[compiler] Introduce ReusableUnoptimizedCompileState

Introduce a ReusableUnoptimizedCompileState class, passed to ParseInfo,
which stores a couple of pointers and most importantly the Zone and
AstValueFactory of the parse. This allows the Zone and AstValueFactory
to be reused across multiple parses, rather than re-initialising
per-Parse.

With this, we can amend the LazyCompileDispatcher to initialise one
LocalIsolate, Zone and AstValueFactory per background thread loop,
rather than one per compile task, which allows us to reduce per-task
costs and re-use the AstValueFactory's string table and previous String
internalizations.

Change-Id: Ia0e29c4e31fbe29af57674ebb10916865d38b2ce
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3313106Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78289}

src/ast/ast-value-factory.cc

@@ -367,8 +367,6 @@ AstConsString* AstValueFactory::NewConsString(const AstRawString* str1,
 
 template <typename IsolateT>
 void AstValueFactory::Internalize(IsolateT* isolate) {
-  if (!zone_) return;
-
   // Strings need to be internalized before values, because values refer to
   // strings.
   for (AstRawString* current = strings_; current != nullptr;) {
@@ -378,7 +376,6 @@ void AstValueFactory::Internalize(IsolateT* isolate) {
   }
 
   ResetStrings();
-  zone_ = nullptr;
 }
 template EXPORT_TEMPLATE_DEFINE(
     V8_EXPORT_PRIVATE) void AstValueFactory::Internalize(Isolate* isolate);

src/codegen/compiler.h

@@ -511,12 +511,13 @@ class V8_EXPORT_PRIVATE BackgroundCompileTask {
   // Compiler::FinalizeBackgroundCompileTask.
   BackgroundCompileTask(
       Isolate* isolate, Handle<SharedFunctionInfo> shared_info,
-      const UnoptimizedCompileState* compile_state,
       std::unique_ptr<Utf16CharacterStream> character_stream,
       WorkerThreadRuntimeCallStats* worker_thread_runtime_stats,
       TimedHistogram* timer, int max_stack_size);
 
   void Run();
+  void Run(LocalIsolate* isolate,
+           ReusableUnoptimizedCompileState* reusable_state);
 
   MaybeHandle<SharedFunctionInfo> FinalizeScript(
       Isolate* isolate, Handle<String> source,

src/codegen/unoptimized-compilation-info.cc

@@ -19,7 +19,7 @@ UnoptimizedCompilationInfo::UnoptimizedCompilationInfo(Zone* zone,
                                                        ParseInfo* parse_info,
                                                        FunctionLiteral* literal)
     : flags_(parse_info->flags()),
-      state_(parse_info->state()),
+      dispatcher_(parse_info->dispatcher()),
       character_stream_(parse_info->character_stream()),
       feedback_vector_spec_(zone) {
   // NOTE: The parse_info passed here represents the global information gathered

src/codegen/unoptimized-compilation-info.h

@@ -35,7 +35,7 @@ class V8_EXPORT_PRIVATE UnoptimizedCompilationInfo final {
                              FunctionLiteral* literal);
 
   const UnoptimizedCompileFlags& flags() const { return flags_; }
-  const UnoptimizedCompileState* state() const { return state_; }
+  LazyCompileDispatcher* dispatcher() { return dispatcher_; }
   const Utf16CharacterStream* character_stream() const {
     return character_stream_;
   }
@@ -90,8 +90,8 @@ class V8_EXPORT_PRIVATE UnoptimizedCompilationInfo final {
   // Compilation flags.
   const UnoptimizedCompileFlags flags_;
 
-  // Compilation state.
-  const UnoptimizedCompileState* state_;
+  // For dispatching eager compilation of lazily compiled functions.
+  LazyCompileDispatcher* dispatcher_;
   const Utf16CharacterStream* character_stream_;
 
   // The root AST node of the function literal being compiled.

src/compiler-dispatcher/lazy-compile-dispatcher.cc

@@ -13,11 +13,14 @@
 #include "src/codegen/compiler.h"
 #include "src/flags/flags.h"
 #include "src/handles/global-handles-inl.h"
+#include "src/heap/parked-scope.h"
 #include "src/logging/counters.h"
 #include "src/logging/runtime-call-stats-scope.h"
+#include "src/numbers/hash-seed-inl.h"
 #include "src/objects/objects-inl.h"
 #include "src/parsing/parse-info.h"
 #include "src/parsing/parser.h"
+#include "src/roots/roots.h"
 #include "src/tasks/cancelable-task.h"
 #include "src/tasks/task-utils.h"
 #include "src/zone/zone-list-inl.h"  // crbug.com/v8/8816
@@ -86,7 +89,6 @@ LazyCompileDispatcher::~LazyCompileDispatcher() {
 
 void LazyCompileDispatcher::Enqueue(
     LocalIsolate* isolate, Handle<SharedFunctionInfo> shared_info,
-    const UnoptimizedCompileState* compile_state,
     std::unique_ptr<Utf16CharacterStream> character_stream) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
                "V8.LazyCompilerDispatcherEnqueue");
@@ -94,7 +96,7 @@ void LazyCompileDispatcher::Enqueue(
 
   std::unique_ptr<Job> job =
       std::make_unique<Job>(std::make_unique<BackgroundCompileTask>(
-          isolate_, shared_info, compile_state, std::move(character_stream),
+          isolate_, shared_info, std::move(character_stream),
           worker_thread_runtime_call_stats_, background_compile_timer_,
           static_cast<int>(max_stack_size_)));
 
