[PATCH] D128890: [InstCombine] remove useless insertelement

Mon Jul 4 02:28:26 PDT 2022

RKSimon added a subscriber: dmgreen.
RKSimon added a comment.

In D128890#3627776 <https://reviews.llvm.org/D128890#3627776>, @Chenbing.Zheng wrote:

> In D128890#3624484 <https://reviews.llvm.org/D128890#3624484>, @RKSimon wrote:
>
>> In which case, we need a FIXME comment explaining that this should be removed once scale vectors are supported
>
> In D78895 <https://reviews.llvm.org/D78895>, @huihuiz add this limit for SimplifyDemandedVectorElts. Maybe SimplifyDemandedVectorElts will no longer support scale vectors.

More likely its untested / has edge cases and they haven't the bandwidth to address it yet. @dmgreen is currently dealing with a similar limit that was added in DAG (D128918 <https://reviews.llvm.org/D128918>)

Adding code to foldBitcastExtElt to get around this limitation must be seen as a temporary measure only.

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  https://reviews.llvm.org/D128890/new/

https://reviews.llvm.org/D128890