}
    buffer_data_map_.erase(it);
    it = buffer_data_map_.begin();
    buffer_data_exported_ = true;
  }
  // pad 16 bytes for the last buffer for XNNPack
  result.Append("\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
  // pad to be 16 bytes aligned
  {
    std::string pad(kFbAlignment - result.size() % kFbAlignment, '\0');
    result.Append(std::move(pad));
  }

  for (auto& it : custom_op_data_map_) {