X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FIR%2FDebugInfo.cpp;h=c5c1115797173dcd36117ba49d27220829c3d652;hb=8ec0aee3b4a0b038732f30226999145d666186f2;hp=2226dd63be654eb8c372d58f4d338dc65233dfb1;hpb=8ceff5c2b2d2dba9ba04d614b9207f8785d8dd83;p=oota-llvm.git

diff --git a/lib/IR/DebugInfo.cpp b/lib/IR/DebugInfo.cpp
index 2226dd63be6..c5c11157971 100644
--- a/lib/IR/DebugInfo.cpp
+++ b/lib/IR/DebugInfo.cpp
@@ -52,7 +52,7 @@ bool DIDescriptor::Verify() const {
           DIImportedEntity(DbgNode).Verify() || DIExpression(DbgNode).Verify());
 }
 
-static Value *getField(const MDNode *DbgNode, unsigned Elt) {
+static Metadata *getField(const MDNode *DbgNode, unsigned Elt) {
   if (!DbgNode || Elt >= DbgNode->getNumOperands())
     return nullptr;
   return DbgNode->getOperand(Elt);
@@ -73,25 +73,17 @@ StringRef DIDescriptor::getStringField(unsigned Elt) const {
 }
 
 uint64_t DIDescriptor::getUInt64Field(unsigned Elt) const {
-  if (!DbgNode)
-    return 0;
-
-  if (Elt < DbgNode->getNumOperands())
-    if (ConstantInt *CI =
-            dyn_cast_or_null<ConstantInt>(DbgNode->getOperand(Elt)))
+  if (auto *C = getConstantField(Elt))
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
       return CI->getZExtValue();
 
   return 0;
 }
 
 int64_t DIDescriptor::getInt64Field(unsigned Elt) const {
-  if (!DbgNode)
-    return 0;
-
-  if (Elt < DbgNode->getNumOperands())
-    if (ConstantInt *CI =
-            dyn_cast_or_null<ConstantInt>(DbgNode->getOperand(Elt)))
-      return CI->getSExtValue();
+  if (auto *C = getConstantField(Elt))
+    if (ConstantInt *CI = dyn_cast<ConstantInt>(C))
+      return CI->getZExtValue();
 
   return 0;
 }
@@ -102,12 +94,7 @@ DIDescriptor DIDescriptor::getDescriptorField(unsigned Elt) const {
 }
 
 GlobalVariable *DIDescriptor::getGlobalVariableField(unsigned Elt) const {
-  if (!DbgNode)
-    return nullptr;
-
-  if (Elt < DbgNode->getNumOperands())
-    return dyn_cast_or_null<GlobalVariable>(DbgNode->getOperand(Elt));
-  return nullptr;
+  return dyn_cast_or_null<GlobalVariable>(getConstantField(Elt));
 }
 
 Constant *DIDescriptor::getConstantField(unsigned Elt) const {
@@ -115,17 +102,14 @@ Constant *DIDescriptor::getConstantField(unsigned Elt) const {
     return nullptr;
 
   if (Elt < DbgNode->getNumOperands())
-    return dyn_cast_or_null<Constant>(DbgNode->getOperand(Elt));
+    if (auto *C =
+            dyn_cast_or_null<ConstantAsMetadata>(DbgNode->getOperand(Elt)))
+      return C->getValue();
   return nullptr;
 }
 
 Function *DIDescriptor::getFunctionField(unsigned Elt) const {
-  if (!DbgNode)
-    return nullptr;
-
-  if (Elt < DbgNode->getNumOperands())
-    return dyn_cast_or_null<Function>(DbgNode->getOperand(Elt));
-  return nullptr;
+  return dyn_cast_or_null<Function>(getConstantField(Elt));
 }
 
 void DIDescriptor::replaceFunctionField(unsigned Elt, Function *F) {
@@ -134,14 +118,16 @@ void DIDescriptor::replaceFunctionField(unsigned Elt, Function *F) {
 
   if (Elt < DbgNode->getNumOperands()) {
     MDNode *Node = const_cast<MDNode *>(DbgNode);
-    Node->replaceOperandWith(Elt, F);
+    Node->replaceOperandWith(Elt, F ? ConstantAsMetadata::get(F) : nullptr);
   }
 }
 
-/// getInlinedAt - If this variable is inlined then return inline location.
-MDNode *DIVariable::getInlinedAt() const { return getNodeField(DbgNode, 7); }
+static unsigned DIVariableInlinedAtIndex = 4;
+MDNode *DIVariable::getInlinedAt() const {
+  return getNodeField(DbgNode, DIVariableInlinedAtIndex);
+}
 
-/// Return the size reported by the variable's type.
+/// \brief Return the size reported by the variable's type.
 unsigned DIVariable::getSizeInBits(const DITypeIdentifierMap &Map) {
   DIType Ty = getType().resolve(Map);
   // Follow derived types until we reach a type that
@@ -156,12 +142,9 @@ unsigned DIVariable::getSizeInBits(const DITypeIdentifierMap &Map) {
 
 uint64_t DIExpression::getElement(unsigned Idx) const {
   unsigned I = Idx + 1;
-  if (I < DbgNode->getNumOperands())
-    if (auto *CI = dyn_cast_or_null<ConstantInt>(DbgNode->getOperand(I)))
-      return CI->getZExtValue();
-
-  assert(false && "non-existing complex address element requested");
-  return 0;
+  assert(I < getNumHeaderFields() &&
+         "non-existing complex address element requested");
+  return getHeaderFieldAs<int64_t>(I);
 }
 
 bool DIExpression::isVariablePiece() const {
@@ -183,11 +166,9 @@ uint64_t DIExpression::getPieceSize() const {
 //===----------------------------------------------------------------------===//
 
 bool DIDescriptor::isSubroutineType() const {
-  return isCompositeType() && getTag() == dwarf::DW_TAG_subroutine_type;
+  return DbgNode && getTag() == dwarf::DW_TAG_subroutine_type;
 }
 
-/// isBasicType - Return true if the specified tag is legal for
-/// DIBasicType.
 bool DIDescriptor::isBasicType() const {
   if (!DbgNode)
     return false;
@@ -200,7 +181,6 @@ bool DIDescriptor::isBasicType() const {
   }
 }
 