@@ -259,6 +261,17 @@ void LazyCompileDispatcher::ScheduleIdleTaskFromAnyThread(
 void LazyCompileDispatcher::DoBackgroundWork(JobDelegate* delegate) {
   TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("v8.compile"),
                "V8.LazyCompileDispatcherDoBackgroundWork");
+
+  WorkerThreadRuntimeCallStatsScope worker_thread_scope(
+      worker_thread_runtime_call_stats_);
+
+  LocalIsolate isolate(isolate_, ThreadKind::kBackground,
+                       worker_thread_scope.Get());
+  UnparkedScope unparked_scope(&isolate);
+  LocalHandleScope handle_scope(&isolate);
+
+  ReusableUnoptimizedCompileState reusable_state(&isolate);
+
   while (!delegate->ShouldYield()) {
     Job* job = nullptr;
     {
@@ -281,7 +294,7 @@ void LazyCompileDispatcher::DoBackgroundWork(JobDelegate* delegate) {
       PrintF("LazyCompileDispatcher: doing background work\n");
     }
 
-    job->task->Run();
+    job->task->Run(&isolate, &reusable_state);
 
     {
       base::MutexGuard lock(&mutex_);

src/compiler-dispatcher/lazy-compile-dispatcher.h

@@ -85,7 +85,6 @@ class V8_EXPORT_PRIVATE LazyCompileDispatcher {
   ~LazyCompileDispatcher();
 
   void Enqueue(LocalIsolate* isolate, Handle<SharedFunctionInfo> shared_info,
-               const UnoptimizedCompileState* compile_state,
                std::unique_ptr<Utf16CharacterStream> character_stream);
 
   // Returns true if there is a pending job registered for the given function.

src/d8/d8.cc

@@ -687,7 +687,8 @@ bool Shell::ExecuteString(Isolate* isolate, Local<String> source,
     i::Handle<i::String> str = Utils::OpenHandle(*(source));
 
     // Set up ParseInfo.
-    i::UnoptimizedCompileState compile_state(i_isolate);
+    i::UnoptimizedCompileState compile_state;
+    i::ReusableUnoptimizedCompileState reusable_state(i_isolate);
 
     i::UnoptimizedCompileFlags flags =
         i::UnoptimizedCompileFlags::ForToplevelCompile(
@@ -698,7 +699,7 @@ bool Shell::ExecuteString(Isolate* isolate, Local<String> source,
       flags.set_is_eager(true);
     }
 
-    i::ParseInfo parse_info(i_isolate, flags, &compile_state);
+    i::ParseInfo parse_info(i_isolate, flags, &compile_state, &reusable_state);
 
     i::Handle<i::Script> script = parse_info.CreateScript(
         i_isolate, str, i::kNullMaybeHandle, ScriptOriginOptions());

src/debug/debug-scopes.cc

@@ -272,9 +272,12 @@ void ScopeIterator::TryParseAndRetrieveScopes(ReparseStrategy strategy) {
            scope_info->scope_type() == FUNCTION_SCOPE);
   }
 
-  UnoptimizedCompileState compile_state(isolate_);
+  UnoptimizedCompileState compile_state;
 
-  info_ = std::make_unique<ParseInfo>(isolate_, flags, &compile_state);
+  reusable_compile_state_ =
+      std::make_unique<ReusableUnoptimizedCompileState>(isolate_);
+  info_ = std::make_unique<ParseInfo>(isolate_, flags, &compile_state,
+                                      reusable_compile_state_.get());
 
   const bool parse_result =
       flags.is_toplevel()

src/debug/debug-scopes.h

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "src/debug/debug-frames.h"
+#include "src/parsing/parse-info.h"
 
 namespace v8 {
 namespace internal {
@@ -110,6 +111,7 @@ class ScopeIterator {
 
  private:
   Isolate* isolate_;
+  std::unique_ptr<ReusableUnoptimizedCompileState> reusable_compile_state_;
   std::unique_ptr<ParseInfo> info_;
   FrameInspector* const frame_inspector_ = nullptr;
   Handle<JSGeneratorObject> generator_;

src/debug/debug.cc

@@ -1545,10 +1545,11 @@ void FindBreakablePositions(Handle<DebugInfo> debug_info, int start_position,
 }
 
