}
};

// Register Op capabilities for specific hardware.
template <typename Hardware, typename Op>
struct TargetHardwareOpRegistration {
  explicit TargetHardwareOpRegistration(
      std::function<std::unique_ptr<TargetHardwareOperation>()>
          target_hardware_op_factory) {
    // TODO(b/177376459): remove this.

};
std::unique_ptr<TargetHardwareOperation> CreateConcatOp() {
  return std::make_unique<NNAPIConcatOp>();
}

#define TAC_REGISTER_NNAPI_OP(Op, Create)                                      \
  TargetHardwareOpRegistration<NNAPIHardware, Op> Op##_NNAPIHardware_hardware( \
      Create);

// Op registeration
TAC_REGISTER_NNAPI_OP(SquaredDifferenceOp, CreateBasicOpNoCost);
TAC_REGISTER_NNAPI_OP(ConcatenationOp, CreateConcatOp);

TargetHardwareRegistration<CpuHardware> cpu_hardware("Target device for CPU",
                                                     CreateCpuHardware);

#define TAC_REGISTER_CPU_OP(Op, Create)                                    \
  TargetHardwareOpRegistration<CpuHardware, Op> Op##_CpuHardware_hardware( \
      Create);

// Operation costs on CPU

// Currently used for these ops:
// tfl.conv_2d / tfl.depthwise_conv_2d / tfl.fully_connected

TargetHardwareRegistration<GpuHardware> gpu_hardware("Target device for GPU",
                                                     CreateGpuHardware);

#define TAC_REGISTER_GPU_OP(Op, Create)                                    \
  TargetHardwareOpRegistration<GpuHardware, Op> Op##_GpuHardware_hardware( \
      Create);

// Currently used for these ops:
// tfl.Abs / tfl.Average_pool_2d / tfl.Cos / tfl.div / tfl.exp / tfl.hardswish /