diff --git a/include/llvm/Analysis/DebugInfo.h b/include/llvm/Analysis/DebugInfo.h
index 14c3e1bb1cf..f105c20ff20 100644
--- a/include/llvm/Analysis/DebugInfo.h
+++ b/include/llvm/Analysis/DebugInfo.h
@@ -67,7 +67,7 @@ namespace llvm {
     explicit DIDescriptor() : DbgNode(0) {}
     explicit DIDescriptor(MDNode *N) : DbgNode(N) {}
 
-    bool Verify() const { return DbgNode != 0; }
+    bool isNull() const { return DbgNode == 0; }
 
     MDNode *getNode() const { return DbgNode; }
 
@@ -246,9 +246,7 @@ namespace llvm {
     bool isArtificial() const {
       return (getFlags() & FlagArtificial) != 0;
     }
-    bool isValid() const {
-      return DbgNode && (isBasicType() || isDerivedType() || isCompositeType());
-    }
+
     /// dump - print type.
     void dump() const;
   };
@@ -362,7 +360,7 @@ namespace llvm {
     /// DIType or as DICompositeType.
     StringRef getReturnTypeName() const {
       DICompositeType DCT(getFieldAs<DICompositeType>(8));
-      if (DCT.Verify()) {
+      if (!DCT.isNull()) {
         DIArray A = DCT.getTypeArray();
         DIType T(A.getElement(0).getNode());
         return T.getName();
@@ -496,7 +494,6 @@ namespace llvm {
     DILocation getOrigLocation() const { return getFieldAs<DILocation>(3); }
     StringRef getFilename() const    { return getScope().getFilename(); }
     StringRef getDirectory() const   { return getScope().getDirectory(); }
-    bool Verify() const;
   };
 
   /// DIFactory - This object assists with the construction of the various
diff --git a/lib/Analysis/DebugInfo.cpp b/lib/Analysis/DebugInfo.cpp
index 98082ffb18f..5cfe666b15e 100644
--- a/lib/Analysis/DebugInfo.cpp
+++ b/lib/Analysis/DebugInfo.cpp
@@ -132,12 +132,13 @@ unsigned DIVariable::getNumAddrElements() const {
 /// isBasicType - Return true if the specified tag is legal for
 /// DIBasicType.
 bool DIDescriptor::isBasicType() const {
-  return DbgNode && getTag() == dwarf::DW_TAG_base_type;
+  assert(!isNull() && "Invalid descriptor!");
+  return getTag() == dwarf::DW_TAG_base_type;
 }
 
 /// isDerivedType - Return true if the specified tag is legal for DIDerivedType.
 bool DIDescriptor::isDerivedType() const {
-  if (!DbgNode) return false;
+  assert(!isNull() && "Invalid descriptor!");
   switch (getTag()) {
   case dwarf::DW_TAG_typedef:
   case dwarf::DW_TAG_pointer_type:
@@ -157,7 +158,7 @@ bool DIDescriptor::isDerivedType() const {
 /// isCompositeType - Return true if the specified tag is legal for
 /// DICompositeType.
 bool DIDescriptor::isCompositeType() const {
-  if (!DbgNode) return false;
+  assert(!isNull() && "Invalid descriptor!");
   switch (getTag()) {
   case dwarf::DW_TAG_array_type:
   case dwarf::DW_TAG_structure_type:
@@ -174,7 +175,7 @@ bool DIDescriptor::isCompositeType() const {
 
 /// isVariable - Return true if the specified tag is legal for DIVariable.
 bool DIDescriptor::isVariable() const {
-  if (!DbgNode) return false;
+  assert(!isNull() && "Invalid descriptor!");
   switch (getTag()) {
   case dwarf::DW_TAG_auto_variable:
   case dwarf::DW_TAG_arg_variable:
@@ -193,13 +194,15 @@ bool DIDescriptor::isType() const {
 /// isSubprogram - Return true if the specified tag is legal for
 /// DISubprogram.
 bool DIDescriptor::isSubprogram() const {
-  return DbgNode && getTag() == dwarf::DW_TAG_subprogram;
+  assert(!isNull() && "Invalid descriptor!");
+  return getTag() == dwarf::DW_TAG_subprogram;
 }
 
 /// isGlobalVariable - Return true if the specified tag is legal for
 /// DIGlobalVariable.
 bool DIDescriptor::isGlobalVariable() const {
-  return DbgNode && getTag() == dwarf::DW_TAG_variable;
+  assert(!isNull() && "Invalid descriptor!");
+  return getTag() == dwarf::DW_TAG_variable;
 }
 
