Fix bounds of FutilityMoveCounts

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 44eb4ccc39d6168e3835601e6579fb4901641828..8b483b02f5a159296d0b0b16738bf9a4476f6a83 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -57,7 +57,7 @@ namespace {
   inline Value razor_margin(Depth d) { return Value(512 + 32 * d); }
 
   // Futility lookup tables (initialized at startup) and their access functions
-  int FutilityMoveCounts[2][32]; // [improving][depth]
+  int FutilityMoveCounts[2][16]; // [improving][depth]
 
   inline Value futility_margin(Depth d) {
     return Value(200 * d);
@@ -116,28 +116,26 @@ namespace {
 
 void Search::init() {
 
-  int d;  // depth (ONE_PLY == 2)
-  int hd; // half depth (ONE_PLY == 1)
-  int mc; // moveCount
-
   // Init reductions array
-  for (hd = 1; hd < 64; ++hd) for (mc = 1; mc < 64; ++mc)
-  {
-      double    pvRed = 0.00 + log(double(hd)) * log(double(mc)) / 3.00;
-      double nonPVRed = 0.33 + log(double(hd)) * log(double(mc)) / 2.25;
+  for (int d = 1; d < 64; ++d)
+      for (int mc = 1; mc < 64; ++mc)
+      {
+          double    pvRed = 0.00 + log(double(d)) * log(double(mc)) / 3.00;
+          double nonPVRed = 0.33 + log(double(d)) * log(double(mc)) / 2.25;
 
-      Reductions[1][1][hd][mc] = int8_t(   pvRed >= 1.0 ?    pvRed + 0.5: 0);
-      Reductions[0][1][hd][mc] = int8_t(nonPVRed >= 1.0 ? nonPVRed + 0.5: 0);
+          Reductions[1][1][d][mc] = int8_t(   pvRed >= 1.0 ?    pvRed + 0.5: 0);
+          Reductions[0][1][d][mc] = int8_t(nonPVRed >= 1.0 ? nonPVRed + 0.5: 0);
 
-      Reductions[1][0][hd][mc] = Reductions[1][1][hd][mc];
-      Reductions[0][0][hd][mc] = Reductions[0][1][hd][mc];
+          Reductions[1][0][d][mc] = Reductions[1][1][d][mc];
+          Reductions[0][0][d][mc] = Reductions[0][1][d][mc];
 
-      if (Reductions[0][0][hd][mc] >= 2)
-          Reductions[0][0][hd][mc] += 1;
-  }
+          // Increase reduction when eval is not improving
+          if (Reductions[0][0][d][mc] >= 2)
+              Reductions[0][0][d][mc] += 1;
+      }
 
   // Init futility move count array
-  for (d = 0; d < 32; ++d)
+  for (int d = 0; d < 16; ++d)
   {
       FutilityMoveCounts[0][d] = int(2.4 + 0.773 * pow(d + 0.00, 1.8));
       FutilityMoveCounts[1][d] = int(2.9 + 1.045 * pow(d + 0.49, 1.8));
@@ -322,18 +320,21 @@ namespace {
                 // re-search, otherwise exit the loop.
                 if (bestValue <= alpha)
                 {
+                    beta = (alpha + beta) / 2;
                     alpha = std::max(bestValue - delta, -VALUE_INFINITE);
 
                     Signals.failedLowAtRoot = true;
                     Signals.stopOnPonderhit = false;
                 }
                 else if (bestValue >= beta)
+                {
+                    alpha = (alpha + beta) / 2;
                     beta = std::min(bestValue + delta, VALUE_INFINITE);
-
+                }
                 else
                     break;
 
-                delta += 3 * delta / 8;
+                delta += delta / 2;
 
                 assert(alpha >= -VALUE_INFINITE && beta <= VALUE_INFINITE);
             }
@@ -406,7 +407,7 @@ namespace {
     Move ttMove, move, excludedMove, bestMove;
     Depth ext, newDepth, predictedDepth;
     Value bestValue, value, ttValue, eval, nullValue, futilityValue;
-    bool inCheck, givesCheck, pvMove, singularExtensionNode, improving;
+    bool inCheck, givesCheck, singularExtensionNode, improving;
     bool captureOrPromotion, dangerous, doFullDepthSearch;
     int moveCount, quietCount;
 
@@ -801,7 +802,6 @@ moves_loop: // When in check and at SpNode search starts from here
           continue;
       }
 
-      pvMove = PvNode && moveCount == 1;
       ss->currentMove = move;
       if (!SpNode && !captureOrPromotion && quietCount < 64)
           quietsSearched[quietCount++] = move;
@@ -850,7 +850,7 @@ moves_loop: // When in check and at SpNode search starts from here
           ss->reduction = DEPTH_ZERO;
       }
       else
-          doFullDepthSearch = !pvMove;
+          doFullDepthSearch = !PvNode || moveCount > 1;
 
       // Step 16. Full depth search, when LMR is skipped or fails high
       if (doFullDepthSearch)
@@ -867,7 +867,7 @@ moves_loop: // When in check and at SpNode search starts from here
       // For PV nodes only, do a full PV search on the first move or after a fail
       // high (in the latter case search only if value < beta), otherwise let the
       // parent node fail low with value <= alpha and to try another move.
-      if (PvNode && (pvMove || (value > alpha && (RootNode || value < beta))))
+      if (PvNode && (moveCount == 1 || (value > alpha && (RootNode || value < beta))))
           value = newDepth <   ONE_PLY ?
                             givesCheck ? -qsearch<PV,  true>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
                                        : -qsearch<PV, false>(pos, ss+1, -beta, -alpha, DEPTH_ZERO)
@@ -896,7 +896,7 @@ moves_loop: // When in check and at SpNode search starts from here
           RootMove& rm = *std::find(RootMoves.begin(), RootMoves.end(), move);
 
           // PV move or new best move ?
-          if (pvMove || value > alpha)
+          if (moveCount == 1 || value > alpha)
           {
               rm.score = value;
               rm.extract_pv_from_tt(pos);
@@ -904,7 +904,7 @@ moves_loop: // When in check and at SpNode search starts from here
               // We record how often the best move has been changed in each
               // iteration. This information is used for time management: When
               // the best move changes frequently, we allocate some more time.
-              if (!pvMove)
+              if (moveCount > 1)
                   ++BestMoveChanges;
           }
           else