[llvm] [InstCombine] Improve select simplification based on known bits (PR #97289)

[Yangyu Chen via llvm-commits]

cyyself wrote:

> Can we revert #66740 after landing this patch? @cyyself found that #66740 caused a significant compile-time regression in SLPVectorizer when building RTL simulator for https://github.com/OpenXiangShan/XiangShan.

Yeah. And note that I have a minimal reproduction here: https://github.com/cyyself/verilator-slow-compile-cases/tree/master/XiangShan-136f64975e-0a9b31bb30

You may need some headers in [Verilator](https://github.com/verilator/verilator) to get this being compiled. For most distro, you can directly install a verilator. 

https://github.com/llvm/llvm-project/pull/97289