[cpu-profiler] Reference counting for code entries

To enable deallocation of CodeEntry objects after they're no longer
being referenced by an active profile or alive on the heap, replace the
|used| bit with a proper reference count maintained by a CodeMap.

Bug: v8:11054
Change-Id: Id3d5941e509504415692f833e406ecdd2553d426
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2945541Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Andrew Comminos <acomminos@fb.com>
Cr-Commit-Position: refs/heads/master@{#75164}

src/profiler/cpu-profiler-inl.h

@@ -53,8 +53,8 @@ void ReportBuiltinEventRecord::UpdateCodeMap(CodeMap* code_map) {
   if (builtin == Builtin::kGenericJSToWasmWrapper) {
     // Make sure to add the generic js-to-wasm wrapper builtin, because that
     // one is supposed to show up in profiles.
-    entry =
-        new CodeEntry(CodeEventListener::BUILTIN_TAG, Builtins::name(builtin));
+    entry = code_map->code_entries().Create(CodeEventListener::BUILTIN_TAG,
+                                            Builtins::name(builtin));
     code_map->AddCode(instruction_start, entry, instruction_size);
   }
 #endif  // V8_ENABLE_WEBASSEMBLY

src/profiler/cpu-profiler.cc

@@ -336,9 +336,11 @@ void* SamplingEventsProcessor::operator new(size_t size) {
 
 void SamplingEventsProcessor::operator delete(void* ptr) { AlignedFree(ptr); }
 
-ProfilerCodeObserver::ProfilerCodeObserver(Isolate* isolate)
+ProfilerCodeObserver::ProfilerCodeObserver(Isolate* isolate,
+                                           CodeEntryStorage& storage)
     : isolate_(isolate),
-      code_map_(strings_),
+      code_entries_(storage),
+      code_map_(storage),
       weak_code_registry_(isolate),
       processor_(nullptr) {
   CreateEntriesForRuntimeCallStats();
@@ -350,7 +352,7 @@ void ProfilerCodeObserver::ClearCodeMap() {
   code_map_.Clear();
   // We don't currently expect any references to refcounted strings to be
   // maintained with zero profiles after the code map is cleared.
-  DCHECK(strings_.empty());
+  DCHECK(code_entries_.strings().empty());
 }
 
 void ProfilerCodeObserver::CodeEventHandler(
@@ -385,8 +387,8 @@ void ProfilerCodeObserver::CreateEntriesForRuntimeCallStats() {
   for (int i = 0; i < RuntimeCallStats::kNumberOfCounters; ++i) {
     RuntimeCallCounter* counter = rcs->GetCounter(i);
     DCHECK(counter->name());
-    auto entry = new CodeEntry(CodeEventListener::FUNCTION_TAG, counter->name(),
-                               "native V8Runtime");
+    auto entry = code_entries_.Create(CodeEventListener::FUNCTION_TAG,
+                                      counter->name(), "native V8Runtime");
     code_map_.AddCode(reinterpret_cast<Address>(counter), entry, 1);
   }
 #endif  // V8_RUNTIME_CALL_STATS
@@ -473,7 +475,7 @@ CpuProfiler::CpuProfiler(Isolate* isolate, CpuProfilingNamingMode naming_mode,
                          CpuProfilingLoggingMode logging_mode)
     : CpuProfiler(isolate, naming_mode, logging_mode,
                   new CpuProfilesCollection(isolate), nullptr, nullptr,
-                  new ProfilerCodeObserver(isolate)) {}
+                  new ProfilerCodeObserver(isolate, code_entries_)) {}
 
 CpuProfiler::CpuProfiler(Isolate* isolate, CpuProfilingNamingMode naming_mode,
                          CpuProfilingLoggingMode logging_mode,
@@ -529,7 +531,7 @@ void CpuProfiler::EnableLogging() {
 
   if (!profiler_listener_) {
     profiler_listener_.reset(new ProfilerListener(
-        isolate_, code_observer_.get(), *code_observer_->strings(),
+        isolate_, code_observer_.get(), *code_observer_->code_entries(),
         *code_observer_->weak_code_registry(), naming_mode_));
   }
   profiling_scope_.reset(

src/profiler/cpu-profiler.h

@@ -256,17 +256,17 @@ class V8_EXPORT_PRIVATE SamplingEventsProcessor
                                      // low sampling intervals on Windows.
 };
 
-// Builds and maintains a CodeMap tracking code objects on the VM heap, as well
-// as strings owned by them. While alive, logs generated code, callbacks, and
-// builtins from the isolate. Redirects events to the profiler events
-// processor when present.
+// Builds and maintains a CodeMap tracking code objects on the VM heap. While
+// alive, logs generated code, callbacks, and builtins from the isolate.
+// Redirects events to the profiler events processor when present. CodeEntry
+// lifetime is associated with the given CodeEntryStorage.
 class V8_EXPORT_PRIVATE ProfilerCodeObserver : public CodeEventObserver {
  public:
-  explicit ProfilerCodeObserver(Isolate*);
+  explicit ProfilerCodeObserver(Isolate*, CodeEntryStorage&);
 
   void CodeEventHandler(const CodeEventsContainer& evt_rec) override;
+  CodeEntryStorage* code_entries() { return &code_entries_; }
   CodeMap* code_map() { return &code_map_; }
-  StringsStorage* strings() { return &strings_; }
   WeakCodeRegistry* weak_code_registry() { return &weak_code_registry_; }
 
   void ClearCodeMap();
@@ -290,7 +290,7 @@ class V8_EXPORT_PRIVATE ProfilerCodeObserver : public CodeEventObserver {
   void clear_processor() { processor_ = nullptr; }
 
   Isolate* const isolate_;
-  StringsStorage strings_;
+  CodeEntryStorage& code_entries_;
   CodeMap code_map_;
   WeakCodeRegistry weak_code_registry_;
   ProfilerEventsProcessor* processor_;
@@ -361,6 +361,7 @@ class V8_EXPORT_PRIVATE CpuProfiler {
   Symbolizer* symbolizer() const { return symbolizer_.get(); }
   ProfilerEventsProcessor* processor() const { return processor_.get(); }
   Isolate* isolate() const { return isolate_; }
+  CodeEntryStorage* code_entries() { return &code_entries_; }
 
