Files
clang-p2996/lldb/source/Symbol/CompileUnit.cpp
Jeffrey Tan 7b81192d46 Introduce new symbol on-demand for debug info
This diff introduces a new symbol on-demand which skips
loading a module's debug info unless explicitly asked on
demand. This provides significant performance improvement
for application with dynamic linking mode which has large
number of modules.
The feature can be turned on with:
"settings set symbols.load-on-demand true"

The feature works by creating a new SymbolFileOnDemand class for
each module which wraps the actual SymbolFIle subclass as member
variable. By default, most virtual methods on SymbolFileOnDemand are
skipped so that it looks like there is no debug info for that module.
But once the module's debug info is explicitly requested to
be enabled (in the conditions mentioned below) SymbolFileOnDemand
will allow all methods to pass through and forward to the actual SymbolFile
which would hydrate module's debug info on-demand.

In an internal benchmark, we are seeing more than 95% improvement
for a 3000 modules application.

Currently we are providing several ways to on demand hydrate
a module's debug info:
* Source line breakpoint: matching in supported files
* Stack trace: resolving symbol context for an address
* Symbolic breakpoint: symbol table match guided promotion
* Global variable: symbol table match guided promotion

In all above situations the module's debug info will be on-demand
parsed and indexed.

Some follow-ups for this feature:
* Add a command that allows users to load debug info explicitly while using a
  new or existing command when this feature is enabled
* Add settings for "never load any of these executables in Symbols On Demand"
  that takes a list of globs
* Add settings for "always load the the debug info for executables in Symbols
  On Demand" that takes a list of globs
* Add a new column in "image list" that shows up by default when Symbols On
  Demand is enable to show the status for each shlib like "not enabled for
  this", "debug info off" and "debug info on" (with a single character to
  short string, not the ones I just typed)

Differential Revision: https://reviews.llvm.org/D121631
2022-04-26 10:42:06 -07:00

