#ifndef NNUE_FEATURE_TRANSFORMER_H_INCLUDED
#define NNUE_FEATURE_TRANSFORMER_H_INCLUDED
-#include "nnue_common.h"
+#include <algorithm>
+#include <cassert>
+#include <cstdint>
+#include <cstring>
+#include <iosfwd>
+#include <utility>
+
+#include "../position.h"
+#include "../types.h"
+#include "nnue_accumulator.h"
#include "nnue_architecture.h"
-
-#include <cstring> // std::memset()
+#include "nnue_common.h"
namespace Stockfish::Eval::NNUE {
"Per feature PSQT values cannot be processed at granularity lower than 8 at a time.");
#ifdef USE_AVX512
- typedef __m512i vec_t;
- typedef __m256i psqt_vec_t;
+ using vec_t = __m512i;
+ using psqt_vec_t = __m256i;
#define vec_load(a) _mm512_load_si512(a)
#define vec_store(a,b) _mm512_store_si512(a,b)
#define vec_add_16(a,b) _mm512_add_epi16(a,b)
#define vec_add_psqt_32(a,b) _mm256_add_epi32(a,b)
#define vec_sub_psqt_32(a,b) _mm256_sub_epi32(a,b)
#define vec_zero_psqt() _mm256_setzero_si256()
- #define NumRegistersSIMD 32
+ #define NumRegistersSIMD 16
#define MaxChunkSize 64
#elif USE_AVX2
- typedef __m256i vec_t;
- typedef __m256i psqt_vec_t;
+ using vec_t = __m256i;
+ using psqt_vec_t = __m256i;
#define vec_load(a) _mm256_load_si256(a)
#define vec_store(a,b) _mm256_store_si256(a,b)
#define vec_add_16(a,b) _mm256_add_epi16(a,b)
#define MaxChunkSize 32
#elif USE_SSE2
- typedef __m128i vec_t;
- typedef __m128i psqt_vec_t;
+ using vec_t = __m128i;
+ using psqt_vec_t = __m128i;
#define vec_load(a) (*(a))
#define vec_store(a,b) *(a)=(b)
#define vec_add_16(a,b) _mm_add_epi16(a,b)
#define NumRegistersSIMD (Is64Bit ? 16 : 8)
#define MaxChunkSize 16
- #elif USE_MMX
- typedef __m64 vec_t;
- typedef __m64 psqt_vec_t;
- #define vec_load(a) (*(a))
- #define vec_store(a,b) *(a)=(b)
- #define vec_add_16(a,b) _mm_add_pi16(a,b)
- #define vec_sub_16(a,b) _mm_sub_pi16(a,b)
- #define vec_mul_16(a,b) _mm_mullo_pi16(a,b)
- #define vec_zero() _mm_setzero_si64()
- #define vec_set_16(a) _mm_set1_pi16(a)
- inline vec_t vec_max_16(vec_t a,vec_t b){
- vec_t comparison = _mm_cmpgt_pi16(a,b);
- return _mm_or_si64(_mm_and_si64(comparison, a), _mm_andnot_si64(comparison, b));
- }
- inline vec_t vec_min_16(vec_t a,vec_t b){
- vec_t comparison = _mm_cmpgt_pi16(a,b);
- return _mm_or_si64(_mm_and_si64(comparison, b), _mm_andnot_si64(comparison, a));
- }
- #define vec_msb_pack_16(a,b) _mm_packs_pi16(_mm_srli_pi16(a,7),_mm_srli_pi16(b,7))
- #define vec_load_psqt(a) (*(a))
- #define vec_store_psqt(a,b) *(a)=(b)
- #define vec_add_psqt_32(a,b) _mm_add_pi32(a,b)
- #define vec_sub_psqt_32(a,b) _mm_sub_pi32(a,b)
- #define vec_zero_psqt() _mm_setzero_si64()
- #define vec_cleanup() _mm_empty()
- #define NumRegistersSIMD 8
- #define MaxChunkSize 8
-
#elif USE_NEON
- typedef int16x8_t vec_t;
- typedef int32x4_t psqt_vec_t;
+ using vec_t = int16x8_t;
+ using psqt_vec_t = int32x4_t;
#define vec_load(a) (*(a))
#define vec_store(a,b) *(a)=(b)
#define vec_add_16(a,b) vaddq_s16(a,b)
// Read network parameters
bool read_parameters(std::istream& stream) {
- read_little_endian<BiasType >(stream, biases , HalfDimensions );
- read_little_endian<WeightType >(stream, weights , HalfDimensions * InputDimensions);
- read_l
ittle_endian<PSQTWeightType>(stream, psqtWeights, PSQTBuckets * InputDimensions);
+ read_leb_128<BiasType >(stream, biases , HalfDimensions );
+ read_leb_128<WeightType >(stream, weights , HalfDimensions * InputDimensions);
+ read_l
eb_128<PSQTWeightType>(stream, psqtWeights, PSQTBuckets * InputDimensions);
return !stream.fail();
