[PDB] Refactor the PDB symbol classes to fix a reuse bug.

The way DIA SDK works is that when you request a symbol, it
gets assigned an internal identifier that is unique for the
life of the session.  You can then use this identifier to
get back the same symbol, with all of the same internal state
that it had before, even if you "destroyed" the original
copy of the object you had.

This didn't work properly in our native implementation, and
if you destroyed an object for a particular symbol, then
requested the same symbol again, it would get assigned a new
ID and you'd get a fresh copy of the object.  In order to fix
this some refactoring had to happen to properly reuse cached
objects.  Some unittests are added to verify that symbol
reuse is taking place, making use of the new unittest input
feature.

llvm-svn: 341503

include/llvm/DebugInfo/PDB/Native/NativeEnumModules.h

@@ -11,18 +11,15 @@
 #define LLVM_DEBUGINFO_PDB_NATIVE_NATIVEENUMMODULES_H
 
 #include "llvm/DebugInfo/PDB/IPDBEnumChildren.h"
-#include "llvm/DebugInfo/PDB/Native/DbiModuleDescriptor.h"
 #include "llvm/DebugInfo/PDB/PDBSymbol.h"
 namespace llvm {
 namespace pdb {
 
-class DbiModuleList;
 class NativeSession;
 
 class NativeEnumModules : public IPDBEnumChildren<PDBSymbol> {
 public:
-  NativeEnumModules(NativeSession &Session, const DbiModuleList &Modules,
-                    uint32_t Index = 0);
+  NativeEnumModules(NativeSession &Session, uint32_t Index = 0);
 
   uint32_t getChildCount() const override;
   std::unique_ptr<PDBSymbol> getChildAtIndex(uint32_t Index) const override;
@@ -32,7 +29,6 @@ public:
 
 private:
   NativeSession &Session;
-  const DbiModuleList &Modules;
   uint32_t Index;
 };
 }

include/llvm/DebugInfo/PDB/Native/NativeExeSymbol.h

@@ -16,6 +16,8 @@
 namespace llvm {
 namespace pdb {
 
+class DbiStream;
+
 class NativeExeSymbol : public NativeRawSymbol {
 public:
   NativeExeSymbol(NativeSession &Session, SymIndexId SymbolId);
@@ -31,8 +33,16 @@ public:
   bool hasCTypes() const override;
   bool hasPrivateSymbols() const override;
 
+  std::unique_ptr<PDBSymbolCompiland> getOrCreateCompiland(uint32_t Index);
+  uint32_t getNumCompilands() const;
+
 private:
   PDBFile &File;
+
+  DbiStream *Dbi = nullptr;
+
+  // EXE symbol is the authority on the various symbol types.
+  mutable std::vector<SymIndexId> Compilands;
 };
 
 } // namespace pdb

include/llvm/DebugInfo/PDB/Native/NativeRawSymbol.h

@@ -23,7 +23,8 @@ typedef uint32_t SymIndexId;
 
 class NativeRawSymbol : public IPDBRawSymbol {
 public:
-  NativeRawSymbol(NativeSession &PDBSession, SymIndexId SymbolId);
+  NativeRawSymbol(NativeSession &PDBSession, PDB_SymType Tag,
+                  SymIndexId SymbolId);
 
   virtual std::unique_ptr<NativeRawSymbol> clone() const = 0;
 
@@ -230,6 +231,7 @@ public:
 
 protected:
   NativeSession &Session;
+  PDB_SymType Tag;
   SymIndexId SymbolId;
 };
 

include/llvm/DebugInfo/PDB/Native/NativeSession.h

@@ -15,7 +15,6 @@
 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
 #include "llvm/DebugInfo/PDB/IPDBRawSymbol.h"
 #include "llvm/DebugInfo/PDB/IPDBSession.h"
-#include "llvm/DebugInfo/PDB/Native/DbiModuleDescriptor.h"
 #include "llvm/DebugInfo/PDB/Native/NativeBuiltinSymbol.h"
 #include "llvm/DebugInfo/PDB/Native/NativeRawSymbol.h"
 #include "llvm/Support/Allocator.h"
@@ -25,6 +24,7 @@ namespace llvm {
 class MemoryBuffer;
 namespace pdb {
 class PDBFile;
+class NativeExeSymbol;
 
 class NativeSession : public IPDBSession {
 public:
@@ -37,8 +37,16 @@ public:
   static Error createFromExe(StringRef Path,
                              std::unique_ptr<IPDBSession> &Session);
 
-  std::unique_ptr<PDBSymbolCompiland>
-  createCompilandSymbol(DbiModuleDescriptor MI);
+  template <typename ConcreteSymbolT, typename... Args>
+  SymIndexId createSymbol(Args &&... ConstructorArgs) {
+    SymIndexId Id = SymbolCache.size();
+    std::unique_ptr<ConcreteSymbolT> Symbol =
+        llvm::make_unique<ConcreteSymbolT>(
+            *this, Id, std::forward<Args>(ConstructorArgs)...);
+    std::unique_ptr<NativeRawSymbol> NRS = std::move(Symbol);
+    SymbolCache.push_back(std::move(NRS));
+    return Id;
+  }
 
   std::unique_ptr<PDBSymbolTypeEnum>
   createEnumSymbol(codeview::TypeIndex Index);
@@ -107,7 +115,11 @@ public:
   PDBFile &getPDBFile() { return *Pdb; }
   const PDBFile &getPDBFile() const { return *Pdb; }
 
+  NativeExeSymbol &getNativeGlobalScope();
+
 private:
+  SymIndexId ExeSymbol = 0;
+
   std::unique_ptr<PDBFile> Pdb;
   std::unique_ptr<BumpPtrAllocator> Allocator;
   std::vector<std::unique_ptr<NativeRawSymbol>> SymbolCache;

include/llvm/DebugInfo/PDB/PDBSymbol.h

@@ -49,9 +49,22 @@ class IPDBRawSymbol;
 class IPDBSession;
 
 #define DECLARE_PDB_SYMBOL_CONCRETE_TYPE(TagValue)                             \
+private:                                                                       \
+  using PDBSymbol::PDBSymbol;                                                  \
+  friend class PDBSymbol;                                                      \
+                                                                               \
+public:                                                                        \
   static const PDB_SymType Tag = TagValue;                                     \
   static bool classof(const PDBSymbol *S) { return S->getSymTag() == Tag; }
 
