extend.texi, [...]: Move documentation of builtin versions of C library functions to one place and...
* extend.texi, invoke.texi: Move documentation of builtin versions of C library functions to one place and update. From-SVN: r37355
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Joseph Myers
Joseph Myers
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@ -1,3 +1,8 @@
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2000-11-10 Joseph S. Myers <jsm28@cam.ac.uk>
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* extend.texi, invoke.texi: Move documentation of builtin versions
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of C library functions to one place and update.
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2000-11-09 Richard Henderson <rth@redhat.com>
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* fold-const.c (fold): Compare TYPE_MAIN_VARIANT rather than
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@ -3225,6 +3225,47 @@ function as well.
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@node Other Builtins
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@section Other built-in functions provided by GNU CC
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@cindex builtin functions
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@findex __builtin_isgreater
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@findex __builtin_isgreaterequal
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@findex __builtin_isless
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@findex __builtin_islessequal
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@findex __builtin_islessgreater
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@findex __builtin_isunordered
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@findex abort
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@findex abs
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@findex alloca
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@findex bcmp
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@findex bzero
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@findex cos
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@findex cosf
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@findex cosl
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@findex exit
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@findex _exit
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@findex fabs
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@findex fabsf
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@findex fabsl
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@findex ffs
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@findex fputs
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@findex labs
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@findex llabs
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@findex memcmp
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@findex memcpy
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@findex memset
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@findex printf
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@findex sin
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@findex sinf
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@findex sinl
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@findex sqrt
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@findex sqrtf
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@findex sqrtl
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@findex strchr
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@findex strcmp
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@findex strcpy
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@findex strlen
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@findex strpbrk
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@findex strrchr
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@findex strstr
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GNU CC provides a large number of built-in functions other than the ones
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mentioned above. Some of these are for internal use in the processing
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@ -3235,15 +3276,47 @@ recommend general use of these functions.
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The remaining functions are provided for optimization purposes.
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GNU CC includes builtin versions of many of the functions in the
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standard C library. These will always be treated as having the same
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meaning as the C library function even if you specify the
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@samp{-fno-builtin} (@pxref{C Dialect Options}) option. These functions
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correspond to the C library functions @code{abort}, @code{abs},
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@code{alloca}, @code{cos}, @code{cosf}, @code{cosl}, @code{exit},
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@code{_exit}, @code{fabs}, @code{fabsf}, @code{fabsl}, @code{ffs},
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@code{labs}, @code{memcmp}, @code{memcpy}, @code{memset}, @code{sin},
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@code{sinf}, @code{sinl}, @code{sqrt}, @code{sqrtf}, @code{sqrtl},
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@code{strcmp}, @code{strcpy}, and @code{strlen}.
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standard C library. The versions prefixed with @code{__builtin_} will
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always be treated as having the same meaning as the C library function
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even if you specify the @samp{-fno-builtin} (@pxref{C Dialect Options})
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option. Many of these functions are only optimized in certain cases; if
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not optimized in a particular case, a call to the library function will
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be emitted.
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The functions @code{abort}, @code{exit}, and @code{_exit} are recognized
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and presumed not to return, but otherwise are not built in.
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@code{_exit} is not recognized in strict ISO C mode (@samp{-ansi},
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@samp{-std=c89} or @samp{-std=c99}).
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Outside strict ISO C mode, the functions @code{alloca}, @code{bcmp},
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@code{bzero}, and @code{ffs} may be handled as builtins. Corresponding
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versions @code{__builtin_alloca}, @code{__builtin_bcmp},
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@code{__builtin_bzero}, and @code{__builtin_ffs} are also recognized in
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strict ISO C mode.
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The ISO C99 function @code{llabs} is handled as a builtin except in
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strict ISO C89 mode. There are also builtin versions of the ISO C99
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functions @code{cosf}, @code{cosl}, @code{fabsf}, @code{fabsl},
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@code{sinf}, @code{sinl}, @code{sqrtf}, and @code{sqrtl}, that are
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recognized in any mode since ISO C89 reserves these names for the
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purpose to which ISO C99 puts them. All these functions have
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corresponding versions prefixed with @code{__builtin_}.
