diff --git a/include/llvm/CodeGen/MachineInstrBuilder.h b/include/llvm/CodeGen/MachineInstrBuilder.h
index 925fe4bcf1f..0574ebc40ce 100644
--- a/include/llvm/CodeGen/MachineInstrBuilder.h
+++ b/include/llvm/CodeGen/MachineInstrBuilder.h
@@ -174,7 +174,8 @@ public:
 
   const MachineInstrBuilder &addMetadata(const MDNode *MD) const {
     MI->addOperand(*MF, MachineOperand::CreateMetadata(MD));
-    assert((MI->isDebugValue() ? MI->getDebugVariable().isVariable() : true) &&
+    assert((MI->isDebugValue() ? static_cast<bool>(MI->getDebugVariable())
+                               : true) &&
            "first MDNode argument of a DBG_VALUE not a DIVariable");
     return *this;
   }
@@ -356,8 +357,8 @@ inline MachineInstrBuilder BuildMI(MachineFunction &MF, DebugLoc DL,
                                    unsigned Reg, unsigned Offset,
                                    const MDNode *Variable, const MDNode *Expr) {
   assert(isa<MDLocalVariable>(Variable) && "not a DIVariable");
-  assert(DIExpression(Expr)->isValid() && "not a DIExpression");
-  assert(DIVariable(Variable)->isValidLocationForIntrinsic(DL) &&
+  assert(cast<MDExpression>(Expr)->isValid() && "not a DIExpression");
+  assert(cast<MDLocalVariable>(Variable)->isValidLocationForIntrinsic(DL) &&
          "Expected inlined-at fields to agree");
   if (IsIndirect)
     return BuildMI(MF, DL, MCID)
@@ -385,7 +386,7 @@ inline MachineInstrBuilder BuildMI(MachineBasicBlock &BB,
                                    unsigned Reg, unsigned Offset,
                                    const MDNode *Variable, const MDNode *Expr) {
   assert(isa<MDLocalVariable>(Variable) && "not a DIVariable");
-  assert(DIExpression(Expr)->isValid() && "not a DIExpression");
+  assert(cast<MDExpression>(Expr)->isValid() && "not a DIExpression");
   MachineFunction &MF = *BB.getParent();
   MachineInstr *MI =
       BuildMI(MF, DL, MCID, IsIndirect, Reg, Offset, Variable, Expr);
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 14ee0159550..3aec779d6e5 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -671,8 +671,8 @@ static bool emitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP) {
   OS << "DEBUG_VALUE: ";
 
   DIVariable V = MI->getDebugVariable();
-  if (V.getContext().isSubprogram()) {
-    StringRef Name = DISubprogram(V.getContext()).getDisplayName();
+  if (DISubprogram SP = dyn_cast<MDSubprogram>(V.getContext())) {
+    StringRef Name = SP.getDisplayName();
     if (!Name.empty())
       OS << Name << ":";
   }
diff --git a/lib/CodeGen/AsmPrinter/DebugLocEntry.h b/lib/CodeGen/AsmPrinter/DebugLocEntry.h
index 0b5b8580cd8..f50ebae7ba6 100644
--- a/lib/CodeGen/AsmPrinter/DebugLocEntry.h
+++ b/lib/CodeGen/AsmPrinter/DebugLocEntry.h
@@ -43,7 +43,7 @@ public:
     Value(const MDNode *Var, const MDNode *Expr, MachineLocation Loc)
         : Variable(Var), Expression(Expr), EntryKind(E_Location), Loc(Loc) {
       assert(isa<MDLocalVariable>(Var));
-      assert(DIExpression(Expr)->isValid());
+      assert(cast<MDExpression>(Expr)->isValid());
     }
 
     /// The variable to which this location entry corresponds.
@@ -75,9 +75,11 @@ public:
     const ConstantInt *getConstantInt() const { return Constant.CIP; }
     MachineLocation getLoc() const { return Loc; }
     const MDNode *getVariableNode() const { return Variable; }
-    DIVariable getVariable() const { return DIVariable(Variable); }
+    DIVariable getVariable() const { return cast<MDLocalVariable>(Variable); }
     bool isBitPiece() const { return getExpression().isBitPiece(); }
-    DIExpression getExpression() const { return DIExpression(Expression); }
+    DIExpression getExpression() const {
+      return cast_or_null<MDExpression>(Expression);
+    }
     friend bool operator==(const Value &, const Value &);
     friend bool operator<(const Value &, const Value &);
   };
@@ -101,10 +103,11 @@ public:
   /// Return true if the merge was successful.
   bool MergeValues(const DebugLocEntry &Next) {
     if (Begin == Next.Begin) {
-      DIExpression Expr(Values[0].Expression);
-      DIVariable Var(Values[0].Variable);
-      DIExpression NextExpr(Next.Values[0].Expression);
-      DIVariable NextVar(Next.Values[0].Variable);
+      DIExpression Expr = cast_or_null<MDExpression>(Values[0].Expression);
+      DIVariable Var = cast_or_null<MDLocalVariable>(Values[0].Variable);
+      DIExpression NextExpr =
+          cast_or_null<MDExpression>(Next.Values[0].Expression);
+      DIVariable NextVar = cast_or_null<MDLocalVariable>(Next.Values[0].Variable);
       if (Var == NextVar && Expr.isBitPiece() &&
           NextExpr.isBitPiece()) {
         addValues(Next.Values);
diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 5eb7915f9ed..57fd8ab200a 100644
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -101,7 +101,7 @@ DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(DIGlobalVariable GV) {
   if (DIE *Die = getDIE(GV))
     return Die;
 
-  assert(GV.isGlobalVariable());
+  assert(GV);
 
   DIScope GVContext = GV.getContext();
   DIType GTy = DD->resolve(GV.getType());
@@ -307,7 +307,7 @@ void DwarfCompileUnit::constructScopeDIE(
 
   DIScope DS(Scope->getScopeNode());
 
-  assert((Scope->getInlinedAt() || !DS.isSubprogram()) &&
+  assert((Scope->getInlinedAt() || !isa<MDSubprogram>(DS)) &&
          "Only handle inlined subprograms here, use "
          "constructSubprogramScopeDIE for non-inlined "
          "subprograms");
@@ -318,7 +318,7 @@ void DwarfCompileUnit::constructScopeDIE(
   // avoid creating un-used children then removing them later when we find out
   // the scope DIE is null.
   std::unique_ptr<DIE> ScopeDIE;
-  if (Scope->getParent() && DS.isSubprogram()) {
+  if (Scope->getParent() && isa<MDSubprogram>(DS)) {
     ScopeDIE = constructInlinedScopeDIE(Scope);
     if (!ScopeDIE)
       return;
@@ -340,7 +340,7 @@ void DwarfCompileUnit::constructScopeDIE(
       // There is no need to emit empty lexical block DIE.
       for (const auto &E : DD->findImportedEntitiesForScope(DS))
         Children.push_back(
-            constructImportedEntityDIE(DIImportedEntity(E.second)));
+            constructImportedEntityDIE(cast<MDImportedEntity>(E.second)));
     }
 
