[llvm] [FuncSpec] Update function specialization to handle phi-chains (PR #71442)

[Chuanqi Xu via llvm-commits]

ChuanqiXu9 wrote:

> Closing this PR, a new PR at #72903
> 
> Thanks for the feedback here.

Then let's try to close it actually. Feel open to reopen it if I miss understand anything.

https://github.com/llvm/llvm-project/pull/71442