 /// isGlobal - Return true if the specified tag is legal for DIGlobal.
@@ -210,7 +213,7 @@ bool DIDescriptor::isGlobal() const {
 /// isScope - Return true if the specified tag is one of the scope
 /// related tag.
 bool DIDescriptor::isScope() const {
-  if (!DbgNode) return false;
+  assert(!isNull() && "Invalid descriptor!");
   switch (getTag()) {
   case dwarf::DW_TAG_compile_unit:
   case dwarf::DW_TAG_lexical_block:
@@ -225,27 +228,32 @@ bool DIDescriptor::isScope() const {
 
 /// isCompileUnit - Return true if the specified tag is DW_TAG_compile_unit.
 bool DIDescriptor::isCompileUnit() const {
-  return DbgNode && getTag() == dwarf::DW_TAG_compile_unit;
+  assert(!isNull() && "Invalid descriptor!");
+  return getTag() == dwarf::DW_TAG_compile_unit;
 }
 
 /// isNameSpace - Return true if the specified tag is DW_TAG_namespace.
 bool DIDescriptor::isNameSpace() const {
-  return DbgNode && getTag() == dwarf::DW_TAG_namespace;
+  assert(!isNull() && "Invalid descriptor!");
+  return getTag() == dwarf::DW_TAG_namespace;
 }
 
 /// isLexicalBlock - Return true if the specified tag is DW_TAG_lexical_block.
 bool DIDescriptor::isLexicalBlock() const {
-  return DbgNode && getTag() == dwarf::DW_TAG_lexical_block;
+  assert(!isNull() && "Invalid descriptor!");
+  return getTag() == dwarf::DW_TAG_lexical_block;
 }
 
 /// isSubrange - Return true if the specified tag is DW_TAG_subrange_type.
 bool DIDescriptor::isSubrange() const {
-  return DbgNode && getTag() == dwarf::DW_TAG_subrange_type;
+  assert(!isNull() && "Invalid descriptor!");
+  return getTag() == dwarf::DW_TAG_subrange_type;
 }
 
 /// isEnumerator - Return true if the specified tag is DW_TAG_enumerator.
 bool DIDescriptor::isEnumerator() const {
-  return DbgNode && getTag() == dwarf::DW_TAG_enumerator;
+  assert(!isNull() && "Invalid descriptor!");
+  return getTag() == dwarf::DW_TAG_enumerator;
 }
 
 //===----------------------------------------------------------------------===//
@@ -260,8 +268,7 @@ DIType::DIType(MDNode *N) : DIDescriptor(N) {
 }
 
 unsigned DIArray::getNumElements() const {
-  if (!DbgNode)
-    return 0;
+  assert(DbgNode && "Invalid DIArray");
   return DbgNode->getNumOperands();
 }
 
@@ -269,9 +276,11 @@ unsigned DIArray::getNumElements() const {
 /// this descriptor. After this completes, the current debug info value
 /// is erased.
 void DIDerivedType::replaceAllUsesWith(DIDescriptor &D) {
-  if (!DbgNode)
+  if (isNull())
     return;
 
+  assert(!D.isNull() && "Can not replace with null");
+
   // Since we use a TrackingVH for the node, its easy for clients to manufacture
   // legitimate situations where they want to replaceAllUsesWith() on something
   // which, due to uniquing, has merged with the source. We shield clients from
@@ -286,7 +295,7 @@ void DIDerivedType::replaceAllUsesWith(DIDescriptor &D) {
 
 /// Verify - Verify that a compile unit is well formed.
 bool DICompileUnit::Verify() const {
-  if (!DbgNode)
+  if (isNull())
     return false;
   StringRef N = getFilename();
   if (N.empty())
@@ -297,36 +306,36 @@ bool DICompileUnit::Verify() const {
 
 /// Verify - Verify that a type descriptor is well formed.
 bool DIType::Verify() const {
-  if (!DbgNode)
+  if (isNull())
     return false;
-  if (!getContext().Verify())
+  if (getContext().isNull())
     return false;
 
   DICompileUnit CU = getCompileUnit();
-  if (!CU.Verify())
+  if (!CU.isNull() && !CU.Verify())
     return false;
   return true;
 }
 
 /// Verify - Verify that a composite type descriptor is well formed.
 bool DICompositeType::Verify() const {
-  if (!DbgNode)
+  if (isNull())
     return false;
-  if (!getContext().Verify())
+  if (getContext().isNull())
     return false;
 
   DICompileUnit CU = getCompileUnit();
-  if (!CU.Verify())
+  if (!CU.isNull() && !CU.Verify())
     return false;
   return true;
 }
 
 /// Verify - Verify that a subprogram descriptor is well formed.
 bool DISubprogram::Verify() const {
-  if (!DbgNode)
+  if (isNull())
     return false;
 
