@xref{C++ Dialect Options,,Options Controlling C++ Dialect}.
@gccoptlist{-fabi-version=@var{n} -fno-access-control @gol
-faligned-new=@var{n} -fargs-in-order=@var{n} -fchar8_t -fcheck-new @gol
--fconstexpr-depth=@var{n} -fconstexpr-loop-limit=@var{n} @gol
--fconstexpr-ops-limit=@var{n} -fno-elide-constructors @gol
+-fconstexpr-depth=@var{n} -fconstexpr-cache-depth=@var{n} @gol
+-fconstexpr-loop-limit=@var{n} -fconstexpr-ops-limit=@var{n} @gol
+-fno-elide-constructors @gol
-fno-enforce-eh-specs @gol
-fno-gnu-keywords @gol
-fno-implicit-templates @gol
-fno-nonansi-builtins -fnothrow-opt -fno-operator-names @gol
-fno-optional-diags -fpermissive @gol
-fno-pretty-templates @gol
--frepo -fno-rtti -fsized-deallocation @gol
+-fno-rtti -fsized-deallocation @gol
-ftemplate-backtrace-limit=@var{n} @gol
-ftemplate-depth=@var{n} @gol
-fno-threadsafe-statics -fuse-cxa-atexit @gol
-fvisibility-inlines-hidden @gol
-fvisibility-ms-compat @gol
-fext-numeric-literals @gol
--Wabi=@var{n} -Wabi-tag -Wconversion-null -Wctor-dtor-privacy @gol
+-Wabi=@var{n} -Wabi-tag -Wcomma-subscript -Wconversion-null @gol
+-Wctor-dtor-privacy @gol
-Wdelete-non-virtual-dtor -Wdeprecated-copy -Wdeprecated-copy-dtor @gol
-Wliteral-suffix @gol
-Wmultiple-inheritance -Wno-init-list-lifetime @gol
-Wno-non-template-friend -Wold-style-cast @gol
-Woverloaded-virtual -Wno-pmf-conversions @gol
-Wno-class-conversion -Wno-terminate @gol
--Wsign-promo -Wvirtual-inheritance}
+-Wsign-promo -Wvirtual-inheritance -Wvolatile}
@item Objective-C and Objective-C++ Language Options
@xref{Objective-C and Objective-C++ Dialect Options,,Options Controlling
@gccoptlist{-fmessage-length=@var{n} @gol
-fdiagnostics-show-location=@r{[}once@r{|}every-line@r{]} @gol
-fdiagnostics-color=@r{[}auto@r{|}never@r{|}always@r{]} @gol
+-fdiagnostics-urls=@r{[}auto@r{|}never@r{|}always@r{]} @gol
-fdiagnostics-format=@r{[}text@r{|}json@r{]} @gol
-fno-diagnostics-show-option -fno-diagnostics-show-caret @gol
-fno-diagnostics-show-labels -fno-diagnostics-show-line-numbers @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 -Wc++17-compat @gol
+-Wc++20-compat @gol
-Wcast-align -Wcast-align=strict -Wcast-function-type -Wcast-qual @gol
-Wchar-subscripts -Wcatch-value -Wcatch-value=@var{n} @gol
-Wclobbered -Wcomment -Wconditionally-supported @gol
-Wno-discarded-qualifiers -Wno-discarded-array-qualifiers @gol
-Wno-div-by-zero -Wdouble-promotion @gol
-Wduplicated-branches -Wduplicated-cond @gol
--Wempty-body -Wenum-compare -Wno-endif-labels -Wexpansion-to-defined @gol
+-Wempty-body -Wenum-compare -Wenum-conversion @gol
+-Wno-endif-labels -Wexpansion-to-defined @gol
-Werror -Werror=* -Wextra-semi -Wfatal-errors @gol
-Wfloat-equal -Wformat -Wformat=2 @gol
-Wno-format-contains-nul -Wno-format-extra-args @gol
-Winaccessible-base @gol
-Winit-self -Winline -Wno-int-conversion -Wint-in-bool-context @gol
-Wno-int-to-pointer-cast -Winvalid-memory-model -Wno-invalid-offsetof @gol
+-Wzero-length-bounds @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
-Wno-pragmas -Wno-prio-ctor-dtor -Wredundant-decls @gol
-Wrestrict -Wno-return-local-addr @gol
-Wreturn-type -Wsequence-point -Wshadow -Wno-shadow-ivar @gol
--Wshadow=global, -Wshadow=local, -Wshadow=compatible-local @gol
+-Wshadow=global -Wshadow=local -Wshadow=compatible-local @gol
-Wshift-overflow -Wshift-overflow=@var{n} @gol
-Wshift-count-negative -Wshift-count-overflow -Wshift-negative-value @gol
-Wsign-compare -Wsign-conversion -Wfloat-conversion @gol
-Wsizeof-pointer-memaccess -Wsizeof-array-argument @gol
-Wstack-protector -Wstack-usage=@var{byte-size} -Wstrict-aliasing @gol
-Wstrict-aliasing=n -Wstrict-overflow -Wstrict-overflow=@var{n} @gol
+-Wstring-compare @gol
-Wstringop-overflow=@var{n} -Wstringop-truncation -Wsubobject-linkage @gol
-Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}malloc@r{]} @gol
-Wsuggest-final-types @gol -Wsuggest-final-methods -Wsuggest-override @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
+-fallow-store-data-races @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
--fbtr-bb-exclusive -fcaller-saves @gol
+-fcaller-saves @gol
-fcombine-stack-adjustments -fconserve-stack @gol
-fcompare-elim -fcprop-registers -fcrossjumping @gol
-fcse-follow-jumps -fcse-skip-blocks -fcx-fortran-rules @gol
-fsignaling-nans @gol
-fsingle-precision-constant -fsplit-ivs-in-unroller -fsplit-loops@gol
-fsplit-paths @gol
--fsplit-wide-types -fssa-backprop -fssa-phiopt @gol
+-fsplit-wide-types -fsplit-wide-types-early -fssa-backprop -fssa-phiopt @gol
-fstdarg-opt -fstore-merging -fstrict-aliasing @gol
-fthread-jumps -ftracer -ftree-bit-ccp @gol
-ftree-builtin-call-dce -ftree-ccp -ftree-ch @gol
@gccoptlist{-p -pg -fprofile-arcs --coverage -ftest-coverage @gol
-fprofile-abs-path @gol
-fprofile-dir=@var{path} -fprofile-generate -fprofile-generate=@var{path} @gol
--fprofile-update=@var{method} -fprofile-filter-files=@var{regex} @gol
--fprofile-exclude-files=@var{regex} @gol
+-fprofile-note=@var{path} -fprofile-update=@var{method} @gol
+-fprofile-filter-files=@var{regex} -fprofile-exclude-files=@var{regex} @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
-fdebug-cpp -fdirectives-only -fdollars-in-identifiers @gol
-fexec-charset=@var{charset} -fextended-identifiers @gol
-finput-charset=@var{charset} -fmacro-prefix-map=@var{old}=@var{new} @gol
+-fmax-include-depth=@var{depth} @gol
-fno-canonical-system-headers -fpch-deps -fpch-preprocess @gol
-fpreprocessed -ftabstop=@var{width} -ftrack-macro-expansion @gol
-fwide-exec-charset=@var{charset} -fworking-directory @gol
-march=@var{name} -mcpu=@var{name} -mtune=@var{name} @gol
-moverride=@var{string} -mverbose-cost-dump @gol
-mstack-protector-guard=@var{guard} -mstack-protector-guard-reg=@var{sysreg} @gol
--mstack-protector-guard-offset=@var{offset} -mtrack-speculation }
+-mstack-protector-guard-offset=@var{offset} -mtrack-speculation @gol
+-moutline-atomics }
@emph{Adapteva Epiphany Options}
@gccoptlist{-mhalf-reg-file -mprefer-short-insn-regs @gol
-mrestrict-it @gol
-mverbose-cost-dump @gol
-mpure-code @gol
--mcmse}
+-mcmse @gol
+-mfdpic}
@emph{AVR Options}
@gccoptlist{-mmcu=@var{mcu} -mabsdata -maccumulate-args @gol
-msmall-text -mlarge-text @gol
-mmemory-latency=@var{time}}
+@emph{eBPF Options}
+@gccoptlist{-mbig-endian -mlittle-endian -mkernel=@var{version}
+-mframe-limit=@var{bytes}}
+
@emph{FR30 Options}
@gccoptlist{-msmall-model -mno-lsim}
-mwarn-mcu @gol
-mcode-region= -mdata-region= @gol