}
// Write network parameters
bool write_parameters(std::ostream& stream) const {
- write_little_endian<BiasType >(stream, biases , HalfDimensions );
- write_little_endian<WeightType >(stream, weights , HalfDimensions * InputDimensions);
- write_l
ittle_endian<PSQTWeightType>(stream, psqtWeights, PSQTBuckets * InputDimensions);
+ write_leb_128<BiasType >(stream, biases , HalfDimensions );
+ write_leb_128<WeightType >(stream, weights , HalfDimensions * InputDimensions);
+ write_l
eb_128<PSQTWeightType>(stream, psqtWeights, PSQTBuckets * InputDimensions);
return !stream.fail();
}
for (IndexType j = 0; j < HalfDimensions / 2; ++j) {
BiasType sum0 = accumulation[static_cast<int>(perspectives[p])][j + 0];
BiasType sum1 = accumulation[static_cast<int>(perspectives[p])][j + HalfDimensions / 2];
- sum0 = std::max<int>(0, std::min<int>(127, sum0));
- sum1 = std::max<int>(0, std::min<int>(127, sum1));
- output[offset + j] = static_cast<OutputType>(sum0 * sum1 / 128);
+ sum0 = std::clamp<BiasType>(sum0, 0, 127);
+ sum1 = std::clamp<BiasType>(sum1, 0, 127);
+ output[offset + j] = static_cast<OutputType>(unsigned(sum0 * sum1) / 128);
}
#endif
}
-#if defined(vec_cleanup)
- vec_cleanup();
-#endif
-
return psqt;
+ } // end of function transform()
- } // end of function transform()
-
-
+ void hint_common_access(const Position& pos) const {
+ hint_common_access_for_perspective<WHITE>(pos);
+ hint_common_access_for_perspective<BLACK>(pos);
+ }
private:
template<Color Perspective>
- void update_accumulator(const Position& pos) const {
-
- // The size must be enough to contain the largest possible update.
- // That might depend on the feature set and generally relies on the
- // feature set's update cost calculation to be correct and never
- // allow updates with more added/removed features than MaxActiveDimensions.
-
- #ifdef VECTOR
- // Gcc-10.2 unnecessarily spills AVX2 registers if this array
- // is defined in the VECTOR code below, once in each branch
- vec_t acc[NumRegs];
- psqt_vec_t psqt[NumPsqtRegs];
- #endif
-
+ [[nodiscard]] std::pair<StateInfo*, StateInfo*> try_find_computed_accumulator(const Position& pos) const {
// Look for a usable accumulator of an earlier position. We keep track
// of the estimated gain in terms of features to be added/subtracted.
StateInfo *st = pos.state(), *next = nullptr;
next = st;
st = st->previous;
}
+ return { st, next };
+ }
- if (st->accumulator.computed[Perspective])
- {
- if (next == nullptr)
- return;
+ // NOTE: The parameter states_to_update is an array of position states, ending with nullptr.
+ // All states must be sequential, that is states_to_update[i] must either be reachable
+ // by repeatedly applying ->previous from states_to_update[i+1] or states_to_update[i] == nullptr.
+ // computed_st must be reachable by repeatedly applying ->previous on states_to_update[0], if not nullptr.
+ template<Color Perspective, size_t N>
+ void update_accumulator_incremental(const Position& pos, StateInfo* computed_st, StateInfo* states_to_update[N]) const {
+ static_assert(N > 0);
+ assert(states_to_update[N-1] == nullptr);
- // Update incrementally in two steps. First, we update the "next"
- // accumulator. Then, we update the current accumulator (pos.state()).
+ #ifdef VECTOR
+ // Gcc-10.2 unnecessarily spills AVX2 registers if this array
+ // is defined in the VECTOR code below, once in each branch
+ vec_t acc[NumRegs];
+ psqt_vec_t psqt[NumPsqtRegs];
+ #endif
- // Gather all features to be updated.
- const Square ksq = pos.square<KING>(Perspective);
- FeatureSet::IndexList removed[2], added[2];
- FeatureSet::append_changed_indices<Perspective>(
- ksq, next->dirtyPiece, removed[0], added[0]);
- for (StateInfo *st2 = pos.state(); st2 != next; st2 = st2->previous)
- FeatureSet::append_changed_indices<Perspective>(
- ksq, st2->dirtyPiece, removed[1], added[1]);
+ if (states_to_update[0] == nullptr)
+ return;
- // Mark the accumulators as computed.
- next->accumulator.computed[Perspective] = true;
- pos.state()->accumulator.computed[Perspective] = true;
+ // Update incrementally going back through states_to_update.
- // Now update the accumulators listed in states_to_update[], where the last element is a sentinel.
- StateInfo *states_to_update[3] =
- { next, next == pos.state() ? nullptr : pos.state(), nullptr };
- #ifdef VECTOR
- for (IndexType j = 0; j < HalfDimensions / TileHeight; ++j)
- {
- // Load accumulator
- auto accTile = reinterpret_cast<vec_t*>(
- &st->accumulator.accumulation[Perspective][j * TileHeight]);
- for (IndexType k = 0; k < NumRegs; ++k)
- acc[k] = vec_load(&accTile[k]);
+ // Gather all features to be updated.
+ const Square ksq = pos.square<KING>(Perspective);
- for (IndexType i = 0; states_to_update[i]; ++i)
- {
- // Difference calculation for the deactivated features
- for (const auto index : removed[i])
- {
- const IndexType offset = HalfDimensions * index + j * TileHeight;
- auto column = reinterpret_cast<const vec_t*>(&weights[offset]);
- for (IndexType k = 0; k < NumRegs; ++k)
- acc[k] = vec_sub_16(acc[k], column[k]);
- }
-
- // Difference calculation for the activated features
- for (const auto index : added[i])
- {
- const IndexType offset = HalfDimensions * index + j * TileHeight;
- auto column = reinterpret_cast<const vec_t*>(&weights[offset]);
- for (IndexType k = 0; k < NumRegs; ++k)
- acc[k] = vec_add_16(acc[k], column[k]);
- }
-
- // Store accumulator
- accTile = reinterpret_cast<vec_t*>(
- &states_to_update[i]->accumulator.accumulation[Perspective][j * TileHeight]);
- for (IndexType k = 0; k < NumRegs; ++k)
- vec_store(&accTile[k], acc[k]);
- }
- }
+ // The size must be enough to contain the largest possible update.
+ // That might depend on the feature set and generally relies on the
+ // feature set's update cost calculation to be correct and never
+ // allow updates with more added/removed features than MaxActiveDimensions.
+ FeatureSet::IndexList removed[N-1], added[N-1];
- for (IndexType j = 0; j < PSQTBuckets / PsqtTileHeight; ++j)
- {
- // Load accumulator
- auto accTilePsqt = reinterpret_cast<psqt_vec_t*>(
- &st->accumulator.psqtAccumulation[Perspective][j * PsqtTileHeight]);
- for (std::size_t k = 0; k < NumPsqtRegs; ++k)
- psqt[k] = vec_load_psqt(&accTilePsqt[k]);
+ {
+ int i = N-2; // last potential state to update. Skip last element because it must be nullptr.
+ while (states_to_update[i] == nullptr)
+ --i;
- for (IndexType i = 0; states_to_update[i]; ++i)
- {
- // Difference calculation for the deactivated features
- for (const auto index : removed[i])
- {
- const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
- auto columnPsqt = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
- for (std::size_t k = 0; k < NumPsqtRegs; ++k)
- psqt[k] = vec_sub_psqt_32(psqt[k], columnPsqt[k]);
- }
-
- // Difference calculation for the activated features
- for (const auto index : added[i])
- {
- const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
- auto columnPsqt = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
- for (std::size_t k = 0; k < NumPsqtRegs; ++k)
- psqt[k] = vec_add_psqt_32(psqt[k], columnPsqt[k]);
- }
-
- // Store accumulator
- accTilePsqt = reinterpret_cast<psqt_vec_t*>(
- &states_to_update[i]->accumulator.psqtAccumulation[Perspective][j * PsqtTileHeight]);
- for (std::size_t k = 0; k < NumPsqtRegs; ++k)
- vec_store_psqt(&accTilePsqt[k], psqt[k]);
- }
- }
+ StateInfo *st2 = states_to_update[i];
- #else
- for (IndexType i = 0; states_to_update[i]; ++i)
+ for (; i >= 0; --i)
{
- std::memcpy(states_to_update[i]->accumulator.accumulation[Perspective],
- st->accumulator.accumulation[Perspective],
- HalfDimensions * sizeof(BiasType));
+ states_to_update[i]->accumulator.computed[Perspective] = true;
- for (std::size_t k = 0; k < PSQTBuckets; ++k)
- states_to_update[i]->accumulator.psqtAccumulation[Perspective][k] = st->accumulator.psqtAccumulation[Perspective][k];
+ StateInfo* end_state = i == 0 ? computed_st : states_to_update[i - 1];
+
+ for (; st2 != end_state; st2 = st2->previous)
+ FeatureSet::append_changed_indices<Perspective>(
+ ksq, st2->dirtyPiece, removed[i], added[i]);
+ }
+ }
- st = states_to_update[i];
+ StateInfo* st = computed_st;
+ // Now update the accumulators listed in states_to_update[], where the last element is a sentinel.
