[llvm] [LV] Thread an explicit CM param through VPlan-building/costing helpers (PR #224836)

[Hassnaa Hamdi via llvm-commits]

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@@ -896,15 +896,18 @@ class LoopVectorizationPlanner {
   /// A builder used to construct the current plan.
   VPBuilder Builder;
 
-  /// Computes the cost of \p Plan for vectorization factor \p VF.
+  /// Computes the cost of \p Plan for vectorization factor \p VF, using
+  /// \p EnabledCM as the cost model (the main loop's cost model, or a
+  /// separate one when costing a tail-folded epilogue).
   ///
   /// The current implementation requires access to the
   /// LoopVectorizationLegality to handle inductions and reductions, which is
   /// why it is kept separate from the VPlan-only cost infrastructure.
   ///
   /// TODO: Move to VPlan::cost once the use of LoopVectorizationLegality has
   /// been retired.
-  InstructionCost cost(VPlan &Plan, ElementCount VF, VPRegisterUsage *RU) const;
+  InstructionCost cost(VPlan &Plan, ElementCount VF, VPRegisterUsage *RU,
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hassnaaHamdi wrote:

Yes, I think the same but @fhahn suggested that for the current limited version of the epilogue TF, we can go on with this current approach given that the affected functions here are limited -the vplan building functions and cost function-.

https://github.com/llvm/llvm-project/pull/224836