-msilicon-errata= -msilicon-errata-warn= @gol
--mhwmult= -minrt}
+-mhwmult= -minrt -mtiny-printf}
@emph{NDS32 Options}
@gccoptlist{-mbig-endian -mlittle-endian @gol
@emph{OpenRISC Options}
@gccoptlist{-mboard=@var{name} -mnewlib -mhard-mul -mhard-div @gol
-msoft-mul -msoft-div @gol
--mcmov -mror -msext -msfimm -mshftimm}
+-msoft-float -mhard-float -mdouble-float -munordered-float @gol
+-mcmov -mror -mrori -msext -msfimm -mshftimm}
@emph{PDP-11 Options}
@gccoptlist{-mfpu -msoft-float -mac0 -mno-ac0 -m40 -m45 -m10 @gol
-mcmodel=medlow -mcmodel=medany @gol
-mexplicit-relocs -mno-explicit-relocs @gol
-mrelax -mno-relax @gol
--mriscv-attribute -mmo-riscv-attribute}
+-mriscv-attribute -mmo-riscv-attribute @gol
+-malign-data=@var{type}}
@emph{RL78 Options}
@gccoptlist{-msim -mmul=none -mmul=g13 -mmul=g14 -mallregs @gol
-mfix-at697f -mfix-ut699 -mfix-ut700 -mfix-gr712rc @gol
-mlra -mno-lra}
-@emph{SPU Options}
-@gccoptlist{-mwarn-reloc -merror-reloc @gol
--msafe-dma -munsafe-dma @gol
--mbranch-hints @gol
--msmall-mem -mlarge-mem -mstdmain @gol
--mfixed-range=@var{register-range} @gol
--mea32 -mea64 @gol
--maddress-space-conversion -mno-address-space-conversion @gol
--mcache-size=@var{cache-size} @gol
--matomic-updates -mno-atomic-updates}
-
@emph{System V Options}
@gccoptlist{-Qy -Qn -YP,@var{paths} -Ym,@var{dir}}
-mshstk -mmanual-endbr -mforce-indirect-call -mavx512vbmi2 -mavx512bf16 -menqcmd @gol
-mvpclmulqdq -mavx512bitalg -mmovdiri -mmovdir64b -mavx512vpopcntdq @gol
-mavx5124fmaps -mavx512vnni -mavx5124vnniw -mprfchw -mrdpid @gol
--mrdseed -msgx @gol
+-mrdseed -msgx -mavx512vp2intersect@gol
-mcldemote -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
Version 13, which first appeared in G++ 8.2, fixes the accidental
change in version 12.
+Version 14, which first appeared in G++ 10, corrects the mangling of
+the nullptr expression.
+
See also @option{-Wabi}.
@item -fabi-compat-version=@var{n}
@samp{new (nothrow)}.
@item -fconcepts
+@itemx -fconcepts-ts
@opindex fconcepts
-Enable support for the C++ Extensions for Concepts Technical
-Specification, ISO 19217 (2015), which allows code like
+@opindex fconcepts-ts
+Below @option{-std=c++2a}, @option{-fconcepts} enables support for the
+C++ Extensions for Concepts Technical Specification, ISO 19217 (2015).
-@smallexample
-template <class T> concept bool Addable = requires (T t) @{ t + t; @};
-template <Addable T> T add (T a, T b) @{ return a + b; @}
-@end smallexample
+With @option{-std=c++2a} and above, Concepts are part of the language
+standard, so @option{-fconcepts} defaults to on. But the standard
+specification of Concepts differs significantly from the TS, so some
+constructs that were allowed in the TS but didn't make it into the
+standard can still be enabled by @option{-fconcepts-ts}.
@item -fconstexpr-depth=@var{n}
@opindex fconstexpr-depth
constant expression evaluation. The minimum specified by the standard
is 512.
+@item -fconstexpr-cache-depth=@var{n}
+@opindex fconstexpr-cache-depth
+Set the maximum level of nested evaluation depth for C++11 constexpr
+functions that will be cached to @var{n}. This is a heuristic that
+trades off compilation speed (when the cache avoids repeated
+calculations) against memory consumption (when the cache grows very
+large from highly recursive evaluations). The default is 8. Very few
+users are likely to want to adjust it, but if your code does heavy
+constexpr calculations you might want to experiment to find which
+value works best for you.
+
@item -fconstexpr-loop-limit=@var{n}
@opindex fconstexpr-loop-limit
Set the maximum number of iterations for a loop in C++14 constexpr functions
evaluation might take too long.
The default is 33554432 (1<<25).
-@item -fdeduce-init-list
-@opindex fdeduce-init-list
-Enable deduction of a template type parameter as
-@code{std::initializer_list} from a brace-enclosed initializer list, i.e.@:
-
-@smallexample
-template <class T> auto forward(T t) -> decltype (realfn (t))
-@{
- return realfn (t);
-@}
-
-void f()
-@{
- forward(@{1,2@}); // call forward<std::initializer_list<int>>
-@}
-@end smallexample
-
-This deduction was implemented as a possible extension to the
-originally proposed semantics for the C++11 standard, but was not part
-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 -fno-elide-constructors
@opindex fno-elide-constructors
@opindex felide-constructors
behaviors make it harder to understand the error message rather than
easier, you can use @option{-fno-pretty-templates} to disable them.
-@item -frepo
-@opindex frepo
-Enable automatic template instantiation at link time. This option also
-implies @option{-fno-implicit-templates}. @xref{Template
-Instantiation}, for more information.
-
@item -fno-rtti
@opindex fno-rtti
@opindex frtti
have that ABI tag. See @ref{C++ Attributes} for more information
about ABI tags.
+@item -Wcomma-subscript @r{(C++ and Objective-C++ only)}
+@opindex Wcomma-subscript
+@opindex Wno-comma-subscript
+Warn about uses of a comma expression within a subscripting expression.
+This usage was deprecated in C++2a. However, a comma expression wrapped
+in @code{( )} is not deprecated. Example:
+
+@smallexample
+@group
+void f(int *a, int b, int c) @{
+ a[b,c]; // deprecated
+ a[(b,c)]; // OK
+@}
+@end group
+@end smallexample
+
+Enabled by default with @option{-std=c++2a}.
+
@item -Wctor-dtor-privacy @r{(C++ and Objective-C++ only)}
@opindex Wctor-dtor-privacy
@opindex Wno-ctor-dtor-privacy
Disable the warning about the case when a conversion function converts an
object to the same type, to a base class of that type, or to void; such
a conversion function will never be called.
+
+@item -Wvolatile @r{(C++ and Objective-C++ only)}
+@opindex Wvolatile
+@opindex Wno-volatile
+Warn about deprecated uses of the @code{volatile} qualifier. This includes
+postfix and prefix @code{++} and @code{--} expressions of
+@code{volatile}-qualified types, using simple assignments where the left
+operand is a @code{volatile}-qualified non-class type for their value,
+compound assignments where the left operand is a @code{volatile}-qualified
+non-class type, @code{volatile}-qualified function return type,
+@code{volatile}-qualified parameter type, and structured bindings of a
+@code{volatile}-qualified type. This usage was deprecated in C++20.
+
+Enabled by default with @option{-std=c++2a}.
@end table
@node Objective-C and Objective-C++ Dialect Options
arguments in the C++ frontend.