-  if (!getContext().Verify())
+  if (getContext().isNull())
     return false;
 
   DICompileUnit CU = getCompileUnit();
@@ -334,24 +343,24 @@ bool DISubprogram::Verify() const {
     return false;
 
   DICompositeType Ty = getType();
-  if (!Ty.Verify())
+  if (!Ty.isNull() && !Ty.Verify())
     return false;
   return true;
 }
 
 /// Verify - Verify that a global variable descriptor is well formed.
 bool DIGlobalVariable::Verify() const {
-  if (!DbgNode)
+  if (isNull())
     return false;
 
   if (getDisplayName().empty())
     return false;
 
-  if (!getContext().Verify())
+  if (getContext().isNull())
     return false;
 
   DICompileUnit CU = getCompileUnit();
-  if (!CU.Verify())
+  if (!CU.isNull() && !CU.Verify())
     return false;
 
   DIType Ty = getType();
@@ -366,10 +375,10 @@ bool DIGlobalVariable::Verify() const {
 
 /// Verify - Verify that a variable descriptor is well formed.
 bool DIVariable::Verify() const {
-  if (!DbgNode)
+  if (isNull())
     return false;
 
-  if (!getContext().Verify())
+  if (getContext().isNull())
     return false;
 
   DIType Ty = getType();
@@ -379,14 +388,6 @@ bool DIVariable::Verify() const {
   return true;
 }
 
-/// Verify - Verify that a location descriptor is well formed.
-bool DILocation::Verify() const {
-  if (!DbgNode)
-    return false;
-  
-  return DbgNode->getNumOperands() == 4;
-}
-
 /// getOriginalTypeSize - If this type is derived from a base type then
 /// return base type size.
 uint64_t DIDerivedType::getOriginalTypeSize() const {
@@ -397,7 +398,7 @@ uint64_t DIDerivedType::getOriginalTypeSize() const {
     DIType BaseType = getTypeDerivedFrom();
     // If this type is not derived from any type then take conservative 
     // approach.
-    if (!BaseType.isValid())
+    if (BaseType.isNull())
       return getSizeInBits();
     if (BaseType.isDerivedType())
       return DIDerivedType(BaseType.getNode()).getOriginalTypeSize();
@@ -467,7 +468,7 @@ void DICompileUnit::dump() const {
 
 /// dump - Print type.
 void DIType::dump() const {
-  if (!DbgNode) return;
+  if (isNull()) return;
 
   StringRef Res = getName();
   if (!Res.empty())
@@ -520,6 +521,8 @@ void DIDerivedType::dump() const {
 /// dump - Print composite type.
 void DICompositeType::dump() const {
   DIArray A = getTypeArray();
+  if (A.isNull())
+    return;
   dbgs() << " [" << A.getNumElements() << " elements]";
 }
 
@@ -1152,8 +1155,9 @@ void DebugInfoFinder::processModule(Module &M) {
 
 /// processLocation - Process DILocation.
 void DebugInfoFinder::processLocation(DILocation Loc) {
-  if (!Loc.Verify()) return;
-  DIDescriptor S(Loc.getScope().getNode());
+  if (Loc.isNull()) return;
+  DIScope S(Loc.getScope().getNode());
+  if (S.isNull()) return;
   if (S.isCompileUnit())
     addCompileUnit(DICompileUnit(S.getNode()));
   else if (S.isSubprogram())
@@ -1173,21 +1177,26 @@ void DebugInfoFinder::processType(DIType DT) {
     DICompositeType DCT(DT.getNode());
     processType(DCT.getTypeDerivedFrom());
     DIArray DA = DCT.getTypeArray();
-    for (unsigned i = 0, e = DA.getNumElements(); i != e; ++i) {
-      DIDescriptor D = DA.getElement(i);
-      if (D.isType())
-        processType(DIType(D.getNode()));
-      else if (D.isSubprogram())
-        processSubprogram(DISubprogram(D.getNode()));
-    }
+    if (!DA.isNull())
+      for (unsigned i = 0, e = DA.getNumElements(); i != e; ++i) {
+        DIDescriptor D = DA.getElement(i);
+        DIType TyE = DIType(D.getNode());
+        if (!TyE.isNull())
+          processType(TyE);
+        else
+          processSubprogram(DISubprogram(D.getNode()));
+      }
   } else if (DT.isDerivedType()) {
     DIDerivedType DDT(DT.getNode());
-    processType(DDT.getTypeDerivedFrom());
+    if (!DDT.isNull())
+      processType(DDT.getTypeDerivedFrom());
   }
 }
 
