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+(* *************************************************************)
+(* *)
+(* The Compcert verified compiler *)
+(* *)
+(* Sylvain Boulmé Grenoble-INP, VERIMAG *)
+(* *)
+(* Copyright VERIMAG. All rights reserved. *)
+(* This file is distributed under the terms of the INRIA *)
+(* Non-Commercial License Agreement. *)
+(* *)
+(* *************************************************************)
+
+(** Implementation of a simulation test (ie a "scheduling verifier") for the sequential semantics of Abstract Basic Blocks.
+
+It is based on a symbolic execution procedure of Abstract Basic Blocks with imperative hash-consing and rewriting.
+
+It also provides debugging information when the test fails.
+
+
+*)
+
+Require Export Impure.ImpHCons. (**r Import the Impure library. See https://github.com/boulme/ImpureDemo *)
+Export Notations.
+Import HConsing.
+
+Require Import Coq.Bool.Bool.
+Require Export SeqSimuTheory.
+Require Import PArith.
+
+
+Local Open Scope impure.
+
+Import ListNotations.
+Local Open Scope list_scope.
+
+
+Definition FULL_DEBUG_DUMP : bool := false. (* print debug traces, even if the verifier succeeds. *)
+
+(** * Interface of (impure) equality tests for operators *)
+Module Type ImpParam.
+
+Include LangParam.
+
+Parameter op_eq: op -> op -> ?? bool.
+
+Parameter op_eq_correct: forall o1 o2,
+ WHEN op_eq o1 o2 ~> b THEN
+ b=true -> o1 = o2.
+
+End ImpParam.
+
+
+Module Type ISeqLanguage.
+
+Declare Module LP: ImpParam.
+
+Include MkSeqLanguage LP.
+
+End ISeqLanguage.
+
+
+(** * A generic dictinary on PseudoRegisters with an impure equality test *)
+
+Module Type ImpDict.
+
+Declare Module R: PseudoRegisters.
+
+Parameter t: Type -> Type.
+
+Parameter get: forall {A}, t A -> R.t -> option A.
+
+Parameter set: forall {A}, t A -> R.t -> A -> t A.
+
+Parameter set_spec_eq: forall A d x (v: A),
+ get (set d x v) x = Some v.
+
+Parameter set_spec_diff: forall A d x y (v: A),
+ x <> y -> get (set d x v) y = get d y.
+
+Parameter rem: forall {A}, t A -> R.t -> t A.
+
+Parameter rem_spec_eq: forall A (d: t A) x,
+ get (rem d x) x = None.
+
+Parameter rem_spec_diff: forall A (d: t A) x y,
+ x <> y -> get (rem d x) y = get d y.
+
+Parameter empty: forall {A}, t A.
+
+Parameter empty_spec: forall A x,
+ get (empty (A:=A)) x = None.
+
+Parameter eq_test: forall {A}, t A -> t A -> ?? bool.
+
+Parameter eq_test_correct: forall A (d1 d2: t A),
+ WHEN eq_test d1 d2 ~> b THEN
+ b=true -> forall x, get d1 x = get d2 x.
+
+(* NB: we could also take an eq_test on R.t (but not really useful with "pure" dictionaries *)
+
+(** only for debugging *)
+Parameter not_eq_witness: forall {A}, t A -> t A -> ?? option R.t.
+
+End ImpDict.
+
+
+(** * Specification of the provided tests *)
+Module Type ImpSimuInterface.
+
+Declare Module CoreL: ISeqLanguage.
+Import CoreL.
+Import Terms.
+
+(** the silent test (without debugging informations) *)
+Parameter bblock_simu_test: reduction -> bblock -> bblock -> ?? bool.
+
+Parameter bblock_simu_test_correct: forall reduce (p1 p2 : bblock),
+ WHEN bblock_simu_test reduce p1 p2 ~> b
+ THEN b = true -> forall ge : genv, bblock_simu ge p1 p2.
+
+(** the verbose test extended with debugging informations *)
+Parameter verb_bblock_simu_test
+ : reduction ->
+ (R.t -> ?? pstring) ->
+ (op -> ?? pstring) -> bblock -> bblock -> ?? bool.
+
+Parameter verb_bblock_simu_test_correct:
+ forall reduce
+ (string_of_name : R.t -> ?? pstring)
+ (string_of_op : op -> ?? pstring)
+ (p1 p2 : bblock),
+ WHEN verb_bblock_simu_test reduce string_of_name string_of_op p1 p2 ~> b
+ THEN b = true -> forall ge : genv, bblock_simu ge p1 p2.
+
+End ImpSimuInterface.
+
+
+(** * Implementation of the provided tests *)
+
+Module ImpSimu (L: ISeqLanguage) (Dict: ImpDict with Module R:=L.LP.R): ImpSimuInterface with Module CoreL := L.
+
+Module CoreL:=L.
+
+Module ST := SimuTheory L.
+
+Import ST.
+Import Terms.
+
+Definition term_set_hid (t: term) (hid: hashcode): term :=
+ match t with
+ | Input x _ => Input x hid
+ | App op l _ => App op l hid
+ end.
+
+Definition list_term_set_hid (l: list_term) (hid: hashcode): list_term :=
+ match l with
+ | LTnil _ => LTnil hid
+ | LTcons t l' _ => LTcons t l' hid
+ end.
+
+Lemma term_eval_set_hid ge t hid m:
+ term_eval ge (term_set_hid t hid) m = term_eval ge t m.
+Proof.
+ destruct t; cbn; auto.
+Qed.
+
+Lemma list_term_eval_set_hid ge l hid m:
+ list_term_eval ge (list_term_set_hid l hid) m = list_term_eval ge l m.
+Proof.
+ destruct l; cbn; auto.
+Qed.
+
+(* Local nickname *)
+Module D:=ImpPrelude.Dict.
+
+Section SimuWithReduce.
+
+Variable reduce: reduction.
+
+Section CanonBuilding. (** Implementation of the symbolic execution (ie a "canonical form" representing the semantics of an abstract basic block) *)
+
+Variable hC_term: hashinfo term -> ?? term.
+Hypothesis hC_term_correct: forall t, WHEN hC_term t ~> t' THEN forall ge m, term_eval ge (hdata t) m = term_eval ge t' m.
+
+Variable hC_list_term: hashinfo list_term -> ?? list_term.
+Hypothesis hC_list_term_correct: forall t, WHEN hC_list_term t ~> t' THEN forall ge m, list_term_eval ge (hdata t) m = list_term_eval ge t' m.
+
+(* First, we wrap constructors for hashed values !*)
+
+Local Open Scope positive.
+Local Open Scope list_scope.
+
+Definition hInput_hcodes (x:R.t) :=
+ DO hc <~ hash 1;;
+ DO hv <~ hash x;;
+ RET [hc;hv].
