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

[via llvm-commits]

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@@ -165,10 +169,14 @@ class LLVM_ABI_FOR_TEST VPValue {
   const VPRecipeBase *getDefiningRecipe() const;
 
   /// Returns true if this VPValue is defined by a recipe.
-  bool hasDefiningRecipe() const { return getDefiningRecipe(); }
+  bool hasDefiningRecipe() const {
+    return SubclassID != VPRegionValueSC && getDefiningRecipe();
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ayalz wrote:

```suggestion
    return SubclassID == VPVRecipeSC;
```
?

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