Function CreateMerge

tensorflow/cc/ops/while_loop.cc:66–88

Creates the `loop_var_idx`-th Merge node of a loop being constructed with `scope`. `enter_output` is the `loop_var_idx`-th Enter node's output.

// Creates the `loop_var_idx`-th Merge node of a loop being constructed with
// `scope`. `enter_output` is the `loop_var_idx`-th Enter node's output.
Status CreateMerge(const Scope& scope, int loop_var_idx,
                   const Output& enter_output, Output* merge_output) {
  // The merge nodes accept the while loop's back edges as an input (i.e. the
  // not-yet-created next iteration nodes). Use the underlying NodeBuilder API
  // directly to create the back edge.
  NodeBuilder::NodeOut enter_input(enter_output.node(), enter_output.index());

  const int next_output_index = 0;
  DataType dtype = enter_output.node()->output_type(0);
  NodeBuilder::NodeOut next_input(NextIterationName(scope, loop_var_idx),
                                  next_output_index, dtype);

  std::vector<NodeBuilder::NodeOut> input_list({enter_input, next_input});
  const string unique_name = scope.GetUniqueNameForOp("Merge");
  NodeBuilder builder = NodeBuilder(unique_name, "Merge").Input(input_list);
  scope.UpdateBuilder(&builder);

  Node* merge_node;
  TF_RETURN_IF_ERROR(builder.Finalize(scope.graph(), &merge_node));
  TF_RETURN_IF_ERROR(scope.DoShapeInference(merge_node));
  *merge_output = Output(merge_node, 0);
  return Status::OK();
}

// Creates the condition subgraph defined by `cond`.
Status CreateCond(const Scope& scope, const CondGraphBuilderFn& cond,