+#define DECLARE_PDB_SYMBOL_CUSTOM_TYPE(Condition)                              \
+private:                                                                       \
+  using PDBSymbol::PDBSymbol;                                                  \
+  friend class PDBSymbol;                                                      \
+                                                                               \
+public:                                                                        \
+  static bool classof(const PDBSymbol *S) { return Condition; }
+
 /// PDBSymbol defines the base of the inheritance hierarchy for concrete symbol
 /// types (e.g. functions, executables, vtables, etc).  All concrete symbol
 /// types inherit from PDBSymbol and expose the exact set of methods that are
@@ -59,14 +72,33 @@ class IPDBSession;
 /// reference "Lexical and Class Hierarchy of Symbol Types":
 /// https://msdn.microsoft.com/en-us/library/370hs6k4.aspx
 class PDBSymbol {
+  static std::unique_ptr<PDBSymbol> createSymbol(const IPDBSession &PDBSession,
+                                                 PDB_SymType Tag);
+
 protected:
-  PDBSymbol(const IPDBSession &PDBSession,
-            std::unique_ptr<IPDBRawSymbol> Symbol);
-  PDBSymbol(PDBSymbol &Symbol);
+  explicit PDBSymbol(const IPDBSession &PDBSession);
+  PDBSymbol(PDBSymbol &&Other);
 
 public:
   static std::unique_ptr<PDBSymbol>
-  create(const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol);
+  create(const IPDBSession &PDBSession,
+         std::unique_ptr<IPDBRawSymbol> RawSymbol);
+  static std::unique_ptr<PDBSymbol> create(const IPDBSession &PDBSession,
+                                           IPDBRawSymbol &RawSymbol);
+
+  template <typename ConcreteT>
+  static std::unique_ptr<ConcreteT>
+  createAs(const IPDBSession &PDBSession,
+           std::unique_ptr<IPDBRawSymbol> RawSymbol) {
+    std::unique_ptr<PDBSymbol> S = create(PDBSession, std::move(RawSymbol));
+    return unique_dyn_cast_or_null<ConcreteT>(std::move(S));
+  }
+  template <typename ConcreteT>
+  static std::unique_ptr<ConcreteT> createAs(const IPDBSession &PDBSession,
+                                             IPDBRawSymbol &RawSymbol) {
+    std::unique_ptr<PDBSymbol> S = create(PDBSession, RawSymbol);
+    return unique_dyn_cast_or_null<ConcreteT>(std::move(S));
+  }
 
   virtual ~PDBSymbol();
 
@@ -131,7 +163,8 @@ protected:
   }
 
   const IPDBSession &Session;
-  std::unique_ptr<IPDBRawSymbol> RawSymbol;
+  std::unique_ptr<IPDBRawSymbol> OwnedRawSymbol;
+  IPDBRawSymbol *RawSymbol = nullptr;
 };
 
 } // namespace llvm

include/llvm/DebugInfo/PDB/PDBSymbolAnnotation.h

@@ -18,12 +18,9 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolAnnotation : public PDBSymbol {
-public:
-  PDBSymbolAnnotation(const IPDBSession &PDBSession,
-                      std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Annotation)
 
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getAddressOffset)

include/llvm/DebugInfo/PDB/PDBSymbolBlock.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolBlock : public PDBSymbol {
-public:
-  PDBSymbolBlock(const IPDBSession &PDBSession,
-                 std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Block)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getAddressOffset)

include/llvm/DebugInfo/PDB/PDBSymbolCompiland.h

@@ -20,12 +20,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolCompiland : public PDBSymbol {
-public:
-  PDBSymbolCompiland(const IPDBSession &PDBSession,
-                     std::unique_ptr<IPDBRawSymbol> CompilandSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Compiland)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(isEditAndContinueEnabled)

include/llvm/DebugInfo/PDB/PDBSymbolCompilandDetails.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolCompilandDetails : public PDBSymbol {
-public:
-  PDBSymbolCompilandDetails(const IPDBSession &PDBSession,
-                            std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::CompilandDetails)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   void getFrontEndVersion(VersionInfo &Version) const {

include/llvm/DebugInfo/PDB/PDBSymbolCompilandEnv.h

@@ -18,12 +18,8 @@ namespace llvm {
 class raw_ostream;
 namespace pdb {
 class PDBSymbolCompilandEnv : public PDBSymbol {
-public:
-  PDBSymbolCompilandEnv(const IPDBSession &PDBSession,
-                        std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::CompilandEnv)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_ID_METHOD(getLexicalParent)

include/llvm/DebugInfo/PDB/PDBSymbolCustom.h

@@ -23,12 +23,8 @@ namespace pdb {
 /// fit anywhere else in the lexical hierarchy.
 /// https://msdn.microsoft.com/en-us/library/d88sf09h.aspx
 class PDBSymbolCustom : public PDBSymbol {
-public:
-  PDBSymbolCustom(const IPDBSession &PDBSession,
-                  std::unique_ptr<IPDBRawSymbol> CustomSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Custom)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   void getDataBytes(llvm::SmallVector<uint8_t, 32> &bytes);

include/llvm/DebugInfo/PDB/PDBSymbolData.h

@@ -21,12 +21,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolData : public PDBSymbol {
-public:
-  PDBSymbolData(const IPDBSession &PDBSession,
-                std::unique_ptr<IPDBRawSymbol> DataSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Data)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getAccess)

include/llvm/DebugInfo/PDB/PDBSymbolExe.h

@@ -20,12 +20,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolExe : public PDBSymbol {
-public:
-  PDBSymbolExe(const IPDBSession &PDBSession,
-               std::unique_ptr<IPDBRawSymbol> ExeSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Exe)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getAge)

include/llvm/DebugInfo/PDB/PDBSymbolFunc.h

@@ -22,18 +22,14 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolFunc : public PDBSymbol {
+  DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Function)
 public:
-  PDBSymbolFunc(const IPDBSession &PDBSession,
-                std::unique_ptr<IPDBRawSymbol> FuncSymbol);
-
   void dump(PDBSymDumper &Dumper) const override;
 
   bool isDestructor() const;
 
   std::unique_ptr<IPDBEnumChildren<PDBSymbolData>> getArguments() const;
 
