SymbolVendor: Move compile unit handling into the SymbolFile class

[labath]

Summary

SymbolFile classes are responsible for creating CompileUnit instances
and they already need to have a notion of the id<->CompileUnit mapping
(because of APIs like ParseCompileUnitAtIndex). However, the
SymbolVendor has remained as the thing responsible for caching created
units (which the SymbolFiles were calling via convoluted constructs like
"m_obj_file->GetModule()->GetSymbolVendor()->SetCompileUnitAtIndex(...)").

This patch moves the responsibility of caching the units into the
SymbolFile class. It does this by moving the implementation of
SymbolVendor::{GetNumCompileUnits,GetCompileUnitAtIndex} into the
equivalent SymbolFile functions. The SymbolVendor functions become just
a passthrough much like the rest of SymbolVendor.

The original implementations of SymbolFile::GetNumCompileUnits is moved
to "CalculateNumCompileUnits", and are made protected, as the "Get"
function is the external api of the class.
SymbolFile::ParseCompileUnitAtIndex is made protected for the same
reason.

This is the first step in removing the SymbolVendor indirection, as
proposed in
http://lists.llvm.org/pipermail/lldb-dev/2019-June/015071.html. After
removing all interesting logic from the SymbolVendor class, I'll proceed
with removing the indirection itself.

[clayborg]

Looks good. Just one question about caching the calculated number of compile units.

source/Symbol/SymbolFile.cpp

174–182

For symbol files without compile units we will end up calling into CalculateNumCompileUnits() many tines. Can we set a bool to indicate we have already calculated the number of compile units to avoid this?

[labath]

• Make the compile unit list an Optional<vector> to have an explicit way of saying "we've already tried to compute the number of units and it was zero"

include/lldb/Symbol/SymbolFile.h

public:
   /// in "uint32_t SymbolFile::GetAbilities()) will have this function
   /// called if it is chosen to parse an object file. More complete
   /// initialization can happen in this function which will get called
   /// prior to any other functions in the SymbolFile protocol.
   virtual void InitializeObject() {}
 
   // Compile Unit function calls
   // Approach 1 - iterator
-  virtual uint32_t GetNumCompileUnits() = 0;
-  virtual lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) = 0;
+  uint32_t GetNumCompileUnits();
+  lldb::CompUnitSP GetCompileUnitAtIndex(uint32_t idx);
 
   virtual lldb::LanguageType ParseLanguage(CompileUnit &comp_unit) = 0;
   virtual size_t ParseFunctions(CompileUnit &comp_unit) = 0;
   virtual bool ParseLineTable(CompileUnit &comp_unit) = 0;
   virtual bool ParseDebugMacros(CompileUnit &comp_unit) = 0;
   virtual bool ParseSupportFiles(CompileUnit &comp_unit,
                                  FileSpecList &support_files) = 0;
   virtual size_t ParseTypes(CompileUnit &comp_unit) = 0;
struct RegisterInfoResolver {
     virtual const RegisterInfo *ResolveNumber(lldb::RegisterKind kind,
                                               uint32_t number) const = 0;
   };
   virtual lldb::UnwindPlanSP
   GetUnwindPlan(const Address &address, const RegisterInfoResolver &resolver) {
     return nullptr;
   }
 
-  virtual void Dump(Stream &s) {}
+  virtual void Dump(Stream &s);
 
 protected:
   void AssertModuleLock();
+  virtual uint32_t CalculateNumCompileUnits() = 0;
+  virtual lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t idx) = 0;
+
+  void SetCompileUnitAtIndex(uint32_t idx, const lldb::CompUnitSP &cu_sp);
 
   ObjectFile *m_obj_file; // The object file that symbols can be extracted from.
+  llvm::Optional<std::vector<lldb::CompUnitSP>> m_compile_units;
   uint32_t m_abilities;
   bool m_calculated_abilities;
 
 private:
   DISALLOW_COPY_AND_ASSIGN(SymbolFile);
 };
 
 } // namespace lldb_private
 
 #endif // liblldb_SymbolFile_h_

include/lldb/Symbol/SymbolVendor.h

virtual size_t FindTypes(const std::vector<CompilerContext> &context,
                            bool append, TypeMap &types);
 
   virtual CompilerDeclContext
   FindNamespace(ConstString name,
                 const CompilerDeclContext *parent_decl_ctx);
 
   virtual size_t GetNumCompileUnits();
 
-  virtual bool SetCompileUnitAtIndex(size_t cu_idx,
-                                     const lldb::CompUnitSP &cu_sp);
-
   virtual lldb::CompUnitSP GetCompileUnitAtIndex(size_t idx);
 
   TypeList &GetTypeList() { return m_type_list; }
 
   const TypeList &GetTypeList() const { return m_type_list; }
 
   virtual size_t GetTypes(SymbolContextScope *sc_scope,
                           lldb::TypeClass type_mask, TypeList &type_list);
public:
   virtual void SectionFileAddressesChanged();
 
