@table @emph
@item Overall Options
@xref{Overall Options,,Options Controlling the Kind of Output}.
-@gccoptlist{-c -S -E -o @var{file} -combine -pipe -pass-exit-codes @gol
+@gccoptlist{-c -S -E -o @var{file} -combine -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}}
-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} -Wignored-qualifiers @gol
+-Wframe-larger-than=@var{len} -Wjump-misses-init -Wignored-qualifiers @gol
-Wimplicit -Wimplicit-function-declaration -Wimplicit-int @gol
-Winit-self -Winline @gol
-Wno-int-to-pointer-cast -Wno-invalid-offsetof @gol
-Wswitch -Wswitch-default -Wswitch-enum -Wsync-nand @gol
-Wsystem-headers -Wtrigraphs -Wtype-limits -Wundef -Wuninitialized @gol
-Wunknown-pragmas -Wno-pragmas -Wunreachable-code @gol
--Wunused -Wunused-function -Wunused-label -Wunused-parameter @gol
--Wunused-value -Wunused-variable @gol
+-Wunsuffixed-float-constants -Wunused -Wunused-function @gol
+-Wunused-label -Wunused-parameter -Wno-unused-result -Wunused-value -Wunused-variable @gol
-Wvariadic-macros -Wvla @gol
-Wvolatile-register-var -Wwrite-strings}
@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
--fdump-noaddr -fdump-unnumbered @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-tree-gimple@r{[}-raw@r{]} -fdump-tree-mudflap@r{[}-@var{n}@r{]} @gol
-fdump-tree-dom@r{[}-@var{n}@r{]} @gol
-fdump-tree-dse@r{[}-@var{n}@r{]} @gol
+-fdump-tree-phiprop@r{[}-@var{n}@r{]} @gol
-fdump-tree-phiopt@r{[}-@var{n}@r{]} @gol
-fdump-tree-forwprop@r{[}-@var{n}@r{]} @gol
-fdump-tree-copyrename@r{[}-@var{n}@r{]} @gol
-fdump-tree-nrv -fdump-tree-vect @gol
-fdump-tree-sink @gol
-fdump-tree-sra@r{[}-@var{n}@r{]} @gol
+-fdump-tree-forwprop@r{[}-@var{n}@r{]} @gol
-fdump-tree-fre@r{[}-@var{n}@r{]} @gol
-fdump-tree-vrp@r{[}-@var{n}@r{]} @gol
-ftree-vectorizer-verbose=@var{n} @gol
-fdump-tree-storeccp@r{[}-@var{n}@r{]} @gol
+-fdump-final-insns=@var{file} @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
-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
--g -g@var{level} -gcoff -gdwarf-2 @gol
--ggdb -gstabs -gstabs+ -gvms -gxcoff -gxcoff+ @gol
+-fvar-tracking-assigments -fvar-tracking-assignments-toggle @gol
+-g -g@var{level} -gtoggle -gcoff -gdwarf-@var{version} @gol
+-ggdb -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
-femit-struct-debug-baseonly -femit-struct-debug-reduced @gol
-femit-struct-debug-detailed@r{[}=@var{spec-list}@r{]} @gol
-p -pg -print-file-name=@var{library} -print-libgcc-file-name @gol
--print-multi-directory -print-multi-lib @gol
+-print-multi-directory -print-multi-lib -print-multi-os-directory @gol
-print-prog-name=@var{program} -print-search-dirs -Q @gol
-print-sysroot -print-sysroot-headers-suffix @gol
--save-temps -save-temps=cwd -save-temps=obj -time}
+-save-temps -save-temps=cwd -save-temps=obj -time@r{[}=@var{file}@r{]}}
@item Optimization Options
@xref{Optimize Options,,Options that Control Optimization}.
-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 -fexpensive-optimizations -ffast-math @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
-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
+-finline-small-functions -fipa-cp -fipa-cp-clone -fipa-matrix-reorg -fipa-pta @gol
-fipa-pure-const -fipa-reference -fipa-struct-reorg @gol
-fipa-type-escape -fira-algorithm=@var{algorithm} @gol
--fira-region=@var{region} -fira-coalesce -fno-ira-share-save-slots @gol
+-fira-region=@var{region} -fira-coalesce @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 @gol
--fmerge-all-constants -fmerge-constants -fmodulo-sched @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
-fno-defer-pop -fno-function-cse -fno-guess-branch-probability @gol
-freorder-blocks-and-partition -freorder-functions @gol
-frerun-cse-after-loop -freschedule-modulo-scheduled-loops @gol
-frounding-math -fsched2-use-superblocks @gol
--fsched2-use-traces -fsched-spec-load -fsched-spec-load-dangerous @gol
+-fsched2-use-traces -fsched-pressure @gol
+-fsched-spec-load -fsched-spec-load-dangerous @gol
-fsched-stalled-insns-dep[=@var{n}] -fsched-stalled-insns[=@var{n}] @gol
--fschedule-insns -fschedule-insns2 -fsection-anchors -fsee @gol
+-fsched-group-heuristic -fsched-critical-path-heuristic @gol
+-fsched-spec-insn-heuristic -fsched-rank-heuristic @gol
+-fsched-last-insn-heuristic -fsched-dep-count-heuristic @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
-fstrict-aliasing -fstrict-overflow -fthread-jumps -ftracer @gol
-ftree-builtin-call-dce -ftree-ccp -ftree-ch -ftree-copy-prop @gol
-ftree-copyrename -ftree-dce @gol
--ftree-dominator-opts -ftree-dse -ftree-fre -ftree-loop-im @gol
--ftree-loop-distribution @gol
+-ftree-dominator-opts -ftree-dse -ftree-forwprop -ftree-fre -ftree-loop-im @gol
+-ftree-phiprop -ftree-loop-distribution @gol
-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
--ftree-parallelize-loops=@var{n} -ftree-pre -ftree-reassoc @gol
+-ftree-parallelize-loops=@var{n} -ftree-pre -ftree-pta -ftree-reassoc @gol
-ftree-sink -ftree-sra -ftree-switch-conversion @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 @gol
+-fwhole-program -fwhopr -fwpa -use-linker-plugin @gol
--param @var{name}=@var{value}
-O -O0 -O1 -O2 -O3 -Os}
@xref{Link Options,,Options for Linking}.
@gccoptlist{@var{object-file-name} -l@var{library} @gol
-nostartfiles -nodefaultlibs -nostdlib -pie -rdynamic @gol
--s -static -static-libgcc -shared -shared-libgcc -symbolic @gol
+-s -static -static-libgcc -static-libstdc++ -shared @gol
+-shared-libgcc -symbolic @gol
-T @var{script} -Wl,@var{option} -Xlinker @var{option} @gol
-u @var{symbol}}
-msched-prolog -mno-sched-prolog @gol
-mlittle-endian -mbig-endian -mwords-little-endian @gol
-mfloat-abi=@var{name} -msoft-float -mhard-float -mfpe @gol
+-mfp16-format=@var{name}
-mthumb-interwork -mno-thumb-interwork @gol
-mcpu=@var{name} -march=@var{name} -mfpu=@var{name} @gol
-mstructure-size-boundary=@var{n} @gol
-mfix-cortex-m3-ldrd}
@emph{AVR Options}
-@gccoptlist{-mmcu=@var{mcu} -msize -minit-stack=@var{n} -mno-interrupts @gol
+@gccoptlist{-mmcu=@var{mcu} -mno-interrupts @gol
-mcall-prologues -mtiny-stack -mint8}
@emph{Blackfin Options}
-mmemory-latency=@var{time}}
@emph{DEC Alpha/VMS Options}
-@gccoptlist{-mvms-return-codes}
+@gccoptlist{-mvms-return-codes -mdebug-main=@var{prefix} -mmalloc64}
@emph{FR30 Options}
@gccoptlist{-msmall-model -mno-lsim}
-mno-wide-multiply -mrtd -malign-double @gol
-mpreferred-stack-boundary=@var{num}
-mincoming-stack-boundary=@var{num}
--mcld -mcx16 -msahf -mrecip @gol
+-mcld -mcx16 -msahf -mmovbe -mcrc32 -mrecip @gol
-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 -mavx @gol
-maes -mpclmul @gol
--msse4a -m3dnow -mpopcnt -mabm -msse5 @gol
+-msse4a -m3dnow -mpopcnt -mabm -mfma4 @gol
-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
-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
--mfused-madd -mno-fused-madd -msse2avx}
+-msse2avx}
@emph{IA-64 Options}
@gccoptlist{-mbig-endian -mlittle-endian -mgnu-as -mgnu-ld -mno-pic @gol
--mvolatile-asm-stop -mregister-names -mno-sdata @gol
--mconstant-gp -mauto-pic -minline-float-divide-min-latency @gol
+-mvolatile-asm-stop -mregister-names -msdata -mno-sdata @gol
+-mconstant-gp -mauto-pic -mfused-madd @gol
+-minline-float-divide-min-latency @gol
-minline-float-divide-max-throughput @gol
+-mno-inline-float-divide @gol
-minline-int-divide-min-latency @gol
-minline-int-divide-max-throughput @gol
+-mno-inline-int-divide @gol
-minline-sqrt-min-latency -minline-sqrt-max-throughput @gol
--mno-dwarf2-asm -mearly-stop-bits @gol
+-mno-inline-sqrt @gol
+-mdwarf2-asm -mearly-stop-bits @gol
-mfixed-range=@var{register-range} -mtls-size=@var{tls-size} @gol
--mtune=@var{cpu-type} -mt -pthread -milp32 -mlp64 @gol
--mno-sched-br-data-spec -msched-ar-data-spec -mno-sched-control-spec @gol
+-mtune=@var{cpu-type} -milp32 -mlp64 @gol
+-msched-br-data-spec -msched-ar-data-spec -msched-control-spec @gol
-msched-br-in-data-spec -msched-ar-in-data-spec -msched-in-control-spec @gol
--msched-ldc -mno-sched-control-ldc -mno-sched-spec-verbose @gol
--mno-sched-prefer-non-data-spec-insns @gol
--mno-sched-prefer-non-control-spec-insns @gol
--mno-sched-count-spec-in-critical-path}
+-msched-spec-ldc -msched-spec-control-ldc @gol
+-msched-prefer-non-data-spec-insns -msched-prefer-non-control-spec-insns @gol
+-msched-stop-bits-after-every-cycle -msched-count-spec-in-critical-path @gol
+-msel-sched-dont-check-control-spec -msched-fp-mem-deps-zero-cost @gol
+-msched-max-memory-insns-hard-limit -msched-max-memory-insns=@var{max-insns}}
+
+@emph{IA-64/VMS Options}
+@gccoptlist{-mvms-return-codes -mdebug-main=@var{prefix} -mmalloc64}
@emph{M32R/D Options}
@gccoptlist{-m32r2 -m32rx -m32r @gol
-mno-callgraph-data -mslow-bytes -mno-slow-bytes -mno-lsim @gol
-mlittle-endian -mbig-endian -m210 -m340 -mstack-increment}
+@emph{MeP Options}
+@gccoptlist{-mabsdiff -mall-opts -maverage -mbased=@var{n} -mbitops @gol
+-mc=@var{n} -mclip -mconfig=@var{name} -mcop -mcop32 -mcop64 -mivc2 @gol
+-mdc -mdiv -meb -mel -mio-volatile -ml -mleadz -mm -mminmax @gol
+-mmult -mno-opts -mrepeat -ms -msatur -msdram -msim -msimnovec -mtf @gol
+-mtiny=@var{n}}
+
@emph{MIPS Options}
@gccoptlist{-EL -EB -march=@var{arch} -mtune=@var{arch} @gol
-mips1 -mips2 -mips3 -mips4 -mips32 -mips32r2 @gol
-mflush-func=@var{func} -mno-flush-func @gol
-mbranch-cost=@var{num} -mbranch-likely -mno-branch-likely @gol
-mfp-exceptions -mno-fp-exceptions @gol
--mvr4130-align -mno-vr4130-align}
+-mvr4130-align -mno-vr4130-align -msynci -mno-synci @gol
+-mrelax-pic-calls -mno-relax-pic-calls}
@emph{MMIX Options}
@gccoptlist{-mlibfuncs -mno-libfuncs -mepsilon -mno-epsilon -mabi=gnu @gol
-maltivec -mno-altivec @gol
-mpowerpc-gpopt -mno-powerpc-gpopt @gol
-mpowerpc-gfxopt -mno-powerpc-gfxopt @gol
--mmfcrf -mno-mfcrf -mpopcntb -mno-popcntb -mfprnd -mno-fprnd @gol
+-mmfcrf -mno-mfcrf -mpopcntb -mno-popcntb -mpopcntd -mno-popcntd @gol
+-mfprnd -mno-fprnd @gol
-mcmpb -mno-cmpb -mmfpgpr -mno-mfpgpr -mhard-dfp -mno-hard-dfp @gol
-mnew-mnemonics -mold-mnemonics @gol
-mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc @gol
-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 @gol
-mprioritize-restricted-insns=@var{priority} @gol
-msched-costly-dep=@var{dependence_type} @gol
-minsert-sched-nops=@var{scheme} @gol
-msim -mmvme -mads -myellowknife -memb -msdata @gol
-msdata=@var{opt} -mvxworks -G @var{num} -pthread}
+@emph{RX Options}
+@gccoptlist{-m64bit-doubles -m32bit-doubles -mieee -mno-ieee@gol
+-mbig-endian-data -mlittle-endian-data @gol
+-msmall-data @gol
+-msim -mno-sim@gol
+-mas100-syntax -mno-as100-syntax@gol
+-mrelax@gol
+-mmax-constant-size=@gol
+-mint-register=}
+
@emph{S/390 and zSeries Options}
@gccoptlist{-mtune=@var{cpu-type} -march=@var{cpu-type} @gol
-mhard-float -msoft-float -mhard-dfp -mno-hard-dfp @gol
-mscore5 -mscore5u -mscore7 -mscore7d}
@emph{SH Options}
-@gccoptlist{-m1 -m2 -m2e -m3 -m3e @gol
+@gccoptlist{-m1 -m2 -m2e @gol
+-m2a-nofpu -m2a-single-only -m2a-single -m2a @gol
+-m3 -m3e @gol
-m4-nofpu -m4-single-only -m4-single -m4 @gol
-m4a-nofpu -m4a-single-only -m4a-single -m4a -m4al @gol
-m5-64media -m5-64media-nofpu @gol
-m5-32media -m5-32media-nofpu @gol
-m5-compact -m5-compact-nofpu @gol
-mb -ml -mdalign -mrelax @gol
--mbigtable -mfmovd -mhitachi -mrenesas -mno-renesas -mnomacsave @gol
+-mbigtable -mfmovd -mhitachi -mrenesas -mno-renesas -mnomacsave @gol
-mieee -mbitops -misize -minline-ic_invalidate -mpadstruct -mspace @gol
-mprefergot -musermode -multcost=@var{number} -mdiv=@var{strategy} @gol
-mdivsi3_libfunc=@var{name} -mfixed-range=@var{register-range} @gol
@emph{i386 and x86-64 Windows Options}
@gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll
--mnop-fun-dllimport -mthread -mwin32 -mwindows}
+-mnop-fun-dllimport -mthread -municode -mwin32 -mwindows}
@emph{Xstormy16 Options}
@gccoptlist{-msim}
option.
