@c man begin COPYRIGHT
Copyright @copyright{} 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
+1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
+2007 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 1.2 or
@c man end
@c man begin BUGS
For instructions on reporting bugs, see
-@w{@uref{http://gcc.gnu.org/bugs.html}}.
+@w{@value{BUGURL}}.
@c man end
@c man begin AUTHOR
See the Info entry for @command{gcc}, or
-Werror -Werror=* @gol
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-extra-args -Wformat-nonliteral @gol
--Wformat-security -Wformat-y2k @gol
+-Wformat-security -Wformat-y2k -Wignored-qualifiers @gol
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int @gol
-Wimport -Wno-import -Winit-self -Winline @gol
-Wno-int-to-pointer-cast -Wno-invalid-offsetof @gol
-ftest-coverage -ftime-report -fvar-tracking @gol
-g -g@var{level} -gcoff -gdwarf-2 @gol
-ggdb -gstabs -gstabs+ -gvms -gxcoff -gxcoff+ @gol
+-fdebug-prefix-map=@var{old}=@var{new} @gol
-femit-struct-debug-baseonly -femit-struct-debug-reduced @gol
-femit-struct-debug-detailed@r{[}=@var{spec-list}@r{]} @gol
-p -pg -print-file-name=@var{library} -print-libgcc-file-name @gol
@item Optimization Options
@xref{Optimize Options,,Options that Control Optimization}.
-@gccoptlist{-falign-functions=@var{n} -falign-jumps=@var{n} @gol
--falign-labels=@var{n} -falign-loops=@var{n} @gol
--fbounds-check -fmudflap -fmudflapth -fmudflapir @gol
--fbranch-probabilities -fprofile-values -fvpt -fbranch-target-load-optimize @gol
--fbranch-target-load-optimize2 -fbtr-bb-exclusive @gol
--fcaller-saves -fcprop-registers -fcse-follow-jumps @gol
--fcse-skip-blocks -fcx-limited-range -fdata-sections @gol
--fdelayed-branch -fdelete-null-pointer-checks -fearly-inlining @gol
--fexpensive-optimizations -ffast-math -ffloat-store @gol
--fforce-addr -fforward-propagate -ffunction-sections @gol
--fgcse -fgcse-lm -fgcse-sm -fgcse-las -fgcse-after-reload @gol
--fcrossjumping -fif-conversion -fif-conversion2 @gol
--finline-functions -finline-functions-called-once @gol
--finline-limit=@var{n} -fkeep-inline-functions @gol
--fkeep-static-consts -fmerge-constants -fmerge-all-constants @gol
--fmodulo-sched -fno-branch-count-reg @gol
--fno-default-inline -fno-defer-pop -fmove-loop-invariants @gol
--fno-function-cse -fno-guess-branch-probability @gol
--fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
--funsafe-math-optimizations -funsafe-loop-optimizations @gol
--ffinite-math-only -fno-signed-zeros @gol
--fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss @gol
--fomit-frame-pointer -foptimize-register-move @gol
--foptimize-sibling-calls -fpredictive-commoning -fprefetch-loop-arrays @gol
--fprofile-generate -fprofile-use @gol
--fregmove -frename-registers @gol
--freorder-blocks -freorder-blocks-and-partition -freorder-functions @gol
--frerun-cse-after-loop @gol
--frounding-math -frtl-abstract-sequences @gol
--fschedule-insns -fschedule-insns2 @gol
--fno-sched-interblock -fno-sched-spec -fsched-spec-load @gol
--fsched-spec-load-dangerous @gol
--fsched-stalled-insns=@var{n} -fsched-stalled-insns-dep=@var{n} @gol
--fsched2-use-superblocks @gol
--fsched2-use-traces -fsee -freschedule-modulo-scheduled-loops @gol
--fsection-anchors -fsignaling-nans -fsingle-precision-constant @gol
--fno-split-wide-types -fstack-protector -fstack-protector-all @gol
--fstrict-aliasing -fstrict-overflow -ftracer -fthread-jumps @gol
--funroll-all-loops -funroll-loops -fpeel-loops @gol
--fsplit-ivs-in-unroller -funswitch-loops @gol
--fvariable-expansion-in-unroller @gol
--ftree-pre -ftree-ccp -ftree-dce -ftree-loop-optimize @gol
--ftree-loop-linear -ftree-loop-im -ftree-loop-ivcanon -fivopts @gol
--fcheck-data-deps @gol
--ftree-dominator-opts -ftree-dse -ftree-copyrename -ftree-sink @gol
--ftree-ch -ftree-sra -ftree-ter -ftree-fre -ftree-vectorize @gol
--ftree-vect-loop-version -fvect-cost-model -ftree-salias -fipa-pta -fweb @gol
--ftree-copy-prop -ftree-store-ccp -ftree-store-copy-prop -fwhole-program @gol
+@gccoptlist{
+-falign-functions[=@var{n}] -falign-jumps[=@var{n}] @gol
+-falign-labels[=@var{n}] -falign-loops[=@var{n}] -fassociative-math @gol
+-fauto-inc-dec -fbranch-probabilities -fbranch-target-load-optimize @gol
+-fbranch-target-load-optimize2 -fbtr-bb-exclusive -fcaller-saves @gol
+-fcheck-data-deps -fcprop-registers -fcrossjumping -fcse-follow-jumps @gol
+-fcse-skip-blocks -fcx-limited-range -fdata-sections -fdce -fdce @gol
+-fdelayed-branch -fdelete-null-pointer-checks -fdse -fdse @gol
+-fearly-inlining -fexpensive-optimizations -ffast-math @gol
+-ffinite-math-only -ffloat-store -fforward-propagate @gol
+-ffunction-sections -fgcse -fgcse-after-reload -fgcse-las -fgcse-lm @gol
+-fgcse-sm -fif-conversion -fif-conversion2 -finline-functions @gol
+-finline-functions-called-once -finline-limit=@var{n} @gol
+-finline-small-functions -fipa-cp -fipa-marix-reorg -fipa-pta @gol
+-fipa-pure-const -fipa-reference -fipa-struct-reorg @gol
+-fipa-type-escape -fivopts -fkeep-inline-functions -fkeep-static-consts @gol
+-fmerge-all-constants -fmerge-constants -fmodulo-sched @gol
+-fmodulo-sched-allow-regmoves -fmove-loop-invariants -fmudflap @gol
+-fmudflapir -fmudflapth -fno-branch-count-reg -fno-default-inline @gol
+-fno-defer-pop -fno-function-cse -fno-guess-branch-probability @gol
+-fno-inline -fno-math-errno -fno-peephole -fno-peephole2 @gol
+-fno-sched-interblock -fno-sched-spec -fno-signed-zeros @gol
+-fno-toplevel-reorder -fno-trapping-math -fno-zero-initialized-in-bss @gol
+-fomit-frame-pointer -foptimize-register-move -foptimize-sibling-calls @gol
+-fpeel-loops -fpredictive-commoning -fprefetch-loop-arrays @gol
+-fprofile-generate -fprofile-use -fprofile-values -freciprocal-math @gol
+-fregmove -frename-registers -freorder-blocks @gol
+-freorder-blocks-and-partition -freorder-functions @gol
+-frerun-cse-after-loop -freschedule-modulo-scheduled-loops @gol
+-frounding-math -frtl-abstract-sequences -fsched2-use-superblocks @gol
+-fsched2-use-traces -fsched-spec-load -fsched-spec-load-dangerous @gol
+-fsched-stalled-insns-dep[=@var{n}] -fsched-stalled-insns[=@var{n}] @gol
+-fschedule-insns -fschedule-insns2 -fsection-anchors -fsee @gol
+-fsignaling-nans -fsingle-precision-constant -fsplit-ivs-in-unroller @gol
+-fsplit-wide-types -fstack-protector -fstack-protector-all @gol
+-fstrict-aliasing -fstrict-overflow -fthread-jumps -ftracer -ftree-ccp @gol
+-ftree-ch -ftree-copy-prop -ftree-copyrename -ftree-dce @gol
+-ftree-dominator-opts -ftree-dse -ftree-fre -ftree-loop-im @gol
+-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
+-ftree-parallelize-loops=@var{n} -ftree-pre -ftree-reassoc -ftree-salias @gol
+-ftree-sink -ftree-sra -ftree-store-ccp -ftree-ter @gol
+-ftree-vect-loop-version -ftree-vectorize -ftree-vrp -funit-at-a-time @gol
+-funroll-all-loops -funroll-loops -funsafe-loop-optimizations @gol
+-funsafe-math-optimizations -funswitch-loops @gol
+-fvariable-expansion-in-unroller -fvect-cost-model -fvpt -fweb @gol
+-fwhole-program @gol
--param @var{name}=@var{value}
-O -O0 -O1 -O2 -O3 -Os}
-mcall-prologues -mno-tablejump -mtiny-stack -mint8}
@emph{Blackfin Options}
-@gccoptlist{-mcpu=@var{cpu} -msim -momit-leaf-frame-pointer @gol
--mno-omit-leaf-frame-pointer -mspecld-anomaly -mno-specld-anomaly @gol
--mcsync-anomaly -mno-csync-anomaly -mlow-64k -mno-low64k @gol
--mstack-check-l1 -mid-shared-library -mno-id-shared-library @gol
--mshared-library-id=@var{n} -mleaf-id-shared-library @gol
--mno-leaf-id-shared-library -msep-data -mno-sep-data -mlong-calls @gol
--mno-long-calls}
+@gccoptlist{-mcpu=@var{cpu}@r{[}-@var{sirevision}@r{]} @gol
+-msim -momit-leaf-frame-pointer -mno-omit-leaf-frame-pointer @gol
+-mspecld-anomaly -mno-specld-anomaly -mcsync-anomaly -mno-csync-anomaly @gol
+-mlow-64k -mno-low64k -mstack-check-l1 -mid-shared-library @gol
+-mno-id-shared-library -mshared-library-id=@var{n} @gol
+-mleaf-id-shared-library -mno-leaf-id-shared-library @gol
+-msep-data -mno-sep-data -mlong-calls -mno-long-calls @gol
+-mfast-fp -minline-plt}
@emph{CRIS Options}
@gccoptlist{-mcpu=@var{cpu} -march=@var{cpu} -mtune=@var{cpu} @gol
-mno-wide-multiply -mrtd -malign-double @gol
-mpreferred-stack-boundary=@var{num} -mcx16 -msahf -mrecip @gol
-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 @gol
--msse4a -m3dnow -mpopcnt -mabm @gol
+-msse4a -m3dnow -mpopcnt -mabm -msse5 @gol
-mthreads -mno-align-stringops -minline-all-stringops @gol
-mpush-args -maccumulate-outgoing-args -m128bit-long-double @gol
-m96bit-long-double -mregparm=@var{num} -msseregparm @gol
--mpc32 -mpc64 -mpc80 mstackrealign @gol
+-mveclibabi=@var{type} -mpc32 -mpc64 -mpc80 -mstackrealign @gol
-momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs @gol
-mcmodel=@var{code-model} @gol
--m32 -m64 -mlarge-data-threshold=@var{num}}
+-m32 -m64 -mlarge-data-threshold=@var{num} @gol
+-mfused-madd -mno-fused-madd}
@emph{IA-64 Options}
@gccoptlist{-mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic @gol
@emph{MIPS Options}
@gccoptlist{-EL -EB -march=@var{arch} -mtune=@var{arch} @gol
-mips1 -mips2 -mips3 -mips4 -mips32 -mips32r2 -mips64 @gol
--mips16 -mno-mips16 -mabi=@var{abi} -mabicalls -mno-abicalls @gol
+-mips16 -mno-mips16 -mflip-mips16 @gol
+-minterlink-mips16 -mno-interlink-mips16 @gol
+-mabi=@var{abi} -mabicalls -mno-abicalls @gol
-mshared -mno-shared -mxgot -mno-xgot -mgp32 -mgp64 @gol
-mfp32 -mfp64 -mhard-float -msoft-float @gol
-msingle-float -mdouble-float -mdsp -mno-dsp -mdspr2 -mno-dspr2 @gol
+-msmartmips -mno-smartmips @gol
-mpaired-single -mno-paired-single -mdmx -mno-mdmx @gol
--mips3d -mno-mips3d -mmt -mno-mt @gol
+-mips3d -mno-mips3d -mmt -mno-mt -mllsc -mno-llsc @gol
-mlong64 -mlong32 -msym32 -mno-sym32 @gol
--G@var{num} -membedded-data -mno-embedded-data @gol
+-G@var{num} -mlocal-sdata -mno-local-sdata @gol
+-mextern-sdata -mno-extern-sdata -mgpopt -mno-gopt @gol
+-membedded-data -mno-embedded-data @gol
-muninit-const-in-rodata -mno-uninit-const-in-rodata @gol
+-mcode-readable=@var{setting} @gol
-msplit-addresses -mno-split-addresses @gol
-mexplicit-relocs -mno-explicit-relocs @gol
-mcheck-zero-division -mno-check-zero-division @gol
-mfix-vr4120 -mno-fix-vr4120 -mfix-vr4130 -mno-fix-vr4130 @gol
-mfix-sb1 -mno-fix-sb1 @gol
-mflush-func=@var{func} -mno-flush-func @gol
--mbranch-likely -mno-branch-likely @gol
+-mbranch-cost=@var{num} -mbranch-likely -mno-branch-likely @gol
-mfp-exceptions -mno-fp-exceptions @gol
-mvr4130-align -mno-vr4130-align}
-mpowerpc-gpopt -mno-powerpc-gpopt @gol
-mpowerpc-gfxopt -mno-powerpc-gfxopt @gol
-mmfcrf -mno-mfcrf -mpopcntb -mno-popcntb -mfprnd -mno-fprnd @gol
--mcmpb -mno-cmpb -mmfpgpr -mno-mfpgpr -mdfp -mno-dfp @gol
+-mcmpb -mno-cmpb -mmfpgpr -mno-mfpgpr -mhard-dfp -mno-hard-dfp @gol
-mnew-mnemonics -mold-mnemonics @gol
-mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc @gol
-m64 -m32 -mxl-compat -mno-xl-compat -mpe @gol
-misel=yes -misel=no @gol
-mspe -mno-spe @gol
-mspe=yes -mspe=no @gol
+-mpaired @gol
-mvrsave -mno-vrsave @gol
-mmulhw -mno-mulhw @gol
-mdlmzb -mno-dlmzb @gol
-fnon-call-exceptions -funwind-tables @gol
-fasynchronous-unwind-tables @gol
-finhibit-size-directive -finstrument-functions @gol
+-finstrument-functions-exclude-function-list=@var{sym},@var{sym},@dots{} @gol
+-finstrument-functions-exclude-file-list=@var{file},@var{file},@dots{} @gol
-fno-common -fno-ident @gol
-fpcc-struct-return -fpic -fPIC -fpie -fPIE @gol
-fno-jump-tables @gol
-fshort-double -fshort-wchar @gol
-fverbose-asm -fpack-struct[=@var{n}] -fstack-check @gol
-fstack-limit-register=@var{reg} -fstack-limit-symbol=@var{sym} @gol
--fargument-alias -fargument-noalias @gol
--fargument-noalias-global -fargument-noalias-anything
+-fno-stack-limit -fargument-alias -fargument-noalias @gol
+-fargument-noalias-global -fargument-noalias-anything @gol
-fleading-underscore -ftls-model=@var{model} @gol
-ftrapv -fwrapv -fbounds-check @gol
-fvisibility}
@item @var{file}.hh
@itemx @var{file}.H
+@itemx @var{file}.hp
+@itemx @var{file}.hxx
+@itemx @var{file}.hpp
+@itemx @var{file}.HPP
+@itemx @var{file}.h++
+@itemx @var{file}.tcc
C++ header file to be turned into a precompiled header.
@item @var{file}.f
Assembler code.
@item @var{file}.S
+@itemx @var{file}.sx
Assembler code which must be preprocessed.
@item @var{other}
@item --target-help
@opindex target-help
Print (on the standard output) a description of target-specific command
-line options for each tool.
+line options for each tool. For some targets extra target-specific
+information may also be printed.
@item --help=@var{class}@r{[},@var{qualifier}@r{]}
Print (on the standard output) a description of the command line
@cindex C++ source file suffixes
C++ source files conventionally use one of the suffixes @samp{.C},
@samp{.cc}, @samp{.cpp}, @samp{.CPP}, @samp{.c++}, @samp{.cp}, or
-@samp{.cxx}; C++ header files often use @samp{.hh} or @samp{.H}; and
+@samp{.cxx}; C++ header files often use @samp{.hh}, @samp{.hpp},
+@samp{.H}, or (for shared template code) @samp{.tcc}; and
preprocessed C++ files use the suffix @samp{.ii}. GCC recognizes
files with these names and compiles them as C++ programs even if you
call the compiler the same way as for compiling C programs (usually
Enable handling of OpenMP directives @code{#pragma omp} in C/C++ and
@code{!$omp} in Fortran. When @option{-fopenmp} is specified, the
compiler generates parallel code according to the OpenMP Application
-Program Interface v2.5 @w{@uref{http://www.openmp.org/}}.
+Program Interface v2.5 @w{@uref{http://www.openmp.org/}}. This option
+implies @option{-pthread}, and thus is only supported on targets that
+have support for @option{-pthread}.
@item -fms-extensions
@opindex fms-extensions
In new code it is better to use @option{-fvisibility=hidden} and
export those classes which are intended to be externally visible.
Unfortunately it is possible for code to rely, perhaps accidentally,
-on the Visual Studio behaviour.
+on the Visual Studio behavior.
Among the consequences of these changes are that static data members
of the same type with the same name but defined in different shared
@item -Wnon-virtual-dtor @r{(C++ only)}
@opindex Wnon-virtual-dtor
-Warn when a class appears to be polymorphic, thereby requiring a virtual
-destructor, yet it declares a non-virtual one. This warning is also
-enabled if -Weffc++ is specified.
+Warn when a class has virtual functions and accessible non-virtual
+destructor, in which case it would be possible but unsafe to delete
+an instance of a derived class through a pointer to the base class.
+This warning is also enabled if -Weffc++ is specified.
@item -Wreorder @r{(C++ only)}
@opindex Wreorder
are not inherently erroneous but which are risky or suggest there
may have been an error.
-You can request many specific warnings with options beginning @samp{-W},
-for example @option{-Wimplicit} to request warnings on implicit
-declarations. Each of these specific warning options also has a
-negative form beginning @samp{-Wno-} to turn off warnings;
-for example, @option{-Wno-implicit}. This manual lists only one of the
-two forms, whichever is not the default.
-
-The following options control the amount and kinds of warnings produced
-by GCC; for further, language-specific options also refer to
-@ref{C++ Dialect Options} and @ref{Objective-C and Objective-C++ Dialect
-Options}.
+The following language-independent options do not enable specific
+warnings but control the kinds of diagnostics produced by GCC.
@table @gcctabopt
@cindex syntax checking
@opindex fsyntax-only
Check the code for syntax errors, but don't do anything beyond that.
+@item -w
+@opindex w
+Inhibit all warning messages.
+
+@item -Werror
+@opindex Werror
+Make all warnings into errors.
+
+@item -Werror=
+@opindex Werror=
+Make the specified warning into an error. The specifier for a warning
+is appended, for example @option{-Werror=switch} turns the warnings
+controlled by @option{-Wswitch} into errors. This switch takes a
+negative form, to be used to negate @option{-Werror} for specific
+warnings, for example @option{-Wno-error=switch} makes
+@option{-Wswitch} warnings not be errors, even when @option{-Werror}
+is in effect. You can use the @option{-fdiagnostics-show-option}
+option to have each controllable warning amended with the option which
+controls it, to determine what to use with this option.
+
+Note that specifying @option{-Werror=}@var{foo} automatically implies
+@option{-W}@var{foo}. However, @option{-Wno-error=}@var{foo} does not
+imply anything.
+
+@item -Wfatal-errors
+@opindex Wfatal-errors
+This option causes the compiler to abort compilation on the first error
+occurred rather than trying to keep going and printing further error
+messages.
+
+@end table
+
+You can request many specific warnings with options beginning
+@samp{-W}, for example @option{-Wimplicit} to request warnings on
+implicit declarations. Each of these specific warning options also
+has a negative form beginning @samp{-Wno-} to turn off warnings; for
+example, @option{-Wno-implicit}. This manual lists only one of the
+two forms, whichever is not the default. For further,
+language-specific options also refer to @ref{C++ Dialect Options} and
+@ref{Objective-C and Objective-C++ Dialect Options}.
