[lldb] Move DWARFDeclContext functions from DWARFDebugInfoEntry to DW… (#95227)

…ARFDIE

This puts them closer to the other two functions doing something very
similar. I've tried to stick to the original logic of the functions as
much as possible, though I did apply some easy simplifications.

The changes in DWARFDeclContext.h are there to make the unit tests
produce more useful error messages.

Author: labath

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

@@ -2461,7 +2461,7 @@ DWARFASTParserClang::ConstructDemangledNameFromDWARF(const DWARFDIE &die) {
   std::vector<clang::ParmVarDecl *> param_decls;
   StreamString sstr;
 
-  DWARFDeclContext decl_ctx = SymbolFileDWARF::GetDWARFDeclContext(die);
+  DWARFDeclContext decl_ctx = die.GetDWARFDeclContext();
   sstr << decl_ctx.GetQualifiedName();
 
   clang::DeclContext *containing_decl_ctx =

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

@@ -505,12 +505,64 @@ std::vector<CompilerContext> DWARFDIE::GetTypeLookupContext() const {
   return context;
 }
 
+static DWARFDeclContext GetDWARFDeclContextImpl(DWARFDIE die) {
+  DWARFDeclContext dwarf_decl_ctx;
+  while (die) {
+    const dw_tag_t tag = die.Tag();
+    if (tag == DW_TAG_compile_unit || tag == DW_TAG_partial_unit)
+      break;
+    dwarf_decl_ctx.AppendDeclContext(tag, die.GetName());
+    DWARFDIE parent_decl_ctx_die = die.GetParentDeclContextDIE();
+    if (parent_decl_ctx_die == die)
+      break;
+    die = parent_decl_ctx_die;
+  }
+  return dwarf_decl_ctx;
+}
+
+DWARFDeclContext DWARFDIE::GetDWARFDeclContext() const {
+  return GetDWARFDeclContextImpl(*this);
+}
+
+static DWARFDIE GetParentDeclContextDIEImpl(DWARFDIE die) {
+  DWARFDIE orig_die = die;
+  while (die) {
+    // If this is the original DIE that we are searching for a declaration for,
+    // then don't look in the cache as we don't want our own decl context to be
+    // our decl context...
+    if (die != orig_die) {
+      switch (die.Tag()) {
+      case DW_TAG_compile_unit:
+      case DW_TAG_partial_unit:
+      case DW_TAG_namespace:
+      case DW_TAG_structure_type:
+      case DW_TAG_union_type:
+      case DW_TAG_class_type:
+        return die;
+
+      default:
+        break;
+      }
+    }
+
+    if (DWARFDIE spec_die = die.GetReferencedDIE(DW_AT_specification)) {
+      if (DWARFDIE decl_ctx_die = spec_die.GetParentDeclContextDIE())
+        return decl_ctx_die;
+    }
+
+    if (DWARFDIE abs_die = die.GetReferencedDIE(DW_AT_abstract_origin)) {
+      if (DWARFDIE decl_ctx_die = abs_die.GetParentDeclContextDIE())
+        return decl_ctx_die;
+    }
+
+    die = die.GetParent();
+  }
+  return DWARFDIE();
+}
+
 DWARFDIE
 DWARFDIE::GetParentDeclContextDIE() const {
-  if (IsValid())
-    return m_die->GetParentDeclContextDIE(m_cu);
-  else
-    return DWARFDIE();
+  return GetParentDeclContextDIEImpl(*this);
 }
 
 bool DWARFDIE::IsStructUnionOrClass() const {

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

@@ -86,6 +86,8 @@ class DWARFDIE : public DWARFBaseDIE {
   /// using a full or partial CompilerContext array.
   std::vector<CompilerContext> GetTypeLookupContext() const;
 
+  DWARFDeclContext GetDWARFDeclContext() const;
+
   // Getting attribute values from the DIE.
   //
   // GetAttributeValueAsXXX() functions should only be used if you are

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

@@ -610,79 +610,6 @@ void DWARFDebugInfoEntry::BuildFunctionAddressRangeTable(
   }
 }
 