   // PluginInterface protocol
   ConstString GetPluginName() override;
 
   uint32_t GetPluginVersion() override;
 
 protected:
-  // Classes that inherit from SymbolVendor can see and modify these
-  typedef std::vector<lldb::CompUnitSP> CompileUnits;
-  typedef CompileUnits::iterator CompileUnitIter;
-  typedef CompileUnits::const_iterator CompileUnitConstIter;
-
   TypeList m_type_list; // Uniqued types for all parsers owned by this module
-  CompileUnits m_compile_units;    // The current compile units
   lldb::ObjectFileSP m_objfile_sp; // Keep a reference to the object file in
                                    // case it isn't the same as the module
                                    // object file (debug symbols in a separate
                                    // file)
   std::unique_ptr<SymbolFile> m_sym_file_up; // A single symbol file. Subclasses
                                              // can add more of these if needed.
   Symtab *m_symtab; // Save a symtab once to not pass it through `AddSymbols` of
                     // the symbol file each time when it is needed

source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.h

public:
   ~SymbolFileBreakpad() override {}
 
   uint32_t CalculateAbilities() override;
 
   void InitializeObject() override {}
 
   // Compile Unit function calls
 
-  uint32_t GetNumCompileUnits() override;
-
-  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
-
   lldb::LanguageType ParseLanguage(CompileUnit &comp_unit) override {
     return lldb::eLanguageTypeUnknown;
   }
 
   size_t ParseFunctions(CompileUnit &comp_unit) override;
 
   bool ParseLineTable(CompileUnit &comp_unit) override;
 
public:
     }
 
     Bookmark bookmark;
     llvm::Optional<FileSpecList> support_files;
     std::unique_ptr<LineTable> line_table_up;
 
   };
 
-  SymbolVendor &GetSymbolVendor();
+  uint32_t CalculateNumCompileUnits() override;
+  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
+
   lldb::addr_t GetBaseFileAddress();
   void ParseFileRecords();
   void ParseCUData();
   void ParseLineTableAndSupportFiles(CompileUnit &cu, CompUnitData &data);
   void ParseUnwindData();
   bool ParseUnwindRow(llvm::StringRef unwind_rules,
                       const RegisterInfoResolver &resolver,
                       UnwindPlan::Row &row);

source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.cpp

uint32_t SymbolFileBreakpad::CalculateAbilities() {
   if (!m_obj_file)
     return 0;
   if (m_obj_file->GetPluginName() != ObjectFileBreakpad::GetPluginNameStatic())
     return 0;
 
   return CompileUnits | Functions | LineTables;
 }
 
-uint32_t SymbolFileBreakpad::GetNumCompileUnits() {
+uint32_t SymbolFileBreakpad::CalculateNumCompileUnits() {
   ParseCUData();
   return m_cu_data->GetSize();
 }
 
 CompUnitSP SymbolFileBreakpad::ParseCompileUnitAtIndex(uint32_t index) {
   if (index >= m_cu_data->GetSize())
     return nullptr;
 
if (record && record->FileNum < m_files->size())
       spec = (*m_files)[record->FileNum];
   }
 
   auto cu_sp = std::make_shared<CompileUnit>(m_obj_file->GetModule(),
                                              /*user_data*/ nullptr, spec, index,
                                              eLanguageTypeUnknown,
                                              /*is_optimized*/ eLazyBoolNo);
 
-  GetSymbolVendor().SetCompileUnitAtIndex(index, cu_sp);
+  SetCompileUnitAtIndex(index, cu_sp);
   return cu_sp;
 }
 
 size_t SymbolFileBreakpad::ParseFunctions(CompileUnit &comp_unit) {
   // TODO
   return 0;
 }
 
if (!(resolve_scope & (eSymbolContextCompUnit | eSymbolContextLineEntry)))
     return 0;
 
   ParseCUData();
   uint32_t idx =
       m_cu_data->FindEntryIndexThatContains(so_addr.GetFileAddress());
   if (idx == UINT32_MAX)
     return 0;
 
-  sc.comp_unit = GetSymbolVendor().GetCompileUnitAtIndex(idx).get();
+  sc.comp_unit = GetCompileUnitAtIndex(idx).get();
   SymbolContextItem result = eSymbolContextCompUnit;
   if (resolve_scope & eSymbolContextLineEntry) {
     if (sc.comp_unit->GetLineTable()->FindLineEntryByAddress(so_addr,
                                                              sc.line_entry)) {
       result |= eSymbolContextLineEntry;
     }
   }
 
   return result;
 }
 
 uint32_t SymbolFileBreakpad::ResolveSymbolContext(
     const FileSpec &file_spec, uint32_t line, bool check_inlines,
     lldb::SymbolContextItem resolve_scope, SymbolContextList &sc_list) {
   if (!(resolve_scope & eSymbolContextCompUnit))
     return 0;
 
   uint32_t old_size = sc_list.GetSize();
   for (size_t i = 0, size = GetNumCompileUnits(); i < size; ++i) {
-    CompileUnit &cu = *GetSymbolVendor().GetCompileUnitAtIndex(i);
+    CompileUnit &cu = *GetCompileUnitAtIndex(i);
     cu.ResolveSymbolContext(file_spec, line, check_inlines,
                             /*exact*/ false, resolve_scope, sc_list);
   }
   return sc_list.GetSize() - old_size;
 }
 
 uint32_t SymbolFileBreakpad::FindFunctions(
     ConstString name, const CompilerDeclContext *parent_decl_ctx,
for (++It; It != End; ++It) {
     row_sp->SetOffset(record->Address - init_record->Address);
     if (!ParseUnwindRow(record->UnwindRules, resolver, *row_sp))
       return nullptr;
     plan_sp->AppendRow(row_sp);
   }
   return plan_sp;
 }
 