+
+@table @gcctabopt
@item -pedantic
@opindex pedantic
Issue all the warnings demanded by strict ISO C and ISO C++;
Like @option{-pedantic}, except that errors are produced rather than
warnings.
-@item -w
-@opindex w
-Inhibit all warning messages.
+@item -Wall
+@opindex Wall
+This enables all the warnings about constructions that some users
+consider questionable, and that are easy to avoid (or modify to
+prevent the warning), even in conjunction with macros. This also
+enables some language-specific warnings described in @ref{C++ Dialect
+Options} and @ref{Objective-C and Objective-C++ Dialect Options}.
+
+@option{-Wall} turns on the following warning flags:
+
+@gccoptlist{-Waddress @gol
+-Warray-bounds @r{(only with} @option{-O2}@r{)} @gol
+-Wc++0x-compat @gol
+-Wchar-subscripts @gol
+-Wimplicit-int @gol
+-Wimplicit-function-declaration @gol
+-Wcomment @gol
+-Wformat @gol
+-Wmain @r{(only for C/ObjC and unless} @option{-ffreestanding}@r{)} @gol
+-Wmissing-braces @gol
+-Wnonnull @gol
+-Wparentheses @gol
+-Wpointer-sign @gol
+-Wreorder @gol
+-Wreturn-type @gol
+-Wsequence-point @gol
+-Wsign-compare @r{(only in C++)} @gol
+-Wstrict-aliasing @gol
+-Wstrict-overflow @gol
+-Wswitch @gol
+-Wtrigraphs @gol
+-Wuninitialized @r{(only with} @option{-O1} @r{and above)} @gol
+-Wunknown-pragmas @gol
+-Wunused-function @gol
+-Wunused-label @gol
+-Wunused-value @gol
+-Wunused-variable @gol
+}
+
+Note that some warning flags are not implied by @option{-Wall}. Some of
+them warn about constructions that users generally do not consider
+questionable, but which occasionally you might wish to check for;
+others warn about constructions that are necessary or hard to avoid in
+some cases, and there is no simple way to modify the code to suppress
+the warning. Some of them are enabled by @option{-Wextra} but many of
+them must be enabled individually.
+
+@item -Wextra
+@opindex W
+@opindex Wextra
+This enables some extra warning flags that are not enabled by
+@option{-Wall}. (This option used to be called @option{-W}. The older
+name is still supported, but the newer name is more descriptive.)
+
+@gccoptlist{-Wclobbered @gol
+-Wempty-body @gol
+-Wignored-qualifiers @gol
+-Wmissing-field-initializers @gol
+-Wmissing-parameter-type @r{(C only)} @gol
+-Wold-style-declaration @r{(C only)} @gol
+-Woverride-init @gol
+-Wsign-compare @gol
+-Wtype-limits @gol
+-Wuninitialized @r{(only with} @option{-O1} @r{and above)} @gol
+-Wunused-parameter @r{(only with} @option{-Wunused} @r{or} @option{-Wall}@r{)} @gol
+}
+
+The option @option{-Wextra} also prints warning messages for the
+following cases:
+
+@itemize @bullet
+
+@item
+A pointer is compared against integer zero with @samp{<}, @samp{<=},
+@samp{>}, or @samp{>=}.
+
+@item
+(C++ only) An enumerator and a non-enumerator both appear in a
+conditional expression.
+
+@item
+(C++ only) A non-static reference or non-static @samp{const} member
+appears in a class without constructors.
+
+@item
+(C++ only) Ambiguous virtual bases.
+
+@item
+(C++ only) Subscripting an array which has been declared @samp{register}.
+
+@item
+(C++ only) Taking the address of a variable which has been declared
+@samp{register}.
+
+@item
+(C++ only) A base class is not initialized in a derived class' copy
+constructor.
+
+@end itemize
@item -Wno-import
@opindex Wno-import
comment, or whenever a Backslash-Newline appears in a @samp{//} comment.
This warning is enabled by @option{-Wall}.
-@item -Wfatal-errors
-@opindex Wfatal-errors
-This option causes the compiler to abort compilation on the first error
-occurred rather than trying to keep going and printing further error
-messages.
-
@item -Wformat
@opindex Wformat
@opindex ffreestanding
Same as @option{-Wimplicit-int} and @option{-Wimplicit-function-declaration}.
This warning is enabled by @option{-Wall}.
+@item -Wignored-qualifiers
+@opindex Wignored-qualifiers
+@opindex Wno-ignored-qualifiers
+Warn if the return type of a function has a type qualifier
+such as @code{const}. For ISO C such a type qualifier has no effect,
+since the value returned by a function is not an lvalue.
+For C++, the warning is only emitted for scalar types or @code{void}.
+ISO C prohibits qualified @code{void} return types on function
+definitions, so such return types always receive a warning
+even without this option.
+
+This warning is also enabled by @option{-Wextra}.
+
@item -Wmain
@opindex Wmain
Warn if the type of @samp{main} is suspicious. @samp{main} should be a
without a value), and about a @code{return} statement with a
expression in a function whose return-type is @code{void}.
-Also warn if the return type of a function has a type qualifier
-such as @code{const}. For ISO C such a type qualifier has no effect,
-since the value returned by a function is not an lvalue.
-For C++, the warning is only emitted for scalar types or @code{void}.
-ISO C prohibits qualified @code{void} return types on function
-definitions, so such return types always receive a warning
-even without this option.
-
For C++, a function without return type always produces a diagnostic
message, even when @option{-Wno-return-type} is specified. The only
exceptions are @samp{main} and functions defined in system headers.
you use that never return as @code{noreturn}. @xref{Function
Attributes}.
-This warning is enabled by @option{-Wall}.
+This warning is enabled by @option{-Wall} or @option{-Wextra} in
+optimizing compilations (@option{-O1} and above).
@item -Wunknown-pragmas
@opindex Wunknown-pragmas
compiler is using for optimization. The warning does not catch all
cases, but does attempt to catch the more common pitfalls. It is
included in @option{-Wall}.
-It is equivalent to -Wstrict-aliasing=3
+It is equivalent to @option{-Wstrict-aliasing=3}
@item -Wstrict-aliasing=n
@opindex Wstrict-aliasing=n
Does not warn about incomplete types.
@item -Wstrict-overflow
-@item -Wstrict-overflow=@var{n}
+@itemx -Wstrict-overflow=@var{n}
@opindex Wstrict-overflow
This option is only active when @option{-fstrict-overflow} is active.
It warns about cases where the compiler optimizes based on the
will require, in particular when determining whether a loop will be
executed at all.
-@table @option
+@table @gcctabopt
@item -Wstrict-overflow=1
Warn about cases which are both questionable and easy to avoid. For
example: @code{x + 1 > x}; with @option{-fstrict-overflow}, the
(default for -O2 and above). It warns about subscripts to arrays
that are always out of bounds. This warning is enabled by @option{-Wall}.
-@item -Wall
-@opindex Wall
-All of the above @samp{-W} options combined. This enables all the
-warnings about constructions that some users consider questionable, and
-that are easy to avoid (or modify to prevent the warning), even in
-conjunction with macros. This also enables some language-specific
-warnings described in @ref{C++ Dialect Options} and
-@ref{Objective-C and Objective-C++ Dialect Options}.
-@end table
-
-The following @option{-W@dots{}} options are not implied by @option{-Wall}.
-Some of them warn about constructions that users generally do not
-consider questionable, but which occasionally you might wish to check
-for; others warn about constructions that are necessary or hard to avoid
-in some cases, and there is no simple way to modify the code to suppress
-the warning.
-
-@table @gcctabopt
-@item -Wextra
-@opindex W
-@opindex Wextra
-(This option used to be called @option{-W}. The older name is still
-supported, but the newer name is more descriptive.) Print extra warning
-messages for these events:
-
-@itemize @bullet
-@item
-Warn if a comparison is always true or always false due to the limited
-range of the data type, but do not warn for constant expressions. For
-example, warn if an unsigned variable is compared against zero with
-@samp{<} or @samp{>=}. This warning can be independently controlled
-by @option{-Wtype-limits}.
-
-@item @r{(C only)}
-Storage-class specifiers like @code{static} are not the first things
-in a declaration. According to the C Standard, this usage is
-obsolescent. This warning can be independently controlled by
-@option{-Wold-style-declaration}.
-
-@item
-If @option{-Wall} or @option{-Wunused} is also specified, warn about unused
-arguments.
-
-@item
-A comparison between signed and unsigned values could produce an
-incorrect result when the signed value is converted to unsigned.
-(But don't warn if @option{-Wno-sign-compare} is also specified.)
-
-@item
-An aggregate has an initializer which does not initialize all members.
-This warning can be independently controlled by
-@option{-Wmissing-field-initializers}.
-
-@item
-An initialized field without side effects is overridden when using
-designated initializers (@pxref{Designated Inits, , Designated
-Initializers}). This warning can be independently controlled by
-@option{-Woverride-init}.
-
-@item @r{(C only)}
-A function parameter is declared without a type specifier in K&R-style
-functions. This warning can be independently controlled by
-@option{-Wmissing-parameter-type}.
-
-@item
-An empty body occurs in an @samp{if}, @samp{else} or
-@samp{do while} statement. This warning can be independently
-controlled by @option{-Wempty-body}.
-
-@item @r{(C++ only)}
-An empty body occurs in a @samp{while} or @samp{for} statement with no
-whitespacing before the semicolon. This warning can be independently
-controlled by @option{-Wempty-body}.
-
-@item
-A pointer is compared against integer zero with @samp{<}, @samp{<=},
-@samp{>}, or @samp{>=}.
-
-@item
-A variable might be changed by @samp{longjmp} or @samp{vfork}.
-This warning can be independently controlled by @option{-Wclobbered}.
-
-@item @r{(C++ only)}
-An enumerator and a non-enumerator both appear in a conditional expression.
-
-@item @r{(C++ only)}
-A non-static reference or non-static @samp{const} member appears in a
-class without constructors.
-
-@item @r{(C++ only)}
-Ambiguous virtual bases.
-
-@item @r{(C++ only)}
-Subscripting an array which has been declared @samp{register}.
-
-@item @r{(C++ only)}
-Taking the address of a variable which has been declared @samp{register}.
-
-@item @r{(C++ only)}
-A base class is not initialized in a derived class' copy constructor.