   ProfilerListener* profiler_listener_for_test() const {
     return profiler_listener_.get();
@@ -389,6 +390,11 @@ class V8_EXPORT_PRIVATE CpuProfiler {
   // Sampling interval to which per-profile sampling intervals will be clamped
   // to a multiple of, or used as the default if unspecified.
   base::TimeDelta base_sampling_interval_;
+
+  // Storage for CodeEntry objects allocated by the profiler. May live for
+  // multiple profiling sessions, independent of heap listener state.
+  CodeEntryStorage code_entries_;
+
   std::unique_ptr<ProfilerCodeObserver> code_observer_;
   std::unique_ptr<CpuProfilesCollection> profiles_;
   std::unique_ptr<Symbolizer> symbolizer_;

src/profiler/profile-generator-inl.h

@@ -38,6 +38,7 @@ ProfileNode::ProfileNode(ProfileTree* tree, CodeEntry* entry,
       parent_(parent),
       id_(tree->next_node_id()) {
   tree_->EnqueueNode(this);
+  if (tree_->code_entries()) tree_->code_entries()->AddRef(entry_);
 }
 
 inline Isolate* ProfileNode::isolate() const { return tree_->isolate(); }

src/profiler/profile-generator.cc

@@ -231,6 +231,8 @@ CodeEntry::RareData* CodeEntry::EnsureRareData() {
 }
 
 void CodeEntry::ReleaseStrings(StringsStorage& strings) {
+  DCHECK_EQ(ref_count_, 0UL);
+
   if (name_) {
     strings.Release(name_);
     name_ = nullptr;
@@ -296,6 +298,10 @@ void CodeEntry::print() const {
   base::OS::Print("\n");
 }
 
+ProfileNode::~ProfileNode() {
+  if (tree_->code_entries()) tree_->code_entries()->DecRef(entry_);
+}
+
 CpuProfileNode::SourceType ProfileNode::source_type() const {
   // Handle metadata and VM state code entry types.
   if (entry_ == CodeEntry::program_entry() ||
@@ -433,10 +439,11 @@ class DeleteNodesCallback {
   void AfterChildTraversed(ProfileNode*, ProfileNode*) { }
 };
 
-ProfileTree::ProfileTree(Isolate* isolate)
+ProfileTree::ProfileTree(Isolate* isolate, CodeEntryStorage* storage)
     : next_node_id_(1),
       root_(new ProfileNode(this, CodeEntry::root_entry(), nullptr)),
-      isolate_(isolate) {}
+      isolate_(isolate),
+      code_entries_(storage) {}
 
 ProfileTree::~ProfileTree() {
   DeleteNodesCallback cb;
@@ -548,7 +555,7 @@ CpuProfile::CpuProfile(CpuProfiler* profiler, const char* title,
       options_(options),
       delegate_(std::move(delegate)),
       start_time_(base::TimeTicks::HighResolutionNow()),
-      top_down_(profiler->isolate()),
+      top_down_(profiler->isolate(), profiler->code_entries()),
       profiler_(profiler),
       streaming_next_sample_(0),
       id_(++last_id_) {
@@ -739,31 +746,32 @@ void CpuProfile::Print() const {
   ProfilerStats::Instance()->Clear();
 }
 
-CodeMap::CodeMap(StringsStorage& function_and_resource_names)
-    : function_and_resource_names_(function_and_resource_names) {}
+void CodeEntryStorage::AddRef(CodeEntry* entry) {
+  if (entry->is_ref_counted()) entry->AddRef();
+}
+
+void CodeEntryStorage::DecRef(CodeEntry* entry) {
+  if (entry->is_ref_counted() && entry->DecRef() == 0) {
+    entry->ReleaseStrings(function_and_resource_names_);
+    delete entry;
+  }
+}
+
+CodeMap::CodeMap(CodeEntryStorage& storage) : code_entries_(storage) {}
 
 CodeMap::~CodeMap() { Clear(); }
 
 void CodeMap::Clear() {
   for (auto& slot : code_map_) {
     if (CodeEntry* entry = slot.second.entry) {
-      entry->ReleaseStrings(function_and_resource_names_);
-      delete entry;
+      code_entries_.DecRef(entry);
     } else {
       // We expect all entries in the code mapping to contain a CodeEntry.
       UNREACHABLE();
     }
   }
 
-  // Free all CodeEntry objects that are no longer in the map, but in a profile.
-  // TODO(acomminos): Remove this deque after we refcount CodeEntry objects.
-  for (CodeEntry* entry : used_entries_) {
-    DCHECK(entry->used());
-    DeleteCodeEntry(entry);
-  }
-
   code_map_.clear();
-  used_entries_.clear();
 }
 
 void CodeMap::AddCode(Address addr, CodeEntry* entry, unsigned size) {
@@ -775,11 +783,7 @@ bool CodeMap::RemoveCode(CodeEntry* entry) {
   auto range = code_map_.equal_range(entry->instruction_start());
   for (auto i = range.first; i != range.second; ++i) {
     if (i->second.entry == entry) {
-      if (!entry->used()) {
-        DeleteCodeEntry(entry);
-      } else {
-        used_entries_.push_back(entry);
-      }
+      code_entries_.DecRef(entry);
       code_map_.erase(i);
       return true;
     }
@@ -795,11 +799,7 @@ void CodeMap::ClearCodesInRange(Address start, Address end) {
   }
   auto right = left;
   for (; right != code_map_.end() && right->first < end; ++right) {
-    if (!right->second.entry->used()) {
-      DeleteCodeEntry(right->second.entry);
-    } else {
-      used_entries_.push_back(right->second.entry);
-    }
+    code_entries_.DecRef(right->second.entry);
   }
   code_map_.erase(left, right);
 }
@@ -842,11 +842,6 @@ void CodeMap::MoveCode(Address from, Address to) {
   code_map_.erase(range.first, it);
 }
 