402 lines
13 KiB
C++

//===-- CompileUnit.cpp ---------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "lldb/Symbol/CompileUnit.h"
#include "lldb/Core/Module.h"
#include "lldb/Symbol/LineTable.h"
#include "lldb/Symbol/SymbolFile.h"
#include "lldb/Symbol/VariableList.h"
#include "lldb/Target/Language.h"
#include "lldb/Utility/Timer.h"
using namespace lldb;
using namespace lldb_private;
CompileUnit::CompileUnit(const lldb::ModuleSP &module_sp, void *user_data,
const char *pathname, const lldb::user_id_t cu_sym_id,
lldb::LanguageType language,
lldb_private::LazyBool is_optimized)
: CompileUnit(module_sp, user_data, FileSpec(pathname), cu_sym_id, language,
is_optimized) {}
CompileUnit::CompileUnit(const lldb::ModuleSP &module_sp, void *user_data,
const FileSpec &fspec, const lldb::user_id_t cu_sym_id,
lldb::LanguageType language,
lldb_private::LazyBool is_optimized)
: ModuleChild(module_sp), UserID(cu_sym_id), m_user_data(user_data),
m_language(language), m_flags(0), m_file_spec(fspec),
m_is_optimized(is_optimized) {
if (language != eLanguageTypeUnknown)
m_flags.Set(flagsParsedLanguage);
assert(module_sp);
}
void CompileUnit::CalculateSymbolContext(SymbolContext *sc) {
sc->comp_unit = this;
GetModule()->CalculateSymbolContext(sc);
}
ModuleSP CompileUnit::CalculateSymbolContextModule() { return GetModule(); }
CompileUnit *CompileUnit::CalculateSymbolContextCompileUnit() { return this; }
void CompileUnit::DumpSymbolContext(Stream *s) {
GetModule()->DumpSymbolContext(s);
s->Printf(", CompileUnit{0x%8.8" PRIx64 "}", GetID());
}
void CompileUnit::GetDescription(Stream *s,
lldb::DescriptionLevel level) const {
const char *language = GetCachedLanguage();
*s << "id = " << (const UserID &)*this << ", file = \""
<< this->GetPrimaryFile() << "\", language = \"" << language << '"';
}
void CompileUnit::ForeachFunction(
llvm::function_ref<bool(const FunctionSP &)> lambda) const {
std::vector<lldb::FunctionSP> sorted_functions;
sorted_functions.reserve(m_functions_by_uid.size());
for (auto &p : m_functions_by_uid)
sorted_functions.push_back(p.second);
llvm::sort(sorted_functions.begin(), sorted_functions.end(),
[](const lldb::FunctionSP &a, const lldb::FunctionSP &b) {
return a->GetID() < b->GetID();
});
for (auto &f : sorted_functions)
if (lambda(f))
return;
}
lldb::FunctionSP CompileUnit::FindFunction(
llvm::function_ref<bool(const FunctionSP &)> matching_lambda) {
LLDB_SCOPED_TIMER();
lldb::ModuleSP module = CalculateSymbolContextModule();
if (!module)
return {};
SymbolFile *symbol_file = module->GetSymbolFile();
if (!symbol_file)
return {};
// m_functions_by_uid is filled in lazily but we need all the entries.
symbol_file->ParseFunctions(*this);
for (auto &p : m_functions_by_uid) {
if (matching_lambda(p.second))
return p.second;
}
return {};
}
const char *CompileUnit::GetCachedLanguage() const {
if (m_flags.IsClear(flagsParsedLanguage))
return "<not loaded>";
return Language::GetNameForLanguageType(m_language);
}
// Dump the current contents of this object. No functions that cause on demand
// parsing of functions, globals, statics are called, so this is a good
// function to call to get an idea of the current contents of the CompileUnit
// object.
void CompileUnit::Dump(Stream *s, bool show_context) const {
const char *language = GetCachedLanguage();
s->Printf("%p: ", static_cast<const void *>(this));
s->Indent();
*s << "CompileUnit" << static_cast<const UserID &>(*this) << ", language = \""
<< language << "\", file = '" << GetPrimaryFile() << "'\n";
// m_types.Dump(s);
if (m_variables.get()) {
s->IndentMore();
m_variables->Dump(s, show_context);
s->IndentLess();
}
if (!m_functions_by_uid.empty()) {
s->IndentMore();
ForeachFunction([&s, show_context](const FunctionSP &f) {
f->Dump(s, show_context);
return false;
});
s->IndentLess();
s->EOL();
}
}
// Add a function to this compile unit
void CompileUnit::AddFunction(FunctionSP &funcSP) {
m_functions_by_uid[funcSP->GetID()] = funcSP;
