// the merged execute.
  auto old_region_results = parallel_execute.GetRegionOutputs(region_index);
  for (int i = 0, end = var_access_info.old_to_new_output_mapping.size();
       i < end; ++i) {
    if (var_access_info.old_to_new_output_mapping[i] < 0) continue;
    old_region_results[i].replaceAllUsesWith(new_parallel_execute_op->getResult(