Index: lib/Transforms/Utils/LoopUnroll.cpp
===================================================================
--- lib/Transforms/Utils/LoopUnroll.cpp
+++ lib/Transforms/Utils/LoopUnroll.cpp
@@ -185,7 +185,9 @@
 /// terminates LatchBlock in order to remove unnecesssary instances of the
 /// test. In other words, control may exit the loop prior to TripCount
 /// iterations via an early branch, but control may not exit the loop from the
-/// LatchBlock's terminator prior to TripCount iterations.
+/// LatchBlock's terminator prior to TripCount iterations.  Parameter TripCount
+/// may contain the exact number or the upper bound.  Which one is used is 
+/// determined by the Parameter PreserveCondBr (see below).
 ///
 /// PreserveCondBr indicates whether the conditional branch of the LatchBlock
 /// needs to be preserved.  It is needed when we use trip count upper bound to