+Extraction Inline hInput_hcodes.
+
+Definition hInput (x:R.t): ?? term :=
+ DO hv <~ hInput_hcodes x;;
+ hC_term {| hdata:=Input x unknown_hid; hcodes :=hv; |}.
+
+Lemma hInput_correct x:
+ WHEN hInput x ~> t THEN forall ge m, term_eval ge t m = Some (m x).
+Proof.
+ wlp_simplify.
+Qed.
+Global Opaque hInput.
+Hint Resolve hInput_correct: wlp.
+
+Definition hApp_hcodes (o:op) (l: list_term) :=
+ DO hc <~ hash 2;;
+ DO hv <~ hash o;;
+ RET [hc;hv;list_term_get_hid l].
+Extraction Inline hApp_hcodes.
+
+Definition hApp (o:op) (l: list_term) : ?? term :=
+ DO hv <~ hApp_hcodes o l;;
+ hC_term {| hdata:=App o l unknown_hid; hcodes:=hv |}.
+
+Lemma hApp_correct o l:
+ WHEN hApp o l ~> t THEN forall ge m,
+ term_eval ge t m = match list_term_eval ge l m with
+ | Some v => op_eval ge o v
+ | None => None
+ end.
+Proof.
+ wlp_simplify.
+Qed.
+Global Opaque hApp.
+Hint Resolve hApp_correct: wlp.
+
+Definition hLTnil (_: unit): ?? list_term :=
+ hC_list_term {| hdata:=LTnil unknown_hid; hcodes := nil; |} .
+
+Lemma hLTnil_correct x:
+ WHEN hLTnil x ~> l THEN forall ge m, list_term_eval ge l m = Some nil.
+Proof.
+ wlp_simplify.
+Qed.
+Global Opaque hLTnil.
+Hint Resolve hLTnil_correct: wlp.
+
+
+Definition hLTcons (t: term) (l: list_term): ?? list_term :=
+ hC_list_term {| hdata:=LTcons t l unknown_hid; hcodes := [term_get_hid t; list_term_get_hid l]; |}.
+
+Lemma hLTcons_correct t l:
+ WHEN hLTcons t l ~> l' THEN forall ge m,
+ list_term_eval ge l' m = match term_eval ge t m, list_term_eval ge l m with
+ | Some v, Some lv => Some (v::lv)
+ | _, _ => None
+ end.
+Proof.
+ wlp_simplify.
+Qed.
+Global Opaque hLTcons.
+Hint Resolve hLTcons_correct: wlp.
+
+(* Second, we use these hashed constructors ! *)
+
+Record hsmem:= {hpre: list term; hpost:> Dict.t term}.
+
+(** evaluation of the post-condition *)
+Definition hsmem_post_eval ge (hd: Dict.t term) x (m:mem) :=
+ match Dict.get hd x with
+ | None => Some (m x)
+ | Some ht => term_eval ge ht m
+ end.
+
+Definition hsmem_get (d:hsmem) x: ?? term :=
+ match Dict.get d x with
+ | None => hInput x
+ | Some t => RET t
+ end.
+
+Lemma hsmem_get_correct (d:hsmem) x:
+ WHEN hsmem_get d x ~> t THEN forall ge m, term_eval ge t m = hsmem_post_eval ge d x m.
+Proof.
+ unfold hsmem_get, hsmem_post_eval; destruct (Dict.get d x); wlp_simplify.
+Qed.
+Global Opaque hsmem_get.
+Hint Resolve hsmem_get_correct: wlp.
+
+Local Opaque allvalid.
+
+Definition smem_model ge (d: smem) (hd:hsmem): Prop :=
+ (forall m, allvalid ge hd.(hpre) m <-> smem_valid ge d m)
+ /\ (forall m x, smem_valid ge d m -> hsmem_post_eval ge hd x m = (ST.term_eval ge (d x) m)).
+
+Lemma smem_model_smem_valid_alt ge d hd: smem_model ge d hd ->
+ forall m x, smem_valid ge d m -> hsmem_post_eval ge hd x m <> None.
+Proof.
+ intros (H1 & H2) m x H. rewrite H2; auto.
+ unfold smem_valid in H. intuition eauto.
+Qed.
+
+Lemma smem_model_allvalid_alt ge d hd: smem_model ge d hd ->
+ forall m x, allvalid ge hd.(hpre) m -> hsmem_post_eval ge hd x m <> None.
+Proof.
+ intros (H1 & H2) m x H. eapply smem_model_smem_valid_alt.
+ - split; eauto.
+ - rewrite <- H1; auto.
+Qed.
+
+Definition naive_set (hd:hsmem) x (t:term) :=
+ {| hpre:= t::hd.(hpre); hpost:=Dict.set hd x t |}.
+
+Lemma naive_set_correct hd x ht ge d t:
+ smem_model ge d hd ->
+ (forall m, smem_valid ge d m -> term_eval ge ht m = ST.term_eval ge t m) ->
+ smem_model ge (smem_set d x t) (naive_set hd x ht).
+Proof.
+ unfold naive_set; intros (DM0 & DM1) EQT; split.
+ - intros m.
+ destruct (DM0 m) as (PRE & VALID0); clear DM0.
+ assert (VALID1: allvalid ge hd.(hpre) m -> pre d ge m). { unfold smem_valid in PRE; tauto. }
+ assert (VALID2: allvalid ge hd.(hpre) m -> forall x : Dict.R.t, ST.term_eval ge (d x) m <> None). { unfold smem_valid in PRE; tauto. }
+ rewrite !allvalid_extensionality in * |- *; cbn.
+ intuition (subst; eauto).
+ + eapply smem_valid_set_proof; eauto.
+ erewrite <- EQT; eauto.
+ + exploit smem_valid_set_decompose_1; eauto.
+ intros X1; exploit smem_valid_set_decompose_2; eauto.
+ rewrite <- EQT; eauto.
+ + exploit smem_valid_set_decompose_1; eauto.
+ - clear DM0. unfold hsmem_post_eval, hsmem_post_eval in * |- *; cbn.
+ Local Hint Resolve smem_valid_set_decompose_1: core.
+ intros; case (R.eq_dec x x0).
+ + intros; subst; rewrite !Dict.set_spec_eq; cbn; eauto.
+ + intros; rewrite !Dict.set_spec_diff; cbn; eauto.
+Qed.
+Local Hint Resolve naive_set_correct: core.
+
+Definition equiv_hsmem ge (hd1 hd2: hsmem) :=
+ (forall m, allvalid ge hd1.(hpre) m <-> allvalid ge hd2.(hpre) m)
+ /\ (forall m x, allvalid ge hd1.(hpre) m -> hsmem_post_eval ge hd1 x m = hsmem_post_eval ge hd2 x m).