@end table
+@item -fdiagnostics-urls[=@var{WHEN}]
+@opindex fdiagnostics-urls
+@cindex urls
+Use escape sequences to embed URLs in diagnostics. For example, when
+@option{-fdiagnostics-show-option} emits text showing the command-line
+option controlling a diagnostic, embed a URL for documentation of that
+option.
+
+@var{WHEN} is @samp{never}, @samp{always}, or @samp{auto}.
+The default is @samp{auto}, which means to use URL escape sequences only
+when the standard error is a terminal.
+
@item -fno-diagnostics-show-option
@opindex fno-diagnostics-show-option
@opindex fdiagnostics-show-option
],
"message": "this \u2018if\u2019 clause does not guard...",
"option": "-Wmisleading-indentation",
+ "option_url": "https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wmisleading-indentation",
"children": [
@{
"kind": "note",
-Wcomment @gol
-Wduplicate-decl-specifier @r{(C and Objective-C only)} @gol
-Wenum-compare @r{(in C/ObjC; this is on by default in C++)} @gol
+-Wenum-conversion @r{in C/ObjC;} @gol
-Wformat @gol
-Wint-in-bool-context @gol
-Wimplicit @r{(C and Objective-C only)} @gol
-Wimplicit-int @r{(C and Objective-C only)} @gol
-Wimplicit-function-declaration @r{(C and Objective-C only)} @gol
-Winit-self @r{(only for C++)} @gol
+-Wzero-length-bounds @gol
-Wlogical-not-parentheses @gol
-Wmain @r{(only for C/ObjC and unless} @option{-ffreestanding}@r{)} @gol
-Wmaybe-uninitialized @gol
-Wold-style-declaration @r{(C only)} @gol
-Woverride-init @gol
-Wsign-compare @r{(C only)} @gol
+-Wstring-compare @gol
-Wredundant-move @r{(only for C++)} @gol
-Wtype-limits @gol
-Wuninitialized @gol
@item -Wuninitialized
@opindex Wuninitialized
@opindex Wno-uninitialized
-Warn if an automatic variable is used without first being initialized
-or if a variable may be clobbered by a @code{setjmp} call. In C++,
-warn if a non-static reference or non-static @code{const} member
-appears in a class without constructors.
+Warn if an automatic variable is used without first being initialized.
+In C++, warn if a non-static reference or non-static @code{const}
+member appears in a class without constructors.
If you want to warn about code that uses the uninitialized value of the
variable in its own initializer, use the @option{-Winit-self} option.
-These warnings occur for individual uninitialized or clobbered
-elements of structure, union or array variables as well as for
-variables that are uninitialized or clobbered as a whole. They do
-not occur for variables or elements declared @code{volatile}. Because
-these warnings depend on optimization, the exact variables or elements
-for which there are warnings depends on the precise optimization
-options and version of GCC used.
+These warnings occur for individual uninitialized elements of
+structure, union or array variables as well as for variables that are
+uninitialized as a whole. They do not occur for variables or elements
+declared @code{volatile}. Because these warnings depend on
+optimization, the exact variables or elements for which there are
+warnings depend on the precise optimization options and version of GCC
+used.
Note that there may be no warning about a variable that is used only
to compute a value that itself is never used, because such
false positives.
@end table
+@item -Wstring-compare
+@opindex Wstring-compare
+@opindex Wno-string-compare
+Warn for calls to @code{strcmp} and @code{strncmp} whose result is
+determined to be either zero or non-zero in tests for such equality
+owing to the length of one argument being greater than the size of
+the array the other argument is stored in (or the bound in the case
+of @code{strncmp}). Such calls could be mistakes. For example,
+the call to @code{strcmp} below is diagnosed because its result is
+necessarily non-zero irrespective of the contents of the array @code{a}.
+
+@smallexample
+extern char a[4];
+void f (char *d)
+@{
+ strcpy (d, "string");
+ @dots{}
+ if (0 == strcmp (a, d)) // cannot be true
+ puts ("a and d are the same");
+@}
+@end smallexample
+
+@option{-Wstring-compare} is enabled by @option{-Wextra}.
+
@item -Wstringop-overflow
@itemx -Wstringop-overflow=@var{type}
@opindex Wstringop-overflow
if the type were declared with the C++11 @code{final} specifier,
or, if possible,
declared in an anonymous namespace. This allows GCC to more aggressively
-devirtualize the polymorphic calls. This warning is more effective with link
-time optimization, where the information about the class hierarchy graph is
+devirtualize the polymorphic calls. This warning is more effective with
+link-time optimization,
+where the information about the class hierarchy graph is
more complete.
@item -Wsuggest-final-methods
@item -Wattribute-alias=@var{n}
@itemx -Wno-attribute-alias
-@opindex -Wattribute-alias
-@opindex -Wno-attribute-alias
+@opindex Wattribute-alias
+@opindex Wno-attribute-alias
Warn about declarations using the @code{alias} and similar attributes whose
target is incompatible with the type of the alias.
@xref{Function Attributes,,Declaring Attributes of Functions}.
@opindex Wno-discarded-array-qualifiers
@opindex Wdiscarded-array-qualifiers
Do not warn if type qualifiers on arrays which are pointer targets
-are being discarded. Typically, the compiler warns if a
+are being discarded. Typically, the compiler warns if a
@code{const int (*)[]} variable is passed to a function that
takes a @code{int (*)[]} parameter. This option can be used to
suppress such a warning.
conversions the warnings @option{-Wno-int-to-pointer-cast} and
@option{-Wno-pointer-to-int-cast} may be used.
+@item -Wzero-length-bounds
+@opindex Wzero-length-bounds
+@opindex Wzero-length-bounds
+Warn about accesses to elements of zero-length array members that might
+overlap other members of the same object. Declaring interior zero-length
+arrays is discouraged because accesses to them are undefined. See
+@xref{Zero Length}.
+
+For example, the first two stores in function @code{bad} are diagnosed
+because the array elements overlap the subsequent members @code{b} and
+@code{c}. The third store is diagnosed by @option{-Warray-bounds}
+because it is beyond the bounds of the enclosing object.
+
+@smallexample
+struct X @{ int a[0]; int b, c; @};
+struct X x;
+
+void bad (void)
+@{
+ x.a[0] = 0; // -Wzero-length-bounds
+ x.a[1] = 1; // -Wzero-length-bounds
+ x.a[2] = 2; // -Warray-bounds
+@}
+@end smallexample
+
+Option @option{-Wzero-length-bounds} is enabled by @option{-Warray-bounds}.
+
@item -Wno-div-by-zero
@opindex Wno-div-by-zero
@opindex Wdiv-by-zero
@opindex Wno-shadow
Warn whenever a local variable or type declaration shadows another
variable, parameter, type, class member (in C++), or instance variable
-(in Objective-C) or whenever a built-in function is shadowed. Note
+(in Objective-C) or whenever a built-in function is shadowed. Note
that in C++, the compiler warns if a local variable shadows an
explicit typedef, but not if it shadows a struct/class/enum.
+If this warning is enabled, it includes also all instances of
+local shadowing. This means that @option{-Wno-shadow=local}
+and @option{-Wno-shadow=compatible-local} are ignored when
+@option{-Wshadow} is used.
Same as @option{-Wshadow=global}.
@item -Wno-shadow-ivar @r{(Objective-C only)}
Objective-C method.
@item -Wshadow=global
-@opindex Wshadow=local
-The default for @option{-Wshadow}. Warns for any (global) shadowing.
+@opindex Wshadow=global
+Warn for any shadowing.
+Same as @option{-Wshadow}.
@item -Wshadow=local
@opindex Wshadow=local
Warn when a local variable shadows another local variable or parameter.
-This warning is enabled by @option{-Wshadow=global}.
