TF_Output dxy_dx, dxy_dy;

  TF_Output outputs[1] = {{xy, 0}};
  TF_Output inputs[1] = {{x, 0}};
  TF_AddGradients(graph_, outputs, 1, inputs, 1, nullptr, s_, &dxy_dx);
  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);

  inputs[0] = {y, 0};
  TF_AddGradients(graph_, outputs, 1, inputs, 1, nullptr, s_, &dxy_dy);
  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);