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Prune dangerous moves at low depth
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At very low depths prune captures,
promotions and checks if see is negative.

STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 6772 W: 1328 L: 1173 D: 4271

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 8917 W: 1270 L: 1122 D: 6525

bench: 6024713
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ajithcj authored and mcostalba committed Sep 8, 2016
1 parent e340ce2 commit 38428ad
Showing 1 changed file with 10 additions and 0 deletions.
10 changes: 10 additions & 0 deletions src/search.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -956,6 +956,16 @@ namespace {
continue;
}
}
else if ( depth < 3 * ONE_PLY
&& !inCheck
&& bestValue > VALUE_MATED_IN_MAX_PLY
&& !rootNode
&& ( captureOrPromotion
|| givesCheck
|| pos.advanced_pawn_push(move))
&& pos.see_sign(move) < VALUE_ZERO
)
continue;

// Speculative prefetch as early as possible
prefetch(TT.first_entry(pos.key_after(move)));
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