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7 changes: 5 additions & 2 deletions lldb/include/lldb/Core/ModuleList.h
Original file line number Diff line number Diff line change
Expand Up @@ -477,7 +477,7 @@ class ModuleList {

size_t Remove(ModuleList &module_list);

bool RemoveIfOrphaned(const Module *module_ptr);
bool RemoveIfOrphaned(const lldb::ModuleWP module_ptr);

size_t RemoveOrphans(bool mandatory);

Expand Down Expand Up @@ -531,7 +531,7 @@ class ModuleList {

static size_t RemoveOrphanSharedModules(bool mandatory);

static bool RemoveSharedModuleIfOrphaned(const Module *module_ptr);
static bool RemoveSharedModuleIfOrphaned(const lldb::ModuleWP module_ptr);

/// Applies 'callback' to each module in this ModuleList.
/// If 'callback' returns false, iteration terminates.
Expand Down Expand Up @@ -575,6 +575,9 @@ class ModuleList {

Notifier *m_notifier = nullptr;

/// An orphaned module that lives only in the ModuleList has a count of 1.
static constexpr long kUseCountModuleListOrphaned = 1;

public:
typedef LockingAdaptedIterable<std::recursive_mutex, collection>
ModuleIterable;
Expand Down
264 changes: 248 additions & 16 deletions lldb/source/Core/ModuleList.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -503,17 +503,20 @@ bool ModuleList::ReplaceModule(const lldb::ModuleSP &old_module_sp,
return true;
}

bool ModuleList::RemoveIfOrphaned(const Module *module_ptr) {
if (module_ptr) {
bool ModuleList::RemoveIfOrphaned(const ModuleWP module_wp) {
if (auto module_sp = module_wp.lock()) {
std::lock_guard<std::recursive_mutex> guard(m_modules_mutex);
collection::iterator pos, end = m_modules.end();
for (pos = m_modules.begin(); pos != end; ++pos) {
if (pos->get() == module_ptr) {
if (pos->use_count() == 1) {
if (pos->get() == module_sp.get()) {
// Since module_sp increases the refcount by 1, the use count should be
// the regular use count + 1.
constexpr long kUseCountOrphaned = kUseCountModuleListOrphaned + 1;
if (pos->use_count() == kUseCountOrphaned) {
pos = RemoveImpl(pos);
return true;
} else
return false;
}
return false;
}
}
}
Expand All @@ -540,7 +543,7 @@ size_t ModuleList::RemoveOrphans(bool mandatory) {
made_progress = false;
collection::iterator pos = m_modules.begin();
while (pos != m_modules.end()) {
if (pos->use_count() == 1) {
if (pos->use_count() == kUseCountModuleListOrphaned) {
pos = RemoveImpl(pos);
++remove_count;
// We did make progress.
Expand Down Expand Up @@ -1017,8 +1020,238 @@ size_t ModuleList::GetIndexForModule(const Module *module) const {
}

namespace {
/// A wrapper around ModuleList for shared modules. Provides fast lookups for
/// file-based ModuleSpec queries.
class SharedModuleList {
public:
/// Finds all the modules matching the module_spec, and adds them to \p
/// matching_module_list.
void FindModules(const ModuleSpec &module_spec,
ModuleList &matching_module_list) const {
std::lock_guard<std::recursive_mutex> guard(GetMutex());
// Try map first for performance - if found, skip expensive full list
// search.
FindModulesInMap(module_spec, matching_module_list);
if (!matching_module_list.IsEmpty())
return;
m_list.FindModules(module_spec, matching_module_list);
// Assert that modules were found in the list but not the map, it's
// because the module_spec has no filename or the found module has a
// different filename. For example, when searching by UUID and finding a
// module with an alias.
assert((matching_module_list.IsEmpty() ||
module_spec.GetFileSpec().GetFilename().IsEmpty() ||
module_spec.GetFileSpec().GetFilename() !=
matching_module_list.GetModuleAtIndex(0)
->GetFileSpec()
.GetFilename()) &&
"Search by name not found in SharedModuleList's map");
}

ModuleSP FindModule(const Module &module) {

std::lock_guard<std::recursive_mutex> guard(GetMutex());
if (ModuleSP result = FindModuleInMap(module))
return result;
return m_list.FindModule(&module);
}

