@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-@c 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+@c 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
@c Free Software Foundation, Inc.
@c This is part of the GCC manual.
@c For copying conditions, see the file gcc.texi.
@c man begin COPYRIGHT
Copyright @copyright{} 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
-1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
@table @emph
@item Overall Options
@xref{Overall Options,,Options Controlling the Kind of Output}.
-@gccoptlist{-c -S -E -o @var{file} -combine -no-canonical-prefixes @gol
+@gccoptlist{-c -S -E -o @var{file} -no-canonical-prefixes @gol
-pipe -pass-exit-codes @gol
-x @var{language} -v -### --help@r{[}=@var{class}@r{[},@dots{}@r{]]} --target-help @gol
---version -wrapper@@@var{file} -fplugin=@var{file} -fplugin-arg-@var{name}=@var{arg} @gol
--fdump-ada-spec@r{[}-slim@r{]}}
+--version -wrapper @@@var{file} -fplugin=@var{file} -fplugin-arg-@var{name}=@var{arg} @gol
+-fdump-ada-spec@r{[}-slim@r{]} -fdump-go-spec=@var{file}}
@item C Language Options
@xref{C Dialect Options,,Options Controlling C Dialect}.
@gccoptlist{-ansi -std=@var{standard} -fgnu89-inline @gol
--aux-info @var{filename} @gol
+-aux-info @var{filename} -fallow-parameterless-variadic-functions @gol
-fno-asm -fno-builtin -fno-builtin-@var{function} @gol
--fhosted -ffreestanding -fopenmp -fms-extensions @gol
+-fhosted -ffreestanding -fopenmp -fms-extensions -fplan9-extensions @gol
-trigraphs -no-integrated-cpp -traditional -traditional-cpp @gol
-fallow-single-precision -fcond-mismatch -flax-vector-conversions @gol
-fsigned-bitfields -fsigned-char @gol
@item C++ Language Options
@xref{C++ Dialect Options,,Options Controlling C++ Dialect}.
@gccoptlist{-fabi-version=@var{n} -fno-access-control -fcheck-new @gol
--fconserve-space -ffriend-injection @gol
+-fconserve-space -fconstexpr-depth=@var{n} -ffriend-injection @gol
-fno-elide-constructors @gol
-fno-enforce-eh-specs @gol
-ffor-scope -fno-for-scope -fno-gnu-keywords @gol
@gccoptlist{-fconstant-string-class=@var{class-name} @gol
-fgnu-runtime -fnext-runtime @gol
-fno-nil-receivers @gol
+-fobjc-abi-version=@var{n} @gol
-fobjc-call-cxx-cdtors @gol
-fobjc-direct-dispatch @gol
-fobjc-exceptions @gol
-fobjc-gc @gol
+-fobjc-nilcheck @gol
+-fobjc-std=objc1 @gol
-freplace-objc-classes @gol
-fzero-link @gol
-gen-decls @gol
@xref{Language Independent Options,,Options to Control Diagnostic Messages Formatting}.
@gccoptlist{-fmessage-length=@var{n} @gol
-fdiagnostics-show-location=@r{[}once@r{|}every-line@r{]} @gol
--fdiagnostics-show-option}
+-fno-diagnostics-show-option}
@item Warning Options
@xref{Warning Options,,Options to Request or Suppress Warnings}.
-@gccoptlist{-fsyntax-only -pedantic -pedantic-errors @gol
+@gccoptlist{-fsyntax-only -fmax-errors=@var{n} -pedantic @gol
+-pedantic-errors @gol
-w -Wextra -Wall -Waddress -Waggregate-return -Warray-bounds @gol
-Wno-attributes -Wno-builtin-macro-redefined @gol
-Wc++-compat -Wc++0x-compat -Wcast-align -Wcast-qual @gol
-Wchar-subscripts -Wclobbered -Wcomment @gol
--Wconversion -Wcoverage-mismatch -Wcpp -Wno-deprecated @gol
+-Wconversion -Wcoverage-mismatch -Wno-cpp -Wno-deprecated @gol
-Wno-deprecated-declarations -Wdisabled-optimization @gol
--Wno-div-by-zero -Wempty-body -Wenum-compare -Wno-endif-labels @gol
--Werror -Werror=* @gol
+-Wno-div-by-zero -Wdouble-promotion -Wempty-body -Wenum-compare @gol
+-Wno-endif-labels -Werror -Werror=* @gol
-Wfatal-errors -Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-contains-nul -Wno-format-extra-args -Wformat-nonliteral @gol
-Wformat-security -Wformat-y2k @gol
--Wframe-larger-than=@var{len} -Wjump-misses-init -Wignored-qualifiers @gol
+-Wframe-larger-than=@var{len} -Wno-free-nonheap-object -Wjump-misses-init @gol
+-Wignored-qualifiers @gol
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int @gol
--Winit-self -Winline @gol
+-Winit-self -Winline -Wmaybe-uninitialized @gol
-Wno-int-to-pointer-cast -Wno-invalid-offsetof @gol
-Winvalid-pch -Wlarger-than=@var{len} -Wunsafe-loop-optimizations @gol
-Wlogical-op -Wlong-long @gol
--Wmain -Wmissing-braces -Wmissing-field-initializers @gol
+-Wmain -Wmaybe-uninitialized -Wmissing-braces -Wmissing-field-initializers @gol
-Wmissing-format-attribute -Wmissing-include-dirs @gol
-Wno-mudflap @gol
-Wno-multichar -Wnonnull -Wno-overflow @gol
-Wredundant-decls @gol
-Wreturn-type -Wsequence-point -Wshadow @gol
-Wsign-compare -Wsign-conversion -Wstack-protector @gol
--Wstrict-aliasing -Wstrict-aliasing=n @gol
+-Wstack-usage=@var{len} -Wstrict-aliasing -Wstrict-aliasing=n @gol
-Wstrict-overflow -Wstrict-overflow=@var{n} @gol
--Wsuggest-attribute=@r{[}const@r{|}pure@r{]} @gol
+-Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{]} @gol
-Wswitch -Wswitch-default -Wswitch-enum -Wsync-nand @gol
--Wsystem-headers -Wtrigraphs -Wtype-limits -Wundef -Wuninitialized @gol
--Wunknown-pragmas -Wno-pragmas @gol
+-Wsystem-headers -Wtrampolines -Wtrigraphs -Wtype-limits -Wundef @gol
+-Wuninitialized -Wunknown-pragmas -Wno-pragmas @gol
-Wunsuffixed-float-constants -Wunused -Wunused-function @gol
--Wunused-label -Wunused-parameter -Wno-unused-result -Wunused-value -Wunused-variable @gol
--Wunused-but-set-parameter -Wunused-but-set-variable -Wvariadic-macros -Wvla @gol
+-Wunused-label -Wunused-local-typedefs -Wunused-parameter @gol
+-Wno-unused-result -Wunused-value @gol -Wunused-variable @gol
+-Wunused-but-set-parameter -Wunused-but-set-variable @gol
+-Wvariadic-macros -Wvector-operation-performance -Wvla
-Wvolatile-register-var -Wwrite-strings}
@item C and Objective-C-only Warning Options
@xref{Debugging Options,,Options for Debugging Your Program or GCC}.
@gccoptlist{-d@var{letters} -dumpspecs -dumpmachine -dumpversion @gol
-fdbg-cnt-list -fdbg-cnt=@var{counter-value-list} @gol
+-fdisable-ipa-@var{pass_name} @gol
+-fdisable-rtl-@var{pass_name} @gol
+-fdisable-rtl-@var{pass-name}=@var{range-list} @gol
+-fdisable-tree-@var{pass_name} @gol
+-fdisable-tree-@var{pass-name}=@var{range-list} @gol
-fdump-noaddr -fdump-unnumbered -fdump-unnumbered-links @gol
-fdump-translation-unit@r{[}-@var{n}@r{]} @gol
-fdump-class-hierarchy@r{[}-@var{n}@r{]} @gol
-fdump-ipa-all -fdump-ipa-cgraph -fdump-ipa-inline @gol
+-fdump-passes @gol
-fdump-statistics @gol
-fdump-tree-all @gol
-fdump-tree-original@r{[}-@var{n}@r{]} @gol
-fcompare-debug@r{[}=@var{opts}@r{]} -fcompare-debug-second @gol
-feliminate-dwarf2-dups -feliminate-unused-debug-types @gol
-feliminate-unused-debug-symbols -femit-class-debug-always @gol
--fenable-icf-debug @gol
+-fenable-@var{kind}-@var{pass} @gol
+-fenable-@var{kind}-@var{pass}=@var{range-list} @gol
+-fdebug-types-section @gol
-fmem-report -fpre-ipa-mem-report -fpost-ipa-mem-report -fprofile-arcs @gol
-frandom-seed=@var{string} -fsched-verbose=@var{n} @gol
-fsel-sched-verbose -fsel-sched-dump-cfg -fsel-sched-pipelining-verbose @gol
--ftest-coverage -ftime-report -fvar-tracking @gol
+-fstack-usage -ftest-coverage -ftime-report -fvar-tracking @gol
-fvar-tracking-assignments -fvar-tracking-assignments-toggle @gol
-g -g@var{level} -gtoggle -gcoff -gdwarf-@var{version} @gol
--ggdb -gstabs -gstabs+ -gstrict-dwarf -gno-strict-dwarf @gol
+-ggdb -grecord-gcc-switches -gno-record-gcc-switches @gol
+-gstabs -gstabs+ -gstrict-dwarf -gno-strict-dwarf @gol
-gvms -gxcoff -gxcoff+ @gol
-fno-merge-debug-strings -fno-dwarf2-cfi-asm @gol
-fdebug-prefix-map=@var{old}=@var{new} @gol
@item Optimization Options
@xref{Optimize Options,,Options that Control Optimization}.
-@gccoptlist{
--falign-functions[=@var{n}] -falign-jumps[=@var{n}] @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 -fconserve-stack -fcprop-registers -fcrossjumping @gol
--fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules -fcx-limited-range @gol
--fdata-sections -fdce -fdce @gol
--fdelayed-branch -fdelete-null-pointer-checks -fdse -fdse @gol
--fearly-inlining -fipa-sra -fexpensive-optimizations -ffast-math @gol
--ffinite-math-only -ffloat-store -fexcess-precision=@var{style} @gol
--fforward-propagate -ffunction-sections @gol
--fgcse -fgcse-after-reload -fgcse-las -fgcse-lm @gol
+-fcheck-data-deps -fcombine-stack-adjustments -fconserve-stack @gol
+-fcompare-elim -fcprop-registers -fcrossjumping @gol
+-fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules @gol
+-fcx-limited-range @gol
+-fdata-sections -fdce -fdce -fdelayed-branch @gol
+-fdelete-null-pointer-checks -fdse -fdevirtualize -fdse @gol
+-fearly-inlining -fipa-sra -fexpensive-optimizations -ffat-lto-objects @gol
+-ffast-math -ffinite-math-only -ffloat-store -fexcess-precision=@var{style} @gol
+-fforward-propagate -ffp-contract=@var{style} -ffunction-sections @gol
+-fgcse -fgcse-after-reload -fgcse-las -fgcse-lm -fgraphite-identity @gol
-fgcse-sm -fif-conversion -fif-conversion2 -findirect-inlining @gol
-finline-functions -finline-functions-called-once -finline-limit=@var{n} @gol
--finline-small-functions -fipa-cp -fipa-cp-clone -fipa-matrix-reorg -fipa-pta @gol
--fipa-profile -fipa-pure-const -fipa-reference -fipa-struct-reorg @gol
+-finline-small-functions -fipa-cp -fipa-cp-clone -fipa-matrix-reorg @gol
+-fipa-pta -fipa-profile -fipa-pure-const -fipa-reference @gol
-fira-algorithm=@var{algorithm} @gol
--fira-region=@var{region} -fira-coalesce @gol
+-fira-region=@var{region} @gol
-fira-loop-pressure -fno-ira-share-save-slots @gol
-fno-ira-share-spill-slots -fira-verbose=@var{n} @gol
-fivopts -fkeep-inline-functions -fkeep-static-consts @gol
--floop-block -floop-interchange -floop-strip-mine -fgraphite-identity @gol
--floop-parallelize-all -flto -flto-compression-level -flto-report -fltrans @gol
--fltrans-output-list -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
+-floop-block -floop-flatten -floop-interchange -floop-strip-mine @gol
+-floop-parallelize-all -flto -flto-compression-level @gol
+-flto-partition=@var{alg} -flto-report -fmerge-all-constants @gol
+-fmerge-constants -fmodulo-sched -fmodulo-sched-allow-regmoves @gol
+-fmove-loop-invariants fmudflap -fmudflapir -fmudflapth -fno-branch-count-reg @gol
+-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
+-fpartial-inlining -fpeel-loops -fpredictive-commoning @gol
+-fprefetch-loop-arrays @gol
-fprofile-correction -fprofile-dir=@var{path} -fprofile-generate @gol
-fprofile-generate=@var{path} @gol
-fprofile-use -fprofile-use=@var{path} -fprofile-values @gol
-fschedule-insns -fschedule-insns2 -fsection-anchors @gol
-fselective-scheduling -fselective-scheduling2 @gol
-fsel-sched-pipelining -fsel-sched-pipelining-outer-loops @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 @gol
+-fshrink-wrap -fsignaling-nans -fsingle-precision-constant @gol
+-fsplit-ivs-in-unroller -fsplit-wide-types -fstack-protector @gol
+-fstack-protector-all -fstrict-aliasing -fstrict-overflow @gol
+-fthread-jumps -ftracer -ftree-bit-ccp @gol
-ftree-builtin-call-dce -ftree-ccp -ftree-ch -ftree-copy-prop @gol
--ftree-copyrename -ftree-dce @gol
--ftree-dominator-opts -ftree-dse -ftree-forwprop -ftree-fre -ftree-loop-im @gol
--ftree-phiprop -ftree-loop-distribution @gol
+-ftree-copyrename -ftree-dce -ftree-dominator-opts -ftree-dse @gol
+-ftree-forwprop -ftree-fre -ftree-loop-if-convert @gol
+-ftree-loop-if-convert-stores -ftree-loop-im @gol
+-ftree-phiprop -ftree-loop-distribution -ftree-loop-distribute-patterns @gol
-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
-ftree-parallelize-loops=@var{n} -ftree-pre -ftree-pta -ftree-reassoc @gol
--ftree-sink -ftree-sra -ftree-switch-conversion @gol
+-ftree-sink -ftree-sra -ftree-switch-conversion -ftree-tail-merge @gol
-ftree-ter -ftree-vect-loop-version -ftree-vectorize -ftree-vrp @gol
-funit-at-a-time -funroll-all-loops -funroll-loops @gol
-funsafe-loop-optimizations -funsafe-math-optimizations -funswitch-loops @gol
-fvariable-expansion-in-unroller -fvect-cost-model -fvpt -fweb @gol
--fwhole-program -fwhopr[=@var{n}] -fwpa -fuse-linker-plugin @gol
+-fwhole-program -fwpa -fuse-linker-plugin @gol
--param @var{name}=@var{value}
-O -O0 -O1 -O2 -O3 -Os -Ofast}
-iwithprefixbefore @var{dir} -isystem @var{dir} @gol
-imultilib @var{dir} -isysroot @var{dir} @gol
-M -MM -MF -MG -MP -MQ -MT -nostdinc @gol
--P -fworking-directory -remap @gol
--trigraphs -undef -U@var{macro} -Wp,@var{option} @gol
--Xpreprocessor @var{option}}
+-P -fdebug-cpp -ftrack-macro-expansion -fworking-directory @gol
+-remap -trigraphs -undef -U@var{macro} @gol
+-Wp,@var{option} -Xpreprocessor @var{option}}
@item Assembler Option
@xref{Assembler Options,,Passing Options to the Assembler}.
@item Directory Options
@xref{Directory Options,,Options for Directory Search}.
-@gccoptlist{-B@var{prefix} -I@var{dir} -iplugindir=@var{dir}}
--iquote@var{dir} -L@var{dir} -specs=@var{file} -I-
---sysroot=@var{dir}
+@gccoptlist{-B@var{prefix} -I@var{dir} -iplugindir=@var{dir} @gol
+-iquote@var{dir} -L@var{dir} -specs=@var{file} -I- @gol
+--sysroot=@var{dir}}
@item Machine Dependent Options
@xref{Submodel Options,,Hardware Models and Configurations}.
@c Try and put the significant identifier (CPU or system) first,
@c so users have a clue at guessing where the ones they want will be.
