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 893c812a1f39bd33f60a3b97291ffe9a525ae124..1007e762ee5258305bbd8ef5b403db5a874f17cc 100644 (file)
--- 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 7c9146fdda694adfd97c7f932f75822e53a4303c..1b03bc48943f5b24183c61cd372346a8f8a9b752 100644 (file)
--- 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 4fca7aadc48cd09b5c9a2d3490e54872796d0daf..86289a0738a7965727fb4620a0021bbb8e2c90d0 100644 (file)
--- 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;
        }
 }