-void CodeMap::DeleteCodeEntry(CodeEntry* entry) {
-  entry->ReleaseStrings(function_and_resource_names_);
-  delete entry;
-}
-
 void CodeMap::Print() {
   for (const auto& pair : code_map_) {
     base::OS::Print("%p %5d %s\n", reinterpret_cast<void*>(pair.first),

src/profiler/profile-generator.h

@@ -76,6 +76,7 @@ class CodeEntry {
     // No alive handles should be associated with the CodeEntry at time of
     // destruction.
     DCHECK(!heap_object_location_);
+    DCHECK_EQ(ref_count_, 0UL);
   }
 
   const char* name() const { return name_; }
@@ -107,8 +108,6 @@ class CodeEntry {
     rare_data_->deopt_reason_ = kNoDeoptReason;
     rare_data_->deopt_id_ = kNoDeoptimizationId;
   }
-  void mark_used() { bit_field_ = UsedField::update(bit_field_, true); }
-  bool used() const { return UsedField::decode(bit_field_); }
 
   const char* code_type_string() const {
     switch (CodeTypeField::decode(bit_field_)) {
@@ -137,6 +136,10 @@ class CodeEntry {
     return SharedCrossOriginField::decode(bit_field_);
   }
 
+  // Returns whether or not the lifetime of this CodeEntry is reference
+  // counted, and managed by a CodeMap.
+  bool is_ref_counted() const { return RefCountedField::decode(bit_field_); }
+
   uint32_t GetHash() const;
   bool IsSameFunctionAs(const CodeEntry* entry) const;
 
@@ -193,6 +196,8 @@ class CodeEntry {
   void print() const;
 
  private:
+  friend class CodeEntryStorage;
+
   struct RareData {
     const char* deopt_reason_ = kNoDeoptReason;
     const char* bailout_reason_ = kEmptyBailoutReason;
@@ -205,17 +210,35 @@ class CodeEntry {
 
   RareData* EnsureRareData();
 
+  void mark_ref_counted() {
+    bit_field_ = RefCountedField::update(bit_field_, true);
+    ref_count_ = 1;
+  }
+
+  size_t AddRef() {
+    DCHECK(is_ref_counted());
+    DCHECK_LT(ref_count_, std::numeric_limits<size_t>::max());
+    ref_count_++;
+    return ref_count_;
+  }
+
+  size_t DecRef() {
+    DCHECK(is_ref_counted());
+    DCHECK_GT(ref_count_, 0UL);
+    ref_count_--;
+    return ref_count_;
+  }
+
   using TagField = base::BitField<CodeEventListener::LogEventsAndTags, 0, 8>;
   using BuiltinField = base::BitField<Builtin, 8, 20>;
   static_assert(Builtins::kBuiltinCount <= BuiltinField::kNumValues,
                 "builtin_count exceeds size of bitfield");
-  using CodeTypeField = base::BitField<CodeType, 28, 2>;
-  using UsedField = base::BitField<bool, 30, 1>;
+  using RefCountedField = base::BitField<bool, 28, 1>;
+  using CodeTypeField = base::BitField<CodeType, 29, 2>;
   using SharedCrossOriginField = base::BitField<bool, 31, 1>;
 
-  // Atomic because Used is written from the profiler thread while CodeType is
-  // read from the main thread.
-  std::atomic<std::uint32_t> bit_field_;
+  std::uint32_t bit_field_;
+  std::atomic<std::size_t> ref_count_ = {0};
   const char* name_;
   const char* resource_name_;
   int line_number_;
@@ -266,6 +289,7 @@ class V8_EXPORT_PRIVATE ProfileNode {
  public:
   inline ProfileNode(ProfileTree* tree, CodeEntry* entry, ProfileNode* parent,
                      int line_number = 0);
+  ~ProfileNode();
   ProfileNode(const ProfileNode&) = delete;
   ProfileNode& operator=(const ProfileNode&) = delete;
 
@@ -329,9 +353,11 @@ class V8_EXPORT_PRIVATE ProfileNode {
   std::vector<CpuProfileDeoptInfo> deopt_infos_;
 };
 
+class CodeEntryStorage;
+
 class V8_EXPORT_PRIVATE ProfileTree {
  public:
-  explicit ProfileTree(Isolate* isolate);
+  explicit ProfileTree(Isolate* isolate, CodeEntryStorage* storage = nullptr);
   ~ProfileTree();
   ProfileTree(const ProfileTree&) = delete;
   ProfileTree& operator=(const ProfileTree&) = delete;
@@ -360,6 +386,8 @@ class V8_EXPORT_PRIVATE ProfileTree {
     return std::move(pending_nodes_);
   }
 
+  CodeEntryStorage* code_entries() { return code_entries_; }
+
  private:
   template <typename Callback>
   void TraverseDepthFirst(Callback* callback);
@@ -369,6 +397,7 @@ class V8_EXPORT_PRIVATE ProfileTree {
   unsigned next_node_id_;
   ProfileNode* root_;
   Isolate* isolate_;
+  CodeEntryStorage* code_entries_;
 };
 
 class CpuProfiler;
@@ -450,13 +479,13 @@ class CpuProfileMaxSamplesCallbackTask : public v8::Task {
 
 class V8_EXPORT_PRIVATE CodeMap {
  public:
-  // Creates a new CodeMap with an associated StringsStorage to store the
-  // strings of CodeEntry objects within.
-  explicit CodeMap(StringsStorage& function_and_resource_names);
+  explicit CodeMap(CodeEntryStorage& storage);
   ~CodeMap();
   CodeMap(const CodeMap&) = delete;
   CodeMap& operator=(const CodeMap&) = delete;
 
+  // Adds the given CodeEntry to the CodeMap. The CodeMap takes ownership of
+  // the CodeEntry.
   void AddCode(Address addr, CodeEntry* entry, unsigned size);
   void MoveCode(Address from, Address to);
   // Attempts to remove the given CodeEntry from the CodeMap.
@@ -467,6 +496,8 @@ class V8_EXPORT_PRIVATE CodeMap {
   void Print();
   size_t size() const { return code_map_.size(); }
 
+  CodeEntryStorage& code_entries() { return code_entries_; }
+
   void Clear();
 
  private:
@@ -475,12 +506,28 @@ class V8_EXPORT_PRIVATE CodeMap {
     unsigned size;
   };
 
