Fixpoint eforget (rl: list reg) (ae: aenv) {struct rl} : aenv :=
  match rl with
  | nil => ae
  | r1 :: rs => eforget rs (AE.set r1 Vtop ae)
  end.

Lemma ematch_forget: forall e rl ae, ematch e ae -> ematch e (eforget rl ae).