-@end itemize
-
@item -Wno-div-by-zero
@opindex Wno-div-by-zero
@opindex Wdiv-by-zero
@option{-Wall} and by @option{-pedantic}, which can be disabled with
@option{-Wno-pointer-sign}.
-@item -Werror
-@opindex Werror
-Make all warnings into errors.
-
-@item -Werror=
-@opindex Werror=
-Make the specified warning into an errors. The specifier for a
-warning is appended, for example @option{-Werror=switch} turns the
-warnings controlled by @option{-Wswitch} into errors. This switch
-takes a negative form, to be used to negate @option{-Werror} for
-specific warnings, for example @option{-Wno-error=switch} makes
-@option{-Wswitch} warnings not be errors, even when @option{-Werror}
-is in effect. You can use the @option{-fdiagnostics-show-option}
-option to have each controllable warning amended with the option which
-controls it, to determine what to use with this option.
-
-Note that specifying @option{-Werror=}@var{foo} automatically implies
-@option{-W}@var{foo}. However, @option{-Wno-error=}@var{foo} does not
-imply anything.
-
@item -Wstack-protector
@opindex Wstack-protector
This option is only active when @option{-fstack-protector} is active. It
This option works only with DWARF 2.
+@item -fdebug-prefix-map=@var{old}=@var{new}
+@opindex fdebug-prefix-map
+When compiling files in directory @file{@var{old}}, record debugging
+information describing them as in @file{@var{new}} instead.
+
@cindex @command{prof}
@item -p
@opindex p
compiler. The file names for most of the dumps are made by appending a
pass number and a word to the @var{dumpname}. @var{dumpname} is generated
from the name of the output file, if explicitly specified and it is not
-an executable, otherwise it is the basename of the source file.
+an executable, otherwise it is the basename of the source file. These
+switches may have different effects when @option{-E} is used for
+preprocessing.
Most debug dumps can be enabled either passing a letter to the @option{-d}
option, or with a long @option{-fdump-rtl} switch; here are the possible
@opindex dM
@opindex fdump-rtl-mach
Dump after performing the machine dependent reorganization pass, to
-@file{@var{file}.155r.mach}.
+@file{@var{file}.155r.mach} if that pass exists.
@item -dn
@itemx -fdump-rtl-rnreg
compilation time.
@option{-O} turns on the following optimization flags:
-@gccoptlist{-fdefer-pop @gol
+@gccoptlist{
+-fauto-inc-dec @gol
+-fcprop-registers @gol
+-fdce @gol
+-fdefer-pop @gol
-fdelayed-branch @gol
+-fdse @gol
-fguess-branch-probability @gol
--fcprop-registers @gol
--fif-conversion @gol
-fif-conversion2 @gol
+-fif-conversion @gol
+-finline-small-functions @gol
+-fipa-pure-const @gol
+-fipa-reference @gol
+-fmerge-constants
-fsplit-wide-types @gol
-ftree-ccp @gol
+-ftree-ch @gol
+-ftree-copyrename @gol
-ftree-dce @gol
-ftree-dominator-opts @gol
-ftree-dse @gol
--ftree-ter @gol
--ftree-sra @gol
--ftree-copyrename @gol
-ftree-fre @gol
--ftree-ch @gol
--funit-at-a-time @gol
--fmerge-constants}
+-ftree-sra @gol
+-ftree-ter @gol
+-funit-at-a-time}
@option{-O} also turns on @option{-fomit-frame-pointer} on machines
where doing so does not interfere with debugging.
@option{-O2} turns on all optimization flags specified by @option{-O}. It
also turns on the following optimization flags:
@gccoptlist{-fthread-jumps @gol
+-falign-functions -falign-jumps @gol
+-falign-loops -falign-labels @gol
+-fcaller-saves @gol
-fcrossjumping @gol
--foptimize-sibling-calls @gol
-fcse-follow-jumps -fcse-skip-blocks @gol
--fgcse -fgcse-lm @gol
+-fdelete-null-pointer-checks @gol
-fexpensive-optimizations @gol
--frerun-cse-after-loop @gol
--fcaller-saves @gol
+-fgcse -fgcse-lm @gol
+-foptimize-sibling-calls @gol
-fpeephole2 @gol
--fschedule-insns -fschedule-insns2 @gol
--fsched-interblock -fsched-spec @gol
-fregmove @gol
--fstrict-aliasing -fstrict-overflow @gol
--fdelete-null-pointer-checks @gol
-freorder-blocks -freorder-functions @gol
--falign-functions -falign-jumps @gol
--falign-loops -falign-labels @gol
--ftree-vrp @gol
--ftree-pre}
+-frerun-cse-after-loop @gol
+-fsched-interblock -fsched-spec @gol
+-fschedule-insns -fschedule-insns2 @gol
+-fstrict-aliasing -fstrict-overflow @gol
+-ftree-pre @gol
+-ftree-vrp}
Please note the warning under @option{-fgcse} about
invoking @option{-O2} on programs that use computed gotos.
Disabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
-@item -fforce-addr
-@opindex fforce-addr
-Force memory address constants to be copied into registers before
-doing arithmetic on them.
-
@item -fforward-propagate
@opindex fforward-propagate
Perform a forward propagation pass on RTL. The pass tries to combine two
is used to keep the compiler from expanding any functions inline.
Note that if you are not optimizing, no functions can be expanded inline.
+@item -finline-small-functions
+@opindex finline-small-functions
+Integrate functions into their callers when their body is smaller than expected
+function call code (so overall size of program gets smaller). The compiler
+heuristically decides which functions are simple enough to be worth integrating
+in this way.
+
+Enabled at level @option{-O2}.
+
@item -finline-functions
@opindex finline-functions
Integrate all simple functions into their callers. The compiler
optimization is turned on, use the @option{-fno-keep-static-consts} option.
@item -fmerge-constants
+@opindex fmerge-constants
Attempt to merge identical constants (string constants and floating point
constants) across compilation units.
Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -fmerge-all-constants
+@opindex fmerge-all-constants
Attempt to merge identical constants and identical variables.
This option implies @option{-fmerge-constants}. In addition to
pass. This pass looks at innermost loops and reorders their
instructions by overlapping different iterations.
+@item -fmodulo-sched-allow-regmoves
+@opindex fmodulo-sched-allow-regmoves
+Perform more aggressive SMS based modulo scheduling with register moves
+allowed. By setting this flag certain anti-dependences edges will be
+deleted which will trigger the generation of reg-moves based on the
+life-range analysis. This option is effective only with
+@option{-fmodulo-sched} enabled.
+
@item -fno-branch-count-reg
@opindex fno-branch-count-reg
Do not use ``decrement and branch'' instructions on a count register,
The default is @option{-fzero-initialized-in-bss}.
-@item -fbounds-check
-@opindex fbounds-check
-For front-ends that support it, generate additional code to check that
-indices used to access arrays are within the declared range. This is
-currently only supported by the Java and Fortran front-ends, where
-this option defaults to true and false respectively.
-
@item -fmudflap -fmudflapth -fmudflapir
@opindex fmudflap
@opindex fmudflapth
@item -fcse-follow-jumps
@opindex fcse-follow-jumps
-In common subexpression elimination, scan through jump instructions
+In common subexpression elimination (CSE), scan through jump instructions
when the target of the jump is not reached by any other path. For
example, when CSE encounters an @code{if} statement with an
@code{else} clause, CSE will follow the jump when the condition
if it finds this kind of loop.
@item -fcrossjumping
-@opindex crossjumping
+@opindex fcrossjumping
Perform cross-jumping transformation. This transformation unifies equivalent code and save code size. The
resulting code may or may not perform better than without cross-jumping.
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+@item -fauto-inc-dec
+@opindex fauto-inc-dec
+Combine increments or decrements of addresses with memory accesses.
+This pass is always skipped on architectures that do not have
+instructions to support this. Enabled by default at @option{-O} and
+higher on architectures that support this.
+
+@item -fdce
+@opindex fdce
+Perform dead code elimination (DCE) on RTL.
+Enabled by default at @option{-O} and higher.
+
+@item -fdse
+@opindex fdse
+Perform dead store elimination (DSE) on RTL.
+Enabled by default at @option{-O} and higher.
+
@item -fif-conversion
-@opindex if-conversion
+@opindex fif-conversion
Attempt to transform conditional jumps into branch-less equivalents. This
include use of conditional moves, min, max, set flags and abs instructions, and
some tricks doable by standard arithmetics. The use of conditional execution
Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -fif-conversion2
-@opindex if-conversion2
+@opindex fif-conversion2
Use conditional execution (where available) to transform conditional jumps into
branch-less equivalents.
sense when scheduling before register allocation, i.e.@: with
@option{-fschedule-insns} or at @option{-O2} or higher.
-@item -fsched-stalled-insns=@var{n}
+@item -fsched-stalled-insns
+@itemx -fsched-stalled-insns=@var{n}
@opindex fsched-stalled-insns
Define how many insns (if any) can be moved prematurely from the queue
of stalled insns into the ready list, during the second scheduling pass.
-
-@item -fsched-stalled-insns-dep=@var{n}
+@option{-fno-sched-stalled-insns} means that no insns will be moved
+prematurely, @option{-fsched-stalled-insns=0} means there is no limit
+on how many queued insns can be moved prematurely.
+@option{-fsched-stalled-insns} without a value is equivalent to
+@option{-fsched-stalled-insns=1}.
+
+@item -fsched-stalled-insns-dep
+@itemx -fsched-stalled-insns-dep=@var{n}
@opindex fsched-stalled-insns-dep
Define how many insn groups (cycles) will be examined for a dependency
on a stalled insn that is candidate for premature removal from the queue
-of stalled insns. Has an effect only during the second scheduling pass,
-and only if @option{-fsched-stalled-insns} is used and its value is not zero.
+of stalled insns. This has an effect only during the second scheduling pass,
+and only if @option{-fsched-stalled-insns} is used.
+@option{-fno-sched-stalled-insns-dep} is equivalent to
+@option{-fsched-stalled-insns-dep=0}.
+@option{-fsched-stalled-insns-dep} without a value is equivalent to
+@option{-fsched-stalled-insns-dep=1}.
@item -fsched2-use-superblocks
@opindex fsched2-use-superblocks
@item -fsee
@opindex fsee
-Eliminates redundant extension instructions and move the non redundant
-ones to optimal placement using LCM.
