Reapply [lldb][DWARF] Delay struct/class/union definition DIE searching when parsing declaration DIEs. (#92328)

This reapplies
9a7262c
(#90663) and added #91808 as a
fix.

It was causing tests on macos to fail because
`SymbolFileDWARF::GetForwardDeclCompilerTypeToDIE` returned the map
owned by this symol file. When there were two symbol files, two
different maps were created for caching from compiler type to DIE even
if they are for the same module. The solution is to do the same as
`SymbolFileDWARF::GetUniqueDWARFASTTypeMap`: inquery
SymbolFileDWARFDebugMap first to get the shared underlying SymbolFile so
the map is shared among multiple SymbolFileDWARF.

Author: ZequanWu

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParser.h

@@ -60,6 +60,8 @@ class DWARFASTParser {
 
   virtual ConstString GetDIEClassTemplateParams(const DWARFDIE &die) = 0;
 
+  virtual lldb_private::Type *FindDefinitionTypeForDIE(const DWARFDIE &die) = 0;
+
   static std::optional<SymbolFile::ArrayInfo>
   ParseChildArrayInfo(const DWARFDIE &parent_die,
                       const ExecutionContext *exe_ctx = nullptr);

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp

@@ -87,6 +87,10 @@ bool DebugNamesDWARFIndex::ProcessEntry(
   DWARFDIE die = dwarf.GetDIE(*ref);
   if (!die)
     return true;
+  // Clang erroneously emits index entries for declaration DIEs in case when the
+  // definition is in a type unit (llvm.org/pr77696). Weed those out.
+  if (die.GetAttributeValueAsUnsigned(DW_AT_declaration, 0))
+    return true;
   return callback(die);
 }
 

lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.h

@@ -481,6 +481,13 @@ static ConstString GetDWARFMachOSegmentName() {
   return g_dwarf_section_name;
 }
 
+llvm::DenseMap<lldb::opaque_compiler_type_t, DIERef> &
+SymbolFileDWARF::GetForwardDeclCompilerTypeToDIE() {
+  if (SymbolFileDWARFDebugMap *debug_map_symfile = GetDebugMapSymfile())
+    return debug_map_symfile->GetForwardDeclCompilerTypeToDIE();
+  return m_forward_decl_compiler_type_to_die;
+}
+
 UniqueDWARFASTTypeMap &SymbolFileDWARF::GetUniqueDWARFASTTypeMap() {
   SymbolFileDWARFDebugMap *debug_map_symfile = GetDebugMapSymfile();
   if (debug_map_symfile)
@@ -1632,27 +1639,33 @@ bool SymbolFileDWARF::CompleteType(CompilerType &compiler_type) {
     return true;
   }
 
-  DWARFDIE dwarf_die = GetDIE(die_it->getSecond());
-  if (dwarf_die) {
-    // Once we start resolving this type, remove it from the forward
-    // declaration map in case anyone child members or other types require this
-    // type to get resolved. The type will get resolved when all of the calls
-    // to SymbolFileDWARF::ResolveClangOpaqueTypeDefinition are done.
-    GetForwardDeclCompilerTypeToDIE().erase(die_it);
-
-    Type *type = GetDIEToType().lookup(dwarf_die.GetDIE());
+  // Once we start resolving this type, remove it from the forward
+  // declaration map in case anyone's child members or other types require this
+  // type to get resolved.
+  DWARFDIE dwarf_die = GetDIE(die_it->second);
+  GetForwardDeclCompilerTypeToDIE().erase(die_it);
+  Type *type = nullptr;
+  if (DWARFASTParser *dwarf_ast = GetDWARFParser(*dwarf_die.GetCU()))
+    type = dwarf_ast->FindDefinitionTypeForDIE(dwarf_die);
+  if (!type)
+    return false;
 