+#ifdef VECTOR
+ for (IndexType j = 0; j < HalfDimensions / TileHeight; ++j)
+ {
+ // Load accumulator
+ auto accTile = reinterpret_cast<vec_t*>(
+ &st->accumulator.accumulation[Perspective][j * TileHeight]);
+ for (IndexType k = 0; k < NumRegs; ++k)
+ acc[k] = vec_load(&accTile[k]);
+
+ for (IndexType i = 0; states_to_update[i]; ++i)
+ {
// Difference calculation for the deactivated features
for (const auto index : removed[i])
{
- const IndexType offset = HalfDimensions * index;
-
- for (IndexType j = 0; j < HalfDimensions; ++j)
- st->accumulator.accumulation[Perspective][j] -= weights[offset + j];
-
- for (std::size_t k = 0; k < PSQTBuckets; ++k)
- st->accumulator.psqtAccumulation[Perspective][k] -= psqtWeights[index * PSQTBuckets + k];
+ const IndexType offset = HalfDimensions * index + j * TileHeight;
+ auto column = reinterpret_cast<const vec_t*>(&weights[offset]);
+ for (IndexType k = 0; k < NumRegs; ++k)
+ acc[k] = vec_sub_16(acc[k], column[k]);
}
// Difference calculation for the activated features
for (const auto index : added[i])
- {
- const IndexType offset = HalfDimensions * index;
-
- for (IndexType j = 0; j < HalfDimensions; ++j)
- st->accumulator.accumulation[Perspective][j] += weights[offset + j];
-
- for (std::size_t k = 0; k < PSQTBuckets; ++k)
- st->accumulator.psqtAccumulation[Perspective][k] += psqtWeights[index * PSQTBuckets + k];
- }
- }
- #endif
- }
- else
- {
- // Refresh the accumulator
- auto& accumulator = pos.state()->accumulator;
- accumulator.computed[Perspective] = true;
- FeatureSet::IndexList active;
- FeatureSet::append_active_indices<Perspective>(pos, active);
-
- #ifdef VECTOR
- for (IndexType j = 0; j < HalfDimensions / TileHeight; ++j)
- {
- auto biasesTile = reinterpret_cast<const vec_t*>(
- &biases[j * TileHeight]);
- for (IndexType k = 0; k < NumRegs; ++k)
- acc[k] = biasesTile[k];
-
- for (const auto index : active)
{
const IndexType offset = HalfDimensions * index + j * TileHeight;
auto column = reinterpret_cast<const vec_t*>(&weights[offset]);
-
- for (unsigned k = 0; k < NumRegs; ++k)
+ for (IndexType k = 0; k < NumRegs; ++k)
acc[k] = vec_add_16(acc[k], column[k]);
}
- auto accTile = reinterpret_cast<vec_t*>(
- &accumulator.accumulation[Perspective][j * TileHeight]);
- for (unsigned k = 0; k < NumRegs; k++)
+ // Store accumulator
+ accTile = reinterpret_cast<vec_t*>(
+ &states_to_update[i]->accumulator.accumulation[Perspective][j * TileHeight]);
+ for (IndexType k = 0; k < NumRegs; ++k)
vec_store(&accTile[k], acc[k]);
}
+ }
- for (IndexType j = 0; j < PSQTBuckets / PsqtTileHeight; ++j)
- {
- for (std::size_t k = 0; k < NumPsqtRegs; ++k)
- psqt[k] = vec_zero_psqt();
+ for (IndexType j = 0; j < PSQTBuckets / PsqtTileHeight; ++j)
+ {
+ // Load accumulator
+ auto accTilePsqt = reinterpret_cast<psqt_vec_t*>(
+ &st->accumulator.psqtAccumulation[Perspective][j * PsqtTileHeight]);
+ for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+ psqt[k] = vec_load_psqt(&accTilePsqt[k]);
- for (const auto index : active)
+ for (IndexType i = 0; states_to_update[i]; ++i)
+ {
+ // Difference calculation for the deactivated features
