[llvm] [VPlan] Materialize Build(Struct)Vectors for VPReplicateRecipes. (NFCI) (PR #151487)

[via llvm-commits]

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@@ -513,6 +523,8 @@ void VPlanTransforms::replicateByVF(VPlan &Plan, ElementCount VF) {
       vp_depth_first_shallow(Plan.getVectorLoopRegion()->getEntry()));
   auto VPBBsToUnroll =
       concat<VPBasicBlock *>(VPBBsOutsideLoopRegion, VPBBsInsideLoopRegion);
+  DenseMap<VPValue *, SmallVector<VPValue *>> Def2LaneDefs;
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ayalz wrote:

```suggestion
  // A mapping of current VPValue definitions to collections of new VPValues defined per lane. Serves to hook-up potential users of current VPValue definition that are replicated-per-VF later.
  DenseMap<VPValue *, SmallVector<VPValue *>> Def2LaneDefs;
```

https://github.com/llvm/llvm-project/pull/151487