Method CreateEnterNodes

tensorflow/core/common_runtime/lower_while_op.cc:201–238

}

Status LowerWhileHelper::CreateEnterNodes() {
  // Note: `Node::input_edge` runs in  O(num_inputs) so we use
  // `Node::input_edges` instead so that below loop runs in O(num_inputs) time
  // and not O(num_inputs^2).
  std::vector<const Edge*> edges;
  TF_RETURN_IF_ERROR(while_op_->input_edges(&edges));
  for (const Edge* edge : edges) {
    Node* enter_node;
    TF_RETURN_IF_ERROR(NodeBuilder(NewName("enter"), "Enter",
                                   graph_->op_registry(), &debug_info_)
                           .Input(NodeOut(edge->src(), edge->src_output()))
                           .Attr("frame_name", name_)
                           .Attr("parallel_iterations", parallel_iterations_)
                           .Device(while_op_->requested_device())
                           .Finalize(graph_, &enter_node));
    enter_nodes_[edge->dst_input()] = enter_node;
  }
  // Create a NoOp node that takes incoming control inputs of the original While
  // op as control inputs and use it as a control input for all Enter nodes.
  std::vector<Node*> control_inputs;
  for (const Edge* e : while_op_->in_edges()) {
    if (e->IsControlEdge()) {
      control_inputs.push_back(e->src());
    }
  }
  if (!control_inputs.empty()) {
    Node* incoming_control_node;
    TF_RETURN_IF_ERROR(NodeBuilder(NewName("LoopControlInputs"), "NoOp",
                                   graph_->op_registry(), &debug_info_)
                           .ControlInputs(control_inputs)
                           .Device(while_op_->requested_device())
                           .Finalize(graph_, &incoming_control_node));
    for (Node* n : enter_nodes_) {
      graph_->AddControlEdge(incoming_control_node, n);
    }
  }
  return Status::OK();
}

Status LowerWhileHelper::CreateMergeNodes() {
  for (Node* enter_node : enter_nodes_) {