[llvm] [AArch64] Add flag to control unrolling for small multi-exit loops (PR #131998)

[Florian Hahn via llvm-commits]

fhahn wrote:

> The option is just for debugging, it is not intended to be customer facing. Just in case we need to disable it again. If -unroll-runtime-multi-exit will reliably turn the option off then that would be be good. It doesn't look like that is how the option works though as it will not override ULO.RuntimeUnrollMultiExit.

I think this was something that was missed when adding `RuntimeUnrollMultiExit`. I think it makes sense for the option to override the profitability heuristic from TTI, same as it overrides the generic profitability heuristics: https://github.com/llvm/llvm-project/pull/134259

https://github.com/llvm/llvm-project/pull/131998