- This optional instruction pattern is only used by the combiner,
- typically for loops reversed by the loop optimizer when strength
- reduction is enabled.
-
-`doloop_end'
- Conditional branch instruction that decrements a register and
- jumps if the register is nonzero. This instruction takes five
- operands: Operand 0 is the register to decrement and test; operand
- 1 is the number of loop iterations as a `const_int' or
- `const0_rtx' if this cannot be determined until run-time; operand
- 2 is the actual or estimated maximum number of iterations as a
- `const_int'; operand 3 is the number of enclosed loops as a
- `const_int' (an innermost loop has a value of 1); operand 4 is the
- label to jump to if the register is nonzero. *Note Looping
- Patterns::.
-
- This optional instruction pattern should be defined for machines
- with low-overhead looping instructions as the loop optimizer will
- try to modify suitable loops to utilize it. If nested
- low-overhead looping is not supported, use a `define_expand'
- (*note Expander Definitions::) and make the pattern fail if
- operand 3 is not `const1_rtx'. Similarly, if the actual or
- estimated maximum number of iterations is too large for this
- instruction, make it fail.
-
-`doloop_begin'
- Companion instruction to `doloop_end' required for machines that
- need to perform some initialization, such as loading special
- registers used by a low-overhead looping instruction. If
- initialization insns do not always need to be emitted, use a
- `define_expand' (*note Expander Definitions::) and make it fail.
-
-`canonicalize_funcptr_for_compare'
- Canonicalize the function pointer in operand 1 and store the result
- into operand 0.
-
- Operand 0 is always a `reg' and has mode `Pmode'; operand 1 may be
- a `reg', `mem', `symbol_ref', `const_int', etc and also has mode
- `Pmode'.
-
- Canonicalization of a function pointer usually involves computing
- the address of the function which would be called if the function
- pointer were used in an indirect call.
-
- Only define this pattern if function pointers on the target machine
- can have different values but still call the same function when
- used in an indirect call.
-
-`save_stack_block'
-`save_stack_function'
-`save_stack_nonlocal'
-`restore_stack_block'
-`restore_stack_function'
-`restore_stack_nonlocal'
- Most machines save and restore the stack pointer by copying it to
- or from an object of mode `Pmode'. Do not define these patterns on
- such machines.
-
- Some machines require special handling for stack pointer saves and
- restores. On those machines, define the patterns corresponding to
- the non-standard cases by using a `define_expand' (*note Expander
- Definitions::) that produces the required insns. The three types
- of saves and restores are:
-
- 1. `save_stack_block' saves the stack pointer at the start of a
- block that allocates a variable-sized object, and
- `restore_stack_block' restores the stack pointer when the
- block is exited.
-
- 2. `save_stack_function' and `restore_stack_function' do a
- similar job for the outermost block of a function and are
- used when the function allocates variable-sized objects or
- calls `alloca'. Only the epilogue uses the restored stack
- pointer, allowing a simpler save or restore sequence on some
- machines.
-
- 3. `save_stack_nonlocal' is used in functions that contain labels
- branched to by nested functions. It saves the stack pointer
- in such a way that the inner function can use
- `restore_stack_nonlocal' to restore the stack pointer. The
- compiler generates code to restore the frame and argument
- pointer registers, but some machines require saving and
- restoring additional data such as register window information
- or stack backchains. Place insns in these patterns to save
- and restore any such required data.
-
- When saving the stack pointer, operand 0 is the save area and
- operand 1 is the stack pointer. The mode used to allocate the
- save area defaults to `Pmode' but you can override that choice by
- defining the `STACK_SAVEAREA_MODE' macro (*note Storage Layout::).
- You must specify an integral mode, or `VOIDmode' if no save area
- is needed for a particular type of save (either because no save is
- needed or because a machine-specific save area can be used).
- Operand 0 is the stack pointer and operand 1 is the save area for
- restore operations. If `save_stack_block' is defined, operand 0
- must not be `VOIDmode' since these saves can be arbitrarily nested.
-
- A save area is a `mem' that is at a constant offset from
- `virtual_stack_vars_rtx' when the stack pointer is saved for use by
- nonlocal gotos and a `reg' in the other two cases.
-
-`allocate_stack'
- Subtract (or add if `STACK_GROWS_DOWNWARD' is undefined) operand 1
- from the stack pointer to create space for dynamically allocated
- data.
-
- Store the resultant pointer to this space into operand 0. If you
- are allocating space from the main stack, do this by emitting a
- move insn to copy `virtual_stack_dynamic_rtx' to operand 0. If
- you are allocating the space elsewhere, generate code to copy the
- location of the space to operand 0. In the latter case, you must
- ensure this space gets freed when the corresponding space on the
- main stack is free.
-
- Do not define this pattern if all that must be done is the
- subtraction. Some machines require other operations such as stack
- probes or maintaining the back chain. Define this pattern to emit
- those operations in addition to updating the stack pointer.
-
-`probe'
- Some machines require instructions to be executed after space is
- allocated from the stack, for example to generate a reference at
- the bottom of the stack.
-
- If you need to emit instructions before the stack has been
- adjusted, put them into the `allocate_stack' pattern. Otherwise,
- define this pattern to emit the required instructions.
-
- No operands are provided.
-
-`check_stack'
- If stack checking cannot be done on your system by probing the
- stack with a load or store instruction (*note Stack Checking::),
- define this pattern to perform the needed check and signaling an
- error if the stack has overflowed. The single operand is the
- location in the stack furthest from the current stack pointer that
- you need to validate. Normally, on machines where this pattern is
- needed, you would obtain the stack limit from a global or
- thread-specific variable or register.
-
-`nonlocal_goto'
- Emit code to generate a non-local goto, e.g., a jump from one
- function to a label in an outer function. This pattern has four
- arguments, each representing a value to be used in the jump. The
- first argument is to be loaded into the frame pointer, the second
- is the address to branch to (code to dispatch to the actual label),
- the third is the address of a location where the stack is saved,
- and the last is the address of the label, to be placed in the
- location for the incoming static chain.
-
- On most machines you need not define this pattern, since GCC will
- already generate the correct code, which is to load the frame
- pointer and static chain, restore the stack (using the
- `restore_stack_nonlocal' pattern, if defined), and jump indirectly
- to the dispatcher. You need only define this pattern if this code
- will not work on your machine.
-
-`nonlocal_goto_receiver'
- This pattern, if defined, contains code needed at the target of a
- nonlocal goto after the code already generated by GCC. You will
- not normally need to define this pattern. A typical reason why
- you might need this pattern is if some value, such as a pointer to
- a global table, must be restored when the frame pointer is
- restored. Note that a nonlocal goto only occurs within a
- unit-of-translation, so a global table pointer that is shared by
- all functions of a given module need not be restored. There are
- no arguments.
-
-`exception_receiver'
- This pattern, if defined, contains code needed at the site of an
- exception handler that isn't needed at the site of a nonlocal
- goto. You will not normally need to define this pattern. A
- typical reason why you might need this pattern is if some value,
- such as a pointer to a global table, must be restored after
- control flow is branched to the handler of an exception. There
- are no arguments.
-
-`builtin_setjmp_setup'
- This pattern, if defined, contains additional code needed to
- initialize the `jmp_buf'. You will not normally need to define
- this pattern. A typical reason why you might need this pattern is
- if some value, such as a pointer to a global table, must be
- restored. Though it is preferred that the pointer value be
- recalculated if possible (given the address of a label for
- instance). The single argument is a pointer to the `jmp_buf'.
- Note that the buffer is five words long and that the first three
- are normally used by the generic mechanism.
-
-`builtin_setjmp_receiver'
- This pattern, if defined, contains code needed at the site of an
- built-in setjmp that isn't needed at the site of a nonlocal goto.
- You will not normally need to define this pattern. A typical
- reason why you might need this pattern is if some value, such as a
- pointer to a global table, must be restored. It takes one
- argument, which is the label to which builtin_longjmp transfered
- control; this pattern may be emitted at a small offset from that
- label.
-
-`builtin_longjmp'
- This pattern, if defined, performs the entire action of the
- longjmp. You will not normally need to define this pattern unless
- you also define `builtin_setjmp_setup'. The single argument is a
- pointer to the `jmp_buf'.
-
-`eh_return'
- This pattern, if defined, affects the way `__builtin_eh_return',
- and thence the call frame exception handling library routines, are
- built. It is intended to handle non-trivial actions needed along
- the abnormal return path.
-
- The pattern takes two arguments. The first is an offset to be
- applied to the stack pointer. It will have been copied to some
- appropriate location (typically `EH_RETURN_STACKADJ_RTX') which
- will survive until after reload to when the normal epilogue is
- generated. The second argument is the address of the exception
- handler to which the function should return. This will normally
- need to copied by the pattern to some special register or memory
- location.
-
- This pattern only needs to be defined if call frame exception
- handling is to be used, and simple moves involving
- `EH_RETURN_STACKADJ_RTX' and `EH_RETURN_HANDLER_RTX' are not
- sufficient.
-
-`prologue'
- This pattern, if defined, emits RTL for entry to a function. The
- function entry is responsible for setting up the stack frame,
- initializing the frame pointer register, saving callee saved
- registers, etc.
-
- Using a prologue pattern is generally preferred over defining
- `TARGET_ASM_FUNCTION_PROLOGUE' to emit assembly code for the
- prologue.
-
- The `prologue' pattern is particularly useful for targets which
- perform instruction scheduling.
-
-`epilogue'
- This pattern emits RTL for exit from a function. The function
- exit is responsible for deallocating the stack frame, restoring
- callee saved registers and emitting the return instruction.
-
- Using an epilogue pattern is generally preferred over defining
- `TARGET_ASM_FUNCTION_EPILOGUE' to emit assembly code for the
- epilogue.
-
- The `epilogue' pattern is particularly useful for targets which
- perform instruction scheduling or which have delay slots for their
- return instruction.
-
-`sibcall_epilogue'
- This pattern, if defined, emits RTL for exit from a function
- without the final branch back to the calling function. This
- pattern will be emitted before any sibling call (aka tail call)
- sites.
-
- The `sibcall_epilogue' pattern must not clobber any arguments used
- for parameter passing or any stack slots for arguments passed to
- the current function.
-
-`trap'
- This pattern, if defined, signals an error, typically by causing
- some kind of signal to be raised. Among other places, it is used
- by the Java front end to signal `invalid array index' exceptions.
-
-`conditional_trap'
- Conditional trap instruction. Operand 0 is a piece of RTL which
- performs a comparison. Operand 1 is the trap code, an integer.
-
- A typical `conditional_trap' pattern looks like
-
- (define_insn "conditional_trap"
- [(trap_if (match_operator 0 "trap_operator"
- [(cc0) (const_int 0)])
- (match_operand 1 "const_int_operand" "i"))]
- ""
- "...")
-
-`prefetch'
- This pattern, if defined, emits code for a non-faulting data
- prefetch instruction. Operand 0 is the address of the memory to
- prefetch. Operand 1 is a constant 1 if the prefetch is preparing
- for a write to the memory address, or a constant 0 otherwise.
- Operand 2 is the expected degree of temporal locality of the data
- and is a value between 0 and 3, inclusive; 0 means that the data
- has no temporal locality, so it need not be left in the cache
- after the access; 3 means that the data has a high degree of
- temporal locality and should be left in all levels of cache
- possible; 1 and 2 mean, respectively, a low or moderate degree of
- temporal locality.
-
- Targets that do not support write prefetches or locality hints can
- ignore the values of operands 1 and 2.
-
-`cycle_display'
- This pattern, if present, will be emitted by the instruction
- scheduler at the beginning of each new clock cycle. This can be
- used for annotating the assembler output with cycle counts.
- Operand 0 is a `const_int' that holds the clock cycle.
-
-
-\1f
-File: gccint.info, Node: Pattern Ordering, Next: Dependent Patterns, Prev: Standard Names, Up: Machine Desc
-
-When the Order of Patterns Matters
-==================================
-
- Sometimes an insn can match more than one instruction pattern. Then
-the pattern that appears first in the machine description is the one
-used. Therefore, more specific patterns (patterns that will match
-fewer things) and faster instructions (those that will produce better
-code when they do match) should usually go first in the description.
-
- In some cases the effect of ordering the patterns can be used to hide
-a pattern when it is not valid. For example, the 68000 has an
-instruction for converting a fullword to floating point and another for
-converting a byte to floating point. An instruction converting an
-integer to floating point could match either one. We put the pattern
-to convert the fullword first to make sure that one will be used rather
-than the other. (Otherwise a large integer might be generated as a
-single-byte immediate quantity, which would not work.) Instead of
-using this pattern ordering it would be possible to make the pattern
-for convert-a-byte smart enough to deal properly with any constant
-value.
-
-\1f
-File: gccint.info, Node: Dependent Patterns, Next: Jump Patterns, Prev: Pattern Ordering, Up: Machine Desc
-
-Interdependence of Patterns
-===========================
-
- Every machine description must have a named pattern for each of the
-conditional branch names `bCOND'. The recognition template must always
-have the form
-
- (set (pc)
- (if_then_else (COND (cc0) (const_int 0))
- (label_ref (match_operand 0 "" ""))
- (pc)))
-
-In addition, every machine description must have an anonymous pattern
-for each of the possible reverse-conditional branches. Their templates
-look like
-
- (set (pc)
- (if_then_else (COND (cc0) (const_int 0))
- (pc)
- (label_ref (match_operand 0 "" ""))))
-
-They are necessary because jump optimization can turn direct-conditional
-branches into reverse-conditional branches.
-
- It is often convenient to use the `match_operator' construct to
-reduce the number of patterns that must be specified for branches. For
-example,
-
- (define_insn ""
- [(set (pc)
- (if_then_else (match_operator 0 "comparison_operator"
- [(cc0) (const_int 0)])
- (pc)
- (label_ref (match_operand 1 "" ""))))]
- "CONDITION"
- "...")
-
- In some cases machines support instructions identical except for the
-machine mode of one or more operands. For example, there may be
-"sign-extend halfword" and "sign-extend byte" instructions whose
-patterns are
-
- (set (match_operand:SI 0 ...)
- (extend:SI (match_operand:HI 1 ...)))
-
- (set (match_operand:SI 0 ...)
- (extend:SI (match_operand:QI 1 ...)))
-
-Constant integers do not specify a machine mode, so an instruction to
-extend a constant value could match either pattern. The pattern it
-actually will match is the one that appears first in the file. For
-correct results, this must be the one for the widest possible mode
-(`HImode', here). If the pattern matches the `QImode' instruction, the
-results will be incorrect if the constant value does not actually fit
-that mode.
-
- Such instructions to extend constants are rarely generated because
-they are optimized away, but they do occasionally happen in nonoptimized
-compilations.
-
- If a constraint in a pattern allows a constant, the reload pass may
-replace a register with a constant permitted by the constraint in some
-cases. Similarly for memory references. Because of this substitution,
-you should not provide separate patterns for increment and decrement
-instructions. Instead, they should be generated from the same pattern
-that supports register-register add insns by examining the operands and
-generating the appropriate machine instruction.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Jump Patterns, Next: Looping Patterns, Prev: Dependent Patterns, Up: Machine Desc
-
-Defining Jump Instruction Patterns
-==================================
-
- For most machines, GCC assumes that the machine has a condition code.
-A comparison insn sets the condition code, recording the results of both
-signed and unsigned comparison of the given operands. A separate branch
-insn tests the condition code and branches or not according its value.
-The branch insns come in distinct signed and unsigned flavors. Many
-common machines, such as the VAX, the 68000 and the 32000, work this
-way.
-
- Some machines have distinct signed and unsigned compare
-instructions, and only one set of conditional branch instructions. The
-easiest way to handle these machines is to treat them just like the
-others until the final stage where assembly code is written. At this
-time, when outputting code for the compare instruction, peek ahead at
-the following branch using `next_cc0_user (insn)'. (The variable
-`insn' refers to the insn being output, in the output-writing code in
-an instruction pattern.) If the RTL says that is an unsigned branch,
-output an unsigned compare; otherwise output a signed compare. When
-the branch itself is output, you can treat signed and unsigned branches
-identically.
-
- The reason you can do this is that GCC always generates a pair of
-consecutive RTL insns, possibly separated by `note' insns, one to set
-the condition code and one to test it, and keeps the pair inviolate
-until the end.
-
- To go with this technique, you must define the machine-description
-macro `NOTICE_UPDATE_CC' to do `CC_STATUS_INIT'; in other words, no
-compare instruction is superfluous.
-
- Some machines have compare-and-branch instructions and no condition
-code. A similar technique works for them. When it is time to "output"
-a compare instruction, record its operands in two static variables.
-When outputting the branch-on-condition-code instruction that follows,
-actually output a compare-and-branch instruction that uses the
-remembered operands.
-
- It also works to define patterns for compare-and-branch instructions.
-In optimizing compilation, the pair of compare and branch instructions
-will be combined according to these patterns. But this does not happen
-if optimization is not requested. So you must use one of the solutions
-above in addition to any special patterns you define.
-
- In many RISC machines, most instructions do not affect the condition
-code and there may not even be a separate condition code register. On
-these machines, the restriction that the definition and use of the
-condition code be adjacent insns is not necessary and can prevent
-important optimizations. For example, on the IBM RS/6000, there is a
-delay for taken branches unless the condition code register is set three
-instructions earlier than the conditional branch. The instruction
-scheduler cannot perform this optimization if it is not permitted to
-separate the definition and use of the condition code register.
-
- On these machines, do not use `(cc0)', but instead use a register to
-represent the condition code. If there is a specific condition code
-register in the machine, use a hard register. If the condition code or
-comparison result can be placed in any general register, or if there are
-multiple condition registers, use a pseudo register.
-
- On some machines, the type of branch instruction generated may
-depend on the way the condition code was produced; for example, on the
-68k and Sparc, setting the condition code directly from an add or
-subtract instruction does not clear the overflow bit the way that a test
-instruction does, so a different branch instruction must be used for
-some conditional branches. For machines that use `(cc0)', the set and
-use of the condition code must be adjacent (separated only by `note'
-insns) allowing flags in `cc_status' to be used. (*Note Condition
-Code::.) Also, the comparison and branch insns can be located from
-each other by using the functions `prev_cc0_setter' and `next_cc0_user'.
-
- However, this is not true on machines that do not use `(cc0)'. On
-those machines, no assumptions can be made about the adjacency of the
-compare and branch insns and the above methods cannot be used. Instead,
-we use the machine mode of the condition code register to record
-different formats of the condition code register.
-
- Registers used to store the condition code value should have a mode
-that is in class `MODE_CC'. Normally, it will be `CCmode'. If
-additional modes are required (as for the add example mentioned above in
-the Sparc), define the macro `EXTRA_CC_MODES' to list the additional
-modes required (*note Condition Code::). Also define `SELECT_CC_MODE'
-to choose a mode given an operand of a compare.
-
- If it is known during RTL generation that a different mode will be
-required (for example, if the machine has separate compare instructions
-for signed and unsigned quantities, like most IBM processors), they can
-be specified at that time.
-
- If the cases that require different modes would be made by
-instruction combination, the macro `SELECT_CC_MODE' determines which
-machine mode should be used for the comparison result. The patterns
-should be written using that mode. To support the case of the add on
-the Sparc discussed above, we have the pattern
-
- (define_insn ""
- [(set (reg:CC_NOOV 0)
- (compare:CC_NOOV
- (plus:SI (match_operand:SI 0 "register_operand" "%r")
- (match_operand:SI 1 "arith_operand" "rI"))
- (const_int 0)))]
- ""
- "...")
-
- The `SELECT_CC_MODE' macro on the Sparc returns `CC_NOOVmode' for
-comparisons whose argument is a `plus'.
-
-\1f
-File: gccint.info, Node: Looping Patterns, Next: Insn Canonicalizations, Prev: Jump Patterns, Up: Machine Desc
-
-Defining Looping Instruction Patterns
-=====================================
-
- Some machines have special jump instructions that can be utilised to
-make loops more efficient. A common example is the 68000 `dbra'
-instruction which performs a decrement of a register and a branch if the
-result was greater than zero. Other machines, in particular digital
-signal processors (DSPs), have special block repeat instructions to
-provide low-overhead loop support. For example, the TI TMS320C3x/C4x
-DSPs have a block repeat instruction that loads special registers to
-mark the top and end of a loop and to count the number of loop
-iterations. This avoids the need for fetching and executing a
-`dbra'-like instruction and avoids pipeline stalls associated with the
-jump.
-
- GCC has three special named patterns to support low overhead looping.
-They are `decrement_and_branch_until_zero', `doloop_begin', and
-`doloop_end'. The first pattern, `decrement_and_branch_until_zero', is
-not emitted during RTL generation but may be emitted during the
-instruction combination phase. This requires the assistance of the
-loop optimizer, using information collected during strength reduction,
-to reverse a loop to count down to zero. Some targets also require the
-loop optimizer to add a `REG_NONNEG' note to indicate that the
-iteration count is always positive. This is needed if the target
-performs a signed loop termination test. For example, the 68000 uses a
-pattern similar to the following for its `dbra' instruction:
-
- (define_insn "decrement_and_branch_until_zero"
- [(set (pc)
- (if_then_else
- (ge (plus:SI (match_operand:SI 0 "general_operand" "+d*am")
- (const_int -1))
- (const_int 0))
- (label_ref (match_operand 1 "" ""))
- (pc)))
- (set (match_dup 0)
- (plus:SI (match_dup 0)
- (const_int -1)))]
- "find_reg_note (insn, REG_NONNEG, 0)"
- "...")
-
- Note that since the insn is both a jump insn and has an output, it
-must deal with its own reloads, hence the `m' constraints. Also note
-that since this insn is generated by the instruction combination phase
-combining two sequential insns together into an implicit parallel insn,
-the iteration counter needs to be biased by the same amount as the
-decrement operation, in this case -1. Note that the following similar
-pattern will not be matched by the combiner.
-
- (define_insn "decrement_and_branch_until_zero"
- [(set (pc)
- (if_then_else
- (ge (match_operand:SI 0 "general_operand" "+d*am")
- (const_int 1))
- (label_ref (match_operand 1 "" ""))
- (pc)))
- (set (match_dup 0)
- (plus:SI (match_dup 0)
- (const_int -1)))]
- "find_reg_note (insn, REG_NONNEG, 0)"
- "...")
-
- The other two special looping patterns, `doloop_begin' and
-`doloop_end', are emitted by the loop optimizer for certain
-well-behaved loops with a finite number of loop iterations using
-information collected during strength reduction.
-
- The `doloop_end' pattern describes the actual looping instruction
-(or the implicit looping operation) and the `doloop_begin' pattern is
-an optional companion pattern that can be used for initialization
-needed for some low-overhead looping instructions.
-
- Note that some machines require the actual looping instruction to be
-emitted at the top of the loop (e.g., the TMS320C3x/C4x DSPs). Emitting
-the true RTL for a looping instruction at the top of the loop can cause
-problems with flow analysis. So instead, a dummy `doloop' insn is
-emitted at the end of the loop. The machine dependent reorg pass checks
-for the presence of this `doloop' insn and then searches back to the
-top of the loop, where it inserts the true looping insn (provided there
-are no instructions in the loop which would cause problems). Any
-additional labels can be emitted at this point. In addition, if the
-desired special iteration counter register was not allocated, this
-machine dependent reorg pass could emit a traditional compare and jump
-instruction pair.
-
- The essential difference between the
-`decrement_and_branch_until_zero' and the `doloop_end' patterns is that
-the loop optimizer allocates an additional pseudo register for the
-latter as an iteration counter. This pseudo register cannot be used
-within the loop (i.e., general induction variables cannot be derived
-from it), however, in many cases the loop induction variable may become
-redundant and removed by the flow pass.
-
-\1f
-File: gccint.info, Node: Insn Canonicalizations, Next: Expander Definitions, Prev: Looping Patterns, Up: Machine Desc
-
-Canonicalization of Instructions
-================================
-
- There are often cases where multiple RTL expressions could represent
-an operation performed by a single machine instruction. This situation
-is most commonly encountered with logical, branch, and
-multiply-accumulate instructions. In such cases, the compiler attempts
-to convert these multiple RTL expressions into a single canonical form
-to reduce the number of insn patterns required.
-
- In addition to algebraic simplifications, following canonicalizations
-are performed:
-
- * For commutative and comparison operators, a constant is always
- made the second operand. If a machine only supports a constant as
- the second operand, only patterns that match a constant in the
- second operand need be supplied.
-
- For these operators, if only one operand is a `neg', `not',
- `mult', `plus', or `minus' expression, it will be the first
- operand.
-
- * For the `compare' operator, a constant is always the second operand
- on machines where `cc0' is used (*note Jump Patterns::). On other
- machines, there are rare cases where the compiler might want to
- construct a `compare' with a constant as the first operand.
- However, these cases are not common enough for it to be worthwhile
- to provide a pattern matching a constant as the first operand
- unless the machine actually has such an instruction.
-
- An operand of `neg', `not', `mult', `plus', or `minus' is made the
- first operand under the same conditions as above.
-
- * `(minus X (const_int N))' is converted to `(plus X (const_int
- -N))'.
-
- * Within address computations (i.e., inside `mem'), a left shift is
- converted into the appropriate multiplication by a power of two.
-
- * De`Morgan's Law is used to move bitwise negation inside a bitwise
- logical-and or logical-or operation. If this results in only one
- operand being a `not' expression, it will be the first one.
-
- A machine that has an instruction that performs a bitwise
- logical-and of one operand with the bitwise negation of the other
- should specify the pattern for that instruction as
-
- (define_insn ""
- [(set (match_operand:M 0 ...)
- (and:M (not:M (match_operand:M 1 ...))
- (match_operand:M 2 ...)))]
- "..."
- "...")
-
- Similarly, a pattern for a "NAND" instruction should be written
-
- (define_insn ""
- [(set (match_operand:M 0 ...)
- (ior:M (not:M (match_operand:M 1 ...))
- (not:M (match_operand:M 2 ...))))]
- "..."
- "...")
-
- In both cases, it is not necessary to include patterns for the many
- logically equivalent RTL expressions.
-
- * The only possible RTL expressions involving both bitwise
- exclusive-or and bitwise negation are `(xor:M X Y)' and `(not:M
- (xor:M X Y))'.
-
- * The sum of three items, one of which is a constant, will only
- appear in the form
-
- (plus:M (plus:M X Y) CONSTANT)
-
- * On machines that do not use `cc0', `(compare X (const_int 0))'
- will be converted to X.
-
- * Equality comparisons of a group of bits (usually a single bit)
- with zero will be written using `zero_extract' rather than the
- equivalent `and' or `sign_extract' operations.
-
-
-\1f
-File: gccint.info, Node: Expander Definitions, Next: Insn Splitting, Prev: Insn Canonicalizations, Up: Machine Desc
-
-Defining RTL Sequences for Code Generation
-==========================================
-
- On some target machines, some standard pattern names for RTL
-generation cannot be handled with single insn, but a sequence of RTL
-insns can represent them. For these target machines, you can write a
-`define_expand' to specify how to generate the sequence of RTL.
-
- A `define_expand' is an RTL expression that looks almost like a
-`define_insn'; but, unlike the latter, a `define_expand' is used only
-for RTL generation and it can produce more than one RTL insn.
-
- A `define_expand' RTX has four operands:
-
- * The name. Each `define_expand' must have a name, since the only
- use for it is to refer to it by name.
-
- * The RTL template. This is a vector of RTL expressions representing
- a sequence of separate instructions. Unlike `define_insn', there
- is no implicit surrounding `PARALLEL'.
-
- * The condition, a string containing a C expression. This
- expression is used to express how the availability of this pattern
- depends on subclasses of target machine, selected by command-line
- options when GCC is run. This is just like the condition of a
- `define_insn' that has a standard name. Therefore, the condition
- (if present) may not depend on the data in the insn being matched,
- but only the target-machine-type flags. The compiler needs to
- test these conditions during initialization in order to learn
- exactly which named instructions are available in a particular run.
-
- * The preparation statements, a string containing zero or more C
- statements which are to be executed before RTL code is generated
- from the RTL template.
-
- Usually these statements prepare temporary registers for use as
- internal operands in the RTL template, but they can also generate
- RTL insns directly by calling routines such as `emit_insn', etc.
- Any such insns precede the ones that come from the RTL template.
-
- Every RTL insn emitted by a `define_expand' must match some
-`define_insn' in the machine description. Otherwise, the compiler will
-crash when trying to generate code for the insn or trying to optimize
-it.
-
- The RTL template, in addition to controlling generation of RTL insns,
-also describes the operands that need to be specified when this pattern
-is used. In particular, it gives a predicate for each operand.
-
- A true operand, which needs to be specified in order to generate RTL
-from the pattern, should be described with a `match_operand' in its
-first occurrence in the RTL template. This enters information on the
-operand's predicate into the tables that record such things. GCC uses
-the information to preload the operand into a register if that is
-required for valid RTL code. If the operand is referred to more than
-once, subsequent references should use `match_dup'.
-
- The RTL template may also refer to internal "operands" which are
-temporary registers or labels used only within the sequence made by the
-`define_expand'. Internal operands are substituted into the RTL
-template with `match_dup', never with `match_operand'. The values of
-the internal operands are not passed in as arguments by the compiler
-when it requests use of this pattern. Instead, they are computed
-within the pattern, in the preparation statements. These statements
-compute the values and store them into the appropriate elements of
-`operands' so that `match_dup' can find them.
-
- There are two special macros defined for use in the preparation
-statements: `DONE' and `FAIL'. Use them with a following semicolon, as
-a statement.
-
-`DONE'
- Use the `DONE' macro to end RTL generation for the pattern. The
- only RTL insns resulting from the pattern on this occasion will be
- those already emitted by explicit calls to `emit_insn' within the
- preparation statements; the RTL template will not be generated.
-
-`FAIL'
- Make the pattern fail on this occasion. When a pattern fails, it
- means that the pattern was not truly available. The calling
- routines in the compiler will try other strategies for code
- generation using other patterns.
-
- Failure is currently supported only for binary (addition,
- multiplication, shifting, etc.) and bit-field (`extv', `extzv',
- and `insv') operations.
-
- If the preparation falls through (invokes neither `DONE' nor
-`FAIL'), then the `define_expand' acts like a `define_insn' in that the
-RTL template is used to generate the insn.
-
- The RTL template is not used for matching, only for generating the
-initial insn list. If the preparation statement always invokes `DONE'
-or `FAIL', the RTL template may be reduced to a simple list of
-operands, such as this example:
-
- (define_expand "addsi3"
- [(match_operand:SI 0 "register_operand" "")
- (match_operand:SI 1 "register_operand" "")
- (match_operand:SI 2 "register_operand" "")]
- ""
- "
- {
- handle_add (operands[0], operands[1], operands[2]);
- DONE;
- }")
-
- Here is an example, the definition of left-shift for the SPUR chip:
-
- (define_expand "ashlsi3"
- [(set (match_operand:SI 0 "register_operand" "")
- (ashift:SI
- (match_operand:SI 1 "register_operand" "")
- (match_operand:SI 2 "nonmemory_operand" "")))]
- ""
- "
-
- {
- if (GET_CODE (operands[2]) != CONST_INT
- || (unsigned) INTVAL (operands[2]) > 3)
- FAIL;
- }")
-
-This example uses `define_expand' so that it can generate an RTL insn
-for shifting when the shift-count is in the supported range of 0 to 3
-but fail in other cases where machine insns aren't available. When it
-fails, the compiler tries another strategy using different patterns
-(such as, a library call).
-
- If the compiler were able to handle nontrivial condition-strings in
-patterns with names, then it would be possible to use a `define_insn'
-in that case. Here is another case (zero-extension on the 68000) which
-makes more use of the power of `define_expand':
-
- (define_expand "zero_extendhisi2"
- [(set (match_operand:SI 0 "general_operand" "")
- (const_int 0))
- (set (strict_low_part
- (subreg:HI
- (match_dup 0)
- 0))
- (match_operand:HI 1 "general_operand" ""))]
- ""
- "operands[1] = make_safe_from (operands[1], operands[0]);")
-
-Here two RTL insns are generated, one to clear the entire output operand
-and the other to copy the input operand into its low half. This
-sequence is incorrect if the input operand refers to [the old value of]
-the output operand, so the preparation statement makes sure this isn't
-so. The function `make_safe_from' copies the `operands[1]' into a
-temporary register if it refers to `operands[0]'. It does this by
-emitting another RTL insn.
-
- Finally, a third example shows the use of an internal operand.
-Zero-extension on the SPUR chip is done by `and'-ing the result against
-a halfword mask. But this mask cannot be represented by a `const_int'
-because the constant value is too large to be legitimate on this
-machine. So it must be copied into a register with `force_reg' and
-then the register used in the `and'.
-
- (define_expand "zero_extendhisi2"
- [(set (match_operand:SI 0 "register_operand" "")
- (and:SI (subreg:SI
- (match_operand:HI 1 "register_operand" "")
- 0)
- (match_dup 2)))]
- ""
- "operands[2]
- = force_reg (SImode, GEN_INT (65535)); ")
-
- *Note:* If the `define_expand' is used to serve a standard binary or
-unary arithmetic operation or a bit-field operation, then the last insn
-it generates must not be a `code_label', `barrier' or `note'. It must
-be an `insn', `jump_insn' or `call_insn'. If you don't need a real insn
-at the end, emit an insn to copy the result of the operation into
-itself. Such an insn will generate no code, but it can avoid problems
-in the compiler.
-
-\1f
-File: gccint.info, Node: Insn Splitting, Next: Including Patterns, Prev: Expander Definitions, Up: Machine Desc
-
-Defining How to Split Instructions
-==================================
-
- There are two cases where you should specify how to split a pattern
-into multiple insns. On machines that have instructions requiring delay
-slots (*note Delay Slots::) or that have instructions whose output is
-not available for multiple cycles (*note Function Units::), the compiler
-phases that optimize these cases need to be able to move insns into
-one-instruction delay slots. However, some insns may generate more
-than one machine instruction. These insns cannot be placed into a
-delay slot.
-
- Often you can rewrite the single insn as a list of individual insns,
-each corresponding to one machine instruction. The disadvantage of
-doing so is that it will cause the compilation to be slower and require
-more space. If the resulting insns are too complex, it may also
-suppress some optimizations. The compiler splits the insn if there is a
-reason to believe that it might improve instruction or delay slot
-scheduling.
-
- The insn combiner phase also splits putative insns. If three insns
-are merged into one insn with a complex expression that cannot be
-matched by some `define_insn' pattern, the combiner phase attempts to
-split the complex pattern into two insns that are recognized. Usually
-it can break the complex pattern into two patterns by splitting out some
-subexpression. However, in some other cases, such as performing an
-addition of a large constant in two insns on a RISC machine, the way to
-split the addition into two insns is machine-dependent.
-
- The `define_split' definition tells the compiler how to split a
-complex insn into several simpler insns. It looks like this:
-
- (define_split
- [INSN-PATTERN]
- "CONDITION"
- [NEW-INSN-PATTERN-1
- NEW-INSN-PATTERN-2
- ...]
- "PREPARATION-STATEMENTS")
-
- INSN-PATTERN is a pattern that needs to be split and CONDITION is
-the final condition to be tested, as in a `define_insn'. When an insn
-matching INSN-PATTERN and satisfying CONDITION is found, it is replaced
-in the insn list with the insns given by NEW-INSN-PATTERN-1,
-NEW-INSN-PATTERN-2, etc.
-
- The PREPARATION-STATEMENTS are similar to those statements that are
-specified for `define_expand' (*note Expander Definitions::) and are
-executed before the new RTL is generated to prepare for the generated
-code or emit some insns whose pattern is not fixed. Unlike those in
-`define_expand', however, these statements must not generate any new
-pseudo-registers. Once reload has completed, they also must not
-allocate any space in the stack frame.
-
- Patterns are matched against INSN-PATTERN in two different
-circumstances. If an insn needs to be split for delay slot scheduling
-or insn scheduling, the insn is already known to be valid, which means
-that it must have been matched by some `define_insn' and, if
-`reload_completed' is nonzero, is known to satisfy the constraints of
-that `define_insn'. In that case, the new insn patterns must also be
-insns that are matched by some `define_insn' and, if `reload_completed'
-is nonzero, must also satisfy the constraints of those definitions.
-
- As an example of this usage of `define_split', consider the following
-example from `a29k.md', which splits a `sign_extend' from `HImode' to
-`SImode' into a pair of shift insns:
-
- (define_split
- [(set (match_operand:SI 0 "gen_reg_operand" "")
- (sign_extend:SI (match_operand:HI 1 "gen_reg_operand" "")))]
- ""
- [(set (match_dup 0)
- (ashift:SI (match_dup 1)
- (const_int 16)))
- (set (match_dup 0)
- (ashiftrt:SI (match_dup 0)
- (const_int 16)))]
- "
- { operands[1] = gen_lowpart (SImode, operands[1]); }")
-
- When the combiner phase tries to split an insn pattern, it is always
-the case that the pattern is _not_ matched by any `define_insn'. The
-combiner pass first tries to split a single `set' expression and then
-the same `set' expression inside a `parallel', but followed by a
-`clobber' of a pseudo-reg to use as a scratch register. In these
-cases, the combiner expects exactly two new insn patterns to be
-generated. It will verify that these patterns match some `define_insn'
-definitions, so you need not do this test in the `define_split' (of
-course, there is no point in writing a `define_split' that will never
-produce insns that match).
-
- Here is an example of this use of `define_split', taken from
-`rs6000.md':
-
- (define_split
- [(set (match_operand:SI 0 "gen_reg_operand" "")
- (plus:SI (match_operand:SI 1 "gen_reg_operand" "")
- (match_operand:SI 2 "non_add_cint_operand" "")))]
- ""
- [(set (match_dup 0) (plus:SI (match_dup 1) (match_dup 3)))
- (set (match_dup 0) (plus:SI (match_dup 0) (match_dup 4)))]
- "
- {
- int low = INTVAL (operands[2]) & 0xffff;
- int high = (unsigned) INTVAL (operands[2]) >> 16;
-
- if (low & 0x8000)
- high++, low |= 0xffff0000;
-
- operands[3] = GEN_INT (high << 16);
- operands[4] = GEN_INT (low);
- }")
-
- Here the predicate `non_add_cint_operand' matches any `const_int'
-that is _not_ a valid operand of a single add insn. The add with the
-smaller displacement is written so that it can be substituted into the
-address of a subsequent operation.
-
- An example that uses a scratch register, from the same file,
-generates an equality comparison of a register and a large constant:
-
- (define_split
- [(set (match_operand:CC 0 "cc_reg_operand" "")
- (compare:CC (match_operand:SI 1 "gen_reg_operand" "")
- (match_operand:SI 2 "non_short_cint_operand" "")))
- (clobber (match_operand:SI 3 "gen_reg_operand" ""))]
- "find_single_use (operands[0], insn, 0)
- && (GET_CODE (*find_single_use (operands[0], insn, 0)) == EQ
- || GET_CODE (*find_single_use (operands[0], insn, 0)) == NE)"
- [(set (match_dup 3) (xor:SI (match_dup 1) (match_dup 4)))
- (set (match_dup 0) (compare:CC (match_dup 3) (match_dup 5)))]
- "
- {
- /* Get the constant we are comparing against, C, and see what it
- looks like sign-extended to 16 bits. Then see what constant
- could be XOR'ed with C to get the sign-extended value. */
-
- int c = INTVAL (operands[2]);
- int sextc = (c << 16) >> 16;
- int xorv = c ^ sextc;
-
- operands[4] = GEN_INT (xorv);
- operands[5] = GEN_INT (sextc);
- }")
-
- To avoid confusion, don't write a single `define_split' that accepts
-some insns that match some `define_insn' as well as some insns that
-don't. Instead, write two separate `define_split' definitions, one for
-the insns that are valid and one for the insns that are not valid.
-
- The splitter is allowed to split jump instructions into sequence of
-jumps or create new jumps in while splitting non-jump instructions. As
-the central flowgraph and branch prediction information needs to be
-updated, several restriction apply.
-
- Splitting of jump instruction into sequence that over by another jump
-instruction is always valid, as compiler expect identical behavior of
-new jump. When new sequence contains multiple jump instructions or new
-labels, more assistance is needed. Splitter is required to create only
-unconditional jumps, or simple conditional jump instructions.
-Additionally it must attach a `REG_BR_PROB' note to each conditional
-jump. An global variable `split_branch_probability' hold the
-probability of original branch in case it was an simple conditional
-jump, -1 otherwise. To simplify recomputing of edge frequencies, new
-sequence is required to have only forward jumps to the newly created
-labels.
-
- For the common case where the pattern of a define_split exactly
-matches the pattern of a define_insn, use `define_insn_and_split'. It
-looks like this:
-
- (define_insn_and_split
- [INSN-PATTERN]
- "CONDITION"
- "OUTPUT-TEMPLATE"
- "SPLIT-CONDITION"
- [NEW-INSN-PATTERN-1
- NEW-INSN-PATTERN-2
- ...]
- "PREPARATION-STATEMENTS"
- [INSN-ATTRIBUTES])
-
- INSN-PATTERN, CONDITION, OUTPUT-TEMPLATE, and INSN-ATTRIBUTES are
-used as in `define_insn'. The NEW-INSN-PATTERN vector and the
-PREPARATION-STATEMENTS are used as in a `define_split'. The
-SPLIT-CONDITION is also used as in `define_split', with the additional
-behavior that if the condition starts with `&&', the condition used for
-the split will be the constructed as a logical "and" of the split
-condition with the insn condition. For example, from i386.md:
-
- (define_insn_and_split "zero_extendhisi2_and"
- [(set (match_operand:SI 0 "register_operand" "=r")
- (zero_extend:SI (match_operand:HI 1 "register_operand" "0")))
- (clobber (reg:CC 17))]
- "TARGET_ZERO_EXTEND_WITH_AND && !optimize_size"
- "#"
- "&& reload_completed"
- [(parallel [(set (match_dup 0)
- (and:SI (match_dup 0) (const_int 65535)))
- (clobber (reg:CC 17))])]
- ""
- [(set_attr "type" "alu1")])
-
- In this case, the actual split condition will be
-`TARGET_ZERO_EXTEND_WITH_AND && !optimize_size && reload_completed'.
-
- The `define_insn_and_split' construction provides exactly the same
-functionality as two separate `define_insn' and `define_split'
-patterns. It exists for compactness, and as a maintenance tool to
-prevent having to ensure the two patterns' templates match.
-
-\1f
-File: gccint.info, Node: Including Patterns, Next: Peephole Definitions, Prev: Insn Splitting, Up: Machine Desc
-
-Including Patterns in Machine Descriptions.
-===========================================
-
- The `include' pattern tells the compiler tools where to look for
-patterns that are in files other than in the file `.md'. This is used
-only at build time and there is no preprocessing allowed.
-
- It looks like:
-
-
- (include
- PATHNAME)
-
- For example:
-
-
- (include "filestuff")
-
- Where PATHNAME is a string that specifies the the location of the
-file, specifies the include file to be in
-`gcc/config/target/filestuff'. The directory `gcc/config/target' is
-regarded as the default directory.
-
- Machine descriptions may be split up into smaller more manageable
-subsections and placed into subdirectories.
-
- By specifying:
-
-
- (include "BOGUS/filestuff")
-
- the include file is specified to be in
-`gcc/config/TARGET/BOGUS/filestuff'.
-
- Specifying an absolute path for the include file such as;
-
- (include "/u2/BOGUS/filestuff")
- is permitted but is not encouraged.
-
-RTL Generation Tool Options for Directory Search
-------------------------------------------------
-
- The `-IDIR' option specifies directories to search for machine
-descriptions. For example:
-
-
- genrecog -I/p1/abc/proc1 -I/p2/abcd/pro2 target.md
-
- Add the directory DIR to the head of the list of directories to be
-searched for header files. This can be used to override a system
-machine definition file, substituting your own version, since these
-directories are searched before the default machine description file
-directories. If you use more than one `-I' option, the directories are
-scanned in left-to-right order; the standard default directory come
-after.
-
-\1f
-File: gccint.info, Node: Peephole Definitions, Next: Insn Attributes, Prev: Including Patterns, Up: Machine Desc
-
-Machine-Specific Peephole Optimizers
-====================================
-
- In addition to instruction patterns the `md' file may contain
-definitions of machine-specific peephole optimizations.
-
- The combiner does not notice certain peephole optimizations when the
-data flow in the program does not suggest that it should try them. For
-example, sometimes two consecutive insns related in purpose can be
-combined even though the second one does not appear to use a register
-computed in the first one. A machine-specific peephole optimizer can
-detect such opportunities.
-
- There are two forms of peephole definitions that may be used. The
-original `define_peephole' is run at assembly output time to match
-insns and substitute assembly text. Use of `define_peephole' is
-deprecated.
-
- A newer `define_peephole2' matches insns and substitutes new insns.
-The `peephole2' pass is run after register allocation but before
-scheduling, which may result in much better code for targets that do
-scheduling.
-
-* Menu:
-
-* define_peephole:: RTL to Text Peephole Optimizers
-* define_peephole2:: RTL to RTL Peephole Optimizers
-
-\1f
-File: gccint.info, Node: define_peephole, Next: define_peephole2, Up: Peephole Definitions
-
-RTL to Text Peephole Optimizers
--------------------------------
-
- A definition looks like this:
-
- (define_peephole
- [INSN-PATTERN-1
- INSN-PATTERN-2
- ...]
- "CONDITION"
- "TEMPLATE"
- "OPTIONAL-INSN-ATTRIBUTES")
-
-The last string operand may be omitted if you are not using any
-machine-specific information in this machine description. If present,
-it must obey the same rules as in a `define_insn'.
-
- In this skeleton, INSN-PATTERN-1 and so on are patterns to match
-consecutive insns. The optimization applies to a sequence of insns when
-INSN-PATTERN-1 matches the first one, INSN-PATTERN-2 matches the next,
-and so on.
-
- Each of the insns matched by a peephole must also match a
-`define_insn'. Peepholes are checked only at the last stage just
-before code generation, and only optionally. Therefore, any insn which
-would match a peephole but no `define_insn' will cause a crash in code
-generation in an unoptimized compilation, or at various optimization
-stages.
-
- The operands of the insns are matched with `match_operands',
-`match_operator', and `match_dup', as usual. What is not usual is that
-the operand numbers apply to all the insn patterns in the definition.
-So, you can check for identical operands in two insns by using
-`match_operand' in one insn and `match_dup' in the other.
-
- The operand constraints used in `match_operand' patterns do not have
-any direct effect on the applicability of the peephole, but they will
-be validated afterward, so make sure your constraints are general enough
-to apply whenever the peephole matches. If the peephole matches but
-the constraints are not satisfied, the compiler will crash.
-
- It is safe to omit constraints in all the operands of the peephole;
-or you can write constraints which serve as a double-check on the
-criteria previously tested.
-
- Once a sequence of insns matches the patterns, the CONDITION is
-checked. This is a C expression which makes the final decision whether
-to perform the optimization (we do so if the expression is nonzero). If
-CONDITION is omitted (in other words, the string is empty) then the
-optimization is applied to every sequence of insns that matches the
-patterns.
-
- The defined peephole optimizations are applied after register
-allocation is complete. Therefore, the peephole definition can check
-which operands have ended up in which kinds of registers, just by
-looking at the operands.
-
- The way to refer to the operands in CONDITION is to write
-`operands[I]' for operand number I (as matched by `(match_operand I
-...)'). Use the variable `insn' to refer to the last of the insns
-being matched; use `prev_active_insn' to find the preceding insns.
-
- When optimizing computations with intermediate results, you can use
-CONDITION to match only when the intermediate results are not used
-elsewhere. Use the C expression `dead_or_set_p (INSN, OP)', where INSN
-is the insn in which you expect the value to be used for the last time
-(from the value of `insn', together with use of `prev_nonnote_insn'),
-and OP is the intermediate value (from `operands[I]').
-
- Applying the optimization means replacing the sequence of insns with
-one new insn. The TEMPLATE controls ultimate output of assembler code
-for this combined insn. It works exactly like the template of a
-`define_insn'. Operand numbers in this template are the same ones used
-in matching the original sequence of insns.
-
- The result of a defined peephole optimizer does not need to match
-any of the insn patterns in the machine description; it does not even
-have an opportunity to match them. The peephole optimizer definition
-itself serves as the insn pattern to control how the insn is output.
-
- Defined peephole optimizers are run as assembler code is being
-output, so the insns they produce are never combined or rearranged in
-any way.
-
- Here is an example, taken from the 68000 machine description:
-
- (define_peephole
- [(set (reg:SI 15) (plus:SI (reg:SI 15) (const_int 4)))
- (set (match_operand:DF 0 "register_operand" "=f")
- (match_operand:DF 1 "register_operand" "ad"))]
- "FP_REG_P (operands[0]) && ! FP_REG_P (operands[1])"
- {
- rtx xoperands[2];
- xoperands[1] = gen_rtx (REG, SImode, REGNO (operands[1]) + 1);
- #ifdef MOTOROLA
- output_asm_insn ("move.l %1,(sp)", xoperands);
- output_asm_insn ("move.l %1,-(sp)", operands);
- return "fmove.d (sp)+,%0";
- #else
- output_asm_insn ("movel %1,sp@", xoperands);
- output_asm_insn ("movel %1,sp@-", operands);
- return "fmoved sp@+,%0";
- #endif
- })
-
- The effect of this optimization is to change
-
- jbsr _foobar
- addql #4,sp
- movel d1,sp@-
- movel d0,sp@-
- fmoved sp@+,fp0
-
-into
-
- jbsr _foobar
- movel d1,sp@
- movel d0,sp@-
- fmoved sp@+,fp0
-
- INSN-PATTERN-1 and so on look _almost_ like the second operand of
-`define_insn'. There is one important difference: the second operand
-of `define_insn' consists of one or more RTX's enclosed in square
-brackets. Usually, there is only one: then the same action can be
-written as an element of a `define_peephole'. But when there are
-multiple actions in a `define_insn', they are implicitly enclosed in a
-`parallel'. Then you must explicitly write the `parallel', and the
-square brackets within it, in the `define_peephole'. Thus, if an insn
-pattern looks like this,
-
- (define_insn "divmodsi4"
- [(set (match_operand:SI 0 "general_operand" "=d")
- (div:SI (match_operand:SI 1 "general_operand" "0")
- (match_operand:SI 2 "general_operand" "dmsK")))
- (set (match_operand:SI 3 "general_operand" "=d")
- (mod:SI (match_dup 1) (match_dup 2)))]
- "TARGET_68020"
- "divsl%.l %2,%3:%0")
-
-then the way to mention this insn in a peephole is as follows:
-
- (define_peephole
- [...
- (parallel
- [(set (match_operand:SI 0 "general_operand" "=d")
- (div:SI (match_operand:SI 1 "general_operand" "0")
- (match_operand:SI 2 "general_operand" "dmsK")))
- (set (match_operand:SI 3 "general_operand" "=d")
- (mod:SI (match_dup 1) (match_dup 2)))])
- ...]
- ...)
-
-\1f
-File: gccint.info, Node: define_peephole2, Prev: define_peephole, Up: Peephole Definitions
-
-RTL to RTL Peephole Optimizers
-------------------------------
-
- The `define_peephole2' definition tells the compiler how to
-substitute one sequence of instructions for another sequence, what
-additional scratch registers may be needed and what their lifetimes
-must be.
-
- (define_peephole2
- [INSN-PATTERN-1
- INSN-PATTERN-2
- ...]
- "CONDITION"
- [NEW-INSN-PATTERN-1
- NEW-INSN-PATTERN-2
- ...]
- "PREPARATION-STATEMENTS")
-
- The definition is almost identical to `define_split' (*note Insn
-Splitting::) except that the pattern to match is not a single
-instruction, but a sequence of instructions.
-
- It is possible to request additional scratch registers for use in the
-output template. If appropriate registers are not free, the pattern
-will simply not match.
-
- Scratch registers are requested with a `match_scratch' pattern at
-the top level of the input pattern. The allocated register (initially)
-will be dead at the point requested within the original sequence. If
-the scratch is used at more than a single point, a `match_dup' pattern
-at the top level of the input pattern marks the last position in the
-input sequence at which the register must be available.
-
- Here is an example from the IA-32 machine description:
-
- (define_peephole2
- [(match_scratch:SI 2 "r")
- (parallel [(set (match_operand:SI 0 "register_operand" "")
- (match_operator:SI 3 "arith_or_logical_operator"
- [(match_dup 0)
- (match_operand:SI 1 "memory_operand" "")]))
- (clobber (reg:CC 17))])]
- "! optimize_size && ! TARGET_READ_MODIFY"
- [(set (match_dup 2) (match_dup 1))
- (parallel [(set (match_dup 0)
- (match_op_dup 3 [(match_dup 0) (match_dup 2)]))
- (clobber (reg:CC 17))])]
- "")
-
-This pattern tries to split a load from its use in the hopes that we'll
-be able to schedule around the memory load latency. It allocates a
-single `SImode' register of class `GENERAL_REGS' (`"r"') that needs to
-be live only at the point just before the arithmetic.
-
- A real example requiring extended scratch lifetimes is harder to
-come by, so here's a silly made-up example:
-
- (define_peephole2
- [(match_scratch:SI 4 "r")
- (set (match_operand:SI 0 "" "") (match_operand:SI 1 "" ""))
- (set (match_operand:SI 2 "" "") (match_dup 1))
- (match_dup 4)
- (set (match_operand:SI 3 "" "") (match_dup 1))]
- "/* determine 1 does not overlap 0 and 2 */"
- [(set (match_dup 4) (match_dup 1))
- (set (match_dup 0) (match_dup 4))
- (set (match_dup 2) (match_dup 4))]
- (set (match_dup 3) (match_dup 4))]
- "")
-
-If we had not added the `(match_dup 4)' in the middle of the input
-sequence, it might have been the case that the register we chose at the
-beginning of the sequence is killed by the first or second `set'.
-
-\1f
-File: gccint.info, Node: Insn Attributes, Next: Conditional Execution, Prev: Peephole Definitions, Up: Machine Desc
-
-Instruction Attributes
-======================
-
- In addition to describing the instruction supported by the target
-machine, the `md' file also defines a group of "attributes" and a set of
-values for each. Every generated insn is assigned a value for each
-attribute. One possible attribute would be the effect that the insn
-has on the machine's condition code. This attribute can then be used
-by `NOTICE_UPDATE_CC' to track the condition codes.
-
-* Menu:
-
-* Defining Attributes:: Specifying attributes and their values.
-* Expressions:: Valid expressions for attribute values.
-* Tagging Insns:: Assigning attribute values to insns.
-* Attr Example:: An example of assigning attributes.
-* Insn Lengths:: Computing the length of insns.
-* Constant Attributes:: Defining attributes that are constant.
-* Delay Slots:: Defining delay slots required for a machine.
-* Function Units:: Specifying information for insn scheduling.
-
-\1f
-File: gccint.info, Node: Defining Attributes, Next: Expressions, Up: Insn Attributes
-
-Defining Attributes and their Values
-------------------------------------
-
- The `define_attr' expression is used to define each attribute
-required by the target machine. It looks like:
-
- (define_attr NAME LIST-OF-VALUES DEFAULT)
-
- NAME is a string specifying the name of the attribute being defined.
-
- LIST-OF-VALUES is either a string that specifies a comma-separated
-list of values that can be assigned to the attribute, or a null string
-to indicate that the attribute takes numeric values.
-
- DEFAULT is an attribute expression that gives the value of this
-attribute for insns that match patterns whose definition does not
-include an explicit value for this attribute. *Note Attr Example::,
-for more information on the handling of defaults. *Note Constant
-Attributes::, for information on attributes that do not depend on any
-particular insn.
-
- For each defined attribute, a number of definitions are written to
-the `insn-attr.h' file. For cases where an explicit set of values is
-specified for an attribute, the following are defined:
-
- * A `#define' is written for the symbol `HAVE_ATTR_NAME'.
-
- * An enumeral class is defined for `attr_NAME' with elements of the
- form `UPPER-NAME_UPPER-VALUE' where the attribute name and value
- are first converted to upper case.
-
- * A function `get_attr_NAME' is defined that is passed an insn and
- returns the attribute value for that insn.
-
- For example, if the following is present in the `md' file:
-
- (define_attr "type" "branch,fp,load,store,arith" ...)
-
-the following lines will be written to the file `insn-attr.h'.
-
- #define HAVE_ATTR_type
- enum attr_type {TYPE_BRANCH, TYPE_FP, TYPE_LOAD,
- TYPE_STORE, TYPE_ARITH};
- extern enum attr_type get_attr_type ();
-
- If the attribute takes numeric values, no `enum' type will be
-defined and the function to obtain the attribute's value will return
-`int'.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Expressions, Next: Tagging Insns, Prev: Defining Attributes, Up: Insn Attributes
-
-Attribute Expressions
----------------------
-
- RTL expressions used to define attributes use the codes described
-above plus a few specific to attribute definitions, to be discussed
-below. Attribute value expressions must have one of the following
-forms:
-
-`(const_int I)'
- The integer I specifies the value of a numeric attribute. I must
- be non-negative.
-
- The value of a numeric attribute can be specified either with a
- `const_int', or as an integer represented as a string in
- `const_string', `eq_attr' (see below), `attr', `symbol_ref',
- simple arithmetic expressions, and `set_attr' overrides on
- specific instructions (*note Tagging Insns::).
-
-`(const_string VALUE)'
- The string VALUE specifies a constant attribute value. If VALUE
- is specified as `"*"', it means that the default value of the
- attribute is to be used for the insn containing this expression.
- `"*"' obviously cannot be used in the DEFAULT expression of a
- `define_attr'.
-
- If the attribute whose value is being specified is numeric, VALUE
- must be a string containing a non-negative integer (normally
- `const_int' would be used in this case). Otherwise, it must
- contain one of the valid values for the attribute.
-
-`(if_then_else TEST TRUE-VALUE FALSE-VALUE)'
- TEST specifies an attribute test, whose format is defined below.
- The value of this expression is TRUE-VALUE if TEST is true,
- otherwise it is FALSE-VALUE.
-
-`(cond [TEST1 VALUE1 ...] DEFAULT)'
- The first operand of this expression is a vector containing an even
- number of expressions and consisting of pairs of TEST and VALUE
- expressions. The value of the `cond' expression is that of the
- VALUE corresponding to the first true TEST expression. If none of
- the TEST expressions are true, the value of the `cond' expression
- is that of the DEFAULT expression.
-
- TEST expressions can have one of the following forms:
-
-`(const_int I)'
- This test is true if I is nonzero and false otherwise.
-
-`(not TEST)'
-`(ior TEST1 TEST2)'
-`(and TEST1 TEST2)'
- These tests are true if the indicated logical function is true.
-
-`(match_operand:M N PRED CONSTRAINTS)'
- This test is true if operand N of the insn whose attribute value
- is being determined has mode M (this part of the test is ignored
- if M is `VOIDmode') and the function specified by the string PRED
- returns a nonzero value when passed operand N and mode M (this
- part of the test is ignored if PRED is the null string).
-
- The CONSTRAINTS operand is ignored and should be the null string.
-
-`(le ARITH1 ARITH2)'
-`(leu ARITH1 ARITH2)'
-`(lt ARITH1 ARITH2)'
-`(ltu ARITH1 ARITH2)'
-`(gt ARITH1 ARITH2)'
-`(gtu ARITH1 ARITH2)'
-`(ge ARITH1 ARITH2)'
-`(geu ARITH1 ARITH2)'
-`(ne ARITH1 ARITH2)'
-`(eq ARITH1 ARITH2)'
- These tests are true if the indicated comparison of the two
- arithmetic expressions is true. Arithmetic expressions are formed
- with `plus', `minus', `mult', `div', `mod', `abs', `neg', `and',
- `ior', `xor', `not', `ashift', `lshiftrt', and `ashiftrt'
- expressions.
-
- `const_int' and `symbol_ref' are always valid terms (*note Insn
- Lengths::,for additional forms). `symbol_ref' is a string
- denoting a C expression that yields an `int' when evaluated by the
- `get_attr_...' routine. It should normally be a global variable.
-
-`(eq_attr NAME VALUE)'
- NAME is a string specifying the name of an attribute.
-
- VALUE is a string that is either a valid value for attribute NAME,
- a comma-separated list of values, or `!' followed by a value or
- list. If VALUE does not begin with a `!', this test is true if
- the value of the NAME attribute of the current insn is in the list
- specified by VALUE. If VALUE begins with a `!', this test is true
- if the attribute's value is _not_ in the specified list.
-
- For example,
-
- (eq_attr "type" "load,store")
-
- is equivalent to
-
- (ior (eq_attr "type" "load") (eq_attr "type" "store"))
-
- If NAME specifies an attribute of `alternative', it refers to the
- value of the compiler variable `which_alternative' (*note Output
- Statement::) and the values must be small integers. For example,
-
- (eq_attr "alternative" "2,3")
-
- is equivalent to
-
- (ior (eq (symbol_ref "which_alternative") (const_int 2))
- (eq (symbol_ref "which_alternative") (const_int 3)))
-
- Note that, for most attributes, an `eq_attr' test is simplified in
- cases where the value of the attribute being tested is known for
- all insns matching a particular pattern. This is by far the most
- common case.
-
-`(attr_flag NAME)'
- The value of an `attr_flag' expression is true if the flag
- specified by NAME is true for the `insn' currently being scheduled.
-
- NAME is a string specifying one of a fixed set of flags to test.
- Test the flags `forward' and `backward' to determine the direction
- of a conditional branch. Test the flags `very_likely', `likely',
- `very_unlikely', and `unlikely' to determine if a conditional
- branch is expected to be taken.
-
- If the `very_likely' flag is true, then the `likely' flag is also
- true. Likewise for the `very_unlikely' and `unlikely' flags.
-
- This example describes a conditional branch delay slot which can
- be nullified for forward branches that are taken (annul-true) or
- for backward branches which are not taken (annul-false).
-
- (define_delay (eq_attr "type" "cbranch")
- [(eq_attr "in_branch_delay" "true")
- (and (eq_attr "in_branch_delay" "true")
- (attr_flag "forward"))
- (and (eq_attr "in_branch_delay" "true")
- (attr_flag "backward"))])
-
- The `forward' and `backward' flags are false if the current `insn'
- being scheduled is not a conditional branch.
-
- The `very_likely' and `likely' flags are true if the `insn' being
- scheduled is not a conditional branch. The `very_unlikely' and
- `unlikely' flags are false if the `insn' being scheduled is not a
- conditional branch.
-
- `attr_flag' is only used during delay slot scheduling and has no
- meaning to other passes of the compiler.
-
-`(attr NAME)'
- The value of another attribute is returned. This is most useful
- for numeric attributes, as `eq_attr' and `attr_flag' produce more
- efficient code for non-numeric attributes.
-
-\1f
-File: gccint.info, Node: Tagging Insns, Next: Attr Example, Prev: Expressions, Up: Insn Attributes
-
-Assigning Attribute Values to Insns
------------------------------------
-
- The value assigned to an attribute of an insn is primarily
-determined by which pattern is matched by that insn (or which
-`define_peephole' generated it). Every `define_insn' and
-`define_peephole' can have an optional last argument to specify the
-values of attributes for matching insns. The value of any attribute
-not specified in a particular insn is set to the default value for that
-attribute, as specified in its `define_attr'. Extensive use of default
-values for attributes permits the specification of the values for only
-one or two attributes in the definition of most insn patterns, as seen
-in the example in the next section.
-
- The optional last argument of `define_insn' and `define_peephole' is
-a vector of expressions, each of which defines the value for a single
-attribute. The most general way of assigning an attribute's value is
-to use a `set' expression whose first operand is an `attr' expression
-giving the name of the attribute being set. The second operand of the
-`set' is an attribute expression (*note Expressions::) giving the value
-of the attribute.
-
- When the attribute value depends on the `alternative' attribute
-(i.e., which is the applicable alternative in the constraint of the
-insn), the `set_attr_alternative' expression can be used. It allows
-the specification of a vector of attribute expressions, one for each
-alternative.
-
- When the generality of arbitrary attribute expressions is not
-required, the simpler `set_attr' expression can be used, which allows
-specifying a string giving either a single attribute value or a list of
-attribute values, one for each alternative.
-
- The form of each of the above specifications is shown below. In
-each case, NAME is a string specifying the attribute to be set.
-
-`(set_attr NAME VALUE-STRING)'
- VALUE-STRING is either a string giving the desired attribute value,
- or a string containing a comma-separated list giving the values for
- succeeding alternatives. The number of elements must match the
- number of alternatives in the constraint of the insn pattern.
-
- Note that it may be useful to specify `*' for some alternative, in
- which case the attribute will assume its default value for insns
- matching that alternative.
-
-`(set_attr_alternative NAME [VALUE1 VALUE2 ...])'
- Depending on the alternative of the insn, the value will be one of
- the specified values. This is a shorthand for using a `cond' with
- tests on the `alternative' attribute.
-
-`(set (attr NAME) VALUE)'
- The first operand of this `set' must be the special RTL expression
- `attr', whose sole operand is a string giving the name of the
- attribute being set. VALUE is the value of the attribute.
-
- The following shows three different ways of representing the same
-attribute value specification:
-
- (set_attr "type" "load,store,arith")
-
- (set_attr_alternative "type"
- [(const_string "load") (const_string "store")
- (const_string "arith")])
-
- (set (attr "type")
- (cond [(eq_attr "alternative" "1") (const_string "load")
- (eq_attr "alternative" "2") (const_string "store")]
- (const_string "arith")))
-
- The `define_asm_attributes' expression provides a mechanism to
-specify the attributes assigned to insns produced from an `asm'
-statement. It has the form:
-
- (define_asm_attributes [ATTR-SETS])
-
-where ATTR-SETS is specified the same as for both the `define_insn' and
-the `define_peephole' expressions.
-
- These values will typically be the "worst case" attribute values.
-For example, they might indicate that the condition code will be
-clobbered.
-
- A specification for a `length' attribute is handled specially. The
-way to compute the length of an `asm' insn is to multiply the length
-specified in the expression `define_asm_attributes' by the number of
-machine instructions specified in the `asm' statement, determined by
-counting the number of semicolons and newlines in the string.
-Therefore, the value of the `length' attribute specified in a
-`define_asm_attributes' should be the maximum possible length of a
-single machine instruction.
-
-\1f
-File: gccint.info, Node: Attr Example, Next: Insn Lengths, Prev: Tagging Insns, Up: Insn Attributes
-
-Example of Attribute Specifications
------------------------------------
-
- The judicious use of defaulting is important in the efficient use of
-insn attributes. Typically, insns are divided into "types" and an
-attribute, customarily called `type', is used to represent this value.
-This attribute is normally used only to define the default value for
-other attributes. An example will clarify this usage.
-
- Assume we have a RISC machine with a condition code and in which only
-full-word operations are performed in registers. Let us assume that we
-can divide all insns into loads, stores, (integer) arithmetic
-operations, floating point operations, and branches.
-
- Here we will concern ourselves with determining the effect of an
-insn on the condition code and will limit ourselves to the following
-possible effects: The condition code can be set unpredictably
-(clobbered), not be changed, be set to agree with the results of the
-operation, or only changed if the item previously set into the
-condition code has been modified.
-
- Here is part of a sample `md' file for such a machine:
-
- (define_attr "type" "load,store,arith,fp,branch" (const_string "arith"))
-
- (define_attr "cc" "clobber,unchanged,set,change0"
- (cond [(eq_attr "type" "load")
- (const_string "change0")
- (eq_attr "type" "store,branch")
- (const_string "unchanged")
- (eq_attr "type" "arith")
- (if_then_else (match_operand:SI 0 "" "")
- (const_string "set")
- (const_string "clobber"))]
- (const_string "clobber")))
-
- (define_insn ""
- [(set (match_operand:SI 0 "general_operand" "=r,r,m")
- (match_operand:SI 1 "general_operand" "r,m,r"))]
- ""
- "@
- move %0,%1
- load %0,%1
- store %0,%1"
- [(set_attr "type" "arith,load,store")])
-
- Note that we assume in the above example that arithmetic operations
-performed on quantities smaller than a machine word clobber the
-condition code since they will set the condition code to a value
-corresponding to the full-word result.
-
-\1f
-File: gccint.info, Node: Insn Lengths, Next: Constant Attributes, Prev: Attr Example, Up: Insn Attributes
-
-Computing the Length of an Insn
--------------------------------
-
- For many machines, multiple types of branch instructions are
-provided, each for different length branch displacements. In most
-cases, the assembler will choose the correct instruction to use.
-However, when the assembler cannot do so, GCC can when a special
-attribute, the `length' attribute, is defined. This attribute must be
-defined to have numeric values by specifying a null string in its
-`define_attr'.
-
- In the case of the `length' attribute, two additional forms of
-arithmetic terms are allowed in test expressions:
-
-`(match_dup N)'
- This refers to the address of operand N of the current insn, which
- must be a `label_ref'.
-
-`(pc)'
- This refers to the address of the _current_ insn. It might have
- been more consistent with other usage to make this the address of
- the _next_ insn but this would be confusing because the length of
- the current insn is to be computed.
-
- For normal insns, the length will be determined by value of the
-`length' attribute. In the case of `addr_vec' and `addr_diff_vec' insn
-patterns, the length is computed as the number of vectors multiplied by
-the size of each vector.
-
- Lengths are measured in addressable storage units (bytes).
-
- The following macros can be used to refine the length computation:
-
-`FIRST_INSN_ADDRESS'
- When the `length' insn attribute is used, this macro specifies the
- value to be assigned to the address of the first insn in a
- function. If not specified, 0 is used.
-
-`ADJUST_INSN_LENGTH (INSN, LENGTH)'
- If defined, modifies the length assigned to instruction INSN as a
- function of the context in which it is used. LENGTH is an lvalue
- that contains the initially computed length of the insn and should
- be updated with the correct length of the insn.
-
- This macro will normally not be required. A case in which it is
- required is the ROMP. On this machine, the size of an `addr_vec'
- insn must be increased by two to compensate for the fact that
- alignment may be required.
-
- The routine that returns `get_attr_length' (the value of the
-`length' attribute) can be used by the output routine to determine the
-form of the branch instruction to be written, as the example below
-illustrates.
-
- As an example of the specification of variable-length branches,
-consider the IBM 360. If we adopt the convention that a register will
-be set to the starting address of a function, we can jump to labels
-within 4k of the start using a four-byte instruction. Otherwise, we
-need a six-byte sequence to load the address from memory and then
-branch to it.
-
- On such a machine, a pattern for a branch instruction might be
-specified as follows:
-
- (define_insn "jump"
- [(set (pc)
- (label_ref (match_operand 0 "" "")))]
- ""
- {
- return (get_attr_length (insn) == 4
- ? "b %l0" : "l r15,=a(%l0); br r15");
- }
- [(set (attr "length")
- (if_then_else (lt (match_dup 0) (const_int 4096))
- (const_int 4)
- (const_int 6)))])
-
-\1f
-File: gccint.info, Node: Constant Attributes, Next: Delay Slots, Prev: Insn Lengths, Up: Insn Attributes
-
-Constant Attributes
--------------------
-
- A special form of `define_attr', where the expression for the
-default value is a `const' expression, indicates an attribute that is
-constant for a given run of the compiler. Constant attributes may be
-used to specify which variety of processor is used. For example,
-
- (define_attr "cpu" "m88100,m88110,m88000"
- (const
- (cond [(symbol_ref "TARGET_88100") (const_string "m88100")
- (symbol_ref "TARGET_88110") (const_string "m88110")]
- (const_string "m88000"))))
-
- (define_attr "memory" "fast,slow"
- (const
- (if_then_else (symbol_ref "TARGET_FAST_MEM")
- (const_string "fast")
- (const_string "slow"))))
-
- The routine generated for constant attributes has no parameters as it
-does not depend on any particular insn. RTL expressions used to define
-the value of a constant attribute may use the `symbol_ref' form, but
-may not use either the `match_operand' form or `eq_attr' forms
-involving insn attributes.
-
-\1f
-File: gccint.info, Node: Delay Slots, Next: Function Units, Prev: Constant Attributes, Up: Insn Attributes
-
-Delay Slot Scheduling
----------------------
-
- The insn attribute mechanism can be used to specify the requirements
-for delay slots, if any, on a target machine. An instruction is said to
-require a "delay slot" if some instructions that are physically after
-the instruction are executed as if they were located before it.
-Classic examples are branch and call instructions, which often execute
-the following instruction before the branch or call is performed.
-
- On some machines, conditional branch instructions can optionally
-"annul" instructions in the delay slot. This means that the
-instruction will not be executed for certain branch outcomes. Both
-instructions that annul if the branch is true and instructions that
-annul if the branch is false are supported.
-
- Delay slot scheduling differs from instruction scheduling in that
-determining whether an instruction needs a delay slot is dependent only
-on the type of instruction being generated, not on data flow between the
-instructions. See the next section for a discussion of data-dependent
-instruction scheduling.
-
- The requirement of an insn needing one or more delay slots is
-indicated via the `define_delay' expression. It has the following form:
-
- (define_delay TEST
- [DELAY-1 ANNUL-TRUE-1 ANNUL-FALSE-1
- DELAY-2 ANNUL-TRUE-2 ANNUL-FALSE-2
- ...])
-
- TEST is an attribute test that indicates whether this `define_delay'
-applies to a particular insn. If so, the number of required delay
-slots is determined by the length of the vector specified as the second
-argument. An insn placed in delay slot N must satisfy attribute test
-DELAY-N. ANNUL-TRUE-N is an attribute test that specifies which insns
-may be annulled if the branch is true. Similarly, ANNUL-FALSE-N
-specifies which insns in the delay slot may be annulled if the branch
-is false. If annulling is not supported for that delay slot, `(nil)'
-should be coded.
-
- For example, in the common case where branch and call insns require
-a single delay slot, which may contain any insn other than a branch or
-call, the following would be placed in the `md' file:
-
- (define_delay (eq_attr "type" "branch,call")
- [(eq_attr "type" "!branch,call") (nil) (nil)])
-
- Multiple `define_delay' expressions may be specified. In this case,
-each such expression specifies different delay slot requirements and
-there must be no insn for which tests in two `define_delay' expressions
-are both true.
-
- For example, if we have a machine that requires one delay slot for
-branches but two for calls, no delay slot can contain a branch or call
-insn, and any valid insn in the delay slot for the branch can be
-annulled if the branch is true, we might represent this as follows:
-
- (define_delay (eq_attr "type" "branch")
- [(eq_attr "type" "!branch,call")
- (eq_attr "type" "!branch,call")
- (nil)])
-
- (define_delay (eq_attr "type" "call")
- [(eq_attr "type" "!branch,call") (nil) (nil)
- (eq_attr "type" "!branch,call") (nil) (nil)])
-
-\1f
-File: gccint.info, Node: Function Units, Prev: Delay Slots, Up: Insn Attributes
-
-Specifying Function Units
--------------------------
-
- On most RISC machines, there are instructions whose results are not
-available for a specific number of cycles. Common cases are
-instructions that load data from memory. On many machines, a pipeline
-stall will result if the data is referenced too soon after the load
-instruction.
-
- In addition, many newer microprocessors have multiple function
-units, usually one for integer and one for floating point, and often
-will incur pipeline stalls when a result that is needed is not yet
-ready.
-
- The descriptions in this section allow the specification of how much
-time must elapse between the execution of an instruction and the time
-when its result is used. It also allows specification of when the
-execution of an instruction will delay execution of similar instructions
-due to function unit conflicts.
-
- For the purposes of the specifications in this section, a machine is
-divided into "function units", each of which execute a specific class
-of instructions in first-in-first-out order. Function units that
-accept one instruction each cycle and allow a result to be used in the
-succeeding instruction (usually via forwarding) need not be specified.
-Classic RISC microprocessors will normally have a single function unit,
-which we can call `memory'. The newer "superscalar" processors will
-often have function units for floating point operations, usually at
-least a floating point adder and multiplier.
-
- Each usage of a function units by a class of insns is specified with
-a `define_function_unit' expression, which looks like this:
-
- (define_function_unit NAME MULTIPLICITY SIMULTANEITY
- TEST READY-DELAY ISSUE-DELAY
- [CONFLICT-LIST])
-
- NAME is a string giving the name of the function unit.
-
- MULTIPLICITY is an integer specifying the number of identical units
-in the processor. If more than one unit is specified, they will be
-scheduled independently. Only truly independent units should be
-counted; a pipelined unit should be specified as a single unit. (The
-only common example of a machine that has multiple function units for a
-single instruction class that are truly independent and not pipelined
-are the two multiply and two increment units of the CDC 6600.)
-
- SIMULTANEITY specifies the maximum number of insns that can be
-executing in each instance of the function unit simultaneously or zero
-if the unit is pipelined and has no limit.
-
- All `define_function_unit' definitions referring to function unit
-NAME must have the same name and values for MULTIPLICITY and
-SIMULTANEITY.
-
- TEST is an attribute test that selects the insns we are describing
-in this definition. Note that an insn may use more than one function
-unit and a function unit may be specified in more than one
-`define_function_unit'.
-
- READY-DELAY is an integer that specifies the number of cycles after
-which the result of the instruction can be used without introducing any
-stalls.
-
- ISSUE-DELAY is an integer that specifies the number of cycles after
-the instruction matching the TEST expression begins using this unit
-until a subsequent instruction can begin. A cost of N indicates an N-1
-cycle delay. A subsequent instruction may also be delayed if an
-earlier instruction has a longer READY-DELAY value. This blocking
-effect is computed using the SIMULTANEITY, READY-DELAY, ISSUE-DELAY,
-and CONFLICT-LIST terms. For a normal non-pipelined function unit,
-SIMULTANEITY is one, the unit is taken to block for the READY-DELAY
-cycles of the executing insn, and smaller values of ISSUE-DELAY are
-ignored.
-
- CONFLICT-LIST is an optional list giving detailed conflict costs for
-this unit. If specified, it is a list of condition test expressions to
-be applied to insns chosen to execute in NAME following the particular
-insn matching TEST that is already executing in NAME. For each insn in
-the list, ISSUE-DELAY specifies the conflict cost; for insns not in the
-list, the cost is zero. If not specified, CONFLICT-LIST defaults to
-all instructions that use the function unit.
-
- Typical uses of this vector are where a floating point function unit
-can pipeline either single- or double-precision operations, but not
-both, or where a memory unit can pipeline loads, but not stores, etc.
-
- As an example, consider a classic RISC machine where the result of a
-load instruction is not available for two cycles (a single "delay"
-instruction is required) and where only one load instruction can be
-executed simultaneously. This would be specified as:
-
- (define_function_unit "memory" 1 1 (eq_attr "type" "load") 2 0)
-
- For the case of a floating point function unit that can pipeline
-either single or double precision, but not both, the following could be
-specified:
-
- (define_function_unit
- "fp" 1 0 (eq_attr "type" "sp_fp") 4 4 [(eq_attr "type" "dp_fp")])
- (define_function_unit
- "fp" 1 0 (eq_attr "type" "dp_fp") 4 4 [(eq_attr "type" "sp_fp")])
-
- *Note:* The scheduler attempts to avoid function unit conflicts and
-uses all the specifications in the `define_function_unit' expression.
-It has recently come to our attention that these specifications may not
-allow modeling of some of the newer "superscalar" processors that have
-insns using multiple pipelined units. These insns will cause a
-potential conflict for the second unit used during their execution and
-there is no way of representing that conflict. We welcome any examples
-of how function unit conflicts work in such processors and suggestions
-for their representation.
-
-\1f
-File: gccint.info, Node: Conditional Execution, Next: Constant Definitions, Prev: Insn Attributes, Up: Machine Desc
-
-Conditional Execution
-=====================
-
- A number of architectures provide for some form of conditional
-execution, or predication. The hallmark of this feature is the ability
-to nullify most of the instructions in the instruction set. When the
-instruction set is large and not entirely symmetric, it can be quite
-tedious to describe these forms directly in the `.md' file. An
-alternative is the `define_cond_exec' template.
-
- (define_cond_exec
- [PREDICATE-PATTERN]
- "CONDITION"
- "OUTPUT-TEMPLATE")
-
- PREDICATE-PATTERN is the condition that must be true for the insn to
-be executed at runtime and should match a relational operator. One can
-use `match_operator' to match several relational operators at once.
-Any `match_operand' operands must have no more than one alternative.
-
- CONDITION is a C expression that must be true for the generated
-pattern to match.
-
- OUTPUT-TEMPLATE is a string similar to the `define_insn' output
-template (*note Output Template::), except that the `*' and `@' special
-cases do not apply. This is only useful if the assembly text for the
-predicate is a simple prefix to the main insn. In order to handle the
-general case, there is a global variable `current_insn_predicate' that
-will contain the entire predicate if the current insn is predicated,
-and will otherwise be `NULL'.
-
- When `define_cond_exec' is used, an implicit reference to the
-`predicable' instruction attribute is made. *Note Insn Attributes::.
-This attribute must be boolean (i.e. have exactly two elements in its
-LIST-OF-VALUES). Further, it must not be used with complex
-expressions. That is, the default and all uses in the insns must be a
-simple constant, not dependent on the alternative or anything else.
-
- For each `define_insn' for which the `predicable' attribute is true,
-a new `define_insn' pattern will be generated that matches a predicated
-version of the instruction. For example,
-
- (define_insn "addsi"
- [(set (match_operand:SI 0 "register_operand" "r")
- (plus:SI (match_operand:SI 1 "register_operand" "r")
- (match_operand:SI 2 "register_operand" "r")))]
- "TEST1"
- "add %2,%1,%0")
-
- (define_cond_exec
- [(ne (match_operand:CC 0 "register_operand" "c")
- (const_int 0))]
- "TEST2"
- "(%0)")
-
-generates a new pattern
-
- (define_insn ""
- [(cond_exec
- (ne (match_operand:CC 3 "register_operand" "c") (const_int 0))
- (set (match_operand:SI 0 "register_operand" "r")
- (plus:SI (match_operand:SI 1 "register_operand" "r")
- (match_operand:SI 2 "register_operand" "r"))))]
- "(TEST2) && (TEST1)"
- "(%3) add %2,%1,%0")
-
-\1f
-File: gccint.info, Node: Constant Definitions, Prev: Conditional Execution, Up: Machine Desc
-
-Constant Definitions
-====================
-
- Using literal constants inside instruction patterns reduces
-legibility and can be a maintenance problem.
-
- To overcome this problem, you may use the `define_constants'
-expression. It contains a vector of name-value pairs. From that point
-on, wherever any of the names appears in the MD file, it is as if the
-corresponding value had been written instead. You may use
-`define_constants' multiple times; each appearance adds more constants
-to the table. It is an error to redefine a constant with a different
-value.
-
- To come back to the a29k load multiple example, instead of
-
- (define_insn ""
- [(match_parallel 0 "load_multiple_operation"
- [(set (match_operand:SI 1 "gpc_reg_operand" "=r")
- (match_operand:SI 2 "memory_operand" "m"))
- (use (reg:SI 179))
- (clobber (reg:SI 179))])]
- ""
- "loadm 0,0,%1,%2")
-
- You could write:
-
- (define_constants [
- (R_BP 177)
- (R_FC 178)
- (R_CR 179)
- (R_Q 180)
- ])
-
- (define_insn ""
- [(match_parallel 0 "load_multiple_operation"
- [(set (match_operand:SI 1 "gpc_reg_operand" "=r")
- (match_operand:SI 2 "memory_operand" "m"))
- (use (reg:SI R_CR))
- (clobber (reg:SI R_CR))])]
- ""
- "loadm 0,0,%1,%2")
-
- The constants that are defined with a define_constant are also output
-in the insn-codes.h header file as #defines.
-
-\1f
-File: gccint.info, Node: Target Macros, Next: Host Config, Prev: Machine Desc, Up: Top
-
-Target Description Macros and Functions
-***************************************
-
- In addition to the file `MACHINE.md', a machine description includes
-a C header file conventionally given the name `MACHINE.h' and a C
-source file named `MACHINE.c'. The header file defines numerous macros
-that convey the information about the target machine that does not fit
-into the scheme of the `.md' file. The file `tm.h' should be a link to
-`MACHINE.h'. The header file `config.h' includes `tm.h' and most
-compiler source files include `config.h'. The source file defines a
-variable `targetm', which is a structure containing pointers to
-functions and data relating to the target machine. `MACHINE.c' should
-also contain their definitions, if they are not defined elsewhere in
-GCC, and other functions called through the macros defined in the `.h'
-file.
-
-* Menu:
-
-* Target Structure:: The `targetm' variable.
-* Driver:: Controlling how the driver runs the compilation passes.
-* Run-time Target:: Defining `-m' options like `-m68000' and `-m68020'.
-* Per-Function Data:: Defining data structures for per-function information.
-* Storage Layout:: Defining sizes and alignments of data.
-* Type Layout:: Defining sizes and properties of basic user data types.
-* Escape Sequences:: Defining the value of target character escape sequences
-* Registers:: Naming and describing the hardware registers.
-* Register Classes:: Defining the classes of hardware registers.
-* Stack and Calling:: Defining which way the stack grows and by how much.
-* Varargs:: Defining the varargs macros.
-* Trampolines:: Code set up at run time to enter a nested function.
-* Library Calls:: Controlling how library routines are implicitly called.
-* Addressing Modes:: Defining addressing modes valid for memory operands.
-* Condition Code:: Defining how insns update the condition code.
-* Costs:: Defining relative costs of different operations.
-* Scheduling:: Adjusting the behavior of the instruction scheduler.
-* Sections:: Dividing storage into text, data, and other sections.
-* PIC:: Macros for position independent code.
-* Assembler Format:: Defining how to write insns and pseudo-ops to output.
-* Debugging Info:: Defining the format of debugging output.
-* Cross-compilation:: Handling floating point for cross-compilers.
-* Mode Switching:: Insertion of mode-switching instructions.
-* Target Attributes:: Defining target-specific uses of `__attribute__'.
-* Misc:: Everything else.
-
-\1f
-File: gccint.info, Node: Target Structure, Next: Driver, Up: Target Macros
-
-The Global `targetm' Variable
-=============================
-
- - Variable: struct gcc_target targetm
- The target `.c' file must define the global `targetm' variable
- which contains pointers to functions and data relating to the
- target machine. The variable is declared in `target.h';
- `target-def.h' defines the macro `TARGET_INITIALIZER' which is
- used to initialize the variable, and macros for the default
- initializers for elements of the structure. The `.c' file should
- override those macros for which the default definition is
- inappropriate. For example:
- #include "target.h"
- #include "target-def.h"
-
- /* Initialize the GCC target structure. */
-
- #undef TARGET_COMP_TYPE_ATTRIBUTES
- #define TARGET_COMP_TYPE_ATTRIBUTES MACHINE_comp_type_attributes
-
- struct gcc_target targetm = TARGET_INITIALIZER;
-
- Where a macro should be defined in the `.c' file in this manner to
-form part of the `targetm' structure, it is documented below as a
-"Target Hook" with a prototype. Many macros will change in future from
-being defined in the `.h' file to being part of the `targetm' structure.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Driver, Next: Run-time Target, Prev: Target Structure, Up: Target Macros
-
-Controlling the Compilation Driver, `gcc'
-=========================================
-
- You can control the compilation driver.
-
-`SWITCH_TAKES_ARG (CHAR)'
- A C expression which determines whether the option `-CHAR' takes
- arguments. The value should be the number of arguments that
- option takes-zero, for many options.
-
- By default, this macro is defined as `DEFAULT_SWITCH_TAKES_ARG',
- which handles the standard options properly. You need not define
- `SWITCH_TAKES_ARG' unless you wish to add additional options which
- take arguments. Any redefinition should call
- `DEFAULT_SWITCH_TAKES_ARG' and then check for additional options.
-
-`WORD_SWITCH_TAKES_ARG (NAME)'
- A C expression which determines whether the option `-NAME' takes
- arguments. The value should be the number of arguments that
- option takes-zero, for many options. This macro rather than
- `SWITCH_TAKES_ARG' is used for multi-character option names.
-
- By default, this macro is defined as
- `DEFAULT_WORD_SWITCH_TAKES_ARG', which handles the standard options
- properly. You need not define `WORD_SWITCH_TAKES_ARG' unless you
- wish to add additional options which take arguments. Any
- redefinition should call `DEFAULT_WORD_SWITCH_TAKES_ARG' and then
- check for additional options.
-
-`SWITCH_CURTAILS_COMPILATION (CHAR)'
- A C expression which determines whether the option `-CHAR' stops
- compilation before the generation of an executable. The value is
- boolean, nonzero if the option does stop an executable from being
- generated, zero otherwise.
-
- By default, this macro is defined as
- `DEFAULT_SWITCH_CURTAILS_COMPILATION', which handles the standard
- options properly. You need not define
- `SWITCH_CURTAILS_COMPILATION' unless you wish to add additional
- options which affect the generation of an executable. Any
- redefinition should call `DEFAULT_SWITCH_CURTAILS_COMPILATION' and
- then check for additional options.
-
-`SWITCHES_NEED_SPACES'
- A string-valued C expression which enumerates the options for which
- the linker needs a space between the option and its argument.
-
- If this macro is not defined, the default value is `""'.
-
-`TARGET_OPTION_TRANSLATE_TABLE'
- If defined, a list of pairs of strings, the first of which is a
- potential command line target to the `gcc' driver program, and the
- second of which is a space-separated (tabs and other whitespace
- are not supported) list of options with which to replace the first
- option. The target defining this list is responsible for assuring
- that the results are valid. Replacement options may not be the
- `--opt' style, they must be the `-opt' style. It is the intention
- of this macro to provide a mechanism for substitution that affects
- the multilibs chosen, such as one option that enables many
- options, some of which select multilibs. Example nonsensical
- definition, where `-malt-abi', `-EB', and `-mspoo' cause different
- multilibs to be chosen:
-
- #define TARGET_OPTION_TRANSLATE_TABLE \
- { "-fast", "-march=fast-foo -malt-abi -I/usr/fast-foo" }, \
- { "-compat", "-EB -malign=4 -mspoo" }
-
-`CPP_SPEC'
- A C string constant that tells the GCC driver program options to
- pass to CPP. It can also specify how to translate options you
- give to GCC into options for GCC to pass to the CPP.
-
- Do not define this macro if it does not need to do anything.
-
-`CPLUSPLUS_CPP_SPEC'
- This macro is just like `CPP_SPEC', but is used for C++, rather
- than C. If you do not define this macro, then the value of
- `CPP_SPEC' (if any) will be used instead.
-
-`NO_BUILTIN_SIZE_TYPE'
- If this macro is defined, the preprocessor will not define the
- built-in macro `__SIZE_TYPE__'. The macro `__SIZE_TYPE__' must
- then be defined by `CPP_SPEC' instead.
-
- This should be defined if `SIZE_TYPE' depends on target dependent
- flags which are not accessible to the preprocessor. Otherwise, it
- should not be defined.
-
-`NO_BUILTIN_PTRDIFF_TYPE'
- If this macro is defined, the preprocessor will not define the
- built-in macro `__PTRDIFF_TYPE__'. The macro `__PTRDIFF_TYPE__'
- must then be defined by `CPP_SPEC' instead.
-
- This should be defined if `PTRDIFF_TYPE' depends on target
- dependent flags which are not accessible to the preprocessor.
- Otherwise, it should not be defined.
-
-`NO_BUILTIN_WCHAR_TYPE'
- If this macro is defined, the preprocessor will not define the
- built-in macro `__WCHAR_TYPE__'. The macro `__WCHAR_TYPE__' must
- then be defined by `CPP_SPEC' instead.
-
- This should be defined if `WCHAR_TYPE' depends on target dependent
- flags which are not accessible to the preprocessor. Otherwise, it
- should not be defined.
-
-`NO_BUILTIN_WINT_TYPE'
- If this macro is defined, the preprocessor will not define the
- built-in macro `__WINT_TYPE__'. The macro `__WINT_TYPE__' must
- then be defined by `CPP_SPEC' instead.
-
- This should be defined if `WINT_TYPE' depends on target dependent
- flags which are not accessible to the preprocessor. Otherwise, it
- should not be defined.
-
-`CC1_SPEC'
- A C string constant that tells the GCC driver program options to
- pass to `cc1', `cc1plus', `f771', and the other language front
- ends. It can also specify how to translate options you give to
- GCC into options for GCC to pass to front ends.
-
- Do not define this macro if it does not need to do anything.
-
-`CC1PLUS_SPEC'
- A C string constant that tells the GCC driver program options to
- pass to `cc1plus'. It can also specify how to translate options
- you give to GCC into options for GCC to pass to the `cc1plus'.
-
- Do not define this macro if it does not need to do anything. Note
- that everything defined in CC1_SPEC is already passed to `cc1plus'
- so there is no need to duplicate the contents of CC1_SPEC in
- CC1PLUS_SPEC.
-
-`ASM_SPEC'
- A C string constant that tells the GCC driver program options to
- pass to the assembler. It can also specify how to translate
- options you give to GCC into options for GCC to pass to the
- assembler. See the file `sun3.h' for an example of this.
-
- Do not define this macro if it does not need to do anything.
-
-`ASM_FINAL_SPEC'
- A C string constant that tells the GCC driver program how to run
- any programs which cleanup after the normal assembler. Normally,
- this is not needed. See the file `mips.h' for an example of this.
-
- Do not define this macro if it does not need to do anything.
-
-`LINK_SPEC'
- A C string constant that tells the GCC driver program options to
- pass to the linker. It can also specify how to translate options
- you give to GCC into options for GCC to pass to the linker.
-
- Do not define this macro if it does not need to do anything.
-
-`LIB_SPEC'
- Another C string constant used much like `LINK_SPEC'. The
- difference between the two is that `LIB_SPEC' is used at the end
- of the command given to the linker.
-
- If this macro is not defined, a default is provided that loads the
- standard C library from the usual place. See `gcc.c'.
-
-`LIBGCC_SPEC'
- Another C string constant that tells the GCC driver program how
- and when to place a reference to `libgcc.a' into the linker
- command line. This constant is placed both before and after the
- value of `LIB_SPEC'.
-
- If this macro is not defined, the GCC driver provides a default
- that passes the string `-lgcc' to the linker.
-
-`STARTFILE_SPEC'
- Another C string constant used much like `LINK_SPEC'. The
- difference between the two is that `STARTFILE_SPEC' is used at the
- very beginning of the command given to the linker.
-
- If this macro is not defined, a default is provided that loads the
- standard C startup file from the usual place. See `gcc.c'.
-
-`ENDFILE_SPEC'
- Another C string constant used much like `LINK_SPEC'. The
- difference between the two is that `ENDFILE_SPEC' is used at the
- very end of the command given to the linker.
-
- Do not define this macro if it does not need to do anything.
-
-`THREAD_MODEL_SPEC'
- GCC `-v' will print the thread model GCC was configured to use.
- However, this doesn't work on platforms that are multilibbed on
- thread models, such as AIX 4.3. On such platforms, define
- `THREAD_MODEL_SPEC' such that it evaluates to a string without
- blanks that names one of the recognized thread models. `%*', the
- default value of this macro, will expand to the value of
- `thread_file' set in `config.gcc'.
-
-`EXTRA_SPECS'
- Define this macro to provide additional specifications to put in
- the `specs' file that can be used in various specifications like
- `CC1_SPEC'.
-
- The definition should be an initializer for an array of structures,
- containing a string constant, that defines the specification name,
- and a string constant that provides the specification.
-
- Do not define this macro if it does not need to do anything.
-
- `EXTRA_SPECS' is useful when an architecture contains several
- related targets, which have various `..._SPECS' which are similar
- to each other, and the maintainer would like one central place to
- keep these definitions.
-
- For example, the PowerPC System V.4 targets use `EXTRA_SPECS' to
- define either `_CALL_SYSV' when the System V calling sequence is
- used or `_CALL_AIX' when the older AIX-based calling sequence is
- used.
-
- The `config/rs6000/rs6000.h' target file defines:
-
- #define EXTRA_SPECS \
- { "cpp_sysv_default", CPP_SYSV_DEFAULT },
-
- #define CPP_SYS_DEFAULT ""
-
- The `config/rs6000/sysv.h' target file defines:
- #undef CPP_SPEC
- #define CPP_SPEC \
- "%{posix: -D_POSIX_SOURCE } \
- %{mcall-sysv: -D_CALL_SYSV } %{mcall-aix: -D_CALL_AIX } \
- %{!mcall-sysv: %{!mcall-aix: %(cpp_sysv_default) }} \
- %{msoft-float: -D_SOFT_FLOAT} %{mcpu=403: -D_SOFT_FLOAT}"
-
- #undef CPP_SYSV_DEFAULT
- #define CPP_SYSV_DEFAULT "-D_CALL_SYSV"
-
- while the `config/rs6000/eabiaix.h' target file defines
- `CPP_SYSV_DEFAULT' as:
-
- #undef CPP_SYSV_DEFAULT
- #define CPP_SYSV_DEFAULT "-D_CALL_AIX"
-
-`LINK_LIBGCC_SPECIAL'
- Define this macro if the driver program should find the library
- `libgcc.a' itself and should not pass `-L' options to the linker.
- If you do not define this macro, the driver program will pass the
- argument `-lgcc' to tell the linker to do the search and will pass
- `-L' options to it.
-
-`LINK_LIBGCC_SPECIAL_1'
- Define this macro if the driver program should find the library
- `libgcc.a'. If you do not define this macro, the driver program
- will pass the argument `-lgcc' to tell the linker to do the search.
- This macro is similar to `LINK_LIBGCC_SPECIAL', except that it does
- not affect `-L' options.
-
-`LINK_GCC_C_SEQUENCE_SPEC'
- The sequence in which libgcc and libc are specified to the linker.
- By default this is `%G %L %G'.
-
-`LINK_COMMAND_SPEC'
- A C string constant giving the complete command line need to
- execute the linker. When you do this, you will need to update
- your port each time a change is made to the link command line
- within `gcc.c'. Therefore, define this macro only if you need to
- completely redefine the command line for invoking the linker and
- there is no other way to accomplish the effect you need.
- Overriding this macro may be avoidable by overriding
- `LINK_GCC_C_SEQUENCE_SPEC' instead.
-
-`LINK_ELIMINATE_DUPLICATE_LDIRECTORIES'
- A nonzero value causes `collect2' to remove duplicate
- `-LDIRECTORY' search directories from linking commands. Do not
- give it a nonzero value if removing duplicate search directories
- changes the linker's semantics.
-
-`MULTILIB_DEFAULTS'
- Define this macro as a C expression for the initializer of an
- array of string to tell the driver program which options are
- defaults for this target and thus do not need to be handled
- specially when using `MULTILIB_OPTIONS'.
-
- Do not define this macro if `MULTILIB_OPTIONS' is not defined in
- the target makefile fragment or if none of the options listed in
- `MULTILIB_OPTIONS' are set by default. *Note Target Fragment::.
-
-`RELATIVE_PREFIX_NOT_LINKDIR'
- Define this macro to tell `gcc' that it should only translate a
- `-B' prefix into a `-L' linker option if the prefix indicates an
- absolute file name.
-
-`STANDARD_EXEC_PREFIX'
- Define this macro as a C string constant if you wish to override
- the standard choice of `/usr/local/lib/gcc-lib/' as the default
- prefix to try when searching for the executable files of the
- compiler.
-
-`MD_EXEC_PREFIX'
- If defined, this macro is an additional prefix to try after
- `STANDARD_EXEC_PREFIX'. `MD_EXEC_PREFIX' is not searched when the
- `-b' option is used, or the compiler is built as a cross compiler.
- If you define `MD_EXEC_PREFIX', then be sure to add it to the
- list of directories used to find the assembler in `configure.in'.
-
-`STANDARD_STARTFILE_PREFIX'
- Define this macro as a C string constant if you wish to override
- the standard choice of `/usr/local/lib/' as the default prefix to
- try when searching for startup files such as `crt0.o'.
-
-`MD_STARTFILE_PREFIX'
- If defined, this macro supplies an additional prefix to try after
- the standard prefixes. `MD_EXEC_PREFIX' is not searched when the
- `-b' option is used, or when the compiler is built as a cross
- compiler.
-
-`MD_STARTFILE_PREFIX_1'
- If defined, this macro supplies yet another prefix to try after the
- standard prefixes. It is not searched when the `-b' option is
- used, or when the compiler is built as a cross compiler.
-
-`INIT_ENVIRONMENT'
- Define this macro as a C string constant if you wish to set
- environment variables for programs called by the driver, such as
- the assembler and loader. The driver passes the value of this
- macro to `putenv' to initialize the necessary environment
- variables.
-
-`LOCAL_INCLUDE_DIR'
- Define this macro as a C string constant if you wish to override
- the standard choice of `/usr/local/include' as the default prefix
- to try when searching for local header files. `LOCAL_INCLUDE_DIR'
- comes before `SYSTEM_INCLUDE_DIR' in the search order.
-
- Cross compilers do not search either `/usr/local/include' or its
- replacement.
-
-`MODIFY_TARGET_NAME'
- Define this macro if you with to define command-line switches that
- modify the default target name
-
- For each switch, you can include a string to be appended to the
- first part of the configuration name or a string to be deleted
- from the configuration name, if present. The definition should be
- an initializer for an array of structures. Each array element
- should have three elements: the switch name (a string constant,
- including the initial dash), one of the enumeration codes `ADD' or
- `DELETE' to indicate whether the string should be inserted or
- deleted, and the string to be inserted or deleted (a string
- constant).
-
- For example, on a machine where `64' at the end of the
- configuration name denotes a 64-bit target and you want the `-32'
- and `-64' switches to select between 32- and 64-bit targets, you
- would code
-
- #define MODIFY_TARGET_NAME \
- { { "-32", DELETE, "64"}, \
- {"-64", ADD, "64"}}
-
-`SYSTEM_INCLUDE_DIR'
- Define this macro as a C string constant if you wish to specify a
- system-specific directory to search for header files before the
- standard directory. `SYSTEM_INCLUDE_DIR' comes before
- `STANDARD_INCLUDE_DIR' in the search order.
-
- Cross compilers do not use this macro and do not search the
- directory specified.
-
-`STANDARD_INCLUDE_DIR'
- Define this macro as a C string constant if you wish to override
- the standard choice of `/usr/include' as the default prefix to try
- when searching for header files.
-
- Cross compilers do not use this macro and do not search either
- `/usr/include' or its replacement.
-
-`STANDARD_INCLUDE_COMPONENT'
- The "component" corresponding to `STANDARD_INCLUDE_DIR'. See
- `INCLUDE_DEFAULTS', below, for the description of components. If
- you do not define this macro, no component is used.
-
-`INCLUDE_DEFAULTS'
- Define this macro if you wish to override the entire default
- search path for include files. For a native compiler, the default
- search path usually consists of `GCC_INCLUDE_DIR',
- `LOCAL_INCLUDE_DIR', `SYSTEM_INCLUDE_DIR',
- `GPLUSPLUS_INCLUDE_DIR', and `STANDARD_INCLUDE_DIR'. In addition,
- `GPLUSPLUS_INCLUDE_DIR' and `GCC_INCLUDE_DIR' are defined
- automatically by `Makefile', and specify private search areas for
- GCC. The directory `GPLUSPLUS_INCLUDE_DIR' is used only for C++
- programs.
-
- The definition should be an initializer for an array of structures.
- Each array element should have four elements: the directory name (a
- string constant), the component name (also a string constant), a
- flag for C++-only directories, and a flag showing that the
- includes in the directory don't need to be wrapped in `extern `C''
- when compiling C++. Mark the end of the array with a null element.
-
- The component name denotes what GNU package the include file is
- part of, if any, in all upper-case letters. For example, it might
- be `GCC' or `BINUTILS'. If the package is part of a
- vendor-supplied operating system, code the component name as `0'.
-
- For example, here is the definition used for VAX/VMS:
-
- #define INCLUDE_DEFAULTS \
- { \
- { "GNU_GXX_INCLUDE:", "G++", 1, 1}, \
- { "GNU_CC_INCLUDE:", "GCC", 0, 0}, \
- { "SYS$SYSROOT:[SYSLIB.]", 0, 0, 0}, \
- { ".", 0, 0, 0}, \
- { 0, 0, 0, 0} \
- }
-
- Here is the order of prefixes tried for exec files:
-
- 1. Any prefixes specified by the user with `-B'.
-
- 2. The environment variable `GCC_EXEC_PREFIX', if any.
-
- 3. The directories specified by the environment variable
- `COMPILER_PATH'.
-
- 4. The macro `STANDARD_EXEC_PREFIX'.
-
- 5. `/usr/lib/gcc/'.
-
- 6. The macro `MD_EXEC_PREFIX', if any.
-
- Here is the order of prefixes tried for startfiles:
-
- 1. Any prefixes specified by the user with `-B'.
-
- 2. The environment variable `GCC_EXEC_PREFIX', if any.
-
- 3. The directories specified by the environment variable
- `LIBRARY_PATH' (or port-specific name; native only, cross
- compilers do not use this).
-
- 4. The macro `STANDARD_EXEC_PREFIX'.
-
- 5. `/usr/lib/gcc/'.
-
- 6. The macro `MD_EXEC_PREFIX', if any.
-
- 7. The macro `MD_STARTFILE_PREFIX', if any.
-
- 8. The macro `STANDARD_STARTFILE_PREFIX'.
-
- 9. `/lib/'.
-
- 10. `/usr/lib/'.
-
-\1f
-File: gccint.info, Node: Run-time Target, Next: Per-Function Data, Prev: Driver, Up: Target Macros
-
-Run-time Target Specification
-=============================
-
- Here are run-time target specifications.
-
-`CPP_PREDEFINES'
- Define this to be a string constant containing `-D' options to
- define the predefined macros that identify this machine and system.
- These macros will be predefined unless the `-ansi' option (or a
- `-std' option for strict ISO C conformance) is specified.
-
- In addition, a parallel set of macros are predefined, whose names
- are made by appending `__' at the beginning and at the end. These
- `__' macros are permitted by the ISO standard, so they are
- predefined regardless of whether `-ansi' or a `-std' option is
- specified.
-
- For example, on the Sun, one can use the following value:
-
- "-Dmc68000 -Dsun -Dunix"
-
- The result is to define the macros `__mc68000__', `__sun__' and
- `__unix__' unconditionally, and the macros `mc68000', `sun' and
- `unix' provided `-ansi' is not specified.
-
-`extern int target_flags;'
- This declaration should be present.
-
-`TARGET_...'
- This series of macros is to allow compiler command arguments to
- enable or disable the use of optional features of the target
- machine. For example, one machine description serves both the
- 68000 and the 68020; a command argument tells the compiler whether
- it should use 68020-only instructions or not. This command
- argument works by means of a macro `TARGET_68020' that tests a bit
- in `target_flags'.
-
- Define a macro `TARGET_FEATURENAME' for each such option. Its
- definition should test a bit in `target_flags'. It is recommended
- that a helper macro `TARGET_MASK_FEATURENAME' is defined for each
- bit-value to test, and used in `TARGET_FEATURENAME' and
- `TARGET_SWITCHES'. For example:
-
- #define TARGET_MASK_68020 1
- #define TARGET_68020 (target_flags & TARGET_MASK_68020)
-
- One place where these macros are used is in the
- condition-expressions of instruction patterns. Note how
- `TARGET_68020' appears frequently in the 68000 machine description
- file, `m68k.md'. Another place they are used is in the
- definitions of the other macros in the `MACHINE.h' file.
-
-`TARGET_SWITCHES'
- This macro defines names of command options to set and clear bits
- in `target_flags'. Its definition is an initializer with a
- subgrouping for each command option.
-
- Each subgrouping contains a string constant, that defines the
- option name, a number, which contains the bits to set in
- `target_flags', and a second string which is the description
- displayed by `--help'. If the number is negative then the bits
- specified by the number are cleared instead of being set. If the
- description string is present but empty, then no help information
- will be displayed for that option, but it will not count as an
- undocumented option. The actual option name is made by appending
- `-m' to the specified name. Non-empty description strings should
- be marked with `N_(...)' for `xgettext'. Please do not mark empty
- strings because the empty string is reserved by GNU gettext.
- `gettext("")' returns the header entry of the message catalog with
- meta information, not the empty string.
-
- In addition to the description for `--help', more detailed
- documentation for each option should be added to `invoke.texi'.
-
- One of the subgroupings should have a null string. The number in
- this grouping is the default value for `target_flags'. Any target
- options act starting with that value.
-
- Here is an example which defines `-m68000' and `-m68020' with
- opposite meanings, and picks the latter as the default:
-
- #define TARGET_SWITCHES \
- { { "68020", TARGET_MASK_68020, "" }, \
- { "68000", -TARGET_MASK_68020, \
- N_("Compile for the 68000") }, \
- { "", TARGET_MASK_68020, "" }}
-
-`TARGET_OPTIONS'
- This macro is similar to `TARGET_SWITCHES' but defines names of
- command options that have values. Its definition is an
- initializer with a subgrouping for each command option.
-
- Each subgrouping contains a string constant, that defines the
- fixed part of the option name, the address of a variable, and a
- description string. Non-empty description strings should be
- marked with `N_(...)' for `xgettext'. Please do not mark empty
- strings because the empty string is reserved by GNU gettext.
- `gettext("")' returns the header entry of the message catalog with
- meta information, not the empty string.
-
- The variable, type `char *', is set to the variable part of the
- given option if the fixed part matches. The actual option name is
- made by appending `-m' to the specified name. Again, each option
- should also be documented in `invoke.texi'.
-
- Here is an example which defines `-mshort-data-NUMBER'. If the
- given option is `-mshort-data-512', the variable `m88k_short_data'
- will be set to the string `"512"'.
-
- extern char *m88k_short_data;
- #define TARGET_OPTIONS \
- { { "short-data-", &m88k_short_data, \
- N_("Specify the size of the short data section") } }
-
-`TARGET_VERSION'
- This macro is a C statement to print on `stderr' a string
- describing the particular machine description choice. Every
- machine description should define `TARGET_VERSION'. For example:
-
- #ifdef MOTOROLA
- #define TARGET_VERSION \
- fprintf (stderr, " (68k, Motorola syntax)");
- #else
- #define TARGET_VERSION \
- fprintf (stderr, " (68k, MIT syntax)");
- #endif
-
-`OVERRIDE_OPTIONS'
- Sometimes certain combinations of command options do not make
- sense on a particular target machine. You can define a macro
- `OVERRIDE_OPTIONS' to take account of this. This macro, if
- defined, is executed once just after all the command options have
- been parsed.
-
- Don't use this macro to turn on various extra optimizations for
- `-O'. That is what `OPTIMIZATION_OPTIONS' is for.
-
-`OPTIMIZATION_OPTIONS (LEVEL, SIZE)'
- Some machines may desire to change what optimizations are
- performed for various optimization levels. This macro, if
- defined, is executed once just after the optimization level is
- determined and before the remainder of the command options have
- been parsed. Values set in this macro are used as the default
- values for the other command line options.
-
- LEVEL is the optimization level specified; 2 if `-O2' is
- specified, 1 if `-O' is specified, and 0 if neither is specified.
-
- SIZE is nonzero if `-Os' is specified and zero otherwise.
-
- You should not use this macro to change options that are not
- machine-specific. These should uniformly selected by the same
- optimization level on all supported machines. Use this macro to
- enable machine-specific optimizations.
-
- *Do not examine `write_symbols' in this macro!* The debugging
- options are not supposed to alter the generated code.
-
-`CAN_DEBUG_WITHOUT_FP'
- Define this macro if debugging can be performed even without a
- frame pointer. If this macro is defined, GCC will turn on the
- `-fomit-frame-pointer' option whenever `-O' is specified.
-
-\1f
-File: gccint.info, Node: Per-Function Data, Next: Storage Layout, Prev: Run-time Target, Up: Target Macros
-
-Defining data structures for per-function information.
-======================================================
-
- If the target needs to store information on a per-function basis, GCC
-provides a macro and a couple of variables to allow this. Note, just
-using statics to store the information is a bad idea, since GCC supports
-nested functions, so you can be halfway through encoding one function
-when another one comes along.
-
- GCC defines a data structure called `struct function' which contains
-all of the data specific to an individual function. This structure
-contains a field called `machine' whose type is `struct
-machine_function *', which can be used by targets to point to their own
-specific data.
-
- If a target needs per-function specific data it should define the
-type `struct machine_function' and also the macro `INIT_EXPANDERS'.
-This macro should be used to initialize some or all of the function
-pointers `init_machine_status', `free_machine_status' and
-`mark_machine_status'. These pointers are explained below.
-
- One typical use of per-function, target specific data is to create an
-RTX to hold the register containing the function's return address. This
-RTX can then be used to implement the `__builtin_return_address'
-function, for level 0.
-
- Note--earlier implementations of GCC used a single data area to hold
-all of the per-function information. Thus when processing of a nested
-function began the old per-function data had to be pushed onto a stack,
-and when the processing was finished, it had to be popped off the
-stack. GCC used to provide function pointers called
-`save_machine_status' and `restore_machine_status' to handle the saving
-and restoring of the target specific information. Since the single
-data area approach is no longer used, these pointers are no longer
-supported.
-
- The macro and function pointers are described below.
-
-`INIT_EXPANDERS'
- Macro called to initialize any target specific information. This
- macro is called once per function, before generation of any RTL
- has begun. The intention of this macro is to allow the
- initialization of the function pointers below.
-
-`init_machine_status'
- This is a `void (*)(struct function *)' function pointer. If this
- pointer is non-`NULL' it will be called once per function, before
- function compilation starts, in order to allow the target to
- perform any target specific initialization of the `struct
- function' structure. It is intended that this would be used to
- initialize the `machine' of that structure.
-
-`free_machine_status'
- This is a `void (*)(struct function *)' function pointer. If this
- pointer is non-`NULL' it will be called once per function, after
- the function has been compiled, in order to allow any memory
- allocated during the `init_machine_status' function call to be
- freed.
-
-`mark_machine_status'
- This is a `void (*)(struct function *)' function pointer. If this
- pointer is non-`NULL' it will be called once per function in order
- to mark any data items in the `struct machine_function' structure
- which need garbage collection.
-
-
-\1f
-File: gccint.info, Node: Storage Layout, Next: Type Layout, Prev: Per-Function Data, Up: Target Macros
-
-Storage Layout
-==============
-
- Note that the definitions of the macros in this table which are
-sizes or alignments measured in bits do not need to be constant. They
-can be C expressions that refer to static variables, such as the
-`target_flags'. *Note Run-time Target::.
-
-`BITS_BIG_ENDIAN'
- Define this macro to have the value 1 if the most significant bit
- in a byte has the lowest number; otherwise define it to have the
- value zero. This means that bit-field instructions count from the
- most significant bit. If the machine has no bit-field
- instructions, then this must still be defined, but it doesn't
- matter which value it is defined to. This macro need not be a
- constant.
-
- This macro does not affect the way structure fields are packed into
- bytes or words; that is controlled by `BYTES_BIG_ENDIAN'.
-
-`BYTES_BIG_ENDIAN'
- Define this macro to have the value 1 if the most significant byte
- in a word has the lowest number. This macro need not be a
- constant.
-
-`WORDS_BIG_ENDIAN'
- Define this macro to have the value 1 if, in a multiword object,
- the most significant word has the lowest number. This applies to
- both memory locations and registers; GCC fundamentally assumes
- that the order of words in memory is the same as the order in
- registers. This macro need not be a constant.
-
-`LIBGCC2_WORDS_BIG_ENDIAN'
- Define this macro if `WORDS_BIG_ENDIAN' is not constant. This
- must be a constant value with the same meaning as
- `WORDS_BIG_ENDIAN', which will be used only when compiling
- `libgcc2.c'. Typically the value will be set based on
- preprocessor defines.
-
-`FLOAT_WORDS_BIG_ENDIAN'
- Define this macro to have the value 1 if `DFmode', `XFmode' or
- `TFmode' floating point numbers are stored in memory with the word
- containing the sign bit at the lowest address; otherwise define it
- to have the value 0. This macro need not be a constant.
-
- You need not define this macro if the ordering is the same as for
- multi-word integers.
-
-`BITS_PER_UNIT'
- Define this macro to be the number of bits in an addressable
- storage unit (byte); normally 8.
-
-`BITS_PER_WORD'
- Number of bits in a word; normally 32.
-
-`MAX_BITS_PER_WORD'
- Maximum number of bits in a word. If this is undefined, the
- default is `BITS_PER_WORD'. Otherwise, it is the constant value
- that is the largest value that `BITS_PER_WORD' can have at
- run-time.
-
-`UNITS_PER_WORD'
- Number of storage units in a word; normally 4.
-
-`MIN_UNITS_PER_WORD'
- Minimum number of units in a word. If this is undefined, the
- default is `UNITS_PER_WORD'. Otherwise, it is the constant value
- that is the smallest value that `UNITS_PER_WORD' can have at
- run-time.
-
-`POINTER_SIZE'
- Width of a pointer, in bits. You must specify a value no wider
- than the width of `Pmode'. If it is not equal to the width of
- `Pmode', you must define `POINTERS_EXTEND_UNSIGNED'.
-
-`POINTERS_EXTEND_UNSIGNED'
- A C expression whose value is greater than zero if pointers that
- need to be extended from being `POINTER_SIZE' bits wide to `Pmode'
- are to be zero-extended and zero if they are to be sign-extended.
- If the value is less then zero then there must be an "ptr_extend"
- instruction that extends a pointer from `POINTER_SIZE' to `Pmode'.
-
- You need not define this macro if the `POINTER_SIZE' is equal to
- the width of `Pmode'.
-
-`PROMOTE_MODE (M, UNSIGNEDP, TYPE)'
- A macro to update M and UNSIGNEDP when an object whose type is
- TYPE and which has the specified mode and signedness is to be
- stored in a register. This macro is only called when TYPE is a
- scalar type.
-
- On most RISC machines, which only have operations that operate on
- a full register, define this macro to set M to `word_mode' if M is
- an integer mode narrower than `BITS_PER_WORD'. In most cases,
- only integer modes should be widened because wider-precision
- floating-point operations are usually more expensive than their
- narrower counterparts.
-
- For most machines, the macro definition does not change UNSIGNEDP.
- However, some machines, have instructions that preferentially
- handle either signed or unsigned quantities of certain modes. For
- example, on the DEC Alpha, 32-bit loads from memory and 32-bit add
- instructions sign-extend the result to 64 bits. On such machines,
- set UNSIGNEDP according to which kind of extension is more
- efficient.
-
- Do not define this macro if it would never modify M.
-
-`PROMOTE_FUNCTION_ARGS'
- Define this macro if the promotion described by `PROMOTE_MODE'
- should also be done for outgoing function arguments.
-
-`PROMOTE_FUNCTION_RETURN'
- Define this macro if the promotion described by `PROMOTE_MODE'
- should also be done for the return value of functions.
-
- If this macro is defined, `FUNCTION_VALUE' must perform the same
- promotions done by `PROMOTE_MODE'.
-
-`PROMOTE_FOR_CALL_ONLY'
- Define this macro if the promotion described by `PROMOTE_MODE'
- should _only_ be performed for outgoing function arguments or
- function return values, as specified by `PROMOTE_FUNCTION_ARGS'
- and `PROMOTE_FUNCTION_RETURN', respectively.
-
-`PARM_BOUNDARY'
- Normal alignment required for function parameters on the stack, in
- bits. All stack parameters receive at least this much alignment
- regardless of data type. On most machines, this is the same as the
- size of an integer.
-
-`STACK_BOUNDARY'
- Define this macro to the minimum alignment enforced by hardware
- for the stack pointer on this machine. The definition is a C
- expression for the desired alignment (measured in bits). This
- value is used as a default if `PREFERRED_STACK_BOUNDARY' is not
- defined. On most machines, this should be the same as
- `PARM_BOUNDARY'.
-
-`PREFERRED_STACK_BOUNDARY'
- Define this macro if you wish to preserve a certain alignment for
- the stack pointer, greater than what the hardware enforces. The
- definition is a C expression for the desired alignment (measured
- in bits). This macro must evaluate to a value equal to or larger
- than `STACK_BOUNDARY'.
-
-`FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN'
- A C expression that evaluates true if `PREFERRED_STACK_BOUNDARY' is
- not guaranteed by the runtime and we should emit code to align the
- stack at the beginning of `main'.
-
- If `PUSH_ROUNDING' is not defined, the stack will always be aligned
- to the specified boundary. If `PUSH_ROUNDING' is defined and
- specifies a less strict alignment than `PREFERRED_STACK_BOUNDARY',
- the stack may be momentarily unaligned while pushing arguments.
-
-`FUNCTION_BOUNDARY'
- Alignment required for a function entry point, in bits.
-
-`BIGGEST_ALIGNMENT'
- Biggest alignment that any data type can require on this machine,
- in bits.
-
-`MINIMUM_ATOMIC_ALIGNMENT'
- If defined, the smallest alignment, in bits, that can be given to
- an object that can be referenced in one operation, without
- disturbing any nearby object. Normally, this is `BITS_PER_UNIT',
- but may be larger on machines that don't have byte or half-word
- store operations.
-
-`BIGGEST_FIELD_ALIGNMENT'
- Biggest alignment that any structure or union field can require on
- this machine, in bits. If defined, this overrides
- `BIGGEST_ALIGNMENT' for structure and union fields only, unless
- the field alignment has been set by the `__attribute__ ((aligned
- (N)))' construct.
-
-`ADJUST_FIELD_ALIGN (FIELD, COMPUTED)'
- An expression for the alignment of a structure field FIELD if the
- alignment computed in the usual way (including applying of
- `BIGGEST_ALIGNMENT' and `BIGGEST_FIELD_ALIGNMENT' to the
- alignment) is COMPUTED. It overrides alignment only if the field
- alignment has not been set by the `__attribute__ ((aligned (N)))'
- construct.
-
-`MAX_OFILE_ALIGNMENT'
- Biggest alignment supported by the object file format of this
- machine. Use this macro to limit the alignment which can be
- specified using the `__attribute__ ((aligned (N)))' construct. If
- not defined, the default value is `BIGGEST_ALIGNMENT'.
-
-`DATA_ALIGNMENT (TYPE, BASIC-ALIGN)'
- If defined, a C expression to compute the alignment for a variable
- in the static store. TYPE is the data type, and BASIC-ALIGN is
- the alignment that the object would ordinarily have. The value of
- this macro is used instead of that alignment to align the object.
-
- If this macro is not defined, then BASIC-ALIGN is used.
-
- One use of this macro is to increase alignment of medium-size data
- to make it all fit in fewer cache lines. Another is to cause
- character arrays to be word-aligned so that `strcpy' calls that
- copy constants to character arrays can be done inline.
-
-`CONSTANT_ALIGNMENT (CONSTANT, BASIC-ALIGN)'
- If defined, a C expression to compute the alignment given to a
- constant that is being placed in memory. CONSTANT is the constant
- and BASIC-ALIGN is the alignment that the object would ordinarily
- have. The value of this macro is used instead of that alignment to
- align the object.
-
- If this macro is not defined, then BASIC-ALIGN is used.
-
- The typical use of this macro is to increase alignment for string
- constants to be word aligned so that `strcpy' calls that copy
- constants can be done inline.
-
-`LOCAL_ALIGNMENT (TYPE, BASIC-ALIGN)'
- If defined, a C expression to compute the alignment for a variable
- in the local store. TYPE is the data type, and BASIC-ALIGN is the
- alignment that the object would ordinarily have. The value of this
- macro is used instead of that alignment to align the object.
-
- If this macro is not defined, then BASIC-ALIGN is used.
-
- One use of this macro is to increase alignment of medium-size data
- to make it all fit in fewer cache lines.
-
-`EMPTY_FIELD_BOUNDARY'
- Alignment in bits to be given to a structure bit-field that
- follows an empty field such as `int : 0;'.
-
- Note that `PCC_BITFIELD_TYPE_MATTERS' also affects the alignment
- that results from an empty field.
-
-`STRUCTURE_SIZE_BOUNDARY'
- Number of bits which any structure or union's size must be a
- multiple of. Each structure or union's size is rounded up to a
- multiple of this.
-
- If you do not define this macro, the default is the same as
- `BITS_PER_UNIT'.
-
-`STRICT_ALIGNMENT'
- Define this macro to be the value 1 if instructions will fail to
- work if given data not on the nominal alignment. If instructions
- will merely go slower in that case, define this macro as 0.
-
-`PCC_BITFIELD_TYPE_MATTERS'
- Define this if you wish to imitate the way many other C compilers
- handle alignment of bit-fields and the structures that contain
- them.
-
- The behavior is that the type written for a bit-field (`int',
- `short', or other integer type) imposes an alignment for the
- entire structure, as if the structure really did contain an
- ordinary field of that type. In addition, the bit-field is placed
- within the structure so that it would fit within such a field, not
- crossing a boundary for it.
-
- Thus, on most machines, a bit-field whose type is written as `int'
- would not cross a four-byte boundary, and would force four-byte
- alignment for the whole structure. (The alignment used may not be
- four bytes; it is controlled by the other alignment parameters.)
-
- If the macro is defined, its definition should be a C expression;
- a nonzero value for the expression enables this behavior.
-
- Note that if this macro is not defined, or its value is zero, some
- bit-fields may cross more than one alignment boundary. The
- compiler can support such references if there are `insv', `extv',
- and `extzv' insns that can directly reference memory.
-
- The other known way of making bit-fields work is to define
- `STRUCTURE_SIZE_BOUNDARY' as large as `BIGGEST_ALIGNMENT'. Then
- every structure can be accessed with fullwords.
-
- Unless the machine has bit-field instructions or you define
- `STRUCTURE_SIZE_BOUNDARY' that way, you must define
- `PCC_BITFIELD_TYPE_MATTERS' to have a nonzero value.
-
- If your aim is to make GCC use the same conventions for laying out
- bit-fields as are used by another compiler, here is how to
- investigate what the other compiler does. Compile and run this
- program:
-
- struct foo1
- {
- char x;
- char :0;
- char y;
- };
-
- struct foo2
- {
- char x;
- int :0;
- char y;
- };
-
- main ()
- {
- printf ("Size of foo1 is %d\n",
- sizeof (struct foo1));
- printf ("Size of foo2 is %d\n",
- sizeof (struct foo2));
- exit (0);
- }
-
- If this prints 2 and 5, then the compiler's behavior is what you
- would get from `PCC_BITFIELD_TYPE_MATTERS'.
-
-`BITFIELD_NBYTES_LIMITED'
- Like `PCC_BITFIELD_TYPE_MATTERS' except that its effect is limited
- to aligning a bit-field within the structure.
-
-`MEMBER_TYPE_FORCES_BLK (FIELD)'
- Return 1 if a structure or array containing FIELD should be
- accessed using `BLKMODE'.
-
- Normally, this is not needed. See the file `c4x.h' for an example
- of how to use this macro to prevent a structure having a floating
- point field from being accessed in an integer mode.
-
-`ROUND_TYPE_SIZE (TYPE, COMPUTED, SPECIFIED)'
- Define this macro as an expression for the overall size of a type
- (given by TYPE as a tree node) when the size computed in the usual
- way is COMPUTED and the alignment is SPECIFIED.
-
- The default is to round COMPUTED up to a multiple of SPECIFIED.
-
-`ROUND_TYPE_SIZE_UNIT (TYPE, COMPUTED, SPECIFIED)'
- Similar to `ROUND_TYPE_SIZE', but sizes and alignments are
- specified in units (bytes). If you define `ROUND_TYPE_SIZE', you
- must also define this macro and they must be defined consistently
- with each other.
-
-`ROUND_TYPE_ALIGN (TYPE, COMPUTED, SPECIFIED)'
- Define this macro as an expression for the alignment of a type
- (given by TYPE as a tree node) if the alignment computed in the
- usual way is COMPUTED and the alignment explicitly specified was
- SPECIFIED.
-
- The default is to use SPECIFIED if it is larger; otherwise, use
- the smaller of COMPUTED and `BIGGEST_ALIGNMENT'
-
-`MAX_FIXED_MODE_SIZE'
- An integer expression for the size in bits of the largest integer
- machine mode that should actually be used. All integer machine
- modes of this size or smaller can be used for structures and
- unions with the appropriate sizes. If this macro is undefined,
- `GET_MODE_BITSIZE (DImode)' is assumed.
-
-`VECTOR_MODE_SUPPORTED_P(MODE)'
- Define this macro to be nonzero if the port is prepared to handle
- insns involving vector mode MODE. At the very least, it must have
- move patterns for this mode.
-
-`STACK_SAVEAREA_MODE (SAVE_LEVEL)'
- If defined, an expression of type `enum machine_mode' that
- specifies the mode of the save area operand of a
- `save_stack_LEVEL' named pattern (*note Standard Names::).
- SAVE_LEVEL is one of `SAVE_BLOCK', `SAVE_FUNCTION', or
- `SAVE_NONLOCAL' and selects which of the three named patterns is
- having its mode specified.
-
- You need not define this macro if it always returns `Pmode'. You
- would most commonly define this macro if the `save_stack_LEVEL'
- patterns need to support both a 32- and a 64-bit mode.
-
-`STACK_SIZE_MODE'
- If defined, an expression of type `enum machine_mode' that
- specifies the mode of the size increment operand of an
- `allocate_stack' named pattern (*note Standard Names::).
-
- You need not define this macro if it always returns `word_mode'.
- You would most commonly define this macro if the `allocate_stack'
- pattern needs to support both a 32- and a 64-bit mode.
-
-`CHECK_FLOAT_VALUE (MODE, VALUE, OVERFLOW)'
- A C statement to validate the value VALUE (of type `double') for
- mode MODE. This means that you check whether VALUE fits within
- the possible range of values for mode MODE on this target machine.
- The mode MODE is always a mode of class `MODE_FLOAT'. OVERFLOW
- is nonzero if the value is already known to be out of range.
-
- If VALUE is not valid or if OVERFLOW is nonzero, you should set
- OVERFLOW to 1 and then assign some valid value to VALUE. Allowing
- an invalid value to go through the compiler can produce incorrect
- assembler code which may even cause Unix assemblers to crash.
-
- This macro need not be defined if there is no work for it to do.
-
-`TARGET_FLOAT_FORMAT'
- A code distinguishing the floating point format of the target
- machine. There are five defined values:
-
- `IEEE_FLOAT_FORMAT'
- This code indicates IEEE floating point. It is the default;
- there is no need to define this macro when the format is IEEE.
-
- `VAX_FLOAT_FORMAT'
- This code indicates the "D float" format used on the VAX.
-
- `IBM_FLOAT_FORMAT'
- This code indicates the format used on the IBM System/370.
-
- `C4X_FLOAT_FORMAT'
- This code indicates the format used on the TMS320C3x/C4x.
-
- `UNKNOWN_FLOAT_FORMAT'
- This code indicates any other format.
-
- The value of this macro is compared with `HOST_FLOAT_FORMAT', which
- is defined by the `configure' script, to determine whether the
- target machine has the same format as the host machine. If any
- other formats are actually in use on supported machines, new codes
- should be defined for them.
-
- The ordering of the component words of floating point values
- stored in memory is controlled by `FLOAT_WORDS_BIG_ENDIAN'.
-
-
- - Target Hook: bool TARGET_MS_BITFIELD_LAYOUT_P (tree RECORD_TYPE)
- This target hook returns `true' if bit-fields in the given
- RECORD_TYPE are to be laid out following the rules of Microsoft
- Visual C/C++, namely: (i) a bit-field won't share the same storage
- unit with the previous bit-field if their underlying types have
- different sizes, and the bit-field will be aligned to the highest
- alignment of the underlying types of itself and of the previous
- bit-field; (ii) a zero-sized bit-field will affect the alignment of
- the whole enclosing structure, even if it is unnamed; except that
- (iii) a zero-sized bit-field will be disregarded unless it follows
- another bit-field of non-zero size. If this hook returns `true',
- other macros that control bit-field layout are ignored.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Type Layout, Next: Escape Sequences, Prev: Storage Layout, Up: Target Macros
-
-Layout of Source Language Data Types
-====================================
-
- These macros define the sizes and other characteristics of the
-standard basic data types used in programs being compiled. Unlike the
-macros in the previous section, these apply to specific features of C
-and related languages, rather than to fundamental aspects of storage
-layout.
-
-`INT_TYPE_SIZE'
- A C expression for the size in bits of the type `int' on the
- target machine. If you don't define this, the default is one word.
-
-`SHORT_TYPE_SIZE'
- A C expression for the size in bits of the type `short' on the
- target machine. If you don't define this, the default is half a
- word. (If this would be less than one storage unit, it is rounded
- up to one unit.)
-
-`LONG_TYPE_SIZE'
- A C expression for the size in bits of the type `long' on the
- target machine. If you don't define this, the default is one word.
-
-`ADA_LONG_TYPE_SIZE'
- On some machines, the size used for the Ada equivalent of the type
- `long' by a native Ada compiler differs from that used by C. In
- that situation, define this macro to be a C expression to be used
- for the size of that type. If you don't define this, the default
- is the value of `LONG_TYPE_SIZE'.
-
-`MAX_LONG_TYPE_SIZE'
- Maximum number for the size in bits of the type `long' on the
- target machine. If this is undefined, the default is
- `LONG_TYPE_SIZE'. Otherwise, it is the constant value that is the
- largest value that `LONG_TYPE_SIZE' can have at run-time. This is
- used in `cpp'.
-
-`LONG_LONG_TYPE_SIZE'
- A C expression for the size in bits of the type `long long' on the
- target machine. If you don't define this, the default is two
- words. If you want to support GNU Ada on your machine, the value
- of this macro must be at least 64.
-
-`CHAR_TYPE_SIZE'
- A C expression for the size in bits of the type `char' on the
- target machine. If you don't define this, the default is
- `BITS_PER_UNIT'.
-
-`MAX_CHAR_TYPE_SIZE'
- Maximum number for the size in bits of the type `char' on the
- target machine. If this is undefined, the default is
- `CHAR_TYPE_SIZE'. Otherwise, it is the constant value that is the
- largest value that `CHAR_TYPE_SIZE' can have at run-time. This is
- used in `cpp'.
-
-`BOOL_TYPE_SIZE'
- A C expression for the size in bits of the C++ type `bool' and C99
- type `_Bool' on the target machine. If you don't define this, and
- you probably shouldn't, the default is `CHAR_TYPE_SIZE'.
-
-`FLOAT_TYPE_SIZE'
- A C expression for the size in bits of the type `float' on the
- target machine. If you don't define this, the default is one word.
-
-`DOUBLE_TYPE_SIZE'
- A C expression for the size in bits of the type `double' on the
- target machine. If you don't define this, the default is two
- words.
-
-`LONG_DOUBLE_TYPE_SIZE'
- A C expression for the size in bits of the type `long double' on
- the target machine. If you don't define this, the default is two
- words.
-
- Maximum number for the size in bits of the type `long double' on
- the target machine. If this is undefined, the default is
- `LONG_DOUBLE_TYPE_SIZE'. Otherwise, it is the constant value that
- is the largest value that `LONG_DOUBLE_TYPE_SIZE' can have at
- run-time. This is used in `cpp'.
-
- Define this macro to be 1 if the target machine uses 80-bit
- floating-point values with 128-bit size and alignment. This is
- used in `real.c'.
-
-`WIDEST_HARDWARE_FP_SIZE'
- A C expression for the size in bits of the widest floating-point
- format supported by the hardware. If you define this macro, you
- must specify a value less than or equal to the value of
- `LONG_DOUBLE_TYPE_SIZE'. If you do not define this macro, the
- value of `LONG_DOUBLE_TYPE_SIZE' is the default.
-
-`DEFAULT_SIGNED_CHAR'
- An expression whose value is 1 or 0, according to whether the type
- `char' should be signed or unsigned by default. The user can
- always override this default with the options `-fsigned-char' and
- `-funsigned-char'.
-
-`DEFAULT_SHORT_ENUMS'
- A C expression to determine whether to give an `enum' type only as
- many bytes as it takes to represent the range of possible values
- of that type. A nonzero value means to do that; a zero value
- means all `enum' types should be allocated like `int'.
-
- If you don't define the macro, the default is 0.
-
-`SIZE_TYPE'
- A C expression for a string describing the name of the data type
- to use for size values. The typedef name `size_t' is defined
- using the contents of the string.
-
- The string can contain more than one keyword. If so, separate
- them with spaces, and write first any length keyword, then
- `unsigned' if appropriate, and finally `int'. The string must
- exactly match one of the data type names defined in the function
- `init_decl_processing' in the file `c-decl.c'. You may not omit
- `int' or change the order--that would cause the compiler to crash
- on startup.
-
- If you don't define this macro, the default is `"long unsigned
- int"'.
-
-`PTRDIFF_TYPE'
- A C expression for a string describing the name of the data type
- to use for the result of subtracting two pointers. The typedef
- name `ptrdiff_t' is defined using the contents of the string. See
- `SIZE_TYPE' above for more information.
-
- If you don't define this macro, the default is `"long int"'.
-
-`WCHAR_TYPE'
- A C expression for a string describing the name of the data type
- to use for wide characters. The typedef name `wchar_t' is defined
- using the contents of the string. See `SIZE_TYPE' above for more
- information.
-
- If you don't define this macro, the default is `"int"'.
-
-`WCHAR_TYPE_SIZE'
- A C expression for the size in bits of the data type for wide
- characters. This is used in `cpp', which cannot make use of
- `WCHAR_TYPE'.
-
-`MAX_WCHAR_TYPE_SIZE'
- Maximum number for the size in bits of the data type for wide
- characters. If this is undefined, the default is
- `WCHAR_TYPE_SIZE'. Otherwise, it is the constant value that is the
- largest value that `WCHAR_TYPE_SIZE' can have at run-time. This is
- used in `cpp'.
-
-`GCOV_TYPE_SIZE'
- A C expression for the size in bits of the type used for gcov
- counters on the target machine. If you don't define this, the
- default is one `LONG_TYPE_SIZE' in case it is greater or equal to
- 64-bit and `LONG_LONG_TYPE_SIZE' otherwise. You may want to
- re-define the type to ensure atomicity for counters in
- multithreaded programs.
-
-`WINT_TYPE'
- A C expression for a string describing the name of the data type to
- use for wide characters passed to `printf' and returned from
- `getwc'. The typedef name `wint_t' is defined using the contents
- of the string. See `SIZE_TYPE' above for more information.
-
- If you don't define this macro, the default is `"unsigned int"'.
-
-`INTMAX_TYPE'
- A C expression for a string describing the name of the data type
- that can represent any value of any standard or extended signed
- integer type. The typedef name `intmax_t' is defined using the
- contents of the string. See `SIZE_TYPE' above for more
- information.
-
- If you don't define this macro, the default is the first of
- `"int"', `"long int"', or `"long long int"' that has as much
- precision as `long long int'.
-
-`UINTMAX_TYPE'
- A C expression for a string describing the name of the data type
- that can represent any value of any standard or extended unsigned
- integer type. The typedef name `uintmax_t' is defined using the
- contents of the string. See `SIZE_TYPE' above for more
- information.
-
- If you don't define this macro, the default is the first of
- `"unsigned int"', `"long unsigned int"', or `"long long unsigned
- int"' that has as much precision as `long long unsigned int'.
-
-`TARGET_PTRMEMFUNC_VBIT_LOCATION'
- The C++ compiler represents a pointer-to-member-function with a
- struct that looks like:
-
- struct {
- union {
- void (*fn)();
- ptrdiff_t vtable_index;
- };
- ptrdiff_t delta;
- };
-
- The C++ compiler must use one bit to indicate whether the function
- that will be called through a pointer-to-member-function is
- virtual. Normally, we assume that the low-order bit of a function
- pointer must always be zero. Then, by ensuring that the
- vtable_index is odd, we can distinguish which variant of the union
- is in use. But, on some platforms function pointers can be odd,
- and so this doesn't work. In that case, we use the low-order bit
- of the `delta' field, and shift the remainder of the `delta' field
- to the left.
-
- GCC will automatically make the right selection about where to
- store this bit using the `FUNCTION_BOUNDARY' setting for your
- platform. However, some platforms such as ARM/Thumb have
- `FUNCTION_BOUNDARY' set such that functions always start at even
- addresses, but the lowest bit of pointers to functions indicate
- whether the function at that address is in ARM or Thumb mode. If
- this is the case of your architecture, you should define this
- macro to `ptrmemfunc_vbit_in_delta'.
-
- In general, you should not have to define this macro. On
- architectures in which function addresses are always even,
- according to `FUNCTION_BOUNDARY', GCC will automatically define
- this macro to `ptrmemfunc_vbit_in_pfn'.
-
-`TARGET_VTABLE_USES_DESCRIPTORS'
- Normally, the C++ compiler uses function pointers in vtables. This
- macro allows the target to change to use "function descriptors"
- instead. Function descriptors are found on targets for whom a
- function pointer is actually a small data structure. Normally the
- data structure consists of the actual code address plus a data
- pointer to which the function's data is relative.
-
- If vtables are used, the value of this macro should be the number
- of words that the function descriptor occupies.
-
-\1f
-File: gccint.info, Node: Escape Sequences, Next: Registers, Prev: Type Layout, Up: Target Macros
-
-Target Character Escape Sequences
-=================================
-
- By default, GCC assumes that the C character escape sequences take on
-their ASCII values for the target. If this is not correct, you must
-explicitly define all of the macros below.
-
-`TARGET_BELL'
- A C constant expression for the integer value for escape sequence
- `\a'.
-
-`TARGET_ESC'
- A C constant expression for the integer value of the target escape
- character. As an extension, GCC evaluates the escape sequences
- `\e' and `\E' to this.
-
-`TARGET_BS'
-`TARGET_TAB'
-`TARGET_NEWLINE'
- C constant expressions for the integer values for escape sequences
- `\b', `\t' and `\n'.
-
-`TARGET_VT'
-`TARGET_FF'
-`TARGET_CR'
- C constant expressions for the integer values for escape sequences
- `\v', `\f' and `\r'.
-
-\1f
-File: gccint.info, Node: Registers, Next: Register Classes, Prev: Escape Sequences, Up: Target Macros
-
-Register Usage
-==============
-
- This section explains how to describe what registers the target
-machine has, and how (in general) they can be used.
-
- The description of which registers a specific instruction can use is
-done with register classes; see *Note Register Classes::. For
-information on using registers to access a stack frame, see *Note Frame
-Registers::. For passing values in registers, see *Note Register
-Arguments::. For returning values in registers, see *Note Scalar
-Return::.
-
-* Menu:
-
-* Register Basics:: Number and kinds of registers.
-* Allocation Order:: Order in which registers are allocated.
-* Values in Registers:: What kinds of values each reg can hold.
-* Leaf Functions:: Renumbering registers for leaf functions.
-* Stack Registers:: Handling a register stack such as 80387.
-
-\1f
-File: gccint.info, Node: Register Basics, Next: Allocation Order, Up: Registers
-
-Basic Characteristics of Registers
-----------------------------------
-
- Registers have various characteristics.
-
-`FIRST_PSEUDO_REGISTER'
- Number of hardware registers known to the compiler. They receive
- numbers 0 through `FIRST_PSEUDO_REGISTER-1'; thus, the first
- pseudo register's number really is assigned the number
- `FIRST_PSEUDO_REGISTER'.
-
-`FIXED_REGISTERS'
- An initializer that says which registers are used for fixed
- purposes all throughout the compiled code and are therefore not
- available for general allocation. These would include the stack
- pointer, the frame pointer (except on machines where that can be
- used as a general register when no frame pointer is needed), the
- program counter on machines where that is considered one of the
- addressable registers, and any other numbered register with a
- standard use.
-
- This information is expressed as a sequence of numbers, separated
- by commas and surrounded by braces. The Nth number is 1 if
- register N is fixed, 0 otherwise.
-
- The table initialized from this macro, and the table initialized by
- the following one, may be overridden at run time either
- automatically, by the actions of the macro
- `CONDITIONAL_REGISTER_USAGE', or by the user with the command
- options `-ffixed-REG', `-fcall-used-REG' and `-fcall-saved-REG'.
-
-`CALL_USED_REGISTERS'
- Like `FIXED_REGISTERS' but has 1 for each register that is
- clobbered (in general) by function calls as well as for fixed
- registers. This macro therefore identifies the registers that are
- not available for general allocation of values that must live
- across function calls.
-
- If a register has 0 in `CALL_USED_REGISTERS', the compiler
- automatically saves it on function entry and restores it on
- function exit, if the register is used within the function.
-
-`CALL_REALLY_USED_REGISTERS'
- Like `CALL_USED_REGISTERS' except this macro doesn't require that
- the entire set of `FIXED_REGISTERS' be included.
- (`CALL_USED_REGISTERS' must be a superset of `FIXED_REGISTERS').
- This macro is optional. If not specified, it defaults to the value
- of `CALL_USED_REGISTERS'.
-
-`HARD_REGNO_CALL_PART_CLOBBERED (REGNO, MODE)'
- A C expression that is nonzero if it is not permissible to store a
- value of mode MODE in hard register number REGNO across a call
- without some part of it being clobbered. For most machines this
- macro need not be defined. It is only required for machines that
- do not preserve the entire contents of a register across a call.
-
-`CONDITIONAL_REGISTER_USAGE'
- Zero or more C statements that may conditionally modify five
- variables `fixed_regs', `call_used_regs', `global_regs',
- `reg_names', and `reg_class_contents', to take into account any
- dependence of these register sets on target flags. The first three
- of these are of type `char []' (interpreted as Boolean vectors).
- `global_regs' is a `const char *[]', and `reg_class_contents' is a
- `HARD_REG_SET'. Before the macro is called, `fixed_regs',
- `call_used_regs', `reg_class_contents', and `reg_names' have been
- initialized from `FIXED_REGISTERS', `CALL_USED_REGISTERS',
- `REG_CLASS_CONTENTS', and `REGISTER_NAMES', respectively.
- `global_regs' has been cleared, and any `-ffixed-REG',
- `-fcall-used-REG' and `-fcall-saved-REG' command options have been
- applied.
-
- You need not define this macro if it has no work to do.
-
- If the usage of an entire class of registers depends on the target
- flags, you may indicate this to GCC by using this macro to modify
- `fixed_regs' and `call_used_regs' to 1 for each of the registers
- in the classes which should not be used by GCC. Also define the
- macro `REG_CLASS_FROM_LETTER' to return `NO_REGS' if it is called
- with a letter for a class that shouldn't be used.
-
- (However, if this class is not included in `GENERAL_REGS' and all
- of the insn patterns whose constraints permit this class are
- controlled by target switches, then GCC will automatically avoid
- using these registers when the target switches are opposed to
- them.)
-
-`NON_SAVING_SETJMP'
- If this macro is defined and has a nonzero value, it means that
- `setjmp' and related functions fail to save the registers, or that
- `longjmp' fails to restore them. To compensate, the compiler
- avoids putting variables in registers in functions that use
- `setjmp'.
-
-`INCOMING_REGNO (OUT)'
- Define this macro if the target machine has register windows.
- This C expression returns the register number as seen by the
- called function corresponding to the register number OUT as seen
- by the calling function. Return OUT if register number OUT is not
- an outbound register.
-
-`OUTGOING_REGNO (IN)'
- Define this macro if the target machine has register windows.
- This C expression returns the register number as seen by the
- calling function corresponding to the register number IN as seen
- by the called function. Return IN if register number IN is not an
- inbound register.
-
-`LOCAL_REGNO (REGNO)'
- Define this macro if the target machine has register windows.
- This C expression returns true if the register is call-saved but
- is in the register window. Unlike most call-saved registers, such
- registers need not be explicitly restored on function exit or
- during non-local gotos.
-
-
-\1f
-File: gccint.info, Node: Allocation Order, Next: Values in Registers, Prev: Register Basics, Up: Registers
-
-Order of Allocation of Registers
---------------------------------
-
- Registers are allocated in order.
-
-`REG_ALLOC_ORDER'
- If defined, an initializer for a vector of integers, containing the
- numbers of hard registers in the order in which GCC should prefer
- to use them (from most preferred to least).
-
- If this macro is not defined, registers are used lowest numbered
- first (all else being equal).
-
- One use of this macro is on machines where the highest numbered
- registers must always be saved and the save-multiple-registers
- instruction supports only sequences of consecutive registers. On
- such machines, define `REG_ALLOC_ORDER' to be an initializer that
- lists the highest numbered allocable register first.
-
-`ORDER_REGS_FOR_LOCAL_ALLOC'
- A C statement (sans semicolon) to choose the order in which to
- allocate hard registers for pseudo-registers local to a basic
- block.
-
- Store the desired register order in the array `reg_alloc_order'.
- Element 0 should be the register to allocate first; element 1, the
- next register; and so on.
-
- The macro body should not assume anything about the contents of
- `reg_alloc_order' before execution of the macro.
-
- On most machines, it is not necessary to define this macro.
-
-\1f
-File: gccint.info, Node: Values in Registers, Next: Leaf Functions, Prev: Allocation Order, Up: Registers
-
-How Values Fit in Registers
----------------------------
-
- This section discusses the macros that describe which kinds of values
-(specifically, which machine modes) each register can hold, and how many
-consecutive registers are needed for a given mode.
-
-`HARD_REGNO_NREGS (REGNO, MODE)'
- A C expression for the number of consecutive hard registers,
- starting at register number REGNO, required to hold a value of mode
- MODE.
-
- On a machine where all registers are exactly one word, a suitable
- definition of this macro is
-
- #define HARD_REGNO_NREGS(REGNO, MODE) \
- ((GET_MODE_SIZE (MODE) + UNITS_PER_WORD - 1) \
- / UNITS_PER_WORD)
-
-`HARD_REGNO_MODE_OK (REGNO, MODE)'
- A C expression that is nonzero if it is permissible to store a
- value of mode MODE in hard register number REGNO (or in several
- registers starting with that one). For a machine where all
- registers are equivalent, a suitable definition is
-
- #define HARD_REGNO_MODE_OK(REGNO, MODE) 1
-
- You need not include code to check for the numbers of fixed
- registers, because the allocation mechanism considers them to be
- always occupied.
-
- On some machines, double-precision values must be kept in even/odd
- register pairs. You can implement that by defining this macro to
- reject odd register numbers for such modes.
-
- The minimum requirement for a mode to be OK in a register is that
- the `movMODE' instruction pattern support moves between the
- register and other hard register in the same class and that moving
- a value into the register and back out not alter it.
-
- Since the same instruction used to move `word_mode' will work for
- all narrower integer modes, it is not necessary on any machine for
- `HARD_REGNO_MODE_OK' to distinguish between these modes, provided
- you define patterns `movhi', etc., to take advantage of this. This
- is useful because of the interaction between `HARD_REGNO_MODE_OK'
- and `MODES_TIEABLE_P'; it is very desirable for all integer modes
- to be tieable.
-
- Many machines have special registers for floating point arithmetic.
- Often people assume that floating point machine modes are allowed
- only in floating point registers. This is not true. Any
- registers that can hold integers can safely _hold_ a floating
- point machine mode, whether or not floating arithmetic can be done
- on it in those registers. Integer move instructions can be used
- to move the values.
-
- On some machines, though, the converse is true: fixed-point machine
- modes may not go in floating registers. This is true if the
- floating registers normalize any value stored in them, because
- storing a non-floating value there would garble it. In this case,
- `HARD_REGNO_MODE_OK' should reject fixed-point machine modes in
- floating registers. But if the floating registers do not
- automatically normalize, if you can store any bit pattern in one
- and retrieve it unchanged without a trap, then any machine mode
- may go in a floating register, so you can define this macro to say
- so.
-
- The primary significance of special floating registers is rather
- that they are the registers acceptable in floating point arithmetic
- instructions. However, this is of no concern to
- `HARD_REGNO_MODE_OK'. You handle it by writing the proper
- constraints for those instructions.
-
- On some machines, the floating registers are especially slow to
- access, so that it is better to store a value in a stack frame
- than in such a register if floating point arithmetic is not being
- done. As long as the floating registers are not in class
- `GENERAL_REGS', they will not be used unless some pattern's
- constraint asks for one.
-
-`MODES_TIEABLE_P (MODE1, MODE2)'
- A C expression that is nonzero if a value of mode MODE1 is
- accessible in mode MODE2 without copying.
-
- If `HARD_REGNO_MODE_OK (R, MODE1)' and `HARD_REGNO_MODE_OK (R,
- MODE2)' are always the same for any R, then `MODES_TIEABLE_P
- (MODE1, MODE2)' should be nonzero. If they differ for any R, you
- should define this macro to return zero unless some other
- mechanism ensures the accessibility of the value in a narrower
- mode.
-
- You should define this macro to return nonzero in as many cases as
- possible since doing so will allow GCC to perform better register
- allocation.
-
-`AVOID_CCMODE_COPIES'
- Define this macro if the compiler should avoid copies to/from
- `CCmode' registers. You should only define this macro if support
- for copying to/from `CCmode' is incomplete.
-
-\1f
-File: gccint.info, Node: Leaf Functions, Next: Stack Registers, Prev: Values in Registers, Up: Registers
-
-Handling Leaf Functions
------------------------
-
- On some machines, a leaf function (i.e., one which makes no calls)
-can run more efficiently if it does not make its own register window.
-Often this means it is required to receive its arguments in the
-registers where they are passed by the caller, instead of the registers
-where they would normally arrive.
-
- The special treatment for leaf functions generally applies only when
-other conditions are met; for example, often they may use only those
-registers for its own variables and temporaries. We use the term "leaf
-function" to mean a function that is suitable for this special
-handling, so that functions with no calls are not necessarily "leaf
-functions".
-
- GCC assigns register numbers before it knows whether the function is
-suitable for leaf function treatment. So it needs to renumber the
-registers in order to output a leaf function. The following macros
-accomplish this.
-
-`LEAF_REGISTERS'
- Name of a char vector, indexed by hard register number, which
- contains 1 for a register that is allowable in a candidate for leaf
- function treatment.
-
- If leaf function treatment involves renumbering the registers,
- then the registers marked here should be the ones before
- renumbering--those that GCC would ordinarily allocate. The
- registers which will actually be used in the assembler code, after
- renumbering, should not be marked with 1 in this vector.
-
- Define this macro only if the target machine offers a way to
- optimize the treatment of leaf functions.
-
-`LEAF_REG_REMAP (REGNO)'
- A C expression whose value is the register number to which REGNO
- should be renumbered, when a function is treated as a leaf
- function.
-
- If REGNO is a register number which should not appear in a leaf
- function before renumbering, then the expression should yield -1,
- which will cause the compiler to abort.
-
- Define this macro only if the target machine offers a way to
- optimize the treatment of leaf functions, and registers need to be
- renumbered to do this.
-
- `TARGET_ASM_FUNCTION_PROLOGUE' and `TARGET_ASM_FUNCTION_EPILOGUE'
-must usually treat leaf functions specially. They can test the C
-variable `current_function_is_leaf' which is nonzero for leaf
-functions. `current_function_is_leaf' is set prior to local register
-allocation and is valid for the remaining compiler passes. They can
-also test the C variable `current_function_uses_only_leaf_regs' which
-is nonzero for leaf functions which only use leaf registers.
-`current_function_uses_only_leaf_regs' is valid after reload and is
-only useful if `LEAF_REGISTERS' is defined.
-
-\1f
-File: gccint.info, Node: Stack Registers, Prev: Leaf Functions, Up: Registers
-
-Registers That Form a Stack
----------------------------
-
- There are special features to handle computers where some of the
-"registers" form a stack, as in the 80387 coprocessor for the 80386.
-Stack registers are normally written by pushing onto the stack, and are
-numbered relative to the top of the stack.
-
- Currently, GCC can only handle one group of stack-like registers, and
-they must be consecutively numbered.
-
-`STACK_REGS'
- Define this if the machine has any stack-like registers.
-
-`FIRST_STACK_REG'
- The number of the first stack-like register. This one is the top
- of the stack.
-
-`LAST_STACK_REG'
- The number of the last stack-like register. This one is the
- bottom of the stack.
-
-\1f
-File: gccint.info, Node: Register Classes, Next: Stack and Calling, Prev: Registers, Up: Target Macros
-
-Register Classes
-================
-
- On many machines, the numbered registers are not all equivalent.
-For example, certain registers may not be allowed for indexed
-addressing; certain registers may not be allowed in some instructions.
-These machine restrictions are described to the compiler using
-"register classes".
-
- You define a number of register classes, giving each one a name and
-saying which of the registers belong to it. Then you can specify
-register classes that are allowed as operands to particular instruction
-patterns.
-
- In general, each register will belong to several classes. In fact,
-one class must be named `ALL_REGS' and contain all the registers.
-Another class must be named `NO_REGS' and contain no registers. Often
-the union of two classes will be another class; however, this is not
-required.
-
- One of the classes must be named `GENERAL_REGS'. There is nothing
-terribly special about the name, but the operand constraint letters `r'
-and `g' specify this class. If `GENERAL_REGS' is the same as
-`ALL_REGS', just define it as a macro which expands to `ALL_REGS'.
-
- Order the classes so that if class X is contained in class Y then X
-has a lower class number than Y.
-
- The way classes other than `GENERAL_REGS' are specified in operand
-constraints is through machine-dependent operand constraint letters.
-You can define such letters to correspond to various classes, then use
-them in operand constraints.
-
- You should define a class for the union of two classes whenever some
-instruction allows both classes. For example, if an instruction allows
-either a floating point (coprocessor) register or a general register
-for a certain operand, you should define a class `FLOAT_OR_GENERAL_REGS'
-which includes both of them. Otherwise you will get suboptimal code.
-
- You must also specify certain redundant information about the
-register classes: for each class, which classes contain it and which
-ones are contained in it; for each pair of classes, the largest class
-contained in their union.
-
- When a value occupying several consecutive registers is expected in a
-certain class, all the registers used must belong to that class.
-Therefore, register classes cannot be used to enforce a requirement for
-a register pair to start with an even-numbered register. The way to
-specify this requirement is with `HARD_REGNO_MODE_OK'.
-
- Register classes used for input-operands of bitwise-and or shift
-instructions have a special requirement: each such class must have, for
-each fixed-point machine mode, a subclass whose registers can transfer
-that mode to or from memory. For example, on some machines, the
-operations for single-byte values (`QImode') are limited to certain
-registers. When this is so, each register class that is used in a
-bitwise-and or shift instruction must have a subclass consisting of
-registers from which single-byte values can be loaded or stored. This
-is so that `PREFERRED_RELOAD_CLASS' can always have a possible value to
-return.
-
-`enum reg_class'
- An enumeral type that must be defined with all the register class
- names as enumeral values. `NO_REGS' must be first. `ALL_REGS'
- must be the last register class, followed by one more enumeral
- value, `LIM_REG_CLASSES', which is not a register class but rather
- tells how many classes there are.
-
- Each register class has a number, which is the value of casting
- the class name to type `int'. The number serves as an index in
- many of the tables described below.
-
-`N_REG_CLASSES'
- The number of distinct register classes, defined as follows:
-
- #define N_REG_CLASSES (int) LIM_REG_CLASSES
-
-`REG_CLASS_NAMES'
- An initializer containing the names of the register classes as C
- string constants. These names are used in writing some of the
- debugging dumps.
-
-`REG_CLASS_CONTENTS'
- An initializer containing the contents of the register classes, as
- integers which are bit masks. The Nth integer specifies the
- contents of class N. The way the integer MASK is interpreted is
- that register R is in the class if `MASK & (1 << R)' is 1.
-
- When the machine has more than 32 registers, an integer does not
- suffice. Then the integers are replaced by sub-initializers,
- braced groupings containing several integers. Each
- sub-initializer must be suitable as an initializer for the type
- `HARD_REG_SET' which is defined in `hard-reg-set.h'. In this
- situation, the first integer in each sub-initializer corresponds to
- registers 0 through 31, the second integer to registers 32 through
- 63, and so on.
-
-`REGNO_REG_CLASS (REGNO)'
- A C expression whose value is a register class containing hard
- register REGNO. In general there is more than one such class;
- choose a class which is "minimal", meaning that no smaller class
- also contains the register.
-
-`BASE_REG_CLASS'
- A macro whose definition is the name of the class to which a valid
- base register must belong. A base register is one used in an
- address which is the register value plus a displacement.
-
-`MODE_BASE_REG_CLASS (MODE)'
- This is a variation of the `BASE_REG_CLASS' macro which allows the
- selection of a base register in a mode depenedent manner. If MODE
- is VOIDmode then it should return the same value as
- `BASE_REG_CLASS'.
-
-`INDEX_REG_CLASS'
- A macro whose definition is the name of the class to which a valid
- index register must belong. An index register is one used in an
- address where its value is either multiplied by a scale factor or
- added to another register (as well as added to a displacement).
-
-`REG_CLASS_FROM_LETTER (CHAR)'
- A C expression which defines the machine-dependent operand
- constraint letters for register classes. If CHAR is such a
- letter, the value should be the register class corresponding to
- it. Otherwise, the value should be `NO_REGS'. The register
- letter `r', corresponding to class `GENERAL_REGS', will not be
- passed to this macro; you do not need to handle it.
-
-`REGNO_OK_FOR_BASE_P (NUM)'
- A C expression which is nonzero if register number NUM is suitable
- for use as a base register in operand addresses. It may be either
- a suitable hard register or a pseudo register that has been
- allocated such a hard register.
-
-`REGNO_MODE_OK_FOR_BASE_P (NUM, MODE)'
- A C expression that is just like `REGNO_OK_FOR_BASE_P', except that
- that expression may examine the mode of the memory reference in
- MODE. You should define this macro if the mode of the memory
- reference affects whether a register may be used as a base
- register. If you define this macro, the compiler will use it
- instead of `REGNO_OK_FOR_BASE_P'.
-
-`REGNO_OK_FOR_INDEX_P (NUM)'
- A C expression which is nonzero if register number NUM is suitable
- for use as an index register in operand addresses. It may be
- either a suitable hard register or a pseudo register that has been
- allocated such a hard register.
-
- The difference between an index register and a base register is
- that the index register may be scaled. If an address involves the
- sum of two registers, neither one of them scaled, then either one
- may be labeled the "base" and the other the "index"; but whichever
- labeling is used must fit the machine's constraints of which
- registers may serve in each capacity. The compiler will try both
- labelings, looking for one that is valid, and will reload one or
- both registers only if neither labeling works.
-
-`PREFERRED_RELOAD_CLASS (X, CLASS)'
- A C expression that places additional restrictions on the register
- class to use when it is necessary to copy value X into a register
- in class CLASS. The value is a register class; perhaps CLASS, or
- perhaps another, smaller class. On many machines, the following
- definition is safe:
-
- #define PREFERRED_RELOAD_CLASS(X,CLASS) CLASS
-
- Sometimes returning a more restrictive class makes better code.
- For example, on the 68000, when X is an integer constant that is
- in range for a `moveq' instruction, the value of this macro is
- always `DATA_REGS' as long as CLASS includes the data registers.
- Requiring a data register guarantees that a `moveq' will be used.
-
- If X is a `const_double', by returning `NO_REGS' you can force X
- into a memory constant. This is useful on certain machines where
- immediate floating values cannot be loaded into certain kinds of
- registers.
-
-`PREFERRED_OUTPUT_RELOAD_CLASS (X, CLASS)'
- Like `PREFERRED_RELOAD_CLASS', but for output reloads instead of
- input reloads. If you don't define this macro, the default is to
- use CLASS, unchanged.
-
-`LIMIT_RELOAD_CLASS (MODE, CLASS)'
- A C expression that places additional restrictions on the register
- class to use when it is necessary to be able to hold a value of
- mode MODE in a reload register for which class CLASS would
- ordinarily be used.
-
- Unlike `PREFERRED_RELOAD_CLASS', this macro should be used when
- there are certain modes that simply can't go in certain reload
- classes.
-
- The value is a register class; perhaps CLASS, or perhaps another,
- smaller class.
-
- Don't define this macro unless the target machine has limitations
- which require the macro to do something nontrivial.
-
-`SECONDARY_RELOAD_CLASS (CLASS, MODE, X)'
-`SECONDARY_INPUT_RELOAD_CLASS (CLASS, MODE, X)'
-`SECONDARY_OUTPUT_RELOAD_CLASS (CLASS, MODE, X)'
- Many machines have some registers that cannot be copied directly
- to or from memory or even from other types of registers. An
- example is the `MQ' register, which on most machines, can only be
- copied to or from general registers, but not memory. Some
- machines allow copying all registers to and from memory, but
- require a scratch register for stores to some memory locations
- (e.g., those with symbolic address on the RT, and those with
- certain symbolic address on the Sparc when compiling PIC). In
- some cases, both an intermediate and a scratch register are
- required.
-
- You should define these macros to indicate to the reload phase
- that it may need to allocate at least one register for a reload in
- addition to the register to contain the data. Specifically, if
- copying X to a register CLASS in MODE requires an intermediate
- register, you should define `SECONDARY_INPUT_RELOAD_CLASS' to
- return the largest register class all of whose registers can be
- used as intermediate registers or scratch registers.
-
- If copying a register CLASS in MODE to X requires an intermediate
- or scratch register, `SECONDARY_OUTPUT_RELOAD_CLASS' should be
- defined to return the largest register class required. If the
- requirements for input and output reloads are the same, the macro
- `SECONDARY_RELOAD_CLASS' should be used instead of defining both
- macros identically.
-
- The values returned by these macros are often `GENERAL_REGS'.
- Return `NO_REGS' if no spare register is needed; i.e., if X can be
- directly copied to or from a register of CLASS in MODE without
- requiring a scratch register. Do not define this macro if it
- would always return `NO_REGS'.
-
- If a scratch register is required (either with or without an
- intermediate register), you should define patterns for
- `reload_inM' or `reload_outM', as required (*note Standard
- Names::. These patterns, which will normally be implemented with
- a `define_expand', should be similar to the `movM' patterns,
- except that operand 2 is the scratch register.
-
- Define constraints for the reload register and scratch register
- that contain a single register class. If the original reload
- register (whose class is CLASS) can meet the constraint given in
- the pattern, the value returned by these macros is used for the
- class of the scratch register. Otherwise, two additional reload
- registers are required. Their classes are obtained from the
- constraints in the insn pattern.
-
- X might be a pseudo-register or a `subreg' of a pseudo-register,
- which could either be in a hard register or in memory. Use
- `true_regnum' to find out; it will return -1 if the pseudo is in
- memory and the hard register number if it is in a register.
-
- These macros should not be used in the case where a particular
- class of registers can only be copied to memory and not to another
- class of registers. In that case, secondary reload registers are
- not needed and would not be helpful. Instead, a stack location
- must be used to perform the copy and the `movM' pattern should use
- memory as an intermediate storage. This case often occurs between
- floating-point and general registers.
-
-`SECONDARY_MEMORY_NEEDED (CLASS1, CLASS2, M)'
- Certain machines have the property that some registers cannot be
- copied to some other registers without using memory. Define this
- macro on those machines to be a C expression that is nonzero if
- objects of mode M in registers of CLASS1 can only be copied to
- registers of class CLASS2 by storing a register of CLASS1 into
- memory and loading that memory location into a register of CLASS2.
-
- Do not define this macro if its value would always be zero.
-
-`SECONDARY_MEMORY_NEEDED_RTX (MODE)'
- Normally when `SECONDARY_MEMORY_NEEDED' is defined, the compiler
- allocates a stack slot for a memory location needed for register
- copies. If this macro is defined, the compiler instead uses the
- memory location defined by this macro.
-
- Do not define this macro if you do not define
- `SECONDARY_MEMORY_NEEDED'.
-
-`SECONDARY_MEMORY_NEEDED_MODE (MODE)'
- When the compiler needs a secondary memory location to copy
- between two registers of mode MODE, it normally allocates
- sufficient memory to hold a quantity of `BITS_PER_WORD' bits and
- performs the store and load operations in a mode that many bits
- wide and whose class is the same as that of MODE.
-
- This is right thing to do on most machines because it ensures that
- all bits of the register are copied and prevents accesses to the
- registers in a narrower mode, which some machines prohibit for
- floating-point registers.
-
- However, this default behavior is not correct on some machines,
- such as the DEC Alpha, that store short integers in floating-point
- registers differently than in integer registers. On those
- machines, the default widening will not work correctly and you
- must define this macro to suppress that widening in some cases.
- See the file `alpha.h' for details.
-
- Do not define this macro if you do not define
- `SECONDARY_MEMORY_NEEDED' or if widening MODE to a mode that is
- `BITS_PER_WORD' bits wide is correct for your machine.
-
-`SMALL_REGISTER_CLASSES'
- On some machines, it is risky to let hard registers live across
- arbitrary insns. Typically, these machines have instructions that
- require values to be in specific registers (like an accumulator),
- and reload will fail if the required hard register is used for
- another purpose across such an insn.
-
- Define `SMALL_REGISTER_CLASSES' to be an expression with a nonzero
- value on these machines. When this macro has a nonzero value, the
- compiler will try to minimize the lifetime of hard registers.
-
- It is always safe to define this macro with a nonzero value, but
- if you unnecessarily define it, you will reduce the amount of
- optimizations that can be performed in some cases. If you do not
- define this macro with a nonzero value when it is required, the
- compiler will run out of spill registers and print a fatal error
- message. For most machines, you should not define this macro at
- all.
-
-`CLASS_LIKELY_SPILLED_P (CLASS)'
- A C expression whose value is nonzero if pseudos that have been
- assigned to registers of class CLASS would likely be spilled
- because registers of CLASS are needed for spill registers.
-
- The default value of this macro returns 1 if CLASS has exactly one
- register and zero otherwise. On most machines, this default
- should be used. Only define this macro to some other expression
- if pseudos allocated by `local-alloc.c' end up in memory because
- their hard registers were needed for spill registers. If this
- macro returns nonzero for those classes, those pseudos will only
- be allocated by `global.c', which knows how to reallocate the
- pseudo to another register. If there would not be another
- register available for reallocation, you should not change the
- definition of this macro since the only effect of such a
- definition would be to slow down register allocation.
-
-`CLASS_MAX_NREGS (CLASS, MODE)'
- A C expression for the maximum number of consecutive registers of
- class CLASS needed to hold a value of mode MODE.
-
- This is closely related to the macro `HARD_REGNO_NREGS'. In fact,
- the value of the macro `CLASS_MAX_NREGS (CLASS, MODE)' should be
- the maximum value of `HARD_REGNO_NREGS (REGNO, MODE)' for all
- REGNO values in the class CLASS.
-
- This macro helps control the handling of multiple-word values in
- the reload pass.
-
-`CLASS_CANNOT_CHANGE_MODE'
- If defined, a C expression for a class that contains registers for
- which the compiler may not change modes arbitrarily.
-
-`CLASS_CANNOT_CHANGE_MODE_P(FROM, TO)'
- A C expression that is true if, for a register in
- `CLASS_CANNOT_CHANGE_MODE', the requested mode punning is invalid.
-
- For the example, loading 32-bit integer or floating-point objects
- into floating-point registers on the Alpha extends them to 64 bits.
- Therefore loading a 64-bit object and then storing it as a 32-bit
- object does not store the low-order 32 bits, as would be the case
- for a normal register. Therefore, `alpha.h' defines
- `CLASS_CANNOT_CHANGE_MODE' as `FLOAT_REGS' and
- `CLASS_CANNOT_CHANGE_MODE_P' restricts mode changes to same-size
- modes.
-
- Compare this to IA-64, which extends floating-point values to 82
- bits, and stores 64-bit integers in a different format than 64-bit
- doubles. Therefore `CLASS_CANNOT_CHANGE_MODE_P' is always true.
-
- Three other special macros describe which operands fit which
-constraint letters.
-
-`CONST_OK_FOR_LETTER_P (VALUE, C)'
- A C expression that defines the machine-dependent operand
- constraint letters (`I', `J', `K', ... `P') that specify
- particular ranges of integer values. If C is one of those
- letters, the expression should check that VALUE, an integer, is in
- the appropriate range and return 1 if so, 0 otherwise. If C is
- not one of those letters, the value should be 0 regardless of
- VALUE.
-
-`CONST_DOUBLE_OK_FOR_LETTER_P (VALUE, C)'
- A C expression that defines the machine-dependent operand
- constraint letters that specify particular ranges of
- `const_double' values (`G' or `H').
-
- If C is one of those letters, the expression should check that
- VALUE, an RTX of code `const_double', is in the appropriate range
- and return 1 if so, 0 otherwise. If C is not one of those
- letters, the value should be 0 regardless of VALUE.
-
- `const_double' is used for all floating-point constants and for
- `DImode' fixed-point constants. A given letter can accept either
- or both kinds of values. It can use `GET_MODE' to distinguish
- between these kinds.
-
-`EXTRA_CONSTRAINT (VALUE, C)'
- A C expression that defines the optional machine-dependent
- constraint letters that can be used to segregate specific types of
- operands, usually memory references, for the target machine. Any
- letter that is not elsewhere defined and not matched by
- `REG_CLASS_FROM_LETTER' may be used. Normally this macro will not
- be defined.
-
- If it is required for a particular target machine, it should
- return 1 if VALUE corresponds to the operand type represented by
- the constraint letter C. If C is not defined as an extra
- constraint, the value returned should be 0 regardless of VALUE.
-
- For example, on the ROMP, load instructions cannot have their
- output in r0 if the memory reference contains a symbolic address.
- Constraint letter `Q' is defined as representing a memory address
- that does _not_ contain a symbolic address. An alternative is
- specified with a `Q' constraint on the input and `r' on the
- output. The next alternative specifies `m' on the input and a
- register class that does not include r0 on the output.
-
-\1f
-File: gccint.info, Node: Stack and Calling, Next: Varargs, Prev: Register Classes, Up: Target Macros
-
-Stack Layout and Calling Conventions
-====================================
-
- This describes the stack layout and calling conventions.
-
-* Menu:
-
-* Frame Layout::
-* Exception Handling::
-* Stack Checking::
-* Frame Registers::
-* Elimination::
-* Stack Arguments::
-* Register Arguments::
-* Scalar Return::
-* Aggregate Return::
-* Caller Saves::
-* Function Entry::
-* Profiling::
-* Tail Calls::
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Frame Layout, Next: Exception Handling, Up: Stack and Calling
-
-Basic Stack Layout
-------------------
-
- Here is the basic stack layout.
-
-`STACK_GROWS_DOWNWARD'
- Define this macro if pushing a word onto the stack moves the stack
- pointer to a smaller address.
-
- When we say, "define this macro if ...," it means that the
- compiler checks this macro only with `#ifdef' so the precise
- definition used does not matter.
-
-`STACK_PUSH_CODE'
- This macro defines the operation used when something is pushed on
- the stack. In RTL, a push operation will be `(set (mem
- (STACK_PUSH_CODE (reg sp))) ...)'
-
- The choices are `PRE_DEC', `POST_DEC', `PRE_INC', and `POST_INC'.
- Which of these is correct depends on the stack direction and on
- whether the stack pointer points to the last item on the stack or
- whether it points to the space for the next item on the stack.
-
- The default is `PRE_DEC' when `STACK_GROWS_DOWNWARD' is defined,
- which is almost always right, and `PRE_INC' otherwise, which is
- often wrong.
-
-`FRAME_GROWS_DOWNWARD'
- Define this macro if the addresses of local variable slots are at
- negative offsets from the frame pointer.
-
-`ARGS_GROW_DOWNWARD'
- Define this macro if successive arguments to a function occupy
- decreasing addresses on the stack.
-
-`STARTING_FRAME_OFFSET'
- Offset from the frame pointer to the first local variable slot to
- be allocated.
-
- If `FRAME_GROWS_DOWNWARD', find the next slot's offset by
- subtracting the first slot's length from `STARTING_FRAME_OFFSET'.
- Otherwise, it is found by adding the length of the first slot to
- the value `STARTING_FRAME_OFFSET'.
-
-`STACK_POINTER_OFFSET'
- Offset from the stack pointer register to the first location at
- which outgoing arguments are placed. If not specified, the
- default value of zero is used. This is the proper value for most
- machines.
-
- If `ARGS_GROW_DOWNWARD', this is the offset to the location above
- the first location at which outgoing arguments are placed.
-
-`FIRST_PARM_OFFSET (FUNDECL)'
- Offset from the argument pointer register to the first argument's
- address. On some machines it may depend on the data type of the
- function.
-
- If `ARGS_GROW_DOWNWARD', this is the offset to the location above
- the first argument's address.
-
-`STACK_DYNAMIC_OFFSET (FUNDECL)'
- Offset from the stack pointer register to an item dynamically
- allocated on the stack, e.g., by `alloca'.
-
- The default value for this macro is `STACK_POINTER_OFFSET' plus the
- length of the outgoing arguments. The default is correct for most
- machines. See `function.c' for details.
-
-`DYNAMIC_CHAIN_ADDRESS (FRAMEADDR)'
- A C expression whose value is RTL representing the address in a
- stack frame where the pointer to the caller's frame is stored.
- Assume that FRAMEADDR is an RTL expression for the address of the
- stack frame itself.
-
- If you don't define this macro, the default is to return the value
- of FRAMEADDR--that is, the stack frame address is also the address
- of the stack word that points to the previous frame.
-
-`SETUP_FRAME_ADDRESSES'
- If defined, a C expression that produces the machine-specific code
- to setup the stack so that arbitrary frames can be accessed. For
- example, on the Sparc, we must flush all of the register windows
- to the stack before we can access arbitrary stack frames. You
- will seldom need to define this macro.
-
-`BUILTIN_SETJMP_FRAME_VALUE'
- If defined, a C expression that contains an rtx that is used to
- store the address of the current frame into the built in `setjmp'
- buffer. The default value, `virtual_stack_vars_rtx', is correct
- for most machines. One reason you may need to define this macro
- is if `hard_frame_pointer_rtx' is the appropriate value on your
- machine.
-
-`RETURN_ADDR_RTX (COUNT, FRAMEADDR)'
- A C expression whose value is RTL representing the value of the
- return address for the frame COUNT steps up from the current
- frame, after the prologue. FRAMEADDR is the frame pointer of the
- COUNT frame, or the frame pointer of the COUNT - 1 frame if
- `RETURN_ADDR_IN_PREVIOUS_FRAME' is defined.
-
- The value of the expression must always be the correct address when
- COUNT is zero, but may be `NULL_RTX' if there is not way to
- determine the return address of other frames.
-
-`RETURN_ADDR_IN_PREVIOUS_FRAME'
- Define this if the return address of a particular stack frame is
- accessed from the frame pointer of the previous stack frame.
-
-`INCOMING_RETURN_ADDR_RTX'
- A C expression whose value is RTL representing the location of the
- incoming return address at the beginning of any function, before
- the prologue. This RTL is either a `REG', indicating that the
- return value is saved in `REG', or a `MEM' representing a location
- in the stack.
-
- You only need to define this macro if you want to support call
- frame debugging information like that provided by DWARF 2.
-
- If this RTL is a `REG', you should also define
- `DWARF_FRAME_RETURN_COLUMN' to `DWARF_FRAME_REGNUM (REGNO)'.
-
-`INCOMING_FRAME_SP_OFFSET'
- A C expression whose value is an integer giving the offset, in
- bytes, from the value of the stack pointer register to the top of
- the stack frame at the beginning of any function, before the
- prologue. The top of the frame is defined to be the value of the
- stack pointer in the previous frame, just before the call
- instruction.
-
- You only need to define this macro if you want to support call
- frame debugging information like that provided by DWARF 2.
-
-`ARG_POINTER_CFA_OFFSET (FUNDECL)'
- A C expression whose value is an integer giving the offset, in
- bytes, from the argument pointer to the canonical frame address
- (cfa). The final value should coincide with that calculated by
- `INCOMING_FRAME_SP_OFFSET'. Which is unfortunately not usable
- during virtual register instantiation.
-
- The default value for this macro is `FIRST_PARM_OFFSET (fundecl)',
- which is correct for most machines; in general, the arguments are
- found immediately before the stack frame. Note that this is not
- the case on some targets that save registers into the caller's
- frame, such as SPARC and rs6000, and so such targets need to
- define this macro.
-
- You only need to define this macro if the default is incorrect,
- and you want to support call frame debugging information like that
- provided by DWARF 2.
-
-`SMALL_STACK'
- Define this macro if the stack size for the target is very small.
- This has the effect of disabling gcc's built-in `alloca', though
- `__builtin_alloca' is not affected.
-
-\1f
-File: gccint.info, Node: Exception Handling, Next: Stack Checking, Prev: Frame Layout, Up: Stack and Calling
-
-Exception Handling Support
---------------------------
-
-`EH_RETURN_DATA_REGNO (N)'
- A C expression whose value is the Nth register number used for
- data by exception handlers, or `INVALID_REGNUM' if fewer than N
- registers are usable.
-
- The exception handling library routines communicate with the
- exception handlers via a set of agreed upon registers. Ideally
- these registers should be call-clobbered; it is possible to use
- call-saved registers, but may negatively impact code size. The
- target must support at least 2 data registers, but should define 4
- if there are enough free registers.
-
- You must define this macro if you want to support call frame
- exception handling like that provided by DWARF 2.
-
-`EH_RETURN_STACKADJ_RTX'
- A C expression whose value is RTL representing a location in which
- to store a stack adjustment to be applied before function return.
- This is used to unwind the stack to an exception handler's call
- frame. It will be assigned zero on code paths that return
- normally.
-
- Typically this is a call-clobbered hard register that is otherwise
- untouched by the epilogue, but could also be a stack slot.
-
- You must define this macro if you want to support call frame
- exception handling like that provided by DWARF 2.
-
-`EH_RETURN_HANDLER_RTX'
- A C expression whose value is RTL representing a location in which
- to store the address of an exception handler to which we should
- return. It will not be assigned on code paths that return
- normally.
-
- Typically this is the location in the call frame at which the
- normal return address is stored. For targets that return by
- popping an address off the stack, this might be a memory address
- just below the _target_ call frame rather than inside the current
- call frame. `EH_RETURN_STACKADJ_RTX' will have already been
- assigned, so it may be used to calculate the location of the
- target call frame.
-
- Some targets have more complex requirements than storing to an
- address calculable during initial code generation. In that case
- the `eh_return' instruction pattern should be used instead.
-
- If you want to support call frame exception handling, you must
- define either this macro or the `eh_return' instruction pattern.
-
-`ASM_PREFERRED_EH_DATA_FORMAT(CODE, GLOBAL)'
- This macro chooses the encoding of pointers embedded in the
- exception handling sections. If at all possible, this should be
- defined such that the exception handling section will not require
- dynamic relocations, and so may be read-only.
-
- CODE is 0 for data, 1 for code labels, 2 for function pointers.
- GLOBAL is true if the symbol may be affected by dynamic
- relocations. The macro should return a combination of the
- `DW_EH_PE_*' defines as found in `dwarf2.h'.
-
- If this macro is not defined, pointers will not be encoded but
- represented directly.
-
-`ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX(FILE, ENCODING, SIZE, ADDR, DONE)'
- This macro allows the target to emit whatever special magic is
- required to represent the encoding chosen by
- `ASM_PREFERRED_EH_DATA_FORMAT'. Generic code takes care of
- pc-relative and indirect encodings; this must be defined if the
- target uses text-relative or data-relative encodings.
-
- This is a C statement that branches to DONE if the format was
- handled. ENCODING is the format chosen, SIZE is the number of
- bytes that the format occupies, ADDR is the `SYMBOL_REF' to be
- emitted.
-
-`MD_FALLBACK_FRAME_STATE_FOR(CONTEXT, FS, SUCCESS)'
- This macro allows the target to add cpu and operating system
- specific code to the call-frame unwinder for use when there is no
- unwind data available. The most common reason to implement this
- macro is to unwind through signal frames.
-
- This macro is called from `uw_frame_state_for' in `unwind-dw2.c'
- and `unwind-ia64.c'. CONTEXT is an `_Unwind_Context'; FS is an
- `_Unwind_FrameState'. Examine `context->ra' for the address of
- the code being executed and `context->cfa' for the stack pointer
- value. If the frame can be decoded, the register save addresses
- should be updated in FS and the macro should branch to SUCCESS.
- If the frame cannot be decoded, the macro should do nothing.
-
-\1f
-File: gccint.info, Node: Stack Checking, Next: Frame Registers, Prev: Exception Handling, Up: Stack and Calling
-
-Specifying How Stack Checking is Done
--------------------------------------
-
- GCC will check that stack references are within the boundaries of
-the stack, if the `-fstack-check' is specified, in one of three ways:
-
- 1. If the value of the `STACK_CHECK_BUILTIN' macro is nonzero, GCC
- will assume that you have arranged for stack checking to be done at
- appropriate places in the configuration files, e.g., in
- `TARGET_ASM_FUNCTION_PROLOGUE'. GCC will do not other special
- processing.
-
- 2. If `STACK_CHECK_BUILTIN' is zero and you defined a named pattern
- called `check_stack' in your `md' file, GCC will call that pattern
- with one argument which is the address to compare the stack value
- against. You must arrange for this pattern to report an error if
- the stack pointer is out of range.
-
- 3. If neither of the above are true, GCC will generate code to
- periodically "probe" the stack pointer using the values of the
- macros defined below.
-
- Normally, you will use the default values of these macros, so GCC
-will use the third approach.
-
-`STACK_CHECK_BUILTIN'
- A nonzero value if stack checking is done by the configuration
- files in a machine-dependent manner. You should define this macro
- if stack checking is require by the ABI of your machine or if you
- would like to have to stack checking in some more efficient way
- than GCC's portable approach. The default value of this macro is
- zero.
-
-`STACK_CHECK_PROBE_INTERVAL'
- An integer representing the interval at which GCC must generate
- stack probe instructions. You will normally define this macro to
- be no larger than the size of the "guard pages" at the end of a
- stack area. The default value of 4096 is suitable for most
- systems.
-
-`STACK_CHECK_PROBE_LOAD'
- A integer which is nonzero if GCC should perform the stack probe
- as a load instruction and zero if GCC should use a store
- instruction. The default is zero, which is the most efficient
- choice on most systems.
-
-`STACK_CHECK_PROTECT'
- The number of bytes of stack needed to recover from a stack
- overflow, for languages where such a recovery is supported. The
- default value of 75 words should be adequate for most machines.
-
-`STACK_CHECK_MAX_FRAME_SIZE'
- The maximum size of a stack frame, in bytes. GCC will generate
- probe instructions in non-leaf functions to ensure at least this
- many bytes of stack are available. If a stack frame is larger
- than this size, stack checking will not be reliable and GCC will
- issue a warning. The default is chosen so that GCC only generates
- one instruction on most systems. You should normally not change
- the default value of this macro.
-
-`STACK_CHECK_FIXED_FRAME_SIZE'
- GCC uses this value to generate the above warning message. It
- represents the amount of fixed frame used by a function, not
- including space for any callee-saved registers, temporaries and
- user variables. You need only specify an upper bound for this
- amount and will normally use the default of four words.
-
-`STACK_CHECK_MAX_VAR_SIZE'
- The maximum size, in bytes, of an object that GCC will place in the
- fixed area of the stack frame when the user specifies
- `-fstack-check'. GCC computed the default from the values of the
- above macros and you will normally not need to override that
- default.
-
-\1f
-File: gccint.info, Node: Frame Registers, Next: Elimination, Prev: Stack Checking, Up: Stack and Calling
-
-Registers That Address the Stack Frame
---------------------------------------
-
- This discusses registers that address the stack frame.
-
-`STACK_POINTER_REGNUM'
- The register number of the stack pointer register, which must also
- be a fixed register according to `FIXED_REGISTERS'. On most
- machines, the hardware determines which register this is.
-
-`FRAME_POINTER_REGNUM'
- The register number of the frame pointer register, which is used to
- access automatic variables in the stack frame. On some machines,
- the hardware determines which register this is. On other
- machines, you can choose any register you wish for this purpose.
-
-`HARD_FRAME_POINTER_REGNUM'
- On some machines the offset between the frame pointer and starting
- offset of the automatic variables is not known until after register
- allocation has been done (for example, because the saved registers
- are between these two locations). On those machines, define
- `FRAME_POINTER_REGNUM' the number of a special, fixed register to
- be used internally until the offset is known, and define
- `HARD_FRAME_POINTER_REGNUM' to be the actual hard register number
- used for the frame pointer.
-
- You should define this macro only in the very rare circumstances
- when it is not possible to calculate the offset between the frame
- pointer and the automatic variables until after register
- allocation has been completed. When this macro is defined, you
- must also indicate in your definition of `ELIMINABLE_REGS' how to
- eliminate `FRAME_POINTER_REGNUM' into either
- `HARD_FRAME_POINTER_REGNUM' or `STACK_POINTER_REGNUM'.
-
- Do not define this macro if it would be the same as
- `FRAME_POINTER_REGNUM'.
-
-`ARG_POINTER_REGNUM'
- The register number of the arg pointer register, which is used to
- access the function's argument list. On some machines, this is
- the same as the frame pointer register. On some machines, the
- hardware determines which register this is. On other machines,
- you can choose any register you wish for this purpose. If this is
- not the same register as the frame pointer register, then you must
- mark it as a fixed register according to `FIXED_REGISTERS', or
- arrange to be able to eliminate it (*note Elimination::).
-
-`RETURN_ADDRESS_POINTER_REGNUM'
- The register number of the return address pointer register, which
- is used to access the current function's return address from the
- stack. On some machines, the return address is not at a fixed
- offset from the frame pointer or stack pointer or argument
- pointer. This register can be defined to point to the return
- address on the stack, and then be converted by `ELIMINABLE_REGS'
- into either the frame pointer or stack pointer.
-
- Do not define this macro unless there is no other way to get the
- return address from the stack.
-
-`STATIC_CHAIN_REGNUM'
-`STATIC_CHAIN_INCOMING_REGNUM'
- Register numbers used for passing a function's static chain
- pointer. If register windows are used, the register number as
- seen by the called function is `STATIC_CHAIN_INCOMING_REGNUM',
- while the register number as seen by the calling function is
- `STATIC_CHAIN_REGNUM'. If these registers are the same,
- `STATIC_CHAIN_INCOMING_REGNUM' need not be defined.
-
- The static chain register need not be a fixed register.
-
- If the static chain is passed in memory, these macros should not be
- defined; instead, the next two macros should be defined.
-
-`STATIC_CHAIN'
-`STATIC_CHAIN_INCOMING'
- If the static chain is passed in memory, these macros provide rtx
- giving `mem' expressions that denote where they are stored.
- `STATIC_CHAIN' and `STATIC_CHAIN_INCOMING' give the locations as
- seen by the calling and called functions, respectively. Often the
- former will be at an offset from the stack pointer and the latter
- at an offset from the frame pointer.
-
- The variables `stack_pointer_rtx', `frame_pointer_rtx', and
- `arg_pointer_rtx' will have been initialized prior to the use of
- these macros and should be used to refer to those items.
-
- If the static chain is passed in a register, the two previous
- macros should be defined instead.
-
-`DWARF_FRAME_REGISTERS'
- This macro specifies the maximum number of hard registers that can
- be saved in a call frame. This is used to size data structures
- used in DWARF2 exception handling.
-
- Prior to GCC 3.0, this macro was needed in order to establish a
- stable exception handling ABI in the face of adding new hard
- registers for ISA extensions. In GCC 3.0 and later, the EH ABI is
- insulated from changes in the number of hard registers.
- Nevertheless, this macro can still be used to reduce the runtime
- memory requirements of the exception handling routines, which can
- be substantial if the ISA contains a lot of registers that are not
- call-saved.
-
- If this macro is not defined, it defaults to
- `FIRST_PSEUDO_REGISTER'.
-
-`PRE_GCC3_DWARF_FRAME_REGISTERS'
- This macro is similar to `DWARF_FRAME_REGISTERS', but is provided
- for backward compatibility in pre GCC 3.0 compiled code.
-
- If this macro is not defined, it defaults to
- `DWARF_FRAME_REGISTERS'.
-
-
-\1f
-File: gccint.info, Node: Elimination, Next: Stack Arguments, Prev: Frame Registers, Up: Stack and Calling
-
-Eliminating Frame Pointer and Arg Pointer
------------------------------------------
-
- This is about eliminating the frame pointer and arg pointer.
-
-`FRAME_POINTER_REQUIRED'
- A C expression which is nonzero if a function must have and use a
- frame pointer. This expression is evaluated in the reload pass.
- If its value is nonzero the function will have a frame pointer.
-
- The expression can in principle examine the current function and
- decide according to the facts, but on most machines the constant 0
- or the constant 1 suffices. Use 0 when the machine allows code to
- be generated with no frame pointer, and doing so saves some time
- or space. Use 1 when there is no possible advantage to avoiding a
- frame pointer.
-
- In certain cases, the compiler does not know how to produce valid
- code without a frame pointer. The compiler recognizes those cases
- and automatically gives the function a frame pointer regardless of
- what `FRAME_POINTER_REQUIRED' says. You don't need to worry about
- them.
-
- In a function that does not require a frame pointer, the frame
- pointer register can be allocated for ordinary usage, unless you
- mark it as a fixed register. See `FIXED_REGISTERS' for more
- information.
-
-`INITIAL_FRAME_POINTER_OFFSET (DEPTH-VAR)'
- A C statement to store in the variable DEPTH-VAR the difference
- between the frame pointer and the stack pointer values immediately
- after the function prologue. The value would be computed from
- information such as the result of `get_frame_size ()' and the
- tables of registers `regs_ever_live' and `call_used_regs'.
-
- If `ELIMINABLE_REGS' is defined, this macro will be not be used and
- need not be defined. Otherwise, it must be defined even if
- `FRAME_POINTER_REQUIRED' is defined to always be true; in that
- case, you may set DEPTH-VAR to anything.
-
-`ELIMINABLE_REGS'
- If defined, this macro specifies a table of register pairs used to
- eliminate unneeded registers that point into the stack frame. If
- it is not defined, the only elimination attempted by the compiler
- is to replace references to the frame pointer with references to
- the stack pointer.
-
- The definition of this macro is a list of structure
- initializations, each of which specifies an original and
- replacement register.
-
- On some machines, the position of the argument pointer is not
- known until the compilation is completed. In such a case, a
- separate hard register must be used for the argument pointer.
- This register can be eliminated by replacing it with either the
- frame pointer or the argument pointer, depending on whether or not
- the frame pointer has been eliminated.
-
- In this case, you might specify:
- #define ELIMINABLE_REGS \
- {{ARG_POINTER_REGNUM, STACK_POINTER_REGNUM}, \
- {ARG_POINTER_REGNUM, FRAME_POINTER_REGNUM}, \
- {FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM}}
-
- Note that the elimination of the argument pointer with the stack
- pointer is specified first since that is the preferred elimination.
-
-`CAN_ELIMINATE (FROM-REG, TO-REG)'
- A C expression that returns nonzero if the compiler is allowed to
- try to replace register number FROM-REG with register number
- TO-REG. This macro need only be defined if `ELIMINABLE_REGS' is
- defined, and will usually be the constant 1, since most of the
- cases preventing register elimination are things that the compiler
- already knows about.
-
-`INITIAL_ELIMINATION_OFFSET (FROM-REG, TO-REG, OFFSET-VAR)'
- This macro is similar to `INITIAL_FRAME_POINTER_OFFSET'. It
- specifies the initial difference between the specified pair of
- registers. This macro must be defined if `ELIMINABLE_REGS' is
- defined.
-
-\1f
-File: gccint.info, Node: Stack Arguments, Next: Register Arguments, Prev: Elimination, Up: Stack and Calling
-
-Passing Function Arguments on the Stack
----------------------------------------
-
- The macros in this section control how arguments are passed on the
-stack. See the following section for other macros that control passing
-certain arguments in registers.
-
-`PROMOTE_PROTOTYPES'
- A C expression whose value is nonzero if an argument declared in a
- prototype as an integral type smaller than `int' should actually
- be passed as an `int'. In addition to avoiding errors in certain
- cases of mismatch, it also makes for better code on certain
- machines. If the macro is not defined in target header files, it
- defaults to 0.
-
-`PUSH_ARGS'
- A C expression. If nonzero, push insns will be used to pass
- outgoing arguments. If the target machine does not have a push
- instruction, set it to zero. That directs GCC to use an alternate
- strategy: to allocate the entire argument block and then store the
- arguments into it. When `PUSH_ARGS' is nonzero, `PUSH_ROUNDING'
- must be defined too.
