public Enumeration enumerateVertices() { return graph.enumerateNodes(); }
  void computeClosure() {    for (Enumeration e = enumerateVertices(); e.hasMoreElements(); ) {      OPT_ValueGraphVertex v = (OPT_ValueGraphVertex)e.nextElement();      if (v.name instanceof OPT_Register){        if (v.label instanceof OPT_Register) {          if (v.name != v.label) {            OPT_ValueGraphVertex v2 = getVertex(v.label);            if (VM.VerifyAssertions) {              if (v2.name instanceof OPT_Register &&                   v2.label instanceof OPT_Register &&                  v2.label != v2.name) {                VM.assert(false);              }            }             v.copyVertex(v2);          }        }      }    }  }  /**   * Enumerate the vertices in the value graph.   *   * @return an enumeration of the vertices in the value graph   */  public Enumeration enumerateVertices() {    return graph.enumerateNodes();  }