[llvm] [InstCombinePHI] Enhance PHI CSE to remove redundant phis (PR #163453)

[Yingwei Zheng via llvm-commits]

https://github.com/dtcxzyw commented:

I'd expect that this fold should be implemented in `simplifySelectInst` and simplify `%1 = select %cmp2, %identicalPhi, %phi -> %identicalPhi`. It is not a strong requirement, so it's up to you.


https://github.com/llvm/llvm-project/pull/163453