-    Log *log = GetLog(DWARFLog::DebugInfo | DWARFLog::TypeCompletion);
-    if (log)
-      GetObjectFile()->GetModule()->LogMessageVerboseBacktrace(
-          log, "{0:x8}: {1} ({2}) '{3}' resolving forward declaration...",
-          dwarf_die.GetID(), DW_TAG_value_to_name(dwarf_die.Tag()),
-          dwarf_die.Tag(), type->GetName().AsCString());
-    assert(compiler_type);
-    if (DWARFASTParser *dwarf_ast = GetDWARFParser(*dwarf_die.GetCU()))
-      return dwarf_ast->CompleteTypeFromDWARF(dwarf_die, type, compiler_type);
+  die_it = GetForwardDeclCompilerTypeToDIE().find(
+      compiler_type_no_qualifiers.GetOpaqueQualType());
+  if (die_it != GetForwardDeclCompilerTypeToDIE().end()) {
+    dwarf_die = GetDIE(die_it->getSecond());
+    GetForwardDeclCompilerTypeToDIE().erase(die_it);
   }
-  return false;
+
+  if (Log *log = GetLog(DWARFLog::DebugInfo | DWARFLog::TypeCompletion))
+    GetObjectFile()->GetModule()->LogMessageVerboseBacktrace(
+        log, "{0:x8}: {1} ({2}) '{3}' resolving forward declaration...",
+        dwarf_die.GetID(), DW_TAG_value_to_name(dwarf_die.Tag()),
+        dwarf_die.Tag(), type->GetName().AsCString());
+  assert(compiler_type);
+  if (DWARFASTParser *dwarf_ast = GetDWARFParser(*dwarf_die.GetCU()))
+    return dwarf_ast->CompleteTypeFromDWARF(dwarf_die, type, compiler_type);
+  return true;
 }
 
 Type *SymbolFileDWARF::ResolveType(const DWARFDIE &die,

lldb/source/Plugins/SymbolFile/DWARF/DebugNamesDWARFIndex.cpp

@@ -335,12 +335,8 @@ class SymbolFileDWARF : public SymbolFileCommon {
 
   virtual DIEToTypePtr &GetDIEToType() { return m_die_to_type; }
 
-  typedef llvm::DenseMap<lldb::opaque_compiler_type_t, DIERef>
-      CompilerTypeToDIE;
-
-  virtual CompilerTypeToDIE &GetForwardDeclCompilerTypeToDIE() {
-    return m_forward_decl_compiler_type_to_die;
-  }
+  virtual llvm::DenseMap<lldb::opaque_compiler_type_t, DIERef> &
+  GetForwardDeclCompilerTypeToDIE();
 
   typedef llvm::DenseMap<const DWARFDebugInfoEntry *, lldb::VariableSP>
       DIEToVariableSP;
@@ -533,9 +529,14 @@ class SymbolFileDWARF : public SymbolFileCommon {
   NameToOffsetMap m_function_scope_qualified_name_map;
   std::unique_ptr<DWARFDebugRanges> m_ranges;
   UniqueDWARFASTTypeMap m_unique_ast_type_map;
+  // A map from DIE to lldb_private::Type. For record type, the key might be
+  // either declaration DIE or definition DIE.
   DIEToTypePtr m_die_to_type;
   DIEToVariableSP m_die_to_variable_sp;
-  CompilerTypeToDIE m_forward_decl_compiler_type_to_die;
+  // A map from CompilerType to the struct/class/union/enum DIE (might be a
+  // declaration or a definition) that is used to construct it.
+  llvm::DenseMap<lldb::opaque_compiler_type_t, DIERef>
+      m_forward_decl_compiler_type_to_die;
   llvm::DenseMap<dw_offset_t, std::unique_ptr<SupportFileList>>
       m_type_unit_support_files;
   std::vector<uint32_t> m_lldb_cu_to_dwarf_unit;

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp

@@ -284,6 +284,11 @@ class SymbolFileDWARFDebugMap : public SymbolFileCommon {
   lldb::TypeSP FindCompleteObjCDefinitionTypeForDIE(
       const DWARFDIE &die, ConstString type_name, bool must_be_implementation);
 