+ for (const auto index : removed[i])
{
const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
auto columnPsqt = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
+ for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+ psqt[k] = vec_sub_psqt_32(psqt[k], columnPsqt[k]);
+ }
+ // Difference calculation for the activated features
+ for (const auto index : added[i])
+ {
+ const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
+ auto columnPsqt = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
for (std::size_t k = 0; k < NumPsqtRegs; ++k)
psqt[k] = vec_add_psqt_32(psqt[k], columnPsqt[k]);
}
- auto accTilePsqt = reinterpret_cast<psqt_vec_t*>(
- &accumulator.psqtAccumulation[Perspective][j * PsqtTileHeight]);
+ // Store accumulator
+ accTilePsqt = reinterpret_cast<psqt_vec_t*>(
+ &states_to_update[i]->accumulator.psqtAccumulation[Perspective][j * PsqtTileHeight]);
for (std::size_t k = 0; k < NumPsqtRegs; ++k)
vec_store_psqt(&accTilePsqt[k], psqt[k]);
}
+ }
- #else
- std::memcpy(accumulator.accumulation[Perspective], biases,
+#else
+ for (IndexType i = 0; states_to_update[i]; ++i)
+ {
+ std::memcpy(states_to_update[i]->accumulator.accumulation[Perspective],
+ st->accumulator.accumulation[Perspective],
HalfDimensions * sizeof(BiasType));
for (std::size_t k = 0; k < PSQTBuckets; ++k)
- accumulator.psqtAccumulation[Perspective][k] = 0;
+ states_to_update[i]->accumulator.psqtAccumulation[Perspective][k] = st->accumulator.psqtAccumulation[Perspective][k];
- for (const auto index : active)
+ st = states_to_update[i];
+
+ // Difference calculation for the deactivated features
+ for (const auto index : removed[i])
{
const IndexType offset = HalfDimensions * index;
for (IndexType j = 0; j < HalfDimensions; ++j)
- accumulator.accumulation[Perspective][j] += weights[offset + j];
+ st->accumulator.accumulation[Perspective][j] -= weights[offset + j];
for (std::size_t k = 0; k < PSQTBuckets; ++k)
- accumulator.psqtAccumulation[Perspective][k] += psqtWeights[index * PSQTBuckets + k];
+ st->accumulator.psqtAccumulation[Perspective][k] -= psqtWeights[index * PSQTBuckets + k];
+ }
+
+ // Difference calculation for the activated features
+ for (const auto index : added[i])
+ {
+ const IndexType offset = HalfDimensions * index;
+
+ for (IndexType j = 0; j < HalfDimensions; ++j)
+ st->accumulator.accumulation[Perspective][j] += weights[offset + j];
+
+ for (std::size_t k = 0; k < PSQTBuckets; ++k)
+ st->accumulator.psqtAccumulation[Perspective][k] += psqtWeights[index * PSQTBuckets + k];
}
- #endif
}
+#endif
+ }
- #if defined(USE_MMX)
- _mm_empty();
+ template<Color Perspective>
+ void update_accumulator_refresh(const Position& pos) const {
+ #ifdef VECTOR
+ // Gcc-10.2 unnecessarily spills AVX2 registers if this array
+ // is defined in the VECTOR code below, once in each branch
+ vec_t acc[NumRegs];
+ psqt_vec_t psqt[NumPsqtRegs];
#endif
+
+ // Refresh the accumulator
+ // Could be extracted to a separate function because it's done in 2 places,
+ // but it's unclear if compilers would correctly handle register allocation.