@item -Wshadow=compatible-local
@opindex Wshadow=compatible-local
Warn when a local variable shadows another local variable or parameter
-whose type is compatible with that of the shadowing variable. In C++,
+whose type is compatible with that of the shadowing variable. In C++,
type compatibility here means the type of the shadowing variable can be
-converted to that of the shadowed variable. The creation of this flag
+converted to that of the shadowed variable. The creation of this flag
(in addition to @option{-Wshadow=local}) is based on the idea that when
a local variable shadows another one of incompatible type, it is most
likely intentional, not a bug or typo, as shown in the following example:
@end smallexample
Since the two variable @code{i} in the example above have incompatible types,
-enabling only @option{-Wshadow=compatible-local} will not emit a warning.
+enabling only @option{-Wshadow=compatible-local} does not emit a warning.
Because their types are incompatible, if a programmer accidentally uses one
-in place of the other, type checking will catch that and emit an error or
-warning. So not warning (about shadowing) in this case will not lead to
-undetected bugs. Use of this flag instead of @option{-Wshadow=local} can
+in place of the other, type checking is expected to catch that and emit an
+error or warning. Use of this flag instead of @option{-Wshadow=local} can
possibly reduce the number of warnings triggered by intentional shadowing.
+Note that this also means that shadowing @code{const char *i} by
+@code{char *i} does not emit a warning.
-This warning is enabled by @option{-Wshadow=local}.
+This warning is also enabled by @option{-Wshadow=local}.
@item -Wlarger-than=@var{byte-size}
@opindex Wlarger-than=
Warn about C++ constructs whose meaning differs between ISO C++ 2014
and ISO C++ 2017. This warning is enabled by @option{-Wall}.
+@item -Wc++20-compat @r{(C++ and Objective-C++ only)}
+@opindex Wc++20-compat
+@opindex Wno-c++20-compat
+Warn about C++ constructs whose meaning differs between ISO C++ 2017
+and ISO C++ 2020. This warning is enabled by @option{-Wall}.
+
@item -Wcast-qual
@opindex Wcast-qual
@opindex Wno-cast-qual
diagnosed and the warning is enabled by default. In C this warning is
enabled by @option{-Wall}.
+@item -Wenum-conversion @r{(C, Objective-C only)}
+@opindex Wenum-conversion
+@opindex Wno-enum-conversion
+Warn when a value of enumerated type is implicitly converted to a
+different enumerated type. This warning is enabled by @option{-Wextra}.
+
@item -Wextra-semi @r{(C++, Objective-C++ only)}
@opindex Wextra-semi
@opindex Wno-extra-semi
-ffinite-loops @gol
-fgcse -fgcse-lm @gol
-fhoist-adjacent-loads @gol
+-finline-functions @gol
-finline-small-functions @gol
-findirect-inlining @gol
-fipa-bit-cp -fipa-cp -fipa-icf @gol
@c Please keep the following list alphabetized!
@gccoptlist{-fgcse-after-reload @gol
--finline-functions @gol
-fipa-cp-clone
-floop-interchange @gol
-floop-unroll-and-jam @gol
Disregard strict standards compliance. @option{-Ofast} enables all
@option{-O3} optimizations. It also enables optimizations that are not
valid for all standard-compliant programs.
-It turns on @option{-ffast-math} and the Fortran-specific
-@option{-fstack-arrays}, unless @option{-fmax-stack-var-size} is
-specified, and @option{-fno-protect-parens}.
+It turns on @option{-ffast-math}, @option{-fallow-store-data-races}
+and the Fortran-specific @option{-fstack-arrays}, unless
+@option{-fmax-stack-var-size} is specified, and @option{-fno-protect-parens}.
@item -Og
@opindex Og
optimization flags except for those that may interfere with debugging:
@gccoptlist{-fbranch-count-reg -fdelayed-branch @gol
--fif-conversion -fif-conversion2 @gol
+-fdse -fif-conversion -fif-conversion2 @gol
-finline-functions-called-once @gol
-fmove-loop-invariants -fssa-phiopt @gol
--ftree-bit-ccp -ftree-pta -ftree-sra}
+-ftree-bit-ccp -ftree-dse -ftree-pta -ftree-sra}
@end table
declared @code{static}, then the function is normally not output as
assembler code in its own right.
-Enabled at levels @option{-O3}, @option{-Os}. Also enabled
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}. Also enabled
by @option{-fprofile-use} and @option{-fauto-profile}.
@item -finline-functions-called-once
Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
@option{-Os}.
+@item -fsplit-wide-types-early
+@opindex fsplit-wide-types-early
+Fully split wide types early, instead of very late.
+This option has no effect unless @option{-fsplit-wide-types} is turned on.
+
+This is the default on some targets.
+
@item -fcse-follow-jumps
@opindex fcse-follow-jumps
In common subexpression elimination (CSE), scan through jump instructions
With this option, the compiler creates multiple copies of some
local variables when unrolling a loop, which can result in superior code.
+This optimization is enabled by default for PowerPC targets, but disabled
+by default otherwise.
+
@item -fpartial-inlining
@opindex fpartial-inlining
Inline parts of functions. This option has any effect only
Enabled at levels @option{-O2}, @option{-O3}.
+@item -fallow-store-data-races
+@opindex fallow-store-data-races
+Allow the compiler to introduce new data races on stores.
+
+Enabled at level @option{-Ofast}.
+
@item -funit-at-a-time
@opindex funit-at-a-time
This option is left for compatibility reasons. @option{-funit-at-a-time}
precedence; and for example @option{-ffp-contract=off} takes precedence
over @option{-ffp-contract=fast}. You can override them at link time.
+To enable debug info generation you need to supply @option{-g} at
+compile-time. If any of the input files at link time were built
+with debug info generation enabled the link will enable debug info
+generation as well. Any elaborate debug info settings
+like the dwarf level @option{-gdwarf-5} need to be explicitly repeated
+at the linker command line and mixing different settings in different
+translation units is discouraged.
+
If LTO encounters objects with C linkage declared with incompatible
types in separate translation units to be linked together (undefined
behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be
generation done at link time is executed in parallel using @var{n}
parallel jobs by utilizing an installed @command{make} program. The
environment variable @env{MAKE} may be used to override the program
-used. The default value for @var{n} is 1.
+used.
You can also specify @option{-flto=jobserver} to use GNU make's
job server mode to determine the number of parallel jobs. This
is useful when the Makefile calling GCC is already executing in parallel.
You must prepend a @samp{+} to the command recipe in the parent Makefile
for this to work. This option likely only works if @env{MAKE} is
-GNU make.
+GNU make. Even without the option value, GCC tries to automatically
+detect a running GNU make's job server.
+
+Use @option{-flto=auto} to use GNU make's job server, if available,
+or otherwise fall back to autodetection of the number of CPU threads
+present in your system.
@item -flto-partition=@var{alg}
@opindex flto-partition
double} variants, to generate code that raises the ``inexact''
floating-point exception for noninteger arguments. ISO C99 and C11
allow these functions to raise the ``inexact'' exception, but ISO/IEC
-TS 18661-1:2014, the C bindings to IEEE 754-2008, does not allow these
-functions to do so.
+TS 18661-1:2014, the C bindings to IEEE 754-2008, as integrated into
+ISO C2X, does not allow these functions to do so.
The default is @option{-ffp-int-builtin-inexact}, allowing the
-exception to be raised. This option does nothing unless
-@option{-ftrapping-math} is in effect.
+exception to be raised, unless C2X or a later C standard is selected.
+This option does nothing unless @option{-ftrapping-math} is in effect.
Even if @option{-fno-fp-int-builtin-inexact} is used, if the functions
generate a call to a library function then the ``inexact'' exception
link time. An example of such an optimization is relaxing calls to short call
instructions.
-@item -fbranch-target-load-optimize
-@opindex fbranch-target-load-optimize
-Perform branch target register load optimization before prologue / epilogue
-threading.
-The use of target registers can typically be exposed only during reload,
-thus hoisting loads out of loops and doing inter-block scheduling needs
-a separate optimization pass.
