Merge branch 'official-stockfish:master' into master

src/evaluate.cpp

@@ -1076,33 +1076,22 @@ Value Eval::evaluate(const Position& pos) {
 
   Value v;
 
-  if (!useNNUE)
+  // Deciding between classical and NNUE eval: for high PSQ imbalance we use classical,
-      v = Evaluation<NO_TRACE>(pos).value();
+  // but we switch to NNUE during long shuffling or with high material on the board.
+
+  if (  !useNNUE
+      || abs(eg_value(pos.psq_score())) * 5 > (850 + pos.non_pawn_material() / 64) * (5 + pos.rule50_count()))
+      v = Evaluation<NO_TRACE>(pos).value();          // classical
   else
   {
-      // Scale and shift NNUE for compatibility with search and classical evaluation
+      int scale =   883
-      auto  adjusted_NNUE = [&]()
+                  + 32 * pos.count<PAWN>()
-      {
+                  + 32 * pos.non_pawn_material() / 1024;
-         int scale =   883
-                     + 32 * pos.count<PAWN>()
-                     + 32 * pos.non_pawn_material() / 1024;
 
-         Value nnue = NNUE::evaluate(pos, true) * scale / 1024;
+       v = NNUE::evaluate(pos, true) * scale / 1024;  // NNUE
 
-         if (pos.is_chess960())
+       if (pos.is_chess960())
-             nnue += fix_FRC(pos);
+           v += fix_FRC(pos);
-
-         return nnue;
-      };
-
-      // If there is PSQ imbalance we use the classical eval, but we switch to
-      // NNUE eval faster when shuffling or if the material on the board is high.
-      int r50 = pos.rule50_count();
-      Value psq = Value(abs(eg_value(pos.psq_score())));
-      bool classical = psq * 5 > (850 + pos.non_pawn_material() / 64) * (5 + r50);
-
-      v = classical ? Evaluation<NO_TRACE>(pos).value()  // classical
-                    : adjusted_NNUE();                   // NNUE
   }
 
   // Damp down the evaluation linearly when shuffling

src/misc.cpp

@@ -77,7 +77,7 @@ namespace {
 
 /// Version number. If Version is left empty, then compile date in the format
 /// DD-MM-YY and show in engine_info.
-const string Version = "";
+const string Version = "14.1";
 
 /// Our fancy logging facility. The trick here is to replace cin.rdbuf() and
 /// cout.rdbuf() with two Tie objects that tie cin and cout to a file stream. We

src/misc.h

@@ -184,22 +184,6 @@ class RunningAverage {
       int64_t average;
 };
 
-
-template <typename T>
-class ValueListInserter {
-public:
-  ValueListInserter(T* v, std::size_t& s) :
-    values(v),
-    size(&s)
-  {
-  }
-
-  void push_back(const T& value) { values[(*size)++] = value; }
-private:
-  T* values;
-  std::size_t* size;
-};
-
 template <typename T, std::size_t MaxSize>
 class ValueList {
 
@@ -213,7 +197,6 @@ public:
   const T& operator[](std::size_t index) const { return values_[index]; }
   const T* begin() const { return values_; }
   const T* end() const { return values_ + size_; }
-  operator ValueListInserter<T>() { return ValueListInserter(values_, size_); }
 
   void swap(ValueList& other) {
     const std::size_t maxSize = std::max(size_, other.size_);

src/movepick.h

@@ -86,7 +86,7 @@ enum StatsType { NoCaptures, Captures };
 /// unsuccessful during the current search, and is used for reduction and move
 /// ordering decisions. It uses 2 tables (one for each color) indexed by
 /// the move's from and to squares, see www.chessprogramming.org/Butterfly_Boards
-typedef Stats<int16_t, 13365, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
+typedef Stats<int16_t, 14365, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
 
