When compile custom_op, got error: failed to legalize operation 'torch.operator' that was explicitly marked illegal

test code:

import pathlib

import torch
from torch_mlir import compiler_utils, torchscript
import numpy as np


@torch.library.custom_op("mylib::numpy_sin", mutates_args=[], schema='(Tensor x) -> Tensor')
def numpy_sin(input_tensor: torch.Tensor) -> torch.Tensor:
    input_np = input_tensor.numpy()
    output_np = np.zeros_like(input_np)
    np.sin(input_np, out=output_np)
    return torch.from_numpy(output_np).to(device=input_tensor.device)


class NumpySinModule(torch.nn.Module):
    def forward(self, a: torch.Tensor) -> torch.Tensor:
        return numpy_sin(a)


def test_custom_numpy_sin(tmp_path):
    inputs = [torch.ones(128, 128, dtype=torch.float)]
    model = NumpySinModule().eval()

    compile_type = compiler_utils.OutputType.TORCH
    result = torchscript.compile(
        model, inputs[0], output_type=compile_type, use_tracing=True, enable_ir_printing=True
    )
    assert torch.allclose(result, inputs[0].sin())


if __name__ == '__main__':
    test_custom_numpy_sin(pathlib.Path('.'))

bottom of error:

>           raise TorchMlirCompilerError(trimmed_message) from None
E           torch_mlir.compiler_utils.TorchMlirCompilerError: Lowering TorchScript IR -> Torch Backend IR failed with the following diagnostics:
E           error: failed to legalize operation 'torch.operator' that was explicitly marked illegal
E           note: see current operation: %3 = "torch.operator"(%2) <{name = "mylib.numpy_sin"}> : (!torch.tensor<[128,128],f32>) -> !torch.tensor<[128,128],f32>
E           
E           
E           python exception: Failure while executing pass pipeline
E           
E           For Torch-MLIR developers, the error can be reproduced with:
E           $ torch-mlir-opt -pass-pipeline='builtin.module(torchscript-module-to-torch-backend-pipeline{backend-legal-ops= extra-library=})' /tmp/NumpySinModule.mlir
E           Add '-mlir-print-ir-after-all -mlir-disable-threading' to get the IR dump for debugging purpose.

Reproduce the failure with the provided NumpySinModule test and the torch-mlir-opt pass pipeline shown in the error. Read the generated TorchScript IR around the torch.operator named mylib.numpy_sin and the backend-legal-ops and extra-library options; done means the custom operation lowers without the legalization error and the allclose assertion passes.