[llvm] [LoopUnroll] Rotate loop before unrolling inside of UnrollRuntimeLoopRemainder (PR #148243)

[Marek Sedláček via llvm-commits]

mark-sed wrote:

@annamthomas When rewriting the code I have realized that it makes more sense to move the rotation after the failure of checks in `UnrollRuntimeLoopRemainder` and then do the rotation in `LoopUnroll` and call `UnrollRuntimeLoopRemainder` again.

This simplifies `UnrollRuntimeLoopRemainder` (no longer the need to propagate rotation into LoopUnroll) and also this should lower the chances of rotation without unrolling as @fhahn mentioned in the other PR.

https://github.com/llvm/llvm-project/pull/148243