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paddlepaddle--paddle/paddle/phi/kernels/cpu/nonzero_kernel.cc
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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/nonzero_kernel.h"
#include "paddle/phi/core/dense_tensor.h"
#include "paddle/phi/core/kernel_registry.h"
#include "paddle/phi/kernels/funcs/for_range.h"
#include "paddle/phi/kernels/funcs/math_function.h"
namespace phi {
template <typename T>
struct WhereIndexFunctor {
WhereIndexFunctor(
const T* true_index, int true_num, const T* stride, int rank, T* out)
: true_index_(true_index),
true_num_(true_num),
stride_(stride),
rank_(rank),
out_ptr_(out) {}
HOSTDEVICE void operator()(size_t idx) const {
T index = true_index_[idx];
for (int j = 0; j < rank_; j++) {
out_ptr_[idx * rank_ + j] = index / stride_[j];
index -= out_ptr_[idx * rank_ + j] * stride_[j];
}
}
const T* true_index_;
int true_num_;
const T* stride_;
int rank_;
T* out_ptr_;
};
template <typename T, typename Context>
void NonZeroKernel(const Context& dev_ctx,
const DenseTensor& condition,
DenseTensor* out) {
const T* cond_data = condition.data<T>();
auto numel = condition.numel();
auto dims = condition.dims();
const int rank = dims.size();
if (numel == 0) {
dev_ctx.template Alloc<int64_t>(out);
return;
}
std::vector<int64_t> true_index;
for (auto i = 0; i < numel; i++) {
if (static_cast<bool>(cond_data[i])) {
true_index.push_back(i);
}
}
auto true_num = true_index.size();
out->Resize({static_cast<int64_t>(true_num), rank});
auto* out_ptr = dev_ctx.template Alloc<int64_t>(out);
if (true_num == 0) {
return;
}
std::vector<int64_t> stride(rank);
stride[rank - 1] = 1;
for (int i = rank - 2; i >= 0; i--) {
stride[i] = stride[i + 1] * dims[i + 1];
}
WhereIndexFunctor<int64_t> functor(
true_index.data(), true_num, stride.data(), rank, out_ptr);
funcs::ForRange<CPUContext> for_range(dev_ctx, true_num);
for_range(functor);
}
} // namespace phi
PD_REGISTER_KERNEL(nonzero,
CPU,
ALL_LAYOUT,
phi::NonZeroKernel,
int64_t,
int,
int16_t,
phi::bfloat16,
bool,
float,
double,
phi::complex64,
phi::complex128) {
kernel->OutputAt(0).SetDataType(phi::DataType::INT64);
}