http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56443
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2013-02-25 13:11:08 UTC --- Created attachment 29535 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29535 gcc48-pr56443.patch Untested fix. Going forward, you want to avoid using the overaligned types for these purposes, better use __builtin_assume_aligned.