+
+Lemma equiv_smem_symmetry ge hd1 hd2:
+ equiv_hsmem ge hd1 hd2 -> equiv_hsmem ge hd2 hd1.
+Proof.
+ intros (V1 & P1); split.
+ - intros; symmetry; auto.
+ - intros; symmetry; eapply P1. rewrite V1; auto.
+Qed.
+
+Lemma equiv_hsmem_models ge hd1 hd2 d:
+ smem_model ge d hd1 -> equiv_hsmem ge hd1 hd2 -> smem_model ge d hd2.
+Proof.
+ intros (VALID & EQUIV) (HEQUIV & PEQUIV); split.
+ - intros m; rewrite <- VALID; auto. symmetry; auto.
+ - intros m x H. rewrite <- EQUIV; auto.
+ rewrite PEQUIV; auto.
+ rewrite VALID; auto.
+Qed.
+
+Variable log_assign: R.t -> term -> ?? unit.
+
+Definition lift {A B} hid (x:A) (k: B -> ?? A) (y:B): ?? A :=
+ DO b <~ phys_eq hid unknown_hid;;
+ if b then k y else RET x.
+
+Fixpoint hterm_lift (t: term): ?? term :=
+ match t with
+ | Input x hid => lift hid t hInput x
+ | App o l hid =>
+ lift hid t
+ (fun l => DO lt <~ hlist_term_lift l;;
+ hApp o lt) l
+ end
+with hlist_term_lift (l: list_term) {struct l}: ?? list_term :=
+ match l with
+ | LTnil hid => lift hid l hLTnil ()
+ | LTcons t l' hid =>
+ lift hid l
+ (fun t => DO t <~ hterm_lift t;;
+ DO lt <~ hlist_term_lift l';;
+ hLTcons t lt) t
+ end.
+
+Lemma hterm_lift_correct t:
+ WHEN hterm_lift t ~> ht THEN forall ge m, term_eval ge ht m = term_eval ge t m.
+Proof.
+ induction t using term_mut with (P0:=fun lt =>
+ WHEN hlist_term_lift lt ~> hlt THEN forall ge m, list_term_eval ge hlt m = list_term_eval ge lt m);
+ wlp_simplify.
+ - rewrite H0, H; auto.
+ - rewrite H1, H0, H; auto.
+Qed.
+Local Hint Resolve hterm_lift_correct: wlp.
+Global Opaque hterm_lift.
+
+Variable log_new_hterm: term -> ?? unit.
+
+Fixpoint hterm_append (l: list term) (lh: list term): ?? list term :=
+ match l with
+ | nil => RET lh
+ | t::l' =>
+ DO ht <~ hterm_lift t;;
+ log_new_hterm ht;;
+ hterm_append l' (ht::lh)
+ end.
+
+Lemma hterm_append_correct l: forall lh,
+ WHEN hterm_append l lh ~> lh' THEN (forall ge m, allvalid ge lh' m <-> (allvalid ge l m /\ allvalid ge lh m)).
+Proof.
+ Local Hint Resolve eq_trans: localhint.
+ induction l as [|t l']; cbn; wlp_xsimplify ltac:(eauto with wlp).
+ - intros; rewrite! allvalid_extensionality; intuition eauto.
+ - intros REC ge m; rewrite REC; clear IHl' REC. rewrite !allvalid_extensionality.
+ cbn; intuition (subst; eauto with wlp localhint).
+Qed.
+(*Local Hint Resolve hterm_append_correct: wlp.*)
+Global Opaque hterm_append.
+
+Definition smart_set (hd:hsmem) x (ht:term) :=
+ match ht with
+ | Input y _ =>
+ if R.eq_dec x y then
+ RET (Dict.rem hd x)
+ else (
+ log_assign x ht;;
+ RET (Dict.set hd x ht)
+ )
+ | _ =>
+ log_assign x ht;;
+ RET (Dict.set hd x ht)
+ end.
+
+Lemma smart_set_correct hd x ht:
+ WHEN smart_set hd x ht ~> d THEN
+ forall ge m y, hsmem_post_eval ge d y m = hsmem_post_eval ge (Dict.set hd x ht) y m.
+Proof.
+ destruct ht; wlp_simplify.
+ unfold hsmem_post_eval; cbn. case (R.eq_dec x0 y).
+ - intros; subst. rewrite Dict.set_spec_eq, Dict.rem_spec_eq. cbn; congruence.
+ - intros; rewrite Dict.set_spec_diff, Dict.rem_spec_diff; auto.
+Qed.
+(*Local Hint Resolve smart_set_correct: wlp.*)
+Global Opaque smart_set.
+
+Definition hsmem_set (hd:hsmem) x (t:term) :=
+ DO pt <~ reduce t;;
+ DO lht <~ hterm_append pt.(mayfail) hd.(hpre);;
+ DO ht <~ hterm_lift pt.(effect);;
+ log_new_hterm ht;;
+ DO nd <~ smart_set hd x ht;;
+ RET {| hpre := lht; hpost := nd |}.
+
+Lemma hsmem_set_correct hd x ht:
+ WHEN hsmem_set hd x ht ~> nhd THEN
+ forall ge d t, smem_model ge d hd ->
+ (forall m, smem_valid ge d m -> term_eval ge ht m = ST.term_eval ge t m) ->
+ smem_model ge (smem_set d x t) nhd.
+Proof.
+ intros; wlp_simplify.
+ generalize (hterm_append_correct _ _ _ Hexta0); intro APPEND.
+ generalize (hterm_lift_correct _ _ Hexta1); intro LIFT.
+ generalize (smart_set_correct _ _ _ _ Hexta3); intro SMART.
+ eapply equiv_hsmem_models; eauto; unfold equiv_hsmem; cbn.
+ destruct H as (VALID & EFFECT); split.
+ - intros; rewrite APPEND, <- VALID.
+ rewrite !allvalid_extensionality in * |- *; cbn; intuition (subst; eauto).
+ - intros m x0 ALLVALID; rewrite SMART.
+ destruct (term_eval ge ht m) eqn: Hht.
+ * case (R.eq_dec x x0).
+ + intros; subst. unfold hsmem_post_eval; cbn. rewrite !Dict.set_spec_eq.
+ erewrite LIFT, EFFECT; eauto.
+ + intros; unfold hsmem_post_eval; cbn. rewrite !Dict.set_spec_diff; auto.
+ * rewrite allvalid_extensionality in ALLVALID; destruct (ALLVALID ht); cbn; auto.
+Qed.
+Local Hint Resolve hsmem_set_correct: wlp.
+Global Opaque hsmem_set.
