Make pass post-condition aware of model changes?

[iksnagreb]

Currently post-conditions are unaware of (potential) model changes, however, it could be interesting to know if the last call of the pass changed the model (or at least reports a potential model change via the PassResult). As an example: I am (ab?)using the pre- and post-condition for two things, logging, which I always want to do, no matter the model state, and rather costly verification of model correctness, which could be skipped for unchanged models.

Right now I see two options for implementing this: Either a state variable as a member of the PassBase tracking the .modified from the last call's PassResult, or alternatively forwarding the entire PassResult to the post-condition (ensures call). The first option would introduce state into the - up until now - stateless PassBase, not sure if that is desired. The second option would probably be a breaking change to the API.

[justinchuby]

For logging and verification, I wonder you can wrap the passes into a new pass (like how you would wrap nn.Modules with an nn.Module), where you will have access to the input model and pass result and will be able to augment it with new logic.

[justinchuby]

Or, you can inherent the PassManager pass for it I suppose?

[justinchuby]

@iksnagreb let me know if the above works for you?

[iksnagreb]

Hm, not sure, I can try, but what I essentially need to do is to put some logic between the self.call(model) and self.ensures(result.model) calls here: https://github.com/onnx/ir-py/blob/main/src/onnx_ir/passes/_pass_infra.py#L127

I could do this by overriding the __call__ method for passes derived from PassBase, which I already do to add stuff before and after, but otherwise wrap the base class implementation to stay compatible. All I really need is access to the PassResult, not just the model, within my post-conditions.