X-Git-Url: http://plrg.eecs.uci.edu/git/?p=c11tester.git;a=blobdiff_plain;f=cyclegraph.cc;h=2c3a5936a89d8ac7dbb7e5b43e32b7a1cfd5ec6a;hp=168ad90cdb0c4930d045d2dd97d2d45cc2e2f068;hb=482c7447dd2f63823eb969c37dd6fb4e22991fde;hpb=86c1040ac133d94bcafac7e72b7a8353d2b5757d diff --git a/cyclegraph.cc b/cyclegraph.cc index 168ad90c..2c3a5936 100644 --- a/cyclegraph.cc +++ b/cyclegraph.cc @@ -6,11 +6,9 @@ /** Initializes a CycleGraph object. */ CycleGraph::CycleGraph() : - discovered(new HashTable(16)), + discovered(new HashTable(16)), hasCycles(false), - oldCycles(false), - hasRMWViolation(false), - oldRMWViolation(false) + oldCycles(false) { } @@ -20,31 +18,83 @@ CycleGraph::~CycleGraph() delete discovered; } +/** + * Add a CycleNode to the graph, corresponding to a store ModelAction + * @param act The write action that should be added + * @param node The CycleNode that corresponds to the store + */ +void CycleGraph::putNode(const ModelAction *act, CycleNode *node) +{ + actionToNode.put(act, node); +#if SUPPORT_MOD_ORDER_DUMP + nodeList.push_back(node); +#endif +} + +/** @return The corresponding CycleNode, if exists; otherwise NULL */ +CycleNode * CycleGraph::getNode_noCreate(const ModelAction *act) const +{ + return actionToNode.get(act); +} + +/** @return The corresponding CycleNode, if exists; otherwise NULL */ +CycleNode * CycleGraph::getNode_noCreate(const Promise *promise) const +{ + return readerToPromiseNode.get(promise->get_action()); +} + /** * @brief Returns the CycleNode corresponding to a given ModelAction + * + * Gets (or creates, if none exist) a CycleNode corresponding to a ModelAction + * * @param action The ModelAction to find a node for * @return The CycleNode paired with this action */ CycleNode * CycleGraph::getNode(const ModelAction *action) { - CycleNode *node = actionToNode.get(action); + CycleNode *node = getNode_noCreate(action); if (node == NULL) { node = new CycleNode(action); - actionToNode.put(action, node); -#if SUPPORT_MOD_ORDER_DUMP - nodeList.push_back(node); -#endif + putNode(action, node); } return node; } /** - * 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 = getNode_noCreate(promise); + 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 +void CycleGraph::addEdge(const T from, const U to) { ASSERT(from); ASSERT(to); @@ -52,44 +102,130 @@ void CycleGraph::addEdge(const ModelAction *from, const ModelAction *to) CycleNode *fromnode = getNode(from); CycleNode *tonode = getNode(to); - if (!hasCycles) { - // Reflexive edges are cycles - hasCycles = (from == to); + addNodeEdge(fromnode, tonode); +} + +/** + * @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; } - if (!hasCycles) { - // Check for Cycles - hasCycles = checkReachable(tonode, fromnode); + + /* 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); + } } - if (fromnode->addEdge(tonode)) - rollbackvector.push_back(fromnode); + /* 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; - CycleNode *rmwnode = fromnode->getRMW(); + 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 - * - * 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) { @@ -100,11 +236,10 @@ 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: @@ -121,18 +256,7 @@ void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw) } } - - 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 @@ -166,12 +290,13 @@ void CycleGraph::dumpGraphToFile(const char *filename) const #endif /** - * Checks whether one ModelAction can reach another. + * Checks whether one ModelAction can reach another ModelAction/Promise * @param from The ModelAction from which to begin exploration - * @param to The ModelAction to reach + * @param to The ModelAction or Promise to reach * @return True, @a from can reach @a to; otherwise, false */ -bool CycleGraph::checkReachable(const ModelAction *from, const ModelAction *to) const +template +bool CycleGraph::checkReachable(const ModelAction *from, const T *to) const { CycleNode *fromnode = actionToNode.get(from); CycleNode *tonode = actionToNode.get(to); @@ -188,15 +313,15 @@ bool CycleGraph::checkReachable(const ModelAction *from, const ModelAction *to) * @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 > queue; + std::vector< const CycleNode *, ModelAlloc > 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; @@ -224,7 +349,7 @@ bool CycleGraph::checkPromise(const ModelAction *fromact, Promise *promise) cons 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; } @@ -241,36 +366,31 @@ bool CycleGraph::checkPromise(const ModelAction *fromact, Promise *promise) cons 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. */ @@ -279,17 +399,24 @@ bool CycleGraph::checkForCycles() const 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) { } @@ -309,9 +436,68 @@ unsigned int CycleNode::getNumEdges() const 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 +static bool vector_remove_node(std::vector >& 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) { @@ -319,6 +505,7 @@ bool CycleNode::addEdge(CycleNode *node) if (edges[i] == node) return false; edges.push_back(node); + node->back_edges.push_back(this); return true; } @@ -341,3 +528,19 @@ bool CycleNode::setRMW(CycleNode *node) hasRMW = node; return false; } + +/** + * Convert a Promise CycleNode into a concrete-valued CycleNode. Should only be + * used when there's no existing ModelAction CycleNode for this write. + * + * @param writer The ModelAction which wrote the future value represented by + * this CycleNode + */ +void CycleNode::resolvePromise(const ModelAction *writer) +{ + ASSERT(is_promise()); + ASSERT(promise->is_compatible(writer)); + action = writer; + promise = NULL; + ASSERT(!is_promise()); +}