if (VM.VerifyAssertions) VM.assert (r.scratchObject != null);
if (VM.VerifyAssertions) VM._assert (r.scratchObject != null);
  private OPT_Register guardFind(OPT_Register r)  {    OPT_Register start = r;    if (VM.VerifyAssertions) VM.assert (r.scratchObject != null);    while (r.scratchObject != r) r = (OPT_Register) r.scratchObject;    while (start.scratchObject != r) {      start.scratchObject = r;      start = (OPT_Register) start.scratchObject;    }    return r;  }