[PATCH] D154157: [LV] Cost model for out-of-loop reductions

Mon Jul 3 05:53:05 PDT 2023

nikic added a comment.

In D154157#4468183 <https://reviews.llvm.org/D154157#4468183>, @fhahn wrote:

> From the description, it is not clear why `FMinimum/FMaximum` reductions in particular should be a blocker for vectorizing small trip count loops. What about other reductions?
>
> Given that this is for short trip counts, it might be better/more general to extend the code that computes the minimum trip count needs to negate the overhead of runtime checks to also consider the overhead of computing the final reduction value (see https://github.com/llvm/llvm-project/blob/main/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp#L10047)

Maybe this generalized version would also fix https://github.com/llvm/llvm-project/issues/57476.

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https://reviews.llvm.org/D154157