[llvm] [VPlan] Update final IV exit value via VPlan. (PR #112147)

[via llvm-commits]

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@@ -137,6 +137,10 @@ struct VPlanTransforms {
 
   /// Lower abstract recipes to concrete ones, that can be codegen'd.
   static void convertToConcreteRecipes(VPlan &Plan);
+
+  static void
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ayalz wrote:

Something like
```suggestion
  /// If there's a single exit block, optimize its phi recipes that use exiting IV values by feeding them precomputed end values instead, possibly taken one step backwards.
  static void
```

https://github.com/llvm/llvm-project/pull/112147