Disallow null as a named metadata operand.
Make MDNode::destroy private.
Fix the one thing that used MDNode::destroy, outside of MDNode itself.

One should never delete or destroy an MDNode explicitly. MDNodes
implicitly go away when there are no references to them (implementation
details aside).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109028 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index 985c16c..64c2dfa 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -558,12 +558,8 @@
       Record.clear();
 
       // Write named metadata operands.
-      for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
-        if (NMD->getOperand(i))
-          Record.push_back(VE.getValueID(NMD->getOperand(i)));
-        else
-          Record.push_back(~0U);
-      }
+      for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
+        Record.push_back(VE.getValueID(NMD->getOperand(i)));
       Stream.EmitRecord(bitc::METADATA_NAMED_NODE, Record, 0);
       Record.clear();
     }