!fixup use ::isHeader in VPlan verifier.

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp

@@ -73,9 +73,7 @@ bool VPlanVerifier::verifyPhiRecipes(const VPBasicBlock *VPBB) {
   auto RecipeI = VPBB->begin();
   auto End = VPBB->end();
   unsigned NumActiveLaneMaskPhiRecipes = 0;
-  const VPRegionBlock *ParentR = VPBB->getParent();
-  bool IsHeaderVPBB = ParentR && !ParentR->isReplicator() &&
-                      ParentR->getEntryBasicBlock() == VPBB;
+  bool IsHeaderVPBB = VPBlockUtils::isHeader(VPBB, VPDT);
   while (RecipeI != End && RecipeI->isPhi()) {
     if (isa<VPActiveLaneMaskPHIRecipe>(RecipeI))
       NumActiveLaneMaskPhiRecipes++;