search(): Move nullValue variable into local scope

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index fd38671e3b0c53d8f653b446e3c1cf1c8f7158aa..1572333b9c35085734c06646001b707657d7bb88 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -2,7 +2,7 @@
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
   Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
-  Copyright (C) 2015-2016 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
+  Copyright (C) 2015-2017 Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -75,6 +75,12 @@ namespace {
     return Reductions[PvNode][i][std::min(d / ONE_PLY, 63)][std::min(mn, 63)] * ONE_PLY;
   }
 
+  // History and stats update bonus, based on depth
+  Value stat_bonus(Depth depth) {
+    int d = depth / ONE_PLY ;
+    return Value(d * d + 2 * d - 2);
+  }
+
   // Skill structure is used to implement strength limit
   struct Skill {
     Skill(int l) : level(l) {}
@@ -155,9 +161,6 @@ namespace {
 
   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); }
-
   EasyMoveManager EasyMove;
   Value DrawValue[COLOR_NB];
 
@@ -502,7 +505,7 @@ void Thread::search() {
 
               bool doEasyMove =   rootMoves[0].pv[0] == easyMove
                                && mainThread->bestMoveChanges < 0.03
-                               && Time.elapsed() > Time.optimum() * 5 / 42;
+                               && Time.elapsed() > Time.optimum() * 5 / 44;
 
               if (   rootMoves.size() == 1
                   || Time.elapsed() > Time.optimum() * unstablePvFactor * improvingFactor / 628
@@ -561,7 +564,7 @@ namespace {
     Key posKey;
     Move ttMove, move, excludedMove, bestMove;
     Depth extension, newDepth;
-    Value bestValue, value, ttValue, eval, nullValue;
+    Value bestValue, value, ttValue, eval;
     bool ttHit, inCheck, givesCheck, singularExtensionNode, improving;
     bool captureOrPromotion, doFullDepthSearch, moveCountPruning;
     Piece moved_piece;
@@ -642,14 +645,24 @@ namespace {
                             : (tte->bound() & BOUND_UPPER)))
     {
         // If ttMove is quiet, update move sorting heuristics on TT hit
-        if (ttValue >= beta && ttMove)
+        if (ttMove)
         {
-            if (!pos.capture_or_promotion(ttMove))
-                update_stats(pos, ss, ttMove, nullptr, 0, bonus(depth));
+            if (ttValue >= beta)
+            {
+                if (!pos.capture_or_promotion(ttMove))
+                    update_stats(pos, ss, ttMove, nullptr, 0, stat_bonus(depth));
 
-            // Extra penalty for a quiet TT move in previous ply when it gets refuted
-            if ((ss-1)->moveCount == 1 && !pos.captured_piece())
-                update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, penalty(depth));
+                // Extra penalty for a quiet TT move in previous ply when it gets refuted
+                if ((ss-1)->moveCount == 1 && !pos.captured_piece())
+                    update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
+            }
+            // Penalty for a quiet ttMove that fails low
+            else if (!pos.capture_or_promotion(ttMove))
+            {
+                Value penalty = -stat_bonus(depth + ONE_PLY);
+                thisThread->history.update(pos.side_to_move(), ttMove, penalty);
+                update_cm_stats(ss, pos.moved_piece(ttMove), to_sq(ttMove), penalty);
+            }
         }
         return ttValue;
     }
@@ -755,8 +768,8 @@ namespace {
         Depth R = ((823 + 67 * depth / ONE_PLY) / 256 + std::min((eval - beta) / PawnValueMg, 3)) * ONE_PLY;
 
         pos.do_null_move(st);
-        nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1)
-                                      : - search<NonPV>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true);
+        Value nullValue = depth-R < ONE_PLY ? -qsearch<NonPV, false>(pos, ss+1, -beta, -beta+1)
+                                            : - search<NonPV>(pos, ss+1, -beta, -beta+1, depth-R, !cutNode, true);
         pos.undo_null_move();
 
         if (nullValue >= beta)
@@ -875,7 +888,8 @@ moves_loop: // When in check search starts from here
       moveCountPruning =   depth < 16 * ONE_PLY
                         && moveCount >= FutilityMoveCounts[improving][depth / ONE_PLY];
 
-      // Step 12. Extend checks
+      // Step 12. Extensions
+      // Extend checks
       if (    givesCheck
           && !moveCountPruning
           &&  pos.see_ge(move, VALUE_ZERO))
@@ -901,7 +915,7 @@ moves_loop: // When in check search starts from here
               extension = ONE_PLY;
       }
 
-      // Update the current move (this must be done after singular extension search)
+      // Calculate new depth for this move
       newDepth = depth - ONE_PLY + extension;
 
       // Step 13. Pruning at shallow depth
@@ -953,6 +967,7 @@ moves_loop: // When in check search starts from here
           continue;
       }
 
+      // Update the current move (this must be done after singular extension search)
       ss->currentMove = move;
       ss->counterMoves = &thisThread->counterMoveHistory[moved_piece][to_sq(move)];
 
@@ -986,7 +1001,7 @@ moves_loop: // When in check search starts from here
                            + (fmh  ? (*fmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
                            + (fmh2 ? (*fmh2)[moved_piece][to_sq(move)] : VALUE_ZERO)
                            + thisThread->history.get(~pos.side_to_move(), move)
-                           - 8000; // Correction factor
+                           - 4000; // Correction factor
 
               // Decrease/increase reduction by comparing opponent's stat score
               if (ss->history > VALUE_ZERO && (ss-1)->history < VALUE_ZERO)
@@ -1118,17 +1133,17 @@ moves_loop: // When in check search starts from here
 
         // Quiet best move: update move sorting heuristics
         if (!pos.capture_or_promotion(bestMove))
-            update_stats(pos, ss, bestMove, quietsSearched, quietCount, bonus(depth));
+            update_stats(pos, ss, bestMove, quietsSearched, quietCount, stat_bonus(depth));
 
         // Extra penalty for a quiet TT move in previous ply when it gets refuted
         if ((ss-1)->moveCount == 1 && !pos.captured_piece())
-            update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, penalty(depth));
+            update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, -stat_bonus(depth + ONE_PLY));
     }
     // Bonus for prior countermove that caused the fail low
     else if (    depth >= 3 * ONE_PLY
              && !pos.captured_piece()
              && is_ok((ss-1)->currentMove))
-        update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, bonus(depth));
+        update_cm_stats(ss-1, pos.piece_on(prevSq), prevSq, stat_bonus(depth));
 
     tte->save(posKey, value_to_tt(bestValue, ss->ply),
               bestValue >= beta ? BOUND_LOWER :