[PATCH] D42447: [LV][VPlan] Detect outer loops for explicit vectorization.

[Florian Hahn via Phabricator via llvm-commits]

fhahn added a comment.

In https://reviews.llvm.org/D42447#1033730, @dcaballe wrote:

> Thanks you, Renato and Florian, for your comments.
>
> > this limitation is due to the fact that VPlan based cost-modelling is not implemented yet, right?
>
> Not only. For full outer loop auto-vectorization we'd also need to extend Legal to check for data dependences that prevent the vectorization of outer loops. In loop nests with several outer loops, we'd also need to compare the cost of vectorizing each of them.


Ah yes, that's missing for now, thanks for clearing that up.

>> I think for testing, it would useful to have an option to process all outer loops. The legality checks should filter out any unsupported loops and this way we could test the VPlan native code path on a much wider range of loops. I think it also would be great if we would have a bot that runs at least the test-suite with VPlan native to discover regressions.
> 
> Is -vplan-build-stress-test flag in Patch #3 (https://reviews.llvm.org/D44338) aligned with what you had in mind? :)

Yep, that's along the lines I had in mind. So far the checks are quite limited, but I think it is a good starting point :)


https://reviews.llvm.org/D42447