!fixup, Remove unused check and functions.

Author: ElvisWang123

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -2677,13 +2677,6 @@ class VPMulAccumulateReductionRecipe : public VPReductionRecipe {
 
   /// Return the non negative flag of the ext recipe.
   bool isNonNeg() const { return IsNonNeg; }
-
-  /// Drop flags in this recipe.
-  void dropPoisonGeneratingFlags() {
-    VPRecipeWithIRFlags::dropPoisonGeneratingFlags();
-    // Also drop the extra flags not in VPRecipeWithIRFlags.
-    this->IsNonNeg = false;
-  }
 };
 
 /// VPReplicateRecipe replicates a given instruction producing multiple scalar

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -1264,17 +1264,10 @@ void VPlanTransforms::clearReductionWrapFlags(VPlan &Plan) {
     if (RK != RecurKind::Add && RK != RecurKind::Mul)
       continue;
 
-    for (VPUser *U : collectUsersRecursively(PhiR)) {
-      // Flags in reduction recipes are control/store by the recurrence
-      // descriptor. Dropping flags for VPExtendedReductionRecipe and
-      // VPMulaccRecipe may drop flags that we don't expect to drop.
-      if (isa<VPReductionRecipe>(U))
-        continue;
-
+    for (VPUser *U : collectUsersRecursively(PhiR))
       if (auto *RecWithFlags = dyn_cast<VPRecipeWithIRFlags>(U)) {
         RecWithFlags->dropPoisonGeneratingFlags();
       }
-    }
   }
 }