+Eliminate redundant sign extension instructions and move the non-redundant
+ones to optimal placement using lazy code motion (LCM).
@item -freschedule-modulo-scheduled-loops
-@opindex fscheduling-in-modulo-scheduled-loops
-The modulo scheduling comes before the traditional scheduling, if a loop was modulo scheduled
-we may want to prevent the later scheduling passes from changing its schedule, we use this
-option to control that.
+@opindex freschedule-modulo-scheduled-loops
+The modulo scheduling comes before the traditional scheduling, if a loop
+was modulo scheduled we may want to prevent the later scheduling passes
+from changing its schedule, we use this option to control that.
@item -fcaller-saves
@opindex fcaller-saves
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+@item -ftree-reassoc
+@opindex ftree-reassoc
+Perform reassociation on trees. This flag is enabled by default
+at @option{-O} and higher.
+
@item -ftree-pre
-Perform Partial Redundancy Elimination (PRE) on trees. This flag is
+@opindex ftree-pre
+Perform partial redundancy elimination (PRE) on trees. This flag is
enabled by default at @option{-O2} and @option{-O3}.
@item -ftree-fre
-Perform Full Redundancy Elimination (FRE) on trees. The difference
+@opindex ftree-fre
+Perform full redundancy elimination (FRE) on trees. The difference
between FRE and PRE is that FRE only considers expressions
that are computed on all paths leading to the redundant computation.
This analysis is faster than PRE, though it exposes fewer redundancies.
This flag is enabled by default at @option{-O} and higher.
@item -ftree-copy-prop
+@opindex ftree-copy-prop
Perform copy propagation on trees. This pass eliminates unnecessary
copy operations. This flag is enabled by default at @option{-O} and
higher.
-@item -ftree-store-copy-prop
-Perform copy propagation of memory loads and stores. This pass
-eliminates unnecessary copy operations in memory references
-(structures, global variables, arrays, etc). This flag is enabled by
-default at @option{-O2} and higher.
-
@item -ftree-salias
+@opindex ftree-salias
Perform structural alias analysis on trees. This flag
is enabled by default at @option{-O} and higher.
+@item -fipa-pure-const
+@opindex fipa-pure-const
+Discover which functions are pure or constant.
+Enabled by default at @option{-O} and higher.
+
+@item -fipa-reference
+@opindex fipa-reference
+Discover which static variables do not escape cannot escape the
+compilation unit.
+Enabled by default at @option{-O} and higher.
+
+@item -fipa-struct-reorg
+@opindex fipa-struct-reorg
+Perform structure reorganization optimization, that change C-like structures
+layout in order to better utilize spatial locality. This transformation is
+affective for programs containing arrays of structures. Available in two
+compilation modes: profile-based (enabled with @option{-fprofile-generate})
+or static (which uses built-in heuristics). Require @option{-fipa-type-escape}
+to provide the safety of this transformation. It works only in whole program
+mode, so it requires @option{-fwhole-program} and @option{-combine} to be
+enabled. Structures considered @samp{cold} by this transformation are not
+affected (see @option{--param struct-reorg-cold-struct-ratio=@var{value}}).
+
+With this flag, the program debug info reflects a new structure layout.
+
@item -fipa-pta
+@opindex fipa-pta
Perform interprocedural pointer analysis.
+@item -fipa-cp
+@opindex fipa-cp
+Perform interprocedural constant propagation.
+This optimization analyzes the program to determine when values passed
+to functions are constants and then optimizes accordingly.
+This optimization can substantially increase performance
+if the application has constants passed to functions, but
+because this optimization can create multiple copies of functions,
+it may significantly increase code size.
+
+@item -fipa-matrix-reorg
+@opindex fipa-matrix-reorg
+Perform matrix flattening and transposing.
+Matrix flattening tries to replace a m-dimensional matrix
+with its equivalent n-dimensional matrix, where n < m.
+This reduces the level of indirection needed for accessing the elements
+of the matrix. The second optimization is matrix transposing that
+attemps to change the order of the matrix's dimensions in order to
+improve cache locality.
+Both optimizations need fwhole-program flag.
+Transposing is enabled only if profiling information is avaliable.
+
+
@item -ftree-sink
+@opindex ftree-sink
Perform forward store motion on trees. This flag is
enabled by default at @option{-O} and higher.
@item -ftree-ccp
+@opindex ftree-ccp
Perform sparse conditional constant propagation (CCP) on trees. This
pass only operates on local scalar variables and is enabled by default
at @option{-O} and higher.
@item -ftree-store-ccp
+@opindex ftree-store-ccp
Perform sparse conditional constant propagation (CCP) on trees. This
pass operates on both local scalar variables and memory stores and
loads (global variables, structures, arrays, etc). This flag is
enabled by default at @option{-O2} and higher.
@item -ftree-dce
+@opindex ftree-dce
Perform dead code elimination (DCE) on trees. This flag is enabled by
default at @option{-O} and higher.
@item -ftree-dominator-opts
+@opindex ftree-dominator-opts
Perform a variety of simple scalar cleanups (constant/copy
propagation, redundancy elimination, range propagation and expression
simplification) based on a dominator tree traversal. This also
performs jump threading (to reduce jumps to jumps). This flag is
enabled by default at @option{-O} and higher.
+@item -ftree-dse
+@opindex ftree-dse
+Perform dead store elimination (DSE) on trees. A dead store is a store into
+a memory location which will later be overwritten by another store without
+any intervening loads. In this case the earlier store can be deleted. This
+flag is enabled by default at @option{-O} and higher.
+
@item -ftree-ch
+@opindex ftree-ch
Perform loop header copying on trees. This is beneficial since it increases
effectiveness of code motion optimizations. It also saves one jump. This flag
is enabled by default at @option{-O} and higher. It is not enabled
for @option{-Os}, since it usually increases code size.
@item -ftree-loop-optimize
+@opindex ftree-loop-optimize
Perform loop optimizations on trees. This flag is enabled by default
at @option{-O} and higher.
@item -ftree-loop-linear
+@opindex ftree-loop-linear
Perform linear loop transformations on tree. This flag can improve cache
performance and allow further loop optimizations to take place.
@item -fcheck-data-deps
+@opindex fcheck-data-deps
Compare the results of several data dependence analyzers. This option
is used for debugging the data dependence analyzers.
@item -ftree-loop-im
+@opindex ftree-loop-im
Perform loop invariant motion on trees. This pass moves only invariants that
would be hard to handle at RTL level (function calls, operations that expand to
nontrivial sequences of insns). With @option{-funswitch-loops} it also moves
store motion.
@item -ftree-loop-ivcanon
+@opindex ftree-loop-ivcanon
Create a canonical counter for number of iterations in the loop for that
determining number of iterations requires complicated analysis. Later
optimizations then may determine the number easily. Useful especially
in connection with unrolling.
@item -fivopts
+@opindex fivopts
Perform induction variable optimizations (strength reduction, induction
variable merging and induction variable elimination) on trees.
+@item -ftree-parallelize-loops=n
+@opindex ftree-parallelize-loops
+Parallelize loops, i.e., split their iteration space to run in n threads.
+This is only possible for loops whose iterations are independent
+and can be arbitrarily reordered. The optimization is only
+profitable on multiprocessor machines, for loops that are CPU-intensive,
+rather than constrained e.g. by memory bandwidth. This option
+implies @option{-pthread}, and thus is only supported on targets
+that have support for @option{-pthread}.
+
@item -ftree-sra
+@opindex ftree-sra
Perform scalar replacement of aggregates. This pass replaces structure
references with scalars to prevent committing structures to memory too
early. This flag is enabled by default at @option{-O} and higher.
@item -ftree-copyrename
+@opindex ftree-copyrename
Perform copy renaming on trees. This pass attempts to rename compiler
temporaries to other variables at copy locations, usually resulting in
variable names which more closely resemble the original variables. This flag
is enabled by default at @option{-O} and higher.
@item -ftree-ter
+@opindex ftree-ter
Perform temporary expression replacement during the SSA->normal phase. Single
use/single def temporaries are replaced at their use location with their
defining expression. This results in non-GIMPLE code, but gives the expanders
enabled by default at @option{-O} and higher.
@item -ftree-vectorize
+@opindex ftree-vectorize
Perform loop vectorization on trees.
@item -ftree-vect-loop-version
except at level @option{-Os} where it is disabled.
@item -fvect-cost-model
+@opindex fvect-cost-model
Enable cost model for vectorization.
@item -ftree-vrp
+@opindex ftree-vrp
Perform Value Range Propagation on trees. This is similar to the
constant propagation pass, but instead of values, ranges of values are
propagated. This allows the optimizers to remove unnecessary range
Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -fno-toplevel-reorder
+@opindex fno-toplevel-reorder
Do not reorder top-level functions, variables, and @code{asm}
statements. Output them in the same order that they appear in the
input file. When this option is used, unreferenced static variables
programs since the functions and variables become local for the whole combined
compilation unit, not for the single source file itself.
+This option is not supported for Fortran programs.
-@item -fno-cprop-registers
-@opindex fno-cprop-registers
+@item -fcprop-registers
+@opindex fcprop-registers
After register allocation and post-register allocation instruction splitting,
we perform a copy-propagation pass to try to reduce scheduling dependencies
and occasionally eliminate the copy.
-Disabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
+Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -fprofile-generate
@opindex fprofile-generate
@item -ffast-math
@opindex ffast-math
-Sets @option{-fno-math-errno}, @option{-funsafe-math-optimizations}, @*
-@option{-fno-trapping-math}, @option{-ffinite-math-only},
-@option{-fno-rounding-math}, @option{-fno-signaling-nans},
-@option{-fno-signed-zeros} and @option{fcx-limited-range}.
+Sets @option{-fno-math-errno}, @option{-funsafe-math-optimizations},
+@option{-ffinite-math-only}, @option{-fno-rounding-math},
+@option{-fno-signaling-nans} and @option{-fcx-limited-range}.
This option causes the preprocessor macro @code{__FAST_MATH__} to be defined.
@item -funsafe-math-optimizations
@opindex funsafe-math-optimizations
+
Allow optimizations for floating-point arithmetic that (a) assume
that arguments and results are valid and (b) may violate IEEE or
ANSI standards. When used at link-time, it may include libraries
an exact implementation of IEEE or ISO rules/specifications for
math functions. It may, however, yield faster code for programs
that do not require the guarantees of these specifications.
