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BadFish/src/eval/nnue/trainer/trainer_affine_transform.h
FireFather aea08de018 Translation
Files in /eval, /extra, & /learn - comments translated from Japanese to English
2020-06-28 03:12:55 +02:00

301 lines
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C++

// Specialization of NNUE evaluation function learning class template for AffineTransform
#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 {
// Learning: Affine transformation layer
template <typename PreviousLayer, IndexType OutputDimensions>
class Trainer<Layers::AffineTransform<PreviousLayer, OutputDimensions>> {
private:
// Type of layer to learn
using LayerType = Layers::AffineTransform<PreviousLayer, OutputDimensions>;
public:
// factory function
static std::shared_ptr<Trainer> Create(
LayerType* target_layer, FeatureTransformer* feature_transformer) {
return std::shared_ptr<Trainer>(
new Trainer(target_layer, feature_transformer));
}
// Set options such as hyperparameters
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();
}
}
// Initialize the parameters with random numbers
template <typename RNG>
void Initialize(RNG& rng) {
previous_layer_trainer_->Initialize(rng);
if (kIsOutputLayer) {
// Initialize output layer with 0
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 {
// Assuming that the input distribution is unit-mean 0.5, equal variance,
// Initialize the output distribution so that each unit has a mean of 0.5 and the same variance as the input
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();
}
// forward propagation
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();
}
// backpropagation
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:
// constructor
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();
}
// Weight saturation and parameterization
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);
}
}
}
// read parameterized integer
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));
}
// number of input/output dimensions
static constexpr IndexType kInputDimensions = LayerType::kInputDimensions;
static constexpr IndexType kOutputDimensions = LayerType::kOutputDimensions;
// If the output dimensionality is 1, the output layer
static constexpr bool kIsOutputLayer = kOutputDimensions == 1;
// Coefficient used for parameterization
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;
// Upper limit of absolute value of weight used to prevent overflow when parameterizing integers
static constexpr LearnFloatType kMaxWeightMagnitude =
std::numeric_limits<typename LayerType::WeightType>::max() / kWeightScale;
// number of samples in mini-batch
IndexType batch_size_;
// Input mini batch
const LearnFloatType* batch_input_;
// Trainer of the previous layer
const std::shared_ptr<Trainer<PreviousLayer>> previous_layer_trainer_;
// layer to learn
LayerType* const target_layer_;
// parameter
LearnFloatType biases_[kOutputDimensions];
LearnFloatType weights_[kOutputDimensions * kInputDimensions];
// Buffer used for updating parameters
LearnFloatType biases_diff_[kOutputDimensions];
LearnFloatType weights_diff_[kOutputDimensions * kInputDimensions];
// Forward propagation buffer
std::vector<LearnFloatType> output_;
// buffer for back propagation
std::vector<LearnFloatType> gradients_;
// hyper parameter
LearnFloatType momentum_;
LearnFloatType learning_rate_scale_;
};
} // namespace NNUE
} // namespace Eval
#endif // defined(EVAL_LEARN) && defined(EVAL_NNUE)
#endif