-/// isDerivedType - Return true if the specified tag is legal for DIDerivedType.
 bool DIDescriptor::isDerivedType() const {
   if (!DbgNode)
     return false;
@@ -223,8 +203,6 @@ bool DIDescriptor::isDerivedType() const {
   }
 }
 
-/// isCompositeType - Return true if the specified tag is legal for
-/// DICompositeType.
 bool DIDescriptor::isCompositeType() const {
   if (!DbgNode)
     return false;
@@ -241,7 +219,6 @@ bool DIDescriptor::isCompositeType() const {
   }
 }
 
-/// isVariable - Return true if the specified tag is legal for DIVariable.
 bool DIDescriptor::isVariable() const {
   if (!DbgNode)
     return false;
@@ -254,26 +231,19 @@ bool DIDescriptor::isVariable() const {
   }
 }
 
-/// isType - Return true if the specified tag is legal for DIType.
 bool DIDescriptor::isType() const {
   return isBasicType() || isCompositeType() || isDerivedType();
 }
 
-/// isSubprogram - Return true if the specified tag is legal for
-/// DISubprogram.
 bool DIDescriptor::isSubprogram() const {
   return DbgNode && 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 ||
                      getTag() == dwarf::DW_TAG_constant);
 }
 
-/// isScope - Return true if the specified tag is one of the scope
-/// related tag.
 bool DIDescriptor::isScope() const {
   if (!DbgNode)
     return false;
@@ -290,72 +260,58 @@ bool DIDescriptor::isScope() const {
   return isType();
 }
 
-/// isTemplateTypeParameter - Return true if the specified tag is
-/// DW_TAG_template_type_parameter.
 bool DIDescriptor::isTemplateTypeParameter() const {
   return DbgNode && getTag() == dwarf::DW_TAG_template_type_parameter;
 }
 
-/// isTemplateValueParameter - Return true if the specified tag is
-/// DW_TAG_template_value_parameter.
 bool DIDescriptor::isTemplateValueParameter() const {
   return DbgNode && (getTag() == dwarf::DW_TAG_template_value_parameter ||
                      getTag() == dwarf::DW_TAG_GNU_template_template_param ||
                      getTag() == dwarf::DW_TAG_GNU_template_parameter_pack);
 }
 
-/// isCompileUnit - Return true if the specified tag is DW_TAG_compile_unit.
 bool DIDescriptor::isCompileUnit() const {
   return DbgNode && getTag() == dwarf::DW_TAG_compile_unit;
 }
 
-/// isFile - Return true if the specified tag is DW_TAG_file_type.
 bool DIDescriptor::isFile() const {
   return DbgNode && getTag() == dwarf::DW_TAG_file_type;
 }
 
-/// isNameSpace - Return true if the specified tag is DW_TAG_namespace.
 bool DIDescriptor::isNameSpace() const {
   return DbgNode && getTag() == dwarf::DW_TAG_namespace;
 }
 
-/// isLexicalBlockFile - Return true if the specified descriptor is a
-/// lexical block with an extra file.
 bool DIDescriptor::isLexicalBlockFile() const {
   return DbgNode && getTag() == dwarf::DW_TAG_lexical_block &&
-         (DbgNode->getNumOperands() == 4);
+         DbgNode->getNumOperands() == 3 && getNumHeaderFields() == 2;
 }
 
-/// isLexicalBlock - Return true if the specified tag is DW_TAG_lexical_block.
 bool DIDescriptor::isLexicalBlock() const {
+  // FIXME: There are always exactly 4 header fields in DILexicalBlock, but
+  // something relies on this returning true for DILexicalBlockFile.
   return DbgNode && getTag() == dwarf::DW_TAG_lexical_block &&
-         (DbgNode->getNumOperands() > 3);
+         DbgNode->getNumOperands() == 3 &&
+         (getNumHeaderFields() == 2 || getNumHeaderFields() == 4);
 }
 
-/// isSubrange - Return true if the specified tag is DW_TAG_subrange_type.
 bool DIDescriptor::isSubrange() const {
   return DbgNode && 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;
 }
 
-/// isObjCProperty - Return true if the specified tag is DW_TAG_APPLE_property.
 bool DIDescriptor::isObjCProperty() const {
   return DbgNode && getTag() == dwarf::DW_TAG_APPLE_property;
 }
 
-/// \brief Return true if the specified tag is DW_TAG_imported_module or
-/// DW_TAG_imported_declaration.
 bool DIDescriptor::isImportedEntity() const {
   return DbgNode && (getTag() == dwarf::DW_TAG_imported_module ||
                      getTag() == dwarf::DW_TAG_imported_declaration);
 }
 
-/// \brief Return true if the specified tag is DW_TAG_imported_module or
-/// DW_TAG_imported_declaration.
 bool DIDescriptor::isExpression() const {
   return DbgNode && (getTag() == dwarf::DW_TAG_expression);
 }
@@ -364,8 +320,6 @@ bool DIDescriptor::isExpression() const {
 // Simple Descriptor Constructors and other Methods
 //===----------------------------------------------------------------------===//
 
-/// replaceAllUsesWith - Replace all uses of the MDNode used by this
-/// type with the one in the passed descriptor.
 void DIDescriptor::replaceAllUsesWith(LLVMContext &VMContext, DIDescriptor D) {
 
   assert(DbgNode && "Trying to replace an unverified type!");
@@ -377,33 +331,28 @@ void DIDescriptor::replaceAllUsesWith(LLVMContext &VMContext, DIDescriptor D) {
   // itself.
   const MDNode *DN = D;
   if (DbgNode == DN) {
-    SmallVector<Value*, 10> Ops(DbgNode->getNumOperands());
+    SmallVector<Metadata *, 10> Ops(DbgNode->getNumOperands());
     for (size_t i = 0; i != Ops.size(); ++i)
       Ops[i] = DbgNode->getOperand(i);
     DN = MDNode::get(VMContext, Ops);
   }
 
-  MDNode *Node = const_cast<MDNode *>(DbgNode);
-  const Value *V = cast_or_null<Value>(DN);
-  Node->replaceAllUsesWith(const_cast<Value *>(V));
+  assert(DbgNode->isTemporary() && "Expected temporary node");
+  auto *Node = const_cast<MDNode *>(DbgNode);
+  Node->replaceAllUsesWith(const_cast<MDNode *>(DN));
   MDNode::deleteTemporary(Node);
   DbgNode = DN;
 }
 
