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paddlepaddle--paddle/paddle/phi/kernels/cpu/viterbi_decode_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/viterbi_decode_kernel.h"
#include <algorithm>
#include <memory>
#include <string>
#include <vector>
#include "paddle/phi/backends/cpu/cpu_context.h"
#include "paddle/phi/core/kernel_registry.h"
#include "paddle/phi/core/tensor_utils.h"
#include "paddle/phi/kernels/empty_kernel.h"
#include "paddle/phi/kernels/funcs/compare_functors.h"
#include "paddle/phi/kernels/funcs/concat_and_split_functor.h"
#include "paddle/phi/kernels/funcs/elementwise_functor.h"
#include "paddle/phi/kernels/funcs/gather.h"
#include "paddle/phi/kernels/funcs/viterbi_decode_functor.h"
#include "paddle/phi/kernels/transpose_kernel.h"
namespace phi {
template <typename Context, typename T, typename IndType>
struct Argmax {
void operator()(const Context& dev_ctx UNUSED,
const DenseTensor& input,
DenseTensor* out_idx,
DenseTensor* out,
int axis) {
DDim input_dims = input.dims();
int64_t pre = 1;
int64_t post = 1;
int64_t n = input_dims[axis];
for (int i = 0; i < axis; i++) {
pre *= input_dims[i];
}
for (int i = axis + 1; i < input_dims.size(); i++) {
post *= input_dims[i];
}
int64_t height = pre * post;
int64_t width = n;
const T* in_data = input.data<T>();
IndType* out_idx_data = out_idx->data<IndType>();
T* out_data = out->data<T>();
// Reduce
#ifdef PADDLE_WITH_MKLML
#pragma omp parallel for
#endif
for (int64_t i = 0; i < height; ++i) {
int64_t h = i / post;
int64_t w = i % post;
IndType max_idx = -1;
T max_value = (std::numeric_limits<T>::lowest)(); // for windows compile
for (int64_t j = 0; j < width; ++j) {
if (in_data[h * width * post + j * post + w] > max_value) {
max_value = in_data[h * width * post + j * post + w];
max_idx = j;
}
}
out_data[i] = max_value;
out_idx_data[i] = max_idx;
}
}
};
template <typename Context>
struct ARange {
void operator()(const Context& dev_ctx,
int64_t* data,
int end,
int64_t scale) {
for (int i = 0; i < end; ++i) {
data[i] = i * scale;
}
}
};
template <typename Context, typename T>
struct GetMaxValue {
void operator()(const Context& dev_ctx,
const DenseTensor& input,
T* max_value) {
auto input_ptr = input.data<T>();
auto num = input.numel();
*max_value = *std::max_element(input_ptr, input_ptr + num);
}
};
template <typename Context, typename T, typename IndexT = int>
struct Gather {
void operator()(const Context& dev_ctx,
const DenseTensor& src,
const DenseTensor& index,
DenseTensor* output) {
funcs::CPUGather<T, IndexT>(dev_ctx, src, index, output);
}
};
template <typename Context,
template <typename InT, typename OutT>
class CompareFunctor,
typename T>
struct GetMask {
void operator()(const Context& dev_ctx UNUSED,
const DenseTensor& lhs,
const DenseTensor& rhs,
DenseTensor* mask) {
funcs::SameDimsBinaryOP<int64_t, CompareFunctor<int64_t, T>, T>(
lhs, rhs, mask);
}
};
template <typename Context,
template <typename T>
class BinaryFunctor,
typename T>
struct BinaryOperation {
void operator()(const Context& dev_ctx UNUSED,
const DenseTensor& lhs,
const DenseTensor& rhs,
DenseTensor* output) {
if (lhs.dims() == rhs.dims()) {
funcs::SameDimsBinaryOP<T, BinaryFunctor<T>>(lhs, rhs, output);
} else {
bool is_multi_threads = false;
#ifdef PADDLE_WITH_MKLML
if (omp_get_max_threads() > 1) {
is_multi_threads = true;
}
#endif
if (is_multi_threads) {
funcs::SimpleBroadcastBinaryOP<T, BinaryFunctor<T>, true>(
lhs, rhs, output);
} else {
funcs::SimpleBroadcastBinaryOP<T, BinaryFunctor<T>, false>(
lhs, rhs, output);
}
}
}
};
template <typename T, typename Context>
void ViterbiDecodeKernel(const Context& dev_ctx,
const DenseTensor& input,
const DenseTensor& transition,
const DenseTensor& length,
bool include_bos_eos_tag,
DenseTensor* scores,
DenseTensor* path) {
auto curr_place = dev_ctx.GetPlace();
auto batch_size = static_cast<int>(input.dims()[0]);
auto seq_len = static_cast<int>(input.dims()[1]);
auto n_labels = static_cast<int>(input.dims()[2]);
funcs::SetConstant<Context, T> float_functor;
funcs::SetConstant<Context, int64_t> int_functor;
std::vector<DenseTensor> historys;
// We create tensor buffer in order to avoid allocating memory frequently
// 10 means allocate 10*batch_size bytes memory, such as int_mask, zero...
