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-.\" ======================================================================
-.\"
-.IX Title "G77 1"
-.TH G77 1 "gcc-3.2.3" "2003-04-22" "GNU"
-.UC
-.SH "NAME"
-g77 \- \s-1GNU\s0 project Fortran 77 compiler
-.SH "SYNOPSIS"
-.IX Header "SYNOPSIS"
-g77 [\fB\-c\fR|\fB\-S\fR|\fB\-E\fR]
- [\fB\-g\fR] [\fB\-pg\fR] [\fB\-O\fR\fIlevel\fR]
- [\fB\-W\fR\fIwarn\fR...] [\fB\-pedantic\fR]
- [\fB\-I\fR\fIdir\fR...] [\fB\-L\fR\fIdir\fR...]
- [\fB\-D\fR\fImacro\fR[=\fIdefn\fR]...] [\fB\-U\fR\fImacro\fR]
- [\fB\-f\fR\fIoption\fR...] [\fB\-m\fR\fImachine-option\fR...]
- [\fB\-o\fR \fIoutfile\fR] \fIinfile\fR...
-.PP
-Only the most useful options are listed here; see below for the
-remainder.
-.SH "DESCRIPTION"
-.IX Header "DESCRIPTION"
-The \fBg77\fR command supports all the options supported by the
-\&\fBgcc\fR command.
-.PP
-All \fBgcc\fR and \fBg77\fR options
-are accepted both by \fBg77\fR and by \fBgcc\fR
-(as well as any other drivers built at the same time,
-such as \fBg++\fR),
-since adding \fBg77\fR to the \fBgcc\fR distribution
-enables acceptance of \fBg77\fR options
-by all of the relevant drivers.
-.PP
-In some cases, options have positive and negative forms;
-the negative form of \fB\-ffoo\fR would be \fB\-fno-foo\fR.
-This manual documents only one of these two forms, whichever
-one is not the default.
-.SH "OPTIONS"
-.IX Header "OPTIONS"
-Here is a summary of all the options specific to \s-1GNU\s0 Fortran, grouped
-by type. Explanations are in the following sections.
-.Ip "\fIOverall Options\fR" 4
-.IX Item "Overall Options"
-\&\fB\-fversion \-fset-g77\-defaults \-fno-silent\fR
-.Ip "\fIShorthand Options\fR" 4
-.IX Item "Shorthand Options"
-\&\fB\-ff66 \-fno-f66 \-ff77 \-fno-f77 \-fno-ugly\fR
-.Ip "\fIFortran Language Options\fR" 4
-.IX Item "Fortran Language Options"
-\&\fB\-ffree-form \-fno-fixed-form \-ff90
-\&\-fvxt \-fdollar-ok \-fno-backslash
-\&\-fno-ugly-args \-fno-ugly-assign \-fno-ugly-assumed
-\&\-fugly-comma \-fugly-complex \-fugly-init \-fugly-logint
-\&\-fonetrip \-ftypeless-boz
-\&\-fintrin-case-initcap \-fintrin-case-upper
-\&\-fintrin-case-lower \-fintrin-case-any
-\&\-fmatch-case-initcap \-fmatch-case-upper
-\&\-fmatch-case-lower \-fmatch-case-any
-\&\-fsource-case-upper \-fsource-case-lower
-\&\-fsource-case-preserve
-\&\-fsymbol-case-initcap \-fsymbol-case-upper
-\&\-fsymbol-case-lower \-fsymbol-case-any
-\&\-fcase-strict-upper \-fcase-strict-lower
-\&\-fcase-initcap \-fcase-upper \-fcase-lower \-fcase-preserve
-\&\-ff2c-intrinsics-delete \-ff2c-intrinsics-hide
-\&\-ff2c-intrinsics-disable \-ff2c-intrinsics-enable
-\&\-fbadu77\-intrinsics-delete \-fbadu77\-intrinsics-hide
-\&\-fbadu77\-intrinsics-disable \-fbadu77\-intrinsics-enable
-\&\-ff90\-intrinsics-delete \-ff90\-intrinsics-hide
-\&\-ff90\-intrinsics-disable \-ff90\-intrinsics-enable
-\&\-fgnu-intrinsics-delete \-fgnu-intrinsics-hide
-\&\-fgnu-intrinsics-disable \-fgnu-intrinsics-enable
-\&\-fmil-intrinsics-delete \-fmil-intrinsics-hide
-\&\-fmil-intrinsics-disable \-fmil-intrinsics-enable
-\&\-funix-intrinsics-delete \-funix-intrinsics-hide
-\&\-funix-intrinsics-disable \-funix-intrinsics-enable
-\&\-fvxt-intrinsics-delete \-fvxt-intrinsics-hide
-\&\-fvxt-intrinsics-disable \-fvxt-intrinsics-enable
-\&\-ffixed-line-length-\fR\fIn\fR \fB\-ffixed-line-length-none\fR
-.Ip "\fIWarning Options\fR" 4
-.IX Item "Warning Options"
-\&\fB\-fsyntax-only \-pedantic \-pedantic-errors \-fpedantic
-\&\-w \-Wno-globals \-Wimplicit \-Wunused \-Wuninitialized
-\&\-Wall \-Wsurprising
-\&\-Werror \-W\fR
-.Ip "\fIDebugging Options\fR" 4
-.IX Item "Debugging Options"
-\&\fB\-g\fR
-.Ip "\fIOptimization Options\fR" 4
-.IX Item "Optimization Options"
-\&\fB\-malign-double
-\&\-ffloat-store \-fforce-mem \-fforce-addr \-fno-inline
-\&\-ffast-math \-fstrength-reduce \-frerun-cse-after-loop
-\&\-funsafe-math-optimizations \-fno-trapping-math
-\&\-fexpensive-optimizations \-fdelayed-branch
-\&\-fschedule-insns \-fschedule-insn2 \-fcaller-saves
-\&\-funroll-loops \-funroll-all-loops
-\&\-fno-move-all-movables \-fno-reduce-all-givs
-\&\-fno-rerun-loop-opt\fR
-.Ip "\fIDirectory Options\fR" 4
-.IX Item "Directory Options"
-\&\fB\-I\fR\fIdir\fR \fB\-I-\fR
-.Ip "\fICode Generation Options\fR" 4
-.IX Item "Code Generation Options"
-\&\fB\-fno-automatic \-finit-local-zero \-fno-f2c
-\&\-ff2c-library \-fno-underscoring \-fno-ident
-\&\-fpcc-struct-return \-freg-struct-return
-\&\-fshort-double \-fno-common \-fpack-struct
-\&\-fzeros \-fno-second-underscore
-\&\-femulate-complex
-\&\-falias-check \-fargument-alias
-\&\-fargument-noalias \-fno-argument-noalias-global
-\&\-fno-globals \-fflatten-arrays
-\&\-fbounds-check \-ffortran-bounds-check\fR
-.PP
-Compilation can involve as many as four stages: preprocessing, code
-generation (often what is really meant by the term ``compilation''),
-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
-compiled, and those specified as input) into an executable file.
-.PP
-For any given input file, the file name suffix determines what kind of
-program is contained in the file\-\-\-that is, the language in which the
-program is written is generally indicated by the suffix.
-Suffixes specific to \s-1GNU\s0 Fortran are listed below.
-.Ip "\fIfile\fR\fB.f\fR" 4
-.IX Item "file.f"
-.PD 0
-.Ip "\fIfile\fR\fB.for\fR" 4
-.IX Item "file.for"
-.Ip "\fIfile\fR\fB.FOR\fR" 4
-.IX Item "file.FOR"
-.PD
-Fortran source code that should not be preprocessed.
-.Sp
-Such source code cannot contain any preprocessor directives, such
-as \f(CW\*(C`#include\*(C'\fR, \f(CW\*(C`#define\*(C'\fR, \f(CW\*(C`#if\*(C'\fR, and so on.
-.Sp
-You can force \fB.f\fR files to be preprocessed by \fBcpp\fR by using
-\&\fB\-x f77\-cpp-input\fR.
-.Ip "\fIfile\fR\fB.F\fR" 4
-.IX Item "file.F"
-.PD 0
-.Ip "\fIfile\fR\fB.fpp\fR" 4
-.IX Item "file.fpp"
-.Ip "\fIfile\fR\fB.FPP\fR" 4
-.IX Item "file.FPP"
-.PD
-Fortran source code that must be preprocessed (by the C preprocessor
-\&\fBcpp\fR, which is part of \s-1GNU\s0 \s-1CC\s0).
-.Sp
-Note that preprocessing is not extended to the contents of
-files included by the \f(CW\*(C`INCLUDE\*(C'\fR directive\-\-\-the \f(CW\*(C`#include\*(C'\fR
-preprocessor directive must be used instead.
-.Ip "\fIfile\fR\fB.r\fR" 4
-.IX Item "file.r"
-Ratfor source code, which must be preprocessed by the \fBratfor\fR
-command, which is available separately (as it is not yet part of the \s-1GNU\s0
-Fortran distribution).
-One version in Fortran, adapted for use with \fBg77\fR is at
-<\fBftp://members.aol.com/n8tm/rat7.uue\fR> (of uncertain copyright
-status). Another, public domain version in C is at
-<\fBhttp://sepwww.stanford.edu/sep/prof/ratfor.shar.2\fR>.
-.PP
-\&\s-1UNIX\s0 users typically use the \fI\fIfile\fI.f\fR and \fI\fIfile\fI.F\fR
-nomenclature.
-Users of other operating systems, especially those that cannot
-distinguish upper-case
-letters from lower-case letters in their file names, typically use
-the \fI\fIfile\fI.for\fR and \fI\fIfile\fI.fpp\fR nomenclature.
-.PP
-Use of the preprocessor \fBcpp\fR allows use of C-like
-constructs such as \f(CW\*(C`#define\*(C'\fR and \f(CW\*(C`#include\*(C'\fR, but can
-lead to unexpected, even mistaken, results due to Fortran's source file
-format.
