[llvm] [InstCombine] Fold inner selects on the same condition in select values (PR #226371)

[Henry Jiang via llvm-commits]

mustartt wrote:

Since this patch doesn't cover multi-use cases, it is still profitable to duplicate some of the intermediate instructions, such as CINC, CNEG, and CINV. The target dependent multi-use cases that are profitable on AArch64: https://github.com/llvm/llvm-project/pull/224992

https://github.com/llvm/llvm-project/pull/226371