diff options
Diffstat (limited to 'gcc/doc')
| -rw-r--r-- | gcc/doc/extend.texi | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index 730940a49dd..633913bb88d 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -583,6 +583,41 @@ myprintf (FILE *f, const char *format, ...) @end smallexample @end deftypefn +@deftypefn {Built-in Function} __builtin_va_arg_pack_len () +This built-in function returns the number of anonymous arguments of +an inline function. It can be used only in inline functions which +will be always inlined, never compiled as a separate function, such +as those using @code{__attribute__ ((__always_inline__))} or +@code{__attribute__ ((__gnu_inline__))} extern inline functions. +For example following will do link or runtime checking of open +arguments for optimized code: +@smallexample +#ifdef __OPTIMIZE__ +extern inline __attribute__((__gnu_inline__)) int +myopen (const char *path, int oflag, ...) +@{ + if (__builtin_va_arg_pack_len () > 1) + warn_open_too_many_arguments (); + + if (__builtin_constant_p (oflag)) + @{ + if ((oflag & O_CREAT) != 0 && __builtin_va_arg_pack_len () < 1) + @{ + warn_open_missing_mode (); + return __open_2 (path, oflag); + @} + return open (path, oflag, __builtin_va_arg_pack ()); + @} + + if (__builtin_va_arg_pack_len () < 1) + return __open_2 (path, oflag); + + return open (path, oflag, __builtin_va_arg_pack ()); +@} +#endif +@end smallexample +@end deftypefn + @node Typeof @section Referring to a Type with @code{typeof} @findex typeof |
