Combination of two ideas:

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 57a5517614e67c5f9f37febb857b9d2a0b3840d5..4988dc8e67695fa9251cf23a55211e023d07032d 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -531,7 +531,7 @@ namespace {
     Depth extension, newDepth, predictedDepth;
     Value bestValue, value, ttValue, eval, nullValue, futilityValue;
     bool ttHit, inCheck, givesCheck, singularExtensionNode, improving;
-    bool captureOrPromotion, dangerous, doFullDepthSearch;
+    bool captureOrPromotion, doFullDepthSearch;
     int moveCount, quietCount;
 
     // Step 1. Initialize node
@@ -847,10 +847,6 @@ moves_loop: // When in check and at SpNode search starts from here
                   ? ci.checkSquares[type_of(pos.piece_on(from_sq(move)))] & to_sq(move)
                   : pos.gives_check(move, ci);
 
-      dangerous =   givesCheck
-                 || type_of(move) != NORMAL
-                 || pos.advanced_pawn_push(move);
-
       // Step 12. Extend checks
       if (givesCheck && pos.see_sign(move) >= VALUE_ZERO)
           extension = ONE_PLY;
@@ -883,7 +879,8 @@ moves_loop: // When in check and at SpNode search starts from here
       if (   !RootNode
           && !captureOrPromotion
           && !inCheck
-          && !dangerous
+          && !givesCheck
+          && !pos.advanced_pawn_push(move)
           &&  bestValue > VALUE_MATED_IN_MAX_PLY)
       {
           // Move count based pruning
@@ -1135,6 +1132,19 @@ moves_loop: // When in check and at SpNode search starts from here
     else if (bestMove && !pos.capture_or_promotion(bestMove))
         update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount);
 
+    // Bonus for prior countermove that caused the fail low
+    else if (!bestMove)
+    {
+        if (is_ok((ss - 2)->currentMove) && is_ok((ss - 1)->currentMove) && !pos.captured_piece_type() && !inCheck && depth>=3*ONE_PLY)
+        {
+            Value bonus = Value((depth / ONE_PLY) * (depth / ONE_PLY));
+            Square prevSq = to_sq((ss - 1)->currentMove);
+            Square prevPrevSq = to_sq((ss - 2)->currentMove);
+            HistoryStats& flMoveCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
+            flMoveCmh.updateCMH(pos.piece_on(prevSq), prevSq, bonus);
+        }
+    }
+
     tte->save(posKey, value_to_tt(bestValue, ss->ply),
               bestValue >= beta ? BOUND_LOWER :
               PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
@@ -1408,21 +1418,21 @@ moves_loop: // When in check and at SpNode search starts from here
     Square prevSq = to_sq((ss-1)->currentMove);
     HistoryStats& cmh = CounterMovesHistory[pos.piece_on(prevSq)][prevSq];
 
-    History.update(pos.moved_piece(move), to_sq(move), bonus);
+    History.updateH(pos.moved_piece(move), to_sq(move), bonus);
 
     if (is_ok((ss-1)->currentMove))
     {
         Countermoves.update(pos.piece_on(prevSq), prevSq, move);
-        cmh.update(pos.moved_piece(move), to_sq(move), bonus);
+        cmh.updateCMH(pos.moved_piece(move), to_sq(move), bonus);
     }
 
     // Decrease all the other played quiet moves
     for (int i = 0; i < quietsCnt; ++i)
     {
-        History.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
+        History.updateH(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
 
         if (is_ok((ss-1)->currentMove))
-            cmh.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
+            cmh.updateCMH(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
     }
 
     // Extra penalty for PV move in previous ply when it gets refuted
@@ -1430,7 +1440,7 @@ moves_loop: // When in check and at SpNode search starts from here
     {
         Square prevPrevSq = to_sq((ss-2)->currentMove);
         HistoryStats& ttMoveCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];
-        ttMoveCmh.update(pos.piece_on(prevSq), prevSq, -bonus - 2 * depth / ONE_PLY - 1);
+        ttMoveCmh.updateCMH(pos.piece_on(prevSq), prevSq, -bonus - 2 * depth / ONE_PLY - 1);
     }
   }
 
@@ -1627,8 +1637,13 @@ void Thread::idle_loop() {
 
           assert(searching);
 
+          spinlock.acquire();
+
           searching = false;
           activePosition = nullptr;
+
+          spinlock.release();
+
           sp->slavesMask.reset(idx);
           sp->allSlavesSearching = false;
           sp->nodes += pos.nodes_searched();