Better nonpawn indexing

xu-shawn · AndyGrant · vondele · commit 889fed448c28 · 2025-01-25T20:53:53.000+01:00
Improves indexing scheme, by noting that both sides are likely to access the same non_pawn_index nearby. LLR: 2.93 (-2.94,2.94) <0.00,2.00> Total: 75936 W: 19905 L: 19554 D: 36477 Ptnml(0-2): 190, 7863, 21554, 8128, 233 https://tests.stockfishchess.org/tests/view/67904d0cfc8c306ba6cea332 closes #5816 No functional change Co-authored-by: Andrew Grant <andrew.github@grantnet.us>
diff --git a/src/history.h b/src/history.h
@@ -138,7 +138,7 @@ enum CorrHistType {
     Pawn,          // By color and pawn structure
     Major,         // By color and positions of major pieces (Queen, Rook) and King
     Minor,         // By color and positions of minor pieces (Knight, Bishop) and King
-    NonPawn,       // By color and non-pawn material positions
+    NonPawn,       // By Non-pawn material positions and color
     PieceTo,       // By [piece][to] move
     Continuation,  // Combined history of move pairs
 };
@@ -150,6 +150,11 @@ struct CorrHistTypedef {
     using type = Stats<std::int16_t, CORRECTION_HISTORY_LIMIT, COLOR_NB, CORRECTION_HISTORY_SIZE>;
 };
 
+template<>
+struct CorrHistTypedef<NonPawn> {
+    using type = Stats<std::int16_t, CORRECTION_HISTORY_LIMIT, CORRECTION_HISTORY_SIZE, COLOR_NB>;
+};
+
 template<>
 struct CorrHistTypedef<PieceTo> {
     using type = Stats<std::int16_t, CORRECTION_HISTORY_LIMIT, PIECE_NB, SQUARE_NB>;
diff --git a/src/search.cpp b/src/search.cpp
@@ -89,8 +89,8 @@ int correction_value(const Worker& w, const Position& pos, const Stack* ss) {
     const auto  pcv   = w.pawnCorrectionHistory[us][pawn_structure_index<Correction>(pos)];
     const auto  macv  = w.majorPieceCorrectionHistory[us][major_piece_index(pos)];
     const auto  micv  = w.minorPieceCorrectionHistory[us][minor_piece_index(pos)];
-    const auto  wnpcv = w.nonPawnCorrectionHistory[WHITE][us][non_pawn_index<WHITE>(pos)];
-    const auto  bnpcv = w.nonPawnCorrectionHistory[BLACK][us][non_pawn_index<BLACK>(pos)];
+    const auto  wnpcv = w.nonPawnCorrectionHistory[WHITE][non_pawn_index<WHITE>(pos)][us];
+    const auto  bnpcv = w.nonPawnCorrectionHistory[BLACK][non_pawn_index<BLACK>(pos)][us];
     const auto  cntcv =
       m.is_ok() ? (*(ss - 2)->continuationCorrectionHistory)[pos.piece_on(m.to_sq())][m.to_sq()]
                  : 0;
@@ -1442,9 +1442,9 @@ Value Search::Worker::search(
           << bonus * 114 / 128;
         thisThread->majorPieceCorrectionHistory[us][major_piece_index(pos)] << bonus * 163 / 128;
         thisThread->minorPieceCorrectionHistory[us][minor_piece_index(pos)] << bonus * 146 / 128;
-        thisThread->nonPawnCorrectionHistory[WHITE][us][non_pawn_index<WHITE>(pos)]
+        thisThread->nonPawnCorrectionHistory[WHITE][non_pawn_index<WHITE>(pos)][us]
           << bonus * nonPawnWeight / 128;
-        thisThread->nonPawnCorrectionHistory[BLACK][us][non_pawn_index<BLACK>(pos)]
+        thisThread->nonPawnCorrectionHistory[BLACK][non_pawn_index<BLACK>(pos)][us]
           << bonus * nonPawnWeight / 128;
 
         if (m.is_ok())
