Quiet unused variable warnings in Release builds

[craig.topper]

LGTM

What compiler is warning on this? I thought the build bots usually catch this, but maybe the assignments inside the loop is making some compilers not notice?

[DavidKreitzer]

Thanks, Craig. I noticed it with gcc 4.8.5.

[jwroorda]

Thanks David for spotting and fixing this!

lib/CodeGen/MachinePipeliner.cpp

void SwingSchedulerDAG::checkValidNodeOrder(const NodeSetType &Circuits) const {
   auto CompareKey = [](UnitIndex i1, UnitIndex i2) {
     return std::get<0>(i1) < std::get<0>(i2);
   };
 
   // sort, so that we can perform a binary search
   std::sort(Indices.begin(), Indices.end(), CompareKey);
 
   bool Valid = true;
+  (void)Valid;
   // for each SUnit in the NodeOrder, check whether
   // it appears after both a successor and a predecessor
   // of the SUnit. If this is the case, and the SUnit
   // is not part of circuit, then the NodeOrder is not
   // valid.
   for (unsigned i = 0, s = NodeOrder.size(); i < s; ++i) {
     SUnit *SU = NodeOrder[i];
     unsigned Index = i;
 
     bool PredBefore = false;
     bool SuccBefore = false;
 
     SUnit *Succ;
     SUnit *Pred;
+    (void)Succ;
+    (void)Pred;
 
     for (SDep &PredEdge : SU->Preds) {
       SUnit *PredSU = PredEdge.getSUnit();
       unsigned PredIndex =
           std::get<1>(*std::lower_bound(Indices.begin(), Indices.end(),
                                         std::make_pair(PredSU, 0), CompareKey));
       if (!PredSU->getInstr()->isPHI() && PredIndex < Index) {
         PredBefore = true;