Commit eb5b9b57 authored by Zhen Zhang's avatar Zhen Zhang
Browse files

Merge branch 'atomic' into 'master'

unfolded logically atomic triple

The definition is a bit funky now to hack together something fast. See demo section for an example of application.

cc @dreyer @jung @robbertkrebbers @jjourdan 

See merge request !7
parents f2450784 f6078a30
......@@ -104,6 +104,7 @@ heap_lang/lib/barrier/protocol.v
From iris.program_logic Require Export hoare weakestpre.
From iris.program_logic Require Export pviewshifts.
From iris.program_logic Require Import ownership.
From iris.algebra Require Import upred_big_op.
From iris.prelude Require Export coPset.
From iris.proofmode Require Import tactics pviewshifts weakestpre.
Import uPred.
Section atomic.
Context `{irisG Λ Σ}.
(* <x, α> e @ E_i, E_o <v, β x v> *)
Definition atomic_triple {A: Type}
(α: A iProp Σ)
(β: A val _ iProp Σ)
(Ei Eo: coPset)
(e: expr _) : iProp Σ :=
( P Q, (P ={Eo, Ei}=> x:A,
α x
((α x ={Ei, Eo}= P)
( v, β x v ={Ei, Eo}= Q x v))
) - {{ P }} e @ {{ v, ( x: A, Q x v) }})%I.
Arguments atomic_triple {_} _ _ _ _ _.
End atomic.
From iris.heap_lang Require Export lang.
From iris.proofmode Require Import invariants tactics.
From iris.heap_lang Require Import proofmode notation.
Section demo.
Context `{!heapG Σ} (N : namespace).
Definition incr: val :=
rec: "incr" "l" :=
let: "oldv" := !"l" in
if: CAS "l" "oldv" ("oldv" + #1)
then "oldv" (* return old value if success *)
else "incr" "l".
Global Opaque incr.
(* TODO: Can we have a more WP-style definition and avoid the equality? *)
Definition incr_triple (l: loc) :=
atomic_triple (fun (v: Z) => l #v)%I
(fun v ret => ret = #v l #(v + 1))%I
(nclose heapN)
(incr #l).
Lemma incr_atomic_spec: (l: loc), heapN N heap_ctx incr_triple l.
iIntros (l HN) "#?".
rewrite /incr_triple.
rewrite /atomic_triple.
iIntros (P Q) "#Hvs".
iLöb as "IH".
iIntros "!# HP".
wp_bind (! _)%E.
iVs ("Hvs" with "HP") as (x) "[Hl [Hvs' _]]".
iVs ("Hvs'" with "Hl") as "HP".
iVsIntro. wp_let. wp_bind (CAS _ _ _). wp_op.
(* iVs ("Hvs" with "HP") as (x) "[Hl Hvs']". (* FIXME: Can't apply, bug? *) *)
iApply (wp_atomic heapN _); first by solve_atomic.
iVs ("Hvs" with "HP") as (x') "[Hl Hvs']".
destruct (decide (x = x')).
- subst.
iDestruct "Hvs'" as "[_ Hvs']".
iSpecialize ("Hvs'" $! #x').
iVs ("Hvs'" with "[Hl]") as "HQ"; first by iFrame.
iVsIntro. wp_if. iVsIntro. by iExists x'.
- iDestruct "Hvs'" as "[Hvs' _]".
iVsIntro. wp_cas_fail.
iVs ("Hvs'" with "[Hl]") as "HP"; first by iFrame.
iVsIntro. wp_if. by iApply "IH".
End demo.
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