Extend castling independently of singular extension

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 69488ad583fb81f1798487c5be2f6422a0db9a10..01de12a4cea99b662ce0134349be1b3c3dadaeb5 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -64,7 +64,7 @@ namespace {
   // Razor and futility margins
   constexpr int RazorMargin = 661;
   Value futility_margin(Depth d, bool improving) {
-    return Value(198 * (d / ONE_PLY) - 178 * improving);
+    return Value(198 * (d / ONE_PLY - improving));
   }
 
   // Reductions lookup table, initialized at startup
@@ -472,7 +472,10 @@ void Thread::search() {
                   ++failedHighCnt;
               }
               else
+              {
+                  ++rootMoves[pvIdx].bestMoveCount;
                   break;
+              }
 
               delta += delta / 4 + 5;
 
@@ -759,6 +762,9 @@ namespace {
         if (eval == VALUE_NONE)
             ss->staticEval = eval = evaluate(pos);
 
+        if (eval == VALUE_DRAW)
+            eval = value_draw(depth, thisThread);
+
         // Can ttValue be used as a better position evaluation?
         if (    ttValue != VALUE_NONE
             && (tte->bound() & (ttValue > eval ? BOUND_LOWER : BOUND_UPPER)))
@@ -799,7 +805,8 @@ namespace {
         && (ss-1)->currentMove != MOVE_NULL
         && (ss-1)->statScore < 22661
         &&  eval >= beta
-        &&  ss->staticEval >= beta - 33 * depth / ONE_PLY + 299
+        &&  eval >= ss->staticEval
+        &&  ss->staticEval >= beta - 33 * depth / ONE_PLY + 299 - improving * 30
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -990,10 +997,6 @@ 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
@@ -1006,6 +1009,10 @@ moves_loop: // When in check, search starts from here
                && pos.advanced_pawn_push(move)
                && 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;
@@ -1046,7 +1053,7 @@ 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;
       }
@@ -1071,10 +1078,12 @@ moves_loop: // When in check, search starts from here
       // Step 16. Reduced depth search (LMR). If the move fails high it will be
       // re-searched at full depth.
       if (    depth >= 3 * ONE_PLY
-          &&  moveCount > 1 + 3 * rootNode
+          &&  moveCount > 1 + 2 * rootNode
+          && (!rootNode || thisThread->best_move_count(move) == 0)
           && (  !captureOrPromotion
               || moveCountPruning
-              || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha))
+              || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha
+              || cutNode))
       {
           Depth r = reduction(improving, depth, moveCount);
 
@@ -1090,7 +1099,7 @@ 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)
@@ -1107,7 +1116,7 @@ moves_loop: // When in check, search starts from here
               // castling moves, because they are coded as "king captures rook" and
               // hence break make_move(). (~5 Elo)
               else if (    type_of(move) == NORMAL
-                       && !pos.see_ge(make_move(to_sq(move), from_sq(move))))
+                       && !pos.see_ge(reverse_move(move)))
                   r -= 2 * ONE_PLY;
 
               ss->statScore =  thisThread->mainHistory[us][from_to(move)]
@@ -1597,6 +1606,9 @@ moves_loop: // When in check, search starts from here
     thisThread->mainHistory[us][from_to(move)] << bonus;
     update_continuation_histories(ss, pos.moved_piece(move), to_sq(move), bonus);
 
+    if (type_of(pos.moved_piece(move)) != PAWN)
+        thisThread->mainHistory[us][from_to(reverse_move(move))] << -bonus;
+
     if (is_ok((ss-1)->currentMove))
     {
         Square prevSq = to_sq((ss-1)->currentMove);