Introduce lazy evaluation

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 4f4092ffe2bcae830f54ba84fc62c42ede9ab094..45f50a6353c649b1eb80eb1ca6b082a509fbfdde 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
@@ -211,9 +211,8 @@ void Search::clear() {
 
   for (Thread* th : Threads)
   {
-      th->history.clear();
       th->counterMoves.clear();
-      th->fromTo.clear();
+      th->history.clear();
       th->counterMoveHistory.clear();
       th->resetCalls = true;
   }
@@ -316,8 +315,7 @@ void MainThread::search() {
           Depth depthDiff = th->completedDepth - bestThread->completedDepth;
           Value scoreDiff = th->rootMoves[0].score - bestThread->rootMoves[0].score;
 
-          if (   (depthDiff > 0 && scoreDiff >= 0)
-              || (scoreDiff > 0 && depthDiff >= 0))
+          if (scoreDiff > 0 && depthDiff >= 0)
               bestThread = th;
       }
   }
@@ -643,7 +641,7 @@ namespace {
         && (ttValue >= beta ? (tte->bound() & BOUND_LOWER)
                             : (tte->bound() & BOUND_UPPER)))
     {
-        // If ttMove is quiet, update killers, history, counter move on TT hit
+        // If ttMove is quiet, update move sorting heuristics on TT hit
         if (ttValue >= beta && ttMove)
         {
             if (!pos.capture_or_promotion(ttMove))
@@ -984,12 +982,11 @@ moves_loop: // When in check search starts from here
                        && !pos.see_ge(make_move(to_sq(move), from_sq(move)),  VALUE_ZERO))
                   r -= 2 * ONE_PLY;
 
-              ss->history = thisThread->history[moved_piece][to_sq(move)]
-                           +    (cmh  ? (*cmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
-                           +    (fmh  ? (*fmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
-                           +    (fmh2 ? (*fmh2)[moved_piece][to_sq(move)] : VALUE_ZERO)
-                           +    thisThread->fromTo.get(~pos.side_to_move(), move)
-                           -    8000; // Correction factor
+              ss->history =  (cmh  ? (*cmh )[moved_piece][to_sq(move)] : VALUE_ZERO)
+                           + (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
 
               // Decrease/increase reduction by comparing opponent's stat score
               if (ss->history > VALUE_ZERO && (ss-1)->history < VALUE_ZERO)
@@ -1119,7 +1116,7 @@ moves_loop: // When in check search starts from here
     else if (bestMove)
     {
 
-        // Quiet best move: update killers, history and countermoves
+        // Quiet best move: update move sorting heuristics
         if (!pos.capture_or_promotion(bestMove))
             update_stats(pos, ss, bestMove, quietsSearched, quietCount, bonus(depth));
 
@@ -1405,8 +1402,7 @@ moves_loop: // When in check search starts from here
   }
 
 
-  // update_stats() updates killers, history, countermove and countermove plus
-  // follow-up move history when a new quiet best move is found.
+  // update_stats() updates move sorting heuristics when a new quiet best move is found
 
   void update_stats(const Position& pos, Stack* ss, Move move,
                     Move* quiets, int quietsCnt, Value bonus) {
@@ -1419,8 +1415,7 @@ moves_loop: // When in check search starts from here
 
     Color c = pos.side_to_move();
     Thread* thisThread = pos.this_thread();
-    thisThread->fromTo.update(c, move, bonus);
-    thisThread->history.update(pos.moved_piece(move), to_sq(move), bonus);
+    thisThread->history.update(c, move, bonus);
     update_cm_stats(ss, pos.moved_piece(move), to_sq(move), bonus);
 
     if ((ss-1)->counterMoves)
@@ -1432,8 +1427,7 @@ moves_loop: // When in check search starts from here
     // Decrease all the other played quiet moves
     for (int i = 0; i < quietsCnt; ++i)
     {
-        thisThread->fromTo.update(c, quiets[i], -bonus);
-        thisThread->history.update(pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
+        thisThread->history.update(c, quiets[i], -bonus);
         update_cm_stats(ss, pos.moved_piece(quiets[i]), to_sq(quiets[i]), -bonus);
     }
   }