From: Brian Norris <banorris@uci.edu>
Date: Sat, 2 Mar 2013 23:13:42 +0000 (-0800)
Subject: action: add get_return_value()
X-Git-Url: http://plrg.eecs.uci.edu/git/?p=cdsspec-compiler.git;a=commitdiff_plain;h=c1db87fb3d52c93feb22496fe1e8513e35320c3d

action: add get_return_value()

This return value is useful for both printing (debugging) and the
model-checker process_read() function.
---

diff --git a/action.cc b/action.cc
index 893c812..1007e76 100644
--- a/action.cc
+++ b/action.cc
@@ -416,6 +416,26 @@ uint64_t ModelAction::get_write_value() const
 	return value;
 }
 
+/**
+ * @brief Get the value returned by this action
+ *
+ * For atomic reads (including RMW), an operation returns the value it read.
+ * For atomic writes, an operation returns the value it wrote. For other
+ * operations, the return value varies (sometimes is a "don't care"), but the
+ * value is simply stored in the "value" field.
+ *
+ * @return This action's return value
+ */
+uint64_t ModelAction::get_return_value() const
+{
+	if (is_read())
+		return get_reads_from_value();
+	else if (is_write())
+		return get_write_value();
+	else
+		return value;
+}
+
 /** @return The Node associated with this ModelAction */
 Node * ModelAction::get_node() const
 {
@@ -548,14 +568,6 @@ void ModelAction::print() const
 		type_str = "unknown type";
 	}
 
-	uint64_t valuetoprint;
-	if (is_read())
-		valuetoprint = get_reads_from_value();
-	else if (is_write())
-		valuetoprint = get_write_value();
-	else
-		valuetoprint = value;
-
 	switch (this->order) {
 	case std::memory_order_relaxed:
 		mo_str = "relaxed";
@@ -578,7 +590,7 @@ void ModelAction::print() const
 	}
 
 	model_print("(%4d) Thread: %-2d   Action: %-13s   MO: %7s  Loc: %14p   Value: %-#18" PRIx64,
-			seq_number, id_to_int(tid), type_str, mo_str, location, valuetoprint);
+			seq_number, id_to_int(tid), type_str, mo_str, location, get_return_value());
 	if (is_read()) {
 		if (reads_from)
 			model_print("  Rf: %-3d", reads_from->get_seq_number());
diff --git a/action.h b/action.h
index 7c9146f..1b03bc4 100644
--- a/action.h
+++ b/action.h
@@ -82,6 +82,7 @@ public:
 	uint64_t get_value() const { return value; }
 	uint64_t get_reads_from_value() const;
 	uint64_t get_write_value() const;
+	uint64_t get_return_value() const;
 	const ModelAction * get_reads_from() const { return reads_from; }
 	Promise * get_reads_from_promise() const { return reads_from_promise; }
 
diff --git a/model.cc b/model.cc
index 4fca7aa..86289a0 100644
--- a/model.cc
+++ b/model.cc
@@ -853,7 +853,6 @@ ModelAction * ModelChecker::get_next_backtrack()
 bool ModelChecker::process_read(ModelAction *curr)
 {
 	Node *node = curr->get_node();
-	uint64_t value = VALUE_NONE;
 	while (true) {
 		bool updated = false;
 		switch (node->get_read_from_status()) {
@@ -874,7 +873,6 @@ bool ModelChecker::process_read(ModelAction *curr)
 			}
 
 			updated = r_modification_order(curr, rf);
-			value = rf->get_write_value();
 			read_from(curr, rf);
 			mo_graph->commitChanges();
 			mo_check_promises(curr, true);
@@ -884,7 +882,6 @@ bool ModelChecker::process_read(ModelAction *curr)
 			Promise *promise = curr->get_node()->get_read_from_promise();
 			if (promise->add_reader(curr))
 				priv->failed_promise = true;
-			value = promise->get_value();
 			curr->set_read_from_promise(promise);
 			mo_graph->startChanges();
 			if (!check_recency(curr, promise))
@@ -897,7 +894,6 @@ bool ModelChecker::process_read(ModelAction *curr)
 			/* Read from future value */
 			struct future_value fv = node->get_future_value();
 			Promise *promise = new Promise(curr, fv);
-			value = fv.value;
 			curr->set_read_from_promise(promise);
 			promises->push_back(promise);
 			mo_graph->startChanges();
@@ -908,7 +904,7 @@ bool ModelChecker::process_read(ModelAction *curr)
 		default:
 			ASSERT(false);
 		}
-		get_thread(curr)->set_return_value(value);
+		get_thread(curr)->set_return_value(curr->get_return_value());
 		return updated;
 	}
 }