http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59539
--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Because otherwise it can generate an aligned load, and I thought when user explicitly writes he wants an unaligned load we should honor it, perhaps for some reason the alignment info can't be trusted etc. ix86_expand_vector_move_misalign also checks misaligned_operand and only emits the non-UNSPEC insn for TARGET_AVX if it will result in misaligned load.