[llvm] Reland "[LV]: Teach LV to recursively (de)interleave." (PR #125094)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

I think I may be missing something, I tried to track down the other divergence in the cost model besides the one mentioned in https://github.com/llvm/llvm-project/pull/125008.

But when I tried something like https://github.com/llvm/llvm-project/pull/125434, there seem to be no other differences between the cost models with this patch.

Are there perhaps other cases where computing the cost for binary VPInstructions with underlying instructions isn't enough?

https://github.com/llvm/llvm-project/pull/125094