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

[via llvm-commits]

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@@ -1224,6 +1259,11 @@ VPlan *VPlan::duplicate() {
   // else NewTripCount will be created and inserted into Old2NewVPValues when
   // TripCount is cloned. In any case NewPlan->TripCount is updated below.
 
+  if (auto *LoopRegion = getVectorLoopRegion()) {
+    Old2NewVPValues[LoopRegion->getCanonicalIV()] =
+        NewPlan->getVectorLoopRegion()->getCanonicalIV();
+  }
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ayalz wrote:

```suggestion
  if (auto *CanIV = getCanonicalIV())
    Old2NewVPValues[CanIV] = NewPlan->getCanonicalIV();
```
?

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