+
+(* VARIANTE: we do not hash-cons the term from the expression
+Lemma exp_hterm_correct ge e hod od:
+ smem_model ge od hod ->
+ forall hd d,
+ smem_model ge d hd ->
+ forall m, smem_valid ge d m -> smem_valid ge od m -> term_eval ge (exp_term e hd hod) m = term_eval ge (exp_term e d od) m.
+Proof.
+ intro H.
+ induction e using exp_mut with (P0:=fun le => forall d hd,
+ smem_model ge d hd -> forall m, smem_valid ge d m -> smem_valid ge od m -> list_term_eval ge (list_exp_term le hd hod) m = list_term_eval ge (list_exp_term le d od) m);
+ unfold smem_model in * |- * ; cbn; intuition eauto.
+ - erewrite IHe; eauto.
+ - erewrite IHe0, IHe; eauto.
+Qed.
+Local Hint Resolve exp_hterm_correct: wlp.
+*)
+
+Fixpoint exp_hterm (e: exp) (hd hod: hsmem): ?? term :=
+ match e with
+ | PReg x => hsmem_get hd x
+ | Op o le =>
+ DO lt <~ list_exp_hterm le hd hod;;
+ hApp o lt
+ | Old e => exp_hterm e hod hod
+ end
+with list_exp_hterm (le: list_exp) (hd hod: hsmem): ?? list_term :=
+ match le with
+ | Enil => hLTnil tt
+ | Econs e le' =>
+ DO t <~ exp_hterm e hd hod;;
+ DO lt <~ list_exp_hterm le' hd hod;;
+ hLTcons t lt
+ | LOld le => list_exp_hterm le hod hod
+ end.
+
+Lemma exp_hterm_correct_x ge e hod od:
+ smem_model ge od hod ->
+ forall hd d,
+ smem_model ge d hd ->
+ WHEN exp_hterm e hd hod ~> t THEN forall m, smem_valid ge d m -> smem_valid ge od m -> term_eval ge t m = ST.term_eval ge (exp_term e d od) m.
+ Proof.
+ intro H.
+ induction e using exp_mut with (P0:=fun le => forall d hd,
+ smem_model ge d hd ->
+ WHEN list_exp_hterm le hd hod ~> lt THEN forall m, smem_valid ge d m -> smem_valid ge od m -> list_term_eval ge lt m = ST.list_term_eval ge (list_exp_term le d od) m);
+ unfold smem_model, hsmem_post_eval in * |- * ; cbn; wlp_simplify.
+ - rewrite H1, <- H4; auto.
+ - rewrite H4, <- H0; cbn; auto.
+ - rewrite H5, <- H0, <- H4; cbn; auto.
+Qed.
+Global Opaque exp_hterm.
+
+Lemma exp_hterm_correct e hd hod:
+ WHEN exp_hterm e hd hod ~> t THEN forall ge od d m, smem_model ge od hod -> smem_model ge d hd -> smem_valid ge d m -> smem_valid ge od m -> term_eval ge t m = ST.term_eval ge (exp_term e d od) m.
+Proof.
+ unfold wlp; intros; eapply exp_hterm_correct_x; eauto.
+Qed.
+Hint Resolve exp_hterm_correct: wlp.
+
+Fixpoint hinst_smem (i: inst) (hd hod: hsmem): ?? hsmem :=
+ match i with
+ | nil => RET hd
+ | (x, e)::i' =>
+ DO ht <~ exp_hterm e hd hod;;
+ DO nd <~ hsmem_set hd x ht;;
+ hinst_smem i' nd hod
+ end.
+
+Lemma hinst_smem_correct i: forall hd hod,
+ WHEN hinst_smem i hd hod ~> hd' THEN
+ forall ge od d, smem_model ge od hod -> smem_model ge d hd -> (forall m, smem_valid ge d m -> smem_valid ge od m) -> smem_model ge (inst_smem i d od) hd'.
+Proof.
+ Local Hint Resolve smem_valid_set_proof: core.
+ induction i; cbn; wlp_simplify; eauto 15 with wlp.
+Qed.
+Global Opaque hinst_smem.
+Local Hint Resolve hinst_smem_correct: wlp.
+
+(* logging info: we log the number of inst-instructions passed ! *)
+Variable log_new_inst: unit -> ?? unit.
+
+Fixpoint bblock_hsmem_rec (p: bblock) (d: hsmem): ?? hsmem :=
+ match p with
+ | nil => RET d
+ | i::p' =>
+ log_new_inst tt;;
+ DO d' <~ hinst_smem i d d;;
+ bblock_hsmem_rec p' d'
+ end.
+
+Lemma bblock_hsmem_rec_correct p: forall hd,
+ WHEN bblock_hsmem_rec p hd ~> hd' THEN forall ge d, smem_model ge d hd -> smem_model ge (bblock_smem_rec p d) hd'.
+Proof.
+ induction p; cbn; wlp_simplify.
+Qed.
+Global Opaque bblock_hsmem_rec.
+Local Hint Resolve bblock_hsmem_rec_correct: wlp.
+
+Definition hsmem_empty: hsmem := {| hpre:= nil ; hpost := Dict.empty |}.
+
+Lemma hsmem_empty_correct ge: smem_model ge smem_empty hsmem_empty.
+Proof.
+ unfold smem_model, smem_valid, hsmem_post_eval; cbn; intuition try congruence.
+ rewrite !Dict.empty_spec; cbn; auto.
+Qed.
+
+Definition bblock_hsmem: bblock -> ?? hsmem
+ := fun p => bblock_hsmem_rec p hsmem_empty.
+
+Lemma bblock_hsmem_correct p:
+ WHEN bblock_hsmem p ~> hd THEN forall ge, smem_model ge (bblock_smem p) hd.
+Proof.
+ Local Hint Resolve hsmem_empty_correct: core.
+ wlp_simplify.
+Qed.
+Global Opaque bblock_hsmem.
+
+End CanonBuilding.
+
+(* Now, we build the hash-Cons value from a "hash_eq".
+
+Informal specification:
+ [hash_eq] must be consistent with the "hashed" constructors defined above.
+
+We expect that hashinfo values in the code of these "hashed" constructors verify:
+
+ (hash_eq (hdata x) (hdata y) ~> true) <-> (hcodes x)=(hcodes y)
+
+*)
+
+Definition term_hash_eq (ta tb: term): ?? bool :=
+ match ta, tb with
+ | Input xa _, Input xb _ =>
+ if R.eq_dec xa xb (* Inefficient in some cases ? *)
+ then RET true
+ else RET false
+ | App oa lta _, App ob ltb _ =>
+ DO b <~ op_eq oa ob ;;
+ if b then phys_eq lta ltb
+ else RET false
+ | _,_ => RET false
+ end.
+
+Lemma term_hash_eq_correct: forall ta tb, WHEN term_hash_eq ta tb ~> b THEN b=true -> term_set_hid ta unknown_hid=term_set_hid tb unknown_hid.
