text: // Copyright 2012 the V8 project authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef V8_EXECUTION_ISOLATE_H_
  #define V8_EXECUTION_ISOLATE_H_
  
  #include <atomic>
  #include <cstddef>
  #include <functional>
  #include <memory>
  #include <queue>
  #include <unordered_map>
  #include <vector>
  
  #include "include/v8-inspector.h"
  #include "include/v8-internal.h"
  #include "include/v8-metrics.h"
  #include "include/v8.h"
  #include "src/base/macros.h"
  #include "src/base/platform/mutex.h"
  #include "src/builtins/builtins.h"
  #include "src/common/globals.h"
  #include "src/debug/interface-types.h"
  #include "src/execution/execution.h"
  #include "src/execution/external-pointer-table.h"
  #include "src/execution/futex-emulation.h"
  #include "src/execution/isolate-data.h"
  #include "src/execution/messages.h"
  #include "src/execution/stack-guard.h"
  #include "src/handles/handles.h"
  #include "src/heap/factory.h"
  #include "src/heap/heap.h"
  #include "src/heap/read-only-heap.h"
  #include "src/init/isolate-allocator.h"
  #include "src/objects/code.h"
  #include "src/objects/contexts.h"
  #include "src/objects/debug-objects.h"
  #include "src/runtime/runtime.h"
  #include "src/strings/unicode.h"
  #include "src/utils/allocation.h"
  
  #ifdef V8_INTL_SUPPORT
  #include "unicode/uversion.h"  // Define U_ICU_NAMESPACE.
  namespace U_ICU_NAMESPACE {
  class UMemory;
  }  // namespace U_ICU_NAMESPACE
  #endif  // V8_INTL_SUPPORT
  
  namespace v8 {
  
  namespace base {
  class RandomNumberGenerator;
  }  // namespace base
  
  namespace debug {
  class ConsoleDelegate;
  class AsyncEventDelegate;
  }  // namespace debug
  
  namespace internal {
  
  namespace heap {
  class HeapTester;
  }  // namespace heap
  
  class AddressToIndexHashMap;
  class AstStringConstants;
  class Bootstrapper;
  class BuiltinsConstantsTableBuilder;
  class CancelableTaskManager;
  class CodeEventDispatcher;
  class CodeTracer;
  class CommonFrame;
  class CompilationCache;
  class CompilationStatistics;
  class CompilerDispatcher;
  class Counters;
  class Debug;
  class Deoptimizer;
  class DescriptorLookupCache;
  class EmbeddedFileWriterInterface;
  class EternalHandles;
  class HandleScopeImplementer;
  class HeapObjectToIndexHashMap;
  class HeapProfiler;
  class InnerPointerToCodeCache;
  class Logger;
  class MaterializedObjectStore;
  class Microtask;
  class MicrotaskQueue;
  class OptimizingCompileDispatcher;
  class PersistentHandles;
  class PersistentHandlesList;
  class ReadOnlyArtifacts;
  class RegExpStack;
  class RootVisitor;
  class RuntimeProfiler;
  class SetupIsolateDelegate;
  class Simulator;
  class SnapshotData;
  class StringTable;
  class StubCache;
  class ThreadManager;
  class ThreadState;
  class ThreadVisitor;  // Defined in v8threads.h
  class TracingCpuProfilerImpl;
  class UnicodeCache;
  struct ManagedPtrDestructor;
  
  template <StateTag Tag>
  class VMState;
  
  namespace interpreter {
  class Interpreter;
  }  // namespace interpreter
  
  namespace compiler {
  class PerIsolateCompilerCache;
  }  // namespace compiler
  
  namespace wasm {
  class WasmEngine;
  }  // namespace wasm
  
  namespace win64_unwindinfo {
  class BuiltinUnwindInfo;
  }  // namespace win64_unwindinfo
  
  namespace metrics {
  class Recorder;
  }  // namespace metrics
  
  #define RETURN_FAILURE_IF_SCHEDULED_EXCEPTION(isolate) \
    do {                                                 \
      Isolate* __isolate__ = (isolate);                  \
      DCHECK(!__isolate__->has_pending_exception());     \
      if (__isolate__->has_scheduled_exception()) {      \
        return __isolate__->PromoteScheduledException(); \
      }                                                  \
    } while (false)
  
  // Macros for MaybeHandle.
  
  #define RETURN_VALUE_IF_SCHEDULED_EXCEPTION(isolate, value) \
    do {                                                      \
      Isolate* __isolate__ = (isolate);                       \
      DCHECK(!__isolate__->has_pending_exception());          \
      if (__isolate__->has_scheduled_exception()) {           \
        __isolate__->PromoteScheduledException();             \
        return value;                                         \
      }                                                       \
    } while (false)
  
  #define RETURN_EXCEPTION_IF_SCHEDULED_EXCEPTION(isolate, T) \
    RETURN_VALUE_IF_SCHEDULED_EXCEPTION(isolate, MaybeHandle<T>())
  
  #define ASSIGN_RETURN_ON_SCHEDULED_EXCEPTION_VALUE(isolate, dst, call, value) \
    do {                                                                        \
      Isolate* __isolate__ = (isolate);                                         \
      if (!(call).ToLocal(&dst)) {                                              \
        DCHECK(__isolate__->has_scheduled_exception());                         \
        __isolate__->PromoteScheduledException();                               \
        return value;                                                           \
      }                                                                         \
    } while (false)
  
  #define RETURN_ON_SCHEDULED_EXCEPTION_VALUE(isolate, call, value) \
    do {                                                            \
      Isolate* __isolate__ = (isolate);                             \
      if ((call).IsNothing()) {                                     \
        DCHECK(__isolate__->has_scheduled_exception());             \
        __isolate__->PromoteScheduledException();                   \
        return value;                                               \
      }                                                             \
    } while (false)
  
  /**
   * RETURN_RESULT_OR_FAILURE is used in functions with return type Object (such
   * as "RUNTIME_FUNCTION(...) {...}" or "BUILTIN(...) {...}" ) to return either
   * the contents of a MaybeHandle<X>, or the "exception" sentinel value.
   * Example usage:
   *
   * RUNTIME_FUNCTION(Runtime_Func) {
   *   ...
   *   RETURN_RESULT_OR_FAILURE(
   *       isolate,
   *       FunctionWithReturnTypeMaybeHandleX(...));
   * }
   *
   * If inside a function with return type MaybeHandle<X> use RETURN_ON_EXCEPTION
   * instead.
   * If inside a function with return type Handle<X>, or Maybe<X> use
   * RETURN_ON_EXCEPTION_VALUE instead.
   */
  #define RETURN_RESULT_OR_FAILURE(isolate, call)      \
    do {                                               \
      Handle<Object> __result__;                       \
      Isolate* __isolate__ = (isolate);                \
      if (!(call).ToHandle(&__result__)) {             \
        DCHECK(__isolate__->has_pending_exception());  \
        return ReadOnlyRoots(__isolate__).exception(); \
      }                                                \
      DCHECK(!__isolate__->has_pending_exception());   \
      return *__result__;                              \
    } while (false)
  
  #define ASSIGN_RETURN_ON_EXCEPTION_VALUE(isolate, dst, call, value) \
    do {                                                              \
      if (!(call).ToHandle(&dst)) {                                   \
        DCHECK((isolate)->has_pending_exception());                   \
        return value;                                                 \
      }                                                               \
    } while (false)
  
  #define ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, dst, call)                \
    do {                                                                        \
      auto* __isolate__ = (isolate);                                            \
      ASSIGN_RETURN_ON_EXCEPTION_VALUE(__isolate__, dst, call,                  \
                                       ReadOnlyRoots(__isolate__).exception()); \
    } while (false)
  
  #define ASSIGN_RETURN_ON_EXCEPTION(isolate, dst, call, T) \
    ASSIGN_RETURN_ON_EXCEPTION_VALUE(isolate, dst, call, MaybeHandle<T>())
  
  #define THROW_NEW_ERROR(isolate, call, T)                                \
    do {                                                                   \
      auto* __isolate__ = (isolate);                                       \
      return __isolate__->template Throw<T>(__isolate__->factory()->call); \
    } while (false)
  
  #define THROW_NEW_ERROR_RETURN_FAILURE(isolate, call)         \
    do {                                                        \
      auto* __isolate__ = (isolate);                            \
      return __isolate__->Throw(*__isolate__->factory()->call); \
    } while (false)
  
  #define THROW_NEW_ERROR_RETURN_VALUE(isolate, call, value) \
    do {                                                     \
      auto* __isolate__ = (isolate);                         \
      __isolate__->Throw(*__isolate__->factory()->call);     \
      return value;                                          \
    } while (false)
  
  /**
   * RETURN_ON_EXCEPTION_VALUE conditionally returns the given value when the
   * given MaybeHandle is empty. It is typically used in functions with return
   * type Maybe<X> or Handle<X>. Example usage:
   *
   * Handle<X> Func() {
   *   ...
   *   RETURN_ON_EXCEPTION_VALUE(
   *       isolate,
   *       FunctionWithReturnTypeMaybeHandleX(...),
   *       Handle<X>());
   *   // code to handle non exception
   *   ...
   * }
   *
   * Maybe<bool> Func() {
   *   ..
   *   RETURN_ON_EXCEPTION_VALUE(
   *       isolate,
   *       FunctionWithReturnTypeMaybeHandleX(...),
   *       Nothing<bool>);
   *   // code to handle non exception
   *   return Just(true);
   * }
   *
   * If inside a function with return type MaybeHandle<X>, use RETURN_ON_EXCEPTION
   * instead.
   * If inside a function with return type Object, use
   * RETURN_FAILURE_ON_EXCEPTION instead.
   */
  #define RETURN_ON_EXCEPTION_VALUE(isolate, call, value) \
    do {                                                  \
      if ((call).is_null()) {                             \
        DCHECK((isolate)->has_pending_exception());       \
        return value;                                     \
      }                                                   \
    } while (false)
  