+Enables @option{-fno-signed-zeros}, @option{-fno-trapping-math},
+@option{-fassociative-math} and @option{-freciprocal-math}.
The default is @option{-fno-unsafe-math-optimizations}.
+@item -fassociative-math
+@opindex fassociative-math
+
+Allow re-association of operands in series of floating-point operations.
+This violates the ISO C and C++ language standard by possibly changing
+computation result. NOTE: re-ordering may change the sign of zero as
+well as ignore NaNs and inhibit or create underflow or overflow (and
+thus cannot be used on a code which relies on rounding behavior like
+@code{(x + 2**52) - 2**52)}. May also reorder floating-point comparisons
+and thus may not be used when ordered comparisons are required.
+This option requires that both @option{-fno-signed-zeros} and
+@option{-fno-trapping-math} be in effect. Moreover, it doesn't make
+much sense with @option{-frounding-math}.
+
+The default is @option{-fno-associative-math}.
+
+@item -freciprocal-math
+@opindex freciprocal-math
+
+Allow the reciprocal of a value to be used instead of dividing by
+the value if this enables optimizations. For example @code{x / y}
+can be replaced with @code{x * (1/y)} which is useful if @code{(1/y)}
+is subject to common subexpression elimination. Note that this loses
+precision and increases the number of flops operating on the value.
+
+The default is @option{-fno-reciprocal-math}.
+
@item -ffinite-math-only
@opindex ffinite-math-only
Allow optimizations for floating-point arithmetic that assume
@opindex fno-trapping-math
Compile code assuming that floating-point operations cannot generate
user-visible traps. These traps include division by zero, overflow,
-underflow, inexact result and invalid operation. This option implies
-@option{-fno-signaling-nans}. Setting this option may allow faster
-code if one relies on ``non-stop'' IEEE arithmetic, for example.
+underflow, inexact result and invalid operation. This option requires
+that @option{-fno-signaling-nans} be in effect. Setting this option may
+allow faster code if one relies on ``non-stop'' IEEE arithmetic, for example.
This option should never be turned on by any @option{-O} option since
it can result in incorrect output for programs which depend on
implicitly converting it to double precision constant.
@item -fcx-limited-range
-@itemx -fno-cx-limited-range
@opindex fcx-limited-range
-@opindex fno-cx-limited-range
When enabled, this option states that a range reduction step is not
needed when performing complex division. The default is
@option{-fno-cx-limited-range}, but is enabled by @option{-ffast-math}.
branch target registers in within any basic block.
@item -fstack-protector
+@opindex fstack-protector
Emit extra code to check for buffer overflows, such as stack smashing
attacks. This is done by adding a guard variable to functions with
vulnerable objects. This includes functions that call alloca, and
If a guard check fails, an error message is printed and the program exits.
@item -fstack-protector-all
+@opindex fstack-protector-all
Like @option{-fstack-protector} except that all functions are protected.
@item -fsection-anchors
structure exceeds this parameter, then block copies are not used. The
default is 75.
+@item struct-reorg-cold-struct-ratio
+The threshold ratio (as a percentage) between a structure frequency
+and the frequency of the hottest structure in the program. This parameter
+is used by struct-reorg optimization enabled by @option{-fipa-struct-reorg}.
+We say that if the ratio of a structure frequency, calculated by profiling,
+to the hottest structure frequency in the program is less than this
+parameter, then structure reorganization is not applied to this structure.
+The default is 10.
+
@item max-crossjump-edges
The maximum number of incoming edges to consider for crossjumping.
The algorithm used by @option{-fcrossjumping} is @math{O(N^2)} in
taken into account. For function not declared inline, recursive inlining
happens only when @option{-finline-functions} (included in @option{-O3}) is
enabled and @option{--param max-inline-recursive-depth-auto} is used. The
-default value is 450.
+default value is 8.
@item min-inline-recursive-probability
Recursive inlining is profitable only for function having deep recursion
reduce function size by being inlined. In effect it increases amount of
inlining for code having large abstraction penalty (many functions that just
pass the arguments to other functions) and decrease inlining for code with low
-abstraction penalty. The default value is 16.
+abstraction penalty. The default value is 12.
@item min-vect-loop-bound
The minimum number of iterations under which a loop will not get vectorized
When set to 1, use expensive methods to eliminate all redundant
constraints. The default value is 0.
-@item vect-max-version-checks
-The maximum number of runtime checks that can be performed when doing
-loop versioning in the vectorizer. See option ftree-vect-loop-version
-for more information.
+@item vect-max-version-for-alignment-checks
+The maximum number of runtime checks that can be performed when
+doing loop versioning for alignment in the vectorizer. See option
+ftree-vect-loop-version for more information.
+
+@item vect-max-version-for-alias-checks
+The maximum number of runtime checks that can be performed when
+doing loop versioning for alias in the vectorizer. See option
+ftree-vect-loop-version for more information.
@item max-iterations-to-track
the unknown number of iterations average to roughly 10. This means that the
loop without bounds would appear artificially cold relative to the other one.
+@item align-threshold
+
+Select fraction of the maximal frequency of executions of basic block in
+function given basic block will get aligned.
+
+@item align-loop-iterations
+
+A loop expected to iterate at lest the selected number of iterations will get
+aligned.
+
@item tracer-dynamic-coverage
@itemx tracer-dynamic-coverage-feedback
The size of cache line in L1 cache, in bytes.
@item l1-cache-size
-The number of cache lines in L1 cache.
-
-@item verify-canonical-types
-Whether the compiler should verify the ``canonical'' types used for
-type equality comparisons within the C++ and Objective-C++ front
-ends. Set to 1 (the default when GCC is configured with
---enable-checking) to enable verification, 0 to disable verification
-(the default when GCC is configured with --disable-checking).
+The size of L1 cache, in kilobytes.
+
+@item l2-cache-size
+The size of L2 cache, in kilobytes.
+
+@item use-canonical-types
+Whether the compiler should use the ``canonical'' type system. By
+default, this should always be 1, which uses a more efficient internal
+mechanism for comparing types in C++ and Objective-C++. However, if
+bugs in the canonical type system are causing compilation failures,
+set this value to 0 to disable canonical types.
+
+@item max-partial-antic-length
+Maximum length of the partial antic set computed during the tree
+partial redundancy elimination optimization (@option{-ftree-pre}) when
+optimizing at @option{-O3} and above. For some sorts of source code
+the enhanced partial redundancy elimination optimization can run away,
+consuming all of the memory available on the host machine. This
+parameter sets a limit on the length of the sets that are computed,
+which prevents the runaway behaviour. Setting a value of 0 for
+this paramter will allow an unlimited set length.
+
+@item sccvn-max-scc-size
+Maximum size of a strongly connected component (SCC) during SCCVN
+processing. If this limit is hit, SCCVN processing for the whole
+function will not be done and optimizations depending on it will
+be disabled. The default maximum SCC size is 10000.
@end table
@end table
@cindex Blackfin Options
@table @gcctabopt
-@item -mcpu=@var{cpu}
+@item -mcpu=@var{cpu}@r{[}-@var{sirevision}@r{]}
@opindex mcpu=
-Specifies the name of the target Blackfin processor. Currently, @var{cpu}
-can be one of @samp{bf531}, @samp{bf532}, @samp{bf533},
-@samp{bf534}, @samp{bf536}, @samp{bf537}, @samp{bf561}.
+Specifies the name of the target Blackfin processor. Currently, @var{cpu}
+can be one of @samp{bf522}, @samp{bf525}, @samp{bf527},
+@samp{bf531}, @samp{bf532}, @samp{bf533}, @samp{bf534},
+@samp{bf536}, @samp{bf537}, @samp{bf538}, @samp{bf539},
+@samp{bf542}, @samp{bf544}, @samp{bf548}, @samp{bf549},
+@samp{bf561}.
+The optional @var{sirevision} specifies the silicon revision of the target
+Blackfin processor. Any workarounds available for the targeted silicon revision
+will be enabled. If @var{sirevision} is @samp{none}, no workarounds are enabled.
+If @var{sirevision} is @samp{any}, all workarounds for the targeted processor
+will be enabled. The @code{__SILICON_REVISION__} macro is defined to two
+hexadecimal digits representing the major and minor numbers in the silicon
+revision. If @var{sirevision} is @samp{none}, the @code{__SILICON_REVISION__}
+is not defined. If @var{sirevision} is @samp{any}, the
+@code{__SILICON_REVISION__} is defined to be @code{0xffff}.
+If this optional @var{sirevision} is not used, GCC assumes the latest known
+silicon revision of the targeted Blackfin processor.
+
+Support for @samp{bf561} is incomplete. For @samp{bf561},
+Only the processor macro is defined.
Without this option, @samp{bf532} is used as the processor by default.
The corresponding predefined processor macros for @var{cpu} is to
-be defined. For the @samp{bfin-elf} toolchain, this causes the hardware
-BSP provided by libgloss to be linked in if @samp{-msim} is not given.
-Support for @samp{bf561} is incomplete; only the processor macro is defined.
+be defined. And for @samp{bfin-elf} toolchain, this causes the hardware BSP
+provided by libgloss to be linked in if @option{-msim} is not given.
@item -msim
@opindex msim
Specifies that the program will be run on the simulator. This causes
the simulator BSP provided by libgloss to be linked in. This option
has effect only for @samp{bfin-elf} toolchain.
+Certain other options, such as @option{-mid-shared-library} and
+@option{-mfdpic}, imply @option{-msim}.
@item -momit-leaf-frame-pointer
@opindex momit-leaf-frame-pointer
@item -mspecld-anomaly
@opindex mspecld-anomaly
When enabled, the compiler will ensure that the generated code does not
-contain speculative loads after jump instructions. This option is enabled
-by default.
+contain speculative loads after jump instructions. If this option is used,
+@code{__WORKAROUND_SPECULATIVE_LOADS} is defined.
@item -mno-specld-anomaly
@opindex mno-specld-anomaly
@opindex mcsync-anomaly
When enabled, the compiler will ensure that the generated code does not
contain CSYNC or SSYNC instructions too soon after conditional branches.
-This option is enabled by default.
+If this option is used, @code{__WORKAROUND_SPECULATIVE_SYNCS} is defined.
@item -mno-csync-anomaly
@opindex mno-csync-anomaly
Generate code that supports shared libraries via the library ID method.
This allows for execute in place and shared libraries in an environment
without virtual memory management. This option implies @option{-fPIC}.