 /// processLexicalBlock
 void DebugInfoFinder::processLexicalBlock(DILexicalBlock LB) {
+  if (LB.isNull())
+    return;
   DIScope Context = LB.getContext();
   if (Context.isLexicalBlock())
     return processLexicalBlock(DILexicalBlock(Context.getNode()));
@@ -1197,6 +1206,8 @@ void DebugInfoFinder::processLexicalBlock(DILexicalBlock LB) {
 
 /// processSubprogram - Process DISubprogram.
 void DebugInfoFinder::processSubprogram(DISubprogram SP) {
+  if (SP.isNull())
+    return;
   if (!addSubprogram(SP))
     return;
   addCompileUnit(SP.getCompileUnit());
@@ -1205,23 +1216,20 @@ void DebugInfoFinder::processSubprogram(DISubprogram SP) {
 
 /// processDeclare - Process DbgDeclareInst.
 void DebugInfoFinder::processDeclare(DbgDeclareInst *DDI) {
-  MDNode *N = dyn_cast<MDNode>(DDI->getVariable());
-  if (!N) return;
-
-  DIDescriptor DV(N);
-  if (!DV.isVariable())
+  DIVariable DV(cast<MDNode>(DDI->getVariable()));
+  if (DV.isNull())
     return;
 
   if (!NodesSeen.insert(DV.getNode()))
     return;
 
-  addCompileUnit(DIVariable(N).getCompileUnit());
-  processType(DIVariable(N).getType());
+  addCompileUnit(DV.getCompileUnit());
+  processType(DV.getType());
 }
 
 /// addType - Add type into Tys.
 bool DebugInfoFinder::addType(DIType DT) {
-  if (!DT.isValid())
+  if (DT.isNull())
     return false;
 
   if (!NodesSeen.insert(DT.getNode()))
@@ -1233,7 +1241,7 @@ bool DebugInfoFinder::addType(DIType DT) {
 
 /// addCompileUnit - Add compile unit into CUs.
 bool DebugInfoFinder::addCompileUnit(DICompileUnit CU) {
-  if (!CU.Verify())
+  if (CU.isNull())
     return false;
 
   if (!NodesSeen.insert(CU.getNode()))
@@ -1245,7 +1253,7 @@ bool DebugInfoFinder::addCompileUnit(DICompileUnit CU) {
 
 /// addGlobalVariable - Add global variable into GVs.
 bool DebugInfoFinder::addGlobalVariable(DIGlobalVariable DIG) {
-  if (!DIDescriptor(DIG.getNode()).isGlobalVariable())
+  if (DIG.isNull())
     return false;
 
   if (!NodesSeen.insert(DIG.getNode()))
@@ -1257,7 +1265,7 @@ bool DebugInfoFinder::addGlobalVariable(DIGlobalVariable DIG) {
 
 // addSubprogram - Add subprgoram into SPs.
 bool DebugInfoFinder::addSubprogram(DISubprogram SP) {
-  if (!DIDescriptor(SP.getNode()).isSubprogram())
+  if (SP.isNull())
     return false;
 
   if (!NodesSeen.insert(SP.getNode()))
@@ -1275,10 +1283,10 @@ 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)));
-    if (!DIG.isGlobalVariable())
+    DIGlobalVariable DIG(cast_or_null<MDNode>(NMD->getOperand(i)));
+    if (DIG.isNull())
       continue;
-    if (DIGlobalVariable(DIG.getNode()).getGlobal() == V)
+    if (DIG.getGlobal() == V)
       return DIG.getNode();
   }
   return 0;
@@ -1370,6 +1378,12 @@ DebugLoc llvm::ExtractDebugLocation(DILocation &Loc,
 /// getDISubprogram - Find subprogram that is enclosing this scope.
 DISubprogram llvm::getDISubprogram(MDNode *Scope) {
   DIDescriptor D(Scope);
+  if (D.isNull())
+    return DISubprogram();
+  
+  if (D.isCompileUnit())
+    return DISubprogram();
+  
   if (D.isSubprogram())
     return DISubprogram(Scope);
   
@@ -1381,6 +1395,9 @@ DISubprogram llvm::getDISubprogram(MDNode *Scope) {
 
 /// getDICompositeType - Find underlying composite type.
 DICompositeType llvm::getDICompositeType(DIType T) {
+  if (T.isNull())
+    return DICompositeType();
+  
   if (T.isCompositeType())
     return DICompositeType(T.getNode());
   