-
-`PUSH_ROUNDING (NPUSHED)'
- A C expression that is the number of bytes actually pushed onto the
- stack when an instruction attempts to push NPUSHED bytes.
-
- On some machines, the definition
-
- #define PUSH_ROUNDING(BYTES) (BYTES)
-
- will suffice. But on other machines, instructions that appear to
- push one byte actually push two bytes in an attempt to maintain
- alignment. Then the definition should be
-
- #define PUSH_ROUNDING(BYTES) (((BYTES) + 1) & ~1)
-
-`ACCUMULATE_OUTGOING_ARGS'
- A C expression. If nonzero, the maximum amount of space required
- for outgoing arguments will be computed and placed into the
- variable `current_function_outgoing_args_size'. No space will be
- pushed onto the stack for each call; instead, the function
- prologue should increase the stack frame size by this amount.
-
- Setting both `PUSH_ARGS' and `ACCUMULATE_OUTGOING_ARGS' is not
- proper.
-
-`REG_PARM_STACK_SPACE (FNDECL)'
- Define this macro if functions should assume that stack space has
- been allocated for arguments even when their values are passed in
- registers.
-
- The value of this macro is the size, in bytes, of the area
- reserved for arguments passed in registers for the function
- represented by FNDECL, which can be zero if GCC is calling a
- library function.
-
- This space can be allocated by the caller, or be a part of the
- machine-dependent stack frame: `OUTGOING_REG_PARM_STACK_SPACE' says
- which.
-
-`MAYBE_REG_PARM_STACK_SPACE'
-`FINAL_REG_PARM_STACK_SPACE (CONST_SIZE, VAR_SIZE)'
- Define these macros in addition to the one above if functions might
- allocate stack space for arguments even when their values are
- passed in registers. These should be used when the stack space
- allocated for arguments in registers is not a simple constant
- independent of the function declaration.
-
- The value of the first macro is the size, in bytes, of the area
- that we should initially assume would be reserved for arguments
- passed in registers.
-
- The value of the second macro is the actual size, in bytes, of the
- area that will be reserved for arguments passed in registers.
- This takes two arguments: an integer representing the number of
- bytes of fixed sized arguments on the stack, and a tree
- representing the number of bytes of variable sized arguments on
- the stack.
-
- When these macros are defined, `REG_PARM_STACK_SPACE' will only be
- called for libcall functions, the current function, or for a
- function being called when it is known that such stack space must
- be allocated. In each case this value can be easily computed.
-
- When deciding whether a called function needs such stack space,
- and how much space to reserve, GCC uses these two macros instead of
- `REG_PARM_STACK_SPACE'.
-
-`OUTGOING_REG_PARM_STACK_SPACE'
- Define this if it is the responsibility of the caller to allocate
- the area reserved for arguments passed in registers.
-
- If `ACCUMULATE_OUTGOING_ARGS' is defined, this macro controls
- whether the space for these arguments counts in the value of
- `current_function_outgoing_args_size'.
-
-`STACK_PARMS_IN_REG_PARM_AREA'
- Define this macro if `REG_PARM_STACK_SPACE' is defined, but the
- stack parameters don't skip the area specified by it.
-
- Normally, when a parameter is not passed in registers, it is
- placed on the stack beyond the `REG_PARM_STACK_SPACE' area.
- Defining this macro suppresses this behavior and causes the
- parameter to be passed on the stack in its natural location.
-
-`RETURN_POPS_ARGS (FUNDECL, FUNTYPE, STACK-SIZE)'
- A C expression that should indicate the number of bytes of its own
- arguments that a function pops on returning, or 0 if the function
- pops no arguments and the caller must therefore pop them all after
- the function returns.
-
- FUNDECL is a C variable whose value is a tree node that describes
- the function in question. Normally it is a node of type
- `FUNCTION_DECL' that describes the declaration of the function.
- From this you can obtain the `DECL_ATTRIBUTES' of the function.
-
- FUNTYPE is a C variable whose value is a tree node that describes
- the function in question. Normally it is a node of type
- `FUNCTION_TYPE' that describes the data type of the function.
- From this it is possible to obtain the data types of the value and
- arguments (if known).
-
- When a call to a library function is being considered, FUNDECL
- will contain an identifier node for the library function. Thus, if
- you need to distinguish among various library functions, you can
- do so by their names. Note that "library function" in this
- context means a function used to perform arithmetic, whose name is
- known specially in the compiler and was not mentioned in the C
- code being compiled.
-
- STACK-SIZE is the number of bytes of arguments passed on the
- stack. If a variable number of bytes is passed, it is zero, and
- argument popping will always be the responsibility of the calling
- function.
-
- On the VAX, all functions always pop their arguments, so the
- definition of this macro is STACK-SIZE. On the 68000, using the
- standard calling convention, no functions pop their arguments, so
- the value of the macro is always 0 in this case. But an
- alternative calling convention is available in which functions
- that take a fixed number of arguments pop them but other functions
- (such as `printf') pop nothing (the caller pops all). When this
- convention is in use, FUNTYPE is examined to determine whether a
- function takes a fixed number of arguments.
-
-`CALL_POPS_ARGS (CUM)'
- A C expression that should indicate the number of bytes a call
- sequence pops off the stack. It is added to the value of
- `RETURN_POPS_ARGS' when compiling a function call.
-
- CUM is the variable in which all arguments to the called function
- have been accumulated.
-
- On certain architectures, such as the SH5, a call trampoline is
- used that pops certain registers off the stack, depending on the
- arguments that have been passed to the function. Since this is a
- property of the call site, not of the called function,
- `RETURN_POPS_ARGS' is not appropriate.
-
-
-\1f
-File: gccint.info, Node: Register Arguments, Next: Scalar Return, Prev: Stack Arguments, Up: Stack and Calling
-
-Passing Arguments in Registers
-------------------------------
-
- This section describes the macros which let you control how various
-types of arguments are passed in registers or how they are arranged in
-the stack.
-
-`FUNCTION_ARG (CUM, MODE, TYPE, NAMED)'
- A C expression that controls whether a function argument is passed
- in a register, and which register.
-
- The arguments are CUM, which summarizes all the previous
- arguments; MODE, the machine mode of the argument; TYPE, the data
- type of the argument as a tree node or 0 if that is not known
- (which happens for C support library functions); and NAMED, which
- is 1 for an ordinary argument and 0 for nameless arguments that
- correspond to `...' in the called function's prototype. TYPE can
- be an incomplete type if a syntax error has previously occurred.
-
- The value of the expression is usually either a `reg' RTX for the
- hard register in which to pass the argument, or zero to pass the
- argument on the stack.
-
- For machines like the VAX and 68000, where normally all arguments
- are pushed, zero suffices as a definition.
-
- The value of the expression can also be a `parallel' RTX. This is
- used when an argument is passed in multiple locations. The mode
- of the of the `parallel' should be the mode of the entire
- argument. The `parallel' holds any number of `expr_list' pairs;
- each one describes where part of the argument is passed. In each
- `expr_list' the first operand must be a `reg' RTX for the hard
- register in which to pass this part of the argument, and the mode
- of the register RTX indicates how large this part of the argument
- is. The second operand of the `expr_list' is a `const_int' which
- gives the offset in bytes into the entire argument of where this
- part starts. As a special exception the first `expr_list' in the
- `parallel' RTX may have a first operand of zero. This indicates
- that the entire argument is also stored on the stack.
-
- The last time this macro is called, it is called with `MODE ==
- VOIDmode', and its result is passed to the `call' or `call_value'
- pattern as operands 2 and 3 respectively.
-
- The usual way to make the ISO library `stdarg.h' work on a machine
- where some arguments are usually passed in registers, is to cause
- nameless arguments to be passed on the stack instead. This is done
- by making `FUNCTION_ARG' return 0 whenever NAMED is 0.
-
- You may use the macro `MUST_PASS_IN_STACK (MODE, TYPE)' in the
- definition of this macro to determine if this argument is of a
- type that must be passed in the stack. If `REG_PARM_STACK_SPACE'
- is not defined and `FUNCTION_ARG' returns nonzero for such an
- argument, the compiler will abort. If `REG_PARM_STACK_SPACE' is
- defined, the argument will be computed in the stack and then
- loaded into a register.
-
-`MUST_PASS_IN_STACK (MODE, TYPE)'
- Define as a C expression that evaluates to nonzero if we do not
- know how to pass TYPE solely in registers. The file `expr.h'
- defines a definition that is usually appropriate, refer to
- `expr.h' for additional documentation.
-
-`FUNCTION_INCOMING_ARG (CUM, MODE, TYPE, NAMED)'
- Define this macro if the target machine has "register windows", so
- that the register in which a function sees an arguments is not
- necessarily the same as the one in which the caller passed the
- argument.
-
- For such machines, `FUNCTION_ARG' computes the register in which
- the caller passes the value, and `FUNCTION_INCOMING_ARG' should be
- defined in a similar fashion to tell the function being called
- where the arguments will arrive.
-
- If `FUNCTION_INCOMING_ARG' is not defined, `FUNCTION_ARG' serves
- both purposes.
-
-`FUNCTION_ARG_PARTIAL_NREGS (CUM, MODE, TYPE, NAMED)'
- A C expression for the number of words, at the beginning of an
- argument, that must be put in registers. The value must be zero
- for arguments that are passed entirely in registers or that are
- entirely pushed on the stack.
-
- On some machines, certain arguments must be passed partially in
- registers and partially in memory. On these machines, typically
- the first N words of arguments are passed in registers, and the
- rest on the stack. If a multi-word argument (a `double' or a
- structure) crosses that boundary, its first few words must be
- passed in registers and the rest must be pushed. This macro tells
- the compiler when this occurs, and how many of the words should go
- in registers.
-
- `FUNCTION_ARG' for these arguments should return the first
- register to be used by the caller for this argument; likewise
- `FUNCTION_INCOMING_ARG', for the called function.
-
-`FUNCTION_ARG_PASS_BY_REFERENCE (CUM, MODE, TYPE, NAMED)'
- A C expression that indicates when an argument must be passed by
- reference. If nonzero for an argument, a copy of that argument is
- made in memory and a pointer to the argument is passed instead of
- the argument itself. The pointer is passed in whatever way is
- appropriate for passing a pointer to that type.
-
- On machines where `REG_PARM_STACK_SPACE' is not defined, a suitable
- definition of this macro might be
- #define FUNCTION_ARG_PASS_BY_REFERENCE\
- (CUM, MODE, TYPE, NAMED) \
- MUST_PASS_IN_STACK (MODE, TYPE)
-
-`FUNCTION_ARG_CALLEE_COPIES (CUM, MODE, TYPE, NAMED)'
- If defined, a C expression that indicates when it is the called
- function's responsibility to make a copy of arguments passed by
- invisible reference. Normally, the caller makes a copy and passes
- the address of the copy to the routine being called. When
- `FUNCTION_ARG_CALLEE_COPIES' is defined and is nonzero, the caller
- does not make a copy. Instead, it passes a pointer to the "live"
- value. The called function must not modify this value. If it can
- be determined that the value won't be modified, it need not make a
- copy; otherwise a copy must be made.
-
-`FUNCTION_ARG_REG_LITTLE_ENDIAN'
- If defined TRUE on a big-endian system then structure arguments
- passed (and returned) in registers are passed in a little-endian
- manner instead of the big-endian manner. On the HP-UX IA64 and
- PA64 platforms structures are aligned differently then integral
- values and setting this value to true will allow for the special
- handling of structure arguments and return values.
-
-`CUMULATIVE_ARGS'
- A C type for declaring a variable that is used as the first
- argument of `FUNCTION_ARG' and other related values. For some
- target machines, the type `int' suffices and can hold the number
- of bytes of argument so far.
-
- There is no need to record in `CUMULATIVE_ARGS' anything about the
- arguments that have been passed on the stack. The compiler has
- other variables to keep track of that. For target machines on
- which all arguments are passed on the stack, there is no need to
- store anything in `CUMULATIVE_ARGS'; however, the data structure
- must exist and should not be empty, so use `int'.
-
-`INIT_CUMULATIVE_ARGS (CUM, FNTYPE, LIBNAME, INDIRECT)'
- A C statement (sans semicolon) for initializing the variable CUM
- for the state at the beginning of the argument list. The variable
- has type `CUMULATIVE_ARGS'. The value of FNTYPE is the tree node
- for the data type of the function which will receive the args, or 0
- if the args are to a compiler support library function. The value
- of INDIRECT is nonzero when processing an indirect call, for
- example a call through a function pointer. The value of INDIRECT
- is zero for a call to an explicitly named function, a library
- function call, or when `INIT_CUMULATIVE_ARGS' is used to find
- arguments for the function being compiled.
-
- When processing a call to a compiler support library function,
- LIBNAME identifies which one. It is a `symbol_ref' rtx which
- contains the name of the function, as a string. LIBNAME is 0 when
- an ordinary C function call is being processed. Thus, each time
- this macro is called, either LIBNAME or FNTYPE is nonzero, but
- never both of them at once.
-
-`INIT_CUMULATIVE_LIBCALL_ARGS (CUM, MODE, LIBNAME)'
- Like `INIT_CUMULATIVE_ARGS' but only used for outgoing libcalls,
- it gets a `MODE' argument instead of FNTYPE, that would be `NULL'.
- INDIRECT would always be zero, too. If this macro is not
- defined, `INIT_CUMULATIVE_ARGS (cum, NULL_RTX, libname, 0)' is
- used instead.
-
-`INIT_CUMULATIVE_INCOMING_ARGS (CUM, FNTYPE, LIBNAME)'
- Like `INIT_CUMULATIVE_ARGS' but overrides it for the purposes of
- finding the arguments for the function being compiled. If this
- macro is undefined, `INIT_CUMULATIVE_ARGS' is used instead.
-
- The value passed for LIBNAME is always 0, since library routines
- with special calling conventions are never compiled with GCC. The
- argument LIBNAME exists for symmetry with `INIT_CUMULATIVE_ARGS'.
-
-`FUNCTION_ARG_ADVANCE (CUM, MODE, TYPE, NAMED)'
- A C statement (sans semicolon) to update the summarizer variable
- CUM to advance past an argument in the argument list. The values
- MODE, TYPE and NAMED describe that argument. Once this is done,
- the variable CUM is suitable for analyzing the _following_
- argument with `FUNCTION_ARG', etc.
-
- This macro need not do anything if the argument in question was
- passed on the stack. The compiler knows how to track the amount
- of stack space used for arguments without any special help.
-
-`FUNCTION_ARG_PADDING (MODE, TYPE)'
- If defined, a C expression which determines whether, and in which
- direction, to pad out an argument with extra space. The value
- should be of type `enum direction': either `upward' to pad above
- the argument, `downward' to pad below, or `none' to inhibit
- padding.
-
- The _amount_ of padding is always just enough to reach the next
- multiple of `FUNCTION_ARG_BOUNDARY'; this macro does not control
- it.
-
- This macro has a default definition which is right for most
- systems. For little-endian machines, the default is to pad
- upward. For big-endian machines, the default is to pad downward
- for an argument of constant size shorter than an `int', and upward
- otherwise.
-
-`PAD_VARARGS_DOWN'
- If defined, a C expression which determines whether the default
- implementation of va_arg will attempt to pad down before reading
- the next argument, if that argument is smaller than its aligned
- space as controlled by `PARM_BOUNDARY'. If this macro is not
- defined, all such arguments are padded down if `BYTES_BIG_ENDIAN'
- is true.
-
-`FUNCTION_ARG_BOUNDARY (MODE, TYPE)'
- If defined, a C expression that gives the alignment boundary, in
- bits, of an argument with the specified mode and type. If it is
- not defined, `PARM_BOUNDARY' is used for all arguments.
-
-`FUNCTION_ARG_REGNO_P (REGNO)'
- A C expression that is nonzero if REGNO is the number of a hard
- register in which function arguments are sometimes passed. This
- does _not_ include implicit arguments such as the static chain and
- the structure-value address. On many machines, no registers can be
- used for this purpose since all function arguments are pushed on
- the stack.
-
-`LOAD_ARGS_REVERSED'
- If defined, the order in which arguments are loaded into their
- respective argument registers is reversed so that the last
- argument is loaded first. This macro only affects arguments
- passed in registers.
-
-
-\1f
-File: gccint.info, Node: Scalar Return, Next: Aggregate Return, Prev: Register Arguments, Up: Stack and Calling
-
-How Scalar Function Values Are Returned
----------------------------------------
-
- This section discusses the macros that control returning scalars as
-values--values that can fit in registers.
-
-`TRADITIONAL_RETURN_FLOAT'
- Define this macro if `-traditional' should not cause functions
- declared to return `float' to convert the value to `double'.
-
-`FUNCTION_VALUE (VALTYPE, FUNC)'
- A C expression to create an RTX representing the place where a
- function returns a value of data type VALTYPE. VALTYPE is a tree
- node representing a data type. Write `TYPE_MODE (VALTYPE)' to get
- the machine mode used to represent that type. On many machines,
- only the mode is relevant. (Actually, on most machines, scalar
- values are returned in the same place regardless of mode).
-
- The value of the expression is usually a `reg' RTX for the hard
- register where the return value is stored. The value can also be a
- `parallel' RTX, if the return value is in multiple places. See
- `FUNCTION_ARG' for an explanation of the `parallel' form.
-
- If `PROMOTE_FUNCTION_RETURN' is defined, you must apply the same
- promotion rules specified in `PROMOTE_MODE' if VALTYPE is a scalar
- type.
-
- If the precise function being called is known, FUNC is a tree node
- (`FUNCTION_DECL') for it; otherwise, FUNC is a null pointer. This
- makes it possible to use a different value-returning convention
- for specific functions when all their calls are known.
-
- `FUNCTION_VALUE' is not used for return vales with aggregate data
- types, because these are returned in another way. See
- `STRUCT_VALUE_REGNUM' and related macros, below.
-
-`FUNCTION_OUTGOING_VALUE (VALTYPE, FUNC)'
- Define this macro if the target machine has "register windows" so
- that the register in which a function returns its value is not the
- same as the one in which the caller sees the value.
-
- For such machines, `FUNCTION_VALUE' computes the register in which
- the caller will see the value. `FUNCTION_OUTGOING_VALUE' should be
- defined in a similar fashion to tell the function where to put the
- value.
-
- If `FUNCTION_OUTGOING_VALUE' is not defined, `FUNCTION_VALUE'
- serves both purposes.
-
- `FUNCTION_OUTGOING_VALUE' is not used for return vales with
- aggregate data types, because these are returned in another way.
- See `STRUCT_VALUE_REGNUM' and related macros, below.
-
-`LIBCALL_VALUE (MODE)'
- A C expression to create an RTX representing the place where a
- library function returns a value of mode MODE. If the precise
- function being called is known, FUNC is a tree node
- (`FUNCTION_DECL') for it; otherwise, FUNC is a null pointer. This
- makes it possible to use a different value-returning convention
- for specific functions when all their calls are known.
-
- Note that "library function" in this context means a compiler
- support routine, used to perform arithmetic, whose name is known
- specially by the compiler and was not mentioned in the C code being
- compiled.
-
- The definition of `LIBRARY_VALUE' need not be concerned aggregate
- data types, because none of the library functions returns such
- types.
-
-`FUNCTION_VALUE_REGNO_P (REGNO)'
- A C expression that is nonzero if REGNO is the number of a hard
- register in which the values of called function may come back.
-
- A register whose use for returning values is limited to serving as
- the second of a pair (for a value of type `double', say) need not
- be recognized by this macro. So for most machines, this definition
- suffices:
-
- #define FUNCTION_VALUE_REGNO_P(N) ((N) == 0)
-
- If the machine has register windows, so that the caller and the
- called function use different registers for the return value, this
- macro should recognize only the caller's register numbers.
-
-`APPLY_RESULT_SIZE'
- Define this macro if `untyped_call' and `untyped_return' need more
- space than is implied by `FUNCTION_VALUE_REGNO_P' for saving and
- restoring an arbitrary return value.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Aggregate Return, Next: Caller Saves, Prev: Scalar Return, Up: Stack and Calling
-
-How Large Values Are Returned
------------------------------
-
- When a function value's mode is `BLKmode' (and in some other cases),
-the value is not returned according to `FUNCTION_VALUE' (*note Scalar
-Return::). Instead, the caller passes the address of a block of memory
-in which the value should be stored. This address is called the
-"structure value address".
-
- This section describes how to control returning structure values in
-memory.
-
-`RETURN_IN_MEMORY (TYPE)'
- A C expression which can inhibit the returning of certain function
- values in registers, based on the type of value. A nonzero value
- says to return the function value in memory, just as large
- structures are always returned. Here TYPE will be a C expression
- of type `tree', representing the data type of the value.
-
- Note that values of mode `BLKmode' must be explicitly handled by
- this macro. Also, the option `-fpcc-struct-return' takes effect
- regardless of this macro. On most systems, it is possible to
- leave the macro undefined; this causes a default definition to be
- used, whose value is the constant 1 for `BLKmode' values, and 0
- otherwise.
-
- Do not use this macro to indicate that structures and unions
- should always be returned in memory. You should instead use
- `DEFAULT_PCC_STRUCT_RETURN' to indicate this.
-
-`DEFAULT_PCC_STRUCT_RETURN'
- Define this macro to be 1 if all structure and union return values
- must be in memory. Since this results in slower code, this should
- be defined only if needed for compatibility with other compilers
- or with an ABI. If you define this macro to be 0, then the
- conventions used for structure and union return values are decided
- by the `RETURN_IN_MEMORY' macro.
-
- If not defined, this defaults to the value 1.
-
-`STRUCT_VALUE_REGNUM'
- If the structure value address is passed in a register, then
- `STRUCT_VALUE_REGNUM' should be the number of that register.
-
-`STRUCT_VALUE'
- If the structure value address is not passed in a register, define
- `STRUCT_VALUE' as an expression returning an RTX for the place
- where the address is passed. If it returns 0, the address is
- passed as an "invisible" first argument.
-
-`STRUCT_VALUE_INCOMING_REGNUM'
- On some architectures the place where the structure value address
- is found by the called function is not the same place that the
- caller put it. This can be due to register windows, or it could
- be because the function prologue moves it to a different place.
-
- If the incoming location of the structure value address is in a
- register, define this macro as the register number.
-
-`STRUCT_VALUE_INCOMING'
- If the incoming location is not a register, then you should define
- `STRUCT_VALUE_INCOMING' as an expression for an RTX for where the
- called function should find the value. If it should find the
- value on the stack, define this to create a `mem' which refers to
- the frame pointer. A definition of 0 means that the address is
- passed as an "invisible" first argument.
-
-`PCC_STATIC_STRUCT_RETURN'
- Define this macro if the usual system convention on the target
- machine for returning structures and unions is for the called
- function to return the address of a static variable containing the
- value.
-
- Do not define this if the usual system convention is for the
- caller to pass an address to the subroutine.
-
- This macro has effect in `-fpcc-struct-return' mode, but it does
- nothing when you use `-freg-struct-return' mode.
-
-\1f
-File: gccint.info, Node: Caller Saves, Next: Function Entry, Prev: Aggregate Return, Up: Stack and Calling
-
-Caller-Saves Register Allocation
---------------------------------
-
- If you enable it, GCC can save registers around function calls. This
-makes it possible to use call-clobbered registers to hold variables that
-must live across calls.
-
-`DEFAULT_CALLER_SAVES'
- Define this macro if function calls on the target machine do not
- preserve any registers; in other words, if `CALL_USED_REGISTERS'
- has 1 for all registers. When defined, this macro enables
- `-fcaller-saves' by default for all optimization levels. It has
- no effect for optimization levels 2 and higher, where
- `-fcaller-saves' is the default.
-
-`CALLER_SAVE_PROFITABLE (REFS, CALLS)'
- A C expression to determine whether it is worthwhile to consider
- placing a pseudo-register in a call-clobbered hard register and
- saving and restoring it around each function call. The expression
- should be 1 when this is worth doing, and 0 otherwise.
-
- If you don't define this macro, a default is used which is good on
- most machines: `4 * CALLS < REFS'.
-
-`HARD_REGNO_CALLER_SAVE_MODE (REGNO, NREGS)'
- A C expression specifying which mode is required for saving NREGS
- of a pseudo-register in call-clobbered hard register REGNO. If
- REGNO is unsuitable for caller save, `VOIDmode' should be
- returned. For most machines this macro need not be defined since
- GCC will select the smallest suitable mode.
-
-\1f
-File: gccint.info, Node: Function Entry, Next: Profiling, Prev: Caller Saves, Up: Stack and Calling
-
-Function Entry and Exit
------------------------
-
- This section describes the macros that output function entry
-("prologue") and exit ("epilogue") code.
-
- - Target Hook: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *FILE,
- HOST_WIDE_INT SIZE)
- If defined, a function that outputs the assembler code for entry
- to a function. The prologue is responsible for setting up the
- stack frame, initializing the frame pointer register, saving
- registers that must be saved, and allocating SIZE additional bytes
- of storage for the local variables. SIZE is an integer. FILE is
- a stdio stream to which the assembler code should be output.
-
- The label for the beginning of the function need not be output by
- this macro. That has already been done when the macro is run.
-
- To determine which registers to save, the macro can refer to the
- array `regs_ever_live': element R is nonzero if hard register R is
- used anywhere within the function. This implies the function
- prologue should save register R, provided it is not one of the
- call-used registers. (`TARGET_ASM_FUNCTION_EPILOGUE' must
- likewise use `regs_ever_live'.)
-
- On machines that have "register windows", the function entry code
- does not save on the stack the registers that are in the windows,
- even if they are supposed to be preserved by function calls;
- instead it takes appropriate steps to "push" the register stack,
- if any non-call-used registers are used in the function.
-
- On machines where functions may or may not have frame-pointers, the
- function entry code must vary accordingly; it must set up the frame
- pointer if one is wanted, and not otherwise. To determine whether
- a frame pointer is in wanted, the macro can refer to the variable
- `frame_pointer_needed'. The variable's value will be 1 at run
- time in a function that needs a frame pointer. *Note
- Elimination::.
-
- The function entry code is responsible for allocating any stack
- space required for the function. This stack space consists of the
- regions listed below. In most cases, these regions are allocated
- in the order listed, with the last listed region closest to the
- top of the stack (the lowest address if `STACK_GROWS_DOWNWARD' is
- defined, and the highest address if it is not defined). You can
- use a different order for a machine if doing so is more convenient
- or required for compatibility reasons. Except in cases where
- required by standard or by a debugger, there is no reason why the
- stack layout used by GCC need agree with that used by other
- compilers for a machine.
-
- - Target Hook: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *FILE)
- If defined, a function that outputs assembler code at the end of a
- prologue. This should be used when the function prologue is being
- emitted as RTL, and you have some extra assembler that needs to be
- emitted. *Note prologue instruction pattern::.
-
- - Target Hook: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *FILE)
- If defined, a function that outputs assembler code at the start of
- an epilogue. This should be used when the function epilogue is
- being emitted as RTL, and you have some extra assembler that needs
- to be emitted. *Note epilogue instruction pattern::.
-
- - Target Hook: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *FILE,
- HOST_WIDE_INT SIZE)
- If defined, a function that outputs the assembler code for exit
- from a function. The epilogue is responsible for restoring the
- saved registers and stack pointer to their values when the
- function was called, and returning control to the caller. This
- macro takes the same arguments as the macro
- `TARGET_ASM_FUNCTION_PROLOGUE', and the registers to restore are
- determined from `regs_ever_live' and `CALL_USED_REGISTERS' in the
- same way.
-
- On some machines, there is a single instruction that does all the
- work of returning from the function. On these machines, give that
- instruction the name `return' and do not define the macro
- `TARGET_ASM_FUNCTION_EPILOGUE' at all.
-
- Do not define a pattern named `return' if you want the
- `TARGET_ASM_FUNCTION_EPILOGUE' to be used. If you want the target
- switches to control whether return instructions or epilogues are
- used, define a `return' pattern with a validity condition that
- tests the target switches appropriately. If the `return'
- pattern's validity condition is false, epilogues will be used.
-
- On machines where functions may or may not have frame-pointers, the
- function exit code must vary accordingly. Sometimes the code for
- these two cases is completely different. To determine whether a
- frame pointer is wanted, the macro can refer to the variable
- `frame_pointer_needed'. The variable's value will be 1 when
- compiling a function that needs a frame pointer.
-
- Normally, `TARGET_ASM_FUNCTION_PROLOGUE' and
- `TARGET_ASM_FUNCTION_EPILOGUE' must treat leaf functions specially.
- The C variable `current_function_is_leaf' is nonzero for such a
- function. *Note Leaf Functions::.
-
- On some machines, some functions pop their arguments on exit while
- others leave that for the caller to do. For example, the 68020
- when given `-mrtd' pops arguments in functions that take a fixed
- number of arguments.
-
- Your definition of the macro `RETURN_POPS_ARGS' decides which
- functions pop their own arguments. `TARGET_ASM_FUNCTION_EPILOGUE'
- needs to know what was decided. The variable that is called
- `current_function_pops_args' is the number of bytes of its
- arguments that a function should pop. *Note Scalar Return::.
-
- * A region of `current_function_pretend_args_size' bytes of
- uninitialized space just underneath the first argument
- arriving on the stack. (This may not be at the very start of
- the allocated stack region if the calling sequence has pushed
- anything else since pushing the stack arguments. But
- usually, on such machines, nothing else has been pushed yet,
- because the function prologue itself does all the pushing.)
- This region is used on machines where an argument may be
- passed partly in registers and partly in memory, and, in some
- cases to support the features in `<varargs.h>' and
- `<stdarg.h>'.
-
- * An area of memory used to save certain registers used by the
- function. The size of this area, which may also include
- space for such things as the return address and pointers to
- previous stack frames, is machine-specific and usually
- depends on which registers have been used in the function.
- Machines with register windows often do not require a save
- area.
-
- * A region of at least SIZE bytes, possibly rounded up to an
- allocation boundary, to contain the local variables of the
- function. On some machines, this region and the save area
- may occur in the opposite order, with the save area closer to
- the top of the stack.
-
- * Optionally, when `ACCUMULATE_OUTGOING_ARGS' is defined, a
- region of `current_function_outgoing_args_size' bytes to be
- used for outgoing argument lists of the function. *Note
- Stack Arguments::.
-
- Normally, it is necessary for the macros
- `TARGET_ASM_FUNCTION_PROLOGUE' and `TARGET_ASM_FUNCTION_EPILOGUE'
- to treat leaf functions specially. The C variable
- `current_function_is_leaf' is nonzero for such a function.
-
-`EXIT_IGNORE_STACK'
- Define this macro as a C expression that is nonzero if the return
- instruction or the function epilogue ignores the value of the stack
- pointer; in other words, if it is safe to delete an instruction to
- adjust the stack pointer before a return from the function.
-
- Note that this macro's value is relevant only for functions for
- which frame pointers are maintained. It is never safe to delete a
- final stack adjustment in a function that has no frame pointer,
- and the compiler knows this regardless of `EXIT_IGNORE_STACK'.
-
-`EPILOGUE_USES (REGNO)'
- Define this macro as a C expression that is nonzero for registers
- that are used by the epilogue or the `return' pattern. The stack
- and frame pointer registers are already be assumed to be used as
- needed.
-
-`EH_USES (REGNO)'
- Define this macro as a C expression that is nonzero for registers
- that are used by the exception handling mechanism, and so should
- be considered live on entry to an exception edge.
-
-`DELAY_SLOTS_FOR_EPILOGUE'
- Define this macro if the function epilogue contains delay slots to
- which instructions from the rest of the function can be "moved".
- The definition should be a C expression whose value is an integer
- representing the number of delay slots there.
-
-`ELIGIBLE_FOR_EPILOGUE_DELAY (INSN, N)'
- A C expression that returns 1 if INSN can be placed in delay slot
- number N of the epilogue.
-
- The argument N is an integer which identifies the delay slot now
- being considered (since different slots may have different rules of
- eligibility). It is never negative and is always less than the
- number of epilogue delay slots (what `DELAY_SLOTS_FOR_EPILOGUE'
- returns). If you reject a particular insn for a given delay slot,
- in principle, it may be reconsidered for a subsequent delay slot.
- Also, other insns may (at least in principle) be considered for
- the so far unfilled delay slot.
-
- The insns accepted to fill the epilogue delay slots are put in an
- RTL list made with `insn_list' objects, stored in the variable
- `current_function_epilogue_delay_list'. The insn for the first
- delay slot comes first in the list. Your definition of the macro
- `TARGET_ASM_FUNCTION_EPILOGUE' should fill the delay slots by
- outputting the insns in this list, usually by calling
- `final_scan_insn'.
-
- You need not define this macro if you did not define
- `DELAY_SLOTS_FOR_EPILOGUE'.
-
-`ASM_OUTPUT_MI_THUNK (FILE, THUNK_FNDECL, DELTA, FUNCTION)'
- A C compound statement that outputs the assembler code for a thunk
- function, used to implement C++ virtual function calls with
- multiple inheritance. The thunk acts as a wrapper around a
- virtual function, adjusting the implicit object parameter before
- handing control off to the real function.
-
- First, emit code to add the integer DELTA to the location that
- contains the incoming first argument. Assume that this argument
- contains a pointer, and is the one used to pass the `this' pointer
- in C++. This is the incoming argument _before_ the function
- prologue, e.g. `%o0' on a sparc. The addition must preserve the
- values of all other incoming arguments.
-
- After the addition, emit code to jump to FUNCTION, which is a
- `FUNCTION_DECL'. This is a direct pure jump, not a call, and does
- not touch the return address. Hence returning from FUNCTION will
- return to whoever called the current `thunk'.
-
- The effect must be as if FUNCTION had been called directly with
- the adjusted first argument. This macro is responsible for
- emitting all of the code for a thunk function;
- `TARGET_ASM_FUNCTION_PROLOGUE' and `TARGET_ASM_FUNCTION_EPILOGUE'
- are not invoked.
-
- The THUNK_FNDECL is redundant. (DELTA and FUNCTION have already
- been extracted from it.) It might possibly be useful on some
- targets, but probably not.
-
- If you do not define this macro, the target-independent code in
- the C++ front end will generate a less efficient heavyweight thunk
- that calls FUNCTION instead of jumping to it. The generic
- approach does not support varargs.
-
-\1f
-File: gccint.info, Node: Profiling, Next: Tail Calls, Prev: Function Entry, Up: Stack and Calling
-
-Generating Code for Profiling
------------------------------
-
- These macros will help you generate code for profiling.
-
-`FUNCTION_PROFILER (FILE, LABELNO)'
- A C statement or compound statement to output to FILE some
- assembler code to call the profiling subroutine `mcount'.
-
- The details of how `mcount' expects to be called are determined by
- your operating system environment, not by GCC. To figure them out,
- compile a small program for profiling using the system's installed
- C compiler and look at the assembler code that results.
-
- Older implementations of `mcount' expect the address of a counter
- variable to be loaded into some register. The name of this
- variable is `LP' followed by the number LABELNO, so you would
- generate the name using `LP%d' in a `fprintf'.
-
-`PROFILE_HOOK'
- A C statement or compound statement to output to FILE some assembly
- code to call the profiling subroutine `mcount' even the target does
- not support profiling.
-
-`NO_PROFILE_COUNTERS'
- Define this macro if the `mcount' subroutine on your system does
- not need a counter variable allocated for each function. This is
- true for almost all modern implementations. If you define this
- macro, you must not use the LABELNO argument to
- `FUNCTION_PROFILER'.
-
-`PROFILE_BEFORE_PROLOGUE'
- Define this macro if the code for function profiling should come
- before the function prologue. Normally, the profiling code comes
- after.
-
-`TARGET_ALLOWS_PROFILING_WITHOUT_FRAME_POINTER'
- On some targets, it is impossible to use profiling when the frame
- pointer has been omitted. For example, on x86 GNU/Linux systems,
- the `mcount' routine provided by the GNU C Library finds the
- address of the routine that called the routine that called `mcount'
- by looking in the immediate caller's stack frame. If the immediate
- caller has no frame pointer, this lookup will fail.
-
- By default, GCC assumes that the target does allow profiling when
- the frame pointer is omitted. This macro should be defined to a C
- expression that evaluates to `false' if the target does not allow
- profiling when the frame pointer is omitted.
-
-
-\1f
-File: gccint.info, Node: Tail Calls, Prev: Profiling, Up: Stack and Calling
-
-Permitting tail calls
----------------------
-
-`FUNCTION_OK_FOR_SIBCALL (DECL)'
- A C expression that evaluates to true if it is ok to perform a
- sibling call to DECL from the current function.
-
- It is not uncommon for limitations of calling conventions to
- prevent tail calls to functions outside the current unit of
- translation, or during PIC compilation. Use this macro to enforce
- these restrictions, as the `sibcall' md pattern can not fail, or
- fall over to a "normal" call.
-
-\1f
-File: gccint.info, Node: Varargs, Next: Trampolines, Prev: Stack and Calling, Up: Target Macros
-
-Implementing the Varargs Macros
-===============================
-
- GCC comes with an implementation of `<varargs.h>' and `<stdarg.h>'
-that work without change on machines that pass arguments on the stack.
-Other machines require their own implementations of varargs, and the
-two machine independent header files must have conditionals to include
-it.
-
- ISO `<stdarg.h>' differs from traditional `<varargs.h>' mainly in
-the calling convention for `va_start'. The traditional implementation
-takes just one argument, which is the variable in which to store the
-argument pointer. The ISO implementation of `va_start' takes an
-additional second argument. The user is supposed to write the last
-named argument of the function here.
-
- However, `va_start' should not use this argument. The way to find
-the end of the named arguments is with the built-in functions described
-below.
-
-`__builtin_saveregs ()'
- Use this built-in function to save the argument registers in
- memory so that the varargs mechanism can access them. Both ISO
- and traditional versions of `va_start' must use
- `__builtin_saveregs', unless you use `SETUP_INCOMING_VARARGS' (see
- below) instead.
-
- On some machines, `__builtin_saveregs' is open-coded under the
- control of the macro `EXPAND_BUILTIN_SAVEREGS'. On other machines,
- it calls a routine written in assembler language, found in
- `libgcc2.c'.
-
- Code generated for the call to `__builtin_saveregs' appears at the
- beginning of the function, as opposed to where the call to
- `__builtin_saveregs' is written, regardless of what the code is.
- This is because the registers must be saved before the function
- starts to use them for its own purposes.
-
-`__builtin_args_info (CATEGORY)'
- Use this built-in function to find the first anonymous arguments in
- registers.
-
- In general, a machine may have several categories of registers
- used for arguments, each for a particular category of data types.
- (For example, on some machines, floating-point registers are used
- for floating-point arguments while other arguments are passed in
- the general registers.) To make non-varargs functions use the
- proper calling convention, you have defined the `CUMULATIVE_ARGS'
- data type to record how many registers in each category have been
- used so far
-
- `__builtin_args_info' accesses the same data structure of type
- `CUMULATIVE_ARGS' after the ordinary argument layout is finished
- with it, with CATEGORY specifying which word to access. Thus, the
- value indicates the first unused register in a given category.
-
- Normally, you would use `__builtin_args_info' in the implementation
- of `va_start', accessing each category just once and storing the
- value in the `va_list' object. This is because `va_list' will
- have to update the values, and there is no way to alter the values
- accessed by `__builtin_args_info'.
-
-`__builtin_next_arg (LASTARG)'
- This is the equivalent of `__builtin_args_info', for stack
- arguments. It returns the address of the first anonymous stack
- argument, as type `void *'. If `ARGS_GROW_DOWNWARD', it returns
- the address of the location above the first anonymous stack
- argument. Use it in `va_start' to initialize the pointer for
- fetching arguments from the stack. Also use it in `va_start' to
- verify that the second parameter LASTARG is the last named argument
- of the current function.
-
-`__builtin_classify_type (OBJECT)'
- Since each machine has its own conventions for which data types are
- passed in which kind of register, your implementation of `va_arg'
- has to embody these conventions. The easiest way to categorize the
- specified data type is to use `__builtin_classify_type' together
- with `sizeof' and `__alignof__'.
-
- `__builtin_classify_type' ignores the value of OBJECT, considering
- only its data type. It returns an integer describing what kind of
- type that is--integer, floating, pointer, structure, and so on.
-
- The file `typeclass.h' defines an enumeration that you can use to
- interpret the values of `__builtin_classify_type'.
-
- These machine description macros help implement varargs:
-
-`EXPAND_BUILTIN_SAVEREGS ()'
- If defined, is a C expression that produces the machine-specific
- code for a call to `__builtin_saveregs'. This code will be moved
- to the very beginning of the function, before any parameter access
- are made. The return value of this function should be an RTX that
- contains the value to use as the return of `__builtin_saveregs'.
-
-`SETUP_INCOMING_VARARGS (ARGS_SO_FAR, MODE, TYPE, PRETEND_ARGS_SIZE, SECOND_TIME)'
- This macro offers an alternative to using `__builtin_saveregs' and
- defining the macro `EXPAND_BUILTIN_SAVEREGS'. Use it to store the
- anonymous register arguments into the stack so that all the
- arguments appear to have been passed consecutively on the stack.
- Once this is done, you can use the standard implementation of
- varargs that works for machines that pass all their arguments on
- the stack.
-
- The argument ARGS_SO_FAR is the `CUMULATIVE_ARGS' data structure,
- containing the values that are obtained after processing the named
- arguments. The arguments MODE and TYPE describe the last named
- argument--its machine mode and its data type as a tree node.
-
- The macro implementation should do two things: first, push onto the
- stack all the argument registers _not_ used for the named
- arguments, and second, store the size of the data thus pushed into
- the `int'-valued variable whose name is supplied as the argument
- PRETEND_ARGS_SIZE. The value that you store here will serve as
- additional offset for setting up the stack frame.
-
- Because you must generate code to push the anonymous arguments at
- compile time without knowing their data types,
- `SETUP_INCOMING_VARARGS' is only useful on machines that have just
- a single category of argument register and use it uniformly for
- all data types.
-
- If the argument SECOND_TIME is nonzero, it means that the
- arguments of the function are being analyzed for the second time.
- This happens for an inline function, which is not actually
- compiled until the end of the source file. The macro
- `SETUP_INCOMING_VARARGS' should not generate any instructions in
- this case.
-
-`STRICT_ARGUMENT_NAMING'
- Define this macro to be a nonzero value if the location where a
- function argument is passed depends on whether or not it is a
- named argument.
-
- This macro controls how the NAMED argument to `FUNCTION_ARG' is
- set for varargs and stdarg functions. If this macro returns a
- nonzero value, the NAMED argument is always true for named
- arguments, and false for unnamed arguments. If it returns a value
- of zero, but `SETUP_INCOMING_VARARGS' is defined, then all
- arguments are treated as named. Otherwise, all named arguments
- except the last are treated as named.
-
- You need not define this macro if it always returns zero.
-
-`PRETEND_OUTGOING_VARARGS_NAMED'
- If you need to conditionally change ABIs so that one works with
- `SETUP_INCOMING_VARARGS', but the other works like neither
- `SETUP_INCOMING_VARARGS' nor `STRICT_ARGUMENT_NAMING' was defined,
- then define this macro to return nonzero if
- `SETUP_INCOMING_VARARGS' is used, zero otherwise. Otherwise, you
- should not define this macro.
-
-\1f
-File: gccint.info, Node: Trampolines, Next: Library Calls, Prev: Varargs, Up: Target Macros
-
-Trampolines for Nested Functions
-================================
-
- A "trampoline" is a small piece of code that is created at run time
-when the address of a nested function is taken. It normally resides on
-the stack, in the stack frame of the containing function. These macros
-tell GCC how to generate code to allocate and initialize a trampoline.
-
- The instructions in the trampoline must do two things: load a
-constant address into the static chain register, and jump to the real
-address of the nested function. On CISC machines such as the m68k,
-this requires two instructions, a move immediate and a jump. Then the
-two addresses exist in the trampoline as word-long immediate operands.
-On RISC machines, it is often necessary to load each address into a
-register in two parts. Then pieces of each address form separate
-immediate operands.
-
- The code generated to initialize the trampoline must store the
-variable parts--the static chain value and the function address--into
-the immediate operands of the instructions. On a CISC machine, this is
-simply a matter of copying each address to a memory reference at the
-proper offset from the start of the trampoline. On a RISC machine, it
-may be necessary to take out pieces of the address and store them
-separately.
-
-`TRAMPOLINE_TEMPLATE (FILE)'
- A C statement to output, on the stream FILE, assembler code for a
- block of data that contains the constant parts of a trampoline.
- This code should not include a label--the label is taken care of
- automatically.
-
- If you do not define this macro, it means no template is needed
- for the target. Do not define this macro on systems where the
- block move code to copy the trampoline into place would be larger
- than the code to generate it on the spot.
-
-`TRAMPOLINE_SECTION'
- The name of a subroutine to switch to the section in which the
- trampoline template is to be placed (*note Sections::). The
- default is a value of `readonly_data_section', which places the
- trampoline in the section containing read-only data.
-
-`TRAMPOLINE_SIZE'
- A C expression for the size in bytes of the trampoline, as an
- integer.
-
-`TRAMPOLINE_ALIGNMENT'
- Alignment required for trampolines, in bits.
-
- If you don't define this macro, the value of `BIGGEST_ALIGNMENT'
- is used for aligning trampolines.
-
-`INITIALIZE_TRAMPOLINE (ADDR, FNADDR, STATIC_CHAIN)'
- A C statement to initialize the variable parts of a trampoline.
- ADDR is an RTX for the address of the trampoline; FNADDR is an RTX
- for the address of the nested function; STATIC_CHAIN is an RTX for
- the static chain value that should be passed to the function when
- it is called.
-
-`TRAMPOLINE_ADJUST_ADDRESS (ADDR)'
- A C statement that should perform any machine-specific adjustment
- in the address of the trampoline. Its argument contains the
- address that was passed to `INITIALIZE_TRAMPOLINE'. In case the
- address to be used for a function call should be different from
- the address in which the template was stored, the different
- address should be assigned to ADDR. If this macro is not defined,
- ADDR will be used for function calls.
-
-`ALLOCATE_TRAMPOLINE (FP)'
- A C expression to allocate run-time space for a trampoline. The
- expression value should be an RTX representing a memory reference
- to the space for the trampoline.
-
- If this macro is not defined, by default the trampoline is
- allocated as a stack slot. This default is right for most
- machines. The exceptions are machines where it is impossible to
- execute instructions in the stack area. On such machines, you may
- have to implement a separate stack, using this macro in
- conjunction with `TARGET_ASM_FUNCTION_PROLOGUE' and
- `TARGET_ASM_FUNCTION_EPILOGUE'.
-
- FP points to a data structure, a `struct function', which
- describes the compilation status of the immediate containing
- function of the function which the trampoline is for. Normally
- (when `ALLOCATE_TRAMPOLINE' is not defined), the stack slot for the
- trampoline is in the stack frame of this containing function.
- Other allocation strategies probably must do something analogous
- with this information.
-
- Implementing trampolines is difficult on many machines because they
-have separate instruction and data caches. Writing into a stack
-location fails to clear the memory in the instruction cache, so when
-the program jumps to that location, it executes the old contents.
-
- Here are two possible solutions. One is to clear the relevant parts
-of the instruction cache whenever a trampoline is set up. The other is
-to make all trampolines identical, by having them jump to a standard
-subroutine. The former technique makes trampoline execution faster; the
-latter makes initialization faster.
-
- To clear the instruction cache when a trampoline is initialized,
-define the following macros which describe the shape of the cache.
-
-`INSN_CACHE_SIZE'
- The total size in bytes of the cache.
-
-`INSN_CACHE_LINE_WIDTH'
- The length in bytes of each cache line. The cache is divided into
- cache lines which are disjoint slots, each holding a contiguous
- chunk of data fetched from memory. Each time data is brought into
- the cache, an entire line is read at once. The data loaded into a
- cache line is always aligned on a boundary equal to the line size.
-
-`INSN_CACHE_DEPTH'
- The number of alternative cache lines that can hold any particular
- memory location.
-
- Alternatively, if the machine has system calls or instructions to
-clear the instruction cache directly, you can define the following
-macro.
-
-`CLEAR_INSN_CACHE (BEG, END)'
- If defined, expands to a C expression clearing the _instruction
- cache_ in the specified interval. If it is not defined, and the
- macro `INSN_CACHE_SIZE' is defined, some generic code is generated
- to clear the cache. The definition of this macro would typically
- be a series of `asm' statements. Both BEG and END are both pointer
- expressions.
-
- To use a standard subroutine, define the following macro. In
-addition, you must make sure that the instructions in a trampoline fill
-an entire cache line with identical instructions, or else ensure that
-the beginning of the trampoline code is always aligned at the same
-point in its cache line. Look in `m68k.h' as a guide.
-
-`TRANSFER_FROM_TRAMPOLINE'
- Define this macro if trampolines need a special subroutine to do
- their work. The macro should expand to a series of `asm'
- statements which will be compiled with GCC. They go in a library
- function named `__transfer_from_trampoline'.
-
- If you need to avoid executing the ordinary prologue code of a
- compiled C function when you jump to the subroutine, you can do so
- by placing a special label of your own in the assembler code. Use
- one `asm' statement to generate an assembler label, and another to
- make the label global. Then trampolines can use that label to
- jump directly to your special assembler code.
-
-\1f
-File: gccint.info, Node: Library Calls, Next: Addressing Modes, Prev: Trampolines, Up: Target Macros
-
-Implicit Calls to Library Routines
-==================================
-
- Here is an explanation of implicit calls to library routines.
-
-`MULSI3_LIBCALL'
- A C string constant giving the name of the function to call for
- multiplication of one signed full-word by another. If you do not
- define this macro, the default name is used, which is `__mulsi3',
- a function defined in `libgcc.a'.
-
-`DIVSI3_LIBCALL'
- A C string constant giving the name of the function to call for
- division of one signed full-word by another. If you do not define
- this macro, the default name is used, which is `__divsi3', a
- function defined in `libgcc.a'.
-
-`UDIVSI3_LIBCALL'
- A C string constant giving the name of the function to call for
- division of one unsigned full-word by another. If you do not
- define this macro, the default name is used, which is `__udivsi3',
- a function defined in `libgcc.a'.
-
-`MODSI3_LIBCALL'
- A C string constant giving the name of the function to call for the
- remainder in division of one signed full-word by another. If you
- do not define this macro, the default name is used, which is
- `__modsi3', a function defined in `libgcc.a'.
-
-`UMODSI3_LIBCALL'
- A C string constant giving the name of the function to call for the
- remainder in division of one unsigned full-word by another. If
- you do not define this macro, the default name is used, which is
- `__umodsi3', a function defined in `libgcc.a'.
-
-`MULDI3_LIBCALL'
- A C string constant giving the name of the function to call for
- multiplication of one signed double-word by another. If you do not
- define this macro, the default name is used, which is `__muldi3',
- a function defined in `libgcc.a'.
-
-`DIVDI3_LIBCALL'
- A C string constant giving the name of the function to call for
- division of one signed double-word by another. If you do not
- define this macro, the default name is used, which is `__divdi3', a
- function defined in `libgcc.a'.
-
-`UDIVDI3_LIBCALL'
- A C string constant giving the name of the function to call for
- division of one unsigned full-word by another. If you do not
- define this macro, the default name is used, which is `__udivdi3',
- a function defined in `libgcc.a'.
-
-`MODDI3_LIBCALL'
- A C string constant giving the name of the function to call for the
- remainder in division of one signed double-word by another. If
- you do not define this macro, the default name is used, which is
- `__moddi3', a function defined in `libgcc.a'.
-
-`UMODDI3_LIBCALL'
- A C string constant giving the name of the function to call for the
- remainder in division of one unsigned full-word by another. If
- you do not define this macro, the default name is used, which is
- `__umoddi3', a function defined in `libgcc.a'.
-
-`INIT_TARGET_OPTABS'
- Define this macro as a C statement that declares additional library
- routines renames existing ones. `init_optabs' calls this macro
- after initializing all the normal library routines.
-
-`FLOAT_LIB_COMPARE_RETURNS_BOOL'
- Define this macro as a C statement that returns nonzero if a call
- to the floating point comparison library function will return a
- boolean value that indicates the result of the comparison. It
- should return zero if one of gcc's own libgcc functions is called.
-
- Most ports don't need to define this macro.
-
-`TARGET_EDOM'
- The value of `EDOM' on the target machine, as a C integer constant
- expression. If you don't define this macro, GCC does not attempt
- to deposit the value of `EDOM' into `errno' directly. Look in
- `/usr/include/errno.h' to find the value of `EDOM' on your system.
-
- If you do not define `TARGET_EDOM', then compiled code reports
- domain errors by calling the library function and letting it
- report the error. If mathematical functions on your system use
- `matherr' when there is an error, then you should leave
- `TARGET_EDOM' undefined so that `matherr' is used normally.
-
-`GEN_ERRNO_RTX'
- Define this macro as a C expression to create an rtl expression
- that refers to the global "variable" `errno'. (On certain systems,
- `errno' may not actually be a variable.) If you don't define this
- macro, a reasonable default is used.
-
-`TARGET_MEM_FUNCTIONS'
- Define this macro if GCC should generate calls to the ISO C (and
- System V) library functions `memcpy', `memmove' and `memset'
- rather than the BSD functions `bcopy' and `bzero'.
-
-`LIBGCC_NEEDS_DOUBLE'
- Define this macro if `float' arguments cannot be passed to library
- routines (so they must be converted to `double'). This macro
- affects both how library calls are generated and how the library
- routines in `libgcc.a' accept their arguments. It is useful on
- machines where floating and fixed point arguments are passed
- differently, such as the i860.
-
-`NEXT_OBJC_RUNTIME'
- Define this macro to generate code for Objective-C message sending
- using the calling convention of the NeXT system. This calling
- convention involves passing the object, the selector and the
- method arguments all at once to the method-lookup library function.
-
- The default calling convention passes just the object and the
- selector to the lookup function, which returns a pointer to the
- method.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Addressing Modes, Next: Condition Code, Prev: Library Calls, Up: Target Macros
-
-Addressing Modes
-================
-
- This is about addressing modes.
-
-`HAVE_PRE_INCREMENT'
-`HAVE_PRE_DECREMENT'
-`HAVE_POST_INCREMENT'
-`HAVE_POST_DECREMENT'
- A C expression that is nonzero if the machine supports
- pre-increment, pre-decrement, post-increment, or post-decrement
- addressing respectively.
-
-`HAVE_PRE_MODIFY_DISP'
-`HAVE_POST_MODIFY_DISP'
- A C expression that is nonzero if the machine supports pre- or
- post-address side-effect generation involving constants other than
- the size of the memory operand.
-
-`HAVE_PRE_MODIFY_REG'
-`HAVE_POST_MODIFY_REG'
- A C expression that is nonzero if the machine supports pre- or
- post-address side-effect generation involving a register
- displacement.
-
-`CONSTANT_ADDRESS_P (X)'
- A C expression that is 1 if the RTX X is a constant which is a
- valid address. On most machines, this can be defined as
- `CONSTANT_P (X)', but a few machines are more restrictive in which
- constant addresses are supported.
-
- `CONSTANT_P' accepts integer-values expressions whose values are
- not explicitly known, such as `symbol_ref', `label_ref', and
- `high' expressions and `const' arithmetic expressions, in addition
- to `const_int' and `const_double' expressions.
-
-`MAX_REGS_PER_ADDRESS'
- A number, the maximum number of registers that can appear in a
- valid memory address. Note that it is up to you to specify a
- value equal to the maximum number that `GO_IF_LEGITIMATE_ADDRESS'
- would ever accept.
-
-`GO_IF_LEGITIMATE_ADDRESS (MODE, X, LABEL)'
- A C compound statement with a conditional `goto LABEL;' executed
- if X (an RTX) is a legitimate memory address on the target machine
- for a memory operand of mode MODE.
-
- It usually pays to define several simpler macros to serve as
- subroutines for this one. Otherwise it may be too complicated to
- understand.
-
- This macro must exist in two variants: a strict variant and a
- non-strict one. The strict variant is used in the reload pass. It
- must be defined so that any pseudo-register that has not been
- allocated a hard register is considered a memory reference. In
- contexts where some kind of register is required, a pseudo-register
- with no hard register must be rejected.
-
- The non-strict variant is used in other passes. It must be
- defined to accept all pseudo-registers in every context where some
- kind of register is required.
-
- Compiler source files that want to use the strict variant of this
- macro define the macro `REG_OK_STRICT'. You should use an `#ifdef
- REG_OK_STRICT' conditional to define the strict variant in that
- case and the non-strict variant otherwise.
-
- Subroutines to check for acceptable registers for various purposes
- (one for base registers, one for index registers, and so on) are
- typically among the subroutines used to define
- `GO_IF_LEGITIMATE_ADDRESS'. Then only these subroutine macros
- need have two variants; the higher levels of macros may be the
- same whether strict or not.
-
- Normally, constant addresses which are the sum of a `symbol_ref'
- and an integer are stored inside a `const' RTX to mark them as
- constant. Therefore, there is no need to recognize such sums
- specifically as legitimate addresses. Normally you would simply
- recognize any `const' as legitimate.
-
- Usually `PRINT_OPERAND_ADDRESS' is not prepared to handle constant
- sums that are not marked with `const'. It assumes that a naked
- `plus' indicates indexing. If so, then you _must_ reject such
- naked constant sums as illegitimate addresses, so that none of
- them will be given to `PRINT_OPERAND_ADDRESS'.
-
- On some machines, whether a symbolic address is legitimate depends
- on the section that the address refers to. On these machines,
- define the macro `ENCODE_SECTION_INFO' to store the information
- into the `symbol_ref', and then check for it here. When you see a
- `const', you will have to look inside it to find the `symbol_ref'
- in order to determine the section. *Note Assembler Format::.
-
- The best way to modify the name string is by adding text to the
- beginning, with suitable punctuation to prevent any ambiguity.
- Allocate the new name in `saveable_obstack'. You will have to
- modify `ASM_OUTPUT_LABELREF' to remove and decode the added text
- and output the name accordingly, and define `STRIP_NAME_ENCODING'
- to access the original name string.
-
- You can check the information stored here into the `symbol_ref' in
- the definitions of the macros `GO_IF_LEGITIMATE_ADDRESS' and
- `PRINT_OPERAND_ADDRESS'.
-
-`REG_OK_FOR_BASE_P (X)'
- A C expression that is nonzero if X (assumed to be a `reg' RTX) is
- valid for use as a base register. For hard registers, it should
- always accept those which the hardware permits and reject the
- others. Whether the macro accepts or rejects pseudo registers
- must be controlled by `REG_OK_STRICT' as described above. This
- usually requires two variant definitions, of which `REG_OK_STRICT'
- controls the one actually used.
-
-`REG_MODE_OK_FOR_BASE_P (X, MODE)'
- A C expression that is just like `REG_OK_FOR_BASE_P', except that
- that expression may examine the mode of the memory reference in
- MODE. You should define this macro if the mode of the memory
- reference affects whether a register may be used as a base
- register. If you define this macro, the compiler will use it
- instead of `REG_OK_FOR_BASE_P'.
-
-`REG_OK_FOR_INDEX_P (X)'
- A C expression that is nonzero if X (assumed to be a `reg' RTX) is
- valid for use as an index register.
-
- The difference between an index register and a base register is
- that the index register may be scaled. If an address involves the
- sum of two registers, neither one of them scaled, then either one
- may be labeled the "base" and the other the "index"; but whichever
- labeling is used must fit the machine's constraints of which
- registers may serve in each capacity. The compiler will try both
- labelings, looking for one that is valid, and will reload one or
- both registers only if neither labeling works.
-
-`FIND_BASE_TERM (X)'
- A C expression to determine the base term of address X. This
- macro is used in only one place: `find_base_term' in alias.c.
-
- It is always safe for this macro to not be defined. It exists so
- that alias analysis can understand machine-dependent addresses.
-
- The typical use of this macro is to handle addresses containing a
- label_ref or symbol_ref within an UNSPEC.
-
-`LEGITIMIZE_ADDRESS (X, OLDX, MODE, WIN)'
- A C compound statement that attempts to replace X with a valid
- memory address for an operand of mode MODE. WIN will be a C
- statement label elsewhere in the code; the macro definition may use
-
- GO_IF_LEGITIMATE_ADDRESS (MODE, X, WIN);
-
- to avoid further processing if the address has become legitimate.
-
- X will always be the result of a call to `break_out_memory_refs',
- and OLDX will be the operand that was given to that function to
- produce X.
-
- The code generated by this macro should not alter the substructure
- of X. If it transforms X into a more legitimate form, it should
- assign X (which will always be a C variable) a new value.
-
- It is not necessary for this macro to come up with a legitimate
- address. The compiler has standard ways of doing so in all cases.
- In fact, it is safe for this macro to do nothing. But often a
- machine-dependent strategy can generate better code.
-
-`LEGITIMIZE_RELOAD_ADDRESS (X, MODE, OPNUM, TYPE, IND_LEVELS, WIN)'
- A C compound statement that attempts to replace X, which is an
- address that needs reloading, with a valid memory address for an
- operand of mode MODE. WIN will be a C statement label elsewhere
- in the code. It is not necessary to define this macro, but it
- might be useful for performance reasons.
-
- For example, on the i386, it is sometimes possible to use a single
- reload register instead of two by reloading a sum of two pseudo
- registers into a register. On the other hand, for number of RISC
- processors offsets are limited so that often an intermediate
- address needs to be generated in order to address a stack slot.
- By defining `LEGITIMIZE_RELOAD_ADDRESS' appropriately, the
- intermediate addresses generated for adjacent some stack slots can
- be made identical, and thus be shared.
-
- _Note_: This macro should be used with caution. It is necessary
- to know something of how reload works in order to effectively use
- this, and it is quite easy to produce macros that build in too
- much knowledge of reload internals.
-
- _Note_: This macro must be able to reload an address created by a
- previous invocation of this macro. If it fails to handle such
- addresses then the compiler may generate incorrect code or abort.
-
- The macro definition should use `push_reload' to indicate parts
- that need reloading; OPNUM, TYPE and IND_LEVELS are usually
- suitable to be passed unaltered to `push_reload'.
-
- The code generated by this macro must not alter the substructure of
- X. If it transforms X into a more legitimate form, it should
- assign X (which will always be a C variable) a new value. This
- also applies to parts that you change indirectly by calling
- `push_reload'.
-
- The macro definition may use `strict_memory_address_p' to test if
- the address has become legitimate.
-
- If you want to change only a part of X, one standard way of doing
- this is to use `copy_rtx'. Note, however, that is unshares only a
- single level of rtl. Thus, if the part to be changed is not at the
- top level, you'll need to replace first the top level. It is not
- necessary for this macro to come up with a legitimate address;
- but often a machine-dependent strategy can generate better code.
-
-`GO_IF_MODE_DEPENDENT_ADDRESS (ADDR, LABEL)'
- A C statement or compound statement with a conditional `goto
- LABEL;' executed if memory address X (an RTX) can have different
- meanings depending on the machine mode of the memory reference it
- is used for or if the address is valid for some modes but not
- others.
-
- Autoincrement and autodecrement addresses typically have
- mode-dependent effects because the amount of the increment or
- decrement is the size of the operand being addressed. Some
- machines have other mode-dependent addresses. Many RISC machines
- have no mode-dependent addresses.
-
- You may assume that ADDR is a valid address for the machine.
-
-`LEGITIMATE_CONSTANT_P (X)'
- A C expression that is nonzero if X is a legitimate constant for
- an immediate operand on the target machine. You can assume that X
- satisfies `CONSTANT_P', so you need not check this. In fact, `1'
- is a suitable definition for this macro on machines where anything
- `CONSTANT_P' is valid.
-
-\1f
-File: gccint.info, Node: Condition Code, Next: Costs, Prev: Addressing Modes, Up: Target Macros
-
-Condition Code Status
-=====================
-
- This describes the condition code status.
-
- The file `conditions.h' defines a variable `cc_status' to describe
-how the condition code was computed (in case the interpretation of the
-condition code depends on the instruction that it was set by). This
-variable contains the RTL expressions on which the condition code is
-currently based, and several standard flags.
-
- Sometimes additional machine-specific flags must be defined in the
-machine description header file. It can also add additional
-machine-specific information by defining `CC_STATUS_MDEP'.
-
-`CC_STATUS_MDEP'
- C code for a data type which is used for declaring the `mdep'
- component of `cc_status'. It defaults to `int'.
-
- This macro is not used on machines that do not use `cc0'.
-
-`CC_STATUS_MDEP_INIT'
- A C expression to initialize the `mdep' field to "empty". The
- default definition does nothing, since most machines don't use the
- field anyway. If you want to use the field, you should probably
- define this macro to initialize it.
-
- This macro is not used on machines that do not use `cc0'.
-
-`NOTICE_UPDATE_CC (EXP, INSN)'
- A C compound statement to set the components of `cc_status'
- appropriately for an insn INSN whose body is EXP. It is this
- macro's responsibility to recognize insns that set the condition
- code as a byproduct of other activity as well as those that
- explicitly set `(cc0)'.
-
- This macro is not used on machines that do not use `cc0'.
-
- If there are insns that do not set the condition code but do alter
- other machine registers, this macro must check to see whether they
- invalidate the expressions that the condition code is recorded as
- reflecting. For example, on the 68000, insns that store in address
- registers do not set the condition code, which means that usually
- `NOTICE_UPDATE_CC' can leave `cc_status' unaltered for such insns.
- But suppose that the previous insn set the condition code based
- on location `a4@(102)' and the current insn stores a new value in
- `a4'. Although the condition code is not changed by this, it will
- no longer be true that it reflects the contents of `a4@(102)'.
- Therefore, `NOTICE_UPDATE_CC' must alter `cc_status' in this case
- to say that nothing is known about the condition code value.
-
- The definition of `NOTICE_UPDATE_CC' must be prepared to deal with
- the results of peephole optimization: insns whose patterns are
- `parallel' RTXs containing various `reg', `mem' or constants which
- are just the operands. The RTL structure of these insns is not
- sufficient to indicate what the insns actually do. What
- `NOTICE_UPDATE_CC' should do when it sees one is just to run
- `CC_STATUS_INIT'.
-
- A possible definition of `NOTICE_UPDATE_CC' is to call a function
- that looks at an attribute (*note Insn Attributes::) named, for
- example, `cc'. This avoids having detailed information about
- patterns in two places, the `md' file and in `NOTICE_UPDATE_CC'.
-
-`EXTRA_CC_MODES'
- A list of additional modes for condition code values in registers
- (*note Jump Patterns::). This macro should expand to a sequence of
- calls of the macro `CC' separated by white space. `CC' takes two
- arguments. The first is the enumeration name of the mode, which
- should begin with `CC' and end with `mode'. The second is a C
- string giving the printable name of the mode; it should be the
- same as the first argument, but with the trailing `mode' removed.
-
- You should only define this macro if additional modes are required.
-
- A sample definition of `EXTRA_CC_MODES' is:
- #define EXTRA_CC_MODES \
- CC(CC_NOOVmode, "CC_NOOV") \
- CC(CCFPmode, "CCFP") \
- CC(CCFPEmode, "CCFPE")
-
-`SELECT_CC_MODE (OP, X, Y)'
- Returns a mode from class `MODE_CC' to be used when comparison
- operation code OP is applied to rtx X and Y. For example, on the
- Sparc, `SELECT_CC_MODE' is defined as (see *note Jump Patterns::
- for a description of the reason for this definition)
-
- #define SELECT_CC_MODE(OP,X,Y) \
- (GET_MODE_CLASS (GET_MODE (X)) == MODE_FLOAT \
- ? ((OP == EQ || OP == NE) ? CCFPmode : CCFPEmode) \
- : ((GET_CODE (X) == PLUS || GET_CODE (X) == MINUS \
- || GET_CODE (X) == NEG) \
- ? CC_NOOVmode : CCmode))
-
- You need not define this macro if `EXTRA_CC_MODES' is not defined.
-
-`CANONICALIZE_COMPARISON (CODE, OP0, OP1)'
- On some machines not all possible comparisons are defined, but you
- can convert an invalid comparison into a valid one. For example,
- the Alpha does not have a `GT' comparison, but you can use an `LT'
- comparison instead and swap the order of the operands.
-
- On such machines, define this macro to be a C statement to do any
- required conversions. CODE is the initial comparison code and OP0
- and OP1 are the left and right operands of the comparison,
- respectively. You should modify CODE, OP0, and OP1 as required.
-
- GCC will not assume that the comparison resulting from this macro
- is valid but will see if the resulting insn matches a pattern in
- the `md' file.
-
- You need not define this macro if it would never change the
- comparison code or operands.
-
-`REVERSIBLE_CC_MODE (MODE)'
- A C expression whose value is one if it is always safe to reverse a
- comparison whose mode is MODE. If `SELECT_CC_MODE' can ever
- return MODE for a floating-point inequality comparison, then
- `REVERSIBLE_CC_MODE (MODE)' must be zero.
-
- You need not define this macro if it would always returns zero or
- if the floating-point format is anything other than
- `IEEE_FLOAT_FORMAT'. For example, here is the definition used on
- the Sparc, where floating-point inequality comparisons are always
- given `CCFPEmode':
-
- #define REVERSIBLE_CC_MODE(MODE) ((MODE) != CCFPEmode)
-
- A C expression whose value is reversed condition code of the CODE
- for comparison done in CC_MODE MODE. The macro is used only in
- case `REVERSIBLE_CC_MODE (MODE)' is nonzero. Define this macro in
- case machine has some non-standard way how to reverse certain
- conditionals. For instance in case all floating point conditions
- are non-trapping, compiler may freely convert unordered compares
- to ordered one. Then definition may look like:
-
- #define REVERSE_CONDITION(CODE, MODE) \
- ((MODE) != CCFPmode ? reverse_condition (CODE) \
- : reverse_condition_maybe_unordered (CODE))
-
-`REVERSE_CONDEXEC_PREDICATES_P (CODE1, CODE2)'
- A C expression that returns true if the conditional execution
- predicate CODE1 is the inverse of CODE2 and vice versa. Define
- this to return 0 if the target has conditional execution
- predicates that cannot be reversed safely. If no expansion is
- specified, this macro is defined as follows:
-
- #define REVERSE_CONDEXEC_PREDICATES_P (x, y) \
- ((x) == reverse_condition (y))
-
-
-\1f
-File: gccint.info, Node: Costs, Next: Scheduling, Prev: Condition Code, Up: Target Macros
-
-Describing Relative Costs of Operations
-=======================================
-
- These macros let you describe the relative speed of various
-operations on the target machine.
-
-`CONST_COSTS (X, CODE, OUTER_CODE)'
- A part of a C `switch' statement that describes the relative costs
- of constant RTL expressions. It must contain `case' labels for
- expression codes `const_int', `const', `symbol_ref', `label_ref'
- and `const_double'. Each case must ultimately reach a `return'
- statement to return the relative cost of the use of that kind of
- constant value in an expression. The cost may depend on the
- precise value of the constant, which is available for examination
- in X, and the rtx code of the expression in which it is contained,
- found in OUTER_CODE.
-
- CODE is the expression code--redundant, since it can be obtained
- with `GET_CODE (X)'.
-
-`RTX_COSTS (X, CODE, OUTER_CODE)'
- Like `CONST_COSTS' but applies to nonconstant RTL expressions.
- This can be used, for example, to indicate how costly a multiply
- instruction is. In writing this macro, you can use the construct
- `COSTS_N_INSNS (N)' to specify a cost equal to N fast
- instructions. OUTER_CODE is the code of the expression in which X
- is contained.
-
- This macro is optional; do not define it if the default cost
- assumptions are adequate for the target machine.
-
-`DEFAULT_RTX_COSTS (X, CODE, OUTER_CODE)'
- This macro, if defined, is called for any case not handled by the
- `RTX_COSTS' or `CONST_COSTS' macros. This eliminates the need to
- put case labels into the macro, but the code, or any functions it
- calls, must assume that the RTL in X could be of any type that has
- not already been handled. The arguments are the same as for
- `RTX_COSTS', and the macro should execute a return statement giving
- the cost of any RTL expressions that it can handle. The default
- cost calculation is used for any RTL for which this macro does not
- return a value.
-
- This macro is optional; do not define it if the default cost
- assumptions are adequate for the target machine.
-
-`ADDRESS_COST (ADDRESS)'
- An expression giving the cost of an addressing mode that contains
- ADDRESS. If not defined, the cost is computed from the ADDRESS
- expression and the `CONST_COSTS' values.
-
- For most CISC machines, the default cost is a good approximation
- of the true cost of the addressing mode. However, on RISC
- machines, all instructions normally have the same length and
- execution time. Hence all addresses will have equal costs.
-
- In cases where more than one form of an address is known, the form
- with the lowest cost will be used. If multiple forms have the
- same, lowest, cost, the one that is the most complex will be used.
-
- For example, suppose an address that is equal to the sum of a
- register and a constant is used twice in the same basic block.
- When this macro is not defined, the address will be computed in a
- register and memory references will be indirect through that
- register. On machines where the cost of the addressing mode
- containing the sum is no higher than that of a simple indirect
- reference, this will produce an additional instruction and
- possibly require an additional register. Proper specification of
- this macro eliminates this overhead for such machines.
-
- Similar use of this macro is made in strength reduction of loops.
-
- ADDRESS need not be valid as an address. In such a case, the cost
- is not relevant and can be any value; invalid addresses need not be
- assigned a different cost.
-
- On machines where an address involving more than one register is as
- cheap as an address computation involving only one register,
- defining `ADDRESS_COST' to reflect this can cause two registers to
- be live over a region of code where only one would have been if
- `ADDRESS_COST' were not defined in that manner. This effect should
- be considered in the definition of this macro. Equivalent costs
- should probably only be given to addresses with different numbers
- of registers on machines with lots of registers.
-
- This macro will normally either not be defined or be defined as a
- constant.
-
-`REGISTER_MOVE_COST (MODE, FROM, TO)'
- A C expression for the cost of moving data of mode MODE from a
- register in class FROM to one in class TO. The classes are
- expressed using the enumeration values such as `GENERAL_REGS'. A
- value of 2 is the default; other values are interpreted relative to
- that.
-
- It is not required that the cost always equal 2 when FROM is the
- same as TO; on some machines it is expensive to move between
- registers if they are not general registers.
-
- If reload sees an insn consisting of a single `set' between two
- hard registers, and if `REGISTER_MOVE_COST' applied to their
- classes returns a value of 2, reload does not check to ensure that
- the constraints of the insn are met. Setting a cost of other than
- 2 will allow reload to verify that the constraints are met. You
- should do this if the `movM' pattern's constraints do not allow
- such copying.
-
-`MEMORY_MOVE_COST (MODE, CLASS, IN)'
- A C expression for the cost of moving data of mode MODE between a
- register of class CLASS and memory; IN is zero if the value is to
- be written to memory, nonzero if it is to be read in. This cost
- is relative to those in `REGISTER_MOVE_COST'. If moving between
- registers and memory is more expensive than between two registers,
- you should define this macro to express the relative cost.
-
- If you do not define this macro, GCC uses a default cost of 4 plus
- the cost of copying via a secondary reload register, if one is
- needed. If your machine requires a secondary reload register to
- copy between memory and a register of CLASS but the reload
- mechanism is more complex than copying via an intermediate, define
- this macro to reflect the actual cost of the move.
-
- GCC defines the function `memory_move_secondary_cost' if secondary
- reloads are needed. It computes the costs due to copying via a
- secondary register. If your machine copies from memory using a
- secondary register in the conventional way but the default base
- value of 4 is not correct for your machine, define this macro to
- add some other value to the result of that function. The
- arguments to that function are the same as to this macro.
-
-`BRANCH_COST'
- A C expression for the cost of a branch instruction. A value of 1
- is the default; other values are interpreted relative to that.
-
- Here are additional macros which do not specify precise relative
-costs, but only that certain actions are more expensive than GCC would
-ordinarily expect.
-
-`SLOW_BYTE_ACCESS'
- Define this macro as a C expression which is nonzero if accessing
- less than a word of memory (i.e. a `char' or a `short') is no
- faster than accessing a word of memory, i.e., if such access
- require more than one instruction or if there is no difference in
- cost between byte and (aligned) word loads.
-
- When this macro is not defined, the compiler will access a field by
- finding the smallest containing object; when it is defined, a
- fullword load will be used if alignment permits. Unless bytes
- accesses are faster than word accesses, using word accesses is
- preferable since it may eliminate subsequent memory access if
- subsequent accesses occur to other fields in the same word of the
- structure, but to different bytes.
-
-`SLOW_UNALIGNED_ACCESS (MODE, ALIGNMENT)'
- Define this macro to be the value 1 if memory accesses described
- by the MODE and ALIGNMENT parameters have a cost many times greater
- than aligned accesses, for example if they are emulated in a trap
- handler.
-
- When this macro is nonzero, the compiler will act as if
- `STRICT_ALIGNMENT' were nonzero when generating code for block
- moves. This can cause significantly more instructions to be
- produced. Therefore, do not set this macro nonzero if unaligned
- accesses only add a cycle or two to the time for a memory access.
-
- If the value of this macro is always zero, it need not be defined.
- If this macro is defined, it should produce a nonzero value when
- `STRICT_ALIGNMENT' is nonzero.
-
-`DONT_REDUCE_ADDR'
- Define this macro to inhibit strength reduction of memory
- addresses. (On some machines, such strength reduction seems to do
- harm rather than good.)
-
-`MOVE_RATIO'
- The threshold of number of scalar memory-to-memory move insns,
- _below_ which a sequence of insns should be generated instead of a
- string move insn or a library call. Increasing the value will
- always make code faster, but eventually incurs high cost in
- increased code size.
-
- Note that on machines where the corresponding move insn is a
- `define_expand' that emits a sequence of insns, this macro counts
- the number of such sequences.
-
- If you don't define this, a reasonable default is used.
-
-`MOVE_BY_PIECES_P (SIZE, ALIGNMENT)'
- A C expression used to determine whether `move_by_pieces' will be
- used to copy a chunk of memory, or whether some other block move
- mechanism will be used. Defaults to 1 if `move_by_pieces_ninsns'
- returns less than `MOVE_RATIO'.
-
-`MOVE_MAX_PIECES'
- A C expression used by `move_by_pieces' to determine the largest
- unit a load or store used to copy memory is. Defaults to
- `MOVE_MAX'.
-
-`USE_LOAD_POST_INCREMENT (MODE)'
- A C expression used to determine whether a load postincrement is a
- good thing to use for a given mode. Defaults to the value of
- `HAVE_POST_INCREMENT'.
-
-`USE_LOAD_POST_DECREMENT (MODE)'
- A C expression used to determine whether a load postdecrement is a
- good thing to use for a given mode. Defaults to the value of
- `HAVE_POST_DECREMENT'.
-
-`USE_LOAD_PRE_INCREMENT (MODE)'
- A C expression used to determine whether a load preincrement is a
- good thing to use for a given mode. Defaults to the value of
- `HAVE_PRE_INCREMENT'.
-
-`USE_LOAD_PRE_DECREMENT (MODE)'
- A C expression used to determine whether a load predecrement is a
- good thing to use for a given mode. Defaults to the value of
- `HAVE_PRE_DECREMENT'.
-
-`USE_STORE_POST_INCREMENT (MODE)'
- A C expression used to determine whether a store postincrement is
- a good thing to use for a given mode. Defaults to the value of
- `HAVE_POST_INCREMENT'.
-
-`USE_STORE_POST_DECREMENT (MODE)'
- A C expression used to determine whether a store postdecrement is
- a good thing to use for a given mode. Defaults to the value of
- `HAVE_POST_DECREMENT'.
-
-`USE_STORE_PRE_INCREMENT (MODE)'
- This macro is used to determine whether a store preincrement is a
- good thing to use for a given mode. Defaults to the value of
- `HAVE_PRE_INCREMENT'.
-
-`USE_STORE_PRE_DECREMENT (MODE)'
- This macro is used to determine whether a store predecrement is a
- good thing to use for a given mode. Defaults to the value of
- `HAVE_PRE_DECREMENT'.
-
-`NO_FUNCTION_CSE'
- Define this macro if it is as good or better to call a constant
- function address than to call an address kept in a register.
-
-`NO_RECURSIVE_FUNCTION_CSE'
- Define this macro if it is as good or better for a function to call
- itself with an explicit address than to call an address kept in a
- register.
-
-\1f
-File: gccint.info, Node: Scheduling, Next: Sections, Prev: Costs, Up: Target Macros
-
-Adjusting the Instruction Scheduler
-===================================
-
- The instruction scheduler may need a fair amount of machine-specific
-adjustment in order to produce good code. GCC provides several target
-hooks for this purpose. It is usually enough to define just a few of
-them: try the first ones in this list first.
-
- - Target Hook: int TARGET_SCHED_ISSUE_RATE (void)
- This hook returns the maximum number of instructions that can ever
- issue at the same time on the target machine. The default is one.
- This value must be constant over the entire compilation. If you
- need it to vary depending on what the instructions are, you must
- use `TARGET_SCHED_VARIABLE_ISSUE'.
-
- - Target Hook: int TARGET_SCHED_VARIABLE_ISSUE (FILE *FILE, int
- VERBOSE, rtx INSN, int MORE)
- This hook is executed by the scheduler after it has scheduled an
- insn from the ready list. It should return the number of insns
- which can still be issued in the current cycle. Normally this is
- `MORE - 1'. You should define this hook if some insns take more
- machine resources than others, so that fewer insns can follow them
- in the same cycle. FILE is either a null pointer, or a stdio
- stream to write any debug output to. VERBOSE is the verbose level
- provided by `-fsched-verbose-N'. INSN is the instruction that was
- scheduled.
-
- - Target Hook: int TARGET_SCHED_ADJUST_COST (rtx INSN, rtx LINK, rtx
- DEP_INSN, int COST)
- This function corrects the value of COST based on the relationship
- between INSN and DEP_INSN through the dependence LINK. It should
- return the new value. The default is to make no adjustment to
- COST. This can be used for example to specify to the scheduler
- that an output- or anti-dependence does not incur the same cost as
- a data-dependence.
-
- - Target Hook: int TARGET_SCHED_ADJUST_PRIORITY (rtx INSN, int
- PRIORITY)
- This hook adjusts the integer scheduling priority PRIORITY of
- INSN. It should return the new priority. Reduce the priority to
- execute INSN earlier, increase the priority to execute INSN later.
- Do not define this hook if you do not need to adjust the
- scheduling priorities of insns.
-
- - Target Hook: int TARGET_SCHED_REORDER (FILE *FILE, int VERBOSE, rtx
- *READY, int *N_READYP, int CLOCK)
- This hook is executed by the scheduler after it has scheduled the
- ready list, to allow the machine description to reorder it (for
- example to combine two small instructions together on `VLIW'
- machines). FILE is either a null pointer, or a stdio stream to
- write any debug output to. VERBOSE is the verbose level provided
- by `-fsched-verbose-N'. READY is a pointer to the ready list of
- instructions that are ready to be scheduled. N_READYP is a
- pointer to the number of elements in the ready list. The scheduler
- reads the ready list in reverse order, starting with
- READY[*N_READYP-1] and going to READY[0]. CLOCK is the timer tick
- of the scheduler. You may modify the ready list and the number of
- ready insns. The return value is the number of insns that can
- issue this cycle; normally this is just `issue_rate'. See also
- `TARGET_SCHED_REORDER2'.
-
- - Target Hook: int TARGET_SCHED_REORDER2 (FILE *FILE, int VERBOSE, rtx
- *READY, int *N_READY, CLOCK)
- Like `TARGET_SCHED_REORDER', but called at a different time. That
- function is called whenever the scheduler starts a new cycle.
- This one is called once per iteration over a cycle, immediately
- after `TARGET_SCHED_VARIABLE_ISSUE'; it can reorder the ready list
- and return the number of insns to be scheduled in the same cycle.
- Defining this hook can be useful if there are frequent situations
- where scheduling one insn causes other insns to become ready in
- the same cycle. These other insns can then be taken into account
- properly.
-
- - Target Hook: void TARGET_SCHED_INIT (FILE *FILE, int VERBOSE, int
- MAX_READY)
- This hook is executed by the scheduler at the beginning of each
- block of instructions that are to be scheduled. FILE is either a
- null pointer, or a stdio stream to write any debug output to.
- VERBOSE is the verbose level provided by `-fsched-verbose-N'.
- MAX_READY is the maximum number of insns in the current scheduling
- region that can be live at the same time. This can be used to
- allocate scratch space if it is needed, e.g. by
- `TARGET_SCHED_REORDER'.
-
- - Target Hook: void TARGET_SCHED_FINISH (FILE *FILE, int VERBOSE)
- This hook is executed by the scheduler at the end of each block of
- instructions that are to be scheduled. It can be used to perform
- cleanup of any actions done by the other scheduling hooks. FILE
- is either a null pointer, or a stdio stream to write any debug
- output to. VERBOSE is the verbose level provided by
- `-fsched-verbose-N'.
-
- - Target Hook: rtx TARGET_SCHED_CYCLE_DISPLAY (int CLOCK, rtx LAST)
- This hook is called in verbose mode only, at the beginning of each
- pass over a basic block. It should insert an insn into the chain
- after LAST, which has no effect, but records the value CLOCK in
- RTL dumps and assembly output. Define this hook only if you need
- this level of detail about what the scheduler is doing.
-
-\1f
-File: gccint.info, Node: Sections, Next: PIC, Prev: Scheduling, Up: Target Macros
-
-Dividing the Output into Sections (Texts, Data, ...)
-====================================================
-
- An object file is divided into sections containing different types of
-data. In the most common case, there are three sections: the "text
-section", which holds instructions and read-only data; the "data
-section", which holds initialized writable data; and the "bss section",
-which holds uninitialized data. Some systems have other kinds of
-sections.
-
- The compiler must tell the assembler when to switch sections. These
-macros control what commands to output to tell the assembler this. You
-can also define additional sections.
-
-`TEXT_SECTION_ASM_OP'
- A C expression whose value is a string, including spacing,
- containing the assembler operation that should precede
- instructions and read-only data. Normally `"\t.text"' is right.
-
-`TEXT_SECTION'
- A C statement that switches to the default section containing
- instructions. Normally this is not needed, as simply defining
- `TEXT_SECTION_ASM_OP' is enough. The MIPS port uses this to sort
- all functions after all data declarations.
-
-`DATA_SECTION_ASM_OP'
- A C expression whose value is a string, including spacing,
- containing the assembler operation to identify the following data
- as writable initialized data. Normally `"\t.data"' is right.
-
-`SHARED_SECTION_ASM_OP'
- If defined, a C expression whose value is a string, including
- spacing, containing the assembler operation to identify the
- following data as shared data. If not defined,
- `DATA_SECTION_ASM_OP' will be used.
-
-`BSS_SECTION_ASM_OP'
- If defined, a C expression whose value is a string, including
- spacing, containing the assembler operation to identify the
- following data as uninitialized global data. If not defined, and
- neither `ASM_OUTPUT_BSS' nor `ASM_OUTPUT_ALIGNED_BSS' are defined,
- uninitialized global data will be output in the data section if
- `-fno-common' is passed, otherwise `ASM_OUTPUT_COMMON' will be
- used.
-
-`SHARED_BSS_SECTION_ASM_OP'
- If defined, a C expression whose value is a string, including
- spacing, containing the assembler operation to identify the
- following data as uninitialized global shared data. If not
- defined, and `BSS_SECTION_ASM_OP' is, the latter will be used.
-
-`INIT_SECTION_ASM_OP'
- If defined, a C expression whose value is a string, including
- spacing, containing the assembler operation to identify the
- following data as initialization code. If not defined, GCC will
- assume such a section does not exist.
-
-`FINI_SECTION_ASM_OP'
- If defined, a C expression whose value is a string, including
- spacing, containing the assembler operation to identify the
- following data as finalization code. If not defined, GCC will
- assume such a section does not exist.
-
-`CRT_CALL_STATIC_FUNCTION (SECTION_OP, FUNCTION)'
- If defined, an ASM statement that switches to a different section
- via SECTION_OP, calls FUNCTION, and switches back to the text
- section. This is used in `crtstuff.c' if `INIT_SECTION_ASM_OP' or
- `FINI_SECTION_ASM_OP' to calls to initialization and finalization
- functions from the init and fini sections. By default, this macro
- uses a simple function call. Some ports need hand-crafted
- assembly code to avoid dependencies on registers initialized in
- the function prologue or to ensure that constant pools don't end
- up too far way in the text section.
-
-`FORCE_CODE_SECTION_ALIGN'
- If defined, an ASM statement that aligns a code section to some
- arbitrary boundary. This is used to force all fragments of the
- `.init' and `.fini' sections to have to same alignment and thus
- prevent the linker from having to add any padding.
-
-`EXTRA_SECTIONS'
- A list of names for sections other than the standard two, which are
- `in_text' and `in_data'. You need not define this macro on a
- system with no other sections (that GCC needs to use).
-
-`EXTRA_SECTION_FUNCTIONS'
- One or more functions to be defined in `varasm.c'. These
- functions should do jobs analogous to those of `text_section' and
- `data_section', for your additional sections. Do not define this
- macro if you do not define `EXTRA_SECTIONS'.
-
-`READONLY_DATA_SECTION'
- On most machines, read-only variables, constants, and jump tables
- are placed in the text section. If this is not the case on your
- machine, this macro should be defined to be the name of a function
- (either `data_section' or a function defined in `EXTRA_SECTIONS')
- that switches to the section to be used for read-only items.
-
- If these items should be placed in the text section, this macro
- should not be defined.
-
-`SELECT_SECTION (EXP, RELOC, ALIGN)'
- A C statement or statements to switch to the appropriate section
- for output of EXP. You can assume that EXP is either a `VAR_DECL'
- node or a constant of some sort. RELOC indicates whether the
- initial value of EXP requires link-time relocations. Bit 1 is set
- when variable contains local relocations only, while bit 2 is set
- for global relocations. Select the section by calling
- `text_section' or one of the alternatives for other sections.
- ALIGN is the constant alignment in bits.
-
- Do not define this macro if you put all read-only variables and
- constants in the read-only data section (usually the text section).
-
-`SELECT_RTX_SECTION (MODE, RTX, ALIGN)'
- A C statement or statements to switch to the appropriate section
- for output of RTX in mode MODE. You can assume that RTX is some
- kind of constant in RTL. The argument MODE is redundant except in
- the case of a `const_int' rtx. Select the section by calling
- `text_section' or one of the alternatives for other sections.
- ALIGN is the constant alignment in bits.
-
- Do not define this macro if you put all constants in the read-only
- data section.
-
-`JUMP_TABLES_IN_TEXT_SECTION'
- Define this macro to be an expression with a nonzero value if jump
- tables (for `tablejump' insns) should be output in the text
- section, along with the assembler instructions. Otherwise, the
- readonly data section is used.
-
- This macro is irrelevant if there is no separate readonly data
- section.
-
-`ENCODE_SECTION_INFO (DECL)'
- Define this macro if references to a symbol or a constant must be
- treated differently depending on something about the variable or
- function named by the symbol (such as what section it is in).
-
- The macro definition, if any, is executed under two circumstances.
- One is immediately after the rtl for DECL that represents a
- variable or a function has been created and stored in `DECL_RTL
- (DECL)'. The value of the rtl will be a `mem' whose address is a
- `symbol_ref'. The other is immediately after the rtl for DECL
- that represents a constant has been created and stored in
- `TREE_CST_RTL (DECL)'. The macro is called once for each distinct
- constant in a source file.
-
- The usual thing for this macro to do is to record a flag in the
- `symbol_ref' (such as `SYMBOL_REF_FLAG') or to store a modified
- name string in the `symbol_ref' (if one bit is not enough
- information).
-
-`STRIP_NAME_ENCODING (VAR, SYM_NAME)'
- Decode SYM_NAME and store the real name part in VAR, sans the
- characters that encode section info. Define this macro if
- `ENCODE_SECTION_INFO' alters the symbol's name string.
-
-`UNIQUE_SECTION (DECL, RELOC)'
- A C statement to build up a unique section name, expressed as a
- `STRING_CST' node, and assign it to `DECL_SECTION_NAME (DECL)'.
- RELOC indicates whether the initial value of EXP requires
- link-time relocations. If you do not define this macro, GCC will
- use the symbol name prefixed by `.' as the section name. Note -
- this macro can now be called for uninitialized data items as well
- as initialized data and functions.
-
-\1f
-File: gccint.info, Node: PIC, Next: Assembler Format, Prev: Sections, Up: Target Macros
-
-Position Independent Code
-=========================
-
- This section describes macros that help implement generation of
-position independent code. Simply defining these macros is not enough
-to generate valid PIC; you must also add support to the macros
-`GO_IF_LEGITIMATE_ADDRESS' and `PRINT_OPERAND_ADDRESS', as well as
-`LEGITIMIZE_ADDRESS'. You must modify the definition of `movsi' to do
-something appropriate when the source operand contains a symbolic
-address. You may also need to alter the handling of switch statements
-so that they use relative addresses.
-
-`PIC_OFFSET_TABLE_REGNUM'
- The register number of the register used to address a table of
- static data addresses in memory. In some cases this register is
- defined by a processor's "application binary interface" (ABI).
- When this macro is defined, RTL is generated for this register
- once, as with the stack pointer and frame pointer registers. If
- this macro is not defined, it is up to the machine-dependent files
- to allocate such a register (if necessary). Note that this
- register must be fixed when in use (e.g. when `flag_pic' is true).
-
-`PIC_OFFSET_TABLE_REG_CALL_CLOBBERED'
- Define this macro if the register defined by
- `PIC_OFFSET_TABLE_REGNUM' is clobbered by calls. Do not define
- this macro if `PIC_OFFSET_TABLE_REGNUM' is not defined.
-
-`FINALIZE_PIC'
- By generating position-independent code, when two different
- programs (A and B) share a common library (libC.a), the text of
- the library can be shared whether or not the library is linked at
- the same address for both programs. In some of these
- environments, position-independent code requires not only the use
- of different addressing modes, but also special code to enable the
- use of these addressing modes.
-
- The `FINALIZE_PIC' macro serves as a hook to emit these special
- codes once the function is being compiled into assembly code, but
- not before. (It is not done before, because in the case of
- compiling an inline function, it would lead to multiple PIC
- prologues being included in functions which used inline functions
- and were compiled to assembly language.)
-
-`LEGITIMATE_PIC_OPERAND_P (X)'
- A C expression that is nonzero if X is a legitimate immediate
- operand on the target machine when generating position independent
- code. You can assume that X satisfies `CONSTANT_P', so you need
- not check this. You can also assume FLAG_PIC is true, so you need
- not check it either. You need not define this macro if all
- constants (including `SYMBOL_REF') can be immediate operands when
- generating position independent code.
-
-\1f
-File: gccint.info, Node: Assembler Format, Next: Debugging Info, Prev: PIC, Up: Target Macros
-
-Defining the Output Assembler Language
-======================================
-
- This section describes macros whose principal purpose is to describe
-how to write instructions in assembler language--rather than what the
-instructions do.
-
-* Menu:
-
-* File Framework:: Structural information for the assembler file.
-* Data Output:: Output of constants (numbers, strings, addresses).
-* Uninitialized Data:: Output of uninitialized variables.
-* Label Output:: Output and generation of labels.
-* Initialization:: General principles of initialization
- and termination routines.
-* Macros for Initialization::
- Specific macros that control the handling of
- initialization and termination routines.
-* Instruction Output:: Output of actual instructions.
-* Dispatch Tables:: Output of jump tables.
-* Exception Region Output:: Output of exception region code.
-* Alignment Output:: Pseudo ops for alignment and skipping data.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: File Framework, Next: Data Output, Up: Assembler Format
-
-The Overall Framework of an Assembler File
-------------------------------------------
-
- This describes the overall framework of an assembler file.
-
-`ASM_FILE_START (STREAM)'
- A C expression which outputs to the stdio stream STREAM some
- appropriate text to go at the start of an assembler file.
-
- Normally this macro is defined to output a line containing
- `#NO_APP', which is a comment that has no effect on most
- assemblers but tells the GNU assembler that it can save time by not
- checking for certain assembler constructs.
-
- On systems that use SDB, it is necessary to output certain
- commands; see `attasm.h'.
-
-`ASM_FILE_END (STREAM)'
- A C expression which outputs to the stdio stream STREAM some
- appropriate text to go at the end of an assembler file.
-
- If this macro is not defined, the default is to output nothing
- special at the end of the file. Most systems don't require any
- definition.
-
- On systems that use SDB, it is necessary to output certain
- commands; see `attasm.h'.
-
-`ASM_COMMENT_START'
- A C string constant describing how to begin a comment in the target
- assembler language. The compiler assumes that the comment will
- end at the end of the line.
-
-`ASM_APP_ON'
- A C string constant for text to be output before each `asm'
- statement or group of consecutive ones. Normally this is
- `"#APP"', which is a comment that has no effect on most assemblers
- but tells the GNU assembler that it must check the lines that
- follow for all valid assembler constructs.
-
-`ASM_APP_OFF'
- A C string constant for text to be output after each `asm'
- statement or group of consecutive ones. Normally this is
- `"#NO_APP"', which tells the GNU assembler to resume making the
- time-saving assumptions that are valid for ordinary compiler
- output.
-
-`ASM_OUTPUT_SOURCE_FILENAME (STREAM, NAME)'
- A C statement to output COFF information or DWARF debugging
- information which indicates that filename NAME is the current
- source file to the stdio stream STREAM.
-
- This macro need not be defined if the standard form of output for
- the file format in use is appropriate.
-
-`OUTPUT_QUOTED_STRING (STREAM, STRING)'
- A C statement to output the string STRING to the stdio stream
- STREAM. If you do not call the function `output_quoted_string' in
- your config files, GCC will only call it to output filenames to
- the assembler source. So you can use it to canonicalize the format
- of the filename using this macro.
-
-`ASM_OUTPUT_SOURCE_LINE (STREAM, LINE)'
- A C statement to output DBX or SDB debugging information before
- code for line number LINE of the current source file to the stdio
- stream STREAM.
-
- This macro need not be defined if the standard form of debugging
- information for the debugger in use is appropriate.
-
-`ASM_OUTPUT_IDENT (STREAM, STRING)'
- A C statement to output something to the assembler file to handle a
- `#ident' directive containing the text STRING. If this macro is
- not defined, nothing is output for a `#ident' directive.
-
-`OBJC_PROLOGUE'
- A C statement to output any assembler statements which are
- required to precede any Objective-C object definitions or message
- sending. The statement is executed only when compiling an
- Objective-C program.
-
- - Target Hook: void TARGET_ASM_NAMED_SECTION (const char *NAME,
- unsigned int FLAGS, unsigned int ALIGN)
- Output assembly directives to switch to section NAME. The section
- should have attributes as specified by FLAGS, which is a bit mask
- of the `SECTION_*' flags defined in `output.h'. If ALIGN is
- nonzero, it contains an alignment in bytes to be used for the
- section, otherwise some target default should be used. Only
- targets that must specify an alignment within the section
- directive need pay attention to ALIGN - we will still use
- `ASM_OUTPUT_ALIGN'.
-
- - Target Hook: bool TARGET_HAVE_NAMED_SECTIONS
- This flag is true if the target supports
- `TARGET_ASM_NAMED_SECTION'.
-
- - Target Hook: unsigned int TARGET_SECTION_TYPE_FLAGS (tree DECL,
- const char *NAME, int RELOC)
- Choose a set of section attributes for use by
- `TARGET_ASM_NAMED_SECTION' based on a variable or function decl, a
- section name, and whether or not the declaration's initializer may
- contain runtime relocations. DECL may be null, in which case
- read-write data should be assumed.
-
- The default version if this function handles choosing code vs data,
- read-only vs read-write data, and `flag_pic'. You should only
- need to override this if your target has special flags that might
- be set via `__attribute__'.
-
-\1f
-File: gccint.info, Node: Data Output, Next: Uninitialized Data, Prev: File Framework, Up: Assembler Format
-
-Output of Data
---------------
-
- - Target Hook: const char * TARGET_ASM_BYTE_OP
- - Target Hook: const char * TARGET_ASM_ALIGNED_HI_OP
- - Target Hook: const char * TARGET_ASM_ALIGNED_SI_OP
- - Target Hook: const char * TARGET_ASM_ALIGNED_DI_OP
- - Target Hook: const char * TARGET_ASM_ALIGNED_TI_OP
- - Target Hook: const char * TARGET_ASM_UNALIGNED_HI_OP
- - Target Hook: const char * TARGET_ASM_UNALIGNED_SI_OP
- - Target Hook: const char * TARGET_ASM_UNALIGNED_DI_OP
- - Target Hook: const char * TARGET_ASM_UNALIGNED_TI_OP
- These hooks specify assembly directives for creating certain kinds
- of integer object. The `TARGET_ASM_BYTE_OP' directive creates a
- byte-sized object, the `TARGET_ASM_ALIGNED_HI_OP' one creates an
- aligned two-byte object, and so on. Any of the hooks may be
- `NULL', indicating that no suitable directive is available.
-
- The compiler will print these strings at the start of a new line,
- followed immediately by the object's initial value. In most cases,
- the string should contain a tab, a pseudo-op, and then another tab.
-
- - Target Hook: bool TARGET_ASM_INTEGER (rtx X, unsigned int SIZE, int
- ALIGNED_P)
- The `assemble_integer' function uses this hook to output an
- integer object. X is the object's value, SIZE is its size in
- bytes and ALIGNED_P indicates whether it is aligned. The function
- should return `true' if it was able to output the object. If it
- returns false, `assemble_integer' will try to split the object
- into smaller parts.
-
- The default implementation of this hook will use the
- `TARGET_ASM_BYTE_OP' family of strings, returning `false' when the
- relevant string is `NULL'.
-
-`OUTPUT_ADDR_CONST_EXTRA (STREAM, X, FAIL)'
- A C statement to recognize RTX patterns that `output_addr_const'
- can't deal with, and output assembly code to STREAM corresponding
- to the pattern X. This may be used to allow machine-dependent
- `UNSPEC's to appear within constants.
-
- If `OUTPUT_ADDR_CONST_EXTRA' fails to recognize a pattern, it must
- `goto fail', so that a standard error message is printed. If it
- prints an error message itself, by calling, for example,
- `output_operand_lossage', it may just complete normally.
-
-`ASM_OUTPUT_ASCII (STREAM, PTR, LEN)'
- A C statement to output to the stdio stream STREAM an assembler
- instruction to assemble a string constant containing the LEN bytes
- at PTR. PTR will be a C expression of type `char *' and LEN a C
- expression of type `int'.
-
- If the assembler has a `.ascii' pseudo-op as found in the Berkeley
- Unix assembler, do not define the macro `ASM_OUTPUT_ASCII'.
-
-`ASM_OUTPUT_FDESC (STREAM, DECL, N)'
- A C statement to output word N of a function descriptor for DECL.
- This must be defined if `TARGET_VTABLE_USES_DESCRIPTORS' is
- defined, and is otherwise unused.
-
-`CONSTANT_POOL_BEFORE_FUNCTION'
- You may define this macro as a C expression. You should define the
- expression to have a nonzero value if GCC should output the
- constant pool for a function before the code for the function, or
- a zero value if GCC should output the constant pool after the
- function. If you do not define this macro, the usual case, GCC
- will output the constant pool before the function.
-
-`ASM_OUTPUT_POOL_PROLOGUE (FILE, FUNNAME, FUNDECL, SIZE)'
- A C statement to output assembler commands to define the start of
- the constant pool for a function. FUNNAME is a string giving the
- name of the function. Should the return type of the function be
- required, it can be obtained via FUNDECL. SIZE is the size, in
- bytes, of the constant pool that will be written immediately after
- this call.
-
- If no constant-pool prefix is required, the usual case, this macro
- need not be defined.
-
-`ASM_OUTPUT_SPECIAL_POOL_ENTRY (FILE, X, MODE, ALIGN, LABELNO, JUMPTO)'
- A C statement (with or without semicolon) to output a constant in
- the constant pool, if it needs special treatment. (This macro
- need not do anything for RTL expressions that can be output
- normally.)
-
- The argument FILE is the standard I/O stream to output the
- assembler code on. X is the RTL expression for the constant to
- output, and MODE is the machine mode (in case X is a `const_int').
- ALIGN is the required alignment for the value X; you should
- output an assembler directive to force this much alignment.
-
- The argument LABELNO is a number to use in an internal label for
- the address of this pool entry. The definition of this macro is
- responsible for outputting the label definition at the proper
- place. Here is how to do this:
-
- ASM_OUTPUT_INTERNAL_LABEL (FILE, "LC", LABELNO);
-
- When you output a pool entry specially, you should end with a
- `goto' to the label JUMPTO. This will prevent the same pool entry
- from being output a second time in the usual manner.
-
- You need not define this macro if it would do nothing.
-
-`CONSTANT_AFTER_FUNCTION_P (EXP)'
- Define this macro as a C expression which is nonzero if the
- constant EXP, of type `tree', should be output after the code for a
- function. The compiler will normally output all constants before
- the function; you need not define this macro if this is OK.
-
-`ASM_OUTPUT_POOL_EPILOGUE (FILE FUNNAME FUNDECL SIZE)'
- A C statement to output assembler commands to at the end of the
- constant pool for a function. FUNNAME is a string giving the name
- of the function. Should the return type of the function be
- required, you can obtain it via FUNDECL. SIZE is the size, in
- bytes, of the constant pool that GCC wrote immediately before this
- call.
-
- If no constant-pool epilogue is required, the usual case, you need
- not define this macro.
-
-`IS_ASM_LOGICAL_LINE_SEPARATOR (C)'
- Define this macro as a C expression which is nonzero if C is used
- as a logical line separator by the assembler.
-
- If you do not define this macro, the default is that only the
- character `;' is treated as a logical line separator.
-
- - Target Hook: const char * TARGET_ASM_OPEN_PAREN
- - Target Hook: const char * TARGET_ASM_CLOSE_PAREN
- These target hooks are C string constants, describing the syntax
- in the assembler for grouping arithmetic expressions. If not
- overridden, they default to normal parentheses, which is correct
- for most assemblers.
-
- These macros are provided by `real.h' for writing the definitions of
-`ASM_OUTPUT_DOUBLE' and the like:
-
-`REAL_VALUE_TO_TARGET_SINGLE (X, L)'
-`REAL_VALUE_TO_TARGET_DOUBLE (X, L)'
-`REAL_VALUE_TO_TARGET_LONG_DOUBLE (X, L)'
- These translate X, of type `REAL_VALUE_TYPE', to the target's
- floating point representation, and store its bit pattern in the
- array of `long int' whose address is L. The number of elements in
- the output array is determined by the size of the desired target
- floating point data type: 32 bits of it go in each `long int' array
- element. Each array element holds 32 bits of the result, even if
- `long int' is wider than 32 bits on the host machine.
-
- The array element values are designed so that you can print them
- out using `fprintf' in the order they should appear in the target
- machine's memory.
-
-`REAL_VALUE_TO_DECIMAL (X, FORMAT, STRING)'
- This macro converts X, of type `REAL_VALUE_TYPE', to a decimal
- number and stores it as a string into STRING. You must pass, as
- STRING, the address of a long enough block of space to hold the
- result.
-
- The argument FORMAT is a `printf'-specification that serves as a
- suggestion for how to format the output string.
-
-\1f
-File: gccint.info, Node: Uninitialized Data, Next: Label Output, Prev: Data Output, Up: Assembler Format
-
-Output of Uninitialized Variables
----------------------------------
-
- Each of the macros in this section is used to do the whole job of
-outputting a single uninitialized variable.
-
-`ASM_OUTPUT_COMMON (STREAM, NAME, SIZE, ROUNDED)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM the assembler definition of a common-label named NAME whose
- size is SIZE bytes. The variable ROUNDED is the size rounded up
- to whatever alignment the caller wants.
-
- Use the expression `assemble_name (STREAM, NAME)' to output the
- name itself; before and after that, output the additional
- assembler syntax for defining the name, and a newline.
-
- This macro controls how the assembler definitions of uninitialized
- common global variables are output.
-
-`ASM_OUTPUT_ALIGNED_COMMON (STREAM, NAME, SIZE, ALIGNMENT)'
- Like `ASM_OUTPUT_COMMON' except takes the required alignment as a
- separate, explicit argument. If you define this macro, it is used
- in place of `ASM_OUTPUT_COMMON', and gives you more flexibility in
- handling the required alignment of the variable. The alignment is
- specified as the number of bits.
-
-`ASM_OUTPUT_ALIGNED_DECL_COMMON (STREAM, DECL, NAME, SIZE, ALIGNMENT)'
- Like `ASM_OUTPUT_ALIGNED_COMMON' except that DECL of the variable
- to be output, if there is one, or `NULL_TREE' if there is no
- corresponding variable. If you define this macro, GCC will use it
- in place of both `ASM_OUTPUT_COMMON' and
- `ASM_OUTPUT_ALIGNED_COMMON'. Define this macro when you need to
- see the variable's decl in order to chose what to output.
-
-`ASM_OUTPUT_SHARED_COMMON (STREAM, NAME, SIZE, ROUNDED)'
- If defined, it is similar to `ASM_OUTPUT_COMMON', except that it
- is used when NAME is shared. If not defined, `ASM_OUTPUT_COMMON'
- will be used.
-
-`ASM_OUTPUT_BSS (STREAM, DECL, NAME, SIZE, ROUNDED)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM the assembler definition of uninitialized global DECL named
- NAME whose size is SIZE bytes. The variable ROUNDED is the size
- rounded up to whatever alignment the caller wants.
-
- Try to use function `asm_output_bss' defined in `varasm.c' when
- defining this macro. If unable, use the expression `assemble_name
- (STREAM, NAME)' to output the name itself; before and after that,
- output the additional assembler syntax for defining the name, and
- a newline.
-
- This macro controls how the assembler definitions of uninitialized
- global variables are output. This macro exists to properly
- support languages like C++ which do not have `common' data.
- However, this macro currently is not defined for all targets. If
- this macro and `ASM_OUTPUT_ALIGNED_BSS' are not defined then
- `ASM_OUTPUT_COMMON' or `ASM_OUTPUT_ALIGNED_COMMON' or
- `ASM_OUTPUT_ALIGNED_DECL_COMMON' is used.
-
-`ASM_OUTPUT_ALIGNED_BSS (STREAM, DECL, NAME, SIZE, ALIGNMENT)'
- Like `ASM_OUTPUT_BSS' except takes the required alignment as a
- separate, explicit argument. If you define this macro, it is used
- in place of `ASM_OUTPUT_BSS', and gives you more flexibility in
- handling the required alignment of the variable. The alignment is
- specified as the number of bits.
-
- Try to use function `asm_output_aligned_bss' defined in file
- `varasm.c' when defining this macro.
-
-`ASM_OUTPUT_SHARED_BSS (STREAM, DECL, NAME, SIZE, ROUNDED)'
- If defined, it is similar to `ASM_OUTPUT_BSS', except that it is
- used when NAME is shared. If not defined, `ASM_OUTPUT_BSS' will
- be used.
-
-`ASM_OUTPUT_LOCAL (STREAM, NAME, SIZE, ROUNDED)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM the assembler definition of a local-common-label named NAME
- whose size is SIZE bytes. The variable ROUNDED is the size
- rounded up to whatever alignment the caller wants.
-
- Use the expression `assemble_name (STREAM, NAME)' to output the
- name itself; before and after that, output the additional
- assembler syntax for defining the name, and a newline.
-
- This macro controls how the assembler definitions of uninitialized
- static variables are output.
-
-`ASM_OUTPUT_ALIGNED_LOCAL (STREAM, NAME, SIZE, ALIGNMENT)'
- Like `ASM_OUTPUT_LOCAL' except takes the required alignment as a
- separate, explicit argument. If you define this macro, it is used
- in place of `ASM_OUTPUT_LOCAL', and gives you more flexibility in
- handling the required alignment of the variable. The alignment is
- specified as the number of bits.
-
-`ASM_OUTPUT_ALIGNED_DECL_LOCAL (STREAM, DECL, NAME, SIZE, ALIGNMENT)'
- Like `ASM_OUTPUT_ALIGNED_DECL' except that DECL of the variable to
- be output, if there is one, or `NULL_TREE' if there is no
- corresponding variable. If you define this macro, GCC will use it
- in place of both `ASM_OUTPUT_DECL' and `ASM_OUTPUT_ALIGNED_DECL'.
- Define this macro when you need to see the variable's decl in
- order to chose what to output.
-
-`ASM_OUTPUT_SHARED_LOCAL (STREAM, NAME, SIZE, ROUNDED)'
- If defined, it is similar to `ASM_OUTPUT_LOCAL', except that it is
- used when NAME is shared. If not defined, `ASM_OUTPUT_LOCAL' will
- be used.
-
-\1f
-File: gccint.info, Node: Label Output, Next: Initialization, Prev: Uninitialized Data, Up: Assembler Format
-
-Output and Generation of Labels
--------------------------------
-
- This is about outputting labels.
-
-`ASM_OUTPUT_LABEL (STREAM, NAME)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM the assembler definition of a label named NAME. Use the
- expression `assemble_name (STREAM, NAME)' to output the name
- itself; before and after that, output the additional assembler
- syntax for defining the name, and a newline.
-
-`ASM_DECLARE_FUNCTION_NAME (STREAM, NAME, DECL)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM any text necessary for declaring the name NAME of a
- function which is being defined. This macro is responsible for
- outputting the label definition (perhaps using
- `ASM_OUTPUT_LABEL'). The argument DECL is the `FUNCTION_DECL'
- tree node representing the function.
-
- If this macro is not defined, then the function name is defined in
- the usual manner as a label (by means of `ASM_OUTPUT_LABEL').
-
-`ASM_DECLARE_FUNCTION_SIZE (STREAM, NAME, DECL)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM any text necessary for declaring the size of a function
- which is being defined. The argument NAME is the name of the
- function. The argument DECL is the `FUNCTION_DECL' tree node
- representing the function.
-
- If this macro is not defined, then the function size is not
- defined.
-
-`ASM_DECLARE_OBJECT_NAME (STREAM, NAME, DECL)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM any text necessary for declaring the name NAME of an
- initialized variable which is being defined. This macro must
- output the label definition (perhaps using `ASM_OUTPUT_LABEL').
- The argument DECL is the `VAR_DECL' tree node representing the
- variable.
-
- If this macro is not defined, then the variable name is defined in
- the usual manner as a label (by means of `ASM_OUTPUT_LABEL').
-
-`ASM_DECLARE_REGISTER_GLOBAL (STREAM, DECL, REGNO, NAME)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM any text necessary for claiming a register REGNO for a
- global variable DECL with name NAME.
-
- If you don't define this macro, that is equivalent to defining it
- to do nothing.
-
-`ASM_FINISH_DECLARE_OBJECT (STREAM, DECL, TOPLEVEL, ATEND)'
- A C statement (sans semicolon) to finish up declaring a variable
- name once the compiler has processed its initializer fully and
- thus has had a chance to determine the size of an array when
- controlled by an initializer. This is used on systems where it's
- necessary to declare something about the size of the object.
-
- If you don't define this macro, that is equivalent to defining it
- to do nothing.
-
-`ASM_GLOBALIZE_LABEL (STREAM, NAME)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM some commands that will make the label NAME global; that
- is, available for reference from other files. Use the expression
- `assemble_name (STREAM, NAME)' to output the name itself; before
- and after that, output the additional assembler syntax for making
- that name global, and a newline.
-
-`ASM_WEAKEN_LABEL (STREAM, NAME)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM some commands that will make the label NAME weak; that is,
- available for reference from other files but only used if no other
- definition is available. Use the expression `assemble_name
- (STREAM, NAME)' to output the name itself; before and after that,
- output the additional assembler syntax for making that name weak,
- and a newline.
-
- If you don't define this macro or `ASM_WEAKEN_DECL', GCC will not
- support weak symbols and you should not define the `SUPPORTS_WEAK'
- macro.
-
-`ASM_WEAKEN_DECL (STREAM, DECL, NAME, VALUE)'
- Combines (and replaces) the function of `ASM_WEAKEN_LABEL' and
- `ASM_OUTPUT_WEAK_ALIAS', allowing access to the associated function
- or variable decl. If VALUE is not `NULL', this C statement should
- output to the stdio stream STREAM assembler code which defines
- (equates) the weak symbol NAME to have the value VALUE. If VALUE
- is `NULL', it should output commands to make NAME weak.
-
-`SUPPORTS_WEAK'
- A C expression which evaluates to true if the target supports weak
- symbols.
-
- If you don't define this macro, `defaults.h' provides a default
- definition. If either `ASM_WEAKEN_LABEL' or `ASM_WEAKEN_DECL' is
- defined, the default definition is `1'; otherwise, it is `0'.
- Define this macro if you want to control weak symbol support with
- a compiler flag such as `-melf'.
-
-`MAKE_DECL_ONE_ONLY'
- A C statement (sans semicolon) to mark DECL to be emitted as a
- public symbol such that extra copies in multiple translation units
- will be discarded by the linker. Define this macro if your object
- file format provides support for this concept, such as the `COMDAT'
- section flags in the Microsoft Windows PE/COFF format, and this
- support requires changes to DECL, such as putting it in a separate
- section.
-
-`SUPPORTS_ONE_ONLY'
- A C expression which evaluates to true if the target supports
- one-only semantics.
-
- If you don't define this macro, `varasm.c' provides a default
- definition. If `MAKE_DECL_ONE_ONLY' is defined, the default
- definition is `1'; otherwise, it is `0'. Define this macro if you
- want to control one-only symbol support with a compiler flag, or if
- setting the `DECL_ONE_ONLY' flag is enough to mark a declaration to
- be emitted as one-only.
-
-`ASM_OUTPUT_EXTERNAL (STREAM, DECL, NAME)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM any text necessary for declaring the name of an external
- symbol named NAME which is referenced in this compilation but not
- defined. The value of DECL is the tree node for the declaration.
-
- This macro need not be defined if it does not need to output
- anything. The GNU assembler and most Unix assemblers don't
- require anything.
-
-`ASM_OUTPUT_EXTERNAL_LIBCALL (STREAM, SYMREF)'
- A C statement (sans semicolon) to output on STREAM an assembler
- pseudo-op to declare a library function name external. The name
- of the library function is given by SYMREF, which has type `rtx'
- and is a `symbol_ref'.
-
- This macro need not be defined if it does not need to output
- anything. The GNU assembler and most Unix assemblers don't
- require anything.
-
-`ASM_OUTPUT_LABELREF (STREAM, NAME)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM a reference in assembler syntax to a label named NAME.
- This should add `_' to the front of the name, if that is customary
- on your operating system, as it is in most Berkeley Unix systems.
- This macro is used in `assemble_name'.
-
-`ASM_OUTPUT_SYMBOL_REF (STREAM, SYM)'
- A C statement (sans semicolon) to output a reference to
- `SYMBOL_REF' SYM. If not defined, `assemble_name' will be used to
- output the name of the symbol. This macro may be used to modify
- the way a symbol is referenced depending on information encoded by
- `ENCODE_SECTION_INFO'.
-
-`ASM_OUTPUT_LABEL_REF (STREAM, BUF)'
- A C statement (sans semicolon) to output a reference to BUF, the
- result of ASM_GENERATE_INTERNAL_LABEL. If not defined,
- `assemble_name' will be used to output the name of the symbol.
- This macro is not used by `output_asm_label', or the `%l'
- specifier that calls it; the intention is that this macro should
- be set when it is necessary to output a label differently when its
- address is being taken.
-
-`ASM_OUTPUT_INTERNAL_LABEL (STREAM, PREFIX, NUM)'
- A C statement to output to the stdio stream STREAM a label whose
- name is made from the string PREFIX and the number NUM.
-
- It is absolutely essential that these labels be distinct from the
- labels used for user-level functions and variables. Otherwise,
- certain programs will have name conflicts with internal labels.
-
- It is desirable to exclude internal labels from the symbol table
- of the object file. Most assemblers have a naming convention for
- labels that should be excluded; on many systems, the letter `L' at
- the beginning of a label has this effect. You should find out what
- convention your system uses, and follow it.
-
- The usual definition of this macro is as follows:
-
- fprintf (STREAM, "L%s%d:\n", PREFIX, NUM)
-
-`ASM_OUTPUT_DEBUG_LABEL (STREAM, PREFIX, NUM)'
- A C statement to output to the stdio stream STREAM a debug info
- label whose name is made from the string PREFIX and the number
- NUM. This is useful for VLIW targets, where debug info labels may
- need to be treated differently than branch target labels. On some
- systems, branch target labels must be at the beginning of
- instruction bundles, but debug info labels can occur in the middle
- of instruction bundles.
-
- If this macro is not defined, then `ASM_OUTPUT_INTERNAL_LABEL'
- will be used.
-
-`ASM_OUTPUT_ALTERNATE_LABEL_NAME (STREAM, STRING)'
- A C statement to output to the stdio stream STREAM the string
- STRING.
-
- The default definition of this macro is as follows:
-
- fprintf (STREAM, "%s:\n", LABEL_ALTERNATE_NAME (INSN))
-
-`ASM_GENERATE_INTERNAL_LABEL (STRING, PREFIX, NUM)'
- A C statement to store into the string STRING a label whose name
- is made from the string PREFIX and the number NUM.
-
- This string, when output subsequently by `assemble_name', should
- produce the output that `ASM_OUTPUT_INTERNAL_LABEL' would produce
- with the same PREFIX and NUM.
-
- If the string begins with `*', then `assemble_name' will output
- the rest of the string unchanged. It is often convenient for
- `ASM_GENERATE_INTERNAL_LABEL' to use `*' in this way. If the
- string doesn't start with `*', then `ASM_OUTPUT_LABELREF' gets to
- output the string, and may change it. (Of course,
- `ASM_OUTPUT_LABELREF' is also part of your machine description, so
- you should know what it does on your machine.)
-
-`ASM_FORMAT_PRIVATE_NAME (OUTVAR, NAME, NUMBER)'
- A C expression to assign to OUTVAR (which is a variable of type
- `char *') a newly allocated string made from the string NAME and
- the number NUMBER, with some suitable punctuation added. Use
- `alloca' to get space for the string.
-
- The string will be used as an argument to `ASM_OUTPUT_LABELREF' to
- produce an assembler label for an internal static variable whose
- name is NAME. Therefore, the string must be such as to result in
- valid assembler code. The argument NUMBER is different each time
- this macro is executed; it prevents conflicts between
- similarly-named internal static variables in different scopes.
-
- Ideally this string should not be a valid C identifier, to prevent
- any conflict with the user's own symbols. Most assemblers allow
- periods or percent signs in assembler symbols; putting at least
- one of these between the name and the number will suffice.
-
-`ASM_OUTPUT_DEF (STREAM, NAME, VALUE)'
- A C statement to output to the stdio stream STREAM assembler code
- which defines (equates) the symbol NAME to have the value VALUE.
-
- If `SET_ASM_OP' is defined, a default definition is provided which
- is correct for most systems.
-
-`ASM_OUTPUT_DEF_FROM_DECLS (STREAM, DECL_OF_NAME, DECL_OF_VALUE)'
- A C statement to output to the stdio stream STREAM assembler code
- which defines (equates) the symbol whose tree node is DECL_OF_NAME
- to have the value of the tree node DECL_OF_VALUE. This macro will
- be used in preference to `ASM_OUTPUT_DEF' if it is defined and if
- the tree nodes are available.
-
-`ASM_OUTPUT_DEFINE_LABEL_DIFFERENCE_SYMBOL (STREAM, SYMBOL, HIGH, LOW)'
- A C statement to output to the stdio stream STREAM assembler code
- which defines (equates) the symbol SYMBOL to have a value equal to
- the difference of the two symbols HIGH and LOW, i.e. HIGH minus
- LOW. GCC guarantees that the symbols HIGH and LOW are already
- known by the assembler so that the difference resolves into a
- constant.
-
- If `SET_ASM_OP' is defined, a default definition is provided which
- is correct for most systems.
-
-`ASM_OUTPUT_WEAK_ALIAS (STREAM, NAME, VALUE)'
- A C statement to output to the stdio stream STREAM assembler code
- which defines (equates) the weak symbol NAME to have the value
- VALUE. If VALUE is `NULL', it defines NAME as an undefined weak
- symbol.
-
- Define this macro if the target only supports weak aliases; define
- `ASM_OUTPUT_DEF' instead if possible.
-
-`OBJC_GEN_METHOD_LABEL (BUF, IS_INST, CLASS_NAME, CAT_NAME, SEL_NAME)'
- Define this macro to override the default assembler names used for
- Objective-C methods.
-
- The default name is a unique method number followed by the name of
- the class (e.g. `_1_Foo'). For methods in categories, the name of
- the category is also included in the assembler name (e.g.
- `_1_Foo_Bar').
-
- These names are safe on most systems, but make debugging difficult
- since the method's selector is not present in the name.
- Therefore, particular systems define other ways of computing names.
-
- BUF is an expression of type `char *' which gives you a buffer in
- which to store the name; its length is as long as CLASS_NAME,
- CAT_NAME and SEL_NAME put together, plus 50 characters extra.
-
- The argument IS_INST specifies whether the method is an instance
- method or a class method; CLASS_NAME is the name of the class;
- CAT_NAME is the name of the category (or `NULL' if the method is
- not in a category); and SEL_NAME is the name of the selector.
-
- On systems where the assembler can handle quoted names, you can
- use this macro to provide more human-readable names.
-
-`ASM_DECLARE_CLASS_REFERENCE (STREAM, NAME)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM commands to declare that the label NAME is an Objective-C
- class reference. This is only needed for targets whose linkers
- have special support for NeXT-style runtimes.
-
-`ASM_DECLARE_UNRESOLVED_REFERENCE (STREAM, NAME)'
- A C statement (sans semicolon) to output to the stdio stream
- STREAM commands to declare that the label NAME is an unresolved
- Objective-C class reference. This is only needed for targets
- whose linkers have special support for NeXT-style runtimes.
-
-\1f
-File: gccint.info, Node: Initialization, Next: Macros for Initialization, Prev: Label Output, Up: Assembler Format
-
-How Initialization Functions Are Handled
-----------------------------------------
-
- The compiled code for certain languages includes "constructors"
-(also called "initialization routines")--functions to initialize data
-in the program when the program is started. These functions need to be
-called before the program is "started"--that is to say, before `main'
-is called.
-
- Compiling some languages generates "destructors" (also called
-"termination routines") that should be called when the program
-terminates.
-
- To make the initialization and termination functions work, the
-compiler must output something in the assembler code to cause those
-functions to be called at the appropriate time. When you port the
-compiler to a new system, you need to specify how to do this.
-
- There are two major ways that GCC currently supports the execution of
-initialization and termination functions. Each way has two variants.
-Much of the structure is common to all four variations.
-
- The linker must build two lists of these functions--a list of
-initialization functions, called `__CTOR_LIST__', and a list of
-termination functions, called `__DTOR_LIST__'.
-
- Each list always begins with an ignored function pointer (which may
-hold 0, -1, or a count of the function pointers after it, depending on
-the environment). This is followed by a series of zero or more function
-pointers to constructors (or destructors), followed by a function
-pointer containing zero.
-
- Depending on the operating system and its executable file format,
-either `crtstuff.c' or `libgcc2.c' traverses these lists at startup
-time and exit time. Constructors are called in reverse order of the
-list; destructors in forward order.
-
- The best way to handle static constructors works only for object file
-formats which provide arbitrarily-named sections. A section is set
-aside for a list of constructors, and another for a list of destructors.
-Traditionally these are called `.ctors' and `.dtors'. Each object file
-that defines an initialization function also puts a word in the
-constructor section to point to that function. The linker accumulates
-all these words into one contiguous `.ctors' section. Termination
-functions are handled similarly.
-
- This method will be chosen as the default by `target-def.h' if
-`TARGET_ASM_NAMED_SECTION' is defined. A target that does not support
-arbitrary sections, but does support special designated constructor and
-destructor sections may define `CTORS_SECTION_ASM_OP' and
-`DTORS_SECTION_ASM_OP' to achieve the same effect.
-
- When arbitrary sections are available, there are two variants,
-depending upon how the code in `crtstuff.c' is called. On systems that
-support a ".init" section which is executed at program startup, parts
-of `crtstuff.c' are compiled into that section. The program is linked
-by the `gcc' driver like this:
-
- ld -o OUTPUT_FILE crti.o crtbegin.o ... -lgcc crtend.o crtn.o
-
- The prologue of a function (`__init') appears in the `.init' section
-of `crti.o'; the epilogue appears in `crtn.o'. Likewise for the
-function `__fini' in the ".fini" section. Normally these files are
-provided by the operating system or by the GNU C library, but are
-provided by GCC for a few targets.
-
- The objects `crtbegin.o' and `crtend.o' are (for most targets)
-compiled from `crtstuff.c'. They contain, among other things, code
-fragments within the `.init' and `.fini' sections that branch to
-routines in the `.text' section. The linker will pull all parts of a
-section together, which results in a complete `__init' function that
-invokes the routines we need at startup.
-
- To use this variant, you must define the `INIT_SECTION_ASM_OP' macro
-properly.
-
- If no init section is available, when GCC compiles any function
-called `main' (or more accurately, any function designated as a program
-entry point by the language front end calling `expand_main_function'),
-it inserts a procedure call to `__main' as the first executable code
-after the function prologue. The `__main' function is defined in
-`libgcc2.c' and runs the global constructors.
-
- In file formats that don't support arbitrary sections, there are
-again two variants. In the simplest variant, the GNU linker (GNU `ld')
-and an `a.out' format must be used. In this case,
-`TARGET_ASM_CONSTRUCTOR' is defined to produce a `.stabs' entry of type
-`N_SETT', referencing the name `__CTOR_LIST__', and with the address of
-the void function containing the initialization code as its value. The
-GNU linker recognizes this as a request to add the value to a "set";
-the values are accumulated, and are eventually placed in the executable
-as a vector in the format described above, with a leading (ignored)
-count and a trailing zero element. `TARGET_ASM_DESTRUCTOR' is handled
-similarly. Since no init section is available, the absence of
-`INIT_SECTION_ASM_OP' causes the compilation of `main' to call `__main'
-as above, starting the initialization process.
-
- The last variant uses neither arbitrary sections nor the GNU linker.
-This is preferable when you want to do dynamic linking and when using
-file formats which the GNU linker does not support, such as `ECOFF'. In
-this case, `TARGET_HAVE_CTORS_DTORS' is false, initialization and
-termination functions are recognized simply by their names. This
-requires an extra program in the linkage step, called `collect2'. This
-program pretends to be the linker, for use with GCC; it does its job by
-running the ordinary linker, but also arranges to include the vectors of
-initialization and termination functions. These functions are called
-via `__main' as described above. In order to use this method,
-`use_collect2' must be defined in the target in `config.gcc'.
-
- The following section describes the specific macros that control and
-customize the handling of initialization and termination functions.
-
-\1f
-File: gccint.info, Node: Macros for Initialization, Next: Instruction Output, Prev: Initialization, Up: Assembler Format
-
-Macros Controlling Initialization Routines
-------------------------------------------
-
- Here are the macros that control how the compiler handles
-initialization and termination functions:
-
-`INIT_SECTION_ASM_OP'
- If defined, a C string constant, including spacing, for the
- assembler operation to identify the following data as
- initialization code. If not defined, GCC will assume such a
- section does not exist. When you are using special sections for
- initialization and termination functions, this macro also controls
- how `crtstuff.c' and `libgcc2.c' arrange to run the initialization
- functions.
-
-`HAS_INIT_SECTION'
- If defined, `main' will not call `__main' as described above.
- This macro should be defined for systems that control start-up code
- on a symbol-by-symbol basis, such as OSF/1, and should not be
- defined explicitly for systems that support `INIT_SECTION_ASM_OP'.
-
-`LD_INIT_SWITCH'
- If defined, a C string constant for a switch that tells the linker
- that the following symbol is an initialization routine.
-
-`LD_FINI_SWITCH'
- If defined, a C string constant for a switch that tells the linker
- that the following symbol is a finalization routine.
-
-`COLLECT_SHARED_INIT_FUNC (STREAM, FUNC)'
- If defined, a C statement that will write a function that can be
- automatically called when a shared library is loaded. The function
- should call FUNC, which takes no arguments. If not defined, and
- the object format requires an explicit initialization function,
- then a function called `_GLOBAL__DI' will be generated.
-
- This function and the following one are used by collect2 when
- linking a shared library that needs constructors or destructors,
- or has DWARF2 exception tables embedded in the code.
-
-`COLLECT_SHARED_FINI_FUNC (STREAM, FUNC)'
- If defined, a C statement that will write a function that can be
- automatically called when a shared library is unloaded. The
- function should call FUNC, which takes no arguments. If not
- defined, and the object format requires an explicit finalization
- function, then a function called `_GLOBAL__DD' will be generated.
-
-`INVOKE__main'
- If defined, `main' will call `__main' despite the presence of
- `INIT_SECTION_ASM_OP'. This macro should be defined for systems
- where the init section is not actually run automatically, but is
- still useful for collecting the lists of constructors and
- destructors.
-
-`SUPPORTS_INIT_PRIORITY'
- If nonzero, the C++ `init_priority' attribute is supported and the
- compiler should emit instructions to control the order of
- initialization of objects. If zero, the compiler will issue an
- error message upon encountering an `init_priority' attribute.
-
- - Target Hook: bool TARGET_HAVE_CTORS_DTORS
- This value is true if the target supports some "native" method of
- collecting constructors and destructors to be run at startup and
- exit. It is false if we must use `collect2'.
-
- - Target Hook: void TARGET_ASM_CONSTRUCTOR (rtx SYMBOL, int PRIORITY)
- If defined, a function that outputs assembler code to arrange to
- call the function referenced by SYMBOL at initialization time.
-
- Assume that SYMBOL is a `SYMBOL_REF' for a function taking no
- arguments and with no return value. If the target supports
- initialization priorities, PRIORITY is a value between 0 and
- `MAX_INIT_PRIORITY'; otherwise it must be `DEFAULT_INIT_PRIORITY'.
-
- If this macro is not defined by the target, a suitable default will
- be chosen if (1) the target supports arbitrary section names, (2)
- the target defines `CTORS_SECTION_ASM_OP', or (3) `USE_COLLECT2'
- is not defined.
-
- - Target Hook: void TARGET_ASM_DESTRUCTOR (rtx SYMBOL, int PRIORITY)
- This is like `TARGET_ASM_CONSTRUCTOR' but used for termination
- functions rather than initialization functions.
-
- If `TARGET_HAVE_CTORS_DTORS' is true, the initialization routine
-generated for the generated object file will have static linkage.
-
- If your system uses `collect2' as the means of processing
-constructors, then that program normally uses `nm' to scan an object
-file for constructor functions to be called.
-
- On certain kinds of systems, you can define these macros to make
-`collect2' work faster (and, in some cases, make it work at all):
-
-`OBJECT_FORMAT_COFF'
- Define this macro if the system uses COFF (Common Object File
- Format) object files, so that `collect2' can assume this format
- and scan object files directly for dynamic constructor/destructor
- functions.
-
-`OBJECT_FORMAT_ROSE'
- Define this macro if the system uses ROSE format object files, so
- that `collect2' can assume this format and scan object files
- directly for dynamic constructor/destructor functions.
-
- These macros are effective only in a native compiler; `collect2' as
- part of a cross compiler always uses `nm' for the target machine.
-
-`REAL_NM_FILE_NAME'
- Define this macro as a C string constant containing the file name
- to use to execute `nm'. The default is to search the path
- normally for `nm'.
-
- If your system supports shared libraries and has a program to list
- the dynamic dependencies of a given library or executable, you can
- define these macros to enable support for running initialization
- and termination functions in shared libraries:
-
-`LDD_SUFFIX'
- Define this macro to a C string constant containing the name of
- the program which lists dynamic dependencies, like `"ldd"' under
- SunOS 4.
-
-`PARSE_LDD_OUTPUT (PTR)'
- Define this macro to be C code that extracts filenames from the
- output of the program denoted by `LDD_SUFFIX'. PTR is a variable
- of type `char *' that points to the beginning of a line of output
- from `LDD_SUFFIX'. If the line lists a dynamic dependency, the
- code must advance PTR to the beginning of the filename on that
- line. Otherwise, it must set PTR to `NULL'.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Instruction Output, Next: Dispatch Tables, Prev: Macros for Initialization, Up: Assembler Format
-
-Output of Assembler Instructions
---------------------------------
-
- This describes assembler instruction output.
-
-`REGISTER_NAMES'
- A C initializer containing the assembler's names for the machine
- registers, each one as a C string constant. This is what
- translates register numbers in the compiler into assembler
- language.
-
-`ADDITIONAL_REGISTER_NAMES'
- If defined, a C initializer for an array of structures containing
- a name and a register number. This macro defines additional names
- for hard registers, thus allowing the `asm' option in declarations
- to refer to registers using alternate names.
-
-`ASM_OUTPUT_OPCODE (STREAM, PTR)'
- Define this macro if you are using an unusual assembler that
- requires different names for the machine instructions.
-
- The definition is a C statement or statements which output an
- assembler instruction opcode to the stdio stream STREAM. The
- macro-operand PTR is a variable of type `char *' which points to
- the opcode name in its "internal" form--the form that is written
- in the machine description. The definition should output the
- opcode name to STREAM, performing any translation you desire, and
- increment the variable PTR to point at the end of the opcode so
- that it will not be output twice.
-
- In fact, your macro definition may process less than the entire
- opcode name, or more than the opcode name; but if you want to
- process text that includes `%'-sequences to substitute operands,
- you must take care of the substitution yourself. Just be sure to
- increment PTR over whatever text should not be output normally.
-
- If you need to look at the operand values, they can be found as the
- elements of `recog_data.operand'.
-
- If the macro definition does nothing, the instruction is output in
- the usual way.
-
-`FINAL_PRESCAN_INSN (INSN, OPVEC, NOPERANDS)'
- If defined, a C statement to be executed just prior to the output
- of assembler code for INSN, to modify the extracted operands so
- they will be output differently.
-
- Here the argument OPVEC is the vector containing the operands
- extracted from INSN, and NOPERANDS is the number of elements of
- the vector which contain meaningful data for this insn. The
- contents of this vector are what will be used to convert the insn
- template into assembler code, so you can change the assembler
- output by changing the contents of the vector.
-
- This macro is useful when various assembler syntaxes share a single
- file of instruction patterns; by defining this macro differently,
- you can cause a large class of instructions to be output
- differently (such as with rearranged operands). Naturally,
- variations in assembler syntax affecting individual insn patterns
- ought to be handled by writing conditional output routines in
- those patterns.
-
- If this macro is not defined, it is equivalent to a null statement.
-
-`FINAL_PRESCAN_LABEL'
- If defined, `FINAL_PRESCAN_INSN' will be called on each
- `CODE_LABEL'. In that case, OPVEC will be a null pointer and
- NOPERANDS will be zero.
-
-`PRINT_OPERAND (STREAM, X, CODE)'
- A C compound statement to output to stdio stream STREAM the
- assembler syntax for an instruction operand X. X is an RTL
- expression.
-
- CODE is a value that can be used to specify one of several ways of
- printing the operand. It is used when identical operands must be
- printed differently depending on the context. CODE comes from the
- `%' specification that was used to request printing of the
- operand. If the specification was just `%DIGIT' then CODE is 0;
- if the specification was `%LTR DIGIT' then CODE is the ASCII code
- for LTR.
-
- If X is a register, this macro should print the register's name.
- The names can be found in an array `reg_names' whose type is `char
- *[]'. `reg_names' is initialized from `REGISTER_NAMES'.
-
- When the machine description has a specification `%PUNCT' (a `%'
- followed by a punctuation character), this macro is called with a
- null pointer for X and the punctuation character for CODE.
-
-`PRINT_OPERAND_PUNCT_VALID_P (CODE)'
- A C expression which evaluates to true if CODE is a valid
- punctuation character for use in the `PRINT_OPERAND' macro. If
- `PRINT_OPERAND_PUNCT_VALID_P' is not defined, it means that no
- punctuation characters (except for the standard one, `%') are used
- in this way.
-
-`PRINT_OPERAND_ADDRESS (STREAM, X)'
- A C compound statement to output to stdio stream STREAM the
- assembler syntax for an instruction operand that is a memory
- reference whose address is X. X is an RTL expression.
-
- On some machines, the syntax for a symbolic address depends on the
- section that the address refers to. On these machines, define the
- macro `ENCODE_SECTION_INFO' to store the information into the
- `symbol_ref', and then check for it here. *Note Assembler
- Format::.
-
-`DBR_OUTPUT_SEQEND(FILE)'
- A C statement, to be executed after all slot-filler instructions
- have been output. If necessary, call `dbr_sequence_length' to
- determine the number of slots filled in a sequence (zero if not
- currently outputting a sequence), to decide how many no-ops to
- output, or whatever.
-
- Don't define this macro if it has nothing to do, but it is helpful
- in reading assembly output if the extent of the delay sequence is
- made explicit (e.g. with white space).
-
- Note that output routines for instructions with delay slots must be
- prepared to deal with not being output as part of a sequence (i.e.
- when the scheduling pass is not run, or when no slot fillers could
- be found.) The variable `final_sequence' is null when not
- processing a sequence, otherwise it contains the `sequence' rtx
- being output.
-
-`REGISTER_PREFIX'
-`LOCAL_LABEL_PREFIX'
-`USER_LABEL_PREFIX'
-`IMMEDIATE_PREFIX'
- If defined, C string expressions to be used for the `%R', `%L',
- `%U', and `%I' options of `asm_fprintf' (see `final.c'). These
- are useful when a single `md' file must support multiple assembler
- formats. In that case, the various `tm.h' files can define these
- macros differently.
-
-`ASM_FPRINTF_EXTENSIONS(FILE, ARGPTR, FORMAT)'
- If defined this macro should expand to a series of `case'
- statements which will be parsed inside the `switch' statement of
- the `asm_fprintf' function. This allows targets to define extra
- printf formats which may useful when generating their assembler
- statements. Note that upper case letters are reserved for future
- generic extensions to asm_fprintf, and so are not available to
- target specific code. The output file is given by the parameter
- FILE. The varargs input pointer is ARGPTR and the rest of the
- format string, starting the character after the one that is being
- switched upon, is pointed to by FORMAT.
-
-`ASSEMBLER_DIALECT'
- If your target supports multiple dialects of assembler language
- (such as different opcodes), define this macro as a C expression
- that gives the numeric index of the assembler language dialect to
- use, with zero as the first variant.
-
- If this macro is defined, you may use constructs of the form
- `{option0|option1|option2...}'
-
- in the output templates of patterns (*note Output Template::) or
- in the first argument of `asm_fprintf'. This construct outputs
- `option0', `option1', `option2', etc., if the value of
- `ASSEMBLER_DIALECT' is zero, one, two, etc. Any special characters
- within these strings retain their usual meaning. If there are
- fewer alternatives within the braces than the value of
- `ASSEMBLER_DIALECT', the construct outputs nothing.
-
- If you do not define this macro, the characters `{', `|' and `}'
- do not have any special meaning when used in templates or operands
- to `asm_fprintf'.
-
- Define the macros `REGISTER_PREFIX', `LOCAL_LABEL_PREFIX',
- `USER_LABEL_PREFIX' and `IMMEDIATE_PREFIX' if you can express the
- variations in assembler language syntax with that mechanism.
- Define `ASSEMBLER_DIALECT' and use the `{option0|option1}' syntax
- if the syntax variant are larger and involve such things as
- different opcodes or operand order.
-
-`ASM_OUTPUT_REG_PUSH (STREAM, REGNO)'
- A C expression to output to STREAM some assembler code which will
- push hard register number REGNO onto the stack. The code need not
- be optimal, since this macro is used only when profiling.
-
-`ASM_OUTPUT_REG_POP (STREAM, REGNO)'
- A C expression to output to STREAM some assembler code which will
- pop hard register number REGNO off of the stack. The code need
- not be optimal, since this macro is used only when profiling.
-
-\1f
-File: gccint.info, Node: Dispatch Tables, Next: Exception Region Output, Prev: Instruction Output, Up: Assembler Format
-
-Output of Dispatch Tables
--------------------------
-
- This concerns dispatch tables.
-
-`ASM_OUTPUT_ADDR_DIFF_ELT (STREAM, BODY, VALUE, REL)'
- A C statement to output to the stdio stream STREAM an assembler
- pseudo-instruction to generate a difference between two labels.
- VALUE and REL are the numbers of two internal labels. The
- definitions of these labels are output using
- `ASM_OUTPUT_INTERNAL_LABEL', and they must be printed in the same
- way here. For example,
-
- fprintf (STREAM, "\t.word L%d-L%d\n",
- VALUE, REL)
-
- You must provide this macro on machines where the addresses in a
- dispatch table are relative to the table's own address. If
- defined, GCC will also use this macro on all machines when
- producing PIC. BODY is the body of the `ADDR_DIFF_VEC'; it is
- provided so that the mode and flags can be read.
-
-`ASM_OUTPUT_ADDR_VEC_ELT (STREAM, VALUE)'
- This macro should be provided on machines where the addresses in a
- dispatch table are absolute.
-
- The definition should be a C statement to output to the stdio
- stream STREAM an assembler pseudo-instruction to generate a
- reference to a label. VALUE is the number of an internal label
- whose definition is output using `ASM_OUTPUT_INTERNAL_LABEL'. For
- example,
-
- fprintf (STREAM, "\t.word L%d\n", VALUE)
-
-`ASM_OUTPUT_CASE_LABEL (STREAM, PREFIX, NUM, TABLE)'
- Define this if the label before a jump-table needs to be output
- specially. The first three arguments are the same as for
- `ASM_OUTPUT_INTERNAL_LABEL'; the fourth argument is the jump-table
- which follows (a `jump_insn' containing an `addr_vec' or
- `addr_diff_vec').
-
- This feature is used on system V to output a `swbeg' statement for
- the table.
-
- If this macro is not defined, these labels are output with
- `ASM_OUTPUT_INTERNAL_LABEL'.
-
-`ASM_OUTPUT_CASE_END (STREAM, NUM, TABLE)'
- Define this if something special must be output at the end of a
- jump-table. The definition should be a C statement to be executed
- after the assembler code for the table is written. It should write
- the appropriate code to stdio stream STREAM. The argument TABLE
- is the jump-table insn, and NUM is the label-number of the
- preceding label.
-
- If this macro is not defined, nothing special is output at the end
- of the jump-table.
-
-\1f
-File: gccint.info, Node: Exception Region Output, Next: Alignment Output, Prev: Dispatch Tables, Up: Assembler Format
-
-Assembler Commands for Exception Regions
-----------------------------------------
-
- This describes commands marking the start and the end of an exception
-region.
-
-`EH_FRAME_SECTION_NAME'
- If defined, a C string constant for the name of the section
- containing exception handling frame unwind information. If not
- defined, GCC will provide a default definition if the target
- supports named sections. `crtstuff.c' uses this macro to switch
- to the appropriate section.
-
- You should define this symbol if your target supports DWARF 2 frame
- unwind information and the default definition does not work.
-
-`EH_FRAME_IN_DATA_SECTION'
- If defined, DWARF 2 frame unwind information will be placed in the
- data section even though the target supports named sections. This
- might be necessary, for instance, if the system linker does garbage
- collection and sections cannot be marked as not to be collected.
-
- Do not define this macro unless `TARGET_ASM_NAMED_SECTION' is also
- defined.
-
-`MASK_RETURN_ADDR'
- An rtx used to mask the return address found via
- `RETURN_ADDR_RTX', so that it does not contain any extraneous set
- bits in it.
-
-`DWARF2_UNWIND_INFO'
- Define this macro to 0 if your target supports DWARF 2 frame unwind
- information, but it does not yet work with exception handling.
- Otherwise, if your target supports this information (if it defines
- `INCOMING_RETURN_ADDR_RTX' and either `UNALIGNED_INT_ASM_OP' or
- `OBJECT_FORMAT_ELF'), GCC will provide a default definition of 1.
-
- If this macro is defined to 1, the DWARF 2 unwinder will be the
- default exception handling mechanism; otherwise,
- `setjmp'/`longjmp' will be used by default.
-
- If this macro is defined to anything, the DWARF 2 unwinder will be
- used instead of inline unwinders and `__unwind_function' in the
- non-`setjmp' case.
-
-`DWARF_CIE_DATA_ALIGNMENT'
- This macro need only be defined if the target might save registers
- in the function prologue at an offset to the stack pointer that is
- not aligned to `UNITS_PER_WORD'. The definition should be the
- negative minimum alignment if `STACK_GROWS_DOWNWARD' is defined,
- and the positive minimum alignment otherwise. *Note SDB and
- DWARF::. Only applicable if the target supports DWARF 2 frame
- unwind information.
-
-
- - Target Hook: void TARGET_ASM_EXCEPTION_SECTION ()
- If defined, a function that switches to the section in which the
- main exception table is to be placed (*note Sections::). The
- default is a function that switches to a section named
- `.gcc_except_table' on machines that support named sections via
- `TARGET_ASM_NAMED_SECTION', otherwise if `-fpic' or `-fPIC' is in
- effect, the `data_section', otherwise the `readonly_data_section'.
-
- - Target Hook: void TARGET_ASM_EH_FRAME_SECTION ()
- If defined, a function that switches to the section in which the
- DWARF 2 frame unwind information to be placed (*note Sections::).
- The default is a function that outputs a standard GAS section
- directive, if `EH_FRAME_SECTION_NAME' is defined, or else a data
- section directive followed by a synthetic label.
-
-\1f
-File: gccint.info, Node: Alignment Output, Prev: Exception Region Output, Up: Assembler Format
-
-Assembler Commands for Alignment
---------------------------------
-
- This describes commands for alignment.
-
-`JUMP_ALIGN (LABEL)'
- The alignment (log base 2) to put in front of LABEL, which is a
- common destination of jumps and has no fallthru incoming edge.
-
- This macro need not be defined if you don't want any special
- alignment to be done at such a time. Most machine descriptions do
- not currently define the macro.
-
- Unless it's necessary to inspect the LABEL parameter, it is better
- to set the variable ALIGN_JUMPS in the target's
- `OVERRIDE_OPTIONS'. Otherwise, you should try to honor the user's
- selection in ALIGN_JUMPS in a `JUMP_ALIGN' implementation.
-
-`LABEL_ALIGN_AFTER_BARRIER (LABEL)'
- The alignment (log base 2) to put in front of LABEL, which follows
- a `BARRIER'.
-
- This macro need not be defined if you don't want any special
- alignment to be done at such a time. Most machine descriptions do
- not currently define the macro.
-
-`LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP'
- The maximum number of bytes to skip when applying
- `LABEL_ALIGN_AFTER_BARRIER'. This works only if
- `ASM_OUTPUT_MAX_SKIP_ALIGN' is defined.
-
-`LOOP_ALIGN (LABEL)'
- The alignment (log base 2) to put in front of LABEL, which follows
- a `NOTE_INSN_LOOP_BEG' note.
-
- This macro need not be defined if you don't want any special
- alignment to be done at such a time. Most machine descriptions do
- not currently define the macro.
-
- Unless it's necessary to inspect the LABEL parameter, it is better
- to set the variable `align_loops' in the target's
- `OVERRIDE_OPTIONS'. Otherwise, you should try to honor the user's
- selection in `align_loops' in a `LOOP_ALIGN' implementation.
-
-`LOOP_ALIGN_MAX_SKIP'
- The maximum number of bytes to skip when applying `LOOP_ALIGN'.
- This works only if `ASM_OUTPUT_MAX_SKIP_ALIGN' is defined.
-
-`LABEL_ALIGN (LABEL)'
- The alignment (log base 2) to put in front of LABEL. If
- `LABEL_ALIGN_AFTER_BARRIER' / `LOOP_ALIGN' specify a different
- alignment, the maximum of the specified values is used.
-
- Unless it's necessary to inspect the LABEL parameter, it is better
- to set the variable `align_labels' in the target's
- `OVERRIDE_OPTIONS'. Otherwise, you should try to honor the user's
- selection in `align_labels' in a `LABEL_ALIGN' implementation.
-
-`LABEL_ALIGN_MAX_SKIP'
- The maximum number of bytes to skip when applying `LABEL_ALIGN'.
- This works only if `ASM_OUTPUT_MAX_SKIP_ALIGN' is defined.
-
-`ASM_OUTPUT_SKIP (STREAM, NBYTES)'
- A C statement to output to the stdio stream STREAM an assembler
- instruction to advance the location counter by NBYTES bytes.
- Those bytes should be zero when loaded. NBYTES will be a C
- expression of type `int'.
-
-`ASM_NO_SKIP_IN_TEXT'
- Define this macro if `ASM_OUTPUT_SKIP' should not be used in the
- text section because it fails to put zeros in the bytes that are
- skipped. This is true on many Unix systems, where the pseudo-op
- to skip bytes produces no-op instructions rather than zeros when
- used in the text section.
-
-`ASM_OUTPUT_ALIGN (STREAM, POWER)'
- A C statement to output to the stdio stream STREAM an assembler
- command to advance the location counter to a multiple of 2 to the
- POWER bytes. POWER will be a C expression of type `int'.
-
-`ASM_OUTPUT_MAX_SKIP_ALIGN (STREAM, POWER, MAX_SKIP)'
- A C statement to output to the stdio stream STREAM an assembler
- command to advance the location counter to a multiple of 2 to the
- POWER bytes, but only if MAX_SKIP or fewer bytes are needed to
- satisfy the alignment request. POWER and MAX_SKIP will be a C
- expression of type `int'.
-
-\1f
-File: gccint.info, Node: Debugging Info, Next: Cross-compilation, Prev: Assembler Format, Up: Target Macros
-
-Controlling Debugging Information Format
-========================================
-
- This describes how to specify debugging information.
-
-* Menu:
-
-* All Debuggers:: Macros that affect all debugging formats uniformly.
-* DBX Options:: Macros enabling specific options in DBX format.
-* DBX Hooks:: Hook macros for varying DBX format.
-* File Names and DBX:: Macros controlling output of file names in DBX format.
-* SDB and DWARF:: Macros for SDB (COFF) and DWARF formats.
-* VMS Debug:: Macros for VMS debug format.
-
-\1f
-File: gccint.info, Node: All Debuggers, Next: DBX Options, Up: Debugging Info
-
-Macros Affecting All Debugging Formats
---------------------------------------
-
- These macros affect all debugging formats.
-
-`DBX_REGISTER_NUMBER (REGNO)'
- A C expression that returns the DBX register number for the
- compiler register number REGNO. In the default macro provided,
- the value of this expression will be REGNO itself. But sometimes
- there are some registers that the compiler knows about and DBX
- does not, or vice versa. In such cases, some register may need to
- have one number in the compiler and another for DBX.
-
- If two registers have consecutive numbers inside GCC, and they can
- be used as a pair to hold a multiword value, then they _must_ have
- consecutive numbers after renumbering with `DBX_REGISTER_NUMBER'.
- Otherwise, debuggers will be unable to access such a pair, because
- they expect register pairs to be consecutive in their own
- numbering scheme.
-
- If you find yourself defining `DBX_REGISTER_NUMBER' in way that
- does not preserve register pairs, then what you must do instead is
- redefine the actual register numbering scheme.
-
-`DEBUGGER_AUTO_OFFSET (X)'
- A C expression that returns the integer offset value for an
- automatic variable having address X (an RTL expression). The
- default computation assumes that X is based on the frame-pointer
- and gives the offset from the frame-pointer. This is required for
- targets that produce debugging output for DBX or COFF-style
- debugging output for SDB and allow the frame-pointer to be
- eliminated when the `-g' options is used.
-
-`DEBUGGER_ARG_OFFSET (OFFSET, X)'
- A C expression that returns the integer offset value for an
- argument having address X (an RTL expression). The nominal offset
- is OFFSET.
-
-`PREFERRED_DEBUGGING_TYPE'
- A C expression that returns the type of debugging output GCC should
- produce when the user specifies just `-g'. Define this if you
- have arranged for GCC to support more than one format of debugging
- output. Currently, the allowable values are `DBX_DEBUG',
- `SDB_DEBUG', `DWARF_DEBUG', `DWARF2_DEBUG', `XCOFF_DEBUG',
- `VMS_DEBUG', and `VMS_AND_DWARF2_DEBUG'.
-
- When the user specifies `-ggdb', GCC normally also uses the value
- of this macro to select the debugging output format, but with two
- exceptions. If `DWARF2_DEBUGGING_INFO' is defined and
- `LINKER_DOES_NOT_WORK_WITH_DWARF2' is not defined, GCC uses the
- value `DWARF2_DEBUG'. Otherwise, if `DBX_DEBUGGING_INFO' is
- defined, GCC uses `DBX_DEBUG'.
-
- The value of this macro only affects the default debugging output;
- the user can always get a specific type of output by using
- `-gstabs', `-gcoff', `-gdwarf-1', `-gdwarf-2', `-gxcoff', or
- `-gvms'.
-
-\1f
-File: gccint.info, Node: DBX Options, Next: DBX Hooks, Prev: All Debuggers, Up: Debugging Info
-
-Specific Options for DBX Output
--------------------------------
-
- These are specific options for DBX output.
-
-`DBX_DEBUGGING_INFO'
- Define this macro if GCC should produce debugging output for DBX
- in response to the `-g' option.
-
-`XCOFF_DEBUGGING_INFO'
- Define this macro if GCC should produce XCOFF format debugging
- output in response to the `-g' option. This is a variant of DBX
- format.
-
-`DEFAULT_GDB_EXTENSIONS'
- Define this macro to control whether GCC should by default generate
- GDB's extended version of DBX debugging information (assuming
- DBX-format debugging information is enabled at all). If you don't
- define the macro, the default is 1: always generate the extended
- information if there is any occasion to.
-
-`DEBUG_SYMS_TEXT'
- Define this macro if all `.stabs' commands should be output while
- in the text section.
-
-`ASM_STABS_OP'
- A C string constant, including spacing, naming the assembler
- pseudo op to use instead of `"\t.stabs\t"' to define an ordinary
- debugging symbol. If you don't define this macro, `"\t.stabs\t"'
- is used. This macro applies only to DBX debugging information
- format.
-
-`ASM_STABD_OP'
- A C string constant, including spacing, naming the assembler
- pseudo op to use instead of `"\t.stabd\t"' to define a debugging
- symbol whose value is the current location. If you don't define
- this macro, `"\t.stabd\t"' is used. This macro applies only to
- DBX debugging information format.
-
-`ASM_STABN_OP'
- A C string constant, including spacing, naming the assembler
- pseudo op to use instead of `"\t.stabn\t"' to define a debugging
- symbol with no name. If you don't define this macro,
- `"\t.stabn\t"' is used. This macro applies only to DBX debugging
- information format.
-
-`DBX_NO_XREFS'
- Define this macro if DBX on your system does not support the
- construct `xsTAGNAME'. On some systems, this construct is used to
- describe a forward reference to a structure named TAGNAME. On
- other systems, this construct is not supported at all.
-
-`DBX_CONTIN_LENGTH'
- A symbol name in DBX-format debugging information is normally
- continued (split into two separate `.stabs' directives) when it
- exceeds a certain length (by default, 80 characters). On some
- operating systems, DBX requires this splitting; on others,
- splitting must not be done. You can inhibit splitting by defining
- this macro with the value zero. You can override the default
- splitting-length by defining this macro as an expression for the
- length you desire.
-
-`DBX_CONTIN_CHAR'
- Normally continuation is indicated by adding a `\' character to
- the end of a `.stabs' string when a continuation follows. To use
- a different character instead, define this macro as a character
- constant for the character you want to use. Do not define this
- macro if backslash is correct for your system.
-
-`DBX_STATIC_STAB_DATA_SECTION'
- Define this macro if it is necessary to go to the data section
- before outputting the `.stabs' pseudo-op for a non-global static
- variable.
-
-`DBX_TYPE_DECL_STABS_CODE'
- The value to use in the "code" field of the `.stabs' directive for
- a typedef. The default is `N_LSYM'.
-
-`DBX_STATIC_CONST_VAR_CODE'
- The value to use in the "code" field of the `.stabs' directive for
- a static variable located in the text section. DBX format does not
- provide any "right" way to do this. The default is `N_FUN'.
-
-`DBX_REGPARM_STABS_CODE'
- The value to use in the "code" field of the `.stabs' directive for
- a parameter passed in registers. DBX format does not provide any
- "right" way to do this. The default is `N_RSYM'.
-
-`DBX_REGPARM_STABS_LETTER'
- The letter to use in DBX symbol data to identify a symbol as a
- parameter passed in registers. DBX format does not customarily
- provide any way to do this. The default is `'P''.
-
-`DBX_MEMPARM_STABS_LETTER'
- The letter to use in DBX symbol data to identify a symbol as a
- stack parameter. The default is `'p''.
-
-`DBX_FUNCTION_FIRST'
- Define this macro if the DBX information for a function and its
- arguments should precede the assembler code for the function.
- Normally, in DBX format, the debugging information entirely
- follows the assembler code.
-
-`DBX_LBRAC_FIRST'
- Define this macro if the `N_LBRAC' symbol for a block should
- precede the debugging information for variables and functions
- defined in that block. Normally, in DBX format, the `N_LBRAC'
- symbol comes first.
-
-`DBX_BLOCKS_FUNCTION_RELATIVE'
- Define this macro if the value of a symbol describing the scope of
- a block (`N_LBRAC' or `N_RBRAC') should be relative to the start
- of the enclosing function. Normally, GCC uses an absolute address.
-
-`DBX_USE_BINCL'
- Define this macro if GCC should generate `N_BINCL' and `N_EINCL'
- stabs for included header files, as on Sun systems. This macro
- also directs GCC to output a type number as a pair of a file
- number and a type number within the file. Normally, GCC does not
- generate `N_BINCL' or `N_EINCL' stabs, and it outputs a single
- number for a type number.
-
-\1f
-File: gccint.info, Node: DBX Hooks, Next: File Names and DBX, Prev: DBX Options, Up: Debugging Info
-
-Open-Ended Hooks for DBX Format
--------------------------------
-
- These are hooks for DBX format.
-
-`DBX_OUTPUT_LBRAC (STREAM, NAME)'
- Define this macro to say how to output to STREAM the debugging
- information for the start of a scope level for variable names. The
- argument NAME is the name of an assembler symbol (for use with
- `assemble_name') whose value is the address where the scope begins.
-
-`DBX_OUTPUT_RBRAC (STREAM, NAME)'
- Like `DBX_OUTPUT_LBRAC', but for the end of a scope level.
-
-`DBX_OUTPUT_NFUN (STREAM, LSCOPE_LABEL, DECL)'
- Define this macro if the target machine requires special handling
- to output an `N_FUN' entry for the function DECL.
-
-`DBX_OUTPUT_ENUM (STREAM, TYPE)'
- Define this macro if the target machine requires special handling
- to output an enumeration type. The definition should be a C
- statement (sans semicolon) to output the appropriate information
- to STREAM for the type TYPE.
-
-`DBX_OUTPUT_FUNCTION_END (STREAM, FUNCTION)'
- Define this macro if the target machine requires special output at
- the end of the debugging information for a function. The
- definition should be a C statement (sans semicolon) to output the
- appropriate information to STREAM. FUNCTION is the
- `FUNCTION_DECL' node for the function.
-
-`DBX_OUTPUT_STANDARD_TYPES (SYMS)'
- Define this macro if you need to control the order of output of the
- standard data types at the beginning of compilation. The argument
- SYMS is a `tree' which is a chain of all the predefined global
- symbols, including names of data types.
-
- Normally, DBX output starts with definitions of the types for
- integers and characters, followed by all the other predefined
- types of the particular language in no particular order.
-
- On some machines, it is necessary to output different particular
- types first. To do this, define `DBX_OUTPUT_STANDARD_TYPES' to
- output those symbols in the necessary order. Any predefined types
- that you don't explicitly output will be output afterward in no
- particular order.
-
- Be careful not to define this macro so that it works only for C.
- There are no global variables to access most of the built-in
- types, because another language may have another set of types.
- The way to output a particular type is to look through SYMS to see
- if you can find it. Here is an example:
-
- {
- tree decl;
- for (decl = syms; decl; decl = TREE_CHAIN (decl))
- if (!strcmp (IDENTIFIER_POINTER (DECL_NAME (decl)),
- "long int"))
- dbxout_symbol (decl);
- ...
- }
-
- This does nothing if the expected type does not exist.
-
- See the function `init_decl_processing' in `c-decl.c' to find the
- names to use for all the built-in C types.
-
- Here is another way of finding a particular type:
-
- {
- tree decl;
- for (decl = syms; decl; decl = TREE_CHAIN (decl))
- if (TREE_CODE (decl) == TYPE_DECL
- && (TREE_CODE (TREE_TYPE (decl))
- == INTEGER_CST)
- && TYPE_PRECISION (TREE_TYPE (decl)) == 16
- && TYPE_UNSIGNED (TREE_TYPE (decl)))
- /* This must be `unsigned short'. */
- dbxout_symbol (decl);
- ...
- }
-
-`NO_DBX_FUNCTION_END'
- Some stabs encapsulation formats (in particular ECOFF), cannot
- handle the `.stabs "",N_FUN,,0,0,Lscope-function-1' gdb dbx
- extension construct. On those machines, define this macro to turn
- this feature off without disturbing the rest of the gdb extensions.
-
-
-\1f
-File: gccint.info, Node: File Names and DBX, Next: SDB and DWARF, Prev: DBX Hooks, Up: Debugging Info
-
-File Names in DBX Format
-------------------------
-
- This describes file names in DBX format.
-
-`DBX_WORKING_DIRECTORY'
- Define this if DBX wants to have the current directory recorded in
- each object file.
-
- Note that the working directory is always recorded if GDB
- extensions are enabled.
-
-`DBX_OUTPUT_MAIN_SOURCE_FILENAME (STREAM, NAME)'
- A C statement to output DBX debugging information to the stdio
- stream STREAM which indicates that file NAME is the main source
- file--the file specified as the input file for compilation. This
- macro is called only once, at the beginning of compilation.
-
- This macro need not be defined if the standard form of output for
- DBX debugging information is appropriate.
-
-`DBX_OUTPUT_MAIN_SOURCE_DIRECTORY (STREAM, NAME)'
- A C statement to output DBX debugging information to the stdio
- stream STREAM which indicates that the current directory during
- compilation is named NAME.
-
- This macro need not be defined if the standard form of output for
- DBX debugging information is appropriate.
-
-`DBX_OUTPUT_MAIN_SOURCE_FILE_END (STREAM, NAME)'
- A C statement to output DBX debugging information at the end of
- compilation of the main source file NAME.
-
- If you don't define this macro, nothing special is output at the
- end of compilation, which is correct for most machines.
-
-`DBX_OUTPUT_SOURCE_FILENAME (STREAM, NAME)'
- A C statement to output DBX debugging information to the stdio
- stream STREAM which indicates that file NAME is the current source
- file. This output is generated each time input shifts to a
- different source file as a result of `#include', the end of an
- included file, or a `#line' command.
-
- This macro need not be defined if the standard form of output for
- DBX debugging information is appropriate.
-
-\1f
-File: gccint.info, Node: SDB and DWARF, Next: VMS Debug, Prev: File Names and DBX, Up: Debugging Info
-
-Macros for SDB and DWARF Output
--------------------------------
-
- Here are macros for SDB and DWARF output.
-
-`SDB_DEBUGGING_INFO'
- Define this macro if GCC should produce COFF-style debugging output
- for SDB in response to the `-g' option.
-
-`DWARF_DEBUGGING_INFO'
- Define this macro if GCC should produce dwarf format debugging
- output in response to the `-g' option.
-
-`DWARF2_DEBUGGING_INFO'
- Define this macro if GCC should produce dwarf version 2 format
- debugging output in response to the `-g' option.
-
- To support optional call frame debugging information, you must also
- define `INCOMING_RETURN_ADDR_RTX' and either set
- `RTX_FRAME_RELATED_P' on the prologue insns if you use RTL for the
- prologue, or call `dwarf2out_def_cfa' and `dwarf2out_reg_save' as
- appropriate from `TARGET_ASM_FUNCTION_PROLOGUE' if you don't.
-
-`DWARF2_FRAME_INFO'
- Define this macro to a nonzero value if GCC should always output
- Dwarf 2 frame information. If `DWARF2_UNWIND_INFO' (*note
- Exception Region Output:: is nonzero, GCC will output this
- information not matter how you define `DWARF2_FRAME_INFO'.
-
-`LINKER_DOES_NOT_WORK_WITH_DWARF2'
- Define this macro if the linker does not work with Dwarf version 2.
- Normally, if the user specifies only `-ggdb' GCC will use Dwarf
- version 2 if available; this macro disables this. See the
- description of the `PREFERRED_DEBUGGING_TYPE' macro for more
- details.
-
-`DWARF2_GENERATE_TEXT_SECTION_LABEL'
- By default, the Dwarf 2 debugging information generator will
- generate a label to mark the beginning of the text section. If it
- is better simply to use the name of the text section itself,
- rather than an explicit label, to indicate the beginning of the
- text section, define this macro to zero.
-
-`DWARF2_ASM_LINE_DEBUG_INFO'
- Define this macro to be a nonzero value if the assembler can
- generate Dwarf 2 line debug info sections. This will result in
- much more compact line number tables, and hence is desirable if it
- works.
-
-`PUT_SDB_...'
- Define these macros to override the assembler syntax for the
- special SDB assembler directives. See `sdbout.c' for a list of
- these macros and their arguments. If the standard syntax is used,
- you need not define them yourself.
-
-`SDB_DELIM'
- Some assemblers do not support a semicolon as a delimiter, even
- between SDB assembler directives. In that case, define this macro
- to be the delimiter to use (usually `\n'). It is not necessary to
- define a new set of `PUT_SDB_OP' macros if this is the only change
- required.
-
-`SDB_GENERATE_FAKE'
- Define this macro to override the usual method of constructing a
- dummy name for anonymous structure and union types. See
- `sdbout.c' for more information.
-
-`SDB_ALLOW_UNKNOWN_REFERENCES'
- Define this macro to allow references to unknown structure, union,
- or enumeration tags to be emitted. Standard COFF does not allow
- handling of unknown references, MIPS ECOFF has support for it.
-
-`SDB_ALLOW_FORWARD_REFERENCES'
- Define this macro to allow references to structure, union, or
- enumeration tags that have not yet been seen to be handled. Some
- assemblers choke if forward tags are used, while some require it.
-
-\1f
-File: gccint.info, Node: VMS Debug, Prev: SDB and DWARF, Up: Debugging Info
-
-Macros for VMS Debug Format
----------------------------
-
- Here are macros for VMS debug format.
-
-`VMS_DEBUGGING_INFO'
- Define this macro if GCC should produce debugging output for VMS
- in response to the `-g' option. The default behavior for VMS is
- to generate minimal debug info for a traceback in the absence of
- `-g' unless explicitly overridden with `-g0'. This behavior is
- controlled by `OPTIMIZATION_OPTIONS' and `OVERRIDE_OPTIONS'.
-
-\1f
-File: gccint.info, Node: Cross-compilation, Next: Mode Switching, Prev: Debugging Info, Up: Target Macros
-
-Cross Compilation and Floating Point
-====================================
-
- While all modern machines use 2's complement representation for
-integers, there are a variety of representations for floating point
-numbers. This means that in a cross-compiler the representation of
-floating point numbers in the compiled program may be different from
-that used in the machine doing the compilation.
-
- Because different representation systems may offer different amounts
-of range and precision, the cross compiler cannot safely use the host
-machine's floating point arithmetic. Therefore, floating point
-constants must be represented in the target machine's format. This
-means that the cross compiler cannot use `atof' to parse a floating
-point constant; it must have its own special routine to use instead.
-Also, constant folding must emulate the target machine's arithmetic (or
-must not be done at all).
-
- The macros in the following table should be defined only if you are
-cross compiling between different floating point formats.
-
- Otherwise, don't define them. Then default definitions will be set
-up which use `double' as the data type, `==' to test for equality, etc.
-
- You don't need to worry about how many times you use an operand of
-any of these macros. The compiler never uses operands which have side
-effects.
-
-`REAL_VALUE_TYPE'
- A macro for the C data type to be used to hold a floating point
- value in the target machine's format. Typically this would be a
- `struct' containing an array of `int'.
-
-`REAL_VALUES_EQUAL (X, Y)'
- A macro for a C expression which compares for equality the two
- values, X and Y, both of type `REAL_VALUE_TYPE'.
-
-`REAL_VALUES_LESS (X, Y)'
- A macro for a C expression which tests whether X is less than Y,
- both values being of type `REAL_VALUE_TYPE' and interpreted as
- floating point numbers in the target machine's representation.
-
-`REAL_VALUE_LDEXP (X, SCALE)'
- A macro for a C expression which performs the standard library
- function `ldexp', but using the target machine's floating point
- representation. Both X and the value of the expression have type
- `REAL_VALUE_TYPE'. The second argument, SCALE, is an integer.
-
-`REAL_VALUE_FIX (X)'
- A macro whose definition is a C expression to convert the
- target-machine floating point value X to a signed integer. X has
- type `REAL_VALUE_TYPE'.
-
-`REAL_VALUE_UNSIGNED_FIX (X)'
- A macro whose definition is a C expression to convert the
- target-machine floating point value X to an unsigned integer. X
- has type `REAL_VALUE_TYPE'.
-
-`REAL_VALUE_RNDZINT (X)'
- A macro whose definition is a C expression to round the
- target-machine floating point value X towards zero to an integer
- value (but still as a floating point number). X has type
- `REAL_VALUE_TYPE', and so does the value.
-
-`REAL_VALUE_UNSIGNED_RNDZINT (X)'
- A macro whose definition is a C expression to round the
- target-machine floating point value X towards zero to an unsigned
- integer value (but still represented as a floating point number).
- X has type `REAL_VALUE_TYPE', and so does the value.
-
-`REAL_VALUE_ATOF (STRING, MODE)'
- A macro for a C expression which converts STRING, an expression of
- type `char *', into a floating point number in the target machine's
- representation for mode MODE. The value has type
- `REAL_VALUE_TYPE'.
-
-`REAL_INFINITY'
- Define this macro if infinity is a possible floating point value,
- and therefore division by 0 is legitimate.
-
-`REAL_VALUE_ISINF (X)'
- A macro for a C expression which determines whether X, a floating
- point value, is infinity. The value has type `int'. By default,
- this is defined to call `isinf'.
-
-`REAL_VALUE_ISNAN (X)'
- A macro for a C expression which determines whether X, a floating
- point value, is a "nan" (not-a-number). The value has type `int'.
- By default, this is defined to call `isnan'.
-
- Define the following additional macros if you want to make floating
-point constant folding work while cross compiling. If you don't define
-them, cross compilation is still possible, but constant folding will
-not happen for floating point values.
-
-`REAL_ARITHMETIC (OUTPUT, CODE, X, Y)'
- A macro for a C statement which calculates an arithmetic operation
- of the two floating point values X and Y, both of type
- `REAL_VALUE_TYPE' in the target machine's representation, to
- produce a result of the same type and representation which is
- stored in OUTPUT (which will be a variable).
-
- The operation to be performed is specified by CODE, a tree code
- which will always be one of the following: `PLUS_EXPR',
- `MINUS_EXPR', `MULT_EXPR', `RDIV_EXPR', `MAX_EXPR', `MIN_EXPR'.
-
- The expansion of this macro is responsible for checking for
- overflow. If overflow happens, the macro expansion should execute
- the statement `return 0;', which indicates the inability to
- perform the arithmetic operation requested.
-
-`REAL_VALUE_NEGATE (X)'
- A macro for a C expression which returns the negative of the
- floating point value X. Both X and the value of the expression
- have type `REAL_VALUE_TYPE' and are in the target machine's
- floating point representation.
-
- There is no way for this macro to report overflow, since overflow
- can't happen in the negation operation.
-
-`REAL_VALUE_TRUNCATE (MODE, X)'
- A macro for a C expression which converts the floating point value
- X to mode MODE.
-
- Both X and the value of the expression are in the target machine's
- floating point representation and have type `REAL_VALUE_TYPE'.
- However, the value should have an appropriate bit pattern to be
- output properly as a floating constant whose precision accords
- with mode MODE.
-
- There is no way for this macro to report overflow.
-
-`REAL_VALUE_TO_INT (LOW, HIGH, X)'
- A macro for a C expression which converts a floating point value X
- into a double-precision integer which is then stored into LOW and
- HIGH, two variables of type INT.
-
-`REAL_VALUE_FROM_INT (X, LOW, HIGH, MODE)'
- A macro for a C expression which converts a double-precision
- integer found in LOW and HIGH, two variables of type INT, into a
- floating point value which is then stored into X. The value is in
- the target machine's representation for mode MODE and has the type
- `REAL_VALUE_TYPE'.
-
-\1f
-File: gccint.info, Node: Mode Switching, Next: Target Attributes, Prev: Cross-compilation, Up: Target Macros
-
-Mode Switching Instructions
-===========================
-
- The following macros control mode switching optimizations:
-
-`OPTIMIZE_MODE_SWITCHING (ENTITY)'
- Define this macro if the port needs extra instructions inserted
- for mode switching in an optimizing compilation.
-
- For an example, the SH4 can perform both single and double
- precision floating point operations, but to perform a single
- precision operation, the FPSCR PR bit has to be cleared, while for
- a double precision operation, this bit has to be set. Changing
- the PR bit requires a general purpose register as a scratch
- register, hence these FPSCR sets have to be inserted before
- reload, i.e. you can't put this into instruction emitting or
- `MACHINE_DEPENDENT_REORG'.
-
- You can have multiple entities that are mode-switched, and select
- at run time which entities actually need it.
- `OPTIMIZE_MODE_SWITCHING' should return nonzero for any ENTITY
- that needs mode-switching. If you define this macro, you also
- have to define `NUM_MODES_FOR_MODE_SWITCHING', `MODE_NEEDED',
- `MODE_PRIORITY_TO_MODE' and `EMIT_MODE_SET'. `NORMAL_MODE' is
- optional.
-
-`NUM_MODES_FOR_MODE_SWITCHING'
- If you define `OPTIMIZE_MODE_SWITCHING', you have to define this as
- initializer for an array of integers. Each initializer element N
- refers to an entity that needs mode switching, and specifies the
- number of different modes that might need to be set for this
- entity. The position of the initializer in the initializer -
- starting counting at zero - determines the integer that is used to
- refer to the mode-switched entity in question. In macros that
- take mode arguments / yield a mode result, modes are represented
- as numbers 0 ... N - 1. N is used to specify that no mode switch
- is needed / supplied.
-
-`MODE_NEEDED (ENTITY, INSN)'
- ENTITY is an integer specifying a mode-switched entity. If
- `OPTIMIZE_MODE_SWITCHING' is defined, you must define this macro to
- return an integer value not larger than the corresponding element
- in `NUM_MODES_FOR_MODE_SWITCHING', to denote the mode that ENTITY
- must be switched into prior to the execution of INSN.
-
-`NORMAL_MODE (ENTITY)'
- If this macro is defined, it is evaluated for every ENTITY that
- needs mode switching. It should evaluate to an integer, which is
- a mode that ENTITY is assumed to be switched to at function entry
- and exit.
-
-`MODE_PRIORITY_TO_MODE (ENTITY, N)'
- This macro specifies the order in which modes for ENTITY are
- processed. 0 is the highest priority,
- `NUM_MODES_FOR_MODE_SWITCHING[ENTITY] - 1' the lowest. The value
- of the macro should be an integer designating a mode for ENTITY.
- For any fixed ENTITY, `mode_priority_to_mode' (ENTITY, N) shall be
- a bijection in 0 ... `num_modes_for_mode_switching[ENTITY] - 1'.
-
-`EMIT_MODE_SET (ENTITY, MODE, HARD_REGS_LIVE)'
- Generate one or more insns to set ENTITY to MODE. HARD_REG_LIVE
- is the set of hard registers live at the point where the insn(s)
- are to be inserted.
-
-This is doc/gccint.info, produced by makeinfo version 4.5 from
+This is doc/gccint.info, produced by makeinfo version 4.11 from
doc/gccint.texi.
INFO-DIR-SECTION Programming
funds for GNU development.
\1f
-File: gccint.info, Node: Back End, Prev: Front End, Up: gcc Directory
+File: gccint.info, Node: Patterns, Next: Example, Prev: Overview, Up: Machine Desc
+
+9.2 Everything about Instruction Patterns
+=========================================
+
+Each instruction pattern contains an incomplete RTL expression, with
+pieces to be filled in later, operand constraints that restrict how the
+pieces can be filled in, and an output pattern or C code to generate
+the assembler output, all wrapped up in a `define_insn' expression.
+
+ A `define_insn' is an RTL expression containing four or five
+operands:
+
+ 1. An optional name. The presence of a name indicate that this
+ instruction pattern can perform a certain standard job for the
+ RTL-generation pass of the compiler. This pass knows certain
+ names and will use the instruction patterns with those names, if
+ the names are defined in the machine description.
+
+ The absence of a name is indicated by writing an empty string
+ where the name should go. Nameless instruction patterns are never
+ used for generating RTL code, but they may permit several simpler
+ insns to be combined later on.
+
+ Names that are not thus known and used in RTL-generation have no
+ effect; they are equivalent to no name at all.
+
+ For the purpose of debugging the compiler, you may also specify a
+ name beginning with the `*' character. Such a name is used only
+ for identifying the instruction in RTL dumps; it is entirely
+ equivalent to having a nameless pattern for all other purposes.
+
+ 2. The "RTL template" (*note RTL Template::) is a vector of incomplete
+ RTL expressions which show what the instruction should look like.
+ It is incomplete because it may contain `match_operand',
+ `match_operator', and `match_dup' expressions that stand for
+ operands of the instruction.
+
+ If the vector has only one element, that element is the template
+ for the instruction pattern. If the vector has multiple elements,
+ then the instruction pattern is a `parallel' expression containing
+ the elements described.
+
+ 3. A condition. This is a string which contains a C expression that
+ is the final test to decide whether an insn body matches this
+ pattern.
+
+ For a named pattern, the condition (if present) may not depend on
+ the data in the insn being matched, but only the
+ target-machine-type flags. The compiler needs to test these
+ conditions during initialization in order to learn exactly which
+ named instructions are available in a particular run.
+
+ For nameless patterns, the condition is applied only when matching
+ an individual insn, and only after the insn has matched the
+ pattern's recognition template. The insn's operands may be found
+ in the vector `operands'. For an insn where the condition has
+ once matched, it can't be used to control register allocation, for
+ example by excluding certain hard registers or hard register
+ combinations.
+
+ 4. The "output template": a string that says how to output matching
+ insns as assembler code. `%' in this string specifies where to
+ substitute the value of an operand. *Note Output Template::.
+
+ When simple substitution isn't general enough, you can specify a
+ piece of C code to compute the output. *Note Output Statement::.
+
+ 5. Optionally, a vector containing the values of attributes for insns
+ matching this pattern. *Note Insn Attributes::.
-Anatomy of a Target Back End
-----------------------------
+\1f
+File: gccint.info, Node: Example, Next: RTL Template, Prev: Patterns, Up: Machine Desc
+
+9.3 Example of `define_insn'
+============================
+
+Here is an actual example of an instruction pattern, for the
+68000/68020.
+
+ (define_insn "tstsi"
+ [(set (cc0)
+ (match_operand:SI 0 "general_operand" "rm"))]
+ ""
+ "*
+ {
+ if (TARGET_68020 || ! ADDRESS_REG_P (operands[0]))
+ return \"tstl %0\";
+ return \"cmpl #0,%0\";
+ }")
+
+This can also be written using braced strings:
+
+ (define_insn "tstsi"
+ [(set (cc0)
+ (match_operand:SI 0 "general_operand" "rm"))]
+ ""
+ {
+ if (TARGET_68020 || ! ADDRESS_REG_P (operands[0]))
+ return "tstl %0";
+ return "cmpl #0,%0";
+ })
+
+ This is an instruction that sets the condition codes based on the
+value of a general operand. It has no condition, so any insn whose RTL
+description has the form shown may be handled according to this
+pattern. The name `tstsi' means "test a `SImode' value" and tells the
+RTL generation pass that, when it is necessary to test such a value, an
+insn to do so can be constructed using this pattern.
+
+ The output control string is a piece of C code which chooses which
+output template to return based on the kind of operand and the specific
+type of CPU for which code is being generated.
+
+ `"rm"' is an operand constraint. Its meaning is explained below.
+
+\1f
+File: gccint.info, Node: RTL Template, Next: Output Template, Prev: Example, Up: Machine Desc
+
+9.4 RTL Template
+================
+
+The RTL template is used to define which insns match the particular
+pattern and how to find their operands. For named patterns, the RTL
+template also says how to construct an insn from specified operands.
+
+ Construction involves substituting specified operands into a copy of
+the template. Matching involves determining the values that serve as
+the operands in the insn being matched. Both of these activities are
+controlled by special expression types that direct matching and
+substitution of the operands.
+
+`(match_operand:M N PREDICATE CONSTRAINT)'
+ This expression is a placeholder for operand number N of the insn.
+ When constructing an insn, operand number N will be substituted at
+ this point. When matching an insn, whatever appears at this
+ position in the insn will be taken as operand number N; but it
+ must satisfy PREDICATE or this instruction pattern will not match
+ at all.
+
+ Operand numbers must be chosen consecutively counting from zero in
+ each instruction pattern. There may be only one `match_operand'
+ expression in the pattern for each operand number. Usually
+ operands are numbered in the order of appearance in `match_operand'
+ expressions. In the case of a `define_expand', any operand numbers
+ used only in `match_dup' expressions have higher values than all
+ other operand numbers.
+
+ PREDICATE is a string that is the name of a C function that
+ accepts two arguments, an expression and a machine mode. During
+ matching, the function will be called with the putative operand as
+ the expression and M as the mode argument (if M is not specified,
+ `VOIDmode' will be used, which normally causes PREDICATE to accept
+ any mode). If it returns zero, this instruction pattern fails to
+ match. PREDICATE may be an empty string; then it means no test is
+ to be done on the operand, so anything which occurs in this
+ position is valid.
+
+ Most of the time, PREDICATE will reject modes other than M--but
+ not always. For example, the predicate `address_operand' uses M
+ as the mode of memory ref that the address should be valid for.
+ Many predicates accept `const_int' nodes even though their mode is
+ `VOIDmode'.
+
+ CONSTRAINT controls reloading and the choice of the best register
+ class to use for a value, as explained later (*note Constraints::).
+
+ People are often unclear on the difference between the constraint
+ and the predicate. The predicate helps decide whether a given
+ insn matches the pattern. The constraint plays no role in this
+ decision; instead, it controls various decisions in the case of an
+ insn which does match.
+
+ On CISC machines, the most common PREDICATE is
+ `"general_operand"'. This function checks that the putative
+ operand is either a constant, a register or a memory reference,
+ and that it is valid for mode M.
+
+ For an operand that must be a register, PREDICATE should be
+ `"register_operand"'. Using `"general_operand"' would be valid,
+ since the reload pass would copy any non-register operands through
+ registers, but this would make GCC do extra work, it would prevent
+ invariant operands (such as constant) from being removed from
+ loops, and it would prevent the register allocator from doing the
+ best possible job. On RISC machines, it is usually most efficient
+ to allow PREDICATE to accept only objects that the constraints
+ allow.
+
+ For an operand that must be a constant, you must be sure to either
+ use `"immediate_operand"' for PREDICATE, or make the instruction
+ pattern's extra condition require a constant, or both. You cannot
+ expect the constraints to do this work! If the constraints allow
+ only constants, but the predicate allows something else, the
+ compiler will crash when that case arises.
+
+`(match_scratch:M N CONSTRAINT)'
+ This expression is also a placeholder for operand number N and
+ indicates that operand must be a `scratch' or `reg' expression.
+
+ When matching patterns, this is equivalent to
+
+ (match_operand:M N "scratch_operand" PRED)
+
+ but, when generating RTL, it produces a (`scratch':M) expression.
+
+ If the last few expressions in a `parallel' are `clobber'
+ expressions whose operands are either a hard register or
+ `match_scratch', the combiner can add or delete them when
+ necessary. *Note Side Effects::.
+
+`(match_dup N)'
+ This expression is also a placeholder for operand number N. It is
+ used when the operand needs to appear more than once in the insn.
+
+ In construction, `match_dup' acts just like `match_operand': the
+ operand is substituted into the insn being constructed. But in
+ matching, `match_dup' behaves differently. It assumes that operand
+ number N has already been determined by a `match_operand'
+ appearing earlier in the recognition template, and it matches only
+ an identical-looking expression.
+
+ Note that `match_dup' should not be used to tell the compiler that
+ a particular register is being used for two operands (example:
+ `add' that adds one register to another; the second register is
+ both an input operand and the output operand). Use a matching
+ constraint (*note Simple Constraints::) for those. `match_dup' is
+ for the cases where one operand is used in two places in the
+ template, such as an instruction that computes both a quotient and
+ a remainder, where the opcode takes two input operands but the RTL
+ template has to refer to each of those twice; once for the
+ quotient pattern and once for the remainder pattern.
+
+`(match_operator:M N PREDICATE [OPERANDS...])'
+ This pattern is a kind of placeholder for a variable RTL expression
+ code.
+
+ When constructing an insn, it stands for an RTL expression whose
+ expression code is taken from that of operand N, and whose
+ operands are constructed from the patterns OPERANDS.
+
+ When matching an expression, it matches an expression if the
+ function PREDICATE returns nonzero on that expression _and_ the
+ patterns OPERANDS match the operands of the expression.
+
+ Suppose that the function `commutative_operator' is defined as
+ follows, to match any expression whose operator is one of the
+ commutative arithmetic operators of RTL and whose mode is MODE:
+
+ int
+ commutative_operator (x, mode)
+ rtx x;
+ enum machine_mode mode;
+ {
+ enum rtx_code code = GET_CODE (x);
+ if (GET_MODE (x) != mode)
+ return 0;
+ return (GET_RTX_CLASS (code) == 'c'
+ || code == EQ || code == NE);
+ }
+
+ Then the following pattern will match any RTL expression consisting
+ of a commutative operator applied to two general operands:
+
+ (match_operator:SI 3 "commutative_operator"
+ [(match_operand:SI 1 "general_operand" "g")
+ (match_operand:SI 2 "general_operand" "g")])
+
+ Here the vector `[OPERANDS...]' contains two patterns because the
+ expressions to be matched all contain two operands.
+
+ When this pattern does match, the two operands of the commutative
+ operator are recorded as operands 1 and 2 of the insn. (This is
+ done by the two instances of `match_operand'.) Operand 3 of the
+ insn will be the entire commutative expression: use `GET_CODE
+ (operands[3])' to see which commutative operator was used.
+
+ The machine mode M of `match_operator' works like that of
+ `match_operand': it is passed as the second argument to the
+ predicate function, and that function is solely responsible for
+ deciding whether the expression to be matched "has" that mode.
+
+ When constructing an insn, argument 3 of the gen-function will
+ specify the operation (i.e. the expression code) for the
+ expression to be made. It should be an RTL expression, whose
+ expression code is copied into a new expression whose operands are
+ arguments 1 and 2 of the gen-function. The subexpressions of
+ argument 3 are not used; only its expression code matters.
+
+ When `match_operator' is used in a pattern for matching an insn,
+ it usually best if the operand number of the `match_operator' is
+ higher than that of the actual operands of the insn. This improves
+ register allocation because the register allocator often looks at
+ operands 1 and 2 of insns to see if it can do register tying.
+
+ There is no way to specify constraints in `match_operator'. The
+ operand of the insn which corresponds to the `match_operator'
+ never has any constraints because it is never reloaded as a whole.
+ However, if parts of its OPERANDS are matched by `match_operand'
+ patterns, those parts may have constraints of their own.
+
+`(match_op_dup:M N[OPERANDS...])'
+ Like `match_dup', except that it applies to operators instead of
+ operands. When constructing an insn, operand number N will be
+ substituted at this point. But in matching, `match_op_dup' behaves
+ differently. It assumes that operand number N has already been
+ determined by a `match_operator' appearing earlier in the
+ recognition template, and it matches only an identical-looking
+ expression.
+
+`(match_parallel N PREDICATE [SUBPAT...])'
+ This pattern is a placeholder for an insn that consists of a
+ `parallel' expression with a variable number of elements. This
+ expression should only appear at the top level of an insn pattern.
+
+ When constructing an insn, operand number N will be substituted at
+ this point. When matching an insn, it matches if the body of the
+ insn is a `parallel' expression with at least as many elements as
+ the vector of SUBPAT expressions in the `match_parallel', if each
+ SUBPAT matches the corresponding element of the `parallel', _and_
+ the function PREDICATE returns nonzero on the `parallel' that is
+ the body of the insn. It is the responsibility of the predicate
+ to validate elements of the `parallel' beyond those listed in the
+ `match_parallel'.
+
+ A typical use of `match_parallel' is to match load and store
+ multiple expressions, which can contain a variable number of
+ elements in a `parallel'. For example,
+
+ (define_insn ""
+ [(match_parallel 0 "load_multiple_operation"
+ [(set (match_operand:SI 1 "gpc_reg_operand" "=r")
+ (match_operand:SI 2 "memory_operand" "m"))
+ (use (reg:SI 179))
+ (clobber (reg:SI 179))])]
+ ""
+ "loadm 0,0,%1,%2")
+
+ This example comes from `a29k.md'. The function
+ `load_multiple_operation' is defined in `a29k.c' and checks that
+ subsequent elements in the `parallel' are the same as the `set' in
+ the pattern, except that they are referencing subsequent registers
+ and memory locations.
+
+ An insn that matches this pattern might look like:
+
+ (parallel
+ [(set (reg:SI 20) (mem:SI (reg:SI 100)))
+ (use (reg:SI 179))
+ (clobber (reg:SI 179))
+ (set (reg:SI 21)
+ (mem:SI (plus:SI (reg:SI 100)
+ (const_int 4))))
+ (set (reg:SI 22)
+ (mem:SI (plus:SI (reg:SI 100)
+ (const_int 8))))])
+
+`(match_par_dup N [SUBPAT...])'
+ Like `match_op_dup', but for `match_parallel' instead of
+ `match_operator'.
+
+`(match_insn PREDICATE)'
+ Match a complete insn. Unlike the other `match_*' recognizers,
+ `match_insn' does not take an operand number.
+
+ The machine mode M of `match_insn' works like that of
+ `match_operand': it is passed as the second argument to the
+ predicate function, and that function is solely responsible for
+ deciding whether the expression to be matched "has" that mode.
+
+`(match_insn2 N PREDICATE)'
+ Match a complete insn.
+
+ The machine mode M of `match_insn2' works like that of
+ `match_operand': it is passed as the second argument to the
+ predicate function, and that function is solely responsible for
+ deciding whether the expression to be matched "has" that mode.
+
+
+\1f
+File: gccint.info, Node: Output Template, Next: Output Statement, Prev: RTL Template, Up: Machine Desc
+
+9.5 Output Templates and Operand Substitution
+=============================================
+
+The "output template" is a string which specifies how to output the
+assembler code for an instruction pattern. Most of the template is a
+fixed string which is output literally. The character `%' is used to
+specify where to substitute an operand; it can also be used to identify
+places where different variants of the assembler require different
+syntax.
+
+ In the simplest case, a `%' followed by a digit N says to output
+operand N at that point in the string.
+
+ `%' followed by a letter and a digit says to output an operand in an
+alternate fashion. Four letters have standard, built-in meanings
+described below. The machine description macro `PRINT_OPERAND' can
+define additional letters with nonstandard meanings.
+
+ `%cDIGIT' can be used to substitute an operand that is a constant
+value without the syntax that normally indicates an immediate operand.
+
+ `%nDIGIT' is like `%cDIGIT' except that the value of the constant is
+negated before printing.
+
+ `%aDIGIT' can be used to substitute an operand as if it were a
+memory reference, with the actual operand treated as the address. This
+may be useful when outputting a "load address" instruction, because
+often the assembler syntax for such an instruction requires you to
+write the operand as if it were a memory reference.
+
+ `%lDIGIT' is used to substitute a `label_ref' into a jump
+instruction.
