Remove HistoryStats

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index a17a7506856bf82f36d5dbf47f3e55694e6fa22b..c54c1269089ed9237558f4adb18595573235b4ea 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -153,11 +153,11 @@ namespace {
     {1, 0, 0, 0, 0, 1, 1 ,1},
   };
 
+  const size_t HalfDensitySize = std::extent<decltype(HalfDensity)>::value;
+
   Value bonus(Depth depth)   { int d = depth / ONE_PLY ; return  Value(d * d + 2 * d - 2); }
   Value penalty(Depth depth) { int d = depth / ONE_PLY ; return -Value(d * d + 4 * d + 1); }
 
-  const size_t HalfDensitySize = std::extent<decltype(HalfDensity)>::value;
-
   EasyMoveManager EasyMove;
   Value DrawValue[COLOR_NB];
 
@@ -211,7 +211,6 @@ void Search::clear() {
 
   for (Thread* th : Threads)
   {
-      th->history.clear();
       th->counterMoves.clear();
       th->fromTo.clear();
       th->counterMoveHistory.clear();
@@ -312,9 +311,13 @@ void MainThread::search() {
       &&  rootMoves[0].pv[0] != MOVE_NONE)
   {
       for (Thread* th : Threads)
-          if (   th->completedDepth > bestThread->completedDepth
-              && th->rootMoves[0].score > bestThread->rootMoves[0].score)
+      {
+          Depth depthDiff = th->completedDepth - bestThread->completedDepth;
+          Value scoreDiff = th->rootMoves[0].score - bestThread->rootMoves[0].score;
+
+          if (scoreDiff > 0 && depthDiff >= 0)
               bestThread = th;
+      }
   }
 
   previousScore = bestThread->rootMoves[0].score;
@@ -597,7 +600,7 @@ namespace {
     if (!rootNode)
     {
         // Step 2. Check for aborted search and immediate draw
-        if (Signals.stop.load(std::memory_order_relaxed) || pos.is_draw() || ss->ply >= MAX_PLY)
+        if (Signals.stop.load(std::memory_order_relaxed) || pos.is_draw(ss->ply) || ss->ply >= MAX_PLY)
             return ss->ply >= MAX_PLY && !inCheck ? evaluate(pos)
                                                   : DrawValue[pos.side_to_move()];
 
@@ -638,7 +641,7 @@ namespace {
         && (ttValue >= beta ? (tte->bound() & BOUND_LOWER)
                             : (tte->bound() & BOUND_UPPER)))
     {
-        // If ttMove is quiet, update killers, history, counter move on TT hit
+        // If ttMove is quiet, update move sorting heuristics on TT hit
         if (ttValue >= beta && ttMove)
         {
             if (!pos.capture_or_promotion(ttMove))
@@ -721,7 +724,7 @@ namespace {
         &&  eval + razor_margin[depth / ONE_PLY] <= alpha)
     {
         if (depth <= ONE_PLY)
-            return qsearch<NonPV, false>(pos, ss, alpha, beta);
+            return qsearch<NonPV, false>(pos, ss, alpha, alpha+1);
 
         Value ralpha = alpha - razor_margin[depth / ONE_PLY];
         Value v = qsearch<NonPV, false>(pos, ss, ralpha, ralpha+1);
@@ -979,12 +982,11 @@ moves_loop: // When in check search starts from here
                        && !pos.see_ge(make_move(to_sq(move), from_sq(move)),  VALUE_ZERO))
                   r -= 2 * ONE_PLY;
 
-              ss->history = thisThread->history[moved_piece][to_sq(move)]
-                           +    (cmh  ? (*cmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
-                           +    (fmh  ? (*fmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
-                           +    (fmh2 ? (*fmh2)[moved_piece][to_sq(move)] : VALUE_ZERO)
-                           +    thisThread->fromTo.get(~pos.side_to_move(), move)
-                           -    8000; // Correction factor
+              ss->history =  (cmh  ? (*cmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
+                           + (fmh  ? (*fmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
+                           + (fmh2 ? (*fmh2)[moved_piece][to_sq(move)] : VALUE_ZERO)
+                           + thisThread->fromTo.get(~pos.side_to_move(), move)
+                           - 8000; // Correction factor
 
               // Decrease/increase reduction by comparing opponent's stat score
               if (ss->history > VALUE_ZERO && (ss-1)->history < VALUE_ZERO)
@@ -1074,13 +1076,6 @@ moves_loop: // When in check search starts from here
 
           if (value > alpha)
           {
-              // If there is an easy move for this position, clear it if unstable
-              if (    PvNode
-                  &&  thisThread == Threads.main()
-                  &&  EasyMove.get(pos.key())
-                  && (move != EasyMove.get(pos.key()) || moveCount > 1))
-                  EasyMove.clear();
-
               bestMove = move;
 
               if (PvNode && !rootNode) // Update pv even in fail-high case
@@ -1121,7 +1116,7 @@ moves_loop: // When in check search starts from here
     else if (bestMove)
     {
 
-        // Quiet best move: update killers, history and countermoves
+        // Quiet best move: update move sorting heuristics
         if (!pos.capture_or_promotion(bestMove))
             update_stats(pos, ss, bestMove, quietsSearched, quietCount, bonus(depth));
 
@@ -1180,7 +1175,7 @@ moves_loop: // When in check search starts from here
     ss->ply = (ss-1)->ply + 1;
 
     // Check for an instant draw or if the maximum ply has been reached
-    if (pos.is_draw() || ss->ply >= MAX_PLY)
+    if (pos.is_draw(ss->ply) || ss->ply >= MAX_PLY)
         return ss->ply >= MAX_PLY && !InCheck ? evaluate(pos)
                                               : DrawValue[pos.side_to_move()];
 
@@ -1407,8 +1402,7 @@ moves_loop: // When in check search starts from here
   }
 
 
-  // update_stats() updates killers, history, countermove and countermove plus
-  // follow-up move history when a new quiet best move is found.
+  // update_stats() updates move sorting heuristics when a new quiet best move is found
 
   void update_stats(const Position& pos, Stack* ss, Move move,
                     Move* quiets, int quietsCnt, Value bonus) {
@@ -1422,7 +1416,6 @@ moves_loop: // When in check search starts from here
     Color c = pos.side_to_move();
     Thread* thisThread = pos.this_thread();
     thisThread->fromTo.update(c, move, bonus);
-    thisThread->history.update(pos.moved_piece(move), to_sq(move), bonus);
     update_cm_stats(ss, pos.moved_piece(move), to_sq(move), bonus);
 
     if ((ss-1)->counterMoves)
@@ -1435,7 +1428,6 @@ moves_loop: // When in check search starts from here
     for (int i = 0; i < quietsCnt; ++i)
     {
         thisThread->fromTo.update(c, quiets[i], -bonus);
-        thisThread->history.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
         update_cm_stats(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
     }
   }