/** Initializes a CycleGraph object. */
CycleGraph::CycleGraph() :
- discovered(new HashTable<CycleNode *, CycleNode *, uintptr_t, 4, model_malloc, model_calloc, model_free>(16)),
+ discovered(new HashTable<const CycleNode *, const CycleNode *, uintptr_t, 4, model_malloc, model_calloc, model_free>(16)),
hasCycles(false),
- oldCycles(false),
- hasRMWViolation(false),
- oldRMWViolation(false)
+ oldCycles(false)
{
}
}
/**
- * Adds an edge between two ModelActions. The ModelAction @a to is ordered
- * after the ModelAction @a from.
- * @param to The edge points to this ModelAction
- * @param from The edge comes from this ModelAction
+ * @brief Returns a CycleNode corresponding to a promise
+ *
+ * Gets (or creates, if none exist) a CycleNode corresponding to a promised
+ * value.
+ *
+ * @param promise The Promise generated by a reader
+ * @return The CycleNode corresponding to the Promise
*/
-void CycleGraph::addEdge(const ModelAction *from, const ModelAction *to)
+CycleNode * CycleGraph::getNode(const Promise *promise)
+{
+ const ModelAction *reader = promise->get_action();
+ CycleNode *node = readerToPromiseNode.get(reader);
+ if (node == NULL) {
+ node = new CycleNode(promise);
+ readerToPromiseNode.put(reader, node);
+ }
+ return node;
+}
+
+/*
+ * @brief Adds an edge between objects
+ *
+ * This function will add an edge between any two objects which can be
+ * associated with a CycleNode. That is, if they have a CycleGraph::getNode
+ * implementation.
+ *
+ * The object to is ordered after the object from.
+ *
+ * @param to The edge points to this object, of type T
+ * @param from The edge comes from this object, of type U
+ */
+template <typename T, typename U>
+void CycleGraph::addEdge(const T from, const U to)
{
ASSERT(from);
ASSERT(to);
CycleNode *fromnode = getNode(from);
CycleNode *tonode = getNode(to);
- if (!hasCycles) {
- // Reflexive edges are cycles
- hasCycles = (from == to);
- }
- if (!hasCycles) {
- // Check for Cycles
+ addNodeEdge(fromnode, tonode);
+}
+
+/**
+ * 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);
-
- CycleNode *rmwnode = fromnode->getRMW();
-
/*
* If the fromnode has a rmwnode that is not the tonode, we should add
* an edge between its rmwnode and the tonode
- *
- * If tonode is also a rmw, don't do this check as the execution is
- * doomed and we'll catch the problem elsewhere, but we want to allow
- * for the possibility of sending to's write value to rmwnode
*/
- if (rmwnode != NULL && !to->is_rmw()) {
- if (!hasCycles) {
- // Check for Cycles
+ CycleNode *rmwnode = fromnode->getRMW();
+ if (rmwnode && rmwnode != tonode) {
+ if (!hasCycles)
hasCycles = checkReachable(tonode, rmwnode);
- }
if (rmwnode->addEdge(tonode))
rollbackvector.push_back(rmwnode);
}
}
-/** Handles special case of a RMW action. 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. Only one RMW
- * action can read from a given write.
+/**
+ * @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)
{
CycleNode *rmwnode = getNode(rmw);
/* Two RMW actions cannot read from the same write. */
- if (fromnode->setRMW(rmwnode)) {
- hasRMWViolation = true;
- } else {
+ 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:
}
}
-
- if (!hasCycles) {
- // Reflexive edges are cycles
- hasCycles = (from == rmw);
- }
- if (!hasCycles) {
- // With promises we could be setting up a cycle here if we aren't
- // careful...avoid it..