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index c0d92ffbbbc..bd2b1b61971 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -335,7 +335,7 @@ static void EmitComments(const MachineInstr &MI, raw_ostream &CommentOS) {
     // Print source line info.
     DIScope Scope = DLT.getScope();
     // Omit the directory, because it's likely to be long and uninteresting.
-    if (Scope.Verify())
+    if (!Scope.isNull())
       CommentOS << Scope.getFilename();
     else
       CommentOS << "<unknown>";
@@ -1287,7 +1287,7 @@ void AsmPrinter::processDebugLoc(const MachineInstr *MI,
   if (DL.isUnknown())
     return;
   DILocation CurDLT = MF->getDILocation(DL);
-  if (!CurDLT.getScope().Verify())
+  if (CurDLT.getScope().isNull())
     return;
 
   if (!BeforePrintingInsn) {
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index cfa84c40cb2..5ad1e5ea050 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -413,7 +413,7 @@ void DwarfDebug::addBlock(DIE *Die, unsigned Attribute, unsigned Form,
 /// entry.
 void DwarfDebug::addSourceLine(DIE *Die, const DIVariable *V) {
   // If there is no compile unit specified, don't add a line #.
-  if (!V->getCompileUnit().Verify())
+  if (V->getCompileUnit().isNull())
     return;
 
   unsigned Line = V->getLineNumber();
@@ -427,7 +427,7 @@ void DwarfDebug::addSourceLine(DIE *Die, const DIVariable *V) {
 /// entry.
 void DwarfDebug::addSourceLine(DIE *Die, const DIGlobal *G) {
   // If there is no compile unit specified, don't add a line #.
-  if (!G->getCompileUnit().Verify())
+  if (G->getCompileUnit().isNull())
     return;
 
   unsigned Line = G->getLineNumber();
@@ -441,7 +441,7 @@ void DwarfDebug::addSourceLine(DIE *Die, const DIGlobal *G) {
 /// entry.
 void DwarfDebug::addSourceLine(DIE *Die, const DISubprogram *SP) {
   // If there is no compile unit specified, don't add a line #.
-  if (!SP->getCompileUnit().Verify())
+  if (SP->getCompileUnit().isNull())
     return;
   // If the line number is 0, don't add it.
   if (SP->getLineNumber() == 0)
@@ -460,7 +460,7 @@ void DwarfDebug::addSourceLine(DIE *Die, const DISubprogram *SP) {
 void DwarfDebug::addSourceLine(DIE *Die, const DIType *Ty) {
   // If there is no compile unit specified, don't add a line #.
   DICompileUnit CU = Ty->getCompileUnit();
-  if (!CU.Verify())
+  if (CU.isNull())
     return;
 
   unsigned Line = Ty->getLineNumber();
@@ -474,7 +474,7 @@ void DwarfDebug::addSourceLine(DIE *Die, const DIType *Ty) {
 /// entry.
 void DwarfDebug::addSourceLine(DIE *Die, const DINameSpace *NS) {
   // If there is no compile unit specified, don't add a line #.
-  if (!NS->getCompileUnit().Verify())
+  if (NS->getCompileUnit().isNull())
     return;
 
   unsigned Line = NS->getLineNumber();
@@ -526,8 +526,12 @@ DIType DwarfDebug::getBlockByrefType(DIType Ty, std::string Name) {
   }
 
   DICompositeType blockStruct = DICompositeType(subType.getNode());
+
   DIArray Elements = blockStruct.getTypeArray();
 
+  if (Elements.isNull())
+    return Ty;
+
   for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
     DIDescriptor Element = Elements.getElement(i);
     DIDerivedType DT = DIDerivedType(Element.getNode());
@@ -673,6 +677,7 @@ void DwarfDebug::addBlockByrefAddress(DbgVariable *&DV, DIE *Die,
   DIDescriptor varField = DIDescriptor();
   DIDescriptor forwardingField = DIDescriptor();
 
+
   for (unsigned i = 0, N = Fields.getNumElements(); i < N; ++i) {
     DIDescriptor Element = Fields.getElement(i);
     DIDerivedType DT = DIDerivedType(Element.getNode());
@@ -683,6 +688,10 @@ void DwarfDebug::addBlockByrefAddress(DbgVariable *&DV, DIE *Die,
       varField = Element;
   }
 
+  assert(!varField.isNull() && "Can't find byref variable in Block struct");
+  assert(!forwardingField.isNull()
+         && "Can't find forwarding field in Block struct");
+
   // Get the offsets for the forwarding field and the variable field.
   unsigned int forwardingFieldOffset =
     DIDerivedType(forwardingField.getNode()).getOffsetInBits() >> 3;
@@ -772,7 +781,9 @@ void DwarfDebug::addAddress(DIE *Die, unsigned Attribute,
 
