From: Aram Tumanian <aram_tumanian@ukr.net>
Date: Wed, 21 Dec 2016 11:40:55 +0000 (+0200)
Subject: Don't clear EasyMove in search()
X-Git-Url: https://git.sesse.net/?p=stockfish;a=commitdiff_plain;h=b7b9d7c9c72a987bb497ec2b629d885a06238aa2;ds=sidebyside

Don't clear EasyMove in search()

EasyMove is cleared after every iteration of the
search if the 3rd move in the PV of the main thread
changes from the previous iteration. Therefore,
clearing EasyMove during a search iteration may be
excessive. The tests show that this is indeed unnecessary.
In the new version the EasyMove variable is used only in
the Thread::search function.

STC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 47719 W: 8438 L: 8362 D: 30919

LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 122841 W: 15448 L: 15457 D: 91936

bench: 5468995
---

diff --git a/src/search.cpp b/src/search.cpp
index 75d388b9..33870913 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -1074,13 +1074,6 @@ moves_loop: // When in check search starts from here
 
           if (value > alpha)
           {
-              // If there is an easy move for this position, clear it if unstable
-              if (    PvNode
-                  &&  thisThread == Threads.main()
-                  &&  EasyMove.get(pos.key())
-                  && (move != EasyMove.get(pos.key()) || moveCount > 1))
-                  EasyMove.clear();
-
               bestMove = move;
 
               if (PvNode && !rootNode) // Update pv even in fail-high case