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The following ISO C89 functions are recognized as builtins unless
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@samp{-fno-builtin} is specified: @code{abs}, @code{cos}, @code{fabs},
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@code{fputs}, @code{labs}, @code{memcmp}, @code{memcpy}, @code{memset},
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@code{printf}, @code{sin}, @code{sqrt}, @code{strchr}, @code{strcmp},
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@code{strcpy}, @code{strlen}, @code{strpbrk}, @code{strrchr}, and
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@code{strstr}. All of these functions have corresponding versions
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prefixed with @code{__builtin_}, except that the version for @code{sqrt}
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is called @code{__builtin_fsqrt}.
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GNU CC provides builtin versions of the ISO C99 floating point
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comparison macros (that avoid raising exceptions for unordered
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operands): @code{__builtin_isgreater}, @code{__builtin_isgreaterequal},
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@code{__builtin_isless}, @code{__builtin_islessequal},
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@code{__builtin_islessgreater}, and @code{__builtin_isunordered}.
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@table @code
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@findex __builtin_constant_p
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@ -727,8 +727,11 @@ from declaring certain functions or defining certain macros that the
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ANSI standard doesn't call for; this is to avoid interfering with any
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programs that might use these names for other things.
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The functions @code{alloca}, @code{abort}, @code{exit}, and
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@code{_exit} are not builtin functions when @samp{-ansi} is used.
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Functions which would normally be builtin but do not have semantics
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defined by ISO C (such as @code{alloca} and @code{ffs}) are not builtin
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functions with @samp{-ansi} is used. @xref{Other Builtins,,Other
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built-in functions provided by GNU CC}, for details of the functions
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affected.
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@item -std=
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Determine the language standard. A value for this option must be provided;
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@ -785,38 +788,11 @@ use the @samp{-fno-gnu-keywords} flag instead, which has the same effect.
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@item -fno-builtin
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@cindex builtin functions
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@findex abort
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@findex abs
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@findex alloca
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@findex cos
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@findex cosf
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@findex cosl
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@findex exit
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@findex _exit
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@findex fabs
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@findex fabsf
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@findex fabsl
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@findex ffs
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@findex labs
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@findex memcmp
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@findex memcpy
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@findex memset
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@findex sin
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@findex sinf
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@findex sinl
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@findex sqrt
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@findex sqrtf
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@findex sqrtl
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@findex strcmp
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@findex strcpy
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@findex strlen
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Don't recognize builtin functions that do not begin with @samp{__builtin_}
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as prefix. Currently, the functions affected include @code{abort},
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@code{abs}, @code{alloca}, @code{cos}, @code{cosf}, @code{cosl},
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@code{exit}, @code{_exit}, @code{fabs}, @code{fabsf}, @code{fabsl},
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@code{ffs}, @code{labs}, @code{memcmp}, @code{memcpy}, @code{memset},
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@code{sin}, @code{sinf}, @code{sinl}, @code{sqrt}, @code{sqrtf},
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@code{sqrtl}, @code{strcmp}, @code{strcpy}, and @code{strlen}.
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Don't recognize builtin functions that do not begin with
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@samp{__builtin_} as prefix. @xref{Other Builtins,,Other built-in
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functions provided by GNU CC}, for details of the functions affected,
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including those which are not builtin functions when @samp{-ansi} is
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used because they do not have an ISO standard meaning.
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GCC normally generates special code to handle certain builtin functions
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more efficiently; for instance, calls to @code{alloca} may become single
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@ -826,10 +802,6 @@ and faster, but since the function calls no longer appear as such, you
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cannot set a breakpoint on those calls, nor can you change the behavior
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of the functions by linking with a different library.
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The @samp{-ansi} option prevents @code{alloca}, @code{ffs} and @code{_exit}
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from being builtin functions, since these functions do not have an ANSI
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standard meaning.
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@item -fhosted
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@cindex hosted environment
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