[llvm] [InstCombine] Optimize nested select operators into a simpler form. Added test cases (PR #201453)

[via llvm-commits]

asastry108 wrote:

@antoniofrighetto,  thanks for pointing this out.  Seems that this functionality is already handled by a recent change.
Will drop this.

https://github.com/llvm/llvm-project/pull/201453