[llvm] [AArch64][SLP] Add NFC test cases for floating point reductions (PR #106507)

[David Green via llvm-commits]

davemgreen wrote:

They do look a little high, it sure sounds like a sensible change to make. Do you intend to change them in general or just for -mcpu=neoverse-v2? If they are just a series of faddp's, then we could hopefully produce better costs for every cpu. If so you could remove the -mcpu options from the tests and just add -mattr where needed.

For the SLP tests it might be good to have at least some non-fast tests along with the ones you have.

https://github.com/llvm/llvm-project/pull/106507