if (item0.getConstant() != null) return true;
	private boolean isConstant(Item item0, BackwardsBranch bb) {				if (item0.getConstant() != null) return true;		int reg = item0.getRegisterNumber();		if (reg >= 0 && (bb.invariantRegisters.contains(reg) || reg >= bb.numLastUpdates)) return true;		return false;	}