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Speedup_threat_by_lesser

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This patch could have been considered a non-functional speedup, but changing
the ranking of illegal moves.

Passed STC:
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 131040 W: 34247 L: 33792 D: 63001
Ptnml(0-2): 407, 15281, 33675, 15764, 393
https://tests.stockfishchess.org/tests/live_elo/68a9a75b75da51a345a5a66d

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 280146 W: 72055 L: 71242 D: 136849
Ptnml(0-2): 153, 30252, 78438, 31089, 141
https://tests.stockfishchess.org/tests/view/68a9f58475da51a345a5a6e0

closes https://github.com/official-stockfish/Stockfish/pull/6261

Bench: 2321931
This commit is contained in:
Myself
2025-08-24 19:37:58 +02:00
committed by Joost VandeVondele
parent d11f49b790
commit 20bc19558e
1 changed files with 7 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/movepick.cpp
+5 -5
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@@ -129,13 +129,15 @@ ExtMove* MovePicker::score(MoveList<Type>& ml) {
Color us = pos.side_to_move();
[[maybe_unused]] Bitboard threatByLesser[QUEEN + 1];
[[maybe_unused]] Bitboard threatByLesser[KING + 1];
if constexpr (Type == QUIETS)
{
threatByLesser[PAWN] = 0;
threatByLesser[KNIGHT] = threatByLesser[BISHOP] = pos.attacks_by<PAWN>(~us);
threatByLesser[ROOK] =
pos.attacks_by<KNIGHT>(~us) | pos.attacks_by<BISHOP>(~us) | threatByLesser[KNIGHT];
threatByLesser[QUEEN] = pos.attacks_by<ROOK>(~us) | threatByLesser[ROOK];
threatByLesser[KING] = pos.attacks_by<QUEEN>(~us) | threatByLesser[QUEEN];
}
ExtMove* it = cur;
@@ -170,12 +172,10 @@ ExtMove* MovePicker::score(MoveList<Type>& ml) {
// penalty for moving to a square threatened by a lesser piece
// or bonus for escaping an attack by a lesser piece.
if (KNIGHT <= pt && pt <= QUEEN)
{
static constexpr int bonus[QUEEN + 1] = {0, 0, 144, 144, 256, 517};
static constexpr int bonus[KING + 1] = {0, 0, 144, 144, 256, 517, 10000};
int v = threatByLesser[pt] & to ? -95 : 100 * bool(threatByLesser[pt] & from);
m.value += bonus[pt] * v;
}
if (ply < LOW_PLY_HISTORY_SIZE)
m.value += 8 * (*lowPlyHistory)[ply][m.from_to()] / (1 + ply);