-DWARFDeclContext
-DWARFDebugInfoEntry::GetDWARFDeclContextStatic(const DWARFDebugInfoEntry *die,
-                                               DWARFUnit *cu) {
-  DWARFDeclContext dwarf_decl_ctx;
-  for (;;) {
-    const dw_tag_t tag = die->Tag();
-    if (tag == DW_TAG_compile_unit || tag == DW_TAG_partial_unit)
-      return dwarf_decl_ctx;
-    dwarf_decl_ctx.AppendDeclContext(tag, die->GetName(cu));
-    DWARFDIE parent_decl_ctx_die = die->GetParentDeclContextDIE(cu);
-    if (!parent_decl_ctx_die || parent_decl_ctx_die.GetDIE() == die)
-      return dwarf_decl_ctx;
-    if (parent_decl_ctx_die.Tag() == DW_TAG_compile_unit ||
-        parent_decl_ctx_die.Tag() == DW_TAG_partial_unit)
-      return dwarf_decl_ctx;
-    die = parent_decl_ctx_die.GetDIE();
-    cu = parent_decl_ctx_die.GetCU();
-  }
-}
-
-DWARFDeclContext DWARFDebugInfoEntry::GetDWARFDeclContext(DWARFUnit *cu) const {
-  return GetDWARFDeclContextStatic(this, cu);
-}
-
-DWARFDIE
-DWARFDebugInfoEntry::GetParentDeclContextDIE(DWARFUnit *cu) const {
-  DWARFAttributes attributes = GetAttributes(cu, Recurse::yes);
-  return GetParentDeclContextDIE(cu, attributes);
-}
-
-DWARFDIE
-DWARFDebugInfoEntry::GetParentDeclContextDIE(
-    DWARFUnit *cu, const DWARFAttributes &attributes) const {
-  DWARFDIE die(cu, const_cast<DWARFDebugInfoEntry *>(this));
-
-  while (die) {
-    // If this is the original DIE that we are searching for a declaration for,
-    // then don't look in the cache as we don't want our own decl context to be
-    // our decl context...
-    if (die.GetDIE() != this) {
-      switch (die.Tag()) {
-      case DW_TAG_compile_unit:
-      case DW_TAG_partial_unit:
-      case DW_TAG_namespace:
-      case DW_TAG_structure_type:
-      case DW_TAG_union_type:
-      case DW_TAG_class_type:
-        return die;
-
-      default:
-        break;
-      }
-    }
-
-    DWARFDIE spec_die = attributes.FormValueAsReference(DW_AT_specification);
-    if (spec_die) {
-      DWARFDIE decl_ctx_die = spec_die.GetParentDeclContextDIE();
-      if (decl_ctx_die)
-        return decl_ctx_die;
-    }
-
-    DWARFDIE abs_die = attributes.FormValueAsReference(DW_AT_abstract_origin);
-    if (abs_die) {
-      DWARFDIE decl_ctx_die = abs_die.GetParentDeclContextDIE();
-      if (decl_ctx_die)
-        return decl_ctx_die;
-    }
-
-    die = die.GetParent();
-  }
-  return DWARFDIE();
-}
-
 lldb::offset_t DWARFDebugInfoEntry::GetFirstAttributeOffset() const {
   return GetOffset() + llvm::getULEB128Size(m_abbr_idx);
 }

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

@@ -157,12 +157,6 @@ class DWARFDebugInfoEntry {
     return HasChildren() ? this + 1 : nullptr;
   }
 
-  DWARFDeclContext GetDWARFDeclContext(DWARFUnit *cu) const;
-
-  DWARFDIE GetParentDeclContextDIE(DWARFUnit *cu) const;
-  DWARFDIE GetParentDeclContextDIE(DWARFUnit *cu,
-                                   const DWARFAttributes &attributes) const;
-
   void SetSiblingIndex(uint32_t idx) { m_sibling_idx = idx; }
   void SetParentIndex(uint32_t idx) { m_parent_idx = idx; }
 