-SymbolVendor &SymbolFileBreakpad::GetSymbolVendor() {
-  return *m_obj_file->GetModule()->GetSymbolVendor();
-}
-
 addr_t SymbolFileBreakpad::GetBaseFileAddress() {
   return m_obj_file->GetModule()
       ->GetObjectFile()
       ->GetBaseAddress()
       .GetFileAddress();
 }
 
 // Parse out all the FILE records from the breakpad file. These will be needed

source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h

public:
   ~SymbolFileDWARF() override;
 
   uint32_t CalculateAbilities() override;
 
   void InitializeObject() override;
 
   // Compile Unit function calls
 
-  uint32_t GetNumCompileUnits() override;
-
-  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
-
   lldb::LanguageType
   ParseLanguage(lldb_private::CompileUnit &comp_unit) override;
 
   size_t ParseFunctions(lldb_private::CompileUnit &comp_unit) override;
 
   bool ParseLineTable(lldb_private::CompileUnit &comp_unit) override;
 
   bool ParseDebugMacros(lldb_private::CompileUnit &comp_unit) override;
GetCachedSectionData(lldb::SectionType sect_type,
                        DWARFDataSegment &data_segment);
 
   virtual void LoadSectionData(lldb::SectionType sect_type,
                                lldb_private::DWARFDataExtractor &data);
 
   bool DeclContextMatchesThisSymbolFile(
       const lldb_private::CompilerDeclContext *decl_ctx);
 
+  uint32_t CalculateNumCompileUnits() override;
+
+  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
+
   virtual DWARFUnit *
   GetDWARFCompileUnit(lldb_private::CompileUnit *comp_unit);
 
   DWARFUnit *GetNextUnparsedDWARFCompileUnit(DWARFUnit *prev_cu);
 
   bool GetFunction(const DWARFDIE &die, lldb_private::SymbolContext &sc);
 
   lldb_private::Function *ParseFunction(lldb_private::CompileUnit &comp_unit,

source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp

if (&dwarf_cu.GetSymbolFileDWARF() != this) {
           BuildCuTranslationTable();
           cu_sp = std::make_shared<CompileUnit>(
               module_sp, &dwarf_cu, cu_file_spec,
               *GetDWARFUnitIndex(dwarf_cu.GetID()), cu_language,
               is_optimized ? eLazyBoolYes : eLazyBoolNo);
 
           dwarf_cu.SetUserData(cu_sp.get());
 
-          m_obj_file->GetModule()->GetSymbolVendor()->SetCompileUnitAtIndex(
-              dwarf_cu.GetID(), cu_sp);
+          SetCompileUnitAtIndex(dwarf_cu.GetID(), cu_sp);
         }
       }
     }
   }
   return cu_sp;
 }
 
 void SymbolFileDWARF::BuildCuTranslationTable() {
llvm::Optional<uint32_t> SymbolFileDWARF::GetDWARFUnitIndex(uint32_t cu_idx) {
   BuildCuTranslationTable();
   if (m_lldb_cu_to_dwarf_unit.empty())
     return cu_idx;
   if (cu_idx >= m_lldb_cu_to_dwarf_unit.size())
     return llvm::None;
   return m_lldb_cu_to_dwarf_unit[cu_idx];
 }
 
-uint32_t SymbolFileDWARF::GetNumCompileUnits() {
+uint32_t SymbolFileDWARF::CalculateNumCompileUnits() {
   DWARFDebugInfo *info = DebugInfo();
   if (!info)
     return 0;
   BuildCuTranslationTable();
   return m_lldb_cu_to_dwarf_unit.empty() ? info->GetNumUnits()
                                          : m_lldb_cu_to_dwarf_unit.size();
 }
 
SymbolFileDWARF::ParseCallEdgesInFunction(UserID func_id) {
   return {};
 }
 
 // PluginInterface protocol
 ConstString SymbolFileDWARF::GetPluginName() { return GetPluginNameStatic(); }
 
 uint32_t SymbolFileDWARF::GetPluginVersion() { return 1; }
 
-void SymbolFileDWARF::Dump(lldb_private::Stream &s) { m_index->Dump(s); }
+void SymbolFileDWARF::Dump(lldb_private::Stream &s) {
+  SymbolFile::Dump(s);
+  m_index->Dump(s);
+}
 
 void SymbolFileDWARF::DumpClangAST(Stream &s) {
   TypeSystem *ts = GetTypeSystemForLanguage(eLanguageTypeC_plus_plus);
   ClangASTContext *clang = llvm::dyn_cast_or_null<ClangASTContext>(ts);
   if (!clang)
     return;
   clang->Dump(s);
 }

source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h

public:
   // Constructors and Destructors
   SymbolFileDWARFDebugMap(lldb_private::ObjectFile *ofile);
   ~SymbolFileDWARFDebugMap() override;
 
   uint32_t CalculateAbilities() override;
   void InitializeObject() override;
 
