[llvm] [VPlan] Move initial skeleton construction earlier (NFC). (PR #150848)

[Florian Hahn via llvm-commits]

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@@ -8945,10 +8947,14 @@ VPlanPtr LoopVectorizationPlanner::tryToBuildVPlan(VFRange &Range) {
   assert(EnableVPlanNativePath && "VPlan-native path is not enabled.");
 
   auto Plan = VPlanTransforms::buildPlainCFG(OrigLoop, *LI);
-  VPlanTransforms::prepareForVectorization(
-      *Plan, Legal->getWidestInductionType(), PSE, true, false, OrigLoop,
-      getDebugLocFromInstOrOperands(Legal->getPrimaryInduction()), false,
-      Range);
+
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fhahn wrote:

combined into `buildVPlan0`, wdyt?

I tried to combine the comments as well as possibe

https://github.com/llvm/llvm-project/pull/150848