// UUID searches bypass map since UUIDs aren't indexed by filename.
ModuleSP FindModule(const UUID &uuid) const {
return m_list.FindModule(uuid);
}

void Append(const ModuleSP &module_sp, bool use_notifier) {
if (!module_sp)
return;
std::lock_guard<std::recursive_mutex> guard(GetMutex());
m_list.Append(module_sp, use_notifier);
AddToMap(module_sp);
}

size_t RemoveOrphans(bool mandatory) {
std::unique_lock<std::recursive_mutex> lock(GetMutex(), std::defer_lock);
if (mandatory) {
lock.lock();
} else {
if (!lock.try_lock())
return 0;
}
size_t total_count = 0;
size_t run_count;
do {
// Remove indexed orphans first, then remove non-indexed orphans. This
// order is important because the shared count will be different if a
// module is indexed or not.
run_count = RemoveOrphansFromMapAndList();
run_count += m_list.RemoveOrphans(mandatory);
total_count += run_count;
// Because removing orphans might make new orphans, remove from both
// containers until a fixed-point is reached.
} while (run_count != 0);

return total_count;
}

bool Remove(const ModuleSP &module_sp, bool use_notifier = true) {
if (!module_sp)
return false;
std::lock_guard<std::recursive_mutex> guard(GetMutex());
RemoveFromMap(module_sp);
return m_list.Remove(module_sp, use_notifier);
}

void ReplaceEquivalent(const ModuleSP &module_sp,
llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules) {
std::lock_guard<std::recursive_mutex> guard(GetMutex());
m_list.ReplaceEquivalent(module_sp, old_modules);
ReplaceEquivalentInMap(module_sp);
}

bool RemoveIfOrphaned(const ModuleWP module_wp) {
std::lock_guard<std::recursive_mutex> guard(GetMutex());
RemoveFromMap(module_wp, /*if_orphaned=*/true);
return m_list.RemoveIfOrphaned(module_wp);
}

std::recursive_mutex &GetMutex() const { return m_list.GetMutex(); }

private:
ModuleSP FindModuleInMap(const Module &module) const {
if (!module.GetFileSpec().GetFilename())
return ModuleSP();
ConstString name = module.GetFileSpec().GetFilename();
auto it = m_name_to_modules.find(name);
if (it == m_name_to_modules.end())
return ModuleSP();
const llvm::SmallVectorImpl<ModuleSP> &vector = it->second;
for (const ModuleSP &module_sp : vector) {
if (module_sp.get() == &module)
return module_sp;
}
return ModuleSP();
}

void FindModulesInMap(const ModuleSpec &module_spec,
ModuleList &matching_module_list) const {
auto it = m_name_to_modules.find(module_spec.GetFileSpec().GetFilename());
if (it == m_name_to_modules.end())
return;
const llvm::SmallVectorImpl<ModuleSP> &vector = it->second;
for (const ModuleSP &module_sp : vector) {
if (module_sp->MatchesModuleSpec(module_spec))
matching_module_list.Append(module_sp);
}
}

void AddToMap(const ModuleSP &module_sp) {
ConstString name = module_sp->GetFileSpec().GetFilename();
if (name.IsEmpty())
return;
m_name_to_modules[name].push_back(module_sp);
}

void RemoveFromMap(const ModuleWP module_wp, bool if_orphaned = false) {
if (auto module_sp = module_wp.lock()) {
ConstString name = module_sp->GetFileSpec().GetFilename();
if (!m_name_to_modules.contains(name))
return;
llvm::SmallVectorImpl<ModuleSP> &vec = m_name_to_modules[name];
for (auto *it = vec.begin(); it != vec.end(); ++it) {
if (it->get() == module_sp.get()) {
// Since module_sp increases the refcount by 1, the use count should
// be the regular use count + 1.
constexpr long kUseCountOrphaned =
kUseCountSharedModuleListOrphaned + 1;
if (!if_orphaned || it->use_count() == kUseCountOrphaned) {
vec.erase(it);
break;
}
}
}
}
}

void ReplaceEquivalentInMap(const ModuleSP &module_sp) {
RemoveEquivalentModulesFromMap(module_sp);
AddToMap(module_sp);
}

void RemoveEquivalentModulesFromMap(const ModuleSP &module_sp) {
ConstString name = module_sp->GetFileSpec().GetFilename();
if (name.IsEmpty())
return;

auto it = m_name_to_modules.find(name);
if (it == m_name_to_modules.end())
return;

// First remove any equivalent modules. Equivalent modules are modules
// whose path, platform path and architecture match.
ModuleSpec equivalent_module_spec(module_sp->GetFileSpec(),
module_sp->GetArchitecture());
equivalent_module_spec.GetPlatformFileSpec() =
module_sp->GetPlatformFileSpec();

llvm::SmallVectorImpl<ModuleSP> &vec = it->second;
llvm::erase_if(vec, [&equivalent_module_spec](ModuleSP &element) {
return element->MatchesModuleSpec(equivalent_module_spec);
});
}