@item @var{language}
-This will display the options supported for @var{language}, where
-@var{language} is the name of one of the languages supported in this
+This will display the options supported for @var{language}, where
+@var{language} is the name of one of the languages supported in this
version of GCC.
@item @samp{common}
diff /tmp/O2-opts /tmp/O3-opts | grep enabled
@end smallexample
+@item -no-canonical-prefixes
+@opindex no-canonical-prefixes
+Do not expand any symbolic links, resolve references to @samp{/../}
+or @samp{/./}, or make the path absolute when generating a relative
+prefix.
+
@item --version
@opindex version
Display the version number and copyrights of the invoked GCC@.
@opindex std
Determine the language standard. @xref{Standards,,Language Standards
Supported by GCC}, for details of these standard versions. This option
-is currently only supported when compiling C or C++.
+is currently only supported when compiling C or C++.
The compiler can accept several base standards, such as @samp{c89} or
@samp{c++98}, and GNU dialects of those standards, such as
Enable handling of OpenMP directives @code{#pragma omp} in C/C++ and
@code{!$omp} in Fortran. When @option{-fopenmp} is specified, the
compiler generates parallel code according to the OpenMP Application
-Program Interface v2.5 @w{@uref{http://www.openmp.org/}}. This option
+Program Interface v3.0 @w{@uref{http://www.openmp.org/}}. This option
implies @option{-pthread}, and thus is only supported on targets that
have support for @option{-pthread}.
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 -fno-deduce-init-list
+@opindex fno-deduce-init-list
+Disable deduction of a template type parameter as
+std::initializer_list from a brace-enclosed initializer list, i.e.
+
+@smallexample
+template <class T> auto forward(T t) -> decltype (realfn (t))
+@{
+ return realfn (t);
+@}
+
+void f()
+@{
+ forward(@{1,2@}); // call forward<std::initializer_list<int>>
+@}
+@end smallexample
+
+This option is present because this deduction is an extension to the
+current specification in the C++0x working draft, and there was
+some concern about potential overload resolution problems.
+
@item -ffriend-injection
@opindex ffriend-injection
Inject friend functions into the enclosing namespace, so that they are
Set the maximum instantiation depth for template classes to @var{n}.
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.
+conforming programs must not rely on a maximum depth greater than 17
+(changed to 1024 in C++0x).
@item -fno-threadsafe-statics
@opindex fno-threadsafe-statics
A pointer is compared against integer zero with @samp{<}, @samp{<=},
@samp{>}, or @samp{>=}.
-@item
+@item
(C++ only) An enumerator and a non-enumerator both appear in a
conditional expression.
-@item
+@item
(C++ only) Ambiguous virtual bases.
-@item
+@item
(C++ only) Subscripting an array which has been declared @samp{register}.
-@item
+@item
(C++ only) Taking the address of a variable which has been declared
@samp{register}.
-@item
+@item
(C++ only) A base class is not initialized in a derived class' copy
constructor.
to @code{int}. Also warn about any @code{return} statement with no
return-value in a function whose return-type is not @code{void}
(falling off the end of the function body is considered returning
-without a value), and about a @code{return} statement with a
+without a value), and about a @code{return} statement with an
expression in a function whose return-type is @code{void}.
For C++, a function without return type always produces a diagnostic
and lacks a @code{case} for one or more of the named codes of that
enumeration. (The presence of a @code{default} label prevents this
warning.) @code{case} labels outside the enumeration range also
-provoke warnings when this option is used.
+provoke warnings when this option is used (even if there is a
+@code{default} label).
This warning is enabled by @option{-Wall}.
@item -Wswitch-default
Warn whenever a @code{switch} statement has an index of enumerated type
and lacks a @code{case} for one or more of the named codes of that
enumeration. @code{case} labels outside the enumeration range also
-provoke warnings when this option is used.
+provoke warnings when this option is used. The only difference
+between @option{-Wswitch} and this option is that this option gives a
+warning about an omitted enumeration code even if there is a
+@code{default} label.
@item -Wsync-nand @r{(C and C++ only)}
@opindex Wsync-nand
To suppress this warning use the @samp{unused} attribute
(@pxref{Variable Attributes}).
+@item -Wno-unused-result
+@opindex Wunused-result
+@opindex Wno-unused-result
+Do not warn if a caller of a function marked with attribute
+@code{warn_unused_result} (@pxref{Variable Attributes}) does not use
+its return value. The default is @option{-Wunused-result}.
+
@item -Wunused-variable
@opindex Wunused-variable
@opindex Wno-unused-variable
Level 1: Most aggressive, quick, least accurate.
Possibly useful when higher levels
-do not warn but -fstrict-aliasing still breaks the code, as it has very few
+do not warn but -fstrict-aliasing still breaks the code, as it has very few
false negatives. However, it has many false positives.
-Warns for all pointer conversions between possibly incompatible types,
+Warns for all pointer conversions between possibly incompatible types,
even if never dereferenced. Runs in the frontend only.
Level 2: Aggressive, quick, not too precise.
Unlike level 1, it only warns when an address is taken. Warns about
incomplete types. Runs in the frontend only.
-Level 3 (default for @option{-Wstrict-aliasing}):
-Should have very few false positives and few false
+Level 3 (default for @option{-Wstrict-aliasing}):
+Should have very few false positives and few false
negatives. Slightly slower than levels 1 or 2 when optimization is enabled.
Takes care of the common punn+dereference pattern in the frontend:
@code{*(int*)&some_float}.
-If optimization is enabled, it also runs in the backend, where it deals
+If optimization is enabled, it also runs in the backend, where it deals
with multiple statement cases using flow-sensitive points-to information.
Only warns when the converted pointer is dereferenced.
Does not warn about incomplete types.
the target type. For example, warn if a @code{const char *} is cast
to an ordinary @code{char *}.
+Also warn when making a cast which introduces a type qualifier in an
+unsafe way. For example, casting @code{char **} to @code{const char **}
+is unsafe, as in this example:
+
+@smallexample
+ /* p is char ** value. */
+ const char **q = (const char **) p;
+ /* Assignment of readonly string to const char * is OK. */
+ *q = "string";
+ /* Now char** pointer points to read-only memory. */
+ **p = 'b';
+@end smallexample
+
@item -Wcast-align
@opindex Wcast-align
@opindex Wno-cast-align
this warning is enabled by default. In C this warning is enabled by
@option{-Wall}.
+@item -Wjump-misses-init @r{(C, Objective-C only)}
+@opindex Wjump-misses-init
+@opindex Wno-jump-misses-init
+Warn if a @code{goto} statement or a @code{switch} statement jumps
+forward across the initialization of a variable, or jumps backward to a
+label after the variable has been initialized. This only warns about
+variables which are initialized when they are declared. This warning is
+only supported for C and Objective C; in C++ this sort of branch is an
+error in any case.
+
+@option{-Wjump-misses-init} is included in @option{-Wc++-compat}. It
+can be disabled with the @option{-Wno-jump-misses-init} option.
+
@item -Wsign-compare
@opindex Wsign-compare
@opindex Wno-sign-compare
@item -Wlong-long
@opindex Wlong-long
@opindex Wno-long-long
-Warn if @samp{long long} type is used. This is default. To inhibit
-the warning messages, use @option{-Wno-long-long}. Flags
-@option{-Wlong-long} and @option{-Wno-long-long} are taken into account
-only when @option{-pedantic} flag is used.
+Warn if @samp{long long} type is used. This is enabled by either
+@option{-pedantic} or @option{-Wtraditional} in ISO C90 and C++98
+modes. To inhibit the warning messages, use @option{-Wno-long-long}.
@item -Wvariadic-macros
@opindex Wvariadic-macros
This option is implied by @option{-pedantic}, and can be disabled with
@option{-Wno-overlength-strings}.
+
+@item -Wunsuffixed-float-constants @r{(C and Objective-C only)}
+@opindex Wunsuffixed-float-constants
+
+GCC will issue a warning for any floating constant that does not have
+a suffix. When used together with @option{-Wsystem-headers} it will
+warn about such constants in system header files. This can be useful
+when preparing code to use with the @code{FLOAT_CONST_DECIMAL64} pragma
+from the decimal floating-point extension to C99.
@end table
@node Debugging Options
refuse to read the program, and may cause assemblers other than the GNU
assembler (GAS) to fail with an error.
-@item -gdwarf-2
-@opindex gdwarf-2
-Produce debugging information in DWARF version 2 format (if that is
-supported). This is the format used by DBX on IRIX 6. With this
-option, GCC uses features of DWARF version 3 when they are useful;
-version 3 is upward compatible with version 2, but may still cause
-problems for older debuggers.
+@item -gdwarf-@var{version}
+@opindex gdwarf-@var{version}
+Produce debugging information in DWARF format (if that is
+supported). This is the format used by DBX on IRIX 6. The value
+of @var{version} may be either 2, 3 or 4; the default version is 2.
