[llvm] [LoopVectorize] Improve Vectorization of Low Trip Count Loops (PR #195823)

[Sander de Smalen via llvm-commits]

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sdesmalen-arm wrote:

I would add `MaxVFForTC / EffectiveIC > 1 &&` to the condition, to make sure that we at least end up with vector operations (that would change the behaviour for `sve-low-trip-count-ic-3.ll`) .

It does make me wonder how much we care about this niche case, i.e. a user IC hint combined with a low-trip-count loop that's not fully unrolled before the LV, where the trip count is lower than the target's tail folding threshold.

https://github.com/llvm/llvm-project/pull/195823