// CHECK-NEXT: [[READ:%.*]] = "tf.ReadVariableOp"([[ARG2]])
  // CHECK-NEXT: [[CLUSTER:%.*]]:2 = "tf_device.cluster_func"([[ARG0]], [[ARG1]], [[READ]])
  // CHECK-SAME: _replication_info = "write", _xla_compile_device_type = "TPU"
  %0:2 = "tf_device.cluster_func"(%arg0, %arg1) {_replication_info = "write", _xla_compile_device_type = "TPU", func = @write_func} : (tensor<i32>, tensor<f32>) -> (tensor<f32>, tensor<i32>)

      "tf.TPUReplicateMetadata"() {_xla_compile_device_type = "TPU", _replication_info = "replicate", device = "device", num_replicas = 1, topology = "topology"} : () -> ()
      "tf.SomeTpuOp"() {_xla_compile_device_type = "TPU", _replication_info = "replicate"} : () -> ()
      "tf.SomeOtherTpuOp"() {_xla_compile_device_type = "TPU", _replication_info = "replicate"} : () -> ()
      tf_executor.yield
    }
    tf_executor.fetch

      "tf.TPUReplicateMetadata"() {_xla_compile_device_type = "TPU", _replication_info = "cluster", device = "device", num_replicas = 1 : i64, topology = "topology"} : () -> ()
      %0 = "tf.opA"(%arg0) {_xla_compile_device_type = "TPU", _replication_info = "cluster"} : (tensor<i1>) -> tensor<i32>

  func.func @missing_num_cores_per_replica() {
    // expected-error@+1 {{requires attribute 'num_cores_per_replica'}}

      "tf.TPUReplicateMetadata"() {_xla_compile_device_type = "TPU", _replication_info = "cluster", num_relicas = 1, num_cores_per_replica = 1, topology = "<topology>", device_assignment = [], padding_map = []} : () -> ()
      %replicated_input = "tf.TPUReplicatedInput"(%arg0) : (tensor<i32>) -> tensor<i32>
      %identity = "tf.Identity"(%replicated_input) {_xla_compile_device_type = "TPU", _replication_info = "cluster"} : (tensor<i32>) -> tensor<i32>

  func.func @missing_compilation_and_replication_attributes() {
    // expected-error@+1 {{'tf_device.cluster_func' op is expected to have either both or none of '_replication_info' and '_xla_compile_device_type' attributes}}

  func.func @converts_cluster() {
    // CHECK: %0:2 = "tf_device.launch"() <{{.*}}> ({
    // CHECK: %compilation_status, %program = "tf._TPUCompileMlir"()

  return success();
}

// Forms clusters with ops of the same `_replication_info` attribute under a
// block.
//
// For a given block, clusters are formed via grouping ops by
// `_replication_info` attributes. For every cluster formed:
//   1. Find associated TPUReplicateMetadata attributes with the same
//      `_replication_info` attribute.
//   2. Find users not in cluster that are interleaved between cluster ops.

    %control = tf_executor.island wraps "tf.TPUReplicateMetadata"() {_tpu_replicate = "cluster", allow_soft_placement = false, computation_shape...

        // already have a cluster assigned to them (via `_replication_info`
        // attribute value).
        // `tf.Identity` op is also treated as special tpu ops since it can play
        // a role as connection between `tf.TPUReplicatedInput` or
        // `tf.TPUPartitionedInput`. For example, we have the follow pseudocode:
        // %0 = tf_executor.island wraps "tf.OpA" (){_replication_info = 'c'}