Add a marker for the graph root.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@19445 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp
index db094a0..4a70642 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp
@@ -32,6 +32,12 @@
     static std::string getNodeAttributes(const SDNode *N) {
       return "shape=Mrecord";
     }
+
+    static void addCustomGraphFeatures(SelectionDAG *G,
+                                       GraphWriter<SelectionDAG*> &GW) {
+      GW.emitSimpleNode(0, "plaintext=circle", "GraphRoot");
+      GW.emitEdge(0, -1, G->getRoot().Val, -1, "");
+    }
   };
 }