PVS-Studio warning V610 for Newton Game Dynamics

dgGoogol dgGoogol::Floor () const
{
  ....
  dgUnsigned64 mask = (-1LL) << (64 - bits);
  ....
}

Most likely this is what should be written here: dgUnsigned64 mask = (~0LLU) << (64 - bits);

This suspicious code was found in Newton Game Dynamics project by PVS-Studio static code analyzer.
Warning message is:
V610 Undefined behavior. Check the shift operator '<<. The left operand '(- 1LL)' is negative. dggoogol.cpp 249

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/