Function AggregateForApply

tensorflow/core/graph/graph_constructor.cc:1663–1695

}

void AggregateForApply(Graph* dest, Node* n,
    map_node_list& duplicated_nodes, int grad_input) {
  const Edge* e = nullptr;
  TF_CHECK_OK(n->input_edge(grad_input, &e));
  auto grad = e->src();
  auto duplicate_grads = duplicated_nodes[grad];
  std::vector<NodeDefBuilder::NodeOut> src_list;
  src_list.emplace_back(grad->name(), e->src_output(),
      grad->output_type(0));
  for (auto it : duplicate_grads) {
    src_list.emplace_back(it->name(), e->src_output(),
        it->output_type(0));
  }

  NodeDef node_def;
  TF_CHECK_OK(NodeDefBuilder(n->name() + "/aggr_addn", "AddN")
      .Device(n->assigned_device_name())
      .Input(src_list)
      .Attr("T", grad->output_type(0))
      .Finalize(&node_def));

  Status s;
  Node* aggregate_node = dest->AddNode(node_def, &s);
  TF_CHECK_OK(s);
  aggregate_node->set_assigned_device_name(n->assigned_device_name());

  dest->RemoveEdge(e);
  dest->AddEdge(aggregate_node, 0, n, grad_input);
  dest->AddEdge(grad, 0, aggregate_node, 0);
  for (size_t i = 0; i < duplicate_grads.size(); ++i) {
    dest->AddEdge(duplicate_grads[i], 0, aggregate_node, i+1);
  }
}


void AggregateForSparseApply(Graph* dest, Node* n,