// Copyright (c) 2022 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/fluid/prim/api/manual/prim_api/prim_api.h"
#include "paddle/fluid/prim/api/manual/utils/utils.h"
namespace paddle {
namespace prim {

// This function should have as same signature as phi, which defined in
// paddle/phi/api/backward/backward_api.h
template <typename T>
void tanh_grad(const Tensor& out, const Tensor& grad_out, Tensor* grad_x) {
  auto tmp = pow<T>(out, 2.0);
  tmp = scale<T>(tmp, -1.0, 1.0, true);
  auto grad_x_tmp = multiply<T>(grad_out, tmp);
  grad_x->set_impl(grad_x_tmp.impl());
}
}  // namespace prim
}  // namespace paddle