@option{-ffoo} is @option{-fno-foo}. This manual documents
only one of these two forms, whichever one is not the default.
+Some options take one or more arguments typically separated either
+by a space or by the equals sign (@samp{=}) from the option name.
+Unless documented otherwise, an argument can be either numeric or
+a string. Numeric arguments must typically be small unsigned decimal
+or hexadecimal integers. Hexadecimal arguments must begin with
+the @samp{0x} prefix. Arguments to options that specify a size
+threshold of some sort may be arbitrarily large decimal or hexadecimal
+integers followed by a byte size suffix designating a multiple of bytes
+such as @code{kB} and @code{KiB} for kilobyte and kibibyte, respectively,
+@code{MB} and @code{MiB} for megabyte and mebibyte, @code{GB} and
+@code{GiB} for gigabyte and gigibyte, and so on. Such arguments are
+designated by @var{byte-size} in the following text. Refer to the NIST,
+IEC, and other relevant national and international standards for the full
+listing and explanation of the binary and decimal byte size prefixes.
+
@c man end
@xref{Option Index}, for an index to GCC's options.
@gccoptlist{-fabi-version=@var{n} -fno-access-control @gol
-faligned-new=@var{n} -fargs-in-order=@var{n} -fcheck-new @gol
-fconstexpr-depth=@var{n} -fconstexpr-loop-limit=@var{n} @gol
--ffriend-injection @gol
-fno-elide-constructors @gol
-fno-enforce-eh-specs @gol
--ffor-scope -fno-for-scope -fno-gnu-keywords @gol
+-fno-gnu-keywords @gol
-fno-implicit-templates @gol
-fno-implicit-inline-templates @gol
-fno-implement-inlines -fms-extensions @gol
-fvisibility-ms-compat @gol
-fext-numeric-literals @gol
-Wabi=@var{n} -Wabi-tag -Wconversion-null -Wctor-dtor-privacy @gol
--Wdelete-non-virtual-dtor -Wliteral-suffix -Wmultiple-inheritance @gol
+-Wdelete-non-virtual-dtor -Wdeprecated-copy -Wliteral-suffix @gol
+-Wmultiple-inheritance @gol
-Wnamespaces -Wnarrowing @gol
-Wnoexcept -Wnoexcept-type -Wclass-memaccess @gol
-Wnon-virtual-dtor -Wreorder -Wregister @gol
@gccoptlist{-fsyntax-only -fmax-errors=@var{n} -Wpedantic @gol
-pedantic-errors @gol
-w -Wextra -Wall -Waddress -Waggregate-return @gol
--Walloc-zero -Walloc-size-larger-than=@var{n}
--Walloca -Walloca-larger-than=@var{n} @gol
+-Walloc-zero -Walloc-size-larger-than=@var{byte-size}
+-Walloca -Walloca-larger-than=@var{byte-size} @gol
-Wno-aggressive-loop-optimizations -Warray-bounds -Warray-bounds=@var{n} @gol
-Wno-attributes -Wbool-compare -Wbool-operation @gol
-Wno-builtin-declaration-mismatch @gol
-Wno-builtin-macro-redefined -Wc90-c99-compat -Wc99-c11-compat @gol
--Wc++-compat -Wc++11-compat -Wc++14-compat @gol
+-Wc++-compat -Wc++11-compat -Wc++14-compat -Wc++17-compat @gol
-Wcast-align -Wcast-align=strict -Wcast-function-type -Wcast-qual @gol
--Wchar-subscripts -Wchkp -Wcatch-value -Wcatch-value=@var{n} @gol
+-Wchar-subscripts -Wcatch-value -Wcatch-value=@var{n} @gol
-Wclobbered -Wcomment -Wconditionally-supported @gol
-Wconversion -Wcoverage-mismatch -Wno-cpp -Wdangling-else -Wdate-time @gol
-Wdelete-incomplete @gol
-Wformat-nonliteral -Wformat-overflow=@var{n} @gol
-Wformat-security -Wformat-signedness -Wformat-truncation=@var{n} @gol
-Wformat-y2k -Wframe-address @gol
--Wframe-larger-than=@var{len} -Wno-free-nonheap-object -Wjump-misses-init @gol
+-Wframe-larger-than=@var{byte-size} -Wno-free-nonheap-object @gol
+-Wjump-misses-init @gol
-Wif-not-aligned @gol
-Wignored-qualifiers -Wignored-attributes -Wincompatible-pointer-types @gol
-Wimplicit -Wimplicit-fallthrough -Wimplicit-fallthrough=@var{n} @gol
-Wimplicit-function-declaration -Wimplicit-int @gol
-Winit-self -Winline -Wno-int-conversion -Wint-in-bool-context @gol
-Wno-int-to-pointer-cast -Winvalid-memory-model -Wno-invalid-offsetof @gol
--Winvalid-pch -Wlarger-than=@var{len} @gol
+-Winvalid-pch -Wlarger-than=@var{byte-size} @gol
-Wlogical-op -Wlogical-not-parentheses -Wlong-long @gol
-Wmain -Wmaybe-uninitialized -Wmemset-elt-size -Wmemset-transposed-args @gol
--Wmisleading-indentation -Wmissing-braces @gol
+-Wmisleading-indentation -Wmissing-attributes -Wmissing-braces @gol
-Wmissing-field-initializers -Wmissing-include-dirs @gol
-Wno-multichar -Wmultistatement-macros -Wnonnull -Wnonnull-compare @gol
-Wnormalized=@r{[}none@r{|}id@r{|}nfc@r{|}nfkc@r{]} @gol
-Wsign-compare -Wsign-conversion -Wfloat-conversion @gol
-Wno-scalar-storage-order -Wsizeof-pointer-div @gol
-Wsizeof-pointer-memaccess -Wsizeof-array-argument @gol
--Wstack-protector -Wstack-usage=@var{len} -Wstrict-aliasing @gol
+-Wstack-protector -Wstack-usage=@var{byte-size} -Wstrict-aliasing @gol
-Wstrict-aliasing=n -Wstrict-overflow -Wstrict-overflow=@var{n} @gol
-Wstringop-overflow=@var{n} -Wstringop-truncation @gol
-Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}malloc@r{]} @gol
-Wswitch-unreachable -Wsync-nand @gol
-Wsystem-headers -Wtautological-compare -Wtrampolines -Wtrigraphs @gol
-Wtype-limits -Wundef @gol
--Wuninitialized -Wunknown-pragmas -Wunsafe-loop-optimizations @gol
+-Wuninitialized -Wunknown-pragmas @gol
-Wunsuffixed-float-constants -Wunused -Wunused-function @gol
-Wunused-label -Wunused-local-typedefs -Wunused-macros @gol
-Wunused-parameter -Wno-unused-result @gol
-Wunused-const-variable -Wunused-const-variable=@var{n} @gol
-Wunused-but-set-parameter -Wunused-but-set-variable @gol
-Wuseless-cast -Wvariadic-macros -Wvector-operation-performance @gol
--Wvla -Wvla-larger-than=@var{n} -Wvolatile-register-var -Wwrite-strings @gol
+-Wvla -Wvla-larger-than=@var{byte-size} -Wvolatile-register-var @gol
+-Wwrite-strings @gol
-Wzero-as-null-pointer-constant -Whsa}
@item C and Objective-C-only Warning Options
@gccoptlist{-g -g@var{level} -gdwarf -gdwarf-@var{version} @gol
-ggdb -grecord-gcc-switches -gno-record-gcc-switches @gol
-gstabs -gstabs+ -gstrict-dwarf -gno-strict-dwarf @gol
+-gas-loc-support -gno-as-loc-support @gol
+-gas-locview-support -gno-as-locview-support @gol
-gcolumn-info -gno-column-info @gol
-gstatement-frontiers -gno-statement-frontiers @gol
+-gvariable-location-views -gno-variable-location-views @gol
+-ginternal-reset-location-views -gno-internal-reset-location-views @gol
+-ginline-points -gno-inline-points @gol
-gvms -gxcoff -gxcoff+ -gz@r{[}=@var{type}@r{]} @gol
+-gsplit-dwarf @gol
-fdebug-prefix-map=@var{old}=@var{new} -fdebug-types-section @gol
-fno-eliminate-unused-debug-types @gol
-femit-struct-debug-baseonly -femit-struct-debug-reduced @gol
@item Optimization Options
@xref{Optimize Options,,Options that Control Optimization}.
-@gccoptlist{-faggressive-loop-optimizations -falign-functions[=@var{n}] @gol
--falign-jumps[=@var{n}] @gol
--falign-labels[=@var{n}] -falign-loops[=@var{n}] @gol
+@gccoptlist{-faggressive-loop-optimizations @gol
+-falign-functions[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
+-falign-jumps[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
+-falign-labels[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
+-falign-loops[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
-fassociative-math -fauto-profile -fauto-profile[=@var{path}] @gol
-fauto-inc-dec -fbranch-probabilities @gol
-fbranch-target-load-optimize -fbranch-target-load-optimize2 @gol
-freorder-blocks-algorithm=@var{algorithm} @gol
-freorder-blocks-and-partition -freorder-functions @gol
-frerun-cse-after-loop -freschedule-modulo-scheduled-loops @gol
--frounding-math -fsched2-use-superblocks -fsched-pressure @gol
+-frounding-math -fsave-optimization-record @gol
+-fsched2-use-superblocks -fsched-pressure @gol
-fsched-spec-load -fsched-spec-load-dangerous @gol
-fsched-stalled-insns-dep[=@var{n}] -fsched-stalled-insns[=@var{n}] @gol
-fsched-group-heuristic -fsched-critical-path-heuristic @gol
-fsanitize=@var{style} -fsanitize-recover -fsanitize-recover=@var{style} @gol
-fasan-shadow-offset=@var{number} -fsanitize-sections=@var{s1},@var{s2},... @gol
-fsanitize-undefined-trap-on-error -fbounds-check @gol
--fcheck-pointer-bounds -fchkp-check-incomplete-type @gol
--fchkp-first-field-has-own-bounds -fchkp-narrow-bounds @gol
--fchkp-narrow-to-innermost-array -fchkp-optimize @gol
--fchkp-use-fast-string-functions -fchkp-use-nochk-string-functions @gol
--fchkp-use-static-bounds -fchkp-use-static-const-bounds @gol
--fchkp-treat-zero-dynamic-size-as-infinite -fchkp-check-read @gol
--fchkp-check-read -fchkp-check-write -fchkp-store-bounds @gol
--fchkp-instrument-calls -fchkp-instrument-marked-only @gol
--fchkp-use-wrappers -fchkp-flexible-struct-trailing-arrays@gol
--fcf-protection==@r{[}full@r{|}branch@r{|}return@r{|}none@r{]} @gol
+-fcf-protection=@r{[}full@r{|}branch@r{|}return@r{|}none@r{]} @gol
-fstack-protector -fstack-protector-all -fstack-protector-strong @gol
-fstack-protector-explicit -fstack-check @gol
-fstack-limit-register=@var{reg} -fstack-limit-symbol=@var{sym} @gol
@item Linker Options
@xref{Link Options,,Options for Linking}.
@gccoptlist{@var{object-file-name} -fuse-ld=@var{linker} -l@var{library} @gol
--nostartfiles -nodefaultlibs -nostdlib -pie -pthread -rdynamic @gol
+-nostartfiles -nodefaultlibs -nolibc -nostdlib @gol
+-pie -pthread -rdynamic @gol
-s -static -static-pie -static-libgcc -static-libstdc++ @gol
-static-libasan -static-libtsan -static-liblsan -static-libubsan @gol
--static-libmpx -static-libmpxwrappers @gol
-shared -shared-libgcc -symbolic @gol
-T @var{script} -Wl,@var{option} -Xlinker @var{option} @gol
-u @var{symbol} -z @var{keyword}}
@gccoptlist{-mabi=@var{name} -mbig-endian -mlittle-endian @gol
-mgeneral-regs-only @gol
-mcmodel=tiny -mcmodel=small -mcmodel=large @gol
--mstrict-align @gol
+-mstrict-align -mno-strict-align @gol
-momit-leaf-frame-pointer @gol
-mtls-dialect=desc -mtls-dialect=traditional @gol
-mtls-size=@var{size} @gol
-mpc-relative-literal-loads @gol
-msign-return-address=@var{scope} @gol
-march=@var{name} -mcpu=@var{name} -mtune=@var{name} @gol
--moverride=@var{string} -mverbose-cost-dump}
+-moverride=@var{string} -mverbose-cost-dump -mtrack-speculation}
@emph{Adapteva Epiphany Options}
@gccoptlist{-mhalf-reg-file -mprefer-short-insn-regs @gol
-mmemcpy -mxl-soft-mul -mxl-soft-div -mxl-barrel-shift @gol
-mxl-pattern-compare -mxl-stack-check -mxl-gp-opt -mno-clearbss @gol
-mxl-multiply-high -mxl-float-convert -mxl-float-sqrt @gol
--mbig-endian -mlittle-endian -mxl-reorder -mxl-mode-@var{app-model}}
+-mbig-endian -mlittle-endian -mxl-reorder -mxl-mode-@var{app-model}
+-mpic-data-is-text-relative}
@emph{MIPS Options}
@gccoptlist{-EL -EB -march=@var{arch} -mtune=@var{arch} @gol
-meva -mno-eva @gol
-mvirt -mno-virt @gol
-mxpa -mno-xpa @gol
+-mcrc -mno-crc @gol
+-mginv -mno-ginv @gol
-mmicromips -mno-micromips @gol
-mmsa -mno-msa @gol
-mfpu=@var{fpu-type} @gol
@emph{PDP-11 Options}
@gccoptlist{-mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45 -m10 @gol
--mbcopy -mbcopy-builtin -mint32 -mno-int16 @gol
--mint16 -mno-int32 -mfloat32 -mno-float64 @gol
--mfloat64 -mno-float32 -mabshi -mno-abshi @gol
--mbranch-expensive -mbranch-cheap @gol
--munix-asm -mdec-asm}
+-mint32 -mno-int16 -mint16 -mno-int32 @gol
+-mfloat32 -mno-float64 -mfloat64 -mno-float32 @gol
+-msplit -munix-asm -mdec-asm -mgnu-asm}
@emph{picoChip Options}
@gccoptlist{-mae=@var{ae_type} -mvliw-lookahead=@var{N} @gol
@emph{PowerPC Options}
See RS/6000 and PowerPC Options.
+@emph{PowerPC SPE Options}
+@gccoptlist{-mcpu=@var{cpu-type} @gol
+-mtune=@var{cpu-type} @gol
+-mmfcrf -mno-mfcrf -mpopcntb -mno-popcntb @gol
+-mfull-toc -mminimal-toc -mno-fp-in-toc -mno-sum-in-toc @gol
+-m32 -mxl-compat -mno-xl-compat @gol
+-malign-power -malign-natural @gol
+-msoft-float -mhard-float -mmultiple -mno-multiple @gol
+-msingle-float -mdouble-float @gol
+-mupdate -mno-update @gol
+-mavoid-indexed-addresses -mno-avoid-indexed-addresses @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
+-msingle-pic-base @gol
+-mprioritize-restricted-insns=@var{priority} @gol
+-msched-costly-dep=@var{dependence_type} @gol
+-minsert-sched-nops=@var{scheme} @gol
+-mcall-sysv -mcall-netbsd @gol
+-maix-struct-return -msvr4-struct-return @gol
+-mabi=@var{abi-type} -msecure-plt -mbss-plt @gol
+-mblock-move-inline-limit=@var{num} @gol
+-misel -mno-isel @gol
+-misel=yes -misel=no @gol
+-mspe -mno-spe @gol
+-mspe=yes -mspe=no @gol
+-mfloat-gprs=yes -mfloat-gprs=no -mfloat-gprs=single -mfloat-gprs=double @gol
+-mprototype -mno-prototype @gol
+-msim -mmvme -mads -myellowknife -memb -msdata @gol
+-msdata=@var{opt} -mvxworks -G @var{num} @gol
+-mrecip -mrecip=@var{opt} -mno-recip -mrecip-precision @gol
+-mno-recip-precision @gol
+-mpointers-to-nested-functions -mno-pointers-to-nested-functions @gol
+-msave-toc-indirect -mno-save-toc-indirect @gol
+-mcompat-align-parm -mno-compat-align-parm @gol
+-mfloat128 -mno-float128 @gol
+-mgnu-attribute -mno-gnu-attribute @gol
+-mstack-protector-guard=@var{guard} -mstack-protector-guard-reg=@var{reg} @gol
+-mstack-protector-guard-offset=@var{offset}}
+
@emph{RISC-V Options}
@gccoptlist{-mbranch-cost=@var{N-instruction} @gol
-mplt -mno-plt @gol
-msave-restore -mno-save-restore @gol
-mstrict-align -mno-strict-align @gol
-mcmodel=medlow -mcmodel=medany @gol
--mexplicit-relocs -mno-explicit-relocs @gol}
+-mexplicit-relocs -mno-explicit-relocs @gol
+-mrelax -mno-relax @gol}
@emph{RL78 Options}
@gccoptlist{-msim -mmul=none -mmul=g13 -mmul=g14 -mallregs @gol
-m64 -m32 -mxl-compat -mno-xl-compat -mpe @gol
-malign-power -malign-natural @gol
-msoft-float -mhard-float -mmultiple -mno-multiple @gol
--msingle-float -mdouble-float -msimple-fpu @gol
-mupdate -mno-update @gol
-mavoid-indexed-addresses -mno-avoid-indexed-addresses @gol
-mfused-madd -mno-fused-madd -mbit-align -mno-bit-align @gol
-mprioritize-restricted-insns=@var{priority} @gol
-msched-costly-dep=@var{dependence_type} @gol
-minsert-sched-nops=@var{scheme} @gol
--mcall-sysv -mcall-netbsd @gol
+-mcall-aixdesc -mcall-eabi -mcall-freebsd @gol
+-mcall-linux -mcall-netbsd -mcall-openbsd @gol
+-mcall-sysv -mcall-sysv-eabi -mcall-sysv-noeabi @gol
+-mtraceback=@var{traceback_type} @gol
-maix-struct-return -msvr4-struct-return @gol
-mabi=@var{abi-type} -msecure-plt -mbss-plt @gol
-mblock-move-inline-limit=@var{num} @gol
+-mblock-compare-inline-limit=@var{num} @gol
+-mblock-compare-inline-loop-limit=@var{num} @gol
+-mstring-compare-inline-limit=@var{num} @gol
-misel -mno-isel @gol
-misel=yes -misel=no @gol
--mspe -mno-spe @gol
--mspe=yes -mspe=no @gol
--mpaired @gol
-mvrsave -mno-vrsave @gol
-mmulhw -mno-mulhw @gol
-mdlmzb -mno-dlmzb @gol
--mfloat-gprs=yes -mfloat-gprs=no -mfloat-gprs=single -mfloat-gprs=double @gol
-mprototype -mno-prototype @gol
-msim -mmvme -mads -myellowknife -memb -msdata @gol
--msdata=@var{opt} -mvxworks -G @var{num} @gol
+-msdata=@var{opt} -mreadonly-in-sdata -mvxworks -G @var{num} @gol
-mrecip -mrecip=@var{opt} -mno-recip -mrecip-precision @gol
-mno-recip-precision @gol
-mveclibabi=@var{type} -mfriz -mno-friz @gol
-mpointers-to-nested-functions -mno-pointers-to-nested-functions @gol
-msave-toc-indirect -mno-save-toc-indirect @gol
-mpower8-fusion -mno-mpower8-fusion -mpower8-vector -mno-power8-vector @gol
--mcrypto -mno-crypto -mhtm -mno-htm -mdirect-move -mno-direct-move @gol
+-mcrypto -mno-crypto -mhtm -mno-htm @gol
-mquad-memory -mno-quad-memory @gol
-mquad-memory-atomic -mno-quad-memory-atomic @gol
-mcompat-align-parm -mno-compat-align-parm @gol
-mmmx -msse -msse2 -msse3 -mssse3 -msse4.1 -msse4.2 -msse4 -mavx @gol
-mavx2 -mavx512f -mavx512pf -mavx512er -mavx512cd -mavx512vl @gol
-mavx512bw -mavx512dq -mavx512ifma -mavx512vbmi -msha -maes @gol
--mpclmul -mfsgsbase -mrdrnd -mf16c -mfma @gol
+-mpclmul -mfsgsbase -mrdrnd -mf16c -mfma -mpconfig -mwbnoinvd @gol
-mprefetchwt1 -mclflushopt -mxsavec -mxsaves @gol
-msse4a -m3dnow -m3dnowa -mpopcnt -mabm -mbmi -mtbm -mfma4 -mxop @gol
--mlzcnt -mbmi2 -mfxsr -mxsave -mxsaveopt -mrtm -mlwp -mmpx @gol
--mmwaitx -mclzero -mpku -mthreads -mgfni -mvaes @gol
--mcet -mibt -mshstk -mforce-indirect-call -mavx512vbmi2 @gol
--mvpclmulqdq -mavx512bitalg -mavx512vpopcntdq @gol
+-mlzcnt -mbmi2 -mfxsr -mxsave -mxsaveopt -mrtm -mlwp @gol
+-mmwaitx -mclzero -mpku -mthreads -mgfni -mvaes -mwaitpkg @gol
+-mshstk -mforce-indirect-call -mavx512vbmi2 @gol
+-mvpclmulqdq -mavx512bitalg -mmovdiri -mmovdir64b -mavx512vpopcntdq
+-mcldemote @gol
-mms-bitfields -mno-align-stringops -minline-all-stringops @gol
-minline-stringops-dynamically -mstringop-strategy=@var{alg} @gol
-mmemcpy-strategy=@var{strategy} -mmemset-strategy=@var{strategy} @gol
the mangling now changes starting with the twelfth occurrence. It also
implies @option{-fnew-inheriting-ctors}.
