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

[Aaron H Liu via Phabricator via llvm-commits]

AaronLiu added a comment.

In D81416#2112569 <https://reviews.llvm.org/D81416#2112569>, @spatel wrote:

> In D81416#2110070 <https://reviews.llvm.org/D81416#2110070>, @AaronLiu wrote:
>
> > I think all the four testcases are related to this patch, and I prefer to keep the testcase in this patch. The four testcases all serve different purposes:
> >
> > - PhaseOrdering/interleave_LV_SLP.ll shows that with the option in this patch on, instructions were vectorized. But which vectorizer make it work? We cannot tell.
> > - Vectorize/LoopVectorize.cpp tells us that LV cannot vectorize the code, but interleave the instructions to expose ILP.
> > - SLPVectorizer/PowerPC/interleave_SLP.ll demonstrates that after interleaving by LV, then SLP captures the opportunities and vectorize the instructions.
> > - The one you added in PhaseOrdering/interleave-vectorization.ll show that without this patch(equivalently with the option in this patch off), the same testcase both LV and SLP cannot vectorize the instructions.
>
>
> This still isn't quite what I was hoping for. Can you just add "-interleave-small-loop-scalar-reduction=true" to the RUN lines of the file I added and update the CHECK lines using the script? I want this patch to show *the diff* in IR for the proposed code change. I can't easily tell what is changing by comparing 2 different files.


The "-interleave-small-loop-scalar-reduction=true" is in the file PhaseOrdering/interleave_LV_SLP.ll already.
If I add "-interleave-small-loop-scalar-reduction=true" to the RUN lines of the file you added(PhaseOrdering/interleave-vectorization.ll) and update the CHECK lines using the script, this will be a completely a dup of the file PhaseOrdering/interleave_LV_SLP.ll in this patch.

In order for "this patch to show *the diff* in IR for the proposed code change" and "easily tell what is changing by comparing 2 different files" in this patch, **can you please remove the file you added?**

I will add "PhaseOrdering/interleave_LV_SLP_false.ll" which will be "-interleave-small-loop-scalar-reduction=false", and compare with current  "PhaseOrdering/interleave_LV_SLP.ll" which is "-interleave-small-loop-scalar-reduction=true".

So we can compare everything in one patch, instead of two patches?

Also this way, there will be no lit failure problems whether change the default option to be "true" or "false".

Thanks!


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