http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45699
--- Comment #10 from Martin Jambor <jamborm at gcc dot gnu.org> 2010-10-08 16:51:19 UTC --- I think I know what is going on. BINFO_VIRTUALS of the BINFO describing Probability_Model within Parameters pint to a wring thunk of the method Parameters:clone(). Therefore when the call is devirtualized, the this parameter is not adjusted to point to the whole Ptr object and points only to the part representing the Probability_Model ancestor. And so all references to the fields of the object just load garbage.