+Version 12, which first appeared in G++ 8, corrects the calling
+conventions for empty classes on the x86_64 target and for classes
+with only deleted copy/move constructors. It accidentally changes the
+calling convention for classes with a deleted copy constructor and a
+trivial move constructor.
+
+Version 13, which first appeared in G++ 8.2, fixes the accidental
+change in version 12.
+
See also @option{-Wabi}.
@item -fabi-compat-version=@var{n}
mangled name when defining a symbol with an incorrect mangled name.
This switch specifies which ABI version to use for the alias.
-With @option{-fabi-version=0} (the default), this defaults to 8 (GCC 5
+With @option{-fabi-version=0} (the default), this defaults to 11 (GCC 7
compatibility). If another ABI version is explicitly selected, this
defaults to 0. For compatibility with GCC versions 3.2 through 4.9,
use @option{-fabi-compat-version=2}.
of the final standard, so it is disabled by default. This option is
deprecated, and may be removed in a future version of G++.
-@item -ffriend-injection
-@opindex ffriend-injection
-Inject friend functions into the enclosing namespace, so that they are
-visible outside the scope of the class in which they are declared.
-Friend functions were documented to work this way in the old Annotated
-C++ Reference Manual.
-However, in ISO C++ a friend function that is not declared
-in an enclosing scope can only be found using argument dependent
-lookup. GCC defaults to the standard behavior.
-
-This option is for compatibility, and may be removed in a future
-release of G++.
-
@item -fno-elide-constructors
@opindex fno-elide-constructors
The C++ standard allows an implementation to omit creating a temporary
@option{-fextern-tls-init}. On targets that do not support symbol
aliases, the default is @option{-fno-extern-tls-init}.
-@item -ffor-scope
-@itemx -fno-for-scope
-@opindex ffor-scope
-@opindex fno-for-scope
-If @option{-ffor-scope} is specified, the scope of variables declared in
-a @i{for-init-statement} is limited to the @code{for} loop itself,
-as specified by the C++ standard.
-If @option{-fno-for-scope} is specified, the scope of variables declared in
-a @i{for-init-statement} extends to the end of the enclosing scope,
-as was the case in old versions of G++, and other (traditional)
-implementations of C++.
-
-This option is deprecated and the associated non-standard
-functionality will be removed.
-
@item -fno-gnu-keywords
@opindex fno-gnu-keywords
Do not recognize @code{typeof} as a keyword, so that code can use this
base class does not have a virtual destructor. This warning is enabled
by @option{-Wall}.
+@item -Wdeprecated-copy @r{(C++ and Objective-C++ only)}
+@opindex Wdeprecated-copy
+@opindex Wno-deprecated-copy
+Warn that the implicit declaration of a copy constructor or copy
+assignment operator is deprecated if the class has a user-provided
+copy constructor, copy assignment operator, or destructor, in C++11
+and up. This warning is enabled by @option{-Wall}.
+
+@item -Wno-init-list-lifetime @r{(C++ and Objective-C++ only)}
+@opindex Winit-list-lifetime
+@opindex Wno-init-list-lifetime
+Do not warn about uses of @code{std::initializer_list} that are likely
+to result in dangling pointers. Since the underlying array for an
+@code{initializer_list} is handled like a normal C++ temporary object,
+it is easy to inadvertently keep a pointer to the array past the end
+of the array's lifetime. For example:
+
+@itemize @bullet
+@item
+If a function returns a temporary @code{initializer_list}, or a local
+@code{initializer_list} variable, the array's lifetime ends at the end
+of the return statement, so the value returned has a dangling pointer.
+
+@item
+If a new-expression creates an @code{initializer_list}, the array only
+lives until the end of the enclosing full-expression, so the
+@code{initializer_list} in the heap has a dangling pointer.
+
+@item
+When an @code{initializer_list} variable is assigned from a
+brace-enclosed initializer list, the temporary array created for the
+right side of the assignment only lives until the end of the
+full-expression, so at the next statement the @code{initializer_list}
+variable has a dangling pointer.
+
+@smallexample
+// li's initial underlying array lives as long as li
+std::initializer_list<int> li = @{ 1,2,3 @};
+// assignment changes li to point to a temporary array
+li = @{ 4, 5 @};
+// now the temporary is gone and li has a dangling pointer
+int i = li.begin()[0] // undefined behavior
+@end smallexample
+
+@item
+When a list constructor stores the @code{begin} pointer from the
+@code{initializer_list} argument, this doesn't extend the lifetime of
+the array, so if a class variable is constructed from a temporary
+@code{initializer_list}, the pointer is left dangling by the end of
+the variable declaration statement.
+
+@end itemize
+
@item -Wliteral-suffix @r{(C++ and Objective-C++ only)}
@opindex Wliteral-suffix
@opindex Wno-literal-suffix
@end smallexample
@noindent
-In C++14, @code{f} calls calls @code{f<void(*)()>}, but in
+In C++14, @code{f} calls @code{f<void(*)()>}, but in
C++17 it calls @code{f<void(*)()noexcept>}.
@item -Wclass-memaccess @r{(C++ and Objective-C++ only)}
@opindex Wclass-memaccess
+@opindex Wno-class-memaccess
Warn when the destination of a call to a raw memory function such as
@code{memset} or @code{memcpy} is an object of class type, and when writing
into such an object might bypass the class non-trivial or deleted constructor
@item -Wtemplates @r{(C++ and Objective-C++ only)}
@opindex Wtemplates
+@opindex Wno-templates
Warn when a primary template declaration is encountered. Some coding
rules disallow templates, and this may be used to enforce that rule.
The warning is inactive inside a system header file, such as the STL, so
@item -Wmultiple-inheritance @r{(C++ and Objective-C++ only)}
@opindex Wmultiple-inheritance
+@opindex Wno-multiple-inheritance
Warn when a class is defined with multiple direct base classes. Some
coding rules disallow multiple inheritance, and this may be used to
enforce that rule. The warning is inactive inside a system header file,
@item -Wvirtual-inheritance
@opindex Wvirtual-inheritance
+@opindex Wno-virtual-inheritance
Warn when a class is defined with a virtual direct base class. Some
coding rules disallow multiple inheritance, and this may be used to
enforce that rule. The warning is inactive inside a system header file,
@item -Wnamespaces
@opindex Wnamespaces
+@opindex Wno-namespaces
Warn when a namespace definition is opened. Some coding rules disallow
namespaces, and this may be used to enforce that rule. The warning is
inactive inside a system header file, such as the STL, so one can still
done; each error message appears on a single line. This is the
default for all front ends.
+Note - this option also affects the display of the @samp{#error} and
+@samp{#warning} pre-processor directives, and the @samp{deprecated}
+function/type/variable attribute. It does not however affect the
+@samp{pragma GCC warning} and @samp{pragma GCC error} pragmas.
+
@item -fdiagnostics-show-location=once
@opindex fdiagnostics-show-location
Only meaningful in line-wrapping mode. Instructs the diagnostic messages
@itemx -pedantic
@opindex pedantic
@opindex Wpedantic
+@opindex Wno-pedantic
Issue all the warnings demanded by strict ISO C and ISO C++;
reject all programs that use forbidden extensions, and some other
programs that do not follow ISO C and ISO C++. For ISO C, follows the
-Wmemset-elt-size @gol
-Wmemset-transposed-args @gol
-Wmisleading-indentation @r{(only for C/C++)} @gol
+-Wmissing-attributes @gol
-Wmissing-braces @r{(only for C/ObjC)} @gol
-Wmultistatement-macros @gol
-Wnarrowing @r{(only for C++)} @gol
@item -Wchkp
@opindex Wchkp
+@opindex Wno-chkp
Warn about an invalid memory access that is found by Pointer Bounds Checker
(@option{-fcheck-pointer-bounds}).
@item -Wno-coverage-mismatch
@opindex Wno-coverage-mismatch
+@opindex Wcoverage-mismatch
Warn if feedback profiles do not match when using the
@option{-fprofile-use} option.
If a source file is changed between compiling with @option{-fprofile-gen} and
@table @gcctabopt
@item -Wformat-overflow
-@item -Wformat-overflow=1
+@itemx -Wformat-overflow=1
@opindex Wformat-overflow
@opindex Wno-format-overflow
Level @var{1} of @option{-Wformat-overflow} enabled by @option{-Wformat}
@smallexample
void f (int a, int b)
@{
- char buf [12];
+ char buf [13];
sprintf (buf, "a = %i, b = %i\n", a, b);
@}
@end smallexample
@table @gcctabopt
@item -Wformat-truncation
-@item -Wformat-truncation=1
+@itemx -Wformat-truncation=1
@opindex Wformat-truncation
-@opindex Wno-format-overflow
+@opindex Wno-format-truncation
Level @var{1} of @option{-Wformat-truncation} enabled by @option{-Wformat}
employs a conservative approach that warns only about calls to bounded
functions whose return value is unused and that will most likely result
@opindex Wif-not-aligned
@opindex Wno-if-not-aligned
Control if warning triggered by the @code{warn_if_not_aligned} attribute
-should be issued. This is is enabled by default.
+should be issued. This is enabled by default.
Use @option{-Wno-if-not-aligned} to disable it.
@item -Wignored-qualifiers @r{(C and C++ only)}
This warning is enabled by @option{-Wall} in C and C++.
+@item -Wmissing-attributes
+@opindex Wmissing-attributes
+@opindex Wno-missing-attributes
+Warn when a declaration of a function is missing one or more attributes
+that a related function is declared with and whose absence may adversely
+affect the correctness or efficiency of generated code. For example, in
+C++, the warning is issued when an explicit specialization of a primary
+template declared with attribute @code{alloc_align}, @code{alloc_size},
+@code{assume_aligned}, @code{format}, @code{format_arg}, @code{malloc},
+or @code{nonnull} is declared without it. Attributes @code{deprecated},
+@code{error}, and @code{warning} suppress the warning.
+(@pxref{Function Attributes}).
+
+@option{-Wmissing-attributes} is enabled by @option{-Wall}.
+
+For example, since the declaration of the primary function template
+below makes use of both attribute @code{malloc} and @code{alloc_size}
+the declaration of the explicit specialization of the template is
+diagnosed because it is missing one of the attributes.
+
+@smallexample
+template <class T>
+T* __attribute__ ((malloc, alloc_size (1)))
+allocate (size_t);
+
+template <>
+void* __attribute__ ((malloc)) // missing alloc_size
+allocate<void> (size_t);
+@end smallexample
+
@item -Wmissing-braces
@opindex Wmissing-braces
@opindex Wno-missing-braces
message, even when @option{-Wno-return-type} is specified. The only
exceptions are @code{main} and functions defined in system headers.
-This warning is enabled by @option{-Wall}.
+This warning is enabled by default for C++ and is enabled by @option{-Wall}.
@item -Wshift-count-negative
@opindex Wshift-count-negative
@item -Wunused-local-typedefs @r{(C, Objective-C, C++ and Objective-C++ only)}
@opindex Wunused-local-typedefs
+@opindex Wno-unused-local-typedefs
Warn when a typedef locally defined in a function is not used.
This warning is enabled by @option{-Wall}.
@table @gcctabopt
@item -Wstringop-overflow
-@item -Wstringop-overflow=1
+@itemx -Wstringop-overflow=1
@opindex Wstringop-overflow
@opindex Wno-stringop-overflow
The @option{-Wstringop-overflow=1} option uses type-zero Object Size Checking
of @code{realloc} has been deprecated) relying on it may result in subtle
portability bugs and should be avoided.
-@item -Walloc-size-larger-than=@var{n}
+@item -Walloc-size-larger-than=@var{byte-size}
+@opindex Walloc-size-larger-than=
+@opindex Wno-alloc-size-larger-than
Warn about calls to functions decorated with attribute @code{alloc_size}
that attempt to allocate objects larger than the specified number of bytes,
or where the result of the size computation in an integer type with infinite
-precision would exceed @code{SIZE_MAX / 2}. The option argument @var{n}
-may end in one of the standard suffixes designating a multiple of bytes
-such as @code{kB} and @code{KiB} for kilobyte and kibibyte, respectively,
-@code{MB} and @code{MiB} for megabyte and mebibyte, and so on.
+precision would exceed the value of @samp{PTRDIFF_MAX} on the target.
+@option{-Walloc-size-larger-than=}@samp{PTRDIFF_MAX} is enabled by default.
+Warnings controlled by the option can be disabled either by specifying
+@var{byte-size} of @samp{SIZE_MAX} or more or by
+@option{-Wno-alloc-size-larger-than}.
@xref{Function Attributes}.
+@item -Wno-alloc-size-larger-than
+@opindex Wno-alloc-size-larger-than
+Disable @option{-Walloc-size-larger-than=} warnings. The option is
+equivalent to @option{-Walloc-size-larger-than=}@samp{SIZE_MAX} or
+larger.
+
@item -Walloca
@opindex Wno-alloca
@opindex Walloca
This option warns on all uses of @code{alloca} in the source.
-@item -Walloca-larger-than=@var{n}
-This option warns on calls to @code{alloca} that are not bounded by a
-controlling predicate limiting its argument of integer type to at most
-@var{n} bytes, or calls to @code{alloca} where the bound is unknown.
-Arguments of non-integer types are considered unbounded even if they
-appear to be constrained to the expected range.
+@item -Walloca-larger-than=@var{byte-size}
+@opindex -Walloca-larger-than=
+@opindex -Wno-alloca-larger-than
+This option warns on calls to @code{alloca} with an integer argument whose
+value is either zero, or that is not bounded by a controlling predicate
+that limits its value to at most @var{byte-size}. It also warns for calls
+to @code{alloca} where the bound value is unknown. Arguments of non-integer
+types are considered unbounded even if they appear to be constrained to
+the expected range.
For example, a bounded case of @code{alloca} could be:
This option also warns when @code{alloca} is used in a loop.
-This warning is not enabled by @option{-Wall}, and is only active when
-@option{-ftree-vrp} is active (default for @option{-O2} and above).
+@option{-Walloca-larger-than=}@samp{PTRDIFF_MAX} is enabled by default
+but is usually only effective when @option{-ftree-vrp} is active (default
+for @option{-O2} and above).
-See also @option{-Wvla-larger-than=@var{n}}.
+See also @option{-Wvla-larger-than=}@samp{byte-size}.
+
+@item -Wno-alloca-larger-than
+@opindex Wno-alloca-larger-than
+Disable @option{-Walloca-larger-than=} warnings. The option is
+equivalent to @option{-Walloca-larger-than=}@samp{SIZE_MAX} or larger.
@item -Warray-bounds
@itemx -Warray-bounds=@var{n}
This warning is enabled by @option{-Wshadow=local}.
-@item -Wlarger-than=@var{len}
-@opindex Wlarger-than=@var{len}
-@opindex Wlarger-than-@var{len}
-Warn whenever an object of larger than @var{len} bytes is defined.
-
-@item -Wframe-larger-than=@var{len}
-@opindex Wframe-larger-than
-Warn if the size of a function frame is larger than @var{len} bytes.
+@item -Wlarger-than=@var{byte-size}
+@opindex Wlarger-than=
+@opindex Wlarger-than-@var{byte-size}
+Warn whenever an object is defined whose size exceeds @var{byte-size}.
+@option{-Wlarger-than=}@samp{PTRDIFF_MAX} is enabled by default.
+Warnings controlled by the option can be disabled either by specifying
+@var{byte-size} of @samp{SIZE_MAX} or more or by
+@option{-Wno-larger-than}.
+
+@item -Wno-larger-than
+@opindex Wno-larger-than
+Disable @option{-Wlarger-than=} warnings. The option is equivalent
+to @option{-Wlarger-than=}@samp{SIZE_MAX} or larger.
+
+@item -Wframe-larger-than=@var{byte-size}
+@opindex Wframe-larger-than=
+@opindex Wno-frame-larger-than
+Warn if the size of a function frame exceeds @var{byte-size}.
The computation done to determine the stack frame size is approximate
and not conservative.
-The actual requirements may be somewhat greater than @var{len}
+The actual requirements may be somewhat greater than @var{byte-size}
even if you do not get a warning. In addition, any space allocated
via @code{alloca}, variable-length arrays, or related constructs
is not included by the compiler when determining
whether or not to issue a warning.
