message: Exclude flatten.using_ints and cross_entropy_loss because the two operators do not generate backward functions
diff: @@ -145,10 +145,12 @@ _FN_EXCLUDE_FUNCS_WITH_SIMPLE_ATEN_SIG = [
  "aten::conv_transpose2d.input(Tensor input, Tensor weight, Tensor? bias=None, int[2] stride=1, int[2] padding=0, int[2] output_padding=0, int groups=1, int[2] dilation=1) -> Tensor",
  "aten::conv_transpose3d.input(Tensor input, Tensor weight, Tensor? bias=None, int[3] stride=1, int[3] padding=0, int[3] output_padding=0, int groups=1, int[3] dilation=1) -> Tensor",
  "aten::log_softmax.int(Tensor self, int dim, ScalarType? dtype=None) -> Tensor",
  + "aten::cross_entropy_loss(Tensor self, Tensor target, Tensor? weight=None, int reduction=Mean, int ignore_index=-100) -> Tensor",
  "aten::log_softmax.Dimname(Tensor self, Dimname dim, *, ScalarType? dtype=None) -> Tensor",
  "aten::softmax.int(Tensor self, int dim, ScalarType? dtype=None) -> Tensor",
  "aten::softmax.Dimname(Tensor self, Dimname dim, *, ScalarType? dtype=None) -> Tensor",
  "aten::contiguous(Tensor(a) self, *, MemoryFormat memory_format=contiguous_format) -> Tensor(a)",
  + "aten::flatten.using_ints(Tensor(a) self, int start_dim=0, int end_dim=-1) -> Tensor(a)",
  "aten::dropout(Tensor input, float p, bool train) -> Tensor",
  "aten::dropout_(Tensor(a!) self, float p, bool train) -> Tensor(a!)",
  "aten::nll_loss_nd(Tensor self, Tensor target, Tensor? weight=None, int reduction=Mean, int ignore_index=-100) -> Tensor",
  