luo980/cpptrace
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Optimize dwarf handling by caching line contexts so the line info table only has to be computed once per TU per object per trace

Browse Source
This commit is contained in:
Jeremy 2023-09-17 00:54:11 -04:00
parent e47cb7147d
commit e4eab1d426
No known key found for this signature in database
GPG Key ID: 19AA8270105E8EB4
1 changed files with 310 additions and 264 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

110
src/symbols/symbols_with_libdwarf.cpp
View File

@ -558,7 +558,55 @@ namespace libdwarf {
frame.symbol = name + "(" + join(params, ", ") + ")";*/
}
struct line_context {
Dwarf_Unsigned version;
Dwarf_Small table_count;
Dwarf_Line_Context ctx;
};
struct dwarf_resolver {
std::string obj_path;
Dwarf_Debug dbg;
std::unordered_map<Dwarf_Off, line_context> line_contexts;
CPPTRACE_FORCE_NO_INLINE
dwarf_resolver(const std::string& object_path) {
obj_path = object_path;
#if IS_APPLE
if(directory_exists(obj_path + ".dSYM")) {
obj_path += ".dSYM/Contents/Resources/DWARF/" + basename(object_path);
}
#endif
Dwarf_Ptr errarg = 0;
auto ret = dwarf_init_path(
obj_path.c_str(),
nullptr,
0,
DW_GROUPNUMBER_ANY,
err_handler,
errarg,
&dbg,
nullptr
);
if(ret == DW_DLV_NO_ENTRY) {
// fail, no debug info
} else if(ret != DW_DLV_OK) {
fprintf(stderr, "Error\n");
} else {
}
}
CPPTRACE_FORCE_NO_INLINE
~dwarf_resolver() {
dwarf_finish(dbg);
for(auto& entry : line_contexts) {
dwarf_srclines_dealloc_b(entry.second.ctx);
}
}
// returns true if this call found the symbol
CPPTRACE_FORCE_NO_INLINE
bool retrieve_symbol(
Dwarf_Debug dbg,
const die_object& die,
@ -570,7 +618,7 @@ namespace libdwarf {
walk_die_list(
dbg,
die,
[pc, dwversion, &frame, &found] (Dwarf_Debug dbg, const die_object& die) {
[this, pc, dwversion, &frame, &found] (Dwarf_Debug dbg, const die_object& die) {
if(dump_dwarf) {
fprintf(
stderr,
@ -618,6 +666,7 @@ namespace libdwarf {
return found;
}
CPPTRACE_FORCE_NO_INLINE
void retrieve_line_info(
Dwarf_Debug dbg,
const die_object& die,
@ -630,6 +679,14 @@ namespace libdwarf {
Dwarf_Line_Context ctxt;
Dwarf_Bool is_found = false;
(void)dwversion;
auto off = die.get_global_offset();
auto it = line_contexts.find(off);
if(it != line_contexts.end()) {
auto& entry = it->second;
version = entry.version;
table_count = entry.table_count;
ctxt = entry.ctx;
} else {
int ret = dwarf_srclines_b(
die.get(),
&version,
@ -637,10 +694,13 @@ namespace libdwarf {
&ctxt,
nullptr
);
line_contexts.insert({off, {version, table_count, ctxt}});
if(ret == DW_DLV_NO_ENTRY) {
fprintf(stderr, "dwarf_srclines_b error\n");
return;
}
}
if(table_count == 1) {
Dwarf_Line *linebuf = 0;
Dwarf_Signed linecount = 0;
@ -685,9 +745,9 @@ namespace libdwarf {
}
}
}
dwarf_srclines_dealloc_b(ctxt);
}
CPPTRACE_FORCE_NO_INLINE
void walk_compilation_units(Dwarf_Debug dbg, Dwarf_Addr pc, stacktrace_frame& frame) {
// 0 passed as the die to the first call of dwarf_siblingof_b immediately after dwarf_next_cu_header_d
// to fetch the cu die
@ -702,7 +762,7 @@ namespace libdwarf {
walk_die_list(
dbg,
cu_die,
[&frame, pc] (Dwarf_Debug dbg, const die_object& cu_die) {
[this, &frame, pc] (Dwarf_Debug dbg, const die_object& cu_die) {
Dwarf_Half offset_size = 0;
Dwarf_Half dwversion = 0;
dwarf_get_version_of_die(cu_die.get(), &dwversion, &offset_size);
@ -742,6 +802,7 @@ namespace libdwarf {
);
}
CPPTRACE_FORCE_NO_INLINE
void walk_dbg(Dwarf_Debug dbg, Dwarf_Addr pc, stacktrace_frame& frame) {
// libdwarf keeps track of where it is in the file, dwarf_next_cu_header_d is statefull
Dwarf_Unsigned next_cu_header;
@ -776,6 +837,7 @@ namespace libdwarf {
}
}
CPPTRACE_FORCE_NO_INLINE
void lookup_pc(
const char* object,
Dwarf_Addr pc,
@ -785,39 +847,15 @@ namespace libdwarf {
fprintf(stderr, "%s\n", object);
fprintf(stderr, "%llx\n", pc);
}
Dwarf_Debug dbg;
Dwarf_Ptr errarg = 0;
auto ret = dwarf_init_path(
object,
nullptr,
0,
DW_GROUPNUMBER_ANY,
err_handler,
errarg,
&dbg,
nullptr
);
if(ret == DW_DLV_NO_ENTRY) {
// fail, no debug info
} else if(ret != DW_DLV_OK) {
fprintf(stderr, "Error\n");
} else {
walk_dbg(dbg, pc, frame);
}
dwarf_finish(dbg);
}
CPPTRACE_FORCE_NO_INLINE
stacktrace_frame resolve_frame(const dlframe& frame_info) {
stacktrace_frame frame{};
frame.filename = frame_info.obj_path;
frame.symbol = frame_info.symbol;
frame.address = frame_info.raw_address;
std::string obj_path = frame_info.obj_path;
#if IS_APPLE
if(directory_exists(obj_path + ".dSYM")) {
obj_path += ".dSYM/Contents/Resources/DWARF/" + basename(frame_info.obj_path);
}
#endif
if(trace_dwarf) {
fprintf(
stderr,
@ -834,12 +872,20 @@ namespace libdwarf {
);
return frame;
}
};
CPPTRACE_FORCE_NO_INLINE
std::vector<stacktrace_frame> resolve_frames(const std::vector<void*>& frames) {
std::vector<stacktrace_frame> trace;
trace.reserve(frames.size());
for(const auto& frame : get_frames_object_info(frames)) {
trace.push_back(resolve_frame(frame));
std::vector<stacktrace_frame> trace(frames.size(), stacktrace_frame { 0, 0, 0, "", "" });
const auto dlframes = get_frames_object_info(frames);
for(const auto& obj_entry : collate_frames(dlframes, trace)) {
const auto& obj_name = obj_entry.first;
dwarf_resolver resolver(obj_name);
for(const auto& entry : obj_entry.second) {
const auto& dlframe = entry.first.get();
auto& frame = entry.second.get();
frame = resolver.resolve_frame(dlframe);
}
}
return trace;
}