From de2bf1a186ef036a7df06b448f41b00ff62f9322 Mon Sep 17 00:00:00 2001 From: Michael Chaly Date: Sat, 13 Jul 2024 22:18:38 +0300 Subject: [PATCH] Remove quiet history pruning depth limit This patch removes lmrDepth limit for quiet moves history based pruning. Previously removal of this type of depth limits was considered bad because it was performing bad for matetrack - but with this pruning heuristic this shouldn't be that bad because it's "naturally" depth limited by history threshold and should be completely disabled at depth >= 15 or so. Also this heuristic in previous years was known to scale non-linearly - bigger lmrDepth thresholds were better at longer time controls and removing it completely probably should scale pretty well. Passed STC: https://tests.stockfishchess.org/tests/view/6692b89b4ff211be9d4eab21 LLR: 2.93 (-2.94,2.94) <-1.75,0.25> Total: 114464 W: 29675 L: 29545 D: 55244 Ptnml(0-2): 372, 12516, 31329, 12640, 375 Passed LTC: https://tests.stockfishchess.org/tests/view/6692c4554ff211be9d4eab3d LLR: 2.94 (-2.94,2.94) <-1.75,0.25> Total: 67746 W: 17182 L: 17014 D: 33550 Ptnml(0-2): 28, 6993, 19652, 7183, 17 closes https://github.com/official-stockfish/Stockfish/pull/5485 Bench: 1250388 --- src/search.cpp | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/search.cpp b/src/search.cpp index 1d709749..3c6617eb 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -1022,7 +1022,7 @@ moves_loop: // When in check, search starts here + thisThread->pawnHistory[pawn_structure_index(pos)][movedPiece][move.to_sq()]; // Continuation history based pruning (~2 Elo) - if (lmrDepth < 6 && history < -4165 * depth) + if (history < -4165 * depth) continue; history += 2 * thisThread->mainHistory[us][move.from_to()];