-  void DeleteCodeEntry(CodeEntry*);
-
   std::multimap<Address, CodeEntryMapInfo> code_map_;
-  std::deque<CodeEntry*> used_entries_;  // Entries that are no longer in the
-                                         // map, but used by a profile.
-  StringsStorage& function_and_resource_names_;
+  CodeEntryStorage& code_entries_;
+};
+
+// Manages the lifetime of CodeEntry objects, and stores shared resources
+// between them.
+class V8_EXPORT_PRIVATE CodeEntryStorage {
+ public:
+  template <typename... Args>
+  static CodeEntry* Create(Args&&... args) {
+    CodeEntry* const entry = new CodeEntry(std::forward<Args>(args)...);
+    entry->mark_ref_counted();
+    return entry;
+  }
+
+  void AddRef(CodeEntry*);
+  void DecRef(CodeEntry*);
+
+  StringsStorage& strings() { return function_and_resource_names_; }
+
+ private:
+  StringsStorage function_and_resource_names_;
 };
 
 class V8_EXPORT_PRIVATE CpuProfilesCollection {

src/profiler/profiler-listener.cc

@@ -29,12 +29,12 @@ namespace internal {
 
 ProfilerListener::ProfilerListener(Isolate* isolate,
                                    CodeEventObserver* observer,
-                                   StringsStorage& function_and_resource_names,
+                                   CodeEntryStorage& code_entry_storage,
                                    WeakCodeRegistry& weak_code_registry,
                                    CpuProfilingNamingMode naming_mode)
     : isolate_(isolate),
       observer_(observer),
-      function_and_resource_names_(function_and_resource_names),
+      code_entries_(code_entry_storage),
       weak_code_registry_(weak_code_registry),
       naming_mode_(naming_mode) {}
 
@@ -46,9 +46,10 @@ void ProfilerListener::CodeCreateEvent(LogEventsAndTags tag,
   CodeEventsContainer evt_rec(CodeEventRecord::CODE_CREATION);
   CodeCreateEventRecord* rec = &evt_rec.CodeCreateEventRecord_;
   rec->instruction_start = code->InstructionStart();
-  rec->entry = new CodeEntry(tag, GetName(name), CodeEntry::kEmptyResourceName,
-                             CpuProfileNode::kNoLineNumberInfo,
-                             CpuProfileNode::kNoColumnNumberInfo, nullptr);
+  rec->entry =
+      code_entries_.Create(tag, GetName(name), CodeEntry::kEmptyResourceName,
+                           CpuProfileNode::kNoLineNumberInfo,
+                           CpuProfileNode::kNoColumnNumberInfo, nullptr);
   rec->instruction_size = code->InstructionSize();
   weak_code_registry_.Track(rec->entry, code);
   DispatchCodeEvent(evt_rec);
@@ -60,9 +61,10 @@ void ProfilerListener::CodeCreateEvent(LogEventsAndTags tag,
   CodeEventsContainer evt_rec(CodeEventRecord::CODE_CREATION);
   CodeCreateEventRecord* rec = &evt_rec.CodeCreateEventRecord_;
   rec->instruction_start = code->InstructionStart();
-  rec->entry = new CodeEntry(tag, GetName(*name), CodeEntry::kEmptyResourceName,
-                             CpuProfileNode::kNoLineNumberInfo,
-                             CpuProfileNode::kNoColumnNumberInfo, nullptr);
+  rec->entry =
+      code_entries_.Create(tag, GetName(*name), CodeEntry::kEmptyResourceName,
+                           CpuProfileNode::kNoLineNumberInfo,
+                           CpuProfileNode::kNoColumnNumberInfo, nullptr);
   rec->instruction_size = code->InstructionSize();
   weak_code_registry_.Track(rec->entry, code);
   DispatchCodeEvent(evt_rec);
@@ -75,10 +77,11 @@ void ProfilerListener::CodeCreateEvent(LogEventsAndTags tag,
   CodeEventsContainer evt_rec(CodeEventRecord::CODE_CREATION);
   CodeCreateEventRecord* rec = &evt_rec.CodeCreateEventRecord_;
   rec->instruction_start = code->InstructionStart();
-  rec->entry = new CodeEntry(tag, GetName(shared->DebugNameCStr().get()),
-                             GetName(InferScriptName(*script_name, *shared)),
-                             CpuProfileNode::kNoLineNumberInfo,
-                             CpuProfileNode::kNoColumnNumberInfo, nullptr);
+  rec->entry =
+      code_entries_.Create(tag, GetName(shared->DebugNameCStr().get()),
+                           GetName(InferScriptName(*script_name, *shared)),
+                           CpuProfileNode::kNoLineNumberInfo,
+                           CpuProfileNode::kNoColumnNumberInfo, nullptr);
   DCHECK_IMPLIES(code->IsCode(), code->kind() == CodeKind::BASELINE);
   rec->entry->FillFunctionInfo(*shared);
   rec->instruction_size = code->InstructionSize();
@@ -91,10 +94,10 @@ namespace {
 CodeEntry* GetOrInsertCachedEntry(
     std::unordered_set<std::unique_ptr<CodeEntry>, CodeEntry::Hasher,
                        CodeEntry::Equals>* entries,
-    std::unique_ptr<CodeEntry> search_value, StringsStorage& strings) {
+    std::unique_ptr<CodeEntry> search_value, CodeEntryStorage& storage) {
   auto it = entries->find(search_value);
   if (it != entries->end()) {
-    search_value->ReleaseStrings(strings);
+    search_value->ReleaseStrings(storage.strings());
     return it->get();
   }
   CodeEntry* ret = search_value.get();
@@ -204,8 +207,7 @@ void ProfilerListener::CodeCreateEvent(LogEventsAndTags tag,
           // Create a canonical CodeEntry for each inlined frame and then re-use
           // them for subsequent inline stacks to avoid a lot of duplication.
           CodeEntry* cached_entry = GetOrInsertCachedEntry(
-              &cached_inline_entries, std::move(inline_entry),
-              function_and_resource_names_);
+              &cached_inline_entries, std::move(inline_entry), code_entries_);
 
