[llvm] [SimplifyCFG] Fold the contiguous wrapping cases into ICmp. (PR #161000)

[Antonio Frighetto via llvm-commits]

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@@ -5718,15 +5718,49 @@ bool SimplifyCFGOpt::simplifyUnreachable(UnreachableInst *UI) {
   return Changed;
 }
 
-static bool casesAreContiguous(SmallVectorImpl<ConstantInt *> &Cases) {
+static bool casesAreContiguous(Value *Condition,
+                               SmallVectorImpl<ConstantInt *> &Cases,
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antoniofrighetto wrote:

I think the function name would deserve an update, e.g., `findContiguousCases` (and maybe return a std::optional struct instead of the three values as out parameters)?

https://github.com/llvm/llvm-project/pull/161000