Remove PvNode template from reduction

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index f9fdc261b16c9185520fa79d7a0d02e0eccdf2a6..5d6babb45f716200c82dd30b2265d9857a0e81b3 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -18,6 +18,7 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#include <algorithm>
 #include <cassert>
 #include <cmath>
 #include <cstring>   // For std::memset
@@ -69,9 +70,9 @@ namespace {
   // Reductions lookup table, initialized at startup
   int Reductions[MAX_MOVES]; // [depth or moveNumber]
 
-  template <bool PvNode> Depth reduction(bool i, Depth d, int mn) {
+  Depth reduction(bool i, Depth d, int mn) {
     int r = Reductions[d / ONE_PLY] * Reductions[mn] / 1024;
-    return ((r + 512) / 1024 + (!i && r > 1024) - PvNode) * ONE_PLY;
+    return ((r + 512) / 1024 + (!i && r > 1024)) * ONE_PLY;
   }
 
   constexpr int futility_move_count(bool improving, int depth) {
@@ -593,7 +594,10 @@ namespace {
     // starts with statScore = 0. Later grandchildren start with the last calculated
     // statScore of the previous grandchild. This influences the reduction rules in
     // LMR which are based on the statScore of parent position.
-    (ss+2)->statScore = 0;
+       if (rootNode)
+               (ss + 4)->statScore = 0;
+       else
+               (ss + 2)->statScore = 0;
 
     // Step 4. Transposition table lookup. We don't want the score of a partial
     // search to overwrite a previous full search TT value, so we use a different
@@ -894,7 +898,7 @@ moves_loop: // When in check, search starts from here
           &&  move == ttMove
           && !rootNode
           && !excludedMove // Avoid recursive singular search
-      /*  &&  ttValue != VALUE_NONE Already implicit in the next condition */
+       /* &&  ttValue != VALUE_NONE Already implicit in the next condition */
           &&  abs(ttValue) < VALUE_KNOWN_WIN
           && (tte->bound() & BOUND_LOWER)
           &&  tte->depth() >= depth - 3 * ONE_PLY
@@ -927,6 +931,13 @@ moves_loop: // When in check, search starts from here
       else if (type_of(move) == CASTLING)
           extension = ONE_PLY;
 
+      // Shuffle extension
+      else if (   PvNode
+               && pos.rule50_count() > 18
+               && depth < 3 * ONE_PLY
+               && ss->ply < 3 * thisThread->rootDepth / ONE_PLY) // To avoid too deep searches
+          extension = ONE_PLY;
+
       // Passed pawn extension
       else if (   move == ss->killers[0]
                && pos.advanced_pawn_push(move)
@@ -953,7 +964,7 @@ moves_loop: // When in check, search starts from here
                   continue;
 
               // Reduced depth of the next LMR search
-              int lmrDepth = std::max(newDepth - reduction<PvNode>(improving, depth, moveCount), DEPTH_ZERO);
+              int lmrDepth = std::max(newDepth - reduction(improving, depth, moveCount), DEPTH_ZERO);
               lmrDepth /= ONE_PLY;
 
               // Countermoves based pruning (~20 Elo)
@@ -996,14 +1007,16 @@ moves_loop: // When in check, search starts from here
       // Step 16. Reduced depth search (LMR). If the move fails high it will be
       // re-searched at full depth.
       if (    depth >= 3 * ONE_PLY
-          &&  moveCount > 1
-          && (!captureOrPromotion || moveCountPruning))
+          &&  moveCount > 1 + 3 * rootNode
+          && (  !captureOrPromotion
+              || moveCountPruning
+              || ss->staticEval + PieceValue[EG][pos.captured_piece()] <= alpha))
       {
-          Depth r = reduction<PvNode>(improving, depth, moveCount);
+          Depth r = reduction(improving, depth, moveCount);
 
           // Decrease reduction if position is or has been on the PV
           if (ttPv)
-              r -= ONE_PLY;
+              r -= 2 * ONE_PLY;
 
           // Decrease reduction if opponent's move count is high (~10 Elo)
           if ((ss-1)->moveCount > 15)
@@ -1194,8 +1207,8 @@ moves_loop: // When in check, search starts from here
   }
 
 
-  // qsearch() is the quiescence search function, which is called by the main
-  // search function with depth zero, or recursively with depth less than ONE_PLY.
+  // qsearch() is the quiescence search function, which is called by the main search
+  // function with zero depth, or recursively with further decreasing depth per call.
   template <NodeType NT>
   Value qsearch(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth) {