[PATCH] D117480: [IR] Extend llvm.vector.reduce.fadd

Mon Jan 17 07:07:52 PST 2022

lebedev.ri requested changes to this revision.
lebedev.ri added a comment.
This revision now requires changes to proceed.

In D117480#3248511 <https://reviews.llvm.org/D117480#3248511>, @fhahn wrote:

> In D117480#3248421 <https://reviews.llvm.org/D117480#3248421>, @nikic wrote:
>
>> I don't get this change. We already use reassoc FMF to allow a non-ordered reduction, what's the purpose of the new flag?
>>
>> This also needs a LangRef update.
>
> `reassoc` implies 'any order', but in some cases it is desirable to specify a specific order, e.g. for the vector reduction builtin provided by Clang.

I'm not convinced about all this implied complexity.
I think clang will just have to emit expanded form of the reduction in that case.

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https://reviews.llvm.org/D117480