   // Compile Unit function calls
-  uint32_t GetNumCompileUnits() override;
-  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
-
   lldb::LanguageType
   ParseLanguage(lldb_private::CompileUnit &comp_unit) override;
 
   size_t ParseFunctions(lldb_private::CompileUnit &comp_unit) override;
 
   bool ParseLineTable(lldb_private::CompileUnit &comp_unit) override;
 
   bool ParseDebugMacros(lldb_private::CompileUnit &comp_unit) override;
CompileUnitInfo()
           file_range_map(), file_range_map_valid(false) {}
 
     const FileRangeMap &GetFileRangeMap(SymbolFileDWARFDebugMap *exe_symfile);
   };
 
   // Protected Member Functions
   void InitOSO();
 
+  uint32_t CalculateNumCompileUnits() override;
+  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
+
   static uint32_t GetOSOIndexFromUserID(lldb::user_id_t uid) {
     return (uint32_t)((uid >> 32ull) - 1ull);
   }
 
   static SymbolFileDWARF *GetSymbolFileAsSymbolFileDWARF(SymbolFile *sym_file);
 
   bool GetFileSpecForSO(uint32_t oso_idx, lldb_private::FileSpec &file_spec);
 

source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.cpp

if (!m_compile_unit_infos.empty()) {
              SymbolFile::Blocks | SymbolFile::GlobalVariables |
              SymbolFile::LocalVariables | SymbolFile::VariableTypes |
              SymbolFile::LineTables;
     }
   }
   return 0;
 }
 
-uint32_t SymbolFileDWARFDebugMap::GetNumCompileUnits() {
+uint32_t SymbolFileDWARFDebugMap::CalculateNumCompileUnits() {
   InitOSO();
   return m_compile_unit_infos.size();
 }
 
 CompUnitSP SymbolFileDWARFDebugMap::ParseCompileUnitAtIndex(uint32_t cu_idx) {
   CompUnitSP comp_unit_sp;
   const uint32_t cu_count = GetNumCompileUnits();
 
   if (cu_idx < cu_count) {
     Module *oso_module = GetModuleByCompUnitInfo(&m_compile_unit_infos[cu_idx]);
     if (oso_module) {
       FileSpec so_file_spec;
       if (GetFileSpecForSO(cu_idx, so_file_spec)) {
         // User zero as the ID to match the compile unit at offset zero in each
         // .o file since each .o file can only have one compile unit for now.
         lldb::user_id_t cu_id = 0;
         m_compile_unit_infos[cu_idx].compile_unit_sp =
             std::make_shared<CompileUnit>(
                 m_obj_file->GetModule(), nullptr, so_file_spec, cu_id,
                 eLanguageTypeUnknown, eLazyBoolCalculate);
 
         if (m_compile_unit_infos[cu_idx].compile_unit_sp) {
-          // Let our symbol vendor know about this compile unit
-          m_obj_file->GetModule()->GetSymbolVendor()->SetCompileUnitAtIndex(
-              cu_idx, m_compile_unit_infos[cu_idx].compile_unit_sp);
+          SetCompileUnitAtIndex(cu_idx,
+                                m_compile_unit_infos[cu_idx].compile_unit_sp);
         }
       }
     }
     comp_unit_sp = m_compile_unit_infos[cu_idx].compile_unit_sp;
   }
 
   return comp_unit_sp;
 }
for (uint32_t cu_idx = 0; cu_idx < cu_count; ++cu_idx) {
       SymbolFileDWARF *oso_symfile =
           GetSymbolFileByCompUnitInfo(&m_compile_unit_infos[cu_idx]);
       if (oso_symfile == oso_dwarf) {
         if (m_compile_unit_infos[cu_idx].compile_unit_sp) {
           assert(m_compile_unit_infos[cu_idx].compile_unit_sp.get() ==
                  cu_sp.get());
         } else {
           m_compile_unit_infos[cu_idx].compile_unit_sp = cu_sp;
-          m_obj_file->GetModule()->GetSymbolVendor()->SetCompileUnitAtIndex(
-              cu_idx, cu_sp);
+          SetCompileUnitAtIndex(cu_idx, cu_sp);
         }
       }
     }
   }
 }
 
 CompilerDeclContext
 SymbolFileDWARFDebugMap::GetDeclContextForUID(lldb::user_id_t type_uid) {

source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.h

public:
   ~SymbolFileNativePDB() override;
 
   uint32_t CalculateAbilities() override;
 
   void InitializeObject() override;
 
   // Compile Unit function calls
 
-  uint32_t GetNumCompileUnits() override;
-
   void
   ParseDeclsForContext(lldb_private::CompilerDeclContext decl_ctx) override;
 