+
+ `%=' outputs a number which is unique to each instruction in the
+entire compilation. This is useful for making local labels to be
+referred to more than once in a single template that generates multiple
+assembler instructions.
+
+ `%' followed by a punctuation character specifies a substitution that
+does not use an operand. Only one case is standard: `%%' outputs a `%'
+into the assembler code. Other nonstandard cases can be defined in the
+`PRINT_OPERAND' macro. You must also define which punctuation
+characters are valid with the `PRINT_OPERAND_PUNCT_VALID_P' macro.
+
+ The template may generate multiple assembler instructions. Write
+the text for the instructions, with `\;' between them.
+
+ When the RTL contains two operands which are required by constraint
+to match each other, the output template must refer only to the
+lower-numbered operand. Matching operands are not always identical,
+and the rest of the compiler arranges to put the proper RTL expression
+for printing into the lower-numbered operand.
+
+ One use of nonstandard letters or punctuation following `%' is to
+distinguish between different assembler languages for the same machine;
+for example, Motorola syntax versus MIT syntax for the 68000. Motorola
+syntax requires periods in most opcode names, while MIT syntax does
+not. For example, the opcode `movel' in MIT syntax is `move.l' in
+Motorola syntax. The same file of patterns is used for both kinds of
+output syntax, but the character sequence `%.' is used in each place
+where Motorola syntax wants a period. The `PRINT_OPERAND' macro for
+Motorola syntax defines the sequence to output a period; the macro for
+MIT syntax defines it to do nothing.
+
+ As a special case, a template consisting of the single character `#'
+instructs the compiler to first split the insn, and then output the
+resulting instructions separately. This helps eliminate redundancy in
+the output templates. If you have a `define_insn' that needs to emit
+multiple assembler instructions, and there is an matching `define_split'
+already defined, then you can simply use `#' as the output template
+instead of writing an output template that emits the multiple assembler
+instructions.
+
+ If the macro `ASSEMBLER_DIALECT' is defined, you can use construct
+of the form `{option0|option1|option2}' in the templates. These
+describe multiple variants of assembler language syntax. *Note
+Instruction Output::.
+
+\1f
+File: gccint.info, Node: Output Statement, Next: Constraints, Prev: Output Template, Up: Machine Desc
+
+9.6 C Statements for Assembler Output
+=====================================
+
+Often a single fixed template string cannot produce correct and
+efficient assembler code for all the cases that are recognized by a
+single instruction pattern. For example, the opcodes may depend on the
+kinds of operands; or some unfortunate combinations of operands may
+require extra machine instructions.
+
+ If the output control string starts with a `@', then it is actually
+a series of templates, each on a separate line. (Blank lines and
+leading spaces and tabs are ignored.) The templates correspond to the
+pattern's constraint alternatives (*note Multi-Alternative::). For
+example, if a target machine has a two-address add instruction `addr'
+to add into a register and another `addm' to add a register to memory,
+you might write this pattern:
+
+ (define_insn "addsi3"
+ [(set (match_operand:SI 0 "general_operand" "=r,m")
+ (plus:SI (match_operand:SI 1 "general_operand" "0,0")
+ (match_operand:SI 2 "general_operand" "g,r")))]
+ ""
+ "@
+ addr %2,%0
+ addm %2,%0")
+
+ If the output control string starts with a `*', then it is not an
+output template but rather a piece of C program that should compute a
+template. It should execute a `return' statement to return the
+template-string you want. Most such templates use C string literals,
+which require doublequote characters to delimit them. To include these
+doublequote characters in the string, prefix each one with `\'.
+
+ If the output control string is written as a brace block instead of a
+double-quoted string, it is automatically assumed to be C code. In that
+case, it is not necessary to put in a leading asterisk, or to escape the
+doublequotes surrounding C string literals.
+
+ The operands may be found in the array `operands', whose C data type
+is `rtx []'.
+
+ It is very common to select different ways of generating assembler
+code based on whether an immediate operand is within a certain range.
+Be careful when doing this, because the result of `INTVAL' is an
+integer on the host machine. If the host machine has more bits in an
+`int' than the target machine has in the mode in which the constant
+will be used, then some of the bits you get from `INTVAL' will be
+superfluous. For proper results, you must carefully disregard the
+values of those bits.
+
+ It is possible to output an assembler instruction and then go on to
+output or compute more of them, using the subroutine `output_asm_insn'.
+This receives two arguments: a template-string and a vector of
+operands. The vector may be `operands', or it may be another array of
+`rtx' that you declare locally and initialize yourself.
+
+ When an insn pattern has multiple alternatives in its constraints,
+often the appearance of the assembler code is determined mostly by
+which alternative was matched. When this is so, the C code can test
+the variable `which_alternative', which is the ordinal number of the
+alternative that was actually satisfied (0 for the first, 1 for the
+second alternative, etc.).
+
+ For example, suppose there are two opcodes for storing zero, `clrreg'
+for registers and `clrmem' for memory locations. Here is how a pattern
+could use `which_alternative' to choose between them:
+
+ (define_insn ""
+ [(set (match_operand:SI 0 "general_operand" "=r,m")
+ (const_int 0))]
+ ""
+ {
+ return (which_alternative == 0
+ ? "clrreg %0" : "clrmem %0");
+ })
+
+ The example above, where the assembler code to generate was _solely_
+determined by the alternative, could also have been specified as
+follows, having the output control string start with a `@':
+
+ (define_insn ""
+ [(set (match_operand:SI 0 "general_operand" "=r,m")
+ (const_int 0))]
+ ""
+ "@
+ clrreg %0
+ clrmem %0")
+
+\1f
+File: gccint.info, Node: Constraints, Next: Standard Names, Prev: Output Statement, Up: Machine Desc
+
+9.7 Operand Constraints
+=======================
+
+Each `match_operand' in an instruction pattern can specify a constraint
+for the type of operands allowed. Constraints can say whether an
+operand may be in a register, and which kinds of register; whether the
+operand can be a memory reference, and which kinds of address; whether
+the operand may be an immediate constant, and which possible values it
+may have. Constraints can also require two operands to match.
+
+* Menu:
+
+* Simple Constraints:: Basic use of constraints.
+* Multi-Alternative:: When an insn has two alternative constraint-patterns.
+* Class Preferences:: Constraints guide which hard register to put things in.
+* Modifiers:: More precise control over effects of constraints.
+* Machine Constraints:: Existing constraints for some particular machines.
+
+\1f
+File: gccint.info, Node: Simple Constraints, Next: Multi-Alternative, Up: Constraints
+
+9.7.1 Simple Constraints
+------------------------
+
+The simplest kind of constraint is a string full of letters, each of
+which describes one kind of operand that is permitted. Here are the
+letters that are allowed:
+
+whitespace
+ Whitespace characters are ignored and can be inserted at any
+ position except the first. This enables each alternative for
+ different operands to be visually aligned in the machine
+ description even if they have different number of constraints and
+ modifiers.
+
+`m'
+ A memory operand is allowed, with any kind of address that the
+ machine supports in general.
+
+`o'
+ A memory operand is allowed, but only if the address is
+ "offsettable". This means that adding a small integer (actually,
+ the width in bytes of the operand, as determined by its machine
+ mode) may be added to the address and the result is also a valid
+ memory address.
+
+ For example, an address which is constant is offsettable; so is an
+ address that is the sum of a register and a constant (as long as a
+ slightly larger constant is also within the range of
+ address-offsets supported by the machine); but an autoincrement or
+ autodecrement address is not offsettable. More complicated
+ indirect/indexed addresses may or may not be offsettable depending
+ on the other addressing modes that the machine supports.
+
+ Note that in an output operand which can be matched by another
+ operand, the constraint letter `o' is valid only when accompanied
+ by both `<' (if the target machine has predecrement addressing)
+ and `>' (if the target machine has preincrement addressing).
+
+`V'
+ A memory operand that is not offsettable. In other words,
+ anything that would fit the `m' constraint but not the `o'
+ constraint.
+
+`<'
+ A memory operand with autodecrement addressing (either
+ predecrement or postdecrement) is allowed.
+
+`>'
+ A memory operand with autoincrement addressing (either
+ preincrement or postincrement) is allowed.
+
+`r'
+ A register operand is allowed provided that it is in a general
+ register.
+
+`i'
+ An immediate integer operand (one with constant value) is allowed.
+ This includes symbolic constants whose values will be known only at
+ assembly time.
+
+`n'
+ An immediate integer operand with a known numeric value is allowed.
+ Many systems cannot support assembly-time constants for operands
+ less than a word wide. Constraints for these operands should use
+ `n' rather than `i'.
+
+`I', `J', `K', ... `P'
+ Other letters in the range `I' through `P' may be defined in a
+ machine-dependent fashion to permit immediate integer operands with
+ explicit integer values in specified ranges. For example, on the
+ 68000, `I' is defined to stand for the range of values 1 to 8.
+ This is the range permitted as a shift count in the shift
+ instructions.
+
+`E'
+ An immediate floating operand (expression code `const_double') is
+ allowed, but only if the target floating point format is the same
+ as that of the host machine (on which the compiler is running).
+
+`F'
+ An immediate floating operand (expression code `const_double') is
+ allowed.
+
+`G', `H'
+ `G' and `H' may be defined in a machine-dependent fashion to
+ permit immediate floating operands in particular ranges of values.
+
+`s'
+ An immediate integer operand whose value is not an explicit
+ integer is allowed.
+
+ This might appear strange; if an insn allows a constant operand
+ with a value not known at compile time, it certainly must allow
+ any known value. So why use `s' instead of `i'? Sometimes it
+ allows better code to be generated.
+
+ For example, on the 68000 in a fullword instruction it is possible
+ to use an immediate operand; but if the immediate value is between
+ -128 and 127, better code results from loading the value into a
+ register and using the register. This is because the load into
+ the register can be done with a `moveq' instruction. We arrange
+ for this to happen by defining the letter `K' to mean "any integer
+ outside the range -128 to 127", and then specifying `Ks' in the
+ operand constraints.
+
+`g'
+ Any register, memory or immediate integer operand is allowed,
+ except for registers that are not general registers.
+
+`X'
+ Any operand whatsoever is allowed, even if it does not satisfy
+ `general_operand'. This is normally used in the constraint of a
+ `match_scratch' when certain alternatives will not actually
+ require a scratch register.
+
+`0', `1', `2', ... `9'
+ An operand that matches the specified operand number is allowed.
+ If a digit is used together with letters within the same
+ alternative, the digit should come last.
+
+ This number is allowed to be more than a single digit. If multiple
+ digits are encountered consecutavely, they are interpreted as a
+ single decimal integer. There is scant chance for ambiguity,
+ since to-date it has never been desirable that `10' be interpreted
+ as matching either operand 1 _or_ operand 0. Should this be
+ desired, one can use multiple alternatives instead.
+
+ This is called a "matching constraint" and what it really means is
+ that the assembler has only a single operand that fills two roles
+ considered separate in the RTL insn. For example, an add insn has
+ two input operands and one output operand in the RTL, but on most
+ CISC machines an add instruction really has only two operands, one
+ of them an input-output operand:
+
+ addl #35,r12
+
+ Matching constraints are used in these circumstances. More
+ precisely, the two operands that match must include one input-only
+ operand and one output-only operand. Moreover, the digit must be a
+ smaller number than the number of the operand that uses it in the
+ constraint.
+
+ For operands to match in a particular case usually means that they
+ are identical-looking RTL expressions. But in a few special cases
+ specific kinds of dissimilarity are allowed. For example, `*x' as
+ an input operand will match `*x++' as an output operand. For
+ proper results in such cases, the output template should always
+ use the output-operand's number when printing the operand.
+
+`p'
+ An operand that is a valid memory address is allowed. This is for
+ "load address" and "push address" instructions.
+
+ `p' in the constraint must be accompanied by `address_operand' as
+ the predicate in the `match_operand'. This predicate interprets
+ the mode specified in the `match_operand' as the mode of the memory
+ reference for which the address would be valid.
+
+OTHER-LETTERS
+ Other letters can be defined in machine-dependent fashion to stand
+ for particular classes of registers or other arbitrary operand
+ types. `d', `a' and `f' are defined on the 68000/68020 to stand
+ for data, address and floating point registers.
+
+ The machine description macro `REG_CLASS_FROM_LETTER' has first
+ cut at the otherwise unused letters. If it evaluates to `NO_REGS',
+ then `EXTRA_CONSTRAINT' is evaluated.
+
+ A typical use for `EXTRA_CONSTRANT' would be to distinguish certain
+ types of memory references that affect other insn operands.
+
+ In order to have valid assembler code, each operand must satisfy its
+constraint. But a failure to do so does not prevent the pattern from
+applying to an insn. Instead, it directs the compiler to modify the
+code so that the constraint will be satisfied. Usually this is done by
+copying an operand into a register.
+
+ Contrast, therefore, the two instruction patterns that follow:
+
+ (define_insn ""
+ [(set (match_operand:SI 0 "general_operand" "=r")
+ (plus:SI (match_dup 0)
+ (match_operand:SI 1 "general_operand" "r")))]
+ ""
+ "...")
+
+which has two operands, one of which must appear in two places, and
+
+ (define_insn ""
+ [(set (match_operand:SI 0 "general_operand" "=r")
+ (plus:SI (match_operand:SI 1 "general_operand" "0")
+ (match_operand:SI 2 "general_operand" "r")))]
+ ""
+ "...")
+
+which has three operands, two of which are required by a constraint to
+be identical. If we are considering an insn of the form
+
+ (insn N PREV NEXT
+ (set (reg:SI 3)
+ (plus:SI (reg:SI 6) (reg:SI 109)))
+ ...)
+
+the first pattern would not apply at all, because this insn does not
+contain two identical subexpressions in the right place. The pattern
+would say, "That does not look like an add instruction; try other
+patterns." The second pattern would say, "Yes, that's an add
+instruction, but there is something wrong with it." It would direct
+the reload pass of the compiler to generate additional insns to make
+the constraint true. The results might look like this:
+
+ (insn N2 PREV N
+ (set (reg:SI 3) (reg:SI 6))
+ ...)
+
+ (insn N N2 NEXT
+ (set (reg:SI 3)
+ (plus:SI (reg:SI 3) (reg:SI 109)))
+ ...)
+
+ It is up to you to make sure that each operand, in each pattern, has
+constraints that can handle any RTL expression that could be present for
+that operand. (When multiple alternatives are in use, each pattern
+must, for each possible combination of operand expressions, have at
+least one alternative which can handle that combination of operands.)
+The constraints don't need to _allow_ any possible operand--when this is
+the case, they do not constrain--but they must at least point the way to
+reloading any possible operand so that it will fit.
+
+ * If the constraint accepts whatever operands the predicate permits,
+ there is no problem: reloading is never necessary for this operand.
+
+ For example, an operand whose constraints permit everything except
+ registers is safe provided its predicate rejects registers.
+
+ An operand whose predicate accepts only constant values is safe
+ provided its constraints include the letter `i'. If any possible
+ constant value is accepted, then nothing less than `i' will do; if
+ the predicate is more selective, then the constraints may also be
+ more selective.
+
+ * Any operand expression can be reloaded by copying it into a
+ register. So if an operand's constraints allow some kind of
+ register, it is certain to be safe. It need not permit all
+ classes of registers; the compiler knows how to copy a register
+ into another register of the proper class in order to make an
+ instruction valid.
+
+ * A nonoffsettable memory reference can be reloaded by copying the
+ address into a register. So if the constraint uses the letter
+ `o', all memory references are taken care of.
+
+ * A constant operand can be reloaded by allocating space in memory to
+ hold it as preinitialized data. Then the memory reference can be
+ used in place of the constant. So if the constraint uses the
+ letters `o' or `m', constant operands are not a problem.
+
+ * If the constraint permits a constant and a pseudo register used in
+ an insn was not allocated to a hard register and is equivalent to
+ a constant, the register will be replaced with the constant. If
+ the predicate does not permit a constant and the insn is
+ re-recognized for some reason, the compiler will crash. Thus the
+ predicate must always recognize any objects allowed by the
+ constraint.
+
+ If the operand's predicate can recognize registers, but the
+constraint does not permit them, it can make the compiler crash. When
+this operand happens to be a register, the reload pass will be stymied,
+because it does not know how to copy a register temporarily into memory.
+
+ If the predicate accepts a unary operator, the constraint applies to
+the operand. For example, the MIPS processor at ISA level 3 supports an
+instruction which adds two registers in `SImode' to produce a `DImode'
+result, but only if the registers are correctly sign extended. This
+predicate for the input operands accepts a `sign_extend' of an `SImode'
+register. Write the constraint to indicate the type of register that
+is required for the operand of the `sign_extend'.
+
+\1f
+File: gccint.info, Node: Multi-Alternative, Next: Class Preferences, Prev: Simple Constraints, Up: Constraints
+
+9.7.2 Multiple Alternative Constraints
+--------------------------------------
+
+Sometimes a single instruction has multiple alternative sets of possible
+operands. For example, on the 68000, a logical-or instruction can
+combine register or an immediate value into memory, or it can combine
+any kind of operand into a register; but it cannot combine one memory
+location into another.
+
+ These constraints are represented as multiple alternatives. An
+alternative can be described by a series of letters for each operand.
+The overall constraint for an operand is made from the letters for this
+operand from the first alternative, a comma, the letters for this
+operand from the second alternative, a comma, and so on until the last
+alternative. Here is how it is done for fullword logical-or on the
+68000:
+
+ (define_insn "iorsi3"
+ [(set (match_operand:SI 0 "general_operand" "=m,d")
+ (ior:SI (match_operand:SI 1 "general_operand" "%0,0")
+ (match_operand:SI 2 "general_operand" "dKs,dmKs")))]
+ ...)
+
+ The first alternative has `m' (memory) for operand 0, `0' for
+operand 1 (meaning it must match operand 0), and `dKs' for operand 2.
+The second alternative has `d' (data register) for operand 0, `0' for
+operand 1, and `dmKs' for operand 2. The `=' and `%' in the
+constraints apply to all the alternatives; their meaning is explained
+in the next section (*note Class Preferences::).
+
+ If all the operands fit any one alternative, the instruction is
+valid. Otherwise, for each alternative, the compiler counts how many
+instructions must be added to copy the operands so that that
+alternative applies. The alternative requiring the least copying is
+chosen. If two alternatives need the same amount of copying, the one
+that comes first is chosen. These choices can be altered with the `?'
+and `!' characters:
+
+`?'
+ Disparage slightly the alternative that the `?' appears in, as a
+ choice when no alternative applies exactly. The compiler regards
+ this alternative as one unit more costly for each `?' that appears
+ in it.
+
+`!'
+ Disparage severely the alternative that the `!' appears in. This
+ alternative can still be used if it fits without reloading, but if
+ reloading is needed, some other alternative will be used.
+
+ When an insn pattern has multiple alternatives in its constraints,
+often the appearance of the assembler code is determined mostly by which
+alternative was matched. When this is so, the C code for writing the
+assembler code can use the variable `which_alternative', which is the
+ordinal number of the alternative that was actually satisfied (0 for
+the first, 1 for the second alternative, etc.). *Note Output
+Statement::.
+
+\1f
+File: gccint.info, Node: Class Preferences, Next: Modifiers, Prev: Multi-Alternative, Up: Constraints
+
+9.7.3 Register Class Preferences
+--------------------------------
+
+The operand constraints have another function: they enable the compiler
+to decide which kind of hardware register a pseudo register is best
+allocated to. The compiler examines the constraints that apply to the
+insns that use the pseudo register, looking for the machine-dependent
+letters such as `d' and `a' that specify classes of registers. The
+pseudo register is put in whichever class gets the most "votes". The
+constraint letters `g' and `r' also vote: they vote in favor of a
+general register. The machine description says which registers are
+considered general.
+
+ Of course, on some machines all registers are equivalent, and no
+register classes are defined. Then none of this complexity is relevant.
+
+\1f
+File: gccint.info, Node: Modifiers, Next: Machine Constraints, Prev: Class Preferences, Up: Constraints
+
+9.7.4 Constraint Modifier Characters
+------------------------------------
+
+Here are constraint modifier characters.
+
+`='
+ Means that this operand is write-only for this instruction: the
+ previous value is discarded and replaced by output data.
+
+`+'
+ Means that this operand is both read and written by the
+ instruction.
+
+ When the compiler fixes up the operands to satisfy the constraints,
+ it needs to know which operands are inputs to the instruction and
+ which are outputs from it. `=' identifies an output; `+'
+ identifies an operand that is both input and output; all other
+ operands are assumed to be input only.
+
+ If you specify `=' or `+' in a constraint, you put it in the first
+ character of the constraint string.
+
+`&'
+ Means (in a particular alternative) that this operand is an
+ "earlyclobber" operand, which is modified before the instruction is
+ finished using the input operands. Therefore, this operand may
+ not lie in a register that is used as an input operand or as part
+ of any memory address.
+
+ `&' applies only to the alternative in which it is written. In
+ constraints with multiple alternatives, sometimes one alternative
+ requires `&' while others do not. See, for example, the `movdf'
+ insn of the 68000.
+
+ An input operand can be tied to an earlyclobber operand if its only
+ use as an input occurs before the early result is written. Adding
+ alternatives of this form often allows GCC to produce better code
+ when only some of the inputs can be affected by the earlyclobber.
+ See, for example, the `mulsi3' insn of the ARM.
+
+ `&' does not obviate the need to write `='.
+
+`%'
+ Declares the instruction to be commutative for this operand and the
+ following operand. This means that the compiler may interchange
+ the two operands if that is the cheapest way to make all operands
+ fit the constraints. This is often used in patterns for addition
+ instructions that really have only two operands: the result must
+ go in one of the arguments. Here for example, is how the 68000
+ halfword-add instruction is defined:
+
+ (define_insn "addhi3"
+ [(set (match_operand:HI 0 "general_operand" "=m,r")
+ (plus:HI (match_operand:HI 1 "general_operand" "%0,0")
+ (match_operand:HI 2 "general_operand" "di,g")))]
+ ...)
+
+`#'
+ Says that all following characters, up to the next comma, are to be
+ ignored as a constraint. They are significant only for choosing
+ register preferences.
+
+`*'
+ Says that the following character should be ignored when choosing
+ register preferences. `*' has no effect on the meaning of the
+ constraint as a constraint, and no effect on reloading.
+
+ Here is an example: the 68000 has an instruction to sign-extend a
+ halfword in a data register, and can also sign-extend a value by
+ copying it into an address register. While either kind of
+ register is acceptable, the constraints on an address-register
+ destination are less strict, so it is best if register allocation
+ makes an address register its goal. Therefore, `*' is used so
+ that the `d' constraint letter (for data register) is ignored when
+ computing register preferences.
+
+ (define_insn "extendhisi2"
+ [(set (match_operand:SI 0 "general_operand" "=*d,a")
+ (sign_extend:SI
+ (match_operand:HI 1 "general_operand" "0,g")))]
+ ...)
+
+\1f
+File: gccint.info, Node: Machine Constraints, Prev: Modifiers, Up: Constraints
+
+9.7.5 Constraints for Particular Machines
+-----------------------------------------
+
+Whenever possible, you should use the general-purpose constraint letters
+in `asm' arguments, since they will convey meaning more readily to
+people reading your code. Failing that, use the constraint letters
+that usually have very similar meanings across architectures. The most
+commonly used constraints are `m' and `r' (for memory and
+general-purpose registers respectively; *note Simple Constraints::), and
+`I', usually the letter indicating the most common immediate-constant
+format.
+
+ For each machine architecture, the `config/MACHINE/MACHINE.h' file
+defines additional constraints. These constraints are used by the
+compiler itself for instruction generation, as well as for `asm'
+statements; therefore, some of the constraints are not particularly
+interesting for `asm'. The constraints are defined through these
+macros:
+
+`REG_CLASS_FROM_LETTER'
+ Register class constraints (usually lower case).
+
+`CONST_OK_FOR_LETTER_P'
+ Immediate constant constraints, for non-floating point constants of
+ word size or smaller precision (usually upper case).
+
+`CONST_DOUBLE_OK_FOR_LETTER_P'
+ Immediate constant constraints, for all floating point constants
+ and for constants of greater than word size precision (usually
+ upper case).
+
+`EXTRA_CONSTRAINT'
+ Special cases of registers or memory. This macro is not required,
+ and is only defined for some machines.
+
+ Inspecting these macro definitions in the compiler source for your
+machine is the best way to be certain you have the right constraints.
+However, here is a summary of the machine-dependent constraints
+available on some particular machines.
+
+_ARM family--`arm.h'_
+
+ `f'
+ Floating-point register
+
+ `F'
+ One of the floating-point constants 0.0, 0.5, 1.0, 2.0, 3.0,
+ 4.0, 5.0 or 10.0
+
+ `G'
+ Floating-point constant that would satisfy the constraint `F'
+ if it were negated
+
+ `I'
+ Integer that is valid as an immediate operand in a data
+ processing instruction. That is, an integer in the range 0
+ to 255 rotated by a multiple of 2
+
+ `J'
+ Integer in the range -4095 to 4095
+
+ `K'
+ Integer that satisfies constraint `I' when inverted (ones
+ complement)
+
+ `L'
+ Integer that satisfies constraint `I' when negated (twos
+ complement)
+
+ `M'
+ Integer in the range 0 to 32
+
+ `Q'
+ A memory reference where the exact address is in a single
+ register (``m'' is preferable for `asm' statements)
+
+ `R'
+ An item in the constant pool
+
+ `S'
+ A symbol in the text segment of the current file
+
+_AMD 29000 family--`a29k.h'_
+
+ `l'
+ Local register 0
+
+ `b'
+ Byte Pointer (`BP') register
+
+ `q'
+ `Q' register
+
+ `h'
+ Special purpose register
+
+ `A'
+ First accumulator register
+
+ `a'
+ Other accumulator register
+
+ `f'
+ Floating point register
+
+ `I'
+ Constant greater than 0, less than 0x100
+
+ `J'
+ Constant greater than 0, less than 0x10000
+
+ `K'
+ Constant whose high 24 bits are on (1)
+
+ `L'
+ 16-bit constant whose high 8 bits are on (1)
+
+ `M'
+ 32-bit constant whose high 16 bits are on (1)
+
+ `N'
+ 32-bit negative constant that fits in 8 bits
+
+ `O'
+ The constant 0x80000000 or, on the 29050, any 32-bit constant
+ whose low 16 bits are 0.
+
+ `P'
+ 16-bit negative constant that fits in 8 bits
+
+ `G'
+ `H'
+ A floating point constant (in `asm' statements, use the
+ machine independent `E' or `F' instead)
+
+_AVR family--`avr.h'_
+
+ `l'
+ Registers from r0 to r15
+
+ `a'
+ Registers from r16 to r23
+
+ `d'
+ Registers from r16 to r31
+
+ `w'
+ Registers from r24 to r31. These registers can be used in
+ `adiw' command
+
+ `e'
+ Pointer register (r26-r31)
+
+ `b'
+ Base pointer register (r28-r31)
+
+ `q'
+ Stack pointer register (SPH:SPL)
+
+ `t'
+ Temporary register r0
+
+ `x'
+ Register pair X (r27:r26)
+
+ `y'
+ Register pair Y (r29:r28)
+
+ `z'
+ Register pair Z (r31:r30)
+
+ `I'
+ Constant greater than -1, less than 64
+
+ `J'
+ Constant greater than -64, less than 1
+
+ `K'
+ Constant integer 2
+
+ `L'
+ Constant integer 0
+
+ `M'
+ Constant that fits in 8 bits
+
+ `N'
+ Constant integer -1
+
+ `O'
+ Constant integer 8, 16, or 24
+
+ `P'
+ Constant integer 1
+
+ `G'
+ A floating point constant 0.0
+
+_IBM RS6000--`rs6000.h'_
+
+ `b'
+ Address base register
+
+ `f'
+ Floating point register
+
+ `h'
+ `MQ', `CTR', or `LINK' register
+
+ `q'
+ `MQ' register
+
+ `c'
+ `CTR' register
+
+ `l'
+ `LINK' register
+
+ `x'
+ `CR' register (condition register) number 0
+
+ `y'
+ `CR' register (condition register)
+
+ `z'
+ `FPMEM' stack memory for FPR-GPR transfers
+
+ `I'
+ Signed 16-bit constant
+
+ `J'
+ Unsigned 16-bit constant shifted left 16 bits (use `L'
+ instead for `SImode' constants)
+
+ `K'
+ Unsigned 16-bit constant
+
+ `L'
+ Signed 16-bit constant shifted left 16 bits
+
+ `M'
+ Constant larger than 31
+
+ `N'
+ Exact power of 2
+
+ `O'
+ Zero
+
+ `P'
+ Constant whose negation is a signed 16-bit constant
+
+ `G'
+ Floating point constant that can be loaded into a register
+ with one instruction per word
+
+ `Q'
+ Memory operand that is an offset from a register (`m' is
+ preferable for `asm' statements)
+
+ `R'
+ AIX TOC entry
+
+ `S'
+ Constant suitable as a 64-bit mask operand
+
+ `T'
+ Constant suitable as a 32-bit mask operand
+
+ `U'
+ System V Release 4 small data area reference
+
+_Intel 386--`i386.h'_
+
+ `q'
+ `a', `b', `c', or `d' register for the i386. For x86-64 it
+ is equivalent to `r' class. (for 8-bit instructions that do
+ not use upper halves)
+
+ `Q'
+ `a', `b', `c', or `d' register. (for 8-bit instructions, that
+ do use upper halves)
+
+ `R'
+ Legacy register--equivalent to `r' class in i386 mode. (for
+ non-8-bit registers used together with 8-bit upper halves in
+ a single instruction)
+
+ `A'
+ Specifies the `a' or `d' registers. This is primarily useful
+ for 64-bit integer values (when in 32-bit mode) intended to
+ be returned with the `d' register holding the most
+ significant bits and the `a' register holding the least
+ significant bits.
+
+ `f'
+ Floating point register
+
+ `t'
+ First (top of stack) floating point register
+
+ `u'
+ Second floating point register
+
+ `a'
+ `a' register
+
+ `b'
+ `b' register
+
+ `c'
+ `c' register
+
+ `d'
+ `d' register
+
+ `D'
+ `di' register
+
+ `S'
+ `si' register
+
+ `x'
+ `xmm' SSE register
+
+ `y'
+ MMX register
+
+ `I'
+ Constant in range 0 to 31 (for 32-bit shifts)
+
+ `J'
+ Constant in range 0 to 63 (for 64-bit shifts)
+
+ `K'
+ `0xff'
+
+ `L'
+ `0xffff'
+
+ `M'
+ 0, 1, 2, or 3 (shifts for `lea' instruction)
+
+ `N'
+ Constant in range 0 to 255 (for `out' instruction)
+
+ `Z'
+ Constant in range 0 to `0xffffffff' or symbolic reference
+ known to fit specified range. (for using immediates in zero
+ extending 32-bit to 64-bit x86-64 instructions)
+
+ `e'
+ Constant in range -2147483648 to 2147483647 or symbolic
+ reference known to fit specified range. (for using
+ immediates in 64-bit x86-64 instructions)
+
+ `G'
+ Standard 80387 floating point constant
+
+_Intel 960--`i960.h'_
+
+ `f'
+ Floating point register (`fp0' to `fp3')
+
+ `l'
+ Local register (`r0' to `r15')
+
+ `b'
+ Global register (`g0' to `g15')
+
+ `d'
+ Any local or global register
+
+ `I'
+ Integers from 0 to 31
+
+ `J'
+ 0
+
+ `K'
+ Integers from -31 to 0
+
+ `G'
+ Floating point 0
+
+ `H'
+ Floating point 1
+
+_MIPS--`mips.h'_
+
+ `d'
+ General-purpose integer register
+
+ `f'
+ Floating-point register (if available)
+
+ `h'
+ `Hi' register
+
+ `l'
+ `Lo' register
+
+ `x'
+ `Hi' or `Lo' register
+
+ `y'
+ General-purpose integer register
+
+ `z'
+ Floating-point status register
+
+ `I'
+ Signed 16-bit constant (for arithmetic instructions)
+
+ `J'
+ Zero
+
+ `K'
+ Zero-extended 16-bit constant (for logic instructions)
+
+ `L'
+ Constant with low 16 bits zero (can be loaded with `lui')
+
+ `M'
+ 32-bit constant which requires two instructions to load (a
+ constant which is not `I', `K', or `L')
+
+ `N'
+ Negative 16-bit constant
+
+ `O'
+ Exact power of two
+
+ `P'
+ Positive 16-bit constant
+
+ `G'
+ Floating point zero
+
+ `Q'
+ Memory reference that can be loaded with more than one
+ instruction (`m' is preferable for `asm' statements)
+
+ `R'
+ Memory reference that can be loaded with one instruction (`m'
+ is preferable for `asm' statements)
+
+ `S'
+ Memory reference in external OSF/rose PIC format (`m' is
+ preferable for `asm' statements)
+
+_Motorola 680x0--`m68k.h'_
+
+ `a'
+ Address register
+
+ `d'
+ Data register
+
+ `f'
+ 68881 floating-point register, if available
+
+ `x'
+ Sun FPA (floating-point) register, if available
+
+ `y'
+ First 16 Sun FPA registers, if available
+
+ `I'
+ Integer in the range 1 to 8
+
+ `J'
+ 16-bit signed number
+
+ `K'
+ Signed number whose magnitude is greater than 0x80
+
+ `L'
+ Integer in the range -8 to -1
+
+ `M'
+ Signed number whose magnitude is greater than 0x100
+
+ `G'
+ Floating point constant that is not a 68881 constant
+
+ `H'
+ Floating point constant that can be used by Sun FPA
+
+_Motorola 68HC11 & 68HC12 families--`m68hc11.h'_
+
+ `a'
+ Register 'a'
+
+ `b'
+ Register 'b'
+
+ `d'
+ Register 'd'
+
+ `q'
+ An 8-bit register
+
+ `t'
+ Temporary soft register _.tmp
+
+ `u'
+ A soft register _.d1 to _.d31
+
+ `w'
+ Stack pointer register
+
+ `x'
+ Register 'x'
+
+ `y'
+ Register 'y'
+
+ `z'
+ Pseudo register 'z' (replaced by 'x' or 'y' at the end)
+
+ `A'
+ An address register: x, y or z
+
+ `B'
+ An address register: x or y
+
+ `D'
+ Register pair (x:d) to form a 32-bit value
+
+ `L'
+ Constants in the range -65536 to 65535
+
+ `M'
+ Constants whose 16-bit low part is zero
+
+ `N'
+ Constant integer 1 or -1
+
+ `O'
+ Constant integer 16
+
+ `P'
+ Constants in the range -8 to 2
+
+
+_SPARC--`sparc.h'_
+
+ `f'
+ Floating-point register that can hold 32- or 64-bit values.
+
+ `e'
+ Floating-point register that can hold 64- or 128-bit values.
+
+ `I'
+ Signed 13-bit constant
+
+ `J'
+ Zero
+
+ `K'
+ 32-bit constant with the low 12 bits clear (a constant that
+ can be loaded with the `sethi' instruction)
+
+ `L'
+ A constant in the range supported by `movcc' instructions
+
+ `M'
+ A constant in the range supported by `movrcc' instructions
+
+ `N'
+ Same as `K', except that it verifies that bits that are not
+ in the lower 32-bit range are all zero. Must be used instead
+ of `K' for modes wider than `SImode'
+
+ `G'
+ Floating-point zero
+
+ `H'
+ Signed 13-bit constant, sign-extended to 32 or 64 bits
+
+ `Q'
+ Floating-point constant whose integral representation can be
+ moved into an integer register using a single sethi
+ instruction
+
+ `R'
+ Floating-point constant whose integral representation can be
+ moved into an integer register using a single mov instruction
+
+ `S'
+ Floating-point constant whose integral representation can be
+ moved into an integer register using a high/lo_sum
+ instruction sequence
+
+ `T'
+ Memory address aligned to an 8-byte boundary
+
+ `U'
+ Even register
+
+ `W'
+ Memory address for `e' constraint registers.
+
+
+_TMS320C3x/C4x--`c4x.h'_
+
+ `a'
+ Auxiliary (address) register (ar0-ar7)
+
+ `b'
+ Stack pointer register (sp)
+
+ `c'
+ Standard (32-bit) precision integer register
+
+ `f'
+ Extended (40-bit) precision register (r0-r11)
+
+ `k'
+ Block count register (bk)
+
+ `q'
+ Extended (40-bit) precision low register (r0-r7)
+
+ `t'
+ Extended (40-bit) precision register (r0-r1)
+
+ `u'
+ Extended (40-bit) precision register (r2-r3)
+
+ `v'
+ Repeat count register (rc)
- A back end for a target architecture in GCC has the following parts:
+ `x'
+ Index register (ir0-ir1)
- * A directory `MACHINE' under `gcc/config', containing a machine
- description `MACHINE.md' file (*note Machine Descriptions: Machine
- Desc.), header files `MACHINE.h' and `MACHINE-protos.h' and a
- source file `MACHINE.c' (*note Target Description Macros and
- Functions: Target Macros.), possibly a target Makefile fragment
- `t-MACHINE' (*note The Target Makefile Fragment: Target
- Fragment.), and maybe some other files. The names of these files
- may be changed from the defaults given by explicit specifications
- in `config.gcc'.
+ `y'
+ Status (condition code) register (st)
- * Entries in `config.gcc' (*note The `config.gcc' File: System
- Config.) for the systems with this target architecture.
+ `z'
+ Data page register (dp)
- * Documentation in `gcc/doc/invoke.texi' for any command-line
- options supported by this target (*note Run-time Target
- Specification: Run-time Target.). This means both entries in the
- summary table of options and details of the individual options.
+ `G'
+ Floating-point zero
- * Documentation in `gcc/doc/extend.texi' for any target-specific
- attributes supported (*note Defining target-specific uses of
- `__attribute__': Target Attributes.), including where the same
- attribute is already supported on some targets, which are
- enumerated in the manual.
+ `H'
+ Immediate 16-bit floating-point constant
- * Documentation in `gcc/doc/extend.texi' for any target-specific
- pragmas supported.
+ `I'
+ Signed 16-bit constant
- * Documentation in `gcc/doc/extend.texi' of any target-specific
- built-in functions supported.
+ `J'
+ Signed 8-bit constant
- * Documentation in `gcc/doc/md.texi' of any target-specific
- constraint letters (*note Constraints for Particular Machines:
- Machine Constraints.).
+ `K'
+ Signed 5-bit constant
- * A note in `gcc/doc/contrib.texi' under the person or people who
- contributed the target support.
+ `L'
+ Unsigned 16-bit constant
- * Entries in `gcc/doc/install.texi' for all target triplets
- supported with this target architecture, giving details of any
- special notes about installation for this target, or saying that
- there are no special notes if there are none.
+ `M'
+ Unsigned 8-bit constant
- * Possibly other support outside the `gcc' directory for runtime
- libraries. FIXME: reference docs for this. The libstdc++ porting
- manual needs to be installed as info for this to work, or to be a
- chapter of this manual.
+ `N'
+ Ones complement of unsigned 16-bit constant
- If the back end is added to the official GCC CVS repository, the
-following are also necessary:
+ `O'
+ High 16-bit constant (32-bit constant with 16 LSBs zero)
- * An entry for the target architecture in `readings.html' on the GCC
- web site, with any relevant links.
+ `Q'
+ Indirect memory reference with signed 8-bit or index register
+ displacement
- * A news item about the contribution of support for that target
- architecture, in `index.html' on the GCC web site.
+ `R'
+ Indirect memory reference with unsigned 5-bit displacement
- * Normally, one or more maintainers of that target listed in
- `MAINTAINERS'. Some existing architectures may be unmaintained,
- but it would be unusual to add support for a target that does not
- have a maintainer when support is added.
+ `S'
+ Indirect memory reference with 1 bit or index register
+ displacement
+
+ `T'
+ Direct memory reference
+
+ `U'
+ Symbolic address
+
+
+_S/390 and zSeries--`s390.h'_
+
+ `a'
+ Address register (general purpose register except r0)
+
+ `d'
+ Data register (arbitrary general purpose register)
+
+ `f'
+ Floating-point register
+
+ `I'
+ Unsigned 8-bit constant (0-255)
+
+ `J'
+ Unsigned 12-bit constant (0-4095)
+
+ `K'
+ Signed 16-bit constant (-32768-32767)
+
+ `L'
+ Unsigned 16-bit constant (0-65535)
+
+ `Q'
+ Memory reference without index register
+
+ `S'
+ Symbolic constant suitable for use with the `larl' instruction
+
+
+_Xstormy16--`stormy16.h'_
+
+ `a'
+ Register r0.
+
+ `b'
+ Register r1.
+
+ `c'
+ Register r2.
+
+ `d'
+ Register r8.
+
+ `e'
+ Registers r0 through r7.
+
+ `t'
+ Registers r0 and r1.
+
+ `y'
+ The carry register.
+
+ `z'
+ Registers r8 and r9.
+
+ `I'
+ A constant between 0 and 3 inclusive.
+
+ `J'
+ A constant that has exactly one bit set.
+
+ `K'
+ A constant that has exactly one bit clear.
+
+ `L'
+ A constant between 0 and 255 inclusive.
+
+ `M'
+ A constant between -255 and 0 inclusive.
+
+ `N'
+ A constant between -3 and 0 inclusive.
+
+ `O'
+ A constant between 1 and 4 inclusive.
+
+ `P'
+ A constant between -4 and -1 inclusive.
+
+ `Q'
+ A memory reference that is a stack push.
+
+ `R'
+ A memory reference that is a stack pop.
+
+ `S'
+ A memory reference that refers to an constant address of
+ known value.
+
+ `T'
+ The register indicated by Rx (not implemented yet).
+
+ `U'
+ A constant that is not between 2 and 15 inclusive.
+
+
+_Xtensa--`xtensa.h'_
+
+ `a'
+ General-purpose 32-bit register
+
+ `b'
+ One-bit boolean register
+
+ `A'
+ MAC16 40-bit accumulator register
+
+ `I'
+ Signed 12-bit integer constant, for use in MOVI instructions
+
+ `J'
+ Signed 8-bit integer constant, for use in ADDI instructions
+
+ `K'
+ Integer constant valid for BccI instructions
+
+ `L'
+ Unsigned constant valid for BccUI instructions
+
+
+
+\1f
+File: gccint.info, Node: Standard Names, Next: Pattern Ordering, Prev: Constraints, Up: Machine Desc
+
+9.8 Standard Pattern Names For Generation
+=========================================
+
+Here is a table of the instruction names that are meaningful in the RTL
+generation pass of the compiler. Giving one of these names to an
+instruction pattern tells the RTL generation pass that it can use the
+pattern to accomplish a certain task.
+
+`movM'
+ Here M stands for a two-letter machine mode name, in lower case.
+ This instruction pattern moves data with that machine mode from
+ operand 1 to operand 0. For example, `movsi' moves full-word data.
+
+ If operand 0 is a `subreg' with mode M of a register whose own
+ mode is wider than M, the effect of this instruction is to store
+ the specified value in the part of the register that corresponds
+ to mode M. Bits outside of M, but which are within the same
+ target word as the `subreg' are undefined. Bits which are outside
+ the target word are left unchanged.
+
+ This class of patterns is special in several ways. First of all,
+ each of these names up to and including full word size _must_ be
+ defined, because there is no other way to copy a datum from one
+ place to another. If there are patterns accepting operands in
+ larger modes, `movM' must be defined for integer modes of those
+ sizes.
+
+ Second, these patterns are not used solely in the RTL generation
+ pass. Even the reload pass can generate move insns to copy values
+ from stack slots into temporary registers. When it does so, one
+ of the operands is a hard register and the other is an operand
+ that can need to be reloaded into a register.
+
+ Therefore, when given such a pair of operands, the pattern must
+ generate RTL which needs no reloading and needs no temporary
+ registers--no registers other than the operands. For example, if
+ you support the pattern with a `define_expand', then in such a
+ case the `define_expand' mustn't call `force_reg' or any other such
+ function which might generate new pseudo registers.
+
+ This requirement exists even for subword modes on a RISC machine
+ where fetching those modes from memory normally requires several
+ insns and some temporary registers.
+
+ During reload a memory reference with an invalid address may be
+ passed as an operand. Such an address will be replaced with a
+ valid address later in the reload pass. In this case, nothing may
+ be done with the address except to use it as it stands. If it is
+ copied, it will not be replaced with a valid address. No attempt
+ should be made to make such an address into a valid address and no
+ routine (such as `change_address') that will do so may be called.
+ Note that `general_operand' will fail when applied to such an
+ address.
+
+ The global variable `reload_in_progress' (which must be explicitly
+ declared if required) can be used to determine whether such special
+ handling is required.
+
+ The variety of operands that have reloads depends on the rest of
+ the machine description, but typically on a RISC machine these can
+ only be pseudo registers that did not get hard registers, while on
+ other machines explicit memory references will get optional
+ reloads.
+
+ If a scratch register is required to move an object to or from
+ memory, it can be allocated using `gen_reg_rtx' prior to life
+ analysis.
+
+ If there are cases which need scratch registers during or after
+ reload, you must define `SECONDARY_INPUT_RELOAD_CLASS' and/or
+ `SECONDARY_OUTPUT_RELOAD_CLASS' to detect them, and provide
+ patterns `reload_inM' or `reload_outM' to handle them. *Note
+ Register Classes::.
+
+ The global variable `no_new_pseudos' can be used to determine if it
+ is unsafe to create new pseudo registers. If this variable is
+ nonzero, then it is unsafe to call `gen_reg_rtx' to allocate a new
+ pseudo.
+
+ The constraints on a `movM' must permit moving any hard register
+ to any other hard register provided that `HARD_REGNO_MODE_OK'
+ permits mode M in both registers and `REGISTER_MOVE_COST' applied
+ to their classes returns a value of 2.
+
+ It is obligatory to support floating point `movM' instructions
+ into and out of any registers that can hold fixed point values,
+ because unions and structures (which have modes `SImode' or
+ `DImode') can be in those registers and they may have floating
+ point members.
+
+ There may also be a need to support fixed point `movM'
+ instructions in and out of floating point registers.
+ Unfortunately, I have forgotten why this was so, and I don't know
+ whether it is still true. If `HARD_REGNO_MODE_OK' rejects fixed
+ point values in floating point registers, then the constraints of
+ the fixed point `movM' instructions must be designed to avoid ever
+ trying to reload into a floating point register.
+
+`reload_inM'
+`reload_outM'
+ Like `movM', but used when a scratch register is required to move
+ between operand 0 and operand 1. Operand 2 describes the scratch
+ register. See the discussion of the `SECONDARY_RELOAD_CLASS'
+ macro in *note Register Classes::.
+
+ There are special restrictions on the form of the `match_operand's
+ used in these patterns. First, only the predicate for the reload
+ operand is examined, i.e., `reload_in' examines operand 1, but not
+ the predicates for operand 0 or 2. Second, there may be only one
+ alternative in the constraints. Third, only a single register
+ class letter may be used for the constraint; subsequent constraint
+ letters are ignored. As a special exception, an empty constraint
+ string matches the `ALL_REGS' register class. This may relieve
+ ports of the burden of defining an `ALL_REGS' constraint letter
+ just for these patterns.
+
+`movstrictM'
+ Like `movM' except that if operand 0 is a `subreg' with mode M of
+ a register whose natural mode is wider, the `movstrictM'
+ instruction is guaranteed not to alter any of the register except
+ the part which belongs to mode M.
+
+`load_multiple'
+ Load several consecutive memory locations into consecutive
+ registers. Operand 0 is the first of the consecutive registers,
+ operand 1 is the first memory location, and operand 2 is a
+ constant: the number of consecutive registers.
+
+ Define this only if the target machine really has such an
+ instruction; do not define this if the most efficient way of
+ loading consecutive registers from memory is to do them one at a
+ time.
+
+ On some machines, there are restrictions as to which consecutive
+ registers can be stored into memory, such as particular starting or
+ ending register numbers or only a range of valid counts. For those
+ machines, use a `define_expand' (*note Expander Definitions::) and
+ make the pattern fail if the restrictions are not met.
+
+ Write the generated insn as a `parallel' with elements being a
+ `set' of one register from the appropriate memory location (you may
+ also need `use' or `clobber' elements). Use a `match_parallel'
+ (*note RTL Template::) to recognize the insn. See `a29k.md' and
+ `rs6000.md' for examples of the use of this insn pattern.
+
+`store_multiple'
+ Similar to `load_multiple', but store several consecutive registers
+ into consecutive memory locations. Operand 0 is the first of the
+ consecutive memory locations, operand 1 is the first register, and
+ operand 2 is a constant: the number of consecutive registers.
+
+`pushM'
+ Output an push instruction. Operand 0 is value to push. Used
+ only when `PUSH_ROUNDING' is defined. For historical reason, this
+ pattern may be missing and in such case an `mov' expander is used
+ instead, with a `MEM' expression forming the push operation. The
+ `mov' expander method is deprecated.
+
+`addM3'
+ Add operand 2 and operand 1, storing the result in operand 0. All
+ operands must have mode M. This can be used even on two-address
+ machines, by means of constraints requiring operands 1 and 0 to be
+ the same location.
+
+`subM3', `mulM3'
+`divM3', `udivM3', `modM3', `umodM3'
+`sminM3', `smaxM3', `uminM3', `umaxM3'
+`andM3', `iorM3', `xorM3'
+ Similar, for other arithmetic operations.
+
+`minM3', `maxM3'
+ Floating point min and max operations. If both operands are zeros,
+ or if either operand is NaN, then it is unspecified which of the
+ two operands is returned as the result.
+
+`mulhisi3'
+ Multiply operands 1 and 2, which have mode `HImode', and store a
+ `SImode' product in operand 0.
+
+`mulqihi3', `mulsidi3'
+ Similar widening-multiplication instructions of other widths.
+
+`umulqihi3', `umulhisi3', `umulsidi3'
+ Similar widening-multiplication instructions that do unsigned
+ multiplication.
+
+`smulM3_highpart'
+ Perform a signed multiplication of operands 1 and 2, which have
+ mode M, and store the most significant half of the product in
+ operand 0. The least significant half of the product is discarded.
+
+`umulM3_highpart'
+ Similar, but the multiplication is unsigned.
+
+`divmodM4'
+ Signed division that produces both a quotient and a remainder.
+ Operand 1 is divided by operand 2 to produce a quotient stored in
+ operand 0 and a remainder stored in operand 3.
+
+ For machines with an instruction that produces both a quotient and
+ a remainder, provide a pattern for `divmodM4' but do not provide
+ patterns for `divM3' and `modM3'. This allows optimization in the
+ relatively common case when both the quotient and remainder are
+ computed.
+
+ If an instruction that just produces a quotient or just a remainder
+ exists and is more efficient than the instruction that produces
+ both, write the output routine of `divmodM4' to call
+ `find_reg_note' and look for a `REG_UNUSED' note on the quotient
+ or remainder and generate the appropriate instruction.
+
+`udivmodM4'
+ Similar, but does unsigned division.
+
+`ashlM3'
+ Arithmetic-shift operand 1 left by a number of bits specified by
+ operand 2, and store the result in operand 0. Here M is the mode
+ of operand 0 and operand 1; operand 2's mode is specified by the
+ instruction pattern, and the compiler will convert the operand to
+ that mode before generating the instruction.
+
+`ashrM3', `lshrM3', `rotlM3', `rotrM3'
+ Other shift and rotate instructions, analogous to the `ashlM3'
+ instructions.
+
+`negM2'
+ Negate operand 1 and store the result in operand 0.
+
+`absM2'
+ Store the absolute value of operand 1 into operand 0.
+
+`sqrtM2'
+ Store the square root of operand 1 into operand 0.
+
+ The `sqrt' built-in function of C always uses the mode which
+ corresponds to the C data type `double'.
+
+`ffsM2'
+ Store into operand 0 one plus the index of the least significant
+ 1-bit of operand 1. If operand 1 is zero, store zero. M is the
+ mode of operand 0; operand 1's mode is specified by the instruction
+ pattern, and the compiler will convert the operand to that mode
+ before generating the instruction.
+
+ The `ffs' built-in function of C always uses the mode which
+ corresponds to the C data type `int'.
+
+`one_cmplM2'
+ Store the bitwise-complement of operand 1 into operand 0.
+
+`cmpM'
+ Compare operand 0 and operand 1, and set the condition codes. The
+ RTL pattern should look like this:
+
+ (set (cc0) (compare (match_operand:M 0 ...)
+ (match_operand:M 1 ...)))
+
+`tstM'
+ Compare operand 0 against zero, and set the condition codes. The
+ RTL pattern should look like this:
+
+ (set (cc0) (match_operand:M 0 ...))
+
+ `tstM' patterns should not be defined for machines that do not use
+ `(cc0)'. Doing so would confuse the optimizer since it would no
+ longer be clear which `set' operations were comparisons. The
+ `cmpM' patterns should be used instead.
+
+`movstrM'
+ Block move instruction. The addresses of the destination and
+ source strings are the first two operands, and both are in mode
+ `Pmode'.
+
+ The number of bytes to move is the third operand, in mode M.
+ Usually, you specify `word_mode' for M. However, if you can
+ generate better code knowing the range of valid lengths is smaller
+ than those representable in a full word, you should provide a
+ pattern with a mode corresponding to the range of values you can
+ handle efficiently (e.g., `QImode' for values in the range 0-127;
+ note we avoid numbers that appear negative) and also a pattern
+ with `word_mode'.
+
+ The fourth operand is the known shared alignment of the source and
+ destination, in the form of a `const_int' rtx. Thus, if the
+ compiler knows that both source and destination are word-aligned,
+ it may provide the value 4 for this operand.
+
+ Descriptions of multiple `movstrM' patterns can only be beneficial
+ if the patterns for smaller modes have fewer restrictions on their
+ first, second and fourth operands. Note that the mode M in
+ `movstrM' does not impose any restriction on the mode of
+ individually moved data units in the block.
+
+ These patterns need not give special consideration to the
+ possibility that the source and destination strings might overlap.
+
+`clrstrM'
+ Block clear instruction. The addresses of the destination string
+ is the first operand, in mode `Pmode'. The number of bytes to
+ clear is the second operand, in mode M. See `movstrM' for a
+ discussion of the choice of mode.
+
+ The third operand is the known alignment of the destination, in
+ the form of a `const_int' rtx. Thus, if the compiler knows that
+ the destination is word-aligned, it may provide the value 4 for
+ this operand.
+
+ The use for multiple `clrstrM' is as for `movstrM'.
+
+`cmpstrM'
+ Block compare instruction, with five operands. Operand 0 is the
+ output; it has mode M. The remaining four operands are like the
+ operands of `movstrM'. The two memory blocks specified are
+ compared byte by byte in lexicographic order. The effect of the
+ instruction is to store a value in operand 0 whose sign indicates
+ the result of the comparison.
+
+`strlenM'
+ Compute the length of a string, with three operands. Operand 0 is
+ the result (of mode M), operand 1 is a `mem' referring to the
+ first character of the string, operand 2 is the character to
+ search for (normally zero), and operand 3 is a constant describing
+ the known alignment of the beginning of the string.
+
+`floatMN2'
+ Convert signed integer operand 1 (valid for fixed point mode M) to
+ floating point mode N and store in operand 0 (which has mode N).
+
+`floatunsMN2'
+ Convert unsigned integer operand 1 (valid for fixed point mode M)
+ to floating point mode N and store in operand 0 (which has mode N).
+
+`fixMN2'
+ Convert operand 1 (valid for floating point mode M) to fixed point
+ mode N as a signed number and store in operand 0 (which has mode
+ N). This instruction's result is defined only when the value of
+ operand 1 is an integer.
+
+`fixunsMN2'
+ Convert operand 1 (valid for floating point mode M) to fixed point
+ mode N as an unsigned number and store in operand 0 (which has
+ mode N). This instruction's result is defined only when the value
+ of operand 1 is an integer.
+
+`ftruncM2'
+ Convert operand 1 (valid for floating point mode M) to an integer
+ value, still represented in floating point mode M, and store it in
+ operand 0 (valid for floating point mode M).
+
+`fix_truncMN2'
+ Like `fixMN2' but works for any floating point value of mode M by
+ converting the value to an integer.
+
+`fixuns_truncMN2'
+ Like `fixunsMN2' but works for any floating point value of mode M
+ by converting the value to an integer.
+
+`truncMN2'
+ Truncate operand 1 (valid for mode M) to mode N and store in
+ operand 0 (which has mode N). Both modes must be fixed point or
+ both floating point.
+
+`extendMN2'
+ Sign-extend operand 1 (valid for mode M) to mode N and store in
+ operand 0 (which has mode N). Both modes must be fixed point or
+ both floating point.
+
+`zero_extendMN2'
+ Zero-extend operand 1 (valid for mode M) to mode N and store in
+ operand 0 (which has mode N). Both modes must be fixed point.
+
+`extv'
+ Extract a bit-field from operand 1 (a register or memory operand),
+ where operand 2 specifies the width in bits and operand 3 the
+ starting bit, and store it in operand 0. Operand 0 must have mode
+ `word_mode'. Operand 1 may have mode `byte_mode' or `word_mode';
+ often `word_mode' is allowed only for registers. Operands 2 and 3
+ must be valid for `word_mode'.
+
+ The RTL generation pass generates this instruction only with
+ constants for operands 2 and 3.
+
+ The bit-field value is sign-extended to a full word integer before
+ it is stored in operand 0.
+
+`extzv'
+ Like `extv' except that the bit-field value is zero-extended.
+
+`insv'
+ Store operand 3 (which must be valid for `word_mode') into a
+ bit-field in operand 0, where operand 1 specifies the width in
+ bits and operand 2 the starting bit. Operand 0 may have mode
+ `byte_mode' or `word_mode'; often `word_mode' is allowed only for
+ registers. Operands 1 and 2 must be valid for `word_mode'.
+
+ The RTL generation pass generates this instruction only with
+ constants for operands 1 and 2.
+
+`movMODEcc'
+ Conditionally move operand 2 or operand 3 into operand 0 according
+ to the comparison in operand 1. If the comparison is true,
+ operand 2 is moved into operand 0, otherwise operand 3 is moved.
+
+ The mode of the operands being compared need not be the same as
+ the operands being moved. Some machines, sparc64 for example,
+ have instructions that conditionally move an integer value based
+ on the floating point condition codes and vice versa.
+
+ If the machine does not have conditional move instructions, do not
+ define these patterns.
+
+`sCOND'
+ Store zero or nonzero in the operand according to the condition
+ codes. Value stored is nonzero iff the condition COND is true.
+ COND is the name of a comparison operation expression code, such
+ as `eq', `lt' or `leu'.
+
+ You specify the mode that the operand must have when you write the
+ `match_operand' expression. The compiler automatically sees which
+ mode you have used and supplies an operand of that mode.
+
+ The value stored for a true condition must have 1 as its low bit,
+ or else must be negative. Otherwise the instruction is not
+ suitable and you should omit it from the machine description. You
+ describe to the compiler exactly which value is stored by defining
+ the macro `STORE_FLAG_VALUE' (*note Misc::). If a description
+ cannot be found that can be used for all the `sCOND' patterns, you
+ should omit those operations from the machine description.
+
+ These operations may fail, but should do so only in relatively
+ uncommon cases; if they would fail for common cases involving
+ integer comparisons, it is best to omit these patterns.
+
+ If these operations are omitted, the compiler will usually
+ generate code that copies the constant one to the target and
+ branches around an assignment of zero to the target. If this code
+ is more efficient than the potential instructions used for the
+ `sCOND' pattern followed by those required to convert the result
+ into a 1 or a zero in `SImode', you should omit the `sCOND'
+ operations from the machine description.
+
+`bCOND'
+ Conditional branch instruction. Operand 0 is a `label_ref' that
+ refers to the label to jump to. Jump if the condition codes meet
+ condition COND.
+
+ Some machines do not follow the model assumed here where a
+ comparison instruction is followed by a conditional branch
+ instruction. In that case, the `cmpM' (and `tstM') patterns should
+ simply store the operands away and generate all the required insns
+ in a `define_expand' (*note Expander Definitions::) for the
+ conditional branch operations. All calls to expand `bCOND'
+ patterns are immediately preceded by calls to expand either a
+ `cmpM' pattern or a `tstM' pattern.
+
+ Machines that use a pseudo register for the condition code value,
+ or where the mode used for the comparison depends on the condition
+ being tested, should also use the above mechanism. *Note Jump
+ Patterns::.
+
+ The above discussion also applies to the `movMODEcc' and `sCOND'
+ patterns.
+
+`jump'
+ A jump inside a function; an unconditional branch. Operand 0 is
+ the `label_ref' of the label to jump to. This pattern name is
+ mandatory on all machines.
+
+`call'
+ Subroutine call instruction returning no value. Operand 0 is the
+ function to call; operand 1 is the number of bytes of arguments
+ pushed as a `const_int'; operand 2 is the number of registers used
+ as operands.
+
+ On most machines, operand 2 is not actually stored into the RTL
+ pattern. It is supplied for the sake of some RISC machines which
+ need to put this information into the assembler code; they can put
+ it in the RTL instead of operand 1.
+
+ Operand 0 should be a `mem' RTX whose address is the address of the
+ function. Note, however, that this address can be a `symbol_ref'
+ expression even if it would not be a legitimate memory address on
+ the target machine. If it is also not a valid argument for a call
+ instruction, the pattern for this operation should be a
+ `define_expand' (*note Expander Definitions::) that places the
+ address into a register and uses that register in the call
+ instruction.
+
+`call_value'
+ Subroutine call instruction returning a value. Operand 0 is the
+ hard register in which the value is returned. There are three more
+ operands, the same as the three operands of the `call' instruction
+ (but with numbers increased by one).
+
+ Subroutines that return `BLKmode' objects use the `call' insn.
+
+`call_pop', `call_value_pop'
+ Similar to `call' and `call_value', except used if defined and if
+ `RETURN_POPS_ARGS' is nonzero. They should emit a `parallel' that
+ contains both the function call and a `set' to indicate the
+ adjustment made to the frame pointer.
+
+ For machines where `RETURN_POPS_ARGS' can be nonzero, the use of
+ these patterns increases the number of functions for which the
+ frame pointer can be eliminated, if desired.
+
+`untyped_call'
+ Subroutine call instruction returning a value of any type.
+ Operand 0 is the function to call; operand 1 is a memory location
+ where the result of calling the function is to be stored; operand
+ 2 is a `parallel' expression where each element is a `set'
+ expression that indicates the saving of a function return value
+ into the result block.
+
+ This instruction pattern should be defined to support
+ `__builtin_apply' on machines where special instructions are needed
+ to call a subroutine with arbitrary arguments or to save the value
+ returned. This instruction pattern is required on machines that
+ have multiple registers that can hold a return value (i.e.
+ `FUNCTION_VALUE_REGNO_P' is true for more than one register).
+
+`return'
+ Subroutine return instruction. This instruction pattern name
+ should be defined only if a single instruction can do all the work
+ of returning from a function.
+
+ Like the `movM' patterns, this pattern is also used after the RTL
+ generation phase. In this case it is to support machines where
+ multiple instructions are usually needed to return from a
+ function, but some class of functions only requires one
+ instruction to implement a return. Normally, the applicable
+ functions are those which do not need to save any registers or
+ allocate stack space.
+
+ For such machines, the condition specified in this pattern should
+ only be true when `reload_completed' is nonzero and the function's
+ epilogue would only be a single instruction. For machines with
+ register windows, the routine `leaf_function_p' may be used to
+ determine if a register window push is required.
+
+ Machines that have conditional return instructions should define
+ patterns such as
+
+ (define_insn ""
+ [(set (pc)
+ (if_then_else (match_operator
+ 0 "comparison_operator"
+ [(cc0) (const_int 0)])
+ (return)
+ (pc)))]
+ "CONDITION"
+ "...")
+
+ where CONDITION would normally be the same condition specified on
+ the named `return' pattern.
+
+`untyped_return'
+ Untyped subroutine return instruction. This instruction pattern
+ should be defined to support `__builtin_return' on machines where
+ special instructions are needed to return a value of any type.
+
+ Operand 0 is a memory location where the result of calling a
+ function with `__builtin_apply' is stored; operand 1 is a
+ `parallel' expression where each element is a `set' expression
+ that indicates the restoring of a function return value from the
+ result block.
+
+`nop'
+ No-op instruction. This instruction pattern name should always be
+ defined to output a no-op in assembler code. `(const_int 0)' will
+ do as an RTL pattern.
+
+`indirect_jump'
+ An instruction to jump to an address which is operand zero. This
+ pattern name is mandatory on all machines.
+
+`casesi'
+ Instruction to jump through a dispatch table, including bounds
+ checking. This instruction takes five operands:
+
+ 1. The index to dispatch on, which has mode `SImode'.
+
+ 2. The lower bound for indices in the table, an integer constant.
+
+ 3. The total range of indices in the table--the largest index
+ minus the smallest one (both inclusive).
+
+ 4. A label that precedes the table itself.
+
+ 5. A label to jump to if the index has a value outside the
+ bounds. (If the machine-description macro
+ `CASE_DROPS_THROUGH' is defined, then an out-of-bounds index
+ drops through to the code following the jump table instead of
+ jumping to this label. In that case, this label is not
+ actually used by the `casesi' instruction, but it is always
+ provided as an operand.)
+
+ The table is a `addr_vec' or `addr_diff_vec' inside of a
+ `jump_insn'. The number of elements in the table is one plus the
+ difference between the upper bound and the lower bound.
+
+`tablejump'
+ Instruction to jump to a variable address. This is a low-level
+ capability which can be used to implement a dispatch table when
+ there is no `casesi' pattern.
+
+ This pattern requires two operands: the address or offset, and a
+ label which should immediately precede the jump table. If the
+ macro `CASE_VECTOR_PC_RELATIVE' evaluates to a nonzero value then
+ the first operand is an offset which counts from the address of
+ the table; otherwise, it is an absolute address to jump to. In
+ either case, the first operand has mode `Pmode'.
+
+ The `tablejump' insn is always the last insn before the jump table
+ it uses. Its assembler code normally has no need to use the
+ second operand, but you should incorporate it in the RTL pattern so
+ that the jump optimizer will not delete the table as unreachable
+ code.
+
+`decrement_and_branch_until_zero'
+ Conditional branch instruction that decrements a register and
+ jumps if the register is nonzero. Operand 0 is the register to
+ decrement and test; operand 1 is the label to jump to if the
+ register is nonzero. *Note Looping Patterns::.
+
+ This optional instruction pattern is only used by the combiner,
+ typically for loops reversed by the loop optimizer when strength
+ reduction is enabled.
+
+`doloop_end'
+ Conditional branch instruction that decrements a register and
+ jumps if the register is nonzero. This instruction takes five
+ operands: Operand 0 is the register to decrement and test; operand
+ 1 is the number of loop iterations as a `const_int' or
+ `const0_rtx' if this cannot be determined until run-time; operand
+ 2 is the actual or estimated maximum number of iterations as a
+ `const_int'; operand 3 is the number of enclosed loops as a
+ `const_int' (an innermost loop has a value of 1); operand 4 is the
+ label to jump to if the register is nonzero. *Note Looping
+ Patterns::.
+
+ This optional instruction pattern should be defined for machines
+ with low-overhead looping instructions as the loop optimizer will
+ try to modify suitable loops to utilize it. If nested
+ low-overhead looping is not supported, use a `define_expand'
+ (*note Expander Definitions::) and make the pattern fail if
+ operand 3 is not `const1_rtx'. Similarly, if the actual or
+ estimated maximum number of iterations is too large for this
+ instruction, make it fail.
+
+`doloop_begin'
+ Companion instruction to `doloop_end' required for machines that
+ need to perform some initialization, such as loading special
+ registers used by a low-overhead looping instruction. If
+ initialization insns do not always need to be emitted, use a
+ `define_expand' (*note Expander Definitions::) and make it fail.
+
+`canonicalize_funcptr_for_compare'
+ Canonicalize the function pointer in operand 1 and store the result
+ into operand 0.
+
+ Operand 0 is always a `reg' and has mode `Pmode'; operand 1 may be
+ a `reg', `mem', `symbol_ref', `const_int', etc and also has mode
+ `Pmode'.
+
+ Canonicalization of a function pointer usually involves computing
+ the address of the function which would be called if the function
+ pointer were used in an indirect call.
+
+ Only define this pattern if function pointers on the target machine
+ can have different values but still call the same function when
+ used in an indirect call.
+
+`save_stack_block'
+`save_stack_function'
+`save_stack_nonlocal'
+`restore_stack_block'
+`restore_stack_function'
+`restore_stack_nonlocal'
+ Most machines save and restore the stack pointer by copying it to
+ or from an object of mode `Pmode'. Do not define these patterns on
+ such machines.
+
+ Some machines require special handling for stack pointer saves and
+ restores. On those machines, define the patterns corresponding to
+ the non-standard cases by using a `define_expand' (*note Expander
+ Definitions::) that produces the required insns. The three types
+ of saves and restores are:
+
+ 1. `save_stack_block' saves the stack pointer at the start of a
+ block that allocates a variable-sized object, and
+ `restore_stack_block' restores the stack pointer when the
+ block is exited.
+
+ 2. `save_stack_function' and `restore_stack_function' do a
+ similar job for the outermost block of a function and are
+ used when the function allocates variable-sized objects or
+ calls `alloca'. Only the epilogue uses the restored stack
+ pointer, allowing a simpler save or restore sequence on some
+ machines.
+
+ 3. `save_stack_nonlocal' is used in functions that contain labels
+ branched to by nested functions. It saves the stack pointer
+ in such a way that the inner function can use
+ `restore_stack_nonlocal' to restore the stack pointer. The
+ compiler generates code to restore the frame and argument
+ pointer registers, but some machines require saving and
+ restoring additional data such as register window information
+ or stack backchains. Place insns in these patterns to save
+ and restore any such required data.
+
+ When saving the stack pointer, operand 0 is the save area and
+ operand 1 is the stack pointer. The mode used to allocate the
+ save area defaults to `Pmode' but you can override that choice by
+ defining the `STACK_SAVEAREA_MODE' macro (*note Storage Layout::).
+ You must specify an integral mode, or `VOIDmode' if no save area
+ is needed for a particular type of save (either because no save is
+ needed or because a machine-specific save area can be used).
+ Operand 0 is the stack pointer and operand 1 is the save area for
+ restore operations. If `save_stack_block' is defined, operand 0
+ must not be `VOIDmode' since these saves can be arbitrarily nested.
+
+ A save area is a `mem' that is at a constant offset from
+ `virtual_stack_vars_rtx' when the stack pointer is saved for use by
+ nonlocal gotos and a `reg' in the other two cases.
+
+`allocate_stack'
+ Subtract (or add if `STACK_GROWS_DOWNWARD' is undefined) operand 1
+ from the stack pointer to create space for dynamically allocated
+ data.
+
+ Store the resultant pointer to this space into operand 0. If you
+ are allocating space from the main stack, do this by emitting a
+ move insn to copy `virtual_stack_dynamic_rtx' to operand 0. If
+ you are allocating the space elsewhere, generate code to copy the
+ location of the space to operand 0. In the latter case, you must
+ ensure this space gets freed when the corresponding space on the
+ main stack is free.
+
+ Do not define this pattern if all that must be done is the
+ subtraction. Some machines require other operations such as stack
+ probes or maintaining the back chain. Define this pattern to emit
+ those operations in addition to updating the stack pointer.
+
+`probe'
+ Some machines require instructions to be executed after space is
+ allocated from the stack, for example to generate a reference at
+ the bottom of the stack.
+
+ If you need to emit instructions before the stack has been
+ adjusted, put them into the `allocate_stack' pattern. Otherwise,
+ define this pattern to emit the required instructions.
+
+ No operands are provided.
+
+`check_stack'
+ If stack checking cannot be done on your system by probing the
+ stack with a load or store instruction (*note Stack Checking::),
+ define this pattern to perform the needed check and signaling an
+ error if the stack has overflowed. The single operand is the
+ location in the stack furthest from the current stack pointer that
+ you need to validate. Normally, on machines where this pattern is
+ needed, you would obtain the stack limit from a global or
+ thread-specific variable or register.
+
+`nonlocal_goto'
+ Emit code to generate a non-local goto, e.g., a jump from one
+ function to a label in an outer function. This pattern has four
+ arguments, each representing a value to be used in the jump. The
+ first argument is to be loaded into the frame pointer, the second
+ is the address to branch to (code to dispatch to the actual label),
+ the third is the address of a location where the stack is saved,
+ and the last is the address of the label, to be placed in the
+ location for the incoming static chain.
+
+ On most machines you need not define this pattern, since GCC will
+ already generate the correct code, which is to load the frame
+ pointer and static chain, restore the stack (using the
+ `restore_stack_nonlocal' pattern, if defined), and jump indirectly
+ to the dispatcher. You need only define this pattern if this code
+ will not work on your machine.
+
+`nonlocal_goto_receiver'
+ This pattern, if defined, contains code needed at the target of a
+ nonlocal goto after the code already generated by GCC. You will
+ not normally need to define this pattern. A typical reason why
+ you might need this pattern is if some value, such as a pointer to
+ a global table, must be restored when the frame pointer is
+ restored. Note that a nonlocal goto only occurs within a
+ unit-of-translation, so a global table pointer that is shared by
+ all functions of a given module need not be restored. There are
+ no arguments.
+
+`exception_receiver'
+ This pattern, if defined, contains code needed at the site of an
+ exception handler that isn't needed at the site of a nonlocal
+ goto. You will not normally need to define this pattern. A
+ typical reason why you might need this pattern is if some value,
+ such as a pointer to a global table, must be restored after
+ control flow is branched to the handler of an exception. There
+ are no arguments.
+
+`builtin_setjmp_setup'
+ This pattern, if defined, contains additional code needed to
+ initialize the `jmp_buf'. You will not normally need to define
+ this pattern. A typical reason why you might need this pattern is
+ if some value, such as a pointer to a global table, must be
+ restored. Though it is preferred that the pointer value be
+ recalculated if possible (given the address of a label for
+ instance). The single argument is a pointer to the `jmp_buf'.
+ Note that the buffer is five words long and that the first three
+ are normally used by the generic mechanism.
+
+`builtin_setjmp_receiver'
+ This pattern, if defined, contains code needed at the site of an
+ built-in setjmp that isn't needed at the site of a nonlocal goto.
+ You will not normally need to define this pattern. A typical
+ reason why you might need this pattern is if some value, such as a
+ pointer to a global table, must be restored. It takes one
+ argument, which is the label to which builtin_longjmp transfered
+ control; this pattern may be emitted at a small offset from that
+ label.
+
+`builtin_longjmp'
+ This pattern, if defined, performs the entire action of the
+ longjmp. You will not normally need to define this pattern unless
+ you also define `builtin_setjmp_setup'. The single argument is a
+ pointer to the `jmp_buf'.
+
+`eh_return'
+ This pattern, if defined, affects the way `__builtin_eh_return',
+ and thence the call frame exception handling library routines, are
+ built. It is intended to handle non-trivial actions needed along
+ the abnormal return path.
+
+ The pattern takes two arguments. The first is an offset to be
+ applied to the stack pointer. It will have been copied to some
+ appropriate location (typically `EH_RETURN_STACKADJ_RTX') which
+ will survive until after reload to when the normal epilogue is
+ generated. The second argument is the address of the exception
+ handler to which the function should return. This will normally
+ need to copied by the pattern to some special register or memory
+ location.
+
+ This pattern only needs to be defined if call frame exception
+ handling is to be used, and simple moves involving
+ `EH_RETURN_STACKADJ_RTX' and `EH_RETURN_HANDLER_RTX' are not
+ sufficient.
+
+`prologue'
+ This pattern, if defined, emits RTL for entry to a function. The
+ function entry is responsible for setting up the stack frame,
+ initializing the frame pointer register, saving callee saved
+ registers, etc.
+
+ Using a prologue pattern is generally preferred over defining
+ `TARGET_ASM_FUNCTION_PROLOGUE' to emit assembly code for the
+ prologue.
+
+ The `prologue' pattern is particularly useful for targets which
+ perform instruction scheduling.
+
+`epilogue'
+ This pattern emits RTL for exit from a function. The function
+ exit is responsible for deallocating the stack frame, restoring
+ callee saved registers and emitting the return instruction.
+
+ Using an epilogue pattern is generally preferred over defining
+ `TARGET_ASM_FUNCTION_EPILOGUE' to emit assembly code for the
+ epilogue.
+
+ The `epilogue' pattern is particularly useful for targets which
+ perform instruction scheduling or which have delay slots for their
+ return instruction.
+
+`sibcall_epilogue'
+ This pattern, if defined, emits RTL for exit from a function
+ without the final branch back to the calling function. This
+ pattern will be emitted before any sibling call (aka tail call)
+ sites.
+
+ The `sibcall_epilogue' pattern must not clobber any arguments used
+ for parameter passing or any stack slots for arguments passed to
+ the current function.
+
+`trap'
+ This pattern, if defined, signals an error, typically by causing
+ some kind of signal to be raised. Among other places, it is used
+ by the Java front end to signal `invalid array index' exceptions.
+
+`conditional_trap'
+ Conditional trap instruction. Operand 0 is a piece of RTL which
+ performs a comparison. Operand 1 is the trap code, an integer.
+
+ A typical `conditional_trap' pattern looks like
+
+ (define_insn "conditional_trap"
+ [(trap_if (match_operator 0 "trap_operator"
+ [(cc0) (const_int 0)])
+ (match_operand 1 "const_int_operand" "i"))]
+ ""
+ "...")
+
+`prefetch'
+ This pattern, if defined, emits code for a non-faulting data
+ prefetch instruction. Operand 0 is the address of the memory to
+ prefetch. Operand 1 is a constant 1 if the prefetch is preparing
+ for a write to the memory address, or a constant 0 otherwise.
+ Operand 2 is the expected degree of temporal locality of the data
+ and is a value between 0 and 3, inclusive; 0 means that the data
+ has no temporal locality, so it need not be left in the cache
+ after the access; 3 means that the data has a high degree of
+ temporal locality and should be left in all levels of cache
+ possible; 1 and 2 mean, respectively, a low or moderate degree of
+ temporal locality.
+
+ Targets that do not support write prefetches or locality hints can
+ ignore the values of operands 1 and 2.
+
+`cycle_display'
+ This pattern, if present, will be emitted by the instruction
+ scheduler at the beginning of each new clock cycle. This can be
+ used for annotating the assembler output with cycle counts.
+ Operand 0 is a `const_int' that holds the clock cycle.
+
+
+\1f
+File: gccint.info, Node: Pattern Ordering, Next: Dependent Patterns, Prev: Standard Names, Up: Machine Desc
+
+9.9 When the Order of Patterns Matters
+======================================
+
+Sometimes an insn can match more than one instruction pattern. Then the
+pattern that appears first in the machine description is the one used.
+Therefore, more specific patterns (patterns that will match fewer
+things) and faster instructions (those that will produce better code
+when they do match) should usually go first in the description.
+
+ In some cases the effect of ordering the patterns can be used to hide
+a pattern when it is not valid. For example, the 68000 has an
+instruction for converting a fullword to floating point and another for
+converting a byte to floating point. An instruction converting an
+integer to floating point could match either one. We put the pattern
+to convert the fullword first to make sure that one will be used rather
+than the other. (Otherwise a large integer might be generated as a
+single-byte immediate quantity, which would not work.) Instead of
+using this pattern ordering it would be possible to make the pattern
+for convert-a-byte smart enough to deal properly with any constant
+value.
+
+\1f
+File: gccint.info, Node: Dependent Patterns, Next: Jump Patterns, Prev: Pattern Ordering, Up: Machine Desc
+
+9.10 Interdependence of Patterns
+================================
+
+Every machine description must have a named pattern for each of the
+conditional branch names `bCOND'. The recognition template must always
+have the form
+
+ (set (pc)
+ (if_then_else (COND (cc0) (const_int 0))
+ (label_ref (match_operand 0 "" ""))
+ (pc)))
+
+In addition, every machine description must have an anonymous pattern
+for each of the possible reverse-conditional branches. Their templates
+look like
+
+ (set (pc)
+ (if_then_else (COND (cc0) (const_int 0))
+ (pc)
+ (label_ref (match_operand 0 "" ""))))
+
+They are necessary because jump optimization can turn direct-conditional
+branches into reverse-conditional branches.
+
+ It is often convenient to use the `match_operator' construct to
+reduce the number of patterns that must be specified for branches. For
+example,
+
+ (define_insn ""
+ [(set (pc)
+ (if_then_else (match_operator 0 "comparison_operator"
+ [(cc0) (const_int 0)])
+ (pc)
+ (label_ref (match_operand 1 "" ""))))]
+ "CONDITION"
+ "...")
+
+ In some cases machines support instructions identical except for the
+machine mode of one or more operands. For example, there may be
+"sign-extend halfword" and "sign-extend byte" instructions whose
+patterns are
+
+ (set (match_operand:SI 0 ...)
+ (extend:SI (match_operand:HI 1 ...)))
+
+ (set (match_operand:SI 0 ...)
+ (extend:SI (match_operand:QI 1 ...)))
+
+Constant integers do not specify a machine mode, so an instruction to
+extend a constant value could match either pattern. The pattern it
+actually will match is the one that appears first in the file. For
+correct results, this must be the one for the widest possible mode
+(`HImode', here). If the pattern matches the `QImode' instruction, the
+results will be incorrect if the constant value does not actually fit
+that mode.
+
+ Such instructions to extend constants are rarely generated because
+they are optimized away, but they do occasionally happen in nonoptimized
+compilations.
+
+ If a constraint in a pattern allows a constant, the reload pass may
+replace a register with a constant permitted by the constraint in some
+cases. Similarly for memory references. Because of this substitution,
+you should not provide separate patterns for increment and decrement
+instructions. Instead, they should be generated from the same pattern
+that supports register-register add insns by examining the operands and
+generating the appropriate machine instruction.
+
+\1f
+File: gccint.info, Node: Jump Patterns, Next: Looping Patterns, Prev: Dependent Patterns, Up: Machine Desc
+
+9.11 Defining Jump Instruction Patterns
+=======================================
+
+For most machines, GCC assumes that the machine has a condition code.
+A comparison insn sets the condition code, recording the results of both
+signed and unsigned comparison of the given operands. A separate branch
+insn tests the condition code and branches or not according its value.
+The branch insns come in distinct signed and unsigned flavors. Many
+common machines, such as the VAX, the 68000 and the 32000, work this
+way.
+
+ Some machines have distinct signed and unsigned compare
+instructions, and only one set of conditional branch instructions. The
+easiest way to handle these machines is to treat them just like the
+others until the final stage where assembly code is written. At this
+time, when outputting code for the compare instruction, peek ahead at
+the following branch using `next_cc0_user (insn)'. (The variable
+`insn' refers to the insn being output, in the output-writing code in
+an instruction pattern.) If the RTL says that is an unsigned branch,
+output an unsigned compare; otherwise output a signed compare. When
+the branch itself is output, you can treat signed and unsigned branches
+identically.
+
+ The reason you can do this is that GCC always generates a pair of
+consecutive RTL insns, possibly separated by `note' insns, one to set
+the condition code and one to test it, and keeps the pair inviolate
+until the end.
+
+ To go with this technique, you must define the machine-description
+macro `NOTICE_UPDATE_CC' to do `CC_STATUS_INIT'; in other words, no
+compare instruction is superfluous.
+
+ Some machines have compare-and-branch instructions and no condition
+code. A similar technique works for them. When it is time to "output"
+a compare instruction, record its operands in two static variables.
+When outputting the branch-on-condition-code instruction that follows,
+actually output a compare-and-branch instruction that uses the
+remembered operands.
+
+ It also works to define patterns for compare-and-branch instructions.
+In optimizing compilation, the pair of compare and branch instructions
+will be combined according to these patterns. But this does not happen
+if optimization is not requested. So you must use one of the solutions
+above in addition to any special patterns you define.
+
+ In many RISC machines, most instructions do not affect the condition
+code and there may not even be a separate condition code register. On
+these machines, the restriction that the definition and use of the
+condition code be adjacent insns is not necessary and can prevent
+important optimizations. For example, on the IBM RS/6000, there is a
+delay for taken branches unless the condition code register is set three
+instructions earlier than the conditional branch. The instruction
+scheduler cannot perform this optimization if it is not permitted to
+separate the definition and use of the condition code register.
+
+ On these machines, do not use `(cc0)', but instead use a register to
+represent the condition code. If there is a specific condition code
+register in the machine, use a hard register. If the condition code or
+comparison result can be placed in any general register, or if there are
+multiple condition registers, use a pseudo register.
+
+ On some machines, the type of branch instruction generated may
+depend on the way the condition code was produced; for example, on the
+68k and Sparc, setting the condition code directly from an add or
+subtract instruction does not clear the overflow bit the way that a test
+instruction does, so a different branch instruction must be used for
+some conditional branches. For machines that use `(cc0)', the set and
+use of the condition code must be adjacent (separated only by `note'
+insns) allowing flags in `cc_status' to be used. (*Note Condition
+Code::.) Also, the comparison and branch insns can be located from
+each other by using the functions `prev_cc0_setter' and `next_cc0_user'.
+
+ However, this is not true on machines that do not use `(cc0)'. On
+those machines, no assumptions can be made about the adjacency of the
+compare and branch insns and the above methods cannot be used. Instead,
+we use the machine mode of the condition code register to record
+different formats of the condition code register.
+
+ Registers used to store the condition code value should have a mode
+that is in class `MODE_CC'. Normally, it will be `CCmode'. If
+additional modes are required (as for the add example mentioned above in
+the Sparc), define the macro `EXTRA_CC_MODES' to list the additional
+modes required (*note Condition Code::). Also define `SELECT_CC_MODE'
+to choose a mode given an operand of a compare.
+
+ If it is known during RTL generation that a different mode will be
+required (for example, if the machine has separate compare instructions
+for signed and unsigned quantities, like most IBM processors), they can
+be specified at that time.
+
+ If the cases that require different modes would be made by
+instruction combination, the macro `SELECT_CC_MODE' determines which
+machine mode should be used for the comparison result. The patterns
+should be written using that mode. To support the case of the add on
+the Sparc discussed above, we have the pattern
+
+ (define_insn ""
+ [(set (reg:CC_NOOV 0)
+ (compare:CC_NOOV
+ (plus:SI (match_operand:SI 0 "register_operand" "%r")
+ (match_operand:SI 1 "arith_operand" "rI"))
+ (const_int 0)))]
+ ""
+ "...")
+
+ The `SELECT_CC_MODE' macro on the Sparc returns `CC_NOOVmode' for
+comparisons whose argument is a `plus'.
+
+\1f
+File: gccint.info, Node: Looping Patterns, Next: Insn Canonicalizations, Prev: Jump Patterns, Up: Machine Desc
+
+9.12 Defining Looping Instruction Patterns
+==========================================
+
+Some machines have special jump instructions that can be utilised to
+make loops more efficient. A common example is the 68000 `dbra'
+instruction which performs a decrement of a register and a branch if the
+result was greater than zero. Other machines, in particular digital
+signal processors (DSPs), have special block repeat instructions to
+provide low-overhead loop support. For example, the TI TMS320C3x/C4x
+DSPs have a block repeat instruction that loads special registers to
+mark the top and end of a loop and to count the number of loop
+iterations. This avoids the need for fetching and executing a
+`dbra'-like instruction and avoids pipeline stalls associated with the
+jump.
+
+ GCC has three special named patterns to support low overhead looping.
+They are `decrement_and_branch_until_zero', `doloop_begin', and
+`doloop_end'. The first pattern, `decrement_and_branch_until_zero', is
+not emitted during RTL generation but may be emitted during the
+instruction combination phase. This requires the assistance of the
+loop optimizer, using information collected during strength reduction,
+to reverse a loop to count down to zero. Some targets also require the
+loop optimizer to add a `REG_NONNEG' note to indicate that the
+iteration count is always positive. This is needed if the target
+performs a signed loop termination test. For example, the 68000 uses a
+pattern similar to the following for its `dbra' instruction:
+
+ (define_insn "decrement_and_branch_until_zero"
+ [(set (pc)
+ (if_then_else
+ (ge (plus:SI (match_operand:SI 0 "general_operand" "+d*am")
+ (const_int -1))
+ (const_int 0))
+ (label_ref (match_operand 1 "" ""))
+ (pc)))
+ (set (match_dup 0)
+ (plus:SI (match_dup 0)
+ (const_int -1)))]
+ "find_reg_note (insn, REG_NONNEG, 0)"
+ "...")
+
+ Note that since the insn is both a jump insn and has an output, it
+must deal with its own reloads, hence the `m' constraints. Also note
+that since this insn is generated by the instruction combination phase
+combining two sequential insns together into an implicit parallel insn,
+the iteration counter needs to be biased by the same amount as the
+decrement operation, in this case -1. Note that the following similar
+pattern will not be matched by the combiner.
+
+ (define_insn "decrement_and_branch_until_zero"
+ [(set (pc)
+ (if_then_else
+ (ge (match_operand:SI 0 "general_operand" "+d*am")
+ (const_int 1))
+ (label_ref (match_operand 1 "" ""))
+ (pc)))
+ (set (match_dup 0)
+ (plus:SI (match_dup 0)
+ (const_int -1)))]
+ "find_reg_note (insn, REG_NONNEG, 0)"
+ "...")
+
+ The other two special looping patterns, `doloop_begin' and
+`doloop_end', are emitted by the loop optimizer for certain
+well-behaved loops with a finite number of loop iterations using
+information collected during strength reduction.
+
+ The `doloop_end' pattern describes the actual looping instruction
+(or the implicit looping operation) and the `doloop_begin' pattern is
+an optional companion pattern that can be used for initialization
+needed for some low-overhead looping instructions.
+
+ Note that some machines require the actual looping instruction to be
+emitted at the top of the loop (e.g., the TMS320C3x/C4x DSPs). Emitting
+the true RTL for a looping instruction at the top of the loop can cause
+problems with flow analysis. So instead, a dummy `doloop' insn is
+emitted at the end of the loop. The machine dependent reorg pass checks
+for the presence of this `doloop' insn and then searches back to the
+top of the loop, where it inserts the true looping insn (provided there
+are no instructions in the loop which would cause problems). Any
+additional labels can be emitted at this point. In addition, if the
+desired special iteration counter register was not allocated, this
+machine dependent reorg pass could emit a traditional compare and jump
+instruction pair.
+
+ The essential difference between the
+`decrement_and_branch_until_zero' and the `doloop_end' patterns is that
+the loop optimizer allocates an additional pseudo register for the
+latter as an iteration counter. This pseudo register cannot be used
+within the loop (i.e., general induction variables cannot be derived
+from it), however, in many cases the loop induction variable may become
+redundant and removed by the flow pass.
\1f
-File: gccint.info, Node: Test Suites, Prev: gcc Directory, Up: Source Tree
+File: gccint.info, Node: Insn Canonicalizations, Next: Expander Definitions, Prev: Looping Patterns, Up: Machine Desc
+
+9.13 Canonicalization of Instructions
+=====================================
+
+There are often cases where multiple RTL expressions could represent an
+operation performed by a single machine instruction. This situation is
+most commonly encountered with logical, branch, and multiply-accumulate
+instructions. In such cases, the compiler attempts to convert these
+multiple RTL expressions into a single canonical form to reduce the
+number of insn patterns required.
+
+ In addition to algebraic simplifications, following canonicalizations
+are performed:
+
+ * For commutative and comparison operators, a constant is always
+ made the second operand. If a machine only supports a constant as
+ the second operand, only patterns that match a constant in the
+ second operand need be supplied.
+
+ For these operators, if only one operand is a `neg', `not',
+ `mult', `plus', or `minus' expression, it will be the first
+ operand.
+
+ * For the `compare' operator, a constant is always the second operand
+ on machines where `cc0' is used (*note Jump Patterns::). On other
+ machines, there are rare cases where the compiler might want to
+ construct a `compare' with a constant as the first operand.
+ However, these cases are not common enough for it to be worthwhile
+ to provide a pattern matching a constant as the first operand
+ unless the machine actually has such an instruction.
+
+ An operand of `neg', `not', `mult', `plus', or `minus' is made the
+ first operand under the same conditions as above.
+
+ * `(minus X (const_int N))' is converted to `(plus X (const_int
+ -N))'.
+
+ * Within address computations (i.e., inside `mem'), a left shift is
+ converted into the appropriate multiplication by a power of two.
+
+ * De`Morgan's Law is used to move bitwise negation inside a bitwise
+ logical-and or logical-or operation. If this results in only one
+ operand being a `not' expression, it will be the first one.
+
+ A machine that has an instruction that performs a bitwise
+ logical-and of one operand with the bitwise negation of the other
+ should specify the pattern for that instruction as
+
+ (define_insn ""
+ [(set (match_operand:M 0 ...)
+ (and:M (not:M (match_operand:M 1 ...))
+ (match_operand:M 2 ...)))]
+ "..."
+ "...")
+
+ Similarly, a pattern for a "NAND" instruction should be written
+
+ (define_insn ""
+ [(set (match_operand:M 0 ...)
+ (ior:M (not:M (match_operand:M 1 ...))
+ (not:M (match_operand:M 2 ...))))]
+ "..."
+ "...")
+
+ In both cases, it is not necessary to include patterns for the many
+ logically equivalent RTL expressions.
+
+ * The only possible RTL expressions involving both bitwise
+ exclusive-or and bitwise negation are `(xor:M X Y)' and `(not:M
+ (xor:M X Y))'.
+
+ * The sum of three items, one of which is a constant, will only
+ appear in the form
+
+ (plus:M (plus:M X Y) CONSTANT)
+
+ * On machines that do not use `cc0', `(compare X (const_int 0))'
+ will be converted to X.
+
+ * Equality comparisons of a group of bits (usually a single bit)
+ with zero will be written using `zero_extract' rather than the
+ equivalent `and' or `sign_extract' operations.
+
+
+\1f
+File: gccint.info, Node: Expander Definitions, Next: Insn Splitting, Prev: Insn Canonicalizations, Up: Machine Desc
+
+9.14 Defining RTL Sequences for Code Generation
+===============================================
+
+On some target machines, some standard pattern names for RTL generation
+cannot be handled with single insn, but a sequence of RTL insns can
+represent them. For these target machines, you can write a
+`define_expand' to specify how to generate the sequence of RTL.
+
+ A `define_expand' is an RTL expression that looks almost like a
+`define_insn'; but, unlike the latter, a `define_expand' is used only
+for RTL generation and it can produce more than one RTL insn.
+
+ A `define_expand' RTX has four operands:
+
+ * The name. Each `define_expand' must have a name, since the only
+ use for it is to refer to it by name.
+
+ * The RTL template. This is a vector of RTL expressions representing
+ a sequence of separate instructions. Unlike `define_insn', there
+ is no implicit surrounding `PARALLEL'.
+
+ * The condition, a string containing a C expression. This
+ expression is used to express how the availability of this pattern
+ depends on subclasses of target machine, selected by command-line
+ options when GCC is run. This is just like the condition of a
+ `define_insn' that has a standard name. Therefore, the condition
+ (if present) may not depend on the data in the insn being matched,
+ but only the target-machine-type flags. The compiler needs to
+ test these conditions during initialization in order to learn
+ exactly which named instructions are available in a particular run.
+
+ * The preparation statements, a string containing zero or more C
+ statements which are to be executed before RTL code is generated
+ from the RTL template.
+
+ Usually these statements prepare temporary registers for use as
+ internal operands in the RTL template, but they can also generate
+ RTL insns directly by calling routines such as `emit_insn', etc.
+ Any such insns precede the ones that come from the RTL template.
+
+ Every RTL insn emitted by a `define_expand' must match some
+`define_insn' in the machine description. Otherwise, the compiler will
+crash when trying to generate code for the insn or trying to optimize
+it.
+
+ The RTL template, in addition to controlling generation of RTL insns,
+also describes the operands that need to be specified when this pattern
+is used. In particular, it gives a predicate for each operand.
+
+ A true operand, which needs to be specified in order to generate RTL
+from the pattern, should be described with a `match_operand' in its
+first occurrence in the RTL template. This enters information on the
+operand's predicate into the tables that record such things. GCC uses
+the information to preload the operand into a register if that is
+required for valid RTL code. If the operand is referred to more than
+once, subsequent references should use `match_dup'.
+
+ The RTL template may also refer to internal "operands" which are
+temporary registers or labels used only within the sequence made by the
+`define_expand'. Internal operands are substituted into the RTL
+template with `match_dup', never with `match_operand'. The values of
+the internal operands are not passed in as arguments by the compiler
+when it requests use of this pattern. Instead, they are computed
+within the pattern, in the preparation statements. These statements
+compute the values and store them into the appropriate elements of
+`operands' so that `match_dup' can find them.
+
+ There are two special macros defined for use in the preparation
+statements: `DONE' and `FAIL'. Use them with a following semicolon, as
+a statement.
+
+`DONE'
+ Use the `DONE' macro to end RTL generation for the pattern. The
+ only RTL insns resulting from the pattern on this occasion will be
+ those already emitted by explicit calls to `emit_insn' within the
+ preparation statements; the RTL template will not be generated.
+
+`FAIL'
+ Make the pattern fail on this occasion. When a pattern fails, it
+ means that the pattern was not truly available. The calling
+ routines in the compiler will try other strategies for code
+ generation using other patterns.
+
+ Failure is currently supported only for binary (addition,
+ multiplication, shifting, etc.) and bit-field (`extv', `extzv',
+ and `insv') operations.
+
+ If the preparation falls through (invokes neither `DONE' nor
+`FAIL'), then the `define_expand' acts like a `define_insn' in that the
+RTL template is used to generate the insn.
+
+ The RTL template is not used for matching, only for generating the
+initial insn list. If the preparation statement always invokes `DONE'
+or `FAIL', the RTL template may be reduced to a simple list of
+operands, such as this example:
+
+ (define_expand "addsi3"
+ [(match_operand:SI 0 "register_operand" "")
+ (match_operand:SI 1 "register_operand" "")
+ (match_operand:SI 2 "register_operand" "")]
+ ""
+ "
+ {
+ handle_add (operands[0], operands[1], operands[2]);
+ DONE;
+ }")
+
+ Here is an example, the definition of left-shift for the SPUR chip:
+
+ (define_expand "ashlsi3"
+ [(set (match_operand:SI 0 "register_operand" "")
+ (ashift:SI
+ (match_operand:SI 1 "register_operand" "")
+ (match_operand:SI 2 "nonmemory_operand" "")))]
+ ""
+ "
+
+ {
+ if (GET_CODE (operands[2]) != CONST_INT
+ || (unsigned) INTVAL (operands[2]) > 3)
+ FAIL;
+ }")
+
+This example uses `define_expand' so that it can generate an RTL insn
+for shifting when the shift-count is in the supported range of 0 to 3
+but fail in other cases where machine insns aren't available. When it
+fails, the compiler tries another strategy using different patterns
+(such as, a library call).
+
+ If the compiler were able to handle nontrivial condition-strings in
+patterns with names, then it would be possible to use a `define_insn'
+in that case. Here is another case (zero-extension on the 68000) which
+makes more use of the power of `define_expand':
+
+ (define_expand "zero_extendhisi2"
+ [(set (match_operand:SI 0 "general_operand" "")
+ (const_int 0))
+ (set (strict_low_part
+ (subreg:HI
+ (match_dup 0)
+ 0))
+ (match_operand:HI 1 "general_operand" ""))]
+ ""
+ "operands[1] = make_safe_from (operands[1], operands[0]);")
+
+Here two RTL insns are generated, one to clear the entire output operand
+and the other to copy the input operand into its low half. This
+sequence is incorrect if the input operand refers to [the old value of]
+the output operand, so the preparation statement makes sure this isn't
+so. The function `make_safe_from' copies the `operands[1]' into a
+temporary register if it refers to `operands[0]'. It does this by
+emitting another RTL insn.
+
+ Finally, a third example shows the use of an internal operand.
+Zero-extension on the SPUR chip is done by `and'-ing the result against
+a halfword mask. But this mask cannot be represented by a `const_int'
+because the constant value is too large to be legitimate on this
+machine. So it must be copied into a register with `force_reg' and
+then the register used in the `and'.
+
+ (define_expand "zero_extendhisi2"
+ [(set (match_operand:SI 0 "register_operand" "")
+ (and:SI (subreg:SI
+ (match_operand:HI 1 "register_operand" "")
+ 0)
+ (match_dup 2)))]
+ ""
+ "operands[2]
+ = force_reg (SImode, GEN_INT (65535)); ")
+
+ *Note_* If the `define_expand' is used to serve a standard binary or
+unary arithmetic operation or a bit-field operation, then the last insn
+it generates must not be a `code_label', `barrier' or `note'. It must
+be an `insn', `jump_insn' or `call_insn'. If you don't need a real insn
+at the end, emit an insn to copy the result of the operation into
+itself. Such an insn will generate no code, but it can avoid problems
+in the compiler.
+
+\1f
+File: gccint.info, Node: Insn Splitting, Next: Including Patterns, Prev: Expander Definitions, Up: Machine Desc
+
+9.15 Defining How to Split Instructions
+=======================================
+
+There are two cases where you should specify how to split a pattern into
+multiple insns. On machines that have instructions requiring delay
+slots (*note Delay Slots::) or that have instructions whose output is
+not available for multiple cycles (*note Function Units::), the compiler
+phases that optimize these cases need to be able to move insns into
+one-instruction delay slots. However, some insns may generate more
+than one machine instruction. These insns cannot be placed into a
+delay slot.
+
+ Often you can rewrite the single insn as a list of individual insns,
+each corresponding to one machine instruction. The disadvantage of
+doing so is that it will cause the compilation to be slower and require
+more space. If the resulting insns are too complex, it may also
+suppress some optimizations. The compiler splits the insn if there is a
+reason to believe that it might improve instruction or delay slot
+scheduling.
+
+ The insn combiner phase also splits putative insns. If three insns
+are merged into one insn with a complex expression that cannot be
+matched by some `define_insn' pattern, the combiner phase attempts to
+split the complex pattern into two insns that are recognized. Usually
+it can break the complex pattern into two patterns by splitting out some
+subexpression. However, in some other cases, such as performing an
+addition of a large constant in two insns on a RISC machine, the way to
+split the addition into two insns is machine-dependent.
+
+ The `define_split' definition tells the compiler how to split a
+complex insn into several simpler insns. It looks like this:
+
+ (define_split
+ [INSN-PATTERN]
+ "CONDITION"
+ [NEW-INSN-PATTERN-1
+ NEW-INSN-PATTERN-2
+ ...]
+ "PREPARATION-STATEMENTS")
+
+ INSN-PATTERN is a pattern that needs to be split and CONDITION is
+the final condition to be tested, as in a `define_insn'. When an insn
+matching INSN-PATTERN and satisfying CONDITION is found, it is replaced
+in the insn list with the insns given by NEW-INSN-PATTERN-1,
+NEW-INSN-PATTERN-2, etc.
+
+ The PREPARATION-STATEMENTS are similar to those statements that are
+specified for `define_expand' (*note Expander Definitions::) and are
+executed before the new RTL is generated to prepare for the generated
+code or emit some insns whose pattern is not fixed. Unlike those in
+`define_expand', however, these statements must not generate any new
+pseudo-registers. Once reload has completed, they also must not
+allocate any space in the stack frame.
+
+ Patterns are matched against INSN-PATTERN in two different
+circumstances. If an insn needs to be split for delay slot scheduling
+or insn scheduling, the insn is already known to be valid, which means
+that it must have been matched by some `define_insn' and, if
+`reload_completed' is nonzero, is known to satisfy the constraints of
+that `define_insn'. In that case, the new insn patterns must also be
+insns that are matched by some `define_insn' and, if `reload_completed'
+is nonzero, must also satisfy the constraints of those definitions.
+
+ As an example of this usage of `define_split', consider the following
+example from `a29k.md', which splits a `sign_extend' from `HImode' to
+`SImode' into a pair of shift insns:
+
+ (define_split
+ [(set (match_operand:SI 0 "gen_reg_operand" "")
+ (sign_extend:SI (match_operand:HI 1 "gen_reg_operand" "")))]
+ ""
+ [(set (match_dup 0)
+ (ashift:SI (match_dup 1)
+ (const_int 16)))
+ (set (match_dup 0)
+ (ashiftrt:SI (match_dup 0)
+ (const_int 16)))]
+ "
+ { operands[1] = gen_lowpart (SImode, operands[1]); }")
+
+ When the combiner phase tries to split an insn pattern, it is always
+the case that the pattern is _not_ matched by any `define_insn'. The
+combiner pass first tries to split a single `set' expression and then
+the same `set' expression inside a `parallel', but followed by a
+`clobber' of a pseudo-reg to use as a scratch register. In these
+cases, the combiner expects exactly two new insn patterns to be
+generated. It will verify that these patterns match some `define_insn'
+definitions, so you need not do this test in the `define_split' (of
+course, there is no point in writing a `define_split' that will never
+produce insns that match).
+
+ Here is an example of this use of `define_split', taken from
+`rs6000.md':
+
+ (define_split
+ [(set (match_operand:SI 0 "gen_reg_operand" "")
+ (plus:SI (match_operand:SI 1 "gen_reg_operand" "")
+ (match_operand:SI 2 "non_add_cint_operand" "")))]
+ ""
+ [(set (match_dup 0) (plus:SI (match_dup 1) (match_dup 3)))
+ (set (match_dup 0) (plus:SI (match_dup 0) (match_dup 4)))]
+ "
+ {
+ int low = INTVAL (operands[2]) & 0xffff;
+ int high = (unsigned) INTVAL (operands[2]) >> 16;
+
+ if (low & 0x8000)
+ high++, low |= 0xffff0000;
+
+ operands[3] = GEN_INT (high << 16);
+ operands[4] = GEN_INT (low);
+ }")
+
+ Here the predicate `non_add_cint_operand' matches any `const_int'
+that is _not_ a valid operand of a single add insn. The add with the
+smaller displacement is written so that it can be substituted into the
+address of a subsequent operation.
+
+ An example that uses a scratch register, from the same file,
+generates an equality comparison of a register and a large constant:
+
+ (define_split
+ [(set (match_operand:CC 0 "cc_reg_operand" "")
+ (compare:CC (match_operand:SI 1 "gen_reg_operand" "")
+ (match_operand:SI 2 "non_short_cint_operand" "")))
+ (clobber (match_operand:SI 3 "gen_reg_operand" ""))]
+ "find_single_use (operands[0], insn, 0)
+ && (GET_CODE (*find_single_use (operands[0], insn, 0)) == EQ
+ || GET_CODE (*find_single_use (operands[0], insn, 0)) == NE)"
+ [(set (match_dup 3) (xor:SI (match_dup 1) (match_dup 4)))
+ (set (match_dup 0) (compare:CC (match_dup 3) (match_dup 5)))]
+ "
+ {
+ /* Get the constant we are comparing against, C, and see what it
+ looks like sign-extended to 16 bits. Then see what constant
+ could be XOR'ed with C to get the sign-extended value. */
+
+ int c = INTVAL (operands[2]);
+ int sextc = (c << 16) >> 16;
+ int xorv = c ^ sextc;
+
+ operands[4] = GEN_INT (xorv);
+ operands[5] = GEN_INT (sextc);
+ }")
+
+ To avoid confusion, don't write a single `define_split' that accepts
+some insns that match some `define_insn' as well as some insns that
+don't. Instead, write two separate `define_split' definitions, one for
+the insns that are valid and one for the insns that are not valid.
+
+ The splitter is allowed to split jump instructions into sequence of
+jumps or create new jumps in while splitting non-jump instructions. As
+the central flowgraph and branch prediction information needs to be
+updated, several restriction apply.
+
+ Splitting of jump instruction into sequence that over by another jump
+instruction is always valid, as compiler expect identical behavior of
+new jump. When new sequence contains multiple jump instructions or new
+labels, more assistance is needed. Splitter is required to create only
+unconditional jumps, or simple conditional jump instructions.
+Additionally it must attach a `REG_BR_PROB' note to each conditional
+jump. An global variable `split_branch_probability' hold the
+probability of original branch in case it was an simple conditional
+jump, -1 otherwise. To simplify recomputing of edge frequencies, new
+sequence is required to have only forward jumps to the newly created
+labels.
+
+ For the common case where the pattern of a define_split exactly
+matches the pattern of a define_insn, use `define_insn_and_split'. It
+looks like this:
+
+ (define_insn_and_split
+ [INSN-PATTERN]
+ "CONDITION"
+ "OUTPUT-TEMPLATE"
+ "SPLIT-CONDITION"
+ [NEW-INSN-PATTERN-1
+ NEW-INSN-PATTERN-2
+ ...]
+ "PREPARATION-STATEMENTS"
+ [INSN-ATTRIBUTES])
+
+ INSN-PATTERN, CONDITION, OUTPUT-TEMPLATE, and INSN-ATTRIBUTES are
+used as in `define_insn'. The NEW-INSN-PATTERN vector and the
+PREPARATION-STATEMENTS are used as in a `define_split'. The
+SPLIT-CONDITION is also used as in `define_split', with the additional
+behavior that if the condition starts with `&&', the condition used for
+the split will be the constructed as a logical "and" of the split
+condition with the insn condition. For example, from i386.md:
+
+ (define_insn_and_split "zero_extendhisi2_and"
+ [(set (match_operand:SI 0 "register_operand" "=r")
+ (zero_extend:SI (match_operand:HI 1 "register_operand" "0")))
+ (clobber (reg:CC 17))]
+ "TARGET_ZERO_EXTEND_WITH_AND && !optimize_size"
+ "#"
+ "&& reload_completed"
+ [(parallel [(set (match_dup 0)
+ (and:SI (match_dup 0) (const_int 65535)))
+ (clobber (reg:CC 17))])]
+ ""
+ [(set_attr "type" "alu1")])
+
+ In this case, the actual split condition will be
+`TARGET_ZERO_EXTEND_WITH_AND && !optimize_size && reload_completed'.
+
+ The `define_insn_and_split' construction provides exactly the same
+functionality as two separate `define_insn' and `define_split'
+patterns. It exists for compactness, and as a maintenance tool to
+prevent having to ensure the two patterns' templates match.
+
+\1f
+File: gccint.info, Node: Including Patterns, Next: Peephole Definitions, Prev: Insn Splitting, Up: Machine Desc
+
+9.16 Including Patterns in Machine Descriptions.
+================================================
+
+The `include' pattern tells the compiler tools where to look for
+patterns that are in files other than in the file `.md'. This is used
+only at build time and there is no preprocessing allowed.
+
+ It looks like:
+
+
+ (include
+ PATHNAME)
+
+ For example:
+
+
+ (include "filestuff")
+
+ Where PATHNAME is a string that specifies the the location of the
+file, specifies the include file to be in
+`gcc/config/target/filestuff'. The directory `gcc/config/target' is
+regarded as the default directory.
+
+ Machine descriptions may be split up into smaller more manageable
+subsections and placed into subdirectories.
+
+ By specifying:
+
+
+ (include "BOGUS/filestuff")
+
+ the include file is specified to be in
+`gcc/config/TARGET/BOGUS/filestuff'.
+
+ Specifying an absolute path for the include file such as;
+
+ (include "/u2/BOGUS/filestuff")
+ is permitted but is not encouraged.
+
+9.16.1 RTL Generation Tool Options for Directory Search
+-------------------------------------------------------
+
+The `-IDIR' option specifies directories to search for machine
+descriptions. For example:
+
+
+ genrecog -I/p1/abc/proc1 -I/p2/abcd/pro2 target.md
+
+ Add the directory DIR to the head of the list of directories to be
+searched for header files. This can be used to override a system
+machine definition file, substituting your own version, since these
+directories are searched before the default machine description file
+directories. If you use more than one `-I' option, the directories are
+scanned in left-to-right order; the standard default directory come
+after.
+
+\1f
+File: gccint.info, Node: Peephole Definitions, Next: Insn Attributes, Prev: Including Patterns, Up: Machine Desc
+
+9.17 Machine-Specific Peephole Optimizers
+=========================================
+
+In addition to instruction patterns the `md' file may contain
+definitions of machine-specific peephole optimizations.
+
+ The combiner does not notice certain peephole optimizations when the
+data flow in the program does not suggest that it should try them. For
+example, sometimes two consecutive insns related in purpose can be
+combined even though the second one does not appear to use a register
+computed in the first one. A machine-specific peephole optimizer can
+detect such opportunities.
-Test Suites
-===========
+ There are two forms of peephole definitions that may be used. The
+original `define_peephole' is run at assembly output time to match
+insns and substitute assembly text. Use of `define_peephole' is
+deprecated.
- GCC contains several test suites to help maintain compiler quality.
-Most of the runtime libraries and language front ends in GCC have test
-suites. Currently only the C language test suites are documented here;
-FIXME: document the others.
+ A newer `define_peephole2' matches insns and substitutes new insns.
+The `peephole2' pass is run after register allocation but before
+scheduling, which may result in much better code for targets that do
+scheduling.
* Menu:
-* Test Idioms:: Idioms used in test suite code.
-* C Tests:: The C language test suites.
-* libgcj Tests:: The Java library test suites.
+* define_peephole:: RTL to Text Peephole Optimizers
+* define_peephole2:: RTL to RTL Peephole Optimizers
\1f
-File: gccint.info, Node: Test Idioms, Next: C Tests, Up: Test Suites
+File: gccint.info, Node: define_peephole, Next: define_peephole2, Up: Peephole Definitions
+
+9.17.1 RTL to Text Peephole Optimizers
+--------------------------------------
+
+A definition looks like this:
+
+ (define_peephole
+ [INSN-PATTERN-1
+ INSN-PATTERN-2
+ ...]
+ "CONDITION"
+ "TEMPLATE"
+ "OPTIONAL-INSN-ATTRIBUTES")
+
+The last string operand may be omitted if you are not using any
+machine-specific information in this machine description. If present,
+it must obey the same rules as in a `define_insn'.
+
+ In this skeleton, INSN-PATTERN-1 and so on are patterns to match
+consecutive insns. The optimization applies to a sequence of insns when
+INSN-PATTERN-1 matches the first one, INSN-PATTERN-2 matches the next,
+and so on.
+
+ Each of the insns matched by a peephole must also match a
+`define_insn'. Peepholes are checked only at the last stage just
+before code generation, and only optionally. Therefore, any insn which
+would match a peephole but no `define_insn' will cause a crash in code
+generation in an unoptimized compilation, or at various optimization
+stages.
+
+ The operands of the insns are matched with `match_operands',
+`match_operator', and `match_dup', as usual. What is not usual is that
+the operand numbers apply to all the insn patterns in the definition.
+So, you can check for identical operands in two insns by using
+`match_operand' in one insn and `match_dup' in the other.
+
+ The operand constraints used in `match_operand' patterns do not have
+any direct effect on the applicability of the peephole, but they will
+be validated afterward, so make sure your constraints are general enough
+to apply whenever the peephole matches. If the peephole matches but
+the constraints are not satisfied, the compiler will crash.
+
+ It is safe to omit constraints in all the operands of the peephole;
+or you can write constraints which serve as a double-check on the
+criteria previously tested.
+
+ Once a sequence of insns matches the patterns, the CONDITION is
+checked. This is a C expression which makes the final decision whether
+to perform the optimization (we do so if the expression is nonzero). If
+CONDITION is omitted (in other words, the string is empty) then the
+optimization is applied to every sequence of insns that matches the
+patterns.
+
+ The defined peephole optimizations are applied after register
+allocation is complete. Therefore, the peephole definition can check
+which operands have ended up in which kinds of registers, just by
+looking at the operands.
+
+ The way to refer to the operands in CONDITION is to write
+`operands[I]' for operand number I (as matched by `(match_operand I
+...)'). Use the variable `insn' to refer to the last of the insns
+being matched; use `prev_active_insn' to find the preceding insns.
+
+ When optimizing computations with intermediate results, you can use
+CONDITION to match only when the intermediate results are not used
+elsewhere. Use the C expression `dead_or_set_p (INSN, OP)', where INSN
+is the insn in which you expect the value to be used for the last time
+(from the value of `insn', together with use of `prev_nonnote_insn'),
+and OP is the intermediate value (from `operands[I]').
+
+ Applying the optimization means replacing the sequence of insns with
+one new insn. The TEMPLATE controls ultimate output of assembler code
+for this combined insn. It works exactly like the template of a
+`define_insn'. Operand numbers in this template are the same ones used
+in matching the original sequence of insns.
+
+ The result of a defined peephole optimizer does not need to match
+any of the insn patterns in the machine description; it does not even
+have an opportunity to match them. The peephole optimizer definition
+itself serves as the insn pattern to control how the insn is output.
+
+ Defined peephole optimizers are run as assembler code is being
+output, so the insns they produce are never combined or rearranged in
+any way.
+
+ Here is an example, taken from the 68000 machine description:
+
+ (define_peephole
+ [(set (reg:SI 15) (plus:SI (reg:SI 15) (const_int 4)))
+ (set (match_operand:DF 0 "register_operand" "=f")
+ (match_operand:DF 1 "register_operand" "ad"))]
+ "FP_REG_P (operands[0]) && ! FP_REG_P (operands[1])"
+ {
+ rtx xoperands[2];
+ xoperands[1] = gen_rtx (REG, SImode, REGNO (operands[1]) + 1);
+ #ifdef MOTOROLA
+ output_asm_insn ("move.l %1,(sp)", xoperands);
+ output_asm_insn ("move.l %1,-(sp)", operands);
+ return "fmove.d (sp)+,%0";
+ #else
+ output_asm_insn ("movel %1,sp@", xoperands);
+ output_asm_insn ("movel %1,sp@-", operands);
+ return "fmoved sp@+,%0";
+ #endif
+ })
+
+ The effect of this optimization is to change
+
+ jbsr _foobar
+ addql #4,sp
+ movel d1,sp@-
+ movel d0,sp@-
+ fmoved sp@+,fp0
+
+into
+
+ jbsr _foobar
+ movel d1,sp@
+ movel d0,sp@-
+ fmoved sp@+,fp0
+
+ INSN-PATTERN-1 and so on look _almost_ like the second operand of
+`define_insn'. There is one important difference: the second operand
+of `define_insn' consists of one or more RTX's enclosed in square
+brackets. Usually, there is only one: then the same action can be
+written as an element of a `define_peephole'. But when there are
+multiple actions in a `define_insn', they are implicitly enclosed in a
+`parallel'. Then you must explicitly write the `parallel', and the
+square brackets within it, in the `define_peephole'. Thus, if an insn
+pattern looks like this,
+
+ (define_insn "divmodsi4"
+ [(set (match_operand:SI 0 "general_operand" "=d")
+ (div:SI (match_operand:SI 1 "general_operand" "0")
+ (match_operand:SI 2 "general_operand" "dmsK")))
+ (set (match_operand:SI 3 "general_operand" "=d")
+ (mod:SI (match_dup 1) (match_dup 2)))]
+ "TARGET_68020"
+ "divsl%.l %2,%3:%0")
+
+then the way to mention this insn in a peephole is as follows:
+
+ (define_peephole
+ [...
+ (parallel
+ [(set (match_operand:SI 0 "general_operand" "=d")
+ (div:SI (match_operand:SI 1 "general_operand" "0")
+ (match_operand:SI 2 "general_operand" "dmsK")))
+ (set (match_operand:SI 3 "general_operand" "=d")
+ (mod:SI (match_dup 1) (match_dup 2)))])
+ ...]
+ ...)
-Idioms Used in Test Suite Code
-------------------------------
+\1f
+File: gccint.info, Node: define_peephole2, Prev: define_peephole, Up: Peephole Definitions
+
+9.17.2 RTL to RTL Peephole Optimizers
+-------------------------------------
+
+The `define_peephole2' definition tells the compiler how to substitute
+one sequence of instructions for another sequence, what additional
+scratch registers may be needed and what their lifetimes must be.
+
+ (define_peephole2
+ [INSN-PATTERN-1
+ INSN-PATTERN-2
+ ...]
+ "CONDITION"
+ [NEW-INSN-PATTERN-1
+ NEW-INSN-PATTERN-2
+ ...]
+ "PREPARATION-STATEMENTS")
+
+ The definition is almost identical to `define_split' (*note Insn
+Splitting::) except that the pattern to match is not a single
+instruction, but a sequence of instructions.
+
+ It is possible to request additional scratch registers for use in the
+output template. If appropriate registers are not free, the pattern
+will simply not match.
+
+ Scratch registers are requested with a `match_scratch' pattern at
+the top level of the input pattern. The allocated register (initially)
+will be dead at the point requested within the original sequence. If
+the scratch is used at more than a single point, a `match_dup' pattern
+at the top level of the input pattern marks the last position in the
+input sequence at which the register must be available.
+
+ Here is an example from the IA-32 machine description:
+
+ (define_peephole2
+ [(match_scratch:SI 2 "r")
+ (parallel [(set (match_operand:SI 0 "register_operand" "")
+ (match_operator:SI 3 "arith_or_logical_operator"
+ [(match_dup 0)
+ (match_operand:SI 1 "memory_operand" "")]))
+ (clobber (reg:CC 17))])]
+ "! optimize_size && ! TARGET_READ_MODIFY"
+ [(set (match_dup 2) (match_dup 1))
+ (parallel [(set (match_dup 0)
+ (match_op_dup 3 [(match_dup 0) (match_dup 2)]))
+ (clobber (reg:CC 17))])]
+ "")
+
+This pattern tries to split a load from its use in the hopes that we'll
+be able to schedule around the memory load latency. It allocates a
+single `SImode' register of class `GENERAL_REGS' (`"r"') that needs to
+be live only at the point just before the arithmetic.
+
+ A real example requiring extended scratch lifetimes is harder to
+come by, so here's a silly made-up example:
+
+ (define_peephole2
+ [(match_scratch:SI 4 "r")
+ (set (match_operand:SI 0 "" "") (match_operand:SI 1 "" ""))
+ (set (match_operand:SI 2 "" "") (match_dup 1))
+ (match_dup 4)
+ (set (match_operand:SI 3 "" "") (match_dup 1))]
+ "/* determine 1 does not overlap 0 and 2 */"
+ [(set (match_dup 4) (match_dup 1))
+ (set (match_dup 0) (match_dup 4))
+ (set (match_dup 2) (match_dup 4))]
+ (set (match_dup 3) (match_dup 4))]
+ "")
+
+If we had not added the `(match_dup 4)' in the middle of the input
+sequence, it might have been the case that the register we chose at the
+beginning of the sequence is killed by the first or second `set'.
+
+\1f
+File: gccint.info, Node: Insn Attributes, Next: Conditional Execution, Prev: Peephole Definitions, Up: Machine Desc
+
+9.18 Instruction Attributes
+===========================
+
+In addition to describing the instruction supported by the target
+machine, the `md' file also defines a group of "attributes" and a set of
+values for each. Every generated insn is assigned a value for each
+attribute. One possible attribute would be the effect that the insn
+has on the machine's condition code. This attribute can then be used
+by `NOTICE_UPDATE_CC' to track the condition codes.
+
+* Menu:
+
+* Defining Attributes:: Specifying attributes and their values.
+* Expressions:: Valid expressions for attribute values.
+* Tagging Insns:: Assigning attribute values to insns.
+* Attr Example:: An example of assigning attributes.
+* Insn Lengths:: Computing the length of insns.
+* Constant Attributes:: Defining attributes that are constant.
+* Delay Slots:: Defining delay slots required for a machine.
+* Function Units:: Specifying information for insn scheduling.
+
+\1f
+File: gccint.info, Node: Defining Attributes, Next: Expressions, Up: Insn Attributes
+
+9.18.1 Defining Attributes and their Values
+-------------------------------------------
+
+The `define_attr' expression is used to define each attribute required
+by the target machine. It looks like:
+
+ (define_attr NAME LIST-OF-VALUES DEFAULT)
+
+ NAME is a string specifying the name of the attribute being defined.
+
+ LIST-OF-VALUES is either a string that specifies a comma-separated
+list of values that can be assigned to the attribute, or a null string
+to indicate that the attribute takes numeric values.
+
+ DEFAULT is an attribute expression that gives the value of this
+attribute for insns that match patterns whose definition does not
+include an explicit value for this attribute. *Note Attr Example::,
+for more information on the handling of defaults. *Note Constant
+Attributes::, for information on attributes that do not depend on any
+particular insn.
+
+ For each defined attribute, a number of definitions are written to
+the `insn-attr.h' file. For cases where an explicit set of values is
+specified for an attribute, the following are defined:
+
+ * A `#define' is written for the symbol `HAVE_ATTR_NAME'.
+
+ * An enumeral class is defined for `attr_NAME' with elements of the
+ form `UPPER-NAME_UPPER-VALUE' where the attribute name and value
+ are first converted to upper case.
+
+ * A function `get_attr_NAME' is defined that is passed an insn and
+ returns the attribute value for that insn.
+
+ For example, if the following is present in the `md' file:
+
+ (define_attr "type" "branch,fp,load,store,arith" ...)
+
+the following lines will be written to the file `insn-attr.h'.
+
+ #define HAVE_ATTR_type
+ enum attr_type {TYPE_BRANCH, TYPE_FP, TYPE_LOAD,
+ TYPE_STORE, TYPE_ARITH};
+ extern enum attr_type get_attr_type ();
+
+ If the attribute takes numeric values, no `enum' type will be
+defined and the function to obtain the attribute's value will return
+`int'.
+
+\1f
+File: gccint.info, Node: Expressions, Next: Tagging Insns, Prev: Defining Attributes, Up: Insn Attributes
- In the `gcc.c-torture' test suites, test cases are commonly named
-after the date on which they were added. This allows people to tell at
-a glance whether a test failure is because of a recently found bug that
-has not yet been fixed, or whether it may be a regression. In other
-test suites, more descriptive names are used. In general C test cases
-have a trailing `-N.c', starting with `-1.c', in case other test cases
-with similar names are added later.
-
- Test cases should use `abort ()' to indicate failure and `exit (0)'
-for success; on some targets these may be redefined to indicate failure
-and success in other ways.
-
- In the `gcc.dg' test suite, it is often necessary to test that an
-error is indeed a hard error and not just a warning--for example, where
-it is a constraint violation in the C standard, which must become an
-error with `-pedantic-errors'. The following idiom, where the first
-line shown is line LINE of the file and the line that generates the
-error, is used for this:
-
- /* { dg-bogus "warning" "warning in place of error" } */
- /* { dg-error "REGEXP" "MESSAGE" { target *-*-* } LINE } */
-
- It may be necessary to check that an expression is an integer
-constant expression and has a certain value. To check that `E' has
-value `V', an idiom similar to the following is used:
-
- char x[((E) == (V) ? 1 : -1)];
-
- In `gcc.dg' tests, `__typeof__' is sometimes used to make assertions
-about the types of expressions. See, for example,
-`gcc.dg/c99-condexpr-1.c'. The more subtle uses depend on the exact
-rules for the types of conditional expressions in the C standard; see,
-for example, `gcc.dg/c99-intconst-1.c'.
-
- It is useful to be able to test that optimizations are being made
-properly. This cannot be done in all cases, but it can be done where
-the optimization will lead to code being optimized away (for example,
-where flow analysis or alias analysis should show that certain code
-cannot be called) or to functions not being called because they have
-been expanded as built-in functions. Such tests go in
-`gcc.c-torture/execute'. Where code should be optimized away, a call
-to a nonexistent function such as `link_failure ()' may be inserted; a
-definition
-
- #ifndef __OPTIMIZE__
- void
- link_failure (void)
+9.18.2 Attribute Expressions
+----------------------------
+
+RTL expressions used to define attributes use the codes described above
+plus a few specific to attribute definitions, to be discussed below.
+Attribute value expressions must have one of the following forms:
+
+`(const_int I)'
+ The integer I specifies the value of a numeric attribute. I must
+ be non-negative.
+
+ The value of a numeric attribute can be specified either with a
+ `const_int', or as an integer represented as a string in
+ `const_string', `eq_attr' (see below), `attr', `symbol_ref',
+ simple arithmetic expressions, and `set_attr' overrides on
+ specific instructions (*note Tagging Insns::).
+
+`(const_string VALUE)'
+ The string VALUE specifies a constant attribute value. If VALUE
+ is specified as `"*"', it means that the default value of the
+ attribute is to be used for the insn containing this expression.
+ `"*"' obviously cannot be used in the DEFAULT expression of a
+ `define_attr'.
+
+ If the attribute whose value is being specified is numeric, VALUE
+ must be a string containing a non-negative integer (normally
+ `const_int' would be used in this case). Otherwise, it must
+ contain one of the valid values for the attribute.
+
+`(if_then_else TEST TRUE-VALUE FALSE-VALUE)'
+ TEST specifies an attribute test, whose format is defined below.
+ The value of this expression is TRUE-VALUE if TEST is true,
+ otherwise it is FALSE-VALUE.
+
+`(cond [TEST1 VALUE1 ...] DEFAULT)'
+ The first operand of this expression is a vector containing an even
+ number of expressions and consisting of pairs of TEST and VALUE
+ expressions. The value of the `cond' expression is that of the
+ VALUE corresponding to the first true TEST expression. If none of
+ the TEST expressions are true, the value of the `cond' expression
+ is that of the DEFAULT expression.
+
+ TEST expressions can have one of the following forms:
+
+`(const_int I)'
+ This test is true if I is nonzero and false otherwise.
+
+`(not TEST)'
+`(ior TEST1 TEST2)'
+`(and TEST1 TEST2)'
+ These tests are true if the indicated logical function is true.
+
+`(match_operand:M N PRED CONSTRAINTS)'
+ This test is true if operand N of the insn whose attribute value
+ is being determined has mode M (this part of the test is ignored
+ if M is `VOIDmode') and the function specified by the string PRED
+ returns a nonzero value when passed operand N and mode M (this
+ part of the test is ignored if PRED is the null string).
+
+ The CONSTRAINTS operand is ignored and should be the null string.
+
+`(le ARITH1 ARITH2)'
+`(leu ARITH1 ARITH2)'
+`(lt ARITH1 ARITH2)'
+`(ltu ARITH1 ARITH2)'
+`(gt ARITH1 ARITH2)'
+`(gtu ARITH1 ARITH2)'
+`(ge ARITH1 ARITH2)'
+`(geu ARITH1 ARITH2)'
+`(ne ARITH1 ARITH2)'
+`(eq ARITH1 ARITH2)'
+ These tests are true if the indicated comparison of the two
+ arithmetic expressions is true. Arithmetic expressions are formed
+ with `plus', `minus', `mult', `div', `mod', `abs', `neg', `and',
+ `ior', `xor', `not', `ashift', `lshiftrt', and `ashiftrt'
+ expressions.
+
+ `const_int' and `symbol_ref' are always valid terms (*note Insn
+ Lengths::,for additional forms). `symbol_ref' is a string
+ denoting a C expression that yields an `int' when evaluated by the
+ `get_attr_...' routine. It should normally be a global variable.
+
+`(eq_attr NAME VALUE)'
+ NAME is a string specifying the name of an attribute.
+
+ VALUE is a string that is either a valid value for attribute NAME,
+ a comma-separated list of values, or `!' followed by a value or
+ list. If VALUE does not begin with a `!', this test is true if
+ the value of the NAME attribute of the current insn is in the list
+ specified by VALUE. If VALUE begins with a `!', this test is true
+ if the attribute's value is _not_ in the specified list.
+
+ For example,
+
+ (eq_attr "type" "load,store")
+
+ is equivalent to
+
+ (ior (eq_attr "type" "load") (eq_attr "type" "store"))
+
+ If NAME specifies an attribute of `alternative', it refers to the
+ value of the compiler variable `which_alternative' (*note Output
+ Statement::) and the values must be small integers. For example,
+
+ (eq_attr "alternative" "2,3")
+
+ is equivalent to
+
+ (ior (eq (symbol_ref "which_alternative") (const_int 2))
+ (eq (symbol_ref "which_alternative") (const_int 3)))
+
+ Note that, for most attributes, an `eq_attr' test is simplified in
+ cases where the value of the attribute being tested is known for
+ all insns matching a particular pattern. This is by far the most
+ common case.
+
+`(attr_flag NAME)'
+ The value of an `attr_flag' expression is true if the flag
+ specified by NAME is true for the `insn' currently being scheduled.
+
+ NAME is a string specifying one of a fixed set of flags to test.
+ Test the flags `forward' and `backward' to determine the direction
+ of a conditional branch. Test the flags `very_likely', `likely',
+ `very_unlikely', and `unlikely' to determine if a conditional
+ branch is expected to be taken.
+
+ If the `very_likely' flag is true, then the `likely' flag is also
+ true. Likewise for the `very_unlikely' and `unlikely' flags.
+
+ This example describes a conditional branch delay slot which can
+ be nullified for forward branches that are taken (annul-true) or
+ for backward branches which are not taken (annul-false).
+
+ (define_delay (eq_attr "type" "cbranch")
+ [(eq_attr "in_branch_delay" "true")
+ (and (eq_attr "in_branch_delay" "true")
+ (attr_flag "forward"))
+ (and (eq_attr "in_branch_delay" "true")
+ (attr_flag "backward"))])
+
+ The `forward' and `backward' flags are false if the current `insn'
+ being scheduled is not a conditional branch.
+
+ The `very_likely' and `likely' flags are true if the `insn' being
+ scheduled is not a conditional branch. The `very_unlikely' and
+ `unlikely' flags are false if the `insn' being scheduled is not a
+ conditional branch.
+
+ `attr_flag' is only used during delay slot scheduling and has no
+ meaning to other passes of the compiler.
+
+`(attr NAME)'
+ The value of another attribute is returned. This is most useful
+ for numeric attributes, as `eq_attr' and `attr_flag' produce more
+ efficient code for non-numeric attributes.
+
+\1f
+File: gccint.info, Node: Tagging Insns, Next: Attr Example, Prev: Expressions, Up: Insn Attributes
+
+9.18.3 Assigning Attribute Values to Insns
+------------------------------------------
+
+The value assigned to an attribute of an insn is primarily determined by
+which pattern is matched by that insn (or which `define_peephole'
+generated it). Every `define_insn' and `define_peephole' can have an
+optional last argument to specify the values of attributes for matching
+insns. The value of any attribute not specified in a particular insn
+is set to the default value for that attribute, as specified in its
+`define_attr'. Extensive use of default values for attributes permits
+the specification of the values for only one or two attributes in the
+definition of most insn patterns, as seen in the example in the next
+section.
+
+ The optional last argument of `define_insn' and `define_peephole' is
+a vector of expressions, each of which defines the value for a single
+attribute. The most general way of assigning an attribute's value is
+to use a `set' expression whose first operand is an `attr' expression
+giving the name of the attribute being set. The second operand of the
+`set' is an attribute expression (*note Expressions::) giving the value
+of the attribute.
+
+ When the attribute value depends on the `alternative' attribute
+(i.e., which is the applicable alternative in the constraint of the
+insn), the `set_attr_alternative' expression can be used. It allows
+the specification of a vector of attribute expressions, one for each
+alternative.
+
+ When the generality of arbitrary attribute expressions is not
+required, the simpler `set_attr' expression can be used, which allows
+specifying a string giving either a single attribute value or a list of
+attribute values, one for each alternative.
+
+ The form of each of the above specifications is shown below. In
+each case, NAME is a string specifying the attribute to be set.
+
+`(set_attr NAME VALUE-STRING)'
+ VALUE-STRING is either a string giving the desired attribute value,
+ or a string containing a comma-separated list giving the values for
+ succeeding alternatives. The number of elements must match the
+ number of alternatives in the constraint of the insn pattern.
+
+ Note that it may be useful to specify `*' for some alternative, in
+ which case the attribute will assume its default value for insns
+ matching that alternative.
+
+`(set_attr_alternative NAME [VALUE1 VALUE2 ...])'
+ Depending on the alternative of the insn, the value will be one of
+ the specified values. This is a shorthand for using a `cond' with
+ tests on the `alternative' attribute.
+
+`(set (attr NAME) VALUE)'
+ The first operand of this `set' must be the special RTL expression
+ `attr', whose sole operand is a string giving the name of the
+ attribute being set. VALUE is the value of the attribute.
+
+ The following shows three different ways of representing the same
+attribute value specification:
+
+ (set_attr "type" "load,store,arith")
+
+ (set_attr_alternative "type"
+ [(const_string "load") (const_string "store")
+ (const_string "arith")])
+
+ (set (attr "type")
+ (cond [(eq_attr "alternative" "1") (const_string "load")
+ (eq_attr "alternative" "2") (const_string "store")]
+ (const_string "arith")))
+
+ The `define_asm_attributes' expression provides a mechanism to
+specify the attributes assigned to insns produced from an `asm'
+statement. It has the form:
+
+ (define_asm_attributes [ATTR-SETS])
+
+where ATTR-SETS is specified the same as for both the `define_insn' and
+the `define_peephole' expressions.
+
+ These values will typically be the "worst case" attribute values.
+For example, they might indicate that the condition code will be
+clobbered.
+
+ A specification for a `length' attribute is handled specially. The
+way to compute the length of an `asm' insn is to multiply the length
+specified in the expression `define_asm_attributes' by the number of
+machine instructions specified in the `asm' statement, determined by
+counting the number of semicolons and newlines in the string.
+Therefore, the value of the `length' attribute specified in a
+`define_asm_attributes' should be the maximum possible length of a
+single machine instruction.
+
+\1f
+File: gccint.info, Node: Attr Example, Next: Insn Lengths, Prev: Tagging Insns, Up: Insn Attributes
+
+9.18.4 Example of Attribute Specifications
+------------------------------------------
+
+The judicious use of defaulting is important in the efficient use of
+insn attributes. Typically, insns are divided into "types" and an
+attribute, customarily called `type', is used to represent this value.
+This attribute is normally used only to define the default value for
+other attributes. An example will clarify this usage.
+
+ Assume we have a RISC machine with a condition code and in which only
+full-word operations are performed in registers. Let us assume that we
+can divide all insns into loads, stores, (integer) arithmetic
+operations, floating point operations, and branches.
+
+ Here we will concern ourselves with determining the effect of an
+insn on the condition code and will limit ourselves to the following
+possible effects: The condition code can be set unpredictably
+(clobbered), not be changed, be set to agree with the results of the
+operation, or only changed if the item previously set into the
+condition code has been modified.
+
+ Here is part of a sample `md' file for such a machine:
+
+ (define_attr "type" "load,store,arith,fp,branch" (const_string "arith"))
+
+ (define_attr "cc" "clobber,unchanged,set,change0"
+ (cond [(eq_attr "type" "load")
+ (const_string "change0")
+ (eq_attr "type" "store,branch")
+ (const_string "unchanged")
+ (eq_attr "type" "arith")
+ (if_then_else (match_operand:SI 0 "" "")
+ (const_string "set")
+ (const_string "clobber"))]
+ (const_string "clobber")))
+
+ (define_insn ""
+ [(set (match_operand:SI 0 "general_operand" "=r,r,m")
+ (match_operand:SI 1 "general_operand" "r,m,r"))]
+ ""
+ "@
+ move %0,%1
+ load %0,%1
+ store %0,%1"
+ [(set_attr "type" "arith,load,store")])
+
+ Note that we assume in the above example that arithmetic operations
+performed on quantities smaller than a machine word clobber the
+condition code since they will set the condition code to a value
+corresponding to the full-word result.
+
+\1f
+File: gccint.info, Node: Insn Lengths, Next: Constant Attributes, Prev: Attr Example, Up: Insn Attributes
+
+9.18.5 Computing the Length of an Insn
+--------------------------------------
+
+For many machines, multiple types of branch instructions are provided,
+each for different length branch displacements. In most cases, the
+assembler will choose the correct instruction to use. However, when
+the assembler cannot do so, GCC can when a special attribute, the
+`length' attribute, is defined. This attribute must be defined to have
+numeric values by specifying a null string in its `define_attr'.
+
+ In the case of the `length' attribute, two additional forms of
+arithmetic terms are allowed in test expressions:
+
+`(match_dup N)'
+ This refers to the address of operand N of the current insn, which
+ must be a `label_ref'.
+
+`(pc)'
+ This refers to the address of the _current_ insn. It might have
+ been more consistent with other usage to make this the address of
+ the _next_ insn but this would be confusing because the length of
+ the current insn is to be computed.
+
+ For normal insns, the length will be determined by value of the
+`length' attribute. In the case of `addr_vec' and `addr_diff_vec' insn
+patterns, the length is computed as the number of vectors multiplied by
+the size of each vector.
+
+ Lengths are measured in addressable storage units (bytes).
+
+ The following macros can be used to refine the length computation:
+
+`FIRST_INSN_ADDRESS'
+ When the `length' insn attribute is used, this macro specifies the
+ value to be assigned to the address of the first insn in a
+ function. If not specified, 0 is used.
+
+`ADJUST_INSN_LENGTH (INSN, LENGTH)'
+ If defined, modifies the length assigned to instruction INSN as a
+ function of the context in which it is used. LENGTH is an lvalue
+ that contains the initially computed length of the insn and should
+ be updated with the correct length of the insn.
+
+ This macro will normally not be required. A case in which it is
+ required is the ROMP. On this machine, the size of an `addr_vec'
+ insn must be increased by two to compensate for the fact that
+ alignment may be required.
+
+ The routine that returns `get_attr_length' (the value of the
+`length' attribute) can be used by the output routine to determine the
+form of the branch instruction to be written, as the example below
+illustrates.
+
+ As an example of the specification of variable-length branches,
+consider the IBM 360. If we adopt the convention that a register will
+be set to the starting address of a function, we can jump to labels
+within 4k of the start using a four-byte instruction. Otherwise, we
+need a six-byte sequence to load the address from memory and then
+branch to it.
+
+ On such a machine, a pattern for a branch instruction might be
+specified as follows:
+
+ (define_insn "jump"
+ [(set (pc)
+ (label_ref (match_operand 0 "" "")))]
+ ""
{
- abort ();
+ return (get_attr_length (insn) == 4
+ ? "b %l0" : "l r15,=a(%l0); br r15");
}
- #endif
+ [(set (attr "length")
+ (if_then_else (lt (match_dup 0) (const_int 4096))
+ (const_int 4)
+ (const_int 6)))])
+
+\1f
+File: gccint.info, Node: Constant Attributes, Next: Delay Slots, Prev: Insn Lengths, Up: Insn Attributes
+
+9.18.6 Constant Attributes
+--------------------------
+
+A special form of `define_attr', where the expression for the default
+value is a `const' expression, indicates an attribute that is constant
+for a given run of the compiler. Constant attributes may be used to
+specify which variety of processor is used. For example,
+
+ (define_attr "cpu" "m88100,m88110,m88000"
+ (const
+ (cond [(symbol_ref "TARGET_88100") (const_string "m88100")
+ (symbol_ref "TARGET_88110") (const_string "m88110")]
+ (const_string "m88000"))))
+
+ (define_attr "memory" "fast,slow"
+ (const
+ (if_then_else (symbol_ref "TARGET_FAST_MEM")
+ (const_string "fast")
+ (const_string "slow"))))
+
+ The routine generated for constant attributes has no parameters as it
+does not depend on any particular insn. RTL expressions used to define
+the value of a constant attribute may use the `symbol_ref' form, but
+may not use either the `match_operand' form or `eq_attr' forms
+involving insn attributes.
+
+\1f
+File: gccint.info, Node: Delay Slots, Next: Function Units, Prev: Constant Attributes, Up: Insn Attributes
+
+9.18.7 Delay Slot Scheduling
+----------------------------
-will also be needed so that linking still succeeds when the test is run
-without optimization. When all calls to a built-in function should
-have been optimized and no calls to the non-built-in version of the
-function should remain, that function may be defined as `static' to
-call `abort ()' (although redeclaring a function as static may not work
-on all targets).
+The insn attribute mechanism can be used to specify the requirements for
+delay slots, if any, on a target machine. An instruction is said to
+require a "delay slot" if some instructions that are physically after
+the instruction are executed as if they were located before it.
+Classic examples are branch and call instructions, which often execute
+the following instruction before the branch or call is performed.
+
+ On some machines, conditional branch instructions can optionally
+"annul" instructions in the delay slot. This means that the
+instruction will not be executed for certain branch outcomes. Both
+instructions that annul if the branch is true and instructions that
+annul if the branch is false are supported.
+
+ Delay slot scheduling differs from instruction scheduling in that
+determining whether an instruction needs a delay slot is dependent only
+on the type of instruction being generated, not on data flow between the
+instructions. See the next section for a discussion of data-dependent
+instruction scheduling.
+
+ The requirement of an insn needing one or more delay slots is
+indicated via the `define_delay' expression. It has the following form:
+
+ (define_delay TEST
+ [DELAY-1 ANNUL-TRUE-1 ANNUL-FALSE-1
+ DELAY-2 ANNUL-TRUE-2 ANNUL-FALSE-2
+ ...])
+
+ TEST is an attribute test that indicates whether this `define_delay'
+applies to a particular insn. If so, the number of required delay
+slots is determined by the length of the vector specified as the second
+argument. An insn placed in delay slot N must satisfy attribute test
+DELAY-N. ANNUL-TRUE-N is an attribute test that specifies which insns
+may be annulled if the branch is true. Similarly, ANNUL-FALSE-N
+specifies which insns in the delay slot may be annulled if the branch
+is false. If annulling is not supported for that delay slot, `(nil)'
+should be coded.
+
+ For example, in the common case where branch and call insns require
+a single delay slot, which may contain any insn other than a branch or
+call, the following would be placed in the `md' file:
+
+ (define_delay (eq_attr "type" "branch,call")
+ [(eq_attr "type" "!branch,call") (nil) (nil)])
+
+ Multiple `define_delay' expressions may be specified. In this case,
+each such expression specifies different delay slot requirements and
+there must be no insn for which tests in two `define_delay' expressions
+are both true.
+
+ For example, if we have a machine that requires one delay slot for
+branches but two for calls, no delay slot can contain a branch or call
+insn, and any valid insn in the delay slot for the branch can be
+annulled if the branch is true, we might represent this as follows:
+
+ (define_delay (eq_attr "type" "branch")
+ [(eq_attr "type" "!branch,call")
+ (eq_attr "type" "!branch,call")
+ (nil)])
+
+ (define_delay (eq_attr "type" "call")
+ [(eq_attr "type" "!branch,call") (nil) (nil)
+ (eq_attr "type" "!branch,call") (nil) (nil)])
- FIXME: discuss non-C test suites here.
+\1f
+File: gccint.info, Node: Function Units, Prev: Delay Slots, Up: Insn Attributes
+
+9.18.8 Specifying Function Units
+--------------------------------
+
+On most RISC machines, there are instructions whose results are not
+available for a specific number of cycles. Common cases are
+instructions that load data from memory. On many machines, a pipeline
+stall will result if the data is referenced too soon after the load
+instruction.
+
+ In addition, many newer microprocessors have multiple function
+units, usually one for integer and one for floating point, and often
+will incur pipeline stalls when a result that is needed is not yet
+ready.
+
+ The descriptions in this section allow the specification of how much
+time must elapse between the execution of an instruction and the time
+when its result is used. It also allows specification of when the
+execution of an instruction will delay execution of similar instructions
+due to function unit conflicts.
+
+ For the purposes of the specifications in this section, a machine is
+divided into "function units", each of which execute a specific class
+of instructions in first-in-first-out order. Function units that
+accept one instruction each cycle and allow a result to be used in the
+succeeding instruction (usually via forwarding) need not be specified.
+Classic RISC microprocessors will normally have a single function unit,
+which we can call `memory'. The newer "superscalar" processors will
+often have function units for floating point operations, usually at
+least a floating point adder and multiplier.
+
+ Each usage of a function units by a class of insns is specified with
+a `define_function_unit' expression, which looks like this:
+
+ (define_function_unit NAME MULTIPLICITY SIMULTANEITY
+ TEST READY-DELAY ISSUE-DELAY
+ [CONFLICT-LIST])
+
+ NAME is a string giving the name of the function unit.
+
+ MULTIPLICITY is an integer specifying the number of identical units
+in the processor. If more than one unit is specified, they will be
+scheduled independently. Only truly independent units should be
+counted; a pipelined unit should be specified as a single unit. (The
+only common example of a machine that has multiple function units for a
+single instruction class that are truly independent and not pipelined
+are the two multiply and two increment units of the CDC 6600.)
+
+ SIMULTANEITY specifies the maximum number of insns that can be
+executing in each instance of the function unit simultaneously or zero
+if the unit is pipelined and has no limit.
+
+ All `define_function_unit' definitions referring to function unit
+NAME must have the same name and values for MULTIPLICITY and
+SIMULTANEITY.
+
+ TEST is an attribute test that selects the insns we are describing
+in this definition. Note that an insn may use more than one function
+unit and a function unit may be specified in more than one
+`define_function_unit'.
+
+ READY-DELAY is an integer that specifies the number of cycles after
+which the result of the instruction can be used without introducing any
+stalls.
+
+ ISSUE-DELAY is an integer that specifies the number of cycles after
+the instruction matching the TEST expression begins using this unit
+until a subsequent instruction can begin. A cost of N indicates an N-1
+cycle delay. A subsequent instruction may also be delayed if an
+earlier instruction has a longer READY-DELAY value. This blocking
+effect is computed using the SIMULTANEITY, READY-DELAY, ISSUE-DELAY,
+and CONFLICT-LIST terms. For a normal non-pipelined function unit,
+SIMULTANEITY is one, the unit is taken to block for the READY-DELAY
+cycles of the executing insn, and smaller values of ISSUE-DELAY are
+ignored.
+
+ CONFLICT-LIST is an optional list giving detailed conflict costs for
+this unit. If specified, it is a list of condition test expressions to
+be applied to insns chosen to execute in NAME following the particular
+insn matching TEST that is already executing in NAME. For each insn in
+the list, ISSUE-DELAY specifies the conflict cost; for insns not in the
+list, the cost is zero. If not specified, CONFLICT-LIST defaults to
+all instructions that use the function unit.
+
+ Typical uses of this vector are where a floating point function unit
+can pipeline either single- or double-precision operations, but not
+both, or where a memory unit can pipeline loads, but not stores, etc.
+
+ As an example, consider a classic RISC machine where the result of a
+load instruction is not available for two cycles (a single "delay"
+instruction is required) and where only one load instruction can be
+executed simultaneously. This would be specified as:
+
+ (define_function_unit "memory" 1 1 (eq_attr "type" "load") 2 0)
+
+ For the case of a floating point function unit that can pipeline
+either single or double precision, but not both, the following could be
+specified:
+
+ (define_function_unit
+ "fp" 1 0 (eq_attr "type" "sp_fp") 4 4 [(eq_attr "type" "dp_fp")])
+ (define_function_unit
+ "fp" 1 0 (eq_attr "type" "dp_fp") 4 4 [(eq_attr "type" "sp_fp")])
+
+ *Note_* The scheduler attempts to avoid function unit conflicts and
+uses all the specifications in the `define_function_unit' expression.
+It has recently come to our attention that these specifications may not
+allow modeling of some of the newer "superscalar" processors that have
+insns using multiple pipelined units. These insns will cause a
+potential conflict for the second unit used during their execution and
+there is no way of representing that conflict. We welcome any examples
+of how function unit conflicts work in such processors and suggestions
+for their representation.
+
+\1f
+File: gccint.info, Node: Conditional Execution, Next: Constant Definitions, Prev: Insn Attributes, Up: Machine Desc
+
+9.19 Conditional Execution
+==========================
+
+A number of architectures provide for some form of conditional
+execution, or predication. The hallmark of this feature is the ability
+to nullify most of the instructions in the instruction set. When the
+instruction set is large and not entirely symmetric, it can be quite
+tedious to describe these forms directly in the `.md' file. An
+alternative is the `define_cond_exec' template.
+
+ (define_cond_exec
+ [PREDICATE-PATTERN]
+ "CONDITION"
+ "OUTPUT-TEMPLATE")
+
+ PREDICATE-PATTERN is the condition that must be true for the insn to
+be executed at runtime and should match a relational operator. One can
+use `match_operator' to match several relational operators at once.
+Any `match_operand' operands must have no more than one alternative.
+
+ CONDITION is a C expression that must be true for the generated
+pattern to match.
+
+ OUTPUT-TEMPLATE is a string similar to the `define_insn' output
+template (*note Output Template::), except that the `*' and `@' special
+cases do not apply. This is only useful if the assembly text for the
+predicate is a simple prefix to the main insn. In order to handle the
+general case, there is a global variable `current_insn_predicate' that
+will contain the entire predicate if the current insn is predicated,
+and will otherwise be `NULL'.
+
+ When `define_cond_exec' is used, an implicit reference to the
+`predicable' instruction attribute is made. *Note Insn Attributes::.
+This attribute must be boolean (i.e. have exactly two elements in its
+LIST-OF-VALUES). Further, it must not be used with complex
+expressions. That is, the default and all uses in the insns must be a
+simple constant, not dependent on the alternative or anything else.
+
+ For each `define_insn' for which the `predicable' attribute is true,
+a new `define_insn' pattern will be generated that matches a predicated
+version of the instruction. For example,
+
+ (define_insn "addsi"
+ [(set (match_operand:SI 0 "register_operand" "r")
+ (plus:SI (match_operand:SI 1 "register_operand" "r")
+ (match_operand:SI 2 "register_operand" "r")))]
+ "TEST1"
+ "add %2,%1,%0")
+
+ (define_cond_exec
+ [(ne (match_operand:CC 0 "register_operand" "c")
+ (const_int 0))]
+ "TEST2"
+ "(%0)")
+
+generates a new pattern
+
+ (define_insn ""
+ [(cond_exec
+ (ne (match_operand:CC 3 "register_operand" "c") (const_int 0))
+ (set (match_operand:SI 0 "register_operand" "r")
+ (plus:SI (match_operand:SI 1 "register_operand" "r")
+ (match_operand:SI 2 "register_operand" "r"))))]
+ "(TEST2) && (TEST1)"
+ "(%3) add %2,%1,%0")
+
+\1f
+File: gccint.info, Node: Constant Definitions, Prev: Conditional Execution, Up: Machine Desc
+
+9.20 Constant Definitions
+=========================
+
+Using literal constants inside instruction patterns reduces legibility
+and can be a maintenance problem.
+
+ To overcome this problem, you may use the `define_constants'
+expression. It contains a vector of name-value pairs. From that point
+on, wherever any of the names appears in the MD file, it is as if the
+corresponding value had been written instead. You may use
+`define_constants' multiple times; each appearance adds more constants
+to the table. It is an error to redefine a constant with a different
+value.
+
+ To come back to the a29k load multiple example, instead of
+
+ (define_insn ""
+ [(match_parallel 0 "load_multiple_operation"
+ [(set (match_operand:SI 1 "gpc_reg_operand" "=r")
+ (match_operand:SI 2 "memory_operand" "m"))
+ (use (reg:SI 179))
+ (clobber (reg:SI 179))])]
+ ""
+ "loadm 0,0,%1,%2")
+
+ You could write:
+
+ (define_constants [
+ (R_BP 177)
+ (R_FC 178)
+ (R_CR 179)
+ (R_Q 180)
+ ])
+
+ (define_insn ""
+ [(match_parallel 0 "load_multiple_operation"
+ [(set (match_operand:SI 1 "gpc_reg_operand" "=r")
+ (match_operand:SI 2 "memory_operand" "m"))
+ (use (reg:SI R_CR))
+ (clobber (reg:SI R_CR))])]
+ ""
+ "loadm 0,0,%1,%2")
+
+ The constants that are defined with a define_constant are also output
+in the insn-codes.h header file as #defines.
\1f
-File: gccint.info, Node: C Tests, Next: libgcj Tests, Prev: Test Idioms, Up: Test Suites
+File: gccint.info, Node: Target Macros, Next: Host Config, Prev: Machine Desc, Up: Top
+
+10 Target Description Macros and Functions
+******************************************
+
+In addition to the file `MACHINE.md', a machine description includes a
+C header file conventionally given the name `MACHINE.h' and a C source
+file named `MACHINE.c'. The header file defines numerous macros that
+convey the information about the target machine that does not fit into
+the scheme of the `.md' file. The file `tm.h' should be a link to
+`MACHINE.h'. The header file `config.h' includes `tm.h' and most
+compiler source files include `config.h'. The source file defines a
+variable `targetm', which is a structure containing pointers to
+functions and data relating to the target machine. `MACHINE.c' should
+also contain their definitions, if they are not defined elsewhere in
+GCC, and other functions called through the macros defined in the `.h'
+file.
-C Language Test Suites
-----------------------
+* Menu:
- GCC contains the following C language test suites, in the
-`gcc/testsuite' directory:
+* Target Structure:: The `targetm' variable.
+* Driver:: Controlling how the driver runs the compilation passes.
+* Run-time Target:: Defining `-m' options like `-m68000' and `-m68020'.
+* Per-Function Data:: Defining data structures for per-function information.
+* Storage Layout:: Defining sizes and alignments of data.
+* Type Layout:: Defining sizes and properties of basic user data types.
+* Escape Sequences:: Defining the value of target character escape sequences
+* Registers:: Naming and describing the hardware registers.
+* Register Classes:: Defining the classes of hardware registers.
+* Stack and Calling:: Defining which way the stack grows and by how much.
+* Varargs:: Defining the varargs macros.
+* Trampolines:: Code set up at run time to enter a nested function.
+* Library Calls:: Controlling how library routines are implicitly called.
+* Addressing Modes:: Defining addressing modes valid for memory operands.
+* Condition Code:: Defining how insns update the condition code.
+* Costs:: Defining relative costs of different operations.
+* Scheduling:: Adjusting the behavior of the instruction scheduler.
+* Sections:: Dividing storage into text, data, and other sections.
+* PIC:: Macros for position independent code.
+* Assembler Format:: Defining how to write insns and pseudo-ops to output.
+* Debugging Info:: Defining the format of debugging output.
+* Cross-compilation:: Handling floating point for cross-compilers.
+* Mode Switching:: Insertion of mode-switching instructions.
+* Target Attributes:: Defining target-specific uses of `__attribute__'.
+* Misc:: Everything else.
-`gcc.c-torture/compat'
- FIXME: describe this.
+\1f
+File: gccint.info, Node: Target Structure, Next: Driver, Up: Target Macros
- This directory should probably not be used for new tests.
+10.1 The Global `targetm' Variable
+==================================
-`gcc.c-torture/compile'
- This test suite contains test cases that should compile, but do not
- need to link or run. These test cases are compiled with several
- different combinations of optimization options. All warnings are
- disabled for these test cases, so this directory is not suitable if
- you wish to test for the presence or absence of compiler warnings.
- While special options can be set, and tests disabled on specific
- platforms, by the use of `.x' files, mostly these test cases
- should not contain platform dependencies. FIXME: discuss how
- defines such as `NO_LABEL_VALUES' and `STACK_SIZE' are used.
+ -- Variable: struct gcc_target targetm
+ The target `.c' file must define the global `targetm' variable
+ which contains pointers to functions and data relating to the
+ target machine. The variable is declared in `target.h';
+ `target-def.h' defines the macro `TARGET_INITIALIZER' which is
+ used to initialize the variable, and macros for the default
+ initializers for elements of the structure. The `.c' file should
+ override those macros for which the default definition is
+ inappropriate. For example:
+ #include "target.h"
+ #include "target-def.h"
-`gcc.c-torture/execute'
- This test suite contains test cases that should compile, link and
- run; otherwise the same comments as for `gcc.c-torture/compile'
- apply.
-
-`gcc.c-torture/unsorted'
- FIXME: describe this.
+ /* Initialize the GCC target structure. */
- This directory should probably not be used for new tests.
-
-`gcc.dg'
- This test suite contains tests using the more modern `dg' harness.
- Magic comments determine whether the file is preprocessed,
- compiled, linked or run. In these tests, error and warning
- message texts are compared against expected texts or regular
- expressions given in comments. These tests are run with the
- options `-ansi -pedantic' unless other options are given in the
- test. Except as noted below they are not run with multiple
- optimization options.
+ #undef TARGET_COMP_TYPE_ATTRIBUTES
+ #define TARGET_COMP_TYPE_ATTRIBUTES MACHINE_comp_type_attributes
-`gcc.dg/cpp'
- This subdirectory contains tests of the preprocessor.
+ struct gcc_target targetm = TARGET_INITIALIZER;
-`gcc.dg/debug'
- This subdirectory contains tests for debug formats. Tests in this
- subdirectory are run for each debug format that the compiler
- supports.
+Where a macro should be defined in the `.c' file in this manner to form
+part of the `targetm' structure, it is documented below as a "Target
+Hook" with a prototype. Many macros will change in future from being
+defined in the `.h' file to being part of the `targetm' structure.
-`gcc.dg/format'
- This subdirectory contains tests of the `-Wformat' format
- checking. Tests in this directory are run with and without
- `-DWIDE'.
-
-`gcc.dg/noncompile'
- This subdirectory contains tests of code that should not compile
- and does not need any special compilation options. They are run
- with multiple optimization options, since sometimes invalid code
- crashes the compiler with optimization.
-
-`gcc.dg/special'
- FIXME: describe this.
-
-`gcc.c-torture/misc-tests'
- FIXME: describe this, when it should be used for new tests and
- when it shouldn't.
-
- FIXME: merge in `testsuite/README.gcc' and discuss the format of
-test cases and magic comments more.
-
-\1f
-File: gccint.info, Node: libgcj Tests, Prev: C Tests, Up: Test Suites
-
-The Java library test suites.
------------------------------
-
- Runtime tests are executed via `make check' from the `testsuite'
-directory of the libjava hierarchy in the build tree. Additional
-runtime tests can be checked into this testsuite.
-
- Regression testing of the core packages in libgcj is also covered by
-the Mauve test suite. The Mauve Project develops tests for the Java
-Class Libraries. These tests are run as part of libgcj testing by
-specifying the location of the Mauve tree when invoking `make', as in
-`make MAUVEDIR=~/mauve check'.
-
- The Jacks project provides a test suite for Java compilers that can
-be used to test changes that affect the GCJ front end. There is no
-automated mechanism to run the Jacks suite as part of GCJ testing.
-
- We encourage developers to contribute test cases to Mauve and Jacks.
-
-\1f
-File: gccint.info, Node: Passes, Next: Trees, Prev: Source Tree, Up: Top
-
-Passes and Files of the Compiler
-********************************
-
- The overall control structure of the compiler is in `toplev.c'. This
-file is responsible for initialization, decoding arguments, opening and
-closing files, and sequencing the passes.
-
- The parsing pass is invoked only once, to parse the entire input. A
-high level tree representation is then generated from the input, one
-function at a time. This tree code is then transformed into RTL
-intermediate code, and processed. The files involved in transforming
-the trees into RTL are `expr.c', `expmed.c', and `stmt.c'. The order
-of trees that are processed, is not necessarily the same order they are
-generated from the input, due to deferred inlining, and other
-considerations.
-
- Each time the parsing pass reads a complete function definition or
-top-level declaration, it calls either the function
-`rest_of_compilation', or the function `rest_of_decl_compilation' in
-`toplev.c', which are responsible for all further processing necessary,
-ending with output of the assembler language. All other compiler
-passes run, in sequence, within `rest_of_compilation'. When that
-function returns from compiling a function definition, the storage used
-for that function definition's compilation is entirely freed, unless it
-is an inline function, or was deferred for some reason (this can occur
-in templates, for example). (*note An Inline Function is As Fast As a
-Macro: (gcc)Inline.).
-
- Here is a list of all the passes of the compiler and their source
-files. Also included is a description of where debugging dumps can be
-requested with `-d' options.
-
- * Parsing. This pass reads the entire text of a function definition,
- constructing a high level tree representation. (Because of the
- semantic analysis that takes place during this pass, it does more
- than is formally considered to be parsing.)
-
- The tree representation does not entirely follow C syntax, because
- it is intended to support other languages as well.
-
- Language-specific data type analysis is also done in this pass,
- and every tree node that represents an expression has a data type
- attached. Variables are represented as declaration nodes.
-
- The language-independent source files for parsing are `tree.c',
- `fold-const.c', and `stor-layout.c'. There are also header files
- `tree.h' and `tree.def' which define the format of the tree
- representation.
-
- C preprocessing, for language front ends, that want or require it,
- is performed by cpplib, which is covered in separate
- documentation. In particular, the internals are covered in *Note
- Cpplib internals: (cppinternals)Top.
-
- The source files to parse C are `c-convert.c', `c-decl.c',
- `c-errors.c', `c-lang.c', `c-objc-common.c', `c-parse.in',
- `c-aux-info.c', and `c-typeck.c', along with a header file
- `c-tree.h' and some files shared with Objective-C and C++.
-
- The source files for parsing C++ are in `cp/'. They are `parse.y',
- `class.c', `cvt.c', `decl.c', `decl2.c', `except.c', `expr.c',
- `init.c', `lex.c', `method.c', `ptree.c', `search.c', `spew.c',
- `semantics.c', `tree.c', `typeck2.c', and `typeck.c', along with
- header files `cp-tree.def', `cp-tree.h', and `decl.h'.
-
- The special source files for parsing Objective-C are in `objc/'.
- They are `objc-act.c', `objc-tree.def', and `objc-act.h'. Certain
- C-specific files are used for this as well.
-
- The files `c-common.c', `c-common.def', `c-format.c', `c-pragma.c',
- `c-semantics.c', and `c-lex.c', along with header files
- `c-common.h', `c-dump.h', `c-lex.h', and `c-pragma.h', are also
- used for all of the above languages.
-
- * Tree optimization. This is the optimization of the tree
- representation, before converting into RTL code.
-
- Currently, the main optimization performed here is tree-based
- inlining. This is implemented in `tree-inline.c' and used by both
- C and C++. Note that tree based inlining turns off rtx based
- inlining (since it's more powerful, it would be a waste of time to
- do rtx based inlining in addition).
-
- Constant folding and some arithmetic simplifications are also done
- during this pass, on the tree representation. The routines that
- perform these tasks are located in `fold-const.c'.
-
- * RTL generation. This is the conversion of syntax tree into RTL
- code.
+\1f
+File: gccint.info, Node: Driver, Next: Run-time Target, Prev: Target Structure, Up: Target Macros
+
+10.2 Controlling the Compilation Driver, `gcc'
+==============================================
+
+You can control the compilation driver.
+
+`SWITCH_TAKES_ARG (CHAR)'
+ A C expression which determines whether the option `-CHAR' takes
+ arguments. The value should be the number of arguments that
+ option takes-zero, for many options.
+
+ By default, this macro is defined as `DEFAULT_SWITCH_TAKES_ARG',
+ which handles the standard options properly. You need not define
+ `SWITCH_TAKES_ARG' unless you wish to add additional options which
+ take arguments. Any redefinition should call
+ `DEFAULT_SWITCH_TAKES_ARG' and then check for additional options.
+
+`WORD_SWITCH_TAKES_ARG (NAME)'
+ A C expression which determines whether the option `-NAME' takes
+ arguments. The value should be the number of arguments that
+ option takes-zero, for many options. This macro rather than
+ `SWITCH_TAKES_ARG' is used for multi-character option names.
+
+ By default, this macro is defined as
+ `DEFAULT_WORD_SWITCH_TAKES_ARG', which handles the standard options
+ properly. You need not define `WORD_SWITCH_TAKES_ARG' unless you
+ wish to add additional options which take arguments. Any
+ redefinition should call `DEFAULT_WORD_SWITCH_TAKES_ARG' and then
+ check for additional options.
+
+`SWITCH_CURTAILS_COMPILATION (CHAR)'
+ A C expression which determines whether the option `-CHAR' stops
+ compilation before the generation of an executable. The value is
+ boolean, nonzero if the option does stop an executable from being
+ generated, zero otherwise.
+
+ By default, this macro is defined as
+ `DEFAULT_SWITCH_CURTAILS_COMPILATION', which handles the standard
+ options properly. You need not define
+ `SWITCH_CURTAILS_COMPILATION' unless you wish to add additional
+ options which affect the generation of an executable. Any
+ redefinition should call `DEFAULT_SWITCH_CURTAILS_COMPILATION' and
+ then check for additional options.
+
+`SWITCHES_NEED_SPACES'
+ A string-valued C expression which enumerates the options for which
+ the linker needs a space between the option and its argument.
+
+ If this macro is not defined, the default value is `""'.
+
+`TARGET_OPTION_TRANSLATE_TABLE'
+ If defined, a list of pairs of strings, the first of which is a
+ potential command line target to the `gcc' driver program, and the
+ second of which is a space-separated (tabs and other whitespace
+ are not supported) list of options with which to replace the first
+ option. The target defining this list is responsible for assuring
+ that the results are valid. Replacement options may not be the
+ `--opt' style, they must be the `-opt' style. It is the intention
+ of this macro to provide a mechanism for substitution that affects
+ the multilibs chosen, such as one option that enables many
+ options, some of which select multilibs. Example nonsensical
+ definition, where `-malt-abi', `-EB', and `-mspoo' cause different
+ multilibs to be chosen:
+
+ #define TARGET_OPTION_TRANSLATE_TABLE \
+ { "-fast", "-march=fast-foo -malt-abi -I/usr/fast-foo" }, \
+ { "-compat", "-EB -malign=4 -mspoo" }
+
+`CPP_SPEC'
+ A C string constant that tells the GCC driver program options to
+ pass to CPP. It can also specify how to translate options you
+ give to GCC into options for GCC to pass to the CPP.
+
+ Do not define this macro if it does not need to do anything.
+
+`CPLUSPLUS_CPP_SPEC'
+ This macro is just like `CPP_SPEC', but is used for C++, rather
+ than C. If you do not define this macro, then the value of
+ `CPP_SPEC' (if any) will be used instead.
+
+`NO_BUILTIN_SIZE_TYPE'
+ If this macro is defined, the preprocessor will not define the
+ built-in macro `__SIZE_TYPE__'. The macro `__SIZE_TYPE__' must
+ then be defined by `CPP_SPEC' instead.
+
+ This should be defined if `SIZE_TYPE' depends on target dependent
+ flags which are not accessible to the preprocessor. Otherwise, it
+ should not be defined.
+
+`NO_BUILTIN_PTRDIFF_TYPE'
+ If this macro is defined, the preprocessor will not define the
+ built-in macro `__PTRDIFF_TYPE__'. The macro `__PTRDIFF_TYPE__'
+ must then be defined by `CPP_SPEC' instead.
+
+ This should be defined if `PTRDIFF_TYPE' depends on target
+ dependent flags which are not accessible to the preprocessor.
+ Otherwise, it should not be defined.
+
+`NO_BUILTIN_WCHAR_TYPE'
+ If this macro is defined, the preprocessor will not define the
+ built-in macro `__WCHAR_TYPE__'. The macro `__WCHAR_TYPE__' must
+ then be defined by `CPP_SPEC' instead.
+
+ This should be defined if `WCHAR_TYPE' depends on target dependent
+ flags which are not accessible to the preprocessor. Otherwise, it
+ should not be defined.
+
+`NO_BUILTIN_WINT_TYPE'
+ If this macro is defined, the preprocessor will not define the
+ built-in macro `__WINT_TYPE__'. The macro `__WINT_TYPE__' must
+ then be defined by `CPP_SPEC' instead.
+
+ This should be defined if `WINT_TYPE' depends on target dependent
+ flags which are not accessible to the preprocessor. Otherwise, it
+ should not be defined.
+
+`CC1_SPEC'
+ A C string constant that tells the GCC driver program options to
+ pass to `cc1', `cc1plus', `f771', and the other language front
+ ends. It can also specify how to translate options you give to
+ GCC into options for GCC to pass to front ends.
+
+ Do not define this macro if it does not need to do anything.
+
+`CC1PLUS_SPEC'
+ A C string constant that tells the GCC driver program options to
+ pass to `cc1plus'. It can also specify how to translate options
+ you give to GCC into options for GCC to pass to the `cc1plus'.
+
+ Do not define this macro if it does not need to do anything. Note
+ that everything defined in CC1_SPEC is already passed to `cc1plus'
+ so there is no need to duplicate the contents of CC1_SPEC in
+ CC1PLUS_SPEC.
+
+`ASM_SPEC'
+ A C string constant that tells the GCC driver program options to
+ pass to the assembler. It can also specify how to translate
+ options you give to GCC into options for GCC to pass to the
+ assembler. See the file `sun3.h' for an example of this.
+
+ Do not define this macro if it does not need to do anything.
+
+`ASM_FINAL_SPEC'
+ A C string constant that tells the GCC driver program how to run
+ any programs which cleanup after the normal assembler. Normally,
+ this is not needed. See the file `mips.h' for an example of this.
+
+ Do not define this macro if it does not need to do anything.
+
+`LINK_SPEC'
+ A C string constant that tells the GCC driver program options to
+ pass to the linker. It can also specify how to translate options
+ you give to GCC into options for GCC to pass to the linker.
+
+ Do not define this macro if it does not need to do anything.
+
+`LIB_SPEC'
+ Another C string constant used much like `LINK_SPEC'. The
+ difference between the two is that `LIB_SPEC' is used at the end
+ of the command given to the linker.
+
+ If this macro is not defined, a default is provided that loads the
+ standard C library from the usual place. See `gcc.c'.
+
+`LIBGCC_SPEC'
+ Another C string constant that tells the GCC driver program how
+ and when to place a reference to `libgcc.a' into the linker
+ command line. This constant is placed both before and after the
+ value of `LIB_SPEC'.
+
+ If this macro is not defined, the GCC driver provides a default
+ that passes the string `-lgcc' to the linker.
+
+`STARTFILE_SPEC'
+ Another C string constant used much like `LINK_SPEC'. The
+ difference between the two is that `STARTFILE_SPEC' is used at the
+ very beginning of the command given to the linker.
+
+ If this macro is not defined, a default is provided that loads the
+ standard C startup file from the usual place. See `gcc.c'.
+
+`ENDFILE_SPEC'
+ Another C string constant used much like `LINK_SPEC'. The
+ difference between the two is that `ENDFILE_SPEC' is used at the
+ very end of the command given to the linker.
+
+ Do not define this macro if it does not need to do anything.
+
+`THREAD_MODEL_SPEC'
+ GCC `-v' will print the thread model GCC was configured to use.
+ However, this doesn't work on platforms that are multilibbed on
+ thread models, such as AIX 4.3. On such platforms, define
+ `THREAD_MODEL_SPEC' such that it evaluates to a string without
+ blanks that names one of the recognized thread models. `%*', the
+ default value of this macro, will expand to the value of
+ `thread_file' set in `config.gcc'.
+
+`EXTRA_SPECS'
+ Define this macro to provide additional specifications to put in
+ the `specs' file that can be used in various specifications like
+ `CC1_SPEC'.
+
+ The definition should be an initializer for an array of structures,
+ containing a string constant, that defines the specification name,
+ and a string constant that provides the specification.
+
+ Do not define this macro if it does not need to do anything.
+
+ `EXTRA_SPECS' is useful when an architecture contains several
+ related targets, which have various `..._SPECS' which are similar
+ to each other, and the maintainer would like one central place to
+ keep these definitions.
+
+ For example, the PowerPC System V.4 targets use `EXTRA_SPECS' to
+ define either `_CALL_SYSV' when the System V calling sequence is
+ used or `_CALL_AIX' when the older AIX-based calling sequence is
+ used.
+
+ The `config/rs6000/rs6000.h' target file defines:
+
+ #define EXTRA_SPECS \
+ { "cpp_sysv_default", CPP_SYSV_DEFAULT },
+
+ #define CPP_SYS_DEFAULT ""
+
+ The `config/rs6000/sysv.h' target file defines:
+ #undef CPP_SPEC
+ #define CPP_SPEC \
+ "%{posix: -D_POSIX_SOURCE } \
+ %{mcall-sysv: -D_CALL_SYSV } %{mcall-aix: -D_CALL_AIX } \
+ %{!mcall-sysv: %{!mcall-aix: %(cpp_sysv_default) }} \
+ %{msoft-float: -D_SOFT_FLOAT} %{mcpu=403: -D_SOFT_FLOAT}"
+
+ #undef CPP_SYSV_DEFAULT
+ #define CPP_SYSV_DEFAULT "-D_CALL_SYSV"
+
+ while the `config/rs6000/eabiaix.h' target file defines
+ `CPP_SYSV_DEFAULT' as:
+
+ #undef CPP_SYSV_DEFAULT
+ #define CPP_SYSV_DEFAULT "-D_CALL_AIX"
+
+`LINK_LIBGCC_SPECIAL'
+ Define this macro if the driver program should find the library
+ `libgcc.a' itself and should not pass `-L' options to the linker.
+ If you do not define this macro, the driver program will pass the
+ argument `-lgcc' to tell the linker to do the search and will pass
+ `-L' options to it.
+
+`LINK_LIBGCC_SPECIAL_1'
+ Define this macro if the driver program should find the library
+ `libgcc.a'. If you do not define this macro, the driver program
+ will pass the argument `-lgcc' to tell the linker to do the search.
+ This macro is similar to `LINK_LIBGCC_SPECIAL', except that it does
+ not affect `-L' options.
+
+`LINK_GCC_C_SEQUENCE_SPEC'
+ The sequence in which libgcc and libc are specified to the linker.
+ By default this is `%G %L %G'.
+
+`LINK_COMMAND_SPEC'
+ A C string constant giving the complete command line need to
+ execute the linker. When you do this, you will need to update
+ your port each time a change is made to the link command line
+ within `gcc.c'. Therefore, define this macro only if you need to
+ completely redefine the command line for invoking the linker and
+ there is no other way to accomplish the effect you need.
+ Overriding this macro may be avoidable by overriding
+ `LINK_GCC_C_SEQUENCE_SPEC' instead.
+
+`LINK_ELIMINATE_DUPLICATE_LDIRECTORIES'
+ A nonzero value causes `collect2' to remove duplicate
+ `-LDIRECTORY' search directories from linking commands. Do not
+ give it a nonzero value if removing duplicate search directories
+ changes the linker's semantics.
+
+`MULTILIB_DEFAULTS'
+ Define this macro as a C expression for the initializer of an
+ array of string to tell the driver program which options are
+ defaults for this target and thus do not need to be handled
+ specially when using `MULTILIB_OPTIONS'.
+
+ Do not define this macro if `MULTILIB_OPTIONS' is not defined in
+ the target makefile fragment or if none of the options listed in
+ `MULTILIB_OPTIONS' are set by default. *Note Target Fragment::.
+
+`RELATIVE_PREFIX_NOT_LINKDIR'
+ Define this macro to tell `gcc' that it should only translate a
+ `-B' prefix into a `-L' linker option if the prefix indicates an
+ absolute file name.
+
+`STANDARD_EXEC_PREFIX'
+ Define this macro as a C string constant if you wish to override
+ the standard choice of `/usr/local/lib/gcc-lib/' as the default
+ prefix to try when searching for the executable files of the
+ compiler.
+
+`MD_EXEC_PREFIX'
+ If defined, this macro is an additional prefix to try after
+ `STANDARD_EXEC_PREFIX'. `MD_EXEC_PREFIX' is not searched when the
+ `-b' option is used, or the compiler is built as a cross compiler.
+ If you define `MD_EXEC_PREFIX', then be sure to add it to the list
+ of directories used to find the assembler in `configure.in'.
+
+`STANDARD_STARTFILE_PREFIX'
+ Define this macro as a C string constant if you wish to override
+ the standard choice of `/usr/local/lib/' as the default prefix to
+ try when searching for startup files such as `crt0.o'.
+
+`MD_STARTFILE_PREFIX'
+ If defined, this macro supplies an additional prefix to try after
+ the standard prefixes. `MD_EXEC_PREFIX' is not searched when the
+ `-b' option is used, or when the compiler is built as a cross
+ compiler.
+
+`MD_STARTFILE_PREFIX_1'
+ If defined, this macro supplies yet another prefix to try after the
+ standard prefixes. It is not searched when the `-b' option is
+ used, or when the compiler is built as a cross compiler.
+
+`INIT_ENVIRONMENT'
+ Define this macro as a C string constant if you wish to set
+ environment variables for programs called by the driver, such as
+ the assembler and loader. The driver passes the value of this
+ macro to `putenv' to initialize the necessary environment
+ variables.
+
+`LOCAL_INCLUDE_DIR'
+ Define this macro as a C string constant if you wish to override
+ the standard choice of `/usr/local/include' as the default prefix
+ to try when searching for local header files. `LOCAL_INCLUDE_DIR'
+ comes before `SYSTEM_INCLUDE_DIR' in the search order.
+
+ Cross compilers do not search either `/usr/local/include' or its
+ replacement.
+
+`MODIFY_TARGET_NAME'
+ Define this macro if you with to define command-line switches that
+ modify the default target name
+
+ For each switch, you can include a string to be appended to the
+ first part of the configuration name or a string to be deleted
+ from the configuration name, if present. The definition should be
+ an initializer for an array of structures. Each array element
+ should have three elements: the switch name (a string constant,
+ including the initial dash), one of the enumeration codes `ADD' or
+ `DELETE' to indicate whether the string should be inserted or
+ deleted, and the string to be inserted or deleted (a string
+ constant).
+
+ For example, on a machine where `64' at the end of the
+ configuration name denotes a 64-bit target and you want the `-32'
+ and `-64' switches to select between 32- and 64-bit targets, you
+ would code
+
+ #define MODIFY_TARGET_NAME \
+ { { "-32", DELETE, "64"}, \
+ {"-64", ADD, "64"}}
+
+`SYSTEM_INCLUDE_DIR'
+ Define this macro as a C string constant if you wish to specify a
+ system-specific directory to search for header files before the
+ standard directory. `SYSTEM_INCLUDE_DIR' comes before
+ `STANDARD_INCLUDE_DIR' in the search order.
+
+ Cross compilers do not use this macro and do not search the
+ directory specified.
+
+`STANDARD_INCLUDE_DIR'
+ Define this macro as a C string constant if you wish to override
+ the standard choice of `/usr/include' as the default prefix to try
+ when searching for header files.
+
+ Cross compilers do not use this macro and do not search either
+ `/usr/include' or its replacement.
+
+`STANDARD_INCLUDE_COMPONENT'
+ The "component" corresponding to `STANDARD_INCLUDE_DIR'. See
+ `INCLUDE_DEFAULTS', below, for the description of components. If
+ you do not define this macro, no component is used.
+
+`INCLUDE_DEFAULTS'
+ Define this macro if you wish to override the entire default
+ search path for include files. For a native compiler, the default
+ search path usually consists of `GCC_INCLUDE_DIR',
+ `LOCAL_INCLUDE_DIR', `SYSTEM_INCLUDE_DIR',
+ `GPLUSPLUS_INCLUDE_DIR', and `STANDARD_INCLUDE_DIR'. In addition,
+ `GPLUSPLUS_INCLUDE_DIR' and `GCC_INCLUDE_DIR' are defined
+ automatically by `Makefile', and specify private search areas for
+ GCC. The directory `GPLUSPLUS_INCLUDE_DIR' is used only for C++
+ programs.
+
+ The definition should be an initializer for an array of structures.
+ Each array element should have four elements: the directory name (a
+ string constant), the component name (also a string constant), a
+ flag for C++-only directories, and a flag showing that the
+ includes in the directory don't need to be wrapped in `extern `C''
+ when compiling C++. Mark the end of the array with a null element.
+
+ The component name denotes what GNU package the include file is
+ part of, if any, in all upper-case letters. For example, it might
+ be `GCC' or `BINUTILS'. If the package is part of a
+ vendor-supplied operating system, code the component name as `0'.
+
+ For example, here is the definition used for VAX/VMS:
+
+ #define INCLUDE_DEFAULTS \
+ { \
+ { "GNU_GXX_INCLUDE:", "G++", 1, 1}, \
+ { "GNU_CC_INCLUDE:", "GCC", 0, 0}, \
+ { "SYS$SYSROOT:[SYSLIB.]", 0, 0, 0}, \
+ { ".", 0, 0, 0}, \
+ { 0, 0, 0, 0} \
+ }
- This is where the bulk of target-parameter-dependent code is found,
- since often it is necessary for strategies to apply only when
- certain standard kinds of instructions are available. The purpose
- of named instruction patterns is to provide this information to
- the RTL generation pass.
-
- Optimization is done in this pass for `if'-conditions that are
- comparisons, boolean operations or conditional expressions. Tail
- recursion is detected at this time also. Decisions are made about
- how best to arrange loops and how to output `switch' statements.
-
- The source files for RTL generation include `stmt.c', `calls.c',
- `expr.c', `explow.c', `expmed.c', `function.c', `optabs.c' and
- `emit-rtl.c'. Also, the file `insn-emit.c', generated from the
- machine description by the program `genemit', is used in this
- pass. The header file `expr.h' is used for communication within
- this pass.
-
- The header files `insn-flags.h' and `insn-codes.h', generated from
- the machine description by the programs `genflags' and `gencodes',
- tell this pass which standard names are available for use and
- which patterns correspond to them.
-
- Aside from debugging information output, none of the following
- passes refers to the tree structure representation of the function
- (only part of which is saved).
-
- The decision of whether the function can and should be expanded
- inline in its subsequent callers is made at the end of rtl
- generation. The function must meet certain criteria, currently
- related to the size of the function and the types and number of
- parameters it has. Note that this function may contain loops,
- recursive calls to itself (tail-recursive functions can be
- inlined!), gotos, in short, all constructs supported by GCC. The
- file `integrate.c' contains the code to save a function's rtl for
- later inlining and to inline that rtl when the function is called.
- The header file `integrate.h' is also used for this purpose.
-
- The option `-dr' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.rtl' to
- the input file name.
-
- * Sibiling call optimization. This pass performs tail recursion
- elimination, and tail and sibling call optimizations. The purpose
- of these optimizations is to reduce the overhead of function calls,
- whenever possible.
-
- The source file of this pass is `sibcall.c'
-
- The option `-di' causes a debugging dump of the RTL code after
- this pass is run. This dump file's name is made by appending
- `.sibling' to the input file name.
-
- * Jump optimization. This pass simplifies jumps to the following
- instruction, jumps across jumps, and jumps to jumps. It deletes
- unreferenced labels and unreachable code, except that unreachable
- code that contains a loop is not recognized as unreachable in this
- pass. (Such loops are deleted later in the basic block analysis.)
- It also converts some code originally written with jumps into
- sequences of instructions that directly set values from the
- results of comparisons, if the machine has such instructions.
-
- Jump optimization is performed two or three times. The first time
- is immediately following RTL generation. The second time is after
- CSE, but only if CSE says repeated jump optimization is needed.
- The last time is right before the final pass. That time,
- cross-jumping and deletion of no-op move instructions are done
- together with the optimizations described above.
-
- The source file of this pass is `jump.c'.
-
- The option `-dj' causes a debugging dump of the RTL code after
- this pass is run for the first time. This dump file's name is
- made by appending `.jump' to the input file name.
-
- * Register scan. This pass finds the first and last use of each
- register, as a guide for common subexpression elimination. Its
- source is in `regclass.c'.
-
- * Jump threading. This pass detects a condition jump that branches
- to an identical or inverse test. Such jumps can be `threaded'
- through the second conditional test. The source code for this
- pass is in `jump.c'. This optimization is only performed if
- `-fthread-jumps' is enabled.
-
- * Static Single Assignment (SSA) based optimization passes. The SSA
- conversion passes (to/from) are turned on by the `-fssa' option
- (it is also done automatically if you enable an SSA optimization
- pass). These passes utilize a form called Static Single
- Assignment. In SSA form, each variable (pseudo register) is only
- set once, giving you def-use and use-def chains for free, and
- enabling a lot more optimization passes to be run in linear time.
- Conversion to and from SSA form is handled by functions in `ssa.c'.
-
- The option `-de' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.ssa' to
- the input file name.
- * SSA Conditional Constant Propagation. Turned on by the
- `-fssa-ccp' option. This pass performs conditional constant
- propagation to simplify instructions including conditional
- branches. This pass is more aggressive than the constant
- propagation done by the CSE and GCSE passes, but operates in
- linear time.
-
- The option `-dW' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending
- `.ssaccp' to the input file name.
-
- * SSA Aggressive Dead Code Elimination. Turned on by the
- `-fssa-dce' option. This pass performs elimination of code
- considered unnecessary because it has no externally visible
- effects on the program. It operates in linear time.
-
- The option `-dX' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending
- `.ssadce' to the input file name.
-
- * Common subexpression elimination. This pass also does constant
- propagation. Its source files are `cse.c', and `cselib.c'. If
- constant propagation causes conditional jumps to become
- unconditional or to become no-ops, jump optimization is run again
- when CSE is finished.
-
- The option `-ds' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.cse' to
- the input file name.
-
- * Global common subexpression elimination. This pass performs two
- different types of GCSE depending on whether you are optimizing
- for size or not (LCM based GCSE tends to increase code size for a
- gain in speed, while Morel-Renvoise based GCSE does not). When
- optimizing for size, GCSE is done using Morel-Renvoise Partial
- Redundancy Elimination, with the exception that it does not try to
- move invariants out of loops--that is left to the loop
- optimization pass. If MR PRE GCSE is done, code hoisting (aka
- unification) is also done, as well as load motion. If you are
- optimizing for speed, LCM (lazy code motion) based GCSE is done.
- LCM is based on the work of Knoop, Ruthing, and Steffen. LCM
- based GCSE also does loop invariant code motion. We also perform
- load and store motion when optimizing for speed. Regardless of
- which type of GCSE is used, the GCSE pass also performs global
- constant and copy propagation.
-
- The source file for this pass is `gcse.c', and the LCM routines
- are in `lcm.c'.
-
- The option `-dG' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.gcse' to
- the input file name.
-
- * Loop optimization. This pass moves constant expressions out of
- loops, and optionally does strength-reduction and loop unrolling
- as well. Its source files are `loop.c' and `unroll.c', plus the
- header `loop.h' used for communication between them. Loop
- unrolling uses some functions in `integrate.c' and the header
- `integrate.h'. Loop dependency analysis routines are contained in
- `dependence.c'.
-
- The option `-dL' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.loop' to
- the input file name.
-
- * If `-frerun-cse-after-loop' was enabled, a second common
- subexpression elimination pass is performed after the loop
- optimization pass. Jump threading is also done again at this time
- if it was specified.
-
- The option `-dt' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.cse2' to
- the input file name.
-
- * Data flow analysis (`flow.c'). This pass divides the program into
- basic blocks (and in the process deletes unreachable loops); then
- it computes which pseudo-registers are live at each point in the
- program, and makes the first instruction that uses a value point at
- the instruction that computed the value.
-
- This pass also deletes computations whose results are never used,
- and combines memory references with add or subtract instructions
- to make autoincrement or autodecrement addressing.
-
- The option `-df' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.flow' to
- the input file name. If stupid register allocation is in use, this
- dump file reflects the full results of such allocation.
-
- * Instruction combination (`combine.c'). This pass attempts to
- combine groups of two or three instructions that are related by
- data flow into single instructions. It combines the RTL
- expressions for the instructions by substitution, simplifies the
- result using algebra, and then attempts to match the result
- against the machine description.
-
- The option `-dc' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.combine'
- to the input file name.
-
- * If-conversion is a transformation that transforms control
- dependencies into data dependencies (IE it transforms conditional
- code into a single control stream). It is implemented in the file
- `ifcvt.c'.
-
- The option `-dE' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.ce' to
- the input file name.
-
- * Register movement (`regmove.c'). This pass looks for cases where
- matching constraints would force an instruction to need a reload,
- and this reload would be a register-to-register move. It then
- attempts to change the registers used by the instruction to avoid
- the move instruction.
-
- The option `-dN' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.regmove'
- to the input file name.
-
- * Instruction scheduling (`sched.c'). This pass looks for
- instructions whose output will not be available by the time that
- it is used in subsequent instructions. (Memory loads and floating
- point instructions often have this behavior on RISC machines). It
- re-orders instructions within a basic block to try to separate the
- definition and use of items that otherwise would cause pipeline
- stalls.
-
- Instruction scheduling is performed twice. The first time is
- immediately after instruction combination and the second is
- immediately after reload.
-
- The option `-dS' causes a debugging dump of the RTL code after this
- pass is run for the first time. The dump file's name is made by
- appending `.sched' to the input file name.
-
- * Register class preferencing. The RTL code is scanned to find out
- which register class is best for each pseudo register. The source
- file is `regclass.c'.
-
- * Local register allocation (`local-alloc.c'). This pass allocates
- hard registers to pseudo registers that are used only within one
- basic block. Because the basic block is linear, it can use fast
- and powerful techniques to do a very good job.
-
- The option `-dl' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.lreg' to
- the input file name.
-
- * Global register allocation (`global.c'). This pass allocates hard
- registers for the remaining pseudo registers (those whose life
- spans are not contained in one basic block).
-
- * Reloading. This pass renumbers pseudo registers with the hardware
- registers numbers they were allocated. Pseudo registers that did
- not get hard registers are replaced with stack slots. Then it
- finds instructions that are invalid because a value has failed to
- end up in a register, or has ended up in a register of the wrong
- kind. It fixes up these instructions by reloading the
- problematical values temporarily into registers. Additional
- instructions are generated to do the copying.
-
- The reload pass also optionally eliminates the frame pointer and
- inserts instructions to save and restore call-clobbered registers
- around calls.
-
- Source files are `reload.c' and `reload1.c', plus the header
- `reload.h' used for communication between them.
-
- The option `-dg' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.greg' to
- the input file name.
-
- * Instruction scheduling is repeated here to try to avoid pipeline
- stalls due to memory loads generated for spilled pseudo registers.
-
- The option `-dR' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.sched2'
- to the input file name.
-
- * Basic block reordering. This pass implements profile guided code
- positioning. If profile information is not available, various
- types of static analysis are performed to make the predictions
- normally coming from the profile feedback (IE execution frequency,
- branch probability, etc). It is implemented in the file
- `bb-reorder.c', and the various prediction routines are in
- `predict.c'.
-
- The option `-dB' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.bbro' to
- the input file name.
-
- * Delayed branch scheduling. This optional pass attempts to find
- instructions that can go into the delay slots of other
- instructions, usually jumps and calls. The source file name is
- `reorg.c'.
-
- The option `-dd' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.dbr' to
- the input file name.
-
- * Branch shortening. On many RISC machines, branch instructions
- have a limited range. Thus, longer sequences of instructions must
- be used for long branches. In this pass, the compiler figures out
- what how far each instruction will be from each other instruction,
- and therefore whether the usual instructions, or the longer
- sequences, must be used for each branch.
-
- * Conversion from usage of some hard registers to usage of a register
- stack may be done at this point. Currently, this is supported only
- for the floating-point registers of the Intel 80387 coprocessor.
- The source file name is `reg-stack.c'.
-
- The options `-dk' causes a debugging dump of the RTL code after
- this pass. This dump file's name is made by appending `.stack' to
- the input file name.
-
- * Final. This pass outputs the assembler code for the function. It
- is also responsible for identifying spurious test and compare
- instructions. Machine-specific peephole optimizations are
- performed at the same time. The function entry and exit sequences
- are generated directly as assembler code in this pass; they never
- exist as RTL.
-
- The source files are `final.c' plus `insn-output.c'; the latter is
- generated automatically from the machine description by the tool
- `genoutput'. The header file `conditions.h' is used for
- communication between these files.
-
- * Debugging information output. This is run after final because it
- must output the stack slot offsets for pseudo registers that did
- not get hard registers. Source files are `dbxout.c' for DBX
- symbol table format, `sdbout.c' for SDB symbol table format,
- `dwarfout.c' for DWARF symbol table format, files `dwarf2out.c' and
- `dwarf2asm.c' for DWARF2 symbol table format, and `vmsdbgout.c'
- for VMS debug symbol table format.
-
- Some additional files are used by all or many passes:
-
- * Every pass uses `machmode.def' and `machmode.h' which define the
- machine modes.
-
- * Several passes use `real.h', which defines the default
- representation of floating point constants and how to operate on
+ Here is the order of prefixes tried for exec files:
+
+ 1. Any prefixes specified by the user with `-B'.
+
+ 2. The environment variable `GCC_EXEC_PREFIX', if any.
+
+ 3. The directories specified by the environment variable
+ `COMPILER_PATH'.
+
+ 4. The macro `STANDARD_EXEC_PREFIX'.
+
+ 5. `/usr/lib/gcc/'.