 /// At higher depths LowPlyHistory records successful quiet moves near the root
 /// and quiet moves which are/were in the PV (ttPv). LowPlyHistory is populated during

src/nnue/evaluate_nnue.cpp

@@ -143,6 +143,7 @@ namespace Stockfish::Eval::NNUE {
     // overaligning stack variables with alignas() doesn't work correctly.
 
     constexpr uint64_t alignment = CacheLineSize;
+    int delta = 7;
 
 #if defined(ALIGNAS_ON_STACK_VARIABLES_BROKEN)
     TransformedFeatureType transformedFeaturesUnaligned[
@@ -162,20 +163,14 @@ namespace Stockfish::Eval::NNUE {
 
     const std::size_t bucket = (pos.count<ALL_PIECES>() - 1) / 4;
     const auto psqt = featureTransformer->transform(pos, transformedFeatures, bucket);
-    const auto output = network[bucket]->propagate(transformedFeatures, buffer);
+    const auto positional = network[bucket]->propagate(transformedFeatures, buffer)[0];
 
-    int materialist = psqt;
+    // Give more value to positional evaluation when material is balanced
-    int positional  = output[0];
+    if (   adjusted
-
+        && abs(pos.non_pawn_material(WHITE) - pos.non_pawn_material(BLACK)) <= RookValueMg - BishopValueMg)
-    int delta_npm = abs(pos.non_pawn_material(WHITE) - pos.non_pawn_material(BLACK));
+      return  static_cast<Value>(((128 - delta) * psqt + (128 + delta) * positional) / 128 / OutputScale);
-    int entertainment = (adjusted && delta_npm <= RookValueMg - BishopValueMg ? 7 : 0);
+    else
-
+      return static_cast<Value>((psqt + positional) / OutputScale);
-    int A = 128 - entertainment;
-    int B = 128 + entertainment;
-
-    int sum = (A * materialist + B * positional) / 128;
-
-    return static_cast<Value>( sum / OutputScale );
   }
 
   struct NnueEvalTrace {

src/nnue/features/half_ka_v2_hm.cpp

@@ -39,7 +39,7 @@ namespace Stockfish::Eval::NNUE::Features {
   void HalfKAv2_hm::append_active_indices(
     const Position& pos,
     Color perspective,
-    ValueListInserter<IndexType> active
+    IndexList& active
   ) {
     Square ksq = pos.square<KING>(perspective);
     Bitboard bb = pos.pieces();
@@ -55,22 +55,20 @@ namespace Stockfish::Eval::NNUE::Features {
 
   void HalfKAv2_hm::append_changed_indices(
     Square ksq,
-    StateInfo* st,
+    const DirtyPiece& dp,
     Color perspective,
-    ValueListInserter<IndexType> removed,
+    IndexList& removed,
-    ValueListInserter<IndexType> added
+    IndexList& added
   ) {
-    const auto& dp = st->dirtyPiece;
     for (int i = 0; i < dp.dirty_num; ++i) {
-      Piece pc = dp.piece[i];
       if (dp.from[i] != SQ_NONE)
-        removed.push_back(make_index(perspective, dp.from[i], pc, ksq));
+        removed.push_back(make_index(perspective, dp.from[i], dp.piece[i], ksq));
       if (dp.to[i] != SQ_NONE)
-        added.push_back(make_index(perspective, dp.to[i], pc, ksq));
+        added.push_back(make_index(perspective, dp.to[i], dp.piece[i], ksq));
     }
   }
 
-  int HalfKAv2_hm::update_cost(StateInfo* st) {
+  int HalfKAv2_hm::update_cost(const StateInfo* st) {
     return st->dirtyPiece.dirty_num;
   }
 
@@ -78,7 +76,7 @@ namespace Stockfish::Eval::NNUE::Features {
     return pos.count<ALL_PIECES>();
   }
 
