Ltac inv_safe H :=
  inv H;
  try solve[match goal with
    | H : semantics.at_external _ _ _ = _ |- _ =>
      simpl in H; congruence
    | H : j_at_external _ _ _ = _ |- _ =>
      simpl in H; congruence
    | H : semantics.halted _ _ _ |- _ =>
      simpl in H; unfold cl_halted in H; contradiction
  end].

(* Specifications: *)
Lemma semax_seq: forall Delta (R: ret_assert) P Q h t, semax Espec Delta P h (overridePost Q R) -> semax Espec Delta Q t R -> semax Espec Delta P (Clight.Ssequence h t) R.
Lemma control_as_safe_refl psi n k : control_as_safe psi n k k.
Lemma semax_loop: forall Delta Q Q' incr body R, semax Espec Delta Q body (loop1_ret_assert Q' R) -> semax Espec Delta Q' incr (loop2_ret_assert Q R) -> semax Espec Delta Q (Sloop body incr) R.
Lemma semax_break: forall Delta Q, semax Espec Delta (RA_break Q) Sbreak Q.
Lemma semax_continue: forall Delta Q, semax Espec Delta (RA_continue Q) Scontinue Q.