+
+ 6. The macro `MD_EXEC_PREFIX', if any.
+
+ Here is the order of prefixes tried for startfiles:
+
+ 1. Any prefixes specified by the user with `-B'.
+
+ 2. The environment variable `GCC_EXEC_PREFIX', if any.
+
+ 3. The directories specified by the environment variable
+ `LIBRARY_PATH' (or port-specific name; native only, cross
+ compilers do not use this).
+
+ 4. The macro `STANDARD_EXEC_PREFIX'.
+
+ 5. `/usr/lib/gcc/'.
+
+ 6. The macro `MD_EXEC_PREFIX', if any.
+
+ 7. The macro `MD_STARTFILE_PREFIX', if any.
+
+ 8. The macro `STANDARD_STARTFILE_PREFIX'.
+
+ 9. `/lib/'.
+
+ 10. `/usr/lib/'.
+
+\1f
+File: gccint.info, Node: Run-time Target, Next: Per-Function Data, Prev: Driver, Up: Target Macros
+
+10.3 Run-time Target Specification
+==================================
+
+Here are run-time target specifications.
+
+`CPP_PREDEFINES'
+ Define this to be a string constant containing `-D' options to
+ define the predefined macros that identify this machine and system.
+ These macros will be predefined unless the `-ansi' option (or a
+ `-std' option for strict ISO C conformance) is specified.
+
+ In addition, a parallel set of macros are predefined, whose names
+ are made by appending `__' at the beginning and at the end. These
+ `__' macros are permitted by the ISO standard, so they are
+ predefined regardless of whether `-ansi' or a `-std' option is
+ specified.
+
+ For example, on the Sun, one can use the following value:
+
+ "-Dmc68000 -Dsun -Dunix"
+
+ The result is to define the macros `__mc68000__', `__sun__' and
+ `__unix__' unconditionally, and the macros `mc68000', `sun' and
+ `unix' provided `-ansi' is not specified.
+
+`extern int target_flags;'
+ This declaration should be present.
+
+`TARGET_...'
+ This series of macros is to allow compiler command arguments to
+ enable or disable the use of optional features of the target
+ machine. For example, one machine description serves both the
+ 68000 and the 68020; a command argument tells the compiler whether
+ it should use 68020-only instructions or not. This command
+ argument works by means of a macro `TARGET_68020' that tests a bit
+ in `target_flags'.
+
+ Define a macro `TARGET_FEATURENAME' for each such option. Its
+ definition should test a bit in `target_flags'. It is recommended
+ that a helper macro `TARGET_MASK_FEATURENAME' is defined for each
+ bit-value to test, and used in `TARGET_FEATURENAME' and
+ `TARGET_SWITCHES'. For example:
+
+ #define TARGET_MASK_68020 1
+ #define TARGET_68020 (target_flags & TARGET_MASK_68020)
+
+ One place where these macros are used is in the
+ condition-expressions of instruction patterns. Note how
+ `TARGET_68020' appears frequently in the 68000 machine description
+ file, `m68k.md'. Another place they are used is in the
+ definitions of the other macros in the `MACHINE.h' file.
+
+`TARGET_SWITCHES'
+ This macro defines names of command options to set and clear bits
+ in `target_flags'. Its definition is an initializer with a
+ subgrouping for each command option.
+
+ Each subgrouping contains a string constant, that defines the
+ option name, a number, which contains the bits to set in
+ `target_flags', and a second string which is the description
+ displayed by `--help'. If the number is negative then the bits
+ specified by the number are cleared instead of being set. If the
+ description string is present but empty, then no help information
+ will be displayed for that option, but it will not count as an
+ undocumented option. The actual option name is made by appending
+ `-m' to the specified name. Non-empty description strings should
+ be marked with `N_(...)' for `xgettext'. Please do not mark empty
+ strings because the empty string is reserved by GNU gettext.
+ `gettext("")' returns the header entry of the message catalog with
+ meta information, not the empty string.
+
+ In addition to the description for `--help', more detailed
+ documentation for each option should be added to `invoke.texi'.
+
+ One of the subgroupings should have a null string. The number in
+ this grouping is the default value for `target_flags'. Any target
+ options act starting with that value.
+
+ Here is an example which defines `-m68000' and `-m68020' with
+ opposite meanings, and picks the latter as the default:
+
+ #define TARGET_SWITCHES \
+ { { "68020", TARGET_MASK_68020, "" }, \
+ { "68000", -TARGET_MASK_68020, \
+ N_("Compile for the 68000") }, \
+ { "", TARGET_MASK_68020, "" }}
+
+`TARGET_OPTIONS'
+ This macro is similar to `TARGET_SWITCHES' but defines names of
+ command options that have values. Its definition is an
+ initializer with a subgrouping for each command option.
+
+ Each subgrouping contains a string constant, that defines the
+ fixed part of the option name, the address of a variable, and a
+ description string. Non-empty description strings should be
+ marked with `N_(...)' for `xgettext'. Please do not mark empty
+ strings because the empty string is reserved by GNU gettext.
+ `gettext("")' returns the header entry of the message catalog with
+ meta information, not the empty string.
+
+ The variable, type `char *', is set to the variable part of the
+ given option if the fixed part matches. The actual option name is
+ made by appending `-m' to the specified name. Again, each option
+ should also be documented in `invoke.texi'.
+
+ Here is an example which defines `-mshort-data-NUMBER'. If the
+ given option is `-mshort-data-512', the variable `m88k_short_data'
+ will be set to the string `"512"'.
+
+ extern char *m88k_short_data;
+ #define TARGET_OPTIONS \
+ { { "short-data-", &m88k_short_data, \
+ N_("Specify the size of the short data section") } }
+
+`TARGET_VERSION'
+ This macro is a C statement to print on `stderr' a string
+ describing the particular machine description choice. Every
+ machine description should define `TARGET_VERSION'. For example:
+
+ #ifdef MOTOROLA
+ #define TARGET_VERSION \
+ fprintf (stderr, " (68k, Motorola syntax)");
+ #else
+ #define TARGET_VERSION \
+ fprintf (stderr, " (68k, MIT syntax)");
+ #endif
+
+`OVERRIDE_OPTIONS'
+ Sometimes certain combinations of command options do not make
+ sense on a particular target machine. You can define a macro
+ `OVERRIDE_OPTIONS' to take account of this. This macro, if
+ defined, is executed once just after all the command options have
+ been parsed.
+
+ Don't use this macro to turn on various extra optimizations for
+ `-O'. That is what `OPTIMIZATION_OPTIONS' is for.
+
+`OPTIMIZATION_OPTIONS (LEVEL, SIZE)'
+ Some machines may desire to change what optimizations are
+ performed for various optimization levels. This macro, if
+ defined, is executed once just after the optimization level is
+ determined and before the remainder of the command options have
+ been parsed. Values set in this macro are used as the default
+ values for the other command line options.
+
+ LEVEL is the optimization level specified; 2 if `-O2' is
+ specified, 1 if `-O' is specified, and 0 if neither is specified.
+
+ SIZE is nonzero if `-Os' is specified and zero otherwise.
+
+ You should not use this macro to change options that are not
+ machine-specific. These should uniformly selected by the same
+ optimization level on all supported machines. Use this macro to
+ enable machine-specific optimizations.
+
+ *Do not examine `write_symbols' in this macro!* The debugging
+ options are not supposed to alter the generated code.
+
+`CAN_DEBUG_WITHOUT_FP'
+ Define this macro if debugging can be performed even without a
+ frame pointer. If this macro is defined, GCC will turn on the
+ `-fomit-frame-pointer' option whenever `-O' is specified.
+
+\1f
+File: gccint.info, Node: Per-Function Data, Next: Storage Layout, Prev: Run-time Target, Up: Target Macros
+
+10.4 Defining data structures for per-function information.
+===========================================================
+
+If the target needs to store information on a per-function basis, GCC
+provides a macro and a couple of variables to allow this. Note, just
+using statics to store the information is a bad idea, since GCC supports
+nested functions, so you can be halfway through encoding one function
+when another one comes along.
+
+ GCC defines a data structure called `struct function' which contains
+all of the data specific to an individual function. This structure
+contains a field called `machine' whose type is `struct
+machine_function *', which can be used by targets to point to their own
+specific data.
+
+ If a target needs per-function specific data it should define the
+type `struct machine_function' and also the macro `INIT_EXPANDERS'.
+This macro should be used to initialize some or all of the function
+pointers `init_machine_status', `free_machine_status' and
+`mark_machine_status'. These pointers are explained below.
+
+ One typical use of per-function, target specific data is to create an
+RTX to hold the register containing the function's return address. This
+RTX can then be used to implement the `__builtin_return_address'
+function, for level 0.
+
+ Note--earlier implementations of GCC used a single data area to hold
+all of the per-function information. Thus when processing of a nested
+function began the old per-function data had to be pushed onto a stack,
+and when the processing was finished, it had to be popped off the
+stack. GCC used to provide function pointers called
+`save_machine_status' and `restore_machine_status' to handle the saving
+and restoring of the target specific information. Since the single
+data area approach is no longer used, these pointers are no longer
+supported.
+
+ The macro and function pointers are described below.
+
+`INIT_EXPANDERS'
+ Macro called to initialize any target specific information. This
+ macro is called once per function, before generation of any RTL
+ has begun. The intention of this macro is to allow the
+ initialization of the function pointers below.
+
+`init_machine_status'
+ This is a `void (*)(struct function *)' function pointer. If this
+ pointer is non-`NULL' it will be called once per function, before
+ function compilation starts, in order to allow the target to
+ perform any target specific initialization of the `struct
+ function' structure. It is intended that this would be used to
+ initialize the `machine' of that structure.
+
+`free_machine_status'
+ This is a `void (*)(struct function *)' function pointer. If this
+ pointer is non-`NULL' it will be called once per function, after
+ the function has been compiled, in order to allow any memory
+ allocated during the `init_machine_status' function call to be
+ freed.
+
+`mark_machine_status'
+ This is a `void (*)(struct function *)' function pointer. If this
+ pointer is non-`NULL' it will be called once per function in order
+ to mark any data items in the `struct machine_function' structure
+ which need garbage collection.
+
+
+\1f
+File: gccint.info, Node: Storage Layout, Next: Type Layout, Prev: Per-Function Data, Up: Target Macros
+
+10.5 Storage Layout
+===================
+
+Note that the definitions of the macros in this table which are sizes or
+alignments measured in bits do not need to be constant. They can be C
+expressions that refer to static variables, such as the `target_flags'.
+*Note Run-time Target::.
+
+`BITS_BIG_ENDIAN'
+ Define this macro to have the value 1 if the most significant bit
+ in a byte has the lowest number; otherwise define it to have the
+ value zero. This means that bit-field instructions count from the
+ most significant bit. If the machine has no bit-field
+ instructions, then this must still be defined, but it doesn't
+ matter which value it is defined to. This macro need not be a
+ constant.
+
+ This macro does not affect the way structure fields are packed into
+ bytes or words; that is controlled by `BYTES_BIG_ENDIAN'.
+
+`BYTES_BIG_ENDIAN'
+ Define this macro to have the value 1 if the most significant byte
+ in a word has the lowest number. This macro need not be a
+ constant.
+
+`WORDS_BIG_ENDIAN'
+ Define this macro to have the value 1 if, in a multiword object,
+ the most significant word has the lowest number. This applies to
+ both memory locations and registers; GCC fundamentally assumes
+ that the order of words in memory is the same as the order in
+ registers. This macro need not be a constant.
+
+`LIBGCC2_WORDS_BIG_ENDIAN'
+ Define this macro if `WORDS_BIG_ENDIAN' is not constant. This
+ must be a constant value with the same meaning as
+ `WORDS_BIG_ENDIAN', which will be used only when compiling
+ `libgcc2.c'. Typically the value will be set based on
+ preprocessor defines.
+
+`FLOAT_WORDS_BIG_ENDIAN'
+ Define this macro to have the value 1 if `DFmode', `XFmode' or
+ `TFmode' floating point numbers are stored in memory with the word
+ containing the sign bit at the lowest address; otherwise define it
+ to have the value 0. This macro need not be a constant.
+
+ You need not define this macro if the ordering is the same as for
+ multi-word integers.
+
+`BITS_PER_UNIT'
+ Define this macro to be the number of bits in an addressable
+ storage unit (byte); normally 8.
+
+`BITS_PER_WORD'
+ Number of bits in a word; normally 32.
+
+`MAX_BITS_PER_WORD'
+ Maximum number of bits in a word. If this is undefined, the
+ default is `BITS_PER_WORD'. Otherwise, it is the constant value
+ that is the largest value that `BITS_PER_WORD' can have at
+ run-time.
+
+`UNITS_PER_WORD'
+ Number of storage units in a word; normally 4.
+
+`MIN_UNITS_PER_WORD'
+ Minimum number of units in a word. If this is undefined, the
+ default is `UNITS_PER_WORD'. Otherwise, it is the constant value
+ that is the smallest value that `UNITS_PER_WORD' can have at
+ run-time.
+
+`POINTER_SIZE'
+ Width of a pointer, in bits. You must specify a value no wider
+ than the width of `Pmode'. If it is not equal to the width of
+ `Pmode', you must define `POINTERS_EXTEND_UNSIGNED'.
+
+`POINTERS_EXTEND_UNSIGNED'
+ A C expression whose value is greater than zero if pointers that
+ need to be extended from being `POINTER_SIZE' bits wide to `Pmode'
+ are to be zero-extended and zero if they are to be sign-extended.
+ If the value is less then zero then there must be an "ptr_extend"
+ instruction that extends a pointer from `POINTER_SIZE' to `Pmode'.
+
+ You need not define this macro if the `POINTER_SIZE' is equal to
+ the width of `Pmode'.
+
+`PROMOTE_MODE (M, UNSIGNEDP, TYPE)'
+ A macro to update M and UNSIGNEDP when an object whose type is
+ TYPE and which has the specified mode and signedness is to be
+ stored in a register. This macro is only called when TYPE is a
+ scalar type.
+
+ On most RISC machines, which only have operations that operate on
+ a full register, define this macro to set M to `word_mode' if M is
+ an integer mode narrower than `BITS_PER_WORD'. In most cases,
+ only integer modes should be widened because wider-precision
+ floating-point operations are usually more expensive than their
+ narrower counterparts.
+
+ For most machines, the macro definition does not change UNSIGNEDP.
+ However, some machines, have instructions that preferentially
+ handle either signed or unsigned quantities of certain modes. For
+ example, on the DEC Alpha, 32-bit loads from memory and 32-bit add
+ instructions sign-extend the result to 64 bits. On such machines,
+ set UNSIGNEDP according to which kind of extension is more
+ efficient.
+
+ Do not define this macro if it would never modify M.
+
+`PROMOTE_FUNCTION_ARGS'
+ Define this macro if the promotion described by `PROMOTE_MODE'
+ should also be done for outgoing function arguments.
+
+`PROMOTE_FUNCTION_RETURN'
+ Define this macro if the promotion described by `PROMOTE_MODE'
+ should also be done for the return value of functions.
+
+ If this macro is defined, `FUNCTION_VALUE' must perform the same
+ promotions done by `PROMOTE_MODE'.
+
+`PROMOTE_FOR_CALL_ONLY'
+ Define this macro if the promotion described by `PROMOTE_MODE'
+ should _only_ be performed for outgoing function arguments or
+ function return values, as specified by `PROMOTE_FUNCTION_ARGS'
+ and `PROMOTE_FUNCTION_RETURN', respectively.
+
+`PARM_BOUNDARY'
+ Normal alignment required for function parameters on the stack, in
+ bits. All stack parameters receive at least this much alignment
+ regardless of data type. On most machines, this is the same as the
+ size of an integer.
+
+`STACK_BOUNDARY'
+ Define this macro to the minimum alignment enforced by hardware
+ for the stack pointer on this machine. The definition is a C
+ expression for the desired alignment (measured in bits). This
+ value is used as a default if `PREFERRED_STACK_BOUNDARY' is not
+ defined. On most machines, this should be the same as
+ `PARM_BOUNDARY'.
+
+`PREFERRED_STACK_BOUNDARY'
+ Define this macro if you wish to preserve a certain alignment for
+ the stack pointer, greater than what the hardware enforces. The
+ definition is a C expression for the desired alignment (measured
+ in bits). This macro must evaluate to a value equal to or larger
+ than `STACK_BOUNDARY'.
+
+`FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN'
+ A C expression that evaluates true if `PREFERRED_STACK_BOUNDARY' is
+ not guaranteed by the runtime and we should emit code to align the
+ stack at the beginning of `main'.
+
+ If `PUSH_ROUNDING' is not defined, the stack will always be aligned
+ to the specified boundary. If `PUSH_ROUNDING' is defined and
+ specifies a less strict alignment than `PREFERRED_STACK_BOUNDARY',
+ the stack may be momentarily unaligned while pushing arguments.
+
+`FUNCTION_BOUNDARY'
+ Alignment required for a function entry point, in bits.
+
+`BIGGEST_ALIGNMENT'
+ Biggest alignment that any data type can require on this machine,
+ in bits.
+
+`MINIMUM_ATOMIC_ALIGNMENT'
+ If defined, the smallest alignment, in bits, that can be given to
+ an object that can be referenced in one operation, without
+ disturbing any nearby object. Normally, this is `BITS_PER_UNIT',
+ but may be larger on machines that don't have byte or half-word
+ store operations.
+
+`BIGGEST_FIELD_ALIGNMENT'
+ Biggest alignment that any structure or union field can require on
+ this machine, in bits. If defined, this overrides
+ `BIGGEST_ALIGNMENT' for structure and union fields only, unless
+ the field alignment has been set by the `__attribute__ ((aligned
+ (N)))' construct.
+
+`ADJUST_FIELD_ALIGN (FIELD, COMPUTED)'
+ An expression for the alignment of a structure field FIELD if the
+ alignment computed in the usual way (including applying of
+ `BIGGEST_ALIGNMENT' and `BIGGEST_FIELD_ALIGNMENT' to the
+ alignment) is COMPUTED. It overrides alignment only if the field
+ alignment has not been set by the `__attribute__ ((aligned (N)))'
+ construct.
+
+`MAX_OFILE_ALIGNMENT'
+ Biggest alignment supported by the object file format of this
+ machine. Use this macro to limit the alignment which can be
+ specified using the `__attribute__ ((aligned (N)))' construct. If
+ not defined, the default value is `BIGGEST_ALIGNMENT'.
+
+`DATA_ALIGNMENT (TYPE, BASIC-ALIGN)'
+ If defined, a C expression to compute the alignment for a variable
+ in the static store. TYPE is the data type, and BASIC-ALIGN is
+ the alignment that the object would ordinarily have. The value of
+ this macro is used instead of that alignment to align the object.
+
+ If this macro is not defined, then BASIC-ALIGN is used.
+
+ One use of this macro is to increase alignment of medium-size data
+ to make it all fit in fewer cache lines. Another is to cause
+ character arrays to be word-aligned so that `strcpy' calls that
+ copy constants to character arrays can be done inline.
+
+`CONSTANT_ALIGNMENT (CONSTANT, BASIC-ALIGN)'
+ If defined, a C expression to compute the alignment given to a
+ constant that is being placed in memory. CONSTANT is the constant
+ and BASIC-ALIGN is the alignment that the object would ordinarily
+ have. The value of this macro is used instead of that alignment to
+ align the object.
+
+ If this macro is not defined, then BASIC-ALIGN is used.
+
+ The typical use of this macro is to increase alignment for string
+ constants to be word aligned so that `strcpy' calls that copy
+ constants can be done inline.
+
+`LOCAL_ALIGNMENT (TYPE, BASIC-ALIGN)'
+ If defined, a C expression to compute the alignment for a variable
+ in the local store. TYPE is the data type, and BASIC-ALIGN is the
+ alignment that the object would ordinarily have. The value of this
+ macro is used instead of that alignment to align the object.
+
+ If this macro is not defined, then BASIC-ALIGN is used.
+
+ One use of this macro is to increase alignment of medium-size data
+ to make it all fit in fewer cache lines.
+
+`EMPTY_FIELD_BOUNDARY'
+ Alignment in bits to be given to a structure bit-field that
+ follows an empty field such as `int : 0;'.
+
+ Note that `PCC_BITFIELD_TYPE_MATTERS' also affects the alignment
+ that results from an empty field.
+
+`STRUCTURE_SIZE_BOUNDARY'
+ Number of bits which any structure or union's size must be a
+ multiple of. Each structure or union's size is rounded up to a
+ multiple of this.
+
+ If you do not define this macro, the default is the same as
+ `BITS_PER_UNIT'.
+
+`STRICT_ALIGNMENT'
+ Define this macro to be the value 1 if instructions will fail to
+ work if given data not on the nominal alignment. If instructions
+ will merely go slower in that case, define this macro as 0.
+
+`PCC_BITFIELD_TYPE_MATTERS'
+ Define this if you wish to imitate the way many other C compilers
+ handle alignment of bit-fields and the structures that contain
them.
- * All the passes that work with RTL use the header files `rtl.h' and
- `rtl.def', and subroutines in file `rtl.c'. The tools `gen*' also
- use these files to read and work with the machine description RTL.
-
- * All the tools that read the machine description use support
- routines found in `gensupport.c', `errors.c', and `read-rtl.c'.
-
- * Several passes refer to the header file `insn-config.h' which
- contains a few parameters (C macro definitions) generated
- automatically from the machine description RTL by the tool
- `genconfig'.
-
- * Several passes use the instruction recognizer, which consists of
- `recog.c' and `recog.h', plus the files `insn-recog.c' and
- `insn-extract.c' that are generated automatically from the machine
- description by the tools `genrecog' and `genextract'.
-
- * Several passes use the header files `regs.h' which defines the
- information recorded about pseudo register usage, and
- `basic-block.h' which defines the information recorded about basic
- blocks.
-
- * `hard-reg-set.h' defines the type `HARD_REG_SET', a bit-vector
- with a bit for each hard register, and some macros to manipulate
- it. This type is just `int' if the machine has few enough hard
- registers; otherwise it is an array of `int' and some of the
- macros expand into loops.
-
- * Several passes use instruction attributes. A definition of the
- attributes defined for a particular machine is in file
- `insn-attr.h', which is generated from the machine description by
- the program `genattr'. The file `insn-attrtab.c' contains
- subroutines to obtain the attribute values for insns. It is
- generated from the machine description by the program `genattrtab'.
-
-\1f
-File: gccint.info, Node: Trees, Next: RTL, Prev: Passes, Up: Top
-
-Trees: The intermediate representation used by the C and C++ front ends
-***********************************************************************
-
- This chapter documents the internal representation used by GCC to
-represent C and C++ source programs. When presented with a C or C++
-source program, GCC parses the program, performs semantic analysis
-(including the generation of error messages), and then produces the
-internal representation described here. This representation contains a
-complete representation for the entire translation unit provided as
-input to the front end. This representation is then typically processed
-by a code-generator in order to produce machine code, but could also be
-used in the creation of source browsers, intelligent editors, automatic
-documentation generators, interpreters, and any other programs needing
-the ability to process C or C++ code.
-
- This chapter explains the internal representation. In particular, it
-documents the internal representation for C and C++ source constructs,
-and the macros, functions, and variables that can be used to access
-these constructs. The C++ representation is largely a superset of the
-representation used in the C front end. There is only one construct
-used in C that does not appear in the C++ front end and that is the GNU
-"nested function" extension. Many of the macros documented here do not
-apply in C because the corresponding language constructs do not appear
-in C.
-
- If you are developing a "back end", be it is a code-generator or some
-other tool, that uses this representation, you may occasionally find
-that you need to ask questions not easily answered by the functions and
-macros available here. If that situation occurs, it is quite likely
-that GCC already supports the functionality you desire, but that the
-interface is simply not documented here. In that case, you should ask
-the GCC maintainers (via mail to <gcc@gcc.gnu.org>) about documenting
-the functionality you require. Similarly, if you find yourself writing
-functions that do not deal directly with your back end, but instead
-might be useful to other people using the GCC front end, you should
-submit your patches for inclusion in GCC.
+ The behavior is that the type written for a bit-field (`int',
+ `short', or other integer type) imposes an alignment for the
+ entire structure, as if the structure really did contain an
+ ordinary field of that type. In addition, the bit-field is placed
+ within the structure so that it would fit within such a field, not
+ crossing a boundary for it.
+
+ Thus, on most machines, a bit-field whose type is written as `int'
+ would not cross a four-byte boundary, and would force four-byte
+ alignment for the whole structure. (The alignment used may not be
+ four bytes; it is controlled by the other alignment parameters.)
+
+ If the macro is defined, its definition should be a C expression;
+ a nonzero value for the expression enables this behavior.
+
+ Note that if this macro is not defined, or its value is zero, some
+ bit-fields may cross more than one alignment boundary. The
+ compiler can support such references if there are `insv', `extv',
+ and `extzv' insns that can directly reference memory.
+
+ The other known way of making bit-fields work is to define
+ `STRUCTURE_SIZE_BOUNDARY' as large as `BIGGEST_ALIGNMENT'. Then
+ every structure can be accessed with fullwords.
+
+ Unless the machine has bit-field instructions or you define
+ `STRUCTURE_SIZE_BOUNDARY' that way, you must define
+ `PCC_BITFIELD_TYPE_MATTERS' to have a nonzero value.
+
+ If your aim is to make GCC use the same conventions for laying out
+ bit-fields as are used by another compiler, here is how to
+ investigate what the other compiler does. Compile and run this
+ program:
+
+ struct foo1
+ {
+ char x;
+ char :0;
+ char y;
+ };
+
+ struct foo2
+ {
+ char x;
+ int :0;
+ char y;
+ };
+
+ main ()
+ {
+ printf ("Size of foo1 is %d\n",
+ sizeof (struct foo1));
+ printf ("Size of foo2 is %d\n",
+ sizeof (struct foo2));
+ exit (0);
+ }
+
+ If this prints 2 and 5, then the compiler's behavior is what you
+ would get from `PCC_BITFIELD_TYPE_MATTERS'.
+
+`BITFIELD_NBYTES_LIMITED'
+ Like `PCC_BITFIELD_TYPE_MATTERS' except that its effect is limited
+ to aligning a bit-field within the structure.
+
+`MEMBER_TYPE_FORCES_BLK (FIELD)'
+ Return 1 if a structure or array containing FIELD should be
+ accessed using `BLKMODE'.
+
+ Normally, this is not needed. See the file `c4x.h' for an example
+ of how to use this macro to prevent a structure having a floating
+ point field from being accessed in an integer mode.
+
+`ROUND_TYPE_SIZE (TYPE, COMPUTED, SPECIFIED)'
+ Define this macro as an expression for the overall size of a type
+ (given by TYPE as a tree node) when the size computed in the usual
+ way is COMPUTED and the alignment is SPECIFIED.
+
+ The default is to round COMPUTED up to a multiple of SPECIFIED.
+
+`ROUND_TYPE_SIZE_UNIT (TYPE, COMPUTED, SPECIFIED)'
+ Similar to `ROUND_TYPE_SIZE', but sizes and alignments are
+ specified in units (bytes). If you define `ROUND_TYPE_SIZE', you
+ must also define this macro and they must be defined consistently
+ with each other.
+
+`ROUND_TYPE_ALIGN (TYPE, COMPUTED, SPECIFIED)'
+ Define this macro as an expression for the alignment of a type
+ (given by TYPE as a tree node) if the alignment computed in the
+ usual way is COMPUTED and the alignment explicitly specified was
+ SPECIFIED.
+
+ The default is to use SPECIFIED if it is larger; otherwise, use
+ the smaller of COMPUTED and `BIGGEST_ALIGNMENT'
+
+`MAX_FIXED_MODE_SIZE'
+ An integer expression for the size in bits of the largest integer
+ machine mode that should actually be used. All integer machine
+ modes of this size or smaller can be used for structures and
+ unions with the appropriate sizes. If this macro is undefined,
+ `GET_MODE_BITSIZE (DImode)' is assumed.
+
+`VECTOR_MODE_SUPPORTED_P(MODE)'
+ Define this macro to be nonzero if the port is prepared to handle
+ insns involving vector mode MODE. At the very least, it must have
+ move patterns for this mode.
+
+`STACK_SAVEAREA_MODE (SAVE_LEVEL)'
+ If defined, an expression of type `enum machine_mode' that
+ specifies the mode of the save area operand of a
+ `save_stack_LEVEL' named pattern (*note Standard Names::).
+ SAVE_LEVEL is one of `SAVE_BLOCK', `SAVE_FUNCTION', or
+ `SAVE_NONLOCAL' and selects which of the three named patterns is
+ having its mode specified.
+
+ You need not define this macro if it always returns `Pmode'. You
+ would most commonly define this macro if the `save_stack_LEVEL'
+ patterns need to support both a 32- and a 64-bit mode.
+
+`STACK_SIZE_MODE'
+ If defined, an expression of type `enum machine_mode' that
+ specifies the mode of the size increment operand of an
+ `allocate_stack' named pattern (*note Standard Names::).
+
+ You need not define this macro if it always returns `word_mode'.
+ You would most commonly define this macro if the `allocate_stack'
+ pattern needs to support both a 32- and a 64-bit mode.
+
+`CHECK_FLOAT_VALUE (MODE, VALUE, OVERFLOW)'
+ A C statement to validate the value VALUE (of type `double') for
+ mode MODE. This means that you check whether VALUE fits within
+ the possible range of values for mode MODE on this target machine.
+ The mode MODE is always a mode of class `MODE_FLOAT'. OVERFLOW is
+ nonzero if the value is already known to be out of range.
+
+ If VALUE is not valid or if OVERFLOW is nonzero, you should set
+ OVERFLOW to 1 and then assign some valid value to VALUE. Allowing
+ an invalid value to go through the compiler can produce incorrect
+ assembler code which may even cause Unix assemblers to crash.
+
+ This macro need not be defined if there is no work for it to do.
+
+`TARGET_FLOAT_FORMAT'
+ A code distinguishing the floating point format of the target
+ machine. There are five defined values:
+
+ `IEEE_FLOAT_FORMAT'
+ This code indicates IEEE floating point. It is the default;
+ there is no need to define this macro when the format is IEEE.
+
+ `VAX_FLOAT_FORMAT'
+ This code indicates the "D float" format used on the VAX.
+
+ `IBM_FLOAT_FORMAT'
+ This code indicates the format used on the IBM System/370.
+
+ `C4X_FLOAT_FORMAT'
+ This code indicates the format used on the TMS320C3x/C4x.
+
+ `UNKNOWN_FLOAT_FORMAT'
+ This code indicates any other format.
+
+ The value of this macro is compared with `HOST_FLOAT_FORMAT', which
+ is defined by the `configure' script, to determine whether the
+ target machine has the same format as the host machine. If any
+ other formats are actually in use on supported machines, new codes
+ should be defined for them.
+
+ The ordering of the component words of floating point values
+ stored in memory is controlled by `FLOAT_WORDS_BIG_ENDIAN'.
+
+
+ -- Target Hook: bool TARGET_MS_BITFIELD_LAYOUT_P (tree RECORD_TYPE)
+ This target hook returns `true' if bit-fields in the given
+ RECORD_TYPE are to be laid out following the rules of Microsoft
+ Visual C/C++, namely: (i) a bit-field won't share the same storage
+ unit with the previous bit-field if their underlying types have
+ different sizes, and the bit-field will be aligned to the highest
+ alignment of the underlying types of itself and of the previous
+ bit-field; (ii) a zero-sized bit-field will affect the alignment of
+ the whole enclosing structure, even if it is unnamed; except that
+ (iii) a zero-sized bit-field will be disregarded unless it follows
+ another bit-field of non-zero size. If this hook returns `true',
+ other macros that control bit-field layout are ignored.
-* Menu:
+\1f
+File: gccint.info, Node: Type Layout, Next: Escape Sequences, Prev: Storage Layout, Up: Target Macros
+
+10.6 Layout of Source Language Data Types
+=========================================
+
+These macros define the sizes and other characteristics of the standard
+basic data types used in programs being compiled. Unlike the macros in
+the previous section, these apply to specific features of C and related
+languages, rather than to fundamental aspects of storage layout.
+
+`INT_TYPE_SIZE'
+ A C expression for the size in bits of the type `int' on the
+ target machine. If you don't define this, the default is one word.
+
+`SHORT_TYPE_SIZE'
+ A C expression for the size in bits of the type `short' on the
+ target machine. If you don't define this, the default is half a
+ word. (If this would be less than one storage unit, it is rounded
+ up to one unit.)
+
+`LONG_TYPE_SIZE'
+ A C expression for the size in bits of the type `long' on the
+ target machine. If you don't define this, the default is one word.
+
+`ADA_LONG_TYPE_SIZE'
+ On some machines, the size used for the Ada equivalent of the type
+ `long' by a native Ada compiler differs from that used by C. In
+ that situation, define this macro to be a C expression to be used
+ for the size of that type. If you don't define this, the default
+ is the value of `LONG_TYPE_SIZE'.
+
+`MAX_LONG_TYPE_SIZE'
+ Maximum number for the size in bits of the type `long' on the
+ target machine. If this is undefined, the default is
+ `LONG_TYPE_SIZE'. Otherwise, it is the constant value that is the
+ largest value that `LONG_TYPE_SIZE' can have at run-time. This is
+ used in `cpp'.
+
+`LONG_LONG_TYPE_SIZE'
+ A C expression for the size in bits of the type `long long' on the
+ target machine. If you don't define this, the default is two
+ words. If you want to support GNU Ada on your machine, the value
+ of this macro must be at least 64.
+
+`CHAR_TYPE_SIZE'
+ A C expression for the size in bits of the type `char' on the
+ target machine. If you don't define this, the default is
+ `BITS_PER_UNIT'.
+
+`MAX_CHAR_TYPE_SIZE'
+ Maximum number for the size in bits of the type `char' on the
+ target machine. If this is undefined, the default is
+ `CHAR_TYPE_SIZE'. Otherwise, it is the constant value that is the
+ largest value that `CHAR_TYPE_SIZE' can have at run-time. This is
+ used in `cpp'.
+
+`BOOL_TYPE_SIZE'
+ A C expression for the size in bits of the C++ type `bool' and C99
+ type `_Bool' on the target machine. If you don't define this, and
+ you probably shouldn't, the default is `CHAR_TYPE_SIZE'.
+
+`FLOAT_TYPE_SIZE'
+ A C expression for the size in bits of the type `float' on the
+ target machine. If you don't define this, the default is one word.
+
+`DOUBLE_TYPE_SIZE'
+ A C expression for the size in bits of the type `double' on the
+ target machine. If you don't define this, the default is two
+ words.
+
+`LONG_DOUBLE_TYPE_SIZE'
+ A C expression for the size in bits of the type `long double' on
+ the target machine. If you don't define this, the default is two
+ words.
+
+ Maximum number for the size in bits of the type `long double' on
+ the target machine. If this is undefined, the default is
+ `LONG_DOUBLE_TYPE_SIZE'. Otherwise, it is the constant value that
+ is the largest value that `LONG_DOUBLE_TYPE_SIZE' can have at
+ run-time. This is used in `cpp'.
+
+ Define this macro to be 1 if the target machine uses 80-bit
+ floating-point values with 128-bit size and alignment. This is
+ used in `real.c'.
+
+`WIDEST_HARDWARE_FP_SIZE'
+ A C expression for the size in bits of the widest floating-point
+ format supported by the hardware. If you define this macro, you
+ must specify a value less than or equal to the value of
+ `LONG_DOUBLE_TYPE_SIZE'. If you do not define this macro, the
+ value of `LONG_DOUBLE_TYPE_SIZE' is the default.
+
+`DEFAULT_SIGNED_CHAR'
+ An expression whose value is 1 or 0, according to whether the type
+ `char' should be signed or unsigned by default. The user can
+ always override this default with the options `-fsigned-char' and
+ `-funsigned-char'.
+
+`DEFAULT_SHORT_ENUMS'
+ A C expression to determine whether to give an `enum' type only as
+ many bytes as it takes to represent the range of possible values
+ of that type. A nonzero value means to do that; a zero value
+ means all `enum' types should be allocated like `int'.
+
+ If you don't define the macro, the default is 0.
+
+`SIZE_TYPE'
+ A C expression for a string describing the name of the data type
+ to use for size values. The typedef name `size_t' is defined
+ using the contents of the string.
+
+ The string can contain more than one keyword. If so, separate
+ them with spaces, and write first any length keyword, then
+ `unsigned' if appropriate, and finally `int'. The string must
+ exactly match one of the data type names defined in the function
+ `init_decl_processing' in the file `c-decl.c'. You may not omit
+ `int' or change the order--that would cause the compiler to crash
+ on startup.
+
+ If you don't define this macro, the default is `"long unsigned
+ int"'.
+
+`PTRDIFF_TYPE'
+ A C expression for a string describing the name of the data type
+ to use for the result of subtracting two pointers. The typedef
+ name `ptrdiff_t' is defined using the contents of the string. See
+ `SIZE_TYPE' above for more information.
+
+ If you don't define this macro, the default is `"long int"'.
+
+`WCHAR_TYPE'
+ A C expression for a string describing the name of the data type
+ to use for wide characters. The typedef name `wchar_t' is defined
+ using the contents of the string. See `SIZE_TYPE' above for more
+ information.
+
+ If you don't define this macro, the default is `"int"'.
+
+`WCHAR_TYPE_SIZE'
+ A C expression for the size in bits of the data type for wide
+ characters. This is used in `cpp', which cannot make use of
+ `WCHAR_TYPE'.
+
+`MAX_WCHAR_TYPE_SIZE'
+ Maximum number for the size in bits of the data type for wide
+ characters. If this is undefined, the default is
+ `WCHAR_TYPE_SIZE'. Otherwise, it is the constant value that is the
+ largest value that `WCHAR_TYPE_SIZE' can have at run-time. This is
+ used in `cpp'.
+
+`GCOV_TYPE_SIZE'
+ A C expression for the size in bits of the type used for gcov
+ counters on the target machine. If you don't define this, the
+ default is one `LONG_TYPE_SIZE' in case it is greater or equal to
+ 64-bit and `LONG_LONG_TYPE_SIZE' otherwise. You may want to
+ re-define the type to ensure atomicity for counters in
+ multithreaded programs.
+
+`WINT_TYPE'
+ A C expression for a string describing the name of the data type to
+ use for wide characters passed to `printf' and returned from
+ `getwc'. The typedef name `wint_t' is defined using the contents
+ of the string. See `SIZE_TYPE' above for more information.
+
+ If you don't define this macro, the default is `"unsigned int"'.
+
+`INTMAX_TYPE'
+ A C expression for a string describing the name of the data type
+ that can represent any value of any standard or extended signed
+ integer type. The typedef name `intmax_t' is defined using the
+ contents of the string. See `SIZE_TYPE' above for more
+ information.
+
+ If you don't define this macro, the default is the first of
+ `"int"', `"long int"', or `"long long int"' that has as much
+ precision as `long long int'.
+
+`UINTMAX_TYPE'
+ A C expression for a string describing the name of the data type
+ that can represent any value of any standard or extended unsigned
+ integer type. The typedef name `uintmax_t' is defined using the
+ contents of the string. See `SIZE_TYPE' above for more
+ information.
+
+ If you don't define this macro, the default is the first of
+ `"unsigned int"', `"long unsigned int"', or `"long long unsigned
+ int"' that has as much precision as `long long unsigned int'.
+
+`TARGET_PTRMEMFUNC_VBIT_LOCATION'
+ The C++ compiler represents a pointer-to-member-function with a
+ struct that looks like:
+
+ struct {
+ union {
+ void (*fn)();
+ ptrdiff_t vtable_index;
+ };
+ ptrdiff_t delta;
+ };
+
+ The C++ compiler must use one bit to indicate whether the function
+ that will be called through a pointer-to-member-function is
+ virtual. Normally, we assume that the low-order bit of a function
+ pointer must always be zero. Then, by ensuring that the
+ vtable_index is odd, we can distinguish which variant of the union
+ is in use. But, on some platforms function pointers can be odd,
+ and so this doesn't work. In that case, we use the low-order bit
+ of the `delta' field, and shift the remainder of the `delta' field
+ to the left.
+
+ GCC will automatically make the right selection about where to
+ store this bit using the `FUNCTION_BOUNDARY' setting for your
+ platform. However, some platforms such as ARM/Thumb have
+ `FUNCTION_BOUNDARY' set such that functions always start at even
+ addresses, but the lowest bit of pointers to functions indicate
+ whether the function at that address is in ARM or Thumb mode. If
+ this is the case of your architecture, you should define this
+ macro to `ptrmemfunc_vbit_in_delta'.
+
+ In general, you should not have to define this macro. On
+ architectures in which function addresses are always even,
+ according to `FUNCTION_BOUNDARY', GCC will automatically define
+ this macro to `ptrmemfunc_vbit_in_pfn'.
+
+`TARGET_VTABLE_USES_DESCRIPTORS'
+ Normally, the C++ compiler uses function pointers in vtables. This
+ macro allows the target to change to use "function descriptors"
+ instead. Function descriptors are found on targets for whom a
+ function pointer is actually a small data structure. Normally the
+ data structure consists of the actual code address plus a data
+ pointer to which the function's data is relative.
+
+ If vtables are used, the value of this macro should be the number
+ of words that the function descriptor occupies.
+
+\1f
+File: gccint.info, Node: Escape Sequences, Next: Registers, Prev: Type Layout, Up: Target Macros
+
+10.7 Target Character Escape Sequences
+======================================
+
+By default, GCC assumes that the C character escape sequences take on
+their ASCII values for the target. If this is not correct, you must
+explicitly define all of the macros below.
-* Deficiencies:: Topics net yet covered in this document.
-* Tree overview:: All about `tree's.
-* Types:: Fundamental and aggregate types.
-* Scopes:: Namespaces and classes.
-* Functions:: Overloading, function bodies, and linkage.
-* Declarations:: Type declarations and variables.
-* Attributes:: Declaration and type attributes.
-* Expression trees:: From `typeid' to `throw'.
-
-\1f
-File: gccint.info, Node: Deficiencies, Next: Tree overview, Up: Trees
-
-Deficiencies
-============
-
- There are many places in which this document is incomplet and
-incorrekt. It is, as of yet, only _preliminary_ documentation.
-
-\1f
-File: gccint.info, Node: Tree overview, Next: Types, Prev: Deficiencies, Up: Trees
-
-Overview
-========
-
- The central data structure used by the internal representation is the
-`tree'. These nodes, while all of the C type `tree', are of many
-varieties. A `tree' is a pointer type, but the object to which it
-points may be of a variety of types. From this point forward, we will
-refer to trees in ordinary type, rather than in `this font', except
-when talking about the actual C type `tree'.
-
- You can tell what kind of node a particular tree is by using the
-`TREE_CODE' macro. Many, many macros take a trees as input and return
-trees as output. However, most macros require a certain kinds of tree
-node as input. In other words, there is a type-system for trees, but
-it is not reflected in the C type-system.
-
- For safety, it is useful to configure GCC with `--enable-checking'.
-Although this results in a significant performance penalty (since all
-tree types are checked at run-time), and is therefore inappropriate in a
-release version, it is extremely helpful during the development process.
-
- Many macros behave as predicates. Many, although not all, of these
-predicates end in `_P'. Do not rely on the result type of these macros
-being of any particular type. You may, however, rely on the fact that
-the type can be compared to `0', so that statements like
- if (TEST_P (t) && !TEST_P (y))
- x = 1;
-
-and
- int i = (TEST_P (t) != 0);
-
-are legal. Macros that return `int' values now may be changed to
-return `tree' values, or other pointers in the future. Even those that
-continue to return `int' may return multiple nonzero codes where
-previously they returned only zero and one. Therefore, you should not
-write code like
- if (TEST_P (t) == 1)
-
-as this code is not guaranteed to work correctly in the future.
-
- You should not take the address of values returned by the macros or
-functions described here. In particular, no guarantee is given that the
-values are lvalues.
-
- In general, the names of macros are all in uppercase, while the
-names of functions are entirely in lower case. There are rare
-exceptions to this rule. You should assume that any macro or function
-whose name is made up entirely of uppercase letters may evaluate its
-arguments more than once. You may assume that a macro or function
-whose name is made up entirely of lowercase letters will evaluate its
-arguments only once.
-
- The `error_mark_node' is a special tree. Its tree code is
-`ERROR_MARK', but since there is only ever one node with that code, the
-usual practice is to compare the tree against `error_mark_node'. (This
-test is just a test for pointer equality.) If an error has occurred
-during front-end processing the flag `errorcount' will be set. If the
-front end has encountered code it cannot handle, it will issue a
-message to the user and set `sorrycount'. When these flags are set,
-any macro or function which normally returns a tree of a particular
-kind may instead return the `error_mark_node'. Thus, if you intend to
-do any processing of erroneous code, you must be prepared to deal with
-the `error_mark_node'.
-
- Occasionally, a particular tree slot (like an operand to an
-expression, or a particular field in a declaration) will be referred to
-as "reserved for the back end." These slots are used to store RTL when
-the tree is converted to RTL for use by the GCC back end. However, if
-that process is not taking place (e.g., if the front end is being hooked
-up to an intelligent editor), then those slots may be used by the back
-end presently in use.
-
- If you encounter situations that do not match this documentation,
-such as tree nodes of types not mentioned here, or macros documented to
-return entities of a particular kind that instead return entities of
-some different kind, you have found a bug, either in the front end or in
-the documentation. Please report these bugs as you would any other bug.
+`TARGET_BELL'
+ A C constant expression for the integer value for escape sequence
+ `\a'.
+
+`TARGET_ESC'
+ A C constant expression for the integer value of the target escape
+ character. As an extension, GCC evaluates the escape sequences
+ `\e' and `\E' to this.
+
+`TARGET_BS'
+`TARGET_TAB'
+`TARGET_NEWLINE'
+ C constant expressions for the integer values for escape sequences
+ `\b', `\t' and `\n'.
+
+`TARGET_VT'
+`TARGET_FF'
+`TARGET_CR'
+ C constant expressions for the integer values for escape sequences
+ `\v', `\f' and `\r'.
+
+\1f
+File: gccint.info, Node: Registers, Next: Register Classes, Prev: Escape Sequences, Up: Target Macros
+
+10.8 Register Usage
+===================
+
+This section explains how to describe what registers the target machine
+has, and how (in general) they can be used.
+
+ The description of which registers a specific instruction can use is
+done with register classes; see *note Register Classes::. For
+information on using registers to access a stack frame, see *note Frame
+Registers::. For passing values in registers, see *note Register
+Arguments::. For returning values in registers, see *note Scalar
+Return::.
* Menu:
-* Macros and Functions::Macros and functions that can be used with all trees.
-* Identifiers:: The names of things.
-* Containers:: Lists and vectors.
+* Register Basics:: Number and kinds of registers.
+* Allocation Order:: Order in which registers are allocated.
+* Values in Registers:: What kinds of values each reg can hold.
+* Leaf Functions:: Renumbering registers for leaf functions.
+* Stack Registers:: Handling a register stack such as 80387.
\1f
-File: gccint.info, Node: Macros and Functions, Next: Identifiers, Up: Tree overview
+File: gccint.info, Node: Register Basics, Next: Allocation Order, Up: Registers
+
+10.8.1 Basic Characteristics of Registers
+-----------------------------------------
+
+Registers have various characteristics.
+
+`FIRST_PSEUDO_REGISTER'
+ Number of hardware registers known to the compiler. They receive
+ numbers 0 through `FIRST_PSEUDO_REGISTER-1'; thus, the first
+ pseudo register's number really is assigned the number
+ `FIRST_PSEUDO_REGISTER'.
+
+`FIXED_REGISTERS'
+ An initializer that says which registers are used for fixed
+ purposes all throughout the compiled code and are therefore not
+ available for general allocation. These would include the stack
+ pointer, the frame pointer (except on machines where that can be
+ used as a general register when no frame pointer is needed), the
+ program counter on machines where that is considered one of the
+ addressable registers, and any other numbered register with a
+ standard use.
+
+ This information is expressed as a sequence of numbers, separated
+ by commas and surrounded by braces. The Nth number is 1 if
+ register N is fixed, 0 otherwise.
+
+ The table initialized from this macro, and the table initialized by
+ the following one, may be overridden at run time either
+ automatically, by the actions of the macro
+ `CONDITIONAL_REGISTER_USAGE', or by the user with the command
+ options `-ffixed-REG', `-fcall-used-REG' and `-fcall-saved-REG'.
+
+`CALL_USED_REGISTERS'
+ Like `FIXED_REGISTERS' but has 1 for each register that is
+ clobbered (in general) by function calls as well as for fixed
+ registers. This macro therefore identifies the registers that are
+ not available for general allocation of values that must live
+ across function calls.
+
+ If a register has 0 in `CALL_USED_REGISTERS', the compiler
+ automatically saves it on function entry and restores it on
+ function exit, if the register is used within the function.
+
+`CALL_REALLY_USED_REGISTERS'
+ Like `CALL_USED_REGISTERS' except this macro doesn't require that
+ the entire set of `FIXED_REGISTERS' be included.
+ (`CALL_USED_REGISTERS' must be a superset of `FIXED_REGISTERS').
+ This macro is optional. If not specified, it defaults to the value
+ of `CALL_USED_REGISTERS'.
+
+`HARD_REGNO_CALL_PART_CLOBBERED (REGNO, MODE)'
+ A C expression that is nonzero if it is not permissible to store a
+ value of mode MODE in hard register number REGNO across a call
+ without some part of it being clobbered. For most machines this
+ macro need not be defined. It is only required for machines that
+ do not preserve the entire contents of a register across a call.
+
+`CONDITIONAL_REGISTER_USAGE'
+ Zero or more C statements that may conditionally modify five
+ variables `fixed_regs', `call_used_regs', `global_regs',
+ `reg_names', and `reg_class_contents', to take into account any
+ dependence of these register sets on target flags. The first three
+ of these are of type `char []' (interpreted as Boolean vectors).
+ `global_regs' is a `const char *[]', and `reg_class_contents' is a
+ `HARD_REG_SET'. Before the macro is called, `fixed_regs',
+ `call_used_regs', `reg_class_contents', and `reg_names' have been
+ initialized from `FIXED_REGISTERS', `CALL_USED_REGISTERS',
+ `REG_CLASS_CONTENTS', and `REGISTER_NAMES', respectively.
+ `global_regs' has been cleared, and any `-ffixed-REG',
+ `-fcall-used-REG' and `-fcall-saved-REG' command options have been
+ applied.
+
+ You need not define this macro if it has no work to do.
+
+ If the usage of an entire class of registers depends on the target
+ flags, you may indicate this to GCC by using this macro to modify
+ `fixed_regs' and `call_used_regs' to 1 for each of the registers
+ in the classes which should not be used by GCC. Also define the
+ macro `REG_CLASS_FROM_LETTER' to return `NO_REGS' if it is called
+ with a letter for a class that shouldn't be used.
+
+ (However, if this class is not included in `GENERAL_REGS' and all
+ of the insn patterns whose constraints permit this class are
+ controlled by target switches, then GCC will automatically avoid
+ using these registers when the target switches are opposed to
+ them.)
+
+`NON_SAVING_SETJMP'
+ If this macro is defined and has a nonzero value, it means that
+ `setjmp' and related functions fail to save the registers, or that
+ `longjmp' fails to restore them. To compensate, the compiler
+ avoids putting variables in registers in functions that use
+ `setjmp'.
+
+`INCOMING_REGNO (OUT)'
+ Define this macro if the target machine has register windows.
+ This C expression returns the register number as seen by the
+ called function corresponding to the register number OUT as seen
+ by the calling function. Return OUT if register number OUT is not
+ an outbound register.
+
+`OUTGOING_REGNO (IN)'
+ Define this macro if the target machine has register windows.
+ This C expression returns the register number as seen by the
+ calling function corresponding to the register number IN as seen
+ by the called function. Return IN if register number IN is not an
+ inbound register.
+
+`LOCAL_REGNO (REGNO)'
+ Define this macro if the target machine has register windows.
+ This C expression returns true if the register is call-saved but
+ is in the register window. Unlike most call-saved registers, such
+ registers need not be explicitly restored on function exit or
+ during non-local gotos.
+
+
+\1f
+File: gccint.info, Node: Allocation Order, Next: Values in Registers, Prev: Register Basics, Up: Registers
+
+10.8.2 Order of Allocation of Registers
+---------------------------------------
+
+Registers are allocated in order.
+
+`REG_ALLOC_ORDER'
+ If defined, an initializer for a vector of integers, containing the
+ numbers of hard registers in the order in which GCC should prefer
+ to use them (from most preferred to least).
+
+ If this macro is not defined, registers are used lowest numbered
+ first (all else being equal).
-Trees
------
+ One use of this macro is on machines where the highest numbered
+ registers must always be saved and the save-multiple-registers
+ instruction supports only sequences of consecutive registers. On
+ such machines, define `REG_ALLOC_ORDER' to be an initializer that
+ lists the highest numbered allocable register first.
- This section is not here yet.
+`ORDER_REGS_FOR_LOCAL_ALLOC'
+ A C statement (sans semicolon) to choose the order in which to
+ allocate hard registers for pseudo-registers local to a basic
+ block.
+
+ Store the desired register order in the array `reg_alloc_order'.
+ Element 0 should be the register to allocate first; element 1, the
+ next register; and so on.
+
+ The macro body should not assume anything about the contents of
+ `reg_alloc_order' before execution of the macro.
+
+ On most machines, it is not necessary to define this macro.
\1f
-File: gccint.info, Node: Identifiers, Next: Containers, Prev: Macros and Functions, Up: Tree overview
+File: gccint.info, Node: Values in Registers, Next: Leaf Functions, Prev: Allocation Order, Up: Registers
+
+10.8.3 How Values Fit in Registers
+----------------------------------
+
+This section discusses the macros that describe which kinds of values
+(specifically, which machine modes) each register can hold, and how many
+consecutive registers are needed for a given mode.
+
+`HARD_REGNO_NREGS (REGNO, MODE)'
+ A C expression for the number of consecutive hard registers,
+ starting at register number REGNO, required to hold a value of mode
+ MODE.
+
+ On a machine where all registers are exactly one word, a suitable
+ definition of this macro is
+
+ #define HARD_REGNO_NREGS(REGNO, MODE) \
+ ((GET_MODE_SIZE (MODE) + UNITS_PER_WORD - 1) \
+ / UNITS_PER_WORD)
+
+`HARD_REGNO_MODE_OK (REGNO, MODE)'
+ A C expression that is nonzero if it is permissible to store a
+ value of mode MODE in hard register number REGNO (or in several
+ registers starting with that one). For a machine where all
+ registers are equivalent, a suitable definition is
+
+ #define HARD_REGNO_MODE_OK(REGNO, MODE) 1
+
+ You need not include code to check for the numbers of fixed
+ registers, because the allocation mechanism considers them to be
+ always occupied.
+
+ On some machines, double-precision values must be kept in even/odd
+ register pairs. You can implement that by defining this macro to
+ reject odd register numbers for such modes.
+
+ The minimum requirement for a mode to be OK in a register is that
+ the `movMODE' instruction pattern support moves between the
+ register and other hard register in the same class and that moving
+ a value into the register and back out not alter it.
+
+ Since the same instruction used to move `word_mode' will work for
+ all narrower integer modes, it is not necessary on any machine for
+ `HARD_REGNO_MODE_OK' to distinguish between these modes, provided
+ you define patterns `movhi', etc., to take advantage of this. This
+ is useful because of the interaction between `HARD_REGNO_MODE_OK'
+ and `MODES_TIEABLE_P'; it is very desirable for all integer modes
+ to be tieable.
+
+ Many machines have special registers for floating point arithmetic.
+ Often people assume that floating point machine modes are allowed
+ only in floating point registers. This is not true. Any
+ registers that can hold integers can safely _hold_ a floating
+ point machine mode, whether or not floating arithmetic can be done
+ on it in those registers. Integer move instructions can be used
+ to move the values.
+
+ On some machines, though, the converse is true: fixed-point machine
+ modes may not go in floating registers. This is true if the
+ floating registers normalize any value stored in them, because
+ storing a non-floating value there would garble it. In this case,
+ `HARD_REGNO_MODE_OK' should reject fixed-point machine modes in
+ floating registers. But if the floating registers do not
+ automatically normalize, if you can store any bit pattern in one
+ and retrieve it unchanged without a trap, then any machine mode
+ may go in a floating register, so you can define this macro to say
+ so.
+
+ The primary significance of special floating registers is rather
+ that they are the registers acceptable in floating point arithmetic
+ instructions. However, this is of no concern to
+ `HARD_REGNO_MODE_OK'. You handle it by writing the proper
+ constraints for those instructions.
+
+ On some machines, the floating registers are especially slow to
+ access, so that it is better to store a value in a stack frame
+ than in such a register if floating point arithmetic is not being
+ done. As long as the floating registers are not in class
+ `GENERAL_REGS', they will not be used unless some pattern's
+ constraint asks for one.
+
+`MODES_TIEABLE_P (MODE1, MODE2)'
+ A C expression that is nonzero if a value of mode MODE1 is
+ accessible in mode MODE2 without copying.
+
+ If `HARD_REGNO_MODE_OK (R, MODE1)' and `HARD_REGNO_MODE_OK (R,
+ MODE2)' are always the same for any R, then `MODES_TIEABLE_P
+ (MODE1, MODE2)' should be nonzero. If they differ for any R, you
+ should define this macro to return zero unless some other
+ mechanism ensures the accessibility of the value in a narrower
+ mode.
+
+ You should define this macro to return nonzero in as many cases as
+ possible since doing so will allow GCC to perform better register
+ allocation.
+
+`AVOID_CCMODE_COPIES'
+ Define this macro if the compiler should avoid copies to/from
+ `CCmode' registers. You should only define this macro if support
+ for copying to/from `CCmode' is incomplete.
+
+\1f
+File: gccint.info, Node: Leaf Functions, Next: Stack Registers, Prev: Values in Registers, Up: Registers
+
+10.8.4 Handling Leaf Functions
+------------------------------
-Identifiers
------------
+On some machines, a leaf function (i.e., one which makes no calls) can
+run more efficiently if it does not make its own register window.
+Often this means it is required to receive its arguments in the
+registers where they are passed by the caller, instead of the registers
+where they would normally arrive.
+
+ The special treatment for leaf functions generally applies only when
+other conditions are met; for example, often they may use only those
+registers for its own variables and temporaries. We use the term "leaf
+function" to mean a function that is suitable for this special
+handling, so that functions with no calls are not necessarily "leaf
+functions".
+
+ GCC assigns register numbers before it knows whether the function is
+suitable for leaf function treatment. So it needs to renumber the
+registers in order to output a leaf function. The following macros
+accomplish this.
+
+`LEAF_REGISTERS'
+ Name of a char vector, indexed by hard register number, which
+ contains 1 for a register that is allowable in a candidate for leaf
+ function treatment.
+
+ If leaf function treatment involves renumbering the registers,
+ then the registers marked here should be the ones before
+ renumbering--those that GCC would ordinarily allocate. The
+ registers which will actually be used in the assembler code, after
+ renumbering, should not be marked with 1 in this vector.
+
+ Define this macro only if the target machine offers a way to
+ optimize the treatment of leaf functions.
+
+`LEAF_REG_REMAP (REGNO)'
+ A C expression whose value is the register number to which REGNO
+ should be renumbered, when a function is treated as a leaf
+ function.
+
+ If REGNO is a register number which should not appear in a leaf
+ function before renumbering, then the expression should yield -1,
+ which will cause the compiler to abort.
+
+ Define this macro only if the target machine offers a way to
+ optimize the treatment of leaf functions, and registers need to be
+ renumbered to do this.
+
+ `TARGET_ASM_FUNCTION_PROLOGUE' and `TARGET_ASM_FUNCTION_EPILOGUE'
+must usually treat leaf functions specially. They can test the C
+variable `current_function_is_leaf' which is nonzero for leaf
+functions. `current_function_is_leaf' is set prior to local register
+allocation and is valid for the remaining compiler passes. They can
+also test the C variable `current_function_uses_only_leaf_regs' which
+is nonzero for leaf functions which only use leaf registers.
+`current_function_uses_only_leaf_regs' is valid after reload and is
+only useful if `LEAF_REGISTERS' is defined.
- An `IDENTIFIER_NODE' represents a slightly more general concept that
-the standard C or C++ concept of identifier. In particular, an
-`IDENTIFIER_NODE' may contain a `$', or other extraordinary characters.
+\1f
+File: gccint.info, Node: Stack Registers, Prev: Leaf Functions, Up: Registers
+
+10.8.5 Registers That Form a Stack
+----------------------------------
- There are never two distinct `IDENTIFIER_NODE's representing the
-same identifier. Therefore, you may use pointer equality to compare
-`IDENTIFIER_NODE's, rather than using a routine like `strcmp'.
+There are special features to handle computers where some of the
+"registers" form a stack, as in the 80387 coprocessor for the 80386.
+Stack registers are normally written by pushing onto the stack, and are
+numbered relative to the top of the stack.
- You can use the following macros to access identifiers:
-`IDENTIFIER_POINTER'
- The string represented by the identifier, represented as a
- `char*'. This string is always `NUL'-terminated, and contains no
- embedded `NUL' characters.
+ Currently, GCC can only handle one group of stack-like registers, and
+they must be consecutively numbered.
-`IDENTIFIER_LENGTH'
- The length of the string returned by `IDENTIFIER_POINTER', not
- including the trailing `NUL'. This value of `IDENTIFIER_LENGTH
- (x)' is always the same as `strlen (IDENTIFIER_POINTER (x))'.
+`STACK_REGS'
+ Define this if the machine has any stack-like registers.
-`IDENTIFIER_OPNAME_P'
- This predicate holds if the identifier represents the name of an
- overloaded operator. In this case, you should not depend on the
- contents of either the `IDENTIFIER_POINTER' or the
- `IDENTIFIER_LENGTH'.
+`FIRST_STACK_REG'
+ The number of the first stack-like register. This one is the top
+ of the stack.
-`IDENTIFIER_TYPENAME_P'
- This predicate holds if the identifier represents the name of a
- user-defined conversion operator. In this case, the `TREE_TYPE' of
- the `IDENTIFIER_NODE' holds the type to which the conversion
- operator converts.
+`LAST_STACK_REG'
+ The number of the last stack-like register. This one is the
+ bottom of the stack.
+\1f
+File: gccint.info, Node: Register Classes, Next: Stack and Calling, Prev: Registers, Up: Target Macros
+
+10.9 Register Classes
+=====================
+
+On many machines, the numbered registers are not all equivalent. For
+example, certain registers may not be allowed for indexed addressing;
+certain registers may not be allowed in some instructions. These
+machine restrictions are described to the compiler using "register
+classes".
+
+ You define a number of register classes, giving each one a name and
+saying which of the registers belong to it. Then you can specify
+register classes that are allowed as operands to particular instruction
+patterns.
+
+ In general, each register will belong to several classes. In fact,
+one class must be named `ALL_REGS' and contain all the registers.
+Another class must be named `NO_REGS' and contain no registers. Often
+the union of two classes will be another class; however, this is not
+required.
+
+ One of the classes must be named `GENERAL_REGS'. There is nothing
+terribly special about the name, but the operand constraint letters `r'
+and `g' specify this class. If `GENERAL_REGS' is the same as
+`ALL_REGS', just define it as a macro which expands to `ALL_REGS'.
+
+ Order the classes so that if class X is contained in class Y then X
+has a lower class number than Y.
+
+ The way classes other than `GENERAL_REGS' are specified in operand
+constraints is through machine-dependent operand constraint letters.
+You can define such letters to correspond to various classes, then use
+them in operand constraints.
+
+ You should define a class for the union of two classes whenever some
+instruction allows both classes. For example, if an instruction allows
+either a floating point (coprocessor) register or a general register
+for a certain operand, you should define a class `FLOAT_OR_GENERAL_REGS'
+which includes both of them. Otherwise you will get suboptimal code.
+
+ You must also specify certain redundant information about the
+register classes: for each class, which classes contain it and which
+ones are contained in it; for each pair of classes, the largest class
+contained in their union.
+
+ When a value occupying several consecutive registers is expected in a
+certain class, all the registers used must belong to that class.
+Therefore, register classes cannot be used to enforce a requirement for
+a register pair to start with an even-numbered register. The way to
+specify this requirement is with `HARD_REGNO_MODE_OK'.
+
+ Register classes used for input-operands of bitwise-and or shift
+instructions have a special requirement: each such class must have, for
+each fixed-point machine mode, a subclass whose registers can transfer
+that mode to or from memory. For example, on some machines, the
+operations for single-byte values (`QImode') are limited to certain
+registers. When this is so, each register class that is used in a
+bitwise-and or shift instruction must have a subclass consisting of
+registers from which single-byte values can be loaded or stored. This
+is so that `PREFERRED_RELOAD_CLASS' can always have a possible value to
+return.
+
+`enum reg_class'
+ An enumeral type that must be defined with all the register class
+ names as enumeral values. `NO_REGS' must be first. `ALL_REGS'
+ must be the last register class, followed by one more enumeral
+ value, `LIM_REG_CLASSES', which is not a register class but rather
+ tells how many classes there are.
+
+ Each register class has a number, which is the value of casting
+ the class name to type `int'. The number serves as an index in
+ many of the tables described below.
+
+`N_REG_CLASSES'
+ The number of distinct register classes, defined as follows:
+
+ #define N_REG_CLASSES (int) LIM_REG_CLASSES
+
+`REG_CLASS_NAMES'
+ An initializer containing the names of the register classes as C
+ string constants. These names are used in writing some of the
+ debugging dumps.
+
+`REG_CLASS_CONTENTS'
+ An initializer containing the contents of the register classes, as
+ integers which are bit masks. The Nth integer specifies the
+ contents of class N. The way the integer MASK is interpreted is
+ that register R is in the class if `MASK & (1 << R)' is 1.
+
+ When the machine has more than 32 registers, an integer does not
+ suffice. Then the integers are replaced by sub-initializers,
+ braced groupings containing several integers. Each
+ sub-initializer must be suitable as an initializer for the type
+ `HARD_REG_SET' which is defined in `hard-reg-set.h'. In this
+ situation, the first integer in each sub-initializer corresponds to
+ registers 0 through 31, the second integer to registers 32 through
+ 63, and so on.
+
+`REGNO_REG_CLASS (REGNO)'
+ A C expression whose value is a register class containing hard
+ register REGNO. In general there is more than one such class;
+ choose a class which is "minimal", meaning that no smaller class
+ also contains the register.
+
+`BASE_REG_CLASS'
+ A macro whose definition is the name of the class to which a valid
+ base register must belong. A base register is one used in an
+ address which is the register value plus a displacement.
+
+`MODE_BASE_REG_CLASS (MODE)'
+ This is a variation of the `BASE_REG_CLASS' macro which allows the
+ selection of a base register in a mode depenedent manner. If MODE
+ is VOIDmode then it should return the same value as
+ `BASE_REG_CLASS'.
+
+`INDEX_REG_CLASS'
+ A macro whose definition is the name of the class to which a valid
+ index register must belong. An index register is one used in an
+ address where its value is either multiplied by a scale factor or
+ added to another register (as well as added to a displacement).
+
+`REG_CLASS_FROM_LETTER (CHAR)'
+ A C expression which defines the machine-dependent operand
+ constraint letters for register classes. If CHAR is such a
+ letter, the value should be the register class corresponding to
+ it. Otherwise, the value should be `NO_REGS'. The register
+ letter `r', corresponding to class `GENERAL_REGS', will not be
+ passed to this macro; you do not need to handle it.
+
+`REGNO_OK_FOR_BASE_P (NUM)'
+ A C expression which is nonzero if register number NUM is suitable
+ for use as a base register in operand addresses. It may be either
+ a suitable hard register or a pseudo register that has been
+ allocated such a hard register.
+
+`REGNO_MODE_OK_FOR_BASE_P (NUM, MODE)'
+ A C expression that is just like `REGNO_OK_FOR_BASE_P', except that
+ that expression may examine the mode of the memory reference in
+ MODE. You should define this macro if the mode of the memory
+ reference affects whether a register may be used as a base
+ register. If you define this macro, the compiler will use it
+ instead of `REGNO_OK_FOR_BASE_P'.
+
+`REGNO_OK_FOR_INDEX_P (NUM)'
+ A C expression which is nonzero if register number NUM is suitable
+ for use as an index register in operand addresses. It may be
+ either a suitable hard register or a pseudo register that has been
+ allocated such a hard register.
+
+ The difference between an index register and a base register is
+ that the index register may be scaled. If an address involves the
+ sum of two registers, neither one of them scaled, then either one
+ may be labeled the "base" and the other the "index"; but whichever
+ labeling is used must fit the machine's constraints of which
+ registers may serve in each capacity. The compiler will try both
+ labelings, looking for one that is valid, and will reload one or
+ both registers only if neither labeling works.
+
+`PREFERRED_RELOAD_CLASS (X, CLASS)'
+ A C expression that places additional restrictions on the register
+ class to use when it is necessary to copy value X into a register
+ in class CLASS. The value is a register class; perhaps CLASS, or
+ perhaps another, smaller class. On many machines, the following
+ definition is safe:
+
+ #define PREFERRED_RELOAD_CLASS(X,CLASS) CLASS
+
+ Sometimes returning a more restrictive class makes better code.
+ For example, on the 68000, when X is an integer constant that is
+ in range for a `moveq' instruction, the value of this macro is
+ always `DATA_REGS' as long as CLASS includes the data registers.
+ Requiring a data register guarantees that a `moveq' will be used.
+
+ If X is a `const_double', by returning `NO_REGS' you can force X
+ into a memory constant. This is useful on certain machines where
+ immediate floating values cannot be loaded into certain kinds of
+ registers.
+
+`PREFERRED_OUTPUT_RELOAD_CLASS (X, CLASS)'
+ Like `PREFERRED_RELOAD_CLASS', but for output reloads instead of
+ input reloads. If you don't define this macro, the default is to
+ use CLASS, unchanged.
+
+`LIMIT_RELOAD_CLASS (MODE, CLASS)'
+ A C expression that places additional restrictions on the register
+ class to use when it is necessary to be able to hold a value of
+ mode MODE in a reload register for which class CLASS would
+ ordinarily be used.
+
+ Unlike `PREFERRED_RELOAD_CLASS', this macro should be used when
+ there are certain modes that simply can't go in certain reload
+ classes.
+
+ The value is a register class; perhaps CLASS, or perhaps another,
+ smaller class.
+
+ Don't define this macro unless the target machine has limitations
+ which require the macro to do something nontrivial.
+
+`SECONDARY_RELOAD_CLASS (CLASS, MODE, X)'
+`SECONDARY_INPUT_RELOAD_CLASS (CLASS, MODE, X)'
+`SECONDARY_OUTPUT_RELOAD_CLASS (CLASS, MODE, X)'
+ Many machines have some registers that cannot be copied directly
+ to or from memory or even from other types of registers. An
+ example is the `MQ' register, which on most machines, can only be
+ copied to or from general registers, but not memory. Some
+ machines allow copying all registers to and from memory, but
+ require a scratch register for stores to some memory locations
+ (e.g., those with symbolic address on the RT, and those with
+ certain symbolic address on the Sparc when compiling PIC). In
+ some cases, both an intermediate and a scratch register are
+ required.
+
+ You should define these macros to indicate to the reload phase
+ that it may need to allocate at least one register for a reload in
+ addition to the register to contain the data. Specifically, if
+ copying X to a register CLASS in MODE requires an intermediate
+ register, you should define `SECONDARY_INPUT_RELOAD_CLASS' to
+ return the largest register class all of whose registers can be
+ used as intermediate registers or scratch registers.
+
+ If copying a register CLASS in MODE to X requires an intermediate
+ or scratch register, `SECONDARY_OUTPUT_RELOAD_CLASS' should be
+ defined to return the largest register class required. If the
+ requirements for input and output reloads are the same, the macro
+ `SECONDARY_RELOAD_CLASS' should be used instead of defining both
+ macros identically.
+
+ The values returned by these macros are often `GENERAL_REGS'.
+ Return `NO_REGS' if no spare register is needed; i.e., if X can be
+ directly copied to or from a register of CLASS in MODE without
+ requiring a scratch register. Do not define this macro if it
+ would always return `NO_REGS'.
+
+ If a scratch register is required (either with or without an
+ intermediate register), you should define patterns for
+ `reload_inM' or `reload_outM', as required (*note Standard
+ Names::. These patterns, which will normally be implemented with
+ a `define_expand', should be similar to the `movM' patterns,
+ except that operand 2 is the scratch register.
+
+ Define constraints for the reload register and scratch register
+ that contain a single register class. If the original reload
+ register (whose class is CLASS) can meet the constraint given in
+ the pattern, the value returned by these macros is used for the
+ class of the scratch register. Otherwise, two additional reload
+ registers are required. Their classes are obtained from the
+ constraints in the insn pattern.
+
+ X might be a pseudo-register or a `subreg' of a pseudo-register,
+ which could either be in a hard register or in memory. Use
+ `true_regnum' to find out; it will return -1 if the pseudo is in
+ memory and the hard register number if it is in a register.
+
+ These macros should not be used in the case where a particular
+ class of registers can only be copied to memory and not to another
+ class of registers. In that case, secondary reload registers are
+ not needed and would not be helpful. Instead, a stack location
+ must be used to perform the copy and the `movM' pattern should use
+ memory as an intermediate storage. This case often occurs between
+ floating-point and general registers.
+
+`SECONDARY_MEMORY_NEEDED (CLASS1, CLASS2, M)'
+ Certain machines have the property that some registers cannot be
+ copied to some other registers without using memory. Define this
+ macro on those machines to be a C expression that is nonzero if
+ objects of mode M in registers of CLASS1 can only be copied to
+ registers of class CLASS2 by storing a register of CLASS1 into
+ memory and loading that memory location into a register of CLASS2.
+
+ Do not define this macro if its value would always be zero.
+
+`SECONDARY_MEMORY_NEEDED_RTX (MODE)'
+ Normally when `SECONDARY_MEMORY_NEEDED' is defined, the compiler
+ allocates a stack slot for a memory location needed for register
+ copies. If this macro is defined, the compiler instead uses the
+ memory location defined by this macro.
+
+ Do not define this macro if you do not define
+ `SECONDARY_MEMORY_NEEDED'.
+
+`SECONDARY_MEMORY_NEEDED_MODE (MODE)'
+ When the compiler needs a secondary memory location to copy
+ between two registers of mode MODE, it normally allocates
+ sufficient memory to hold a quantity of `BITS_PER_WORD' bits and
+ performs the store and load operations in a mode that many bits
+ wide and whose class is the same as that of MODE.
+
+ This is right thing to do on most machines because it ensures that
+ all bits of the register are copied and prevents accesses to the
+ registers in a narrower mode, which some machines prohibit for
+ floating-point registers.
+
+ However, this default behavior is not correct on some machines,
+ such as the DEC Alpha, that store short integers in floating-point
+ registers differently than in integer registers. On those
+ machines, the default widening will not work correctly and you
+ must define this macro to suppress that widening in some cases.
+ See the file `alpha.h' for details.
+
+ Do not define this macro if you do not define
+ `SECONDARY_MEMORY_NEEDED' or if widening MODE to a mode that is
+ `BITS_PER_WORD' bits wide is correct for your machine.
+
+`SMALL_REGISTER_CLASSES'
+ On some machines, it is risky to let hard registers live across
+ arbitrary insns. Typically, these machines have instructions that
+ require values to be in specific registers (like an accumulator),
+ and reload will fail if the required hard register is used for
+ another purpose across such an insn.
+
+ Define `SMALL_REGISTER_CLASSES' to be an expression with a nonzero
+ value on these machines. When this macro has a nonzero value, the
+ compiler will try to minimize the lifetime of hard registers.
+
+ It is always safe to define this macro with a nonzero value, but
+ if you unnecessarily define it, you will reduce the amount of
+ optimizations that can be performed in some cases. If you do not
+ define this macro with a nonzero value when it is required, the
+ compiler will run out of spill registers and print a fatal error
+ message. For most machines, you should not define this macro at
+ all.
+
+`CLASS_LIKELY_SPILLED_P (CLASS)'
+ A C expression whose value is nonzero if pseudos that have been
+ assigned to registers of class CLASS would likely be spilled
+ because registers of CLASS are needed for spill registers.
+
+ The default value of this macro returns 1 if CLASS has exactly one
+ register and zero otherwise. On most machines, this default
+ should be used. Only define this macro to some other expression
+ if pseudos allocated by `local-alloc.c' end up in memory because
+ their hard registers were needed for spill registers. If this
+ macro returns nonzero for those classes, those pseudos will only
+ be allocated by `global.c', which knows how to reallocate the
+ pseudo to another register. If there would not be another
+ register available for reallocation, you should not change the
+ definition of this macro since the only effect of such a
+ definition would be to slow down register allocation.
+
+`CLASS_MAX_NREGS (CLASS, MODE)'
+ A C expression for the maximum number of consecutive registers of
+ class CLASS needed to hold a value of mode MODE.
+
+ This is closely related to the macro `HARD_REGNO_NREGS'. In fact,
+ the value of the macro `CLASS_MAX_NREGS (CLASS, MODE)' should be
+ the maximum value of `HARD_REGNO_NREGS (REGNO, MODE)' for all
+ REGNO values in the class CLASS.
+
+ This macro helps control the handling of multiple-word values in
+ the reload pass.
+
+`CLASS_CANNOT_CHANGE_MODE'
+ If defined, a C expression for a class that contains registers for
+ which the compiler may not change modes arbitrarily.
+
+`CLASS_CANNOT_CHANGE_MODE_P(FROM, TO)'
+ A C expression that is true if, for a register in
+ `CLASS_CANNOT_CHANGE_MODE', the requested mode punning is invalid.
+
+ For the example, loading 32-bit integer or floating-point objects
+ into floating-point registers on the Alpha extends them to 64 bits.
+ Therefore loading a 64-bit object and then storing it as a 32-bit
+ object does not store the low-order 32 bits, as would be the case
+ for a normal register. Therefore, `alpha.h' defines
+ `CLASS_CANNOT_CHANGE_MODE' as `FLOAT_REGS' and
+ `CLASS_CANNOT_CHANGE_MODE_P' restricts mode changes to same-size
+ modes.
+
+ Compare this to IA-64, which extends floating-point values to 82
+ bits, and stores 64-bit integers in a different format than 64-bit
+ doubles. Therefore `CLASS_CANNOT_CHANGE_MODE_P' is always true.
+
+ Three other special macros describe which operands fit which
+constraint letters.
+
+`CONST_OK_FOR_LETTER_P (VALUE, C)'
+ A C expression that defines the machine-dependent operand
+ constraint letters (`I', `J', `K', ... `P') that specify
+ particular ranges of integer values. If C is one of those
+ letters, the expression should check that VALUE, an integer, is in
+ the appropriate range and return 1 if so, 0 otherwise. If C is
+ not one of those letters, the value should be 0 regardless of
+ VALUE.
+
+`CONST_DOUBLE_OK_FOR_LETTER_P (VALUE, C)'
+ A C expression that defines the machine-dependent operand
+ constraint letters that specify particular ranges of
+ `const_double' values (`G' or `H').
+
+ If C is one of those letters, the expression should check that
+ VALUE, an RTX of code `const_double', is in the appropriate range
+ and return 1 if so, 0 otherwise. If C is not one of those
+ letters, the value should be 0 regardless of VALUE.
+
+ `const_double' is used for all floating-point constants and for
+ `DImode' fixed-point constants. A given letter can accept either
+ or both kinds of values. It can use `GET_MODE' to distinguish
+ between these kinds.
+
+`EXTRA_CONSTRAINT (VALUE, C)'
+ A C expression that defines the optional machine-dependent
+ constraint letters that can be used to segregate specific types of
+ operands, usually memory references, for the target machine. Any
+ letter that is not elsewhere defined and not matched by
+ `REG_CLASS_FROM_LETTER' may be used. Normally this macro will not
+ be defined.
+
+ If it is required for a particular target machine, it should
+ return 1 if VALUE corresponds to the operand type represented by
+ the constraint letter C. If C is not defined as an extra
+ constraint, the value returned should be 0 regardless of VALUE.
+
+ For example, on the ROMP, load instructions cannot have their
+ output in r0 if the memory reference contains a symbolic address.
+ Constraint letter `Q' is defined as representing a memory address
+ that does _not_ contain a symbolic address. An alternative is
+ specified with a `Q' constraint on the input and `r' on the
+ output. The next alternative specifies `m' on the input and a
+ register class that does not include r0 on the output.
\1f
-File: gccint.info, Node: Containers, Prev: Identifiers, Up: Tree overview
+File: gccint.info, Node: Stack and Calling, Next: Varargs, Prev: Register Classes, Up: Target Macros
-Containers
-----------
+10.10 Stack Layout and Calling Conventions
+==========================================
- Two common container data structures can be represented directly with
-tree nodes. A `TREE_LIST' is a singly linked list containing two trees
-per node. These are the `TREE_PURPOSE' and `TREE_VALUE' of each node.
-(Often, the `TREE_PURPOSE' contains some kind of tag, or additional
-information, while the `TREE_VALUE' contains the majority of the
-payload. In other cases, the `TREE_PURPOSE' is simply `NULL_TREE',
-while in still others both the `TREE_PURPOSE' and `TREE_VALUE' are of
-equal stature.) Given one `TREE_LIST' node, the next node is found by
-following the `TREE_CHAIN'. If the `TREE_CHAIN' is `NULL_TREE', then
-you have reached the end of the list.
+This describes the stack layout and calling conventions.
- A `TREE_VEC' is a simple vector. The `TREE_VEC_LENGTH' is an
-integer (not a tree) giving the number of nodes in the vector. The
-nodes themselves are accessed using the `TREE_VEC_ELT' macro, which
-takes two arguments. The first is the `TREE_VEC' in question; the
-second is an integer indicating which element in the vector is desired.
-The elements are indexed from zero.
+* Menu:
+
+* Frame Layout::
+* Exception Handling::
+* Stack Checking::
+* Frame Registers::
+* Elimination::
+* Stack Arguments::
+* Register Arguments::
+* Scalar Return::
+* Aggregate Return::
+* Caller Saves::
+* Function Entry::
+* Profiling::
+* Tail Calls::
+
+\1f
+File: gccint.info, Node: Frame Layout, Next: Exception Handling, Up: Stack and Calling
+
+10.10.1 Basic Stack Layout
+--------------------------
+
+Here is the basic stack layout.
+
+`STACK_GROWS_DOWNWARD'
+ Define this macro if pushing a word onto the stack moves the stack
+ pointer to a smaller address.
+
+ When we say, "define this macro if ...," it means that the
+ compiler checks this macro only with `#ifdef' so the precise
+ definition used does not matter.
+
+`STACK_PUSH_CODE'
+ This macro defines the operation used when something is pushed on
+ the stack. In RTL, a push operation will be `(set (mem
+ (STACK_PUSH_CODE (reg sp))) ...)'
+
+ The choices are `PRE_DEC', `POST_DEC', `PRE_INC', and `POST_INC'.
+ Which of these is correct depends on the stack direction and on
+ whether the stack pointer points to the last item on the stack or
+ whether it points to the space for the next item on the stack.
+
+ The default is `PRE_DEC' when `STACK_GROWS_DOWNWARD' is defined,
+ which is almost always right, and `PRE_INC' otherwise, which is
+ often wrong.
+
+`FRAME_GROWS_DOWNWARD'
+ Define this macro if the addresses of local variable slots are at
+ negative offsets from the frame pointer.
+
+`ARGS_GROW_DOWNWARD'
+ Define this macro if successive arguments to a function occupy
+ decreasing addresses on the stack.
+
+`STARTING_FRAME_OFFSET'
+ Offset from the frame pointer to the first local variable slot to
+ be allocated.
+
+ If `FRAME_GROWS_DOWNWARD', find the next slot's offset by
+ subtracting the first slot's length from `STARTING_FRAME_OFFSET'.
+ Otherwise, it is found by adding the length of the first slot to
+ the value `STARTING_FRAME_OFFSET'.
+
+`STACK_POINTER_OFFSET'
+ Offset from the stack pointer register to the first location at
+ which outgoing arguments are placed. If not specified, the
+ default value of zero is used. This is the proper value for most
+ machines.
+
+ If `ARGS_GROW_DOWNWARD', this is the offset to the location above
+ the first location at which outgoing arguments are placed.
+
+`FIRST_PARM_OFFSET (FUNDECL)'
+ Offset from the argument pointer register to the first argument's
+ address. On some machines it may depend on the data type of the
+ function.
+
+ If `ARGS_GROW_DOWNWARD', this is the offset to the location above
+ the first argument's address.
+
+`STACK_DYNAMIC_OFFSET (FUNDECL)'
+ Offset from the stack pointer register to an item dynamically
+ allocated on the stack, e.g., by `alloca'.
+
+ The default value for this macro is `STACK_POINTER_OFFSET' plus the
+ length of the outgoing arguments. The default is correct for most
+ machines. See `function.c' for details.
+
+`DYNAMIC_CHAIN_ADDRESS (FRAMEADDR)'
+ A C expression whose value is RTL representing the address in a
+ stack frame where the pointer to the caller's frame is stored.
+ Assume that FRAMEADDR is an RTL expression for the address of the
+ stack frame itself.
+
+ If you don't define this macro, the default is to return the value
+ of FRAMEADDR--that is, the stack frame address is also the address
+ of the stack word that points to the previous frame.
+
+`SETUP_FRAME_ADDRESSES'
+ If defined, a C expression that produces the machine-specific code
+ to setup the stack so that arbitrary frames can be accessed. For
+ example, on the Sparc, we must flush all of the register windows
+ to the stack before we can access arbitrary stack frames. You
+ will seldom need to define this macro.
+
+`BUILTIN_SETJMP_FRAME_VALUE'
+ If defined, a C expression that contains an rtx that is used to
+ store the address of the current frame into the built in `setjmp'
+ buffer. The default value, `virtual_stack_vars_rtx', is correct
+ for most machines. One reason you may need to define this macro
+ is if `hard_frame_pointer_rtx' is the appropriate value on your
+ machine.
+
+`RETURN_ADDR_RTX (COUNT, FRAMEADDR)'
+ A C expression whose value is RTL representing the value of the
+ return address for the frame COUNT steps up from the current
+ frame, after the prologue. FRAMEADDR is the frame pointer of the
+ COUNT frame, or the frame pointer of the COUNT - 1 frame if
+ `RETURN_ADDR_IN_PREVIOUS_FRAME' is defined.
+
+ The value of the expression must always be the correct address when
+ COUNT is zero, but may be `NULL_RTX' if there is not way to
+ determine the return address of other frames.
+
+`RETURN_ADDR_IN_PREVIOUS_FRAME'
+ Define this if the return address of a particular stack frame is
+ accessed from the frame pointer of the previous stack frame.
+
+`INCOMING_RETURN_ADDR_RTX'
+ A C expression whose value is RTL representing the location of the
+ incoming return address at the beginning of any function, before
+ the prologue. This RTL is either a `REG', indicating that the
+ return value is saved in `REG', or a `MEM' representing a location
+ in the stack.
+
+ You only need to define this macro if you want to support call
+ frame debugging information like that provided by DWARF 2.
+
+ If this RTL is a `REG', you should also define
+ `DWARF_FRAME_RETURN_COLUMN' to `DWARF_FRAME_REGNUM (REGNO)'.
+
+`INCOMING_FRAME_SP_OFFSET'
+ A C expression whose value is an integer giving the offset, in
+ bytes, from the value of the stack pointer register to the top of
+ the stack frame at the beginning of any function, before the
+ prologue. The top of the frame is defined to be the value of the
+ stack pointer in the previous frame, just before the call
+ instruction.
+
+ You only need to define this macro if you want to support call
+ frame debugging information like that provided by DWARF 2.
+
+`ARG_POINTER_CFA_OFFSET (FUNDECL)'
+ A C expression whose value is an integer giving the offset, in
+ bytes, from the argument pointer to the canonical frame address
+ (cfa). The final value should coincide with that calculated by
+ `INCOMING_FRAME_SP_OFFSET'. Which is unfortunately not usable
+ during virtual register instantiation.
+
+ The default value for this macro is `FIRST_PARM_OFFSET (fundecl)',
+ which is correct for most machines; in general, the arguments are
+ found immediately before the stack frame. Note that this is not
+ the case on some targets that save registers into the caller's
+ frame, such as SPARC and rs6000, and so such targets need to
+ define this macro.
+
+ You only need to define this macro if the default is incorrect,
+ and you want to support call frame debugging information like that
+ provided by DWARF 2.
+
+`SMALL_STACK'
+ Define this macro if the stack size for the target is very small.
+ This has the effect of disabling gcc's built-in `alloca', though
+ `__builtin_alloca' is not affected.
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Target Attributes, Next: Misc, Prev: Mode Switching, Up: Target Macros
-
-Defining target-specific uses of `__attribute__'
-================================================
-
- Target-specific attributes may be defined for functions, data and
-types. These are described using the following target hooks; they also
-need to be documented in `extend.texi'.
-
- - Target Hook: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
- If defined, this target hook points to an array of `struct
- attribute_spec' (defined in `tree.h') specifying the machine
- specific attributes for this target and some of the restrictions
- on the entities to which these attributes are applied and the
- arguments they take.
-
- - Target Hook: int TARGET_COMP_TYPE_ATTRIBUTES (tree TYPE1, tree TYPE2)
- If defined, this target hook is a function which returns zero if
- the attributes on TYPE1 and TYPE2 are incompatible, one if they
- are compatible, and two if they are nearly compatible (which
- causes a warning to be generated). If this is not defined,
- machine-specific attributes are supposed always to be compatible.
-
- - Target Hook: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree TYPE)
- If defined, this target hook is a function which assigns default
- attributes to newly defined TYPE.
-
- - Target Hook: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree TYPE1, tree
- TYPE2)
- Define this target hook if the merging of type attributes needs
- special handling. If defined, the result is a list of the combined
- `TYPE_ATTRIBUTES' of TYPE1 and TYPE2. It is assumed that
- `comptypes' has already been called and returned 1. This function
- may call `merge_attributes' to handle machine-independent merging.
-
- - Target Hook: tree TARGET_MERGE_DECL_ATTRIBUTES (tree OLDDECL, tree
- NEWDECL)
- Define this target hook if the merging of decl attributes needs
- special handling. If defined, the result is a list of the combined
- `DECL_ATTRIBUTES' of OLDDECL and NEWDECL. NEWDECL is a duplicate
- declaration of OLDDECL. Examples of when this is needed are when
- one attribute overrides another, or when an attribute is nullified
- by a subsequent definition. This function may call
- `merge_attributes' to handle machine-independent merging.
-
- If the only target-specific handling you require is `dllimport' for
- Windows targets, you should define the macro
- `TARGET_DLLIMPORT_DECL_ATTRIBUTES'. This links in a function
- called `merge_dllimport_decl_attributes' which can then be defined
- as the expansion of `TARGET_MERGE_DECL_ATTRIBUTES'. This is done
- in `i386/cygwin.h' and `i386/i386.c', for example.
-
- - Target Hook: void TARGET_INSERT_ATTRIBUTES (tree NODE, tree
- *ATTR_PTR)
- Define this target hook if you want to be able to add attributes
- to a decl when it is being created. This is normally useful for
- back ends which wish to implement a pragma by using the attributes
- which correspond to the pragma's effect. The NODE argument is the
- decl which is being created. The ATTR_PTR argument is a pointer
- to the attribute list for this decl. The list itself should not
- be modified, since it may be shared with other decls, but
- attributes may be chained on the head of the list and `*ATTR_PTR'
- modified to point to the new attributes, or a copy of the list may
- be made if further changes are needed.
-
- - Target Hook: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (tree FNDECL)
- This target hook returns `true' if it is ok to inline FNDECL into
- the current function, despite its having target-specific
- attributes, `false' otherwise. By default, if a function has a
- target specific attribute attached to it, it will not be inlined.
-
-\1f
-File: gccint.info, Node: Misc, Prev: Target Attributes, Up: Target Macros
-
-Miscellaneous Parameters
-========================
-
- Here are several miscellaneous parameters.
-
-`PREDICATE_CODES'
- Define this if you have defined special-purpose predicates in the
- file `MACHINE.c'. This macro is called within an initializer of an
- array of structures. The first field in the structure is the name
- of a predicate and the second field is an array of rtl codes. For
- each predicate, list all rtl codes that can be in expressions
- matched by the predicate. The list should have a trailing comma.
- Here is an example of two entries in the list for a typical RISC
- machine:
-
- #define PREDICATE_CODES \
- {"gen_reg_rtx_operand", {SUBREG, REG}}, \
- {"reg_or_short_cint_operand", {SUBREG, REG, CONST_INT}},
-
- Defining this macro does not affect the generated code (however,
- incorrect definitions that omit an rtl code that may be matched by
- the predicate can cause the compiler to malfunction). Instead, it
- allows the table built by `genrecog' to be more compact and
- efficient, thus speeding up the compiler. The most important
- predicates to include in the list specified by this macro are
- those used in the most insn patterns.
-
- For each predicate function named in `PREDICATE_CODES', a
- declaration will be generated in `insn-codes.h'.
-
-`SPECIAL_MODE_PREDICATES'
- Define this if you have special predicates that know special things
- about modes. Genrecog will warn about certain forms of
- `match_operand' without a mode; if the operand predicate is listed
- in `SPECIAL_MODE_PREDICATES', the warning will be suppressed.
-
- Here is an example from the IA-32 port (`ext_register_operand'
- specially checks for `HImode' or `SImode' in preparation for a
- byte extraction from `%ah' etc.).
-
- #define SPECIAL_MODE_PREDICATES \
- "ext_register_operand",
-
-`CASE_VECTOR_MODE'
- An alias for a machine mode name. This is the machine mode that
- elements of a jump-table should have.
-
-`CASE_VECTOR_SHORTEN_MODE (MIN_OFFSET, MAX_OFFSET, BODY)'
- Optional: return the preferred mode for an `addr_diff_vec' when
- the minimum and maximum offset are known. If you define this, it
- enables extra code in branch shortening to deal with
- `addr_diff_vec'. To make this work, you also have to define
- INSN_ALIGN and make the alignment for `addr_diff_vec' explicit.
- The BODY argument is provided so that the offset_unsigned and scale
- flags can be updated.
-
-`CASE_VECTOR_PC_RELATIVE'
- Define this macro to be a C expression to indicate when jump-tables
- should contain relative addresses. If jump-tables never contain
- relative addresses, then you need not define this macro.
-
-`CASE_DROPS_THROUGH'
- Define this if control falls through a `case' insn when the index
- value is out of range. This means the specified default-label is
- actually ignored by the `case' insn proper.
-
-`CASE_VALUES_THRESHOLD'
- Define this to be the smallest number of different values for
- which it is best to use a jump-table instead of a tree of
- conditional branches. The default is four for machines with a
- `casesi' instruction and five otherwise. This is best for most
- machines.
-
-`WORD_REGISTER_OPERATIONS'
- Define this macro if operations between registers with integral
- mode smaller than a word are always performed on the entire
- register. Most RISC machines have this property and most CISC
- machines do not.
-
-`LOAD_EXTEND_OP (MODE)'
- Define this macro to be a C expression indicating when insns that
- read memory in MODE, an integral mode narrower than a word, set the
- bits outside of MODE to be either the sign-extension or the
- zero-extension of the data read. Return `SIGN_EXTEND' for values
- of MODE for which the insn sign-extends, `ZERO_EXTEND' for which
- it zero-extends, and `NIL' for other modes.
-
- This macro is not called with MODE non-integral or with a width
- greater than or equal to `BITS_PER_WORD', so you may return any
- value in this case. Do not define this macro if it would always
- return `NIL'. On machines where this macro is defined, you will
- normally define it as the constant `SIGN_EXTEND' or `ZERO_EXTEND'.
-
-`SHORT_IMMEDIATES_SIGN_EXTEND'
- Define this macro if loading short immediate values into registers
- sign extends.
-
-`FIXUNS_TRUNC_LIKE_FIX_TRUNC'
- Define this macro if the same instructions that convert a floating
- point number to a signed fixed point number also convert validly
- to an unsigned one.
-
-`MOVE_MAX'
- The maximum number of bytes that a single instruction can move
- quickly between memory and registers or between two memory
- locations.
-
-`MAX_MOVE_MAX'
- The maximum number of bytes that a single instruction can move
- quickly between memory and registers or between two memory
- locations. If this is undefined, the default is `MOVE_MAX'.
- Otherwise, it is the constant value that is the largest value that
- `MOVE_MAX' can have at run-time.
-
-`SHIFT_COUNT_TRUNCATED'
- A C expression that is nonzero if on this machine the number of
- bits actually used for the count of a shift operation is equal to
- the number of bits needed to represent the size of the object
- being shifted. When this macro is nonzero, the compiler will
- assume that it is safe to omit a sign-extend, zero-extend, and
- certain bitwise `and' instructions that truncates the count of a
- shift operation. On machines that have instructions that act on
- bit-fields at variable positions, which may include `bit test'
- instructions, a nonzero `SHIFT_COUNT_TRUNCATED' also enables
- deletion of truncations of the values that serve as arguments to
- bit-field instructions.
-
- If both types of instructions truncate the count (for shifts) and
- position (for bit-field operations), or if no variable-position
- bit-field instructions exist, you should define this macro.
-
- However, on some machines, such as the 80386 and the 680x0,
- truncation only applies to shift operations and not the (real or
- pretended) bit-field operations. Define `SHIFT_COUNT_TRUNCATED'
- to be zero on such machines. Instead, add patterns to the `md'
- file that include the implied truncation of the shift instructions.
-
- You need not define this macro if it would always have the value
- of zero.
-
-`TRULY_NOOP_TRUNCATION (OUTPREC, INPREC)'
- A C expression which is nonzero if on this machine it is safe to
- "convert" an integer of INPREC bits to one of OUTPREC bits (where
- OUTPREC is smaller than INPREC) by merely operating on it as if it
- had only OUTPREC bits.
-
- On many machines, this expression can be 1.
-
- When `TRULY_NOOP_TRUNCATION' returns 1 for a pair of sizes for
- modes for which `MODES_TIEABLE_P' is 0, suboptimal code can result.
- If this is the case, making `TRULY_NOOP_TRUNCATION' return 0 in
- such cases may improve things.
-
-`STORE_FLAG_VALUE'
- A C expression describing the value returned by a comparison
- operator with an integral mode and stored by a store-flag
- instruction (`sCOND') when the condition is true. This
- description must apply to _all_ the `sCOND' patterns and all the
- comparison operators whose results have a `MODE_INT' mode.
-
- A value of 1 or -1 means that the instruction implementing the
- comparison operator returns exactly 1 or -1 when the comparison is
- true and 0 when the comparison is false. Otherwise, the value
- indicates which bits of the result are guaranteed to be 1 when the
- comparison is true. This value is interpreted in the mode of the
- comparison operation, which is given by the mode of the first
- operand in the `sCOND' pattern. Either the low bit or the sign
- bit of `STORE_FLAG_VALUE' be on. Presently, only those bits are
- used by the compiler.
-
- If `STORE_FLAG_VALUE' is neither 1 or -1, the compiler will
- generate code that depends only on the specified bits. It can also
- replace comparison operators with equivalent operations if they
- cause the required bits to be set, even if the remaining bits are
- undefined. For example, on a machine whose comparison operators
- return an `SImode' value and where `STORE_FLAG_VALUE' is defined as
- `0x80000000', saying that just the sign bit is relevant, the
- expression
-
- (ne:SI (and:SI X (const_int POWER-OF-2)) (const_int 0))
-
- can be converted to
-
- (ashift:SI X (const_int N))
-
- where N is the appropriate shift count to move the bit being
- tested into the sign bit.
-
- There is no way to describe a machine that always sets the
- low-order bit for a true value, but does not guarantee the value
- of any other bits, but we do not know of any machine that has such
- an instruction. If you are trying to port GCC to such a machine,
- include an instruction to perform a logical-and of the result with
- 1 in the pattern for the comparison operators and let us know at
- <gcc@gcc.gnu.org>.
-
- Often, a machine will have multiple instructions that obtain a
- value from a comparison (or the condition codes). Here are rules
- to guide the choice of value for `STORE_FLAG_VALUE', and hence the
- instructions to be used:
-
- * Use the shortest sequence that yields a valid definition for
- `STORE_FLAG_VALUE'. It is more efficient for the compiler to
- "normalize" the value (convert it to, e.g., 1 or 0) than for
- the comparison operators to do so because there may be
- opportunities to combine the normalization with other
- operations.
-
- * For equal-length sequences, use a value of 1 or -1, with -1
- being slightly preferred on machines with expensive jumps and
- 1 preferred on other machines.
-
- * As a second choice, choose a value of `0x80000001' if
- instructions exist that set both the sign and low-order bits
- but do not define the others.
-
- * Otherwise, use a value of `0x80000000'.
-
- Many machines can produce both the value chosen for
- `STORE_FLAG_VALUE' and its negation in the same number of
- instructions. On those machines, you should also define a pattern
- for those cases, e.g., one matching
-
- (set A (neg:M (ne:M B C)))
-
- Some machines can also perform `and' or `plus' operations on
- condition code values with less instructions than the corresponding
- `sCOND' insn followed by `and' or `plus'. On those machines,
- define the appropriate patterns. Use the names `incscc' and
- `decscc', respectively, for the patterns which perform `plus' or
- `minus' operations on condition code values. See `rs6000.md' for
- some examples. The GNU Superoptizer can be used to find such
- instruction sequences on other machines.
-
- You need not define `STORE_FLAG_VALUE' if the machine has no
- store-flag instructions.
-
-`FLOAT_STORE_FLAG_VALUE (MODE)'
- A C expression that gives a nonzero `REAL_VALUE_TYPE' value that is
- returned when comparison operators with floating-point results are
- true. Define this macro on machine that have comparison
- operations that return floating-point values. If there are no
- such operations, do not define this macro.
-
-`Pmode'
- An alias for the machine mode for pointers. On most machines,
- define this to be the integer mode corresponding to the width of a
- hardware pointer; `SImode' on 32-bit machine or `DImode' on 64-bit
- machines. On some machines you must define this to be one of the
- partial integer modes, such as `PSImode'.
-
- The width of `Pmode' must be at least as large as the value of
- `POINTER_SIZE'. If it is not equal, you must define the macro
- `POINTERS_EXTEND_UNSIGNED' to specify how pointers are extended to
- `Pmode'.
-
-`FUNCTION_MODE'
- An alias for the machine mode used for memory references to
- functions being called, in `call' RTL expressions. On most
- machines this should be `QImode'.
-
-`INTEGRATE_THRESHOLD (DECL)'
- A C expression for the maximum number of instructions above which
- the function DECL should not be inlined. DECL is a
- `FUNCTION_DECL' node.
-
- The default definition of this macro is 64 plus 8 times the number
- of arguments that the function accepts. Some people think a larger
- threshold should be used on RISC machines.
-
-`STDC_0_IN_SYSTEM_HEADERS'
- In normal operation, the preprocessor expands `__STDC__' to the
- constant 1, to signify that GCC conforms to ISO Standard C. On
- some hosts, like Solaris, the system compiler uses a different
- convention, where `__STDC__' is normally 0, but is 1 if the user
- specifies strict conformance to the C Standard.
-
- Defining `STDC_0_IN_SYSTEM_HEADERS' makes GNU CPP follows the host
- convention when processing system header files, but when
- processing user files `__STDC__' will always expand to 1.
-
-`SCCS_DIRECTIVE'
- Define this if the preprocessor should ignore `#sccs' directives
- and print no error message.
-
-`NO_IMPLICIT_EXTERN_C'
- Define this macro if the system header files support C++ as well
- as C. This macro inhibits the usual method of using system header
- files in C++, which is to pretend that the file's contents are
- enclosed in `extern "C" {...}'.
-
-`HANDLE_PRAGMA (GETC, UNGETC, NAME)'
- This macro is no longer supported. You must use
- `REGISTER_TARGET_PRAGMAS' instead.
-
-`REGISTER_TARGET_PRAGMAS (PFILE)'
- Define this macro if you want to implement any target-specific
- pragmas. If defined, it is a C expression which makes a series of
- calls to `cpp_register_pragma' for each pragma, with PFILE passed
- as the first argument to to these functions. The macro may also
- do any setup required for the pragmas.
-
- The primary reason to define this macro is to provide
- compatibility with other compilers for the same target. In
- general, we discourage definition of target-specific pragmas for
- GCC.
-
- If the pragma can be implemented by attributes then you should
- consider defining the target hook `TARGET_INSERT_ATTRIBUTES' as
- well.
-
- Preprocessor macros that appear on pragma lines are not expanded.
- All `#pragma' directives that do not match any registered pragma
- are silently ignored, unless the user specifies
- `-Wunknown-pragmas'.
-
- - Function: void cpp_register_pragma (cpp_reader *PFILE, const
- char *SPACE, const char *NAME, void (*CALLBACK)
- (cpp_reader *))
- Each call to `cpp_register_pragma' establishes one pragma.
- The CALLBACK routine will be called when the preprocessor
- encounters a pragma of the form
-
- #pragma [SPACE] NAME ...
-
- SPACE is the case-sensitive namespace of the pragma, or
- `NULL' to put the pragma in the global namespace. The
- callback routine receives PFILE as its first argument, which
- can be passed on to cpplib's functions if necessary. You can
- lex tokens after the NAME by calling `c_lex'. Tokens that
- are not read by the callback will be silently ignored. The
- end of the line is indicated by a token of type `CPP_EOF'.
-
- For an example use of this routine, see `c4x.h' and the
- callback routines defined in `c4x-c.c'.
-
- Note that the use of `c_lex' is specific to the C and C++
- compilers. It will not work in the Java or Fortran
- compilers, or any other language compilers for that matter.
- Thus if `c_lex' is going to be called from target-specific
- code, it must only be done so when building the C and C++
- compilers. This can be done by defining the variables
- `c_target_objs' and `cxx_target_objs' in the target entry in
- the `config.gcc' file. These variables should name the
- target-specific, language-specific object file which contains
- the code that uses `c_lex'. Note it will also be necessary
- to add a rule to the makefile fragment pointed to by
- `tmake_file' that shows how to build this object file.
-
-`HANDLE_SYSV_PRAGMA'
- Define this macro (to a value of 1) if you want the System V style
- pragmas `#pragma pack(<n>)' and `#pragma weak <name> [=<value>]'
- to be supported by gcc.
-
- The pack pragma specifies the maximum alignment (in bytes) of
- fields within a structure, in much the same way as the
- `__aligned__' and `__packed__' `__attribute__'s do. A pack value
- of zero resets the behavior to the default.
-
- The weak pragma only works if `SUPPORTS_WEAK' and
- `ASM_WEAKEN_LABEL' are defined. If enabled it allows the creation
- of specifically named weak labels, optionally with a value.
-
-`HANDLE_PRAGMA_PACK_PUSH_POP'
- Define this macro (to a value of 1) if you want to support the
- Win32 style pragmas `#pragma pack(push,N)' and `#pragma
- pack(pop)'. The `pack(push,N)' pragma specifies the maximum
- alignment (in bytes) of fields within a structure, in much the
- same way as the `__aligned__' and `__packed__' `__attribute__'s
- do. A pack value of zero resets the behavior to the default.
- Successive invocations of this pragma cause the previous values to
- be stacked, so that invocations of `#pragma pack(pop)' will return
- to the previous value.
-
-`DOLLARS_IN_IDENTIFIERS'
- Define this macro to control use of the character `$' in identifier
- names. 0 means `$' is not allowed by default; 1 means it is
- allowed. 1 is the default; there is no need to define this macro
- in that case. This macro controls the compiler proper; it does
- not affect the preprocessor.
-
-`NO_DOLLAR_IN_LABEL'
- Define this macro if the assembler does not accept the character
- `$' in label names. By default constructors and destructors in
- G++ have `$' in the identifiers. If this macro is defined, `.' is
- used instead.
-
-`NO_DOT_IN_LABEL'
- Define this macro if the assembler does not accept the character
- `.' in label names. By default constructors and destructors in G++
- have names that use `.'. If this macro is defined, these names
- are rewritten to avoid `.'.
-
-`DEFAULT_MAIN_RETURN'
- Define this macro if the target system expects every program's
- `main' function to return a standard "success" value by default
- (if no other value is explicitly returned).
-
- The definition should be a C statement (sans semicolon) to
- generate the appropriate rtl instructions. It is used only when
- compiling the end of `main'.
-
-`NEED_ATEXIT'
- Define this if the target system lacks the function `atexit' from
- the ISO C standard. If this macro is defined, a default definition
- will be provided to support C++. If `ON_EXIT' is not defined, a
- default `exit' function will also be provided.
-
-`ON_EXIT'
- Define this macro if the target has another way to implement atexit
- functionality without replacing `exit'. For instance, SunOS 4 has
- a similar `on_exit' library function.
-
- The definition should be a functional macro which can be used just
- like the `atexit' function.
-
-`EXIT_BODY'
- Define this if your `exit' function needs to do something besides
- calling an external function `_cleanup' before terminating with
- `_exit'. The `EXIT_BODY' macro is only needed if `NEED_ATEXIT' is
- defined and `ON_EXIT' is not defined.
-
-`INSN_SETS_ARE_DELAYED (INSN)'
- Define this macro as a C expression that is nonzero if it is safe
- for the delay slot scheduler to place instructions in the delay
- slot of INSN, even if they appear to use a resource set or
- clobbered in INSN. INSN is always a `jump_insn' or an `insn'; GCC
- knows that every `call_insn' has this behavior. On machines where
- some `insn' or `jump_insn' is really a function call and hence has
- this behavior, you should define this macro.
-
- You need not define this macro if it would always return zero.
-
-`INSN_REFERENCES_ARE_DELAYED (INSN)'
- Define this macro as a C expression that is nonzero if it is safe
- for the delay slot scheduler to place instructions in the delay
- slot of INSN, even if they appear to set or clobber a resource
- referenced in INSN. INSN is always a `jump_insn' or an `insn'.
- On machines where some `insn' or `jump_insn' is really a function
- call and its operands are registers whose use is actually in the
- subroutine it calls, you should define this macro. Doing so
- allows the delay slot scheduler to move instructions which copy
- arguments into the argument registers into the delay slot of INSN.
-
- You need not define this macro if it would always return zero.
-
-`MACHINE_DEPENDENT_REORG (INSN)'
- In rare cases, correct code generation requires extra machine
- dependent processing between the second jump optimization pass and
- delayed branch scheduling. On those machines, define this macro
- as a C statement to act on the code starting at INSN.
-
-`MULTIPLE_SYMBOL_SPACES'
- Define this macro if in some cases global symbols from one
- translation unit may not be bound to undefined symbols in another
- translation unit without user intervention. For instance, under
- Microsoft Windows symbols must be explicitly imported from shared
- libraries (DLLs).
-
-`MD_ASM_CLOBBERS (CLOBBERS)'
- A C statement that adds to CLOBBERS `STRING_CST' trees for any
- hard regs the port wishes to automatically clobber for all asms.
-
-`MAX_INTEGER_COMPUTATION_MODE'
- Define this to the largest integer machine mode which can be used
- for operations other than load, store and copy operations.
-
- You need only define this macro if the target holds values larger
- than `word_mode' in general purpose registers. Most targets
- should not define this macro.
-
-`MATH_LIBRARY'
- Define this macro as a C string constant for the linker argument
- to link in the system math library, or `""' if the target does not
- have a separate math library.
-
- You need only define this macro if the default of `"-lm"' is wrong.
-
-`LIBRARY_PATH_ENV'
- Define this macro as a C string constant for the environment
- variable that specifies where the linker should look for libraries.
-
- You need only define this macro if the default of `"LIBRARY_PATH"'
- is wrong.
-
-`TARGET_HAS_F_SETLKW'
- Define this macro if the target supports file locking with fcntl /
- F_SETLKW. Note that this functionality is part of POSIX.
- Defining `TARGET_HAS_F_SETLKW' will enable the test coverage code
- to use file locking when exiting a program, which avoids race
- conditions if the program has forked.
-
-`MAX_CONDITIONAL_EXECUTE'
- A C expression for the maximum number of instructions to execute
- via conditional execution instructions instead of a branch. A
- value of `BRANCH_COST'+1 is the default if the machine does not
- use cc0, and 1 if it does use cc0.
-
-`IFCVT_MODIFY_TESTS'
- A C expression to modify the tests in `TRUE_EXPR', and
- `FALSE_EXPR' for use in converting insns in `TEST_BB', `THEN_BB',
- `ELSE_BB', and `JOIN_BB' basic blocks to conditional execution.
- Set either `TRUE_EXPR' or `FALSE_EXPR' to a null pointer if the
- tests cannot be converted.
-
-`IFCVT_MODIFY_INSN'
- A C expression to modify the `PATTERN' of an `INSN' that is to be
- converted to conditional execution format.
-
-`IFCVT_MODIFY_FINAL'
- A C expression to perform any final machine dependent
- modifications in converting code to conditional execution in the
- basic blocks `TEST_BB', `THEN_BB', `ELSE_BB', and `JOIN_BB'.
-
-`IFCVT_MODIFY_CANCEL'
- A C expression to cancel any machine dependent modifications in
- converting code to conditional execution in the basic blocks
- `TEST_BB', `THEN_BB', `ELSE_BB', and `JOIN_BB'.
-
- - Target Hook: void TARGET_INIT_BUILTINS ()
- Define this hook if you have any machine-specific built-in
- functions that need to be defined. It should be a function that
- performs the necessary setup.
-
- Machine specific built-in functions can be useful to expand
- special machine instructions that would otherwise not normally be
- generated because they have no equivalent in the source language
- (for example, SIMD vector instructions or prefetch instructions).
-
- To create a built-in function, call the function `builtin_function'
- which is defined by the language front end. You can use any type
- nodes set up by `build_common_tree_nodes' and
- `build_common_tree_nodes_2'; only language front ends that use
- those two functions will call `TARGET_INIT_BUILTINS'.
-
- - Target Hook: rtx TARGET_EXPAND_BUILTIN (tree EXP, rtx TARGET, rtx
- SUBTARGET, enum machine_mode MODE, int IGNORE)
- Expand a call to a machine specific built-in function that was set
- up by `TARGET_INIT_BUILTINS'. EXP is the expression for the
- function call; the result should go to TARGET if that is
- convenient, and have mode MODE if that is convenient. SUBTARGET
- may be used as the target for computing one of EXP's operands.
- IGNORE is nonzero if the value is to be ignored. This function
- should return the result of the call to the built-in function.
-
-`MD_CAN_REDIRECT_BRANCH(BRANCH1, BRANCH2)'
- Take a branch insn in BRANCH1 and another in BRANCH2. Return true
- if redirecting BRANCH1 to the destination of BRANCH2 is possible.
-
- On some targets, branches may have a limited range. Optimizing the
- filling of delay slots can result in branches being redirected,
- and this may in turn cause a branch offset to overflow.
-
-`ALLOCATE_INITIAL_VALUE(HARD_REG)'
- When the initial value of a hard register has been copied in a
- pseudo register, it is often not necessary to actually allocate
- another register to this pseudo register, because the original
- hard register or a stack slot it has been saved into can be used.
- `ALLOCATE_INITIAL_VALUE', if defined, is called at the start of
- register allocation once for each hard register that had its
- initial value copied by using `get_func_hard_reg_initial_val' or
- `get_hard_reg_initial_val'. Possible values are `NULL_RTX', if
- you don't want to do any special allocation, a `REG' rtx--that
- would typically be the hard register itself, if it is known not to
- be clobbered--or a `MEM'. If you are returning a `MEM', this is
- only a hint for the allocator; it might decide to use another
- register anyways. You may use `current_function_leaf_function' in
- the definition of the macro, functions that use `REG_N_SETS', to
- determine if the hard register in question will not be clobbered.
-
-`TARGET_OBJECT_SUFFIX'
- Define this macro to be a C string representing the suffix for
- object files on your target machine. If you do not define this
- macro, GCC will use `.o' as the suffix for object files.
-
-`TARGET_EXECUTABLE_SUFFIX'
- Define this macro to be a C string representing the suffix to be
- automatically added to executable files on your target machine.
- If you do not define this macro, GCC will use the null string as
- the suffix for executable files.
-
-`COLLECT_EXPORT_LIST'
- If defined, `collect2' will scan the individual object files
- specified on its command line and create an export list for the
- linker. Define this macro for systems like AIX, where the linker
- discards object files that are not referenced from `main' and uses
- export lists.
-
-
- - Target Hook: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
- This target hook returns `true' past the point in which new jump
- instructions could be created. On machines that require a
- register for every jump such as the SHmedia ISA of SH5, this point
- would typically be reload, so this target hook should be defined
- to a function such as:
-
- static bool
- cannot_modify_jumps_past_reload_p ()
- {
- return (reload_completed || reload_in_progress);
- }
-
-\1f
-File: gccint.info, Node: Host Config, Next: Fragments, Prev: Target Macros, Up: Top
-
-Host Configuration Headers
-**************************
-
- Host configuration headers contain macro definitions that describe
-the machine and system on which the compiler is running. They are
-usually unnecessary. Most of the things GCC needs to know about the
-host system can be deduced by the `configure' script.
-
- If your host does need a special configuration header, it should be
-named `xm-MACHINE.h', where MACHINE is a short mnemonic for the
-machine. Here are some macros which this header can define.
-
-`VMS'
- Define this macro if the host system is VMS.
-
-`FATAL_EXIT_CODE'
- A C expression for the status code to be returned when the compiler
- exits after serious errors. The default is the system-provided
- macro `EXIT_FAILURE', or `1' if the system doesn't define that
- macro. Define this macro only if these defaults are incorrect.
-
-`SUCCESS_EXIT_CODE'
- A C expression for the status code to be returned when the compiler
- exits without serious errors. (Warnings are not serious errors.)
- The default is the system-provided macro `EXIT_SUCCESS', or `0' if
- the system doesn't define that macro. Define this macro only if
- these defaults are incorrect.
-
-`USE_C_ALLOCA'
- Define this macro if GCC should use the C implementation of
- `alloca' provided by `libiberty.a'. This only affects how some
- parts of the compiler itself allocate memory. It does not change
- code generation.
-
- When GCC is built with a compiler other than itself, the C `alloca'
- is always used. This is because most other implementations have
- serious bugs. You should define this macro only on a system where
- no stack-based `alloca' can possibly work. For instance, if a
- system has a small limit on the size of the stack, GCC's builtin
- `alloca' will not work reliably.
-
-`HAVE_DOS_BASED_FILE_SYSTEM'
- Define this macro if the host file system obeys the semantics
- defined by MS-DOS instead of Unix. DOS file systems are case
- insensitive, file specifications may begin with a drive letter,
- and both forward slash and backslash (`/' and `\') are directory
- separators. If you define this macro, you probably need to define
- the next three macros too.
-
-`PATH_SEPARATOR'
- If defined, this macro should expand to a character constant
- specifying the separator for elements of search paths. The
- default value is a colon (`:'). DOS-based systems usually use
- semicolon (`;').
-
-`DIR_SEPARATOR'
-`DIR_SEPARATOR_2'
- If defined, these macros expand to character constants specifying
- separators for directory names within a file specification. They
- are used somewhat inconsistently throughout the compiler. If your
- system behaves like Unix (only forward slash separates pathnames),
- define neither of them. If your system behaves like DOS (both
- forward and backward slash can be used), define `DIR_SEPARATOR' to
- `/' and `DIR_SEPARATOR_2' to `\'.
-
-`HOST_OBJECT_SUFFIX'
- Define this macro to be a C string representing the suffix for
- object files on your host machine. If you do not define this
- macro, GCC will use `.o' as the suffix for object files.
-
-`HOST_EXECUTABLE_SUFFIX'
- Define this macro to be a C string representing the suffix for
- executable files on your host machine. If you do not define this
- macro, GCC will use the null string as the suffix for executable
- files.
-
-`HOST_BIT_BUCKET'
- A pathname defined by the host operating system, which can be
- opened as a file and written to, but all the information written
- is discarded. This is commonly known as a "bit bucket" or "null
- device". If you do not define this macro, GCC will use
- `/dev/null' as the bit bucket. If the host does not support a bit
- bucket, define this macro to an invalid filename.
-
-`COLLECT2_HOST_INITIALIZATION'
- If defined, a C statement (sans semicolon) that performs
- host-dependent initialization when `collect2' is being initialized.
-
-`GCC_DRIVER_HOST_INITIALIZATION'
- If defined, a C statement (sans semicolon) that performs
- host-dependent initialization when a compilation driver is being
- initialized.
-
-`UPDATE_PATH_HOST_CANONICALIZE (PATH)'
- If defined, a C statement (sans semicolon) that performs
- host-dependent canonicalization when a path used in a compilation
- driver or preprocessor is canonicalized. PATH is a malloc-ed path
- to be canonicalized. If the C statement does canonicalize PATH
- into a different buffer, the old path should be freed and the new
- buffer should have been allocated with malloc.
-
-`DUMPFILE_FORMAT'
- Define this macro to be a C string representing the format to use
- for constructing the index part of debugging dump file names. The
- resultant string must fit in fifteen bytes. The full filename
- will be the concatenation of: the prefix of the assembler file
- name, the string resulting from applying this format to an index
- number, and a string unique to each dump file kind, e.g. `rtl'.
-
- If you do not define this macro, GCC will use `.%02d.'. You should
- define this macro if using the default will create an invalid file
- name.
-
-`SMALL_ARG_MAX'
- Define this macro if the host system has a small limit on the total
- size of an argument vector. This causes the driver to take more
- care not to pass unnecessary arguments to subprocesses.
-
- In addition, if `configure' generates an incorrect definition of any
-of the macros in `auto-host.h', you can override that definition in a
-host configuration header. If you need to do this, first see if it is
-possible to fix `configure'.
-
- If you need to define only a few of these macros, and they have
-simple definitions, consider using the `xm_defines' variable in your
-`config.gcc' entry instead of creating a host configuration header.
-*Note System Config::.
-
-\1f
-File: gccint.info, Node: Fragments, Next: Collect2, Prev: Host Config, Up: Top
-
-Makefile Fragments
-******************
-
- When you configure GCC using the `configure' script, it will
-construct the file `Makefile' from the template file `Makefile.in'.
-When it does this, it can incorporate makefile fragments from the
-`config' directory. These are used to set Makefile parameters that are
-not amenable to being calculated by autoconf. The list of fragments to
-incorporate is set by `config.gcc'; *Note System Config::.
-
- Fragments are named either `t-TARGET' or `x-HOST', depending on
-whether they are relevant to configuring GCC to produce code for a
-particular target, or to configuring GCC to run on a particular host.
-Here TARGET and HOST are mnemonics which usually have some relationship
-to the canonical system name, but no formal connection.
-
- If these files do not exist, it means nothing needs to be added for a
-given target or host. Most targets need a few `t-TARGET' fragments,
-but needing `x-HOST' fragments is rare.
-
-* Menu:
-
-* Target Fragment:: Writing `t-TARGET' files.
-* Host Fragment:: Writing `x-HOST' files.
-
-\1f
-File: gccint.info, Node: Target Fragment, Next: Host Fragment, Up: Fragments
-
-Target Makefile Fragments
-=========================
-
- Target makefile fragments can set these Makefile variables.
-
-`LIBGCC2_CFLAGS'
- Compiler flags to use when compiling `libgcc2.c'.
-
-`LIB2FUNCS_EXTRA'
- A list of source file names to be compiled or assembled and
- inserted into `libgcc.a'.
-
-`Floating Point Emulation'
- To have GCC include software floating point libraries in `libgcc.a'
- define `FPBIT' and `DPBIT' along with a few rules as follows:
- # We want fine grained libraries, so use the new code
- # to build the floating point emulation libraries.
- FPBIT = fp-bit.c
- DPBIT = dp-bit.c
-
-
- fp-bit.c: $(srcdir)/config/fp-bit.c
- echo '#define FLOAT' > fp-bit.c
- cat $(srcdir)/config/fp-bit.c >> fp-bit.c
-
- dp-bit.c: $(srcdir)/config/fp-bit.c
- cat $(srcdir)/config/fp-bit.c > dp-bit.c
-
- You may need to provide additional #defines at the beginning of
- `fp-bit.c' and `dp-bit.c' to control target endianness and other
- options.
-
-`CRTSTUFF_T_CFLAGS'
- Special flags used when compiling `crtstuff.c'. *Note
- Initialization::.
-
-`CRTSTUFF_T_CFLAGS_S'
- Special flags used when compiling `crtstuff.c' for shared linking.
- Used if you use `crtbeginS.o' and `crtendS.o' in `EXTRA-PARTS'.
- *Note Initialization::.
-
-`MULTILIB_OPTIONS'
- For some targets, invoking GCC in different ways produces objects
- that can not be linked together. For example, for some targets GCC
- produces both big and little endian code. For these targets, you
- must arrange for multiple versions of `libgcc.a' to be compiled,
- one for each set of incompatible options. When GCC invokes the
- linker, it arranges to link in the right version of `libgcc.a',
- based on the command line options used.
-
- The `MULTILIB_OPTIONS' macro lists the set of options for which
- special versions of `libgcc.a' must be built. Write options that
- are mutually incompatible side by side, separated by a slash.
- Write options that may be used together separated by a space. The
- build procedure will build all combinations of compatible options.
-
- For example, if you set `MULTILIB_OPTIONS' to `m68000/m68020
- msoft-float', `Makefile' will build special versions of `libgcc.a'
- using the following sets of options: `-m68000', `-m68020',
- `-msoft-float', `-m68000 -msoft-float', and `-m68020 -msoft-float'.
-
-`MULTILIB_DIRNAMES'
- If `MULTILIB_OPTIONS' is used, this variable specifies the
- directory names that should be used to hold the various libraries.
- Write one element in `MULTILIB_DIRNAMES' for each element in
- `MULTILIB_OPTIONS'. If `MULTILIB_DIRNAMES' is not used, the
- default value will be `MULTILIB_OPTIONS', with all slashes treated
- as spaces.
-
- For example, if `MULTILIB_OPTIONS' is set to `m68000/m68020
- msoft-float', then the default value of `MULTILIB_DIRNAMES' is
- `m68000 m68020 msoft-float'. You may specify a different value if
- you desire a different set of directory names.
-
-`MULTILIB_MATCHES'
- Sometimes the same option may be written in two different ways.
- If an option is listed in `MULTILIB_OPTIONS', GCC needs to know
- about any synonyms. In that case, set `MULTILIB_MATCHES' to a
- list of items of the form `option=option' to describe all relevant
- synonyms. For example, `m68000=mc68000 m68020=mc68020'.
-
-`MULTILIB_EXCEPTIONS'
- Sometimes when there are multiple sets of `MULTILIB_OPTIONS' being
- specified, there are combinations that should not be built. In
- that case, set `MULTILIB_EXCEPTIONS' to be all of the switch
- exceptions in shell case syntax that should not be built.
-
- For example, in the PowerPC embedded ABI support, it is not
- desirable to build libraries compiled with the `-mcall-aix' option
- and either of the `-fleading-underscore' or `-mlittle' options at
- the same time. Therefore `MULTILIB_EXCEPTIONS' is set to
- *mcall-aix/*fleading-underscore* *mlittle/*mcall-aix*
-
-`MULTILIB_EXTRA_OPTS'
- Sometimes it is desirable that when building multiple versions of
- `libgcc.a' certain options should always be passed on to the
- compiler. In that case, set `MULTILIB_EXTRA_OPTS' to be the list
- of options to be used for all builds.
-
-\1f
-File: gccint.info, Node: Host Fragment, Prev: Target Fragment, Up: Fragments
-
-Host Makefile Fragments
-=======================
-
- The use of `x-HOST' fragments is discouraged. You should do so only
-if there is no other mechanism to get the behavior desired. Host
-fragments should never forcibly override variables set by the configure
-script, as they may have been adjusted by the user.
-
- Variables provided for host fragments to set include:
-
-`X_CFLAGS'
-`X_CPPFLAGS'
- These are extra flags to pass to the C compiler and preprocessor,
- respectively. They are used both when building GCC, and when
- compiling things with the just-built GCC.
-
-`XCFLAGS'
- These are extra flags to use when building the compiler. They are
- not used when compiling `libgcc.a'. However, they _are_ used when
- recompiling the compiler with itself in later stages of a
- bootstrap.
-
-`BOOT_LDFLAGS'
- Flags to be passed to the linker when recompiling the compiler with
- itself in later stages of a bootstrap. You might need to use this
- if, for instance, one of the front ends needs more text space than
- the linker provides by default.
-
-`EXTRA_PROGRAMS'
- A list of additional programs required to use the compiler on this
- host, which should be compiled with GCC and installed alongside
- the front ends. If you set this variable, you must also provide
- rules to build the extra programs.
-
-
-\1f
-File: gccint.info, Node: Collect2, Next: Header Dirs, Prev: Fragments, Up: Top
-
-`collect2'
-**********
-
- GNU CC uses a utility called `collect2' on nearly all systems to
-arrange to call various initialization functions at start time.
-
- The program `collect2' works by linking the program once and looking
-through the linker output file for symbols with particular names
-indicating they are constructor functions. If it finds any, it creates
-a new temporary `.c' file containing a table of them, compiles it, and
-links the program a second time including that file.
-
- The actual calls to the constructors are carried out by a subroutine
-called `__main', which is called (automatically) at the beginning of
-the body of `main' (provided `main' was compiled with GNU CC). Calling
-`__main' is necessary, even when compiling C code, to allow linking C
-and C++ object code together. (If you use `-nostdlib', you get an
-unresolved reference to `__main', since it's defined in the standard
-GCC library. Include `-lgcc' at the end of your compiler command line
-to resolve this reference.)
-
- The program `collect2' is installed as `ld' in the directory where
-the passes of the compiler are installed. When `collect2' needs to
-find the _real_ `ld', it tries the following file names:
-
- * `real-ld' in the directories listed in the compiler's search
- directories.
-
- * `real-ld' in the directories listed in the environment variable
- `PATH'.
-
- * The file specified in the `REAL_LD_FILE_NAME' configuration macro,
- if specified.
-
- * `ld' in the compiler's search directories, except that `collect2'
- will not execute itself recursively.
-
- * `ld' in `PATH'.
-
- "The compiler's search directories" means all the directories where
-`gcc' searches for passes of the compiler. This includes directories
-that you specify with `-B'.
-
- Cross-compilers search a little differently:
-
- * `real-ld' in the compiler's search directories.
-
- * `TARGET-real-ld' in `PATH'.
-
- * The file specified in the `REAL_LD_FILE_NAME' configuration macro,
- if specified.
-
- * `ld' in the compiler's search directories.
-
- * `TARGET-ld' in `PATH'.
-
- `collect2' explicitly avoids running `ld' using the file name under
-which `collect2' itself was invoked. In fact, it remembers up a list
-of such names--in case one copy of `collect2' finds another copy (or
-version) of `collect2' installed as `ld' in a second place in the
-search path.
-
- `collect2' searches for the utilities `nm' and `strip' using the
-same algorithm as above for `ld'.
-
-\1f
-File: gccint.info, Node: Header Dirs, Next: Funding, Prev: Collect2, Up: Top
-
-Standard Header File Directories
-********************************
-
- `GCC_INCLUDE_DIR' means the same thing for native and cross. It is
-where GNU CC stores its private include files, and also where GNU CC
-stores the fixed include files. A cross compiled GNU CC runs
-`fixincludes' on the header files in `$(tooldir)/include'. (If the
-cross compilation header files need to be fixed, they must be installed
-before GNU CC is built. If the cross compilation header files are
-already suitable for ISO C and GNU CC, nothing special need be done).
-
- `GPLUSPLUS_INCLUDE_DIR' means the same thing for native and cross.
-It is where `g++' looks first for header files. The C++ library
-installs only target independent header files in that directory.
-
- `LOCAL_INCLUDE_DIR' is used only by native compilers. GNU CC
-doesn't install anything there. It is normally `/usr/local/include'.
-This is where local additions to a packaged system should place header
-files.
-
- `CROSS_INCLUDE_DIR' is used only by cross compilers. GNU CC doesn't
-install anything there.
-
- `TOOL_INCLUDE_DIR' is used for both native and cross compilers. It
-is the place for other packages to install header files that GNU CC will
-use. For a cross-compiler, this is the equivalent of `/usr/include'.
-When you build a cross-compiler, `fixincludes' processes any header
-files in this directory.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Funding, Next: GNU Project, Prev: Header Dirs, Up: Top
-
-Funding Free Software
-*********************
-
- If you want to have more free software a few years from now, it makes
-sense for you to help encourage people to contribute funds for its
-development. The most effective approach known is to encourage
-commercial redistributors to donate.
-
- Users of free software systems can boost the pace of development by
-encouraging for-a-fee distributors to donate part of their selling price
-to free software developers--the Free Software Foundation, and others.
-
- The way to convince distributors to do this is to demand it and
-expect it from them. So when you compare distributors, judge them
-partly by how much they give to free software development. Show
-distributors they must compete to be the one who gives the most.
-
- To make this approach work, you must insist on numbers that you can
-compare, such as, "We will donate ten dollars to the Frobnitz project
-for each disk sold." Don't be satisfied with a vague promise, such as
-"A portion of the profits are donated," since it doesn't give a basis
-for comparison.
-
- Even a precise fraction "of the profits from this disk" is not very
-meaningful, since creative accounting and unrelated business decisions
-can greatly alter what fraction of the sales price counts as profit.
-If the price you pay is $50, ten percent of the profit is probably less
-than a dollar; it might be a few cents, or nothing at all.
-
- Some redistributors do development work themselves. This is useful
-too; but to keep everyone honest, you need to inquire how much they do,
-and what kind. Some kinds of development make much more long-term
-difference than others. For example, maintaining a separate version of
-a program contributes very little; maintaining the standard version of a
-program for the whole community contributes much. Easy new ports
-contribute little, since someone else would surely do them; difficult
-ports such as adding a new CPU to the GNU Compiler Collection
-contribute more; major new features or packages contribute the most.
-
- By establishing the idea that supporting further development is "the
-proper thing to do" when distributing free software for a fee, we can
-assure a steady flow of resources into making more free software.
-
- Copyright (C) 1994 Free Software Foundation, Inc.
- Verbatim copying and redistribution of this section is permitted
- without royalty; alteration is not permitted.
-
-\1f
-File: gccint.info, Node: GNU Project, Next: Copying, Prev: Funding, Up: Top
-
-The GNU Project and GNU/Linux
-*****************************
-
- The GNU Project was launched in 1984 to develop a complete Unix-like
-operating system which is free software: the GNU system. (GNU is a
-recursive acronym for "GNU's Not Unix"; it is pronounced "guh-NEW".)
-Variants of the GNU operating system, which use the kernel Linux, are
-now widely used; though these systems are often referred to as "Linux",
-they are more accurately called GNU/Linux systems.
-
- For more information, see:
- `http://www.gnu.org/'
- `http://www.gnu.org/gnu/linux-and-gnu.html'
-
-\1f
-File: gccint.info, Node: Copying, Next: GNU Free Documentation License, Prev: GNU Project, Up: Top
-
-GNU GENERAL PUBLIC LICENSE
-**************************
-
- Version 2, June 1991
- Copyright (C) 1989, 1991 Free Software Foundation, Inc.
- 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
-
- Everyone is permitted to copy and distribute verbatim copies
- of this license document, but changing it is not allowed.
-
-Preamble
-========
-
- The licenses for most software are designed to take away your
-freedom to share and change it. By contrast, the GNU General Public
-License is intended to guarantee your freedom to share and change free
-software--to make sure the software is free for all its users. This
-General Public License applies to most of the Free Software
-Foundation's software and to any other program whose authors commit to
-using it. (Some other Free Software Foundation software is covered by
-the GNU Library General Public License instead.) You can apply it to
-your programs, too.
-
- When we speak of free software, we are referring to freedom, not
-price. Our General Public Licenses are designed to make sure that you
-have the freedom to distribute copies of free software (and charge for
-this service if you wish), that you receive source code or can get it
-if you want it, that you can change the software or use pieces of it in
-new free programs; and that you know you can do these things.
-
- To protect your rights, we need to make restrictions that forbid
-anyone to deny you these rights or to ask you to surrender the rights.
-These restrictions translate to certain responsibilities for you if you
-distribute copies of the software, or if you modify it.
-
- For example, if you distribute copies of such a program, whether
-gratis or for a fee, you must give the recipients all the rights that
-you have. You must make sure that they, too, receive or can get the
-source code. And you must show them these terms so they know their
-rights.
-
- We protect your rights with two steps: (1) copyright the software,
-and (2) offer you this license which gives you legal permission to copy,
-distribute and/or modify the software.
-
- Also, for each author's protection and ours, we want to make certain
-that everyone understands that there is no warranty for this free
-software. If the software is modified by someone else and passed on, we
-want its recipients to know that what they have is not the original, so
-that any problems introduced by others will not reflect on the original
-authors' reputations.
-
- Finally, any free program is threatened constantly by software
-patents. We wish to avoid the danger that redistributors of a free
-program will individually obtain patent licenses, in effect making the
-program proprietary. To prevent this, we have made it clear that any
-patent must be licensed for everyone's free use or not licensed at all.
-
- The precise terms and conditions for copying, distribution and
-modification follow.
-
- TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
- 0. This License applies to any program or other work which contains a
- notice placed by the copyright holder saying it may be distributed
- under the terms of this General Public License. The "Program",
- below, refers to any such program or work, and a "work based on
- the Program" means either the Program or any derivative work under
- copyright law: that is to say, a work containing the Program or a
- portion of it, either verbatim or with modifications and/or
- translated into another language. (Hereinafter, translation is
- included without limitation in the term "modification".) Each
- licensee is addressed as "you".
-
- Activities other than copying, distribution and modification are
- not covered by this License; they are outside its scope. The act
- of running the Program is not restricted, and the output from the
- Program is covered only if its contents constitute a work based on
- the Program (independent of having been made by running the
- Program). Whether that is true depends on what the Program does.
-
- 1. You may copy and distribute verbatim copies of the Program's
- source code as you receive it, in any medium, provided that you
- conspicuously and appropriately publish on each copy an appropriate
- copyright notice and disclaimer of warranty; keep intact all the
- notices that refer to this License and to the absence of any
- warranty; and give any other recipients of the Program a copy of
- this License along with the Program.
-
- You may charge a fee for the physical act of transferring a copy,
- and you may at your option offer warranty protection in exchange
- for a fee.
-
- 2. You may modify your copy or copies of the Program or any portion
- of it, thus forming a work based on the Program, and copy and
- distribute such modifications or work under the terms of Section 1
- above, provided that you also meet all of these conditions:
-
- a. You must cause the modified files to carry prominent notices
- stating that you changed the files and the date of any change.
-
- b. You must cause any work that you distribute or publish, that
- in whole or in part contains or is derived from the Program
- or any part thereof, to be licensed as a whole at no charge
- to all third parties under the terms of this License.
-
- c. If the modified program normally reads commands interactively
- when run, you must cause it, when started running for such
- interactive use in the most ordinary way, to print or display
- an announcement including an appropriate copyright notice and
- a notice that there is no warranty (or else, saying that you
- provide a warranty) and that users may redistribute the
- program under these conditions, and telling the user how to
- view a copy of this License. (Exception: if the Program
- itself is interactive but does not normally print such an
- announcement, your work based on the Program is not required
- to print an announcement.)
-
- These requirements apply to the modified work as a whole. If
- identifiable sections of that work are not derived from the
- Program, and can be reasonably considered independent and separate
- works in themselves, then this License, and its terms, do not
- apply to those sections when you distribute them as separate
- works. But when you distribute the same sections as part of a
- whole which is a work based on the Program, the distribution of
- the whole must be on the terms of this License, whose permissions
- for other licensees extend to the entire whole, and thus to each
- and every part regardless of who wrote it.
-
- Thus, it is not the intent of this section to claim rights or
- contest your rights to work written entirely by you; rather, the
- intent is to exercise the right to control the distribution of
- derivative or collective works based on the Program.
-
- In addition, mere aggregation of another work not based on the
- Program with the Program (or with a work based on the Program) on
- a volume of a storage or distribution medium does not bring the
- other work under the scope of this License.
-
- 3. You may copy and distribute the Program (or a work based on it,
- under Section 2) in object code or executable form under the terms
- of Sections 1 and 2 above provided that you also do one of the
- following:
-
- a. Accompany it with the complete corresponding machine-readable
- source code, which must be distributed under the terms of
- Sections 1 and 2 above on a medium customarily used for
- software interchange; or,
-
- b. Accompany it with a written offer, valid for at least three
- years, to give any third party, for a charge no more than your
- cost of physically performing source distribution, a complete
- machine-readable copy of the corresponding source code, to be
- distributed under the terms of Sections 1 and 2 above on a
- medium customarily used for software interchange; or,
-
- c. Accompany it with the information you received as to the offer
- to distribute corresponding source code. (This alternative is
- allowed only for noncommercial distribution and only if you
- received the program in object code or executable form with
- such an offer, in accord with Subsection b above.)
-
- The source code for a work means the preferred form of the work for
- making modifications to it. For an executable work, complete
- source code means all the source code for all modules it contains,
- plus any associated interface definition files, plus the scripts
- used to control compilation and installation of the executable.
- However, as a special exception, the source code distributed need
- not include anything that is normally distributed (in either
- source or binary form) with the major components (compiler,
- kernel, and so on) of the operating system on which the executable
- runs, unless that component itself accompanies the executable.
-
- If distribution of executable or object code is made by offering
- access to copy from a designated place, then offering equivalent
- access to copy the source code from the same place counts as
- distribution of the source code, even though third parties are not
- compelled to copy the source along with the object code.
-
- 4. You may not copy, modify, sublicense, or distribute the Program
- except as expressly provided under this License. Any attempt
- otherwise to copy, modify, sublicense or distribute the Program is
- void, and will automatically terminate your rights under this
- License. However, parties who have received copies, or rights,
- from you under this License will not have their licenses
- terminated so long as such parties remain in full compliance.
-
- 5. You are not required to accept this License, since you have not
- signed it. However, nothing else grants you permission to modify
- or distribute the Program or its derivative works. These actions
- are prohibited by law if you do not accept this License.
- Therefore, by modifying or distributing the Program (or any work
- based on the Program), you indicate your acceptance of this
- License to do so, and all its terms and conditions for copying,
- distributing or modifying the Program or works based on it.
-
- 6. Each time you redistribute the Program (or any work based on the
- Program), the recipient automatically receives a license from the
- original licensor to copy, distribute or modify the Program
- subject to these terms and conditions. You may not impose any
- further restrictions on the recipients' exercise of the rights
- granted herein. You are not responsible for enforcing compliance
- by third parties to this License.
-
- 7. If, as a consequence of a court judgment or allegation of patent
- infringement or for any other reason (not limited to patent
- issues), conditions are imposed on you (whether by court order,
- agreement or otherwise) that contradict the conditions of this
- License, they do not excuse you from the conditions of this
- License. If you cannot distribute so as to satisfy simultaneously
- your obligations under this License and any other pertinent
- obligations, then as a consequence you may not distribute the
- Program at all. For example, if a patent license would not permit
- royalty-free redistribution of the Program by all those who
- receive copies directly or indirectly through you, then the only
- way you could satisfy both it and this License would be to refrain
- entirely from distribution of the Program.
-
- If any portion of this section is held invalid or unenforceable
- under any particular circumstance, the balance of the section is
- intended to apply and the section as a whole is intended to apply
- in other circumstances.
-
- It is not the purpose of this section to induce you to infringe any
- patents or other property right claims or to contest validity of
- any such claims; this section has the sole purpose of protecting
- the integrity of the free software distribution system, which is
- implemented by public license practices. Many people have made
- generous contributions to the wide range of software distributed
- through that system in reliance on consistent application of that
- system; it is up to the author/donor to decide if he or she is
- willing to distribute software through any other system and a
- licensee cannot impose that choice.
-
- This section is intended to make thoroughly clear what is believed
- to be a consequence of the rest of this License.
-
- 8. If the distribution and/or use of the Program is restricted in
- certain countries either by patents or by copyrighted interfaces,
- the original copyright holder who places the Program under this
- License may add an explicit geographical distribution limitation
- excluding those countries, so that distribution is permitted only
- in or among countries not thus excluded. In such case, this
- License incorporates the limitation as if written in the body of
- this License.
-
- 9. The Free Software Foundation may publish revised and/or new
- versions of the General Public License from time to time. Such
- new versions will be similar in spirit to the present version, but
- may differ in detail to address new problems or concerns.
-
- Each version is given a distinguishing version number. If the
- Program specifies a version number of this License which applies
- to it and "any later version", you have the option of following
- the terms and conditions either of that version or of any later
- version published by the Free Software Foundation. If the Program
- does not specify a version number of this License, you may choose
- any version ever published by the Free Software Foundation.
-
- 10. If you wish to incorporate parts of the Program into other free
- programs whose distribution conditions are different, write to the
- author to ask for permission. For software which is copyrighted
- by the Free Software Foundation, write to the Free Software
- Foundation; we sometimes make exceptions for this. Our decision
- will be guided by the two goals of preserving the free status of
- all derivatives of our free software and of promoting the sharing
- and reuse of software generally.
-
- NO WARRANTY
-
- 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
- WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
- LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
- HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT
- WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT
- NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
- FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE
- QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
- PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
- SERVICING, REPAIR OR CORRECTION.
-
- 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
- WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
- MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
- LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
- INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
- INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
- DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
- OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY
- OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
- ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
-
- END OF TERMS AND CONDITIONS
-
-How to Apply These Terms to Your New Programs
-=============================================
-
- If you develop a new program, and you want it to be of the greatest
-possible use to the public, the best way to achieve this is to make it
-free software which everyone can redistribute and change under these
-terms.
-
- To do so, attach the following notices to the program. It is safest
-to attach them to the start of each source file to most effectively
-convey the exclusion of warranty; and each file should have at least
-the "copyright" line and a pointer to where the full notice is found.
-
- ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
- Copyright (C) YEAR NAME OF AUTHOR
-
- This program is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
- (at your option) any later version.
-
- This program is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software
- Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA.
-
- Also add information on how to contact you by electronic and paper
-mail.
-
- If the program is interactive, make it output a short notice like
-this when it starts in an interactive mode:
-
- Gnomovision version 69, Copyright (C) YEAR NAME OF AUTHOR
- Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
- type `show w'.
- This is free software, and you are welcome to redistribute it
- under certain conditions; type `show c' for details.
-
- The hypothetical commands `show w' and `show c' should show the
-appropriate parts of the General Public License. Of course, the
-commands you use may be called something other than `show w' and `show
-c'; they could even be mouse-clicks or menu items--whatever suits your
-program.
-
- You should also get your employer (if you work as a programmer) or
-your school, if any, to sign a "copyright disclaimer" for the program,
-if necessary. Here is a sample; alter the names:
-
- Yoyodyne, Inc., hereby disclaims all copyright interest in the program
- `Gnomovision' (which makes passes at compilers) written by James Hacker.
-
- SIGNATURE OF TY COON, 1 April 1989
- Ty Coon, President of Vice
-
- This General Public License does not permit incorporating your
-program into proprietary programs. If your program is a subroutine
-library, you may consider it more useful to permit linking proprietary
-applications with the library. If this is what you want to do, use the
-GNU Library General Public License instead of this License.
-
-\1f
-File: gccint.info, Node: GNU Free Documentation License, Next: Contributors, Prev: Copying, Up: Top
-
-GNU Free Documentation License
-******************************
-
- Version 1.1, March 2000
- Copyright (C) 2000 Free Software Foundation, Inc.
- 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
-
- Everyone is permitted to copy and distribute verbatim copies
- of this license document, but changing it is not allowed.
-
- 0. PREAMBLE
-
- The purpose of this License is to make a manual, textbook, or other
- written document "free" in the sense of freedom: to assure everyone
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-ADDENDUM: How to use this License for your documents
-====================================================
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- A copy of the license is included in the section entitled ``GNU
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+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
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- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
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-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
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- A GNU Manual
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- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Contributors, Next: Option Index, Prev: GNU Free Documentation License, Up: Top
-
-Contributors to GCC
-*******************
-
- The GCC project would like to thank its many contributors. Without
-them the project would not have been nearly as successful as it has
-been. Any omissions in this list are accidental. Feel free to contact
-<law@redhat.com> if you have been left out or some of your
-contributions are not listed. Please keep this list in alphabetical
-order.
-
- * Analog Devices helped implement the support for complex data types
- and iterators.
-
- * John David Anglin for threading-related fixes and improvements to
- libstdc++-v3, and the HP-UX port.
-
- * James van Artsdalen wrote the code that makes efficient use of the
- Intel 80387 register stack.
-
- * Alasdair Baird for various bugfixes.
-
- * Gerald Baumgartner added the signature extension to the C++ front
- end.
-
- * Godmar Back for his Java improvements and encouragement.
-
- * Scott Bambrough for help porting the Java compiler.
-
- * Jon Beniston for his Win32 port of Java.
-
- * Geoff Berry for his Java object serialization work and various
- patches.
-
- * Eric Blake for helping to make GCJ and libgcj conform to the
- specifications.
-
- * Hans-J. Boehm for his garbage collector, IA-64 libffi port, and
- other Java work.
-
- * Neil Booth for work on cpplib, lang hooks, debug hooks and other
- miscellaneous clean-ups.
-
- * Per Bothner for his direction via the steering committee and
- various improvements to our infrastructure for supporting new
- languages. Chill front end implementation. Initial
- implementations of cpplib, fix-header, config.guess, libio, and
- past C++ library (libg++) maintainer. Dreaming up, designing and
- implementing much of GCJ.
-
- * Devon Bowen helped port GCC to the Tahoe.
-
- * Don Bowman for mips-vxworks contributions.
-
- * Dave Brolley for work on cpplib and Chill.
-
- * Robert Brown implemented the support for Encore 32000 systems.
-
- * Christian Bruel for improvements to local store elimination.
-
- * Herman A.J. ten Brugge for various fixes.
-
- * Joerg Brunsmann for Java compiler hacking and help with the GCJ
- FAQ.
-
- * Joe Buck for his direction via the steering committee.
-
- * Craig Burley for leadership of the Fortran effort.
-
- * Stephan Buys for contributing Doxygen notes for libstdc++.
-
- * Paolo Carlini for libstdc++ work: lots of efficiency improvements
- to the string class, hard detective work on the frustrating
- localization issues, and keeping up with the problem reports.
-
- * John Carr for his alias work, SPARC hacking, infrastructure
- improvements, previous contributions to the steering committee,
- loop optimizations, etc.
-
- * Steve Chamberlain for support for the Hitachi SH and H8 processors
- and the PicoJava processor, and for GCJ config fixes.
-
- * Glenn Chambers for help with the GCJ FAQ.
-
- * John-Marc Chandonia for various libgcj patches.
-
- * Scott Christley for his Objective-C contributions.
-
- * Eric Christopher for his Java porting help and clean-ups.
-
- * Branko Cibej for more warning contributions.
-
- * The GNU Classpath project for all of their merged runtime code.
-
- * Nick Clifton for arm, mcore, fr30, v850, m32r work, `--help', and
- other random hacking.
-
- * Michael Cook for libstdc++ cleanup patches to reduce warnings.
-
- * Ralf Corsepius for SH testing and minor bugfixing.
-
- * Stan Cox for care and feeding of the x86 port and lots of behind
- the scenes hacking.
-
- * Alex Crain provided changes for the 3b1.
-
- * Ian Dall for major improvements to the NS32k port.
-
- * Dario Dariol contributed the four varieties of sample programs
- that print a copy of their source.
-
- * Russell Davidson for fstream and stringstream fixes in libstdc++.
-
- * Mo DeJong for GCJ and libgcj bug fixes.
-
- * Gabriel Dos Reis for contributions to g++, contributions and
- maintenance of GCC diagnostics infrastructure, libstdc++-v3,
- including valarray<>, complex<>, maintaining the numerics library
- (including that pesky <limits> :-) and keeping up-to-date anything
- to do with numbers.
-
- * Ulrich Drepper for his work on glibc, testing of GCC using glibc,
- ISO C99 support, CFG dumping support, etc., plus support of the
- C++ runtime libraries including for all kinds of C interface
- issues, contributing and maintaining complex<>, sanity checking
- and disbursement, configuration architecture, libio maintenance,
- and early math work.
-
- * Richard Earnshaw for his ongoing work with the ARM.
-
- * David Edelsohn for his direction via the steering committee,
- ongoing work with the RS6000/PowerPC port, help cleaning up Haifa
- loop changes, and for doing the entire AIX port of libstdc++ with
- his bare hands.
-
- * Kevin Ediger for the floating point formatting of num_put::do_put
- in libstdc++.
-
- * Phil Edwards for libstdc++ work including configuration hackery,
- documentation maintainer, chief breaker of the web pages, the
- occasional iostream bugfix, and work on shared library symbol
- versioning.
-
- * Paul Eggert for random hacking all over GCC.
-
- * Mark Elbrecht for various DJGPP improvements, and for libstdc++
- configuration support for locales and fstream-related fixes.
-
- * Vadim Egorov for libstdc++ fixes in strings, streambufs, and
- iostreams.
-
- * Ben Elliston for his work to move the Objective-C runtime into its
- own subdirectory and for his work on autoconf.
-
- * Marc Espie for OpenBSD support.
-
- * Doug Evans for much of the global optimization framework, arc,
- m32r, and SPARC work.
-
- * Fred Fish for BeOS support and Ada fixes.
-
- * Ivan Fontes Garcia for the Portugese translation of the GCJ FAQ.
-
- * Peter Gerwinski for various bugfixes and the Pascal front end.
-
- * Kaveh Ghazi for his direction via the steering committee and
- amazing work to make `-W -Wall' useful.
-
- * John Gilmore for a donation to the FSF earmarked improving GNU
- Java.
-
- * Judy Goldberg for c++ contributions.
-
- * Torbjorn Granlund for various fixes and the c-torture testsuite,
- multiply- and divide-by-constant optimization, improved long long
- support, improved leaf function register allocation, and his
- direction via the steering committee.
-
- * Anthony Green for his `-Os' contributions and Java front end work.
-
- * Stu Grossman for gdb hacking, allowing GCJ developers to debug our
- code.
-
- * Michael K. Gschwind contributed the port to the PDP-11.
-
- * Ron Guilmette implemented the `protoize' and `unprotoize' tools,
- the support for Dwarf symbolic debugging information, and much of
- the support for System V Release 4. He has also worked heavily on
- the Intel 386 and 860 support.
-
- * Bruno Haible for improvements in the runtime overhead for EH, new
- warnings and assorted bugfixes.
-
- * Andrew Haley for his amazing Java compiler and library efforts.
-
- * Chris Hanson assisted in making GCC work on HP-UX for the 9000
- series 300.
-
- * Michael Hayes for various thankless work he's done trying to get
- the c30/c40 ports functional. Lots of loop and unroll
- improvements and fixes.
-
- * Kate Hedstrom for staking the g77 folks with an initial testsuite.
-
- * Richard Henderson for his ongoing SPARC, alpha, and ia32 work, loop
- opts, and generally fixing lots of old problems we've ignored for
- years, flow rewrite and lots of further stuff, including reviewing
- tons of patches.
-
- * Nobuyuki Hikichi of Software Research Associates, Tokyo,
- contributed the support for the Sony NEWS machine.
-
- * Manfred Hollstein for his ongoing work to keep the m88k alive, lots
- of testing an bugfixing, particularly of our configury code.
-
- * Steve Holmgren for MachTen patches.
-
- * Jan Hubicka for his x86 port improvements.
-
- * Christian Iseli for various bugfixes.
-
- * Kamil Iskra for general m68k hacking.
-
- * Lee Iverson for random fixes and MIPS testing.
-
- * Andreas Jaeger for various fixes to the MIPS port
-
- * Jakub Jelinek for his SPARC work and sibling call optimizations as
- well as lots of bug fixes and test cases, and for improving the
- Java build system.
-
- * Janis Johnson for ia64 testing and fixes and for her quality
- improvement sidetracks.
-
- * J. Kean Johnston for OpenServer support.
-
- * Tim Josling for the sample language treelang based originally on
- Richard Kenner's ""toy" language".
-
- * Nicolai Josuttis for additional libstdc++ documentation.
-
- * Klaus Kaempf for his ongoing work to make alpha-vms a viable
- target.
-
- * David Kashtan of SRI adapted GCC to VMS.
-
- * Ryszard Kabatek for many, many libstdc++ bugfixes and
- optimizations of strings, especially member functions, and for
- auto_ptr fixes.
-
- * Geoffrey Keating for his ongoing work to make the PPC work for
- GNU/Linux and his automatic regression tester.
-
- * Brendan Kehoe for his ongoing work with g++ and for a lot of early
- work in just about every part of libstdc++.
-
- * Oliver M. Kellogg of Deutsche Aerospace contributed the port to the
- MIL-STD-1750A.
-
- * Richard Kenner of the New York University Ultracomputer Research
- Laboratory wrote the machine descriptions for the AMD 29000, the
- DEC Alpha, the IBM RT PC, and the IBM RS/6000 as well as the
- support for instruction attributes. He also made changes to
- better support RISC processors including changes to common
- subexpression elimination, strength reduction, function calling
- sequence handling, and condition code support, in addition to
- generalizing the code for frame pointer elimination and delay slot
- scheduling. Richard Kenner was also the head maintainer of GCC
- for several years.
-
- * Mumit Khan for various contributions to the Cygwin and Mingw32
- ports and maintaining binary releases for Windows hosts, and for
- massive libstdc++ porting work to Cygwin/Mingw32.
-
- * Robin Kirkham for cpu32 support.
-
- * Mark Klein for PA improvements.
-
- * Thomas Koenig for various bugfixes.
-
- * Bruce Korb for the new and improved fixincludes code.
-
- * Benjamin Kosnik for his g++ work and for leading the libstdc++-v3
- effort.
-
- * Charles LaBrec contributed the support for the Integrated Solutions
- 68020 system.
-
- * Jeff Law for his direction via the steering committee,
- coordinating the entire egcs project and GCC 2.95, rolling out
- snapshots and releases, handling merges from GCC2, reviewing tons
- of patches that might have fallen through the cracks else, and
- random but extensive hacking.
-
- * Marc Lehmann for his direction via the steering committee and
- helping with analysis and improvements of x86 performance.
-
- * Ted Lemon wrote parts of the RTL reader and printer.
-
- * Kriang Lerdsuwanakij for improvements to demangler and various c++
- fixes.
-
- * Warren Levy for tremendous work on libgcj (Java Runtime Library)
- and random work on the Java front end.
-
- * Alain Lichnewsky ported GCC to the MIPS CPU.
-
- * Oskar Liljeblad for hacking on AWT and his many Java bug reports
- and patches.
-
- * Robert Lipe for OpenServer support, new testsuites, testing, etc.
-
- * Weiwen Liu for testing and various bugfixes.
-
- * Dave Love for his ongoing work with the Fortran front end and
- runtime libraries.
-
- * Martin von Lo"wis for internal consistency checking infrastructure,
- various C++ improvements including namespace support, and tons of
- assistance with libstdc++/compiler merges.
-
- * H.J. Lu for his previous contributions to the steering committee,
- many x86 bug reports, prototype patches, and keeping the GNU/Linux
- ports working.
-
- * Greg McGary for random fixes and (someday) bounded pointers.
-
- * Andrew MacLeod for his ongoing work in building a real EH system,
- various code generation improvements, work on the global
- optimizer, etc.
-
- * Vladimir Makarov for hacking some ugly i960 problems, PowerPC
- hacking improvements to compile-time performance, overall
- knowledge and direction in the area of instruction scheduling, and
- design and implementation of the automaton based instruction
- scheduler.
-
- * Bob Manson for his behind the scenes work on dejagnu.
-
- * Philip Martin for lots of libstdc++ string and vector iterator
- fixes and improvements, and string clean up and testsuites.
-
- * All of the Mauve project contributors, for Java test code.
-
- * Bryce McKinlay for numerous GCJ and libgcj fixes and improvements.
-
- * Adam Megacz for his work on the Win32 port of GCJ.
-
- * Michael Meissner for LRS framework, ia32, m32r, v850, m88k, MIPS,
- powerpc, haifa, ECOFF debug support, and other assorted hacking.
-
- * Jason Merrill for his direction via the steering committee and
- leading the g++ effort.
-
- * David Miller for his direction via the steering committee, lots of
- SPARC work, improvements in jump.c and interfacing with the Linux
- kernel developers.
-
- * Gary Miller ported GCC to Charles River Data Systems machines.
-
- * Alfred Minarik for libstdc++ string and ios bugfixes, and turning
- the entire libstdc++ testsuite namespace-compatible.
-
- * Mark Mitchell for his direction via the steering committee,
- mountains of C++ work, load/store hoisting out of loops, alias
- analysis improvements, ISO C `restrict' support, and serving as
- release manager for GCC 3.x.
-
- * Alan Modra for various GNU/Linux bits and testing.
-
- * Toon Moene for his direction via the steering committee, Fortran
- maintenance, and his ongoing work to make us make Fortran run fast.
-
- * Jason Molenda for major help in the care and feeding of all the
- services on the gcc.gnu.org (formerly egcs.cygnus.com)
- machine--mail, web services, ftp services, etc etc. Doing all
- this work on scrap paper and the backs of envelopes would have
- been... difficult.
-
- * Catherine Moore for fixing various ugly problems we have sent her
- way, including the haifa bug which was killing the Alpha & PowerPC
- Linux kernels.
-
- * Mike Moreton for his various Java patches.
-
- * David Mosberger-Tang for various Alpha improvements.
-
- * Stephen Moshier contributed the floating point emulator that
- assists in cross-compilation and permits support for floating
- point numbers wider than 64 bits and for ISO C99 support.
-
- * Bill Moyer for his behind the scenes work on various issues.
-
- * Philippe De Muyter for his work on the m68k port.
-
- * Joseph S. Myers for his work on the PDP-11 port, format checking
- and ISO C99 support, and continuous emphasis on (and contributions
- to) documentation.
-
- * Nathan Myers for his work on libstdc++-v3: architecture and
- authorship through the first three snapshots, including
- implementation of locale infrastructure, string, shadow C headers,
- and the initial project documentation (DESIGN, CHECKLIST, and so
- forth). Later, more work on MT-safe string and shadow headers.
-
- * Felix Natter for documentation on porting libstdc++.
-
- * NeXT, Inc. donated the front end that supports the Objective-C
- language.
-
- * Hans-Peter Nilsson for the CRIS and MMIX ports, improvements to
- the search engine setup, various documentation fixes and other
- small fixes.
-
- * Geoff Noer for this work on getting cygwin native builds working.
-
- * David O'Brien for the FreeBSD/alpha, FreeBSD/AMD x86-64,
- FreeBSD/ARM, FreeBSD/PowerPC, and FreeBSD/SPARC64 ports and
- related infrastructure improvements.
-
- * Alexandre Oliva for various build infrastructure improvements,
- scripts and amazing testing work, including keeping libtool issues
- sane and happy.
-
- * Melissa O'Neill for various NeXT fixes.
-
- * Rainer Orth for random MIPS work, including improvements to our o32
- ABI support, improvements to dejagnu's MIPS support, Java
- configuration clean-ups and porting work, etc.
-
- * Paul Petersen wrote the machine description for the Alliant FX/8.
-
- * Alexandre Petit-Bianco for implementing much of the Java compiler
- and continued Java maintainership.
-
- * Matthias Pfaller for major improvements to the NS32k port.
-
- * Gerald Pfeifer for his direction via the steering committee,
- pointing out lots of problems we need to solve, maintenance of the
- web pages, and taking care of documentation maintenance in general.
-
- * Ovidiu Predescu for his work on the Objective-C front end and
- runtime libraries.
-
- * Ken Raeburn for various improvements to checker, MIPS ports and
- various cleanups in the compiler.
-
- * Rolf W. Rasmussen for hacking on AWT.
-
- * David Reese of Sun Microsystems contributed to the Solaris on
- PowerPC port.
-
- * Joern Rennecke for maintaining the sh port, loop, regmove & reload
- hacking.
-
- * Loren J. Rittle for improvements to libstdc++-v3 including the
- FreeBSD port, threading fixes, thread-related configury changes,
- critical threading documentation, and solutions to really tricky
- I/O problems.
-
- * Craig Rodrigues for processing tons of bug reports.
-
- * Gavin Romig-Koch for lots of behind the scenes MIPS work.
-
- * Ken Rose for fixes to our delay slot filling code.
-
- * Paul Rubin wrote most of the preprocessor.
-
- * Chip Salzenberg for libstdc++ patches and improvements to locales,
- traits, Makefiles, libio, libtool hackery, and "long long" support.
-
- * Juha Sarlin for improvements to the H8 code generator.
-
- * Greg Satz assisted in making GCC work on HP-UX for the 9000 series
- 300.
-
- * Bradley Schatz for his work on the GCJ FAQ.
-
- * Peter Schauer wrote the code to allow debugging to work on the
- Alpha.
-
- * William Schelter did most of the work on the Intel 80386 support.
-
- * Bernd Schmidt for various code generation improvements and major
- work in the reload pass as well a serving as release manager for
- GCC 2.95.3.
-
- * Peter Schmid for constant testing of libstdc++ - especially
- application testing, going above and beyond what was requested for
- the release criteria - and libstdc++ header file tweaks.
-
- * Jason Schroeder for jcf-dump patches.
-
- * Andreas Schwab for his work on the m68k port.
-
- * Joel Sherrill for his direction via the steering committee, RTEMS
- contributions and RTEMS testing.
-
- * Nathan Sidwell for many C++ fixes/improvements.
-
- * Jeffrey Siegal for helping RMS with the original design of GCC,
- some code which handles the parse tree and RTL data structures,
- constant folding and help with the original VAX & m68k ports.
-
- * Kenny Simpson for prompting libstdc++ fixes due to defect reports
- from the LWG (thereby keeping us in line with updates from the
- ISO).
-
- * Franz Sirl for his ongoing work with making the PPC port stable
- for linux.
-
- * Andrey Slepuhin for assorted AIX hacking.
-
- * Christopher Smith did the port for Convex machines.
-
- * Randy Smith finished the Sun FPA support.
-
- * Scott Snyder for queue, iterator, istream, and string fixes and
- libstdc++ testsuite entries.
-
- * Brad Spencer for contributions to the GLIBCPP_FORCE_NEW technique.
-
- * Richard Stallman, for writing the original gcc and launching the
- GNU project.
-
- * Jan Stein of the Chalmers Computer Society provided support for
- Genix, as well as part of the 32000 machine description.
-
- * Nigel Stephens for various mips16 related fixes/improvements.
-
- * Jonathan Stone wrote the machine description for the Pyramid
- computer.
-
- * Graham Stott for various infrastructure improvements.
-
- * John Stracke for his Java HTTP protocol fixes.
-
- * Mike Stump for his Elxsi port, g++ contributions over the years
- and more recently his vxworks contributions
-
- * Jeff Sturm for Java porting help, bug fixes, and encouragement.
-
- * Shigeya Suzuki for this fixes for the bsdi platforms.
-
- * Ian Lance Taylor for his mips16 work, general configury hacking,
- fixincludes, etc.
-
- * Holger Teutsch provided the support for the Clipper CPU.
-
- * Gary Thomas for his ongoing work to make the PPC work for
- GNU/Linux.
-
- * Philipp Thomas for random bugfixes throughout the compiler
-
- * Jason Thorpe for thread support in libstdc++ on NetBSD.
-
- * Kresten Krab Thorup wrote the run time support for the Objective-C
- language and the fantastic Java bytecode interpreter.
-
- * Michael Tiemann for random bugfixes, the first instruction
- scheduler, initial C++ support, function integration, NS32k, SPARC
- and M88k machine description work, delay slot scheduling.
-
- * Andreas Tobler for his work porting libgcj to Darwin.
-
- * Teemu Torma for thread safe exception handling support.
-
- * Leonard Tower wrote parts of the parser, RTL generator, and RTL
- definitions, and of the VAX machine description.
-
- * Tom Tromey for internationalization support and for his many Java
- contributions and libgcj maintainership.
-
- * Lassi Tuura for improvements to config.guess to determine HP
- processor types.
-
- * Petter Urkedal for libstdc++ CXXFLAGS, math, and algorithms fixes.
-
- * Brent Verner for work with the libstdc++ cshadow files and their
- associated configure steps.
-
- * Todd Vierling for contributions for NetBSD ports.
-
- * Jonathan Wakely for contributing libstdc++ Doxygen notes and XHTML
- guidance.
-
- * Dean Wakerley for converting the install documentation from HTML
- to texinfo in time for GCC 3.0.
-
- * Krister Walfridsson for random bugfixes.
-
- * Stephen M. Webb for time and effort on making libstdc++ shadow
- files work with the tricky Solaris 8+ headers, and for pushing the
- build-time header tree.
-
- * John Wehle for various improvements for the x86 code generator,
- related infrastructure improvements to help x86 code generation,
- value range propagation and other work, WE32k port.
-
- * Zack Weinberg for major work on cpplib and various other bugfixes.
-
- * Matt Welsh for help with Linux Threads support in GCJ.
-
- * Urban Widmark for help fixing java.io.
-
- * Mark Wielaard for new Java library code and his work integrating
- with Classpath.
-
- * Dale Wiles helped port GCC to the Tahoe.
-
- * Bob Wilson from Tensilica, Inc. for the Xtensa port.
-
- * Jim Wilson for his direction via the steering committee, tackling
- hard problems in various places that nobody else wanted to work
- on, strength reduction and other loop optimizations.
-
- * Carlo Wood for various fixes.
-
- * Tom Wood for work on the m88k port.
-
- * Masanobu Yuhara of Fujitsu Laboratories implemented the machine
- description for the Tron architecture (specifically, the Gmicro).
-
- * Kevin Zachmann helped ported GCC to the Tahoe.
-
- * Gilles Zunino for help porting Java to Irix.
-
-
- We'd also like to thank the folks who have contributed time and
-energy in testing GCC:
-
- * Michael Abd-El-Malek
-
- * Thomas Arend
-
- * Bonzo Armstrong
-
- * Steven Ashe
-
- * Chris Baldwin
-
- * David Billinghurst
-
- * Jim Blandy
-
- * Stephane Bortzmeyer
-
- * Horst von Brand
-
- * Frank Braun
-
- * Rodney Brown
-
- * Joe Buck
-
- * Craig Burley
-
- * Sidney Cadot
-
- * Bradford Castalia
-
- * Ralph Doncaster
-
- * Ulrich Drepper
-
- * David Edelsohn
-
- * Richard Emberson
-
- * Levente Farkas
-
- * Graham Fawcett
-
- * Robert A. French
-
- * Jo"rgen Freyh
-
- * Mark K. Gardner
-
- * Charles-Antoine Gauthier
-
- * Yung Shing Gene
-
- * Kaveh Ghazi
-
- * David Gilbert
-
- * Simon Gornall
-
- * Fred Gray
-
- * John Griffin
-
- * Patrik Hagglund
-
- * Phil Hargett
-
- * Amancio Hasty
-
- * Bryan W. Headley
-
- * Kate Hedstrom
-
- * Richard Henderson
-
- * Kevin B. Hendricks
-
- * Manfred Hollstein
-
- * Kamil Iskra
-
- * Joep Jansen
-
- * Christian Joensson
-
- * David Kidd
-
- * Tobias Kuipers
-
- * Anand Krishnaswamy
-
- * Jeff Law
-
- * Robert Lipe
-
- * llewelly
-
- * Damon Love
-
- * Dave Love
-
- * H.J. Lu
-
- * Brad Lucier
-
- * Mumit Khan
-
- * Matthias Klose
-
- * Martin Knoblauch
-
- * Jesse Macnish
-
- * David Miller
-
- * Toon Moene
-
- * Stefan Morrell
-
- * Anon A. Mous
-
- * Matthias Mueller
-
- * Pekka Nikander
-
- * Alexandre Oliva
-
- * Jon Olson
-
- * Magnus Persson
-
- * Chris Pollard
-
- * Richard Polton
-
- * David Rees
-
- * Paul Reilly
-
- * Tom Reilly
-
- * Loren J. Rittle
-
- * Torsten Rueger
-
- * Danny Sadinoff
-
- * Marc Schifer
-
- * Peter Schmid
-
- * David Schuler
-
- * Vin Shelton
-
- * Franz Sirl
-
- * Tim Souder
-
- * Mike Stump
-
- * Adam Sulmicki
-
- * George Talbot
-
- * Gregory Warnes
-
- * Carlo Wood
-
- * David E. Young
-
- * And many others
-
- And finally we'd like to thank everyone who uses the compiler,
-submits bug reports and generally reminds us why we're doing this work
-in the first place.
-
-\1f
-File: gccint.info, Node: Option Index, Next: Index, Prev: Contributors, Up: Top
-
-Option Index
-************
-
- GCC's command line options are indexed here without any initial `-'
-or `--'. Where an option has both positive and negative forms (such as
-`-fOPTION' and `-fno-OPTION'), relevant entries in the manual are
-indexed under the most appropriate form; it may sometimes be useful to
-look up both forms.
-
-* Menu:
-
-* dB: Passes.
-* dc: Passes.
-* dd: Passes.
-* dE: Passes.
-* de: Passes.
-* df: Passes.
-* dg: Passes.
-* dG: Passes.
-* di: Passes.
-* dj: Passes.
-* dk: Passes.
-* dl: Passes.
-* dL: Passes.
-* dN: Passes.
-* dR: Passes.
-* dr: Passes.
-* dS: Passes.
-* ds: Passes.
-* dt: Passes.
-* dW: Passes.
-* dX: Passes.
-* frerun-cse-after-loop: Passes.
-* fssa: Passes.
-* fssa-ccp: Passes.
-* fssa-dce: Passes.
-* fthread-jumps: Passes.
-* msoft-float: Interface.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Index, Prev: Option Index, Up: Top
-
-Index
-*****
-
-* Menu:
-
-* ! in constraint: Multi-Alternative.
-* # in constraint: Modifiers.
-* # in template: Output Template.
-* #pragma: Misc.
-* % in constraint: Modifiers.
-* % in template: Output Template.
-* & in constraint: Modifiers.
-* (nil): RTL Objects.
-* * in constraint: Modifiers.
-* * in template: Output Statement.
-* + in constraint: Modifiers.
-* /c in RTL dump: Flags.
-* /f in RTL dump: Flags.
-* /i in RTL dump: Flags.
-* /j in RTL dump: Flags.
-* /s in RTL dump: Flags.
-* /u in RTL dump: Flags.
-* /v in RTL dump: Flags.
-* 0 in constraint: Simple Constraints.
-* < in constraint: Simple Constraints.
-* = in constraint: Modifiers.
-* > in constraint: Simple Constraints.
-* ? in constraint: Multi-Alternative.
-* \: Output Template.
-* __builtin_args_info: Varargs.
-* __builtin_classify_type: Varargs.
-* __builtin_next_arg: Varargs.
-* __builtin_saveregs: Varargs.
-* __CTOR_LIST__: Initialization.
-* __DTOR_LIST__: Initialization.
-* __main: Collect2.
-* abort: Portability.
-* abs: Arithmetic.
-* abs and attributes: Expressions.
-* absM2 instruction pattern: Standard Names.
-* absolute value: Arithmetic.
-* access to operands: Accessors.
-* accessors: Accessors.
-* ACCUMULATE_OUTGOING_ARGS: Stack Arguments.
-* ACCUMULATE_OUTGOING_ARGS and stack frames: Function Entry.
-* ADA_LONG_TYPE_SIZE: Type Layout.
-* ADDITIONAL_REGISTER_NAMES: Instruction Output.
-* addM3 instruction pattern: Standard Names.
-* addr_diff_vec: Side Effects.
-* addr_diff_vec, length of: Insn Lengths.
-* ADDR_EXPR: Expression trees.
-* addr_vec: Side Effects.
-* addr_vec, length of: Insn Lengths.
-* address constraints: Simple Constraints.
-* ADDRESS_COST: Costs.
-* address_operand: Simple Constraints.
-* addressing modes: Addressing Modes.
-* addressof: Regs and Memory.
-* ADJUST_FIELD_ALIGN: Storage Layout.
-* ADJUST_INSN_LENGTH: Insn Lengths.
-* aggregates as return values: Aggregate Return.
-* ALL_REGS: Register Classes.
-* ALLOCATE_INITIAL_VALUE: Misc.
-* allocate_stack instruction pattern: Standard Names.
-* ALLOCATE_TRAMPOLINE: Trampolines.
-* analysis, data flow: Passes.
-* and: Arithmetic.
-* and and attributes: Expressions.
-* and, canonicalization of: Insn Canonicalizations.
-* andM3 instruction pattern: Standard Names.
-* APPLY_RESULT_SIZE: Scalar Return.
-* ARG_POINTER_CFA_OFFSET: Frame Layout.
-* ARG_POINTER_REGNUM: Frame Registers.
-* ARG_POINTER_REGNUM and virtual registers: Regs and Memory.
-* arg_pointer_rtx: Frame Registers.
-* ARGS_GROW_DOWNWARD: Frame Layout.
-* argument passing: Interface.
-* arguments in registers: Register Arguments.
-* arguments on stack: Stack Arguments.
-* arithmetic libraries: Interface.
-* arithmetic shift: Arithmetic.
-* arithmetic simplifications: Passes.
-* arithmetic, in RTL: Arithmetic.
-* ARITHMETIC_TYPE_P: Types.
-* array: Types.
-* ARRAY_REF: Expression trees.
-* ARRAY_TYPE: Types.
-* ashift: Arithmetic.
-* ashift and attributes: Expressions.
-* ashiftrt: Arithmetic.
-* ashiftrt and attributes: Expressions.
-* ashlM3 instruction pattern: Standard Names.
-* ashrM3 instruction pattern: Standard Names.
-* ASM_APP_OFF: File Framework.
-* ASM_APP_ON: File Framework.
-* ASM_CLOBBERS: Function Bodies.
-* ASM_COMMENT_START: File Framework.
-* ASM_CV_QUAL: Function Bodies.
-* ASM_DECLARE_CLASS_REFERENCE: Label Output.
-* ASM_DECLARE_FUNCTION_NAME: Label Output.
-* ASM_DECLARE_FUNCTION_SIZE: Label Output.
-* ASM_DECLARE_OBJECT_NAME: Label Output.
-* ASM_DECLARE_REGISTER_GLOBAL: Label Output.
-* ASM_DECLARE_UNRESOLVED_REFERENCE: Label Output.
-* ASM_FILE_END: File Framework.
-* ASM_FILE_START: File Framework.
-* ASM_FINAL_SPEC: Driver.
-* ASM_FINISH_DECLARE_OBJECT: Label Output.
-* ASM_FORMAT_PRIVATE_NAME: Label Output.
-* asm_fprintf: Instruction Output.
-* ASM_FPRINTF_EXTENSIONS: Instruction Output.
-* ASM_GENERATE_INTERNAL_LABEL: Label Output.
-* ASM_GLOBALIZE_LABEL: Label Output.
-* asm_input: Side Effects.
-* ASM_INPUTS: Function Bodies.
-* ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX: Exception Handling.
-* ASM_NO_SKIP_IN_TEXT: Alignment Output.
-* asm_noperands: Insns.
-* asm_operands, RTL sharing: Sharing.
-* asm_operands, usage: Assembler.
-* ASM_OUTPUT_ADDR_DIFF_ELT: Dispatch Tables.
-* ASM_OUTPUT_ADDR_VEC_ELT: Dispatch Tables.
-* ASM_OUTPUT_ALIGN: Alignment Output.
-* ASM_OUTPUT_ALIGNED_BSS: Uninitialized Data.
-* ASM_OUTPUT_ALIGNED_COMMON: Uninitialized Data.
-* ASM_OUTPUT_ALIGNED_DECL_COMMON: Uninitialized Data.
-* ASM_OUTPUT_ALIGNED_DECL_LOCAL: Uninitialized Data.
-* ASM_OUTPUT_ALIGNED_LOCAL: Uninitialized Data.
-* ASM_OUTPUT_ALTERNATE_LABEL_NAME: Label Output.
-* ASM_OUTPUT_ASCII: Data Output.
-* ASM_OUTPUT_BSS: Uninitialized Data.
-* ASM_OUTPUT_CASE_END: Dispatch Tables.
-* ASM_OUTPUT_CASE_LABEL: Dispatch Tables.
-* ASM_OUTPUT_COMMON: Uninitialized Data.
-* ASM_OUTPUT_DEBUG_LABEL: Label Output.
-* ASM_OUTPUT_DEF: Label Output.
-* ASM_OUTPUT_DEF_FROM_DECLS: Label Output.
-* ASM_OUTPUT_DEFINE_LABEL_DIFFERENCE_SYMBOL: Label Output.
-* ASM_OUTPUT_EXTERNAL: Label Output.
-* ASM_OUTPUT_EXTERNAL_LIBCALL: Label Output.
-* ASM_OUTPUT_FDESC: Data Output.
-* ASM_OUTPUT_IDENT: File Framework.
-* ASM_OUTPUT_INTERNAL_LABEL: Label Output.
-* ASM_OUTPUT_LABEL: Label Output.
-* ASM_OUTPUT_LABEL_REF: Label Output.
-* ASM_OUTPUT_LABELREF: Label Output.
-* ASM_OUTPUT_LOCAL: Uninitialized Data.
-* ASM_OUTPUT_MAX_SKIP_ALIGN: Alignment Output.
-* ASM_OUTPUT_MI_THUNK: Function Entry.
-* ASM_OUTPUT_OPCODE: Instruction Output.
-* ASM_OUTPUT_POOL_EPILOGUE: Data Output.
-* ASM_OUTPUT_POOL_PROLOGUE: Data Output.
-* ASM_OUTPUT_REG_POP: Instruction Output.
-* ASM_OUTPUT_REG_PUSH: Instruction Output.
-* ASM_OUTPUT_SHARED_BSS: Uninitialized Data.
-* ASM_OUTPUT_SHARED_COMMON: Uninitialized Data.
-* ASM_OUTPUT_SHARED_LOCAL: Uninitialized Data.
-* ASM_OUTPUT_SKIP: Alignment Output.
-* ASM_OUTPUT_SOURCE_FILENAME: File Framework.
-* ASM_OUTPUT_SOURCE_LINE: File Framework.
-* ASM_OUTPUT_SPECIAL_POOL_ENTRY: Data Output.
-* ASM_OUTPUT_SYMBOL_REF: Label Output.
-* ASM_OUTPUT_WEAK_ALIAS: Label Output.
-* ASM_OUTPUTS: Function Bodies.
-* ASM_PREFERRED_EH_DATA_FORMAT: Exception Handling.
-* ASM_SPEC: Driver.
-* ASM_STABD_OP: DBX Options.
-* ASM_STABN_OP: DBX Options.
-* ASM_STABS_OP: DBX Options.
-* ASM_STMT: Function Bodies.
-* ASM_STRING: Function Bodies.
-* ASM_WEAKEN_DECL: Label Output.
-* ASM_WEAKEN_LABEL: Label Output.
-* assemble_name: Label Output.
-* assembler format: File Framework.
-* assembler instructions in RTL: Assembler.
-* ASSEMBLER_DIALECT: Instruction Output.
-* assigning attribute values to insns: Tagging Insns.
-* assignment operator: Function Basics.
-* asterisk in template: Output Statement.
-* atof: Cross-compilation.
-* attr <1>: Tagging Insns.
-* attr: Expressions.
-* attr_flag: Expressions.
-* attribute expressions: Expressions.
-* attribute specifications: Attr Example.
-* attribute specifications example: Attr Example.
-* attributes: Attributes.
-* attributes, defining: Defining Attributes.
-* attributes, target-specific: Target Attributes.
-* autoincrement addressing, availability: Portability.
-* autoincrement/decrement addressing: Simple Constraints.
-* autoincrement/decrement analysis: Passes.
-* AVOID_CCMODE_COPIES: Values in Registers.
-* backslash: Output Template.
-* barrier: Insns.
-* BASE_REG_CLASS: Register Classes.
-* basic block reordering: Passes.
-* basic blocks: Passes.
-* bCOND instruction pattern: Standard Names.
-* bcopy, implicit usage: Library Calls.
-* BIGGEST_ALIGNMENT: Storage Layout.
-* BIGGEST_FIELD_ALIGNMENT: Storage Layout.
-* BImode: Machine Modes.
-* BIND_EXPR: Expression trees.
-* BINFO_TYPE: Classes.
-* bit-fields: Bit-Fields.
-* BIT_AND_EXPR: Expression trees.
-* BIT_IOR_EXPR: Expression trees.
-* BIT_NOT_EXPR: Expression trees.
-* BIT_XOR_EXPR: Expression trees.
-* BITFIELD_NBYTES_LIMITED: Storage Layout.
-* BITS_BIG_ENDIAN: Storage Layout.
-* BITS_BIG_ENDIAN, effect on sign_extract: Bit-Fields.
-* BITS_PER_UNIT: Storage Layout.
-* BITS_PER_WORD: Storage Layout.
-* bitwise complement: Arithmetic.
-* bitwise exclusive-or: Arithmetic.
-* bitwise inclusive-or: Arithmetic.
-* bitwise logical-and: Arithmetic.
-* BLKmode: Machine Modes.
-* BLKmode, and function return values: Calls.
-* BOOL_TYPE_SIZE: Type Layout.
-* BOOLEAN_TYPE: Types.
-* branch shortening: Passes.
-* BRANCH_COST: Costs.
-* break_out_memory_refs: Addressing Modes.
-* BREAK_STMT: Function Bodies.
-* BSS_SECTION_ASM_OP: Sections.
-* builtin_longjmp instruction pattern: Standard Names.
-* BUILTIN_SETJMP_FRAME_VALUE: Frame Layout.
-* builtin_setjmp_receiver instruction pattern: Standard Names.
-* builtin_setjmp_setup instruction pattern: Standard Names.
-* byte_mode: Machine Modes.
-* BYTES_BIG_ENDIAN: Storage Layout.
-* BYTES_BIG_ENDIAN, effect on subreg: Regs and Memory.
-* bzero, implicit usage: Library Calls.
-* C statements for assembler output: Output Statement.
-* C/C++ Internal Representation: Trees.
-* C4X_FLOAT_FORMAT: Storage Layout.
-* call <1>: Side Effects.
-* call: Flags.
-* call instruction pattern: Standard Names.
-* call usage: Calls.
-* call, in insn_list: Flags.
-* call-clobbered register: Register Basics.
-* call-saved register: Register Basics.
-* call-used register: Register Basics.
-* CALL_EXPR: Expression trees.
-* call_insn: Insns.
-* call_insn and /j: Flags.
-* call_insn and /u: Flags.
-* CALL_INSN_FUNCTION_USAGE: Insns.
-* call_pop instruction pattern: Standard Names.
-* CALL_POPS_ARGS: Stack Arguments.
-* CALL_REALLY_USED_REGISTERS: Register Basics.
-* CALL_USED_REGISTERS: Register Basics.
-* call_used_regs: Register Basics.
-* call_value instruction pattern: Standard Names.
-* call_value_pop instruction pattern: Standard Names.
-* CALLER_SAVE_PROFITABLE: Caller Saves.
-* calling conventions: Stack and Calling.
-* calling functions in RTL: Calls.
-* CAN_DEBUG_WITHOUT_FP: Run-time Target.
-* CAN_ELIMINATE: Elimination.
-* canadian: Configure Terms.
-* canonicalization of instructions: Insn Canonicalizations.
-* CANONICALIZE_COMPARISON: Condition Code.
-* canonicalize_funcptr_for_compare instruction pattern: Standard Names.
-* CASE_DROPS_THROUGH: Misc.
-* CASE_VALUES_THRESHOLD: Misc.
-* CASE_VECTOR_MODE: Misc.
-* CASE_VECTOR_PC_RELATIVE: Misc.
-* CASE_VECTOR_SHORTEN_MODE: Misc.
-* casesi instruction pattern: Standard Names.
-* cc0: Regs and Memory.
-* cc0, RTL sharing: Sharing.
-* cc0_rtx: Regs and Memory.
-* CC1_SPEC: Driver.
-* CC1PLUS_SPEC: Driver.
-* cc_status: Condition Code.
-* CC_STATUS_MDEP: Condition Code.
-* CC_STATUS_MDEP_INIT: Condition Code.
-* CCmode: Machine Modes.
-* CDImode: Machine Modes.
-* change_address: Standard Names.
-* CHAR_TYPE_SIZE: Type Layout.
-* CHECK_FLOAT_VALUE: Storage Layout.
-* check_stack instruction pattern: Standard Names.
-* CHImode: Machine Modes.
-* class: Classes.
-* class definitions, register: Register Classes.
-* class preference constraints: Class Preferences.
-* CLASS_LIKELY_SPILLED_P: Register Classes.
-* CLASS_MAX_NREGS: Register Classes.
-* CLASS_TYPE_P: Types.
-* classes of RTX codes: RTL Classes.
-* CLASSTYPE_DECLARED_CLASS: Classes.
-* CLASSTYPE_HAS_MUTABLE: Classes.
-* CLASSTYPE_NON_POD_P: Classes.
-* CLEANUP_DECL: Function Bodies.
-* CLEANUP_EXPR: Function Bodies.
-* CLEANUP_POINT_EXPR: Expression trees.
-* CLEANUP_STMT: Function Bodies.
-* CLEAR_INSN_CACHE: Trampolines.
-* clobber: Side Effects.
-* clrstrM instruction pattern: Standard Names.
-* cmpM instruction pattern: Standard Names.
-* cmpstrM instruction pattern: Standard Names.
-* code generation RTL sequences: Expander Definitions.
-* code motion: Passes.
-* code_label: Insns.
-* code_label and /i: Flags.
-* CODE_LABEL_NUMBER: Insns.
-* codes, RTL expression: RTL Objects.
-* COImode: Machine Modes.
-* COLLECT2_HOST_INITIALIZATION: Host Config.
-* COLLECT_EXPORT_LIST: Misc.
-* combiner pass: Regs and Memory.
-* common subexpression elimination: Passes.
-* compare: Arithmetic.
-* compare, canonicalization of: Insn Canonicalizations.
-* compiler passes and files: Passes.
-* complement, bitwise: Arithmetic.
-* COMPLEX_CST: Expression trees.
-* COMPLEX_EXPR: Expression trees.
-* COMPLEX_TYPE: Types.
-* COMPONENT_REF: Expression trees.
-* COMPOUND_BODY: Function Bodies.
-* COMPOUND_EXPR: Expression trees.
-* COMPOUND_LITERAL_EXPR: Expression trees.
-* COMPOUND_LITERAL_EXPR_DECL: Expression trees.
-* COMPOUND_LITERAL_EXPR_DECL_STMT: Expression trees.
-* COMPOUND_STMT: Function Bodies.
-* computing the length of an insn: Insn Lengths.
-* cond: Comparisons.
-* cond and attributes: Expressions.
-* cond_exec: Side Effects.
-* COND_EXPR: Expression trees.
-* condition code register: Regs and Memory.
-* condition code status: Condition Code.
-* condition codes: Comparisons.
-* conditional constant propagation: Passes.
-* Conditional Constant Propagation, SSA based: Passes.
-* conditional execution: Conditional Execution.
-* CONDITIONAL_REGISTER_USAGE: Register Basics.
-* conditional_trap instruction pattern: Standard Names.
-* conditions, in patterns: Patterns.
-* configuration file: Host Config.
-* configure terms: Configure Terms.
-* CONJ_EXPR: Expression trees.
-* CONST0_RTX: Constants.
-* const0_rtx: Constants.
-* CONST1_RTX: Constants.
-* const1_rtx: Constants.
-* CONST2_RTX: Constants.
-* const2_rtx: Constants.
-* CONST_COSTS: Costs.
-* CONST_DECL: Declarations.
-* const_double: Constants.
-* const_double, RTL sharing: Sharing.
-* CONST_DOUBLE_CHAIN: Constants.
-* CONST_DOUBLE_LOW: Constants.
-* CONST_DOUBLE_MEM: Constants.
-* CONST_DOUBLE_OK_FOR_LETTER_P: Register Classes.
-* const_int: Constants.
-* const_int and attribute tests: Expressions.
-* const_int and attributes: Expressions.
-* const_int, RTL sharing: Sharing.
-* CONST_OK_FOR_LETTER_P: Register Classes.
-* CONST_OR_PURE_CALL_P: Flags.
-* const_string: Constants.
-* const_string and attributes: Expressions.
-* const_true_rtx: Constants.
-* const_vector: Constants.
-* const_vector, RTL sharing: Sharing.
-* constant attributes: Constant Attributes.
-* constant definitions: Constant Definitions.
-* constant folding: Passes.
-* constant folding and floating point: Cross-compilation.
-* constant propagation: Passes.
-* CONSTANT_ADDRESS_P: Addressing Modes.
-* CONSTANT_AFTER_FUNCTION_P: Data Output.
-* CONSTANT_ALIGNMENT: Storage Layout.
-* CONSTANT_P: Addressing Modes.
-* CONSTANT_POOL_ADDRESS_P: Flags.
-* CONSTANT_POOL_BEFORE_FUNCTION: Data Output.
-* constants in constraints: Simple Constraints.
-* constm1_rtx: Constants.
-* constraint modifier characters: Modifiers.
-* constraint, matching: Simple Constraints.
-* constraints: Constraints.
-* constraints, machine specific: Machine Constraints.
-* CONSTRUCTOR: Expression trees.
-* constructor: Function Basics.
-* constructors, automatic calls: Collect2.
-* constructors, output of: Initialization.
-* container: Containers.
-* CONTINUE_STMT: Function Bodies.
-* contributors: Contributors.
-* controlling register usage: Register Basics.
-* controlling the compilation driver: Driver.
-* conventions, run-time: Interface.
-* conversions: Conversions.
-* CONVERT_EXPR: Expression trees.
-* copy constructor: Function Basics.
-* copy propagation: Passes.
-* copy_rtx: Addressing Modes.
-* copy_rtx_if_shared: Sharing.
-* costs of instructions: Costs.
-* COSTS_N_INSNS: Costs.
-* CP_INTEGRAL_TYPE: Types.
-* cp_namespace_decls: Namespaces.
-* CP_TYPE_CONST_NON_VOLATILE_P: Types.
-* CP_TYPE_CONST_P: Types.
-* CP_TYPE_QUALS: Types.
-* CP_TYPE_RESTRICT_P: Types.
-* CP_TYPE_VOLATILE_P: Types.
-* CPLUSPLUS_CPP_SPEC: Driver.
-* CPP_PREDEFINES: Run-time Target.
-* cpp_register_pragma: Misc.
-* CPP_SPEC: Driver.
-* CQImode: Machine Modes.
-* cross compilation and floating point: Cross-compilation.
-* CRT_CALL_STATIC_FUNCTION: Sections.
-* CRTSTUFF_T_CFLAGS: Target Fragment.
-* CRTSTUFF_T_CFLAGS_S: Target Fragment.
-* CSImode: Machine Modes.
-* CTImode: Machine Modes.
-* CUMULATIVE_ARGS: Register Arguments.
-* current_function_epilogue_delay_list: Function Entry.
-* current_function_is_leaf: Leaf Functions.
-* current_function_outgoing_args_size: Stack Arguments.
-* current_function_pops_args: Function Entry.
-* current_function_pretend_args_size: Function Entry.
-* current_function_uses_only_leaf_regs: Leaf Functions.
-* current_insn_predicate: Conditional Execution.
-* cycle_display instruction pattern: Standard Names.
-* data flow analysis: Passes.
-* data structures: Per-Function Data.
-* DATA_ALIGNMENT: Storage Layout.
-* data_section: Sections.
-* DATA_SECTION_ASM_OP: Sections.
-* DBR_OUTPUT_SEQEND: Instruction Output.
-* dbr_sequence_length: Instruction Output.
-* DBX_BLOCKS_FUNCTION_RELATIVE: DBX Options.
-* DBX_CONTIN_CHAR: DBX Options.
-* DBX_CONTIN_LENGTH: DBX Options.
-* DBX_DEBUGGING_INFO: DBX Options.
-* DBX_FUNCTION_FIRST: DBX Options.
