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 val_hiword_longofwords:
forall v1 v2, Val.lessdef (Val.hiword (Val.longofwords v1 v2)) v1.