http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58280
--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> --- We have a way to say assume something, if (ldim % 32 != 0) __builtin_unreachable (), and you can define a __assume macro using it. But, as we don't record the non-zero bitmasks from it anywhere, it can't be used by later optimization passes yet.
