Extent blockSize = Extent.fromInt(BlockAllocator.blockSize(blockSizeClass[sizeClass]));
Extent blockSize = Extent.fromIntSignExtend(BlockAllocator.blockSize(blockSizeClass[sizeClass]));
  protected final void sweepBlocks() {    for (int sizeClass = 0; sizeClass < SIZE_CLASSES; sizeClass++) {      Address block = firstBlock.get(sizeClass);      clearBucketList();      Extent blockSize = Extent.fromInt(BlockAllocator.blockSize(blockSizeClass[sizeClass]));      while (!block.isZero()) {        /* first check to see if block is completely free and if possible         * free the entire block */        Address next = BlockAllocator.getNextBlock(block);        int liveness = getLiveness(block, blockSize, SORT_FREE_BLOCKS);        if (liveness == 0)          freeBlock(block, sizeClass);        else if (!LAZY_SWEEP)          setFreeList(block, makeFreeListFromLiveBits(block, sizeClass));        else if (SORT_FREE_BLOCKS)          addToBlockBucket(block, liveness);        block = next;      }      if (SORT_FREE_BLOCKS) reestablishBlockFreeList(sizeClass);    }  }