[llvm] Reapply "[VPlan] Remove unused VPExpandSCEVRecipe before expansion" (PR #187233)

[Florian Hahn via llvm-commits]

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@@ -9236,8 +9181,10 @@ static SmallVector<Instruction *> preparePlanForEpilogueVectorLoop(
     auto *ExpandR = dyn_cast<VPExpandSCEVRecipe>(&R);
     if (!ExpandR)
       continue;
-    VPValue *ExpandedVal =
-        Plan.getOrAddLiveIn(ExpandedSCEVs.lookup(ExpandR->getSCEV()));
+    Value *ExpandedSCEV = ExpandedSCEVs.lookup(ExpandR->getSCEV());
+    if (!ExpandedSCEV)
+      continue;
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fhahn wrote:

Sure this would be something to check, would be good to have a test

https://github.com/llvm/llvm-project/pull/187233