+@option{-Wframe-larger-than=}@samp{PTRDIFF_MAX} is enabled by default.
+Warnings controlled by the option can be disabled either by specifying
+@var{byte-size} of @samp{SIZE_MAX} or more or by
+@option{-Wno-frame-larger-than}.
+
+@item -Wno-frame-larger-than
+@opindex Wno-frame-larger-than
+Disable @option{-Wframe-larger-than=} warnings. The option is equivalent
+to @option{-Wframe-larger-than=}@samp{SIZE_MAX} or larger.
@item -Wno-free-nonheap-object
@opindex Wno-free-nonheap-object
Do not warn when attempting to free an object that was not allocated
on the heap.
-@item -Wstack-usage=@var{len}
+@item -Wstack-usage=@var{byte-size}
@opindex Wstack-usage
-Warn if the stack usage of a function might be larger than @var{len} bytes.
+@opindex Wno-stack-usage
+Warn if the stack usage of a function might exceed @var{byte-size}.
The computation done to determine the stack usage is conservative.
Any space allocated via @code{alloca}, variable-length arrays, or related
constructs is included by the compiler when determining whether or not to
@end smallexample
@end itemize
+@option{-Wstack-usage=}@samp{PTRDIFF_MAX} is enabled by default.
+Warnings controlled by the option can be disabled either by specifying
+@var{byte-size} of @samp{SIZE_MAX} or more or by
+@option{-Wno-stack-usage}.
+
+@item -Wno-stack-usage
+@opindex Wno-stack-usage
+Disable @option{-Wstack-usage=} warnings. The option is equivalent
+to @option{-Wstack-usage=}@samp{SIZE_MAX} or larger.
+
@item -Wunsafe-loop-optimizations
@opindex Wunsafe-loop-optimizations
@opindex Wno-unsafe-loop-optimizations
@item -Wc++-compat @r{(C and Objective-C only)}
@opindex Wc++-compat
+@opindex Wno-c++-compat
Warn about ISO C constructs that are outside of the common subset of
ISO C and ISO C++, e.g.@: request for implicit conversion from
@code{void *} to a pointer to non-@code{void} type.
@item -Wc++11-compat @r{(C++ and Objective-C++ only)}
@opindex Wc++11-compat
+@opindex Wno-c++11-compat
Warn about C++ constructs whose meaning differs between ISO C++ 1998
and ISO C++ 2011, e.g., identifiers in ISO C++ 1998 that are keywords
in ISO C++ 2011. This warning turns on @option{-Wnarrowing} and is
@item -Wc++14-compat @r{(C++ and Objective-C++ only)}
@opindex Wc++14-compat
+@opindex Wno-c++14-compat
Warn about C++ constructs whose meaning differs between ISO C++ 2011
and ISO C++ 2014. This warning is enabled by @option{-Wall}.
@item -Wc++17-compat @r{(C++ and Objective-C++ only)}
@opindex Wc++17-compat
+@opindex Wno-c++17-compat
Warn about C++ constructs whose meaning differs between ISO C++ 2014
and ISO C++ 2017. This warning is enabled by @option{-Wall}.
Requires @option{-flto-odr-type-merging} to be enabled. Enabled by default.
@item -Wopenmp-simd
-@opindex Wopenm-simd
-Warn if the vectorizer cost model overrides the OpenMP or the Cilk Plus
+@opindex Wopenmp-simd
+@opindex Wno-openmp-simd
+Warn if the vectorizer cost model overrides the OpenMP
simd directive set by user. The @option{-fsimd-cost-model=unlimited}
option can be used to relax the cost model.
the call is diagnosed.
@smallexample
-struct foo
+void foo (void)
@{
char a[] = "abcd1234";
strcpy (a, a + 4);
-@};
+ @dots{}
+@}
@end smallexample
-The @option{-Wrestrict} is included in @option{-Wall}.
+The @option{-Wrestrict} option detects some instances of simple overlap
+even without optimization but works best at @option{-O2} and above. It
+is included in @option{-Wall}.
@item -Wnested-externs @r{(C and Objective-C only)}
@opindex Wnested-externs
@option{-Wno-vla} prevents the @option{-Wpedantic} warning of
the variable-length array.
-@item -Wvla-larger-than=@var{n}
-If this option is used, the compiler will warn on uses of
-variable-length arrays where the size is either unbounded, or bounded
-by an argument that can be larger than @var{n} bytes. This is similar
-to how @option{-Walloca-larger-than=@var{n}} works, but with
-variable-length arrays.
+@item -Wvla-larger-than=@var{byte-size}
+@opindex -Wvla-larger-than=
+@opindex -Wno-vla-larger-than
+If this option is used, the compiler will warn for declarations of
+variable-length arrays whose size is either unbounded, or bounded
+by an argument that allows the array size to exceed @var{byte-size}
+bytes. This is similar to how @option{-Walloca-larger-than=}@var{byte-size}
+works, but with variable-length arrays.
Note that GCC may optimize small variable-length arrays of a known
value into plain arrays, so this warning may not get triggered for
such arrays.
-This warning is not enabled by @option{-Wall}, and is only active when
-@option{-ftree-vrp} is active (default for @option{-O2} and above).
+@option{-Wvla-larger-than=}@samp{PTRDIFF_MAX} is enabled by default but
+is typically only effective when @option{-ftree-vrp} is active (default
+for @option{-O2} and above).
+
+See also @option{-Walloca-larger-than=@var{byte-size}}.
-See also @option{-Walloca-larger-than=@var{n}}.
+@item -Wno-vla-larger-than
+@opindex Wno-vla-larger-than
+Disable @option{-Wvla-larger-than=} warnings. The option is equivalent
+to @option{-Wvla-larger-than=}@samp{SIZE_MAX} or larger.
@item -Wvolatile-register-var
@opindex Wvolatile-register-var
@item -Wunsuffixed-float-constants @r{(C and Objective-C only)}
@opindex Wunsuffixed-float-constants
+@opindex Wno-unsuffixed-float-constants
Issue a warning for any floating constant that does not have
a suffix. When used together with @option{-Wsystem-headers} it
When using DWARF Version 4 or higher, type DIEs can be put into
their own @code{.debug_types} section instead of making them part of the
@code{.debug_info} section. It is more efficient to put them in a separate
-comdat sections since the linker can then remove duplicates.
+comdat section since the linker can then remove duplicates.
But not all DWARF consumers support @code{.debug_types} sections yet
and on some objects @code{.debug_types} produces larger instead of smaller
debugging information.
@item -grecord-gcc-switches
-@item -gno-record-gcc-switches
+@itemx -gno-record-gcc-switches
@opindex grecord-gcc-switches
@opindex gno-record-gcc-switches
This switch causes the command-line options used to invoke the
Allow using extensions of later DWARF standard version than selected with
@option{-gdwarf-@var{version}}.
+@item -gas-loc-support
+@opindex gas-loc-support
+Inform the compiler that the assembler supports @code{.loc} directives.
+It may then use them for the assembler to generate DWARF2+ line number
+tables.
+
+This is generally desirable, because assembler-generated line-number
+tables are a lot more compact than those the compiler can generate
+itself.
+
+This option will be enabled by default if, at GCC configure time, the
+assembler was found to support such directives.
+
+@item -gno-as-loc-support
+@opindex gno-as-loc-support
+Force GCC to generate DWARF2+ line number tables internally, if DWARF2+
+line number tables are to be generated.
+
+@item gas-locview-support
+@opindex gas-locview-support
+Inform the compiler that the assembler supports @code{view} assignment
+and reset assertion checking in @code{.loc} directives.
+
+This option will be enabled by default if, at GCC configure time, the
+assembler was found to support them.
+
+@item gno-as-locview-support
+Force GCC to assign view numbers internally, if
+@option{-gvariable-location-views} are explicitly requested.
+
@item -gcolumn-info
-@item -gno-column-info
+@itemx -gno-column-info
@opindex gcolumn-info
@opindex gno-column-info
Emit location column information into DWARF debugging information, rather
This option is enabled by default.
@item -gstatement-frontiers
-@item -gno-statement-frontiers
+@itemx -gno-statement-frontiers
@opindex gstatement-frontiers
@opindex gno-statement-frontiers
This option causes GCC to create markers in the internal representation
compiling with optimization (@option{-Os}, @option{-O}, @option{-O2},
@dots{}), and outputting DWARF 2 debug information at the normal level.
+@item -gvariable-location-views
+@itemx -gvariable-location-views=incompat5
+@itemx -gno-variable-location-views
+@opindex gvariable-location-views
+@opindex gvariable-location-views=incompat5
+@opindex gno-variable-location-views
+Augment variable location lists with progressive view numbers implied
+from the line number table. This enables debug information consumers to
+inspect state at certain points of the program, even if no instructions
+associated with the corresponding source locations are present at that
+point. If the assembler lacks support for view numbers in line number
+tables, this will cause the compiler to emit the line number table,
+which generally makes them somewhat less compact. The augmented line
+number tables and location lists are fully backward-compatible, so they
+can be consumed by debug information consumers that are not aware of
+these augmentations, but they won't derive any benefit from them either.
+
+This is enabled by default when outputting DWARF 2 debug information at
+the normal level, as long as there is assembler support,
+@option{-fvar-tracking-assignments} is enabled and
+@option{-gstrict-dwarf} is not. When assembler support is not
+available, this may still be enabled, but it will force GCC to output
+internal line number tables, and if
+@option{-ginternal-reset-location-views} is not enabled, that will most
+certainly lead to silently mismatching location views.
+
+There is a proposed representation for view numbers that is not backward
+compatible with the location list format introduced in DWARF 5, that can
+be enabled with @option{-gvariable-location-views=incompat5}. This
+option may be removed in the future, is only provided as a reference
+implementation of the proposed representation. Debug information
+consumers are not expected to support this extended format, and they
+would be rendered unable to decode location lists using it.
+
+@item -ginternal-reset-location-views
+@itemx -gnointernal-reset-location-views
+@opindex ginternal-reset-location-views
+@opindex gno-internal-reset-location-views
+Attempt to determine location views that can be omitted from location
+view lists. This requires the compiler to have very accurate insn
+length estimates, which isn't always the case, and it may cause
+incorrect view lists to be generated silently when using an assembler
+that does not support location view lists. The GNU assembler will flag
+any such error as a @code{view number mismatch}. This is only enabled
+on ports that define a reliable estimation function.
+
+@item -ginline-points
+@itemx -gno-inline-points
+@opindex ginline-points
+@opindex gno-inline-points
+Generate extended debug information for inlined functions. Location
+view tracking markers are inserted at inlined entry points, so that
+address and view numbers can be computed and output in debug
+information. This can be enabled independently of location views, in
+which case the view numbers won't be output, but it can only be enabled
+along with statement frontiers, and it is only enabled by default if
+location views are enabled.
+
@item -gz@r{[}=@var{type}@r{]}
@opindex gz
Produce compressed debug sections in DWARF format, if that is supported.
-ftree-loop-distribution @gol
-ftree-loop-distribute-patterns @gol
-floop-interchange @gol
+-floop-unroll-and-jam @gol
-fsplit-paths @gol
-ftree-slp-vectorize @gol
-fvect-cost-model @gol
in this way. This inlining applies to all functions, even those not declared
inline.
-Enabled at level @option{-O2}.
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
@item -findirect-inlining
@opindex findirect-inlining
when inlining itself is turned on by the @option{-finline-functions}
or @option{-finline-small-functions} options.
-Enabled at level @option{-O2}.
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
@item -finline-functions
@opindex finline-functions
declared @code{static}, then the function is normally not output as
assembler code in its own right.
-Enabled at level @option{-O3}.
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
@item -finline-functions-called-once
@opindex finline-functions-called-once
@item -fisolate-erroneous-paths-attribute
@opindex fisolate-erroneous-paths-attribute
-Detect paths that trigger erroneous or undefined behavior due a null value
+Detect paths that trigger erroneous or undefined behavior due to a null value
being used in a way forbidden by a @code{returns_nonnull} or @code{nonnull}
attribute. Isolate those paths from the main control flow and turn the
statement with erroneous or undefined behavior into a trap. This is not
@item -ftree-builtin-call-dce
@opindex ftree-builtin-call-dce
Perform conditional dead code elimination (DCE) for calls to built-in functions
-that may set @code{errno} but are otherwise side-effect free. This flag is
+that may set @code{errno} but are otherwise free of side effects. This flag is
enabled by default at @option{-O2} and higher if @option{-Os} is not also
specified.
for (int j = 0; j < N; j++)
c[i][j] = c[i][j] + a[i][k]*b[k][j];
@end smallexample
+This flag is enabled by default at @option{-O3}.
+
+@item -floop-unroll-and-jam
+@opindex floop-unroll-and-jam
+Apply unroll and jam transformations on feasible loops. In a loop
+nest this unrolls the outer loop by some factor and fuses the resulting
+multiple inner loops. This flag is enabled by default at @option{-O3}.
@item -ftree-loop-im
@opindex ftree-loop-im
@item -fsimd-cost-model=@var{model}
@opindex fsimd-cost-model
Alter the cost model used for vectorization of loops marked with the OpenMP
-or Cilk Plus simd directive. The @var{model} argument should be one of
+simd directive. The @var{model} argument should be one of
@samp{unlimited}, @samp{dynamic}, @samp{cheap}. All values of @var{model}
have the same meaning as described in @option{-fvect-cost-model} and by
default a cost model defined with @option{-fvect-cost-model} is used.
when inlining itself is turned on by the @option{-finline-functions}
or @option{-finline-small-functions} options.
-Enabled at level @option{-O2}.
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.
@item -fpredictive-commoning
@opindex fpredictive-commoning
@end smallexample
The @option{-fprintf-return-value} option relies on other optimizations
-and yields best results with @option{-O2}. It works in tandem with the
-@option{-Wformat-overflow} and @option{-Wformat-truncation} options.
-The @option{-fprintf-return-value} option is enabled by default.
+and yields best results with @option{-O2} and above. It works in tandem
+with the @option{-Wformat-overflow} and @option{-Wformat-truncation}
+options. The @option{-fprintf-return-value} option is enabled by default.
@item -fno-peephole
@itemx -fno-peephole2
enabled by default (to avoid linker errors), but may be enabled
explicitly (if using a working linker).
-Enabled for x86 at levels @option{-O2}, @option{-O3}.
+Enabled for x86 at levels @option{-O2}, @option{-O3}, @option{-Os}.
@item -freorder-functions
@opindex freorder-functions
@item -falign-functions
@itemx -falign-functions=@var{n}
+@itemx -falign-functions=@var{n}:@var{m}
+@itemx -falign-functions=@var{n}:@var{m}:@var{n2}
+@itemx -falign-functions=@var{n}:@var{m}:@var{n2}:@var{m2}
@opindex falign-functions
Align the start of functions to the next power-of-two greater than
-@var{n}, skipping up to @var{n} bytes. For instance,
-@option{-falign-functions=32} aligns functions to the next 32-byte
-boundary, but @option{-falign-functions=24} aligns to the next
-32-byte boundary only if this can be done by skipping 23 bytes or less.
+@var{n}, skipping up to @var{m}-1 bytes. This ensures that at least
+the first @var{m} bytes of the function can be fetched by the CPU
+without crossing an @var{n}-byte alignment boundary.
-@option{-fno-align-functions} and @option{-falign-functions=1} are
-equivalent and mean that functions are not aligned.
+If @var{m} is not specified, it defaults to @var{n}.
+
+Examples: @option{-falign-functions=32} aligns functions to the next
+32-byte boundary, @option{-falign-functions=24} aligns to the next
+32-byte boundary only if this can be done by skipping 23 bytes or less,
+@option{-falign-functions=32:7} aligns to the next
+32-byte boundary only if this can be done by skipping 6 bytes or less.
+
+The second pair of @var{n2}:@var{m2} values allows you to specify
+a secondary alignment: @option{-falign-functions=64:7:32:3} aligns to
+the next 64-byte boundary if this can be done by skipping 6 bytes or less,
+otherwise aligns to the next 32-byte boundary if this can be done
+by skipping 2 bytes or less.
+If @var{m2} is not specified, it defaults to @var{n2}.
Some assemblers only support this flag when @var{n} is a power of two;
in that case, it is rounded up.
+@option{-fno-align-functions} and @option{-falign-functions=1} are
+equivalent and mean that functions are not aligned.
+
If @var{n} is not specified or is zero, use a machine-dependent default.
+The maximum allowed @var{n} option value is 65536.
Enabled at levels @option{-O2}, @option{-O3}.
@item -falign-labels
@itemx -falign-labels=@var{n}
+@itemx -falign-labels=@var{n}:@var{m}
+@itemx -falign-labels=@var{n}:@var{m}:@var{n2}
+@itemx -falign-labels=@var{n}:@var{m}:@var{n2}:@var{m2}
@opindex falign-labels
-Align all branch targets to a power-of-two boundary, skipping up to
-@var{n} bytes like @option{-falign-functions}. This option can easily
-make code slower, because it must insert dummy operations for when the
-branch target is reached in the usual flow of the code.
+Align all branch targets to a power-of-two boundary.
+Parameters of this option are analogous to the @option{-falign-functions} option.
@option{-fno-align-labels} and @option{-falign-labels=1} are
equivalent and mean that labels are not aligned.
If @var{n} is not specified or is zero, use a machine-dependent default
which is very likely to be @samp{1}, meaning no alignment.
+The maximum allowed @var{n} option value is 65536.
Enabled at levels @option{-O2}, @option{-O3}.
@item -falign-loops
@itemx -falign-loops=@var{n}
+@itemx -falign-loops=@var{n}:@var{m}
+@itemx -falign-loops=@var{n}:@var{m}:@var{n2}
+@itemx -falign-loops=@var{n}:@var{m}:@var{n2}:@var{m2}
@opindex falign-loops
-Align loops to a power-of-two boundary, skipping up to @var{n} bytes
-like @option{-falign-functions}. If the loops are
-executed many times, this makes up for any execution of the dummy
-operations.
+Align loops to a power-of-two boundary. If the loops are executed
+many times, this makes up for any execution of the dummy padding
+instructions.
+Parameters of this option are analogous to the @option{-falign-functions} option.
@option{-fno-align-loops} and @option{-falign-loops=1} are
equivalent and mean that loops are not aligned.
+The maximum allowed @var{n} option value is 65536.
If @var{n} is not specified or is zero, use a machine-dependent default.
@item -falign-jumps
@itemx -falign-jumps=@var{n}
+@itemx -falign-jumps=@var{n}:@var{m}
+@itemx -falign-jumps=@var{n}:@var{m}:@var{n2}
+@itemx -falign-jumps=@var{n}:@var{m}:@var{n2}:@var{m2}
@opindex falign-jumps
Align branch targets to a power-of-two boundary, for branch targets
-where the targets can only be reached by jumping, skipping up to @var{n}
-bytes like @option{-falign-functions}. In this case, no dummy operations
-need be executed.