+  llvm::DenseMap<lldb::opaque_compiler_type_t, DIERef> &
+  GetForwardDeclCompilerTypeToDIE() {
+    return m_forward_decl_compiler_type_to_die;
+  }
+
   UniqueDWARFASTTypeMap &GetUniqueDWARFASTTypeMap() {
     return m_unique_ast_type_map;
   }
@@ -321,6 +326,10 @@ class SymbolFileDWARFDebugMap : public SymbolFileCommon {
   std::vector<uint32_t> m_func_indexes; // Sorted by address
   std::vector<uint32_t> m_glob_indexes;
   std::map<std::pair<ConstString, llvm::sys::TimePoint<>>, OSOInfoSP> m_oso_map;
+  // A map from CompilerType to the struct/class/union/enum DIE (might be a
+  // declaration or a definition) that is used to construct it.
+  llvm::DenseMap<lldb::opaque_compiler_type_t, DIERef>
+      m_forward_decl_compiler_type_to_die;
   UniqueDWARFASTTypeMap m_unique_ast_type_map;
   LazyBool m_supports_DW_AT_APPLE_objc_complete_type;
   DebugMap m_debug_map;

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.h

@@ -110,7 +110,7 @@ SymbolFileDWARF::DIEToVariableSP &SymbolFileDWARFDwo::GetDIEToVariable() {
   return GetBaseSymbolFile().GetDIEToVariable();
 }
 
-SymbolFileDWARF::CompilerTypeToDIE &
+llvm::DenseMap<lldb::opaque_compiler_type_t, DIERef> &
 SymbolFileDWARFDwo::GetForwardDeclCompilerTypeToDIE() {
   return GetBaseSymbolFile().GetForwardDeclCompilerTypeToDIE();
 }

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDebugMap.h

@@ -72,7 +72,8 @@ class SymbolFileDWARFDwo : public SymbolFileDWARF {
 
   DIEToVariableSP &GetDIEToVariable() override;
 
-  CompilerTypeToDIE &GetForwardDeclCompilerTypeToDIE() override;
+  llvm::DenseMap<lldb::opaque_compiler_type_t, DIERef> &
+  GetForwardDeclCompilerTypeToDIE() override;
 
   UniqueDWARFASTTypeMap &GetUniqueDWARFASTTypeMap() override;
 

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.cpp

@@ -13,66 +13,67 @@
 using namespace lldb_private::dwarf;
 using namespace lldb_private::plugin::dwarf;
 
