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Diffstat (limited to 'gcc/doc/invoke.texi')
| -rw-r--r-- | gcc/doc/invoke.texi | 311 |
1 files changed, 215 insertions, 96 deletions
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index b1a0d93..14a78fd 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -211,8 +211,7 @@ in the following sections. @item C++ Language Options @xref{C++ Dialect Options,,Options Controlling C++ Dialect}. @gccoptlist{-fabi-version=@var{n} -fno-access-control --faligned-new=@var{n} -fargs-in-order=@var{n} --fno-assume-sane-operators-new-delete +-faligned-new=@var{n} -fno-assume-sane-operators-new-delete -fchar8_t -fcheck-new -fconcepts -fconstexpr-depth=@var{n} -fconstexpr-cache-depth=@var{n} -fconstexpr-loop-limit=@var{n} -fconstexpr-ops-limit=@var{n} @@ -235,6 +234,7 @@ in the following sections. -fno-optional-diags -fno-pretty-templates -frange-for-ext-temps -fno-rtti -fsized-deallocation +-fstrong-eval-order@r{[}=@var{kind}@r{]} -ftemplate-backtrace-limit=@var{n} -ftemplate-depth=@var{n} -fno-threadsafe-statics -fuse-cxa-atexit @@ -394,7 +394,8 @@ Objective-C and Objective-C++ Dialects}. -Wmemset-elt-size -Wmemset-transposed-args -Wmisleading-indentation -Wmissing-attributes -Wmissing-braces -Wmissing-field-initializers -Wmissing-format-attribute --Wmissing-include-dirs -Wmissing-noreturn -Wno-missing-profile +-Wmissing-include-dirs -Wmissing-noreturn -Wmusttail-local-addr +-Wmaybe-musttail-local-addr -Wno-missing-profile -Wno-multichar -Wmultistatement-macros -Wnonnull -Wnonnull-compare -Wnormalized=@r{[}none@r{|}id@r{|}nfc@r{|}nfkc@r{]} -Wnull-dereference -Wno-odr @@ -405,7 +406,9 @@ Objective-C and Objective-C++ Dialects}. -Wparentheses -Wno-pedantic-ms-format -Wpointer-arith -Wno-pointer-compare -Wno-pointer-to-int-cast -Wno-pragmas -Wno-pragma-once-outside-header -Wno-prio-ctor-dtor --Wredundant-decls -Wrestrict -Wno-return-local-addr -Wreturn-type +-Wno-psabi +-Wredundant-decls -Wrestrict +-Wno-return-local-addr -Wreturn-type -Wno-scalar-storage-order -Wsequence-point -Wshadow -Wshadow=global -Wshadow=local -Wshadow=compatible-local -Wno-shadow-ivar @@ -590,7 +593,7 @@ Objective-C and Objective-C++ Dialects}. -finline-functions -finline-functions-called-once -finline-limit=@var{n} -finline-small-functions -fipa-modref -fipa-cp -fipa-cp-clone -fipa-bit-cp -fipa-vrp -fipa-pta -fipa-profile -fipa-pure-const --fipa-reference -fipa-reference-addressable +-fipa-reference -fipa-reference-addressable -fipa-reorder-for-locality -fipa-stack-alignment -fipa-icf -fira-algorithm=@var{algorithm} -flate-combine-instructions -flifetime-dse -flive-patching=@var{level} -fira-region=@var{region} -fira-hoist-pressure @@ -639,8 +642,8 @@ Objective-C and Objective-C++ Dialects}. -fsplit-wide-types -fsplit-wide-types-early -fssa-backprop -fssa-phiopt -fstdarg-opt -fstore-merging -fstrict-aliasing -fipa-strict-aliasing -fthread-jumps -ftracer -ftree-bit-ccp --ftree-builtin-call-dce -ftree-ccp -ftree-ch --ftree-coalesce-vars -ftree-copy-prop -ftree-dce -ftree-dominator-opts +-ftree-builtin-call-dce -ftree-ccp -ftree-ch -ftree-coalesce-vars +-ftree-copy-prop -ftree-cselim -ftree-dce -ftree-dominator-opts -ftree-dse -ftree-forwprop -ftree-fre -fcode-hoisting -ftree-loop-if-convert -ftree-loop-im -ftree-phiprop -ftree-loop-distribution -ftree-loop-distribute-patterns @@ -672,7 +675,7 @@ Objective-C and Objective-C++ Dialects}. -fsanitize=@var{style} -fsanitize-recover -fsanitize-recover=@var{style} -fsanitize-trap -fsanitize-trap=@var{style} -fasan-shadow-offset=@var{number} -fsanitize-sections=@var{s1},@var{s2},... --fsanitize-undefined-trap-on-error -fbounds-check +-fsanitize-undefined-trap-on-error -fbounds-check -fcf-protection -fcf-protection=@r{[}full@r{|}branch@r{|}return@r{|}none@r{|}check@r{]} -fharden-compares -fharden-conditional-branches -fhardened -fharden-control-flow-redundancy -fhardcfr-skip-leaf @@ -2196,6 +2199,7 @@ those that have already been displayed. If @option{--help} is also specified anywhere on the command line then this takes precedence over any @option{--help=} option. +@opindex Q If the @option{-Q} option appears on the command line before the @option{--help=} option, then the descriptive text displayed by @option{--help=} is changed. Instead of describing the displayed @@ -3578,12 +3582,19 @@ type. @opindex fstrong-eval-order @item -fstrong-eval-order +@itemx -fstrong-eval-order=@var{kind} Evaluate member access, array subscripting, and shift expressions in left-to-right order, and evaluate assignment