Simplify unstoppable pawns

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 84b9d1154bc46c439d2e5aefa1b3c7c00a1d2370..1099a6e40b57a58e85f608d79e2857dba834faa1 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -147,7 +147,7 @@ namespace {
   // ThreatenedByPawn[PieceType] contains a penalty according to which piece
   // type is attacked by an enemy pawn.
   const Score ThreatenedByPawn[] = {
-    S(0, 0), S(0, 0), S(56, 70), S(56, 70), S(76, 99), S(86, 118)
+    S(0, 0), S(0, 0), S(80, 119), S(80, 119), S(117, 199), S(127, 218)
   };
 
   // Hanging contains a bonus for each enemy hanging piece
@@ -506,7 +506,7 @@ namespace {
     // Add a bonus according if the attacking pieces are minor or major
     if (weakEnemies)
     {
-        b = weakEnemies & (ei.attackedBy[Us][PAWN] | ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
+        b = weakEnemies & (ei.attackedBy[Us][KNIGHT] | ei.attackedBy[Us][BISHOP]);
         if (b)
             score += Threat[0][type_of(pos.piece_on(lsb(b)))];
 
@@ -613,17 +613,14 @@ namespace {
 
 
   // evaluate_unstoppable_pawns() scores the most advanced among the passed and
-  // candidate pawns. In case opponent has no pieces but pawns, this is somewhat
-  // related to the possibility that pawns are unstoppable.
+  // candidate pawns. In case both players have no pieces but pawns, this is
+  // somewhat related to the possibility that pawns are unstoppable.
 
-  Score evaluate_unstoppable_pawns(const Position& pos, Color us, const EvalInfo& ei) {
+  Score evaluate_unstoppable_pawns(Color us, const EvalInfo& ei) {
 
     Bitboard b = ei.pi->passed_pawns(us) | ei.pi->candidate_pawns(us);
 
-    if (!b || pos.non_pawn_material(~us))
-        return SCORE_ZERO;
-
-    return Unstoppable * int(relative_rank(us, frontmost_sq(us, b)));
+    return b ? Unstoppable * int(relative_rank(us, frontmost_sq(us, b))) : SCORE_ZERO;
   }
 
 
@@ -716,10 +713,10 @@ namespace {
     score +=  evaluate_passed_pawns<WHITE, Trace>(pos, ei)
             - evaluate_passed_pawns<BLACK, Trace>(pos, ei);
 
-    // If one side has only a king, score for potential unstoppable pawns
-    if (!pos.non_pawn_material(WHITE) || !pos.non_pawn_material(BLACK))
-        score +=  evaluate_unstoppable_pawns(pos, WHITE, ei)
-                - evaluate_unstoppable_pawns(pos, BLACK, ei);
+    // If both sides have only pawns, score for potential unstoppable pawns
+    if (!pos.non_pawn_material(WHITE) && !pos.non_pawn_material(BLACK))
+        score +=  evaluate_unstoppable_pawns(WHITE, ei)
+                - evaluate_unstoppable_pawns(BLACK, ei);
 
     // Evaluate space for both sides, only in middlegame
     if (ei.mi->space_weight())