[llvm] [LV][NFC] Query UnrollVectorizedLoop before executing the plan (PR #208500)

[Florian Hahn via llvm-commits]

fhahn wrote:

> > Could you add a test for this? How are the checks changed?
> 
> #205102 exposes this issue and causes existing AArch64 LoopVectorize tests to fail:
> 
> ```
> Failed Tests (10):
>   LLVM :: Transforms/LoopVectorize/AArch64/induction-costs-sve.ll
>   LLVM :: Transforms/LoopVectorize/AArch64/interleaving-load-store.ll
>   LLVM :: Transforms/LoopVectorize/AArch64/load-cast-context.ll
>   LLVM :: Transforms/LoopVectorize/AArch64/reduction-recurrence-costs-sve.ll
>   LLVM :: Transforms/LoopVectorize/AArch64/store-costs-sve.ll
>   LLVM :: Transforms/LoopVectorize/AArch64/sve-epilog-vscale-fixed.ll
>   LLVM :: Transforms/LoopVectorize/AArch64/sve2-histcnt-epilogue.ll
>   LLVM :: Transforms/LoopVectorize/AArch64/sve2-histcnt.ll
>   LLVM :: Transforms/LoopVectorize/AArch64/transform-narrow-interleave-to-widen-memory-scalable.ll
>   LLVM :: Transforms/LoopVectorize/AArch64/transform-narrow-interleave-vscale-x-UF-step.ll
> ```
> 
> This patch makes all of them pass without changing their checks. Would you consider those existing tests as good enough?

It would be good to see what exactly are the changes. The description mentions this already being an issue on ARM, could such a test be added?

https://github.com/llvm/llvm-project/pull/208500