cyclegraph: add edgeCreatesCycle() function

[model-checker.git] / cyclegraph.cc

diff --git a/cyclegraph.cc b/cyclegraph.cc
index e3d0d8366694d53c44170ba589062df01d179aa0..ec0ce45f55ae65ae77325889b0aa0bfe84444cf8 100644 (file)
--- a/cyclegraph.cc
+++ b/cyclegraph.cc
@@ -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