Linear formula for w. Bench: 3328507 (#2239)

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index da76de100f00fcd8fb6326506f95356cb204cf86..b20c93b706296c94b1a0c8652c4e4c87cb6a95e3 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);
@@ -221,7 +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);
 
@@ -304,10 +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)
@@ -560,7 +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
@@ -621,7 +622,7 @@ namespace {
 
         if (r > RANK_3)
         {
-            int w = (r-2) * (r-2) + 2;
+            int w = 5 * r - 13;
             Square blockSq = s + Up;
 
             // Adjust bonus based on the king's proximity
@@ -654,7 +655,7 @@ namespace {
                         !(unsafeSquares & blockSq)        ?  9 :
                                                              0 ;
 
-                // Assign a larger bonus if the block square is defended.
+                // Assign a larger bonus if the block square is defended
                 if (defendedSquares & blockSq)
                     k += 5;
 
@@ -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);