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

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

> Would you like me to add the lowering to `AArch64ISD::BSP` here or in a separate PR?

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



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