[Bug target/54087] __atomic_fetch_add does not use xadd instruction

[drepper.fsp at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54087

--- Comment #8 from Ulrich Drepper <drepper.fsp at gmail dot com> 2012-08-23 15:41:49 UTC ---
(In reply to comment #7)
> Check to see if it solves the problem as well.

I tested it.  Seems to  work in all cases and does not disturb other
optimizations like comparisons with zero.