if (IsNextIteration(curr_node) && IsMerge(out)) {
        // Edge NextIteration->Merge has been counted.
        continue;
      }
      ++num_ready_inputs[out->id()];
      if (!out->IsOp()) continue;  // Skip Sink/Source nodes.
      if (num_ready_inputs[out->id()] != out->in_edges().size()) continue;

      absl::string_view frame_name = control_flow_info_[out_id].frame_name;
      if (IsRootEnter(out)) {