Make it simplier to dump DAGs while in DAGCombiner.  Remove a nasty optimization.

llvm-svn: 31009
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 5a0f5b1..9faf703 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -2684,7 +2684,7 @@
       DumpNodes(Nodes[i], 2, this);
   }
 
-  DumpNodes(getRoot().Val, 2, this);
+  if (getRoot().Val) DumpNodes(getRoot().Val, 2, this);
 
   std::cerr << "\n\n";
 }