Remove `previousDepth` in favor of `completedDepth + 2`

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index b9ba3811e839fea77cf18c6bae61d3c3bc15eb33..c748f1ff4251424b91fb1b8f8b6db5a87057502b 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -242,9 +242,6 @@ void MainThread::search() {
   bestPreviousScore = bestThread->rootMoves[0].score;
   bestPreviousAverageScore = bestThread->rootMoves[0].averageScore;
 
-  for (Thread* th : Threads)
-    th->previousDepth = bestThread->completedDepth;
-
   // Send again PV info if we have a new best thread
   if (bestThread != this)
       sync_cout << UCI::pv(bestThread->rootPos, bestThread->completedDepth) << sync_endl;
@@ -1026,12 +1023,17 @@ moves_loop: // When in check, search starts here
 
               history += 2 * thisThread->mainHistory[us][from_to(move)];
 
+              lmrDepth += history / 7208;
+              lmrDepth = std::max(lmrDepth, -2);
+
               // Futility pruning: parent node (~13 Elo)
               if (   !ss->inCheck
                   && lmrDepth < 13
-                  && ss->staticEval + 103 + 136 * lmrDepth + history / 53 <= alpha)
+                  && ss->staticEval + 103 + 136 * lmrDepth <= alpha)
                   continue;
 
+              lmrDepth = std::max(lmrDepth, 0);
+
               // Prune moves with negative SEE (~4 Elo)
               if (!pos.see_ge(move, Value(-25 * lmrDepth * lmrDepth - 16 * lmrDepth)))
                   continue;
@@ -1048,7 +1050,7 @@ moves_loop: // When in check, search starts here
           // a reduced search on all the other moves but the ttMove and if the
           // result is lower than ttValue minus a margin, then we will extend the ttMove.
           if (   !rootNode
-              &&  depth >= 4 - (thisThread->previousDepth > 24) + 2 * (PvNode && tte->is_pv())
+              &&  depth >= 4 - (thisThread->completedDepth > 22) + 2 * (PvNode && tte->is_pv())
               &&  move == ttMove
               && !excludedMove // Avoid recursive singular search
            /* &&  ttValue != VALUE_NONE Already implicit in the next condition */