 /// addToContextOwner - Add Die into the list of its context owner's children.
 void DwarfDebug::addToContextOwner(DIE *Die, DIDescriptor Context) {
-  if (Context.isType()) {
+  if (Context.isNull())
+    ModuleCU->addDie(Die);
+  else if (Context.isType()) {
     DIE *ContextDIE = getOrCreateTypeDIE(DIType(Context.getNode()));
     ContextDIE->addChild(Die);
   } else if (Context.isNameSpace()) {
@@ -809,7 +820,7 @@ DIE *DwarfDebug::getOrCreateTypeDIE(DIType Ty) {
 
 /// addType - Add a new type attribute to the specified entity.
 void DwarfDebug::addType(DIE *Entity, DIType Ty) {
-  if (!Ty.isValid())
+  if (Ty.isNull())
     return;
 
   // Check for pre-existence.
@@ -895,9 +906,9 @@ void DwarfDebug::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
     // Add enumerators to enumeration type.
     for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
       DIE *ElemDie = NULL;
-      DIDescriptor Enum(Elements.getElement(i).getNode());
-      if (Enum.isEnumerator()) {
-        ElemDie = constructEnumTypeDIE(DIEnumerator(Enum.getNode()));
+      DIEnumerator Enum(Elements.getElement(i).getNode());
+      if (!Enum.isNull()) {
+        ElemDie = constructEnumTypeDIE(&Enum);
         Buffer.addChild(ElemDie);
       }
     }
@@ -928,17 +939,18 @@ void DwarfDebug::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
     DIArray Elements = CTy.getTypeArray();
 
     // A forward struct declared type may not have elements available.
-    unsigned N = Elements.getNumElements();
-    if (N == 0)
+    if (Elements.isNull())
       break;
 
     // Add elements to structure type.
-    for (unsigned i = 0; i < N; ++i) {
+    for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
       DIDescriptor Element = Elements.getElement(i);
+      if (Element.isNull())
+        continue;
       DIE *ElemDie = NULL;
-      if (Element.isSubprogram())
+      if (Element.getTag() == dwarf::DW_TAG_subprogram)
         ElemDie = createSubprogramDIE(DISubprogram(Element.getNode()));
-      else if (Element.isVariable()) {
+      else if (Element.getTag() == dwarf::DW_TAG_auto_variable) {
         DIVariable DV(Element.getNode());
         ElemDie = new DIE(dwarf::DW_TAG_variable);
         addString(ElemDie, dwarf::DW_AT_name, dwarf::DW_FORM_string,
@@ -947,10 +959,8 @@ void DwarfDebug::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
         addUInt(ElemDie, dwarf::DW_AT_declaration, dwarf::DW_FORM_flag, 1);
         addUInt(ElemDie, dwarf::DW_AT_external, dwarf::DW_FORM_flag, 1);
         addSourceLine(ElemDie, &DV);
-      } else if (Element.isDerivedType())
+      } else
         ElemDie = createMemberDIE(DIDerivedType(Element.getNode()));
-      else
-        continue;
       Buffer.addChild(ElemDie);
     }
 
@@ -963,7 +973,7 @@ void DwarfDebug::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
               dwarf::DW_FORM_data1, RLang);
 
     DICompositeType ContainingType = CTy.getContainingType();
-    if (DIDescriptor(ContainingType.getNode()).isCompositeType())
+    if (!ContainingType.isNull())
       addDIEEntry(&Buffer, dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4, 
                   getOrCreateTypeDIE(DIType(ContainingType.getNode())));
     break;
@@ -1041,11 +1051,11 @@ void DwarfDebug::constructArrayTypeDIE(DIE &Buffer,
 }
 
 /// constructEnumTypeDIE - Construct enum type DIE from DIEnumerator.
-DIE *DwarfDebug::constructEnumTypeDIE(DIEnumerator ETy) {
+DIE *DwarfDebug::constructEnumTypeDIE(DIEnumerator *ETy) {
   DIE *Enumerator = new DIE(dwarf::DW_TAG_enumerator);
-  StringRef Name = ETy.getName();
+  StringRef Name = ETy->getName();
   addString(Enumerator, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
-  int64_t Value = ETy.getEnumValue();
+  int64_t Value = ETy->getEnumValue();
   addSInt(Enumerator, dwarf::DW_AT_const_value, dwarf::DW_FORM_sdata, Value);
   return Enumerator;
 }
@@ -1189,7 +1199,7 @@ DIE *DwarfDebug::createSubprogramDIE(const DISubprogram &SP, bool MakeDecl) {
   DIArray Args = SPTy.getTypeArray();
   unsigned SPTag = SPTy.getTag();
 