@@ -172,9 +166,6 @@ class DWARFDebugInfoEntry {
   bool IsGlobalOrStaticScopeVariable() const;
 
 protected:
-  static DWARFDeclContext
-  GetDWARFDeclContextStatic(const DWARFDebugInfoEntry *die, DWARFUnit *cu);
-
   // Up to 2TB offset within the .debug_info/.debug_types
   dw_offset_t m_offset : DW_DIE_OFFSET_MAX_BITSIZE;
   // How many to subtract from "this" to get the parent. If zero this die has no

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

@@ -12,18 +12,16 @@
 using namespace lldb_private::dwarf;
 using namespace lldb_private::plugin::dwarf;
 
-/// Returns the name of `entry` if it has one, or the appropriate "anonymous
-/// {namespace, class, struct, union}".
-static const char *GetName(DWARFDeclContext::Entry entry) {
-  if (entry.name != nullptr)
-    return entry.name;
-  if (entry.tag == DW_TAG_namespace)
+const char *DWARFDeclContext::Entry::GetName() const {
+  if (name != nullptr)
+    return name;
+  if (tag == DW_TAG_namespace)
     return "(anonymous namespace)";
-  if (entry.tag == DW_TAG_class_type)
+  if (tag == DW_TAG_class_type)
     return "(anonymous class)";
-  if (entry.tag == DW_TAG_structure_type)
+  if (tag == DW_TAG_structure_type)
     return "(anonymous struct)";
-  if (entry.tag == DW_TAG_union_type)
+  if (tag == DW_TAG_union_type)
     return "(anonymous union)";
   return "(anonymous)";
 }
@@ -46,7 +44,7 @@ const char *DWARFDeclContext::GetQualifiedName() const {
         llvm::raw_string_ostream string_stream(m_qualified_name);
         llvm::interleave(
             llvm::reverse(m_entries), string_stream,
-            [&](auto entry) { string_stream << GetName(entry); }, "::");
+            [&](auto entry) { string_stream << entry.GetName(); }, "::");
       }
     }
   }

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

@@ -9,8 +9,9 @@
 #ifndef LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_DWARFDECLCONTEXT_H
 #define LLDB_SOURCE_PLUGINS_SYMBOLFILE_DWARF_DWARFDECLCONTEXT_H
 
-#include "lldb/Utility/ConstString.h"
 #include "DWARFDefines.h"
+#include "lldb/Utility/ConstString.h"
+#include "llvm/ADT/StringExtras.h"
 
 #include <cassert>
 #include <string>
@@ -38,6 +39,10 @@ class DWARFDeclContext {
       return false;
     }
 
+    /// Returns the name of this entry if it has one, or the appropriate
+    /// "anonymous {namespace, class, struct, union}".
+    const char *GetName() const;
+
     // Test operator
     explicit operator bool() const { return tag != 0; }
 
@@ -83,6 +88,17 @@ class DWARFDeclContext {
     m_qualified_name.clear();
   }
 
+  friend llvm::raw_ostream &operator<<(llvm::raw_ostream &OS,
+                                       const DWARFDeclContext &ctx) {
+    OS << "DWARFDeclContext{";
+    llvm::ListSeparator LS;
+    for (const Entry &e : ctx.m_entries) {
+      OS << LS << "{" << DW_TAG_value_to_name(e.tag) << ", " << e.GetName()
+         << "}";
+    }
+    return OS << "}";
+  }
+
 protected:
   typedef std::vector<Entry> collection;
   collection m_entries;

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

@@ -121,8 +121,7 @@ void DWARFIndex::GetFullyQualifiedType(
 bool DWARFIndex::GetFullyQualifiedTypeImpl(
     const DWARFDeclContext &context, DWARFDIE die,
     llvm::function_ref<bool(DWARFDIE die)> callback) {
-  DWARFDeclContext dwarf_decl_ctx =
-      die.GetDIE()->GetDWARFDeclContext(die.GetCU());
+  DWARFDeclContext dwarf_decl_ctx = die.GetDWARFDeclContext();
   if (dwarf_decl_ctx == context)
     return callback(die);
   return true;

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

@@ -3080,7 +3080,7 @@ SymbolFileDWARF::FindDefinitionTypeForDWARFDeclContext(const DWARFDIE &die) {
         template_params = dwarf_ast->GetDIEClassTemplateParams(die);
     }
 
