diff options
Diffstat (limited to 'contrib/gcc/doc/extend.texi')
| -rw-r--r-- | contrib/gcc/doc/extend.texi | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/contrib/gcc/doc/extend.texi b/contrib/gcc/doc/extend.texi index d27af10..c6bd57d 100644 --- a/contrib/gcc/doc/extend.texi +++ b/contrib/gcc/doc/extend.texi @@ -1577,6 +1577,7 @@ The keyword @code{__attribute__} allows you to specify special attributes when making a declaration. This keyword is followed by an attribute specification inside double parentheses. The following attributes are currently defined for functions on all targets: +@code{aligned}, @code{noreturn}, @code{returns_twice}, @code{noinline}, @code{always_inline}, @code{flatten}, @code{pure}, @code{const}, @code{nothrow}, @code{sentinel}, @code{format}, @code{format_arg}, @code{no_instrument_function}, @@ -1615,6 +1616,27 @@ is not defined in the same translation unit. Not all target machines support this attribute. +@item aligned (@var{alignment}) +@cindex @code{aligned} attribute +This attribute specifies a minimum alignment for the function, +measured in bytes. + +You cannot use this attribute to decrease the alignment of a function, +only to increase it. However, when you explicitly specify a function +alignment this will override the effect of the +@option{-falign-functions} (@pxref{Optimize Options}) option for this +function. + +Note that the effectiveness of @code{aligned} attributes may be +limited by inherent limitations in your linker. On many systems, the +linker is only able to arrange for functions to be aligned up to a +certain maximum alignment. (For some linkers, the maximum supported +alignment may be very very small.) See your linker documentation for +further information. + +The @code{aligned} attribute can also be used for variables and fields +(@pxref{Variable Attributes}.) + @item always_inline @cindex @code{always_inline} function attribute Generally, functions are not inlined unless optimization is specified. @@ -3044,6 +3066,9 @@ up to a maximum of 8 byte alignment, then specifying @code{aligned(16)} in an @code{__attribute__} will still only provide you with 8 byte alignment. See your linker documentation for further information. +The @code{aligned} attribute can also be used for functions +(@pxref{Function Attributes}.) + @item cleanup (@var{cleanup_function}) @cindex @code{cleanup} attribute The @code{cleanup} attribute runs a function when the variable goes @@ -6146,6 +6171,16 @@ Similar to @code{__builtin_powi}, except the argument and return types are @code{long double}. @end deftypefn +@deftypefn {Built-in Function} int32_t __builtin_bswap32 (int32_t x) +Returns @var{x} with the order of the bytes reversed; for example, +@code{0xaabbccdd} becomes @code{0xddccbbaa}. Byte here always means +exactly 8 bits. +@end deftypefn + +@deftypefn {Built-in Function} int64_t __builtin_bswap64 (int64_t x) +Similar to @code{__builtin_bswap32}, except the argument and return types +are 64-bit. +@end deftypefn @node Target Builtins @section Built-in Functions Specific to Particular Target Machines |
