(* Lemma extcall_arg_erasure: *)
(*   forall m m' loc arg rs rs' ev *)
(*     (Harg: extcall_arg rs m loc arg) *)
(*     (Harg_ev: Asm_event.extcall_arg_ev rs m loc arg ev) *)
(*     (Hmem_obs_eq: mem_erasure m m') *)
(*     (Hrs : regs_erasure rs rs'), *)
(*   exists arg' ev', *)
(*     Asm_event.extcall_arg_ev rs' m' loc arg' ev' /\ *)
(*     extcall_arg rs' m' loc arg' /\ *)
(*     val_erasure arg arg' /\ *)
(*     mem_event_list_erasure ev ev'. *)
(* Proof with eauto with val_erasure regs_erasure. *)
(*   intros. *)
(*   inversion Harg; subst. *)
(*   - inversion Harg_ev; subst. *)
(*     exists (rs' (preg_of r)), [::]; *)
(*     (repeat split); try econstructor... *)
(*   - inversion Harg_ev; subst. *)
(*     eapply mem_loadv_erased in H0; eauto. *)
(*     destruct H0 as [arg' [Hload' Harg_erasure]]. *)
(*     eapply loadbytes_erasure in H6; eauto. *)
(*     destruct H6 as [bytes' [Hloadbytes' Hbytes_erasure]]. *)
(*     rewrite H3 in Hload'. simpl in Hload'. *)
(*     assert (Val.add (rs' ESP) (Vint (Int.repr (Stacklayout.fe_ofs_arg + 4 * ofs))) *)
(*             = Vptr b z) *)
(*       by (eapply val_erasure_add_result; eauto with val_erasure regs_erasure ). *)
(*       exists arg', [:: Read b (Int.unsigned z) (size_chunk (chunk_of_type ty)) *)
(*                 bytes']. *)
(*     (repeat split); try econstructor... *)
(*     eapply Mem.loadbytes_load in Hloadbytes'; eauto. *)
(*     rewrite Hloadbytes' in Hload'. inv Hload'. *)
(*     reflexivity. *)
(*     rewrite H. simpl; auto. *)
(*     econstructor; eauto. *)
(*     constructor. *)
(* Qed. *)
(* Lemma extcall_arg_pair_erasure: *)
(*   forall m m' loc arg rs rs' ev *)
(*     (Harg_ev: Asm_event.extcall_arg_pair_ev rs m loc arg ev) *)
(*     (Hmem_obs_eq: mem_erasure m m') *)
(*     (Hrs : regs_erasure rs rs'), *)
(*   exists arg' ev', *)
(*     Asm_event.extcall_arg_pair_ev rs' m' loc arg' ev' /\ *)
(*     extcall_arg_pair rs' m' loc arg' /\ *)
(*     val_erasure arg arg' /\ *)
(*     mem_event_list_erasure ev ev'. *)
(* Proof with eauto with val_erasure regs_erasure. *)
(*   intros. *)
(*   inv Harg_ev. *)
(*   - pose proof (Asm_event.extcall_arg_ev_extcall_arg _ _ _ _ _ H). *)
(*     eapply extcall_arg_erasure in H; eauto. *)
(*     destruct H as [? [? [? [? [? ?]]]]]. *)
(*     do 2 eexists; (repeat split); try econstructor... *)
(*   - pose proof (Asm_event.extcall_arg_ev_extcall_arg _ _ _ _ _ H). *)
(*     pose proof (Asm_event.extcall_arg_ev_extcall_arg _ _ _ _ _ H0). *)
(*     eapply extcall_arg_erasure in H; eauto. *)
(*     eapply extcall_arg_erasure in H0; eauto. *)
(*     destruct H as [vhi' [T1' [? [? [? ?]]]]]. *)
(*     destruct H0 as [vlo' [T2' [? [? [? ?]]]]]. *)
(*     exists (Val.longofwords vhi' vlo'), (T1' ++ T2'). *)
(*     (repeat split); try econstructor... *)
(*     eapply mem_event_list_erasure_cat; eauto. *)
(* Qed. *)
(* Lemma extcall_arguments_erasure: *)
(*   forall m m' ef args rs rs' ev *)
(*     (Hexternal_ev: Asm_event.extcall_arguments_ev rs m (ef_sig ef) args ev) *)
(*     (Hmem_obs_eq: mem_erasure m m') *)
(*     (Hrs : regs_erasure rs rs'), *)
(*   exists args' ev', *)
(*     Asm_event.extcall_arguments_ev rs' m' (ef_sig ef) args' ev' /\ *)
(*     extcall_arguments rs' m' (ef_sig ef) args' /\ *)
(*     val_erasure_list args args' /\ *)
(*     mem_event_list_erasure ev ev'. *)
(* Proof. *)
(*   intros. *)
(*   unfold extcall_arguments, Asm_event.extcall_arguments_ev in *. *)
(*   generalize dependent ev. *)
(*   generalize dependent (Conventions1.loc_arguments (ef_sig ef)). *)
(*   induction args; intros. *)
(*   - inv Hexternal_ev. *)
(*     exists [::], [::]. *)
(*     repeat split; *)
(*       constructor. *)
(*   - inv Hexternal_ev. *)
(*     destruct (IHargs _ _ H6) as (args' & T2' & Hargs_ev & *)
(*                                     Hls & Hargs_erasure & HT_erasure2). *)
(*     eapply extcall_arg_pair_erasure in H4; eauto. *)
(*     destruct H4 as (arg' & T1' & Harg_ev' & Harg' & Harg_erasure' & HT_erasure1). *)
(*     exists (arg' :: args'), (T1' ++ T2'). *)
(*     repeat split; try econstructor; eauto. *)
(*     eapply mem_event_list_erasure_cat; eauto. *)
(* Qed. *)

Lemma builtin_event_erasure:
forall ef m1 m1' vs1 vs1' T1
(Hmem: mem_erasure m1 m1')
(Hval_erasure: val_erasure_list vs1 vs1')
(Hbuiltin: Asm_event.builtin_event ef m1 vs1 T1),
exists T1',
Asm_event.builtin_event ef m1' vs1' T1' /\
mem_event_list_erasure T1 T1'.