target computation.
'metadata' is a serialized TPUCompileMetadataProto describing the shapes and
types of the inputs to the computation, as well as a mapping onto the TPU pod
topology.
'producer_name' is a string describing the name of the framework that add support for running this portion of the model on TPUs.
  }];

  let arguments = (ins
    Variadic<TF_Tensor>:$args,