[llvm] [InstSimplify] Simplify fcmp implied by dominating fcmp (PR #161090)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

This look ok. I'm not a fan of isImpliedByDomCondition() because it's a hack that only supports dominating conditions from a directly preceding branch -- we're going to need ConstantRangeFP support in one of the lattice propagating passes to cover the general case. But I guess it does work for some cases...

https://github.com/llvm/llvm-project/pull/161090