in right-to-left order, -as adopted for C++17. Enabled by default with @option{-std=c++17}. +as adopted for C++17. @option{-fstrong-eval-order} is equivalent to +@option{-fstrong-eval-order=all}, +and is enabled by default with @option{-std=c++17} or later. + @option{-fstrong-eval-order=some} enables just the ordering of member -access and shift expressions, and is the default without -@option{-std=c++17}. +access and shift expressions, and is the default for C++ dialects prior to +C++17. + +@option{-fstrong-eval-order=none} is equivalent to +@option{-fno-strong-eval-order}. @opindex ftemplate-backtrace-limit @item -ftemplate-backtrace-limit=@var{n} @@ -6144,12 +6155,12 @@ Inhibit all warning messages. @opindex Werror @opindex Wno-error @item -Werror -Make all warnings into errors. +Turn all warnings into errors. @opindex Werror= @opindex Wno-error= @item -Werror= -Make the specified warning into an error. The specifier for a warning +Turn the specified warning into an error. The specifier for a warning is appended; for example @option{-Werror=switch} turns the warnings controlled by @option{-Wswitch} into errors. This switch takes a negative form, to be used to negate @option{-Werror} for specific @@ -6177,10 +6188,11 @@ messages. @end table You can request many specific warnings with options beginning with -@samp{-W}, for example @option{-Wimplicit} to request warnings on -implicit declarations. Each of these specific warning options also -has a negative form beginning @samp{-Wno-} to turn off warnings; for -example, @option{-Wno-implicit}. This manual lists only one of the +@samp{-W}, for example @option{-Wunused-variable} to request warnings on +declarations of variables that are never used. +Each of these specific warning options also +has a negative form beginning with @samp{-Wno-} to turn off warnings; for +example, @option{-Wno-unused-variable}. This manual lists only one of the two forms, whichever is not the default. For further language-specific options also refer to @ref{C++ Dialect Options} and @ref{Objective-C and Objective-C++ Dialect Options}. @@ -6189,15 +6201,15 @@ Additional warnings can be produced by enabling the static analyzer; Some options, such as @option{-Wall} and @option{-Wextra}, turn on other options, such as @option{-Wunused}, which may turn on further options, -such as @option{-Wunused-value}. The combined effect of positive and +such as @option{-Wunused-variable}. The combined effect of positive and negative forms is that more specific options have priority over less -specific ones, independently of their position in the command-line. For +specific ones, independently of their position in the command line. For options of the same specificity, the last one takes effect. Options enabled or disabled via pragmas (@pxref{Diagnostic Pragmas}) take effect -as if they appeared at the end of the command-line. +as if they appeared at the end of the command line. When an unrecognized warning option is requested (e.g., -@option{-Wunknown-warning}), GCC emits a diagnostic stating +@option{-Wunknown-warning}), GCC gives an error stating that the option is not recognized. However, if the @option{-Wno-} form is used, the behavior is slightly different: no diagnostic is produced for @option{-Wno-unknown-warning} unless other diagnostics @@ -6206,11 +6218,11 @@ with old compilers, but if something goes wrong, the compiler warns that an unrecognized option is present. The effectiveness of some warnings depends on optimizations also being -enabled. For example @option{-Wsuggest-final-types} is more effective -with link-time optimization and some instances of other warnings may +enabled. For example, @option{-Wsuggest-final-types} is more effective +with link-time optimization. Some other warnings may not be issued at all unless optimization is enabled. While optimization -in general improves the efficacy of control and data flow sensitive -warnings, in some cases it may also cause false positives. +in general improves the efficacy of warnings about control and data-flow +problems, in some cases it may also cause false positives. @table @gcctabopt @opindex pedantic @@ -6496,7 +6508,8 @@ of a derived class. Warn about code affected by ABI changes. This includes code that may not be compatible with the vendor-neutral C++ ABI as well as the psABI -for the particular target. +for the particular target. The latter warnings are also controlled +separately by @option{-Wpsabi}, which is implied by @option{-Wabi}. Since G++ now defaults to