-@emph{ARC Options}
-@gccoptlist{-EB -EL @gol
--mmangle-cpu -mcpu=@var{cpu} -mtext=@var{text-section} @gol
--mdata=@var{data-section} -mrodata=@var{readonly-data-section}}
-
@emph{ARM Options}
@gccoptlist{-mapcs-frame -mno-apcs-frame @gol
-mabi=@var{name} @gol
-mapcs-reentrant -mno-apcs-reentrant @gol
-msched-prolog -mno-sched-prolog @gol
-mlittle-endian -mbig-endian -mwords-little-endian @gol
--mfloat-abi=@var{name} -msoft-float -mhard-float -mfpe @gol
+-mfloat-abi=@var{name} -mfpe @gol
-mfp16-format=@var{name}
-mthumb-interwork -mno-thumb-interwork @gol
-mcpu=@var{name} -march=@var{name} -mfpu=@var{name} @gol
-mthumb -marm @gol
-mtpcs-frame -mtpcs-leaf-frame @gol
-mcaller-super-interworking -mcallee-super-interworking @gol
--mtp=@var{name} @gol
+-mtp=@var{name} -mtls-dialect=@var{dialect} @gol
-mword-relocations @gol
-mfix-cortex-m3-ldrd}
@emph{AVR Options}
@gccoptlist{-mmcu=@var{mcu} -mno-interrupts @gol
--mcall-prologues -mtiny-stack -mint8}
+-mcall-prologues -mtiny-stack -mint8 -mstrict-X}
@emph{Blackfin Options}
@gccoptlist{-mcpu=@var{cpu}@r{[}-@var{sirevision}@r{]} @gol
-mfast-fp -minline-plt -mmulticore -mcorea -mcoreb -msdram @gol
-micplb}
+@emph{C6X Options}
+@gccoptlist{-mbig-endian -mlittle-endian -march=@var{cpu} @gol
+-msim -msdata=@var{sdata-type}}
+
@emph{CRIS Options}
@gccoptlist{-mcpu=@var{cpu} -march=@var{cpu} -mtune=@var{cpu} @gol
-mmax-stack-frame=@var{n} -melinux-stacksize=@var{n} @gol
-melf -maout -melinux -mlinux -sim -sim2 @gol
-mmul-bug-workaround -mno-mul-bug-workaround}
-@emph{CRX Options}
-@gccoptlist{-mmac -mpush-args}
-
@emph{Darwin Options}
@gccoptlist{-all_load -allowable_client -arch -arch_errors_fatal @gol
-arch_only -bind_at_load -bundle -bundle_loader @gol
-masm=@var{dialect} -mno-fancy-math-387 @gol
-mno-fp-ret-in-387 -msoft-float @gol
-mno-wide-multiply -mrtd -malign-double @gol
--mpreferred-stack-boundary=@var{num}
--mincoming-stack-boundary=@var{num}
--mcld -mcx16 -msahf -mmovbe -mcrc32 -mrecip @gol
+-mpreferred-stack-boundary=@var{num} @gol
+-mincoming-stack-boundary=@var{num} @gol
+-mcld -mcx16 -msahf -mmovbe -mcrc32 @gol
+-mrecip -mrecip=@var{opt} @gol
+-mvzeroupper @gol
-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 -mavx @gol
--maes -mpclmul -mfused-madd @gol
--msse4a -m3dnow -mpopcnt -mabm -mfma4 -mxop -mlwp @gol
--mthreads -mno-align-stringops -minline-all-stringops @gol
+-mavx2 -maes -mpclmul -mfsgsbase -mrdrnd -mf16c -mfma @gol
+-msse4a -m3dnow -mpopcnt -mabm -mbmi -mtbm -mfma4 -mxop -mlzcnt @gol
+-mbmi2 -mlwp -mthreads -mno-align-stringops -minline-all-stringops @gol
-minline-stringops-dynamically -mstringop-strategy=@var{alg} @gol
-mpush-args -maccumulate-outgoing-args -m128bit-long-double @gol
-m96bit-long-double -mregparm=@var{num} -msseregparm @gol
--mveclibabi=@var{type} -mpc32 -mpc64 -mpc80 -mstackrealign @gol
+-mveclibabi=@var{type} -mvect8-ret-in-mem @gol
+-mpc32 -mpc64 -mpc80 -mstackrealign @gol
-momit-leaf-frame-pointer -mno-red-zone -mno-tls-direct-seg-refs @gol
-mcmodel=@var{code-model} -mabi=@var{name} @gol
--m32 -m64 -mlarge-data-threshold=@var{num} @gol
--msse2avx}
+-m32 -m64 -mx32 -mlarge-data-threshold=@var{num} @gol
+-msse2avx -mfentry -m8bit-idiv @gol
+-mavx256-split-unaligned-load -mavx256-split-unaligned-store}
+
+@emph{i386 and x86-64 Windows Options}
+@gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll @gol
+-mnop-fun-dllimport -mthread @gol
+-municode -mwin32 -mwindows -fno-set-stack-executable}
@emph{IA-64 Options}
@gccoptlist{-mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic @gol
-mshared-library-id=n -mid-shared-library -mno-id-shared-library @gol
-mxgot -mno-xgot}
-@emph{M68hc1x Options}
-@gccoptlist{-m6811 -m6812 -m68hc11 -m68hc12 -m68hcs12 @gol
--mauto-incdec -minmax -mlong-calls -mshort @gol
--msoft-reg-count=@var{count}}
-
@emph{MCore Options}
@gccoptlist{-mhardlit -mno-hardlit -mdiv -mno-div -mrelax-immediates @gol
-mno-relax-immediates -mwide-bitfields -mno-wide-bitfields @gol
-mmult -mno-opts -mrepeat -ms -msatur -msdram -msim -msimnovec -mtf @gol
-mtiny=@var{n}}
+@emph{MicroBlaze Options}
+@gccoptlist{-msoft-float -mhard-float -msmall-divides -mcpu=@var{cpu} @gol
+-mmemcpy -mxl-soft-mul -mxl-soft-div -mxl-barrel-shift @gol
+-mxl-pattern-compare -mxl-stack-check -mxl-gp-opt -mno-clearbss @gol
+-mxl-multiply-high -mxl-float-convert -mxl-float-sqrt @gol
+-mxl-mode-@var{app-model}}
+
@emph{MIPS Options}
@gccoptlist{-EL -EB -march=@var{arch} -mtune=@var{arch} @gol
-mips1 -mips2 -mips3 -mips4 -mips32 -mips32r2 @gol
-mdivide-traps -mdivide-breaks @gol
-mmemcpy -mno-memcpy -mlong-calls -mno-long-calls @gol
-mmad -mno-mad -mfused-madd -mno-fused-madd -nocpp @gol
+-mfix-24k -mno-fix-24k @gol
-mfix-r4000 -mno-fix-r4000 -mfix-r4400 -mno-fix-r4400 @gol
-mfix-r10000 -mno-fix-r10000 -mfix-vr4120 -mno-fix-vr4120 @gol
-mfix-vr4130 -mno-fix-vr4130 -mfix-sb1 -mno-fix-sb1 @gol
@emph{MN10300 Options}
@gccoptlist{-mmult-bug -mno-mult-bug @gol
--mam33 -mno-am33 @gol
--mam33-2 -mno-am33-2 @gol
+-mno-am33 -mam33 -mam33-2 -mam34 @gol
+-mtune=@var{cpu-type} @gol
-mreturn-pointer-on-d0 @gol
--mno-crt0 -mrelax}
+-mno-crt0 -mrelax -mliw -msetlb}
@emph{PDP-11 Options}
@gccoptlist{-mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45 -m10 @gol
-mint16 -mno-int32 -mfloat32 -mno-float64 @gol
-mfloat64 -mno-float32 -mabshi -mno-abshi @gol
-mbranch-expensive -mbranch-cheap @gol
--msplit -mno-split -munix-asm -mdec-asm}
+-munix-asm -mdec-asm}
@emph{picoChip Options}
-@gccoptlist{-mae=@var{ae_type} -mvliw-lookahead=@var{N}
+@gccoptlist{-mae=@var{ae_type} -mvliw-lookahead=@var{N} @gol
-msymbol-as-address -mno-inefficient-warnings}
@emph{PowerPC Options}
-mstrict-align -mno-strict-align -mrelocatable @gol
-mno-relocatable -mrelocatable-lib -mno-relocatable-lib @gol
-mtoc -mno-toc -mlittle -mlittle-endian -mbig -mbig-endian @gol
--mdynamic-no-pic -maltivec -mswdiv @gol
+-mdynamic-no-pic -maltivec -mswdiv -msingle-pic-base @gol
-mprioritize-restricted-insns=@var{priority} @gol
-msched-costly-dep=@var{dependence_type} @gol
-minsert-sched-nops=@var{scheme} @gol
-mcall-sysv -mcall-netbsd @gol
-maix-struct-return -msvr4-struct-return @gol
-mabi=@var{abi-type} -msecure-plt -mbss-plt @gol
+-mblock-move-inline-limit=@var{num} @gol
-misel -mno-isel @gol
-misel=yes -misel=no @gol
-mspe -mno-spe @gol
-mprototype -mno-prototype @gol
-msim -mmvme -mads -myellowknife -memb -msdata @gol
-msdata=@var{opt} -mvxworks -G @var{num} -pthread @gol
--mrecip -mrecip=@var{opt} -mno-recip -mrecip-precision -mno-recip-precision}
+-mrecip -mrecip=@var{opt} -mno-recip -mrecip-precision @gol
+-mno-recip-precision @gol
+-mveclibabi=@var{type} -mfriz -mno-friz @gol
+-mpointers-to-nested-functions -mno-pointers-to-nested-functions @gol
+-msave-toc-indirect -mno-save-toc-indirect}
@emph{RX Options}
@gccoptlist{-m64bit-doubles -m32bit-doubles -fpu -nofpu@gol
--mcpu= -patch=@gol
+-mcpu=@gol
-mbig-endian-data -mlittle-endian-data @gol
-msmall-data @gol
-msim -mno-sim@gol
-mrelax@gol
-mmax-constant-size=@gol
-mint-register=@gol
+-mpid@gol
-msave-acc-in-interrupts}
@emph{S/390 and zSeries Options}
-madjust-unroll -mindexed-addressing -mgettrcost=@var{number} -mpt-fixed @gol
-maccumulate-outgoing-args -minvalid-symbols}
+@emph{Solaris 2 Options}
+@gccoptlist{-mimpure-text -mno-impure-text @gol
+-pthreads -pthread}
+
@emph{SPARC Options}
@gccoptlist{-mcpu=@var{cpu-type} @gol
-mtune=@var{cpu-type} @gol
-mcmodel=@var{code-model} @gol
-m32 -m64 -mapp-regs -mno-app-regs @gol
--mfaster-structs -mno-faster-structs @gol
+-mfaster-structs -mno-faster-structs -mflat -mno-flat @gol
-mfpu -mno-fpu -mhard-float -msoft-float @gol
-mhard-quad-float -msoft-quad-float @gol
--mimpure-text -mno-impure-text -mlittle-endian @gol
+-mlittle-endian @gol
-mstack-bias -mno-stack-bias @gol
-munaligned-doubles -mno-unaligned-doubles @gol
--mv8plus -mno-v8plus -mvis -mno-vis
--threads -pthreads -pthread}
+-mv8plus -mno-v8plus -mvis -mno-vis @gol
+-mvis2 -mno-vis2 -mvis3 -mno-vis3 @gol
+-mfmaf -mno-fmaf -mpopc -mno-popc @gol
+-mfix-at697f}
@emph{SPU Options}
@gccoptlist{-mwarn-reloc -merror-reloc @gol
-mtda=@var{n} -msda=@var{n} -mzda=@var{n} @gol
-mapp-regs -mno-app-regs @gol
-mdisable-callt -mno-disable-callt @gol
--mv850e1 @gol
+-mv850e2v3 @gol
+-mv850e2 @gol
+-mv850e1 -mv850es @gol
-mv850e @gol
-mv850 -mbig-switch}
@emph{x86-64 Options}
See i386 and x86-64 Options.
-@emph{i386 and x86-64 Windows Options}
-@gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll
--mnop-fun-dllimport -mthread -municode -mwin32 -mwindows
--fno-set-stack-executable}
-
@emph{Xstormy16 Options}
@gccoptlist{-msim}
-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
--fno-stack-limit @gol
+-fno-stack-limit -fsplit-stack @gol
-fleading-underscore -ftls-model=@var{model} @gol
-ftrapv -fwrapv -fbounds-check @gol
--fvisibility}
+-fvisibility -fstrict-volatile-bitfields}
@end table
@menu
Free form Fortran source code which must be preprocessed (with the
traditional preprocessor).
+@item @var{file}.go
+Go source code.
+
@c FIXME: Descriptions of Java file types.
@c @var{file}.java
@c @var{file}.class
name suffix). This option applies to all following input files until
the next @option{-x} option. Possible values for @var{language} are:
@smallexample
-c c-header c-cpp-output
+c c-header cpp-output
c++ c++-header c++-cpp-output
objective-c objective-c-header objective-c-cpp-output
objective-c++ objective-c++-header objective-c++-cpp-output
assembler assembler-with-cpp
ada
f77 f77-cpp-input f95 f95-cpp-input
+go
java
@end smallexample
the assembler is unable to read from a pipe; but the GNU assembler has
no trouble.
-@item -combine
-@opindex combine
-If you are compiling multiple source files, this option tells the driver
-to pass all the source files to the compiler at once (for those
-languages for which the compiler can handle this). This will allow
-intermodule analysis (IMA) to be performed by the compiler. Currently the only
-language for which this is supported is C@. If you pass source files for
-multiple languages to the driver, using this option, the driver will invoke
-the compiler(s) that support IMA once each, passing each compiler all the
-source files appropriate for it. For those languages that do not support
-IMA this option will be ignored, and the compiler will be invoked once for
-each source file in that language. If you use this option in conjunction
-with @option{-save-temps}, the compiler will generate multiple
-pre-processed files
-(one for each source file), but only one (combined) @file{.o} or
-@file{.s} file.
-
@item --help
@opindex help
Print (on the standard output) a description of the command line options
@item -wrapper
@opindex wrapper
-Invoke all subcommands under a wrapper program. It takes a single
-comma separated list as an argument, which will be used to invoke
-the wrapper:
+Invoke all subcommands under a wrapper program. The name of the
+wrapper program and its parameters are passed as a comma separated
+list.
@smallexample
gcc -c t.c -wrapper gdb,--args
@end smallexample
-This will invoke all subprograms of gcc under "gdb --args",
-thus cc1 invocation will be "gdb --args cc1 ...".
+This will invoke all subprograms of @command{gcc} under
+@samp{gdb --args}, thus the invocation of @command{cc1} will be
+@samp{gdb --args cc1 @dots{}}.
@item -fplugin=@var{name}.so
Load the plugin code in file @var{name}.so, assumed to be a
specs. @xref{Generating Ada Bindings for C and C++ headers,,, gnat_ugn,
GNAT User's Guide}, which provides detailed documentation on this feature.
+@item -fdump-go-spec=@var{file}
+For input files in any language, generate corresponding Go
+declarations in @var{file}. This generates Go @code{const},
+@code{type}, @code{var}, and @code{func} declarations which may be a
+useful way to start writing a Go interface to code written in some
+other language.
+
@include @value{srcdir}/../libiberty/at-file.texi
@end table
arguments followed by their declarations is also provided, inside
comments, after the declaration.
+@item -fallow-parameterless-variadic-functions
+Accept variadic functions without named parameters.
+
+Although it is possible to define such a function, this is not very
+useful as it is not possible to read the arguments. This is only
+supported for C as this construct is allowed by C++.
+
@item -fno-asm
@opindex fno-asm
Do not recognize @code{asm}, @code{inline} or @code{typeof} as a
@item -fopenmp
@opindex fopenmp
-@cindex openmp parallel
+@cindex OpenMP parallel
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
@opindex fms-extensions
Accept some non-standard constructs used in Microsoft header files.
+In C++ code, this allows member names in structures to be similar
+to previous types declarations.
+
+@smallexample
+typedef int UOW;
+struct ABC @{
+ UOW UOW;
+@};
+@end smallexample
+
Some cases of unnamed fields in structures and unions are only
accepted with this option. @xref{Unnamed Fields,,Unnamed struct/union
fields within structs/unions}, for details.
+@item -fplan9-extensions
+Accept some non-standard constructs used in Plan 9 code.
+
+This enables @option{-fms-extensions}, permits passing pointers to
+structures with anonymous fields to functions which expect pointers to
+elements of the type of the field, and permits referring to anonymous
+fields declared using a typedef. @xref{Unnamed Fields,,Unnamed
+struct/union fields within structs/unions}, for details. This is only
+supported for C, not C++.
+
@item -trigraphs
@opindex trigraphs
Support ISO C trigraphs. The @option{-ansi} option (and @option{-std}
Version 4 implements a standard mangling for vector types.
+Version 5 corrects the mangling of attribute const/volatile on
+function pointer types, decltype of a plain decl, and use of a
+function parameter in the declaration of another parameter.
+
+Version 6 corrects the promotion behavior of C++0x scoped enums.
+
See also @option{-Wabi}.
@item -fno-access-control
This option is no longer useful on most targets, now that support has
been added for putting variables into BSS without making them common.
+@item -fconstexpr-depth=@var{n}
+@opindex fconstexpr-depth
+Set the maximum nested evaluation depth for C++0x constexpr functions
+to @var{n}. A limit is needed to detect endless recursion during
+constant expression evaluation. The minimum specified by the standard
+is 512.
+
@item -fno-deduce-init-list
@opindex fno-deduce-init-list
Disable deduction of a template type parameter as
A limit on the template instantiation depth is needed to detect
endless recursions during template class instantiation. ANSI/ISO C++
conforming programs must not rely on a maximum depth greater than 17
-(changed to 1024 in C++0x).
+(changed to 1024 in C++0x). The default value is 900, as the compiler
+can run out of stack space before hitting 1024 in some situations.
@item -fno-threadsafe-statics
@opindex fno-threadsafe-statics
destructors in that class are private, and it has neither friends nor
public static member functions.
+@item -Wdelete-non-virtual-dtor @r{(C++ and Objective-C++ only)}
+@opindex Wdelete-non-virtual-dtor
+@opindex Wno-delete-non-virtual-dtor
+Warn when @samp{delete} is used to destroy an instance of a class which
+has virtual functions and non-virtual destructor. It is unsafe to delete
+an instance of a derived class through a pointer to a base class if the
+base class does not have a virtual destructor. This warning is enabled
+by @option{-Wall}.
+
+@item -Wno-narrowing @r{(C++ and Objective-C++ only)}
+@opindex Wnarrowing
+@opindex Wno-narrowing
+With -std=c++0x, suppress the diagnostic required by the standard for
+narrowing conversions within @samp{@{ @}}, e.g.
+
+@smallexample
+int i = @{ 2.2 @}; // error: narrowing from double to int
+@end smallexample
+
+This flag can be useful for compiling valid C++98 code in C++0x mode.
+
@item -Wnoexcept @r{(C++ and Objective-C++ only)}
@opindex Wnoexcept
@opindex Wno-noexcept
@item -Woverloaded-virtual @r{(C++ and Objective-C++ only)}
@opindex Woverloaded-virtual
@opindex Wno-overloaded-virtual
-@cindex overloaded virtual fn, warning
-@cindex warning for overloaded virtual fn
+@cindex overloaded virtual function, warning
+@cindex warning for overloaded virtual function
Warn when a function declaration hides virtual functions from a
base class. For example, in:
@cindex Objective-C and Objective-C++ options, command line
@cindex options, Objective-C and Objective-C++
(NOTE: This manual does not describe the Objective-C and Objective-C++
-languages themselves. See @xref{Standards,,Language Standards
+languages themselves. @xref{Standards,,Language Standards
Supported by GCC}, for references.)
This section describes the command-line options that are only meaningful
@item -fno-nil-receivers
@opindex fno-nil-receivers
-Assume that all Objective-C message dispatches (e.g.,
-@code{[receiver message:arg]}) in this translation unit ensure that the receiver
-is not @code{nil}. This allows for more efficient entry points in the runtime
-to be used. Currently, this option is only available in conjunction with
-the NeXT runtime on Mac OS X 10.3 and later.
+Assume that all Objective-C message dispatches (@code{[receiver
+message:arg]}) in this translation unit ensure that the receiver is
+not @code{nil}. This allows for more efficient entry points in the
+runtime to be used. This option is only available in conjunction with
+the NeXT runtime and ABI version 0 or 1.
+
+@item -fobjc-abi-version=@var{n}
+@opindex fobjc-abi-version
+Use version @var{n} of the Objective-C ABI for the selected runtime.
+This option is currently supported only for the NeXT runtime. In that
+case, Version 0 is the traditional (32-bit) ABI without support for
+properties and other Objective-C 2.0 additions. Version 1 is the
+traditional (32-bit) ABI with support for properties and other
+Objective-C 2.0 additions. Version 2 is the modern (64-bit) ABI. If
+nothing is specified, the default is Version 0 on 32-bit target
+machines, and Version 2 on 64-bit target machines.
@item -fobjc-call-cxx-cdtors
@opindex fobjc-call-cxx-cdtors
special @code{- (void) .cxx_destruct} method that will run
all such default destructors, in reverse order.
-The @code{- (id) .cxx_construct} and/or @code{- (void) .cxx_destruct} methods
-thusly generated will only operate on instance variables declared in the
-current Objective-C class, and not those inherited from superclasses. It
-is the responsibility of the Objective-C runtime to invoke all such methods
-in an object's inheritance hierarchy. The @code{- (id) .cxx_construct} methods
-will be invoked by the runtime immediately after a new object
-instance is allocated; the @code{- (void) .cxx_destruct} methods will
-be invoked immediately before the runtime deallocates an object instance.
+The @code{- (id) .cxx_construct} and @code{- (void) .cxx_destruct}
+methods thusly generated will only operate on instance variables
+declared in the current Objective-C class, and not those inherited
+from superclasses. It is the responsibility of the Objective-C
+runtime to invoke all such methods in an object's inheritance
+hierarchy. The @code{- (id) .cxx_construct} methods will be invoked
+by the runtime immediately after a new object instance is allocated;
+the @code{- (void) .cxx_destruct} methods will be invoked immediately
+before the runtime deallocates an object instance.
As of this writing, only the NeXT runtime on Mac OS X 10.4 and later has
support for invoking the @code{- (id) .cxx_construct} and
@item -fobjc-exceptions
@opindex fobjc-exceptions
-Enable syntactic support for structured exception handling in Objective-C,
-similar to what is offered by C++ and Java. This option is
-unavailable in conjunction with the NeXT runtime on Mac OS X 10.2 and
-earlier.
-
-@smallexample
- @@try @{
- @dots{}
- @@throw expr;
- @dots{}
- @}
- @@catch (AnObjCClass *exc) @{
- @dots{}
- @@throw expr;
- @dots{}
- @@throw;
- @dots{}
- @}
- @@catch (AnotherClass *exc) @{
- @dots{}
- @}
- @@catch (id allOthers) @{
- @dots{}
- @}
- @@finally @{
- @dots{}
- @@throw expr;
- @dots{}
- @}
-@end smallexample
-
-The @code{@@throw} statement may appear anywhere in an Objective-C or
-Objective-C++ program; when used inside of a @code{@@catch} block, the
-@code{@@throw} may appear without an argument (as shown above), in which case
-the object caught by the @code{@@catch} will be rethrown.
-
-Note that only (pointers to) Objective-C objects may be thrown and
-caught using this scheme. When an object is thrown, it will be caught
-by the nearest @code{@@catch} clause capable of handling objects of that type,
-analogously to how @code{catch} blocks work in C++ and Java. A
-@code{@@catch(id @dots{})} clause (as shown above) may also be provided to catch
-any and all Objective-C exceptions not caught by previous @code{@@catch}
-clauses (if any).
-
-The @code{@@finally} clause, if present, will be executed upon exit from the
-immediately preceding @code{@@try @dots{} @@catch} section. This will happen
-regardless of whether any exceptions are thrown, caught or rethrown
-inside the @code{@@try @dots{} @@catch} section, analogously to the behavior
-of the @code{finally} clause in Java.
-
-There are several caveats to using the new exception mechanism:
-
-@itemize @bullet
-@item
-Although currently designed to be binary compatible with @code{NS_HANDLER}-style
-idioms provided by the @code{NSException} class, the new
-exceptions can only be used on Mac OS X 10.3 (Panther) and later
-systems, due to additional functionality needed in the (NeXT) Objective-C
-runtime.
-
-@item
-As mentioned above, the new exceptions do not support handling
-types other than Objective-C objects. Furthermore, when used from
-Objective-C++, the Objective-C exception model does not interoperate with C++
-exceptions at this time. This means you cannot @code{@@throw} an exception
-from Objective-C and @code{catch} it in C++, or vice versa
-(i.e., @code{throw @dots{} @@catch}).
