exprt local_SSAt::edge_guard(locationt from, locationt to) const { if(from->is_goto()) { // big question: taken or not taken? if(to==from->get_target()) return and_exprt(guard_symbol(from), cond_symbol(from)); else return and_exprt(guard_symbol(from), not_exprt(cond_symbol(from))); } else if(from->is_assume()) { return and_exprt(guard_symbol(from), cond_symbol(from)); } else return guard_symbol(from); }