Cleanup in preparation for misched: Move DAG visualization logic.

Soon, ScheduleDAG will not refer to the BB.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@152177 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp
index c0ccdb3..bad6286 100644
--- a/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -808,6 +808,12 @@
   return oss.str();
 }
 
+/// Return the basic block label. It is not necessarilly unique because a block
+/// contains multiple scheduling regions. But it is fine for visualization.
+std::string ScheduleDAGInstrs::getDAGName() const {
+  return "dag." + BB->getFullName();
+}
+
 // EmitSchedule - Emit the machine code in scheduled order.
 MachineBasicBlock *ScheduleDAGInstrs::EmitSchedule() {
   Begin = InsertPos;