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

7 files changed, 10 insertions, 31 deletions

diff --git a/lib/Analysis/DebugInfo.cpp b/lib/Analysis/DebugInfo.cpp
index ca6c2e6d72..277edefe7b 100644
--- a/lib/Analysis/DebugInfo.cpp
+++ b/lib/Analysis/DebugInfo.cpp
@@ -233,8 +233,7 @@ unsigned DIArray::getNumElements() const {
 }
 
 /// replaceAllUsesWith - Replace all uses of debug info referenced by
-/// this descriptor. After this completes, the current debug info value
-/// is erased.
+/// this descriptor.
 void DIDerivedType::replaceAllUsesWith(DIDescriptor &D) {
   if (!DbgNode)
     return;
@@ -249,7 +248,6 @@ void DIDerivedType::replaceAllUsesWith(DIDescriptor &D) {
     const MDNode *DN = D;
     const Value *V = cast_or_null<Value>(DN);
     Node->replaceAllUsesWith(const_cast<Value*>(V));
-    Node->destroy();
   }
 }
 
@@ -1385,7 +1383,7 @@ static Value *findDbgGlobalDeclare(GlobalVariable *V) {
     return 0;
 
   for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
-    DIDescriptor DIG(cast_or_null<MDNode>(NMD->getOperand(i)));
+    DIDescriptor DIG(cast<MDNode>(NMD->getOperand(i)));
     if (!DIG.isGlobalVariable())
       continue;
     if (DIGlobalVariable(DIG).getGlobal() == V)
diff --git a/lib/AsmParser/LLParser.cpp b/lib/AsmParser/LLParser.cpp
index 221b994db5..06229d78e2 100644
--- a/lib/AsmParser/LLParser.cpp
+++ b/lib/AsmParser/LLParser.cpp
@@ -546,12 +546,6 @@ bool LLParser::ParseNamedMetadata() {
   SmallVector<MDNode *, 8> Elts;
   if (Lex.getKind() != lltok::rbrace)
     do {
-      // Null is a special case since it is typeless.
-      if (EatIfPresent(lltok::kw_null)) {
-        Elts.push_back(0);
-        continue;
-      }
-
       if (ParseToken(lltok::exclaim, "Expected '!' here"))
         return true;
     
diff --git a/lib/Bitcode/Reader/BitcodeReader.cpp b/lib/Bitcode/Reader/BitcodeReader.cpp
index f486b51cae..7d82321afc 100644
--- a/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -803,10 +803,6 @@ bool BitcodeReader::ParseMetadata() {
       unsigned Size = Record.size();
       SmallVector<MDNode *, 8> Elts;
       for (unsigned i = 0; i != Size; ++i) {
-        if (Record[i] == ~0U) {
-          Elts.push_back(NULL);
-          continue;
-        }
         MDNode *MD = dyn_cast<MDNode>(MDValueList.getValueFwdRef(Record[i]));
         if (MD == 0)
           return Error("Malformed metadata record");
diff --git a/lib/Bitcode/Writer/BitcodeWriter.cpp b/lib/Bitcode/Writer/BitcodeWriter.cpp
index 985c16c783..64c2dfaee8 100644
--- a/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -558,12 +558,8 @@ static void WriteModuleMetadata(const ValueEnumerator &VE,
       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();
     }
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index a1f646a425..5f7d052ec0 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -2319,7 +2319,7 @@ DwarfDebug::collectVariableInfo(const MachineFunction *MF,
       M->getNamedMetadata(Twine("llvm.dbg.lv.", 
                                 getRealLinkageName(F->getName())))) {
     for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
-      DIVariable DV(cast_or_null<MDNode>(NMD->getOperand(i)));
+      DIVariable DV(cast<MDNode>(NMD->getOperand(i)));
       if (!DV || !Processed.insert(DV))
         continue;
       DbgScope *Scope = DbgScopeMap.lookup(DV.getContext());
@@ -2783,7 +2783,7 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
             M->getNamedMetadata(Twine("llvm.dbg.lv.", 
                                       getRealLinkageName(FName)))) {
           for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
-          DIVariable DV(cast_or_null<MDNode>(NMD->getOperand(i)));
+          DIVariable DV(cast<MDNode>(NMD->getOperand(i)));
           if (!DV || !ProcessedVars.insert(DV))
             continue;
           DbgScope *Scope = AbstractScopes.lookup(DV.getContext());
diff --git a/lib/VMCore/AsmWriter.cpp b/lib/VMCore/AsmWriter.cpp
index c371ab97cd..7d51be1150 100644
--- a/lib/VMCore/AsmWriter.cpp
+++ b/lib/VMCore/AsmWriter.cpp
@@ -638,10 +638,8 @@ void SlotTracker::processModule() {
          I = TheModule->named_metadata_begin(),
          E = TheModule->named_metadata_end(); I != E; ++I) {
     const NamedMDNode *NMD = I;
-    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
-      if (MDNode *MD = NMD->getOperand(i))
-        CreateMetadataSlot(MD);
-    }
+    for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i)
+      CreateMetadataSlot(NMD->getOperand(i));
   }
 
   // Add all the unnamed functions to the table.
@@ -1424,10 +1422,7 @@ void AssemblyWriter::printNamedMDNode(const NamedMDNode *NMD) {
   Out << "!" << NMD->getName() << " = !{";
   for (unsigned i = 0, e = NMD->getNumOperands(); i != e; ++i) {
     if (i) Out << ", ";
-    if (MDNode *MD = NMD->getOperand(i))
-      Out << '!' << Machine.getMetadataSlot(MD);
-    else
-      Out << "null";
+    Out << '!' << Machine.getMetadataSlot(NMD->getOperand(i));
   }
   Out << "}\n";
 }
diff --git a/lib/VMCore/Metadata.cpp b/lib/VMCore/Metadata.cpp
index a89cffd8e0..cc4a68ec41 100644
--- a/lib/VMCore/Metadata.cpp
+++ b/lib/VMCore/Metadata.cpp
@@ -389,7 +389,7 @@ unsigned NamedMDNode::getNumOperands() const {
 /// getOperand - Return specified operand.
 MDNode *NamedMDNode::getOperand(unsigned i) const {
   assert(i < getNumOperands() && "Invalid Operand number!");
-  return dyn_cast_or_null<MDNode>(&*getNMDOps(Operands)[i]);
+  return dyn_cast<MDNode>(&*getNMDOps(Operands)[i]);
 }
 
 /// addOperand - Add metadata Operand.