+/**
+ * @return false if the resolution results in a cycle; true otherwise
+ */
+bool CycleGraph::resolvePromise(ModelAction *reader, ModelAction *writer,
+ promise_list_t *mustResolve)
+{
+ CycleNode *promise_node = readerToPromiseNode.get(reader);
+ CycleNode *w_node = actionToNode.get(writer);
+ ASSERT(promise_node);
+
+ if (w_node)
+ return mergeNodes(w_node, promise_node, mustResolve);
+ /* No existing write-node; just convert the promise-node */
+ promise_node->resolvePromise(writer);
+ readerToPromiseNode.put(reader, NULL); /* erase promise_node */
+ putNode(writer, promise_node);
+ return true;
+}
+
+/**
+ * @brief Merge two CycleNodes that represent the same write
+ *
+ * Note that this operation cannot be rolled back.
+ *
+ * @param w_node The write ModelAction node with which to merge
+ * @param p_node The Promise node to merge. Will be destroyed after this
+ * function.
+ * @param mustMerge Return (pass-by-reference) any additional Promises that
+ * must also be merged with w_node
+ *
+ * @return false if the merge results in a cycle; true otherwise
+ */
+bool CycleGraph::mergeNodes(CycleNode *w_node, CycleNode *p_node,
+ promise_list_t *mustMerge)
+{
+ ASSERT(!w_node->is_promise());
+ ASSERT(p_node->is_promise());
+ const Promise *promise = p_node->getPromise();
+ if (!promise->is_compatible(w_node->getAction())) {
+ hasCycles = true;
+ return false;
+ }
+
+ /* Transfer back edges to w_node */
+ while (p_node->getNumBackEdges() > 0) {
+ CycleNode *back = p_node->removeBackEdge();
+ if (back != w_node) {
+ if (back->is_promise()) {
+ if (checkReachable(w_node, back)) {
+ /* Edge would create cycle; merge instead */
+ mustMerge->push_back(back->getPromise());
+ if (!mergeNodes(w_node, back, mustMerge))
+ return false;
+ } else
+ back->addEdge(w_node);
+ } else
+ addNodeEdge(back, w_node);
+ }
+ }
+
+ /* Transfer forward edges to w_node */
+ while (p_node->getNumEdges() > 0) {
+ CycleNode *forward = p_node->removeEdge();
+ if (forward != w_node) {
+ if (forward->is_promise()) {
+ if (checkReachable(forward, w_node)) {
+ mustMerge->push_back(forward->getPromise());
+ if (!mergeNodes(w_node, forward, mustMerge))
+ return false;
+ } else
+ w_node->addEdge(forward);
+ } else
+ addNodeEdge(w_node, forward);
+ }
+ }
+
+ /* erase p_node */
+ readerToPromiseNode.put(promise->get_action(), NULL);
+ delete p_node;
+
+ return !hasCycles;
+}
+
+/**
+ * Adds an edge between two CycleNodes.
+ * @param fromnode The edge comes from this CycleNode
+ * @param tonode The edge points to this CycleNode
+ */
+void CycleGraph::addNodeEdge(CycleNode *fromnode, CycleNode *tonode)
+{
+ if (!hasCycles)
+ hasCycles = checkReachable(tonode, fromnode);
+
+ if (fromnode->addEdge(tonode))
+ rollbackvector.push_back(fromnode);
+
+ /*
+ * If the fromnode has a rmwnode that is not the tonode, we should add
+ * an edge between its rmwnode and the tonode
+ */
+ CycleNode *rmwnode = fromnode->getRMW();
+ if (rmwnode && rmwnode != tonode) {
+ if (!hasCycles)
+ hasCycles = checkReachable(tonode, rmwnode);
+
+ if (rmwnode->addEdge(tonode))
+ rollbackvector.push_back(rmwnode);
+ }
+}
+
+/**
+ * @brief Add an edge between a write and the RMW which reads from it
+ *
+ * Handles special case of a RMW action, where the ModelAction rmw reads from
+ * the ModelAction from. The key differences are:
+ * (1) no write can occur in between the rmw and the from action.
