Revert r173946. This breaks compilation of googletest with Clang

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174048 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Utils/ValueMapper.cpp b/lib/Transforms/Utils/ValueMapper.cpp
index b9e4ddf..a5e1643 100644
--- a/lib/Transforms/Utils/ValueMapper.cpp
+++ b/lib/Transforms/Utils/ValueMapper.cpp
@@ -63,23 +63,14 @@
     // Check all operands to see if any need to be remapped.
     for (unsigned i = 0, e = MD->getNumOperands(); i != e; ++i) {
       Value *OP = MD->getOperand(i);
-      if (OP == 0) continue;
-      Value *Mapped_OP = MapValue(OP, VM, Flags, TypeMapper);
-      // If Mapped_Op is null, we should use indentity map.
-      if (Mapped_OP == OP || Mapped_OP == 0) continue;
+      if (OP == 0 || MapValue(OP, VM, Flags, TypeMapper) == OP) continue;
 
       // Ok, at least one operand needs remapping.  
       SmallVector<Value*, 4> Elts;
       Elts.reserve(MD->getNumOperands());
       for (i = 0; i != e; ++i) {
         Value *Op = MD->getOperand(i);
-        if (Op == 0)
-          Elts.push_back(0);
-        else {
-          Value *Mapped_Op = MapValue(Op, VM, Flags, TypeMapper);
-          // If Mapped_Op is null, we should use indentity map.
-          Elts.push_back(Mapped_Op ? Mapped_Op : Op);
-        }
+        Elts.push_back(Op ? MapValue(Op, VM, Flags, TypeMapper) : 0);
       }
       MDNode *NewMD = MDNode::get(V->getContext(), Elts);
       Dummy->replaceAllUsesWith(NewMD);