// Returns whether type can be further refined.
bool CanBeRefined(Type type) {
  auto shape_type = mlir::dyn_cast<ShapedType>(type);
  if (!shape_type) return false;

  // Returns whether type with subtypes can be further refined.
  auto can_refine_subtypes = [](TF::TensorFlowTypeWithSubtype tws) {
    return tws.GetSubtypes().empty() ||
           llvm::any_of(tws.GetSubtypes(), CanBeRefined);
  };