Check for overflow in Score * int multiplication (#969)

[stockfish] / src / bitboard.h

diff --git a/src/bitboard.h b/src/bitboard.h
index 715f6c4af485bf8bb7f1313601cb6710024ae0f2..e4ccc3595df098da7aaae2cd7249f720f21b0cc1 100644 (file)
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -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
@@ -291,7 +291,7 @@ inline Square lsb(Bitboard b) {
 
 inline Square msb(Bitboard b) {
   assert(b);
-  return Square(63 - __builtin_clzll(b));
+  return Square(63 ^ __builtin_clzll(b));
 }
 
 #elif defined(_WIN64) && defined(_MSC_VER)