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Construct namespace prefixes for unqualified DW_AT_name #319

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Merged
jeremy-rifkin merged 11 commits into from
Feb 28, 2026
Merged

Construct namespace prefixes for unqualified DW_AT_name #319

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223fbf1
Construct namespace prefixes for unqualified DW_AT_name
jeremy-rifkin Feb 27, 2026
31d91e1
Better handle namespace prefixes for inlined subroutines and abstract…
jeremy-rifkin Feb 27, 2026
9a7fd9e
Some cleanup and sipmlification
jeremy-rifkin Feb 27, 2026
cfdfdda
Add a test to hopefully cover the namespace resolution DW_AT_name cod…
jeremy-rifkin Feb 27, 2026
5f9d06c
Fix if defined(CPPTRACE_GET_SYMBOLS_WITH_LIBDWARF) check in tests
jeremy-rifkin Feb 28, 2026
a26f1e2
Fix and cleanup
jeremy-rifkin Feb 28, 2026
c5daead
Cleanup and explanation
jeremy-rifkin Feb 28, 2026
6b0ea6f
Cleanup
jeremy-rifkin Feb 28, 2026
80642c3
Cleanup
jeremy-rifkin Feb 28, 2026
cf48ecd
Cleanup
jeremy-rifkin Feb 28, 2026
83b0bf6
Cleanup
jeremy-rifkin Feb 28, 2026
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172 changes: 146 additions & 26 deletions src/symbols/dwarf/dwarf_resolver.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@
#include <string>
#include <type_traits>
#include <unordered_map>
#include <unordered_set>
#include <vector>

// It's been tricky to piece together how to handle all this dwarf stuff. Some resources I've used are
Expand Down Expand Up @@ -65,9 +66,14 @@ namespace libdwarf {
Dwarf_Signed arange_count = 0;
// Map from CU -> Line context
lru_cache<Dwarf_Off, line_table_info> line_tables{get_dwarf_resolver_line_table_cache_size()};
// string pool for namespace prefixes
std::unordered_set<std::string> prefix_pool;
// Map from CU -> Sorted subprograms vector
using subprogram_map = range_map<Dwarf_Addr, die_object>;
std::unordered_map<Dwarf_Off, subprogram_map> subprograms_cache;
// Map from subprogram die offset -> namespace prefix - best to have this separate from the subprogram cache
// since we may have entries here that don't have ranges
std::unordered_map<Dwarf_Off, string_view> namespace_prefix_cache;
// Vector of ranges and their corresponding CU offsets
struct compile_unit {
die_object die;
Expand Down Expand Up @@ -291,28 +297,99 @@ namespace libdwarf {
}
}

bool find_die_namespace_prefix(
const die_object& parent_die,
Dwarf_Off target_offset,
std::string& prefix
) {
auto child = parent_die.get_child();
if(!child) {
return false;
}
bool found = false;
walk_die_list(
child,
[this, target_offset, &prefix, &found] (const die_object& die) {
if(die.get_global_offset() == target_offset) {
found = true;
return false;
}
auto tag = die.get_tag();
bool contributes_prefix = tag == DW_TAG_namespace
|| tag == DW_TAG_class_type
|| tag == DW_TAG_structure_type;
if(
contributes_prefix
|| tag == DW_TAG_module
|| tag == DW_TAG_imported_module
|| tag == DW_TAG_compile_unit
|| tag == DW_TAG_subprogram
|| tag == DW_TAG_lexical_block
|| tag == DW_TAG_inlined_subroutine
) {
auto old_size = prefix.size();
if(contributes_prefix) {
auto name = die.get_string_attribute(DW_AT_name);
if(name) {
prefix += name.unwrap();
prefix += "::";
}
}
if(find_die_namespace_prefix(die, target_offset, prefix)) {
found = true;
return false;
}
prefix.resize(old_size);
}
return true;
}
);
return found;
}

std::string get_die_namespace_prefix(const die_object& cu_die, const die_object& target_die) {
// It's possible we get here even when we otherwise would have had a walked_prefix thanks to
// DW_AT_specification and DW_AT_abstract_origin
auto it = namespace_prefix_cache.find(target_die.get_global_offset());
if(it != namespace_prefix_cache.end()) {
return std::string(it->second);
}
std::string prefix;
find_die_namespace_prefix(cu_die, target_die.get_global_offset(), prefix);
return prefix;
}

