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Stockfish/src/eval/nnue/trainer/trainer_affine_transform.h

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// NNUE評価関数の学習クラステンプレートのAffineTransform用特殊化
#ifndef _NNUE_TRAINER_AFFINE_TRANSFORM_H_
#define _NNUE_TRAINER_AFFINE_TRANSFORM_H_
#if defined(EVAL_LEARN) && defined(EVAL_NNUE)
#include "../../../learn/learn.h"
#include "../layers/affine_transform.h"
#include "trainer.h"
#include <random>
namespace Eval {
namespace NNUE {
// 学習:アフィン変換層
template <typename PreviousLayer, IndexType OutputDimensions>
class Trainer<Layers::AffineTransform<PreviousLayer, OutputDimensions>> {
private:
// 学習対象の層の型
using LayerType = Layers::AffineTransform<PreviousLayer, OutputDimensions>;
public:
// ファクトリ関数
static std::shared_ptr<Trainer> Create(
LayerType* target_layer, FeatureTransformer* feature_transformer) {
return std::shared_ptr<Trainer>(
new Trainer(target_layer, feature_transformer));
}
// ハイパーパラメータなどのオプションを設定する
void SendMessage(Message* message) {
previous_layer_trainer_->SendMessage(message);
if (ReceiveMessage("momentum", message)) {
momentum_ = static_cast<LearnFloatType>(std::stod(message->value));
}
if (ReceiveMessage("learning_rate_scale", message)) {
learning_rate_scale_ =
static_cast<LearnFloatType>(std::stod(message->value));
}
if (ReceiveMessage("reset", message)) {
DequantizeParameters();
}
if (ReceiveMessage("quantize_parameters", message)) {
QuantizeParameters();
}
}
// パラメータを乱数で初期化する
template <typename RNG>
void Initialize(RNG& rng) {
previous_layer_trainer_->Initialize(rng);
if (kIsOutputLayer) {
// 出力層は0で初期化する
std::fill(std::begin(biases_), std::end(biases_),
static_cast<LearnFloatType>(0.0));
std::fill(std::begin(weights_), std::end(weights_),
static_cast<LearnFloatType>(0.0));
} else {
// 入力の分布が各ユニット平均0.5、等分散であることを仮定し、
// 出力の分布が各ユニット平均0.5、入力と同じ等分散になるように初期化する
const double kSigma = 1.0 / std::sqrt(kInputDimensions);
auto distribution = std::normal_distribution<double>(0.0, kSigma);
for (IndexType i = 0; i < kOutputDimensions; ++i) {
double sum = 0.0;
for (IndexType j = 0; j < kInputDimensions; ++j) {
const auto weight = static_cast<LearnFloatType>(distribution(rng));
weights_[kInputDimensions * i + j] = weight;
sum += weight;
}
biases_[i] = static_cast<LearnFloatType>(0.5 - 0.5 * sum);
}
}
QuantizeParameters();
}
// 順伝播
const LearnFloatType* Propagate(const std::vector<Example>& batch) {
if (output_.size() < kOutputDimensions * batch.size()) {
output_.resize(kOutputDimensions * batch.size());
gradients_.resize(kInputDimensions * batch.size());
}
batch_size_ = static_cast<IndexType>(batch.size());
batch_input_ = previous_layer_trainer_->Propagate(batch);
#if defined(USE_BLAS)
for (IndexType b = 0; b < batch_size_; ++b) {
const IndexType batch_offset = kOutputDimensions * b;
cblas_scopy(kOutputDimensions, biases_, 1, &output_[batch_offset], 1);
}
cblas_sgemm(CblasColMajor, CblasTrans, CblasNoTrans,
kOutputDimensions, batch_size_, kInputDimensions, 1.0,
weights_, kInputDimensions,
batch_input_, kInputDimensions,
1.0, &output_[0], kOutputDimensions);
#else
for (IndexType b = 0; b < batch_size_; ++b) {
const IndexType input_batch_offset = kInputDimensions * b;
