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Adjust standpat return value in qsearch

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Instead of returning value itself return value between it and beta for non pv nodes - analogous to what we do after actual search there.

Passed STC:
https://tests.stockfishchess.org/tests/view/663cb1b4c0b75d7f7b98188e
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 131552 W: 34131 L: 33673 D: 63748
Ptnml(0-2): 420, 15446, 33600, 15876, 434

Passed LTC:
https://tests.stockfishchess.org/tests/view/663cda5dc0b75d7f7b981c6f
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 282798 W: 71658 L: 70833 D: 140307
Ptnml(0-2): 112, 31187, 77979, 32006, 115

closes https://github.com/official-stockfish/Stockfish/pull/5233

Bench: 1606672
This commit is contained in:
Michael Chaly
2024-05-09 21:10:24 +03:00
committed by Joost VandeVondele
parent 813c5aa532
commit d3f081ed8a
1 changed files with 2 additions and 0 deletions
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src/search.cpp
+2
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@@ -1478,6 +1478,8 @@ Value Search::Worker::qsearch(Position& pos, Stack* ss, Value alpha, Value beta,
// Stand pat. Return immediately if static value is at least beta // Stand pat. Return immediately if static value is at least beta
if (bestValue >= beta) if (bestValue >= beta)
{ {
if (std::abs(bestValue) < VALUE_TB_WIN_IN_MAX_PLY && !PvNode)
bestValue = (3 * bestValue + beta) / 4;
if (!ss->ttHit) if (!ss->ttHit)
tte->save(posKey, value_to_tt(bestValue, ss->ply), false, BOUND_LOWER, DEPTH_NONE, tte->save(posKey, value_to_tt(bestValue, ss->ply), false, BOUND_LOWER, DEPTH_NONE,
Move::none(), unadjustedStaticEval, tt.generation()); Move::none(), unadjustedStaticEval, tt.generation());