VM_Interface.preCopyGCInstances();
  protected final void threadLocalPrepare(int count) {    nursery.rebind(nurseryVM);    if (fullHeapGC) {      threadLocalMaturePrepare(count);      if (Plan.usesLOS) los.prepare();    }    VM_Interface.preCopyGCInstances();   // Pre-copy objects the GC uses  }