[llvm] [InstCombine] Support well-defined recurrences in isGuaranteedNotToBeUndefOrPoison (PR #150420)

[David Sherwood via llvm-commits]

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@@ -7657,6 +7717,13 @@ static bool isGuaranteedNotToBeUndefOrPoison(
       }
       if (IsWellDefined)
         return true;
+
+      bool StartNeedsFreeze;
+      if (canFoldFreezeIntoRecurrence(const_cast<PHINode *>(PN),
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david-arm wrote:

Is it worth having a limit on the number of incoming values to make sure we keep compile time under control?

https://github.com/llvm/llvm-project/pull/150420