ScheduleDAG: colorize the DOT graph and improve formatting.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173431 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/ScheduleDAGPrinter.cpp

@@ -41,6 +41,10 @@ namespace llvm {
       return true;
     }
 
+    static bool isNodeHidden(const SUnit *Node) {
+      return (Node->NumPreds > 10 || Node->NumSuccs > 10);
+    }
+
     static bool hasNodeAddressLabel(const SUnit *Node,
                                     const ScheduleDAG *Graph) {
       return true;