public int getFirstAddr() {
			int minAddr = Integer.MAX_VALUE;
			Enumeration enum_ = usingInstrs.elements();
			while (enum_.hasMoreElements()) {
				InstrInfo info = (InstrInfo) enum_.nextElement();
				if (info.instr.getAddr() < minAddr)
					minAddr = info.instr.getAddr();
			}
			return minAddr;
		}