// Copyright (c) 2024 PaddlePaddle Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#pragma once
#include "paddle/phi/common/memory_utils.h"
#include "paddle/phi/core/kernel_registry.h"

namespace phi {

template <typename T, typename Context>
void StraightThroughEstimatorGradKernel(const Context& dev_ctx,
                                        const DenseTensor& out_grad,
                                        DenseTensor* x_grad) {
  auto* d_out = &out_grad;
  auto* d_x = x_grad;
  PADDLE_ENFORCE_NOT_NULL(d_x,
                          common::errors::PreconditionNotMet(
                              "StraightThroughEstimatorGradKernel "
                              "doesn't have the output named x_grad."));

  // Initialize dx as same as d_out
  dev_ctx.template Alloc<T>(d_x);
  phi::Copy(dev_ctx, *d_out, dev_ctx.GetPlace(), false, d_x);
}

}  // namespace phi
