[llvm] [VPlan] Refactor VPlan creation, add transform introducing region (NFC). (PR #128419)

[Florian Hahn via llvm-commits]

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@@ -9307,14 +9307,15 @@ LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(VFRange &Range) {
             return !CM.requiresScalarEpilogue(VF.isVector());
           },
           Range);
-  VPlanPtr Plan = VPlan::createInitialVPlan(Legal->getWidestInductionType(),
-                                            PSE, RequiresScalarEpilogueCheck,
-                                            CM.foldTailByMasking(), OrigLoop);
-
+  auto Plan = std::make_unique<VPlan>(OrigLoop);
   // Build hierarchical CFG.
   VPlanHCFGBuilder HCFGBuilder(OrigLoop, LI, *Plan);
   HCFGBuilder.buildHierarchicalCFG();
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fhahn wrote:

Yep that sounds good. I think it would make sense to consolidate  the transforms for initial VPlan construction into a separate `VPlanConstruction.cpp` 

https://github.com/llvm/llvm-project/pull/128419