-It is recommended that use of the C preprocessor
-be limited to \f(CW\*(C`#include\*(C'\fR and, in
-conjunction with \f(CW\*(C`#define\*(C'\fR, only \f(CW\*(C`#if\*(C'\fR and related directives,
-thus avoiding in-line macro expansion entirely.
-This recommendation applies especially
-when using the traditional fixed source form.
-With free source form,
-fewer unexpected transformations are likely to happen, but use of
-constructs such as Hollerith and character constants can nevertheless
-present problems, especially when these are continued across multiple
-source lines.
-These problems result, primarily, from differences between the way
-such constants are interpreted by the C preprocessor and by a Fortran
-compiler.
-.PP
-Another example of a problem that results from using the C preprocessor
-is that a Fortran comment line that happens to contain any
-characters ``interesting'' to the C preprocessor,
-such as a backslash at the end of the line,
-is not recognized by the preprocessor as a comment line,
-so instead of being passed through ``raw'',
-the line is edited according to the rules for the preprocessor.
-For example, the backslash at the end of the line is removed,
-along with the subsequent newline, resulting in the next
-line being effectively commented out\-\-\-unfortunate if that
-line is a non-comment line of important code!
-.PP
-\&\fINote:\fR The \fB\-traditional\fR and \fB\-undef\fR flags are supplied
-to \fBcpp\fR by default, to help avoid unpleasant surprises.
-.PP
-This means that \s-1ANSI\s0 C preprocessor features (such as the \fB#\fR
-operator) aren't available, and only variables in the C reserved
-namespace (generally, names with a leading underscore) are liable to
-substitution by C predefines.
-Thus, if you want to do system-specific
-tests, use, for example, \fB#ifdef _\|_linux_\|_\fR rather than \fB#ifdef linux\fR.
-Use the \fB\-v\fR option to see exactly how the preprocessor is invoked.
-.PP
-Unfortunately, the \fB\-traditional\fR flag will not avoid an error from
-anything that \fBcpp\fR sees as an unterminated C comment, such as:
-.PP
-.Vb 2
-\& C Some Fortran compilers accept /* as starting
-\& C an inline comment.
-.Ve
-The following options that affect overall processing are recognized
-by the \fBg77\fR and \fBgcc\fR commands in a \s-1GNU\s0 Fortran installation:
-.Ip "\fB\-fversion\fR" 4
-.IX Item "-fversion"
-Ensure that the \fBg77\fR version of the compiler phase is reported,
-if run,
-and, starting in \f(CW\*(C`egcs\*(C'\fR version 1.1,
-that internal consistency checks in the \fIf771\fR program are run.
-.Sp
-This option is supplied automatically when \fB\-v\fR or \fB\*(--verbose\fR
-is specified as a command-line option for \fBg77\fR or \fBgcc\fR
-and when the resulting commands compile Fortran source files.
-.Sp
-In \s-1GCC\s0 3.1, this is changed back to the behaviour \fBgcc\fR displays
-for \fB.c\fR files.
-.Ip "\fB\-fset-g77\-defaults\fR" 4
-.IX Item "-fset-g77-defaults"
-\&\fIVersion info:\fR
-This option was obsolete as of \f(CW\*(C`egcs\*(C'\fR
-version 1.1.
-The effect is instead achieved
-by the \f(CW\*(C`lang_init_options\*(C'\fR routine
-in \fIgcc/gcc/f/com.c\fR.
-.Sp
-Set up whatever \fBgcc\fR options are to apply to Fortran
-compilations, and avoid running internal consistency checks
-that might take some time.
-.Sp
-This option is supplied automatically when compiling Fortran code
-via the \fBg77\fR or \fBgcc\fR command.
-The description of this option is provided so that users seeing
-it in the output of, say, \fBg77 \-v\fR understand why it is
-there.
-.Sp
-Also, developers who run \f(CW\*(C`f771\*(C'\fR directly might want to specify it
-by hand to get the same defaults as they would running \f(CW\*(C`f771\*(C'\fR
-via \fBg77\fR or \fBgcc\fR
-However, such developers should, after linking a new \f(CW\*(C`f771\*(C'\fR
-executable, invoke it without this option once,
-e.g. via \f(CW\*(C`./f771 \-quiet < /dev/null\*(C'\fR,
-to ensure that they have not introduced any
-internal inconsistencies (such as in the table of
-intrinsics) before proceeding\-\--\fBg77\fR will crash
-with a diagnostic if it detects an inconsistency.
-.Ip "\fB\-fno-silent\fR" 4
-.IX Item "-fno-silent"
-Print (to \f(CW\*(C`stderr\*(C'\fR) the names of the program units as
-they are compiled, in a form similar to that used by popular
-\&\s-1UNIX\s0 \fBf77\fR implementations and \fBf2c\fR
-.Sh "Shorthand Options"
-.IX Subsection "Shorthand Options"
-The following options serve as ``shorthand''
-for other options accepted by the compiler:
-.Ip "\fB\-fugly\fR" 4
-.IX Item "-fugly"
-\&\fINote:\fR This option is no longer supported.
-The information, below, is provided to aid
-in the conversion of old scripts.
-.Sp
-Specify that certain ``ugly'' constructs are to be quietly accepted.
-Same as:
-.Sp
-.Vb 3
-\& -fugly-args -fugly-assign -fugly-assumed
-\& -fugly-comma -fugly-complex -fugly-init
-\& -fugly-logint
-.Ve
-These constructs are considered inappropriate to use in new
-or well-maintained portable Fortran code, but widely used
-in old code.
-.Ip "\fB\-fno-ugly\fR" 4
-.IX Item "-fno-ugly"
-Specify that all ``ugly'' constructs are to be noisily rejected.
-Same as:
-.Sp
-.Vb 3
-\& -fno-ugly-args -fno-ugly-assign -fno-ugly-assumed
-\& -fno-ugly-comma -fno-ugly-complex -fno-ugly-init
-\& -fno-ugly-logint
-.Ve
-.Ip "\fB\-ff66\fR" 4
-.IX Item "-ff66"
-Specify that the program is written in idiomatic \s-1FORTRAN\s0 66.
-Same as \fB\-fonetrip \-fugly-assumed\fR.
-.Sp
-The \fB\-fno-f66\fR option is the inverse of \fB\-ff66\fR.
-As such, it is the same as \fB\-fno-onetrip \-fno-ugly-assumed\fR.
-.Sp
-The meaning of this option is likely to be refined as future
-versions of \fBg77\fR provide more compatibility with other
-existing and obsolete Fortran implementations.
-.Ip "\fB\-ff77\fR" 4
-.IX Item "-ff77"
-Specify that the program is written in idiomatic \s-1UNIX\s0 \s-1FORTRAN\s0 77
-and/or the dialect accepted by the \fBf2c\fR product.
-Same as \fB\-fbackslash \-fno-typeless-boz\fR.
-.Sp
-The meaning of this option is likely to be refined as future
-versions of \fBg77\fR provide more compatibility with other
-existing and obsolete Fortran implementations.
-.Ip "\fB\-fno-f77\fR" 4
-.IX Item "-fno-f77"
-The \fB\-fno-f77\fR option is \fInot\fR the inverse
-of \fB\-ff77\fR.
-It specifies that the program is not written in idiomatic \s-1UNIX\s0
-\&\s-1FORTRAN\s0 77 or \fBf2c\fR but in a more widely portable dialect.
-\&\fB\-fno-f77\fR is the same as \fB\-fno-backslash\fR.
-.Sp
-The meaning of this option is likely to be refined as future
-versions of \fBg77\fR provide more compatibility with other
-existing and obsolete Fortran implementations.
-.Sh "Options Controlling Fortran Dialect"
-.IX Subsection "Options Controlling Fortran Dialect"
-The following options control the dialect of Fortran
-that the compiler accepts:
-.Ip "\fB\-ffree-form\fR" 4
-.IX Item "-ffree-form"
-.PD 0
-.Ip "\fB\-fno-fixed-form\fR" 4
-.IX Item "-fno-fixed-form"
-.PD
-Specify that the source file is written in free form
-(introduced in Fortran 90) instead of the more-traditional fixed form.
-.Ip "\fB\-ff90\fR" 4
-.IX Item "-ff90"
-Allow certain Fortran-90 constructs.
-.Sp
-This option controls whether certain
-Fortran 90 constructs are recognized.
-(Other Fortran 90 constructs
-might or might not be recognized depending on other options such as
-\&\fB\-fvxt\fR, \fB\-ff90\-intrinsics-enable\fR, and the
-current level of support for Fortran 90.)
-.Ip "\fB\-fvxt\fR" 4
-.IX Item "-fvxt"
-Specify the treatment of certain constructs that have different
-meanings depending on whether the code is written in
-\&\s-1GNU\s0 Fortran (based on \s-1FORTRAN\s0 77 and akin to Fortran 90)
-or \s-1VXT\s0 Fortran (more like \s-1VAX\s0 \s-1FORTRAN\s0).
-.Sp
-The default is \fB\-fno-vxt\fR.
-\&\fB\-fvxt\fR specifies that the \s-1VXT\s0 Fortran interpretations
-for those constructs are to be chosen.
-.Ip "\fB\-fdollar-ok\fR" 4
-.IX Item "-fdollar-ok"
-Allow \fB$\fR as a valid character in a symbol name.
-.Ip "\fB\-fno-backslash\fR" 4
-.IX Item "-fno-backslash"
-Specify that \fB\e\fR is not to be specially interpreted in character
-and Hollerith constants a la C and many \s-1UNIX\s0 Fortran compilers.
-.Sp
-For example, with \fB\-fbackslash\fR in effect, \fBA\enB\fR specifies
-three characters, with the second one being newline.
-With \fB\-fno-backslash\fR, it specifies four characters,
-\&\fBA\fR, \fB\e\fR, \fBn\fR, and \fBB\fR.
