-@c Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001
+@c Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2004
@c Free Software Foundation, Inc.
@c This is part of the G77 manual.
@c For copying conditions, see the file g77.texi.
@ignore
@c man begin COPYRIGHT
-Copyright @copyright{} 1996, 1997, 1998, 1999, 2000, 2001
+Copyright @copyright{} 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2004
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
+under the terms of the GNU Free Documentation License, Version 1.2 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
script to report bugs is recommended.
@c man end
@c man begin AUTHOR
-See the Info entry for @file{g77}, or
-@w{@uref{http://gcc.gnu.org/thanks.html}}, for contributors to GCC and G77@.
+See the Info entry for @command{g77} for contributors to GCC and G77@.
@c man end
@end ignore
The @command{g77} command supports all the options supported by the
@command{gcc} command.
-@xref{Invoking GCC,,GNU CC Command Options,gcc,Using and Porting GNU CC},
-for information
+@xref{Invoking GCC,,GCC Command Options,gcc,Using the GNU Compiler
+Collection (GCC)}, for information
on the non-Fortran-specific aspects of the @command{gcc} command (and,
therefore, the @command{g77} command).
@item Fortran Language Options
@xref{Fortran Dialect Options,,Options Controlling Fortran Dialect}.
@gccoptlist{
--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
+-ffree-form -fno-fixed-form -ff90 @gol
+-fvxt -fdollar-ok -fno-backslash @gol
+-fno-ugly-args -fno-ugly-assign -fno-ugly-assumed @gol
+-fugly-comma -fugly-complex -fugly-init -fugly-logint @gol
+-fonetrip -ftypeless-boz @gol
+-fintrin-case-initcap -fintrin-case-upper @gol
+-fintrin-case-lower -fintrin-case-any @gol
+-fmatch-case-initcap -fmatch-case-upper @gol
+-fmatch-case-lower -fmatch-case-any @gol
+-fsource-case-upper -fsource-case-lower @gol
+-fsource-case-preserve @gol
+-fsymbol-case-initcap -fsymbol-case-upper @gol
+-fsymbol-case-lower -fsymbol-case-any @gol
+-fcase-strict-upper -fcase-strict-lower @gol
+-fcase-initcap -fcase-upper -fcase-lower -fcase-preserve @gol
+-ff2c-intrinsics-delete -ff2c-intrinsics-hide @gol
+-ff2c-intrinsics-disable -ff2c-intrinsics-enable @gol
+-fbadu77-intrinsics-delete -fbadu77-intrinsics-hide @gol
+-fbadu77-intrinsics-disable -fbadu77-intrinsics-enable @gol
+-ff90-intrinsics-delete -ff90-intrinsics-hide @gol
+-ff90-intrinsics-disable -ff90-intrinsics-enable @gol
+-fgnu-intrinsics-delete -fgnu-intrinsics-hide @gol
+-fgnu-intrinsics-disable -fgnu-intrinsics-enable @gol
+-fmil-intrinsics-delete -fmil-intrinsics-hide @gol
+-fmil-intrinsics-disable -fmil-intrinsics-enable @gol
+-funix-intrinsics-delete -funix-intrinsics-hide @gol
+-funix-intrinsics-disable -funix-intrinsics-enable @gol
+-fvxt-intrinsics-delete -fvxt-intrinsics-hide @gol
+-fvxt-intrinsics-disable -fvxt-intrinsics-enable @gol
-ffixed-line-length-@var{n} -ffixed-line-length-none}
@item Warning Options
@xref{Warning Options,,Options to Request or Suppress Warnings}.
@gccoptlist{
--fsyntax-only -pedantic -pedantic-errors -fpedantic
--w -Wno-globals -Wimplicit -Wunused -Wuninitialized
--Wall -Wsurprising
+-fsyntax-only -pedantic -pedantic-errors -fpedantic @gol
+-w -Wno-globals -Wimplicit -Wunused -Wuninitialized @gol
+-Wall -Wsurprising @gol
-Werror -W}
@item Debugging Options
@item Optimization Options
@xref{Optimize Options,,Options that Control Optimization}.
@gccoptlist{
--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
+-malign-double @gol
+-ffloat-store -fforce-mem -fforce-addr -fno-inline @gol
+-ffast-math -fstrength-reduce -frerun-cse-after-loop @gol
+-funsafe-math-optimizations -ffinite-math-only -fno-trapping-math @gol
+-fexpensive-optimizations -fdelayed-branch @gol
+-fschedule-insns -fschedule-insn2 -fcaller-saves @gol
+-funroll-loops -funroll-all-loops @gol
+-fno-move-all-movables -fno-reduce-all-givs @gol
-fno-rerun-loop-opt}
@item Directory Options
@item Code Generation Options
@xref{Code Gen Options,,Options for Code Generation Conventions}.
