Micro optimize generate_pawn_checks()

[stockfish] / src / movegen.cpp

diff --git a/src/movegen.cpp b/src/movegen.cpp
index be9309d127368192e299e979589f79237b5a784c..cbb71688d20a6c9eaa11475e4e9aa505ffdc2d18 100644 (file)
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -53,7 +53,7 @@ namespace {
   template<CastlingSide Side>
   MoveStack* generate_castle_moves(const Position& pos, MoveStack* mlist);
 
-  template<Color Us, Rank, Bitboard, SquareDelta>
+  template<Color Us>
   MoveStack* generate_pawn_blocking_evasions(const Position&, Bitboard, Bitboard, MoveStack*);
 
   template<Color Us>
@@ -118,10 +118,9 @@ namespace {
   template<>
   inline MoveStack* generate_piece_moves<PAWN>(const Position& p, MoveStack* m,
                                                Color us, Bitboard t, Bitboard pnd) {
-    if (us == WHITE)
-        return generate_pawn_blocking_evasions<WHITE, RANK_8, Rank3BB, DELTA_N>(p, pnd, t, m);
-    else
-        return generate_pawn_blocking_evasions<BLACK, RANK_1, Rank6BB, DELTA_S>(p, pnd, t, m);
+
+    return (us == WHITE ? generate_pawn_blocking_evasions<WHITE>(p, pnd, t, m)
+                        : generate_pawn_blocking_evasions<BLACK>(p, pnd, t, m));
   }
 }
 
@@ -757,13 +756,15 @@ namespace {
     const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
     const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
     const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
+    const SquareDelta TDELTA_S = (Us == WHITE ? DELTA_S : DELTA_N);
 
     Bitboard b1, b2, b3;
-    Bitboard empty = pos.empty_squares();
     Bitboard pawns = pos.pawns(Us);
 
     if (dc & pawns)
     {
+         Bitboard empty = pos.empty_squares();
+
         // Pawn moves which gives discovered check. This is possible only if the
         // pawn is not on the same file as the enemy king, because we don't
         // generate captures.
@@ -787,10 +788,15 @@ namespace {
     }
 
     // Direct checks. These are possible only for pawns on neighboring files
-    // of the enemy king.
+    // and in the two ranks that, after the push, are in front of the enemy king.
     b1 = pawns & neighboring_files_bb(ksq) & ~dc;
+    b2 = rank_bb(ksq + 2 * TDELTA_S) | rank_bb(ksq + 3 * TDELTA_S);
+    b1 &= b2;
+    if (!b1)
+        return mlist;
 
     // Direct checks, single pawn pushes
+    Bitboard empty = pos.empty_squares();
     b2 = move_pawns<Us, DELTA_N>(b1) & empty;
     b3 = b2 & pos.pawn_attacks(Them, ksq);
     while (b3)
@@ -850,9 +856,15 @@ namespace {
     return mlist;
   }
 
-  template<Color Us, Rank TRANK_8, Bitboard TRank3BB, SquareDelta TDELTA_N>
+  template<Color Us>
   MoveStack* generate_pawn_blocking_evasions(const Position& pos, Bitboard pinned,
                                              Bitboard blockSquares, MoveStack* mlist) {
+
+    // Calculate our parametrized parameters at compile time
+    const Bitboard TRank8BB = (Us == WHITE ? Rank8BB : Rank1BB);
+    const Bitboard TRank3BB = (Us == WHITE ? Rank3BB : Rank6BB);
+    const SquareDelta TDELTA_N = (Us == WHITE ? DELTA_N : DELTA_S);
+
     Square to;
 
     // Find non-pinned pawns and push them one square
@@ -867,7 +879,7 @@ namespace {
 
         assert(pos.piece_on(to) == EMPTY);
 
-        if (square_rank(to) == TRANK_8)
+        if (square_rank(to) == TRank8BB)
         {
             (*mlist++).move = make_promotion_move(to - TDELTA_N, to, QUEEN);
             (*mlist++).move = make_promotion_move(to - TDELTA_N, to, ROOK);