-.Sp
-Note that \fBg77\fR implements a fairly general form of backslash
-processing that is incompatible with the narrower forms supported
-by some other compilers.
-For example, \fB'A\e003B'\fR is a three-character string in \fBg77\fR
-whereas other compilers that support backslash might not support
-the three-octal-digit form, and thus treat that string as longer
-than three characters.
-.Ip "\fB\-fno-ugly-args\fR" 4
-.IX Item "-fno-ugly-args"
-Disallow passing Hollerith and typeless constants as actual
-arguments (for example, \fB\s-1CALL\s0 FOO(4HABCD)\fR).
-.Ip "\fB\-fugly-assign\fR" 4
-.IX Item "-fugly-assign"
-Use the same storage for a given variable regardless of
-whether it is used to hold an assigned-statement label
-(as in \fB\s-1ASSIGN\s0 10 \s-1TO\s0 I\fR) or used to hold numeric data
-(as in \fBI = 3\fR).
-.Ip "\fB\-fugly-assumed\fR" 4
-.IX Item "-fugly-assumed"
-Assume any dummy array with a final dimension specified as \fB1\fR
-is really an assumed-size array, as if \fB*\fR had been specified
-for the final dimension instead of \fB1\fR.
-.Sp
-For example, \fB\s-1DIMENSION\s0 X(1)\fR is treated as if it
-had read \fB\s-1DIMENSION\s0 X(*)\fR.
-.Ip "\fB\-fugly-comma\fR" 4
-.IX Item "-fugly-comma"
-In an external-procedure invocation,
-treat a trailing comma in the argument list
-as specification of a trailing null argument,
-and treat an empty argument list
-as specification of a single null argument.
-.Sp
-For example, \fB\s-1CALL\s0 \f(BIFOO\fB\|(,)\fR is treated as
-\&\fB\s-1CALL\s0 FOO(%\f(BIVAL\fB\|(0), %\f(BIVAL\fB\|(0))\fR.
-That is, \fItwo\fR null arguments are specified
-by the procedure call when \fB\-fugly-comma\fR is in force.
-And \fBF = \f(BIFUNC()\fB\fR is treated as \fBF = FUNC(%\f(BIVAL\fB\|(0))\fR.
-.Sp
-The default behavior, \fB\-fno-ugly-comma\fR, is to ignore
-a single trailing comma in an argument list.
-So, by default, \fB\s-1CALL\s0 FOO(X,)\fR is treated
-exactly the same as \fB\s-1CALL\s0 \f(BIFOO\fB\|(X)\fR.
-.Ip "\fB\-fugly-complex\fR" 4
-.IX Item "-fugly-complex"
-Do not complain about \fBREAL(\fR\fIexpr\fR\fB)\fR or
-\&\fBAIMAG(\fR\fIexpr\fR\fB)\fR when \fIexpr\fR is a \f(CW\*(C`COMPLEX\*(C'\fR
-type other than \f(CW\*(C`COMPLEX(KIND=1)\*(C'\fR\-\-\-usually
-this is used to permit \f(CW\*(C`COMPLEX(KIND=2)\*(C'\fR
-(\f(CW\*(C`DOUBLE COMPLEX\*(C'\fR) operands.
-.Sp
-The \fB\-ff90\fR option controls the interpretation
-of this construct.
-.Ip "\fB\-fno-ugly-init\fR" 4
-.IX Item "-fno-ugly-init"
-Disallow use of Hollerith and typeless constants as initial
-values (in \f(CW\*(C`PARAMETER\*(C'\fR and \f(CW\*(C`DATA\*(C'\fR statements), and
-use of character constants to
-initialize numeric types and vice versa.
-.Sp
-For example, \fB\s-1DATA\s0 I/'F'/, \s-1CHRVAR/65/\s0, J/4HABCD/\fR is disallowed by
-\&\fB\-fno-ugly-init\fR.
-.Ip "\fB\-fugly-logint\fR" 4
-.IX Item "-fugly-logint"
-Treat \f(CW\*(C`INTEGER\*(C'\fR and \f(CW\*(C`LOGICAL\*(C'\fR variables and
-expressions as potential stand-ins for each other.
-.Sp
-For example, automatic conversion between \f(CW\*(C`INTEGER\*(C'\fR and
-\&\f(CW\*(C`LOGICAL\*(C'\fR is enabled, for many contexts, via this option.
-.Ip "\fB\-fonetrip\fR" 4
-.IX Item "-fonetrip"
-Executable iterative \f(CW\*(C`DO\*(C'\fR loops are to be executed at
-least once each time they are reached.
-.Sp
-\&\s-1ANSI\s0 \s-1FORTRAN\s0 77 and more recent versions of the Fortran standard
-specify that the body of an iterative \f(CW\*(C`DO\*(C'\fR loop is not executed
-if the number of iterations calculated from the parameters of the
-loop is less than 1.
-(For example, \fB\s-1DO\s0 10 I = 1, 0\fR.)
-Such a loop is called a \fIzero-trip loop\fR.
-.Sp
-Prior to \s-1ANSI\s0 \s-1FORTRAN\s0 77, many compilers implemented \f(CW\*(C`DO\*(C'\fR loops
-such that the body of a loop would be executed at least once, even
-if the iteration count was zero.
-Fortran code written assuming this behavior is said to require
-\&\fIone-trip loops\fR.
-For example, some code written to the \s-1FORTRAN\s0 66 standard
-expects this behavior from its \f(CW\*(C`DO\*(C'\fR loops, although that
-standard did not specify this behavior.
-.Sp
-The \fB\-fonetrip\fR option specifies that the source \fIfile\fR\|(s) being
-compiled require one-trip loops.
-.Sp
-This option affects only those loops specified by the (iterative) \f(CW\*(C`DO\*(C'\fR
-statement and by implied-\f(CW\*(C`DO\*(C'\fR lists in I/O statements.
-Loops specified by implied-\f(CW\*(C`DO\*(C'\fR lists in \f(CW\*(C`DATA\*(C'\fR and
-specification (non-executable) statements are not affected.
-.Ip "\fB\-ftypeless-boz\fR" 4
-.IX Item "-ftypeless-boz"
-Specifies that prefix-radix non-decimal constants, such as
-\&\fBZ'\s-1ABCD\s0'\fR, are typeless instead of \f(CW\*(C`INTEGER(KIND=1)\*(C'\fR.
-.Sp
-You can test for yourself whether a particular compiler treats
-the prefix form as \f(CW\*(C`INTEGER(KIND=1)\*(C'\fR or typeless by running the
-following program:
-.Sp
-.Vb 6
-\& EQUIVALENCE (I, R)
-\& R = Z'ABCD1234'
-\& J = Z'ABCD1234'
-\& IF (J .EQ. I) PRINT *, 'Prefix form is TYPELESS'
-\& IF (J .NE. I) PRINT *, 'Prefix form is INTEGER'
-\& END
-.Ve
-Reports indicate that many compilers process this form as
-\&\f(CW\*(C`INTEGER(KIND=1)\*(C'\fR, though a few as typeless, and at least one
-based on a command-line option specifying some kind of
-compatibility.
-.Ip "\fB\-fintrin-case-initcap\fR" 4
-.IX Item "-fintrin-case-initcap"
-.PD 0
-.Ip "\fB\-fintrin-case-upper\fR" 4
-.IX Item "-fintrin-case-upper"
-.Ip "\fB\-fintrin-case-lower\fR" 4
-.IX Item "-fintrin-case-lower"
-.Ip "\fB\-fintrin-case-any\fR" 4
-.IX Item "-fintrin-case-any"
-.PD
-Specify expected case for intrinsic names.
-\&\fB\-fintrin-case-lower\fR is the default.
-.Ip "\fB\-fmatch-case-initcap\fR" 4
-.IX Item "-fmatch-case-initcap"
-.PD 0
-.Ip "\fB\-fmatch-case-upper\fR" 4
-.IX Item "-fmatch-case-upper"
-.Ip "\fB\-fmatch-case-lower\fR" 4
-.IX Item "-fmatch-case-lower"
-.Ip "\fB\-fmatch-case-any\fR" 4
-.IX Item "-fmatch-case-any"
-.PD
-Specify expected case for keywords.
-\&\fB\-fmatch-case-lower\fR is the default.
-.Ip "\fB\-fsource-case-upper\fR" 4
-.IX Item "-fsource-case-upper"
-.PD 0
-.Ip "\fB\-fsource-case-lower\fR" 4
-.IX Item "-fsource-case-lower"
-.Ip "\fB\-fsource-case-preserve\fR" 4
-.IX Item "-fsource-case-preserve"
-.PD
-Specify whether source text other than character and Hollerith constants
-is to be translated to uppercase, to lowercase, or preserved as is.
-\&\fB\-fsource-case-lower\fR is the default.
-.Ip "\fB\-fsymbol-case-initcap\fR" 4
-.IX Item "-fsymbol-case-initcap"
-.PD 0
-.Ip "\fB\-fsymbol-case-upper\fR" 4
-.IX Item "-fsymbol-case-upper"
-.Ip "\fB\-fsymbol-case-lower\fR" 4
-.IX Item "-fsymbol-case-lower"
-.Ip "\fB\-fsymbol-case-any\fR" 4
-.IX Item "-fsymbol-case-any"
-.PD
-Specify valid cases for user-defined symbol names.
-\&\fB\-fsymbol-case-any\fR is the default.
-.Ip "\fB\-fcase-strict-upper\fR" 4
-.IX Item "-fcase-strict-upper"
-Same as \fB\-fintrin-case-upper \-fmatch-case-upper \-fsource-case-preserve
-\&\-fsymbol-case-upper\fR.
-(Requires all pertinent source to be in uppercase.)
-.Ip "\fB\-fcase-strict-lower\fR" 4
-.IX Item "-fcase-strict-lower"
-Same as \fB\-fintrin-case-lower \-fmatch-case-lower \-fsource-case-preserve
-\&\-fsymbol-case-lower\fR.
