[llvm] [GlobalIsel] Visit ICmp (PR #105991)

[Thorsten Schütt via llvm-commits]

tschuett wrote:

https://github.com/llvm/llvm-project/blob/533e6bbd0d344a710c491a9eb0ce0ba0852b08cb/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp#L4608
is ported almost exactly in both combiners. 
https://github.com/llvm/llvm-project/blob/main/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
creates freeze instructions while legalizing illegal freeze instructions, but I could not find other places. Both combiners create freeze instruction while combining, e.g,  selects. It is hard to argue that we ported visitFreeze to combine legalization artefacts.

https://github.com/llvm/llvm-project/pull/105991