  /**
   * RETURN_FAILURE_ON_EXCEPTION conditionally returns the "exception" sentinel if
   * the given MaybeHandle is empty; so it can only be used in functions with
   * return type Object, such as RUNTIME_FUNCTION(...) {...} or BUILTIN(...)
   * {...}. Example usage:
   *
   * RUNTIME_FUNCTION(Runtime_Func) {
   *   ...
   *   RETURN_FAILURE_ON_EXCEPTION(
   *       isolate,
   *       FunctionWithReturnTypeMaybeHandleX(...));
   *   // code to handle non exception
   *   ...
   * }
   *
   * If inside a function with return type MaybeHandle<X>, use RETURN_ON_EXCEPTION
   * instead.
   * If inside a function with return type Maybe<X> or Handle<X>, use
   * RETURN_ON_EXCEPTION_VALUE instead.
   */
  #define RETURN_FAILURE_ON_EXCEPTION(isolate, call)                     \
    do {                                                                 \
      Isolate* __isolate__ = (isolate);                                  \
      RETURN_ON_EXCEPTION_VALUE(__isolate__, call,                       \
                                ReadOnlyRoots(__isolate__).exception()); \
    } while (false);
  
  /**
   * RETURN_ON_EXCEPTION conditionally returns an empty MaybeHandle<T> if the
   * given MaybeHandle is empty. Use it to return immediately from a function with
   * return type MaybeHandle when an exception was thrown. Example usage:
   *
   * MaybeHandle<X> Func() {
   *   ...
   *   RETURN_ON_EXCEPTION(
   *       isolate,
   *       FunctionWithReturnTypeMaybeHandleY(...),
   *       X);
   *   // code to handle non exception
   *   ...
   * }
   *
   * If inside a function with return type Object, use
   * RETURN_FAILURE_ON_EXCEPTION instead.
   * If inside a function with return type
   * Maybe<X> or Handle<X>, use RETURN_ON_EXCEPTION_VALUE instead.
   */
  #define RETURN_ON_EXCEPTION(isolate, call, T) \
    RETURN_ON_EXCEPTION_VALUE(isolate, call, MaybeHandle<T>())
  
  #define RETURN_FAILURE(isolate, should_throw, call) \
    do {                                              \
      if ((should_throw) == kDontThrow) {             \
        return Just(false);                           \
      } else {                                        \
        isolate->Throw(*isolate->factory()->call);    \
        return Nothing<bool>();                       \
      }                                               \
    } while (false)
  
  #define MAYBE_RETURN(call, value)         \
    do {                                    \
      if ((call).IsNothing()) return value; \
    } while (false)
  
  #define MAYBE_RETURN_NULL(call) MAYBE_RETURN(call, MaybeHandle<Object>())
  
  #define MAYBE_ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, dst, call) \
    do {                                                               \
      Isolate* __isolate__ = (isolate);                                \
      if (!(call).To(&dst)) {                                          \
        DCHECK(__isolate__->has_pending_exception());                  \
        return ReadOnlyRoots(__isolate__).exception();                 \
      }                                                                \
    } while (false)
  
  #define FOR_WITH_HANDLE_SCOPE(isolate, loop_var_type, init, loop_var,      \
                                limit_check, increment, body)                \
    do {                                                                     \
      loop_var_type init;                                                    \
      loop_var_type for_with_handle_limit = loop_var;                        \
      Isolate* for_with_handle_isolate = isolate;                            \
      while (limit_check) {                                                  \
        for_with_handle_limit += 1024;                                       \
        HandleScope loop_scope(for_with_handle_isolate);                     \
        for (; limit_check && loop_var < for_with_handle_limit; increment) { \
          body                                                               \
        }                                                                    \
      }                                                                      \
    } while (false)
  
  #define WHILE_WITH_HANDLE_SCOPE(isolate, limit_check, body)                  \
    do {                                                                       \
      Isolate* for_with_handle_isolate = isolate;                              \
      while (limit_check) {                                                    \
        HandleScope loop_scope(for_with_handle_isolate);                       \
        for (int for_with_handle_it = 0;                                       \
             limit_check && for_with_handle_it < 1024; ++for_with_handle_it) { \
          body                                                                 \
        }                                                                      \
      }                                                                        \
    } while (false)
  
  #define FIELD_ACCESSOR(type, name)                \
    inline void set_##name(type v) { name##_ = v; } \
    inline type name() const { return name##_; }
  
  // Controls for manual embedded blob lifecycle management, used by tests and
  // mksnapshot.
  V8_EXPORT_PRIVATE void DisableEmbeddedBlobRefcounting();
  V8_EXPORT_PRIVATE void FreeCurrentEmbeddedBlob();
  
  #ifdef DEBUG
  
  #define ISOLATE_INIT_DEBUG_ARRAY_LIST(V)               \
    V(CommentStatistic, paged_space_comments_statistics, \
      CommentStatistic::kMaxComments + 1)                \
    V(int, code_kind_statistics, kCodeKindCount)
  #else
  
  #define ISOLATE_INIT_DEBUG_ARRAY_LIST(V)
  
  #endif
  
  #define ISOLATE_INIT_ARRAY_LIST(V)                                             \
    /* SerializerDeserializer state. */                                          \
    V(int32_t, jsregexp_static_offsets_vector, kJSRegexpStaticOffsetsVectorSize) \
    V(int, bad_char_shift_table, kUC16AlphabetSize)                              \
    V(int, good_suffix_shift_table, (kBMMaxShift + 1))                           \
    V(int, suffix_table, (kBMMaxShift + 1))                                      \
    ISOLATE_INIT_DEBUG_ARRAY_LIST(V)
  
  using DebugObjectCache = std::vector<Handle<HeapObject>>;
  
  #define ISOLATE_INIT_LIST(V)                                                   \
    /* Assembler state. */                                                       \
    V(FatalErrorCallback, exception_behavior, nullptr)                           \
    V(OOMErrorCallback, oom_behavior, nullptr)                                   \
    V(LogEventCallback, event_logger, nullptr)                                   \
    V(AllowCodeGenerationFromStringsCallback, allow_code_gen_callback, nullptr)  \
    V(ModifyCodeGenerationFromStringsCallback, modify_code_gen_callback,         \
      nullptr)                                                                   \
    V(AllowWasmCodeGenerationCallback, allow_wasm_code_gen_callback, nullptr)    \
    V(ExtensionCallback, wasm_module_callback, &NoExtension)                     \
    V(ExtensionCallback, wasm_instance_callback, &NoExtension)                   \
    V(WasmStreamingCallback, wasm_streaming_callback, nullptr)                   \
    V(WasmThreadsEnabledCallback, wasm_threads_enabled_callback, nullptr)        \
    V(WasmLoadSourceMapCallback, wasm_load_source_map_callback, nullptr)         \
    V(WasmSimdEnabledCallback, wasm_simd_enabled_callback, nullptr)              \
    /* State for Relocatable. */                                                 \
    V(Relocatable*, relocatable_top, nullptr)                                    \
    V(DebugObjectCache*, string_stream_debug_object_cache, nullptr)              \
    V(Object, string_stream_current_security_token, Object())                    \
    V(const intptr_t*, api_external_references, nullptr)                         \
    V(AddressToIndexHashMap*, external_reference_map, nullptr)                   \
    V(HeapObjectToIndexHashMap*, root_index_map, nullptr)                        \
    V(MicrotaskQueue*, default_microtask_queue, nullptr)                         \
    V(CompilationStatistics*, turbo_statistics, nullptr)                         \
    V(CodeTracer*, code_tracer, nullptr)                                         \
    V(uint32_t, per_isolate_assert_data, 0xFFFFFFFFu)                            \
    V(PromiseRejectCallback, promise_reject_callback, nullptr)                   \
    V(const v8::StartupData*, snapshot_blob, nullptr)                            \
    V(int, code_and_metadata_size, 0)                                            \
    V(int, bytecode_and_metadata_size, 0)                                        \
    V(int, external_script_source_size, 0)                                       \
    /* Number of CPU profilers running on the isolate. */                        \
    V(size_t, num_cpu_profilers, 0)                                              \
    /* true if a trace is being formatted through Error.prepareStackTrace. */    \
    V(bool, formatting_stack_trace, false)                                       \
    /* Perform side effect checks on function call and API callbacks. */         \
    V(DebugInfo::ExecutionMode, debug_execution_mode, DebugInfo::kBreakpoints)   \
    /* Current code coverage mode */                                             \
    V(debug::CoverageMode, code_coverage_mode, debug::CoverageMode::kBestEffort) \
    V(debug::TypeProfileMode, type_profile_mode, debug::TypeProfileMode::kNone)  \
    V(int, last_console_context_id, 0)                                           \
    V(v8_inspector::V8Inspector*, inspector, nullptr)                            \
    V(bool, next_v8_call_is_safe_for_termination, false)                         \
    V(bool, only_terminate_in_safe_scope, false)                                 \
    V(bool, detailed_source_positions_for_profiling, FLAG_detailed_line_info)    \
    V(int, embedder_wrapper_type_index, -1)                                      \
    V(int, embedder_wrapper_object_index, -1)
  
