2009-08-06 Thomas Schwinge <tschwinge@gnu.org>

	* gcc/doc/extend.texi (__builtin_extract_return_address)
	(__builtin_frob_return_address): Document.

From-SVN: r150546

gcc/ChangeLog

+2009-08-06  Thomas Schwinge  <tschwinge@gnu.org>
+
+	* gcc/doc/extend.texi (__builtin_extract_return_address)
+	(__builtin_frob_return_address): Document.
+
 2009-08-06  Paul Brook  <paul@codesourcery.com>
 
 	* config/arm/lib1funcs.asm (ARM_DIV_BODY): Add Thumb-2 implementation.

gcc/doc/extend.texi

@@ -5844,10 +5844,27 @@ of the stack has been reached, this function will return @code{0} or a
 random value.  In addition, @code{__builtin_frame_address} may be used
 to determine if the top of the stack has been reached.
 
+Additional post-processing of the returned value may be needed, see
+@code{__builtin_extract_return_address}.
+
 This function should only be used with a nonzero argument for debugging
 purposes.
 @end deftypefn
 
+@deftypefn {Built-in Function} {void *} __builtin_extract_return_address (void *@var{addr})
+The address as returned by @code{__builtin_return_address} may have to be fed
+through this function to get the actual encoded address.  For example, on the
+31-bit S/390 platform the highest bit has to be masked out, or on SPARC
+platforms an offset has to be added for the true next instruction to be
+executed.
+
+If no fixup is needed, this function simply passes through @var{addr}.
+@end deftypefn
+
+@deftypefn {Built-in Function} {void *} __builtin_frob_return_address (void *@var{addr})
+This function does the reverse of @code{__builtin_extract_return_address}.
+@end deftypefn
+
 @deftypefn {Built-in Function} {void *} __builtin_frame_address (unsigned int @var{level})
 This function is similar to @code{__builtin_return_address}, but it
 returns the address of the function frame rather than the return address