-(Requires all pertinent source to be in lowercase.)
-.Ip "\fB\-fcase-initcap\fR" 4
-.IX Item "-fcase-initcap"
-Same as \fB\-fintrin-case-initcap \-fmatch-case-initcap \-fsource-case-preserve
-\&\-fsymbol-case-initcap\fR.
-(Requires all pertinent source to be in initial capitals,
-as in \fBPrint *,SqRt(Value)\fR.)
-.Ip "\fB\-fcase-upper\fR" 4
-.IX Item "-fcase-upper"
-Same as \fB\-fintrin-case-any \-fmatch-case-any \-fsource-case-upper
-\&\-fsymbol-case-any\fR.
-(Maps all pertinent source to uppercase.)
-.Ip "\fB\-fcase-lower\fR" 4
-.IX Item "-fcase-lower"
-Same as \fB\-fintrin-case-any \-fmatch-case-any \-fsource-case-lower
-\&\-fsymbol-case-any\fR.
-(Maps all pertinent source to lowercase.)
-.Ip "\fB\-fcase-preserve\fR" 4
-.IX Item "-fcase-preserve"
-Same as \fB\-fintrin-case-any \-fmatch-case-any \-fsource-case-preserve
-\&\-fsymbol-case-any\fR.
-(Preserves all case in user-defined symbols,
-while allowing any-case matching of intrinsics and keywords.
-For example, \fBcall Foo(i,I)\fR would pass two \fIdifferent\fR
-variables named \fBi\fR and \fBI\fR to a procedure named \fBFoo\fR.)
-.Ip "\fB\-fbadu77\-intrinsics-delete\fR" 4
-.IX Item "-fbadu77-intrinsics-delete"
-.PD 0
-.Ip "\fB\-fbadu77\-intrinsics-hide\fR" 4
-.IX Item "-fbadu77-intrinsics-hide"
-.Ip "\fB\-fbadu77\-intrinsics-disable\fR" 4
-.IX Item "-fbadu77-intrinsics-disable"
-.Ip "\fB\-fbadu77\-intrinsics-enable\fR" 4
-.IX Item "-fbadu77-intrinsics-enable"
-.PD
-Specify status of \s-1UNIX\s0 intrinsics having inappropriate forms.
-\&\fB\-fbadu77\-intrinsics-enable\fR is the default.
-.Ip "\fB\-ff2c-intrinsics-delete\fR" 4
-.IX Item "-ff2c-intrinsics-delete"
-.PD 0
-.Ip "\fB\-ff2c-intrinsics-hide\fR" 4
-.IX Item "-ff2c-intrinsics-hide"
-.Ip "\fB\-ff2c-intrinsics-disable\fR" 4
-.IX Item "-ff2c-intrinsics-disable"
-.Ip "\fB\-ff2c-intrinsics-enable\fR" 4
-.IX Item "-ff2c-intrinsics-enable"
-.PD
-Specify status of f2c-specific intrinsics.
-\&\fB\-ff2c-intrinsics-enable\fR is the default.
-.Ip "\fB\-ff90\-intrinsics-delete\fR" 4
-.IX Item "-ff90-intrinsics-delete"
-.PD 0
-.Ip "\fB\-ff90\-intrinsics-hide\fR" 4
-.IX Item "-ff90-intrinsics-hide"
-.Ip "\fB\-ff90\-intrinsics-disable\fR" 4
-.IX Item "-ff90-intrinsics-disable"
-.Ip "\fB\-ff90\-intrinsics-enable\fR" 4
-.IX Item "-ff90-intrinsics-enable"
-.PD
-Specify status of F90\-specific intrinsics.
-\&\fB\-ff90\-intrinsics-enable\fR is the default.
-.Ip "\fB\-fgnu-intrinsics-delete\fR" 4
-.IX Item "-fgnu-intrinsics-delete"
-.PD 0
-.Ip "\fB\-fgnu-intrinsics-hide\fR" 4
-.IX Item "-fgnu-intrinsics-hide"
-.Ip "\fB\-fgnu-intrinsics-disable\fR" 4
-.IX Item "-fgnu-intrinsics-disable"
-.Ip "\fB\-fgnu-intrinsics-enable\fR" 4
-.IX Item "-fgnu-intrinsics-enable"
-.PD
-Specify status of Digital's COMPLEX-related intrinsics.
-\&\fB\-fgnu-intrinsics-enable\fR is the default.
-.Ip "\fB\-fmil-intrinsics-delete\fR" 4
-.IX Item "-fmil-intrinsics-delete"
-.PD 0
-.Ip "\fB\-fmil-intrinsics-hide\fR" 4
-.IX Item "-fmil-intrinsics-hide"
-.Ip "\fB\-fmil-intrinsics-disable\fR" 4
-.IX Item "-fmil-intrinsics-disable"
-.Ip "\fB\-fmil-intrinsics-enable\fR" 4
-.IX Item "-fmil-intrinsics-enable"
-.PD
-Specify status of MIL-STD-1753\-specific intrinsics.
-\&\fB\-fmil-intrinsics-enable\fR is the default.
-.Ip "\fB\-funix-intrinsics-delete\fR" 4
-.IX Item "-funix-intrinsics-delete"
-.PD 0
-.Ip "\fB\-funix-intrinsics-hide\fR" 4
-.IX Item "-funix-intrinsics-hide"
-.Ip "\fB\-funix-intrinsics-disable\fR" 4
-.IX Item "-funix-intrinsics-disable"
-.Ip "\fB\-funix-intrinsics-enable\fR" 4
-.IX Item "-funix-intrinsics-enable"
-.PD
-Specify status of \s-1UNIX\s0 intrinsics.
-\&\fB\-funix-intrinsics-enable\fR is the default.
-.Ip "\fB\-fvxt-intrinsics-delete\fR" 4
-.IX Item "-fvxt-intrinsics-delete"
-.PD 0
-.Ip "\fB\-fvxt-intrinsics-hide\fR" 4
-.IX Item "-fvxt-intrinsics-hide"
-.Ip "\fB\-fvxt-intrinsics-disable\fR" 4
-.IX Item "-fvxt-intrinsics-disable"
-.Ip "\fB\-fvxt-intrinsics-enable\fR" 4
-.IX Item "-fvxt-intrinsics-enable"
-.PD
-Specify status of \s-1VXT\s0 intrinsics.
-\&\fB\-fvxt-intrinsics-enable\fR is the default.
-.Ip "\fB\-ffixed-line-length-\fR\fIn\fR" 4
-.IX Item "-ffixed-line-length-n"
-Set column after which characters are ignored in typical fixed-form
-lines in the source file, and through which spaces are assumed (as
-if padded to that length) after the ends of short fixed-form lines.
-.Sp
-Popular values for \fIn\fR include 72 (the
-standard and the default), 80 (card image), and 132 (corresponds
-to ``extended-source'' options in some popular compilers).
-\&\fIn\fR may be \fBnone\fR, meaning that the entire line is meaningful
-and that continued character constants never have implicit spaces appended
-to them to fill out the line.
-\&\fB\-ffixed-line-length-0\fR means the same thing as
-\&\fB\-ffixed-line-length-none\fR.
-.Sh "Options to Request or Suppress Warnings"
-.IX Subsection "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
-might have been an error.
-.PP
-You can request many specific warnings with options beginning \fB\-W\fR,
-for example \fB\-Wimplicit\fR to request warnings on implicit
-declarations. Each of these specific warning options also has a
-negative form beginning \fB\-Wno-\fR to turn off warnings;
-for example, \fB\-Wno-implicit\fR. This manual lists only one of the
-two forms, whichever is not the default.
-.PP
-These options control the amount and kinds of warnings produced by \s-1GNU\s0
-Fortran:
-.Ip "\fB\-fsyntax-only\fR" 4
-.IX Item "-fsyntax-only"
-Check the code for syntax errors, but don't do anything beyond that.
-.Ip "\fB\-pedantic\fR" 4
-.IX Item "-pedantic"
-Issue warnings for uses of extensions to \s-1ANSI\s0 \s-1FORTRAN\s0 77.
-\&\fB\-pedantic\fR also applies to C-language constructs where they
-occur in \s-1GNU\s0 Fortran source files, such as use of \fB\ee\fR in a
-character constant within a directive like \fB#include\fR.
-.Sp
-Valid \s-1ANSI\s0 \s-1FORTRAN\s0 77 programs should compile properly with or without
-this option.
-However, without this option, certain \s-1GNU\s0 extensions and traditional
-Fortran features are supported as well.
-With this option, many of them are rejected.
-.Sp
-Some users try to use \fB\-pedantic\fR to check programs for strict \s-1ANSI\s0
-conformance.
-They soon find that it does not do quite what they want\-\-\-it finds some
-non-ANSI practices, but not all.
-However, improvements to \fBg77\fR in this area are welcome.
-.Ip "\fB\-pedantic-errors\fR" 4
-.IX Item "-pedantic-errors"
-Like \fB\-pedantic\fR, except that errors are produced rather than
-warnings.
-.Ip "\fB\-fpedantic\fR" 4
-.IX Item "-fpedantic"
-Like \fB\-pedantic\fR, but applies only to Fortran constructs.
-.Ip "\fB\-w\fR" 4
-.IX Item "-w"
-Inhibit all warning messages.
-.Ip "\fB\-Wno-globals\fR" 4
-.IX Item "-Wno-globals"
-Inhibit warnings about use of a name as both a global name
-(a subroutine, function, or block data program unit, or a
-common block) and implicitly as the name of an intrinsic
-in a source file.
-.Sp
-Also inhibit warnings about inconsistent invocations and/or
-definitions of global procedures (function and subroutines).
-Such inconsistencies include different numbers of arguments
-and different types of arguments.
-.Ip "\fB\-Wimplicit\fR" 4
-.IX Item "-Wimplicit"
-Warn whenever a variable, array, or function is implicitly
-declared.
