Use an otherwise unused variable.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@160798 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/MachineTraceMetrics.cpp b/lib/CodeGen/MachineTraceMetrics.cpp
index b302101..557d473 100644
--- a/lib/CodeGen/MachineTraceMetrics.cpp
+++ b/lib/CodeGen/MachineTraceMetrics.cpp
@@ -384,7 +384,7 @@
     DEBUG(dbgs() << "  succ for BB#" << I->getNumber() << ": ");
     TraceBlockInfo &TBI = BlockInfo[I->getNumber()];
     // All the successors have been visited, pick the preferred one.
-    BlockInfo[I->getNumber()].Succ = pickTraceSucc(*I);
+    TBI.Succ = pickTraceSucc(*I);
     DEBUG({
       if (TBI.Pred)
         dbgs() << "BB#" << TBI.Succ->getNumber() << '\n';