[lldb][dwarf] Compute fully qualified names on simplified template names with DWARFTypePrinter (#112811)

This is the second half of
#90008.

Essentially, it replaces the work of resolving template types when we
just need the qualified names with walking the DIE tree using
`DWARFTypePrinter`.

### Result
For an internal target, the time spent on `expr *this` for the first
time reduced from 28 secs to 17 secs.

Author: ZequanWu

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

@@ -45,6 +45,7 @@
 #include "clang/AST/Type.h"
 #include "clang/Basic/Specifiers.h"
 #include "llvm/ADT/StringExtras.h"
+#include "llvm/DebugInfo/DWARF/DWARFTypePrinter.h"
 #include "llvm/Demangle/Demangle.h"
 
 #include <map>
@@ -826,11 +827,11 @@ std::string DWARFASTParserClang::GetDIEClassTemplateParams(DWARFDIE die) {
   if (llvm::StringRef(die.GetName()).contains("<"))
     return {};
 
-  TypeSystemClang::TemplateParameterInfos template_param_infos;
-  if (ParseTemplateParameterInfos(die, template_param_infos))
-    return m_ast.PrintTemplateParams(template_param_infos);
-
-  return {};
+  std::string name;
+  llvm::raw_string_ostream os(name);
+  llvm::DWARFTypePrinter<DWARFDIE> type_printer(os);
+  type_printer.appendAndTerminateTemplateParameters(die);
+  return name;
 }
 
 void DWARFASTParserClang::MapDeclDIEToDefDIE(
@@ -1618,9 +1619,9 @@ void DWARFASTParserClang::GetUniqueTypeNameAndDeclaration(
     case DW_TAG_structure_type:
     case DW_TAG_union_type: {
       if (const char *class_union_struct_name = parent_decl_ctx_die.GetName()) {
-        qualified_name.insert(
-            0, GetDIEClassTemplateParams(parent_decl_ctx_die));
         qualified_name.insert(0, "::");
+        qualified_name.insert(0,
+                              GetDIEClassTemplateParams(parent_decl_ctx_die));
         qualified_name.insert(0, class_union_struct_name);
       }
       parent_decl_ctx_die = parent_decl_ctx_die.GetParentDeclContextDIE();
@@ -1673,6 +1674,12 @@ DWARFASTParserClang::ParseStructureLikeDIE(const SymbolContext &sc,
   if (attrs.name) {
     GetUniqueTypeNameAndDeclaration(die, cu_language, unique_typename,
                                     unique_decl);
+    if (log) {
+      dwarf->GetObjectFile()->GetModule()->LogMessage(
+          log, "SymbolFileDWARF({0:p}) - {1:x16}: {2} has unique name: {3} ",
+          static_cast<void *>(this), die.GetID(), DW_TAG_value_to_name(tag),
+          unique_typename.AsCString());
+    }
     if (UniqueDWARFASTType *unique_ast_entry_type =
             dwarf->GetUniqueDWARFASTTypeMap().Find(
                 unique_typename, die, unique_decl, byte_size,

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

@@ -24,9 +24,11 @@ class DWARFUnit;
 class DWARFDebugInfoEntry;
 class DWARFDeclContext;
 class SymbolFileDWARF;
+class DWARFFormValue;
 
 class DWARFBaseDIE {
 public:
+  using DWARFFormValue = dwarf::DWARFFormValue;
   DWARFBaseDIE() = default;
 
   DWARFBaseDIE(DWARFUnit *cu, DWARFDebugInfoEntry *die)
@@ -117,6 +119,12 @@ class DWARFBaseDIE {
   enum class Recurse : bool { no, yes };
   DWARFAttributes GetAttributes(Recurse recurse = Recurse::yes) const;
 
+  // The following methods use LLVM naming convension in order to be are used by
+  // LLVM libraries.
+  dw_tag_t getTag() const { return Tag(); }
+
+  const char *getShortName() const { return GetName(); }
+
 protected:
   DWARFUnit *m_cu = nullptr;
   DWARFDebugInfoEntry *m_die = nullptr;