-Has an effect similar to using the \f(CW\*(C`IMPLICIT NONE\*(C'\fR statement
-in every program unit.
-(Some Fortran compilers provide this feature by an option
-named \fB\-u\fR or \fB/WARNINGS=DECLARATIONS\fR.)
-.Ip "\fB\-Wunused\fR" 4
-.IX Item "-Wunused"
-Warn whenever a variable is unused aside from its declaration.
-.Ip "\fB\-Wuninitialized\fR" 4
-.IX Item "-Wuninitialized"
-Warn whenever an automatic variable is used without first being initialized.
-.Sp
-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 \fB\-O\fR, you simply won't
-get these warnings.
-.Sp
-These warnings occur only for variables that are candidates for
-register allocation. Therefore, they do not occur for a variable
-whose address is taken, or whose size
-is other than 1, 2, 4 or 8 bytes. Also, they do not occur for
-arrays, even when they are in registers.
-.Sp
-Note that there might 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.
-.Sp
-These warnings are made optional because \s-1GNU\s0 Fortran 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:
-.Sp
-.Vb 6
-\& SUBROUTINE DISPAT(J)
-\& IF (J.EQ.1) I=1
-\& IF (J.EQ.2) I=4
-\& IF (J.EQ.3) I=5
-\& CALL FOO(I)
-\& END
-.Ve
-If the value of \f(CW\*(C`J\*(C'\fR is always 1, 2 or 3, then \f(CW\*(C`I\*(C'\fR is
-always initialized, but \s-1GNU\s0 Fortran doesn't know this. Here is
-another common case:
-.Sp
-.Vb 6
-\& SUBROUTINE MAYBE(FLAG)
-\& LOGICAL FLAG
-\& IF (FLAG) VALUE = 9.4
-\& ...
-\& IF (FLAG) PRINT *, VALUE
-\& END
-.Ve
-This has no bug because \f(CW\*(C`VALUE\*(C'\fR is used only if it is set.
-.Ip "\fB\-Wall\fR" 4
-.IX Item "-Wall"
-The \fB\-Wunused\fR and \fB\-Wuninitialized\fR options combined.
-These are all the
-options which pertain to usage that we recommend avoiding and that we
-believe is easy to avoid.
-(As more warnings are added to \fBg77\fR some might
-be added to the list enabled by \fB\-Wall\fR.)
-.PP
-The remaining \fB\-W...\fR options are not implied by \fB\-Wall\fR
-because they warn about constructions that we consider reasonable to
-use, on occasion, in clean programs.
-.Ip "\fB\-Wsurprising\fR" 4
-.IX Item "-Wsurprising"
-Warn about ``suspicious'' constructs that are interpreted
-by the compiler in a way that might well be surprising to
-someone reading the code.
-These differences can result in subtle, compiler-dependent
-(even machine-dependent) behavioral differences.
-The constructs warned about include:
-.RS 4
-.Ip "\(bu" 4
-Expressions having two arithmetic operators in a row, such
-as \fBX*\-Y\fR.
-Such a construct is nonstandard, and can produce
-unexpected results in more complicated situations such
-as \fBX**\-Y*Z\fR.
-\&\fBg77\fR along with many other compilers, interprets
-this example differently than many programmers, and a few
-other compilers.
-Specifically, \fBg77\fR interprets \fBX**\-Y*Z\fR as
-\&\fB(X**(\-Y))*Z\fR, while others might think it should
-be interpreted as \fBX**(\-(Y*Z))\fR.
-.Sp
-A revealing example is the constant expression \fB2**\-2*1.\fR,
-which \fBg77\fR evaluates to .25, while others might evaluate
-it to 0., the difference resulting from the way precedence affects
-type promotion.
-.Sp
-(The \fB\-fpedantic\fR option also warns about expressions
-having two arithmetic operators in a row.)
-.Ip "\(bu" 4
-Expressions with a unary minus followed by an operand and then
-a binary operator other than plus or minus.
-For example, \fB\-2**2\fR produces a warning, because
-the precedence is \fB\-(2**2)\fR, yielding \-4, not
-\&\fB(\-2)**2\fR, which yields 4, and which might represent
-what a programmer expects.
-.Sp
-An example of an expression producing different results
-in a surprising way is \fB\-I*S\fR, where \fII\fR holds
-the value \fB\-2147483648\fR and \fIS\fR holds \fB0.5\fR.
-On many systems, negating \fII\fR results in the same
-value, not a positive number, because it is already the
-lower bound of what an \f(CW\*(C`INTEGER(KIND=1)\*(C'\fR variable can hold.
-So, the expression evaluates to a positive number, while
-the ``expected'' interpretation, \fB(\-I)*S\fR, would
-evaluate to a negative number.
-.Sp
-Even cases such as \fB\-I*J\fR produce warnings,
-even though, in most configurations and situations,
-there is no computational difference between the
-results of the two interpretations\-\-\-the purpose
-of this warning is to warn about differing interpretations
-and encourage a better style of coding, not to identify
-only those places where bugs might exist in the user's
-code.
-.Ip "\(bu" 4
-\&\f(CW\*(C`DO\*(C'\fR loops with \f(CW\*(C`DO\*(C'\fR variables that are not
-of integral type\-\-\-that is, using \f(CW\*(C`REAL\*(C'\fR
-variables as loop control variables.
-Although such loops can be written to work in the
-``obvious'' way, the way \fBg77\fR is required by the
-Fortran standard to interpret such code is likely to
-be quite different from the way many programmers expect.
-(This is true of all \f(CW\*(C`DO\*(C'\fR loops, but the differences
-are pronounced for non-integral loop control variables.)
-.RE
-.RS 4
-.RE
-.Ip "\fB\-Werror\fR" 4
-.IX Item "-Werror"
-Make all warnings into errors.
-.Ip "\fB\-W\fR" 4
-.IX Item "-W"
-Turns on ``extra warnings'' and, if optimization is specified
-via \fB\-O\fR, the \fB\-Wuninitialized\fR option.
-(This might change in future versions of \fBg77\fR
-.Sp
-``Extra warnings'' are issued for:
-.RS 4
-.Ip "\(bu" 4
-Unused parameters to a procedure (when \fB\-Wunused\fR also is
-specified).
-.Ip "\(bu" 4
-Overflows involving floating-point constants (not available
-for certain configurations).
-.RE
-.RS 4
-.RE
-.PP
-Some of these have no effect when compiling programs written in Fortran:
-.Ip "\fB\-Wcomment\fR" 4
-.IX Item "-Wcomment"
-.PD 0
-.Ip "\fB\-Wformat\fR" 4
-.IX Item "-Wformat"
-.Ip "\fB\-Wparentheses\fR" 4
-.IX Item "-Wparentheses"
-.Ip "\fB\-Wswitch\fR" 4
-.IX Item "-Wswitch"
-.Ip "\fB\-Wtraditional\fR" 4
-.IX Item "-Wtraditional"
-.Ip "\fB\-Wshadow\fR" 4
-.IX Item "-Wshadow"
-.Ip "\fB\-Wid-clash-\fR\fIlen\fR" 4
-.IX Item "-Wid-clash-len"
-.Ip "\fB\-Wlarger-than-\fR\fIlen\fR" 4
-.IX Item "-Wlarger-than-len"
-.Ip "\fB\-Wconversion\fR" 4
-.IX Item "-Wconversion"
-.Ip "\fB\-Waggregate-return\fR" 4
-.IX Item "-Waggregate-return"
-.Ip "\fB\-Wredundant-decls\fR" 4
-.IX Item "-Wredundant-decls"
-.PD
-These options all could have some relevant meaning for
-\&\s-1GNU\s0 Fortran programs, but are not yet supported.
-.Sh "Options for Debugging Your Program or \s-1GNU\s0 Fortran"
-.IX Subsection "Options for Debugging Your Program or GNU Fortran"
-\&\s-1GNU\s0 Fortran has various special options that are used for debugging
-either your program or \fBg77\fR
-.Ip "\fB\-g\fR" 4
-.IX Item "-g"
-Produce debugging information in the operating system's native format
-(stabs, \s-1COFF\s0, \s-1XCOFF\s0, or \s-1DWARF\s0). \s-1GDB\s0 can work with this debugging
-information.
-.Sp
-A sample debugging session looks like this (note the use of the breakpoint):
-.Sp
-.Vb 24
-\& $ cat gdb.f
-\& PROGRAM PROG
-\& DIMENSION A(10)
-\& DATA A /1.,2.,3.,4.,5.,6.,7.,8.,9.,10./
-\& A(5) = 4.
-\& PRINT*,A
-\& END
-\& $ g77 -g -O gdb.f
-\& $ gdb a.out
-\& ...
-\& (gdb) break MAIN__
-\& Breakpoint 1 at 0x8048e96: file gdb.f, line 4.
-\& (gdb) run
-\& Starting program: /home/toon/g77-bugs/./a.out
-\& Breakpoint 1, MAIN__ () at gdb.f:4
-\& 4 A(5) = 4.
-\& Current language: auto; currently fortran
-\& (gdb) print a(5)
-\& $1 = 5
-\& (gdb) step
-\& 5 PRINT*,A
-\& (gdb) print a(5)
-\& $2 = 4
-\& ...
-.Ve
-One could also add the setting of the breakpoint and the first run command
-to the file \fI.gdbinit\fR in the current directory, to simplify the debugging
-session.
-.Sh "Options That Control Optimization"
-.IX Subsection "Options That Control Optimization"
-Most Fortran users will want to use no optimization when
-developing and testing programs, and use \fB\-O\fR or \fB\-O2\fR when
-compiling programs for late-cycle testing and for production use.
-However, note that certain diagnostics\-\-\-such as for uninitialized
-variables\-\-\-depend on the flow analysis done by \fB\-O\fR, i.e. you
-must use \fB\-O\fR or \fB\-O2\fR to get such diagnostics.