-
-@item -fbranch-target-load-optimize2
-@opindex fbranch-target-load-optimize2
-Perform branch target register load optimization after prologue / epilogue
-threading.
-
-@item -fbtr-bb-exclusive
-@opindex fbtr-bb-exclusive
-When performing branch target register load optimization, don't reuse
-branch target registers within any basic block.
-
@item -fstdarg-opt
@opindex fstdarg-opt
Optimize the prologue of variadic argument functions with respect to usage of
compilation time.
@item max-inline-insns-single
-Several parameters control the tree inliner used in GCC@.
-This number sets the maximum number of instructions (counted in GCC's
-internal representation) in a single function that the tree inliner
-considers for inlining. This only affects functions declared
-inline and methods implemented in a class declaration (C++).
+@item max-inline-insns-single-O2
+Several parameters control the tree inliner used in GCC@. This number sets the
+maximum number of instructions (counted in GCC's internal representation) in a
+single function that the tree inliner considers for inlining. This only
+affects functions declared inline and methods implemented in a class
+declaration (C++).
+
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{max-inline-insns-single} is
+applied. In other cases @option{max-inline-insns-single-O2} is applied.
+
@item max-inline-insns-auto
+@item max-inline-insns-auto-O2
When you use @option{-finline-functions} (included in @option{-O3}),
a lot of functions that would otherwise not be considered for inlining
by the compiler are investigated. To those functions, a different
(more restrictive) limit compared to functions declared inline can
be applied.
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{max-inline-insns-auto} is
+applied. In other cases @option{max-inline-insns-auto-O2} is applied.
+
@item max-inline-insns-small
This is bound applied to calls which are considered relevant with
@option{-finline-small-functions}.
Extra time accounted by inliner for function overhead such as time needed to
execute function prologue and epilogue
+@item inline-heuristics-hint-percent
+@item inline-heuristics-hint-percent-O2
+The scale (in percents) applied to @option{inline-insns-single},
+@option{inline-insns-single-O2}, @option{inline-insns-auto},
+@option{inline-insns-auto-O2} when inline heuristics hints that inlining is
+very profitable (will enable later optimizations).
+
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter
+@option{inline-heuristics-hint-percent} is applied. In other cases
+@option{inline-heuristics-hint-percent-O2} is applied.
+
@item uninlined-thunk-insns
@item uninlined-thunk-time
Same as @option{--param uninlined-function-insns} and
@option{--param uninlined-function-time} but applied to function thunks
@item inline-min-speedup
+@item inline-min-speedup-O2
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}.
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{inline-min-speedup} is
+applied. In other cases @option{inline-min-speedup-O2} is applied.
+
@item large-function-insns
The limit specifying really large functions. For functions larger than this
limit after inlining, inlining is constrained by
expressions whose probability exceeds the given threshold (in percents).
@item early-inlining-insns
+@item early-inlining-insns-O2
Specify growth that the early inliner can make. In effect it increases
the amount of inlining for code having a large abstraction penalty.
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{early-inlining-insns} is
+applied. In other cases @option{early-inlining-insns-O2} is applied.
+
@item max-early-inliner-iterations
Limit of iterations of the early inliner. This basically bounds
the number of nested indirect calls the early inliner can resolve.
The maximum number of iterations of a loop the brute-force algorithm
for analysis of the number of iterations of the loop tries to evaluate.
+@item hot-bb-count-fraction
+The denominator n of fraction 1/n of the maximal execution count of a
+basic block in the entire program that a basic block needs to at least
+have in order to be considered hot. The default is 10000, which means
+that a basic block is considered hot if its execution count is greater
+than 1/10000 of the maximal execution count. 0 means that it is never
+considered hot. Used in non-LTO mode.
+
@item hot-bb-count-ws-permille
-A basic block profile count is considered hot if it contributes to
-the given permillage (i.e.@: 0...1000) of the entire profiled execution.
+The number of most executed permilles, ranging from 0 to 1000, of the
+profiled execution of the entire program to which the execution count
+of a basic block must be part of in order to be considered hot. The
+default is 990, which means that a basic block is considered hot if
+its execution count contributes to the upper 990 permilles, or 99.0%,
+of the profiled execution of the entire program. 0 means that it is
+never considered hot. Used in LTO mode.
@item hot-bb-frequency-fraction
-Select fraction of the entry block frequency of executions of basic block in
-function given basic block needs to have to be considered hot.
+The denominator n of fraction 1/n of the execution frequency of the
+entry block of a function that a basic block of this function needs
+to at least have in order to be considered hot. The default is 1000,
+which means that a basic block is considered hot in a function if it
+is executed more frequently than 1/1000 of the frequency of the entry
+block of the function. 0 means that it is never considered hot.
+
+@item unlikely-bb-count-fraction
+The denominator n of fraction 1/n of the number of profiled runs of
+the entire program below which the execution count of a basic block
+must be in order for the basic block to be considered unlikely executed.
+The default is 20, which means that a basic block is considered unlikely
+executed if it is executed in fewer than 1/20, or 5%, of the runs of
+the program. 0 means that it is always considered unlikely executed.
@item max-predicted-iterations
The maximum number of loop iterations we predict statically. This is useful
@option{ipa-sra-ptr-growth-factor} times the size of the original
pointer parameter.
+@item ipa-sra-max-replacements
+Maximum pieces of an aggregate that IPA-SRA tracks. As a
+consequence, it is also the maximum number of replacements of a formal
+parameter.
+
@item sra-max-scalarization-size-Ospeed
@itemx sra-max-scalarization-size-Osize
The two Scalar Reduction of Aggregates passes (SRA and IPA-SRA) aim to
@option{ipa-cp-loop-hint-bonus} to the profitability score of
the candidate.
-@item ipa-cp-array-index-hint-bonus
-When IPA-CP determines that a cloning candidate would make the index of
-an array access known, it adds a bonus of
-@option{ipa-cp-array-index-hint-bonus} to the profitability
-score of the candidate.
-
@item ipa-max-aa-steps
During its analysis of function bodies, IPA-CP employs alias analysis
in order to track values pointed to by function parameters. In order
consider all memory clobbered after examining
@option{ipa-max-aa-steps} statements modifying memory.
+@item ipa-max-switch-predicate-bounds
+Maximal number of boundary endpoints of case ranges of switch statement.
+For switch exceeding this limit, IPA-CP will not construct cloning cost
+predicate, which is used to estimate cloning benefit, for default case
+of the switch statement.
+
+@item ipa-max-param-expr-ops
+IPA-CP will analyze conditional statement that references some function
+parameter to estimate benefit for cloning upon certain constant value.
+But if number of operations in a parameter expression exceeds
+@option{ipa-max-param-expr-ops}, the expression is treated as complicated
+one, and is not handled by IPA analysis.
+
@item lto-partitions
Specify desired number of partitions produced during WHOPR compilation.
The number of partitions should exceed the number of CPUs used for compilation.
if either vectorization (@option{-ftree-vectorize}) or if-conversion
(@option{-ftree-loop-if-convert}) is disabled.
-@item allow-store-data-races
-Allow optimizers to introduce new data races on stores.
-Set to 1 to allow, otherwise to 0.
-
@item case-values-threshold
The smallest number of different values for which it is best to use a
jump-table instead of a tree of conditional branches. If the value is
The number of cycles the swing modulo scheduler considers when checking
conflicts using DFA.
-@item hot-bb-count-fraction
-Select fraction of the maximal count of repetitions of basic block
-in program given basic block needs
-to have to be considered hot (used in non-LTO mode)
-
@item max-inline-insns-recursive-auto
The maximum number of instructions non-inline function
can grow to via recursive inlining.
@item max-vartrack-reverse-op-size
Max. size of loc list for which reverse ops should be added.
-@item unlikely-bb-count-fraction
-The minimum fraction of profile runs a given basic block execution count
-must be not to be considered unlikely.
-
@item tracer-dynamic-coverage-feedback
The percentage of function, weighted by execution frequency,
that must be covered by trace formation.
discounting any instructions in inner loops that directly benefit
from versioning.
