http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60086
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> --- As of posix_memalign the issue is not so much that of alias analysis (we could handle it but we don't have a builtin right now) but that of alignment analysis which doesn't implement alignment tracking of pointers stored in memory. We could "lower" posix_memalign (&ptr, align, size); to posix_memalign (&ptr, align, size); ptr = __builtin_assume_algined (ptr, align); and hope for FRE to fix things up enough to make that useful. I have opened PR60092.