     // If there are only other scopes as children, put them directly in the
@@ -562,9 +562,7 @@ void DwarfCompileUnit::constructSubprogramScopeDIE(LexicalScope *Scope) {
   assert(Scope && Scope->getScopeNode());
   assert(!Scope->getInlinedAt());
   assert(!Scope->isAbstractScope());
-  DISubprogram Sub(Scope->getScopeNode());
-
-  assert(Sub.isSubprogram());
+  DISubprogram Sub = cast<MDSubprogram>(Scope->getScopeNode());
 
   DD->getProcessedSPNodes().insert(Sub);
 
@@ -607,7 +605,7 @@ DwarfCompileUnit::constructAbstractSubprogramScopeDIE(LexicalScope *Scope) {
   if (AbsDef)
     return;
 
-  DISubprogram SP(Scope->getScopeNode());
+  DISubprogram SP = cast<MDSubprogram>(Scope->getScopeNode());
 
   DIE *ContextDIE;
 
@@ -641,14 +639,14 @@ DwarfCompileUnit::constructImportedEntityDIE(const DIImportedEntity &Module) {
   insertDIE(Module, IMDie.get());
   DIE *EntityDie;
   DIDescriptor Entity = resolve(Module.getEntity());
-  if (Entity.isNameSpace())
-    EntityDie = getOrCreateNameSpace(DINameSpace(Entity));
-  else if (Entity.isSubprogram())
-    EntityDie = getOrCreateSubprogramDIE(DISubprogram(Entity));
-  else if (Entity.isType())
-    EntityDie = getOrCreateTypeDIE(DIType(Entity));
-  else if (Entity.isGlobalVariable())
-    EntityDie = getOrCreateGlobalVariableDIE(DIGlobalVariable(Entity));
+  if (auto *NS = dyn_cast<MDNamespace>(Entity))
+    EntityDie = getOrCreateNameSpace(NS);
+  else if (auto *SP = dyn_cast<MDSubprogram>(Entity))
+    EntityDie = getOrCreateSubprogramDIE(SP);
+  else if (auto *T = dyn_cast<MDType>(Entity))
+    EntityDie = getOrCreateTypeDIE(T);
+  else if (auto *GV = dyn_cast<MDGlobalVariable>(Entity))
+    EntityDie = getOrCreateGlobalVariableDIE(GV);
   else
     EntityDie = getDIE(Entity);
   assert(EntityDie);
@@ -681,7 +679,7 @@ void DwarfCompileUnit::finishSubprogramDefinition(DISubprogram SP) {
   }
 }
 void DwarfCompileUnit::collectDeadVariables(DISubprogram SP) {
-  assert(SP.isSubprogram() && "CU's subprogram list contains a non-subprogram");
+  assert(SP && "CU's subprogram list contains a non-subprogram");
   assert(SP.isDefinition() &&
          "CU's subprogram list contains a subprogram declaration");
   DIArray Variables = SP.getVariables();
@@ -693,8 +691,7 @@ void DwarfCompileUnit::collectDeadVariables(DISubprogram SP) {
     SPDIE = getDIE(SP);
   assert(SPDIE);
   for (unsigned vi = 0, ve = Variables.getNumElements(); vi != ve; ++vi) {
-    DIVariable DV(Variables.getElement(vi));
-    assert(DV.isVariable());
+    DIVariable DV = cast<MDLocalVariable>(Variables.getElement(vi));
     DbgVariable NewVar(DV, DIExpression(), DD);
     auto VariableDie = constructVariableDIE(NewVar);
     applyVariableAttributes(NewVar, *VariableDie);
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index ca8554185e6..51620bbf27f 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -134,7 +134,7 @@ template <typename T> T DbgVariable::resolve(DIRef<T> Ref) const {
 }
 
 bool DbgVariable::isBlockByrefVariable() const {
-  assert(Var.isVariable() && "Invalid complex DbgVariable!");
+  assert(Var && "Invalid complex DbgVariable!");
   return Var.isBlockByrefVariable(DD->getTypeIdentifierMap());
 }
 
@@ -171,11 +171,11 @@ DIType DbgVariable::getType() const {
     uint16_t tag = Ty.getTag();
 
     if (tag == dwarf::DW_TAG_pointer_type)
-      subType = resolve(DIDerivedType(Ty).getTypeDerivedFrom());
+      subType = resolve(DITypeRef(cast<MDDerivedType>(Ty)->getBaseType()));
 
-    DIArray Elements = DICompositeType(subType).getElements();
+    DIArray Elements(cast<MDCompositeTypeBase>(subType)->getElements());
     for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
-      DIDerivedType DT(Elements.getElement(i));
+      DIDerivedType DT = cast<MDDerivedTypeBase>(Elements.getElement(i));
       if (getName() == DT.getName())
         return (resolve(DT.getTypeDerivedFrom()));
     }
@@ -302,11 +302,10 @@ void DwarfDebug::addSubprogramNames(DISubprogram SP, DIE &Die) {
 bool DwarfDebug::isSubprogramContext(const MDNode *Context) {
   if (!Context)
     return false;
-  DIDescriptor D(Context);
-  if (D.isSubprogram())
+  if (isa<MDSubprogram>(Context))
     return true;
-  if (D.isType())
-    return isSubprogramContext(resolve(DIType(Context).getContext()));
+  if (DIType T = dyn_cast<MDType>(Context))
+    return isSubprogramContext(resolve(T.getContext()));
   return false;
 }
 
@@ -420,7 +419,7 @@ DwarfCompileUnit &DwarfDebug::constructDwarfCompileUnit(DICompileUnit DIUnit) {
 
 void DwarfDebug::constructAndAddImportedEntityDIE(DwarfCompileUnit &TheCU,
                                                   const MDNode *N) {
-  DIImportedEntity Module(N);
+  DIImportedEntity Module = cast<MDImportedEntity>(N);
   if (DIE *D = TheCU.getOrCreateContextDIE(Module.getContext()))
     D->addChild(TheCU.constructImportedEntityDIE(Module));
 }
@@ -444,12 +443,12 @@ void DwarfDebug::beginModule() {
   SingleCU = CU_Nodes->getNumOperands() == 1;
 
