[llvm] [LoopRotate] Rotate loop if this makes exit count computable (PR #162654)

[Marek Sedláček via llvm-commits]

mark-sed wrote:

> Do you have statistics on how many loops now additionally get runtime-unrolled/vectorized and how many extra rotations happen?

@fhahn, Nikita has run the opt benchmark (mentioned above: https://github.com/dtcxzyw/llvm-opt-benchmark/pull/2973) which shows some nice statistics, but I'll try to collect those stats you mentioned and post it here, thank you for the feedback.

https://github.com/llvm/llvm-project/pull/162654