From 21b0974f8d1603e695aaa8148ba7fcd28bc47704 Mon Sep 17 00:00:00 2001 From: Daniel Monroe Date: Sun, 8 Feb 2026 15:19:55 +0100 Subject: [PATCH] Simplify away main history default Passed non-regression STC LLR: 2.97 (-2.94,2.94) <-1.75,0.25> Total: 130752 W: 33725 L: 33605 D: 63422 Ptnml(0-2): 421, 15472, 33460, 15612, 411 https://tests.stockfishchess.org/tests/view/697eb9e35f56030af97b5a9e Passed non-regression LTC LLR: 2.94 (-2.94,2.94) <-1.75,0.25> Total: 53352 W: 13697 L: 13509 D: 26146 Ptnml(0-2): 36, 5804, 14811, 5986, 39 https://tests.stockfishchess.org/tests/view/6980e5846362aee5c8a55396 closes https://github.com/official-stockfish/Stockfish/pull/6590 Bench: 2375860 --- src/search.cpp | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/src/search.cpp b/src/search.cpp index 561e2a5ae..ca3a9a461 100644 --- a/src/search.cpp +++ b/src/search.cpp @@ -65,7 +65,6 @@ using namespace Search; namespace { constexpr int SEARCHEDLIST_CAPACITY = 32; -constexpr int mainHistoryDefault = 68; using SearchedList = ValueList; // (*Scalers): @@ -316,8 +315,7 @@ void Search::Worker::iterative_deepening() { for (Color c : {WHITE, BLACK}) for (int i = 0; i < UINT_16_HISTORY_SIZE; i++) - mainHistory[c][i] = - (mainHistory[c][i] - mainHistoryDefault) * 3 / 4 + mainHistoryDefault; + mainHistory[c][i] = mainHistory[c][i] * 3 / 4; // Iterative deepening loop until requested to stop or the target depth is reached while (++rootDepth < MAX_PLY && !threads.stop @@ -585,7 +583,7 @@ void Search::Worker::undo_null_move(Position& pos) { pos.undo_null_move(); } // Reset histories, usually before a new game void Search::Worker::clear() { - mainHistory.fill(mainHistoryDefault); + mainHistory.fill(0); captureHistory.fill(-689); // Each thread is responsible for clearing their part of shared history