+Proof.
+ Local Hint Resolve op_eq_correct: wlp.
+ destruct ta, tb; wlp_simplify; (discriminate || (subst; auto)).
+Qed.
+Global Opaque term_hash_eq.
+Hint Resolve term_hash_eq_correct: wlp.
+
+Definition list_term_hash_eq (lta ltb: list_term): ?? bool :=
+ match lta, ltb with
+ | LTnil _, LTnil _ => RET true
+ | LTcons ta lta _, LTcons tb ltb _ =>
+ DO b <~ phys_eq ta tb ;;
+ if b then phys_eq lta ltb
+ else RET false
+ | _,_ => RET false
+ end.
+
+Lemma list_term_hash_eq_correct: forall lta ltb, WHEN list_term_hash_eq lta ltb ~> b THEN b=true -> list_term_set_hid lta unknown_hid=list_term_set_hid ltb unknown_hid.
+Proof.
+ destruct lta, ltb; wlp_simplify; (discriminate || (subst; auto)).
+Qed.
+Global Opaque list_term_hash_eq.
+Hint Resolve list_term_hash_eq_correct: wlp.
+
+Lemma hsmem_post_eval_intro (d1 d2: hsmem):
+ (forall x, Dict.get d1 x = Dict.get d2 x) -> (forall ge x m, hsmem_post_eval ge d1 x m = hsmem_post_eval ge d2 x m).
+Proof.
+ unfold hsmem_post_eval; intros H ge x m; rewrite H. destruct (Dict.get d2 x); auto.
+Qed.
+
+Local Hint Resolve bblock_hsmem_correct Dict.eq_test_correct: wlp.
+
+Program Definition mk_hash_params (log: term -> ?? unit): Dict.hash_params term :=
+ {|
+ Dict.test_eq := phys_eq;
+ Dict.hashing := fun (ht: term) => RET (term_get_hid ht);
+ Dict.log := log |}.
+Obligation 1.
+ eauto with wlp.
+Qed.
+
+(*** A GENERIC EQ_TEST: IN ORDER TO SUPPORT SEVERAL DEBUGGING MODE !!! ***)
+Definition no_log_assign (x:R.t) (t:term): ?? unit := RET tt.
+Definition no_log_new_term (t:term): ?? unit := RET tt.
+
+Section Prog_Eq_Gen.
+
+Variable log_assign: R.t -> term -> ?? unit.
+Variable log_new_term: hashConsing term -> hashConsing list_term -> ??(term -> ?? unit).
+Variable log_inst1: unit -> ?? unit. (* log of p1 insts *)
+Variable log_inst2: unit -> ?? unit. (* log of p2 insts *)
+
+Variable hco_term: hashConsing term.
+Hypothesis hco_term_correct: forall t, WHEN hco_term.(hC) t ~> t' THEN forall ge m, term_eval ge (hdata t) m = term_eval ge t' m.
+
+Variable hco_list: hashConsing list_term.
+Hypothesis hco_list_correct: forall t, WHEN hco_list.(hC) t ~> t' THEN forall ge m, list_term_eval ge (hdata t) m = list_term_eval ge t' m.
+
+Variable print_end_error: hsmem -> hsmem -> ?? unit.
+Variable print_dump: (option pstring) -> ?? unit.
+
+Variable check_failpreserv: bool.
+Variable dbg_failpreserv: term -> ?? unit. (* info of additional failure of the output bbloc p2 wrt the input bbloc p1 *)
+
+Program Definition g_bblock_simu_test (p1 p2: bblock): ?? bool :=
+ DO failure_in_failpreserv <~ make_cref false;;
+ DO r <~ (TRY
+ DO d1 <~ bblock_hsmem hco_term.(hC) hco_list.(hC) log_assign no_log_new_term log_inst1 p1;;
+ DO log_new_term <~ log_new_term hco_term hco_list;;
+ DO d2 <~ bblock_hsmem hco_term.(hC) hco_list.(hC) no_log_assign log_new_term log_inst2 p2;;
+ DO b <~ Dict.eq_test d1 d2 ;;
+ if b then (
+ (if check_failpreserv then
+ let hp := mk_hash_params dbg_failpreserv in
+ failure_in_failpreserv.(set)(true);;
+ Sets.assert_list_incl hp d2.(hpre) d1.(hpre)
+ else RET tt);;
+ (if FULL_DEBUG_DUMP then
+ print_dump None (* not an error... *)
+ else RET tt);;
+ RET check_failpreserv
+ ) else (
+ print_end_error d1 d2 ;;
+ RET false
+ )
+ CATCH_FAIL s, _ =>
+ DO b <~ failure_in_failpreserv.(get)();;
+ if b then RET false
+ else print_dump (Some s);; RET false
+ ENSURE (fun b => b=true -> forall ge, bblock_simu ge p1 p2));;
+ RET (`r).
+Obligation 1.
+ constructor 1; wlp_simplify; try congruence.
+ destruct (H ge) as (EQPRE1&EQPOST1); destruct (H0 ge) as (EQPRE2&EQPOST2); clear H H0.
+ apply bblock_smem_simu; auto. split.
+ + intros m; rewrite <- EQPRE1, <- EQPRE2.
+ rewrite ! allvalid_extensionality.
+ unfold incl in * |- *; intuition eauto.
+ + intros m0 x VALID; rewrite <- EQPOST1, <- EQPOST2; auto.
+ erewrite hsmem_post_eval_intro; eauto.
+ erewrite <- EQPRE2; auto.
+ erewrite <- EQPRE1 in VALID.
+ rewrite ! allvalid_extensionality in * |- *.
+ unfold incl in * |- *; intuition eauto.
+Qed.
+
+Theorem g_bblock_simu_test_correct p1 p2:
+ WHEN g_bblock_simu_test p1 p2 ~> b THEN b=true -> forall ge, bblock_simu ge p1 p2.
+Proof.
+ wlp_simplify.
+ destruct exta0; cbn in * |- *; auto.
+Qed.
+Global Opaque g_bblock_simu_test.
+
+End Prog_Eq_Gen.
+
+
+
+Definition hpt: hashP term := {| hash_eq := term_hash_eq; get_hid:=term_get_hid; set_hid:=term_set_hid |}.
+Definition hplt: hashP list_term := {| hash_eq := list_term_hash_eq; get_hid:=list_term_get_hid; set_hid:=list_term_set_hid |}.
+
+Definition recover_hcodes (t:term): ??(hashinfo term) :=
+ match t with
+ | Input x _ =>
+ DO hv <~ hInput_hcodes x ;;
+ RET {| hdata := t; hcodes := hv |}
+ | App o l _ =>
+ DO hv <~ hApp_hcodes o l ;;
+ RET {| hdata := t; hcodes := hv |}
+ end.