-@end itemize
-
-The @option{-fobjc-exceptions} switch also enables the use of synchronization
-blocks for thread-safe execution:
-
-@smallexample
- @@synchronized (ObjCClass *guard) @{
- @dots{}
- @}
-@end smallexample
-
-Upon entering the @code{@@synchronized} block, a thread of execution shall
-first check whether a lock has been placed on the corresponding @code{guard}
-object by another thread. If it has, the current thread shall wait until
-the other thread relinquishes its lock. Once @code{guard} becomes available,
-the current thread will place its own lock on it, execute the code contained in
-the @code{@@synchronized} block, and finally relinquish the lock (thereby
-making @code{guard} available to other threads).
-
-Unlike Java, Objective-C does not allow for entire methods to be marked
-@code{@@synchronized}. Note that throwing exceptions out of
-@code{@@synchronized} blocks is allowed, and will cause the guarding object
-to be unlocked properly.
+Enable syntactic support for structured exception handling in
+Objective-C, similar to what is offered by C++ and Java. This option
+is required to use the Objective-C keywords @code{@@try},
+@code{@@throw}, @code{@@catch}, @code{@@finally} and
+@code{@@synchronized}. This option is available with both the GNU
+runtime and the NeXT runtime (but not available in conjunction with
+the NeXT runtime on Mac OS X 10.2 and earlier).
@item -fobjc-gc
@opindex fobjc-gc
-Enable garbage collection (GC) in Objective-C and Objective-C++ programs.
+Enable garbage collection (GC) in Objective-C and Objective-C++
+programs. This option is only available with the NeXT runtime; the
+GNU runtime has a different garbage collection implementation that
+does not require special compiler flags.
+
+@item -fobjc-nilcheck
+@opindex fobjc-nilcheck
+For the NeXT runtime with version 2 of the ABI, check for a nil
+receiver in method invocations before doing the actual method call.
+This is the default and can be disabled using
+@option{-fno-objc-nilcheck}. Class methods and super calls are never
+checked for nil in this way no matter what this flag is set to.
+Currently this flag does nothing when the GNU runtime, or an older
+version of the NeXT runtime ABI, is used.
+
+@item -fobjc-std=objc1
+@opindex fobjc-std
+Conform to the language syntax of Objective-C 1.0, the language
+recognized by GCC 4.0. This only affects the Objective-C additions to
+the C/C++ language; it does not affect conformance to C/C++ standards,
+which is controlled by the separate C/C++ dialect option flags. When
+this option is used with the Objective-C or Objective-C++ compiler,
+any Objective-C syntax that is not recognized by GCC 4.0 is rejected.
+This is useful if you need to make sure that your Objective-C code can
+be compiled with older versions of GCC.
@item -freplace-objc-classes
@opindex freplace-objc-classes
suppresses this behavior and causes calls to @code{objc_getClass("@dots{}")}
to be retained. This is useful in Zero-Link debugging mode, since it allows
for individual class implementations to be modified during program execution.
+The GNU runtime currently always retains calls to @code{objc_get_class("@dots{}")}
+regardless of command line options.
@item -gen-decls
@opindex gen-decls
prefix) for physical lines that result from the process of breaking
a message which is too long to fit on a single line.
-@item -fdiagnostics-show-option
+@item -fno-diagnostics-show-option
+@opindex fno-diagnostics-show-option
@opindex fdiagnostics-show-option
-This option instructs the diagnostic machinery to add text to each
-diagnostic emitted, which indicates which command line option directly
-controls that diagnostic, when such an option is known to the
-diagnostic machinery.
+By default, each diagnostic emitted includes text which indicates the
+command line option that directly controls the diagnostic (if such an
+option is known to the diagnostic machinery). Specifying the
+@option{-fno-diagnostics-show-option} flag suppresses that behavior.
@item -Wcoverage-mismatch
@opindex Wcoverage-mismatch
@opindex fsyntax-only
Check the code for syntax errors, but don't do anything beyond that.
+@item -fmax-errors=@var{n}
+@opindex fmax-errors
+Limits the maximum number of error messages to @var{n}, at which point
+GCC bails out rather than attempting to continue processing the source
+code. If @var{n} is 0 (the default), there is no limit on the number
+of error messages produced. If @option{-Wfatal-errors} is also
+specified, then @option{-Wfatal-errors} takes precedence over this
+option.
+
@item -w
@opindex w
Inhibit all warning messages.
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.
+is in effect.
+
+The warning message for each controllable warning includes the
+option which controls the warning. That option can then be used with
+@option{-Werror=} and @option{-Wno-error=} as described above.
+(Printing of the option in the warning message can be disabled using the
+@option{-fno-diagnostics-show-option} flag.)
Note that specifying @option{-Werror=}@var{foo} automatically implies
@option{-W}@var{foo}. However, @option{-Wno-error=}@var{foo} does not
language-specific options also refer to @ref{C++ Dialect Options} and
@ref{Objective-C and Objective-C++ Dialect Options}.
-When an unrecognized warning label is requested (e.g.,
+When an unrecognized warning option is requested (e.g.,
@option{-Wunknown-warning}), GCC will emit a diagnostic stating
-that the option is not recognized. However, if the @samp{-Wno-} form
+that the option is not recognized. However, if the @option{-Wno-} form
is used, the behavior is slightly different: No diagnostic will be
produced for @option{-Wno-unknown-warning} unless other diagnostics
are being produced. This allows the use of new @option{-Wno-} options
-Wcomment @gol
-Wformat @gol
-Wmain @r{(only for C/ObjC and unless} @option{-ffreestanding}@r{)} @gol
+-Wmaybe-uninitialized @gol
-Wmissing-braces @gol
-Wnonnull @gol
-Wparentheses @gol
comment, or whenever a Backslash-Newline appears in a @samp{//} comment.
This warning is enabled by @option{-Wall}.
-@item -Wno-cpp \
+@item -Wno-cpp
@r{(C, Objective-C, C++, Objective-C++ and Fortran only)}
Suppress warning messages emitted by @code{#warning} directives.
+@item -Wdouble-promotion @r{(C, C++, Objective-C and Objective-C++ only)}
+@opindex Wdouble-promotion
+@opindex Wno-double-promotion
+Give a warning when a value of type @code{float} is implicitly
+promoted to @code{double}. CPUs with a 32-bit ``single-precision''
+floating-point unit implement @code{float} in hardware, but emulate
+@code{double} in software. On such a machine, doing computations
+using @code{double} values is much more expensive because of the
+overhead required for software emulation.
+
+It is easy to accidentally do computations with @code{double} because
+floating-point literals are implicitly of type @code{double}. For
+example, in:
+@smallexample
+@group
+float area(float radius)
+@{
+ return 3.14159 * radius * radius;
+@}
+@end group
+@end smallexample
+the compiler will perform the entire computation with @code{double}
+because the floating-point literal is a @code{double}.
+
@item -Wformat
@opindex Wformat
@opindex Wno-format
warning if the unused arguments are all pointers, since the Single
Unix Specification says that such unused arguments are allowed.
-@item -Wno-format-zero-length @r{(C and Objective-C only)}
+@item -Wno-format-zero-length
@opindex Wno-format-zero-length
@opindex Wformat-zero-length
If @option{-Wformat} is specified, do not warn about zero-length formats.
@option{-Wformat}. Currently equivalent to @samp{-Wformat
-Wformat-nonliteral -Wformat-security -Wformat-y2k}.
-@item -Wnonnull @r{(C and Objective-C only)}
+@item -Wnonnull
@opindex Wnonnull
@opindex Wno-nonnull
Warn about passing a null pointer for arguments marked as
@end group
@end smallexample
-Also warn for dangerous uses of the
+Also warn for dangerous uses of the
?: with omitted middle operand GNU extension. When the condition
in the ?: operator is a boolean expression the omitted value will
be always 1. Often the user expects it to be a value computed
-inside the conditional expression instead.
+inside the conditional expression instead.
This warning is enabled by @option{-Wall}.
over the precise meaning of the sequence point rules in subtle cases.
Links to discussions of the problem, including proposed formal
definitions, may be found on the GCC readings page, at
-@w{@uref{http://gcc.gnu.org/readings.html}}.
+@uref{http://gcc.gnu.org/@/readings.html}.
This warning is enabled by @option{-Wall} for C and C++.
To suppress this warning use the @samp{unused} attribute
(@pxref{Variable Attributes}).
+@item -Wunused-local-typedefs @r{(C, Objective-C, C++ and Objective-C++ only)}
+@opindex Wunused-local-typedefs
+Warn when a typedef locally defined in a function is not used.
+
@item -Wunused-parameter
@opindex Wunused-parameter
@opindex Wno-unused-parameter
computations may be deleted by data flow analysis before the warnings
are printed.
-These warnings are made optional because GCC is not smart
-enough to see all the reasons why the code might be correct
+@item -Wmaybe-uninitialized
+@opindex Wmaybe-uninitialized
+@opindex Wno-maybe-uninitialized
+For an automatic variable, if there exists a path from the function
+entry to a use of the variable that is initialized, but there exist
+some other paths the variable is not initialized, the compiler will
+emit a warning if it can not prove the uninitialized paths do not
+happen at runtime. These warnings are made optional because GCC is
+not smart enough to see all the reasons why the code might be correct
despite appearing to have an error. Here is one example of how
this can happen:
@noindent
If the value of @code{y} is always 1, 2 or 3, then @code{x} is
-always initialized, but GCC doesn't know this. Here is
-another common case:
-
-@smallexample
-@{
- int save_y;
- if (change_y) save_y = y, y = new_y;
- @dots{}
- if (change_y) y = save_y;
-@}
-@end smallexample
-
-@noindent
-This has no bug because @code{save_y} is used only if it is set.
+always initialized, but GCC doesn't know this. To suppress the
+warning, the user needs to provide a default case with assert(0) or
+similar code.
@cindex @code{longjmp} warnings
This option also warns when a non-volatile automatic variable might be
false positives.
@end table
-@item -Wsuggest-attribute=@r{[}const@r{|}pure@r{]}
+@item -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{]}
@opindex Wsuggest-attribute=
@opindex Wno-suggest-attribute=
Warn for cases where adding an attribute may be beneficial. The
@table @gcctabopt
@item -Wsuggest-attribute=pure
@itemx -Wsuggest-attribute=const
+@itemx -Wsuggest-attribute=noreturn
@opindex Wsuggest-attribute=pure
@opindex Wno-suggest-attribute=pure
@opindex Wsuggest-attribute=const
option will @emph{not} warn about unknown pragmas in system
headers---for that, @option{-Wunknown-pragmas} must also be used.
+@item -Wtrampolines
+@opindex Wtrampolines
+@opindex Wno-trampolines
+ Warn about trampolines generated for pointers to nested functions.
+
+ A trampoline is a small piece of data or code that is created at run
+ time on the stack when the address of a nested function is taken, and
+ is used to call the nested function indirectly. For some targets, it
+ is made up of data only and thus requires no special treatment. But,
+ for most targets, it is made up of code and thus requires the stack
+ to be made executable in order for the program to work properly.
+
@item -Wfloat-equal
@opindex Wfloat-equal
@opindex Wno-float-equal
@item -Wshadow
@opindex Wshadow
@opindex Wno-shadow
-Warn whenever a local variable shadows another local variable, parameter or
-global variable or whenever a built-in function is shadowed.
+Warn whenever a local variable or type declaration shadows another variable,
+parameter, type, or class member (in C++), or whenever a built-in function
+is shadowed. Note that in C++, the compiler will not warn if a local variable
+shadows a struct/class/enum, but will warn if it shadows an explicit typedef.
@item -Wlarger-than=@var{len}
@opindex Wlarger-than=@var{len}
is not included by the compiler when determining
whether or not to issue a warning.
+@item -Wno-free-nonheap-object
+@opindex Wno-free-nonheap-object
+@opindex Wfree-nonheap-object
+Do not warn when attempting to free an object which was not allocated
+on the heap.
+
+@item -Wstack-usage=@var{len}
+@opindex Wstack-usage
+Warn if the stack usage of a function might be larger than @var{len} bytes.
+The computation done to determine the stack usage is conservative.
+Any space allocated via @code{alloca}, variable-length arrays, or related
+constructs is included by the compiler when determining whether or not to
+issue a warning.
+
+The message is in keeping with the output of @option{-fstack-usage}.
+
+@itemize
+@item
+If the stack usage is fully static but exceeds the specified amount, it's:
+
+@smallexample
+ warning: stack usage is 1120 bytes
+@end smallexample
+@item
+If the stack usage is (partly) dynamic but bounded, it's:
+
+@smallexample
+ warning: stack usage might be 1648 bytes
+@end smallexample
+@item
+If the stack usage is (partly) dynamic and not bounded, it's:
+
+@smallexample
+ warning: stack usage might be unbounded
+@end smallexample
+@end itemize
+
@item -Wunsafe-loop-optimizations
@opindex Wunsafe-loop-optimizations
@opindex Wno-unsafe-loop-optimizations
alternate syntax when in pedantic ISO C99 mode. This is default.
To inhibit the warning messages, use @option{-Wno-variadic-macros}.
+@item -Wvector-operation-performance
+@opindex Wvector-operation-performance
+@opindex Wno-vector-operation-performance
+Warn if vector operation is not implemented via SIMD capabilities of the
+architecture. Mainly useful for the performance tuning.
+Vector operation can be implemented @code{piecewise} which means that the
+scalar operation is performed on every vector element;
+@code{in parallel} which means that the vector operation is implemented
+using scalars of wider type, which normally is more performance efficient;
+and @code{as a single scalar} which means that vector fits into a
+scalar type.
+
@item -Wvla
@opindex Wvla
@opindex Wno-vla
option will increase the size of debugging information by as much as a
factor of two.
+@item -fno-debug-types-section
+@opindex fno-debug-types-section
+@opindex fdebug-types-section
+By default when using DWARF v4 or higher type DIEs will be put into
+their own .debug_types section instead of making them part of the
+.debug_info section. It is more efficient to put them in a separate
+comdat sections since the linker will then be able to remove duplicates.
+But not all DWARF consumers support .debug_types sections yet.
+
@item -gstabs+
@opindex gstabs+
Produce debugging information in stabs format (if that is supported),
Version 4 may require GDB 7.0 and @option{-fvar-tracking-assignments}
for maximum benefit.
+@item -grecord-gcc-switches
+@opindex grecord-gcc-switches
+This switch causes the command line options, that were used to invoke the
+compiler and may affect code generation, to be appended to the
+DW_AT_producer attribute in DWARF debugging information. The options
+are concatenated with spaces separating them from each other and from
+the compiler version. See also @option{-frecord-gcc-switches} for another
+way of storing compiler options into the object file.
+
+@item -gno-record-gcc-switches
+@opindex gno-record-gcc-switches
+Disallow appending command line options to the DW_AT_producer attribute
+in DWARF debugging information. This is the default.
+
@item -gstrict-dwarf
@opindex gstrict-dwarf
Disallow using extensions of later DWARF standard version than selected
@option{-femit-struct-debug-reduced} and @option{-femit-struct-debug-baseonly},
which will serve for most needs.
-A specification has the syntax
+A specification has the syntax@*
[@samp{dir:}|@samp{ind:}][@samp{ord:}|@samp{gen:}](@samp{any}|@samp{sys}|@samp{base}|@samp{none})
The optional first word limits the specification to
This option works only with DWARF 2.
-@item -fenable-icf-debug
-@opindex fenable-icf-debug
-Generate additional debug information to support identical code folding (ICF).
-This option only works with DWARF version 2 or higher.
-
@item -fno-merge-debug-strings
@opindex fmerge-debug-strings
@opindex fno-merge-debug-strings
Makes the compiler print some statistics about permanent memory
allocation before or after interprocedural optimization.
+@item -fstack-usage
+@opindex fstack-usage
+Makes the compiler output stack usage information for the program, on a
+per-function basis. The filename for the dump is made by appending
+@file{.su} to the @var{auxname}. @var{auxname} 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 entry is made up
+of three fields:
+
+@itemize
+@item
+The name of the function.
+@item
+A number of bytes.
+@item
+One or more qualifiers: @code{static}, @code{dynamic}, @code{bounded}.
+@end itemize
+
+The qualifier @code{static} means that the function manipulates the stack
+statically: a fixed number of bytes are allocated for the frame on function
+entry and released on function exit; no stack adjustments are otherwise made
+in the function. The second field is this fixed number of bytes.
+
+The qualifier @code{dynamic} means that the function manipulates the stack
+dynamically: in addition to the static allocation described above, stack
+adjustments are made in the body of the function, for example to push/pop
+arguments around function calls. If the qualifier @code{bounded} is also
+present, the amount of these adjustments is bounded at compile-time and
+the second field is an upper bound of the total amount of stack used by
+the function. If it is not present, the amount of these adjustments is
+not bounded at compile-time and the second field only represents the
+bounded part.
+
@item -fprofile-arcs
@opindex fprofile-arcs
Add code so that program flow @dfn{arcs} are instrumented. During
@item -fdbg-cnt-list
@opindex fdbg-cnt-list
-Print the name and the counter upperbound for all debug counters.
+Print the name and the counter upper bound for all debug counters.
+
@item -fdbg-cnt=@var{counter-value-list}
@opindex fdbg-cnt
-Set the internal debug counter upperbound. @var{counter-value-list}
+Set the internal debug counter upper bound. @var{counter-value-list}
is a comma-separated list of @var{name}:@var{value} pairs
-which sets the upperbound of each debug counter @var{name} to @var{value}.
-All debug counters have the initial upperbound of @var{UINT_MAX},
-thus dbg_cnt() returns true always unless the upperbound is set by this option.
+which sets the upper bound of each debug counter @var{name} to @var{value}.
+All debug counters have the initial upper bound of @var{UINT_MAX},
+thus dbg_cnt() returns true always unless the upper bound is set by this option.
e.g. With -fdbg-cnt=dce:10,tail_call:0
dbg_cnt(dce) will return true only for first 10 invocations
-and dbg_cnt(tail_call) will return false always.
+
+@itemx -fenable-@var{kind}-@var{pass}
+@itemx -fdisable-@var{kind}-@var{pass}=@var{range-list}
+@opindex fdisable-
+@opindex fenable-
+
+This is a set of debugging options that are used to explicitly disable/enable
+optimization passes. For compiler users, regular options for enabling/disabling
+passes should be used instead.
+
+@itemize
+
+@item -fdisable-ipa-@var{pass}
+Disable ipa pass @var{pass}. @var{pass} is the pass name. If the same pass is
+statically invoked in the compiler multiple times, the pass name should be
+appended with a sequential number starting from 1.
+
+@item -fdisable-rtl-@var{pass}
+@item -fdisable-rtl-@var{pass}=@var{range-list}
+Disable rtl pass @var{pass}. @var{pass} is the pass name. If the same pass is
+statically invoked in the compiler multiple times, the pass name should be
+appended with a sequential number starting from 1. @var{range-list} is a comma
+seperated list of function ranges or assembler names. Each range is a number
+pair seperated by a colon. The range is inclusive in both ends. If the range
+is trivial, the number pair can be simplified as a single number. If the
+function's cgraph node's @var{uid} is falling within one of the specified ranges,
+the @var{pass} is disabled for that function. The @var{uid} is shown in the
+function header of a dump file, and the pass names can be dumped by using
+option @option{-fdump-passes}.
+
+@item -fdisable-tree-@var{pass}
+@item -fdisable-tree-@var{pass}=@var{range-list}
+Disable tree pass @var{pass}. See @option{-fdisable-rtl} for the description of
+option arguments.
+
+@item -fenable-ipa-@var{pass}
+Enable ipa pass @var{pass}. @var{pass} is the pass name. If the same pass is
+statically invoked in the compiler multiple times, the pass name should be
+appended with a sequential number starting from 1.
+
+@item -fenable-rtl-@var{pass}
+@item -fenable-rtl-@var{pass}=@var{range-list}
+Enable rtl pass @var{pass}. See @option{-fdisable-rtl} for option argument
+description and examples.
+
+@item -fenable-tree-@var{pass}
+@item -fenable-tree-@var{pass}=@var{range-list}
+Enable tree pass @var{pass}. See @option{-fdisable-rtl} for the description
+of option arguments.
+
+@smallexample
+
+# disable ccp1 for all functions
+ -fdisable-tree-ccp1
+# disable complete unroll for function whose cgraph node uid is 1
+ -fenable-tree-cunroll=1
+# disable gcse2 for functions at the following ranges [1,1],
+# [300,400], and [400,1000]
+# disable gcse2 for functions foo and foo2
+ -fdisable-rtl-gcse2=foo,foo2
+# disable early inlining
+ -fdisable-tree-einline
+# disable ipa inlining
+ -fdisable-ipa-inline
+# enable tree full unroll
+ -fenable-tree-unroll
+
+@end smallexample
+
+@end itemize
@item -d@var{letters}
@itemx -fdump-rtl-@var{pass}
@var{letters}. This is used for debugging the RTL-based passes of the
compiler. The file names for most of the dumps are made by appending
a pass number and a word to the @var{dumpname}, and the files are
-created in the directory of the output file. @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. These switches may have different effects when
-@option{-E} is used for preprocessing.
