[llvm] [IA] Add support for [de]interleave{3,5,7} (PR #139373)

[David Green via llvm-commits]

davemgreen wrote:

Having a single intrinsic would make cost-modelling more accurate. Replacing the fixed width shuffles with a single intrinsic I think would be worth-while, and would fix a number of perf issues in the current design. (We just have to make sure that loops with isomorphic operations do not get accidentally worse).

https://github.com/llvm/llvm-project/pull/139373