+++ /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.
-
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