Late move reduction, captures and CUT nodes

Expand of Stefan Geschwentner's original idea: we always do LMR for captures at cutnodes.

Passed STC
http://tests.stockfishchess.org/tests/view/5d5b2f8e0ebc5925cf1111b8
LLR: 2.96 (-2.94,2.94) [0.50,4.50]
Total: 36026 W: 8122 L: 7779 D: 20125

Passed LTC
http://tests.stockfishchess.org/tests/view/5d5b40c80ebc5925cf111353
LLR: 3.22 (-2.94,2.94) [0.00,3.50]
Total: 133502 W: 22508 L: 21943 D: 89051

Closes https://github.com/official-stockfish/Stockfish/pull/2273

Bench: 3494372

diff --git a/src/search.cpp b/src/search.cpp
index 69488ad583fb81f1798487c5be2f6422a0db9a10..7f421b9cd38401f4e5d4d94c9f1adff3649b348b 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1074,7 +1074,8 @@ moves_loop: // When in check, search starts from here
           &&  moveCount > 1 + 3 * rootNode
           && (  !captureOrPromotion
               || moveCountPruning
-              || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha))
+              || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
+              || cutNode))
       {
           Depth r = reduction(improving, depth, moveCount);