A small tweak in doEasyMove()

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 6e33bb7215d0579e035915d20c40811dac8c8ae9..2c5f130343ecc1f58bbe02a0eaaaad1928faa7eb 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -209,7 +209,6 @@ namespace {
   const int KingAttackWeights[PIECE_TYPE_NB] = { 0, 0, 78, 56, 45, 11 };
 
   // Penalties for enemy's safe checks
-  const int QueenContactCheck = 997;
   const int QueenCheck        = 745;
   const int RookCheck         = 688;
   const int BishopCheck       = 588;
@@ -293,11 +292,6 @@ namespace {
             ei.kingAdjacentZoneAttacksCount[Us] += popcount(b & ei.attackedBy[Them][KING]);
         }
 
-        if (Pt == QUEEN)
-            b &= ~(  ei.attackedBy[Them][KNIGHT]
-                   | ei.attackedBy[Them][BISHOP]
-                   | ei.attackedBy[Them][ROOK]);
-
         int mob = popcount(b & ei.mobilityArea[Us]);
 
         mobility[Us] += MobilityBonus[Pt][mob];
@@ -430,15 +424,9 @@ namespace {
                     - 717 * !pos.count<QUEEN>(Them)
                     -   7 * mg_value(score) / 5 - 5;
 
-        // Analyse the enemy's safe queen contact checks. Firstly, find the
-        // undefended squares around our king reachable by the enemy queen...
-        b = undefended & ei.attackedBy[Them][QUEEN] & ~pos.pieces(Them);
-
-        // ...and keep squares supported by another enemy piece.
-        kingDanger += QueenContactCheck * popcount(b & ei.attackedBy2[Them]);
-
         // Analyse the safe enemy's checks which are possible on next move
-        safe  = ~(ei.attackedBy[Us][ALL_PIECES] | pos.pieces(Them));
+        safe  = ~pos.pieces(Them);
+        safe &= ~ei.attackedBy[Us][ALL_PIECES] | (undefended & ei.attackedBy2[Them]);
 
         b1 = pos.attacks_from<ROOK  >(ksq);
         b2 = pos.attacks_from<BISHOP>(ksq);
@@ -606,10 +594,11 @@ namespace {
   }
 
 
-  // evaluate_passed_pawns() evaluates the passed pawns of the given color
+  // evaluate_passer_pawns() evaluates the passed pawns and candidate passed
+  // pawns of the given color.
 
   template<Color Us, bool DoTrace>
-  Score evaluate_passed_pawns(const Position& pos, const EvalInfo& ei) {
+  Score evaluate_passer_pawns(const Position& pos, const EvalInfo& ei) {
 
     const Color Them = (Us == WHITE ? BLACK : WHITE);
 
@@ -622,7 +611,6 @@ namespace {
     {
         Square s = pop_lsb(&b);
 
-        assert(pos.pawn_passed(Us, s));
         assert(!(pos.pieces(PAWN) & forward_bb(Us, s)));
 
         bb = forward_bb(Us, s) & (ei.attackedBy[Them][ALL_PIECES] | pos.pieces(Them));
@@ -683,6 +671,11 @@ namespace {
         if (!pos.non_pawn_material(Them))
             ebonus += 20;
 
+        // Scale down bonus for candidate passers which need more than one pawn
+        // push to become passed.
+        if (!pos.pawn_passed(Us, s + pawn_push(Us)))
+            mbonus /= 2, ebonus /= 2;
+
         score += make_score(mbonus, ebonus) + PassedFile[file_of(s)];
     }
 
@@ -762,8 +755,7 @@ namespace {
 
     // If we don't already have an unusual scale factor, check for certain
     // types of endgames, and use a lower scale for those.
-    if (    ei.me->game_phase() < PHASE_MIDGAME
-        && (sf == SCALE_FACTOR_NORMAL || sf == SCALE_FACTOR_ONEPAWN))
+    if (sf == SCALE_FACTOR_NORMAL || sf == SCALE_FACTOR_ONEPAWN)
     {
         if (pos.opposite_bishops())
         {
@@ -771,19 +763,18 @@ namespace {
             // is almost a draw, in case of KBP vs KB, it is even more a draw.
             if (   pos.non_pawn_material(WHITE) == BishopValueMg
                 && pos.non_pawn_material(BLACK) == BishopValueMg)
-                sf = more_than_one(pos.pieces(PAWN)) ? ScaleFactor(31) : ScaleFactor(9);
+                return more_than_one(pos.pieces(PAWN)) ? ScaleFactor(31) : ScaleFactor(9);
 
             // Endgame with opposite-colored bishops, but also other pieces. Still
             // a bit drawish, but not as drawish as with only the two bishops.
-            else
-                sf = ScaleFactor(46);
+            return ScaleFactor(46);
         }
         // Endings where weaker side can place his king in front of the opponent's
         // pawns are drawish.
         else if (    abs(eg) <= BishopValueEg
                  &&  pos.count<PAWN>(strongSide) <= 2
                  && !pos.pawn_passed(~strongSide, pos.square<KING>(~strongSide)))
-            sf = ScaleFactor(37 + 7 * pos.count<PAWN>(strongSide));
+            return ScaleFactor(37 + 7 * pos.count<PAWN>(strongSide));
     }
 
     return sf;
@@ -844,8 +835,8 @@ Value Eval::evaluate(const Position& pos) {
           - evaluate_threats<BLACK, DoTrace>(pos, ei);
 
   // Evaluate passed pawns, we need full attack information including king
-  score +=  evaluate_passed_pawns<WHITE, DoTrace>(pos, ei)
-          - evaluate_passed_pawns<BLACK, DoTrace>(pos, ei);
+  score +=  evaluate_passer_pawns<WHITE, DoTrace>(pos, ei)
+          - evaluate_passer_pawns<BLACK, DoTrace>(pos, ei);
 
   // Evaluate space for both sides, only during opening
   if (pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK) >= 12222)