[llvm] [AArch64][SVE] Add patterns for bit-select instructions. (PR #138689)

[Ricardo Jesus via llvm-commits]

rj-jesus wrote:

> Up to you. I don't mind the refactoring and the improved code generation being within this one PR.

Thanks, that sounds good - I've just updated the PR with the lowering to `AArch64ISD::BSP` and simplified patterns. Please let me know if this is what you had in mind or if I missed anything. :)

https://github.com/llvm/llvm-project/pull/138689