public abstract class BlockPayload {
    private Block block;

    public Block getBlock() {
        return block;
    }

    public void setBlock(Block block) {
        this.block = block;
    }

    public BlockPointer getPos() {
        return getBlock().getPos();
    }

    public BlockPointer getNextPos() {
        return getBlock().getNextPos();
    }

    protected abstract int getSize();

};

// Checks if `op` is nested in `block`.
bool OpInBlock(Operation* op, Block* block) {
  Block* op_block = op->getBlock();
  while (op_block) {
    if (op_block == block) return true;
    if (auto* parent_op = op_block->getParentOp()) {
      op_block = parent_op->getBlock();
    } else {
      break;
    }
  }
  return false;
}

        nextBlock = 0;
    }

    @Override
    public void attach(BlockPayload block) {
        if (block.getBlock() == null) {
            block.setBlock(new BlockImpl(block));
        }
    }

    @Override
    public void remove(BlockPayload block) {
        BlockImpl blockImpl = (BlockImpl) block.getBlock();
        blockImpl.detach();
    }

    @Override
    public void flush() {
    }

           .DirectControlPredecessors(
               to_merge,
               [&c](Operation* pred) {
                 Operation* const last_c_op = c.ops.back();
                 return last_c_op->getBlock() == pred->getBlock() &&
                        last_c_op->isBeforeInBlock(pred);
               })
           .empty();
  if (has_control_predecessors_after_cluster) {
    return false;
  }

    assert(op && "member operation must be not null");

    for (Operation *user : op->getUsers()) {
      // Skip users in other blocks.
      if (user->getBlock() != op->getBlock()) continue;

      // Skip users is in the `dst_root` or `src_root` clusters, if we'll merge
      // roots they'll become a single cluster and will not violate the
      // dominance property after that.

        store.close();
    }

    @Override
    public void clear() {
        store.clear();
    }

    @Override
    public void remove(BlockPayload block) {
        Block container = block.getBlock();
        store.remove(block);
        freeListBlock.add(container.getPos(), container.getSize());
    }

    @Override
    public <T extends BlockPayload> T readFirst(Class<T> payloadType) {

LogicalResult SortTopologically(Block::iterator begin, Block::iterator end) {
  Block* block = begin->getBlock();
  // Either sort from `begin` to end of block or both `begin` and
  // `end` should belong to the same block.
  assert(end == block->end() ||
         end->getBlock() == block && "ops must be in the same block");

  // Track the ops that still need to be scheduled in a set.

// order of ops in tf_executor.graph.
LogicalResult LiftIslandOpInnerOpsFromGraph(tf_executor::GraphOp graph) {
  auto graph_position = graph.getOperation()->getIterator();
  Block* parent_block = graph.getOperation()->getBlock();
  for (Operation& op : graph.GetBody().without_terminator()) {
    auto island_op = llvm::dyn_cast<tf_executor::IslandOp>(op);
    if (!island_op)
      return op.emitOpError()

    if (args_permutation.empty() || res_permutation.empty()) return;

    mlir::Operation* op = layout_sensitive_interface.getOperation();
    Location loc = op->getLoc();
    OpBuilder builder = OpBuilder::atBlockEnd(op->getBlock());

    auto perm_attr = [&](Permutation permutation) -> DenseIntElementsAttr {
      auto perm_ty = RankedTensorType::get({4}, builder.getIntegerType(64));
      return DenseIntElementsAttr::get(perm_ty, permutation);

      if (mlir::dyn_cast_or_null<BlockArgument>(operand)) continue;
      auto operand_op = operand.getDefiningOp();
      if (IsConstant(operand_op)) continue;
      if (operand_op->getBlock() != op->getBlock()) {
        return WalkResult::interrupt();
      }
    }
    return WalkResult::advance();
  });
  return !walk_result.wasInterrupted();
}

// It reduces the following pattern:
//