@gccoptlist{
--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
+-fno-automatic -finit-local-zero -fno-f2c @gol
+-ff2c-library -fno-underscoring -fno-ident @gol
+-fpcc-struct-return -freg-struct-return @gol
+-fshort-double -fno-common -fpack-struct @gol
+-fzeros -fno-second-underscore @gol
+-femulate-complex @gol
+-falias-check -fargument-alias @gol
+-fargument-noalias -fno-argument-noalias-global @gol
+-fno-globals -fflatten-arrays @gol
-fbounds-check -ffortran-bounds-check}
@end table
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 GNU Fortran are listed below.
-@xref{Overall Options,,gcc,Using and Porting GNU CC}, for
-information on suffixes recognized by GNU CC.
+@xref{Overall Options,,Options Controlling the Kind of
+Output,gcc,Using the GNU Compiler Collection (GCC)}, for
+information on suffixes recognized by GCC.
@table @gcctabopt
@cindex .f filename suffix
@item @var{file}.fpp
@item @var{file}.FPP
Fortran source code that must be preprocessed (by the C preprocessor
-@command{cpp}, which is part of GNU CC).
+@command{cpp}, which is part of GCC).
Note that preprocessing is not extended to the contents of
files included by the @code{INCLUDE} directive---the @code{#include}
Ratfor source code, which must be preprocessed by the @command{ratfor}
command, which is available separately (as it is not yet part of the GNU
Fortran distribution).
-One version in Fortran, adapted for use with @command{g77} is at
-@uref{ftp://members.aol.com/n8tm/rat7.uue} (of uncertain copyright
-status). Another, public domain version in C is at
+A public domain version in C is at
@uref{http://sepwww.stanford.edu/sep/prof/ratfor.shar.2}.
@end table
@emph{Note:} The @option{-traditional} and @option{-undef} flags are supplied
to @command{cpp} by default, to help avoid unpleasant surprises.
@xref{Preprocessor Options,,Options Controlling the Preprocessor,
-gcc,Using and Porting GNU CC}.
+gcc,Using the GNU Compiler Collection (GCC)}.
This means that ANSI C preprocessor features (such as the @samp{#}
operator) aren't available, and only variables in the C reserved
namespace (generally, names with a leading underscore) are liable to
is specified as a command-line option for @command{g77} or @command{gcc}
and when the resulting commands compile Fortran source files.
-In GCC 3.1, this is changed back to the behaviour @command{gcc} displays
+In GCC 3.1, this is changed back to the behavior @command{gcc} displays
for @samp{.c} files.
@cindex -fset-g77-defaults option
@end table
@xref{Overall Options,,Options Controlling the Kind of Output,
-gcc,Using and Porting GNU CC}, for information
+gcc,Using the GNU Compiler Collection (GCC)}, for information
on more options that control the overall operation of the @command{gcc} command
(and, by extension, the @command{g77} command).
@end table
@xref{Warning Options,,Options to Request or Suppress Warnings,
-gcc,Using and Porting GNU CC}, for information on more options offered
+gcc,Using the GNU Compiler Collection (GCC)}, for information on more
+options offered
by the GBE shared by @command{g77} @command{gcc} and other GNU compilers.
Some of these have no effect when compiling programs written in Fortran:
@cindex -Wswitch option
@cindex options, -Wswitch
@item -Wswitch
+@cindex -Wswitch-default option
+@cindex options, -Wswitch-default
+@item -Wswitch-default
+@cindex -Wswitch-enum option
+@cindex options, -Wswitch-enum
+@item -Wswitch-enum
@cindex -Wtraditional option
@cindex options, -Wtraditional
@item -Wtraditional
Produce debugging information in the operating system's native format
(stabs, COFF, XCOFF, or DWARF). GDB can work with this debugging
information.
+
+A sample debugging session looks like this (note the use of the breakpoint):
+@smallexample
+$ 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
+...
+@end smallexample
+One could also add the setting of the breakpoint and the first run command
+to the file @file{.gdbinit} in the current directory, to simplify the debugging
+session.