-/// replaceAllUsesWith - Replace all uses of the MDNode used by this
-/// type with the one in D.
 void DIDescriptor::replaceAllUsesWith(MDNode *D) {
-
   assert(DbgNode && "Trying to replace an unverified type!");
   assert(DbgNode != D && "This replacement should always happen");
-  MDNode *Node = const_cast<MDNode *>(DbgNode);
-  const MDNode *DN = D;
-  const Value *V = cast_or_null<Value>(DN);
-  Node->replaceAllUsesWith(const_cast<Value *>(V));
+  assert(DbgNode->isTemporary() && "Expected temporary node");
+  auto *Node = const_cast<MDNode *>(DbgNode);
+  Node->replaceAllUsesWith(D);
   MDNode::deleteTemporary(Node);
 }
 
-/// Verify - Verify that a compile unit is well formed.
 bool DICompileUnit::Verify() const {
   if (!isCompileUnit())
     return false;
@@ -413,65 +362,66 @@ bool DICompileUnit::Verify() const {
   if (getFilename().empty())
     return false;
 
-  return DbgNode->getNumOperands() == 14;
+  return DbgNode->getNumOperands() == 7 && getNumHeaderFields() == 8;
 }
 
-/// Verify - Verify that an ObjC property is well formed.
 bool DIObjCProperty::Verify() const {
   if (!isObjCProperty())
     return false;
 
   // Don't worry about the rest of the strings for now.
-  return DbgNode->getNumOperands() == 8;
+  return DbgNode->getNumOperands() == 3 && getNumHeaderFields() == 6;
 }
 
-/// Check if a field at position Elt of a MDNode is a MDNode.
+/// \brief Check if a field at position Elt of a MDNode is a MDNode.
+///
 /// We currently allow an empty string and an integer.
 /// But we don't allow a non-empty string in a MDNode field.
 static bool fieldIsMDNode(const MDNode *DbgNode, unsigned Elt) {
   // FIXME: This function should return true, if the field is null or the field
   // is indeed a MDNode: return !Fld || isa<MDNode>(Fld).
-  Value *Fld = getField(DbgNode, Elt);
+  Metadata *Fld = getField(DbgNode, Elt);
   if (Fld && isa<MDString>(Fld) && !cast<MDString>(Fld)->getString().empty())
     return false;
   return true;
 }
 
-/// Check if a field at position Elt of a MDNode is a MDString.
+/// \brief Check if a field at position Elt of a MDNode is a MDString.
 static bool fieldIsMDString(const MDNode *DbgNode, unsigned Elt) {
-  Value *Fld = getField(DbgNode, Elt);
+  Metadata *Fld = getField(DbgNode, Elt);
   return !Fld || isa<MDString>(Fld);
 }
 
-/// Check if a value can be a reference to a type.
-static bool isTypeRef(const Value *Val) {
-  return !Val ||
-         (isa<MDString>(Val) && !cast<MDString>(Val)->getString().empty()) ||
-         (isa<MDNode>(Val) && DIType(cast<MDNode>(Val)).isType());
+/// \brief Check if a value can be a reference to a type.
+static bool isTypeRef(const Metadata *MD) {
+  if (!MD)
+    return true;
+  if (auto *S = dyn_cast<MDString>(MD))
+    return !S->getString().empty();
+  if (auto *N = dyn_cast<MDNode>(MD))
+    return DIType(N).isType();
+  return false;
 }
 
-/// Check if a field at position Elt of a MDNode can be a reference to a type.
+/// \brief Check if referenced field might be a type.
 static bool fieldIsTypeRef(const MDNode *DbgNode, unsigned Elt) {
-  Value *Fld = getField(DbgNode, Elt);
-  return isTypeRef(Fld);
+  return isTypeRef(dyn_cast_or_null<Metadata>(getField(DbgNode, Elt)));
 }
 
-/// Check if a value can be a ScopeRef.
-static bool isScopeRef(const Value *Val) {
-  return !Val ||
-    (isa<MDString>(Val) && !cast<MDString>(Val)->getString().empty()) ||
-    // Not checking for Val->isScope() here, because it would work
-    // only for lexical scopes and not all subclasses of DIScope.
-    isa<MDNode>(Val);
+/// \brief Check if a value can be a ScopeRef.
+static bool isScopeRef(const Metadata *MD) {
+  if (!MD)
+    return true;
+  if (auto *S = dyn_cast<MDString>(MD))
+    return !S->getString().empty();
+  return isa<MDNode>(MD);
 }
 
-/// Check if a field at position Elt of a MDNode can be a ScopeRef.
+/// \brief Check if a field at position Elt of a MDNode can be a ScopeRef.
 static bool fieldIsScopeRef(const MDNode *DbgNode, unsigned Elt) {
-  Value *Fld = getField(DbgNode, Elt);
-  return isScopeRef(Fld);
+  return isScopeRef(dyn_cast_or_null<Metadata>(getField(DbgNode, Elt)));
 }
 
-/// Verify - Verify that a type descriptor is well formed.
 bool DIType::Verify() const {
   if (!isType())
     return false;
@@ -505,89 +455,112 @@ bool DIType::Verify() const {
     return false;
 }
 
-/// Verify - Verify that a basic type descriptor is well formed.
 bool DIBasicType::Verify() const {
-  return isBasicType() && DbgNode->getNumOperands() == 10;
+  return isBasicType() && DbgNode->getNumOperands() == 3 &&
+         getNumHeaderFields() == 8;
 }
 
-/// Verify - Verify that a derived type descriptor is well formed.
 bool DIDerivedType::Verify() const {
-  // Make sure DerivedFrom @ field 9 is TypeRef.
-  if (!fieldIsTypeRef(DbgNode, 9))
+  // Make sure DerivedFrom @ field 3 is TypeRef.
+  if (!fieldIsTypeRef(DbgNode, 3))
     return false;
   if (getTag() == dwarf::DW_TAG_ptr_to_member_type)
-    // Make sure ClassType @ field 10 is a TypeRef.
-    if (!fieldIsTypeRef(DbgNode, 10))
+    // Make sure ClassType @ field 4 is a TypeRef.
+    if (!fieldIsTypeRef(DbgNode, 4))
       return false;
 
