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

[David Sherwood via llvm-commits]

david-arm wrote:

> I am not sure about adding a very specialized option for this. Is there a reason we couldnt take the right decision per uarch to start with? It sounds like that is planned down the road already?

Well I was thinking that someone might be targeting a generic CPU with a particular architecture (perhaps this happens when targeting Android?), but still want a way to get the benefit of unrolling multi-exit loops such as std::find. Having said that, if the consensus is to avoid introducing a flag I can remove it?

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