+created in the directory of the output file. Note that the pass
+number is computed statically as passes get registered into the pass
+manager. Thus the numbering is not related to the dynamic order of
+execution of passes. In particular, a pass installed by a plugin
+could have a number over 200 even if it executed quite early.
+@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. These switches may have different effects
+when @option{-E} is used for preprocessing.
Debug dumps can be enabled with a @option{-fdump-rtl} switch or some
@option{-d} option @var{letters}. Here are the possible
@opindex dx
Just generate RTL for a function instead of compiling it. Usually used
with @option{-fdump-rtl-expand}.
-
-@item -dy
-@opindex dy
-Dump debugging information during parsing, to standard error.
@end table
@item -fdump-noaddr
@end table
+@item -fdump-passes
+@opindex fdump-passes
+Dump the list of optimization passes that are turned on and off by
+the current command line options.
+
@item -fdump-statistics-@var{option}
@opindex fdump-statistics
Enable and control dumping of pass statistics in a separate file. The
Enable showing the tree dump for each statement.
@item eh
Enable showing the EH region number holding each statement.
+@item scev
+Enable showing scalar evolution analysis details.
@item all
Turn on all options, except @option{raw}, @option{slim}, @option{verbose}
and @option{lineno}.
optimizations that have a flag are listed in this section.
Most optimizations are only enabled if an @option{-O} level is set on
-the command line. Otherwise they are disabled, even if individual
+the command line. Otherwise they are disabled, even if individual
optimization flags are specified.
Depending on the target and how GCC was configured, a slightly different
@option{-O} turns on the following optimization flags:
@gccoptlist{
-fauto-inc-dec @gol
+-fcompare-elim @gol
-fcprop-registers @gol
-fdce @gol
-fdefer-pop @gol
-fipa-reference @gol
-fmerge-constants
-fsplit-wide-types @gol
+-ftree-bit-ccp @gol
-ftree-builtin-call-dce @gol
-ftree-ccp @gol
-ftree-ch @gol
-fcrossjumping @gol
-fcse-follow-jumps -fcse-skip-blocks @gol
-fdelete-null-pointer-checks @gol
+-fdevirtualize @gol
-fexpensive-optimizations @gol
-fgcse -fgcse-lm @gol
-finline-small-functions @gol
-findirect-inlining @gol
-fipa-sra @gol
-foptimize-sibling-calls @gol
+-fpartial-inlining @gol
-fpeephole2 @gol
-fregmove @gol
-freorder-blocks -freorder-functions @gol
-fsched-interblock -fsched-spec @gol
-fschedule-insns -fschedule-insns2 @gol
-fstrict-aliasing -fstrict-overflow @gol
--ftree-switch-conversion @gol
+-ftree-switch-conversion -ftree-tail-merge @gol
-ftree-pre @gol
-ftree-vrp}
Optimize yet more. @option{-O3} turns on all optimizations specified
by @option{-O2} and also turns on the @option{-finline-functions},
@option{-funswitch-loops}, @option{-fpredictive-commoning},
-@option{-fgcse-after-reload} and @option{-ftree-vectorize} options.
+@option{-fgcse-after-reload}, @option{-ftree-vectorize} and
+@option{-fipa-cp-clone} options.
@item -O0
@opindex O0
Disregard strict standards compliance. @option{-Ofast} enables all
@option{-O3} optimizations. It also enables optimizations that are not
valid for all standard compliant programs.
-It turns on @option{-ffast-math}.
+It turns on @option{-ffast-math} and the Fortran-specific
+@option{-fno-protect-parens} and @option{-fstack-arrays}.
If you use multiple @option{-O} options, with or without level numbers,
the last such option is the one that is effective.
This option is enabled by default at optimization levels @option{-O},
@option{-O2}, @option{-O3}, @option{-Os}.
+@item -ffp-contract=@var{style}
+@opindex ffp-contract
+@option{-ffp-contract=off} disables floating-point expression contraction.
+@option{-ffp-contract=fast} enables floating-point expression contraction
+such as forming of fused multiply-add operations if the target has
+native support for them.
+@option{-ffp-contract=on} enables floating-point expression contraction
+if allowed by the language standard. This is currently not implemented
+and treated equal to @option{-ffp-contract=off}.
+
+The default is @option{-ffp-contract=fast}.
+
@item -fomit-frame-pointer
@opindex fomit-frame-pointer
Don't keep the frame pointer in a register for functions that
whether a target machine supports this flag. @xref{Registers,,Register
Usage, gccint, GNU Compiler Collection (GCC) Internals}.
+Starting with GCC version 4.6, the default setting (when not optimizing for
+size) for 32-bit Linux x86 and 32-bit Darwin x86 targets has been changed to
+@option{-fomit-frame-pointer}. The default can be reverted to
+@option{-fno-omit-frame-pointer} by configuring GCC with the
+@option{--enable-frame-pointer} configure option.
+
Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -foptimize-sibling-calls
of assembly instructions and as such its exact meaning might change from one
release to an another.
+@item -fno-keep-inline-dllexport
+@opindex -fno-keep-inline-dllexport
+This is a more fine-grained version of @option{-fkeep-inline-functions},
+which applies only to functions that are declared using the @code{dllexport}
+attribute or declspec (@xref{Function Attributes,,Declaring Attributes of
+Functions}.)
+
@item -fkeep-inline-functions
@opindex fkeep-inline-functions
In C, emit @code{static} functions that are declared @code{inline}
@option{-O2}, @option{-O3}, @option{-Os}. Passes that use the information
are enabled independently at different optimization levels.
+@item -fdevirtualize
+@opindex fdevirtualize
+Attempt to convert calls to virtual functions to direct calls. This
+is done both within a procedure and interprocedurally as part of
+indirect inlining (@code{-findirect-inlining}) and interprocedural constant
+propagation (@option{-fipa-cp}).
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+
@item -fexpensive-optimizations
@opindex fexpensive-optimizations
Perform a number of minor optimizations that are relatively expensive.
decent code and the smallest size code, and the default value usually
give the best results in most cases and for most architectures.
-@item -fira-coalesce
-@opindex fira-coalesce
-Do optimistic register coalescing. This option might be profitable for
-architectures with big regular register files.
-
@item -fira-loop-pressure
@opindex fira-loop-pressure
Use IRA to evaluate register pressure in loops for decision to move
@item -fsched-group-heuristic
@opindex fsched-group-heuristic
-Enable the group heuristic in the scheduler. This heuristic favors
-the instruction that belongs to a schedule group. This is enabled
-by default when scheduling is enabled, i.e.@: with @option{-fschedule-insns}
+Enable the group heuristic in the scheduler. This heuristic favors
+the instruction that belongs to a schedule group. This is enabled
+by default when scheduling is enabled, i.e.@: with @option{-fschedule-insns}
or @option{-fschedule-insns2} or at @option{-O2} or higher.
@item -fsched-critical-path-heuristic
@opindex fsched-critical-path-heuristic
-Enable the critical-path heuristic in the scheduler. This heuristic favors
-instructions on the critical path. This is enabled by default when
-scheduling is enabled, i.e.@: with @option{-fschedule-insns}
+Enable the critical-path heuristic in the scheduler. This heuristic favors
+instructions on the critical path. This is enabled by default when
+scheduling is enabled, i.e.@: with @option{-fschedule-insns}
or @option{-fschedule-insns2} or at @option{-O2} or higher.
@item -fsched-spec-insn-heuristic
@opindex fsched-spec-insn-heuristic
-Enable the speculative instruction heuristic in the scheduler. This
-heuristic favors speculative instructions with greater dependency weakness.
-This is enabled by default when scheduling is enabled, i.e.@:
-with @option{-fschedule-insns} or @option{-fschedule-insns2}
+Enable the speculative instruction heuristic in the scheduler. This
+heuristic favors speculative instructions with greater dependency weakness.
+This is enabled by default when scheduling is enabled, i.e.@:
+with @option{-fschedule-insns} or @option{-fschedule-insns2}
or at @option{-O2} or higher.
@item -fsched-rank-heuristic
@opindex fsched-rank-heuristic
-Enable the rank heuristic in the scheduler. This heuristic favors
-the instruction belonging to a basic block with greater size or frequency.
-This is enabled by default when scheduling is enabled, i.e.@:
-with @option{-fschedule-insns} or @option{-fschedule-insns2} or
+Enable the rank heuristic in the scheduler. This heuristic favors
+the instruction belonging to a basic block with greater size or frequency.
+This is enabled by default when scheduling is enabled, i.e.@:
+with @option{-fschedule-insns} or @option{-fschedule-insns2} or
at @option{-O2} or higher.
@item -fsched-last-insn-heuristic
@opindex fsched-last-insn-heuristic
-Enable the last-instruction heuristic in the scheduler. This heuristic
+Enable the last-instruction heuristic in the scheduler. This heuristic
favors the instruction that is less dependent on the last instruction
-scheduled. This is enabled by default when scheduling is enabled,
-i.e.@: with @option{-fschedule-insns} or @option{-fschedule-insns2} or
+scheduled. This is enabled by default when scheduling is enabled,
+i.e.@: with @option{-fschedule-insns} or @option{-fschedule-insns2} or
at @option{-O2} or higher.
@item -fsched-dep-count-heuristic
@opindex fsched-dep-count-heuristic
-Enable the dependent-count heuristic in the scheduler. This heuristic
-favors the instruction that has more instructions depending on it.
-This is enabled by default when scheduling is enabled, i.e.@:
-with @option{-fschedule-insns} or @option{-fschedule-insns2} or
+Enable the dependent-count heuristic in the scheduler. This heuristic
+favors the instruction that has more instructions depending on it.
+This is enabled by default when scheduling is enabled, i.e.@:
+with @option{-fschedule-insns} or @option{-fschedule-insns2} or
at @option{-O2} or higher.
@item -freschedule-modulo-scheduled-loops
When pipelining loops during selective scheduling, also pipeline outer loops.
This option has no effect until @option{-fsel-sched-pipelining} is turned on.
+@item -fshrink-wrap
+@opindex fshrink-wrap
+Emit function prologues only before parts of the function that need it,
+rather than at the top of the function. This flag is enabled by default at
+@option{-O} and higher.
+
@item -fcaller-saves
@opindex fcaller-saves
Enable values to be allocated in registers that will be clobbered by
Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
+@item -fcombine-stack-adjustments
+@opindex fcombine-stack-adjustments
+Tracks stack adjustments (pushes and pops) and stack memory references
+and then tries to find ways to combine them.
+
+Enabled by default at @option{-O1} and higher.
+
@item -fconserve-stack
@opindex fconserve-stack
Attempt to minimize stack usage. The compiler will attempt to use less
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). 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 and interprocedural modification
Perform forward store motion on trees. This flag is
enabled by default at @option{-O} and higher.
+@item -ftree-bit-ccp
+@opindex ftree-bit-ccp
+Perform sparse conditional bit constant propagation on trees and propagate
+pointer alignment information.
+This pass only operates on local scalar variables and is enabled by default
+at @option{-O} and higher. It requires that @option{-ftree-ccp} is enabled.
+
@item -ftree-ccp
@opindex ftree-ccp
Perform sparse conditional constant propagation (CCP) on trees. This
initializations from a scalar array. This flag is enabled by default
at @option{-O2} and higher.
+@item -ftree-tail-merge
+Look for identical code sequences. When found, replace one with a jump to the
+other. This optimization is known as tail merging or cross jumping. This flag
+is enabled by default at @option{-O2} and higher. The run time of this pass can
+be limited using @option{max-tail-merge-comparisons} parameter and
+@option{max-tail-merge-iterations} parameter.
+
@item -ftree-dce
@opindex ftree-dce
Perform dead code elimination (DCE) on trees. This flag is enabled by
@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.
+Perform loop interchange transformations on tree. Same as
+@option{-floop-interchange}. To use this code transformation, GCC has
+to be configured with @option{--with-ppl} and @option{--with-cloog} to
+enable the Graphite loop transformation infrastructure.
@item -floop-interchange
+@opindex floop-interchange
Perform loop interchange transformations on loops. Interchanging two
nested loops switches the inner and outer loops. For example, given a
loop like:
Graphite loop transformation infrastructure.
@item -floop-strip-mine
+@opindex floop-strip-mine
Perform loop strip mining transformations on loops. Strip mining
splits a loop into two nested loops. The outer loop has strides
equal to the strip size and the inner loop has strides of the
enable the Graphite loop transformation infrastructure.
@item -floop-block
+@opindex floop-block
Perform loop blocking transformations on loops. Blocking strip mines
each loop in the loop nest such that the memory accesses of the
element loops fit inside caches. The strip length can be changed
are also performed by the code generator CLooG, like index splitting and
dead code elimination in loops.
+@item -floop-flatten
+@opindex floop-flatten
+Removes the loop nesting structure: transforms the loop nest into a
+single loop. This transformation can be useful to vectorize all the
+levels of the loop nest.
+
@item -floop-parallelize-all
+@opindex floop-parallelize-all
Use the Graphite data dependence analysis to identify loops that can
be parallelized. Parallelize all the loops that can be analyzed to
not contain loop carried dependences without checking that it is
Compare the results of several data dependence analyzers. This option
is used for debugging the data dependence analyzers.
+@item -ftree-loop-if-convert
+Attempt to transform conditional jumps in the innermost loops to
+branch-less equivalents. The intent is to remove control-flow from
+the innermost loops in order to improve the ability of the
+vectorization pass to handle these loops. This is enabled by default
+if vectorization is enabled.
+
+@item -ftree-loop-if-convert-stores
+Attempt to also if-convert conditional jumps containing memory writes.
+This transformation can be unsafe for multi-threaded programs as it
+transforms conditional memory writes into unconditional memory writes.
+For example,
+@smallexample
+for (i = 0; i < N; i++)
+ if (cond)
+ A[i] = expr;
+@end smallexample
+would be transformed to
+@smallexample
+for (i = 0; i < N; i++)
+ A[i] = cond ? expr : A[i];
+@end smallexample
+potentially producing data races.
+
@item -ftree-loop-distribution
Perform loop distribution. This flag can improve cache performance on
big loop bodies and allow further loop optimizations, like
ENDDO
@end smallexample
+@item -ftree-loop-distribute-patterns
+Perform loop distribution of patterns that can be code generated with
+calls to a library. This flag is enabled by default at @option{-O3}.
+
+This pass distributes the initialization loops and generates a call to
+memset zero. For example, the loop
+@smallexample
+DO I = 1, N
+ A(I) = 0
+ B(I) = A(I) + I
+ENDDO
+@end smallexample
+is transformed to
+@smallexample
+DO I = 1, N
+ A(I) = 0
+ENDDO
+DO I = 1, N
+ B(I) = A(I) + I
+ENDDO
+@end smallexample
+and the initialization loop is transformed into a call to memset zero.
+
@item -ftree-loop-im
@opindex ftree-loop-im
Perform loop invariant motion on trees. This pass moves only invariants that
With this option, the compiler will create multiple copies of some
local variables when unrolling a loop which can result in superior code.
+@item -fpartial-inlining
+@opindex fpartial-inlining
+Inline parts of functions. This option has any effect only
+when inlining itself is turned on by the @option{-finline-functions}
+or @option{-finline-small-functions} options.
+
+Enabled at level @option{-O2}.
+
@item -fpredictive-commoning
@opindex fpredictive-commoning
Perform predictive commoning optimization, i.e., reusing computations
Assume that the current compilation unit represents the whole program being
compiled. All public functions and variables with the exception of @code{main}
and those merged by attribute @code{externally_visible} become static functions
-and in effect are optimized more aggressively by interprocedural optimizers.
+and in effect are optimized more aggressively by interprocedural optimizers. If @command{gold} is used as the linker plugin, @code{externally_visible} attributes are automatically added to functions (not variable yet due to a current @command{gold} issue) that are accessed outside of LTO objects according to resolution file produced by @command{gold}. For other linkers that cannot generate resolution file, explicit @code{externally_visible} attributes are still necessary.
While this option is equivalent to proper use of the @code{static} keyword for
programs consisting of a single file, in combination with option
-@option{-combine}, @option{-flto} or @option{-fwhopr} this flag can be used to
+@option{-flto} this flag can be used to
compile many smaller scale programs since the functions and variables become
local for the whole combined compilation unit, not for the single source file
itself.
This option implies @option{-fwhole-file} for Fortran programs.
-@item -flto
+@item -flto[=@var{n}]
@opindex flto
This option runs the standard link-time optimizer. When invoked
with source code, it generates GIMPLE (one of GCC's internal
optimizations the @option{-flto} flag needs to be passed to both the
compile and the link commands.
+To make whole program optimization effective, it is necessary to make
+certain whole program assumptions. The compiler needs to know
+what functions and variables can be accessed by libraries and runtime
+outside of the link time optimized unit. When supported by the linker,
+the linker plugin (see @option{-fuse-linker-plugin}) passes to the
+compiler information about used and externally visible symbols. When
+the linker plugin is not available, @option{-fwhole-program} should be
+used to allow the compiler to make these assumptions, which will lead
+to more aggressive optimization decisions.
+
Note that when a file is compiled with @option{-flto}, the generated
object file will be larger than a regular object file because it will
contain GIMPLE bytecodes and the usual final code. This means that
behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be
issued. The behavior is still undefined at runtime.
-If object files containing GIMPLE bytecode are stored in a library
-archive, say @file{libfoo.a}, it is possible to extract and use them
-in an LTO link if you are using @command{gold} as the linker (which,
-in turn requires GCC to be configured with @option{--enable-gold}).
-To enable this feature, use the flag @option{-fuse-linker-plugin} at
-link-time:
+If object files containing GIMPLE bytecode are stored in a library archive, say
+@file{libfoo.a}, it is possible to extract and use them in an LTO link if you
+are using a linker with linker plugin support. To enable this feature, use
+the flag @option{-fuse-linker-plugin} at link-time:
@smallexample
gcc -o myprog -O2 -flto -fuse-linker-plugin a.o b.o -lfoo
@end smallexample
-With the linker plugin enabled, @command{gold} will extract the needed
+With the linker plugin enabled, the linker will extract the needed
GIMPLE files from @file{libfoo.a} and pass them on to the running GCC
to make them part of the aggregated GIMPLE image to be optimized.
-If you are not using @command{gold} and/or do not specify
-@option{-fuse-linker-plugin} then the objects inside @file{libfoo.a}
+If you are not using a linker with linker plugin support and/or do not
+enable linker plugin then the objects inside @file{libfoo.a}
will be extracted and linked as usual, but they will not participate
in the LTO optimization process.
-Link time optimizations do not require the presence of the whole
-program to operate. If the program does not require any symbols to
-be exported, it is possible to combine @option{-flto} and
-@option{-fwhopr} with @option{-fwhole-program} to allow the
-interprocedural optimizers to use more aggressive assumptions which
-may lead to improved optimization opportunities.
+Link time optimizations do not require the presence of the whole program to
+operate. If the program does not require any symbols to be exported, it is
+possible to combine @option{-flto} and with @option{-fwhole-program} to allow
+the interprocedural optimizers to use more aggressive assumptions which may
+lead to improved optimization opportunities.
+Use of @option{-fwhole-program} is not needed when linker plugin is
+active (see @option{-fuse-linker-plugin}).
Regarding portability: the current implementation of LTO makes no
attempt at generating bytecode that can be ported between different
GCC will not work with an older/newer version of GCC.
Link time optimization does not play well with generating debugging
-information. Combining @option{-flto} or @option{-fwhopr} with
-@option{-g} is experimental.
+information. Combining @option{-flto} with
+@option{-g} is currently experimental and expected to produce wrong
+results.
+
+If you specify the optional @var{n}, the optimization and code
+generation done at link time is executed in parallel using @var{n}
+parallel jobs by utilizing an installed @command{make} program. The
+environment variable @env{MAKE} may be used to override the program
+used. The default value for @var{n} is 1.
+
+You can also specify @option{-flto=jobserver} to use GNU make's
+job server mode to determine the number of parallel jobs. This
+is useful when the Makefile calling GCC is already executing in parallel.
+The parent Makefile will need a @samp{+} prepended to the command recipe
+for this to work. This will likely only work if @env{MAKE} is
+GNU make.
This option is disabled by default.
