Status HandleGeneric(Node* n, std::vector<bool>* should_revisit);
  Status HandleNode(Node* n, std::vector<bool>* should_revisit,
                    bool use_optimistic_mode = false);

  Status GetFrameBasedTopologicalOrder(std::vector<Node*>* order);

  bool IsRootEnter(const Node* n) const {
    return IsEnter(n) && control_flow_info_[n->id()].parent_frame->IsSource();
  }

  bool IsRootExit(const Node* n) const {