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

[Hassnaa Hamdi via llvm-commits]

hassnaaHamdi wrote:

@fhahn I tried your patch, and yes it gave same costs and the patch is needed anyway for the LoopVectorize itself. 
What I'm saying is that I just don't want this patch to get reverted again in the future because of different target cost for 'Add' and 'or' instructions, given that the issue is not related to the interleaving itself, so I don't want to make connection between them.

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