Improvement attempt 4(over passed patch official-stockfish#4453), inc…

…lude Bishops/Knights Hit #0: Total 18031 Hits 335 Hit Rate (%) 1.85791 King Hit #1: Total 18031 Hits 4616 Hit Rate (%) 25.6004 Queen Hit #2: Total 18031 Hits 3916 Hit Rate (%) 21.7182 Rook Hit official-stockfish#3: Total 18031 Hits 2766 Hit Rate (%) 15.3402 Bishop Hit official-stockfish#4: Total 18031 Hits 6398 Hit Rate (%) 35.4833 Knight bench: 4868464
pb00068 · Mar 23, 2023 · da764eb · da764eb
1 parent 3b51c7c
commit da764eb
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Showing 2 changed files with 9 additions and 7 deletions.
diff --git a/src/search.cpp b/src/search.cpp
@@ -568,7 +568,6 @@ namespace {
     moveCount          = captureCount = quietCount = ss->moveCount = 0;
     bestValue          = -VALUE_INFINITE;
     maxValue           = VALUE_INFINITE;
-    ss->threatenedPieces = 0;
 
     // Check for the available remaining time
     if (thisThread == Threads.main())
@@ -990,8 +989,6 @@ namespace {
       movedPiece = pos.moved_piece(move);
       givesCheck = pos.gives_check(move);
 
-      ss->threatenedPieces |= mp.threatenedPieces;
-
       // Calculate new depth for this move
       newDepth = depth - 1;
 
@@ -1026,15 +1023,21 @@ namespace {
               // SEE based pruning (~11 Elo)
               if (!pos.see_ge(move, occupied, Value(-206) * depth))
               {
-                if (depth < 2 - capture)
+                if (depth < 3 - 2 * capture)
                     continue;
                 // don't prune move if a enemy piece (KQRB) is under attack after the exchanges
                 // exclude a priori already threatened Pieces
-                Bitboard leftEnemies = (pos.pieces(~us, QUEEN, ROOK) | pos.pieces(~us, KING, BISHOP)) & occupied & ~(ss-1)->threatenedPieces;
+                Bitboard leftEnemies = (pos.pieces(~us) ^ pos.pieces(~us, PAWN)) & occupied;
                 Bitboard attacks = 0;
                 occupied |= to_sq(move);
                 while (leftEnemies && !attacks)
-                    attacks = pos.slider_attackers_to(pop_lsb(leftEnemies), occupied) & pos.pieces(us) & occupied;
+                {
+                    Square sq = pop_lsb(leftEnemies);
+                    attacks = pos.slider_attackers_to(sq, occupied) & pos.pieces(us) & occupied;
+                    // exclude attacks which were already there before SEE-exchanges
+                    if (attacks && (sq != pos.square<KING>(~us) && (pos.slider_attackers_to(sq, pos.pieces()) & pos.pieces(us))))
+                        attacks = 0;
+                }
                 if (!attacks)
                     continue;
               }

diff --git a/src/search.h b/src/search.h
@@ -51,7 +51,6 @@ struct Stack {
   bool ttHit;
   int doubleExtensions;
   int cutoffCnt;
-  Bitboard threatenedPieces;
 };