[VPlan] Rename getBestPlanFor -> getPlanFor (NFC).

As suggested in #103033, more
accurately rename to getPlanFor , as it simplify returns the VPlan for
VF, relying on the fact that there is a single VPlan for each VF at the
moment.

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h

@@ -362,8 +362,9 @@ class LoopVectorizationPlanner {
   /// VF and its cost.
   VectorizationFactor planInVPlanNativePath(ElementCount UserVF);
 
-  /// Return the best VPlan for \p VF.
-  VPlan &getBestPlanFor(ElementCount VF) const;
+  /// Return the VPlan for \p VF. At the moment, there is always a single VPlan
+  /// for each VF.
+  VPlan &getPlanFor(ElementCount VF) const;
 
   /// Compute and return the most profitable vectorization factor. Also collect
   /// all profitable VFs in ProfitableVFs.

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -9487,7 +9487,7 @@ static bool processLoopInVPlanNativePath(
   if (VPlanBuildStressTest || VectorizationFactor::Disabled() == VF)
     return false;
 
-  VPlan &BestPlan = LVP.getBestPlanFor(VF.Width);
+  VPlan &BestPlan = LVP.getPlanFor(VF.Width);
 
   {
     bool AddBranchWeights =
@@ -9967,7 +9967,7 @@ bool LoopVectorizePass::processLoop(Loop *L) {
       ElementCount BestVF = LVP.computeBestVF();
       assert(BestVF.isScalar() &&
              "VPlan cost model and legacy cost model disagreed");
-      VPlan &BestPlan = LVP.getBestPlanFor(BestVF);
+      VPlan &BestPlan = LVP.getPlanFor(BestVF);
       LVP.executePlan(BestVF, IC, BestPlan, Unroller, DT, false);
 
       ORE->emit([&]() {
@@ -9983,7 +9983,7 @@ bool LoopVectorizePass::processLoop(Loop *L) {
       LLVM_DEBUG(dbgs() << "VF picked by VPlan cost model: " << BestVF << "\n");
       assert(VF.Width == BestVF &&
              "VPlan cost model and legacy cost model disagreed");
-      VPlan &BestPlan = LVP.getBestPlanFor(BestVF);
+      VPlan &BestPlan = LVP.getPlanFor(BestVF);
       // Consider vectorizing the epilogue too if it's profitable.
       VectorizationFactor EpilogueVF =
           LVP.selectEpilogueVectorizationFactor(BestVF, IC);
@@ -10009,7 +10009,7 @@ bool LoopVectorizePass::processLoop(Loop *L) {
                                                  ORE, EPI, &LVL, &CM, BFI, PSI,
                                                  Checks);
 
-        VPlan &BestEpiPlan = LVP.getBestPlanFor(EPI.EpilogueVF);
+        VPlan &BestEpiPlan = LVP.getPlanFor(EPI.EpilogueVF);
         VPRegionBlock *VectorLoop = BestEpiPlan.getVectorLoopRegion();
         VPBasicBlock *Header = VectorLoop->getEntryBasicBlock();
         Header->setName("vec.epilog.vector.body");

llvm/lib/Transforms/Vectorize/VPlan.cpp

@@ -1680,11 +1680,11 @@ void LoopVectorizationPlanner::buildVPlans(ElementCount MinVF,
   }
 }
 
-VPlan &LoopVectorizationPlanner::getBestPlanFor(ElementCount VF) const {
+VPlan &LoopVectorizationPlanner::getPlanFor(ElementCount VF) const {
   assert(count_if(VPlans,
                   [VF](const VPlanPtr &Plan) { return Plan->hasVF(VF); }) ==
              1 &&
-         "Best VF has not a single VPlan.");
+         "Multiple VPlans for VF.");
 
   for (const VPlanPtr &Plan : VPlans) {
     if (Plan->hasVF(VF))