[llvm] [AArch64] Lower fixed find_last_active to LASTP with SVE2.2 (PR #222534)

[via llvm-commits]

https://github.com/CarolineConcatto commented:

Thank you Vimal for the patch. 
I left some comments, let me know if they are ok

https://github.com/llvm/llvm-project/pull/222534