Add a comment for a nasty short term hack.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46610 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
index ac35b40..3873c33 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
@@ -741,6 +741,10 @@
       unsigned NumLabels = 0;
       MachineBasicBlock::iterator MBBI = BB->begin();
       while (MBBI != BB->end()) {
+        // FIXME: This is a nasty short term workaround. For now, we are
+        // assuming there are two debug labels at the beginning of the
+        // entry block: one for dbg_func_start, one for the first
+        // dbg_stoppoint before actual code.
         if (!MBBI->isDebugLabel() || ++NumLabels > 1)
           break;
         ++MBBI;