message: Add pruning steps to saved model importer paths
diff: @@ -2863,6 +2863,7 @@ StatusOr<mlir::OwningModuleRef> SavedModelObjectGraphImporter::Convert(
  saved_model->debug_info() ? *saved_model->debug_info() : dummy_debug_info;
  GraphImportConfig specs;
  + specs.prune_unused_nodes = true;
  mlir::OwningModuleRef module =
  mlir::ModuleOp::create(mlir::UnknownLoc::get(context));
  std::unordered_map<std::string, std::string> tf_name_to_mlir_name;
  @@ -2888,6 +2889,8 @@ StatusOr<mlir::OwningModuleRef> SavedModelObjectGraphImporter::Convert(
  module.get(), &tf_name_to_mlir_name,
  &function_name_uniquifier);
  + TF_RETURN_IF_ERROR(importer.PrepareConvert(graph));
  +
  auto fn_names = graph.flib_def().ListFunctionNames();
  for (const auto& fn_name : fn_names) {
  TF_RETURN_IF_ERROR(importer.ConvertLibFunction(fn_name));
  @@ -3026,6 +3029,7 @@ Status SavedModelSignatureDefImporter::ConvertSignature(
  });
  GraphImportConfig specs;
  + specs.prune_unused_nodes = true;
  specs.inputs = ParseInputArrays(inputs);
  for (auto& output : outputs) specs.outputs.push_back(output.second.name());
  