Eliminate some unused variable compile time warnings.

llvm-svn: 59952
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index f55bdec9..41aa044 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/llvm/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);