[PATCH] D124867: [SLP][NFC] Pre-commit test showing horizontal reduction preventing FMA

Tue May 17 07:18:27 PDT 2022

wjschmidt added a comment.

In D124867#3506308 <https://reviews.llvm.org/D124867#3506308>, @ABataev wrote:

> In D124867#3506211 <https://reviews.llvm.org/D124867#3506211>, @wjschmidt wrote:
>
>> In D124867#3506146 <https://reviews.llvm.org/D124867#3506146>, @ABataev wrote:
>>
>>> The undefs still here.
>>
>> Yes, see above -- I was unable to find a sequence without the undefs that causes the horizontal reduction to kick in.
>
> Use -slp-threshold option to avoid problems with the cost.

Thanks for the helpful suggestion!  I was able to remove the undefs with a slight adjustment.  I also ran across another FMA-inhibiting variant that I want to look at before re-posting.  I appreciate the feedback.

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https://reviews.llvm.org/D124867