[llvm] [LV] Add initial support for vectorizing literal struct return values (PR #109833)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

VPlan supports recipes that produce multiple results, e.g. as `VPInterleaveRecipe`. The recipe then would take care of de-interleaving the result, this would help avoid the need to modify various places in VPTransformState.

I might have missed it, but could you make sure that there are tests with struct return values that cannot be widened?

https://github.com/llvm/llvm-project/pull/109833