[Lldb-commits] [lldb] [lldb][DWARF] Fix adding children to clang type that hasn't started definition. (PR #93839)

[Zequan Wu via lldb-commits]

https://github.com/ZequanWu created https://github.com/llvm/llvm-project/pull/93839

This fixes https://github.com/llvm/llvm-project/pull/92328#issuecomment-2139339444.

This contains two fixes:
1. Do not differentiate `DW_TAG_class_type` and `DW_TAG_structure_type` in `UniqueDWARFASTTypeList`, because it's possible that DIE for a type is `DW_TAG_class_type` in one CU but is `DW_TAG_structure_type` in a different CU.
2. In case of we failed to find existing clang type (created from declaration) in `UniqueDWARFASTTypeMap` for some other reasons, start clang type definition in `DWARFASTParserClang::CompleteRecordType` to ensure we always started its definition before adding children. This should work because we know the DIE passing in `DWARFASTParserClang::CompleteRecordType` is always a definition DIE. 


>From 90cbcf8a97fb2e7c5131ac2cb601b95fe7a331c6 Mon Sep 17 00:00:00 2001
From: Zequan Wu <zequanwu at google.com>
Date: Thu, 30 May 2024 11:36:10 -0400
Subject: [PATCH] [lldb][DWARF] Do not differentiate DW_TAG_class_type and
 DW_TAG_struct_type in UniqueDWARFASTTypeList.

---
 .../Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp |  5 +++++
 .../Plugins/SymbolFile/DWARF/UniqueDWARFASTType.cpp  | 12 ++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
index e0b1b430b266f..78969d4752f80 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFASTParserClang.cpp
@@ -2232,6 +2232,11 @@ bool DWARFASTParserClang::CompleteRecordType(const DWARFDIE &die,
       // For objective C we don't start the definition when the class is
       // created.
       TypeSystemClang::StartTagDeclarationDefinition(clang_type);
+    } else if (!clang_type.IsBeingDefined()) {
+      // In case of some weired DWARF causing we don't start definition on this
+      // definition DIE because we failed to find existing clang_type from
+      // UniqueDWARFASTTypeMap due to overstrict checking.
+      TypeSystemClang::StartTagDeclarationDefinition(clang_type);
     }
 
     AccessType default_accessibility = eAccessNone;
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/UniqueDWARFASTType.cpp b/lldb/source/Plugins/SymbolFile/DWARF/UniqueDWARFASTType.cpp
index 4762356034cab..3d201e96f92c3 100644
--- a/lldb/source/Plugins/SymbolFile/DWARF/UniqueDWARFASTType.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/UniqueDWARFASTType.cpp
@@ -13,12 +13,18 @@
 using namespace lldb_private::dwarf;
 using namespace lldb_private::plugin::dwarf;
 
+static bool IsStructOrClassTag(llvm::dwarf::Tag Tag) {
+  return Tag == llvm::dwarf::Tag::DW_TAG_class_type ||
+         Tag == llvm::dwarf::Tag::DW_TAG_structure_type;
+}
+
 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()) {
+    if (udt.m_die.Tag() == die.Tag() || (IsStructOrClassTag(udt.m_die.Tag()) &&
+                                         IsStructOrClassTag(die.Tag()))) {
       // 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.
@@ -39,7 +45,9 @@ UniqueDWARFASTType *UniqueDWARFASTTypeList::Find(
       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) {
+        if (parent_arg_tag == parent_pos_tag ||
+            (IsStructOrClassTag(parent_arg_tag) &&
+             IsStructOrClassTag(parent_pos_tag))) {
           switch (parent_arg_tag) {
           case DW_TAG_class_type:
           case DW_TAG_structure_type: