[llvm] [SLSR] Skip candidate-basis differences when `SCEVUnknown`s differ (NFC) (PR #217451)

[Justin Fargnoli via llvm-commits]

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@@ -4582,6 +4582,30 @@ bool ScalarEvolution::containsAddRecurrence(const SCEV *S) {
   return FoundAddRec;
 }
 
+bool ScalarEvolution::hasSameSCEVUnknowns(const SCEV *A, const SCEV *B) {
+  auto CacheUnknowns = [&](const SCEV *Root) {
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justinfargnoli wrote:

Discussed offline. 

https://github.com/llvm/llvm-project/pull/217451