Optimize generate_piece_blocking_evasions()

[stockfish] / src / movegen.cpp

diff --git a/src/movegen.cpp b/src/movegen.cpp
index 12260e3b9dd99fd3b67bddce75dc9498bcd81499..78533a9e75acf3f8fe4421e3bb4d49db99716311 100644 (file)
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -102,11 +102,11 @@ namespace {
 
   template<>
   inline MoveStack* generate_piece_blocking_evasions<PAWN>(const Position& p, MoveStack* m, Color us,
-                                                           Bitboard np, Bitboard bs) {
+                                                           Bitboard pnd, Bitboard bs) {
     if (us == WHITE)
-        return generate_pawn_blocking_evasions<WHITE, RANK_8, Rank3BB, DELTA_N>(p, np, bs, m);
+        return generate_pawn_blocking_evasions<WHITE, RANK_8, Rank3BB, DELTA_N>(p, pnd, bs, m);
     else
-        return generate_pawn_blocking_evasions<BLACK, RANK_1, Rank6BB, DELTA_S>(p, np, bs, m);
+        return generate_pawn_blocking_evasions<BLACK, RANK_1, Rank6BB, DELTA_S>(p, pnd, bs, m);
   }
 }
 
@@ -204,7 +204,7 @@ int generate_checks(const Position& pos, MoveStack* mlist, Bitboard dc) {
 /// only legal moves.  It returns the number of generated moves. This
 /// function is very ugly, and needs cleaning up some time later.  FIXME
 
-int generate_evasions(const Position& pos, MoveStack* mlist) {
+int generate_evasions(const Position& pos, MoveStack* mlist, Bitboard pinned) {
 
   assert(pos.is_ok());
   assert(pos.is_check());
@@ -268,13 +268,10 @@ int generate_evasions(const Position& pos, MoveStack* mlist) {
 
       assert(pos.color_of_piece_on(checksq) == them);
 
-      // Find pinned pieces
-      Bitboard not_pinned = ~pos.pinned_pieces(us);
-
       // Generate captures of the checking piece
 
       // Pawn captures
-      b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & not_pinned;
+      b1 = pos.pawn_attacks(them, checksq) & pos.pawns(us) & ~pinned;
       while (b1)
       {
           from = pop_1st_bit(&b1);
@@ -291,7 +288,7 @@ int generate_evasions(const Position& pos, MoveStack* mlist) {
       // Pieces captures
       b1 = (  (pos.piece_attacks<KNIGHT>(checksq) & pos.knights(us))
             | (pos.piece_attacks<BISHOP>(checksq) & pos.bishops_and_queens(us))
-            | (pos.piece_attacks<ROOK>(checksq)   & pos.rooks_and_queens(us)) ) & not_pinned;
+            | (pos.piece_attacks<ROOK>(checksq)   & pos.rooks_and_queens(us)) ) & ~pinned;
 
       while (b1)
       {
@@ -300,7 +297,7 @@ int generate_evasions(const Position& pos, MoveStack* mlist) {
       }
 
       // Blocking check evasions are possible only if the checking piece is
-      // a slider
+      // a slider.
       if (checkers & pos.sliders())
       {
           Bitboard blockSquares = squares_between(checksq, ksq);
@@ -308,11 +305,11 @@ int generate_evasions(const Position& pos, MoveStack* mlist) {
           assert((pos.occupied_squares() & blockSquares) == EmptyBoardBB);
 
