X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fmovepick.cpp;h=41b85f074ae0994a86c6615707ad03bb5be925b2;hb=d48a304262eb6b96864df11734976b4a57fcc72a;hp=2a090b1b30c38640f0fe2d656d85ecf851fea14e;hpb=431c3ac485386cc10413fc8a3c7d338dcc71602d;p=stockfish

diff --git a/src/movepick.cpp b/src/movepick.cpp
index 2a090b1b..41b85f07 100644
--- a/src/movepick.cpp
+++ b/src/movepick.cpp
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2013 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2014 Marco Costalba, Joona Kiiski, 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
@@ -71,13 +71,14 @@ namespace {
 /// ordering is at the current node.
 
 MovePicker::MovePicker(const Position& p, Move ttm, Depth d, const HistoryStats& h,
-                       Move* cm, Search::Stack* s) : pos(p), history(h), depth(d) {
+                       Move* cm, Move* fm, Search::Stack* s) : pos(p), history(h), depth(d) {
 
   assert(d > DEPTH_ZERO);
 
   cur = end = moves;
   endBadCaptures = moves + MAX_MOVES - 1;
   countermoves = cm;
+  followupmoves = fm;
   ss = s;
 
   if (p.checkers())
@@ -230,15 +231,24 @@ void MovePicker::generate_next() {
       killers[0].move = ss->killers[0];
       killers[1].move = ss->killers[1];
       killers[2].move = killers[3].move = MOVE_NONE;
+      killers[4].move = killers[5].move = MOVE_NONE;
+
+      // Please note that following code is racy and could yield to rare (less
+      // than 1 out of a million) duplicated entries in SMP case. This is harmless.
 
       // Be sure countermoves are different from killers
       for (int i = 0; i < 2; ++i)
-          if (countermoves[i] != cur->move && countermoves[i] != (cur+1)->move)
+          if (   countermoves[i] != (cur+0)->move
+              && countermoves[i] != (cur+1)->move)
               (end++)->move = countermoves[i];
 
-      if (countermoves[1] && countermoves[1] == countermoves[0]) // Due to SMP races
-          killers[3].move = MOVE_NONE;
-
+      // Be sure followupmoves are different from killers and countermoves
+      for (int i = 0; i < 2; ++i)
+          if (   followupmoves[i] != (cur+0)->move
+              && followupmoves[i] != (cur+1)->move
+              && followupmoves[i] != (cur+2)->move
+              && followupmoves[i] != (cur+3)->move)
+              (end++)->move = followupmoves[i];
       return;
 
   case QUIETS_1_S1:
@@ -286,7 +296,7 @@ void MovePicker::generate_next() {
 /// next_move() is the most important method of the MovePicker class. It returns
 /// a new pseudo legal move every time it is called, until there are no more moves
 /// left. It picks the move with the biggest score from a list of generated moves
-/// taking care not returning the ttMove if it has already been searched previously.
+/// taking care not to return the ttMove if it has already been searched.
 template<>
 Move MovePicker::next_move<false>() {
 
@@ -330,7 +340,9 @@ Move MovePicker::next_move<false>() {
               && move != killers[0].move
               && move != killers[1].move
               && move != killers[2].move
-              && move != killers[3].move)
+              && move != killers[3].move
+              && move != killers[4].move
+              && move != killers[5].move)
               return move;
           break;