Remark decompose_int_thumb_nil:
  forall N n p, decompose_int_thumb N n p = nil -> n = Int.zero.

Lemma decompose_int_bic: forall n v, List.fold_left (fun v i => Val.and v (Vint (Int.not i))) (decompose_int n) v = Val.and v (Vint (Int.not n)).