[llvm] [LV] Convert scatter w/uniform addr and mask being header mask to scalar store. (PR #172799)

[Florian Hahn via llvm-commits]

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@@ -8045,40 +8126,43 @@ void LoopVectorizationPlanner::buildVPlansWithVPRecipes(ElementCount MinVF,
       OrigLoop, *LI, Legal->getWidestInductionType(),
       getDebugLocFromInstOrOperands(Legal->getPrimaryInduction()), PSE, &LVer);
 
-  VPlanTransforms::simplifyRecipes(*VPlan0);
-  VPlanTransforms::handleEarlyExits(*VPlan0, Legal->hasUncountableEarlyExit());
-  VPlanTransforms::addMiddleCheck(*VPlan0, CM.foldTailByMasking());
-  RUN_VPLAN_PASS_NO_VERIFY(VPlanTransforms::createLoopRegions, *VPlan0);
-
   // Create recipes for header phis.
   VPlanTransforms::createHeaderPhiRecipes(
       *VPlan0, PSE, *OrigLoop, Legal->getInductionVars(),
       Legal->getReductionVars(), Legal->getFixedOrderRecurrences(),
       CM.getInLoopReductions(), Hints.allowReordering());
 
-  if (CM.foldTailByMasking())
-    RUN_VPLAN_PASS_NO_VERIFY(VPlanTransforms::foldTailByMasking, *VPlan0);
-  RUN_VPLAN_PASS_NO_VERIFY(VPlanTransforms::introduceMasksAndLinearize,
-                           *VPlan0);
+  VPlanTransforms::simplifyRecipes(*VPlan0);
 
   auto MaxVFTimes2 = MaxVF * 2;
   for (ElementCount VF = MinVF; ElementCount::isKnownLT(VF, MaxVFTimes2);) {
     VFRange SubRange = {VF, MaxVFTimes2};
     if (auto Plan = tryToBuildVPlanWithVPRecipes(
             std::unique_ptr<VPlan>(VPlan0->duplicate()), SubRange, &LVer)) {
+      // Add the start VF to prevent optimizations on scalar VF.
+      Plan->addVF(SubRange.Start);
+      Plan->setName("Initial VPlan");
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fhahn wrote:

I think you can move this back to the original position, right?

https://github.com/llvm/llvm-project/pull/172799