[llvm] [AArch64][CostModel] Alter sdiv/srem cost where the divisor is constant (PR #123552)

[David Green via llvm-commits]

https://github.com/davemgreen commented:

Thanks for doing this. The general idea looks good to me, but I haven't had a chance to look into all the numbers yet (or get back to #122236 or #122469 yet). We will need to make sure that scalable sizes work too, AFAIU they will not currently detect constants correctly.

https://github.com/llvm/llvm-project/pull/123552