Word oldValue = ObjectModel.readAvailableBitsWord(object); Word newValue = oldValue.and(MARK_BIT_MASK.not()).or(markState); ObjectModel.writeAvailableBitsWord(object, newValue);
if (MarkSweepLocal.HEADER_MARK_BITS) { writeMarkBit(object); }
  public final void initializeHeader(ObjectReference object)      throws InlinePragma {    Word oldValue = ObjectModel.readAvailableBitsWord(object);    Word newValue = oldValue.and(MARK_BIT_MASK.not()).or(markState);    ObjectModel.writeAvailableBitsWord(object, newValue);  }