mo_graph->startChanges();
ASSERT(!is_infeasible());
- if (!check_recency(curr, rf))
- priv->too_many_reads = true;
- updated = r_modification_order(curr, rf);
-
- if (is_infeasible() && node->increment_read_from()) {
- mo_graph->rollbackChanges();
- priv->too_many_reads = false;
- continue;
+ if (!check_recency(curr, rf)) {
+ if (node->increment_read_from()) {
+ mo_graph->rollbackChanges();
+ continue;
+ } else {
+ priv->too_many_reads = true;
+ }
}
+ updated = r_modification_order(curr, rf);
value = rf->get_value();
read_from(curr, rf);
mo_graph->commitChanges();
mo_check_promises(curr, true);
-
break;
}
case READ_FROM_PROMISE: {
value = promise->get_value();
curr->set_read_from_promise(promise);
mo_graph->startChanges();
+ if (!check_recency(curr, promise))
+ priv->too_many_reads = true;
updated = r_modification_order(curr, promise);
mo_graph->commitChanges();
break;
return lastread;
}
-template <typename T>
-bool ModelChecker::should_read_instead(const ModelAction *curr, const ModelAction *rf, const T *other_rf) const
+/**
+ * A helper function for ModelChecker::check_recency, to check if the current
+ * thread is able to read from a different write/promise for 'params.maxreads'
+ * number of steps and if that write/promise should become visible (i.e., is
+ * ordered later in the modification order). This helps model memory liveness.
+ *
+ * @param curr The current action. Must be a read.
+ * @param rf The write/promise from which we plan to read
+ * @param other_rf The write/promise from which we may read
+ * @return True if we were able to read from other_rf for params.maxreads steps
+ */
+template <typename T, typename U>
+bool ModelChecker::should_read_instead(const ModelAction *curr, const T *rf, const U *other_rf) const
{
/* Need a different write/promise */
if (other_rf->equals(rf))
}
/**
- * Checks whether a thread has read from the same write for too many times
- * without seeing the effects of a later write.
+ * Checks whether a thread has read from the same write or Promise for too many
+ * times without seeing the effects of a later write/Promise.
*
* Basic idea:
- * 1) there must a different write that we could read from that would satisfy the modification order,
- * 2) we must have read from the same value in excess of maxreads times, and
- * 3) that other write must have been in the reads_from set for maxreads times.
+ * 1) there must a different write/promise that we could read from,
+ * 2) we must have read from the same write/promise in excess of maxreads times,
+ * 3) that other write/promise must have been in the reads_from set for maxreads times, and
+ * 4) that other write/promise must be mod-ordered after the write/promise we are reading.
*
* If so, we decide that the execution is no longer feasible.
*
* @param curr The current action. Must be a read.
- * @param rf The store from which we might read.
+ * @param rf The ModelAction/Promise from which we might read.
* @return True if the read should succeed; false otherwise
*/
-bool ModelChecker::check_recency(ModelAction *curr, const ModelAction *rf) const
+template <typename T>
+bool ModelChecker::check_recency(ModelAction *curr, const T *rf) const
{
if (!params.maxreads)
return true;