+ auto& accumulator = pos.state()->accumulator;
+ accumulator.computed[Perspective] = true;
+ FeatureSet::IndexList active;
+ FeatureSet::append_active_indices<Perspective>(pos, active);
+
+#ifdef VECTOR
+ for (IndexType j = 0; j < HalfDimensions / TileHeight; ++j)
+ {
+ auto biasesTile = reinterpret_cast<const vec_t*>(
+ &biases[j * TileHeight]);
+ for (IndexType k = 0; k < NumRegs; ++k)
+ acc[k] = biasesTile[k];
+
+ for (const auto index : active)
+ {
+ const IndexType offset = HalfDimensions * index + j * TileHeight;
+ auto column = reinterpret_cast<const vec_t*>(&weights[offset]);
+
+ for (unsigned k = 0; k < NumRegs; ++k)
+ acc[k] = vec_add_16(acc[k], column[k]);
+ }
+
+ auto accTile = reinterpret_cast<vec_t*>(
+ &accumulator.accumulation[Perspective][j * TileHeight]);
+ for (unsigned k = 0; k < NumRegs; k++)
+ vec_store(&accTile[k], acc[k]);
+ }
+
+ for (IndexType j = 0; j < PSQTBuckets / PsqtTileHeight; ++j)
+ {
+ for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+ psqt[k] = vec_zero_psqt();
+
+ for (const auto index : active)
+ {
+ const IndexType offset = PSQTBuckets * index + j * PsqtTileHeight;
+ auto columnPsqt = reinterpret_cast<const psqt_vec_t*>(&psqtWeights[offset]);
+
+ for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+ psqt[k] = vec_add_psqt_32(psqt[k], columnPsqt[k]);
+ }
+
+ auto accTilePsqt = reinterpret_cast<psqt_vec_t*>(
+ &accumulator.psqtAccumulation[Perspective][j * PsqtTileHeight]);
+ for (std::size_t k = 0; k < NumPsqtRegs; ++k)
+ vec_store_psqt(&accTilePsqt[k], psqt[k]);
+ }
+
+#else
+ std::memcpy(accumulator.accumulation[Perspective], biases,
+ HalfDimensions * sizeof(BiasType));
+
+ for (std::size_t k = 0; k < PSQTBuckets; ++k)
+ accumulator.psqtAccumulation[Perspective][k] = 0;
+
+ for (const auto index : active)
+ {
+ const IndexType offset = HalfDimensions * index;
+
+ for (IndexType j = 0; j < HalfDimensions; ++j)
+ accumulator.accumulation[Perspective][j] += weights[offset + j];
+
+ for (std::size_t k = 0; k < PSQTBuckets; ++k)
+ accumulator.psqtAccumulation[Perspective][k] += psqtWeights[index * PSQTBuckets + k];
+ }
+#endif
+ }
+
+ template<Color Perspective>
+ void hint_common_access_for_perspective(const Position& pos) const {
+
+ // Works like update_accumulator, but performs less work.
+ // Updates ONLY the accumulator for pos.
+
+ // Look for a usable accumulator of an earlier position. We keep track
+ // of the estimated gain in terms of features to be added/subtracted.
+ // Fast early exit.
+ if (pos.state()->accumulator.computed[Perspective])
+ return;
+
+ auto [oldest_st, _] = try_find_computed_accumulator<Perspective>(pos);
+
+ if (oldest_st->accumulator.computed[Perspective])
+ {
+ // Only update current position accumulator to minimize work.
+ StateInfo* states_to_update[2] = { pos.state(), nullptr };
+ update_accumulator_incremental<Perspective, 2>(pos, oldest_st, states_to_update);
+ }
+ else
+ {
+ update_accumulator_refresh<Perspective>(pos);
+ }
+ }
+
+ template<Color Perspective>
+ void update_accumulator(const Position& pos) const {
+
+ auto [oldest_st, next] = try_find_computed_accumulator<Perspective>(pos);
+
+ if (oldest_st->accumulator.computed[Perspective])
+ {
+ if (next == nullptr)
+ return;
+
+ // Now update the accumulators listed in states_to_update[], where the last element is a sentinel.
+ // Currently we update 2 accumulators.
+ // 1. for the current position
+ // 2. the next accumulator after the computed one
+ // The heuristic may change in the future.
+ StateInfo *states_to_update[3] =
+ { next, next == pos.state() ? nullptr : pos.state(), nullptr };
+
+ update_accumulator_incremental<Perspective, 3>(pos, oldest_st, states_to_update);
+ }
+ else
+ {
+ update_accumulator_refresh<Perspective>(pos);
+ }
}
alignas(CacheLineSize) BiasType biases[HalfDimensions];
projects / stockfish / blobdiff