Library iris.heap_lang.heap

From iris.heap_lang Require Export lifting.
From iris.algebra Require Import upred_big_op frac dec_agree.
From iris.program_logic Require Export invariants ghost_ownership.
From iris.program_logic Require Import ownership auth.
From iris.proofmode Require Import weakestpre.
Import uPred.

Definition heapN : namespace := nroot .@ "heap".
Definition heapUR : ucmraT := gmapUR loc (prodR fracR (dec_agreeR val)).

The CMRA we need.
Class heapG Σ := HeapG {
  heap_inG :> authG heap_lang Σ heapUR;
  heap_name : gname
}.
The Functor we need.
Definition heapGF : gFunctor := authGF heapUR.

Definition to_heap : state heapUR := fmap (λ v, (1%Qp, DecAgree v)).
Definition of_heap : heapUR state := omap (maybe DecAgree snd).

Section definitions.
  Context `{heapG Σ}.

  Definition heap_mapsto_def (l : loc) (q : Qp) (v: val) : iPropG heap_lang Σ :=
    auth_own heap_name {[ l := (q, DecAgree v) ]}.
  Definition heap_mapsto_aux : { x | x = @heap_mapsto_def }. by eexists. Qed.
  Definition heap_mapsto := proj1_sig heap_mapsto_aux.
  Definition heap_mapsto_eq : @heap_mapsto = @heap_mapsto_def :=
    proj2_sig heap_mapsto_aux.

  Definition heap_inv (h : heapUR) : iPropG heap_lang Σ :=
    ownP (of_heap h).
  Definition heap_ctx : iPropG heap_lang Σ :=
    auth_ctx heap_name heapN heap_inv.

  Global Instance heap_inv_proper : Proper ((≡) ==> (⊣⊢)) heap_inv.
  Proof. solve_proper. Qed.
  Global Instance heap_ctx_relevant : RelevantP heap_ctx.
  Proof. apply _. Qed.
  Global Instance heap_ctx_affine : AffineP heap_ctx.
  Proof. apply _. Qed.
End definitions.

Typeclasses Opaque heap_ctx heap_mapsto.
Instance: Params (@heap_inv) 1.
Instance: Params (@heap_mapsto) 4.
Instance: Params (@heap_ctx) 2.

Notation "l ↦{ q } v" := (heap_mapsto l q v)
  (at level 20, q at level 50, format "l ↦{ q } v") : uPred_scope.
Notation "l ↦ v" := (heap_mapsto l 1 v) (at level 20) : uPred_scope.

Section heap.
  Context {Σ : gFunctors}.
  Implicit Types P Q : iPropG heap_lang Σ.
  Implicit Types Φ : val iPropG heap_lang Σ.
  Implicit Types σ : state.
  Implicit Types h g : heapUR.

Conversion to heaps and back
  Global Instance of_heap_proper : Proper ((≡) ==> (=)) of_heap.
  Proof. solve_proper. Qed.
  Lemma from_to_heap σ : of_heap (to_heap σ) = σ.
  Proof.
    apply map_eql. rewrite lookup_omap lookup_fmap. by case!! l).
  Qed.
  Lemma to_heap_valid σ : to_heap σ.
  Proof. intros l. rewrite lookup_fmap. by case!! l). Qed.
  Lemma of_heap_insert l v h :
    of_heap (<[l:=(1%Qp, DecAgree v)]> h) = <[l:=v]> (of_heap h).
  Proof. by rewrite /of_heap -(omap_insert _ _ _ (1%Qp, DecAgree v)). Qed.
  Lemma of_heap_singleton_op l q v h :
     ({[l := (q, DecAgree v)]} h)
    of_heap ({[l := (q, DecAgree v)]} h) = <[l:=v]> (of_heap h).
  Proof.
    intros Hv. apply map_eql'; destruct (decide (l' = l)) as [->|].
    - move: (Hv l). rewrite /of_heap lookup_insert
        lookup_omap (lookup_op _ h) lookup_singleton.
      case _:(h !! l)=>[[q' [v'|]]|] //=; last by move⇒ [??].
      move⇒ [? /dec_agree_op_inv [->]]. by rewrite dec_agree_idemp.
    - rewrite /of_heap lookup_insert_ne // !lookup_omap.
      by rewrite (lookup_op _ h) lookup_singleton_ne // left_id_L.
  Qed.
  Lemma to_heap_insert l v σ :
    to_heap (<[l:=v]> σ) = <[l:=(1%Qp, DecAgree v)]> (to_heap σ).
  Proof. by rewrite /to_heap -fmap_insert. Qed.
  Lemma of_heap_None h l : h of_heap h !! l = None h !! l = None.
  Proof.
    move⇒ /(_ l). rewrite /of_heap lookup_omap.
    by case: (h !! l)=> [[q [v|]]|] //=; destruct 1; auto.
  Qed.
  Lemma heap_store_valid l h v1 v2 :
     ({[l := (1%Qp, DecAgree v1)]} h)
     ({[l := (1%Qp, DecAgree v2)]} h).
  Proof.
    intros Hv l'; move: (Hv l'). destruct (decide (l' = l)) as [->|].
    - rewrite !lookup_op !lookup_singleton.
      by case: (h !! l)=> [x|] // /Some_valid/exclusive_l.
    - by rewrite !lookup_op !lookup_singleton_ne.
  Qed.
  Hint Resolve heap_store_valid.

