Remove ThreatByRank

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index f8535a5f2e2851bfe1e387cc2ac0d735d422d1f4..d34e182392843b4874a07b1b5858610a4e78a143 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -86,9 +86,8 @@ namespace {
   }
 
   // Add a small random component to draw evaluations to avoid 3fold-blindness
-  Value value_draw(Depth depth, Thread* thisThread) {
-    return depth < 4 * ONE_PLY ? VALUE_DRAW
-                               : VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1);
+  Value value_draw(Thread* thisThread) {
+    return VALUE_DRAW + Value(2 * (thisThread->nodes & 1) - 1);
   }
 
   // Skill structure is used to implement strength limit
@@ -574,7 +573,7 @@ namespace {
         && !rootNode
         && pos.has_game_cycle(ss->ply))
     {
-        alpha = value_draw(depth, pos.this_thread());
+        alpha = value_draw(pos.this_thread());
         if (alpha >= beta)
             return alpha;
     }
@@ -624,7 +623,7 @@ namespace {
             || pos.is_draw(ss->ply)
             || ss->ply >= MAX_PLY)
             return (ss->ply >= MAX_PLY && !inCheck) ? evaluate(pos)
-                                                    : value_draw(depth, pos.this_thread());
+                                                    : value_draw(pos.this_thread());
 
         // Step 3. Mate distance pruning. Even if we mate at the next move our score
         // would be at best mate_in(ss->ply+1), but if alpha is already bigger because
@@ -762,6 +761,9 @@ namespace {
         if (eval == VALUE_NONE)
             ss->staticEval = eval = evaluate(pos);
 
+        if (eval == VALUE_DRAW)
+            eval = value_draw(thisThread);
+
         // Can ttValue be used as a better position evaluation?
         if (    ttValue != VALUE_NONE
             && (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER)))
@@ -994,10 +996,6 @@ moves_loop: // When in check, search starts from here
                && (pos.is_discovery_check_on_king(~us, move) || pos.see_ge(move)))
           extension = ONE_PLY;
 
-      // Castling extension
-      else if (type_of(move) == CASTLING)
-          extension = ONE_PLY;
-
       // Shuffle extension
       else if (   PvNode
                && pos.rule50_count() > 18
@@ -1011,6 +1009,10 @@ moves_loop: // When in check, search starts from here
                && pos.pawn_passed(us, to_sq(move)))
           extension = ONE_PLY;
 
+      // Castling extension
+      if (type_of(move) == CASTLING)
+          extension = ONE_PLY;
+
       // Calculate new depth for this move
       newDepth = depth - ONE_PLY + extension;
 
@@ -1050,7 +1052,7 @@ moves_loop: // When in check, search starts from here
               if (!pos.see_ge(move, Value(-(31 - std::min(lmrDepth, 18)) * lmrDepth * lmrDepth)))
                   continue;
           }
-          else if (  (!givesCheck || !extension)
+          else if (  !(givesCheck && extension)
                    && !pos.see_ge(move, Value(-199) * (depth / ONE_PLY))) // (~20 Elo)
                   continue;
       }
@@ -1096,7 +1098,7 @@ moves_loop: // When in check, search starts from here
           if ((ss-1)->moveCount > 15)
               r -= ONE_PLY;
 
-          // Decrease reduction if move has been singularly extended
+          // Decrease reduction if ttMove has been singularly extended
           r -= singularLMR * ONE_PLY;
 
           if (!captureOrPromotion)