 bool CompileTopLevel(Isolate* isolate, Handle<Script> script) {
-  UnoptimizedCompileState compile_state(isolate);
+  UnoptimizedCompileState compile_state;
+  ReusableUnoptimizedCompileState reusable_state(isolate);
   UnoptimizedCompileFlags flags =
       UnoptimizedCompileFlags::ForScriptCompile(isolate, *script);
-  ParseInfo parse_info(isolate, flags, &compile_state);
+  ParseInfo parse_info(isolate, flags, &compile_state, &reusable_state);
   IsCompiledScope is_compiled_scope;
   const MaybeHandle<SharedFunctionInfo> maybe_result =
       Compiler::CompileToplevel(&parse_info, script, isolate,

src/debug/liveedit.cc

@@ -984,22 +984,25 @@ void LiveEdit::PatchScript(Isolate* isolate, Handle<Script> script,
     return;
   }
 
-  UnoptimizedCompileState compile_state(isolate);
+  ReusableUnoptimizedCompileState reusable_state(isolate);
+
+  UnoptimizedCompileState compile_state;
   UnoptimizedCompileFlags flags =
       UnoptimizedCompileFlags::ForScriptCompile(isolate, *script);
   flags.set_is_eager(true);
-  ParseInfo parse_info(isolate, flags, &compile_state);
+  ParseInfo parse_info(isolate, flags, &compile_state, &reusable_state);
   std::vector<FunctionLiteral*> literals;
   if (!ParseScript(isolate, script, &parse_info, false, &literals, result))
     return;
 
   Handle<Script> new_script = isolate->factory()->CloneScript(script);
   new_script->set_source(*new_source);
-  UnoptimizedCompileState new_compile_state(isolate);
+  UnoptimizedCompileState new_compile_state;
   UnoptimizedCompileFlags new_flags =
       UnoptimizedCompileFlags::ForScriptCompile(isolate, *new_script);
   new_flags.set_is_eager(true);
-  ParseInfo new_parse_info(isolate, new_flags, &new_compile_state);
+  ParseInfo new_parse_info(isolate, new_flags, &new_compile_state,
+                           &reusable_state);
   std::vector<FunctionLiteral*> new_literals;
   if (!ParseScript(isolate, new_script, &new_parse_info, true, &new_literals,
                    result)) {

src/execution/local-isolate.h

@@ -67,6 +67,17 @@ class V8_EXPORT_PRIVATE LocalIsolate final : private HiddenLocalFactory {
   base::SharedMutex* internalized_string_access() {
     return isolate_->internalized_string_access();
   }
+  const AstStringConstants* ast_string_constants() {
+    return isolate_->ast_string_constants();
+  }
+  LazyCompileDispatcher* lazy_compile_dispatcher() {
+    return isolate_->lazy_compile_dispatcher();
+  }
+  Logger* main_thread_logger() {
+    // TODO(leszeks): This is needed for logging in ParseInfo. Figure out a way
+    // to use the LocalLogger for this instead.
+    return isolate_->logger();
+  }
 
   v8::internal::LocalFactory* factory() {
     // Upcast to the privately inherited base-class using c-style casts to avoid

src/execution/messages.cc

@@ -779,8 +779,9 @@ Handle<String> RenderCallSite(Isolate* isolate, Handle<Object> object,
   if (ComputeLocation(isolate, location)) {
     UnoptimizedCompileFlags flags = UnoptimizedCompileFlags::ForFunctionCompile(
         isolate, *location->shared());
-    UnoptimizedCompileState compile_state(isolate);
-    ParseInfo info(isolate, flags, &compile_state);
+    UnoptimizedCompileState compile_state;
+    ReusableUnoptimizedCompileState reusable_state(isolate);
+    ParseInfo info(isolate, flags, &compile_state, &reusable_state);
     if (parsing::ParseAny(&info, location->shared(), isolate,
                           parsing::ReportStatisticsMode::kNo)) {
       info.ast_value_factory()->Internalize(isolate);
@@ -838,8 +839,9 @@ Object ErrorUtils::ThrowSpreadArgError(Isolate* isolate, MessageTemplate id,
   if (ComputeLocation(isolate, &location)) {
     UnoptimizedCompileFlags flags = UnoptimizedCompileFlags::ForFunctionCompile(
         isolate, *location.shared());
-    UnoptimizedCompileState compile_state(isolate);
-    ParseInfo info(isolate, flags, &compile_state);
+    UnoptimizedCompileState compile_state;
+    ReusableUnoptimizedCompileState reusable_state(isolate);
+    ParseInfo info(isolate, flags, &compile_state, &reusable_state);
     if (parsing::ParseAny(&info, location.shared(), isolate,
                           parsing::ReportStatisticsMode::kNo)) {
       info.ast_value_factory()->Internalize(isolate);
@@ -914,8 +916,9 @@ Object ErrorUtils::ThrowLoadFromNullOrUndefined(Isolate* isolate,
 