+
+
+Definition msg_end_of_bblock: pstring :="--- unknown subterms in the graph".
+
+Definition log_new_term
+ (unknownHash_msg: term -> ?? pstring)
+ (hct:hashConsing term)
+ (hcl:hashConsing list_term)
+ : ?? (term -> ?? unit) :=
+ DO clock <~ hct.(next_hid)();;
+ hct.(next_log) msg_end_of_bblock;;
+ hcl.(next_log) msg_end_of_bblock;;
+ RET (fun t =>
+ DO ok <~ hash_older (term_get_hid t) clock;;
+ if ok
+ then
+ RET tt
+ else
+ DO ht <~ recover_hcodes t;;
+ hct.(remove) ht;;
+ DO msg <~ unknownHash_msg t;;
+ FAILWITH msg).
+
+Definition skip (_:unit): ?? unit := RET tt.
+
+Definition msg_prefix: pstring := "*** ERROR INFO from bblock_simu_test: ".
+Definition msg_error_on_end: pstring := "mismatch in final assignments !".
+Definition msg_unknow_term: pstring := "unknown term".
+Definition msg_number: pstring := "on 2nd bblock -- on inst num ".
+Definition msg_notfailpreserv: pstring := "a possible failure of 2nd bblock is absent in 1st bblock (INTERNAL ERROR: this error is expected to be detected before!!!)".
+
+Definition print_end_error (_ _: hsmem): ?? unit
+ := println (msg_prefix +; msg_error_on_end).
+
+Definition print_error (log: logger unit) (os: option pstring): ?? unit
+ := match os with
+ | Some s =>
+ DO n <~ log_info log ();;
+ println (msg_prefix +; msg_number +; n +; " -- " +; s)
+ | None => RET tt
+ end.
+
+Definition failpreserv_error (_: term): ?? unit
+ := println (msg_prefix +; msg_notfailpreserv).
+
+Lemma term_eval_set_hid_equiv ge t1 t2 hid1 hid2 m:
+ term_set_hid t1 hid1 = term_set_hid t2 hid2 -> term_eval ge t1 m = term_eval ge t2 m.
+Proof.
+ intro H; erewrite <- term_eval_set_hid; rewrite H. apply term_eval_set_hid.
+Qed.
+
+Lemma list_term_eval_set_hid_equiv ge t1 t2 hid1 hid2 m:
+ list_term_set_hid t1 hid1 = list_term_set_hid t2 hid2 -> list_term_eval ge t1 m = list_term_eval ge t2 m.
+Proof.
+ intro H; erewrite <- list_term_eval_set_hid; rewrite H. apply list_term_eval_set_hid.
+Qed.
+
+Local Hint Resolve term_eval_set_hid_equiv list_term_eval_set_hid_equiv: core.
+
+Program Definition bblock_simu_test (p1 p2: bblock): ?? bool :=
+ DO log <~ count_logger ();;
+ DO hco_term <~ mk_annot (hCons hpt);;
+ DO hco_list <~ mk_annot (hCons hplt);;
+ g_bblock_simu_test
+ no_log_assign
+ (log_new_term (fun _ => RET msg_unknow_term))
+ skip
+ (log_insert log)
+ hco_term _
+ hco_list _
+ print_end_error
+ (print_error log)
+ true (* check_failpreserv *)
+ failpreserv_error
+ p1 p2.
+Obligation 1.
+ generalize (hCons_correct _ _ _ H0); clear H0.
+ wlp_simplify.
+Qed.
+Obligation 2.
+ generalize (hCons_correct _ _ _ H); clear H.
+ wlp_simplify.
+Qed.
+
+Local Hint Resolve g_bblock_simu_test_correct: core.
+
+Theorem bblock_simu_test_correct p1 p2:
+ WHEN bblock_simu_test p1 p2 ~> b THEN b=true -> forall ge, bblock_simu ge p1 p2.
+Proof.
+ wlp_simplify.
+Qed.
+Global Opaque bblock_simu_test.
+
+(** This is only to print info on each bblock_simu_test run **)
+Section Verbose_version.
+
+Variable string_of_name: R.t -> ?? pstring.
+Variable string_of_op: op -> ?? pstring.
+
+
+Local Open Scope string_scope.
+
+Definition string_term_hid (t: term): ?? pstring :=
+ DO id <~ string_of_hashcode (term_get_hid t);;
+ RET ("E" +; (CamlStr id)).
+
+Definition string_list_hid (lt: list_term): ?? pstring :=
+ DO id <~ string_of_hashcode (list_term_get_hid lt);;
+ RET ("L" +; (CamlStr id)).
+
+Definition print_raw_term (t: term): ?? unit :=
+ match t with
+ | Input x _ =>
+ DO s <~ string_of_name x;;
+ println( "init_access " +; s)
+ | App o (LTnil _) _ =>
+ DO so <~ string_of_op o;;
+ println so
+ | App o l _ =>
+ DO so <~ string_of_op o;;
+ DO sl <~ string_list_hid l;;
+ println (so +; " " +; sl)
+ end.
+
+(*
+Definition print_raw_list(lt: list_term): ?? unit :=
+ match lt with
+ | LTnil _=> println ""
+ | LTcons t l _ =>
+ DO st <~ string_term_hid t;;
+ DO sl <~ string_list_hid l;;
+ println(st +; " " +; sl)
+ end.
+*)
+
+Section PrettryPrint.
+
+Variable get_debug_info: term -> ?? option pstring.
+
+Fixpoint string_of_term (t: term): ?? pstring :=
+ match t with
+ | Input x _ => string_of_name x
+ | App o (LTnil _) _ => string_of_op o
+ | App o l _ =>
+ DO so <~ string_of_op o;;
+ DO sl <~ string_of_list_term l;;
+ RET (so +; "[" +; sl +; "]")
+ end
+with string_of_list_term (l: list_term): ?? pstring :=
+ match l with
+ | LTnil _ => RET (Str "")
+ | LTcons t (LTnil _) _ =>
+ DO dbg <~ get_debug_info t;;
+ match dbg with
+ | Some x => RET x
+ | None => string_of_term t
+ end
+ | LTcons t l' _ =>
+ DO st <~ (DO dbg <~ get_debug_info t;;
+ match dbg with
+ | Some x => RET x
+ | None => string_of_term t
+ end);;
+ DO sl <~ string_of_list_term l';;
+ RET (st +; ";" +; sl)
+ end.
+
+End PrettryPrint.
+
+
+Definition pretty_term gdi t :=
+ DO r <~ string_of_term gdi t;;
+ println(r).
+
+Fixpoint print_head (head: list pstring): ?? unit :=
+ match head with
+ | i::head' => println (i);; print_head head'
+ | _ => RET tt
+ end.
