Remark val_lessdef_normalize:
  forall v v' ty,
  Val.has_type v ty -> Val.lessdef v v' ->
  Val.lessdef v (Val.load_result (chunk_of_type ty) v').

Lemma can_undef_satisf: forall ml e rs ls, can_undef ml e = true -> satisf rs ls e -> satisf rs (undef_regs ml ls) e.