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Diffstat (limited to 'gcc/doc/extend.texi')
| -rw-r--r-- | gcc/doc/extend.texi | 20 |
1 files changed, 14 insertions, 6 deletions
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi index dba8b4382b2..23e6a76b8a8 100644 --- a/gcc/doc/extend.texi +++ b/gcc/doc/extend.texi @@ -10316,14 +10316,22 @@ recommend general use of these functions. The remaining functions are provided for optimization purposes. +With the exception of built-ins that have library equivalents such as +the standard C library functions discussed below, or that expand to +library calls, GCC built-in functions are always expanded inline and +thus do not have corresponding entry points and their address cannot +be obtained. Attempting to use them in an expression other than +a function call results in a compile-time error. + @opindex fno-builtin GCC includes built-in versions of many of the functions in the standard -C library. The versions prefixed with @code{__builtin_} are always -treated as having the same meaning as the C library function even if you -specify the @option{-fno-builtin} option. (@pxref{C Dialect Options}) -Many of these functions are only optimized in certain cases; if they are -not optimized in a particular case, a call to the library function is -emitted. +C library. These functions come in two forms: one whose names start with +the @code{__builtin_} prefix, and the other without. Both forms have the +same type (including prototype), the same address (when their address is +taken), and the same meaning as the C library functions even if you specify +the @option{-fno-builtin} option @pxref{C Dialect Options}). Many of these +functions are only optimized in certain cases; if they are not optimized in +a particular case, a call to the library function is emitted. @opindex ansi @opindex std |