+
+Note that with DWARF version 2 some ports require, and will always
+use, some non-conflicting DWARF 3 extensions in the unwind tables.
+
+Version 4 may require GDB 7.0 and @option{-fvar-tracking-assignments}
+for maximum benefit.
+
+@item -gstrict-dwarf
+@opindex gstrict-dwarf
+Disallow using extensions of later DWARF standard version than selected
+with @option{-gdwarf-@var{version}}. On most targets using non-conflicting
+DWARF extensions from later standard versions is allowed.
+
+@item -gno-strict-dwarf
+@opindex gno-strict-dwarf
+Allow using extensions of later DWARF standard version than selected with
+@option{-gdwarf-@var{version}}.
@item -gvms
@opindex gvms
different from version 2), and it would have been too confusing. That
debug format is long obsolete, but the option cannot be changed now.
Instead use an additional @option{-g@var{level}} option to change the
-debug level for DWARF2.
+debug level for DWARF.
+
+@item -gtoggle
+@opindex gtoggle
+Turn off generation of debug info, if leaving out this option would have
+generated it, or turn it on at level 2 otherwise. The position of this
+argument in the command line does not matter, it takes effect after all
+other options are processed, and it does so only once, no matter how
+many times it is given. This is mainly intended to be used with
+@option{-fcompare-debug}.
+
+@item -fdump-final-insns@r{[}=@var{file}@r{]}
+@opindex fdump-final-insns
+Dump the final internal representation (RTL) to @var{file}. If the
+optional argument is omitted (or if @var{file} is @code{.}), the name
+of the dump file will be determined by appending @code{.gkd} to the
+compilation output file name.
+
+@item -fcompare-debug@r{[}=@var{opts}@r{]}
+@opindex fcompare-debug
+@opindex fno-compare-debug
+If no error occurs during compilation, run the compiler a second time,
+adding @var{opts} and @option{-fcompare-debug-second} to the arguments
+passed to the second compilation. Dump the final internal
+representation in both compilations, and print an error if they differ.
+
+If the equal sign is omitted, the default @option{-gtoggle} is used.
+
+The environment variable @env{GCC_COMPARE_DEBUG}, if defined, non-empty
+and nonzero, implicitly enables @option{-fcompare-debug}. If
+@env{GCC_COMPARE_DEBUG} is defined to a string starting with a dash,
+then it is used for @var{opts}, otherwise the default @option{-gtoggle}
+is used.
+
+@option{-fcompare-debug=}, with the equal sign but without @var{opts},
+is equivalent to @option{-fno-compare-debug}, which disables the dumping
+of the final representation and the second compilation, preventing even
+@env{GCC_COMPARE_DEBUG} from taking effect.
+
+To verify full coverage during @option{-fcompare-debug} testing, set
+@env{GCC_COMPARE_DEBUG} to say @samp{-fcompare-debug-not-overridden},
+which GCC will reject as an invalid option in any actual compilation
+(rather than preprocessing, assembly or linking). To get just a
+warning, setting @env{GCC_COMPARE_DEBUG} to @samp{-w%n-fcompare-debug
+not overridden} will do.
+
+@item -fcompare-debug-second
+@opindex fcompare-debug-second
+This option is implicitly passed to the compiler for the second
+compilation requested by @option{-fcompare-debug}, along with options to
+silence warnings, and omitting other options that would cause
+side-effect compiler outputs to files or to the standard output. Dump
+files and preserved temporary files are renamed so as to contain the
+@code{.gk} additional extension during the second compilation, to avoid
+overwriting those generated by the first.
+
+When this option is passed to the compiler driver, it causes the
+@emph{first} compilation to be skipped, which makes it useful for little
+other than debugging the compiler proper.
@item -feliminate-dwarf2-dups
@opindex feliminate-dwarf2-dups
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
@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 upperbound. @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},
@itemx -fdump-rtl-@var{pass}
@opindex d
Says to make debugging dumps during compilation at times specified by
-@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}. @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.
+@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.
Debug dumps can be enabled with a @option{-fdump-rtl} switch or some
@option{-d} option @var{letters}. Here are the possible
@opindex fdump-rtl-ce3
@option{-fdump-rtl-ce1}, @option{-fdump-rtl-ce2}, and
@option{-fdump-rtl-ce3} enable dumping after the three
-if conversion passes.
+if conversion passes.
@itemx -fdump-rtl-cprop_hardreg
@opindex fdump-rtl-cprop_hardreg
@item -fdump-rtl-seqabstr
@opindex fdump-rtl-seqabstr
-Dump after common sequence discovery.
+Dump after common sequence discovery.
@item -fdump-rtl-shorten
@opindex fdump-rtl-shorten
invocations with different options, in particular with and without
@option{-g}.
+@item -fdump-unnumbered-links
+@opindex fdump-unnumbered-links
+When doing debugging dumps (see @option{-d} option above), suppress
+instruction numbers for the links to the previous and next instructions
+in a sequence.
+
@item -fdump-translation-unit @r{(C++ only)}
@itemx -fdump-translation-unit-@var{options} @r{(C++ only)}
@opindex fdump-translation-unit
Dump a representation of the tree structure for the entire translation
unit to a file. The file name is made by appending @file{.tu} to the
-source file name. If the @samp{-@var{options}} form is used, @var{options}
+source file name, and the file is created in the same directory as the
+output file. If the @samp{-@var{options}} form is used, @var{options}
controls the details of the dump as described for the
@option{-fdump-tree} options.
@itemx -fdump-class-hierarchy-@var{options} @r{(C++ only)}
@opindex fdump-class-hierarchy
Dump a representation of each class's hierarchy and virtual function
-table layout to a file. The file name is made by appending @file{.class}
-to the source file name. If the @samp{-@var{options}} form is used,
-@var{options} controls the details of the dump as described for the
-@option{-fdump-tree} options.
+table layout to a file. The file name is made by appending
+@file{.class} to the source file name, and the file is created in the
+same directory as the output file. If the @samp{-@var{options}} form
+is used, @var{options} controls the details of the dump as described
+for the @option{-fdump-tree} options.
@item -fdump-ipa-@var{switch}
@opindex fdump-ipa
Control the dumping at various stages of inter-procedural analysis
-language tree to a file. The file name is generated by appending a switch
-specific suffix to the source file name. The following dumps are possible:
+language tree to a file. The file name is generated by appending a
+switch specific suffix to the source file name, and the file is created
+in the same directory as the output file. The following dumps are
+possible:
@table @samp
@item all
@end table
@item -fdump-statistics-@var{option}
-@opindex -fdump-statistics
+@opindex fdump-statistics
Enable and control dumping of pass statistics in a separate file. The
-file name is generated by appending a suffix ending in @samp{.statistics}
-to the source file name. If the @samp{-@var{option}} form is used,
-@samp{-stats} will cause counters to be summed over the whole compilation unit
-while @samp{-details} will dump every event as the passes generate them.
-The default with no option is to sum counters for each function compiled.
+file name is generated by appending a suffix ending in
+@samp{.statistics} to the source file name, and the file is created in
+the same directory as the output file. If the @samp{-@var{option}}
+form is used, @samp{-stats} will cause counters to be summed over the
+whole compilation unit while @samp{-details} will dump every event as
+the passes generate them. The default with no option is to sum
+counters for each function compiled.
@item -fdump-tree-@var{switch}
@itemx -fdump-tree-@var{switch}-@var{options}
@opindex fdump-tree
Control the dumping at various stages of processing the intermediate
-language tree to a file. The file name is generated by appending a switch
-specific suffix to the source file name. If the @samp{-@var{options}}
-form is used, @var{options} is a list of @samp{-} separated options that
-control the details of the dump. Not all options are applicable to all
-dumps, those which are not meaningful will be ignored. The following
-options are available
+language tree to a file. The file name is generated by appending a
+switch specific suffix to the source file name, and the file is
+created in the same directory as the output file. If the
+@samp{-@var{options}} form is used, @var{options} is a list of
+@samp{-} separated options that control the details of the dump. Not
+all options are applicable to all dumps, those which are not
+meaningful will be ignored. The following options are available
@table @samp
@item address
Print the address of each node. Usually this is not meaningful as it
changes according to the environment and source file. Its primary use
is for tying up a dump file with a debug environment.
+@item asmname
+If @code{DECL_ASSEMBLER_NAME} has been set for a given decl, use that
+in the dump instead of @code{DECL_NAME}. Its primary use is ease of
+use working backward from mangled names in the assembly file.
@item slim
Inhibit dumping of members of a scope or body of a function merely
because that scope has been reached. Only dump such items when they
Enable showing the unique ID (@code{DECL_UID}) for each variable.
@item verbose
Enable showing the tree dump for each statement.
+@item eh
+Enable showing the EH region number holding each statement.
@item all
Turn on all options, except @option{raw}, @option{slim}, @option{verbose}
and @option{lineno}.
@table @samp
@item original
+@opindex fdump-tree-original
Dump before any tree based optimization, to @file{@var{file}.original}.
@item optimized
+@opindex fdump-tree-optimized
Dump after all tree based optimization, to @file{@var{file}.optimized}.
@item gimple
that @option{-fdump-tree-vect-details} uses.
@item -frandom-seed=@var{string}
-@opindex frandom-string
+@opindex frandom-seed
This option provides a seed that GCC uses when it would otherwise use
random numbers. It is used to generate certain symbol names
that have to be different in every compiled file. It is also used to
@file{dir/xbar.s}, @file{dir2/yfoobar.i}, @file{dir2/yfoobar.s}, and
@file{dir2/yfoobar.o}.
-@item -time
+@item -time@r{[}=@var{file}@r{]}
@opindex time
Report the CPU time taken by each subprocess in the compilation
sequence. For C source files, this is the compiler proper and assembler
-(plus the linker if linking is done). The output looks like this:
+(plus the linker if linking is done).
+
+Without the specification of an output file, the output looks like this:
@smallexample
# cc1 0.12 0.01
time spent executing operating system routines on behalf of the program.
Both numbers are in seconds.
+With the specification of an output file, the output is appended to the
+named file, and it looks like this:
+
+@smallexample
+0.12 0.01 cc1 @var{options}
+0.00 0.01 as @var{options}
+@end smallexample
+
+The ``user time'' and the ``system time'' are moved before the program
+name, and the options passed to the program are displayed, so that one
+can later tell what file was being compiled, and with which options.
+
@item -fvar-tracking
@opindex fvar-tracking
Run variable tracking pass. It computes where variables are stored at each
@option{-O}, @option{-O2}, @dots{}), debugging information (@option{-g}) and
the debug info format supports it.
+@item -fvar-tracking-assignments
+@opindex fvar-tracking-assignments
+@opindex fno-var-tracking-assignments
+Annotate assignments to user variables early in the compilation and
+attempt to carry the annotations over throughout the compilation all the
+way to the end, in an attempt to improve debug information while
+optimizing. Use of @option{-gdwarf-4} is recommended along with it.
+
+It can be enabled even if var-tracking is disabled, in which case
+annotations will be created and maintained, but discarded at the end.
+
+@item -fvar-tracking-assignments-toggle
+@opindex fvar-tracking-assignments-toggle
+@opindex fno-var-tracking-assignments-toggle
+Toggle @option{-fvar-tracking-assignments}, in the same way that
+@option{-gtoggle} toggles @option{-g}.
+
@item -print-file-name=@var{library}
@opindex print-file-name
Print the full absolute name of the library file @var{library} that
@samp{-}, without spaces between multiple switches. This is supposed to
ease shell-processing.
+@item -print-multi-os-directory
+@opindex print-multi-os-directory
+Print the path to OS libraries for the selected
+multilib, relative to some @file{lib} subdirectory. If OS libraries are
+present in the @file{lib} subdirectory and no multilibs are used, this is
+usually just @file{.}, if OS libraries are present in @file{lib@var{suffix}}
+sibling directories this prints e.g.@: @file{../lib64}, @file{../lib} or
+@file{../lib32}, or if OS libraries are present in @file{lib/@var{subdir}}
+subdirectories it prints e.g.@: @file{amd64}, @file{sparcv9} or @file{ev6}.
