[llvm] [LV] Support tail-folded epilogue loops (PR #208764)

[David Sherwood via llvm-commits]

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@@ -856,6 +856,10 @@ class LoopVectorizationPlanner {
   /// The profitability analysis.
   LoopVectorizationCostModel &CM;
 
+  /// The profitability analysis for epilogue tail-folding.
+  /// Cleared after making cost based decisions.
+  std::unique_ptr<LoopVectorizationCostModel> EpilogueTfCM;
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david-arm wrote:

I need a bit more time to look into this, but @fhahn's suggestion would make the PR a bit simpler and in follow-on PRs we'll have more context to see the bigger picture and how it will be used. It's a bit difficult to review without seeing the whole stack of PRs, or a WIP branch to look.

https://github.com/llvm/llvm-project/pull/208764