[llvm] [VPlan] Add new VPInstruction ocpode for header mask. (PR #89603)

[via llvm-commits]

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@@ -105,6 +105,10 @@ struct VPlanTransforms {
   /// VPCanonicalIVPHIRecipe is only used to control the loop after
   /// this transformation.
   static void addExplicitVectorLength(VPlan &Plan);
+
+  /// Lower abstract VPInstruction recipes to a concrete sequence of recipes for
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ayalz wrote:

```suggestion
  /// Lower abstract VPInstruction recipes to sequences of concrete recipes for
```


https://github.com/llvm/llvm-project/pull/89603