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

@@ -572,6 +572,43 @@ bool DWARFDIE::GetDIENamesAndRanges(
     return false;
 }
 
+// The following methods use LLVM naming convension in order to be are used by
+// LLVM libraries.
 llvm::iterator_range<DWARFDIE::child_iterator> DWARFDIE::children() const {
   return llvm::make_range(child_iterator(*this), child_iterator());
 }
+
+DWARFDIE::child_iterator DWARFDIE::begin() const {
+  return child_iterator(*this);
+}
+
+DWARFDIE::child_iterator DWARFDIE::end() const { return child_iterator(); }
+
+std::optional<DWARFFormValue> DWARFDIE::find(const dw_attr_t attr) const {
+  DWARFFormValue form_value;
+  if (m_die->GetAttributeValue(m_cu, attr, form_value, nullptr, false))
+    return form_value;
+  return std::nullopt;
+}
+
+std::optional<uint64_t> DWARFDIE::getLanguage() const {
+  if (IsValid())
+    return m_cu->GetDWARFLanguageType();
+  return std::nullopt;
+}
+
+DWARFDIE DWARFDIE::resolveReferencedType(dw_attr_t attr) const {
+  return GetReferencedDIE(attr);
+}
+
+DWARFDIE DWARFDIE::resolveReferencedType(DWARFFormValue v) const {
+  if (IsValid())
+    return v.Reference();
+  return {};
+}
+
+DWARFDIE DWARFDIE::resolveTypeUnitReference() const {
+  if (DWARFDIE reference = GetReferencedDIE(DW_AT_signature))
+    return reference;
+  return *this;
+}

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

@@ -103,8 +103,25 @@ class DWARFDIE : public DWARFBaseDIE {
       std::optional<int> &call_line, std::optional<int> &call_column,
       DWARFExpressionList *frame_base) const;
 
+  // The following methods use LLVM naming convension in order to be are used by
+  // LLVM libraries.
+  std::optional<uint64_t> getLanguage() const;
+
+  DWARFDIE getParent() const { return GetParent(); }
+
+  DWARFDIE resolveReferencedType(dw_attr_t attr) const;
+
+  DWARFDIE resolveReferencedType(DWARFFormValue v) const;
+
+  DWARFDIE resolveTypeUnitReference() const;
+
+  std::optional<DWARFFormValue> find(const dw_attr_t attr) const;
+
   /// The range of all the children of this DIE.
   llvm::iterator_range<child_iterator> children() const;
+
+  child_iterator begin() const;
+  child_iterator end() const;
 };
 
 class DWARFDIE::child_iterator

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

@@ -574,6 +574,31 @@ uint64_t DWARFFormValue::Reference(dw_offset_t base_offset) const {
   }
 }
 
+std::optional<uint64_t> DWARFFormValue::getAsUnsignedConstant() const {
+  if ((!IsDataForm(m_form)) || m_form == lldb_private::dwarf::DW_FORM_sdata)
+    return std::nullopt;
+  return m_value.uval;
+}
+
+std::optional<int64_t> DWARFFormValue::getAsSignedConstant() const {
+  if ((!IsDataForm(m_form)) ||
+      (m_form == lldb_private::dwarf::DW_FORM_udata &&
+       uint64_t(std::numeric_limits<int64_t>::max()) < m_value.uval))
+    return std::nullopt;
+  switch (m_form) {
+  case lldb_private::dwarf::DW_FORM_data4:
+    return int32_t(m_value.uval);
+  case lldb_private::dwarf::DW_FORM_data2:
+    return int16_t(m_value.uval);
+  case lldb_private::dwarf::DW_FORM_data1:
+    return int8_t(m_value.uval);
+  case lldb_private::dwarf::DW_FORM_sdata:
+  case lldb_private::dwarf::DW_FORM_data8:
+  default:
+    return m_value.sval;
+  }
+}
+
 const uint8_t *DWARFFormValue::BlockData() const { return m_value.data; }
 
 bool DWARFFormValue::IsBlockForm(const dw_form_t form) {

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

@@ -76,6 +76,12 @@ class DWARFFormValue {
   void Clear();
   static bool FormIsSupported(dw_form_t form);
 
+  // The following methods use LLVM naming convension in order to be are used by
+  // LLVM libraries.
+  std::optional<uint64_t> getAsUnsignedConstant() const;
+  std::optional<int64_t> getAsSignedConstant() const;
+  const char *getAsCString() const { return AsCString(); }
+
 protected:
   // Compile unit where m_value was located.
   // It may be different from compile unit where m_value refers to.

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

@@ -9,6 +9,7 @@
 #include "SymbolFileDWARF.h"
 
 #include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
+#include "llvm/DebugInfo/DWARF/DWARFTypePrinter.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/FileUtilities.h"
 #include "llvm/Support/Format.h"
@@ -2810,33 +2811,14 @@ void SymbolFileDWARF::FindTypes(const TypeQuery &query, TypeResults &results) {
             return true; // Keep iterating over index types, language mismatch.
         }
 
