From 639cdc210b86302bfa03e2a88266ef0d4aba102c Mon Sep 17 00:00:00 2001
From: Dan Gohman <gohman@apple.com>
Date: Mon, 21 Apr 2008 20:07:30 +0000
Subject: [PATCH] Fix an out-of-bounds access in -view-sunit-dags in the case
 of an empty ScheduleDAG.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50054 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp
index b07b86eb949..904638d4f7a 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGPrinter.cpp
@@ -301,7 +301,8 @@ namespace llvm {
     static void addCustomGraphFeatures(ScheduleDAG *G,
                                        GraphWriter<ScheduleDAG*> &GW) {
       GW.emitSimpleNode(0, "plaintext=circle", "GraphRoot");
-      if (G->DAG.getRoot().Val)
+      if (G->DAG.getRoot().Val &&
+          G->SUnitMap.find(G->DAG.getRoot().Val) != G->SUnitMap.end())
         GW.emitEdge(0, -1, G->SUnitMap[G->DAG.getRoot().Val].front(), -1, "");
     }
   };