[LV] Don't access loop after executePlan in native path (NFC). (llvm#191277)

Bring native path in line with inner loop path: the loop may become
invalid once we are able to remove the scalar loop in the native path as
well. Match inner loop behavior by reporting vectorization before
executePlan, and using F instead of L->getHeader()->getParent().

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -8661,20 +8661,20 @@ static bool processLoopInVPlanNativePath(
     GeneratedRTChecks Checks(PSE, DT, LI, TTI, CM.CostKind);
     InnerLoopVectorizer LB(L, PSE, LI, DT, TTI, AC, VF.Width, /*UF=*/1, &CM,
                            Checks, BestPlan);
-    LLVM_DEBUG(dbgs() << "Vectorizing outer loop in \""
-                      << L->getHeader()->getParent()->getName() << "\"\n");
+    LLVM_DEBUG(dbgs() << "Vectorizing outer loop in \"" << F->getName()
+                      << "\"\n");
     LVP.addMinimumIterationCheck(BestPlan, VF.Width, /*UF=*/1,
                                  VF.MinProfitableTripCount);
     bool HasBranchWeights =
         hasBranchWeightMD(*L->getLoopLatch()->getTerminator());
     LVP.attachRuntimeChecks(BestPlan, Checks, HasBranchWeights);
 
+    reportVectorization(ORE, L, VF, 1);
+
     LVP.executePlan(VF.Width, /*UF=*/1, BestPlan, LB, DT);
   }
 
-  reportVectorization(ORE, L, VF, 1);
-
-  assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()));
+  assert(!verifyFunction(*F, &dbgs()));
   return true;
 }