-@item -fwhopr[=@var{n}]
-@opindex fwhopr
-This option is identical in functionality to @option{-flto} but it
-differs in how the final link stage is executed. Instead of loading
-all the function bodies in memory, the callgraph is analyzed and
-optimization decisions are made (whole program analysis or WPA). Once
-optimization decisions are made, the callgraph is partitioned and the
-different sections are compiled separately (local transformations or
-LTRANS)@. This process allows optimizations on very large programs
-that otherwise would not fit in memory. This option enables
-@option{-fwpa} and @option{-fltrans} automatically.
-
-If you specify the optional @var{n} the link stage is executed in
-parallel using @var{n} parallel jobs by utilizing an installed
-@command{make} program. The environment variable @env{MAKE} may be
-used to override the program used.
-
-Disabled by default.
-
-@item -fwpa
-@opindex fwpa
-This is an internal option used by GCC when compiling with
-@option{-fwhopr}. You should never need to use it.
-
-This option runs the link-time optimizer in the whole-program-analysis
-(WPA) mode, which reads in summary information from all inputs and
-performs a whole-program analysis based on summary information only.
-It generates object files for subsequent runs of the link-time
-optimizer where individual object files are optimized using both
-summary information from the WPA mode and the actual function bodies.
-It then drives the LTRANS phase.
-
-Disabled by default.
-
-@item -fltrans
-@opindex fltrans
-This is an internal option used by GCC when compiling with
-@option{-fwhopr}. You should never need to use it.
-
-This option runs the link-time optimizer in the local-transformation (LTRANS)
-mode, which reads in output from a previous run of the LTO in WPA mode.
-In the LTRANS mode, LTO optimizes an object and produces the final assembly.
-
-Disabled by default.
-
-@item -fltrans-output-list=@var{file}
-@opindex fltrans-output-list
-This is an internal option used by GCC when compiling with
-@option{-fwhopr}. You should never need to use it.
-
-This option specifies a file to which the names of LTRANS output files are
-written. This option is only meaningful in conjunction with @option{-fwpa}.
-
-Disabled by default.
+@item -flto-partition=@var{alg}
+@opindex flto-partition
+Specify the partitioning algorithm used by the link time optimizer.
+The value is either @code{1to1} to specify a partitioning mirroring
+the original source files or @code{balanced} to specify partitioning
+into equally sized chunks (whenever possible). Specifying @code{none}
+as an algorithm disables partitioning and streaming completely. The
+default value is @code{balanced}.
@item -flto-compression-level=@var{n}
This option specifies the level of compression used for intermediate
language written to LTO object files, and is only meaningful in
-conjunction with LTO mode (@option{-fwhopr}, @option{-flto}). Valid
+conjunction with LTO mode (@option{-flto}). Valid
values are 0 (no compression) to 9 (maximum compression). Values
outside this range are clamped to either 0 or 9. If the option is not
given, a default balanced compression setting is used.
Prints a report with internal details on the workings of the link-time
optimizer. The contents of this report vary from version to version,
it is meant to be useful to GCC developers when processing object
-files in LTO mode (via @option{-fwhopr} or @option{-flto}).
+files in LTO mode (via @option{-flto}).
Disabled by default.
@item -fuse-linker-plugin
-Enables the extraction of objects with GIMPLE bytecode information
-from library archives. This option relies on features available only
-in @command{gold}, so to use this you must configure GCC with
-@option{--enable-gold}. See @option{-flto} for a description on the
-effect of this flag and how to use it.
+Enables the use of a linker plugin during link time optimization. This
+option relies on plugin support in the linker, which is available in gold
+or in GNU ld 2.21 or newer.
+
+This option enables the extraction of object files with GIMPLE bytecode out
+of library archives. This improves the quality of optimization by exposing
+more code to the link time optimizer. This information specifies what
+symbols can be accessed externally (by non-LTO object or during dynamic
+linking). Resulting code quality improvements on binaries (and shared
+libraries that use hidden visibility) are similar to @code{-fwhole-program}.
+See @option{-flto} for a description of the effect of this flag and how to
+use it.
+
+Enabled by default when LTO support in GCC is enabled and GCC was compiled
+with a linker supporting plugins (GNU ld 2.21 or newer or gold).
+
+@item -ffat-lto-objects
+@opindex ffat-lto-objects
+Fat LTO objects are object files that contain both the intermediate language
+and the object code. This makes them useable for both LTO linking and normal
+linking. This option makes effect only with @option{-flto} and is ignored
+at linktime.
+
+@option{-fno-fat-lto-objects} improves compilation time over plain LTO, but
+requires the complete toolchain to be aware of LTO. It requires a linker with
+linker plugin support for basic functionality. Additionally, nm, ar and ranlib
+need to support linker plugins to allow a full-featured build environment
+(capable of building static libraries etc).
+
+The default is @option{-ffat-lto-objects} but this default is intended to
+change in future releases when linker plugin enabled environments become more
+common.
+@item -fcompare-elim
+@opindex fcompare-elim
+After register allocation and post-register allocation instruction splitting,
+identify arithmetic instructions that compute processor flags similar to a
+comparison operation based on that arithmetic. If possible, eliminate the
+explicit comparison operation.
-Disabled by default.
+This pass only applies to certain targets that cannot explicitly represent
+the comparison operation before register allocation is complete.
+
+Enabled at levels @option{-O}, @option{-O2}, @option{-O3}, @option{-Os}.
@item -fcprop-registers
@opindex fcprop-registers
@item -fprofile-dir=@var{path}
@opindex fprofile-dir
-Set the directory to search the profile data files in to @var{path}.
+Set the directory to search for the profile data files in to @var{path}.
This option affects only the profile data generated by
@option{-fprofile-generate}, @option{-ftest-coverage}, @option{-fprofile-arcs}
and used by @option{-fprofile-use} and @option{-fbranch-probabilities}
-and its related options.
-By default, GCC will use the current directory as @var{path}
-thus the profile data file will appear in the same directory as the object file.
+and its related options. Both absolute and relative paths can be used.
+By default, GCC will use the current directory as @var{path}, thus the
+profile data file will appear in the same directory as the object file.
@item -fprofile-generate
@itemx -fprofile-generate=@var{path}
This option causes the preprocessor macro @code{__FAST_MATH__} to be defined.
-This option is not 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 for
-math functions. It may, however, yield faster code for programs
+This option is not turned on by any @option{-O} option besides
+@option{-Ofast} since it can result in incorrect output for programs
+which depend on 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.
@item -fno-math-errno
@samp{REG_BR_PROB} note on each @samp{JUMP_INSN} and @samp{CALL_INSN}.
These can be used to improve optimization. Currently, they are only
used in one place: in @file{reorg.c}, instead of guessing which path a
-branch is mostly to take, the @samp{REG_BR_PROB} values are used to
+branch is most likely to take, the @samp{REG_BR_PROB} values are used to
exactly determine which path is taken more often.
@item -fprofile-values
data about values of expressions in the program is gathered.
With @option{-fbranch-probabilities}, it reads back the data gathered
-from profiling values of expressions and adds @samp{REG_VALUE_PROFILE}
-notes to instructions for their later usage in optimizations.
+from profiling values of expressions for usage in optimizations.
Enabled with @option{-fprofile-generate} and @option{-fprofile-use}.
@var{name} are given in the following table:
@table @gcctabopt
-@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 predictable-branch-outcome
When branch is predicted to be taken with probability lower than this threshold
(in percent), then it is considered well predictable. The default is 10.
optimization. If more memory than specified is required, the
optimization will not be done.
+@item max-gcse-insertion-ratio
+If the ratio of expression insertions to deletions is larger than this value
+for any expression, then RTL PRE will insert or remove the expression and thus
+leave partially redundant computations in the instruction stream. The default value is 20.
+
@item max-pending-list-length
The maximum number of pending dependencies scheduling will allow
before flushing the current state and starting over. Large functions
with few branches or calls can create excessively large lists which
needlessly consume memory and resources.
+@item max-modulo-backtrack-attempts
+The maximum number of backtrack attempts the scheduler should make
+when modulo scheduling a loop. Larger values can exponentially increase
+compile time.
+
@item max-inline-insns-single
Several parameters control the tree inliner used in gcc.
This number sets the maximum number of instructions (counted in GCC's
internal representation) in a single function that the tree inliner
will consider for inlining. This only affects functions declared
inline and methods implemented in a class declaration (C++).
-The default value is 300.
+The default value is 400.
@item max-inline-insns-auto
When you use @option{-finline-functions} (included in @option{-O3}),
by the compiler will be investigated. To those functions, a different
(more restrictive) limit compared to functions declared inline can
be applied.
-The default value is 50.
+The default value is 40.
@item large-function-insns
The limit specifying really large functions. For functions larger than this
@item early-inlining-insns
Specify growth that early inliner can make. In effect it increases amount of
-inlining for code having large abstraction penalty. The default value is 8.
+inlining for code having large abstraction penalty. The default value is 10.
@item max-early-inliner-iterations
@itemx max-early-inliner-iterations
indirect calls early inliner can resolve. Deeper chains are still handled by
late inlining.
+@item comdat-sharing-probability
+@itemx comdat-sharing-probability
+Probability (in percent) that C++ inline function with comdat visibility
+will be shared across multiple compilation units. The default value is 20.
+
@item min-vect-loop-bound
The minimum number of iterations under which a loop will not get vectorized
when @option{-ftree-vectorize} is used. The number of iterations after
vectorization needs to be greater than the value specified by this option
to allow vectorization. The default value is 0.
+@item gcse-cost-distance-ratio
+Scaling factor in calculation of maximum distance an expression
+can be moved by GCSE optimizations. This is currently supported only in the
+code hoisting pass. The bigger the ratio, the more aggressive code hoisting
+will be with simple expressions, i.e., the expressions which have cost
+less than @option{gcse-unrestricted-cost}. Specifying 0 will disable
+hoisting of simple expressions. The default value is 10.
+
+@item gcse-unrestricted-cost
+Cost, roughly measured as the cost of a single typical machine
+instruction, at which GCSE optimizations will not constrain
+the distance an expression can travel. This is currently
+supported only in the code hoisting pass. The lesser the cost,
+the more aggressive code hoisting will be. Specifying 0 will
+allow all expressions to travel unrestricted distances.
+The default value is 3.
+
+@item max-hoist-depth
+The depth of search in the dominator tree for expressions to hoist.
+This is used to avoid quadratic behavior in hoisting algorithm.
+The value of 0 will avoid limiting the search, but may slow down compilation
+of huge functions. The default value is 30.
+
+@item max-tail-merge-comparisons
+The maximum amount of similar bbs to compare a bb with. This is used to
+avoid quadratic behaviour in tree tail merging. The default value is 10.
+
+@item max-tail-merge-iterations
+The maximum amount of iterations of the pass over the function. This is used to
+limit run time in tree tail merging. The default value is 2.
+
@item max-unrolled-insns
The maximum number of instructions that a loop should have if that loop
is unrolled, and if the loop is unrolled, it determines how many times
Bound on size of expressions used in the scalar evolutions analyzer.
Large expressions slow the analyzer.
+@item scev-max-expr-complexity
+Bound on the complexity of the expressions in the scalar evolutions analyzer.
+Complex expressions slow the analyzer.
+
@item omega-max-vars
The maximum number of variables in an Omega constraint system.
The default value is 128.
given basic block needs to have to be considered hot.
@item hot-bb-frequency-fraction
-Select fraction of the maximal frequency of executions of basic block in
-function given basic block needs to have to be considered hot
+Select fraction of the entry block frequency of executions of basic block in
+function given basic block needs to have to be considered hot.
@item max-predicted-iterations
The maximum number of loop iterations we predict statically. This is useful
The maximum number of best instructions in the ready list that are considered
for renaming in the selective scheduler. The default value is 2.
+@item sms-min-sc
+The minimum value of stage count that swing modulo scheduler will
+generate. The default value is 2.
+
@item max-last-value-rtl
The maximum size measured as number of RTLs that can be recorded in an expression
in combiner for a pseudo register as last known value of that register. The default
tracking analysis is completely disabled for the function. Setting
the parameter to zero makes it unlimited.
+@item max-vartrack-expr-depth
+Sets a maximum number of recursion levels when attempting to map
+variable names or debug temporaries to value expressions. This trades
+compile time for more complete debug information. If this is set too
+low, value expressions that are available and could be represented in
+debug information may end up not being used; setting this higher may
+enable the compiler to find more complex debug expressions, but compile
+time and memory use may grow. The default is 12.
+
@item min-nondebug-insn-uid
Use uids starting at this parameter for nondebug insns. The range below
the parameter is reserved exclusively for debug insns created by
length can be changed using the @option{loop-block-tile-size}
parameter. The default value is 51 iterations.
+@item ipa-cp-value-list-size
+IPA-CP attempts to track all possible values and types passed to a function's
+parameter in order to propagate them and perform devirtualization.
+@option{ipa-cp-value-list-size} is the maximum number of values and types it
+stores per one formal parameter of a function.
+
+@item lto-partitions
+Specify desired number of partitions produced during WHOPR compilation.
+The number of partitions should exceed the number of CPUs used for compilation.
+The default value is 32.
+
+@item lto-minpartition
+Size of minimal partition for WHOPR (in estimated instructions).
+This prevents expenses of splitting very small programs into too many
+partitions.
+
+@item cxx-max-namespaces-for-diagnostic-help
+The maximum number of namespaces to consult for suggestions when C++
+name lookup fails for an identifier. The default is 1000.
+
+@item max-stores-to-sink
+The maximum number of conditional stores paires that can be sunk. Set to 0
+if either vectorization (@option{-ftree-vectorize}) or if-conversion
+(@option{-ftree-loop-if-convert}) is disabled. The default is 2.
+
+@item allow-store-data-races
+Allow optimizers to introduce new data races on stores.
+Set to 1 to allow, otherwise to 0. This option is enabled by default
+unless implicitly set by the @option{-fmemory-model=} option.
+
+@item case-values-threshold
+The smallest number of different values for which it is best to use a
+jump-table instead of a tree of conditional branches. If the value is
+0, use the default for the machine. The default is 0.
+
+@item tree-reassoc-width
+Set the maximum number of instructions executed in parallel in
+reassociated tree. This parameter overrides target dependent
+heuristics used by default if has non zero value.
+
@end table
@end table
@table @code
@item %include <@var{file}>
-@cindex %include
+@cindex @code{%include}
Search for @var{file} and insert its text at the current point in the
specs file.
@item %include_noerr <@var{file}>
-@cindex %include_noerr
+@cindex @code{%include_noerr}
Just like @samp{%include}, but do not generate an error message if the include
file cannot be found.
@item %rename @var{old_name} @var{new_name}
-@cindex %rename
+@cindex @code{%rename}
Rename the spec string @var{old_name} to @var{new_name}.
@end table
string. All lines after this directive up to the next directive or
blank line are considered to be the text for the spec string. If this
results in an empty string then the spec will be deleted. (Or, if the
-spec did not exist, then nothing will happened.) Otherwise, if the spec
+spec did not exist, then nothing will happen.) Otherwise, if the spec
does not currently exist a new spec will be created. If the spec does
exist then its contents will be overridden by the text of this
directive, unless the first character of that text is the @samp{+}
@item %(@var{name})
Substitute the contents of spec string @var{name} at this point.
-@item %[@var{name}]
-Like @samp{%(@dots{})} but put @samp{__} around @option{-D} arguments.
-
@item %x@{@var{option}@}
Accumulate an option for @samp{%X}.
%@{fgnu-runtime:%:replace-outfile(-lobjc -lobjc-gnu)@}
@end smallexample
+@item @code{remove-outfile}
+The @code{remove-outfile} spec function takes one argument. It looks for the
+first argument in the outfiles array and removes it. Here is a small example
+its usage:
+
+@smallexample
+%:remove-outfile(-lm)
+@end smallexample
+
+@item @code{pass-through-libs}
+The @code{pass-through-libs} spec function takes any number of arguments. It
+finds any @option{-l} options and any non-options ending in ".a" (which it
+assumes are the names of linker input library archive files) and returns a
+result containing all the found arguments each prepended by
+@option{-plugin-opt=-pass-through=} and joined by spaces. This list is
+intended to be passed to the LTO linker plugin.
+
+@smallexample
+%:pass-through-libs(%G %L %G)
+@end smallexample
+
@item @code{print-asm-header}
The @code{print-asm-header} function takes no arguments and simply
prints a banner like:
@cindex compiler version, specifying
@cindex target machine, specifying
-The usual way to run GCC is to run the executable called @file{gcc}, or
-@file{<machine>-gcc} when cross-compiling, or
-@file{<machine>-gcc-<version>} to run a version other than the one that
-was installed last.
+The usual way to run GCC is to run the executable called @command{gcc}, or
+@command{@var{machine}-gcc} when cross-compiling, or
+@command{@var{machine}-gcc-@var{version}} to run a version other than the
+one that was installed last.
@node Submodel Options
@section Hardware Models and Configurations
@c in Machine Dependent Options
@menu
-* ARC Options::
* ARM Options::
* AVR Options::
* Blackfin Options::
+* C6X Options::
* CRIS Options::
-* CRX Options::
* Darwin Options::
* DEC Alpha Options::
* DEC Alpha/VMS Options::
* M32C Options::
* M32R/D Options::
* M680x0 Options::
-* M68hc1x Options::
* MCore Options::
* MeP Options::
+* MicroBlaze Options::
* MIPS Options::
* MMIX Options::
* MN10300 Options::
* S/390 and zSeries Options::
* Score Options::
* SH Options::
+* Solaris 2 Options::
* SPARC Options::
* SPU Options::
* System V Options::
* zSeries Options::
@end menu
-@node ARC Options
-@subsection ARC Options
-@cindex ARC Options
-
-These options are defined for ARC implementations:
-
-@table @gcctabopt
-@item -EL
-@opindex EL
-Compile code for little endian mode. This is the default.
-
-@item -EB
-@opindex EB
-Compile code for big endian mode.
-
-@item -mmangle-cpu
-@opindex mmangle-cpu
-Prepend the name of the cpu to all public symbol names.
-In multiple-processor systems, there are many ARC variants with different
-instruction and register set characteristics. This flag prevents code
-compiled for one cpu to be linked with code compiled for another.
-No facility exists for handling variants that are ``almost identical''.
-This is an all or nothing option.
-
-@item -mcpu=@var{cpu}
-@opindex mcpu
-Compile code for ARC variant @var{cpu}.
-Which variants are supported depend on the configuration.
-All variants support @option{-mcpu=base}, this is the default.
-
-@item -mtext=@var{text-section}
-@itemx -mdata=@var{data-section}
-@itemx -mrodata=@var{readonly-data-section}
-@opindex mtext
-@opindex mdata
-@opindex mrodata
-Put functions, data, and readonly data in @var{text-section},
-@var{data-section}, and @var{readonly-data-section} respectively
-by default. This can be overridden with the @code{section} attribute.
-@xref{Variable Attributes}.
-
-@end table
-
@node ARM Options
@subsection ARM Options
@cindex ARM options
@item -mthumb-interwork
@opindex mthumb-interwork
Generate code which supports calling between the ARM and Thumb
-instruction sets. Without this option the two instruction sets cannot
-be reliably used inside one program. The default is
-@option{-mno-thumb-interwork}, since slightly larger code is generated
-when @option{-mthumb-interwork} is specified.
+instruction sets. Without this option, on pre-v5 architectures, the
+two instruction sets cannot be reliably used inside one program. The
+default is @option{-mno-thumb-interwork}, since slightly larger code
+is generated when @option{-mthumb-interwork} is specified. In AAPCS
+configurations this option is meaningless.
@item -mno-sched-prolog
@opindex mno-sched-prolog
compile your entire program with the same ABI, and link with a
compatible set of libraries.
-@item -mhard-float
-@opindex mhard-float
-Equivalent to @option{-mfloat-abi=hard}.
-
-@item -msoft-float
-@opindex msoft-float
-Equivalent to @option{-mfloat-abi=soft}.
-
@item -mlittle-endian
@opindex mlittle-endian
Generate code for a processor running in little-endian mode. This is
order. That is, a byte order of the form @samp{32107654}. Note: this
option should only be used if you require compatibility with code for
big-endian ARM processors generated by versions of the compiler prior to
-2.8.
+2.8. This option is now deprecated.
@item -mcpu=@var{name}
@opindex mcpu
@samp{arm10e}, @samp{arm1020e}, @samp{arm1022e},
@samp{arm1136j-s}, @samp{arm1136jf-s}, @samp{mpcore}, @samp{mpcorenovfp},
@samp{arm1156t2-s}, @samp{arm1156t2f-s}, @samp{arm1176jz-s}, @samp{arm1176jzf-s},
-@samp{cortex-a5}, @samp{cortex-a8}, @samp{cortex-a9},
-@samp{cortex-r4}, @samp{cortex-r4f}, @samp{cortex-m4}, @samp{cortex-m3},
+@samp{cortex-a5}, @samp{cortex-a8}, @samp{cortex-a9}, @samp{cortex-a15},
+@samp{cortex-r4}, @samp{cortex-r4f}, @samp{cortex-r5},
+@samp{cortex-m4}, @samp{cortex-m3},
@samp{cortex-m1},
@samp{cortex-m0},
-@samp{xscale}, @samp{iwmmxt}, @samp{iwmmxt2}, @samp{ep9312}.