}
FunctionSP CompileUnit::FindFunctionByUID(lldb::user_id_t func_uid) {
auto it = m_functions_by_uid.find(func_uid);
if (it == m_functions_by_uid.end())
return FunctionSP();
return it->second;
}
lldb::LanguageType CompileUnit::GetLanguage() {
if (m_language == eLanguageTypeUnknown) {
if (m_flags.IsClear(flagsParsedLanguage)) {
m_flags.Set(flagsParsedLanguage);
if (SymbolFile *symfile = GetModule()->GetSymbolFile())
m_language = symfile->ParseLanguage(*this);
}
}
return m_language;
}
LineTable *CompileUnit::GetLineTable() {
if (m_line_table_up == nullptr) {
if (m_flags.IsClear(flagsParsedLineTable)) {
m_flags.Set(flagsParsedLineTable);
if (SymbolFile *symfile = GetModule()->GetSymbolFile())
symfile->ParseLineTable(*this);
}
}
return m_line_table_up.get();
}
void CompileUnit::SetLineTable(LineTable *line_table) {
if (line_table == nullptr)
m_flags.Clear(flagsParsedLineTable);
else
m_flags.Set(flagsParsedLineTable);
m_line_table_up.reset(line_table);
}
void CompileUnit::SetSupportFiles(const FileSpecList &support_files) {
m_support_files = support_files;
}
void CompileUnit::SetSupportFiles(FileSpecList &&support_files) {
m_support_files = std::move(support_files);
}
DebugMacros *CompileUnit::GetDebugMacros() {
if (m_debug_macros_sp.get() == nullptr) {
if (m_flags.IsClear(flagsParsedDebugMacros)) {
m_flags.Set(flagsParsedDebugMacros);
if (SymbolFile *symfile = GetModule()->GetSymbolFile())
symfile->ParseDebugMacros(*this);
}
}
return m_debug_macros_sp.get();
}
void CompileUnit::SetDebugMacros(const DebugMacrosSP &debug_macros_sp) {
if (debug_macros_sp.get() == nullptr)
m_flags.Clear(flagsParsedDebugMacros);
else
m_flags.Set(flagsParsedDebugMacros);
m_debug_macros_sp = debug_macros_sp;
}
VariableListSP CompileUnit::GetVariableList(bool can_create) {
if (m_variables.get() == nullptr && can_create) {
SymbolContext sc;
CalculateSymbolContext(&sc);
assert(sc.module_sp);
sc.module_sp->GetSymbolFile()->ParseVariablesForContext(sc);
}
return m_variables;
}
std::vector<uint32_t> FindFileIndexes(const FileSpecList &files, const FileSpec &file) {
std::vector<uint32_t> result;
uint32_t idx = -1;
while ((idx = files.FindFileIndex(idx + 1, file, /*full=*/true)) !=
UINT32_MAX)
result.push_back(idx);
return result;
}
uint32_t CompileUnit::FindLineEntry(uint32_t start_idx, uint32_t line,
const FileSpec *file_spec_ptr, bool exact,
LineEntry *line_entry_ptr) {
if (!file_spec_ptr)
file_spec_ptr = &GetPrimaryFile();
std::vector<uint32_t> file_indexes = FindFileIndexes(GetSupportFiles(), *file_spec_ptr);
if (file_indexes.empty())
return UINT32_MAX;
// TODO: Handle SourceLocationSpec column information
SourceLocationSpec location_spec(*file_spec_ptr, line, /*column=*/llvm::None,
/*check_inlines=*/false, exact);
LineTable *line_table = GetLineTable();
if (line_table)
return line_table->FindLineEntryIndexByFileIndex(
start_idx, file_indexes, location_spec, line_entry_ptr);
return UINT32_MAX;
}
void CompileUnit::ResolveSymbolContext(
const SourceLocationSpec &src_location_spec,
SymbolContextItem resolve_scope, SymbolContextList &sc_list) {
const FileSpec file_spec = src_location_spec.GetFileSpec();
const uint32_t line = src_location_spec.GetLine().getValueOr(0);
const bool check_inlines = src_location_spec.GetCheckInlines();
// First find all of the file indexes that match our "file_spec". If
// "file_spec" has an empty directory, then only compare the basenames when
// finding file indexes
std::vector<uint32_t> file_indexes;
bool file_spec_matches_cu_file_spec =
FileSpec::Match(file_spec, this->GetPrimaryFile());
// If we are not looking for inlined functions and our file spec doesn't
// match then we are done...
if (!file_spec_matches_cu_file_spec && !check_inlines)
return;
SymbolContext sc(GetModule());
sc.comp_unit = this;
if (line == 0) {
if (file_spec_matches_cu_file_spec && !check_inlines) {
// only append the context if we aren't looking for inline call sites by
