Less reduction for capture/promotions.

Exclude captures/promotions at expected cut nodes (which also not a
former PV node) from LMR if a response to the first previous
opponent move.

STC:
LLR: 2.93 (-2.94,2.94) <-0.50,2.50>
Total: 288656 W: 24886 L: 24413 D: 239357
Ptnml(0-2): 900, 19738, 102578, 20213, 899
https://tests.stockfishchess.org/tests/view/60ad505112066fd29979595b

LTC:
LLR: 2.97 (-2.94,2.94) <0.50,3.50>
Total: 31344 W: 1107 L: 975 D: 29262
Ptnml(0-2): 12, 879, 13757, 1013, 11
https://tests.stockfishchess.org/tests/view/60adffce12066fd2997959d2

closes https://github.com/official-stockfish/Stockfish/pull/3500

Bench: 3827710

diff --git a/src/search.cpp b/src/search.cpp
index c69b240836e68e129c7bfc8f4542214eaa8d4af5..9de8cc9c092bf9b82e4db12d52bafd378af2dcb4 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1121,7 +1121,7 @@ moves_loop: // When in check, search starts from here
       if (    depth >= 3
           &&  moveCount > 1 + 2 * rootNode
           && (  !captureOrPromotion
-              || cutNode
+              || (cutNode && (ss-1)->moveCount > 1)
               || (!PvNode && !formerPv))
           && (!PvNode || ss->ply > 1 || thisThread->id() % 4 != 3))
       {