When an ATen/Custom operator is registered and needs to be dispatched to an OnnxFunction, the input/attribute dtypes of the ATen/Custom operator are compared with the input/attribute dtypes of the OnnxFunction opschemas to find a match. However, if a perfect/exact match is not found, the dispatcher will attempt to find the nearest match with the highest number of input/attribute dtypes matching the OnnxFunction opschemas, while issuing a warning.

There are two types of level that can be triggered in this rule:

  1. NOTE: A perfect match is found, and no warning is issued.

  2. WARNING: The matched OnnxFunction is not a perfect/exact match.

Here are some suggestions based on the WARNING situation:

  1. If there are NO errors or mismatches in the results, it is safe to disregard this warning, as the definition of OnnxFunction schema is usually more stringent.

  2. If there are errors or mismatches in the results, it is recommended to: (a) Enable op_level_debugging to determine if the OnnxFunction might be incorrect. (b) Report the issue to the PyTorch-ONNX team. (c) Create/register a custom symbolic function to replace the default one.


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