-* DBX_LBRAC_FIRST: DBX Options.
-* DBX_MEMPARM_STABS_LETTER: DBX Options.
-* DBX_NO_XREFS: DBX Options.
-* DBX_OUTPUT_ENUM: DBX Hooks.
-* DBX_OUTPUT_FUNCTION_END: DBX Hooks.
-* DBX_OUTPUT_LBRAC: DBX Hooks.
-* DBX_OUTPUT_MAIN_SOURCE_DIRECTORY: File Names and DBX.
-* DBX_OUTPUT_MAIN_SOURCE_FILE_END: File Names and DBX.
-* DBX_OUTPUT_MAIN_SOURCE_FILENAME: File Names and DBX.
-* DBX_OUTPUT_NFUN: DBX Hooks.
-* DBX_OUTPUT_RBRAC: DBX Hooks.
-* DBX_OUTPUT_SOURCE_FILENAME: File Names and DBX.
-* DBX_OUTPUT_STANDARD_TYPES: DBX Hooks.
-* DBX_REGISTER_NUMBER: All Debuggers.
-* DBX_REGPARM_STABS_CODE: DBX Options.
-* DBX_REGPARM_STABS_LETTER: DBX Options.
-* DBX_STATIC_CONST_VAR_CODE: DBX Options.
-* DBX_STATIC_STAB_DATA_SECTION: DBX Options.
-* DBX_TYPE_DECL_STABS_CODE: DBX Options.
-* DBX_USE_BINCL: DBX Options.
-* DBX_WORKING_DIRECTORY: File Names and DBX.
-* DCE, SSA based: Passes.
-* DCmode: Machine Modes.
-* De Morgan's law: Insn Canonicalizations.
-* dead code: Passes.
-* dead code elimination: Passes.
-* dead_or_set_p: define_peephole.
-* DEBUG_SYMS_TEXT: DBX Options.
-* DEBUGGER_ARG_OFFSET: All Debuggers.
-* DEBUGGER_AUTO_OFFSET: All Debuggers.
-* debugging information generation: Passes.
-* DECL_ALIGN: Declarations.
-* DECL_ANTICIPATED: Function Basics.
-* DECL_ARGUMENTS: Function Basics.
-* DECL_ARRAY_DELETE_OPERATOR_P: Function Basics.
-* DECL_ARTIFICIAL <1>: Function Basics.
-* DECL_ARTIFICIAL: Declarations.
-* DECL_ASSEMBLER_NAME: Function Basics.
-* DECL_ATTRIBUTES: Attributes.
-* DECL_BASE_CONSTRUCTOR_P: Function Basics.
-* DECL_CLASS_SCOPE_P: Declarations.
-* DECL_COMPLETE_CONSTRUCTOR_P: Function Basics.
-* DECL_COMPLETE_DESTRUCTOR_P: Function Basics.
-* DECL_CONST_MEMFUNC_P: Function Basics.
-* DECL_CONSTRUCTOR_P: Function Basics.
-* DECL_CONTEXT: Namespaces.
-* DECL_CONV_FN_P: Function Basics.
-* DECL_COPY_CONSTRUCTOR_P: Function Basics.
-* DECL_DESTRUCTOR_P: Function Basics.
-* DECL_EXTERN_C_FUNCTION_P: Function Basics.
-* DECL_EXTERNAL <1>: Function Basics.
-* DECL_EXTERNAL: Declarations.
-* DECL_FUNCTION_MEMBER_P: Function Basics.
-* DECL_FUNCTION_SCOPE_P: Declarations.
-* DECL_GLOBAL_CTOR_P: Function Basics.
-* DECL_GLOBAL_DTOR_P: Function Basics.
-* DECL_INITIAL: Declarations.
-* DECL_LINKONCE_P: Function Basics.
-* DECL_LOCAL_FUNCTION_P: Function Basics.
-* DECL_MAIN_P: Function Basics.
-* DECL_NAME <1>: Function Basics.
-* DECL_NAME <2>: Declarations.
-* DECL_NAME: Namespaces.
-* DECL_NAMESPACE_ALIAS: Namespaces.
-* DECL_NAMESPACE_SCOPE_P: Declarations.
-* DECL_NAMESPACE_STD_P: Namespaces.
-* DECL_NON_THUNK_FUNCTION_P: Function Basics.
-* DECL_NONCONVERTING_P: Function Basics.
-* DECL_NONSTATIC_MEMBER_FUNCTION_P: Function Basics.
-* DECL_OVERLOADED_OPERATOR_P: Function Basics.
-* DECL_RESULT: Function Basics.
-* DECL_SIZE: Declarations.
-* DECL_SOURCE_FILE: Declarations.
-* DECL_SOURCE_LINE: Declarations.
-* DECL_STATIC_FUNCTION_P: Function Basics.
-* DECL_STMT: Function Bodies.
-* DECL_STMT_DECL: Function Bodies.
-* DECL_THUNK_P: Function Basics.
-* DECL_VOLATILE_MEMFUNC_P: Function Basics.
-* declaration: Declarations.
-* declarations, RTL: RTL Declarations.
-* decrement_and_branch_until_zero instruction pattern: Standard Names.
-* DEFAULT_CALLER_SAVES: Caller Saves.
-* DEFAULT_GDB_EXTENSIONS: DBX Options.
-* DEFAULT_MAIN_RETURN: Misc.
-* DEFAULT_PCC_STRUCT_RETURN: Aggregate Return.
-* DEFAULT_RTX_COSTS: Costs.
-* DEFAULT_SHORT_ENUMS: Type Layout.
-* DEFAULT_SIGNED_CHAR: Type Layout.
-* define_asm_attributes: Tagging Insns.
-* define_attr: Defining Attributes.
-* define_cond_exec: Conditional Execution.
-* define_constants: Constant Definitions.
-* define_delay: Delay Slots.
-* define_expand: Expander Definitions.
-* define_function_unit: Function Units.
-* define_insn: Patterns.
-* define_insn example: Example.
-* define_insn_and_split: Insn Splitting.
-* define_peephole: define_peephole.
-* define_peephole2: define_peephole2.
-* define_split: Insn Splitting.
-* defining attributes and their values: Defining Attributes.
-* defining jump instruction patterns: Jump Patterns.
-* defining looping instruction patterns: Looping Patterns.
-* defining peephole optimizers: Peephole Definitions.
-* defining RTL sequences for code generation: Expander Definitions.
-* delay slots, defining: Delay Slots.
-* DELAY_SLOTS_FOR_EPILOGUE: Function Entry.
-* delayed branch scheduling: Passes.
-* Dependent Patterns: Dependent Patterns.
-* destructor: Function Basics.
-* destructors, output of: Initialization.
-* DFmode: Machine Modes.
-* digits in constraint: Simple Constraints.
-* DImode: Machine Modes.
-* DIR_SEPARATOR: Host Config.
-* DIR_SEPARATOR_2: Host Config.
-* directory options .md: Including Patterns.
-* disabling certain registers: Register Basics.
-* dispatch table: Dispatch Tables.
-* div: Arithmetic.
-* div and attributes: Expressions.
-* DIVDI3_LIBCALL: Library Calls.
-* division: Arithmetic.
-* divM3 instruction pattern: Standard Names.
-* divmodM4 instruction pattern: Standard Names.
-* DIVSI3_LIBCALL: Library Calls.
-* DO_BODY: Function Bodies.
-* DO_COND: Function Bodies.
-* DO_STMT: Function Bodies.
-* DOLLARS_IN_IDENTIFIERS: Misc.
-* doloop_begin instruction pattern: Standard Names.
-* doloop_end instruction pattern: Standard Names.
-* DONE: Expander Definitions.
-* DONT_REDUCE_ADDR: Costs.
-* DOUBLE_TYPE_SIZE: Type Layout.
-* driver: Driver.
-* DUMPFILE_FORMAT: Host Config.
-* DWARF2_ASM_LINE_DEBUG_INFO: SDB and DWARF.
-* DWARF2_DEBUGGING_INFO: SDB and DWARF.
-* DWARF2_FRAME_INFO: SDB and DWARF.
-* DWARF2_GENERATE_TEXT_SECTION_LABEL: SDB and DWARF.
-* DWARF2_UNWIND_INFO: Exception Region Output.
-* DWARF_CIE_DATA_ALIGNMENT: Exception Region Output.
-* DWARF_DEBUGGING_INFO: SDB and DWARF.
-* DWARF_FRAME_REGISTERS: Frame Registers.
-* DYNAMIC_CHAIN_ADDRESS: Frame Layout.
-* E in constraint: Simple Constraints.
-* earlyclobber operand: Modifiers.
-* EDOM, implicit usage: Library Calls.
-* EH_FRAME_IN_DATA_SECTION: Exception Region Output.
-* EH_FRAME_SECTION_NAME: Exception Region Output.
-* eh_return instruction pattern: Standard Names.
-* EH_RETURN_DATA_REGNO: Exception Handling.
-* EH_RETURN_HANDLER_RTX: Exception Handling.
-* EH_RETURN_STACKADJ_RTX: Exception Handling.
-* EH_USES: Function Entry.
-* ELIGIBLE_FOR_EPILOGUE_DELAY: Function Entry.
-* ELIMINABLE_REGS: Elimination.
-* ELSE_CLAUSE: Function Bodies.
-* EMIT_MODE_SET: Mode Switching.
-* EMPTY_CLASS_EXPR: Function Bodies.
-* EMPTY_FIELD_BOUNDARY: Storage Layout.
-* ENCODE_SECTION_INFO: Sections.
-* ENCODE_SECTION_INFO and address validation: Addressing Modes.
-* ENCODE_SECTION_INFO usage: Instruction Output.
-* ENDFILE_SPEC: Driver.
-* endianness: Portability.
-* enum machine_mode: Machine Modes.
-* enum reg_class: Register Classes.
-* ENUMERAL_TYPE: Types.
-* epilogue: Function Entry.
-* epilogue instruction pattern: Standard Names.
-* EPILOGUE_USES: Function Entry.
-* eq: Comparisons.
-* eq and attributes: Expressions.
-* eq_attr: Expressions.
-* EQ_EXPR: Expression trees.
-* equal: Comparisons.
-* errno, implicit usage: Library Calls.
-* escape sequences: Escape Sequences.
-* exception handling: Exception Handling.
-* exception_receiver instruction pattern: Standard Names.
-* exclamation point: Multi-Alternative.
-* exclusive-or, bitwise: Arithmetic.
-* EXIT_BODY: Misc.
-* EXIT_EXPR: Expression trees.
-* EXIT_IGNORE_STACK: Function Entry.
-* EXPAND_BUILTIN_SAVEREGS: Varargs.
-* expander definitions: Expander Definitions.
-* expr_list: Insns.
-* EXPR_STMT: Function Bodies.
-* EXPR_STMT_EXPR: Function Bodies.
-* expression: Expression trees.
-* expression codes: RTL Objects.
-* extendMN2 instruction pattern: Standard Names.
-* extensible constraints: Simple Constraints.
-* extern int target_flags: Run-time Target.
-* EXTRA_CC_MODES: Condition Code.
-* EXTRA_CONSTRAINT: Register Classes.
-* EXTRA_SECTION_FUNCTIONS: Sections.
-* EXTRA_SECTIONS: Sections.
-* EXTRA_SPECS: Driver.
-* extv instruction pattern: Standard Names.
-* extzv instruction pattern: Standard Names.
-* F in constraint: Simple Constraints.
-* FAIL: Expander Definitions.
-* FATAL_EXIT_CODE: Host Config.
-* FDL, GNU Free Documentation License: GNU Free Documentation License.
-* features, optional, in system conventions: Run-time Target.
-* ffs: Arithmetic.
-* ffsM2 instruction pattern: Standard Names.
-* FIELD_DECL: Declarations.
-* FILE_STMT: Function Bodies.
-* FILE_STMT_FILENAME: Function Bodies.
-* files and passes of the compiler: Passes.
-* final pass: Passes.
-* FINAL_PRESCAN_INSN: Instruction Output.
-* FINAL_PRESCAN_LABEL: Instruction Output.
-* FINAL_REG_PARM_STACK_SPACE: Stack Arguments.
-* final_scan_insn: Function Entry.
-* final_sequence: Instruction Output.
-* FINALIZE_PIC: PIC.
-* FIND_BASE_TERM: Addressing Modes.
-* FINI_SECTION_ASM_OP: Sections.
-* FIRST_INSN_ADDRESS: Insn Lengths.
-* FIRST_PARM_OFFSET: Frame Layout.
-* FIRST_PARM_OFFSET and virtual registers: Regs and Memory.
-* FIRST_PSEUDO_REGISTER: Register Basics.
-* FIRST_STACK_REG: Stack Registers.
-* FIRST_VIRTUAL_REGISTER: Regs and Memory.
-* fix: Conversions.
-* FIX_TRUNC_EXPR: Expression trees.
-* fix_truncMN2 instruction pattern: Standard Names.
-* fixed register: Register Basics.
-* FIXED_REGISTERS: Register Basics.
-* fixed_regs: Register Basics.
-* fixMN2 instruction pattern: Standard Names.
-* FIXUNS_TRUNC_LIKE_FIX_TRUNC: Misc.
-* fixuns_truncMN2 instruction pattern: Standard Names.
-* fixunsMN2 instruction pattern: Standard Names.
-* flags in RTL expression: Flags.
-* float: Conversions.
-* FLOAT_EXPR: Expression trees.
-* float_extend: Conversions.
-* FLOAT_LIB_COMPARE_RETURNS_BOOL (MODE, COMPARISON): Library Calls.
-* FLOAT_STORE_FLAG_VALUE: Misc.
-* float_truncate: Conversions.
-* FLOAT_TYPE_SIZE: Type Layout.
-* FLOAT_WORDS_BIG_ENDIAN: Storage Layout.
-* FLOAT_WORDS_BIG_ENDIAN, (lack of) effect on subreg: Regs and Memory.
-* floating point and cross compilation: Cross-compilation.
-* Floating Point Emulation: Target Fragment.
-* floatMN2 instruction pattern: Standard Names.
-* floatunsMN2 instruction pattern: Standard Names.
-* FOR_BODY: Function Bodies.
-* FOR_COND: Function Bodies.
-* FOR_EXPR: Function Bodies.
-* FOR_INIT_STMT: Function Bodies.
-* FOR_STMT: Function Bodies.
-* FORCE_CODE_SECTION_ALIGN: Sections.
-* FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN: Storage Layout.
-* force_reg: Standard Names.
-* frame layout: Frame Layout.
-* FRAME_GROWS_DOWNWARD: Frame Layout.
-* FRAME_GROWS_DOWNWARD and virtual registers: Regs and Memory.
-* frame_pointer_needed: Function Entry.
-* FRAME_POINTER_REGNUM: Frame Registers.
-* FRAME_POINTER_REGNUM and virtual registers: Regs and Memory.
-* FRAME_POINTER_REQUIRED: Elimination.
-* frame_pointer_rtx: Frame Registers.
-* frame_related: Flags.
-* frame_related, in insn: Flags.
-* frame_related, in mem: Flags.
-* frame_related, in reg: Flags.
-* frame_related, in symbol_ref: Flags.
-* free_machine_status: Per-Function Data.
-* ftruncM2 instruction pattern: Standard Names.
-* function: Functions.
-* function body: Function Bodies.
-* function call conventions: Interface.
-* function entry and exit: Function Entry.
-* function units, for scheduling: Function Units.
-* function-call insns: Calls.
-* FUNCTION_ARG: Register Arguments.
-* FUNCTION_ARG_ADVANCE: Register Arguments.
-* FUNCTION_ARG_BOUNDARY: Register Arguments.
-* FUNCTION_ARG_CALLEE_COPIES: Register Arguments.
-* FUNCTION_ARG_PADDING: Register Arguments.
-* FUNCTION_ARG_PARTIAL_NREGS: Register Arguments.
-* FUNCTION_ARG_PASS_BY_REFERENCE: Register Arguments.
-* FUNCTION_ARG_REG_LITTLE_ENDIAN: Register Arguments.
-* FUNCTION_ARG_REGNO_P: Register Arguments.
-* FUNCTION_BOUNDARY: Storage Layout.
-* FUNCTION_DECL: Functions.
-* FUNCTION_INCOMING_ARG: Register Arguments.
-* FUNCTION_MODE: Misc.
-* FUNCTION_OK_FOR_SIBCALL: Tail Calls.
-* FUNCTION_OUTGOING_VALUE: Scalar Return.
-* FUNCTION_PROFILER: Profiling.
-* FUNCTION_TYPE: Types.
-* FUNCTION_VALUE: Scalar Return.
-* FUNCTION_VALUE_REGNO_P: Scalar Return.
-* functions, leaf: Leaf Functions.
-* fundamental type: Types.
-* g in constraint: Simple Constraints.
-* G in constraint: Simple Constraints.
-* GCC and portability: Portability.
-* GCC_DRIVER_HOST_INITIALIZATION: Host Config.
-* GCOV_TYPE_SIZE: Type Layout.
-* ge: Comparisons.
-* ge and attributes: Expressions.
-* GE_EXPR: Expression trees.
-* GEN_ERRNO_RTX: Library Calls.
-* gencodes: Passes.
-* genconfig: Passes.
-* general_operand: RTL Template.
-* GENERAL_REGS: Register Classes.
-* generating assembler output: Output Statement.
-* generating insns: RTL Template.
-* genflags: Passes.
-* get_attr: Expressions.
-* get_attr_length: Insn Lengths.
-* GET_CLASS_NARROWEST_MODE: Machine Modes.
-* GET_CODE: RTL Objects.
-* get_frame_size: Elimination.
-* get_insns: Insns.
-* get_last_insn: Insns.
-* GET_MODE: Machine Modes.
-* GET_MODE_ALIGNMENT: Machine Modes.
-* GET_MODE_BITSIZE: Machine Modes.
-* GET_MODE_CLASS: Machine Modes.
-* GET_MODE_MASK: Machine Modes.
-* GET_MODE_NAME: Machine Modes.
-* GET_MODE_NUNITS: Machine Modes.
-* GET_MODE_SIZE: Machine Modes.
-* GET_MODE_UNIT_SIZE: Machine Modes.
-* GET_MODE_WIDER_MODE: Machine Modes.
-* GET_RTX_CLASS: RTL Classes.
-* GET_RTX_FORMAT: RTL Classes.
-* GET_RTX_LENGTH: RTL Classes.
-* geu: Comparisons.
-* geu and attributes: Expressions.
-* global common subexpression elimination: Passes.
-* global register allocation: Passes.
-* GLOBAL_INIT_PRIORITY: Function Basics.
-* GO_IF_LEGITIMATE_ADDRESS: Addressing Modes.
-* GO_IF_MODE_DEPENDENT_ADDRESS: Addressing Modes.
-* GOTO_DESTINATION: Function Bodies.
-* GOTO_FAKE_P: Function Bodies.
-* GOTO_STMT: Function Bodies.
-* greater than: Comparisons.
-* gt: Comparisons.
-* gt and attributes: Expressions.
-* GT_EXPR: Expression trees.
-* gtu: Comparisons.
-* gtu and attributes: Expressions.
-* H in constraint: Simple Constraints.
-* HANDLE_PRAGMA: Misc.
-* HANDLE_PRAGMA_PACK_PUSH_POP: Misc.
-* HANDLE_SYSV_PRAGMA: Misc.
-* HANDLER: Function Bodies.
-* HANDLER_BODY: Function Bodies.
-* HANDLER_PARMS: Function Bodies.
-* hard registers: Regs and Memory.
-* HARD_FRAME_POINTER_REGNUM: Frame Registers.
-* HARD_REGNO_CALL_PART_CLOBBERED: Register Basics.
-* HARD_REGNO_CALLER_SAVE_MODE: Caller Saves.
-* HARD_REGNO_MODE_OK: Values in Registers.
-* HARD_REGNO_NREGS: Values in Registers.
-* HAS_INIT_SECTION: Macros for Initialization.
-* HAVE_DOS_BASED_FILE_SYSTEM: Host Config.
-* HAVE_POST_DECREMENT: Addressing Modes.
-* HAVE_POST_INCREMENT: Addressing Modes.
-* HAVE_POST_MODIFY_DISP: Addressing Modes.
-* HAVE_POST_MODIFY_REG: Addressing Modes.
-* HAVE_PRE_DECREMENT: Addressing Modes.
-* HAVE_PRE_INCREMENT: Addressing Modes.
-* HAVE_PRE_MODIFY_DISP: Addressing Modes.
-* HAVE_PRE_MODIFY_REG: Addressing Modes.
-* HCmode: Machine Modes.
-* HFmode: Machine Modes.
-* high: Constants.
-* HImode: Machine Modes.
-* HImode, in insn: Insns.
-* host makefile fragment: Host Fragment.
-* HOST_BIT_BUCKET: Host Config.
-* HOST_EXECUTABLE_SUFFIX: Host Config.
-* HOST_OBJECT_SUFFIX: Host Config.
-* I in constraint: Simple Constraints.
-* i in constraint: Simple Constraints.
-* IBM_FLOAT_FORMAT: Storage Layout.
-* identifier: Identifiers.
-* IDENTIFIER_LENGTH: Identifiers.
-* IDENTIFIER_NODE: Identifiers.
-* IDENTIFIER_OPNAME_P: Identifiers.
-* IDENTIFIER_POINTER: Identifiers.
-* IDENTIFIER_TYPENAME_P: Identifiers.
-* IEEE_FLOAT_FORMAT: Storage Layout.
-* if conversion: Passes.
-* IF_COND: Function Bodies.
-* IF_STMT: Function Bodies.
-* if_then_else: Comparisons.
-* if_then_else and attributes: Expressions.
-* if_then_else usage: Side Effects.
-* IFCVT_MODIFY_CANCEL: Misc.
-* IFCVT_MODIFY_FINAL: Misc.
-* IFCVT_MODIFY_INSN: Misc.
-* IFCVT_MODIFY_TESTS: Misc.
-* IMAGPART_EXPR: Expression trees.
-* immediate_operand: RTL Template.
-* IMMEDIATE_PREFIX: Instruction Output.
-* in_data: Sections.
-* in_struct: Flags.
-* in_struct, in code_label: Flags.
-* in_struct, in insn: Flags.
-* in_struct, in label_ref: Flags.
-* in_struct, in mem: Flags.
-* in_struct, in reg: Flags.
-* in_struct, in subreg: Flags.
-* in_text: Sections.
-* include: Including Patterns.
-* INCLUDE_DEFAULTS: Driver.
-* inclusive-or, bitwise: Arithmetic.
-* INCOMING_FRAME_SP_OFFSET: Frame Layout.
-* INCOMING_REGNO: Register Basics.
-* INCOMING_RETURN_ADDR_RTX: Frame Layout.
-* INDEX_REG_CLASS: Register Classes.
-* indirect_jump instruction pattern: Standard Names.
-* INDIRECT_REF: Expression trees.
-* INIT_CUMULATIVE_ARGS: Register Arguments.
-* INIT_CUMULATIVE_INCOMING_ARGS: Register Arguments.
-* INIT_CUMULATIVE_LIBCALL_ARGS: Register Arguments.
-* INIT_ENVIRONMENT: Driver.
-* INIT_EXPANDERS: Per-Function Data.
-* INIT_EXPR: Expression trees.
-* init_machine_status: Per-Function Data.
-* INIT_SECTION_ASM_OP <1>: Macros for Initialization.
-* INIT_SECTION_ASM_OP: Sections.
-* INIT_TARGET_OPTABS: Library Calls.
-* INITIAL_ELIMINATION_OFFSET: Elimination.
-* INITIAL_FRAME_POINTER_OFFSET: Elimination.
-* initialization routines: Initialization.
-* INITIALIZE_TRAMPOLINE: Trampolines.
-* inline on rtx, automatic: Passes.
-* inline on trees, automatic: Passes.
-* inlining: Target Attributes.
-* insn: Insns.
-* insn and /f: Flags.
-* insn and /i: Flags.
-* insn and /j: Flags.
-* insn and /s: Flags.
-* insn and /u: Flags.
-* insn and /v: Flags.
-* insn attributes: Insn Attributes.
-* insn canonicalization: Insn Canonicalizations.
-* insn includes: Including Patterns.
-* insn lengths, computing: Insn Lengths.
-* insn splitting: Insn Splitting.
-* insn-attr.h: Defining Attributes.
-* INSN_ANNULLED_BRANCH_P: Flags.
-* INSN_CACHE_DEPTH: Trampolines.
-* INSN_CACHE_LINE_WIDTH: Trampolines.
-* INSN_CACHE_SIZE: Trampolines.
-* INSN_CODE: Insns.
-* INSN_DEAD_CODE_P: Flags.
-* INSN_DELETED_P: Flags.
-* INSN_FROM_TARGET_P: Flags.
-* insn_list: Insns.
-* insn_list and /c: Flags.
-* insn_list and /j: Flags.
-* INSN_REFERENCES_ARE_DELAYED: Misc.
-* INSN_SETS_ARE_DELAYED: Misc.
-* INSN_UID: Insns.
-* insns: Insns.
-* insns, generating: RTL Template.
-* insns, recognizing: RTL Template.
-* instruction attributes: Insn Attributes.
-* instruction combination: Passes.
-* instruction patterns: Patterns.
-* instruction recognizer: Passes.
-* instruction scheduling: Passes.
-* instruction splitting: Insn Splitting.
-* insv instruction pattern: Standard Names.
-* INT_TYPE_SIZE: Type Layout.
-* INTEGER_CST: Expression trees.
-* INTEGER_TYPE: Types.
-* INTEGRATE_THRESHOLD: Misc.
-* integrated: Flags.
-* integrated, in insn: Flags.
-* integrated, in reg: Flags.
-* integrated, in symbol_ref: Flags.
-* INTEL_EXTENDED_IEEE_FORMAT: Type Layout.
-* Interdependence of Patterns: Dependent Patterns.
-* interfacing to GCC output: Interface.
-* INTMAX_TYPE: Type Layout.
-* introduction: Top.
-* INVOKE__main: Macros for Initialization.
-* ior: Arithmetic.
-* ior and attributes: Expressions.
-* ior, canonicalization of: Insn Canonicalizations.
-* iorM3 instruction pattern: Standard Names.
-* IS_ASM_LOGICAL_LINE_SEPARATOR: Data Output.
-* isinf: Cross-compilation.
-* isnan: Cross-compilation.
-* jump: Flags.
-* jump instruction pattern: Standard Names.
-* jump instruction patterns: Jump Patterns.
-* jump instructions and set: Side Effects.
-* jump optimization: Passes.
-* jump threading: Passes.
-* jump, in call_insn: Flags.
-* jump, in insn: Flags.
-* jump, in insn_list: Flags.
-* jump, in mem: Flags.
-* JUMP_ALIGN: Alignment Output.
-* jump_insn: Insns.
-* JUMP_LABEL: Insns.
-* JUMP_TABLES_IN_TEXT_SECTION: Sections.
-* LABEL_ALIGN: Alignment Output.
-* LABEL_ALIGN_AFTER_BARRIER: Alignment Output.
-* LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP: Alignment Output.
-* LABEL_ALIGN_MAX_SKIP: Alignment Output.
-* LABEL_ALTERNATE_NAME: Insns.
-* LABEL_DECL: Declarations.
-* LABEL_NUSES: Insns.
-* LABEL_OUTSIDE_LOOP_P: Flags.
-* LABEL_PRESERVE_P: Flags.
-* label_ref: Constants.
-* label_ref and /s: Flags.
-* label_ref and /v: Flags.
-* label_ref, RTL sharing: Sharing.
-* LABEL_REF_NONLOCAL_P: Flags.
-* LABEL_STMT: Function Bodies.
-* LABEL_STMT_LABEL: Function Bodies.
-* large return values: Aggregate Return.
-* LAST_STACK_REG: Stack Registers.
-* LAST_VIRTUAL_REGISTER: Regs and Memory.
-* LD_FINI_SWITCH: Macros for Initialization.
-* LD_INIT_SWITCH: Macros for Initialization.
-* LDD_SUFFIX: Macros for Initialization.
-* ldexp: Cross-compilation.
-* le: Comparisons.
-* le and attributes: Expressions.
-* LE_EXPR: Expression trees.
-* leaf functions: Leaf Functions.
-* leaf_function_p: Standard Names.
-* LEAF_REG_REMAP: Leaf Functions.
-* LEAF_REGISTERS: Leaf Functions.
-* left rotate: Arithmetic.
-* left shift: Arithmetic.
-* LEGITIMATE_CONSTANT_P: Addressing Modes.
-* LEGITIMATE_PIC_OPERAND_P: PIC.
-* LEGITIMIZE_ADDRESS: Addressing Modes.
-* LEGITIMIZE_RELOAD_ADDRESS: Addressing Modes.
-* less than: Comparisons.
-* less than or equal: Comparisons.
-* leu: Comparisons.
-* leu and attributes: Expressions.
-* LIB2FUNCS_EXTRA: Target Fragment.
-* LIB_SPEC: Driver.
-* LIBCALL_VALUE: Scalar Return.
-* libgcc.a: Library Calls.
-* LIBGCC2_CFLAGS: Target Fragment.
-* LIBGCC2_WORDS_BIG_ENDIAN: Storage Layout.
-* LIBGCC_NEEDS_DOUBLE: Library Calls.
-* LIBGCC_SPEC: Driver.
-* library subroutine names: Library Calls.
-* LIBRARY_PATH_ENV: Misc.
-* LIMIT_RELOAD_CLASS: Register Classes.
-* LINK_COMMAND_SPEC: Driver.
-* LINK_COST_FREE: Flags.
-* LINK_COST_ZERO: Flags.
-* LINK_ELIMINATE_DUPLICATE_LDIRECTORIES: Driver.
-* LINK_GCC_C_SEQUENCE_SPEC: Driver.
-* LINK_LIBGCC_SPECIAL: Driver.
-* LINK_LIBGCC_SPECIAL_1: Driver.
-* LINK_SPEC: Driver.
-* linkage: Function Basics.
-* LINKER_DOES_NOT_WORK_WITH_DWARF2: SDB and DWARF.
-* list: Containers.
-* lo_sum: Arithmetic.
-* load address instruction: Simple Constraints.
-* LOAD_ARGS_REVERSED: Register Arguments.
-* LOAD_EXTEND_OP: Misc.
-* load_multiple instruction pattern: Standard Names.
-* local register allocation: Passes.
-* LOCAL_ALIGNMENT: Storage Layout.
-* LOCAL_CLASS_P: Classes.
-* LOCAL_INCLUDE_DIR: Driver.
-* LOCAL_LABEL_PREFIX: Instruction Output.
-* LOCAL_REGNO: Register Basics.
-* LOG_LINKS: Insns.
-* logical-and, bitwise: Arithmetic.
-* LONG_DOUBLE_TYPE_SIZE: Type Layout.
-* LONG_LONG_TYPE_SIZE: Type Layout.
-* LONG_TYPE_SIZE: Type Layout.
-* longjmp and automatic variables: Interface.
-* loop optimization: Passes.
-* LOOP_ALIGN: Alignment Output.
-* LOOP_ALIGN_MAX_SKIP: Alignment Output.
-* LOOP_EXPR: Expression trees.
-* looping instruction patterns: Looping Patterns.
-* LSHIFT_EXPR: Expression trees.
-* lshiftrt: Arithmetic.
-* lshiftrt and attributes: Expressions.
-* lshrM3 instruction pattern: Standard Names.
-* lt: Comparisons.
-* lt and attributes: Expressions.
-* LT_EXPR: Expression trees.
-* ltu: Comparisons.
-* m in constraint: Simple Constraints.
-* machine attributes: Target Attributes.
-* machine description macros: Target Macros.
-* machine descriptions: Machine Desc.
-* machine mode conversions: Conversions.
-* machine modes: Machine Modes.
-* machine specific constraints: Machine Constraints.
-* MACHINE_DEPENDENT_REORG: Misc.
-* macros, target description: Target Macros.
-* MAKE_DECL_ONE_ONLY (DECL): Label Output.
-* make_safe_from: Expander Definitions.
-* makefile fragment: Fragments.
-* makefile targets: Makefile.
-* mark_machine_status: Per-Function Data.
-* MASK_RETURN_ADDR: Exception Region Output.
-* match_dup <1>: define_peephole2.
-* match_dup: RTL Template.
-* match_dup and attributes: Insn Lengths.
-* match_insn: RTL Template.
-* match_insn2: RTL Template.
-* match_op_dup: RTL Template.
-* match_operand: RTL Template.
-* match_operand and attributes: Expressions.
-* match_operator: RTL Template.
-* match_par_dup: RTL Template.
-* match_parallel: RTL Template.
-* match_scratch <1>: define_peephole2.
-* match_scratch: RTL Template.
-* matching constraint: Simple Constraints.
-* matching operands: Output Template.
-* math libraries: Interface.
-* math, in RTL: Arithmetic.
-* MATH_LIBRARY: Misc.
-* MAX_BITS_PER_WORD: Storage Layout.
-* MAX_CHAR_TYPE_SIZE: Type Layout.
-* MAX_CONDITIONAL_EXECUTE: Misc.
-* MAX_FIXED_MODE_SIZE: Storage Layout.
-* MAX_INTEGER_COMPUTATION_MODE: Misc.
-* MAX_LONG_DOUBLE_TYPE_SIZE: Type Layout.
-* MAX_LONG_TYPE_SIZE: Type Layout.
-* MAX_MOVE_MAX: Misc.
-* MAX_OFILE_ALIGNMENT: Storage Layout.
-* MAX_REGS_PER_ADDRESS: Addressing Modes.
-* MAX_WCHAR_TYPE_SIZE: Type Layout.
-* maxM3 instruction pattern: Standard Names.
-* MAYBE_REG_PARM_STACK_SPACE: Stack Arguments.
-* mcount: Profiling.
-* MD_ASM_CLOBBERS: Misc.
-* MD_CAN_REDIRECT_BRANCH: Misc.
-* MD_EXEC_PREFIX: Driver.
-* MD_FALLBACK_FRAME_STATE_FOR: Exception Handling.
-* MD_STARTFILE_PREFIX: Driver.
-* MD_STARTFILE_PREFIX_1: Driver.
-* mem: Regs and Memory.
-* mem and /f: Flags.
-* mem and /j: Flags.
-* mem and /s: Flags.
-* mem and /u: Flags.
-* mem and /v: Flags.
-* mem, RTL sharing: Sharing.
-* MEM_IN_STRUCT_P: Flags.
-* MEM_KEEP_ALIAS_SET_P: Flags.
-* MEM_SCALAR_P: Flags.
-* MEM_VOLATILE_P: Flags.
-* MEMBER_TYPE_FORCES_BLK: Storage Layout.
-* memcpy, implicit usage: Library Calls.
-* memmove, implicit usage: Library Calls.
-* memory reference, nonoffsettable: Simple Constraints.
-* memory references in constraints: Simple Constraints.
-* MEMORY_MOVE_COST: Costs.
-* memset, implicit usage: Library Calls.
-* METHOD_TYPE: Types.
-* MIN_UNITS_PER_WORD: Storage Layout.
-* MINIMUM_ATOMIC_ALIGNMENT: Storage Layout.
-* minM3 instruction pattern: Standard Names.
-* minus: Arithmetic.
-* minus and attributes: Expressions.
-* minus, canonicalization of: Insn Canonicalizations.
-* MINUS_EXPR: Expression trees.
-* mod: Arithmetic.
-* mod and attributes: Expressions.
-* MODDI3_LIBCALL: Library Calls.
-* mode classes: Machine Modes.
-* mode switching: Mode Switching.
-* MODE_BASE_REG_CLASS: Register Classes.
-* MODE_CC: Machine Modes.
-* MODE_COMPLEX_FLOAT: Machine Modes.
-* MODE_COMPLEX_INT: Machine Modes.
-* MODE_FLOAT: Machine Modes.
-* MODE_FUNCTION: Machine Modes.
-* MODE_INT: Machine Modes.
-* MODE_NEEDED: Mode Switching.
-* MODE_PARTIAL_INT: Machine Modes.
-* MODE_PRIORITY_TO_MODE: Mode Switching.
-* MODE_RANDOM: Machine Modes.
-* MODES_TIEABLE_P: Values in Registers.
-* modifiers in constraints: Modifiers.
-* MODIFY_EXPR: Expression trees.
-* MODIFY_TARGET_NAME: Driver.
-* modM3 instruction pattern: Standard Names.
-* MODSI3_LIBCALL: Library Calls.
-* MOVE_BY_PIECES_P: Costs.
-* MOVE_MAX: Misc.
-* MOVE_MAX_PIECES: Costs.
-* MOVE_RATIO: Costs.
-* movM instruction pattern: Standard Names.
-* movMODEcc instruction pattern: Standard Names.
-* movstrictM instruction pattern: Standard Names.
-* movstrM instruction pattern: Standard Names.
-* MULDI3_LIBCALL: Library Calls.
-* mulhisi3 instruction pattern: Standard Names.
-* mulM3 instruction pattern: Standard Names.
-* mulqihi3 instruction pattern: Standard Names.
-* MULSI3_LIBCALL: Library Calls.
-* mulsidi3 instruction pattern: Standard Names.
-* mult: Arithmetic.
-* mult and attributes: Expressions.
-* mult, canonicalization of: Insn Canonicalizations.
-* MULT_EXPR: Expression trees.
-* MULTILIB_DEFAULTS: Driver.
-* MULTILIB_DIRNAMES: Target Fragment.
-* MULTILIB_EXCEPTIONS: Target Fragment.
-* MULTILIB_EXTRA_OPTS: Target Fragment.
-* MULTILIB_MATCHES: Target Fragment.
-* MULTILIB_OPTIONS: Target Fragment.
-* multiple alternative constraints: Multi-Alternative.
-* MULTIPLE_SYMBOL_SPACES: Misc.
-* multiplication: Arithmetic.
-* MUST_PASS_IN_STACK: Register Arguments.
-* MUST_PASS_IN_STACK, and FUNCTION_ARG: Register Arguments.
-* n in constraint: Simple Constraints.
-* N_REG_CLASSES: Register Classes.
-* name: Identifiers.
-* named patterns and conditions: Patterns.
-* names, pattern: Standard Names.
-* namespace: Namespaces.
-* namespace, class, scope: Scopes.
-* NAMESPACE_DECL <1>: Declarations.
-* NAMESPACE_DECL: Namespaces.
-* ne: Comparisons.
-* ne and attributes: Expressions.
-* NE_EXPR: Expression trees.
-* NEED_ATEXIT: Misc.
-* neg: Arithmetic.
-* neg and attributes: Expressions.
-* neg, canonicalization of: Insn Canonicalizations.
-* NEGATE_EXPR: Expression trees.
-* negM2 instruction pattern: Standard Names.
-* nested functions, trampolines for: Trampolines.
-* next_cc0_user: Jump Patterns.
-* NEXT_INSN: Insns.
-* NEXT_OBJC_RUNTIME: Library Calls.
-* nil: RTL Objects.
-* NO_BUILTIN_PTRDIFF_TYPE: Driver.
-* NO_BUILTIN_SIZE_TYPE: Driver.
-* NO_BUILTIN_WCHAR_TYPE: Driver.
-* NO_BUILTIN_WINT_TYPE: Driver.
-* NO_DBX_FUNCTION_END: DBX Hooks.
-* NO_DOLLAR_IN_LABEL: Misc.
-* NO_DOT_IN_LABEL: Misc.
-* NO_FUNCTION_CSE: Costs.
-* NO_IMPLICIT_EXTERN_C: Misc.
-* no_new_pseudos: Standard Names.
-* NO_PROFILE_COUNTERS: Profiling.
-* NO_RECURSIVE_FUNCTION_CSE: Costs.
-* NO_REGS: Register Classes.
-* NON_SAVING_SETJMP: Register Basics.
-* nonlocal_goto instruction pattern: Standard Names.
-* nonlocal_goto_receiver instruction pattern: Standard Names.
-* nonoffsettable memory reference: Simple Constraints.
-* nop instruction pattern: Standard Names.
-* NOP_EXPR: Expression trees.
-* NORMAL_MODE: Mode Switching.
-* not: Arithmetic.
-* not and attributes: Expressions.
-* not equal: Comparisons.
-* not, canonicalization of: Insn Canonicalizations.
-* note: Insns.
-* NOTE_INSN_BLOCK_BEG: Insns.
-* NOTE_INSN_BLOCK_END: Insns.
-* NOTE_INSN_DELETED: Insns.
-* NOTE_INSN_DELETED_LABEL: Insns.
-* NOTE_INSN_EH_REGION_BEG: Insns.
-* NOTE_INSN_EH_REGION_END: Insns.
-* NOTE_INSN_FUNCTION_END: Insns.
-* NOTE_INSN_LOOP_BEG: Insns.
-* NOTE_INSN_LOOP_CONT: Insns.
-* NOTE_INSN_LOOP_END: Insns.
-* NOTE_INSN_LOOP_VTOP: Insns.
-* NOTE_INSN_SETJMP: Insns.
-* NOTE_LINE_NUMBER: Insns.
-* NOTE_SOURCE_FILE: Insns.
-* NOTICE_UPDATE_CC: Condition Code.
-* NUM_MACHINE_MODES: Machine Modes.
-* NUM_MODES_FOR_MODE_SWITCHING: Mode Switching.
-* o in constraint: Simple Constraints.
-* OBJC_GEN_METHOD_LABEL: Label Output.
-* OBJC_PROLOGUE: File Framework.
-* OBJECT_FORMAT_COFF: Macros for Initialization.
-* OBJECT_FORMAT_ROSE: Macros for Initialization.
-* OFFSET_TYPE: Types.
-* offsettable address: Simple Constraints.
-* OImode: Machine Modes.
-* ON_EXIT: Misc.
-* one_cmplM2 instruction pattern: Standard Names.
-* operand access: Accessors.
-* operand constraints: Constraints.
-* operand substitution: Output Template.
-* operands: Patterns.
-* OPTIMIZATION_OPTIONS: Run-time Target.
-* OPTIMIZE_MODE_SWITCHING: Mode Switching.
-* optional hardware or system features: Run-time Target.
-* options, directory search: Including Patterns.
-* order of register allocation: Allocation Order.
-* ORDER_REGS_FOR_LOCAL_ALLOC: Allocation Order.
-* Ordering of Patterns: Pattern Ordering.
-* other register constraints: Simple Constraints.
-* OUTGOING_REG_PARM_STACK_SPACE: Stack Arguments.
-* OUTGOING_REGNO: Register Basics.
-* output of assembler code: File Framework.
-* output statements: Output Statement.
-* output templates: Output Template.
-* OUTPUT_ADDR_CONST_EXTRA: Data Output.
-* output_asm_insn: Output Statement.
-* OUTPUT_QUOTED_STRING: File Framework.
-* overflow while constant folding: Cross-compilation.
-* OVERLOAD: Functions.
-* OVERRIDE_OPTIONS: Run-time Target.
-* OVL_CURRENT: Functions.
-* OVL_NEXT: Functions.
-* p in constraint: Simple Constraints.
-* PAD_VARARGS_DOWN: Register Arguments.
-* parallel: Side Effects.
-* parameters, miscellaneous: Misc.
-* PARM_BOUNDARY: Storage Layout.
-* PARM_DECL: Declarations.
-* PARSE_LDD_OUTPUT: Macros for Initialization.
-* parsing pass: Passes.
-* passes and files of the compiler: Passes.
-* passing arguments: Interface.
-* PATH_SEPARATOR: Host Config.
-* PATTERN: Insns.
-* pattern conditions: Patterns.
-* pattern names: Standard Names.
-* Pattern Ordering: Pattern Ordering.
-* patterns: Patterns.
-* pc: Regs and Memory.
-* pc and attributes: Insn Lengths.
-* pc, RTL sharing: Sharing.
-* pc_rtx: Regs and Memory.
-* PCC_BITFIELD_TYPE_MATTERS: Storage Layout.
-* PCC_STATIC_STRUCT_RETURN: Aggregate Return.
-* PDImode: Machine Modes.
-* peephole optimization: Passes.
-* peephole optimization, RTL representation: Side Effects.
-* peephole optimizer definitions: Peephole Definitions.
-* per-function data: Per-Function Data.
-* percent sign: Output Template.
-* PIC: PIC.
-* PIC_OFFSET_TABLE_REG_CALL_CLOBBERED: PIC.
-* PIC_OFFSET_TABLE_REGNUM: PIC.
-* plus: Arithmetic.
-* plus and attributes: Expressions.
-* plus, canonicalization of: Insn Canonicalizations.
-* PLUS_EXPR: Expression trees.
-* Pmode: Misc.
-* pointer: Types.
-* POINTER_SIZE: Storage Layout.
-* POINTER_TYPE: Types.
-* POINTERS_EXTEND_UNSIGNED: Storage Layout.
-* portability: Portability.
-* position independent code: PIC.
-* post_dec: Incdec.
-* post_inc: Incdec.
-* post_modify: Incdec.
-* pragma: Misc.
-* pre_dec: Incdec.
-* PRE_GCC3_DWARF_FRAME_REGISTERS: Frame Registers.
-* pre_inc: Incdec.
-* predefined macros: Run-time Target.
-* PREDICATE_CODES: Misc.
-* predication: Conditional Execution.
-* PREFERRED_DEBUGGING_TYPE: All Debuggers.
-* PREFERRED_OUTPUT_RELOAD_CLASS: Register Classes.
-* PREFERRED_RELOAD_CLASS: Register Classes.
-* PREFERRED_STACK_BOUNDARY: Storage Layout.
-* prefetch: Side Effects.
-* prefetch instruction pattern: Standard Names.
-* PRETEND_OUTGOING_VARARGS_NAMED: Varargs.
-* prev_active_insn: define_peephole.
-* prev_cc0_setter: Jump Patterns.
-* PREV_INSN: Insns.
-* PRINT_OPERAND: Instruction Output.
-* PRINT_OPERAND_ADDRESS: Instruction Output.
-* PRINT_OPERAND_PUNCT_VALID_P: Instruction Output.
-* probe instruction pattern: Standard Names.
-* product: Arithmetic.
-* PROFILE_BEFORE_PROLOGUE: Profiling.
-* PROFILE_HOOK: Profiling.
-* profiling, code generation: Profiling.
-* program counter: Regs and Memory.
-* prologue: Function Entry.
-* prologue instruction pattern: Standard Names.
-* PROMOTE_FOR_CALL_ONLY: Storage Layout.
-* PROMOTE_FUNCTION_ARGS: Storage Layout.
-* PROMOTE_FUNCTION_RETURN: Storage Layout.
-* PROMOTE_MODE: Storage Layout.
-* PROMOTE_PROTOTYPES: Stack Arguments.
-* pseudo registers: Regs and Memory.
-* PSImode: Machine Modes.
-* PTRDIFF_TYPE: Type Layout.
-* PTRMEM_CST: Expression trees.
-* PTRMEM_CST_CLASS: Expression trees.
-* PTRMEM_CST_MEMBER: Expression trees.
-* push address instruction: Simple Constraints.
-* PUSH_ARGS: Stack Arguments.
-* push_reload: Addressing Modes.
-* PUSH_ROUNDING: Stack Arguments.
-* PUSH_ROUNDING, interaction with PREFERRED_STACK_BOUNDARY: Storage Layout.
-* pushM instruction pattern: Standard Names.
-* PUT_CODE: RTL Objects.
-* PUT_MODE: Machine Modes.
-* PUT_REG_NOTE_KIND: Insns.
-* PUT_SDB_...: SDB and DWARF.
-* QCmode: Machine Modes.
-* QFmode: Machine Modes.
-* QImode: Machine Modes.
-* QImode, in insn: Insns.
-* qualified type: Types.
-* question mark: Multi-Alternative.
-* quotient: Arithmetic.
-* r in constraint: Simple Constraints.
-* RDIV_EXPR: Expression trees.
-* READONLY_DATA_SECTION: Sections.
-* REAL_ARITHMETIC: Cross-compilation.
-* REAL_CST: Expression trees.
-* REAL_INFINITY: Cross-compilation.
-* REAL_NM_FILE_NAME: Macros for Initialization.
-* REAL_TYPE: Types.
-* REAL_VALUE_ATOF: Cross-compilation.
-* REAL_VALUE_FIX: Cross-compilation.
-* REAL_VALUE_FROM_INT: Cross-compilation.
-* REAL_VALUE_ISINF: Cross-compilation.
-* REAL_VALUE_ISNAN: Cross-compilation.
-* REAL_VALUE_LDEXP: Cross-compilation.
-* REAL_VALUE_NEGATE: Cross-compilation.
-* REAL_VALUE_RNDZINT: Cross-compilation.
-* REAL_VALUE_TO_DECIMAL: Data Output.
-* REAL_VALUE_TO_INT: Cross-compilation.
-* REAL_VALUE_TO_TARGET_DOUBLE: Data Output.
-* REAL_VALUE_TO_TARGET_LONG_DOUBLE: Data Output.
-* REAL_VALUE_TO_TARGET_SINGLE: Data Output.
-* REAL_VALUE_TRUNCATE: Cross-compilation.
-* REAL_VALUE_TYPE: Cross-compilation.
-* REAL_VALUE_UNSIGNED_FIX: Cross-compilation.
-* REAL_VALUE_UNSIGNED_RNDZINT: Cross-compilation.
-* REAL_VALUES_EQUAL: Cross-compilation.
-* REAL_VALUES_LESS: Cross-compilation.
-* REALPART_EXPR: Expression trees.
-* recog_data.operand: Instruction Output.
-* recognizing insns: RTL Template.
-* RECORD_TYPE <1>: Classes.
-* RECORD_TYPE: Types.
-* reference: Types.
-* REFERENCE_TYPE: Types.
-* reg: Regs and Memory.
-* reg and /f: Flags.
-* reg and /i: Flags.
-* reg and /s: Flags.
-* reg and /u: Flags.
-* reg and /v: Flags.
-* reg, RTL sharing: Sharing.
-* REG_ALLOC_ORDER: Allocation Order.
-* REG_BR_PRED: Insns.
-* REG_BR_PROB: Insns.
-* REG_CC_SETTER: Insns.
-* REG_CC_USER: Insns.
-* REG_CLASS_CONTENTS: Register Classes.
-* REG_CLASS_FROM_LETTER: Register Classes.
-* REG_CLASS_NAMES: Register Classes.
-* REG_DEAD: Insns.
-* REG_DEP_ANTI: Insns.
-* REG_DEP_OUTPUT: Insns.
-* REG_EQUAL: Insns.
-* REG_EQUIV: Insns.
-* REG_EXEC_COUNT: Insns.
-* REG_FRAME_RELATED_EXPR: Insns.
-* REG_FUNCTION_VALUE_P: Flags.
-* REG_INC: Insns.
-* REG_LABEL: Insns.
-* REG_LIBCALL: Insns.
-* REG_LOOP_TEST_P: Flags.
-* REG_MODE_OK_FOR_BASE_P: Addressing Modes.
-* reg_names: Instruction Output.
-* REG_NO_CONFLICT: Insns.
-* REG_NONNEG: Insns.
-* REG_NOTE_KIND: Insns.
-* REG_NOTES: Insns.
-* REG_OK_FOR_BASE_P: Addressing Modes.
-* REG_OK_FOR_INDEX_P: Addressing Modes.
-* REG_OK_STRICT: Addressing Modes.
-* REG_PARM_STACK_SPACE: Stack Arguments.
-* REG_PARM_STACK_SPACE, and FUNCTION_ARG: Register Arguments.
-* REG_POINTER: Flags.
-* REG_RETVAL: Insns.
-* REG_UNUSED: Insns.
-* REG_USERVAR_P: Flags.
-* REG_WAS_0: Insns.
-* register allocation: Passes.
-* register allocation order: Allocation Order.
-* register class definitions: Register Classes.
-* register class preference constraints: Class Preferences.
-* register class preference pass: Passes.
-* register movement: Passes.
-* register pairs: Values in Registers.
-* Register Transfer Language (RTL): RTL.
-* register usage: Registers.
-* register use analysis: Passes.
-* register-to-stack conversion: Passes.
-* REGISTER_MOVE_COST: Costs.
-* REGISTER_NAMES: Instruction Output.
-* register_operand: RTL Template.
-* REGISTER_PREFIX: Instruction Output.
-* REGISTER_TARGET_PRAGMAS: Misc.
-* registers arguments: Register Arguments.
-* registers in constraints: Simple Constraints.
-* REGNO_MODE_OK_FOR_BASE_P: Register Classes.
-* REGNO_OK_FOR_BASE_P: Register Classes.
-* REGNO_OK_FOR_INDEX_P: Register Classes.
-* REGNO_REG_CLASS: Register Classes.
-* regs_ever_live: Function Entry.
-* relative costs: Costs.
-* RELATIVE_PREFIX_NOT_LINKDIR: Driver.
-* reload pass: Regs and Memory.
-* reload_completed: Standard Names.
-* reload_in instruction pattern: Standard Names.
-* reload_in_progress: Standard Names.
-* reload_out instruction pattern: Standard Names.
-* reloading: Passes.
-* remainder: Arithmetic.
-* reordering, block: Passes.
-* representation of RTL: RTL.
-* rest_of_compilation: Passes.
-* rest_of_decl_compilation: Passes.
-* restore_stack_block instruction pattern: Standard Names.
-* restore_stack_function instruction pattern: Standard Names.
-* restore_stack_nonlocal instruction pattern: Standard Names.
-* RESULT_DECL: Declarations.
-* return: Side Effects.
-* return instruction pattern: Standard Names.
-* return values in registers: Scalar Return.
-* RETURN_ADDR_IN_PREVIOUS_FRAME: Frame Layout.
-* RETURN_ADDR_RTX: Frame Layout.
-* RETURN_ADDRESS_POINTER_REGNUM: Frame Registers.
-* RETURN_EXPR: Function Bodies.
-* RETURN_IN_MEMORY: Aggregate Return.
-* RETURN_INIT: Function Bodies.
-* RETURN_POPS_ARGS: Stack Arguments.
-* RETURN_STMT: Function Bodies.
-* returning aggregate values: Aggregate Return.
-* returning structures and unions: Interface.
-* REVERSE_CONDEXEC_PREDICATES_P: Condition Code.
-* REVERSE_CONDITION (CODE, MODE): Condition Code.
-* REVERSIBLE_CC_MODE: Condition Code.
-* right rotate: Arithmetic.
-* right shift: Arithmetic.
-* rotate: Arithmetic.
-* rotatert: Arithmetic.
-* rotlM3 instruction pattern: Standard Names.
-* rotrM3 instruction pattern: Standard Names.
-* ROUND_TYPE_ALIGN: Storage Layout.
-* ROUND_TYPE_SIZE: Storage Layout.
-* ROUND_TYPE_SIZE_UNIT: Storage Layout.
-* RSHIFT_EXPR: Expression trees.
-* RTL addition: Arithmetic.
-* RTL addition with signed saturation: Arithmetic.
-* RTL addition with unsigned saturation: Arithmetic.
-* RTL classes: RTL Classes.
-* RTL comparison: Arithmetic.
-* RTL comparison operations: Comparisons.
-* RTL constant expression types: Constants.
-* RTL constants: Constants.
-* RTL declarations: RTL Declarations.
-* RTL difference: Arithmetic.
-* RTL expression: RTL Objects.
-* RTL expressions for arithmetic: Arithmetic.
-* RTL format: RTL Classes.
-* RTL format characters: RTL Classes.
-* RTL function-call insns: Calls.
-* RTL generation: Passes.
-* RTL insn template: RTL Template.
-* RTL integers: RTL Objects.
-* RTL memory expressions: Regs and Memory.
-* RTL object types: RTL Objects.
-* RTL postdecrement: Incdec.
-* RTL postincrement: Incdec.
-* RTL predecrement: Incdec.
-* RTL preincrement: Incdec.
-* RTL register expressions: Regs and Memory.
-* RTL representation: RTL.
-* RTL side effect expressions: Side Effects.
-* RTL strings: RTL Objects.
-* RTL structure sharing assumptions: Sharing.
-* RTL subtraction: Arithmetic.
-* RTL sum: Arithmetic.
-* RTL vectors: RTL Objects.
-* RTX (See RTL): RTL Objects.
-* RTX codes, classes of: RTL Classes.
-* RTX_COSTS: Costs.
-* RTX_FRAME_RELATED_P: Flags.
-* RTX_INTEGRATED_P: Flags.
-* RTX_UNCHANGING_P: Flags.
-* run-time conventions: Interface.
-* run-time target specification: Run-time Target.
-* s in constraint: Simple Constraints.
-* same_type_p: Types.
-* save_stack_block instruction pattern: Standard Names.
-* save_stack_function instruction pattern: Standard Names.
-* save_stack_nonlocal instruction pattern: Standard Names.
-* saveable_obstack: Addressing Modes.
-* scalars, returned as values: Scalar Return.
-* SCCS_DIRECTIVE: Misc.
-* SCHED_GROUP_P: Flags.
-* scheduling, delayed branch: Passes.
-* scheduling, instruction: Passes.
-* SCmode: Machine Modes.
-* sCOND instruction pattern: Standard Names.
-* SCOPE_BEGIN_P: Function Bodies.
-* SCOPE_END_P: Function Bodies.
-* SCOPE_NULLIFIED_P: Function Bodies.
-* SCOPE_STMT: Function Bodies.
-* scratch: Regs and Memory.
-* scratch operands: Regs and Memory.
-* scratch, RTL sharing: Sharing.
-* SDB_ALLOW_FORWARD_REFERENCES: SDB and DWARF.
-* SDB_ALLOW_UNKNOWN_REFERENCES: SDB and DWARF.
-* SDB_DEBUGGING_INFO: SDB and DWARF.
-* SDB_DELIM: SDB and DWARF.
-* SDB_GENERATE_FAKE: SDB and DWARF.
-* search options: Including Patterns.
-* SECONDARY_INPUT_RELOAD_CLASS: Register Classes.
-* SECONDARY_MEMORY_NEEDED: Register Classes.
-* SECONDARY_MEMORY_NEEDED_MODE: Register Classes.
-* SECONDARY_MEMORY_NEEDED_RTX: Register Classes.
-* SECONDARY_OUTPUT_RELOAD_CLASS: Register Classes.
-* SECONDARY_RELOAD_CLASS: Register Classes.
-* SELECT_CC_MODE: Condition Code.
-* SELECT_RTX_SECTION: Sections.
-* SELECT_SECTION: Sections.
-* sequence: Side Effects.
-* set: Side Effects.
-* SET_ASM_OP: Label Output.
-* set_attr: Tagging Insns.
-* set_attr_alternative: Tagging Insns.
-* SET_DEST: Side Effects.
-* SET_IS_RETURN_P: Flags.
-* SET_SRC: Side Effects.
-* SETUP_FRAME_ADDRESSES: Frame Layout.
-* SETUP_INCOMING_VARARGS: Varargs.
-* SFmode: Machine Modes.
-* SHARED_BSS_SECTION_ASM_OP: Sections.
-* SHARED_SECTION_ASM_OP: Sections.
-* sharing of RTL components: Sharing.
-* shift: Arithmetic.
-* SHIFT_COUNT_TRUNCATED: Misc.
-* SHORT_IMMEDIATES_SIGN_EXTEND: Misc.
-* SHORT_TYPE_SIZE: Type Layout.
-* sibcall_epilogue instruction pattern: Standard Names.
-* sibling call optimization: Passes.
-* SIBLING_CALL_P: Flags.
-* sign_extend: Conversions.
-* sign_extract: Bit-Fields.
-* sign_extract, canonicalization of: Insn Canonicalizations.
-* signed division: Arithmetic.
-* signed maximum: Arithmetic.
-* signed minimum: Arithmetic.
-* SImode: Machine Modes.
-* simple constraints: Simple Constraints.
-* simplifications, arithmetic: Passes.
-* Single Static Assignment optimizations: Passes.
-* SIZE_TYPE: Type Layout.
-* SLOW_BYTE_ACCESS: Costs.
-* SLOW_UNALIGNED_ACCESS: Costs.
-* SMALL_ARG_MAX: Host Config.
-* SMALL_REGISTER_CLASSES: Register Classes.
-* SMALL_STACK: Frame Layout.
-* smax: Arithmetic.
-* smaxM3 instruction pattern: Standard Names.
-* smin: Arithmetic.
-* sminM3 instruction pattern: Standard Names.
-* smulM3_highpart instruction pattern: Standard Names.
-* SPECIAL_MODE_PREDICATES: Misc.
-* speed of instructions: Costs.
-* splitting instructions: Insn Splitting.
-* sqrt: Arithmetic.
-* sqrtM2 instruction pattern: Standard Names.
-* square root: Arithmetic.
-* ss_minus: Arithmetic.
-* ss_plus: Arithmetic.
-* ss_truncate: Conversions.
-* SSA Conditional Constant Propagation: Passes.
-* SSA DCE: Passes.
-* SSA optimizations: Passes.
-* stack arguments: Stack Arguments.
-* stack frame layout: Frame Layout.
-* STACK_BOUNDARY: Storage Layout.
-* STACK_CHECK_BUILTIN: Stack Checking.
-* STACK_CHECK_FIXED_FRAME_SIZE: Stack Checking.
-* STACK_CHECK_MAX_FRAME_SIZE: Stack Checking.
-* STACK_CHECK_MAX_VAR_SIZE: Stack Checking.
-* STACK_CHECK_PROBE_INTERVAL: Stack Checking.
-* STACK_CHECK_PROBE_LOAD: Stack Checking.
-* STACK_CHECK_PROTECT: Stack Checking.
-* STACK_DYNAMIC_OFFSET: Frame Layout.
-* STACK_DYNAMIC_OFFSET and virtual registers: Regs and Memory.
-* STACK_GROWS_DOWNWARD: Frame Layout.
-* STACK_PARMS_IN_REG_PARM_AREA: Stack Arguments.
-* STACK_POINTER_OFFSET: Frame Layout.
-* STACK_POINTER_OFFSET and virtual registers: Regs and Memory.
-* STACK_POINTER_REGNUM: Frame Registers.
-* STACK_POINTER_REGNUM and virtual registers: Regs and Memory.
-* stack_pointer_rtx: Frame Registers.
-* STACK_PUSH_CODE: Frame Layout.
-* STACK_REGS: Stack Registers.
-* STACK_SAVEAREA_MODE: Storage Layout.
-* STACK_SIZE_MODE: Storage Layout.
-* standard pattern names: Standard Names.
-* STANDARD_EXEC_PREFIX: Driver.
-* STANDARD_INCLUDE_COMPONENT: Driver.
-* STANDARD_INCLUDE_DIR: Driver.
-* STANDARD_STARTFILE_PREFIX: Driver.
-* STARTFILE_SPEC: Driver.
-* STARTING_FRAME_OFFSET: Frame Layout.
-* STARTING_FRAME_OFFSET and virtual registers: Regs and Memory.
-* statements: Function Bodies.
-* STATIC_CHAIN: Frame Registers.
-* STATIC_CHAIN_INCOMING: Frame Registers.
-* STATIC_CHAIN_INCOMING_REGNUM: Frame Registers.
-* STATIC_CHAIN_REGNUM: Frame Registers.
-* stdarg.h and register arguments: Register Arguments.
-* STDC_0_IN_SYSTEM_HEADERS: Misc.
-* STMT_EXPR: Expression trees.
-* STMT_IS_FULL_EXPR_P: Function Bodies.
-* STMT_LINENO: Function Bodies.
-* storage layout: Storage Layout.
-* STORE_FLAG_VALUE: Misc.
-* store_multiple instruction pattern: Standard Names.
-* strcpy: Storage Layout.
-* strength-reduction: Passes.
-* STRICT_ALIGNMENT: Storage Layout.
-* STRICT_ARGUMENT_NAMING: Varargs.
-* strict_low_part: RTL Declarations.
-* strict_memory_address_p: Addressing Modes.
-* STRING_CST: Expression trees.
-* STRING_POOL_ADDRESS_P: Flags.
-* STRIP_NAME_ENCODING: Sections.
-* strlenM instruction pattern: Standard Names.
-* STRUCT_VALUE: Aggregate Return.
-* STRUCT_VALUE_INCOMING: Aggregate Return.
-* STRUCT_VALUE_INCOMING_REGNUM: Aggregate Return.
-* STRUCT_VALUE_REGNUM: Aggregate Return.
-* structure value address: Aggregate Return.
-* STRUCTURE_SIZE_BOUNDARY: Storage Layout.
-* structures, returning: Interface.
-* subM3 instruction pattern: Standard Names.
-* SUBOBJECT: Function Bodies.
-* SUBOBJECT_CLEANUP: Function Bodies.
-* subreg: Regs and Memory.
-* subreg and /s: Flags.
-* subreg and /u: Flags.
-* subreg, in strict_low_part: RTL Declarations.
-* subreg, special reload handling: Regs and Memory.
-* SUBREG_BYTE: Regs and Memory.
-* SUBREG_PROMOTED_UNSIGNED_P: Flags.
-* SUBREG_PROMOTED_VAR_P: Flags.
-* SUBREG_REG: Regs and Memory.
-* SUCCESS_EXIT_CODE: Host Config.
-* SUPPORTS_INIT_PRIORITY: Macros for Initialization.
-* SUPPORTS_ONE_ONLY: Label Output.
-* SUPPORTS_WEAK: Label Output.
-* SWITCH_BODY: Function Bodies.
-* SWITCH_COND: Function Bodies.
-* SWITCH_CURTAILS_COMPILATION: Driver.
-* SWITCH_STMT: Function Bodies.
-* SWITCH_TAKES_ARG: Driver.
-* SWITCHES_NEED_SPACES: Driver.
-* symbol_ref: Constants.
-* symbol_ref and /f: Flags.
-* symbol_ref and /i: Flags.
-* symbol_ref and /u: Flags.
-* symbol_ref and /v: Flags.
-* symbol_ref, RTL sharing: Sharing.
-* SYMBOL_REF_FLAG: Flags.
-* SYMBOL_REF_FLAG, in ENCODE_SECTION_INFO: Sections.
-* SYMBOL_REF_USED: Flags.
-* SYMBOL_REF_WEAK: Flags.
-* symbolic label: Sharing.
-* SYSTEM_INCLUDE_DIR: Driver.
-* t-TARGET: Target Fragment.
-* tablejump instruction pattern: Standard Names.
-* tagging insns: Tagging Insns.
-* tail calls: Tail Calls.
-* tail recursion optimization: Passes.
-* target attributes: Target Attributes.
-* target description macros: Target Macros.
-* target functions: Target Structure.
-* target hooks: Target Structure.
-* target makefile fragment: Target Fragment.
-* target specifications: Run-time Target.
-* target-parameter-dependent code: Passes.
-* TARGET_ALLOWS_PROFILING_WITHOUT_FRAME_POINTER: Profiling.
-* TARGET_ASM_ALIGNED_DI_OP: Data Output.
-* TARGET_ASM_ALIGNED_HI_OP: Data Output.
-* TARGET_ASM_ALIGNED_SI_OP: Data Output.
-* TARGET_ASM_ALIGNED_TI_OP: Data Output.
-* TARGET_ASM_BYTE_OP: Data Output.
-* TARGET_ASM_CLOSE_PAREN: Data Output.
-* TARGET_ASM_CONSTRUCTOR: Macros for Initialization.
-* TARGET_ASM_DESTRUCTOR: Macros for Initialization.
-* TARGET_ASM_EH_FRAME_SECTION: Exception Region Output.
-* TARGET_ASM_EXCEPTION_SECTION: Exception Region Output.
-* TARGET_ASM_FUNCTION_BEGIN_EPILOGUE: Function Entry.
-* TARGET_ASM_FUNCTION_END_PROLOGUE: Function Entry.
-* TARGET_ASM_FUNCTION_EPILOGUE: Function Entry.
-* TARGET_ASM_FUNCTION_EPILOGUE and trampolines: Trampolines.
-* TARGET_ASM_FUNCTION_PROLOGUE: Function Entry.
-* TARGET_ASM_FUNCTION_PROLOGUE and trampolines: Trampolines.
-* TARGET_ASM_INTEGER: Data Output.
-* TARGET_ASM_NAMED_SECTION: File Framework.
-* TARGET_ASM_OPEN_PAREN: Data Output.
-* TARGET_ASM_UNALIGNED_DI_OP: Data Output.
-* TARGET_ASM_UNALIGNED_HI_OP: Data Output.
-* TARGET_ASM_UNALIGNED_SI_OP: Data Output.
-* TARGET_ASM_UNALIGNED_TI_OP: Data Output.
-* TARGET_ATTRIBUTE_TABLE: Target Attributes.
-* TARGET_BELL: Escape Sequences.
-* TARGET_BS: Escape Sequences.
-* TARGET_CANNOT_MODIFY_JUMPS_P: Misc.
-* TARGET_COMP_TYPE_ATTRIBUTES: Target Attributes.
-* TARGET_CR: Escape Sequences.
-* TARGET_DLLIMPORT_DECL_ATTRIBUTES: Target Attributes.
-* TARGET_EDOM: Library Calls.
-* TARGET_ESC: Escape Sequences.
-* TARGET_EXECUTABLE_SUFFIX: Misc.
-* TARGET_EXPAND_BUILTIN: Misc.
-* TARGET_FF: Escape Sequences.
-* TARGET_FLOAT_FORMAT: Storage Layout.
-* TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P: Target Attributes.
-* TARGET_HAS_F_SETLKW: Misc.
-* TARGET_HAVE_CTORS_DTORS: Macros for Initialization.
-* TARGET_HAVE_NAMED_SECTIONS: File Framework.
-* TARGET_INIT_BUILTINS: Misc.
-* TARGET_INSERT_ATTRIBUTES: Target Attributes.
-* TARGET_MEM_FUNCTIONS: Library Calls.
-* TARGET_MERGE_DECL_ATTRIBUTES: Target Attributes.
-* TARGET_MERGE_TYPE_ATTRIBUTES: Target Attributes.
-* TARGET_MS_BITFIELD_LAYOUT_P: Storage Layout.
-* TARGET_NEWLINE: Escape Sequences.
-* TARGET_OBJECT_SUFFIX: Misc.
-* TARGET_OPTION_TRANSLATE_TABLE: Driver.
-* TARGET_OPTIONS: Run-time Target.
-* TARGET_PTRMEMFUNC_VBIT_LOCATION: Type Layout.
-* TARGET_SCHED_ADJUST_COST: Scheduling.
-* TARGET_SCHED_ADJUST_PRIORITY: Scheduling.
-* TARGET_SCHED_CYCLE_DISPLAY: Scheduling.
-* TARGET_SCHED_FINISH: Scheduling.
-* TARGET_SCHED_INIT: Scheduling.
-* TARGET_SCHED_ISSUE_RATE: Scheduling.
-* TARGET_SCHED_REORDER: Scheduling.
-* TARGET_SCHED_REORDER2: Scheduling.
-* TARGET_SCHED_VARIABLE_ISSUE: Scheduling.
-* TARGET_SECTION_TYPE_FLAGS: File Framework.
-* TARGET_SET_DEFAULT_TYPE_ATTRIBUTES: Target Attributes.
-* TARGET_SWITCHES: Run-time Target.
-* TARGET_TAB: Escape Sequences.
-* TARGET_VERSION: Run-time Target.
-* TARGET_VT: Escape Sequences.
-* TARGET_VTABLE_USES_DESCRIPTORS: Type Layout.
-* targetm: Target Structure.
-* targets, makefile: Makefile.
-* TCmode: Machine Modes.
-* TEMPLATE_DECL: Declarations.
-* termination routines: Initialization.
-* text_section: Sections.
-* TEXT_SECTION: Sections.
-* TEXT_SECTION_ASM_OP: Sections.
-* TFmode: Machine Modes.
-* THEN_CLAUSE: Function Bodies.
-* THREAD_MODEL_SPEC: Driver.
-* THROW_EXPR: Expression trees.
-* THUNK_DECL: Declarations.
-* THUNK_DELTA: Declarations.
-* TImode: Machine Modes.
-* TImode, in insn: Insns.
-* tm.h macros: Target Macros.
-* top level of compiler: Passes.
-* TQFmode: Machine Modes.
-* TRADITIONAL_RETURN_FLOAT: Scalar Return.
-* TRAMPOLINE_ADJUST_ADDRESS: Trampolines.
-* TRAMPOLINE_ALIGNMENT: Trampolines.
-* TRAMPOLINE_SECTION: Trampolines.
-* TRAMPOLINE_SIZE: Trampolines.
-* TRAMPOLINE_TEMPLATE: Trampolines.
-* trampolines for nested functions: Trampolines.
-* TRANSFER_FROM_TRAMPOLINE: Trampolines.
-* trap instruction pattern: Standard Names.
-* tree <1>: Macros and Functions.
-* tree: Tree overview.
-* Tree optimization: Passes.
-* TREE_CODE: Tree overview.
-* tree_int_cst_equal: Expression trees.
-* TREE_INT_CST_HIGH: Expression trees.
-* TREE_INT_CST_LOW: Expression trees.
-* tree_int_cst_lt: Expression trees.
-* TREE_LIST: Containers.
-* TREE_OPERAND: Expression trees.
-* TREE_PUBLIC: Function Basics.
-* TREE_PURPOSE: Containers.
-* TREE_STRING_LENGTH: Expression trees.
-* TREE_STRING_POINTER: Expression trees.
-* TREE_TYPE <1>: Expression trees.
-* TREE_TYPE <2>: Function Basics.
-* TREE_TYPE <3>: Declarations.
-* TREE_TYPE: Types.
-* TREE_VALUE: Containers.
-* TREE_VEC: Containers.
-* TREE_VEC_ELT: Containers.
-* TREE_VEC_LENGTH: Containers.
-* TREE_VIA_PRIVATE: Classes.
-* TREE_VIA_PROTECTED: Classes.
-* TREE_VIA_PUBLIC: Classes.
-* Trees: Trees.
-* TRULY_NOOP_TRUNCATION: Misc.
-* TRUNC_DIV_EXPR: Expression trees.
-* TRUNC_MOD_EXPR: Expression trees.
-* truncate: Conversions.
-* truncMN2 instruction pattern: Standard Names.
-* TRUTH_AND_EXPR: Expression trees.
-* TRUTH_ANDIF_EXPR: Expression trees.
-* TRUTH_NOT_EXPR: Expression trees.
-* TRUTH_OR_EXPR: Expression trees.
-* TRUTH_ORIF_EXPR: Expression trees.
-* TRUTH_XOR_EXPR: Expression trees.
-* TRY_BLOCK: Function Bodies.
-* TRY_HANDLERS: Function Bodies.
-* TRY_STMTS: Function Bodies.
-* tstM instruction pattern: Standard Names.
-* type: Types.
-* type declaration: Declarations.
-* TYPE_ALIGN: Types.
-* TYPE_ARG_TYPES: Types.
-* TYPE_ATTRIBUTES: Attributes.
-* TYPE_BINFO: Classes.
-* TYPE_BUILT_IN: Types.
-* TYPE_CONTEXT: Types.
-* TYPE_DECL: Declarations.
-* TYPE_FIELDS <1>: Classes.
-* TYPE_FIELDS: Types.
-* TYPE_HAS_ARRAY_NEW_OPERATOR: Classes.
-* TYPE_HAS_DEFAULT_CONSTRUCTOR: Classes.
-* TYPE_HAS_MUTABLE_P: Classes.
-* TYPE_HAS_NEW_OPERATOR: Classes.
-* TYPE_MAIN_VARIANT: Types.
-* TYPE_MAX_VALUE: Types.
-* TYPE_METHOD_BASETYPE: Types.
-* TYPE_METHODS: Classes.
-* TYPE_MIN_VALUE: Types.
-* TYPE_NAME: Types.
-* TYPE_NOTHROW_P: Function Basics.
-* TYPE_OFFSET_BASETYPE: Types.
-* TYPE_OVERLOADS_ARRAY_REF: Classes.
-* TYPE_OVERLOADS_ARROW: Classes.
-* TYPE_OVERLOADS_CALL_EXPR: Classes.
-* TYPE_POLYMORPHIC_P: Classes.
-* TYPE_PRECISION: Types.
-* TYPE_PTR_P: Types.
-* TYPE_PTRFN_P: Types.
-* TYPE_PTRMEM_P: Types.
-* TYPE_PTROB_P: Types.
-* TYPE_PTROBV_P: Types.
-* TYPE_QUAL_CONST: Types.
-* TYPE_QUAL_RESTRICT: Types.
-* TYPE_QUAL_VOLATILE: Types.
-* TYPE_RAISES_EXCEPTIONS: Function Basics.
-* TYPE_SIZE: Types.
-* TYPE_UNQUALIFIED: Types.
-* TYPE_VFIELD: Classes.
-* TYPENAME_TYPE: Types.
-* TYPENAME_TYPE_FULLNAME: Types.
-* TYPEOF_TYPE: Types.
-* udiv: Arithmetic.
-* UDIVDI3_LIBCALL: Library Calls.
-* udivM3 instruction pattern: Standard Names.
-* udivmodM4 instruction pattern: Standard Names.
-* UDIVSI3_LIBCALL: Library Calls.
-* UINTMAX_TYPE: Type Layout.
-* umax: Arithmetic.
-* umaxM3 instruction pattern: Standard Names.
-* umin: Arithmetic.
-* uminM3 instruction pattern: Standard Names.
-* umod: Arithmetic.
-* UMODDI3_LIBCALL: Library Calls.
-* umodM3 instruction pattern: Standard Names.
-* UMODSI3_LIBCALL: Library Calls.
-* umulhisi3 instruction pattern: Standard Names.
-* umulM3_highpart instruction pattern: Standard Names.
-* umulqihi3 instruction pattern: Standard Names.
-* umulsidi3 instruction pattern: Standard Names.
-* unchanging: Flags.
-* unchanging, in call_insn: Flags.
-* unchanging, in insn: Flags.
-* unchanging, in reg and mem: Flags.
-* unchanging, in subreg: Flags.
-* unchanging, in symbol_ref: Flags.
-* UNION_TYPE <1>: Classes.
-* UNION_TYPE: Types.
-* unions, returning: Interface.
-* UNIQUE_SECTION: Sections.
-* UNITS_PER_WORD: Storage Layout.
-* UNKNOWN_FLOAT_FORMAT: Storage Layout.
-* UNKNOWN_TYPE: Types.
-* unreachable code: Passes.
-* unshare_all_rtl: Sharing.
-* unsigned division: Arithmetic.
-* unsigned greater than: Comparisons.
-* unsigned less than: Comparisons.
-* unsigned minimum and maximum: Arithmetic.
-* unsigned_fix: Conversions.
-* unsigned_float: Conversions.
-* unspec: Side Effects.
-* unspec_volatile: Side Effects.
-* untyped_call instruction pattern: Standard Names.
-* untyped_return instruction pattern: Standard Names.
-* UPDATE_PATH_HOST_CANONICALIZE (PATH): Host Config.
-* us_minus: Arithmetic.
-* us_plus: Arithmetic.
-* us_truncate: Conversions.
-* use: Side Effects.
-* USE_C_ALLOCA: Host Config.
-* USE_LOAD_POST_DECREMENT: Costs.
-* USE_LOAD_POST_INCREMENT: Costs.
-* USE_LOAD_PRE_DECREMENT: Costs.
-* USE_LOAD_PRE_INCREMENT: Costs.
-* USE_STORE_POST_DECREMENT: Costs.
-* USE_STORE_POST_INCREMENT: Costs.
-* USE_STORE_PRE_DECREMENT: Costs.
-* USE_STORE_PRE_INCREMENT: Costs.
-* used: Flags.
-* used, in symbol_ref: Flags.
-* USER_LABEL_PREFIX: Instruction Output.
-* USING_DECL: Declarations.
-* USING_STMT: Function Bodies.
-* V in constraint: Simple Constraints.
-* values, returned by functions: Scalar Return.
-* VAR_DECL <1>: Expression trees.
-* VAR_DECL: Declarations.
-* varargs implementation: Varargs.
-* variable: Declarations.
-* VAX_FLOAT_FORMAT: Storage Layout.
-* vec_concat: Vector Operations.
-* vec_const: Vector Operations.
-* vec_duplicate: Vector Operations.
-* vec_merge: Vector Operations.
-* vec_select: Vector Operations.
-* vector: Containers.
-* vector operations: Vector Operations.
-* VECTOR_CST: Expression trees.
-* VECTOR_MODE_SUPPORTED_P: Storage Layout.
-* VIRTUAL_INCOMING_ARGS_REGNUM: Regs and Memory.
-* VIRTUAL_OUTGOING_ARGS_REGNUM: Regs and Memory.
-* VIRTUAL_STACK_DYNAMIC_REGNUM: Regs and Memory.
-* VIRTUAL_STACK_VARS_REGNUM: Regs and Memory.
-* VMS: Host Config.
-* VMS_DEBUGGING_INFO: VMS Debug.
-* VOID_TYPE: Types.
-* VOIDmode: Machine Modes.
-* volatil: Flags.
-* volatil, in insn: Flags.
-* volatil, in label_ref: Flags.
-* volatil, in mem: Flags.
-* volatil, in reg: Flags.
-* volatil, in symbol_ref: Flags.
-* volatile memory references: Flags.
-* voting between constraint alternatives: Class Preferences.
-* VTABLE_REF: Expression trees.
-* WCHAR_TYPE: Type Layout.
-* WCHAR_TYPE_SIZE: Type Layout.
-* which_alternative: Output Statement.
-* WHILE_BODY: Function Bodies.
-* WHILE_COND: Function Bodies.
-* WHILE_STMT: Function Bodies.
-* WIDEST_HARDWARE_FP_SIZE: Type Layout.
-* WINT_TYPE: Type Layout.
-* word_mode: Machine Modes.
-* WORD_REGISTER_OPERATIONS: Misc.
-* WORD_SWITCH_TAKES_ARG: Driver.
-* WORDS_BIG_ENDIAN: Storage Layout.
-* WORDS_BIG_ENDIAN, effect on subreg: Regs and Memory.
-* X in constraint: Simple Constraints.
-* x-HOST: Host Fragment.
-* XCmode: Machine Modes.
-* XCOFF_DEBUGGING_INFO: DBX Options.
-* XEXP: Accessors.
-* XFmode: Machine Modes.
-* XINT: Accessors.
-* xm-MACHINE.h: Host Config.
-* xor: Arithmetic.
-* xor, canonicalization of: Insn Canonicalizations.
-* xorM3 instruction pattern: Standard Names.
-* XSTR: Accessors.
-* XVEC: Accessors.
-* XVECEXP: Accessors.
-* XVECLEN: Accessors.
-* XWINT: Accessors.
-* zero_extend: Conversions.
-* zero_extendMN2 instruction pattern: Standard Names.
-* zero_extract: Bit-Fields.
-* zero_extract, canonicalization of: Insn Canonicalizations.
-
-
-This is doc/gccint.info, produced by makeinfo version 4.5 from
+This is doc/gccint.info, produced by makeinfo version 4.11 from
doc/gccint.texi.
INFO-DIR-SECTION Programming
funds for GNU development.
\1f
-File: gccint.info, Node: Types, Next: Scopes, Prev: Tree overview, Up: Trees
-
-Types
-=====
-
- All types have corresponding tree nodes. However, you should not
-assume that there is exactly one tree node corresponding to each type.
-There are often several nodes each of which correspond to the same type.
-
- For the most part, different kinds of types have different tree
-codes. (For example, pointer types use a `POINTER_TYPE' code while
-arrays use an `ARRAY_TYPE' code.) However, pointers to member functions
-use the `RECORD_TYPE' code. Therefore, when writing a `switch'
-statement that depends on the code associated with a particular type,
-you should take care to handle pointers to member functions under the
-`RECORD_TYPE' case label.
-
- In C++, an array type is not qualified; rather the type of the array
-elements is qualified. This situation is reflected in the intermediate
-representation. The macros described here will always examine the
-qualification of the underlying element type when applied to an array
-type. (If the element type is itself an array, then the recursion
-continues until a non-array type is found, and the qualification of this
-type is examined.) So, for example, `CP_TYPE_CONST_P' will hold of the
-type `const int ()[7]', denoting an array of seven `int's.
-
- The following functions and macros deal with cv-qualification of
-types:
-`CP_TYPE_QUALS'
- This macro returns the set of type qualifiers applied to this type.
- This value is `TYPE_UNQUALIFIED' if no qualifiers have been
- applied. The `TYPE_QUAL_CONST' bit is set if the type is
- `const'-qualified. The `TYPE_QUAL_VOLATILE' bit is set if the
- type is `volatile'-qualified. The `TYPE_QUAL_RESTRICT' bit is set
- if the type is `restrict'-qualified.
-
-`CP_TYPE_CONST_P'
- This macro holds if the type is `const'-qualified.
-
-`CP_TYPE_VOLATILE_P'
- This macro holds if the type is `volatile'-qualified.
-
-`CP_TYPE_RESTRICT_P'
- This macro holds if the type is `restrict'-qualified.
-
-`CP_TYPE_CONST_NON_VOLATILE_P'
- This predicate holds for a type that is `const'-qualified, but
- _not_ `volatile'-qualified; other cv-qualifiers are ignored as
- well: only the `const'-ness is tested.
-
-`TYPE_MAIN_VARIANT'
- This macro returns the unqualified version of a type. It may be
- applied to an unqualified type, but it is not always the identity
- function in that case.
-
- A few other macros and functions are usable with all types:
-`TYPE_SIZE'
- The number of bits required to represent the type, represented as
- an `INTEGER_CST'. For an incomplete type, `TYPE_SIZE' will be
- `NULL_TREE'.
-
-`TYPE_ALIGN'
- The alignment of the type, in bits, represented as an `int'.
-
-`TYPE_NAME'
- This macro returns a declaration (in the form of a `TYPE_DECL') for
- the type. (Note this macro does _not_ return a `IDENTIFIER_NODE',
- as you might expect, given its name!) You can look at the
- `DECL_NAME' of the `TYPE_DECL' to obtain the actual name of the
- type. The `TYPE_NAME' will be `NULL_TREE' for a type that is not
- a built-in type, the result of a typedef, or a named class type.
-
-`CP_INTEGRAL_TYPE'
- This predicate holds if the type is an integral type. Notice that
- in C++, enumerations are _not_ integral types.
-
-`ARITHMETIC_TYPE_P'
- This predicate holds if the type is an integral type (in the C++
- sense) or a floating point type.
-
-`CLASS_TYPE_P'
- This predicate holds for a class-type.
-
-`TYPE_BUILT_IN'
- This predicate holds for a built-in type.
-
-`TYPE_PTRMEM_P'
- This predicate holds if the type is a pointer to data member.
-
-`TYPE_PTR_P'
- This predicate holds if the type is a pointer type, and the
- pointee is not a data member.
-
-`TYPE_PTRFN_P'
- This predicate holds for a pointer to function type.
-
-`TYPE_PTROB_P'
- This predicate holds for a pointer to object type. Note however
- that it does not hold for the generic pointer to object type `void
- *'. You may use `TYPE_PTROBV_P' to test for a pointer to object
- type as well as `void *'.
-
-`same_type_p'
- This predicate takes two types as input, and holds if they are the
- same type. For example, if one type is a `typedef' for the other,
- or both are `typedef's for the same type. This predicate also
- holds if the two trees given as input are simply copies of one
- another; i.e., there is no difference between them at the source
- level, but, for whatever reason, a duplicate has been made in the
- representation. You should never use `==' (pointer equality) to
- compare types; always use `same_type_p' instead.
-
- Detailed below are the various kinds of types, and the macros that
-can be used to access them. Although other kinds of types are used
-elsewhere in G++, the types described here are the only ones that you
-will encounter while examining the intermediate representation.
-
-`VOID_TYPE'
- Used to represent the `void' type.
-
-`INTEGER_TYPE'
- Used to represent the various integral types, including `char',
- `short', `int', `long', and `long long'. This code is not used
- for enumeration types, nor for the `bool' type. Note that GCC's
- `CHAR_TYPE' node is _not_ used to represent `char'. The
- `TYPE_PRECISION' is the number of bits used in the representation,
- represented as an `unsigned int'. (Note that in the general case
- this is not the same value as `TYPE_SIZE'; suppose that there were
- a 24-bit integer type, but that alignment requirements for the ABI
- required 32-bit alignment. Then, `TYPE_SIZE' would be an
- `INTEGER_CST' for 32, while `TYPE_PRECISION' would be 24.) The
- integer type is unsigned if `TREE_UNSIGNED' holds; otherwise, it
- is signed.
-
- The `TYPE_MIN_VALUE' is an `INTEGER_CST' for the smallest integer
- that may be represented by this type. Similarly, the
- `TYPE_MAX_VALUE' is an `INTEGER_CST' for the largest integer that
- may be represented by this type.
-
-`REAL_TYPE'
- Used to represent the `float', `double', and `long double' types.
- The number of bits in the floating-point representation is given
- by `TYPE_PRECISION', as in the `INTEGER_TYPE' case.
-
-`COMPLEX_TYPE'
- Used to represent GCC built-in `__complex__' data types. The
- `TREE_TYPE' is the type of the real and imaginary parts.
-
-`ENUMERAL_TYPE'
- Used to represent an enumeration type. The `TYPE_PRECISION' gives
- (as an `int'), the number of bits used to represent the type. If
- there are no negative enumeration constants, `TREE_UNSIGNED' will
- hold. The minimum and maximum enumeration constants may be
- obtained with `TYPE_MIN_VALUE' and `TYPE_MAX_VALUE', respectively;
- each of these macros returns an `INTEGER_CST'.
-
- The actual enumeration constants themselves may be obtained by
- looking at the `TYPE_VALUES'. This macro will return a
- `TREE_LIST', containing the constants. The `TREE_PURPOSE' of each
- node will be an `IDENTIFIER_NODE' giving the name of the constant;
- the `TREE_VALUE' will be an `INTEGER_CST' giving the value
- assigned to that constant. These constants will appear in the
- order in which they were declared. The `TREE_TYPE' of each of
- these constants will be the type of enumeration type itself.
-
-`BOOLEAN_TYPE'
- Used to represent the `bool' type.
-
-`POINTER_TYPE'
- Used to represent pointer types, and pointer to data member types.
- The `TREE_TYPE' gives the type to which this type points. If the
- type is a pointer to data member type, then `TYPE_PTRMEM_P' will
- hold. For a pointer to data member type of the form `T X::*',
- `TYPE_PTRMEM_CLASS_TYPE' will be the type `X', while
- `TYPE_PTRMEM_POINTED_TO_TYPE' will be the type `T'.
-
-`REFERENCE_TYPE'
- Used to represent reference types. The `TREE_TYPE' gives the type
- to which this type refers.
-
-`FUNCTION_TYPE'
- Used to represent the type of non-member functions and of static
- member functions. The `TREE_TYPE' gives the return type of the
- function. The `TYPE_ARG_TYPES' are a `TREE_LIST' of the argument
- types. The `TREE_VALUE' of each node in this list is the type of
- the corresponding argument; the `TREE_PURPOSE' is an expression
- for the default argument value, if any. If the last node in the
- list is `void_list_node' (a `TREE_LIST' node whose `TREE_VALUE' is
- the `void_type_node'), then functions of this type do not take
- variable arguments. Otherwise, they do take a variable number of
- arguments.
-
- Note that in C (but not in C++) a function declared like `void f()'
- is an unprototyped function taking a variable number of arguments;
- the `TYPE_ARG_TYPES' of such a function will be `NULL'.
-
-`METHOD_TYPE'
- Used to represent the type of a non-static member function. Like a
- `FUNCTION_TYPE', the return type is given by the `TREE_TYPE'. The
- type of `*this', i.e., the class of which functions of this type
- are a member, is given by the `TYPE_METHOD_BASETYPE'. The
- `TYPE_ARG_TYPES' is the parameter list, as for a `FUNCTION_TYPE',
- and includes the `this' argument.
-
-`ARRAY_TYPE'
- Used to represent array types. The `TREE_TYPE' gives the type of
- the elements in the array. If the array-bound is present in the
- type, the `TYPE_DOMAIN' is an `INTEGER_TYPE' whose
- `TYPE_MIN_VALUE' and `TYPE_MAX_VALUE' will be the lower and upper
- bounds of the array, respectively. The `TYPE_MIN_VALUE' will
- always be an `INTEGER_CST' for zero, while the `TYPE_MAX_VALUE'
- will be one less than the number of elements in the array, i.e.,
- the highest value which may be used to index an element in the
- array.
-
-`RECORD_TYPE'
- Used to represent `struct' and `class' types, as well as pointers
- to member functions and similar constructs in other languages.
- `TYPE_FIELDS' contains the items contained in this type, each of
- which can be a `FIELD_DECL', `VAR_DECL', `CONST_DECL', or
- `TYPE_DECL'. You may not make any assumptions about the ordering
- of the fields in the type or whether one or more of them overlap.
- If `TYPE_PTRMEMFUNC_P' holds, then this type is a pointer-to-member
- type. In that case, the `TYPE_PTRMEMFUNC_FN_TYPE' is a
- `POINTER_TYPE' pointing to a `METHOD_TYPE'. The `METHOD_TYPE' is
- the type of a function pointed to by the pointer-to-member
- function. If `TYPE_PTRMEMFUNC_P' does not hold, this type is a
- class type. For more information, see *note Classes::.
-
-`UNION_TYPE'
- Used to represent `union' types. Similar to `RECORD_TYPE' except
- that all `FIELD_DECL' nodes in `TYPE_FIELD' start at bit position
+File: gccint.info, Node: Exception Handling, Next: Stack Checking, Prev: Frame Layout, Up: Stack and Calling
+
+10.10.2 Exception Handling Support
+----------------------------------
+
+`EH_RETURN_DATA_REGNO (N)'
+ A C expression whose value is the Nth register number used for
+ data by exception handlers, or `INVALID_REGNUM' if fewer than N
+ registers are usable.
+
+ The exception handling library routines communicate with the
+ exception handlers via a set of agreed upon registers. Ideally
+ these registers should be call-clobbered; it is possible to use
+ call-saved registers, but may negatively impact code size. The
+ target must support at least 2 data registers, but should define 4
+ if there are enough free registers.
+
+ You must define this macro if you want to support call frame
+ exception handling like that provided by DWARF 2.
+
+`EH_RETURN_STACKADJ_RTX'
+ A C expression whose value is RTL representing a location in which
+ to store a stack adjustment to be applied before function return.
+ This is used to unwind the stack to an exception handler's call
+ frame. It will be assigned zero on code paths that return
+ normally.
+
+ Typically this is a call-clobbered hard register that is otherwise
+ untouched by the epilogue, but could also be a stack slot.
+
+ You must define this macro if you want to support call frame
+ exception handling like that provided by DWARF 2.
+
+`EH_RETURN_HANDLER_RTX'
+ A C expression whose value is RTL representing a location in which
+ to store the address of an exception handler to which we should
+ return. It will not be assigned on code paths that return
+ normally.
+
+ Typically this is the location in the call frame at which the
+ normal return address is stored. For targets that return by
+ popping an address off the stack, this might be a memory address
+ just below the _target_ call frame rather than inside the current
+ call frame. `EH_RETURN_STACKADJ_RTX' will have already been
+ assigned, so it may be used to calculate the location of the
+ target call frame.
+
+ Some targets have more complex requirements than storing to an
+ address calculable during initial code generation. In that case
+ the `eh_return' instruction pattern should be used instead.
+
+ If you want to support call frame exception handling, you must
+ define either this macro or the `eh_return' instruction pattern.
+
+`ASM_PREFERRED_EH_DATA_FORMAT(CODE, GLOBAL)'
+ This macro chooses the encoding of pointers embedded in the
+ exception handling sections. If at all possible, this should be
+ defined such that the exception handling section will not require
+ dynamic relocations, and so may be read-only.
+
+ CODE is 0 for data, 1 for code labels, 2 for function pointers.
+ GLOBAL is true if the symbol may be affected by dynamic
+ relocations. The macro should return a combination of the
+ `DW_EH_PE_*' defines as found in `dwarf2.h'.
+
+ If this macro is not defined, pointers will not be encoded but
+ represented directly.
+
+`ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX(FILE, ENCODING, SIZE, ADDR, DONE)'
+ This macro allows the target to emit whatever special magic is
+ required to represent the encoding chosen by
+ `ASM_PREFERRED_EH_DATA_FORMAT'. Generic code takes care of
+ pc-relative and indirect encodings; this must be defined if the
+ target uses text-relative or data-relative encodings.
+
+ This is a C statement that branches to DONE if the format was
+ handled. ENCODING is the format chosen, SIZE is the number of
+ bytes that the format occupies, ADDR is the `SYMBOL_REF' to be
+ emitted.
+
+`MD_FALLBACK_FRAME_STATE_FOR(CONTEXT, FS, SUCCESS)'
+ This macro allows the target to add cpu and operating system
+ specific code to the call-frame unwinder for use when there is no
+ unwind data available. The most common reason to implement this
+ macro is to unwind through signal frames.
+
+ This macro is called from `uw_frame_state_for' in `unwind-dw2.c'
+ and `unwind-ia64.c'. CONTEXT is an `_Unwind_Context'; FS is an
+ `_Unwind_FrameState'. Examine `context->ra' for the address of
+ the code being executed and `context->cfa' for the stack pointer
+ value. If the frame can be decoded, the register save addresses
+ should be updated in FS and the macro should branch to SUCCESS.
+ If the frame cannot be decoded, the macro should do nothing.
+
+\1f
+File: gccint.info, Node: Stack Checking, Next: Frame Registers, Prev: Exception Handling, Up: Stack and Calling
+
+10.10.3 Specifying How Stack Checking is Done
+---------------------------------------------
+
+GCC will check that stack references are within the boundaries of the
+stack, if the `-fstack-check' is specified, in one of three ways:
+
+ 1. If the value of the `STACK_CHECK_BUILTIN' macro is nonzero, GCC
+ will assume that you have arranged for stack checking to be done at
+ appropriate places in the configuration files, e.g., in
+ `TARGET_ASM_FUNCTION_PROLOGUE'. GCC will do not other special
+ processing.
+
+ 2. If `STACK_CHECK_BUILTIN' is zero and you defined a named pattern
+ called `check_stack' in your `md' file, GCC will call that pattern
+ with one argument which is the address to compare the stack value
+ against. You must arrange for this pattern to report an error if
+ the stack pointer is out of range.
+
+ 3. If neither of the above are true, GCC will generate code to
+ periodically "probe" the stack pointer using the values of the
+ macros defined below.
+
+ Normally, you will use the default values of these macros, so GCC
+will use the third approach.
+
+`STACK_CHECK_BUILTIN'
+ A nonzero value if stack checking is done by the configuration
+ files in a machine-dependent manner. You should define this macro
+ if stack checking is require by the ABI of your machine or if you
+ would like to have to stack checking in some more efficient way
+ than GCC's portable approach. The default value of this macro is
zero.
-`QUAL_UNION_TYPE'
- Used to represent part of a variant record in Ada. Similar to
- `UNION_TYPE' except that each `FIELD_DECL' has a `DECL_QUALIFIER'
- field, which contains a boolean expression that indicates whether
- the field is present in the object. The type will only have one
- field, so each field's `DECL_QUALIFIER' is only evaluated if none
- of the expressions in the previous fields in `TYPE_FIELDS' are
- nonzero. Normally these expressions will reference a field in the
- outer object using a `PLACEHOLDER_EXPR'.
-
-`UNKNOWN_TYPE'
- This node is used to represent a type the knowledge of which is
- insufficient for a sound processing.
-
-`OFFSET_TYPE'
- This node is used to represent a data member; for example a
- pointer-to-data-member is represented by a `POINTER_TYPE' whose
- `TREE_TYPE' is an `OFFSET_TYPE'. For a data member `X::m' the
- `TYPE_OFFSET_BASETYPE' is `X' and the `TREE_TYPE' is the type of
- `m'.
-
-`TYPENAME_TYPE'
- Used to represent a construct of the form `typename T::A'. The
- `TYPE_CONTEXT' is `T'; the `TYPE_NAME' is an `IDENTIFIER_NODE' for
- `A'. If the type is specified via a template-id, then
- `TYPENAME_TYPE_FULLNAME' yields a `TEMPLATE_ID_EXPR'. The
- `TREE_TYPE' is non-`NULL' if the node is implicitly generated in
- support for the implicit typename extension; in which case the
- `TREE_TYPE' is a type node for the base-class.
-
-`TYPEOF_TYPE'
- Used to represent the `__typeof__' extension. The `TYPE_FIELDS'
- is the expression the type of which is being represented.
-
- There are variables whose values represent some of the basic types.
-These include:
-`void_type_node'
- A node for `void'.
-
-`integer_type_node'
- A node for `int'.
-
-`unsigned_type_node.'
- A node for `unsigned int'.
-
-`char_type_node.'
- A node for `char'.
-
-It may sometimes be useful to compare one of these variables with a type
-in hand, using `same_type_p'.
-
-\1f
-File: gccint.info, Node: Scopes, Next: Functions, Prev: Types, Up: Trees
-
-Scopes
-======
-
- The root of the entire intermediate representation is the variable
-`global_namespace'. This is the namespace specified with `::' in C++
-source code. All other namespaces, types, variables, functions, and so
-forth can be found starting with this namespace.
-
- Besides namespaces, the other high-level scoping construct in C++ is
-the class. (Throughout this manual the term "class" is used to mean the
-types referred to in the ANSI/ISO C++ Standard as classes; these include
-types defined with the `class', `struct', and `union' keywords.)
+`STACK_CHECK_PROBE_INTERVAL'
+ An integer representing the interval at which GCC must generate
+ stack probe instructions. You will normally define this macro to
+ be no larger than the size of the "guard pages" at the end of a
+ stack area. The default value of 4096 is suitable for most
+ systems.
+
+`STACK_CHECK_PROBE_LOAD'
+ A integer which is nonzero if GCC should perform the stack probe
+ as a load instruction and zero if GCC should use a store
+ instruction. The default is zero, which is the most efficient
+ choice on most systems.
+
+`STACK_CHECK_PROTECT'
+ The number of bytes of stack needed to recover from a stack
+ overflow, for languages where such a recovery is supported. The
+ default value of 75 words should be adequate for most machines.
+
+`STACK_CHECK_MAX_FRAME_SIZE'
+ The maximum size of a stack frame, in bytes. GCC will generate
+ probe instructions in non-leaf functions to ensure at least this
+ many bytes of stack are available. If a stack frame is larger
+ than this size, stack checking will not be reliable and GCC will
+ issue a warning. The default is chosen so that GCC only generates
+ one instruction on most systems. You should normally not change
+ the default value of this macro.
+
+`STACK_CHECK_FIXED_FRAME_SIZE'
+ GCC uses this value to generate the above warning message. It
+ represents the amount of fixed frame used by a function, not
+ including space for any callee-saved registers, temporaries and
+ user variables. You need only specify an upper bound for this
+ amount and will normally use the default of four words.
+
+`STACK_CHECK_MAX_VAR_SIZE'
+ The maximum size, in bytes, of an object that GCC will place in the
+ fixed area of the stack frame when the user specifies
+ `-fstack-check'. GCC computed the default from the values of the
+ above macros and you will normally not need to override that
+ default.
+
+\1f
+File: gccint.info, Node: Frame Registers, Next: Elimination, Prev: Stack Checking, Up: Stack and Calling
+
+10.10.4 Registers That Address the Stack Frame
+----------------------------------------------
+
+This discusses registers that address the stack frame.
+
+`STACK_POINTER_REGNUM'
+ The register number of the stack pointer register, which must also
+ be a fixed register according to `FIXED_REGISTERS'. On most
+ machines, the hardware determines which register this is.
+
+`FRAME_POINTER_REGNUM'
+ The register number of the frame pointer register, which is used to
+ access automatic variables in the stack frame. On some machines,
+ the hardware determines which register this is. On other
+ machines, you can choose any register you wish for this purpose.
+
+`HARD_FRAME_POINTER_REGNUM'
+ On some machines the offset between the frame pointer and starting
+ offset of the automatic variables is not known until after register
+ allocation has been done (for example, because the saved registers
+ are between these two locations). On those machines, define
+ `FRAME_POINTER_REGNUM' the number of a special, fixed register to
+ be used internally until the offset is known, and define
+ `HARD_FRAME_POINTER_REGNUM' to be the actual hard register number
+ used for the frame pointer.
+
+ You should define this macro only in the very rare circumstances
+ when it is not possible to calculate the offset between the frame
+ pointer and the automatic variables until after register
+ allocation has been completed. When this macro is defined, you
+ must also indicate in your definition of `ELIMINABLE_REGS' how to
+ eliminate `FRAME_POINTER_REGNUM' into either
+ `HARD_FRAME_POINTER_REGNUM' or `STACK_POINTER_REGNUM'.
+
+ Do not define this macro if it would be the same as
+ `FRAME_POINTER_REGNUM'.
+
+`ARG_POINTER_REGNUM'
+ The register number of the arg pointer register, which is used to
+ access the function's argument list. On some machines, this is
+ the same as the frame pointer register. On some machines, the
+ hardware determines which register this is. On other machines,
+ you can choose any register you wish for this purpose. If this is
+ not the same register as the frame pointer register, then you must
+ mark it as a fixed register according to `FIXED_REGISTERS', or
+ arrange to be able to eliminate it (*note Elimination::).
+
+`RETURN_ADDRESS_POINTER_REGNUM'
+ The register number of the return address pointer register, which
+ is used to access the current function's return address from the
+ stack. On some machines, the return address is not at a fixed
+ offset from the frame pointer or stack pointer or argument
+ pointer. This register can be defined to point to the return
+ address on the stack, and then be converted by `ELIMINABLE_REGS'
+ into either the frame pointer or stack pointer.
+
+ Do not define this macro unless there is no other way to get the
+ return address from the stack.
+
+`STATIC_CHAIN_REGNUM'
+`STATIC_CHAIN_INCOMING_REGNUM'
+ Register numbers used for passing a function's static chain
+ pointer. If register windows are used, the register number as
+ seen by the called function is `STATIC_CHAIN_INCOMING_REGNUM',
+ while the register number as seen by the calling function is
+ `STATIC_CHAIN_REGNUM'. If these registers are the same,
+ `STATIC_CHAIN_INCOMING_REGNUM' need not be defined.
+
+ The static chain register need not be a fixed register.
+
+ If the static chain is passed in memory, these macros should not be
+ defined; instead, the next two macros should be defined.
+
+`STATIC_CHAIN'
+`STATIC_CHAIN_INCOMING'
+ If the static chain is passed in memory, these macros provide rtx
+ giving `mem' expressions that denote where they are stored.
+ `STATIC_CHAIN' and `STATIC_CHAIN_INCOMING' give the locations as
+ seen by the calling and called functions, respectively. Often the
+ former will be at an offset from the stack pointer and the latter
+ at an offset from the frame pointer.
+
+ The variables `stack_pointer_rtx', `frame_pointer_rtx', and
+ `arg_pointer_rtx' will have been initialized prior to the use of
+ these macros and should be used to refer to those items.
+
+ If the static chain is passed in a register, the two previous
+ macros should be defined instead.
+
+`DWARF_FRAME_REGISTERS'
+ This macro specifies the maximum number of hard registers that can
+ be saved in a call frame. This is used to size data structures
+ used in DWARF2 exception handling.
+
+ Prior to GCC 3.0, this macro was needed in order to establish a
+ stable exception handling ABI in the face of adding new hard
+ registers for ISA extensions. In GCC 3.0 and later, the EH ABI is
+ insulated from changes in the number of hard registers.
+ Nevertheless, this macro can still be used to reduce the runtime
+ memory requirements of the exception handling routines, which can
+ be substantial if the ISA contains a lot of registers that are not
+ call-saved.
+
+ If this macro is not defined, it defaults to
+ `FIRST_PSEUDO_REGISTER'.
+
+`PRE_GCC3_DWARF_FRAME_REGISTERS'
+ This macro is similar to `DWARF_FRAME_REGISTERS', but is provided
+ for backward compatibility in pre GCC 3.0 compiled code.
+
+ If this macro is not defined, it defaults to
+ `DWARF_FRAME_REGISTERS'.
+
+
+\1f
+File: gccint.info, Node: Elimination, Next: Stack Arguments, Prev: Frame Registers, Up: Stack and Calling
+
+10.10.5 Eliminating Frame Pointer and Arg Pointer
+-------------------------------------------------
+
+This is about eliminating the frame pointer and arg pointer.
+
+`FRAME_POINTER_REQUIRED'
+ A C expression which is nonzero if a function must have and use a
+ frame pointer. This expression is evaluated in the reload pass.
+ If its value is nonzero the function will have a frame pointer.
+
+ The expression can in principle examine the current function and
+ decide according to the facts, but on most machines the constant 0
+ or the constant 1 suffices. Use 0 when the machine allows code to
+ be generated with no frame pointer, and doing so saves some time
+ or space. Use 1 when there is no possible advantage to avoiding a
+ frame pointer.
+
+ In certain cases, the compiler does not know how to produce valid
+ code without a frame pointer. The compiler recognizes those cases
+ and automatically gives the function a frame pointer regardless of
+ what `FRAME_POINTER_REQUIRED' says. You don't need to worry about
+ them.
+
+ In a function that does not require a frame pointer, the frame
+ pointer register can be allocated for ordinary usage, unless you
+ mark it as a fixed register. See `FIXED_REGISTERS' for more
+ information.
+
+`INITIAL_FRAME_POINTER_OFFSET (DEPTH-VAR)'
+ A C statement to store in the variable DEPTH-VAR the difference
+ between the frame pointer and the stack pointer values immediately
+ after the function prologue. The value would be computed from
+ information such as the result of `get_frame_size ()' and the
+ tables of registers `regs_ever_live' and `call_used_regs'.
+
+ If `ELIMINABLE_REGS' is defined, this macro will be not be used and
+ need not be defined. Otherwise, it must be defined even if
+ `FRAME_POINTER_REQUIRED' is defined to always be true; in that
+ case, you may set DEPTH-VAR to anything.
+
+`ELIMINABLE_REGS'
+ If defined, this macro specifies a table of register pairs used to
+ eliminate unneeded registers that point into the stack frame. If
+ it is not defined, the only elimination attempted by the compiler
+ is to replace references to the frame pointer with references to
+ the stack pointer.
+
+ The definition of this macro is a list of structure
+ initializations, each of which specifies an original and
+ replacement register.
+
+ On some machines, the position of the argument pointer is not
+ known until the compilation is completed. In such a case, a
+ separate hard register must be used for the argument pointer.
+ This register can be eliminated by replacing it with either the
+ frame pointer or the argument pointer, depending on whether or not
+ the frame pointer has been eliminated.
+
+ In this case, you might specify:
+ #define ELIMINABLE_REGS \
+ {{ARG_POINTER_REGNUM, STACK_POINTER_REGNUM}, \
+ {ARG_POINTER_REGNUM, FRAME_POINTER_REGNUM}, \
+ {FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM}}
+
+ Note that the elimination of the argument pointer with the stack
+ pointer is specified first since that is the preferred elimination.
+
+`CAN_ELIMINATE (FROM-REG, TO-REG)'
+ A C expression that returns nonzero if the compiler is allowed to
+ try to replace register number FROM-REG with register number
+ TO-REG. This macro need only be defined if `ELIMINABLE_REGS' is
+ defined, and will usually be the constant 1, since most of the
+ cases preventing register elimination are things that the compiler
+ already knows about.
+
+`INITIAL_ELIMINATION_OFFSET (FROM-REG, TO-REG, OFFSET-VAR)'
+ This macro is similar to `INITIAL_FRAME_POINTER_OFFSET'. It
+ specifies the initial difference between the specified pair of
+ registers. This macro must be defined if `ELIMINABLE_REGS' is
+ defined.
+
+\1f
+File: gccint.info, Node: Stack Arguments, Next: Register Arguments, Prev: Elimination, Up: Stack and Calling
+
+10.10.6 Passing Function Arguments on the Stack
+-----------------------------------------------
+
+The macros in this section control how arguments are passed on the
+stack. See the following section for other macros that control passing
+certain arguments in registers.
+
+`PROMOTE_PROTOTYPES'
+ A C expression whose value is nonzero if an argument declared in a
+ prototype as an integral type smaller than `int' should actually
+ be passed as an `int'. In addition to avoiding errors in certain
+ cases of mismatch, it also makes for better code on certain
+ machines. If the macro is not defined in target header files, it
+ defaults to 0.
+
+`PUSH_ARGS'
+ A C expression. If nonzero, push insns will be used to pass
+ outgoing arguments. If the target machine does not have a push
+ instruction, set it to zero. That directs GCC to use an alternate
+ strategy: to allocate the entire argument block and then store the
+ arguments into it. When `PUSH_ARGS' is nonzero, `PUSH_ROUNDING'
+ must be defined too.
+
+`PUSH_ROUNDING (NPUSHED)'
+ A C expression that is the number of bytes actually pushed onto the
+ stack when an instruction attempts to push NPUSHED bytes.
+
+ On some machines, the definition
+
+ #define PUSH_ROUNDING(BYTES) (BYTES)
+
+ will suffice. But on other machines, instructions that appear to
+ push one byte actually push two bytes in an attempt to maintain
+ alignment. Then the definition should be
+
+ #define PUSH_ROUNDING(BYTES) (((BYTES) + 1) & ~1)
+
+`ACCUMULATE_OUTGOING_ARGS'
+ A C expression. If nonzero, the maximum amount of space required
+ for outgoing arguments will be computed and placed into the
+ variable `current_function_outgoing_args_size'. No space will be
+ pushed onto the stack for each call; instead, the function
+ prologue should increase the stack frame size by this amount.
+
+ Setting both `PUSH_ARGS' and `ACCUMULATE_OUTGOING_ARGS' is not
+ proper.
+
+`REG_PARM_STACK_SPACE (FNDECL)'
+ Define this macro if functions should assume that stack space has
+ been allocated for arguments even when their values are passed in
+ registers.
+
+ The value of this macro is the size, in bytes, of the area
+ reserved for arguments passed in registers for the function
+ represented by FNDECL, which can be zero if GCC is calling a
+ library function.
+
+ This space can be allocated by the caller, or be a part of the
+ machine-dependent stack frame: `OUTGOING_REG_PARM_STACK_SPACE' says
+ which.
+
+`MAYBE_REG_PARM_STACK_SPACE'
+`FINAL_REG_PARM_STACK_SPACE (CONST_SIZE, VAR_SIZE)'
+ Define these macros in addition to the one above if functions might
+ allocate stack space for arguments even when their values are
+ passed in registers. These should be used when the stack space
+ allocated for arguments in registers is not a simple constant
+ independent of the function declaration.
+
+ The value of the first macro is the size, in bytes, of the area
+ that we should initially assume would be reserved for arguments
+ passed in registers.
+
+ The value of the second macro is the actual size, in bytes, of the
+ area that will be reserved for arguments passed in registers.
+ This takes two arguments: an integer representing the number of
+ bytes of fixed sized arguments on the stack, and a tree
+ representing the number of bytes of variable sized arguments on
+ the stack.
+
+ When these macros are defined, `REG_PARM_STACK_SPACE' will only be
+ called for libcall functions, the current function, or for a
+ function being called when it is known that such stack space must
+ be allocated. In each case this value can be easily computed.
+
+ When deciding whether a called function needs such stack space,
+ and how much space to reserve, GCC uses these two macros instead of
+ `REG_PARM_STACK_SPACE'.
+
+`OUTGOING_REG_PARM_STACK_SPACE'
+ Define this if it is the responsibility of the caller to allocate
+ the area reserved for arguments passed in registers.
+
+ If `ACCUMULATE_OUTGOING_ARGS' is defined, this macro controls
+ whether the space for these arguments counts in the value of
+ `current_function_outgoing_args_size'.
+
+`STACK_PARMS_IN_REG_PARM_AREA'
+ Define this macro if `REG_PARM_STACK_SPACE' is defined, but the
+ stack parameters don't skip the area specified by it.
+
+ Normally, when a parameter is not passed in registers, it is
+ placed on the stack beyond the `REG_PARM_STACK_SPACE' area.
+ Defining this macro suppresses this behavior and causes the
+ parameter to be passed on the stack in its natural location.
+
+`RETURN_POPS_ARGS (FUNDECL, FUNTYPE, STACK-SIZE)'
+ A C expression that should indicate the number of bytes of its own
+ arguments that a function pops on returning, or 0 if the function
+ pops no arguments and the caller must therefore pop them all after
+ the function returns.
+
+ FUNDECL is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ `FUNCTION_DECL' that describes the declaration of the function.
+ From this you can obtain the `DECL_ATTRIBUTES' of the function.
+
+ FUNTYPE is a C variable whose value is a tree node that describes
+ the function in question. Normally it is a node of type
+ `FUNCTION_TYPE' that describes the data type of the function.
+ From this it is possible to obtain the data types of the value and
+ arguments (if known).
+
+ When a call to a library function is being considered, FUNDECL
+ will contain an identifier node for the library function. Thus, if
+ you need to distinguish among various library functions, you can
+ do so by their names. Note that "library function" in this
+ context means a function used to perform arithmetic, whose name is
+ known specially in the compiler and was not mentioned in the C
+ code being compiled.
+
+ STACK-SIZE is the number of bytes of arguments passed on the
+ stack. If a variable number of bytes is passed, it is zero, and
+ argument popping will always be the responsibility of the calling
+ function.
+
+ On the VAX, all functions always pop their arguments, so the
+ definition of this macro is STACK-SIZE. On the 68000, using the
+ standard calling convention, no functions pop their arguments, so
+ the value of the macro is always 0 in this case. But an
+ alternative calling convention is available in which functions
+ that take a fixed number of arguments pop them but other functions
+ (such as `printf') pop nothing (the caller pops all). When this
+ convention is in use, FUNTYPE is examined to determine whether a
+ function takes a fixed number of arguments.
+
+`CALL_POPS_ARGS (CUM)'
+ A C expression that should indicate the number of bytes a call
+ sequence pops off the stack. It is added to the value of
+ `RETURN_POPS_ARGS' when compiling a function call.
+
+ CUM is the variable in which all arguments to the called function
+ have been accumulated.
+
+ On certain architectures, such as the SH5, a call trampoline is
+ used that pops certain registers off the stack, depending on the
+ arguments that have been passed to the function. Since this is a
+ property of the call site, not of the called function,
+ `RETURN_POPS_ARGS' is not appropriate.
+
+
+\1f
+File: gccint.info, Node: Register Arguments, Next: Scalar Return, Prev: Stack Arguments, Up: Stack and Calling
+
+10.10.7 Passing Arguments in Registers
+--------------------------------------
+
+This section describes the macros which let you control how various
+types of arguments are passed in registers or how they are arranged in
+the stack.
+
+`FUNCTION_ARG (CUM, MODE, TYPE, NAMED)'
+ A C expression that controls whether a function argument is passed
+ in a register, and which register.
+
+ The arguments are CUM, which summarizes all the previous
+ arguments; MODE, the machine mode of the argument; TYPE, the data
+ type of the argument as a tree node or 0 if that is not known
+ (which happens for C support library functions); and NAMED, which
+ is 1 for an ordinary argument and 0 for nameless arguments that
+ correspond to `...' in the called function's prototype. TYPE can
+ be an incomplete type if a syntax error has previously occurred.
+
+ The value of the expression is usually either a `reg' RTX for the
+ hard register in which to pass the argument, or zero to pass the
+ argument on the stack.
+
+ For machines like the VAX and 68000, where normally all arguments
+ are pushed, zero suffices as a definition.
+
+ The value of the expression can also be a `parallel' RTX. This is
+ used when an argument is passed in multiple locations. The mode
+ of the of the `parallel' should be the mode of the entire
+ argument. The `parallel' holds any number of `expr_list' pairs;
+ each one describes where part of the argument is passed. In each
+ `expr_list' the first operand must be a `reg' RTX for the hard
+ register in which to pass this part of the argument, and the mode
+ of the register RTX indicates how large this part of the argument
+ is. The second operand of the `expr_list' is a `const_int' which
+ gives the offset in bytes into the entire argument of where this
+ part starts. As a special exception the first `expr_list' in the
+ `parallel' RTX may have a first operand of zero. This indicates
+ that the entire argument is also stored on the stack.
+
+ The last time this macro is called, it is called with `MODE ==
+ VOIDmode', and its result is passed to the `call' or `call_value'
+ pattern as operands 2 and 3 respectively.
+
+ The usual way to make the ISO library `stdarg.h' work on a machine
+ where some arguments are usually passed in registers, is to cause
+ nameless arguments to be passed on the stack instead. This is done
+ by making `FUNCTION_ARG' return 0 whenever NAMED is 0.
+
+ You may use the macro `MUST_PASS_IN_STACK (MODE, TYPE)' in the
+ definition of this macro to determine if this argument is of a
+ type that must be passed in the stack. If `REG_PARM_STACK_SPACE'
+ is not defined and `FUNCTION_ARG' returns nonzero for such an
+ argument, the compiler will abort. If `REG_PARM_STACK_SPACE' is
+ defined, the argument will be computed in the stack and then
+ loaded into a register.
+
+`MUST_PASS_IN_STACK (MODE, TYPE)'
+ Define as a C expression that evaluates to nonzero if we do not
+ know how to pass TYPE solely in registers. The file `expr.h'
+ defines a definition that is usually appropriate, refer to
+ `expr.h' for additional documentation.
+
+`FUNCTION_INCOMING_ARG (CUM, MODE, TYPE, NAMED)'
+ Define this macro if the target machine has "register windows", so
+ that the register in which a function sees an arguments is not
+ necessarily the same as the one in which the caller passed the
+ argument.
+
+ For such machines, `FUNCTION_ARG' computes the register in which
+ the caller passes the value, and `FUNCTION_INCOMING_ARG' should be
+ defined in a similar fashion to tell the function being called
+ where the arguments will arrive.
+
+ If `FUNCTION_INCOMING_ARG' is not defined, `FUNCTION_ARG' serves
+ both purposes.
+
+`FUNCTION_ARG_PARTIAL_NREGS (CUM, MODE, TYPE, NAMED)'
+ A C expression for the number of words, at the beginning of an
+ argument, that must be put in registers. The value must be zero
+ for arguments that are passed entirely in registers or that are
+ entirely pushed on the stack.
+
+ On some machines, certain arguments must be passed partially in
+ registers and partially in memory. On these machines, typically
+ the first N words of arguments are passed in registers, and the
+ rest on the stack. If a multi-word argument (a `double' or a
+ structure) crosses that boundary, its first few words must be
+ passed in registers and the rest must be pushed. This macro tells
+ the compiler when this occurs, and how many of the words should go
+ in registers.
+
+ `FUNCTION_ARG' for these arguments should return the first
+ register to be used by the caller for this argument; likewise
+ `FUNCTION_INCOMING_ARG', for the called function.
+
+`FUNCTION_ARG_PASS_BY_REFERENCE (CUM, MODE, TYPE, NAMED)'
+ A C expression that indicates when an argument must be passed by
+ reference. If nonzero for an argument, a copy of that argument is
+ made in memory and a pointer to the argument is passed instead of
+ the argument itself. The pointer is passed in whatever way is
+ appropriate for passing a pointer to that type.
+
+ On machines where `REG_PARM_STACK_SPACE' is not defined, a suitable
+ definition of this macro might be
+ #define FUNCTION_ARG_PASS_BY_REFERENCE\
+ (CUM, MODE, TYPE, NAMED) \
+ MUST_PASS_IN_STACK (MODE, TYPE)
+
+`FUNCTION_ARG_CALLEE_COPIES (CUM, MODE, TYPE, NAMED)'
+ If defined, a C expression that indicates when it is the called
+ function's responsibility to make a copy of arguments passed by
+ invisible reference. Normally, the caller makes a copy and passes
+ the address of the copy to the routine being called. When
+ `FUNCTION_ARG_CALLEE_COPIES' is defined and is nonzero, the caller
+ does not make a copy. Instead, it passes a pointer to the "live"
+ value. The called function must not modify this value. If it can
+ be determined that the value won't be modified, it need not make a
+ copy; otherwise a copy must be made.
+
+`FUNCTION_ARG_REG_LITTLE_ENDIAN'
+ If defined TRUE on a big-endian system then structure arguments
+ passed (and returned) in registers are passed in a little-endian
+ manner instead of the big-endian manner. On the HP-UX IA64 and
+ PA64 platforms structures are aligned differently then integral
+ values and setting this value to true will allow for the special
+ handling of structure arguments and return values.
+
+`CUMULATIVE_ARGS'
+ A C type for declaring a variable that is used as the first
+ argument of `FUNCTION_ARG' and other related values. For some
+ target machines, the type `int' suffices and can hold the number
+ of bytes of argument so far.
+
+ There is no need to record in `CUMULATIVE_ARGS' anything about the
+ arguments that have been passed on the stack. The compiler has
+ other variables to keep track of that. For target machines on
+ which all arguments are passed on the stack, there is no need to
+ store anything in `CUMULATIVE_ARGS'; however, the data structure
+ must exist and should not be empty, so use `int'.
+
+`INIT_CUMULATIVE_ARGS (CUM, FNTYPE, LIBNAME, INDIRECT)'
+ A C statement (sans semicolon) for initializing the variable CUM
+ for the state at the beginning of the argument list. The variable
+ has type `CUMULATIVE_ARGS'. The value of FNTYPE is the tree node
+ for the data type of the function which will receive the args, or 0
+ if the args are to a compiler support library function. The value
+ of INDIRECT is nonzero when processing an indirect call, for
+ example a call through a function pointer. The value of INDIRECT
+ is zero for a call to an explicitly named function, a library
+ function call, or when `INIT_CUMULATIVE_ARGS' is used to find
+ arguments for the function being compiled.
+
+ When processing a call to a compiler support library function,
+ LIBNAME identifies which one. It is a `symbol_ref' rtx which
+ contains the name of the function, as a string. LIBNAME is 0 when
+ an ordinary C function call is being processed. Thus, each time
+ this macro is called, either LIBNAME or FNTYPE is nonzero, but
+ never both of them at once.
+
+`INIT_CUMULATIVE_LIBCALL_ARGS (CUM, MODE, LIBNAME)'
+ Like `INIT_CUMULATIVE_ARGS' but only used for outgoing libcalls,
+ it gets a `MODE' argument instead of FNTYPE, that would be `NULL'.
+ INDIRECT would always be zero, too. If this macro is not defined,
+ `INIT_CUMULATIVE_ARGS (cum, NULL_RTX, libname, 0)' is used instead.
+
+`INIT_CUMULATIVE_INCOMING_ARGS (CUM, FNTYPE, LIBNAME)'
+ Like `INIT_CUMULATIVE_ARGS' but overrides it for the purposes of
+ finding the arguments for the function being compiled. If this
+ macro is undefined, `INIT_CUMULATIVE_ARGS' is used instead.
+
+ The value passed for LIBNAME is always 0, since library routines
+ with special calling conventions are never compiled with GCC. The
+ argument LIBNAME exists for symmetry with `INIT_CUMULATIVE_ARGS'.
+
+`FUNCTION_ARG_ADVANCE (CUM, MODE, TYPE, NAMED)'
+ A C statement (sans semicolon) to update the summarizer variable
+ CUM to advance past an argument in the argument list. The values
+ MODE, TYPE and NAMED describe that argument. Once this is done,
+ the variable CUM is suitable for analyzing the _following_
+ argument with `FUNCTION_ARG', etc.
+
+ This macro need not do anything if the argument in question was
+ passed on the stack. The compiler knows how to track the amount
+ of stack space used for arguments without any special help.
+
+`FUNCTION_ARG_PADDING (MODE, TYPE)'
+ If defined, a C expression which determines whether, and in which
+ direction, to pad out an argument with extra space. The value
+ should be of type `enum direction': either `upward' to pad above
+ the argument, `downward' to pad below, or `none' to inhibit
+ padding.
+
+ The _amount_ of padding is always just enough to reach the next
+ multiple of `FUNCTION_ARG_BOUNDARY'; this macro does not control
+ it.
+
+ This macro has a default definition which is right for most
+ systems. For little-endian machines, the default is to pad
+ upward. For big-endian machines, the default is to pad downward
+ for an argument of constant size shorter than an `int', and upward
+ otherwise.
+
+`PAD_VARARGS_DOWN'
+ If defined, a C expression which determines whether the default
+ implementation of va_arg will attempt to pad down before reading
+ the next argument, if that argument is smaller than its aligned
+ space as controlled by `PARM_BOUNDARY'. If this macro is not
+ defined, all such arguments are padded down if `BYTES_BIG_ENDIAN'
+ is true.
+
+`FUNCTION_ARG_BOUNDARY (MODE, TYPE)'
+ If defined, a C expression that gives the alignment boundary, in
+ bits, of an argument with the specified mode and type. If it is
+ not defined, `PARM_BOUNDARY' is used for all arguments.
+
+`FUNCTION_ARG_REGNO_P (REGNO)'
+ A C expression that is nonzero if REGNO is the number of a hard
+ register in which function arguments are sometimes passed. This
+ does _not_ include implicit arguments such as the static chain and
+ the structure-value address. On many machines, no registers can be
+ used for this purpose since all function arguments are pushed on
+ the stack.
+
+`LOAD_ARGS_REVERSED'
+ If defined, the order in which arguments are loaded into their
+ respective argument registers is reversed so that the last
+ argument is loaded first. This macro only affects arguments
+ passed in registers.
+
+
+\1f
+File: gccint.info, Node: Scalar Return, Next: Aggregate Return, Prev: Register Arguments, Up: Stack and Calling
+
+10.10.8 How Scalar Function Values Are Returned
+-----------------------------------------------
+
+This section discusses the macros that control returning scalars as
+values--values that can fit in registers.
+
+`TRADITIONAL_RETURN_FLOAT'
+ Define this macro if `-traditional' should not cause functions
+ declared to return `float' to convert the value to `double'.
+
+`FUNCTION_VALUE (VALTYPE, FUNC)'
+ A C expression to create an RTX representing the place where a
+ function returns a value of data type VALTYPE. VALTYPE is a tree
+ node representing a data type. Write `TYPE_MODE (VALTYPE)' to get
+ the machine mode used to represent that type. On many machines,
+ only the mode is relevant. (Actually, on most machines, scalar
+ values are returned in the same place regardless of mode).
+
+ The value of the expression is usually a `reg' RTX for the hard
+ register where the return value is stored. The value can also be a
+ `parallel' RTX, if the return value is in multiple places. See
+ `FUNCTION_ARG' for an explanation of the `parallel' form.
+
+ If `PROMOTE_FUNCTION_RETURN' is defined, you must apply the same
+ promotion rules specified in `PROMOTE_MODE' if VALTYPE is a scalar
+ type.
+
+ If the precise function being called is known, FUNC is a tree node
+ (`FUNCTION_DECL') for it; otherwise, FUNC is a null pointer. This
+ makes it possible to use a different value-returning convention
+ for specific functions when all their calls are known.
+
+ `FUNCTION_VALUE' is not used for return vales with aggregate data
+ types, because these are returned in another way. See
+ `STRUCT_VALUE_REGNUM' and related macros, below.
+
+`FUNCTION_OUTGOING_VALUE (VALTYPE, FUNC)'
+ Define this macro if the target machine has "register windows" so
+ that the register in which a function returns its value is not the
+ same as the one in which the caller sees the value.
+
+ For such machines, `FUNCTION_VALUE' computes the register in which
+ the caller will see the value. `FUNCTION_OUTGOING_VALUE' should be
+ defined in a similar fashion to tell the function where to put the
+ value.
+
+ If `FUNCTION_OUTGOING_VALUE' is not defined, `FUNCTION_VALUE'
+ serves both purposes.
+
+ `FUNCTION_OUTGOING_VALUE' is not used for return vales with
+ aggregate data types, because these are returned in another way.
+ See `STRUCT_VALUE_REGNUM' and related macros, below.
+
+`LIBCALL_VALUE (MODE)'
+ A C expression to create an RTX representing the place where a
+ library function returns a value of mode MODE. If the precise
+ function being called is known, FUNC is a tree node
+ (`FUNCTION_DECL') for it; otherwise, FUNC is a null pointer. This
+ makes it possible to use a different value-returning convention
+ for specific functions when all their calls are known.
+
+ Note that "library function" in this context means a compiler
+ support routine, used to perform arithmetic, whose name is known
+ specially by the compiler and was not mentioned in the C code being
+ compiled.
+
+ The definition of `LIBRARY_VALUE' need not be concerned aggregate
+ data types, because none of the library functions returns such
+ types.
+
+`FUNCTION_VALUE_REGNO_P (REGNO)'
+ A C expression that is nonzero if REGNO is the number of a hard
+ register in which the values of called function may come back.
+
+ A register whose use for returning values is limited to serving as
+ the second of a pair (for a value of type `double', say) need not
+ be recognized by this macro. So for most machines, this definition
+ suffices:
+
+ #define FUNCTION_VALUE_REGNO_P(N) ((N) == 0)
+
+ If the machine has register windows, so that the caller and the
+ called function use different registers for the return value, this
+ macro should recognize only the caller's register numbers.
+
+`APPLY_RESULT_SIZE'
+ Define this macro if `untyped_call' and `untyped_return' need more
+ space than is implied by `FUNCTION_VALUE_REGNO_P' for saving and
+ restoring an arbitrary return value.
+
+\1f
+File: gccint.info, Node: Aggregate Return, Next: Caller Saves, Prev: Scalar Return, Up: Stack and Calling
+
+10.10.9 How Large Values Are Returned
+-------------------------------------
+
+When a function value's mode is `BLKmode' (and in some other cases),
+the value is not returned according to `FUNCTION_VALUE' (*note Scalar
+Return::). Instead, the caller passes the address of a block of memory
+in which the value should be stored. This address is called the
+"structure value address".
+
+ This section describes how to control returning structure values in
+memory.
+
+`RETURN_IN_MEMORY (TYPE)'
+ A C expression which can inhibit the returning of certain function
+ values in registers, based on the type of value. A nonzero value
+ says to return the function value in memory, just as large
+ structures are always returned. Here TYPE will be a C expression
+ of type `tree', representing the data type of the value.
+
+ Note that values of mode `BLKmode' must be explicitly handled by
+ this macro. Also, the option `-fpcc-struct-return' takes effect
+ regardless of this macro. On most systems, it is possible to
+ leave the macro undefined; this causes a default definition to be
+ used, whose value is the constant 1 for `BLKmode' values, and 0
+ otherwise.
+
+ Do not use this macro to indicate that structures and unions
+ should always be returned in memory. You should instead use
+ `DEFAULT_PCC_STRUCT_RETURN' to indicate this.
+
+`DEFAULT_PCC_STRUCT_RETURN'
+ Define this macro to be 1 if all structure and union return values
+ must be in memory. Since this results in slower code, this should
+ be defined only if needed for compatibility with other compilers
+ or with an ABI. If you define this macro to be 0, then the
+ conventions used for structure and union return values are decided
+ by the `RETURN_IN_MEMORY' macro.
+
+ If not defined, this defaults to the value 1.
+
+`STRUCT_VALUE_REGNUM'
+ If the structure value address is passed in a register, then
+ `STRUCT_VALUE_REGNUM' should be the number of that register.
+
+`STRUCT_VALUE'
+ If the structure value address is not passed in a register, define
+ `STRUCT_VALUE' as an expression returning an RTX for the place
+ where the address is passed. If it returns 0, the address is
+ passed as an "invisible" first argument.
+
+`STRUCT_VALUE_INCOMING_REGNUM'
+ On some architectures the place where the structure value address
+ is found by the called function is not the same place that the
+ caller put it. This can be due to register windows, or it could
+ be because the function prologue moves it to a different place.
+
+ If the incoming location of the structure value address is in a
+ register, define this macro as the register number.
+
+`STRUCT_VALUE_INCOMING'
+ If the incoming location is not a register, then you should define
+ `STRUCT_VALUE_INCOMING' as an expression for an RTX for where the
+ called function should find the value. If it should find the
+ value on the stack, define this to create a `mem' which refers to
+ the frame pointer. A definition of 0 means that the address is
+ passed as an "invisible" first argument.
+
+`PCC_STATIC_STRUCT_RETURN'
+ Define this macro if the usual system convention on the target
+ machine for returning structures and unions is for the called
+ function to return the address of a static variable containing the
+ value.
+
+ Do not define this if the usual system convention is for the
+ caller to pass an address to the subroutine.
+
+ This macro has effect in `-fpcc-struct-return' mode, but it does
+ nothing when you use `-freg-struct-return' mode.
+
+\1f
+File: gccint.info, Node: Caller Saves, Next: Function Entry, Prev: Aggregate Return, Up: Stack and Calling
+
+10.10.10 Caller-Saves Register Allocation
+-----------------------------------------
+
+If you enable it, GCC can save registers around function calls. This
+makes it possible to use call-clobbered registers to hold variables that
+must live across calls.
+
+`DEFAULT_CALLER_SAVES'
+ Define this macro if function calls on the target machine do not
+ preserve any registers; in other words, if `CALL_USED_REGISTERS'
+ has 1 for all registers. When defined, this macro enables
+ `-fcaller-saves' by default for all optimization levels. It has
+ no effect for optimization levels 2 and higher, where
+ `-fcaller-saves' is the default.
+
+`CALLER_SAVE_PROFITABLE (REFS, CALLS)'
+ A C expression to determine whether it is worthwhile to consider
+ placing a pseudo-register in a call-clobbered hard register and
+ saving and restoring it around each function call. The expression
+ should be 1 when this is worth doing, and 0 otherwise.
+
+ If you don't define this macro, a default is used which is good on
+ most machines: `4 * CALLS < REFS'.
+
+`HARD_REGNO_CALLER_SAVE_MODE (REGNO, NREGS)'
+ A C expression specifying which mode is required for saving NREGS
+ of a pseudo-register in call-clobbered hard register REGNO. If
+ REGNO is unsuitable for caller save, `VOIDmode' should be
+ returned. For most machines this macro need not be defined since
+ GCC will select the smallest suitable mode.
+
+\1f
+File: gccint.info, Node: Function Entry, Next: Profiling, Prev: Caller Saves, Up: Stack and Calling
+
+10.10.11 Function Entry and Exit
+--------------------------------
+
+This section describes the macros that output function entry
+("prologue") and exit ("epilogue") code.
+
+ -- Target Hook: void TARGET_ASM_FUNCTION_PROLOGUE (FILE *FILE,
+ HOST_WIDE_INT SIZE)
+ If defined, a function that outputs the assembler code for entry
+ to a function. The prologue is responsible for setting up the
+ stack frame, initializing the frame pointer register, saving
+ registers that must be saved, and allocating SIZE additional bytes
+ of storage for the local variables. SIZE is an integer. FILE is
+ a stdio stream to which the assembler code should be output.
+
+ The label for the beginning of the function need not be output by
+ this macro. That has already been done when the macro is run.
+
+ To determine which registers to save, the macro can refer to the
+ array `regs_ever_live': element R is nonzero if hard register R is
+ used anywhere within the function. This implies the function
+ prologue should save register R, provided it is not one of the
+ call-used registers. (`TARGET_ASM_FUNCTION_EPILOGUE' must
+ likewise use `regs_ever_live'.)
+
+ On machines that have "register windows", the function entry code
+ does not save on the stack the registers that are in the windows,
+ even if they are supposed to be preserved by function calls;
+ instead it takes appropriate steps to "push" the register stack,
+ if any non-call-used registers are used in the function.
+
+ On machines where functions may or may not have frame-pointers, the
+ function entry code must vary accordingly; it must set up the frame
+ pointer if one is wanted, and not otherwise. To determine whether
+ a frame pointer is in wanted, the macro can refer to the variable
+ `frame_pointer_needed'. The variable's value will be 1 at run
+ time in a function that needs a frame pointer. *Note
+ Elimination::.
+
+ The function entry code is responsible for allocating any stack
+ space required for the function. This stack space consists of the
+ regions listed below. In most cases, these regions are allocated
+ in the order listed, with the last listed region closest to the
+ top of the stack (the lowest address if `STACK_GROWS_DOWNWARD' is
+ defined, and the highest address if it is not defined). You can
+ use a different order for a machine if doing so is more convenient
+ or required for compatibility reasons. Except in cases where
+ required by standard or by a debugger, there is no reason why the
+ stack layout used by GCC need agree with that used by other
+ compilers for a machine.
+
+ -- Target Hook: void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *FILE)
+ If defined, a function that outputs assembler code at the end of a
+ prologue. This should be used when the function prologue is being
+ emitted as RTL, and you have some extra assembler that needs to be
+ emitted. *Note prologue instruction pattern::.
+
+ -- Target Hook: void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *FILE)
+ If defined, a function that outputs assembler code at the start of
+ an epilogue. This should be used when the function epilogue is
+ being emitted as RTL, and you have some extra assembler that needs
+ to be emitted. *Note epilogue instruction pattern::.
+
+ -- Target Hook: void TARGET_ASM_FUNCTION_EPILOGUE (FILE *FILE,
+ HOST_WIDE_INT SIZE)
+ If defined, a function that outputs the assembler code for exit
+ from a function. The epilogue is responsible for restoring the
+ saved registers and stack pointer to their values when the
+ function was called, and returning control to the caller. This
+ macro takes the same arguments as the macro
+ `TARGET_ASM_FUNCTION_PROLOGUE', and the registers to restore are
+ determined from `regs_ever_live' and `CALL_USED_REGISTERS' in the
+ same way.
+
+ On some machines, there is a single instruction that does all the
+ work of returning from the function. On these machines, give that
+ instruction the name `return' and do not define the macro
+ `TARGET_ASM_FUNCTION_EPILOGUE' at all.
+
+ Do not define a pattern named `return' if you want the
+ `TARGET_ASM_FUNCTION_EPILOGUE' to be used. If you want the target
+ switches to control whether return instructions or epilogues are
+ used, define a `return' pattern with a validity condition that
+ tests the target switches appropriately. If the `return'
+ pattern's validity condition is false, epilogues will be used.
+
+ On machines where functions may or may not have frame-pointers, the
+ function exit code must vary accordingly. Sometimes the code for
+ these two cases is completely different. To determine whether a
+ frame pointer is wanted, the macro can refer to the variable
+ `frame_pointer_needed'. The variable's value will be 1 when
+ compiling a function that needs a frame pointer.
+
+ Normally, `TARGET_ASM_FUNCTION_PROLOGUE' and
+ `TARGET_ASM_FUNCTION_EPILOGUE' must treat leaf functions specially.
+ The C variable `current_function_is_leaf' is nonzero for such a
+ function. *Note Leaf Functions::.
+
+ On some machines, some functions pop their arguments on exit while
+ others leave that for the caller to do. For example, the 68020
+ when given `-mrtd' pops arguments in functions that take a fixed
+ number of arguments.
+
+ Your definition of the macro `RETURN_POPS_ARGS' decides which
+ functions pop their own arguments. `TARGET_ASM_FUNCTION_EPILOGUE'
+ needs to know what was decided. The variable that is called
+ `current_function_pops_args' is the number of bytes of its
+ arguments that a function should pop. *Note Scalar Return::.
+
+ * A region of `current_function_pretend_args_size' bytes of
+ uninitialized space just underneath the first argument
+ arriving on the stack. (This may not be at the very start of
+ the allocated stack region if the calling sequence has pushed
+ anything else since pushing the stack arguments. But
+ usually, on such machines, nothing else has been pushed yet,
+ because the function prologue itself does all the pushing.)
+ This region is used on machines where an argument may be
+ passed partly in registers and partly in memory, and, in some
+ cases to support the features in `<varargs.h>' and
+ `<stdarg.h>'.
+
+ * An area of memory used to save certain registers used by the
+ function. The size of this area, which may also include
+ space for such things as the return address and pointers to
+ previous stack frames, is machine-specific and usually
+ depends on which registers have been used in the function.
+ Machines with register windows often do not require a save
+ area.
+
+ * A region of at least SIZE bytes, possibly rounded up to an
+ allocation boundary, to contain the local variables of the
+ function. On some machines, this region and the save area
+ may occur in the opposite order, with the save area closer to
+ the top of the stack.
+
+ * Optionally, when `ACCUMULATE_OUTGOING_ARGS' is defined, a
+ region of `current_function_outgoing_args_size' bytes to be
+ used for outgoing argument lists of the function. *Note
+ Stack Arguments::.
+
+ Normally, it is necessary for the macros
+ `TARGET_ASM_FUNCTION_PROLOGUE' and `TARGET_ASM_FUNCTION_EPILOGUE'
+ to treat leaf functions specially. The C variable
+ `current_function_is_leaf' is nonzero for such a function.
+
+`EXIT_IGNORE_STACK'
+ Define this macro as a C expression that is nonzero if the return
+ instruction or the function epilogue ignores the value of the stack
+ pointer; in other words, if it is safe to delete an instruction to
+ adjust the stack pointer before a return from the function.
+
+ Note that this macro's value is relevant only for functions for
+ which frame pointers are maintained. It is never safe to delete a
+ final stack adjustment in a function that has no frame pointer,
+ and the compiler knows this regardless of `EXIT_IGNORE_STACK'.
+
+`EPILOGUE_USES (REGNO)'
+ Define this macro as a C expression that is nonzero for registers
+ that are used by the epilogue or the `return' pattern. The stack
+ and frame pointer registers are already be assumed to be used as
+ needed.
+
+`EH_USES (REGNO)'
+ Define this macro as a C expression that is nonzero for registers
+ that are used by the exception handling mechanism, and so should
+ be considered live on entry to an exception edge.
+
+`DELAY_SLOTS_FOR_EPILOGUE'
+ Define this macro if the function epilogue contains delay slots to
+ which instructions from the rest of the function can be "moved".
+ The definition should be a C expression whose value is an integer
+ representing the number of delay slots there.
+
+`ELIGIBLE_FOR_EPILOGUE_DELAY (INSN, N)'
+ A C expression that returns 1 if INSN can be placed in delay slot
+ number N of the epilogue.
+
+ The argument N is an integer which identifies the delay slot now
+ being considered (since different slots may have different rules of
+ eligibility). It is never negative and is always less than the
+ number of epilogue delay slots (what `DELAY_SLOTS_FOR_EPILOGUE'
+ returns). If you reject a particular insn for a given delay slot,
+ in principle, it may be reconsidered for a subsequent delay slot.
+ Also, other insns may (at least in principle) be considered for
+ the so far unfilled delay slot.
+
+ The insns accepted to fill the epilogue delay slots are put in an
+ RTL list made with `insn_list' objects, stored in the variable
+ `current_function_epilogue_delay_list'. The insn for the first
+ delay slot comes first in the list. Your definition of the macro
+ `TARGET_ASM_FUNCTION_EPILOGUE' should fill the delay slots by
+ outputting the insns in this list, usually by calling
+ `final_scan_insn'.
+
+ You need not define this macro if you did not define
+ `DELAY_SLOTS_FOR_EPILOGUE'.
+
+`ASM_OUTPUT_MI_THUNK (FILE, THUNK_FNDECL, DELTA, FUNCTION)'
+ A C compound statement that outputs the assembler code for a thunk
+ function, used to implement C++ virtual function calls with
+ multiple inheritance. The thunk acts as a wrapper around a
+ virtual function, adjusting the implicit object parameter before
+ handing control off to the real function.
+
+ First, emit code to add the integer DELTA to the location that
+ contains the incoming first argument. Assume that this argument
+ contains a pointer, and is the one used to pass the `this' pointer
+ in C++. This is the incoming argument _before_ the function
+ prologue, e.g. `%o0' on a sparc. The addition must preserve the
+ values of all other incoming arguments.
+
+ After the addition, emit code to jump to FUNCTION, which is a
+ `FUNCTION_DECL'. This is a direct pure jump, not a call, and does
+ not touch the return address. Hence returning from FUNCTION will
+ return to whoever called the current `thunk'.
+
+ The effect must be as if FUNCTION had been called directly with
+ the adjusted first argument. This macro is responsible for
+ emitting all of the code for a thunk function;
+ `TARGET_ASM_FUNCTION_PROLOGUE' and `TARGET_ASM_FUNCTION_EPILOGUE'
+ are not invoked.
+
+ The THUNK_FNDECL is redundant. (DELTA and FUNCTION have already
+ been extracted from it.) It might possibly be useful on some
+ targets, but probably not.
+
+ If you do not define this macro, the target-independent code in
+ the C++ front end will generate a less efficient heavyweight thunk
+ that calls FUNCTION instead of jumping to it. The generic
+ approach does not support varargs.
+
+\1f
+File: gccint.info, Node: Profiling, Next: Tail Calls, Prev: Function Entry, Up: Stack and Calling
+
+10.10.12 Generating Code for Profiling
+--------------------------------------
+
+These macros will help you generate code for profiling.
+
+`FUNCTION_PROFILER (FILE, LABELNO)'
+ A C statement or compound statement to output to FILE some
+ assembler code to call the profiling subroutine `mcount'.
+
+ The details of how `mcount' expects to be called are determined by
+ your operating system environment, not by GCC. To figure them out,
+ compile a small program for profiling using the system's installed
+ C compiler and look at the assembler code that results.
+
+ Older implementations of `mcount' expect the address of a counter
+ variable to be loaded into some register. The name of this
+ variable is `LP' followed by the number LABELNO, so you would
+ generate the name using `LP%d' in a `fprintf'.
+
+`PROFILE_HOOK'
+ A C statement or compound statement to output to FILE some assembly
+ code to call the profiling subroutine `mcount' even the target does
+ not support profiling.
+
+`NO_PROFILE_COUNTERS'
+ Define this macro if the `mcount' subroutine on your system does
+ not need a counter variable allocated for each function. This is
+ true for almost all modern implementations. If you define this
+ macro, you must not use the LABELNO argument to
+ `FUNCTION_PROFILER'.
+
+`PROFILE_BEFORE_PROLOGUE'
+ Define this macro if the code for function profiling should come
+ before the function prologue. Normally, the profiling code comes
+ after.
+
+`TARGET_ALLOWS_PROFILING_WITHOUT_FRAME_POINTER'
+ On some targets, it is impossible to use profiling when the frame
+ pointer has been omitted. For example, on x86 GNU/Linux systems,
+ the `mcount' routine provided by the GNU C Library finds the
+ address of the routine that called the routine that called `mcount'
+ by looking in the immediate caller's stack frame. If the immediate
+ caller has no frame pointer, this lookup will fail.
+
+ By default, GCC assumes that the target does allow profiling when
+ the frame pointer is omitted. This macro should be defined to a C
+ expression that evaluates to `false' if the target does not allow
+ profiling when the frame pointer is omitted.
+
+
+\1f
+File: gccint.info, Node: Tail Calls, Prev: Profiling, Up: Stack and Calling
+
+10.10.13 Permitting tail calls
+------------------------------
+
+`FUNCTION_OK_FOR_SIBCALL (DECL)'
+ A C expression that evaluates to true if it is ok to perform a
+ sibling call to DECL from the current function.
+
+ It is not uncommon for limitations of calling conventions to
+ prevent tail calls to functions outside the current unit of
+ translation, or during PIC compilation. Use this macro to enforce
+ these restrictions, as the `sibcall' md pattern can not fail, or
+ fall over to a "normal" call.
+
+\1f
+File: gccint.info, Node: Varargs, Next: Trampolines, Prev: Stack and Calling, Up: Target Macros
+
+10.11 Implementing the Varargs Macros
+=====================================
+
+GCC comes with an implementation of `<varargs.h>' and `<stdarg.h>' that
+work without change on machines that pass arguments on the stack.
+Other machines require their own implementations of varargs, and the
+two machine independent header files must have conditionals to include
+it.
+
+ ISO `<stdarg.h>' differs from traditional `<varargs.h>' mainly in
+the calling convention for `va_start'. The traditional implementation
+takes just one argument, which is the variable in which to store the
+argument pointer. The ISO implementation of `va_start' takes an
+additional second argument. The user is supposed to write the last
+named argument of the function here.
+
+ However, `va_start' should not use this argument. The way to find
+the end of the named arguments is with the built-in functions described
+below.
+
+`__builtin_saveregs ()'
+ Use this built-in function to save the argument registers in
+ memory so that the varargs mechanism can access them. Both ISO
+ and traditional versions of `va_start' must use
+ `__builtin_saveregs', unless you use `SETUP_INCOMING_VARARGS' (see
+ below) instead.
+
+ On some machines, `__builtin_saveregs' is open-coded under the
+ control of the macro `EXPAND_BUILTIN_SAVEREGS'. On other machines,
+ it calls a routine written in assembler language, found in
+ `libgcc2.c'.
+
+ Code generated for the call to `__builtin_saveregs' appears at the
+ beginning of the function, as opposed to where the call to
+ `__builtin_saveregs' is written, regardless of what the code is.
+ This is because the registers must be saved before the function
+ starts to use them for its own purposes.
+
+`__builtin_args_info (CATEGORY)'
+ Use this built-in function to find the first anonymous arguments in
+ registers.
+
+ In general, a machine may have several categories of registers
+ used for arguments, each for a particular category of data types.
+ (For example, on some machines, floating-point registers are used
+ for floating-point arguments while other arguments are passed in
+ the general registers.) To make non-varargs functions use the
+ proper calling convention, you have defined the `CUMULATIVE_ARGS'
+ data type to record how many registers in each category have been
+ used so far
+
+ `__builtin_args_info' accesses the same data structure of type
+ `CUMULATIVE_ARGS' after the ordinary argument layout is finished
+ with it, with CATEGORY specifying which word to access. Thus, the
+ value indicates the first unused register in a given category.
+
+ Normally, you would use `__builtin_args_info' in the implementation
+ of `va_start', accessing each category just once and storing the
+ value in the `va_list' object. This is because `va_list' will
+ have to update the values, and there is no way to alter the values
+ accessed by `__builtin_args_info'.
+
+`__builtin_next_arg (LASTARG)'
+ This is the equivalent of `__builtin_args_info', for stack
+ arguments. It returns the address of the first anonymous stack
+ argument, as type `void *'. If `ARGS_GROW_DOWNWARD', it returns
+ the address of the location above the first anonymous stack
+ argument. Use it in `va_start' to initialize the pointer for
+ fetching arguments from the stack. Also use it in `va_start' to
+ verify that the second parameter LASTARG is the last named argument
+ of the current function.
+
+`__builtin_classify_type (OBJECT)'
+ Since each machine has its own conventions for which data types are
+ passed in which kind of register, your implementation of `va_arg'
+ has to embody these conventions. The easiest way to categorize the
+ specified data type is to use `__builtin_classify_type' together
+ with `sizeof' and `__alignof__'.
+
+ `__builtin_classify_type' ignores the value of OBJECT, considering
+ only its data type. It returns an integer describing what kind of
+ type that is--integer, floating, pointer, structure, and so on.
+
+ The file `typeclass.h' defines an enumeration that you can use to
+ interpret the values of `__builtin_classify_type'.
+
+ These machine description macros help implement varargs:
+
+`EXPAND_BUILTIN_SAVEREGS ()'
+ If defined, is a C expression that produces the machine-specific
+ code for a call to `__builtin_saveregs'. This code will be moved
+ to the very beginning of the function, before any parameter access
+ are made. The return value of this function should be an RTX that
+ contains the value to use as the return of `__builtin_saveregs'.
+
+`SETUP_INCOMING_VARARGS (ARGS_SO_FAR, MODE, TYPE, PRETEND_ARGS_SIZE, SECOND_TIME)'
+ This macro offers an alternative to using `__builtin_saveregs' and
+ defining the macro `EXPAND_BUILTIN_SAVEREGS'. Use it to store the
+ anonymous register arguments into the stack so that all the
+ arguments appear to have been passed consecutively on the stack.
+ Once this is done, you can use the standard implementation of
+ varargs that works for machines that pass all their arguments on
+ the stack.
+
+ The argument ARGS_SO_FAR is the `CUMULATIVE_ARGS' data structure,
+ containing the values that are obtained after processing the named
+ arguments. The arguments MODE and TYPE describe the last named
+ argument--its machine mode and its data type as a tree node.
+
+ The macro implementation should do two things: first, push onto the
+ stack all the argument registers _not_ used for the named
+ arguments, and second, store the size of the data thus pushed into
+ the `int'-valued variable whose name is supplied as the argument
+ PRETEND_ARGS_SIZE. The value that you store here will serve as
+ additional offset for setting up the stack frame.
+
+ Because you must generate code to push the anonymous arguments at
+ compile time without knowing their data types,
+ `SETUP_INCOMING_VARARGS' is only useful on machines that have just
+ a single category of argument register and use it uniformly for
+ all data types.
+
+ If the argument SECOND_TIME is nonzero, it means that the
+ arguments of the function are being analyzed for the second time.
+ This happens for an inline function, which is not actually
+ compiled until the end of the source file. The macro
+ `SETUP_INCOMING_VARARGS' should not generate any instructions in
+ this case.
+
+`STRICT_ARGUMENT_NAMING'
+ Define this macro to be a nonzero value if the location where a
+ function argument is passed depends on whether or not it is a
+ named argument.
+
+ This macro controls how the NAMED argument to `FUNCTION_ARG' is
+ set for varargs and stdarg functions. If this macro returns a
+ nonzero value, the NAMED argument is always true for named
+ arguments, and false for unnamed arguments. If it returns a value
+ of zero, but `SETUP_INCOMING_VARARGS' is defined, then all
+ arguments are treated as named. Otherwise, all named arguments
+ except the last are treated as named.
+
+ You need not define this macro if it always returns zero.
+
+`PRETEND_OUTGOING_VARARGS_NAMED'
+ If you need to conditionally change ABIs so that one works with
+ `SETUP_INCOMING_VARARGS', but the other works like neither
+ `SETUP_INCOMING_VARARGS' nor `STRICT_ARGUMENT_NAMING' was defined,
+ then define this macro to return nonzero if
+ `SETUP_INCOMING_VARARGS' is used, zero otherwise. Otherwise, you
+ should not define this macro.
+
+\1f
+File: gccint.info, Node: Trampolines, Next: Library Calls, Prev: Varargs, Up: Target Macros
+
+10.12 Trampolines for Nested Functions
+======================================
+
+A "trampoline" is a small piece of code that is created at run time
+when the address of a nested function is taken. It normally resides on
+the stack, in the stack frame of the containing function. These macros
+tell GCC how to generate code to allocate and initialize a trampoline.
+
+ The instructions in the trampoline must do two things: load a
+constant address into the static chain register, and jump to the real
+address of the nested function. On CISC machines such as the m68k,
+this requires two instructions, a move immediate and a jump. Then the
+two addresses exist in the trampoline as word-long immediate operands.
+On RISC machines, it is often necessary to load each address into a
+register in two parts. Then pieces of each address form separate
+immediate operands.
+
+ The code generated to initialize the trampoline must store the
+variable parts--the static chain value and the function address--into
+the immediate operands of the instructions. On a CISC machine, this is
+simply a matter of copying each address to a memory reference at the
+proper offset from the start of the trampoline. On a RISC machine, it
+may be necessary to take out pieces of the address and store them
+separately.
+
+`TRAMPOLINE_TEMPLATE (FILE)'
+ A C statement to output, on the stream FILE, assembler code for a
+ block of data that contains the constant parts of a trampoline.
+ This code should not include a label--the label is taken care of
+ automatically.
+
+ If you do not define this macro, it means no template is needed
+ for the target. Do not define this macro on systems where the
+ block move code to copy the trampoline into place would be larger
+ than the code to generate it on the spot.
+
+`TRAMPOLINE_SECTION'
+ The name of a subroutine to switch to the section in which the
+ trampoline template is to be placed (*note Sections::). The
+ default is a value of `readonly_data_section', which places the
+ trampoline in the section containing read-only data.
+
+`TRAMPOLINE_SIZE'
+ A C expression for the size in bytes of the trampoline, as an
+ integer.
+
+`TRAMPOLINE_ALIGNMENT'
+ Alignment required for trampolines, in bits.
+
+ If you don't define this macro, the value of `BIGGEST_ALIGNMENT'
+ is used for aligning trampolines.
+
+`INITIALIZE_TRAMPOLINE (ADDR, FNADDR, STATIC_CHAIN)'
+ A C statement to initialize the variable parts of a trampoline.
+ ADDR is an RTX for the address of the trampoline; FNADDR is an RTX
+ for the address of the nested function; STATIC_CHAIN is an RTX for
+ the static chain value that should be passed to the function when
+ it is called.
+
+`TRAMPOLINE_ADJUST_ADDRESS (ADDR)'
+ A C statement that should perform any machine-specific adjustment
+ in the address of the trampoline. Its argument contains the
+ address that was passed to `INITIALIZE_TRAMPOLINE'. In case the
+ address to be used for a function call should be different from
+ the address in which the template was stored, the different
+ address should be assigned to ADDR. If this macro is not defined,
+ ADDR will be used for function calls.
+
+`ALLOCATE_TRAMPOLINE (FP)'
+ A C expression to allocate run-time space for a trampoline. The
+ expression value should be an RTX representing a memory reference
+ to the space for the trampoline.
+
+ If this macro is not defined, by default the trampoline is
+ allocated as a stack slot. This default is right for most
+ machines. The exceptions are machines where it is impossible to
+ execute instructions in the stack area. On such machines, you may
+ have to implement a separate stack, using this macro in
+ conjunction with `TARGET_ASM_FUNCTION_PROLOGUE' and
+ `TARGET_ASM_FUNCTION_EPILOGUE'.
+
+ FP points to a data structure, a `struct function', which
+ describes the compilation status of the immediate containing
+ function of the function which the trampoline is for. Normally
+ (when `ALLOCATE_TRAMPOLINE' is not defined), the stack slot for the
+ trampoline is in the stack frame of this containing function.
+ Other allocation strategies probably must do something analogous
+ with this information.
+
+ Implementing trampolines is difficult on many machines because they
+have separate instruction and data caches. Writing into a stack
+location fails to clear the memory in the instruction cache, so when
+the program jumps to that location, it executes the old contents.
+
+ Here are two possible solutions. One is to clear the relevant parts
+of the instruction cache whenever a trampoline is set up. The other is
+to make all trampolines identical, by having them jump to a standard
+subroutine. The former technique makes trampoline execution faster; the
+latter makes initialization faster.
+
+ To clear the instruction cache when a trampoline is initialized,
+define the following macros which describe the shape of the cache.
+
+`INSN_CACHE_SIZE'
+ The total size in bytes of the cache.
+
+`INSN_CACHE_LINE_WIDTH'
+ The length in bytes of each cache line. The cache is divided into
+ cache lines which are disjoint slots, each holding a contiguous
+ chunk of data fetched from memory. Each time data is brought into
+ the cache, an entire line is read at once. The data loaded into a
+ cache line is always aligned on a boundary equal to the line size.
+
+`INSN_CACHE_DEPTH'
+ The number of alternative cache lines that can hold any particular
+ memory location.
+
+ Alternatively, if the machine has system calls or instructions to
+clear the instruction cache directly, you can define the following
+macro.
+
+`CLEAR_INSN_CACHE (BEG, END)'
+ If defined, expands to a C expression clearing the _instruction
+ cache_ in the specified interval. If it is not defined, and the
+ macro `INSN_CACHE_SIZE' is defined, some generic code is generated
+ to clear the cache. The definition of this macro would typically
+ be a series of `asm' statements. Both BEG and END are both pointer
+ expressions.
+
+ To use a standard subroutine, define the following macro. In
+addition, you must make sure that the instructions in a trampoline fill
+an entire cache line with identical instructions, or else ensure that
+the beginning of the trampoline code is always aligned at the same
+point in its cache line. Look in `m68k.h' as a guide.
+
+`TRANSFER_FROM_TRAMPOLINE'
+ Define this macro if trampolines need a special subroutine to do
+ their work. The macro should expand to a series of `asm'
+ statements which will be compiled with GCC. They go in a library
+ function named `__transfer_from_trampoline'.
+
+ If you need to avoid executing the ordinary prologue code of a
+ compiled C function when you jump to the subroutine, you can do so
+ by placing a special label of your own in the assembler code. Use
+ one `asm' statement to generate an assembler label, and another to
+ make the label global. Then trampolines can use that label to
+ jump directly to your special assembler code.
+
+\1f
+File: gccint.info, Node: Library Calls, Next: Addressing Modes, Prev: Trampolines, Up: Target Macros
+
+10.13 Implicit Calls to Library Routines
+========================================
+
+Here is an explanation of implicit calls to library routines.
+
+`MULSI3_LIBCALL'
+ A C string constant giving the name of the function to call for
+ multiplication of one signed full-word by another. If you do not
+ define this macro, the default name is used, which is `__mulsi3',
+ a function defined in `libgcc.a'.
+
+`DIVSI3_LIBCALL'
+ A C string constant giving the name of the function to call for
+ division of one signed full-word by another. If you do not define
+ this macro, the default name is used, which is `__divsi3', a
+ function defined in `libgcc.a'.
+
+`UDIVSI3_LIBCALL'
+ A C string constant giving the name of the function to call for
+ division of one unsigned full-word by another. If you do not
+ define this macro, the default name is used, which is `__udivsi3',
+ a function defined in `libgcc.a'.
+
+`MODSI3_LIBCALL'
+ A C string constant giving the name of the function to call for the
+ remainder in division of one signed full-word by another. If you
+ do not define this macro, the default name is used, which is
+ `__modsi3', a function defined in `libgcc.a'.
+
+`UMODSI3_LIBCALL'
+ A C string constant giving the name of the function to call for the
+ remainder in division of one unsigned full-word by another. If
+ you do not define this macro, the default name is used, which is
+ `__umodsi3', a function defined in `libgcc.a'.
+
+`MULDI3_LIBCALL'
+ A C string constant giving the name of the function to call for
+ multiplication of one signed double-word by another. If you do not
+ define this macro, the default name is used, which is `__muldi3',
+ a function defined in `libgcc.a'.
+
+`DIVDI3_LIBCALL'
+ A C string constant giving the name of the function to call for
+ division of one signed double-word by another. If you do not
+ define this macro, the default name is used, which is `__divdi3', a
+ function defined in `libgcc.a'.
+
+`UDIVDI3_LIBCALL'
+ A C string constant giving the name of the function to call for
+ division of one unsigned full-word by another. If you do not
+ define this macro, the default name is used, which is `__udivdi3',
+ a function defined in `libgcc.a'.
+
+`MODDI3_LIBCALL'
+ A C string constant giving the name of the function to call for the
+ remainder in division of one signed double-word by another. If
+ you do not define this macro, the default name is used, which is
+ `__moddi3', a function defined in `libgcc.a'.
+
+`UMODDI3_LIBCALL'
+ A C string constant giving the name of the function to call for the
+ remainder in division of one unsigned full-word by another. If
+ you do not define this macro, the default name is used, which is
+ `__umoddi3', a function defined in `libgcc.a'.
+
+`INIT_TARGET_OPTABS'
+ Define this macro as a C statement that declares additional library
+ routines renames existing ones. `init_optabs' calls this macro
+ after initializing all the normal library routines.
+
+`FLOAT_LIB_COMPARE_RETURNS_BOOL'
+ Define this macro as a C statement that returns nonzero if a call
+ to the floating point comparison library function will return a
+ boolean value that indicates the result of the comparison. It
+ should return zero if one of gcc's own libgcc functions is called.
+
+ Most ports don't need to define this macro.
+
+`TARGET_EDOM'
+ The value of `EDOM' on the target machine, as a C integer constant
+ expression. If you don't define this macro, GCC does not attempt
+ to deposit the value of `EDOM' into `errno' directly. Look in
+ `/usr/include/errno.h' to find the value of `EDOM' on your system.
+
+ If you do not define `TARGET_EDOM', then compiled code reports
+ domain errors by calling the library function and letting it
+ report the error. If mathematical functions on your system use
+ `matherr' when there is an error, then you should leave
+ `TARGET_EDOM' undefined so that `matherr' is used normally.
+
+`GEN_ERRNO_RTX'
+ Define this macro as a C expression to create an rtl expression
+ that refers to the global "variable" `errno'. (On certain systems,
+ `errno' may not actually be a variable.) If you don't define this
+ macro, a reasonable default is used.
+
+`TARGET_MEM_FUNCTIONS'
+ Define this macro if GCC should generate calls to the ISO C (and
+ System V) library functions `memcpy', `memmove' and `memset'
+ rather than the BSD functions `bcopy' and `bzero'.
+
+`LIBGCC_NEEDS_DOUBLE'
+ Define this macro if `float' arguments cannot be passed to library
+ routines (so they must be converted to `double'). This macro
+ affects both how library calls are generated and how the library
+ routines in `libgcc.a' accept their arguments. It is useful on
+ machines where floating and fixed point arguments are passed
+ differently, such as the i860.
+
+`NEXT_OBJC_RUNTIME'
+ Define this macro to generate code for Objective-C message sending
+ using the calling convention of the NeXT system. This calling
+ convention involves passing the object, the selector and the
+ method arguments all at once to the method-lookup library function.
+
+ The default calling convention passes just the object and the
+ selector to the lookup function, which returns a pointer to the
+ method.
+
+\1f
+File: gccint.info, Node: Addressing Modes, Next: Condition Code, Prev: Library Calls, Up: Target Macros
+
+10.14 Addressing Modes
+======================
+
+This is about addressing modes.
+
+`HAVE_PRE_INCREMENT'
+`HAVE_PRE_DECREMENT'
+`HAVE_POST_INCREMENT'
+`HAVE_POST_DECREMENT'
+ A C expression that is nonzero if the machine supports
+ pre-increment, pre-decrement, post-increment, or post-decrement
+ addressing respectively.
+
+`HAVE_PRE_MODIFY_DISP'
+`HAVE_POST_MODIFY_DISP'
+ A C expression that is nonzero if the machine supports pre- or
+ post-address side-effect generation involving constants other than
+ the size of the memory operand.
+
+`HAVE_PRE_MODIFY_REG'
+`HAVE_POST_MODIFY_REG'
+ A C expression that is nonzero if the machine supports pre- or
+ post-address side-effect generation involving a register
+ displacement.
+
+`CONSTANT_ADDRESS_P (X)'
+ A C expression that is 1 if the RTX X is a constant which is a
+ valid address. On most machines, this can be defined as
+ `CONSTANT_P (X)', but a few machines are more restrictive in which
+ constant addresses are supported.
+
+ `CONSTANT_P' accepts integer-values expressions whose values are
+ not explicitly known, such as `symbol_ref', `label_ref', and
+ `high' expressions and `const' arithmetic expressions, in addition
+ to `const_int' and `const_double' expressions.
+
+`MAX_REGS_PER_ADDRESS'
+ A number, the maximum number of registers that can appear in a
+ valid memory address. Note that it is up to you to specify a
+ value equal to the maximum number that `GO_IF_LEGITIMATE_ADDRESS'
+ would ever accept.
+
+`GO_IF_LEGITIMATE_ADDRESS (MODE, X, LABEL)'
+ A C compound statement with a conditional `goto LABEL;' executed
+ if X (an RTX) is a legitimate memory address on the target machine
+ for a memory operand of mode MODE.
+
+ It usually pays to define several simpler macros to serve as
+ subroutines for this one. Otherwise it may be too complicated to
+ understand.
+
+ This macro must exist in two variants: a strict variant and a
+ non-strict one. The strict variant is used in the reload pass. It
+ must be defined so that any pseudo-register that has not been
+ allocated a hard register is considered a memory reference. In
+ contexts where some kind of register is required, a pseudo-register
+ with no hard register must be rejected.
+
+ The non-strict variant is used in other passes. It must be
+ defined to accept all pseudo-registers in every context where some
+ kind of register is required.
+
+ Compiler source files that want to use the strict variant of this
+ macro define the macro `REG_OK_STRICT'. You should use an `#ifdef
+ REG_OK_STRICT' conditional to define the strict variant in that
+ case and the non-strict variant otherwise.
+
+ Subroutines to check for acceptable registers for various purposes
+ (one for base registers, one for index registers, and so on) are
+ typically among the subroutines used to define
+ `GO_IF_LEGITIMATE_ADDRESS'. Then only these subroutine macros
+ need have two variants; the higher levels of macros may be the
+ same whether strict or not.
+
+ Normally, constant addresses which are the sum of a `symbol_ref'
+ and an integer are stored inside a `const' RTX to mark them as
+ constant. Therefore, there is no need to recognize such sums
+ specifically as legitimate addresses. Normally you would simply
+ recognize any `const' as legitimate.
+
+ Usually `PRINT_OPERAND_ADDRESS' is not prepared to handle constant
+ sums that are not marked with `const'. It assumes that a naked
+ `plus' indicates indexing. If so, then you _must_ reject such
+ naked constant sums as illegitimate addresses, so that none of
+ them will be given to `PRINT_OPERAND_ADDRESS'.
+
+ On some machines, whether a symbolic address is legitimate depends
+ on the section that the address refers to. On these machines,
+ define the macro `ENCODE_SECTION_INFO' to store the information
+ into the `symbol_ref', and then check for it here. When you see a
+ `const', you will have to look inside it to find the `symbol_ref'
+ in order to determine the section. *Note Assembler Format::.
+
+ The best way to modify the name string is by adding text to the
+ beginning, with suitable punctuation to prevent any ambiguity.
+ Allocate the new name in `saveable_obstack'. You will have to
+ modify `ASM_OUTPUT_LABELREF' to remove and decode the added text
+ and output the name accordingly, and define `STRIP_NAME_ENCODING'
+ to access the original name string.
+
+ You can check the information stored here into the `symbol_ref' in
+ the definitions of the macros `GO_IF_LEGITIMATE_ADDRESS' and
+ `PRINT_OPERAND_ADDRESS'.
+
+`REG_OK_FOR_BASE_P (X)'
+ A C expression that is nonzero if X (assumed to be a `reg' RTX) is
+ valid for use as a base register. For hard registers, it should
+ always accept those which the hardware permits and reject the
+ others. Whether the macro accepts or rejects pseudo registers
+ must be controlled by `REG_OK_STRICT' as described above. This
+ usually requires two variant definitions, of which `REG_OK_STRICT'
+ controls the one actually used.
+
+`REG_MODE_OK_FOR_BASE_P (X, MODE)'
+ A C expression that is just like `REG_OK_FOR_BASE_P', except that
+ that expression may examine the mode of the memory reference in
+ MODE. You should define this macro if the mode of the memory
+ reference affects whether a register may be used as a base
+ register. If you define this macro, the compiler will use it
+ instead of `REG_OK_FOR_BASE_P'.
+
+`REG_OK_FOR_INDEX_P (X)'
+ A C expression that is nonzero if X (assumed to be a `reg' RTX) is
+ valid for use as an index register.
+
+ The difference between an index register and a base register is
+ that the index register may be scaled. If an address involves the
+ sum of two registers, neither one of them scaled, then either one
+ may be labeled the "base" and the other the "index"; but whichever
+ labeling is used must fit the machine's constraints of which
+ registers may serve in each capacity. The compiler will try both
+ labelings, looking for one that is valid, and will reload one or
+ both registers only if neither labeling works.
+
+`FIND_BASE_TERM (X)'
+ A C expression to determine the base term of address X. This
+ macro is used in only one place: `find_base_term' in alias.c.
+
+ It is always safe for this macro to not be defined. It exists so
+ that alias analysis can understand machine-dependent addresses.
+
+ The typical use of this macro is to handle addresses containing a
+ label_ref or symbol_ref within an UNSPEC.
+
+`LEGITIMIZE_ADDRESS (X, OLDX, MODE, WIN)'
+ A C compound statement that attempts to replace X with a valid
+ memory address for an operand of mode MODE. WIN will be a C
+ statement label elsewhere in the code; the macro definition may use
+
+ GO_IF_LEGITIMATE_ADDRESS (MODE, X, WIN);
+
+ to avoid further processing if the address has become legitimate.
+
+ X will always be the result of a call to `break_out_memory_refs',
+ and OLDX will be the operand that was given to that function to
+ produce X.
+
+ The code generated by this macro should not alter the substructure
+ of X. If it transforms X into a more legitimate form, it should
+ assign X (which will always be a C variable) a new value.
+
+ It is not necessary for this macro to come up with a legitimate
+ address. The compiler has standard ways of doing so in all cases.
+ In fact, it is safe for this macro to do nothing. But often a
+ machine-dependent strategy can generate better code.
+
+`LEGITIMIZE_RELOAD_ADDRESS (X, MODE, OPNUM, TYPE, IND_LEVELS, WIN)'
+ A C compound statement that attempts to replace X, which is an
+ address that needs reloading, with a valid memory address for an
+ operand of mode MODE. WIN will be a C statement label elsewhere
+ in the code. It is not necessary to define this macro, but it
+ might be useful for performance reasons.
+
+ For example, on the i386, it is sometimes possible to use a single
+ reload register instead of two by reloading a sum of two pseudo
+ registers into a register. On the other hand, for number of RISC
+ processors offsets are limited so that often an intermediate
+ address needs to be generated in order to address a stack slot.
+ By defining `LEGITIMIZE_RELOAD_ADDRESS' appropriately, the
+ intermediate addresses generated for adjacent some stack slots can
+ be made identical, and thus be shared.
+
+ _Note_: This macro should be used with caution. It is necessary
+ to know something of how reload works in order to effectively use
+ this, and it is quite easy to produce macros that build in too
+ much knowledge of reload internals.
+
+ _Note_: This macro must be able to reload an address created by a
+ previous invocation of this macro. If it fails to handle such
+ addresses then the compiler may generate incorrect code or abort.
+
+ The macro definition should use `push_reload' to indicate parts
+ that need reloading; OPNUM, TYPE and IND_LEVELS are usually
+ suitable to be passed unaltered to `push_reload'.
+
+ The code generated by this macro must not alter the substructure of
+ X. If it transforms X into a more legitimate form, it should
+ assign X (which will always be a C variable) a new value. This
+ also applies to parts that you change indirectly by calling
+ `push_reload'.
+
+ The macro definition may use `strict_memory_address_p' to test if
+ the address has become legitimate.
+
+ If you want to change only a part of X, one standard way of doing
+ this is to use `copy_rtx'. Note, however, that is unshares only a
+ single level of rtl. Thus, if the part to be changed is not at the
+ top level, you'll need to replace first the top level. It is not
+ necessary for this macro to come up with a legitimate address;
+ but often a machine-dependent strategy can generate better code.
+
+`GO_IF_MODE_DEPENDENT_ADDRESS (ADDR, LABEL)'
+ A C statement or compound statement with a conditional `goto
+ LABEL;' executed if memory address X (an RTX) can have different
+ meanings depending on the machine mode of the memory reference it
+ is used for or if the address is valid for some modes but not
+ others.
+
+ Autoincrement and autodecrement addresses typically have
+ mode-dependent effects because the amount of the increment or
+ decrement is the size of the operand being addressed. Some
+ machines have other mode-dependent addresses. Many RISC machines
+ have no mode-dependent addresses.
+
+ You may assume that ADDR is a valid address for the machine.
+
+`LEGITIMATE_CONSTANT_P (X)'
+ A C expression that is nonzero if X is a legitimate constant for
+ an immediate operand on the target machine. You can assume that X
+ satisfies `CONSTANT_P', so you need not check this. In fact, `1'
+ is a suitable definition for this macro on machines where anything
+ `CONSTANT_P' is valid.
+
+\1f
+File: gccint.info, Node: Condition Code, Next: Costs, Prev: Addressing Modes, Up: Target Macros
+
+10.15 Condition Code Status
+===========================
+
+This describes the condition code status.
+
+ The file `conditions.h' defines a variable `cc_status' to describe
+how the condition code was computed (in case the interpretation of the
+condition code depends on the instruction that it was set by). This
+variable contains the RTL expressions on which the condition code is
+currently based, and several standard flags.
+
+ Sometimes additional machine-specific flags must be defined in the
+machine description header file. It can also add additional
+machine-specific information by defining `CC_STATUS_MDEP'.
+
+`CC_STATUS_MDEP'
+ C code for a data type which is used for declaring the `mdep'
+ component of `cc_status'. It defaults to `int'.
+
+ This macro is not used on machines that do not use `cc0'.
+
+`CC_STATUS_MDEP_INIT'
+ A C expression to initialize the `mdep' field to "empty". The
+ default definition does nothing, since most machines don't use the
+ field anyway. If you want to use the field, you should probably
+ define this macro to initialize it.
+
+ This macro is not used on machines that do not use `cc0'.
+
+`NOTICE_UPDATE_CC (EXP, INSN)'
+ A C compound statement to set the components of `cc_status'
+ appropriately for an insn INSN whose body is EXP. It is this
+ macro's responsibility to recognize insns that set the condition
+ code as a byproduct of other activity as well as those that
+ explicitly set `(cc0)'.
+
+ This macro is not used on machines that do not use `cc0'.
+
+ If there are insns that do not set the condition code but do alter
+ other machine registers, this macro must check to see whether they
+ invalidate the expressions that the condition code is recorded as
+ reflecting. For example, on the 68000, insns that store in address
+ registers do not set the condition code, which means that usually
+ `NOTICE_UPDATE_CC' can leave `cc_status' unaltered for such insns.
+ But suppose that the previous insn set the condition code based on
+ location `a4@(102)' and the current insn stores a new value in
+ `a4'. Although the condition code is not changed by this, it will
+ no longer be true that it reflects the contents of `a4@(102)'.
+ Therefore, `NOTICE_UPDATE_CC' must alter `cc_status' in this case
+ to say that nothing is known about the condition code value.
+
+ The definition of `NOTICE_UPDATE_CC' must be prepared to deal with
+ the results of peephole optimization: insns whose patterns are
+ `parallel' RTXs containing various `reg', `mem' or constants which
+ are just the operands. The RTL structure of these insns is not
+ sufficient to indicate what the insns actually do. What
+ `NOTICE_UPDATE_CC' should do when it sees one is just to run
+ `CC_STATUS_INIT'.
+
+ A possible definition of `NOTICE_UPDATE_CC' is to call a function
+ that looks at an attribute (*note Insn Attributes::) named, for
+ example, `cc'. This avoids having detailed information about
+ patterns in two places, the `md' file and in `NOTICE_UPDATE_CC'.
+
+`EXTRA_CC_MODES'
+ A list of additional modes for condition code values in registers
+ (*note Jump Patterns::). This macro should expand to a sequence of
+ calls of the macro `CC' separated by white space. `CC' takes two
+ arguments. The first is the enumeration name of the mode, which
+ should begin with `CC' and end with `mode'. The second is a C
+ string giving the printable name of the mode; it should be the
+ same as the first argument, but with the trailing `mode' removed.
+
+ You should only define this macro if additional modes are required.
+
+ A sample definition of `EXTRA_CC_MODES' is:
+ #define EXTRA_CC_MODES \
+ CC(CC_NOOVmode, "CC_NOOV") \
+ CC(CCFPmode, "CCFP") \
+ CC(CCFPEmode, "CCFPE")
+
+`SELECT_CC_MODE (OP, X, Y)'
+ Returns a mode from class `MODE_CC' to be used when comparison
+ operation code OP is applied to rtx X and Y. For example, on the
+ Sparc, `SELECT_CC_MODE' is defined as (see *note Jump Patterns::
+ for a description of the reason for this definition)
+
+ #define SELECT_CC_MODE(OP,X,Y) \
+ (GET_MODE_CLASS (GET_MODE (X)) == MODE_FLOAT \
+ ? ((OP == EQ || OP == NE) ? CCFPmode : CCFPEmode) \
+ : ((GET_CODE (X) == PLUS || GET_CODE (X) == MINUS \
+ || GET_CODE (X) == NEG) \
+ ? CC_NOOVmode : CCmode))
+
+ You need not define this macro if `EXTRA_CC_MODES' is not defined.
+
+`CANONICALIZE_COMPARISON (CODE, OP0, OP1)'
+ On some machines not all possible comparisons are defined, but you
+ can convert an invalid comparison into a valid one. For example,
+ the Alpha does not have a `GT' comparison, but you can use an `LT'
+ comparison instead and swap the order of the operands.
+
+ On such machines, define this macro to be a C statement to do any
+ required conversions. CODE is the initial comparison code and OP0
+ and OP1 are the left and right operands of the comparison,
+ respectively. You should modify CODE, OP0, and OP1 as required.
+
+ GCC will not assume that the comparison resulting from this macro
+ is valid but will see if the resulting insn matches a pattern in
+ the `md' file.
+
+ You need not define this macro if it would never change the
+ comparison code or operands.
+
+`REVERSIBLE_CC_MODE (MODE)'
+ A C expression whose value is one if it is always safe to reverse a
+ comparison whose mode is MODE. If `SELECT_CC_MODE' can ever
+ return MODE for a floating-point inequality comparison, then
+ `REVERSIBLE_CC_MODE (MODE)' must be zero.
+
+ You need not define this macro if it would always returns zero or
+ if the floating-point format is anything other than
+ `IEEE_FLOAT_FORMAT'. For example, here is the definition used on
+ the Sparc, where floating-point inequality comparisons are always
+ given `CCFPEmode':
+
+ #define REVERSIBLE_CC_MODE(MODE) ((MODE) != CCFPEmode)
+
+ A C expression whose value is reversed condition code of the CODE
+ for comparison done in CC_MODE MODE. The macro is used only in
+ case `REVERSIBLE_CC_MODE (MODE)' is nonzero. Define this macro in
+ case machine has some non-standard way how to reverse certain
+ conditionals. For instance in case all floating point conditions
+ are non-trapping, compiler may freely convert unordered compares
+ to ordered one. Then definition may look like:
+
+ #define REVERSE_CONDITION(CODE, MODE) \
+ ((MODE) != CCFPmode ? reverse_condition (CODE) \
+ : reverse_condition_maybe_unordered (CODE))
+
+`REVERSE_CONDEXEC_PREDICATES_P (CODE1, CODE2)'
+ A C expression that returns true if the conditional execution
+ predicate CODE1 is the inverse of CODE2 and vice versa. Define
+ this to return 0 if the target has conditional execution
+ predicates that cannot be reversed safely. If no expansion is
+ specified, this macro is defined as follows:
+
+ #define REVERSE_CONDEXEC_PREDICATES_P (x, y) \
+ ((x) == reverse_condition (y))
+
+
+\1f
+File: gccint.info, Node: Costs, Next: Scheduling, Prev: Condition Code, Up: Target Macros
+
+10.16 Describing Relative Costs of Operations
+=============================================
+
+These macros let you describe the relative speed of various operations
+on the target machine.
+
+`CONST_COSTS (X, CODE, OUTER_CODE)'
+ A part of a C `switch' statement that describes the relative costs
+ of constant RTL expressions. It must contain `case' labels for
+ expression codes `const_int', `const', `symbol_ref', `label_ref'
+ and `const_double'. Each case must ultimately reach a `return'
+ statement to return the relative cost of the use of that kind of
+ constant value in an expression. The cost may depend on the
+ precise value of the constant, which is available for examination
+ in X, and the rtx code of the expression in which it is contained,
+ found in OUTER_CODE.
+
+ CODE is the expression code--redundant, since it can be obtained
+ with `GET_CODE (X)'.
+
+`RTX_COSTS (X, CODE, OUTER_CODE)'
+ Like `CONST_COSTS' but applies to nonconstant RTL expressions.
+ This can be used, for example, to indicate how costly a multiply
+ instruction is. In writing this macro, you can use the construct
+ `COSTS_N_INSNS (N)' to specify a cost equal to N fast
+ instructions. OUTER_CODE is the code of the expression in which X
+ is contained.
+
+ This macro is optional; do not define it if the default cost
+ assumptions are adequate for the target machine.
+
+`DEFAULT_RTX_COSTS (X, CODE, OUTER_CODE)'
+ This macro, if defined, is called for any case not handled by the
+ `RTX_COSTS' or `CONST_COSTS' macros. This eliminates the need to
+ put case labels into the macro, but the code, or any functions it
+ calls, must assume that the RTL in X could be of any type that has
+ not already been handled. The arguments are the same as for
+ `RTX_COSTS', and the macro should execute a return statement giving
+ the cost of any RTL expressions that it can handle. The default
+ cost calculation is used for any RTL for which this macro does not
+ return a value.
+
+ This macro is optional; do not define it if the default cost
+ assumptions are adequate for the target machine.
+
+`ADDRESS_COST (ADDRESS)'
+ An expression giving the cost of an addressing mode that contains
+ ADDRESS. If not defined, the cost is computed from the ADDRESS
+ expression and the `CONST_COSTS' values.
+
+ For most CISC machines, the default cost is a good approximation
+ of the true cost of the addressing mode. However, on RISC
+ machines, all instructions normally have the same length and
+ execution time. Hence all addresses will have equal costs.
+
+ In cases where more than one form of an address is known, the form
+ with the lowest cost will be used. If multiple forms have the
+ same, lowest, cost, the one that is the most complex will be used.
+
+ For example, suppose an address that is equal to the sum of a
+ register and a constant is used twice in the same basic block.
+ When this macro is not defined, the address will be computed in a
+ register and memory references will be indirect through that
+ register. On machines where the cost of the addressing mode
+ containing the sum is no higher than that of a simple indirect
+ reference, this will produce an additional instruction and
+ possibly require an additional register. Proper specification of
+ this macro eliminates this overhead for such machines.
+
+ Similar use of this macro is made in strength reduction of loops.
+
+ ADDRESS need not be valid as an address. In such a case, the cost
+ is not relevant and can be any value; invalid addresses need not be
+ assigned a different cost.
+
+ On machines where an address involving more than one register is as
+ cheap as an address computation involving only one register,
+ defining `ADDRESS_COST' to reflect this can cause two registers to
+ be live over a region of code where only one would have been if
+ `ADDRESS_COST' were not defined in that manner. This effect should
+ be considered in the definition of this macro. Equivalent costs
+ should probably only be given to addresses with different numbers
+ of registers on machines with lots of registers.
+
+ This macro will normally either not be defined or be defined as a
+ constant.
+
+`REGISTER_MOVE_COST (MODE, FROM, TO)'
+ A C expression for the cost of moving data of mode MODE from a
+ register in class FROM to one in class TO. The classes are
+ expressed using the enumeration values such as `GENERAL_REGS'. A
+ value of 2 is the default; other values are interpreted relative to
+ that.
+
+ It is not required that the cost always equal 2 when FROM is the
+ same as TO; on some machines it is expensive to move between
+ registers if they are not general registers.
+
+ If reload sees an insn consisting of a single `set' between two
+ hard registers, and if `REGISTER_MOVE_COST' applied to their
+ classes returns a value of 2, reload does not check to ensure that
+ the constraints of the insn are met. Setting a cost of other than
+ 2 will allow reload to verify that the constraints are met. You
+ should do this if the `movM' pattern's constraints do not allow
+ such copying.
+
+`MEMORY_MOVE_COST (MODE, CLASS, IN)'
+ A C expression for the cost of moving data of mode MODE between a
+ register of class CLASS and memory; IN is zero if the value is to
+ be written to memory, nonzero if it is to be read in. This cost
+ is relative to those in `REGISTER_MOVE_COST'. If moving between
+ registers and memory is more expensive than between two registers,
+ you should define this macro to express the relative cost.
+
+ If you do not define this macro, GCC uses a default cost of 4 plus
+ the cost of copying via a secondary reload register, if one is
+ needed. If your machine requires a secondary reload register to
+ copy between memory and a register of CLASS but the reload
+ mechanism is more complex than copying via an intermediate, define
+ this macro to reflect the actual cost of the move.
+
+ GCC defines the function `memory_move_secondary_cost' if secondary
+ reloads are needed. It computes the costs due to copying via a
+ secondary register. If your machine copies from memory using a
+ secondary register in the conventional way but the default base
+ value of 4 is not correct for your machine, define this macro to
+ add some other value to the result of that function. The
+ arguments to that function are the same as to this macro.
+
+`BRANCH_COST'
+ A C expression for the cost of a branch instruction. A value of 1
+ is the default; other values are interpreted relative to that.
+
+ Here are additional macros which do not specify precise relative
+costs, but only that certain actions are more expensive than GCC would
+ordinarily expect.
+
+`SLOW_BYTE_ACCESS'
+ Define this macro as a C expression which is nonzero if accessing
+ less than a word of memory (i.e. a `char' or a `short') is no
+ faster than accessing a word of memory, i.e., if such access
+ require more than one instruction or if there is no difference in
+ cost between byte and (aligned) word loads.
+
+ When this macro is not defined, the compiler will access a field by
+ finding the smallest containing object; when it is defined, a
+ fullword load will be used if alignment permits. Unless bytes
+ accesses are faster than word accesses, using word accesses is
+ preferable since it may eliminate subsequent memory access if
+ subsequent accesses occur to other fields in the same word of the
+ structure, but to different bytes.
+
+`SLOW_UNALIGNED_ACCESS (MODE, ALIGNMENT)'
+ Define this macro to be the value 1 if memory accesses described
+ by the MODE and ALIGNMENT parameters have a cost many times greater
+ than aligned accesses, for example if they are emulated in a trap
+ handler.
+
+ When this macro is nonzero, the compiler will act as if
+ `STRICT_ALIGNMENT' were nonzero when generating code for block
+ moves. This can cause significantly more instructions to be
+ produced. Therefore, do not set this macro nonzero if unaligned
+ accesses only add a cycle or two to the time for a memory access.
+
+ If the value of this macro is always zero, it need not be defined.
+ If this macro is defined, it should produce a nonzero value when
+ `STRICT_ALIGNMENT' is nonzero.
+
+`DONT_REDUCE_ADDR'
+ Define this macro to inhibit strength reduction of memory
+ addresses. (On some machines, such strength reduction seems to do
+ harm rather than good.)
+
+`MOVE_RATIO'
+ The threshold of number of scalar memory-to-memory move insns,
+ _below_ which a sequence of insns should be generated instead of a
+ string move insn or a library call. Increasing the value will
+ always make code faster, but eventually incurs high cost in
+ increased code size.
+
+ Note that on machines where the corresponding move insn is a
+ `define_expand' that emits a sequence of insns, this macro counts
+ the number of such sequences.
+
+ If you don't define this, a reasonable default is used.
+
+`MOVE_BY_PIECES_P (SIZE, ALIGNMENT)'
+ A C expression used to determine whether `move_by_pieces' will be
+ used to copy a chunk of memory, or whether some other block move
+ mechanism will be used. Defaults to 1 if `move_by_pieces_ninsns'
+ returns less than `MOVE_RATIO'.
+
+`MOVE_MAX_PIECES'
+ A C expression used by `move_by_pieces' to determine the largest
+ unit a load or store used to copy memory is. Defaults to
+ `MOVE_MAX'.
+
+`USE_LOAD_POST_INCREMENT (MODE)'
+ A C expression used to determine whether a load postincrement is a
+ good thing to use for a given mode. Defaults to the value of
+ `HAVE_POST_INCREMENT'.
+
+`USE_LOAD_POST_DECREMENT (MODE)'
+ A C expression used to determine whether a load postdecrement is a
+ good thing to use for a given mode. Defaults to the value of
+ `HAVE_POST_DECREMENT'.
+
+`USE_LOAD_PRE_INCREMENT (MODE)'
+ A C expression used to determine whether a load preincrement is a
+ good thing to use for a given mode. Defaults to the value of
+ `HAVE_PRE_INCREMENT'.
+
+`USE_LOAD_PRE_DECREMENT (MODE)'
+ A C expression used to determine whether a load predecrement is a
+ good thing to use for a given mode. Defaults to the value of
+ `HAVE_PRE_DECREMENT'.
+
+`USE_STORE_POST_INCREMENT (MODE)'
+ A C expression used to determine whether a store postincrement is
+ a good thing to use for a given mode. Defaults to the value of
+ `HAVE_POST_INCREMENT'.
+
+`USE_STORE_POST_DECREMENT (MODE)'
+ A C expression used to determine whether a store postdecrement is
+ a good thing to use for a given mode. Defaults to the value of
+ `HAVE_POST_DECREMENT'.
+
+`USE_STORE_PRE_INCREMENT (MODE)'
+ This macro is used to determine whether a store preincrement is a
+ good thing to use for a given mode. Defaults to the value of
+ `HAVE_PRE_INCREMENT'.
+
+`USE_STORE_PRE_DECREMENT (MODE)'
+ This macro is used to determine whether a store predecrement is a
+ good thing to use for a given mode. Defaults to the value of
+ `HAVE_PRE_DECREMENT'.
+
+`NO_FUNCTION_CSE'
+ Define this macro if it is as good or better to call a constant
+ function address than to call an address kept in a register.
+
+`NO_RECURSIVE_FUNCTION_CSE'
+ Define this macro if it is as good or better for a function to call
+ itself with an explicit address than to call an address kept in a
+ register.