updating the ABI with each major release, normally @option{-Wabi} warns only about C++ ABI compatibility @@ -6599,27 +6612,21 @@ This was fixed in @option{-fabi-version=10}, the default for GCC 6.1. @end itemize -This option also enables warnings about psABI-related changes. -The known psABI changes at this point include: +@opindex Wpsabi +@opindex Wno-psabi +@item -Wpsabi @r{(C, Objective-C, C++ and Objective-C++ only)} -@itemize @bullet - -@item -For SysV/x86-64, unions with @code{long double} members are -passed in memory as specified in psABI. Prior to GCC 4.4, this was not -the case. For example: +@option{-Wpsabi} enables warnings about processor-specific ABI +changes, such as changes in alignment requirements or how function +arguments are passed. On several targets, including AArch64, ARM, +x86, MIPS, RS6000/PowerPC, and S/390, these details have changed +between different versions of GCC and/or different versions of the C +or C++ language standards in ways that affect binary compatibility of +compiled code. With @option{-Wpsabi}, GCC can detect potentially +incompatible usages and warn you about them. -@smallexample -union U @{ - long double ld; - int i; -@}; -@end smallexample - -@noindent -@code{union U} is now always passed in memory. - -@end itemize +@option{-Wpsabi} is enabled by default, and is also implied by +@option{-Wabi}. @opindex Wchanges-meaning @opindex Wno-changes-meaning @@ -6972,6 +6979,55 @@ is only active when @option{-fdelete-null-pointer-checks} is active, which is enabled by optimizations in most targets. The precision of the warnings depends on the optimization options used. +@opindex Wno-musttail-local-addr +@opindex -Wmusttail-local-addr +@item -Wno-musttail-local-addr +Do not warn about passing a pointer (or in C++, a reference) to a +local variable or label to argument of a @code{musttail} call. Those +variables go out of scope before the tail call instruction. + +@opindex Wmaybe-musttail-local-addr +@opindex -Wno-maybe-musttail-local-addr +@item -Wmaybe-musttail-local-addr +Warn when address of a local variable can escape to a @code{musttail} +call, unless it goes out of scope already before the @code{musttail} +call. + +@smallexample +int foo (int *); + +int +bar (int *x) +@{ + if (x[0] == 1) + @{ + int a = 42; + foo (&a); + /* Without the @code{musttail} attribute this call would not + be tail called, because address of the @code{a} variable escapes + and the second foo call could dereference it. With the attribute + the local variables are assumed to go out of scope immediately + before the tail call instruction and the compiler warns about + this. */ + [[gnu::musttail]] return foo (nullptr); + @} + else + @{ + @{ + int a = 42; + foo (&a); + @} + /* The @code{a} variable isn't already in scope, so even when it + escaped, even without @code{musttail} attribute it would be + undefined behavior to dereference it and the compiler could + turn this into a tail call. No warning is diagnosed here. */ + [[gnu::musttail]] return foo (nullptr); + @} +@} +@end smallexample + +This warning is enabled by @option{-Wextra}. + @opindex Wnrvo @opindex Wno-nrvo @item -Wnrvo @r{(C++ and Objective-C++ only)} @@ -10062,8 +10118,9 @@ a warning.) @opindex Wno-aggressive-loop-optimizations @opindex Waggressive-loop-optimizations @item -Wno-aggressive-loop-optimizations -Warn if in a loop with constant number of iterations the compiler detects -undefined behavior in some statement during one or more of the iterations. +Do not warn if the compiler detects undefined behavior in a loop with +a constant number of iterations. @option{-Waggressive-loop-optimizations} +is enabled by default. @opindex Wno-attributes @opindex Wattributes @@ -12690,6 +12747,7 @@ complexity than at @option{-O}. -fipa-pure-const -fipa-reference -fipa-reference-addressable +-fivopts -fmerge-constants -fmove-loop-invariants -fmove-loop-stores @@ -12798,6 +12856,13 @@ by @option{-O2} and also turns on the following optimization flags: Reduce compilation time and make debugging produce the expected results. This is the default. +At @option{-O0}, GCC completely disables most optimization passes; +they are not run even if you explicitly enable them on the command +line, or are listed by @option{-Q --help=optimizers} as being enabled by +default. Many optimizations performed by GCC depend on code analysis +or canonicalization passes that are enabled by @option{-O}, and it would +not be useful to run individual optimization passes in isolation. + @opindex Os @item -Os