-  DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Function)
-
   FORWARD_SYMBOL_METHOD(getAccess)
   FORWARD_SYMBOL_METHOD(getAddressOffset)
   FORWARD_SYMBOL_METHOD(getAddressSection)

include/llvm/DebugInfo/PDB/PDBSymbolFuncDebugEnd.h

@@ -20,12 +20,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolFuncDebugEnd : public PDBSymbol {
-public:
-  PDBSymbolFuncDebugEnd(const IPDBSession &PDBSession,
-                        std::unique_ptr<IPDBRawSymbol> FuncDebugEndSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::FuncDebugEnd)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getAddressOffset)

include/llvm/DebugInfo/PDB/PDBSymbolFuncDebugStart.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolFuncDebugStart : public PDBSymbol {
-public:
-  PDBSymbolFuncDebugStart(const IPDBSession &PDBSession,
-                          std::unique_ptr<IPDBRawSymbol> FuncDebugStartSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::FuncDebugStart)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getAddressOffset)

include/llvm/DebugInfo/PDB/PDBSymbolLabel.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolLabel : public PDBSymbol {
-public:
-  PDBSymbolLabel(const IPDBSession &PDBSession,
-                 std::unique_ptr<IPDBRawSymbol> LabelSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Label)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getAddressOffset)

include/llvm/DebugInfo/PDB/PDBSymbolPublicSymbol.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolPublicSymbol : public PDBSymbol {
-public:
-  PDBSymbolPublicSymbol(const IPDBSession &PDBSession,
-                        std::unique_ptr<IPDBRawSymbol> PublicSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::PublicSymbol)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getAddressOffset)

include/llvm/DebugInfo/PDB/PDBSymbolThunk.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolThunk : public PDBSymbol {
-public:
-  PDBSymbolThunk(const IPDBSession &PDBSession,
-                 std::unique_ptr<IPDBRawSymbol> ThunkSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Thunk)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getAccess)

include/llvm/DebugInfo/PDB/PDBSymbolTypeArray.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeArray : public PDBSymbol {
-public:
-  PDBSymbolTypeArray(const IPDBSession &PDBSession,
-                     std::unique_ptr<IPDBRawSymbol> ArrayTypeSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::ArrayType)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
   void dumpRight(PDBSymDumper &Dumper) const override;
 

include/llvm/DebugInfo/PDB/PDBSymbolTypeBaseClass.h

@@ -22,12 +22,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeBaseClass : public PDBSymbol {
-public:
-  PDBSymbolTypeBaseClass(const IPDBSession &PDBSession,
-                         std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::BaseClass)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getAccess)

include/llvm/DebugInfo/PDB/PDBSymbolTypeBuiltin.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeBuiltin : public PDBSymbol {
-public:
-  PDBSymbolTypeBuiltin(const IPDBSession &PDBSession,
-                       std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::BuiltinType)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getBuiltinType)

include/llvm/DebugInfo/PDB/PDBSymbolTypeCustom.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeCustom : public PDBSymbol {
-public:
-  PDBSymbolTypeCustom(const IPDBSession &PDBSession,
-                      std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::CustomType)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getOemId)

include/llvm/DebugInfo/PDB/PDBSymbolTypeDimension.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeDimension : public PDBSymbol {
-public:
-  PDBSymbolTypeDimension(const IPDBSession &PDBSession,
-                         std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Dimension)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getLowerBoundId)

include/llvm/DebugInfo/PDB/PDBSymbolTypeEnum.h

@@ -21,12 +21,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeEnum : public PDBSymbol {
-public:
-  PDBSymbolTypeEnum(const IPDBSession &PDBSession,
-                    std::unique_ptr<IPDBRawSymbol> EnumTypeSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Enum)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getBuiltinType)

include/llvm/DebugInfo/PDB/PDBSymbolTypeFriend.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeFriend : public PDBSymbol {
-public:
-  PDBSymbolTypeFriend(const IPDBSession &PDBSession,
-                      std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Friend)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_ID_METHOD(getClassParent)

include/llvm/DebugInfo/PDB/PDBSymbolTypeFunctionArg.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeFunctionArg : public PDBSymbol {
-public:
-  PDBSymbolTypeFunctionArg(const IPDBSession &PDBSession,
-                           std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::FunctionArg)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_ID_METHOD(getClassParent)

include/llvm/DebugInfo/PDB/PDBSymbolTypeFunctionSig.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeFunctionSig : public PDBSymbol {
-public:
-  PDBSymbolTypeFunctionSig(const IPDBSession &PDBSession,
-                           std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::FunctionSig)
-
+public:
   std::unique_ptr<IPDBEnumSymbols> getArguments() const;
 
   void dump(PDBSymDumper &Dumper) const override;

include/llvm/DebugInfo/PDB/PDBSymbolTypeManaged.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeManaged : public PDBSymbol {
-public:
-  PDBSymbolTypeManaged(const IPDBSession &PDBSession,
-                       std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::ManagedType)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getName)

include/llvm/DebugInfo/PDB/PDBSymbolTypePointer.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypePointer : public PDBSymbol {
-public:
-  PDBSymbolTypePointer(const IPDBSession &PDBSession,
-                       std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::PointerType)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
   void dumpRight(PDBSymDumper &Dumper) const override;
 

include/llvm/DebugInfo/PDB/PDBSymbolTypeTypedef.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeTypedef : public PDBSymbol {
-public:
-  PDBSymbolTypeTypedef(const IPDBSession &PDBSession,
-                       std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::Typedef)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(getBuiltinType)

include/llvm/DebugInfo/PDB/PDBSymbolTypeUDT.h

@@ -23,17 +23,13 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeUDT : public PDBSymbol {
+  DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::UDT)
 public:
-  PDBSymbolTypeUDT(const IPDBSession &PDBSession,
-                   std::unique_ptr<IPDBRawSymbol> UDTSymbol);
-
   std::unique_ptr<PDBSymbolTypeUDT> clone() const {
     return getSession().getConcreteSymbolById<PDBSymbolTypeUDT>(
         getSymIndexId());
   }
 
-  DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::UDT)
-
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_ID_METHOD(getClassParent)

include/llvm/DebugInfo/PDB/PDBSymbolTypeVTable.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeVTable : public PDBSymbol {
-public:
-  PDBSymbolTypeVTable(const IPDBSession &PDBSession,
-                      std::unique_ptr<IPDBRawSymbol> VtblSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::VTable)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_ID_METHOD(getClassParent)

include/llvm/DebugInfo/PDB/PDBSymbolTypeVTableShape.h

@@ -19,12 +19,8 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolTypeVTableShape : public PDBSymbol {
-public:
-  PDBSymbolTypeVTableShape(const IPDBSession &PDBSession,
-                           std::unique_ptr<IPDBRawSymbol> VtblShapeSymbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::VTableShape)
-
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_METHOD(isConstType)

include/llvm/DebugInfo/PDB/PDBSymbolUnknown.h

@@ -18,16 +18,11 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolUnknown : public PDBSymbol {
+  DECLARE_PDB_SYMBOL_CUSTOM_TYPE(S->getSymTag() == PDB_SymType::None ||
+                                 S->getSymTag() >= PDB_SymType::Max)
+
 public:
-  PDBSymbolUnknown(const IPDBSession &PDBSession,
-                   std::unique_ptr<IPDBRawSymbol> UnknownSymbol);
-
   void dump(PDBSymDumper &Dumper) const override;
-
-  static bool classof(const PDBSymbol *S) {
-    return (S->getSymTag() == PDB_SymType::None ||
-            S->getSymTag() >= PDB_SymType::Max);
-  }
 };
 
