[llvm] [LoopVectorize] Add support for vectorisation of simple early exit loops (PR #88385)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

LV already support vectorizing early-exit loops for arguably even simpler cases, i.e. the exit counts for all exits can be computed (in that case, the scalar epilogue is run at least once to fix) https://llvm.godbolt.org/z/35v3nzY7K. So it would probably be worth clarifying that in the commit title.


I added some initial comments/questions, but as this patch touches a lot of different things I wasn't yet able to complete a full look through. Hope to make it through all of it by early/mid next week.

https://github.com/llvm/llvm-project/pull/88385