diff options
Diffstat (limited to 'gcc/doc/extend.texi')
| -rw-r--r-- | gcc/doc/extend.texi | 39 |
1 files changed, 32 insertions, 7 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index bf08a41f715..ed4b30cfc05 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -1701,13 +1701,14 @@ 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{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}, -@code{section}, @code{constructor}, @code{destructor}, @code{used}, -@code{unused}, @code{deprecated}, @code{weak}, @code{malloc}, -@code{alias}, @code{warn_unused_result}, @code{nonnull}, -@code{gnu_inline} and @code{externally_visible}, @code{hot}, @code{cold}. +@code{alloc_size}, @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}, @code{section}, @code{constructor}, +@code{destructor}, @code{used}, @code{unused}, @code{deprecated}, +@code{weak}, @code{malloc}, @code{alias}, @code{warn_unused_result}, +@code{nonnull}, @code{gnu_inline} and @code{externally_visible}, +@code{hot}, @code{cold}. Several other attributes are defined for functions on particular target systems. Other attributes, including @code{section} are supported for variables declarations (@pxref{Variable Attributes}) and for types (@pxref{Type @@ -1740,6 +1741,30 @@ is not defined in the same translation unit. Not all target machines support this attribute. +@item alloc_size +@cindex @code{alloc_size} attribute +The @code{alloc_size} attribute is used to tell the compiler that the +function return value points to memory, where the size is given by +one or two of the functions parameters. GCC uses this +information to improve the correctness of @code{__builtin_object_size}. + +The function parameter(s) denoting the allocated size are specified by +one or two integer arguments supplied to the attribute. The allocated size +is either the value of the single function argument specified or the product +of the two function arguments specified. Argument numbering starts at +one. + +For instance, + +@smallexample +void* my_calloc(size_t, size_t) __attribute__((alloc_size(1,2))) +void my_realloc(void* size_t) __attribute__((alloc_size(2))) +@end smallexample + +declares that my_calloc will return memory of the size given by +the product of parameter 1 and 2 and that my_realloc will return memory +of the size given by parameter 2. + @item always_inline @cindex @code{always_inline} function attribute Generally, functions are not inlined unless optimization is specified. |