-  bool HalfKAv2_hm::requires_refresh(StateInfo* st, Color perspective) {
+  bool HalfKAv2_hm::requires_refresh(const StateInfo* st, Color perspective) {
     return st->dirtyPiece.piece[0] == make_piece(perspective, KING);
   }
 

src/nnue/features/half_ka_v2_hm.h

@@ -50,7 +50,7 @@ namespace Stockfish::Eval::NNUE::Features {
       PS_W_QUEEN  =  8 * SQUARE_NB,
       PS_B_QUEEN  =  9 * SQUARE_NB,
       PS_KING     =  10 * SQUARE_NB,
-      PS_NB = 11 * SQUARE_NB
+      PS_NB       =  11 * SQUARE_NB
     };
 
     static constexpr IndexType PieceSquareIndex[COLOR_NB][PIECE_NB] = {
@@ -85,36 +85,38 @@ namespace Stockfish::Eval::NNUE::Features {
       -1, -1, -1, -1, 23, 22, 21, 20,
       -1, -1, -1, -1, 19, 18, 17, 16,
       -1, -1, -1, -1, 15, 14, 13, 12,
-      -1, -1, -1, -1, 11, 10, 9, 8,
+      -1, -1, -1, -1, 11, 10,  9,  8,
-      -1, -1, -1, -1, 7, 6, 5, 4,
+      -1, -1, -1, -1,  7,  6,  5,  4,
-      -1, -1, -1, -1, 3, 2, 1, 0
+      -1, -1, -1, -1,  3,  2,  1,  0
     };
 
     // Maximum number of simultaneously active features.
     static constexpr IndexType MaxActiveDimensions = 32;
+    using IndexList = ValueList<IndexType, MaxActiveDimensions>;
 
     // Get a list of indices for active features
     static void append_active_indices(
       const Position& pos,
       Color perspective,
-      ValueListInserter<IndexType> active);
+      IndexList& active);
 
     // Get a list of indices for recently changed features
     static void append_changed_indices(
       Square ksq,
-      StateInfo* st,
+      const DirtyPiece& dp,
       Color perspective,
-      ValueListInserter<IndexType> removed,
+      IndexList& removed,
-      ValueListInserter<IndexType> added);
+      IndexList& added
+    );
 
     // Returns the cost of updating one perspective, the most costly one.
     // Assumes no refresh needed.
-    static int update_cost(StateInfo* st);
+    static int update_cost(const StateInfo* st);
     static int refresh_cost(const Position& pos);
 
     // Returns whether the change stored in this StateInfo means that
     // a full accumulator refresh is required.
-    static bool requires_refresh(StateInfo* st, Color perspective);
+    static bool requires_refresh(const StateInfo* st, Color perspective);
   };
 
 }  // namespace Stockfish::Eval::NNUE::Features

src/nnue/nnue_feature_transformer.h

@@ -370,7 +370,6 @@ namespace Stockfish::Eval::NNUE {
       // That might depend on the feature set and generally relies on the
       // feature set's update cost calculation to be correct and never
       // allow updates with more added/removed features than MaxActiveDimensions.
-      using IndexList = ValueList<IndexType, FeatureSet::MaxActiveDimensions>;
 
   #ifdef VECTOR
       // Gcc-10.2 unnecessarily spills AVX2 registers if this array
@@ -404,12 +403,12 @@ namespace Stockfish::Eval::NNUE {
 
         // Gather all features to be updated.
         const Square ksq = pos.square<KING>(perspective);
-        IndexList removed[2], added[2];
+        FeatureSet::IndexList removed[2], added[2];
         FeatureSet::append_changed_indices(
-          ksq, next, perspective, removed[0], added[0]);
+          ksq, next->dirtyPiece, perspective, removed[0], added[0]);
         for (StateInfo *st2 = pos.state(); st2 != next; st2 = st2->previous)
           FeatureSet::append_changed_indices(
-            ksq, st2, perspective, removed[1], added[1]);
+            ksq, st2->dirtyPiece, perspective, removed[1], added[1]);
 
