Merge branch 'master' into clusterMergeMaster14

closes https://github.com/official-stockfish/Stockfish/pull/3980

src/thread.h

@@ -1,6 +1,6 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
-  Copyright (C) 2004-2021 The Stockfish developers (see AUTHORS file)
+  Copyright (C) 2004-2022 The Stockfish developers (see AUTHORS file)
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -61,21 +61,19 @@ public:
   Pawns::Table pawnsTable;
   Material::Table materialTable;
   size_t pvIdx, pvLast;
-  RunningAverage doubleExtensionAverage[COLOR_NB];
-  uint64_t nodesLastExplosive;
-  uint64_t nodesLastNormal;
+  RunningAverage complexityAverage;
   std::atomic<uint64_t> nodes, tbHits, TTsaves, bestMoveChanges;
   int selDepth, nmpMinPly;
   Color nmpColor;
-  ExplosionState state;
+  Value bestValue, optimism[COLOR_NB];
 
   Position rootPos;
   StateInfo rootState;
   Search::RootMoves rootMoves;
-  Depth rootDepth, completedDepth;
+  Depth rootDepth, completedDepth, depth;
+  Value rootDelta;
   CounterMoveHistory counterMoves;
   ButterflyHistory mainHistory;
-  LowPlyHistory lowPlyHistory;
   CapturePieceToHistory captureHistory;
   ContinuationHistory continuationHistory[2][2];
   Score trend;
@@ -99,6 +97,7 @@ struct MainThread : public Thread {
 
   double previousTimeReduction;
   Value bestPreviousScore;
+  Value bestPreviousAverageScore;
   Value iterValue[4];
   int callsCnt;
   bool stopOnPonderhit;