[llvm] [VPlan] Update scalar induction resume values in VPlan. (PR #110577)

[Florian Hahn via llvm-commits]

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@@ -10295,23 +10342,16 @@ bool LoopVectorizePass::processLoop(Loop *L) {
                                              RdxDesc.getRecurrenceStartValue());
             }
           } else {
-            // Create induction resume values for both widened pointer and
-            // integer/fp inductions and update the start value of the induction
-            // recipes to use the resume value.
+            // Retrieve the induction resume values for wide inductions from
+            // their original phi nodes in the scalar loop.
             PHINode *IndPhi = nullptr;
-            const InductionDescriptor *ID;
             if (auto *Ind = dyn_cast<VPWidenPointerInductionRecipe>(&R)) {
               IndPhi = cast<PHINode>(Ind->getUnderlyingValue());
-              ID = &Ind->getInductionDescriptor();
             } else {
               auto *WidenInd = cast<VPWidenIntOrFpInductionRecipe>(&R);
               IndPhi = WidenInd->getPHINode();
-              ID = &WidenInd->getInductionDescriptor();
             }
-
-            ResumeV = MainILV.createInductionResumeValue(
-                IndPhi, *ID, getExpandedStep(*ID, ExpandedSCEVs),
-                {EPI.MainLoopIterationCountCheck});
+            ResumeV = IndPhi->getIncomingValueForBlock(L->getLoopPreheader());
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fhahn wrote:

I might be missing something, but the code here sets the start value for the header recipes in the epilogue. We could possibly get it from the ResumePhis in the main vector loop VPlan, but the VPValues would be defined in a different plan?

https://github.com/llvm/llvm-project/pull/110577