92 lines
3.2 KiB
C++
92 lines
3.2 KiB
C++
// Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "paddle/phi/kernels/log_softmax_grad_kernel.h"
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#include "paddle/phi/backends/cpu/cpu_context.h"
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#include "paddle/phi/core/kernel_registry.h"
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#include "paddle/phi/kernels/funcs/axis_utils.h"
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#include "paddle/phi/kernels/funcs/eigen/common.h"
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#include "paddle/phi/kernels/funcs/eigen/eigen_function.h"
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#include "paddle/phi/kernels/funcs/math_function.h"
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namespace phi {
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template <typename T, int MajorType = Eigen::RowMajor>
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using EigenMatrixTemplate = EigenMatrix<T, MajorType>;
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template <typename Context, typename T>
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struct LogSoftmaxGradFunctor {
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void operator()(const Context& dev_ctx,
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const DenseTensor* Y,
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const DenseTensor* dY,
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DenseTensor* dX,
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const int axis) {
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constexpr int kBatchDim = 0;
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constexpr int kClassDim = 1;
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const int n = funcs::SizeToAxis(axis, Y->dims());
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const int d = funcs::SizeFromAxis(axis, Y->dims());
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DDim dim_2d{n, d};
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auto y = EigenMatrixTemplate<T>::From(*Y, dim_2d);
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auto dy = EigenMatrixTemplate<T>::From(*dY, dim_2d);
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auto dx = EigenMatrixTemplate<T>::From(*dX, dim_2d);
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const int axis_dim = static_cast<int>(Y->dims()[axis]);
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const int batch_size = y.dimension(kBatchDim);
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const int num_classes = y.dimension(kClassDim);
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const int num_remain = num_classes / axis_dim;
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Eigen::DSizes<int, 1> along_class(kClassDim);
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Eigen::DSizes<int, 3> batch_axis_remain(batch_size, axis_dim, num_remain);
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Eigen::DSizes<int, 2> one_axis(1, axis_dim);
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dx.device(*dev_ctx.eigen_device()) =
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dy - (y.exp()) * (dy.reshape(batch_axis_remain)
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.sum(along_class)
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.broadcast(one_axis));
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}
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};
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template <typename T, typename Context>
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void LogSoftmaxGradKernel(const Context& dev_ctx,
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const DenseTensor& out,
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const DenseTensor& out_grad,
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int axis,
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DenseTensor* x_grad) {
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const int rank = out.dims().size();
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const int canonical_axis = funcs::CanonicalAxis(axis, rank);
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dev_ctx.template Alloc<T>(x_grad);
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// For 0D Tensor
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if (rank == 0) {
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funcs::set_constant(dev_ctx, x_grad, static_cast<T>(0.0));
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return;
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}
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if (out.numel() != 0) {
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LogSoftmaxGradFunctor<Context, T>()(
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dev_ctx, &out, &out_grad, x_grad, canonical_axis);
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}
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}
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} // namespace phi
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PD_REGISTER_KERNEL(log_softmax_grad,
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CPU,
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ALL_LAYOUT,
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phi::LogSoftmaxGradKernel,
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float,
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double) {}
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