Optimize for size. @option{-Os} enables all @option{-O2} optimizations @@ -13815,6 +13880,21 @@ Enabled by default at @option{-O1} and higher. Discover read-only, write-only and non-addressable static variables. Enabled by default at @option{-O1} and higher. +@opindex fipa-reorder-for-locality +@item -fipa-reorder-for-locality +Group call chains close together in the binary layout to improve code +locality and minimize jump distances between frequently called functions. +Unlike @option{-freorder-functions} this pass considers the call +chains between functions and groups them together, rather than grouping all +hot/normal/cold/never-executed functions into separate sections. +Unlike @option{-fprofile-reorder-functions} it aims to improve code locality +throughout the runtime of the program rather than focusing on program startup. +This option is incompatible with an explicit +@option{-flto-partition=} option since it enforces a custom partitioning +scheme. +If using this option it is recommended to also use profile feedback, but this +option is not enabled by default otherwise. + @opindex fipa-stack-alignment @item -fipa-stack-alignment Reduce stack alignment on call sites if possible. @@ -14023,6 +14103,12 @@ in this pass can be limited using @option{max-tail-merge-comparisons} parameter and @option{max-tail-merge-iterations} parameter. +@opindex ftree-cselim +@item -ftree-cselim +Perform conditional store elimination on trees. This flag is enabled by +default at @option{-O1} and higher on targets that have conditional +move instructions. + @opindex ftree-dce @item -ftree-dce Perform dead code elimination (DCE) on trees. This flag is enabled by @@ -14229,6 +14315,7 @@ Enabled by default at @option{-O1} and higher. @item -fivopts Perform induction variable optimizations (strength reduction, induction variable merging and induction variable elimination) on trees. +Enabled by default at @option{-O1} and higher. @opindex ftree-parallelize-loops @item -ftree-parallelize-loops=n @@ -14544,11 +14631,13 @@ Enabled for x86 at levels @option{-O2}, @option{-O3}, @option{-Os}. @opindex freorder-functions @item -freorder-functions Reorder functions in the object file in order to -improve code locality. This is implemented by using special -subsections @code{.text.hot} for most frequently executed functions and -@code{.text.unlikely} for unlikely executed functions. Reordering is done by -the linker so object file format must support named sections and linker must -place them in a reasonable way. +improve code locality. Unlike @option{-fipa-reorder-for-locality} this option +prioritises grouping all functions within a category +(hot/normal/cold/never-executed) together. +This is implemented by using special subsections @code{.text.hot} for most +frequently executed functions and @code{.text.unlikely} for unlikely executed +functions. Reordering is done by the linker so object file format must support +named sections and linker must place them in a reasonable way. This option isn't effective unless you either provide profile feedback (see @option{-fprofile-arcs} for details) or manually annotate functions with @@ -15269,32 +15358,24 @@ arithmetic. These options trade off between speed and correctness. All must be specifically enabled. @table @gcctabopt -@opindex ffloat-store -@item -ffloat-store -Do not store floating-point variables in registers, and inhibit other -options that might change whether a floating-point value is taken from a -register or memory. - -@cindex floating-point precision -This option prevents undesirable excess precision on machines such as -the 68000 where the floating registers (of the 68881) keep more -precision than a @code{double} is supposed to have. Similarly for the -x86 architecture. For most programs, the excess precision does only -good, but a few programs rely on the precise definition of IEEE floating -point. Use @option{-ffloat-store} for such programs, after modifying -them to store all pertinent intermediate computations into variables. - @opindex fexcess-precision @item -fexcess-precision=@var{style} -This option allows further control over excess precision on machines +This option allows control over excess precision on machines where floating-point operations occur in a format with more precision or -range than the IEEE standard and interchange floating-point types. By -default, @option{-fexcess-precision=fast} is in effect; this means that +range than the IEEE standard and interchange floating-point types. +An example of