ObjectReference tgt, int metaDataA,
ObjectReference tgt, Offset metaDataA,
  public final void writeBarrier(ObjectReference src, Address slot,                                  ObjectReference tgt, int metaDataA,                                  int metaDataB, int mode) throws InlinePragma {    if (GATHER_WRITE_BARRIER_STATS) wbFast.inc();    if (RefCountSpace.logRequired(src))      writeBarrierSlow(src);    Barriers.performWriteInBarrier(src, slot, tgt, metaDataA, metaDataB, mode);  }