[llvm] [GlobalIsel] Combine logic of icmps (PR #77855)

[Matt Arsenault via llvm-commits]

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@@ -6643,3 +6644,178 @@ bool CombinerHelper::matchSelect(MachineInstr &MI, BuildFnTy &MatchInfo) {
 
   return false;
 }
+
+/// Fold (icmp Pred1 V1, C1) && (icmp Pred2 V2, C2)
+/// or   (icmp Pred1 V1, C1) || (icmp Pred2 V2, C2)
+/// into a single comparison using range-based reasoning.
+/// see InstCombinerImpl::foldAndOrOfICmpsUsingRanges.
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arsenm wrote:

I'd think this would be possible just using tablegen patterns? Is there a way to plug the trickier ConstantRange handling at the end of the precondition into a mostly-tablegened pattern @Pierre-vh 

https://github.com/llvm/llvm-project/pull/77855