X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fevaluate.cpp;h=0f19783a2f1fbc017511bc7a12908ab8f1d5d059;hb=eddfd46a1016c544cc0f18600677fe121f3cbbff;hp=0bf64631c9d4a8686554619b43eb813c4c94de91;hpb=cff9ff21985edcf1d15e7df6c0e0039f550706ad;p=stockfish

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 0bf64631..0f19783a 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -207,7 +207,7 @@ namespace {
     ((1ULL << SQ_A8) | (1ULL << SQ_H8))
   };
 
-  // The SpaceMask[color] contains the area of the board which is consdered 
+  // The SpaceMask[color] contains the area of the board which is considered
   // by the space evaluation. In the middle game, each side is given a bonus
   // based on how many squares inside this area are safe and available for
   // friendly minor pieces.
@@ -550,19 +550,19 @@ namespace {
             ei.kingAdjacentZoneAttacksCount[Us] += count_1s_max_15<HasPopCnt>(bb);
     }
 
-    // The squares occupied by enemy pieces will be counted two times instead
-    // of one. The shift (almost) guarantees that intersection with b is zero
-    // so when we 'or' the two bitboards togheter and count we get the correct
-    // sum of '1' in b and attacked bitboards.
-    Bitboard attacked = Us == WHITE ? ((b & pos.pieces_of_color(Them)) >> 1)
-                                    : ((b & pos.pieces_of_color(Them)) << 1);
-
     // Remove squares protected by enemy pawns or occupied by our pieces
     b &= ~(ei.attackedBy[Them][PAWN] | pos.pieces_of_color(Us));
 
+    // The squares occupied by enemy pieces (not defended by pawns) will be
+    // counted two times instead of one. The shift (almost) guarantees that
+    // intersection of the shifted value with b is zero so that after or-ing
+    // the count of 1s bits is increased by the number of affected squares.
+    b |= Us == WHITE ? ((b & pos.pieces_of_color(Them)) >> 1)
+                     : ((b & pos.pieces_of_color(Them)) << 1);
+
     // Mobility
-    int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b | attacked)
-                              : count_1s<HasPopCnt>(b | attacked));
+    int mob = (Piece != QUEEN ? count_1s_max_15<HasPopCnt>(b)
+                              : count_1s<HasPopCnt>(b));
 
     if (mob > lastIndex[Piece])
         mob = lastIndex[Piece];