[Bug] relax onnx frontend can not support dynamic slice

[irasin]

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Expected behavior

I have a onnx model which only contains a single slice op as below

And I test it with onnxruntime using the data from https://onnx.ai/onnx/operators/onnx__Slice.html

And the answer is right.

And I think relax can run this model too, but it failed.

When I build it with relax onnx frontend, it reported

    raise ValueError("Only constant Slice parameters are currently supported.")
ValueError: Only constant Slice parameters are currently supported.

which is reported by onnx_frontend,py

class Slice(OnnxOpConverter):
    """Converts an onnx Splice node into an equivalent Relax expression."""

    @classmethod
    def _impl_v13(cls, bb, inputs, attr, params):
        # TODO (jwfromm) currently only supports constant parameters.
        data = inputs[0]
        starts = get_constant(inputs[1], params)
        ends = get_constant(inputs[2], params)
        axes = get_constant(inputs[3], params)
        steps = get_constant(inputs[4], params)
        if not all(
            [
                (
                    isinstance(param, (relax.Constant, relax.ShapeExpr, relax.PrimValue))
                    or param is None
                )
                for param in [starts, ends, axes, steps]
            ]
        ):
            raise ValueError("Only constant Slice parameters are currently supported.")

However, I find that a relax op called dynamic_strided_slice exists in https://github.com/apache/tvm/blob/main/python/tvm/relax/op/index.py#L102

I wonder why we can not use it in onnx frontend?
And if we can use it, how should we modify the onnx slice op converter.

Thanks a lot.

Environment

I used the latest main branch of tvm and installed from source on my ubuntu server.

Steps to reproduce

Here is a minmal python scripts to build onnx model and test on relax

from typing import Dict, List, Literal, Optional

import onnx
from onnx import ModelProto, TensorProto, helper, mapping
import onnxruntime
import numpy as np


import tvm
import tvm.testing
from tvm import relax
from tvm.relax.frontend.onnx import from_onnx
from tvm.script import relax as R
from tvm.script import tir as T
from tvm.script import ir as I


bg = np.random.MT19937(0)
rg = np.random.Generator(bg)


def generate_random_value(shape, elem_type) -> np.ndarray:

    # Extract datatype for the input.
    if elem_type:
        dtype = str(onnx.mapping.TENSOR_TYPE_TO_NP_TYPE[elem_type])
    else:
        dtype = "float32"

    # Generate random inputs for each input.
    if dtype == "bool":
        # random_value = np.random.choice(a=[False, True], size=shape)
        random_value = rg.choice(a=[False, True], size=shape)
    elif dtype.startswith("int"):
        # Keep non-zero values
        random_value = rg.integers(low=-63, high=63, size=shape).astype(dtype)
        random_value[random_value <= 0] -= 1
    else:
        random_value = rg.standard_normal(size=shape).astype(dtype)

    return random_value


def generate_random_inputs(
    model: ModelProto, inputs: Optional[Dict[str, np.ndarray]] = None
) -> Dict[str, np.ndarray]:
    input_values = {}
    # Iterate through model inputs and extract their shape.
    for i in model.graph.input:
        if inputs is not None and i.name in inputs and inputs[i.name] is not None:
            input_values[i.name] = inputs[i.name]
            continue
        shape = []
        for dim in i.type.tensor_type.shape.dim:
            shape.append(dim.dim_value)

        input_values[i.name] = generate_random_value(shape, i.type.tensor_type.elem_type)

    return input_values



def check_correctness(
    model: ModelProto,
    inputs: Optional[Dict[str, np.ndarray]] = None,
    ir_version: int = 8,
    opset: int = 14,
    rtol: float = 1e-7,
    atol: float = 1e-5,
) -> None:
    """Run an onnx model in both onnxruntime and TVM through our importer
       confirm that the results match. Otherwise, an exception will be raised.

    Parameters
    ----------
    model: ModelProto
        The input onnx model that should be tested.
    inputs: Optional[Dict[str, np.ndarray]]
        An optional dictionary containing values for each input in the onnx model.
    ir_version: int
        Which version of the onnx IR to use.
    opset: int
        The opset version to use for the onnx importer.
    atol: float
        Set the tolerance of correctness checking. Some ops may be show more
        arithmetic variance than others.
    """
    # Configure model format.
    if ir_version is not None:
        model.ir_version = ir_version
    if opset is not None:
        model.opset_import[0].version = opset

    # If inputs are not provided, extract them from the onnx graph and produce random
    # values that we'll use for testing.
    inputs = generate_random_inputs(model, inputs)

    # Run the model through onnx to get the expected result.
    ort_session = onnxruntime.InferenceSession(
        model.SerializeToString(), providers=["CPUExecutionProvider"]
    )
    ort_output = ort_session.run([], inputs)

