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Simplify HalfKAv2_hm::write_indices()

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STC: https://tests.stockfishchess.org/tests/view/6a4b4b32f97ff95f78795de9
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 196064 W: 51063 L: 51020 D: 93981
Ptnml(0-2): 367, 21491, 54292, 21496, 386

closes https://github.com/official-stockfish/Stockfish/pull/6970

No functional change
This commit is contained in:
mstembera
2026-07-16 08:28:24 +02:00
committed by Joost VandeVondele
parent 151e204cc8
commit 3e3ee33a75
2 changed files with 11 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/nnue/features/half_ka_v2_hm.cpp
+10 -14
View File
@@ -45,18 +45,16 @@ void HalfKAv2_hm::write_indices(const std::array<Piece, SQUARE_NB>& oldPieces,
const __m512i vecOldPieces = _mm512_loadu_si512(oldPieces.data());
const __m512i vecNewPieces = _mm512_loadu_si512(newPieces.data());
alignas(64) static constexpr u16 psiTable[COLOR_NB][16] = {
{PS_NONE, PS_W_PAWN, PS_W_KNIGHT, PS_W_BISHOP, PS_W_ROOK, PS_W_QUEEN, PS_KING, PS_NONE,
PS_NONE, PS_B_PAWN, PS_B_KNIGHT, PS_B_BISHOP, PS_B_ROOK, PS_B_QUEEN, PS_KING, PS_NONE},
{PS_NONE, PS_B_PAWN, PS_B_KNIGHT, PS_B_BISHOP, PS_B_ROOK, PS_B_QUEEN, PS_KING, PS_NONE,
PS_NONE, PS_W_PAWN, PS_W_KNIGHT, PS_W_BISHOP, PS_W_ROOK, PS_W_QUEEN, PS_KING, PS_NONE}};
// PieceSquareIndex and KingBuckets are multiples of 64, while s and orient
// use only the low six bits. Therefore no carry crosses bit 6, and
// (s ^ orient) + psi[pc] + bucket == s ^ (psi[pc] + bucket + orient),
// allowing the orientation to be folded into the per-piece lookup offset.
const u16 flip = 56 * perspective;
const __m512i orient = _mm512_set1_epi16((u16) OrientTBL[ksq] ^ flip);
const u16 orient = u16(OrientTBL[ksq]) ^ flip;
const __m512i psi =
_mm512_castsi256_si512(_mm256_loadu_si256((const __m256i*) psiTable[perspective]));
const __m512i psi_plus_bucket =
_mm512_add_epi16(psi, _mm512_set1_epi16((u16) KingBuckets[int(ksq) ^ flip]));
_mm512_castsi256_si512(_mm256_loadu_si256((const __m256i*) PieceSquareIndex[perspective]));
const __m512i psi_plus_offset =
_mm512_add_epi16(psi, _mm512_set1_epi16(u16(KingBuckets[int(ksq) ^ flip] + orient)));
__m512i removed_squares = _mm512_maskz_compress_epi8(removedBB, AllSquares);
__m512i added_squares = _mm512_maskz_compress_epi8(addedBB, AllSquares);
@@ -69,11 +67,9 @@ void HalfKAv2_hm::write_indices(const std::array<Piece, SQUARE_NB>& oldPieces,
added_pieces = _mm512_cvtepi8_epi16(_mm512_castsi512_si256(added_pieces));
const __m512i removed_indices =
_mm512_or_si512(_mm512_xor_si512(removed_squares, orient),
_mm512_permutexvar_epi16(removed_pieces, psi_plus_bucket));
_mm512_xor_si512(removed_squares, _mm512_permutexvar_epi16(removed_pieces, psi_plus_offset));
const __m512i added_indices =
_mm512_or_si512(_mm512_xor_si512(added_squares, orient),
_mm512_permutexvar_epi16(added_pieces, psi_plus_bucket));
_mm512_xor_si512(added_squares, _mm512_permutexvar_epi16(added_pieces, psi_plus_offset));
_mm512_storeu_si512(write_removed,
_mm512_cvtepu16_epi32(_mm512_castsi512_si256(removed_indices)));
src/nnue/features/half_ka_v2_hm.h
+1 -1
View File
@@ -48,7 +48,7 @@ class HalfKAv2_hm {
PS_NB = 11 * SQUARE_NB
};
static constexpr IndexType PieceSquareIndex[COLOR_NB][PIECE_NB] = {
alignas(64) static constexpr u16 PieceSquareIndex[COLOR_NB][PIECE_NB] = {
// Convention: W - us, B - them
// Viewed from other side, W and B are reversed
{PS_NONE, PS_W_PAWN, PS_W_KNIGHT, PS_W_BISHOP, PS_W_ROOK, PS_W_QUEEN, PS_KING, PS_NONE,