+where the targets can only be reached by jumping. In this case,
+no dummy operations need be executed.
+Parameters of this option are analogous to the @option{-falign-functions} option.
@option{-fno-align-jumps} and @option{-falign-jumps=1} are
equivalent and mean that loops are not aligned.
If @var{n} is not specified or is zero, use a machine-dependent default.
+The maximum allowed @var{n} option value is 65536.
Enabled at levels @option{-O2}, @option{-O3}.
and @command{ranlib};
to show the symbols of object files with GIMPLE bytecode, use
@command{gcc-nm}. Those commands require that @command{ar}, @command{ranlib}
-and @command{nm} have been compiled with plugin support. At link time, use the the
+and @command{nm} have been compiled with plugin support. At link time, use the
flag @option{-fuse-linker-plugin} to ensure that the library participates in
the LTO optimization process:
GCC do not work with an older or newer version of GCC.
Link-time optimization does not work well with generation of debugging
-information. Combining @option{-flto} with
-@option{-g} is currently experimental and expected to produce unexpected
-results.
+information on systems other than those using a combination of ELF and
+DWARF.
If you specify the optional @var{n}, the optimization and code
generation done at link time is executed in parallel using @var{n}
@command{gcc-nm}, @command{gcc-ranlib} wrappers to pass the right options
to these tools. With non fat LTO makefiles need to be modified to use them.
+Note that modern binutils provide plugin auto-load mechanism.
+Installing the linker plugin into @file{$libdir/bfd-plugins} has the same
+effect as usage of the command wrappers (@command{gcc-ar}, @command{gcc-nm} and
+@command{gcc-ranlib}).
+
The default is @option{-fno-fat-lto-objects} on targets with linker plugin
support.
Move branches with loop invariant conditions out of the loop, with duplicates
of the loop on both branches (modified according to result of the condition).
-@item -floop-unroll-and-jam
-@opindex floop-unroll-and-jam
-Apply unroll and jam transformations on feasible loops. In a loop
-nest this unrolls the outer loop by some factor and fuses the resulting
-multiple inner loops.
-
@item -ffunction-sections
@itemx -fdata-sections
@opindex ffunction-sections
profitable.
@item max-rtl-if-conversion-predictable-cost
-@item max-rtl-if-conversion-unpredictable-cost
+@itemx max-rtl-if-conversion-unpredictable-cost
RTL if-conversion will try to remove conditional branches around a block
and replace them with conditionally executed instructions. These parameters
give the maximum permissible cost for the sequence that would be generated
by the compiler are investigated. To those functions, a different
(more restrictive) limit compared to functions declared inline can
be applied.
-The default value is 40.
+The default value is 30.
@item inline-min-speedup
When estimated performance improvement of caller + callee runtime exceeds this
threshold (in percent), the function can be inlined regardless of the limit on
@option{--param max-inline-insns-single} and @option{--param
max-inline-insns-auto}.
+The default value is 15.
@item large-function-insns
The limit specifying really large functions. For functions larger than this
Maximum size (in bytes) of objects tracked bytewise by dead store elimination.
Larger values may result in larger compilation times.
+@item dse-max-alias-queries-per-store
+Maximum number of queries into the alias oracle per store.
+Larger values result in larger compilation times and may result in more
+removed dead stores.
+
@item scev-max-expr-size
Bound on size of expressions used in the scalar evolutions analyzer.
Large expressions slow the analyzer.
parameter takes a percentage (i.e. 0 ... 100) as input.
The default probability of 90 is obtained empirically.
+@item builtin-string-cmp-inline-length
+The maximum length of a constant string for a builtin string cmp call
+eligible for inlining.
+The default value is 3.
+
@item align-threshold
Select fraction of the maximal frequency of executions of a basic block in
@item l2-cache-size
The size of L2 cache, in kilobytes.
+@item prefetch-dynamic-strides
+Whether the loop array prefetch pass should issue software prefetch hints
+for strides that are non-constant. In some cases this may be
+beneficial, though the fact the stride is non-constant may make it
+hard to predict when there is clear benefit to issuing these hints.
+
+Set to 1, the default, if the prefetch hints should be issued for non-constant
+strides. Set to 0 if prefetch hints should be issued only for strides that
+are known to be constant and below @option{prefetch-minimum-stride}.
+
+@item prefetch-minimum-stride
+Minimum constant stride, in bytes, to start using prefetch hints for. If
+the stride is less than this threshold, prefetch hints will not be issued.
+
+This setting is useful for processors that have hardware prefetchers, in
+which case there may be conflicts between the hardware prefetchers and
+the software prefetchers. If the hardware prefetchers have a maximum
+stride they can handle, it should be used here to improve the use of
+software prefetchers.
+
+A value of -1, the default, means we don't have a threshold and therefore
+prefetch hints can be issued for any constant stride.
+
+This setting is only useful for strides that are known and constant.
+
@item loop-interchange-max-num-stmts
The maximum number of stmts in a loop to be interchanged.
pointer parameter.
@item sra-max-scalarization-size-Ospeed
-@item sra-max-scalarization-size-Osize
+@itemx sra-max-scalarization-size-Osize
The two Scalar Reduction of Aggregates passes (SRA and IPA-SRA) aim to
replace scalar parts of aggregates with uses of independent scalar
variables. These parameters control the maximum size, in storage units,
number, directly poison (or unpoison) shadow memory instead of using
run-time callbacks. The default value is 256.
-@item chkp-max-ctor-size
-Static constructors generated by Pointer Bounds Checker may become very
-large and significantly increase compile time at optimization level
-@option{-O1} and higher. This parameter is a maximum number of statements
-in a single generated constructor. Default value is 5000.
-
@item max-fsm-thread-path-insns
Maximum number of instructions to copy when duplicating blocks on a
finite state automaton jump thread path. The default is 100.
and its related options. Both absolute and relative paths can be used.
By default, GCC uses the current directory as @var{path}, thus the
profile data file appears in the same directory as the object file.
+In order to prevent the file name clashing, if the object file name is
+not an absolute path, we mangle the absolute path of the
+@file{@var{sourcename}.gcda} file and use it as the file name of a
+@file{.gcda} file.
+
+When an executable is run in a massive parallel environment, it is recommended
+to save profile to different folders. That can be done with variables
+in @var{path} that are exported during run-time:
+
+@table @gcctabopt
+
+@item %p
+process ID.
+
+@item %q@{VAR@}
+value of environment variable @var{VAR}
+
+@end table
@item -fprofile-generate
@itemx -fprofile-generate=@var{path}
the available options are shown at startup of the instrumented program. See
@url{https://github.com/google/sanitizers/wiki/AddressSanitizerFlags#run-time-flags}
for a list of supported options.
-The option cannot be combined with @option{-fsanitize=thread}
-and/or @option{-fcheck-pointer-bounds}.
+The option cannot be combined with @option{-fsanitize=thread}.
@item -fsanitize=kernel-address
@opindex fsanitize=kernel-address
Enable AddressSanitizer for Linux kernel.
See @uref{https://github.com/google/kasan/wiki} for more details.
-The option cannot be combined with @option{-fcheck-pointer-bounds}.
@item -fsanitize=pointer-compare
@opindex fsanitize=pointer-compare
Instrument comparison operation (<, <=, >, >=) with pointer operands.
The option must be combined with either @option{-fsanitize=kernel-address} or
@option{-fsanitize=address}
-The option cannot be combined with @option{-fsanitize=thread}
-and/or @option{-fcheck-pointer-bounds}.
+The option cannot be combined with @option{-fsanitize=thread}.
Note: By default the check is disabled at run time. To enable it,
add @code{detect_invalid_pointer_pairs=2} to the environment variable
@env{ASAN_OPTIONS}. Using @code{detect_invalid_pointer_pairs=1} detects
Instrument subtraction with pointer operands.
The option must be combined with either @option{-fsanitize=kernel-address} or
@option{-fsanitize=address}
-The option cannot be combined with @option{-fsanitize=thread}
-and/or @option{-fcheck-pointer-bounds}.
+The option cannot be combined with @option{-fsanitize=thread}.
Note: By default the check is disabled at run time. To enable it,
add @code{detect_invalid_pointer_pairs=2} to the environment variable
@env{ASAN_OPTIONS}. Using @code{detect_invalid_pointer_pairs=1} detects
@url{https://github.com/google/sanitizers/wiki/ThreadSanitizerFlags} for a list of
supported options.
The option cannot be combined with @option{-fsanitize=address},
-@option{-fsanitize=leak} and/or @option{-fcheck-pointer-bounds}.
+@option{-fsanitize=leak}.
Note that sanitized atomic builtins cannot throw exceptions when
operating on invalid memory addresses with non-call exceptions
This option enables instrumentation of array bounds. Various out of bounds
accesses are detected. Flexible array members, flexible array member-like
arrays, and initializers of variables with static storage are not instrumented.
-The option cannot be combined with @option{-fcheck-pointer-bounds}.
@item -fsanitize=bounds-strict
@opindex fsanitize=bounds-strict
This option enables strict instrumentation of array bounds. Most out of bounds
accesses are detected, including flexible array members and flexible array
member-like arrays. Initializers of variables with static storage are not
-instrumented. The option cannot be combined
-with @option{-fcheck-pointer-bounds}.
+instrumented.
@item -fsanitize=alignment
@opindex fsanitize=alignment
@code{__sanitizer_cov_trace_cmpd} for float or double comparisons and
@code{__sanitizer_cov_trace_switch} for switch statements.
-@item -fbounds-check
-@opindex fbounds-check
-For front ends that support it, generate additional code to check that
-indices used to access arrays are within the declared range. This is
-currently only supported by the Fortran front end, where this option
-defaults to false.
-
-@item -fcheck-pointer-bounds
-@opindex fcheck-pointer-bounds
-@opindex fno-check-pointer-bounds
-@cindex Pointer Bounds Checker options
-Enable Pointer Bounds Checker instrumentation. Each memory reference
-is instrumented with checks of the pointer used for memory access against
-bounds associated with that pointer.
-
-Currently there
-is only an implementation for Intel MPX available, thus x86 GNU/Linux target
-and @option{-mmpx} are required to enable this feature.
-MPX-based instrumentation requires
-a runtime library to enable MPX in hardware and handle bounds
-violation signals. By default when @option{-fcheck-pointer-bounds}
-and @option{-mmpx} options are used to link a program, the GCC driver
-links against the @file{libmpx} and @file{libmpxwrappers} libraries.
-Bounds checking on calls to dynamic libraries requires a linker
-with @option{-z bndplt} support; if GCC was configured with a linker
-without support for this option (including the Gold linker and older
-versions of ld), a warning is given if you link with @option{-mmpx}
-without also specifying @option{-static}, since the overall effectiveness
-of the bounds checking protection is reduced.
-See also @option{-static-libmpxwrappers}.
-
-MPX-based instrumentation
-may be used for debugging and also may be included in production code
-to increase program security. Depending on usage, you may
-have different requirements for the runtime library. The current version
-of the MPX runtime library is more oriented for use as a debugging
-tool. MPX runtime library usage implies @option{-lpthread}. See
-also @option{-static-libmpx}. The runtime library behavior can be
-influenced using various @env{CHKP_RT_*} environment variables. See
-@uref{https://gcc.gnu.org/wiki/Intel%20MPX%20support%20in%20the%20GCC%20compiler}
-for more details.
-
-Generated instrumentation may be controlled by various
-@option{-fchkp-*} options and by the @code{bnd_variable_size}
-structure field attribute (@pxref{Type Attributes}) and
-@code{bnd_legacy}, and @code{bnd_instrument} function attributes
-(@pxref{Function Attributes}). GCC also provides a number of built-in
-functions for controlling the Pointer Bounds Checker. @xref{Pointer
-Bounds Checker builtins}, for more information.
-
-@item -fchkp-check-incomplete-type
-@opindex fchkp-check-incomplete-type
-@opindex fno-chkp-check-incomplete-type
-Generate pointer bounds checks for variables with incomplete type.
-Enabled by default.
-
-@item -fchkp-narrow-bounds
-@opindex fchkp-narrow-bounds
-@opindex fno-chkp-narrow-bounds
-Controls bounds used by Pointer Bounds Checker for pointers to object
-fields. If narrowing is enabled then field bounds are used. Otherwise
-object bounds are used. See also @option{-fchkp-narrow-to-innermost-array}
-and @option{-fchkp-first-field-has-own-bounds}. Enabled by default.
-
-@item -fchkp-first-field-has-own-bounds
-@opindex fchkp-first-field-has-own-bounds
-@opindex fno-chkp-first-field-has-own-bounds
-Forces Pointer Bounds Checker to use narrowed bounds for the address of the
-first field in the structure. By default a pointer to the first field has
-the same bounds as a pointer to the whole structure.
-
-@item -fchkp-flexible-struct-trailing-arrays
-@opindex fchkp-flexible-struct-trailing-arrays
-@opindex fno-chkp-flexible-struct-trailing-arrays
-Forces Pointer Bounds Checker to treat all trailing arrays in structures as
-possibly flexible. By default only array fields with zero length or that are
-marked with attribute bnd_variable_size are treated as flexible.
-
-@item -fchkp-narrow-to-innermost-array
-@opindex fchkp-narrow-to-innermost-array
-@opindex fno-chkp-narrow-to-innermost-array
-Forces Pointer Bounds Checker to use bounds of the innermost arrays in
-case of nested static array access. By default this option is disabled and
-bounds of the outermost array are used.
-
-@item -fchkp-optimize
-@opindex fchkp-optimize
-@opindex fno-chkp-optimize
-Enables Pointer Bounds Checker optimizations. Enabled by default at
-optimization levels @option{-O}, @option{-O2}, @option{-O3}.
-
-@item -fchkp-use-fast-string-functions
-@opindex fchkp-use-fast-string-functions
-@opindex fno-chkp-use-fast-string-functions
-Enables use of @code{*_nobnd} versions of string functions (not copying bounds)
-by Pointer Bounds Checker. Disabled by default.
-
-@item -fchkp-use-nochk-string-functions
-@opindex fchkp-use-nochk-string-functions
-@opindex fno-chkp-use-nochk-string-functions
-Enables use of @code{*_nochk} versions of string functions (not checking bounds)
-by Pointer Bounds Checker. Disabled by default.
-
-@item -fchkp-use-static-bounds
-@opindex fchkp-use-static-bounds
-@opindex fno-chkp-use-static-bounds
-Allow Pointer Bounds Checker to generate static bounds holding
-bounds of static variables. Enabled by default.
-
-@item -fchkp-use-static-const-bounds
-@opindex fchkp-use-static-const-bounds
-@opindex fno-chkp-use-static-const-bounds
-Use statically-initialized bounds for constant bounds instead of
-generating them each time they are required. By default enabled when
-@option{-fchkp-use-static-bounds} is enabled.
-
-@item -fchkp-treat-zero-dynamic-size-as-infinite
-@opindex fchkp-treat-zero-dynamic-size-as-infinite
-@opindex fno-chkp-treat-zero-dynamic-size-as-infinite
-With this option, objects with incomplete type whose
-dynamically-obtained size is zero are treated as having infinite size
-instead by Pointer Bounds
-Checker. This option may be helpful if a program is linked with a library
-missing size information for some symbols. Disabled by default.
-
-@item -fchkp-check-read
-@opindex fchkp-check-read
-@opindex fno-chkp-check-read
-Instructs Pointer Bounds Checker to generate checks for all read
-accesses to memory. Enabled by default.
-
-@item -fchkp-check-write
-@opindex fchkp-check-write
-@opindex fno-chkp-check-write
-Instructs Pointer Bounds Checker to generate checks for all write
-accesses to memory. Enabled by default.
-
-@item -fchkp-store-bounds
-@opindex fchkp-store-bounds
-@opindex fno-chkp-store-bounds
-Instructs Pointer Bounds Checker to generate bounds stores for
-pointer writes. Enabled by default.
-
-@item -fchkp-instrument-calls
-@opindex fchkp-instrument-calls
-@opindex fno-chkp-instrument-calls
-Instructs Pointer Bounds Checker to pass pointer bounds to calls.
-Enabled by default.
-
-@item -fchkp-instrument-marked-only
-@opindex fchkp-instrument-marked-only
-@opindex fno-chkp-instrument-marked-only
-Instructs Pointer Bounds Checker to instrument only functions
-marked with the @code{bnd_instrument} attribute
-(@pxref{Function Attributes}). Disabled by default.
-
-@item -fchkp-use-wrappers
-@opindex fchkp-use-wrappers
-@opindex fno-chkp-use-wrappers
-Allows Pointer Bounds Checker to replace calls to built-in functions
-with calls to wrapper functions. When @option{-fchkp-use-wrappers}
-is used to link a program, the GCC driver automatically links
-against @file{libmpxwrappers}. See also @option{-static-libmpxwrappers}.
-Enabled by default.
-
-@item -fcf-protection==@r{[}full@r{|}branch@r{|}return@r{|}none@r{]}
+@item -fcf-protection=@r{[}full@r{|}branch@r{|}return@r{|}none@r{]}
@opindex fcf-protection
Enable code instrumentation of control-flow transfers to increase
program security by checking that target addresses of control-flow
@code{branch} and @code{return}. The value @code{none} turns off
instrumentation.
+The macro @code{__CET__} is defined when @option{-fcf-protection} is
+used. The first bit of @code{__CET__} is set to 1 for the value
+@code{branch} and the second bit of @code{__CET__} is set to 1 for
+the @code{return}.
+
You can also use the @code{nocf_check} attribute to identify
which functions and calls should be skipped from instrumentation
(@pxref{Function Attributes}).
Currently the x86 GNU/Linux target provides an implementation based
-on Intel Control-flow Enforcement Technology (CET). Instrumentation
-for x86 is controlled by target-specific options @option{-mcet},
-@option{-mibt} and @option{-mshstk} (@pxref{x86 Options}).
+on Intel Control-flow Enforcement Technology (CET).
@item -fstack-protector
@opindex fstack-protector
object file names should not be used as arguments. @xref{Overall
Options}.
+@item -flinker-output=@var{type}
+@opindex -flinker-output
+This option controls the code generation of the link time optimizer. By
+default the linker output is determined by the linker plugin automatically. For
+debugging the compiler and in the case of incremental linking to non-lto object
+file is desired, it may be useful to control the type manually.
+
+If @var{type} is @samp{exec} the code generation is configured to produce static
+binary. In this case @option{-fpic} and @option{-fpie} are both disabled.
+
+If @var{type} is @samp{dyn} the code generation is configured to produce shared
+library. In this case @option{-fpic} or @option{-fPIC} is preserved, but not
+enabled automatically. This makes it possible to build shared libraries without
+position independent code on architectures this is possible, i.e. on x86.
+
+If @var{type} is @samp{pie} the code generation is configured to produce
+@option{-fpie} executable. This result in similar optimizations as @samp{exec}
+except that @option{-fpie} is not disabled if specified at compilation time.
