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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.
#include "paddle/phi/kernels/dropout_grad_kernel.h"
#include "paddle/phi/backends/cpu/cpu_context.h"
#include "paddle/phi/core/kernel_registry.h"
#include "paddle/phi/kernels/funcs/eigen/common.h"
namespace phi {
template <typename T, typename Context>
void DropoutNdGradKernel(const Context& dev_ctx,
const DenseTensor& mask,
const DenseTensor& out_grad,
const Scalar& p,
bool is_test,
const std::string& mode,
const std::vector<int>& axis,
DenseTensor* x_grad) {
auto* grad_x = x_grad;
auto* grad_y = &out_grad;
dev_ctx.template Alloc<T>(grad_x);
auto dX = EigenVector<T>::Flatten(*grad_x);
auto dY = EigenVector<T>::Flatten(*grad_y);
float prob = p.to<float>();
auto& place = *dev_ctx.eigen_device();
auto& dropout_implementation = mode;
if (is_test == true) {
if (dropout_implementation == "upscale_in_train") {
dX.device(place) = static_cast<T>(1) * dY;
} else {
dX.device(place) = dY * static_cast<T>(1.0f - prob);
}
} else {
std::vector<int64_t> out_dims = vectorize(out_grad.dims());
auto M = EigenVector<uint8_t>::Flatten(mask);
if (dropout_implementation == "upscale_in_train") {
if (prob == 1.0f) {
dX.device(place) = static_cast<T>(0) * dY;
} else {
if (axis.empty()) {
dX.device(place) = dY * M.cast<T>() / static_cast<T>(1.0f - prob);
} else {
dX.device(place) = dY * M.broadcast(out_dims).cast<T>() /
static_cast<T>(1.0f - prob);
}
}
} else {
if (axis.empty()) {
dX.device(place) = dY * M.cast<T>();
} else {
dX.device(place) = dY * M.broadcast(out_dims).cast<T>();
}
}
}
}
template <typename T, typename Context>
void DropoutGradRawKernel(const Context& dev_ctx,
const DenseTensor& mask,
const DenseTensor& out_grad,
const Scalar& p,
bool is_test,
const std::string& mode,
DenseTensor* x_grad) {
DropoutNdGradKernel<T, Context>(
dev_ctx, mask, out_grad, p.to<float>(), is_test, mode, {}, x_grad);
}
} // namespace phi
PD_REGISTER_KERNEL(dropout_grad,
CPU,
ALL_LAYOUT,
phi::DropoutGradRawKernel,
float,
double,
phi::float16,
phi::bfloat16) {}
PD_REGISTER_KERNEL(
dropout_nd_grad, CPU, ALL_LAYOUT, phi::DropoutNdGradKernel, float, double) {
}