private static void checkNonDebugLabel(final Label label) {
		Field f = getLabelStatusField();
		int status = 0;
		try {
			status = f == null ? 0 : ((Integer) f.get(label)).intValue();
		} catch (IllegalAccessException e) {
			throw new Error("Internal error");
		}
		if ((status & 0x01) != 0) {
			throw new IllegalArgumentException(
					"Labels used for debug info cannot be reused for control flow");
		}
	}