Scale lazy threshold according to material. (#2170)

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 7e6260c8a34128fe588b3a2c492e07af526986b1..d211db645f383678330b3b13be842169d85daab0 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>
@@ -73,7 +74,7 @@ using namespace Trace;
 namespace {
 
   // Threshold for lazy and space evaluation
-  constexpr Value LazyThreshold  = Value(1500);
+  constexpr Value LazyThreshold  = Value(1400);
   constexpr Value SpaceThreshold = Value(12222);
 
   // KingAttackWeights[PieceType] contains king attack weights by piece type
@@ -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)
@@ -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 (pos.semiopen_file(Us, file_of(s)))
-                score += RookOnFile[bool(pos.semiopen_file(Them, file_of(s)))];
+            if (pos.is_on_semiopen_file(Us, s))
+                score += RookOnFile[bool(pos.is_on_semiopen_file(Them, s))];
 
             // Penalty when trapped by the king, even more if the king cannot castle
             else if (mob <= 3)
@@ -650,7 +649,7 @@ namespace {
                 // in the pawn's path attacked or occupied by the enemy.
                 defendedSquares = unsafeSquares = squaresToQueen = forward_file_bb(Us, s);
 
-                bb = forward_file_bb(Them, s) & pos.pieces(ROOK, QUEEN) & pos.attacks_from<ROOK>(s);
+                bb = forward_file_bb(Them, s) & pos.pieces(ROOK, QUEEN);
 
                 if (!(pos.pieces(Us) & bb))
                     defendedSquares &= attackedBy[Us][ALL_PIECES];
@@ -672,7 +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.
@@ -717,12 +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)
-               - (16 - pos.count<PAWN>()) / 4;
-
+    int weight = pos.count<ALL_PIECES>(Us) - 1;
     Score score = make_score(bonus * weight * weight / 16, 0);
 
     if (T)
@@ -777,8 +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);
@@ -817,7 +813,7 @@ namespace {
 
     // Early exit if score is high
     Value v = (mg_value(score) + eg_value(score)) / 2;
-    if (abs(v) > LazyThreshold)
+    if (abs(v) > (LazyThreshold + pos.non_pawn_material() / 64))
        return pos.side_to_move() == WHITE ? v : -v;
 
     // Main evaluation begins here