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 undef_regs_outside:
forall ml ls l,
Loc.notin l (map R ml) -> undef_regs ml ls l = ls l.