[llvm] [VPlan] Verify dominance for incoming values of phi-like recipes. (PR #124838)

[via llvm-commits]

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@@ -3283,6 +3295,48 @@ class VPScalarIVStepsRecipe : public VPRecipeWithIRFlags,
   }
 };
 
+/// Casting from VPRecipeBase -> VPPhiAccessors is supported for all recipe
+/// types implementing VPPhiAccessors.
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ayalz wrote:

Is this scaffolding needed for `dyn_cast<VPPhiAccessors>(RecipeBase*)` to work, due to its multiple inheritance?

https://github.com/llvm/llvm-project/pull/124838