+@item ssa-name-def-chain-limit
+The maximum number of SSA_NAME assignments to follow in determining
+a property of a variable such as its value. This limits the number
+of iterations or recursive calls GCC performs when optimizing certain
+statements or when determining their validity prior to issuing
+diagnostics.
+
@end table
@end table
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.
+@file{.gcda} file. See similar option @option{-fprofile-note}.
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
To optimize the program based on the collected profile information, use
@option{-fprofile-use}. @xref{Optimize Options}, for more information.
+@item -fprofile-note=@var{path}
+@opindex fprofile-note
+
+If @var{path} is specified, GCC saves @file{.gcno} file into @var{path}
+location. If you combine the option with multiple source files,
+the @file{.gcno} file will be overwritten.
+
@item -fprofile-update=@var{method}
@opindex fprofile-update
@item -flinker-output=@var{type}
@opindex flinker-output
-This option controls code generation of the link time optimizer. By
+This option controls code generation of the link-time optimizer. By
default the linker output is automatically determined by the linker
plugin. For debugging the compiler and if incremental linking with a
non-LTO object file is desired, it may be useful to control the type
manually.
-If @var{type} is @samp{exec} code generation produces a static
+If @var{type} is @samp{exec}, code generation produces a static
binary. In this case @option{-fpic} and @option{-fpie} are both
disabled.
-If @var{type} is @samp{dyn} code generation produces a shared
+If @var{type} is @samp{dyn}, code generation produces a shared
library. In this case @option{-fpic} or @option{-fPIC} is preserved,
but not enabled automatically. This allows to build shared libraries
-without position independent code on architectures where this is
+without position-independent code on architectures where this is
possible, i.e.@: on x86.
-If @var{type} is @samp{pie} code generation produces an @option{-fpie}
+If @var{type} is @samp{pie}, code generation produces an @option{-fpie}
executable. This results 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
+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
+@option{-ffat-lto-objects} is specified, binary code is produced for future
+non-LTO linking. The object file produced by incremental linking is 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
+result of incremental linking also loads faster than a static
library assuming that the majority of objects in the library are used.
Finally @samp{nolto-rel} configures the compiler for incremental linking where
-code generation is forced, a final binary is produced and the intermediate
+code generation is forced, a 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, cross-module inlining will
-happen), most of benefits of whole program optimizations are however lost.
+are linked together the resulting code is better optimized than with
+link-time optimizations disabled (for example, cross-module inlining
+happens), but most of benefits of whole program optimizations are lost.
-During the incremental link (by @option{-r}) the linker plugin will default to
+During the incremental link (by @option{-r}) the linker plugin defaults to
@option{rel}. With current interfaces to GNU Binutils it is however not
possible to incrementally link LTO objects and non-LTO objects into a single
-mixed object file. In the case any of object files in incremental link cannot
-be used for link-time optimization the linker plugin will issue a warning and
-use @samp{nolto-rel}. To maintain the whole program optimization it is
+mixed object file. If any of object files in incremental link cannot
+be used for link-time optimization, the linker plugin issues a warning and
+uses @samp{nolto-rel}. To maintain 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 -flto-report-wpa
@opindex flto-report-wpa
-Like @option{-flto-report}, but only print for the WPA phase of Link
-Time Optimization.
+Like @option{-flto-report}, but only print for the WPA phase of link-time
+optimization.
@item -fmem-report
@opindex fmem-report
* C-SKY Options::
* Darwin Options::
* DEC Alpha Options::
+* eBPF Options::
* FR30 Options::
* FT32 Options::
* FRV Options::
* SH Options::
* Solaris 2 Options::
* SPARC Options::
-* SPU Options::
* System V Options::
* TILE-Gx Options::
* TILEPro Options::
@code{__builtin_speculation_safe_copy} to permit a more efficient code
sequence to be generated.
+@item -moutline-atomics
+@itemx -mno-outline-atomics
+Enable or disable calls to out-of-line helpers to implement atomic operations.
+These helpers will, at runtime, determine if the LSE instructions from
+ARMv8.1-A can be used; if not, they will use the load/store-exclusive
+instructions that are present in the base ARMv8.0 ISA.
+
+This option is only applicable when compiling for the base ARMv8.0
+instruction set. If using a later revision, e.g. @option{-march=armv8.1-a}
+or @option{-march=armv8-a+lse}, the ARMv8.1-Atomics instructions will be
+used directly. The same applies when using @option{-mcpu=} when the
+selected cpu supports the @samp{lse} feature.
+
@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{cortex-a76}, @samp{ares}, @samp{exynos-m1}, @samp{emag}, @samp{falkor},
+@samp{cortex-a76}, @samp{cortex-a76ae}, @samp{cortex-a77},
+@samp{cortex-a65}, @samp{cortex-a65ae}, @samp{cortex-a34},
+@samp{ares}, @samp{exynos-m1}, @samp{emag}, @samp{falkor},
@samp{neoverse-e1},@samp{neoverse-n1},@samp{qdf24xx}, @samp{saphira},
@samp{phecda}, @samp{xgene1}, @samp{vulcan}, @samp{octeontx},
@samp{octeontx81}, @samp{octeontx83}, @samp{thunderx}, @samp{thunderxt88},
@item sve2
Enable the Armv8-a Scalable Vector Extension 2. This also enables SVE
instructions.
-@item bitperm
+@item sve2-bitperm
Enable SVE2 bitperm instructions. This also enables SVE2 instructions.
@item sve2-sm4
Enable SVE2 sm4 instructions. This also enables SVE2 instructions.
@item sve2-sha3
Enable SVE2 sha3 instructions. This also enables SVE2 instructions.
@option{-march=armv8.5-a}.
+@item tme
+Enable the Transactional Memory Extension.
@end table
@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-a76}, @samp{ares}, @samp{cortex-r4}, @samp{cortex-r4f},
+@samp{cortex-a76}, @samp{cortex-a76ae}, @samp{cortex-a77},
+@samp{ares}, @samp{cortex-r4}, @samp{cortex-r4f},
@samp{cortex-r5}, @samp{cortex-r7}, @samp{cortex-r8}, @samp{cortex-r52},
@samp{cortex-m0}, @samp{cortex-m0plus}, @samp{cortex-m1}, @samp{cortex-m3},
@samp{cortex-m4}, @samp{cortex-m7}, @samp{cortex-m23}, @samp{cortex-m33},
+@samp{cortex-m35p},
@samp{cortex-m1.small-multiply}, @samp{cortex-m0.small-multiply},
@samp{cortex-m0plus.small-multiply}, @samp{exynos-m1}, @samp{marvell-pj4},
@samp{neoverse-n1}, @samp{xscale}, @samp{iwmmxt}, @samp{iwmmxt2},
@table @samp
@item +nodsp
-Disable the DSP instructions on @samp{cortex-m33}.
+Disable the DSP instructions on @samp{cortex-m33}, @samp{cortex-m35p}.
@item +nofp
Disables the floating-point instructions on @samp{arm9e},
@samp{arm946e-s}, @samp{arm966e-s}, @samp{arm968e-s}, @samp{arm10e},
@samp{arm1020e}, @samp{arm1022e}, @samp{arm926ej-s},
@samp{arm1026ej-s}, @samp{cortex-r5}, @samp{cortex-r7}, @samp{cortex-r8},
-@samp{cortex-m4}, @samp{cortex-m7} and @samp{cortex-m33}.
+@samp{cortex-m4}, @samp{cortex-m7}, @samp{cortex-m33} and @samp{cortex-m35p}.
Disables the floating-point and SIMD instructions on
@samp{generic-armv7-a}, @samp{cortex-a5}, @samp{cortex-a7},
@samp{cortex-a8}, @samp{cortex-a9}, @samp{cortex-a12},
@item -mneon-for-64bits
@opindex mneon-for-64bits
-Enables using Neon to handle scalar 64-bits operations. This is
-disabled by default since the cost of moving data from core registers
-to Neon is high.
