[Mlir-commits] [mlir] [mlir][DialectUtils] Fix 0 step handling in `constantTripCount` (PR #177329)

[Markus Böck]

zero9178 wrote:

> > I think we must also document this in the scf.for semantics.
> 
> I'm not quite sure what to do with `scf.for` yet. (Allowing "step size 0" or explicitly marking it as UB.) I'd rather discuss that on a separate PR if you don't mind.
> 
> This PR is just updating a helper function that is not specific to `scf.for`. The only functional change is that for "step size 0" it returns `std::nullopt` in some cases. I.e., "static trip count unknown". Imo, that is consistent with the current semantics of `scf.for`.

Makes sense to me, thank you!

https://github.com/llvm/llvm-project/pull/177329