         // Mark the accumulators as computed.
         next->accumulator.computed[perspective] = true;
@@ -534,7 +533,7 @@ namespace Stockfish::Eval::NNUE {
         // Refresh the accumulator
         auto& accumulator = pos.state()->accumulator;
         accumulator.computed[perspective] = true;
-        IndexList active;
+        FeatureSet::IndexList active;
         FeatureSet::append_active_indices(pos, perspective, active);
 
   #ifdef VECTOR

src/position.cpp

@@ -1016,9 +1016,9 @@ void Position::do_null_move(StateInfo& newSt) {
   }
 
   st->key ^= Zobrist::side;
+  ++st->rule50;
   prefetch(TT.first_entry(key()));
 
-  ++st->rule50;
   st->pliesFromNull = 0;
 
   sideToMove = ~sideToMove;

src/search.cpp

@@ -331,7 +331,6 @@ void Thread::search() {
 
   multiPV = std::min(multiPV, rootMoves.size());
 
-  ttHitAverage.set(50, 100);                  // initialize the running average at 50%
   doubleExtensionAverage[WHITE].set(0, 100);  // initialize the running average at 0%
   doubleExtensionAverage[BLACK].set(0, 100);  // initialize the running average at 0%
 
@@ -588,9 +587,9 @@ namespace {
     Value bestValue, value, ttValue, eval, maxValue, probCutBeta;
     bool givesCheck, improving, didLMR, priorCapture;
     bool captureOrPromotion, doFullDepthSearch, moveCountPruning,
-         ttCapture, singularQuietLMR, noLMRExtension;
+         ttCapture, singularQuietLMR;
     Piece movedPiece;
-    int moveCount, captureCount, quietCount, bestMoveCount;
+    int moveCount, captureCount, quietCount, bestMoveCount, improvement;
 
     // Step 1. Initialize node
     ss->inCheck        = pos.checkers();
@@ -658,6 +657,7 @@ namespace {
     ttValue = ss->ttHit ? value_from_tt(tte->value(), ss->ply, pos.rule50_count()) : VALUE_NONE;
     ttMove =  rootNode ? thisThread->rootMoves[thisThread->pvIdx].pv[0]
             : ss->ttHit    ? tte->move() : MOVE_NONE;
+    ttCapture = ttMove && pos.capture_or_promotion(ttMove);
     if (!excludedMove)
         ss->ttPv = PvNode || (ss->ttHit && tte->is_pv());
 
@@ -669,13 +669,10 @@ namespace {
         && is_ok((ss-1)->currentMove))
         thisThread->lowPlyHistory[ss->ply - 1][from_to((ss-1)->currentMove)] << stat_bonus(depth - 5);
 
-    // running average of ttHit
-    thisThread->ttHitAverage.update(ss->ttHit);
-
     // At non-PV nodes we check for an early TT cutoff
     if (  !PvNode
         && ss->ttHit
-        && tte->depth() >= depth
+        && tte->depth() > depth - (thisThread->id() % 2 == 1)
         && ttValue != VALUE_NONE // Possible in case of TT access race
         && (ttValue >= beta ? (tte->bound() & BOUND_LOWER)
                             : (tte->bound() & BOUND_UPPER)))
@@ -686,7 +683,7 @@ namespace {
             if (ttValue >= beta)
             {
                 // Bonus for a quiet ttMove that fails high
-                if (!pos.capture_or_promotion(ttMove))
+                if (!ttCapture)
                     update_quiet_stats(pos, ss, ttMove, stat_bonus(depth), depth);
 
