http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57017
--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-04-24 06:15:46 UTC --- Can't reproduce, perhaps misconfigured compiler? HAVE_AS_IX86_REP_LOCK_PREFIX test in particular. You haven't said what target it is and how you've configured the compiler...