-  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
-
   lldb::LanguageType
   ParseLanguage(lldb_private::CompileUnit &comp_unit) override;
 
   size_t ParseFunctions(lldb_private::CompileUnit &comp_unit) override;
 
   bool ParseLineTable(lldb_private::CompileUnit &comp_unit) override;
 
   bool ParseDebugMacros(lldb_private::CompileUnit &comp_unit) override;
public:
   uint32_t GetPluginVersion() override;
 
   llvm::pdb::PDBFile &GetPDBFile() { return m_index->pdb(); }
   const llvm::pdb::PDBFile &GetPDBFile() const { return m_index->pdb(); }
 
   void DumpClangAST(Stream &s) override;
 
 private:
+  uint32_t CalculateNumCompileUnits() override;
+
+  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
 
   size_t FindTypesByName(llvm::StringRef name, uint32_t max_matches,
                          TypeMap &types);
 
   lldb::TypeSP CreateModifierType(PdbTypeSymId type_id,
                                   const llvm::codeview::ModifierRecord &mr,
                                   CompilerType ct);
   lldb::TypeSP CreatePointerType(PdbTypeSymId type_id,

source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp

void SymbolFileNativePDB::InitializeObject() {
   TypeSystem *ts = m_obj_file->GetModule()->GetTypeSystemForLanguage(
       lldb::eLanguageTypeC_plus_plus);
   if (ts)
     ts->SetSymbolFile(this);
 
   m_ast = llvm::make_unique<PdbAstBuilder>(*m_obj_file, *m_index);
 }
 
-uint32_t SymbolFileNativePDB::GetNumCompileUnits() {
+uint32_t SymbolFileNativePDB::CalculateNumCompileUnits() {
   const DbiModuleList &modules = m_index->dbi().modules();
   uint32_t count = modules.getModuleCount();
   if (count == 0)
     return count;
 
   // The linker can inject an additional "dummy" compilation unit into the
   // PDB. Ignore this special compile unit for our purposes, if it is there.
   // It is always the last one.
SymbolFileNativePDB::CreateCompileUnit(const CompilandIndexItem &cci) {
   llvm::SmallString<64> source_file_name =
       m_index->compilands().GetMainSourceFile(cci);
   FileSpec fs(source_file_name);
 
   CompUnitSP cu_sp =
       std::make_shared<CompileUnit>(m_obj_file->GetModule(), nullptr, fs,
                                     toOpaqueUid(cci.m_id), lang, optimized);
 
-  m_obj_file->GetModule()->GetSymbolVendor()->SetCompileUnitAtIndex(
-      cci.m_id.modi, cu_sp);
+  SetCompileUnitAtIndex(cci.m_id.modi, cu_sp);
   return cu_sp;
 }
 
 lldb::TypeSP SymbolFileNativePDB::CreateModifierType(PdbTypeSymId type_id,
                                                      const ModifierRecord &mr,
                                                      CompilerType ct) {
   TpiStream &stream = m_index->tpi();
 

source/Plugins/SymbolFile/PDB/SymbolFilePDB.h

public:
   ~SymbolFilePDB() override;
 
   uint32_t CalculateAbilities() override;
 
   void InitializeObject() override;
 
   // Compile Unit function calls
 
-  uint32_t GetNumCompileUnits() override;
-
-  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
-
   lldb::LanguageType
   ParseLanguage(lldb_private::CompileUnit &comp_unit) override;
 
   size_t ParseFunctions(lldb_private::CompileUnit &comp_unit) override;
 
   bool ParseLineTable(lldb_private::CompileUnit &comp_unit) override;
 
   bool ParseDebugMacros(lldb_private::CompileUnit &comp_unit) override;

 private:
   struct SecContribInfo {
     uint32_t Offset;
     uint32_t Size;
     uint32_t CompilandId;
   };
   using SecContribsMap = std::map<uint32_t, std::vector<SecContribInfo>>;
 
+  uint32_t CalculateNumCompileUnits() override;
+
+  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
+
   lldb::CompUnitSP ParseCompileUnitForUID(uint32_t id,
                                           uint32_t index = UINT32_MAX);
 
   bool ParseCompileUnitLineTable(lldb_private::CompileUnit &comp_unit,
                                  uint32_t match_line);
 
   void BuildSupportFileIdToSupportFileIndexMap(
       const llvm::pdb::PDBSymbolCompiland &pdb_compiland,
private:
   llvm::DenseMap<uint32_t, lldb::VariableSP> m_variables;
   llvm::DenseMap<uint64_t, std::string> m_public_names;
 
   SecContribsMap m_sec_contribs;
 
   std::vector<lldb::TypeSP> m_builtin_types;
   std::unique_ptr<llvm::pdb::IPDBSession> m_session_up;
   std::unique_ptr<llvm::pdb::PDBSymbolExe> m_global_scope_up;
-  uint32_t m_cached_compile_unit_count;
 
   lldb_private::UniqueCStringMap<uint32_t> m_func_full_names;
   lldb_private::UniqueCStringMap<uint32_t> m_func_base_names;
   lldb_private::UniqueCStringMap<uint32_t> m_func_method_names;
 };
 
 #endif // lldb_Plugins_SymbolFile_PDB_SymbolFilePDB_h_

source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp

 }
 
 lldb_private::SymbolFile *
 SymbolFilePDB::CreateInstance(lldb_private::ObjectFile *obj_file) {
   return new SymbolFilePDB(obj_file);
 }
 
