auto it = buffer_to_size.find(length.getInputHandle());
  if (it == buffer_to_size.end()) {
    length.emitOpError("found tf.TensorListLength on unknown TensorList.");
    return failure();
  }
  OpBuilder builder(length);
  if (it->getSecond().fixed) {
    auto dim = cutil::CreateScalarConst(
        mlir::cast<RankedTensorType>(length.getInputHandle().getType())
            .getDimSize(0),