-.PP
-The following flags have particular applicability when
-compiling Fortran programs:
-.Ip "\fB\-malign-double\fR" 4
-.IX Item "-malign-double"
-(Intel x86 architecture only.)
-.Sp
-Noticeably improves performance of \fBg77\fR programs making
-heavy use of \f(CW\*(C`REAL(KIND=2)\*(C'\fR (\f(CW\*(C`DOUBLE PRECISION\*(C'\fR) data
-on some systems.
-In particular, systems using Pentium, Pentium Pro, 586, and
-686 implementations
-of the i386 architecture execute programs faster when
-\&\f(CW\*(C`REAL(KIND=2)\*(C'\fR (\f(CW\*(C`DOUBLE PRECISION\*(C'\fR) data are
-aligned on 64\-bit boundaries
-in memory.
-.Sp
-This option can, at least, make benchmark results more consistent
-across various system configurations, versions of the program,
-and data sets.
-.Sp
-\&\fINote:\fR The warning in the \fBgcc\fR documentation about
-this option does not apply, generally speaking, to Fortran
-code compiled by \fBg77\fR
-.Sp
-\&\fIAlso also note:\fR The negative form of \fB\-malign-double\fR
-is \fB\-mno-align-double\fR, not \fB\-benign-double\fR.
-.Ip "\fB\-ffloat-store\fR" 4
-.IX Item "-ffloat-store"
-Might help a Fortran program that depends on exact \s-1IEEE\s0 conformance on
-some machines, but might slow down a program that doesn't.
-.Sp
-This option is effective when the floating-point unit is set to work in
-\&\s-1IEEE\s0 854 `extended precision'\-\-\-as it typically is on x86 and m68k \s-1GNU\s0
-systems\-\-\-rather than \s-1IEEE\s0 754 double precision. \fB\-ffloat-store\fR
-tries to remove the extra precision by spilling data from floating-point
-registers into memory and this typically involves a big performance
-hit. However, it doesn't affect intermediate results, so that it is
-only partially effective. `Excess precision' is avoided in code like:
-.Sp
-.Vb 2
-\& a = b + c
-\& d = a * e
-.Ve
-but not in code like:
-.Sp
-.Vb 1
-\& d = (b + c) * e
-.Ve
-For another, potentially better, way of controlling the precision,
-see \f(CW@ref\fR{Floating-point precision}.
-.Ip "\fB\-fforce-mem\fR" 4
-.IX Item "-fforce-mem"
-.PD 0
-.Ip "\fB\-fforce-addr\fR" 4
-.IX Item "-fforce-addr"
-.PD
-Might improve optimization of loops.
-.Ip "\fB\-fno-inline\fR" 4
-.IX Item "-fno-inline"
-Don't compile statement functions inline.
-Might reduce the size of a program unit\-\-\-which might be at
-expense of some speed (though it should compile faster).
-Note that if you are not optimizing, no functions can be expanded inline.
-.Ip "\fB\-ffast-math\fR" 4
-.IX Item "-ffast-math"
-Might allow some programs designed to not be too dependent
-on \s-1IEEE\s0 behavior for floating-point to run faster, or die trying.
-Sets \fB\-funsafe-math-optimizations\fR, and
-\&\fB\-fno-trapping-math\fR.
-.Ip "\fB\-funsafe-math-optimizations\fR" 4
-.IX Item "-funsafe-math-optimizations"
-Allow optimizations that may be give incorrect results
-for certain \s-1IEEE\s0 inputs.
-.Ip "\fB\-fno-trapping-math\fR" 4
-.IX Item "-fno-trapping-math"
-Allow the compiler to assume that floating-point arithmetic
-will not generate traps on any inputs. This is useful, for
-example, when running a program using \s-1IEEE\s0 \*(L"non-stop\*(R"
-floating-point arithmetic.
-.Ip "\fB\-fstrength-reduce\fR" 4
-.IX Item "-fstrength-reduce"
-Might make some loops run faster.
-.Ip "\fB\-frerun-cse-after-loop\fR" 4
-.IX Item "-frerun-cse-after-loop"
-.PD 0
-.Ip "\fB\-fexpensive-optimizations\fR" 4
-.IX Item "-fexpensive-optimizations"
-.Ip "\fB\-fdelayed-branch\fR" 4
-.IX Item "-fdelayed-branch"
-.Ip "\fB\-fschedule-insns\fR" 4
-.IX Item "-fschedule-insns"
-.Ip "\fB\-fschedule-insns2\fR" 4
-.IX Item "-fschedule-insns2"
-.Ip "\fB\-fcaller-saves\fR" 4
-.IX Item "-fcaller-saves"
-.PD
-Might improve performance on some code.
-.Ip "\fB\-funroll-loops\fR" 4
-.IX Item "-funroll-loops"
-Typically improves performance on code using iterative \f(CW\*(C`DO\*(C'\fR loops by
-unrolling them and is probably generally appropriate for Fortran, though
-it is not turned on at any optimization level.
-Note that outer loop unrolling isn't done specifically; decisions about
-whether to unroll a loop are made on the basis of its instruction count.
-.Sp
-Also, no `loop discovery'[1] is done, so only loops written with \f(CW\*(C`DO\*(C'\fR
-benefit from loop optimizations, including\-\-\-but not limited
-to\-\-\-unrolling. Loops written with \f(CW\*(C`IF\*(C'\fR and \f(CW\*(C`GOTO\*(C'\fR are not
-currently recognized as such. This option unrolls only iterative
-\&\f(CW\*(C`DO\*(C'\fR loops, not \f(CW\*(C`DO WHILE\*(C'\fR loops.
-.Ip "\fB\-funroll-all-loops\fR" 4
-.IX Item "-funroll-all-loops"
-Probably improves performance on code using \f(CW\*(C`DO WHILE\*(C'\fR loops by
-unrolling them in addition to iterative \f(CW\*(C`DO\*(C'\fR loops. In the absence
-of \f(CW\*(C`DO WHILE\*(C'\fR, this option is equivalent to \fB\-funroll-loops\fR
-but possibly slower.
-.Ip "\fB\-fno-move-all-movables\fR" 4
-.IX Item "-fno-move-all-movables"
-.PD 0
-.Ip "\fB\-fno-reduce-all-givs\fR" 4
-.IX Item "-fno-reduce-all-givs"
-.Ip "\fB\-fno-rerun-loop-opt\fR" 4
-.IX Item "-fno-rerun-loop-opt"
-.PD
-In general, the optimizations enabled with these options will lead to
-faster code being generated by \s-1GNU\s0 Fortran; hence they are enabled by default
-when issuing the \fBg77\fR command.
-.Sp
-\&\fB\-fmove-all-movables\fR and \fB\-freduce-all-givs\fR will enable
-loop optimization to move all loop-invariant index computations in nested
-loops over multi-rank array dummy arguments out of these loops.
-.Sp
-\&\fB\-frerun-loop-opt\fR will move offset calculations resulting
-from the fact that Fortran arrays by default have a lower bound of 1
-out of the loops.
-.Sp
-These three options are intended to be removed someday, once
-loop optimization is sufficiently advanced to perform all those
-transformations without help from these options.
-.Sh "Options Controlling the Preprocessor"
-.IX Subsection "Options Controlling the Preprocessor"
-These options control the C preprocessor, which is run on each C source
-file before actual compilation.
-.PP
-Some of these options also affect how \fBg77\fR processes the
-\&\f(CW\*(C`INCLUDE\*(C'\fR directive.
-Since this directive is processed even when preprocessing
-is not requested, it is not described in this section.
-.PP
-However, the \f(CW\*(C`INCLUDE\*(C'\fR directive does not apply
-preprocessing to the contents of the included file itself.
-.PP
-Therefore, any file that contains preprocessor directives
-(such as \f(CW\*(C`#include\*(C'\fR, \f(CW\*(C`#define\*(C'\fR, and \f(CW\*(C`#if\*(C'\fR)
-must be included via the \f(CW\*(C`#include\*(C'\fR directive, not
-via the \f(CW\*(C`INCLUDE\*(C'\fR directive.
-Therefore, any file containing preprocessor directives,
-if included, is necessarily included by a file that itself
-contains preprocessor directives.
-.Sh "Options for Directory Search"
-.IX Subsection "Options for Directory Search"
-These options affect how the \fBcpp\fR preprocessor searches
-for files specified via the \f(CW\*(C`#include\*(C'\fR directive.
-Therefore, when compiling Fortran programs, they are meaningful
-when the preprocessor is used.
-.PP
-Some of these options also affect how \fBg77\fR searches
-for files specified via the \f(CW\*(C`INCLUDE\*(C'\fR directive,
-although files included by that directive are not,
-themselves, preprocessed.
-These options are:
-.Ip "\fB\-I-\fR" 4
-.IX Item "-I-"
-.PD 0
-.Ip "\fB\-I\fR\fIdir\fR" 4
-.IX Item "-Idir"
-.PD
-These affect interpretation of the \f(CW\*(C`INCLUDE\*(C'\fR directive
-(as well as of the \f(CW\*(C`#include\*(C'\fR directive of the \fBcpp\fR
-preprocessor).
-.Sp
-Note that \fB\-I\fR\fIdir\fR must be specified \fIwithout\fR any
-spaces between \fB\-I\fR and the directory name\-\-\-that is,
-\&\fB\-Ifoo/bar\fR is valid, but \fB\-I foo/bar\fR
-is rejected by the \fBg77\fR compiler (though the preprocessor supports
-the latter form).
-Also note that the general behavior of \fB\-I\fR and
-\&\f(CW\*(C`INCLUDE\*(C'\fR is pretty much the same as of \fB\-I\fR with
-\&\f(CW\*(C`#include\*(C'\fR in the \fBcpp\fR preprocessor, with regard to
-looking for \fIheader.gcc\fR files and other such things.
-.Sh "Options for Code Generation Conventions"
-.IX Subsection "Options for Code Generation Conventions"
-These machine-independent options control the interface conventions
-used in code generation.