+
+Definition print_term gdi (head: list pstring) (t: term): ?? unit :=
+ print_head head;;
+ DO s <~ string_term_hid t;;
+ print (s +; ": ");;
+ print_raw_term t;;
+ DO dbg <~ gdi t;;
+ match dbg with
+ | Some x =>
+ print("// " +; x +; " <- ");;
+ pretty_term gdi t
+ | None => RET tt
+ end.
+
+Definition print_list gdi (head: list pstring) (lt: list_term): ?? unit :=
+ print_head head;;
+ DO s <~ string_list_hid lt ;;
+ print (s +; ": ");;
+ (* print_raw_list lt;; *)
+ DO ps <~ string_of_list_term gdi lt;;
+ println("[" +; ps +; "]").
+
+
+Definition print_tables gdi ext exl: ?? unit :=
+ println "-- term table --" ;;
+ iterall ext (fun head _ pt => print_term gdi head pt.(hdata));;
+ println "-- list table --" ;;
+ iterall exl (fun head _ pl => print_list gdi head pl.(hdata));;
+ println "----------------".
+
+Definition print_final_debug gdi (d1 d2: hsmem): ?? unit
+ := DO b <~ Dict.not_eq_witness d1 d2 ;;
+ match b with
+ | Some x =>
+ DO s <~ string_of_name x;;
+ println("mismatch on: " +; s);;
+ match Dict.get d1 x with
+ | None => println("=> unassigned in 1st bblock")
+ | Some t1 =>
+ print("=> node expected from 1st bblock: ");;
+ pretty_term gdi t1
+ end;;
+ match Dict.get d2 x with
+ | None => println("=> unassigned in 2nd bblock")
+ | Some t2 =>
+ print("=> node found from 2nd bblock: ");;
+ pretty_term gdi t2
+ end
+ | None => FAILWITH "bug in Dict.not_eq_witness ?"
+ end.
+
+Definition witness:= option term.
+
+Definition msg_term (cr: cref witness) t :=
+ set cr (Some t);;
+ RET msg_unknow_term.
+
+Definition print_witness gdi cr (*msg*) :=
+ DO wit <~ get cr ();;
+ match wit with
+ | Some t =>
+ println("=> unknown term node: ");;
+ pretty_term gdi t (*;;
+ println("=> encoded on " +; msg +; " graph as: ");;
+ print_raw_term t *)
+ | None => println "Unexpected failure: no witness info (hint: hash-consing bug ?)"
+ end.
+
+Definition print_end_error1 gdi hct hcl (d1 d2:hsmem): ?? unit
+ := println "- GRAPH of 1st bblock";;
+ DO ext <~ export hct ();;
+ DO exl <~ export hcl ();;
+ print_tables gdi ext exl;;
+ print_end_error d1 d2;;
+ print_final_debug gdi d1 d2.
+
+Definition print_dump1 gdi hct hcl cr log os : ?? unit
+ := println "- GRAPH of 1st bblock";;
+ DO ext <~ export hct ();;
+ DO exl <~ export hcl ();;
+ print_tables gdi ext exl;;
+ print_error log os;;
+ match os with
+ | Some _ => print_witness gdi cr (*"1st"*)
+ | None => RET tt
+ end.
+
+Definition xmsg_number: pstring := "on 1st bblock -- on inst num ".
+
+Definition print_end_error2 gdi hct hcl (d1 d2:hsmem): ?? unit
+ := println (msg_prefix +; msg_error_on_end);;
+ println "- GRAPH of 2nd bblock";;
+ DO ext <~ export hct ();;
+ DO exl <~ export hcl ();;
+ print_tables gdi ext exl.
+
+Definition print_dump2 gdi hct hcl cr (log: logger unit) (os:option pstring): ?? unit
+ := DO n <~ log_info log ();;
+ DO ext <~ export hct ();;
+ DO exl <~ export hcl ();;
+ match os with
+ | Some s =>
+ println (msg_prefix +; xmsg_number +; n +; " -- " +; s);;
+ print_witness gdi cr (*"2nd"*)
+ | None => RET tt
+ end;;
+ println "- GRAPH of 2nd bblock";;
+ print_tables gdi ext exl.
+
+(* USELESS
+Definition simple_log_assign (d: D.t term pstring) (x: R.t) (t: term): ?? unit :=
+ DO s <~ string_of_name x;;
+ d.(D.set) (t,s).
+*)
+
+Definition log_assign (d: D.t term pstring) (log: logger unit) (x: R.t) (t: term): ?? unit :=
+ DO i <~ log_info log ();;
+ DO sx <~ string_of_name x;;
+ d.(D.set) (t,(sx +; "@" +; i)).
+
+Definition msg_new_inst : pstring := "--- inst ".
+
+Definition hlog (log: logger unit) (hct: hashConsing term) (hcl: hashConsing list_term): unit -> ?? unit :=
+ (fun _ =>
+ log_insert log tt ;;
+ DO s <~ log_info log tt;;
+ let s:= msg_new_inst +; s in
+ next_log hct s;;
+ next_log hcl s
+ ).
+
+Program Definition verb_bblock_simu_test (p1 p2: bblock): ?? bool :=
+ DO dict_info <~ make_dict (mk_hash_params (fun _ => RET tt));;
+ DO log1 <~ count_logger ();;
+ DO log2 <~ count_logger ();;
+ DO cr <~ make_cref None;;
+ DO hco_term <~ mk_annot (hCons hpt);;
+ DO hco_list <~ mk_annot (hCons hplt);;
+ (if FULL_DEBUG_DUMP then
+ println("");;
+ println("-- START simu checker --")
+ else RET tt);;
+ DO result1 <~ (g_bblock_simu_test
+ (log_assign dict_info log1)
+ (log_new_term (msg_term cr))
+ (hlog log1 hco_term hco_list)
+ (log_insert log2)
+ hco_term _
+ hco_list _
+ (print_end_error1 dict_info.(D.get) hco_term hco_list)
+ (print_dump1 dict_info.(D.get) hco_term hco_list cr log2)
+ true
+ failpreserv_error
+ p1 p2);;
+ if (if FULL_DEBUG_DUMP then false else result1)
+ then RET true
+ else (
+ DO dict_info <~ make_dict (mk_hash_params (fun _ => RET tt));;
+ DO log1 <~ count_logger ();;
+ DO log2 <~ count_logger ();;
+ DO cr <~ make_cref None;;
+ DO hco_term <~ mk_annot (hCons hpt);;
+ DO hco_list <~ mk_annot (hCons hplt);;
+ DO result2 <~ g_bblock_simu_test
+ (log_assign dict_info log1)
+ (*fun _ _ => RET no_log_new_term*) (* REM: too weak !! *)
+ (log_new_term (msg_term cr)) (* REM: too strong ?? *)
+ (hlog log1 hco_term hco_list)
+ (log_insert log2)
+ hco_term _
+ hco_list _
+ (print_end_error2 dict_info.(D.get) hco_term hco_list)
+ (print_dump2 dict_info.(D.get) hco_term hco_list cr log2)
+ false
+ (fun _ => RET tt)
+ p2 p1;;
+ if FULL_DEBUG_DUMP then
+ println("-- END simu checker --");;
+ println("");;
+ RET result1
+ else if result2
+ then (
+ println (msg_prefix +; " OOops - symmetry violation in bblock_simu_test => this is a bug of bblock_simu_test ??");;
+ RET false
+ ) else RET false
+ ).
