Simplify away redundant SEE pruning condition (#1363)

[stockfish] / src / endgame.cpp

diff --git a/src/endgame.cpp b/src/endgame.cpp
index b64b75cbca63e22a0f375611d9e5e4be920ea864..39db219ed85a2c26f3f61f38f5999c51e5339bee 100644 (file)
--- a/src/endgame.cpp
+++ b/src/endgame.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) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2018 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
@@ -135,8 +135,8 @@ Value Endgame<KXK>::operator()(const Position& pos) const {
   if (   pos.count<QUEEN>(strongSide)
       || pos.count<ROOK>(strongSide)
       ||(pos.count<BISHOP>(strongSide) && pos.count<KNIGHT>(strongSide))
-      ||(pos.count<BISHOP>(strongSide) > 1 && opposite_colors(pos.squares<BISHOP>(strongSide)[0],
-                                                              pos.squares<BISHOP>(strongSide)[1])))
+      || (   (pos.pieces(strongSide, BISHOP) & ~DarkSquares)
+          && (pos.pieces(strongSide, BISHOP) &  DarkSquares)))
       result = std::min(result + VALUE_KNOWN_WIN, VALUE_MATE_IN_MAX_PLY - 1);
 
   return strongSide == pos.side_to_move() ? result : -result;
@@ -524,7 +524,7 @@ ScaleFactor Endgame<KRPKB>::operator()(const Position& pos) const {
       Square bsq = pos.square<BISHOP>(weakSide);
       Square psq = pos.square<PAWN>(strongSide);
       Rank rk = relative_rank(strongSide, psq);
-      Square push = pawn_push(strongSide);
+      Direction push = pawn_push(strongSide);
 
       // If the pawn is on the 5th rank and the pawn (currently) is on
       // the same color square as the bishop then there is a chance of
@@ -598,7 +598,7 @@ ScaleFactor Endgame<KPsK>::operator()(const Position& pos) const {
 
   // If all pawns are ahead of the king, on a single rook file and
   // the king is within one file of the pawns, it's a draw.
-  if (   !(pawns & ~in_front_bb(weakSide, rank_of(ksq)))
+  if (   !(pawns & ~forward_ranks_bb(weakSide, ksq))
       && !((pawns & ~FileABB) && (pawns & ~FileHBB))
       &&  distance<File>(ksq, lsb(pawns)) <= 1)
       return SCALE_FACTOR_DRAW;
@@ -645,7 +645,7 @@ ScaleFactor Endgame<KBPKB>::operator()(const Position& pos) const {
       if (relative_rank(strongSide, pawnSq) <= RANK_5)
           return SCALE_FACTOR_DRAW;
 
-      Bitboard path = forward_bb(strongSide, pawnSq);
+      Bitboard path = forward_file_bb(strongSide, pawnSq);
 
       if (path & pos.pieces(weakSide, KING))
           return SCALE_FACTOR_DRAW;
@@ -780,7 +780,7 @@ ScaleFactor Endgame<KNPKB>::operator()(const Position& pos) const {
 
   // King needs to get close to promoting pawn to prevent knight from blocking.
   // Rules for this are very tricky, so just approximate.
-  if (forward_bb(strongSide, pawnSq) & pos.attacks_from<BISHOP>(bishopSq))
+  if (forward_file_bb(strongSide, pawnSq) & pos.attacks_from<BISHOP>(bishopSq))
       return ScaleFactor(distance(weakKingSq, pawnSq));
 
   return SCALE_FACTOR_NONE;