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paddlepaddle--paddle/paddle/phi/kernels/cpu/embedding_grad_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/embedding_grad_kernel.h"
#include "paddle/phi/backends/cpu/cpu_context.h"
#include "paddle/phi/common/data_type.h"
#include "paddle/phi/core/kernel_registry.h"
#include "paddle/phi/kernels/funcs/embedding_util.h"
namespace phi {
template <typename T, typename Context>
struct EmbeddingGradCPUFunctor {
EmbeddingGradCPUFunctor(const Context& dev_ctx,
const DenseTensor& input,
const DenseTensor& weight,
const DenseTensor& out_grad,
int64_t padding_idx,
DenseTensor* weight_grad)
: dev_ctx_(dev_ctx),
input_(input),
weight_(weight),
out_grad_(out_grad),
weight_grad_(weight_grad),
padding_idx_(padding_idx) {}
template <typename IdT>
void apply() {
DDim table_dim = weight_.dims();
auto ids = CopyIdsToVector<IdT, int64_t>(input_);
auto ids_num = static_cast<int64_t>(ids.size());
// Since paddings are not trainable and fixed in forward, the gradient of
// paddings makes no sense and we don't deal with it in backward.
{
auto* d_output = &out_grad_;
auto* ids_data = ids.data();
int64_t N = table_dim[0];
int64_t D = table_dim[1];
auto* d_output_data = d_output->template data<T>();
dev_ctx_.template Alloc<T>(weight_grad_);
auto* d_table_data = weight_grad_->data<T>();
memset(d_table_data, 0, weight_grad_->numel() * sizeof(T));
for (int64_t i = 0; i < ids_num; ++i) {
if (padding_idx_ != kNoPadding && ids_data[i] == padding_idx_) {
// the gradient of padding_idx should be 0, already done by memset, so
// do nothing.
} else {
PADDLE_ENFORCE_LT(
ids_data[i],
N,
common::errors::InvalidArgument(
"Variable value (input) of "
"OP(paddle.nn.functional.embedding) "
"expected >= 0 and < %ld, but got %ld. Please check input "
"value.",
N,
ids_data[i]));
PADDLE_ENFORCE_GE(
ids_data[i],
0,
common::errors::InvalidArgument(
"Variable value (input) of "
"OP(paddle.nn.functional.embedding) "
"expected >= 0 and < %ld, but got %ld. Please check input "
"value.",
N,
ids_data[i]));
for (int j = 0; j < D; ++j) {
d_table_data[ids_data[i] * D + j] += d_output_data[i * D + j];
}
}
}
}
}
private:
const Context& dev_ctx_;
const DenseTensor& input_;
const DenseTensor& weight_;
const DenseTensor& out_grad_;
DenseTensor* weight_grad_;
int64_t padding_idx_;
};
template <typename T, typename Context>
void EmbeddingGradKernel(const Context& dev_ctx,
const DenseTensor& input,
const DenseTensor& weight,
const DenseTensor& out_grad,
int64_t padding_idx,
DenseTensor* weight_grad) {
EmbeddingGradCPUFunctor<T, Context> functor(
dev_ctx, input, weight, out_grad, padding_idx, weight_grad);
if (input.dtype() == DataType::INT32) {
functor.template apply<int>();
} else if (input.dtype() == DataType::INT64) {
functor.template apply<int64_t>();
} else {
PADDLE_THROW(common::errors::Unimplemented(
"embedding input only support int32 and int64"));
}
}
template <typename T, typename Context>
struct EmbeddingSparseGradCPUFunctor {
EmbeddingSparseGradCPUFunctor(const Context& dev_ctx,
const DenseTensor& input,
const DenseTensor& weight,
const DenseTensor& out_grad,
int64_t padding_idx,
SelectedRows* weight_grad)
: dev_ctx_(dev_ctx),
input_(input),
weight_(weight),
out_grad_(out_grad),
weight_grad_(weight_grad),
padding_idx_(padding_idx) {}
template <typename IdT>
void apply() {
DDim table_dim = weight_.dims();
auto ids = CopyIdsToVector<IdT, int64_t>(input_);
auto ids_num = static_cast<int64_t>(ids.size());
// Since paddings are not trainable and fixed in forward, the gradient of
// paddings makes no sense and we don't deal with it in backward.
auto* d_table = weight_grad_;
auto* d_output = &out_grad_;
d_table->set_rows(ids);
auto* d_table_value = d_table->mutable_value();
d_table_value->Resize({ids_num, table_dim[1]});
dev_ctx_.template Alloc<T>(d_table_value);
d_table->set_height(table_dim[0]);
auto* d_output_data = d_output->template data<T>();
auto* d_table_data = d_table_value->template data<T>();
auto d_output_dims = d_output->dims();
auto d_output_dims_2d =
flatten_to_2d(d_output_dims, d_output_dims.size() - 1);
PADDLE_ENFORCE_EQ(d_table_value->dims(),
d_output_dims_2d,
common::errors::InvalidArgument(
"ShapeError: The shape of lookup_table@Grad and "
"output@Grad should be same. "
"But received lookup_table@Grad's shape = [%s], "
"output@Grad's shape = [%s].",
d_table_value->dims(),
d_output_dims_2d));
memcpy(d_table_data, d_output_data, sizeof(T) * d_output->numel());
}
private:
const Context& dev_ctx_;
const DenseTensor& input_;
const DenseTensor& weight_;
const DenseTensor& out_grad_;
SelectedRows* weight_grad_;
int64_t padding_idx_;
};
template <typename T, typename Context>
void EmbeddingSparseGradKernel(const Context& dev_ctx,
const DenseTensor& input,
const DenseTensor& weight,
const DenseTensor& out_grad,
int64_t padding_idx,
SelectedRows* weight_grad) {
EmbeddingSparseGradCPUFunctor<T, Context> functor(
dev_ctx, input, weight, out_grad, padding_idx, weight_grad);
if (input.dtype() == DataType::INT32) {
functor.template apply<int>();
} else if (input.dtype() == DataType::INT64) {
functor.template apply<int64_t>();
} else {
PADDLE_THROW(common::errors::Unimplemented(
"embedding input only support int32 and int64"));
}
}
} // namespace phi
PD_REGISTER_KERNEL(embedding_grad,
CPU,
ALL_LAYOUT,
phi::EmbeddingGradKernel,
float,
double,
phi::float16,
phi::bfloat16,
phi::complex64,
phi::complex128) {}
PD_REGISTER_KERNEL(embedding_sparse_grad,
CPU,
ALL_LAYOUT,
phi::EmbeddingSparseGradKernel,
float,
double,
phi::bfloat16,
phi::complex64,
phi::complex128) {}