[llvm] [LoopVectorizer] Add support for partial reductions (PR #92418)

[Florian Hahn via llvm-commits]

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@@ -3597,6 +3656,11 @@ class VPlan {
   /// been modeled in VPlan directly.
   DenseMap<const SCEV *, VPValue *> SCEVToExpansion;
 
+  /// Stores the set of reduction exit instructions that will be scaled to
+  /// a smaller VF in this plan via partial reductions.
+  DenseMap<const Instruction *, PartialReductionChain>
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fhahn wrote:

Does this need to be part of the VPlan class? Ideally all necessary information should be encoded in recipes. If it is just needed for construction VPRecipeBuilder would be a better place.

https://github.com/llvm/llvm-project/pull/92418