Allocation
  Lemma heap_alloc E σ :
    authG heap_lang Σ heapUR nclose heapN E
    ownP σ ={E}=> _ : heapG Σ, heap_ctx [★ map] lv σ, l v.
  Proof.
    intros. rewrite -{1}(from_to_heap σ). etrans.
    {rewrite [ownP _](affine_intro _ (ownP (of_heap (to_heap σ)))); last auto.
      rewrite [ownP _]later_intro.
      apply (auth_alloc (ownP of_heap) heapN E); auto using to_heap_valid. }
    apply pvs_mono, exist_elimγ.
    rewrite -(exist_intro (HeapG _ _ γ)) /heap_ctx. apply sep_mono_r.
    rewrite heap_mapsto_eq /heap_mapsto_def /heap_name.
    induction σ as [|l v σ Hl IH] using map_ind.
    { rewrite big_sepM_empty. rewrite emp_True.
      rewrite /auth_own. apply affine_intro; first apply _; auto. }
    rewrite to_heap_insert big_sepM_insert //.
    rewrite (insert_singleton_op (to_heap σ));
      last by rewrite lookup_fmap Hl; auto.
    by rewrite auth_own_op IH.
  Qed.

  Context `{heapG Σ}.

General properties of mapsto
  Global Instance heap_mapsto_timeless l q v : ATimelessP (l ↦{q} v).
  Proof. rewrite heap_mapsto_eq /heap_mapsto_def. apply _. Qed.
  Global Instance heap_mapsto_affine l q v : AffineP (l ↦{q} v).
  Proof. rewrite heap_mapsto_eq /heap_mapsto_def. apply _. Qed.
  Global Instance heap_mapsto_map_affine σ:
    AffineP ([★ map] lv σ, l v)%I.
  Proof.
    intros; apply big_sep_affine.
    rewrite /AffineL. induction map_to_list as [| a ?]; simpl; eauto using nil_affine.
    destruct a; simpl; apply cons_affine; eauto using heap_mapsto_affine.
  Qed.

  Lemma heap_mapsto_op_eq l q1 q2 v : (l ↦{q1} v l ↦{q2} v) ⊣⊢ l ↦{q1+q2} v.
  Proof. by rewrite heap_mapsto_eq -auth_own_op op_singleton pair_op dec_agree_idemp. Qed.

  Lemma heap_mapsto_op l q1 q2 v1 v2 :
    (l ↦{q1} v1 l ↦{q2} v2) ⊣⊢ ( (v1 = v2) l ↦{q1+q2} v1).
  Proof.
    destruct (decide (v1 = v2)) as [->|].
    { by rewrite heap_mapsto_op_eq pure_equiv // -emp_True left_id. }
    rewrite heap_mapsto_eq -auth_own_op op_singleton pair_op dec_agree_ne //.
    apply (anti_symm (⊢)); last by apply pure_elim_sep_l.
    rewrite auth_own_valid gmap_validI (forall_elim l) lookup_singleton.
    rewrite option_validI prod_validI frac_validI discrete_valid.
    rewrite affine_and comm affine_elim comm.
    by apply pure_elim_r.
  Qed.

  Lemma heap_mapsto_op_split l q v : l ↦{q} v ⊣⊢ (l ↦{q/2} v l ↦{q/2} v).
  Proof. by rewrite heap_mapsto_op_eq Qp_div_2. Qed.