           inline_stack.push_back({cached_entry, line_number});
         }
@@ -214,10 +216,10 @@ void ProfilerListener::CodeCreateEvent(LogEventsAndTags tag,
       }
     }
   }
-  rec->entry =
-      new CodeEntry(tag, GetFunctionName(*shared),
-                    GetName(InferScriptName(*script_name, *shared)), line,
-                    column, std::move(line_table), is_shared_cross_origin);
+  rec->entry = code_entries_.Create(
+      tag, GetFunctionName(*shared),
+      GetName(InferScriptName(*script_name, *shared)), line, column,
+      std::move(line_table), is_shared_cross_origin);
   if (!inline_stacks.empty()) {
     rec->entry->SetInlineStacks(std::move(cached_inline_entries),
                                 std::move(inline_stacks));
@@ -238,9 +240,9 @@ void ProfilerListener::CodeCreateEvent(LogEventsAndTags tag,
   CodeEventsContainer evt_rec(CodeEventRecord::CODE_CREATION);
   CodeCreateEventRecord* rec = &evt_rec.CodeCreateEventRecord_;
   rec->instruction_start = code->instruction_start();
-  rec->entry =
-      new CodeEntry(tag, GetName(name), GetName(source_url), 1, code_offset + 1,
-                    nullptr, true, CodeEntry::CodeType::WASM);
+  rec->entry = code_entries_.Create(tag, GetName(name), GetName(source_url), 1,
+                                    code_offset + 1, nullptr, true,
+                                    CodeEntry::CodeType::WASM);
   rec->entry->set_script_id(script_id);
   rec->entry->set_position(code_offset);
   rec->instruction_size = code->instructions().length();
@@ -252,7 +254,8 @@ void ProfilerListener::CallbackEvent(Handle<Name> name, Address entry_point) {
   CodeEventsContainer evt_rec(CodeEventRecord::CODE_CREATION);
   CodeCreateEventRecord* rec = &evt_rec.CodeCreateEventRecord_;
   rec->instruction_start = entry_point;
-  rec->entry = new CodeEntry(CodeEventListener::CALLBACK_TAG, GetName(*name));
+  rec->entry =
+      code_entries_.Create(CodeEventListener::CALLBACK_TAG, GetName(*name));
   rec->instruction_size = 1;
   DispatchCodeEvent(evt_rec);
 }
@@ -262,8 +265,8 @@ void ProfilerListener::GetterCallbackEvent(Handle<Name> name,
   CodeEventsContainer evt_rec(CodeEventRecord::CODE_CREATION);
   CodeCreateEventRecord* rec = &evt_rec.CodeCreateEventRecord_;
   rec->instruction_start = entry_point;
-  rec->entry = new CodeEntry(CodeEventListener::CALLBACK_TAG,
-                             GetConsName("get ", *name));
+  rec->entry = code_entries_.Create(CodeEventListener::CALLBACK_TAG,
+                                    GetConsName("get ", *name));
   rec->instruction_size = 1;
   DispatchCodeEvent(evt_rec);
 }
@@ -273,8 +276,8 @@ void ProfilerListener::SetterCallbackEvent(Handle<Name> name,
   CodeEventsContainer evt_rec(CodeEventRecord::CODE_CREATION);
   CodeCreateEventRecord* rec = &evt_rec.CodeCreateEventRecord_;
   rec->instruction_start = entry_point;
-  rec->entry = new CodeEntry(CodeEventListener::CALLBACK_TAG,
-                             GetConsName("set ", *name));
+  rec->entry = code_entries_.Create(CodeEventListener::CALLBACK_TAG,
+                                    GetConsName("set ", *name));
   rec->instruction_size = 1;
   DispatchCodeEvent(evt_rec);
 }
@@ -284,7 +287,7 @@ void ProfilerListener::RegExpCodeCreateEvent(Handle<AbstractCode> code,
   CodeEventsContainer evt_rec(CodeEventRecord::CODE_CREATION);
   CodeCreateEventRecord* rec = &evt_rec.CodeCreateEventRecord_;
   rec->instruction_start = code->InstructionStart();
-  rec->entry = new CodeEntry(
+  rec->entry = code_entries_.Create(
       CodeEventListener::REG_EXP_TAG, GetConsName("RegExp: ", *source),
       CodeEntry::kEmptyResourceName, CpuProfileNode::kNoLineNumberInfo,
       CpuProfileNode::kNoColumnNumberInfo, nullptr);

src/profiler/profiler-listener.h

@@ -29,7 +29,7 @@ class V8_EXPORT_PRIVATE ProfilerListener : public CodeEventListener,
                                            public WeakCodeRegistry::Listener {
  public:
   ProfilerListener(Isolate*, CodeEventObserver*,
-                   StringsStorage& function_and_resource_names,
+                   CodeEntryStorage& code_entry_storage,
                    WeakCodeRegistry& weak_code_registry,
                    CpuProfilingNamingMode mode = kDebugNaming);
   ~ProfilerListener() override;
@@ -76,17 +76,17 @@ class V8_EXPORT_PRIVATE ProfilerListener : public CodeEventListener,
   void CodeSweepEvent();
 
   const char* GetName(Name name) {
-    return function_and_resource_names_.GetName(name);
+    return code_entries_.strings().GetName(name);
   }
   const char* GetName(int args_count) {
-    return function_and_resource_names_.GetName(args_count);
+    return code_entries_.strings().GetName(args_count);
   }
   const char* GetName(const char* name) {
-    return function_and_resource_names_.GetCopy(name);
+    return code_entries_.strings().GetCopy(name);
   }
   const char* GetName(Vector<const char> name);
   const char* GetConsName(const char* prefix, Name name) {
-    return function_and_resource_names_.GetConsName(prefix, name);
+    return code_entries_.strings().GetConsName(prefix, name);
   }
 
   void set_observer(CodeEventObserver* observer) { observer_ = observer; }
@@ -102,7 +102,7 @@ class V8_EXPORT_PRIVATE ProfilerListener : public CodeEventListener,
 
