[llvm] [LV] Vectorize Epilogues for loops with small VF but high IC (PR #108190)

[Julian Nagele via llvm-commits]

juliannagele wrote:

> Reverse ping: do you have plans to finish this soon'ish? My patch depends on this, i.e. the bit of extra `Multiplier` logic. If you don't have any plans then I could consider integrating that into my patch to break the dependency and unblock that work. Let me know what you think.

One of the test failures was a bit fragile (it arguably shouldn't have passed in the first place), but I should have a separate fix for that. The plan is to finish in the next few days/this week. 

https://github.com/llvm/llvm-project/pull/108190