  #define THREAD_LOCAL_TOP_ACCESSOR(type, name)                         \
    inline void set_##name(type v) { thread_local_top()->name##_ = v; } \
    inline type name() const { return thread_local_top()->name##_; }
  
  #define THREAD_LOCAL_TOP_ADDRESS(type, name) \
    type* name##_address() { return &thread_local_top()->name##_; }
  
  // HiddenFactory exists so Isolate can privately inherit from it without making
  // Factory's members available to Isolate directly.
  class V8_EXPORT_PRIVATE HiddenFactory : private Factory {};
  
  class V8_EXPORT_PRIVATE Isolate final : private HiddenFactory {
    // These forward declarations are required to make the friend declarations in
    // PerIsolateThreadData work on some older versions of gcc.
    class ThreadDataTable;
    class EntryStackItem;
  
   public:
    using HandleScopeType = HandleScope;
    void* operator new(size_t) = delete;
    void operator delete(void*) = delete;
  
    // A thread has a PerIsolateThreadData instance for each isolate that it has
    // entered. That instance is allocated when the isolate is initially entered
    // and reused on subsequent entries.
    class PerIsolateThreadData {
     public:
      PerIsolateThreadData(Isolate* isolate, ThreadId thread_id)
          : isolate_(isolate),
            thread_id_(thread_id),
            stack_limit_(0),
            thread_state_(nullptr)
  #if USE_SIMULATOR
            ,
            simulator_(nullptr)
  #endif
      {
      }
      ~PerIsolateThreadData();
      Isolate* isolate() const { return isolate_; }
      ThreadId thread_id() const { return thread_id_; }
  
      FIELD_ACCESSOR(uintptr_t, stack_limit)
      FIELD_ACCESSOR(ThreadState*, thread_state)
  
  #if USE_SIMULATOR
      FIELD_ACCESSOR(Simulator*, simulator)
  #endif
  
      bool Matches(Isolate* isolate, ThreadId thread_id) const {
        return isolate_ == isolate && thread_id_ == thread_id;
      }
  
     private:
      Isolate* isolate_;
      ThreadId thread_id_;
      uintptr_t stack_limit_;
      ThreadState* thread_state_;
  
  #if USE_SIMULATOR
      Simulator* simulator_;
  #endif
  
      friend class Isolate;
      friend class ThreadDataTable;
      friend class EntryStackItem;
  
      DISALLOW_COPY_AND_ASSIGN(PerIsolateThreadData);
    };
  
    static void InitializeOncePerProcess();
  
    // Creates Isolate object. Must be used instead of constructing Isolate with
    // new operator.
    static Isolate* New();
  
    // Deletes Isolate object. Must be used instead of delete operator.
    // Destroys the non-default isolates.
    // Sets default isolate into "has_been_disposed" state rather then destroying,
    // for legacy API reasons.
    static void Delete(Isolate* isolate);
  
    void SetUpFromReadOnlyArtifacts(std::shared_ptr<ReadOnlyArtifacts> artifacts,
                                    ReadOnlyHeap* ro_heap);
    void set_read_only_heap(ReadOnlyHeap* ro_heap) { read_only_heap_ = ro_heap; }
  
    // Page allocator that must be used for allocating V8 heap pages.
    v8::PageAllocator* page_allocator();
  
    // Returns the PerIsolateThreadData for the current thread (or nullptr if one
    // is not currently set).
    static PerIsolateThreadData* CurrentPerIsolateThreadData() {
      return reinterpret_cast<PerIsolateThreadData*>(
          base::Thread::GetThreadLocal(per_isolate_thread_data_key_));
    }
  
    // Returns the isolate inside which the current thread is running or nullptr.
    V8_INLINE static Isolate* TryGetCurrent() {
      DCHECK_EQ(true, isolate_key_created_.load(std::memory_order_relaxed));
      return reinterpret_cast<Isolate*>(
          base::Thread::GetExistingThreadLocal(isolate_key_));
    }
  
    // Returns the isolate inside which the current thread is running.
    V8_INLINE static Isolate* Current() {
      Isolate* isolate = TryGetCurrent();
      DCHECK_NOT_NULL(isolate);
      return isolate;
    }
  
    // Usually called by Init(), but can be called early e.g. to allow
    // testing components that require logging but not the whole
    // isolate.
    //
    // Safe to call more than once.
    void InitializeLoggingAndCounters();
    bool InitializeCounters();  // Returns false if already initialized.
  
    bool InitWithoutSnapshot();
    bool InitWithSnapshot(SnapshotData* startup_snapshot_data,
                          SnapshotData* read_only_snapshot_data, bool can_rehash);
  
    // True if at least one thread Enter'ed this isolate.
    bool IsInUse() { return entry_stack_ != nullptr; }
  
    void ReleaseSharedPtrs();
  
    void ClearSerializerData();
  
    bool LogObjectRelocation();
  
    // Initializes the current thread to run this Isolate.
    // Not thread-safe. Multiple threads should not Enter/Exit the same isolate
    // at the same time, this should be prevented using external locking.
    void Enter();
  
    // Exits the current thread. The previosuly entered Isolate is restored
    // for the thread.
    // Not thread-safe. Multiple threads should not Enter/Exit the same isolate
    // at the same time, this should be prevented using external locking.
    void Exit();
  
    // Find the PerThread for this particular (isolate, thread) combination.
    // If one does not yet exist, allocate a new one.
    PerIsolateThreadData* FindOrAllocatePerThreadDataForThisThread();
  
    // Find the PerThread for this particular (isolate, thread) combination
    // If one does not yet exist, return null.
    PerIsolateThreadData* FindPerThreadDataForThisThread();
  
    // Find the PerThread for given (isolate, thread) combination
    // If one does not yet exist, return null.
    PerIsolateThreadData* FindPerThreadDataForThread(ThreadId thread_id);
  
    // Discard the PerThread for this particular (isolate, thread) combination
    // If one does not yet exist, no-op.
    void DiscardPerThreadDataForThisThread();
  
    // Mutex for serializing access to break control structures.
    base::RecursiveMutex* break_access() { return &break_access_; }
  
    // Shared mutex for allowing concurrent read/writes to TransitionArrays.
    base::SharedMutex* transition_array_access() {
      return &transition_array_access_;
    }
  
    // The isolate's string table.
    StringTable* string_table() { return string_table_.get(); }
  
    Address get_address_from_id(IsolateAddressId id);
  
    // Access to top context (where the current function object was created).
    Context context() { return thread_local_top()->context_; }
    inline void set_context(Context context);
    Context* context_address() { return &thread_local_top()->context_; }
  
    // Access to current thread id.
    THREAD_LOCAL_TOP_ACCESSOR(ThreadId, thread_id)
  
    // Interface to pending exception.
    inline Object pending_exception();
    inline void set_pending_exception(Object exception_obj);
    inline void clear_pending_exception();
  
    bool AreWasmThreadsEnabled(Handle<Context> context);
    bool IsWasmSimdEnabled(Handle<Context> context);
  
    THREAD_LOCAL_TOP_ADDRESS(Object, pending_exception)
  
    inline bool has_pending_exception();
  
    THREAD_LOCAL_TOP_ADDRESS(Context, pending_handler_context)
    THREAD_LOCAL_TOP_ADDRESS(Address, pending_handler_entrypoint)
    THREAD_LOCAL_TOP_ADDRESS(Address, pending_handler_constant_pool)
    THREAD_LOCAL_TOP_ADDRESS(Address, pending_handler_fp)
    THREAD_LOCAL_TOP_ADDRESS(Address, pending_handler_sp)
  
    THREAD_LOCAL_TOP_ACCESSOR(bool, external_caught_exception)
  
    v8::TryCatch* try_catch_handler() {
      return thread_local_top()->try_catch_handler_;
    }
    bool* external_caught_exception_address() {
      return &thread_local_top()->external_caught_exception_;
    }
  
    THREAD_LOCAL_TOP_ADDRESS(Object, scheduled_exception)
  
    inline void clear_pending_message();
    Address pending_message_obj_address() {
      return reinterpret_cast<Address>(&thread_local_top()->pending_message_obj_);
    }
  
    inline Object scheduled_exception();
    inline bool has_scheduled_exception();
    inline void clear_scheduled_exception();
  
    bool IsJavaScriptHandlerOnTop(Object exception);
    bool IsExternalHandlerOnTop(Object exception);
  
    inline bool is_catchable_by_javascript(Object exception);
    inline bool is_catchable_by_wasm(Object exception);
  
    // JS execution stack (see frames.h).
    static Address c_entry_fp(ThreadLocalTop* thread) {
      return thread->c_entry_fp_;
    }
    static Address handler(ThreadLocalTop* thread) { return thread->handler_; }
    Address c_function() { return thread_local_top()->c_function_; }
  
    inline Address* c_entry_fp_address() {
      return &thread_local_top()->c_entry_fp_;
    }
    static uint32_t c_entry_fp_offset() {
      return static_cast<uint32_t>(
          OFFSET_OF(Isolate, thread_local_top()->c_entry_fp_) -
          isolate_root_bias());
    }
    inline Address* handler_address() { return &thread_local_top()->handler_; }
    inline Address* c_function_address() {
      return &thread_local_top()->c_function_;
    }
  
