https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61320
--- Comment #51 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- > Ah, we also expand one from a TARGET_MEM_REF: > > ;; basic block 76, loop depth 2 > ;; pred: 79 > load_dst_215 = MEM[base: ptr_110, offset: 0B]; > > and TARGET_MEM_REF only handles the movmisalign case. So it's either IVOPTs > not punting properly here (it does for unaligned accesses - grep for > STRICT_ALIGNMENT) or we need to put a bitfield extraction case into > TARGET_MEM_REF expansion (IMHO that's missing anyway, IVOPTs is too much > pessimized by not considering this). TARGET_MEM_REF is supposed to be a valid memory access for the target though and, by definition, an unaligned access is not valid for a strict alignment target (unless you have a movmisalign pattern), so the problem is the TARGET_MEM_REF. If you want to make IVOPTS generate unaligned TARGET_MEM_REFs, you'll need to make sure that the costs are properly adjusted and benchmark the result.