-  if (Args.getNumElements() == 0 || SPTag != dwarf::DW_TAG_subroutine_type)
+  if (Args.isNull() || SPTag != dwarf::DW_TAG_subroutine_type)
     addType(SPDie, SPTy);
   else
     addType(SPDie, DIType(Args.getElement(0).getNode()));
@@ -1272,9 +1282,11 @@ DbgScope *DwarfDebug::getUpdatedDbgScope(MDNode *N, const MachineInstr *MI,
     Parent->addScope(NScope);
   } else if (DIDescriptor(N).isLexicalBlock()) {
     DILexicalBlock DB(N);
-    Parent = getUpdatedDbgScope(DB.getContext().getNode(), MI, InlinedAt);
-    NScope->setParent(Parent);
-    Parent->addScope(NScope);
+    if (!DB.getContext().isNull()) {
+      Parent = getUpdatedDbgScope(DB.getContext().getNode(), MI, InlinedAt);
+      NScope->setParent(Parent);
+      Parent->addScope(NScope);
+    }
   }
 
   NScope->setFirstInsn(MI);
@@ -1306,7 +1318,8 @@ DbgScope *DwarfDebug::getOrCreateAbstractScope(MDNode *N) {
   if (Scope.isLexicalBlock()) {
     DILexicalBlock DB(N);
     DIDescriptor ParentDesc = DB.getContext();
-    Parent = getOrCreateAbstractScope(ParentDesc.getNode());
+    if (!ParentDesc.isNull())
+      Parent = getOrCreateAbstractScope(ParentDesc.getNode());
   }
 
   AScope = new DbgScope(Parent, DIDescriptor(N), NULL);
@@ -1409,9 +1422,10 @@ DIE *DwarfDebug::constructInlinedScopeDIE(DbgScope *Scope) {
   // Ignore empty scopes.
   if (StartID == EndID && StartID != 0)
     return NULL;
-  if (!Scope->getScopeNode())
-    return NULL;
+
   DIScope DS(Scope->getScopeNode());
+  if (DS.isNull())
+    return NULL;
   DIE *ScopeDIE = new DIE(dwarf::DW_TAG_inlined_subroutine);
 
   DISubprogram InlinedSP = getDISubprogram(DS.getNode());
@@ -1533,12 +1547,15 @@ void DwarfDebug::addPubTypes(DISubprogram SP) {
     return;
 
   DIArray Args = SPTy.getTypeArray();
+  if (Args.isNull()) 
+    return;
+
   for (unsigned i = 0, e = Args.getNumElements(); i != e; ++i) {
     DIType ATy(Args.getElement(i).getNode());
-    if (!ATy.isValid())
+    if (ATy.isNull())
       continue;
     DICompositeType CATy = getDICompositeType(ATy);
-    if (DIDescriptor(CATy.getNode()).Verify() && !CATy.getName().empty()) {
+    if (!CATy.isNull() && !CATy.getName().empty()) {
       if (DIEEntry *Entry = ModuleCU->getDIEEntry(CATy.getNode()))
         ModuleCU->addGlobalType(CATy.getName(), Entry->getEntry());
     }
@@ -1547,24 +1564,26 @@ void DwarfDebug::addPubTypes(DISubprogram SP) {
 
