Merge pull request #2 from locutus2/pawnHistStuffPR_refactored

Pawn history refactoring
official-stockfish · Oct 27, 2023 · 3bd9722 · 3bd9722
2 parents 7c456fd + c280808
commit 3bd9722
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Showing 3 changed files with 14 additions and 39 deletions.
diff --git a/src/movepick.cpp b/src/movepick.cpp
@@ -210,7 +210,7 @@ void MovePicker::score() {
                                        : 0)
                        : 0;
 
-            m.value += pawnHistory.get(pos, pos.pawn_key(), m);
+            m.value += pawnHistory[pawn_structure(pos)][pc][to];
         }
 
         else  // Type == EVASIONS
@@ -221,7 +221,7 @@ void MovePicker::score() {
             else
                 m.value = (*mainHistory)[pos.side_to_move()][from_to(m)]
                         + (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
-                        + pawnHistory.get(pos, pos.pawn_key(), m);
+                        + pawnHistory[pawn_structure(pos)][pos.moved_piece(m)][to_sq(m)];
         }
 }
 

diff --git a/src/movepick.h b/src/movepick.h
@@ -33,6 +33,10 @@
 
 namespace Stockfish {
 
+constexpr int PAWN_HISTORY_SIZE = 512;
+
+inline int pawn_structure(const Position& pos) { return pos.pawn_key() & (PAWN_HISTORY_SIZE - 1); }
+
 // StatsEntry stores the stat table value. It is usually a number but could
 // be a move or even a nested history. We use a class instead of a naked value
 // to directly call history update operator<<() on the entry so to use stats
@@ -90,39 +94,6 @@ enum StatsType {
     Captures
 };
 
-class PawnHistory {
-    static constexpr int max_size = 512;
-    using pawn_type = Stats<int16_t, 8192, COLOR_NB, max_size, PIECE_TYPE_NB, SQUARE_NB>;
-
-   public:
-    auto& get(const Position& pos, Key pawn_key, Move m) {
-        const int pawn_index = pawn_key & (max_size - 1);
-        const int pt         = type_of(pos.moved_piece(m));
-        const int to         = to_sq(m);
-
-        assert(pawn_index >= 0 && pawn_index < max_size);
-        assert(pt >= 0 && pt < PIECE_TYPE_NB);
-        assert(to >= 0 && to < SQUARE_NB);
-        return entry[pos.side_to_move()][pawn_index][pt][to];
-    }
-
-    const auto& get(const Position& pos, Key pawn_key, Move m) const {
-        const int pawn_index = pawn_key & (max_size - 1);
-        const int pt         = type_of(pos.moved_piece(m));
-        const int to         = to_sq(m);
-
-        assert(pawn_index >= 0 && pawn_index < max_size);
-        assert(pt >= 0 && pt < PIECE_TYPE_NB);
-        assert(to >= 0 && to < SQUARE_NB);
-        return entry[pos.side_to_move()][pawn_index][pt][to];
-    }
-
-    void fill(int val) { entry.fill(val); }
-
-   private:
-    pawn_type entry;
-};
-
 // ButterflyHistory records how often quiet moves have been successful or
 // unsuccessful during the current search, and is used for reduction and move
 // ordering decisions. It uses 2 tables (one for each color) indexed by
@@ -146,6 +117,8 @@ using PieceToHistory = Stats<int16_t, 29952, PIECE_NB, SQUARE_NB>;
 // (~63 elo)
 using ContinuationHistory = Stats<PieceToHistory, NOT_USED, PIECE_NB, SQUARE_NB>;
 
+// PawnStructureHistory is addressed by the pawn structure and a move's [piece][to]
+using PawnHistory = Stats<int16_t, 8192, PAWN_HISTORY_SIZE, PIECE_NB, SQUARE_NB>;
 
 // MovePicker class is used to pick one pseudo-legal move at a time from the
 // current position. The most important method is next_move(), which returns a

diff --git a/src/search.cpp b/src/search.cpp
@@ -990,7 +990,7 @@ Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, boo
                 int history = (*contHist[0])[movedPiece][to_sq(move)]
                             + (*contHist[1])[movedPiece][to_sq(move)]
                             + (*contHist[3])[movedPiece][to_sq(move)]
-                            + thisThread->pawnHistory.get(pos, pos.pawn_key(), move);
+                            + thisThread->pawnHistory[pawn_structure(pos)][movedPiece][to_sq(move)];
 
                 // Continuation history based pruning (~2 Elo)
                 if (lmrDepth < 6 && history < -3498 * depth)
@@ -1673,13 +1673,15 @@ void update_all_stats(const Position& pos,
 
         // Increase stats for the best move in case it was a quiet move
         update_quiet_stats(pos, ss, bestMove, bestMoveBonus);
-
-        thisThread->pawnHistory.get(pos, pos.pawn_key(), bestMove) << quietMoveBonus;
+        thisThread->pawnHistory[pawn_structure(pos)][moved_piece][to_sq(bestMove)]
+          << quietMoveBonus;
 
         // Decrease stats for all non-best quiet moves
         for (int i = 0; i < quietCount; ++i)
         {
-            thisThread->pawnHistory.get(pos, pos.pawn_key(), quietsSearched[i]) << -bestMoveBonus;
+            thisThread->pawnHistory[pawn_structure(pos)][pos.moved_piece(quietsSearched[i])]
+                                   [to_sq(quietsSearched[i])]
+              << -bestMoveBonus;
             thisThread->mainHistory[us][from_to(quietsSearched[i])] << -bestMoveBonus;
             update_continuation_histories(ss, pos.moved_piece(quietsSearched[i]),
                                           to_sq(quietsSearched[i]), -bestMoveBonus);