[llvm] [VPlan] First step towards VPlan cost modeling. (PR #67934)

[via llvm-commits]

================
@@ -340,6 +340,9 @@ class LoopVectorizationPlanner {
   /// A builder used to construct the current plan.
   VPBuilder Builder;
 
+  /// Computes the cost of \p Plan for vectorization factor \p VF.
----------------
ayalz wrote:

Ideally a method of VPlan?

https://github.com/llvm/llvm-project/pull/67934