-.PP
-Most of them have both positive and negative forms; the negative form
-of \fB\-ffoo\fR would be \fB\-fno-foo\fR. 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 \fBno-\fR or adding
-it.
-.Ip "\fB\-fno-automatic\fR" 4
-.IX Item "-fno-automatic"
-Treat each program unit as if the \f(CW\*(C`SAVE\*(C'\fR statement was specified
-for every local variable and array referenced in it.
-Does not affect common blocks.
-(Some Fortran compilers provide this option under
-the name \fB\-static\fR.)
-.Ip "\fB\-finit-local-zero\fR" 4
-.IX Item "-finit-local-zero"
-Specify that variables and arrays that are local to a program unit
-(not in a common block and not passed as an argument) are to be initialized
-to binary zeros.
-.Sp
-Since there is a run-time penalty for initialization of variables
-that are not given the \f(CW\*(C`SAVE\*(C'\fR attribute, it might be a
-good idea to also use \fB\-fno-automatic\fR with \fB\-finit-local-zero\fR.
-.Ip "\fB\-fno-f2c\fR" 4
-.IX Item "-fno-f2c"
-Do not generate code designed to be compatible with code generated
-by \fBf2c\fR use the \s-1GNU\s0 calling conventions instead.
-.Sp
-The \fBf2c\fR calling conventions require functions that return
-type \f(CW\*(C`REAL(KIND=1)\*(C'\fR to actually return the C type \f(CW\*(C`double\*(C'\fR,
-and functions that return type \f(CW\*(C`COMPLEX\*(C'\fR to return the
-values via an extra argument in the calling sequence that points
-to where to store the return value.
-Under the \s-1GNU\s0 calling conventions, such functions simply return
-their results as they would in \s-1GNU\s0 C\-\--\f(CW\*(C`REAL(KIND=1)\*(C'\fR functions
-return the C type \f(CW\*(C`float\*(C'\fR, and \f(CW\*(C`COMPLEX\*(C'\fR functions
-return the \s-1GNU\s0 C type \f(CW\*(C`complex\*(C'\fR (or its \f(CW\*(C`struct\*(C'\fR
-equivalent).
-.Sp
-This does not affect the generation of code that interfaces with the
-\&\f(CW\*(C`libg2c\*(C'\fR library.
-.Sp
-However, because the \f(CW\*(C`libg2c\*(C'\fR library uses \fBf2c\fR
-calling conventions, \fBg77\fR rejects attempts to pass
-intrinsics implemented by routines in this library as actual
-arguments when \fB\-fno-f2c\fR is used, to avoid bugs when
-they are actually called by code expecting the \s-1GNU\s0 calling
-conventions to work.
-.Sp
-For example, \fB\s-1INTRINSIC\s0 \s-1ABS\s0;CALL FOO(\s-1ABS\s0)\fR is
-rejected when \fB\-fno-f2c\fR is in force.
-(Future versions of the \fBg77\fR run-time library might
-offer routines that provide GNU-callable versions of the
-routines that implement the \fBf2c\fR intrinsics
-that may be passed as actual arguments, so that
-valid programs need not be rejected when \fB\-fno-f2c\fR
-is used.)
-.Sp
-\&\fBCaution:\fR If \fB\-fno-f2c\fR is used when compiling any
-source file used in a program, it must be used when compiling
-\&\fIall\fR Fortran source files used in that program.
-.Ip "\fB\-ff2c-library\fR" 4
-.IX Item "-ff2c-library"
-Specify that use of \f(CW\*(C`libg2c\*(C'\fR (or the original \f(CW\*(C`libf2c\*(C'\fR)
-is required.
-This is the default for the current version of \fBg77\fR
-.Sp
-Currently it is not
-valid to specify \fB\-fno-f2c-library\fR.
-This option is provided so users can specify it in shell
-scripts that build programs and libraries that require the
-\&\f(CW\*(C`libf2c\*(C'\fR library, even when being compiled by future
-versions of \fBg77\fR that might otherwise default to
-generating code for an incompatible library.
-.Ip "\fB\-fno-underscoring\fR" 4
-.IX Item "-fno-underscoring"
-Do not transform names of entities specified in the Fortran
-source file by appending underscores to them.
-.Sp
-With \fB\-funderscoring\fR in effect, \fBg77\fR appends two underscores
-to names with underscores and one underscore to external names with
-no underscores. (\fBg77\fR also appends two underscores to internal
-names with underscores to avoid naming collisions with external names.
-The \fB\-fno-second-underscore\fR option disables appending of the
-second underscore in all cases.)
-.Sp
-This is done to ensure compatibility with code produced by many
-\&\s-1UNIX\s0 Fortran compilers, including \fBf2c\fR which perform the
-same transformations.
-.Sp
-Use of \fB\-fno-underscoring\fR is not recommended unless you are
-experimenting with issues such as integration of (\s-1GNU\s0) Fortran into
-existing system environments (vis-a-vis existing libraries, tools, and
-so on).
-.Sp
-For example, with \fB\-funderscoring\fR, and assuming other defaults like
-\&\fB\-fcase-lower\fR and that \fB\f(BIj()\fB\fR and \fB\f(BImax_count()\fB\fR are
-external functions while \fBmy_var\fR and \fBlvar\fR are local variables,
-a statement like
-.Sp
-.Vb 1
-\& I = J() + MAX_COUNT (MY_VAR, LVAR)
-.Ve
-is implemented as something akin to:
-.Sp
-.Vb 1
-\& i = j_() + max_count__(&my_var__, &lvar);
-.Ve
-With \fB\-fno-underscoring\fR, the same statement is implemented as:
-.Sp
-.Vb 1
-\& i = j() + max_count(&my_var, &lvar);
-.Ve
-Use of \fB\-fno-underscoring\fR allows direct specification of
-user-defined names while debugging and when interfacing \fBg77\fR
-code with other languages.
-.Sp
-Note that just because the names match does \fInot\fR mean that the
-interface implemented by \fBg77\fR for an external name matches the
-interface implemented by some other language for that same name.
-That is, getting code produced by \fBg77\fR to link to code produced
-by some other compiler using this or any other method can be only a
-small part of the overall solution\-\-\-getting the code generated by
-both compilers to agree on issues other than naming can require
-significant effort, and, unlike naming disagreements, linkers normally
-cannot detect disagreements in these other areas.
-.Sp
-Also, note that with \fB\-fno-underscoring\fR, the lack of appended
-underscores introduces the very real possibility that a user-defined
-external name will conflict with a name in a system library, which
-could make finding unresolved-reference bugs quite difficult in some
-cases\-\-\-they might occur at program run time, and show up only as
-buggy behavior at run time.
-.Sp
-In future versions of \fBg77\fR we hope to improve naming and linking
-issues so that debugging always involves using the names as they appear
-in the source, even if the names as seen by the linker are mangled to
-prevent accidental linking between procedures with incompatible
-interfaces.
-.Ip "\fB\-fno-second-underscore\fR" 4
-.IX Item "-fno-second-underscore"
-Do not append a second underscore to names of entities specified
-in the Fortran source file.
-.Sp
-This option has no effect if \fB\-fno-underscoring\fR is
-in effect.
-.Sp
-Otherwise, with this option, an external name such as \fB\s-1MAX_COUNT\s0\fR
-is implemented as a reference to the link-time external symbol
-\&\fBmax_count_\fR, instead of \fBmax_count_\|_\fR.
-.Ip "\fB\-fno-ident\fR" 4
-.IX Item "-fno-ident"
-Ignore the \fB#ident\fR directive.
-.Ip "\fB\-fzeros\fR" 4
-.IX Item "-fzeros"
-Treat initial values of zero as if they were any other value.
-.Sp
-As of version 0.5.18, \fBg77\fR normally treats \f(CW\*(C`DATA\*(C'\fR and
-other statements that are used to specify initial values of zero
-for variables and arrays as if no values were actually specified,
-in the sense that no diagnostics regarding multiple initializations
-are produced.
-.Sp
-This is done to speed up compiling of programs that initialize
-large arrays to zeros.
-.Sp
-Use \fB\-fzeros\fR to revert to the simpler, slower behavior
-that can catch multiple initializations by keeping track of
-all initializations, zero or otherwise.
-.Sp
-\&\fICaution:\fR Future versions of \fBg77\fR might disregard this option
-(and its negative form, the default) or interpret it somewhat
-differently.
-The interpretation changes will affect only non-standard
-programs; standard-conforming programs should not be affected.
-.Ip "\fB\-femulate-complex\fR" 4
-.IX Item "-femulate-complex"
-Implement \f(CW\*(C`COMPLEX\*(C'\fR arithmetic via emulation,
-instead of using the facilities of
-the \fBgcc\fR back end that provide direct support of
-\&\f(CW\*(C`complex\*(C'\fR arithmetic.
-.Sp
-(\fBgcc\fR had some bugs in its back-end support
-for \f(CW\*(C`complex\*(C'\fR arithmetic, due primarily to the support not being
-completed as of version 2.8.1 and \f(CW\*(C`egcs\*(C'\fR 1.1.2.)
-.Sp
-Use \fB\-femulate-complex\fR if you suspect code-generation bugs,
-or experience compiler crashes,
-that might result from \fBg77\fR using the \f(CW\*(C`COMPLEX\*(C'\fR support
-in the \fBgcc\fR back end.
-If using that option fixes the bugs or crashes you are seeing,
-that indicates a likely \fBg77\fR bugs
-(though, all compiler crashes are considered bugs),
-so, please report it.
-(Note that the known bugs, now believed fixed, produced compiler crashes
-rather than causing the generation of incorrect code.)
-.Sp
-Use of this option should not affect how Fortran code compiled
-by \fBg77\fR works in terms of its interfaces to other code,
-e.g. that compiled by \fBf2c\fR
-.Sp
-As of \s-1GCC\s0 version 3.0, this option is not necessary anymore.
-.Sp
-\&\fICaution:\fR Future versions of \fBg77\fR might ignore both forms
-of this option.
