Definition rol (x: nval) (amount: int) :=
match x with
| Nothing => Nothing
| I m => I (Int.ror m amount)
| All => All
end.

(* Specifications: *)
Lemma rol_sound:
forall v w x n,
vagree v w (rol x n) ->
vagree (Val.rol v (Vint n)) (Val.rol w (Vint n)) x.