     UnoptimizedCompileFlags flags = UnoptimizedCompileFlags::ForFunctionCompile(
         isolate, *location.shared());
-    UnoptimizedCompileState compile_state(isolate);
-    ParseInfo info(isolate, flags, &compile_state);
+    UnoptimizedCompileState compile_state;
+    ReusableUnoptimizedCompileState reusable_state(isolate);
+    ParseInfo info(isolate, flags, &compile_state, &reusable_state);
     if (parsing::ParseAny(&info, location.shared(), isolate,
                           parsing::ReportStatisticsMode::kNo)) {
       info.ast_value_factory()->Internalize(isolate);

src/interpreter/bytecode-generator.cc

@@ -2528,7 +2528,7 @@ void BytecodeGenerator::AddToEagerLiteralsIfEager(FunctionLiteral* literal) {
         literal->ShouldEagerCompile(),
         info()->flags().post_parallel_compile_tasks_for_eager_toplevel());
     // There exists a lazy compile dispatcher.
-    DCHECK(info()->state()->dispatcher());
+    DCHECK(info()->dispatcher());
     // There exists a cloneable character stream.
     DCHECK(info()->character_stream()->can_be_cloned_for_parallel_access());
 
@@ -2542,9 +2542,8 @@ void BytecodeGenerator::AddToEagerLiteralsIfEager(FunctionLiteral* literal) {
              .ToHandle(&shared_info)) {
       shared_info =
           Compiler::GetSharedFunctionInfo(literal, script_, local_isolate_);
-      info()->state()->dispatcher()->Enqueue(
-          local_isolate_, shared_info, info()->state(),
-          info()->character_stream()->Clone());
+      info()->dispatcher()->Enqueue(local_isolate_, shared_info,
+                                    info()->character_stream()->Clone());
     }
   } else if (eager_inner_literals_ && literal->ShouldEagerCompile()) {
     DCHECK(!IsInEagerLiterals(literal, *eager_inner_literals_));

src/numbers/hash-seed-inl.h

@@ -17,9 +17,11 @@ namespace v8 {
 namespace internal {
 
 class Isolate;
+class LocalIsolate;
 class ReadOnlyRoots;
 
 inline uint64_t HashSeed(Isolate* isolate);
+inline uint64_t HashSeed(LocalIsolate* isolate);
 inline uint64_t HashSeed(ReadOnlyRoots roots);
 
 }  // namespace internal
@@ -36,6 +38,10 @@ inline uint64_t HashSeed(Isolate* isolate) {
   return HashSeed(ReadOnlyRoots(isolate));
 }
 
+inline uint64_t HashSeed(LocalIsolate* isolate) {
+  return HashSeed(ReadOnlyRoots(isolate));
+}
+
 inline uint64_t HashSeed(ReadOnlyRoots roots) {
   uint64_t seed;
   roots.hash_seed().copy_out(0, reinterpret_cast<byte*>(&seed), kInt64Size);

src/parsing/parse-info.cc

@@ -169,34 +169,44 @@ void UnoptimizedCompileFlags::SetFlagsForFunctionFromScript(Script script) {
                              script.IsUserJavaScript());
 }
 
-UnoptimizedCompileState::UnoptimizedCompileState(Isolate* isolate)
+ReusableUnoptimizedCompileState::ReusableUnoptimizedCompileState(
+    Isolate* isolate)
     : hash_seed_(HashSeed(isolate)),
       allocator_(isolate->allocator()),
-      ast_string_constants_(isolate->ast_string_constants()),
       logger_(isolate->logger()),
-      dispatcher_(isolate->lazy_compile_dispatcher()) {}
+      dispatcher_(isolate->lazy_compile_dispatcher()),
+      ast_string_constants_(isolate->ast_string_constants()),
+      zone_(allocator_, "unoptimized-compile-zone"),
+      ast_value_factory_(
+          new AstValueFactory(zone(), ast_string_constants(), hash_seed())) {}
 
-UnoptimizedCompileState::UnoptimizedCompileState(
-    const UnoptimizedCompileState& other) V8_NOEXCEPT
-    : hash_seed_(other.hash_seed()),
-      allocator_(other.allocator()),
-      ast_string_constants_(other.ast_string_constants()),
-      logger_(other.logger()),
-      dispatcher_(other.dispatcher()) {}
+ReusableUnoptimizedCompileState::ReusableUnoptimizedCompileState(
+    LocalIsolate* isolate)
+    : hash_seed_(HashSeed(isolate)),
+      allocator_(isolate->allocator()),
+      logger_(isolate->main_thread_logger()),
+      dispatcher_(isolate->lazy_compile_dispatcher()),
+      ast_string_constants_(isolate->ast_string_constants()),
+      zone_(allocator_, "unoptimized-compile-zone"),
+      ast_value_factory_(
+          new AstValueFactory(zone(), ast_string_constants(), hash_seed())) {}
+
+ReusableUnoptimizedCompileState::~ReusableUnoptimizedCompileState() = default;
 