   Isolate* isolate_;
   CodeEventObserver* observer_;
-  StringsStorage& function_and_resource_names_;
+  CodeEntryStorage& code_entries_;
   WeakCodeRegistry& weak_code_registry_;
   const CpuProfilingNamingMode naming_mode_;
 };

src/profiler/symbolizer.cc

@@ -16,9 +16,7 @@ Symbolizer::Symbolizer(CodeMap* code_map) : code_map_(code_map) {}
 
 CodeEntry* Symbolizer::FindEntry(Address address,
                                  Address* out_instruction_start) {
-  CodeEntry* entry = code_map_->FindEntry(address, out_instruction_start);
-  if (entry) entry->mark_used();
-  return entry;
+  return code_map_->FindEntry(address, out_instruction_start);
 }
 
 namespace {

test/cctest/test-cpu-profiler.cc

@@ -88,8 +88,9 @@ static const char* reason(const i::DeoptimizeReason reason) {
 
 TEST(StartStop) {
   i::Isolate* isolate = CcTest::i_isolate();
+  CodeEntryStorage storage;
   CpuProfilesCollection profiles(isolate);
-  ProfilerCodeObserver code_observer(isolate);
+  ProfilerCodeObserver code_observer(isolate, storage);
   Symbolizer symbolizer(code_observer.code_map());
   std::unique_ptr<ProfilerEventsProcessor> processor(
       new SamplingEventsProcessor(
@@ -171,15 +172,16 @@ TEST(CodeEvents) {
   i::Handle<i::AbstractCode> comment2_code(CreateCode(isolate, &env), isolate);
   i::Handle<i::AbstractCode> moved_code(CreateCode(isolate, &env), isolate);
 
+  CodeEntryStorage storage;
   CpuProfilesCollection* profiles = new CpuProfilesCollection(isolate);
-  ProfilerCodeObserver code_observer(isolate);
+  ProfilerCodeObserver code_observer(isolate, storage);
   Symbolizer* symbolizer = new Symbolizer(code_observer.code_map());
   ProfilerEventsProcessor* processor = new SamplingEventsProcessor(
       isolate, symbolizer, &code_observer, profiles,
       v8::base::TimeDelta::FromMicroseconds(100), true);
   CHECK(processor->Start());
   ProfilerListener profiler_listener(isolate, processor,
-                                     *code_observer.strings(),
+                                     *code_observer.code_entries(),
                                      *code_observer.weak_code_registry());
   isolate->logger()->AddCodeEventListener(&profiler_listener);
 
@@ -234,8 +236,10 @@ TEST(TickEvents) {
   i::Handle<i::AbstractCode> frame2_code(CreateCode(isolate, &env), isolate);
   i::Handle<i::AbstractCode> frame3_code(CreateCode(isolate, &env), isolate);
 
+  CodeEntryStorage storage;
   CpuProfilesCollection* profiles = new CpuProfilesCollection(isolate);
-  ProfilerCodeObserver* code_observer = new ProfilerCodeObserver(isolate);
+  ProfilerCodeObserver* code_observer =
+      new ProfilerCodeObserver(isolate, storage);
   Symbolizer* symbolizer = new Symbolizer(code_observer->code_map());
   ProfilerEventsProcessor* processor = new SamplingEventsProcessor(
       CcTest::i_isolate(), symbolizer, code_observer, profiles,
@@ -245,7 +249,7 @@ TEST(TickEvents) {
   profiles->StartProfiling("");
   CHECK(processor->Start());
   ProfilerListener profiler_listener(isolate, processor,
-                                     *code_observer->strings(),
+                                     *code_observer->code_entries(),
                                      *code_observer->weak_code_registry());
   isolate->logger()->AddCodeEventListener(&profiler_listener);
 
@@ -396,8 +400,10 @@ TEST(Issue1398) {
 
   i::Handle<i::AbstractCode> code(CreateCode(isolate, &env), isolate);
 
+  CodeEntryStorage storage;
   CpuProfilesCollection* profiles = new CpuProfilesCollection(isolate);
-  ProfilerCodeObserver* code_observer = new ProfilerCodeObserver(isolate);
+  ProfilerCodeObserver* code_observer =
+      new ProfilerCodeObserver(isolate, storage);
   Symbolizer* symbolizer = new Symbolizer(code_observer->code_map());
   ProfilerEventsProcessor* processor = new SamplingEventsProcessor(
       CcTest::i_isolate(), symbolizer, code_observer, profiles,
@@ -407,7 +413,7 @@ TEST(Issue1398) {
   profiles->StartProfiling("");
   CHECK(processor->Start());
   ProfilerListener profiler_listener(isolate, processor,
-                                     *code_observer->strings(),
+                                     *code_observer->code_entries(),
                                      *code_observer->weak_code_registry());
 
   profiler_listener.CodeCreateEvent(i::Logger::BUILTIN_TAG, code, "bbb");
@@ -1262,8 +1268,10 @@ static void TickLines(bool optimize) {
   i::Address code_address = code->raw_instruction_start();
   CHECK_NE(code_address, kNullAddress);
 
+  CodeEntryStorage storage;
   CpuProfilesCollection* profiles = new CpuProfilesCollection(isolate);
-  ProfilerCodeObserver* code_observer = new ProfilerCodeObserver(isolate);
+  ProfilerCodeObserver* code_observer =
+      new ProfilerCodeObserver(isolate, storage);
   Symbolizer* symbolizer = new Symbolizer(code_observer->code_map());
   ProfilerEventsProcessor* processor = new SamplingEventsProcessor(
       CcTest::i_isolate(), symbolizer, code_observer, profiles,
@@ -1278,7 +1286,7 @@ static void TickLines(bool optimize) {
   isolate->logger()->LogCompiledFunctions();
   CHECK(processor->Start());
   ProfilerListener profiler_listener(isolate, processor,
-                                     *code_observer->strings(),
+                                     *code_observer->code_entries(),
                                      *code_observer->weak_code_registry());
 
   // Enqueue code creation events.
@@ -3474,8 +3482,9 @@ TEST(MaxSimultaneousProfiles) {
 
