Remove pawn count in space() calculation #2139

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 7408a77ccf0236c02dab1608399d7311901594c5..d1a8ffd31fb4ab954ed3849bfa927d58bde5c3bf 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -18,6 +18,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include <algorithm>
 #include <cassert>
 #include <cstring>   // For std::memset
 #include <iomanip>
@@ -186,9 +187,8 @@ namespace {
     // is also calculated is ALL_PIECES.
     Bitboard attackedBy[COLOR_NB][PIECE_TYPE_NB];
 
-    // attackedBy2[color] are the squares attacked by 2 pieces of a given color,
-    // possibly via x-ray or by one pawn and one piece. Diagonal x-ray through
-    // pawn or squares attacked by 2 pawns are not explicitly added.
+    // attackedBy2[color] are the squares attacked by at least 2 units of a given
+    // color, including x-rays. But diagonal x-rays through pawns are not computed.
     Bitboard attackedBy2[COLOR_NB];
 
     // kingRing[color] are the squares adjacent to the king, plus (only for a
@@ -241,8 +241,7 @@ namespace {
     attackedBy[Us][KING] = pos.attacks_from<KING>(ksq);
     attackedBy[Us][PAWN] = pe->pawn_attacks(Us);
     attackedBy[Us][ALL_PIECES] = attackedBy[Us][KING] | attackedBy[Us][PAWN];
-    attackedBy2[Us]            = (attackedBy[Us][KING] & attackedBy[Us][PAWN])
-                                 | dblAttackByPawn;
+    attackedBy2[Us] = dblAttackByPawn | (attackedBy[Us][KING] & attackedBy[Us][PAWN]);
 
     // Init our king safety tables
     kingRing[Us] = attackedBy[Us][KING];
@@ -309,11 +308,11 @@ namespace {
             bb = OutpostRanks & ~pe->pawn_attacks_span(Them);
             if (bb & s)
                 score += Outpost * (Pt == KNIGHT ? 4 : 2)
-                                 * (1 + bool(attackedBy[Us][PAWN] & s));
+                                 * ((attackedBy[Us][PAWN] & s) ? 2 : 1);
 
             else if (bb &= b & ~pos.pieces(Us))
                 score += Outpost * (Pt == KNIGHT ? 2 : 1)
-                                 * (1 + bool(attackedBy[Us][PAWN] & bb));
+                                 * ((attackedBy[Us][PAWN] & bb) ? 2 : 1);
 
             // Knight and Bishop bonus for being right behind a pawn
             if (shift<Down>(pos.pieces(PAWN)) & s)
@@ -328,7 +327,7 @@ namespace {
                 // bishop, bigger when the center files are blocked with pawns.
                 Bitboard blocked = pos.pieces(Us, PAWN) & shift<Down>(pos.pieces());
 
-                score -= BishopPawns * pe->pawns_on_same_color_squares(Us, s)
+                score -= BishopPawns * pos.pawns_on_same_color_squares(Us, s)
                                      * (1 + popcount(blocked & CenterFiles));
 
                 // Bonus for bishop on a long diagonal which can "see" both center squares
@@ -358,8 +357,8 @@ namespace {
                 score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
 
             // Bonus for rook on an open or semi-open file
-            if (pe->semiopen_file(Us, file_of(s)))
-                score += RookOnFile[bool(pe->semiopen_file(Them, file_of(s)))];
+            if (pos.is_semiopen_file(Us, file_of(s)))
+                score += RookOnFile[bool(pos.is_semiopen_file(Them, file_of(s)))];
 
             // Penalty when trapped by the king, even more if the king cannot castle
             else if (mob <= 3)
@@ -467,12 +466,13 @@ namespace {
                  +  69 * kingAttacksCount[Them]
                  + 185 * popcount(kingRing[Us] & weak)
                  - 100 * bool(attackedBy[Us][KNIGHT] & attackedBy[Us][KING])
+                 -  35 * bool(attackedBy[Us][BISHOP] & attackedBy[Us][KING])
                  + 150 * popcount(pos.blockers_for_king(Us) | unsafeChecks)
                  - 873 * !pos.count<QUEEN>(Them)
                  -   6 * mg_value(score) / 8
                  +       mg_value(mobility[Them] - mobility[Us])
                  +   5 * kingFlankAttacks * kingFlankAttacks / 16
-                 -   15;
+                 -   7;
 
     // Transform the kingDanger units into a Score, and subtract it from the evaluation
     if (kingDanger > 100)
@@ -671,7 +671,7 @@ namespace {
 
                 bonus += make_score(k * w, k * w);
             }
-        } // rank > RANK_3
+        } // r > RANK_3
 
         // Scale down bonus for candidate passers which need more than one
         // pawn push to become passed, or have a pawn in front of them.
@@ -716,12 +716,10 @@ namespace {
     // Find all squares which are at most three squares behind some friendly pawn
     Bitboard behind = pos.pieces(Us, PAWN);
     behind |= shift<Down>(behind);
-    behind |= shift<Down>(shift<Down>(behind));
+    behind |= shift<Down+Down>(behind);
 
     int bonus = popcount(safe) + popcount(behind & safe);
-    int weight =  pos.count<ALL_PIECES>(Us)
-                - 2 * popcount(pe->semiopenFiles[WHITE] & pe->semiopenFiles[BLACK]);
-
+    int weight = pos.count<ALL_PIECES>(Us) - 1;
     Score score = make_score(bonus * weight * weight / 16, 0);
 
     if (T)
@@ -776,8 +774,7 @@ namespace {
     if (sf == SCALE_FACTOR_NORMAL)
     {
         if (   pos.opposite_bishops()
-            && pos.non_pawn_material(WHITE) == BishopValueMg
-            && pos.non_pawn_material(BLACK) == BishopValueMg)
+            && pos.non_pawn_material() == 2 * BishopValueMg)
             sf = 16 + 4 * pe->passed_count();
         else
             sf = std::min(40 + (pos.opposite_bishops() ? 2 : 7) * pos.count<PAWN>(strongSide), sf);