const IndexType output_batch_offset = kOutputDimensions * b;
for (IndexType i = 0; i < kOutputDimensions; ++i) {
double sum = biases_[i];
for (IndexType j = 0; j < kInputDimensions; ++j) {
const IndexType index = kInputDimensions * i + j;
sum += weights_[index] * batch_input_[input_batch_offset + j];
}
output_[output_batch_offset + i] = static_cast<LearnFloatType>(sum);
}
}
#endif
return output_.data();
}
// 逆伝播
void Backpropagate(const LearnFloatType* gradients,
LearnFloatType learning_rate) {
const LearnFloatType local_learning_rate =
learning_rate * learning_rate_scale_;
#if defined(USE_BLAS)
// backpropagate
cblas_sgemm(CblasColMajor, CblasNoTrans, CblasNoTrans,
kInputDimensions, batch_size_, kOutputDimensions, 1.0,
weights_, kInputDimensions,
gradients, kOutputDimensions,
0.0, &gradients_[0], kInputDimensions);
// update
cblas_sscal(kOutputDimensions, momentum_, biases_diff_, 1);
for (IndexType b = 0; b < batch_size_; ++b) {
const IndexType batch_offset = kOutputDimensions * b;
cblas_saxpy(kOutputDimensions, 1.0,
&gradients[batch_offset], 1, biases_diff_, 1);
}
cblas_saxpy(kOutputDimensions, -local_learning_rate,
biases_diff_, 1, biases_, 1);
cblas_sgemm(CblasRowMajor, CblasTrans, CblasNoTrans,
kOutputDimensions, kInputDimensions, batch_size_, 1.0,
gradients, kOutputDimensions,
batch_input_, kInputDimensions,
momentum_, weights_diff_, kInputDimensions);
cblas_saxpy(kOutputDimensions * kInputDimensions, -local_learning_rate,
weights_diff_, 1, weights_, 1);
#else
// backpropagate
for (IndexType b = 0; b < batch_size_; ++b) {
const IndexType input_batch_offset = kInputDimensions * b;
const IndexType output_batch_offset = kOutputDimensions * b;
for (IndexType j = 0; j < kInputDimensions; ++j) {
double sum = 0.0;
for (IndexType i = 0; i < kOutputDimensions; ++i) {
const IndexType index = kInputDimensions * i + j;
sum += weights_[index] * gradients[output_batch_offset + i];
}
gradients_[input_batch_offset + j] = static_cast<LearnFloatType>(sum);
}
}
// update
for (IndexType i = 0; i < kOutputDimensions; ++i) {
biases_diff_[i] *= momentum_;
}
for (IndexType i = 0; i < kOutputDimensions * kInputDimensions; ++i) {
weights_diff_[i] *= momentum_;
}
for (IndexType b = 0; b < batch_size_; ++b) {
const IndexType input_batch_offset = kInputDimensions * b;
const IndexType output_batch_offset = kOutputDimensions * b;
for (IndexType i = 0; i < kOutputDimensions; ++i) {
biases_diff_[i] += gradients[output_batch_offset + i];
}
for (IndexType i = 0; i < kOutputDimensions; ++i) {
for (IndexType j = 0; j < kInputDimensions; ++j) {
const IndexType index = kInputDimensions * i + j;
weights_diff_[index] += gradients[output_batch_offset + i] *
batch_input_[input_batch_offset + j];
}
}
}
for (IndexType i = 0; i < kOutputDimensions; ++i) {
biases_[i] -= local_learning_rate * biases_diff_[i];
}
for (IndexType i = 0; i < kOutputDimensions * kInputDimensions; ++i) {
weights_[i] -= local_learning_rate * weights_diff_[i];
}
#endif
previous_layer_trainer_->Backpropagate(gradients_.data(), learning_rate);
}
private:
// コンストラクタ
Trainer(LayerType* target_layer, FeatureTransformer* feature_transformer) :
batch_size_(0),