   for (MDNode *N : CU_Nodes->operands()) {
-    DICompileUnit CUNode(N);
+    DICompileUnit CUNode = cast<MDCompileUnit>(N);
     DwarfCompileUnit &CU = constructDwarfCompileUnit(CUNode);
     DIArray ImportedEntities = CUNode.getImportedEntities();
     for (unsigned i = 0, e = ImportedEntities.getNumElements(); i != e; ++i)
       ScopesWithImportedEntities.push_back(std::make_pair(
-          DIImportedEntity(ImportedEntities.getElement(i)).getContext(),
+          cast<MDImportedEntity>(ImportedEntities.getElement(i))->getScope(),
           ImportedEntities.getElement(i)));
     // Stable sort to preserve the order of appearance of imported entities.
     // This is to avoid out-of-order processing of interdependent declarations
@@ -458,24 +457,25 @@ void DwarfDebug::beginModule() {
                      ScopesWithImportedEntities.end(), less_first());
     DIArray GVs = CUNode.getGlobalVariables();
     for (unsigned i = 0, e = GVs.getNumElements(); i != e; ++i)
-      CU.getOrCreateGlobalVariableDIE(DIGlobalVariable(GVs.getElement(i)));
+      CU.getOrCreateGlobalVariableDIE(
+          cast<MDGlobalVariable>(GVs.getElement(i)));
     DIArray SPs = CUNode.getSubprograms();
     for (unsigned i = 0, e = SPs.getNumElements(); i != e; ++i)
       SPMap.insert(std::make_pair(SPs.getElement(i), &CU));
     DIArray EnumTypes = CUNode.getEnumTypes();
     for (unsigned i = 0, e = EnumTypes.getNumElements(); i != e; ++i) {
-      DIType Ty(EnumTypes.getElement(i));
+      DIType Ty = cast<MDType>(EnumTypes.getElement(i));
       // The enum types array by design contains pointers to
       // MDNodes rather than DIRefs. Unique them here.
-      DIType UniqueTy(resolve(Ty.getRef()));
+      DIType UniqueTy = cast<MDType>(resolve(Ty.getRef()));
       CU.getOrCreateTypeDIE(UniqueTy);
     }
     DIArray RetainedTypes = CUNode.getRetainedTypes();
     for (unsigned i = 0, e = RetainedTypes.getNumElements(); i != e; ++i) {
-      DIType Ty(RetainedTypes.getElement(i));
+      DIType Ty = cast<MDType>(RetainedTypes.getElement(i));
       // The retained types array by design contains pointers to
       // MDNodes rather than DIRefs. Unique them here.
-      DIType UniqueTy(resolve(Ty.getRef()));
+      DIType UniqueTy = cast<MDType>(resolve(Ty.getRef()));
       CU.getOrCreateTypeDIE(UniqueTy);
     }
     // Emit imported_modules last so that the relevant context is already
@@ -509,7 +509,7 @@ void DwarfDebug::finishVariableDefinitions() {
 void DwarfDebug::finishSubprogramDefinitions() {
   for (const auto &P : SPMap)
     forBothCUs(*P.second, [&](DwarfCompileUnit &CU) {
-      CU.finishSubprogramDefinition(DISubprogram(P.first));
+      CU.finishSubprogramDefinition(cast<MDSubprogram>(P.first));
     });
 }
 
@@ -520,14 +520,14 @@ void DwarfDebug::collectDeadVariables() {
 
   if (NamedMDNode *CU_Nodes = M->getNamedMetadata("llvm.dbg.cu")) {
     for (MDNode *N : CU_Nodes->operands()) {
-      DICompileUnit TheCU(N);
+      DICompileUnit TheCU = cast<MDCompileUnit>(N);
       // Construct subprogram DIE and add variables DIEs.
       DwarfCompileUnit *SPCU =
           static_cast<DwarfCompileUnit *>(CUMap.lookup(TheCU));
       assert(SPCU && "Unable to find Compile Unit!");
       DIArray Subprograms = TheCU.getSubprograms();
       for (unsigned i = 0, e = Subprograms.getNumElements(); i != e; ++i) {
-        DISubprogram SP(Subprograms.getElement(i));
+        DISubprogram SP = cast<MDSubprogram>(Subprograms.getElement(i));
         if (ProcessedSPNodes.count(SP) != 0)
           continue;
         SPCU->collectDeadVariables(SP);
@@ -732,10 +732,10 @@ void DwarfDebug::collectVariableInfoFromMMITable(
     if (!Scope)
       continue;
 
-    DIVariable DV(VI.Var);
+    DIVariable DV = cast<MDLocalVariable>(VI.Var);
     assert(DV->isValidLocationForIntrinsic(VI.Loc) &&
            "Expected inlined-at fields to agree");
-    DIExpression Expr(VI.Expr);
+    DIExpression Expr = cast_or_null<MDExpression>(VI.Expr);
     ensureAbstractVariableIsCreatedIfScoped(DV, Scope->getScopeNode());
     auto RegVar = make_unique<DbgVariable>(DV, Expr, this, VI.Slot);
     if (InfoHolder.addScopeVariable(Scope, RegVar.get()))
@@ -894,7 +894,7 @@ DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU, DISubprogram SP,
   collectVariableInfoFromMMITable(Processed);
 
   for (const auto &I : DbgValues) {
-    DIVariable DV(I.first);
+    DIVariable DV = cast<MDLocalVariable>(I.first);
     if (Processed.count(DV))
       continue;
 
@@ -942,8 +942,7 @@ DwarfDebug::collectVariableInfo(DwarfCompileUnit &TheCU, DISubprogram SP,
   // Collect info for variables that were optimized out.
   DIArray Variables = SP.getVariables();
   for (unsigned i = 0, e = Variables.getNumElements(); i != e; ++i) {
-    DIVariable DV(Variables.getElement(i));
-    assert(DV.isVariable());
+    DIVariable DV = cast<MDLocalVariable>(Variables.getElement(i));
     if (!Processed.insert(DV).second)
       continue;
     if (LexicalScope *Scope = LScopes.findLexicalScope(DV.get()->getScope())) {
@@ -1140,8 +1139,8 @@ void DwarfDebug::beginFunction(const MachineFunction *MF) {
 
     // The first mention of a function argument gets the CurrentFnBegin
     // label, so arguments are visible when breaking at function entry.
-    DIVariable DIVar(Ranges.front().first->getDebugVariable());
-    if (DIVar.isVariable() && DIVar.getTag() == dwarf::DW_TAG_arg_variable &&
+    DIVariable DIVar = Ranges.front().first->getDebugVariable();
+    if (DIVar.getTag() == dwarf::DW_TAG_arg_variable &&
         getDISubprogram(DIVar.getContext()).describes(MF->getFunction())) {
       LabelsBeforeInsn[Ranges.front().first] = Asm->getFunctionBegin();
       if (Ranges.front().first->getDebugExpression().isBitPiece()) {
@@ -1198,7 +1197,7 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
   Asm->OutStreamer.getContext().setDwarfCompileUnitID(0);
 
   LexicalScope *FnScope = LScopes.getCurrentFunctionScope();
-  DISubprogram SP(FnScope->getScopeNode());
+  DISubprogram SP = cast<MDSubprogram>(FnScope->getScopeNode());
   DwarfCompileUnit &TheCU = *SPMap.lookup(SP);
 