+@samp{xscale}, @samp{iwmmxt}, @samp{iwmmxt2}, @samp{ep9312},
+@samp{fa526}, @samp{fa626},
+@samp{fa606te}, @samp{fa626te}, @samp{fmp626}, @samp{fa726te}.
+
+
+@option{-mcpu=generic-@var{arch}} is also permissible, and is
+equivalent to @option{-march=@var{arch} -mtune=generic-@var{arch}}.
+See @option{-mtune} for more information.
+
+@option{-mcpu=native} causes the compiler to auto-detect the CPU
+of the build computer. At present, this feature is only supported on
+Linux, and not all architectures are recognised. If the auto-detect is
+unsuccessful the option has no effect.
@item -mtune=@var{name}
@opindex mtune
restricting which instructions can be used, it specifies that GCC should
tune the performance of the code as if the target were of the type
specified in this option, but still choosing the instructions that it
-will generate based on the cpu specified by a @option{-mcpu=} option.
+will generate based on the CPU specified by a @option{-mcpu=} option.
For some ARM implementations better performance can be obtained by using
this option.
+@option{-mtune=generic-@var{arch}} specifies that GCC should tune the
+performance for a blend of processors within architecture @var{arch}.
+The aim is to generate code that run well on the current most popular
+processors, balancing between optimizations that benefit some CPUs in the
+range, and avoiding performance pitfalls of other CPUs. The effects of
+this option may change in future GCC versions as CPU models come and go.
+
+@option{-mtune=native} causes the compiler to auto-detect the CPU
+of the build computer. At present, this feature is only supported on
+Linux, and not all architectures are recognised. If the auto-detect is
+unsuccessful the option has no effect.
+
@item -march=@var{name}
@opindex march
This specifies the name of the target ARM architecture. GCC uses this
@samp{armv7}, @samp{armv7-a}, @samp{armv7-r}, @samp{armv7-m},
@samp{iwmmxt}, @samp{iwmmxt2}, @samp{ep9312}.
+@option{-march=native} causes the compiler to auto-detect the architecture
+of the build computer. At present, this feature is only supported on
+Linux, and not all architectures are recognised. If the auto-detect is
+unsuccessful the option has no effect.
+
@item -mfpu=@var{name}
@itemx -mfpe=@var{number}
@itemx -mfp=@var{number}
If @option{-msoft-float} is specified this specifies the format of
floating point values.
+If the selected floating-point hardware includes the NEON extension
+(e.g. @option{-mfpu}=@samp{neon}), note that floating-point
+operations will not be used by GCC's auto-vectorization pass unless
+@option{-funsafe-math-optimizations} is also specified. This is
+because NEON hardware does not fully implement the IEEE 754 standard for
+floating-point arithmetic (in particular denormal values are treated as
+zero), so the use of NEON instructions may lead to a loss of precision.
+
@item -mfp16-format=@var{name}
@opindex mfp16-format
Specify the format of the @code{__fp16} half-precision floating-point type.
and has length @code{((pc[-3]) & 0xff000000)}.
@item -mthumb
+@itemx -marm
+@opindex marm
@opindex mthumb
-Generate code for the Thumb instruction set. The default is to
-use the 32-bit ARM instruction set.
-This option automatically enables either 16-bit Thumb-1 or
-mixed 16/32-bit Thumb-2 instructions based on the @option{-mcpu=@var{name}}
-and @option{-march=@var{name}} options. This option is not passed to the
-assembler. If you want to force assembler files to be interpreted as Thumb code,
-either add a @samp{.thumb} directive to the source or pass the @option{-mthumb}
-option directly to the assembler by prefixing it with @option{-Wa}.
+
+Select between generating code that executes in ARM and Thumb
+states. The default for most configurations is to generate code
+that executes in ARM state, but the default can be changed by
+configuring GCC with the @option{--with-mode=}@var{state}
+configure option.
@item -mtpcs-frame
@opindex mtpcs-frame
best available method for the selected processor. The default setting is
@option{auto}.
+@item -mtls-dialect=@var{dialect}
+@opindex mtls-dialect
+Specify the dialect to use for accessing thread local storage. Two
+dialects are supported --- @option{gnu} and @option{gnu2}. The
+@option{gnu} dialect selects the original GNU scheme for supporting
+local and global dynamic TLS models. The @option{gnu2} dialect
+selects the GNU descriptor scheme, which provides better performance
+for shared libraries. The GNU descriptor scheme is compatible with
+the original scheme, but does require new assembler, linker and
+library support. Initial and local exec TLS models are unaffected by
+this option and always use the original scheme.
+
@item -mword-relocations
@opindex mword-relocations
Only generate absolute relocations on word sized values (i.e. R_ARM_ABS32).
and long long will be 4 bytes. Please note that this option does not
comply to the C standards, but it will provide you with smaller code
size.
+
+@item -mstrict-X
+@opindex mstrict-X
+Use register @code{X} in a way proposed by the hardware. This means
+that @code{X} will only be used in indirect, post-increment or
+pre-decrement addressing.
+
+Without this option, the @code{X} register may be used in the same way
+as @code{Y} or @code{Z} which then is emulated by additional
+instructions.
+For example, loading a value with @code{X+const} addressing with a
+small @code{const <= 63} to a register @var{Rn} will be printed as
+@example
+adiw r26, const
+ld @var{Rn}, X
+sbiw r26, const
+@end example
@end table
@node Blackfin Options
@samp{bf534}, @samp{bf536}, @samp{bf537}, @samp{bf538}, @samp{bf539},
@samp{bf542}, @samp{bf544}, @samp{bf547}, @samp{bf548}, @samp{bf549},
@samp{bf542m}, @samp{bf544m}, @samp{bf547m}, @samp{bf548m}, @samp{bf549m},
-@samp{bf561}.
+@samp{bf561}, @samp{bf592}.
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.
are enabled; for standalone applications the default is off.
@end table
-@node CRIS Options
-@subsection CRIS Options
-@cindex CRIS Options
-
-These options are defined specifically for the CRIS ports.
+@node C6X Options
+@subsection C6X Options
+@cindex C6X Options
@table @gcctabopt
-@item -march=@var{architecture-type}
-@itemx -mcpu=@var{architecture-type}
+@item -march=@var{name}
@opindex march
-@opindex mcpu
-Generate code for the specified architecture. The choices for
-@var{architecture-type} are @samp{v3}, @samp{v8} and @samp{v10} for
-respectively ETRAX@w{ }4, ETRAX@w{ }100, and ETRAX@w{ }100@w{ }LX@.
-Default is @samp{v0} except for cris-axis-linux-gnu, where the default is
-@samp{v10}.
+This specifies the name of the target architecture. GCC uses this
+name to determine what kind of instructions it can emit when generating
+assembly code. Permissible names are: @samp{c62x},
+@samp{c64x}, @samp{c64x+}, @samp{c67x}, @samp{c67x+}, @samp{c674x}.
-@item -mtune=@var{architecture-type}
-@opindex mtune
+@item -mbig-endian
+@opindex mbig-endian
+Generate code for a big endian target.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate code for a little endian target. This is the default.
+
+@item -msim
+@opindex msim
+Choose startup files and linker script suitable for the simulator.
+
+@item -msdata=default
+@opindex msdata=default
+Put small global and static data in the @samp{.neardata} section,
+which is pointed to by register @code{B14}. Put small uninitialized
+global and static data in the @samp{.bss} section, which is adjacent
+to the @samp{.neardata} section. Put small read-only data into the
+@samp{.rodata} section. The corresponding sections used for large
+pieces of data are @samp{.fardata}, @samp{.far} and @samp{.const}.
+
+@item -msdata=all
+@opindex msdata=all
+Put all data, not just small objets, into the sections reserved for
+small data, and use addressing relative to the @code{B14} register to
+access them.
+
+@item -msdata=none
+@opindex msdata=none
+Make no use of the sections reserved for small data, and use absolute
+addresses to access all data. Put all initialized global and static
+data in the @samp{.fardata} section, and all uninitialized data in the
+@samp{.far} section. Put all constant data into the @samp{.const}
+section.
+@end table
+
+@node CRIS Options
+@subsection CRIS Options
+@cindex CRIS Options
+
+These options are defined specifically for the CRIS ports.
+
+@table @gcctabopt
+@item -march=@var{architecture-type}
+@itemx -mcpu=@var{architecture-type}
+@opindex march
+@opindex mcpu
+Generate code for the specified architecture. The choices for
+@var{architecture-type} are @samp{v3}, @samp{v8} and @samp{v10} for
+respectively ETRAX@w{ }4, ETRAX@w{ }100, and ETRAX@w{ }100@w{ }LX@.
+Default is @samp{v0} except for cris-axis-linux-gnu, where the default is
+@samp{v10}.
+
+@item -mtune=@var{architecture-type}
+@opindex mtune
Tune to @var{architecture-type} everything applicable about the generated
code, except for the ABI and the set of available instructions. The
choices for @var{architecture-type} are the same as for
0x40000000 and zero-initialized data at 0x80000000.
@end table
-@node CRX Options
-@subsection CRX Options
-@cindex CRX Options
-
-These options are defined specifically for the CRX ports.
-
-@table @gcctabopt
-
-@item -mmac
-@opindex mmac
-Enable the use of multiply-accumulate instructions. Disabled by default.
-
-@item -mpush-args
-@opindex mpush-args
-Push instructions will be used to pass outgoing arguments when functions
-are called. Enabled by default.
-@end table
-
@node Darwin Options
@subsection Darwin Options
@cindex Darwin options
@itemx -dynamic
@itemx -exported_symbols_list
@itemx -filelist
+@need 800
@itemx -flat_namespace
@itemx -force_flat_namespace
@itemx -headerpad_max_install_names
@itemx -multi_module
@itemx -multiply_defined
@itemx -multiply_defined_unused
+@need 800
@itemx -noall_load
@itemx -no_dead_strip_inits_and_terms
@itemx -nofixprebinding
@itemx -prebind
@itemx -prebind_all_twolevel_modules
@itemx -private_bundle
+@need 800
@itemx -read_only_relocs
@itemx -sectalign
@itemx -sectobjectsymbols
@itemx -sectorder
@itemx -segaddr
@itemx -segs_read_only_addr
+@need 800
@itemx -segs_read_write_addr
@itemx -seg_addr_table
@itemx -seg_addr_table_filename
@itemx -single_module
@itemx -static
@itemx -sub_library
+@need 800
@itemx -sub_umbrella
@itemx -twolevel_namespace
@itemx -umbrella
Schedules as an EV6 and supports the BWX, CIX, FIX, and MAX extensions.
@end table
-Native Linux/GNU toolchains also support the value @samp{native},
+Native toolchains also support the value @samp{native},
which selects the best architecture option for the host processor.
@option{-mcpu=native} has no effect if GCC does not recognize
the processor.
Set only the instruction scheduling parameters for machine type
@var{cpu_type}. The instruction set is not changed.
-Native Linux/GNU toolchains also support the value @samp{native},
+Native toolchains also support the value @samp{native},
which selects the best architecture option for the host processor.
@option{-mtune=native} has no effect if GCC does not recognize
the processor.
@var{cpu-type} are:
@table @emph
@item generic
-Produce code optimized for the most common IA32/AMD64/EM64T processors.
+Produce code optimized for the most common IA32/@/AMD64/@/EM64T processors.
If you know the CPU on which your code will run, then you should use
the corresponding @option{-mtune} option instead of
@option{-mtune=generic}. But, if you do not know exactly what CPU users
@item core2
Intel Core2 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3
instruction set support.
+@item corei7
+Intel Core i7 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1
+and SSE4.2 instruction set support.
+@item corei7-avx
+Intel Core i7 CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, AVX, AES and PCLMUL instruction set support.
+@item core-avx-i
+Intel Core CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, AVX, AES, PCLMUL, FSGSBASE, RDRND and F16C instruction
+set support.
@item atom
Intel Atom CPU with 64-bit extensions, MMX, SSE, SSE2, SSE3 and SSSE3
instruction set support.
@code{sqrt} instructions for the 387. Specify this option to avoid
generating those instructions. This option is the default on FreeBSD,
OpenBSD and NetBSD@. This option is overridden when @option{-march}
-indicates that the target cpu will always have an FPU and so the
+indicates that the target CPU will always have an FPU and so the
instruction will not need emulation. As of revision 2.6.1, these
instructions are not generated unless you also use the
@option{-funsafe-math-optimizations} switch.
modules with the same value, including any libraries. This includes
the system libraries and startup modules.
+@item -mvect8-ret-in-mem
+@opindex mvect8-ret-in-mem
+Return 8-byte vectors in memory instead of MMX registers. This is the
+default on Solaris@tie{}8 and 9 and VxWorks to match the ABI of the Sun
+Studio compilers until version 12. Later compiler versions (starting
+with Studio 12 Update@tie{}1) follow the ABI used by other x86 targets, which
+is the default on Solaris@tie{}10 and later. @emph{Only} use this option if
+you need to remain compatible with existing code produced by those
+previous compiler versions or older versions of GCC.
+
@item -mpc32
@itemx -mpc64
@itemx -mpc80
@itemx -mssse3
@itemx -mno-ssse3
@itemx -msse4.1
+@need 800
@itemx -mno-sse4.1
@itemx -msse4.2
@itemx -mno-sse4.2
@itemx -mno-sse4
@itemx -mavx
@itemx -mno-avx
+@itemx -mavx2
+@itemx -mno-avx2
@itemx -maes
@itemx -mno-aes
@itemx -mpclmul
+@need 800
@itemx -mno-pclmul
+@itemx -mfsgsbase
+@itemx -mno-fsgsbase
+@itemx -mrdrnd
+@itemx -mno-rdrnd
+@itemx -mf16c
+@itemx -mno-f16c
+@itemx -mfma
+@itemx -mno-fma
@itemx -msse4a
@itemx -mno-sse4a
@itemx -mfma4
+@need 800
@itemx -mno-fma4
@itemx -mxop
@itemx -mno-xop
@itemx -mno-popcnt
@itemx -mabm
@itemx -mno-abm
+@itemx -mbmi
+@itemx -mbmi2
+@itemx -mno-bmi
+@itemx -mno-bmi2
+@itemx -mlzcnt
+@itemx -mno-lzcnt
+@itemx -mtbm
+@itemx -mno-tbm
@opindex mmmx
@opindex mno-mmx
@opindex msse
@opindex mno-sse
@opindex m3dnow
@opindex mno-3dnow
-These switches enable or disable the use of instructions in the MMX,
-SSE, SSE2, SSE3, SSSE3, SSE4.1, AVX, AES, PCLMUL, SSE4A, FMA4, XOP,
-LWP, ABM or 3DNow!@: extended instruction sets.
+These switches enable or disable the use of instructions in the MMX, SSE,
+SSE2, SSE3, SSSE3, SSE4.1, AVX, AVX2, AES, PCLMUL, FSGSBASE, RDRND, F16C,
+FMA, SSE4A, FMA4, XOP, LWP, ABM, BMI, BMI2, LZCNT 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
disabled by these switches.
the file containing the CPU detection code should be compiled without
these options.
-@item -mfused-madd
-@itemx -mno-fused-madd
-@opindex mfused-madd
-@opindex mno-fused-madd
-Do (don't) generate code that uses the fused multiply/add or multiply/subtract
-instructions. The default is to use these instructions.
-
@item -mcld
@opindex mcld
This option instructs GCC to emit a @code{cld} instruction in the prologue
instructions can be suppressed with the @option{-mno-cld} compiler option
in this case.
+@item -mvzeroupper
+@opindex mvzeroupper
+This option instructs GCC to emit a @code{vzeroupper} instruction
+before a transfer of control flow out of the function to minimize
+AVX to SSE transition penalty as well as remove unnecessary zeroupper
+intrinsics.
+
@item -mcx16
@opindex mcx16
This option will enable GCC to use CMPXCHG16B instruction in generated code.
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).
-Note that GCC implements 1.0f/sqrtf(x) in terms of RSQRTSS (or RSQRTPS)
+Note that GCC implements @code{1.0f/sqrtf(@var{x})} in terms of RSQRTSS
+(or RSQRTPS) already with @option{-ffast-math} (or the above option
+combination), and doesn't need @option{-mrecip}.
+
+Also note that GCC emits the above sequence with additional Newton-Raphson step
+for vectorized single float division and vectorized @code{sqrtf(@var{x})}
already with @option{-ffast-math} (or the above option combination), and
doesn't need @option{-mrecip}.
+@item -mrecip=@var{opt}
+@opindex mrecip=opt
+This option allows to control which reciprocal estimate instructions
+may be used. @var{opt} is a comma separated list of options, that may
+be preceded by a @code{!} to invert the option:
+@code{all}: enable all estimate instructions,
+@code{default}: enable the default instructions, equivalent to @option{-mrecip},
+@code{none}: disable all estimate instructions, equivalent to @option{-mno-recip},
+@code{div}: enable the approximation for scalar division,
+@code{vec-div}: enable the approximation for vectorized division,
+@code{sqrt}: enable the approximation for scalar square root,
+@code{vec-sqrt}: enable the approximation for vectorized square root.
+
+So for example, @option{-mrecip=all,!sqrt} would enable
+all of the reciprocal approximations, except for square root.
+
@item -mveclibabi=@var{type}
@opindex mveclibabi
Specifies the ABI type to use for vectorizing intrinsics using an
using the function attribute @samp{ms_abi}/@samp{sysv_abi}.
@xref{Function Attributes}.
+@item -mtls-dialect=@var{type}
+@opindex mtls-dialect
+Generate code to access thread-local storage using the @samp{gnu} or
+@samp{gnu2} conventions. @samp{gnu} is the conservative default;
+@samp{gnu2} is more efficient, but it may add compile- and run-time
+requirements that cannot be satisfied on all systems.
+
@item -mpush-args
@itemx -mno-push-args
@opindex mpush-args
@opindex msse2avx
Specify that the assembler should encode SSE instructions with VEX
prefix. The option @option{-mavx} turns this on by default.
+
+@item -mfentry
+@itemx -mno-fentry
+@opindex mfentry
+If profiling is active @option{-pg} put the profiling
+counter call before prologue.
+Note: On x86 architectures the attribute @code{ms_hook_prologue}
+isn't possible at the moment for @option{-mfentry} and @option{-pg}.
+
+@item -m8bit-idiv
+@itemx -mno-8bit-idiv
+@opindex 8bit-idiv
+On some processors, like Intel Atom, 8bit unsigned integer divide is
+much faster than 32bit/64bit integer divide. This option will generate a
+runt-time check. If both dividend and divisor are within range of 0
+to 255, 8bit unsigned integer divide will be used instead of
+32bit/64bit integer divide.
+
+@item -mavx256-split-unaligned-load
+@item -mavx256-split-unaligned-store
+@opindex avx256-split-unaligned-load
+@opindex avx256-split-unaligned-store
+Split 32-byte AVX unaligned load and store.
+
@end table
These @samp{-m} switches are supported in addition to the above
@table @gcctabopt
@item -m32
@itemx -m64
+@itemx -mx32
@opindex m32
@opindex m64
+@opindex mx32
Generate code for a 32-bit or 64-bit environment.
-The 32-bit environment sets int, long and pointer to 32 bits and
+The @option{-m32} option sets int, long and pointer to 32 bits and
generates code that runs on any i386 system.
-The 64-bit environment sets int to 32 bits and long and pointer
-to 64 bits and generates code for AMD's x86-64 architecture. For
-darwin only the -m64 option turns off the @option{-fno-pic} and
-@option{-mdynamic-no-pic} options.
+The @option{-m64} option sets int to 32 bits and long and pointer
+to 64 bits and generates code for AMD's x86-64 architecture.
+The @option{-mx32} option sets int, long and pointer to 32 bits and
+generates code for AMD's x86-64 architecture.
+For darwin only the @option{-m64} option turns off the @option{-fno-pic}
+and @option{-mdynamic-no-pic} options.
@item -mno-red-zone
@opindex mno-red-zone
about addresses and sizes of sections.
@end table
+@node i386 and x86-64 Windows Options
+@subsection i386 and x86-64 Windows Options
+@cindex i386 and x86-64 Windows Options
+
+These additional options are available for Windows targets:
+
+@table @gcctabopt
+@item -mconsole
+@opindex mconsole
+This option is available for Cygwin and MinGW targets. It
+specifies that a console application is to be generated, by
+instructing the linker to set the PE header subsystem type
+required for console applications.
+This is the default behavior for Cygwin and MinGW targets.
