HCha/Stockfish
1
0
Fork 0
mirror of https://github.com/HChaZZY/Stockfish.git synced 2025-12-06 10:53:50 +08:00
Code Issues Packages Projects Releases Wiki Activity

Optimize attackers_to()

Browse Source 
https://tests.stockfishchess.org/tests/view/6782decb6ddf09c0b4b6e1b0
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 105920 W: 27571 L: 27181 D: 51168
Ptnml(0-2): 284, 10808, 30403, 11164, 301

- If we only need to know if attackers exist we can skip some
  calculations.
- Also calculating slider/magic attackers first is better because the
  double lookup is slow due to memory latency.
- I also included a couple of very minor cleanups in search that
  probably don't warrant their own PR but I can open separately if
  that's better.

closes https://github.com/official-stockfish/Stockfish/pull/5762

No functional change
This commit is contained in:
mstembera
2025-01-11 14:49:09 -08:00
committed by Disservin
parent 921361829a
commit b84c8807a3
3 changed files with 23 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
src/position.cpp
View File

@@ -493,14 +493,23 @@ void Position::update_slider_blockers(Color c) const {
// Slider attacks use the occupied bitboard to indicate occupancy.
Bitboard Position::attackers_to(Square s, Bitboard occupied) const {
return (pawn_attacks_bb(BLACK, s) & pieces(WHITE, PAWN))
| (pawn_attacks_bb(WHITE, s) & pieces(BLACK, PAWN))
| (attacks_bb<KNIGHT>(s) & pieces(KNIGHT))
| (attacks_bb<ROOK>(s, occupied) & pieces(ROOK, QUEEN))
return (attacks_bb<ROOK>(s, occupied) & pieces(ROOK, QUEEN))
| (attacks_bb<BISHOP>(s, occupied) & pieces(BISHOP, QUEEN))
| (attacks_bb<KING>(s) & pieces(KING));
| (pawn_attacks_bb(BLACK, s) & pieces(WHITE, PAWN))
| (pawn_attacks_bb(WHITE, s) & pieces(BLACK, PAWN))
| (attacks_bb<KNIGHT>(s) & pieces(KNIGHT)) | (attacks_bb<KING>(s) & pieces(KING));
}
bool Position::attackers_to_exist(Square s, Bitboard occupied, Color c) const {
return ((attacks_bb<ROOK>(s) & pieces(c, ROOK, QUEEN))
&& (attacks_bb<ROOK>(s, occupied) & pieces(c, ROOK, QUEEN)))
|| ((attacks_bb<BISHOP>(s) & pieces(c, BISHOP, QUEEN))
&& (attacks_bb<BISHOP>(s, occupied) & pieces(c, BISHOP, QUEEN)))
|| (((pawn_attacks_bb(~c, s) & pieces(PAWN)) | (attacks_bb<KNIGHT>(s) & pieces(KNIGHT))
| (attacks_bb<KING>(s) & pieces(KING)))
& pieces(c));
}
// Tests whether a pseudo-legal move is legal
bool Position::legal(Move m) const {
@@ -542,7 +551,7 @@ bool Position::legal(Move m) const {
Direction step = to > from ? WEST : EAST;
for (Square s = to; s != from; s += step)
if (attackers_to(s) & pieces(~us))
if (attackers_to_exist(s, pieces(), ~us))
return false;
// In case of Chess960, verify if the Rook blocks some checks.
@@ -553,7 +562,7 @@ bool Position::legal(Move m) const {
// If the moving piece is a king, check whether the destination square is
// attacked by the opponent.
if (type_of(piece_on(from)) == KING)
return !(attackers_to(to, pieces() ^ from) & pieces(~us));
return !(attackers_to_exist(to, pieces() ^ from, ~us));
// A non-king move is legal if and only if it is not pinned or it
// is moving along the ray towards or away from the king.
@@ -622,7 +631,7 @@ bool Position::pseudo_legal(const Move m) const {
}
// In case of king moves under check we have to remove the king so as to catch
// invalid moves like b1a1 when opposite queen is on c1.
else if (attackers_to(to, pieces() ^ from) & pieces(~us))
else if (attackers_to_exist(to, pieces() ^ from, ~us))
return false;
}
@@ -1308,7 +1317,7 @@ bool Position::pos_is_ok() const {
return true;
if (pieceCount[W_KING] != 1 || pieceCount[B_KING] != 1
|| attackers_to(square<KING>(~sideToMove)) & pieces(sideToMove))
|| attackers_to_exist(square<KING>(~sideToMove), pieces(), sideToMove))
assert(0 && "pos_is_ok: Kings");
if ((pieces(PAWN) & (Rank1BB | Rank8BB)) || pieceCount[W_PAWN] > 8 || pieceCount[B_PAWN] > 8)

1
src/position.h
View File

@@ -126,6 +126,7 @@ class Position {
// Attacks to/from a given square
Bitboard attackers_to(Square s) const;
Bitboard attackers_to(Square s, Bitboard occupied) const;
bool attackers_to_exist(Square s, Bitboard occupied, Color c) const;
void update_slider_blockers(Color c) const;
template<PieceType Pt>
Bitboard attacks_by(Color c) const;

8
src/search.cpp
View File

@@ -77,7 +77,7 @@ constexpr int futility_move_count(bool improving, Depth depth) {
return (3 + depth * depth) / (2 - improving);
}
int correction_value(const Worker& w, const Position& pos, Stack* ss) {
int correction_value(const Worker& w, const Position& pos, const Stack* ss) {
const Color us = pos.side_to_move();
const auto m = (ss - 1)->currentMove;
const auto pcv = w.pawnCorrectionHistory[us][pawn_structure_index<Correction>(pos)];
@@ -1140,7 +1140,7 @@ moves_loop: // When in check, search starts here
// Decrease reduction if position is or has been on the PV (~7 Elo)
if (ss->ttPv)
r -= 1024 + (ttData.value > alpha) * 1024 + (ttData.depth >= depth) * 1024;
r -= 1024 + ((ttData.value > alpha) + (ttData.depth >= depth)) * 1024;
// Decrease reduction for PvNodes (~0 Elo on STC, ~2 Elo on LTC)
if (PvNode)
@@ -1423,8 +1423,8 @@ moves_loop: // When in check, search starts here
&& ((bestValue < ss->staticEval && bestValue < beta) // negative correction & no fail high
|| (bestValue > ss->staticEval && bestMove))) // positive correction & no fail low
{
const auto m = (ss - 1)->currentMove;
static const int nonPawnWeight = 154;
const auto m = (ss - 1)->currentMove;
constexpr int nonPawnWeight = 154;
auto bonus = std::clamp(int(bestValue - ss->staticEval) * depth / 8,
-CORRECTION_HISTORY_LIMIT / 4, CORRECTION_HISTORY_LIMIT / 4);