[PATCH] D75981: [LV] Allow large RT checks, if they are a fraction of the scalar cost.

Wed Jul 14 14:23:24 PDT 2021

lebedev.ri added a comment.

Bump :)

In D75981#2841271 <https://reviews.llvm.org/D75981#2841271>, @fhahn wrote:

> I finally had some time to rebase this change and fix the fallout.

Hurray!
It would be good to finally have this resolved.

> In D75981#2662881 <https://reviews.llvm.org/D75981#2662881>, @ebrevnov wrote:
>
>> I don't really understand why we need this separate heuristic for runtime checks. Why don't we simply add cost of runtime checks (possibly with some small scaling to be safe) to total cost of vector loop and just use existing cost model to decide?
>
> That's a good point, but I think that would be better as separate change, because that's a more aggressive change than replacing existing limit. IIUC that's more in line with your D71053 <https://reviews.llvm.org/D71053>.
>
>> Please add regression tests from https://reviews.llvm.org/D71053 to this change set as well.
>
> I'm not sure that there's much benefit at the moment, because there will be no changes. The focus of those tests seems to be more about vectorizing small trip count loops with an epilogue and not the cost of memory runtime checks (there are no memory runtime checks for the test I think)

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https://reviews.llvm.org/D75981