[Mlir-commits] [mlir] [SCF] Make loop prefectching safe for overflow (PR #172066)

[Krzysztof Drewniak]

https://github.com/krzysz00 requested changes to this pull request.

Ok, so, to restate the block

This change is apparently one possible workaround for a yet-unknown bug.

We shouldn't be landing that sort of thing.

Once the bug is identified, we can, in the future, discuss whether or not `scf.for` has a `nsw` loop iterator - that is, if we've got C's signed-overflow-is-UB semantics here - and apply this patch with a title like "Use the fact that scf.for can't overflow to improve its lowerings"

https://github.com/llvm/llvm-project/pull/172066