+
+If @var{type} is @samp{rel} the compiler assumes that incremental linking is
+done. The sections containing intermediate code for link-time optimization are
+merged, pre-optimized, and output to the resulting object file. In addition, if
+@option{-ffat-lto-objects} is specified the binary code is produced for future
+non-lto linking. The object file produced by incremental linking will be smaller
+than a static library produced from the same object files. At link-time the
+result of incremental linking will also load faster to compiler than a static
+library assuming that majority of objects in the library are used.
+
+Finally @samp{nolto-rel} configure compiler to for incremental linking where
+code generation is forced, final binary is produced and the intermediate code
+for later link-time optimization is stripped. When multiple object files are
+linked together the resulting code will be optimized better than with link time
+optimizations disabled (for example, the cross-module inlining will happen),
+most of benefits of whole program optimizations are however lost.
+
+During the incremental link (by @option{-r}) the linker plugin will default to
+@option{rel}. With current interfaces to GNU Binutils it is however not
+possible to link incrementally LTO objects and non-LTO objects into a single
+mixed object file. In the case any of object files in incremental link can not
+be used for link-time optimization the linker plugin will output warning and
+use @samp{nolto-rel}. To maintain the whole program optimization it is
+recommended to link such objects into static library instead. Alternatively it
+is possible to use H.J. Lu's binutils with support for mixed objects.
+
@item -fuse-ld=bfd
@opindex fuse-ld=bfd
Use the @command{bfd} linker instead of the default linker.
@item -nostartfiles
@opindex nostartfiles
Do not use the standard system startup files when linking.
-The standard system libraries are used normally, unless @option{-nostdlib}
-or @option{-nodefaultlibs} is used.
+The standard system libraries are used normally, unless @option{-nostdlib},
+@option{-nolibc}, or @option{-nodefaultlibs} is used.
@item -nodefaultlibs
@opindex nodefaultlibs
libc. These entry points should be supplied through some other
mechanism when this option is specified.
+@item -nolibc
+@opindex nolibc
+Do not use the C library or system libraries tightly coupled with it when
+linking. Still link with the startup files, @file{libgcc} or toolchain
+provided language support libraries such as @file{libgnat}, @file{libgfortran}
+or @file{libstdc++} unless options preventing their inclusion are used as
+well. This typically removes @option{-lc} from the link command line, as well
+as system libraries that normally go with it and become meaningless when
+absence of a C library is assumed, for example @option{-lpthread} or
+@option{-lm} in some configurations. This is intended for bare-board
+targets when there is indeed no C library available.
+
@item -nostdlib
@opindex nostdlib
Do not use the standard system startup files or libraries when linking.
driver to link @file{libubsan} statically, without necessarily linking
other libraries statically.
-@item -static-libmpx
-@opindex static-libmpx
-When the @option{-fcheck-pointer bounds} and @option{-mmpx} options are
-used to link a program, the GCC driver automatically links against
-@file{libmpx}. If @file{libmpx} is available as a shared library,
-and the @option{-static} option is not used, then this links against
-the shared version of @file{libmpx}. The @option{-static-libmpx}
-option directs the GCC driver to link @file{libmpx} statically,
-without necessarily linking other libraries statically.
-
-@item -static-libmpxwrappers
-@opindex static-libmpxwrappers
-When the @option{-fcheck-pointer bounds} and @option{-mmpx} options are used
-to link a program without also using @option{-fno-chkp-use-wrappers}, the
-GCC driver automatically links against @file{libmpxwrappers}. If
-@file{libmpxwrappers} is available as a shared library, and the
-@option{-static} option is not used, then this links against the shared
-version of @file{libmpxwrappers}. The @option{-static-libmpxwrappers}
-option directs the GCC driver to link @file{libmpxwrappers} statically,
-without necessarily linking other libraries statically.
-
@item -static-libstdc++
@opindex static-libstdc++
When the @command{g++} program is used to link a C++ program, it
@itemx -fPIE
@opindex fpie
@opindex fPIE
-These options are similar to @option{-fpic} and @option{-fPIC}, but
-generated position independent code can be only linked into executables.
-Usually these options are used when @option{-pie} GCC option is
-used during linking.
+These options are similar to @option{-fpic} and @option{-fPIC}, but the
+generated position-independent code can be only linked into executables.
+Usually these options are used to compile code that will be linked using
+the @option{-pie} GCC option.
@option{-fpie} and @option{-fPIE} both define the macros
@code{__pie__} and @code{__PIE__}. The macros have the value 1
rarely need to use any of these options for ordinary compilation and
linking tasks.
+Many developer options that cause GCC to dump output to a file take an
+optional @samp{=@var{filename}} suffix. You can specify @samp{stdout}
+or @samp{-} to dump to standard output, and @samp{stderr} for standard
+error.
+
+If @samp{=@var{filename}} is omitted, a default dump file name is
+constructed by concatenating the base dump file name, a pass number,
+phase letter, and pass name. The base dump file name is the name of
+output file produced by the compiler if explicitly specified and not
+an executable; otherwise it is the source file name.
+The pass number is determined by the order passes are registered with
+the compiler's pass manager.
+This is generally the same as the order of execution, but passes
+registered by plugins, target-specific passes, or passes that are
+otherwise registered late are numbered higher than the pass named
+@samp{final}, even if they are executed earlier. The phase letter is
+one of @samp{i} (inter-procedural analysis), @samp{l}
+(language-specific), @samp{r} (RTL), or @samp{t} (tree).
+The files are created in the directory of the output file.
+
@table @gcctabopt
@item -d@var{letters}
@opindex fdump-rtl-@var{pass}
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}, and the files are
-created in the directory of the output file. In case of
-@option{=@var{filename}} option, the dump is output on the given file
-instead of the pass numbered dump files. Note that the pass number is
-assigned as passes are registered into the pass manager. Most passes
-are registered in the order that they will execute and for these passes
-the number corresponds to the pass execution order. However, passes
-registered by plugins, passes specific to compilation targets, or
-passes that are otherwise registered after all the other passes are
-numbered higher than a pass named "final", even if they are executed
-earlier. @var{dumpname} is generated from the name of the output
-file if explicitly specified and not an executable, otherwise it is
-the basename of the source file.
+compiler.
Some @option{-d@var{letters}} switches have different meaning when
@option{-E} is used for preprocessing. @xref{Preprocessor Options},
@opindex fdump-tree-all
@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, and the file is
-created in the same directory as the output file. In case of
-@option{=@var{filename}} option, the dump is output on the given file
-instead of the auto named dump files. If the @samp{-@var{options}}
+language tree to a file. If the @samp{-@var{options}}
form is used, @var{options} is a list of @samp{-} separated options
which control the details of the dump. Not all options are applicable
to all dumps; those that are not meaningful are ignored. The
@item note
Enable other detailed optimization information (only available in
certain passes).
-@item =@var{filename}
-Instead of an auto named dump file, output into the given file
-name. The file names @file{stdout} and @file{stderr} are treated
-specially and are considered already open standard streams. For
-example,
-
-@smallexample
-gcc -O2 -ftree-vectorize -fdump-tree-vect-blocks=foo.dump
- -fdump-tree-pre=/dev/stderr file.c
-@end smallexample
-
-outputs vectorizer dump into @file{foo.dump}, while the PRE dump is
-output on to @file{stderr}. If two conflicting dump filenames are
-given for the same pass, then the latter option overrides the earlier
-one.
-
@item all
Turn on all options, except @option{raw}, @option{slim}, @option{verbose}
and @option{lineno}.
-
@item optall
Turn on all optimization options, i.e., @option{optimized},
@option{missed}, and @option{note}.
ignored. Thus only @file{vec.miss} is produced which contains
dumps from the vectorizer about missed opportunities.
+@item -fsave-optimization-record
+@opindex fsave-optimization-record
+Write a SRCFILE.opt-record.json file detailing what optimizations
+were performed, for those optimizations that support @option{-fopt-info}.
+
+This option is experimental and the format of the data within the JSON
+file is subject to change.
+
+It is roughly equivalent to a machine-readable version of
+@option{-fopt-info-all}, as a collection of messages with source file,
+line number and column number, with the following additional data for
+each message:
+
+@itemize @bullet
+
+@item
+the execution count of the code being optimized, along with metadata about
+whether this was from actual profile data, or just an estimate, allowing
+consumers to prioritize messages by code hotness,
+
+@item
+the function name of the code being optimized, where applicable,
+
+@item
+the ``inlining chain'' for the code being optimized, so that when
+a function is inlined into several different places (which might
+themselves be inlined), the reader can distinguish between the copies,
+
+@item
+objects identifying those parts of the message that refer to expressions,
+statements or symbol-table nodes, which of these categories they are, and,
+when available, their source code location,
+
+@item
+the GCC pass that emitted the message, and
+
+@item
+the location in GCC's own code from which the message was emitted
+
+@end itemize
+
+Additionally, some messages are logically nested within other
+messages, reflecting implementation details of the optimization
+passes.
+
@item -fsched-verbose=@var{n}
@opindex fsched-verbose
On targets that use instruction scheduling, this option controls the
@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
+silence warnings, and omitting other options that would cause the compiler
+to produce output to files or to standard output as a side effect. 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.
@item -fdbg-cnt=@var{counter-value-list}
@opindex fdbg-cnt
-Set the internal debug counter upper bound. @var{counter-value-list}
-is a comma-separated list of @var{name}:@var{value} pairs
-which sets the upper bound of each debug counter @var{name} to @var{value}.
+Set the internal debug counter lower and upper bound. @var{counter-value-list}
+is a comma-separated list of @var{name}:@var{lower_bound}:@var{upper_bound}
+tuples which sets the lower and the upper bound of each debug
+counter @var{name}. The @var{lower_bound} is optional and is zero
+initialized if not set.
All debug counters have the initial upper bound of @code{UINT_MAX};
thus @code{dbg_cnt} returns true always unless the upper bound
is set by this option.
-For example, with @option{-fdbg-cnt=dce:10,tail_call:0},
-@code{dbg_cnt(dce)} returns true only for first 10 invocations.
+For example, with @option{-fdbg-cnt=dce:2:4,tail_call:10},
+@code{dbg_cnt(dce)} returns true only for third and fourth invocation.
+For @code{dbg_cnt(tail_call)} true is returned for first 10 invocations.
@item -print-file-name=@var{library}
@opindex print-file-name
* PDP-11 Options::
* picoChip Options::
* PowerPC Options::
+* PowerPC SPE Options::
* RISC-V Options::
* RL78 Options::
* RS/6000 and PowerPC Options::
addresses and sizes of sections. Programs can be statically linked only.
@item -mstrict-align
+@itemx -mno-strict-align
@opindex mstrict-align
-Avoid generating memory accesses that may not be aligned on a natural object
-boundary as described in the architecture specification.
+@opindex mno-strict-align
+Avoid or allow generating memory accesses that may not be aligned on a natural
+object boundary as described in the architecture specification.
@item -momit-leaf-frame-pointer
@itemx -mno-omit-leaf-frame-pointer
corresponding flag to the linker.
@item -mlow-precision-recip-sqrt
-@item -mno-low-precision-recip-sqrt
+@itemx -mno-low-precision-recip-sqrt
@opindex mlow-precision-recip-sqrt
@opindex mno-low-precision-recip-sqrt
Enable or disable the reciprocal square root approximation.
single precision and to 32 bits for double precision.
@item -mlow-precision-sqrt
-@item -mno-low-precision-sqrt
+@itemx -mno-low-precision-sqrt
@opindex -mlow-precision-sqrt
@opindex -mno-low-precision-sqrt
Enable or disable the square root approximation.
If enabled, it implies @option{-mlow-precision-recip-sqrt}.
@item -mlow-precision-div
-@item -mno-low-precision-div
+@itemx -mno-low-precision-div
@opindex -mlow-precision-div
@opindex -mno-low-precision-div
Enable or disable the division approximation.
precision of division results to about 16 bits for
single precision and to 32 bits for double precision.
+@item -mtrack-speculation
+@itemx -mno-track-speculation
+Enable or disable generation of additional code to track speculative
+execution through conditional branches. The tracking state can then
+be used by the compiler when expanding calls to
+@code{__builtin_speculation_safe_copy} to permit a more efficient code
+sequence to be generated.
+
@item -march=@var{name}
@opindex march
Specify the name of the target architecture and, optionally, one or
performance of the code. Permissible values for this option are:
@samp{generic}, @samp{cortex-a35}, @samp{cortex-a53}, @samp{cortex-a55},
@samp{cortex-a57}, @samp{cortex-a72}, @samp{cortex-a73}, @samp{cortex-a75},
-@samp{exynos-m1}, @samp{falkor}, @samp{qdf24xx}, @samp{saphira},
-@samp{xgene1}, @samp{vulcan}, @samp{thunderx},
+@samp{cortex-a76}, @samp{exynos-m1}, @samp{falkor}, @samp{qdf24xx},
+@samp{saphira}, @samp{phecda}, @samp{xgene1}, @samp{vulcan}, @samp{thunderx},
@samp{thunderxt88}, @samp{thunderxt88p1}, @samp{thunderxt81},
@samp{thunderxt83}, @samp{thunderx2t99}, @samp{cortex-a57.cortex-a53},
@samp{cortex-a72.cortex-a53}, @samp{cortex-a73.cortex-a35},
@samp{cortex-a73.cortex-a53}, @samp{cortex-a75.cortex-a55},
+@samp{cortex-a76.cortex-a55}
@samp{native}.
The values @samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53},
@samp{cortex-a73.cortex-a35}, @samp{cortex-a73.cortex-a53},
-@samp{cortex-a75.cortex-a55} specify that GCC should tune for a
-big.LITTLE system.
+@samp{cortex-a75.cortex-a55}, @samp{cortex-a76.cortex-a55} specify that GCC
+should tune for a big.LITTLE system.
Additionally on native AArch64 GNU/Linux systems the value
@samp{native} tunes performance to the host system. This option has no effect
@item sm4
Enable the sm3 and sm4 crypto extension. This also enables Advanced SIMD instructions.
Use of this option with architectures prior to Armv8.2-A is not supported.
+@item profile
+Enable the Statistical Profiling extension. This option is only to enable the
+extension at the assembler level and does not affect code generation.
@end table
@samp{iwmmxt} and @samp{iwmmxt2}.
Additionally, the following architectures, which lack support for the
-Thumb execution state, are recognized but support is deprecated:
-@samp{armv2}, @samp{armv2a}, @samp{armv3}, @samp{armv3m},
-@samp{armv4}, @samp{armv5} and @samp{armv5e}.
+Thumb execution state, are recognized but support is deprecated: @samp{armv4}.
Many of the architectures support extensions. These can be added by
appending @samp{+@var{extension}} to the architecture name. Extension
Architectures not mentioned do not support any extensions.
@table @samp
-@item armv5e
-@itemx armv5te
+@item armv5te
@itemx armv6
@itemx armv6j
@itemx armv6k
@samp{cortex-a9}, @samp{cortex-a12}, @samp{cortex-a15}, @samp{cortex-a17},
@samp{cortex-a32}, @samp{cortex-a35}, @samp{cortex-a53}, @samp{cortex-a55},
@samp{cortex-a57}, @samp{cortex-a72}, @samp{cortex-a73}, @samp{cortex-a75},
-@samp{cortex-r4}, @samp{cortex-r4f}, @samp{cortex-r5}, @samp{cortex-r7},
-@samp{cortex-r8}, @samp{cortex-r52},
+@samp{cortex-a76}, @samp{cortex-r4}, @samp{cortex-r4f}, @samp{cortex-r5},
+@samp{cortex-r7}, @samp{cortex-r8}, @samp{cortex-r52},
@samp{cortex-m33},
@samp{cortex-m23},
@samp{cortex-m7},
@samp{cortex-a15.cortex-a7}, @samp{cortex-a17.cortex-a7},
@samp{cortex-a57.cortex-a53}, @samp{cortex-a72.cortex-a53},
@samp{cortex-a72.cortex-a35}, @samp{cortex-a73.cortex-a53},
-@samp{cortex-a75.cortex-a55}.
+@samp{cortex-a75.cortex-a55}, @samp{cortex-a76.cortex-a55}.
@option{-mtune=generic-@var{arch}} specifies that GCC should tune the
performance for a blend of processors within architecture @var{arch}.
@item -Waddr-space-convert
@opindex Waddr-space-convert
+@opindex Wno-addr-space-convert
Warn about conversions between address spaces in the case where the
resulting address space is not contained in the incoming address space.
@item -Wmisspelled-isr
@opindex Wmisspelled-isr
+@opindex Wno-misspelled-isr
Warn if the ISR is misspelled, i.e. without __vector prefix.
Enabled by default.
@end table
Supported values are in the format @samp{v@var{X}.@var{YY}.@var{Z}},
where @var{X} is a major version, @var{YY} is the minor version, and
@var{Z} is compatibility code. Example values are @samp{v3.00.a},
-@samp{v4.00.b}, @samp{v5.00.a}, @samp{v5.00.b}, @samp{v5.00.b}, @samp{v6.00.a}.
+@samp{v4.00.b}, @samp{v5.00.a}, @samp{v5.00.b}, @samp{v6.00.a}.
@item -mxl-soft-mul
@opindex mxl-soft-mul
@item executable
normal executable (default), uses startup code @file{crt0.o}.
+@item -mpic-data-is-text-relative
+@opindex mpic-data-is-text-relative
+Assume that the displacement between the text and data segments is fixed
+at static link time. This allows data to be referenced by offset from start of
+text address instead of GOT since PC-relative addressing is not supported.
+
@item xmdstub
for use with Xilinx Microprocessor Debugger (XMD) based
software intrusive debug agent called xmdstub. This uses startup file
@samp{34kc}, @samp{34kf2_1}, @samp{34kf1_1}, @samp{34kn},
@samp{74kc}, @samp{74kf2_1}, @samp{74kf1_1}, @samp{74kf3_2},
@samp{1004kc}, @samp{1004kf2_1}, @samp{1004kf1_1},
-@samp{i6400},
+@samp{i6400}, @samp{i6500},
@samp{interaptiv},
@samp{loongson2e}, @samp{loongson2f}, @samp{loongson3a},
@samp{m4k},
@samp{m5100}, @samp{m5101},
@samp{octeon}, @samp{octeon+}, @samp{octeon2}, @samp{octeon3},
@samp{orion},
-@samp{p5600},
+@samp{p5600}, @samp{p6600},
@samp{r2000}, @samp{r3000}, @samp{r3900}, @samp{r4000}, @samp{r4400},
@samp{r4600}, @samp{r4650}, @samp{r4700}, @samp{r6000}, @samp{r8000},
@samp{rm7000}, @samp{rm9000},
not intended for ordinary use in compiling user code.
@item -minterlink-compressed
-@item -mno-interlink-compressed
+@itemx -mno-interlink-compressed
@opindex minterlink-compressed
@opindex mno-interlink-compressed
Require (do not require) that code using the standard (uncompressed) MIPS ISA
@opindex mno-xpa
Use (do not use) the MIPS eXtended Physical Address (XPA) instructions.
