message: removing extra bool array as it is not needed
diff: @@ -167,11 +167,12 @@ Status SymbolicGradientBuilder::BackpropAlongEdge(const Output& dst_grad,
  std::vector<bool> SymbolicGradientBuilder::GetReachableNodes() {
  std::vector<bool> reachable_nodes(scope_.graph()->num_node_ids(), false);
  std::deque<Node*> queue;
  - std::vector<bool> visited(scope_.graph()->num_node_ids(), false);
  for (const Output& out : outputs_) {
  - if (!reachable_nodes[out.node()->id()]) {
  - queue.push_back(out.node());
  - reachable_nodes[out.node()->id()] = true;
  + const Node* const out_node = out.node();
  + const int out_node_id = out_node->id();
  + if (!reachable_nodes[out_node_id]) {
  + queue.push_back(out_node);
  + reachable_nodes[out_node_id] = true;
  }
  }
  @@ -180,10 +181,12 @@ std::vector<bool> SymbolicGradientBuilder::GetReachableNodes() {
  queue.pop_front();
  for (const Edge* e : n->in_edges()) {
  if (e->IsControlEdge()) continue;
  - if (visited[e->src()->id()]) continue;
  - queue.push_back(e->src());
  - reachable_nodes[e->src()->id()] = true;
  - visited[e->src()->id()] = true;
  + const Node* const src_node = e->src();
  + const int src_node_id = src_node->id();
  + if (!reachable_nodes[src_node_id]) {
  + queue.push_back(src_node);
  + reachable_nodes[src_node_id] = true;
  + }
  }
  }
  return reachable_nodes;
  