OpBuilder builder(module);
  std::sort(tac_filters_->mutable_tac_filters()->pointer_begin(),
            tac_filters_->mutable_tac_filters()->pointer_end(),
            [](const TacFilter* a, const TacFilter* b) {
              const bool a_is_function_filter = a->has_function_filter();
              const bool b_is_function_filter = b->has_function_filter();
              if (a_is_function_filter != b_is_function_filter) {

message TacFilters {
  // A list of filters/rules to specify the parts that user wants to run on
  // other hardware.
  repeated TacFilter tac_filters = 1;
}

// A filter can be used for an op or function.
message TacFilter {
  oneof filter {
    OpFilter op_filter = 1;
    FunctionFilter function_filter = 2;
  }
}