[llvm] [InstCombine] Do not keep samesign when speculatively executing icmps (PR #127007)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

> As an alternative, we can pass UseInstrInfo=false to simplifyICmpInst.

I prefer the method in this patch. It is still legal to use poison-generating flags in inner expressions.

> I mean we should drop samesign at the beginning of `simplifyICmpInst` if `UseInstrInfo` is false.

Both `simplifyICmpInst` and `isImpliedCondition` APIs don't respect this option.


https://github.com/llvm/llvm-project/pull/127007