such a target is x87 floating point on x86 processors, +which uses an 80-bit representation internally instead of the 64-bit +IEEE format. For most programs, the excess precision is harmless, +but some programs may rely on the +requirements of the C or C++ language standards for handling IEEE values. + +By default, @option{-fexcess-precision=fast} is in effect; this means that operations may be carried out in a wider precision than the types specified in the source if that would result in faster code, and it is unpredictable when rounding to the types specified in the source code takes place. When compiling C or C++, if @option{-fexcess-precision=standard} is specified -then excess precision follows the rules specified in ISO C99 or C++; in particular, +then excess precision follows the rules specified in ISO C99 or C++; +in particular, both casts and assignments cause values to be rounded to their semantic types (whereas @option{-ffloat-store} only affects assignments). This option is enabled by default for C or C++ if a strict @@ -15312,6 +15393,18 @@ or @option{-mfpmath=sse+387} is specified; in the former case, IEEE semantics apply without excess precision, and in the latter, rounding is unpredictable. +@opindex ffloat-store +@item -ffloat-store +Do not store floating-point variables in registers, and inhibit other +options that might change whether a floating-point value is taken from a +register or memory. This option has generally been subsumed by +@option{-fexcess-precision=standard}, which is more general. If you do use +@option{-ffloat-store}, you may need to modify your program to explicitly +store intermediate computations in temporary variables since +@option{-ffloat-store} handles rounding to IEEE format +only on assignments and not casts as @option{-fexcess-precision=standard} +does. + @opindex ffast-math @item -ffast-math Sets the options @option{-fno-math-errno}, @option{-funsafe-math-optimizations}, @@ -15446,9 +15539,8 @@ default state for @code{FENV_ACCESS}. @opindex frounding-math @item -frounding-math Disable transformations and optimizations that assume default floating-point -rounding behavior. This is round-to-zero for all floating point -to integer conversions, and round-to-nearest for all other arithmetic -truncations. This option should be specified for programs that change +rounding behavior (round-to-nearest). +This option should be specified for programs that change the FP rounding mode dynamically, or that may be executed with a non-default rounding mode. This option disables constant folding of floating-point expressions at compile time (which may be affected by @@ -15570,7 +15662,8 @@ Enabled by @option{-fprofile-generate}, @option{-fprofile-use}, and @item -fprofile-reorder-functions Function reordering based on profile instrumentation collects first time of execution of a function and orders these functions -in ascending order. +in ascending order, aiming to optimize program startup through more +efficient loading of text segments. Enabled with @option{-fprofile-use}. @@ -16468,6 +16561,15 @@ in combiner for a pseudo register as last known value of that register. @item max-combine-insns The maximum number of instructions the RTL combiner tries to combine. +@item max-combine-search-insns +The maximum number of instructions that the RTL combiner searches in order +to find the next use of a given register definition. If this limit is reached +without finding such a use, the combiner will stop trying to optimize the +definition. + +Currently this limit only applies after certain successful combination +attempts, but it could be extended to other cases in future. + @item integer-share-limit Small integer constants can use a shared data structure, reducing the compiler's memory usage and increasing its speed. This sets the maximum @@ -18323,7 +18425,8 @@ operand constant, @code{__sanitizer_cov_trace_cmpf} or @opindex fcf-protection @item -fcf-protection=@r{[}full@r{|}branch@r{|}return@r{|}none@r{|}check@r{]} -Enable code instrumentation of control-flow transfers to increase +@itemx -fcf-protection +Enable code instrumentation to increase program security by checking that target addresses of control-flow transfer instructions (such as indirect function call, function return, indirect jump) are valid. This prevents diverting the flow of control @@ -18331,22 +18434,30 @@ to an unexpected target. This is intended to protect against such threats as Return-oriented Programming (ROP), and similarly call/jmp-oriented programming (COP/JOP). +The @option{-fcf-protection=} keywords are interpreted as follows. + The value @code{branch} tells the compiler to implement checking of validity of control-flow transfer at the point of indirect branch -instructions, i.e.