-.Ip "\fB\-falias-check\fR" 4
-.IX Item "-falias-check"
-.PD 0
-.Ip "\fB\-fargument-alias\fR" 4
-.IX Item "-fargument-alias"
-.Ip "\fB\-fargument-noalias\fR" 4
-.IX Item "-fargument-noalias"
-.Ip "\fB\-fno-argument-noalias-global\fR" 4
-.IX Item "-fno-argument-noalias-global"
-.PD
-\&\fIVersion info:\fR
-These options are not supported by
-versions of \fBg77\fR based on \fBgcc\fR version 2.8.
-.Sp
-These options specify to what degree aliasing
-(overlap)
-is permitted between
-arguments (passed as pointers) and \f(CW\*(C`COMMON\*(C'\fR (external, or
-public) storage.
-.Sp
-The default for Fortran code, as mandated by the \s-1FORTRAN\s0 77 and
-Fortran 90 standards, is \fB\-fargument-noalias-global\fR.
-The default for code written in the C language family is
-\&\fB\-fargument-alias\fR.
-.Sp
-Note that, on some systems, compiling with \fB\-fforce-addr\fR in
-effect can produce more optimal code when the default aliasing
-options are in effect (and when optimization is enabled).
-.Ip "\fB\-fno-globals\fR" 4
-.IX Item "-fno-globals"
-Disable diagnostics about inter-procedural
-analysis problems, such as disagreements about the
-type of a function or a procedure's argument,
-that might cause a compiler crash when attempting
-to inline a reference to a procedure within a
-program unit.
-(The diagnostics themselves are still produced, but
-as warnings, unless \fB\-Wno-globals\fR is specified,
-in which case no relevant diagnostics are produced.)
-.Sp
-Further, this option disables such inlining, to
-avoid compiler crashes resulting from incorrect
-code that would otherwise be diagnosed.
-.Sp
-As such, this option might be quite useful when
-compiling existing, ``working'' code that happens
-to have a few bugs that do not generally show themselves,
-but which \fBg77\fR diagnoses.
-.Sp
-Use of this option therefore has the effect of
-instructing \fBg77\fR to behave more like it did
-up through version 0.5.19.1, when it paid little or
-no attention to disagreements between program units
-about a procedure's type and argument information,
-and when it performed no inlining of procedures
-(except statement functions).
-.Sp
-Without this option, \fBg77\fR defaults to performing
-the potentially inlining procedures as it started doing
-in version 0.5.20, but as of version 0.5.21, it also
-diagnoses disagreements that might cause such inlining
-to crash the compiler as (fatal) errors,
-and warns about similar disagreements
-that are currently believed to not
-likely to result in the compiler later crashing
-or producing incorrect code.
-.Ip "\fB\-fflatten-arrays\fR" 4
-.IX Item "-fflatten-arrays"
-Use back end's C-like constructs
-(pointer plus offset)
-instead of its \f(CW\*(C`ARRAY_REF\*(C'\fR construct
-to handle all array references.
-.Sp
-\&\fINote:\fR This option is not supported.
-It is intended for use only by \fBg77\fR developers,
-to evaluate code-generation issues.
-It might be removed at any time.
-.Ip "\fB\-fbounds-check\fR" 4
-.IX Item "-fbounds-check"
-.PD 0
-.Ip "\fB\-ffortran-bounds-check\fR" 4
-.IX Item "-ffortran-bounds-check"
-.PD
-Enable generation of run-time checks for array subscripts
-and substring start and end points
-against the (locally) declared minimum and maximum values.
-.Sp
-The current implementation uses the \f(CW\*(C`libf2c\*(C'\fR
-library routine \f(CW\*(C`s_rnge\*(C'\fR to print the diagnostic.
-.Sp
-However, whereas \fBf2c\fR generates a single check per
-reference for a multi-dimensional array, of the computed
-offset against the valid offset range (0 through the size of the array),
-\&\fBg77\fR generates a single check per \fIsubscript\fR expression.
-This catches some cases of potential bugs that \fBf2c\fR does not,
-such as references to below the beginning of an assumed-size array.
-.Sp
-\&\fBg77\fR also generates checks for \f(CW\*(C`CHARACTER\*(C'\fR substring references,
-something \fBf2c\fR currently does not do.
-.Sp
-Use the new \fB\-ffortran-bounds-check\fR option
-to specify bounds-checking for only the Fortran code you are compiling,
-not necessarily for code written in other languages.
-.Sp
-\&\fINote:\fR To provide more detailed information on the offending subscript,
-\&\fBg77\fR provides the \f(CW\*(C`libg2c\*(C'\fR run-time library routine \f(CW\*(C`s_rnge\*(C'\fR
-with somewhat differently-formatted information.
-Here's a sample diagnostic:
-.Sp
-.Vb 3
-\& Subscript out of range on file line 4, procedure rnge.f/bf.
-\& Attempt to access the -6-th element of variable b[subscript-2-of-2].
-\& Aborted
-.Ve
-The above message indicates that the offending source line is
-line 4 of the file \fIrnge.f\fR,
-within the program unit (or statement function) named \fBbf\fR.
-The offended array is named \fBb\fR.
-The offended array dimension is the second for a two-dimensional array,
-and the offending, computed subscript expression was \fB\-6\fR.
-.Sp
-For a \f(CW\*(C`CHARACTER\*(C'\fR substring reference, the second line has
-this appearance:
-.Sp
-.Vb 1
-\& Attempt to access the 11-th element of variable a[start-substring].
-.Ve
-This indicates that the offended \f(CW\*(C`CHARACTER\*(C'\fR variable or array
-is named \fBa\fR,
-the offended substring position is the starting (leftmost) position,
-and the offending substring expression is \fB11\fR.
-.Sp
-(Though the verbage of \f(CW\*(C`s_rnge\*(C'\fR is not ideal
-for the purpose of the \fBg77\fR compiler,
-the above information should provide adequate diagnostic abilities
-to it users.)
-.PP
-Some of these do \fInot\fR work when compiling programs written in Fortran:
-.Ip "\fB\-fpcc-struct-return\fR" 4
-.IX Item "-fpcc-struct-return"
-.PD 0
-.Ip "\fB\-freg-struct-return\fR" 4
-.IX Item "-freg-struct-return"
-.PD
-You should not use these except strictly the same way as you
-used them to build the version of \f(CW\*(C`libg2c\*(C'\fR with which
-you will be linking all code compiled by \fBg77\fR with the
-same option.
-.Ip "\fB\-fshort-double\fR" 4
-.IX Item "-fshort-double"
-This probably either has no effect on Fortran programs, or
-makes them act loopy.
-.Ip "\fB\-fno-common\fR" 4
-.IX Item "-fno-common"
-Do not use this when compiling Fortran programs,
-or there will be Trouble.
-.Ip "\fB\-fpack-struct\fR" 4
-.IX Item "-fpack-struct"
-This probably will break any calls to the \f(CW\*(C`libg2c\*(C'\fR library,
-at the very least, even if it is built with the same option.
-.SH "ENVIRONMENT"
-.IX Header "ENVIRONMENT"
-\&\s-1GNU\s0 Fortran currently does not make use of any environment
-variables to control its operation above and beyond those
-that affect the operation of \fBgcc\fR.
-.SH "BUGS"
-.IX Header "BUGS"
-For instructions on reporting bugs, see
-<\fBhttp://gcc.gnu.org/bugs.html\fR>. Use of the \fBgccbug\fR
-script to report bugs is recommended.
-.SH "FOOTNOTES"
-.IX Header "FOOTNOTES"
-.Ip "1." 4
-\&\fIloop discovery\fR refers to the
-process by which a compiler, or indeed any reader of a program,
-determines which portions of the program are more likely to be executed
-repeatedly as it is being run. Such discovery typically is done early
-when compiling using optimization techniques, so the ``discovered''
-loops get more attention\-\-\-and more run-time resources, such as
-registers\-\-\-from the compiler. It is easy to ``discover'' loops that are
-constructed out of looping constructs in the language
-(such as Fortran's \f(CW\*(C`DO\*(C'\fR). For some programs, ``discovering'' loops
-constructed out of lower-level constructs (such as \f(CW\*(C`IF\*(C'\fR and
-\&\f(CW\*(C`GOTO\*(C'\fR) can lead to generation of more optimal code
-than otherwise.
-.SH "SEE ALSO"
-.IX Header "SEE ALSO"
-\&\fIgpl\fR\|(7), \fIgfdl\fR\|(7), \fIfsf-funding\fR\|(7),
-\&\fIcpp\fR\|(1), \fIgcov\fR\|(1), \fIgcc\fR\|(1), \fIas\fR\|(1), \fIld\fR\|(1), \fIgdb\fR\|(1), \fIadb\fR\|(1), \fIdbx\fR\|(1), \fIsdb\fR\|(1)
-and the Info entries for \fIgcc\fR, \fIcpp\fR, \fIg77\fR, \fIas\fR,
-\&\fIld\fR, \fIbinutils\fR and \fIgdb\fR.
-.SH "AUTHOR"
-.IX Header "AUTHOR"
-See the Info entry for \fBg77\fR for contributors to \s-1GCC\s0 and G77.
-.SH "COPYRIGHT"
-.IX Header "COPYRIGHT"
-Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002
-Free Software Foundation, Inc.
-.PP
-Permission is granted to copy, distribute and/or modify this document
-under the terms of the \s-1GNU\s0 Free Documentation License, Version 1.1 or
-any later version published by the Free Software Foundation; with the
-Invariant Sections being ``\s-1GNU\s0 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 \fIgfdl\fR\|(7) man page.
-.PP
-(a) The \s-1FSF\s0's Front-Cover Text is:
-.PP
-.Vb 1
-\& A GNU Manual
-.Ve
-(b) The \s-1FSF\s0's Back-Cover Text is:
-.PP
-.Vb 3
-\& 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.
-.Ve
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