diff options
Diffstat (limited to 'gcc/doc/extend.texi')
| -rw-r--r-- | gcc/doc/extend.texi | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index 8a1d8fe..0fedab9 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -13003,6 +13003,7 @@ is called and the @var{flag} argument passed to it. @findex __builtin_isless @findex __builtin_islessequal @findex __builtin_islessgreater +@findex __builtin_issignaling @findex __builtin_isunordered @findex __builtin_object_size @findex __builtin_powi @@ -13558,6 +13559,8 @@ In the same fashion, GCC provides @code{fpclassify}, @code{isfinite}, @code{isinf_sign}, @code{isnormal} and @code{signbit} built-ins used with @code{__builtin_} prefixed. The @code{isinf} and @code{isnan} built-in functions appear both with and without the @code{__builtin_} prefix. +With @code{-ffinite-math-only} option the @code{isinf} and @code{isnan} +built-in functions will always return 0. GCC provides built-in versions of the ISO C99 floating-point rounding and exceptions handling functions @code{fegetround}, @code{feclearexcept} and @@ -14491,6 +14494,20 @@ Similar to @code{__builtin_nans}, except the return type is @code{_Float@var{n}x}. @end deftypefn +@deftypefn {Built-in Function} int __builtin_issignaling (...) +Return non-zero if the argument is a signaling NaN and zero otherwise. +Note while the parameter list is an +ellipsis, this function only accepts exactly one floating-point +argument. GCC treats this parameter as type-generic, which means it +does not do default promotion from float to double. +This built-in function can work even without the non-default +@code{-fsignaling-nans} option, although if a signaling NaN is computed, +stored or passed as argument to some function other than this built-in +in the current translation unit, it is safer to use @code{-fsignaling-nans}. +With @code{-ffinite-math-only} option this built-in function will always +return 0. +@end deftypefn + @deftypefn {Built-in Function} int __builtin_ffs (int x) Returns one plus the index of the least significant 1-bit of @var{x}, or if @var{x} is zero, returns zero. |