 } // namespace llvm

include/llvm/DebugInfo/PDB/PDBSymbolUsingNamespace.h

@@ -19,12 +19,9 @@ class raw_ostream;
 namespace pdb {
 
 class PDBSymbolUsingNamespace : public PDBSymbol {
-public:
-  PDBSymbolUsingNamespace(const IPDBSession &PDBSession,
-                          std::unique_ptr<IPDBRawSymbol> Symbol);
-
   DECLARE_PDB_SYMBOL_CONCRETE_TYPE(PDB_SymType::UsingNamespace)
 
+public:
   void dump(PDBSymDumper &Dumper) const override;
 
   FORWARD_SYMBOL_ID_METHOD(getLexicalParent)

lib/DebugInfo/PDB/DIA/DIARawSymbol.cpp

@@ -852,7 +852,7 @@ DIARawSymbol::getVirtualBaseTableType() const {
 
   auto RawVT = llvm::make_unique<DIARawSymbol>(Session, TableType);
   auto Pointer =
-      llvm::make_unique<PDBSymbolTypePointer>(Session, std::move(RawVT));
+      PDBSymbol::createAs<PDBSymbolTypePointer>(Session, std::move(RawVT));
   return unique_dyn_cast<PDBSymbolTypeBuiltin>(Pointer->getPointeeType());
 }
 

lib/DebugInfo/PDB/DIA/DIASectionContrib.cpp

@@ -25,7 +25,7 @@ std::unique_ptr<PDBSymbolCompiland> DIASectionContrib::getCompiland() const {
     return nullptr;
 
   auto RawSymbol = llvm::make_unique<DIARawSymbol>(Session, Symbol);
-  return llvm::make_unique<PDBSymbolCompiland>(Session, std::move(RawSymbol));
+  return PDBSymbol::createAs<PDBSymbolCompiland>(Session, std::move(RawSymbol));
 }
 
 template <typename ArgType>

lib/DebugInfo/PDB/Native/NativeBuiltinSymbol.cpp

@@ -16,8 +16,8 @@ namespace pdb {
 NativeBuiltinSymbol::NativeBuiltinSymbol(NativeSession &PDBSession,
                                          SymIndexId Id, PDB_BuiltinType T,
                                          uint64_t L)
-    : NativeRawSymbol(PDBSession, Id), Session(PDBSession), Type(T), Length(L) {
-}
+    : NativeRawSymbol(PDBSession, PDB_SymType::BuiltinType, Id),
+      Session(PDBSession), Type(T), Length(L) {}
 
 NativeBuiltinSymbol::~NativeBuiltinSymbol() {}
 

lib/DebugInfo/PDB/Native/NativeCompilandSymbol.cpp

@@ -17,7 +17,7 @@ namespace pdb {
 NativeCompilandSymbol::NativeCompilandSymbol(NativeSession &Session,
                                              SymIndexId SymbolId,
                                              DbiModuleDescriptor MI)
-    : NativeRawSymbol(Session, SymbolId), Module(MI) {}
+    : NativeRawSymbol(Session, PDB_SymType::Compiland, SymbolId), Module(MI) {}
 
 PDB_SymType NativeCompilandSymbol::getSymTag() const {
   return PDB_SymType::Compiland;

lib/DebugInfo/PDB/Native/NativeEnumModules.cpp

@@ -10,33 +10,30 @@
 #include "llvm/DebugInfo/PDB/Native/NativeEnumModules.h"
 
 #include "llvm/DebugInfo/PDB/IPDBEnumChildren.h"
-#include "llvm/DebugInfo/PDB/Native/DbiModuleList.h"
 #include "llvm/DebugInfo/PDB/Native/NativeCompilandSymbol.h"
+#include "llvm/DebugInfo/PDB/Native/NativeExeSymbol.h"
 #include "llvm/DebugInfo/PDB/Native/NativeSession.h"
 #include "llvm/DebugInfo/PDB/PDBSymbol.h"
 #include "llvm/DebugInfo/PDB/PDBSymbolCompiland.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolExe.h"
 
 namespace llvm {
 namespace pdb {
 
-NativeEnumModules::NativeEnumModules(NativeSession &PDBSession,
-                                     const DbiModuleList &Modules,
-                                     uint32_t Index)
-    : Session(PDBSession), Modules(Modules), Index(Index) {}
+NativeEnumModules::NativeEnumModules(NativeSession &PDBSession, uint32_t Index)
+    : Session(PDBSession), Index(Index) {}
 
 uint32_t NativeEnumModules::getChildCount() const {
-  return static_cast<uint32_t>(Modules.getModuleCount());
+  return Session.getNativeGlobalScope().getNumCompilands();
 }
 
 std::unique_ptr<PDBSymbol>
-NativeEnumModules::getChildAtIndex(uint32_t Index) const {
-  if (Index >= Modules.getModuleCount())
-    return nullptr;
-  return Session.createCompilandSymbol(Modules.getModuleDescriptor(Index));
+NativeEnumModules::getChildAtIndex(uint32_t N) const {
+  return Session.getNativeGlobalScope().getOrCreateCompiland(N);
 }
 
 std::unique_ptr<PDBSymbol> NativeEnumModules::getNext() {
-  if (Index >= Modules.getModuleCount())
+  if (Index >= getChildCount())
     return nullptr;
   return getChildAtIndex(Index++);
 }
@@ -44,7 +41,7 @@ std::unique_ptr<PDBSymbol> NativeEnumModules::getNext() {
 void NativeEnumModules::reset() { Index = 0; }
 
 NativeEnumModules *NativeEnumModules::clone() const {
-  return new NativeEnumModules(Session, Modules, Index);
+  return new NativeEnumModules(Session, Index);
 }
 
 }

lib/DebugInfo/PDB/Native/NativeEnumSymbol.cpp

@@ -21,7 +21,7 @@ using namespace llvm::pdb;
 
