From: Evan Cheng <evan.cheng@apple.com>
Date: Fri, 1 Apr 2011 19:57:01 +0000 (+0000)
Subject: Add comments.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c249e4855883d7b799db61edc839cbfaff50ae81;p=oota-llvm.git

Add comments.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128730 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 94923530895..6785d6943e1 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4929,9 +4929,11 @@ void SelectionDAGBuilder::LowerCallTo(ImmutableCallSite CS, SDValue Callee,
                          &ReturnValues[0], ReturnValues.size()));
   }
 
-  // As a special case, a null chain means that a tail call has been emitted and
-  // the DAG root is already updated.
+  // Assign order to nodes here. If the call does not produce a result, it won't
+  // be mapped to a SDNode and visit() will not assign it an order number.
   if (!Result.second.getNode()) {
+    // As a special case, a null chain means that a tail call has been emitted and
+    // the DAG root is already updated.
     HasTailCall = true;
     ++SDNodeOrder;
     AssignOrderingToNode(DAG.getRoot().getNode());