Fix capture pruning

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index c3c2925fcf70f5dfff640875fd1295be5d924606..6d1949de88cb1cca13ba272214a2ee32b06033d5 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1542,6 +1542,36 @@ namespace {
       // Update current move
       movesSearched[moveCount++] = ss[ply].currentMove = move;
 
+      // Futility pruning for captures
+      // FIXME: test disabling 'Futility pruning for captures'
+      // FIXME: test with 'newDepth < RazorDepth'
+      Color them = opposite_color(pos.side_to_move());
+
+      if (   !isCheck
+          && newDepth < SelectiveDepth
+          && !dangerous
+          && pos.move_is_capture(move)
+          && !pos.move_is_check(move, ci)
+          && !move_is_promotion(move)
+          && move != ttMove
+          && !move_is_ep(move)
+          && (pos.type_of_piece_on(move_to(move)) != PAWN || !pos.pawn_is_passed(them, move_to(move)))) // Do not prune passed pawn captures
+      {
+          int preFutilityValueMargin = 0;
+
+          if (newDepth >= OnePly)
+              preFutilityValueMargin = 112 * bitScanReverse32(int(newDepth) * int(newDepth) / 2);
+
+          Value futilityCaptureValue = ss[ply].eval + pos.endgame_value_of_piece_on(move_to(move)) + preFutilityValueMargin + ei.futilityMargin + 90;
+
+          if (futilityCaptureValue < beta)
+          {
+              if (futilityCaptureValue > bestValue)
+                  bestValue = futilityCaptureValue;
+              continue;
+          }
+      }
+
       // Futility pruning
       if (   !isCheck
           && !dangerous