int64_t buffer_size =
static_cast<int64_t>(batch_size) * (n_labels + 1) * seq_len +
10 * batch_size;
DenseTensor int_buffer = Empty<int64_t>(dev_ctx, {buffer_size});
funcs::TensorBuffer int_tensor_buffer(int_buffer);
// create float tensor buffer
// 10 means allocate 10*batch_size*n_labels bytes, such as alpha, alpha_max
buffer_size = static_cast<int64_t>(batch_size) * (seq_len + 10) * n_labels +
static_cast<int64_t>(batch_size + 2) * n_labels * n_labels;
DenseTensor float_buffer = Empty<T>(dev_ctx, {buffer_size});
funcs::TensorBuffer float_tensor_buffer(float_buffer);
DenseTensor left_length = int_tensor_buffer.GetBufferBlock({batch_size, 1});
Copy(dev_ctx, length, curr_place, false, &left_length);
int64_t max_seq_len = 0;
GetMaxValue<Context, int64_t> get_max_value;
get_max_value(dev_ctx, left_length, &max_seq_len);
dev_ctx.template Alloc<T>(scores);
path->Resize({batch_size, max_seq_len});
dev_ctx.template Alloc<int64_t>(path);
DenseTensor tpath =
int_tensor_buffer.GetBufferBlock({max_seq_len, batch_size});
auto batch_path = funcs::Unbind(tpath);
for (auto& item : batch_path) {
item.Resize({batch_size});
}
// create and init required tensor
DenseTensor input_exp =
float_tensor_buffer.GetBufferBlock({seq_len, batch_size, n_labels});
TransposeKernel<T, Context>(dev_ctx, input, {1, 0, 2}, &input_exp);
DenseTensor trans_exp =
float_tensor_buffer.GetBufferBlock({n_labels, n_labels});
Copy(dev_ctx, transition, curr_place, false, &trans_exp);
trans_exp.Resize({1, n_labels, n_labels});
DenseTensor alpha =
float_tensor_buffer.GetBufferBlock({batch_size, n_labels});
DenseTensor zero = int_tensor_buffer.GetBufferBlock({batch_size, 1});
int_functor(dev_ctx, &zero, static_cast<int64_t>(0));
DenseTensor one = int_tensor_buffer.GetBufferBlock({batch_size, 1});
int_functor(dev_ctx, &one, static_cast<int64_t>(1));
DenseTensor float_one = float_tensor_buffer.GetBufferBlock({batch_size, 1});
float_functor(dev_ctx, &float_one, static_cast<T>(1.0));
DenseTensor alpha_trn_sum =
float_tensor_buffer.GetBufferBlock({batch_size, n_labels, n_labels});
DenseTensor alpha_max =
float_tensor_buffer.GetBufferBlock({batch_size, n_labels});
DenseTensor alpha_argmax =
int_tensor_buffer.GetBufferBlock({seq_len, batch_size, n_labels});
auto alpha_argmax_unbind = funcs::Unbind(alpha_argmax);
DenseTensor alpha_nxt =
float_tensor_buffer.GetBufferBlock({batch_size, n_labels});
DenseTensor int_mask = int_tensor_buffer.GetBufferBlock({batch_size});
DenseTensor zero_len_mask = int_tensor_buffer.GetBufferBlock({batch_size});
DenseTensor float_mask = float_tensor_buffer.GetBufferBlock({batch_size, 1});
DenseTensor stop_trans = float_tensor_buffer.GetBufferBlock({1, 1, n_labels});
DenseTensor start_trans =
float_tensor_buffer.GetBufferBlock({1, 1, n_labels});
DenseTensor rest_trans =
float_tensor_buffer.GetBufferBlock({1, n_labels - 2, n_labels});
DenseTensor last_ids = int_tensor_buffer.GetBufferBlock({batch_size});
DenseTensor last_ids_tmp = int_tensor_buffer.GetBufferBlock({batch_size});
DenseTensor batch_offset = int_tensor_buffer.GetBufferBlock({batch_size});
DenseTensor gather_idx = int_tensor_buffer.GetBufferBlock({batch_size});
std::vector<const DenseTensor*> shape{&rest_trans, &stop_trans, &start_trans};
std::vector<DenseTensor*> outputs{&rest_trans, &stop_trans, &start_trans};
funcs::SplitFunctor<Context, T> split_functor;
split_functor(dev_ctx, trans_exp, shape, 1, &outputs);
stop_trans.Resize({1, n_labels});
start_trans.Resize({1, n_labels});
auto logit0 = input_exp.Slice(0, 1);
logit0.Resize({batch_size, n_labels});
BinaryOperation<Context, funcs::AddFunctor, T> AddFloat;
BinaryOperation<Context, funcs::AddFunctor, int64_t> AddInt;
