(** ** Lemmas about erased values*)

  Definition isDefined v :=
    match v with
    | Vundef => false
    | _ => true
    end.

Lemma val_erasure_cmp_bool: forall c v1 v1', v1 <> Vundef -> val_erasure v1 v1' -> Val.cmp_bool c v1 Vzero = Val.cmp_bool c v1' Vzero.