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paddlepaddle--paddle/paddle/phi/kernels/impl/trace_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
#if defined(__NVCC__) || defined(__HIPCC__)
#include <thrust/device_vector.h>
#include <thrust/host_vector.h>
#endif
#include <algorithm>
#include "paddle/phi/kernels/funcs/for_range.h"
#include "paddle/phi/kernels/funcs/math_function.h"
namespace phi {
template <typename T>
struct TraceGradFunctor {
TraceGradFunctor(const T* d_out,
const int64_t* out_stride,
const int64_t* x_strides,
int64_t pos,
int64_t dim_size,
int64_t dim1,
int64_t dim2,
int64_t diag_size,
T* d_x)
: d_out_(d_out),
out_stride_(out_stride),
x_strides_(x_strides),
pos_(pos),
dim_size_(dim_size),
dim1_(dim1),
dim2_(dim2),
diag_size_(diag_size),
d_x_(d_x) {}
HOSTDEVICE void operator()(size_t idx) const {
int64_t num = idx - pos_;
int64_t position = 0;
if (num >= 0) {
int64_t dim1 = 0;
int64_t dim2 = 0;
int64_t out_idx = 0;
for (int64_t i = 0; i < dim_size_; i++) {
if (i != dim1_ && i != dim2_) {
position += num / x_strides_[i] * out_stride_[out_idx++];
} else if (i == dim1_) {
dim1 = num / x_strides_[i];
} else {
dim2 = num / x_strides_[i];
}
num = num % x_strides_[i];
}
if (dim1 == dim2 && dim1 < diag_size_) {
d_x_[idx] = d_out_[position];
}
}
}
const T* d_out_;
const int64_t* out_stride_;
const int64_t* x_strides_;
int64_t pos_;
int64_t dim_size_;
int64_t dim1_;
int64_t dim2_;
int64_t diag_size_;
T* d_x_;
};
template <typename T, typename Context>
void TraceGradKernel(const Context& dev_ctx,
const DenseTensor& x UNUSED,
const DenseTensor& out_grad,
int offset,
int axis1,
int axis2,
DenseTensor* in_grad) {
if (in_grad && in_grad->numel() == 0) {
dev_ctx.template Alloc<T>(in_grad);
return;
}
auto input_dims = in_grad->dims();
auto input_stride = common::stride(input_dims);
auto output_dims = out_grad.dims();
auto output_stride =
output_dims.size() == 0 ? DDim(output_dims) : common::stride(output_dims);
auto* out_data = out_grad.data<T>();
T* x_data = dev_ctx.template Alloc<T>(in_grad);
funcs::SetConstant<Context, T> set_zero;
set_zero(dev_ctx, in_grad, static_cast<T>(0.0));
auto dim1 = axis1;
auto dim2 = axis2;
auto dim1_ = dim1 < 0 ? input_dims.size() + dim1 : dim1;
auto dim2_ = dim2 < 0 ? input_dims.size() + dim2 : dim2;
auto len1 = input_dims[dim1_];
auto len2 = input_dims[dim2_];
auto stride1 = input_stride[dim1_];
auto stride2 = input_stride[dim2_];
int offset_stride = 0;
if (offset >= 0) {
offset_stride = stride2;
len2 -= offset;
} else {
offset_stride = stride1;
len1 += offset;
}
int64_t diag_size = len2 < len1 ? len2 : len1;
int64_t pos = std::abs(offset) * offset_stride;
if (diag_size > 0) {
#if defined(__NVCC__) || defined(__HIPCC__)
thrust::device_vector<int64_t> output_vec(vectorize(output_stride));
const int64_t* output_arr = thrust::raw_pointer_cast(output_vec.data());
thrust::device_vector<int64_t> input_vec(vectorize(input_stride));
const int64_t* input_arr = thrust::raw_pointer_cast(input_vec.data());
#else
const auto* output_arr = output_stride.Get();
const auto* input_arr = input_stride.Get();
#endif
funcs::ForRange<Context> for_range(dev_ctx, in_grad->numel());
TraceGradFunctor<T> functor(out_data,
output_arr,
input_arr,
pos,
input_dims.size(),
dim1_,
dim2_,
diag_size,
x_data);
for_range(functor);
}
}
} // namespace phi