Don't do InCheck Pruning at the root of QS

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 433129d9b5737659cacc8a9307d803a9a0e2d30d..ffe724aa10a864d8b3fad173c5a91c5fa9bb7e26 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -68,14 +68,15 @@ namespace {
   const int skipPhase[] = { 0, 1, 0, 1, 2, 3, 0, 1, 2, 3, 4, 5, 0, 1, 2, 3, 4, 5, 6, 7 };
 
   // Razoring and futility margin based on depth
-  const int razor_margin[4] = { 483, 570, 603, 554 };
+  // razor_margin[0] is unused as long as depth >= ONE_PLY in search
+  const int razor_margin[] = { 0, 570, 603, 554 };
   Value futility_margin(Depth d) { return Value(150 * d / ONE_PLY); }
 
   // Futility and reductions lookup tables, initialized at startup
   int FutilityMoveCounts[2][16]; // [improving][depth]
   int Reductions[2][2][64][64];  // [pv][improving][depth][moveNumber]
 
-  // Threshold used for countermoves based pruning.
+  // Threshold used for countermoves based pruning
   const int CounterMovePruneThreshold = 0;
 
   template <bool PvNode> Depth reduction(bool i, Depth d, int mn) {
@@ -195,8 +196,10 @@ void Search::clear() {
       th->counterMoves.clear();
       th->history.clear();
       th->counterMoveHistory.clear();
-      th->counterMoveHistory[NO_PIECE][0].fill(CounterMovePruneThreshold-1);
       th->resetCalls = true;
+      CounterMoveStats& cm = th->counterMoveHistory[NO_PIECE][0];
+      int* t = &cm[NO_PIECE][0];
+      std::fill(t, t + sizeof(cm), CounterMovePruneThreshold - 1);
   }
 
   Threads.main()->previousScore = VALUE_INFINITE;
@@ -562,9 +565,10 @@ namespace {
     if (thisThread->resetCalls.load(std::memory_order_relaxed))
     {
         thisThread->resetCalls = false;
+
         // At low node count increase the checking rate to about 0.1% of nodes
         // otherwise use a default value.
-        thisThread->callsCnt = Limits.nodes ? std::min((int64_t)4096, Limits.nodes / 1024)
+        thisThread->callsCnt = Limits.nodes ? std::min(4096, int(Limits.nodes / 1024))
                                             : 4096;
     }
 
@@ -875,7 +879,7 @@ moves_loop: // When in check search starts from here
       // (alpha-s, beta-s), and just one fails high on (alpha, beta), then that move
       // is singular and should be extended. To verify this we do a reduced search
       // on all the other moves but the ttMove and if the result is lower than
-      // ttValue minus a margin then we extend the ttMove.
+      // ttValue minus a margin then we will extend the ttMove.
       if (    singularExtensionNode
           &&  move == ttMove
           &&  pos.legal(move))
@@ -889,7 +893,7 @@ moves_loop: // When in check search starts from here
           if (value < rBeta)
               extension = ONE_PLY;
       }
-      else if (   givesCheck
+      else if (    givesCheck
                && !moveCountPruning
                &&  pos.see_ge(move, VALUE_ZERO))
           extension = ONE_PLY;
@@ -904,10 +908,11 @@ moves_loop: // When in check search starts from here
       {
           if (   !captureOrPromotion
               && !givesCheck
-              && (!pos.advanced_pawn_push(move) || pos.non_pawn_material() >= 5000))
+              && (!pos.advanced_pawn_push(move) || pos.non_pawn_material() >= Value(5000)))
           {
               // Move count based pruning
-              if (moveCountPruning) {
+              if (moveCountPruning)
+              {
                   skipQuiets = true;
                   continue;
               }
@@ -1126,11 +1131,11 @@ moves_loop: // When in check search starts from here
              && is_ok((ss-1)->currentMove))
         update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth));
 
-    if(!excludedMove)
+    if (!excludedMove)
         tte->save(posKey, value_to_tt(bestValue, ss->ply),
-                      bestValue >= beta ? BOUND_LOWER :
-                      PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
-                      depth, bestMove, ss->staticEval, TT.generation());
+                  bestValue >= beta ? BOUND_LOWER :
+                  PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
+                  depth, bestMove, ss->staticEval, TT.generation());
 
     assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
 
@@ -1278,6 +1283,7 @@ moves_loop: // When in check search starts from here
 
       // Detect non-capture evasions that are candidates to be pruned
       evasionPrunable =    InCheck
+                       &&  depth != DEPTH_ZERO
                        &&  bestValue > VALUE_MATED_IN_MAX_PLY
                        && !pos.capture(move);