    # Convert the onnx model into relax through the onnx importer.
    tvm_model = from_onnx(model, opset=opset, keep_params_in_input=True)
    # Convert operators for inference mode.
    tvm_model = relax.transform.DecomposeOpsForInference()(tvm_model)
    # Legalize any relax ops into tensorir.
    tvm_model = relax.transform.LegalizeOps()(tvm_model)

    # Separate model from parameters.
    tvm_model, params = relax.frontend.detach_params(tvm_model)
    # Compile the relax graph into a VM then run.

    target = "cuda"
    dev = tvm.device(target, 0)

    with tvm.target.Target(target):
        tvm_model = tvm.tir.transform.DefaultGPUSchedule()(tvm_model) 

    with tvm.transform.PassContext(opt_level=3):
        ex = relax.build(tvm_model, target=target)
        vm = relax.VirtualMachine(ex, dev)


    # Prepare inputs.
    input_list = [
        inputs[key.name_hint] for key in tvm_model["main"].params if key.name_hint in inputs
    ]
    if params:
        input_list += params["main"]

    # Run model and check outputs.
    vm.set_input("main", *input_list)
    vm.invoke_stateful("main")
    tvm_output = vm.get_outputs("main")
    # Wrap as a list if there is only one output.
    if len(ort_output) == 1:
        # Do not check the output number for TVM
        # As for sequence output, the TVM output is a Tuple
        # while the ONNX output number is one, which is a list
        tvm_output = [tvm_output]

    def _check_output(tvm_out, ort_out):
        if isinstance(tvm_out, tuple) and isinstance(ort_out, (tvm.runtime.ShapeTuple, list)):
            assert len(tvm_out) == len(ort_out), "Unequal number of outputs"
            for tvm_out_i, ort_out_i in zip(tvm_out, ort_out):
                _check_output(tvm_out_i, ort_out_i)
        elif isinstance(tvm_out, tvm.nd.NDArray) and isinstance(ort_out, np.ndarray):
            tvm.testing.assert_allclose(tvm_out.numpy(), ort_out, rtol=rtol, atol=atol)
        elif isinstance(tvm_out, tvm.runtime.ShapeTuple) and isinstance(ort_out, np.ndarray):
            shape_out = tvm.nd.array([int(i) for i in tvm_out])
            tvm.testing.assert_allclose(shape_out.numpy(), ort_out, rtol=rtol, atol=atol)
        elif isinstance(tvm_out, (int, float, bool)) and isinstance(ort_out, np.ndarray):
            tvm.testing.assert_allclose(np.array(tvm_out), ort_out, rtol=rtol, atol=atol)
        else:
            raise ValueError(f"Unsupported types: {type(tvm_out)}, {type(ort_out)}")

    # Check that number of outputs match.
    assert len(tvm_output) == len(ort_output), "Unequal number of outputs"
    for tvm_out, ort_out in zip(tvm_output, ort_output):
        # TODO Allow configurable tolerance.
        if ort_out is not None:
            _check_output(tvm_out, ort_out)


if __name__ == "__main__":


    data_shape = ["A", "B"]
    output_shape = ["C", "D"]
    starts_shape = [2]
    ends_shape = [2]
    axes_shape = [2]
    steps_shape = [2]

    slice_node = helper.make_node("Slice", inputs=["data", "starts", "ends", "axes", "steps"], outputs=["output"])

    graph = helper.make_graph(
        [slice_node],
        "slice_test",
        inputs=[
            helper.make_tensor_value_info("data", TensorProto.FLOAT, data_shape),
            helper.make_tensor_value_info("starts", TensorProto.INT64, starts_shape),
            helper.make_tensor_value_info("ends", TensorProto.INT64, ends_shape),
            helper.make_tensor_value_info("axes", TensorProto.INT64, axes_shape),
            helper.make_tensor_value_info("steps", TensorProto.INT64, steps_shape),
        ],
        outputs=[helper.make_tensor_value_info("output", TensorProto.FLOAT, output_shape)],

    )

    model = helper.make_model(graph, producer_name="slice_test")
    model.opset_import[0].version = 11
    onnx.checker.check_model(model)
    # onnx.save(model, "slice.onnx")

    # data from https://onnx.ai/onnx/operators/onnx__Slice.html
    inputs = {
        "data": np.array([
            [1, 2, 3, 4],
            [5, 6, 7, 8]]
        ).astype("float32"),
        "starts": np.array([1, 0], "int64"),
        "ends": np.array([2, 3], "int64"),
        "axes": np.array([0, 1], "int64"),
        "steps": np.array([1, 2], "int64"),   
    }
    expected_output = np.array([[5, 7]]).astype("float32")


    import onnxruntime as ort
    session = ort.InferenceSession(model.SerializeToString(), providers=["CPUExecutionProvider"])
    ort_output = session.run([], inputs)
    print(ort_output[0])
    print(expected_output)


    check_correctness(model, inputs)

Triage

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[brilliant-yan]

@irasin May I ask if you have solved this problem? How do you use dynamic_strided_slice? Thx