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

[via llvm-commits]

llvmssh 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?
This is the source code link.: https://github.com/openjdk/jdk8u/blob/master/hotspot/src/share/vm/runtime/synchronizer.cpp  
Function: ObjectSynchronizer::inflate 

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