-  return isDerivedType() && DbgNode->getNumOperands() >= 10 &&
-         DbgNode->getNumOperands() <= 14;
+  return isDerivedType() && DbgNode->getNumOperands() >= 4 &&
+         DbgNode->getNumOperands() <= 8 && getNumHeaderFields() >= 7 &&
+         getNumHeaderFields() <= 8;
 }
 
-/// Verify - Verify that a composite type descriptor is well formed.
 bool DICompositeType::Verify() const {
   if (!isCompositeType())
     return false;
 
-  // Make sure DerivedFrom @ field 9 and ContainingType @ field 12 are TypeRef.
-  if (!fieldIsTypeRef(DbgNode, 9))
+  // Make sure DerivedFrom @ field 3 and ContainingType @ field 5 are TypeRef.
+  if (!fieldIsTypeRef(DbgNode, 3))
     return false;
-  if (!fieldIsTypeRef(DbgNode, 12))
+  if (!fieldIsTypeRef(DbgNode, 5))
     return false;
 
-  // Make sure the type identifier at field 14 is MDString, it can be null.
-  if (!fieldIsMDString(DbgNode, 14))
+  // Make sure the type identifier at field 7 is MDString, it can be null.
+  if (!fieldIsMDString(DbgNode, 7))
     return false;
 
   // A subroutine type can't be both & and &&.
   if (isLValueReference() && isRValueReference())
     return false;
 
-  return DbgNode->getNumOperands() == 15;
+  return DbgNode->getNumOperands() == 8 && getNumHeaderFields() == 8;
 }
 
-/// Verify - Verify that a subprogram descriptor is well formed.
 bool DISubprogram::Verify() const {
   if (!isSubprogram())
     return false;
 
-  // Make sure context @ field 2 is a ScopeRef and type @ field 7 is a MDNode.
+  // Make sure context @ field 2 is a ScopeRef and type @ field 3 is a MDNode.
   if (!fieldIsScopeRef(DbgNode, 2))
     return false;
-  if (!fieldIsMDNode(DbgNode, 7))
+  if (!fieldIsMDNode(DbgNode, 3))
     return false;
-  // Containing type @ field 12.
-  if (!fieldIsTypeRef(DbgNode, 12))
+  // Containing type @ field 4.
+  if (!fieldIsTypeRef(DbgNode, 4))
     return false;
 
   // A subprogram can't be both & and &&.
   if (isLValueReference() && isRValueReference())
     return false;
 
-  return DbgNode->getNumOperands() == 20;
+  // If a DISubprogram has an llvm::Function*, then scope chains from all
+  // instructions within the function should lead to this DISubprogram.
+  if (auto *F = getFunction()) {
+    for (auto &BB : *F) {
+      for (auto &I : BB) {
+        DebugLoc DL = I.getDebugLoc();
+        if (DL.isUnknown())
+          continue;
+
+        MDNode *Scope = nullptr;
+        MDNode *IA = nullptr;
+        // walk the inlined-at scopes
+        while ((IA = DL.getInlinedAt()))
+          DL = DebugLoc::getFromDILocation(IA);
+        DL.getScopeAndInlinedAt(Scope, IA);
+        assert(!IA);
+        while (!DIDescriptor(Scope).isSubprogram()) {
+          DILexicalBlockFile D(Scope);
+          Scope = D.isLexicalBlockFile()
+                      ? D.getScope()
+                      : DebugLoc::getFromDILexicalBlock(Scope).getScope();
+        }
+        if (!DISubprogram(Scope).describes(F))
+          return false;
+      }
+    }
+  }
+  return DbgNode->getNumOperands() == 9 && getNumHeaderFields() == 12;
 }
 
-/// Verify - Verify that a global variable descriptor is well formed.
 bool DIGlobalVariable::Verify() const {
   if (!isGlobalVariable())
     return false;
 
   if (getDisplayName().empty())
     return false;
-  // Make sure context @ field 2 is an MDNode.
-  if (!fieldIsMDNode(DbgNode, 2))
+  // Make sure context @ field 1 is an MDNode.
+  if (!fieldIsMDNode(DbgNode, 1))
     return false;
-  // Make sure that type @ field 8 is a DITypeRef.
-  if (!fieldIsTypeRef(DbgNode, 8))
+  // Make sure that type @ field 3 is a DITypeRef.
+  if (!fieldIsTypeRef(DbgNode, 3))
     return false;
-  // Make sure StaticDataMemberDeclaration @ field 12 is MDNode.
-  if (!fieldIsMDNode(DbgNode, 12))
+  // Make sure StaticDataMemberDeclaration @ field 5 is MDNode.
+  if (!fieldIsMDNode(DbgNode, 5))
     return false;
 
-  return DbgNode->getNumOperands() == 13;
+  return DbgNode->getNumOperands() == 6 && getNumHeaderFields() == 7;
 }
 
-/// Verify - Verify that a variable descriptor is well formed.
 bool DIVariable::Verify() const {
   if (!isVariable())
     return false;
@@ -595,127 +568,120 @@ bool DIVariable::Verify() const {
   // Make sure context @ field 1 is an MDNode.
   if (!fieldIsMDNode(DbgNode, 1))
     return false;
-  // Make sure that type @ field 5 is a DITypeRef.
-  if (!fieldIsTypeRef(DbgNode, 5))
+  // Make sure that type @ field 3 is a DITypeRef.
+  if (!fieldIsTypeRef(DbgNode, 3))
+    return false;
+
+  // Check the number of header fields, which is common between complex and
+  // simple variables.
+  if (getNumHeaderFields() != 4)
     return false;
 
   // Variable without an inline location.
-  if (DbgNode->getNumOperands() == 7)
+  if (DbgNode->getNumOperands() == 4)
     return true;
 
-  return DbgNode->getNumOperands() == 8;
+  // Variable with an inline location.
+  return getInlinedAt() != nullptr && DbgNode->getNumOperands() == 5;
 }
 
-/// Verify - Verify that a variable descriptor is well formed.
 bool DIExpression::Verify() const {
   // Empty DIExpressions may be represented as a nullptr.
   if (!DbgNode)
     return true;
 
-  return isExpression();
+  return isExpression() && DbgNode->getNumOperands() == 1;
 }
 
-/// Verify - Verify that a location descriptor is well formed.
 bool DILocation::Verify() const {
-  if (!DbgNode)
-    return false;
-
-  return DbgNode->getNumOperands() == 4;
+  return DbgNode && isa<MDLocation>(DbgNode);
 }
 