- hasCycles = checkReachable(rmwnode, fromnode);
- }
- if (fromnode->addEdge(rmwnode))
- rollbackvector.push_back(fromnode);
+ addNodeEdge(fromnode, rmwnode);
}
#if SUPPORT_MOD_ORDER_DUMP
* @param to The CycleNode to reach
* @return True, @a from can reach @a to; otherwise, false
*/
-bool CycleGraph::checkReachable(CycleNode *from, CycleNode *to) const
+bool CycleGraph::checkReachable(const CycleNode *from, const CycleNode *to) const
{
- std::vector< CycleNode *, ModelAlloc<CycleNode *> > queue;
+ std::vector< const CycleNode *, ModelAlloc<const CycleNode *> > queue;
discovered->reset();
queue.push_back(from);
discovered->put(from, from);
while (!queue.empty()) {
- CycleNode *node = queue.back();
+ const CycleNode *node = queue.back();
queue.pop_back();
if (node == to)
return true;
CycleNode *node = queue.back();
queue.pop_back();
- if (promise->increment_threads(node->getAction()->get_tid())) {
+ if (promise->eliminate_thread(node->getAction()->get_tid())) {
return true;
}
void CycleGraph::startChanges()
{
- ASSERT(rollbackvector.size() == 0);
- ASSERT(rmwrollbackvector.size() == 0);
+ ASSERT(rollbackvector.empty());
+ ASSERT(rmwrollbackvector.empty());
ASSERT(oldCycles == hasCycles);
- ASSERT(oldRMWViolation == hasRMWViolation);
}
/** Commit changes to the cyclegraph. */
void CycleGraph::commitChanges()
{
- rollbackvector.resize(0);
- rmwrollbackvector.resize(0);
+ rollbackvector.clear();
+ rmwrollbackvector.clear();
oldCycles = hasCycles;
- oldRMWViolation = hasRMWViolation;
}
/** Rollback changes to the previous commit. */
void CycleGraph::rollbackChanges()
{
- for (unsigned int i = 0; i < rollbackvector.size(); i++) {
+ for (unsigned int i = 0; i < rollbackvector.size(); i++)
rollbackvector[i]->popEdge();
- }
- for (unsigned int i = 0; i < rmwrollbackvector.size(); i++) {
+ for (unsigned int i = 0; i < rmwrollbackvector.size(); i++)
rmwrollbackvector[i]->clearRMW();
- }
hasCycles = oldCycles;
- hasRMWViolation = oldRMWViolation;
- rollbackvector.resize(0);
- rmwrollbackvector.resize(0);
+ rollbackvector.clear();
+ rmwrollbackvector.clear();
}
/** @returns whether a CycleGraph contains cycles. */
return hasCycles;
}
-bool CycleGraph::checkForRMWViolation() const
-{
- return hasRMWViolation;
-}
-
/**
* @brief Constructor for a CycleNode
* @param act The ModelAction for this node
*/
CycleNode::CycleNode(const ModelAction *act) :
action(act),
+ promise(NULL),
+ hasRMW(NULL)
+{
+}
+
+/**
+ * @brief Constructor for a Promise CycleNode
+ * @param promise The Promise which was generated
+ */
+CycleNode::CycleNode(const Promise *promise) :
+ action(NULL),
+ promise(promise),
hasRMW(NULL)
{
}
return edges.size();
}
+CycleNode * CycleNode::getBackEdge(unsigned int i) const
+{
+ return back_edges[i];
+}
+
+unsigned int CycleNode::getNumBackEdges() const
+{
+ return back_edges.size();
+}
+
+/**
+ * @brief Remove an element from a vector
+ * @param v The vector
+ * @param n The element to remove
+ * @return True if the element was found; false otherwise
+ */
+template <typename T>
+static bool vector_remove_node(std::vector<T, SnapshotAlloc<T> >& v, const T n)
+{
+ for (unsigned int i = 0; i < v.size(); i++) {
+ if (v[i] == n) {
+ v.erase(v.begin() + i);
+ return true;
+ }
+ }
+ return false;
+}
+
+/**
+ * @brief Remove a (forward) edge from this CycleNode
+ * @return The CycleNode which was popped, if one exists; otherwise NULL
+ */
+CycleNode * CycleNode::removeEdge()
+{
+ if (edges.empty())
+ return NULL;
+
+ CycleNode *ret = edges.back();
+ edges.pop_back();
+ vector_remove_node(ret->back_edges, this);
+ return ret;
+}
+
+/**
+ * @brief Remove a (back) edge from this CycleNode
+ * @return The CycleNode which was popped, if one exists; otherwise NULL
+ */
+CycleNode * CycleNode::removeBackEdge()
+{
+ if (back_edges.empty())
+ return NULL;
+
+ CycleNode *ret = back_edges.back();
+ back_edges.pop_back();
+ vector_remove_node(ret->edges, this);
+ return ret;
+}
+
/**
* Adds an edge from this CycleNode to another CycleNode.
* @param node The node to which we add a directed edge
+ * @return True if this edge is a new edge; false otherwise
*/
bool CycleNode::addEdge(CycleNode *node)
{
if (edges[i] == node)
return false;
edges.push_back(node);
+ node->back_edges.push_back(this);
return true;
}
projects / model-checker.git / blobdiff