Node* c = Unary(a, b1.opts().WithName("C").WithAttr("_encapsulate", "F1"));
    Node* d =
        Binary(b, c, b1.opts().WithName("D").WithAttr("_encapsulate", "F1"));
    Node* e = Binary(c, d,
                     b1.opts()
                         .WithName("E")
                         .WithControlInputs({b, d})
                         .WithAttr("_encapsulate", "F1")
                         .WithAttr("_outside", "O1"));

    // restored in `ConstructHostGraph()`.
    TF_RETURN_IF_ERROR(PreprocessEdgesBetweenOutsideCompilations(
        fbody->graph, outside_compilation_attr_name));

    // Encapsulate outside_compilation cluster into function call node.
    auto rewrite_fn = std::make_unique<RewriteOutsideCompilationSubgraphFn>(
        xla_cluster_attr_name, outside_compilation_attr_name, xla_cluster_name,

  let summary = "Walks tf_executor::GraphOp and merges individual tf_executor::IslandOps.";
  let description = [{
    This pass performs whole graph analysis for a graph encapsulated into tf_executor::GraphOp.
    The analysis identifies all IslandOps within the graph which could be merged together.
    The goal is to merge as many islands as possible.

    backend.

    input:  A list of input tensors whose types are T.
    output: A list of output tensors whose types are T.

    call:  Multiple regions, each of which encapsulates the same semantic
           computation but in different forms.
  }];

  let arguments = (ins Variadic<AnyTensor>:$input);

  let results = (outs Variadic<AnyTensor>:$output);