Assorted trivial cleanups June 2019

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 0da6ba4ddfa2c4b91e4387a999181d2a949ebef5..c4e02e4ea66fd39b1948efc490d1204d680027ff 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -133,6 +133,7 @@ namespace {
   };
 
   // Assorted bonuses and penalties
+  constexpr Score AttacksOnSpaceArea = S(  4,  0);
   constexpr Score BishopPawns        = S(  3,  7);
   constexpr Score CorneredBishop     = S( 50, 50);
   constexpr Score FlankAttacks       = S(  8,  0);
@@ -141,7 +142,7 @@ namespace {
   constexpr Score KnightOnQueen      = S( 16, 12);
   constexpr Score LongDiagonalBishop = S( 45,  0);
   constexpr Score MinorBehindPawn    = S( 18,  3);
-  constexpr Score Outpost            = S( 36, 12);
+  constexpr Score Outpost            = S( 18,  6);
   constexpr Score PawnlessFlank      = S( 17, 95);
   constexpr Score RestrictedPiece    = S(  7,  7);
   constexpr Score RookOnPawn         = S( 10, 32);
@@ -190,10 +191,8 @@ namespace {
     // color, including x-rays. But diagonal x-rays through pawns are not computed.
     Bitboard attackedBy2[COLOR_NB];
 
-    // kingRing[color] are the squares adjacent to the king, plus (only for a
-    // king on its first rank) the squares two ranks in front. For instance,
-    // if black's king is on g8, kingRing[BLACK] is f8, h8, f7, g7, h7, f6, g6
-    // and h6.
+    // kingRing[color] are the squares adjacent to the king plus some other
+    // very near squares, depending on king position.
     Bitboard kingRing[COLOR_NB];
 
     // kingAttackersCount[color] is the number of pieces of the given color
@@ -223,7 +222,7 @@ namespace {
     constexpr Color     Them = (Us == WHITE ? BLACK : WHITE);
     constexpr Direction Up   = (Us == WHITE ? NORTH : SOUTH);
     constexpr Direction Down = (Us == WHITE ? SOUTH : NORTH);
-    constexpr Bitboard LowRanks = (Us == WHITE ? Rank2BB | Rank3BB: Rank7BB | Rank6BB);
+    constexpr Bitboard LowRanks = (Us == WHITE ? Rank2BB | Rank3BB : Rank7BB | Rank6BB);
 
     const Square ksq = pos.square<KING>(Us);
 
@@ -306,10 +305,10 @@ namespace {
             // Bonus if piece is on an outpost square or can reach one
             bb = OutpostRanks & attackedBy[Us][PAWN] & ~pe->pawn_attacks_span(Them);
             if (bb & s)
-                score += Outpost * (Pt == KNIGHT ? 2 : 1);
+                score += Outpost * (Pt == KNIGHT ? 4 : 2);
 
             else if (bb & b & ~pos.pieces(Us))
-                score += Outpost / (Pt == KNIGHT ? 1 : 2);
+                score += Outpost * (Pt == KNIGHT ? 2 : 1);
 
             // Knight and Bishop bonus for being right behind a pawn
             if (shift<Down>(pos.pieces(PAWN)) & s)
@@ -562,7 +561,7 @@ namespace {
     b &= ~attackedBy[Them][PAWN] & safe;
 
     // Bonus for safe pawn threats on the next move
-    b = pawn_attacks_bb<Us>(b) & pos.pieces(Them);
+    b = pawn_attacks_bb<Us>(b) & nonPawnEnemies;
     score += ThreatByPawnPush * popcount(b);
 
     // Our safe or protected pawns
@@ -637,10 +636,8 @@ namespace {
             // If the pawn is free to advance, then increase the bonus
             if (pos.empty(blockSq))
             {
-                // If there is a rook or queen attacking/defending the pawn from behind,
-                // consider all the squaresToQueen. Otherwise consider only the squares
-                // in the pawn's path attacked or occupied by the enemy.
-                defendedSquares = unsafeSquares = squaresToQueen = forward_file_bb(Us, s);
+                defendedSquares = squaresToQueen = forward_file_bb(Us, s);
+                unsafeSquares = passed_pawn_span(Us, s);
 
                 bb = forward_file_bb(Them, s) & pos.pieces(ROOK, QUEEN);
 
@@ -650,9 +647,13 @@ namespace {
                 if (!(pos.pieces(Them) & bb))
                     unsafeSquares &= attackedBy[Them][ALL_PIECES] | pos.pieces(Them);
 
-                // If there aren't any enemy attacks, assign a big bonus. Otherwise
-                // assign a smaller bonus if the block square isn't attacked.
-                int k = !unsafeSquares ? 20 : !(unsafeSquares & blockSq) ? 9 : 0;
+                // If there are no enemy attacks on passed pawn span, assign a big bonus.
+                // Otherwise assign a smaller bonus if the path to queen is not attacked
+                // and even smaller bonus if it is attacked but block square is not.
+                int k = !unsafeSquares                    ? 35 :
+                        !(unsafeSquares & squaresToQueen) ? 20 :
+                        !(unsafeSquares & blockSq)        ?  9 :
+                                                             0 ;
 
                 // Assign a larger bonus if the block square is defended.
                 if (defendedSquares & blockSq)
@@ -711,6 +712,8 @@ namespace {
     int weight = pos.count<ALL_PIECES>(Us) - 1;
     Score score = make_score(bonus * weight * weight / 16, 0);
 
+    score -= AttacksOnSpaceArea * popcount(attackedBy[Them][ALL_PIECES] & behind & safe);
+
     if (T)
         Trace::add(SPACE, Us, score);
 
@@ -802,7 +805,7 @@ namespace {
 
     // Early exit if score is high
     Value v = (mg_value(score) + eg_value(score)) / 2;
-    if (abs(v) > (LazyThreshold + pos.non_pawn_material() / 64))
+    if (abs(v) > LazyThreshold + pos.non_pawn_material() / 64)
        return pos.side_to_move() == WHITE ? v : -v;
 
     // Main evaluation begins here