diff options
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/cfg.texi | 10 | ||||
| -rw-r--r-- | gcc/doc/extend.texi | 121 | ||||
| -rw-r--r-- | gcc/doc/gm2.texi | 8 | ||||
| -rw-r--r-- | gcc/doc/install.texi | 6 | ||||
| -rw-r--r-- | gcc/doc/invoke.texi | 146 |
5 files changed, 144 insertions, 147 deletions
diff --git a/gcc/doc/cfg.texi b/gcc/doc/cfg.texi index b8c6427..bbd6694 100644 --- a/gcc/doc/cfg.texi +++ b/gcc/doc/cfg.texi @@ -297,10 +297,12 @@ edge. The opposite conversion is difficult, but should not happen anyway. The edges can be eliminated via @code{purge_dead_edges} call. @findex REG_EH_REGION, EDGE_ABNORMAL_CALL -In the RTL representation, the destination of an exception edge is -specified by @code{REG_EH_REGION} note attached to the insn. -In case of a trapping call the @code{EDGE_ABNORMAL_CALL} flag is set -too. In the @code{GIMPLE} representation, this extra flag is not set. +In the RTL representation, a @code{REG_EH_REGION} note is attached to +an instruction that can throw an exception. The destination of the +exception edge originating at such an instruction is specified by the +value of the @code{REG_EH_REGION} note. In case of a trapping call +the @code{EDGE_ABNORMAL_CALL} flag is set too. In the @code{GIMPLE} +representation, this extra flag is not set. @findex may_trap_p, tree_could_trap_p In the RTL representation, the predicate @code{may_trap_p} may be used diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index ae3357f..0978c4c 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -1933,6 +1933,13 @@ Note that if such a function is called indirectly the compiler may or may not inline it depending on optimization level and a failure to inline an indirect call may or may not be diagnosed. +If you need to use the inlined function in multiple translation units, +you should put the @code{always_inline} attribute on a function +definition in a header file that is included in all translation units +where the function is used. Link-time optimization can inline +functions across translation units, but only if an optimization level +that normally enables inlining is additionally specified. + @cindex @code{artificial} function attribute @item artificial This attribute is useful for small inline wrappers that if possible @@ -12299,15 +12306,6 @@ for the @samp{att} and @samp{intel} dialects of assembler: @item @code{%3} @tab @code{$.L3} @tab @code{OFFSET FLAT:.L3} -@item @code{%4} -@tab @code{$8} -@tab @code{8} -@item @code{%5} -@tab @code{%xmm0} -@tab @code{xmm0} -@item @code{%7} -@tab @code{$0} -@tab @code{0} @end multitable The table below shows the list of supported modifiers and their effects. @@ -12324,32 +12322,17 @@ The table below shows the list of supported modifiers and their effects. @tab @code{%b0} @tab @code{%al} @tab @code{al} -@item @code{B} -@tab print the opcode suffix of b. -@tab @code{%B0} -@tab @code{b} -@tab @item @code{c} @tab Require a constant operand and print the constant expression with no punctuation. @tab @code{%c1} @tab @code{2} @tab @code{2} -@item @code{d} -@tab print duplicated register operand for AVX instruction. -@tab @code{%d5} -@tab @code{%xmm0, %xmm0} -@tab @code{xmm0, xmm0} @item @code{E} @tab Print the address in Double Integer (DImode) mode (8 bytes) when the target is 64-bit. Otherwise mode is unspecified (VOIDmode). @tab @code{%E1} @tab @code{%(rax)} @tab @code{[rax]} -@item @code{g} -@tab Print the V16SFmode name of the register. -@tab @code{%g0} -@tab @code{%zmm0} -@tab @code{zmm0} @item @code{h} @tab Print the QImode name for a ``high'' register. @tab @code{%h0} @@ -12371,16 +12354,6 @@ high 8 bytes of SSE values. For a memref in (%rax), it generates @tab @code{%l3} @tab @code{.L3} @tab @code{.L3} -@item @code{L} -@tab print the opcode suffix of l. -@tab @code{%L0} -@tab @code{l} -@tab -@item @code{N} -@tab print maskz. -@tab @code{%N7} -@tab @code{@{z@}} -@tab @code{@{z@}} @item @code{p} @tab Print raw symbol name (without syntax-specific prefixes). @tab @code{%p2} @@ -12396,76 +12369,20 @@ issue the bare constant. See @code{p} above. @tab @code{%q0} @tab @code{%rax} @tab @code{rax} -@item @code{Q} -@tab print the opcode suffix of q. -@tab @code{%Q0} -@tab @code{q} -@tab -@item @code{R} -@tab print embedded rounding and sae. -@tab @code{%R4} -@tab @code{@{rn-sae@}, } -@tab @code{, @{rn-sae@}} -@item @code{r} -@tab print only sae. -@tab @code{%r4} -@tab @code{@{sae@}, } -@tab @code{, @{sae@}} -@item @code{s} -@tab print a shift double count, followed by the assemblers argument -delimiterprint the opcode suffix of s. -@tab @code{%s1} -@tab @code{$2, } -@tab @code{2, } -@item @code{S} -@tab print the opcode suffix of s. -@tab @code{%S0} -@tab @code{s} -@tab -@item @code{t} -@tab print the V8SFmode name of the register. -@tab @code{%t5} -@tab @code{%ymm0} -@tab @code{ymm0} -@item @code{T} -@tab print the opcode suffix of t. -@tab @code{%T0} -@tab @code{t} -@tab -@item @code{V} -@tab print naked full integer register name without %. -@tab @code{%V0} -@tab @code{eax} -@tab @code{eax} @item @code{w} @tab Print the HImode name of the register. @tab @code{%w0} @tab @code{%ax} @tab @code{ax} -@item @code{W} -@tab print the opcode suffix of w. -@tab @code{%W0} -@tab @code{w} -@tab -@item @code{x} -@tab print the V4SFmode name of the register. -@tab @code{%x5} -@tab @code{%xmm0} -@tab @code{xmm0} -@item @code{y} -@tab print "st(0)" instead of "st" as a register. -@tab @code{%y6} -@tab @code{%st(0)} -@tab @code{st(0)} @item @code{z} @tab Print the opcode suffix for the size of the current integer operand (one of @code{b}/@code{w}/@code{l}/@code{q}). @tab @code{%z0} @tab @code{l} @tab -@item @code{Z} -@tab Like @code{z}, with special suffixes for x87 instructions. @end multitable +@code{V} is a special modifier which prints the name of the full integer +register without @code{%}. @anchor{x86floatingpointasmoperands} @subsubsection x86 Floating-Point @code{asm} Operands @@ -13061,6 +12978,7 @@ C and/or C++ standards, while others remain specific to GNU C. * Binary constants:: Binary constants using the @samp{0b} prefix. * Dollar Signs:: Dollar sign is allowed in identifiers. * Character Escapes:: @samp{\e} stands for the character @key{ESC}. +* Raw String Literals:: C++ raw string literals are supported in C. * Alternate Keywords:: @code{__const__}, @code{__asm__}, etc., for header files. * Function Names:: Printable strings which are the name of the current function. @@ -14082,6 +14000,25 @@ machines, typically because the target assembler does not allow them. You can use the sequence @samp{\e} in a string or character constant to stand for the ASCII character @key{ESC}. +@node Raw String Literals +@subsection Raw String Literals +@cindex raw string literals +@cindex string literals, raw + +The C++11 standard added syntax for raw string literals prefixed +with @samp{R}. This syntax allows you to use an arbitrary delimiter +sequence instead of escaping special characters within the string. +For example, these string constants are all equivalent: + +@smallexample +const char *s1 = "\\"; +const char *s2 = R"(\)"; +const char *s3 = R"foo(\)foo"; +@end smallexample + +As an extension, GCC also accepts raw string literals in C with +@option{-std=gnu99} or later. + @node Alternate Keywords @subsection Alternate Keywords @cindex alternate keywords diff --git a/gcc/doc/gm2.texi b/gcc/doc/gm2.texi index 8baee24..cb52e8c 100644 --- a/gcc/doc/gm2.texi +++ b/gcc/doc/gm2.texi @@ -2699,10 +2699,10 @@ PROCEDURE Example (foo, bar: CARDINAL) : CARDINAL ; VAR myout: CARDINAL ; BEGIN - ASM VOLATILE ("movq %1,%%rax; addq %2,%%rax; movq %%rax,%0" + ASM VOLATILE ("movl %1,%%eax; addl %2,%%eax; movl %%eax,%0" : "=rm" (myout) (* outputs *) : "rm" (foo), "rm" (bar) (* inputs *) - : "rax") ; (* we trash *) + : "eax") ; (* we trash *) RETURN( myout ) END Example ; @end example @@ -2720,10 +2720,10 @@ VAR myout: CARDINAL ; BEGIN ASM VOLATILE ( - "movq %[left],%%rax; addq %[right],%%rax; movq %%rax,%[output]" + "movl %[left],%%eax; addl %[right],%%eax; movl %%eax,%[output]" : [output] "=rm" (myout) (* outputs *) : [left] "rm" (foo), [right] "rm" (bar) (* inputs *) - : "rax") ; (* we trash *) + : "eax") ; (* we trash *) RETURN( myout ) END Example ; @end example diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi index b5509ff..1af0082 100644 --- a/gcc/doc/install.texi +++ b/gcc/doc/install.texi @@ -350,6 +350,12 @@ documentation including the target @code{SYSTEM} definition module. If Python3 is unavailable Modula-2 documentation will include a target independent version of the SYSTEM modules. +@item @anchor{gccrs-prerequisite}gccrs + +The official Rust compiler and Rust build system (cargo) are required for +building various parts of the gccrs frontend, until gccrs can compile them +by itself. The minimum supported Rust version is 1.49. + @item A ``working'' POSIX compatible shell, or GNU bash Necessary when running @command{configure} because some diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index a040d65..020442a 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 @@ -593,7 +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 @@ -642,8 +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 @@ -2199,6 +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 @@ -3581,12 +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} @@ -12739,6 +12747,7 @@ complexity than at @option{-O}. -fipa-pure-const -fipa-reference -fipa-reference-addressable +-fivopts -fmerge-constants -fmove-loop-invariants -fmove-loop-stores @@ -12847,6 +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 @@ -13864,6 +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. @@ -14072,6 +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 @@ -14278,6 +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 @@ -14593,11 +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 @@ -14609,12 +14649,14 @@ Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}. @item -fstrict-aliasing Allow the compiler to assume the strictest aliasing rules applicable to the language being compiled. For C (and C++), this activates -optimizations based on the type of expressions. In particular, an -object of one type is assumed never to reside at the same address as an -object of a different type, unless the types are almost the same. For -example, an @code{unsigned int} can alias an @code{int}, but not a -@code{void*} or a @code{double}. A character type may alias any other -type. +optimizations based on the type of expressions. In particular, accessing +an object of one type via an expression of a different type is not allowed, +unless the types are @dfn{compatible types}, differ only in signedness or +qualifiers, or the expression has a character type. Accessing scalar +objects via a corresponding vector type is also allowed. + +For example, an @code{unsigned int} can alias an @code{int}, but not a +@code{void*} or a @code{double}. A character type may alias any other type. @anchor{Type-punning}Pay special attention to code like this: @smallexample @@ -15318,32 +15360,24 @@ 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 @@ -15361,6 +15395,18 @@ 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}, @@ -15495,9 +15541,8 @@ 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 @@ -15619,7 +15664,8 @@ 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}. @@ -21268,8 +21314,13 @@ 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 @@ -33328,7 +33379,7 @@ 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}. @@ -34822,7 +34873,8 @@ 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 @@ -34855,7 +34907,7 @@ 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 |