 SymbolFilePDB::SymbolFilePDB(lldb_private::ObjectFile *object_file)
-    : SymbolFile(object_file), m_session_up(), m_global_scope_up(),
-      m_cached_compile_unit_count(0) {}
+    : SymbolFile(object_file), m_session_up(), m_global_scope_up() {}
 
 SymbolFilePDB::~SymbolFilePDB() {}
 
 uint32_t SymbolFilePDB::CalculateAbilities() {
   uint32_t abilities = 0;
   if (!m_obj_file)
     return 0;
 
void SymbolFilePDB::InitializeObject() {
   lldb::addr_t obj_load_address = m_obj_file->GetBaseAddress().GetFileAddress();
   lldbassert(obj_load_address && obj_load_address != LLDB_INVALID_ADDRESS);
   m_session_up->setLoadAddress(obj_load_address);
   if (!m_global_scope_up)
     m_global_scope_up = m_session_up->getGlobalScope();
   lldbassert(m_global_scope_up.get());
 }
 
-uint32_t SymbolFilePDB::GetNumCompileUnits() {
-  if (m_cached_compile_unit_count == 0) {
-    auto compilands = m_global_scope_up->findAllChildren<PDBSymbolCompiland>();
-    if (!compilands)
-      return 0;
+uint32_t SymbolFilePDB::CalculateNumCompileUnits() {
 
-    // The linker could link *.dll (compiland language = LINK), or import
-    // *.dll. For example, a compiland with name `Import:KERNEL32.dll` could be
-    // found as a child of the global scope (PDB executable). Usually, such
-    // compilands contain `thunk` symbols in which we are not interested for
-    // now. However we still count them in the compiland list. If we perform
-    // any compiland related activity, like finding symbols through
-    // llvm::pdb::IPDBSession methods, such compilands will all be searched
-    // automatically no matter whether we include them or not.
-    m_cached_compile_unit_count = compilands->getChildCount();
+  uint32_t compile_unit_count = compilands->getChildCount();
 
-    // The linker can inject an additional "dummy" compilation unit into the
-    // PDB. Ignore this special compile unit for our purposes, if it is there.
-    // It is always the last one.
-    auto last_compiland_up =
-        compilands->getChildAtIndex(m_cached_compile_unit_count - 1);
-    lldbassert(last_compiland_up.get());
-    std::string name = last_compiland_up->getName();
-    if (name == "* Linker *")
-      --m_cached_compile_unit_count;
-  }
-  return m_cached_compile_unit_count;
+  auto last_compiland_up = compilands->getChildAtIndex(compile_unit_count - 1);
+    --compile_unit_count;
+  return compile_unit_count;
 }
 
 void SymbolFilePDB::GetCompileUnitIndex(
     const llvm::pdb::PDBSymbolCompiland &pdb_compiland, uint32_t &index) {
   auto results_up = m_global_scope_up->findAllChildren<PDBSymbolCompiland>();
   if (!results_up)
     return;
   auto uid = pdb_compiland.getSymIndexId();
lldb::CompUnitSP SymbolFilePDB::ParseCompileUnitForUID(uint32_t id,
 
   if (!cu_sp)
     return CompUnitSP();
 
   m_comp_units.insert(std::make_pair(id, cu_sp));
   if (index == UINT32_MAX)
     GetCompileUnitIndex(*compiland_up, index);
   lldbassert(index != UINT32_MAX);
-  m_obj_file->GetModule()->GetSymbolVendor()->SetCompileUnitAtIndex(index,
-                                                                    cu_sp);
+  SetCompileUnitAtIndex(index, cu_sp);
   return cu_sp;
 }
 
 bool SymbolFilePDB::ParseCompileUnitLineTable(CompileUnit &comp_unit,
                                               uint32_t match_line) {
   auto compiland_up = GetPDBCompilandByUID(comp_unit.GetID());
   if (!compiland_up)
     return false;

source/Plugins/SymbolFile/Symtab/SymbolFileSymtab.h

public:
   static const char *GetPluginDescriptionStatic();
 
   static lldb_private::SymbolFile *
   CreateInstance(lldb_private::ObjectFile *obj_file);
 
   uint32_t CalculateAbilities() override;
 
   // Compile Unit function calls
-  uint32_t GetNumCompileUnits() override;
-
-  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
-
   lldb::LanguageType
   ParseLanguage(lldb_private::CompileUnit &comp_unit) override;
 
   size_t ParseFunctions(lldb_private::CompileUnit &comp_unit) override;
 
   bool ParseLineTable(lldb_private::CompileUnit &comp_unit) override;
 
   bool ParseDebugMacros(lldb_private::CompileUnit &comp_unit) override;
size_t GetTypes(lldb_private::SymbolContextScope *sc_scope,
                   lldb_private::TypeList &type_list) override;
 