 TEST(LowPrecisionSamplingStartStopInternal) {
   i::Isolate* isolate = CcTest::i_isolate();
+  CodeEntryStorage storage;
   CpuProfilesCollection profiles(isolate);
-  ProfilerCodeObserver code_observer(isolate);
+  ProfilerCodeObserver code_observer(isolate, storage);
   Symbolizer symbolizer(code_observer.code_map());
   std::unique_ptr<ProfilerEventsProcessor> processor(
       new SamplingEventsProcessor(
@@ -3600,8 +3609,10 @@ TEST(ProflilerSubsampling) {
   i::Isolate* isolate = CcTest::i_isolate();
   i::HandleScope scope(isolate);
 
+  CodeEntryStorage storage;
   CpuProfilesCollection* profiles = new CpuProfilesCollection(isolate);
-  ProfilerCodeObserver* code_observer = new ProfilerCodeObserver(isolate);
+  ProfilerCodeObserver* code_observer =
+      new ProfilerCodeObserver(isolate, storage);
   Symbolizer* symbolizer = new Symbolizer(code_observer->code_map());
   ProfilerEventsProcessor* processor =
       new SamplingEventsProcessor(isolate, symbolizer, code_observer, profiles,
@@ -3644,8 +3655,10 @@ TEST(DynamicResampling) {
   i::Isolate* isolate = CcTest::i_isolate();
   i::HandleScope scope(isolate);
 
+  CodeEntryStorage storage;
   CpuProfilesCollection* profiles = new CpuProfilesCollection(isolate);
-  ProfilerCodeObserver* code_observer = new ProfilerCodeObserver(isolate);
+  ProfilerCodeObserver* code_observer =
+      new ProfilerCodeObserver(isolate, storage);
   Symbolizer* symbolizer = new Symbolizer(code_observer->code_map());
   ProfilerEventsProcessor* processor =
       new SamplingEventsProcessor(isolate, symbolizer, code_observer, profiles,
@@ -3705,8 +3718,10 @@ TEST(DynamicResamplingWithBaseInterval) {
   i::Isolate* isolate = CcTest::i_isolate();
   i::HandleScope scope(isolate);
 
+  CodeEntryStorage storage;
   CpuProfilesCollection* profiles = new CpuProfilesCollection(isolate);
-  ProfilerCodeObserver* code_observer = new ProfilerCodeObserver(isolate);
+  ProfilerCodeObserver* code_observer =
+      new ProfilerCodeObserver(isolate, storage);
   Symbolizer* symbolizer = new Symbolizer(code_observer->code_map());
   ProfilerEventsProcessor* processor =
       new SamplingEventsProcessor(isolate, symbolizer, code_observer, profiles,

test/cctest/test-profile-generator.cc

@@ -311,12 +311,12 @@ static inline i::Address ToAddress(int n) { return static_cast<i::Address>(n); }
 static inline void* ToPointer(int n) { return reinterpret_cast<void*>(n); }
 
 TEST(CodeMapAddCode) {
-  StringsStorage strings;
-  CodeMap code_map(strings);
-  CodeEntry* entry1 = new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "aaa");
-  CodeEntry* entry2 = new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "bbb");
-  CodeEntry* entry3 = new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "ccc");
-  CodeEntry* entry4 = new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "ddd");
+  CodeEntryStorage storage;
+  CodeMap code_map(storage);
+  CodeEntry* entry1 = storage.Create(i::CodeEventListener::FUNCTION_TAG, "aaa");
+  CodeEntry* entry2 = storage.Create(i::CodeEventListener::FUNCTION_TAG, "bbb");
+  CodeEntry* entry3 = storage.Create(i::CodeEventListener::FUNCTION_TAG, "ccc");
+  CodeEntry* entry4 = storage.Create(i::CodeEventListener::FUNCTION_TAG, "ddd");
   code_map.AddCode(ToAddress(0x1500), entry1, 0x200);
   code_map.AddCode(ToAddress(0x1700), entry2, 0x100);
   code_map.AddCode(ToAddress(0x1900), entry3, 0x50);
@@ -341,10 +341,10 @@ TEST(CodeMapAddCode) {
 }
 
 TEST(CodeMapMoveAndDeleteCode) {
-  StringsStorage strings;
-  CodeMap code_map(strings);
-  CodeEntry* entry1 = new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "aaa");
-  CodeEntry* entry2 = new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "bbb");
+  CodeEntryStorage storage;
+  CodeMap code_map(storage);
+  CodeEntry* entry1 = storage.Create(i::CodeEventListener::FUNCTION_TAG, "aaa");
+  CodeEntry* entry2 = storage.Create(i::CodeEventListener::FUNCTION_TAG, "bbb");
   code_map.AddCode(ToAddress(0x1500), entry1, 0x200);
   code_map.AddCode(ToAddress(0x1700), entry2, 0x100);
   CHECK_EQ(entry1, code_map.FindEntry(ToAddress(0x1500)));
@@ -355,10 +355,10 @@ TEST(CodeMapMoveAndDeleteCode) {
 }
 
 TEST(CodeMapClear) {
-  StringsStorage strings;
-  CodeMap code_map(strings);
-  CodeEntry* entry1 = new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "aaa");
-  CodeEntry* entry2 = new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "bbb");
+  CodeEntryStorage storage;
+  CodeMap code_map(storage);
+  CodeEntry* entry1 = storage.Create(i::CodeEventListener::FUNCTION_TAG, "aaa");
+  CodeEntry* entry2 = storage.Create(i::CodeEventListener::FUNCTION_TAG, "bbb");
   code_map.AddCode(ToAddress(0x1500), entry1, 0x200);
   code_map.AddCode(ToAddress(0x1700), entry2, 0x100);
 