           // Pieces moves
-          mlist = generate_piece_blocking_evasions<PAWN>(pos, mlist, us, not_pinned, blockSquares);
-          mlist = generate_piece_blocking_evasions<KNIGHT>(pos, mlist, us, not_pinned, blockSquares);
-          mlist = generate_piece_blocking_evasions<BISHOP>(pos, mlist, us, not_pinned, blockSquares);
-          mlist = generate_piece_blocking_evasions<ROOK>(pos, mlist, us, not_pinned, blockSquares);
-          mlist = generate_piece_blocking_evasions<QUEEN>(pos, mlist, us, not_pinned, blockSquares);
+          mlist = generate_piece_blocking_evasions<PAWN>(pos, mlist, us, pinned, blockSquares);
+          mlist = generate_piece_blocking_evasions<KNIGHT>(pos, mlist, us, pinned, blockSquares);
+          mlist = generate_piece_blocking_evasions<BISHOP>(pos, mlist, us, pinned, blockSquares);
+          mlist = generate_piece_blocking_evasions<ROOK>(pos, mlist, us, pinned, blockSquares);
+          mlist = generate_piece_blocking_evasions<QUEEN>(pos, mlist, us, pinned, blockSquares);
     }
 
     // Finally, the ugly special case of en passant captures. An en passant
@@ -327,7 +324,7 @@ int generate_evasions(const Position& pos, MoveStack* mlist) {
 
         assert(b1 != EmptyBoardBB);
 
-        b1 &= not_pinned;
+        b1 &= ~pinned;
         while (b1)
         {
             from = pop_1st_bit(&b1);
@@ -361,15 +358,15 @@ int generate_legal_moves(const Position& pos, MoveStack* mlist) {
 
   assert(pos.is_ok());
 
+  Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
+
   if (pos.is_check())
-      return generate_evasions(pos, mlist);
+      return generate_evasions(pos, mlist, pinned);
 
   // Generate pseudo-legal moves
   int n = generate_captures(pos, mlist);
   n += generate_noncaptures(pos, mlist + n);
 
-  Bitboard pinned = pos.pinned_pieces(pos.side_to_move());
-
   // Remove illegal moves from the list
   for (int i = 0; i < n; i++)
       if (!pos.pl_move_is_legal(mlist[i].move, pinned))
@@ -589,14 +586,18 @@ namespace {
 
   template<PieceType Piece>
   MoveStack* generate_piece_blocking_evasions(const Position& pos, MoveStack* mlist, Color us,
-                                              Bitboard not_pinned, Bitboard blockSquares) {
+                                              Bitboard pinned, Bitboard blockSquares) {
+    Square from;
+    Bitboard b;
 
-    Bitboard b = pos.pieces_of_color_and_type(us, Piece) & not_pinned;
-    while (b)
+    for (int i = 0, e = pos.piece_count(us, Piece); i < e; i++)
     {
-        Square from = pop_1st_bit(&b);
-        Bitboard bb = pos.piece_attacks<Piece>(from) & blockSquares;
-        SERIALIZE_MOVES(bb);
+        from = pos.piece_list(us, Piece, i);
+        if (pinned && bit_is_set(pinned, from))
+            continue;
+
+        b = pos.piece_attacks<Piece>(from) & blockSquares;
+        SERIALIZE_MOVES(b);
     }
     return mlist;
   }
@@ -823,12 +824,12 @@ namespace {
   }
 
   template<Color Us, Rank TRANK_8, Bitboard TRank3BB, SquareDelta TDELTA_N>
-  MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard not_pinned,
+  MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard pinned,
                                              Bitboard blockSquares, MoveStack* mlist) {
     Square to;
 
     // Find non-pinned pawns
-    Bitboard b1 = pos.pawns(Us) & not_pinned;
+    Bitboard b1 = pos.pawns(Us) & ~pinned;
 
     // Single pawn pushes. We don't have to AND with empty squares here,
     // because the blocking squares will always be empty.
@@ -851,7 +852,7 @@ namespace {
 
     // Double pawn pushes
     b2 = (Us == WHITE ? b1 << 8 : b1 >> 8) & pos.empty_squares() & TRank3BB;
-    b2 = (Us == WHITE ? b2 << 8 : b2 >> 8) & blockSquares;;
+    b2 = (Us == WHITE ? b2 << 8 : b2 >> 8) & blockSquares;
     while (b2)
     {
         to = pop_1st_bit(&b2);