Fix an obsolete top-level comment.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53481 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
index b12e68e..c34abca 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAG.cpp
@@ -7,9 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This implements a simple two pass scheduler.  The first pass attempts to push
-// backward any lengthy instructions and critical paths.  The second pass packs
-// instructions into semi-optimal time slots.
+// This implements the ScheduleDAG class, which is a base class used by
+// scheduling implementation classes.
 //
 //===----------------------------------------------------------------------===//