// ["__tf_file_prefix"]`.
//
// See `MergeSaveFunctionOpsToMainPass` for details how the file prefix tensor
// ends up at the MLIR @main function's argument.
std::string FindFilePrefixTensorName(const GraphDef& graph_def) {
  for (const NodeDef& node_def : graph_def.node()) {
    if (node_def.op() == FunctionLibraryDefinition::kArgOp) {
      // Matches the `tf_saved_model.index_path = ["__tf_file_prefix"]`.