Weakest precondition
  Lemma wp_alloc E e v Φ :
    to_val e = Some v nclose heapN E
    (heap_ctx l, l v -★ |={E heapN}=>> Φ (LitV $ LitLoc l)) WP Alloc e @ E {{ Φ }}.
  Proof.
    iIntros (<-%of_to_val ?) "[#Hinv HΦ]". rewrite /heap_ctx.
    iPvs (auth_empty heap_name) as "Hheap".
    iApply wp_pvs; iApply (auth_afsa_alt heap_inv (wp_fsa _)); eauto with fsaV.
    iFrame "Hinv". iSplitL "Hheap"; first (iIntros "@"; by iNext).
    iIntros (h). rewrite left_id.
    iIntros "[% Hheap]". rewrite /heap_inv.
    pose (l := fresh (dom _ (of_heap h))).
    iExists {[ l := (1%Qp, DecAgree v) ]}.
    rewrite -(insert_singleton_op h);
      last by (apply of_heap_None, (not_elem_of_dom (D:= gset _)), is_fresh).
    iSplitL "".
    { iPureIntro. apply alloc_unit_singleton_local_update; last done.
      by apply of_heap_None, (not_elem_of_dom (D:= gset _)), is_fresh; eauto. }
    iIntros "Hauth".
    iApply wp_alloc_pst'. iFrame "Hheap". iNext.
    iIntros "Hheap".
    rewrite -of_heap_insert.
    rewrite -{1}(affine_affine (ownP _)) {1}(later_intro (ownP _)).
    iFrame "Hheap".
    iSpecialize ("HΦ" $! l). rewrite -(pvs_intro).
    iApply "HΦ". by rewrite heap_mapsto_eq /heap_mapsto_def.
  Qed.

  Lemma wp_load E l q v Φ :
    nclose heapN E
    (heap_ctx l ↦{q} v ▷( l ↦{q} v -★ |={E heapN}=>> (Φ v)))
     WP Load (Lit (LitLoc l)) @ E {{ Φ }}.
  Proof.
    iIntros (?) "[#Hh [Hl HΦ]]".
    rewrite /heap_ctx heap_mapsto_eq /heap_mapsto_def.
    iApply wp_pvs; iApply (auth_afsa_alt heap_inv (wp_fsa _)); eauto with fsaV.
    iFrame "Hh Hl". iIntros (h) "[% Hl]". rewrite /heap_inv.
    iExists _.
    iSplitL "".
    { iPureIntro. reflexivity. }
    iIntros "Hauth".
    iApply (wp_load_pst _ (<[l:=v]>(of_heap h)));first by rewrite lookup_insert.
    rewrite of_heap_singleton_op //. iFrame "Hl".
    iIntros "> Hown".
    rewrite -{1}(affine_affine (ownP _)).
    rewrite {1}(later_intro (ownP _)).
    iFrame "Hown". rewrite -pvs_intro. iApply "HΦ".
    by iIntros "@".
  Qed.

  Lemma wp_store E l v' e v Φ :
    to_val e = Some v nclose heapN E
    (heap_ctx l v' (l v -★ |={E heapN}=>> ( Φ (LitV LitUnit))))
     WP Store (Lit (LitLoc l)) e @ E {{ Φ }}.
  Proof.
    iIntros (<-%of_to_val ?) "[#Hh [Hl HΦ]]".
    rewrite /heap_ctx heap_mapsto_eq /heap_mapsto_def.
    iApply wp_pvs; iApply (auth_afsa_alt heap_inv (wp_fsa _)); eauto with fsaV.
    iFrame "Hh Hl". iIntros (h) "[% Hl]". rewrite /heap_inv.
    iExists {[ l := (1%Qp, DecAgree v) ]}.
    iSplitL "".
    { iPureIntro; by apply singleton_local_update, exclusive_local_update. }
    iIntros "Hauth".
    iApply (wp_store_pst _ (<[l:=v']>(of_heap h))); eauto; first by rewrite lookup_insert.
    rewrite of_heap_singleton_op //. iFrame "Hl".
    iIntros "> Hown".
    rewrite -{1}(affine_affine (ownP _)).
    rewrite {1}(later_intro (ownP _)).
    rewrite insert_insert !of_heap_singleton_op; eauto.
    iFrame "Hown". rewrite -pvs_intro. by iApply "HΦ".
  Qed.

  Lemma wp_cas_fail E l q v' e1 v1 e2 v2 Φ :
    to_val e1 = Some v1 to_val e2 = Some v2 v' v1 nclose heapN E
    heap_ctx l ↦{q} v' (l ↦{q} v' -★ |={E heapN}=>> Φ (LitV (LitBool false)))
     WP CAS (Lit (LitLoc l)) e1 e2 @ E {{ Φ }}.
  Proof.
    iIntros (<-%of_to_val <-%of_to_val ??) "[#Hh [Hl HΦ]]".
    rewrite /heap_ctx heap_mapsto_eq /heap_mapsto_def.
    iApply (auth_afsa_alt heap_inv (wp_fsa _)); eauto with fsaV.
    iFrame "Hh Hl". iIntros (h) "[% Hl]". rewrite /heap_inv.
    iExists {[ l := (q, DecAgree v') ]}.
    iSplitL "".
    { iPureIntro; naive_solver. }
    iIntros "Hauth".
    iApply (wp_cas_fail_pst _ (<[l:=v']>(of_heap h))); rewrite ?lookup_insert //.
    rewrite of_heap_singleton_op //. iFrame "Hl". iNext.
    iIntros "HownP".
    rewrite -{1}(affine_affine (ownP _)).
    rewrite {1}(later_intro (ownP _)).
    iFrame "HownP". iApply "HΦ"; done.
  Qed.