@: call/jmp instructions. The value @code{return} -implements checking of validity at the point of returning from a -function. The value @code{full} is an alias for specifying both -@code{branch} and @code{return}. The value @code{none} turns off -instrumentation. +instructions, i.e.@: call/jmp instructions. + +The value @code{return} implements checking of validity at the point of +returning from a function. -To override @option{-fcf-protection}, @option{-fcf-protection=none} -needs to be added and then with @option{-fcf-protection=xxx}. +The value @code{full} is an alias for specifying both +@code{branch} and @code{return}. The value @code{check} is used for the final link with link-time optimization (LTO). An error is issued if LTO object files are compiled with different @option{-fcf-protection} values. The value @code{check} is ignored at the compile time. +The value @code{none} turns off instrumentation. + +@option{-fcf-protection} is an alias for @option{-fcf-protection=full}. +To override a previous @option{-fcf-protection} option on the command +line, add @option{-fcf-protection=none} and then +@option{-fcf-protection=@var{kind}}. + 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 @@ -21201,8 +21312,13 @@ Toggle @option{-fvar-tracking-assignments}, in the same way that @opindex Q @item -Q -Makes the compiler print out each function name as it is compiled, and -print some statistics about each pass when it finishes. +When used on the command line prior to @option{--help=}, @option{-Q} +acts as a modifier to the help output. @xref{Overall Options}, +for details about @option{--help=}. + +Otherwise, this option makes the compiler print out each function name +as it is compiled, and print some statistics about each pass when it +finishes. @opindex ftime-report @item -ftime-report @@ -21802,11 +21918,13 @@ performance of the code. Permissible values for this option are: @samp{cortex-x2}, @samp{cortex-x3}, @samp{cortex-x4}, @samp{cortex-a510}, @samp{cortex-a520}, @samp{cortex-a520ae}, @samp{cortex-a710}, @samp{cortex-a715}, @samp{cortex-a720}, @samp{cortex-a720ae}, @samp{ampere1}, @samp{ampere1a}, -@samp{ampere1b}, @samp{cobalt-100} and @samp{native}. +@samp{ampere1b}, @samp{cobalt-100}, @samp{apple-m1}, @samp{apple-m2}, +@samp{apple-m3} and @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}, @samp{cortex-a76.cortex-a55} specify that GCC +@samp{cortex-a75.cortex-a55}, @samp{cortex-a76.cortex-a55}, +@samp{apple-m1}, @samp{apple-m2}, @samp{apple-m3} specify that GCC should tune for a big.LITTLE system. The value @samp{neoverse-512tvb} specifies that GCC should tune @@ -32393,18 +32511,18 @@ and for AIX: @samp{vec-extabi}, @samp{vec-default}@. 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. Requires @option{-mlong-double-128} -to be enabled. +from IEEE extended-precision, the compiler issues a warning unless +you use the @option{-Wno-psabi} option (@pxref{Warning Options}). +Requires @option{-mlong-double-128} to be enabled. @opindex mabi=ieeelongdouble @item -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. Requires @option{-mlong-double-128} -to be enabled. +from IBM extended-precision, the compiler issues a warning unless +you use the @option{-Wno-psabi} option (@pxref{Warning Options}). +Requires @option{-mlong-double-128} to be enabled. @opindex mabi=elfv1 @item -mabi=elfv1 @@ -33259,7 +33377,7 @@ system representing a certain processor type. Possible values for @samp{z9-109}, @samp{z9-ec}/@samp{arch7}, @samp{z10}/@samp{arch8}, @samp{z196}/@samp{arch9}, @samp{zEC12}, @samp{z13}/@samp{arch11}, @samp{z14}/@samp{arch12}, @samp{z15}/@samp{arch13}, -@samp{z16}/@samp{arch14}, and @samp{native}. +@samp{z16}/@samp{arch14}, @samp{z17}/@samp{arch15}, and @samp{native}. The default is @option{-march=z900}. @@ -34753,7 +34871,8 @@ 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. +A generic CPU with 64-bit extensions, MMX, SSE, SSE2, and FXSR instruction set +support. @item x86-64-v2 @itemx x86-64-v3 @@ -34786,7 +34905,7 @@ Intel Lakemont MCU, based on Intel Pentium CPU. Intel Pentium MMX CPU, based on Pentium core with MMX instruction set support. @item pentiumpro -Intel Pentium Pro CPU@. +Intel Pentium Pro CPU with no MMX support. @item i686 When used with @option{-march}, the Pentium Pro |