[llvm] [VPlan] Factor out logic to common compute costs to helper (NFCI). (PR #153361)

[Florian Hahn via llvm-commits]

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@@ -898,6 +898,13 @@ struct VPRecipeWithIRFlags : public VPSingleDefRecipe, public VPIRFlags {
   }
 
   void execute(VPTransformState &State) override = 0;
+
+  /// Compute the cost for this recipe using \p Opcode. If \p IsVector is true,
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fhahn wrote:

I updated the function to just take an VF argument, and set it to 1 if we compute the scalar cost.

https://github.com/llvm/llvm-project/pull/153361