@@ -391,12 +391,12 @@ class TestSetup {
 
 TEST(SymbolizeTickSample) {
   TestSetup test_setup;
-  StringsStorage strings;
-  CodeMap code_map(strings);
+  CodeEntryStorage storage;
+  CodeMap code_map(storage);
   Symbolizer symbolizer(&code_map);
-  CodeEntry* entry1 = new CodeEntry(i::Logger::FUNCTION_TAG, "aaa");
-  CodeEntry* entry2 = new CodeEntry(i::Logger::FUNCTION_TAG, "bbb");
-  CodeEntry* entry3 = new CodeEntry(i::Logger::FUNCTION_TAG, "ccc");
+  CodeEntry* entry1 = storage.Create(i::Logger::FUNCTION_TAG, "aaa");
+  CodeEntry* entry2 = storage.Create(i::Logger::FUNCTION_TAG, "bbb");
+  CodeEntry* entry3 = storage.Create(i::Logger::FUNCTION_TAG, "ccc");
   symbolizer.code_map()->AddCode(ToAddress(0x1500), entry1, 0x200);
   symbolizer.code_map()->AddCode(ToAddress(0x1700), entry2, 0x100);
   symbolizer.code_map()->AddCode(ToAddress(0x1900), entry3, 0x50);
@@ -456,16 +456,16 @@ static void CheckNodeIds(const ProfileNode* node, unsigned* expectedId) {
 TEST(SampleIds) {
   TestSetup test_setup;
   i::Isolate* isolate = CcTest::i_isolate();
-  CpuProfilesCollection profiles(isolate);
   CpuProfiler profiler(isolate);
+  CpuProfilesCollection profiles(isolate);
   profiles.set_cpu_profiler(&profiler);
   profiles.StartProfiling("", {CpuProfilingMode::kLeafNodeLineNumbers});
-  StringsStorage strings;
-  CodeMap code_map(strings);
+  CodeEntryStorage storage;
+  CodeMap code_map(storage);
   Symbolizer symbolizer(&code_map);
-  CodeEntry* entry1 = new CodeEntry(i::Logger::FUNCTION_TAG, "aaa");
-  CodeEntry* entry2 = new CodeEntry(i::Logger::FUNCTION_TAG, "bbb");
-  CodeEntry* entry3 = new CodeEntry(i::Logger::FUNCTION_TAG, "ccc");
+  CodeEntry* entry1 = storage.Create(i::Logger::FUNCTION_TAG, "aaa");
+  CodeEntry* entry2 = storage.Create(i::Logger::FUNCTION_TAG, "bbb");
+  CodeEntry* entry3 = storage.Create(i::Logger::FUNCTION_TAG, "ccc");
   symbolizer.code_map()->AddCode(ToAddress(0x1500), entry1, 0x200);
   symbolizer.code_map()->AddCode(ToAddress(0x1700), entry2, 0x100);
   symbolizer.code_map()->AddCode(ToAddress(0x1900), entry3, 0x50);
@@ -592,8 +592,8 @@ TEST(MaxSamplesCallback) {
                            MaybeLocal<v8::Context>()},
                           std::move(impl));
 
-  StringsStorage strings;
-  CodeMap code_map(strings);
+  CodeEntryStorage storage;
+  CodeMap code_map(storage);
   Symbolizer symbolizer(&code_map);
   TickSample sample1;
   sample1.timestamp = v8::base::TimeTicks::HighResolutionNow();
@@ -633,14 +633,14 @@ TEST(MaxSamplesCallback) {
 TEST(NoSamples) {
   TestSetup test_setup;
   i::Isolate* isolate = CcTest::i_isolate();
-  CpuProfilesCollection profiles(isolate);
   CpuProfiler profiler(isolate);
+  CpuProfilesCollection profiles(isolate);
   profiles.set_cpu_profiler(&profiler);
   profiles.StartProfiling("");
-  StringsStorage strings;
-  CodeMap code_map(strings);
+  CodeEntryStorage storage;
+  CodeMap code_map(storage);
   Symbolizer symbolizer(&code_map);
-  CodeEntry* entry1 = new CodeEntry(i::Logger::FUNCTION_TAG, "aaa");
+  CodeEntry* entry1 = storage.Create(i::Logger::FUNCTION_TAG, "aaa");
   symbolizer.code_map()->AddCode(ToAddress(0x1500), entry1, 0x200);
 
   // We are building the following calls tree:
@@ -959,10 +959,10 @@ TEST(NodeSourceTypes) {
 }
 
 TEST(CodeMapRemoveCode) {
-  StringsStorage strings;
-  CodeMap code_map(strings);
+  CodeEntryStorage storage;
+  CodeMap code_map(storage);
 
-  CodeEntry* entry = new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "aaa");
+  CodeEntry* entry = storage.Create(i::CodeEventListener::FUNCTION_TAG, "aaa");
   code_map.AddCode(ToAddress(0x1000), entry, 0x100);
   CHECK(code_map.RemoveCode(entry));
   CHECK(!code_map.FindEntry(ToAddress(0x1000)));
@@ -970,9 +970,9 @@ TEST(CodeMapRemoveCode) {
   // Test that when two entries share the same address, we remove only the
   // entry that we desired to.
   CodeEntry* colliding_entry1 =
-      new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "aaa");
+      storage.Create(i::CodeEventListener::FUNCTION_TAG, "aaa");
   CodeEntry* colliding_entry2 =
-      new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "aaa");
+      storage.Create(i::CodeEventListener::FUNCTION_TAG, "aaa");
   code_map.AddCode(ToAddress(0x1000), colliding_entry1, 0x100);
   code_map.AddCode(ToAddress(0x1000), colliding_entry2, 0x100);
 
@@ -984,14 +984,14 @@ TEST(CodeMapRemoveCode) {
 }
 
 TEST(CodeMapMoveOverlappingCode) {
-  StringsStorage strings;
-  CodeMap code_map(strings);
+  CodeEntryStorage storage;
+  CodeMap code_map(storage);
   CodeEntry* colliding_entry1 =
-      new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "aaa");
+      storage.Create(i::CodeEventListener::FUNCTION_TAG, "aaa");
   CodeEntry* colliding_entry2 =
-      new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "bbb");
+      storage.Create(i::CodeEventListener::FUNCTION_TAG, "bbb");
   CodeEntry* after_entry =
-      new CodeEntry(i::CodeEventListener::FUNCTION_TAG, "ccc");
+      storage.Create(i::CodeEventListener::FUNCTION_TAG, "ccc");
 
   code_map.AddCode(ToAddress(0x1400), colliding_entry1, 0x200);
   code_map.AddCode(ToAddress(0x1400), colliding_entry2, 0x200);