[PATCH] D111301: [VPlan] Make sure recurrence splice is not inserted between phis.

Fri Nov 5 13:30:54 PDT 2021

fhahn added a comment.

In D111301#3109192 <https://reviews.llvm.org/D111301#3109192>, @Ayal wrote:

> In D111301#3108536 <https://reviews.llvm.org/D111301#3108536>, @fhahn wrote:
>
>> ping :)
>>
>> @Ayal does the clarification why this is needed make sense?
>>
>>> (from inline comment)
>>> Ok I now what phi-like case I originally hit: if the previous value is an induction value! So I think we still need the special handling?
>
> Clarification indeed makes sense, induction feeding a FOR should presumably be handled, not being a 2nd-order recurrence (SOR).
>
> So we may indeed still need the special handling - along with special test(s); perhaps using i-1 inside a "for i" loop?

There should be test coverage already for those cases, in `Transforms/LoopVectorize/induction.ll`, which fails verification from D111302 <https://reviews.llvm.org/D111302> without the current patch.

> Would also be good to address/exclude/cover non-header phis - of replicated regions and blends.

Should those be included in this patch here?

Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D111301/new/

https://reviews.llvm.org/D111301