cyclegraph: add edgeCreatesCycle() function

[c11tester.git] / cyclegraph.cc

diff --git a/cyclegraph.cc b/cyclegraph.cc
index 3949b6ec86d885056282a0b84d0975267da13cdd..ec0ce45f55ae65ae77325889b0aa0bfe84444cf8 100644 (file)
--- a/cyclegraph.cc
+++ b/cyclegraph.cc
@@ -6,7 +6,7 @@
 
 /** 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),
@@ -62,14 +62,8 @@ 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);
-       }
-       if (!hasCycles) {
-               // Check for Cycles
-               hasCycles = checkReachable(tonode, fromnode);
-       }
+       if (!hasCycles)
+               hasCycles = edgeCreatesCycle(fromnode, tonode);
 
        if (fromnode->addEdge(tonode))
                rollbackvector.push_back(fromnode);
@@ -86,10 +80,8 @@ void CycleGraph::addEdge(const ModelAction *from, const ModelAction *to)
         * for the possibility of sending to's write value to rmwnode
         */
        if (rmwnode != NULL && !to->is_rmw()) {
-               if (!hasCycles) {
-                       // Check for Cycles
-                       hasCycles = checkReachable(tonode, rmwnode);
-               }
+               if (!hasCycles)
+                       hasCycles = edgeCreatesCycle(rmwnode, tonode);
 
                if (rmwnode->addEdge(tonode))
                        rollbackvector.push_back(rmwnode);
@@ -131,16 +123,9 @@ void CycleGraph::addRMWEdge(const ModelAction *from, const ModelAction *rmw)
                }
        }
 
+       if (!hasCycles)
+               hasCycles = edgeCreatesCycle(fromnode, rmwnode);
 
-       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);
 }
@@ -175,6 +160,18 @@ void CycleGraph::dumpGraphToFile(const char *filename) const
 }
 #endif
 
+/**
+ * Checks whether the addition of an edge between these two nodes would create
+ * a cycle in the graph.
+ * @param from The CycleNode from which the edge would start
+ * @param to The CycleNode to which the edge would point
+ * @return True if this edge would create a cycle; false otherwise
+ */
+bool CycleGraph::edgeCreatesCycle(const CycleNode *from, const CycleNode *to) const
+{
+       return (from == to) || checkReachable(to, from);
+}
+
 /**
  * Checks whether one ModelAction can reach another.
  * @param from The ModelAction from which to begin exploration
@@ -198,15 +195,15 @@ 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<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;