 NativeEnumSymbol::NativeEnumSymbol(NativeSession &Session, SymIndexId Id,
                                    const codeview::CVType &CVT)
-    : NativeRawSymbol(Session, Id), CV(CVT),
+    : NativeRawSymbol(Session, PDB_SymType::Enum, Id), CV(CVT),
       Record(codeview::TypeRecordKind::Enum) {
   assert(CV.kind() == codeview::TypeLeafKind::LF_ENUM);
   cantFail(visitTypeRecord(CV, *this));

lib/DebugInfo/PDB/Native/NativeExeSymbol.cpp

@@ -12,14 +12,25 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/DebugInfo/PDB/Native/DbiStream.h"
 #include "llvm/DebugInfo/PDB/Native/InfoStream.h"
+#include "llvm/DebugInfo/PDB/Native/NativeCompilandSymbol.h"
 #include "llvm/DebugInfo/PDB/Native/NativeEnumModules.h"
 #include "llvm/DebugInfo/PDB/Native/PDBFile.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolCompiland.h"
 
-namespace llvm {
-namespace pdb {
+using namespace llvm;
+using namespace llvm::pdb;
 
 NativeExeSymbol::NativeExeSymbol(NativeSession &Session, SymIndexId SymbolId)
-    : NativeRawSymbol(Session, SymbolId), File(Session.getPDBFile()) {}
+    : NativeRawSymbol(Session, PDB_SymType::Exe, SymbolId),
+      File(Session.getPDBFile()) {
+  Expected<DbiStream &> DbiS = File.getPDBDbiStream();
+  if (!DbiS) {
+    consumeError(DbiS.takeError());
+    return;
+  }
+  Dbi = &DbiS.get();
+  Compilands.resize(Dbi->modules().getModuleCount());
+}
 
 std::unique_ptr<NativeRawSymbol> NativeExeSymbol::clone() const {
   return llvm::make_unique<NativeExeSymbol>(Session, SymbolId);
@@ -29,13 +40,7 @@ std::unique_ptr<IPDBEnumSymbols>
 NativeExeSymbol::findChildren(PDB_SymType Type) const {
   switch (Type) {
   case PDB_SymType::Compiland: {
-    auto Dbi = File.getPDBDbiStream();
-    if (Dbi) {
-      const DbiModuleList &Modules = Dbi->modules();
-      return std::unique_ptr<IPDBEnumSymbols>(
-          new NativeEnumModules(Session, Modules));
-    }
-    consumeError(Dbi.takeError());
+    return std::unique_ptr<IPDBEnumSymbols>(new NativeEnumModules(Session));
     break;
   }
   case PDB_SymType::Enum:
@@ -82,5 +87,26 @@ bool NativeExeSymbol::hasPrivateSymbols() const {
   return false;
 }
 
-} // namespace pdb
-} // namespace llvm
+uint32_t NativeExeSymbol::getNumCompilands() const {
+  if (!Dbi)
+    return 0;
+
+  return Dbi->modules().getModuleCount();
+}
+
+std::unique_ptr<PDBSymbolCompiland>
+NativeExeSymbol::getOrCreateCompiland(uint32_t Index) {
+  if (!Dbi)
+    return nullptr;
+
+  if (Index >= Compilands.size())
+    return nullptr;
+
+  if (Compilands[Index] == 0) {
+    const DbiModuleList &Modules = Dbi->modules();
+    Compilands[Index] = Session.createSymbol<NativeCompilandSymbol>(
+        Modules.getModuleDescriptor(Index));
+  }
+
+  return Session.getConcreteSymbolById<PDBSymbolCompiland>(Compilands[Index]);
+}

lib/DebugInfo/PDB/Native/NativeRawSymbol.cpp

@@ -14,8 +14,9 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-NativeRawSymbol::NativeRawSymbol(NativeSession &PDBSession, SymIndexId SymbolId)
-    : Session(PDBSession), SymbolId(SymbolId) {}
+NativeRawSymbol::NativeRawSymbol(NativeSession &PDBSession, PDB_SymType Tag,
+                                 SymIndexId SymbolId)
+    : Session(PDBSession), Tag(Tag), SymbolId(SymbolId) {}
 
 void NativeRawSymbol::dump(raw_ostream &OS, int Indent) const {}
 
@@ -374,9 +375,7 @@ PDB_DataKind NativeRawSymbol::getDataKind() const {
   return PDB_DataKind::Unknown;
 }
 
-PDB_SymType NativeRawSymbol::getSymTag() const {
-  return PDB_SymType::None;
-}
+PDB_SymType NativeRawSymbol::getSymTag() const { return Tag; }
 
 codeview::GUID NativeRawSymbol::getGuid() const { return codeview::GUID{{0}}; }
 

lib/DebugInfo/PDB/Native/NativeSession.cpp

@@ -63,7 +63,10 @@ static const struct BuiltinTypeEntry {
 
 NativeSession::NativeSession(std::unique_ptr<PDBFile> PdbFile,
                              std::unique_ptr<BumpPtrAllocator> Allocator)
-    : Pdb(std::move(PdbFile)), Allocator(std::move(Allocator)) {}
+    : Pdb(std::move(PdbFile)), Allocator(std::move(Allocator)) {
+  // Id 0 is reserved for the invalid symbol.
+  SymbolCache.push_back(nullptr);
+}
 
 NativeSession::~NativeSession() = default;
 
@@ -91,20 +94,10 @@ Error NativeSession::createFromExe(StringRef Path,
   return make_error<RawError>(raw_error_code::feature_unsupported);
 }
 
-std::unique_ptr<PDBSymbolCompiland>
-NativeSession::createCompilandSymbol(DbiModuleDescriptor MI) {
-  const auto Id = static_cast<SymIndexId>(SymbolCache.size());
-  SymbolCache.push_back(
-      llvm::make_unique<NativeCompilandSymbol>(*this, Id, MI));
-  return llvm::make_unique<PDBSymbolCompiland>(
-      *this, std::unique_ptr<IPDBRawSymbol>(SymbolCache[Id]->clone()));
-}
-
 std::unique_ptr<PDBSymbolTypeEnum>
 NativeSession::createEnumSymbol(codeview::TypeIndex Index) {
   const auto Id = findSymbolByTypeIndex(Index);
-  return llvm::make_unique<PDBSymbolTypeEnum>(
-      *this, std::unique_ptr<IPDBRawSymbol>(SymbolCache[Id]->clone()));
+  return PDBSymbol::createAs<PDBSymbolTypeEnum>(*this, *SymbolCache[Id]);
 }
 
 std::unique_ptr<IPDBEnumSymbols>
@@ -167,20 +160,14 @@ uint64_t NativeSession::getLoadAddress() const { return 0; }
 bool NativeSession::setLoadAddress(uint64_t Address) { return false; }
 
 std::unique_ptr<PDBSymbolExe> NativeSession::getGlobalScope() {
-  const auto Id = static_cast<SymIndexId>(SymbolCache.size());
-  SymbolCache.push_back(llvm::make_unique<NativeExeSymbol>(*this, Id));
-  auto RawSymbol = SymbolCache[Id]->clone();
-  auto PdbSymbol(PDBSymbol::create(*this, std::move(RawSymbol)));
-  std::unique_ptr<PDBSymbolExe> ExeSymbol(
-      static_cast<PDBSymbolExe *>(PdbSymbol.release()));
-  return ExeSymbol;
+  return PDBSymbol::createAs<PDBSymbolExe>(*this, getNativeGlobalScope());
 }
 
 std::unique_ptr<PDBSymbol>
 NativeSession::getSymbolById(uint32_t SymbolId) const {
   // If the caller has a SymbolId, it'd better be in our SymbolCache.
   return SymbolId < SymbolCache.size()
-             ? PDBSymbol::create(*this, SymbolCache[SymbolId]->clone())
+             ? PDBSymbol::create(*this, *SymbolCache[SymbolId])
              : nullptr;
 }
 
