netbsd man page for __builtin_return_address

__BUILTIN_RETURN_ADDRESS(3)				   BSD Library Functions Manual 			       __BUILTIN_RETURN_ADDRESS(3)

NAME
     __builtin_return_address -- the return address of a function

SYNOPSIS
     void *
     __builtin_return_address(unsigned int level);

     void *
     __builtin_frame_address(unsigned int level);

DESCRIPTION
     The __builtin_return_address() is a GNU extension for obtaining the return address of the current function or one of the callers of the cur-
     rent function.

     The parameter level specifies the number of frames that should be scanned up in the call stack.  A value 0 returns the address of the current
     function, a value 1 requests the address of the caller of the current function, a value 2 asks for the address of the caller's caller, and so
     forth.  If the top of the call stack has been reached, the function will return 0.  Note also that on some architectures it is only possible
     to determine the address of the current function.	In such cases a value 0 is returned.  Thus, it is usually safe to only use the value 0 for
     level.

     The __builtin_frame_address() behaves similarly, but returns the address of the function frame rather than the return address of the func-
     tion.

SEE ALSO
     gcc(1), __builtin_object_size(3)

CAVEATS
     These are non-standard, compiler-specific extensions.

BSD
								 December 19, 2010							       BSD