if (OPT_IR.SANITY_CHECK) VM.assert(bb1.next == null); if (OPT_IR.SANITY_CHECK) VM.assert(bb2.prev == null);
if (OPT_IR.SANITY_CHECK) VM._assert(bb1.next == null); if (OPT_IR.SANITY_CHECK) VM._assert(bb2.prev == null);
  void linkInCodeOrder(OPT_BasicBlock bb1, OPT_BasicBlock bb2) {    if (OPT_IR.SANITY_CHECK) VM.assert(bb1.next == null);    if (OPT_IR.SANITY_CHECK) VM.assert(bb2.prev == null);    bb1.append(bb2);    if (bb1 == _lastNode) {      _lastNode = bb2;    }  }