+
+@item -mdll
+@opindex mdll
+This option is available for Cygwin and MinGW targets. It
+specifies that a DLL - a dynamic link library - is to be
+generated, enabling the selection of the required runtime
+startup object and entry point.
+
+@item -mnop-fun-dllimport
+@opindex mnop-fun-dllimport
+This option is available for Cygwin and MinGW targets. It
+specifies that the dllimport attribute should be ignored.
+
+@item -mthread
+@opindex mthread
+This option is available for MinGW targets. It specifies
+that MinGW-specific thread support is to be used.
+
+@item -municode
+@opindex municode
+This option is available for mingw-w64 targets. It specifies
+that the UNICODE macro is getting pre-defined and that the
+unicode capable runtime startup code is chosen.
+
+@item -mwin32
+@opindex mwin32
+This option is available for Cygwin and MinGW targets. It
+specifies that the typical Windows pre-defined macros are to
+be set in the pre-processor, but does not influence the choice
+of runtime library/startup code.
+
+@item -mwindows
+@opindex mwindows
+This option is available for Cygwin and MinGW targets. It
+specifies that a GUI application is to be generated by
+instructing the linker to set the PE header subsystem type
+appropriately.
+
+@item -fno-set-stack-executable
+@opindex fno-set-stack-executable
+This option is available for MinGW targets. It specifies that
+the executable flag for stack used by nested functions isn't
+set. This is necessary for binaries running in kernel mode of
+Windows, as there the user32 API, which is used to set executable
+privileges, isn't available.
+
+@item -mpe-aligned-commons
+@opindex mpe-aligned-commons
+This option is available for Cygwin and MinGW targets. It
+specifies that the GNU extension to the PE file format that
+permits the correct alignment of COMMON variables should be
+used when generating code. It will be enabled by default if
+GCC detects that the target assembler found during configuration
+supports the feature.
+@end table
+
+See also under @ref{i386 and x86-64 Options} for standard options.
+
@node IA-64 Options
@subsection IA-64 Options
@cindex IA-64 Options
@end table
-@node M68hc1x Options
-@subsection M68hc1x Options
-@cindex M68hc1x options
-
-These are the @samp{-m} options defined for the 68hc11 and 68hc12
-microcontrollers. The default values for these options depends on
-which style of microcontroller was selected when the compiler was configured;
-the defaults for the most common choices are given below.
-
-@table @gcctabopt
-@item -m6811
-@itemx -m68hc11
-@opindex m6811
-@opindex m68hc11
-Generate output for a 68HC11. This is the default
-when the compiler is configured for 68HC11-based systems.
-
-@item -m6812
-@itemx -m68hc12
-@opindex m6812
-@opindex m68hc12
-Generate output for a 68HC12. This is the default
-when the compiler is configured for 68HC12-based systems.
-
-@item -m68S12
-@itemx -m68hcs12
-@opindex m68S12
-@opindex m68hcs12
-Generate output for a 68HCS12.
-
-@item -mauto-incdec
-@opindex mauto-incdec
-Enable the use of 68HC12 pre and post auto-increment and auto-decrement
-addressing modes.
-
-@item -minmax
-@itemx -mnominmax
-@opindex minmax
-@opindex mnominmax
-Enable the use of 68HC12 min and max instructions.
-
-@item -mlong-calls
-@itemx -mno-long-calls
-@opindex mlong-calls
-@opindex mno-long-calls
-Treat all calls as being far away (near). If calls are assumed to be
-far away, the compiler will use the @code{call} instruction to
-call a function and the @code{rtc} instruction for returning.
-
-@item -mshort
-@opindex mshort
-Consider type @code{int} to be 16 bits wide, like @code{short int}.
-
-@item -msoft-reg-count=@var{count}
-@opindex msoft-reg-count
-Specify the number of pseudo-soft registers which are used for the
-code generation. The maximum number is 32. Using more pseudo-soft
-register may or may not result in better code depending on the program.
-The default is 4 for 68HC11 and 2 for 68HC12.
-
-@end table
-
@node MCore Options
@subsection MCore Options
@cindex MCore options
@end table
+@node MicroBlaze Options
+@subsection MicroBlaze Options
+@cindex MicroBlaze Options
+
+@table @gcctabopt
+
+@item -msoft-float
+@opindex msoft-float
+Use software emulation for floating point (default).
+
+@item -mhard-float
+@opindex mhard-float
+Use hardware floating point instructions.
+
+@item -mmemcpy
+@opindex mmemcpy
+Do not optimize block moves, use @code{memcpy}.
+
+@item -mno-clearbss
+@opindex mno-clearbss
+This option is deprecated. Use @option{-fno-zero-initialized-in-bss} instead.
+
+@item -mcpu=@var{cpu-type}
+@opindex mcpu=
+Use features of and schedule code for given CPU.
+Supported values are in the format @samp{v@var{X}.@var{YY}.@var{Z}},
+where @var{X} is a major version, @var{YY} is the minor version, and
+@var{Z} is compatibility code. Example values are @samp{v3.00.a},
+@samp{v4.00.b}, @samp{v5.00.a}, @samp{v5.00.b}, @samp{v5.00.b}, @samp{v6.00.a}.
+
+@item -mxl-soft-mul
+@opindex mxl-soft-mul
+Use software multiply emulation (default).
+
+@item -mxl-soft-div
+@opindex mxl-soft-div
+Use software emulation for divides (default).
+
+@item -mxl-barrel-shift
+@opindex mxl-barrel-shift
+Use the hardware barrel shifter.
+
+@item -mxl-pattern-compare
+@opindex mxl-pattern-compare
+Use pattern compare instructions.
+
+@item -msmall-divides
+@opindex msmall-divides
+Use table lookup optimization for small signed integer divisions.
+
+@item -mxl-stack-check
+@opindex mxl-stack-check
+This option is deprecated. Use -fstack-check instead.
+
+@item -mxl-gp-opt
+@opindex mxl-gp-opt
+Use GP relative sdata/sbss sections.
+
+@item -mxl-multiply-high
+@opindex mxl-multiply-high
+Use multiply high instructions for high part of 32x32 multiply.
+
+@item -mxl-float-convert
+@opindex mxl-float-convert
+Use hardware floating point conversion instructions.
+
+@item -mxl-float-sqrt
+@opindex mxl-float-sqrt
+Use hardware floating point square root instruction.
+
+@item -mxl-mode-@var{app-model}
+Select application model @var{app-model}. Valid models are
+@table @samp
+@item executable
+normal executable (default), uses startup code @file{crt0.o}.
+
+@item xmdstub
+for use with Xilinx Microprocessor Debugger (XMD) based
+software intrusive debug agent called xmdstub. This uses startup file
+@file{crt1.o} and sets the start address of the program to be 0x800.
+
+@item bootstrap
+for applications that are loaded using a bootloader.
+This model uses startup file @file{crt2.o} which does not contain a processor
+reset vector handler. This is suitable for transferring control on a
+processor reset to the bootloader rather than the application.
+
+@item novectors
+for applications that do not require any of the
+MicroBlaze vectors. This option may be useful for applications running
+within a monitoring application. This model uses @file{crt3.o} as a startup file.
+@end table
+
+Option @option{-xl-mode-@var{app-model}} is a deprecated alias for
+@option{-mxl-mode-@var{app-model}}.
+
+@end table
+
@node MIPS Options
@subsection MIPS Options
@cindex MIPS options
@samp{34kc}, @samp{34kf2_1}, @samp{34kf1_1},
@samp{74kc}, @samp{74kf2_1}, @samp{74kf1_1}, @samp{74kf3_2},
@samp{1004kc}, @samp{1004kf2_1}, @samp{1004kf1_1},
-@samp{loongson2e}, @samp{loongson2f},
+@samp{loongson2e}, @samp{loongson2f}, @samp{loongson3a},
@samp{m4k},
@samp{octeon},
@samp{orion},
most compatible architecture for the selected ABI (that is,
@samp{mips1} for 32-bit ABIs and @samp{mips3} for 64-bit ABIs)@.
-Native Linux/GNU toolchains also support the value @samp{native},
+Native Linux/GNU and IRIX toolchains also support the value @samp{native},
which selects the best architecture option for the host processor.
@option{-march=native} has no effect if GCC does not recognize
the processor.
can use @option{-mgp32} to get 32-bit code instead.
For information about the O64 ABI, see
-@w{@uref{http://gcc.gnu.org/projects/mipso64-abi.html}}.
+@uref{http://gcc.gnu.org/@/projects/@/mipso64-abi.html}.
GCC supports a variant of the o32 ABI in which floating-point registers
are 64 rather than 32 bits wide. You can select this combination with
Tell the MIPS assembler to not run its preprocessor over user
assembler files (with a @samp{.s} suffix) when assembling them.
+@item -mfix-24k
+@item -mno-fix-24k
+@opindex mfix-24k
+@opindex mno-fix-24k
+Work around the 24K E48 (lost data on stores during refill) errata.
+The workarounds are implemented by the assembler rather than by GCC.
+
@item -mfix-r4000
@itemx -mno-fix-r4000
@opindex mfix-r4000
Do not generate code which uses features specific to the AM33 processor. This
is the default.
+@item -mam33-2
+@opindex mam33-2
+Generate code which uses features specific to the AM33/2.0 processor.
+
+@item -mam34
+@opindex mam34
+Generate code which uses features specific to the AM34 processor.
+
+@item -mtune=@var{cpu-type}
+@opindex mtune
+Use the timing characteristics of the indicated CPU type when
+scheduling instructions. This does not change the targeted processor
+type. The CPU type must be one of @samp{mn10300}, @samp{am33},
+@samp{am33-2} or @samp{am34}.
+
@item -mreturn-pointer-on-d0
@opindex mreturn-pointer-on-d0
When generating a function which returns a pointer, return the pointer
has an effect when used on the command line for the final link step.
This option makes symbolic debugging impossible.
+
+@item -mliw
+@opindex mliw
+Allow the compiler to generate @emph{Long Instruction Word}
+instructions if the target is the @samp{AM33} or later. This is the
+default. This option defines the preprocessor macro @samp{__LIW__}.
+
+@item -mnoliw
+@opindex mnoliw
+Do not allow the compiler to generate @emph{Long Instruction Word}
+instructions. This option defines the preprocessor macro
+@samp{__NO_LIW__}.
+
+@item -msetlb
+@opindex msetlb
+Allow the compiler to generate the @emph{SETLB} and @emph{Lcc}
+instructions if the target is the @samp{AM33} or later. This is the
+default. This option defines the preprocessor macro @samp{__SETLB__}.
+
+@item -mnosetlb
+@opindex mnosetlb
+Do not allow the compiler to generate @emph{SETLB} or @emph{Lcc}
+instructions. This option defines the preprocessor macro
+@samp{__NO_SETLB__}.
+
@end table
@node PDP-11 Options
@opindex mbranch-cheap
Do not pretend that branches are expensive. This is the default.
-@item -msplit
-@opindex msplit
-Generate code for a system with split I&D@.
-
-@item -mno-split
-@opindex mno-split
-Generate code for a system without split I&D@. This is the default.
-
@item -munix-asm
@opindex munix-asm
Use Unix assembler syntax. This is the default when configured for
@itemx -mno-powerpc-gpopt
@itemx -mpowerpc-gfxopt
@itemx -mno-powerpc-gfxopt
+@need 800
@itemx -mpowerpc64
@itemx -mno-powerpc64
@itemx -mmfcrf
@itemx -mno-popcntd
@itemx -mfprnd
@itemx -mno-fprnd
+@need 800
@itemx -mcmpb
@itemx -mno-cmpb
@itemx -mmfpgpr
@samp{7400}, @samp{7450}, @samp{750}, @samp{801}, @samp{821}, @samp{823},
@samp{860}, @samp{970}, @samp{8540}, @samp{a2}, @samp{e300c2},
@samp{e300c3}, @samp{e500mc}, @samp{e500mc64}, @samp{ec603e}, @samp{G3},
-@samp{G4}, @samp{G5}, @samp{power}, @samp{power2}, @samp{power3},
+@samp{G4}, @samp{G5}, @samp{titan}, @samp{power}, @samp{power2}, @samp{power3},
@samp{power4}, @samp{power5}, @samp{power5+}, @samp{power6}, @samp{power6x},
@samp{power7}, @samp{common}, @samp{powerpc}, @samp{powerpc64}, @samp{rios},
@samp{rios1}, @samp{rios2}, @samp{rsc}, and @samp{rs64}.
@opindex mfused-madd
@opindex mno-fused-madd
Generate code that uses (does not use) the floating point multiply and
-accumulate instructions. These instructions are generated by default if
-hardware floating is used.
+accumulate instructions. These instructions are generated by default
+if hardware floating point is used. The machine dependent
+@option{-mfused-madd} option is now mapped to the machine independent
+@option{-ffp-contract=fast} option, and @option{-mno-fused-madd} is
+mapped to @option{-ffp-contract=off}.
@item -mmulhw
@itemx -mno-mulhw
@itemx -mno-relocatable
@opindex mrelocatable
@opindex mno-relocatable
-On embedded PowerPC systems generate code that allows (does not allow)
-the program to be relocated to a different address at runtime. If you
-use @option{-mrelocatable} on any module, all objects linked together must
-be compiled with @option{-mrelocatable} or @option{-mrelocatable-lib}.
+Generate code that allows (does not allow) a static executable to be
+relocated to a different address at runtime. A simple embedded
+PowerPC system loader should relocate the entire contents of
+@code{.got2} and 4-byte locations listed in the @code{.fixup} section,
+a table of 32-bit addresses generated by this option. For this to
+work, all objects linked together must be compiled with
+@option{-mrelocatable} or @option{-mrelocatable-lib}.
+@option{-mrelocatable} code aligns the stack to an 8 byte boundary.
@item -mrelocatable-lib
@itemx -mno-relocatable-lib
@opindex mrelocatable-lib
@opindex mno-relocatable-lib
-On embedded PowerPC systems generate code that allows (does not allow)
-the program to be relocated to a different address at runtime. Modules
-compiled with @option{-mrelocatable-lib} can be linked with either modules
-compiled without @option{-mrelocatable} and @option{-mrelocatable-lib} or
-with modules compiled with the @option{-mrelocatable} options.
+Like @option{-mrelocatable}, @option{-mrelocatable-lib} generates a
+@code{.fixup} section to allow static executables to be relocated at
+runtime, but @option{-mrelocatable-lib} does not use the smaller stack
+alignment of @option{-mrelocatable}. Objects compiled with
+@option{-mrelocatable-lib} may be linked with objects compiled with
+any combination of the @option{-mrelocatable} options.
@item -mno-toc
@itemx -mtoc
resulting code is suitable for applications, but not shared
libraries.
+@item -msingle-pic-base
+@opindex msingle-pic-base
+Treat the register used for PIC addressing as read-only, rather than
+loading it in the prologue for each function. The run-time system is
+responsible for initializing this register with an appropriate value
+before execution begins.
+
@item -mprioritize-restricted-insns=@var{priority}
@opindex mprioritize-restricted-insns
This option controls the priority that is assigned to
On System V.4 and embedded PowerPC systems compile code for the
Linux-based GNU system.
-@item -mcall-gnu
-@opindex mcall-gnu
-On System V.4 and embedded PowerPC systems compile code for the
-Hurd-based GNU system.
-
@item -mcall-freebsd
@opindex mcall-freebsd
On System V.4 and embedded PowerPC systems compile code for the
in the @samp{.data} section, and all uninitialized data in the
@samp{.bss} section.
+@item -mblock-move-inline-limit=@var{num}
+@opindex mblock-move-inline-limit
+Inline all block moves (such as calls to @code{memcpy} or structure
+copies) less than or equal to @var{num} bytes. The minimum value for
+@var{num} is 32 bytes on 32-bit targets and 64 bytes on 64-bit
+targets. The default value is target-specific.
+
@item -G @var{num}
@opindex G
@cindex smaller data references (PowerPC)
@opindex mrecip=opt
This option allows to control which reciprocal estimate instructions
may be used. @var{opt} is a comma separated list of options, that may
-be preceeded by a @code{!} to invert the option:
+be preceded by a @code{!} to invert the option:
@code{all}: enable all estimate instructions,
-@code{default}: enable the default instructions, equvalent to @option{-mrecip},
+@code{default}: enable the default instructions, equivalent to @option{-mrecip},
@code{none}: disable all estimate instructions, equivalent to @option{-mno-recip};
@code{div}: enable the reciprocal approximation instructions for both single and double precision;
@code{divf}: enable the single precision reciprocal approximation instructions;
precision square root estimate instructions are not generated by
default on low precision machines, since they do not provide an
estimate that converges after three steps.
+
+@item -mveclibabi=@var{type}
+@opindex mveclibabi
+Specifies the ABI type to use for vectorizing intrinsics using an
+external library. The only type supported at present is @code{mass},
+which specifies to use IBM's Mathematical Acceleration Subsystem
+(MASS) libraries for vectorizing intrinsics using external libraries.
+GCC will currently emit calls to @code{acosd2}, @code{acosf4},
+@code{acoshd2}, @code{acoshf4}, @code{asind2}, @code{asinf4},
+@code{asinhd2}, @code{asinhf4}, @code{atan2d2}, @code{atan2f4},
+@code{atand2}, @code{atanf4}, @code{atanhd2}, @code{atanhf4},
+@code{cbrtd2}, @code{cbrtf4}, @code{cosd2}, @code{cosf4},
+@code{coshd2}, @code{coshf4}, @code{erfcd2}, @code{erfcf4},
+@code{erfd2}, @code{erff4}, @code{exp2d2}, @code{exp2f4},
+@code{expd2}, @code{expf4}, @code{expm1d2}, @code{expm1f4},
+@code{hypotd2}, @code{hypotf4}, @code{lgammad2}, @code{lgammaf4},
+@code{log10d2}, @code{log10f4}, @code{log1pd2}, @code{log1pf4},
+@code{log2d2}, @code{log2f4}, @code{logd2}, @code{logf4},
+@code{powd2}, @code{powf4}, @code{sind2}, @code{sinf4}, @code{sinhd2},
+@code{sinhf4}, @code{sqrtd2}, @code{sqrtf4}, @code{tand2},
+@code{tanf4}, @code{tanhd2}, and @code{tanhf4} when generating code
+for power7. Both @option{-ftree-vectorize} and
+@option{-funsafe-math-optimizations} have to be enabled. The MASS
+libraries will have to be specified at link time.
+
+@item -mfriz
+@itemx -mno-friz
+@opindex mfriz
+Generate (do not generate) the @code{friz} instruction when the
+@option{-funsafe-math-optimizations} option is used to optimize
+rounding a floating point value to 64-bit integer and back to floating
+point. The @code{friz} instruction does not return the same value if
+the floating point number is too large to fit in an integer.
+
+@item -mpointers-to-nested-functions
+@itemx -mno-pointers-to-nested-functions
+@opindex mpointers-to-nested-functions
+Generate (do not generate) code to load up the static chain register
+(@var{r11}) when calling through a pointer on AIX and 64-bit Linux
+systems where a function pointer points to a 3 word descriptor giving
+the function address, TOC value to be loaded in register @var{r2}, and
+static chain value to be loaded in register @var{r11}. The
+@option{-mpointers-to-nested-functions} is on by default. You will
+not be able to call through pointers to nested functions or pointers
+to functions compiled in other languages that use the static chain if
+you use the @option{-mno-pointers-to-nested-functions}.
+
+@item -msave-toc-indirect
+@itemx -mno-save-toc-indirect
+@opindex msave-toc-indirect
+Generate (do not generate) code to save the TOC value in the reserved
+stack location in the function prologue if the function calls through
+a pointer on AIX and 64-bit Linux systems. If the TOC value is not
+saved in the prologue, it is saved just before the call through the
+pointer. The @option{-mno-save-toc-indirect} option is the default.
@end table
@node RX Options
This is because the RX FPU instructions are themselves unsafe.
@item -mcpu=@var{name}
-@itemx -patch=@var{name}
@opindex -mcpu
-@opindex -patch
Selects the type of RX CPU to be targeted. Currently three types are
supported, the generic @var{RX600} and @var{RX200} series hardware and
-the specific @var{RX610} cpu. The default is @var{RX600}.
+the specific @var{RX610} CPU. The default is @var{RX600}.
The only difference between @var{RX600} and @var{RX610} is that the
@var{RX610} does not support the @code{MVTIPL} instruction.
@opindex mbig-endian-data
@opindex mlittle-endian-data
Store data (but not code) in the big-endian format. The default is
-@option{-mlittle-endian-data}, ie to store data in the little endian
+@option{-mlittle-endian-data}, i.e.@: to store data in the little endian
format.
