VM_Address markBitmap = base.add(set<<(LOG_BYTES_IN_ADDRESS+LOG_SET_SIZE));
VM_Address markBitmap = base.add(set<<LOG_BYTES_IN_ADDRESS);
  private final int markedCells(VM_Address block, int sets)    throws VM_PragmaInline {    if (VM_Interface.VerifyAssertions) VM_Interface._assert(MARK_BITS_ONLY);    VM_Address base = block.add(MARK_BITMAP_BASE);    int usedCells = 0;    for (int set = 0; set < sets; set++) {      if (VM_Interface.VerifyAssertions) 	VM_Interface._assert(MARK_BITMAP_BASE == BITMAP_BASE);      VM_Address markBitmap = base.add(set<<(LOG_BYTES_IN_ADDRESS+LOG_SET_SIZE));      VM_Word mark = VM_Magic.getMemoryWord(markBitmap);      for (int i = 0; i < BITS_IN_ADDRESS; i++) { 	if (!(mark.and(VM_Word.fromInt(1<<i)).isZero())) 	  usedCells++;      }    }    return usedCells;  }