[llvm] [VPlan] Make canonical IV part of the region (PR #156262)

[via llvm-commits]

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@@ -9346,10 +9341,10 @@ static void preparePlanForMainVectorLoop(VPlan &MainPlan, VPlan &EpiPlan) {
   VPPhi *ResumePhi = nullptr;
   if (ResumePhiIter == MainScalarPH->phis().end()) {
     VPBuilder ScalarPHBuilder(MainScalarPH, MainScalarPH->begin());
+    Type *Ty = VPTypeAnalysis(MainPlan).inferScalarType(VectorTC);
     ResumePhi = ScalarPHBuilder.createScalarPhi(
-        {VectorTC,
-         MainPlan.getVectorLoopRegion()->getCanonicalIV()->getStartValue()},
-        {}, "vec.epilog.resume.val");
+        {VectorTC, MainPlan.getOrAddLiveIn(Constant::getNullValue(Ty))}, {},
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ayalz wrote:

Could getConstantInt() be used?

https://github.com/llvm/llvm-project/pull/156262