return op->emitOpError(llvm::formatv(
          "bad '{0}' attribute at index {1}, not a string", kDevicesAttr, idx));

    if (DeviceNameUtils::ParseFullName(string_attr.getValue().str(), &device)) {
      devices->AddDevice(device);
    } else {
      return op->emitOpError(
          llvm::formatv("bad '{0}' attribute, '{1}', not a valid device",
                        kDevicesAttr, string_attr.getValue()));
    }
  }

  devices.push_back(FakeDevice::Make(gpu0, "compute capability: 7.0"));
  devices.push_back(FakeDevice::Make(gpu1));

  DeviceSet device_set;
  for (auto& device : devices) device_set.AddDevice(device.get());
  AddDevicesToOp(*module_ref, &device_set);

  auto devices_attr =
      (*module_ref)->getAttrOfType<mlir::DictionaryAttr>("tf.devices");
  ASSERT_NE(devices_attr, nullptr);