   SmallPtrSet<const MDNode *, 16> ProcessedVars;
@@ -1228,13 +1227,11 @@ void DwarfDebug::endFunction(const MachineFunction *MF) {
 #endif
   // Construct abstract scopes.
   for (LexicalScope *AScope : LScopes.getAbstractScopesList()) {
-    DISubprogram SP(AScope->getScopeNode());
-    assert(SP.isSubprogram());
+    DISubprogram SP = cast<MDSubprogram>(AScope->getScopeNode());
     // Collect info for variables that were optimized out.
     DIArray Variables = SP.getVariables();
     for (unsigned i = 0, e = Variables.getNumElements(); i != e; ++i) {
-      DIVariable DV(Variables.getElement(i));
-      assert(DV && DV.isVariable());
+      DIVariable DV = cast<MDLocalVariable>(Variables.getElement(i));
       if (!ProcessedVars.insert(DV).second)
         continue;
       ensureAbstractVariableIsCreated(DV, DV.getContext());
@@ -1269,12 +1266,11 @@ void DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, const MDNode *S,
   StringRef Dir;
   unsigned Src = 1;
   unsigned Discriminator = 0;
-  if (DIScope Scope = DIScope(S)) {
-    assert(Scope.isScope());
+  if (DIScope Scope = cast_or_null<MDScope>(S)) {
     Fn = Scope.getFilename();
     Dir = Scope.getDirectory();
-    if (Scope.isLexicalBlockFile())
-      Discriminator = DILexicalBlockFile(S).getDiscriminator();
+    if (DILexicalBlockFile LBF = dyn_cast<MDLexicalBlockFile>(Scope))
+      Discriminator = LBF.getDiscriminator();
 
     unsigned CUID = Asm->OutStreamer.getContext().getDwarfCompileUnitID();
     Src = static_cast<DwarfCompileUnit &>(*InfoHolder.getUnits()[CUID])
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 993d421b7aa..92c37c52f18 100644
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -153,7 +153,7 @@ public:
   }
 
   bool variableHasComplexAddress() const {
-    assert(Var.isVariable() && "Invalid complex DbgVariable!");
+    assert(Var && "Invalid complex DbgVariable!");
     assert(Expr.size() == 1 &&
            "variableHasComplexAddress() invoked on multi-FI variable");
     return Expr.back().getNumElements() > 0;
diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index dc234dde7f4..6daecc7d3e7 100644
--- a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -175,8 +175,8 @@ static bool isShareableAcrossCUs(DIDescriptor D) {
   // level already) but may be implementable for some value in projects
   // building multiple independent libraries with LTO and then linking those
   // together.
-  return (D.isType() ||
-          (D.isSubprogram() && !DISubprogram(D).isDefinition())) &&
+  return (isa<MDType>(D) ||
+          (isa<MDSubprogram>(D) && !cast<MDSubprogram>(D)->isDefinition())) &&
          !GenerateDwarfTypeUnits;
 }
 
@@ -397,7 +397,7 @@ void DwarfUnit::addSourceLine(DIE &Die, unsigned Line, StringRef File,
 /// addSourceLine - Add location information to specified debug information
 /// entry.
 void DwarfUnit::addSourceLine(DIE &Die, DIVariable V) {
-  assert(V.isVariable());
+  assert(V);
 
   addSourceLine(Die, V.getLineNumber(), V.getContext().getFilename(),
                 V.getContext().getDirectory());
@@ -406,7 +406,7 @@ void DwarfUnit::addSourceLine(DIE &Die, DIVariable V) {
 /// addSourceLine - Add location information to specified debug information
 /// entry.
 void DwarfUnit::addSourceLine(DIE &Die, DIGlobalVariable G) {
-  assert(G.isGlobalVariable());
+  assert(G);
 
   addSourceLine(Die, G.getLineNumber(), G.getFilename(), G.getDirectory());
 }
@@ -414,7 +414,7 @@ void DwarfUnit::addSourceLine(DIE &Die, DIGlobalVariable G) {
 /// addSourceLine - Add location information to specified debug information
 /// entry.
 void DwarfUnit::addSourceLine(DIE &Die, DISubprogram SP) {
-  assert(SP.isSubprogram());
+  assert(SP);
 
   addSourceLine(Die, SP.getLineNumber(), SP.getFilename(), SP.getDirectory());
 }
@@ -422,7 +422,7 @@ void DwarfUnit::addSourceLine(DIE &Die, DISubprogram SP) {
 /// addSourceLine - Add location information to specified debug information
 /// entry.
 void DwarfUnit::addSourceLine(DIE &Die, DIType Ty) {
-  assert(Ty.isType());
+  assert(Ty);
 
   addSourceLine(Die, Ty.getLineNumber(), Ty.getFilename(), Ty.getDirectory());
 }
@@ -430,7 +430,7 @@ void DwarfUnit::addSourceLine(DIE &Die, DIType Ty) {
 /// addSourceLine - Add location information to specified debug information
 /// entry.
 void DwarfUnit::addSourceLine(DIE &Die, DIObjCProperty Ty) {
-  assert(Ty.isObjCProperty());
+  assert(Ty);
 
   DIFile File = Ty.getFile();
   addSourceLine(Die, Ty.getLineNumber(), File.getFilename(),
@@ -529,12 +529,12 @@ void DwarfUnit::addBlockByrefAddress(const DbgVariable &DV, DIE &Die,
   StringRef varName = DV.getName();
 
   if (Tag == dwarf::DW_TAG_pointer_type) {
-    DIDerivedType DTy(Ty);
+    DIDerivedType DTy = cast<MDDerivedType>(Ty);
     TmpTy = resolve(DTy.getTypeDerivedFrom());
     isPointer = true;
   }
 
-  DICompositeType blockStruct(TmpTy);
+  DICompositeType blockStruct = cast<MDCompositeTypeBase>(TmpTy);
 
   // Find the __forwarding field and the variable field in the __Block_byref
   // struct.
@@ -543,7 +543,7 @@ void DwarfUnit::addBlockByrefAddress(const DbgVariable &DV, DIE &Die,
   DIDerivedType forwardingField;
 
   for (unsigned i = 0, N = Fields.getNumElements(); i < N; ++i) {
-    DIDerivedType DT(Fields.getElement(i));
+    DIDerivedType DT = cast<MDDerivedTypeBase>(Fields.getElement(i));
     StringRef fieldName = DT.getName();
     if (fieldName == "__forwarding")
       forwardingField = DT;
@@ -599,8 +599,7 @@ void DwarfUnit::addBlockByrefAddress(const DbgVariable &DV, DIE &Die,
 
