final Object value = jdkField.get(obj);
if (value == null) {
os.setWord(fldOffset, 0);
} else if (value instanceof UnboxedObject) {
final UnboxedObject uobj = (UnboxedObject) value;
os.setWord(fldOffset, uobj.toLong());
} else if (value instanceof Label) {
final Label lbl = (Label) value;
bis.setObjectRef(fldOffset, lbl);
} else {
throw new BuildException("Cannot handle magic type " + value.getClass().getName());