Save stalemates in TT

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 1d40f8a070bfbe9f64ccd85355985aa54a769916..3d755586d9885c9ee2310307e0feffee808e3d20 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -94,7 +94,7 @@ namespace {
   void id_loop(Position& pos);
   Value value_to_tt(Value v, int ply);
   Value value_from_tt(Value v, int ply);
-  void update_stats(Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt);
+  void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt);
   string uci_pv(const Position& pos, int depth, Value alpha, Value beta);
 
   struct Skill {
@@ -226,14 +226,12 @@ void Search::think() {
   for (size_t i = 0; i < Threads.size(); ++i)
       Threads[i]->maxPly = 0;
 
-  Threads.sleepWhileIdle = Options["Idle Threads Sleep"];
   Threads.timer->run = true;
   Threads.timer->notify_one(); // Wake up the recurring timer
 
   id_loop(RootPos); // Let's start searching !
 
   Threads.timer->run = false; // Stop the timer
-  Threads.sleepWhileIdle = true; // Send idle threads to sleep
 
   if (Options["Write Search Log"])
   {
@@ -885,7 +883,7 @@ moves_loop: // When in check and at SpNode search starts from here
 
           value = -search<NonPV, false>(pos, ss+1, -(alpha+1), -alpha, d, true);
 
-          // Research at intermediate depth if reduction is very high
+          // Re-search at intermediate depth if reduction is very high
           if (value > alpha && ss->reduction >= 4 * ONE_PLY)
           {
               Depth d2 = std::max(newDepth - 2 * ONE_PLY, ONE_PLY);
@@ -1019,18 +1017,18 @@ moves_loop: // When in check and at SpNode search starts from here
     // must be mate or stalemate. If we are in a singular extension search then
     // return a fail low score.
     if (!moveCount)
-        return  excludedMove ? alpha
-              : inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
+        bestValue = excludedMove ? alpha
+                   :     inCheck ? mated_in(ss->ply) : DrawValue[pos.side_to_move()];
+
+    // Quiet best move: update killers, history, countermoves and followupmoves
+    else if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck)
+        update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1);
 
     TT.store(posKey, value_to_tt(bestValue, ss->ply),
              bestValue >= beta  ? BOUND_LOWER :
              PvNode && bestMove ? BOUND_EXACT : BOUND_UPPER,
              depth, bestMove, ss->staticEval);
 
-    // Quiet best move: update killers, history, countermoves and followupmoves
-    if (bestValue >= beta && !pos.capture_or_promotion(bestMove) && !inCheck)
-        update_stats(pos, ss, bestMove, depth, quietsSearched, quietCount - 1);
-
     assert(bestValue > -VALUE_INFINITE && bestValue < VALUE_INFINITE);
 
     return bestValue;
@@ -1267,7 +1265,7 @@ moves_loop: // When in check and at SpNode search starts from here
   // update_stats() updates killers, history, countermoves and followupmoves stats after a fail-high
   // of a quiet move.
 
-  void update_stats(Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt) {
+  void update_stats(const Position& pos, Stack* ss, Move move, Depth depth, Move* quiets, int quietsCnt) {
 
     if (ss->killers[0] != move)
     {
@@ -1462,7 +1460,7 @@ void Thread::idle_loop() {
   {
       // If we are not searching, wait for a condition to be signaled instead of
       // wasting CPU time polling for work.
-      while ((!searching && Threads.sleepWhileIdle) || exit)
+      while (!searching || exit)
       {
           if (exit)
           {
@@ -1537,8 +1535,7 @@ void Thread::idle_loop() {
 
           // Wake up the master thread so to allow it to return from the idle
           // loop in case we are the last slave of the split point.
-          if (    Threads.sleepWhileIdle
-              &&  this != sp->masterThread
+          if (    this != sp->masterThread
               &&  sp->slavesMask.none())
           {
               assert(!sp->masterThread->searching);
@@ -1547,8 +1544,7 @@ void Thread::idle_loop() {
 
           // After releasing the lock we can't access any SplitPoint related data
           // in a safe way because it could have been released under our feet by
-          // the sp master. Also accessing other Thread objects is unsafe because
-          // if we are exiting there is a chance that they are already freed.
+          // the sp master.
           sp->mutex.unlock();
 
           // Try to late join to another split point if none of its slaves has