 /// Return true if type encoding is unsigned.
 static bool isUnsignedDIType(DwarfDebug *DD, DIType Ty) {
-  DIDerivedType DTy(Ty);
-  if (DTy.isDerivedType()) {
+  if (DIDerivedType DTy = dyn_cast<MDDerivedTypeBase>(Ty)) {
     dwarf::Tag T = (dwarf::Tag)Ty.getTag();
     // Encode pointer constants as unsigned bytes. This is used at least for
     // null pointer constant emission.
@@ -630,8 +629,7 @@ static bool isUnsignedDIType(DwarfDebug *DD, DIType Ty) {
     return false;
   }
 
-  DIBasicType BTy(Ty);
-  assert(BTy.isBasicType());
+  DIBasicType BTy = cast<MDBasicType>(Ty);
   unsigned Encoding = BTy.getEncoding();
   assert((Encoding == dwarf::DW_ATE_unsigned ||
           Encoding == dwarf::DW_ATE_unsigned_char ||
@@ -668,8 +666,8 @@ static uint64_t getBaseTypeSize(DwarfDebug *DD, DIDerivedType Ty) {
       BaseType.getTag() == dwarf::DW_TAG_rvalue_reference_type)
     return Ty.getSizeInBits();
 
-  if (BaseType.isDerivedType())
-    return getBaseTypeSize(DD, DIDerivedType(BaseType));
+  if (auto *DT = dyn_cast<MDDerivedTypeBase>(BaseType))
+    return getBaseTypeSize(DD, DT);
 
   return BaseType.getSizeInBits();
 }
@@ -771,25 +769,23 @@ void DwarfUnit::addTemplateParams(DIE &Buffer, DIArray TParams) {
   // Add template parameters.
   for (unsigned i = 0, e = TParams.getNumElements(); i != e; ++i) {
     DIDescriptor Element = TParams.getElement(i);
-    if (Element.isTemplateTypeParameter())
-      constructTemplateTypeParameterDIE(Buffer,
-                                        DITemplateTypeParameter(Element));
-    else if (Element.isTemplateValueParameter())
-      constructTemplateValueParameterDIE(Buffer,
-                                         DITemplateValueParameter(Element));
+    if (auto *TTP = dyn_cast<MDTemplateTypeParameter>(Element))
+      constructTemplateTypeParameterDIE(Buffer, TTP);
+    else if (auto *TVP = dyn_cast<MDTemplateValueParameter>(Element))
+      constructTemplateValueParameterDIE(Buffer, TVP);
   }
 }
 
 /// getOrCreateContextDIE - Get context owner's DIE.
 DIE *DwarfUnit::getOrCreateContextDIE(DIScope Context) {
-  if (!Context || Context.isFile())
+  if (!Context || isa<MDFile>(Context))
     return &getUnitDie();
-  if (Context.isType())
-    return getOrCreateTypeDIE(DIType(Context));
-  if (Context.isNameSpace())
-    return getOrCreateNameSpace(DINameSpace(Context));
-  if (Context.isSubprogram())
-    return getOrCreateSubprogramDIE(DISubprogram(Context));
+  if (auto *T = dyn_cast<MDType>(Context))
+    return getOrCreateTypeDIE(T);
+  if (auto *NS = dyn_cast<MDNamespace>(Context))
+    return getOrCreateNameSpace(NS);
+  if (auto *SP = dyn_cast<MDSubprogram>(Context))
+    return getOrCreateSubprogramDIE(SP);
   return getDIE(Context);
 }
 
@@ -815,14 +811,14 @@ DIE *DwarfUnit::getOrCreateTypeDIE(const MDNode *TyNode) {
   if (!TyNode)
     return nullptr;
 
-  DIType Ty(TyNode);
-  assert(Ty.isType());
+  DIType Ty = cast<MDType>(TyNode);
   assert(Ty == resolve(Ty.getRef()) &&
          "type was not uniqued, possible ODR violation.");
 
   // DW_TAG_restrict_type is not supported in DWARF2
   if (Ty.getTag() == dwarf::DW_TAG_restrict_type && DD->getDwarfVersion() <= 2)
-    return getOrCreateTypeDIE(resolve(DIDerivedType(Ty).getTypeDerivedFrom()));
+    return getOrCreateTypeDIE(
+        resolve(DITypeRef(cast<MDDerivedType>(Ty)->getBaseType())));
 
   // Construct the context before querying for the existence of the DIE in case
   // such construction creates the DIE.
@@ -838,10 +834,9 @@ DIE *DwarfUnit::getOrCreateTypeDIE(const MDNode *TyNode) {
 
   updateAcceleratorTables(Context, Ty, TyDIE);
 
-  if (Ty.isBasicType())
-    constructTypeDIE(TyDIE, DIBasicType(Ty));
-  else if (Ty.isCompositeType()) {
-    DICompositeType CTy(Ty);
+  if (auto *BT = dyn_cast<MDBasicType>(Ty))
+    constructTypeDIE(TyDIE, BT);
+  else if (DICompositeType CTy = dyn_cast<MDCompositeTypeBase>(Ty)) {
     if (GenerateDwarfTypeUnits && !Ty.isForwardDecl())
       if (MDString *TypeId = CTy.getIdentifier()) {
         DD->addDwarfTypeUnitType(getCU(), TypeId->getString(), TyDIE, CTy);
@@ -850,8 +845,7 @@ DIE *DwarfUnit::getOrCreateTypeDIE(const MDNode *TyNode) {
       }
     constructTypeDIE(TyDIE, CTy);
   } else {
-    assert(Ty.isDerivedType() && "Unknown kind of DIType");
-    constructTypeDIE(TyDIE, DIDerivedType(Ty));
+    constructTypeDIE(TyDIE, cast<MDDerivedType>(Ty));
   }
 
   return &TyDIE;
@@ -861,8 +855,7 @@ void DwarfUnit::updateAcceleratorTables(DIScope Context, DIType Ty,
                                         const DIE &TyDIE) {
   if (!Ty.getName().empty() && !Ty.isForwardDecl()) {
     bool IsImplementation = 0;
-    if (Ty.isCompositeType()) {
-      DICompositeType CT(Ty);
+    if (DICompositeType CT = dyn_cast<MDCompositeTypeBase>(Ty)) {
       // A runtime language of 0 actually means C/C++ and that any
       // non-negative value is some version of Objective-C/C++.
       IsImplementation = (CT.getRunTimeLang() == 0) || CT.isObjcClassComplete();
@@ -870,8 +863,8 @@ void DwarfUnit::updateAcceleratorTables(DIScope Context, DIType Ty,
     unsigned Flags = IsImplementation ? dwarf::DW_FLAG_type_implementation : 0;
     DD->addAccelType(Ty.getName(), TyDIE, Flags);
 