@end table
-@xref{Debugging Options,,Options for Debugging Your Program or GNU CC,
-gcc,Using and Porting GNU CC}, for more information on debugging options.
+@xref{Debugging Options,,Options for Debugging Your Program or GCC,
+gcc,Using the GNU Compiler Collection (GCC)}, for more information on
+debugging options.
@node Optimize Options
@section Options That Control Optimization
@cindex conformance, IEEE 754
Might allow some programs designed to not be too dependent
on IEEE behavior for floating-point to run faster, or die trying.
-Sets @option{-funsafe-math-optimizations}, and
-@option{-fno-trapping-math}.
+Sets @option{-funsafe-math-optimizations}, @option{-ffinite-math-only},
+and @option{-fno-trapping-math}.
@cindex -funsafe-math-optimizations option
@cindex options, -funsafe-math-optimizations
Allow optimizations that may be give incorrect results
for certain IEEE inputs.
+@cindex -ffinite-math-only option
+@cindex options, -ffinite-math-only
+@item -ffinite-math-only
+Allow optimizations for floating-point arithmetic that assume
+that arguments and results are not NaNs or +-Infs.
+
+This option should never be turned on by any @option{-O} option since
+it can result in incorrect output for programs which depend on
+an exact implementation of IEEE or ISO rules/specifications.
+
+The default is @option{-fno-finite-math-only}.
+
@cindex -fno-trapping-math option
@cindex options, -fno-trapping-math
@item -fno-trapping-math
@item -fno-rerun-loop-opt
@cindex -fno-rerun-loop-opt option
@cindex options, -fno-rerun-loop-opt
-@emph{Version info:}
-These options are not supported by
-versions of @command{g77} based on @command{gcc} version 2.8.
+In general, the optimizations enabled with these options will lead to
+faster code being generated by GNU Fortran; hence they are enabled by default
+when issuing the @command{g77} command.
-Each of these might improve performance on some code.
+@option{-fmove-all-movables} and @option{-freduce-all-givs} will enable
+loop optimization to move all loop-invariant index computations in nested
+loops over multi-rank array dummy arguments out of these loops.
-Analysis of Fortran code optimization and the resulting
-optimizations triggered by the above options were
-contributed by Toon Moene (@email{toon@@moene.indiv.nluug.nl}).
+@option{-frerun-loop-opt} will move offset calculations resulting
+from the fact that Fortran arrays by default have a lower bound of 1
+out of the loops.
These three options are intended to be removed someday, once
-they have helped determine the efficacy of various
-approaches to improving the performance of Fortran code.
-
-Please let us know how use of these options affects
-the performance of your production code.
-We're particularly interested in code that runs faster
-when these options are @emph{disabled}, and in
-non-Fortran code that benefits when they are
-@emph{enabled} via the above @command{gcc} command-line options.
+loop optimization is sufficiently advanced to perform all those
+transformations without help from these options.
@end table
@xref{Optimize Options,,Options That Control Optimization,
-gcc,Using and Porting GNU CC}, for more information on options
+gcc,Using the GNU Compiler Collection (GCC)}, for more information on options
to optimize the generated machine code.
@node Preprocessor Options
file before actual compilation.
@xref{Preprocessor Options,,Options Controlling the Preprocessor,
-gcc,Using and Porting GNU CC}, for information on C preprocessor options.
+gcc,Using the GNU Compiler Collection (GCC)}, for information on C
+preprocessor options.
@cindex INCLUDE directive
@cindex directive, INCLUDE
looking for @file{header.gcc} files and other such things.
@xref{Directory Options,,Options for Directory Search,
-gcc,Using and Porting GNU CC}, for information on the @option{-I} option.
+gcc,Using the GNU Compiler Collection (GCC)}, for information on the
+@option{-I} option.
@end table
@node Code Gen Options
@end table
@xref{Code Gen Options,,Options for Code Generation Conventions,
-gcc,Using and Porting GNU CC}, for information on more options
+gcc,Using the GNU Compiler Collection (GCC)}, for information on more options
offered by the GBE
shared by @command{g77} @command{gcc} and other GNU compilers.
variables to control its operation above and beyond those
that affect the operation of @command{gcc}.
-@xref{Environment Variables,,Environment Variables Affecting GNU CC,
-gcc,Using and Porting GNU CC}, for information on environment
+@xref{Environment Variables,,Environment Variables Affecting GCC,
+gcc,Using the GNU Compiler Collection (GCC)}, for information on environment
variables.
@c man end
projects / thirdparty / gcc.git / blobdiff