// file and line and if the file spec matches that of the compile unit
sc_list.Append(sc);
}
return;
}
uint32_t file_idx =
GetSupportFiles().FindFileIndex(0, file_spec, true);
while (file_idx != UINT32_MAX) {
file_indexes.push_back(file_idx);
file_idx = GetSupportFiles().FindFileIndex(file_idx + 1, file_spec, true);
}
const size_t num_file_indexes = file_indexes.size();
if (num_file_indexes == 0)
return;
// Found a matching source file in this compile unit load its debug info.
GetModule()->GetSymbolFile()->SetLoadDebugInfoEnabled();
LineTable *line_table = sc.comp_unit->GetLineTable();
if (line_table == nullptr) {
if (file_spec_matches_cu_file_spec && !check_inlines) {
sc_list.Append(sc);
}
return;
}
uint32_t line_idx;
LineEntry line_entry;
if (num_file_indexes == 1) {
// We only have a single support file that matches, so use the line
// table function that searches for a line entries that match a single
// support file index
line_idx = line_table->FindLineEntryIndexByFileIndex(
0, file_indexes.front(), src_location_spec, &line_entry);
} else {
// We found multiple support files that match "file_spec" so use the
// line table function that searches for a line entries that match a
// multiple support file indexes.
line_idx = line_table->FindLineEntryIndexByFileIndex(
0, file_indexes, src_location_spec, &line_entry);
}
// If "exact == true", then "found_line" will be the same as "line". If
// "exact == false", the "found_line" will be the closest line entry
// with a line number greater than "line" and we will use this for our
// subsequent line exact matches below.
const bool inlines = false;
const bool exact = true;
const llvm::Optional<uint16_t> column =
src_location_spec.GetColumn().hasValue()
? llvm::Optional<uint16_t>(line_entry.column)
: llvm::None;
SourceLocationSpec found_entry(line_entry.file, line_entry.line, column,
inlines, exact);
while (line_idx != UINT32_MAX) {
// If they only asked for the line entry, then we're done, we can
// just copy that over. But if they wanted more than just the line
// number, fill it in.
if (resolve_scope == eSymbolContextLineEntry) {
sc.line_entry = line_entry;
} else {
line_entry.range.GetBaseAddress().CalculateSymbolContext(&sc,
resolve_scope);
}
sc_list.Append(sc);
if (num_file_indexes == 1)
line_idx = line_table->FindLineEntryIndexByFileIndex(
line_idx + 1, file_indexes.front(), found_entry, &line_entry);
else
line_idx = line_table->FindLineEntryIndexByFileIndex(
line_idx + 1, file_indexes, found_entry, &line_entry);
}
}
bool CompileUnit::GetIsOptimized() {
if (m_is_optimized == eLazyBoolCalculate) {
m_is_optimized = eLazyBoolNo;
if (SymbolFile *symfile = GetModule()->GetSymbolFile()) {
if (symfile->ParseIsOptimized(*this))
m_is_optimized = eLazyBoolYes;
}
}
return m_is_optimized;
}
void CompileUnit::SetVariableList(VariableListSP &variables) {
m_variables = variables;
}
const std::vector<SourceModule> &CompileUnit::GetImportedModules() {
if (m_imported_modules.empty() &&
m_flags.IsClear(flagsParsedImportedModules)) {
m_flags.Set(flagsParsedImportedModules);
if (SymbolFile *symfile = GetModule()->GetSymbolFile()) {
SymbolContext sc;
CalculateSymbolContext(&sc);
symfile->ParseImportedModules(sc, m_imported_modules);
}
}
return m_imported_modules;
}
bool CompileUnit::ForEachExternalModule(
llvm::DenseSet<SymbolFile *> &visited_symbol_files,
llvm::function_ref<bool(Module &)> lambda) {
if (SymbolFile *symfile = GetModule()->GetSymbolFile())
return symfile->ForEachExternalModule(*this, visited_symbol_files, lambda);
return false;
}
const FileSpecList &CompileUnit::GetSupportFiles() {
if (m_support_files.GetSize() == 0) {
if (m_flags.IsClear(flagsParsedSupportFiles)) {
m_flags.Set(flagsParsedSupportFiles);
if (SymbolFile *symfile = GetModule()->GetSymbolFile())
symfile->ParseSupportFiles(*this, m_support_files);
}
}
return m_support_files;
}
void *CompileUnit::GetUserData() const { return m_user_data; }