Cap evaluation based null move extra reduction to three plies

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 7ce54521d043bdc5abd8da660684868b5123f208..6215b083dd22dc3bc2e408d8fbe09c3a076e0bd0 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -187,7 +187,7 @@ void Search::think() {
 
   TimeMgr.init(Limits, RootPos.game_ply(), RootPos.side_to_move());
 
-  int cf = Options["Contempt Factor"] * PawnValueEg / 100; // From centipawns
+  int cf = Options["Contempt"] * PawnValueEg / 100; // From centipawns
   DrawValue[ RootPos.side_to_move()] = VALUE_DRAW - Value(cf);
   DrawValue[~RootPos.side_to_move()] = VALUE_DRAW + Value(cf);
 
@@ -567,8 +567,7 @@ namespace {
         // Null move dynamic reduction based on depth and value
         Depth R =  3 * ONE_PLY
                  + depth / 4
-                 + (abs(beta) < VALUE_KNOWN_WIN ? int(eval - beta) / PawnValueMg * ONE_PLY
-                                                : DEPTH_ZERO);
+                 + std::min(int(eval - beta) / PawnValueMg, 3) * ONE_PLY;
 
         pos.do_null_move(st);
         (ss+1)->skipNullMove = true;
@@ -823,12 +822,10 @@ moves_loop: // When in check and at SpNode search starts from here
       {
           ss->reduction = reduction<PvNode>(improving, depth, moveCount);
 
-          if (!PvNode && cutNode)
+          if (   (!PvNode && cutNode)
+              ||  History[pos.piece_on(to_sq(move))][to_sq(move)] < 0)
               ss->reduction += ONE_PLY;
 
-          else if (History[pos.piece_on(to_sq(move))][to_sq(move)] < 0)
-              ss->reduction += ONE_PLY / 2;
-
           if (move == countermoves[0] || move == countermoves[1])
               ss->reduction = std::max(DEPTH_ZERO, ss->reduction - ONE_PLY);
 
@@ -1422,46 +1419,13 @@ void Thread::idle_loop() {
 
   assert(!this_sp || (this_sp->masterThread == this && searching));
 
-  while (true)
+  while (!exit)
   {
-      // If we are not searching, wait for a condition to be signaled instead of
-      // wasting CPU time polling for work.
-      while (!searching || exit)
-      {
-          if (exit)
-          {
-              assert(!this_sp);
-              return;
-          }
-
-          // Grab the lock to avoid races with Thread::notify_one()
-          mutex.lock();
-
-          // If we are master and all slaves have finished then exit idle_loop
-          if (this_sp && this_sp->slavesMask.none())
-          {
-              mutex.unlock();
-              break;
-          }
-
-          // Do sleep after retesting sleep conditions under lock protection. In
-          // particular we need to avoid a deadlock in case a master thread has,
-          // in the meanwhile, allocated us and sent the notify_one() call before
-          // we had the chance to grab the lock.
-          if (!searching && !exit)
-              sleepCondition.wait(mutex);
-
-          mutex.unlock();
-      }
-
       // If this thread has been assigned work, launch a search
-      if (searching)
+      while (searching)
       {
-          assert(!exit);
-
           Threads.mutex.lock();
 
-          assert(searching);
           assert(activeSplitPoint);
           SplitPoint* sp = activeSplitPoint;
 
@@ -1545,16 +1509,23 @@ void Thread::idle_loop() {
               }
       }
 
-      // If this thread is the master of a split point and all slaves have finished
-      // their work at this split point, return from the idle loop.
+      // Grab the lock to avoid races with Thread::notify_one()
+      mutex.lock();
+
+      // If we are master and all slaves have finished then exit idle_loop
       if (this_sp && this_sp->slavesMask.none())
       {
-          this_sp->mutex.lock();
-          bool finished = this_sp->slavesMask.none(); // Retest under lock protection
-          this_sp->mutex.unlock();
-          if (finished)
-              return;
+          assert(!searching);
+          mutex.unlock();
+          break;
       }
+
+      // If we are not searching, wait for a condition to be signaled instead of
+      // wasting CPU time polling for work.
+      if (!searching && !exit)
+          sleepCondition.wait(mutex);
+
+      mutex.unlock();
   }
 }