diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 4dc106e..43e6b1b 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3814,14 +3814,8 @@
 
     MDNode *Variable = DI.getVariable();
     // Parameters are handled specially.
-    bool isParameter = false;
-    ConstantInt *CI = dyn_cast_or_null<ConstantInt>(Variable->getOperand(0));
-    if (CI) {
-      unsigned Val = CI->getZExtValue();
-      unsigned Tag = Val & ~LLVMDebugVersionMask;
-      if (Tag == dwarf::DW_TAG_arg_variable)
-        isParameter = true;
-    }
+    bool isParameter = 
+      DIVariable(Variable).getTag() == dwarf::DW_TAG_arg_variable;
     const Value *Address = DI.getAddress();
     if (!Address)
       return 0;