[llvm] [IR] Add new CreateVectorInterleave interface (PR #150931)

[David Sherwood via llvm-commits]

david-arm wrote:

> LGTM. Are there plans to create a method for deinterleave intrinsics too?

Sure I can do that. I originally thought there was more value in the CreateVectorInterleave interface due to requiring the extra checks and wider type creation, with also the potential benefit of constant folding. For a CreateVectorDeinterleave interface there is less work required, however I agree it makes sense to have it for consistency.

https://github.com/llvm/llvm-project/pull/150931