  #if defined(DEBUG) || defined(VERIFY_HEAP)
    // Count the number of active deserializers, so that the heap verifier knows
    // whether there is currently an active deserialization happening.
    //
    // This is needed as the verifier currently doesn't support verifying objects
    // which are partially deserialized.
    //
    // TODO(leszeks): Make the verifier a bit more deserialization compatible.
    void RegisterDeserializerStarted() { ++num_active_deserializers_; }
    void RegisterDeserializerFinished() {
      CHECK_GE(--num_active_deserializers_, 0);
    }
    bool has_active_deserializer() const {
      return num_active_deserializers_.load(std::memory_order_acquire) > 0;
    }
  #else
    void RegisterDeserializerStarted() {}
    void RegisterDeserializerFinished() {}
    bool has_active_deserializer() const { UNREACHABLE(); }
  #endif
  
    // Bottom JS entry.
    Address js_entry_sp() { return thread_local_top()->js_entry_sp_; }
    inline Address* js_entry_sp_address() {
      return &thread_local_top()->js_entry_sp_;
    }
  
    std::vector<MemoryRange>* GetCodePages() const;
  
    void SetCodePages(std::vector<MemoryRange>* new_code_pages);
  
    // Returns the global object of the current context. It could be
    // a builtin object, or a JS global object.
    inline Handle<JSGlobalObject> global_object();
  
    // Returns the global proxy object of the current context.
    inline Handle<JSGlobalProxy> global_proxy();
  
    static int ArchiveSpacePerThread() { return sizeof(ThreadLocalTop); }
    void FreeThreadResources() { thread_local_top()->Free(); }
  
    // This method is called by the api after operations that may throw
    // exceptions.  If an exception was thrown and not handled by an external
    // handler the exception is scheduled to be rethrown when we return to running
    // JavaScript code.  If an exception is scheduled true is returned.
    bool OptionalRescheduleException(bool clear_exception);
  
    // Push and pop a promise and the current try-catch handler.
    void PushPromise(Handle<JSObject> promise);
    void PopPromise();
  
    // Return the relevant Promise that a throw/rejection pertains to, based
    // on the contents of the Promise stack
    Handle<Object> GetPromiseOnStackOnThrow();
  
    // Heuristically guess whether a Promise is handled by user catch handler
    bool PromiseHasUserDefinedRejectHandler(Handle<JSPromise> promise);
  
    class ExceptionScope {
     public:
      // Scope currently can only be used for regular exceptions,
      // not termination exception.
      inline explicit ExceptionScope(Isolate* isolate);
      inline ~ExceptionScope();
  
     private:
      Isolate* isolate_;
      Handle<Object> pending_exception_;
    };
  
    void SetCaptureStackTraceForUncaughtExceptions(
        bool capture, int frame_limit, StackTrace::StackTraceOptions options);
    bool get_capture_stack_trace_for_uncaught_exceptions() const;
  
    void SetAbortOnUncaughtExceptionCallback(
        v8::Isolate::AbortOnUncaughtExceptionCallback callback);
  
    enum PrintStackMode { kPrintStackConcise, kPrintStackVerbose };
    void PrintCurrentStackTrace(FILE* out);
    void PrintStack(StringStream* accumulator,
                    PrintStackMode mode = kPrintStackVerbose);
    void PrintStack(FILE* out, PrintStackMode mode = kPrintStackVerbose);
    Handle<String> StackTraceString();
    // Stores a stack trace in a stack-allocated temporary buffer which will
    // end up in the minidump for debugging purposes.
    V8_NOINLINE void PushStackTraceAndDie(void* ptr1 = nullptr,
                                          void* ptr2 = nullptr,
                                          void* ptr3 = nullptr,
                                          void* ptr4 = nullptr);
    Handle<FixedArray> CaptureCurrentStackTrace(
        int frame_limit, StackTrace::StackTraceOptions options);
    Handle<Object> CaptureSimpleStackTrace(Handle<JSReceiver> error_object,
                                           FrameSkipMode mode,
                                           Handle<Object> caller);
    MaybeHandle<JSReceiver> CaptureAndSetDetailedStackTrace(
        Handle<JSReceiver> error_object);
    MaybeHandle<JSReceiver> CaptureAndSetSimpleStackTrace(
        Handle<JSReceiver> error_object, FrameSkipMode mode,
        Handle<Object> caller);
    Handle<FixedArray> GetDetailedStackTrace(Handle<JSObject> error_object);
  
    Address GetAbstractPC(int* line, int* column);
  
    // Returns if the given context may access the given global object. If
    // the result is false, the pending exception is guaranteed to be
    // set.
    bool MayAccess(Handle<Context> accessing_context, Handle<JSObject> receiver);
  
    void SetFailedAccessCheckCallback(v8::FailedAccessCheckCallback callback);
    void ReportFailedAccessCheck(Handle<JSObject> receiver);
  
    // Exception throwing support. The caller should use the result
    // of Throw() as its return value.
    Object Throw(Object exception, MessageLocation* location = nullptr);
    Object ThrowIllegalOperation();
  
    template <typename T>
    V8_WARN_UNUSED_RESULT MaybeHandle<T> Throw(
        Handle<Object> exception, MessageLocation* location = nullptr) {
      Throw(*exception, location);
      return MaybeHandle<T>();
    }
  
    void ThrowAt(Handle<JSObject> exception, MessageLocation* location);
  
    void FatalProcessOutOfHeapMemory(const char* location) {
      heap()->FatalProcessOutOfMemory(location);
    }
  
    void set_console_delegate(debug::ConsoleDelegate* delegate) {
      console_delegate_ = delegate;
    }
    debug::ConsoleDelegate* console_delegate() { return console_delegate_; }
  
    void set_async_event_delegate(debug::AsyncEventDelegate* delegate) {
      async_event_delegate_ = delegate;
      PromiseHookStateUpdated();
    }
    void OnAsyncFunctionStateChanged(Handle<JSPromise> promise,
                                     debug::DebugAsyncActionType);
  
    // Re-throw an exception.  This involves no error reporting since error
    // reporting was handled when the exception was thrown originally.
    Object ReThrow(Object exception);
  
    // Find the correct handler for the current pending exception. This also
    // clears and returns the current pending exception.
    Object UnwindAndFindHandler();
  
    // Tries to predict whether an exception will be caught. Note that this can
    // only produce an estimate, because it is undecidable whether a finally
    // clause will consume or re-throw an exception.
    enum CatchType {
      NOT_CAUGHT,
      CAUGHT_BY_JAVASCRIPT,
      CAUGHT_BY_EXTERNAL,
      CAUGHT_BY_DESUGARING,
      CAUGHT_BY_PROMISE,
      CAUGHT_BY_ASYNC_AWAIT
    };
    CatchType PredictExceptionCatcher();
  
    void ScheduleThrow(Object exception);
    // Re-set pending message, script and positions reported to the TryCatch
    // back to the TLS for re-use when rethrowing.
    void RestorePendingMessageFromTryCatch(v8::TryCatch* handler);
    // Un-schedule an exception that was caught by a TryCatch handler.
    void CancelScheduledExceptionFromTryCatch(v8::TryCatch* handler);
    void ReportPendingMessages();
  
    // Promote a scheduled exception to pending. Asserts has_scheduled_exception.
    Object PromoteScheduledException();
  
    // Attempts to compute the current source location, storing the
    // result in the target out parameter. The source location is attached to a
    // Message object as the location which should be shown to the user. It's
    // typically the top-most meaningful location on the stack.
    bool ComputeLocation(MessageLocation* target);
    bool ComputeLocationFromException(MessageLocation* target,
                                      Handle<Object> exception);
    bool ComputeLocationFromStackTrace(MessageLocation* target,
                                       Handle<Object> exception);
  
    Handle<JSMessageObject> CreateMessage(Handle<Object> exception,
                                          MessageLocation* location);
    Handle<JSMessageObject> CreateMessageOrAbort(Handle<Object> exception,
                                                 MessageLocation* location);
  
    // Out of resource exception helpers.
    Object StackOverflow();
    Object TerminateExecution();
    void CancelTerminateExecution();
  
    void RequestInterrupt(InterruptCallback callback, void* data);
    void InvokeApiInterruptCallbacks();
  
    // Administration
    void Iterate(RootVisitor* v);
    void Iterate(RootVisitor* v, ThreadLocalTop* t);
    char* Iterate(RootVisitor* v, char* t);
    void IterateThread(ThreadVisitor* v, char* t);
  
    // Returns the current native context.
    inline Handle<NativeContext> native_context();
    inline NativeContext raw_native_context();
  
    Handle<Context> GetIncumbentContext();
  
    void RegisterTryCatchHandler(v8::TryCatch* that);
    void UnregisterTryCatchHandler(v8::TryCatch* that);
  
    char* ArchiveThread(char* to);
    char* RestoreThread(char* from);
  
    static const int kUC16AlphabetSize = 256;  // See StringSearchBase.
    static const int kBMMaxShift = 250;        // See StringSearchBase.
  
