[llvm] [llvm][CodeGen] Add a new software pipeliner 'Window Scheduler' (PR #84443)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> How do you suggest we handle it now?

Just keep it as is. Please remember to do it next time :)

https://github.com/llvm/llvm-project/pull/84443