public void visitAddress(Address addr) {
   Oop next = heap.newOop(addr.getOopHandleAt(0));
   LivenessPathElement lp =
       new LivenessPathElement(
           null, new NamedFieldIdentifier(baseRootDescription + " @ " + addr));
   rp.put(lp, next);
   markAndTraverse(next);
 }