Extend discovered checks regardless of SEE

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 99985fde53b4f74acd5d0ac562a2f7e2b452b045..651bd95b6feff4ceecc70840ef82fb37bafbb86d 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -747,9 +747,7 @@ namespace {
     {
         if ((ss-1)->currentMove != MOVE_NULL)
         {
-            int p = (ss-1)->statScore;
-            int bonus = p > 0 ? (-p - 2500) / 512 :
-                        p < 0 ? (-p + 2500) / 512 : 0;
+            int bonus = -(ss-1)->statScore / 512;
 
             pureStaticEval = evaluate(pos);
             ss->staticEval = eval = pureStaticEval + bonus;
@@ -872,7 +870,6 @@ namespace {
         tte = TT.probe(posKey, ttHit);
         ttValue = ttHit ? value_from_tt(tte->value(), ss->ply) : VALUE_NONE;
         ttMove = ttHit ? tte->move() : MOVE_NONE;
-        pvHit = ttHit && tte->pv_hit();
     }
 
 moves_loop: // When in check, search starts from here
@@ -956,11 +953,13 @@ moves_loop: // When in check, search starts from here
           else if (cutNode && singularBeta > beta)
               return beta;
       }
-      else if (    givesCheck // Check extension (~2 Elo)
-               &&  pos.see_ge(move))
+
+      // Check extension (~2 Elo)
+      else if (    givesCheck
+               && (pos.blockers_for_king(~us) & from_sq(move) || pos.see_ge(move)))
           extension = ONE_PLY;
 
-      // Extension if castling
+      // Castling extension
       else if (type_of(move) == CASTLING)
           extension = ONE_PLY;