[llvm] [EarlyCSE] Fix improper icmp simplification (PR #122043)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> In actual testing, no matter if % 4 is set to null in a multithreaded environment, it seems that there is no running problem when calling _ZN1A5valueEv. Due to optimizations, %4 == null cannot be intercepted.

Can you share the C source code via godbolt?

https://github.com/llvm/llvm-project/pull/122043