+
@item -print-prog-name=@var{program}
@opindex print-prog-name
Like @option{-print-file-name}, but searches for a program such as @samp{cpp}.
Not all optimizations are controlled directly by a flag. Only
optimizations that have a flag are listed in this section.
-Depending on the target and how GCC was configured, a slightly different
-set of optimizations may be enabled at each @option{-O} level than
-those listed here. You can invoke GCC with @samp{-Q --help=optimizers}
+Most of the optimizations are not enabled if a @option{-O} level is not set on
+the command line, even if individual optimization flags are specified.
+
+Depending on the target and how GCC was configured, a slightly different
+set of optimizations may be enabled at each @option{-O} level than
+those listed here. You can invoke GCC with @samp{-Q --help=optimizers}
to find out the exact set of optimizations that are enabled at each level.
@xref{Overall Options}, for examples.
-fguess-branch-probability @gol
-fif-conversion2 @gol
-fif-conversion @gol
--finline-small-functions @gol
-fipa-pure-const @gol
-fipa-reference @gol
-fmerge-constants
-ftree-dce @gol
-ftree-dominator-opts @gol
-ftree-dse @gol
+-ftree-forwprop @gol
-ftree-fre @gol
+-ftree-phiprop @gol
-ftree-sra @gol
+-ftree-pta @gol
-ftree-ter @gol
-funit-at-a-time}
-fdelete-null-pointer-checks @gol
-fexpensive-optimizations @gol
-fgcse -fgcse-lm @gol
+-finline-small-functions @gol
-findirect-inlining @gol
+-fipa-sra @gol
-foptimize-sibling-calls @gol
-fpeephole2 @gol
-fregmove @gol
is active, two passes are performed and the second is scheduled after
loop unrolling.
-This option is enabled by default at optimization levels @option{-O2},
-@option{-O3}, @option{-Os}.
+This option is enabled by default at optimization levels @option{-O},
+@option{-O2}, @option{-O3}, @option{-Os}.
@item -fomit-frame-pointer
@opindex fomit-frame-pointer
Enabled by default.
+@item -fipa-sra
+@opindex fipa-sra
+Perform interprocedural scalar replacement of aggregates, removal of
+unused parameters and replacement of parameters passed by reference
+by parameters passed by value.
+
+Enabled at levels @option{-O2}, @option{-O3} and @option{-Os}.
+
@item -finline-limit=@var{n}
@opindex finline-limit
By default, GCC limits the size of functions that can be inlined. This flag
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
+loop invariants. Usage of this option usually results in generation
+of faster and smaller code on machines with big register files (>= 32
+registers) but it can slow compiler down.
+
+This option is enabled at level @option{-O3} for some targets.
+
@item -fno-ira-share-save-slots
@opindex fno-ira-share-save-slots
Switch off sharing stack slots used for saving call used hard
enabled by default when scheduling before register allocation, i.e.@:
with @option{-fschedule-insns} or at @option{-O2} or higher.
+@item -fsched-pressure
+@opindex fsched-pressure
+Enable register pressure sensitive insn scheduling before the register
+allocation. This only makes sense when scheduling before register
+allocation is enabled, i.e.@: with @option{-fschedule-insns} or at
+@option{-O2} or higher. Usage of this option can improve the
+generated code and decrease its size by preventing register pressure
+increase above the number of available hard registers and as a
+consequence register spills in the register allocation.
+
@item -fsched-spec-load
@opindex fsched-spec-load
Allow speculative motion of some load instructions. This only makes
This only makes sense when scheduling after register allocation, i.e.@: with
@option{-fschedule-insns2} or at @option{-O2} or higher.
+@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}
+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}
+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}
+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
+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
+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
+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
+at @option{-O2} or higher.
+
@item -fsched2-use-traces
@opindex fsched2-use-traces
Use @option{-fsched2-use-superblocks} algorithm when scheduling after register
sense when scheduling after register allocation, i.e.@: with
@option{-fschedule-insns2} or at @option{-O2} or higher.
-@item -fsee
-@opindex fsee
-Eliminate redundant sign extension instructions and move the non-redundant
-ones to optimal placement using lazy code motion (LCM).
-
@item -freschedule-modulo-scheduled-loops
@opindex freschedule-modulo-scheduled-loops
The modulo scheduling comes before the traditional scheduling, if a loop
@item -fsel-sched-pipelining
@opindex fsel-sched-pipelining
-Enable software pipelining of innermost loops during selective scheduling.
-This option has no effect until one of @option{-fselective-scheduling} or
+Enable software pipelining of innermost loops during selective scheduling.
+This option has no effect until one of @option{-fselective-scheduling} or
@option{-fselective-scheduling2} is turned on.
@item -fsel-sched-pipelining-outer-loops
Perform partial redundancy elimination (PRE) on trees. This flag is
enabled by default at @option{-O2} and @option{-O3}.
+@item -ftree-forwprop
+@opindex ftree-forwprop
+Perform forward propagation on trees. This flag is enabled by default
+at @option{-O} and higher.
+
@item -ftree-fre
@opindex ftree-fre
Perform full redundancy elimination (FRE) on trees. The difference
This analysis is faster than PRE, though it exposes fewer redundancies.
This flag is enabled by default at @option{-O} and higher.
+@item -ftree-phiprop
+@opindex ftree-phiprop
+Perform hoisting of loads from conditional pointers on trees. This
+pass is enabled by default at @option{-O} and higher.
+
@item -ftree-copy-prop
@opindex ftree-copy-prop
Perform copy propagation on trees. This pass eliminates unnecessary
@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
+Perform structure reorganization optimization, that change C-like structures
+layout in order to better utilize spatial locality. This transformation is
+affective for programs containing arrays of structures. Available in two
compilation modes: profile-based (enabled with @option{-fprofile-generate})
or static (which uses built-in heuristics). Require @option{-fipa-type-escape}
to provide the safety of this transformation. It works only in whole program
@opindex fipa-cp
Perform interprocedural constant propagation.
This optimization analyzes the program to determine when values passed
-to functions are constants and then optimizes accordingly.
+to functions are constants and then optimizes accordingly.
This optimization can substantially increase performance
if the application has constants passed to functions.
This flag is enabled by default at @option{-O2}, @option{-Os} and @option{-O3}.
@item -fipa-matrix-reorg
@opindex fipa-matrix-reorg
Perform matrix flattening and transposing.
-Matrix flattening tries to replace a m-dimensional matrix
-with its equivalent n-dimensional matrix, where n < m.
+Matrix flattening tries to replace an @math{m}-dimensional matrix
+with its equivalent @math{n}-dimensional matrix, where @math{n < m}.
This reduces the level of indirection needed for accessing the elements
of the matrix. The second optimization is matrix transposing that
attempts to change the order of the matrix's dimensions in order to
improve cache locality.
-Both optimizations need the @option{-fwhole-program} flag.
+Both optimizations need the @option{-fwhole-program} flag.
Transposing is enabled only if profiling information is available.
-
@item -ftree-sink
@opindex ftree-sink
Perform forward store motion on trees. This flag is
@item -ftree-builtin-call-dce
@opindex ftree-builtin-call-dce
-Perform conditional dead code elimination (DCE) for calls to builtin functions
-that may set @code{errno} but are otherwise side-effect free. This flag is
-enabled by default at @option{-O2} and higher if @option{-Os} is not also
+Perform conditional dead code elimination (DCE) for calls to builtin functions
+that may set @code{errno} but are otherwise side-effect free. This flag is
+enabled by default at @option{-O2} and higher if @option{-Os} is not also
specified.
@item -ftree-dominator-opts
@item -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
+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
original loop within a strip. For example, given a loop like:
@smallexample
DO I = 1, N
and @option{--with-cloog} to enable the Graphite loop transformation
infrastructure.
+@item -fgraphite-identity
+@opindex fgraphite-identity
+Enable the identity transformation for graphite. For every SCoP we generate
+the polyhedral representation and transform it back to gimple. Using
+@option{-fgraphite-identity} we can check the costs or benefits of the
+GIMPLE -> GRAPHITE -> GIMPLE transformation. Some minimal optimizations
+are also performed by the code generator CLooG, like index splitting and
+dead code elimination in loops.
+
+@item -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
+profitable to parallelize the loops.
+
@item -fcheck-data-deps
@opindex fcheck-data-deps
Compare the results of several data dependence analyzers. This option
implies @option{-pthread}, and thus is only supported on targets
that have support for @option{-pthread}.
+@item -ftree-pta
+@opindex ftree-pta
+Perform function-local points-to analysis on trees. This flag is
+enabled by default at @option{-O} and higher.
+
@item -ftree-sra
@opindex ftree-sra
Perform scalar replacement of aggregates. This pass replaces structure
@item -fstrict-aliasing
@opindex fstrict-aliasing
-Allows the compiler to assume the strictest aliasing rules applicable to
+Allow the compiler to assume the strictest aliasing rules applicable to
the language being compiled. For C (and C++), this activates
optimizations based on the type of expressions. In particular, an
object of one type is assumed never to reside at the same address as an
@};
int f() @{
- a_union t;
+ union a_union t;
t.d = 3.0;
return t.i;
@}
implementation}. However, this code might not:
@smallexample
int f() @{
- a_union t;
+ union a_union t;
int* ip;
t.d = 3.0;
ip = &t.i;
@item -fwhole-program
@opindex fwhole-program
-Assume that the current compilation unit represents whole program being
+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 a affect gets more aggressively optimized by interprocedural optimizers.
-While this option is equivalent to proper use of @code{static} keyword for
-programs consisting of single file, in combination with option
-@option{--combine} this flag can be used to compile most of smaller scale C
-programs since the functions and variables become local for the whole combined
-compilation unit, not for the single source file itself.
+and in effect are optimized more aggressively by interprocedural optimizers.
+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
+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
+@opindex flto
+This option runs the standard link-time optimizer. When invoked
+with source code, it generates GIMPLE (one of GCC's internal
+representations) and writes it to special ELF sections in the object
+file. When the object files are linked together, all the function
+bodies are read from these ELF sections and instantiated as if they
+had been part of the same translation unit.
+
+To use the link-timer optimizer, @option{-flto} needs to be specified at
+compile time and during the final link. For example,
+
+@smallexample
+gcc -c -O2 -flto foo.c
+gcc -c -O2 -flto bar.c
+gcc -o myprog -flto -O2 foo.o bar.o
+@end smallexample
+
+The first two invocations to GCC will save a bytecode representation
+of GIMPLE into special ELF sections inside @file{foo.o} and
+@file{bar.o}. The final invocation will read the GIMPLE bytecode from
+@file{foo.o} and @file{bar.o}, merge the two files into a single
+internal image, and compile the result as usual. Since both
+@file{foo.o} and @file{bar.o} are merged into a single image, this
+causes all the inter-procedural analyses and optimizations in GCC to
+work across the two files as if they were a single one. This means,
+for example, that the inliner will be able to inline functions in
+@file{bar.o} into functions in @file{foo.o} and vice-versa.
+
+Another (simpler) way to enable link-time optimization is,
+
+@smallexample
+gcc -o myprog -flto -O2 foo.c bar.c
+@end smallexample
+
+The above will generate bytecode for @file{foo.c} and @file{bar.c},
+merge them together into a single GIMPLE representation and optimize
+them as usual to produce @file{myprog}.
+
+The only important thing to keep in mind is that to enable link-time
+optimizations the @option{-flto} flag needs to be passed to both the
+compile and the link commands.
+
+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
+object files with LTO information can be linked as a normal object
+file. So, in the previous example, if the final link is done with
+
+@smallexample
+gcc -o myprog foo.o bar.o
+@end smallexample
+
+The only difference will be that no inter-procedural optimizations
+will be applied to produce @file{myprog}. The two object files
+@file{foo.o} and @file{bar.o} will be simply sent to the regular
+linker.
