void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure,
                                              CodeBlobClosure* code_roots,
                                              OopClosure* non_root_closure) {

  {- -------------------------------------------
  (1) SharedHeap::process_weak_roots() を呼び出す.
      ---------------------------------------- -}

      SharedHeap::process_weak_roots(root_closure, code_roots, non_root_closure);

  {- -------------------------------------------
  (1) 
      ---------------------------------------- -}

      // "Local" "weak" refs
      for (int i = 0; i < _n_gens; i++) {
        _gens[i]->ref_processor()->weak_oops_do(root_closure);
      }
    }