Comment: try to clarify loop iteration order.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186774 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/LoopPass.cpp b/lib/Analysis/LoopPass.cpp
index 1540112..acf2ba6 100644
--- a/lib/Analysis/LoopPass.cpp
+++ b/lib/Analysis/LoopPass.cpp
@@ -188,6 +188,10 @@
// advantage in deleting uses in a later loop before optimizing the
// definitions in an earlier loop. If we find a clear reason to process in
// forward order, then a forward variant of LoopPassManager should be created.
+ //
+ // Note that LoopInfo::iterator visits loops in reverse program
+ // order. Here, reverse_iterator gives us a forward order, and the LoopQueue
+ // reverses the order a third time by popping from the back.
for (LoopInfo::reverse_iterator I = LI->rbegin(), E = LI->rend(); I != E; ++I)
addLoopIntoQueue(*I, LQ);