+@item -mcrc
+@itemx -mno-crc
+@opindex mcrc
+@opindex mno-crc
+Use (do not use) the MIPS Cyclic Redundancy Check (CRC) instructions.
+
+@item -mginv
+@itemx -mno-ginv
+@opindex mginv
+@opindex mno-ginv
+Use (do not use) the MIPS Global INValidate (GINV) instructions.
+
@item -mlong64
@opindex mlong64
Force @code{long} types to be 64 bits wide. See @option{-mlong32} for
assembler files (with a @samp{.s} suffix) when assembling them.
@item -mfix-24k
-@item -mno-fix-24k
+@itemx -mno-fix-24k
@opindex mfix-24k
@opindex mno-fix-24k
Work around the 24K E48 (lost data on stores during refill) errata.
@item -mr10k-cache-barrier=@var{setting}
@opindex mr10k-cache-barrier
Specify whether GCC should insert cache barriers to avoid the
-side-effects of speculation on R10K processors.
+side effects of speculation on R10K processors.
In common with many processors, the R10K tries to predict the outcome
of a conditional branch and speculatively executes instructions from
sections. The default value of @var{num} is 8.
@item -mgpopt=@var{option}
-@item -mgpopt
+@itemx -mgpopt
@itemx -mno-gpopt
@opindex mgpopt
@opindex mno-gpopt
The @var{regexp} is a POSIX Extended Regular Expression.
This option does not affect the behavior of the @option{-G} option, and
-and the specified sections are in addition to the standard @code{.sdata}
+the specified sections are in addition to the standard @code{.sdata}
and @code{.sbss} small-data sections that are recognized by @option{-mgpopt}.
@item -mr0rel-sec=@var{regexp}
@item -mfpu
@opindex mfpu
Use hardware FPP floating point. This is the default. (FIS floating
-point on the PDP-11/40 is not supported.)
+point on the PDP-11/40 is not supported.) Implies -m45.
@item -msoft-float
@opindex msoft-float
@item -m40
@opindex m40
-Generate code for a PDP-11/40.
+Generate code for a PDP-11/40. Implies -msoft-float -mno-split.
@item -m45
@opindex m45
@item -m10
@opindex m10
-Generate code for a PDP-11/10.
-
-@item -mbcopy-builtin
-@opindex mbcopy-builtin
-Use inline @code{movmemhi} patterns for copying memory. This is the
-default.
-
-@item -mbcopy
-@opindex mbcopy
-Do not use inline @code{movmemhi} patterns for copying memory.
+Generate code for a PDP-11/10. Implies -msoft-float -mno-split.
@item -mint16
@itemx -mno-int32
@opindex mno-float64
Use 32-bit @code{float}.
-@item -mabshi
-@opindex mabshi
-Use @code{abshi2} pattern. This is the default.
-
-@item -mno-abshi
-@opindex mno-abshi
-Do not use @code{abshi2} pattern.
-
-@item -mbranch-expensive
-@opindex mbranch-expensive
-Pretend that branches are expensive. This is for experimenting with
-code generation only.
-
-@item -mbranch-cheap
-@opindex mbranch-cheap
-Do not pretend that branches are expensive. This is the default.
+@item -msplit
+@opindex msplit
+Target has split instruction and data space. Implies -m45.
@item -munix-asm
@opindex munix-asm
-Use Unix assembler syntax. This is the default when configured for
-@samp{pdp11-*-bsd}.
+Use Unix assembler syntax.
@item -mdec-asm
@opindex mdec-asm
-Use DEC assembler syntax. This is the default when configured for any
-PDP-11 target other than @samp{pdp11-*-bsd}.
+Use DEC assembler syntax.
+
+@item -mgnu-asm
+@opindex mgnu-asm
+Use GNU assembler syntax. This is the default.
@end table
@node picoChip Options
These are listed under @xref{RS/6000 and PowerPC Options}.
-@node RISC-V Options
-@subsection RISC-V Options
-@cindex RISC-V Options
-
-These command-line options are defined for RISC-V targets:
+@node PowerPC SPE Options
+@subsection PowerPC SPE Options
+@cindex PowerPC SPE options
+These @samp{-m} options are defined for PowerPC SPE:
@table @gcctabopt
-@item -mbranch-cost=@var{n}
-@opindex mbranch-cost
-Set the cost of branches to roughly @var{n} instructions.
+@item -mmfcrf
+@itemx -mno-mfcrf
+@itemx -mpopcntb
+@itemx -mno-popcntb
+@opindex mmfcrf
+@opindex mno-mfcrf
+@opindex mpopcntb
+@opindex mno-popcntb
+You use these options to specify which instructions are available on the
+processor you are using. The default value of these options is
+determined when configuring GCC@. Specifying the
+@option{-mcpu=@var{cpu_type}} overrides the specification of these
+options. We recommend you use the @option{-mcpu=@var{cpu_type}} option
+rather than the options listed above.
-@item -mplt
-@itemx -mno-plt
-@opindex plt
-When generating PIC code, do or don't allow the use of PLTs. Ignored for
-non-PIC. The default is @option{-mplt}.
+The @option{-mmfcrf} option allows GCC to generate the move from
+condition register field instruction implemented on the POWER4
+processor and other processors that support the PowerPC V2.01
+architecture.
+The @option{-mpopcntb} option allows GCC to generate the popcount and
+double-precision FP reciprocal estimate instruction implemented on the
+POWER5 processor and other processors that support the PowerPC V2.02
+architecture.
-@item -mabi=@var{ABI-string}
-@opindex mabi
-Specify integer and floating-point calling convention. @var{ABI-string}
-contains two parts: the size of integer types and the registers used for
-floating-point types. For example @samp{-march=rv64ifd -mabi=lp64d} means that
-@samp{long} and pointers are 64-bit (implicitly defining @samp{int} to be
-32-bit), and that floating-point values up to 64 bits wide are passed in F
-registers. Contrast this with @samp{-march=rv64ifd -mabi=lp64f}, which still
-allows the compiler to generate code that uses the F and D extensions but only
-allows floating-point values up to 32 bits long to be passed in registers; or
-@samp{-march=rv64ifd -mabi=lp64}, in which no floating-point arguments will be
-passed in registers.
+@item -mcpu=@var{cpu_type}
+@opindex mcpu
+Set architecture type, register usage, and
+instruction scheduling parameters for machine type @var{cpu_type}.
+Supported values for @var{cpu_type} are @samp{8540}, @samp{8548},
+and @samp{native}.
-The default for this argument is system dependent, users who want a specific
-calling convention should specify one explicitly. The valid calling
-conventions are: @samp{ilp32}, @samp{ilp32f}, @samp{ilp32d}, @samp{lp64},
-@samp{lp64f}, and @samp{lp64d}. Some calling conventions are impossible to
-implement on some ISAs: for example, @samp{-march=rv32if -mabi=ilp32d} is
+@option{-mcpu=powerpc} specifies pure 32-bit PowerPC (either
+endian), with an appropriate, generic processor model assumed for
+scheduling purposes.
+
+Specifying @samp{native} as cpu type detects and selects the
+architecture option that corresponds to the host processor of the
+system performing the compilation.
+@option{-mcpu=native} has no effect if GCC does not recognize the
+processor.
+
+The other options specify a specific processor. Code generated under
+those options runs best on that processor, and may not run at all on
+others.
+
+The @option{-mcpu} options automatically enable or disable the
+following options:
+
+@gccoptlist{-mhard-float -mmfcrf -mmultiple @gol
+-mpopcntb -mpopcntd @gol
+-msingle-float -mdouble-float @gol
+-mfloat128}
+
+The particular options set for any particular CPU varies between
+compiler versions, depending on what setting seems to produce optimal
+code for that CPU; it doesn't necessarily reflect the actual hardware's
+capabilities. If you wish to set an individual option to a particular
+value, you may specify it after the @option{-mcpu} option, like
+@option{-mcpu=8548}.
+
+@item -mtune=@var{cpu_type}
+@opindex mtune
+Set the instruction scheduling parameters for machine type
+@var{cpu_type}, but do not set the architecture type or register usage,
+as @option{-mcpu=@var{cpu_type}} does. The same
+values for @var{cpu_type} are used for @option{-mtune} as for
+@option{-mcpu}. If both are specified, the code generated uses the
+architecture and registers set by @option{-mcpu}, but the
+scheduling parameters set by @option{-mtune}.
+
+@item -msecure-plt
+@opindex msecure-plt
+Generate code that allows @command{ld} and @command{ld.so}
+to build executables and shared
+libraries with non-executable @code{.plt} and @code{.got} sections.
+This is a PowerPC
+32-bit SYSV ABI option.
+
+@item -mbss-plt
+@opindex mbss-plt
+Generate code that uses a BSS @code{.plt} section that @command{ld.so}
+fills in, and
+requires @code{.plt} and @code{.got}
+sections that are both writable and executable.
+This is a PowerPC 32-bit SYSV ABI option.
+
+@item -misel
+@itemx -mno-isel
+@opindex misel
+@opindex mno-isel
+This switch enables or disables the generation of ISEL instructions.
+
+@item -misel=@var{yes/no}
+This switch has been deprecated. Use @option{-misel} and
+@option{-mno-isel} instead.
+
+@item -mspe
+@itemx -mno-spe
+@opindex mspe
+@opindex mno-spe
+This switch enables or disables the generation of SPE simd
+instructions.
+
+@item -mspe=@var{yes/no}
+This option has been deprecated. Use @option{-mspe} and
+@option{-mno-spe} instead.
+
+@item -mfloat128
+@itemx -mno-float128
+@opindex mfloat128
+@opindex mno-float128
+Enable/disable the @var{__float128} keyword for IEEE 128-bit floating point
+and use either software emulation for IEEE 128-bit floating point or
+hardware instructions.
+
+@item -mfloat-gprs=@var{yes/single/double/no}
+@itemx -mfloat-gprs
+@opindex mfloat-gprs
+This switch enables or disables the generation of floating-point
+operations on the general-purpose registers for architectures that
+support it.
+
+The argument @samp{yes} or @samp{single} enables the use of
+single-precision floating-point operations.
+
+The argument @samp{double} enables the use of single and
+double-precision floating-point operations.
+
+The argument @samp{no} disables floating-point operations on the
+general-purpose registers.
+
+This option is currently only available on the MPC854x.
+
+@item -mfull-toc
+@itemx -mno-fp-in-toc
+@itemx -mno-sum-in-toc
+@itemx -mminimal-toc
+@opindex mfull-toc
+@opindex mno-fp-in-toc
+@opindex mno-sum-in-toc
+@opindex mminimal-toc
+Modify generation of the TOC (Table Of Contents), which is created for
+every executable file. The @option{-mfull-toc} option is selected by
+default. In that case, GCC allocates at least one TOC entry for
+each unique non-automatic variable reference in your program. GCC
+also places floating-point constants in the TOC@. However, only
+16,384 entries are available in the TOC@.
+
+If you receive a linker error message that saying you have overflowed
+the available TOC space, you can reduce the amount of TOC space used
+with the @option{-mno-fp-in-toc} and @option{-mno-sum-in-toc} options.
+@option{-mno-fp-in-toc} prevents GCC from putting floating-point
+constants in the TOC and @option{-mno-sum-in-toc} forces GCC to
+generate code to calculate the sum of an address and a constant at
+run time instead of putting that sum into the TOC@. You may specify one
+or both of these options. Each causes GCC to produce very slightly
+slower and larger code at the expense of conserving TOC space.
+
+If you still run out of space in the TOC even when you specify both of
+these options, specify @option{-mminimal-toc} instead. This option causes
+GCC to make only one TOC entry for every file. When you specify this
+option, GCC produces code that is slower and larger but which
+uses extremely little TOC space. You may wish to use this option
+only on files that contain less frequently-executed code.
+
+@item -maix32
+@opindex maix32
+Disables the 64-bit ABI. GCC defaults to @option{-maix32}.
+
+@item -mxl-compat
+@itemx -mno-xl-compat
+@opindex mxl-compat
+@opindex mno-xl-compat
+Produce code that conforms more closely to IBM XL compiler semantics
+when using AIX-compatible ABI@. Pass floating-point arguments to
+prototyped functions beyond the register save area (RSA) on the stack
+in addition to argument FPRs. Do not assume that most significant
+double in 128-bit long double value is properly rounded when comparing
+values and converting to double. Use XL symbol names for long double
+support routines.
+
+The AIX calling convention was extended but not initially documented to
+handle an obscure K&R C case of calling a function that takes the
+address of its arguments with fewer arguments than declared. IBM XL
+compilers access floating-point arguments that do not fit in the
+RSA from the stack when a subroutine is compiled without
+optimization. Because always storing floating-point arguments on the
+stack is inefficient and rarely needed, this option is not enabled by
+default and only is necessary when calling subroutines compiled by IBM
+XL compilers without optimization.
+
+@item -malign-natural
+@itemx -malign-power
+@opindex malign-natural
+@opindex malign-power
+On AIX, 32-bit Darwin, and 64-bit PowerPC GNU/Linux, the option
+@option{-malign-natural} overrides the ABI-defined alignment of larger
+types, such as floating-point doubles, on their natural size-based boundary.
+The option @option{-malign-power} instructs GCC to follow the ABI-specified
+alignment rules. GCC defaults to the standard alignment defined in the ABI@.
+
+On 64-bit Darwin, natural alignment is the default, and @option{-malign-power}
+is not supported.
+
+@item -msoft-float
+@itemx -mhard-float
+@opindex msoft-float
+@opindex mhard-float
+Generate code that does not use (uses) the floating-point register set.
+Software floating-point emulation is provided if you use the
+@option{-msoft-float} option, and pass the option to GCC when linking.
+
+@item -msingle-float
+@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}.
+
+@item -mmultiple
+@itemx -mno-multiple
+@opindex mmultiple
+@opindex mno-multiple
+Generate code that uses (does not use) the load multiple word
+instructions and the store multiple word instructions. These
+instructions are generated by default on POWER systems, and not
+generated on PowerPC systems. Do not use @option{-mmultiple} on little-endian
+PowerPC systems, since those instructions do not work when the
+processor is in little-endian mode. The exceptions are PPC740 and
+PPC750 which permit these instructions in little-endian mode.
+
+@item -mupdate
+@itemx -mno-update
+@opindex mupdate
+@opindex mno-update
+Generate code that uses (does not use) the load or store instructions
+that update the base register to the address of the calculated memory
+location. These instructions are generated by default. If you use
+@option{-mno-update}, there is a small window between the time that the
+stack pointer is updated and the address of the previous frame is
+stored, which means code that walks the stack frame across interrupts or
+signals may get corrupted data.
+
+@item -mavoid-indexed-addresses
+@itemx -mno-avoid-indexed-addresses
+@opindex mavoid-indexed-addresses
+@opindex mno-avoid-indexed-addresses
+Generate code that tries to avoid (not avoid) the use of indexed load
+or store instructions. These instructions can incur a performance
+penalty on Power6 processors in certain situations, such as when
+stepping through large arrays that cross a 16M boundary. This option
+is enabled by default when targeting Power6 and disabled otherwise.
+
+@item -mfused-madd
+@itemx -mno-fused-madd
+@opindex mfused-madd
+@opindex mno-fused-madd
+Generate code that uses (does not use) the floating-point multiply and
+accumulate instructions. These instructions are generated by default
+if hardware floating point is used. The machine-dependent
+@option{-mfused-madd} option is now mapped to the machine-independent
+@option{-ffp-contract=fast} option, and @option{-mno-fused-madd} is
+mapped to @option{-ffp-contract=off}.
+
+@item -mno-strict-align
+@itemx -mstrict-align
+@opindex mno-strict-align
+@opindex mstrict-align
+On System V.4 and embedded PowerPC systems do not (do) assume that
+unaligned memory references are handled by the system.
+
+@item -mrelocatable
+@itemx -mno-relocatable
+@opindex mrelocatable
+@opindex mno-relocatable
+Generate code that allows (does not allow) a static executable to be
+relocated to a different address at run time. A simple embedded
+PowerPC system loader should relocate the entire contents of
+@code{.got2} and 4-byte locations listed in the @code{.fixup} section,
+a table of 32-bit addresses generated by this option. For this to
+work, all objects linked together must be compiled with
+@option{-mrelocatable} or @option{-mrelocatable-lib}.
+@option{-mrelocatable} code aligns the stack to an 8-byte boundary.
+
+@item -mrelocatable-lib
+@itemx -mno-relocatable-lib
+@opindex mrelocatable-lib
+@opindex mno-relocatable-lib
+Like @option{-mrelocatable}, @option{-mrelocatable-lib} generates a
+@code{.fixup} section to allow static executables to be relocated at
+run time, but @option{-mrelocatable-lib} does not use the smaller stack
+alignment of @option{-mrelocatable}. Objects compiled with
+@option{-mrelocatable-lib} may be linked with objects compiled with
+any combination of the @option{-mrelocatable} options.
+
+@item -mno-toc
+@itemx -mtoc
+@opindex mno-toc
+@opindex mtoc
+On System V.4 and embedded PowerPC systems do not (do) assume that
+register 2 contains a pointer to a global area pointing to the addresses
+used in the program.
+
+@item -mlittle
+@itemx -mlittle-endian
+@opindex mlittle
+@opindex mlittle-endian
+On System V.4 and embedded PowerPC systems compile code for the
+processor in little-endian mode. The @option{-mlittle-endian} option is
+the same as @option{-mlittle}.
+
+@item -mbig
+@itemx -mbig-endian
+@opindex mbig
+@opindex mbig-endian
+On System V.4 and embedded PowerPC systems compile code for the
+processor in big-endian mode. The @option{-mbig-endian} option is
+the same as @option{-mbig}.
+
+@item -mdynamic-no-pic
+@opindex mdynamic-no-pic
+On Darwin and Mac OS X systems, compile code so that it is not
+relocatable, but that its external references are relocatable. The
+resulting code is suitable for applications, but not shared
+libraries.
+
+@item -msingle-pic-base
+@opindex msingle-pic-base
+Treat the register used for PIC addressing as read-only, rather than
+loading it in the prologue for each function. The runtime system is
+responsible for initializing this register with an appropriate value
+before execution begins.
+
+@item -mprioritize-restricted-insns=@var{priority}
+@opindex mprioritize-restricted-insns
+This option controls the priority that is assigned to
+dispatch-slot restricted instructions during the second scheduling
+pass. The argument @var{priority} takes the value @samp{0}, @samp{1},
+or @samp{2} to assign no, highest, or second-highest (respectively)
+priority to dispatch-slot restricted
+instructions.
+
+@item -msched-costly-dep=@var{dependence_type}
+@opindex msched-costly-dep
+This option controls which dependences are considered costly
+by the target during instruction scheduling. The argument
+@var{dependence_type} takes one of the following values:
+
+@table @asis
+@item @samp{no}
+No dependence is costly.
+
+@item @samp{all}
+All dependences are costly.
+
+@item @samp{true_store_to_load}
+A true dependence from store to load is costly.