@@ -290,3 +277,11 @@ std::unique_ptr<IPDBEnumSectionContribs>
 NativeSession::getSectionContribs() const {
   return nullptr;
 }
+
+NativeExeSymbol &NativeSession::getNativeGlobalScope() {
+  if (ExeSymbol == 0) {
+    ExeSymbol = static_cast<SymIndexId>(SymbolCache.size());
+    SymbolCache.push_back(llvm::make_unique<NativeExeSymbol>(*this, ExeSymbol));
+  }
+  return static_cast<NativeExeSymbol &>(*SymbolCache[ExeSymbol]);
+}

lib/DebugInfo/PDB/PDBSymbol.cpp

@@ -50,23 +50,20 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbol::PDBSymbol(const IPDBSession &PDBSession,
-                     std::unique_ptr<IPDBRawSymbol> Symbol)
-    : Session(PDBSession), RawSymbol(std::move(Symbol)) {}
+PDBSymbol::PDBSymbol(const IPDBSession &PDBSession) : Session(PDBSession) {}
 
-PDBSymbol::PDBSymbol(PDBSymbol &Symbol)
-    : Session(Symbol.Session), RawSymbol(std::move(Symbol.RawSymbol)) {}
+PDBSymbol::PDBSymbol(PDBSymbol &&Other)
+    : Session(Other.Session), RawSymbol(std::move(Other.RawSymbol)) {}
 
 PDBSymbol::~PDBSymbol() = default;
 
 #define FACTORY_SYMTAG_CASE(Tag, Type)                                         \
   case PDB_SymType::Tag:                                                       \
-    return std::unique_ptr<PDBSymbol>(new Type(PDBSession, std::move(Symbol)));
+    return std::unique_ptr<PDBSymbol>(new Type(PDBSession));
 
 std::unique_ptr<PDBSymbol>
-PDBSymbol::create(const IPDBSession &PDBSession,
-                  std::unique_ptr<IPDBRawSymbol> Symbol) {
-  switch (Symbol->getSymTag()) {
+PDBSymbol::createSymbol(const IPDBSession &PDBSession, PDB_SymType Tag) {
+  switch (Tag) {
     FACTORY_SYMTAG_CASE(Exe, PDBSymbolExe)
     FACTORY_SYMTAG_CASE(Compiland, PDBSymbolCompiland)
     FACTORY_SYMTAG_CASE(CompilandDetails, PDBSymbolCompilandDetails)
@@ -98,11 +95,26 @@ PDBSymbol::create(const IPDBSession &PDBSession,
     FACTORY_SYMTAG_CASE(ManagedType, PDBSymbolTypeManaged)
     FACTORY_SYMTAG_CASE(Dimension, PDBSymbolTypeDimension)
   default:
-    return std::unique_ptr<PDBSymbol>(
-        new PDBSymbolUnknown(PDBSession, std::move(Symbol)));
+    return std::unique_ptr<PDBSymbol>(new PDBSymbolUnknown(PDBSession));
   }
 }
 
+std::unique_ptr<PDBSymbol>
+PDBSymbol::create(const IPDBSession &PDBSession,
+                  std::unique_ptr<IPDBRawSymbol> RawSymbol) {
+  auto SymbolPtr = createSymbol(PDBSession, RawSymbol->getSymTag());
+  SymbolPtr->RawSymbol = RawSymbol.get();
+  SymbolPtr->OwnedRawSymbol = std::move(RawSymbol);
+  return std::move(SymbolPtr);
+}
+
+std::unique_ptr<PDBSymbol> PDBSymbol::create(const IPDBSession &PDBSession,
+                                             IPDBRawSymbol &RawSymbol) {
+  auto SymbolPtr = createSymbol(PDBSession, RawSymbol.getSymTag());
+  SymbolPtr->RawSymbol = &RawSymbol;
+  return std::move(SymbolPtr);
+}
+
 void PDBSymbol::defaultDump(raw_ostream &OS, int Indent) const {
   RawSymbol->dump(OS, Indent);
 }

lib/DebugInfo/PDB/PDBSymbolAnnotation.cpp

@@ -16,12 +16,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolAnnotation::PDBSymbolAnnotation(const IPDBSession &PDBSession,
-                                         std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Annotation);
-}
-
 void PDBSymbolAnnotation::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolBlock.cpp

@@ -17,10 +17,4 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolBlock::PDBSymbolBlock(const IPDBSession &PDBSession,
-                               std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Block);
-}
-
 void PDBSymbolBlock::dump(PDBSymDumper &Dumper) const { Dumper.dump(*this); }

lib/DebugInfo/PDB/PDBSymbolCompiland.cpp

@@ -22,12 +22,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolCompiland::PDBSymbolCompiland(const IPDBSession &PDBSession,
-                                       std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Compiland);
-}
-
 void PDBSymbolCompiland::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolCompilandDetails.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolCompilandDetails::PDBSymbolCompilandDetails(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::CompilandDetails);
-}
-
 void PDBSymbolCompilandDetails::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolCompilandEnv.cpp