+
+Additionally, the optimization flags used to compile individual files
+are not necessarily related to those used at link-time. For instance,
+
+@smallexample
+gcc -c -O0 -flto foo.c
+gcc -c -O0 -flto bar.c
+gcc -o myprog -flto -O3 foo.o bar.o
+@end smallexample
+
+This will produce individual object files with unoptimized assembler
+code, but the resulting binary @file{myprog} will be optimized at
+@option{-O3}. Now, if the final binary is generated without
+@option{-flto}, then @file{myprog} will not be optimized.
+
+When producing the final binary with @option{-flto}, GCC will only
+apply link-time optimizations to those files that contain bytecode.
+Therefore, you can mix and match object files and libraries with
+GIMPLE bytecodes and final object code. GCC will automatically select
+which files to optimize in LTO mode and which files to link without
+further processing.
+
+There are some code generation flags that GCC will preserve when
+generating bytecodes, as they need to be used during the final link
+stage. Currently, the following options are saved into the GIMPLE
+bytecode files: @option{-fPIC}, @option{-fcommon} and all the
+@option{-m} target flags.
+
+At link time, these options are read-in and reapplied. Note that the
+current implementation makes no attempt at recognizing conflicting
+values for these options. If two or more files have a conflicting
+value (e.g., one file is compiled with @option{-fPIC} and another
+isn't), the compiler will simply use the last value read from the
+bytecode files. It is recommended, then, that all the files
+participating in the same link be compiled with the same options.
+
+Another feature of LTO is that it is possible to apply interprocedural
+optimizations on files written in different languages. This requires
+some support in the language front end. Currently, the C, C++ and
+Fortran front ends are capable of emitting GIMPLE bytecodes, so
+something like this should work
-This option is not supported for Fortran programs.
+@smallexample
+gcc -c -flto foo.c
+g++ -c -flto bar.cc
+gfortran -c -flto baz.f90
+g++ -o myprog -flto -O3 foo.o bar.o baz.o -lgfortran
+@end smallexample
+
+Notice that the final link is done with @command{g++} to get the C++
+runtime libraries and @option{-lgfortran} is added to get the Fortran
+runtime libraries. In general, when mixing languages in LTO mode, you
+should use the same link command used when mixing languages in a
+regular (non-LTO) compilation. This means that if your build process
+was mixing languages before, all you need to add is @option{-flto} to
+all the compile and link commands.
+
+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{-use-linker-plugin} at
+link-time:
+
+@smallexample
+gcc -o myprog -O2 -flto -use-linker-plugin a.o b.o -lfoo
+@end smallexample
+
+With the linker plugin enabled, @command{gold} 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{-use-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.
+
+Regarding portability: the current implementation of LTO makes no
+attempt at generating bytecode that can be ported between different
+types of hosts. The bytecode files are versioned and there is a
+strict version check, so bytecode files generated in one version of
+GCC will not work with an older/newer version of GCC.
+
+This option is disabled by default.
+
+@item -fwhopr
+@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.
+
+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-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
+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.
+
+@item -flto-report
+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}).
+
+Disabled by default.
+
+@item -use-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.
+
+Disabled by default.
@item -fcprop-registers
@opindex fcprop-registers
Set the directory to search 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 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.
@var{name} are given in the following table:
@table @gcctabopt
-@item sra-max-structure-size
-The maximum structure size, in bytes, at which the scalar replacement
-of aggregates (SRA) optimization will perform block copies. The
-default value, 0, implies that GCC will select the most appropriate
-size itself.
-
-@item sra-field-structure-ratio
-The threshold ratio (as a percentage) between instantiated fields and
-the complete structure size. We say that if the ratio of the number
-of bytes in instantiated fields to the number of bytes in the complete
-structure exceeds this parameter, then block copies are not used. The
-default is 75.
-
@item struct-reorg-cold-struct-ratio
The threshold ratio (as a percentage) between a structure frequency
and the frequency of the hottest structure in the program. This parameter
is used by struct-reorg optimization enabled by @option{-fipa-struct-reorg}.
-We say that if the ratio of a structure frequency, calculated by profiling,
-to the hottest structure frequency in the program is less than this
+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.
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 450.
+The default value is 300.
@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 90.
+The default value is 50.
@item large-function-insns
The limit specifying really large functions. For functions larger than this
whose probability exceeds given threshold (in percents). The default value is
10.
-@item inline-call-cost
-Specify cost of call instruction relative to simple arithmetics operations
-(having cost of 1). Increasing this cost disqualifies inlining of non-leaf
-functions and at the same time increases size of leaf function that is believed to
-reduce function size by being inlined. In effect it increases amount of
-inlining for code having large abstraction penalty (many functions that just
-pass the arguments to other functions) and decrease inlining for code with low
-abstraction penalty. The default value is 12.
+@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.
+
+@item max-early-inliner-iterations
+@itemx max-early-inliner-iterations
+Limit of iterations of early inliner. This basically bounds number of nested
+indirect calls early inliner can resolve. Deeper chains are still handled by
+late inlining.
@item min-vect-loop-bound
The minimum number of iterations under which a loop will not get vectorized
The default value is 50.
@item selsched-max-sched-times
-The maximum number of times that an instruction will be scheduled during
-selective scheduling. This is the limit on the number of iterations
+The maximum number of times that an instruction will be scheduled during
+selective scheduling. This is the limit on the number of iterations
through which the instruction may be pipelined. The default value is 2.
@item selsched-max-insns-to-rename
@item l2-cache-size
The size of L2 cache, in kilobytes.
+@item min-insn-to-prefetch-ratio
+The minimum ratio between the number of instructions and the
+number of prefetches to enable prefetching in a loop with an
+unknown trip count.
+
+@item prefetch-min-insn-to-mem-ratio
+The minimum ratio between the number of instructions and the
+number of memory references to enable prefetching in a loop.
+
@item use-canonical-types
Whether the compiler should use the ``canonical'' type system. By
default, this should always be 1, which uses a more efficient internal
algorithm do not use pseudo-register conflicts. The default value of
the parameter is 2000.
+@item ira-loop-reserved-regs
+IRA can be used to evaluate more accurate register pressure in loops
+for decision to move loop invariants (see @option{-O3}). The number
+of available registers reserved for some other purposes is described
+by this parameter. The default value of the parameter is 2 which is
+minimal number of registers needed for execution of typical
+instruction. This value is the best found from numerous experiments.
+
@item loop-invariant-max-bbs-in-loop
Loop invariant motion can be very expensive, both in compile time and
in amount of needed compile time memory, with very large loops. Loops
motion optimization performed on them. The default value of the
parameter is 1000 for -O1 and 10000 for -O2 and above.
+@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
+@option{-fvar-tracking-assignments}, but debug insns may get
+(non-overlapping) uids above it if the reserved range is exhausted.
+
+@item ipa-sra-ptr-growth-factor
+IPA-SRA will replace a pointer to an aggregate with one or more new
+parameters only when their cumulative size is less or equal to
+@option{ipa-sra-ptr-growth-factor} times the size of the original
+pointer parameter.
+
@end table
@end table
compilation.
@table @gcctabopt
+@item -Wp,@var{option}
@opindex Wp
You can use @option{-Wp,@var{option}} to bypass the compiler driver
and pass @var{option} directly through to the preprocessor. If
options instead.
@item -Xpreprocessor @var{option}
-@opindex preprocessor
+@opindex Xpreprocessor
Pass @var{option} as an option to the preprocessor. You can use this to
supply system-specific preprocessor options which GCC does not know how to
recognize.
@item -nodefaultlibs
@opindex nodefaultlibs
Do not use the standard system libraries when linking.
-Only the libraries you specify will be passed to the linker.
+Only the libraries you specify will be passed to the linker, options
+specifying linkage of the system libraries, such as @code{-static-libgcc}
+or @code{-shared-libgcc}, will be ignored.
The standard startup files are used normally, unless @option{-nostartfiles}
is used. The compiler may generate calls to @code{memcmp},
@code{memset}, @code{memcpy} and @code{memmove}.
@opindex nostdlib
Do not use the standard system startup files or libraries when linking.
No startup files and only the libraries you specify will be passed to
-the linker. The compiler may generate calls to @code{memcmp}, @code{memset},
+the linker, options specifying linkage of the system libraries, such as
+@code{-static-libgcc} or @code{-shared-libgcc}, will be ignored.
+The compiler may generate calls to @code{memcmp}, @code{memset},
@code{memcpy} and @code{memmove}.
These entries are usually resolved by entries in
libc. These entry points should be supplied through some other
@option{-shared-libgcc}, such that it is linked with the shared
@file{libgcc}.
+@item -static-libstdc++
+When the @command{g++} program is used to link a C++ program, it will
+normally automatically link against @option{libstdc++}. If
+@file{libstdc++} is available as a shared library, and the
+@option{-static} option is not used, then this will link against the
+shared version of @file{libstdc++}. That is normally fine. However, it
+is sometimes useful to freeze the version of @file{libstdc++} used by
+the program without going all the way to a fully static link. The
+@option{-static-libstdc++} option directs the @command{g++} driver to
+link @file{libstdc++} statically, without necessarily linking other
+libraries statically.
+
@item -symbolic
@opindex symbolic
Bind references to global symbols when building a shared object. Warn
@cindex linker script
Use @var{script} as the linker script. This option is supported by most
systems using the GNU linker. On some targets, such as bare-board
-targets without an operating system, the @option{-T} option may be required
+targets without an operating system, the @option{-T} option may be required
when linking to avoid references to undefined symbols.
@item -Xlinker @var{option}
@option{-Xlinker "-assert definitions"}, because this passes the entire
string as a single argument, which is not what the linker expects.
-When using the GNU linker, it is usually more convenient to pass
+When using the GNU linker, it is usually more convenient to pass
arguments to linker options using the @option{@var{option}=@var{value}}
syntax than as separate arguments. For example, you can specify
@samp{-Xlinker -Map=output.map} rather than
@opindex Wl
Pass @var{option} as an option to the linker. If @var{option} contains
commas, it is split into multiple options at the commas. You can use this
-syntax to pass an argument to the option.
+syntax to pass an argument to the option.
For example, @samp{-Wl,-Map,output.map} passes @samp{-Map output.map} to the
linker. When using the GNU linker, you can also get the same effect with
@samp{-Wl,-Map=output.map}.
@item %s
Current argument is the name of a library or startup file of some sort.
Search for that file in a standard list of directories and substitute
-the full name found.
+the full name found. The current working directory is included in the
+list of directories scanned.
+
+@item %T
+Current argument is the name of a linker script. Search for that file
+in the current list of directories to scan for libraries. If the file
+is located insert a @option{--script} option into the command line
+followed by the full path name found. If the file is not found then
+generate an error message. Note: the current working directory is not
+searched.
@item %e@var{str}
Print @var{str} as an error message. @var{str} is terminated by a newline.
* i386 and x86-64 Options::
* i386 and x86-64 Windows Options::
* IA-64 Options::
+* IA-64/VMS Options::
* M32C Options::
* M32R/D Options::
* M680x0 Options::
* M68hc1x Options::
* MCore Options::
+* MeP Options::
* MIPS Options::
* MMIX Options::
* MN10300 Options::
* picoChip Options::
* PowerPC Options::
* RS/6000 and PowerPC Options::
+* RX Options::
* S/390 and zSeries Options::
* Score Options::
* SH Options::
Specifies which floating-point ABI to use. Permissible values
are: @samp{soft}, @samp{softfp} and @samp{hard}.
-Specifying @samp{soft} causes GCC to generate output containing
+Specifying @samp{soft} causes GCC to generate output containing
library calls for floating-point operations.
-@samp{softfp} allows the generation of code using hardware floating-point
-instructions, but still uses the soft-float calling conventions.
-@samp{hard} allows generation of floating-point instructions
+@samp{softfp} allows the generation of code using hardware floating-point
+instructions, but still uses the soft-float calling conventions.
+@samp{hard} allows generation of floating-point instructions
and uses FPU-specific calling conventions.
-Using @option{-mfloat-abi=hard} with VFP coprocessors is not supported.