+With a @samp{bfin-elf} target, this option implies @option{-msim}.
@item -mno-id-shared-library
@opindex mno-id-shared-library
@option{-mno-long-calls} will restore the default behavior. Note these
switches have no effect on how the compiler generates code to handle
function calls via function pointers.
+
+@item -mfast-fp
+@opindex mfast-fp
+Link with the fast floating-point library. This library relaxes some of
+the IEEE floating-point standard's rules for checking inputs against
+Not-a-Number (NAN), in the interest of performance.
+
+@item -minline-plt
+@opindex minline-plt
+Enable inlining of PLT entries in function calls to functions that are
+not known to bind locally. It has no effect without @option{-mfdpic}.
@end table
@node CRIS Options
@item -mvms-return-codes
@opindex mvms-return-codes
Return VMS condition codes from main. The default is to return POSIX
-style condition (e.g.@ error) codes.
+style condition (e.g.@: error) codes.
@end table
@node FRV Options
assumes GOT entries and small data are within a 12-bit range from the
GOT base address; with @option{-fPIC} or @option{-fPIE}, GOT offsets
are computed with 32 bits.
+With a @samp{bfin-elf} target, this option implies @option{-msim}.
@item -minline-plt
@opindex minline-plt
@itemx -mno-sse4
@item -msse4a
@item -mno-sse4a
+@item -msse5
+@itemx -mno-sse5
@item -m3dnow
@itemx -mno-3dnow
@item -mpopcnt
@opindex m3dnow
@opindex mno-3dnow
These switches enable or disable the use of instructions in the MMX,
-SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4A, ABM or 3DNow! extended
+SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4A, SSE5, ABM or 3DNow! extended
instruction sets.
These extensions are also available as built-in functions: see
@ref{X86 Built-in Functions}, for details of the functions enabled and
@item -mrecip
@opindex mrecip
This option will enable GCC to use RCPSS and RSQRTSS instructions (and their
-vectorized variants RCPPS and RSQRTPS) instead of DIVSS and SQRTSS (and their
-vectorized variants). These instructions will be generated only when
-@option{-funsafe-math-optimizatons} is enabled.
+vectorized variants RCPPS and RSQRTPS) with an additional Newton-Rhapson step
+to increase precision instead of DIVSS and SQRTSS (and their vectorized
+variants) for single precision floating point arguments. These instructions
+are generated only when @option{-funsafe-math-optimizations} is enabled
+together with @option{-finite-math-only} and @option{-fno-trapping-math}.
+Note that while the throughput of the sequence is higher than the throughput
+of the non-reciprocal instruction, the precision of the sequence can be
+decreased by up to 2 ulp (i.e. the inverse of 1.0 equals 0.99999994).
+
+@item -mveclibabi=@var{type}
+@opindex mveclibabi
+Specifies the ABI type to use for vectorizing intrinsics using an
+external library. Supported types are @code{acml} for the AMD
+math core library style of interfacing. GCC will currently emit
+calls to @code{__vrd2_sin}, @code{__vrd2_cos}, @code{__vrd2_exp},
+@code{__vrd2_log}, @code{__vrd2_log2}, @code{__vrd2_log10},
+@code{__vrs4_sinf}, @code{__vrs4_cosf}, @code{__vrs4_expf},
+@code{__vrs4_logf}, @code{__vrs4_log2f}, @code{__vrs4_log10f}
+and @code{__vrs4_powf} when using this type and @option{-ftree-vectorize}
+is enabled. A ACML ABI compatible library will have to be specified
+at link time.
@item -mpush-args
@itemx -mno-push-args
segment to cover the entire TLS area.
For systems that use GNU libc, the default is on.
+
+@item -mfused-madd
+@itemx -mno-fused-madd
+@opindex mfused-madd
+Enable automatic generation of fused floating point multiply-add instructions
+if the ISA supports such instructions. The -mfused-madd option is on by
+default. The fused multiply-add instructions have a different
+rounding behavior compared to executing a multiply followed by an add.
@end table
These @samp{-m} switches are supported in addition to the above
@multitable @columnfractions 0.20 0.80
@item @strong{Family} @tab @strong{@samp{-mcpu} arguments}
+@item @samp{51qe} @tab @samp{51qe}
@item @samp{5206} @tab @samp{5202} @samp{5204} @samp{5206}
@item @samp{5206e} @tab @samp{5206e}
@item @samp{5208} @tab @samp{5207} @samp{5208}
The M680x0 microarchitectures are: @samp{68000}, @samp{68010},
@samp{68020}, @samp{68030}, @samp{68040}, @samp{68060}
and @samp{cpu32}. The ColdFire microarchitectures
-are: @samp{cfv2}, @samp{cfv3}, @samp{cfv4} and @samp{cfv4e}.
+are: @samp{cfv1}, @samp{cfv2}, @samp{cfv3}, @samp{cfv4} and @samp{cfv4e}.
You can also use @option{-mtune=68020-40} for code that needs
to run relatively well on 68020, 68030 and 68040 targets.
@samp{mips1}, @samp{mips2}, @samp{mips3}, @samp{mips4},
@samp{mips32}, @samp{mips32r2}, and @samp{mips64}.
The processor names are:
-@samp{4kc}, @samp{4km}, @samp{4kp},
-@samp{4kec}, @samp{4kem}, @samp{4kep},
+@samp{4kc}, @samp{4km}, @samp{4kp}, @samp{4ksc},
+@samp{4kec}, @samp{4kem}, @samp{4kep}, @samp{4ksd},
@samp{5kc}, @samp{5kf},
@samp{20kc},
@samp{24kc}, @samp{24kf2_1}, @samp{24kf1_1},
@samp{24kec}, @samp{24kef2_1}, @samp{24kef1_1},
@samp{34kc}, @samp{34kf2_1}, @samp{34kf1_1},
-@samp{74kc}, @samp{74kf2_1}, @samp{74kf1_1},
+@samp{74kc}, @samp{74kf2_1}, @samp{74kf1_1}, @samp{74kf3_2},
@samp{m4k},
@samp{orion},
@samp{r2000}, @samp{r3000}, @samp{r3900}, @samp{r4000}, @samp{r4400},
@samp{vr} may be written @samp{r}.
Names of the form @samp{@var{n}f2_1} refer to processors with
-FPUs clocked at half the rate of the core. Names of the form
+FPUs clocked at half the rate of the core, names of the form
@samp{@var{n}f1_1} refer to processors with FPUs clocked at the same
-rate as the core. For compatibility reasons, @samp{@var{n}f} is
-accepted as a synonym for @samp{@var{n}f2_1} while @samp{@var{n}x} and
-@samp{@var{b}fx} are accepted as synonyms for @samp{@var{n}f1_1}.
+rate as the core, and names of the form @samp{@var{n}f3_2} refer to
+processors with FPUs clocked a ratio of 3:2 with respect to the core.
+For compatibility reasons, @samp{@var{n}f} is accepted as a synonym
+for @samp{@var{n}f2_1} while @samp{@var{n}x} and @samp{@var{b}fx} are
+accepted as synonyms for @samp{@var{n}f1_1}.
GCC defines two macros based on the value of this option. The first
is @samp{_MIPS_ARCH}, which gives the name of target architecture, as
Generate (do not generate) MIPS16 code. If GCC is targetting a
MIPS32 or MIPS64 architecture, it will make use of the MIPS16e ASE@.
+MIPS16 code generation can also be controlled on a per-function basis
+by means of @code{mips16} and @code{nomips16} attributes.
+@xref{Function Attributes}, for more information.
+
+@item -mflip-mips16
+@opindex mflip-mips16
+Generate MIPS16 code on alternating functions. This option is provided
+for regression testing of mixed MIPS16/non-MIPS16 code generation, and is
+not intended for ordinary use in compiling user code.
+
+@item -minterlink-mips16
+@itemx -mno-interlink-mips16
+@opindex minterlink-mips16
+@opindex mno-interlink-mips16
+Require (do not require) that non-MIPS16 code be link-compatible with
+MIPS16 code.
+
+For example, non-MIPS16 code cannot jump directly to MIPS16 code;
+it must either use a call or an indirect jump. @option{-minterlink-mips16}
+therefore disables direct jumps unless GCC knows that the target of the
+jump is not MIPS16.
+
@item -mabi=32
@itemx -mabi=o64
@itemx -mabi=n32
Assume that the floating-point coprocessor supports double-precision
operations. This is the default.
+@item -mllsc
+@itemx -mno-llsc
+@opindex mllsc
+@opindex mno-llsc
+Use (do not use) @samp{ll}, @samp{sc}, and @samp{sync} instructions to
+implement atomic memory built-in functions. When neither option is
+specified, GCC will use the instructions if the target architecture
+supports them.
+
+@option{-mllsc} is useful if the runtime environment can emulate the
+instructions and @option{-mno-llsc} can be useful when compiling for
+nonstandard ISAs. You can make either option the default by
+configuring GCC with @option{--with-llsc} and @option{--without-llsc}
+respectively. @option{--with-llsc} is the default for some
+configurations; see the installation documentation for details.
+
@item -mdsp
@itemx -mno-dsp
@opindex mdsp
@opindex mno-dsp
-Use (do not use) the MIPS DSP ASE. @xref{MIPS DSP Built-in Functions}.
+Use (do not use) revision 1 of the MIPS DSP ASE.
+@xref{MIPS DSP Built-in Functions}. This option defines the
+preprocessor macro @samp{__mips_dsp}. It also defines
+@samp{__mips_dsp_rev} to 1.
@item -mdspr2
@itemx -mno-dspr2
@opindex mdspr2
@opindex mno-dspr2
-Use (do not use) the MIPS DSP ASE REV 2. @xref{MIPS DSP Built-in Functions}.
-The option @option{-mdspr2} implies @option{-mdsp}.
+Use (do not use) revision 2 of the MIPS DSP ASE.
+@xref{MIPS DSP Built-in Functions}. This option defines the
+preprocessor macros @samp{__mips_dsp} and @samp{__mips_dspr2}.
+It also defines @samp{__mips_dsp_rev} to 2.
+
+@item -msmartmips
+@itemx -mno-smartmips
+@opindex msmartmips
+@opindex mno-smartmips
+Use (do not use) the MIPS SmartMIPS ASE.