    // Accessors.
  #define GLOBAL_ACCESSOR(type, name, initialvalue)                \
    inline type name() const {                                     \
      DCHECK(OFFSET_OF(Isolate, name##_) == name##_debug_offset_); \
      return name##_;                                              \
    }                                                              \
    inline void set_##name(type value) {                           \
      DCHECK(OFFSET_OF(Isolate, name##_) == name##_debug_offset_); \
      name##_ = value;                                             \
    }
    ISOLATE_INIT_LIST(GLOBAL_ACCESSOR)
  #undef GLOBAL_ACCESSOR
  
  #define GLOBAL_ARRAY_ACCESSOR(type, name, length)                \
    inline type* name() {                                          \
      DCHECK(OFFSET_OF(Isolate, name##_) == name##_debug_offset_); \
      return &(name##_)[0];                                        \
    }
    ISOLATE_INIT_ARRAY_LIST(GLOBAL_ARRAY_ACCESSOR)
  #undef GLOBAL_ARRAY_ACCESSOR
  
  #define NATIVE_CONTEXT_FIELD_ACCESSOR(index, type, name) \
    inline Handle<type> name();                            \
    inline bool is_##name(type value);
    NATIVE_CONTEXT_FIELDS(NATIVE_CONTEXT_FIELD_ACCESSOR)
  #undef NATIVE_CONTEXT_FIELD_ACCESSOR
  
    Bootstrapper* bootstrapper() { return bootstrapper_; }
    // Use for updating counters on a foreground thread.
    Counters* counters() { return async_counters().get(); }
    // Use for updating counters on a background thread.
    const std::shared_ptr<Counters>& async_counters() {
      // Make sure InitializeCounters() has been called.
      DCHECK_NOT_NULL(async_counters_.get());
      return async_counters_;
    }
    const std::shared_ptr<metrics::Recorder>& metrics_recorder() {
      return metrics_recorder_;
    }
    RuntimeProfiler* runtime_profiler() { return runtime_profiler_; }
    CompilationCache* compilation_cache() { return compilation_cache_; }
    Logger* logger() {
      // Call InitializeLoggingAndCounters() if logging is needed before
      // the isolate is fully initialized.
      DCHECK_NOT_NULL(logger_);
      return logger_;
    }
    StackGuard* stack_guard() { return isolate_data()->stack_guard(); }
    Heap* heap() { return &heap_; }
    ReadOnlyHeap* read_only_heap() const { return read_only_heap_; }
    static Isolate* FromHeap(Heap* heap) {
      return reinterpret_cast<Isolate*>(reinterpret_cast<Address>(heap) -
                                        OFFSET_OF(Isolate, heap_));
    }
  
    const IsolateData* isolate_data() const { return &isolate_data_; }
    IsolateData* isolate_data() { return &isolate_data_; }
  
    // Generated code can embed this address to get access to the isolate-specific
    // data (for example, roots, external references, builtins, etc.).
    // The kRootRegister is set to this value.
    Address isolate_root() const { return isolate_data()->isolate_root(); }
    static size_t isolate_root_bias() {
      return OFFSET_OF(Isolate, isolate_data_) + IsolateData::kIsolateRootBias;
    }
    static Isolate* FromRootAddress(Address isolate_root) {
      return reinterpret_cast<Isolate*>(isolate_root - isolate_root_bias());
    }
  
    RootsTable& roots_table() { return isolate_data()->roots(); }
    const RootsTable& roots_table() const { return isolate_data()->roots(); }
  
    // A sub-region of the Isolate object that has "predictable" layout which
    // depends only on the pointer size and therefore it's guaranteed that there
    // will be no compatibility issues because of different compilers used for
    // snapshot generator and actual V8 code.
    // Thus, kRootRegister may be used to address any location that falls into
    // this region.
    // See IsolateData::AssertPredictableLayout() for details.
    base::AddressRegion root_register_addressable_region() const {
      return base::AddressRegion(reinterpret_cast<Address>(&isolate_data_),
                                 sizeof(IsolateData));
    }
  
    Object root(RootIndex index) { return Object(roots_table()[index]); }
  
    Handle<Object> root_handle(RootIndex index) {
      return Handle<Object>(&roots_table()[index]);
    }
  
    ExternalReferenceTable* external_reference_table() {
      DCHECK(isolate_data()->external_reference_table()->is_initialized());
      return isolate_data()->external_reference_table();
    }
  
    Address* builtin_entry_table() { return isolate_data_.builtin_entry_table(); }
    V8_INLINE Address* builtins_table() { return isolate_data_.builtins(); }
  
    bool IsBuiltinsTableHandleLocation(Address* handle_location);
  
    StubCache* load_stub_cache() { return load_stub_cache_; }
    StubCache* store_stub_cache() { return store_stub_cache_; }
    Deoptimizer* GetAndClearCurrentDeoptimizer() {
      Deoptimizer* result = current_deoptimizer_;
      CHECK_NOT_NULL(result);
      current_deoptimizer_ = nullptr;
      return result;
    }
    void set_current_deoptimizer(Deoptimizer* deoptimizer) {
      DCHECK_NULL(current_deoptimizer_);
      DCHECK_NOT_NULL(deoptimizer);
      current_deoptimizer_ = deoptimizer;
    }
    bool deoptimizer_lazy_throw() const { return deoptimizer_lazy_throw_; }
    void set_deoptimizer_lazy_throw(bool value) {
      deoptimizer_lazy_throw_ = value;
    }
    void InitializeThreadLocal();
    ThreadLocalTop* thread_local_top() {
      return &isolate_data_.thread_local_top_;
    }
    ThreadLocalTop const* thread_local_top() const {
      return &isolate_data_.thread_local_top_;
    }
  
    static uint32_t thread_in_wasm_flag_address_offset() {
      // For WebAssembly trap handlers there is a flag in thread-local storage
      // which indicates that the executing thread executes WebAssembly code. To
      // access this flag directly from generated code, we store a pointer to the
      // flag in ThreadLocalTop in thread_in_wasm_flag_address_. This function
      // here returns the offset of that member from {isolate_root()}.
      return static_cast<uint32_t>(
          OFFSET_OF(Isolate, thread_local_top()->thread_in_wasm_flag_address_) -
          isolate_root_bias());
    }
  
    MaterializedObjectStore* materialized_object_store() {
      return materialized_object_store_;
    }
  
    DescriptorLookupCache* descriptor_lookup_cache() {
      return descriptor_lookup_cache_;
    }
  
    HandleScopeData* handle_scope_data() { return &handle_scope_data_; }
  
    HandleScopeImplementer* handle_scope_implementer() {
      DCHECK(handle_scope_implementer_);
      return handle_scope_implementer_;
    }
  
    UnicodeCache* unicode_cache() { return unicode_cache_; }
  
    InnerPointerToCodeCache* inner_pointer_to_code_cache() {
      return inner_pointer_to_code_cache_;
    }
  
    GlobalHandles* global_handles() { return global_handles_; }
  
    EternalHandles* eternal_handles() { return eternal_handles_; }
  
    ThreadManager* thread_manager() { return thread_manager_; }
  
  #ifndef V8_INTL_SUPPORT
    unibrow::Mapping<unibrow::Ecma262UnCanonicalize>* jsregexp_uncanonicalize() {
      return &jsregexp_uncanonicalize_;
    }
  
    unibrow::Mapping<unibrow::CanonicalizationRange>* jsregexp_canonrange() {
      return &jsregexp_canonrange_;
    }
  
    unibrow::Mapping<unibrow::Ecma262Canonicalize>*
    regexp_macro_assembler_canonicalize() {
      return &regexp_macro_assembler_canonicalize_;
    }
  #endif  // !V8_INTL_SUPPORT
  
    RuntimeState* runtime_state() { return &runtime_state_; }
  
    Builtins* builtins() { return &builtins_; }
  
    RegExpStack* regexp_stack() { return regexp_stack_; }
  
    size_t total_regexp_code_generated() { return total_regexp_code_generated_; }
    void IncreaseTotalRegexpCodeGenerated(Handle<HeapObject> code);
  
    std::vector<int>* regexp_indices() { return &regexp_indices_; }
  
    Debug* debug() { return debug_; }
  
    void* is_profiling_address() { return &is_profiling_; }
  
    bool is_profiling() const {
      return is_profiling_.load(std::memory_order_relaxed);
    }
  
    void set_is_profiling(bool enabled) {
      is_profiling_.store(enabled, std::memory_order_relaxed);
    }
  
    CodeEventDispatcher* code_event_dispatcher() const {
      return code_event_dispatcher_.get();
    }
    HeapProfiler* heap_profiler() const { return heap_profiler_; }
  
  #ifdef DEBUG
    static size_t non_disposed_isolates() { return non_disposed_isolates_; }
  #endif
  
    v8::internal::Factory* factory() {
      // Upcast to the privately inherited base-class using c-style casts to avoid
      // undefined behavior (as static_cast cannot cast across private bases).
      // NOLINTNEXTLINE (google-readability-casting)
      return (v8::internal::Factory*)this;  // NOLINT(readability/casting)
    }
  
    static const int kJSRegexpStaticOffsetsVectorSize = 128;
  
    THREAD_LOCAL_TOP_ACCESSOR(ExternalCallbackScope*, external_callback_scope)
  
