Fix last DOTGraphTraits problems in CompilationGraph.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90136 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp
index b4fe80c..c5adc50 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp
@@ -132,7 +132,7 @@
 
 std::string DOTGraphTraits<SelectionDAG*>::getNodeLabel(const SDNode *Node,
                                                         const SelectionDAG *G) {
-  DOTGraphTraits<SelectionDAG*>::getSimpleNodeLabel (Node, G);
+  return DOTGraphTraits<SelectionDAG*>::getSimpleNodeLabel (Node, G);
 }