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2026-07-13 12:40:42 +08:00

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// Copyright (c) 2023 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/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 IgammaGradFunctor {
IgammaGradFunctor(
const T* dout, const T* x, const T* a, T* output, int64_t numel)
: dout_(dout), x_(x), a_(a), output_(output), numel_(numel) {}
HOSTDEVICE void operator()(int64_t idx) const {
using MT = typename MPTypeTrait<T>::Type;
const MT mp_dout = static_cast<MT>(dout_[idx]);
const MT mp_x = static_cast<MT>(x_[idx]);
const MT mp_a = static_cast<MT>(a_[idx]);
const MT mp_a_1 = static_cast<MT>(a_[idx] - 1);
output_[idx] = static_cast<T>(mp_dout * -std::exp(-mp_x) *
std::pow(mp_x, mp_a_1) / std::tgamma(mp_a));
}
private:
const T* dout_;
const T* x_;
const T* a_;
T* output_;
int64_t numel_;
};
template <typename T, typename Context>
void GammainccGradKernel(const Context& dev_ctx,
const DenseTensor& x,
const DenseTensor& y,
const DenseTensor& d_out,
DenseTensor* d_y) {
if (d_y && d_y->numel() == 0) {
dev_ctx.template Alloc<T>(d_y);
return;
}
auto numel = d_out.numel();
auto* dout_data = d_out.data<T>();
auto* x_data = x.data<T>();
auto* y_data = y.data<T>();
auto* dy_data =
dev_ctx.template Alloc<T>(d_y, static_cast<size_t>(numel * sizeof(T)));
funcs::ForRange<Context> for_range(dev_ctx, numel);
IgammaGradFunctor<T> functor(dout_data, y_data, x_data, dy_data, numel);
for_range(functor);
}
} // namespace phi