    THREAD_LOCAL_TOP_ACCESSOR(StateTag, current_vm_state)
  
    void SetData(uint32_t slot, void* data) {
      DCHECK_LT(slot, Internals::kNumIsolateDataSlots);
      isolate_data_.embedder_data_[slot] = data;
    }
    void* GetData(uint32_t slot) {
      DCHECK_LT(slot, Internals::kNumIsolateDataSlots);
      return isolate_data_.embedder_data_[slot];
    }
  
    bool serializer_enabled() const { return serializer_enabled_; }
  
    void enable_serializer() { serializer_enabled_ = true; }
  
    bool snapshot_available() const {
      return snapshot_blob_ != nullptr && snapshot_blob_->raw_size != 0;
    }
  
    bool IsDead() { return has_fatal_error_; }
    void SignalFatalError() { has_fatal_error_ = true; }
  
    bool use_optimizer();
  
    bool initialized_from_snapshot() { return initialized_from_snapshot_; }
  
    bool NeedsSourcePositionsForProfiling() const;
  
    bool NeedsDetailedOptimizedCodeLineInfo() const;
  
    bool is_best_effort_code_coverage() const {
      return code_coverage_mode() == debug::CoverageMode::kBestEffort;
    }
  
    bool is_precise_count_code_coverage() const {
      return code_coverage_mode() == debug::CoverageMode::kPreciseCount;
    }
  
    bool is_precise_binary_code_coverage() const {
      return code_coverage_mode() == debug::CoverageMode::kPreciseBinary;
    }
  
    bool is_block_count_code_coverage() const {
      return code_coverage_mode() == debug::CoverageMode::kBlockCount;
    }
  
    bool is_block_binary_code_coverage() const {
      return code_coverage_mode() == debug::CoverageMode::kBlockBinary;
    }
  
    bool is_block_code_coverage() const {
      return is_block_count_code_coverage() || is_block_binary_code_coverage();
    }
  
    bool is_binary_code_coverage() const {
      return is_precise_binary_code_coverage() || is_block_binary_code_coverage();
    }
  
    bool is_count_code_coverage() const {
      return is_precise_count_code_coverage() || is_block_count_code_coverage();
    }
  
    bool is_collecting_type_profile() const {
      return type_profile_mode() == debug::TypeProfileMode::kCollect;
    }
  
    // Collect feedback vectors with data for code coverage or type profile.
    // Reset the list, when both code coverage and type profile are not
    // needed anymore. This keeps many feedback vectors alive, but code
    // coverage or type profile are used for debugging only and increase in
    // memory usage is expected.
    void SetFeedbackVectorsForProfilingTools(Object value);
  
    void MaybeInitializeVectorListFromHeap();
  
    double time_millis_since_init() {
      return heap_.MonotonicallyIncreasingTimeInMs() - time_millis_at_init_;
    }
  
    DateCache* date_cache() { return date_cache_; }
  
    void set_date_cache(DateCache* date_cache);
  
  #ifdef V8_INTL_SUPPORT
  
    const std::string& default_locale() { return default_locale_; }
  
    void ResetDefaultLocale() { default_locale_.clear(); }
  
    void set_default_locale(const std::string& locale) {
      DCHECK_EQ(default_locale_.length(), 0);
      default_locale_ = locale;
    }
  
    // enum to access the icu object cache.
    enum class ICUObjectCacheType{
        kDefaultCollator, kDefaultNumberFormat, kDefaultSimpleDateFormat,
        kDefaultSimpleDateFormatForTime, kDefaultSimpleDateFormatForDate};
  
    icu::UMemory* get_cached_icu_object(ICUObjectCacheType cache_type);
    void set_icu_object_in_cache(ICUObjectCacheType cache_type,
                                 std::shared_ptr<icu::UMemory> obj);
    void clear_cached_icu_object(ICUObjectCacheType cache_type);
    void ClearCachedIcuObjects();
  
  #endif  // V8_INTL_SUPPORT
  
    enum class KnownPrototype { kNone, kObject, kArray, kString };
  
    KnownPrototype IsArrayOrObjectOrStringPrototype(Object object);
  
    // On intent to set an element in object, make sure that appropriate
    // notifications occur if the set is on the elements of the array or
    // object prototype. Also ensure that changes to prototype chain between
    // Array and Object fire notifications.
    void UpdateNoElementsProtectorOnSetElement(Handle<JSObject> object);
    void UpdateNoElementsProtectorOnSetLength(Handle<JSObject> object) {
      UpdateNoElementsProtectorOnSetElement(object);
    }
    void UpdateNoElementsProtectorOnSetPrototype(Handle<JSObject> object) {
      UpdateNoElementsProtectorOnSetElement(object);
    }
    void UpdateNoElementsProtectorOnNormalizeElements(Handle<JSObject> object) {
      UpdateNoElementsProtectorOnSetElement(object);
    }
  
    // Returns true if array is the initial array prototype in any native context.
    bool IsAnyInitialArrayPrototype(Handle<JSArray> array);
  
    std::unique_ptr<PersistentHandles> NewPersistentHandles();
  
    PersistentHandlesList* persistent_handles_list() {
      return persistent_handles_list_.get();
    }
  
  #ifdef DEBUG
    bool IsDeferredHandle(Address* location);
  #endif  // DEBUG
  
    bool concurrent_recompilation_enabled() {
      // Thread is only available with flag enabled.
      DCHECK(optimizing_compile_dispatcher_ == nullptr ||
             FLAG_concurrent_recompilation);
      return optimizing_compile_dispatcher_ != nullptr;
    }
  
    OptimizingCompileDispatcher* optimizing_compile_dispatcher() {
      return optimizing_compile_dispatcher_;
    }
    // Flushes all pending concurrent optimzation jobs from the optimizing
    // compile dispatcher's queue.
    void AbortConcurrentOptimization(BlockingBehavior blocking_behavior);
  
    int id() const { return id_; }
  
    CompilationStatistics* GetTurboStatistics();
    CodeTracer* GetCodeTracer();
  
    void DumpAndResetStats();
  
    void* stress_deopt_count_address() { return &stress_deopt_count_; }
  
    void set_force_slow_path(bool v) { force_slow_path_ = v; }
    bool force_slow_path() const { return force_slow_path_; }
    bool* force_slow_path_address() { return &force_slow_path_; }
  
    DebugInfo::ExecutionMode* debug_execution_mode_address() {
      return &debug_execution_mode_;
    }
  
    base::RandomNumberGenerator* random_number_generator();
  
    base::RandomNumberGenerator* fuzzer_rng();
  
    // Generates a random number that is non-zero when masked
    // with the provided mask.
    int GenerateIdentityHash(uint32_t mask);
  
    // Given an address occupied by a live code object, return that object.
    Code FindCodeObject(Address a);
  
    int NextOptimizationId() {
      int id = next_optimization_id_++;
      if (!Smi::IsValid(next_optimization_id_)) {
        next_optimization_id_ = 0;
      }
      return id;
    }
  
    void AddNearHeapLimitCallback(v8::NearHeapLimitCallback, void* data);
    void RemoveNearHeapLimitCallback(v8::NearHeapLimitCallback callback,
                                     size_t heap_limit);
    void AddCallCompletedCallback(CallCompletedCallback callback);
    void RemoveCallCompletedCallback(CallCompletedCallback callback);
    void FireCallCompletedCallback(MicrotaskQueue* microtask_queue);
  
    void AddBeforeCallEnteredCallback(BeforeCallEnteredCallback callback);
    void RemoveBeforeCallEnteredCallback(BeforeCallEnteredCallback callback);
    inline void FireBeforeCallEnteredCallback();
  
    void SetPromiseRejectCallback(PromiseRejectCallback callback);
    void ReportPromiseReject(Handle<JSPromise> promise, Handle<Object> value,
                             v8::PromiseRejectEvent event);
  
    void SetTerminationOnExternalTryCatch();
  
    Handle<Symbol> SymbolFor(RootIndex dictionary_index, Handle<String> name,
                             bool private_symbol);
  
    void SetUseCounterCallback(v8::Isolate::UseCounterCallback callback);
    void CountUsage(v8::Isolate::UseCounterFeature feature);
  
    static std::string GetTurboCfgFileName(Isolate* isolate);
  
    int GetNextScriptId();
  
  #if V8_SFI_HAS_UNIQUE_ID
    int GetNextUniqueSharedFunctionInfoId() {
      int current_id = next_unique_sfi_id_.load(std::memory_order_relaxed);
      int next_id;
      do {
        if (current_id >= Smi::kMaxValue) {
          next_id = 0;
        } else {
          next_id = current_id + 1;
        }
      } while (!next_unique_sfi_id_.compare_exchange_weak(
          current_id, next_id, std::memory_order_relaxed));
      return current_id;
    }
  #endif
  
    Address promise_hook_address() {
      return reinterpret_cast<Address>(&promise_hook_);
    }
  
    Address async_event_delegate_address() {
      return reinterpret_cast<Address>(&async_event_delegate_);
    }
  
    Address promise_hook_or_async_event_delegate_address() {
      return reinterpret_cast<Address>(&promise_hook_or_async_event_delegate_);
    }
  
    Address promise_hook_or_debug_is_active_or_async_event_delegate_address() {
      return reinterpret_cast<Address>(
          &promise_hook_or_debug_is_active_or_async_event_delegate_);
    }
  