+This option is deprecated and has no effect.
@item -mslow-flash-data
@opindex mslow-flash-data
Generate secure code as per the "ARMv8-M Security Extensions: Requirements on
Development Tools Engineering Specification", which can be found on
@url{http://infocenter.arm.com/help/topic/com.arm.doc.ecm0359818/ECM0359818_armv8m_security_extensions_reqs_on_dev_tools_1_0.pdf}.
+
+@item -mfdpic
+@itemx -mno-fdpic
+@opindex mfdpic
+@opindex mno-fdpic
+Select the FDPIC ABI, which uses 64-bit function descriptors to
+represent pointers to functions. When the compiler is configured for
+@code{arm-*-uclinuxfdpiceabi} targets, this option is on by default
+and implies @option{-fPIE} if none of the PIC/PIE-related options is
+provided. On other targets, it only enables the FDPIC-specific code
+generation features, and the user should explicitly provide the
+PIC/PIE-related options as needed.
+
+Note that static linking is not supported because it would still
+involve the dynamic linker when the program self-relocates. If such
+behavior is acceptable, use -static and -Wl,-dynamic-linker options.
+
+The opposite @option{-mno-fdpic} option is useful (and required) to
+build the Linux kernel using the same (@code{arm-*-uclinuxfdpiceabi})
+toolchain as the one used to build the userland programs.
+
@end table
@node AVR Options
@end table
@end table
+@node eBPF Options
+@subsection eBPF Options
+@cindex eBPF Options
+
+@table @gcctabopt
+@item -mframe-limit=@var{bytes}
+This specifies the hard limit for frame sizes, in bytes. Currently,
+the value that can be specified should be less than or equal to
+@samp{32767}. Defaults to whatever limit is imposed by the version of
+the Linux kernel targeted.
+
+@item -mkernel=@var{version}
+@opindex mkernel
+This specifies the minimum version of the kernel that will run the
+compiled program. GCC uses this version to determine which
+instructions to use, what kernel helpers to allow, etc. Currently,
+@var{version} can be one of @samp{4.0}, @samp{4.1}, @samp{4.2},
+@samp{4.3}, @samp{4.4}, @samp{4.5}, @samp{4.6}, @samp{4.7},
+@samp{4.8}, @samp{4.9}, @samp{4.10}, @samp{4.11}, @samp{4.12},
+@samp{4.13}, @samp{4.14}, @samp{4.15}, @samp{4.16}, @samp{4.17},
+@samp{4.18}, @samp{4.19}, @samp{4.20}, @samp{5.0}, @samp{5.1},
+@samp{5.2}, @samp{latest} and @samp{native}.
+
+@item -mbig-endian
+@opindex mbig-endian
+Generate code for a big-endian target.
+
+@item -mlittle-endian
+@opindex mlittle-endian
+Generate code for a little-endian target. This is the default.
+@end table
+
@node FR30 Options
@subsection FR30 Options
@cindex FR30 Options
command line defines the C preprocessor symbol @code{__XXX__} and
cause the linker to search for a script called @file{xxx.ld}.
-This option is also passed on to the assembler.
+The ISA and hardware multiply supported for the different MCUs is hard-coded
+into GCC. However, an external @samp{devices.csv} file can be used to
+extend device support beyond those that have been hard-coded.
+
+GCC searches for the @samp{devices.csv} file using the following methods in the
+given precedence order, where the first method takes precendence over the
+second which takes precedence over the third.
+
+@table @asis
+@item Include path specified with @code{-I} and @code{-L}
+@samp{devices.csv} will be searched for in each of the directories specified by
+include paths and linker library search paths.
+@item Path specified by the environment variable @samp{MSP430_GCC_INCLUDE_DIR}
+Define the value of the global environment variable
+@samp{MSP430_GCC_INCLUDE_DIR}
+to the full path to the directory containing devices.csv, and GCC will search
+this directory for devices.csv. If devices.csv is found, this directory will
+also be registered as an include path, and linker library path. Header files
+and linker scripts in this directory can therefore be used without manually
+specifying @code{-I} and @code{-L} on the command line.
+@item The @samp{msp430-elf/include/devices} directory
+Finally, GCC will examine @samp{msp430-elf/include/devices} from the
+toolchain root directory. This directory does not exist in a default
+installation, but if the user has created it and copied @samp{devices.csv}
+there, then the MCU data will be read. As above, this directory will
+also be registered as an include path, and linker library path.
+
+@end table
+If none of the above search methods find @samp{devices.csv}, then the
+hard-coded MCU data is used.
+
@item -mwarn-mcu
@itemx -mno-warn-mcu
devices. The compiler includes special symbols in some objects
that tell the linker and runtime which code fragments are required.
+@item -mtiny-printf
+@opindex mtiny-printf
+Enable reduced code size @code{printf} and @code{puts} library functions.
+The @samp{tiny} implementations of these functions are not reentrant, so
+must be used with caution in multi-threaded applications.
+
+Support for streams has been removed and the string to be printed will
+always be sent to stdout via the @code{write} syscall. The string is not
+buffered before it is sent to write.
+
+This option requires Newlib Nano IO, so GCC must be configured with
+@samp{--enable-newlib-nano-formatted-io}.
+
@item -mcode-region=
@itemx -mdata-region=
@opindex mcode-region
This option passes on a request to the assembler to enable warning
messages when a silicon errata might need to be applied.
+@item -mwarn-devices-csv
+@itemx -mno-warn-devices-csv
+@opindex mwarn-devices-csv
+@opindex mno-warn-devices-csv
+Warn if @samp{devices.csv} is not found or there are problem parsing it
+(default: on).
+
@end table
@node NDS32 Options
@item -mnewlib
@opindex mnewlib
-For compatibility, it's always newlib for elf now.
+This option is ignored; it is for compatibility purposes only. This used to
+select linker and preprocessor options for use with newlib.
-@item -mhard-div
+@item -msoft-div
+@itemx -mhard-div
+@opindex msoft-div
@opindex mhard-div
-Generate code for hardware which supports divide instructions. This is the
-default.
+Select software or hardware divide (@code{l.div}, @code{l.divu}) instructions.
+This default is hardware divide.
-@item -mhard-mul
+@item -msoft-mul
+@itemx -mhard-mul
+@opindex msoft-mul
@opindex mhard-mul
-Generate code for hardware which supports multiply instructions. This is the
-default.
+Select software or hardware multiply (@code{l.mul}, @code{l.muli}) instructions.
+This default is hardware multiply.
+
+@item -msoft-float
+@itemx -mhard-float
+@opindex msoft-float
+@opindex mhard-float
+Select software or hardware for floating point operations.
+The default is software.
+
+@item -mdouble-float
+@opindex mdouble-float
+When @option{-mhard-float} is selected, enables generation of double-precision
+floating point instructions. By default functions from @file{libgcc} are used
+to perform double-precision floating point operations.
+
+@item -munordered-float
+@opindex munordered-float
+When @option{-mhard-float} is selected, enables generation of unordered
+floating point compare and set flag (@code{lf.sfun*}) instructions. By default
+functions from @file{libgcc} are used to perform unordered floating point
+compare and set flag operations.
@item -mcmov
@opindex mcmov
-Generate code for hardware which supports the conditional move (@code{l.cmov})
-instruction.
+Enable generation of conditional move (@code{l.cmov}) instructions. By
+default the equivalent will be generated using using set and branch.
@item -mror
@opindex mror
-Generate code for hardware which supports rotate right instructions.
+Enable generation of rotate right (@code{l.ror}) instructions. By default
+functions from @file{libgcc} are used to perform rotate right operations.
+
+@item -mrori
+@opindex mrori
+Enable generation of rotate right with immediate (@code{l.rori}) instructions.
+By default functions from @file{libgcc} are used to perform rotate right with
+immediate operations.
@item -msext
@opindex msext
-Generate code for hardware which supports sign-extension instructions.
