VM_Interface._assert(workDequeue.pop().isZero());
VM_Interface._assert(workDeque.pop().isZero());
  private final void scan(VM_Address object)    throws VM_PragmaInline {    if (VM_Interface.VerifyAssertions)      VM_Interface._assert(workDequeue.pop().isZero());    while (!object.isZero()) {      if (VM_Interface.VerifyAssertions)	VM_Interface._assert(!RCBaseHeader.isGreen(object));      if (RCBaseHeader.isGrey(object)) {	if (RCBaseHeader.isLiveRC(object)) {	  phase = SCAN_BLACK;	  scanBlack(object);	  phase = SCAN;	} else {	  RCBaseHeader.makeWhite(object);	  ScanObject.enumeratePointers(object, scanEnum);	}      }       object = workDequeue.pop();    }  }