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prefetch in do_move()

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this allows removing Position::key_after()

STC
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 24960 W: 6556 L: 6336 D: 12068
Ptnml(0-2): 59, 2554, 7056, 2730, 81

LTC
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 115080 W: 29319 L: 29204 D: 56557
Ptnml(0-2): 51, 10736, 35864, 10825, 64

STC with 2MB hash
LLR: 3.04 (-2.94,2.94) <-1.75,0.25>
Total: 182176 W: 46998 L: 46932 D: 88246
Ptnml(0-2): 526, 19711, 50544, 19785, 522

LTC with 8MB hash
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 441180 W: 111557 L: 111746 D: 217877
Ptnml(0-2): 229, 39698, 140929, 39501, 233

closes https://github.com/official-stockfish/Stockfish/pull/5770

bench: 1379150
This commit is contained in:
Carlos Esparza
2025-01-12 23:22:01 +01:00
committed by Joost VandeVondele
parent c085670b84
commit aaafaaecf2
3 changed files with 34 additions and 48 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/position.cpp
+11 -21
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@@ -689,7 +689,12 @@ bool Position::gives_check(Move m) const {
// Makes a move, and saves all information necessary
// to a StateInfo object. The move is assumed to be legal. Pseudo-legal
// moves should be filtered out before this function is called.
void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
// If a pointer to the TT table is passed, the entry for the new position
// will be prefetched
void Position::do_move(Move m,
StateInfo& newSt,
bool givesCheck,
const TranspositionTable* tt = nullptr) {
assert(m.is_ok());
assert(&newSt != st);
@@ -887,11 +892,13 @@ void Position::do_move(Move m, StateInfo& newSt, bool givesCheck) {
st->minorPieceKey ^= Zobrist::psq[pc][from] ^ Zobrist::psq[pc][to];
}
// Set capture piece
st->capturedPiece = captured;
// Update the key with the final value
st->key = k;
if (tt)
prefetch(tt->first_entry(key()));
// Set capture piece
st->capturedPiece = captured;
// Calculate checkers bitboard (if move gives check)
st->checkersBB = givesCheck ? attackers_to(square<KING>(them)) & pieces(us) : 0;
@@ -1069,23 +1076,6 @@ void Position::undo_null_move() {
}
// Computes the new hash key after the given move. Needed
// for speculative prefetch. It doesn't recognize special moves like castling,
// en passant and promotions.
Key Position::key_after(Move m) const {
Square from = m.from_sq();
Square to = m.to_sq();
Piece pc = piece_on(from);
Piece captured = piece_on(to);
Key k = st->key ^ Zobrist::side;
k ^= Zobrist::psq[captured][to] ^ Zobrist::psq[pc][to] ^ Zobrist::psq[pc][from];
return (captured || type_of(pc) == PAWN) ? k : adjust_key50<true>(k);
}
// Tests if the SEE (Static Exchange Evaluation)
// value of move is greater or equal to the given threshold. We'll use an
// algorithm similar to alpha-beta pruning with a null window.