                 // Extra penalty for early quiet moves of the previous ply
@@ -694,7 +691,7 @@ namespace {
                     update_continuation_histories(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + 1));
             }
             // Penalty for a quiet ttMove that fails low
-            else if (!pos.capture_or_promotion(ttMove))
+            else if (!ttCapture)
             {
                 int penalty = -stat_bonus(depth);
                 thisThread->mainHistory[us][from_to(ttMove)] << penalty;
@@ -768,6 +765,7 @@ namespace {
         // Skip early pruning when in check
         ss->staticEval = eval = VALUE_NONE;
         improving = false;
+        improvement = 0;
         goto moves_loop;
     }
     else if (ss->ttHit)
@@ -788,15 +786,11 @@ namespace {
     }
     else
     {
-        // In case of null move search use previous static eval with a different sign
+        ss->staticEval = eval = evaluate(pos);
-        if ((ss-1)->currentMove != MOVE_NULL)
-            ss->staticEval = eval = evaluate(pos);
-        else
-            ss->staticEval = eval = -(ss-1)->staticEval;
 
         // Save static evaluation into transposition table
-        if(!excludedMove)
+        if (!excludedMove)
-        tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
+            tte->save(posKey, VALUE_NONE, ss->ttPv, BOUND_NONE, DEPTH_NONE, MOVE_NONE, eval);
     }
 
     // Use static evaluation difference to improve quiet move ordering
@@ -806,13 +800,15 @@ namespace {
         thisThread->mainHistory[~us][from_to((ss-1)->currentMove)] << bonus;
     }
 
-    // Set up improving flag that is used in various pruning heuristics
+    // Set up the improvement variable, which is the difference between the current
-    // We define position as improving if static evaluation of position is better
+    // static evaluation and the previous static evaluation at our turn (if we were
-    // Than the previous static evaluation at our turn
+    // in check at our previous move we look at the move prior to it). The improvement
-    // In case of us being in check at our previous move we look at move prior to it
+    // margin and the improving flag are used in various pruning heuristics.
-    improving =  (ss-2)->staticEval == VALUE_NONE
+    improvement =   (ss-2)->staticEval != VALUE_NONE ? ss->staticEval - (ss-2)->staticEval
-               ? ss->staticEval > (ss-4)->staticEval || (ss-4)->staticEval == VALUE_NONE
+                  : (ss-4)->staticEval != VALUE_NONE ? ss->staticEval - (ss-4)->staticEval
-               : ss->staticEval > (ss-2)->staticEval;
+                  :                                    200;
+
+    improving = improvement > 0;
 
     // Step 7. Futility pruning: child node (~50 Elo).
     // The depth condition is important for mate finding.
@@ -828,7 +824,7 @@ namespace {
         && (ss-1)->statScore < 23767
         &&  eval >= beta
         &&  eval >= ss->staticEval
-        &&  ss->staticEval >= beta - 20 * depth - 22 * improving + 168 * ss->ttPv + 177
+        &&  ss->staticEval >= beta - 20 * depth - improvement / 15 + 204
         && !excludedMove
         &&  pos.non_pawn_material(us)
         && (ss->ply >= thisThread->nmpMinPly || us != thisThread->nmpColor))
@@ -892,19 +888,16 @@ namespace {
         assert(probCutBeta < VALUE_INFINITE);
 
         MovePicker mp(pos, ttMove, probCutBeta - ss->staticEval, &captureHistory);
-        int probCutCount = 0;
         bool ttPv = ss->ttPv;
         ss->ttPv = false;
 
-        while (   (move = mp.next_move()) != MOVE_NONE
+        while ((move = mp.next_move()) != MOVE_NONE)
-               && probCutCount < 2 + 2 * cutNode)
             if (move != excludedMove && pos.legal(move))
             {
                 assert(pos.capture_or_promotion(move));
                 assert(depth >= 5);
 
                 captureOrPromotion = true;
-                probCutCount++;
 
                 ss->currentMove = move;
                 ss->continuationHistory = &thisThread->continuationHistory[ss->inCheck]
@@ -951,7 +944,6 @@ namespace {
 
 moves_loop: // When in check, search starts here
 
-    ttCapture = ttMove && pos.capture_or_promotion(ttMove);
     int rangeReduction = 0;
 