-bool UniqueDWARFASTTypeList::Find(const DWARFDIE &die,
-                                  const lldb_private::Declaration &decl,
-                                  const int32_t byte_size,
-                                  UniqueDWARFASTType &entry) const {
-  for (const UniqueDWARFASTType &udt : m_collection) {
+UniqueDWARFASTType *UniqueDWARFASTTypeList::Find(
+    const DWARFDIE &die, const lldb_private::Declaration &decl,
+    const int32_t byte_size, bool is_forward_declaration) {
+  for (UniqueDWARFASTType &udt : m_collection) {
     // Make sure the tags match
     if (udt.m_die.Tag() == die.Tag()) {
-      // Validate byte sizes of both types only if both are valid.
-      if (udt.m_byte_size < 0 || byte_size < 0 ||
-          udt.m_byte_size == byte_size) {
-        // Make sure the file and line match
-        if (udt.m_declaration == decl) {
-          // The type has the same name, and was defined on the same file and
-          // line. Now verify all of the parent DIEs match.
-          DWARFDIE parent_arg_die = die.GetParent();
-          DWARFDIE parent_pos_die = udt.m_die.GetParent();
-          bool match = true;
-          bool done = false;
-          while (!done && match && parent_arg_die && parent_pos_die) {
-            const dw_tag_t parent_arg_tag = parent_arg_die.Tag();
-            const dw_tag_t parent_pos_tag = parent_pos_die.Tag();
-            if (parent_arg_tag == parent_pos_tag) {
-              switch (parent_arg_tag) {
-              case DW_TAG_class_type:
-              case DW_TAG_structure_type:
-              case DW_TAG_union_type:
-              case DW_TAG_namespace: {
-                const char *parent_arg_die_name = parent_arg_die.GetName();
-                if (parent_arg_die_name ==
-                    nullptr) // Anonymous (i.e. no-name) struct
-                {
-                  match = false;
-                } else {
-                  const char *parent_pos_die_name = parent_pos_die.GetName();
-                  if (parent_pos_die_name == nullptr ||
-                      ((parent_arg_die_name != parent_pos_die_name) &&
-                       strcmp(parent_arg_die_name, parent_pos_die_name)))
-                    match = false;
-                }
-              } break;
-
-              case DW_TAG_compile_unit:
-              case DW_TAG_partial_unit:
-                done = true;
-                break;
-              default:
-                break;
-              }
+      // If they are not both definition DIEs or both declaration DIEs, then
+      // don't check for byte size and declaration location, because declaration
+      // DIEs usually don't have those info.
+      bool matching_size_declaration =
+          udt.m_is_forward_declaration != is_forward_declaration
+              ? true
+              : (udt.m_byte_size < 0 || byte_size < 0 ||
+                 udt.m_byte_size == byte_size) &&
+                    udt.m_declaration == decl;
+      if (!matching_size_declaration)
+        continue;
+      // The type has the same name, and was defined on the same file and
+      // line. Now verify all of the parent DIEs match.
+      DWARFDIE parent_arg_die = die.GetParent();
+      DWARFDIE parent_pos_die = udt.m_die.GetParent();
+      bool match = true;
+      bool done = false;
+      while (!done && match && parent_arg_die && parent_pos_die) {
+        const dw_tag_t parent_arg_tag = parent_arg_die.Tag();
+        const dw_tag_t parent_pos_tag = parent_pos_die.Tag();
+        if (parent_arg_tag == parent_pos_tag) {
+          switch (parent_arg_tag) {
+          case DW_TAG_class_type:
+          case DW_TAG_structure_type:
+          case DW_TAG_union_type:
+          case DW_TAG_namespace: {
+            const char *parent_arg_die_name = parent_arg_die.GetName();
+            if (parent_arg_die_name == nullptr) {
+              // Anonymous (i.e. no-name) struct
+              match = false;
+            } else {
+              const char *parent_pos_die_name = parent_pos_die.GetName();
+              if (parent_pos_die_name == nullptr ||
+                  ((parent_arg_die_name != parent_pos_die_name) &&
+                   strcmp(parent_arg_die_name, parent_pos_die_name)))
+                match = false;
             }
-            parent_arg_die = parent_arg_die.GetParent();
-            parent_pos_die = parent_pos_die.GetParent();
-          }
+          } break;
 
-          if (match) {
-            entry = udt;
-            return true;
+          case DW_TAG_compile_unit:
+          case DW_TAG_partial_unit:
+            done = true;
+            break;
+          default:
+            break;
           }
         }
+        parent_arg_die = parent_arg_die.GetParent();
+        parent_pos_die = parent_pos_die.GetParent();
+      }
+
+      if (match) {
+        return &udt;
       }
     }
   }
-  return false;
+  return nullptr;
 }

lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARFDwo.h

@@ -23,31 +23,19 @@ class UniqueDWARFASTType {
   // Constructors and Destructors
   UniqueDWARFASTType() : m_type_sp(), m_die(), m_declaration() {}
 
-  UniqueDWARFASTType(lldb::TypeSP &type_sp, const DWARFDIE &die,
-                     const Declaration &decl, int32_t byte_size)
-      : m_type_sp(type_sp), m_die(die), m_declaration(decl),
-        m_byte_size(byte_size) {}
-
   UniqueDWARFASTType(const UniqueDWARFASTType &rhs)
       : m_type_sp(rhs.m_type_sp), m_die(rhs.m_die),
-        m_declaration(rhs.m_declaration), m_byte_size(rhs.m_byte_size) {}
+        m_declaration(rhs.m_declaration), m_byte_size(rhs.m_byte_size),
+        m_is_forward_declaration(rhs.m_is_forward_declaration) {}
 
