[llvm] [SimplifyCFG] Simplify uncond br with icmp & select (PR #165580)

[Yingwei Zheng via llvm-commits]

https://github.com/dtcxzyw commented:

I'd only keep tryToSimplifyUncondBranchWithICmpSelectInIt and treat icmp as `select (icmp), i1 true, i1 false`. Then we can handle both forms in one function.
```
bool SimplifyCFGOpt::tryToSimplifyUncondBranchWithICmpSelectInIt(
    ICmpInst *ICI, Value *TV, Value *FV, IRBuilder<> &Builder)
```


https://github.com/llvm/llvm-project/pull/165580