-/// Verify - Verify that a namespace descriptor is well formed.
 bool DINameSpace::Verify() const {
   if (!isNameSpace())
     return false;
-  return DbgNode->getNumOperands() == 5;
+  return DbgNode->getNumOperands() == 3 && getNumHeaderFields() == 3;
 }
 
-/// \brief Retrieve the MDNode for the directory/file pair.
 MDNode *DIFile::getFileNode() const { return getNodeField(DbgNode, 1); }
 
-/// \brief Verify that the file descriptor is well formed.
 bool DIFile::Verify() const {
   return isFile() && DbgNode->getNumOperands() == 2;
 }
 
-/// \brief Verify that the enumerator descriptor is well formed.
 bool DIEnumerator::Verify() const {
-  return isEnumerator() && DbgNode->getNumOperands() == 3;
+  return isEnumerator() && DbgNode->getNumOperands() == 1 &&
+         getNumHeaderFields() == 3;
 }
 
-/// \brief Verify that the subrange descriptor is well formed.
 bool DISubrange::Verify() const {
-  return isSubrange() && DbgNode->getNumOperands() == 3;
+  return isSubrange() && DbgNode->getNumOperands() == 1 &&
+         getNumHeaderFields() == 3;
 }
 
-/// \brief Verify that the lexical block descriptor is well formed.
 bool DILexicalBlock::Verify() const {
-  return isLexicalBlock() && DbgNode->getNumOperands() == 6;
+  return isLexicalBlock() && DbgNode->getNumOperands() == 3 &&
+         getNumHeaderFields() == 4;
 }
 
-/// \brief Verify that the file-scoped lexical block descriptor is well formed.
 bool DILexicalBlockFile::Verify() const {
-  return isLexicalBlockFile() && DbgNode->getNumOperands() == 4;
+  return isLexicalBlockFile() && DbgNode->getNumOperands() == 3 &&
+         getNumHeaderFields() == 2;
 }
 
-/// \brief Verify that the template type parameter descriptor is well formed.
 bool DITemplateTypeParameter::Verify() const {
-  return isTemplateTypeParameter() && DbgNode->getNumOperands() == 7;
+  return isTemplateTypeParameter() && DbgNode->getNumOperands() == 4 &&
+         getNumHeaderFields() == 4;
 }
 
-/// \brief Verify that the template value parameter descriptor is well formed.
 bool DITemplateValueParameter::Verify() const {
-  return isTemplateValueParameter() && DbgNode->getNumOperands() == 8;
+  return isTemplateValueParameter() && DbgNode->getNumOperands() == 5 &&
+         getNumHeaderFields() == 4;
 }
 
-/// \brief Verify that the imported module descriptor is well formed.
 bool DIImportedEntity::Verify() const {
-  return isImportedEntity() &&
-         (DbgNode->getNumOperands() == 4 || DbgNode->getNumOperands() == 5);
+  return isImportedEntity() && DbgNode->getNumOperands() == 3 &&
+         getNumHeaderFields() == 3;
 }
 
-/// getObjCProperty - Return property node, if this ivar is associated with one.
 MDNode *DIDerivedType::getObjCProperty() const {
-  return getNodeField(DbgNode, 10);
+  return getNodeField(DbgNode, 4);
 }
 
 MDString *DICompositeType::getIdentifier() const {
-  return cast_or_null<MDString>(getField(DbgNode, 14));
+  return cast_or_null<MDString>(getField(DbgNode, 7));
 }
 
 #ifndef NDEBUG
 static void VerifySubsetOf(const MDNode *LHS, const MDNode *RHS) {
   for (unsigned i = 0; i != LHS->getNumOperands(); ++i) {
     // Skip the 'empty' list (that's a single i32 0, rather than truly empty).
-    if (i == 0 && isa<ConstantInt>(LHS->getOperand(i)))
+    if (i == 0 && mdconst::hasa<ConstantInt>(LHS->getOperand(i)))
       continue;
     const MDNode *E = cast<MDNode>(LHS->getOperand(i));
     bool found = false;
     for (unsigned j = 0; !found && j != RHS->getNumOperands(); ++j)
-      found = E == RHS->getOperand(j);
+      found = (E == cast<MDNode>(RHS->getOperand(j)));
     assert(found && "Losing a member during member list replacement");
   }
 }
 #endif
 
-/// \brief Set the array of member DITypes.
 void DICompositeType::setArraysHelper(MDNode *Elements, MDNode *TParams) {
-  TrackingVH<MDNode> N(*this);
+  TrackingMDNodeRef N(*this);
   if (Elements) {
 #ifndef NDEBUG
     // Check that the new list of members contains all the old members as well.
-    if (const MDNode *El = cast_or_null<MDNode>(N->getOperand(10)))
+    if (const MDNode *El = cast_or_null<MDNode>(N->getOperand(4)))
       VerifySubsetOf(El, Elements);
 #endif
-    N->replaceOperandWith(10, Elements);
+    N->replaceOperandWith(4, Elements);
   }
   if (TParams)
-    N->replaceOperandWith(13, TParams);
+    N->replaceOperandWith(6, TParams);
   DbgNode = N;
 }
 
-/// Generate a reference to this DIType. Uses the type identifier instead
-/// of the actual MDNode if possible, to help type uniquing.
 DIScopeRef DIScope::getRef() const {
   if (!isCompositeType())
     return DIScopeRef(*this);
@@ -725,15 +691,12 @@ DIScopeRef DIScope::getRef() const {
   return DIScopeRef(DTy.getIdentifier());
 }
 
-/// \brief Set the containing type.
 void DICompositeType::setContainingType(DICompositeType ContainingType) {
-  TrackingVH<MDNode> N(*this);
-  N->replaceOperandWith(12, ContainingType.getRef());
+  TrackingMDNodeRef N(*this);
+  N->replaceOperandWith(5, ContainingType.getRef());
   DbgNode = N;
 }
 
-/// isInlinedFnArgument - Return true if this variable provides debugging
-/// information for an inlined function arguments.
 bool DIVariable::isInlinedFnArgument(const Function *CurFn) {
   assert(CurFn && "Invalid function");
   if (!getContext().isSubprogram())
@@ -743,8 +706,6 @@ bool DIVariable::isInlinedFnArgument(const Function *CurFn) {
   return !DISubprogram(getContext()).describes(CurFn);
 }
 
