Move private classes into anonymous namespaces

NFC.

llvm-svn: 232944
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 7021471..3555479 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -9984,6 +9984,7 @@
   return SDValue();
 }
 
+namespace {
 /// Helper struct to parse and store a memory address as base + index + offset.
 /// We ignore sign extensions when it is safe to do so.
 /// The following two expressions are not equivalent. To differentiate we need
@@ -10071,6 +10072,7 @@
     return BaseIndexOffset(Base, Index, Off, IsIndexSignExt);
   }
 };
+} // namespace
 
 bool DAGCombiner::MergeStoresOfConstantsOrVecElts(
                   SmallVectorImpl<MemOpLink> &StoreNodes, EVT MemVT,