[llvm] [VPlan] Delay adding canonical IV increment. (PR #82270)

[via llvm-commits]

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@@ -124,6 +124,11 @@ struct VPlanTransforms {
   /// Remove dead recipes from \p Plan.
   static void removeDeadRecipes(VPlan &Plan);
 
+  /// Finalize \p Plan by introducing explicit increments for the canonical
+  /// induction.
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ayalz wrote:

```suggestion
  /// Complete the canonical IV by introducing an explicit increment between its header phi and latch branch on count.
```
this is one step in getting Plan to be ready for code-gen, not necessarily the last one after which Plan has been "Finalized".

https://github.com/llvm/llvm-project/pull/82270