-/// describes - Return true if this subprogram provides debugging
-/// information for the function F.
 bool DISubprogram::describes(const Function *F) {
   assert(F && "Invalid function");
   if (F == getFunction())
@@ -757,27 +718,18 @@ bool DISubprogram::describes(const Function *F) {
   return false;
 }
 
-unsigned DISubprogram::isOptimized() const {
-  assert(DbgNode && "Invalid subprogram descriptor!");
-  if (DbgNode->getNumOperands() == 15)
-    return getUnsignedField(14);
-  return 0;
-}
-
 MDNode *DISubprogram::getVariablesNodes() const {
-  return getNodeField(DbgNode, 18);
+  return getNodeField(DbgNode, 8);
 }
 
 DIArray DISubprogram::getVariables() const {
-  return DIArray(getNodeField(DbgNode, 18));
+  return DIArray(getNodeField(DbgNode, 8));
 }
 
-Value *DITemplateValueParameter::getValue() const {
-  return getField(DbgNode, 4);
+Metadata *DITemplateValueParameter::getValue() const {
+  return DbgNode->getOperand(3);
 }
 
-// If the current node has a parent scope then return that,
-// else return an empty scope.
 DIScopeRef DIScope::getContext() const {
 
   if (isType())
@@ -799,7 +751,6 @@ DIScopeRef DIScope::getContext() const {
   return DIScopeRef(nullptr);
 }
 
-// If the scope node has a name, return that, else return an empty string.
 StringRef DIScope::getName() const {
   if (isType())
     return DIType(DbgNode).getName();
@@ -826,128 +777,103 @@ StringRef DIScope::getDirectory() const {
 }
 
 DIArray DICompileUnit::getEnumTypes() const {
-  if (!DbgNode || DbgNode->getNumOperands() < 13)
+  if (!DbgNode || DbgNode->getNumOperands() < 7)
     return DIArray();
 
-  return DIArray(getNodeField(DbgNode, 7));
+  return DIArray(getNodeField(DbgNode, 2));
 }
 
 DIArray DICompileUnit::getRetainedTypes() const {
-  if (!DbgNode || DbgNode->getNumOperands() < 13)
+  if (!DbgNode || DbgNode->getNumOperands() < 7)
     return DIArray();
 
-  return DIArray(getNodeField(DbgNode, 8));
+  return DIArray(getNodeField(DbgNode, 3));
 }
 
 DIArray DICompileUnit::getSubprograms() const {
-  if (!DbgNode || DbgNode->getNumOperands() < 13)
+  if (!DbgNode || DbgNode->getNumOperands() < 7)
     return DIArray();
 
-  return DIArray(getNodeField(DbgNode, 9));
+  return DIArray(getNodeField(DbgNode, 4));
 }
 
 DIArray DICompileUnit::getGlobalVariables() const {
-  if (!DbgNode || DbgNode->getNumOperands() < 13)
+  if (!DbgNode || DbgNode->getNumOperands() < 7)
     return DIArray();
 
-  return DIArray(getNodeField(DbgNode, 10));
+  return DIArray(getNodeField(DbgNode, 5));
 }
 
 DIArray DICompileUnit::getImportedEntities() const {
-  if (!DbgNode || DbgNode->getNumOperands() < 13)
+  if (!DbgNode || DbgNode->getNumOperands() < 7)
     return DIArray();
 
-  return DIArray(getNodeField(DbgNode, 11));
+  return DIArray(getNodeField(DbgNode, 6));
+}
+
+void DICompileUnit::replaceSubprograms(DIArray Subprograms) {
+  assert(Verify() && "Expected compile unit");
+  if (Subprograms == getSubprograms())
+    return;
+
+  const_cast<MDNode *>(DbgNode)->replaceOperandWith(4, Subprograms);
+}
+
+void DICompileUnit::replaceGlobalVariables(DIArray GlobalVariables) {
+  assert(Verify() && "Expected compile unit");
+  if (GlobalVariables == getGlobalVariables())
+    return;
+
+  const_cast<MDNode *>(DbgNode)->replaceOperandWith(5, GlobalVariables);
 }
 
-/// copyWithNewScope - Return a copy of this location, replacing the
-/// current scope with the given one.
 DILocation DILocation::copyWithNewScope(LLVMContext &Ctx,
                                         DILexicalBlockFile NewScope) {
-  SmallVector<Value *, 10> Elts;
   assert(Verify());
-  for (unsigned I = 0; I < DbgNode->getNumOperands(); ++I) {
-    if (I != 2)
-      Elts.push_back(DbgNode->getOperand(I));
-    else
-      Elts.push_back(NewScope);
-  }
-  MDNode *NewDIL = MDNode::get(Ctx, Elts);
-  return DILocation(NewDIL);
+  assert(NewScope && "Expected valid scope");
+
+  const auto *Old = cast<MDLocation>(DbgNode);
+  return DILocation(MDLocation::get(Ctx, Old->getLine(), Old->getColumn(),
+                                    NewScope, Old->getInlinedAt()));
 }
 
-/// computeNewDiscriminator - Generate a new discriminator value for this
-/// file and line location.
 unsigned DILocation::computeNewDiscriminator(LLVMContext &Ctx) {
   std::pair<const char *, unsigned> Key(getFilename().data(), getLineNumber());
   return ++Ctx.pImpl->DiscriminatorTable[Key];
 }
 
