https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87843
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> --- If we have less MEM_REFs then we probably strip them because we think they reference equal types. I think I already told you that given that MEM_REFs use pointer types to carry alignment info _those_ may not become incomplete! But I didn't expect that to cause wrong-code but missed optimizations.
