1 files changed, 10 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
index c4dba414416..bf77d4c7f73 100644
--- a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
@@ -17,8 +17,17 @@
 #include "llvm/CodeGen/SelectionDAG.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Support/CommandLine.h"
 using namespace llvm;
 
+#ifndef _NDEBUG
+static cl::opt<bool>
+ViewDAGs("view-sched-dags", cl::Hidden,
+         cl::desc("Pop up a window to show sched dags as they are processed"));
+#else
+static const bool ViewDAGS = 0;
+#endif
+
 namespace {
   class SimpleSched {
     SelectionDAG &DAG;
@@ -112,5 +121,6 @@ unsigned SimpleSched::Emit(SDOperand Op) {
 /// Pick a safe ordering and emit instructions for each target node in the
 /// graph.
 void SelectionDAGISel::ScheduleAndEmitDAG(SelectionDAG &SD) {
+  if (ViewDAGs) SD.viewGraph();
   SimpleSched(SD, BB).Run();  
 }