-/// fixupSubprogramName - Replace contains special characters used
-/// in a typical Objective-C names with '.' in a given string.
-static void fixupSubprogramName(DISubprogram Fn, SmallVectorImpl<char> &Out) {
-  StringRef FName =
-      Fn.getFunction() ? Fn.getFunction()->getName() : Fn.getName();
-  FName = Function::getRealLinkageName(FName);
-
-  StringRef Prefix("llvm.dbg.lv.");
-  Out.reserve(FName.size() + Prefix.size());
-  Out.append(Prefix.begin(), Prefix.end());
-
-  bool isObjCLike = false;
-  for (size_t i = 0, e = FName.size(); i < e; ++i) {
-    char C = FName[i];
-    if (C == '[')
-      isObjCLike = true;
-
-    if (isObjCLike && (C == '[' || C == ']' || C == ' ' || C == ':' ||
-                       C == '+' || C == '(' || C == ')'))
-      Out.push_back('.');
-    else
-      Out.push_back(C);
-  }
-}
-
-/// getFnSpecificMDNode - Return a NameMDNode, if available, that is
-/// suitable to hold function specific information.
-NamedMDNode *llvm::getFnSpecificMDNode(const Module &M, DISubprogram Fn) {
-  SmallString<32> Name;
-  fixupSubprogramName(Fn, Name);
-  return M.getNamedMetadata(Name.str());
-}
-
-/// getOrInsertFnSpecificMDNode - Return a NameMDNode that is suitable
-/// to hold function specific information.
-NamedMDNode *llvm::getOrInsertFnSpecificMDNode(Module &M, DISubprogram Fn) {
-  SmallString<32> Name;
-  fixupSubprogramName(Fn, Name);
-  return M.getOrInsertNamedMetadata(Name.str());
-}
-
-/// createInlinedVariable - Create a new inlined variable based on current
-/// variable.
-/// @param DV            Current Variable.
-/// @param InlinedScope  Location at current variable is inlined.
 DIVariable llvm::createInlinedVariable(MDNode *DV, MDNode *InlinedScope,
                                        LLVMContext &VMContext) {
-  SmallVector<Value *, 16> Elts;
-  // Insert inlined scope as 7th element.
-  for (unsigned i = 0, e = DV->getNumOperands(); i != e; ++i)
-    i == 7 ? Elts.push_back(InlinedScope) : Elts.push_back(DV->getOperand(i));
-  return DIVariable(MDNode::get(VMContext, Elts));
+  assert(DIVariable(DV).Verify() && "Expected a DIVariable");
+  if (!InlinedScope)
+    return cleanseInlinedVariable(DV, VMContext);
+
+  // Insert inlined scope.
+  SmallVector<Metadata *, 8> Elts;
+  for (unsigned I = 0, E = DIVariableInlinedAtIndex; I != E; ++I)
+    Elts.push_back(DV->getOperand(I));
+  Elts.push_back(InlinedScope);
+
+  DIVariable Inlined(MDNode::get(VMContext, Elts));
+  assert(Inlined.Verify() && "Expected to create a DIVariable");
+  return Inlined;
 }
 
-/// cleanseInlinedVariable - Remove inlined scope from the variable.
 DIVariable llvm::cleanseInlinedVariable(MDNode *DV, LLVMContext &VMContext) {
-  SmallVector<Value *, 16> Elts;
-  // Insert inlined scope as 7th element.
-  for (unsigned i = 0, e = DV->getNumOperands(); i != e; ++i)
-    i == 7 ? Elts.push_back(Constant::getNullValue(Type::getInt32Ty(VMContext)))
-           : Elts.push_back(DV->getOperand(i));
-  return DIVariable(MDNode::get(VMContext, Elts));
+  assert(DIVariable(DV).Verify() && "Expected a DIVariable");
+  if (!DIVariable(DV).getInlinedAt())
+    return DIVariable(DV);
+
+  // Remove inlined scope.
+  SmallVector<Metadata *, 8> Elts;
+  for (unsigned I = 0, E = DIVariableInlinedAtIndex; I != E; ++I)
+    Elts.push_back(DV->getOperand(I));
+
+  DIVariable Cleansed(MDNode::get(VMContext, Elts));
+  assert(Cleansed.Verify() && "Expected to create a DIVariable");
+  return Cleansed;
 }
 
-/// getDISubprogram - Find subprogram that is enclosing this scope.
 DISubprogram llvm::getDISubprogram(const MDNode *Scope) {
   DIDescriptor D(Scope);
   if (D.isSubprogram())
@@ -962,7 +888,23 @@ DISubprogram llvm::getDISubprogram(const MDNode *Scope) {
   return DISubprogram();
 }
 
-/// getDICompositeType - Find underlying composite type.
+DISubprogram llvm::getDISubprogram(const Function *F) {
+  // We look for the first instr that has a debug annotation leading back to F.
+  for (auto &BB : *F) {
+    auto Inst = std::find_if(BB.begin(), BB.end(), [](const Instruction &Inst) {
+      return !Inst.getDebugLoc().isUnknown();
+    });
+    if (Inst == BB.end())
+      continue;
+    DebugLoc DLoc = Inst->getDebugLoc();
+    const MDNode *Scope = DLoc.getScopeNode();
+    DISubprogram Subprogram = getDISubprogram(Scope);
+    return Subprogram.describes(F) ? Subprogram : DISubprogram();
+  }
+
+  return DISubprogram();
+}
+
 DICompositeType llvm::getDICompositeType(DIType T) {
   if (T.isCompositeType())
     return DICompositeType(T);
@@ -979,7 +921,6 @@ DICompositeType llvm::getDICompositeType(DIType T) {
   return DICompositeType();
 }
 
-/// Update DITypeIdentifierMap by going through retained types of each CU.
 DITypeIdentifierMap
 llvm::generateDITypeIdentifierMap(const NamedMDNode *CU_Nodes) {
   DITypeIdentifierMap Map;
@@ -1028,7 +969,6 @@ void DebugInfoFinder::InitializeTypeMap(const Module &M) {
     }
 }
 
-/// processModule - Process entire module and collect debug info.
 void DebugInfoFinder::processModule(const Module &M) {
   InitializeTypeMap(M);
   if (NamedMDNode *CU_Nodes = M.getNamedMetadata("llvm.dbg.cu")) {
@@ -1067,7 +1007,6 @@ void DebugInfoFinder::processModule(const Module &M) {
   }
 }
 
-/// processLocation - Process DILocation.
 void DebugInfoFinder::processLocation(const Module &M, DILocation Loc) {
   if (!Loc)
     return;
@@ -1076,7 +1015,6 @@ void DebugInfoFinder::processLocation(const Module &M, DILocation Loc) {
   processLocation(M, Loc.getOrigLocation());
 }
 
-/// processType - Process DIType.
 void DebugInfoFinder::processType(DIType DT) {
   if (!addType(DT))
     return;
@@ -1132,7 +1070,6 @@ void DebugInfoFinder::processScope(DIScope Scope) {
   }
 }
 
-/// processSubprogram - Process DISubprogram.
 void DebugInfoFinder::processSubprogram(DISubprogram SP) {
   if (!addSubprogram(SP))
     return;
@@ -1153,7 +1090,6 @@ void DebugInfoFinder::processSubprogram(DISubprogram SP) {
   }
 }
 
