http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54533
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-09-09 07:01:52 UTC --- I have seen a bug about this before but I cannot find it. It only happen on x86_64 as al tells the function if it uses floating point arguments or not. It might be a bug in gdb in figuring out the prologue of the function too.
