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

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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 <type_traits>
#include <vector>
#include "paddle/phi/common/amp_type_traits.h"
#include "paddle/phi/kernels/funcs/eigen/common.h"
#include "paddle/phi/kernels/funcs/eigen/eigen_function.h"
#include "paddle/phi/kernels/funcs/reduce_grad_functions.h"
#include "paddle/phi/kernels/logsumexp_grad_kernel.h"
namespace phi {
template <typename T>
struct LogsumexpGradFunctor {
template <typename Context,
typename X,
typename Y,
typename DX,
typename DY,
typename Dim>
void operator()(const Context& place,
X* x,
Y* y,
DX* dx,
DY* dy,
const Dim& dim,
int size UNUSED) {
using MT = typename MPTypeTrait<T>::Type;
auto x_mt = (*x).template cast<MT>();
auto y_mt = (*y).template cast<MT>();
auto dy_mt = (*dy).template cast<MT>();
dx->device(place) =
(dy_mt.broadcast(dim) * (x_mt - y_mt.broadcast(dim)).exp())
.template cast<T>();
}
};
template <typename T, typename Context>
void LogsumexpGradKernel(const Context& dev_ctx,
const DenseTensor& in,
const DenseTensor& out,
const DenseTensor& out_grad,
const std::vector<int>& axis_in,
bool keepdim UNUSED,
bool reduce_all,
DenseTensor* in_grad) {
if (in_grad && in_grad->numel() == 0) {
dev_ctx.template Alloc<T>(in_grad);
return;
}
std::vector<int64_t> axis;
axis.reserve(axis_in.size());
std::for_each(axis_in.begin(), axis_in.end(), [&axis](const int& t) {
axis.push_back(static_cast<int64_t>(t));
});
dev_ctx.template Alloc<T>(in_grad);
reduce_all = recompute_reduce_all(in, axis, reduce_all);
if (reduce_all) {
auto x = EigenVector<T>::Flatten(in);
auto y = EigenVector<T>::Flatten(out);
auto dy = EigenVector<T>::Flatten(out_grad);
auto dx = EigenVector<T>::Flatten(*in_grad);
auto& place = *dev_ctx.eigen_device();
auto broadcast_dim = Eigen::array<int, 1>({{static_cast<int>(in.numel())}});
LogsumexpGradFunctor<T>()(
place, &x, &y, &dx, &dy, broadcast_dim, broadcast_dim[0]);
} else {
int rank = in.dims().size();
LogsumexpGradFunctor<T> functor;
std::vector<int32_t> axis32;
axis32.reserve(axis.size());
std::for_each(axis.begin(), axis.end(), [&axis32](const int64_t& t) {
axis32.push_back(t);
});
switch (rank) {
case 1:
funcs::ReduceGradFunctor<Context, T, 1, LogsumexpGradFunctor<T>>(
dev_ctx, in, out, out_grad, in_grad, functor, axis32);
break;
case 2:
funcs::ReduceGradFunctor<Context, T, 2, LogsumexpGradFunctor<T>>(
dev_ctx, in, out, out_grad, in_grad, functor, axis32);
break;
case 3:
funcs::ReduceGradFunctor<Context, T, 3, LogsumexpGradFunctor<T>>(
dev_ctx, in, out, out_grad, in_grad, functor, axis32);
break;
case 4:
funcs::ReduceGradFunctor<Context, T, 4, LogsumexpGradFunctor<T>>(
dev_ctx, in, out, out_grad, in_grad, functor, axis32);
break;
default:
PADDLE_THROW(common::errors::Unimplemented(
"Unsupported dimensions, please keep maximum dimensions of input "
"data less than 4."));
break;
}
}
}
} // namespace phi