[llvm] [AArch64] Add neon bici test for haddu and shadd (PR #84073)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon commented:

Rename - these files are not about BICI they are about the HADD instructions

aarch64-neon-hadd.ll maybe?

https://github.com/llvm/llvm-project/pull/84073