   // PluginInterface protocol
   lldb_private::ConstString GetPluginName() override;
 
   uint32_t GetPluginVersion() override;
 
 protected:
+  uint32_t CalculateNumCompileUnits() override;
+
+  lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
+
   typedef std::map<lldb_private::ConstString, lldb::TypeSP> TypeMap;
 
   lldb_private::Symtab::IndexCollection m_source_indexes;
   lldb_private::Symtab::IndexCollection m_func_indexes;
   lldb_private::Symtab::IndexCollection m_code_indexes;
   lldb_private::Symtab::IndexCollection m_data_indexes;
   lldb_private::Symtab::NameToIndexMap m_objc_class_name_to_index;
   TypeMap m_objc_class_types;
 
 private:
   DISALLOW_COPY_AND_ASSIGN(SymbolFileSymtab);
 };
 
 #endif // liblldb_SymbolFileSymtab_h_

source/Plugins/SymbolFile/Symtab/SymbolFileSymtab.cpp

if (symtab) {
                                        m_objc_class_name_to_index);
         m_objc_class_name_to_index.Sort();
       }
     }
   }
   return abilities;
 }
 
-uint32_t SymbolFileSymtab::GetNumCompileUnits() {
+uint32_t SymbolFileSymtab::CalculateNumCompileUnits() {
   // If we don't have any source file symbols we will just have one compile
   // unit for the entire object file
   if (m_source_indexes.empty())
     return 0;
 
   // If we have any source file symbols we will logically organize the object
   // symbols using these.
   return m_source_indexes.size();

source/Symbol/SymbolFile.cpp

 //===-- SymbolFile.cpp ------------------------------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 #include "lldb/Symbol/SymbolFile.h"
 
 #include "lldb/Core/Module.h"
 #include "lldb/Core/PluginManager.h"
+#include "lldb/Symbol/CompileUnit.h"
 #include "lldb/Symbol/ObjectFile.h"
 #include "lldb/Symbol/TypeMap.h"
 #include "lldb/Symbol/TypeSystem.h"
 #include "lldb/Symbol/VariableList.h"
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/StreamString.h"
 #include "lldb/lldb-private.h"
 
 #include <future>
 
 using namespace lldb_private;
+using namespace lldb;
 
 void SymbolFile::PreloadSymbols() {
   // No-op for most implementations.
 }
 
 std::recursive_mutex &SymbolFile::GetModuleMutex() const {
   return GetObjectFile()->GetModule()->GetMutex();
 }
#if defined(LLDB_CONFIGURATION_DEBUG)
   // guarantee correctness.
   assert(std::async(std::launch::async,
                     [this] { return this->GetModuleMutex().try_lock(); })
                  .get() == false &&
          "Module is not locked");
 #endif
 }
 
+uint32_t SymbolFile::GetNumCompileUnits() {
+  std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
+  if (!m_compile_units) {
+    // Create an array of compile unit shared pointers -- which will each
+    // remain NULL until someone asks for the actual compile unit information.
+    m_compile_units.emplace(CalculateNumCompileUnits());
+  }
+  return m_compile_units->size();
+}
+
+CompUnitSP SymbolFile::GetCompileUnitAtIndex(uint32_t idx) {
+  uint32_t num = GetNumCompileUnits();
+  if (idx >= num)
+    return nullptr;
+  lldb::CompUnitSP &cu_sp = (*m_compile_units)[idx];
+  if (!cu_sp)
+    cu_sp = ParseCompileUnitAtIndex(idx);
+  return cu_sp;
+}
+
+void SymbolFile::SetCompileUnitAtIndex(uint32_t idx, const CompUnitSP &cu_sp) {
+  std::lock_guard<std::recursive_mutex> guard(GetModuleMutex());
+  const size_t num_compile_units = GetNumCompileUnits();
+  assert(idx < num_compile_units);
+
+  // Fire off an assertion if this compile unit already exists for now. The
+  // partial parsing should take care of only setting the compile unit
+  // once, so if this assertion fails, we need to make sure that we don't
+  // have a race condition, or have a second parse of the same compile
+  // unit.
+  assert((*m_compile_units)[idx] == nullptr);
+  (*m_compile_units)[idx] = cu_sp;
+}
+
+void SymbolFile::Dump(Stream &s) {
+  s.PutCString("Compile units:\n");
+  if (m_compile_units) {
+    for (const CompUnitSP &cu_sp : *m_compile_units) {
+      // We currently only dump the compile units that have been parsed
+      if (cu_sp)
+        cu_sp->Dump(&s, /*show_context*/ false);
+    }
+  }
+  s.PutChar('\n');
+}
+
 SymbolFile::RegisterInfoResolver::~RegisterInfoResolver() = default;

source/Symbol/SymbolVendor.cpp

if (!sym_objfile_sp)
     sym_objfile_sp = module_sp->GetObjectFile()->shared_from_this();
   instance_up.reset(new SymbolVendor(module_sp));
   instance_up->AddSymbolFileRepresentation(sym_objfile_sp);
   return instance_up.release();
 }
 
 // SymbolVendor constructor
 SymbolVendor::SymbolVendor(const lldb::ModuleSP &module_sp)
-    : ModuleChild(module_sp), m_type_list(), m_compile_units(), m_sym_file_up(),
-      m_symtab() {}
+    : ModuleChild(module_sp), m_type_list(), m_sym_file_up(), m_symtab() {}
 