    Address handle_scope_implementer_address() {
      return reinterpret_cast<Address>(&handle_scope_implementer_);
    }
  
    void SetAtomicsWaitCallback(v8::Isolate::AtomicsWaitCallback callback,
                                void* data);
    void RunAtomicsWaitCallback(v8::Isolate::AtomicsWaitEvent event,
                                Handle<JSArrayBuffer> array_buffer,
                                size_t offset_in_bytes, int64_t value,
                                double timeout_in_ms,
                                AtomicsWaitWakeHandle* stop_handle);
  
    void SetPromiseHook(PromiseHook hook);
    void RunPromiseHook(PromiseHookType type, Handle<JSPromise> promise,
                        Handle<Object> parent);
    void PromiseHookStateUpdated();
  
    void AddDetachedContext(Handle<Context> context);
    void CheckDetachedContextsAfterGC();
  
    void AddSharedWasmMemory(Handle<WasmMemoryObject> memory_object);
  
    std::vector<Object>* startup_object_cache() { return &startup_object_cache_; }
  
    bool IsGeneratingEmbeddedBuiltins() const {
      return builtins_constants_table_builder() != nullptr;
    }
  
    BuiltinsConstantsTableBuilder* builtins_constants_table_builder() const {
      return builtins_constants_table_builder_;
    }
  
    // Hashes bits of the Isolate that are relevant for embedded builtins. In
    // particular, the embedded blob requires builtin Code object layout and the
    // builtins constants table to remain unchanged from build-time.
    size_t HashIsolateForEmbeddedBlob();
  
    static const uint8_t* CurrentEmbeddedBlobCode();
    static uint32_t CurrentEmbeddedBlobCodeSize();
    static const uint8_t* CurrentEmbeddedBlobMetadata();
    static uint32_t CurrentEmbeddedBlobMetadataSize();
    static bool CurrentEmbeddedBlobIsBinaryEmbedded();
  
    // These always return the same result as static methods above, but don't
    // access the global atomic variable (and thus *might be* slightly faster).
    const uint8_t* embedded_blob_code() const;
    uint32_t embedded_blob_code_size() const;
    const uint8_t* embedded_blob_metadata() const;
    uint32_t embedded_blob_metadata_size() const;
  
    void set_array_buffer_allocator(v8::ArrayBuffer::Allocator* allocator) {
      array_buffer_allocator_ = allocator;
    }
    v8::ArrayBuffer::Allocator* array_buffer_allocator() const {
      return array_buffer_allocator_;
    }
  
    void set_array_buffer_allocator_shared(
        std::shared_ptr<v8::ArrayBuffer::Allocator> allocator) {
      array_buffer_allocator_shared_ = std::move(allocator);
    }
    std::shared_ptr<v8::ArrayBuffer::Allocator> array_buffer_allocator_shared()
        const {
      return array_buffer_allocator_shared_;
    }
  
    FutexWaitListNode* futex_wait_list_node() { return &futex_wait_list_node_; }
  
    CancelableTaskManager* cancelable_task_manager() {
      return cancelable_task_manager_;
    }
  
    const AstStringConstants* ast_string_constants() const {
      return ast_string_constants_;
    }
  
    interpreter::Interpreter* interpreter() const { return interpreter_; }
  
    compiler::PerIsolateCompilerCache* compiler_cache() const {
      return compiler_cache_;
    }
    void set_compiler_utils(compiler::PerIsolateCompilerCache* cache,
                            Zone* zone) {
      compiler_cache_ = cache;
      compiler_zone_ = zone;
    }
  
    AccountingAllocator* allocator() { return allocator_; }
  
    CompilerDispatcher* compiler_dispatcher() const {
      return compiler_dispatcher_;
    }
  
    bool IsInAnyContext(Object object, uint32_t index);
  
    void ClearKeptObjects();
  
    void SetHostImportModuleDynamicallyCallback(
        HostImportModuleDynamicallyCallback callback);
    MaybeHandle<JSPromise> RunHostImportModuleDynamicallyCallback(
        Handle<Script> referrer, Handle<Object> specifier);
  
    void SetHostInitializeImportMetaObjectCallback(
        HostInitializeImportMetaObjectCallback callback);
    MaybeHandle<JSObject> RunHostInitializeImportMetaObjectCallback(
        Handle<SourceTextModule> module);
  
    void RegisterEmbeddedFileWriter(EmbeddedFileWriterInterface* writer) {
      embedded_file_writer_ = writer;
    }
  
    int LookupOrAddExternallyCompiledFilename(const char* filename);
    const char* GetExternallyCompiledFilename(int index) const;
    int GetExternallyCompiledFilenameCount() const;
    // PrepareBuiltinSourcePositionMap is necessary in order to preserve the
    // builtin source positions before the corresponding code objects are
    // replaced with trampolines. Those source positions are used to
    // annotate the builtin blob with debugging information.
    void PrepareBuiltinSourcePositionMap();
  
    // Store the position of the labels that will be used in the list of allowed
    // return addresses.
    void PrepareBuiltinLabelInfoMap();
  
  #if defined(V8_OS_WIN64)
    void SetBuiltinUnwindData(
        int builtin_index,
        const win64_unwindinfo::BuiltinUnwindInfo& unwinding_info);
  #endif  // V8_OS_WIN64
  
    void SetPrepareStackTraceCallback(PrepareStackTraceCallback callback);
    MaybeHandle<Object> RunPrepareStackTraceCallback(Handle<Context>,
                                                     Handle<JSObject> Error,
                                                     Handle<JSArray> sites);
    bool HasPrepareStackTraceCallback() const;
  
    void SetAddCrashKeyCallback(AddCrashKeyCallback callback);
    void AddCrashKey(CrashKeyId id, const std::string& value) {
      if (add_crash_key_callback_) {
        add_crash_key_callback_(id, value);
      }
    }
  
    void SetRAILMode(RAILMode rail_mode);
  
    RAILMode rail_mode() { return rail_mode_.load(); }
  
    double LoadStartTimeMs();
  
    void IsolateInForegroundNotification();
  
    void IsolateInBackgroundNotification();
  
    bool IsIsolateInBackground() { return is_isolate_in_background_; }
  
    void EnableMemorySavingsMode() { memory_savings_mode_active_ = true; }
  
    void DisableMemorySavingsMode() { memory_savings_mode_active_ = false; }
  
    bool IsMemorySavingsModeActive() { return memory_savings_mode_active_; }
  
    PRINTF_FORMAT(2, 3) void PrintWithTimestamp(const char* format, ...);
  
    void set_allow_atomics_wait(bool set) { allow_atomics_wait_ = set; }
    bool allow_atomics_wait() { return allow_atomics_wait_; }
  
    // Register a finalizer to be called at isolate teardown.
    void RegisterManagedPtrDestructor(ManagedPtrDestructor* finalizer);
  
    // Removes a previously-registered shared object finalizer.
    void UnregisterManagedPtrDestructor(ManagedPtrDestructor* finalizer);
  
    size_t elements_deletion_counter() { return elements_deletion_counter_; }
    void set_elements_deletion_counter(size_t value) {
      elements_deletion_counter_ = value;
    }
  
    wasm::WasmEngine* wasm_engine() const { return wasm_engine_.get(); }
    void SetWasmEngine(std::shared_ptr<wasm::WasmEngine> engine);
  
    const v8::Context::BackupIncumbentScope* top_backup_incumbent_scope() const {
      return top_backup_incumbent_scope_;
    }
    void set_top_backup_incumbent_scope(
        const v8::Context::BackupIncumbentScope* top_backup_incumbent_scope) {
      top_backup_incumbent_scope_ = top_backup_incumbent_scope;
    }
  
    void SetIdle(bool is_idle);
  
    // Changing various modes can cause differences in generated bytecode which
    // interferes with lazy source positions, so this should be called immediately
    // before such a mode change to ensure that this cannot happen.
    void CollectSourcePositionsForAllBytecodeArrays();
  
    void AddCodeMemoryChunk(MemoryChunk* chunk);
    void RemoveCodeMemoryChunk(MemoryChunk* chunk);
    void AddCodeRange(Address begin, size_t length_in_bytes);
  
    bool RequiresCodeRange() const;
  
    static Address load_from_stack_count_address(const char* function_name);
    static Address store_to_stack_count_address(const char* function_name);
  
    v8::metrics::Recorder::ContextId GetOrRegisterRecorderContextId(
        Handle<NativeContext> context);
    MaybeLocal<v8::Context> GetContextFromRecorderContextId(
        v8::metrics::Recorder::ContextId id);
  
  #ifdef V8_HEAP_SANDBOX
    ExternalPointerTable& external_pointer_table() {
      return isolate_data_.external_pointer_table_;
    }
  
    const ExternalPointerTable& external_pointer_table() const {
      return isolate_data_.external_pointer_table_;
    }
  
    Address external_pointer_table_address() {
      return reinterpret_cast<Address>(&isolate_data_.external_pointer_table_);
    }
  #endif
  
   private:
    explicit Isolate(std::unique_ptr<IsolateAllocator> isolate_allocator);
    ~Isolate();
  
    bool Init(SnapshotData* startup_snapshot_data,
              SnapshotData* read_only_snapshot_data, bool can_rehash);
  
    void CheckIsolateLayout();
  
    void InitializeCodeRanges();
    void AddCodeMemoryRange(MemoryRange range);
  
    static void RemoveContextIdCallback(const v8::WeakCallbackInfo<void>& data);
  
    class ThreadDataTable {
     public:
      ThreadDataTable() = default;
  
