[llvm] [InstCombine] Fold fcmp of two int-to-fp conversions to an integer compare (PR #210521)

[via llvm-commits]

AZero13 wrote:

> When both integer operands are exactly representable in the float type, comparing their int-to-fp conversions is the same as comparing the integers directly:int->fp never yields NaN and keeps their ordering:
> 
> fcmp pred (uitofp X), (uitofp Y) --> icmp upred X, Y fcmp pred (sitofp X), (sitofp Y) --> icmp spred X, Y
> 
> Fixes #206329

Alive2? 

https://github.com/llvm/llvm-project/pull/210521