/** {@inheritDoc} */
 @Override
 public boolean isLive(ObjectReference object) {
   if (object.isNull()) return false;
   if (Space.isInSpace(SS.SS0, object)) return SS.hi ? SS.copySpace0.isLive(object) : true;
   if (Space.isInSpace(SS.SS1, object)) return SS.hi ? true : SS.copySpace1.isLive(object);
   return super.isLive(object);
 }
 @Override
 @Inline
 public ObjectReference traceObject(ObjectReference object) {
   if (object.isNull()) return object;
   if (Space.isInSpace(SS.SS0, object))
     return SS.copySpace0.traceObject(this, object, SS.ALLOC_SS);
   if (Space.isInSpace(SS.SS1, object))
     return SS.copySpace1.traceObject(this, object, SS.ALLOC_SS);
   return super.traceObject(object);
 }
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 /**
  * Ensure that the referenced object will not move from this point through to the end of the
  * collection. This can involve forwarding the object if necessary.
  *
  * <p><i>Non-copying collectors do nothing, copying collectors must override this method in each
  * of their trace classes.</i>
  *
  * @param object The object that must not move during the collection.
  * @return True If the object will not move during collection
  */
 public boolean willNotMoveInCurrentCollection(ObjectReference object) {
   if (!VM.activePlan.constraints().movesObjects()) return true;
   if (Space.isInSpace(Plan.LOS, object)) return true;
   if (Space.isInSpace(Plan.IMMORTAL, object)) return true;
   if (Space.isInSpace(Plan.VM_SPACE, object)) return true;
   if (Plan.USE_CODE_SPACE && Space.isInSpace(Plan.SMALL_CODE, object)) return true;
   if (Plan.USE_CODE_SPACE && Space.isInSpace(Plan.LARGE_CODE, object)) return true;
   if (VM.VERIFY_ASSERTIONS)
     VM.assertions._assert(false, "willNotMove not defined properly in subclass");
   return false;
 }
 /**
  * This method is the core method during the trace of the object graph. The role of this method is
  * to:
  *
  * <p>1. Ensure the traced object is not collected. 2. If this is the first visit to the object
  * enqueue it to be scanned. 3. Return the forwarded reference to the object.
  *
  * <p>In this instance, we refer objects in the mark-sweep space to the immixSpace for tracing,
  * and defer to the superclass for all others.
  *
  * @param object The object to be traced.
  * @return The new reference to the same object instance.
  */
 @Inline
 public ObjectReference traceObject(ObjectReference object) {
   if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(Immix.immixSpace.inImmixDefragCollection());
   if (object.isNull()) return object;
   if (Space.isInSpace(Immix.IMMIX, object))
     return Immix.immixSpace.traceObject(this, object, Plan.ALLOC_DEFAULT);
   return super.traceObject(object);
 }
 /**
  * Is the specified object live?
  *
  * @param object The object.
  * @return True if the object is live.
  */
 public boolean isLive(ObjectReference object) {
   if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(Immix.immixSpace.inImmixDefragCollection());
   if (object.isNull()) return false;
   if (Space.isInSpace(Immix.IMMIX, object)) {
     return Immix.immixSpace.isLive(object);
   }
   return super.isLive(object);
 }
 /**
  * Collectors that move objects <b>must</b> override this method. It performs the deferred
  * scanning of objects which are forwarded during bootstrap of each copying collection. Because of
  * the complexities of the collection bootstrap (such objects are generally themselves
  * gc-critical), the forwarding and scanning of the objects must be dislocated. It is an error for
  * a non-moving collector to call this method.
  *
  * @param object The forwarded object to be scanned
  */
 @Inline
 @Override
 protected void scanObject(ObjectReference object) {
   if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(Immix.immixSpace.inImmixDefragCollection());
   super.scanObject(object);
   if (MARK_LINE_AT_SCAN_TIME && Space.isInSpace(Immix.IMMIX, object))
     Immix.immixSpace.markLines(object);
 }
 /**
  * Can this object ever move. Used by the VM to make decisions about whether it needs to copy IO
  * buffers etc.
  *
  * @param object The object in question
  * @return True if it is not possible that the object will ever move.
  */
 public boolean willNeverMove(ObjectReference object) {
   if (!VM.activePlan.constraints().movesObjects()) return true;
   if (Space.isInSpace(LOS, object)) return true;
   if (Space.isInSpace(IMMORTAL, object)) return true;
   if (Space.isInSpace(VM_SPACE, object)) return true;
   if (Space.isInSpace(NON_MOVING, object)) return true;
   if (USE_CODE_SPACE && Space.isInSpace(SMALL_CODE, object)) return true;
   if (USE_CODE_SPACE && Space.isInSpace(LARGE_CODE, object)) return true;
   /*
    * Default to false- this preserves correctness over efficiency.
    * Individual plans should override for non-moving spaces they define.
    */
   return false;
 }
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 /**
  * This method is the core method during the trace of the object graph. The role of this method is
  * to:
  *
  * <p>1. Ensure the traced object is not collected. 2. If this is the first visit to the object
  * enqueue it to be scanned. 3. Return the forwarded reference to the object.
  *
  * @param object The object to be traced.
  * @return The new reference to the same object instance.
  */
 @Inline
 public ObjectReference traceObject(ObjectReference object) {
   if (Space.isInSpace(Plan.VM_SPACE, object))
     return (Plan.SCAN_BOOT_IMAGE) ? object : Plan.vmSpace.traceObject(this, object);
   if (Space.isInSpace(Plan.IMMORTAL, object)) return Plan.immortalSpace.traceObject(this, object);
   if (Space.isInSpace(Plan.LOS, object)) return Plan.loSpace.traceObject(this, object);
   if (Space.isInSpace(Plan.PLOS, object)) return Plan.ploSpace.traceObject(this, object);
   if (Plan.USE_CODE_SPACE && Space.isInSpace(Plan.SMALL_CODE, object))
     return Plan.smallCodeSpace.traceObject(this, object);
   if (Plan.USE_CODE_SPACE && Space.isInSpace(Plan.LARGE_CODE, object))
     return Plan.largeCodeSpace.traceObject(this, object);
   if (VM.VERIFY_ASSERTIONS)
     VM.assertions._assert(false, "No special case for space in traceObject");
   return ObjectReference.nullReference();
 }
 /**
  * Will this object move from this point on, during the current trace ?
  *
  * @param object The object to query.
  * @return True if the object will not move.
  */
 @Override
 public boolean willNotMoveInCurrentCollection(ObjectReference object) {
   return (SS.hi && !Space.isInSpace(SS.SS0, object))
       || (!SS.hi && !Space.isInSpace(SS.SS1, object));
 }
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 /**
  * @see org.mmtk.plan.Plan#willNeverMove
  * @param object Object in question
  * @return True if the object will never move
  */
 @Override
 public boolean willNeverMove(ObjectReference object) {
   if (Space.isInSpace(NURSERY, object)) return false;
   return super.willNeverMove(object);
 }
 /**
  * Return true if this object is guaranteed not to move during this collection (i.e. this object
  * is defintely not an unforwarded object).
  *
  * @param object
  * @return True if this object is guaranteed not to move during this collection.
  */
 @Override
 public boolean willNotMoveInCurrentCollection(ObjectReference object) {
   if (VM.VERIFY_ASSERTIONS) VM.assertions._assert(Immix.immixSpace.inImmixDefragCollection());
   if (Space.isInSpace(Immix.IMMIX, object)) return Immix.immixSpace.willNotMoveThisGC(object);
   return true;
 }