 ParseInfo::ParseInfo(const UnoptimizedCompileFlags flags,
-                     UnoptimizedCompileState* state, uintptr_t stack_limit,
+                     UnoptimizedCompileState* state,
+                     ReusableUnoptimizedCompileState* reusable_state,
+                     uintptr_t stack_limit,
                      RuntimeCallStats* runtime_call_stats)
     : flags_(flags),
       state_(state),
-      zone_(std::make_unique<Zone>(state->allocator(), "parser-zone")),
+      reusable_state_(reusable_state),
       extension_(nullptr),
       script_scope_(nullptr),
       stack_limit_(stack_limit),
       parameters_end_pos_(kNoSourcePosition),
       max_function_literal_id_(kFunctionLiteralIdInvalid),
       character_stream_(nullptr),
-      ast_value_factory_(nullptr),
       function_name_(nullptr),
       runtime_call_stats_(runtime_call_stats),
       source_range_map_(nullptr),
@@ -212,13 +222,18 @@ ParseInfo::ParseInfo(const UnoptimizedCompileFlags flags,
 }
 
 ParseInfo::ParseInfo(Isolate* isolate, const UnoptimizedCompileFlags flags,
-                     UnoptimizedCompileState* state)
-    : ParseInfo(flags, state, isolate->stack_guard()->real_climit(),
+                     UnoptimizedCompileState* state,
+                     ReusableUnoptimizedCompileState* reusable_state)
+    : ParseInfo(flags, state, reusable_state,
+                isolate->stack_guard()->real_climit(),
                 isolate->counters()->runtime_call_stats()) {}
 
 ParseInfo::ParseInfo(LocalIsolate* isolate, const UnoptimizedCompileFlags flags,
-                     UnoptimizedCompileState* state, uintptr_t stack_limit)
-    : ParseInfo(flags, state, stack_limit, isolate->runtime_call_stats()) {}
+                     UnoptimizedCompileState* state,
+                     ReusableUnoptimizedCompileState* reusable_state,
+                     uintptr_t stack_limit)
+    : ParseInfo(flags, state, reusable_state, stack_limit,
+                isolate->runtime_call_stats()) {}
 
 ParseInfo::~ParseInfo() = default;
 
@@ -270,14 +285,6 @@ template EXPORT_TEMPLATE_DEFINE(V8_EXPORT_PRIVATE)
         MaybeHandle<FixedArray> maybe_wrapped_arguments,
         ScriptOriginOptions origin_options, NativesFlag natives);
 
-AstValueFactory* ParseInfo::GetOrCreateAstValueFactory() {
-  if (!ast_value_factory_.get()) {
-    ast_value_factory_.reset(
-        new AstValueFactory(zone(), ast_string_constants(), hash_seed()));
-  }
-  return ast_value_factory();
-}
-
 void ParseInfo::AllocateSourceRangeMap() {
   DCHECK(flags().block_coverage_enabled());
   DCHECK_NULL(source_range_map());

src/parsing/parse-info.h

@@ -161,39 +161,61 @@ class ParseInfo;
 // The mutable state for a parse + unoptimized compile operation.
 class V8_EXPORT_PRIVATE UnoptimizedCompileState {
  public:
-  explicit UnoptimizedCompileState(Isolate*);
-  UnoptimizedCompileState(const UnoptimizedCompileState& other) V8_NOEXCEPT;
+  const PendingCompilationErrorHandler* pending_error_handler() const {
+    return &pending_error_handler_;
+  }
+  PendingCompilationErrorHandler* pending_error_handler() {
+    return &pending_error_handler_;
+  }
+
+ private:
+  PendingCompilationErrorHandler pending_error_handler_;
+};
+
+// A container for ParseInfo fields that are reusable across multiple parses and
+// unoptimized compiles.
+//
+// Note that this is different from UnoptimizedCompileState, which has mutable
+// state for a single compilation that is not reusable across multiple
+// compilations.
+class V8_EXPORT_PRIVATE ReusableUnoptimizedCompileState {
+ public:
+  explicit ReusableUnoptimizedCompileState(Isolate* isolate);
+  explicit ReusableUnoptimizedCompileState(LocalIsolate* isolate);
+  ~ReusableUnoptimizedCompileState();
 
+  Zone* zone() { return &zone_; }
+  AstValueFactory* ast_value_factory() const {
+    return ast_value_factory_.get();
+  }
   uint64_t hash_seed() const { return hash_seed_; }
   AccountingAllocator* allocator() const { return allocator_; }
   const AstStringConstants* ast_string_constants() const {
     return ast_string_constants_;
   }
   Logger* logger() const { return logger_; }
-  PendingCompilationErrorHandler* pending_error_handler() {
-    return &pending_error_handler_;
-  }
-  const PendingCompilationErrorHandler* pending_error_handler() const {
-    return &pending_error_handler_;
-  }
   LazyCompileDispatcher* dispatcher() const { return dispatcher_; }
 
  private:
   uint64_t hash_seed_;
   AccountingAllocator* allocator_;
-  const AstStringConstants* ast_string_constants_;
-  PendingCompilationErrorHandler pending_error_handler_;
   Logger* logger_;
   LazyCompileDispatcher* dispatcher_;
+  const AstStringConstants* ast_string_constants_;
+  Zone zone_;
+  std::unique_ptr<AstValueFactory> ast_value_factory_;
 };
 
