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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.
#pragma once
#include <vector>
#include "paddle/phi/backends/dynload/warpctc.h"
#include "paddle/phi/core/dense_tensor.h"
#include "paddle/phi/kernels/empty_kernel.h"
#include "paddle/phi/kernels/funcs/eigen/common.h"
#include "paddle/phi/kernels/funcs/math_function.h"
#include "paddle/phi/kernels/funcs/sequence_padding.h"
#include "paddle/phi/kernels/funcs/sequence_scale.h"
#include "paddle/utils/optional.h"
namespace phi {
template <typename T, typename Context>
void WarpctcGradKernel(const Context& dev_ctx,
const DenseTensor& logits UNUSED,
const optional<DenseTensor>& logits_length,
const DenseTensor& warpctcgrad,
const DenseTensor& loss_grad,
int blank UNUSED,
bool norm_by_times,
DenseTensor* logits_grad) {
dev_ctx.template Alloc<T>(logits_grad);
if (logits_length.is_initialized()) {
int64_t max_seq_length = warpctcgrad.dims()[0]; // Tmax
int64_t num_sequences = warpctcgrad.dims()[1]; // B
int64_t seq_width = warpctcgrad.dims()[2]; // D
// B
auto logits_len_e = EigenTensor<int64_t, 1>::From(*logits_length);
// (B, 1)
auto loss_grad_e = EigenTensor<T, 2>::From(loss_grad);
// (T, B, D)
auto warpctcgrad_e = EigenTensor<T, 3>::From(warpctcgrad);
auto logits_grad_e = EigenTensor<T, 3>::From(*logits_grad);
Eigen::DSizes<int64_t, 3> grad_shape(1, num_sequences, 1);
Eigen::DSizes<int64_t, 3> bcast(max_seq_length, 1, seq_width);
auto logits_g =
warpctcgrad_e * loss_grad_e.reshape(grad_shape).broadcast(bcast).eval();
auto* place = dev_ctx.eigen_device();
if (norm_by_times) {
auto scales = logits_len_e.cast<T>()
.inverse()
.reshape(grad_shape)
.broadcast(bcast)
.eval();
logits_grad_e.device(*place) = logits_g * scales;
} else {
logits_grad_e.device(*place) = logits_g;
}
} else {
funcs::UnpaddingDenseTensorFunctor<Context, T>()(dev_ctx,
warpctcgrad,
logits_grad,
-1,
0,
norm_by_times,
funcs::kLengthBatchWidth);
const T* loss_grad_data = loss_grad.data<T>();
funcs::ScaleDenseTensorFunctor<Context, T>()(
dev_ctx, loss_grad_data, logits_grad);
}
}
} // namespace phi