Merging r195670:
------------------------------------------------------------------------
r195670 | void | 2013-11-25 10:05:22 -0800 (Mon, 25 Nov 2013) | 5 lines

Unrevert r195599 with testcase fix.

I'm not sure how it was checking for the wrong values...
PR18023.

------------------------------------------------------------------------


git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_34@195672 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index c126a53..805cc9e 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -8692,6 +8692,11 @@
         Index = STn;
         break;
       } else if (LoadSDNode *Ldn = dyn_cast<LoadSDNode>(NextInChain)) {
+        if (Ldn->isVolatile()) {
+          Index = NULL;
+          break;
+        }
+
         // Save the load node for later. Continue the scan.
         AliasLoadNodes.push_back(Ldn);
         NextInChain = Ldn->getChain().getNode();