+
+\1f
+File: gccint.info, Node: Scheduling, Next: Sections, Prev: Costs, Up: Target Macros
+
+10.17 Adjusting the Instruction Scheduler
+=========================================
+
+The instruction scheduler may need a fair amount of machine-specific
+adjustment in order to produce good code. GCC provides several target
+hooks for this purpose. It is usually enough to define just a few of
+them: try the first ones in this list first.
+
+ -- Target Hook: int TARGET_SCHED_ISSUE_RATE (void)
+ This hook returns the maximum number of instructions that can ever
+ issue at the same time on the target machine. The default is one.
+ This value must be constant over the entire compilation. If you
+ need it to vary depending on what the instructions are, you must
+ use `TARGET_SCHED_VARIABLE_ISSUE'.
+
+ -- Target Hook: int TARGET_SCHED_VARIABLE_ISSUE (FILE *FILE, int
+ VERBOSE, rtx INSN, int MORE)
+ This hook is executed by the scheduler after it has scheduled an
+ insn from the ready list. It should return the number of insns
+ which can still be issued in the current cycle. Normally this is
+ `MORE - 1'. You should define this hook if some insns take more
+ machine resources than others, so that fewer insns can follow them
+ in the same cycle. FILE is either a null pointer, or a stdio
+ stream to write any debug output to. VERBOSE is the verbose level
+ provided by `-fsched-verbose-N'. INSN is the instruction that was
+ scheduled.
+
+ -- Target Hook: int TARGET_SCHED_ADJUST_COST (rtx INSN, rtx LINK, rtx
+ DEP_INSN, int COST)
+ This function corrects the value of COST based on the relationship
+ between INSN and DEP_INSN through the dependence LINK. It should
+ return the new value. The default is to make no adjustment to
+ COST. This can be used for example to specify to the scheduler
+ that an output- or anti-dependence does not incur the same cost as
+ a data-dependence.
+
+ -- Target Hook: int TARGET_SCHED_ADJUST_PRIORITY (rtx INSN, int
+ PRIORITY)
+ This hook adjusts the integer scheduling priority PRIORITY of
+ INSN. It should return the new priority. Reduce the priority to
+ execute INSN earlier, increase the priority to execute INSN later.
+ Do not define this hook if you do not need to adjust the
+ scheduling priorities of insns.
+
+ -- Target Hook: int TARGET_SCHED_REORDER (FILE *FILE, int VERBOSE, rtx
+ *READY, int *N_READYP, int CLOCK)
+ This hook is executed by the scheduler after it has scheduled the
+ ready list, to allow the machine description to reorder it (for
+ example to combine two small instructions together on `VLIW'
+ machines). FILE is either a null pointer, or a stdio stream to
+ write any debug output to. VERBOSE is the verbose level provided
+ by `-fsched-verbose-N'. READY is a pointer to the ready list of
+ instructions that are ready to be scheduled. N_READYP is a
+ pointer to the number of elements in the ready list. The scheduler
+ reads the ready list in reverse order, starting with
+ READY[*N_READYP-1] and going to READY[0]. CLOCK is the timer tick
+ of the scheduler. You may modify the ready list and the number of
+ ready insns. The return value is the number of insns that can
+ issue this cycle; normally this is just `issue_rate'. See also
+ `TARGET_SCHED_REORDER2'.
+
+ -- Target Hook: int TARGET_SCHED_REORDER2 (FILE *FILE, int VERBOSE,
+ rtx *READY, int *N_READY, CLOCK)
+ Like `TARGET_SCHED_REORDER', but called at a different time. That
+ function is called whenever the scheduler starts a new cycle.
+ This one is called once per iteration over a cycle, immediately
+ after `TARGET_SCHED_VARIABLE_ISSUE'; it can reorder the ready list
+ and return the number of insns to be scheduled in the same cycle.
+ Defining this hook can be useful if there are frequent situations
+ where scheduling one insn causes other insns to become ready in
+ the same cycle. These other insns can then be taken into account
+ properly.
+
+ -- Target Hook: void TARGET_SCHED_INIT (FILE *FILE, int VERBOSE, int
+ MAX_READY)
+ This hook is executed by the scheduler at the beginning of each
+ block of instructions that are to be scheduled. FILE is either a
+ null pointer, or a stdio stream to write any debug output to.
+ VERBOSE is the verbose level provided by `-fsched-verbose-N'.
+ MAX_READY is the maximum number of insns in the current scheduling
+ region that can be live at the same time. This can be used to
+ allocate scratch space if it is needed, e.g. by
+ `TARGET_SCHED_REORDER'.
+
+ -- Target Hook: void TARGET_SCHED_FINISH (FILE *FILE, int VERBOSE)
+ This hook is executed by the scheduler at the end of each block of
+ instructions that are to be scheduled. It can be used to perform
+ cleanup of any actions done by the other scheduling hooks. FILE
+ is either a null pointer, or a stdio stream to write any debug
+ output to. VERBOSE is the verbose level provided by
+ `-fsched-verbose-N'.
+
+ -- Target Hook: rtx TARGET_SCHED_CYCLE_DISPLAY (int CLOCK, rtx LAST)
+ This hook is called in verbose mode only, at the beginning of each
+ pass over a basic block. It should insert an insn into the chain
+ after LAST, which has no effect, but records the value CLOCK in
+ RTL dumps and assembly output. Define this hook only if you need
+ this level of detail about what the scheduler is doing.
+
+\1f
+File: gccint.info, Node: Sections, Next: PIC, Prev: Scheduling, Up: Target Macros
+
+10.18 Dividing the Output into Sections (Texts, Data, ...)
+==========================================================
+
+An object file is divided into sections containing different types of
+data. In the most common case, there are three sections: the "text
+section", which holds instructions and read-only data; the "data
+section", which holds initialized writable data; and the "bss section",
+which holds uninitialized data. Some systems have other kinds of
+sections.
+
+ The compiler must tell the assembler when to switch sections. These
+macros control what commands to output to tell the assembler this. You
+can also define additional sections.
+
+`TEXT_SECTION_ASM_OP'
+ A C expression whose value is a string, including spacing,
+ containing the assembler operation that should precede
+ instructions and read-only data. Normally `"\t.text"' is right.
+
+`TEXT_SECTION'
+ A C statement that switches to the default section containing
+ instructions. Normally this is not needed, as simply defining
+ `TEXT_SECTION_ASM_OP' is enough. The MIPS port uses this to sort
+ all functions after all data declarations.
+
+`DATA_SECTION_ASM_OP'
+ A C expression whose value is a string, including spacing,
+ containing the assembler operation to identify the following data
+ as writable initialized data. Normally `"\t.data"' is right.
+
+`SHARED_SECTION_ASM_OP'
+ If defined, a C expression whose value is a string, including
+ spacing, containing the assembler operation to identify the
+ following data as shared data. If not defined,
+ `DATA_SECTION_ASM_OP' will be used.
+
+`BSS_SECTION_ASM_OP'
+ If defined, a C expression whose value is a string, including
+ spacing, containing the assembler operation to identify the
+ following data as uninitialized global data. If not defined, and
+ neither `ASM_OUTPUT_BSS' nor `ASM_OUTPUT_ALIGNED_BSS' are defined,
+ uninitialized global data will be output in the data section if
+ `-fno-common' is passed, otherwise `ASM_OUTPUT_COMMON' will be
+ used.
+
+`SHARED_BSS_SECTION_ASM_OP'
+ If defined, a C expression whose value is a string, including
+ spacing, containing the assembler operation to identify the
+ following data as uninitialized global shared data. If not
+ defined, and `BSS_SECTION_ASM_OP' is, the latter will be used.
+
+`INIT_SECTION_ASM_OP'
+ If defined, a C expression whose value is a string, including
+ spacing, containing the assembler operation to identify the
+ following data as initialization code. If not defined, GCC will
+ assume such a section does not exist.
+
+`FINI_SECTION_ASM_OP'
+ If defined, a C expression whose value is a string, including
+ spacing, containing the assembler operation to identify the
+ following data as finalization code. If not defined, GCC will
+ assume such a section does not exist.
+
+`CRT_CALL_STATIC_FUNCTION (SECTION_OP, FUNCTION)'
+ If defined, an ASM statement that switches to a different section
+ via SECTION_OP, calls FUNCTION, and switches back to the text
+ section. This is used in `crtstuff.c' if `INIT_SECTION_ASM_OP' or
+ `FINI_SECTION_ASM_OP' to calls to initialization and finalization
+ functions from the init and fini sections. By default, this macro
+ uses a simple function call. Some ports need hand-crafted
+ assembly code to avoid dependencies on registers initialized in
+ the function prologue or to ensure that constant pools don't end
+ up too far way in the text section.
+
+`FORCE_CODE_SECTION_ALIGN'
+ If defined, an ASM statement that aligns a code section to some
+ arbitrary boundary. This is used to force all fragments of the
+ `.init' and `.fini' sections to have to same alignment and thus
+ prevent the linker from having to add any padding.
+
+`EXTRA_SECTIONS'
+ A list of names for sections other than the standard two, which are
+ `in_text' and `in_data'. You need not define this macro on a
+ system with no other sections (that GCC needs to use).
+
+`EXTRA_SECTION_FUNCTIONS'
+ One or more functions to be defined in `varasm.c'. These
+ functions should do jobs analogous to those of `text_section' and
+ `data_section', for your additional sections. Do not define this
+ macro if you do not define `EXTRA_SECTIONS'.
+
+`READONLY_DATA_SECTION'
+ On most machines, read-only variables, constants, and jump tables
+ are placed in the text section. If this is not the case on your
+ machine, this macro should be defined to be the name of a function
+ (either `data_section' or a function defined in `EXTRA_SECTIONS')
+ that switches to the section to be used for read-only items.
+
+ If these items should be placed in the text section, this macro
+ should not be defined.
+
+`SELECT_SECTION (EXP, RELOC, ALIGN)'
+ A C statement or statements to switch to the appropriate section
+ for output of EXP. You can assume that EXP is either a `VAR_DECL'
+ node or a constant of some sort. RELOC indicates whether the
+ initial value of EXP requires link-time relocations. Bit 1 is set
+ when variable contains local relocations only, while bit 2 is set
+ for global relocations. Select the section by calling
+ `text_section' or one of the alternatives for other sections.
+ ALIGN is the constant alignment in bits.
+
+ Do not define this macro if you put all read-only variables and
+ constants in the read-only data section (usually the text section).
+
+`SELECT_RTX_SECTION (MODE, RTX, ALIGN)'
+ A C statement or statements to switch to the appropriate section
+ for output of RTX in mode MODE. You can assume that RTX is some
+ kind of constant in RTL. The argument MODE is redundant except in
+ the case of a `const_int' rtx. Select the section by calling
+ `text_section' or one of the alternatives for other sections.
+ ALIGN is the constant alignment in bits.
+
+ Do not define this macro if you put all constants in the read-only
+ data section.
+
+`JUMP_TABLES_IN_TEXT_SECTION'
+ Define this macro to be an expression with a nonzero value if jump
+ tables (for `tablejump' insns) should be output in the text
+ section, along with the assembler instructions. Otherwise, the
+ readonly data section is used.
+
+ This macro is irrelevant if there is no separate readonly data
+ section.
+
+`ENCODE_SECTION_INFO (DECL)'
+ Define this macro if references to a symbol or a constant must be
+ treated differently depending on something about the variable or
+ function named by the symbol (such as what section it is in).
+
+ The macro definition, if any, is executed under two circumstances.
+ One is immediately after the rtl for DECL that represents a
+ variable or a function has been created and stored in `DECL_RTL
+ (DECL)'. The value of the rtl will be a `mem' whose address is a
+ `symbol_ref'. The other is immediately after the rtl for DECL
+ that represents a constant has been created and stored in
+ `TREE_CST_RTL (DECL)'. The macro is called once for each distinct
+ constant in a source file.
+
+ The usual thing for this macro to do is to record a flag in the
+ `symbol_ref' (such as `SYMBOL_REF_FLAG') or to store a modified
+ name string in the `symbol_ref' (if one bit is not enough
+ information).
+
+`STRIP_NAME_ENCODING (VAR, SYM_NAME)'
+ Decode SYM_NAME and store the real name part in VAR, sans the
+ characters that encode section info. Define this macro if
+ `ENCODE_SECTION_INFO' alters the symbol's name string.
+
+`UNIQUE_SECTION (DECL, RELOC)'
+ A C statement to build up a unique section name, expressed as a
+ `STRING_CST' node, and assign it to `DECL_SECTION_NAME (DECL)'.
+ RELOC indicates whether the initial value of EXP requires
+ link-time relocations. If you do not define this macro, GCC will
+ use the symbol name prefixed by `.' as the section name. Note -
+ this macro can now be called for uninitialized data items as well
+ as initialized data and functions.
+
+\1f
+File: gccint.info, Node: PIC, Next: Assembler Format, Prev: Sections, Up: Target Macros
+
+10.19 Position Independent Code
+===============================
+
+This section describes macros that help implement generation of position
+independent code. Simply defining these macros is not enough to
+generate valid PIC; you must also add support to the macros
+`GO_IF_LEGITIMATE_ADDRESS' and `PRINT_OPERAND_ADDRESS', as well as
+`LEGITIMIZE_ADDRESS'. You must modify the definition of `movsi' to do
+something appropriate when the source operand contains a symbolic
+address. You may also need to alter the handling of switch statements
+so that they use relative addresses.
+
+`PIC_OFFSET_TABLE_REGNUM'
+ The register number of the register used to address a table of
+ static data addresses in memory. In some cases this register is
+ defined by a processor's "application binary interface" (ABI).
+ When this macro is defined, RTL is generated for this register
+ once, as with the stack pointer and frame pointer registers. If
+ this macro is not defined, it is up to the machine-dependent files
+ to allocate such a register (if necessary). Note that this
+ register must be fixed when in use (e.g. when `flag_pic' is true).
+
+`PIC_OFFSET_TABLE_REG_CALL_CLOBBERED'
+ Define this macro if the register defined by
+ `PIC_OFFSET_TABLE_REGNUM' is clobbered by calls. Do not define
+ this macro if `PIC_OFFSET_TABLE_REGNUM' is not defined.
+
+`FINALIZE_PIC'
+ By generating position-independent code, when two different
+ programs (A and B) share a common library (libC.a), the text of
+ the library can be shared whether or not the library is linked at
+ the same address for both programs. In some of these
+ environments, position-independent code requires not only the use
+ of different addressing modes, but also special code to enable the
+ use of these addressing modes.
+
+ The `FINALIZE_PIC' macro serves as a hook to emit these special
+ codes once the function is being compiled into assembly code, but
+ not before. (It is not done before, because in the case of
+ compiling an inline function, it would lead to multiple PIC
+ prologues being included in functions which used inline functions
+ and were compiled to assembly language.)
+
+`LEGITIMATE_PIC_OPERAND_P (X)'
+ A C expression that is nonzero if X is a legitimate immediate
+ operand on the target machine when generating position independent
+ code. You can assume that X satisfies `CONSTANT_P', so you need
+ not check this. You can also assume FLAG_PIC is true, so you need
+ not check it either. You need not define this macro if all
+ constants (including `SYMBOL_REF') can be immediate operands when
+ generating position independent code.
+
+\1f
+File: gccint.info, Node: Assembler Format, Next: Debugging Info, Prev: PIC, Up: Target Macros
+
+10.20 Defining the Output Assembler Language
+============================================
+
+This section describes macros whose principal purpose is to describe how
+to write instructions in assembler language--rather than what the
+instructions do.
* Menu:
-* Namespaces:: Member functions, types, etc.
-* Classes:: Members, bases, friends, etc.
-
-\1f
-File: gccint.info, Node: Namespaces, Next: Classes, Up: Scopes
-
-Namespaces
-----------
-
- A namespace is represented by a `NAMESPACE_DECL' node.
-
- However, except for the fact that it is distinguished as the root of
-the representation, the global namespace is no different from any other
-namespace. Thus, in what follows, we describe namespaces generally,
-rather than the global namespace in particular.
-
- The following macros and functions can be used on a `NAMESPACE_DECL':
-
-`DECL_NAME'
- This macro is used to obtain the `IDENTIFIER_NODE' corresponding to
- the unqualified name of the name of the namespace (*note
- Identifiers::). The name of the global namespace is `::', even
- though in C++ the global namespace is unnamed. However, you
- should use comparison with `global_namespace', rather than
- `DECL_NAME' to determine whether or not a namespaces is the global
- one. An unnamed namespace will have a `DECL_NAME' equal to
- `anonymous_namespace_name'. Within a single translation unit, all
- unnamed namespaces will have the same name.
-
-`DECL_CONTEXT'
- This macro returns the enclosing namespace. The `DECL_CONTEXT' for
- the `global_namespace' is `NULL_TREE'.
-
-`DECL_NAMESPACE_ALIAS'
- If this declaration is for a namespace alias, then
- `DECL_NAMESPACE_ALIAS' is the namespace for which this one is an
- alias.
-
- Do not attempt to use `cp_namespace_decls' for a namespace which is
- an alias. Instead, follow `DECL_NAMESPACE_ALIAS' links until you
- reach an ordinary, non-alias, namespace, and call
- `cp_namespace_decls' there.
-
-`DECL_NAMESPACE_STD_P'
- This predicate holds if the namespace is the special `::std'
- namespace.
-
-`cp_namespace_decls'
- This function will return the declarations contained in the
- namespace, including types, overloaded functions, other
- namespaces, and so forth. If there are no declarations, this
- function will return `NULL_TREE'. The declarations are connected
- through their `TREE_CHAIN' fields.
-
- Although most entries on this list will be declarations,
- `TREE_LIST' nodes may also appear. In this case, the `TREE_VALUE'
- will be an `OVERLOAD'. The value of the `TREE_PURPOSE' is
- unspecified; back ends should ignore this value. As with the
- other kinds of declarations returned by `cp_namespace_decls', the
- `TREE_CHAIN' will point to the next declaration in this list.
-
- For more information on the kinds of declarations that can occur
- on this list, *Note Declarations::. Some declarations will not
- appear on this list. In particular, no `FIELD_DECL',
- `LABEL_DECL', or `PARM_DECL' nodes will appear here.
-
- This function cannot be used with namespaces that have
- `DECL_NAMESPACE_ALIAS' set.
-
-
-\1f
-File: gccint.info, Node: Classes, Prev: Namespaces, Up: Scopes
-
-Classes
--------
-
- A class type is represented by either a `RECORD_TYPE' or a
-`UNION_TYPE'. A class declared with the `union' tag is represented by
-a `UNION_TYPE', while classes declared with either the `struct' or the
-`class' tag are represented by `RECORD_TYPE's. You can use the
-`CLASSTYPE_DECLARED_CLASS' macro to discern whether or not a particular
-type is a `class' as opposed to a `struct'. This macro will be true
-only for classes declared with the `class' tag.
-
- Almost all non-function members are available on the `TYPE_FIELDS'
-list. Given one member, the next can be found by following the
-`TREE_CHAIN'. You should not depend in any way on the order in which
-fields appear on this list. All nodes on this list will be `DECL'
-nodes. A `FIELD_DECL' is used to represent a non-static data member, a
-`VAR_DECL' is used to represent a static data member, and a `TYPE_DECL'
-is used to represent a type. Note that the `CONST_DECL' for an
-enumeration constant will appear on this list, if the enumeration type
-was declared in the class. (Of course, the `TYPE_DECL' for the
-enumeration type will appear here as well.) There are no entries for
-base classes on this list. In particular, there is no `FIELD_DECL' for
-the "base-class portion" of an object.
-
- The `TYPE_VFIELD' is a compiler-generated field used to point to
-virtual function tables. It may or may not appear on the `TYPE_FIELDS'
-list. However, back ends should handle the `TYPE_VFIELD' just like all
-the entries on the `TYPE_FIELDS' list.
-
- The function members are available on the `TYPE_METHODS' list.
-Again, subsequent members are found by following the `TREE_CHAIN'
-field. If a function is overloaded, each of the overloaded functions
-appears; no `OVERLOAD' nodes appear on the `TYPE_METHODS' list.
-Implicitly declared functions (including default constructors, copy
-constructors, assignment operators, and destructors) will appear on
-this list as well.
-
- Every class has an associated "binfo", which can be obtained with
-`TYPE_BINFO'. Binfos are used to represent base-classes. The binfo
-given by `TYPE_BINFO' is the degenerate case, whereby every class is
-considered to be its own base-class. The base classes for a particular
-binfo can be obtained with `BINFO_BASETYPES'. These base-classes are
-themselves binfos. The class type associated with a binfo is given by
-`BINFO_TYPE'. It is always the case that `BINFO_TYPE (TYPE_BINFO (x))'
-is the same type as `x', up to qualifiers. However, it is not always
-the case that `TYPE_BINFO (BINFO_TYPE (y))' is always the same binfo as
-`y'. The reason is that if `y' is a binfo representing a base-class
-`B' of a derived class `D', then `BINFO_TYPE (y)' will be `B', and
-`TYPE_BINFO (BINFO_TYPE (y))' will be `B' as its own base-class, rather
-than as a base-class of `D'.
-
- The `BINFO_BASETYPES' is a `TREE_VEC' (*note Containers::). Base
-types appear in left-to-right order in this vector. You can tell
-whether or `public', `protected', or `private' inheritance was used by
-using the `TREE_VIA_PUBLIC', `TREE_VIA_PROTECTED', and
-`TREE_VIA_PRIVATE' macros. Each of these macros takes a `BINFO' and is
-true if and only if the indicated kind of inheritance was used. If
-`TREE_VIA_VIRTUAL' holds of a binfo, then its `BINFO_TYPE' was
-inherited from virtually.
-
- The following macros can be used on a tree node representing a
-class-type.
-
-`LOCAL_CLASS_P'
- This predicate holds if the class is local class _i.e._ declared
- inside a function body.
-
-`TYPE_POLYMORPHIC_P'
- This predicate holds if the class has at least one virtual function
- (declared or inherited).
-
-`TYPE_HAS_DEFAULT_CONSTRUCTOR'
- This predicate holds whenever its argument represents a class-type
- with default constructor.
-
-`CLASSTYPE_HAS_MUTABLE'
-
-`TYPE_HAS_MUTABLE_P'
- These predicates hold for a class-type having a mutable data
- member.
-
-`CLASSTYPE_NON_POD_P'
- This predicate holds only for class-types that are not PODs.
-
-`TYPE_HAS_NEW_OPERATOR'
- This predicate holds for a class-type that defines `operator new'.
-
-`TYPE_HAS_ARRAY_NEW_OPERATOR'
- This predicate holds for a class-type for which `operator new[]'
- is defined.
-
-`TYPE_OVERLOADS_CALL_EXPR'
- This predicate holds for class-type for which the function call
- `operator()' is overloaded.
-
-`TYPE_OVERLOADS_ARRAY_REF'
- This predicate holds for a class-type that overloads `operator[]'
-
-`TYPE_OVERLOADS_ARROW'
- This predicate holds for a class-type for which `operator->' is
- overloaded.
-
-
-\1f
-File: gccint.info, Node: Declarations, Next: Attributes, Prev: Functions, Up: Trees
-
-Declarations
-============
-
- This section covers the various kinds of declarations that appear in
-the internal representation, except for declarations of functions
-(represented by `FUNCTION_DECL' nodes), which are described in *Note
-Functions::.
-
- Some macros can be used with any kind of declaration. These include:
-`DECL_NAME'
- This macro returns an `IDENTIFIER_NODE' giving the name of the
- entity.
-
-`TREE_TYPE'
- This macro returns the type of the entity declared.
-
-`DECL_SOURCE_FILE'
- This macro returns the name of the file in which the entity was
- declared, as a `char*'. For an entity declared implicitly by the
- compiler (like `__builtin_memcpy'), this will be the string
- `"<internal>"'.
-
-`DECL_SOURCE_LINE'
- This macro returns the line number at which the entity was
- declared, as an `int'.
-
-`DECL_ARTIFICIAL'
- This predicate holds if the declaration was implicitly generated
- by the compiler. For example, this predicate will hold of an
- implicitly declared member function, or of the `TYPE_DECL'
- implicitly generated for a class type. Recall that in C++ code
- like:
- struct S {};
-
- is roughly equivalent to C code like:
- struct S {};
- typedef struct S S;
- The implicitly generated `typedef' declaration is represented by a
- `TYPE_DECL' for which `DECL_ARTIFICIAL' holds.
-
-`DECL_NAMESPACE_SCOPE_P'
- This predicate holds if the entity was declared at a namespace
- scope.
-
-`DECL_CLASS_SCOPE_P'
- This predicate holds if the entity was declared at a class scope.
-
-`DECL_FUNCTION_SCOPE_P'
- This predicate holds if the entity was declared inside a function
- body.
-
-
- The various kinds of declarations include:
-`LABEL_DECL'
- These nodes are used to represent labels in function bodies. For
- more information, see *Note Functions::. These nodes only appear
- in block scopes.
-
-`CONST_DECL'
- These nodes are used to represent enumeration constants. The
- value of the constant is given by `DECL_INITIAL' which will be an
- `INTEGER_CST' with the same type as the `TREE_TYPE' of the
- `CONST_DECL', i.e., an `ENUMERAL_TYPE'.
-
-`RESULT_DECL'
- These nodes represent the value returned by a function. When a
- value is assigned to a `RESULT_DECL', that indicates that the
- value should be returned, via bitwise copy, by the function. You
- can use `DECL_SIZE' and `DECL_ALIGN' on a `RESULT_DECL', just as
- with a `VAR_DECL'.
-
-`TYPE_DECL'
- These nodes represent `typedef' declarations. The `TREE_TYPE' is
- the type declared to have the name given by `DECL_NAME'. In some
- cases, there is no associated name.
-
-`VAR_DECL'
- These nodes represent variables with namespace or block scope, as
- well as static data members. The `DECL_SIZE' and `DECL_ALIGN' are
- analogous to `TYPE_SIZE' and `TYPE_ALIGN'. For a declaration, you
- should always use the `DECL_SIZE' and `DECL_ALIGN' rather than the
- `TYPE_SIZE' and `TYPE_ALIGN' given by the `TREE_TYPE', since
- special attributes may have been applied to the variable to give
- it a particular size and alignment. You may use the predicates
- `DECL_THIS_STATIC' or `DECL_THIS_EXTERN' to test whether the
- storage class specifiers `static' or `extern' were used to declare
- a variable.
-
- If this variable is initialized (but does not require a
- constructor), the `DECL_INITIAL' will be an expression for the
- initializer. The initializer should be evaluated, and a bitwise
- copy into the variable performed. If the `DECL_INITIAL' is the
- `error_mark_node', there is an initializer, but it is given by an
- explicit statement later in the code; no bitwise copy is required.
-
- GCC provides an extension that allows either automatic variables,
- or global variables, to be placed in particular registers. This
- extension is being used for a particular `VAR_DECL' if
- `DECL_REGISTER' holds for the `VAR_DECL', and if
- `DECL_ASSEMBLER_NAME' is not equal to `DECL_NAME'. In that case,
- `DECL_ASSEMBLER_NAME' is the name of the register into which the
- variable will be placed.
-
-`PARM_DECL'
- Used to represent a parameter to a function. Treat these nodes
- similarly to `VAR_DECL' nodes. These nodes only appear in the
- `DECL_ARGUMENTS' for a `FUNCTION_DECL'.
-
- The `DECL_ARG_TYPE' for a `PARM_DECL' is the type that will
- actually be used when a value is passed to this function. It may
- be a wider type than the `TREE_TYPE' of the parameter; for
- example, the ordinary type might be `short' while the
- `DECL_ARG_TYPE' is `int'.
-
-`FIELD_DECL'
- These nodes represent non-static data members. The `DECL_SIZE' and
- `DECL_ALIGN' behave as for `VAR_DECL' nodes. The
- `DECL_FIELD_BITPOS' gives the first bit used for this field, as an
- `INTEGER_CST'. These values are indexed from zero, where zero
- indicates the first bit in the object.
-
- If `DECL_C_BIT_FIELD' holds, this field is a bit-field.
-
-`NAMESPACE_DECL'
- *Note Namespaces::.
-
-`TEMPLATE_DECL'
- These nodes are used to represent class, function, and variable
- (static data member) templates. The
- `DECL_TEMPLATE_SPECIALIZATIONS' are a `TREE_LIST'. The
- `TREE_VALUE' of each node in the list is a `TEMPLATE_DECL's or
- `FUNCTION_DECL's representing specializations (including
- instantiations) of this template. Back ends can safely ignore
- `TEMPLATE_DECL's, but should examine `FUNCTION_DECL' nodes on the
- specializations list just as they would ordinary `FUNCTION_DECL'
- nodes.
-
- For a class template, the `DECL_TEMPLATE_INSTANTIATIONS' list
- contains the instantiations. The `TREE_VALUE' of each node is an
- instantiation of the class. The `DECL_TEMPLATE_SPECIALIZATIONS'
- contains partial specializations of the class.
-
-`USING_DECL'
- Back ends can safely ignore these nodes.
-
-
-\1f
-File: gccint.info, Node: Functions, Next: Declarations, Prev: Scopes, Up: Trees
-
-Functions
-=========
-
- A function is represented by a `FUNCTION_DECL' node. A set of
-overloaded functions is sometimes represented by a `OVERLOAD' node.
-
- An `OVERLOAD' node is not a declaration, so none of the `DECL_'
-macros should be used on an `OVERLOAD'. An `OVERLOAD' node is similar
-to a `TREE_LIST'. Use `OVL_CURRENT' to get the function associated
-with an `OVERLOAD' node; use `OVL_NEXT' to get the next `OVERLOAD' node
-in the list of overloaded functions. The macros `OVL_CURRENT' and
-`OVL_NEXT' are actually polymorphic; you can use them to work with
-`FUNCTION_DECL' nodes as well as with overloads. In the case of a
-`FUNCTION_DECL', `OVL_CURRENT' will always return the function itself,
-and `OVL_NEXT' will always be `NULL_TREE'.
-
- To determine the scope of a function, you can use the
-`DECL_REAL_CONTEXT' macro. This macro will return the class (either a
-`RECORD_TYPE' or a `UNION_TYPE') or namespace (a `NAMESPACE_DECL') of
-which the function is a member. For a virtual function, this macro
-returns the class in which the function was actually defined, not the
-base class in which the virtual declaration occurred. If a friend
-function is defined in a class scope, the `DECL_CLASS_CONTEXT' macro
-can be used to determine the class in which it was defined. For
-example, in
- class C { friend void f() {} };
- the `DECL_REAL_CONTEXT' for `f' will be the `global_namespace', but
-the `DECL_CLASS_CONTEXT' will be the `RECORD_TYPE' for `C'.
-
- The `DECL_REAL_CONTEXT' and `DECL_CLASS_CONTEXT' are not available
-in C; instead you should simply use `DECL_CONTEXT'. In C, the
-`DECL_CONTEXT' for a function maybe another function. This
-representation indicates that the GNU nested function extension is in
-use. For details on the semantics of nested functions, see the GCC
-Manual. The nested function can refer to local variables in its
-containing function. Such references are not explicitly marked in the
-tree structure; back ends must look at the `DECL_CONTEXT' for the
-referenced `VAR_DECL'. If the `DECL_CONTEXT' for the referenced
-`VAR_DECL' is not the same as the function currently being processed,
-and neither `DECL_EXTERNAL' nor `DECL_STATIC' hold, then the reference
-is to a local variable in a containing function, and the back end must
-take appropriate action.
+* File Framework:: Structural information for the assembler file.
+* Data Output:: Output of constants (numbers, strings, addresses).
+* Uninitialized Data:: Output of uninitialized variables.
+* Label Output:: Output and generation of labels.
+* Initialization:: General principles of initialization
+ and termination routines.
+* Macros for Initialization::
+ Specific macros that control the handling of
+ initialization and termination routines.
+* Instruction Output:: Output of actual instructions.
+* Dispatch Tables:: Output of jump tables.
+* Exception Region Output:: Output of exception region code.
+* Alignment Output:: Pseudo ops for alignment and skipping data.
+
+\1f
+File: gccint.info, Node: File Framework, Next: Data Output, Up: Assembler Format
+
+10.20.1 The Overall Framework of an Assembler File
+--------------------------------------------------
+
+This describes the overall framework of an assembler file.
+
+`ASM_FILE_START (STREAM)'
+ A C expression which outputs to the stdio stream STREAM some
+ appropriate text to go at the start of an assembler file.
+
+ Normally this macro is defined to output a line containing
+ `#NO_APP', which is a comment that has no effect on most
+ assemblers but tells the GNU assembler that it can save time by not
+ checking for certain assembler constructs.
+
+ On systems that use SDB, it is necessary to output certain
+ commands; see `attasm.h'.
+
+`ASM_FILE_END (STREAM)'
+ A C expression which outputs to the stdio stream STREAM some
+ appropriate text to go at the end of an assembler file.
+
+ If this macro is not defined, the default is to output nothing
+ special at the end of the file. Most systems don't require any
+ definition.
+
+ On systems that use SDB, it is necessary to output certain
+ commands; see `attasm.h'.
+
+`ASM_COMMENT_START'
+ A C string constant describing how to begin a comment in the target
+ assembler language. The compiler assumes that the comment will
+ end at the end of the line.
+
+`ASM_APP_ON'
+ A C string constant for text to be output before each `asm'
+ statement or group of consecutive ones. Normally this is
+ `"#APP"', which is a comment that has no effect on most assemblers
+ but tells the GNU assembler that it must check the lines that
+ follow for all valid assembler constructs.
+
+`ASM_APP_OFF'
+ A C string constant for text to be output after each `asm'
+ statement or group of consecutive ones. Normally this is
+ `"#NO_APP"', which tells the GNU assembler to resume making the
+ time-saving assumptions that are valid for ordinary compiler
+ output.
+
+`ASM_OUTPUT_SOURCE_FILENAME (STREAM, NAME)'
+ A C statement to output COFF information or DWARF debugging
+ information which indicates that filename NAME is the current
+ source file to the stdio stream STREAM.
+
+ This macro need not be defined if the standard form of output for
+ the file format in use is appropriate.
+
+`OUTPUT_QUOTED_STRING (STREAM, STRING)'
+ A C statement to output the string STRING to the stdio stream
+ STREAM. If you do not call the function `output_quoted_string' in
+ your config files, GCC will only call it to output filenames to
+ the assembler source. So you can use it to canonicalize the format
+ of the filename using this macro.
+
+`ASM_OUTPUT_SOURCE_LINE (STREAM, LINE)'
+ A C statement to output DBX or SDB debugging information before
+ code for line number LINE of the current source file to the stdio
+ stream STREAM.
+
+ This macro need not be defined if the standard form of debugging
+ information for the debugger in use is appropriate.
+
+`ASM_OUTPUT_IDENT (STREAM, STRING)'
+ A C statement to output something to the assembler file to handle a
+ `#ident' directive containing the text STRING. If this macro is
+ not defined, nothing is output for a `#ident' directive.
+
+`OBJC_PROLOGUE'
+ A C statement to output any assembler statements which are
+ required to precede any Objective-C object definitions or message
+ sending. The statement is executed only when compiling an
+ Objective-C program.
+
+ -- Target Hook: void TARGET_ASM_NAMED_SECTION (const char *NAME,
+ unsigned int FLAGS, unsigned int ALIGN)
+ Output assembly directives to switch to section NAME. The section
+ should have attributes as specified by FLAGS, which is a bit mask
+ of the `SECTION_*' flags defined in `output.h'. If ALIGN is
+ nonzero, it contains an alignment in bytes to be used for the
+ section, otherwise some target default should be used. Only
+ targets that must specify an alignment within the section
+ directive need pay attention to ALIGN - we will still use
+ `ASM_OUTPUT_ALIGN'.
+
+ -- Target Hook: bool TARGET_HAVE_NAMED_SECTIONS
+ This flag is true if the target supports
+ `TARGET_ASM_NAMED_SECTION'.
+
+ -- Target Hook: unsigned int TARGET_SECTION_TYPE_FLAGS (tree DECL,
+ const char *NAME, int RELOC)
+ Choose a set of section attributes for use by
+ `TARGET_ASM_NAMED_SECTION' based on a variable or function decl, a
+ section name, and whether or not the declaration's initializer may
+ contain runtime relocations. DECL may be null, in which case
+ read-write data should be assumed.
+
+ The default version if this function handles choosing code vs data,
+ read-only vs read-write data, and `flag_pic'. You should only
+ need to override this if your target has special flags that might
+ be set via `__attribute__'.
+
+\1f
+File: gccint.info, Node: Data Output, Next: Uninitialized Data, Prev: File Framework, Up: Assembler Format
+
+10.20.2 Output of Data
+----------------------
+
+ -- Target Hook: const char * TARGET_ASM_BYTE_OP
+ -- Target Hook: const char * TARGET_ASM_ALIGNED_HI_OP
+ -- Target Hook: const char * TARGET_ASM_ALIGNED_SI_OP
+ -- Target Hook: const char * TARGET_ASM_ALIGNED_DI_OP
+ -- Target Hook: const char * TARGET_ASM_ALIGNED_TI_OP
+ -- Target Hook: const char * TARGET_ASM_UNALIGNED_HI_OP
+ -- Target Hook: const char * TARGET_ASM_UNALIGNED_SI_OP
+ -- Target Hook: const char * TARGET_ASM_UNALIGNED_DI_OP
+ -- Target Hook: const char * TARGET_ASM_UNALIGNED_TI_OP
+ These hooks specify assembly directives for creating certain kinds
+ of integer object. The `TARGET_ASM_BYTE_OP' directive creates a
+ byte-sized object, the `TARGET_ASM_ALIGNED_HI_OP' one creates an
+ aligned two-byte object, and so on. Any of the hooks may be
+ `NULL', indicating that no suitable directive is available.
+
+ The compiler will print these strings at the start of a new line,
+ followed immediately by the object's initial value. In most cases,
+ the string should contain a tab, a pseudo-op, and then another tab.
+
+ -- Target Hook: bool TARGET_ASM_INTEGER (rtx X, unsigned int SIZE, int
+ ALIGNED_P)
+ The `assemble_integer' function uses this hook to output an
+ integer object. X is the object's value, SIZE is its size in
+ bytes and ALIGNED_P indicates whether it is aligned. The function
+ should return `true' if it was able to output the object. If it
+ returns false, `assemble_integer' will try to split the object
+ into smaller parts.
+
+ The default implementation of this hook will use the
+ `TARGET_ASM_BYTE_OP' family of strings, returning `false' when the
+ relevant string is `NULL'.
+
+`OUTPUT_ADDR_CONST_EXTRA (STREAM, X, FAIL)'
+ A C statement to recognize RTX patterns that `output_addr_const'
+ can't deal with, and output assembly code to STREAM corresponding
+ to the pattern X. This may be used to allow machine-dependent
+ `UNSPEC's to appear within constants.
+
+ If `OUTPUT_ADDR_CONST_EXTRA' fails to recognize a pattern, it must
+ `goto fail', so that a standard error message is printed. If it
+ prints an error message itself, by calling, for example,
+ `output_operand_lossage', it may just complete normally.
+
+`ASM_OUTPUT_ASCII (STREAM, PTR, LEN)'
+ A C statement to output to the stdio stream STREAM an assembler
+ instruction to assemble a string constant containing the LEN bytes
+ at PTR. PTR will be a C expression of type `char *' and LEN a C
+ expression of type `int'.
+
+ If the assembler has a `.ascii' pseudo-op as found in the Berkeley
+ Unix assembler, do not define the macro `ASM_OUTPUT_ASCII'.
+
+`ASM_OUTPUT_FDESC (STREAM, DECL, N)'
+ A C statement to output word N of a function descriptor for DECL.
+ This must be defined if `TARGET_VTABLE_USES_DESCRIPTORS' is
+ defined, and is otherwise unused.
+
+`CONSTANT_POOL_BEFORE_FUNCTION'
+ You may define this macro as a C expression. You should define the
+ expression to have a nonzero value if GCC should output the
+ constant pool for a function before the code for the function, or
+ a zero value if GCC should output the constant pool after the
+ function. If you do not define this macro, the usual case, GCC
+ will output the constant pool before the function.
+
+`ASM_OUTPUT_POOL_PROLOGUE (FILE, FUNNAME, FUNDECL, SIZE)'
+ A C statement to output assembler commands to define the start of
+ the constant pool for a function. FUNNAME is a string giving the
+ name of the function. Should the return type of the function be
+ required, it can be obtained via FUNDECL. SIZE is the size, in
+ bytes, of the constant pool that will be written immediately after
+ this call.
+
+ If no constant-pool prefix is required, the usual case, this macro
+ need not be defined.
+
+`ASM_OUTPUT_SPECIAL_POOL_ENTRY (FILE, X, MODE, ALIGN, LABELNO, JUMPTO)'
+ A C statement (with or without semicolon) to output a constant in
+ the constant pool, if it needs special treatment. (This macro
+ need not do anything for RTL expressions that can be output
+ normally.)
+
+ The argument FILE is the standard I/O stream to output the
+ assembler code on. X is the RTL expression for the constant to
+ output, and MODE is the machine mode (in case X is a `const_int').
+ ALIGN is the required alignment for the value X; you should output
+ an assembler directive to force this much alignment.
+
+ The argument LABELNO is a number to use in an internal label for
+ the address of this pool entry. The definition of this macro is
+ responsible for outputting the label definition at the proper
+ place. Here is how to do this:
+
+ ASM_OUTPUT_INTERNAL_LABEL (FILE, "LC", LABELNO);
+
+ When you output a pool entry specially, you should end with a
+ `goto' to the label JUMPTO. This will prevent the same pool entry
+ from being output a second time in the usual manner.
+
+ You need not define this macro if it would do nothing.
+
+`CONSTANT_AFTER_FUNCTION_P (EXP)'
+ Define this macro as a C expression which is nonzero if the
+ constant EXP, of type `tree', should be output after the code for a
+ function. The compiler will normally output all constants before
+ the function; you need not define this macro if this is OK.
+
+`ASM_OUTPUT_POOL_EPILOGUE (FILE FUNNAME FUNDECL SIZE)'
+ A C statement to output assembler commands to at the end of the
+ constant pool for a function. FUNNAME is a string giving the name
+ of the function. Should the return type of the function be
+ required, you can obtain it via FUNDECL. SIZE is the size, in
+ bytes, of the constant pool that GCC wrote immediately before this
+ call.
+
+ If no constant-pool epilogue is required, the usual case, you need
+ not define this macro.
+
+`IS_ASM_LOGICAL_LINE_SEPARATOR (C)'
+ Define this macro as a C expression which is nonzero if C is used
+ as a logical line separator by the assembler.
+
+ If you do not define this macro, the default is that only the
+ character `;' is treated as a logical line separator.
+
+ -- Target Hook: const char * TARGET_ASM_OPEN_PAREN
+ -- Target Hook: const char * TARGET_ASM_CLOSE_PAREN
+ These target hooks are C string constants, describing the syntax
+ in the assembler for grouping arithmetic expressions. If not
+ overridden, they default to normal parentheses, which is correct
+ for most assemblers.
+
+ These macros are provided by `real.h' for writing the definitions of
+`ASM_OUTPUT_DOUBLE' and the like:
+
+`REAL_VALUE_TO_TARGET_SINGLE (X, L)'
+`REAL_VALUE_TO_TARGET_DOUBLE (X, L)'
+`REAL_VALUE_TO_TARGET_LONG_DOUBLE (X, L)'
+ These translate X, of type `REAL_VALUE_TYPE', to the target's
+ floating point representation, and store its bit pattern in the
+ array of `long int' whose address is L. The number of elements in
+ the output array is determined by the size of the desired target
+ floating point data type: 32 bits of it go in each `long int' array
+ element. Each array element holds 32 bits of the result, even if
+ `long int' is wider than 32 bits on the host machine.
+
+ The array element values are designed so that you can print them
+ out using `fprintf' in the order they should appear in the target
+ machine's memory.
+
+`REAL_VALUE_TO_DECIMAL (X, FORMAT, STRING)'
+ This macro converts X, of type `REAL_VALUE_TYPE', to a decimal
+ number and stores it as a string into STRING. You must pass, as
+ STRING, the address of a long enough block of space to hold the
+ result.
+
+ The argument FORMAT is a `printf'-specification that serves as a
+ suggestion for how to format the output string.
+
+\1f
+File: gccint.info, Node: Uninitialized Data, Next: Label Output, Prev: Data Output, Up: Assembler Format
+
+10.20.3 Output of Uninitialized Variables
+-----------------------------------------
+
+Each of the macros in this section is used to do the whole job of
+outputting a single uninitialized variable.
+
+`ASM_OUTPUT_COMMON (STREAM, NAME, SIZE, ROUNDED)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM the assembler definition of a common-label named NAME whose
+ size is SIZE bytes. The variable ROUNDED is the size rounded up
+ to whatever alignment the caller wants.
+
+ Use the expression `assemble_name (STREAM, NAME)' to output the
+ name itself; before and after that, output the additional
+ assembler syntax for defining the name, and a newline.
+
+ This macro controls how the assembler definitions of uninitialized
+ common global variables are output.
+
+`ASM_OUTPUT_ALIGNED_COMMON (STREAM, NAME, SIZE, ALIGNMENT)'
+ Like `ASM_OUTPUT_COMMON' except takes the required alignment as a
+ separate, explicit argument. If you define this macro, it is used
+ in place of `ASM_OUTPUT_COMMON', and gives you more flexibility in
+ handling the required alignment of the variable. The alignment is
+ specified as the number of bits.
+
+`ASM_OUTPUT_ALIGNED_DECL_COMMON (STREAM, DECL, NAME, SIZE, ALIGNMENT)'
+ Like `ASM_OUTPUT_ALIGNED_COMMON' except that DECL of the variable
+ to be output, if there is one, or `NULL_TREE' if there is no
+ corresponding variable. If you define this macro, GCC will use it
+ in place of both `ASM_OUTPUT_COMMON' and
+ `ASM_OUTPUT_ALIGNED_COMMON'. Define this macro when you need to
+ see the variable's decl in order to chose what to output.
+
+`ASM_OUTPUT_SHARED_COMMON (STREAM, NAME, SIZE, ROUNDED)'
+ If defined, it is similar to `ASM_OUTPUT_COMMON', except that it
+ is used when NAME is shared. If not defined, `ASM_OUTPUT_COMMON'
+ will be used.
+
+`ASM_OUTPUT_BSS (STREAM, DECL, NAME, SIZE, ROUNDED)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM the assembler definition of uninitialized global DECL named
+ NAME whose size is SIZE bytes. The variable ROUNDED is the size
+ rounded up to whatever alignment the caller wants.
+
+ Try to use function `asm_output_bss' defined in `varasm.c' when
+ defining this macro. If unable, use the expression `assemble_name
+ (STREAM, NAME)' to output the name itself; before and after that,
+ output the additional assembler syntax for defining the name, and
+ a newline.
+
+ This macro controls how the assembler definitions of uninitialized
+ global variables are output. This macro exists to properly
+ support languages like C++ which do not have `common' data.
+ However, this macro currently is not defined for all targets. If
+ this macro and `ASM_OUTPUT_ALIGNED_BSS' are not defined then
+ `ASM_OUTPUT_COMMON' or `ASM_OUTPUT_ALIGNED_COMMON' or
+ `ASM_OUTPUT_ALIGNED_DECL_COMMON' is used.
+
+`ASM_OUTPUT_ALIGNED_BSS (STREAM, DECL, NAME, SIZE, ALIGNMENT)'
+ Like `ASM_OUTPUT_BSS' except takes the required alignment as a
+ separate, explicit argument. If you define this macro, it is used
+ in place of `ASM_OUTPUT_BSS', and gives you more flexibility in
+ handling the required alignment of the variable. The alignment is
+ specified as the number of bits.
+
+ Try to use function `asm_output_aligned_bss' defined in file
+ `varasm.c' when defining this macro.
+
+`ASM_OUTPUT_SHARED_BSS (STREAM, DECL, NAME, SIZE, ROUNDED)'
+ If defined, it is similar to `ASM_OUTPUT_BSS', except that it is
+ used when NAME is shared. If not defined, `ASM_OUTPUT_BSS' will
+ be used.
+
+`ASM_OUTPUT_LOCAL (STREAM, NAME, SIZE, ROUNDED)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM the assembler definition of a local-common-label named NAME
+ whose size is SIZE bytes. The variable ROUNDED is the size
+ rounded up to whatever alignment the caller wants.
+
+ Use the expression `assemble_name (STREAM, NAME)' to output the
+ name itself; before and after that, output the additional
+ assembler syntax for defining the name, and a newline.
+
+ This macro controls how the assembler definitions of uninitialized
+ static variables are output.
+
+`ASM_OUTPUT_ALIGNED_LOCAL (STREAM, NAME, SIZE, ALIGNMENT)'
+ Like `ASM_OUTPUT_LOCAL' except takes the required alignment as a
+ separate, explicit argument. If you define this macro, it is used
+ in place of `ASM_OUTPUT_LOCAL', and gives you more flexibility in
+ handling the required alignment of the variable. The alignment is
+ specified as the number of bits.
+
+`ASM_OUTPUT_ALIGNED_DECL_LOCAL (STREAM, DECL, NAME, SIZE, ALIGNMENT)'
+ Like `ASM_OUTPUT_ALIGNED_DECL' except that DECL of the variable to
+ be output, if there is one, or `NULL_TREE' if there is no
+ corresponding variable. If you define this macro, GCC will use it
+ in place of both `ASM_OUTPUT_DECL' and `ASM_OUTPUT_ALIGNED_DECL'.
+ Define this macro when you need to see the variable's decl in
+ order to chose what to output.
+
+`ASM_OUTPUT_SHARED_LOCAL (STREAM, NAME, SIZE, ROUNDED)'
+ If defined, it is similar to `ASM_OUTPUT_LOCAL', except that it is
+ used when NAME is shared. If not defined, `ASM_OUTPUT_LOCAL' will
+ be used.
+
+\1f
+File: gccint.info, Node: Label Output, Next: Initialization, Prev: Uninitialized Data, Up: Assembler Format
+
+10.20.4 Output and Generation of Labels
+---------------------------------------
+
+This is about outputting labels.
+
+`ASM_OUTPUT_LABEL (STREAM, NAME)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM the assembler definition of a label named NAME. Use the
+ expression `assemble_name (STREAM, NAME)' to output the name
+ itself; before and after that, output the additional assembler
+ syntax for defining the name, and a newline.
+
+`ASM_DECLARE_FUNCTION_NAME (STREAM, NAME, DECL)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM any text necessary for declaring the name NAME of a
+ function which is being defined. This macro is responsible for
+ outputting the label definition (perhaps using
+ `ASM_OUTPUT_LABEL'). The argument DECL is the `FUNCTION_DECL'
+ tree node representing the function.
+
+ If this macro is not defined, then the function name is defined in
+ the usual manner as a label (by means of `ASM_OUTPUT_LABEL').
+
+`ASM_DECLARE_FUNCTION_SIZE (STREAM, NAME, DECL)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM any text necessary for declaring the size of a function
+ which is being defined. The argument NAME is the name of the
+ function. The argument DECL is the `FUNCTION_DECL' tree node
+ representing the function.
+
+ If this macro is not defined, then the function size is not
+ defined.
+
+`ASM_DECLARE_OBJECT_NAME (STREAM, NAME, DECL)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM any text necessary for declaring the name NAME of an
+ initialized variable which is being defined. This macro must
+ output the label definition (perhaps using `ASM_OUTPUT_LABEL').
+ The argument DECL is the `VAR_DECL' tree node representing the
+ variable.
+
+ If this macro is not defined, then the variable name is defined in
+ the usual manner as a label (by means of `ASM_OUTPUT_LABEL').
+
+`ASM_DECLARE_REGISTER_GLOBAL (STREAM, DECL, REGNO, NAME)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM any text necessary for claiming a register REGNO for a
+ global variable DECL with name NAME.
+
+ If you don't define this macro, that is equivalent to defining it
+ to do nothing.
+
+`ASM_FINISH_DECLARE_OBJECT (STREAM, DECL, TOPLEVEL, ATEND)'
+ A C statement (sans semicolon) to finish up declaring a variable
+ name once the compiler has processed its initializer fully and
+ thus has had a chance to determine the size of an array when
+ controlled by an initializer. This is used on systems where it's
+ necessary to declare something about the size of the object.
+
+ If you don't define this macro, that is equivalent to defining it
+ to do nothing.
+
+`ASM_GLOBALIZE_LABEL (STREAM, NAME)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM some commands that will make the label NAME global; that
+ is, available for reference from other files. Use the expression
+ `assemble_name (STREAM, NAME)' to output the name itself; before
+ and after that, output the additional assembler syntax for making
+ that name global, and a newline.
+
+`ASM_WEAKEN_LABEL (STREAM, NAME)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM some commands that will make the label NAME weak; that is,
+ available for reference from other files but only used if no other
+ definition is available. Use the expression `assemble_name
+ (STREAM, NAME)' to output the name itself; before and after that,
+ output the additional assembler syntax for making that name weak,
+ and a newline.
+
+ If you don't define this macro or `ASM_WEAKEN_DECL', GCC will not
+ support weak symbols and you should not define the `SUPPORTS_WEAK'
+ macro.
+
+`ASM_WEAKEN_DECL (STREAM, DECL, NAME, VALUE)'
+ Combines (and replaces) the function of `ASM_WEAKEN_LABEL' and
+ `ASM_OUTPUT_WEAK_ALIAS', allowing access to the associated function
+ or variable decl. If VALUE is not `NULL', this C statement should
+ output to the stdio stream STREAM assembler code which defines
+ (equates) the weak symbol NAME to have the value VALUE. If VALUE
+ is `NULL', it should output commands to make NAME weak.
+
+`SUPPORTS_WEAK'
+ A C expression which evaluates to true if the target supports weak
+ symbols.
+
+ If you don't define this macro, `defaults.h' provides a default
+ definition. If either `ASM_WEAKEN_LABEL' or `ASM_WEAKEN_DECL' is
+ defined, the default definition is `1'; otherwise, it is `0'.
+ Define this macro if you want to control weak symbol support with
+ a compiler flag such as `-melf'.
+
+`MAKE_DECL_ONE_ONLY'
+ A C statement (sans semicolon) to mark DECL to be emitted as a
+ public symbol such that extra copies in multiple translation units
+ will be discarded by the linker. Define this macro if your object
+ file format provides support for this concept, such as the `COMDAT'
+ section flags in the Microsoft Windows PE/COFF format, and this
+ support requires changes to DECL, such as putting it in a separate
+ section.
+
+`SUPPORTS_ONE_ONLY'
+ A C expression which evaluates to true if the target supports
+ one-only semantics.
+
+ If you don't define this macro, `varasm.c' provides a default
+ definition. If `MAKE_DECL_ONE_ONLY' is defined, the default
+ definition is `1'; otherwise, it is `0'. Define this macro if you
+ want to control one-only symbol support with a compiler flag, or if
+ setting the `DECL_ONE_ONLY' flag is enough to mark a declaration to
+ be emitted as one-only.
+
+`ASM_OUTPUT_EXTERNAL (STREAM, DECL, NAME)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM any text necessary for declaring the name of an external
+ symbol named NAME which is referenced in this compilation but not
+ defined. The value of DECL is the tree node for the declaration.
+
+ This macro need not be defined if it does not need to output
+ anything. The GNU assembler and most Unix assemblers don't
+ require anything.
+
+`ASM_OUTPUT_EXTERNAL_LIBCALL (STREAM, SYMREF)'
+ A C statement (sans semicolon) to output on STREAM an assembler
+ pseudo-op to declare a library function name external. The name
+ of the library function is given by SYMREF, which has type `rtx'
+ and is a `symbol_ref'.
+
+ This macro need not be defined if it does not need to output
+ anything. The GNU assembler and most Unix assemblers don't
+ require anything.
+
+`ASM_OUTPUT_LABELREF (STREAM, NAME)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM a reference in assembler syntax to a label named NAME.
+ This should add `_' to the front of the name, if that is customary
+ on your operating system, as it is in most Berkeley Unix systems.
+ This macro is used in `assemble_name'.
+
+`ASM_OUTPUT_SYMBOL_REF (STREAM, SYM)'
+ A C statement (sans semicolon) to output a reference to
+ `SYMBOL_REF' SYM. If not defined, `assemble_name' will be used to
+ output the name of the symbol. This macro may be used to modify
+ the way a symbol is referenced depending on information encoded by
+ `ENCODE_SECTION_INFO'.
+
+`ASM_OUTPUT_LABEL_REF (STREAM, BUF)'
+ A C statement (sans semicolon) to output a reference to BUF, the
+ result of ASM_GENERATE_INTERNAL_LABEL. If not defined,
+ `assemble_name' will be used to output the name of the symbol.
+ This macro is not used by `output_asm_label', or the `%l'
+ specifier that calls it; the intention is that this macro should
+ be set when it is necessary to output a label differently when its
+ address is being taken.
+
+`ASM_OUTPUT_INTERNAL_LABEL (STREAM, PREFIX, NUM)'
+ A C statement to output to the stdio stream STREAM a label whose
+ name is made from the string PREFIX and the number NUM.
+
+ It is absolutely essential that these labels be distinct from the
+ labels used for user-level functions and variables. Otherwise,
+ certain programs will have name conflicts with internal labels.
+
+ It is desirable to exclude internal labels from the symbol table
+ of the object file. Most assemblers have a naming convention for
+ labels that should be excluded; on many systems, the letter `L' at
+ the beginning of a label has this effect. You should find out what
+ convention your system uses, and follow it.
+
+ The usual definition of this macro is as follows:
+
+ fprintf (STREAM, "L%s%d:\n", PREFIX, NUM)
+
+`ASM_OUTPUT_DEBUG_LABEL (STREAM, PREFIX, NUM)'
+ A C statement to output to the stdio stream STREAM a debug info
+ label whose name is made from the string PREFIX and the number
+ NUM. This is useful for VLIW targets, where debug info labels may
+ need to be treated differently than branch target labels. On some
+ systems, branch target labels must be at the beginning of
+ instruction bundles, but debug info labels can occur in the middle
+ of instruction bundles.
+
+ If this macro is not defined, then `ASM_OUTPUT_INTERNAL_LABEL'
+ will be used.
+
+`ASM_OUTPUT_ALTERNATE_LABEL_NAME (STREAM, STRING)'
+ A C statement to output to the stdio stream STREAM the string
+ STRING.
+
+ The default definition of this macro is as follows:
+
+ fprintf (STREAM, "%s:\n", LABEL_ALTERNATE_NAME (INSN))
+
+`ASM_GENERATE_INTERNAL_LABEL (STRING, PREFIX, NUM)'
+ A C statement to store into the string STRING a label whose name
+ is made from the string PREFIX and the number NUM.
+
+ This string, when output subsequently by `assemble_name', should
+ produce the output that `ASM_OUTPUT_INTERNAL_LABEL' would produce
+ with the same PREFIX and NUM.
+
+ If the string begins with `*', then `assemble_name' will output
+ the rest of the string unchanged. It is often convenient for
+ `ASM_GENERATE_INTERNAL_LABEL' to use `*' in this way. If the
+ string doesn't start with `*', then `ASM_OUTPUT_LABELREF' gets to
+ output the string, and may change it. (Of course,
+ `ASM_OUTPUT_LABELREF' is also part of your machine description, so
+ you should know what it does on your machine.)
+
+`ASM_FORMAT_PRIVATE_NAME (OUTVAR, NAME, NUMBER)'
+ A C expression to assign to OUTVAR (which is a variable of type
+ `char *') a newly allocated string made from the string NAME and
+ the number NUMBER, with some suitable punctuation added. Use
+ `alloca' to get space for the string.
+
+ The string will be used as an argument to `ASM_OUTPUT_LABELREF' to
+ produce an assembler label for an internal static variable whose
+ name is NAME. Therefore, the string must be such as to result in
+ valid assembler code. The argument NUMBER is different each time
+ this macro is executed; it prevents conflicts between
+ similarly-named internal static variables in different scopes.
+
+ Ideally this string should not be a valid C identifier, to prevent
+ any conflict with the user's own symbols. Most assemblers allow
+ periods or percent signs in assembler symbols; putting at least
+ one of these between the name and the number will suffice.
+
+`ASM_OUTPUT_DEF (STREAM, NAME, VALUE)'
+ A C statement to output to the stdio stream STREAM assembler code
+ which defines (equates) the symbol NAME to have the value VALUE.
+
+ If `SET_ASM_OP' is defined, a default definition is provided which
+ is correct for most systems.
+
+`ASM_OUTPUT_DEF_FROM_DECLS (STREAM, DECL_OF_NAME, DECL_OF_VALUE)'
+ A C statement to output to the stdio stream STREAM assembler code
+ which defines (equates) the symbol whose tree node is DECL_OF_NAME
+ to have the value of the tree node DECL_OF_VALUE. This macro will
+ be used in preference to `ASM_OUTPUT_DEF' if it is defined and if
+ the tree nodes are available.
+
+`ASM_OUTPUT_DEFINE_LABEL_DIFFERENCE_SYMBOL (STREAM, SYMBOL, HIGH, LOW)'
+ A C statement to output to the stdio stream STREAM assembler code
+ which defines (equates) the symbol SYMBOL to have a value equal to
+ the difference of the two symbols HIGH and LOW, i.e. HIGH minus
+ LOW. GCC guarantees that the symbols HIGH and LOW are already
+ known by the assembler so that the difference resolves into a
+ constant.
+
+ If `SET_ASM_OP' is defined, a default definition is provided which
+ is correct for most systems.
+
+`ASM_OUTPUT_WEAK_ALIAS (STREAM, NAME, VALUE)'
+ A C statement to output to the stdio stream STREAM assembler code
+ which defines (equates) the weak symbol NAME to have the value
+ VALUE. If VALUE is `NULL', it defines NAME as an undefined weak
+ symbol.
+
+ Define this macro if the target only supports weak aliases; define
+ `ASM_OUTPUT_DEF' instead if possible.
+
+`OBJC_GEN_METHOD_LABEL (BUF, IS_INST, CLASS_NAME, CAT_NAME, SEL_NAME)'
+ Define this macro to override the default assembler names used for
+ Objective-C methods.
+
+ The default name is a unique method number followed by the name of
+ the class (e.g. `_1_Foo'). For methods in categories, the name of
+ the category is also included in the assembler name (e.g.
+ `_1_Foo_Bar').
+
+ These names are safe on most systems, but make debugging difficult
+ since the method's selector is not present in the name.
+ Therefore, particular systems define other ways of computing names.
+
+ BUF is an expression of type `char *' which gives you a buffer in
+ which to store the name; its length is as long as CLASS_NAME,
+ CAT_NAME and SEL_NAME put together, plus 50 characters extra.
+
+ The argument IS_INST specifies whether the method is an instance
+ method or a class method; CLASS_NAME is the name of the class;
+ CAT_NAME is the name of the category (or `NULL' if the method is
+ not in a category); and SEL_NAME is the name of the selector.
+
+ On systems where the assembler can handle quoted names, you can
+ use this macro to provide more human-readable names.
+
+`ASM_DECLARE_CLASS_REFERENCE (STREAM, NAME)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM commands to declare that the label NAME is an Objective-C
+ class reference. This is only needed for targets whose linkers
+ have special support for NeXT-style runtimes.
+
+`ASM_DECLARE_UNRESOLVED_REFERENCE (STREAM, NAME)'
+ A C statement (sans semicolon) to output to the stdio stream
+ STREAM commands to declare that the label NAME is an unresolved
+ Objective-C class reference. This is only needed for targets
+ whose linkers have special support for NeXT-style runtimes.
+
+\1f
+File: gccint.info, Node: Initialization, Next: Macros for Initialization, Prev: Label Output, Up: Assembler Format
+
+10.20.5 How Initialization Functions Are Handled
+------------------------------------------------
+
+The compiled code for certain languages includes "constructors" (also
+called "initialization routines")--functions to initialize data in the
+program when the program is started. These functions need to be called
+before the program is "started"--that is to say, before `main' is
+called.
+
+ Compiling some languages generates "destructors" (also called
+"termination routines") that should be called when the program
+terminates.
+
+ To make the initialization and termination functions work, the
+compiler must output something in the assembler code to cause those
+functions to be called at the appropriate time. When you port the
+compiler to a new system, you need to specify how to do this.
+
+ There are two major ways that GCC currently supports the execution of
+initialization and termination functions. Each way has two variants.
+Much of the structure is common to all four variations.
+
+ The linker must build two lists of these functions--a list of
+initialization functions, called `__CTOR_LIST__', and a list of
+termination functions, called `__DTOR_LIST__'.
+
+ Each list always begins with an ignored function pointer (which may
+hold 0, -1, or a count of the function pointers after it, depending on
+the environment). This is followed by a series of zero or more function
+pointers to constructors (or destructors), followed by a function
+pointer containing zero.
+
+ Depending on the operating system and its executable file format,
+either `crtstuff.c' or `libgcc2.c' traverses these lists at startup
+time and exit time. Constructors are called in reverse order of the
+list; destructors in forward order.
+
+ The best way to handle static constructors works only for object file
+formats which provide arbitrarily-named sections. A section is set
+aside for a list of constructors, and another for a list of destructors.
+Traditionally these are called `.ctors' and `.dtors'. Each object file
+that defines an initialization function also puts a word in the
+constructor section to point to that function. The linker accumulates
+all these words into one contiguous `.ctors' section. Termination
+functions are handled similarly.
+
+ This method will be chosen as the default by `target-def.h' if
+`TARGET_ASM_NAMED_SECTION' is defined. A target that does not support
+arbitrary sections, but does support special designated constructor and
+destructor sections may define `CTORS_SECTION_ASM_OP' and
+`DTORS_SECTION_ASM_OP' to achieve the same effect.
+
+ When arbitrary sections are available, there are two variants,
+depending upon how the code in `crtstuff.c' is called. On systems that
+support a ".init" section which is executed at program startup, parts
+of `crtstuff.c' are compiled into that section. The program is linked
+by the `gcc' driver like this:
+
+ ld -o OUTPUT_FILE crti.o crtbegin.o ... -lgcc crtend.o crtn.o
+
+ The prologue of a function (`__init') appears in the `.init' section
+of `crti.o'; the epilogue appears in `crtn.o'. Likewise for the
+function `__fini' in the ".fini" section. Normally these files are
+provided by the operating system or by the GNU C library, but are
+provided by GCC for a few targets.
+
+ The objects `crtbegin.o' and `crtend.o' are (for most targets)
+compiled from `crtstuff.c'. They contain, among other things, code
+fragments within the `.init' and `.fini' sections that branch to
+routines in the `.text' section. The linker will pull all parts of a
+section together, which results in a complete `__init' function that
+invokes the routines we need at startup.
+
+ To use this variant, you must define the `INIT_SECTION_ASM_OP' macro
+properly.
+
+ If no init section is available, when GCC compiles any function
+called `main' (or more accurately, any function designated as a program
+entry point by the language front end calling `expand_main_function'),
+it inserts a procedure call to `__main' as the first executable code
+after the function prologue. The `__main' function is defined in
+`libgcc2.c' and runs the global constructors.
+
+ In file formats that don't support arbitrary sections, there are
+again two variants. In the simplest variant, the GNU linker (GNU `ld')
+and an `a.out' format must be used. In this case,
+`TARGET_ASM_CONSTRUCTOR' is defined to produce a `.stabs' entry of type
+`N_SETT', referencing the name `__CTOR_LIST__', and with the address of
+the void function containing the initialization code as its value. The
+GNU linker recognizes this as a request to add the value to a "set";
+the values are accumulated, and are eventually placed in the executable
+as a vector in the format described above, with a leading (ignored)
+count and a trailing zero element. `TARGET_ASM_DESTRUCTOR' is handled
+similarly. Since no init section is available, the absence of
+`INIT_SECTION_ASM_OP' causes the compilation of `main' to call `__main'
+as above, starting the initialization process.
+
+ The last variant uses neither arbitrary sections nor the GNU linker.
+This is preferable when you want to do dynamic linking and when using
+file formats which the GNU linker does not support, such as `ECOFF'. In
+this case, `TARGET_HAVE_CTORS_DTORS' is false, initialization and
+termination functions are recognized simply by their names. This
+requires an extra program in the linkage step, called `collect2'. This
+program pretends to be the linker, for use with GCC; it does its job by
+running the ordinary linker, but also arranges to include the vectors of
+initialization and termination functions. These functions are called
+via `__main' as described above. In order to use this method,
+`use_collect2' must be defined in the target in `config.gcc'.
+
+ The following section describes the specific macros that control and
+customize the handling of initialization and termination functions.
+
+\1f
+File: gccint.info, Node: Macros for Initialization, Next: Instruction Output, Prev: Initialization, Up: Assembler Format
+
+10.20.6 Macros Controlling Initialization Routines
+--------------------------------------------------
+
+Here are the macros that control how the compiler handles initialization
+and termination functions:
+
+`INIT_SECTION_ASM_OP'
+ If defined, a C string constant, including spacing, for the
+ assembler operation to identify the following data as
+ initialization code. If not defined, GCC will assume such a
+ section does not exist. When you are using special sections for
+ initialization and termination functions, this macro also controls
+ how `crtstuff.c' and `libgcc2.c' arrange to run the initialization
+ functions.
+
+`HAS_INIT_SECTION'
+ If defined, `main' will not call `__main' as described above.
+ This macro should be defined for systems that control start-up code
+ on a symbol-by-symbol basis, such as OSF/1, and should not be
+ defined explicitly for systems that support `INIT_SECTION_ASM_OP'.
+
+`LD_INIT_SWITCH'
+ If defined, a C string constant for a switch that tells the linker
+ that the following symbol is an initialization routine.
+
+`LD_FINI_SWITCH'
+ If defined, a C string constant for a switch that tells the linker
+ that the following symbol is a finalization routine.
+
+`COLLECT_SHARED_INIT_FUNC (STREAM, FUNC)'
+ If defined, a C statement that will write a function that can be
+ automatically called when a shared library is loaded. The function
+ should call FUNC, which takes no arguments. If not defined, and
+ the object format requires an explicit initialization function,
+ then a function called `_GLOBAL__DI' will be generated.
+
+ This function and the following one are used by collect2 when
+ linking a shared library that needs constructors or destructors,
+ or has DWARF2 exception tables embedded in the code.
+
+`COLLECT_SHARED_FINI_FUNC (STREAM, FUNC)'
+ If defined, a C statement that will write a function that can be
+ automatically called when a shared library is unloaded. The
+ function should call FUNC, which takes no arguments. If not
+ defined, and the object format requires an explicit finalization
+ function, then a function called `_GLOBAL__DD' will be generated.
+
+`INVOKE__main'
+ If defined, `main' will call `__main' despite the presence of
+ `INIT_SECTION_ASM_OP'. This macro should be defined for systems
+ where the init section is not actually run automatically, but is
+ still useful for collecting the lists of constructors and
+ destructors.
+
+`SUPPORTS_INIT_PRIORITY'
+ If nonzero, the C++ `init_priority' attribute is supported and the
+ compiler should emit instructions to control the order of
+ initialization of objects. If zero, the compiler will issue an
+ error message upon encountering an `init_priority' attribute.
+
+ -- Target Hook: bool TARGET_HAVE_CTORS_DTORS
+ This value is true if the target supports some "native" method of
+ collecting constructors and destructors to be run at startup and
+ exit. It is false if we must use `collect2'.
+
+ -- Target Hook: void TARGET_ASM_CONSTRUCTOR (rtx SYMBOL, int PRIORITY)
+ If defined, a function that outputs assembler code to arrange to
+ call the function referenced by SYMBOL at initialization time.
+
+ Assume that SYMBOL is a `SYMBOL_REF' for a function taking no
+ arguments and with no return value. If the target supports
+ initialization priorities, PRIORITY is a value between 0 and
+ `MAX_INIT_PRIORITY'; otherwise it must be `DEFAULT_INIT_PRIORITY'.
+
+ If this macro is not defined by the target, a suitable default will
+ be chosen if (1) the target supports arbitrary section names, (2)
+ the target defines `CTORS_SECTION_ASM_OP', or (3) `USE_COLLECT2'
+ is not defined.
+
+ -- Target Hook: void TARGET_ASM_DESTRUCTOR (rtx SYMBOL, int PRIORITY)
+ This is like `TARGET_ASM_CONSTRUCTOR' but used for termination
+ functions rather than initialization functions.
+
+ If `TARGET_HAVE_CTORS_DTORS' is true, the initialization routine
+generated for the generated object file will have static linkage.
+
+ If your system uses `collect2' as the means of processing
+constructors, then that program normally uses `nm' to scan an object
+file for constructor functions to be called.
+
+ On certain kinds of systems, you can define these macros to make
+`collect2' work faster (and, in some cases, make it work at all):
+
+`OBJECT_FORMAT_COFF'
+ Define this macro if the system uses COFF (Common Object File
+ Format) object files, so that `collect2' can assume this format
+ and scan object files directly for dynamic constructor/destructor
+ functions.
+
+`OBJECT_FORMAT_ROSE'
+ Define this macro if the system uses ROSE format object files, so
+ that `collect2' can assume this format and scan object files
+ directly for dynamic constructor/destructor functions.
+
+ These macros are effective only in a native compiler; `collect2' as
+ part of a cross compiler always uses `nm' for the target machine.
+
+`REAL_NM_FILE_NAME'
+ Define this macro as a C string constant containing the file name
+ to use to execute `nm'. The default is to search the path
+ normally for `nm'.
+
+ If your system supports shared libraries and has a program to list
+ the dynamic dependencies of a given library or executable, you can
+ define these macros to enable support for running initialization
+ and termination functions in shared libraries:
+
+`LDD_SUFFIX'
+ Define this macro to a C string constant containing the name of
+ the program which lists dynamic dependencies, like `"ldd"' under
+ SunOS 4.
+
+`PARSE_LDD_OUTPUT (PTR)'
+ Define this macro to be C code that extracts filenames from the
+ output of the program denoted by `LDD_SUFFIX'. PTR is a variable
+ of type `char *' that points to the beginning of a line of output
+ from `LDD_SUFFIX'. If the line lists a dynamic dependency, the
+ code must advance PTR to the beginning of the filename on that
+ line. Otherwise, it must set PTR to `NULL'.
+
+\1f
+File: gccint.info, Node: Instruction Output, Next: Dispatch Tables, Prev: Macros for Initialization, Up: Assembler Format
+
+10.20.7 Output of Assembler Instructions
+----------------------------------------
+
+This describes assembler instruction output.
+
+`REGISTER_NAMES'
+ A C initializer containing the assembler's names for the machine
+ registers, each one as a C string constant. This is what
+ translates register numbers in the compiler into assembler
+ language.
+
+`ADDITIONAL_REGISTER_NAMES'
+ If defined, a C initializer for an array of structures containing
+ a name and a register number. This macro defines additional names
+ for hard registers, thus allowing the `asm' option in declarations
+ to refer to registers using alternate names.
+
+`ASM_OUTPUT_OPCODE (STREAM, PTR)'
+ Define this macro if you are using an unusual assembler that
+ requires different names for the machine instructions.
+
+ The definition is a C statement or statements which output an
+ assembler instruction opcode to the stdio stream STREAM. The
+ macro-operand PTR is a variable of type `char *' which points to
+ the opcode name in its "internal" form--the form that is written
+ in the machine description. The definition should output the
+ opcode name to STREAM, performing any translation you desire, and
+ increment the variable PTR to point at the end of the opcode so
+ that it will not be output twice.
+
+ In fact, your macro definition may process less than the entire
+ opcode name, or more than the opcode name; but if you want to
+ process text that includes `%'-sequences to substitute operands,
+ you must take care of the substitution yourself. Just be sure to
+ increment PTR over whatever text should not be output normally.
+
+ If you need to look at the operand values, they can be found as the
+ elements of `recog_data.operand'.
+
+ If the macro definition does nothing, the instruction is output in
+ the usual way.
+
+`FINAL_PRESCAN_INSN (INSN, OPVEC, NOPERANDS)'
+ If defined, a C statement to be executed just prior to the output
+ of assembler code for INSN, to modify the extracted operands so
+ they will be output differently.
+
+ Here the argument OPVEC is the vector containing the operands
+ extracted from INSN, and NOPERANDS is the number of elements of
+ the vector which contain meaningful data for this insn. The
+ contents of this vector are what will be used to convert the insn
+ template into assembler code, so you can change the assembler
+ output by changing the contents of the vector.
+
+ This macro is useful when various assembler syntaxes share a single
+ file of instruction patterns; by defining this macro differently,
+ you can cause a large class of instructions to be output
+ differently (such as with rearranged operands). Naturally,
+ variations in assembler syntax affecting individual insn patterns
+ ought to be handled by writing conditional output routines in
+ those patterns.
+
+ If this macro is not defined, it is equivalent to a null statement.
+
+`FINAL_PRESCAN_LABEL'
+ If defined, `FINAL_PRESCAN_INSN' will be called on each
+ `CODE_LABEL'. In that case, OPVEC will be a null pointer and
+ NOPERANDS will be zero.
+
+`PRINT_OPERAND (STREAM, X, CODE)'
+ A C compound statement to output to stdio stream STREAM the
+ assembler syntax for an instruction operand X. X is an RTL
+ expression.
+
+ CODE is a value that can be used to specify one of several ways of
+ printing the operand. It is used when identical operands must be
+ printed differently depending on the context. CODE comes from the
+ `%' specification that was used to request printing of the
+ operand. If the specification was just `%DIGIT' then CODE is 0;
+ if the specification was `%LTR DIGIT' then CODE is the ASCII code
+ for LTR.
+
+ If X is a register, this macro should print the register's name.
+ The names can be found in an array `reg_names' whose type is `char
+ *[]'. `reg_names' is initialized from `REGISTER_NAMES'.
+
+ When the machine description has a specification `%PUNCT' (a `%'
+ followed by a punctuation character), this macro is called with a
+ null pointer for X and the punctuation character for CODE.
+
+`PRINT_OPERAND_PUNCT_VALID_P (CODE)'
+ A C expression which evaluates to true if CODE is a valid
+ punctuation character for use in the `PRINT_OPERAND' macro. If
+ `PRINT_OPERAND_PUNCT_VALID_P' is not defined, it means that no
+ punctuation characters (except for the standard one, `%') are used
+ in this way.
+
+`PRINT_OPERAND_ADDRESS (STREAM, X)'
+ A C compound statement to output to stdio stream STREAM the
+ assembler syntax for an instruction operand that is a memory
+ reference whose address is X. X is an RTL expression.
+
+ On some machines, the syntax for a symbolic address depends on the
+ section that the address refers to. On these machines, define the
+ macro `ENCODE_SECTION_INFO' to store the information into the
+ `symbol_ref', and then check for it here. *Note Assembler
+ Format::.
+
+`DBR_OUTPUT_SEQEND(FILE)'
+ A C statement, to be executed after all slot-filler instructions
+ have been output. If necessary, call `dbr_sequence_length' to
+ determine the number of slots filled in a sequence (zero if not
+ currently outputting a sequence), to decide how many no-ops to
+ output, or whatever.
+
+ Don't define this macro if it has nothing to do, but it is helpful
+ in reading assembly output if the extent of the delay sequence is
+ made explicit (e.g. with white space).
+
+ Note that output routines for instructions with delay slots must be
+ prepared to deal with not being output as part of a sequence (i.e.
+ when the scheduling pass is not run, or when no slot fillers could
+ be found.) The variable `final_sequence' is null when not
+ processing a sequence, otherwise it contains the `sequence' rtx
+ being output.
+
+`REGISTER_PREFIX'
+`LOCAL_LABEL_PREFIX'
+`USER_LABEL_PREFIX'
+`IMMEDIATE_PREFIX'
+ If defined, C string expressions to be used for the `%R', `%L',
+ `%U', and `%I' options of `asm_fprintf' (see `final.c'). These
+ are useful when a single `md' file must support multiple assembler
+ formats. In that case, the various `tm.h' files can define these
+ macros differently.
+
+`ASM_FPRINTF_EXTENSIONS(FILE, ARGPTR, FORMAT)'
+ If defined this macro should expand to a series of `case'
+ statements which will be parsed inside the `switch' statement of
+ the `asm_fprintf' function. This allows targets to define extra
+ printf formats which may useful when generating their assembler
+ statements. Note that upper case letters are reserved for future
+ generic extensions to asm_fprintf, and so are not available to
+ target specific code. The output file is given by the parameter
+ FILE. The varargs input pointer is ARGPTR and the rest of the
+ format string, starting the character after the one that is being
+ switched upon, is pointed to by FORMAT.
+
+`ASSEMBLER_DIALECT'
+ If your target supports multiple dialects of assembler language
+ (such as different opcodes), define this macro as a C expression
+ that gives the numeric index of the assembler language dialect to
+ use, with zero as the first variant.
+
+ If this macro is defined, you may use constructs of the form
+ `{option0|option1|option2...}'
+ in the output templates of patterns (*note Output Template::) or
+ in the first argument of `asm_fprintf'. This construct outputs
+ `option0', `option1', `option2', etc., if the value of
+ `ASSEMBLER_DIALECT' is zero, one, two, etc. Any special characters
+ within these strings retain their usual meaning. If there are
+ fewer alternatives within the braces than the value of
+ `ASSEMBLER_DIALECT', the construct outputs nothing.
+
+ If you do not define this macro, the characters `{', `|' and `}'
+ do not have any special meaning when used in templates or operands
+ to `asm_fprintf'.
+
+ Define the macros `REGISTER_PREFIX', `LOCAL_LABEL_PREFIX',
+ `USER_LABEL_PREFIX' and `IMMEDIATE_PREFIX' if you can express the
+ variations in assembler language syntax with that mechanism.
+ Define `ASSEMBLER_DIALECT' and use the `{option0|option1}' syntax
+ if the syntax variant are larger and involve such things as
+ different opcodes or operand order.
+
+`ASM_OUTPUT_REG_PUSH (STREAM, REGNO)'
+ A C expression to output to STREAM some assembler code which will
+ push hard register number REGNO onto the stack. The code need not
+ be optimal, since this macro is used only when profiling.
+
+`ASM_OUTPUT_REG_POP (STREAM, REGNO)'
+ A C expression to output to STREAM some assembler code which will
+ pop hard register number REGNO off of the stack. The code need
+ not be optimal, since this macro is used only when profiling.
+
+\1f
+File: gccint.info, Node: Dispatch Tables, Next: Exception Region Output, Prev: Instruction Output, Up: Assembler Format
+
+10.20.8 Output of Dispatch Tables
+---------------------------------
+
+This concerns dispatch tables.
+
+`ASM_OUTPUT_ADDR_DIFF_ELT (STREAM, BODY, VALUE, REL)'
+ A C statement to output to the stdio stream STREAM an assembler
+ pseudo-instruction to generate a difference between two labels.
+ VALUE and REL are the numbers of two internal labels. The
+ definitions of these labels are output using
+ `ASM_OUTPUT_INTERNAL_LABEL', and they must be printed in the same
+ way here. For example,
+
+ fprintf (STREAM, "\t.word L%d-L%d\n",
+ VALUE, REL)
+
+ You must provide this macro on machines where the addresses in a
+ dispatch table are relative to the table's own address. If
+ defined, GCC will also use this macro on all machines when
+ producing PIC. BODY is the body of the `ADDR_DIFF_VEC'; it is
+ provided so that the mode and flags can be read.
+
+`ASM_OUTPUT_ADDR_VEC_ELT (STREAM, VALUE)'
+ This macro should be provided on machines where the addresses in a
+ dispatch table are absolute.
+
+ The definition should be a C statement to output to the stdio
+ stream STREAM an assembler pseudo-instruction to generate a
+ reference to a label. VALUE is the number of an internal label
+ whose definition is output using `ASM_OUTPUT_INTERNAL_LABEL'. For
+ example,
+
+ fprintf (STREAM, "\t.word L%d\n", VALUE)
+
+`ASM_OUTPUT_CASE_LABEL (STREAM, PREFIX, NUM, TABLE)'
+ Define this if the label before a jump-table needs to be output
+ specially. The first three arguments are the same as for
+ `ASM_OUTPUT_INTERNAL_LABEL'; the fourth argument is the jump-table
+ which follows (a `jump_insn' containing an `addr_vec' or
+ `addr_diff_vec').
+
+ This feature is used on system V to output a `swbeg' statement for
+ the table.
+
+ If this macro is not defined, these labels are output with
+ `ASM_OUTPUT_INTERNAL_LABEL'.
+
+`ASM_OUTPUT_CASE_END (STREAM, NUM, TABLE)'
+ Define this if something special must be output at the end of a
+ jump-table. The definition should be a C statement to be executed
+ after the assembler code for the table is written. It should write
+ the appropriate code to stdio stream STREAM. The argument TABLE
+ is the jump-table insn, and NUM is the label-number of the
+ preceding label.
+
+ If this macro is not defined, nothing special is output at the end
+ of the jump-table.
+
+\1f
+File: gccint.info, Node: Exception Region Output, Next: Alignment Output, Prev: Dispatch Tables, Up: Assembler Format
+
+10.20.9 Assembler Commands for Exception Regions
+------------------------------------------------
+
+This describes commands marking the start and the end of an exception
+region.
+
+`EH_FRAME_SECTION_NAME'
+ If defined, a C string constant for the name of the section
+ containing exception handling frame unwind information. If not
+ defined, GCC will provide a default definition if the target
+ supports named sections. `crtstuff.c' uses this macro to switch
+ to the appropriate section.
+
+ You should define this symbol if your target supports DWARF 2 frame
+ unwind information and the default definition does not work.
+
+`EH_FRAME_IN_DATA_SECTION'
+ If defined, DWARF 2 frame unwind information will be placed in the
+ data section even though the target supports named sections. This
+ might be necessary, for instance, if the system linker does garbage
+ collection and sections cannot be marked as not to be collected.
+
+ Do not define this macro unless `TARGET_ASM_NAMED_SECTION' is also
+ defined.
+
+`MASK_RETURN_ADDR'
+ An rtx used to mask the return address found via
+ `RETURN_ADDR_RTX', so that it does not contain any extraneous set
+ bits in it.
+
+`DWARF2_UNWIND_INFO'
+ Define this macro to 0 if your target supports DWARF 2 frame unwind
+ information, but it does not yet work with exception handling.
+ Otherwise, if your target supports this information (if it defines
+ `INCOMING_RETURN_ADDR_RTX' and either `UNALIGNED_INT_ASM_OP' or
+ `OBJECT_FORMAT_ELF'), GCC will provide a default definition of 1.
+
+ If this macro is defined to 1, the DWARF 2 unwinder will be the
+ default exception handling mechanism; otherwise,
+ `setjmp'/`longjmp' will be used by default.
+
+ If this macro is defined to anything, the DWARF 2 unwinder will be
+ used instead of inline unwinders and `__unwind_function' in the
+ non-`setjmp' case.
+
+`DWARF_CIE_DATA_ALIGNMENT'
+ This macro need only be defined if the target might save registers
+ in the function prologue at an offset to the stack pointer that is
+ not aligned to `UNITS_PER_WORD'. The definition should be the
+ negative minimum alignment if `STACK_GROWS_DOWNWARD' is defined,
+ and the positive minimum alignment otherwise. *Note SDB and
+ DWARF::. Only applicable if the target supports DWARF 2 frame
+ unwind information.
+
+
+ -- Target Hook: void TARGET_ASM_EXCEPTION_SECTION ()
+ If defined, a function that switches to the section in which the
+ main exception table is to be placed (*note Sections::). The
+ default is a function that switches to a section named
+ `.gcc_except_table' on machines that support named sections via
+ `TARGET_ASM_NAMED_SECTION', otherwise if `-fpic' or `-fPIC' is in
+ effect, the `data_section', otherwise the `readonly_data_section'.
+
+ -- Target Hook: void TARGET_ASM_EH_FRAME_SECTION ()
+ If defined, a function that switches to the section in which the
+ DWARF 2 frame unwind information to be placed (*note Sections::).
+ The default is a function that outputs a standard GAS section
+ directive, if `EH_FRAME_SECTION_NAME' is defined, or else a data
+ section directive followed by a synthetic label.
+
+\1f
+File: gccint.info, Node: Alignment Output, Prev: Exception Region Output, Up: Assembler Format
+
+10.20.10 Assembler Commands for Alignment
+-----------------------------------------
+
+This describes commands for alignment.
+
+`JUMP_ALIGN (LABEL)'
+ The alignment (log base 2) to put in front of LABEL, which is a
+ common destination of jumps and has no fallthru incoming edge.
+
+ This macro need not be defined if you don't want any special
+ alignment to be done at such a time. Most machine descriptions do
+ not currently define the macro.
+
+ Unless it's necessary to inspect the LABEL parameter, it is better
+ to set the variable ALIGN_JUMPS in the target's
+ `OVERRIDE_OPTIONS'. Otherwise, you should try to honor the user's
+ selection in ALIGN_JUMPS in a `JUMP_ALIGN' implementation.
+
+`LABEL_ALIGN_AFTER_BARRIER (LABEL)'
+ The alignment (log base 2) to put in front of LABEL, which follows
+ a `BARRIER'.
+
+ This macro need not be defined if you don't want any special
+ alignment to be done at such a time. Most machine descriptions do
+ not currently define the macro.
+
+`LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP'
+ The maximum number of bytes to skip when applying
+ `LABEL_ALIGN_AFTER_BARRIER'. This works only if
+ `ASM_OUTPUT_MAX_SKIP_ALIGN' is defined.
+
+`LOOP_ALIGN (LABEL)'
+ The alignment (log base 2) to put in front of LABEL, which follows
+ a `NOTE_INSN_LOOP_BEG' note.
+
+ This macro need not be defined if you don't want any special
+ alignment to be done at such a time. Most machine descriptions do
+ not currently define the macro.
+
+ Unless it's necessary to inspect the LABEL parameter, it is better
+ to set the variable `align_loops' in the target's
+ `OVERRIDE_OPTIONS'. Otherwise, you should try to honor the user's
+ selection in `align_loops' in a `LOOP_ALIGN' implementation.
+
+`LOOP_ALIGN_MAX_SKIP'
+ The maximum number of bytes to skip when applying `LOOP_ALIGN'.
+ This works only if `ASM_OUTPUT_MAX_SKIP_ALIGN' is defined.
+
+`LABEL_ALIGN (LABEL)'
+ The alignment (log base 2) to put in front of LABEL. If
+ `LABEL_ALIGN_AFTER_BARRIER' / `LOOP_ALIGN' specify a different
+ alignment, the maximum of the specified values is used.
+
+ Unless it's necessary to inspect the LABEL parameter, it is better
+ to set the variable `align_labels' in the target's
+ `OVERRIDE_OPTIONS'. Otherwise, you should try to honor the user's
+ selection in `align_labels' in a `LABEL_ALIGN' implementation.
+
+`LABEL_ALIGN_MAX_SKIP'
+ The maximum number of bytes to skip when applying `LABEL_ALIGN'.
+ This works only if `ASM_OUTPUT_MAX_SKIP_ALIGN' is defined.
+
+`ASM_OUTPUT_SKIP (STREAM, NBYTES)'
+ A C statement to output to the stdio stream STREAM an assembler
+ instruction to advance the location counter by NBYTES bytes.
+ Those bytes should be zero when loaded. NBYTES will be a C
+ expression of type `int'.
+
+`ASM_NO_SKIP_IN_TEXT'
+ Define this macro if `ASM_OUTPUT_SKIP' should not be used in the
+ text section because it fails to put zeros in the bytes that are
+ skipped. This is true on many Unix systems, where the pseudo-op
+ to skip bytes produces no-op instructions rather than zeros when
+ used in the text section.
+
+`ASM_OUTPUT_ALIGN (STREAM, POWER)'
+ A C statement to output to the stdio stream STREAM an assembler
+ command to advance the location counter to a multiple of 2 to the
+ POWER bytes. POWER will be a C expression of type `int'.
+
+`ASM_OUTPUT_MAX_SKIP_ALIGN (STREAM, POWER, MAX_SKIP)'
+ A C statement to output to the stdio stream STREAM an assembler
+ command to advance the location counter to a multiple of 2 to the
+ POWER bytes, but only if MAX_SKIP or fewer bytes are needed to
+ satisfy the alignment request. POWER and MAX_SKIP will be a C
+ expression of type `int'.
+
+\1f
+File: gccint.info, Node: Debugging Info, Next: Cross-compilation, Prev: Assembler Format, Up: Target Macros
+
+10.21 Controlling Debugging Information Format
+==============================================
+
+This describes how to specify debugging information.
* Menu:
-* Function Basics:: Function names, linkage, and so forth.
-* Function Bodies:: The statements that make up a function body.
+* All Debuggers:: Macros that affect all debugging formats uniformly.
+* DBX Options:: Macros enabling specific options in DBX format.
+* DBX Hooks:: Hook macros for varying DBX format.
+* File Names and DBX:: Macros controlling output of file names in DBX format.
+* SDB and DWARF:: Macros for SDB (COFF) and DWARF formats.
+* VMS Debug:: Macros for VMS debug format.
\1f
-File: gccint.info, Node: Function Basics, Next: Function Bodies, Up: Functions
+File: gccint.info, Node: All Debuggers, Next: DBX Options, Up: Debugging Info
+
+10.21.1 Macros Affecting All Debugging Formats
+----------------------------------------------
+
+These macros affect all debugging formats.
+
+`DBX_REGISTER_NUMBER (REGNO)'
+ A C expression that returns the DBX register number for the
+ compiler register number REGNO. In the default macro provided,
+ the value of this expression will be REGNO itself. But sometimes
+ there are some registers that the compiler knows about and DBX
+ does not, or vice versa. In such cases, some register may need to
+ have one number in the compiler and another for DBX.
+
+ If two registers have consecutive numbers inside GCC, and they can
+ be used as a pair to hold a multiword value, then they _must_ have
+ consecutive numbers after renumbering with `DBX_REGISTER_NUMBER'.
+ Otherwise, debuggers will be unable to access such a pair, because
+ they expect register pairs to be consecutive in their own
+ numbering scheme.
+
+ If you find yourself defining `DBX_REGISTER_NUMBER' in way that
+ does not preserve register pairs, then what you must do instead is
+ redefine the actual register numbering scheme.
+
+`DEBUGGER_AUTO_OFFSET (X)'
+ A C expression that returns the integer offset value for an
+ automatic variable having address X (an RTL expression). The
+ default computation assumes that X is based on the frame-pointer
+ and gives the offset from the frame-pointer. This is required for
+ targets that produce debugging output for DBX or COFF-style
+ debugging output for SDB and allow the frame-pointer to be
+ eliminated when the `-g' options is used.
+
+`DEBUGGER_ARG_OFFSET (OFFSET, X)'
+ A C expression that returns the integer offset value for an
+ argument having address X (an RTL expression). The nominal offset
+ is OFFSET.
+
+`PREFERRED_DEBUGGING_TYPE'
+ A C expression that returns the type of debugging output GCC should
+ produce when the user specifies just `-g'. Define this if you
+ have arranged for GCC to support more than one format of debugging
+ output. Currently, the allowable values are `DBX_DEBUG',
+ `SDB_DEBUG', `DWARF_DEBUG', `DWARF2_DEBUG', `XCOFF_DEBUG',
+ `VMS_DEBUG', and `VMS_AND_DWARF2_DEBUG'.
+
+ When the user specifies `-ggdb', GCC normally also uses the value
+ of this macro to select the debugging output format, but with two
+ exceptions. If `DWARF2_DEBUGGING_INFO' is defined and
+ `LINKER_DOES_NOT_WORK_WITH_DWARF2' is not defined, GCC uses the
+ value `DWARF2_DEBUG'. Otherwise, if `DBX_DEBUGGING_INFO' is
+ defined, GCC uses `DBX_DEBUG'.
+
+ The value of this macro only affects the default debugging output;
+ the user can always get a specific type of output by using
+ `-gstabs', `-gcoff', `-gdwarf-1', `-gdwarf-2', `-gxcoff', or
+ `-gvms'.
-Function Basics
----------------
+\1f
+File: gccint.info, Node: DBX Options, Next: DBX Hooks, Prev: All Debuggers, Up: Debugging Info
+
+10.21.2 Specific Options for DBX Output
+---------------------------------------
+
+These are specific options for DBX output.
+
+`DBX_DEBUGGING_INFO'
+ Define this macro if GCC should produce debugging output for DBX
+ in response to the `-g' option.
+
+`XCOFF_DEBUGGING_INFO'
+ Define this macro if GCC should produce XCOFF format debugging
+ output in response to the `-g' option. This is a variant of DBX
+ format.
+
+`DEFAULT_GDB_EXTENSIONS'
+ Define this macro to control whether GCC should by default generate
+ GDB's extended version of DBX debugging information (assuming
+ DBX-format debugging information is enabled at all). If you don't
+ define the macro, the default is 1: always generate the extended
+ information if there is any occasion to.
+
+`DEBUG_SYMS_TEXT'
+ Define this macro if all `.stabs' commands should be output while
+ in the text section.
+
+`ASM_STABS_OP'
+ A C string constant, including spacing, naming the assembler
+ pseudo op to use instead of `"\t.stabs\t"' to define an ordinary
+ debugging symbol. If you don't define this macro, `"\t.stabs\t"'
+ is used. This macro applies only to DBX debugging information
+ format.
+
+`ASM_STABD_OP'
+ A C string constant, including spacing, naming the assembler
+ pseudo op to use instead of `"\t.stabd\t"' to define a debugging
+ symbol whose value is the current location. If you don't define
+ this macro, `"\t.stabd\t"' is used. This macro applies only to
+ DBX debugging information format.
+
+`ASM_STABN_OP'
+ A C string constant, including spacing, naming the assembler
+ pseudo op to use instead of `"\t.stabn\t"' to define a debugging
+ symbol with no name. If you don't define this macro,
+ `"\t.stabn\t"' is used. This macro applies only to DBX debugging
+ information format.
+
+`DBX_NO_XREFS'
+ Define this macro if DBX on your system does not support the
+ construct `xsTAGNAME'. On some systems, this construct is used to
+ describe a forward reference to a structure named TAGNAME. On
+ other systems, this construct is not supported at all.
+
+`DBX_CONTIN_LENGTH'
+ A symbol name in DBX-format debugging information is normally
+ continued (split into two separate `.stabs' directives) when it
+ exceeds a certain length (by default, 80 characters). On some
+ operating systems, DBX requires this splitting; on others,
+ splitting must not be done. You can inhibit splitting by defining
+ this macro with the value zero. You can override the default
+ splitting-length by defining this macro as an expression for the
+ length you desire.
+
+`DBX_CONTIN_CHAR'
+ Normally continuation is indicated by adding a `\' character to
+ the end of a `.stabs' string when a continuation follows. To use
+ a different character instead, define this macro as a character
+ constant for the character you want to use. Do not define this
+ macro if backslash is correct for your system.
+
+`DBX_STATIC_STAB_DATA_SECTION'
+ Define this macro if it is necessary to go to the data section
+ before outputting the `.stabs' pseudo-op for a non-global static
+ variable.
+
+`DBX_TYPE_DECL_STABS_CODE'
+ The value to use in the "code" field of the `.stabs' directive for
+ a typedef. The default is `N_LSYM'.
+
+`DBX_STATIC_CONST_VAR_CODE'
+ The value to use in the "code" field of the `.stabs' directive for
+ a static variable located in the text section. DBX format does not
+ provide any "right" way to do this. The default is `N_FUN'.
+
+`DBX_REGPARM_STABS_CODE'
+ The value to use in the "code" field of the `.stabs' directive for
+ a parameter passed in registers. DBX format does not provide any
+ "right" way to do this. The default is `N_RSYM'.
+
+`DBX_REGPARM_STABS_LETTER'
+ The letter to use in DBX symbol data to identify a symbol as a
+ parameter passed in registers. DBX format does not customarily
+ provide any way to do this. The default is `'P''.
+
+`DBX_MEMPARM_STABS_LETTER'
+ The letter to use in DBX symbol data to identify a symbol as a
+ stack parameter. The default is `'p''.
+
+`DBX_FUNCTION_FIRST'
+ Define this macro if the DBX information for a function and its
+ arguments should precede the assembler code for the function.
+ Normally, in DBX format, the debugging information entirely
+ follows the assembler code.
+
+`DBX_LBRAC_FIRST'
+ Define this macro if the `N_LBRAC' symbol for a block should
+ precede the debugging information for variables and functions
+ defined in that block. Normally, in DBX format, the `N_LBRAC'
+ symbol comes first.
+
+`DBX_BLOCKS_FUNCTION_RELATIVE'
+ Define this macro if the value of a symbol describing the scope of
+ a block (`N_LBRAC' or `N_RBRAC') should be relative to the start
+ of the enclosing function. Normally, GCC uses an absolute address.
+
+`DBX_USE_BINCL'
+ Define this macro if GCC should generate `N_BINCL' and `N_EINCL'
+ stabs for included header files, as on Sun systems. This macro
+ also directs GCC to output a type number as a pair of a file
+ number and a type number within the file. Normally, GCC does not
+ generate `N_BINCL' or `N_EINCL' stabs, and it outputs a single
+ number for a type number.
- The following macros and functions can be used on a `FUNCTION_DECL':
-`DECL_MAIN_P'
- This predicate holds for a function that is the program entry point
- `::code'.
+\1f
+File: gccint.info, Node: DBX Hooks, Next: File Names and DBX, Prev: DBX Options, Up: Debugging Info
+
+10.21.3 Open-Ended Hooks for DBX Format
+---------------------------------------
+
+These are hooks for DBX format.
+
+`DBX_OUTPUT_LBRAC (STREAM, NAME)'
+ Define this macro to say how to output to STREAM the debugging
+ information for the start of a scope level for variable names. The
+ argument NAME is the name of an assembler symbol (for use with
+ `assemble_name') whose value is the address where the scope begins.
+
+`DBX_OUTPUT_RBRAC (STREAM, NAME)'
+ Like `DBX_OUTPUT_LBRAC', but for the end of a scope level.
+
+`DBX_OUTPUT_NFUN (STREAM, LSCOPE_LABEL, DECL)'
+ Define this macro if the target machine requires special handling
+ to output an `N_FUN' entry for the function DECL.
+
+`DBX_OUTPUT_ENUM (STREAM, TYPE)'
+ Define this macro if the target machine requires special handling
+ to output an enumeration type. The definition should be a C
+ statement (sans semicolon) to output the appropriate information
+ to STREAM for the type TYPE.
+
+`DBX_OUTPUT_FUNCTION_END (STREAM, FUNCTION)'
+ Define this macro if the target machine requires special output at
+ the end of the debugging information for a function. The
+ definition should be a C statement (sans semicolon) to output the
+ appropriate information to STREAM. FUNCTION is the
+ `FUNCTION_DECL' node for the function.
+
+`DBX_OUTPUT_STANDARD_TYPES (SYMS)'
+ Define this macro if you need to control the order of output of the
+ standard data types at the beginning of compilation. The argument
+ SYMS is a `tree' which is a chain of all the predefined global
+ symbols, including names of data types.
+
+ Normally, DBX output starts with definitions of the types for
+ integers and characters, followed by all the other predefined
+ types of the particular language in no particular order.
+
+ On some machines, it is necessary to output different particular
+ types first. To do this, define `DBX_OUTPUT_STANDARD_TYPES' to
+ output those symbols in the necessary order. Any predefined types
+ that you don't explicitly output will be output afterward in no
+ particular order.
+
+ Be careful not to define this macro so that it works only for C.
+ There are no global variables to access most of the built-in
+ types, because another language may have another set of types.
+ The way to output a particular type is to look through SYMS to see
+ if you can find it. Here is an example:
+
+ {
+ tree decl;
+ for (decl = syms; decl; decl = TREE_CHAIN (decl))
+ if (!strcmp (IDENTIFIER_POINTER (DECL_NAME (decl)),
+ "long int"))
+ dbxout_symbol (decl);
+ ...
+ }
+
+ This does nothing if the expected type does not exist.
+
+ See the function `init_decl_processing' in `c-decl.c' to find the
+ names to use for all the built-in C types.
+
+ Here is another way of finding a particular type:
+
+ {
+ tree decl;
+ for (decl = syms; decl; decl = TREE_CHAIN (decl))
+ if (TREE_CODE (decl) == TYPE_DECL
+ && (TREE_CODE (TREE_TYPE (decl))
+ == INTEGER_CST)
+ && TYPE_PRECISION (TREE_TYPE (decl)) == 16
+ && TYPE_UNSIGNED (TREE_TYPE (decl)))
+ /* This must be `unsigned short'. */
+ dbxout_symbol (decl);
+ ...
+ }
+
+`NO_DBX_FUNCTION_END'
+ Some stabs encapsulation formats (in particular ECOFF), cannot
+ handle the `.stabs "",N_FUN,,0,0,Lscope-function-1' gdb dbx
+ extension construct. On those machines, define this macro to turn
+ this feature off without disturbing the rest of the gdb extensions.
-`DECL_NAME'
- This macro returns the unqualified name of the function, as an
- `IDENTIFIER_NODE'. For an instantiation of a function template,
- the `DECL_NAME' is the unqualified name of the template, not
- something like `f<int>'. The value of `DECL_NAME' is undefined
- when used on a constructor, destructor, overloaded operator, or
- type-conversion operator, or any function that is implicitly
- generated by the compiler. See below for macros that can be used
- to distinguish these cases.
-`DECL_ASSEMBLER_NAME'
- This macro returns the mangled name of the function, also an
- `IDENTIFIER_NODE'. This name does not contain leading underscores
- on systems that prefix all identifiers with underscores. The
- mangled name is computed in the same way on all platforms; if
- special processing is required to deal with the object file format
- used on a particular platform, it is the responsibility of the
- back end to perform those modifications. (Of course, the back end
- should not modify `DECL_ASSEMBLER_NAME' itself.)
+\1f
+File: gccint.info, Node: File Names and DBX, Next: SDB and DWARF, Prev: DBX Hooks, Up: Debugging Info
-`DECL_EXTERNAL'
- This predicate holds if the function is undefined.
+10.21.4 File Names in DBX Format
+--------------------------------
-`TREE_PUBLIC'
- This predicate holds if the function has external linkage.
+This describes file names in DBX format.
-`DECL_LOCAL_FUNCTION_P'
- This predicate holds if the function was declared at block scope,
- even though it has a global scope.
+`DBX_WORKING_DIRECTORY'
+ Define this if DBX wants to have the current directory recorded in
+ each object file.
-`DECL_ANTICIPATED'
- This predicate holds if the function is a built-in function but its
- prototype is not yet explicitly declared.
+ Note that the working directory is always recorded if GDB
+ extensions are enabled.
-`DECL_EXTERN_C_FUNCTION_P'
- This predicate holds if the function is declared as an ``extern
- "C"'' function.
+`DBX_OUTPUT_MAIN_SOURCE_FILENAME (STREAM, NAME)'
+ A C statement to output DBX debugging information to the stdio
+ stream STREAM which indicates that file NAME is the main source
+ file--the file specified as the input file for compilation. This
+ macro is called only once, at the beginning of compilation.
-`DECL_LINKONCE_P'
- This macro holds if multiple copies of this function may be
- emitted in various translation units. It is the responsibility of
- the linker to merge the various copies. Template instantiations
- are the most common example of functions for which
- `DECL_LINKONCE_P' holds; G++ instantiates needed templates in all
- translation units which require them, and then relies on the
- linker to remove duplicate instantiations.
+ This macro need not be defined if the standard form of output for
+ DBX debugging information is appropriate.
- FIXME: This macro is not yet implemented.
+`DBX_OUTPUT_MAIN_SOURCE_DIRECTORY (STREAM, NAME)'
+ A C statement to output DBX debugging information to the stdio
+ stream STREAM which indicates that the current directory during
+ compilation is named NAME.
-`DECL_FUNCTION_MEMBER_P'
- This macro holds if the function is a member of a class, rather
- than a member of a namespace.
+ This macro need not be defined if the standard form of output for
+ DBX debugging information is appropriate.
-`DECL_STATIC_FUNCTION_P'
- This predicate holds if the function a static member function.
+`DBX_OUTPUT_MAIN_SOURCE_FILE_END (STREAM, NAME)'
+ A C statement to output DBX debugging information at the end of
+ compilation of the main source file NAME.
-`DECL_NONSTATIC_MEMBER_FUNCTION_P'
- This macro holds for a non-static member function.
+ If you don't define this macro, nothing special is output at the
+ end of compilation, which is correct for most machines.
-`DECL_CONST_MEMFUNC_P'
- This predicate holds for a `const'-member function.
+`DBX_OUTPUT_SOURCE_FILENAME (STREAM, NAME)'
+ A C statement to output DBX debugging information to the stdio
+ stream STREAM which indicates that file NAME is the current source
+ file. This output is generated each time input shifts to a
+ different source file as a result of `#include', the end of an
+ included file, or a `#line' command.
-`DECL_VOLATILE_MEMFUNC_P'
- This predicate holds for a `volatile'-member function.
+ This macro need not be defined if the standard form of output for
+ DBX debugging information is appropriate.
-`DECL_CONSTRUCTOR_P'
- This macro holds if the function is a constructor.
+\1f
+File: gccint.info, Node: SDB and DWARF, Next: VMS Debug, Prev: File Names and DBX, Up: Debugging Info
+
+10.21.5 Macros for SDB and DWARF Output
+---------------------------------------
+
+Here are macros for SDB and DWARF output.
+
+`SDB_DEBUGGING_INFO'
+ Define this macro if GCC should produce COFF-style debugging output
+ for SDB in response to the `-g' option.
+
+`DWARF_DEBUGGING_INFO'
+ Define this macro if GCC should produce dwarf format debugging
+ output in response to the `-g' option.
+
+`DWARF2_DEBUGGING_INFO'
+ Define this macro if GCC should produce dwarf version 2 format
+ debugging output in response to the `-g' option.
+
+ To support optional call frame debugging information, you must also
+ define `INCOMING_RETURN_ADDR_RTX' and either set
+ `RTX_FRAME_RELATED_P' on the prologue insns if you use RTL for the
+ prologue, or call `dwarf2out_def_cfa' and `dwarf2out_reg_save' as
+ appropriate from `TARGET_ASM_FUNCTION_PROLOGUE' if you don't.
+
+`DWARF2_FRAME_INFO'
+ Define this macro to a nonzero value if GCC should always output
+ Dwarf 2 frame information. If `DWARF2_UNWIND_INFO' (*note
+ Exception Region Output:: is nonzero, GCC will output this
+ information not matter how you define `DWARF2_FRAME_INFO'.
+
+`LINKER_DOES_NOT_WORK_WITH_DWARF2'
+ Define this macro if the linker does not work with Dwarf version 2.
+ Normally, if the user specifies only `-ggdb' GCC will use Dwarf
+ version 2 if available; this macro disables this. See the
+ description of the `PREFERRED_DEBUGGING_TYPE' macro for more
+ details.
+
+`DWARF2_GENERATE_TEXT_SECTION_LABEL'
+ By default, the Dwarf 2 debugging information generator will
+ generate a label to mark the beginning of the text section. If it
+ is better simply to use the name of the text section itself,
+ rather than an explicit label, to indicate the beginning of the
+ text section, define this macro to zero.
+
+`DWARF2_ASM_LINE_DEBUG_INFO'
+ Define this macro to be a nonzero value if the assembler can
+ generate Dwarf 2 line debug info sections. This will result in
+ much more compact line number tables, and hence is desirable if it
+ works.
+
+`PUT_SDB_...'
+ Define these macros to override the assembler syntax for the
+ special SDB assembler directives. See `sdbout.c' for a list of
+ these macros and their arguments. If the standard syntax is used,
+ you need not define them yourself.
+
+`SDB_DELIM'
+ Some assemblers do not support a semicolon as a delimiter, even
+ between SDB assembler directives. In that case, define this macro
+ to be the delimiter to use (usually `\n'). It is not necessary to
+ define a new set of `PUT_SDB_OP' macros if this is the only change
+ required.
+
+`SDB_GENERATE_FAKE'
+ Define this macro to override the usual method of constructing a
+ dummy name for anonymous structure and union types. See
+ `sdbout.c' for more information.
+
+`SDB_ALLOW_UNKNOWN_REFERENCES'
+ Define this macro to allow references to unknown structure, union,
+ or enumeration tags to be emitted. Standard COFF does not allow
+ handling of unknown references, MIPS ECOFF has support for it.
+
+`SDB_ALLOW_FORWARD_REFERENCES'
+ Define this macro to allow references to structure, union, or
+ enumeration tags that have not yet been seen to be handled. Some
+ assemblers choke if forward tags are used, while some require it.
-`DECL_NONCONVERTING_P'
- This predicate holds if the constructor is a non-converting
- constructor.
+\1f
+File: gccint.info, Node: VMS Debug, Prev: SDB and DWARF, Up: Debugging Info
-`DECL_COMPLETE_CONSTRUCTOR_P'
- This predicate holds for a function which is a constructor for an
- object of a complete type.
+10.21.6 Macros for VMS Debug Format
+-----------------------------------
-`DECL_BASE_CONSTRUCTOR_P'
- This predicate holds for a function which is a constructor for a
- base class sub-object.
+Here are macros for VMS debug format.
-`DECL_COPY_CONSTRUCTOR_P'
- This predicate holds for a function which is a copy-constructor.
+`VMS_DEBUGGING_INFO'
+ Define this macro if GCC should produce debugging output for VMS
+ in response to the `-g' option. The default behavior for VMS is
+ to generate minimal debug info for a traceback in the absence of
+ `-g' unless explicitly overridden with `-g0'. This behavior is
+ controlled by `OPTIMIZATION_OPTIONS' and `OVERRIDE_OPTIONS'.
-`DECL_DESTRUCTOR_P'
- This macro holds if the function is a destructor.
+\1f
+File: gccint.info, Node: Cross-compilation, Next: Mode Switching, Prev: Debugging Info, Up: Target Macros
+
+10.22 Cross Compilation and Floating Point
+==========================================
+
+While all modern machines use 2's complement representation for
+integers, there are a variety of representations for floating point
+numbers. This means that in a cross-compiler the representation of
+floating point numbers in the compiled program may be different from
+that used in the machine doing the compilation.
+
+ Because different representation systems may offer different amounts
+of range and precision, the cross compiler cannot safely use the host
+machine's floating point arithmetic. Therefore, floating point
+constants must be represented in the target machine's format. This
+means that the cross compiler cannot use `atof' to parse a floating
+point constant; it must have its own special routine to use instead.
+Also, constant folding must emulate the target machine's arithmetic (or
+must not be done at all).
+
+ The macros in the following table should be defined only if you are
+cross compiling between different floating point formats.
+
+ Otherwise, don't define them. Then default definitions will be set
+up which use `double' as the data type, `==' to test for equality, etc.
+
+ You don't need to worry about how many times you use an operand of
+any of these macros. The compiler never uses operands which have side
+effects.
+
+`REAL_VALUE_TYPE'
+ A macro for the C data type to be used to hold a floating point
+ value in the target machine's format. Typically this would be a
+ `struct' containing an array of `int'.
+
+`REAL_VALUES_EQUAL (X, Y)'
+ A macro for a C expression which compares for equality the two
+ values, X and Y, both of type `REAL_VALUE_TYPE'.
+
+`REAL_VALUES_LESS (X, Y)'
+ A macro for a C expression which tests whether X is less than Y,
+ both values being of type `REAL_VALUE_TYPE' and interpreted as
+ floating point numbers in the target machine's representation.
+
+`REAL_VALUE_LDEXP (X, SCALE)'
+ A macro for a C expression which performs the standard library
+ function `ldexp', but using the target machine's floating point
+ representation. Both X and the value of the expression have type
+ `REAL_VALUE_TYPE'. The second argument, SCALE, is an integer.
+
+`REAL_VALUE_FIX (X)'
+ A macro whose definition is a C expression to convert the
+ target-machine floating point value X to a signed integer. X has
+ type `REAL_VALUE_TYPE'.
+
+`REAL_VALUE_UNSIGNED_FIX (X)'
+ A macro whose definition is a C expression to convert the
+ target-machine floating point value X to an unsigned integer. X
+ has type `REAL_VALUE_TYPE'.
+
+`REAL_VALUE_RNDZINT (X)'
+ A macro whose definition is a C expression to round the
+ target-machine floating point value X towards zero to an integer
+ value (but still as a floating point number). X has type
+ `REAL_VALUE_TYPE', and so does the value.
+
+`REAL_VALUE_UNSIGNED_RNDZINT (X)'
+ A macro whose definition is a C expression to round the
+ target-machine floating point value X towards zero to an unsigned
+ integer value (but still represented as a floating point number).
+ X has type `REAL_VALUE_TYPE', and so does the value.
+
+`REAL_VALUE_ATOF (STRING, MODE)'
+ A macro for a C expression which converts STRING, an expression of
+ type `char *', into a floating point number in the target machine's
+ representation for mode MODE. The value has type
+ `REAL_VALUE_TYPE'.
+
+`REAL_INFINITY'
+ Define this macro if infinity is a possible floating point value,
+ and therefore division by 0 is legitimate.
+
+`REAL_VALUE_ISINF (X)'
+ A macro for a C expression which determines whether X, a floating
+ point value, is infinity. The value has type `int'. By default,
+ this is defined to call `isinf'.
+
+`REAL_VALUE_ISNAN (X)'
+ A macro for a C expression which determines whether X, a floating
+ point value, is a "nan" (not-a-number). The value has type `int'.
+ By default, this is defined to call `isnan'.
+
+ Define the following additional macros if you want to make floating
+point constant folding work while cross compiling. If you don't define
+them, cross compilation is still possible, but constant folding will
+not happen for floating point values.
+
+`REAL_ARITHMETIC (OUTPUT, CODE, X, Y)'
+ A macro for a C statement which calculates an arithmetic operation
+ of the two floating point values X and Y, both of type
+ `REAL_VALUE_TYPE' in the target machine's representation, to
+ produce a result of the same type and representation which is
+ stored in OUTPUT (which will be a variable).
+
+ The operation to be performed is specified by CODE, a tree code
+ which will always be one of the following: `PLUS_EXPR',
+ `MINUS_EXPR', `MULT_EXPR', `RDIV_EXPR', `MAX_EXPR', `MIN_EXPR'.
+
+ The expansion of this macro is responsible for checking for
+ overflow. If overflow happens, the macro expansion should execute
+ the statement `return 0;', which indicates the inability to
+ perform the arithmetic operation requested.
+
+`REAL_VALUE_NEGATE (X)'
+ A macro for a C expression which returns the negative of the
+ floating point value X. Both X and the value of the expression
+ have type `REAL_VALUE_TYPE' and are in the target machine's
+ floating point representation.
+
+ There is no way for this macro to report overflow, since overflow
+ can't happen in the negation operation.
+
+`REAL_VALUE_TRUNCATE (MODE, X)'
+ A macro for a C expression which converts the floating point value
+ X to mode MODE.
+
+ Both X and the value of the expression are in the target machine's
+ floating point representation and have type `REAL_VALUE_TYPE'.
+ However, the value should have an appropriate bit pattern to be
+ output properly as a floating constant whose precision accords
+ with mode MODE.
+
+ There is no way for this macro to report overflow.
+
+`REAL_VALUE_TO_INT (LOW, HIGH, X)'
+ A macro for a C expression which converts a floating point value X
+ into a double-precision integer which is then stored into LOW and
+ HIGH, two variables of type INT.
+
+`REAL_VALUE_FROM_INT (X, LOW, HIGH, MODE)'
+ A macro for a C expression which converts a double-precision
+ integer found in LOW and HIGH, two variables of type INT, into a
+ floating point value which is then stored into X. The value is in
+ the target machine's representation for mode MODE and has the type
+ `REAL_VALUE_TYPE'.
-`DECL_COMPLETE_DESTRUCTOR_P'
- This predicate holds if the function is the destructor for an
- object a complete type.
+\1f
+File: gccint.info, Node: Mode Switching, Next: Target Attributes, Prev: Cross-compilation, Up: Target Macros
+
+10.23 Mode Switching Instructions
+=================================
+
+The following macros control mode switching optimizations:
+
+`OPTIMIZE_MODE_SWITCHING (ENTITY)'
+ Define this macro if the port needs extra instructions inserted
+ for mode switching in an optimizing compilation.
+
+ For an example, the SH4 can perform both single and double
+ precision floating point operations, but to perform a single
+ precision operation, the FPSCR PR bit has to be cleared, while for
+ a double precision operation, this bit has to be set. Changing
+ the PR bit requires a general purpose register as a scratch
+ register, hence these FPSCR sets have to be inserted before
+ reload, i.e. you can't put this into instruction emitting or
+ `MACHINE_DEPENDENT_REORG'.
+
+ You can have multiple entities that are mode-switched, and select
+ at run time which entities actually need it.
+ `OPTIMIZE_MODE_SWITCHING' should return nonzero for any ENTITY
+ that needs mode-switching. If you define this macro, you also
+ have to define `NUM_MODES_FOR_MODE_SWITCHING', `MODE_NEEDED',
+ `MODE_PRIORITY_TO_MODE' and `EMIT_MODE_SET'. `NORMAL_MODE' is
+ optional.
+
+`NUM_MODES_FOR_MODE_SWITCHING'
+ If you define `OPTIMIZE_MODE_SWITCHING', you have to define this as
+ initializer for an array of integers. Each initializer element N
+ refers to an entity that needs mode switching, and specifies the
+ number of different modes that might need to be set for this
+ entity. The position of the initializer in the initializer -
+ starting counting at zero - determines the integer that is used to
+ refer to the mode-switched entity in question. In macros that
+ take mode arguments / yield a mode result, modes are represented
+ as numbers 0 ... N - 1. N is used to specify that no mode switch
+ is needed / supplied.
+
+`MODE_NEEDED (ENTITY, INSN)'
+ ENTITY is an integer specifying a mode-switched entity. If
+ `OPTIMIZE_MODE_SWITCHING' is defined, you must define this macro to
+ return an integer value not larger than the corresponding element
+ in `NUM_MODES_FOR_MODE_SWITCHING', to denote the mode that ENTITY
+ must be switched into prior to the execution of INSN.
+
+`NORMAL_MODE (ENTITY)'
+ If this macro is defined, it is evaluated for every ENTITY that
+ needs mode switching. It should evaluate to an integer, which is
+ a mode that ENTITY is assumed to be switched to at function entry
+ and exit.
+
+`MODE_PRIORITY_TO_MODE (ENTITY, N)'
+ This macro specifies the order in which modes for ENTITY are
+ processed. 0 is the highest priority,
+ `NUM_MODES_FOR_MODE_SWITCHING[ENTITY] - 1' the lowest. The value
+ of the macro should be an integer designating a mode for ENTITY.
+ For any fixed ENTITY, `mode_priority_to_mode' (ENTITY, N) shall be
+ a bijection in 0 ... `num_modes_for_mode_switching[ENTITY] - 1'.
+
+`EMIT_MODE_SET (ENTITY, MODE, HARD_REGS_LIVE)'
+ Generate one or more insns to set ENTITY to MODE. HARD_REG_LIVE
+ is the set of hard registers live at the point where the insn(s)
+ are to be inserted.
-`DECL_OVERLOADED_OPERATOR_P'
- This macro holds if the function is an overloaded operator.
-
-`DECL_CONV_FN_P'
- This macro holds if the function is a type-conversion operator.
-
-`DECL_GLOBAL_CTOR_P'
- This predicate holds if the function is a file-scope initialization
- function.
+\1f
+File: gccint.info, Node: Target Attributes, Next: Misc, Prev: Mode Switching, Up: Target Macros
+
+10.24 Defining target-specific uses of `__attribute__'
+======================================================
+
+Target-specific attributes may be defined for functions, data and types.
+These are described using the following target hooks; they also need to
+be documented in `extend.texi'.
+
+ -- Target Hook: const struct attribute_spec * TARGET_ATTRIBUTE_TABLE
+ If defined, this target hook points to an array of `struct
+ attribute_spec' (defined in `tree.h') specifying the machine
+ specific attributes for this target and some of the restrictions
+ on the entities to which these attributes are applied and the
+ arguments they take.
+
+ -- Target Hook: int TARGET_COMP_TYPE_ATTRIBUTES (tree TYPE1, tree
+ TYPE2)
+ If defined, this target hook is a function which returns zero if
+ the attributes on TYPE1 and TYPE2 are incompatible, one if they
+ are compatible, and two if they are nearly compatible (which
+ causes a warning to be generated). If this is not defined,
+ machine-specific attributes are supposed always to be compatible.
+
+ -- Target Hook: void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree TYPE)
+ If defined, this target hook is a function which assigns default
+ attributes to newly defined TYPE.
+
+ -- Target Hook: tree TARGET_MERGE_TYPE_ATTRIBUTES (tree TYPE1, tree
+ TYPE2)
+ Define this target hook if the merging of type attributes needs
+ special handling. If defined, the result is a list of the combined
+ `TYPE_ATTRIBUTES' of TYPE1 and TYPE2. It is assumed that
+ `comptypes' has already been called and returned 1. This function
+ may call `merge_attributes' to handle machine-independent merging.
+
+ -- Target Hook: tree TARGET_MERGE_DECL_ATTRIBUTES (tree OLDDECL, tree
+ NEWDECL)
+ Define this target hook if the merging of decl attributes needs
+ special handling. If defined, the result is a list of the combined
+ `DECL_ATTRIBUTES' of OLDDECL and NEWDECL. NEWDECL is a duplicate
+ declaration of OLDDECL. Examples of when this is needed are when
+ one attribute overrides another, or when an attribute is nullified
+ by a subsequent definition. This function may call
+ `merge_attributes' to handle machine-independent merging.
+
+ If the only target-specific handling you require is `dllimport' for
+ Windows targets, you should define the macro
+ `TARGET_DLLIMPORT_DECL_ATTRIBUTES'. This links in a function
+ called `merge_dllimport_decl_attributes' which can then be defined
+ as the expansion of `TARGET_MERGE_DECL_ATTRIBUTES'. This is done
+ in `i386/cygwin.h' and `i386/i386.c', for example.
+
+ -- Target Hook: void TARGET_INSERT_ATTRIBUTES (tree NODE, tree
+ *ATTR_PTR)
+ Define this target hook if you want to be able to add attributes
+ to a decl when it is being created. This is normally useful for
+ back ends which wish to implement a pragma by using the attributes
+ which correspond to the pragma's effect. The NODE argument is the
+ decl which is being created. The ATTR_PTR argument is a pointer
+ to the attribute list for this decl. The list itself should not
+ be modified, since it may be shared with other decls, but
+ attributes may be chained on the head of the list and `*ATTR_PTR'
+ modified to point to the new attributes, or a copy of the list may
+ be made if further changes are needed.
+
+ -- Target Hook: bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (tree
+ FNDECL)
+ This target hook returns `true' if it is ok to inline FNDECL into
+ the current function, despite its having target-specific
+ attributes, `false' otherwise. By default, if a function has a
+ target specific attribute attached to it, it will not be inlined.
-`DECL_GLOBAL_DTOR_P'
- This predicate holds if the function is a file-scope finalization
- function.
+\1f
+File: gccint.info, Node: Misc, Prev: Target Attributes, Up: Target Macros
+
+10.25 Miscellaneous Parameters
+==============================
+
+Here are several miscellaneous parameters.
+
+`PREDICATE_CODES'
+ Define this if you have defined special-purpose predicates in the
+ file `MACHINE.c'. This macro is called within an initializer of an
+ array of structures. The first field in the structure is the name
+ of a predicate and the second field is an array of rtl codes. For
+ each predicate, list all rtl codes that can be in expressions
+ matched by the predicate. The list should have a trailing comma.
+ Here is an example of two entries in the list for a typical RISC
+ machine:
+
+ #define PREDICATE_CODES \
+ {"gen_reg_rtx_operand", {SUBREG, REG}}, \
+ {"reg_or_short_cint_operand", {SUBREG, REG, CONST_INT}},
+
+ Defining this macro does not affect the generated code (however,
+ incorrect definitions that omit an rtl code that may be matched by
+ the predicate can cause the compiler to malfunction). Instead, it
+ allows the table built by `genrecog' to be more compact and
+ efficient, thus speeding up the compiler. The most important
+ predicates to include in the list specified by this macro are
+ those used in the most insn patterns.
+
+ For each predicate function named in `PREDICATE_CODES', a
+ declaration will be generated in `insn-codes.h'.
+
+`SPECIAL_MODE_PREDICATES'
+ Define this if you have special predicates that know special things
+ about modes. Genrecog will warn about certain forms of
+ `match_operand' without a mode; if the operand predicate is listed
+ in `SPECIAL_MODE_PREDICATES', the warning will be suppressed.
+
+ Here is an example from the IA-32 port (`ext_register_operand'
+ specially checks for `HImode' or `SImode' in preparation for a
+ byte extraction from `%ah' etc.).
+
+ #define SPECIAL_MODE_PREDICATES \
+ "ext_register_operand",
+
+`CASE_VECTOR_MODE'
+ An alias for a machine mode name. This is the machine mode that
+ elements of a jump-table should have.
+
+`CASE_VECTOR_SHORTEN_MODE (MIN_OFFSET, MAX_OFFSET, BODY)'
+ Optional: return the preferred mode for an `addr_diff_vec' when
+ the minimum and maximum offset are known. If you define this, it
+ enables extra code in branch shortening to deal with
+ `addr_diff_vec'. To make this work, you also have to define
+ INSN_ALIGN and make the alignment for `addr_diff_vec' explicit.
+ The BODY argument is provided so that the offset_unsigned and scale
+ flags can be updated.
+
+`CASE_VECTOR_PC_RELATIVE'
+ Define this macro to be a C expression to indicate when jump-tables
+ should contain relative addresses. If jump-tables never contain
+ relative addresses, then you need not define this macro.
+
+`CASE_DROPS_THROUGH'
+ Define this if control falls through a `case' insn when the index
+ value is out of range. This means the specified default-label is
+ actually ignored by the `case' insn proper.
+
+`CASE_VALUES_THRESHOLD'
+ Define this to be the smallest number of different values for
+ which it is best to use a jump-table instead of a tree of
+ conditional branches. The default is four for machines with a
+ `casesi' instruction and five otherwise. This is best for most
+ machines.
+
+`WORD_REGISTER_OPERATIONS'
+ Define this macro if operations between registers with integral
+ mode smaller than a word are always performed on the entire
+ register. Most RISC machines have this property and most CISC
+ machines do not.
+
+`LOAD_EXTEND_OP (MODE)'
+ Define this macro to be a C expression indicating when insns that
+ read memory in MODE, an integral mode narrower than a word, set the
+ bits outside of MODE to be either the sign-extension or the
+ zero-extension of the data read. Return `SIGN_EXTEND' for values
+ of MODE for which the insn sign-extends, `ZERO_EXTEND' for which
+ it zero-extends, and `NIL' for other modes.
+
+ This macro is not called with MODE non-integral or with a width
+ greater than or equal to `BITS_PER_WORD', so you may return any
+ value in this case. Do not define this macro if it would always
+ return `NIL'. On machines where this macro is defined, you will
+ normally define it as the constant `SIGN_EXTEND' or `ZERO_EXTEND'.
+
+`SHORT_IMMEDIATES_SIGN_EXTEND'
+ Define this macro if loading short immediate values into registers
+ sign extends.
+
+`FIXUNS_TRUNC_LIKE_FIX_TRUNC'
+ Define this macro if the same instructions that convert a floating
+ point number to a signed fixed point number also convert validly
+ to an unsigned one.
+
+`MOVE_MAX'
+ The maximum number of bytes that a single instruction can move
+ quickly between memory and registers or between two memory
+ locations.
+
+`MAX_MOVE_MAX'
+ The maximum number of bytes that a single instruction can move
+ quickly between memory and registers or between two memory
+ locations. If this is undefined, the default is `MOVE_MAX'.
+ Otherwise, it is the constant value that is the largest value that
+ `MOVE_MAX' can have at run-time.
+
+`SHIFT_COUNT_TRUNCATED'
+ A C expression that is nonzero if on this machine the number of
+ bits actually used for the count of a shift operation is equal to
+ the number of bits needed to represent the size of the object
+ being shifted. When this macro is nonzero, the compiler will
+ assume that it is safe to omit a sign-extend, zero-extend, and
+ certain bitwise `and' instructions that truncates the count of a
+ shift operation. On machines that have instructions that act on
+ bit-fields at variable positions, which may include `bit test'
+ instructions, a nonzero `SHIFT_COUNT_TRUNCATED' also enables
+ deletion of truncations of the values that serve as arguments to
+ bit-field instructions.
+
+ If both types of instructions truncate the count (for shifts) and
+ position (for bit-field operations), or if no variable-position
+ bit-field instructions exist, you should define this macro.
+
+ However, on some machines, such as the 80386 and the 680x0,
+ truncation only applies to shift operations and not the (real or
+ pretended) bit-field operations. Define `SHIFT_COUNT_TRUNCATED'
+ to be zero on such machines. Instead, add patterns to the `md'
+ file that include the implied truncation of the shift instructions.
+
+ You need not define this macro if it would always have the value
+ of zero.
+
+`TRULY_NOOP_TRUNCATION (OUTPREC, INPREC)'
+ A C expression which is nonzero if on this machine it is safe to
+ "convert" an integer of INPREC bits to one of OUTPREC bits (where
+ OUTPREC is smaller than INPREC) by merely operating on it as if it
+ had only OUTPREC bits.
+
+ On many machines, this expression can be 1.
+
+ When `TRULY_NOOP_TRUNCATION' returns 1 for a pair of sizes for
+ modes for which `MODES_TIEABLE_P' is 0, suboptimal code can result.
+ If this is the case, making `TRULY_NOOP_TRUNCATION' return 0 in
+ such cases may improve things.
+
+`STORE_FLAG_VALUE'
+ A C expression describing the value returned by a comparison
+ operator with an integral mode and stored by a store-flag
+ instruction (`sCOND') when the condition is true. This
+ description must apply to _all_ the `sCOND' patterns and all the
+ comparison operators whose results have a `MODE_INT' mode.
+
+ A value of 1 or -1 means that the instruction implementing the
+ comparison operator returns exactly 1 or -1 when the comparison is
+ true and 0 when the comparison is false. Otherwise, the value
+ indicates which bits of the result are guaranteed to be 1 when the
+ comparison is true. This value is interpreted in the mode of the
+ comparison operation, which is given by the mode of the first
+ operand in the `sCOND' pattern. Either the low bit or the sign
+ bit of `STORE_FLAG_VALUE' be on. Presently, only those bits are
+ used by the compiler.
+
+ If `STORE_FLAG_VALUE' is neither 1 or -1, the compiler will
+ generate code that depends only on the specified bits. It can also
+ replace comparison operators with equivalent operations if they
+ cause the required bits to be set, even if the remaining bits are
+ undefined. For example, on a machine whose comparison operators
+ return an `SImode' value and where `STORE_FLAG_VALUE' is defined as
+ `0x80000000', saying that just the sign bit is relevant, the
+ expression
+
+ (ne:SI (and:SI X (const_int POWER-OF-2)) (const_int 0))
+
+ can be converted to
+
+ (ashift:SI X (const_int N))
+
+ where N is the appropriate shift count to move the bit being
+ tested into the sign bit.
+
+ There is no way to describe a machine that always sets the
+ low-order bit for a true value, but does not guarantee the value
+ of any other bits, but we do not know of any machine that has such
+ an instruction. If you are trying to port GCC to such a machine,
+ include an instruction to perform a logical-and of the result with
+ 1 in the pattern for the comparison operators and let us know at
+ <gcc@gcc.gnu.org>.
+
+ Often, a machine will have multiple instructions that obtain a
+ value from a comparison (or the condition codes). Here are rules
+ to guide the choice of value for `STORE_FLAG_VALUE', and hence the
+ instructions to be used:
+
+ * Use the shortest sequence that yields a valid definition for
+ `STORE_FLAG_VALUE'. It is more efficient for the compiler to
+ "normalize" the value (convert it to, e.g., 1 or 0) than for
+ the comparison operators to do so because there may be
+ opportunities to combine the normalization with other
+ operations.
+
+ * For equal-length sequences, use a value of 1 or -1, with -1
+ being slightly preferred on machines with expensive jumps and
+ 1 preferred on other machines.
+
+ * As a second choice, choose a value of `0x80000001' if
+ instructions exist that set both the sign and low-order bits
+ but do not define the others.
+
+ * Otherwise, use a value of `0x80000000'.
+
+ Many machines can produce both the value chosen for
+ `STORE_FLAG_VALUE' and its negation in the same number of
+ instructions. On those machines, you should also define a pattern
+ for those cases, e.g., one matching
+
+ (set A (neg:M (ne:M B C)))
+
+ Some machines can also perform `and' or `plus' operations on
+ condition code values with less instructions than the corresponding
+ `sCOND' insn followed by `and' or `plus'. On those machines,
+ define the appropriate patterns. Use the names `incscc' and
+ `decscc', respectively, for the patterns which perform `plus' or
+ `minus' operations on condition code values. See `rs6000.md' for
+ some examples. The GNU Superoptizer can be used to find such
+ instruction sequences on other machines.
+
+ You need not define `STORE_FLAG_VALUE' if the machine has no
+ store-flag instructions.
+
+`FLOAT_STORE_FLAG_VALUE (MODE)'
+ A C expression that gives a nonzero `REAL_VALUE_TYPE' value that is
+ returned when comparison operators with floating-point results are
+ true. Define this macro on machine that have comparison
+ operations that return floating-point values. If there are no
+ such operations, do not define this macro.
+
+`Pmode'
+ An alias for the machine mode for pointers. On most machines,
+ define this to be the integer mode corresponding to the width of a
+ hardware pointer; `SImode' on 32-bit machine or `DImode' on 64-bit
+ machines. On some machines you must define this to be one of the
+ partial integer modes, such as `PSImode'.
+
+ The width of `Pmode' must be at least as large as the value of
+ `POINTER_SIZE'. If it is not equal, you must define the macro
+ `POINTERS_EXTEND_UNSIGNED' to specify how pointers are extended to
+ `Pmode'.
+
+`FUNCTION_MODE'
+ An alias for the machine mode used for memory references to
+ functions being called, in `call' RTL expressions. On most
+ machines this should be `QImode'.
+
+`INTEGRATE_THRESHOLD (DECL)'
+ A C expression for the maximum number of instructions above which
+ the function DECL should not be inlined. DECL is a
+ `FUNCTION_DECL' node.
+
+ The default definition of this macro is 64 plus 8 times the number
+ of arguments that the function accepts. Some people think a larger
+ threshold should be used on RISC machines.
+
+`STDC_0_IN_SYSTEM_HEADERS'
+ In normal operation, the preprocessor expands `__STDC__' to the
+ constant 1, to signify that GCC conforms to ISO Standard C. On
+ some hosts, like Solaris, the system compiler uses a different
+ convention, where `__STDC__' is normally 0, but is 1 if the user
+ specifies strict conformance to the C Standard.
+
+ Defining `STDC_0_IN_SYSTEM_HEADERS' makes GNU CPP follows the host
+ convention when processing system header files, but when
+ processing user files `__STDC__' will always expand to 1.
+
+`SCCS_DIRECTIVE'
+ Define this if the preprocessor should ignore `#sccs' directives
+ and print no error message.
+
+`NO_IMPLICIT_EXTERN_C'
+ Define this macro if the system header files support C++ as well
+ as C. This macro inhibits the usual method of using system header
+ files in C++, which is to pretend that the file's contents are
+ enclosed in `extern "C" {...}'.
+
+`HANDLE_PRAGMA (GETC, UNGETC, NAME)'
+ This macro is no longer supported. You must use
+ `REGISTER_TARGET_PRAGMAS' instead.
+
+`REGISTER_TARGET_PRAGMAS (PFILE)'
+ Define this macro if you want to implement any target-specific
+ pragmas. If defined, it is a C expression which makes a series of
+ calls to `cpp_register_pragma' for each pragma, with PFILE passed
+ as the first argument to to these functions. The macro may also
+ do any setup required for the pragmas.
+
+ The primary reason to define this macro is to provide
+ compatibility with other compilers for the same target. In
+ general, we discourage definition of target-specific pragmas for
+ GCC.
+
+ If the pragma can be implemented by attributes then you should
+ consider defining the target hook `TARGET_INSERT_ATTRIBUTES' as
+ well.
+
+ Preprocessor macros that appear on pragma lines are not expanded.
+ All `#pragma' directives that do not match any registered pragma
+ are silently ignored, unless the user specifies
+ `-Wunknown-pragmas'.
+
+ -- Function: void cpp_register_pragma (cpp_reader *PFILE, const
+ char *SPACE, const char *NAME, void (*CALLBACK)
+ (cpp_reader *))
+ Each call to `cpp_register_pragma' establishes one pragma.
+ The CALLBACK routine will be called when the preprocessor
+ encounters a pragma of the form
+
+ #pragma [SPACE] NAME ...
+
+ SPACE is the case-sensitive namespace of the pragma, or
+ `NULL' to put the pragma in the global namespace. The
+ callback routine receives PFILE as its first argument, which
+ can be passed on to cpplib's functions if necessary. You can
+ lex tokens after the NAME by calling `c_lex'. Tokens that
+ are not read by the callback will be silently ignored. The
+ end of the line is indicated by a token of type `CPP_EOF'.
+
+ For an example use of this routine, see `c4x.h' and the
+ callback routines defined in `c4x-c.c'.
+
+ Note that the use of `c_lex' is specific to the C and C++
+ compilers. It will not work in the Java or Fortran
+ compilers, or any other language compilers for that matter.
+ Thus if `c_lex' is going to be called from target-specific
+ code, it must only be done so when building the C and C++
+ compilers. This can be done by defining the variables
+ `c_target_objs' and `cxx_target_objs' in the target entry in
+ the `config.gcc' file. These variables should name the
+ target-specific, language-specific object file which contains
+ the code that uses `c_lex'. Note it will also be necessary
+ to add a rule to the makefile fragment pointed to by
+ `tmake_file' that shows how to build this object file.
+
+`HANDLE_SYSV_PRAGMA'
+ Define this macro (to a value of 1) if you want the System V style
+ pragmas `#pragma pack(<n>)' and `#pragma weak <name> [=<value>]'
+ to be supported by gcc.
+
+ The pack pragma specifies the maximum alignment (in bytes) of
+ fields within a structure, in much the same way as the
+ `__aligned__' and `__packed__' `__attribute__'s do. A pack value
+ of zero resets the behavior to the default.
+
+ The weak pragma only works if `SUPPORTS_WEAK' and
+ `ASM_WEAKEN_LABEL' are defined. If enabled it allows the creation
+ of specifically named weak labels, optionally with a value.
+
+`HANDLE_PRAGMA_PACK_PUSH_POP'
+ Define this macro (to a value of 1) if you want to support the
+ Win32 style pragmas `#pragma pack(push,N)' and `#pragma
+ pack(pop)'. The `pack(push,N)' pragma specifies the maximum
+ alignment (in bytes) of fields within a structure, in much the
+ same way as the `__aligned__' and `__packed__' `__attribute__'s
+ do. A pack value of zero resets the behavior to the default.
+ Successive invocations of this pragma cause the previous values to
+ be stacked, so that invocations of `#pragma pack(pop)' will return
+ to the previous value.
+
+`DOLLARS_IN_IDENTIFIERS'
+ Define this macro to control use of the character `$' in identifier
+ names. 0 means `$' is not allowed by default; 1 means it is
+ allowed. 1 is the default; there is no need to define this macro
+ in that case. This macro controls the compiler proper; it does
+ not affect the preprocessor.
+
+`NO_DOLLAR_IN_LABEL'
+ Define this macro if the assembler does not accept the character
+ `$' in label names. By default constructors and destructors in
+ G++ have `$' in the identifiers. If this macro is defined, `.' is
+ used instead.
+
+`NO_DOT_IN_LABEL'
+ Define this macro if the assembler does not accept the character
+ `.' in label names. By default constructors and destructors in G++
+ have names that use `.'. If this macro is defined, these names
+ are rewritten to avoid `.'.
+
+`DEFAULT_MAIN_RETURN'
+ Define this macro if the target system expects every program's
+ `main' function to return a standard "success" value by default
+ (if no other value is explicitly returned).
+
+ The definition should be a C statement (sans semicolon) to
+ generate the appropriate rtl instructions. It is used only when
+ compiling the end of `main'.
+
+`NEED_ATEXIT'
+ Define this if the target system lacks the function `atexit' from
+ the ISO C standard. If this macro is defined, a default definition
+ will be provided to support C++. If `ON_EXIT' is not defined, a
+ default `exit' function will also be provided.
+
+`ON_EXIT'
+ Define this macro if the target has another way to implement atexit
+ functionality without replacing `exit'. For instance, SunOS 4 has
+ a similar `on_exit' library function.
+
+ The definition should be a functional macro which can be used just
+ like the `atexit' function.
+
+`EXIT_BODY'
+ Define this if your `exit' function needs to do something besides
+ calling an external function `_cleanup' before terminating with
+ `_exit'. The `EXIT_BODY' macro is only needed if `NEED_ATEXIT' is
+ defined and `ON_EXIT' is not defined.
+
+`INSN_SETS_ARE_DELAYED (INSN)'
+ Define this macro as a C expression that is nonzero if it is safe
+ for the delay slot scheduler to place instructions in the delay
+ slot of INSN, even if they appear to use a resource set or
+ clobbered in INSN. INSN is always a `jump_insn' or an `insn'; GCC
+ knows that every `call_insn' has this behavior. On machines where
+ some `insn' or `jump_insn' is really a function call and hence has
+ this behavior, you should define this macro.
+
+ You need not define this macro if it would always return zero.
+
+`INSN_REFERENCES_ARE_DELAYED (INSN)'
+ Define this macro as a C expression that is nonzero if it is safe
+ for the delay slot scheduler to place instructions in the delay
+ slot of INSN, even if they appear to set or clobber a resource
+ referenced in INSN. INSN is always a `jump_insn' or an `insn'.
+ On machines where some `insn' or `jump_insn' is really a function
+ call and its operands are registers whose use is actually in the
+ subroutine it calls, you should define this macro. Doing so
+ allows the delay slot scheduler to move instructions which copy
+ arguments into the argument registers into the delay slot of INSN.
+
+ You need not define this macro if it would always return zero.
+
+`MACHINE_DEPENDENT_REORG (INSN)'
+ In rare cases, correct code generation requires extra machine
+ dependent processing between the second jump optimization pass and
+ delayed branch scheduling. On those machines, define this macro
+ as a C statement to act on the code starting at INSN.
+
+`MULTIPLE_SYMBOL_SPACES'
+ Define this macro if in some cases global symbols from one
+ translation unit may not be bound to undefined symbols in another
+ translation unit without user intervention. For instance, under
+ Microsoft Windows symbols must be explicitly imported from shared
+ libraries (DLLs).
+
+`MD_ASM_CLOBBERS (CLOBBERS)'
+ A C statement that adds to CLOBBERS `STRING_CST' trees for any
+ hard regs the port wishes to automatically clobber for all asms.
+
+`MAX_INTEGER_COMPUTATION_MODE'
+ Define this to the largest integer machine mode which can be used
+ for operations other than load, store and copy operations.
+
+ You need only define this macro if the target holds values larger
+ than `word_mode' in general purpose registers. Most targets
+ should not define this macro.
+
+`MATH_LIBRARY'
+ Define this macro as a C string constant for the linker argument
+ to link in the system math library, or `""' if the target does not
+ have a separate math library.
+
+ You need only define this macro if the default of `"-lm"' is wrong.
+
+`LIBRARY_PATH_ENV'
+ Define this macro as a C string constant for the environment
+ variable that specifies where the linker should look for libraries.
+
+ You need only define this macro if the default of `"LIBRARY_PATH"'
+ is wrong.
+
+`TARGET_HAS_F_SETLKW'
+ Define this macro if the target supports file locking with fcntl /
+ F_SETLKW. Note that this functionality is part of POSIX.
+ Defining `TARGET_HAS_F_SETLKW' will enable the test coverage code
+ to use file locking when exiting a program, which avoids race
+ conditions if the program has forked.
+
+`MAX_CONDITIONAL_EXECUTE'
+ A C expression for the maximum number of instructions to execute
+ via conditional execution instructions instead of a branch. A
+ value of `BRANCH_COST'+1 is the default if the machine does not
+ use cc0, and 1 if it does use cc0.
+
+`IFCVT_MODIFY_TESTS'
+ A C expression to modify the tests in `TRUE_EXPR', and
+ `FALSE_EXPR' for use in converting insns in `TEST_BB', `THEN_BB',
+ `ELSE_BB', and `JOIN_BB' basic blocks to conditional execution.
+ Set either `TRUE_EXPR' or `FALSE_EXPR' to a null pointer if the
+ tests cannot be converted.
+
+`IFCVT_MODIFY_INSN'
+ A C expression to modify the `PATTERN' of an `INSN' that is to be
+ converted to conditional execution format.
+
+`IFCVT_MODIFY_FINAL'
+ A C expression to perform any final machine dependent
+ modifications in converting code to conditional execution in the
+ basic blocks `TEST_BB', `THEN_BB', `ELSE_BB', and `JOIN_BB'.
+
+`IFCVT_MODIFY_CANCEL'
+ A C expression to cancel any machine dependent modifications in
+ converting code to conditional execution in the basic blocks
+ `TEST_BB', `THEN_BB', `ELSE_BB', and `JOIN_BB'.
+
+ -- Target Hook: void TARGET_INIT_BUILTINS ()
+ Define this hook if you have any machine-specific built-in
+ functions that need to be defined. It should be a function that
+ performs the necessary setup.
+
+ Machine specific built-in functions can be useful to expand
+ special machine instructions that would otherwise not normally be
+ generated because they have no equivalent in the source language
+ (for example, SIMD vector instructions or prefetch instructions).
+
+ To create a built-in function, call the function `builtin_function'
+ which is defined by the language front end. You can use any type
+ nodes set up by `build_common_tree_nodes' and
+ `build_common_tree_nodes_2'; only language front ends that use
+ those two functions will call `TARGET_INIT_BUILTINS'.
+
+ -- Target Hook: rtx TARGET_EXPAND_BUILTIN (tree EXP, rtx TARGET, rtx
+ SUBTARGET, enum machine_mode MODE, int IGNORE)
+ Expand a call to a machine specific built-in function that was set
+ up by `TARGET_INIT_BUILTINS'. EXP is the expression for the
+ function call; the result should go to TARGET if that is
+ convenient, and have mode MODE if that is convenient. SUBTARGET
+ may be used as the target for computing one of EXP's operands.
+ IGNORE is nonzero if the value is to be ignored. This function
+ should return the result of the call to the built-in function.
+
+`MD_CAN_REDIRECT_BRANCH(BRANCH1, BRANCH2)'
+ Take a branch insn in BRANCH1 and another in BRANCH2. Return true
+ if redirecting BRANCH1 to the destination of BRANCH2 is possible.
+
+ On some targets, branches may have a limited range. Optimizing the
+ filling of delay slots can result in branches being redirected,
+ and this may in turn cause a branch offset to overflow.
+
+`ALLOCATE_INITIAL_VALUE(HARD_REG)'
+ When the initial value of a hard register has been copied in a
+ pseudo register, it is often not necessary to actually allocate
+ another register to this pseudo register, because the original
+ hard register or a stack slot it has been saved into can be used.
+ `ALLOCATE_INITIAL_VALUE', if defined, is called at the start of
+ register allocation once for each hard register that had its
+ initial value copied by using `get_func_hard_reg_initial_val' or
+ `get_hard_reg_initial_val'. Possible values are `NULL_RTX', if
+ you don't want to do any special allocation, a `REG' rtx--that
+ would typically be the hard register itself, if it is known not to
+ be clobbered--or a `MEM'. If you are returning a `MEM', this is
+ only a hint for the allocator; it might decide to use another
+ register anyways. You may use `current_function_leaf_function' in
+ the definition of the macro, functions that use `REG_N_SETS', to
+ determine if the hard register in question will not be clobbered.
+
+`TARGET_OBJECT_SUFFIX'
+ Define this macro to be a C string representing the suffix for
+ object files on your target machine. If you do not define this
+ macro, GCC will use `.o' as the suffix for object files.
+
+`TARGET_EXECUTABLE_SUFFIX'
+ Define this macro to be a C string representing the suffix to be
+ automatically added to executable files on your target machine.
+ If you do not define this macro, GCC will use the null string as
+ the suffix for executable files.
+
+`COLLECT_EXPORT_LIST'
+ If defined, `collect2' will scan the individual object files
+ specified on its command line and create an export list for the
+ linker. Define this macro for systems like AIX, where the linker
+ discards object files that are not referenced from `main' and uses
+ export lists.
+
+
+ -- Target Hook: bool TARGET_CANNOT_MODIFY_JUMPS_P (void)
+ This target hook returns `true' past the point in which new jump
+ instructions could be created. On machines that require a
+ register for every jump such as the SHmedia ISA of SH5, this point
+ would typically be reload, so this target hook should be defined
+ to a function such as:
+
+ static bool
+ cannot_modify_jumps_past_reload_p ()
+ {
+ return (reload_completed || reload_in_progress);
+ }
-`DECL_THUNK_P'
- This predicate holds if the function is a thunk.
-
- These functions represent stub code that adjusts the `this' pointer
- and then jumps to another function. When the jumped-to function
- returns, control is transferred directly to the caller, without
- returning to the thunk. The first parameter to the thunk is
- always the `this' pointer; the thunk should add `THUNK_DELTA' to
- this value. (The `THUNK_DELTA' is an `int', not an `INTEGER_CST'.)
-
- Then, if `THUNK_VCALL_OFFSET' (an `INTEGER_CST') is nonzero the
- adjusted `this' pointer must be adjusted again. The complete
- calculation is given by the following pseudo-code:
-
- this += THUNK_DELTA
- if (THUNK_VCALL_OFFSET)
- this += (*((ptrdiff_t **) this))[THUNK_VCALL_OFFSET]
-
- Finally, the thunk should jump to the location given by
- `DECL_INITIAL'; this will always be an expression for the address
- of a function.
-
-`DECL_NON_THUNK_FUNCTION_P'
- This predicate holds if the function is _not_ a thunk function.
-
-`GLOBAL_INIT_PRIORITY'
- If either `DECL_GLOBAL_CTOR_P' or `DECL_GLOBAL_DTOR_P' holds, then
- this gives the initialization priority for the function. The
- linker will arrange that all functions for which
- `DECL_GLOBAL_CTOR_P' holds are run in increasing order of priority
- before `main' is called. When the program exits, all functions for
- which `DECL_GLOBAL_DTOR_P' holds are run in the reverse order.
-
-`DECL_ARTIFICIAL'
- This macro holds if the function was implicitly generated by the
- compiler, rather than explicitly declared. In addition to
- implicitly generated class member functions, this macro holds for
- the special functions created to implement static initialization
- and destruction, to compute run-time type information, and so
- forth.
-
-`DECL_ARGUMENTS'
- This macro returns the `PARM_DECL' for the first argument to the
- function. Subsequent `PARM_DECL' nodes can be obtained by
- following the `TREE_CHAIN' links.
-
-`DECL_RESULT'
- This macro returns the `RESULT_DECL' for the function.
-
-`TREE_TYPE'
- This macro returns the `FUNCTION_TYPE' or `METHOD_TYPE' for the
- function.
+\1f
+File: gccint.info, Node: Host Config, Next: Fragments, Prev: Target Macros, Up: Top
+
+11 Host Configuration Headers
+*****************************
+
+Host configuration headers contain macro definitions that describe the
+machine and system on which the compiler is running. They are usually
+unnecessary. Most of the things GCC needs to know about the host
+system can be deduced by the `configure' script.
+
+ If your host does need a special configuration header, it should be
+named `xm-MACHINE.h', where MACHINE is a short mnemonic for the
+machine. Here are some macros which this header can define.
+
+`VMS'
+ Define this macro if the host system is VMS.
+
+`FATAL_EXIT_CODE'
+ A C expression for the status code to be returned when the compiler
+ exits after serious errors. The default is the system-provided
+ macro `EXIT_FAILURE', or `1' if the system doesn't define that
+ macro. Define this macro only if these defaults are incorrect.
+
+`SUCCESS_EXIT_CODE'
+ A C expression for the status code to be returned when the compiler
+ exits without serious errors. (Warnings are not serious errors.)
+ The default is the system-provided macro `EXIT_SUCCESS', or `0' if
+ the system doesn't define that macro. Define this macro only if
+ these defaults are incorrect.
+
+`USE_C_ALLOCA'
+ Define this macro if GCC should use the C implementation of
+ `alloca' provided by `libiberty.a'. This only affects how some
+ parts of the compiler itself allocate memory. It does not change
+ code generation.
+
+ When GCC is built with a compiler other than itself, the C `alloca'
+ is always used. This is because most other implementations have
+ serious bugs. You should define this macro only on a system where
+ no stack-based `alloca' can possibly work. For instance, if a
+ system has a small limit on the size of the stack, GCC's builtin
+ `alloca' will not work reliably.
+
+`HAVE_DOS_BASED_FILE_SYSTEM'
+ Define this macro if the host file system obeys the semantics
+ defined by MS-DOS instead of Unix. DOS file systems are case
+ insensitive, file specifications may begin with a drive letter,
+ and both forward slash and backslash (`/' and `\') are directory
+ separators. If you define this macro, you probably need to define
+ the next three macros too.
+
+`PATH_SEPARATOR'
+ If defined, this macro should expand to a character constant
+ specifying the separator for elements of search paths. The
+ default value is a colon (`:'). DOS-based systems usually use
+ semicolon (`;').
+
+`DIR_SEPARATOR'
+`DIR_SEPARATOR_2'
+ If defined, these macros expand to character constants specifying
+ separators for directory names within a file specification. They
+ are used somewhat inconsistently throughout the compiler. If your
+ system behaves like Unix (only forward slash separates pathnames),
+ define neither of them. If your system behaves like DOS (both
+ forward and backward slash can be used), define `DIR_SEPARATOR' to
+ `/' and `DIR_SEPARATOR_2' to `\'.
+
+`HOST_OBJECT_SUFFIX'
+ Define this macro to be a C string representing the suffix for
+ object files on your host machine. If you do not define this
+ macro, GCC will use `.o' as the suffix for object files.
+
+`HOST_EXECUTABLE_SUFFIX'
+ Define this macro to be a C string representing the suffix for
+ executable files on your host machine. If you do not define this
+ macro, GCC will use the null string as the suffix for executable
+ files.
+
+`HOST_BIT_BUCKET'
+ A pathname defined by the host operating system, which can be
+ opened as a file and written to, but all the information written
+ is discarded. This is commonly known as a "bit bucket" or "null
+ device". If you do not define this macro, GCC will use
+ `/dev/null' as the bit bucket. If the host does not support a bit
+ bucket, define this macro to an invalid filename.
+
+`COLLECT2_HOST_INITIALIZATION'
+ If defined, a C statement (sans semicolon) that performs
+ host-dependent initialization when `collect2' is being initialized.
+
+`GCC_DRIVER_HOST_INITIALIZATION'
+ If defined, a C statement (sans semicolon) that performs
+ host-dependent initialization when a compilation driver is being
+ initialized.
+
+`UPDATE_PATH_HOST_CANONICALIZE (PATH)'
+ If defined, a C statement (sans semicolon) that performs
+ host-dependent canonicalization when a path used in a compilation
+ driver or preprocessor is canonicalized. PATH is a malloc-ed path
+ to be canonicalized. If the C statement does canonicalize PATH
+ into a different buffer, the old path should be freed and the new
+ buffer should have been allocated with malloc.
+
+`DUMPFILE_FORMAT'
+ Define this macro to be a C string representing the format to use
+ for constructing the index part of debugging dump file names. The
+ resultant string must fit in fifteen bytes. The full filename
+ will be the concatenation of: the prefix of the assembler file
+ name, the string resulting from applying this format to an index
+ number, and a string unique to each dump file kind, e.g. `rtl'.
+
+ If you do not define this macro, GCC will use `.%02d.'. You should
+ define this macro if using the default will create an invalid file
+ name.
+
+`SMALL_ARG_MAX'
+ Define this macro if the host system has a small limit on the total
+ size of an argument vector. This causes the driver to take more
+ care not to pass unnecessary arguments to subprocesses.
+
+ In addition, if `configure' generates an incorrect definition of any
+of the macros in `auto-host.h', you can override that definition in a
+host configuration header. If you need to do this, first see if it is
+possible to fix `configure'.
+
+ If you need to define only a few of these macros, and they have
+simple definitions, consider using the `xm_defines' variable in your
+`config.gcc' entry instead of creating a host configuration header.
+*Note System Config::.
+
+\1f
+File: gccint.info, Node: Fragments, Next: Collect2, Prev: Host Config, Up: Top
+
+12 Makefile Fragments
+*********************
+
+When you configure GCC using the `configure' script, it will construct
+the file `Makefile' from the template file `Makefile.in'. When it does
+this, it can incorporate makefile fragments from the `config'
+directory. These are used to set Makefile parameters that are not
+amenable to being calculated by autoconf. The list of fragments to
+incorporate is set by `config.gcc'; *Note System Config::.
+
+ Fragments are named either `t-TARGET' or `x-HOST', depending on
+whether they are relevant to configuring GCC to produce code for a
+particular target, or to configuring GCC to run on a particular host.
+Here TARGET and HOST are mnemonics which usually have some relationship
+to the canonical system name, but no formal connection.
+
+ If these files do not exist, it means nothing needs to be added for a
+given target or host. Most targets need a few `t-TARGET' fragments,
+but needing `x-HOST' fragments is rare.
+
+* Menu:
+
+* Target Fragment:: Writing `t-TARGET' files.
+* Host Fragment:: Writing `x-HOST' files.
+
+\1f
+File: gccint.info, Node: Target Fragment, Next: Host Fragment, Up: Fragments
+
+12.1 Target Makefile Fragments
+==============================
+
+Target makefile fragments can set these Makefile variables.
+
+`LIBGCC2_CFLAGS'
+ Compiler flags to use when compiling `libgcc2.c'.
+
+`LIB2FUNCS_EXTRA'
+ A list of source file names to be compiled or assembled and
+ inserted into `libgcc.a'.
+
+`Floating Point Emulation'
+ To have GCC include software floating point libraries in `libgcc.a'
+ define `FPBIT' and `DPBIT' along with a few rules as follows:
+ # We want fine grained libraries, so use the new code
+ # to build the floating point emulation libraries.
+ FPBIT = fp-bit.c
+ DPBIT = dp-bit.c
+
+
+ fp-bit.c: $(srcdir)/config/fp-bit.c
+ echo '#define FLOAT' > fp-bit.c
+ cat $(srcdir)/config/fp-bit.c >> fp-bit.c
+
+ dp-bit.c: $(srcdir)/config/fp-bit.c
+ cat $(srcdir)/config/fp-bit.c > dp-bit.c
+
+ You may need to provide additional #defines at the beginning of
+ `fp-bit.c' and `dp-bit.c' to control target endianness and other
+ options.
+
+`CRTSTUFF_T_CFLAGS'
+ Special flags used when compiling `crtstuff.c'. *Note
+ Initialization::.
+
+`CRTSTUFF_T_CFLAGS_S'
+ Special flags used when compiling `crtstuff.c' for shared linking.
+ Used if you use `crtbeginS.o' and `crtendS.o' in `EXTRA-PARTS'.
+ *Note Initialization::.
+
+`MULTILIB_OPTIONS'
+ For some targets, invoking GCC in different ways produces objects
+ that can not be linked together. For example, for some targets GCC
+ produces both big and little endian code. For these targets, you
+ must arrange for multiple versions of `libgcc.a' to be compiled,
+ one for each set of incompatible options. When GCC invokes the
+ linker, it arranges to link in the right version of `libgcc.a',
+ based on the command line options used.
+
+ The `MULTILIB_OPTIONS' macro lists the set of options for which
+ special versions of `libgcc.a' must be built. Write options that
+ are mutually incompatible side by side, separated by a slash.
+ Write options that may be used together separated by a space. The
+ build procedure will build all combinations of compatible options.
+
+ For example, if you set `MULTILIB_OPTIONS' to `m68000/m68020
+ msoft-float', `Makefile' will build special versions of `libgcc.a'
+ using the following sets of options: `-m68000', `-m68020',
+ `-msoft-float', `-m68000 -msoft-float', and `-m68020 -msoft-float'.
+
+`MULTILIB_DIRNAMES'
+ If `MULTILIB_OPTIONS' is used, this variable specifies the
+ directory names that should be used to hold the various libraries.
+ Write one element in `MULTILIB_DIRNAMES' for each element in
+ `MULTILIB_OPTIONS'. If `MULTILIB_DIRNAMES' is not used, the
+ default value will be `MULTILIB_OPTIONS', with all slashes treated
+ as spaces.
+
+ For example, if `MULTILIB_OPTIONS' is set to `m68000/m68020
+ msoft-float', then the default value of `MULTILIB_DIRNAMES' is
+ `m68000 m68020 msoft-float'. You may specify a different value if
+ you desire a different set of directory names.
+
+`MULTILIB_MATCHES'
+ Sometimes the same option may be written in two different ways.
+ If an option is listed in `MULTILIB_OPTIONS', GCC needs to know
+ about any synonyms. In that case, set `MULTILIB_MATCHES' to a
+ list of items of the form `option=option' to describe all relevant
+ synonyms. For example, `m68000=mc68000 m68020=mc68020'.
+
+`MULTILIB_EXCEPTIONS'
+ Sometimes when there are multiple sets of `MULTILIB_OPTIONS' being
+ specified, there are combinations that should not be built. In
+ that case, set `MULTILIB_EXCEPTIONS' to be all of the switch
+ exceptions in shell case syntax that should not be built.
+
+ For example, in the PowerPC embedded ABI support, it is not
+ desirable to build libraries compiled with the `-mcall-aix' option
+ and either of the `-fleading-underscore' or `-mlittle' options at
+ the same time. Therefore `MULTILIB_EXCEPTIONS' is set to
+ *mcall-aix/*fleading-underscore* *mlittle/*mcall-aix*
+
+`MULTILIB_EXTRA_OPTS'
+ Sometimes it is desirable that when building multiple versions of
+ `libgcc.a' certain options should always be passed on to the
+ compiler. In that case, set `MULTILIB_EXTRA_OPTS' to be the list
+ of options to be used for all builds.
+
+\1f
+File: gccint.info, Node: Host Fragment, Prev: Target Fragment, Up: Fragments
+
+12.2 Host Makefile Fragments
+============================
+
+The use of `x-HOST' fragments is discouraged. You should do so only if
+there is no other mechanism to get the behavior desired. Host
+fragments should never forcibly override variables set by the configure
+script, as they may have been adjusted by the user.
+
+ Variables provided for host fragments to set include:
+
+`X_CFLAGS'
+`X_CPPFLAGS'
+ These are extra flags to pass to the C compiler and preprocessor,
+ respectively. They are used both when building GCC, and when
+ compiling things with the just-built GCC.
+
+`XCFLAGS'
+ These are extra flags to use when building the compiler. They are
+ not used when compiling `libgcc.a'. However, they _are_ used when
+ recompiling the compiler with itself in later stages of a
+ bootstrap.
-`TYPE_RAISES_EXCEPTIONS'
- This macro returns the list of exceptions that a (member-)function
- can raise. The returned list, if non `NULL', is comprised of nodes
- whose `TREE_VALUE' represents a type.
+`BOOT_LDFLAGS'
+ Flags to be passed to the linker when recompiling the compiler with
+ itself in later stages of a bootstrap. You might need to use this
+ if, for instance, one of the front ends needs more text space than
+ the linker provides by default.
-`TYPE_NOTHROW_P'
- This predicate holds when the exception-specification of its
- arguments if of the form ``()''.
+`EXTRA_PROGRAMS'
+ A list of additional programs required to use the compiler on this
+ host, which should be compiled with GCC and installed alongside
+ the front ends. If you set this variable, you must also provide
+ rules to build the extra programs.
-`DECL_ARRAY_DELETE_OPERATOR_P'
- This predicate holds if the function an overloaded `operator
- delete[]'.
+\1f
+File: gccint.info, Node: Collect2, Next: Header Dirs, Prev: Fragments, Up: Top
+
+13 `collect2'
+*************
+
+GNU CC uses a utility called `collect2' on nearly all systems to arrange
+to call various initialization functions at start time.
+
+ The program `collect2' works by linking the program once and looking
+through the linker output file for symbols with particular names
+indicating they are constructor functions. If it finds any, it creates
+a new temporary `.c' file containing a table of them, compiles it, and
+links the program a second time including that file.
+
+ The actual calls to the constructors are carried out by a subroutine
+called `__main', which is called (automatically) at the beginning of
+the body of `main' (provided `main' was compiled with GNU CC). Calling
+`__main' is necessary, even when compiling C code, to allow linking C
+and C++ object code together. (If you use `-nostdlib', you get an
+unresolved reference to `__main', since it's defined in the standard
+GCC library. Include `-lgcc' at the end of your compiler command line
+to resolve this reference.)
+
+ The program `collect2' is installed as `ld' in the directory where
+the passes of the compiler are installed. When `collect2' needs to
+find the _real_ `ld', it tries the following file names:
+
+ * `real-ld' in the directories listed in the compiler's search
+ directories.
+
+ * `real-ld' in the directories listed in the environment variable
+ `PATH'.
+
+ * The file specified in the `REAL_LD_FILE_NAME' configuration macro,
+ if specified.
+
+ * `ld' in the compiler's search directories, except that `collect2'
+ will not execute itself recursively.
+
+ * `ld' in `PATH'.
+
+ "The compiler's search directories" means all the directories where
+`gcc' searches for passes of the compiler. This includes directories
+that you specify with `-B'.
+
+ Cross-compilers search a little differently:
+
+ * `real-ld' in the compiler's search directories.
+
+ * `TARGET-real-ld' in `PATH'.
+
+ * The file specified in the `REAL_LD_FILE_NAME' configuration macro,
+ if specified.
+
+ * `ld' in the compiler's search directories.
+
+ * `TARGET-ld' in `PATH'.
+
+ `collect2' explicitly avoids running `ld' using the file name under
+which `collect2' itself was invoked. In fact, it remembers up a list
+of such names--in case one copy of `collect2' finds another copy (or
+version) of `collect2' installed as `ld' in a second place in the
+search path.
+
+ `collect2' searches for the utilities `nm' and `strip' using the
+same algorithm as above for `ld'.
+
+\1f
+File: gccint.info, Node: Header Dirs, Next: Funding, Prev: Collect2, Up: Top
+
+14 Standard Header File Directories
+***********************************
+
+`GCC_INCLUDE_DIR' means the same thing for native and cross. It is
+where GNU CC stores its private include files, and also where GNU CC
+stores the fixed include files. A cross compiled GNU CC runs
+`fixincludes' on the header files in `$(tooldir)/include'. (If the
+cross compilation header files need to be fixed, they must be installed
+before GNU CC is built. If the cross compilation header files are
+already suitable for ISO C and GNU CC, nothing special need be done).
+
+ `GPLUSPLUS_INCLUDE_DIR' means the same thing for native and cross.
+It is where `g++' looks first for header files. The C++ library
+installs only target independent header files in that directory.
+
+ `LOCAL_INCLUDE_DIR' is used only by native compilers. GNU CC
+doesn't install anything there. It is normally `/usr/local/include'.
+This is where local additions to a packaged system should place header
+files.
+
+ `CROSS_INCLUDE_DIR' is used only by cross compilers. GNU CC doesn't
+install anything there.
+
+ `TOOL_INCLUDE_DIR' is used for both native and cross compilers. It
+is the place for other packages to install header files that GNU CC will
+use. For a cross-compiler, this is the equivalent of `/usr/include'.
+When you build a cross-compiler, `fixincludes' processes any header
+files in this directory.
+
+\1f
+File: gccint.info, Node: Funding, Next: GNU Project, Prev: Header Dirs, Up: Top
+
+Funding Free Software
+*********************
+
+If you want to have more free software a few years from now, it makes
+sense for you to help encourage people to contribute funds for its
+development. The most effective approach known is to encourage
+commercial redistributors to donate.
+
+ Users of free software systems can boost the pace of development by
+encouraging for-a-fee distributors to donate part of their selling price
+to free software developers--the Free Software Foundation, and others.
+
+ The way to convince distributors to do this is to demand it and
+expect it from them. So when you compare distributors, judge them
+partly by how much they give to free software development. Show
+distributors they must compete to be the one who gives the most.
+
+ To make this approach work, you must insist on numbers that you can
+compare, such as, "We will donate ten dollars to the Frobnitz project
+for each disk sold." Don't be satisfied with a vague promise, such as
+"A portion of the profits are donated," since it doesn't give a basis
+for comparison.
+
+ Even a precise fraction "of the profits from this disk" is not very
+meaningful, since creative accounting and unrelated business decisions
+can greatly alter what fraction of the sales price counts as profit.
+If the price you pay is $50, ten percent of the profit is probably less
+than a dollar; it might be a few cents, or nothing at all.
+
+ Some redistributors do development work themselves. This is useful
+too; but to keep everyone honest, you need to inquire how much they do,
+and what kind. Some kinds of development make much more long-term
+difference than others. For example, maintaining a separate version of
+a program contributes very little; maintaining the standard version of a
+program for the whole community contributes much. Easy new ports
+contribute little, since someone else would surely do them; difficult
+ports such as adding a new CPU to the GNU Compiler Collection
+contribute more; major new features or packages contribute the most.
+
+ By establishing the idea that supporting further development is "the
+proper thing to do" when distributing free software for a fee, we can
+assure a steady flow of resources into making more free software.
+
+ Copyright (C) 1994 Free Software Foundation, Inc.
+ Verbatim copying and redistribution of this section is permitted
+ without royalty; alteration is not permitted.
+
+\1f
+File: gccint.info, Node: GNU Project, Next: Copying, Prev: Funding, Up: Top
+
+The GNU Project and GNU/Linux
+*****************************
+
+The GNU Project was launched in 1984 to develop a complete Unix-like
+operating system which is free software: the GNU system. (GNU is a
+recursive acronym for "GNU's Not Unix"; it is pronounced "guh-NEW".)
+Variants of the GNU operating system, which use the kernel Linux, are
+now widely used; though these systems are often referred to as "Linux",
+they are more accurately called GNU/Linux systems.
+
+ For more information, see:
+ `http://www.gnu.org/'
+ `http://www.gnu.org/gnu/linux-and-gnu.html'
+
+\1f
+File: gccint.info, Node: Copying, Next: GNU Free Documentation License, Prev: GNU Project, Up: Top
+
+GNU GENERAL PUBLIC LICENSE
+**************************
+
+ Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+ 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+Preamble
+========
+
+The licenses for most software are designed to take away your freedom
+to share and change it. By contrast, the GNU General Public License is
+intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users. This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it. (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.) You can apply it to
+your programs, too.
+
+ When we speak of free software, we are referring to freedom, not
+price. Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it in
+new free programs; and that you know you can do these things.
+
+ To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+ For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have. You must make sure that they, too, receive or can get the
+source code. And you must show them these terms so they know their
+rights.
+
+ We protect your rights with two steps: (1) copyright the software,
+and (2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+ Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software. If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+ Finally, any free program is threatened constantly by software
+patents. We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary. To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+ The precise terms and conditions for copying, distribution and
+modification follow.
+
+ TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+ 0. This License applies to any program or other work which contains a
+ notice placed by the copyright holder saying it may be distributed
+ under the terms of this General Public License. The "Program",
+ below, refers to any such program or work, and a "work based on
+ the Program" means either the Program or any derivative work under
+ copyright law: that is to say, a work containing the Program or a
+ portion of it, either verbatim or with modifications and/or
+ translated into another language. (Hereinafter, translation is
+ included without limitation in the term "modification".) Each
+ licensee is addressed as "you".
+
+ Activities other than copying, distribution and modification are
+ not covered by this License; they are outside its scope. The act
+ of running the Program is not restricted, and the output from the
+ Program is covered only if its contents constitute a work based on
+ the Program (independent of having been made by running the
+ Program). Whether that is true depends on what the Program does.
+
+ 1. You may copy and distribute verbatim copies of the Program's
+ source code as you receive it, in any medium, provided that you
+ conspicuously and appropriately publish on each copy an appropriate
+ copyright notice and disclaimer of warranty; keep intact all the
+ notices that refer to this License and to the absence of any
+ warranty; and give any other recipients of the Program a copy of
+ this License along with the Program.
+
+ You may charge a fee for the physical act of transferring a copy,
+ and you may at your option offer warranty protection in exchange
+ for a fee.
+
+ 2. You may modify your copy or copies of the Program or any portion
+ of it, thus forming a work based on the Program, and copy and
+ distribute such modifications or work under the terms of Section 1
+ above, provided that you also meet all of these conditions:
+
+ a. You must cause the modified files to carry prominent notices
+ stating that you changed the files and the date of any change.
+
+ b. You must cause any work that you distribute or publish, that
+ in whole or in part contains or is derived from the Program
+ or any part thereof, to be licensed as a whole at no charge
+ to all third parties under the terms of this License.
+
+ c. If the modified program normally reads commands interactively
+ when run, you must cause it, when started running for such
+ interactive use in the most ordinary way, to print or display
+ an announcement including an appropriate copyright notice and
+ a notice that there is no warranty (or else, saying that you
+ provide a warranty) and that users may redistribute the
+ program under these conditions, and telling the user how to
+ view a copy of this License. (Exception: if the Program
+ itself is interactive but does not normally print such an
+ announcement, your work based on the Program is not required
+ to print an announcement.)
+
+ These requirements apply to the modified work as a whole. If
+ identifiable sections of that work are not derived from the
+ Program, and can be reasonably considered independent and separate
+ works in themselves, then this License, and its terms, do not
+ apply to those sections when you distribute them as separate
+ works. But when you distribute the same sections as part of a
+ whole which is a work based on the Program, the distribution of
+ the whole must be on the terms of this License, whose permissions
+ for other licensees extend to the entire whole, and thus to each
+ and every part regardless of who wrote it.
+
+ Thus, it is not the intent of this section to claim rights or
+ contest your rights to work written entirely by you; rather, the
+ intent is to exercise the right to control the distribution of
+ derivative or collective works based on the Program.
+
+ In addition, mere aggregation of another work not based on the
+ Program with the Program (or with a work based on the Program) on
+ a volume of a storage or distribution medium does not bring the
+ other work under the scope of this License.
+
+ 3. You may copy and distribute the Program (or a work based on it,
+ under Section 2) in object code or executable form under the terms
+ of Sections 1 and 2 above provided that you also do one of the
+ following:
+
+ a. Accompany it with the complete corresponding machine-readable
+ source code, which must be distributed under the terms of
+ Sections 1 and 2 above on a medium customarily used for
+ software interchange; or,
+
+ b. Accompany it with a written offer, valid for at least three
+ years, to give any third party, for a charge no more than your
+ cost of physically performing source distribution, a complete
+ machine-readable copy of the corresponding source code, to be
+ distributed under the terms of Sections 1 and 2 above on a
+ medium customarily used for software interchange; or,
+
+ c. Accompany it with the information you received as to the offer
+ to distribute corresponding source code. (This alternative is
+ allowed only for noncommercial distribution and only if you
+ received the program in object code or executable form with
+ such an offer, in accord with Subsection b above.)
+
+ The source code for a work means the preferred form of the work for
+ making modifications to it. For an executable work, complete
+ source code means all the source code for all modules it contains,
+ plus any associated interface definition files, plus the scripts
+ used to control compilation and installation of the executable.
+ However, as a special exception, the source code distributed need
+ not include anything that is normally distributed (in either
+ source or binary form) with the major components (compiler,
+ kernel, and so on) of the operating system on which the executable
+ runs, unless that component itself accompanies the executable.
+
+ If distribution of executable or object code is made by offering
+ access to copy from a designated place, then offering equivalent
+ access to copy the source code from the same place counts as
+ distribution of the source code, even though third parties are not
+ compelled to copy the source along with the object code.
+
+ 4. You may not copy, modify, sublicense, or distribute the Program
+ except as expressly provided under this License. Any attempt
+ otherwise to copy, modify, sublicense or distribute the Program is
+ void, and will automatically terminate your rights under this
+ License. However, parties who have received copies, or rights,
+ from you under this License will not have their licenses
+ terminated so long as such parties remain in full compliance.
+
+ 5. You are not required to accept this License, since you have not
+ signed it. However, nothing else grants you permission to modify
+ or distribute the Program or its derivative works. These actions
+ are prohibited by law if you do not accept this License.
+ Therefore, by modifying or distributing the Program (or any work
+ based on the Program), you indicate your acceptance of this
+ License to do so, and all its terms and conditions for copying,
+ distributing or modifying the Program or works based on it.
+
+ 6. Each time you redistribute the Program (or any work based on the
+ Program), the recipient automatically receives a license from the
+ original licensor to copy, distribute or modify the Program
+ subject to these terms and conditions. You may not impose any
+ further restrictions on the recipients' exercise of the rights
+ granted herein. You are not responsible for enforcing compliance
+ by third parties to this License.
+
+ 7. If, as a consequence of a court judgment or allegation of patent
+ infringement or for any other reason (not limited to patent
+ issues), conditions are imposed on you (whether by court order,
+ agreement or otherwise) that contradict the conditions of this
+ License, they do not excuse you from the conditions of this
+ License. If you cannot distribute so as to satisfy simultaneously
+ your obligations under this License and any other pertinent
+ obligations, then as a consequence you may not distribute the
+ Program at all. For example, if a patent license would not permit
+ royalty-free redistribution of the Program by all those who
+ receive copies directly or indirectly through you, then the only
+ way you could satisfy both it and this License would be to refrain
+ entirely from distribution of the Program.
+
+ If any portion of this section is held invalid or unenforceable
+ under any particular circumstance, the balance of the section is
+ intended to apply and the section as a whole is intended to apply
+ in other circumstances.
+
+ It is not the purpose of this section to induce you to infringe any
+ patents or other property right claims or to contest validity of
+ any such claims; this section has the sole purpose of protecting
+ the integrity of the free software distribution system, which is
+ implemented by public license practices. Many people have made
+ generous contributions to the wide range of software distributed
+ through that system in reliance on consistent application of that
+ system; it is up to the author/donor to decide if he or she is
+ willing to distribute software through any other system and a
+ licensee cannot impose that choice.
+
+ This section is intended to make thoroughly clear what is believed
+ to be a consequence of the rest of this License.
+
+ 8. If the distribution and/or use of the Program is restricted in
+ certain countries either by patents or by copyrighted interfaces,
+ the original copyright holder who places the Program under this
+ License may add an explicit geographical distribution limitation
+ excluding those countries, so that distribution is permitted only
+ in or among countries not thus excluded. In such case, this
+ License incorporates the limitation as if written in the body of
+ this License.
+
+ 9. The Free Software Foundation may publish revised and/or new
+ versions of the General Public License from time to time. Such
+ new versions will be similar in spirit to the present version, but
+ may differ in detail to address new problems or concerns.
+
+ Each version is given a distinguishing version number. If the
+ Program specifies a version number of this License which applies
+ to it and "any later version", you have the option of following
+ the terms and conditions either of that version or of any later
+ version published by the Free Software Foundation. If the Program
+ does not specify a version number of this License, you may choose
+ any version ever published by the Free Software Foundation.
+
+ 10. If you wish to incorporate parts of the Program into other free
+ programs whose distribution conditions are different, write to the
+ author to ask for permission. For software which is copyrighted
+ by the Free Software Foundation, write to the Free Software
+ Foundation; we sometimes make exceptions for this. Our decision
+ will be guided by the two goals of preserving the free status of
+ all derivatives of our free software and of promoting the sharing
+ and reuse of software generally.
+
+ NO WARRANTY
+ 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO
+ WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE
+ LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+ HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT
+ WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT
+ NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE
+ QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
+ PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY
+ SERVICING, REPAIR OR CORRECTION.
+
+ 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN
+ WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY
+ MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE
+ LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL,
+ INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
+ INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+ DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU
+ OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY
+ OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN
+ ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+
+ END OF TERMS AND CONDITIONS
+How to Apply These Terms to Your New Programs
+=============================================
+
+If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these
+terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+ ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES.
+ Copyright (C) YEAR NAME OF AUTHOR
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA.
+
+ Also add information on how to contact you by electronic and paper
+mail.
+
+ If the program is interactive, make it output a short notice like
+this when it starts in an interactive mode:
+
+ Gnomovision version 69, Copyright (C) YEAR NAME OF AUTHOR
+ Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
+ type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+ The hypothetical commands `show w' and `show c' should show the
+appropriate parts of the General Public License. Of course, the
+commands you use may be called something other than `show w' and `show
+c'; they could even be mouse-clicks or menu items--whatever suits your
+program.
+
+ You should also get your employer (if you work as a programmer) or
+your school, if any, to sign a "copyright disclaimer" for the program,
+if necessary. Here is a sample; alter the names:
+
+ Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+ `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+ SIGNATURE OF TY COON, 1 April 1989
+ Ty Coon, President of Vice
+
+ This General Public License does not permit incorporating your
+program into proprietary programs. If your program is a subroutine
+library, you may consider it more useful to permit linking proprietary
+applications with the library. If this is what you want to do, use the
+GNU Library General Public License instead of this License.
-This is doc/gccint.info, produced by makeinfo version 4.5 from
+This is doc/gccint.info, produced by makeinfo version 4.11 from
doc/gccint.texi.
INFO-DIR-SECTION Programming
funds for GNU development.
\1f
-File: gccint.info, Node: Function Bodies, Prev: Function Basics, Up: Functions
-
-Function Bodies
----------------
-
- A function that has a definition in the current translation unit will
-have a non-`NULL' `DECL_INITIAL'. However, back ends should not make
-use of the particular value given by `DECL_INITIAL'.
-
- The `DECL_SAVED_TREE' macro will give the complete body of the
-function. This node will usually be a `COMPOUND_STMT' representing the
-outermost block of the function, but it may also be a `TRY_BLOCK', a
-`RETURN_INIT', or any other valid statement.
-
-Statements
-..........
-
- There are tree nodes corresponding to all of the source-level
-statement constructs. These are enumerated here, together with a list
-of the various macros that can be used to obtain information about
-them. There are a few macros that can be used with all statements:
-
-`STMT_LINENO'
- This macro returns the line number for the statement. If the
- statement spans multiple lines, this value will be the number of
- the first line on which the statement occurs. Although we mention
- `CASE_LABEL' below as if it were a statement, they do not allow
- the use of `STMT_LINENO'. There is no way to obtain the line
- number for a `CASE_LABEL'.
-
- Statements do not contain information about the file from which
- they came; that information is implicit in the `FUNCTION_DECL'
- from which the statements originate.
-
-`STMT_IS_FULL_EXPR_P'
- In C++, statements normally constitute "full expressions";
- temporaries created during a statement are destroyed when the
- statement is complete. However, G++ sometimes represents
- expressions by statements; these statements will not have
- `STMT_IS_FULL_EXPR_P' set. Temporaries created during such
- statements should be destroyed when the innermost enclosing
- statement with `STMT_IS_FULL_EXPR_P' set is exited.
-
-
- Here is the list of the various statement nodes, and the macros used
-to access them. This documentation describes the use of these nodes in
-non-template functions (including instantiations of template functions).
-In template functions, the same nodes are used, but sometimes in
-slightly different ways.
-
- Many of the statements have substatements. For example, a `while'
-loop will have a body, which is itself a statement. If the substatement
-is `NULL_TREE', it is considered equivalent to a statement consisting
-of a single `;', i.e., an expression statement in which the expression
-has been omitted. A substatement may in fact be a list of statements,
-connected via their `TREE_CHAIN's. So, you should always process the
-statement tree by looping over substatements, like this:
- void process_stmt (stmt)
- tree stmt;
- {
- while (stmt)
- {
- switch (TREE_CODE (stmt))
- {
- case IF_STMT:
- process_stmt (THEN_CLAUSE (stmt));
- /* More processing here. */
- break;
-
- ...
- }
-
- stmt = TREE_CHAIN (stmt);
- }
- }
- In other words, while the `then' clause of an `if' statement in C++
-can be only one statement (although that one statement may be a
-compound statement), the intermediate representation will sometimes use
-several statements chained together.
-
-`ASM_STMT'
- Used to represent an inline assembly statement. For an inline
- assembly statement like:
- asm ("mov x, y");
- The `ASM_STRING' macro will return a `STRING_CST' node for `"mov
- x, y"'. If the original statement made use of the
- extended-assembly syntax, then `ASM_OUTPUTS', `ASM_INPUTS', and
- `ASM_CLOBBERS' will be the outputs, inputs, and clobbers for the
- statement, represented as `STRING_CST' nodes. The
- extended-assembly syntax looks like:
- asm ("fsinx %1,%0" : "=f" (result) : "f" (angle));
- The first string is the `ASM_STRING', containing the instruction
- template. The next two strings are the output and inputs,
- respectively; this statement has no clobbers. As this example
- indicates, "plain" assembly statements are merely a special case
- of extended assembly statements; they have no cv-qualifiers,
- outputs, inputs, or clobbers. All of the strings will be
- `NUL'-terminated, and will contain no embedded `NUL'-characters.
-
- If the assembly statement is declared `volatile', or if the
- statement was not an extended assembly statement, and is therefore
- implicitly volatile, then the predicate `ASM_VOLATILE_P' will hold
- of the `ASM_STMT'.
-
-`BREAK_STMT'
- Used to represent a `break' statement. There are no additional
- fields.
-
-`CASE_LABEL'
- Use to represent a `case' label, range of `case' labels, or a
- `default' label. If `CASE_LOW' is `NULL_TREE', then this is a
- `default' label. Otherwise, if `CASE_HIGH' is `NULL_TREE', then
- this is an ordinary `case' label. In this case, `CASE_LOW' is an
- expression giving the value of the label. Both `CASE_LOW' and
- `CASE_HIGH' are `INTEGER_CST' nodes. These values will have the
- same type as the condition expression in the switch statement.
-
- Otherwise, if both `CASE_LOW' and `CASE_HIGH' are defined, the
- statement is a range of case labels. Such statements originate
- with the extension that allows users to write things of the form:
- case 2 ... 5:
- The first value will be `CASE_LOW', while the second will be
- `CASE_HIGH'.
-
-`CLEANUP_STMT'
- Used to represent an action that should take place upon exit from
- the enclosing scope. Typically, these actions are calls to
- destructors for local objects, but back ends cannot rely on this
- fact. If these nodes are in fact representing such destructors,
- `CLEANUP_DECL' will be the `VAR_DECL' destroyed. Otherwise,
- `CLEANUP_DECL' will be `NULL_TREE'. In any case, the
- `CLEANUP_EXPR' is the expression to execute. The cleanups
- executed on exit from a scope should be run in the reverse order
- of the order in which the associated `CLEANUP_STMT's were
- encountered.
-
-`COMPOUND_STMT'
- Used to represent a brace-enclosed block. The first substatement
- is given by `COMPOUND_BODY'. Subsequent substatements are found by
- following the `TREE_CHAIN' link from one substatement to the next.
- The `COMPOUND_BODY' will be `NULL_TREE' if there are no
- substatements.
-
-`CONTINUE_STMT'
- Used to represent a `continue' statement. There are no additional
- fields.
-
-`CTOR_STMT'
- Used to mark the beginning (if `CTOR_BEGIN_P' holds) or end (if
- `CTOR_END_P' holds of the main body of a constructor. See also
- `SUBOBJECT' for more information on how to use these nodes.
-
-`DECL_STMT'
- Used to represent a local declaration. The `DECL_STMT_DECL' macro
- can be used to obtain the entity declared. This declaration may
- be a `LABEL_DECL', indicating that the label declared is a local
- label. (As an extension, GCC allows the declaration of labels
- with scope.) In C, this declaration may be a `FUNCTION_DECL',
- indicating the use of the GCC nested function extension. For more
- information, *note Functions::.
-
-`DO_STMT'
- Used to represent a `do' loop. The body of the loop is given by
- `DO_BODY' while the termination condition for the loop is given by
- `DO_COND'. The condition for a `do'-statement is always an
- expression.
-
-`EMPTY_CLASS_EXPR'
- Used to represent a temporary object of a class with no data whose
- address is never taken. (All such objects are interchangeable.)
- The `TREE_TYPE' represents the type of the object.
-
-`EXPR_STMT'
- Used to represent an expression statement. Use `EXPR_STMT_EXPR' to
- obtain the expression.
-
-`FILE_STMT'
- Used to record a change in filename within the body of a function.
- Use `FILE_STMT_FILENAME' to obtain the new filename.
-
-`FOR_STMT'
- Used to represent a `for' statement. The `FOR_INIT_STMT' is the
- initialization statement for the loop. The `FOR_COND' is the
- termination condition. The `FOR_EXPR' is the expression executed
- right before the `FOR_COND' on each loop iteration; often, this
- expression increments a counter. The body of the loop is given by
- `FOR_BODY'. Note that `FOR_INIT_STMT' and `FOR_BODY' return
- statements, while `FOR_COND' and `FOR_EXPR' return expressions.
-
-`GOTO_STMT'
- Used to represent a `goto' statement. The `GOTO_DESTINATION' will
- usually be a `LABEL_DECL'. However, if the "computed goto"
- extension has been used, the `GOTO_DESTINATION' will be an
- arbitrary expression indicating the destination. This expression
- will always have pointer type. Additionally the `GOTO_FAKE_P'
- flag is set whenever the goto statement does not come from source
- code, but it is generated implicitly by the compiler. This is
- used for branch prediction.
-
-`HANDLER'
- Used to represent a C++ `catch' block. The `HANDLER_TYPE' is the
- type of exception that will be caught by this handler; it is equal
- (by pointer equality) to `CATCH_ALL_TYPE' if this handler is for
- all types. `HANDLER_PARMS' is the `DECL_STMT' for the catch
- parameter, and `HANDLER_BODY' is the `COMPOUND_STMT' for the block
- itself.
-
-`IF_STMT'
- Used to represent an `if' statement. The `IF_COND' is the
- expression.
-
- If the condition is a `TREE_LIST', then the `TREE_PURPOSE' is a
- statement (usually a `DECL_STMT'). Each time the condition is
- evaluated, the statement should be executed. Then, the
- `TREE_VALUE' should be used as the conditional expression itself.
- This representation is used to handle C++ code like this:
-
- if (int i = 7) ...
-
- where there is a new local variable (or variables) declared within
- the condition.
-
- The `THEN_CLAUSE' represents the statement given by the `then'
- condition, while the `ELSE_CLAUSE' represents the statement given
- by the `else' condition.
-
-`LABEL_STMT'
- Used to represent a label. The `LABEL_DECL' declared by this
- statement can be obtained with the `LABEL_STMT_LABEL' macro. The
- `IDENTIFIER_NODE' giving the name of the label can be obtained from
- the `LABEL_DECL' with `DECL_NAME'.
-
-`RETURN_INIT'
- If the function uses the G++ "named return value" extension,
- meaning that the function has been defined like:
- S f(int) return s {...}
- then there will be a `RETURN_INIT'. There is never a named
- returned value for a constructor. The first argument to the
- `RETURN_INIT' is the name of the object returned; the second
- argument is the initializer for the object. The object is
- initialized when the `RETURN_INIT' is encountered. The object
- referred to is the actual object returned; this extension is a
- manual way of doing the "return-value optimization." Therefore,
- the object must actually be constructed in the place where the
- object will be returned.
-
-`RETURN_STMT'
- Used to represent a `return' statement. The `RETURN_EXPR' is the
- expression returned; it will be `NULL_TREE' if the statement was
- just
- return;
-
-`SCOPE_STMT'
- A scope-statement represents the beginning or end of a scope. If
- `SCOPE_BEGIN_P' holds, this statement represents the beginning of a
- scope; if `SCOPE_END_P' holds this statement represents the end of
- a scope. On exit from a scope, all cleanups from `CLEANUP_STMT's
- occurring in the scope must be run, in reverse order to the order
- in which they were encountered. If `SCOPE_NULLIFIED_P' or
- `SCOPE_NO_CLEANUPS_P' holds of the scope, back ends should behave
- as if the `SCOPE_STMT' were not present at all.
