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_incr: forall bc bc' e ae, ematch bc e ae -> bc_incr bc bc' -> ematch bc' e ae.