TF_ASSERT_OK(root.graph()->AddFunctionLibrary(flib_def));

  Node* read = MakeRead(root, "R");
  NameAttrList fn;
  fn.set_name("Const_func");
  Node* symbolic_gradient =
      ops::SymbolicGradient(root, /*input=*/{ops::Const(root, 1.0f)},
                            /*Tout=*/{DT_FLOAT}, fn)
          .output[0]
          .node();

  root.graph()->AddControlEdge(symbolic_gradient, read);

    const Node& node, string* uncompilable_reason) const {
  // There is a SymbolicGradient kernel on the XLA_JIT device, but the gradient
  // is really a kind of function call and will be handled by
  // IsCompilableCall().
  if (node.type_string() == "SymbolicGradient") {
    *uncompilable_reason =
        "SymbolicGradient should be handled by IsCompilableCall().";
    return false;
  }