@item -mpaired-single
@itemx -mno-paired-single
@opindex mpaired-single
@opindex mno-paired-single
Use (do not use) paired-single floating-point instructions.
-@xref{MIPS Paired-Single Support}. This option can only be used
-when generating 64-bit code and requires hardware floating-point
-support to be enabled.
+@xref{MIPS Paired-Single Support}. This option requires
+hardware floating-point support to be enabled.
@item -mdmx
@itemx -mno-mdmx
@item -G @var{num}
@opindex G
-@cindex smaller data references (MIPS)
-@cindex gp-relative references (MIPS)
-Put global and static items less than or equal to @var{num} bytes into
-the small data or bss section instead of the normal data or bss section.
-This allows the data to be accessed using a single instruction.
+Put definitions of externally-visible data in a small data section
+if that data is no bigger than @var{num} bytes. GCC can then access
+the data more efficiently; see @option{-mgpopt} for details.
+
+The default @option{-G} option depends on the configuration.
+
+@item -mlocal-sdata
+@itemx -mno-local-sdata
+@opindex mlocal-sdata
+@opindex mno-local-sdata
+Extend (do not extend) the @option{-G} behavior to local data too,
+such as to static variables in C. @option{-mlocal-sdata} is the
+default for all configurations.
+
+If the linker complains that an application is using too much small data,
+you might want to try rebuilding the less performance-critical parts with
+@option{-mno-local-sdata}. You might also want to build large
+libraries with @option{-mno-local-sdata}, so that the libraries leave
+more room for the main program.
+
+@item -mextern-sdata
+@itemx -mno-extern-sdata
+@opindex mextern-sdata
+@opindex mno-extern-sdata
+Assume (do not assume) that externally-defined data will be in
+a small data section if that data is within the @option{-G} limit.
+@option{-mextern-sdata} is the default for all configurations.
+
+If you compile a module @var{Mod} with @option{-mextern-sdata} @option{-G
+@var{num}} @option{-mgpopt}, and @var{Mod} references a variable @var{Var}
+that is no bigger than @var{num} bytes, you must make sure that @var{Var}
+is placed in a small data section. If @var{Var} is defined by another
+module, you must either compile that module with a high-enough
+@option{-G} setting or attach a @code{section} attribute to @var{Var}'s
+definition. If @var{Var} is common, you must link the application
+with a high-enough @option{-G} setting.
+
+The easiest way of satisfying these restrictions is to compile
+and link every module with the same @option{-G} option. However,
+you may wish to build a library that supports several different
+small data limits. You can do this by compiling the library with
+the highest supported @option{-G} setting and additionally using
+@option{-mno-extern-sdata} to stop the library from making assumptions
+about externally-defined data.
+
+@item -mgpopt
+@itemx -mno-gpopt
+@opindex mgpopt
+@opindex mno-gpopt
+Use (do not use) GP-relative accesses for symbols that are known to be
+in a small data section; see @option{-G}, @option{-mlocal-sdata} and
+@option{-mextern-sdata}. @option{-mgpopt} is the default for all
+configurations.
-All modules should be compiled with the same @option{-G @var{num}}
-value.
+@option{-mno-gpopt} is useful for cases where the @code{$gp} register
+might not hold the value of @code{_gp}. For example, if the code is
+part of a library that might be used in a boot monitor, programs that
+call boot monitor routines will pass an unknown value in @code{$gp}.
+(In such situations, the boot monitor itself would usually be compiled
+with @option{-G0}.)
+
+@option{-mno-gpopt} implies @option{-mno-local-sdata} and
+@option{-mno-extern-sdata}.
@item -membedded-data
@itemx -mno-embedded-data
Put uninitialized @code{const} variables in the read-only data section.
This option is only meaningful in conjunction with @option{-membedded-data}.
+@item -mcode-readable=@var{setting}
+@opindex mcode-readable
+Specify whether GCC may generate code that reads from executable sections.
+There are three possible settings:
+
+@table @gcctabopt
+@item -mcode-readable=yes
+Instructions may freely access executable sections. This is the
+default setting.
+
+@item -mcode-readable=pcrel
+MIPS16 PC-relative load instructions can access executable sections,
+but other instructions must not do so. This option is useful on 4KSc
+and 4KSd processors when the code TLBs have the Read Inhibit bit set.
+It is also useful on processors that can be configured to have a dual
+instruction/data SRAM interface and that, like the M4K, automatically
+redirect PC-relative loads to the instruction RAM.
+
+@item -mcode-readable=no
+Instructions must not access executable sections. This option can be
+useful on targets that are configured to have a dual instruction/data
+SRAM interface but that (unlike the M4K) do not automatically redirect
+PC-relative loads to the instruction RAM.
+@end table
+
@item -msplit-addresses
@itemx -mno-split-addresses
@opindex msplit-addresses
depends on the target GCC was configured for, but commonly is either
@samp{_flush_func} or @samp{__cpu_flush}.
+@item mbranch-cost=@var{num}
+@opindex mbranch-cost
+Set the cost of branches to roughly @var{num} ``simple'' instructions.
+This cost is only a heuristic and is not guaranteed to produce
+consistent results across releases. A zero cost redundantly selects
+the default, which is based on the @option{-mtune} setting.
+
@item -mbranch-likely
@itemx -mno-branch-likely
@opindex mbranch-likely
@itemx -mno-cmpb
@itemx -mmfpgpr
@itemx -mno-mfpgpr
-@itemx -mdfp
-@itemx -mno-dfp
+@itemx -mhard-dfp
+@itemx -mno-hard-dfp
@opindex mpower
@opindex mno-power
@opindex mpower2
@opindex mno-cmpb
@opindex mmfpgpr
@opindex mno-mfpgpr
-@opindex mdfp
-@opindex mno-dfp
+@opindex mhard-dfp
+@opindex mno-hard-dfp
GCC supports two related instruction set architectures for the
RS/6000 and PowerPC@. The @dfn{POWER} instruction set are those
instructions supported by the @samp{rios} chip set used in the original
general purpose register instructions implemented on the POWER6X
processor and other processors that support the extended PowerPC V2.05
architecture.
-The @option{-mdfp} option allows GCC to generate the decimal floating
+The @option{-mhard-dfp} option allows GCC to generate the decimal floating
point instructions implemented on some POWER processors.
The @option{-mpowerpc64} option allows GCC to generate the additional
This switch enables or disables the generation of SPE simd
instructions.
+@item -mpaired
+@itemx -mno-paired
+@opindex mpaired
+@opindex mno-paired
+This switch enables or disables the generation of PAIRED simd
+instructions.
+
@item -mspe=@var{yes/no}
This option has been deprecated. Use @option{-mspe} and
@option{-mno-spe} instead.
@samp{v7}, @samp{cypress}, @samp{v8}, @samp{supersparc}, @samp{sparclite},
@samp{f930}, @samp{f934}, @samp{hypersparc}, @samp{sparclite86x},
@samp{sparclet}, @samp{tsc701}, @samp{v9}, @samp{ultrasparc},
-@samp{ultrasparc3}, and @samp{niagara}.
+@samp{ultrasparc3}, @samp{niagara} and @samp{niagara2}.
Default instruction scheduling parameters are used for values that select
an architecture and not an implementation. These are @samp{v7}, @samp{v8},
v8: supersparc, hypersparc
sparclite: f930, f934, sparclite86x
sparclet: tsc701
- v9: ultrasparc, ultrasparc3, niagara
+ v9: ultrasparc, ultrasparc3, niagara, niagara2
@end smallexample
By default (unless configured otherwise), GCC generates code for the V7
@option{-mcpu=ultrasparc3}, the compiler additionally optimizes it for the
Sun UltraSPARC III/III+/IIIi/IIIi+/IV/IV+ chips. With
@option{-mcpu=niagara}, the compiler additionally optimizes it for
-Sun UltraSPARC T1 chips.
+Sun UltraSPARC T1 chips. With @option{-mcpu=niagara2}, the compiler
+additionally optimizes it for Sun UltraSPARC T2 chips.
@item -mtune=@var{cpu_type}
@opindex mtune
that select a particular cpu implementation. Those are @samp{cypress},
@samp{supersparc}, @samp{hypersparc}, @samp{f930}, @samp{f934},
@samp{sparclite86x}, @samp{tsc701}, @samp{ultrasparc},
-@samp{ultrasparc3}, and @samp{niagara}.
+@samp{ultrasparc3}, @samp{niagara}, and @samp{niagara2}.
@item -mv8plus
@itemx -mno-v8plus
cannot safely be called (perhaps signal handlers, if the profiling
routines generate output or allocate memory).
+@item -finstrument-functions-exclude-file-list=@var{file},@var{file},@dots{}
+@opindex finstrument-functions-exclude-file-list
+
+Set the list of functions that are excluded from instrumentation (see
+the description of @code{-finstrument-functions}). If the file that
+contains a function definition matches with one of @var{file}, then
+that function is not instrumented. The match is done on substrings:
+if the @var{file} parameter is a substring of the file name, it is
+considered to be a match.
+
+For example,
+@code{-finstrument-functions-exclude-file-list=/bits/stl,include/sys}
+will exclude any inline function defined in files whose pathnames
+contain @code{/bits/stl} or @code{include/sys}.
+
+If, for some reason, you want to include letter @code{','} in one of
+@var{sym}, write @code{'\,'}. For example,
+@code{-finstrument-functions-exclude-file-list='\,\,tmp'}
+(note the single quote surrounding the option).
+
+@item -finstrument-functions-exclude-function-list=@var{sym},@var{sym},@dots{}
+@opindex finstrument-functions-exclude-function-list
+
+This is similar to @code{-finstrument-functions-exclude-file-list},
+but this option sets the list of function names to be excluded from
+instrumentation. The function name to be matched is its user-visible
+name, such as @code{vector<int> blah(const vector<int> &)}, not the
+internal mangled name (e.g., @code{_Z4blahRSt6vectorIiSaIiEE}). The
+match is done on substrings: if the @var{sym} parameter is a substring
+of the function name, it is considered to be a match.
+
@item -fstack-check
@opindex fstack-check
Generate code to verify that you do not go beyond the boundary of the
Not all targets provide complete support for this switch.
@item -ftls-model=@var{model}
+@opindex ftls-model
Alter the thread-local storage model to be used (@pxref{Thread-Local}).
The @var{model} argument should be one of @code{global-dynamic},
@code{local-dynamic}, @code{initial-exec} or @code{local-exec}.
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