-        // Check the context matches
-        std::vector<lldb_private::CompilerContext> die_context;
-        if (query.GetModuleSearch())
-          die_context = die.GetDeclContext();
-        else
-          die_context = die.GetTypeLookupContext();
-        assert(!die_context.empty());
-        if (!query_simple.ContextMatches(die_context))
-          return true; // Keep iterating over index types, context mismatch.
-
-        // Try to resolve the type.
-        if (Type *matching_type = ResolveType(die, true, true)) {
-          ConstString name = matching_type->GetQualifiedName();
-          // We have found a type that still might not match due to template
-          // parameters. If we create a new TypeQuery that uses the new type's
-          // fully qualified name, we can find out if this type matches at all
-          // context levels. We can't use just the "match_simple" context
-          // because all template parameters were stripped off. The fully
-          // qualified name of the type will have the template parameters and
-          // will allow us to make sure it matches correctly.
-          TypeQuery die_query(name.GetStringRef(),
-                              TypeQueryOptions::e_exact_match);
-          if (!query.ContextMatches(die_query.GetContextRef()))
-            return true; // Keep iterating over index types, context mismatch.
-
-          results.InsertUnique(matching_type->shared_from_this());
-        }
+        std::string qualified_name;
+        llvm::raw_string_ostream os(qualified_name);
+        llvm::DWARFTypePrinter<DWARFDIE> type_printer(os);
+        type_printer.appendQualifiedName(die);
+        TypeQuery die_query(qualified_name, e_exact_match);
+        if (query.ContextMatches(die_query.GetContextRef()))
+          if (Type *matching_type = ResolveType(die, true, true))
+            results.InsertUnique(matching_type->shared_from_this());
         return !results.Done(query); // Keep iterating if we aren't done.
       });
       if (results.Done(query)) {

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

@@ -1403,26 +1403,6 @@ static TemplateParameterList *CreateTemplateParameterList(
   return template_param_list;
 }
 
-std::string TypeSystemClang::PrintTemplateParams(
-    const TemplateParameterInfos &template_param_infos) {
-  llvm::SmallVector<NamedDecl *, 8> ignore;
-  clang::TemplateParameterList *template_param_list =
-      CreateTemplateParameterList(getASTContext(), template_param_infos,
-                                  ignore);
-  llvm::SmallVector<clang::TemplateArgument, 2> args(
-      template_param_infos.GetArgs());
-  if (template_param_infos.hasParameterPack()) {
-    llvm::ArrayRef<TemplateArgument> pack_args =
-        template_param_infos.GetParameterPackArgs();
-    args.append(pack_args.begin(), pack_args.end());
-  }
-  std::string str;
-  llvm::raw_string_ostream os(str);
-  clang::printTemplateArgumentList(os, args, GetTypePrintingPolicy(),
-                                   template_param_list);
-  return str;
-}
-
 clang::FunctionTemplateDecl *TypeSystemClang::CreateFunctionTemplateDecl(
     clang::DeclContext *decl_ctx, OptionalClangModuleID owning_module,
     clang::FunctionDecl *func_decl,

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.h

@@ -1148,10 +1148,6 @@ class TypeSystemClang : public TypeSystem {
 
   bool SetDeclIsForcefullyCompleted(const clang::TagDecl *td);
 
-  /// Return the template parameters (including surrounding <>) in string form.
-  std::string
-  PrintTemplateParams(const TemplateParameterInfos &template_param_infos);
-
 private:
   /// Returns the PrintingPolicy used when generating the internal type names.
   /// These type names are mostly used for the formatter selection.

lldb/test/Shell/SymbolFile/DWARF/x86/simplified-template-names.cpp

@@ -0,0 +1,36 @@
+// Test lldb is able to compute the fully qualified names on templates with
+// -gsimple-template-names and -fdebug-types-section.
+
+// REQUIRES: lld
+
+// Test against logging to see if we print the fully qualified names correctly.
+// RUN: %clangxx --target=x86_64-pc-linux -g -gsimple-template-names %s -o %t
+// RUN: %lldb %t -o "log enable dwarf comp" -o "target variable v3" -o exit | FileCheck %s --check-prefix=LOG
+
+// Test that we following DW_AT_signature correctly. If not, lldb might confuse the types of v1 and v2.
+// RUN: %clangxx --target=x86_64-pc-linux -g -gsimple-template-names -fdebug-types-section %s -o %t
+// RUN: %lldb %t -o "target variable v1 v2" -o exit | FileCheck %s --check-prefix=TYPE
+
+// LOG: unique name: t3<t2<int> >::t4
+
+// TYPE:      (t2<outer_struct1::t1<int> >) v1 = {}
+// TYPE-NEXT: (t2<outer_struct2::t1<int> >) v2 = {}
+
+struct outer_struct1 {
+  template <typename> struct t1 {};
+};
+
+struct outer_struct2 {
+  template <typename> struct t1 {};
+};
+
+template <typename> struct t2 {};
+t2<outer_struct1::t1<int>> v1;
+t2<outer_struct2::t1<int>> v2;
+
+template <typename> struct t3 {
+  struct t4 {};
+};
+t3<t2<int>>::t4 v3;
+
+int main() {}