-Use @option{-mfloat-abi=softfp} with the appropriate @option{-mfpu} option
-to allow the compiler to generate code that makes use of the hardware
-floating-point capabilities for these CPUs.
-
The default depends on the specific target configuration. Note that
the hard-float and soft-float ABIs are not link-compatible; you must
compile your entire program with the same ABI, and link with a
@samp{arm10tdmi}, @samp{arm1020t}, @samp{arm1026ej-s},
@samp{arm10e}, @samp{arm1020e}, @samp{arm1022e},
@samp{arm1136j-s}, @samp{arm1136jf-s}, @samp{mpcore}, @samp{mpcorenovfp},
-@samp{arm1156t2-s}, @samp{arm1176jz-s}, @samp{arm1176jzf-s},
+@samp{arm1156t2-s}, @samp{arm1156t2f-s}, @samp{arm1176jz-s}, @samp{arm1176jzf-s},
@samp{cortex-a8}, @samp{cortex-a9},
@samp{cortex-r4}, @samp{cortex-r4f}, @samp{cortex-m3},
@samp{cortex-m1},
+@samp{cortex-m0},
@samp{xscale}, @samp{iwmmxt}, @samp{iwmmxt2}, @samp{ep9312}.
@item -mtune=@var{name}
@opindex mfp
This specifies what floating point hardware (or hardware emulation) is
available on the target. Permissible names are: @samp{fpa}, @samp{fpe2},
-@samp{fpe3}, @samp{maverick}, @samp{vfp}, @samp{vfpv3}, @samp{vfpv3-d16} and
-@samp{neon}. @option{-mfp} and @option{-mfpe}
+@samp{fpe3}, @samp{maverick}, @samp{vfp}, @samp{vfpv3}, @samp{vfpv3-d16},
+@samp{neon}, and @samp{neon-fp16}. @option{-mfp} and @option{-mfpe}
are synonyms for @option{-mfpu}=@samp{fpe}@var{number}, for compatibility
with older versions of GCC@.
If @option{-msoft-float} is specified this specifies the format of
floating point values.
+@item -mfp16-format=@var{name}
+@opindex mfp16-format
+Specify the format of the @code{__fp16} half-precision floating-point type.
+Permissible names are @samp{none}, @samp{ieee}, and @samp{alternative};
+the default is @samp{none}, in which case the @code{__fp16} type is not
+defined. @xref{Half-Precision}, for more information.
+
@item -mstructure-size-boundary=@var{n}
@opindex mstructure-size-boundary
The size of all structures and unions will be rounded up to a multiple
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
+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}
+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}.
@item -mtpcs-frame
Gives all externally visible functions in the file being compiled an ARM
instruction set header which switches to Thumb mode before executing the
rest of the function. This allows these functions to be called from
-non-interworking code.
+non-interworking code. This option is not valid in AAPCS configurations
+because interworking is enabled by default.
@item -mcaller-super-interworking
@opindex mcaller-super-interworking
Allows calls via function pointers (including virtual functions) to
execute correctly regardless of whether the target code has been
compiled for interworking or not. There is a small overhead in the cost
-of executing a function pointer if this option is enabled.
+of executing a function pointer if this option is enabled. This option
+is not valid in AAPCS configurations because interworking is enabled
+by default.
@item -mtp=@var{name}
@opindex mtp
memory space (MCU types: atmega16, atmega161, atmega163, atmega32, atmega323,
atmega64, atmega128, at43usb355, at94k).
-@item -msize
-@opindex msize
-Output instruction sizes to the asm file.
-
-@item -minit-stack=@var{N}
-@opindex minit-stack
-Specify the initial stack address, which may be a symbol or numeric value,
-@samp{__stack} is the default.
-
@item -mno-interrupts
@opindex mno-interrupts
Generated code is not compatible with hardware interrupts.
@item -mint8
@opindex mint8
Assume int to be 8 bit integer. This affects the sizes of all types: A
-char will be 1 byte, an int will be 1 byte, an long will be 2 bytes
+char will be 1 byte, an int will be 1 byte, a long will be 2 bytes
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.
@samp{bf527}, @samp{bf531}, @samp{bf532}, @samp{bf533},
@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}.
The optional @var{sirevision} specifies the silicon revision of the target
Blackfin processor. Any workarounds available for the targeted silicon revision
and link scripts will be used to support Core B. This option
defines @code{__BFIN_COREB}. When this option is used, coreb_main
should be used instead of main. It must be used with
-@option{-mmulticore}.
+@option{-mmulticore}.
@item -msdram
@opindex msdram
The Darwin tools vary in their behavior when presented with an ISA
mismatch. The assembler, @file{as}, will only permit instructions to
be used that are valid for the subtype of the file it is generating,
-so you cannot put 64-bit instructions in an @samp{ppc750} object file.
+so you cannot put 64-bit instructions in a @samp{ppc750} object file.
The linker for shared libraries, @file{/usr/bin/libtool}, will fail
and print an error if asked to create a shared library with a less
restrictive subtype than its input files (for instance, trying to put
@opindex mvms-return-codes
Return VMS condition codes from main. The default is to return POSIX
style condition (e.g.@: error) codes.
+
+@item -mdebug-main=@var{prefix}
+@opindex mdebug-main=@var{prefix}
+Flag the first routine whose name starts with @var{prefix} as the main
+routine for the debugger.
+
+@item -mmalloc64
+@opindex mmalloc64
+Default to 64bit memory allocation routines.
@end table
@node FR30 Options
command line.
@item -mTLS
-@opindex TLS
+@opindex mTLS
Assume a large TLS segment when generating thread-local code.
@item -mtls
-@opindex tls
+@opindex mtls
Do not assume a large TLS segment when generating thread-local code.
options are available under HP-UX and HI-UX@.
@item -mgnu-ld
-@opindex gnu-ld
+@opindex mgnu-ld
Use GNU ld specific options. This passes @option{-shared} to ld when
building a shared library. It is the default when GCC is configured,
explicitly or implicitly, with the GNU linker. This option does not
on the 64 bit HP-UX GCC, i.e.@: configured with @samp{hppa*64*-*-hpux*}.
@item -mhp-ld
-@opindex hp-ld
+@opindex mhp-ld
Use HP ld specific options. This passes @option{-b} to ld when building
a shared library and passes @option{+Accept TypeMismatch} to ld on all
links. It is the default when GCC is configured, explicitly or
libraries assume that extended precision (80 bit) floating-point operations
are enabled by default; routines in such libraries could suffer significant
loss of accuracy, typically through so-called "catastrophic cancellation",
-when this option is used to set the precision to less than extended precision.
+when this option is used to set the precision to less than extended precision.
@item -mstackrealign
@opindex mstackrealign
@itemx -mno-pclmul
@itemx -msse4a
@itemx -mno-sse4a
-@itemx -msse5
-@itemx -mno-sse5
+@itemx -mfma4
+@itemx -mno-fma4
@itemx -m3dnow
@itemx -mno-3dnow
@itemx -mpopcnt
@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, SSE5, ABM or
+SSE, SSE2, SSE3, SSSE3, SSE4.1, AVX, AES, PCLMUL, SSE4A, FMA4, ABM or
3DNow!@: extended instruction sets.
These extensions are also available as built-in functions: see
@ref{X86 Built-in Functions}, for details of the functions enabled and
In 64-bit mode, SAHF instruction is used to optimize @code{fmod}, @code{drem}
or @code{remainder} built-in functions: see @ref{Other Builtins} for details.
+@item -mmovbe
+@opindex mmovbe
+This option will enable GCC to use movbe instruction to implement
+@code{__builtin_bswap32} and @code{__builtin_bswap64}.
+
+@item -mcrc32
+@opindex mcrc32
+This option will enable built-in functions, @code{__builtin_ia32_crc32qi},
+@code{__builtin_ia32_crc32hi}. @code{__builtin_ia32_crc32si} and
+@code{__builtin_ia32_crc32di} to generate the crc32 machine instruction.
+
@item -mrecip
@opindex mrecip
This option will enable GCC to use RCPSS and RSQRTSS instructions (and their
For systems that use GNU libc, the default is on.
-@item -mfused-madd
-@itemx -mno-fused-madd
-@opindex mfused-madd
-Enable automatic generation of fused floating point multiply-add instructions
-if the ISA supports such instructions. The -mfused-madd option is on by
-default. The fused multiply-add instructions have a different
-rounding behavior compared to executing a multiply followed by an add.
-
@item -msse2avx
@itemx -mno-sse2avx
@opindex msse2avx
@option{-mdynamic-no-pic} options.
@item -mno-red-zone
-@opindex no-red-zone
+@opindex mno-red-zone
Do not use a so called red zone for x86-64 code. The red zone is mandated
by the x86-64 ABI, it is a 128-byte area beyond the location of the
stack pointer that will not be modified by signal or interrupt handlers
Generate code for inline divides of floating point values
using the maximum throughput algorithm.
+@item -mno-inline-float-divide
+@opindex mno-inline-float-divide
+Do not generate inline code for divides of floating point values.
+
@item -minline-int-divide-min-latency
@opindex minline-int-divide-min-latency
Generate code for inline divides of integer values
Generate code for inline divides of integer values
using the maximum throughput algorithm.
+@item -mno-inline-int-divide
+@opindex mno-inline-int-divide
+Do not generate inline code for divides of integer values.
+
@item -minline-sqrt-min-latency
@opindex minline-sqrt-min-latency
Generate code for inline square roots
Generate code for inline square roots
using the maximum throughput algorithm.
+@item -mno-inline-sqrt
+@opindex mno-inline-sqrt
+Do not generate inline code for sqrt.
+
+@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 -mno-dwarf2-asm
@itemx -mdwarf2-asm
@opindex mno-dwarf2-asm
Tune the instruction scheduling for a particular CPU, Valid values are
itanium, itanium1, merced, itanium2, and mckinley.
-@item -mt
-@itemx -pthread
-@opindex mt
-@opindex pthread
-Add support for multithreading using the POSIX threads library. This
-option sets flags for both the preprocessor and linker. It does
-not affect the thread safety of object code produced by the compiler or
-that of libraries supplied with it. These are HP-UX specific flags.
-
@item -milp32
@itemx -mlp64
@opindex milp32
This is effective only with @option{-msched-control-spec} enabled.
The default is 'enable'.
-@item -msched-ldc
-@itemx -mno-sched-ldc
-@opindex msched-ldc
-@opindex mno-sched-ldc
-(En/Dis)able use of simple data speculation checks ld.c .
-If disabled, only chk.a instructions will be emitted to check
-data speculative loads.
-The default is 'enable'.
-
-@item -mno-sched-control-ldc
-@itemx -msched-control-ldc
-@opindex mno-sched-control-ldc
-@opindex msched-control-ldc
-(Dis/En)able use of ld.c instructions to check control speculative loads.
-If enabled, in case of control speculative load with no speculatively
-scheduled dependent instructions this load will be emitted as ld.sa and
-ld.c will be used to check it.
-The default is 'disable'.
-
-@item -mno-sched-spec-verbose
-@itemx -msched-spec-verbose
-@opindex mno-sched-spec-verbose
-@opindex msched-spec-verbose
-(Dis/En)able printing of the information about speculative motions.
-
@item -mno-sched-prefer-non-data-spec-insns
@itemx -msched-prefer-non-data-spec-insns
@opindex mno-sched-prefer-non-data-spec-insns
speculation a bit more conservative.
The default is 'disable'.
+@item -msched-spec-ldc
+@opindex msched-spec-ldc
+Use a simple data speculation check. This option is on by default.
+
+@item -msched-control-spec-ldc
+@opindex msched-spec-ldc
+Use a simple check for control speculation. This option is on by default.
+
+@item -msched-stop-bits-after-every-cycle
+@opindex msched-stop-bits-after-every-cycle
+Place a stop bit after every cycle when scheduling. This option is on
+by default.
+
+@item -msched-fp-mem-deps-zero-cost
+@opindex msched-fp-mem-deps-zero-cost
+Assume that floating-point stores and loads are not likely to cause a conflict
+when placed into the same instruction group. This option is disabled by
+default.
