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Use quiet ttMove in qsearch() (7962287)

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Daniel Jose reported that it was an elo gain in his engine:
http://www.talkchess.com/forum/viewtopic.php?t=54290

STC: Hash=16
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 33067 W: 6670 L: 6571 D: 19826

LTC: Hash=64
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 41181 W: 7008 L: 6920 D: 27253

And another one to verify no regression with hash pressure:

STC: Hash=4
LLR: 2.96 (-2.94,2.94) [-4.00,0.00]
Total: 25085 W: 5059 L: 4991 D: 15035

Verified that qsearch does not explode after this patch (recapture threshold).

Bench 7962287

Resolves #112
This commit is contained in:
lucasart
2014-11-10 19:14:16 +08:00
committed by Joona Kiiski
parent b777b17f6f
commit 234344500f
1 changed files with 0 additions and 7 deletions
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7
src/movepick.cpp
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@@ -103,15 +103,8 @@ MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats&
stage = QSEARCH_0;
else if (d > DEPTH_QS_RECAPTURES)
{
stage = QSEARCH_1;
// Skip TT move if is not a capture or a promotion. This avoids qsearch
// tree explosion due to a possible perpetual check or similar rare cases
// when TT table is full.
if (ttm && !pos.capture_or_promotion(ttm))
ttm = MOVE_NONE;
}
else
{
stage = RECAPTURE;