std::string subprogram_symbol(
const die_object& cu_die,
const die_object& die,
Dwarf_Half dwversion
Dwarf_Half dwversion,
optional<string_view> walked_prefix = nullopt
) {
ASSERT(die.get_tag() == DW_TAG_subprogram || die.get_tag() == DW_TAG_inlined_subroutine);
optional<std::string> name;
if(auto linkage_name = die.get_string_attribute(DW_AT_linkage_name)) {
name = std::move(linkage_name);
} else if(auto linkage_name = die.get_string_attribute(DW_AT_MIPS_linkage_name)) {
name = std::move(linkage_name);
} else if(auto linkage_name = die.get_string_attribute(DW_AT_name)) {
name = std::move(linkage_name);
} else if(auto raw_name = die.get_string_attribute(DW_AT_name)) {
// DW_AT_name is unqualified according to the DWARF standard
// In cache_mode == speed we preprocess all the namespace prefixes and a cache will hit in
// get_die_namespace_prefix, otherwise hopefully we can use the prefix we collected while walking
// and otherwise we'll have to re-walk from the cu_die to create the namespace prefix
auto prefix = walked_prefix.has_value()
? std::string(walked_prefix.unwrap())
: get_die_namespace_prefix(cu_die, die);
name = prefix + raw_name.unwrap();
}
if(name.has_value()) {
return std::move(name).unwrap();
} else {
if(die.has_attr(DW_AT_specification)) {
die_object spec = die.resolve_reference_attribute(DW_AT_specification);
return subprogram_symbol(spec, dwversion);
return subprogram_symbol(cu_die, spec, dwversion);
} else if(die.has_attr(DW_AT_abstract_origin)) {
die_object spec = die.resolve_reference_attribute(DW_AT_abstract_origin);
return subprogram_symbol(spec, dwversion);
return subprogram_symbol(cu_die, spec, dwversion);
}
}
return "";
Expand Down Expand Up @@ -375,7 +452,7 @@ namespace libdwarf {
child,
[this, &cu_die, pc, dwversion, &inlines, &target_die, &current_obj_holder] (const die_object& die) {
if(die.get_tag() == DW_TAG_inlined_subroutine && die.pc_in_die(cu_die, dwversion, pc)) {
const auto name = subprogram_symbol(die, dwversion);
const auto name = subprogram_symbol(cu_die, die, dwversion);
auto file_i = die.get_unsigned_attribute(DW_AT_call_file);
// TODO: Refactor.... Probably put logic in resolve_filename.
if(file_i) {
Expand Down Expand Up @@ -437,10 +514,11 @@ namespace libdwarf {
const die_object& die,
Dwarf_Addr pc,
Dwarf_Half dwversion,
std::vector<stacktrace_frame>& inlines
std::vector<stacktrace_frame>& inlines,
optional<string_view> walked_prefix = nullopt
) {
ASSERT(die.get_tag() == DW_TAG_subprogram);
const auto name = subprogram_symbol(die, dwversion);
const auto name = subprogram_symbol(cu_die, die, dwversion, walked_prefix);
if(should_resolve_inlined_calls()) {
get_inlines_info(cu_die, die, pc, dwversion, inlines);
}
Expand All @@ -455,12 +533,13 @@ namespace libdwarf {
Dwarf_Addr pc,
Dwarf_Half dwversion,
stacktrace_frame& frame,
std::vector<stacktrace_frame>& inlines
std::vector<stacktrace_frame>& inlines,
std::string& prefix
) {
bool found = false;
walk_die_list(
die,
[this, &cu_die, pc, dwversion, &frame, &inlines, &found] (const die_object& die) {
[this, &cu_die, pc, dwversion, &frame, &inlines, &found, &prefix] (const die_object& die) {
if(dump_dwarf) {
std::fprintf(
stderr,
Expand All @@ -485,13 +564,30 @@ namespace libdwarf {
);
}
if(die.get_tag() == DW_TAG_subprogram) {
frame.symbol = retrieve_symbol_for_subprogram(cu_die, die, pc, dwversion, inlines);
frame.symbol = retrieve_symbol_for_subprogram(cu_die, die, pc, dwversion, inlines, prefix);
found = true;
return false;
}
auto child = die.get_child();
if(child) {
if(retrieve_symbol_walk(cu_die, child, pc, dwversion, frame, inlines)) {
auto old_size = prefix.size();
auto tag = die.get_tag();
if(
tag == DW_TAG_namespace
|| tag == DW_TAG_class_type
|| tag == DW_TAG_structure_type
) {
auto name = die.get_string_attribute(DW_AT_name);
if(name) {
prefix += name.unwrap();
prefix += "::";
}
}
bool child_found = retrieve_symbol_walk(
cu_die, child, pc, dwversion, frame, inlines, prefix
);
prefix.resize(old_size);
if(child_found) {
found = true;
return false;
}
Expand All @@ -515,41 +611,63 @@ namespace libdwarf {
const die_object& cu_die,
