End DEFAULT.
(** ** Detecting operations that are redundant and can be turned into a move *)
Definition andimm_redundant (x: nval) (n: int) :=
match x with
| Nothing => true
| I m => Int.eq_dec (Int.and m (Int.not n)) Int.zero
| _ => false
end.

Lemma andimm_redundant_sound:
forall v w x n,
andimm_redundant x n = true ->
vagree v w (andimm x n) ->
vagree (Val.and v (Vint n)) w x.