void ExplodedGraph::collectNode(ExplodedNode *node) {
  // Removing a node means:
  // (a) changing the predecessors successor to the successor of this node
  // (b) changing the successors predecessor to the predecessor of this node
  // (c) Putting 'node' onto freeNodes.
  assert(node->pred_size() == 1 || node->succ_size() == 1);
  ExplodedNode *pred = *(node->pred_begin());
  ExplodedNode *succ = *(node->succ_begin());
  pred->replaceSuccessor(succ);
  succ->replacePredecessor(pred);
  FreeNodes.push_back(node);
  Nodes.RemoveNode(node);
  --NumNodes;
  node->~ExplodedNode();  
}
void ExplodedGraph::reclaimRecentlyAllocatedNodes() {
  if (!recentlyAllocatedNodes)
    return;
  NodeList &nl = *getNodeList(recentlyAllocatedNodes);
 
  // Reclaimn all nodes that match *all* the following criteria:
  //
  // (1) 1 predecessor (that has one successor)
  // (2) 1 successor (that has one predecessor)
  // (3) The ProgramPoint is for a PostStmt.
  // (4) There is no 'tag' for the ProgramPoint.
  // (5) The 'store' is the same as the predecessor.
  // (6) The 'GDM' is the same as the predecessor.
  // (7) The LocationContext is the same as the predecessor.
  // (8) The PostStmt is for a non-CFGElement expression.
  
  for (NodeList::iterator i = nl.begin(), e = nl.end() ; i != e; ++i) {
    ExplodedNode *node = *i;
    
    // Conditions 1 and 2.
    if (node->pred_size() != 1 || node->succ_size() != 1)
      continue;

    ExplodedNode *pred = *(node->pred_begin());
    if (pred->succ_size() != 1)
      continue;

    ExplodedNode *succ = *(node->succ_begin());
    if (succ->pred_size() != 1)
      continue;

    // Condition 3.
    ProgramPoint progPoint = node->getLocation();
    if (!isa<PostStmt>(progPoint))
      continue;
    // Condition 4.
    PostStmt ps = cast<PostStmt>(progPoint);
    if (ps.getTag())
      continue;

    if (isa<BinaryOperator>(ps.getStmt()))
      continue;

    // Conditions 5, 6, and 7.
    const ProgramState *state = node->getState();
    const ProgramState *pred_state = pred->getState();    
    if (state->store != pred_state->store || state->GDM != pred_state->GDM ||
        progPoint.getLocationContext() != pred->getLocationContext())
      continue;

    // Condition 8.
    if (node->getCFG().isBlkExpr(ps.getStmt()))
      continue;
    
    // If we reach here, we can remove the node.  This means:
    // (a) changing the predecessors successor to the successor of this node
    // (b) changing the successors predecessor to the predecessor of this node
    // (c) Putting 'node' onto freeNodes.
    pred->replaceSuccessor(succ);
    succ->replacePredecessor(pred);
    if (!freeNodes)
      freeNodes = new NodeList();
    getNodeList(freeNodes)->push_back(node);
    Nodes.RemoveNode(node);
    --NumNodes;
    node->~ExplodedNode();
  }
  
  nl.clear();
}