auto output_shape = output_type.getShape();

    // output batch = input batch / (block_size * block_size).
    int64_t input_batch = input_shape[0];
    int64_t output_batch = output_shape[0];
    if (static_dims(input_batch, output_batch) &&
        (output_batch * block_size * block_size) != input_batch)
      return op.emitOpError()
             << "requires output batch (dimension 0) to be equal to input "