 // Destructor
 SymbolVendor::~SymbolVendor() {}
 
 // Add a representation given an object file.
 void SymbolVendor::AddSymbolFileRepresentation(const ObjectFileSP &objfile_sp) {
   ModuleSP module_sp(GetModule());
   if (module_sp) {
     std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
     if (objfile_sp) {
       m_objfile_sp = objfile_sp;
       m_sym_file_up.reset(SymbolFile::FindPlugin(objfile_sp.get()));
     }
   }
 }
 
-bool SymbolVendor::SetCompileUnitAtIndex(size_t idx, const CompUnitSP &cu_sp) {
-  ModuleSP module_sp(GetModule());
-  if (module_sp) {
-    std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
-    const size_t num_compile_units = GetNumCompileUnits();
-    if (idx < num_compile_units) {
-      // Fire off an assertion if this compile unit already exists for now. The
-      // partial parsing should take care of only setting the compile unit
-      // once, so if this assertion fails, we need to make sure that we don't
-      // have a race condition, or have a second parse of the same compile
-      // unit.
-      assert(m_compile_units[idx].get() == nullptr);
-      m_compile_units[idx] = cu_sp;
-      return true;
-    } else {
-      // This should NOT happen, and if it does, we want to crash and know
-      // about it
-      assert(idx < num_compile_units);
-    }
-  }
-  return false;
-}
-
 size_t SymbolVendor::GetNumCompileUnits() {
   ModuleSP module_sp(GetModule());
   if (module_sp) {
     std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
-    if (m_compile_units.empty()) {
-      if (m_sym_file_up) {
-        // Resize our array of compile unit shared pointers -- which will each
-        // remain NULL until someone asks for the actual compile unit
-        // information. When this happens, the symbol file will be asked to
-        // parse this compile unit information.
-        m_compile_units.resize(m_sym_file_up->GetNumCompileUnits());
-      }
-    }
+    if (m_sym_file_up)
+      return m_sym_file_up->GetNumCompileUnits();
   }
-  return m_compile_units.size();
+  return 0;
 }
 
 lldb::LanguageType SymbolVendor::ParseLanguage(CompileUnit &comp_unit) {
   ModuleSP module_sp(GetModule());
   if (module_sp) {
     std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
     if (m_sym_file_up)
       return m_sym_file_up->ParseLanguage(comp_unit);
if (m_sym_file_up) {
       }
     }
     s->EOL();
     if (m_sym_file_up)
       m_sym_file_up->Dump(*s);
     s->IndentMore();
     m_type_list.Dump(s, show_context);
 
-    CompileUnitConstIter cu_pos, cu_end;
-    cu_end = m_compile_units.end();
-    for (cu_pos = m_compile_units.begin(); cu_pos != cu_end; ++cu_pos) {
-      // We currently only dump the compile units that have been parsed
-      if (*cu_pos)
-        (*cu_pos)->Dump(s, show_context);
-    }
-
     if (Symtab *symtab = GetSymtab())
       symtab->Dump(s, nullptr, eSortOrderNone);
 
     s->IndentLess();
   }
 }
 
 CompUnitSP SymbolVendor::GetCompileUnitAtIndex(size_t idx) {
-  CompUnitSP cu_sp;
   ModuleSP module_sp(GetModule());
   if (module_sp) {
     std::lock_guard<std::recursive_mutex> guard(module_sp->GetMutex());
-    const size_t num_compile_units = GetNumCompileUnits();
-    if (idx < num_compile_units) {
-      cu_sp = m_compile_units[idx];
-      if (cu_sp.get() == nullptr) {
-        m_compile_units[idx] = m_sym_file_up->ParseCompileUnitAtIndex(idx);
-        cu_sp = m_compile_units[idx];
-      }
-    }
+    if (m_sym_file_up)
+      return m_sym_file_up->GetCompileUnitAtIndex(idx);
   }
-  return cu_sp;
+  return nullptr;
 }
 
 FileSpec SymbolVendor::GetMainFileSpec() const {
   if (m_sym_file_up) {
     const ObjectFile *symfile_objfile = m_sym_file_up->GetObjectFile();
     if (symfile_objfile)
       return symfile_objfile->GetFileSpec();
   }

tools/lldb-test/lldb-test.cpp

Error opts::symbols::verify(lldb_private::Module &Module) {
   if (!symfile)
     return make_string_error("Module has no symbol file.");
 
   uint32_t comp_units_count = symfile->GetNumCompileUnits();
 
   outs() << "Found " << comp_units_count << " compile units.\n";
 
   for (uint32_t i = 0; i < comp_units_count; i++) {
-    lldb::CompUnitSP comp_unit = symfile->ParseCompileUnitAtIndex(i);
+    lldb::CompUnitSP comp_unit = symfile->GetCompileUnitAtIndex(i);
     if (!comp_unit)
       return make_string_error("Connot parse compile unit {0}.", i);
 
     outs() << "Processing '" << comp_unit->GetFilename().AsCString()
            << "' compile unit.\n";
 
     LineTable *lt = comp_unit->GetLineTable();
     if (!lt)