const die_object& die,
Dwarf_Half dwversion,
subprogram_map& subprogram_cache
subprogram_map& subprogram_cache,
std::string& prefix
) {
walk_die_list(
die,
[this, &cu_die, dwversion, &subprogram_cache] (const die_object& die) {
[this, &cu_die, dwversion, &subprogram_cache, &prefix] (const die_object& die) {
switch(die.get_tag()) {
case DW_TAG_subprogram:
case DW_TAG_inlined_subroutine:
{
auto ranges_vec = die.get_rangelist_entries(cu_die, dwversion);
// TODO: Feels super inefficient and some day should maybe use an interval tree.
if(!ranges_vec.empty()) {
auto die_handle = subprogram_cache.add_item(die.clone());
for(auto range : ranges_vec) {
subprogram_cache.insert(die_handle, range.first, range.second);
const auto& interned = *prefix_pool.insert(prefix).first;
namespace_prefix_cache.emplace(die.get_global_offset(), interned);
if(die.get_tag() == DW_TAG_subprogram) {
auto ranges_vec = die.get_rangelist_entries(cu_die, dwversion);
// TODO: Feels super inefficient and some day should maybe use an interval
// tree.
if(!ranges_vec.empty()) {
auto die_handle = subprogram_cache.add_item(die.clone());
for(auto range : ranges_vec) {
subprogram_cache.insert(die_handle, range.first, range.second);
}
}
}
// Walk children to get things like lambdas
// TODO: Somehow find a way to get better names here? For gcc it's just "operator()"
// On clang it's better
// TODO: Somehow find a way to get better names here? For gcc it's just
// "operator()". On clang it's better.
auto child = die.get_child();
if(child) {
preprocess_subprograms(cu_die, child, dwversion, subprogram_cache);
preprocess_subprograms(cu_die, child, dwversion, subprogram_cache, prefix);
}
}
break;
case DW_TAG_namespace:
case DW_TAG_structure_type:
case DW_TAG_class_type:
{
auto child = die.get_child();
if(child) {
auto old_size = prefix.size();
auto name = die.get_string_attribute(DW_AT_name);
if(name) {
prefix += name.unwrap();
prefix += "::";
}
preprocess_subprograms(cu_die, child, dwversion, subprogram_cache, prefix);
prefix.resize(old_size);
}
}
break;
case DW_TAG_lexical_block:
case DW_TAG_module:
case DW_TAG_imported_module:
case DW_TAG_compile_unit:
{
auto child = die.get_child();
if(child) {
preprocess_subprograms(cu_die, child, dwversion, subprogram_cache);
preprocess_subprograms(cu_die, child, dwversion, subprogram_cache, prefix);
}
}
break;
Expand All @@ -573,14 +691,16 @@ namespace libdwarf {
std::vector<stacktrace_frame>& inlines
) {
if(get_cache_mode() == cache_mode::prioritize_memory) {
retrieve_symbol_walk(cu_die, cu_die, pc, dwversion, frame, inlines);
std::string prefix;
retrieve_symbol_walk(cu_die, cu_die, pc, dwversion, frame, inlines, prefix);
} else {
auto off = cu_die.get_global_offset();
auto it = subprograms_cache.find(off);
if(it == subprograms_cache.end()) {
// TODO: Refactor. Do the sort in the preprocess function and return the vec directly.
subprogram_map subprogram_cache;
preprocess_subprograms(cu_die, cu_die, dwversion, subprogram_cache);
std::string prefix;
preprocess_subprograms(cu_die, cu_die, dwversion, subprogram_cache, prefix);
subprogram_cache.finalize();
subprograms_cache.emplace(off, std::move(subprogram_cache));
it = subprograms_cache.find(off);
Expand Down
4 changes: 4 additions & 0 deletions test/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -87,6 +87,7 @@ function(test_cpptrace)
unit/tracing/try_catch.cpp
unit/tracing/traced_exception.cpp
unit/tracing/rethrow.cpp
unit/tracing/namespace_resolution.cpp
unit/internals/optional.cpp
unit/internals/lru_cache.cpp
unit/internals/result.cpp
Expand Down Expand Up @@ -117,6 +118,9 @@ function(test_cpptrace)
if(CPPTRACE_BUILD_NO_SYMBOLS)
target_compile_definitions("${CPPTRACE_TEST_NAME}" PRIVATE CPPTRACE_BUILD_NO_SYMBOLS)
endif()
if(CPPTRACE_GET_SYMBOLS_WITH_LIBDWARF)
target_compile_definitions("${CPPTRACE_TEST_NAME}" PRIVATE CPPTRACE_GET_SYMBOLS_WITH_LIBDWARF)
endif()
target_include_directories("${CPPTRACE_TEST_NAME}" PRIVATE ../src)
add_test(NAME ${CPPTRACE_TEST_NAME} COMMAND ${CPPTRACE_TEST_NAME})
endfunction()
Expand Down
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