Extend discovered checks regardless of SEE

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 6bacb4eddb533f8a4f76189b136e48e641d4aae1..9bdb2b99bcb930e0a3cb955b8b99ac07a9d67e6b 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -93,8 +93,8 @@ namespace {
 
   // Penalties for enemy's safe checks
   constexpr int QueenSafeCheck  = 780;
-  constexpr int RookSafeCheck   = 880;
-  constexpr int BishopSafeCheck = 435;
+  constexpr int RookSafeCheck   = 1080;
+  constexpr int BishopSafeCheck = 635;
   constexpr int KnightSafeCheck = 790;
 
 #define S(mg, eg) make_score(mg, eg)
@@ -434,27 +434,42 @@ namespace {
     b1 = attacks_bb<ROOK  >(ksq, pos.pieces() ^ pos.pieces(Us, QUEEN));
     b2 = attacks_bb<BISHOP>(ksq, pos.pieces() ^ pos.pieces(Us, QUEEN));
 
-    // Enemy queen safe checks
-    if ((b1 | b2) & attackedBy[Them][QUEEN] & safe & ~attackedBy[Us][QUEEN])
-        kingDanger += QueenSafeCheck;
-
-    b1 &= attackedBy[Them][ROOK];
-    b2 &= attackedBy[Them][BISHOP];
-
     // Enemy rooks checks
-    if (b1 & safe)
+    Bitboard RookCheck =  b1
+                        & safe
+                        & attackedBy[Them][ROOK];
+
+    if (RookCheck)
         kingDanger += RookSafeCheck;
     else
-        unsafeChecks |= b1;
+        unsafeChecks |= b1 & attackedBy[Them][ROOK];
+
+    // Enemy queen safe checks: we count them only if they are from squares from
+    // which we can't give a rook check, because rook checks are more valuable.
+    Bitboard QueenCheck =  (b1 | b2)
+                         & attackedBy[Them][QUEEN]
+                         & safe
+                         & ~attackedBy[Us][QUEEN]
+                         & ~RookCheck;
 
-    // Enemy bishops checks
-    if (b2 & safe)
+    if (QueenCheck)
+        kingDanger += QueenSafeCheck;
+
+    // Enemy bishops checks: we count them only if they are from squares from
+    // which we can't give a queen check, because queen checks are more valuable.
+    Bitboard BishopCheck =  b2 
+                          & attackedBy[Them][BISHOP]
+                          & safe
+                          & ~QueenCheck;
+
+    if (BishopCheck)
         kingDanger += BishopSafeCheck;
     else
-        unsafeChecks |= b2;
+        unsafeChecks |= b2 & attackedBy[Them][BISHOP];
 
     // Enemy knights checks
     b = pos.attacks_from<KNIGHT>(ksq) & attackedBy[Them][KNIGHT];
+
     if (b & safe)
         kingDanger += KnightSafeCheck;
     else
@@ -468,7 +483,7 @@ namespace {
                  +  69 * kingAttacksCount[Them]
                  + 185 * popcount(kingRing[Us] & weak)
                  + 150 * popcount(pos.blockers_for_king(Us) | unsafeChecks)
-                 +       tropism * tropism / 4
+                 +   5 * tropism * tropism / 16
                  - 873 * !pos.count<QUEEN>(Them)
                  -   6 * mg_value(score) / 8
                  +       mg_value(mobility[Them] - mobility[Us])