BinaryOperation<Context, funcs::MultiplyFunctor, T> MulFloat;
BinaryOperation<Context, funcs::MultiplyFunctor, int64_t> MulInt;
BinaryOperation<Context, funcs::SubtractFunctor, T> SubFloat;
BinaryOperation<Context, funcs::SubtractFunctor, int64_t> SubInt;
if (include_bos_eos_tag) {
AddFloat(dev_ctx, logit0, start_trans, &alpha);
GetMask<Context, funcs::EqualFunctor, T>()(
dev_ctx, left_length, one, &float_mask);
MulFloat(dev_ctx, stop_trans, float_mask, &alpha_nxt);
AddFloat(dev_ctx, alpha, alpha_nxt, &alpha);
} else {
alpha = logit0;
}
SubInt(dev_ctx, left_length, one, &left_length);
Argmax<Context, T, int64_t> argmax;
for (int64_t i = 1; i < max_seq_len; ++i) {
DenseTensor logit = input_exp.Slice(i, i + 1);
logit.Resize({batch_size, n_labels});
DenseTensor& alpha_exp = alpha.Resize({batch_size, n_labels, 1});
AddFloat(dev_ctx, alpha_exp, trans_exp, &alpha_trn_sum);
auto alpha_argmax_temp = alpha_argmax_unbind[i - 1];
alpha_argmax_temp.Resize({batch_size, n_labels});
argmax(dev_ctx, alpha_trn_sum, &alpha_argmax_temp, &alpha_max, 1);
historys.emplace_back(alpha_argmax_temp);
AddFloat(dev_ctx, alpha_max, logit, &alpha_nxt);
alpha.Resize({batch_size, n_labels});
GetMask<Context, funcs::GreaterThanFunctor, T>()(
dev_ctx, left_length, zero, &float_mask);
MulFloat(dev_ctx, alpha_nxt, float_mask, &alpha_nxt);
SubFloat(dev_ctx, float_one, float_mask, &float_mask);
MulFloat(dev_ctx, alpha, float_mask, &alpha);
AddFloat(dev_ctx, alpha, alpha_nxt, &alpha);
if (include_bos_eos_tag) {
GetMask<Context, funcs::EqualFunctor, T>()(
dev_ctx, left_length, one, &float_mask);
MulFloat(dev_ctx, stop_trans, float_mask, &alpha_nxt);
AddFloat(dev_ctx, alpha, alpha_nxt, &alpha);
}
SubInt(dev_ctx, left_length, one, &left_length);
}
argmax(dev_ctx, alpha, &last_ids, scores, 1);
left_length.Resize({batch_size});
GetMask<Context, funcs::GreaterEqualFunctor, int64_t>()(
dev_ctx, left_length, zero, &int_mask);
// last_ids_update = last_ids * tag_mask
int last_ids_index = 1;
int actual_len = (std::min)(seq_len, static_cast<int>(max_seq_len));
MulInt(dev_ctx, last_ids, int_mask, &batch_path[actual_len - last_ids_index]);
// The algorithm below can refer to
// https://github.com/PaddlePaddle/PaddleNLP/blob/develop/paddlenlp/layers/crf.py#L438
ARange<Context> arange;
arange(dev_ctx, batch_offset.data<int64_t>(), batch_size, n_labels);
Gather<Context, int64_t, int64_t> gather;
for (auto hist = historys.rbegin(); hist != historys.rend(); ++hist) {
++last_ids_index;
AddInt(dev_ctx, left_length, one, &left_length);
AddInt(dev_ctx, batch_offset, last_ids, &gather_idx);
DenseTensor& last_ids_update = batch_path[actual_len - last_ids_index];
hist->Resize({batch_size * n_labels});
gather(dev_ctx, *hist, gather_idx, &last_ids_update);
GetMask<Context, funcs::GreaterThanFunctor, int64_t>()(
dev_ctx, left_length, zero, &int_mask);
MulInt(dev_ctx, last_ids_update, int_mask, &last_ids_update);
GetMask<Context, funcs::EqualFunctor, int64_t>()(
dev_ctx, left_length, zero, &zero_len_mask);
MulInt(dev_ctx, last_ids, zero_len_mask, &last_ids_tmp);
SubInt(dev_ctx, one, zero_len_mask, &zero_len_mask);
MulInt(dev_ctx, last_ids_update, zero_len_mask, &last_ids_update);
AddInt(dev_ctx, last_ids_update, last_ids_tmp, &last_ids_update);
GetMask<Context, funcs::LessThanFunctor, int64_t>()(
dev_ctx, left_length, zero, &int_mask);
MulInt(dev_ctx, last_ids, int_mask, &last_ids);
AddInt(dev_ctx, last_ids_update, last_ids, &last_ids);
}
TransposeKernel<int64_t, Context>(dev_ctx, tpath, {1, 0}, path);
}
} // namespace phi
PD_REGISTER_KERNEL(
viterbi_decode, CPU, ALL_LAYOUT, phi::ViterbiDecodeKernel, float, double) {
kernel->OutputAt(1).SetDataType(phi::DataType::INT64);
}