-
-`SUBOBJECT'
- In a constructor, these nodes are used to mark the point at which a
- subobject of `this' is fully constructed. If, after this point, an
- exception is thrown before a `CTOR_STMT' with `CTOR_END_P' set is
- encountered, the `SUBOBJECT_CLEANUP' must be executed. The
- cleanups must be executed in the reverse order in which they
- appear.
-
-`SWITCH_STMT'
- Used to represent a `switch' statement. The `SWITCH_COND' is the
- expression on which the switch is occurring. See the documentation
- for an `IF_STMT' for more information on the representation used
- for the condition. The `SWITCH_BODY' is the body of the switch
- statement. The `SWITCH_TYPE' is the original type of switch
- expression as given in the source, before any compiler conversions.
-
-`TRY_BLOCK'
- Used to represent a `try' block. The body of the try block is
- given by `TRY_STMTS'. Each of the catch blocks is a `HANDLER'
- node. The first handler is given by `TRY_HANDLERS'. Subsequent
- handlers are obtained by following the `TREE_CHAIN' link from one
- handler to the next. The body of the handler is given by
- `HANDLER_BODY'.
-
- If `CLEANUP_P' holds of the `TRY_BLOCK', then the `TRY_HANDLERS'
- will not be a `HANDLER' node. Instead, it will be an expression
- that should be executed if an exception is thrown in the try
- block. It must rethrow the exception after executing that code.
- And, if an exception is thrown while the expression is executing,
- `terminate' must be called.
-
-`USING_STMT'
- Used to represent a `using' directive. The namespace is given by
- `USING_STMT_NAMESPACE', which will be a NAMESPACE_DECL. This node
- is needed inside template functions, to implement using directives
- during instantiation.
-
-`WHILE_STMT'
- Used to represent a `while' loop. The `WHILE_COND' is the
- termination condition for the loop. See the documentation for an
- `IF_STMT' for more information on the representation used for the
- condition.
-
- The `WHILE_BODY' is the body of the loop.
-
+File: gccint.info, Node: GNU Free Documentation License, Next: Contributors, Prev: Copying, Up: Top
+
+GNU Free Documentation License
+******************************
+
+ Version 1.1, March 2000
+
+ Copyright (C) 2000 Free Software Foundation, Inc.
+ 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
+
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+ 0. PREAMBLE
+
+ The purpose of this License is to make a manual, textbook, or other
+ written document "free" in the sense of freedom: to assure everyone
+ the effective freedom to copy and redistribute it, with or without
+ modifying it, either commercially or noncommercially. Secondarily,
+ this License preserves for the author and publisher a way to get
+ credit for their work, while not being considered responsible for
+ modifications made by others.
+
+ This License is a kind of "copyleft", which means that derivative
+ works of the document must themselves be free in the same sense.
+ It complements the GNU General Public License, which is a copyleft
+ license designed for free software.
+
+ We have designed this License in order to use it for manuals for
+ free software, because free software needs free documentation: a
+ free program should come with manuals providing the same freedoms
+ that the software does. But this License is not limited to
+ software manuals; it can be used for any textual work, regardless
+ of subject matter or whether it is published as a printed book.
+ We recommend this License principally for works whose purpose is
+ instruction or reference.
+
+ 1. APPLICABILITY AND DEFINITIONS
+
+ This License applies to any manual or other work that contains a
+ notice placed by the copyright holder saying it can be distributed
+ under the terms of this License. The "Document", below, refers to
+ any such manual or work. Any member of the public is a licensee,
+ and is addressed as "you".
+
+ A "Modified Version" of the Document means any work containing the
+ Document or a portion of it, either copied verbatim, or with
+ modifications and/or translated into another language.
+
+ A "Secondary Section" is a named appendix or a front-matter
+ section of the Document that deals exclusively with the
+ relationship of the publishers or authors of the Document to the
+ Document's overall subject (or to related matters) and contains
+ nothing that could fall directly within that overall subject.
+ (For example, if the Document is in part a textbook of
+ mathematics, a Secondary Section may not explain any mathematics.)
+ The relationship could be a matter of historical connection with
+ the subject or with related matters, or of legal, commercial,
+ philosophical, ethical or political position regarding them.
+
+ The "Invariant Sections" are certain Secondary Sections whose
+ titles are designated, as being those of Invariant Sections, in
+ the notice that says that the Document is released under this
+ License.
+
+ The "Cover Texts" are certain short passages of text that are
+ listed, as Front-Cover Texts or Back-Cover Texts, in the notice
+ that says that the Document is released under this License.
+
+ A "Transparent" copy of the Document means a machine-readable copy,
+ represented in a format whose specification is available to the
+ general public, whose contents can be viewed and edited directly
+ and straightforwardly with generic text editors or (for images
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+ Examples of suitable formats for Transparent copies include plain
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+ processors for output purposes only.
+
+ The "Title Page" means, for a printed book, the title page itself,
+ plus such following pages as are needed to hold, legibly, the
+ material this License requires to appear in the title page. For
+ works in formats which do not have any title page as such, "Title
+ Page" means the text near the most prominent appearance of the
+ work's title, preceding the beginning of the body of the text.
+
+ 2. VERBATIM COPYING
+
+ You may copy and distribute the Document in any medium, either
+ commercially or noncommercially, provided that this License, the
+ copyright notices, and the license notice saying this License
+ applies to the Document are reproduced in all copies, and that you
+ add no other conditions whatsoever to those of this License. You
+ may not use technical measures to obstruct or control the reading
+ or further copying of the copies you make or distribute. However,
+ you may accept compensation in exchange for copies. If you
+ distribute a large enough number of copies you must also follow
+ the conditions in section 3.
+
+ You may also lend copies, under the same conditions stated above,
+ and you may publicly display copies.
+
+ 3. COPYING IN QUANTITY
+
+ If you publish printed copies of the Document numbering more than
+ 100, and the Document's license notice requires Cover Texts, you
+ must enclose the copies in covers that carry, clearly and legibly,
+ all these Cover Texts: Front-Cover Texts on the front cover, and
+ Back-Cover Texts on the back cover. Both covers must also clearly
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+ front cover must present the full title with all words of the
+ title equally prominent and visible. You may add other material
+ on the covers in addition. Copying with changes limited to the
+ covers, as long as they preserve the title of the Document and
+ satisfy these conditions, can be treated as verbatim copying in
+ other respects.
+
+ If the required texts for either cover are too voluminous to fit
+ legibly, you should put the first ones listed (as many as fit
+ reasonably) on the actual cover, and continue the rest onto
+ adjacent pages.
+
+ If you publish or distribute Opaque copies of the Document
+ numbering more than 100, you must either include a
+ machine-readable Transparent copy along with each Opaque copy, or
+ state in or with each Opaque copy a publicly-accessible
+ computer-network location containing a complete Transparent copy
+ of the Document, free of added material, which the general
+ network-using public has access to download anonymously at no
+ charge using public-standard network protocols. If you use the
+ latter option, you must take reasonably prudent steps, when you
+ begin distribution of Opaque copies in quantity, to ensure that
+ this Transparent copy will remain thus accessible at the stated
+ location until at least one year after the last time you
+ distribute an Opaque copy (directly or through your agents or
+ retailers) of that edition to the public.
+
+ It is requested, but not required, that you contact the authors of
+ the Document well before redistributing any large number of
+ copies, to give them a chance to provide you with an updated
+ version of the Document.
+
+ 4. MODIFICATIONS
+
+ You may copy and distribute a Modified Version of the Document
+ under the conditions of sections 2 and 3 above, provided that you
+ release the Modified Version under precisely this License, with
+ the Modified Version filling the role of the Document, thus
+ licensing distribution and modification of the Modified Version to
+ whoever possesses a copy of it. In addition, you must do these
+ things in the Modified Version:
+
+ A. Use in the Title Page (and on the covers, if any) a title
+ distinct from that of the Document, and from those of
+ previous versions (which should, if there were any, be listed
+ in the History section of the Document). You may use the
+ same title as a previous version if the original publisher of
+ that version gives permission.
+
+ B. List on the Title Page, as authors, one or more persons or
+ entities responsible for authorship of the modifications in
+ the Modified Version, together with at least five of the
+ principal authors of the Document (all of its principal
+ authors, if it has less than five).
+
+ C. State on the Title page the name of the publisher of the
+ Modified Version, as the publisher.
+
+ D. Preserve all the copyright notices of the Document.
+
+ E. Add an appropriate copyright notice for your modifications
+ adjacent to the other copyright notices.
+
+ F. Include, immediately after the copyright notices, a license
+ notice giving the public permission to use the Modified
+ Version under the terms of this License, in the form shown in
+ the Addendum below.
+
+ G. Preserve in that license notice the full lists of Invariant
+ Sections and required Cover Texts given in the Document's
+ license notice.
+
+ H. Include an unaltered copy of this License.
+
+ I. Preserve the section entitled "History", and its title, and
+ add to it an item stating at least the title, year, new
+ authors, and publisher of the Modified Version as given on
+ the Title Page. If there is no section entitled "History" in
+ the Document, create one stating the title, year, authors,
+ and publisher of the Document as given on its Title Page,
+ then add an item describing the Modified Version as stated in
+ the previous sentence.
+
+ J. Preserve the network location, if any, given in the Document
+ for public access to a Transparent copy of the Document, and
+ likewise the network locations given in the Document for
+ previous versions it was based on. These may be placed in
+ the "History" section. You may omit a network location for a
+ work that was published at least four years before the
+ Document itself, or if the original publisher of the version
+ it refers to gives permission.
+
+ K. In any section entitled "Acknowledgments" or "Dedications",
+ preserve the section's title, and preserve in the section all
+ the substance and tone of each of the contributor
+ acknowledgments and/or dedications given therein.
+
+ L. Preserve all the Invariant Sections of the Document,
+ unaltered in their text and in their titles. Section numbers
+ or the equivalent are not considered part of the section
+ titles.
+
+ M. Delete any section entitled "Endorsements". Such a section
+ may not be included in the Modified Version.
+
+ N. Do not retitle any existing section as "Endorsements" or to
+ conflict in title with any Invariant Section.
+
+ If the Modified Version includes new front-matter sections or
+ appendices that qualify as Secondary Sections and contain no
+ material copied from the Document, you may at your option
+ designate some or all of these sections as invariant. To do this,
+ add their titles to the list of Invariant Sections in the Modified
+ Version's license notice. These titles must be distinct from any
+ other section titles.
+
+ You may add a section entitled "Endorsements", provided it contains
+ nothing but endorsements of your Modified Version by various
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+ has been approved by an organization as the authoritative
+ definition of a standard.
+
+ You may add a passage of up to five words as a Front-Cover Text,
+ and a passage of up to 25 words as a Back-Cover Text, to the end
+ of the list of Cover Texts in the Modified Version. Only one
+ passage of Front-Cover Text and one of Back-Cover Text may be
+ added by (or through arrangements made by) any one entity. If the
+ Document already includes a cover text for the same cover,
+ previously added by you or by arrangement made by the same entity
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+ replace the old one, on explicit permission from the previous
+ publisher that added the old one.
+
+ The author(s) and publisher(s) of the Document do not by this
+ License give permission to use their names for publicity for or to
+ assert or imply endorsement of any Modified Version.
+
+ 5. COMBINING DOCUMENTS
+
+ You may combine the Document with other documents released under
+ this License, under the terms defined in section 4 above for
+ modified versions, provided that you include in the combination
+ all of the Invariant Sections of all of the original documents,
+ unmodified, and list them all as Invariant Sections of your
+ combined work in its license notice.
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+ The combined work need only contain one copy of this License, and
+ multiple identical Invariant Sections may be replaced with a single
+ copy. If there are multiple Invariant Sections with the same name
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+ by adding at the end of it, in parentheses, the name of the
+ original author or publisher of that section if known, or else a
+ unique number. Make the same adjustment to the section titles in
+ the list of Invariant Sections in the license notice of the
+ combined work.
+
+ In the combination, you must combine any sections entitled
+ "History" in the various original documents, forming one section
+ entitled "History"; likewise combine any sections entitled
+ "Acknowledgments", and any sections entitled "Dedications". You
+ must delete all sections entitled "Endorsements."
+
+ 6. COLLECTIONS OF DOCUMENTS
+
+ You may make a collection consisting of the Document and other
+ documents released under this License, and replace the individual
+ copies of this License in the various documents with a single copy
+ that is included in the collection, provided that you follow the
+ rules of this License for verbatim copying of each of the
+ documents in all other respects.
+
+ You may extract a single document from such a collection, and
+ distribute it individually under this License, provided you insert
+ a copy of this License into the extracted document, and follow
+ this License in all other respects regarding verbatim copying of
+ that document.
+
+ 7. AGGREGATION WITH INDEPENDENT WORKS
+
+ A compilation of the Document or its derivatives with other
+ separate and independent documents or works, in or on a volume of
+ a storage or distribution medium, does not as a whole count as a
+ Modified Version of the Document, provided no compilation
+ copyright is claimed for the compilation. Such a compilation is
+ called an "aggregate", and this License does not apply to the
+ other self-contained works thus compiled with the Document, on
+ account of their being thus compiled, if they are not themselves
+ derivative works of the Document.
+
+ If the Cover Text requirement of section 3 is applicable to these
+ copies of the Document, then if the Document is less than one
+ quarter of the entire aggregate, the Document's Cover Texts may be
+ placed on covers that surround only the Document within the
+ aggregate. Otherwise they must appear on covers around the whole
+ aggregate.
+
+ 8. TRANSLATION
+
+ Translation is considered a kind of modification, so you may
+ distribute translations of the Document under the terms of section
+ 4. Replacing Invariant Sections with translations requires special
+ permission from their copyright holders, but you may include
+ translations of some or all Invariant Sections in addition to the
+ original versions of these Invariant Sections. You may include a
+ translation of this License provided that you also include the
+ original English version of this License. In case of a
+ disagreement between the translation and the original English
+ version of this License, the original English version will prevail.
+
+ 9. TERMINATION
+
+ You may not copy, modify, sublicense, or distribute the Document
+ except as expressly provided for under this License. Any other
+ attempt to copy, modify, sublicense or distribute the Document is
+ void, and will automatically terminate your rights under this
+ License. However, parties who have received copies, or rights,
+ from you under this License will not have their licenses
+ terminated so long as such parties remain in full compliance.
+
+ 10. FUTURE REVISIONS OF THIS LICENSE
+
+ The Free Software Foundation may publish new, revised versions of
+ the GNU Free Documentation License from time to time. Such new
+ versions will be similar in spirit to the present version, but may
+ differ in detail to address new problems or concerns. See
+ `http://www.gnu.org/copyleft/'.
+
+ Each version of the License is given a distinguishing version
+ number. If the Document specifies that a particular numbered
+ version of this License "or any later version" applies to it, you
+ have the option of following the terms and conditions either of
+ that specified version or of any later version that has been
+ published (not as a draft) by the Free Software Foundation. If
+ the Document does not specify a version number of this License,
+ you may choose any version ever published (not as a draft) by the
+ Free Software Foundation.
+
+ADDENDUM: How to use this License for your documents
+====================================================
+
+To use this License in a document you have written, include a copy of
+the License in the document and put the following copyright and license
+notices just after the title page:
+
+ Copyright (C) YEAR YOUR NAME.
+ Permission is granted to copy, distribute and/or modify this document
+ under the terms of the GNU Free Documentation License, Version 1.1
+ or any later version published by the Free Software Foundation;
+ with the Invariant Sections being LIST THEIR TITLES, with the
+ Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST.
+ A copy of the license is included in the section entitled ``GNU
+ Free Documentation License''.
+
+ If you have no Invariant Sections, write "with no Invariant Sections"
+instead of saying which ones are invariant. If you have no Front-Cover
+Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being
+LIST"; likewise for Back-Cover Texts.
+
+ If your document contains nontrivial examples of program code, we
+recommend releasing these examples in parallel under your choice of
+free software license, such as the GNU General Public License, to
+permit their use in free software.
\1f
-File: gccint.info, Node: Attributes, Next: Expression trees, Prev: Declarations, Up: Trees
+File: gccint.info, Node: Contributors, Next: Option Index, Prev: GNU Free Documentation License, Up: Top
-Attributes in trees
-===================
+Contributors to GCC
+*******************
- Attributes, as specified using the `__attribute__' keyword, are
-represented internally as a `TREE_LIST'. The `TREE_PURPOSE' is the
-name of the attribute, as an `IDENTIFIER_NODE'. The `TREE_VALUE' is a
-`TREE_LIST' of the arguments of the attribute, if any, or `NULL_TREE'
-if there are no arguments; the arguments are stored as the `TREE_VALUE'
-of successive entries in the list, and may be identifiers or
-expressions. The `TREE_CHAIN' of the attribute is the next attribute
-in a list of attributes applying to the same declaration or type, or
-`NULL_TREE' if there are no further attributes in the list.
+The GCC project would like to thank its many contributors. Without
+them the project would not have been nearly as successful as it has
+been. Any omissions in this list are accidental. Feel free to contact
+<law@redhat.com> if you have been left out or some of your
+contributions are not listed. Please keep this list in alphabetical
+order.
- Attributes may be attached to declarations and to types; these
-attributes may be accessed with the following macros. All attributes
-are stored in this way, and many also cause other changes to the
-declaration or type or to other internal compiler data structures.
+ * Analog Devices helped implement the support for complex data types
+ and iterators.
- - Tree Macro: tree DECL_ATTRIBUTES (tree DECL)
- This macro returns the attributes on the declaration DECL.
+ * John David Anglin for threading-related fixes and improvements to
+ libstdc++-v3, and the HP-UX port.
- - Tree Macro: tree TYPE_ATTRIBUTES (tree TYPE)
- This macro returns the attributes on the type TYPE.
+ * James van Artsdalen wrote the code that makes efficient use of the
+ Intel 80387 register stack.
-\1f
-File: gccint.info, Node: Expression trees, Prev: Attributes, Up: Trees
-
-Expressions
-===========
-
- The internal representation for expressions is for the most part
-quite straightforward. However, there are a few facts that one must
-bear in mind. In particular, the expression "tree" is actually a
-directed acyclic graph. (For example there may be many references to
-the integer constant zero throughout the source program; many of these
-will be represented by the same expression node.) You should not rely
-on certain kinds of node being shared, nor should rely on certain kinds
-of nodes being unshared.
-
- The following macros can be used with all expression nodes:
-
-`TREE_TYPE'
- Returns the type of the expression. This value may not be
- precisely the same type that would be given the expression in the
- original program.
-
- In what follows, some nodes that one might expect to always have type
-`bool' are documented to have either integral or boolean type. At some
-point in the future, the C front end may also make use of this same
-intermediate representation, and at this point these nodes will
-certainly have integral type. The previous sentence is not meant to
-imply that the C++ front end does not or will not give these nodes
-integral type.
-
- Below, we list the various kinds of expression nodes. Except where
-noted otherwise, the operands to an expression are accessed using the
-`TREE_OPERAND' macro. For example, to access the first operand to a
-binary plus expression `expr', use:
-
- TREE_OPERAND (expr, 0)
-
-As this example indicates, the operands are zero-indexed.
-
- The table below begins with constants, moves on to unary expressions,
-then proceeds to binary expressions, and concludes with various other
-kinds of expressions:
-
-`INTEGER_CST'
- These nodes represent integer constants. Note that the type of
- these constants is obtained with `TREE_TYPE'; they are not always
- of type `int'. In particular, `char' constants are represented
- with `INTEGER_CST' nodes. The value of the integer constant `e' is
- given by
- ((TREE_INT_CST_HIGH (e) << HOST_BITS_PER_WIDE_INT)
- + TREE_INST_CST_LOW (e))
-
- HOST_BITS_PER_WIDE_INT is at least thirty-two on all platforms.
- Both `TREE_INT_CST_HIGH' and `TREE_INT_CST_LOW' return a
- `HOST_WIDE_INT'. The value of an `INTEGER_CST' is interpreted as
- a signed or unsigned quantity depending on the type of the
- constant. In general, the expression given above will overflow,
- so it should not be used to calculate the value of the constant.
-
- The variable `integer_zero_node' is an integer constant with value
- zero. Similarly, `integer_one_node' is an integer constant with
- value one. The `size_zero_node' and `size_one_node' variables are
- analogous, but have type `size_t' rather than `int'.
-
- The function `tree_int_cst_lt' is a predicate which holds if its
- first argument is less than its second. Both constants are
- assumed to have the same signedness (i.e., either both should be
- signed or both should be unsigned.) The full width of the
- constant is used when doing the comparison; the usual rules about
- promotions and conversions are ignored. Similarly,
- `tree_int_cst_equal' holds if the two constants are equal. The
- `tree_int_cst_sgn' function returns the sign of a constant. The
- value is `1', `0', or `-1' according on whether the constant is
- greater than, equal to, or less than zero. Again, the signedness
- of the constant's type is taken into account; an unsigned constant
- is never less than zero, no matter what its bit-pattern.
-
-`REAL_CST'
- FIXME: Talk about how to obtain representations of this constant,
- do comparisons, and so forth.
-
-`COMPLEX_CST'
- These nodes are used to represent complex number constants, that
- is a `__complex__' whose parts are constant nodes. The
- `TREE_REALPART' and `TREE_IMAGPART' return the real and the
- imaginary parts respectively.
-
-`VECTOR_CST'
- These nodes are used to represent vector constants, whose parts are
- constant nodes. Each individual constant node is either an
- integer or a double constant node. The first operand is a
- `TREE_LIST' of the constant nodes and is accessed through
- `TREE_VECTOR_CST_ELTS'.
-
-`STRING_CST'
- These nodes represent string-constants. The `TREE_STRING_LENGTH'
- returns the length of the string, as an `int'. The
- `TREE_STRING_POINTER' is a `char*' containing the string itself.
- The string may not be `NUL'-terminated, and it may contain
- embedded `NUL' characters. Therefore, the `TREE_STRING_LENGTH'
- includes the trailing `NUL' if it is present.
-
- For wide string constants, the `TREE_STRING_LENGTH' is the number
- of bytes in the string, and the `TREE_STRING_POINTER' points to an
- array of the bytes of the string, as represented on the target
- system (that is, as integers in the target endianness). Wide and
- non-wide string constants are distinguished only by the `TREE_TYPE'
- of the `STRING_CST'.
-
- FIXME: The formats of string constants are not well-defined when
- the target system bytes are not the same width as host system
- bytes.
-
-`PTRMEM_CST'
- These nodes are used to represent pointer-to-member constants. The
- `PTRMEM_CST_CLASS' is the class type (either a `RECORD_TYPE' or
- `UNION_TYPE' within which the pointer points), and the
- `PTRMEM_CST_MEMBER' is the declaration for the pointed to object.
- Note that the `DECL_CONTEXT' for the `PTRMEM_CST_MEMBER' is in
- general different from the `PTRMEM_CST_CLASS'. For example, given:
- struct B { int i; };
- struct D : public B {};
- int D::*dp = &D::i;
-
- The `PTRMEM_CST_CLASS' for `&D::i' is `D', even though the
- `DECL_CONTEXT' for the `PTRMEM_CST_MEMBER' is `B', since `B::i' is
- a member of `B', not `D'.
-
-`VAR_DECL'
- These nodes represent variables, including static data members.
- For more information, *note Declarations::.
-
-`NEGATE_EXPR'
- These nodes represent unary negation of the single operand, for
- both integer and floating-point types. The type of negation can be
- determined by looking at the type of the expression.
-
-`BIT_NOT_EXPR'
- These nodes represent bitwise complement, and will always have
- integral type. The only operand is the value to be complemented.
-
-`TRUTH_NOT_EXPR'
- These nodes represent logical negation, and will always have
- integral (or boolean) type. The operand is the value being
- negated.
-
-`PREDECREMENT_EXPR'
-`PREINCREMENT_EXPR'
-`POSTDECREMENT_EXPR'
-`POSTINCREMENT_EXPR'
- These nodes represent increment and decrement expressions. The
- value of the single operand is computed, and the operand
- incremented or decremented. In the case of `PREDECREMENT_EXPR' and
- `PREINCREMENT_EXPR', the value of the expression is the value
- resulting after the increment or decrement; in the case of
- `POSTDECREMENT_EXPR' and `POSTINCREMENT_EXPR' is the value before
- the increment or decrement occurs. The type of the operand, like
- that of the result, will be either integral, boolean, or
- floating-point.
-
-`ADDR_EXPR'
- These nodes are used to represent the address of an object. (These
- expressions will always have pointer or reference type.) The
- operand may be another expression, or it may be a declaration.
-
- As an extension, GCC allows users to take the address of a label.
- In this case, the operand of the `ADDR_EXPR' will be a
- `LABEL_DECL'. The type of such an expression is `void*'.
-
- If the object addressed is not an lvalue, a temporary is created,
- and the address of the temporary is used.
-
-`INDIRECT_REF'
- These nodes are used to represent the object pointed to by a
- pointer. The operand is the pointer being dereferenced; it will
- always have pointer or reference type.
-
-`FIX_TRUNC_EXPR'
- These nodes represent conversion of a floating-point value to an
- integer. The single operand will have a floating-point type,
- while the the complete expression will have an integral (or
- boolean) type. The operand is rounded towards zero.
-
-`FLOAT_EXPR'
- These nodes represent conversion of an integral (or boolean) value
- to a floating-point value. The single operand will have integral
- type, while the complete expression will have a floating-point
- type.
-
- FIXME: How is the operand supposed to be rounded? Is this
- dependent on `-mieee'?
-
-`COMPLEX_EXPR'
- These nodes are used to represent complex numbers constructed from
- two expressions of the same (integer or real) type. The first
- operand is the real part and the second operand is the imaginary
- part.
-
-`CONJ_EXPR'
- These nodes represent the conjugate of their operand.
-
-`REALPART_EXPR'
-
-`IMAGPART_EXPR'
- These nodes represent respectively the real and the imaginary parts
- of complex numbers (their sole argument).
-
-`NON_LVALUE_EXPR'
- These nodes indicate that their one and only operand is not an
- lvalue. A back end can treat these identically to the single
- operand.
-
-`NOP_EXPR'
- These nodes are used to represent conversions that do not require
- any code-generation. For example, conversion of a `char*' to an
- `int*' does not require any code be generated; such a conversion is
- represented by a `NOP_EXPR'. The single operand is the expression
- to be converted. The conversion from a pointer to a reference is
- also represented with a `NOP_EXPR'.
-
-`CONVERT_EXPR'
- These nodes are similar to `NOP_EXPR's, but are used in those
- situations where code may need to be generated. For example, if an
- `int*' is converted to an `int' code may need to be generated on
- some platforms. These nodes are never used for C++-specific
- conversions, like conversions between pointers to different
- classes in an inheritance hierarchy. Any adjustments that need to
- be made in such cases are always indicated explicitly. Similarly,
- a user-defined conversion is never represented by a
- `CONVERT_EXPR'; instead, the function calls are made explicit.
-
-`THROW_EXPR'
- These nodes represent `throw' expressions. The single operand is
- an expression for the code that should be executed to throw the
- exception. However, there is one implicit action not represented
- in that expression; namely the call to `__throw'. This function
- takes no arguments. If `setjmp'/`longjmp' exceptions are used, the
- function `__sjthrow' is called instead. The normal GCC back end
- uses the function `emit_throw' to generate this code; you can
- examine this function to see what needs to be done.
-
-`LSHIFT_EXPR'
-`RSHIFT_EXPR'
- These nodes represent left and right shifts, respectively. The
- first operand is the value to shift; it will always be of integral
- type. The second operand is an expression for the number of bits
- by which to shift. Right shift should be treated as arithmetic,
- i.e., the high-order bits should be zero-filled when the
- expression has unsigned type and filled with the sign bit when the
- expression has signed type. Note that the result is undefined if
- the second operand is larger than the first operand's type size.
-
-`BIT_IOR_EXPR'
-`BIT_XOR_EXPR'
-`BIT_AND_EXPR'
- These nodes represent bitwise inclusive or, bitwise exclusive or,
- and bitwise and, respectively. Both operands will always have
- integral type.
-
-`TRUTH_ANDIF_EXPR'
-`TRUTH_ORIF_EXPR'
- These nodes represent logical and and logical or, respectively.
- These operators are not strict; i.e., the second operand is
- evaluated only if the value of the expression is not determined by
- evaluation of the first operand. The type of the operands, and
- the result type, is always of boolean or integral type.
-
-`TRUTH_AND_EXPR'
-`TRUTH_OR_EXPR'
-`TRUTH_XOR_EXPR'
- These nodes represent logical and, logical or, and logical
- exclusive or. They are strict; both arguments are always
- evaluated. There are no corresponding operators in C or C++, but
- the front end will sometimes generate these expressions anyhow, if
- it can tell that strictness does not matter.
-
-`PLUS_EXPR'
-`MINUS_EXPR'
-`MULT_EXPR'
-`TRUNC_DIV_EXPR'
-`TRUNC_MOD_EXPR'
-`RDIV_EXPR'
- These nodes represent various binary arithmetic operations.
- Respectively, these operations are addition, subtraction (of the
- second operand from the first), multiplication, integer division,
- integer remainder, and floating-point division. The operands to
- the first three of these may have either integral or floating
- type, but there will never be case in which one operand is of
- floating type and the other is of integral type.
-
- The result of a `TRUNC_DIV_EXPR' is always rounded towards zero.
- The `TRUNC_MOD_EXPR' of two operands `a' and `b' is always `a -
- a/b' where the division is as if computed by a `TRUNC_DIV_EXPR'.
-
-`ARRAY_REF'
- These nodes represent array accesses. The first operand is the
- array; the second is the index. To calculate the address of the
- memory accessed, you must scale the index by the size of the type
- of the array elements. The type of these expressions must be the
- type of a component of the array.
-
-`ARRAY_RANGE_REF'
- These nodes represent access to a range (or "slice") of an array.
- The operands are the same as that for `ARRAY_REF' and have the same
- meanings. The type of these expressions must be an array whose
- component type is the same as that of the first operand. The
- range of that array type determines the amount of data these
- expressions access.
-
-`EXACT_DIV_EXPR'
- Document.
-
-`LT_EXPR'
-`LE_EXPR'
-`GT_EXPR'
-`GE_EXPR'
-`EQ_EXPR'
-`NE_EXPR'
- These nodes represent the less than, less than or equal to, greater
- than, greater than or equal to, equal, and not equal comparison
- operators. The first and second operand with either be both of
- integral type or both of floating type. The result type of these
- expressions will always be of integral or boolean type.
-
-`MODIFY_EXPR'
- These nodes represent assignment. The left-hand side is the first
- operand; the right-hand side is the second operand. The left-hand
- side will be a `VAR_DECL', `INDIRECT_REF', `COMPONENT_REF', or
- other lvalue.
-
- These nodes are used to represent not only assignment with `=' but
- also compound assignments (like `+='), by reduction to `='
- assignment. In other words, the representation for `i += 3' looks
- just like that for `i = i + 3'.
-
-`INIT_EXPR'
- These nodes are just like `MODIFY_EXPR', but are used only when a
- variable is initialized, rather than assigned to subsequently.
-
-`COMPONENT_REF'
- These nodes represent non-static data member accesses. The first
- operand is the object (rather than a pointer to it); the second
- operand is the `FIELD_DECL' for the data member.
-
-`COMPOUND_EXPR'
- These nodes represent comma-expressions. The first operand is an
- expression whose value is computed and thrown away prior to the
- evaluation of the second operand. The value of the entire
- expression is the value of the second operand.
-
-`COND_EXPR'
- These nodes represent `?:' expressions. The first operand is of
- boolean or integral type. If it evaluates to a nonzero value, the
- second operand should be evaluated, and returned as the value of
- the expression. Otherwise, the third operand is evaluated, and
- returned as the value of the expression. As a GNU extension, the
- middle operand of the `?:' operator may be omitted in the source,
- like this:
-
- x ? : 3
-
- which is equivalent to
-
- x ? x : 3
-
- assuming that `x' is an expression without side-effects. However,
- in the case that the first operation causes side effects, the
- side-effects occur only once. Consumers of the internal
- representation do not need to worry about this oddity; the second
- operand will be always be present in the internal representation.
-
-`CALL_EXPR'
- These nodes are used to represent calls to functions, including
- non-static member functions. The first operand is a pointer to the
- function to call; it is always an expression whose type is a
- `POINTER_TYPE'. The second argument is a `TREE_LIST'. The
- arguments to the call appear left-to-right in the list. The
- `TREE_VALUE' of each list node contains the expression
- corresponding to that argument. (The value of `TREE_PURPOSE' for
- these nodes is unspecified, and should be ignored.) For non-static
- member functions, there will be an operand corresponding to the
- `this' pointer. There will always be expressions corresponding to
- all of the arguments, even if the function is declared with default
- arguments and some arguments are not explicitly provided at the
- call sites.
-
-`STMT_EXPR'
- These nodes are used to represent GCC's statement-expression
- extension. The statement-expression extension allows code like
- this:
- int f() { return ({ int j; j = 3; j + 7; }); }
- In other words, an sequence of statements may occur where a single
- expression would normally appear. The `STMT_EXPR' node represents
- such an expression. The `STMT_EXPR_STMT' gives the statement
- contained in the expression; this is always a `COMPOUND_STMT'. The
- value of the expression is the value of the last sub-statement in
- the `COMPOUND_STMT'. More precisely, the value is the value
- computed by the last `EXPR_STMT' in the outermost scope of the
- `COMPOUND_STMT'. For example, in:
- ({ 3; })
- the value is `3' while in:
- ({ if (x) { 3; } })
- (represented by a nested `COMPOUND_STMT'), there is no value. If
- the `STMT_EXPR' does not yield a value, it's type will be `void'.
-
-`BIND_EXPR'
- These nodes represent local blocks. The first operand is a list of
- temporary variables, connected via their `TREE_CHAIN' field. These
- will never require cleanups. The scope of these variables is just
- the body of the `BIND_EXPR'. The body of the `BIND_EXPR' is the
- second operand.
-
-`LOOP_EXPR'
- These nodes represent "infinite" loops. The `LOOP_EXPR_BODY'
- represents the body of the loop. It should be executed forever,
- unless an `EXIT_EXPR' is encountered.
-
-`EXIT_EXPR'
- These nodes represent conditional exits from the nearest enclosing
- `LOOP_EXPR'. The single operand is the condition; if it is
- nonzero, then the loop should be exited. An `EXIT_EXPR' will only
- appear within a `LOOP_EXPR'.
-
-`CLEANUP_POINT_EXPR'
- These nodes represent full-expressions. The single operand is an
- expression to evaluate. Any destructor calls engendered by the
- creation of temporaries during the evaluation of that expression
- should be performed immediately after the expression is evaluated.
-
-`CONSTRUCTOR'
- These nodes represent the brace-enclosed initializers for a
- structure or array. The first operand is reserved for use by the
- back end. The second operand is a `TREE_LIST'. If the
- `TREE_TYPE' of the `CONSTRUCTOR' is a `RECORD_TYPE' or
- `UNION_TYPE', then the `TREE_PURPOSE' of each node in the
- `TREE_LIST' will be a `FIELD_DECL' and the `TREE_VALUE' of each
- node will be the expression used to initialize that field. You
- should not depend on the fields appearing in any particular order,
- nor should you assume that all fields will be represented.
- Unrepresented fields may be assigned any value.
-
- If the `TREE_TYPE' of the `CONSTRUCTOR' is an `ARRAY_TYPE', then
- the `TREE_PURPOSE' of each element in the `TREE_LIST' will be an
- `INTEGER_CST'. This constant indicates which element of the array
- (indexed from zero) is being assigned to; again, the `TREE_VALUE'
- is the corresponding initializer. If the `TREE_PURPOSE' is
- `NULL_TREE', then the initializer is for the next available array
- element.
-
- Conceptually, before any initialization is done, the entire area of
- storage is initialized to zero.
-
-`COMPOUND_LITERAL_EXPR'
- These nodes represent ISO C99 compound literals. The
- `COMPOUND_LITERAL_EXPR_DECL_STMT' is a `DECL_STMT' containing an
- anonymous `VAR_DECL' for the unnamed object represented by the
- compound literal; the `DECL_INITIAL' of that `VAR_DECL' is a
- `CONSTRUCTOR' representing the brace-enclosed list of initializers
- in the compound literal. That anonymous `VAR_DECL' can also be
- accessed directly by the `COMPOUND_LITERAL_EXPR_DECL' macro.
-
-`SAVE_EXPR'
- A `SAVE_EXPR' represents an expression (possibly involving
- side-effects) that is used more than once. The side-effects should
- occur only the first time the expression is evaluated. Subsequent
- uses should just reuse the computed value. The first operand to
- the `SAVE_EXPR' is the expression to evaluate. The side-effects
- should be executed where the `SAVE_EXPR' is first encountered in a
- depth-first preorder traversal of the expression tree.
-
-`TARGET_EXPR'
- A `TARGET_EXPR' represents a temporary object. The first operand
- is a `VAR_DECL' for the temporary variable. The second operand is
- the initializer for the temporary. The initializer is evaluated,
- and copied (bitwise) into the temporary.
-
- Often, a `TARGET_EXPR' occurs on the right-hand side of an
- assignment, or as the second operand to a comma-expression which is
- itself the right-hand side of an assignment, etc. In this case,
- we say that the `TARGET_EXPR' is "normal"; otherwise, we say it is
- "orphaned". For a normal `TARGET_EXPR' the temporary variable
- should be treated as an alias for the left-hand side of the
- assignment, rather than as a new temporary variable.
-
- The third operand to the `TARGET_EXPR', if present, is a
- cleanup-expression (i.e., destructor call) for the temporary. If
- this expression is orphaned, then this expression must be executed
- when the statement containing this expression is complete. These
- cleanups must always be executed in the order opposite to that in
- which they were encountered. Note that if a temporary is created
- on one branch of a conditional operator (i.e., in the second or
- third operand to a `COND_EXPR'), the cleanup must be run only if
- that branch is actually executed.
-
- See `STMT_IS_FULL_EXPR_P' for more information about running these
- cleanups.
-
-`AGGR_INIT_EXPR'
- An `AGGR_INIT_EXPR' represents the initialization as the return
- value of a function call, or as the result of a constructor. An
- `AGGR_INIT_EXPR' will only appear as the second operand of a
- `TARGET_EXPR'. The first operand to the `AGGR_INIT_EXPR' is the
- address of a function to call, just as in a `CALL_EXPR'. The
- second operand are the arguments to pass that function, as a
- `TREE_LIST', again in a manner similar to that of a `CALL_EXPR'.
- The value of the expression is that returned by the function.
-
- If `AGGR_INIT_VIA_CTOR_P' holds of the `AGGR_INIT_EXPR', then the
- initialization is via a constructor call. The address of the third
- operand of the `AGGR_INIT_EXPR', which is always a `VAR_DECL', is
- taken, and this value replaces the first argument in the argument
- list. In this case, the value of the expression is the `VAR_DECL'
- given by the third operand to the `AGGR_INIT_EXPR'; constructors do
- not return a value.
-
-`VTABLE_REF'
- A `VTABLE_REF' indicates that the interior expression computes a
- value that is a vtable entry. It is used with `-fvtable-gc' to
- track the reference through to front end to the middle end, at
- which point we transform this to a `REG_VTABLE_REF' note, which
- survives the balance of code generation.
-
- The first operand is the expression that computes the vtable
- reference. The second operand is the `VAR_DECL' of the vtable.
- The third operand is an `INTEGER_CST' of the byte offset into the
- vtable.
+ * Alasdair Baird for various bugfixes.
+ * Gerald Baumgartner added the signature extension to the C++ front
+ end.
-\1f
-File: gccint.info, Node: RTL, Next: Machine Desc, Prev: Trees, Up: Top
+ * Godmar Back for his Java improvements and encouragement.
+
+ * Scott Bambrough for help porting the Java compiler.
+
+ * Jon Beniston for his Win32 port of Java.
+
+ * Geoff Berry for his Java object serialization work and various
+ patches.
+
+ * Eric Blake for helping to make GCJ and libgcj conform to the
+ specifications.
+
+ * Hans-J. Boehm for his garbage collector, IA-64 libffi port, and
+ other Java work.
+
+ * Neil Booth for work on cpplib, lang hooks, debug hooks and other
+ miscellaneous clean-ups.
+
+ * Per Bothner for his direction via the steering committee and
+ various improvements to our infrastructure for supporting new
+ languages. Chill front end implementation. Initial
+ implementations of cpplib, fix-header, config.guess, libio, and
+ past C++ library (libg++) maintainer. Dreaming up, designing and
+ implementing much of GCJ.
+
+ * Devon Bowen helped port GCC to the Tahoe.
+
+ * Don Bowman for mips-vxworks contributions.
+
+ * Dave Brolley for work on cpplib and Chill.
+
+ * Robert Brown implemented the support for Encore 32000 systems.
+
+ * Christian Bruel for improvements to local store elimination.
+
+ * Herman A.J. ten Brugge for various fixes.
+
+ * Joerg Brunsmann for Java compiler hacking and help with the GCJ
+ FAQ.
+
+ * Joe Buck for his direction via the steering committee.
+
+ * Craig Burley for leadership of the Fortran effort.
+
+ * Stephan Buys for contributing Doxygen notes for libstdc++.
+
+ * Paolo Carlini for libstdc++ work: lots of efficiency improvements
+ to the string class, hard detective work on the frustrating
+ localization issues, and keeping up with the problem reports.
+
+ * John Carr for his alias work, SPARC hacking, infrastructure
+ improvements, previous contributions to the steering committee,
+ loop optimizations, etc.
+
+ * Steve Chamberlain for support for the Hitachi SH and H8 processors
+ and the PicoJava processor, and for GCJ config fixes.
+
+ * Glenn Chambers for help with the GCJ FAQ.
+
+ * John-Marc Chandonia for various libgcj patches.
+
+ * Scott Christley for his Objective-C contributions.
+
+ * Eric Christopher for his Java porting help and clean-ups.
+
+ * Branko Cibej for more warning contributions.
+
+ * The GNU Classpath project for all of their merged runtime code.
+
+ * Nick Clifton for arm, mcore, fr30, v850, m32r work, `--help', and
+ other random hacking.
+
+ * Michael Cook for libstdc++ cleanup patches to reduce warnings.
+
+ * Ralf Corsepius for SH testing and minor bugfixing.
+
+ * Stan Cox for care and feeding of the x86 port and lots of behind
+ the scenes hacking.
+
+ * Alex Crain provided changes for the 3b1.
+
+ * Ian Dall for major improvements to the NS32k port.
+
+ * Dario Dariol contributed the four varieties of sample programs
+ that print a copy of their source.
+
+ * Russell Davidson for fstream and stringstream fixes in libstdc++.
+
+ * Mo DeJong for GCJ and libgcj bug fixes.
+
+ * Gabriel Dos Reis for contributions to g++, contributions and
+ maintenance of GCC diagnostics infrastructure, libstdc++-v3,
+ including valarray<>, complex<>, maintaining the numerics library
+ (including that pesky <limits> :-) and keeping up-to-date anything
+ to do with numbers.
+
+ * Ulrich Drepper for his work on glibc, testing of GCC using glibc,
+ ISO C99 support, CFG dumping support, etc., plus support of the
+ C++ runtime libraries including for all kinds of C interface
+ issues, contributing and maintaining complex<>, sanity checking
+ and disbursement, configuration architecture, libio maintenance,
+ and early math work.
+
+ * Richard Earnshaw for his ongoing work with the ARM.
+
+ * David Edelsohn for his direction via the steering committee,
+ ongoing work with the RS6000/PowerPC port, help cleaning up Haifa
+ loop changes, and for doing the entire AIX port of libstdc++ with
+ his bare hands.
+
+ * Kevin Ediger for the floating point formatting of num_put::do_put
+ in libstdc++.
+
+ * Phil Edwards for libstdc++ work including configuration hackery,
+ documentation maintainer, chief breaker of the web pages, the
+ occasional iostream bugfix, and work on shared library symbol
+ versioning.
+
+ * Paul Eggert for random hacking all over GCC.
+
+ * Mark Elbrecht for various DJGPP improvements, and for libstdc++
+ configuration support for locales and fstream-related fixes.
+
+ * Vadim Egorov for libstdc++ fixes in strings, streambufs, and
+ iostreams.
+
+ * Ben Elliston for his work to move the Objective-C runtime into its
+ own subdirectory and for his work on autoconf.
+
+ * Marc Espie for OpenBSD support.
+
+ * Doug Evans for much of the global optimization framework, arc,
+ m32r, and SPARC work.
+
+ * Fred Fish for BeOS support and Ada fixes.
+
+ * Ivan Fontes Garcia for the Portugese translation of the GCJ FAQ.
+
+ * Peter Gerwinski for various bugfixes and the Pascal front end.
+
+ * Kaveh Ghazi for his direction via the steering committee and
+ amazing work to make `-W -Wall' useful.
+
+ * John Gilmore for a donation to the FSF earmarked improving GNU
+ Java.
+
+ * Judy Goldberg for c++ contributions.
+
+ * Torbjorn Granlund for various fixes and the c-torture testsuite,
+ multiply- and divide-by-constant optimization, improved long long
+ support, improved leaf function register allocation, and his
+ direction via the steering committee.
+
+ * Anthony Green for his `-Os' contributions and Java front end work.
+
+ * Stu Grossman for gdb hacking, allowing GCJ developers to debug our
+ code.
+
+ * Michael K. Gschwind contributed the port to the PDP-11.
+
+ * Ron Guilmette implemented the `protoize' and `unprotoize' tools,
+ the support for Dwarf symbolic debugging information, and much of
+ the support for System V Release 4. He has also worked heavily on
+ the Intel 386 and 860 support.
+
+ * Bruno Haible for improvements in the runtime overhead for EH, new
+ warnings and assorted bugfixes.
+
+ * Andrew Haley for his amazing Java compiler and library efforts.
+
+ * Chris Hanson assisted in making GCC work on HP-UX for the 9000
+ series 300.
+
+ * Michael Hayes for various thankless work he's done trying to get
+ the c30/c40 ports functional. Lots of loop and unroll
+ improvements and fixes.
+
+ * Kate Hedstrom for staking the g77 folks with an initial testsuite.
+
+ * Richard Henderson for his ongoing SPARC, alpha, and ia32 work, loop
+ opts, and generally fixing lots of old problems we've ignored for
+ years, flow rewrite and lots of further stuff, including reviewing
+ tons of patches.
+
+ * Nobuyuki Hikichi of Software Research Associates, Tokyo,
+ contributed the support for the Sony NEWS machine.
+
+ * Manfred Hollstein for his ongoing work to keep the m88k alive, lots
+ of testing an bugfixing, particularly of our configury code.
+
+ * Steve Holmgren for MachTen patches.
+
+ * Jan Hubicka for his x86 port improvements.
+
+ * Christian Iseli for various bugfixes.
+
+ * Kamil Iskra for general m68k hacking.
+
+ * Lee Iverson for random fixes and MIPS testing.
+
+ * Andreas Jaeger for various fixes to the MIPS port
+
+ * Jakub Jelinek for his SPARC work and sibling call optimizations as
+ well as lots of bug fixes and test cases, and for improving the
+ Java build system.
+
+ * Janis Johnson for ia64 testing and fixes and for her quality
+ improvement sidetracks.
+
+ * J. Kean Johnston for OpenServer support.
+
+ * Tim Josling for the sample language treelang based originally on
+ Richard Kenner's ""toy" language".
+
+ * Nicolai Josuttis for additional libstdc++ documentation.
+
+ * Klaus Kaempf for his ongoing work to make alpha-vms a viable
+ target.
+
+ * David Kashtan of SRI adapted GCC to VMS.
+
+ * Ryszard Kabatek for many, many libstdc++ bugfixes and
+ optimizations of strings, especially member functions, and for
+ auto_ptr fixes.
+
+ * Geoffrey Keating for his ongoing work to make the PPC work for
+ GNU/Linux and his automatic regression tester.
+
+ * Brendan Kehoe for his ongoing work with g++ and for a lot of early
+ work in just about every part of libstdc++.
+
+ * Oliver M. Kellogg of Deutsche Aerospace contributed the port to the
+ MIL-STD-1750A.
+
+ * Richard Kenner of the New York University Ultracomputer Research
+ Laboratory wrote the machine descriptions for the AMD 29000, the
+ DEC Alpha, the IBM RT PC, and the IBM RS/6000 as well as the
+ support for instruction attributes. He also made changes to
+ better support RISC processors including changes to common
+ subexpression elimination, strength reduction, function calling
+ sequence handling, and condition code support, in addition to
+ generalizing the code for frame pointer elimination and delay slot
+ scheduling. Richard Kenner was also the head maintainer of GCC
+ for several years.
+
+ * Mumit Khan for various contributions to the Cygwin and Mingw32
+ ports and maintaining binary releases for Windows hosts, and for
+ massive libstdc++ porting work to Cygwin/Mingw32.
+
+ * Robin Kirkham for cpu32 support.
+
+ * Mark Klein for PA improvements.
+
+ * Thomas Koenig for various bugfixes.
+
+ * Bruce Korb for the new and improved fixincludes code.
+
+ * Benjamin Kosnik for his g++ work and for leading the libstdc++-v3
+ effort.
+
+ * Charles LaBrec contributed the support for the Integrated Solutions
+ 68020 system.
+
+ * Jeff Law for his direction via the steering committee,
+ coordinating the entire egcs project and GCC 2.95, rolling out
+ snapshots and releases, handling merges from GCC2, reviewing tons
+ of patches that might have fallen through the cracks else, and
+ random but extensive hacking.
+
+ * Marc Lehmann for his direction via the steering committee and
+ helping with analysis and improvements of x86 performance.
+
+ * Ted Lemon wrote parts of the RTL reader and printer.
+
+ * Kriang Lerdsuwanakij for improvements to demangler and various c++
+ fixes.
+
+ * Warren Levy for tremendous work on libgcj (Java Runtime Library)
+ and random work on the Java front end.
+
+ * Alain Lichnewsky ported GCC to the MIPS CPU.
+
+ * Oskar Liljeblad for hacking on AWT and his many Java bug reports
+ and patches.
+
+ * Robert Lipe for OpenServer support, new testsuites, testing, etc.
+
+ * Weiwen Liu for testing and various bugfixes.
+
+ * Dave Love for his ongoing work with the Fortran front end and
+ runtime libraries.
+
+ * Martin von Lo"wis for internal consistency checking infrastructure,
+ various C++ improvements including namespace support, and tons of
+ assistance with libstdc++/compiler merges.
+
+ * H.J. Lu for his previous contributions to the steering committee,
+ many x86 bug reports, prototype patches, and keeping the GNU/Linux
+ ports working.
+
+ * Greg McGary for random fixes and (someday) bounded pointers.
+
+ * Andrew MacLeod for his ongoing work in building a real EH system,
+ various code generation improvements, work on the global
+ optimizer, etc.
+
+ * Vladimir Makarov for hacking some ugly i960 problems, PowerPC
+ hacking improvements to compile-time performance, overall
+ knowledge and direction in the area of instruction scheduling, and
+ design and implementation of the automaton based instruction
+ scheduler.
+
+ * Bob Manson for his behind the scenes work on dejagnu.
+
+ * Philip Martin for lots of libstdc++ string and vector iterator
+ fixes and improvements, and string clean up and testsuites.
+
+ * All of the Mauve project contributors, for Java test code.
+
+ * Bryce McKinlay for numerous GCJ and libgcj fixes and improvements.
+
+ * Adam Megacz for his work on the Win32 port of GCJ.
+
+ * Michael Meissner for LRS framework, ia32, m32r, v850, m88k, MIPS,
+ powerpc, haifa, ECOFF debug support, and other assorted hacking.
+
+ * Jason Merrill for his direction via the steering committee and
+ leading the g++ effort.
+
+ * David Miller for his direction via the steering committee, lots of
+ SPARC work, improvements in jump.c and interfacing with the Linux
+ kernel developers.
+
+ * Gary Miller ported GCC to Charles River Data Systems machines.
+
+ * Alfred Minarik for libstdc++ string and ios bugfixes, and turning
+ the entire libstdc++ testsuite namespace-compatible.
+
+ * Mark Mitchell for his direction via the steering committee,
+ mountains of C++ work, load/store hoisting out of loops, alias
+ analysis improvements, ISO C `restrict' support, and serving as
+ release manager for GCC 3.x.
+
+ * Alan Modra for various GNU/Linux bits and testing.
+
+ * Toon Moene for his direction via the steering committee, Fortran
+ maintenance, and his ongoing work to make us make Fortran run fast.
+
+ * Jason Molenda for major help in the care and feeding of all the
+ services on the gcc.gnu.org (formerly egcs.cygnus.com)
+ machine--mail, web services, ftp services, etc etc. Doing all
+ this work on scrap paper and the backs of envelopes would have
+ been... difficult.
+
+ * Catherine Moore for fixing various ugly problems we have sent her
+ way, including the haifa bug which was killing the Alpha & PowerPC
+ Linux kernels.
+
+ * Mike Moreton for his various Java patches.
+
+ * David Mosberger-Tang for various Alpha improvements.
+
+ * Stephen Moshier contributed the floating point emulator that
+ assists in cross-compilation and permits support for floating
+ point numbers wider than 64 bits and for ISO C99 support.
+
+ * Bill Moyer for his behind the scenes work on various issues.
+
+ * Philippe De Muyter for his work on the m68k port.
+
+ * Joseph S. Myers for his work on the PDP-11 port, format checking
+ and ISO C99 support, and continuous emphasis on (and contributions
+ to) documentation.
+
+ * Nathan Myers for his work on libstdc++-v3: architecture and
+ authorship through the first three snapshots, including
+ implementation of locale infrastructure, string, shadow C headers,
+ and the initial project documentation (DESIGN, CHECKLIST, and so
+ forth). Later, more work on MT-safe string and shadow headers.
+
+ * Felix Natter for documentation on porting libstdc++.
+
+ * NeXT, Inc. donated the front end that supports the Objective-C
+ language.
+
+ * Hans-Peter Nilsson for the CRIS and MMIX ports, improvements to
+ the search engine setup, various documentation fixes and other
+ small fixes.
+
+ * Geoff Noer for this work on getting cygwin native builds working.
+
+ * David O'Brien for the FreeBSD/alpha, FreeBSD/AMD x86-64,
+ FreeBSD/ARM, FreeBSD/PowerPC, and FreeBSD/SPARC64 ports and
+ related infrastructure improvements.
+
+ * Alexandre Oliva for various build infrastructure improvements,
+ scripts and amazing testing work, including keeping libtool issues
+ sane and happy.
+
+ * Melissa O'Neill for various NeXT fixes.
+
+ * Rainer Orth for random MIPS work, including improvements to our o32
+ ABI support, improvements to dejagnu's MIPS support, Java
+ configuration clean-ups and porting work, etc.
+
+ * Paul Petersen wrote the machine description for the Alliant FX/8.
+
+ * Alexandre Petit-Bianco for implementing much of the Java compiler
+ and continued Java maintainership.
+
+ * Matthias Pfaller for major improvements to the NS32k port.
+
+ * Gerald Pfeifer for his direction via the steering committee,
+ pointing out lots of problems we need to solve, maintenance of the
+ web pages, and taking care of documentation maintenance in general.
+
+ * Ovidiu Predescu for his work on the Objective-C front end and
+ runtime libraries.
+
+ * Ken Raeburn for various improvements to checker, MIPS ports and
+ various cleanups in the compiler.
+
+ * Rolf W. Rasmussen for hacking on AWT.
+
+ * David Reese of Sun Microsystems contributed to the Solaris on
+ PowerPC port.
+
+ * Joern Rennecke for maintaining the sh port, loop, regmove & reload
+ hacking.
+
+ * Loren J. Rittle for improvements to libstdc++-v3 including the
+ FreeBSD port, threading fixes, thread-related configury changes,
+ critical threading documentation, and solutions to really tricky
+ I/O problems.
+
+ * Craig Rodrigues for processing tons of bug reports.
+
+ * Gavin Romig-Koch for lots of behind the scenes MIPS work.
+
+ * Ken Rose for fixes to our delay slot filling code.
+
+ * Paul Rubin wrote most of the preprocessor.
+
+ * Chip Salzenberg for libstdc++ patches and improvements to locales,
+ traits, Makefiles, libio, libtool hackery, and "long long" support.
+
+ * Juha Sarlin for improvements to the H8 code generator.
-RTL Representation
-******************
+ * Greg Satz assisted in making GCC work on HP-UX for the 9000 series
+ 300.
- Most of the work of the compiler is done on an intermediate
-representation called register transfer language. In this language,
-the instructions to be output are described, pretty much one by one, in
-an algebraic form that describes what the instruction does.
+ * Bradley Schatz for his work on the GCJ FAQ.
- RTL is inspired by Lisp lists. It has both an internal form, made
-up of structures that point at other structures, and a textual form
-that is used in the machine description and in printed debugging dumps.
-The textual form uses nested parentheses to indicate the pointers in
-the internal form.
+ * Peter Schauer wrote the code to allow debugging to work on the
+ Alpha.
+ * William Schelter did most of the work on the Intel 80386 support.
+
+ * Bernd Schmidt for various code generation improvements and major
+ work in the reload pass as well a serving as release manager for
+ GCC 2.95.3.
+
+ * Peter Schmid for constant testing of libstdc++ - especially
+ application testing, going above and beyond what was requested for
+ the release criteria - and libstdc++ header file tweaks.
+
+ * Jason Schroeder for jcf-dump patches.
+
+ * Andreas Schwab for his work on the m68k port.
+
+ * Joel Sherrill for his direction via the steering committee, RTEMS
+ contributions and RTEMS testing.
+
+ * Nathan Sidwell for many C++ fixes/improvements.
+
+ * Jeffrey Siegal for helping RMS with the original design of GCC,
+ some code which handles the parse tree and RTL data structures,
+ constant folding and help with the original VAX & m68k ports.
+
+ * Kenny Simpson for prompting libstdc++ fixes due to defect reports
+ from the LWG (thereby keeping us in line with updates from the
+ ISO).
+
+ * Franz Sirl for his ongoing work with making the PPC port stable
+ for linux.
+
+ * Andrey Slepuhin for assorted AIX hacking.
+
+ * Christopher Smith did the port for Convex machines.
+
+ * Randy Smith finished the Sun FPA support.
+
+ * Scott Snyder for queue, iterator, istream, and string fixes and
+ libstdc++ testsuite entries.
+
+ * Brad Spencer for contributions to the GLIBCPP_FORCE_NEW technique.
+
+ * Richard Stallman, for writing the original gcc and launching the
+ GNU project.
+
+ * Jan Stein of the Chalmers Computer Society provided support for
+ Genix, as well as part of the 32000 machine description.
+
+ * Nigel Stephens for various mips16 related fixes/improvements.
+
+ * Jonathan Stone wrote the machine description for the Pyramid
+ computer.
+
+ * Graham Stott for various infrastructure improvements.
+
+ * John Stracke for his Java HTTP protocol fixes.
+
+ * Mike Stump for his Elxsi port, g++ contributions over the years
+ and more recently his vxworks contributions
+
+ * Jeff Sturm for Java porting help, bug fixes, and encouragement.
+
+ * Shigeya Suzuki for this fixes for the bsdi platforms.
+
+ * Ian Lance Taylor for his mips16 work, general configury hacking,
+ fixincludes, etc.
+
+ * Holger Teutsch provided the support for the Clipper CPU.
+
+ * Gary Thomas for his ongoing work to make the PPC work for
+ GNU/Linux.
+
+ * Philipp Thomas for random bugfixes throughout the compiler
+
+ * Jason Thorpe for thread support in libstdc++ on NetBSD.
+
+ * Kresten Krab Thorup wrote the run time support for the Objective-C
+ language and the fantastic Java bytecode interpreter.
+
+ * Michael Tiemann for random bugfixes, the first instruction
+ scheduler, initial C++ support, function integration, NS32k, SPARC
+ and M88k machine description work, delay slot scheduling.
+
+ * Andreas Tobler for his work porting libgcj to Darwin.
+
+ * Teemu Torma for thread safe exception handling support.
+
+ * Leonard Tower wrote parts of the parser, RTL generator, and RTL
+ definitions, and of the VAX machine description.
+
+ * Tom Tromey for internationalization support and for his many Java
+ contributions and libgcj maintainership.
+
+ * Lassi Tuura for improvements to config.guess to determine HP
+ processor types.
+
+ * Petter Urkedal for libstdc++ CXXFLAGS, math, and algorithms fixes.
+
+ * Brent Verner for work with the libstdc++ cshadow files and their
+ associated configure steps.
+
+ * Todd Vierling for contributions for NetBSD ports.
+
+ * Jonathan Wakely for contributing libstdc++ Doxygen notes and XHTML
+ guidance.
+
+ * Dean Wakerley for converting the install documentation from HTML
+ to texinfo in time for GCC 3.0.
+
+ * Krister Walfridsson for random bugfixes.
+
+ * Stephen M. Webb for time and effort on making libstdc++ shadow
+ files work with the tricky Solaris 8+ headers, and for pushing the
+ build-time header tree.
+
+ * John Wehle for various improvements for the x86 code generator,
+ related infrastructure improvements to help x86 code generation,
+ value range propagation and other work, WE32k port.
+
+ * Zack Weinberg for major work on cpplib and various other bugfixes.
+
+ * Matt Welsh for help with Linux Threads support in GCJ.
+
+ * Urban Widmark for help fixing java.io.
+
+ * Mark Wielaard for new Java library code and his work integrating
+ with Classpath.
+
+ * Dale Wiles helped port GCC to the Tahoe.
+
+ * Bob Wilson from Tensilica, Inc. for the Xtensa port.
+
+ * Jim Wilson for his direction via the steering committee, tackling
+ hard problems in various places that nobody else wanted to work
+ on, strength reduction and other loop optimizations.
+
+ * Carlo Wood for various fixes.
+
+ * Tom Wood for work on the m88k port.
+
+ * Masanobu Yuhara of Fujitsu Laboratories implemented the machine
+ description for the Tron architecture (specifically, the Gmicro).
+
+ * Kevin Zachmann helped ported GCC to the Tahoe.
+
+ * Gilles Zunino for help porting Java to Irix.
+
+
+ We'd also like to thank the folks who have contributed time and
+energy in testing GCC:
+
+ * Michael Abd-El-Malek
+
+ * Thomas Arend
+
+ * Bonzo Armstrong
+
+ * Steven Ashe
+
+ * Chris Baldwin
+
+ * David Billinghurst
+
+ * Jim Blandy
+
+ * Stephane Bortzmeyer
+
+ * Horst von Brand
+
+ * Frank Braun
+
+ * Rodney Brown
+
+ * Joe Buck
+
+ * Craig Burley
+
+ * Sidney Cadot
+
+ * Bradford Castalia
+
+ * Ralph Doncaster
+
+ * Ulrich Drepper
+
+ * David Edelsohn
+
+ * Richard Emberson
+
+ * Levente Farkas
+
+ * Graham Fawcett
+
+ * Robert A. French
+
+ * Jo"rgen Freyh
+
+ * Mark K. Gardner
+
+ * Charles-Antoine Gauthier
+
+ * Yung Shing Gene
+
+ * Kaveh Ghazi
+
+ * David Gilbert
+
+ * Simon Gornall
+
+ * Fred Gray
+
+ * John Griffin
+
+ * Patrik Hagglund
+
+ * Phil Hargett
+
+ * Amancio Hasty
+
+ * Bryan W. Headley
+
+ * Kate Hedstrom
+
+ * Richard Henderson
+
+ * Kevin B. Hendricks
+
+ * Manfred Hollstein
+
+ * Kamil Iskra
+
+ * Joep Jansen
+
+ * Christian Joensson
+
+ * David Kidd
+
+ * Tobias Kuipers
+
+ * Anand Krishnaswamy
+
+ * Jeff Law
+
+ * Robert Lipe
+
+ * llewelly
+
+ * Damon Love
+
+ * Dave Love
+
+ * H.J. Lu
+
+ * Brad Lucier
+
+ * Mumit Khan
+
+ * Matthias Klose
+
+ * Martin Knoblauch
+
+ * Jesse Macnish
+
+ * David Miller
+
+ * Toon Moene
+
+ * Stefan Morrell
+
+ * Anon A. Mous
+
+ * Matthias Mueller
+
+ * Pekka Nikander
+
+ * Alexandre Oliva
+
+ * Jon Olson
+
+ * Magnus Persson
+
+ * Chris Pollard
+
+ * Richard Polton
+
+ * David Rees
+
+ * Paul Reilly
+
+ * Tom Reilly
+
+ * Loren J. Rittle
+
+ * Torsten Rueger
+
+ * Danny Sadinoff
+
+ * Marc Schifer
+
+ * Peter Schmid
+
+ * David Schuler
+
+ * Vin Shelton
+
+ * Franz Sirl
+
+ * Tim Souder
+
+ * Mike Stump
+
+ * Adam Sulmicki
+
+ * George Talbot
+
+ * Gregory Warnes
+
+ * Carlo Wood
+
+ * David E. Young
+
+ * And many others
+
+ And finally we'd like to thank everyone who uses the compiler,
+submits bug reports and generally reminds us why we're doing this work
+in the first place.
+
+\1f
+File: gccint.info, Node: Option Index, Next: Index, Prev: Contributors, Up: Top
+
+Option Index
+************
+
+GCC's command line options are indexed here without any initial `-' or
+`--'. Where an option has both positive and negative forms (such as
+`-fOPTION' and `-fno-OPTION'), relevant entries in the manual are
+indexed under the most appropriate form; it may sometimes be useful to
+look up both forms.
+
+\0\b[index\0\b]
* Menu:
-* RTL Objects:: Expressions vs vectors vs strings vs integers.
-* RTL Classes:: Categories of RTL expression objects, and their structure.
-* Accessors:: Macros to access expression operands or vector elts.
-* Flags:: Other flags in an RTL expression.
-* Machine Modes:: Describing the size and format of a datum.
-* Constants:: Expressions with constant values.
-* Regs and Memory:: Expressions representing register contents or memory.
-* Arithmetic:: Expressions representing arithmetic on other expressions.
-* Comparisons:: Expressions representing comparison of expressions.
-* Bit-Fields:: Expressions representing bit-fields in memory or reg.
-* Vector Operations:: Expressions involving vector datatypes.
-* Conversions:: Extending, truncating, floating or fixing.
-* RTL Declarations:: Declaring volatility, constancy, etc.
-* Side Effects:: Expressions for storing in registers, etc.
-* Incdec:: Embedded side-effects for autoincrement addressing.
-* Assembler:: Representing `asm' with operands.
-* Insns:: Expression types for entire insns.
-* Calls:: RTL representation of function call insns.
-* Sharing:: Some expressions are unique; others *must* be copied.
-* Reading RTL:: Reading textual RTL from a file.
+* dB: Passes. (line 377)
+* dc: Passes. (line 286)
+* dd: Passes. (line 386)
+* dE: Passes. (line 295)
+* de: Passes. (line 187)
+* df: Passes. (line 274)
+* dg: Passes. (line 358)
+* dG: Passes. (line 239)
+* di: Passes. (line 142)
+* dj: Passes. (line 164)
+* dk: Passes. (line 402)
+* dl: Passes. (line 334)
+* dL: Passes. (line 251)
+* dN: Passes. (line 305)
+* dR: Passes. (line 365)
+* dr: Passes. (line 131)
+* dS: Passes. (line 321)
+* ds: Passes. (line 216)
+* dt: Passes. (line 260)
+* dW: Passes. (line 197)
+* dX: Passes. (line 206)
+* frerun-cse-after-loop: Passes. (line 255)
+* fssa: Passes. (line 178)
+* fssa-ccp: Passes. (line 190)
+* fssa-dce: Passes. (line 201)
+* fthread-jumps: Passes. (line 172)
+* msoft-float: Interface. (line 72)
\1f
-File: gccint.info, Node: RTL Objects, Next: RTL Classes, Up: RTL
-
-RTL Object Types
-================
-
- RTL uses five kinds of objects: expressions, integers, wide integers,
-strings and vectors. Expressions are the most important ones. An RTL
-expression ("RTX", for short) is a C structure, but it is usually
-referred to with a pointer; a type that is given the typedef name `rtx'.
-
- An integer is simply an `int'; their written form uses decimal
-digits. A wide integer is an integral object whose type is
-`HOST_WIDE_INT'; their written form uses decimal digits.
-
- A string is a sequence of characters. In core it is represented as a
-`char *' in usual C fashion, and it is written in C syntax as well.
-However, strings in RTL may never be null. If you write an empty
-string in a machine description, it is represented in core as a null
-pointer rather than as a pointer to a null character. In certain
-contexts, these null pointers instead of strings are valid. Within RTL
-code, strings are most commonly found inside `symbol_ref' expressions,
-but they appear in other contexts in the RTL expressions that make up
-machine descriptions.
-
- In a machine description, strings are normally written with double
-quotes, as you would in C. However, strings in machine descriptions may
-extend over many lines, which is invalid C, and adjacent string
-constants are not concatenated as they are in C. Any string constant
-may be surrounded with a single set of parentheses. Sometimes this
-makes the machine description easier to read.
-
- There is also a special syntax for strings, which can be useful when
-C code is embedded in a machine description. Wherever a string can
-appear, it is also valid to write a C-style brace block. The entire
-brace block, including the outermost pair of braces, is considered to be
-the string constant. Double quote characters inside the braces are not
-special. Therefore, if you write string constants in the C code, you
-need not escape each quote character with a backslash.
-
- A vector contains an arbitrary number of pointers to expressions.
-The number of elements in the vector is explicitly present in the
-vector. The written form of a vector consists of square brackets
-(`[...]') surrounding the elements, in sequence and with whitespace
-separating them. Vectors of length zero are not created; null pointers
-are used instead.
-
- Expressions are classified by "expression codes" (also called RTX
-codes). The expression code is a name defined in `rtl.def', which is
-also (in upper case) a C enumeration constant. The possible expression
-codes and their meanings are machine-independent. The code of an RTX
-can be extracted with the macro `GET_CODE (X)' and altered with
-`PUT_CODE (X, NEWCODE)'.
-
- The expression code determines how many operands the expression
-contains, and what kinds of objects they are. In RTL, unlike Lisp, you
-cannot tell by looking at an operand what kind of object it is.
-Instead, you must know from its context--from the expression code of
-the containing expression. For example, in an expression of code
-`subreg', the first operand is to be regarded as an expression and the
-second operand as an integer. In an expression of code `plus', there
-are two operands, both of which are to be regarded as expressions. In
-a `symbol_ref' expression, there is one operand, which is to be
-regarded as a string.
-
- Expressions are written as parentheses containing the name of the
-expression type, its flags and machine mode if any, and then the
-operands of the expression (separated by spaces).
-
- Expression code names in the `md' file are written in lower case,
-but when they appear in C code they are written in upper case. In this
-manual, they are shown as follows: `const_int'.
-
- In a few contexts a null pointer is valid where an expression is
-normally wanted. The written form of this is `(nil)'.
+File: gccint.info, Node: Index, Prev: Option Index, Up: Top
+
+Index
+*****
+
+\0\b[index\0\b]
+* Menu:
+
+* ! in constraint: Multi-Alternative. (line 47)
+* # in constraint: Modifiers. (line 60)
+* # in template: Output Template. (line 67)
+* #pragma: Misc. (line 298)
+* % in constraint: Modifiers. (line 45)
+* % in template: Output Template. (line 6)
+* & in constraint: Modifiers. (line 25)
+* (nil): RTL Objects. (line 73)
+* * in constraint: Modifiers. (line 65)
+* * in template: Output Statement. (line 29)
+* + in constraint: Modifiers. (line 12)
+* /c in RTL dump: Flags. (line 216)
+* /f in RTL dump: Flags. (line 222)
+* /i in RTL dump: Flags. (line 272)
+* /j in RTL dump: Flags. (line 285)
+* /s in RTL dump: Flags. (line 237)
+* /u in RTL dump: Flags. (line 299)
+* /v in RTL dump: Flags. (line 330)
+* 0 in constraint: Simple Constraints. (line 118)
+* < in constraint: Simple Constraints. (line 46)
+* = in constraint: Modifiers. (line 8)
+* > in constraint: Simple Constraints. (line 50)
+* ? in constraint: Multi-Alternative. (line 41)
+* \: Output Template. (line 47)
+* __builtin_args_info: Varargs. (line 41)
+* __builtin_classify_type: Varargs. (line 75)
+* __builtin_next_arg: Varargs. (line 65)
+* __builtin_saveregs: Varargs. (line 23)
+* __CTOR_LIST__: Initialization. (line 25)
+* __DTOR_LIST__: Initialization. (line 25)
+* __main: Collect2. (line 15)
+* abort: Portability. (line 20)
+* abs: Arithmetic. (line 165)
+* abs and attributes: Expressions. (line 64)
+* absM2 instruction pattern: Standard Names. (line 231)
+* absolute value: Arithmetic. (line 165)
+* access to operands: Accessors. (line 6)
+* accessors: Accessors. (line 6)
+* ACCUMULATE_OUTGOING_ARGS: Stack Arguments. (line 40)
+* ACCUMULATE_OUTGOING_ARGS and stack frames: Function Entry. (line 138)
+* ADA_LONG_TYPE_SIZE: Type Layout. (line 25)
+* ADDITIONAL_REGISTER_NAMES: Instruction Output. (line 14)
+* addM3 instruction pattern: Standard Names. (line 161)
+* addr_diff_vec: Side Effects. (line 293)
+* addr_diff_vec, length of: Insn Lengths. (line 26)
+* ADDR_EXPR: Expression trees. (line 6)
+* addr_vec: Side Effects. (line 288)
+* addr_vec, length of: Insn Lengths. (line 26)
+* address constraints: Simple Constraints. (line 152)
+* ADDRESS_COST: Costs. (line 48)
+* address_operand: Simple Constraints. (line 156)
+* addressing modes: Addressing Modes. (line 6)
+* addressof: Regs and Memory. (line 256)
+* ADJUST_FIELD_ALIGN: Storage Layout. (line 180)
+* ADJUST_INSN_LENGTH: Insn Lengths. (line 40)
+* aggregates as return values: Aggregate Return. (line 6)
+* ALL_REGS: Register Classes. (line 17)
+* ALLOCATE_INITIAL_VALUE: Misc. (line 556)
+* allocate_stack instruction pattern: Standard Names. (line 729)
+* ALLOCATE_TRAMPOLINE: Trampolines. (line 71)
+* analysis, data flow: Passes. (line 264)
+* and: Arithmetic. (line 132)
+* and and attributes: Expressions. (line 50)
+* and, canonicalization of: Insn Canonicalizations.
+ (line 42)
+* andM3 instruction pattern: Standard Names. (line 167)
+* APPLY_RESULT_SIZE: Scalar Return. (line 88)
+* ARG_POINTER_CFA_OFFSET: Frame Layout. (line 136)
+* ARG_POINTER_REGNUM: Frame Registers. (line 40)
+* ARG_POINTER_REGNUM and virtual registers: Regs and Memory. (line 65)
+* arg_pointer_rtx: Frame Registers. (line 85)
+* ARGS_GROW_DOWNWARD: Frame Layout. (line 34)
+* argument passing: Interface. (line 37)
+* arguments in registers: Register Arguments. (line 6)
+* arguments on stack: Stack Arguments. (line 6)
+* arithmetic libraries: Interface. (line 72)
+* arithmetic shift: Arithmetic. (line 147)
+* arithmetic simplifications: Passes. (line 86)
+* arithmetic, in RTL: Arithmetic. (line 6)
+* ARITHMETIC_TYPE_P: Types. (line 77)
+* array: Types. (line 6)
+* ARRAY_REF: Expression trees. (line 6)
+* ARRAY_TYPE: Types. (line 6)
+* ashift: Arithmetic. (line 147)
+* ashift and attributes: Expressions. (line 64)
+* ashiftrt: Arithmetic. (line 155)
+* ashiftrt and attributes: Expressions. (line 64)
+* ashlM3 instruction pattern: Standard Names. (line 217)
+* ashrM3 instruction pattern: Standard Names. (line 224)
+* ASM_APP_OFF: File Framework. (line 43)
+* ASM_APP_ON: File Framework. (line 36)
+* ASM_CLOBBERS: Function Bodies. (line 6)
+* ASM_COMMENT_START: File Framework. (line 31)
+* ASM_CV_QUAL: Function Bodies. (line 6)
+* ASM_DECLARE_CLASS_REFERENCE: Label Output. (line 298)
+* ASM_DECLARE_FUNCTION_NAME: Label Output. (line 15)
+* ASM_DECLARE_FUNCTION_SIZE: Label Output. (line 26)
+* ASM_DECLARE_OBJECT_NAME: Label Output. (line 36)
+* ASM_DECLARE_REGISTER_GLOBAL: Label Output. (line 47)
+* ASM_DECLARE_UNRESOLVED_REFERENCE: Label Output. (line 304)
+* ASM_FILE_END: File Framework. (line 20)
+* ASM_FILE_START: File Framework. (line 8)
+* ASM_FINAL_SPEC: Driver. (line 144)
+* ASM_FINISH_DECLARE_OBJECT: Label Output. (line 55)
+* ASM_FORMAT_PRIVATE_NAME: Label Output. (line 221)
+* asm_fprintf: Instruction Output. (line 129)
+* ASM_FPRINTF_EXTENSIONS: Instruction Output. (line 140)
+* ASM_GENERATE_INTERNAL_LABEL: Label Output. (line 205)
+* ASM_GLOBALIZE_LABEL: Label Output. (line 65)
+* asm_input: Side Effects. (line 275)
+* ASM_INPUTS: Function Bodies. (line 6)
+* ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX: Exception Handling. (line 69)
+* ASM_NO_SKIP_IN_TEXT: Alignment Output. (line 71)
+* asm_noperands: Insns. (line 260)
+* asm_operands, RTL sharing: Sharing. (line 45)
+* asm_operands, usage: Assembler. (line 6)
+* ASM_OUTPUT_ADDR_DIFF_ELT: Dispatch Tables. (line 8)
+* ASM_OUTPUT_ADDR_VEC_ELT: Dispatch Tables. (line 25)
+* ASM_OUTPUT_ALIGN: Alignment Output. (line 78)
+* ASM_OUTPUT_ALIGNED_BSS: Uninitialized Data. (line 62)
+* ASM_OUTPUT_ALIGNED_COMMON: Uninitialized Data. (line 22)
+* ASM_OUTPUT_ALIGNED_DECL_COMMON: Uninitialized Data. (line 29)
+* ASM_OUTPUT_ALIGNED_DECL_LOCAL: Uninitialized Data. (line 97)
+* ASM_OUTPUT_ALIGNED_LOCAL: Uninitialized Data. (line 90)
+* ASM_OUTPUT_ALTERNATE_LABEL_NAME: Label Output. (line 197)
+* ASM_OUTPUT_ASCII: Data Output. (line 49)
+* ASM_OUTPUT_BSS: Uninitialized Data. (line 42)
+* ASM_OUTPUT_CASE_END: Dispatch Tables. (line 50)
+* ASM_OUTPUT_CASE_LABEL: Dispatch Tables. (line 37)
+* ASM_OUTPUT_COMMON: Uninitialized Data. (line 9)
+* ASM_OUTPUT_DEBUG_LABEL: Label Output. (line 185)
+* ASM_OUTPUT_DEF: Label Output. (line 239)
+* ASM_OUTPUT_DEF_FROM_DECLS: Label Output. (line 246)
+* ASM_OUTPUT_DEFINE_LABEL_DIFFERENCE_SYMBOL: Label Output. (line 253)
+* ASM_OUTPUT_EXTERNAL: Label Output. (line 124)
+* ASM_OUTPUT_EXTERNAL_LIBCALL: Label Output. (line 134)
+* ASM_OUTPUT_FDESC: Data Output. (line 58)
+* ASM_OUTPUT_IDENT: File Framework. (line 73)
+* ASM_OUTPUT_INTERNAL_LABEL: Label Output. (line 167)
+* ASM_OUTPUT_LABEL: Label Output. (line 8)
+* ASM_OUTPUT_LABEL_REF: Label Output. (line 158)
+* ASM_OUTPUT_LABELREF: Label Output. (line 144)
+* ASM_OUTPUT_LOCAL: Uninitialized Data. (line 77)
+* ASM_OUTPUT_MAX_SKIP_ALIGN: Alignment Output. (line 83)
+* ASM_OUTPUT_MI_THUNK: Function Entry. (line 200)
+* ASM_OUTPUT_OPCODE: Instruction Output. (line 20)
+* ASM_OUTPUT_POOL_EPILOGUE: Data Output. (line 113)
+* ASM_OUTPUT_POOL_PROLOGUE: Data Output. (line 71)
+* ASM_OUTPUT_REG_POP: Instruction Output. (line 183)
+* ASM_OUTPUT_REG_PUSH: Instruction Output. (line 178)
+* ASM_OUTPUT_SHARED_BSS: Uninitialized Data. (line 72)
+* ASM_OUTPUT_SHARED_COMMON: Uninitialized Data. (line 37)
+* ASM_OUTPUT_SHARED_LOCAL: Uninitialized Data. (line 105)
+* ASM_OUTPUT_SKIP: Alignment Output. (line 65)
+* ASM_OUTPUT_SOURCE_FILENAME: File Framework. (line 50)
+* ASM_OUTPUT_SOURCE_LINE: File Framework. (line 65)
+* ASM_OUTPUT_SPECIAL_POOL_ENTRY: Data Output. (line 82)
+* ASM_OUTPUT_SYMBOL_REF: Label Output. (line 151)
+* ASM_OUTPUT_WEAK_ALIAS: Label Output. (line 264)
+* ASM_OUTPUTS: Function Bodies. (line 6)
+* ASM_PREFERRED_EH_DATA_FORMAT: Exception Handling. (line 55)
+* ASM_SPEC: Driver. (line 136)
+* ASM_STABD_OP: DBX Options. (line 35)
+* ASM_STABN_OP: DBX Options. (line 42)
+* ASM_STABS_OP: DBX Options. (line 28)
+* ASM_STMT: Function Bodies. (line 6)
+* ASM_STRING: Function Bodies. (line 6)
+* ASM_WEAKEN_DECL: Label Output. (line 86)
+* ASM_WEAKEN_LABEL: Label Output. (line 73)
+* assemble_name: Label Output. (line 8)
+* assembler format: File Framework. (line 6)
+* assembler instructions in RTL: Assembler. (line 6)
+* ASSEMBLER_DIALECT: Instruction Output. (line 151)
+* assigning attribute values to insns: Tagging Insns. (line 6)
+* assignment operator: Function Basics. (line 6)
+* asterisk in template: Output Statement. (line 29)
+* atof: Cross-compilation. (line 12)
+* attr <1>: Tagging Insns. (line 54)
+* attr: Expressions. (line 154)
+* attr_flag: Expressions. (line 119)
+* attribute expressions: Expressions. (line 6)
+* attribute specifications: Attr Example. (line 6)
+* attribute specifications example: Attr Example. (line 6)
+* attributes: Attributes. (line 6)
+* attributes, defining: Defining Attributes. (line 6)
+* attributes, target-specific: Target Attributes. (line 6)
+* autoincrement addressing, availability: Portability. (line 20)
+* autoincrement/decrement addressing: Simple Constraints. (line 28)
+* autoincrement/decrement analysis: Passes. (line 270)
+* AVOID_CCMODE_COPIES: Values in Registers. (line 98)
+* backslash: Output Template. (line 47)
+* barrier: Insns. (line 150)
+* BASE_REG_CLASS: Register Classes. (line 106)
+* basic block reordering: Passes. (line 369)
+* basic blocks: Passes. (line 264)
+* bCOND instruction pattern: Standard Names. (line 444)
+* bcopy, implicit usage: Library Calls. (line 99)
+* BIGGEST_ALIGNMENT: Storage Layout. (line 162)
+* BIGGEST_FIELD_ALIGNMENT: Storage Layout. (line 173)
+* BImode: Machine Modes. (line 22)
+* BIND_EXPR: Expression trees. (line 6)
+* BINFO_TYPE: Classes. (line 6)
+* bit-fields: Bit-Fields. (line 6)
+* BIT_AND_EXPR: Expression trees. (line 6)
+* BIT_IOR_EXPR: Expression trees. (line 6)
+* BIT_NOT_EXPR: Expression trees. (line 6)
+* BIT_XOR_EXPR: Expression trees. (line 6)
+* BITFIELD_NBYTES_LIMITED: Storage Layout. (line 315)
+* BITS_BIG_ENDIAN: Storage Layout. (line 11)
+* BITS_BIG_ENDIAN, effect on sign_extract: Bit-Fields. (line 11)
+* BITS_PER_UNIT: Storage Layout. (line 51)
+* BITS_PER_WORD: Storage Layout. (line 55)
+* bitwise complement: Arithmetic. (line 128)
+* bitwise exclusive-or: Arithmetic. (line 142)
+* bitwise inclusive-or: Arithmetic. (line 137)
+* bitwise logical-and: Arithmetic. (line 132)
+* BLKmode: Machine Modes. (line 97)
+* BLKmode, and function return values: Calls. (line 23)
+* BOOL_TYPE_SIZE: Type Layout. (line 57)
+* BOOLEAN_TYPE: Types. (line 6)
+* branch shortening: Passes. (line 390)
+* BRANCH_COST: Costs. (line 132)
+* break_out_memory_refs: Addressing Modes. (line 156)
+* BREAK_STMT: Function Bodies. (line 6)
+* BSS_SECTION_ASM_OP: Sections. (line 39)
+* builtin_longjmp instruction pattern: Standard Names. (line 826)
+* BUILTIN_SETJMP_FRAME_VALUE: Frame Layout. (line 89)
+* builtin_setjmp_receiver instruction pattern: Standard Names.
+ (line 816)
+* builtin_setjmp_setup instruction pattern: Standard Names. (line 805)
+* byte_mode: Machine Modes. (line 223)
+* BYTES_BIG_ENDIAN: Storage Layout. (line 23)
+* BYTES_BIG_ENDIAN, effect on subreg: Regs and Memory. (line 136)
+* bzero, implicit usage: Library Calls. (line 99)
+* C statements for assembler output: Output Statement. (line 6)
+* C/C++ Internal Representation: Trees. (line 6)
+* C4X_FLOAT_FORMAT: Storage Layout. (line 410)
+* call <1>: Side Effects. (line 81)
+* call: Flags. (line 216)
+* call instruction pattern: Standard Names. (line 471)
+* call usage: Calls. (line 10)
+* call, in insn_list: Flags. (line 64)
+* call-clobbered register: Register Basics. (line 35)
+* call-saved register: Register Basics. (line 35)
+* call-used register: Register Basics. (line 35)
+* CALL_EXPR: Expression trees. (line 6)
+* call_insn: Insns. (line 94)
+* call_insn and /j: Flags. (line 176)
+* call_insn and /u: Flags. (line 19)
+* CALL_INSN_FUNCTION_USAGE: Insns. (line 100)
+* call_pop instruction pattern: Standard Names. (line 499)
+* CALL_POPS_ARGS: Stack Arguments. (line 149)
+* CALL_REALLY_USED_REGISTERS: Register Basics. (line 45)
+* CALL_USED_REGISTERS: Register Basics. (line 34)
+* call_used_regs: Register Basics. (line 59)
+* call_value instruction pattern: Standard Names. (line 491)
+* call_value_pop instruction pattern: Standard Names. (line 499)
+* CALLER_SAVE_PROFITABLE: Caller Saves. (line 18)
+* calling conventions: Stack and Calling. (line 6)
+* calling functions in RTL: Calls. (line 6)
+* CAN_DEBUG_WITHOUT_FP: Run-time Target. (line 161)
+* CAN_ELIMINATE: Elimination. (line 70)
+* canadian: Configure Terms. (line 6)
+* canonicalization of instructions: Insn Canonicalizations.
+ (line 6)
+* CANONICALIZE_COMPARISON: Condition Code. (line 99)
+* canonicalize_funcptr_for_compare instruction pattern: Standard Names.
+ (line 660)
+* CASE_DROPS_THROUGH: Misc. (line 64)
+* CASE_VALUES_THRESHOLD: Misc. (line 69)
+* CASE_VECTOR_MODE: Misc. (line 46)
+* CASE_VECTOR_PC_RELATIVE: Misc. (line 59)
+* CASE_VECTOR_SHORTEN_MODE: Misc. (line 50)
+* casesi instruction pattern: Standard Names. (line 579)
+* cc0: Regs and Memory. (line 182)
+* cc0, RTL sharing: Sharing. (line 27)
+* cc0_rtx: Regs and Memory. (line 208)
+* CC1_SPEC: Driver. (line 118)
+* CC1PLUS_SPEC: Driver. (line 126)
+* cc_status: Condition Code. (line 8)
+* CC_STATUS_MDEP: Condition Code. (line 18)
+* CC_STATUS_MDEP_INIT: Condition Code. (line 24)
+* CCmode: Machine Modes. (line 90)
+* CDImode: Machine Modes. (line 116)
+* change_address: Standard Names. (line 47)
+* CHAR_TYPE_SIZE: Type Layout. (line 45)
+* CHECK_FLOAT_VALUE: Storage Layout. (line 382)
+* check_stack instruction pattern: Standard Names. (line 758)
+* CHImode: Machine Modes. (line 116)
+* class: Classes. (line 6)
+* class definitions, register: Register Classes. (line 6)
+* class preference constraints: Class Preferences. (line 6)
+* CLASS_LIKELY_SPILLED_P: Register Classes. (line 325)
+* CLASS_MAX_NREGS: Register Classes. (line 342)
+* CLASS_TYPE_P: Types. (line 81)
+* classes of RTX codes: RTL Classes. (line 6)
+* CLASSTYPE_DECLARED_CLASS: Classes. (line 6)
+* CLASSTYPE_HAS_MUTABLE: Classes. (line 78)
+* CLASSTYPE_NON_POD_P: Classes. (line 84)
+* CLEANUP_DECL: Function Bodies. (line 6)
+* CLEANUP_EXPR: Function Bodies. (line 6)
+* CLEANUP_POINT_EXPR: Expression trees. (line 6)
+* CLEANUP_STMT: Function Bodies. (line 6)
+* CLEAR_INSN_CACHE: Trampolines. (line 124)
+* clobber: Side Effects. (line 95)
+* clrstrM instruction pattern: Standard Names. (line 299)
+* cmpM instruction pattern: Standard Names. (line 253)
+* cmpstrM instruction pattern: Standard Names. (line 312)
+* code generation RTL sequences: Expander Definitions.
+ (line 6)
+* code motion: Passes. (line 243)
+* code_label: Insns. (line 125)
+* code_label and /i: Flags. (line 53)
+* CODE_LABEL_NUMBER: Insns. (line 125)
+* codes, RTL expression: RTL Objects. (line 47)
+* COImode: Machine Modes. (line 116)
+* COLLECT2_HOST_INITIALIZATION: Host Config. (line 87)
+* COLLECT_EXPORT_LIST: Misc. (line 584)
+* combiner pass: Regs and Memory. (line 148)
+* common subexpression elimination: Passes. (line 210)
+* compare: Arithmetic. (line 42)
+* compare, canonicalization of: Insn Canonicalizations.
+ (line 25)
+* compiler passes and files: Passes. (line 6)
+* complement, bitwise: Arithmetic. (line 128)
+* COMPLEX_CST: Expression trees. (line 6)
+* COMPLEX_EXPR: Expression trees. (line 6)
+* COMPLEX_TYPE: Types. (line 6)
+* COMPONENT_REF: Expression trees. (line 6)
+* COMPOUND_BODY: Function Bodies. (line 6)
+* COMPOUND_EXPR: Expression trees. (line 6)
+* COMPOUND_LITERAL_EXPR: Expression trees. (line 6)
+* COMPOUND_LITERAL_EXPR_DECL: Expression trees. (line 449)
+* COMPOUND_LITERAL_EXPR_DECL_STMT: Expression trees. (line 449)
+* COMPOUND_STMT: Function Bodies. (line 6)
+* computing the length of an insn: Insn Lengths. (line 6)
+* cond: Comparisons. (line 87)
+* cond and attributes: Expressions. (line 37)
+* cond_exec: Side Effects. (line 239)
+* COND_EXPR: Expression trees. (line 6)
+* condition code register: Regs and Memory. (line 182)
+* condition code status: Condition Code. (line 6)
+* condition codes: Comparisons. (line 17)
+* conditional constant propagation: Passes. (line 190)
+* Conditional Constant Propagation, SSA based: Passes. (line 190)
+* conditional execution: Conditional Execution.
+ (line 6)
+* CONDITIONAL_REGISTER_USAGE: Register Basics. (line 59)
+* conditional_trap instruction pattern: Standard Names. (line 893)
+* conditions, in patterns: Patterns. (line 44)
+* configuration file: Host Config. (line 6)
+* configure terms: Configure Terms. (line 6)
+* CONJ_EXPR: Expression trees. (line 6)
+* CONST0_RTX: Constants. (line 70)
+* const0_rtx: Constants. (line 13)
+* CONST1_RTX: Constants. (line 70)
+* const1_rtx: Constants. (line 13)
+* CONST2_RTX: Constants. (line 70)
+* const2_rtx: Constants. (line 13)
+* CONST_COSTS: Costs. (line 9)
+* CONST_DECL: Declarations. (line 6)
+* const_double: Constants. (line 29)
+* const_double, RTL sharing: Sharing. (line 29)
+* CONST_DOUBLE_CHAIN: Constants. (line 48)
+* CONST_DOUBLE_LOW: Constants. (line 57)
+* CONST_DOUBLE_MEM: Constants. (line 48)
+* CONST_DOUBLE_OK_FOR_LETTER_P: Register Classes. (line 387)
+* const_int: Constants. (line 8)
+* const_int and attribute tests: Expressions. (line 47)
+* const_int and attributes: Expressions. (line 10)
+* const_int, RTL sharing: Sharing. (line 23)
+* CONST_OK_FOR_LETTER_P: Register Classes. (line 378)
+* CONST_OR_PURE_CALL_P: Flags. (line 19)
+* const_string: Constants. (line 79)
+* const_string and attributes: Expressions. (line 20)
+* const_true_rtx: Constants. (line 23)
+* const_vector: Constants. (line 36)
+* const_vector, RTL sharing: Sharing. (line 32)
+* constant attributes: Constant Attributes. (line 6)
+* constant definitions: Constant Definitions.
+ (line 6)
+* constant folding: Passes. (line 86)
+* constant folding and floating point: Cross-compilation. (line 93)
+* constant propagation: Passes. (line 210)
+* CONSTANT_ADDRESS_P: Addressing Modes. (line 28)
+* CONSTANT_AFTER_FUNCTION_P: Data Output. (line 107)
+* CONSTANT_ALIGNMENT: Storage Layout. (line 207)
+* CONSTANT_P: Addressing Modes. (line 34)
+* CONSTANT_POOL_ADDRESS_P: Flags. (line 10)
+* CONSTANT_POOL_BEFORE_FUNCTION: Data Output. (line 63)
+* constants in constraints: Simple Constraints. (line 58)
+* constm1_rtx: Constants. (line 13)
+* constraint modifier characters: Modifiers. (line 6)
+* constraint, matching: Simple Constraints. (line 130)
+* constraints: Constraints. (line 6)
+* constraints, machine specific: Machine Constraints. (line 6)
+* CONSTRUCTOR: Expression trees. (line 6)
+* constructor: Function Basics. (line 6)
+* constructors, automatic calls: Collect2. (line 15)
+* constructors, output of: Initialization. (line 6)
+* container: Containers. (line 6)
+* CONTINUE_STMT: Function Bodies. (line 6)
+* contributors: Contributors. (line 6)
+* controlling register usage: Register Basics. (line 76)
+* controlling the compilation driver: Driver. (line 6)
+* conventions, run-time: Interface. (line 6)
+* conversions: Conversions. (line 6)
+* CONVERT_EXPR: Expression trees. (line 6)
+* copy constructor: Function Basics. (line 6)
+* copy propagation: Passes. (line 220)
+* copy_rtx: Addressing Modes. (line 207)
+* copy_rtx_if_shared: Sharing. (line 64)
+* costs of instructions: Costs. (line 6)
+* COSTS_N_INSNS: Costs. (line 23)
+* CP_INTEGRAL_TYPE: Types. (line 73)
+* cp_namespace_decls: Namespaces. (line 44)
+* CP_TYPE_CONST_NON_VOLATILE_P: Types. (line 46)
+* CP_TYPE_CONST_P: Types. (line 37)
+* CP_TYPE_QUALS: Types. (line 6)
+* CP_TYPE_RESTRICT_P: Types. (line 43)
+* CP_TYPE_VOLATILE_P: Types. (line 40)
+* CPLUSPLUS_CPP_SPEC: Driver. (line 77)
+* CPP_PREDEFINES: Run-time Target. (line 8)
+* cpp_register_pragma: Misc. (line 322)
+* CPP_SPEC: Driver. (line 70)
+* CQImode: Machine Modes. (line 116)
+* cross compilation and floating point: Cross-compilation. (line 6)
+* CRT_CALL_STATIC_FUNCTION: Sections. (line 66)
+* CRTSTUFF_T_CFLAGS: Target Fragment. (line 35)
+* CRTSTUFF_T_CFLAGS_S: Target Fragment. (line 39)
+* CSImode: Machine Modes. (line 116)
+* CTImode: Machine Modes. (line 116)
+* CUMULATIVE_ARGS: Register Arguments. (line 131)
+* current_function_epilogue_delay_list: Function Entry. (line 189)
+* current_function_is_leaf: Leaf Functions. (line 51)
+* current_function_outgoing_args_size: Stack Arguments. (line 40)
+* current_function_pops_args: Function Entry. (line 106)
+* current_function_pretend_args_size: Function Entry. (line 112)
+* current_function_uses_only_leaf_regs: Leaf Functions. (line 51)
+* current_insn_predicate: Conditional Execution.
+ (line 26)
+* cycle_display instruction pattern: Standard Names. (line 922)
+* data flow analysis: Passes. (line 264)
+* data structures: Per-Function Data. (line 6)
+* DATA_ALIGNMENT: Storage Layout. (line 194)
+* data_section: Sections. (line 88)
+* DATA_SECTION_ASM_OP: Sections. (line 28)
+* DBR_OUTPUT_SEQEND: Instruction Output. (line 111)
+* dbr_sequence_length: Instruction Output. (line 111)
+* DBX_BLOCKS_FUNCTION_RELATIVE: DBX Options. (line 112)
+* DBX_CONTIN_CHAR: DBX Options. (line 65)
+* DBX_CONTIN_LENGTH: DBX Options. (line 55)
+* DBX_DEBUGGING_INFO: DBX Options. (line 8)
+* DBX_FUNCTION_FIRST: DBX Options. (line 100)
+* DBX_LBRAC_FIRST: DBX Options. (line 106)
+* DBX_MEMPARM_STABS_LETTER: DBX Options. (line 96)
+* DBX_NO_XREFS: DBX Options. (line 49)
+* DBX_OUTPUT_ENUM: DBX Hooks. (line 21)
+* DBX_OUTPUT_FUNCTION_END: DBX Hooks. (line 27)
+* DBX_OUTPUT_LBRAC: DBX Hooks. (line 8)
+* DBX_OUTPUT_MAIN_SOURCE_DIRECTORY: File Names and DBX. (line 24)
+* DBX_OUTPUT_MAIN_SOURCE_FILE_END: File Names and DBX. (line 32)
+* DBX_OUTPUT_MAIN_SOURCE_FILENAME: File Names and DBX. (line 15)
+* DBX_OUTPUT_NFUN: DBX Hooks. (line 17)
+* DBX_OUTPUT_RBRAC: DBX Hooks. (line 14)
+* DBX_OUTPUT_SOURCE_FILENAME: File Names and DBX. (line 39)
+* DBX_OUTPUT_STANDARD_TYPES: DBX Hooks. (line 34)
+* DBX_REGISTER_NUMBER: All Debuggers. (line 8)
+* DBX_REGPARM_STABS_CODE: DBX Options. (line 86)
+* DBX_REGPARM_STABS_LETTER: DBX Options. (line 91)
+* DBX_STATIC_CONST_VAR_CODE: DBX Options. (line 81)
+* DBX_STATIC_STAB_DATA_SECTION: DBX Options. (line 72)
+* DBX_TYPE_DECL_STABS_CODE: DBX Options. (line 77)
+* DBX_USE_BINCL: DBX Options. (line 117)
+* DBX_WORKING_DIRECTORY: File Names and DBX. (line 8)
+* DCE, SSA based: Passes. (line 201)
+* DCmode: Machine Modes. (line 111)
+* De Morgan's law: Insn Canonicalizations.
+ (line 42)
+* dead code: Passes. (line 146)
+* dead code elimination: Passes. (line 201)
+* dead_or_set_p: define_peephole. (line 65)
+* DEBUG_SYMS_TEXT: DBX Options. (line 24)
+* DEBUGGER_ARG_OFFSET: All Debuggers. (line 36)
+* DEBUGGER_AUTO_OFFSET: All Debuggers. (line 27)
+* debugging information generation: Passes. (line 418)
+* DECL_ALIGN: Declarations. (line 6)
+* DECL_ANTICIPATED: Function Basics. (line 41)
+* DECL_ARGUMENTS: Function Basics. (line 156)
+* DECL_ARRAY_DELETE_OPERATOR_P: Function Basics. (line 177)
+* DECL_ARTIFICIAL <1>: Function Basics. (line 6)
+* DECL_ARTIFICIAL: Declarations. (line 29)
+* DECL_ASSEMBLER_NAME: Function Basics. (line 6)
+* DECL_ATTRIBUTES: Attributes. (line 22)
+* DECL_BASE_CONSTRUCTOR_P: Function Basics. (line 87)
+* DECL_CLASS_SCOPE_P: Declarations. (line 46)
+* DECL_COMPLETE_CONSTRUCTOR_P: Function Basics. (line 83)
+* DECL_COMPLETE_DESTRUCTOR_P: Function Basics. (line 97)
+* DECL_CONST_MEMFUNC_P: Function Basics. (line 70)
+* DECL_CONSTRUCTOR_P: Function Basics. (line 6)
+* DECL_CONTEXT: Namespaces. (line 26)
+* DECL_CONV_FN_P: Function Basics. (line 6)
+* DECL_COPY_CONSTRUCTOR_P: Function Basics. (line 91)
+* DECL_DESTRUCTOR_P: Function Basics. (line 6)
+* DECL_EXTERN_C_FUNCTION_P: Function Basics. (line 45)
+* DECL_EXTERNAL <1>: Function Basics. (line 31)
+* DECL_EXTERNAL: Declarations. (line 6)
+* DECL_FUNCTION_MEMBER_P: Function Basics. (line 6)
+* DECL_FUNCTION_SCOPE_P: Declarations. (line 49)
+* DECL_GLOBAL_CTOR_P: Function Basics. (line 6)
+* DECL_GLOBAL_DTOR_P: Function Basics. (line 6)
+* DECL_INITIAL: Declarations. (line 6)
+* DECL_LINKONCE_P: Function Basics. (line 6)
+* DECL_LOCAL_FUNCTION_P: Function Basics. (line 37)
+* DECL_MAIN_P: Function Basics. (line 7)
+* DECL_NAME <1>: Function Basics. (line 6)
+* DECL_NAME <2>: Declarations. (line 12)
+* DECL_NAME: Namespaces. (line 15)
+* DECL_NAMESPACE_ALIAS: Namespaces. (line 30)
+* DECL_NAMESPACE_SCOPE_P: Declarations. (line 42)
+* DECL_NAMESPACE_STD_P: Namespaces. (line 40)
+* DECL_NON_THUNK_FUNCTION_P: Function Basics. (line 137)
+* DECL_NONCONVERTING_P: Function Basics. (line 79)
+* DECL_NONSTATIC_MEMBER_FUNCTION_P: Function Basics. (line 67)
+* DECL_OVERLOADED_OPERATOR_P: Function Basics. (line 6)
+* DECL_RESULT: Function Basics. (line 161)
+* DECL_SIZE: Declarations. (line 6)
+* DECL_SOURCE_FILE: Declarations. (line 19)
+* DECL_SOURCE_LINE: Declarations. (line 25)
+* DECL_STATIC_FUNCTION_P: Function Basics. (line 64)
+* DECL_STMT: Function Bodies. (line 6)
+* DECL_STMT_DECL: Function Bodies. (line 6)
+* DECL_THUNK_P: Function Basics. (line 115)
+* DECL_VOLATILE_MEMFUNC_P: Function Basics. (line 73)
+* declaration: Declarations. (line 6)
+* declarations, RTL: RTL Declarations. (line 6)
+* decrement_and_branch_until_zero instruction pattern: Standard Names.
+ (line 622)
+* DEFAULT_CALLER_SAVES: Caller Saves. (line 10)
+* DEFAULT_GDB_EXTENSIONS: DBX Options. (line 17)
+* DEFAULT_MAIN_RETURN: Misc. (line 396)
+* DEFAULT_PCC_STRUCT_RETURN: Aggregate Return. (line 33)
+* DEFAULT_RTX_COSTS: Costs. (line 34)
+* DEFAULT_SHORT_ENUMS: Type Layout. (line 99)
+* DEFAULT_SIGNED_CHAR: Type Layout. (line 93)
+* define_asm_attributes: Tagging Insns. (line 73)
+* define_attr: Defining Attributes. (line 6)
+* define_cond_exec: Conditional Execution.
+ (line 13)
+* define_constants: Constant Definitions.
+ (line 6)
+* define_delay: Delay Slots. (line 25)
+* define_expand: Expander Definitions.
+ (line 11)
+* define_function_unit: Function Units. (line 33)
+* define_insn: Patterns. (line 6)
+* define_insn example: Example. (line 6)
+* define_insn_and_split: Insn Splitting. (line 170)
+* define_peephole: define_peephole. (line 6)
+* define_peephole2: define_peephole2. (line 6)
+* define_split: Insn Splitting. (line 32)
+* defining attributes and their values: Defining Attributes. (line 6)
+* defining jump instruction patterns: Jump Patterns. (line 6)
+* defining looping instruction patterns: Looping Patterns. (line 6)
+* defining peephole optimizers: Peephole Definitions.
+ (line 6)
+* defining RTL sequences for code generation: Expander Definitions.
+ (line 6)
+* delay slots, defining: Delay Slots. (line 6)
+* DELAY_SLOTS_FOR_EPILOGUE: Function Entry. (line 170)
+* delayed branch scheduling: Passes. (line 381)
+* Dependent Patterns: Dependent Patterns. (line 6)
+* destructor: Function Basics. (line 6)
+* destructors, output of: Initialization. (line 6)
+* DFmode: Machine Modes. (line 73)
+* digits in constraint: Simple Constraints. (line 118)
+* DImode: Machine Modes. (line 45)
+* DIR_SEPARATOR: Host Config. (line 58)
+* DIR_SEPARATOR_2: Host Config. (line 59)
+* directory options .md: Including Patterns. (line 45)
+* disabling certain registers: Register Basics. (line 76)
+* dispatch table: Dispatch Tables. (line 8)
+* div: Arithmetic. (line 99)
+* div and attributes: Expressions. (line 64)
+* DIVDI3_LIBCALL: Library Calls. (line 44)
+* division: Arithmetic. (line 99)
+* divM3 instruction pattern: Standard Names. (line 167)
+* divmodM4 instruction pattern: Standard Names. (line 197)
+* DIVSI3_LIBCALL: Library Calls. (line 14)
+* DO_BODY: Function Bodies. (line 6)
+* DO_COND: Function Bodies. (line 6)
+* DO_STMT: Function Bodies. (line 6)
+* DOLLARS_IN_IDENTIFIERS: Misc. (line 377)
+* doloop_begin instruction pattern: Standard Names. (line 653)
+* doloop_end instruction pattern: Standard Names. (line 632)
+* DONE: Expander Definitions.
+ (line 74)
+* DONT_REDUCE_ADDR: Costs. (line 171)
+* DOUBLE_TYPE_SIZE: Type Layout. (line 66)
+* driver: Driver. (line 6)
+* DUMPFILE_FORMAT: Host Config. (line 104)
+* DWARF2_ASM_LINE_DEBUG_INFO: SDB and DWARF. (line 46)
+* DWARF2_DEBUGGING_INFO: SDB and DWARF. (line 16)
+* DWARF2_FRAME_INFO: SDB and DWARF. (line 26)
+* DWARF2_GENERATE_TEXT_SECTION_LABEL: SDB and DWARF. (line 39)
+* DWARF2_UNWIND_INFO: Exception Region Output.
+ (line 33)
+* DWARF_CIE_DATA_ALIGNMENT: Exception Region Output.
+ (line 48)
+* DWARF_DEBUGGING_INFO: SDB and DWARF. (line 12)
+* DWARF_FRAME_REGISTERS: Frame Registers. (line 92)
+* DYNAMIC_CHAIN_ADDRESS: Frame Layout. (line 72)
+* E in constraint: Simple Constraints. (line 77)
+* earlyclobber operand: Modifiers. (line 25)
+* EDOM, implicit usage: Library Calls. (line 81)
+* EH_FRAME_IN_DATA_SECTION: Exception Region Output.
+ (line 19)
+* EH_FRAME_SECTION_NAME: Exception Region Output.
+ (line 9)
+* eh_return instruction pattern: Standard Names. (line 832)
+* EH_RETURN_DATA_REGNO: Exception Handling. (line 6)
+* EH_RETURN_HANDLER_RTX: Exception Handling. (line 34)
+* EH_RETURN_STACKADJ_RTX: Exception Handling. (line 21)
+* EH_USES: Function Entry. (line 165)
+* ELIGIBLE_FOR_EPILOGUE_DELAY: Function Entry. (line 176)
+* ELIMINABLE_REGS: Elimination. (line 43)
+* ELSE_CLAUSE: Function Bodies. (line 6)
+* EMIT_MODE_SET: Mode Switching. (line 62)
+* EMPTY_CLASS_EXPR: Function Bodies. (line 6)
+* EMPTY_FIELD_BOUNDARY: Storage Layout. (line 231)
+* ENCODE_SECTION_INFO: Sections. (line 137)
+* ENCODE_SECTION_INFO and address validation: Addressing Modes.
+ (line 89)
+* ENCODE_SECTION_INFO usage: Instruction Output. (line 105)
+* ENDFILE_SPEC: Driver. (line 183)
+* endianness: Portability. (line 20)
+* enum machine_mode: Machine Modes. (line 6)
+* enum reg_class: Register Classes. (line 64)
+* ENUMERAL_TYPE: Types. (line 6)
+* epilogue: Function Entry. (line 6)
+* epilogue instruction pattern: Standard Names. (line 865)
+* EPILOGUE_USES: Function Entry. (line 159)
+* eq: Comparisons. (line 49)
+* eq and attributes: Expressions. (line 64)
+* eq_attr: Expressions. (line 85)
+* EQ_EXPR: Expression trees. (line 6)
+* equal: Comparisons. (line 49)
+* errno, implicit usage: Library Calls. (line 93)
+* escape sequences: Escape Sequences. (line 6)
+* exception handling: Exception Handling. (line 6)
+* exception_receiver instruction pattern: Standard Names. (line 796)
+* exclamation point: Multi-Alternative. (line 47)
+* exclusive-or, bitwise: Arithmetic. (line 142)
+* EXIT_BODY: Misc. (line 420)
+* EXIT_EXPR: Expression trees. (line 6)
+* EXIT_IGNORE_STACK: Function Entry. (line 148)
+* EXPAND_BUILTIN_SAVEREGS: Varargs. (line 91)
+* expander definitions: Expander Definitions.
+ (line 6)
+* expr_list: Insns. (line 525)
+* EXPR_STMT: Function Bodies. (line 6)
+* EXPR_STMT_EXPR: Function Bodies. (line 6)
+* expression: Expression trees. (line 6)
+* expression codes: RTL Objects. (line 47)
+* extendMN2 instruction pattern: Standard Names. (line 365)
+* extensible constraints: Simple Constraints. (line 161)
+* extern int target_flags: Run-time Target. (line 28)
+* EXTRA_CC_MODES: Condition Code. (line 67)
+* EXTRA_CONSTRAINT: Register Classes. (line 402)
+* EXTRA_SECTION_FUNCTIONS: Sections. (line 88)
+* EXTRA_SECTIONS: Sections. (line 83)
+* EXTRA_SPECS: Driver. (line 199)
+* extv instruction pattern: Standard Names. (line 374)
+* extzv instruction pattern: Standard Names. (line 388)
+* F in constraint: Simple Constraints. (line 82)
+* FAIL: Expander Definitions.
+ (line 80)
+* FATAL_EXIT_CODE: Host Config. (line 18)
+* FDL, GNU Free Documentation License: GNU Free Documentation License.
+ (line 6)
+* features, optional, in system conventions: Run-time Target. (line 31)
+* ffs: Arithmetic. (line 172)
+* ffsM2 instruction pattern: Standard Names. (line 240)
+* FIELD_DECL: Declarations. (line 6)
+* FILE_STMT: Function Bodies. (line 6)
+* FILE_STMT_FILENAME: Function Bodies. (line 6)
+* files and passes of the compiler: Passes. (line 6)
+* final pass: Passes. (line 406)
+* FINAL_PRESCAN_INSN: Instruction Output. (line 45)
+* FINAL_PRESCAN_LABEL: Instruction Output. (line 67)
+* FINAL_REG_PARM_STACK_SPACE: Stack Arguments. (line 64)
+* final_scan_insn: Function Entry. (line 189)
+* final_sequence: Instruction Output. (line 122)
+* FINALIZE_PIC: PIC. (line 30)
+* FIND_BASE_TERM: Addressing Modes. (line 137)
+* FINI_SECTION_ASM_OP: Sections. (line 60)
+* FIRST_INSN_ADDRESS: Insn Lengths. (line 35)
+* FIRST_PARM_OFFSET: Frame Layout. (line 56)
+* FIRST_PARM_OFFSET and virtual registers: Regs and Memory. (line 65)
+* FIRST_PSEUDO_REGISTER: Register Basics. (line 8)
+* FIRST_STACK_REG: Stack Registers. (line 17)
+* FIRST_VIRTUAL_REGISTER: Regs and Memory. (line 51)
+* fix: Conversions. (line 67)
+* FIX_TRUNC_EXPR: Expression trees. (line 6)
+* fix_truncMN2 instruction pattern: Standard Names. (line 352)
+* fixed register: Register Basics. (line 15)
+* FIXED_REGISTERS: Register Basics. (line 15)
+* fixed_regs: Register Basics. (line 59)
+* fixMN2 instruction pattern: Standard Names. (line 335)
+* FIXUNS_TRUNC_LIKE_FIX_TRUNC: Misc. (line 100)
+* fixuns_truncMN2 instruction pattern: Standard Names. (line 356)
+* fixunsMN2 instruction pattern: Standard Names. (line 341)
+* flags in RTL expression: Flags. (line 6)
+* float: Conversions. (line 59)
+* FLOAT_EXPR: Expression trees. (line 6)
+* float_extend: Conversions. (line 34)
+* FLOAT_LIB_COMPARE_RETURNS_BOOL (MODE, COMPARISON): Library Calls.
+ (line 73)
+* FLOAT_STORE_FLAG_VALUE: Misc. (line 240)
+* float_truncate: Conversions. (line 54)
+* FLOAT_TYPE_SIZE: Type Layout. (line 62)
+* FLOAT_WORDS_BIG_ENDIAN: Storage Layout. (line 42)
+* FLOAT_WORDS_BIG_ENDIAN, (lack of) effect on subreg: Regs and Memory.
+ (line 140)
+* floating point and cross compilation: Cross-compilation. (line 6)
+* Floating Point Emulation: Target Fragment. (line 15)
+* floatMN2 instruction pattern: Standard Names. (line 327)
+* floatunsMN2 instruction pattern: Standard Names. (line 331)
+* FOR_BODY: Function Bodies. (line 6)
+* FOR_COND: Function Bodies. (line 6)
+* FOR_EXPR: Function Bodies. (line 6)
+* FOR_INIT_STMT: Function Bodies. (line 6)
+* FOR_STMT: Function Bodies. (line 6)
+* FORCE_CODE_SECTION_ALIGN: Sections. (line 77)
+* FORCE_PREFERRED_STACK_BOUNDARY_IN_MAIN: Storage Layout. (line 149)
+* force_reg: Standard Names. (line 36)
+* frame layout: Frame Layout. (line 6)
+* FRAME_GROWS_DOWNWARD: Frame Layout. (line 30)
+* FRAME_GROWS_DOWNWARD and virtual registers: Regs and Memory.
+ (line 69)
+* frame_pointer_needed: Function Entry. (line 34)
+* FRAME_POINTER_REGNUM: Frame Registers. (line 13)
+* FRAME_POINTER_REGNUM and virtual registers: Regs and Memory.
+ (line 74)
+* FRAME_POINTER_REQUIRED: Elimination. (line 8)
+* frame_pointer_rtx: Frame Registers. (line 85)
+* frame_related: Flags. (line 222)
+* frame_related, in insn: Flags. (line 128)
+* frame_related, in mem: Flags. (line 91)
+* frame_related, in reg: Flags. (line 115)
+* frame_related, in symbol_ref: Flags. (line 180)
+* free_machine_status: Per-Function Data. (line 55)
+* ftruncM2 instruction pattern: Standard Names. (line 347)
+* function: Functions. (line 6)
+* function body: Function Bodies. (line 6)
+* function call conventions: Interface. (line 6)
+* function entry and exit: Function Entry. (line 6)
+* function units, for scheduling: Function Units. (line 6)
+* function-call insns: Calls. (line 6)
+* FUNCTION_ARG: Register Arguments. (line 10)
+* FUNCTION_ARG_ADVANCE: Register Arguments. (line 178)
+* FUNCTION_ARG_BOUNDARY: Register Arguments. (line 214)
+* FUNCTION_ARG_CALLEE_COPIES: Register Arguments. (line 112)
+* FUNCTION_ARG_PADDING: Register Arguments. (line 189)
+* FUNCTION_ARG_PARTIAL_NREGS: Register Arguments. (line 80)
+* FUNCTION_ARG_PASS_BY_REFERENCE: Register Arguments. (line 99)
+* FUNCTION_ARG_REG_LITTLE_ENDIAN: Register Arguments. (line 123)
+* FUNCTION_ARG_REGNO_P: Register Arguments. (line 219)
+* FUNCTION_BOUNDARY: Storage Layout. (line 159)
+* FUNCTION_DECL: Functions. (line 6)
+* FUNCTION_INCOMING_ARG: Register Arguments. (line 66)
+* FUNCTION_MODE: Misc. (line 259)
+* FUNCTION_OK_FOR_SIBCALL: Tail Calls. (line 6)
+* FUNCTION_OUTGOING_VALUE: Scalar Return. (line 39)
+* FUNCTION_PROFILER: Profiling. (line 8)
+* FUNCTION_TYPE: Types. (line 6)
+* FUNCTION_VALUE: Scalar Return. (line 13)
+* FUNCTION_VALUE_REGNO_P: Scalar Return. (line 73)
+* functions, leaf: Leaf Functions. (line 6)
+* fundamental type: Types. (line 6)
+* g in constraint: Simple Constraints. (line 108)
+* G in constraint: Simple Constraints. (line 86)
+* GCC and portability: Portability. (line 6)
+* GCC_DRIVER_HOST_INITIALIZATION: Host Config. (line 91)
+* GCOV_TYPE_SIZE: Type Layout. (line 151)
+* ge: Comparisons. (line 69)
+* ge and attributes: Expressions. (line 64)
+* GE_EXPR: Expression trees. (line 6)
+* GEN_ERRNO_RTX: Library Calls. (line 93)
+* gencodes: Passes. (line 111)
+* genconfig: Passes. (line 442)
+* general_operand: RTL Template. (line 57)
+* GENERAL_REGS: Register Classes. (line 23)
+* generating assembler output: Output Statement. (line 6)
+* generating insns: RTL Template. (line 6)
+* genflags: Passes. (line 111)
+* get_attr: Expressions. (line 80)
+* get_attr_length: Insn Lengths. (line 51)
+* GET_CLASS_NARROWEST_MODE: Machine Modes. (line 220)
+* GET_CODE: RTL Objects. (line 47)
+* get_frame_size: Elimination. (line 31)
+* get_insns: Insns. (line 34)
+* get_last_insn: Insns. (line 34)
+* GET_MODE: Machine Modes. (line 175)
+* GET_MODE_ALIGNMENT: Machine Modes. (line 207)
+* GET_MODE_BITSIZE: Machine Modes. (line 199)
+* GET_MODE_CLASS: Machine Modes. (line 189)
+* GET_MODE_MASK: Machine Modes. (line 202)
+* GET_MODE_NAME: Machine Modes. (line 186)
+* GET_MODE_NUNITS: Machine Modes. (line 216)
+* GET_MODE_SIZE: Machine Modes. (line 196)
+* GET_MODE_UNIT_SIZE: Machine Modes. (line 210)
+* GET_MODE_WIDER_MODE: Machine Modes. (line 192)
+* GET_RTX_CLASS: RTL Classes. (line 6)
+* GET_RTX_FORMAT: RTL Classes. (line 119)
+* GET_RTX_LENGTH: RTL Classes. (line 116)
+* geu: Comparisons. (line 69)
+* geu and attributes: Expressions. (line 64)
+* global common subexpression elimination: Passes. (line 220)
+* global register allocation: Passes. (line 338)
+* GLOBAL_INIT_PRIORITY: Function Basics. (line 6)
+* GO_IF_LEGITIMATE_ADDRESS: Addressing Modes. (line 45)
+* GO_IF_MODE_DEPENDENT_ADDRESS: Addressing Modes. (line 214)
+* GOTO_DESTINATION: Function Bodies. (line 6)
+* GOTO_FAKE_P: Function Bodies. (line 6)
+* GOTO_STMT: Function Bodies. (line 6)
+* greater than: Comparisons. (line 57)
+* gt: Comparisons. (line 57)
+* gt and attributes: Expressions. (line 64)
+* GT_EXPR: Expression trees. (line 6)
+* gtu: Comparisons. (line 61)
+* gtu and attributes: Expressions. (line 64)
+* H in constraint: Simple Constraints. (line 86)
+* HANDLE_PRAGMA: Misc. (line 294)
+* HANDLE_PRAGMA_PACK_PUSH_POP: Misc. (line 366)
+* HANDLE_SYSV_PRAGMA: Misc. (line 352)
+* HANDLER: Function Bodies. (line 6)
+* HANDLER_BODY: Function Bodies. (line 6)
+* HANDLER_PARMS: Function Bodies. (line 6)
+* hard registers: Regs and Memory. (line 9)
+* HARD_FRAME_POINTER_REGNUM: Frame Registers. (line 19)
+* HARD_REGNO_CALL_PART_CLOBBERED: Register Basics. (line 52)
+* HARD_REGNO_CALLER_SAVE_MODE: Caller Saves. (line 27)
+* HARD_REGNO_MODE_OK: Values in Registers. (line 22)
+* HARD_REGNO_NREGS: Values in Registers. (line 10)
+* HAS_INIT_SECTION: Macros for Initialization.
+ (line 19)
+* HAVE_DOS_BASED_FILE_SYSTEM: Host Config. (line 44)
+* HAVE_POST_DECREMENT: Addressing Modes. (line 8)
+* HAVE_POST_INCREMENT: Addressing Modes. (line 8)
+* HAVE_POST_MODIFY_DISP: Addressing Modes. (line 16)
+* HAVE_POST_MODIFY_REG: Addressing Modes. (line 22)
+* HAVE_PRE_DECREMENT: Addressing Modes. (line 8)
+* HAVE_PRE_INCREMENT: Addressing Modes. (line 8)
+* HAVE_PRE_MODIFY_DISP: Addressing Modes. (line 16)
+* HAVE_PRE_MODIFY_REG: Addressing Modes. (line 22)
+* HCmode: Machine Modes. (line 111)
+* HFmode: Machine Modes. (line 58)
+* high: Constants. (line 114)
+* HImode: Machine Modes. (line 29)
+* HImode, in insn: Insns. (line 225)
+* host makefile fragment: Host Fragment. (line 6)
+* HOST_BIT_BUCKET: Host Config. (line 79)
+* HOST_EXECUTABLE_SUFFIX: Host Config. (line 73)
+* HOST_OBJECT_SUFFIX: Host Config. (line 68)
+* I in constraint: Simple Constraints. (line 69)
+* i in constraint: Simple Constraints. (line 58)
+* IBM_FLOAT_FORMAT: Storage Layout. (line 407)
+* identifier: Identifiers. (line 6)
+* IDENTIFIER_LENGTH: Identifiers. (line 20)
+* IDENTIFIER_NODE: Identifiers. (line 6)
+* IDENTIFIER_OPNAME_P: Identifiers. (line 25)
+* IDENTIFIER_POINTER: Identifiers. (line 15)
+* IDENTIFIER_TYPENAME_P: Identifiers. (line 31)
+* IEEE_FLOAT_FORMAT: Storage Layout. (line 400)
+* if conversion: Passes. (line 290)
+* IF_COND: Function Bodies. (line 6)
+* IF_STMT: Function Bodies. (line 6)
+* if_then_else: Comparisons. (line 77)
+* if_then_else and attributes: Expressions. (line 32)
+* if_then_else usage: Side Effects. (line 51)
+* IFCVT_MODIFY_CANCEL: Misc. (line 517)
+* IFCVT_MODIFY_FINAL: Misc. (line 512)
+* IFCVT_MODIFY_INSN: Misc. (line 508)
+* IFCVT_MODIFY_TESTS: Misc. (line 501)
+* IMAGPART_EXPR: Expression trees. (line 6)
+* immediate_operand: RTL Template. (line 72)
+* IMMEDIATE_PREFIX: Instruction Output. (line 129)
+* in_data: Sections. (line 83)
+* in_struct: Flags. (line 237)
+* in_struct, in code_label: Flags. (line 53)
+* in_struct, in insn: Flags. (line 30)
+* in_struct, in label_ref: Flags. (line 48)
+* in_struct, in mem: Flags. (line 76)
+* in_struct, in reg: Flags. (line 110)
+* in_struct, in subreg: Flags. (line 191)
+* in_text: Sections. (line 83)
+* include: Including Patterns. (line 6)
+* INCLUDE_DEFAULTS: Driver. (line 383)
+* inclusive-or, bitwise: Arithmetic. (line 137)
+* INCOMING_FRAME_SP_OFFSET: Frame Layout. (line 125)
+* INCOMING_REGNO: Register Basics. (line 96)
+* INCOMING_RETURN_ADDR_RTX: Frame Layout. (line 112)
+* INDEX_REG_CLASS: Register Classes. (line 117)
+* indirect_jump instruction pattern: Standard Names. (line 575)
+* INDIRECT_REF: Expression trees. (line 6)
+* INIT_CUMULATIVE_ARGS: Register Arguments. (line 144)
+* INIT_CUMULATIVE_INCOMING_ARGS: Register Arguments. (line 169)
+* INIT_CUMULATIVE_LIBCALL_ARGS: Register Arguments. (line 163)
+* INIT_ENVIRONMENT: Driver. (line 322)
+* INIT_EXPANDERS: Per-Function Data. (line 41)
+* INIT_EXPR: Expression trees. (line 6)
+* init_machine_status: Per-Function Data. (line 47)
+* INIT_SECTION_ASM_OP <1>: Macros for Initialization.
+ (line 9)
+* INIT_SECTION_ASM_OP: Sections. (line 54)
+* INIT_TARGET_OPTABS: Library Calls. (line 68)
+* INITIAL_ELIMINATION_OFFSET: Elimination. (line 78)
+* INITIAL_FRAME_POINTER_OFFSET: Elimination. (line 31)
+* initialization routines: Initialization. (line 6)
+* INITIALIZE_TRAMPOLINE: Trampolines. (line 55)
+* inline on rtx, automatic: Passes. (line 120)
+* inline on trees, automatic: Passes. (line 80)
+* inlining: Target Attributes. (line 69)
+* insn: Insns. (line 64)
+* insn and /f: Flags. (line 128)
+* insn and /i: Flags. (line 154)
+* insn and /j: Flags. (line 172)
+* insn and /s: Flags. (line 30)
+* insn and /u: Flags. (line 24)
+* insn and /v: Flags. (line 34)
+* insn attributes: Insn Attributes. (line 6)
+* insn canonicalization: Insn Canonicalizations.
+ (line 6)
+* insn includes: Including Patterns. (line 6)
+* insn lengths, computing: Insn Lengths. (line 6)
+* insn splitting: Insn Splitting. (line 6)
+* insn-attr.h: Defining Attributes. (line 24)
+* INSN_ANNULLED_BRANCH_P: Flags. (line 24)
+* INSN_CACHE_DEPTH: Trampolines. (line 116)
+* INSN_CACHE_LINE_WIDTH: Trampolines. (line 109)
+* INSN_CACHE_SIZE: Trampolines. (line 106)
+* INSN_CODE: Insns. (line 251)
+* INSN_DEAD_CODE_P: Flags. (line 30)
+* INSN_DELETED_P: Flags. (line 34)
+* INSN_FROM_TARGET_P: Flags. (line 38)
+* insn_list: Insns. (line 525)
+* insn_list and /c: Flags. (line 64)
+* insn_list and /j: Flags. (line 70)
+* INSN_REFERENCES_ARE_DELAYED: Misc. (line 436)
+* INSN_SETS_ARE_DELAYED: Misc. (line 425)
+* INSN_UID: Insns. (line 23)
+* insns: Insns. (line 6)
+* insns, generating: RTL Template. (line 6)
+* insns, recognizing: RTL Template. (line 6)
+* instruction attributes: Insn Attributes. (line 6)
+* instruction combination: Passes. (line 279)
+* instruction patterns: Patterns. (line 6)
+* instruction recognizer: Passes. (line 447)
+* instruction scheduling: Passes. (line 309)
+* instruction splitting: Insn Splitting. (line 6)
+* insv instruction pattern: Standard Names. (line 391)
+* INT_TYPE_SIZE: Type Layout. (line 11)
+* INTEGER_CST: Expression trees. (line 6)
+* INTEGER_TYPE: Types. (line 6)
+* INTEGRATE_THRESHOLD: Misc. (line 264)
+* integrated: Flags. (line 272)
+* integrated, in insn: Flags. (line 154)
+* integrated, in reg: Flags. (line 105)
+* integrated, in symbol_ref: Flags. (line 210)
+* INTEL_EXTENDED_IEEE_FORMAT: Type Layout. (line 82)
+* Interdependence of Patterns: Dependent Patterns. (line 6)
+* interfacing to GCC output: Interface. (line 6)
+* INTMAX_TYPE: Type Layout. (line 167)
+* introduction: Top. (line 6)
+* INVOKE__main: Macros for Initialization.
+ (line 51)
+* ior: Arithmetic. (line 137)
+* ior and attributes: Expressions. (line 50)
+* ior, canonicalization of: Insn Canonicalizations.
+ (line 42)
+* iorM3 instruction pattern: Standard Names. (line 167)
+* IS_ASM_LOGICAL_LINE_SEPARATOR: Data Output. (line 124)
+* isinf: Cross-compilation. (line 83)
+* isnan: Cross-compilation. (line 88)
+* jump: Flags. (line 285)
+* jump instruction pattern: Standard Names. (line 466)
+* jump instruction patterns: Jump Patterns. (line 6)
+* jump instructions and set: Side Effects. (line 51)
+* jump optimization: Passes. (line 146)
+* jump threading: Passes. (line 172)
+* jump, in call_insn: Flags. (line 176)
+* jump, in insn: Flags. (line 172)
+* jump, in insn_list: Flags. (line 70)
+* jump, in mem: Flags. (line 85)
+* JUMP_ALIGN: Alignment Output. (line 8)
+* jump_insn: Insns. (line 74)
+* JUMP_LABEL: Insns. (line 80)
+* JUMP_TABLES_IN_TEXT_SECTION: Sections. (line 128)
+* LABEL_ALIGN: Alignment Output. (line 51)
+* LABEL_ALIGN_AFTER_BARRIER: Alignment Output. (line 21)
+* LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP: Alignment Output. (line 29)
+* LABEL_ALIGN_MAX_SKIP: Alignment Output. (line 61)
+* LABEL_ALTERNATE_NAME: Insns. (line 146)
+* LABEL_DECL: Declarations. (line 6)
+* LABEL_NUSES: Insns. (line 142)
+* LABEL_OUTSIDE_LOOP_P: Flags. (line 48)
+* LABEL_PRESERVE_P: Flags. (line 53)
+* label_ref: Constants. (line 94)
+* label_ref and /s: Flags. (line 48)
+* label_ref and /v: Flags. (line 59)
+* label_ref, RTL sharing: Sharing. (line 35)
+* LABEL_REF_NONLOCAL_P: Flags. (line 59)
+* LABEL_STMT: Function Bodies. (line 6)
+* LABEL_STMT_LABEL: Function Bodies. (line 6)
+* large return values: Aggregate Return. (line 6)
+* LAST_STACK_REG: Stack Registers. (line 21)
+* LAST_VIRTUAL_REGISTER: Regs and Memory. (line 51)
+* LD_FINI_SWITCH: Macros for Initialization.
+ (line 29)
+* LD_INIT_SWITCH: Macros for Initialization.
+ (line 25)
+* LDD_SUFFIX: Macros for Initialization.
+ (line 120)
+* ldexp: Cross-compilation. (line 45)
+* le: Comparisons. (line 73)
+* le and attributes: Expressions. (line 64)
+* LE_EXPR: Expression trees. (line 6)
+* leaf functions: Leaf Functions. (line 6)
+* leaf_function_p: Standard Names. (line 537)
+* LEAF_REG_REMAP: Leaf Functions. (line 38)
+* LEAF_REGISTERS: Leaf Functions. (line 24)
+* left rotate: Arithmetic. (line 160)
+* left shift: Arithmetic. (line 147)
+* LEGITIMATE_CONSTANT_P: Addressing Modes. (line 229)
+* LEGITIMATE_PIC_OPERAND_P: PIC. (line 46)
+* LEGITIMIZE_ADDRESS: Addressing Modes. (line 147)
+* LEGITIMIZE_RELOAD_ADDRESS: Addressing Modes. (line 169)
+* less than: Comparisons. (line 65)
+* less than or equal: Comparisons. (line 73)
+* leu: Comparisons. (line 73)
+* leu and attributes: Expressions. (line 64)
+* LIB2FUNCS_EXTRA: Target Fragment. (line 11)
+* LIB_SPEC: Driver. (line 158)
+* LIBCALL_VALUE: Scalar Return. (line 56)
+* libgcc.a: Library Calls. (line 6)
+* LIBGCC2_CFLAGS: Target Fragment. (line 8)
+* LIBGCC2_WORDS_BIG_ENDIAN: Storage Layout. (line 35)
+* LIBGCC_NEEDS_DOUBLE: Library Calls. (line 104)
+* LIBGCC_SPEC: Driver. (line 166)
+* library subroutine names: Library Calls. (line 6)
+* LIBRARY_PATH_ENV: Misc. (line 481)
+* LIMIT_RELOAD_CLASS: Register Classes. (line 185)
+* LINK_COMMAND_SPEC: Driver. (line 262)
+* LINK_COST_FREE: Flags. (line 64)
+* LINK_COST_ZERO: Flags. (line 70)
+* LINK_ELIMINATE_DUPLICATE_LDIRECTORIES: Driver. (line 272)
+* LINK_GCC_C_SEQUENCE_SPEC: Driver. (line 258)
+* LINK_LIBGCC_SPECIAL: Driver. (line 244)
+* LINK_LIBGCC_SPECIAL_1: Driver. (line 251)
+* LINK_SPEC: Driver. (line 151)
+* linkage: Function Basics. (line 6)
+* LINKER_DOES_NOT_WORK_WITH_DWARF2: SDB and DWARF. (line 32)
+* list: Containers. (line 6)
+* lo_sum: Arithmetic. (line 18)
+* load address instruction: Simple Constraints. (line 152)
+* LOAD_ARGS_REVERSED: Register Arguments. (line 227)
+* LOAD_EXTEND_OP: Misc. (line 82)
+* load_multiple instruction pattern: Standard Names. (line 125)
+* local register allocation: Passes. (line 329)
+* LOCAL_ALIGNMENT: Storage Layout. (line 220)
+* LOCAL_CLASS_P: Classes. (line 66)
+* LOCAL_INCLUDE_DIR: Driver. (line 329)
+* LOCAL_LABEL_PREFIX: Instruction Output. (line 129)
+* LOCAL_REGNO: Register Basics. (line 110)
+* LOG_LINKS: Insns. (line 270)
+* logical-and, bitwise: Arithmetic. (line 132)
+* LONG_DOUBLE_TYPE_SIZE: Type Layout. (line 71)
+* LONG_LONG_TYPE_SIZE: Type Layout. (line 39)
+* LONG_TYPE_SIZE: Type Layout. (line 21)
+* longjmp and automatic variables: Interface. (line 53)
+* loop optimization: Passes. (line 243)
+* LOOP_ALIGN: Alignment Output. (line 34)
+* LOOP_ALIGN_MAX_SKIP: Alignment Output. (line 47)
+* LOOP_EXPR: Expression trees. (line 6)
+* looping instruction patterns: Looping Patterns. (line 6)
+* LSHIFT_EXPR: Expression trees. (line 6)
+* lshiftrt: Arithmetic. (line 155)
+* lshiftrt and attributes: Expressions. (line 64)
+* lshrM3 instruction pattern: Standard Names. (line 224)
+* lt: Comparisons. (line 65)
+* lt and attributes: Expressions. (line 64)
+* LT_EXPR: Expression trees. (line 6)
+* ltu: Comparisons. (line 65)
+* m in constraint: Simple Constraints. (line 17)
+* machine attributes: Target Attributes. (line 6)
+* machine description macros: Target Macros. (line 6)
+* machine descriptions: Machine Desc. (line 6)
+* machine mode conversions: Conversions. (line 6)
+* machine modes: Machine Modes. (line 6)
+* machine specific constraints: Machine Constraints. (line 6)
+* MACHINE_DEPENDENT_REORG: Misc. (line 449)
+* macros, target description: Target Macros. (line 6)
+* MAKE_DECL_ONE_ONLY (DECL): Label Output. (line 104)
+* make_safe_from: Expander Definitions.
+ (line 148)
+* makefile fragment: Fragments. (line 6)
+* makefile targets: Makefile. (line 6)
+* mark_machine_status: Per-Function Data. (line 62)
+* MASK_RETURN_ADDR: Exception Region Output.
+ (line 28)
+* match_dup <1>: define_peephole2. (line 28)
+* match_dup: RTL Template. (line 94)
+* match_dup and attributes: Insn Lengths. (line 16)
+* match_insn: RTL Template. (line 244)
+* match_insn2: RTL Template. (line 253)
+* match_op_dup: RTL Template. (line 184)
+* match_operand: RTL Template. (line 16)
+* match_operand and attributes: Expressions. (line 55)
+* match_operator: RTL Template. (line 116)
+* match_par_dup: RTL Template. (line 240)
+* match_parallel: RTL Template. (line 193)
+* match_scratch <1>: define_peephole2. (line 28)
+* match_scratch: RTL Template. (line 79)
+* matching constraint: Simple Constraints. (line 130)
+* matching operands: Output Template. (line 50)
+* math libraries: Interface. (line 72)
+* math, in RTL: Arithmetic. (line 6)
+* MATH_LIBRARY: Misc. (line 474)
+* MAX_BITS_PER_WORD: Storage Layout. (line 58)
+* MAX_CHAR_TYPE_SIZE: Type Layout. (line 50)
+* MAX_CONDITIONAL_EXECUTE: Misc. (line 495)
+* MAX_FIXED_MODE_SIZE: Storage Layout. (line 349)
+* MAX_INTEGER_COMPUTATION_MODE: Misc. (line 466)
+* MAX_LONG_DOUBLE_TYPE_SIZE: Type Layout. (line 76)
+* MAX_LONG_TYPE_SIZE: Type Layout. (line 32)
+* MAX_MOVE_MAX: Misc. (line 110)
+* MAX_OFILE_ALIGNMENT: Storage Layout. (line 188)
+* MAX_REGS_PER_ADDRESS: Addressing Modes. (line 39)
+* MAX_WCHAR_TYPE_SIZE: Type Layout. (line 144)
+* maxM3 instruction pattern: Standard Names. (line 171)
+* MAYBE_REG_PARM_STACK_SPACE: Stack Arguments. (line 64)
+* mcount: Profiling. (line 12)
+* MD_ASM_CLOBBERS: Misc. (line 462)
+* MD_CAN_REDIRECT_BRANCH: Misc. (line 548)
+* MD_EXEC_PREFIX: Driver. (line 299)
+* MD_FALLBACK_FRAME_STATE_FOR: Exception Handling. (line 81)
+* MD_STARTFILE_PREFIX: Driver. (line 311)
+* MD_STARTFILE_PREFIX_1: Driver. (line 317)
+* mem: Regs and Memory. (line 249)
+* mem and /f: Flags. (line 91)
+* mem and /j: Flags. (line 85)
+* mem and /s: Flags. (line 76)
+* mem and /u: Flags. (line 159)
+* mem and /v: Flags. (line 100)
+* mem, RTL sharing: Sharing. (line 40)
+* MEM_IN_STRUCT_P: Flags. (line 76)
+* MEM_KEEP_ALIAS_SET_P: Flags. (line 85)
+* MEM_SCALAR_P: Flags. (line 91)
+* MEM_VOLATILE_P: Flags. (line 100)
+* MEMBER_TYPE_FORCES_BLK: Storage Layout. (line 319)
+* memcpy, implicit usage: Library Calls. (line 99)
+* memmove, implicit usage: Library Calls. (line 99)
+* memory reference, nonoffsettable: Simple Constraints. (line 251)
+* memory references in constraints: Simple Constraints. (line 17)
+* MEMORY_MOVE_COST: Costs. (line 109)
+* memset, implicit usage: Library Calls. (line 99)
+* METHOD_TYPE: Types. (line 6)
+* MIN_UNITS_PER_WORD: Storage Layout. (line 67)
+* MINIMUM_ATOMIC_ALIGNMENT: Storage Layout. (line 166)
+* minM3 instruction pattern: Standard Names. (line 171)
+* minus: Arithmetic. (line 27)
+* minus and attributes: Expressions. (line 64)
+* minus, canonicalization of: Insn Canonicalizations.
+ (line 21)
+* MINUS_EXPR: Expression trees. (line 6)
+* mod: Arithmetic. (line 113)
+* mod and attributes: Expressions. (line 64)
+* MODDI3_LIBCALL: Library Calls. (line 56)
+* mode classes: Machine Modes. (line 134)
+* mode switching: Mode Switching. (line 6)
+* MODE_BASE_REG_CLASS: Register Classes. (line 111)
+* MODE_CC: Machine Modes. (line 163)
+* MODE_COMPLEX_FLOAT: Machine Modes. (line 155)
+* MODE_COMPLEX_INT: Machine Modes. (line 152)
+* MODE_FLOAT: Machine Modes. (line 148)
+* MODE_FUNCTION: Machine Modes. (line 159)
+* MODE_INT: Machine Modes. (line 140)
+* MODE_NEEDED: Mode Switching. (line 41)
+* MODE_PARTIAL_INT: Machine Modes. (line 144)
+* MODE_PRIORITY_TO_MODE: Mode Switching. (line 54)
+* MODE_RANDOM: Machine Modes. (line 168)
+* MODES_TIEABLE_P: Values in Registers. (line 83)
+* modifiers in constraints: Modifiers. (line 6)
+* MODIFY_EXPR: Expression trees. (line 6)
+* MODIFY_TARGET_NAME: Driver. (line 338)
+* modM3 instruction pattern: Standard Names. (line 167)
+* MODSI3_LIBCALL: Library Calls. (line 26)
+* MOVE_BY_PIECES_P: Costs. (line 189)
+* MOVE_MAX: Misc. (line 105)
+* MOVE_MAX_PIECES: Costs. (line 195)
+* MOVE_RATIO: Costs. (line 176)
+* movM instruction pattern: Standard Names. (line 11)
+* movMODEcc instruction pattern: Standard Names. (line 401)
+* movstrictM instruction pattern: Standard Names. (line 119)
+* movstrM instruction pattern: Standard Names. (line 271)
+* MULDI3_LIBCALL: Library Calls. (line 38)
+* mulhisi3 instruction pattern: Standard Names. (line 178)
+* mulM3 instruction pattern: Standard Names. (line 167)
+* mulqihi3 instruction pattern: Standard Names. (line 182)
+* MULSI3_LIBCALL: Library Calls. (line 8)
+* mulsidi3 instruction pattern: Standard Names. (line 182)
+* mult: Arithmetic. (line 84)
+* mult and attributes: Expressions. (line 64)
+* mult, canonicalization of: Insn Canonicalizations.
+ (line 21)
+* MULT_EXPR: Expression trees. (line 6)
+* MULTILIB_DEFAULTS: Driver. (line 278)
+* MULTILIB_DIRNAMES: Target Fragment. (line 64)
+* MULTILIB_EXCEPTIONS: Target Fragment. (line 84)
+* MULTILIB_EXTRA_OPTS: Target Fragment. (line 96)
+* MULTILIB_MATCHES: Target Fragment. (line 77)
+* MULTILIB_OPTIONS: Target Fragment. (line 44)
+* multiple alternative constraints: Multi-Alternative. (line 6)
+* MULTIPLE_SYMBOL_SPACES: Misc. (line 455)
+* multiplication: Arithmetic. (line 84)
+* MUST_PASS_IN_STACK: Register Arguments. (line 60)
+* MUST_PASS_IN_STACK, and FUNCTION_ARG: Register Arguments. (line 52)
+* n in constraint: Simple Constraints. (line 63)
+* N_REG_CLASSES: Register Classes. (line 75)
+* name: Identifiers. (line 6)
+* named patterns and conditions: Patterns. (line 48)
+* names, pattern: Standard Names. (line 6)
+* namespace: Namespaces. (line 6)
+* namespace, class, scope: Scopes. (line 6)
+* NAMESPACE_DECL <1>: Declarations. (line 6)
+* NAMESPACE_DECL: Namespaces. (line 6)
+* ne: Comparisons. (line 53)
+* ne and attributes: Expressions. (line 64)
+* NE_EXPR: Expression trees. (line 6)
+* NEED_ATEXIT: Misc. (line 406)
+* neg: Arithmetic. (line 80)
+* neg and attributes: Expressions. (line 64)
+* neg, canonicalization of: Insn Canonicalizations.
+ (line 21)
+* NEGATE_EXPR: Expression trees. (line 6)
+* negM2 instruction pattern: Standard Names. (line 228)
+* nested functions, trampolines for: Trampolines. (line 6)
+* next_cc0_user: Jump Patterns. (line 64)
+* NEXT_INSN: Insns. (line 30)
+* NEXT_OBJC_RUNTIME: Library Calls. (line 112)
+* nil: RTL Objects. (line 73)
+* NO_BUILTIN_PTRDIFF_TYPE: Driver. (line 91)
+* NO_BUILTIN_SIZE_TYPE: Driver. (line 82)
+* NO_BUILTIN_WCHAR_TYPE: Driver. (line 100)
+* NO_BUILTIN_WINT_TYPE: Driver. (line 109)
+* NO_DBX_FUNCTION_END: DBX Hooks. (line 85)
+* NO_DOLLAR_IN_LABEL: Misc. (line 384)
+* NO_DOT_IN_LABEL: Misc. (line 390)
+* NO_FUNCTION_CSE: Costs. (line 240)
+* NO_IMPLICIT_EXTERN_C: Misc. (line 288)
+* no_new_pseudos: Standard Names. (line 77)
+* NO_PROFILE_COUNTERS: Profiling. (line 27)
+* NO_RECURSIVE_FUNCTION_CSE: Costs. (line 244)
+* NO_REGS: Register Classes. (line 17)
+* NON_SAVING_SETJMP: Register Basics. (line 89)
+* nonlocal_goto instruction pattern: Standard Names. (line 768)
+* nonlocal_goto_receiver instruction pattern: Standard Names. (line 785)
+* nonoffsettable memory reference: Simple Constraints. (line 251)
+* nop instruction pattern: Standard Names. (line 570)
+* NOP_EXPR: Expression trees. (line 6)
+* NORMAL_MODE: Mode Switching. (line 48)
+* not: Arithmetic. (line 128)
+* not and attributes: Expressions. (line 50)
+* not equal: Comparisons. (line 53)
+* not, canonicalization of: Insn Canonicalizations.
+ (line 21)
+* note: Insns. (line 158)
+* NOTE_INSN_BLOCK_BEG: Insns. (line 183)
+* NOTE_INSN_BLOCK_END: Insns. (line 183)
+* NOTE_INSN_DELETED: Insns. (line 173)
+* NOTE_INSN_DELETED_LABEL: Insns. (line 178)
+* NOTE_INSN_EH_REGION_BEG: Insns. (line 189)
+* NOTE_INSN_EH_REGION_END: Insns. (line 189)
+* NOTE_INSN_FUNCTION_END: Insns. (line 213)
+* NOTE_INSN_LOOP_BEG: Insns. (line 197)
+* NOTE_INSN_LOOP_CONT: Insns. (line 203)
+* NOTE_INSN_LOOP_END: Insns. (line 197)
+* NOTE_INSN_LOOP_VTOP: Insns. (line 207)
+* NOTE_INSN_SETJMP: Insns. (line 219)
+* NOTE_LINE_NUMBER: Insns. (line 158)
+* NOTE_SOURCE_FILE: Insns. (line 158)
+* NOTICE_UPDATE_CC: Condition Code. (line 32)
+* NUM_MACHINE_MODES: Machine Modes. (line 181)
+* NUM_MODES_FOR_MODE_SWITCHING: Mode Switching. (line 29)
+* o in constraint: Simple Constraints. (line 21)
+* OBJC_GEN_METHOD_LABEL: Label Output. (line 273)
+* OBJC_PROLOGUE: File Framework. (line 78)
+* OBJECT_FORMAT_COFF: Macros for Initialization.
+ (line 96)
+* OBJECT_FORMAT_ROSE: Macros for Initialization.
+ (line 102)
+* OFFSET_TYPE: Types. (line 6)
+* offsettable address: Simple Constraints. (line 21)
+* OImode: Machine Modes. (line 51)
+* ON_EXIT: Misc. (line 412)
+* one_cmplM2 instruction pattern: Standard Names. (line 250)
+* operand access: Accessors. (line 6)
+* operand constraints: Constraints. (line 6)
+* operand substitution: Output Template. (line 6)
+* operands: Patterns. (line 54)
+* OPTIMIZATION_OPTIONS: Run-time Target. (line 140)
+* OPTIMIZE_MODE_SWITCHING: Mode Switching. (line 8)
+* optional hardware or system features: Run-time Target. (line 31)
+* options, directory search: Including Patterns. (line 45)
+* order of register allocation: Allocation Order. (line 6)
+* ORDER_REGS_FOR_LOCAL_ALLOC: Allocation Order. (line 22)
+* Ordering of Patterns: Pattern Ordering. (line 6)
+* other register constraints: Simple Constraints. (line 161)
+* OUTGOING_REG_PARM_STACK_SPACE: Stack Arguments. (line 92)
+* OUTGOING_REGNO: Register Basics. (line 103)
+* output of assembler code: File Framework. (line 6)
+* output statements: Output Statement. (line 6)
+* output templates: Output Template. (line 6)
+* OUTPUT_ADDR_CONST_EXTRA: Data Output. (line 38)
+* output_asm_insn: Output Statement. (line 53)
+* OUTPUT_QUOTED_STRING: File Framework. (line 58)
+* overflow while constant folding: Cross-compilation. (line 109)
+* OVERLOAD: Functions. (line 6)
+* OVERRIDE_OPTIONS: Run-time Target. (line 130)
+* OVL_CURRENT: Functions. (line 6)
+* OVL_NEXT: Functions. (line 6)
+* p in constraint: Simple Constraints. (line 152)
+* PAD_VARARGS_DOWN: Register Arguments. (line 206)
+* parallel: Side Effects. (line 195)
+* parameters, miscellaneous: Misc. (line 6)
+* PARM_BOUNDARY: Storage Layout. (line 128)
+* PARM_DECL: Declarations. (line 6)
+* PARSE_LDD_OUTPUT: Macros for Initialization.
+ (line 125)
+* parsing pass: Passes. (line 10)
+* passes and files of the compiler: Passes. (line 6)
+* passing arguments: Interface. (line 37)
+* PATH_SEPARATOR: Host Config. (line 52)
+* PATTERN: Insns. (line 241)
+* pattern conditions: Patterns. (line 44)
+* pattern names: Standard Names. (line 6)
+* Pattern Ordering: Pattern Ordering. (line 6)
+* patterns: Patterns. (line 6)
+* pc: Regs and Memory. (line 236)
+* pc and attributes: Insn Lengths. (line 20)
+* pc, RTL sharing: Sharing. (line 25)
+* pc_rtx: Regs and Memory. (line 241)
+* PCC_BITFIELD_TYPE_MATTERS: Storage Layout. (line 251)
+* PCC_STATIC_STRUCT_RETURN: Aggregate Return. (line 70)
+* PDImode: Machine Modes. (line 40)
+* peephole optimization: Passes. (line 406)
+* peephole optimization, RTL representation: Side Effects. (line 229)
+* peephole optimizer definitions: Peephole Definitions.
+ (line 6)
+* per-function data: Per-Function Data. (line 6)
+* percent sign: Output Template. (line 6)
+* PIC: PIC. (line 6)
+* PIC_OFFSET_TABLE_REG_CALL_CLOBBERED: PIC. (line 25)
+* PIC_OFFSET_TABLE_REGNUM: PIC. (line 15)
+* plus: Arithmetic. (line 14)
+* plus and attributes: Expressions. (line 64)
+* plus, canonicalization of: Insn Canonicalizations.
+ (line 21)
+* PLUS_EXPR: Expression trees. (line 6)
+* Pmode: Misc. (line 247)
+* pointer: Types. (line 6)
+* POINTER_SIZE: Storage Layout. (line 73)
+* POINTER_TYPE: Types. (line 6)
+* POINTERS_EXTEND_UNSIGNED: Storage Layout. (line 78)
+* portability: Portability. (line 6)
+* position independent code: PIC. (line 6)
+* post_dec: Incdec. (line 25)
+* post_inc: Incdec. (line 30)
+* post_modify: Incdec. (line 33)
+* pragma: Misc. (line 298)
+* pre_dec: Incdec. (line 8)
+* PRE_GCC3_DWARF_FRAME_REGISTERS: Frame Registers. (line 109)
+* pre_inc: Incdec. (line 22)
+* predefined macros: Run-time Target. (line 6)
+* PREDICATE_CODES: Misc. (line 9)
+* predication: Conditional Execution.
+ (line 6)
+* PREFERRED_DEBUGGING_TYPE: All Debuggers. (line 41)
+* PREFERRED_OUTPUT_RELOAD_CLASS: Register Classes. (line 180)
+* PREFERRED_RELOAD_CLASS: Register Classes. (line 160)
+* PREFERRED_STACK_BOUNDARY: Storage Layout. (line 142)
+* prefetch: Side Effects. (line 303)
+* prefetch instruction pattern: Standard Names. (line 906)
+* PRETEND_OUTGOING_VARARGS_NAMED: Varargs. (line 147)
+* prev_active_insn: define_peephole. (line 60)
+* prev_cc0_setter: Jump Patterns. (line 64)
+* PREV_INSN: Insns. (line 26)
+* PRINT_OPERAND: Instruction Output. (line 72)
+* PRINT_OPERAND_ADDRESS: Instruction Output. (line 100)
+* PRINT_OPERAND_PUNCT_VALID_P: Instruction Output. (line 93)
+* probe instruction pattern: Standard Names. (line 747)
+* product: Arithmetic. (line 84)
+* PROFILE_BEFORE_PROLOGUE: Profiling. (line 34)
+* PROFILE_HOOK: Profiling. (line 22)
+* profiling, code generation: Profiling. (line 6)
+* program counter: Regs and Memory. (line 237)
+* prologue: Function Entry. (line 6)
+* prologue instruction pattern: Standard Names. (line 852)
+* PROMOTE_FOR_CALL_ONLY: Storage Layout. (line 122)
+* PROMOTE_FUNCTION_ARGS: Storage Layout. (line 111)
+* PROMOTE_FUNCTION_RETURN: Storage Layout. (line 115)
+* PROMOTE_MODE: Storage Layout. (line 88)
+* PROMOTE_PROTOTYPES: Stack Arguments. (line 10)
+* pseudo registers: Regs and Memory. (line 9)
+* PSImode: Machine Modes. (line 32)
+* PTRDIFF_TYPE: Type Layout. (line 123)
+* PTRMEM_CST: Expression trees. (line 6)
+* PTRMEM_CST_CLASS: Expression trees. (line 6)
+* PTRMEM_CST_MEMBER: Expression trees. (line 6)
+* push address instruction: Simple Constraints. (line 152)
+* PUSH_ARGS: Stack Arguments. (line 18)
+* push_reload: Addressing Modes. (line 194)
+* PUSH_ROUNDING: Stack Arguments. (line 26)
+* PUSH_ROUNDING, interaction with PREFERRED_STACK_BOUNDARY: Storage Layout.
+ (line 154)
+* pushM instruction pattern: Standard Names. (line 154)
+* PUT_CODE: RTL Objects. (line 47)
+* PUT_MODE: Machine Modes. (line 178)
+* PUT_REG_NOTE_KIND: Insns. (line 307)
+* PUT_SDB_...: SDB and DWARF. (line 52)
+* QCmode: Machine Modes. (line 111)
+* QFmode: Machine Modes. (line 54)
+* QImode: Machine Modes. (line 25)
+* QImode, in insn: Insns. (line 225)
+* qualified type: Types. (line 6)
+* question mark: Multi-Alternative. (line 41)
+* quotient: Arithmetic. (line 99)
+* r in constraint: Simple Constraints. (line 54)
+* RDIV_EXPR: Expression trees. (line 6)
+* READONLY_DATA_SECTION: Sections. (line 94)
+* REAL_ARITHMETIC: Cross-compilation. (line 98)
+* REAL_CST: Expression trees. (line 6)
+* REAL_INFINITY: Cross-compilation. (line 79)
+* REAL_NM_FILE_NAME: Macros for Initialization.
+ (line 110)
+* REAL_TYPE: Types. (line 6)
+* REAL_VALUE_ATOF: Cross-compilation. (line 73)
+* REAL_VALUE_FIX: Cross-compilation. (line 51)
+* REAL_VALUE_FROM_INT: Cross-compilation. (line 141)
+* REAL_VALUE_ISINF: Cross-compilation. (line 83)
+* REAL_VALUE_ISNAN: Cross-compilation. (line 88)
+* REAL_VALUE_LDEXP: Cross-compilation. (line 45)
+* REAL_VALUE_NEGATE: Cross-compilation. (line 114)
+* REAL_VALUE_RNDZINT: Cross-compilation. (line 61)
+* REAL_VALUE_TO_DECIMAL: Data Output. (line 157)
+* REAL_VALUE_TO_INT: Cross-compilation. (line 135)
+* REAL_VALUE_TO_TARGET_DOUBLE: Data Output. (line 144)
+* REAL_VALUE_TO_TARGET_LONG_DOUBLE: Data Output. (line 144)
+* REAL_VALUE_TO_TARGET_SINGLE: Data Output. (line 144)
+* REAL_VALUE_TRUNCATE: Cross-compilation. (line 123)
+* REAL_VALUE_TYPE: Cross-compilation. (line 31)
+* REAL_VALUE_UNSIGNED_FIX: Cross-compilation. (line 56)
+* REAL_VALUE_UNSIGNED_RNDZINT: Cross-compilation. (line 67)
+* REAL_VALUES_EQUAL: Cross-compilation. (line 36)
+* REAL_VALUES_LESS: Cross-compilation. (line 40)
+* REALPART_EXPR: Expression trees. (line 6)
+* recog_data.operand: Instruction Output. (line 39)
+* recognizing insns: RTL Template. (line 6)
+* RECORD_TYPE <1>: Classes. (line 6)
+* RECORD_TYPE: Types. (line 6)
+* reference: Types. (line 6)
+* REFERENCE_TYPE: Types. (line 6)
+* reg: Regs and Memory. (line 9)
+* reg and /f: Flags. (line 115)
+* reg and /i: Flags. (line 105)
+* reg and /s: Flags. (line 110)
+* reg and /u: Flags. (line 159)
+* reg and /v: Flags. (line 119)
+* reg, RTL sharing: Sharing. (line 17)
+* REG_ALLOC_ORDER: Allocation Order. (line 8)
+* REG_BR_PRED: Insns. (line 511)
+* REG_BR_PROB: Insns. (line 505)
+* REG_CC_SETTER: Insns. (line 475)
+* REG_CC_USER: Insns. (line 475)
+* REG_CLASS_CONTENTS: Register Classes. (line 85)
+* REG_CLASS_FROM_LETTER: Register Classes. (line 123)
+* REG_CLASS_NAMES: Register Classes. (line 80)
+* REG_DEAD: Insns. (line 318)
+* REG_DEP_ANTI: Insns. (line 490)
+* REG_DEP_OUTPUT: Insns. (line 493)
+* REG_EQUAL: Insns. (line 374)
+* REG_EQUIV: Insns. (line 374)
+* REG_EXEC_COUNT: Insns. (line 500)
+* REG_FRAME_RELATED_EXPR: Insns. (line 517)
+* REG_FUNCTION_VALUE_P: Flags. (line 105)
+* REG_INC: Insns. (line 334)
+* REG_LABEL: Insns. (line 364)
+* REG_LIBCALL: Insns. (line 468)
+* REG_LOOP_TEST_P: Flags. (line 110)
+* REG_MODE_OK_FOR_BASE_P: Addressing Modes. (line 116)
+* reg_names: Instruction Output. (line 85)
+* REG_NO_CONFLICT: Insns. (line 348)
+* REG_NONNEG: Insns. (line 340)
+* REG_NOTE_KIND: Insns. (line 307)
+* REG_NOTES: Insns. (line 275)
+* REG_OK_FOR_BASE_P: Addressing Modes. (line 107)
+* REG_OK_FOR_INDEX_P: Addressing Modes. (line 124)
+* REG_OK_STRICT: Addressing Modes. (line 65)
+* REG_PARM_STACK_SPACE: Stack Arguments. (line 50)
+* REG_PARM_STACK_SPACE, and FUNCTION_ARG: Register Arguments. (line 52)
+* REG_POINTER: Flags. (line 115)
+* REG_RETVAL: Insns. (line 452)
+* REG_UNUSED: Insns. (line 327)
+* REG_USERVAR_P: Flags. (line 119)
+* REG_WAS_0: Insns. (line 442)
+* register allocation: Passes. (line 329)
+* register allocation order: Allocation Order. (line 6)
+* register class definitions: Register Classes. (line 6)
+* register class preference constraints: Class Preferences. (line 6)
+* register class preference pass: Passes. (line 325)
+* register movement: Passes. (line 299)
+* register pairs: Values in Registers. (line 34)
+* Register Transfer Language (RTL): RTL. (line 6)
+* register usage: Registers. (line 6)
+* register use analysis: Passes. (line 168)
+* register-to-stack conversion: Passes. (line 397)
+* REGISTER_MOVE_COST: Costs. (line 90)
+* REGISTER_NAMES: Instruction Output. (line 8)
+* register_operand: RTL Template. (line 62)
+* REGISTER_PREFIX: Instruction Output. (line 129)
+* REGISTER_TARGET_PRAGMAS: Misc. (line 298)
+* registers arguments: Register Arguments. (line 6)
+* registers in constraints: Simple Constraints. (line 54)
+* REGNO_MODE_OK_FOR_BASE_P: Register Classes. (line 137)
+* REGNO_OK_FOR_BASE_P: Register Classes. (line 131)
+* REGNO_OK_FOR_INDEX_P: Register Classes. (line 145)
+* REGNO_REG_CLASS: Register Classes. (line 100)
+* regs_ever_live: Function Entry. (line 21)
+* relative costs: Costs. (line 6)
+* RELATIVE_PREFIX_NOT_LINKDIR: Driver. (line 288)
+* reload pass: Regs and Memory. (line 148)
+* reload_completed: Standard Names. (line 537)
+* reload_in instruction pattern: Standard Names. (line 101)
+* reload_in_progress: Standard Names. (line 57)
+* reload_out instruction pattern: Standard Names. (line 101)
+* reloading: Passes. (line 342)
+* remainder: Arithmetic. (line 113)
+* reordering, block: Passes. (line 369)
+* representation of RTL: RTL. (line 6)
+* rest_of_compilation: Passes. (line 19)
+* rest_of_decl_compilation: Passes. (line 19)
+* restore_stack_block instruction pattern: Standard Names. (line 676)
+* restore_stack_function instruction pattern: Standard Names. (line 676)
+* restore_stack_nonlocal instruction pattern: Standard Names. (line 676)
+* RESULT_DECL: Declarations. (line 6)
+* return: Side Effects. (line 67)
+* return instruction pattern: Standard Names. (line 524)
+* return values in registers: Scalar Return. (line 6)
+* RETURN_ADDR_IN_PREVIOUS_FRAME: Frame Layout. (line 108)
+* RETURN_ADDR_RTX: Frame Layout. (line 97)
+* RETURN_ADDRESS_POINTER_REGNUM: Frame Registers. (line 50)
+* RETURN_EXPR: Function Bodies. (line 6)
+* RETURN_IN_MEMORY: Aggregate Return. (line 15)
+* RETURN_INIT: Function Bodies. (line 6)
+* RETURN_POPS_ARGS: Stack Arguments. (line 109)
+* RETURN_STMT: Function Bodies. (line 6)
+* returning aggregate values: Aggregate Return. (line 6)
+* returning structures and unions: Interface. (line 10)
+* REVERSE_CONDEXEC_PREDICATES_P: Condition Code. (line 143)
+* REVERSE_CONDITION (CODE, MODE): Condition Code. (line 131)
+* REVERSIBLE_CC_MODE: Condition Code. (line 117)
+* right rotate: Arithmetic. (line 160)
+* right shift: Arithmetic. (line 155)
+* rotate: Arithmetic. (line 160)
+* rotatert: Arithmetic. (line 160)
+* rotlM3 instruction pattern: Standard Names. (line 224)
+* rotrM3 instruction pattern: Standard Names. (line 224)
+* ROUND_TYPE_ALIGN: Storage Layout. (line 340)
+* ROUND_TYPE_SIZE: Storage Layout. (line 327)
+* ROUND_TYPE_SIZE_UNIT: Storage Layout. (line 334)
+* RSHIFT_EXPR: Expression trees. (line 6)
+* RTL addition: Arithmetic. (line 14)
+* RTL addition with signed saturation: Arithmetic. (line 30)
+* RTL addition with unsigned saturation: Arithmetic. (line 33)
+* RTL classes: RTL Classes. (line 6)
+* RTL comparison: Arithmetic. (line 42)
+* RTL comparison operations: Comparisons. (line 6)
+* RTL constant expression types: Constants. (line 6)
+* RTL constants: Constants. (line 6)
+* RTL declarations: RTL Declarations. (line 6)
+* RTL difference: Arithmetic. (line 27)
+* RTL expression: RTL Objects. (line 6)
+* RTL expressions for arithmetic: Arithmetic. (line 6)
+* RTL format: RTL Classes. (line 63)
+* RTL format characters: RTL Classes. (line 68)
+* RTL function-call insns: Calls. (line 6)
+* RTL generation: Passes. (line 90)
+* RTL insn template: RTL Template. (line 6)
+* RTL integers: RTL Objects. (line 6)
+* RTL memory expressions: Regs and Memory. (line 6)
+* RTL object types: RTL Objects. (line 6)
+* RTL postdecrement: Incdec. (line 6)
+* RTL postincrement: Incdec. (line 6)
+* RTL predecrement: Incdec. (line 6)
+* RTL preincrement: Incdec. (line 6)
+* RTL register expressions: Regs and Memory. (line 6)
+* RTL representation: RTL. (line 6)
+* RTL side effect expressions: Side Effects. (line 6)
+* RTL strings: RTL Objects. (line 6)
+* RTL structure sharing assumptions: Sharing. (line 6)
+* RTL subtraction: Arithmetic. (line 27)
+* RTL sum: Arithmetic. (line 14)
+* RTL vectors: RTL Objects. (line 6)
+* RTX (See RTL): RTL Objects. (line 6)
+* RTX codes, classes of: RTL Classes. (line 6)
+* RTX_COSTS: Costs. (line 23)
+* RTX_FRAME_RELATED_P: Flags. (line 128)
+* RTX_INTEGRATED_P: Flags. (line 154)
+* RTX_UNCHANGING_P: Flags. (line 159)
+* run-time conventions: Interface. (line 6)
+* run-time target specification: Run-time Target. (line 6)
+* s in constraint: Simple Constraints. (line 90)
+* same_type_p: Types. (line 103)
+* save_stack_block instruction pattern: Standard Names. (line 676)
+* save_stack_function instruction pattern: Standard Names. (line 676)
+* save_stack_nonlocal instruction pattern: Standard Names. (line 676)
+* saveable_obstack: Addressing Modes. (line 96)
+* scalars, returned as values: Scalar Return. (line 6)
+* SCCS_DIRECTIVE: Misc. (line 284)
+* SCHED_GROUP_P: Flags. (line 164)
+* scheduling, delayed branch: Passes. (line 381)
+* scheduling, instruction: Passes. (line 309)
+* SCmode: Machine Modes. (line 111)
+* sCOND instruction pattern: Standard Names. (line 414)
+* SCOPE_BEGIN_P: Function Bodies. (line 6)
+* SCOPE_END_P: Function Bodies. (line 6)
+* SCOPE_NULLIFIED_P: Function Bodies. (line 6)
+* SCOPE_STMT: Function Bodies. (line 6)
+* scratch: Regs and Memory. (line 173)
+* scratch operands: Regs and Memory. (line 173)
+* scratch, RTL sharing: Sharing. (line 35)
+* SDB_ALLOW_FORWARD_REFERENCES: SDB and DWARF. (line 75)
+* SDB_ALLOW_UNKNOWN_REFERENCES: SDB and DWARF. (line 70)
+* SDB_DEBUGGING_INFO: SDB and DWARF. (line 8)
+* SDB_DELIM: SDB and DWARF. (line 58)
+* SDB_GENERATE_FAKE: SDB and DWARF. (line 65)
+* search options: Including Patterns. (line 45)
+* SECONDARY_INPUT_RELOAD_CLASS: Register Classes. (line 201)
+* SECONDARY_MEMORY_NEEDED: Register Classes. (line 264)
+* SECONDARY_MEMORY_NEEDED_MODE: Register Classes. (line 283)
+* SECONDARY_MEMORY_NEEDED_RTX: Register Classes. (line 274)
+* SECONDARY_OUTPUT_RELOAD_CLASS: Register Classes. (line 201)
+* SECONDARY_RELOAD_CLASS: Register Classes. (line 201)
+* SELECT_CC_MODE: Condition Code. (line 84)
+* SELECT_RTX_SECTION: Sections. (line 117)
+* SELECT_SECTION: Sections. (line 104)
+* sequence: Side Effects. (line 245)
+* set: Side Effects. (line 15)
+* SET_ASM_OP: Label Output. (line 243)
+* set_attr: Tagging Insns. (line 31)
+* set_attr_alternative: Tagging Insns. (line 49)
+* SET_DEST: Side Effects. (line 64)
+* SET_IS_RETURN_P: Flags. (line 172)
+* SET_SRC: Side Effects. (line 64)
+* SETUP_FRAME_ADDRESSES: Frame Layout. (line 82)
+* SETUP_INCOMING_VARARGS: Varargs. (line 98)
+* SFmode: Machine Modes. (line 66)
+* SHARED_BSS_SECTION_ASM_OP: Sections. (line 48)
+* SHARED_SECTION_ASM_OP: Sections. (line 33)
+* sharing of RTL components: Sharing. (line 6)
+* shift: Arithmetic. (line 147)
+* SHIFT_COUNT_TRUNCATED: Misc. (line 117)
+* SHORT_IMMEDIATES_SIGN_EXTEND: Misc. (line 96)
+* SHORT_TYPE_SIZE: Type Layout. (line 15)
+* sibcall_epilogue instruction pattern: Standard Names. (line 878)
+* sibling call optimization: Passes. (line 135)
+* SIBLING_CALL_P: Flags. (line 176)
+* sign_extend: Conversions. (line 24)
+* sign_extract: Bit-Fields. (line 11)
+* sign_extract, canonicalization of: Insn Canonicalizations.
+ (line 81)
+* signed division: Arithmetic. (line 99)
+* signed maximum: Arithmetic. (line 118)
+* signed minimum: Arithmetic. (line 118)
+* SImode: Machine Modes. (line 37)
+* simple constraints: Simple Constraints. (line 6)
+* simplifications, arithmetic: Passes. (line 86)
+* Single Static Assignment optimizations: Passes. (line 178)
+* SIZE_TYPE: Type Layout. (line 107)
+* SLOW_BYTE_ACCESS: Costs. (line 140)
+* SLOW_UNALIGNED_ACCESS: Costs. (line 155)
+* SMALL_ARG_MAX: Host Config. (line 116)
+* SMALL_REGISTER_CLASSES: Register Classes. (line 306)
+* SMALL_STACK: Frame Layout. (line 154)
+* smax: Arithmetic. (line 118)
+* smaxM3 instruction pattern: Standard Names. (line 167)
+* smin: Arithmetic. (line 118)
+* sminM3 instruction pattern: Standard Names. (line 167)
+* smulM3_highpart instruction pattern: Standard Names. (line 189)
+* SPECIAL_MODE_PREDICATES: Misc. (line 34)
+* speed of instructions: Costs. (line 6)
+* splitting instructions: Insn Splitting. (line 6)
+* sqrt: Arithmetic. (line 168)
+* sqrtM2 instruction pattern: Standard Names. (line 234)
+* square root: Arithmetic. (line 168)
+* ss_minus: Arithmetic. (line 36)
+* ss_plus: Arithmetic. (line 30)
+* ss_truncate: Conversions. (line 44)
+* SSA Conditional Constant Propagation: Passes. (line 190)
+* SSA DCE: Passes. (line 201)
+* SSA optimizations: Passes. (line 178)
+* stack arguments: Stack Arguments. (line 6)
+* stack frame layout: Frame Layout. (line 6)
+* STACK_BOUNDARY: Storage Layout. (line 134)
+* STACK_CHECK_BUILTIN: Stack Checking. (line 28)
+* STACK_CHECK_FIXED_FRAME_SIZE: Stack Checking. (line 63)
+* STACK_CHECK_MAX_FRAME_SIZE: Stack Checking. (line 54)
+* STACK_CHECK_MAX_VAR_SIZE: Stack Checking. (line 70)
+* STACK_CHECK_PROBE_INTERVAL: Stack Checking. (line 36)
+* STACK_CHECK_PROBE_LOAD: Stack Checking. (line 43)
+* STACK_CHECK_PROTECT: Stack Checking. (line 49)
+* STACK_DYNAMIC_OFFSET: Frame Layout. (line 64)
+* STACK_DYNAMIC_OFFSET and virtual registers: Regs and Memory.
+ (line 83)
+* STACK_GROWS_DOWNWARD: Frame Layout. (line 8)
+* STACK_PARMS_IN_REG_PARM_AREA: Stack Arguments. (line 100)
+* STACK_POINTER_OFFSET: Frame Layout. (line 47)
+* STACK_POINTER_OFFSET and virtual registers: Regs and Memory.
+ (line 93)
+* STACK_POINTER_REGNUM: Frame Registers. (line 8)
+* STACK_POINTER_REGNUM and virtual registers: Regs and Memory.
+ (line 83)
+* stack_pointer_rtx: Frame Registers. (line 85)
+* STACK_PUSH_CODE: Frame Layout. (line 16)
+* STACK_REGS: Stack Registers. (line 14)
+* STACK_SAVEAREA_MODE: Storage Layout. (line 361)
+* STACK_SIZE_MODE: Storage Layout. (line 373)
+* standard pattern names: Standard Names. (line 6)
+* STANDARD_EXEC_PREFIX: Driver. (line 293)
+* STANDARD_INCLUDE_COMPONENT: Driver. (line 378)
+* STANDARD_INCLUDE_DIR: Driver. (line 370)
+* STANDARD_STARTFILE_PREFIX: Driver. (line 306)
+* STARTFILE_SPEC: Driver. (line 175)
+* STARTING_FRAME_OFFSET: Frame Layout. (line 38)
+* STARTING_FRAME_OFFSET and virtual registers: Regs and Memory.
+ (line 74)
+* statements: Function Bodies. (line 6)
+* STATIC_CHAIN: Frame Registers. (line 76)
+* STATIC_CHAIN_INCOMING: Frame Registers. (line 76)
+* STATIC_CHAIN_INCOMING_REGNUM: Frame Registers. (line 62)
+* STATIC_CHAIN_REGNUM: Frame Registers. (line 62)
+* stdarg.h and register arguments: Register Arguments. (line 47)
+* STDC_0_IN_SYSTEM_HEADERS: Misc. (line 273)
+* STMT_EXPR: Expression trees. (line 6)
+* STMT_IS_FULL_EXPR_P: Function Bodies. (line 35)
+* STMT_LINENO: Function Bodies. (line 23)
+* storage layout: Storage Layout. (line 6)
+* STORE_FLAG_VALUE: Misc. (line 156)
+* store_multiple instruction pattern: Standard Names. (line 148)
+* strcpy: Storage Layout. (line 202)
+* strength-reduction: Passes. (line 243)
+* STRICT_ALIGNMENT: Storage Layout. (line 246)
+* STRICT_ARGUMENT_NAMING: Varargs. (line 132)
+* strict_low_part: RTL Declarations. (line 9)
+* strict_memory_address_p: Addressing Modes. (line 204)
+* STRING_CST: Expression trees. (line 6)
+* STRING_POOL_ADDRESS_P: Flags. (line 180)
+* STRIP_NAME_ENCODING: Sections. (line 156)
+* strlenM instruction pattern: Standard Names. (line 320)
+* STRUCT_VALUE: Aggregate Return. (line 47)
+* STRUCT_VALUE_INCOMING: Aggregate Return. (line 62)
+* STRUCT_VALUE_INCOMING_REGNUM: Aggregate Return. (line 53)
+* STRUCT_VALUE_REGNUM: Aggregate Return. (line 43)
+* structure value address: Aggregate Return. (line 6)
+* STRUCTURE_SIZE_BOUNDARY: Storage Layout. (line 238)
+* structures, returning: Interface. (line 10)
+* subM3 instruction pattern: Standard Names. (line 167)
+* SUBOBJECT: Function Bodies. (line 6)
+* SUBOBJECT_CLEANUP: Function Bodies. (line 6)
+* subreg: Regs and Memory. (line 97)
+* subreg and /s: Flags. (line 191)
+* subreg and /u: Flags. (line 185)
+* subreg, in strict_low_part: RTL Declarations. (line 9)
+* subreg, special reload handling: Regs and Memory. (line 148)
+* SUBREG_BYTE: Regs and Memory. (line 169)
+* SUBREG_PROMOTED_UNSIGNED_P: Flags. (line 185)
+* SUBREG_PROMOTED_VAR_P: Flags. (line 191)
+* SUBREG_REG: Regs and Memory. (line 169)
+* SUCCESS_EXIT_CODE: Host Config. (line 24)
+* SUPPORTS_INIT_PRIORITY: Macros for Initialization.
+ (line 58)
+* SUPPORTS_ONE_ONLY: Label Output. (line 113)
+* SUPPORTS_WEAK: Label Output. (line 94)
+* SWITCH_BODY: Function Bodies. (line 6)
+* SWITCH_COND: Function Bodies. (line 6)
+* SWITCH_CURTAILS_COMPILATION: Driver. (line 32)
+* SWITCH_STMT: Function Bodies. (line 6)
+* SWITCH_TAKES_ARG: Driver. (line 8)
+* SWITCHES_NEED_SPACES: Driver. (line 46)
+* symbol_ref: Constants. (line 84)
+* symbol_ref and /f: Flags. (line 180)
+* symbol_ref and /i: Flags. (line 210)
+* symbol_ref and /u: Flags. (line 10)
+* symbol_ref and /v: Flags. (line 201)
+* symbol_ref, RTL sharing: Sharing. (line 20)
+* SYMBOL_REF_FLAG: Flags. (line 201)
+* SYMBOL_REF_FLAG, in ENCODE_SECTION_INFO: Sections. (line 151)
+* SYMBOL_REF_USED: Flags. (line 205)
+* SYMBOL_REF_WEAK: Flags. (line 210)
+* symbolic label: Sharing. (line 20)
+* SYSTEM_INCLUDE_DIR: Driver. (line 361)
+* t-TARGET: Target Fragment. (line 6)
+* tablejump instruction pattern: Standard Names. (line 604)
+* tagging insns: Tagging Insns. (line 6)
+* tail calls: Tail Calls. (line 6)
+* tail recursion optimization: Passes. (line 99)
+* target attributes: Target Attributes. (line 6)
+* target description macros: Target Macros. (line 6)
+* target functions: Target Structure. (line 6)
+* target hooks: Target Structure. (line 6)
+* target makefile fragment: Target Fragment. (line 6)
+* target specifications: Run-time Target. (line 6)
+* target-parameter-dependent code: Passes. (line 93)
+* TARGET_ALLOWS_PROFILING_WITHOUT_FRAME_POINTER: Profiling. (line 39)
+* TARGET_ASM_ALIGNED_DI_OP: Data Output. (line 10)
+* TARGET_ASM_ALIGNED_HI_OP: Data Output. (line 8)
+* TARGET_ASM_ALIGNED_SI_OP: Data Output. (line 9)
+* TARGET_ASM_ALIGNED_TI_OP: Data Output. (line 11)
+* TARGET_ASM_BYTE_OP: Data Output. (line 7)
+* TARGET_ASM_CLOSE_PAREN: Data Output. (line 133)
+* TARGET_ASM_CONSTRUCTOR: Macros for Initialization.
+ (line 69)
+* TARGET_ASM_DESTRUCTOR: Macros for Initialization.
+ (line 83)
+* TARGET_ASM_EH_FRAME_SECTION: Exception Region Output.
+ (line 67)
+* TARGET_ASM_EXCEPTION_SECTION: Exception Region Output.
+ (line 59)
+* TARGET_ASM_FUNCTION_BEGIN_EPILOGUE: Function Entry. (line 61)
+* TARGET_ASM_FUNCTION_END_PROLOGUE: Function Entry. (line 55)
+* TARGET_ASM_FUNCTION_EPILOGUE: Function Entry. (line 68)
+* TARGET_ASM_FUNCTION_EPILOGUE and trampolines: Trampolines. (line 76)
+* TARGET_ASM_FUNCTION_PROLOGUE: Function Entry. (line 11)
+* TARGET_ASM_FUNCTION_PROLOGUE and trampolines: Trampolines. (line 76)
+* TARGET_ASM_INTEGER: Data Output. (line 27)
+* TARGET_ASM_NAMED_SECTION: File Framework. (line 86)
+* TARGET_ASM_OPEN_PAREN: Data Output. (line 132)
+* TARGET_ASM_UNALIGNED_DI_OP: Data Output. (line 14)
+* TARGET_ASM_UNALIGNED_HI_OP: Data Output. (line 12)
+* TARGET_ASM_UNALIGNED_SI_OP: Data Output. (line 13)
+* TARGET_ASM_UNALIGNED_TI_OP: Data Output. (line 15)
+* TARGET_ATTRIBUTE_TABLE: Target Attributes. (line 11)
+* TARGET_BELL: Escape Sequences. (line 10)
+* TARGET_BS: Escape Sequences. (line 19)
+* TARGET_CANNOT_MODIFY_JUMPS_P: Misc. (line 593)
+* TARGET_COMP_TYPE_ATTRIBUTES: Target Attributes. (line 19)
+* TARGET_CR: Escape Sequences. (line 25)
+* TARGET_DLLIMPORT_DECL_ATTRIBUTES: Target Attributes. (line 47)
+* TARGET_EDOM: Library Calls. (line 81)
+* TARGET_ESC: Escape Sequences. (line 14)
+* TARGET_EXECUTABLE_SUFFIX: Misc. (line 578)
+* TARGET_EXPAND_BUILTIN: Misc. (line 540)
+* TARGET_FF: Escape Sequences. (line 25)
+* TARGET_FLOAT_FORMAT: Storage Layout. (line 396)
+* TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P: Target Attributes. (line 69)
+* TARGET_HAS_F_SETLKW: Misc. (line 488)
+* TARGET_HAVE_CTORS_DTORS: Macros for Initialization.
+ (line 64)
+* TARGET_HAVE_NAMED_SECTIONS: File Framework. (line 96)
+* TARGET_INIT_BUILTINS: Misc. (line 523)
+* TARGET_INSERT_ATTRIBUTES: Target Attributes. (line 56)
+* TARGET_MEM_FUNCTIONS: Library Calls. (line 99)
+* TARGET_MERGE_DECL_ATTRIBUTES: Target Attributes. (line 39)
+* TARGET_MERGE_TYPE_ATTRIBUTES: Target Attributes. (line 31)
+* TARGET_MS_BITFIELD_LAYOUT_P: Storage Layout. (line 427)
+* TARGET_NEWLINE: Escape Sequences. (line 19)
+* TARGET_OBJECT_SUFFIX: Misc. (line 573)
+* TARGET_OPTION_TRANSLATE_TABLE: Driver. (line 52)
+* TARGET_OPTIONS: Run-time Target. (line 90)
+* TARGET_PTRMEMFUNC_VBIT_LOCATION: Type Layout. (line 189)
+* TARGET_SCHED_ADJUST_COST: Scheduling. (line 32)
+* TARGET_SCHED_ADJUST_PRIORITY: Scheduling. (line 41)
+* TARGET_SCHED_CYCLE_DISPLAY: Scheduling. (line 96)
+* TARGET_SCHED_FINISH: Scheduling. (line 88)
+* TARGET_SCHED_INIT: Scheduling. (line 78)
+* TARGET_SCHED_ISSUE_RATE: Scheduling. (line 12)
+* TARGET_SCHED_REORDER: Scheduling. (line 49)
+* TARGET_SCHED_REORDER2: Scheduling. (line 66)
+* TARGET_SCHED_VARIABLE_ISSUE: Scheduling. (line 20)
+* TARGET_SECTION_TYPE_FLAGS: File Framework. (line 101)
+* TARGET_SET_DEFAULT_TYPE_ATTRIBUTES: Target Attributes. (line 26)
+* TARGET_SWITCHES: Run-time Target. (line 55)
+* TARGET_TAB: Escape Sequences. (line 19)
+* TARGET_VERSION: Run-time Target. (line 117)
+* TARGET_VT: Escape Sequences. (line 25)
+* TARGET_VTABLE_USES_DESCRIPTORS: Type Layout. (line 225)
+* targetm: Target Structure. (line 7)
+* targets, makefile: Makefile. (line 6)
+* TCmode: Machine Modes. (line 111)
+* TEMPLATE_DECL: Declarations. (line 6)
+* termination routines: Initialization. (line 6)
+* text_section: Sections. (line 88)
+* TEXT_SECTION: Sections. (line 22)
+* TEXT_SECTION_ASM_OP: Sections. (line 17)
+* TFmode: Machine Modes. (line 84)
+* THEN_CLAUSE: Function Bodies. (line 6)
+* THREAD_MODEL_SPEC: Driver. (line 190)
+* THROW_EXPR: Expression trees. (line 6)
+* THUNK_DECL: Declarations. (line 6)
+* THUNK_DELTA: Declarations. (line 6)
+* TImode: Machine Modes. (line 48)
+* TImode, in insn: Insns. (line 225)
+* tm.h macros: Target Macros. (line 6)
+* top level of compiler: Passes. (line 6)
+* TQFmode: Machine Modes. (line 62)
+* TRADITIONAL_RETURN_FLOAT: Scalar Return. (line 9)
+* TRAMPOLINE_ADJUST_ADDRESS: Trampolines. (line 62)
+* TRAMPOLINE_ALIGNMENT: Trampolines. (line 49)
+* TRAMPOLINE_SECTION: Trampolines. (line 39)
+* TRAMPOLINE_SIZE: Trampolines. (line 45)
+* TRAMPOLINE_TEMPLATE: Trampolines. (line 28)
+* trampolines for nested functions: Trampolines. (line 6)
+* TRANSFER_FROM_TRAMPOLINE: Trampolines. (line 138)
+* trap instruction pattern: Standard Names. (line 888)
+* tree <1>: Macros and Functions.
+ (line 6)
+* tree: Tree overview. (line 6)
+* Tree optimization: Passes. (line 77)
+* TREE_CODE: Tree overview. (line 6)
+* tree_int_cst_equal: Expression trees. (line 6)
+* TREE_INT_CST_HIGH: Expression trees. (line 6)
+* TREE_INT_CST_LOW: Expression trees. (line 6)
+* tree_int_cst_lt: Expression trees. (line 6)
+* TREE_LIST: Containers. (line 6)
+* TREE_OPERAND: Expression trees. (line 6)
+* TREE_PUBLIC: Function Basics. (line 6)
+* TREE_PURPOSE: Containers. (line 6)
+* TREE_STRING_LENGTH: Expression trees. (line 6)
+* TREE_STRING_POINTER: Expression trees. (line 6)
+* TREE_TYPE <1>: Expression trees. (line 17)
+* TREE_TYPE <2>: Function Basics. (line 164)
+* TREE_TYPE <3>: Declarations. (line 16)
+* TREE_TYPE: Types. (line 6)
+* TREE_VALUE: Containers. (line 6)
+* TREE_VEC: Containers. (line 6)
+* TREE_VEC_ELT: Containers. (line 6)
+* TREE_VEC_LENGTH: Containers. (line 6)
+* TREE_VIA_PRIVATE: Classes. (line 6)
+* TREE_VIA_PROTECTED: Classes. (line 6)
+* TREE_VIA_PUBLIC: Classes. (line 6)
+* Trees: Trees. (line 6)
+* TRULY_NOOP_TRUNCATION: Misc. (line 143)
+* TRUNC_DIV_EXPR: Expression trees. (line 6)
+* TRUNC_MOD_EXPR: Expression trees. (line 6)
+* truncate: Conversions. (line 39)
+* truncMN2 instruction pattern: Standard Names. (line 360)
+* TRUTH_AND_EXPR: Expression trees. (line 6)
+* TRUTH_ANDIF_EXPR: Expression trees. (line 6)
+* TRUTH_NOT_EXPR: Expression trees. (line 6)
+* TRUTH_OR_EXPR: Expression trees. (line 6)
+* TRUTH_ORIF_EXPR: Expression trees. (line 6)
+* TRUTH_XOR_EXPR: Expression trees. (line 6)
+* TRY_BLOCK: Function Bodies. (line 6)
+* TRY_HANDLERS: Function Bodies. (line 6)
+* TRY_STMTS: Function Bodies. (line 6)
+* tstM instruction pattern: Standard Names. (line 260)
+* type: Types. (line 6)
+* type declaration: Declarations. (line 6)
+* TYPE_ALIGN: Types. (line 6)
+* TYPE_ARG_TYPES: Types. (line 6)
+* TYPE_ATTRIBUTES: Attributes. (line 25)
+* TYPE_BINFO: Classes. (line 6)
+* TYPE_BUILT_IN: Types. (line 84)
+* TYPE_CONTEXT: Types. (line 6)
+* TYPE_DECL: Declarations. (line 6)
+* TYPE_FIELDS <1>: Classes. (line 6)
+* TYPE_FIELDS: Types. (line 6)
+* TYPE_HAS_ARRAY_NEW_OPERATOR: Classes. (line 90)
+* TYPE_HAS_DEFAULT_CONSTRUCTOR: Classes. (line 74)
+* TYPE_HAS_MUTABLE_P: Classes. (line 80)
+* TYPE_HAS_NEW_OPERATOR: Classes. (line 87)
+* TYPE_MAIN_VARIANT: Types. (line 6)
+* TYPE_MAX_VALUE: Types. (line 6)
+* TYPE_METHOD_BASETYPE: Types. (line 6)
+* TYPE_METHODS: Classes. (line 6)
+* TYPE_MIN_VALUE: Types. (line 6)
+* TYPE_NAME: Types. (line 6)
+* TYPE_NOTHROW_P: Function Basics. (line 173)
+* TYPE_OFFSET_BASETYPE: Types. (line 6)
+* TYPE_OVERLOADS_ARRAY_REF: Classes. (line 98)
+* TYPE_OVERLOADS_ARROW: Classes. (line 101)
+* TYPE_OVERLOADS_CALL_EXPR: Classes. (line 94)
+* TYPE_POLYMORPHIC_P: Classes. (line 70)
+* TYPE_PRECISION: Types. (line 6)
+* TYPE_PTR_P: Types. (line 90)
+* TYPE_PTRFN_P: Types. (line 94)
+* TYPE_PTRMEM_P: Types. (line 6)
+* TYPE_PTROB_P: Types. (line 97)
+* TYPE_PTROBV_P: Types. (line 6)
+* TYPE_QUAL_CONST: Types. (line 6)
+* TYPE_QUAL_RESTRICT: Types. (line 6)
+* TYPE_QUAL_VOLATILE: Types. (line 6)
+* TYPE_RAISES_EXCEPTIONS: Function Basics. (line 168)
+* TYPE_SIZE: Types. (line 6)
+* TYPE_UNQUALIFIED: Types. (line 6)
+* TYPE_VFIELD: Classes. (line 6)
+* TYPENAME_TYPE: Types. (line 6)
+* TYPENAME_TYPE_FULLNAME: Types. (line 6)
+* TYPEOF_TYPE: Types. (line 6)
+* udiv: Arithmetic. (line 110)
+* UDIVDI3_LIBCALL: Library Calls. (line 50)
+* udivM3 instruction pattern: Standard Names. (line 167)
+* udivmodM4 instruction pattern: Standard Names. (line 214)
+* UDIVSI3_LIBCALL: Library Calls. (line 20)
+* UINTMAX_TYPE: Type Layout. (line 178)
+* umax: Arithmetic. (line 123)
+* umaxM3 instruction pattern: Standard Names. (line 167)
+* umin: Arithmetic. (line 123)
+* uminM3 instruction pattern: Standard Names. (line 167)
+* umod: Arithmetic. (line 113)
+* UMODDI3_LIBCALL: Library Calls. (line 62)
+* umodM3 instruction pattern: Standard Names. (line 167)
+* UMODSI3_LIBCALL: Library Calls. (line 32)
+* umulhisi3 instruction pattern: Standard Names. (line 185)
+* umulM3_highpart instruction pattern: Standard Names. (line 194)
+* umulqihi3 instruction pattern: Standard Names. (line 185)
+* umulsidi3 instruction pattern: Standard Names. (line 185)
+* unchanging: Flags. (line 299)
+* unchanging, in call_insn: Flags. (line 19)
+* unchanging, in insn: Flags. (line 24)
+* unchanging, in reg and mem: Flags. (line 159)
+* unchanging, in subreg: Flags. (line 185)
+* unchanging, in symbol_ref: Flags. (line 10)
+* UNION_TYPE <1>: Classes. (line 6)
+* UNION_TYPE: Types. (line 6)
+* unions, returning: Interface. (line 10)
+* UNIQUE_SECTION: Sections. (line 161)
+* UNITS_PER_WORD: Storage Layout. (line 64)
+* UNKNOWN_FLOAT_FORMAT: Storage Layout. (line 413)
+* UNKNOWN_TYPE: Types. (line 6)
+* unreachable code: Passes. (line 146)
+* unshare_all_rtl: Sharing. (line 58)
+* unsigned division: Arithmetic. (line 110)
+* unsigned greater than: Comparisons. (line 61)
+* unsigned less than: Comparisons. (line 65)
+* unsigned minimum and maximum: Arithmetic. (line 123)
+* unsigned_fix: Conversions. (line 73)
+* unsigned_float: Conversions. (line 63)
+* unspec: Side Effects. (line 278)
+* unspec_volatile: Side Effects. (line 278)
+* untyped_call instruction pattern: Standard Names. (line 509)
+* untyped_return instruction pattern: Standard Names. (line 559)
+* UPDATE_PATH_HOST_CANONICALIZE (PATH): Host Config. (line 96)
+* us_minus: Arithmetic. (line 39)
+* us_plus: Arithmetic. (line 33)
+* us_truncate: Conversions. (line 49)
+* use: Side Effects. (line 153)
+* USE_C_ALLOCA: Host Config. (line 31)
+* USE_LOAD_POST_DECREMENT: Costs. (line 205)
+* USE_LOAD_POST_INCREMENT: Costs. (line 200)
+* USE_LOAD_PRE_DECREMENT: Costs. (line 215)
+* USE_LOAD_PRE_INCREMENT: Costs. (line 210)
+* USE_STORE_POST_DECREMENT: Costs. (line 225)
+* USE_STORE_POST_INCREMENT: Costs. (line 220)
+* USE_STORE_PRE_DECREMENT: Costs. (line 235)
+* USE_STORE_PRE_INCREMENT: Costs. (line 230)
+* used: Flags. (line 316)
+* used, in symbol_ref: Flags. (line 205)
+* USER_LABEL_PREFIX: Instruction Output. (line 129)
+* USING_DECL: Declarations. (line 6)
+* USING_STMT: Function Bodies. (line 6)
+* V in constraint: Simple Constraints. (line 41)
+* values, returned by functions: Scalar Return. (line 6)
+* VAR_DECL <1>: Expression trees. (line 6)
+* VAR_DECL: Declarations. (line 6)
+* varargs implementation: Varargs. (line 6)
+* variable: Declarations. (line 6)
+* VAX_FLOAT_FORMAT: Storage Layout. (line 404)
+* vec_concat: Vector Operations. (line 25)
+* vec_const: Vector Operations. (line 30)
+* vec_duplicate: Vector Operations. (line 34)
+* vec_merge: Vector Operations. (line 11)
+* vec_select: Vector Operations. (line 19)
+* vector: Containers. (line 6)
+* vector operations: Vector Operations. (line 6)
+* VECTOR_CST: Expression trees. (line 6)
+* VECTOR_MODE_SUPPORTED_P: Storage Layout. (line 356)
+* VIRTUAL_INCOMING_ARGS_REGNUM: Regs and Memory. (line 59)
+* VIRTUAL_OUTGOING_ARGS_REGNUM: Regs and Memory. (line 87)
+* VIRTUAL_STACK_DYNAMIC_REGNUM: Regs and Memory. (line 78)
+* VIRTUAL_STACK_VARS_REGNUM: Regs and Memory. (line 69)
+* VMS: Host Config. (line 15)
+* VMS_DEBUGGING_INFO: VMS Debug. (line 8)
+* VOID_TYPE: Types. (line 6)
+* VOIDmode: Machine Modes. (line 104)
+* volatil: Flags. (line 330)
+* volatil, in insn: Flags. (line 34)
+* volatil, in label_ref: Flags. (line 59)
+* volatil, in mem: Flags. (line 100)
+* volatil, in reg: Flags. (line 119)
+* volatil, in symbol_ref: Flags. (line 201)
+* volatile memory references: Flags. (line 331)
+* voting between constraint alternatives: Class Preferences. (line 6)
+* VTABLE_REF: Expression trees. (line 6)
+* WCHAR_TYPE: Type Layout. (line 131)
+* WCHAR_TYPE_SIZE: Type Layout. (line 139)
+* which_alternative: Output Statement. (line 59)
+* WHILE_BODY: Function Bodies. (line 6)
+* WHILE_COND: Function Bodies. (line 6)
+* WHILE_STMT: Function Bodies. (line 6)
+* WIDEST_HARDWARE_FP_SIZE: Type Layout. (line 86)
+* WINT_TYPE: Type Layout. (line 159)
+* word_mode: Machine Modes. (line 223)
+* WORD_REGISTER_OPERATIONS: Misc. (line 76)
+* WORD_SWITCH_TAKES_ARG: Driver. (line 19)
+* WORDS_BIG_ENDIAN: Storage Layout. (line 28)
+* WORDS_BIG_ENDIAN, effect on subreg: Regs and Memory. (line 132)
+* X in constraint: Simple Constraints. (line 112)
+* x-HOST: Host Fragment. (line 6)
+* XCmode: Machine Modes. (line 111)
+* XCOFF_DEBUGGING_INFO: DBX Options. (line 12)
+* XEXP: Accessors. (line 6)
+* XFmode: Machine Modes. (line 79)
+* XINT: Accessors. (line 6)
+* xm-MACHINE.h: Host Config. (line 6)
+* xor: Arithmetic. (line 142)
+* xor, canonicalization of: Insn Canonicalizations.