 // A container for the inputs, configuration options, and outputs of parsing.
 class V8_EXPORT_PRIVATE ParseInfo {
  public:
   ParseInfo(Isolate* isolate, const UnoptimizedCompileFlags flags,
-            UnoptimizedCompileState* state);
+            UnoptimizedCompileState* state,
+            ReusableUnoptimizedCompileState* reusable_state);
   ParseInfo(LocalIsolate* isolate, const UnoptimizedCompileFlags flags,
-            UnoptimizedCompileState* state, uintptr_t stack_limit);
+            UnoptimizedCompileState* state,
+            ReusableUnoptimizedCompileState* reusable_state,
+            uintptr_t stack_limit);
 
   ~ParseInfo();
 
@@ -204,26 +226,28 @@ class V8_EXPORT_PRIVATE ParseInfo {
                               ScriptOriginOptions origin_options,
                               NativesFlag natives = NOT_NATIVES_CODE);
 
-  // Either returns the ast-value-factory associcated with this ParseInfo, or
-  // creates and returns a new factory if none exists.
-  AstValueFactory* GetOrCreateAstValueFactory();
-
-  Zone* zone() const { return zone_.get(); }
+  Zone* zone() const { return reusable_state_->zone(); }
 
   const UnoptimizedCompileFlags& flags() const { return flags_; }
 
-  // Getters for state.
-  uint64_t hash_seed() const { return state_->hash_seed(); }
-  AccountingAllocator* allocator() const { return state_->allocator(); }
+  // Getters for reusable state.
+  uint64_t hash_seed() const { return reusable_state_->hash_seed(); }
+  AccountingAllocator* allocator() const {
+    return reusable_state_->allocator();
+  }
   const AstStringConstants* ast_string_constants() const {
-    return state_->ast_string_constants();
+    return reusable_state_->ast_string_constants();
+  }
+  Logger* logger() const { return reusable_state_->logger(); }
+  LazyCompileDispatcher* dispatcher() const {
+    return reusable_state_->dispatcher();
   }
-  Logger* logger() const { return state_->logger(); }
+  const UnoptimizedCompileState* state() const { return state_; }
+
+  // Getters for state.
   PendingCompilationErrorHandler* pending_error_handler() {
     return state_->pending_error_handler();
   }
-  LazyCompileDispatcher* dispatcher() const { return state_->dispatcher(); }
-  const UnoptimizedCompileState* state() const { return state_; }
 
   // Accessors for per-thread state.
   uintptr_t stack_limit() const { return stack_limit_; }
@@ -264,8 +288,7 @@ class V8_EXPORT_PRIVATE ParseInfo {
   }
 
   AstValueFactory* ast_value_factory() const {
-    DCHECK(ast_value_factory_.get());
-    return ast_value_factory_.get();
+    return reusable_state_->ast_value_factory();
   }
 
   const AstRawString* function_name() const { return function_name_; }
@@ -302,6 +325,7 @@ class V8_EXPORT_PRIVATE ParseInfo {
 
  private:
   ParseInfo(const UnoptimizedCompileFlags flags, UnoptimizedCompileState* state,
+            ReusableUnoptimizedCompileState* reusable_state,
             uintptr_t stack_limit, RuntimeCallStats* runtime_call_stats);
 
   void CheckFlagsForToplevelCompileFromScript(Script script,
@@ -310,8 +334,8 @@ class V8_EXPORT_PRIVATE ParseInfo {
   //------------- Inputs to parsing and scope analysis -----------------------
   const UnoptimizedCompileFlags flags_;
   UnoptimizedCompileState* state_;
+  ReusableUnoptimizedCompileState* reusable_state_;
 
-  std::unique_ptr<Zone> zone_;
   v8::Extension* extension_;
   DeclarationScope* script_scope_;
   uintptr_t stack_limit_;
@@ -321,7 +345,6 @@ class V8_EXPORT_PRIVATE ParseInfo {
   //----------- Inputs+Outputs of parsing and scope analysis -----------------
   std::unique_ptr<Utf16CharacterStream> character_stream_;
   std::unique_ptr<ConsumedPreparseData> consumed_preparse_data_;
-  std::unique_ptr<AstValueFactory> ast_value_factory_;
   const AstRawString* function_name_;
   RuntimeCallStats* runtime_call_stats_;
   SourceRangeMap* source_range_map_;  // Used when block coverage is enabled.