batch_input_(nullptr),
previous_layer_trainer_(Trainer<PreviousLayer>::Create(
&target_layer->previous_layer_, feature_transformer)),
target_layer_(target_layer),
biases_(),
weights_(),
biases_diff_(),
weights_diff_(),
momentum_(0.0),
learning_rate_scale_(1.0) {
DequantizeParameters();
}
// 重みの飽和とパラメータの整数化
void QuantizeParameters() {
for (IndexType i = 0; i < kOutputDimensions * kInputDimensions; ++i) {
weights_[i] = std::max(-kMaxWeightMagnitude,
std::min(+kMaxWeightMagnitude, weights_[i]));
}
for (IndexType i = 0; i < kOutputDimensions; ++i) {
target_layer_->biases_[i] =
Round<typename LayerType::BiasType>(biases_[i] * kBiasScale);
}
for (IndexType i = 0; i < kOutputDimensions; ++i) {
const auto offset = kInputDimensions * i;
const auto padded_offset = LayerType::kPaddedInputDimensions * i;
for (IndexType j = 0; j < kInputDimensions; ++j) {
target_layer_->weights_[padded_offset + j] =
Round<typename LayerType::WeightType>(
weights_[offset + j] * kWeightScale);
}
}
}
// 整数化されたパラメータの読み込み
void DequantizeParameters() {
for (IndexType i = 0; i < kOutputDimensions; ++i) {
biases_[i] = static_cast<LearnFloatType>(
target_layer_->biases_[i] / kBiasScale);
}
for (IndexType i = 0; i < kOutputDimensions; ++i) {
const auto offset = kInputDimensions * i;
const auto padded_offset = LayerType::kPaddedInputDimensions * i;
for (IndexType j = 0; j < kInputDimensions; ++j) {
weights_[offset + j] = static_cast<LearnFloatType>(
target_layer_->weights_[padded_offset + j] / kWeightScale);
}
}
std::fill(std::begin(biases_diff_), std::end(biases_diff_),
static_cast<LearnFloatType>(0.0));
std::fill(std::begin(weights_diff_), std::end(weights_diff_),
static_cast<LearnFloatType>(0.0));
}
// 入出力の次元数
static constexpr IndexType kInputDimensions = LayerType::kInputDimensions;
static constexpr IndexType kOutputDimensions = LayerType::kOutputDimensions;
// 出力の次元数が1なら出力層
static constexpr bool kIsOutputLayer = kOutputDimensions == 1;
// パラメータの整数化で用いる係数
static constexpr LearnFloatType kActivationScale =
std::numeric_limits<std::int8_t>::max();
static constexpr LearnFloatType kBiasScale = kIsOutputLayer ?
(kPonanzaConstant * FV_SCALE) :
((1 << kWeightScaleBits) * kActivationScale);
static constexpr LearnFloatType kWeightScale = kBiasScale / kActivationScale;
// パラメータの整数化でオーバーフローさせないために用いる重みの絶対値の上限
static constexpr LearnFloatType kMaxWeightMagnitude =
std::numeric_limits<typename LayerType::WeightType>::max() / kWeightScale;
// ミニバッチのサンプル数
IndexType batch_size_;
// ミニバッチの入力
const LearnFloatType* batch_input_;
// 直前の層のTrainer
const std::shared_ptr<Trainer<PreviousLayer>> previous_layer_trainer_;
// 学習対象の層
LayerType* const target_layer_;
// パラメータ
LearnFloatType biases_[kOutputDimensions];
LearnFloatType weights_[kOutputDimensions * kInputDimensions];
// パラメータの更新で用いるバッファ
LearnFloatType biases_diff_[kOutputDimensions];
LearnFloatType weights_diff_[kOutputDimensions * kInputDimensions];
// 順伝播用バッファ
std::vector<LearnFloatType> output_;
// 逆伝播用バッファ
std::vector<LearnFloatType> gradients_;
// ハイパーパラメータ
LearnFloatType momentum_;
LearnFloatType learning_rate_scale_;
};
} // namespace NNUE
} // namespace Eval
#endif // defined(EVAL_LEARN) && defined(EVAL_NNUE)
#endif