Remove SafeCheck (#946)

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 4ed5e943efe877d006a7c9158ea18db4cef35686..11ac43d5ee935ab06be0cc77130cfc48cd1763e0 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -190,14 +190,12 @@ namespace {
   const Score RookOnPawn          = S( 8, 24);
   const Score TrappedRook         = S(92,  0);
   const Score CloseEnemies        = S( 7,  0);
-  const Score SafeCheck           = S(20, 20);
   const Score OtherCheck          = S(10, 10);
   const Score ThreatByHangingPawn = S(71, 61);
   const Score LooseEnemies        = S( 0, 25);
-  const Score WeakQueen           = S(35,  0);
+  const Score WeakQueen           = S(50, 10);
   const Score Hanging             = S(48, 27);
   const Score ThreatByPawnPush    = S(38, 22);
-  const Score Unstoppable         = S( 0, 20);
   const Score PawnlessFlank       = S(20, 80);
   const Score HinderPassedPawn    = S( 7,  0);
   const Score ThreatByRank        = S(16,  3);
@@ -215,10 +213,10 @@ namespace {
 
   // Penalties for enemy's safe checks
   const int QueenContactCheck = 997;
-  const int QueenCheck        = 695;
-  const int RookCheck         = 638;
-  const int BishopCheck       = 538;
-  const int KnightCheck       = 874;
+  const int QueenCheck        = 745;
+  const int RookCheck         = 688;
+  const int BishopCheck       = 588;
+  const int KnightCheck       = 924;
 
 
   // eval_init() initializes king and attack bitboards for a given color
@@ -448,7 +446,7 @@ namespace {
 
         // Enemy queen safe checks
         if ((b1 | b2) & ei.attackedBy[Them][QUEEN] & safe)
-            kingDanger += QueenCheck, score -= SafeCheck;
+            kingDanger += QueenCheck;
 
         // For other pieces, also consider the square safe if attacked twice,
         // and only defended by a queen.
@@ -458,14 +456,14 @@ namespace {
 
         // Enemy rooks safe and other checks
         if (b1 & ei.attackedBy[Them][ROOK] & safe)
-            kingDanger += RookCheck, score -= SafeCheck;
+            kingDanger += RookCheck;
 
         else if (b1 & ei.attackedBy[Them][ROOK] & other)
             score -= OtherCheck;
 
         // Enemy bishops safe and other checks
         if (b2 & ei.attackedBy[Them][BISHOP] & safe)
-            kingDanger += BishopCheck, score -= SafeCheck;
+            kingDanger += BishopCheck;
 
         else if (b2 & ei.attackedBy[Them][BISHOP] & other)
             score -= OtherCheck;
@@ -473,7 +471,7 @@ namespace {
         // Enemy knights safe and other checks
         b = pos.attacks_from<KNIGHT>(ksq) & ei.attackedBy[Them][KNIGHT];
         if (b & safe)
-            kingDanger += KnightCheck, score -= SafeCheck;
+            kingDanger += KnightCheck;
 
         else if (b & other)
             score -= OtherCheck;
@@ -678,6 +676,10 @@ namespace {
                 mbonus += rr + r * 2, ebonus += rr + r * 2;
         } // rr != 0
 
+        // Assign a small bonus when no pieces left (unstoppable)
+        if (!pos.non_pawn_material(Us) && !pos.non_pawn_material(Them))
+            ebonus += 20;
+
         score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
     }
 
@@ -852,17 +854,6 @@ Value Eval::evaluate(const Position& pos) {
   score +=  evaluate_passed_pawns<WHITE, DoTrace>(pos, ei)
           - evaluate_passed_pawns<BLACK, DoTrace>(pos, ei);
 
-  // If both sides have only pawns, score for potential unstoppable pawns
-  if (!pos.non_pawn_material(WHITE) && !pos.non_pawn_material(BLACK))
-  {
-      Bitboard b;
-      if ((b = ei.pi->passed_pawns(WHITE)) != 0)
-          score += Unstoppable * int(relative_rank(WHITE, frontmost_sq(WHITE, b)));
-
-      if ((b = ei.pi->passed_pawns(BLACK)) != 0)
-          score -= Unstoppable * int(relative_rank(BLACK, frontmost_sq(BLACK, b)));
-  }
-
   // Evaluate space for both sides, only during opening
   if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)
       score +=  evaluate_space<WHITE>(pos, ei)