@@ -18,12 +18,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolCompilandEnv::PDBSymbolCompilandEnv(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::CompilandEnv);
-}
-
 std::string PDBSymbolCompilandEnv::getValue() const {
   Variant Value = RawSymbol->getValue();
   if (Value.Type != PDB_VariantType::String)

lib/DebugInfo/PDB/PDBSymbolCustom.cpp

@@ -18,12 +18,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolCustom::PDBSymbolCustom(const IPDBSession &PDBSession,
-                                 std::unique_ptr<IPDBRawSymbol> CustomSymbol)
-    : PDBSymbol(PDBSession, std::move(CustomSymbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Custom);
-}
-
 void PDBSymbolCustom::getDataBytes(llvm::SmallVector<uint8_t, 32> &bytes) {
   RawSymbol->getDataBytes(bytes);
 }

lib/DebugInfo/PDB/PDBSymbolData.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolData::PDBSymbolData(const IPDBSession &PDBSession,
-                             std::unique_ptr<IPDBRawSymbol> DataSymbol)
-    : PDBSymbol(PDBSession, std::move(DataSymbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Data);
-}
-
 void PDBSymbolData::dump(PDBSymDumper &Dumper) const { Dumper.dump(*this); }
 
 std::unique_ptr<IPDBEnumLineNumbers> PDBSymbolData::getLineNumbers() const {

lib/DebugInfo/PDB/PDBSymbolExe.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolExe::PDBSymbolExe(const IPDBSession &PDBSession,
-                           std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Exe);
-}
-
 void PDBSymbolExe::dump(PDBSymDumper &Dumper) const { Dumper.dump(*this); }
 
 uint32_t PDBSymbolExe::getPointerByteSize() const {

lib/DebugInfo/PDB/PDBSymbolFunc.cpp

@@ -82,12 +82,6 @@ private:
 };
 }
 
-PDBSymbolFunc::PDBSymbolFunc(const IPDBSession &PDBSession,
-                             std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Function);
-}
-
 std::unique_ptr<IPDBEnumChildren<PDBSymbolData>>
 PDBSymbolFunc::getArguments() const {
   return llvm::make_unique<FunctionArgEnumerator>(Session, *this);

lib/DebugInfo/PDB/PDBSymbolFuncDebugEnd.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolFuncDebugEnd::PDBSymbolFuncDebugEnd(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::FuncDebugEnd);
-}
-
 void PDBSymbolFuncDebugEnd::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolFuncDebugStart.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolFuncDebugStart::PDBSymbolFuncDebugStart(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::FuncDebugStart);
-}
-
 void PDBSymbolFuncDebugStart::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolLabel.cpp

@@ -16,10 +16,4 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolLabel::PDBSymbolLabel(const IPDBSession &PDBSession,
-                               std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Label);
-}
-
 void PDBSymbolLabel::dump(PDBSymDumper &Dumper) const { Dumper.dump(*this); }

lib/DebugInfo/PDB/PDBSymbolPublicSymbol.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolPublicSymbol::PDBSymbolPublicSymbol(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::PublicSymbol);
-}
-
 void PDBSymbolPublicSymbol::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolThunk.cpp

@@ -16,10 +16,4 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolThunk::PDBSymbolThunk(const IPDBSession &PDBSession,
-                               std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Thunk);
-}
-
 void PDBSymbolThunk::dump(PDBSymDumper &Dumper) const { Dumper.dump(*this); }

lib/DebugInfo/PDB/PDBSymbolTypeArray.cpp

@@ -16,12 +16,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeArray::PDBSymbolTypeArray(const IPDBSession &PDBSession,
-                                       std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::ArrayType);
-}
-
 void PDBSymbolTypeArray::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypeBaseClass.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeBaseClass::PDBSymbolTypeBaseClass(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::BaseClass);
-}
-
 void PDBSymbolTypeBaseClass::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypeBuiltin.cpp

@@ -16,12 +16,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeBuiltin::PDBSymbolTypeBuiltin(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::BuiltinType);
-}
-
 void PDBSymbolTypeBuiltin::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypeCustom.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeCustom::PDBSymbolTypeCustom(const IPDBSession &PDBSession,
-                                         std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::CustomType);
-}
-
 void PDBSymbolTypeCustom::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypeDimension.cpp

@@ -17,13 +17,6 @@
 
 using namespace llvm;
 using namespace llvm::pdb;
-
-PDBSymbolTypeDimension::PDBSymbolTypeDimension(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Dimension);
-}
-
 void PDBSymbolTypeDimension::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypeEnum.cpp

@@ -17,10 +17,4 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeEnum::PDBSymbolTypeEnum(const IPDBSession &PDBSession,
-                                     std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Enum);
-}
-
 void PDBSymbolTypeEnum::dump(PDBSymDumper &Dumper) const { Dumper.dump(*this); }

lib/DebugInfo/PDB/PDBSymbolTypeFriend.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeFriend::PDBSymbolTypeFriend(const IPDBSession &PDBSession,
-                                         std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Friend);
-}
-
 void PDBSymbolTypeFriend::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypeFunctionArg.cpp

@@ -16,12 +16,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeFunctionArg::PDBSymbolTypeFunctionArg(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::FunctionArg);
-}
-
 void PDBSymbolTypeFunctionArg::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypeFunctionSig.cpp

@@ -67,12 +67,6 @@ private:
 };
 }
 
-PDBSymbolTypeFunctionSig::PDBSymbolTypeFunctionSig(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::FunctionSig);
-}
-
 std::unique_ptr<IPDBEnumSymbols>
 PDBSymbolTypeFunctionSig::getArguments() const {
   return llvm::make_unique<FunctionArgEnumerator>(Session, *this);

lib/DebugInfo/PDB/PDBSymbolTypeManaged.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeManaged::PDBSymbolTypeManaged(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::ManagedType);
-}
-
 void PDBSymbolTypeManaged::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypePointer.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypePointer::PDBSymbolTypePointer(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::PointerType);
-}
-
 void PDBSymbolTypePointer::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypeTypedef.cpp

@@ -16,12 +16,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeTypedef::PDBSymbolTypeTypedef(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::Typedef);
-}
-
 void PDBSymbolTypeTypedef::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypeUDT.cpp

@@ -23,10 +23,4 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeUDT::PDBSymbolTypeUDT(const IPDBSession &PDBSession,
-                                   std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::UDT);
-}
-
 void PDBSymbolTypeUDT::dump(PDBSymDumper &Dumper) const { Dumper.dump(*this); }

lib/DebugInfo/PDB/PDBSymbolTypeVTable.cpp

@@ -16,12 +16,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeVTable::PDBSymbolTypeVTable(const IPDBSession &PDBSession,
-                                         std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::VTable);
-}
-
 void PDBSymbolTypeVTable::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolTypeVTableShape.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolTypeVTableShape::PDBSymbolTypeVTableShape(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::VTableShape);
-}
-
 void PDBSymbolTypeVTableShape::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

lib/DebugInfo/PDB/PDBSymbolUnknown.cpp

@@ -17,8 +17,4 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolUnknown::PDBSymbolUnknown(const IPDBSession &PDBSession,
-                                   std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {}
-
 void PDBSymbolUnknown::dump(PDBSymDumper &Dumper) const { Dumper.dump(*this); }

lib/DebugInfo/PDB/PDBSymbolUsingNamespace.cpp

@@ -17,12 +17,6 @@
 using namespace llvm;
 using namespace llvm::pdb;
 