-    if (!Context || Context.isCompileUnit() || Context.isFile() ||
-        Context.isNameSpace())
+    if (!Context || isa<MDCompileUnit>(Context) || isa<MDFile>(Context) ||
+        isa<MDNamespace>(Context))
       addGlobalType(Ty, TyDIE, Context);
   }
 }
@@ -912,7 +905,7 @@ std::string DwarfUnit::getParentContextString(DIScope Context) const {
 
   std::string CS;
   SmallVector<DIScope, 1> Parents;
-  while (!Context.isCompileUnit()) {
+  while (!isa<MDCompileUnit>(Context)) {
     Parents.push_back(Context);
     if (Context.getContext())
       Context = resolve(Context.getContext());
@@ -929,7 +922,7 @@ std::string DwarfUnit::getParentContextString(DIScope Context) const {
        I != E; ++I) {
     DIScope Ctx = *I;
     StringRef Name = Ctx.getName();
-    if (Name.empty() && Ctx.isNameSpace())
+    if (Name.empty() && isa<MDNamespace>(Ctx))
       Name = "(anonymous namespace)";
     if (!Name.empty()) {
       CS += Name;
@@ -1020,7 +1013,7 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
     break;
   case dwarf::DW_TAG_subroutine_type: {
     // Add return type. A void return won't have a type.
-    DITypeArray Elements = DISubroutineType(CTy).getTypeArray();
+    DITypeArray Elements(cast<MDSubroutineType>(CTy)->getTypeArray());
     DIType RTy(resolve(Elements.getElement(0)));
     if (RTy)
       addType(Buffer, RTy);
@@ -1053,10 +1046,11 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
     DIArray Elements = CTy.getElements();
     for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
       DIDescriptor Element = Elements.getElement(i);
-      if (Element.isSubprogram())
-        getOrCreateSubprogramDIE(DISubprogram(Element));
-      else if (Element.isDerivedType()) {
-        DIDerivedType DDTy(Element);
+      if (!Element)
+        continue;
+      if (auto *SP = dyn_cast<MDSubprogram>(Element))
+        getOrCreateSubprogramDIE(SP);
+      else if (DIDerivedType DDTy = dyn_cast<MDDerivedTypeBase>(Element)) {
         if (DDTy.getTag() == dwarf::DW_TAG_friend) {
           DIE &ElemDie = createAndAddDIE(dwarf::DW_TAG_friend, Buffer);
           addType(ElemDie, resolve(DDTy.getTypeDerivedFrom()),
@@ -1066,8 +1060,7 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
         } else {
           constructMemberDIE(Buffer, DDTy);
         }
-      } else if (Element.isObjCProperty()) {
-        DIObjCProperty Property(Element);
+      } else if (DIObjCProperty Property = dyn_cast<MDObjCProperty>(Element)) {
         DIE &ElemDie = createAndAddDIE(Property.getTag(), Buffer);
         StringRef PropertyName = Property.getObjCPropertyName();
         addString(ElemDie, dwarf::DW_AT_APPLE_property_name, PropertyName);
@@ -1102,8 +1095,7 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
           Entry = createDIEEntry(ElemDie);
           insertDIEEntry(Element, Entry);
         }
-      } else
-        continue;
+      }
     }
 
     if (CTy.isAppleBlockExtension())
@@ -1111,8 +1103,8 @@ void DwarfUnit::constructTypeDIE(DIE &Buffer, DICompositeType CTy) {
 
     // This is outside the DWARF spec, but GDB expects a DW_AT_containing_type
     // inside C++ composite types to point to the base class with the vtable.
-    DICompositeType ContainingType(resolve(CTy.getContainingType()));
-    if (ContainingType)
+    if (DICompositeType ContainingType =
+            dyn_cast_or_null<MDCompositeType>(resolve(CTy.getContainingType())))
       addDIEEntry(Buffer, dwarf::DW_AT_containing_type,
                   *getOrCreateTypeDIE(ContainingType));
 
@@ -1434,7 +1426,7 @@ void DwarfUnit::constructArrayTypeDIE(DIE &Buffer, DICompositeType CTy) {
   for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
     DIDescriptor Element = Elements.getElement(i);
     if (Element.getTag() == dwarf::DW_TAG_subrange_type)
-      constructSubrangeDIE(Buffer, DISubrange(Element), IdxTy);
+      constructSubrangeDIE(Buffer, cast<MDSubrange>(Element), IdxTy);
   }
 }
 
@@ -1444,8 +1436,8 @@ void DwarfUnit::constructEnumTypeDIE(DIE &Buffer, DICompositeType CTy) {
 
   // Add enumerators to enumeration type.
   for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
-    DIEnumerator Enum(Elements.getElement(i));
-    if (Enum.isEnumerator()) {
+    DIEnumerator Enum = dyn_cast_or_null<MDEnumerator>(Elements.getElement(i));
+    if (Enum) {
       DIE &Enumerator = createAndAddDIE(dwarf::DW_TAG_enumerator, Buffer);
       StringRef Name = Enum.getName();
       addString(Enumerator, dwarf::DW_AT_name, Name);
diff --git a/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp b/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
index 39a76d629ad..2bd311bc7d8 100644
--- a/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
+++ b/lib/CodeGen/AsmPrinter/WinCodeViewLineTables.cpp
@@ -20,12 +20,11 @@ namespace llvm {
 
 StringRef WinCodeViewLineTables::getFullFilepath(const MDNode *S) {
   assert(S);
-  DIDescriptor D(S);
-  assert((D.isCompileUnit() || D.isFile() || D.isSubprogram() ||
-          D.isLexicalBlockFile() || D.isLexicalBlock()) &&
+  assert((isa<MDCompileUnit>(S) || isa<MDFile>(S) || isa<MDSubprogram>(S) ||
+          isa<MDLexicalBlockBase>(S)) &&
          "Unexpected scope info");
 
-  DIScope Scope(S);
+  DIScope Scope = cast<MDScope>(S);
   StringRef Dir = Scope.getDirectory(),
             Filename = Scope.getFilename();
   char *&Result = DirAndFilenameToFilepathMap[std::make_pair(Dir, Filename)];
diff --git a/lib/CodeGen/InlineSpiller.cpp b/lib/CodeGen/InlineSpiller.cpp
index f5db72d184d..db7466db651 100644
--- a/lib/CodeGen/InlineSpiller.cpp
+++ b/lib/CodeGen/InlineSpiller.cpp
@@ -1232,7 +1232,7 @@ void InlineSpiller::spillAroundUses(unsigned Reg) {
       DebugLoc DL = MI->getDebugLoc();
       DEBUG(dbgs() << "Modifying debug info due to spill:" << "\t" << *MI);
       MachineBasicBlock *MBB = MI->getParent();
-      assert(DIVariable(Var)->isValidLocationForIntrinsic(DL) &&
+      assert(cast<MDLocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
              "Expected inlined-at fields to agree");
       BuildMI(*MBB, MBB->erase(MI), DL, TII.get(TargetOpcode::DBG_VALUE))
           .addFrameIndex(StackSlot)
diff --git a/lib/CodeGen/LexicalScopes.cpp b/lib/CodeGen/LexicalScopes.cpp
index 3e978361481..938fa0a8de3 100644
--- a/lib/CodeGen/LexicalScopes.cpp
+++ b/lib/CodeGen/LexicalScopes.cpp
@@ -157,8 +157,8 @@ LexicalScopes::getOrCreateRegularScope(const MDLocalScope *Scope) {
                                                     false)).first;
 
