[PATCH] D81416: [LV][SLP] Interleave to expose ILP for small loops with scalar reductions.

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

In D81416#2096034 <https://reviews.llvm.org/D81416#2096034>, @AaronLiu wrote:

> In D81416#2095961 <https://reviews.llvm.org/D81416#2095961>, @spatel wrote:
>
> > IIUC, we should add a test under test/Transforms/PhaseOrdering with -O2 to show the cooperative effect of the 2 vectorizers rather than a stand-alone SLP test.
> >  If you can push that test with full baseline CHECK lines and then apply this patch and show test diffs, that would make it much easier to tell what is intended with this patch.
>
>
> Thanks for the comment. This patch does not intend to change or test phase ordering. In this patch, we interleave for small loops with scalar reductions which cannot be vectorized by LV, and later on SLP captures the opportunities. Interleaving is done by LV, and vectorization is done by SLP.


We use PhaseOrdering tests to ensure that the end result of >1 IR pass (usually the entire pipeline of -O* settings) produces the expected result. That may be stretching the meaning of PhaseOrdering, but that would be less fragile than the stand-alone SLP test. This patch isn't changing anything in SLP, so the test you are adding to SLP is independent of this patch, right?


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https://reviews.llvm.org/D81416