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

[Sander de Smalen via llvm-commits]

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sdesmalen-arm wrote:

nit:
```suggestion
; IC=3 should be rejected for a loop of TC=5 as there is no VF it could choose that would result in a single VF*IC iteration with at most 1 scalar iteration.
```

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