static L<Instance> heapWalker_pathToGCRoot(Instance i) {
  new L<Instance> path;
  while licensed {
    path.add(i);
    Instance j = i.getNearestGCRootPointer();
    if (j == null) null; // No path to GC root?
    if (j == i) break;
    i = j;
  }
  ret path;
}