Eliminate some unused variable compile time warnings.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59952 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index f55bdec..41aa044 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -1212,9 +1212,11 @@
 }
 
 SDValue SelectionDAG::getMemOperand(const MachineMemOperand &MO) {
+#ifndef NDEBUG
   const Value *v = MO.getValue();
   assert((!v || isa<PointerType>(v->getType())) &&
          "SrcValue is not a pointer?");
+#endif
 
   FoldingSetNodeID ID;
   AddNodeIDNode(ID, ISD::MEMOPERAND, getVTList(MVT::Other), 0, 0);