bool storeIsNoop(MemoryDef *Def, const MemoryLocation &DefLoc,
                   const Value *DefUO) {
    StoreInst *Store = dyn_cast<StoreInst>(Def->getMemoryInst());
    MemSetInst *MemSet = dyn_cast<MemSetInst>(Def->getMemoryInst());
    Constant *StoredConstant = nullptr;
    if (Store)
      StoredConstant = dyn_cast<Constant>(Store->getOperand(0));
    if (MemSet)
      StoredConstant = dyn_cast<Constant>(MemSet->getValue());

    if (StoredConstant && StoredConstant->isNullValue()) {
      Instruction *DefUOInst = const_cast<Instruction*>(dyn_cast<Instruction>(DefUO));
      if (DefUOInst) {
          if (isCallocLikeFn(DefUOInst, &TLI)) {
            auto *UnderlyingDef = cast<MemoryDef>(MSSA.getMemoryAccess(DefUOInst));
            // If UnderlyingDef is the clobbering access of Def, no instructions
            // between them can modify the memory location.
            auto *ClobberDef =
                MSSA.getSkipSelfWalker()->getClobberingMemoryAccess(Def);
            return UnderlyingDef == ClobberDef;
        }

        if (isMallocLikeFn(DefUOInst, &TLI) && MemSet &&
            cast<CallBase>(DefUOInst)->getOperand(0) == MemSet->getLength()) {
          auto *Malloc = cast<CallInst>(DefUOInst);
          if (DT.dominates(DefUOInst, cast<Instruction>(MemSet)) &&
                  memoryIsNotModifiedBetween(Malloc, MemSet, BatchAA, DL, &DT)) {
              IRBuilder<> IRB(Malloc);
              const DataLayout &DL = Malloc->getModule()->getDataLayout();
              IntegerType *SizeType = DL.getIntPtrType(IRB.GetInsertBlock()->getContext());
              if (Value *Calloc = emitCalloc(ConstantInt::get(SizeType, 1),
                            Malloc->getArgOperand(0), Malloc->getAttributes(), IRB, TLI)) {
                  Malloc->replaceAllUsesWith(Calloc);
                  Malloc->eraseFromParent();
                  return true;
              }
              return false;
          }
        }
      }
    }

    if (!Store)
      return false;