  Lemma wp_cas_suc E l e1 v1 e2 v2 Φ :
    to_val e1 = Some v1 to_val e2 = Some v2 nclose heapN E
    heap_ctx l v1 (l v2 -★ |={E heapN}=>> (Φ (LitV (LitBool true))))
     WP CAS (Lit (LitLoc l)) e1 e2 @ E {{ Φ }}.
  Proof.
    iIntros (<-%of_to_val <-%of_to_val ?) "[#Hh [Hl HΦ]]".
    rewrite /heap_ctx heap_mapsto_eq /heap_mapsto_def.
    iApply (auth_afsa_alt heap_inv (wp_fsa _)); eauto with fsaV.
    iFrame "Hh Hl". iIntros (h) "[% Hl]". rewrite /heap_inv.
    iExists {[ l := (1%Qp, DecAgree v2) ]}.
    iSplitL "".
    { iPureIntro; by apply singleton_local_update, exclusive_local_update. }
    iIntros "Hauth".
    iApply (wp_cas_suc_pst _ (<[l:=v1]>(of_heap h))); rewrite ?lookup_insert //.
    rewrite insert_insert !of_heap_singleton_op; eauto.
    iFrame "Hl". iNext.
    iIntros "HownP".
    rewrite -{1}(affine_affine (ownP _)).
    rewrite {1}(later_intro (ownP _)).
    iFrame "HownP".
    iApply psvs_mono; last auto. iIntros "$"; auto.
    iApply ("HΦ"); done.
  Qed.

  Lemma wp_swap E l v e v' Φ :
    to_val e = Some v' nclose heapN E
    heap_ctx l v (l v' -★ |={E heapN}=>> (Φ v))
     WP Swap (Lit (LitLoc l)) e @ E {{ Φ }}.
  Proof.
    iIntros (<-%of_to_val ?) "[#Hh [Hl HΦ]]".
    rewrite /heap_ctx heap_mapsto_eq /heap_mapsto_def.
    iApply (auth_afsa_alt heap_inv (wp_fsa _)); eauto with fsaV.
    iFrame "Hh Hl". iIntros (h) "[% Hl]". rewrite /heap_inv.
    iExists {[ l := (1%Qp, DecAgree v') ]}.
    iSplitL "".
    { iPureIntro; by apply singleton_local_update, exclusive_local_update. }
    iIntros "Hauth".
    iApply (wp_swap_pst _ (<[l:=v]>(of_heap h))); rewrite ?lookup_insert //.
    rewrite insert_insert !of_heap_singleton_op; eauto.
    iFrame "Hl". iNext.
    iIntros "HownP".
    rewrite -{1}(affine_affine (ownP _)).
    rewrite {1}(later_intro (ownP _)).
    iFrame "HownP".
    iApply psvs_mono; last auto. iIntros "$"; auto.
    iApply ("HΦ"); done.
  Qed.

  Lemma wp_fai E l k Φ :
    nclose heapN E
    heap_ctx l (LitV $ LitInt k)
              (l (LitV $ LitInt (k+1)) -★ |={E heapN}=>> (Φ (LitV $ LitInt k)))
     WP FAI (Lit (LitLoc l)) @ E {{ Φ }}.
  Proof.
    iIntros (?) "[#Hh [Hl HΦ]]".
    rewrite /heap_ctx heap_mapsto_eq /heap_mapsto_def.
    iApply (auth_afsa_alt heap_inv (wp_fsa _)); eauto with fsaV.
    iFrame "Hh Hl". iIntros (h) "[% Hl]". rewrite /heap_inv.
    iExists {[ l := (1%Qp, DecAgree (LitV $ LitInt (k+1))) ]}.
    iSplitL "".
    { iPureIntro; by apply singleton_local_update, exclusive_local_update. }
    iIntros "Hauth".
    iApply (wp_fai_pst _ (<[l:=LitV $ LitInt k]>(of_heap h))); rewrite ?lookup_insert //.
    rewrite insert_insert !of_heap_singleton_op; eauto.
    iFrame "Hl". iNext.
    iIntros "HownP".
    rewrite -{1}(affine_affine (ownP _)).
    rewrite {1}(later_intro (ownP _)).
    iFrame "HownP".
    iApply psvs_mono; last auto. iIntros "$"; auto.
    iApply ("HΦ"); done.
  Qed.

End heap.