+ (line 69)
+* xorM3 instruction pattern: Standard Names. (line 167)
+* XSTR: Accessors. (line 6)
+* XVEC: Accessors. (line 41)
+* XVECEXP: Accessors. (line 48)
+* XVECLEN: Accessors. (line 44)
+* XWINT: Accessors. (line 6)
+* zero_extend: Conversions. (line 29)
+* zero_extendMN2 instruction pattern: Standard Names. (line 370)
+* zero_extract: Bit-Fields. (line 30)
+* zero_extract, canonicalization of: Insn Canonicalizations.
+ (line 81)
+
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: RTL Classes, Next: Accessors, Prev: RTL Objects, Up: RTL
-
-RTL Classes and Formats
-=======================
-
- The various expression codes are divided into several "classes",
-which are represented by single characters. You can determine the class
-of an RTX code with the macro `GET_RTX_CLASS (CODE)'. Currently,
-`rtx.def' defines these classes:
-
-`o'
- An RTX code that represents an actual object, such as a register
- (`REG') or a memory location (`MEM', `SYMBOL_REF'). Constants and
- basic transforms on objects (`ADDRESSOF', `HIGH', `LO_SUM') are
- also included. Note that `SUBREG' and `STRICT_LOW_PART' are not
- in this class, but in class `x'.
-
-`<'
- An RTX code for a comparison, such as `NE' or `LT'.
-
-`1'
- An RTX code for a unary arithmetic operation, such as `NEG',
- `NOT', or `ABS'. This category also includes value extension
- (sign or zero) and conversions between integer and floating point.
-
-`c'
- An RTX code for a commutative binary operation, such as `PLUS' or
- `AND'. `NE' and `EQ' are comparisons, so they have class `<'.
-
-`2'
- An RTX code for a non-commutative binary operation, such as
- `MINUS', `DIV', or `ASHIFTRT'.
-
-`b'
- An RTX code for a bit-field operation. Currently only
- `ZERO_EXTRACT' and `SIGN_EXTRACT'. These have three inputs and
- are lvalues (so they can be used for insertion as well). *Note
- Bit-Fields::.
-
-`3'
- An RTX code for other three input operations. Currently only
- `IF_THEN_ELSE'.
-
-`i'
- An RTX code for an entire instruction: `INSN', `JUMP_INSN', and
- `CALL_INSN'. *Note Insns::.
-
-`m'
- An RTX code for something that matches in insns, such as
- `MATCH_DUP'. These only occur in machine descriptions.
-
-`a'
- An RTX code for an auto-increment addressing mode, such as
- `POST_INC'.
-
-`x'
- All other RTX codes. This category includes the remaining codes
- used only in machine descriptions (`DEFINE_*', etc.). It also
- includes all the codes describing side effects (`SET', `USE',
- `CLOBBER', etc.) and the non-insns that may appear on an insn
- chain, such as `NOTE', `BARRIER', and `CODE_LABEL'.
-
- For each expression code, `rtl.def' specifies the number of
-contained objects and their kinds using a sequence of characters called
-the "format" of the expression code. For example, the format of
-`subreg' is `ei'.
-
- These are the most commonly used format characters:
-
-`e'
- An expression (actually a pointer to an expression).
-
-`i'
- An integer.
-
-`w'
- A wide integer.
-
-`s'
- A string.
-
-`E'
- A vector of expressions.
-
- A few other format characters are used occasionally:
-
-`u'
- `u' is equivalent to `e' except that it is printed differently in
- debugging dumps. It is used for pointers to insns.
-
-`n'
- `n' is equivalent to `i' except that it is printed differently in
- debugging dumps. It is used for the line number or code number of
- a `note' insn.
-
-`S'
- `S' indicates a string which is optional. In the RTL objects in
- core, `S' is equivalent to `s', but when the object is read, from
- an `md' file, the string value of this operand may be omitted. An
- omitted string is taken to be the null string.
-
-`V'
- `V' indicates a vector which is optional. In the RTL objects in
- core, `V' is equivalent to `E', but when the object is read from
- an `md' file, the vector value of this operand may be omitted. An
- omitted vector is effectively the same as a vector of no elements.
-
-`0'
- `0' means a slot whose contents do not fit any normal category.
- `0' slots are not printed at all in dumps, and are often used in
- special ways by small parts of the compiler.
-
- There are macros to get the number of operands and the format of an
-expression code:
-
-`GET_RTX_LENGTH (CODE)'
- Number of operands of an RTX of code CODE.
-
-`GET_RTX_FORMAT (CODE)'
- The format of an RTX of code CODE, as a C string.
-
- Some classes of RTX codes always have the same format. For example,
-it is safe to assume that all comparison operations have format `ee'.
-
-`1'
- All codes of this class have format `e'.
-
-`<'
-`c'
-`2'
- All codes of these classes have format `ee'.
-
-`b'
-`3'
- All codes of these classes have format `eee'.
-
-`i'
- All codes of this class have formats that begin with `iuueiee'.
- *Note Insns::. Note that not all RTL objects linked onto an insn
- chain are of class `i'.
-
-`o'
-`m'
-`x'
- You can make no assumptions about the format of these codes.
-
-\1f
-File: gccint.info, Node: Accessors, Next: Flags, Prev: RTL Classes, Up: RTL
-
-Access to Operands
-==================
-
- Operands of expressions are accessed using the macros `XEXP',
-`XINT', `XWINT' and `XSTR'. Each of these macros takes two arguments:
-an expression-pointer (RTX) and an operand number (counting from zero).
-Thus,
-
- XEXP (X, 2)
-
-accesses operand 2 of expression X, as an expression.
-
- XINT (X, 2)
-
-accesses the same operand as an integer. `XSTR', used in the same
-fashion, would access it as a string.
-
- Any operand can be accessed as an integer, as an expression or as a
-string. You must choose the correct method of access for the kind of
-value actually stored in the operand. You would do this based on the
-expression code of the containing expression. That is also how you
-would know how many operands there are.
-
- For example, if X is a `subreg' expression, you know that it has two
-operands which can be correctly accessed as `XEXP (X, 0)' and `XINT (X,
-1)'. If you did `XINT (X, 0)', you would get the address of the
-expression operand but cast as an integer; that might occasionally be
-useful, but it would be cleaner to write `(int) XEXP (X, 0)'. `XEXP
-(X, 1)' would also compile without error, and would return the second,
-integer operand cast as an expression pointer, which would probably
-result in a crash when accessed. Nothing stops you from writing `XEXP
-(X, 28)' either, but this will access memory past the end of the
-expression with unpredictable results.
-
- Access to operands which are vectors is more complicated. You can
-use the macro `XVEC' to get the vector-pointer itself, or the macros
-`XVECEXP' and `XVECLEN' to access the elements and length of a vector.
-
-`XVEC (EXP, IDX)'
- Access the vector-pointer which is operand number IDX in EXP.
-
-`XVECLEN (EXP, IDX)'
- Access the length (number of elements) in the vector which is in
- operand number IDX in EXP. This value is an `int'.
-
-`XVECEXP (EXP, IDX, ELTNUM)'
- Access element number ELTNUM in the vector which is in operand
- number IDX in EXP. This value is an RTX.
-
- It is up to you to make sure that ELTNUM is not negative and is
- less than `XVECLEN (EXP, IDX)'.
-
- All the macros defined in this section expand into lvalues and
-therefore can be used to assign the operands, lengths and vector
-elements as well as to access them.
-
-\1f
-File: gccint.info, Node: Flags, Next: Machine Modes, Prev: Accessors, Up: RTL
-
-Flags in an RTL Expression
-==========================
-
- RTL expressions contain several flags (one-bit bit-fields) that are
-used in certain types of expression. Most often they are accessed with
-the following macros, which expand into lvalues:
-
-`CONSTANT_POOL_ADDRESS_P (X)'
- Nonzero in a `symbol_ref' if it refers to part of the current
- function's constant pool. For most targets these addresses are in
- a `.rodata' section entirely separate from the function, but for
- some targets the addresses are close to the beginning of the
- function. In either case GCC assumes these addresses can be
- addressed directly, perhaps with the help of base registers.
- Stored in the `unchanging' field and printed as `/u'.
-
-`CONST_OR_PURE_CALL_P (X)'
- In a `call_insn', `note', or an `expr_list' for notes, indicates
- that the insn represents a call to a const or pure function.
- Stored in the `unchanging' field and printed as `/u'.
-
-`INSN_ANNULLED_BRANCH_P (X)'
- In an `insn' in the delay slot of a branch insn, indicates that an
- annulling branch should be used. See the discussion under
- `sequence' below. Stored in the `unchanging' field and printed as
- `/u'.
-
-`INSN_DEAD_CODE_P (X)'
- In an `insn' during the dead-code elimination pass, nonzero if the
- insn is dead. Stored in the `in_struct' field and printed as `/s'.
-
-`INSN_DELETED_P (X)'
- In an `insn', nonzero if the insn has been deleted. Stored in the
- `volatil' field and printed as `/v'.
-
-`INSN_FROM_TARGET_P (X)'
- In an `insn' in a delay slot of a branch, indicates that the insn
- is from the target of the branch. If the branch insn has
- `INSN_ANNULLED_BRANCH_P' set, this insn will only be executed if
- the branch is taken. For annulled branches with
- `INSN_FROM_TARGET_P' clear, the insn will be executed only if the
- branch is not taken. When `INSN_ANNULLED_BRANCH_P' is not set,
- this insn will always be executed. Stored in the `in_struct'
- field and printed as `/s'.
-
-`LABEL_OUTSIDE_LOOP_P (X)'
- In `label_ref' expressions, nonzero if this is a reference to a
- label that is outside the innermost loop containing the reference
- to the label. Stored in the `in_struct' field and printed as `/s'.
-
-`LABEL_PRESERVE_P (X)'
- In a `code_label', indicates that the label is referenced by code
- or data not visible to the RTL of a given function. Labels
- referenced by a non-local goto will have this bit set. Stored in
- the `in_struct' field and printed as `/s'.
-
-`LABEL_REF_NONLOCAL_P (X)'
- In `label_ref' and `reg_label' expressions, nonzero if this is a
- reference to a non-local label. Stored in the `volatil' field and
- printed as `/v'.
-
-`LINK_COST_FREE (X)'
- In the `LOG_LINKS' `insn_list' during scheduling, nonzero when the
- cost of executing an instruction through the link is zero, i.e.,
- the link makes the cost free. Stored in the `call' field and
- printed as `/c'.
-
-`LINK_COST_ZERO (X)'
- In the `LOG_LINKS' `insn_list' during scheduling, nonzero when the
- cost of executing an instruction through the link varies and is
- unchanged, i.e., the link has zero additional cost. Stored in the
- `jump' field and printed as `/j'.
-
-`MEM_IN_STRUCT_P (X)'
- In `mem' expressions, nonzero for reference to an entire structure,
- union or array, or to a component of one. Zero for references to a
- scalar variable or through a pointer to a scalar. If both this
- flag and `MEM_SCALAR_P' are clear, then we don't know whether this
- `mem' is in a structure or not. Both flags should never be
- simultaneously set. Stored in the `in_struct' field and printed
- as `/s'.
-
-`MEM_KEEP_ALIAS_SET_P (X)'
- In `mem' expressions, 1 if we should keep the alias set for this
- mem unchanged when we access a component. Set to 1, for example,
- when we are already in a non-addressable component of an aggregate.
- Stored in the `jump' field and printed as `/j'.
-
-`MEM_SCALAR_P (X)'
- In `mem' expressions, nonzero for reference to a scalar known not
- to be a member of a structure, union, or array. Zero for such
- references and for indirections through pointers, even pointers
- pointing to scalar types. If both this flag and `MEM_IN_STRUCT_P'
- are clear, then we don't know whether this `mem' is in a structure
- or not. Both flags should never be simultaneously set. Stored in
- the `frame_related' field and printed as `/f'.
-
-`MEM_VOLATILE_P (X)'
- In `mem' and `asm_operands' expressions, nonzero for volatile
- memory references. Stored in the `volatil' field and printed as
- `/v'.
-
-`REG_FUNCTION_VALUE_P (X)'
- Nonzero in a `reg' if it is the place in which this function's
- value is going to be returned. (This happens only in a hard
- register.) Stored in the `integrated' field and printed as `/i'.
-
-`REG_LOOP_TEST_P (X)'
- In `reg' expressions, nonzero if this register's entire life is
- contained in the exit test code for some loop. Stored in the
- `in_struct' field and printed as `/s'.
-
-`REG_POINTER (X)'
- Nonzero in a `reg' if the register holds a pointer. Stored in the
- `frame_related' field and printed as `/f'.
-
-`REG_USERVAR_P (X)'
- In a `reg', nonzero if it corresponds to a variable present in the
- user's source code. Zero for temporaries generated internally by
- the compiler. Stored in the `volatil' field and printed as `/v'.
-
- The same hard register may be used also for collecting the values
- of functions called by this one, but `REG_FUNCTION_VALUE_P' is zero
- in this kind of use.
-
-`RTX_FRAME_RELATED_P (X)'
- Nonzero in an `insn' or `set' which is part of a function prologue
- and sets the stack pointer, sets the frame pointer, or saves a
- register. This flag should also be set on an instruction that
- sets up a temporary register to use in place of the frame pointer.
- Stored in the `frame_related' field and printed as `/f'.
-
- In particular, on RISC targets where there are limits on the sizes
- of immediate constants, it is sometimes impossible to reach the
- register save area directly from the stack pointer. In that case,
- a temporary register is used that is near enough to the register
- save area, and the Canonical Frame Address, i.e., DWARF2's logical
- frame pointer, register must (temporarily) be changed to be this
- temporary register. So, the instruction that sets this temporary
- register must be marked as `RTX_FRAME_RELATED_P'.
-
- If the marked instruction is overly complex (defined in terms of
- what `dwarf2out_frame_debug_expr' can handle), you will also have
- to create a `REG_FRAME_RELATED_EXPR' note and attach it to the
- instruction. This note should contain a simple expression of the
- computation performed by this instruction, i.e., one that
- `dwarf2out_frame_debug_expr' can handle.
-
- This flag is required for exception handling support on targets
- with RTL prologues.
-
-`RTX_INTEGRATED_P (X)'
- Nonzero in an `insn', `insn_list', or `const' if it resulted from
- an in-line function call. Stored in the `integrated' field and
- printed as `/i'.
-
-`RTX_UNCHANGING_P (X)'
- Nonzero in a `reg' or `mem' if the memory is set at most once,
- anywhere. This does not mean that it is function invariant.
- Stored in the `unchanging' field and printed as `/u'.
-
-`SCHED_GROUP_P (X)'
- During instruction scheduling, in an `insn', indicates that the
- previous insn must be scheduled together with this insn. This is
- used to ensure that certain groups of instructions will not be
- split up by the instruction scheduling pass, for example, `use'
- insns before a `call_insn' may not be separated from the
- `call_insn'. Stored in the `in_struct' field and printed as `/s'.
-
-`SET_IS_RETURN_P (X)'
- For a `set', nonzero if it is for a return. Stored in the `jump'
- field and printed as `/j'.
-
-`SIBLING_CALL_P (X)'
- For a `call_insn', nonzero if the insn is a sibling call. Stored
- in the `jump' field and printed as `/j'.
-
-`STRING_POOL_ADDRESS_P (X)'
- For a `symbol_ref' expression, nonzero if it addresses this
- function's string constant pool. Stored in the `frame_related'
- field and printed as `/f'.
-
-`SUBREG_PROMOTED_UNSIGNED_P (X)'
- Nonzero in a `subreg' that has `SUBREG_PROMOTED_VAR_P' nonzero if
- the object being referenced is kept zero-extended and zero if it
- is kept sign-extended. Stored in the `unchanging' field and
- printed as `/u'.
-
-`SUBREG_PROMOTED_VAR_P (X)'
- Nonzero in a `subreg' if it was made when accessing an object that
- was promoted to a wider mode in accord with the `PROMOTED_MODE'
- machine description macro (*note Storage Layout::). In this case,
- the mode of the `subreg' is the declared mode of the object and
- the mode of `SUBREG_REG' is the mode of the register that holds
- the object. Promoted variables are always either sign- or
- zero-extended to the wider mode on every assignment. Stored in
- the `in_struct' field and printed as `/s'.
-
-`SYMBOL_REF_FLAG (X)'
- In a `symbol_ref', this is used as a flag for machine-specific
- purposes. Stored in the `volatil' field and printed as `/v'.
-
-`SYMBOL_REF_USED (X)'
- In a `symbol_ref', indicates that X has been used. This is
- normally only used to ensure that X is only declared external
- once. Stored in the `used' field.
-
-`SYMBOL_REF_WEAK (X)'
- In a `symbol_ref', indicates that X has been declared weak.
- Stored in the `integrated' field and printed as `/i'.
-
- These are the fields to which the above macros refer:
-
-`call'
- In the `LOG_LINKS' of an `insn_list' during scheduling, 1 means
- that the cost of executing an instruction through the link is zero.
-
- In an RTL dump, this flag is represented as `/c'.
-
-`frame_related'
- In an `insn' or `set' expression, 1 means that it is part of a
- function prologue and sets the stack pointer, sets the frame
- pointer, saves a register, or sets up a temporary register to use
- in place of the frame pointer.
-
- In `reg' expressions, 1 means that the register holds a pointer.
-
- In `symbol_ref' expressions, 1 means that the reference addresses
- this function's string constant pool.
-
- In `mem' expressions, 1 means that the reference is to a scalar.
-
- In an RTL dump, this flag is represented as `/f'.
-
-`in_struct'
- In `mem' expressions, it is 1 if the memory datum referred to is
- all or part of a structure or array; 0 if it is (or might be) a
- scalar variable. A reference through a C pointer has 0 because
- the pointer might point to a scalar variable. This information
- allows the compiler to determine something about possible cases of
- aliasing.
-
- In `reg' expressions, it is 1 if the register has its entire life
- contained within the test expression of some loop.
-
- In `subreg' expressions, 1 means that the `subreg' is accessing an
- object that has had its mode promoted from a wider mode.
-
- In `label_ref' expressions, 1 means that the referenced label is
- outside the innermost loop containing the insn in which the
- `label_ref' was found.
-
- In `code_label' expressions, it is 1 if the label may never be
- deleted. This is used for labels which are the target of
- non-local gotos. Such a label that would have been deleted is
- replaced with a `note' of type `NOTE_INSN_DELETED_LABEL'.
-
- In an `insn' during dead-code elimination, 1 means that the insn is
- dead code.
-
- In an `insn' during reorg for an insn in the delay slot of a
- branch, 1 means that this insn is from the target of the branch.
-
- In an `insn' during instruction scheduling, 1 means that this insn
- must be scheduled as part of a group together with the previous
- insn.
-
- In an RTL dump, this flag is represented as `/s'.
-
-`integrated'
- In an `insn', `insn_list', or `const', 1 means the RTL was
- produced by procedure integration.
-
- In `reg' expressions, 1 means the register contains the value to
- be returned by the current function. On machines that pass
- parameters in registers, the same register number may be used for
- parameters as well, but this flag is not set on such uses.
-
- In `symbol_ref' expressions, 1 means the referenced symbol is weak.
-
- In an RTL dump, this flag is represented as `/i'.
-
-`jump'
- In a `mem' expression, 1 means we should keep the alias set for
- this mem unchanged when we access a component.
-
- In a `set', 1 means it is for a return.
-
- In a `call_insn', 1 means it is a sibling call.
-
- In the `LOG_LINKS' of an `insn_list' during scheduling, 1 means the
- cost of executing an instruction through the link varies and is
- unchanging.
-
- In an RTL dump, this flag is represented as `/j'.
-
-`unchanging'
- In `reg' and `mem' expressions, 1 means that the value of the
- expression never changes.
-
- In `subreg' expressions, it is 1 if the `subreg' references an
- unsigned object whose mode has been promoted to a wider mode.
-
- In an `insn', 1 means that this is an annulling branch.
-
- In a `symbol_ref' expression, 1 means that this symbol addresses
- something in the per-function constant pool.
-
- In a `call_insn', `note', or an `expr_list' of notes, 1 means that
- this instruction is a call to a const or pure function.
-
- In an RTL dump, this flag is represented as `/u'.
-
-`used'
- This flag is used directly (without an access macro) at the end of
- RTL generation for a function, to count the number of times an
- expression appears in insns. Expressions that appear more than
- once are copied, according to the rules for shared structure
- (*note Sharing::).
-
- For a `reg', it is used directly (without an access macro) by the
- leaf register renumbering code to ensure that each register is only
- renumbered once.
-
- In a `symbol_ref', it indicates that an external declaration for
- the symbol has already been written.
-
-`volatil'
- In a `mem' or `asm_operands' expression, it is 1 if the memory
- reference is volatile. Volatile memory references may not be
- deleted, reordered or combined.
-
- In a `symbol_ref' expression, it is used for machine-specific
- purposes.
-
- In a `reg' expression, it is 1 if the value is a user-level
- variable. 0 indicates an internal compiler temporary.
-
- In an `insn', 1 means the insn has been deleted.
-
- In `label_ref' and `reg_label' expressions, 1 means a reference to
- a non-local label.
-
- In an RTL dump, this flag is represented as `/v'.
-
-\1f
-File: gccint.info, Node: Machine Modes, Next: Constants, Prev: Flags, Up: RTL
-
-Machine Modes
-=============
-
- A machine mode describes a size of data object and the
-representation used for it. In the C code, machine modes are
-represented by an enumeration type, `enum machine_mode', defined in
-`machmode.def'. Each RTL expression has room for a machine mode and so
-do certain kinds of tree expressions (declarations and types, to be
-precise).
-
- In debugging dumps and machine descriptions, the machine mode of an
-RTL expression is written after the expression code with a colon to
-separate them. The letters `mode' which appear at the end of each
-machine mode name are omitted. For example, `(reg:SI 38)' is a `reg'
-expression with machine mode `SImode'. If the mode is `VOIDmode', it
-is not written at all.
-
- Here is a table of machine modes. The term "byte" below refers to an
-object of `BITS_PER_UNIT' bits (*note Storage Layout::).
-
-`BImode'
- "Bit" mode represents a single bit, for predicate registers.
-
-`QImode'
- "Quarter-Integer" mode represents a single byte treated as an
- integer.
-
-`HImode'
- "Half-Integer" mode represents a two-byte integer.
-
-`PSImode'
- "Partial Single Integer" mode represents an integer which occupies
- four bytes but which doesn't really use all four. On some
- machines, this is the right mode to use for pointers.
-
-`SImode'
- "Single Integer" mode represents a four-byte integer.
-
-`PDImode'
- "Partial Double Integer" mode represents an integer which occupies
- eight bytes but which doesn't really use all eight. On some
- machines, this is the right mode to use for certain pointers.
-
-`DImode'
- "Double Integer" mode represents an eight-byte integer.
-
-`TImode'
- "Tetra Integer" (?) mode represents a sixteen-byte integer.
-
-`OImode'
- "Octa Integer" (?) mode represents a thirty-two-byte integer.
-
-`QFmode'
- "Quarter-Floating" mode represents a quarter-precision (single
- byte) floating point number.
-
-`HFmode'
- "Half-Floating" mode represents a half-precision (two byte)
- floating point number.
-
-`TQFmode'
- "Three-Quarter-Floating" (?) mode represents a
- three-quarter-precision (three byte) floating point number.
-
-`SFmode'
- "Single Floating" mode represents a four byte floating point
- number. In the common case, of a processor with IEEE arithmetic
- and 8-bit bytes, this is a single-precision IEEE floating point
- number; it can also be used for double-precision (on processors
- with 16-bit bytes) and single-precision VAX and IBM types.
-
-`DFmode'
- "Double Floating" mode represents an eight byte floating point
- number. In the common case, of a processor with IEEE arithmetic
- and 8-bit bytes, this is a double-precision IEEE floating point
- number.
-
-`XFmode'
- "Extended Floating" mode represents a twelve byte floating point
- number. This mode is used for IEEE extended floating point. On
- some systems not all bits within these bytes will actually be used.
-
-`TFmode'
- "Tetra Floating" mode represents a sixteen byte floating point
- number. This gets used for both the 96-bit extended IEEE
- floating-point types padded to 128 bits, and true 128-bit extended
- IEEE floating-point types.
-
-`CCmode'
- "Condition Code" mode represents the value of a condition code,
- which is a machine-specific set of bits used to represent the
- result of a comparison operation. Other machine-specific modes
- may also be used for the condition code. These modes are not used
- on machines that use `cc0' (see *note Condition Code::).
-
-`BLKmode'
- "Block" mode represents values that are aggregates to which none of
- the other modes apply. In RTL, only memory references can have
- this mode, and only if they appear in string-move or vector
- instructions. On machines which have no such instructions,
- `BLKmode' will not appear in RTL.
-
-`VOIDmode'
- Void mode means the absence of a mode or an unspecified mode. For
- example, RTL expressions of code `const_int' have mode `VOIDmode'
- because they can be taken to have whatever mode the context
- requires. In debugging dumps of RTL, `VOIDmode' is expressed by
- the absence of any mode.
-
-`QCmode, HCmode, SCmode, DCmode, XCmode, TCmode'
- These modes stand for a complex number represented as a pair of
- floating point values. The floating point values are in `QFmode',
- `HFmode', `SFmode', `DFmode', `XFmode', and `TFmode', respectively.
-
-`CQImode, CHImode, CSImode, CDImode, CTImode, COImode'
- These modes stand for a complex number represented as a pair of
- integer values. The integer values are in `QImode', `HImode',
- `SImode', `DImode', `TImode', and `OImode', respectively.
-
- The machine description defines `Pmode' as a C macro which expands
-into the machine mode used for addresses. Normally this is the mode
-whose size is `BITS_PER_WORD', `SImode' on 32-bit machines.
-
- The only modes which a machine description must support are
-`QImode', and the modes corresponding to `BITS_PER_WORD',
-`FLOAT_TYPE_SIZE' and `DOUBLE_TYPE_SIZE'. The compiler will attempt to
-use `DImode' for 8-byte structures and unions, but this can be
-prevented by overriding the definition of `MAX_FIXED_MODE_SIZE'.
-Alternatively, you can have the compiler use `TImode' for 16-byte
-structures and unions. Likewise, you can arrange for the C type `short
-int' to avoid using `HImode'.
-
- Very few explicit references to machine modes remain in the compiler
-and these few references will soon be removed. Instead, the machine
-modes are divided into mode classes. These are represented by the
-enumeration type `enum mode_class' defined in `machmode.h'. The
-possible mode classes are:
-
-`MODE_INT'
- Integer modes. By default these are `BImode', `QImode', `HImode',
- `SImode', `DImode', `TImode', and `OImode'.
-
-`MODE_PARTIAL_INT'
- The "partial integer" modes, `PQImode', `PHImode', `PSImode' and
- `PDImode'.
-
-`MODE_FLOAT'
- Floating point modes. By default these are `QFmode', `HFmode',
- `TQFmode', `SFmode', `DFmode', `XFmode' and `TFmode'.
-
-`MODE_COMPLEX_INT'
- Complex integer modes. (These are not currently implemented).
-
-`MODE_COMPLEX_FLOAT'
- Complex floating point modes. By default these are `QCmode',
- `HCmode', `SCmode', `DCmode', `XCmode', and `TCmode'.
-
-`MODE_FUNCTION'
- Algol or Pascal function variables including a static chain.
- (These are not currently implemented).
-
-`MODE_CC'
- Modes representing condition code values. These are `CCmode' plus
- any modes listed in the `EXTRA_CC_MODES' macro. *Note Jump
- Patterns::, also see *Note Condition Code::.
-
-`MODE_RANDOM'
- This is a catchall mode class for modes which don't fit into the
- above classes. Currently `VOIDmode' and `BLKmode' are in
- `MODE_RANDOM'.
-
- Here are some C macros that relate to machine modes:
-
-`GET_MODE (X)'
- Returns the machine mode of the RTX X.
-
-`PUT_MODE (X, NEWMODE)'
- Alters the machine mode of the RTX X to be NEWMODE.
-
-`NUM_MACHINE_MODES'
- Stands for the number of machine modes available on the target
- machine. This is one greater than the largest numeric value of any
- machine mode.
-
-`GET_MODE_NAME (M)'
- Returns the name of mode M as a string.
-
-`GET_MODE_CLASS (M)'
- Returns the mode class of mode M.
-
-`GET_MODE_WIDER_MODE (M)'
- Returns the next wider natural mode. For example, the expression
- `GET_MODE_WIDER_MODE (QImode)' returns `HImode'.
-
-`GET_MODE_SIZE (M)'
- Returns the size in bytes of a datum of mode M.
-
-`GET_MODE_BITSIZE (M)'
- Returns the size in bits of a datum of mode M.
-
-`GET_MODE_MASK (M)'
- Returns a bitmask containing 1 for all bits in a word that fit
- within mode M. This macro can only be used for modes whose
- bitsize is less than or equal to `HOST_BITS_PER_INT'.
-
-`GET_MODE_ALIGNMENT (M)'
- Return the required alignment, in bits, for an object of mode M.
-
-`GET_MODE_UNIT_SIZE (M)'
- Returns the size in bytes of the subunits of a datum of mode M.
- This is the same as `GET_MODE_SIZE' except in the case of complex
- modes. For them, the unit size is the size of the real or
- imaginary part.
-
-`GET_MODE_NUNITS (M)'
- Returns the number of units contained in a mode, i.e.,
- `GET_MODE_SIZE' divided by `GET_MODE_UNIT_SIZE'.
-
-`GET_CLASS_NARROWEST_MODE (C)'
- Returns the narrowest mode in mode class C.
-
- The global variables `byte_mode' and `word_mode' contain modes whose
-classes are `MODE_INT' and whose bitsizes are either `BITS_PER_UNIT' or
-`BITS_PER_WORD', respectively. On 32-bit machines, these are `QImode'
-and `SImode', respectively.
-
-\1f
-File: gccint.info, Node: Constants, Next: Regs and Memory, Prev: Machine Modes, Up: RTL
-
-Constant Expression Types
-=========================
-
- The simplest RTL expressions are those that represent constant
-values.
-
-`(const_int I)'
- This type of expression represents the integer value I. I is
- customarily accessed with the macro `INTVAL' as in `INTVAL (EXP)',
- which is equivalent to `XWINT (EXP, 0)'.
-
- There is only one expression object for the integer value zero; it
- is the value of the variable `const0_rtx'. Likewise, the only
- expression for integer value one is found in `const1_rtx', the only
- expression for integer value two is found in `const2_rtx', and the
- only expression for integer value negative one is found in
- `constm1_rtx'. Any attempt to create an expression of code
- `const_int' and value zero, one, two or negative one will return
- `const0_rtx', `const1_rtx', `const2_rtx' or `constm1_rtx' as
- appropriate.
-
- Similarly, there is only one object for the integer whose value is
- `STORE_FLAG_VALUE'. It is found in `const_true_rtx'. If
- `STORE_FLAG_VALUE' is one, `const_true_rtx' and `const1_rtx' will
- point to the same object. If `STORE_FLAG_VALUE' is -1,
- `const_true_rtx' and `constm1_rtx' will point to the same object.
-
-`(const_double:M ADDR I0 I1 ...)'
- Represents either a floating-point constant of mode M or an
- integer constant too large to fit into `HOST_BITS_PER_WIDE_INT'
- bits but small enough to fit within twice that number of bits (GCC
- does not provide a mechanism to represent even larger constants).
- In the latter case, M will be `VOIDmode'.
-
-`(const_vector:M [X0 X1 ...])'
- Represents a vector constant. The square brackets stand for the
- vector containing the constant elements. X0, X1 and so on are the
- `const_int' or `const_double' elements.
-
- The number of units in a `const_vector' is obtained with the macro
- `CONST_VECTOR_NUNITS' as in `CONST_VECTOR_NUNITS (V)'.
-
- Individual elements in a vector constant are accessed with the
- macro `CONST_VECTOR_ELT' as in `CONST_VECTOR_ELT (V, N)' where V
- is the vector constant and N is the element desired.
-
- ADDR is used to contain the `mem' expression that corresponds to
- the location in memory that at which the constant can be found. If
- it has not been allocated a memory location, but is on the chain
- of all `const_double' expressions in this compilation (maintained
- using an undisplayed field), ADDR contains `const0_rtx'. If it is
- not on the chain, ADDR contains `cc0_rtx'. ADDR is customarily
- accessed with the macro `CONST_DOUBLE_MEM' and the chain field via
- `CONST_DOUBLE_CHAIN'.
-
- If M is `VOIDmode', the bits of the value are stored in I0 and I1.
- I0 is customarily accessed with the macro `CONST_DOUBLE_LOW' and
- I1 with `CONST_DOUBLE_HIGH'.
-
- If the constant is floating point (regardless of its precision),
- then the number of integers used to store the value depends on the
- size of `REAL_VALUE_TYPE' (*note Cross-compilation::). The
- integers represent a floating point number, but not precisely in
- the target machine's or host machine's floating point format. To
- convert them to the precise bit pattern used by the target
- machine, use the macro `REAL_VALUE_TO_TARGET_DOUBLE' and friends
- (*note Data Output::).
-
- The macro `CONST0_RTX (MODE)' refers to an expression with value 0
- in mode MODE. If mode MODE is of mode class `MODE_INT', it
- returns `const0_rtx'. If mode MODE is of mode class `MODE_FLOAT',
- it returns a `CONST_DOUBLE' expression in mode MODE. Otherwise,
- it returns a `CONST_VECTOR' expression in mode MODE. Similarly,
- the macro `CONST1_RTX (MODE)' refers to an expression with value 1
- in mode MODE and similarly for `CONST2_RTX'. The `CONST1_RTX' and
- `CONST2_RTX' macros are undefined for vector modes.
-
-`(const_string STR)'
- Represents a constant string with value STR. Currently this is
- used only for insn attributes (*note Insn Attributes::) since
- constant strings in C are placed in memory.
-
-`(symbol_ref:MODE SYMBOL)'
- Represents the value of an assembler label for data. SYMBOL is a
- string that describes the name of the assembler label. If it
- starts with a `*', the label is the rest of SYMBOL not including
- the `*'. Otherwise, the label is SYMBOL, usually prefixed with
- `_'.
-
- The `symbol_ref' contains a mode, which is usually `Pmode'.
- Usually that is the only mode for which a symbol is directly valid.
-
-`(label_ref LABEL)'
- Represents the value of an assembler label for code. It contains
- one operand, an expression, which must be a `code_label' or a
- `note' of type `NOTE_INSN_DELETED_LABEL' that appears in the
- instruction sequence to identify the place where the label should
- go.
-
- The reason for using a distinct expression type for code label
- references is so that jump optimization can distinguish them.
-
-`(const:M EXP)'
- Represents a constant that is the result of an assembly-time
- arithmetic computation. The operand, EXP, is an expression that
- contains only constants (`const_int', `symbol_ref' and `label_ref'
- expressions) combined with `plus' and `minus'. However, not all
- combinations are valid, since the assembler cannot do arbitrary
- arithmetic on relocatable symbols.
-
- M should be `Pmode'.
-
-`(high:M EXP)'
- Represents the high-order bits of EXP, usually a `symbol_ref'.
- The number of bits is machine-dependent and is normally the number
- of bits specified in an instruction that initializes the high
- order bits of a register. It is used with `lo_sum' to represent
- the typical two-instruction sequence used in RISC machines to
- reference a global memory location.
-
- M should be `Pmode'.
-
-\1f
-File: gccint.info, Node: Regs and Memory, Next: Arithmetic, Prev: Constants, Up: RTL
-
-Registers and Memory
-====================
-
- Here are the RTL expression types for describing access to machine
-registers and to main memory.
-
-`(reg:M N)'
- For small values of the integer N (those that are less than
- `FIRST_PSEUDO_REGISTER'), this stands for a reference to machine
- register number N: a "hard register". For larger values of N, it
- stands for a temporary value or "pseudo register". The compiler's
- strategy is to generate code assuming an unlimited number of such
- pseudo registers, and later convert them into hard registers or
- into memory references.
-
- M is the machine mode of the reference. It is necessary because
- machines can generally refer to each register in more than one
- mode. For example, a register may contain a full word but there
- may be instructions to refer to it as a half word or as a single
- byte, as well as instructions to refer to it as a floating point
- number of various precisions.
-
- Even for a register that the machine can access in only one mode,
- the mode must always be specified.
-
- The symbol `FIRST_PSEUDO_REGISTER' is defined by the machine
- description, since the number of hard registers on the machine is
- an invariant characteristic of the machine. Note, however, that
- not all of the machine registers must be general registers. All
- the machine registers that can be used for storage of data are
- given hard register numbers, even those that can be used only in
- certain instructions or can hold only certain types of data.
-
- A hard register may be accessed in various modes throughout one
- function, but each pseudo register is given a natural mode and is
- accessed only in that mode. When it is necessary to describe an
- access to a pseudo register using a nonnatural mode, a `subreg'
- expression is used.
-
- A `reg' expression with a machine mode that specifies more than
- one word of data may actually stand for several consecutive
- registers. If in addition the register number specifies a
- hardware register, then it actually represents several consecutive
- hardware registers starting with the specified one.
-
- Each pseudo register number used in a function's RTL code is
- represented by a unique `reg' expression.
-
- Some pseudo register numbers, those within the range of
- `FIRST_VIRTUAL_REGISTER' to `LAST_VIRTUAL_REGISTER' only appear
- during the RTL generation phase and are eliminated before the
- optimization phases. These represent locations in the stack frame
- that cannot be determined until RTL generation for the function
- has been completed. The following virtual register numbers are
- defined:
-
- `VIRTUAL_INCOMING_ARGS_REGNUM'
- This points to the first word of the incoming arguments
- passed on the stack. Normally these arguments are placed
- there by the caller, but the callee may have pushed some
- arguments that were previously passed in registers.
-
- When RTL generation is complete, this virtual register is
- replaced by the sum of the register given by
- `ARG_POINTER_REGNUM' and the value of `FIRST_PARM_OFFSET'.
-
- `VIRTUAL_STACK_VARS_REGNUM'
- If `FRAME_GROWS_DOWNWARD' is defined, this points to
- immediately above the first variable on the stack.
- Otherwise, it points to the first variable on the stack.
-
- `VIRTUAL_STACK_VARS_REGNUM' is replaced with the sum of the
- register given by `FRAME_POINTER_REGNUM' and the value
- `STARTING_FRAME_OFFSET'.
-
- `VIRTUAL_STACK_DYNAMIC_REGNUM'
- This points to the location of dynamically allocated memory
- on the stack immediately after the stack pointer has been
- adjusted by the amount of memory desired.
-
- This virtual register is replaced by the sum of the register
- given by `STACK_POINTER_REGNUM' and the value
- `STACK_DYNAMIC_OFFSET'.
-
- `VIRTUAL_OUTGOING_ARGS_REGNUM'
- This points to the location in the stack at which outgoing
- arguments should be written when the stack is pre-pushed
- (arguments pushed using push insns should always use
- `STACK_POINTER_REGNUM').
-
- This virtual register is replaced by the sum of the register
- given by `STACK_POINTER_REGNUM' and the value
- `STACK_POINTER_OFFSET'.
-
-`(subreg:M REG BYTENUM)'
- `subreg' expressions are used to refer to a register in a machine
- mode other than its natural one, or to refer to one register of a
- multi-part `reg' that actually refers to several registers.
-
- Each pseudo-register has a natural mode. If it is necessary to
- operate on it in a different mode--for example, to perform a
- fullword move instruction on a pseudo-register that contains a
- single byte--the pseudo-register must be enclosed in a `subreg'.
- In such a case, BYTENUM is zero.
-
- Usually M is at least as narrow as the mode of REG, in which case
- it is restricting consideration to only the bits of REG that are
- in M.
-
- Sometimes M is wider than the mode of REG. These `subreg'
- expressions are often called "paradoxical". They are used in
- cases where we want to refer to an object in a wider mode but do
- not care what value the additional bits have. The reload pass
- ensures that paradoxical references are only made to hard
- registers.
-
- The other use of `subreg' is to extract the individual registers of
- a multi-register value. Machine modes such as `DImode' and
- `TImode' can indicate values longer than a word, values which
- usually require two or more consecutive registers. To access one
- of the registers, use a `subreg' with mode `SImode' and a BYTENUM
- offset that says which register.
-
- Storing in a non-paradoxical `subreg' has undefined results for
- bits belonging to the same word as the `subreg'. This laxity makes
- it easier to generate efficient code for such instructions. To
- represent an instruction that preserves all the bits outside of
- those in the `subreg', use `strict_low_part' around the `subreg'.
-
- The compilation parameter `WORDS_BIG_ENDIAN', if set to 1, says
- that byte number zero is part of the most significant word;
- otherwise, it is part of the least significant word.
-
- The compilation parameter `BYTES_BIG_ENDIAN', if set to 1, says
- that byte number zero is the most significant byte within a word;
- otherwise, it is the least significant byte within a word.
-
- On a few targets, `FLOAT_WORDS_BIG_ENDIAN' disagrees with
- `WORDS_BIG_ENDIAN'. However, most parts of the compiler treat
- floating point values as if they had the same endianness as
- integer values. This works because they handle them solely as a
- collection of integer values, with no particular numerical value.
- Only real.c and the runtime libraries care about
- `FLOAT_WORDS_BIG_ENDIAN'.
-
- Between the combiner pass and the reload pass, it is possible to
- have a paradoxical `subreg' which contains a `mem' instead of a
- `reg' as its first operand. After the reload pass, it is also
- possible to have a non-paradoxical `subreg' which contains a
- `mem'; this usually occurs when the `mem' is a stack slot which
- replaced a pseudo register.
-
- Note that it is not valid to access a `DFmode' value in `SFmode'
- using a `subreg'. On some machines the most significant part of a
- `DFmode' value does not have the same format as a single-precision
- floating value.
-
- It is also not valid to access a single word of a multi-word value
- in a hard register when less registers can hold the value than
- would be expected from its size. For example, some 32-bit
- machines have floating-point registers that can hold an entire
- `DFmode' value. If register 10 were such a register `(subreg:SI
- (reg:DF 10) 1)' would be invalid because there is no way to
- convert that reference to a single machine register. The reload
- pass prevents `subreg' expressions such as these from being formed.
-
- The first operand of a `subreg' expression is customarily accessed
- with the `SUBREG_REG' macro and the second operand is customarily
- accessed with the `SUBREG_BYTE' macro.
-
-`(scratch:M)'
- This represents a scratch register that will be required for the
- execution of a single instruction and not used subsequently. It is
- converted into a `reg' by either the local register allocator or
- the reload pass.
-
- `scratch' is usually present inside a `clobber' operation (*note
- Side Effects::).
-
-`(cc0)'
- This refers to the machine's condition code register. It has no
- operands and may not have a machine mode. There are two ways to
- use it:
-
- * To stand for a complete set of condition code flags. This is
- best on most machines, where each comparison sets the entire
- series of flags.
-
- With this technique, `(cc0)' may be validly used in only two
- contexts: as the destination of an assignment (in test and
- compare instructions) and in comparison operators comparing
- against zero (`const_int' with value zero; that is to say,
- `const0_rtx').
-
- * To stand for a single flag that is the result of a single
- condition. This is useful on machines that have only a
- single flag bit, and in which comparison instructions must
- specify the condition to test.
-
- With this technique, `(cc0)' may be validly used in only two
- contexts: as the destination of an assignment (in test and
- compare instructions) where the source is a comparison
- operator, and as the first operand of `if_then_else' (in a
- conditional branch).
-
- There is only one expression object of code `cc0'; it is the value
- of the variable `cc0_rtx'. Any attempt to create an expression of
- code `cc0' will return `cc0_rtx'.
-
- Instructions can set the condition code implicitly. On many
- machines, nearly all instructions set the condition code based on
- the value that they compute or store. It is not necessary to
- record these actions explicitly in the RTL because the machine
- description includes a prescription for recognizing the
- instructions that do so (by means of the macro
- `NOTICE_UPDATE_CC'). *Note Condition Code::. Only instructions
- whose sole purpose is to set the condition code, and instructions
- that use the condition code, need mention `(cc0)'.
-
- On some machines, the condition code register is given a register
- number and a `reg' is used instead of `(cc0)'. This is usually the
- preferable approach if only a small subset of instructions modify
- the condition code. Other machines store condition codes in
- general registers; in such cases a pseudo register should be used.
-
- Some machines, such as the Sparc and RS/6000, have two sets of
- arithmetic instructions, one that sets and one that does not set
- the condition code. This is best handled by normally generating
- the instruction that does not set the condition code, and making a
- pattern that both performs the arithmetic and sets the condition
- code register (which would not be `(cc0)' in this case). For
- examples, search for `addcc' and `andcc' in `sparc.md'.
-
-`(pc)'
- This represents the machine's program counter. It has no operands
- and may not have a machine mode. `(pc)' may be validly used only
- in certain specific contexts in jump instructions.
-
- There is only one expression object of code `pc'; it is the value
- of the variable `pc_rtx'. Any attempt to create an expression of
- code `pc' will return `pc_rtx'.
-
- All instructions that do not jump alter the program counter
- implicitly by incrementing it, but there is no need to mention
- this in the RTL.
-
-`(mem:M ADDR ALIAS)'
- This RTX represents a reference to main memory at an address
- represented by the expression ADDR. M specifies how large a unit
- of memory is accessed. ALIAS specifies an alias set for the
- reference. In general two items are in different alias sets if
- they cannot reference the same memory address.
-
-`(addressof:M REG)'
- This RTX represents a request for the address of register REG.
- Its mode is always `Pmode'. If there are any `addressof'
- expressions left in the function after CSE, REG is forced into the
- stack and the `addressof' expression is replaced with a `plus'
- expression for the address of its stack slot.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Arithmetic, Next: Comparisons, Prev: Regs and Memory, Up: RTL
-
-RTL Expressions for Arithmetic
-==============================
-
- Unless otherwise specified, all the operands of arithmetic
-expressions must be valid for mode M. An operand is valid for mode M
-if it has mode M, or if it is a `const_int' or `const_double' and M is
-a mode of class `MODE_INT'.
-
- For commutative binary operations, constants should be placed in the
-second operand.
-
-`(plus:M X Y)'
- Represents the sum of the values represented by X and Y carried
- out in machine mode M.
-
-`(lo_sum:M X Y)'
- Like `plus', except that it represents that sum of X and the
- low-order bits of Y. The number of low order bits is
- machine-dependent but is normally the number of bits in a `Pmode'
- item minus the number of bits set by the `high' code (*note
- Constants::).
-
- M should be `Pmode'.
-
-`(minus:M X Y)'
- Like `plus' but represents subtraction.
-
-`(ss_plus:M X Y)'
- Like `plus', but using signed saturation in case of an overflow.
-
-`(us_plus:M X Y)'
- Like `plus', but using unsigned saturation in case of an overflow.
-
-`(ss_minus:M X Y)'
- Like `minus', but using signed saturation in case of an overflow.
-
-`(us_minus:M X Y)'
- Like `minus', but using unsigned saturation in case of an overflow.
-
-`(compare:M X Y)'
- Represents the result of subtracting Y from X for purposes of
- comparison. The result is computed without overflow, as if with
- infinite precision.
-
- Of course, machines can't really subtract with infinite precision.
- However, they can pretend to do so when only the sign of the
- result will be used, which is the case when the result is stored
- in the condition code. And that is the _only_ way this kind of
- expression may validly be used: as a value to be stored in the
- condition codes, either `(cc0)' or a register. *Note
- Comparisons::.
-
- The mode M is not related to the modes of X and Y, but instead is
- the mode of the condition code value. If `(cc0)' is used, it is
- `VOIDmode'. Otherwise it is some mode in class `MODE_CC', often
- `CCmode'. *Note Condition Code::. If M is `VOIDmode' or
- `CCmode', the operation returns sufficient information (in an
- unspecified format) so that any comparison operator can be applied
- to the result of the `COMPARE' operation. For other modes in
- class `MODE_CC', the operation only returns a subset of this
- information.
-
- Normally, X and Y must have the same mode. Otherwise, `compare'
- is valid only if the mode of X is in class `MODE_INT' and Y is a
- `const_int' or `const_double' with mode `VOIDmode'. The mode of X
- determines what mode the comparison is to be done in; thus it must
- not be `VOIDmode'.
-
- If one of the operands is a constant, it should be placed in the
- second operand and the comparison code adjusted as appropriate.
-
- A `compare' specifying two `VOIDmode' constants is not valid since
- there is no way to know in what mode the comparison is to be
- performed; the comparison must either be folded during the
- compilation or the first operand must be loaded into a register
- while its mode is still known.
-
-`(neg:M X)'
- Represents the negation (subtraction from zero) of the value
- represented by X, carried out in mode M.
-
-`(mult:M X Y)'
- Represents the signed product of the values represented by X and Y
- carried out in machine mode M.
-
- Some machines support a multiplication that generates a product
- wider than the operands. Write the pattern for this as
-
- (mult:M (sign_extend:M X) (sign_extend:M Y))
-
- where M is wider than the modes of X and Y, which need not be the
- same.
-
- For unsigned widening multiplication, use the same idiom, but with
- `zero_extend' instead of `sign_extend'.
-
-`(div:M X Y)'
- Represents the quotient in signed division of X by Y, carried out
- in machine mode M. If M is a floating point mode, it represents
- the exact quotient; otherwise, the integerized quotient.
-
- Some machines have division instructions in which the operands and
- quotient widths are not all the same; you should represent such
- instructions using `truncate' and `sign_extend' as in,
-
- (truncate:M1 (div:M2 X (sign_extend:M2 Y)))
-
-`(udiv:M X Y)'
- Like `div' but represents unsigned division.
-
-`(mod:M X Y)'
-`(umod:M X Y)'
- Like `div' and `udiv' but represent the remainder instead of the
- quotient.
-
-`(smin:M X Y)'
-`(smax:M X Y)'
- Represents the smaller (for `smin') or larger (for `smax') of X
- and Y, interpreted as signed integers in mode M.
-
-`(umin:M X Y)'
-`(umax:M X Y)'
- Like `smin' and `smax', but the values are interpreted as unsigned
- integers.
-
-`(not:M X)'
- Represents the bitwise complement of the value represented by X,
- carried out in mode M, which must be a fixed-point machine mode.
-
-`(and:M X Y)'
- Represents the bitwise logical-and of the values represented by X
- and Y, carried out in machine mode M, which must be a fixed-point
- machine mode.
-
-`(ior:M X Y)'
- Represents the bitwise inclusive-or of the values represented by X
- and Y, carried out in machine mode M, which must be a fixed-point
- mode.
-
-`(xor:M X Y)'
- Represents the bitwise exclusive-or of the values represented by X
- and Y, carried out in machine mode M, which must be a fixed-point
- mode.
-
-`(ashift:M X C)'
- Represents the result of arithmetically shifting X left by C
- places. X have mode M, a fixed-point machine mode. C be a
- fixed-point mode or be a constant with mode `VOIDmode'; which mode
- is determined by the mode called for in the machine description
- entry for the left-shift instruction. For example, on the VAX,
- the mode of C is `QImode' regardless of M.
-
-`(lshiftrt:M X C)'
-`(ashiftrt:M X C)'
- Like `ashift' but for right shift. Unlike the case for left shift,
- these two operations are distinct.
-
-`(rotate:M X C)'
-`(rotatert:M X C)'
- Similar but represent left and right rotate. If C is a constant,
- use `rotate'.
-
-`(abs:M X)'
- Represents the absolute value of X, computed in mode M.
-
-`(sqrt:M X)'
- Represents the square root of X, computed in mode M. Most often M
- will be a floating point mode.
-
-`(ffs:M X)'
- Represents one plus the index of the least significant 1-bit in X,
- represented as an integer of mode M. (The value is zero if X is
- zero.) The mode of X need not be M; depending on the target
- machine, various mode combinations may be valid.
-
-\1f
-File: gccint.info, Node: Comparisons, Next: Bit-Fields, Prev: Arithmetic, Up: RTL
-
-Comparison Operations
-=====================
-
- Comparison operators test a relation on two operands and are
-considered to represent a machine-dependent nonzero value described by,
-but not necessarily equal to, `STORE_FLAG_VALUE' (*note Misc::) if the
-relation holds, or zero if it does not. The mode of the comparison
-operation is independent of the mode of the data being compared. If
-the comparison operation is being tested (e.g., the first operand of an
-`if_then_else'), the mode must be `VOIDmode'. If the comparison
-operation is producing data to be stored in some variable, the mode
-must be in class `MODE_INT'. All comparison operations producing data
-must use the same mode, which is machine-specific.
-
- There are two ways that comparison operations may be used. The
-comparison operators may be used to compare the condition codes `(cc0)'
-against zero, as in `(eq (cc0) (const_int 0))'. Such a construct
-actually refers to the result of the preceding instruction in which the
-condition codes were set. The instruction setting the condition code
-must be adjacent to the instruction using the condition code; only
-`note' insns may separate them.
-
- Alternatively, a comparison operation may directly compare two data
-objects. The mode of the comparison is determined by the operands; they
-must both be valid for a common machine mode. A comparison with both
-operands constant would be invalid as the machine mode could not be
-deduced from it, but such a comparison should never exist in RTL due to
-constant folding.
-
- In the example above, if `(cc0)' were last set to `(compare X Y)',
-the comparison operation is identical to `(eq X Y)'. Usually only one
-style of comparisons is supported on a particular machine, but the
-combine pass will try to merge the operations to produce the `eq' shown
-in case it exists in the context of the particular insn involved.
-
- Inequality comparisons come in two flavors, signed and unsigned.
-Thus, there are distinct expression codes `gt' and `gtu' for signed and
-unsigned greater-than. These can produce different results for the same
-pair of integer values: for example, 1 is signed greater-than -1 but not
-unsigned greater-than, because -1 when regarded as unsigned is actually
-`0xffffffff' which is greater than 1.
-
- The signed comparisons are also used for floating point values.
-Floating point comparisons are distinguished by the machine modes of
-the operands.
-
-`(eq:M X Y)'
- `STORE_FLAG_VALUE' if the values represented by X and Y are equal,
- otherwise 0.
-
-`(ne:M X Y)'
- `STORE_FLAG_VALUE' if the values represented by X and Y are not
- equal, otherwise 0.
-
-`(gt:M X Y)'
- `STORE_FLAG_VALUE' if the X is greater than Y. If they are
- fixed-point, the comparison is done in a signed sense.
-
-`(gtu:M X Y)'
- Like `gt' but does unsigned comparison, on fixed-point numbers
- only.
-
-`(lt:M X Y)'
-`(ltu:M X Y)'
- Like `gt' and `gtu' but test for "less than".
-
-`(ge:M X Y)'
-`(geu:M X Y)'
- Like `gt' and `gtu' but test for "greater than or equal".
-
-`(le:M X Y)'
-`(leu:M X Y)'
- Like `gt' and `gtu' but test for "less than or equal".
-
-`(if_then_else COND THEN ELSE)'
- This is not a comparison operation but is listed here because it is
- always used in conjunction with a comparison operation. To be
- precise, COND is a comparison expression. This expression
- represents a choice, according to COND, between the value
- represented by THEN and the one represented by ELSE.
-
- On most machines, `if_then_else' expressions are valid only to
- express conditional jumps.
-
-`(cond [TEST1 VALUE1 TEST2 VALUE2 ...] DEFAULT)'
- Similar to `if_then_else', but more general. Each of TEST1,
- TEST2, ... is performed in turn. The result of this expression is
- the VALUE corresponding to the first nonzero test, or DEFAULT if
- none of the tests are nonzero expressions.
-
- This is currently not valid for instruction patterns and is
- supported only for insn attributes. *Note Insn Attributes::.
-
-\1f
-File: gccint.info, Node: Bit-Fields, Next: Vector Operations, Prev: Comparisons, Up: RTL
-
-Bit-Fields
-==========
-
- Special expression codes exist to represent bit-field instructions.
-These types of expressions are lvalues in RTL; they may appear on the
-left side of an assignment, indicating insertion of a value into the
-specified bit-field.
-
-`(sign_extract:M LOC SIZE POS)'
- This represents a reference to a sign-extended bit-field contained
- or starting in LOC (a memory or register reference). The bit-field
- is SIZE bits wide and starts at bit POS. The compilation option
- `BITS_BIG_ENDIAN' says which end of the memory unit POS counts
- from.
-
- If LOC is in memory, its mode must be a single-byte integer mode.
- If LOC is in a register, the mode to use is specified by the
- operand of the `insv' or `extv' pattern (*note Standard Names::)
- and is usually a full-word integer mode, which is the default if
- none is specified.
-
- The mode of POS is machine-specific and is also specified in the
- `insv' or `extv' pattern.
-
- The mode M is the same as the mode that would be used for LOC if
- it were a register.
-
-`(zero_extract:M LOC SIZE POS)'
- Like `sign_extract' but refers to an unsigned or zero-extended
- bit-field. The same sequence of bits are extracted, but they are
- filled to an entire word with zeros instead of by sign-extension.
-
-\1f
-File: gccint.info, Node: Vector Operations, Next: Conversions, Prev: Bit-Fields, Up: RTL
-
-Vector Operations
-=================
-
- All normal RTL expressions can be used with vector modes; they are
-interpreted as operating on each part of the vector independently.
-Additionally, there are a few new expressions to describe specific
-vector operations.
-
-`(vec_merge:M VEC1 VEC2 ITEMS)'
- This describes a merge operation between two vectors. The result
- is a vector of mode M; its elements are selected from either VEC1
- or VEC2. Which elements are selected is described by ITEMS, which
- is a bit mask represented by a `const_int'; a zero bit indicates
- the corresponding element in the result vector is taken from VEC2
- while a set bit indicates it is taken from VEC1.
-
-`(vec_select:M VEC1 SELECTION)'
- This describes an operation that selects parts of a vector. VEC1
- is the source vector, SELECTION is a `parallel' that contains a
- `const_int' for each of the subparts of the result vector, giving
- the number of the source subpart that should be stored into it.
-
-`(vec_concat:M VEC1 VEC2)'
- Describes a vector concat operation. The result is a
- concatenation of the vectors VEC1 and VEC2; its length is the sum
- of the lengths of the two inputs.
-
-`(vec_const:M SUBPARTS)'
- This describes a constant vector. SUBPARTS is a `parallel' that
- contains a constant for each of the subparts of the vector.
-
-`(vec_duplicate:M VEC)'
- This operation converts a small vector into a larger one by
- duplicating the input values. The output vector mode must have
- the same submodes as the input vector mode, and the number of
- output parts must be an integer multiple of the number of input
- parts.
-
-
-\1f
-File: gccint.info, Node: Conversions, Next: RTL Declarations, Prev: Vector Operations, Up: RTL
-
-Conversions
-===========
-
- All conversions between machine modes must be represented by
-explicit conversion operations. For example, an expression which is
-the sum of a byte and a full word cannot be written as `(plus:SI
-(reg:QI 34) (reg:SI 80))' because the `plus' operation requires two
-operands of the same machine mode. Therefore, the byte-sized operand
-is enclosed in a conversion operation, as in
-
- (plus:SI (sign_extend:SI (reg:QI 34)) (reg:SI 80))
-
- The conversion operation is not a mere placeholder, because there
-may be more than one way of converting from a given starting mode to
-the desired final mode. The conversion operation code says how to do
-it.
-
- For all conversion operations, X must not be `VOIDmode' because the
-mode in which to do the conversion would not be known. The conversion
-must either be done at compile-time or X must be placed into a register.
-
-`(sign_extend:M X)'
- Represents the result of sign-extending the value X to machine
- mode M. M must be a fixed-point mode and X a fixed-point value of
- a mode narrower than M.
-
-`(zero_extend:M X)'
- Represents the result of zero-extending the value X to machine
- mode M. M must be a fixed-point mode and X a fixed-point value of
- a mode narrower than M.
-
-`(float_extend:M X)'
- Represents the result of extending the value X to machine mode M.
- M must be a floating point mode and X a floating point value of a
- mode narrower than M.
-
-`(truncate:M X)'
- Represents the result of truncating the value X to machine mode M.
- M must be a fixed-point mode and X a fixed-point value of a mode
- wider than M.
-
-`(ss_truncate:M X)'
- Represents the result of truncating the value X to machine mode M,
- using signed saturation in the case of overflow. Both M and the
- mode of X must be fixed-point modes.
-
-`(us_truncate:M X)'
- Represents the result of truncating the value X to machine mode M,
- using unsigned saturation in the case of overflow. Both M and the
- mode of X must be fixed-point modes.
-
-`(float_truncate:M X)'
- Represents the result of truncating the value X to machine mode M.
- M must be a floating point mode and X a floating point value of a
- mode wider than M.
-
-`(float:M X)'
- Represents the result of converting fixed point value X, regarded
- as signed, to floating point mode M.
-
-`(unsigned_float:M X)'
- Represents the result of converting fixed point value X, regarded
- as unsigned, to floating point mode M.
-
-`(fix:M X)'
- When M is a fixed point mode, represents the result of converting
- floating point value X to mode M, regarded as signed. How
- rounding is done is not specified, so this operation may be used
- validly in compiling C code only for integer-valued operands.
-
-`(unsigned_fix:M X)'
- Represents the result of converting floating point value X to
- fixed point mode M, regarded as unsigned. How rounding is done is
- not specified.
-
-`(fix:M X)'
- When M is a floating point mode, represents the result of
- converting floating point value X (valid for mode M) to an
- integer, still represented in floating point mode M, by rounding
- towards zero.
-
-\1f
-File: gccint.info, Node: RTL Declarations, Next: Side Effects, Prev: Conversions, Up: RTL
-
-Declarations
-============
-
- Declaration expression codes do not represent arithmetic operations
-but rather state assertions about their operands.
-
-`(strict_low_part (subreg:M (reg:N R) 0))'
- This expression code is used in only one context: as the
- destination operand of a `set' expression. In addition, the
- operand of this expression must be a non-paradoxical `subreg'
- expression.
-
- The presence of `strict_low_part' says that the part of the
- register which is meaningful in mode N, but is not part of mode M,
- is not to be altered. Normally, an assignment to such a subreg is
- allowed to have undefined effects on the rest of the register when
- M is less than a word.
-
-\1f
-File: gccint.info, Node: Side Effects, Next: Incdec, Prev: RTL Declarations, Up: RTL
-
-Side Effect Expressions
-=======================
-
- The expression codes described so far represent values, not actions.
-But machine instructions never produce values; they are meaningful only
-for their side effects on the state of the machine. Special expression
-codes are used to represent side effects.
-
- The body of an instruction is always one of these side effect codes;
-the codes described above, which represent values, appear only as the
-operands of these.
-
-`(set LVAL X)'
- Represents the action of storing the value of X into the place
- represented by LVAL. LVAL must be an expression representing a
- place that can be stored in: `reg' (or `subreg' or
- `strict_low_part'), `mem', `pc', `parallel', or `cc0'.
-
- If LVAL is a `reg', `subreg' or `mem', it has a machine mode; then
- X must be valid for that mode.
-
- If LVAL is a `reg' whose machine mode is less than the full width
- of the register, then it means that the part of the register
- specified by the machine mode is given the specified value and the
- rest of the register receives an undefined value. Likewise, if
- LVAL is a `subreg' whose machine mode is narrower than the mode of
- the register, the rest of the register can be changed in an
- undefined way.
-
- If LVAL is a `strict_low_part' of a `subreg', then the part of the
- register specified by the machine mode of the `subreg' is given
- the value X and the rest of the register is not changed.
-
- If LVAL is `(cc0)', it has no machine mode, and X may be either a
- `compare' expression or a value that may have any mode. The
- latter case represents a "test" instruction. The expression `(set
- (cc0) (reg:M N))' is equivalent to `(set (cc0) (compare (reg:M N)
- (const_int 0)))'. Use the former expression to save space during
- the compilation.
-
- If LVAL is a `parallel', it is used to represent the case of a
- function returning a structure in multiple registers. Each element
- of the `parallel' is an `expr_list' whose first operand is a `reg'
- and whose second operand is a `const_int' representing the offset
- (in bytes) into the structure at which the data in that register
- corresponds. The first element may be null to indicate that the
- structure is also passed partly in memory.
-
- If LVAL is `(pc)', we have a jump instruction, and the
- possibilities for X are very limited. It may be a `label_ref'
- expression (unconditional jump). It may be an `if_then_else'
- (conditional jump), in which case either the second or the third
- operand must be `(pc)' (for the case which does not jump) and the
- other of the two must be a `label_ref' (for the case which does
- jump). X may also be a `mem' or `(plus:SI (pc) Y)', where Y may
- be a `reg' or a `mem'; these unusual patterns are used to
- represent jumps through branch tables.
-
- If LVAL is neither `(cc0)' nor `(pc)', the mode of LVAL must not
- be `VOIDmode' and the mode of X must be valid for the mode of LVAL.
-
- LVAL is customarily accessed with the `SET_DEST' macro and X with
- the `SET_SRC' macro.
-
-`(return)'
- As the sole expression in a pattern, represents a return from the
- current function, on machines where this can be done with one
- instruction, such as VAXen. On machines where a multi-instruction
- "epilogue" must be executed in order to return from the function,
- returning is done by jumping to a label which precedes the
- epilogue, and the `return' expression code is never used.
-
- Inside an `if_then_else' expression, represents the value to be
- placed in `pc' to return to the caller.
-
- Note that an insn pattern of `(return)' is logically equivalent to
- `(set (pc) (return))', but the latter form is never used.
-
-`(call FUNCTION NARGS)'
- Represents a function call. FUNCTION is a `mem' expression whose
- address is the address of the function to be called. NARGS is an
- expression which can be used for two purposes: on some machines it
- represents the number of bytes of stack argument; on others, it
- represents the number of argument registers.
-
- Each machine has a standard machine mode which FUNCTION must have.
- The machine description defines macro `FUNCTION_MODE' to expand
- into the requisite mode name. The purpose of this mode is to
- specify what kind of addressing is allowed, on machines where the
- allowed kinds of addressing depend on the machine mode being
- addressed.
-
-`(clobber X)'
- Represents the storing or possible storing of an unpredictable,
- undescribed value into X, which must be a `reg', `scratch',
- `parallel' or `mem' expression.
-
- One place this is used is in string instructions that store
- standard values into particular hard registers. It may not be
- worth the trouble to describe the values that are stored, but it
- is essential to inform the compiler that the registers will be
- altered, lest it attempt to keep data in them across the string
- instruction.
-
- If X is `(mem:BLK (const_int 0))', it means that all memory
- locations must be presumed clobbered. If X is a `parallel', it
- has the same meaning as a `parallel' in a `set' expression.
-
- Note that the machine description classifies certain hard
- registers as "call-clobbered". All function call instructions are
- assumed by default to clobber these registers, so there is no need
- to use `clobber' expressions to indicate this fact. Also, each
- function call is assumed to have the potential to alter any memory
- location, unless the function is declared `const'.
-
- If the last group of expressions in a `parallel' are each a
- `clobber' expression whose arguments are `reg' or `match_scratch'
- (*note RTL Template::) expressions, the combiner phase can add the
- appropriate `clobber' expressions to an insn it has constructed
- when doing so will cause a pattern to be matched.
-
- This feature can be used, for example, on a machine that whose
- multiply and add instructions don't use an MQ register but which
- has an add-accumulate instruction that does clobber the MQ
- register. Similarly, a combined instruction might require a
- temporary register while the constituent instructions might not.
-
- When a `clobber' expression for a register appears inside a
- `parallel' with other side effects, the register allocator
- guarantees that the register is unoccupied both before and after
- that insn. However, the reload phase may allocate a register used
- for one of the inputs unless the `&' constraint is specified for
- the selected alternative (*note Modifiers::). You can clobber
- either a specific hard register, a pseudo register, or a `scratch'
- expression; in the latter two cases, GCC will allocate a hard
- register that is available there for use as a temporary.
-
- For instructions that require a temporary register, you should use
- `scratch' instead of a pseudo-register because this will allow the
- combiner phase to add the `clobber' when required. You do this by
- coding (`clobber' (`match_scratch' ...)). If you do clobber a
- pseudo register, use one which appears nowhere else--generate a
- new one each time. Otherwise, you may confuse CSE.
-
- There is one other known use for clobbering a pseudo register in a
- `parallel': when one of the input operands of the insn is also
- clobbered by the insn. In this case, using the same pseudo
- register in the clobber and elsewhere in the insn produces the
- expected results.
-
-`(use X)'
- Represents the use of the value of X. It indicates that the value
- in X at this point in the program is needed, even though it may
- not be apparent why this is so. Therefore, the compiler will not
- attempt to delete previous instructions whose only effect is to
- store a value in X. X must be a `reg' expression.
-
- In some situations, it may be tempting to add a `use' of a
- register in a `parallel' to describe a situation where the value
- of a special register will modify the behavior of the instruction.
- An hypothetical example might be a pattern for an addition that can
- either wrap around or use saturating addition depending on the
- value of a special control register:
-
- (parallel [(set (reg:SI 2) (unspec:SI [(reg:SI 3)
- (reg:SI 4)] 0))
- (use (reg:SI 1))])
-
- This will not work, several of the optimizers only look at
- expressions locally; it is very likely that if you have multiple
- insns with identical inputs to the `unspec', they will be
- optimized away even if register 1 changes in between.
-
- This means that `use' can _only_ be used to describe that the
- register is live. You should think twice before adding `use'
- statements, more often you will want to use `unspec' instead. The
- `use' RTX is most commonly useful to describe that a fixed
- register is implicitly used in an insn. It is also safe to use in
- patterns where the compiler knows for other reasons that the result
- of the whole pattern is variable, such as `movstrM' or `call'
- patterns.
-
- During the reload phase, an insn that has a `use' as pattern can
- carry a reg_equal note. These `use' insns will be deleted before
- the reload phase exits.
-
- During the delayed branch scheduling phase, X may be an insn.
- This indicates that X previously was located at this place in the
- code and its data dependencies need to be taken into account.
- These `use' insns will be deleted before the delayed branch
- scheduling phase exits.
-
-`(parallel [X0 X1 ...])'
- Represents several side effects performed in parallel. The square
- brackets stand for a vector; the operand of `parallel' is a vector
- of expressions. X0, X1 and so on are individual side effect
- expressions--expressions of code `set', `call', `return',
- `clobber' or `use'.
-
- "In parallel" means that first all the values used in the
- individual side-effects are computed, and second all the actual
- side-effects are performed. For example,
-
- (parallel [(set (reg:SI 1) (mem:SI (reg:SI 1)))
- (set (mem:SI (reg:SI 1)) (reg:SI 1))])
-
- says unambiguously that the values of hard register 1 and the
- memory location addressed by it are interchanged. In both places
- where `(reg:SI 1)' appears as a memory address it refers to the
- value in register 1 _before_ the execution of the insn.
-
- It follows that it is _incorrect_ to use `parallel' and expect the
- result of one `set' to be available for the next one. For
- example, people sometimes attempt to represent a jump-if-zero
- instruction this way:
-
- (parallel [(set (cc0) (reg:SI 34))
- (set (pc) (if_then_else
- (eq (cc0) (const_int 0))
- (label_ref ...)
- (pc)))])
-
- But this is incorrect, because it says that the jump condition
- depends on the condition code value _before_ this instruction, not
- on the new value that is set by this instruction.
-
- Peephole optimization, which takes place together with final
- assembly code output, can produce insns whose patterns consist of
- a `parallel' whose elements are the operands needed to output the
- resulting assembler code--often `reg', `mem' or constant
- expressions. This would not be well-formed RTL at any other stage
- in compilation, but it is ok then because no further optimization
- remains to be done. However, the definition of the macro
- `NOTICE_UPDATE_CC', if any, must deal with such insns if you
- define any peephole optimizations.
-
-`(cond_exec [COND EXPR])'
- Represents a conditionally executed expression. The EXPR is
- executed only if the COND is nonzero. The COND expression must
- not have side-effects, but the EXPR may very well have
- side-effects.
-
-`(sequence [INSNS ...])'
- Represents a sequence of insns. Each of the INSNS that appears in
- the vector is suitable for appearing in the chain of insns, so it
- must be an `insn', `jump_insn', `call_insn', `code_label',
- `barrier' or `note'.
-
- A `sequence' RTX is never placed in an actual insn during RTL
- generation. It represents the sequence of insns that result from a
- `define_expand' _before_ those insns are passed to `emit_insn' to
- insert them in the chain of insns. When actually inserted, the
- individual sub-insns are separated out and the `sequence' is
- forgotten.
-
- After delay-slot scheduling is completed, an insn and all the
- insns that reside in its delay slots are grouped together into a
- `sequence'. The insn requiring the delay slot is the first insn
- in the vector; subsequent insns are to be placed in the delay slot.
-
- `INSN_ANNULLED_BRANCH_P' is set on an insn in a delay slot to
- indicate that a branch insn should be used that will conditionally
- annul the effect of the insns in the delay slots. In such a case,
- `INSN_FROM_TARGET_P' indicates that the insn is from the target of
- the branch and should be executed only if the branch is taken;
- otherwise the insn should be executed only if the branch is not
- taken. *Note Delay Slots::.
-
- These expression codes appear in place of a side effect, as the body
-of an insn, though strictly speaking they do not always describe side
-effects as such:
-
-`(asm_input S)'
- Represents literal assembler code as described by the string S.
-
-`(unspec [OPERANDS ...] INDEX)'
-`(unspec_volatile [OPERANDS ...] INDEX)'
- Represents a machine-specific operation on OPERANDS. INDEX
- selects between multiple machine-specific operations.
- `unspec_volatile' is used for volatile operations and operations
- that may trap; `unspec' is used for other operations.
-
- These codes may appear inside a `pattern' of an insn, inside a
- `parallel', or inside an expression.
-
-`(addr_vec:M [LR0 LR1 ...])'
- Represents a table of jump addresses. The vector elements LR0,
- etc., are `label_ref' expressions. The mode M specifies how much
- space is given to each address; normally M would be `Pmode'.
-
-`(addr_diff_vec:M BASE [LR0 LR1 ...] MIN MAX FLAGS)'
- Represents a table of jump addresses expressed as offsets from
- BASE. The vector elements LR0, etc., are `label_ref' expressions
- and so is BASE. The mode M specifies how much space is given to
- each address-difference. MIN and MAX are set up by branch
- shortening and hold a label with a minimum and a maximum address,
- respectively. FLAGS indicates the relative position of BASE, MIN
- and MAX to the containing insn and of MIN and MAX to BASE. See
- rtl.def for details.
-
-`(prefetch:M ADDR RW LOCALITY)'
- Represents prefetch of memory at address ADDR. Operand RW is 1 if
- the prefetch is for data to be written, 0 otherwise; targets that
- do not support write prefetches should treat this as a normal
- prefetch. Operand LOCALITY specifies the amount of temporal
- locality; 0 if there is none or 1, 2, or 3 for increasing levels
- of temporal locality; targets that do not support locality hints
- should ignore this.
-
- This insn is used to minimize cache-miss latency by moving data
- into a cache before it is accessed. It should use only
- non-faulting data prefetch instructions.
-
-\1f
-File: gccint.info, Node: Incdec, Next: Assembler, Prev: Side Effects, Up: RTL
-
-Embedded Side-Effects on Addresses
-==================================
-
- Six special side-effect expression codes appear as memory addresses.
-
-`(pre_dec:M X)'
- Represents the side effect of decrementing X by a standard amount
- and represents also the value that X has after being decremented.
- X must be a `reg' or `mem', but most machines allow only a `reg'.
- M must be the machine mode for pointers on the machine in use.
- The amount X is decremented by is the length in bytes of the
- machine mode of the containing memory reference of which this
- expression serves as the address. Here is an example of its use:
-
- (mem:DF (pre_dec:SI (reg:SI 39)))
-
- This says to decrement pseudo register 39 by the length of a
- `DFmode' value and use the result to address a `DFmode' value.
-
-`(pre_inc:M X)'
- Similar, but specifies incrementing X instead of decrementing it.
-
-`(post_dec:M X)'
- Represents the same side effect as `pre_dec' but a different
- value. The value represented here is the value X has before being
- decremented.
-
-`(post_inc:M X)'
- Similar, but specifies incrementing X instead of decrementing it.
-
-`(post_modify:M X Y)'
- Represents the side effect of setting X to Y and represents X
- before X is modified. X must be a `reg' or `mem', but most
- machines allow only a `reg'. M must be the machine mode for
- pointers on the machine in use. The amount X is decremented by is
- the length in bytes of the machine mode of the containing memory
- reference of which this expression serves as the address. Note
- that this is not currently implemented.
-
- The expression Y must be one of three forms:
- `(plus:M X Z)', `(minus:M X Z)', or `(plus:M X I)',
- where Z is an index register and I is a constant.
-
- Here is an example of its use:
-
- (mem:SF (post_modify:SI (reg:SI 42) (plus (reg:SI 42)
- (reg:SI 48))))
-
- This says to modify pseudo register 42 by adding the contents of
- pseudo register 48 to it, after the use of what ever 42 points to.
-
-`(pre_modify:M X EXPR)'
- Similar except side effects happen before the use.
-
- These embedded side effect expressions must be used with care.
-Instruction patterns may not use them. Until the `flow' pass of the
-compiler, they may occur only to represent pushes onto the stack. The
-`flow' pass finds cases where registers are incremented or decremented
-in one instruction and used as an address shortly before or after;
-these cases are then transformed to use pre- or post-increment or
--decrement.
-
- If a register used as the operand of these expressions is used in
-another address in an insn, the original value of the register is used.
-Uses of the register outside of an address are not permitted within the
-same insn as a use in an embedded side effect expression because such
-insns behave differently on different machines and hence must be treated
-as ambiguous and disallowed.
-
- An instruction that can be represented with an embedded side effect
-could also be represented using `parallel' containing an additional
-`set' to describe how the address register is altered. This is not
-done because machines that allow these operations at all typically
-allow them wherever a memory address is called for. Describing them as
-additional parallel stores would require doubling the number of entries
-in the machine description.
-
-\1f
-File: gccint.info, Node: Assembler, Next: Insns, Prev: Incdec, Up: RTL
-
-Assembler Instructions as Expressions
-=====================================
-
- The RTX code `asm_operands' represents a value produced by a
-user-specified assembler instruction. It is used to represent an `asm'
-statement with arguments. An `asm' statement with a single output
-operand, like this:
-
- asm ("foo %1,%2,%0" : "=a" (outputvar) : "g" (x + y), "di" (*z));
-
-is represented using a single `asm_operands' RTX which represents the
-value that is stored in `outputvar':
-
- (set RTX-FOR-OUTPUTVAR
- (asm_operands "foo %1,%2,%0" "a" 0
- [RTX-FOR-ADDITION-RESULT RTX-FOR-*Z]
- [(asm_input:M1 "g")
- (asm_input:M2 "di")]))
-
-Here the operands of the `asm_operands' RTX are the assembler template
-string, the output-operand's constraint, the index-number of the output
-operand among the output operands specified, a vector of input operand
-RTX's, and a vector of input-operand modes and constraints. The mode
-M1 is the mode of the sum `x+y'; M2 is that of `*z'.
-
- When an `asm' statement has multiple output values, its insn has
-several such `set' RTX's inside of a `parallel'. Each `set' contains a
-`asm_operands'; all of these share the same assembler template and
-vectors, but each contains the constraint for the respective output
-operand. They are also distinguished by the output-operand index
-number, which is 0, 1, ... for successive output operands.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Insns, Next: Calls, Prev: Assembler, Up: RTL
-
-Insns
-=====
-
- The RTL representation of the code for a function is a doubly-linked
-chain of objects called "insns". Insns are expressions with special
-codes that are used for no other purpose. Some insns are actual
-instructions; others represent dispatch tables for `switch' statements;
-others represent labels to jump to or various sorts of declarative
-information.
-
- In addition to its own specific data, each insn must have a unique
-id-number that distinguishes it from all other insns in the current
-function (after delayed branch scheduling, copies of an insn with the
-same id-number may be present in multiple places in a function, but
-these copies will always be identical and will only appear inside a
-`sequence'), and chain pointers to the preceding and following insns.
-These three fields occupy the same position in every insn, independent
-of the expression code of the insn. They could be accessed with `XEXP'
-and `XINT', but instead three special macros are always used:
-
-`INSN_UID (I)'
- Accesses the unique id of insn I.
-
-`PREV_INSN (I)'
- Accesses the chain pointer to the insn preceding I. If I is the
- first insn, this is a null pointer.
-
-`NEXT_INSN (I)'
- Accesses the chain pointer to the insn following I. If I is the
- last insn, this is a null pointer.
-
- The first insn in the chain is obtained by calling `get_insns'; the
-last insn is the result of calling `get_last_insn'. Within the chain
-delimited by these insns, the `NEXT_INSN' and `PREV_INSN' pointers must
-always correspond: if INSN is not the first insn,
-
- NEXT_INSN (PREV_INSN (INSN)) == INSN
-
-is always true and if INSN is not the last insn,
-
- PREV_INSN (NEXT_INSN (INSN)) == INSN
-
-is always true.
-
- After delay slot scheduling, some of the insns in the chain might be
-`sequence' expressions, which contain a vector of insns. The value of
-`NEXT_INSN' in all but the last of these insns is the next insn in the
-vector; the value of `NEXT_INSN' of the last insn in the vector is the
-same as the value of `NEXT_INSN' for the `sequence' in which it is
-contained. Similar rules apply for `PREV_INSN'.
-
- This means that the above invariants are not necessarily true for
-insns inside `sequence' expressions. Specifically, if INSN is the
-first insn in a `sequence', `NEXT_INSN (PREV_INSN (INSN))' is the insn
-containing the `sequence' expression, as is the value of `PREV_INSN
-(NEXT_INSN (INSN))' if INSN is the last insn in the `sequence'
-expression. You can use these expressions to find the containing
-`sequence' expression.
-
- Every insn has one of the following six expression codes:
-
-`insn'
- The expression code `insn' is used for instructions that do not
- jump and do not do function calls. `sequence' expressions are
- always contained in insns with code `insn' even if one of those
- insns should jump or do function calls.
-
- Insns with code `insn' have four additional fields beyond the three
- mandatory ones listed above. These four are described in a table
- below.
-
-`jump_insn'
- The expression code `jump_insn' is used for instructions that may
- jump (or, more generally, may contain `label_ref' expressions). If
- there is an instruction to return from the current function, it is
- recorded as a `jump_insn'.
-
- `jump_insn' insns have the same extra fields as `insn' insns,
- accessed in the same way and in addition contain a field
- `JUMP_LABEL' which is defined once jump optimization has completed.
-
- For simple conditional and unconditional jumps, this field contains
- the `code_label' to which this insn will (possibly conditionally)
- branch. In a more complex jump, `JUMP_LABEL' records one of the
- labels that the insn refers to; the only way to find the others is
- to scan the entire body of the insn. In an `addr_vec',
- `JUMP_LABEL' is `NULL_RTX'.
-
- Return insns count as jumps, but since they do not refer to any
- labels, their `JUMP_LABEL' is `NULL_RTX'.
-
-`call_insn'
- The expression code `call_insn' is used for instructions that may
- do function calls. It is important to distinguish these
- instructions because they imply that certain registers and memory
- locations may be altered unpredictably.
-
- `call_insn' insns have the same extra fields as `insn' insns,
- accessed in the same way and in addition contain a field
- `CALL_INSN_FUNCTION_USAGE', which contains a list (chain of
- `expr_list' expressions) containing `use' and `clobber'
- expressions that denote hard registers and `MEM's used or
- clobbered by the called function.
-
- A `MEM' generally points to a stack slots in which arguments passed
- to the libcall by reference (*note FUNCTION_ARG_PASS_BY_REFERENCE:
- Register Arguments.) are stored. If the argument is caller-copied
- (*note FUNCTION_ARG_CALLEE_COPIES: Register Arguments.), the stack
- slot will be mentioned in `CLOBBER' and `USE' entries; if it's
- callee-copied, only a `USE' will appear, and the `MEM' may point
- to addresses that are not stack slots. These `MEM's are used only
- in libcalls, because, unlike regular function calls, `CONST_CALL's
- (which libcalls generally are, *note CONST_CALL_P: Flags.) aren't
- assumed to read and write all memory, so flow would consider the
- stores dead and remove them. Note that, since a libcall must
- never return values in memory (*note RETURN_IN_MEMORY: Aggregate
- Return.), there will never be a `CLOBBER' for a memory address
- holding a return value.
-
- `CLOBBER'ed registers in this list augment registers specified in
- `CALL_USED_REGISTERS' (*note Register Basics::).
-
-`code_label'
- A `code_label' insn represents a label that a jump insn can jump
- to. It contains two special fields of data in addition to the
- three standard ones. `CODE_LABEL_NUMBER' is used to hold the
- "label number", a number that identifies this label uniquely among
- all the labels in the compilation (not just in the current
- function). Ultimately, the label is represented in the assembler
- output as an assembler label, usually of the form `LN' where N is
- the label number.
-
- When a `code_label' appears in an RTL expression, it normally
- appears within a `label_ref' which represents the address of the
- label, as a number.
-
- Besides as a `code_label', a label can also be represented as a
- `note' of type `NOTE_INSN_DELETED_LABEL'.
-
- The field `LABEL_NUSES' is only defined once the jump optimization
- phase is completed and contains the number of times this label is
- referenced in the current function.
-
- The field `LABEL_ALTERNATE_NAME' is used to associate a name with
- a `code_label'. If this field is defined, the alternate name will
- be emitted instead of an internally generated label name.
-
-`barrier'
- Barriers are placed in the instruction stream when control cannot
- flow past them. They are placed after unconditional jump
- instructions to indicate that the jumps are unconditional and
- after calls to `volatile' functions, which do not return (e.g.,
- `exit'). They contain no information beyond the three standard
- fields.
-
-`note'
- `note' insns are used to represent additional debugging and
- declarative information. They contain two nonstandard fields, an
- integer which is accessed with the macro `NOTE_LINE_NUMBER' and a
- string accessed with `NOTE_SOURCE_FILE'.
-
- If `NOTE_LINE_NUMBER' is positive, the note represents the
- position of a source line and `NOTE_SOURCE_FILE' is the source
- file name that the line came from. These notes control generation
- of line number data in the assembler output.
-
- Otherwise, `NOTE_LINE_NUMBER' is not really a line number but a
- code with one of the following values (and `NOTE_SOURCE_FILE' must
- contain a null pointer):
-
- `NOTE_INSN_DELETED'
- Such a note is completely ignorable. Some passes of the
- compiler delete insns by altering them into notes of this
- kind.
-
- `NOTE_INSN_DELETED_LABEL'
- This marks what used to be a `code_label', but was not used
- for other purposes than taking its address and was
- transformed to mark that no code jumps to it.
-
- `NOTE_INSN_BLOCK_BEG'
- `NOTE_INSN_BLOCK_END'
- These types of notes indicate the position of the beginning
- and end of a level of scoping of variable names. They
- control the output of debugging information.
-
- `NOTE_INSN_EH_REGION_BEG'
- `NOTE_INSN_EH_REGION_END'
- These types of notes indicate the position of the beginning
- and end of a level of scoping for exception handling.
- `NOTE_BLOCK_NUMBER' identifies which `CODE_LABEL' or `note'
- of type `NOTE_INSN_DELETED_LABEL' is associated with the
- given region.
-
- `NOTE_INSN_LOOP_BEG'
- `NOTE_INSN_LOOP_END'
- These types of notes indicate the position of the beginning
- and end of a `while' or `for' loop. They enable the loop
- optimizer to find loops quickly.
-
- `NOTE_INSN_LOOP_CONT'
- Appears at the place in a loop that `continue' statements
- jump to.
-
- `NOTE_INSN_LOOP_VTOP'
- This note indicates the place in a loop where the exit test
- begins for those loops in which the exit test has been
- duplicated. This position becomes another virtual start of
- the loop when considering loop invariants.
-
- `NOTE_INSN_FUNCTION_END'
- Appears near the end of the function body, just before the
- label that `return' statements jump to (on machine where a
- single instruction does not suffice for returning). This
- note may be deleted by jump optimization.
-
- `NOTE_INSN_SETJMP'
- Appears following each call to `setjmp' or a related function.
-
- These codes are printed symbolically when they appear in debugging
- dumps.
-
- The machine mode of an insn is normally `VOIDmode', but some phases
-use the mode for various purposes.
-
- The common subexpression elimination pass sets the mode of an insn to
-`QImode' when it is the first insn in a block that has already been
-processed.
-
- The second Haifa scheduling pass, for targets that can multiple
-issue, sets the mode of an insn to `TImode' when it is believed that the
-instruction begins an issue group. That is, when the instruction
-cannot issue simultaneously with the previous. This may be relied on
-by later passes, in particular machine-dependent reorg.
-
- Here is a table of the extra fields of `insn', `jump_insn' and
-`call_insn' insns:
-
-`PATTERN (I)'
- An expression for the side effect performed by this insn. This
- must be one of the following codes: `set', `call', `use',
- `clobber', `return', `asm_input', `asm_output', `addr_vec',
- `addr_diff_vec', `trap_if', `unspec', `unspec_volatile',
- `parallel', `cond_exec', or `sequence'. If it is a `parallel',
- each element of the `parallel' must be one these codes, except that
- `parallel' expressions cannot be nested and `addr_vec' and
- `addr_diff_vec' are not permitted inside a `parallel' expression.
-
-`INSN_CODE (I)'
- An integer that says which pattern in the machine description
- matches this insn, or -1 if the matching has not yet been
- attempted.
-
- Such matching is never attempted and this field remains -1 on an
- insn whose pattern consists of a single `use', `clobber',
- `asm_input', `addr_vec' or `addr_diff_vec' expression.
-
- Matching is also never attempted on insns that result from an `asm'
- statement. These contain at least one `asm_operands' expression.
- The function `asm_noperands' returns a non-negative value for such
- insns.
-
- In the debugging output, this field is printed as a number
- followed by a symbolic representation that locates the pattern in
- the `md' file as some small positive or negative offset from a
- named pattern.
-
-`LOG_LINKS (I)'
- A list (chain of `insn_list' expressions) giving information about
- dependencies between instructions within a basic block. Neither a
- jump nor a label may come between the related insns.
-
-`REG_NOTES (I)'
- A list (chain of `expr_list' and `insn_list' expressions) giving
- miscellaneous information about the insn. It is often information
- pertaining to the registers used in this insn.
-
- The `LOG_LINKS' field of an insn is a chain of `insn_list'
-expressions. Each of these has two operands: the first is an insn, and
-the second is another `insn_list' expression (the next one in the
-chain). The last `insn_list' in the chain has a null pointer as second
-operand. The significant thing about the chain is which insns appear
-in it (as first operands of `insn_list' expressions). Their order is
-not significant.
-
- This list is originally set up by the flow analysis pass; it is a
-null pointer until then. Flow only adds links for those data
-dependencies which can be used for instruction combination. For each
-insn, the flow analysis pass adds a link to insns which store into
-registers values that are used for the first time in this insn. The
-instruction scheduling pass adds extra links so that every dependence
-will be represented. Links represent data dependencies,
-antidependencies and output dependencies; the machine mode of the link
-distinguishes these three types: antidependencies have mode
-`REG_DEP_ANTI', output dependencies have mode `REG_DEP_OUTPUT', and
-data dependencies have mode `VOIDmode'.
-
- The `REG_NOTES' field of an insn is a chain similar to the
-`LOG_LINKS' field but it includes `expr_list' expressions in addition
-to `insn_list' expressions. There are several kinds of register notes,
-which are distinguished by the machine mode, which in a register note
-is really understood as being an `enum reg_note'. The first operand OP
-of the note is data whose meaning depends on the kind of note.
-
- The macro `REG_NOTE_KIND (X)' returns the kind of register note.
-Its counterpart, the macro `PUT_REG_NOTE_KIND (X, NEWKIND)' sets the
-register note type of X to be NEWKIND.
-
- Register notes are of three classes: They may say something about an
-input to an insn, they may say something about an output of an insn, or
-they may create a linkage between two insns. There are also a set of
-values that are only used in `LOG_LINKS'.
-
- These register notes annotate inputs to an insn:
-
-`REG_DEAD'
- The value in OP dies in this insn; that is to say, altering the
- value immediately after this insn would not affect the future
- behavior of the program.
-
- It does not follow that the register OP has no useful value after
- this insn since OP is not necessarily modified by this insn.
- Rather, no subsequent instruction uses the contents of OP.
-
-`REG_UNUSED'
- The register OP being set by this insn will not be used in a
- subsequent insn. This differs from a `REG_DEAD' note, which
- indicates that the value in an input will not be used subsequently.
- These two notes are independent; both may be present for the same
- register.
-
-`REG_INC'
- The register OP is incremented (or decremented; at this level
- there is no distinction) by an embedded side effect inside this
- insn. This means it appears in a `post_inc', `pre_inc',
- `post_dec' or `pre_dec' expression.
-
-`REG_NONNEG'
- The register OP is known to have a nonnegative value when this
- insn is reached. This is used so that decrement and branch until
- zero instructions, such as the m68k dbra, can be matched.
-
- The `REG_NONNEG' note is added to insns only if the machine
- description has a `decrement_and_branch_until_zero' pattern.
-
-`REG_NO_CONFLICT'
- This insn does not cause a conflict between OP and the item being
- set by this insn even though it might appear that it does. In
- other words, if the destination register and OP could otherwise be
- assigned the same register, this insn does not prevent that
- assignment.
-
- Insns with this note are usually part of a block that begins with a
- `clobber' insn specifying a multi-word pseudo register (which will
- be the output of the block), a group of insns that each set one
- word of the value and have the `REG_NO_CONFLICT' note attached,
- and a final insn that copies the output to itself with an attached
- `REG_EQUAL' note giving the expression being computed. This block
- is encapsulated with `REG_LIBCALL' and `REG_RETVAL' notes on the
- first and last insns, respectively.
-
-`REG_LABEL'
- This insn uses OP, a `code_label' or a `note' of type
- `NOTE_INSN_DELETED_LABEL', but is not a `jump_insn', or it is a
- `jump_insn' that required the label to be held in a register. The
- presence of this note allows jump optimization to be aware that OP
- is, in fact, being used, and flow optimization to build an
- accurate flow graph.
-
- The following notes describe attributes of outputs of an insn:
-
-`REG_EQUIV'
-`REG_EQUAL'
- This note is only valid on an insn that sets only one register and
- indicates that that register will be equal to OP at run time; the
- scope of this equivalence differs between the two types of notes.
- The value which the insn explicitly copies into the register may
- look different from OP, but they will be equal at run time. If the
- output of the single `set' is a `strict_low_part' expression, the
- note refers to the register that is contained in `SUBREG_REG' of
- the `subreg' expression.
-
- For `REG_EQUIV', the register is equivalent to OP throughout the
- entire function, and could validly be replaced in all its
- occurrences by OP. ("Validly" here refers to the data flow of the
- program; simple replacement may make some insns invalid.) For
- example, when a constant is loaded into a register that is never
- assigned any other value, this kind of note is used.
-
- When a parameter is copied into a pseudo-register at entry to a
- function, a note of this kind records that the register is
- equivalent to the stack slot where the parameter was passed.
- Although in this case the register may be set by other insns, it
- is still valid to replace the register by the stack slot
- throughout the function.
-
- A `REG_EQUIV' note is also used on an instruction which copies a
- register parameter into a pseudo-register at entry to a function,
- if there is a stack slot where that parameter could be stored.
- Although other insns may set the pseudo-register, it is valid for
- the compiler to replace the pseudo-register by stack slot
- throughout the function, provided the compiler ensures that the
- stack slot is properly initialized by making the replacement in
- the initial copy instruction as well. This is used on machines
- for which the calling convention allocates stack space for
- register parameters. See `REG_PARM_STACK_SPACE' in *Note Stack
- Arguments::.
-
- In the case of `REG_EQUAL', the register that is set by this insn
- will be equal to OP at run time at the end of this insn but not
- necessarily elsewhere in the function. In this case, OP is
- typically an arithmetic expression. For example, when a sequence
- of insns such as a library call is used to perform an arithmetic
- operation, this kind of note is attached to the insn that produces
- or copies the final value.
-
- These two notes are used in different ways by the compiler passes.
- `REG_EQUAL' is used by passes prior to register allocation (such as
- common subexpression elimination and loop optimization) to tell
- them how to think of that value. `REG_EQUIV' notes are used by
- register allocation to indicate that there is an available
- substitute expression (either a constant or a `mem' expression for
- the location of a parameter on the stack) that may be used in
- place of a register if insufficient registers are available.
-
- Except for stack homes for parameters, which are indicated by a
- `REG_EQUIV' note and are not useful to the early optimization
- passes and pseudo registers that are equivalent to a memory
- location throughout their entire life, which is not detected until
- later in the compilation, all equivalences are initially indicated
- by an attached `REG_EQUAL' note. In the early stages of register
- allocation, a `REG_EQUAL' note is changed into a `REG_EQUIV' note
- if OP is a constant and the insn represents the only set of its
- destination register.
-
- Thus, compiler passes prior to register allocation need only check
- for `REG_EQUAL' notes and passes subsequent to register allocation
- need only check for `REG_EQUIV' notes.
-
-`REG_WAS_0'
- The single output of this insn contained zero before this insn.
- OP is the insn that set it to zero. You can rely on this note if
- it is present and OP has not been deleted or turned into a `note';
- its absence implies nothing.
-
- These notes describe linkages between insns. They occur in pairs:
-one insn has one of a pair of notes that points to a second insn, which
-has the inverse note pointing back to the first insn.
-
-`REG_RETVAL'
- This insn copies the value of a multi-insn sequence (for example, a
- library call), and OP is the first insn of the sequence (for a
- library call, the first insn that was generated to set up the
- arguments for the library call).
-
- Loop optimization uses this note to treat such a sequence as a
- single operation for code motion purposes and flow analysis uses
- this note to delete such sequences whose results are dead.
-
- A `REG_EQUAL' note will also usually be attached to this insn to
- provide the expression being computed by the sequence.
-
- These notes will be deleted after reload, since they are no longer
- accurate or useful.
-
-`REG_LIBCALL'
- This is the inverse of `REG_RETVAL': it is placed on the first
- insn of a multi-insn sequence, and it points to the last one.
-
- These notes are deleted after reload, since they are no longer
- useful or accurate.
-
-`REG_CC_SETTER'
-`REG_CC_USER'
- On machines that use `cc0', the insns which set and use `cc0' set
- and use `cc0' are adjacent. However, when branch delay slot
- filling is done, this may no longer be true. In this case a
- `REG_CC_USER' note will be placed on the insn setting `cc0' to
- point to the insn using `cc0' and a `REG_CC_SETTER' note will be
- placed on the insn using `cc0' to point to the insn setting `cc0'.
-
- These values are only used in the `LOG_LINKS' field, and indicate
-the type of dependency that each link represents. Links which indicate
-a data dependence (a read after write dependence) do not use any code,
-they simply have mode `VOIDmode', and are printed without any
-descriptive text.
-
-`REG_DEP_ANTI'
- This indicates an anti dependence (a write after read dependence).
-
-`REG_DEP_OUTPUT'
- This indicates an output dependence (a write after write
- dependence).
-
- These notes describe information gathered from gcov profile data.
-They are stored in the `REG_NOTES' field of an insn as an `expr_list'.
-
-`REG_EXEC_COUNT'
- This is used to indicate the number of times a basic block was
- executed according to the profile data. The note is attached to
- the first insn in the basic block.
-
-`REG_BR_PROB'
- This is used to specify the ratio of branches to non-branches of a
- branch insn according to the profile data. The value is stored as
- a value between 0 and REG_BR_PROB_BASE; larger values indicate a
- higher probability that the branch will be taken.
-
-`REG_BR_PRED'
- These notes are found in JUMP insns after delayed branch scheduling
- has taken place. They indicate both the direction and the
- likelihood of the JUMP. The format is a bitmask of ATTR_FLAG_*
- values.
-
-`REG_FRAME_RELATED_EXPR'
- This is used on an RTX_FRAME_RELATED_P insn wherein the attached
- expression is used in place of the actual insn pattern. This is
- done in cases where the pattern is either complex or misleading.
-
- For convenience, the machine mode in an `insn_list' or `expr_list'
-is printed using these symbolic codes in debugging dumps.
-
- The only difference between the expression codes `insn_list' and
-`expr_list' is that the first operand of an `insn_list' is assumed to
-be an insn and is printed in debugging dumps as the insn's unique id;
-the first operand of an `expr_list' is printed in the ordinary way as
-an expression.
-
-\1f
-File: gccint.info, Node: Calls, Next: Sharing, Prev: Insns, Up: RTL
-
-RTL Representation of Function-Call Insns
-=========================================
-
- Insns that call subroutines have the RTL expression code `call_insn'.
-These insns must satisfy special rules, and their bodies must use a
-special RTL expression code, `call'.
-
- A `call' expression has two operands, as follows:
-
- (call (mem:FM ADDR) NBYTES)
-
-Here NBYTES is an operand that represents the number of bytes of
-argument data being passed to the subroutine, FM is a machine mode
-(which must equal as the definition of the `FUNCTION_MODE' macro in the
-machine description) and ADDR represents the address of the subroutine.
-
- For a subroutine that returns no value, the `call' expression as
-shown above is the entire body of the insn, except that the insn might
-also contain `use' or `clobber' expressions.
-
- For a subroutine that returns a value whose mode is not `BLKmode',
-the value is returned in a hard register. If this register's number is
-R, then the body of the call insn looks like this:
-
- (set (reg:M R)
- (call (mem:FM ADDR) NBYTES))
-
-This RTL expression makes it clear (to the optimizer passes) that the
-appropriate register receives a useful value in this insn.
-
- When a subroutine returns a `BLKmode' value, it is handled by
-passing to the subroutine the address of a place to store the value.
-So the call insn itself does not "return" any value, and it has the
-same RTL form as a call that returns nothing.
-
- On some machines, the call instruction itself clobbers some register,
-for example to contain the return address. `call_insn' insns on these
-machines should have a body which is a `parallel' that contains both
-the `call' expression and `clobber' expressions that indicate which
-registers are destroyed. Similarly, if the call instruction requires
-some register other than the stack pointer that is not explicitly
-mentioned it its RTL, a `use' subexpression should mention that
-register.
-
- Functions that are called are assumed to modify all registers listed
-in the configuration macro `CALL_USED_REGISTERS' (*note Register
-Basics::) and, with the exception of `const' functions and library
-calls, to modify all of memory.
-
- Insns containing just `use' expressions directly precede the
-`call_insn' insn to indicate which registers contain inputs to the
-function. Similarly, if registers other than those in
-`CALL_USED_REGISTERS' are clobbered by the called function, insns
-containing a single `clobber' follow immediately after the call to
-indicate which registers.
-
-\1f
-File: gccint.info, Node: Sharing, Next: Reading RTL, Prev: Calls, Up: RTL
-
-Structure Sharing Assumptions
-=============================
-
- The compiler assumes that certain kinds of RTL expressions are
-unique; there do not exist two distinct objects representing the same
-value. In other cases, it makes an opposite assumption: that no RTL
-expression object of a certain kind appears in more than one place in
-the containing structure.
-
- These assumptions refer to a single function; except for the RTL
-objects that describe global variables and external functions, and a
-few standard objects such as small integer constants, no RTL objects
-are common to two functions.
-
- * Each pseudo-register has only a single `reg' object to represent
- it, and therefore only a single machine mode.
-
- * For any symbolic label, there is only one `symbol_ref' object
- referring to it.
-
- * All `const_int' expressions with equal values are shared.
-
- * There is only one `pc' expression.
-
- * There is only one `cc0' expression.
-
- * There is only one `const_double' expression with value 0 for each
- floating point mode. Likewise for values 1 and 2.
-
- * There is only one `const_vector' expression with value 0 for each
- vector mode, be it an integer or a double constant vector.
-
- * No `label_ref' or `scratch' appears in more than one place in the
- RTL structure; in other words, it is safe to do a tree-walk of all
- the insns in the function and assume that each time a `label_ref'
- or `scratch' is seen it is distinct from all others that are seen.
-
- * Only one `mem' object is normally created for each static variable
- or stack slot, so these objects are frequently shared in all the
- places they appear. However, separate but equal objects for these
- variables are occasionally made.
-
- * When a single `asm' statement has multiple output operands, a
- distinct `asm_operands' expression is made for each output operand.
- However, these all share the vector which contains the sequence of
- input operands. This sharing is used later on to test whether two
- `asm_operands' expressions come from the same statement, so all
- optimizations must carefully preserve the sharing if they copy the
- vector at all.
-
- * No RTL object appears in more than one place in the RTL structure
- except as described above. Many passes of the compiler rely on
- this by assuming that they can modify RTL objects in place without
- unwanted side-effects on other insns.
-
- * During initial RTL generation, shared structure is freely
- introduced. After all the RTL for a function has been generated,
- all shared structure is copied by `unshare_all_rtl' in
- `emit-rtl.c', after which the above rules are guaranteed to be
- followed.
-
- * During the combiner pass, shared structure within an insn can exist
- temporarily. However, the shared structure is copied before the
- combiner is finished with the insn. This is done by calling
- `copy_rtx_if_shared', which is a subroutine of `unshare_all_rtl'.
-
-\1f
-File: gccint.info, Node: Reading RTL, Prev: Sharing, Up: RTL
-
-Reading RTL
-===========
-
- To read an RTL object from a file, call `read_rtx'. It takes one
-argument, a stdio stream, and returns a single RTL object. This routine
-is defined in `read-rtl.c'. It is not available in the compiler
-itself, only the various programs that generate the compiler back end
-from the machine description.
-
- People frequently have the idea of using RTL stored as text in a
-file as an interface between a language front end and the bulk of GCC.
-This idea is not feasible.
-
- GCC was designed to use RTL internally only. Correct RTL for a given
-program is very dependent on the particular target machine. And the RTL
-does not contain all the information about the program.
-
- The proper way to interface GCC to a new language front end is with
-the "tree" data structure, described in the files `tree.h' and
-`tree.def'. The documentation for this structure (*note Trees::) is
-incomplete.
-
-\1f
-File: gccint.info, Node: Machine Desc, Next: Target Macros, Prev: RTL, Up: Top
-
-Machine Descriptions
-********************
-
- A machine description has two parts: a file of instruction patterns
-(`.md' file) and a C header file of macro definitions.
-
- The `.md' file for a target machine contains a pattern for each
-instruction that the target machine supports (or at least each
-instruction that is worth telling the compiler about). It may also
-contain comments. A semicolon causes the rest of the line to be a
-comment, unless the semicolon is inside a quoted string.
-
- See the next chapter for information on the C header file.
-
-* Menu:
-
-* Overview:: How the machine description is used.
-* Patterns:: How to write instruction patterns.
-* Example:: An explained example of a `define_insn' pattern.
-* RTL Template:: The RTL template defines what insns match a pattern.
-* Output Template:: The output template says how to make assembler code
- from such an insn.
-* Output Statement:: For more generality, write C code to output
- the assembler code.
-* Constraints:: When not all operands are general operands.
-* Standard Names:: Names mark patterns to use for code generation.
-* Pattern Ordering:: When the order of patterns makes a difference.
-* Dependent Patterns:: Having one pattern may make you need another.
-* Jump Patterns:: Special considerations for patterns for jump insns.
-* Looping Patterns:: How to define patterns for special looping insns.
-* Insn Canonicalizations::Canonicalization of Instructions
-* Expander Definitions::Generating a sequence of several RTL insns
- for a standard operation.
-* Insn Splitting:: Splitting Instructions into Multiple Instructions.
-* Including Patterns:: Including Patterns in Machine Descriptions.
-* Peephole Definitions::Defining machine-specific peephole optimizations.
-* Insn Attributes:: Specifying the value of attributes for generated insns.
-* Conditional Execution::Generating `define_insn' patterns for
- predication.
-* Constant Definitions::Defining symbolic constants that can be used in the
- md file.
-
-\1f
-File: gccint.info, Node: Overview, Next: Patterns, Up: Machine Desc
-
-Overview of How the Machine Description is Used
-===============================================
-
- There are three main conversions that happen in the compiler:
-
- 1. The front end reads the source code and builds a parse tree.
-
- 2. The parse tree is used to generate an RTL insn list based on named
- instruction patterns.
-
- 3. The insn list is matched against the RTL templates to produce
- assembler code.
-
-
- For the generate pass, only the names of the insns matter, from
-either a named `define_insn' or a `define_expand'. The compiler will
-choose the pattern with the right name and apply the operands according
-to the documentation later in this chapter, without regard for the RTL
-template or operand constraints. Note that the names the compiler looks
-for are hard-coded in the compiler--it will ignore unnamed patterns and
-patterns with names it doesn't know about, but if you don't provide a
-named pattern it needs, it will abort.
-
- If a `define_insn' is used, the template given is inserted into the
-insn list. If a `define_expand' is used, one of three things happens,
-based on the condition logic. The condition logic may manually create
-new insns for the insn list, say via `emit_insn()', and invoke `DONE'.
-For certain named patterns, it may invoke `FAIL' to tell the compiler
-to use an alternate way of performing that task. If it invokes neither
-`DONE' nor `FAIL', the template given in the pattern is inserted, as if
-the `define_expand' were a `define_insn'.
-
- Once the insn list is generated, various optimization passes convert,
-replace, and rearrange the insns in the insn list. This is where the
-`define_split' and `define_peephole' patterns get used, for example.
-
- Finally, the insn list's RTL is matched up with the RTL templates in
-the `define_insn' patterns, and those patterns are used to emit the
-final assembly code. For this purpose, each named `define_insn' acts
-like it's unnamed, since the names are ignored.
-
-\1f
-File: gccint.info, Node: Patterns, Next: Example, Prev: Overview, Up: Machine Desc
-
-Everything about Instruction Patterns
-=====================================
-
- Each instruction pattern contains an incomplete RTL expression, with
-pieces to be filled in later, operand constraints that restrict how the
-pieces can be filled in, and an output pattern or C code to generate
-the assembler output, all wrapped up in a `define_insn' expression.
-
- A `define_insn' is an RTL expression containing four or five
-operands:
-
- 1. An optional name. The presence of a name indicate that this
- instruction pattern can perform a certain standard job for the
- RTL-generation pass of the compiler. This pass knows certain
- names and will use the instruction patterns with those names, if
- the names are defined in the machine description.
-
- The absence of a name is indicated by writing an empty string
- where the name should go. Nameless instruction patterns are never
- used for generating RTL code, but they may permit several simpler
- insns to be combined later on.
-
- Names that are not thus known and used in RTL-generation have no
- effect; they are equivalent to no name at all.
-
- For the purpose of debugging the compiler, you may also specify a
- name beginning with the `*' character. Such a name is used only
- for identifying the instruction in RTL dumps; it is entirely
- equivalent to having a nameless pattern for all other purposes.
-
- 2. The "RTL template" (*note RTL Template::) is a vector of incomplete
- RTL expressions which show what the instruction should look like.
- It is incomplete because it may contain `match_operand',
- `match_operator', and `match_dup' expressions that stand for
- operands of the instruction.
-
- If the vector has only one element, that element is the template
- for the instruction pattern. If the vector has multiple elements,
- then the instruction pattern is a `parallel' expression containing
- the elements described.
-
- 3. A condition. This is a string which contains a C expression that
- is the final test to decide whether an insn body matches this
- pattern.
-
- For a named pattern, the condition (if present) may not depend on
- the data in the insn being matched, but only the
- target-machine-type flags. The compiler needs to test these
- conditions during initialization in order to learn exactly which
- named instructions are available in a particular run.
-
- For nameless patterns, the condition is applied only when matching
- an individual insn, and only after the insn has matched the
- pattern's recognition template. The insn's operands may be found
- in the vector `operands'. For an insn where the condition has
- once matched, it can't be used to control register allocation, for
- example by excluding certain hard registers or hard register
- combinations.
-
- 4. The "output template": a string that says how to output matching
- insns as assembler code. `%' in this string specifies where to
- substitute the value of an operand. *Note Output Template::.
-
- When simple substitution isn't general enough, you can specify a
- piece of C code to compute the output. *Note Output Statement::.
-
- 5. Optionally, a vector containing the values of attributes for insns
- matching this pattern. *Note Insn Attributes::.
-
-\1f
-File: gccint.info, Node: Example, Next: RTL Template, Prev: Patterns, Up: Machine Desc
-
-Example of `define_insn'
-========================
-
- Here is an actual example of an instruction pattern, for the
-68000/68020.
-
- (define_insn "tstsi"
- [(set (cc0)
- (match_operand:SI 0 "general_operand" "rm"))]
- ""
- "*
- {
- if (TARGET_68020 || ! ADDRESS_REG_P (operands[0]))
- return \"tstl %0\";
- return \"cmpl #0,%0\";
- }")
-
-This can also be written using braced strings:
-
- (define_insn "tstsi"
- [(set (cc0)
- (match_operand:SI 0 "general_operand" "rm"))]
- ""
- {
- if (TARGET_68020 || ! ADDRESS_REG_P (operands[0]))
- return "tstl %0";
- return "cmpl #0,%0";
- })
-
- This is an instruction that sets the condition codes based on the
-value of a general operand. It has no condition, so any insn whose RTL
-description has the form shown may be handled according to this
-pattern. The name `tstsi' means "test a `SImode' value" and tells the
-RTL generation pass that, when it is necessary to test such a value, an
-insn to do so can be constructed using this pattern.
-
- The output control string is a piece of C code which chooses which
-output template to return based on the kind of operand and the specific
-type of CPU for which code is being generated.
-
- `"rm"' is an operand constraint. Its meaning is explained below.
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: RTL Template, Next: Output Template, Prev: Example, Up: Machine Desc
-
-RTL Template
-============
-
- The RTL template is used to define which insns match the particular
-pattern and how to find their operands. For named patterns, the RTL
-template also says how to construct an insn from specified operands.
-
- Construction involves substituting specified operands into a copy of
-the template. Matching involves determining the values that serve as
-the operands in the insn being matched. Both of these activities are
-controlled by special expression types that direct matching and
-substitution of the operands.
-
-`(match_operand:M N PREDICATE CONSTRAINT)'
- This expression is a placeholder for operand number N of the insn.
- When constructing an insn, operand number N will be substituted
- at this point. When matching an insn, whatever appears at this
- position in the insn will be taken as operand number N; but it
- must satisfy PREDICATE or this instruction pattern will not match
- at all.
-
- Operand numbers must be chosen consecutively counting from zero in
- each instruction pattern. There may be only one `match_operand'
- expression in the pattern for each operand number. Usually
- operands are numbered in the order of appearance in `match_operand'
- expressions. In the case of a `define_expand', any operand numbers
- used only in `match_dup' expressions have higher values than all
- other operand numbers.
-
- PREDICATE is a string that is the name of a C function that
- accepts two arguments, an expression and a machine mode. During
- matching, the function will be called with the putative operand as
- the expression and M as the mode argument (if M is not specified,
- `VOIDmode' will be used, which normally causes PREDICATE to accept
- any mode). If it returns zero, this instruction pattern fails to
- match. PREDICATE may be an empty string; then it means no test is
- to be done on the operand, so anything which occurs in this
- position is valid.
-
- Most of the time, PREDICATE will reject modes other than M--but
- not always. For example, the predicate `address_operand' uses M
- as the mode of memory ref that the address should be valid for.
- Many predicates accept `const_int' nodes even though their mode is
- `VOIDmode'.
-
- CONSTRAINT controls reloading and the choice of the best register
- class to use for a value, as explained later (*note Constraints::).
-
- People are often unclear on the difference between the constraint
- and the predicate. The predicate helps decide whether a given
- insn matches the pattern. The constraint plays no role in this
- decision; instead, it controls various decisions in the case of an
- insn which does match.
-
- On CISC machines, the most common PREDICATE is
- `"general_operand"'. This function checks that the putative
- operand is either a constant, a register or a memory reference,
- and that it is valid for mode M.
-
- For an operand that must be a register, PREDICATE should be
- `"register_operand"'. Using `"general_operand"' would be valid,
- since the reload pass would copy any non-register operands through
- registers, but this would make GCC do extra work, it would prevent
- invariant operands (such as constant) from being removed from
- loops, and it would prevent the register allocator from doing the
- best possible job. On RISC machines, it is usually most efficient
- to allow PREDICATE to accept only objects that the constraints
- allow.
-
- For an operand that must be a constant, you must be sure to either
- use `"immediate_operand"' for PREDICATE, or make the instruction
- pattern's extra condition require a constant, or both. You cannot
- expect the constraints to do this work! If the constraints allow
- only constants, but the predicate allows something else, the
- compiler will crash when that case arises.
-
-`(match_scratch:M N CONSTRAINT)'
- This expression is also a placeholder for operand number N and
- indicates that operand must be a `scratch' or `reg' expression.
-
- When matching patterns, this is equivalent to
-
- (match_operand:M N "scratch_operand" PRED)
-
- but, when generating RTL, it produces a (`scratch':M) expression.
-
- If the last few expressions in a `parallel' are `clobber'
- expressions whose operands are either a hard register or
- `match_scratch', the combiner can add or delete them when
- necessary. *Note Side Effects::.
-
-`(match_dup N)'
- This expression is also a placeholder for operand number N. It is
- used when the operand needs to appear more than once in the insn.
-
- In construction, `match_dup' acts just like `match_operand': the
- operand is substituted into the insn being constructed. But in
- matching, `match_dup' behaves differently. It assumes that operand
- number N has already been determined by a `match_operand'
- appearing earlier in the recognition template, and it matches only
- an identical-looking expression.
-
- Note that `match_dup' should not be used to tell the compiler that
- a particular register is being used for two operands (example:
- `add' that adds one register to another; the second register is
- both an input operand and the output operand). Use a matching
- constraint (*note Simple Constraints::) for those. `match_dup' is
- for the cases where one operand is used in two places in the
- template, such as an instruction that computes both a quotient and
- a remainder, where the opcode takes two input operands but the RTL
- template has to refer to each of those twice; once for the
- quotient pattern and once for the remainder pattern.
-
-`(match_operator:M N PREDICATE [OPERANDS...])'
- This pattern is a kind of placeholder for a variable RTL expression
- code.
-
- When constructing an insn, it stands for an RTL expression whose
- expression code is taken from that of operand N, and whose
- operands are constructed from the patterns OPERANDS.
-
- When matching an expression, it matches an expression if the
- function PREDICATE returns nonzero on that expression _and_ the
- patterns OPERANDS match the operands of the expression.
-
- Suppose that the function `commutative_operator' is defined as
- follows, to match any expression whose operator is one of the
- commutative arithmetic operators of RTL and whose mode is MODE:
-
- int
- commutative_operator (x, mode)
- rtx x;
- enum machine_mode mode;
- {
- enum rtx_code code = GET_CODE (x);
- if (GET_MODE (x) != mode)
- return 0;
- return (GET_RTX_CLASS (code) == 'c'
- || code == EQ || code == NE);
- }
-
- Then the following pattern will match any RTL expression consisting
- of a commutative operator applied to two general operands:
-
- (match_operator:SI 3 "commutative_operator"
- [(match_operand:SI 1 "general_operand" "g")
- (match_operand:SI 2 "general_operand" "g")])
-
- Here the vector `[OPERANDS...]' contains two patterns because the
- expressions to be matched all contain two operands.
-
- When this pattern does match, the two operands of the commutative
- operator are recorded as operands 1 and 2 of the insn. (This is
- done by the two instances of `match_operand'.) Operand 3 of the
- insn will be the entire commutative expression: use `GET_CODE
- (operands[3])' to see which commutative operator was used.
-
- The machine mode M of `match_operator' works like that of
- `match_operand': it is passed as the second argument to the
- predicate function, and that function is solely responsible for
- deciding whether the expression to be matched "has" that mode.
-
- When constructing an insn, argument 3 of the gen-function will
- specify the operation (i.e. the expression code) for the
- expression to be made. It should be an RTL expression, whose
- expression code is copied into a new expression whose operands are
- arguments 1 and 2 of the gen-function. The subexpressions of
- argument 3 are not used; only its expression code matters.
-
- When `match_operator' is used in a pattern for matching an insn,
- it usually best if the operand number of the `match_operator' is
- higher than that of the actual operands of the insn. This improves
- register allocation because the register allocator often looks at
- operands 1 and 2 of insns to see if it can do register tying.
-
- There is no way to specify constraints in `match_operator'. The
- operand of the insn which corresponds to the `match_operator'
- never has any constraints because it is never reloaded as a whole.
- However, if parts of its OPERANDS are matched by `match_operand'
- patterns, those parts may have constraints of their own.
-
-`(match_op_dup:M N[OPERANDS...])'
- Like `match_dup', except that it applies to operators instead of
- operands. When constructing an insn, operand number N will be
- substituted at this point. But in matching, `match_op_dup' behaves
- differently. It assumes that operand number N has already been
- determined by a `match_operator' appearing earlier in the
- recognition template, and it matches only an identical-looking
- expression.
-
-`(match_parallel N PREDICATE [SUBPAT...])'
- This pattern is a placeholder for an insn that consists of a
- `parallel' expression with a variable number of elements. This
- expression should only appear at the top level of an insn pattern.
-
- When constructing an insn, operand number N will be substituted at
- this point. When matching an insn, it matches if the body of the
- insn is a `parallel' expression with at least as many elements as
- the vector of SUBPAT expressions in the `match_parallel', if each
- SUBPAT matches the corresponding element of the `parallel', _and_
- the function PREDICATE returns nonzero on the `parallel' that is
- the body of the insn. It is the responsibility of the predicate
- to validate elements of the `parallel' beyond those listed in the
- `match_parallel'.
-
- A typical use of `match_parallel' is to match load and store
- multiple expressions, which can contain a variable number of
- elements in a `parallel'. For example,
-
- (define_insn ""
- [(match_parallel 0 "load_multiple_operation"
- [(set (match_operand:SI 1 "gpc_reg_operand" "=r")
- (match_operand:SI 2 "memory_operand" "m"))
- (use (reg:SI 179))
- (clobber (reg:SI 179))])]
- ""
- "loadm 0,0,%1,%2")
-
- This example comes from `a29k.md'. The function
- `load_multiple_operation' is defined in `a29k.c' and checks that
- subsequent elements in the `parallel' are the same as the `set' in
- the pattern, except that they are referencing subsequent registers
- and memory locations.
-
- An insn that matches this pattern might look like:
-
- (parallel
- [(set (reg:SI 20) (mem:SI (reg:SI 100)))
- (use (reg:SI 179))
- (clobber (reg:SI 179))
- (set (reg:SI 21)
- (mem:SI (plus:SI (reg:SI 100)
- (const_int 4))))
- (set (reg:SI 22)
- (mem:SI (plus:SI (reg:SI 100)
- (const_int 8))))])
-
-`(match_par_dup N [SUBPAT...])'
- Like `match_op_dup', but for `match_parallel' instead of
- `match_operator'.
-
-`(match_insn PREDICATE)'
- Match a complete insn. Unlike the other `match_*' recognizers,
- `match_insn' does not take an operand number.
-
- The machine mode M of `match_insn' works like that of
- `match_operand': it is passed as the second argument to the
- predicate function, and that function is solely responsible for
- deciding whether the expression to be matched "has" that mode.
-
-`(match_insn2 N PREDICATE)'
- Match a complete insn.
-
- The machine mode M of `match_insn2' works like that of
- `match_operand': it is passed as the second argument to the
- predicate function, and that function is solely responsible for
- deciding whether the expression to be matched "has" that mode.
-
-
-\1f
-File: gccint.info, Node: Output Template, Next: Output Statement, Prev: RTL Template, Up: Machine Desc
-
-Output Templates and Operand Substitution
-=========================================
-
- The "output template" is a string which specifies how to output the
-assembler code for an instruction pattern. Most of the template is a
-fixed string which is output literally. The character `%' is used to
-specify where to substitute an operand; it can also be used to identify
-places where different variants of the assembler require different
-syntax.
-
- In the simplest case, a `%' followed by a digit N says to output
-operand N at that point in the string.
-
- `%' followed by a letter and a digit says to output an operand in an
-alternate fashion. Four letters have standard, built-in meanings
-described below. The machine description macro `PRINT_OPERAND' can
-define additional letters with nonstandard meanings.
-
- `%cDIGIT' can be used to substitute an operand that is a constant
-value without the syntax that normally indicates an immediate operand.
-
- `%nDIGIT' is like `%cDIGIT' except that the value of the constant is
-negated before printing.
-
- `%aDIGIT' can be used to substitute an operand as if it were a
-memory reference, with the actual operand treated as the address. This
-may be useful when outputting a "load address" instruction, because
-often the assembler syntax for such an instruction requires you to
-write the operand as if it were a memory reference.
-
- `%lDIGIT' is used to substitute a `label_ref' into a jump
-instruction.
-
- `%=' outputs a number which is unique to each instruction in the
-entire compilation. This is useful for making local labels to be
-referred to more than once in a single template that generates multiple
-assembler instructions.
-
- `%' followed by a punctuation character specifies a substitution that
-does not use an operand. Only one case is standard: `%%' outputs a `%'
-into the assembler code. Other nonstandard cases can be defined in the
-`PRINT_OPERAND' macro. You must also define which punctuation
-characters are valid with the `PRINT_OPERAND_PUNCT_VALID_P' macro.
-
- The template may generate multiple assembler instructions. Write
-the text for the instructions, with `\;' between them.
-
- When the RTL contains two operands which are required by constraint
-to match each other, the output template must refer only to the
-lower-numbered operand. Matching operands are not always identical,
-and the rest of the compiler arranges to put the proper RTL expression
-for printing into the lower-numbered operand.
-
- One use of nonstandard letters or punctuation following `%' is to
-distinguish between different assembler languages for the same machine;
-for example, Motorola syntax versus MIT syntax for the 68000. Motorola
-syntax requires periods in most opcode names, while MIT syntax does
-not. For example, the opcode `movel' in MIT syntax is `move.l' in
-Motorola syntax. The same file of patterns is used for both kinds of
-output syntax, but the character sequence `%.' is used in each place
-where Motorola syntax wants a period. The `PRINT_OPERAND' macro for
-Motorola syntax defines the sequence to output a period; the macro for
-MIT syntax defines it to do nothing.
-
- As a special case, a template consisting of the single character `#'
-instructs the compiler to first split the insn, and then output the
-resulting instructions separately. This helps eliminate redundancy in
-the output templates. If you have a `define_insn' that needs to emit
-multiple assembler instructions, and there is an matching `define_split'
-already defined, then you can simply use `#' as the output template
-instead of writing an output template that emits the multiple assembler
-instructions.
-
- If the macro `ASSEMBLER_DIALECT' is defined, you can use construct
-of the form `{option0|option1|option2}' in the templates. These
-describe multiple variants of assembler language syntax. *Note
-Instruction Output::.
-
-\1f
-File: gccint.info, Node: Output Statement, Next: Constraints, Prev: Output Template, Up: Machine Desc
-
-C Statements for Assembler Output
-=================================
-
- Often a single fixed template string cannot produce correct and
-efficient assembler code for all the cases that are recognized by a
-single instruction pattern. For example, the opcodes may depend on the
-kinds of operands; or some unfortunate combinations of operands may
-require extra machine instructions.
-
- If the output control string starts with a `@', then it is actually
-a series of templates, each on a separate line. (Blank lines and
-leading spaces and tabs are ignored.) The templates correspond to the
-pattern's constraint alternatives (*note Multi-Alternative::). For
-example, if a target machine has a two-address add instruction `addr'
-to add into a register and another `addm' to add a register to memory,
-you might write this pattern:
-
- (define_insn "addsi3"
- [(set (match_operand:SI 0 "general_operand" "=r,m")
- (plus:SI (match_operand:SI 1 "general_operand" "0,0")
- (match_operand:SI 2 "general_operand" "g,r")))]
- ""
- "@
- addr %2,%0
- addm %2,%0")
-
- If the output control string starts with a `*', then it is not an
-output template but rather a piece of C program that should compute a
-template. It should execute a `return' statement to return the
-template-string you want. Most such templates use C string literals,
-which require doublequote characters to delimit them. To include these
-doublequote characters in the string, prefix each one with `\'.
-
- If the output control string is written as a brace block instead of a
-double-quoted string, it is automatically assumed to be C code. In that
-case, it is not necessary to put in a leading asterisk, or to escape the
-doublequotes surrounding C string literals.
-
- The operands may be found in the array `operands', whose C data type
-is `rtx []'.
-
- It is very common to select different ways of generating assembler
-code based on whether an immediate operand is within a certain range.
-Be careful when doing this, because the result of `INTVAL' is an
-integer on the host machine. If the host machine has more bits in an
-`int' than the target machine has in the mode in which the constant
-will be used, then some of the bits you get from `INTVAL' will be
-superfluous. For proper results, you must carefully disregard the
-values of those bits.
-
- It is possible to output an assembler instruction and then go on to
-output or compute more of them, using the subroutine `output_asm_insn'.
-This receives two arguments: a template-string and a vector of
-operands. The vector may be `operands', or it may be another array of
-`rtx' that you declare locally and initialize yourself.
-
- When an insn pattern has multiple alternatives in its constraints,
-often the appearance of the assembler code is determined mostly by
-which alternative was matched. When this is so, the C code can test
-the variable `which_alternative', which is the ordinal number of the
-alternative that was actually satisfied (0 for the first, 1 for the
-second alternative, etc.).
-
- For example, suppose there are two opcodes for storing zero, `clrreg'
-for registers and `clrmem' for memory locations. Here is how a pattern
-could use `which_alternative' to choose between them:
-
- (define_insn ""
- [(set (match_operand:SI 0 "general_operand" "=r,m")
- (const_int 0))]
- ""
- {
- return (which_alternative == 0
- ? "clrreg %0" : "clrmem %0");
- })
-
- The example above, where the assembler code to generate was _solely_
-determined by the alternative, could also have been specified as
-follows, having the output control string start with a `@':
-
- (define_insn ""
- [(set (match_operand:SI 0 "general_operand" "=r,m")
- (const_int 0))]
- ""
- "@
- clrreg %0
- clrmem %0")
-
-\1f
-File: gccint.info, Node: Constraints, Next: Standard Names, Prev: Output Statement, Up: Machine Desc
-
-Operand Constraints
-===================
-
- Each `match_operand' in an instruction pattern can specify a
-constraint for the type of operands allowed. Constraints can say
-whether an operand may be in a register, and which kinds of register;
-whether the operand can be a memory reference, and which kinds of
-address; whether the operand may be an immediate constant, and which
-possible values it may have. Constraints can also require two operands
-to match.
-
-* Menu:
-
-* Simple Constraints:: Basic use of constraints.
-* Multi-Alternative:: When an insn has two alternative constraint-patterns.
-* Class Preferences:: Constraints guide which hard register to put things in.
-* Modifiers:: More precise control over effects of constraints.
-* Machine Constraints:: Existing constraints for some particular machines.
-
-\1f
-File: gccint.info, Node: Simple Constraints, Next: Multi-Alternative, Up: Constraints
-
-Simple Constraints
-------------------
-
- The simplest kind of constraint is a string full of letters, each of
-which describes one kind of operand that is permitted. Here are the
-letters that are allowed:
-
-whitespace
- Whitespace characters are ignored and can be inserted at any
- position except the first. This enables each alternative for
- different operands to be visually aligned in the machine
- description even if they have different number of constraints and
- modifiers.
-
-`m'
- A memory operand is allowed, with any kind of address that the
- machine supports in general.
-
-`o'
- A memory operand is allowed, but only if the address is
- "offsettable". This means that adding a small integer (actually,
- the width in bytes of the operand, as determined by its machine
- mode) may be added to the address and the result is also a valid
- memory address.
-
- For example, an address which is constant is offsettable; so is an
- address that is the sum of a register and a constant (as long as a
- slightly larger constant is also within the range of
- address-offsets supported by the machine); but an autoincrement or
- autodecrement address is not offsettable. More complicated
- indirect/indexed addresses may or may not be offsettable depending
- on the other addressing modes that the machine supports.
-
- Note that in an output operand which can be matched by another
- operand, the constraint letter `o' is valid only when accompanied
- by both `<' (if the target machine has predecrement addressing)
- and `>' (if the target machine has preincrement addressing).
-
-`V'
- A memory operand that is not offsettable. In other words,
- anything that would fit the `m' constraint but not the `o'
- constraint.
-
-`<'
- A memory operand with autodecrement addressing (either
- predecrement or postdecrement) is allowed.
-
-`>'
- A memory operand with autoincrement addressing (either
- preincrement or postincrement) is allowed.
-
-`r'
- A register operand is allowed provided that it is in a general
- register.
-
-`i'
- An immediate integer operand (one with constant value) is allowed.
- This includes symbolic constants whose values will be known only at
- assembly time.
-
-`n'
- An immediate integer operand with a known numeric value is allowed.
- Many systems cannot support assembly-time constants for operands
- less than a word wide. Constraints for these operands should use
- `n' rather than `i'.
-
-`I', `J', `K', ... `P'
- Other letters in the range `I' through `P' may be defined in a
- machine-dependent fashion to permit immediate integer operands with
- explicit integer values in specified ranges. For example, on the
- 68000, `I' is defined to stand for the range of values 1 to 8.
- This is the range permitted as a shift count in the shift
- instructions.
-
-`E'
- An immediate floating operand (expression code `const_double') is
- allowed, but only if the target floating point format is the same
- as that of the host machine (on which the compiler is running).
-
-`F'
- An immediate floating operand (expression code `const_double') is
- allowed.
-
-`G', `H'
- `G' and `H' may be defined in a machine-dependent fashion to
- permit immediate floating operands in particular ranges of values.
-
-`s'
- An immediate integer operand whose value is not an explicit
- integer is allowed.
-
- This might appear strange; if an insn allows a constant operand
- with a value not known at compile time, it certainly must allow
- any known value. So why use `s' instead of `i'? Sometimes it
- allows better code to be generated.
-
- For example, on the 68000 in a fullword instruction it is possible
- to use an immediate operand; but if the immediate value is between
- -128 and 127, better code results from loading the value into a
- register and using the register. This is because the load into
- the register can be done with a `moveq' instruction. We arrange
- for this to happen by defining the letter `K' to mean "any integer
- outside the range -128 to 127", and then specifying `Ks' in the
- operand constraints.
-
-`g'
- Any register, memory or immediate integer operand is allowed,
- except for registers that are not general registers.
-
-`X'
- Any operand whatsoever is allowed, even if it does not satisfy
- `general_operand'. This is normally used in the constraint of a
- `match_scratch' when certain alternatives will not actually
- require a scratch register.
-
-`0', `1', `2', ... `9'
- An operand that matches the specified operand number is allowed.
- If a digit is used together with letters within the same
- alternative, the digit should come last.
-
- This number is allowed to be more than a single digit. If multiple
- digits are encountered consecutavely, they are interpreted as a
- single decimal integer. There is scant chance for ambiguity,
- since to-date it has never been desirable that `10' be interpreted
- as matching either operand 1 _or_ operand 0. Should this be
- desired, one can use multiple alternatives instead.
-
- This is called a "matching constraint" and what it really means is
- that the assembler has only a single operand that fills two roles
- considered separate in the RTL insn. For example, an add insn has
- two input operands and one output operand in the RTL, but on most
- CISC machines an add instruction really has only two operands, one
- of them an input-output operand:
-
- addl #35,r12
-
- Matching constraints are used in these circumstances. More
- precisely, the two operands that match must include one input-only
- operand and one output-only operand. Moreover, the digit must be a
- smaller number than the number of the operand that uses it in the
- constraint.
-
- For operands to match in a particular case usually means that they
- are identical-looking RTL expressions. But in a few special cases
- specific kinds of dissimilarity are allowed. For example, `*x' as
- an input operand will match `*x++' as an output operand. For
- proper results in such cases, the output template should always
- use the output-operand's number when printing the operand.
-
-`p'
- An operand that is a valid memory address is allowed. This is for
- "load address" and "push address" instructions.
-
- `p' in the constraint must be accompanied by `address_operand' as
- the predicate in the `match_operand'. This predicate interprets
- the mode specified in the `match_operand' as the mode of the memory
- reference for which the address would be valid.
-
-OTHER-LETTERS
- Other letters can be defined in machine-dependent fashion to stand
- for particular classes of registers or other arbitrary operand
- types. `d', `a' and `f' are defined on the 68000/68020 to stand
- for data, address and floating point registers.
-
- The machine description macro `REG_CLASS_FROM_LETTER' has first
- cut at the otherwise unused letters. If it evaluates to `NO_REGS',
- then `EXTRA_CONSTRAINT' is evaluated.
-
- A typical use for `EXTRA_CONSTRANT' would be to distinguish certain
- types of memory references that affect other insn operands.
-
- In order to have valid assembler code, each operand must satisfy its
-constraint. But a failure to do so does not prevent the pattern from
-applying to an insn. Instead, it directs the compiler to modify the
-code so that the constraint will be satisfied. Usually this is done by
-copying an operand into a register.
-
- Contrast, therefore, the two instruction patterns that follow:
-
- (define_insn ""
- [(set (match_operand:SI 0 "general_operand" "=r")
- (plus:SI (match_dup 0)
- (match_operand:SI 1 "general_operand" "r")))]
- ""
- "...")
-
-which has two operands, one of which must appear in two places, and
-
- (define_insn ""
- [(set (match_operand:SI 0 "general_operand" "=r")
- (plus:SI (match_operand:SI 1 "general_operand" "0")
- (match_operand:SI 2 "general_operand" "r")))]
- ""
- "...")
-
-which has three operands, two of which are required by a constraint to
-be identical. If we are considering an insn of the form
-
- (insn N PREV NEXT
- (set (reg:SI 3)
- (plus:SI (reg:SI 6) (reg:SI 109)))
- ...)
-
-the first pattern would not apply at all, because this insn does not
-contain two identical subexpressions in the right place. The pattern
-would say, "That does not look like an add instruction; try other
-patterns." The second pattern would say, "Yes, that's an add
-instruction, but there is something wrong with it." It would direct
-the reload pass of the compiler to generate additional insns to make
-the constraint true. The results might look like this:
-
- (insn N2 PREV N
- (set (reg:SI 3) (reg:SI 6))
- ...)
-
- (insn N N2 NEXT
- (set (reg:SI 3)
- (plus:SI (reg:SI 3) (reg:SI 109)))
- ...)
-
- It is up to you to make sure that each operand, in each pattern, has
-constraints that can handle any RTL expression that could be present for
-that operand. (When multiple alternatives are in use, each pattern
-must, for each possible combination of operand expressions, have at
-least one alternative which can handle that combination of operands.)
-The constraints don't need to _allow_ any possible operand--when this is
-the case, they do not constrain--but they must at least point the way to
-reloading any possible operand so that it will fit.
-
- * If the constraint accepts whatever operands the predicate permits,
- there is no problem: reloading is never necessary for this operand.
-
- For example, an operand whose constraints permit everything except
- registers is safe provided its predicate rejects registers.
-
- An operand whose predicate accepts only constant values is safe
- provided its constraints include the letter `i'. If any possible
- constant value is accepted, then nothing less than `i' will do; if
- the predicate is more selective, then the constraints may also be
- more selective.
-
- * Any operand expression can be reloaded by copying it into a
- register. So if an operand's constraints allow some kind of
- register, it is certain to be safe. It need not permit all
- classes of registers; the compiler knows how to copy a register
- into another register of the proper class in order to make an
- instruction valid.
-
- * A nonoffsettable memory reference can be reloaded by copying the
- address into a register. So if the constraint uses the letter
- `o', all memory references are taken care of.
-
- * A constant operand can be reloaded by allocating space in memory to
- hold it as preinitialized data. Then the memory reference can be
- used in place of the constant. So if the constraint uses the
- letters `o' or `m', constant operands are not a problem.
-
- * If the constraint permits a constant and a pseudo register used in
- an insn was not allocated to a hard register and is equivalent to
- a constant, the register will be replaced with the constant. If
- the predicate does not permit a constant and the insn is
- re-recognized for some reason, the compiler will crash. Thus the
- predicate must always recognize any objects allowed by the
- constraint.
-
- If the operand's predicate can recognize registers, but the
-constraint does not permit them, it can make the compiler crash. When
-this operand happens to be a register, the reload pass will be stymied,
-because it does not know how to copy a register temporarily into memory.
-
- If the predicate accepts a unary operator, the constraint applies to
-the operand. For example, the MIPS processor at ISA level 3 supports an
-instruction which adds two registers in `SImode' to produce a `DImode'
-result, but only if the registers are correctly sign extended. This
-predicate for the input operands accepts a `sign_extend' of an `SImode'
-register. Write the constraint to indicate the type of register that
-is required for the operand of the `sign_extend'.
-
-\1f
-File: gccint.info, Node: Multi-Alternative, Next: Class Preferences, Prev: Simple Constraints, Up: Constraints
-
-Multiple Alternative Constraints
---------------------------------
-
- Sometimes a single instruction has multiple alternative sets of
-possible operands. For example, on the 68000, a logical-or instruction
-can combine register or an immediate value into memory, or it can
-combine any kind of operand into a register; but it cannot combine one
-memory location into another.
-
- These constraints are represented as multiple alternatives. An
-alternative can be described by a series of letters for each operand.
-The overall constraint for an operand is made from the letters for this
-operand from the first alternative, a comma, the letters for this
-operand from the second alternative, a comma, and so on until the last
-alternative. Here is how it is done for fullword logical-or on the
-68000:
-
- (define_insn "iorsi3"
- [(set (match_operand:SI 0 "general_operand" "=m,d")
- (ior:SI (match_operand:SI 1 "general_operand" "%0,0")
- (match_operand:SI 2 "general_operand" "dKs,dmKs")))]
- ...)
-
- The first alternative has `m' (memory) for operand 0, `0' for
-operand 1 (meaning it must match operand 0), and `dKs' for operand 2.
-The second alternative has `d' (data register) for operand 0, `0' for
-operand 1, and `dmKs' for operand 2. The `=' and `%' in the
-constraints apply to all the alternatives; their meaning is explained
-in the next section (*note Class Preferences::).
-
- If all the operands fit any one alternative, the instruction is
-valid. Otherwise, for each alternative, the compiler counts how many
-instructions must be added to copy the operands so that that
-alternative applies. The alternative requiring the least copying is
-chosen. If two alternatives need the same amount of copying, the one
-that comes first is chosen. These choices can be altered with the `?'
-and `!' characters:
-
-`?'
- Disparage slightly the alternative that the `?' appears in, as a
- choice when no alternative applies exactly. The compiler regards
- this alternative as one unit more costly for each `?' that appears
- in it.
-
-`!'
- Disparage severely the alternative that the `!' appears in. This
- alternative can still be used if it fits without reloading, but if
- reloading is needed, some other alternative will be used.
-
- When an insn pattern has multiple alternatives in its constraints,
-often the appearance of the assembler code is determined mostly by which
-alternative was matched. When this is so, the C code for writing the
-assembler code can use the variable `which_alternative', which is the
-ordinal number of the alternative that was actually satisfied (0 for
-the first, 1 for the second alternative, etc.). *Note Output
-Statement::.
-
-\1f
-File: gccint.info, Node: Class Preferences, Next: Modifiers, Prev: Multi-Alternative, Up: Constraints
-
-Register Class Preferences
---------------------------
-
- The operand constraints have another function: they enable the
-compiler to decide which kind of hardware register a pseudo register is
-best allocated to. The compiler examines the constraints that apply to
-the insns that use the pseudo register, looking for the
-machine-dependent letters such as `d' and `a' that specify classes of
-registers. The pseudo register is put in whichever class gets the most
-"votes". The constraint letters `g' and `r' also vote: they vote in
-favor of a general register. The machine description says which
-registers are considered general.
-
- Of course, on some machines all registers are equivalent, and no
-register classes are defined. Then none of this complexity is relevant.
-
-\1f
-File: gccint.info, Node: Modifiers, Next: Machine Constraints, Prev: Class Preferences, Up: Constraints
-
-Constraint Modifier Characters
-------------------------------
-
- Here are constraint modifier characters.
-
-`='
- Means that this operand is write-only for this instruction: the
- previous value is discarded and replaced by output data.
-
-`+'
- Means that this operand is both read and written by the
- instruction.
-
- When the compiler fixes up the operands to satisfy the constraints,
- it needs to know which operands are inputs to the instruction and
- which are outputs from it. `=' identifies an output; `+'
- identifies an operand that is both input and output; all other
- operands are assumed to be input only.
-
- If you specify `=' or `+' in a constraint, you put it in the first
- character of the constraint string.
-
-`&'
- Means (in a particular alternative) that this operand is an
- "earlyclobber" operand, which is modified before the instruction is
- finished using the input operands. Therefore, this operand may
- not lie in a register that is used as an input operand or as part
- of any memory address.
-
- `&' applies only to the alternative in which it is written. In
- constraints with multiple alternatives, sometimes one alternative
- requires `&' while others do not. See, for example, the `movdf'
- insn of the 68000.
-
- An input operand can be tied to an earlyclobber operand if its only
- use as an input occurs before the early result is written. Adding
- alternatives of this form often allows GCC to produce better code
- when only some of the inputs can be affected by the earlyclobber.
- See, for example, the `mulsi3' insn of the ARM.
-
- `&' does not obviate the need to write `='.
-
-`%'
- Declares the instruction to be commutative for this operand and the
- following operand. This means that the compiler may interchange
- the two operands if that is the cheapest way to make all operands
- fit the constraints. This is often used in patterns for addition
- instructions that really have only two operands: the result must
- go in one of the arguments. Here for example, is how the 68000
- halfword-add instruction is defined:
-
- (define_insn "addhi3"
- [(set (match_operand:HI 0 "general_operand" "=m,r")
- (plus:HI (match_operand:HI 1 "general_operand" "%0,0")
- (match_operand:HI 2 "general_operand" "di,g")))]
- ...)
-
-`#'
- Says that all following characters, up to the next comma, are to be
- ignored as a constraint. They are significant only for choosing
- register preferences.
-
-`*'
- Says that the following character should be ignored when choosing
- register preferences. `*' has no effect on the meaning of the
- constraint as a constraint, and no effect on reloading.
-
- Here is an example: the 68000 has an instruction to sign-extend a
- halfword in a data register, and can also sign-extend a value by
- copying it into an address register. While either kind of
- register is acceptable, the constraints on an address-register
- destination are less strict, so it is best if register allocation
- makes an address register its goal. Therefore, `*' is used so
- that the `d' constraint letter (for data register) is ignored when
- computing register preferences.
-
- (define_insn "extendhisi2"
- [(set (match_operand:SI 0 "general_operand" "=*d,a")
- (sign_extend:SI
- (match_operand:HI 1 "general_operand" "0,g")))]
- ...)
-
+++ /dev/null
-This is doc/gccint.info, produced by makeinfo version 4.5 from
-doc/gccint.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* gccint: (gccint). Internals of the GNU Compiler Collection.
-END-INFO-DIR-ENTRY
- This file documents the internals of the GNU compilers.
-
- Published by the Free Software Foundation
-59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
-\1f
-File: gccint.info, Node: Machine Constraints, Prev: Modifiers, Up: Constraints
-
-Constraints for Particular Machines
------------------------------------
-
- Whenever possible, you should use the general-purpose constraint
-letters in `asm' arguments, since they will convey meaning more readily
-to people reading your code. Failing that, use the constraint letters
-that usually have very similar meanings across architectures. The most
-commonly used constraints are `m' and `r' (for memory and
-general-purpose registers respectively; *note Simple Constraints::), and
-`I', usually the letter indicating the most common immediate-constant
-format.
-
- For each machine architecture, the `config/MACHINE/MACHINE.h' file
-defines additional constraints. These constraints are used by the
-compiler itself for instruction generation, as well as for `asm'
-statements; therefore, some of the constraints are not particularly
-interesting for `asm'. The constraints are defined through these
-macros:
-
-`REG_CLASS_FROM_LETTER'
- Register class constraints (usually lower case).
-
-`CONST_OK_FOR_LETTER_P'
- Immediate constant constraints, for non-floating point constants of
- word size or smaller precision (usually upper case).
-
-`CONST_DOUBLE_OK_FOR_LETTER_P'
- Immediate constant constraints, for all floating point constants
- and for constants of greater than word size precision (usually
- upper case).
-
-`EXTRA_CONSTRAINT'
- Special cases of registers or memory. This macro is not required,
- and is only defined for some machines.
-
- Inspecting these macro definitions in the compiler source for your
-machine is the best way to be certain you have the right constraints.
-However, here is a summary of the machine-dependent constraints
-available on some particular machines.
-
-_ARM family--`arm.h'_
-
- `f'
- Floating-point register
-
- `F'
- One of the floating-point constants 0.0, 0.5, 1.0, 2.0, 3.0,
- 4.0, 5.0 or 10.0
-
- `G'
- Floating-point constant that would satisfy the constraint `F'
- if it were negated
-
- `I'
- Integer that is valid as an immediate operand in a data
- processing instruction. That is, an integer in the range 0
- to 255 rotated by a multiple of 2
-
- `J'
- Integer in the range -4095 to 4095
-
- `K'
- Integer that satisfies constraint `I' when inverted (ones
- complement)
-
- `L'
- Integer that satisfies constraint `I' when negated (twos
- complement)
-
- `M'
- Integer in the range 0 to 32
-
- `Q'
- A memory reference where the exact address is in a single
- register (``m'' is preferable for `asm' statements)
-
- `R'
- An item in the constant pool
-
- `S'
- A symbol in the text segment of the current file
-
-_AMD 29000 family--`a29k.h'_
-
- `l'
- Local register 0
-
- `b'
- Byte Pointer (`BP') register
-
- `q'
- `Q' register
-
- `h'
- Special purpose register
-
- `A'
- First accumulator register
-
- `a'
- Other accumulator register
-
- `f'
- Floating point register
-
- `I'
- Constant greater than 0, less than 0x100
-
- `J'
- Constant greater than 0, less than 0x10000
-
- `K'
- Constant whose high 24 bits are on (1)
-
- `L'
- 16-bit constant whose high 8 bits are on (1)
-
- `M'
- 32-bit constant whose high 16 bits are on (1)
-
- `N'
- 32-bit negative constant that fits in 8 bits
-
- `O'
- The constant 0x80000000 or, on the 29050, any 32-bit constant
- whose low 16 bits are 0.
-
- `P'
- 16-bit negative constant that fits in 8 bits
-
- `G'
- `H'
- A floating point constant (in `asm' statements, use the
- machine independent `E' or `F' instead)
-
-_AVR family--`avr.h'_
-
- `l'
- Registers from r0 to r15
-
- `a'
- Registers from r16 to r23
-
- `d'
- Registers from r16 to r31
-
- `w'
- Registers from r24 to r31. These registers can be used in
- `adiw' command
-
- `e'
- Pointer register (r26-r31)
-
- `b'
- Base pointer register (r28-r31)
-
- `q'
- Stack pointer register (SPH:SPL)
-
- `t'
- Temporary register r0
-
- `x'
- Register pair X (r27:r26)
-
- `y'
- Register pair Y (r29:r28)
-
- `z'
- Register pair Z (r31:r30)
-
- `I'
- Constant greater than -1, less than 64
-
- `J'
- Constant greater than -64, less than 1
-
- `K'
- Constant integer 2
-
- `L'
- Constant integer 0
-
- `M'
- Constant that fits in 8 bits
-
- `N'
- Constant integer -1
-
- `O'
- Constant integer 8, 16, or 24
-
- `P'
- Constant integer 1
-
- `G'
- A floating point constant 0.0
-
-_IBM RS6000--`rs6000.h'_
-
- `b'
- Address base register
-
- `f'
- Floating point register
-
- `h'
- `MQ', `CTR', or `LINK' register
-
- `q'
- `MQ' register
-
- `c'
- `CTR' register
-
- `l'
- `LINK' register
-
- `x'
- `CR' register (condition register) number 0
-
- `y'
- `CR' register (condition register)
-
- `z'
- `FPMEM' stack memory for FPR-GPR transfers
-
- `I'
- Signed 16-bit constant
-
- `J'
- Unsigned 16-bit constant shifted left 16 bits (use `L'
- instead for `SImode' constants)
-
- `K'
- Unsigned 16-bit constant
-
- `L'
- Signed 16-bit constant shifted left 16 bits
-
- `M'
- Constant larger than 31
-
- `N'
- Exact power of 2
-
- `O'
- Zero
-
- `P'
- Constant whose negation is a signed 16-bit constant
-
- `G'
- Floating point constant that can be loaded into a register
- with one instruction per word
-
- `Q'
- Memory operand that is an offset from a register (`m' is
- preferable for `asm' statements)
-
- `R'
- AIX TOC entry
-
- `S'
- Constant suitable as a 64-bit mask operand
-
- `T'
- Constant suitable as a 32-bit mask operand
-
- `U'
- System V Release 4 small data area reference
-
-_Intel 386--`i386.h'_
-
- `q'
- `a', `b', `c', or `d' register for the i386. For x86-64 it
- is equivalent to `r' class. (for 8-bit instructions that do
- not use upper halves)
-
- `Q'
- `a', `b', `c', or `d' register. (for 8-bit instructions, that
- do use upper halves)
-
- `R'
- Legacy register--equivalent to `r' class in i386 mode. (for
- non-8-bit registers used together with 8-bit upper halves in
- a single instruction)
-
- `A'
- Specifies the `a' or `d' registers. This is primarily useful
- for 64-bit integer values (when in 32-bit mode) intended to
- be returned with the `d' register holding the most
- significant bits and the `a' register holding the least
- significant bits.
-
- `f'
- Floating point register
-
- `t'
- First (top of stack) floating point register
-
- `u'
- Second floating point register
-
- `a'
- `a' register
-
- `b'
- `b' register
-
- `c'
- `c' register
-
- `d'
- `d' register
-
- `D'
- `di' register
-
- `S'
- `si' register
-
- `x'
- `xmm' SSE register
-
- `y'
- MMX register
-
- `I'
- Constant in range 0 to 31 (for 32-bit shifts)
-
- `J'
- Constant in range 0 to 63 (for 64-bit shifts)
-
- `K'
- `0xff'
-
- `L'
- `0xffff'
-
- `M'
- 0, 1, 2, or 3 (shifts for `lea' instruction)
-
- `N'
- Constant in range 0 to 255 (for `out' instruction)
-
- `Z'
- Constant in range 0 to `0xffffffff' or symbolic reference
- known to fit specified range. (for using immediates in zero
- extending 32-bit to 64-bit x86-64 instructions)
-
- `e'
- Constant in range -2147483648 to 2147483647 or symbolic
- reference known to fit specified range. (for using
- immediates in 64-bit x86-64 instructions)
-
- `G'
- Standard 80387 floating point constant
-
-_Intel 960--`i960.h'_
-
- `f'
- Floating point register (`fp0' to `fp3')
-
- `l'
- Local register (`r0' to `r15')
-
- `b'
- Global register (`g0' to `g15')
-
- `d'
- Any local or global register
-
- `I'
- Integers from 0 to 31
-
- `J'
- 0
-
- `K'
- Integers from -31 to 0
-
- `G'
- Floating point 0
-
- `H'
- Floating point 1
-
-_MIPS--`mips.h'_
-
- `d'
- General-purpose integer register
-
- `f'
- Floating-point register (if available)
-
- `h'
- `Hi' register
-
- `l'
- `Lo' register
-
- `x'
- `Hi' or `Lo' register
-
- `y'
- General-purpose integer register
-
- `z'
- Floating-point status register
-
- `I'
- Signed 16-bit constant (for arithmetic instructions)
-
- `J'
- Zero
-
- `K'
- Zero-extended 16-bit constant (for logic instructions)
-
- `L'
- Constant with low 16 bits zero (can be loaded with `lui')
-
- `M'
- 32-bit constant which requires two instructions to load (a
- constant which is not `I', `K', or `L')
-
- `N'
- Negative 16-bit constant
-
- `O'
- Exact power of two
-
- `P'
- Positive 16-bit constant
-
- `G'
- Floating point zero
-
- `Q'
- Memory reference that can be loaded with more than one
- instruction (`m' is preferable for `asm' statements)
-
- `R'
- Memory reference that can be loaded with one instruction (`m'
- is preferable for `asm' statements)
-
- `S'
- Memory reference in external OSF/rose PIC format (`m' is
- preferable for `asm' statements)
-
-_Motorola 680x0--`m68k.h'_
-
- `a'
- Address register
-
- `d'
- Data register
-
- `f'
- 68881 floating-point register, if available
-
- `x'
- Sun FPA (floating-point) register, if available
-
- `y'
- First 16 Sun FPA registers, if available
-
- `I'
- Integer in the range 1 to 8
-
- `J'
- 16-bit signed number
-
- `K'
- Signed number whose magnitude is greater than 0x80
-
- `L'
- Integer in the range -8 to -1
-
- `M'
- Signed number whose magnitude is greater than 0x100
-
- `G'
- Floating point constant that is not a 68881 constant
-
- `H'
- Floating point constant that can be used by Sun FPA
-
-_Motorola 68HC11 & 68HC12 families--`m68hc11.h'_
-
- `a'
- Register 'a'
-
- `b'
- Register 'b'
-
- `d'
- Register 'd'
-
- `q'
- An 8-bit register
-
- `t'
- Temporary soft register _.tmp
-
- `u'
- A soft register _.d1 to _.d31
-
- `w'
- Stack pointer register
-
- `x'
- Register 'x'
-
- `y'
- Register 'y'
-
- `z'
- Pseudo register 'z' (replaced by 'x' or 'y' at the end)
-
- `A'
- An address register: x, y or z
-
- `B'
- An address register: x or y
-
- `D'
- Register pair (x:d) to form a 32-bit value
-
- `L'
- Constants in the range -65536 to 65535
-
- `M'
- Constants whose 16-bit low part is zero
-
- `N'
- Constant integer 1 or -1
-
- `O'
- Constant integer 16
-
- `P'
- Constants in the range -8 to 2
-
-
-_SPARC--`sparc.h'_
-
- `f'
- Floating-point register that can hold 32- or 64-bit values.
-
- `e'
- Floating-point register that can hold 64- or 128-bit values.
-
- `I'
- Signed 13-bit constant
-
- `J'
- Zero
-
- `K'
- 32-bit constant with the low 12 bits clear (a constant that
- can be loaded with the `sethi' instruction)
-
- `L'
- A constant in the range supported by `movcc' instructions
-
- `M'
- A constant in the range supported by `movrcc' instructions
-
- `N'
- Same as `K', except that it verifies that bits that are not
- in the lower 32-bit range are all zero. Must be used instead
- of `K' for modes wider than `SImode'
-
- `G'
- Floating-point zero
-
- `H'
- Signed 13-bit constant, sign-extended to 32 or 64 bits
-
- `Q'
- Floating-point constant whose integral representation can be
- moved into an integer register using a single sethi
- instruction
-
- `R'
- Floating-point constant whose integral representation can be
- moved into an integer register using a single mov instruction
-
- `S'
- Floating-point constant whose integral representation can be
- moved into an integer register using a high/lo_sum
- instruction sequence
-
- `T'
- Memory address aligned to an 8-byte boundary
-
- `U'
- Even register
-
- `W'
- Memory address for `e' constraint registers.
-
-
-_TMS320C3x/C4x--`c4x.h'_
-
- `a'
- Auxiliary (address) register (ar0-ar7)
-
- `b'
- Stack pointer register (sp)
-
- `c'
- Standard (32-bit) precision integer register
-
- `f'
- Extended (40-bit) precision register (r0-r11)
-
- `k'
- Block count register (bk)
-
- `q'
- Extended (40-bit) precision low register (r0-r7)
-
- `t'
- Extended (40-bit) precision register (r0-r1)
-
- `u'
- Extended (40-bit) precision register (r2-r3)
-
- `v'
- Repeat count register (rc)
-
- `x'
- Index register (ir0-ir1)
-
- `y'
- Status (condition code) register (st)
-
- `z'
- Data page register (dp)
-
- `G'
- Floating-point zero
-
- `H'
- Immediate 16-bit floating-point constant
-
- `I'
- Signed 16-bit constant
-
- `J'
- Signed 8-bit constant
-
- `K'
- Signed 5-bit constant
-
- `L'
- Unsigned 16-bit constant
-
- `M'
- Unsigned 8-bit constant
-
- `N'
- Ones complement of unsigned 16-bit constant
-
- `O'
- High 16-bit constant (32-bit constant with 16 LSBs zero)
-
- `Q'
- Indirect memory reference with signed 8-bit or index register
- displacement
-
- `R'
- Indirect memory reference with unsigned 5-bit displacement
-
- `S'
- Indirect memory reference with 1 bit or index register
- displacement
-
- `T'
- Direct memory reference
-
- `U'
- Symbolic address
-
-
-_S/390 and zSeries--`s390.h'_
-
- `a'
- Address register (general purpose register except r0)
-
- `d'
- Data register (arbitrary general purpose register)
-
- `f'
- Floating-point register
-
- `I'
- Unsigned 8-bit constant (0-255)
-
- `J'
- Unsigned 12-bit constant (0-4095)
-
- `K'
- Signed 16-bit constant (-32768-32767)
-
- `L'
- Unsigned 16-bit constant (0-65535)
-
- `Q'
- Memory reference without index register
-
- `S'
- Symbolic constant suitable for use with the `larl' instruction
-
-
-_Xstormy16--`stormy16.h'_
-
- `a'
- Register r0.
-
- `b'
- Register r1.
-
- `c'
- Register r2.
-
- `d'
- Register r8.
-
- `e'
- Registers r0 through r7.
-
- `t'
- Registers r0 and r1.
-
- `y'
- The carry register.
-
- `z'
- Registers r8 and r9.
-
- `I'
- A constant between 0 and 3 inclusive.
-
- `J'
- A constant that has exactly one bit set.
-
- `K'
- A constant that has exactly one bit clear.
-
- `L'
- A constant between 0 and 255 inclusive.
-
- `M'
- A constant between -255 and 0 inclusive.
-
- `N'
- A constant between -3 and 0 inclusive.
-
- `O'
- A constant between 1 and 4 inclusive.
-
- `P'
- A constant between -4 and -1 inclusive.
-
- `Q'
- A memory reference that is a stack push.
-
- `R'
- A memory reference that is a stack pop.
-
- `S'
- A memory reference that refers to an constant address of
- known value.
-
- `T'
- The register indicated by Rx (not implemented yet).
-
- `U'
- A constant that is not between 2 and 15 inclusive.
-
-
-_Xtensa--`xtensa.h'_
-
- `a'
- General-purpose 32-bit register
-
- `b'
- One-bit boolean register
-
- `A'
- MAC16 40-bit accumulator register
-
- `I'
- Signed 12-bit integer constant, for use in MOVI instructions
-
- `J'
- Signed 8-bit integer constant, for use in ADDI instructions
-
- `K'
- Integer constant valid for BccI instructions
-
- `L'
- Unsigned constant valid for BccUI instructions
-
-
-
+++ /dev/null
-This is g77.info, produced by makeinfo version 4.5 from g77.texi.
-
-INFO-DIR-SECTION Programming
-START-INFO-DIR-ENTRY
-* g77: (g77). The GNU Fortran compiler.
-END-INFO-DIR-ENTRY
- This file documents the use and the internals of the GNU Fortran
-(`g77') compiler. It corresponds to the GCC-3.2.3 version of `g77'.
-
- Published by the Free Software Foundation 59 Temple Place - Suite 330
-Boston, MA 02111-1307 USA
-
- Copyright (C) 1995,1996,1997,1998,1999,2000,2001,2002 Free Software
-Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
-under the terms of the GNU Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being "GNU General Public License" and "Funding Free
-Software", the Front-Cover texts being (a) (see below), and with the
-Back-Cover Texts being (b) (see below). A copy of the license is
-included in the section entitled "GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
-
- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
-funds for GNU development.
-
- Contributed by James Craig Burley (<craig@jcb-sc.com>). Inspired by
-a first pass at translating `g77-0.5.16/f/DOC' that was contributed to
-Craig by David Ronis (<ronis@onsager.chem.mcgill.ca>).
-
-\1f
-Indirect:
-g77.info-1: 1460
-g77.info-2: 49509
-g77.info-3: 98817
-g77.info-4: 124552
-g77.info-5: 176715
-g77.info-6: 225206
-g77.info-7: 270209
-g77.info-8: 319613
-g77.info-9: 369073
-g77.info-10: 418640
-g77.info-11: 463040
-g77.info-12: 512588
-g77.info-13: 562579
-g77.info-14: 609603
-g77.info-15: 653767
-g77.info-16: 701448
-g77.info-17: 751000
-g77.info-18: 799364
-g77.info-19: 841909
-g77.info-20: 885662
-g77.info-21: 904652
-\1f
-Tag Table:
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-Node: NAMELIST\7f257925
-Node: DOUBLE COMPLEX\7f258676
-Node: Control Statements\7f258930
-Node: DO WHILE\7f259422
-Node: END DO\7f259727
-Node: Construct Names\7f260734
-Node: CYCLE and EXIT\7f261474
-Node: Functions and Subroutines\7f264238
-Node: %VAL()\7f264884
-Node: %REF()\7f266248
-Node: %DESCR()\7f268076
-Node: Generics and Specifics\7f270209
-Node: REAL() and AIMAG() of Complex\7f277411
-Node: CMPLX() of DOUBLE PRECISION\7f279244
-Node: MIL-STD 1753\7f280970
-Node: f77/f2c Intrinsics\7f281312
-Node: Table of Intrinsic Functions\7f281882
-Node: Abort Intrinsic\7f298594
-Node: Abs Intrinsic\7f298858
-Node: Access Intrinsic\7f299721
-Node: AChar Intrinsic\7f300557
-Node: ACos Intrinsic\7f301079
-Node: AdjustL Intrinsic\7f301540
-Node: AdjustR Intrinsic\7f301865
-Node: AImag Intrinsic\7f302191
-Node: AInt Intrinsic\7f302996
-Node: Alarm Intrinsic\7f303624
-Node: All Intrinsic\7f304456
-Node: Allocated Intrinsic\7f304768
-Node: ALog Intrinsic\7f305097
-Node: ALog10 Intrinsic\7f305487
-Node: AMax0 Intrinsic\7f305885
-Node: AMax1 Intrinsic\7f306370
-Node: AMin0 Intrinsic\7f306823
-Node: AMin1 Intrinsic\7f307307
-Node: AMod Intrinsic\7f307759
-Node: And Intrinsic\7f308185
-Node: ANInt Intrinsic\7f308691
-Node: Any Intrinsic\7f309455
-Node: ASin Intrinsic\7f309762
-Node: Associated Intrinsic\7f310220
-Node: ATan Intrinsic\7f310554
-Node: ATan2 Intrinsic\7f311020
-Node: BesJ0 Intrinsic\7f311571
-Node: BesJ1 Intrinsic\7f312032
-Node: BesJN Intrinsic\7f312493
-Node: BesY0 Intrinsic\7f313024
-Node: BesY1 Intrinsic\7f313486
-Node: BesYN Intrinsic\7f313948
-Node: Bit_Size Intrinsic\7f314483
-Node: BTest Intrinsic\7f315142
-Node: CAbs Intrinsic\7f315862
-Node: CCos Intrinsic\7f316249
-Node: Ceiling Intrinsic\7f316641
-Node: CExp Intrinsic\7f316963
-Node: Char Intrinsic\7f317355
-Node: ChDir Intrinsic (subroutine)\7f318609
-Node: ChMod Intrinsic (subroutine)\7f319613
-Node: CLog Intrinsic\7f320884
-Node: Cmplx Intrinsic\7f321288
-Node: Complex Intrinsic\7f322089
-Node: Conjg Intrinsic\7f323535
-Node: Cos Intrinsic\7f323959
-Node: CosH Intrinsic\7f324422
-Node: Count Intrinsic\7f324797
-Node: CPU_Time Intrinsic\7f325115
-Node: CShift Intrinsic\7f325906
-Node: CSin Intrinsic\7f326228
-Node: CSqRt Intrinsic\7f326620
-Node: CTime Intrinsic (subroutine)\7f327030
-Node: CTime Intrinsic (function)\7f327785
-Node: DAbs Intrinsic\7f328419
-Node: DACos Intrinsic\7f328815
-Node: DASin Intrinsic\7f329206
-Node: DATan Intrinsic\7f329598
-Node: DATan2 Intrinsic\7f329991
-Node: Date_and_Time Intrinsic\7f330446
-Node: DbesJ0 Intrinsic\7f331810
-Node: DbesJ1 Intrinsic\7f332203
-Node: DbesJN Intrinsic\7f332589
-Node: DbesY0 Intrinsic\7f333045
-Node: DbesY1 Intrinsic\7f333431
-Node: DbesYN Intrinsic\7f333817
-Node: Dble Intrinsic\7f334271
-Node: DCos Intrinsic\7f334977
-Node: DCosH Intrinsic\7f335361
-Node: DDiM Intrinsic\7f335751
-Node: DErF Intrinsic\7f336183
-Node: DErFC Intrinsic\7f336552
-Node: DExp Intrinsic\7f336927
-Node: Digits Intrinsic\7f337313
-Node: DiM Intrinsic\7f337630
-Node: DInt Intrinsic\7f338129
-Node: DLog Intrinsic\7f338513
-Node: DLog10 Intrinsic\7f338898
-Node: DMax1 Intrinsic\7f339296
-Node: DMin1 Intrinsic\7f339750
-Node: DMod Intrinsic\7f340202
-Node: DNInt Intrinsic\7f340630
-Node: Dot_Product Intrinsic\7f341029
-Node: DProd Intrinsic\7f341369
-Node: DSign Intrinsic\7f341751
-Node: DSin Intrinsic\7f342190
-Node: DSinH Intrinsic\7f342575
-Node: DSqRt Intrinsic\7f342966
-Node: DTan Intrinsic\7f343357
-Node: DTanH Intrinsic\7f343742
-Node: DTime Intrinsic (subroutine)\7f344146
-Node: EOShift Intrinsic\7f345417
-Node: Epsilon Intrinsic\7f345756
-Node: ErF Intrinsic\7f346080
-Node: ErFC Intrinsic\7f346486
-Node: ETime Intrinsic (subroutine)\7f347046
-Node: ETime Intrinsic (function)\7f348209
-Node: Exit Intrinsic\7f349249
-Node: Exp Intrinsic\7f349758
-Node: Exponent Intrinsic\7f350220
-Node: FDate Intrinsic (subroutine)\7f350559
-Node: FDate Intrinsic (function)\7f351469
-Node: FGet Intrinsic (subroutine)\7f352241
-Node: FGetC Intrinsic (subroutine)\7f353078
-Node: Float Intrinsic\7f353955
-Node: Floor Intrinsic\7f354355
-Node: Flush Intrinsic\7f354671
-Node: FNum Intrinsic\7f355250
-Node: FPut Intrinsic (subroutine)\7f355698
-Node: FPutC Intrinsic (subroutine)\7f356495
-Node: Fraction Intrinsic\7f357342
-Node: FSeek Intrinsic\7f357683
-Node: FStat Intrinsic (subroutine)\7f358408
-Node: FStat Intrinsic (function)\7f359933
-Node: FTell Intrinsic (subroutine)\7f361223
-Node: FTell Intrinsic (function)\7f361896
-Node: GError Intrinsic\7f362413
-Node: GetArg Intrinsic\7f362787
-Node: GetCWD Intrinsic (subroutine)\7f363455
-Node: GetCWD Intrinsic (function)\7f364311
-Node: GetEnv Intrinsic\7f364931
-Node: GetGId Intrinsic\7f365518
-Node: GetLog Intrinsic\7f365824
-Node: GetPId Intrinsic\7f366362
-Node: GetUId Intrinsic\7f366670
-Node: GMTime Intrinsic\7f366975
-Node: HostNm Intrinsic (subroutine)\7f367983
-Node: HostNm Intrinsic (function)\7f369073
-Node: Huge Intrinsic\7f369916
-Node: IAbs Intrinsic\7f370239
-Node: IAChar Intrinsic\7f370630
-Node: IAnd Intrinsic\7f371170
-Node: IArgC Intrinsic\7f371658
-Node: IBClr Intrinsic\7f372034
-Node: IBits Intrinsic\7f372545
-Node: IBSet Intrinsic\7f373259
-Node: IChar Intrinsic\7f373761
-Node: IDate Intrinsic (UNIX)\7f374980
-Node: IDiM Intrinsic\7f375783
-Node: IDInt Intrinsic\7f376232
-Node: IDNInt Intrinsic\7f376625
-Node: IEOr Intrinsic\7f377024
-Node: IErrNo Intrinsic\7f377522
-Node: IFix Intrinsic\7f377849
-Node: Imag Intrinsic\7f378237
-Node: ImagPart Intrinsic\7f379242
-Node: Index Intrinsic\7f380268
-Node: Int Intrinsic\7f380821
-Node: Int2 Intrinsic\7f381536
-Node: Int8 Intrinsic\7f382246
-Node: IOr Intrinsic\7f382956
-Node: IRand Intrinsic\7f383436
-Node: IsaTty Intrinsic\7f384356
-Node: IShft Intrinsic\7f384780
-Node: IShftC Intrinsic\7f385610
-Node: ISign Intrinsic\7f386539
-Node: ITime Intrinsic\7f386989
-Node: Kill Intrinsic (subroutine)\7f387391
-Node: Kind Intrinsic\7f388228
-Node: LBound Intrinsic\7f388553
-Node: Len Intrinsic\7f388870
-Node: Len_Trim Intrinsic\7f389506
-Node: LGe Intrinsic\7f389918
-Node: LGt Intrinsic\7f391331
-Node: Link Intrinsic (subroutine)\7f392236
-Node: LLe Intrinsic\7f393201
-Node: LLt Intrinsic\7f394106
-Node: LnBlnk Intrinsic\7f395000
-Node: Loc Intrinsic\7f395403
-Node: Log Intrinsic\7f395834
-Node: Log10 Intrinsic\7f396425
-Node: Logical Intrinsic\7f396967
-Node: Long Intrinsic\7f397290
-Node: LShift Intrinsic\7f397814
-Node: LStat Intrinsic (subroutine)\7f398850
-Node: LStat Intrinsic (function)\7f400662
-Node: LTime Intrinsic\7f402225
-Node: MatMul Intrinsic\7f403229
-Node: Max Intrinsic\7f403547
-Node: Max0 Intrinsic\7f404098
-Node: Max1 Intrinsic\7f404549
-Node: MaxExponent Intrinsic\7f405033
-Node: MaxLoc Intrinsic\7f405373
-Node: MaxVal Intrinsic\7f405700
-Node: MClock Intrinsic\7f406022
-Node: MClock8 Intrinsic\7f406920
-Node: Merge Intrinsic\7f408108
-Node: Min Intrinsic\7f408424
-Node: Min0 Intrinsic\7f408975
-Node: Min1 Intrinsic\7f409426
-Node: MinExponent Intrinsic\7f409910
-Node: MinLoc Intrinsic\7f410250
-Node: MinVal Intrinsic\7f410577
-Node: Mod Intrinsic\7f410896
-Node: Modulo Intrinsic\7f411419
-Node: MvBits Intrinsic\7f411738
-Node: Nearest Intrinsic\7f412604
-Node: NInt Intrinsic\7f412928
-Node: Not Intrinsic\7f413766
-Node: Or Intrinsic\7f414161
-Node: Pack Intrinsic\7f414659
-Node: PError Intrinsic\7f414969
-Node: Precision Intrinsic\7f415423
-Node: Present Intrinsic\7f415758
-Node: Product Intrinsic\7f416088
-Node: Radix Intrinsic\7f416414
-Node: Rand Intrinsic\7f416731
-Node: Random_Number Intrinsic\7f417618
-Node: Random_Seed Intrinsic\7f417971
-Node: Range Intrinsic\7f418319
-Node: Real Intrinsic\7f418640
-Node: RealPart Intrinsic\7f419646
-Node: Rename Intrinsic (subroutine)\7f420679
-Node: Repeat Intrinsic\7f421651
-Node: Reshape Intrinsic\7f421987
-Node: RRSpacing Intrinsic\7f422316
-Node: RShift Intrinsic\7f422651
-Node: Scale Intrinsic\7f423649
-Node: Scan Intrinsic\7f423965
-Node: Second Intrinsic (function)\7f424289
-Node: Second Intrinsic (subroutine)\7f425120
-Node: Selected_Int_Kind Intrinsic\7f426095
-Node: Selected_Real_Kind Intrinsic\7f426486
-Node: Set_Exponent Intrinsic\7f426873
-Node: Shape Intrinsic\7f427230
-Node: Short Intrinsic\7f427553
-Node: Sign Intrinsic\7f428249
-Node: Signal Intrinsic (subroutine)\7f428849
-Node: Sin Intrinsic\7f431063
-Node: SinH Intrinsic\7f431538
-Node: Sleep Intrinsic\7f431911
-Node: Sngl Intrinsic\7f432253
-Node: Spacing Intrinsic\7f432642
-Node: Spread Intrinsic\7f432966
-Node: SqRt Intrinsic\7f433287
-Node: SRand Intrinsic\7f433891
-Node: Stat Intrinsic (subroutine)\7f434268
-Node: Stat Intrinsic (function)\7f435883
-Node: Sum Intrinsic\7f437247
-Node: SymLnk Intrinsic (subroutine)\7f437579
-Node: System Intrinsic (subroutine)\7f438611
-Node: System_Clock Intrinsic\7f439550
-Node: Tan Intrinsic\7f440674
-Node: TanH Intrinsic\7f441134
-Node: Time Intrinsic (UNIX)\7f441516
-Node: Time8 Intrinsic\7f442501
-Node: Tiny Intrinsic\7f443680
-Node: Transfer Intrinsic\7f443995
-Node: Transpose Intrinsic\7f444326
-Node: Trim Intrinsic\7f444660
-Node: TtyNam Intrinsic (subroutine)\7f444990
-Node: TtyNam Intrinsic (function)\7f445692
-Node: UBound Intrinsic\7f446261
-Node: UMask Intrinsic (subroutine)\7f446606
-Node: Unlink Intrinsic (subroutine)\7f447303
-Node: Unpack Intrinsic\7f448201
-Node: Verify Intrinsic\7f448536
-Node: XOr Intrinsic\7f448855
-Node: ZAbs Intrinsic\7f449371
-Node: ZCos Intrinsic\7f449740
-Node: ZExp Intrinsic\7f450113
-Node: ZLog Intrinsic\7f450486
-Node: ZSin Intrinsic\7f450859
-Node: ZSqRt Intrinsic\7f451233
-Node: Scope and Classes of Names\7f451590
-Node: Underscores in Symbol Names\7f452072
-Node: I/O\7f452319
-Node: Fortran 90 Features\7f453092
-Node: Other Dialects\7f455894
-Node: Source Form\7f457053
-Node: Carriage Returns\7f458268
-Node: Tabs\7f458597
-Node: Short Lines\7f459470
-Node: Long Lines\7f460444
-Node: Ampersands\7f461055
-Node: Trailing Comment\7f461309
-Node: Debug Line\7f462085
-Node: Dollar Signs\7f462754
-Node: Case Sensitivity\7f463040
-Node: VXT Fortran\7f471656
-Node: Double Quote Meaning\7f472839
-Node: Exclamation Point\7f473767
-Node: Fortran 90\7f474810
-Node: Pedantic Compilation\7f475862
-Node: Distensions\7f479826
-Node: Ugly Implicit Argument Conversion\7f480790
-Node: Ugly Assumed-Size Arrays\7f481404
-Node: Ugly Complex Part Extraction\7f483125
-Node: Ugly Null Arguments\7f484747
-Node: Ugly Conversion of Initializers\7f486350
-Node: Ugly Integer Conversions\7f488115
-Node: Ugly Assigned Labels\7f489223
-Node: Compiler\7f491154
-Node: Compiler Limits\7f491792
-Node: Run-time Environment Limits\7f492683
-Node: Timer Wraparounds\7f494625
-Node: Year 2000 (Y2K) Problems\7f495904
-Node: Array Size\7f500410
-Node: Character-variable Length\7f501595
-Node: Year 10000 (Y10K) Problems\7f502104
-Node: Compiler Types\7f502650
-Node: Compiler Constants\7f507361
-Node: Compiler Intrinsics\7f508220
-Node: Intrinsic Groups\7f509147
-Node: Other Intrinsics\7f512588
-Node: ACosD Intrinsic\7f520186
-Node: AIMax0 Intrinsic\7f520467
-Node: AIMin0 Intrinsic\7f520776
-Node: AJMax0 Intrinsic\7f521086
-Node: AJMin0 Intrinsic\7f521396
-Node: ASinD Intrinsic\7f521705
-Node: ATan2D Intrinsic\7f522011
-Node: ATanD Intrinsic\7f522319
-Node: BITest Intrinsic\7f522625
-Node: BJTest Intrinsic\7f522934
-Node: CDAbs Intrinsic\7f523243
-Node: CDCos Intrinsic\7f523616
-Node: CDExp Intrinsic\7f523991
-Node: CDLog Intrinsic\7f524366
-Node: CDSin Intrinsic\7f524741
-Node: CDSqRt Intrinsic\7f525117
-Node: ChDir Intrinsic (function)\7f525510
-Node: ChMod Intrinsic (function)\7f526339
-Node: CosD Intrinsic\7f527453
-Node: DACosD Intrinsic\7f527765
-Node: DASinD Intrinsic\7f528073
-Node: DATan2D Intrinsic\7f528384
-Node: DATanD Intrinsic\7f528698
-Node: Date Intrinsic\7f529007
-Node: DbleQ Intrinsic\7f529726
-Node: DCmplx Intrinsic\7f530030
-Node: DConjg Intrinsic\7f531661
-Node: DCosD Intrinsic\7f532046
-Node: DFloat Intrinsic\7f532352
-Node: DFlotI Intrinsic\7f532724
-Node: DFlotJ Intrinsic\7f533034
-Node: DImag Intrinsic\7f533343
-Node: DReal Intrinsic\7f533720
-Node: DSinD Intrinsic\7f534867
-Node: DTanD Intrinsic\7f535171
-Node: DTime Intrinsic (function)\7f535486
-Node: FGet Intrinsic (function)\7f536716
-Node: FGetC Intrinsic (function)\7f537489
-Node: FloatI Intrinsic\7f538305
-Node: FloatJ Intrinsic\7f538625
-Node: FPut Intrinsic (function)\7f538944
-Node: FPutC Intrinsic (function)\7f539680
-Node: IDate Intrinsic (VXT)\7f540473
-Node: IIAbs Intrinsic\7f541517
-Node: IIAnd Intrinsic\7f541827
-Node: IIBClr Intrinsic\7f542132
-Node: IIBits Intrinsic\7f542441
-Node: IIBSet Intrinsic\7f542751
-Node: IIDiM Intrinsic\7f543060
-Node: IIDInt Intrinsic\7f543366
-Node: IIDNnt Intrinsic\7f543675
-Node: IIEOr Intrinsic\7f543984
-Node: IIFix Intrinsic\7f544289
-Node: IInt Intrinsic\7f544592
-Node: IIOr Intrinsic\7f544891
-Node: IIQint Intrinsic\7f545191
-Node: IIQNnt Intrinsic\7f545499
-Node: IIShftC Intrinsic\7f545810
-Node: IISign Intrinsic\7f546124
-Node: IMax0 Intrinsic\7f546434
-Node: IMax1 Intrinsic\7f546739
-Node: IMin0 Intrinsic\7f547043
-Node: IMin1 Intrinsic\7f547347
-Node: IMod Intrinsic\7f547650
-Node: INInt Intrinsic\7f547950
-Node: INot Intrinsic\7f548252
-Node: IZExt Intrinsic\7f548552
-Node: JIAbs Intrinsic\7f548855
-Node: JIAnd Intrinsic\7f549159
-Node: JIBClr Intrinsic\7f549464
-Node: JIBits Intrinsic\7f549773
-Node: JIBSet Intrinsic\7f550083
-Node: JIDiM Intrinsic\7f550392
-Node: JIDInt Intrinsic\7f550698
-Node: JIDNnt Intrinsic\7f551007
-Node: JIEOr Intrinsic\7f551316
-Node: JIFix Intrinsic\7f551621
-Node: JInt Intrinsic\7f551924
-Node: JIOr Intrinsic\7f552223
-Node: JIQint Intrinsic\7f552523
-Node: JIQNnt Intrinsic\7f552831
-Node: JIShft Intrinsic\7f553141
-Node: JIShftC Intrinsic\7f553452
-Node: JISign Intrinsic\7f553766
-Node: JMax0 Intrinsic\7f554076
-Node: JMax1 Intrinsic\7f554381
-Node: JMin0 Intrinsic\7f554685
-Node: JMin1 Intrinsic\7f554989
-Node: JMod Intrinsic\7f555292
-Node: JNInt Intrinsic\7f555592
-Node: JNot Intrinsic\7f555894
-Node: JZExt Intrinsic\7f556194
-Node: Kill Intrinsic (function)\7f556507
-Node: Link Intrinsic (function)\7f557189
-Node: QAbs Intrinsic\7f558001
-Node: QACos Intrinsic\7f558311
-Node: QACosD Intrinsic\7f558615
-Node: QASin Intrinsic\7f558923
-Node: QASinD Intrinsic\7f559229
-Node: QATan Intrinsic\7f559537
-Node: QATan2 Intrinsic\7f559843
-Node: QATan2D Intrinsic\7f560153
-Node: QATanD Intrinsic\7f560467
-Node: QCos Intrinsic\7f560776
-Node: QCosD Intrinsic\7f561077
-Node: QCosH Intrinsic\7f561380
-Node: QDiM Intrinsic\7f561683
-Node: QExp Intrinsic\7f561982
-Node: QExt Intrinsic\7f562280
-Node: QExtD Intrinsic\7f562579
-Node: QFloat Intrinsic\7f562883
-Node: QInt Intrinsic\7f563190
-Node: QLog Intrinsic\7f563490
-Node: QLog10 Intrinsic\7f563790
-Node: QMax1 Intrinsic\7f564097
-Node: QMin1 Intrinsic\7f564402
-Node: QMod Intrinsic\7f564705
-Node: QNInt Intrinsic\7f565005
-Node: QSin Intrinsic\7f565307
-Node: QSinD Intrinsic\7f565607
-Node: QSinH Intrinsic\7f565910
-Node: QSqRt Intrinsic\7f566214
-Node: QTan Intrinsic\7f566517
-Node: QTanD Intrinsic\7f566817
-Node: QTanH Intrinsic\7f567120
-Node: Rename Intrinsic (function)\7f567436
-Node: Secnds Intrinsic\7f568241
-Node: Signal Intrinsic (function)\7f568840
-Node: SinD Intrinsic\7f571669
-Node: SnglQ Intrinsic\7f571981
-Node: SymLnk Intrinsic (function)\7f572296
-Node: System Intrinsic (function)\7f573164
-Node: TanD Intrinsic\7f574491
-Node: Time Intrinsic (VXT)\7f574808
-Node: UMask Intrinsic (function)\7f575562
-Node: Unlink Intrinsic (function)\7f576170
-Node: ZExt Intrinsic\7f576899
-Node: Other Compilers\7f577187
-Node: Dropping f2c Compatibility\7f579707
-Node: Compilers Other Than f2c\7f582779
-Node: Other Languages\7f584577
-Node: Interoperating with C and C++\7f584842
-Node: C Interfacing Tools\7f585875
-Node: C Access to Type Information\7f586803
-Node: f2c Skeletons and Prototypes\7f587490
-Ref: f2c Skeletons and Prototypes-Footnote-1\7f588937
-Node: C++ Considerations\7f589191
-Node: Startup Code\7f589846
-Node: Debugging and Interfacing\7f594635
-Node: Main Program Unit\7f597322
-Node: Procedures\7f599816
-Node: Functions\7f602474
-Node: Names\7f604092
-Node: Common Blocks\7f607235
-Node: Local Equivalence Areas\7f607499
-Node: Complex Variables\7f608483
-Node: Arrays\7f609603
-Node: Adjustable Arrays\7f612937
-Node: Alternate Entry Points\7f615796
-Node: Alternate Returns\7f622498
-Node: Assigned Statement Labels\7f623399
-Node: Run-time Library Errors\7f625244
-Node: Collected Fortran Wisdom\7f627196
-Node: Advantages Over f2c\7f628632
-Node: Language Extensions\7f629613
-Node: Diagnostic Abilities\7f630787
-Node: Compiler Options\7f631178
-Node: Compiler Speed\7f632226
-Node: Program Speed\7f632936
-Node: Ease of Debugging\7f634521
-Node: Character and Hollerith Constants\7f636951
-Node: Block Data and Libraries\7f637923
-Node: Loops\7f641252
-Node: Working Programs\7f646478
-Node: Not My Type\7f647222
-Node: Variables Assumed To Be Zero\7f649153
-Node: Variables Assumed To Be Saved\7f650207
-Node: Unwanted Variables\7f651577
-Node: Unused Arguments\7f652457
-Node: Surprising Interpretations of Code\7f652920
-Node: Aliasing Assumed To Work\7f653767
-Node: Output Assumed To Flush\7f659964
-Node: Large File Unit Numbers\7f662737
-Node: Floating-point precision\7f664889
-Node: Inconsistent Calling Sequences\7f666150
-Node: Overly Convenient Options\7f667130
-Node: Faster Programs\7f670436
-Node: Aligned Data\7f670882
-Node: Prefer Automatic Uninitialized Variables\7f675759
-Node: Avoid f2c Compatibility\7f677125
-Node: Use Submodel Options\7f677593
-Node: Trouble\7f678597
-Node: But-bugs\7f680059
-Node: Signal 11 and Friends\7f681832
-Node: Cannot Link Fortran Programs\7f683912
-Node: Large Common Blocks\7f685195
-Node: Debugger Problems\7f685621
-Node: NeXTStep Problems\7f686336
-Node: Stack Overflow\7f688162
-Node: Nothing Happens\7f691051
-Node: Strange Behavior at Run Time\7f692665
-Node: Floating-point Errors\7f695154
-Node: Known Bugs\7f701448
-Node: Missing Features\7f708751
-Node: Better Source Model\7f710678
-Node: Fortran 90 Support\7f712447
-Node: Intrinsics in PARAMETER Statements\7f713548
-Node: Arbitrary Concatenation\7f714299
-Node: SELECT CASE on CHARACTER Type\7f714702
-Node: RECURSIVE Keyword\7f714989
-Node: Increasing Precision/Range\7f715416
-Node: Popular Non-standard Types\7f716954
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+++ /dev/null
-This is gcj.info, produced by makeinfo version 4.5 from gcj.texi.
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-INFO-DIR-SECTION Programming
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-* Gcj: (gcj). Ahead-of-time compiler for the Java language
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-INFO-DIR-SECTION Individual utilities
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-* gcjh: (gcj)Invoking gcjh.
- Generate header files from Java class files
-* jv-scan: (gcj)Invoking jv-scan.
- Print information about Java source files
-* jcf-dump: (gcj)Invoking jcf-dump.
- Print information about Java class files
-* gij: (gcj)Invoking gij. GNU interpreter for Java bytecode
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- Convert file from one encoding to another
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- Generate stubs for Remote Method Invocation.
-* rmiregistry: (gcj)Invoking rmiregistry.
- The remote object registry.
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- Copyright (C) 2001, 2002 Free Software Foundation, Inc.
-
- Permission is granted to copy, distribute and/or modify this document
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-Invariant Sections being "GNU General Public License", the Front-Cover
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-(see below). A copy of the license is included in the section entitled
-"GNU Free Documentation License".
-
- (a) The FSF's Front-Cover Text is:
-
- A GNU Manual
-
- (b) The FSF's Back-Cover Text is:
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- You have freedom to copy and modify this GNU Manual, like GNU
-software. Copies published by the Free Software Foundation raise
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projects / msp430-gcc.git / commitdiff