src/parsing/parser.cc

@@ -424,7 +424,7 @@ Parser::Parser(LocalIsolate* local_isolate, ParseInfo* info,
                Handle<Script> script)
     : ParserBase<Parser>(
           info->zone(), &scanner_, info->stack_limit(),
-          info->GetOrCreateAstValueFactory(), info->pending_error_handler(),
+          info->ast_value_factory(), info->pending_error_handler(),
           info->runtime_call_stats(), info->logger(), info->flags(), true),
       local_isolate_(local_isolate),
       info_(info),

test/cctest/parsing/test-preparser.cc

@@ -685,6 +685,7 @@ TEST(PreParserScopeAnalysis) {
       v8::base::SNPrintF(program, code, inner.params, inner.source);
 
       i::HandleScope scope(isolate);
+      i::ReusableUnoptimizedCompileState reusable_state(isolate);
 
       i::Handle<i::String> source =
           factory->InternalizeUtf8String(program.begin());
@@ -713,8 +714,9 @@ TEST(PreParserScopeAnalysis) {
       flags.set_is_lazy_compile(true);
 
       // Parse the lazy function using the scope data.
-      i::UnoptimizedCompileState using_scope_state(isolate);
-      i::ParseInfo using_scope_data(isolate, flags, &using_scope_state);
+      i::UnoptimizedCompileState using_scope_state;
+      i::ParseInfo using_scope_data(isolate, flags, &using_scope_state,
+                                    &reusable_state);
       using_scope_data.set_consumed_preparse_data(
           i::ConsumedPreparseData::For(isolate, produced_data_on_heap));
       CHECK(i::parsing::ParseFunction(&using_scope_data, shared, isolate,
@@ -727,8 +729,9 @@ TEST(PreParserScopeAnalysis) {
           scope_with_skipped_functions));
 
       // Parse the lazy function again eagerly to produce baseline data.
-      i::UnoptimizedCompileState not_using_scope_state(isolate);
-      i::ParseInfo not_using_scope_data(isolate, flags, &not_using_scope_state);
+      i::UnoptimizedCompileState not_using_scope_state;
+      i::ParseInfo not_using_scope_data(isolate, flags, &not_using_scope_state,
+                                        &reusable_state);
       CHECK(i::parsing::ParseFunction(&not_using_scope_data, shared, isolate,
                                       i::parsing::ReportStatisticsMode::kYes));
 
@@ -760,10 +763,11 @@ TEST(Regress753896) {
   i::Handle<i::String> source = factory->InternalizeUtf8String(
       "function lazy() { let v = 0; if (true) { var v = 0; } }");
   i::Handle<i::Script> script = factory->NewScript(source);
-  i::UnoptimizedCompileState state(isolate);
+  i::UnoptimizedCompileState state;
+  i::ReusableUnoptimizedCompileState reusable_state(isolate);
   i::UnoptimizedCompileFlags flags =
       i::UnoptimizedCompileFlags::ForScriptCompile(isolate, *script);
-  i::ParseInfo info(isolate, flags, &state);
+  i::ParseInfo info(isolate, flags, &state, &reusable_state);
 
   // We don't assert that parsing succeeded or that it failed; currently the
   // error is not detected inside lazy functions, but it might be in the future.

test/fuzzer/parser.cc

@@ -83,11 +83,12 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
 
   v8::internal::Handle<v8::internal::Script> script =
       factory->NewScript(source.ToHandleChecked());
-  v8::internal::UnoptimizedCompileState state(i_isolate);
+  v8::internal::UnoptimizedCompileState state;
+  v8::internal::ReusableUnoptimizedCompileState reusable_state(i_isolate);
   v8::internal::UnoptimizedCompileFlags flags =
       v8::internal::UnoptimizedCompileFlags::ForScriptCompile(i_isolate,
                                                               *script);
-  v8::internal::ParseInfo info(i_isolate, flags, &state);
+  v8::internal::ParseInfo info(i_isolate, flags, &state, &reusable_state);
   if (!v8::internal::parsing::ParseProgram(
           &info, script, i_isolate, i::parsing::ReportStatisticsMode::kYes)) {
     info.pending_error_handler()->PrepareErrors(i_isolate,

test/unittests/compiler-dispatcher/compiler-dispatcher-unittest.cc

@@ -19,6 +19,7 @@
 #include "src/objects/objects-inl.h"
 #include "src/parsing/parse-info.h"
 #include "src/parsing/parsing.h"
+#include "src/parsing/scanner-character-streams.h"
 #include "src/zone/zone-list-inl.h"
 #include "test/unittests/test-helpers.h"
 #include "test/unittests/test-utils.h"
@@ -74,13 +75,9 @@ class LazyCompileDispatcherTest : public TestWithNativeContext {
   static void EnqueueUnoptimizedCompileJob(LazyCompileDispatcher* dispatcher,
                                            Isolate* isolate,
                                            Handle<SharedFunctionInfo> shared) {
-    UnoptimizedCompileState state(isolate);
-    std::unique_ptr<ParseInfo> outer_parse_info =
-        test::OuterParseInfoForShared(isolate, shared, &state);
     if (dispatcher->IsEnqueued(shared)) return;
     dispatcher->Enqueue(isolate->main_thread_local_isolate(), shared,
-                        outer_parse_info->state(),
-                        outer_parse_info->character_stream()->Clone());
+                        test::SourceCharacterStreamForShared(isolate, shared));
   }
 };
 