+
+@item @samp{store_to_load}
+Any dependence from store to load is costly.
+
+@item @var{number}
+Any dependence for which the latency is greater than or equal to
+@var{number} is costly.
+@end table
+
+@item -minsert-sched-nops=@var{scheme}
+@opindex minsert-sched-nops
+This option controls which NOP insertion scheme is used during
+the second scheduling pass. The argument @var{scheme} takes one of the
+following values:
+
+@table @asis
+@item @samp{no}
+Don't insert NOPs.
+
+@item @samp{pad}
+Pad with NOPs any dispatch group that has vacant issue slots,
+according to the scheduler's grouping.
+
+@item @samp{regroup_exact}
+Insert NOPs to force costly dependent insns into
+separate groups. Insert exactly as many NOPs as needed to force an insn
+to a new group, according to the estimated processor grouping.
+
+@item @var{number}
+Insert NOPs to force costly dependent insns into
+separate groups. Insert @var{number} NOPs to force an insn to a new group.
+@end table
+
+@item -mcall-sysv
+@opindex mcall-sysv
+On System V.4 and embedded PowerPC systems compile code using calling
+conventions that adhere to the March 1995 draft of the System V
+Application Binary Interface, PowerPC processor supplement. This is the
+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-aixdesc
+@opindex m
+On System V.4 and embedded PowerPC systems compile code for the AIX
+operating system.
+
+@item -mcall-linux
+@opindex mcall-linux
+On System V.4 and embedded PowerPC systems compile code for the
+Linux-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)@.
+
+@item -msvr4-struct-return
+@opindex msvr4-struct-return
+Return structures smaller than 8 bytes in registers (as specified by the
+SVR4 ABI)@.
+
+@item -mabi=@var{abi-type}
+@opindex mabi
+Extend the current ABI with a particular extension, or remove such extension.
+Valid values are @samp{altivec}, @samp{no-altivec}, @samp{spe},
+@samp{no-spe}, @samp{ibmlongdouble}, @samp{ieeelongdouble},
+@samp{elfv1}, @samp{elfv2}@.
+
+@item -mabi=spe
+@opindex mabi=spe
+Extend the current ABI with SPE ABI extensions. This does not change
+the default ABI, instead it adds the SPE ABI extensions to the current
+ABI@.
+
+@item -mabi=no-spe
+@opindex mabi=no-spe
+Disable Book-E SPE ABI extensions for the current ABI@.
+
+@item -mabi=ibmlongdouble
+@opindex mabi=ibmlongdouble
+Change the current ABI to use IBM extended-precision long double.
+This is not likely to work if your system defaults to using IEEE
+extended-precision long double. If you change the long double type
+from IEEE extended-precision, the compiler will issue a warning unless
+you use the @option{-Wno-psabi} option.
+
+@item -mabi=ieeelongdouble
+@opindex mabi=ieeelongdouble
+Change the current ABI to use IEEE extended-precision long double.
+This is not likely to work if your system defaults to using IBM
+extended-precision long double. If you change the long double type
+from IBM extended-precision, the compiler will issue a warning unless
+you use the @option{-Wno-psabi} option.
+
+@item -mabi=elfv1
+@opindex mabi=elfv1
+Change the current ABI to use the ELFv1 ABI.
+This is the default ABI for big-endian PowerPC 64-bit Linux.
+Overriding the default ABI requires special system support and is
+likely to fail in spectacular ways.
+
+@item -mabi=elfv2
+@opindex mabi=elfv2
+Change the current ABI to use the ELFv2 ABI.
+This is the default ABI for little-endian PowerPC 64-bit Linux.
+Overriding the default ABI requires special system support and is
+likely to fail in spectacular ways.
+
+@item -mgnu-attribute
+@itemx -mno-gnu-attribute
+@opindex mgnu-attribute
+@opindex mno-gnu-attribute
+Emit .gnu_attribute assembly directives to set tag/value pairs in a
+.gnu.attributes section that specify ABI variations in function
+parameters or return values.
+
+@item -mprototype
+@itemx -mno-prototype
+@opindex mprototype
+@opindex mno-prototype
+On System V.4 and embedded PowerPC systems assume that all calls to
+variable argument functions are properly prototyped. Otherwise, the
+compiler must insert an instruction before every non-prototyped call to
+set or clear bit 6 of the condition code register (@code{CR}) to
+indicate whether floating-point values are passed in the floating-point
+registers in case the function takes variable arguments. With
+@option{-mprototype}, only calls to prototyped variable argument functions
+set or clear the bit.
+
+@item -msim
+@opindex msim
+On embedded PowerPC systems, assume that the startup module is called
+@file{sim-crt0.o} and that the standard C libraries are @file{libsim.a} and
+@file{libc.a}. This is the default for @samp{powerpc-*-eabisim}
+configurations.
+
+@item -mmvme
+@opindex mmvme
+On embedded PowerPC systems, assume that the startup module is called
+@file{crt0.o} and the standard C libraries are @file{libmvme.a} and
+@file{libc.a}.
+
+@item -mads
+@opindex mads
+On embedded PowerPC systems, assume that the startup module is called
+@file{crt0.o} and the standard C libraries are @file{libads.a} and
+@file{libc.a}.
+
+@item -myellowknife
+@opindex myellowknife
+On embedded PowerPC systems, assume that the startup module is called
+@file{crt0.o} and the standard C libraries are @file{libyk.a} and
+@file{libc.a}.
+
+@item -mvxworks
+@opindex mvxworks
+On System V.4 and embedded PowerPC systems, specify that you are
+compiling for a VxWorks system.
+
+@item -memb
+@opindex memb
+On embedded PowerPC systems, set the @code{PPC_EMB} bit in the ELF flags
+header to indicate that @samp{eabi} extended relocations are used.
+
+@item -meabi
+@itemx -mno-eabi
+@opindex meabi
+@opindex mno-eabi
+On System V.4 and embedded PowerPC systems do (do not) adhere to the
+Embedded Applications Binary Interface (EABI), which is a set of
+modifications to the System V.4 specifications. Selecting @option{-meabi}
+means that the stack is aligned to an 8-byte boundary, a function
+@code{__eabi} is called from @code{main} to set up the EABI
+environment, and the @option{-msdata} option can use both @code{r2} and
+@code{r13} to point to two separate small data areas. Selecting
+@option{-mno-eabi} means that the stack is aligned to a 16-byte boundary,
+no EABI initialization function is called from @code{main}, and the
+@option{-msdata} option only uses @code{r13} to point to a single
+small data area. The @option{-meabi} option is on by default if you
+configured GCC using one of the @samp{powerpc*-*-eabi*} options.
+
+@item -msdata=eabi
+@opindex msdata=eabi
+On System V.4 and embedded PowerPC systems, put small initialized
+@code{const} global and static data in the @code{.sdata2} section, which
+is pointed to by register @code{r2}. Put small initialized
+non-@code{const} global and static data in the @code{.sdata} section,
+which is pointed to by register @code{r13}. Put small uninitialized
+global and static data in the @code{.sbss} section, which is adjacent to
+the @code{.sdata} section. The @option{-msdata=eabi} option is
+incompatible with the @option{-mrelocatable} option. The
+@option{-msdata=eabi} option also sets the @option{-memb} option.
+
+@item -msdata=sysv
+@opindex msdata=sysv
+On System V.4 and embedded PowerPC systems, put small global and static
+data in the @code{.sdata} section, which is pointed to by register
+@code{r13}. Put small uninitialized global and static data in the
+@code{.sbss} section, which is adjacent to the @code{.sdata} section.
+The @option{-msdata=sysv} option is incompatible with the
+@option{-mrelocatable} option.
+
+@item -msdata=default
+@itemx -msdata
+@opindex msdata=default
+@opindex msdata
+On System V.4 and embedded PowerPC systems, if @option{-meabi} is used,
+compile code the same as @option{-msdata=eabi}, otherwise compile code the
+same as @option{-msdata=sysv}.
+
+@item -msdata=data
+@opindex msdata=data
+On System V.4 and embedded PowerPC systems, put small global
+data in the @code{.sdata} section. Put small uninitialized global
+data in the @code{.sbss} section. Do not use register @code{r13}
+to address small data however. This is the default behavior unless
+other @option{-msdata} options are used.
+
+@item -msdata=none
+@itemx -mno-sdata
+@opindex msdata=none
+@opindex mno-sdata
+On embedded PowerPC systems, put all initialized global and static data
+in the @code{.data} section, and all uninitialized data in the
+@code{.bss} section.
+
+@item -mblock-move-inline-limit=@var{num}
+@opindex mblock-move-inline-limit
+Inline all block moves (such as calls to @code{memcpy} or structure
+copies) less than or equal to @var{num} bytes. The minimum value for
+@var{num} is 32 bytes on 32-bit targets and 64 bytes on 64-bit
+targets. The default value is target-specific.
+
+@item -G @var{num}
+@opindex G
+@cindex smaller data references (PowerPC)
+@cindex .sdata/.sdata2 references (PowerPC)
+On embedded PowerPC systems, put global and static items less than or
+equal to @var{num} bytes into the small data or BSS sections instead of
+the normal data or BSS section. By default, @var{num} is 8. The
+@option{-G @var{num}} switch is also passed to the linker.
+All modules should be compiled with the same @option{-G @var{num}} value.
+
+@item -mregnames
+@itemx -mno-regnames
+@opindex mregnames
+@opindex mno-regnames
+On System V.4 and embedded PowerPC systems do (do not) emit register
+names in the assembly language output using symbolic forms.
+
+@item -mlongcall
+@itemx -mno-longcall
+@opindex mlongcall
+@opindex mno-longcall
+By default assume that all calls are far away so that a longer and more
+expensive calling sequence is required. This is required for calls
+farther than 32 megabytes (33,554,432 bytes) from the current location.
+A short call is generated if the compiler knows
+the call cannot be that far away. This setting can be overridden by
+the @code{shortcall} function attribute, or by @code{#pragma
+longcall(0)}.
+
+Some linkers are capable of detecting out-of-range calls and generating
+glue code on the fly. On these systems, long calls are unnecessary and
+generate slower code. As of this writing, the AIX linker can do this,
+as can the GNU linker for PowerPC/64. It is planned to add this feature
+to the GNU linker for 32-bit PowerPC systems as well.
+
+In the future, GCC may ignore all longcall specifications
+when the linker is known to generate glue.
+
+@item -mtls-markers
+@itemx -mno-tls-markers
+@opindex mtls-markers
+@opindex mno-tls-markers
+Mark (do not mark) calls to @code{__tls_get_addr} with a relocation
+specifying the function argument. The relocation allows the linker to
+reliably associate function call with argument setup instructions for
+TLS optimization, which in turn allows GCC to better schedule the
+sequence.
+
+@item -mrecip
+@itemx -mno-recip
+@opindex mrecip
+This option enables use of the reciprocal estimate and
+reciprocal square root estimate instructions with additional
+Newton-Raphson steps to increase precision instead of doing a divide or
+square root and divide for floating-point arguments. You should use
+the @option{-ffast-math} option when using @option{-mrecip} (or at
+least @option{-funsafe-math-optimizations},
+@option{-ffinite-math-only}, @option{-freciprocal-math} and
+@option{-fno-trapping-math}). Note that while the throughput of the
+sequence is generally higher than the throughput of the non-reciprocal
+instruction, the precision of the sequence can be decreased by up to 2
+ulp (i.e.@: the inverse of 1.0 equals 0.99999994) for reciprocal square
+roots.
+
+@item -mrecip=@var{opt}
+@opindex mrecip=opt
+This option controls which reciprocal estimate instructions
+may be used. @var{opt} is a comma-separated list of options, which may
+be preceded by a @code{!} to invert the option:
+
+@table @samp
+
+@item all
+Enable all estimate instructions.
+
+@item default
+Enable the default instructions, equivalent to @option{-mrecip}.
+
+@item none
+Disable all estimate instructions, equivalent to @option{-mno-recip}.
+
+@item div
+Enable the reciprocal approximation instructions for both
+single and double precision.
+
+@item divf
+Enable the single-precision reciprocal approximation instructions.
+
+@item divd
+Enable the double-precision reciprocal approximation instructions.
+
+@item rsqrt
+Enable the reciprocal square root approximation instructions for both
+single and double precision.
+
+@item rsqrtf
+Enable the single-precision reciprocal square root approximation instructions.
+
+@item rsqrtd
+Enable the double-precision reciprocal square root approximation instructions.
+
+@end table
+
+So, for example, @option{-mrecip=all,!rsqrtd} enables
+all of the reciprocal estimate instructions, except for the
+@code{FRSQRTE}, @code{XSRSQRTEDP}, and @code{XVRSQRTEDP} instructions
+which handle the double-precision reciprocal square root calculations.
+
+@item -mrecip-precision
+@itemx -mno-recip-precision
+@opindex mrecip-precision
+Assume (do not assume) that the reciprocal estimate instructions
+provide higher-precision estimates than is mandated by the PowerPC
+ABI. Selecting @option{-mcpu=power6}, @option{-mcpu=power7} or
+@option{-mcpu=power8} automatically selects @option{-mrecip-precision}.
+The double-precision square root estimate instructions are not generated by
+default on low-precision machines, since they do not provide an
+estimate that converges after three steps.
+
+@item -mpointers-to-nested-functions
+@itemx -mno-pointers-to-nested-functions
+@opindex mpointers-to-nested-functions
+Generate (do not generate) code to load up the static chain register
+(@code{r11}) when calling through a pointer on AIX and 64-bit Linux
+systems where a function pointer points to a 3-word descriptor giving
+the function address, TOC value to be loaded in register @code{r2}, and
+static chain value to be loaded in register @code{r11}. The
+@option{-mpointers-to-nested-functions} is on by default. You cannot
+call through pointers to nested functions or pointers
+to functions compiled in other languages that use the static chain if
+you use @option{-mno-pointers-to-nested-functions}.
+
+@item -msave-toc-indirect
+@itemx -mno-save-toc-indirect
+@opindex msave-toc-indirect
+Generate (do not generate) code to save the TOC value in the reserved
+stack location in the function prologue if the function calls through
+a pointer on AIX and 64-bit Linux systems. If the TOC value is not
+saved in the prologue, it is saved just before the call through the
+pointer. The @option{-mno-save-toc-indirect} option is the default.
+
+@item -mcompat-align-parm
+@itemx -mno-compat-align-parm
+@opindex mcompat-align-parm
+Generate (do not generate) code to pass structure parameters with a
+maximum alignment of 64 bits, for compatibility with older versions
+of GCC.
+
+Older versions of GCC (prior to 4.9.0) incorrectly did not align a
+structure parameter on a 128-bit boundary when that structure contained
+a member requiring 128-bit alignment. This is corrected in more
+recent versions of GCC. This option may be used to generate code
+that is compatible with functions compiled with older versions of
+GCC.
+
+The @option{-mno-compat-align-parm} option is the default.
+
+@item -mstack-protector-guard=@var{guard}
+@itemx -mstack-protector-guard-reg=@var{reg}
+@itemx -mstack-protector-guard-offset=@var{offset}
+@itemx -mstack-protector-guard-symbol=@var{symbol}
+@opindex mstack-protector-guard
+@opindex mstack-protector-guard-reg
+@opindex mstack-protector-guard-offset
+@opindex mstack-protector-guard-symbol
+Generate stack protection code using canary at @var{guard}. Supported
+locations are @samp{global} for global canary or @samp{tls} for per-thread
+canary in the TLS block (the default with GNU libc version 2.4 or later).
+
+With the latter choice the options
+@option{-mstack-protector-guard-reg=@var{reg}} and
+@option{-mstack-protector-guard-offset=@var{offset}} furthermore specify
+which register to use as base register for reading the canary, and from what
+offset from that base register. The default for those is as specified in the
+relevant ABI. @option{-mstack-protector-guard-symbol=@var{symbol}} overrides
+the offset with a symbol reference to a canary in the TLS block.
+@end table
+
+
+@node RISC-V Options
+@subsection RISC-V Options
+@cindex RISC-V Options
+
+These command-line options are defined for RISC-V targets:
+
+@table @gcctabopt
+@item -mbranch-cost=@var{n}
+@opindex mbranch-cost
+Set the cost of branches to roughly @var{n} instructions.
+
+@item -mplt
+@itemx -mno-plt
+@opindex plt
+When generating PIC code, do or don't allow the use of PLTs. Ignored for
+non-PIC. The default is @option{-mplt}.
+
+@item -mabi=@var{ABI-string}
+@opindex mabi
+Specify integer and floating-point calling convention. @var{ABI-string}
+contains two parts: the size of integer types and the registers used for
+floating-point types. For example @samp{-march=rv64ifd -mabi=lp64d} means that
+@samp{long} and pointers are 64-bit (implicitly defining @samp{int} to be
+32-bit), and that floating-point values up to 64 bits wide are passed in F
+registers. Contrast this with @samp{-march=rv64ifd -mabi=lp64f}, which still
+allows the compiler to generate code that uses the F and D extensions but only
+allows floating-point values up to 32 bits long to be passed in registers; or
+@samp{-march=rv64ifd -mabi=lp64}, in which no floating-point arguments will be
+passed in registers.
+
+The default for this argument is system dependent, users who want a specific
+calling convention should specify one explicitly. The valid calling
+conventions are: @samp{ilp32}, @samp{ilp32f}, @samp{ilp32d}, @samp{lp64},
+@samp{lp64f}, and @samp{lp64d}. Some calling conventions are impossible to
+implement on some ISAs: for example, @samp{-march=rv32if -mabi=ilp32d} is
invalid because the ABI requires 64-bit values be passed in F registers, but F
-registers are only 32 bits wide.
+registers are only 32 bits wide. There is also the @samp{ilp32e} ABI that can
+only be used with the @samp{rv32e} architecture. This ABI is not well
+specified at present, and is subject to change.
@item -mfdiv
@itemx -mno-fdiv
@item -march=@var{ISA-string}
@opindex march
Generate code for given RISC-V ISA (e.g.@ @samp{rv64im}). ISA strings must be
-lower-case. Examples include @samp{rv64i}, @samp{rv32g}, and @samp{rv32imaf}.
+lower-case. Examples include @samp{rv64i}, @samp{rv32g}, @samp{rv32e}, and
+@samp{rv32imaf}.
@item -mtune=@var{processor-string}
@opindex mtune
addresses. The alternative is to use assembler macros instead, which may
limit optimization.
+@item -mrelax
+@itemx -mno-relax
+Take advantage of linker relaxations to reduce the number of instructions
+required to materialize symbol addresses. The default is to take advantage of
+linker relaxations.
+
@end table
@node RL78 Options
@option{-m32bit-doubles}.
