From: Brian Norris <banorris@uci.edu>
Date: Wed, 8 May 2013 17:09:52 +0000 (-0700)
Subject: execution: bugfix - resolved promises should propagate synchronization
X-Git-Tag: oopsla2013~11
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=model-checker.git;a=commitdiff_plain;h=741d3d1160343d8545a783a2d05d3d0562b1c737

execution: bugfix - resolved promises should propagate synchronization

A new write ModelAction may resolve a Promise, completing a release
sequence and updating the read's clock vector. This update should be
propagated to any ModelAction later in the execution order which had
previously "happened after" the read.
---

diff --git a/execution.cc b/execution.cc
index 4e15427..4496b9c 100644
--- a/execution.cc
+++ b/execution.cc
@@ -817,9 +817,10 @@ void ModelExecution::add_future_value(const ModelAction *writer, ModelAction *re
 /**
  * Process a write ModelAction
  * @param curr The ModelAction to process
+ * @param work The work queue, for adding fixup work
  * @return True if the mo_graph was updated or promises were resolved
  */
-bool ModelExecution::process_write(ModelAction *curr)
+bool ModelExecution::process_write(ModelAction *curr, work_queue_t *work)
 {
 	/* Readers to which we may send our future value */
 	ModelVector<ModelAction *> send_fv;
@@ -832,7 +833,7 @@ bool ModelExecution::process_write(ModelAction *curr)
 
 	if (promise) {
 		earliest_promise_reader = promise->get_reader(0);
-		updated_promises = resolve_promise(curr, promise);
+		updated_promises = resolve_promise(curr, promise, work);
 	} else
 		earliest_promise_reader = NULL;
 
@@ -1272,7 +1273,7 @@ ModelAction * ModelExecution::check_current_action(ModelAction *curr)
 			if (act->is_read() && !second_part_of_rmw && process_read(act))
 				update = true;
 
-			if (act->is_write() && process_write(act))
+			if (act->is_write() && process_write(act, &work_queue))
 				update = true;
 
 			if (act->is_fence() && process_fence(act))
@@ -2333,15 +2334,20 @@ Promise * ModelExecution::pop_promise_to_resolve(const ModelAction *curr)
  * Resolve a Promise with a current write.
  * @param write The ModelAction that is fulfilling Promises
  * @param promise The Promise to resolve
+ * @param work The work queue, for adding new fixup work
  * @return True if the Promise was successfully resolved; false otherwise
  */
-bool ModelExecution::resolve_promise(ModelAction *write, Promise *promise)
+bool ModelExecution::resolve_promise(ModelAction *write, Promise *promise,
+		work_queue_t *work)
 {
 	ModelVector<ModelAction *> actions_to_check;
 
 	for (unsigned int i = 0; i < promise->get_num_readers(); i++) {
 		ModelAction *read = promise->get_reader(i);
-		read_from(read, write);
+		if (read_from(read, write)) {
+			/* Propagate the changed clock vector */
+			propagate_clockvector(read, work);
+		}
 		actions_to_check.push_back(read);
 	}
 	/* Make sure the promise's value matches the write's value */
diff --git a/execution.h b/execution.h
index bb4ebb0..ab4df36 100644
--- a/execution.h
+++ b/execution.h
@@ -141,7 +141,7 @@ private:
 	ModelAction * check_current_action(ModelAction *curr);
 	bool initialize_curr_action(ModelAction **curr);
 	bool process_read(ModelAction *curr);
-	bool process_write(ModelAction *curr);
+	bool process_write(ModelAction *curr, work_queue_t *work);
 	bool process_fence(ModelAction *curr);
 	bool process_mutex(ModelAction *curr);
 	bool process_thread_action(ModelAction *curr);
@@ -160,7 +160,8 @@ private:
 	void set_backtracking(ModelAction *act);
 	bool set_latest_backtrack(ModelAction *act);
 	Promise * pop_promise_to_resolve(const ModelAction *curr);
-	bool resolve_promise(ModelAction *curr, Promise *promise);
+	bool resolve_promise(ModelAction *curr, Promise *promise,
+			work_queue_t *work);
 	void compute_promises(ModelAction *curr);
 	void compute_relseq_breakwrites(ModelAction *curr);