@item -msmall-data-limit=@var{N}
area can lead to smaller and faster code, but the size of area is
limited and it is up to the programmer to ensure that the area does
not overflow. Also when the small data area is used one of the RX's
-registers (@code{r13}) is reserved for use pointing to this area, so
-it is no longer available for use by the compiler. This could result
-in slower and/or larger code if variables which once could have been
-held in @code{r13} are now pushed onto the stack.
+registers (usually @code{r13}) is reserved for use pointing to this
+area, so it is no longer available for use by the compiler. This
+could result in slower and/or larger code if variables which once
+could have been held in the reserved register are now pushed onto the
+stack.
Note, common variables (variables which have not been initialised) and
constants are not placed into the small data area as they are assigned
The default value is zero, which disables this feature. Note, this
feature is not enabled by default with higher optimization levels
(@option{-O2} etc) because of the potentially detrimental effects of
-reserving register @code{r13}. It is up to the programmer to
-experiment and discover whether this feature is of benefit to their
-program.
+reserving a register. It is up to the programmer to experiment and
+discover whether this feature is of benefit to their program. See the
+description of the @option{-mpid} option for a description of how the
+actual register to hold the small data area pointer is chosen.
@item -msim
@itemx -mno-sim
multiplications. The default is to ignore the accumulator as this
makes the interrupt handlers faster.
+@item -mpid
+@itemx -mno-pid
+@opindex mpid
+@opindex mno-pid
+Enables the generation of position independent data. When enabled any
+access to constant data will done via an offset from a base address
+held in a register. This allows the location of constant data to be
+determined at run-time without requiring the executable to be
+relocated, which is a benefit to embedded applications with tight
+memory constraints. Data that can be modified is not affected by this
+option.
+
+Note, using this feature reserves a register, usually @code{r13}, for
+the constant data base address. This can result in slower and/or
+larger code, especially in complicated functions.
+
+The actual register chosen to hold the constant data base address
+depends upon whether the @option{-msmall-data-limit} and/or the
+@option{-mint-register} command line options are enabled. Starting
+with register @code{r13} and proceeding downwards, registers are
+allocated first to satisfy the requirements of @option{-mint-register},
+then @option{-mpid} and finally @option{-msmall-data-limit}. Thus it
+is possible for the small data area register to be @code{r8} if both
+@option{-mint-register=4} and @option{-mpid} are specified on the
+command line.
+
+By default this feature is not enabled. The default can be restored
+via the @option{-mno-pid} command line option.
+
@end table
@emph{Note:} The generic GCC command line @option{-ffixed-@var{reg}}
@opindex mhitachi
Comply with the calling conventions defined for GCC before the Renesas
conventions were available. This option is the default for all
-targets of the SH toolchain except for @samp{sh-symbianelf}.
+targets of the SH toolchain.
@item -mnomacsave
@opindex mnomacsave
@item -maccumulate-outgoing-args
@opindex maccumulate-outgoing-args
-Reserve space once for outgoing arguments in the function prologue rather
+Reserve space once for outgoing arguments in the function prologue rather
than around each call. Generally beneficial for performance and size. Also
needed for unwinding to avoid changing the stack frame around conditional code.
of symbol loads. The default is @option{-mno-invalid-symbols}.
@end table
+@node Solaris 2 Options
+@subsection Solaris 2 Options
+@cindex Solaris 2 options
+
+These @samp{-m} options are supported on Solaris 2:
+
+@table @gcctabopt
+@item -mimpure-text
+@opindex mimpure-text
+@option{-mimpure-text}, used in addition to @option{-shared}, tells
+the compiler to not pass @option{-z text} to the linker when linking a
+shared object. Using this option, you can link position-dependent
+code into a shared object.
+
+@option{-mimpure-text} suppresses the ``relocations remain against
+allocatable but non-writable sections'' linker error message.
+However, the necessary relocations will trigger copy-on-write, and the
+shared object is not actually shared across processes. Instead of
+using @option{-mimpure-text}, you should compile all source code with
+@option{-fpic} or @option{-fPIC}.
+
+@end table
+
+These switches are supported in addition to the above on Solaris 2:
+
+@table @gcctabopt
+@item -pthreads
+@opindex pthreads
+Add support for multithreading using the POSIX threads library. This
+option sets flags for both the preprocessor and linker. This option does
+not affect the thread safety of object code produced by the compiler or
+that of libraries supplied with it.
+
+@item -pthread
+@opindex pthread
+This is a synonym for @option{-pthreads}.
+@end table
+
@node SPARC Options
@subsection SPARC Options
@cindex SPARC options
specify @option{-mno-app-regs}. You should compile libraries and system
software with this option.
+@item -mflat
+@itemx -mno-flat
+@opindex mflat
+@opindex mno-flat
+With @option{-mflat}, the compiler does not generate save/restore instructions
+and uses a ``flat'' or single register window model. This model is compatible
+with the regular register window model. The local registers and the input
+registers (0--5) are still treated as ``call-saved'' registers and will be
+saved on the stack as needed.
+
+With @option{-mno-flat} (the default), the compiler generates save/restore
+instructions (except for leaf functions). This is the normal operating mode.
+
@item -mfpu
@itemx -mhard-float
@opindex mfpu
acknowledges that their resulting code will not be directly in line with
the rules of the ABI@.
-@item -mimpure-text
-@opindex mimpure-text
-@option{-mimpure-text}, used in addition to @option{-shared}, tells
-the compiler to not pass @option{-z text} to the linker when linking a
-shared object. Using this option, you can link position-dependent
-code into a shared object.
-
-@option{-mimpure-text} suppresses the ``relocations remain against
-allocatable but non-writable sections'' linker error message.
-However, the necessary relocations will trigger copy-on-write, and the
-shared object is not actually shared across processes. Instead of
-using @option{-mimpure-text}, you should compile all source code with
-@option{-fpic} or @option{-fPIC}.
-
-This option is only available on SunOS and Solaris.
-
@item -mcpu=@var{cpu_type}
@opindex mcpu
Set the instruction set, register set, and instruction scheduling parameters
for machine type @var{cpu_type}. Supported values for @var{cpu_type} are
-@samp{v7}, @samp{cypress}, @samp{v8}, @samp{supersparc}, @samp{sparclite},
-@samp{f930}, @samp{f934}, @samp{hypersparc}, @samp{sparclite86x},
+@samp{v7}, @samp{cypress}, @samp{v8}, @samp{supersparc}, @samp{hypersparc},
+@samp{leon}, @samp{sparclite}, @samp{f930}, @samp{f934}, @samp{sparclite86x},
@samp{sparclet}, @samp{tsc701}, @samp{v9}, @samp{ultrasparc},
-@samp{ultrasparc3}, @samp{niagara} and @samp{niagara2}.
+@samp{ultrasparc3}, @samp{niagara}, @samp{niagara2}, @samp{niagara3},
+and @samp{niagara4}.
+
+Native Solaris and GNU/Linux toolchains also support the value @samp{native},
+which selects the best architecture option for the host processor.
+@option{-mcpu=native} has no effect if GCC does not recognize
+the processor.
Default instruction scheduling parameters are used for values that select
an architecture and not an implementation. These are @samp{v7}, @samp{v8},
@smallexample
v7: cypress
- v8: supersparc, hypersparc
+ v8: supersparc, hypersparc, leon
sparclite: f930, f934, sparclite86x
sparclet: tsc701
- v9: ultrasparc, ultrasparc3, niagara, niagara2
+ v9: ultrasparc, ultrasparc3, niagara, niagara2, niagara3, niagara4
@end smallexample
By default (unless configured otherwise), GCC generates code for the V7
Sun UltraSPARC III/III+/IIIi/IIIi+/IV/IV+ chips. With
@option{-mcpu=niagara}, the compiler additionally optimizes it for
Sun UltraSPARC T1 chips. With @option{-mcpu=niagara2}, the compiler
-additionally optimizes it for Sun UltraSPARC T2 chips.
+additionally optimizes it for Sun UltraSPARC T2 chips. With
+@option{-mcpu=niagara3}, the compiler additionally optimizes it for Sun
+UltraSPARC T3 chips. With @option{-mcpu=niagara4}, the compiler
+additionally optimizes it for Sun UltraSPARC T4 chips.
@item -mtune=@var{cpu_type}
@opindex mtune
The same values for @option{-mcpu=@var{cpu_type}} can be used for
@option{-mtune=@var{cpu_type}}, but the only useful values are those
-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}, @samp{niagara}, and @samp{niagara2}.
+that select a particular CPU implementation. Those are @samp{cypress},
+@samp{supersparc}, @samp{hypersparc}, @samp{leon}, @samp{f930}, @samp{f934},
+@samp{sparclite86x}, @samp{tsc701}, @samp{ultrasparc}, @samp{ultrasparc3},
+@samp{niagara}, @samp{niagara2}, @samp{niagara3} and @samp{niagara4}. With
+native Solaris and GNU/Linux toolchains, @samp{native} can also be used.
@item -mv8plus
@itemx -mno-v8plus
@opindex mno-vis
With @option{-mvis}, GCC generates code that takes advantage of the UltraSPARC
Visual Instruction Set extensions. The default is @option{-mno-vis}.
+
+@item -mvis2
+@itemx -mno-vis2
+@opindex mvis2
+@opindex mno-vis2
+With @option{-mvis2}, GCC generates code that takes advantage of
+version 2.0 of the UltraSPARC Visual Instruction Set extensions. The
+default is @option{-mvis2} when targetting a cpu that supports such
+instructions, such as UltraSPARC-III and later. Setting @option{-mvis2}
+also sets @option{-mvis}.
+
+@item -mvis3
+@itemx -mno-vis3
+@opindex mvis3
+@opindex mno-vis3
+With @option{-mvis3}, GCC generates code that takes advantage of
+version 3.0 of the UltraSPARC Visual Instruction Set extensions. The
+default is @option{-mvis3} when targetting a cpu that supports such
+instructions, such as niagara-3 and later. Setting @option{-mvis3}
+also sets @option{-mvis2} and @option{-mvis}.
+
+@item -mpopc
+@itemx -mno-popc
+@opindex mpopc
+@opindex mno-popc
+With @option{-mpopc}, GCC generates code that takes advantage of the UltraSPARC
+population count instruction. The default is @option{-mpopc}
+when targetting a cpu that supports such instructions, such as Niagara-2 and
+later.
+
+@item -mfmaf
+@itemx -mno-fmaf
+@opindex mfmaf
+@opindex mno-fmaf
+With @option{-mfmaf}, GCC generates code that takes advantage of the UltraSPARC
+Fused Multiply-Add Floating-point extensions. The default is @option{-mfmaf}
+when targetting a cpu that supports such instructions, such as Niagara-3 and
+later.
+
+@item -mfix-at697f
+@opindex mfix-at697f
+Enable the documented workaround for the single erratum of the Atmel AT697F
+processor (which corresponds to erratum #13 of the AT697E processor).
@end table
These @samp{-m} options are supported in addition to the above
Otherwise, assume no such offset is present.
@end table
-These switches are supported in addition to the above on Solaris:
-
-@table @gcctabopt
-@item -threads
-@opindex threads
-Add support for multithreading using the Solaris threads library. This
-option sets flags for both the preprocessor and linker. This option does
-not affect the thread safety of object code produced by the compiler or
-that of libraries supplied with it.
-
-@item -pthreads
-@opindex pthreads
-Add support for multithreading using the POSIX threads library. This
-option sets flags for both the preprocessor and linker. This option does
-not affect the thread safety of object code produced by the compiler or
-that of libraries supplied with it.
-
-@item -pthread
-@opindex pthread
-This is a synonym for @option{-pthreads}.
-@end table
-
@node SPU Options
@subsection SPU Options
@cindex SPU options
@opindex mno-app-regs
This option will cause r2 and r5 to be treated as fixed registers.
+@item -mv850e2v3
+@opindex mv850e2v3
+Specify that the target processor is the V850E2V3. The preprocessor
+constants @samp{__v850e2v3__} will be defined if
+this option is used.
+
+@item -mv850e2
+@opindex mv850e2
+Specify that the target processor is the V850E2. The preprocessor
+constants @samp{__v850e2__} will be defined if this option is used.
+
@item -mv850e1
@opindex mv850e1
Specify that the target processor is the V850E1. The preprocessor
constants @samp{__v850e1__} and @samp{__v850e__} will be defined if
this option is used.
+@item -mv850es
+@opindex mv850es
+Specify that the target processor is the V850ES. This is an alias for
+the @option{-mv850e1} option.
+
@item -mv850e
@opindex mv850e
Specify that the target processor is the V850E@. The preprocessor
constant @samp{__v850e__} will be defined if this option is used.
If neither @option{-mv850} nor @option{-mv850e} nor @option{-mv850e1}
+nor @option{-mv850e2} nor @option{-mv850e2v3}
are defined then a default target processor will be chosen and the
relevant @samp{__v850*__} preprocessor constant will be defined.
@item -mdisable-callt
@opindex mdisable-callt
This option will suppress generation of the CALLT instruction for the
-v850e and v850e1 flavors of the v850 architecture. The default is
+v850e, v850e1, v850e2 and v850e2v3 flavors of the v850 architecture. The default is
@option{-mno-disable-callt} which allows the CALLT instruction to be used.
@end table
These are listed under @xref{i386 and x86-64 Options}.
-@node i386 and x86-64 Windows Options
-@subsection i386 and x86-64 Windows Options
-@cindex i386 and x86-64 Windows Options
-
-These additional options are available for Windows targets:
-
-@table @gcctabopt
-@item -mconsole
-@opindex mconsole
-This option is available for Cygwin and MinGW targets. It
-specifies that a console application is to be generated, by
-instructing the linker to set the PE header subsystem type
-required for console applications.
-This is the default behavior for Cygwin and MinGW targets.
-
-@item -mcygwin
-@opindex mcygwin
-This option is available for Cygwin targets. It specifies that
-the Cygwin internal interface is to be used for predefined
-preprocessor macros, C runtime libraries and related linker
-paths and options. For Cygwin targets this is the default behavior.
-This option is deprecated and will be removed in a future release.
-
-@item -mno-cygwin
-@opindex mno-cygwin
-This option is available for Cygwin targets. It specifies that
-the MinGW internal interface is to be used instead of Cygwin's, by
-setting MinGW-related predefined macros and linker paths and default
-library options.
-This option is deprecated and will be removed in a future release.
-
-@item -mdll
-@opindex mdll
-This option is available for Cygwin and MinGW targets. It
-specifies that a DLL - a dynamic link library - is to be
-generated, enabling the selection of the required runtime
-startup object and entry point.
-
-@item -mnop-fun-dllimport
-@opindex mnop-fun-dllimport
-This option is available for Cygwin and MinGW targets. It
-specifies that the dllimport attribute should be ignored.
-
-@item -mthread
-@opindex mthread
-This option is available for MinGW targets. It specifies
-that MinGW-specific thread support is to be used.
-
-@item -municode
-@opindex municode
-This option is available for mingw-w64 targets. It specifies
-that the UNICODE macro is getting pre-defined and that the
-unicode capable runtime startup code is chosen.
-
-@item -mwin32
-@opindex mwin32
-This option is available for Cygwin and MinGW targets. It
-specifies that the typical Windows pre-defined macros are to
-be set in the pre-processor, but does not influence the choice
-of runtime library/startup code.
-
-@item -mwindows
-@opindex mwindows
-This option is available for Cygwin and MinGW targets. It
-specifies that a GUI application is to be generated by
-instructing the linker to set the PE header subsystem type
-appropriately.
-
-@item -fno-set-stack-executable
-@opindex fno-set-stack-executable
-This option is available for MinGW targets. It specifies that
-the executable flag for stack used by nested functions isn't
-set. This is necessary for binaries running in kernel mode of
-Windows, as there the user32 API, which is used to set executable
-privileges, isn't available.
-
-@item -mpe-aligned-commons
-@opindex mpe-aligned-commons
-This option is available for Cygwin and MinGW targets. It
-specifies that the GNU extension to the PE file format that
-permits the correct alignment of COMMON variables should be
-used when generating code. It will be enabled by default if
-GCC detects that the target assembler found during configuration
-supports the feature.
-@end table
-
-See also under @ref{i386 and x86-64 Options} for standard options.
-
@node Xstormy16 Options
@subsection Xstormy16 Options
@cindex Xstormy16 Options
switch is related to the @option{-fverbose-asm} switch, but that
switch only records information in the assembler output file as
comments, so it never reaches the object file.
+See also @option{-grecord-gcc-switches} for another
+way of storing compiler options into the object file.
@item -fpic
@opindex fpic
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}
+For example:
+
+@smallexample
+-finstrument-functions-exclude-file-list=/bits/stl,include/sys
+@end smallexample
+
+@noindent
will exclude any inline function defined in files whose pathnames
contain @code{/bits/stl} or @code{include/sys}.
@option{-Wl,--defsym,__stack_limit=0x7ffe0000} to enforce a stack limit
of 128KB@. Note that this may only work with the GNU linker.
+@item -fsplit-stack
+@opindex fsplit-stack
+Generate code to automatically split the stack before it overflows.
+The resulting program has a discontiguous stack which can only
+overflow if the program is unable to allocate any more memory. This
+is most useful when running threaded programs, as it is no longer
+necessary to calculate a good stack size to use for each thread. This
+is currently only implemented for the i386 and x86_64 backends running
+GNU/Linux.
+
+When code compiled with @option{-fsplit-stack} calls code compiled
+without @option{-fsplit-stack}, there may not be much stack space
+available for the latter code to run. If compiling all code,
+including library code, with @option{-fsplit-stack} is not an option,
+then the linker can fix up these calls so that the code compiled
+without @option{-fsplit-stack} always has a large stack. Support for
+this is implemented in the gold linker in GNU binutils release 2.21
+and later.
+
@item -fleading-underscore
@opindex fleading-underscore
This option and its counterpart, @option{-fno-leading-underscore}, forcibly
It is @strong{strongly} recommended that you use this in any shared objects
you distribute.
-Despite the nomenclature, @code{default} always means public ie;
+Despite the nomenclature, @code{default} always means public; i.e.,
available to be linked against from outside the shared object.
@code{protected} and @code{internal} are pretty useless in real-world
usage so the only other commonly used option will be @code{hidden}.
@samp{#pragma GCC visibility pop}.
Bear in mind that symbol visibility should be viewed @strong{as
part of the API interface contract} and thus all new code should
-always specify visibility when it is not the default ie; declarations
+always specify visibility when it is not the default; i.e., declarations
only for use within the local DSO should @strong{always} be marked explicitly
as hidden as so to avoid PLT indirection overheads---making this
abundantly clear also aids readability and self-documentation of the code.
the DSOs.
An overview of these techniques, their benefits and how to use them
-is at @w{@uref{http://gcc.gnu.org/wiki/Visibility}}.
+is at @uref{http://gcc.gnu.org/@/wiki/@/Visibility}.
@item -fstrict-volatile-bitfields
+@opindex fstrict-volatile-bitfields
This option should be used if accesses to volatile bitfields (or other
structure fields, although the compiler usually honors those types
-anyway) should use a single access in a mode of the same size as the
-container's type, aligned to a natural alignment if possible. For
+anyway) should use a single access of the width of the
+field's type, aligned to a natural alignment if possible. For
example, targets with memory-mapped peripheral registers might require
all such accesses to be 16 bits wide; with this flag the user could
declare all peripheral bitfields as ``unsigned short'' (assuming short
any portion of the bitfield, or memory-mapped registers unrelated to
the one being updated.
-If the target requires strict alignment, and honoring the container
+If the target requires strict alignment, and honoring the field
type would require violating this alignment, a warning is issued.
-However, the access happens as the user requested, under the
-assumption that the user knows something about the target hardware
-that GCC is unaware of.
+If the field has @code{packed} attribute, the access is done without
+honoring the field type. If the field doesn't have @code{packed}
+attribute, the access is done honoring the field type. In both cases,
+GCC assumes that the user knows something about the target hardware
+that it is unaware of.
The default value of this option is determined by the application binary
interface for the target processor.
the output of the preprocessor, which is the input to the compiler
proper.
+@item GCC_COMPARE_DEBUG
+@findex GCC_COMPARE_DEBUG
+Setting @env{GCC_COMPARE_DEBUG} is nearly equivalent to passing
+@option{-fcompare-debug} to the compiler driver. See the documentation
+of this option for more details.
+
@item GCC_EXEC_PREFIX
@findex GCC_EXEC_PREFIX
If @env{GCC_EXEC_PREFIX} is set, it specifies a prefix to use in the
@gccoptlist{-fmessage-length= -fpreprocessed -fsched-interblock @gol
-fsched-spec -fsched-spec-load -fsched-spec-load-dangerous @gol
--fsched-verbose=<number> -fschedule-insns -fvisibility= @gol
+-fsched-verbose=@var{number} -fschedule-insns -fvisibility= @gol
-pedantic-errors}
@end itemize
OSDN Git Service
