[NFC]Fix possibly derefer nullptr in ComplexDeinterleavingPass.cpp

[XinWang10]

Summary

Fix static analyzer reports issue, add assert to avoid analyzer report.

[igor.kirillov]

llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp

1039

If there are Muls and they are not processed, then there is no point to continue analysing Addends. Therefore it is better to have an early exit here.

Also Collect function, if it returns true, always would fill either Addends or Muls. That's why there is no way for the control flow to miss either FinalNode check in the original code. So, FinalNode can't be nullptr by that point

[XinWang10]

• add assert instead

[XinWang10]

llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp

1039

Thanks for explanation, make sense here. I want to add assert instead to mute the static analyzer check. Does this look good to you?

[igor.kirillov]

Ok, then!

llvm/lib/CodeGen/ComplexDeinterleavingPass.cpp

if (RealAddends.size() != ImagAddends.size())
     return nullptr;
 
   NodePtr FinalNode;
   if (!RealMuls.empty() || !ImagMuls.empty()) {
     // If there are multiplicands, extract positive addend and use it as an
     // accumulator
     FinalNode = extractPositiveAddend(RealAddends, ImagAddends);
     FinalNode = identifyMultiplications(RealMuls, ImagMuls, FinalNode);
     if (!FinalNode)
       return nullptr;
   }
 
   // Identify and process remaining additions
   if (!RealAddends.empty() || !ImagAddends.empty()) {
     FinalNode = identifyAdditions(RealAddends, ImagAddends, Flags, FinalNode);
     if (!FinalNode)
       return nullptr;
   }
-
+  assert(FinalNode && "FinalNode can not be nullptr here");
   // Set the Real and Imag fields of the final node and submit it
   FinalNode->Real = Real;
   FinalNode->Imag = Imag;
   submitCompositeNode(FinalNode);
   return FinalNode;
 }
 
 bool ComplexDeinterleavingGraph::collectPartialMuls(