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paddlepaddle--paddle/paddle/phi/kernels/impl/digamma_grad_kernel_impl.h
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// 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 <unsupported/Eigen/SpecialFunctions>
#include "paddle/phi/common/amp_type_traits.h"
#include "paddle/phi/core/dense_tensor.h"
#include "paddle/phi/kernels/funcs/for_range.h"
namespace phi {
template <typename T>
struct DigammaGradFunctor {
DigammaGradFunctor(const T* dout, const T* x, T* output, int64_t numel)
: dout_(dout), x_(x), output_(output), numel_(numel) {}
HOSTDEVICE void operator()(int64_t idx) const {
using MPType = typename MPTypeTrait<T>::Type;
const MPType mp_dout = static_cast<MPType>(dout_[idx]);
const MPType mp_x = static_cast<MPType>(x_[idx]);
output_[idx] =
static_cast<T>(mp_dout * Eigen::numext::polygamma(MPType(1), mp_x));
}
private:
const T* dout_;
const T* x_;
T* output_;
int64_t numel_;
};
template <typename T, typename Context>
void DigammaGradKernel(const Context& dev_ctx,
const DenseTensor& x,
const DenseTensor& out_grad,
DenseTensor* x_grad) {
dev_ctx.template Alloc<T>(x_grad);
if (x_grad && x_grad->numel() == 0) {
return;
}
auto* dout_data = out_grad.data<T>();
auto* x_data = x.data<T>();
auto* dx_data = x_grad->data<T>();
auto numel = out_grad.numel();
funcs::ForRange<Context> for_range(dev_ctx, numel);
DigammaGradFunctor<T> functor(dout_data, x_data, dx_data, numel);
for_range(functor);
}
} // namespace phi