+
+@item -msel-sched-dont-check-control-spec
+@opindex msel-sched-dont-check-control-spec
+Generate checks for control speculation in selective scheduling.
+This flag is disabled by default.
+
+@item -msched-max-memory-insns=@var{max-insns}
+@opindex msched-max-memory-insns
+Limit on the number of memory insns per instruction group, giving lower
+priority to subsequent memory insns attempting to schedule in the same
+instruction group. Frequently useful to prevent cache bank conflicts.
+The default value is 1.
+
+@item -msched-max-memory-insns-hard-limit
+@opindex msched-max-memory-insns-hard-limit
+Disallow more than `msched-max-memory-insns' in instruction group.
+Otherwise, limit is `soft' meaning that we would prefer non-memory operations
+when limit is reached but may still schedule memory operations.
+
+@end table
+
+@node IA-64/VMS Options
+@subsection IA-64/VMS Options
+
+These @samp{-m} options are defined for the IA-64/VMS implementations:
+
+@table @gcctabopt
+@item -mvms-return-codes
+@opindex mvms-return-codes
+Return VMS condition codes from main. The default is to return POSIX
+style condition (e.g.@ error) codes.
+
+@item -mdebug-main=@var{prefix}
+@opindex mdebug-main=@var{prefix}
+Flag the first routine whose name starts with @var{prefix} as the main
+routine for the debugger.
+
+@item -mmalloc64
+@opindex mmalloc64
+Default to 64bit memory allocation routines.
@end table
@node M32C Options
@multitable @columnfractions 0.20 0.80
@item @strong{Family} @tab @strong{@samp{-mcpu} arguments}
-@item @samp{51qe} @tab @samp{51qe}
+@item @samp{51} @tab @samp{51} @samp{51ac} @samp{51cn} @samp{51em} @samp{51qe}
@item @samp{5206} @tab @samp{5202} @samp{5204} @samp{5206}
@item @samp{5206e} @tab @samp{5206e}
@item @samp{5208} @tab @samp{5207} @samp{5208}
@item @samp{5216} @tab @samp{5214} @samp{5216}
@item @samp{52235} @tab @samp{52230} @samp{52231} @samp{52232} @samp{52233} @samp{52234} @samp{52235}
@item @samp{5225} @tab @samp{5224} @samp{5225}
+@item @samp{52259} @tab @samp{52252} @samp{52254} @samp{52255} @samp{52256} @samp{52258} @samp{52259}
@item @samp{5235} @tab @samp{5232} @samp{5233} @samp{5234} @samp{5235} @samp{523x}
@item @samp{5249} @tab @samp{5249}
@item @samp{5250} @tab @samp{5250}
@item @samp{5272} @tab @samp{5272}
@item @samp{5275} @tab @samp{5274} @samp{5275}
@item @samp{5282} @tab @samp{5280} @samp{5281} @samp{5282} @samp{528x}
+@item @samp{53017} @tab @samp{53011} @samp{53012} @samp{53013} @samp{53014} @samp{53015} @samp{53016} @samp{53017}
@item @samp{5307} @tab @samp{5307}
@item @samp{5329} @tab @samp{5327} @samp{5328} @samp{5329} @samp{532x}
@item @samp{5373} @tab @samp{5372} @samp{5373} @samp{537x}
addressing modes.
@item -minmax
-@itemx -nominmax
+@itemx -mnominmax
@opindex minmax
@opindex mnominmax
Enable the use of 68HC12 min and max instructions.
Generate code for the 210 processor.
@item -mno-lsim
-@opindex no-lsim
+@opindex mno-lsim
Assume that run-time support has been provided and so omit the
simulator library (@file{libsim.a)} from the linker command line.
@end table
+@node MeP Options
+@subsection MeP Options
+@cindex MeP options
+
+@table @gcctabopt
+
+@item -mabsdiff
+@opindex mabsdiff
+Enables the @code{abs} instruction, which is the absolute difference
+between two registers.
+
+@item -mall-opts
+@opindex mall-opts
+Enables all the optional instructions - average, multiply, divide, bit
+operations, leading zero, absolute difference, min/max, clip, and
+saturation.
+
+
+@item -maverage
+@opindex maverage
+Enables the @code{ave} instruction, which computes the average of two
+registers.
+
+@item -mbased=@var{n}
+@opindex mbased=
+Variables of size @var{n} bytes or smaller will be placed in the
+@code{.based} section by default. Based variables use the @code{$tp}
+register as a base register, and there is a 128 byte limit to the
+@code{.based} section.
+
+@item -mbitops
+@opindex mbitops
+Enables the bit operation instructions - bit test (@code{btstm}), set
+(@code{bsetm}), clear (@code{bclrm}), invert (@code{bnotm}), and
+test-and-set (@code{tas}).
+
+@item -mc=@var{name}
+@opindex mc=
+Selects which section constant data will be placed in. @var{name} may
+be @code{tiny}, @code{near}, or @code{far}.
+
+@item -mclip
+@opindex mclip
+Enables the @code{clip} instruction. Note that @code{-mclip} is not
+useful unless you also provide @code{-mminmax}.
+
+@item -mconfig=@var{name}
+@opindex mconfig=
+Selects one of the build-in core configurations. Each MeP chip has
+one or more modules in it; each module has a core CPU and a variety of
+coprocessors, optional instructions, and peripherals. The
+@code{MeP-Integrator} tool, not part of GCC, provides these
+configurations through this option; using this option is the same as
+using all the corresponding command line options. The default
+configuration is @code{default}.
+
+@item -mcop
+@opindex mcop
+Enables the coprocessor instructions. By default, this is a 32-bit
+coprocessor. Note that the coprocessor is normally enabled via the
+@code{-mconfig=} option.
+
+@item -mcop32
+@opindex mcop32
+Enables the 32-bit coprocessor's instructions.
+
+@item -mcop64
+@opindex mcop64
+Enables the 64-bit coprocessor's instructions.
+
+@item -mivc2
+@opindex mivc2
+Enables IVC2 scheduling. IVC2 is a 64-bit VLIW coprocessor.
+
+@item -mdc
+@opindex mdc
+Causes constant variables to be placed in the @code{.near} section.
+
+@item -mdiv
+@opindex mdiv
+Enables the @code{div} and @code{divu} instructions.
+
+@item -meb
+@opindex meb
+Generate big-endian code.
+
+@item -mel
+@opindex mel
+Generate little-endian code.
+
+@item -mio-volatile
+@opindex mio-volatile
+Tells the compiler that any variable marked with the @code{io}
+attribute is to be considered volatile.
+
+@item -ml
+@opindex ml
+Causes variables to be assigned to the @code{.far} section by default.
+
+@item -mleadz
+@opindex mleadz
+Enables the @code{leadz} (leading zero) instruction.
+
+@item -mm
+@opindex mm
+Causes variables to be assigned to the @code{.near} section by default.
+
+@item -mminmax
+@opindex mminmax
+Enables the @code{min} and @code{max} instructions.
+
+@item -mmult
+@opindex mmult
+Enables the multiplication and multiply-accumulate instructions.
+
+@item -mno-opts
+@opindex mno-opts
+Disables all the optional instructions enabled by @code{-mall-opts}.
+
+@item -mrepeat
+@opindex mrepeat
+Enables the @code{repeat} and @code{erepeat} instructions, used for
+low-overhead looping.
+
+@item -ms
+@opindex ms
+Causes all variables to default to the @code{.tiny} section. Note
+that there is a 65536 byte limit to this section. Accesses to these
+variables use the @code{%gp} base register.
+
+@item -msatur
+@opindex msatur
+Enables the saturation instructions. Note that the compiler does not
+currently generate these itself, but this option is included for
+compatibility with other tools, like @code{as}.
+
+@item -msdram
+@opindex msdram
+Link the SDRAM-based runtime instead of the default ROM-based runtime.
+
+@item -msim
+@opindex msim
+Link the simulator runtime libraries.
+
+@item -msimnovec
+@opindex msimnovec
+Link the simulator runtime libraries, excluding built-in support
+for reset and exception vectors and tables.
+
+@item -mtf
+@opindex mtf
+Causes all functions to default to the @code{.far} section. Without
+this option, functions default to the @code{.near} section.
+
+@item -mtiny=@var{n}
+@opindex mtiny=
+Variables that are @var{n} bytes or smaller will be allocated to the
+@code{.tiny} section. These variables use the @code{$gp} base
+register. The default for this option is 4, but note that there's a
+65536 byte limit to the @code{.tiny} section.
+
+@end table
+
@node MIPS Options
@subsection MIPS Options
@cindex MIPS options
@samp{24kec}, @samp{24kef2_1}, @samp{24kef1_1},
@samp{34kc}, @samp{34kf2_1}, @samp{34kf1_1},
@samp{74kc}, @samp{74kf2_1}, @samp{74kf1_1}, @samp{74kf3_2},
+@samp{1004kc}, @samp{1004kf2_1}, @samp{1004kf1_1},
@samp{loongson2e}, @samp{loongson2f},
@samp{m4k},
@samp{octeon},
MIPS32 or MIPS64 architecture, it will make use of the MIPS16e ASE@.
MIPS16 code generation can also be controlled on a per-function basis
-by means of @code{mips16} and @code{nomips16} attributes.
+by means of @code{mips16} and @code{nomips16} attributes.
@xref{Function Attributes}, for more information.
@item -mflip-mips16
This option only has an effect when optimizing for the VR4130.
It normally makes code faster, but at the expense of making it bigger.
It is enabled by default at optimization level @option{-O3}.
+
+@item -msynci
+@itemx -mno-synci
+@opindex msynci
+Enable (disable) generation of @code{synci} instructions on
+architectures that support it. The @code{synci} instructions (if
+enabled) will be generated when @code{__builtin___clear_cache()} is
+compiled.
+
+This option defaults to @code{-mno-synci}, but the default can be
+overridden by configuring with @code{--with-synci}.
+
+When compiling code for single processor systems, it is generally safe
+to use @code{synci}. However, on many multi-core (SMP) systems, it
+will not invalidate the instruction caches on all cores and may lead
+to undefined behavior.
+
+@item -mrelax-pic-calls
+@itemx -mno-relax-pic-calls
+@opindex mrelax-pic-calls
+Try to turn PIC calls that are normally dispatched via register
+@code{$25} into direct calls. This is only possible if the linker can
+resolve the destination at link-time and if the destination is within
+range for a direct call.
+
+@option{-mrelax-pic-calls} is the default if GCC was configured to use
+an assembler and a linker that supports the @code{.reloc} assembly
+directive and @code{-mexplicit-relocs} is in effect. With
+@code{-mno-explicit-relocs}, this optimization can be performed by the
+assembler and the linker alone without help from the compiler.
@end table
@node MMIX Options
@item -mabi=mmixware
@itemx -mabi=gnu
-@opindex mabi-mmixware
+@opindex mabi=mmixware
@opindex mabi=gnu
Generate code that passes function parameters and return values that (in
the called function) are seen as registers @code{$0} and up, as opposed to
Generate code for a PDP-11/10.
@item -mbcopy-builtin
-@opindex bcopy-builtin
+@opindex mbcopy-builtin
Use inline @code{movmemhi} patterns for copying memory. This is the
default.
@itemx -mno-mfcrf
@itemx -mpopcntb
@itemx -mno-popcntb
+@itemx -mpopcntd
+@itemx -mno-popcntd
@itemx -mfprnd
@itemx -mno-fprnd
@itemx -mcmpb
@opindex mno-mfcrf
@opindex mpopcntb
@opindex mno-popcntb
+@opindex mpopcntd
+@opindex mno-popcntd
@opindex mfprnd
@opindex mno-fprnd
@opindex mcmpb
double precision FP reciprocal estimate instruction implemented on the
POWER5 processor and other processors that support the PowerPC V2.02
architecture.
+The @option{-mpopcntd} option allows GCC to generate the popcount
+instruction implemented on the POWER7 processor and other processors
+that support the PowerPC V2.06 architecture.
The @option{-mfprnd} option allows GCC to generate the FP round to
integer instructions implemented on the POWER5+ processor and other
processors that support the PowerPC V2.03 architecture.
instruction scheduling parameters for machine type @var{cpu_type}.
