Use properlyDominates in RDFLiveness when sorting on dominance.

[pranavb]

Summary

When looking for all reaching definitions, we sort basic blocks on dominance. When sorting looking for properlyDominates() handles the case A == B.

[xbolva00]

llvm/lib/CodeGen/RDFLiveness.cpp

237

llvm::sort

llvm/lib/CodeGen/RDFLiveness.cpp

NodeList Liveness::getAllReachingDefs(RegisterRef RefRR,
   for (auto &Bucket : Blocks) {
     TmpBB.push_back(Bucket.first);
     if (Bucket.second.size() > 2)
       GetOrder(*Bucket.first);
     std::sort(Bucket.second.begin(), Bucket.second.end(), Precedes);
   }
 
   // Sort the blocks with respect to dominance.
   std::sort(TmpBB.begin(), TmpBB.end(), [this](auto A, auto B) {
-    return MDT.dominates(A, B);
+    return MDT.properlyDominates(A, B);
   });
 
   std::vector<NodeId> TmpInst;
   for (auto I = TmpBB.rbegin(), E = TmpBB.rend(); I != E; ++I) {
     auto &Bucket = Blocks[*I];
     TmpInst.insert(TmpInst.end(), Bucket.rbegin(), Bucket.rend());
   }