Remove some difficult to understand C++11 constructs

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 085bca3a8f5fce6370e908bb80b5f75cd199ca02..ee343fafd04033ecda0e411123f6c4671c7130a0 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -137,7 +137,7 @@ namespace {
   HistoryStats History;
   CounterMovesHistoryStats CounterMovesHistory;
   GainsStats Gains;
-  MovesStats Countermoves, Followupmoves;
+  MovesStats Countermoves;
 
   template <NodeType NT, bool SpNode>
   Value search(Position& pos, Stack* ss, Value alpha, Value beta, Depth depth, bool cutNode);
@@ -339,8 +339,7 @@ namespace {
     CounterMovesHistory.clear();
     Gains.clear();
     Countermoves.clear();
-    Followupmoves.clear();
-
+    
     size_t multiPV = Options["MultiPV"];
     Skill skill(Options["Skill Level"]);
 
@@ -595,7 +594,7 @@ namespace {
     {
         ss->currentMove = ttMove; // Can be MOVE_NONE
 
-        // If ttMove is quiet, update killers, history, counter move and followup move on TT hit
+        // If ttMove is quiet, update killers, history, counter move on TT hit
         if (ttValue >= beta && ttMove && !pos.capture_or_promotion(ttMove) && !inCheck)
             update_stats(pos, ss, ttMove, depth, nullptr, 0);
 
@@ -787,11 +786,7 @@ moves_loop: // When in check and at SpNode search starts from here
     Move countermoves[] = { Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].first,
                             Countermoves[pos.piece_on(prevMoveSq)][prevMoveSq].second };
 
-    Square prevOwnMoveSq = to_sq((ss-2)->currentMove);
-    Move followupmoves[] = { Followupmoves[pos.piece_on(prevOwnMoveSq)][prevOwnMoveSq].first,
-                             Followupmoves[pos.piece_on(prevOwnMoveSq)][prevOwnMoveSq].second };
-
-    MovePicker mp(pos, ttMove, depth, History, CounterMovesHistory, countermoves, followupmoves, ss);
+    MovePicker mp(pos, ttMove, depth, History, CounterMovesHistory, countermoves, ss);
     CheckInfo ci(pos);
     value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
     improving =   ss->staticEval >= (ss-2)->staticEval
@@ -964,7 +959,9 @@ moves_loop: // When in check and at SpNode search starts from here
           ss->reduction = reduction<PvNode>(improving, depth, moveCount);
 
           if (   (!PvNode && cutNode)
-              ||  History[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO)
+              ||  History[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO
+              ||  CounterMovesHistory[pos.piece_on(prevMoveSq)][prevMoveSq][pos.piece_on(to_sq(move))][to_sq(move)]
+                + History[pos.piece_on(to_sq(move))][to_sq(move)] < VALUE_ZERO)
               ss->reduction += ONE_PLY;
 
           if (move == countermoves[0] || move == countermoves[1])
@@ -1142,7 +1139,7 @@ moves_loop: // When in check and at SpNode search starts from here
         bestValue = excludedMove ? alpha
                    :     inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
 
-    // Quiet best move: update killers, history, countermoves and followupmoves
+    // Quiet best move: update killers, history and countermoves
     else if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck)
         update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1);
 
@@ -1402,8 +1399,8 @@ moves_loop: // When in check and at SpNode search starts from here
     *pv = MOVE_NONE;
   }
 
-  // update_stats() updates killers, history, countermoves and followupmoves
-  // stats after a fail-high of a quiet move.
+  // update_stats() updates killers, history and countermoves stats after a fail-high
+  // of a quiet move.
 
   void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt) {
 
@@ -1438,7 +1435,6 @@ moves_loop: // When in check and at SpNode search starts from here
     if (is_ok((ss-2)->currentMove) && (ss-1)->currentMove == (ss-1)->ttMove)
     {
         Square prevPrevSq = to_sq((ss-2)->currentMove);
-        Followupmoves.update(pos.piece_on(prevPrevSq), prevPrevSq, move);
 
         // Extra penalty for TT move in previous ply when it gets refuted
         HistoryStats& ttMoveCmh = CounterMovesHistory[pos.piece_on(prevPrevSq)][prevPrevSq];