     // Step 11. A small Probcut idea, when we are in check
@@ -984,7 +976,7 @@ moves_loop: // When in check, search starts here
                                       ss->ply);
 
     value = bestValue;
-    singularQuietLMR = moveCountPruning = noLMRExtension = false;
+    singularQuietLMR = moveCountPruning = false;
 
     // Indicate PvNodes that will probably fail low if the node was searched
     // at a depth equal or greater than the current depth, and the result of this search was a fail low.
@@ -1108,10 +1100,7 @@ moves_loop: // When in check, search starts here
               if (   !PvNode
                   && value < singularBeta - 75
                   && ss->doubleExtensions <= 6)
-              {
                   extension = 2;
-                  noLMRExtension = true;
-              }
           }
 
           // Multi-cut pruning
@@ -1122,18 +1111,9 @@ moves_loop: // When in check, search starts here
           else if (singularBeta >= beta)
               return singularBeta;
 
-          // If the eval of ttMove is greater than beta we try also if there is another
+          // If the eval of ttMove is greater than beta, we reduce it (negative extension)
-          // move that pushes it over beta, if so the position also has probably multiple
-          // moves giving fail highs. We will then reduce the ttMove (negative extension).
           else if (ttValue >= beta)
-          {
+              extension = -2;
-              ss->excludedMove = move;
-              value = search<NonPV>(pos, ss, beta - 1, beta, (depth + 3) / 2, cutNode);
-              ss->excludedMove = MOVE_NONE;
-
-              if (value >= beta)
-                  extension = -2;
-          }
       }
 
       // Capture extensions for PvNodes and cutNodes
@@ -1178,10 +1158,9 @@ moves_loop: // When in check, search starts here
       // cases where we extend a son if it has good chances to be "interesting".
       if (    depth >= 3
           &&  moveCount > 1 + 2 * rootNode
-          && (  !captureOrPromotion
+          && (   !ss->ttPv
-              || (cutNode && (ss-1)->moveCount > 1)
+              || !captureOrPromotion
-              || !ss->ttPv)
+              || (cutNode && (ss-1)->moveCount > 1)))
-          && (!PvNode || ss->ply > 1 || thisThread->id() % 4 != 3))
       {
           Depth r = reduction(improving, depth, moveCount, rangeReduction > 2);
 
@@ -1190,10 +1169,6 @@ moves_loop: // When in check, search starts here
               && bestMoveCount <= 3)
               r--;
 
-          // Decrease reduction if the ttHit running average is large (~0 Elo)
-          if (thisThread->ttHitAverage.is_greater(537, 1024))
-              r--;
-
           // Decrease reduction if position is or has been on the PV
           // and node is not likely to fail low. (~3 Elo)
           if (   ss->ttPv
@@ -1232,13 +1207,11 @@ moves_loop: // When in check, search starts here
 
           // In general we want to cap the LMR depth search at newDepth. But if reductions
           // are really negative and movecount is low, we allow this move to be searched
-          // deeper than the first move (this may lead to hidden double extensions if
+          // deeper than the first move (this may lead to hidden double extensions).
-          // newDepth got its own extension before).
+          int deeper =   r >= -1             ? 0
-          int deeper =   r >= -1               ? 0
+                       : moveCount <= 5      ? 2
-                       : noLMRExtension        ? 0
+                       : PvNode && depth > 6 ? 1
-                       : moveCount <= 5        ? 1
+                       :                       0;
-                       : (depth > 6 && PvNode) ? 1
-                       :                         0;
 
           Depth d = std::clamp(newDepth - r, 1, newDepth + deeper);
 

src/thread.h

@@ -60,7 +60,6 @@ public:
   Pawns::Table pawnsTable;
   Material::Table materialTable;
   size_t pvIdx, pvLast;
-  RunningAverage ttHitAverage;
   RunningAverage doubleExtensionAverage[COLOR_NB];
   uint64_t nodesLastExplosive;
   uint64_t nodesLastNormal;