 /// constructScopeDIE - Construct a DIE for this scope.
 DIE *DwarfDebug::constructScopeDIE(DbgScope *Scope) {
-  if (!Scope || !Scope->getScopeNode())
-    return NULL;
- 
-  DIScope DS(Scope->getScopeNode());
-  DIE *ScopeDIE = NULL;
-  if (Scope->getInlinedAt())
-    ScopeDIE = constructInlinedScopeDIE(Scope);
-  else if (DS.isSubprogram()) {
-    if (Scope->isAbstractScope())
-      ScopeDIE = ModuleCU->getDIE(DS.getNode());
-    else
-      ScopeDIE = updateSubprogramScopeDIE(DS.getNode());
-  }
-  else {
-    ScopeDIE = constructLexicalScopeDIE(Scope);
-    if (!ScopeDIE) return NULL;
-  }
-  
+ if (!Scope)
+  return NULL;
+ DIScope DS(Scope->getScopeNode());
+ if (DS.isNull())
+   return NULL;
+
+ DIE *ScopeDIE = NULL;
+ if (Scope->getInlinedAt())
+   ScopeDIE = constructInlinedScopeDIE(Scope);
+ else if (DS.isSubprogram()) {
+   if (Scope->isAbstractScope())
+     ScopeDIE = ModuleCU->getDIE(DS.getNode());
+   else
+     ScopeDIE = updateSubprogramScopeDIE(DS.getNode());
+ }
+ else {
+   ScopeDIE = constructLexicalScopeDIE(Scope);
+   if (!ScopeDIE) return NULL;
+ }
+
   // Add variables to scope.
   SmallVector<DbgVariable *, 8> &Variables = Scope->getVariables();
   for (unsigned i = 0, N = Variables.size(); i < N; ++i) {
@@ -2050,6 +2069,7 @@ bool DwarfDebug::extractScopeInformation() {
       if (DL.isUnknown()) continue;
       DILocation DLT = MF->getDILocation(DL);
       DIScope DLTScope = DLT.getScope();
+      if (DLTScope.isNull()) continue;
       // There is no need to create another DIE for compile unit. For all
       // other scopes, create one DbgScope now. This will be translated
       // into a scope DIE at the end.
@@ -2069,6 +2089,7 @@ bool DwarfDebug::extractScopeInformation() {
       if (DL.isUnknown())  continue;
       DILocation DLT = MF->getDILocation(DL);
       DIScope DLTScope = DLT.getScope();
+      if (DLTScope.isNull())  continue;
       // There is no need to create another DIE for compile unit. For all
       // other scopes, create one DbgScope now. This will be translated
       // into a scope DIE at the end.
@@ -2147,7 +2168,7 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
     DILocation DLT = MF->getDILocation(FDL);
     unsigned LabelID = 0;
     DISubprogram SP = getDISubprogram(DLT.getScope().getNode());
-    if (SP.Verify())
+    if (!SP.isNull())
       LabelID = recordSourceLine(SP.getLineNumber(), 0, 
                                  DLT.getScope().getNode());
     else
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 14be2d7e0f8..55baa921006 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -346,7 +346,7 @@ class DwarfDebug : public DwarfPrinter {
                              DICompositeType *CTy);
 
   /// constructEnumTypeDIE - Construct enum type DIE from DIEnumerator.
-  DIE *constructEnumTypeDIE(DIEnumerator ETy);
+  DIE *constructEnumTypeDIE(DIEnumerator *ETy);
 
   /// createGlobalVariableDIE - Create new DIE using GV.
   DIE *createGlobalVariableDIE(const DIGlobalVariable &GV);
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index 4c7cb8f3aae..e23670d1d1d 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -1219,7 +1219,7 @@ void MachineInstr::print(raw_ostream &OS, const TargetMachine *TM) const {
     DIScope Scope = DLT.getScope();
     OS << " dbg:";
     // Omit the directory, since it's usually long and uninteresting.
-    if (Scope.Verify())
+    if (!Scope.isNull())
       OS << Scope.getFilename();
     else
       OS << "<unknown>";
diff --git a/lib/Target/PIC16/PIC16DebugInfo.cpp b/lib/Target/PIC16/PIC16DebugInfo.cpp
index da4e0278769..877e4ffc6d7 100644
--- a/lib/Target/PIC16/PIC16DebugInfo.cpp
+++ b/lib/Target/PIC16/PIC16DebugInfo.cpp
@@ -333,7 +333,7 @@ void PIC16DbgInfo::EmitCompositeTypeDecls(Module &M) {
   for (DebugInfoFinder::iterator I = DbgFinder.type_begin(),
          E = DbgFinder.type_end(); I != E; ++I) {
     DICompositeType CTy(*I);
-    if (!CTy.Verify())
+    if (CTy.isNull())
       continue;
     if (CTy.getTag() == dwarf::DW_TAG_union_type ||
         CTy.getTag() == dwarf::DW_TAG_structure_type ) {
diff --git a/lib/Transforms/Utils/CloneFunction.cpp b/lib/Transforms/Utils/CloneFunction.cpp
index 62fc2ec10b1..c80827d4983 100644
--- a/lib/Transforms/Utils/CloneFunction.cpp
+++ b/lib/Transforms/Utils/CloneFunction.cpp
@@ -336,14 +336,14 @@ ConstantFoldMappedInstruction(const Instruction *I) {
 
 static MDNode *UpdateInlinedAtInfo(MDNode *InsnMD, MDNode *TheCallMD) {
   DILocation ILoc(InsnMD);
-  if (!ILoc.Verify()) return InsnMD;
+  if (ILoc.isNull()) return InsnMD;
 
   DILocation CallLoc(TheCallMD);
-  if (!CallLoc.Verify()) return InsnMD;
+  if (CallLoc.isNull()) return InsnMD;
 
   DILocation OrigLocation = ILoc.getOrigLocation();
   MDNode *NewLoc = TheCallMD;
-  if (OrigLocation.Verify())
+  if (!OrigLocation.isNull())
     NewLoc = UpdateInlinedAtInfo(OrigLocation.getNode(), TheCallMD);
 
   Value *MDVs[] = {