-/// processDeclare - Process DbgDeclareInst.
 void DebugInfoFinder::processDeclare(const Module &M,
                                      const DbgDeclareInst *DDI) {
   MDNode *N = dyn_cast<MDNode>(DDI->getVariable());
@@ -1165,7 +1101,7 @@ void DebugInfoFinder::processDeclare(const Module &M,
   if (!DV.isVariable())
     return;
 
-  if (!NodesSeen.insert(DV))
+  if (!NodesSeen.insert(DV).second)
     return;
   processScope(DIVariable(N).getContext());
   processType(DIVariable(N).getType().resolve(TypeIdentifierMap));
@@ -1181,53 +1117,49 @@ void DebugInfoFinder::processValue(const Module &M, const DbgValueInst *DVI) {
   if (!DV.isVariable())
     return;
 
-  if (!NodesSeen.insert(DV))
+  if (!NodesSeen.insert(DV).second)
     return;
   processScope(DIVariable(N).getContext());
   processType(DIVariable(N).getType().resolve(TypeIdentifierMap));
 }
 
-/// addType - Add type into Tys.
 bool DebugInfoFinder::addType(DIType DT) {
   if (!DT)
     return false;
 
-  if (!NodesSeen.insert(DT))
+  if (!NodesSeen.insert(DT).second)
     return false;
 
   TYs.push_back(DT);
   return true;
 }
 
-/// addCompileUnit - Add compile unit into CUs.
 bool DebugInfoFinder::addCompileUnit(DICompileUnit CU) {
   if (!CU)
     return false;
-  if (!NodesSeen.insert(CU))
+  if (!NodesSeen.insert(CU).second)
     return false;
 
   CUs.push_back(CU);
   return true;
 }
 
-/// addGlobalVariable - Add global variable into GVs.
 bool DebugInfoFinder::addGlobalVariable(DIGlobalVariable DIG) {
   if (!DIG)
     return false;
 
-  if (!NodesSeen.insert(DIG))
+  if (!NodesSeen.insert(DIG).second)
     return false;
 
   GVs.push_back(DIG);
   return true;
 }
 
-// addSubprogram - Add subprgoram into SPs.
 bool DebugInfoFinder::addSubprogram(DISubprogram SP) {
   if (!SP)
     return false;
 
-  if (!NodesSeen.insert(SP))
+  if (!NodesSeen.insert(SP).second)
     return false;
 
   SPs.push_back(SP);
@@ -1241,7 +1173,7 @@ bool DebugInfoFinder::addScope(DIScope Scope) {
   // as null for now.
   if (Scope->getNumOperands() == 0)
     return false;
-  if (!NodesSeen.insert(Scope))
+  if (!NodesSeen.insert(Scope).second)
     return false;
   Scopes.push_back(Scope);
   return true;
@@ -1251,13 +1183,11 @@ bool DebugInfoFinder::addScope(DIScope Scope) {
 // DIDescriptor: dump routines for all descriptors.
 //===----------------------------------------------------------------------===//
 
-/// dump - Print descriptor to dbgs() with a newline.
 void DIDescriptor::dump() const {
   print(dbgs());
   dbgs() << '\n';
 }
 
-/// print - Print descriptor.
 void DIDescriptor::print(raw_ostream &OS) const {
   if (!DbgNode)
     return;
@@ -1456,9 +1386,12 @@ void DIExpression::printInternal(raw_ostream &OS) const {
     case DW_OP_piece: {
       unsigned Offset = getElement(++I);
       unsigned Size = getElement(++I);
-      OS << " offset=" << Offset << ", size= " << Size;
+      OS << " offset=" << Offset << ", size=" << Size;
       break;
     }
+    case DW_OP_deref:
+      // No arguments.
+      break;
     default:
       // Else bail out early. This may be a line table entry.
       OS << "Unknown]";
@@ -1511,30 +1444,22 @@ void DIVariable::printExtendedName(raw_ostream &OS) const {
   }
 }
 
-/// Specialize constructor to make sure it has the correct type.
-template <> DIRef<DIScope>::DIRef(const Value *V) : Val(V) {
+template <> DIRef<DIScope>::DIRef(const Metadata *V) : Val(V) {
   assert(isScopeRef(V) && "DIScopeRef should be a MDString or MDNode");
 }
-template <> DIRef<DIType>::DIRef(const Value *V) : Val(V) {
+template <> DIRef<DIType>::DIRef(const Metadata *V) : Val(V) {
   assert(isTypeRef(V) && "DITypeRef should be a MDString or MDNode");
 }
 
-/// Specialize getFieldAs to handle fields that are references to DIScopes.
 template <>
 DIScopeRef DIDescriptor::getFieldAs<DIScopeRef>(unsigned Elt) const {
-  return DIScopeRef(getField(DbgNode, Elt));
+  return DIScopeRef(cast_or_null<Metadata>(getField(DbgNode, Elt)));
 }
-/// Specialize getFieldAs to handle fields that are references to DITypes.
 template <> DITypeRef DIDescriptor::getFieldAs<DITypeRef>(unsigned Elt) const {
-  return DITypeRef(getField(DbgNode, Elt));
+  return DITypeRef(cast_or_null<Metadata>(getField(DbgNode, Elt)));
 }
 
-/// Strip debug info in the module if it exists.
-/// To do this, we remove all calls to the debugger intrinsics and any named
-/// metadata for debugging. We also remove debug locations for instructions.
-/// Return true if module is modified.
 bool llvm::StripDebugInfo(Module &M) {
-
   bool Changed = false;
 
   // Remove all of the calls to the debugger intrinsics, and remove them from
@@ -1581,12 +1506,11 @@ bool llvm::StripDebugInfo(Module &M) {
   return Changed;
 }
 
-/// Return Debug Info Metadata Version by checking module flags.
 unsigned llvm::getDebugMetadataVersionFromModule(const Module &M) {
-  Value *Val = M.getModuleFlag("Debug Info Version");
-  if (!Val)
-    return 0;
-  return cast<ConstantInt>(Val)->getZExtValue();
+  if (auto *Val = mdconst::extract_or_null<ConstantInt>(
+          M.getModuleFlag("Debug Info Version")))
+    return Val->getZExtValue();
+  return 0;
 }
 
 llvm::DenseMap<const llvm::Function *, llvm::DISubprogram>