Small cleanups 13

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index c7343ce8002ccd4aff7fcc41d8f9dce346efe6df..78a1f7b6eb9e038a5c24f415dd127a2ddb67c13b 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -164,6 +164,8 @@ namespace {
   uint64_t perft(Position& pos, Depth depth) {
 
     StateInfo st;
+    ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+
     uint64_t cnt, nodes = 0;
     const bool leaf = (depth == 2);
 
@@ -417,7 +419,7 @@ void Thread::search() {
           // Start with a small aspiration window and, in the case of a fail
           // high/low, re-search with a bigger window until we don't fail
           // high/low anymore.
-          int failedHighCnt = 0;
+          failedHighCnt = 0;
           while (true)
           {
               Depth adjustedDepth = std::max(1, rootDepth - failedHighCnt - searchAgainCounter);
@@ -519,10 +521,14 @@ void Thread::search() {
           }
           double bestMoveInstability = 1 + 2 * totBestMoveChanges / Threads.size();
 
-          double totalTime = rootMoves.size() == 1 ? 0 :
-                             Time.optimum() * fallingEval * reduction * bestMoveInstability;
+          double totalTime = Time.optimum() * fallingEval * reduction * bestMoveInstability;
+
+          // Cap used time in case of a single legal move for a better viewer experience in tournaments
+          // yielding correct scores and sufficiently fast moves.
+          if (rootMoves.size() == 1)
+              totalTime = std::min(500.0, totalTime);
 
-          // Stop the search if we have exceeded the totalTime, at least 1ms search
+          // Stop the search if we have exceeded the totalTime
           if (Time.elapsed() > totalTime)
           {
               // If we are allowed to ponder do not stop the search now but
@@ -565,6 +571,7 @@ namespace {
 
     constexpr bool PvNode = NT == PV;
     const bool rootNode = PvNode && ss->ply == 0;
+    const Depth maxNextDepth = rootNode ? depth : depth + 1;
 
     // Check if we have an upcoming move which draws by repetition, or
     // if the opponent had an alternative move earlier to this position.
@@ -589,6 +596,8 @@ namespace {
 
     Move pv[MAX_PLY+1], capturesSearched[32], quietsSearched[64];
     StateInfo st;
+    ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+
     TTEntry* tte;
     Key posKey;
     Move ttMove, move, excludedMove, bestMove;
@@ -1049,16 +1058,7 @@ moves_loop: // When in check, search starts from here
                   && captureHistory[movedPiece][to_sq(move)][type_of(pos.piece_on(to_sq(move)))] < 0)
                   continue;
 
-              // Futility pruning for captures
-              if (   !givesCheck
-                  && lmrDepth < 6
-                  && !(PvNode && abs(bestValue) < 2)
-                  && !ss->inCheck
-                  && ss->staticEval + 169 + 244 * lmrDepth
-                     + PieceValue[MG][type_of(pos.piece_on(to_sq(move)))] <= alpha)
-                  continue;
-
-              // See based pruning
+              // SEE based pruning
               if (!pos.see_ge(move, Value(-221) * depth)) // (~25 Elo)
                   continue;
           }
@@ -1161,7 +1161,7 @@ moves_loop: // When in check, search starts from here
           if (thisThread->ttHitAverage > 509 * TtHitAverageResolution * TtHitAverageWindow / 1024)
               r--;
 
-          // Reduction if other threads are searching this position
+          // Increase reduction if other threads are searching this position
           if (th.marked())
               r++;
 
@@ -1169,6 +1169,10 @@ moves_loop: // When in check, search starts from here
           if (ss->ttPv)
               r -= 2;
 
+          // Increase reduction at root and non-PV nodes when the best move does not change frequently
+          if ((rootNode || !PvNode) && depth > 10 && thisThread->bestMoveChanges <= 2)
+              r++;
+
           if (moveCountPruning && !formerPv)
               r++;
 
@@ -1186,6 +1190,9 @@ moves_loop: // When in check, search starts from here
               if (ttCapture)
                   r++;
 
+              // Increase reduction at root if failing high
+              r += rootNode ? thisThread->failedHighCnt * thisThread->failedHighCnt * moveCount / 512 : 0;
+
               // Increase reduction for cut nodes (~10 Elo)
               if (cutNode)
                   r += 2;
@@ -1265,7 +1272,8 @@ moves_loop: // When in check, search starts from here
           (ss+1)->pv = pv;
           (ss+1)->pv[0] = MOVE_NONE;
 
-          value = -search<PV>(pos, ss+1, -beta, -alpha, newDepth, false);
+          value = -search<PV>(pos, ss+1, -beta, -alpha,
+                              std::min(maxNextDepth, newDepth), false);
       }
 
       // Step 18. Undo move
@@ -1407,6 +1415,8 @@ moves_loop: // When in check, search starts from here
 
     Move pv[MAX_PLY+1];
     StateInfo st;
+    ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+
     TTEntry* tte;
     Key posKey;
     Move ttMove, move, bestMove;
@@ -1519,7 +1529,7 @@ moves_loop: // When in check, search starts from here
       moveCount++;
 
       // Futility pruning
-      if (   !ss->inCheck
+      if (    bestValue > VALUE_TB_LOSS_IN_MAX_PLY
           && !givesCheck
           &&  futilityBase > -VALUE_KNOWN_WIN
           && !pos.advanced_pawn_push(move))
@@ -1546,7 +1556,7 @@ moves_loop: // When in check, search starts from here
       }
 
       // Do not search moves with negative SEE values
-      if (   !ss->inCheck
+      if (    bestValue > VALUE_TB_LOSS_IN_MAX_PLY
           && !(givesCheck && pos.is_discovery_check_on_king(~pos.side_to_move(), move))
           && !pos.see_ge(move))
           continue;
@@ -1569,7 +1579,7 @@ moves_loop: // When in check, search starts from here
 
       // CounterMove based pruning
       if (  !captureOrPromotion
-          && moveCount
+          && bestValue > VALUE_TB_LOSS_IN_MAX_PLY
           && (*contHist[0])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold
           && (*contHist[1])[pos.moved_piece(move)][to_sq(move)] < CounterMovePruneThreshold)
           continue;
@@ -1604,7 +1614,11 @@ moves_loop: // When in check, search starts from here
     // All legal moves have been searched. A special case: if we're in check
     // and no legal moves were found, it is checkmate.
     if (ss->inCheck && bestValue == -VALUE_INFINITE)
+    {
+        assert(!MoveList<LEGAL>(pos).size());
+
         return mated_in(ss->ply); // Plies to mate from the root
+    }
 
     tte->save(posKey, value_to_tt(bestValue, ss->ply), pvHit,
               bestValue >= beta ? BOUND_LOWER :
@@ -1898,6 +1912,8 @@ string UCI::pv(const Position& pos, Depth depth, Value alpha, Value beta) {
 bool RootMove::extract_ponder_from_tt(Position& pos) {
 
     StateInfo st;
+    ASSERT_ALIGNED(&st, Eval::NNUE::kCacheLineSize);
+
     bool ttHit;
 
     assert(pv.size() == 1);