[llvm] [VPlan] Unroll VPReplicateRecipe by VF. (PR #142433)

[Florian Hahn via llvm-commits]

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@@ -7291,6 +7291,7 @@ DenseMap<const SCEV *, Value *> LoopVectorizationPlanner::executePlan(
   // cost model is complete for better cost estimates.
   VPlanTransforms::runPass(VPlanTransforms::unrollByUF, BestVPlan, BestUF,
                            OrigLoop->getHeader()->getContext());
+  VPlanTransforms::runPass(VPlanTransforms::unrollByVF, BestVPlan, BestVF);
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fhahn wrote:

Exposing more folding opportunities is a nice benefit, although besides that I think the main benefits are simpler recipe ::execute and simpler state management (VPTransformState). 

It also encourages more flexible/general recipes and adds utilities that can be useful in the future, e.g. BuildVector for SLP and potentially also allows more accurate cost estimates, by making vector <-> scalar transitions explicit.



https://github.com/llvm/llvm-project/pull/142433