message: [TF:MLIR] When importing GraphDef to MLIR for tfcompile, set upgrade_legacy flag
  to allow the functionalization of TensorFlow V1 control flow.
diff: @@ -110,7 +110,7 @@ Status ConvertGraphDefToXlaViaMlir(GraphDef graph_def,
  specs.prune_unused_nodes = false;
  specs.convert_legacy_fed_inputs = false;
  specs.graph_as_function = false;
  - specs.upgrade_legacy = false;
  + specs.upgrade_legacy = true;
  TF_RETURN_IF_ERROR(ConvertInputInfo(config, feed_name_remap, &specs));
  TF_RETURN_IF_ERROR(ConvertOutputInfo(config, &specs));
  