   ~UniqueDWARFASTType() = default;
 
-  UniqueDWARFASTType &operator=(const UniqueDWARFASTType &rhs) {
-    if (this != &rhs) {
-      m_type_sp = rhs.m_type_sp;
-      m_die = rhs.m_die;
-      m_declaration = rhs.m_declaration;
-      m_byte_size = rhs.m_byte_size;
-    }
-    return *this;
-  }
-
   lldb::TypeSP m_type_sp;
   DWARFDIE m_die;
   Declaration m_declaration;
   int32_t m_byte_size = -1;
+  // True if the m_die is a forward declaration DIE.
+  bool m_is_forward_declaration = true;
 };
 
 class UniqueDWARFASTTypeList {
@@ -62,8 +50,9 @@ class UniqueDWARFASTTypeList {
     m_collection.push_back(entry);
   }
 
-  bool Find(const DWARFDIE &die, const Declaration &decl,
-            const int32_t byte_size, UniqueDWARFASTType &entry) const;
+  UniqueDWARFASTType *Find(const DWARFDIE &die, const Declaration &decl,
+                           const int32_t byte_size,
+                           bool is_forward_declaration);
 
 protected:
   typedef std::vector<UniqueDWARFASTType> collection;
@@ -80,14 +69,15 @@ class UniqueDWARFASTTypeMap {
     m_collection[name.GetCString()].Append(entry);
   }
 
-  bool Find(ConstString name, const DWARFDIE &die, const Declaration &decl,
-            const int32_t byte_size, UniqueDWARFASTType &entry) const {
+  UniqueDWARFASTType *Find(ConstString name, const DWARFDIE &die,
+                           const Declaration &decl, const int32_t byte_size,
+                           bool is_forward_declaration) {
     const char *unique_name_cstr = name.GetCString();
-    collection::const_iterator pos = m_collection.find(unique_name_cstr);
+    collection::iterator pos = m_collection.find(unique_name_cstr);
     if (pos != m_collection.end()) {
-      return pos->second.Find(die, decl, byte_size, entry);
+      return pos->second.Find(die, decl, byte_size, is_forward_declaration);
     }
-    return false;
+    return nullptr;
   }
 
 protected:

lldb/source/Plugins/SymbolFile/DWARF/UniqueDWARFASTType.cpp

@@ -0,0 +1,36 @@
+# Test definition DIE searching is delayed until complete type is required.
+
+# UNSUPPORTED: system-windows
+
+# RUN: split-file %s %t
+# RUN: %clangxx_host %t/main.cpp %t/t1_def.cpp -gdwarf -o %t.out
+# RUN: %lldb -b %t.out -s %t/lldb.cmd | FileCheck %s
+
+# CHECK: (lldb) p v1
+# CHECK: DWARFASTParserClang::ParseTypeFromDWARF{{.*}}DW_TAG_structure_type (DW_TAG_structure_type) name = 't2<t1>'
+# CHECK: DWARFASTParserClang::ParseTypeFromDWARF{{.*}}DW_TAG_structure_type (DW_TAG_structure_type) name = 't1'
+# CHECK: DW_TAG_structure_type (DW_TAG_structure_type) 't2<t1>' resolving forward declaration...
+# CHECK: (t2<t1>)  {}
+# CHECK: (lldb) p v2
+# CHECK: DWARFASTParserClang::ParseTypeFromDWARF{{.*}}DW_TAG_structure_type (DW_TAG_structure_type) name = 't1'
+# CHECK: DW_TAG_structure_type (DW_TAG_structure_type) 't1' resolving forward declaration...
+
+#--- lldb.cmd
+log enable dwarf comp
+p v1
+p v2
+
+#--- main.cpp
+template<typename T>
+struct t2 {
+};
+struct t1;
+t2<t1> v1; // this CU doesn't have definition DIE for t1, but only declaration DIE for it.
+int main() {
+}
+
+#--- t1_def.cpp
+struct t1 { // this CU contains definition DIE for t1.
+  int x;
+};
+t1 v2;