[DomPrinter] Add a way to programmatically dump a dot representation.

Differential Revision:  https://reviews.llvm.org/D32145

llvm-svn: 301205

llvm/include/llvm/IR/Dominators.h

@@ -157,6 +157,10 @@ public:
   /// This should only be used for debugging as it aborts the program if the
   /// verification fails.
   void verifyDomTree() const;
+
+  // Pop up a GraphViz/gv window with the Dominator Tree rendered using `dot`.
+  void viewGraph(const Twine &Name, const Twine &Title);
+  void viewGraph();
 };
 
 //===-------------------------------------

llvm/lib/Analysis/DomPrinter.cpp

@@ -80,6 +80,22 @@ struct DOTGraphTraits<PostDominatorTree*>
 };
 }
 
+void DominatorTree::viewGraph(const Twine &Name, const Twine &Title) {
+#ifndef NDEBUG
+  ViewGraph(this, Name, false, Title);
+#else
+  errs() << "DomTree dump not available, build with DEBUG\n";
+#endif  // NDEBUG
+}
+
+void DominatorTree::viewGraph() {
+#ifndef NDEBUG
+  this->viewGraph("domtree", "Dominator Tree for function");
+#else
+  errs() << "DomTree dump not available, build with DEBUG\n";
+#endif  // NDEBUG
+}
+
 namespace {
 struct DominatorTreeWrapperPassAnalysisGraphTraits {
   static DominatorTree *getGraph(DominatorTreeWrapperPass *DTWP) {