[llvm] [LV] Compute register usage for interleaving on VPlan. (PR #126437)

[Yashwant Singh via llvm-commits]

yashssh wrote:

Sure, here's the IR reproducer to be executed via `opt -passes=loop-vectorize reproducer.ll -S -o -` 
[reproducer.txt](https://github.com/user-attachments/files/20118018/reproducer.txt) (changed the file extension to .txt to allow uploading).

The C++ function and the compiler flags used to generate the IR are here https://godbolt.org/z/ebv3nc4hY 


https://github.com/llvm/llvm-project/pull/126437