-PDBSymbolUsingNamespace::PDBSymbolUsingNamespace(
-    const IPDBSession &PDBSession, std::unique_ptr<IPDBRawSymbol> Symbol)
-    : PDBSymbol(PDBSession, std::move(Symbol)) {
-  assert(RawSymbol->getSymTag() == PDB_SymType::UsingNamespace);
-}
-
 void PDBSymbolUsingNamespace::dump(PDBSymDumper &Dumper) const {
   Dumper.dump(*this);
 }

tools/llvm-pdbutil/llvm-pdbutil.cpp

@@ -1054,7 +1054,9 @@ static void dumpPretty(StringRef Path) {
     Printer.NewLine();
     WithColor(Printer, PDB_ColorItem::SectionHeader).get()
         << "---COMPILANDS---";
-    if (auto Compilands = GlobalScope->findAllChildren<PDBSymbolCompiland>()) {
+    auto Compilands = GlobalScope->findAllChildren<PDBSymbolCompiland>();
+
+    if (Compilands) {
       Printer.Indent();
       CompilandDumper Dumper(Printer);
       CompilandDumpFlags options = CompilandDumper::Flags::None;

unittests/DebugInfo/PDB/CMakeLists.txt

@@ -6,6 +6,7 @@ set(LLVM_LINK_COMPONENTS
 
 add_llvm_unittest(DebugInfoPDBTests
   HashTableTest.cpp
+  NativeSymbolReuseTest.cpp
   StringTableBuilderTest.cpp
   PDBApiTest.cpp
   )

unittests/DebugInfo/PDB/NativeSymbolReuseTest.cpp

@@ -0,0 +1,128 @@
+//===- NativeSymbolReuseTest.cpp ------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/PDB/PDB.h"
+
+#include "llvm/DebugInfo/PDB/IPDBSession.h"
+#include "llvm/DebugInfo/PDB/Native/NativeSession.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolCompiland.h"
+#include "llvm/DebugInfo/PDB/PDBSymbolExe.h"
+#include "llvm/Support/Path.h"
+
+#include "llvm/Testing/Support/Error.h"
+#include "llvm/Testing/Support/SupportHelpers.h"
+
+#include "gtest/gtest.h"
+
+using namespace llvm;
+using namespace llvm::pdb;
+
+TEST(NativeSymbolReuseTest, GlobalSymbolReuse) {
+  SmallString<128> InputsDir = unittest::getInputFileDirectory();
+  llvm::sys::path::append(InputsDir, "empty.pdb");
+
+  std::unique_ptr<IPDBSession> S;
+  Error E = pdb::loadDataForPDB(PDB_ReaderType::Native, InputsDir, S);
+
+  ASSERT_THAT_ERROR(std::move(E), Succeeded());
+
+  SymIndexId GlobalId;
+  {
+    auto GS1 = S->getGlobalScope();
+    auto GS2 = S->getGlobalScope();
+
+    GlobalId = GS1->getSymIndexId();
+    SymIndexId Id2 = GS1->getSymIndexId();
+    EXPECT_EQ(GlobalId, Id2);
+  }
+
+  {
+    auto GS3 = S->getGlobalScope();
+
+    SymIndexId Id3 = GS3->getSymIndexId();
+    EXPECT_EQ(GlobalId, Id3);
+  }
+}
+
+TEST(NativeSymbolReuseTest, CompilandSymbolReuse) {
+  SmallString<128> InputsDir = unittest::getInputFileDirectory();
+  llvm::sys::path::append(InputsDir, "empty.pdb");
+
+  std::unique_ptr<IPDBSession> S;
+  Error E = pdb::loadDataForPDB(PDB_ReaderType::Native, InputsDir, S);
+
+  ASSERT_THAT_ERROR(std::move(E), Succeeded());
+
+  auto GS = S->getGlobalScope();
+
+  std::vector<SymIndexId> CompilandIds;
+  {
+    auto Compilands = GS->findAllChildren<PDBSymbolCompiland>();
+    ASSERT_NE(nullptr, Compilands);
+    ASSERT_EQ(2, Compilands->getChildCount());
+    std::vector<SymIndexId> Ids2;
+
+    // First try resetting the enumerator, then try destroying the enumerator
+    // and constructing another one.
+    while (auto Compiland = Compilands->getNext())
+      CompilandIds.push_back(Compiland->getSymIndexId());
+    Compilands->reset();
+    while (auto Compiland = Compilands->getNext())
+      Ids2.push_back(Compiland->getSymIndexId());
+
+    EXPECT_EQ(CompilandIds, Ids2);
+  }
+
+  {
+    auto Compilands = GS->findAllChildren<PDBSymbolCompiland>();
+    ASSERT_NE(nullptr, Compilands);
+    ASSERT_EQ(2U, Compilands->getChildCount());
+
+    std::vector<SymIndexId> Ids3;
+    while (auto Compiland = Compilands->getNext())
+      Ids3.push_back(Compiland->getSymIndexId());
+
+    EXPECT_EQ(CompilandIds, Ids3);
+  }
+}
+
+TEST(NativeSymbolReuseTest, CompilandSymbolReuseBackwards) {
+  SmallString<128> InputsDir = unittest::getInputFileDirectory();
+  llvm::sys::path::append(InputsDir, "empty.pdb");
+
+  std::unique_ptr<IPDBSession> S;
+  Error E = pdb::loadDataForPDB(PDB_ReaderType::Native, InputsDir, S);
+
+  ASSERT_THAT_ERROR(std::move(E), Succeeded());
+
+  auto GS = S->getGlobalScope();
+
+  // This time do the first iteration backwards, and make sure that when you
+  // then iterate them forwards, the IDs come out in reverse.
+  std::vector<SymIndexId> CompilandIds;
+  {
+    auto Compilands = GS->findAllChildren<PDBSymbolCompiland>();
+    ASSERT_NE(nullptr, Compilands);
+    ASSERT_EQ(2U, Compilands->getChildCount());
+
+    std::vector<SymIndexId> Ids2;
+
+    for (int I = Compilands->getChildCount() - 1; I >= 0; --I) {
+      auto Compiland = Compilands->getChildAtIndex(I);
+      CompilandIds.push_back(Compiland->getSymIndexId());
+    }
+
+    while (auto Compiland = Compilands->getNext())
+      Ids2.push_back(Compiland->getSymIndexId());
+
+    auto ReversedIter = llvm::reverse(Ids2);
+    std::vector<SymIndexId> Reversed{ReversedIter.begin(), ReversedIter.end()};
+    EXPECT_EQ(CompilandIds, Reversed);
+  }
+}