@item -msave-mduc-in-interrupts
-@item -mno-save-mduc-in-interrupts
+@itemx -mno-save-mduc-in-interrupts
@opindex msave-mduc-in-interrupts
@opindex mno-save-mduc-in-interrupts
Specifies that interrupt handler functions should preserve the
@gccoptlist{-maltivec -mfprnd -mhard-float -mmfcrf -mmultiple @gol
-mpopcntb -mpopcntd -mpowerpc64 @gol
--mpowerpc-gpopt -mpowerpc-gfxopt -msingle-float -mdouble-float @gol
--msimple-fpu -mmulhw -mdlmzb -mmfpgpr -mvsx @gol
--mcrypto -mdirect-move -mhtm -mpower8-fusion -mpower8-vector @gol
+-mpowerpc-gpopt -mpowerpc-gfxopt @gol
+-mmulhw -mdlmzb -mmfpgpr -mvsx @gol
+-mcrypto -mhtm -mpower8-fusion -mpower8-vector @gol
-mquad-memory -mquad-memory-atomic -mfloat128 -mfloat128-hardware}
The particular options set for any particular CPU varies between
@opindex maltivec=be
Generate AltiVec instructions using big-endian element order,
regardless of whether the target is big- or little-endian. This is
-the default when targeting a big-endian platform.
+the default when targeting a big-endian platform. Using this option
+is currently deprecated. Support for this feature will be removed in
+GCC 9.
The element order is used to interpret element numbers in AltiVec
intrinsics such as @code{vec_splat}, @code{vec_extract}, and
This switch has been deprecated. Use @option{-misel} and
@option{-mno-isel} instead.
-@item -mspe
-@itemx -mno-spe
-@opindex mspe
-@opindex mno-spe
-This switch enables or disables the generation of SPE simd
-instructions.
-
-@item -mpaired
-@itemx -mno-paired
-@opindex mpaired
-@opindex mno-paired
-This switch enables or disables the generation of PAIRED simd
-instructions.
-
-@item -mspe=@var{yes/no}
-This option has been deprecated. Use @option{-mspe} and
-@option{-mno-spe} instead.
-
@item -mvsx
@itemx -mno-vsx
@opindex mvsx
access to the cryptographic instructions that were added in version
2.07 of the PowerPC ISA.
-@item -mdirect-move
-@itemx -mno-direct-move
-@opindex mdirect-move
-@opindex mno-direct-move
-Generate code that uses (does not use) the instructions to move data
-between the general purpose registers and the vector/scalar (VSX)
-registers that were added in version 2.07 of the PowerPC ISA.
-
@item -mhtm
@itemx -mno-htm
@opindex mhtm
Linux systems using the ISA 3.0 instruction set, and disabled on other
systems.
-@item -mfloat-gprs=@var{yes/single/double/no}
-@itemx -mfloat-gprs
-@opindex mfloat-gprs
-This switch enables or disables the generation of floating-point
-operations on the general-purpose registers for architectures that
-support it.
-
-The argument @samp{yes} or @samp{single} enables the use of
-single-precision floating-point operations.
-
-The argument @samp{double} enables the use of single and
-double-precision floating-point operations.
-
-The argument @samp{no} disables floating-point operations on the
-general-purpose registers.
-
-This option is currently only available on the MPC854x.
-
@item -m32
@itemx -m64
@opindex m32
Software floating-point emulation is provided if you use the
@option{-msoft-float} option, and pass the option to GCC when linking.
-@item -msingle-float
-@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}.
-
-@item -msimple-fpu
-@opindex msimple-fpu
-Do not generate @code{sqrt} and @code{div} instructions for hardware
-floating-point unit.
-
-@item -mfpu=@var{name}
-@opindex mfpu
-Specify type of floating-point unit. Valid values for @var{name} are
-@samp{sp_lite} (equivalent to @option{-msingle-float -msimple-fpu}),
-@samp{dp_lite} (equivalent to @option{-mdouble-float -msimple-fpu}),
-@samp{sp_full} (equivalent to @option{-msingle-float}),
-and @samp{dp_full} (equivalent to @option{-mdouble-float}).
-
-@item -mxilinx-fpu
-@opindex mxilinx-fpu
-Perform optimizations for the floating-point unit on Xilinx PPC 405/440.
-
@item -mmultiple
@itemx -mno-multiple
@opindex mmultiple
On System V.4 and embedded PowerPC systems compile code for the
OpenBSD operating system.
+@item -mtraceback=@var{traceback_type}
+@opindex mtraceback
+Select the type of traceback table. Valid values for @var{traceback_type}
+are @samp{full}, @samp{part}, and @samp{no}.
+
@item -maix-struct-return
@opindex maix-struct-return
Return all structures in memory (as specified by the AIX ABI)@.
@item -mabi=@var{abi-type}
@opindex mabi
Extend the current ABI with a particular extension, or remove such extension.
-Valid values are @samp{altivec}, @samp{no-altivec}, @samp{spe},
-@samp{no-spe}, @samp{ibmlongdouble}, @samp{ieeelongdouble},
+Valid values are @samp{altivec}, @samp{no-altivec},
+@samp{ibmlongdouble}, @samp{ieeelongdouble},
@samp{elfv1}, @samp{elfv2}@.
-@item -mabi=spe
-@opindex mabi=spe
-Extend the current ABI with SPE ABI extensions. This does not change
-the default ABI, instead it adds the SPE ABI extensions to the current
-ABI@.
-
-@item -mabi=no-spe
-@opindex mabi=no-spe
-Disable Book-E SPE ABI extensions for the current ABI@.
-
@item -mabi=ibmlongdouble
@opindex mabi=ibmlongdouble
Change the current ABI to use IBM extended-precision long double.
in the @code{.data} section, and all uninitialized data in the
@code{.bss} section.
+@item -mreadonly-in-sdata
+@opindex mreadonly-in-sdata
+@opindex mno-readonly-in-sdata
+Put read-only objects in the @code{.sdata} section as well. This is the
+default.
+
@item -mblock-move-inline-limit=@var{num}
@opindex mblock-move-inline-limit
Inline all block moves (such as calls to @code{memcpy} or structure
@var{num} is 32 bytes on 32-bit targets and 64 bytes on 64-bit
targets. The default value is target-specific.
+@item -mblock-compare-inline-limit=@var{num}
+@opindex mblock-compare-inline-limit
+Generate non-looping inline code for all block compares (such as calls
+to @code{memcmp} or structure compares) less than or equal to @var{num}
+bytes. If @var{num} is 0, all inline expansion (non-loop and loop) of
+block compare is disabled. The default value is target-specific.
+
+@item -mblock-compare-inline-loop-limit=@var{num}
+@opindex mblock-compare-inline-loop-limit
+Generate an inline expansion using loop code for all block compares that
+are less than or equal to @var{num} bytes, but greater than the limit
+for non-loop inline block compare expansion. If the block length is not
+constant, at most @var{num} bytes will be compared before @code{memcmp}
+is called to compare the remainder of the block. The default value is
+target-specific.
+
+@item -mstring-compare-inline-limit=@var{num}
+@opindex mstring-compare-inline-limit
+Generate at most @var{num} pairs of load instructions to compare the
+string inline. If the difference or end of string is not found at the
+end of the inline compare a call to @code{strcmp} or @code{strncmp} will
+take care of the rest of the comparison. The default is 8 pairs of
+loads, which will compare 64 bytes on a 64-bit target and 32 bytes on a
+32-bit target.
+
@item -G @var{num}
@opindex G
@cindex smaller data references (PowerPC)
@samp{z196}/@samp{arch9}, @samp{zEC12}, @samp{z13}/@samp{arch11}, and
@samp{native}.
-The default is @option{-march=z900}. @samp{g5}/@samp{arch3} and
-@samp{g6} are deprecated and will be removed with future releases.
+The default is @option{-march=z900}.
Specifying @samp{native} as cpu type can be used to select the best
architecture option for the host processor.
produces code optimized for the local machine under the constraints
of the selected instruction set.
+@item x86-64
+A generic CPU with 64-bit extensions.
+
@item i386
Original Intel i386 CPU@.
Intel Silvermont CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
SSE4.1, SSE4.2, POPCNT, AES, PCLMUL and RDRND instruction set support.
+@item goldmont
+Intel Goldmont CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, AES, PCLMUL, RDRND, XSAVE, XSAVEOPT and FSGSBASE
+instruction set support.
+
+@item goldmont-plus
+Intel Goldmont Plus CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
+SSSE3, SSE4.1, SSE4.2, POPCNT, AES, PCLMUL, RDRND, XSAVE, XSAVEOPT, FSGSBASE,
+PTWRITE, RDPID, SGX and UMIP instruction set support.
+
+@item tremont
+Intel Tremont CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3, SSSE3,
+SSE4.1, SSE4.2, POPCNT, AES, PCLMUL, RDRND, XSAVE, XSAVEOPT, FSGSBASE, PTWRITE,
+RDPID, SGX, UMIP, GFNI-SSE, CLWB and ENCLV instruction set support.
+
@item knl
Intel Knight's Landing CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
SSSE3, SSE4.1, SSE4.2, POPCNT, AVX, AVX2, AES, PCLMUL, FSGSBASE, RDRND, FMA,
Intel Skylake Server CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2, SSE3,
SSSE3, SSE4.1, SSE4.2, POPCNT, PKU, AVX, AVX2, AES, PCLMUL, FSGSBASE, RDRND, FMA,
BMI, BMI2, F16C, RDSEED, ADCX, PREFETCHW, CLFLUSHOPT, XSAVEC, XSAVES, AVX512F,
-AVX512VL, AVX512BW, AVX512DQ and AVX512CD instruction set support.
+CLWB, AVX512VL, AVX512BW, AVX512DQ and AVX512CD instruction set support.
@item cannonlake
Intel Cannonlake Server CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2,
SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, PKU, AVX, AVX2, AES, PCLMUL, FSGSBASE,
RDRND, FMA, BMI, BMI2, F16C, RDSEED, ADCX, PREFETCHW, CLFLUSHOPT, XSAVEC,
XSAVES, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD, AVX512VBMI,
-AVX512IFMA, SHA, CLWB and UMIP instruction set support.
+AVX512IFMA, SHA and UMIP instruction set support.
-@item Icelake
-Intel Icelake Server CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2,
+@item icelake-client
+Intel Icelake Client CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2,
SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, PKU, AVX, AVX2, AES, PCLMUL, FSGSBASE,
RDRND, FMA, BMI, BMI2, F16C, RDSEED, ADCX, PREFETCHW, CLFLUSHOPT, XSAVEC,
XSAVES, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD, AVX512VBMI,
AVX512IFMA, SHA, CLWB, UMIP, RDPID, GFNI, AVX512VBMI2, AVX512VPOPCNTDQ,
AVX512BITALG, AVX512VNNI, VPCLMULQDQ, VAES instruction set support.
+@item icelake-server
+Intel Icelake Server CPU with 64-bit extensions, MOVBE, MMX, SSE, SSE2,
+SSE3, SSSE3, SSE4.1, SSE4.2, POPCNT, PKU, AVX, AVX2, AES, PCLMUL, FSGSBASE,
+RDRND, FMA, BMI, BMI2, F16C, RDSEED, ADCX, PREFETCHW, CLFLUSHOPT, XSAVEC,
+XSAVES, AVX512F, AVX512VL, AVX512BW, AVX512DQ, AVX512CD, AVX512VBMI,
+AVX512IFMA, SHA, CLWB, UMIP, RDPID, GFNI, AVX512VBMI2, AVX512VPOPCNTDQ,
+AVX512BITALG, AVX512VNNI, VPCLMULQDQ, VAES, PCONFIG and WBNOINVD instruction
+set support.
+
@item k6
AMD K6 CPU with MMX instruction set support.
comparison is unordered.
@item -m80387
-@item -mhard-float
+@itemx -mhard-float
@opindex 80387
@opindex mhard-float
Generate output containing 80387 instructions for floating point.
@item -mno-80387
-@item -msoft-float
+@itemx -msoft-float
@opindex no-80387
@opindex msoft-float
Generate output containing library calls for floating point.
@opindex mno-fancy-math-387
Some 387 emulators do not support the @code{sin}, @code{cos} and
@code{sqrt} instructions for the 387. Specify this option to avoid
-generating those instructions. This option is the default on
-OpenBSD and NetBSD@. This option is overridden when @option{-march}
+generating those instructions.
+This option is overridden when @option{-march}
indicates that the target CPU always has an FPU and so the
instruction does not need emulation. These
instructions are not generated unless you also use the
@itemx -mpclmul
@opindex mpclmul
@need 200
-@itemx -mclfushopt
-@opindex mclfushopt
+@itemx -mclflushopt
+@opindex mclflushopt
@need 200
@itemx -mfsgsbase
@opindex mfsgsbase
@itemx -mfma
@opindex mfma
@need 200
+@itemx -mpconfig
+@opindex mpconfig
+@need 200
+@itemx -mwbnoinvd
+@opindex mwbnoinvd
+@need 200
@itemx -mfma4
@opindex mfma4
@need 200
@itemx -mtbm
@opindex mtbm
@need 200
-@itemx -mmpx
-@opindex mmpx
-@need 200
@itemx -mmwaitx
@opindex mmwaitx
@need 200
@itemx -mpku
@opindex mpku
@need 200
-@itemx -mcet
-@opindex mcet
-@need 200
@itemx -mavx512vbmi2
@opindex mavx512vbmi2
@need 200
@itemx -mvaes
@opindex mvaes
@need 200
+@itemx -mwaitpkg
+@opindex -mwaitpkg
+@need 200
@itemx -mvpclmulqdq
@opindex mvpclmulqdq
@need 200
@itemx -mavx512bitalg
@opindex mavx512bitalg
@need 200
+@itemx -mmovdiri
+@opindex mmovdiri
+@need 200
+@itemx -mmovdir64b
+@opindex mmovdir64b
+@need 200
@itemx -mavx512vpopcntdq
@opindex mavx512vpopcntdq
+@need 200
+@itemx -mcldemote
+@opindex mcldemote
These switches enable the use of instructions in the MMX, SSE,
SSE2, SSE3, SSSE3, SSE4.1, AVX, AVX2, AVX512F, AVX512PF, AVX512ER, AVX512CD,
SHA, AES, PCLMUL, FSGSBASE, RDRND, F16C, FMA, SSE4A, FMA4, XOP, LWP, ABM,
-AVX512VL, AVX512BW, AVX512DQ, AVX512IFMA, AVX512VBMI, BMI, BMI2, VAES,
-FXSR, XSAVE, XSAVEOPT, LZCNT, RTM, MPX, MWAITX, PKU, IBT, SHSTK, AVX512VBMI2,
-GFNI, VPCLMULQDQ, AVX512BITALG, AVX512VPOPCNTDQ3DNow!@: or enhanced 3DNow!@:
-extended instruction sets.
-Each has a corresponding @option{-mno-} option to disable use of these
+AVX512VL, AVX512BW, AVX512DQ, AVX512IFMA, AVX512VBMI, BMI, BMI2, VAES, WAITPKG,
+FXSR, XSAVE, XSAVEOPT, LZCNT, RTM, MWAITX, PKU, IBT, SHSTK, AVX512VBMI2,
+GFNI, VPCLMULQDQ, AVX512BITALG, MOVDIRI, MOVDIR64B,
+AVX512VPOPCNTDQ, CLDEMOTE, 3DNow!@: or enhanced 3DNow!@: extended instruction
+sets. Each has a corresponding @option{-mno-} option to disable use of these
instructions.
These extensions are also available as built-in functions: see
the file containing the CPU detection code should be compiled without
these options.
-The @option{-mcet} option turns on the @option{-mibt} and @option{-mshstk}
-options. The @option{-mibt} option enables indirect branch tracking support
-and the @option{-mshstk} option enables shadow stack support from
-Intel Control-flow Enforcement Technology (CET). The compiler also provides
-a number of built-in functions for fine-grained control in a CET-based
-application. See @xref{x86 Built-in Functions}, for more information.
-
@item -mdump-tune-features
@opindex mdump-tune-features
This option instructs GCC to dump the names of the x86 performance
This option enables use of the @code{movbe} instruction to implement
@code{__builtin_bswap32} and @code{__builtin_bswap64}.
-@item -mibt
-@opindex mibt
-This option tells the compiler to use indirect branch tracking support
-(for indirect calls and jumps) from x86 Control-flow Enforcement
-Technology (CET). The option has effect only if the
-@option{-fcf-protection=full} or @option{-fcf-protection=branch} option
-is specified. The option @option{-mibt} is on by default when the
-@code{-mcet} option is specified.
-
@item -mshstk
@opindex mshstk
-This option tells the compiler to use shadow stack support (return
-address tracking) from x86 Control-flow Enforcement Technology (CET).
-The option has effect only if the @option{-fcf-protection=full} or
-@option{-fcf-protection=return} option is specified. The option
-@option{-mshstk} is on by default when the @option{-mcet} option is
-specified.
+The @option{-mshstk} option enables shadow stack built-in functions
+from x86 Control-flow Enforcement Technology (CET).
@item -mcrc32
@opindex mcrc32
ABI-compatible library must be specified at link time.
GCC currently emits calls to @code{vmldExp2},
-@code{vmldLn2}, @code{vmldLog102}, @code{vmldLog102}, @code{vmldPow2},
+@code{vmldLn2}, @code{vmldLog102}, @code{vmldPow2},
@code{vmldTanh2}, @code{vmldTan2}, @code{vmldAtan2}, @code{vmldAtanh2},
@code{vmldCbrt2}, @code{vmldSinh2}, @code{vmldSin2}, @code{vmldAsinh2},
@code{vmldAsin2}, @code{vmldCosh2}, @code{vmldCos2}, @code{vmldAcosh2},
-@code{vmldAcos2}, @code{vmlsExp4}, @code{vmlsLn4}, @code{vmlsLog104},
+@code{vmldAcos2}, @code{vmlsExp4}, @code{vmlsLn4},
@code{vmlsLog104}, @code{vmlsPow4}, @code{vmlsTanh4}, @code{vmlsTan4},
@code{vmlsAtan4}, @code{vmlsAtanh4}, @code{vmlsCbrt4}, @code{vmlsSinh4},
@code{vmlsSin4}, @code{vmlsAsinh4}, @code{vmlsAsin4}, @code{vmlsCosh4},
function attribute @code{indirect_branch}. @xref{Function Attributes}.
Note that @option{-mcmodel=large} is incompatible with
-@option{-mindirect-branch=thunk} nor
+@option{-mindirect-branch=thunk} and
@option{-mindirect-branch=thunk-extern} since the thunk function may
-not be reachable in large code model.
+not be reachable in the large code model.
+
+Note that @option{-mindirect-branch=thunk-extern} is incompatible with
+@option{-fcf-protection=branch} since the external thunk can not be modified
+to disable control-flow check.
@item -mfunction-return=@var{choice}
@opindex -mfunction-return
@xref{Function Attributes}.
Note that @option{-mcmodel=large} is incompatible with
-@option{-mfunction-return=thunk} nor
+@option{-mfunction-return=thunk} and
@option{-mfunction-return=thunk-extern} since the thunk function may
-not be reachable in large code model.
+not be reachable in the large code model.
@item -mindirect-branch-register
projects / gcc.git / blobdiff