   if (!Parent) {
-    assert(DIDescriptor(Scope).isSubprogram());
-    assert(DISubprogram(Scope).describes(MF->getFunction()));
+    assert(
+        DISubprogram(cast<MDSubprogram>(Scope)).describes(MF->getFunction()));
     assert(!CurrentFnLexicalScope);
     CurrentFnLexicalScope = &I->second;
   }
diff --git a/lib/CodeGen/LiveDebugVariables.cpp b/lib/CodeGen/LiveDebugVariables.cpp
index 69869fd616a..cf02e31240f 100644
--- a/lib/CodeGen/LiveDebugVariables.cpp
+++ b/lib/CodeGen/LiveDebugVariables.cpp
@@ -358,7 +358,7 @@ public:
 } // namespace
 
 void UserValue::print(raw_ostream &OS, const TargetRegisterInfo *TRI) {
-  DIVariable DV(Variable);
+  DIVariable DV = cast<MDLocalVariable>(Variable);
   OS << "!\"";
   DV.printExtendedName(OS);
   OS << "\"\t";
@@ -944,7 +944,8 @@ void UserValue::insertDebugValue(MachineBasicBlock *MBB, SlotIndex Idx,
   MachineOperand &Loc = locations[LocNo];
   ++NumInsertedDebugValues;
 
-  assert(DIVariable(Variable)->isValidLocationForIntrinsic(getDebugLoc()) &&
+  assert(cast<MDLocalVariable>(Variable)
+             ->isValidLocationForIntrinsic(getDebugLoc()) &&
          "Expected inlined-at fields to agree");
   if (Loc.isReg())
     BuildMI(*MBB, I, getDebugLoc(), TII.get(TargetOpcode::DBG_VALUE),
diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index f1c0d8ef2ad..2fdc2bcaa42 100644
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -1619,11 +1619,8 @@ void MachineInstr::print(raw_ostream &OS, bool SkipOpers) const {
     }
     if (isDebugValue() && MO.isMetadata()) {
       // Pretty print DBG_VALUE instructions.
-      const MDNode *MD = MO.getMetadata();
-      DIDescriptor DI(MD);
-      DIVariable DIV(MD);
-
-      if (DI.isVariable() && !DIV.getName().empty())
+      DIVariable DIV = dyn_cast<MDLocalVariable>(MO.getMetadata());
+      if (DIV && !DIV.getName().empty())
         OS << "!\"" << DIV.getName() << '\"';
       else
         MO.print(OS, TRI);
@@ -1713,7 +1710,7 @@ void MachineInstr::print(raw_ostream &OS, bool SkipOpers) const {
   // Print debug location information.
   if (isDebugValue() && getOperand(e - 2).isMetadata()) {
     if (!HaveSemi) OS << ";";
-    DIVariable DV(getOperand(e - 2).getMetadata());
+    DIVariable DV = cast<MDLocalVariable>(getOperand(e - 2).getMetadata());
     OS << " line no:" <<  DV.getLineNumber();
     if (auto *InlinedAt = DV.getInlinedAt()) {
       DebugLoc InlinedAtDL(InlinedAt);
diff --git a/lib/CodeGen/RegAllocFast.cpp b/lib/CodeGen/RegAllocFast.cpp
index dbf1a903c9f..c311c7ba2b4 100644
--- a/lib/CodeGen/RegAllocFast.cpp
+++ b/lib/CodeGen/RegAllocFast.cpp
@@ -302,7 +302,7 @@ void RAFast::spillVirtReg(MachineBasicBlock::iterator MI,
       bool IsIndirect = DBG->isIndirectDebugValue();
       uint64_t Offset = IsIndirect ? DBG->getOperand(1).getImm() : 0;
       DebugLoc DL = DBG->getDebugLoc();
-      assert(DIVariable(Var)->isValidLocationForIntrinsic(DL) &&
+      assert(cast<MDLocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
              "Expected inlined-at fields to agree");
       MachineInstr *NewDV =
           BuildMI(*MBB, MI, DL, TII->get(TargetOpcode::DBG_VALUE))
@@ -873,8 +873,9 @@ void RAFast::AllocateBasicBlock() {
               const MDNode *Expr = MI->getDebugExpression();
               DebugLoc DL = MI->getDebugLoc();
               MachineBasicBlock *MBB = MI->getParent();
-              assert(DIVariable(Var)->isValidLocationForIntrinsic(DL) &&
-                     "Expected inlined-at fields to agree");
+              assert(
+                  cast<MDLocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
+                  "Expected inlined-at fields to agree");
               MachineInstr *NewDV = BuildMI(*MBB, MBB->erase(MI), DL,
                                             TII->get(TargetOpcode::DBG_VALUE))
                                         .addFrameIndex(SS)
diff --git a/lib/CodeGen/SelectionDAG/FastISel.cpp b/lib/CodeGen/SelectionDAG/FastISel.cpp
index cf26425074a..5ffb826956e 100644
--- a/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -1088,9 +1088,7 @@ bool FastISel::selectIntrinsicCall(const IntrinsicInst *II) {
   }
   case Intrinsic::dbg_declare: {
     const DbgDeclareInst *DI = cast<DbgDeclareInst>(II);
-    DIVariable DIVar(DI->getVariable());
-    assert((!DIVar || DIVar.isVariable()) &&
-           "Variable in DbgDeclareInst should be either null or a DIVariable.");
+    DIVariable DIVar = DI->getVariable();
     if (!DIVar || !FuncInfo.MF->getMMI().hasDebugInfo()) {
       DEBUG(dbgs() << "Dropping debug info for " << *DI << "\n");
       return true;
diff --git a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
index 4547906c275..8eac8eb4f1b 100644
--- a/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
+++ b/lib/CodeGen/SelectionDAG/FunctionLoweringInfo.cpp
@@ -202,9 +202,7 @@ void FunctionLoweringInfo::set(const Function &fn, MachineFunction &mf,
       // during the initial isel pass through the IR so that it is done
       // in a predictable order.
       if (const DbgDeclareInst *DI = dyn_cast<DbgDeclareInst>(I)) {
-        DIVariable DIVar(DI->getVariable());
-        assert((!DIVar || DIVar.isVariable()) &&
-          "Variable in DbgDeclareInst should be either null or a DIVariable.");
+        DIVariable DIVar = DI->getVariable();
         if (MMI.hasDebugInfo() && DIVar && DI->getDebugLoc()) {
           // Don't handle byval struct arguments or VLAs, for example.
           // Non-byval arguments are handled here (they refer to the stack
diff --git a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
index 9de6b753035..64d606a2e2c 100644
--- a/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
+++ b/lib/CodeGen/SelectionDAG/InstrEmitter.cpp
@@ -650,7 +650,7 @@ InstrEmitter::EmitDbgValue(SDDbgValue *SD,
   MDNode *Var = SD->getVariable();
   MDNode *Expr = SD->getExpression();
   DebugLoc DL = SD->getDebugLoc();
-  assert(DIVariable(Var)->isValidLocationForIntrinsic(DL) &&
+  assert(cast<MDLocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
          "Expected inlined-at fields to agree");
 