test/unittests/heap/local-factory-unittest.cc

@@ -55,13 +55,13 @@ class LocalFactoryTest : public TestWithIsolateAndZone {
  public:
   LocalFactoryTest()
       : TestWithIsolateAndZone(),
-        state_(isolate()),
+        reusable_state_(isolate()),
         parse_info_(
             isolate(),
             UnoptimizedCompileFlags::ForToplevelCompile(
                 isolate(), true, construct_language_mode(FLAG_use_strict),
                 REPLMode::kNo, ScriptType::kClassic, FLAG_lazy),
-            &state_),
+            &state_, &reusable_state_),
         local_isolate_(isolate()->main_thread_local_isolate()) {}
 
   FunctionLiteral* ParseProgram(const char* source) {
@@ -105,6 +105,7 @@ class LocalFactoryTest : public TestWithIsolateAndZone {
  private:
   SaveFlags save_flags_;
   UnoptimizedCompileState state_;
+  ReusableUnoptimizedCompileState reusable_state_;
   ParseInfo parse_info_;
   LocalIsolate* local_isolate_;
   Handle<String> source_string_;

test/unittests/tasks/background-compile-task-unittest.cc

@@ -51,17 +51,8 @@ class BackgroundCompileTaskTest : public TestWithNativeContext {
   BackgroundCompileTask* NewBackgroundCompileTask(
       Isolate* isolate, Handle<SharedFunctionInfo> shared,
       size_t stack_size = FLAG_stack_size) {
-    UnoptimizedCompileState state(isolate);
-    std::unique_ptr<ParseInfo> outer_parse_info =
-        test::OuterParseInfoForShared(isolate, shared, &state);
-    AstValueFactory* ast_value_factory =
-        outer_parse_info->GetOrCreateAstValueFactory();
-    AstNodeFactory ast_node_factory(ast_value_factory,
-                                    outer_parse_info->zone());
-
     return new BackgroundCompileTask(
-        isolate, shared, outer_parse_info->state(),
-        outer_parse_info->character_stream()->Clone(),
+        isolate, shared, test::SourceCharacterStreamForShared(isolate, shared),
         isolate->counters()->worker_thread_runtime_call_stats(),
         isolate->counters()->compile_function_on_background(), FLAG_stack_size);
   }

test/unittests/test-helpers.cc

@@ -52,22 +52,15 @@ Handle<SharedFunctionInfo> CreateSharedFunctionInfo(
   return scope.CloseAndEscape(shared);
 }
 
-std::unique_ptr<ParseInfo> OuterParseInfoForShared(
-    Isolate* isolate, Handle<SharedFunctionInfo> shared,
-    UnoptimizedCompileState* state) {
-  Script script = Script::cast(shared->script());
-  std::unique_ptr<ParseInfo> result = std::make_unique<ParseInfo>(
-      isolate, i::UnoptimizedCompileFlags::ForScriptCompile(isolate, script),
-      state);
-
+std::unique_ptr<Utf16CharacterStream> SourceCharacterStreamForShared(
+    Isolate* isolate, Handle<SharedFunctionInfo> shared) {
   // Create a character stream to simulate the parser having done so for the
   // top-level ParseProgram.
+  Script script = Script::cast(shared->script());
   Handle<String> source(String::cast(script.source()), isolate);
   std::unique_ptr<Utf16CharacterStream> stream(
       ScannerStream::For(isolate, source));
-  result->set_character_stream(std::move(stream));
-
-  return result;
+  return stream;
 }
 
 }  // namespace test

test/unittests/test-helpers.h

@@ -8,7 +8,6 @@
 #include <memory>
 
 #include "include/v8-primitive.h"
-#include "src/parsing/parse-info.h"
 
 namespace v8 {
 
@@ -20,6 +19,9 @@ class Object;
 template <typename T>
 class Handle;
 class Isolate;
+class SharedFunctionInfo;
+class String;
+class Utf16CharacterStream;
 
 namespace test {
 
@@ -45,9 +47,8 @@ Handle<String> CreateSource(
 Handle<SharedFunctionInfo> CreateSharedFunctionInfo(
     Isolate* isolate,
     v8::String::ExternalOneByteStringResource* maybe_resource);
-std::unique_ptr<ParseInfo> OuterParseInfoForShared(
-    Isolate* isolate, Handle<SharedFunctionInfo> shared,
-    UnoptimizedCompileState* state);
+std::unique_ptr<Utf16CharacterStream> SourceCharacterStreamForShared(
+    Isolate* isolate, Handle<SharedFunctionInfo> shared);
 
 }  // namespace test
 }  // namespace internal