+Obligation 1.
+ generalize (hCons_correct _ _ _ H1); clear H1.
+ wlp_simplify.
+Qed.
+Obligation 2.
+ generalize (hCons_correct _ _ _ H0); clear H0.
+ wlp_simplify.
+Qed.
+Obligation 3.
+ generalize (hCons_correct _ _ _ H1); clear H1.
+ wlp_simplify.
+Qed.
+Obligation 4.
+ generalize (hCons_correct _ _ _ H0); clear H0.
+ wlp_simplify.
+Qed.
+
+Theorem verb_bblock_simu_test_correct p1 p2:
+ WHEN verb_bblock_simu_test p1 p2 ~> b THEN b=true -> forall ge, bblock_simu ge p1 p2.
+Proof.
+ wlp_simplify.
+Qed.
+Global Opaque verb_bblock_simu_test.
+
+End Verbose_version.
+
+End SimuWithReduce.
+
+(* TODO: why inlining fails here ? *)
+Transparent hterm_lift.
+Extraction Inline lift.
+
+End ImpSimu.
+
+
+(** * Implementation of the Dictionary (based on PositiveMap) *)
+Require Import FMapPositive.
+Require Import PArith.
+Require Import FMapPositive.
+
+Module ImpPosDict <: ImpDict with Module R:=Pos.
+
+Module R:=Pos.
+
+Definition t:=PositiveMap.t.
+
+Definition get {A} (d:t A) (x:R.t): option A
+ := PositiveMap.find x d.
+
+Definition set {A} (d:t A) (x:R.t) (v:A): t A
+ := PositiveMap.add x v d.
+
+Local Hint Unfold PositiveMap.E.eq: core.
+
+Lemma set_spec_eq A d x (v: A):
+ get (set d x v) x = Some v.
+Proof.
+ unfold get, set; apply PositiveMap.add_1; auto.
+Qed.
+
+Lemma set_spec_diff A d x y (v: A):
+ x <> y -> get (set d x v) y = get d y.
+Proof.
+ unfold get, set; intros; apply PositiveMap.gso; auto.
+Qed.
+
+Definition rem {A} (d:t A) (x:R.t): t A
+ := PositiveMap.remove x d.
+
+Lemma rem_spec_eq A (d: t A) x:
+ get (rem d x) x = None.
+Proof.
+ unfold get, rem; apply PositiveMap.grs; auto.
+Qed.
+
+Lemma rem_spec_diff A (d: t A) x y:
+ x <> y -> get (rem d x) y = get d y.
+Proof.
+ unfold get, rem; intros; apply PositiveMap.gro; auto.
+Qed.
+
+
+Definition empty {A}: t A := PositiveMap.empty A.
+
+Lemma empty_spec A x:
+ get (empty (A:=A)) x = None.
+Proof.
+ unfold get, empty; apply PositiveMap.gempty; auto.
+Qed.
+
+Import PositiveMap.
+
+Fixpoint eq_test {A} (d1 d2: t A): ?? bool :=
+ match d1, d2 with
+ | Leaf _, Leaf _ => RET true
+ | Node l1 (Some x1) r1, Node l2 (Some x2) r2 =>
+ DO b0 <~ phys_eq x1 x2 ;;
+ if b0 then
+ DO b1 <~ eq_test l1 l2 ;;
+ if b1 then
+ eq_test r1 r2
+ else
+ RET false
+ else
+ RET false
+ | Node l1 None r1, Node l2 None r2 =>
+ DO b1 <~ eq_test l1 l2 ;;
+ if b1 then
+ eq_test r1 r2
+ else
+ RET false
+ | _, _ => RET false
+ end.
+
+Lemma eq_test_correct A d1: forall (d2: t A),
+ WHEN eq_test d1 d2 ~> b THEN
+ b=true -> forall x, get d1 x = get d2 x.
+Proof.
+ unfold get; induction d1 as [|l1 Hl1 [x1|] r1 Hr1]; destruct d2 as [|l2 [x2|] r2]; cbn;
+ wlp_simplify; (discriminate || (subst; destruct x; cbn; auto)).
+Qed.
+Global Opaque eq_test.
+
+(** ONLY FOR DEBUGGING INFO: get some key of a non-empty d *)
+Fixpoint pick {A} (d: t A): ?? R.t :=
+ match d with
+ | Leaf _ => FAILWITH "unexpected empty dictionary"
+ | Node _ (Some _) _ => RET xH
+ | Node (Leaf _) None r =>
+ DO p <~ pick r;;
+ RET (xI p)
+ | Node l None _ =>
+ DO p <~ pick l;;
+ RET (xO p)
+ end.
+
+(** ONLY FOR DEBUGGING INFO: find one variable on which d1 and d2 differs *)
+Fixpoint not_eq_witness {A} (d1 d2: t A): ?? option R.t :=
+ match d1, d2 with
+ | Leaf _, Leaf _ => RET None
+ | Node l1 (Some x1) r1, Node l2 (Some x2) r2 =>
+ DO b0 <~ phys_eq x1 x2 ;;
+ if b0 then
+ DO b1 <~ not_eq_witness l1 l2;;
+ match b1 with
+ | None =>
+ DO b2 <~ not_eq_witness r1 r2;;
+ match b2 with
+ | None => RET None
+ | Some p => RET (Some (xI p))
+ end
+ | Some p => RET (Some (xO p))
+ end
+ else
+ RET (Some xH)
+ | Node l1 None r1, Node l2 None r2 =>
+ DO b1 <~ not_eq_witness l1 l2;;
+ match b1 with
+ | None =>
+ DO b2 <~ not_eq_witness r1 r2;;
+ match b2 with
+ | None => RET None
+ | Some p => RET (Some (xI p))
+ end
+ | Some p => RET (Some (xO p))
+ end
+ | l, Leaf _ => DO p <~ pick l;; RET (Some p)
+ | Leaf _, r => DO p <~ pick r;; RET (Some p)
+ | _, _ => RET (Some xH)
+ end.
+
+End ImpPosDict.
+