[llvm] r187316 - Update the comment

[Nadav Rotem]

Author: nadav
Date: Sat Jul 27 18:28:47 2013
New Revision: 187316

URL: http://llvm.org/viewvc/llvm-project?rev=187316&view=rev
Log:
Update the comment

Modified:
    llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp

Modified: llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp?rev=187316&r1=187315&r2=187316&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp (original)
+++ llvm/trunk/lib/Transforms/Vectorize/SLPVectorizer.cpp Sat Jul 27 18:28:47 2013
@@ -900,6 +900,7 @@ int BoUpSLP::getTreeCost() {
 
   // Don't vectorize tiny trees. Small load/store chains or consecutive stores
   // of constants will be vectoried in SelectionDAG in MergeConsecutiveStores.
+  // The SelectionDAG vectorizer can only handle pairs (trees of height = 2).
   if (VectorizableTree.size() < 3) {
     if (!VectorizableTree.size()) {
       assert(!ExternalUses.size() && "We should not have any external users");