Definition notint (v: aval) :=
  match v with
  | I i => I (Int.not i)
  | Uns p n => sgn p (n + 1)
  | Sgn p n => Sgn p n
  | _ => ntop1 v
  end.

Lemma notint_sound: forall v x, vmatch v x -> vmatch (Val.notint v) (notint x).