#define DEFINE_CPU_ACTIVATION_KERNEL(name, functor_class)               \
  template <typename T, typename Context>                               \
  void name##Kernel(                                                    \
      const Context& dev_ctx, const DenseTensor& x, DenseTensor* out) { \
    funcs::functor_class<T> functor;                                    \
    if (out && out->numel() == 0) {                                     \
      dev_ctx.template Alloc<T>(out);                                   \
      return;                                                           \
    }                                                                   \
    ActivationImpl<T, T, Context, funcs::functor_class<T>>(             \
        dev_ctx, x, out, functor);                                      \
  }

    if (out && out->numel() == 0) {                                     \
      dev_ctx.template Alloc<T>(out);                                   \
      return;                                                           \
    }