+Enable generation of sign extension (@code{l.ext*}) instructions. By default
+memory loads are used to perform sign extension.
@item -msfimm
@opindex msfimm
-Generate code for hardware which supports set flag immediate (@code{l.sf*i})
-instructions.
+Enable generation of compare and set flag with immediate (@code{l.sf*i})
+instructions. By default extra instructions will be generated to store the
+immediate to a register first.
@item -mshftimm
@opindex mshftimm
-Generate code for hardware which supports shift immediate related instructions
-(i.e. @code{l.srai}, @code{l.srli}, @code{l.slli}, @code{1.rori}). Note, to
-enable generation of the @code{l.rori} instruction the @option{-mror} flag must
-also be specified.
+Enable generation of shift with immediate (@code{l.srai}, @code{l.srli},
+@code{l.slli}) instructions. By default extra instructions will be generated
+to store the immediate to a register first.
-@item -msoft-div
-@opindex msoft-div
-Generate code for hardware which requires divide instruction emulation.
-
-@item -msoft-mul
-@opindex msoft-mul
-Generate code for hardware which requires multiply instruction emulation.
@end table
@itemx -mno-emit-attribute
Emit (do not emit) RISC-V attribute to record extra information into ELF
objects. This feature requires at least binutils 2.32.
+
+@item -malign-data=@var{type}
+@opindex malign-data
+Control how GCC aligns variables and constants of array, structure, or union
+types. Supported values for @var{type} are @samp{xlen} which uses x register
+width as the alignment value, and @samp{natural} which uses natural alignment.
+@samp{xlen} is the default.
@end table
@node RL78 Options
Otherwise, assume no such offset is present.
@end table
-@node SPU Options
-@subsection SPU Options
-@cindex SPU options
-
-These @samp{-m} options are supported on the SPU:
-
-@table @gcctabopt
-@item -mwarn-reloc
-@itemx -merror-reloc
-@opindex mwarn-reloc
-@opindex merror-reloc
-
-The loader for SPU does not handle dynamic relocations. By default, GCC
-gives an error when it generates code that requires a dynamic
-relocation. @option{-mno-error-reloc} disables the error,
-@option{-mwarn-reloc} generates a warning instead.
-
-@item -msafe-dma
-@itemx -munsafe-dma
-@opindex msafe-dma
-@opindex munsafe-dma
-
-Instructions that initiate or test completion of DMA must not be
-reordered with respect to loads and stores of the memory that is being
-accessed.
-With @option{-munsafe-dma} you must use the @code{volatile} keyword to protect
-memory accesses, but that can lead to inefficient code in places where the
-memory is known to not change. Rather than mark the memory as volatile,
-you can use @option{-msafe-dma} to tell the compiler to treat
-the DMA instructions as potentially affecting all memory.
-
-@item -mbranch-hints
-@opindex mbranch-hints
-
-By default, GCC generates a branch hint instruction to avoid
-pipeline stalls for always-taken or probably-taken branches. A hint
-is not generated closer than 8 instructions away from its branch.
-There is little reason to disable them, except for debugging purposes,
-or to make an object a little bit smaller.
-
-@item -msmall-mem
-@itemx -mlarge-mem
-@opindex msmall-mem
-@opindex mlarge-mem
-
-By default, GCC generates code assuming that addresses are never larger
-than 18 bits. With @option{-mlarge-mem} code is generated that assumes
-a full 32-bit address.
-
-@item -mstdmain
-@opindex mstdmain
-
-By default, GCC links against startup code that assumes the SPU-style
-main function interface (which has an unconventional parameter list).
-With @option{-mstdmain}, GCC links your program against startup
-code that assumes a C99-style interface to @code{main}, including a
-local copy of @code{argv} strings.
-
-@item -mfixed-range=@var{register-range}
-@opindex mfixed-range
-Generate code treating the given register range as fixed registers.
-A fixed register is one that the register allocator cannot use. This is
-useful when compiling kernel code. A register range is specified as
-two registers separated by a dash. Multiple register ranges can be
-specified separated by a comma.
-
-@item -mea32
-@itemx -mea64
-@opindex mea32
-@opindex mea64
-Compile code assuming that pointers to the PPU address space accessed
-via the @code{__ea} named address space qualifier are either 32 or 64
-bits wide. The default is 32 bits. As this is an ABI-changing option,
-all object code in an executable must be compiled with the same setting.
-
-@item -maddress-space-conversion
-@itemx -mno-address-space-conversion
-@opindex maddress-space-conversion
-@opindex mno-address-space-conversion
-Allow/disallow treating the @code{__ea} address space as superset
-of the generic address space. This enables explicit type casts
-between @code{__ea} and generic pointer as well as implicit
-conversions of generic pointers to @code{__ea} pointers. The
-default is to allow address space pointer conversions.
-
-@item -mcache-size=@var{cache-size}
-@opindex mcache-size
-This option controls the version of libgcc that the compiler links to an
-executable and selects a software-managed cache for accessing variables
-in the @code{__ea} address space with a particular cache size. Possible
-options for @var{cache-size} are @samp{8}, @samp{16}, @samp{32}, @samp{64}
-and @samp{128}. The default cache size is 64KB.
-
-@item -matomic-updates
-@itemx -mno-atomic-updates
-@opindex matomic-updates
-@opindex mno-atomic-updates
-This option controls the version of libgcc that the compiler links to an
-executable and selects whether atomic updates to the software-managed
-cache of PPU-side variables are used. If you use atomic updates, changes
-to a PPU variable from SPU code using the @code{__ea} named address space
-qualifier do not interfere with changes to other PPU variables residing
-in the same cache line from PPU code. If you do not use atomic updates,
-such interference may occur; however, writing back cache lines is
-more efficient. The default behavior is to use atomic updates.
-
-@item -mdual-nops
-@itemx -mdual-nops=@var{n}
-@opindex mdual-nops
-By default, GCC inserts NOPs to increase dual issue when it expects
-it to increase performance. @var{n} can be a value from 0 to 10. A
-smaller @var{n} inserts fewer NOPs. 10 is the default, 0 is the
-same as @option{-mno-dual-nops}. Disabled with @option{-Os}.
-
-@item -mhint-max-nops=@var{n}
-@opindex mhint-max-nops
-Maximum number of NOPs to insert for a branch hint. A branch hint must
-be at least 8 instructions away from the branch it is affecting. GCC
-inserts up to @var{n} NOPs to enforce this, otherwise it does not
-generate the branch hint.
-
-@item -mhint-max-distance=@var{n}
-@opindex mhint-max-distance
-The encoding of the branch hint instruction limits the hint to be within
-256 instructions of the branch it is affecting. By default, GCC makes
-sure it is within 125.
-
-@item -msafe-hints
-@opindex msafe-hints
-Work around a hardware bug that causes the SPU to stall indefinitely.
-By default, GCC inserts the @code{hbrp} instruction to make sure
-this stall won't happen.
-
-@end table
-
@node System V Options
@subsection Options for System V
BMI2, F16C, RDSEED, ADCX, PREFETCHW, CLFLUSHOPT, XSAVEC, XSAVES, AVX512F, CLWB,
AVX512VL, AVX512BW, AVX512DQ, AVX512CD and AVX512VNNI instruction set support.
+@item cooperlake
+Intel cooperlake 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, CLWB,
+AVX512VL, AVX512BW, AVX512DQ, AVX512CD, AVX512VNNI and AVX512BF16 instruction
+set support.
+
+@item tigerlake
+Intel Tigerlake 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, WBNOINVD, MOVDIRI, MOVDIR64B and AVX512VP2INTERSECT instruction
+set support.
+
@item k6
AMD K6 CPU with MMX instruction set support.
@itemx -mavx512vpopcntdq
@opindex mavx512vpopcntdq
@need 200
+@itemx -mavx512vp2intersect
+@opindex mavx512vp2intersect
+@need 200
@itemx -mavx5124fmaps
@opindex mavx5124fmaps
@need 200
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