Small PostDominatorTree improvements

 * Do not SEGFAULT if tree entryNode() is NULL
 * Print function names in dotty printer

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90130 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/DomPrinter.cpp b/lib/Analysis/DomPrinter.cpp
index f1b44d0..ebfba7e 100644
--- a/lib/Analysis/DomPrinter.cpp
+++ b/lib/Analysis/DomPrinter.cpp
@@ -85,9 +85,11 @@
 
   virtual bool runOnFunction(Function &F) {
     Analysis *Graph;
-
+    std::string Title, GraphName;
     Graph = &getAnalysis<Analysis>();
-    ViewGraph(Graph, Name, OnlyBBS);
+    GraphName = DOTGraphTraits<Analysis*>::getGraphName(Graph);
+    Title = GraphName + " for '" + F.getNameStr() + "' function";
+    ViewGraph(Graph, Name, OnlyBBS, Title);
 
     return false;
   }
@@ -163,8 +165,12 @@
     raw_fd_ostream File(Filename.c_str(), ErrorInfo);
     Graph = &getAnalysis<Analysis>();
 
+    std::string Title, GraphName;
+    GraphName = DOTGraphTraits<Analysis*>::getGraphName(Graph);
+    Title = GraphName + " for '" + F.getNameStr() + "' function";
+
     if (ErrorInfo.empty())
-      WriteGraph(File, Graph, OnlyBBS);
+      WriteGraph(File, Graph, OnlyBBS, Name, Title);
     else
       errs() << "  error opening file for writing!";
     errs() << "\n";