/// Remove orphans from the vector and return the removed modules.
ModuleList RemoveOrphansFromVector(llvm::SmallVectorImpl<ModuleSP> &vec) {
// remove_if moves the elements that match the condition to the end of the
// container, and returns an iterator to the first element that was moved.
auto *to_remove_start = llvm::remove_if(vec, [](const ModuleSP &module) {
return module.use_count() == kUseCountSharedModuleListOrphaned;
});

ModuleList to_remove;
for (ModuleSP *it = to_remove_start; it != vec.end(); ++it)
to_remove.Append(*it);

vec.erase(to_remove_start, vec.end());
return to_remove;
}

/// Remove orphans that exist in both the map and list. This does not remove
/// any orphans that exist exclusively on the list.
///
/// The mutex must be locked by the caller.
int RemoveOrphansFromMapAndList() {
// Modules might hold shared pointers to other modules, so removing one
// module might orphan other modules. Keep removing modules until
// there are no further modules that can be removed.
int remove_count = 0;
int previous_remove_count;
do {
previous_remove_count = remove_count;
for (auto &[name, vec] : m_name_to_modules) {
if (vec.empty())
continue;
ModuleList to_remove = RemoveOrphansFromVector(vec);
remove_count += to_remove.GetSize();
m_list.Remove(to_remove);
}
// Break when fixed-point is reached.
} while (previous_remove_count != remove_count);

return remove_count;
}

ModuleList m_list;

/// A hash map from a module's filename to all the modules that share that
/// filename, for fast module lookups by name.
llvm::DenseMap<ConstString, llvm::SmallVector<ModuleSP, 1>> m_name_to_modules;

/// The use count of a module held only by m_list and m_name_to_modules.
static constexpr long kUseCountSharedModuleListOrphaned = 2;
};

struct SharedModuleListInfo {
ModuleList module_list;
SharedModuleList module_list;
ModuleListProperties module_list_properties;
};
}
Expand All @@ -1036,7 +1269,7 @@ static SharedModuleListInfo &GetSharedModuleListInfo()
return *g_shared_module_list_info;
}

static ModuleList &GetSharedModuleList() {
static SharedModuleList &GetSharedModuleList() {
return GetSharedModuleListInfo().module_list;
}

Expand All @@ -1046,8 +1279,8 @@ ModuleListProperties &ModuleList::GetGlobalModuleListProperties() {

bool ModuleList::ModuleIsInCache(const Module *module_ptr) {
if (module_ptr) {
ModuleList &shared_module_list = GetSharedModuleList();
return shared_module_list.FindModule(module_ptr).get() != nullptr;
SharedModuleList &shared_module_list = GetSharedModuleList();
return shared_module_list.FindModule(*module_ptr).get() != nullptr;
}
return false;
}
Expand All @@ -1070,9 +1303,8 @@ ModuleList::GetSharedModule(const ModuleSpec &module_spec, ModuleSP &module_sp,
const FileSpecList *module_search_paths_ptr,
llvm::SmallVectorImpl<lldb::ModuleSP> *old_modules,
bool *did_create_ptr, bool always_create) {
ModuleList &shared_module_list = GetSharedModuleList();
std::lock_guard<std::recursive_mutex> guard(
shared_module_list.m_modules_mutex);
SharedModuleList &shared_module_list = GetSharedModuleList();
std::lock_guard<std::recursive_mutex> guard(shared_module_list.GetMutex());
char path[PATH_MAX];

Status error;
Expand Down Expand Up @@ -1316,8 +1548,8 @@ bool ModuleList::RemoveSharedModule(lldb::ModuleSP &module_sp) {
return GetSharedModuleList().Remove(module_sp);
}

bool ModuleList::RemoveSharedModuleIfOrphaned(const Module *module_ptr) {
return GetSharedModuleList().RemoveIfOrphaned(module_ptr);
bool ModuleList::RemoveSharedModuleIfOrphaned(const ModuleWP module_wp) {
return GetSharedModuleList().RemoveIfOrphaned(module_wp);
}

bool ModuleList::LoadScriptingResourcesInTarget(Target *target,
Expand Down
4 changes: 2 additions & 2 deletions lldb/source/Target/Target.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -2596,9 +2596,9 @@ ModuleSP Target::GetOrCreateModule(const ModuleSpec &orig_module_spec,
m_images.Append(module_sp, notify);

for (ModuleSP &old_module_sp : replaced_modules) {
Module *old_module_ptr = old_module_sp.get();
auto old_module_wp = old_module_sp->weak_from_this();
old_module_sp.reset();
ModuleList::RemoveSharedModuleIfOrphaned(old_module_ptr);
ModuleList::RemoveSharedModuleIfOrphaned(old_module_wp);
}
} else
module_sp.reset();
Expand Down