LogicalResult FreezeVariables(ModuleOp module, tensorflow::Session* session) {
  if (failed(ValidateModule(module))) return failure();

  const tensorflow::DeviceMgr* mgr = nullptr;
  auto status = session->LocalDeviceManager(&mgr);
  if (!status.ok()) {
    module->emitError(
        absl::StrCat("failed to fetch device manager: ", status.message()));
    return failure();
  }