Remove as useless micro-optimization in pawns generation (#1915)

[stockfish] / src / movegen.cpp

diff --git a/src/movegen.cpp b/src/movegen.cpp
index cb221d95e178e1833c00fb414e183561b02a9924..e7678979f42450029c78d70cb0afe0d01358139e 100644 (file)
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -2,7 +2,7 @@
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2018 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2019 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -25,34 +25,35 @@
 
 namespace {
 
-  template<CastlingRight Cr, bool Checks, bool Chess960>
-  ExtMove* generate_castling(const Position& pos, ExtMove* moveList, Color us) {
+  template<Color Us, CastlingSide Cs, bool Checks, bool Chess960>
+  ExtMove* generate_castling(const Position& pos, ExtMove* moveList) {
 
-    static const bool KingSide = (Cr == WHITE_OO || Cr == BLACK_OO);
+    constexpr CastlingRight Cr = Us | Cs;
+    constexpr bool KingSide = (Cs == KING_SIDE);
 
     if (pos.castling_impeded(Cr) || !pos.can_castle(Cr))
         return moveList;
 
     // After castling, the rook and king final positions are the same in Chess960
     // as they would be in standard chess.
-    Square kfrom = pos.square<KING>(us);
+    Square kfrom = pos.square<KING>(Us);
     Square rfrom = pos.castling_rook_square(Cr);
-    Square kto = relative_square(us, KingSide ? SQ_G1 : SQ_C1);
-    Bitboard enemies = pos.pieces(~us);
+    Square kto = relative_square(Us, KingSide ? SQ_G1 : SQ_C1);
+    Bitboard enemies = pos.pieces(~Us);
 
     assert(!pos.checkers());
 
-    const Direction K = Chess960 ? kto > kfrom ? WEST : EAST
-                                 : KingSide    ? WEST : EAST;
+    const Direction step = Chess960 ? kto > kfrom ? WEST : EAST
+                                    : KingSide    ? WEST : EAST;
 
-    for (Square s = kto; s != kfrom; s += K)
+    for (Square s = kto; s != kfrom; s += step)
         if (pos.attackers_to(s) & enemies)
             return moveList;
 
     // Because we generate only legal castling moves we need to verify that
     // when moving the castling rook we do not discover some hidden checker.
     // For instance an enemy queen in SQ_A1 when castling rook is in SQ_B1.
-    if (Chess960 && (attacks_bb<ROOK>(kto, pos.pieces() ^ rfrom) & pos.pieces(~us, ROOK, QUEEN)))
+    if (Chess960 && (attacks_bb<ROOK>(kto, pos.pieces() ^ rfrom) & pos.pieces(~Us, ROOK, QUEEN)))
         return moveList;
 
     Move m = make<CASTLING>(kfrom, rfrom);
@@ -94,13 +95,12 @@ namespace {
 
     // Compute our parametrized parameters at compile time, named according to
     // the point of view of white side.
-    const Color     Them     = (Us == WHITE ? BLACK      : WHITE);
-    const Bitboard  TRank8BB = (Us == WHITE ? Rank8BB    : Rank1BB);
-    const Bitboard  TRank7BB = (Us == WHITE ? Rank7BB    : Rank2BB);
-    const Bitboard  TRank3BB = (Us == WHITE ? Rank3BB    : Rank6BB);
-    const Direction Up       = (Us == WHITE ? NORTH      : SOUTH);
-    const Direction UpRight  = (Us == WHITE ? NORTH_EAST : SOUTH_WEST);
-    const Direction UpLeft   = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
+    constexpr Color     Them     = (Us == WHITE ? BLACK      : WHITE);
+    constexpr Bitboard  TRank7BB = (Us == WHITE ? Rank7BB    : Rank2BB);
+    constexpr Bitboard  TRank3BB = (Us == WHITE ? Rank3BB    : Rank6BB);
+    constexpr Direction Up       = (Us == WHITE ? NORTH      : SOUTH);
+    constexpr Direction UpRight  = (Us == WHITE ? NORTH_EAST : SOUTH_WEST);
+    constexpr Direction UpLeft   = (Us == WHITE ? NORTH_WEST : SOUTH_EAST);
 
     Bitboard emptySquares;
 
@@ -160,7 +160,7 @@ namespace {
     }
 
     // Promotions and underpromotions
-    if (pawnsOn7 && (Type != EVASIONS || (target & TRank8BB)))
+    if (pawnsOn7)
     {
         if (Type == CAPTURES)
             emptySquares = ~pos.pieces();
@@ -261,7 +261,7 @@ namespace {
   template<Color Us, GenType Type>
   ExtMove* generate_all(const Position& pos, ExtMove* moveList, Bitboard target) {
 
-    const bool Checks = Type == QUIET_CHECKS;
+    constexpr bool Checks = Type == QUIET_CHECKS;
 
     moveList = generate_pawn_moves<Us, Type>(pos, moveList, target);
     moveList = generate_moves<KNIGHT, Checks>(pos, moveList, Us, target);
@@ -277,17 +277,17 @@ namespace {
             *moveList++ = make_move(ksq, pop_lsb(&b));
     }
 
-    if (Type != CAPTURES && Type != EVASIONS && pos.can_castle(Us))
+    if (Type != CAPTURES && Type != EVASIONS && pos.castling_rights(Us))
     {
         if (pos.is_chess960())
         {
-            moveList = generate_castling<MakeCastling<Us,  KING_SIDE>::right, Checks, true>(pos, moveList, Us);
-            moveList = generate_castling<MakeCastling<Us, QUEEN_SIDE>::right, Checks, true>(pos, moveList, Us);
+            moveList = generate_castling<Us, KING_SIDE, Checks, true>(pos, moveList);
+            moveList = generate_castling<Us, QUEEN_SIDE, Checks, true>(pos, moveList);
         }
         else
         {
-            moveList = generate_castling<MakeCastling<Us,  KING_SIDE>::right, Checks, false>(pos, moveList, Us);
-            moveList = generate_castling<MakeCastling<Us, QUEEN_SIDE>::right, Checks, false>(pos, moveList, Us);
+            moveList = generate_castling<Us, KING_SIDE, Checks, false>(pos, moveList);
+            moveList = generate_castling<Us, QUEEN_SIDE, Checks, false>(pos, moveList);
         }
     }