return stack.getLastUpdate(reg) < branchTarget;
return stack.getLastUpdate(reg) < getBackwardsReach(branchTarget);
	private boolean constantSince(Item item1, int branchTarget) {			int reg = item1.getRegisterNumber();		if (reg >= 0)		return stack.getLastUpdate(reg) < branchTarget;		if (item1.getConstant() != null)			return true;		return false;		}