[llvm] [LoopVectorize] Enable hoisting of runtime checks by default (PR #71538)

[Florian Hahn via llvm-commits]

fhahn wrote:

I had a look and there are some cases where the more lightweight diff-checks are more profitable than the hoisted checks after 32d1197a8faf4c04df5fcd6c0588aa288bc42e35.

One particular case is when the start of the AddRecs in the inner loop is the same AddRec in the outer loop, like in https://github.com/llvm/llvm-project/blob/fd9a777e018d23d258646af613179eebf6df4b34/llvm/test/Transforms/LoopVectorize/runtime-checks-difference.ll#L279

It would probably be good to refine the checks when to pick hoisting vs diff checks

https://github.com/llvm/llvm-project/pull/71538