Supported values for @var{cpu_type} are @samp{401}, @samp{403},
@samp{405}, @samp{405fp}, @samp{440}, @samp{440fp}, @samp{464}, @samp{464fp},
-@samp{505}, @samp{601}, @samp{602}, @samp{603}, @samp{603e}, @samp{604},
-@samp{604e}, @samp{620}, @samp{630}, @samp{740}, @samp{7400},
-@samp{7450}, @samp{750}, @samp{801}, @samp{821}, @samp{823},
-@samp{860}, @samp{970}, @samp{8540}, @samp{e300c2}, @samp{e300c3},
-@samp{e500mc}, @samp{ec603e}, @samp{G3}, @samp{G4}, @samp{G5},
+@samp{476}, @samp{476fp}, @samp{505}, @samp{601}, @samp{602}, @samp{603},
+@samp{603e}, @samp{604}, @samp{604e}, @samp{620}, @samp{630}, @samp{740},
+@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{ec603e}, @samp{G3}, @samp{G4}, @samp{G5},
@samp{power}, @samp{power2}, @samp{power3}, @samp{power4},
-@samp{power5}, @samp{power5+}, @samp{power6}, @samp{power6x}, @samp{power7}
+@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}.
following options:
@gccoptlist{-maltivec -mfprnd -mhard-float -mmfcrf -mmultiple @gol
--mnew-mnemonics -mpopcntb -mpower -mpower2 -mpowerpc64 @gol
+-mnew-mnemonics -mpopcntb -mpopcntd -mpower -mpower2 -mpowerpc64 @gol
-mpowerpc-gpopt -mpowerpc-gfxopt -msingle-float -mdouble-float @gol
--msimple-fpu -mstring -mmulhw -mdlmzb -mmfpgpr}
+-msimple-fpu -mstring -mmulhw -mdlmzb -mmfpgpr -mvsx}
The particular options set for any particular CPU will vary between
compiler versions, depending on what setting seems to produce optimal
This option has been deprecated. Use @option{-mspe} and
@option{-mno-spe} instead.
+@item -mvsx
+@itemx -mno-vsx
+@opindex mvsx
+@opindex mno-vsx
+Generate code that uses (does not use) vector/scalar (VSX)
+instructions, and also enable the use of built-in functions that allow
+more direct access to the VSX instruction set.
+
@item -mfloat-gprs=@var{yes/single/double/no}
@itemx -mfloat-gprs
@opindex mfloat-gprs
@itemx -mdouble-float
@opindex msingle-float
@opindex mdouble-float
-Generate code for single or double-precision floating point operations.
-@option{-mdouble-float} implies @option{-msingle-float}.
+Generate code for single or double-precision floating point operations.
+@option{-mdouble-float} implies @option{-msingle-float}.
@item -msimple-fpu
@opindex msimple-fpu
@item -mfpu
@opindex mfpu
-Specify type of floating point unit. Valid values are @var{sp_lite}
+Specify type of floating point unit. Valid values are @var{sp_lite}
(equivalent to -msingle-float -msimple-fpu), @var{dp_lite} (equivalent
to -mdouble-float -msimple-fpu), @var{sp_full} (equivalent to -msingle-float),
and @var{dp_full} (equivalent to -mdouble-float).
@opindex mmulhw
@opindex mno-mulhw
Generate code that uses (does not use) the half-word multiply and
-multiply-accumulate instructions on the IBM 405, 440 and 464 processors.
+multiply-accumulate instructions on the IBM 405, 440, 464 and 476 processors.
These instructions are generated by default when targetting those
processors.
@opindex mdlmzb
@opindex mno-dlmzb
Generate code that uses (does not use) the string-search @samp{dlmzb}
-instruction on the IBM 405, 440 and 464 processors. This instruction is
+instruction on the IBM 405, 440, 464 and 476 processors. This instruction is
generated by default when targetting those processors.
@item -mno-bit-align
default unless you configured GCC using @samp{powerpc-*-eabiaix}.
@item -mcall-sysv-eabi
+@itemx -mcall-eabi
@opindex mcall-sysv-eabi
+@opindex mcall-eabi
Specify both @option{-mcall-sysv} and @option{-meabi} options.
@item -mcall-sysv-noeabi
@opindex mcall-sysv-noeabi
Specify both @option{-mcall-sysv} and @option{-mno-eabi} options.
-@item -mcall-solaris
-@opindex mcall-solaris
-On System V.4 and embedded PowerPC systems compile code for the Solaris
+@item -mcall-aixdesc
+@opindex m
+On System V.4 and embedded PowerPC systems compile code for the AIX
operating system.
@item -mcall-linux
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
+FreeBSD operating system.
+
@item -mcall-netbsd
@opindex mcall-netbsd
On System V.4 and embedded PowerPC systems compile code for the
NetBSD operating system.
+@item -mcall-openbsd
+@opindex mcall-netbsd
+On System V.4 and embedded PowerPC systems compile code for the
+OpenBSD operating system.
+
@item -maix-struct-return
@opindex maix-struct-return
Return all structures in memory (as specified by the AIX ABI)@.
@end table
+@node RX Options
+@subsection RX Options
+@cindex RX Options
+
+These @option{-m} options are defined for RX implementations:
+
+@table @gcctabopt
+@item -m64bit-doubles
+@itemx -m32bit-doubles
+@opindex m64bit-doubles
+@opindex m32bit-doubles
+Make the @code{double} data type be 64-bits (@option{-m64bit-doubles})
+or 32-bits (@option{-m32bit-doubles}) in size. The default is
+@option{-m32bit-doubles}. @emph{Note} the RX's hardware floating
+point instructions are only used for 32-bit floating point values, and
+then only if @option{-ffast-math} has been specified on the command
+line. This is because the RX FPU instructions do not properly support
+denormal (or sub-normal) values.
+
+@item -mbig-endian-data
+@itemx -mlittle-endian-data
+@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
+format.
+
+@item -msmall-data-limit=@var{N}
+@opindex msmall-data-limit
+Specifies the maximum size in bytes of global and static variables
+which can be placed into the small data area. Using the small data
+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.
+
+Note, common variables (variables which have not been initialised) and
+constants are not placed into the small data area as they are assigned
+to other sections in the output executeable.
+
+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 deterimental 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.
+
+@item -msim
+@item -mno-sim
+@opindex msim
+@opindex mno-sim
+Use the simulator runtime. The default is to use the libgloss board
+specific runtime.
+
+@item -mas100-syntax
+@item -mno-as100-syntax
+@opindex mas100-syntax
+@opindex mno-as100-syntax
+When generating assembler output use a syntax that is compatible with
+Renesas's AS100 assembler. This syntax can also be handled by the GAS
+assembler but it has some restrictions so generating it is not the
+default option.
+
+@item -mmax-constant-size=@var{N}
+@opindex mmax-constant-size
+Specifies the maxium size, in bytes, of a constant that can be used as
+an operand in a RX instruction. Although the RX instruction set does
+allow consants of up to 4 bytes in length to be used in instructions,
+a longer value equates to a longer instruction. Thus in some
+circumstances it can be beneficial to restrict the size of constants
+that are used in instructions. Constants that are too big are instead
+placed into a constant pool and referenced via register indirection.
+
+The value @var{N} can be between 0 and 3. A value of 0, the default,
+means that constants of any size are allowed.
+
+@item -mrelax
+@opindex mrelax
+Enable linker relaxation. Linker relaxation is a process whereby the
+linker will attempt to reduce the size of a program by finding shorter
+versions of various instructions. Disabled by default.
+
+@item -mint-register=@var{N}
+@opindex mint-register
+Specify the number of registers to reserve for fast interrupt handler
+functions. The value @var{N} can be between 0 and 4. A value of 1
+means that register @code{r13} will be reserved for ther exclusive use
+of fast interrupt handlers. A value of 2 reserves @code{r13} and
+@code{r12}. A value of 3 reserves @code{r13}, @code{r12} and
+@code{r11}, and a value of 4 reserves @code{r13} through @code{r10}.
+A value of 0, the default, does not reserve any registers.
+@end table
+
+@emph{Note:} The generic GCC command line @option{-ffixed-@var{reg}}
+has special significance to the RX port when used with the
+@code{interrupt} function attribute. This attribute indicates a
+function intended to process fast interrupts. GCC will will ensure
+that it only uses the registers @code{r10}, @code{r11}, @code{r12}
+and/or @code{r13} and only provided that the normal use of the
+corresponding registers have been restricted via the
+@option{-ffixed-@var{reg}} or @option{-mint-register} command line
+options.
+
@node S/390 and zSeries Options
@subsection S/390 and zSeries Options
@cindex S/390 and zSeries Options
@item -mel
@opindex mel
-Compile code for little endian mode.
+Compile code for little endian mode.
@item -mnhwloop
@opindex mnhwloop
@item -mmac
@opindex mmac
-Enable the use of multiply-accumulate instructions. Disabled by default.
+Enable the use of multiply-accumulate instructions. Disabled by default.
@item -mscore5
@opindex mscore5
@item -m2e
Generate code for the SH2e.
+@item -m2a-nofpu
+@opindex m2a-nofpu
+Generate code for the SH2a without FPU, or for a SH2a-FPU in such a way
+that the floating-point unit is not used.
+
+@item -m2a-single-only
+@opindex m2a-single-only
+Generate code for the SH2a-FPU, in such a way that no double-precision
+floating point operations are used.
+
+@item -m2a-single
+@opindex m2a-single
+Generate code for the SH2a-FPU assuming the floating-point unit is in
+single-precision mode by default.
+
+@item -m2a
+@opindex m2a
+Generate code for the SH2a-FPU assuming the floating-point unit is in
+double-precision mode by default.
+
@item -m3
@opindex m3
Generate code for the SH3.
@item -mfmovd
@opindex mfmovd
-Enable the use of the instruction @code{fmovd}.
+Enable the use of the instruction @code{fmovd}. Check @option{-mdalign} for
+alignment constraints.
@item -mhitachi
@opindex mhitachi
@opindex mhint-max-distance
The encoding of the branch hint instruction limits the hint to be within
256 instructions of the branch it is effecting. By default, GCC makes
-sure it is within 125.
+sure it is within 125.
@item -msafe-hints
@opindex msafe-hints
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 behaviour for Cygwin and MinGW targets.
+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 behaviour.
+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
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 choosen.
+
@item -mwin32
@opindex mwin32
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 -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.
In C code, controls the placement of uninitialized global variables.
Unix C compilers have traditionally permitted multiple definitions of
such variables in different compilation units by placing the variables
-in a common block.
-This is the behavior specified by @option{-fcommon}, and is the default
-for GCC on most targets.
+in a common block.
+This is the behavior specified by @option{-fcommon}, and is the default
+for GCC on most targets.
On the other hand, this behavior is not required by ISO C, and on some
targets may carry a speed or code size penalty on variable references.
-The @option{-fno-common} option specifies that the compiler should place
+The @option{-fno-common} option specifies that the compiler should place
uninitialized global variables in the data section of the object file,
rather than generating them as common blocks.
-This has the effect that if the same variable is declared
+This has the effect that if the same variable is declared
(without @code{extern}) in two different compilations,
you will get a multiple-definition error when you link them.
-In this case, you must compile with @option{-fcommon} instead.
-Compiling with @option{-fno-common} is useful on targets for which
+In this case, you must compile with @option{-fcommon} instead.
+Compiling with @option{-fno-common} is useful on targets for which
it provides better performance, or if you wish to verify that the
program will work on other systems which always treat uninitialized
variable declarations this way.
name, such as @code{vector<int> blah(const vector<int> &)}, not the
internal mangled name (e.g., @code{_Z4blahRSt6vectorIiSaIiEE}). The
match is done on substrings: if the @var{sym} parameter is a substring
-of the function name, it is considered to be a match.
+of the function name, it is considered to be a match. For C99 and C++
+extended identifiers, the function name must be given in UTF-8, not
+using universal character names.
@item -fstack-check
@opindex fstack-check
OSDN Git Service