-    const DWARFDeclContext die_dwarf_decl_ctx = GetDWARFDeclContext(die);
+    const DWARFDeclContext die_dwarf_decl_ctx = die.GetDWARFDeclContext();
     m_index->GetFullyQualifiedType(die_dwarf_decl_ctx, [&](DWARFDIE type_die) {
       // Make sure type_die's language matches the type system we are
       // looking for. We don't want to find a "Foo" type from Java if we
@@ -3109,7 +3109,7 @@ SymbolFileDWARF::FindDefinitionTypeForDWARFDeclContext(const DWARFDIE &die) {
       }
 
       if (log) {
-        DWARFDeclContext type_dwarf_decl_ctx = GetDWARFDeclContext(type_die);
+        DWARFDeclContext type_dwarf_decl_ctx = type_die.GetDWARFDeclContext();
         GetObjectFile()->GetModule()->LogMessage(
             log,
             "SymbolFileDWARF::"
@@ -3535,8 +3535,9 @@ VariableSP SymbolFileDWARF::ParseVariableDIE(const SymbolContext &sc,
     if ((parent_tag == DW_TAG_compile_unit ||
          parent_tag == DW_TAG_partial_unit) &&
         Language::LanguageIsCPlusPlus(GetLanguage(*die.GetCU())))
-      mangled =
-          GetDWARFDeclContext(die).GetQualifiedNameAsConstString().GetCString();
+      mangled = die.GetDWARFDeclContext()
+                    .GetQualifiedNameAsConstString()
+                    .GetCString();
   }
 
   if (tag == DW_TAG_formal_parameter)
@@ -4361,14 +4362,6 @@ SymbolFileDWARF::GetContainingDeclContext(const DWARFDIE &die) {
   return CompilerDeclContext();
 }
 
-DWARFDeclContext SymbolFileDWARF::GetDWARFDeclContext(const DWARFDIE &die) {
-  if (!die.IsValid())
-    return {};
-  DWARFDeclContext dwarf_decl_ctx =
-      die.GetDIE()->GetDWARFDeclContext(die.GetCU());
-  return dwarf_decl_ctx;
-}
-
 LanguageType SymbolFileDWARF::LanguageTypeFromDWARF(uint64_t val) {
   // Note: user languages between lo_user and hi_user must be handled
   // explicitly here.

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

@@ -296,8 +296,6 @@ class SymbolFileDWARF : public SymbolFileCommon {
 
   static CompilerDeclContext GetContainingDeclContext(const DWARFDIE &die);
 
-  static DWARFDeclContext GetDWARFDeclContext(const DWARFDIE &die);
-
   static lldb::LanguageType LanguageTypeFromDWARF(uint64_t val);
 
   static lldb::LanguageType GetLanguage(DWARFUnit &unit);

lldb/unittests/SymbolFile/DWARF/DWARFDIETest.cpp

@@ -8,6 +8,7 @@
 
 #include "Plugins/SymbolFile/DWARF/DWARFDIE.h"
 #include "Plugins/SymbolFile/DWARF/DWARFDebugInfo.h"
+#include "Plugins/SymbolFile/DWARF/DWARFDeclContext.h"
 #include "TestingSupport/Symbol/YAMLModuleTester.h"
 #include "lldb/Core/dwarf.h"
 #include "lldb/Symbol/Type.h"
@@ -19,6 +20,7 @@
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::plugin::dwarf;
+using namespace lldb_private::dwarf;
 
 TEST(DWARFDIETest, ChildIteration) {
   // Tests DWARFDIE::child_iterator.
@@ -257,6 +259,9 @@ TEST(DWARFDIETest, GetContext) {
   EXPECT_THAT(
       struct_die.GetTypeLookupContext(),
       testing::ElementsAre(make_namespace("NAMESPACE"), make_struct("STRUCT")));
+  EXPECT_THAT(struct_die.GetDWARFDeclContext(),
+              DWARFDeclContext({{DW_TAG_structure_type, "STRUCT"},
+                                {DW_TAG_namespace, "NAMESPACE"}}));
 }
 
 TEST(DWARFDIETest, GetContextInFunction) {