   if (SD->getKind() == SDDbgValue::FRAMEIX) {
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index fdfdd15ad67..9080e34289e 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -5902,7 +5902,7 @@ SDNode *SelectionDAG::getNodeIfExists(unsigned Opcode, SDVTList VTList,
 SDDbgValue *SelectionDAG::getDbgValue(MDNode *Var, MDNode *Expr, SDNode *N,
                                       unsigned R, bool IsIndirect, uint64_t Off,
                                       DebugLoc DL, unsigned O) {
-  assert(DIVariable(Var)->isValidLocationForIntrinsic(DL) &&
+  assert(cast<MDLocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
          "Expected inlined-at fields to agree");
   return new (Allocator) SDDbgValue(Var, Expr, N, R, IsIndirect, Off, DL, O);
 }
@@ -5911,7 +5911,7 @@ SDDbgValue *SelectionDAG::getDbgValue(MDNode *Var, MDNode *Expr, SDNode *N,
 SDDbgValue *SelectionDAG::getConstantDbgValue(MDNode *Var, MDNode *Expr,
                                               const Value *C, uint64_t Off,
                                               DebugLoc DL, unsigned O) {
-  assert(DIVariable(Var)->isValidLocationForIntrinsic(DL) &&
+  assert(cast<MDLocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
          "Expected inlined-at fields to agree");
   return new (Allocator) SDDbgValue(Var, Expr, C, Off, DL, O);
 }
@@ -5920,7 +5920,7 @@ SDDbgValue *SelectionDAG::getConstantDbgValue(MDNode *Var, MDNode *Expr,
 SDDbgValue *SelectionDAG::getFrameIndexDbgValue(MDNode *Var, MDNode *Expr,
                                                 unsigned FI, uint64_t Off,
                                                 DebugLoc DL, unsigned O) {
-  assert(DIVariable(Var)->isValidLocationForIntrinsic(DL) &&
+  assert(cast<MDLocalVariable>(Var)->isValidLocationForIntrinsic(DL) &&
          "Expected inlined-at fields to agree");
   return new (Allocator) SDDbgValue(Var, Expr, FI, Off, DL, O);
 }
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 626101bcf60..037bcb485e2 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4641,9 +4641,7 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
     MDLocalVariable *Variable = DI.getVariable();
     MDExpression *Expression = DI.getExpression();
     const Value *Address = DI.getAddress();
-    DIVariable DIVar(Variable);
-    assert((!DIVar || DIVar.isVariable()) &&
-      "Variable in DbgDeclareInst should be either null or a DIVariable.");
+    DIVariable DIVar = Variable;
     if (!Address || !DIVar) {
       DEBUG(dbgs() << "Dropping debug info for " << DI << "\n");
       return nullptr;
@@ -4721,9 +4719,7 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
   }
   case Intrinsic::dbg_value: {
     const DbgValueInst &DI = cast<DbgValueInst>(I);
-    DIVariable DIVar(DI.getVariable());
-    assert((!DIVar || DIVar.isVariable()) &&
-      "Variable in DbgValueInst should be either null or a DIVariable.");
+    DIVariable DIVar = DI.getVariable();
     if (!DIVar)
       return nullptr;
 
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index c56b5f46a53..46a5df3d37f 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -504,7 +504,7 @@ bool SelectionDAGISel::runOnMachineFunction(MachineFunction &mf) {
       DebugLoc DL = MI->getDebugLoc();
       bool IsIndirect = MI->isIndirectDebugValue();
       unsigned Offset = IsIndirect ? MI->getOperand(1).getImm() : 0;
-      assert(DIVariable(Variable)->isValidLocationForIntrinsic(DL) &&
+      assert(cast<MDLocalVariable>(Variable)->isValidLocationForIntrinsic(DL) &&
              "Expected inlined-at fields to agree");
       // Def is never a terminator here, so it is ok to increment InsertPos.
       BuildMI(*EntryMBB, ++InsertPos, DL, TII->get(TargetOpcode::DBG_VALUE),
diff --git a/lib/CodeGen/StackColoring.cpp b/lib/CodeGen/StackColoring.cpp
index 75728033050..2bf2d642e1c 100644
--- a/lib/CodeGen/StackColoring.cpp
+++ b/lib/CodeGen/StackColoring.cpp
@@ -464,7 +464,7 @@ void StackColoring::remapInstructions(DenseMap<int, int> &SlotRemap) {
       continue;
     if (SlotRemap.count(VI.Slot)) {
       DEBUG(dbgs() << "Remapping debug info for ["
-                   << DIVariable(VI.Var).getName() << "].\n");
+                   << cast<MDLocalVariable>(VI.Var)->getName() << "].\n");
       VI.Slot = SlotRemap[VI.Slot];
       FixedDbg++;
     }
diff --git a/lib/Target/AArch64/AArch64AsmPrinter.cpp b/lib/Target/AArch64/AArch64AsmPrinter.cpp
index 1b4483a5d8a..6896bcd701f 100644
--- a/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -371,7 +371,7 @@ void AArch64AsmPrinter::PrintDebugValueComment(const MachineInstr *MI,
   assert(NOps == 4);
   OS << '\t' << MAI->getCommentString() << "DEBUG_VALUE: ";
   // cast away const; DIetc do not take const operands for some reason.
-  DIVariable V(const_cast<MDNode *>(MI->getOperand(NOps - 1).getMetadata()));
+  DIVariable V = cast<MDLocalVariable>(MI->getOperand(NOps - 2).getMetadata());
   OS << V.getName();
   OS << " <- ";
   // Frame address.  Currently handles register +- offset only.
diff --git a/lib/Target/NVPTX/NVPTXAsmPrinter.cpp b/lib/Target/NVPTX/NVPTXAsmPrinter.cpp
index e3187a4dd8f..477d3c7a546 100644
--- a/lib/Target/NVPTX/NVPTXAsmPrinter.cpp
+++ b/lib/Target/NVPTX/NVPTXAsmPrinter.cpp
@@ -129,10 +129,7 @@ void NVPTXAsmPrinter::emitLineNumberAsDotLoc(const MachineInstr &MI) {
   if (!curLoc)
     return;
 
-  DIScope Scope(curLoc.getScope());
-
-  assert((!Scope || Scope.isScope()) &&
-    "Scope of a DebugLoc should be null or a DIScope.");
+  DIScope Scope = cast_or_null<MDScope>(curLoc.getScope());
   if (!Scope)
      return;