Don't futility-prune ttMove

[stockfish] / src / position.cpp

diff --git a/src/position.cpp b/src/position.cpp
index 45d0147aef1f2c6d4b244ef8ae261ebe36bc4d7a..ca1c21c38dc8a5f2f7e9e8f16f971ed59c75313c 100644 (file)
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -658,20 +658,18 @@ inline void Position::update_checkers(Bitboard* pCheckersBB, Square ksq, Square
   const bool Rook   = (Piece == QUEEN || Piece == ROOK);
   const bool Slider = Bishop || Rook;
 
+  assert(*pCheckersBB == EmptyBoardBB);
+
   // Direct checks
-  if (  (   (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to))
+  if (  (   !Slider // try to early skip slide piece attacks
+         || (Bishop && bit_is_set(BishopPseudoAttacks[ksq], to))
          || (Rook   && bit_is_set(RookPseudoAttacks[ksq], to)))
-      && bit_is_set(attacks_from<Piece>(ksq), to)) // slow, try to early skip
-      set_bit(pCheckersBB, to);
-
-  else if (   Piece != KING
-           && !Slider
-           && bit_is_set(Piece == PAWN ? attacks_from<PAWN>(ksq, opposite_color(sideToMove))
-                                       : attacks_from<Piece>(ksq), to))
-      set_bit(pCheckersBB, to);
-
+      && bit_is_set(Piece == PAWN ? attacks_from<PAWN>(ksq, opposite_color(sideToMove)) : attacks_from<Piece>(ksq) , to))
+  {
+      *pCheckersBB = SetMaskBB[to];
+  }
   // Discovery checks
-  if (Piece != QUEEN && bit_is_set(dcCandidates, from))
+  if (Piece != QUEEN && dcCandidates && bit_is_set(dcCandidates, from))
   {
       if (Piece != ROOK)
           (*pCheckersBB) |= (attacks_from<ROOK>(ksq) & pieces(ROOK, QUEEN, side_to_move()));
@@ -691,7 +689,7 @@ void Position::do_move(Move m, StateInfo& newSt) {
   do_move(m, newSt, discovered_check_candidates(side_to_move()));
 }
 
-void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
+void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates, bool moveCanBeCheck) {
 
   assert(is_ok());
   assert(move_is_ok(m));
@@ -860,21 +858,25 @@ void Position::do_move(Move m, StateInfo& newSt, Bitboard dcCandidates) {
   st->key = key;
 
   // Update checkers bitboard, piece must be already moved
-  if (ep | pm)
-      st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us);
-  else
+  st->checkersBB = EmptyBoardBB;
+
+  if (moveCanBeCheck)
   {
-      st->checkersBB = EmptyBoardBB;
-      Square ksq = king_square(them);
-      switch (pt)
+      if (ep | pm)
+          st->checkersBB = attackers_to(king_square(them)) & pieces_of_color(us);
+      else
       {
-      case PAWN:   update_checkers<PAWN>(&(st->checkersBB), ksq, from, to, dcCandidates);   break;
-      case KNIGHT: update_checkers<KNIGHT>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
-      case BISHOP: update_checkers<BISHOP>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
-      case ROOK:   update_checkers<ROOK>(&(st->checkersBB), ksq, from, to, dcCandidates);   break;
-      case QUEEN:  update_checkers<QUEEN>(&(st->checkersBB), ksq, from, to, dcCandidates);  break;
-      case KING:   update_checkers<KING>(&(st->checkersBB), ksq, from, to, dcCandidates);   break;
-      default: assert(false); break;
+          Square ksq = king_square(them);
+          switch (pt)
+          {
+          case PAWN:   update_checkers<PAWN>(&(st->checkersBB), ksq, from, to, dcCandidates);   break;
+          case KNIGHT: update_checkers<KNIGHT>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+          case BISHOP: update_checkers<BISHOP>(&(st->checkersBB), ksq, from, to, dcCandidates); break;
+          case ROOK:   update_checkers<ROOK>(&(st->checkersBB), ksq, from, to, dcCandidates);   break;
+          case QUEEN:  update_checkers<QUEEN>(&(st->checkersBB), ksq, from, to, dcCandidates);  break;
+          case KING:   update_checkers<KING>(&(st->checkersBB), ksq, from, to, dcCandidates);   break;
+          default: assert(false); break;
+          }
       }
   }