Definition val_inject_opt (j: meminj) (v1 v2: option val) :=
  match v1, v2 with Some v1', Some v2' => val_inject j v1' v2'
  | None, None => True
  | _, _ => False
  end.

Lemma forall_lessdef_val_listless: forall args args' (H: Forall2 Val.lessdef args args'), Val.lessdef_list args args' .