[Lldb-commits] [lldb] [NFC][lldb] Speed up lookup of shared modules (PR #152054)

[Jonas Devlieghere via lldb-commits]

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@@ -755,11 +755,237 @@ 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 index first for performance - if found, skip expensive full list
+    // search
+    if (FindModulesInIndex(module_spec, matching_module_list))
+      return;
+    m_list.FindModules(module_spec, matching_module_list);
+    // Assertion validates that if we found modules in the list but not the
+    // index, it's because the module_spec has no filename or the found module
+    // has a different filename (e.g., 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 index");
+  }
+
+  ModuleSP FindModule(const Module *module_ptr) {
+    if (!module_ptr)
+      return ModuleSP();
+
+    std::lock_guard<std::recursive_mutex> guard(GetMutex());
+    // Try index first, fallback to full list search
+    if (ModuleSP result = FindModuleInIndex(module_ptr))
+      return result;
+    return m_list.FindModule(module_ptr);
+  }
+
+  // UUID searches bypass index 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);
+    AddToIndex(module_sp);
+  }
+
+  size_t RemoveOrphans(bool mandatory) {
+    std::unique_lock<std::recursive_mutex> lock(GetMutex(), std::defer_lock);
+    if (mandatory) {
+      lock.lock();
+    } else {
+      // Skip orphan removal if mutex unavailable (non-blocking)
+      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 if indexed or not.
+      run_count = RemoveOrphansFromIndexAndList();
+      run_count += m_list.RemoveOrphans(mandatory);
+      total_count += run_count;
+      // Because removing orphans might make new orphans, we must continuously
+      // remove from both until both operations fail to remove new orphans.
+    } 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());
+    RemoveFromIndex(module_sp.get());
+    bool success = m_list.Remove(module_sp, use_notifier);
+    return success;
+  }
+
+  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);
+    ReplaceEquivalentInIndex(module_sp);
+  }
+
+  bool RemoveIfOrphaned(const Module *module_ptr) {
+    std::lock_guard<std::recursive_mutex> guard(GetMutex());
+    RemoveFromIndex(module_ptr, /*if_orphaned =*/true);
+    bool result = m_list.RemoveIfOrphaned(module_ptr);
+    return result;
+  }
+
+  std::recursive_mutex &GetMutex() const { return m_list.GetMutex(); }
+
+private:
+  ModuleSP FindModuleInIndex(const Module *module_ptr) {
+    if (!module_ptr->GetFileSpec().GetFilename())
+      return ModuleSP();
+    ConstString name = module_ptr->GetFileSpec().GetFilename();
+    auto it = m_index.find(name);
+    if (it != m_index.end()) {
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JDevlieghere wrote:

Invert & early return?

https://github.com/llvm/llvm-project/pull/152054