+ * (2) Only one RMW action can read from a given write.
+ *
+ * @param from The edge comes from this ModelAction
+ * @param rmw The edge points to this ModelAction; this action must read from
+ * ModelAction from
+ */
+void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw)
+{
+ ASSERT(from);
+ ASSERT(rmw);
+
+ CycleNode *fromnode = getNode(from);
+ CycleNode *rmwnode = getNode(rmw);
+
+ /* Two RMW actions cannot read from the same write. */
+ if (fromnode->setRMW(rmwnode))
+ hasCycles = true;
+ else
+ rmwrollbackvector.push_back(fromnode);
+
+ /* Transfer all outgoing edges from the from node to the rmw node */
+ /* This process should not add a cycle because either:
+ * (1) The rmw should not have any incoming edges yet if it is the
+ * new node or
+ * (2) the fromnode is the new node and therefore it should not
+ * have any outgoing edges.
+ */
+ for (unsigned int i = 0; i < fromnode->getNumEdges(); i++) {
+ CycleNode *tonode = fromnode->getEdge(i);
+ if (tonode != rmwnode) {
+ if (rmwnode->addEdge(tonode))
+ rollbackvector.push_back(rmwnode);
+ }
+ }
+
+ addNodeEdge(fromnode, rmwnode);
+}
+
+#if SUPPORT_MOD_ORDER_DUMP
+void CycleGraph::dumpNodes(FILE *file) const
+{
+ for (unsigned int i = 0; i < nodeList.size(); i++) {
+ CycleNode *cn = nodeList[i];
+ const ModelAction *action = cn->getAction();
+ fprintf(file, "N%u [label=\"%u, T%u\"];\n", action->get_seq_number(), action->get_seq_number(), action->get_tid());
+ if (cn->getRMW() != NULL) {
+ fprintf(file, "N%u -> N%u[style=dotted];\n", action->get_seq_number(), cn->getRMW()->getAction()->get_seq_number());
+ }
+ for (unsigned int j = 0; j < cn->getNumEdges(); j++) {
+ CycleNode *dst = cn->getEdge(j);
+ const ModelAction *dstaction = dst->getAction();
+ fprintf(file, "N%u -> N%u;\n", action->get_seq_number(), dstaction->get_seq_number());
+ }
+ }
+}
+
+void CycleGraph::dumpGraphToFile(const char *filename) const
+{
+ char buffer[200];
+ sprintf(buffer, "%s.dot", filename);
+ FILE *file = fopen(buffer, "w");
+ fprintf(file, "digraph %s {\n", filename);
+ dumpNodes(file);
+ fprintf(file, "}\n");
+ fclose(file);
+}
+#endif
+
+/**
+ * Checks whether one ModelAction can reach another ModelAction/Promise
+ * @param from The ModelAction from which to begin exploration
+ * @param to The ModelAction or Promise to reach
+ * @return True, @a from can reach @a to; otherwise, false
+ */
+template <typename T>
+bool CycleGraph::checkReachable(const ModelAction *from, const T *to) const
+{
+ CycleNode *fromnode = actionToNode.get(from);
+ CycleNode *tonode = actionToNode.get(to);
+
+ if (!fromnode || !tonode)
+ return false;
+
+ return checkReachable(fromnode, tonode);
+}
+
+/**
+ * Checks whether one CycleNode can reach another.
+ * @param from The CycleNode from which to begin exploration
+ * @param to The CycleNode to reach
+ * @return True, @a from can reach @a to; otherwise, false
+ */
+bool CycleGraph::checkReachable(const CycleNode *from, const CycleNode *to) const
+{
+ std::vector< const CycleNode *, ModelAlloc<const CycleNode *> > queue;
+ discovered->reset();