[llvm] [LV] Fix crash in epilog vectorization (PR #185480)

[Florian Hahn via llvm-commits]

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@@ -9345,12 +9347,22 @@ static void fixScalarResumeValuesFromBypass(BasicBlock *BypassBlock, Loop *L,
   // Fix induction resume values from the additional bypass block.
   IRBuilder<> BypassBuilder(BypassBlock, BypassBlock->getFirstInsertionPt());
   for (const auto &[IVPhi, II] : LVL.getInductionVars()) {
-    auto *Inc = cast<PHINode>(IVPhi->getIncomingValueForBlock(PH));
+    Value *IncomingFromPH = IVPhi->getIncomingValueForBlock(PH);
     Value *V = createInductionAdditionalBypassValues(
         IVPhi, II, BypassBuilder, ExpandedSCEVs, MainVectorTripCount,
         LVL.getPrimaryInduction());
-    // TODO: Directly add as extra operand to the VPResumePHI recipe.
-    Inc->setIncomingValueForBlock(BypassBlock, V);
+
+    if (auto *Inc = dyn_cast<PHINode>(IncomingFromPH)) {
+      // TODO: Directly add as extra operand to the VPResumePHI recipe.
+      Inc->setIncomingValueForBlock(BypassBlock, V);
+    } else {
+      // If the incoming value from preheader is not a PHI node (e.g., a
+      // constant in functions with GC statepoint), directly add an incoming
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fhahn wrote:

 I don't think the GC state point bit is relevant?

https://github.com/llvm/llvm-project/pull/185480