      PerIsolateThreadData* Lookup(ThreadId thread_id);
      void Insert(PerIsolateThreadData* data);
      void Remove(PerIsolateThreadData* data);
      void RemoveAllThreads();
  
     private:
      struct Hasher {
        std::size_t operator()(const ThreadId& t) const {
          return std::hash<int>()(t.ToInteger());
        }
      };
  
      std::unordered_map<ThreadId, PerIsolateThreadData*, Hasher> table_;
    };
  
    // These items form a stack synchronously with threads Enter'ing and Exit'ing
    // the Isolate. The top of the stack points to a thread which is currently
    // running the Isolate. When the stack is empty, the Isolate is considered
    // not entered by any thread and can be Disposed.
    // If the same thread enters the Isolate more than once, the entry_count_
    // is incremented rather then a new item pushed to the stack.
    class EntryStackItem {
     public:
      EntryStackItem(PerIsolateThreadData* previous_thread_data,
                     Isolate* previous_isolate, EntryStackItem* previous_item)
          : entry_count(1),
            previous_thread_data(previous_thread_data),
            previous_isolate(previous_isolate),
            previous_item(previous_item) {}
  
      int entry_count;
      PerIsolateThreadData* previous_thread_data;
      Isolate* previous_isolate;
      EntryStackItem* previous_item;
  
     private:
      DISALLOW_COPY_AND_ASSIGN(EntryStackItem);
    };
  
    static base::Thread::LocalStorageKey per_isolate_thread_data_key_;
    static base::Thread::LocalStorageKey isolate_key_;
  
  #ifdef DEBUG
    static std::atomic<bool> isolate_key_created_;
  #endif
  
    void Deinit();
  
    static void SetIsolateThreadLocals(Isolate* isolate,
                                       PerIsolateThreadData* data);
  
    void MarkCompactPrologue(bool is_compacting,
                             ThreadLocalTop* archived_thread_data);
    void MarkCompactEpilogue(bool is_compacting,
                             ThreadLocalTop* archived_thread_data);
  
    void FillCache();
  
    // Propagate pending exception message to the v8::TryCatch.
    // If there is no external try-catch or message was successfully propagated,
    // then return true.
    bool PropagatePendingExceptionToExternalTryCatch();
  
    void RunPromiseHookForAsyncEventDelegate(PromiseHookType type,
                                             Handle<JSPromise> promise);
  
    const char* RAILModeName(RAILMode rail_mode) const {
      switch (rail_mode) {
        case PERFORMANCE_RESPONSE:
          return "RESPONSE";
        case PERFORMANCE_ANIMATION:
          return "ANIMATION";
        case PERFORMANCE_IDLE:
          return "IDLE";
        case PERFORMANCE_LOAD:
          return "LOAD";
      }
      return "";
    }
  
    void AddCrashKeysForIsolateAndHeapPointers();
  
    // This class contains a collection of data accessible from both C++ runtime
    // and compiled code (including assembly stubs, builtins, interpreter bytecode
    // handlers and optimized code).
    IsolateData isolate_data_;
  
    std::unique_ptr<IsolateAllocator> isolate_allocator_;
    Heap heap_;
    ReadOnlyHeap* read_only_heap_ = nullptr;
    std::shared_ptr<ReadOnlyArtifacts> artifacts_;
    std::unique_ptr<StringTable> string_table_;
  
    const int id_;
    EntryStackItem* entry_stack_ = nullptr;
    int stack_trace_nesting_level_ = 0;
    StringStream* incomplete_message_ = nullptr;
    Address isolate_addresses_[kIsolateAddressCount + 1] = {};
    Bootstrapper* bootstrapper_ = nullptr;
    RuntimeProfiler* runtime_profiler_ = nullptr;
    CompilationCache* compilation_cache_ = nullptr;
    std::shared_ptr<Counters> async_counters_;
    base::RecursiveMutex break_access_;
    base::SharedMutex transition_array_access_;
    Logger* logger_ = nullptr;
    StubCache* load_stub_cache_ = nullptr;
    StubCache* store_stub_cache_ = nullptr;
    Deoptimizer* current_deoptimizer_ = nullptr;
    bool deoptimizer_lazy_throw_ = false;
    MaterializedObjectStore* materialized_object_store_ = nullptr;
    bool capture_stack_trace_for_uncaught_exceptions_ = false;
    int stack_trace_for_uncaught_exceptions_frame_limit_ = 0;
    StackTrace::StackTraceOptions stack_trace_for_uncaught_exceptions_options_ =
        StackTrace::kOverview;
    DescriptorLookupCache* descriptor_lookup_cache_ = nullptr;
    HandleScopeData handle_scope_data_;
    HandleScopeImplementer* handle_scope_implementer_ = nullptr;
    UnicodeCache* unicode_cache_ = nullptr;
    AccountingAllocator* allocator_ = nullptr;
    InnerPointerToCodeCache* inner_pointer_to_code_cache_ = nullptr;
    GlobalHandles* global_handles_ = nullptr;
    EternalHandles* eternal_handles_ = nullptr;
    ThreadManager* thread_manager_ = nullptr;
    RuntimeState runtime_state_;
    Builtins builtins_;
    SetupIsolateDelegate* setup_delegate_ = nullptr;
  #if defined(DEBUG) || defined(VERIFY_HEAP)
    std::atomic<int> num_active_deserializers_;
  #endif
  #ifndef V8_INTL_SUPPORT
    unibrow::Mapping<unibrow::Ecma262UnCanonicalize> jsregexp_uncanonicalize_;
    unibrow::Mapping<unibrow::CanonicalizationRange> jsregexp_canonrange_;
    unibrow::Mapping<unibrow::Ecma262Canonicalize>
        regexp_macro_assembler_canonicalize_;
  #endif  // !V8_INTL_SUPPORT
    RegExpStack* regexp_stack_ = nullptr;
    std::vector<int> regexp_indices_;
    DateCache* date_cache_ = nullptr;
    base::RandomNumberGenerator* random_number_generator_ = nullptr;
    base::RandomNumberGenerator* fuzzer_rng_ = nullptr;
    std::atomic<RAILMode> rail_mode_;
    v8::Isolate::AtomicsWaitCallback atomics_wait_callback_ = nullptr;
    void* atomics_wait_callback_data_ = nullptr;
    PromiseHook promise_hook_ = nullptr;
    HostImportModuleDynamicallyCallback host_import_module_dynamically_callback_ =
        nullptr;
    HostInitializeImportMetaObjectCallback
        host_initialize_import_meta_object_callback_ = nullptr;
    base::Mutex rail_mutex_;
    double load_start_time_ms_ = 0;
  
  #ifdef V8_INTL_SUPPORT
    std::string default_locale_;
  
    struct ICUObjectCacheTypeHash {
      std::size_t operator()(ICUObjectCacheType a) const {
        return static_cast<std::size_t>(a);
      }
    };
    std::unordered_map<ICUObjectCacheType, std::shared_ptr<icu::UMemory>,
                       ICUObjectCacheTypeHash>
        icu_object_cache_;
  
  #endif  // V8_INTL_SUPPORT
  
    // true if being profiled. Causes collection of extra compile info.
    std::atomic<bool> is_profiling_{false};
  
    // Whether the isolate has been created for snapshotting.
    bool serializer_enabled_ = false;
  
    // True if fatal error has been signaled for this isolate.
    bool has_fatal_error_ = false;
  
    // True if this isolate was initialized from a snapshot.
    bool initialized_from_snapshot_ = false;
  
    // TODO(ishell): remove
    // True if ES2015 tail call elimination feature is enabled.
    bool is_tail_call_elimination_enabled_ = true;
  
    // True if the isolate is in background. This flag is used
    // to prioritize between memory usage and latency.
    bool is_isolate_in_background_ = false;
  
    // True if the isolate is in memory savings mode. This flag is used to
    // favor memory over runtime performance.
    bool memory_savings_mode_active_ = false;
  
    // Time stamp at initialization.
    double time_millis_at_init_ = 0;
  
  #ifdef DEBUG
    static std::atomic<size_t> non_disposed_isolates_;
  
    JSObject::SpillInformation js_spill_information_;
  #endif
  
    Debug* debug_ = nullptr;
    HeapProfiler* heap_profiler_ = nullptr;
    std::unique_ptr<CodeEventDispatcher> code_event_dispatcher_;
  
    const AstStringConstants* ast_string_constants_ = nullptr;
  
    interpreter::Interpreter* interpreter_ = nullptr;
  
    compiler::PerIsolateCompilerCache* compiler_cache_ = nullptr;
    // The following zone is for compiler-related objects that should live
    // through all compilations (and thus all JSHeapBroker instances).
    Zone* compiler_zone_ = nullptr;
  
    CompilerDispatcher* compiler_dispatcher_ = nullptr;
  
    using InterruptEntry = std::pair<InterruptCallback, void*>;
    std::queue<InterruptEntry> api_interrupts_queue_;
  
  #define GLOBAL_BACKING_STORE(type, name, initialvalue) type name##_;
    ISOLATE_INIT_LIST(GLOBAL_BACKING_STORE)
  #undef GLOBAL_BACKING_STORE
  
  #define GLOBAL_ARRAY_BACKING_STORE(type, name, length) type name##_[length];
    ISOLATE_INIT_ARRAY_LIST(GLOBAL_ARRAY_BACKING_STORE)
  #undef GLOBAL_ARRAY_BACKING_STORE
  
  #ifdef DEBUG
    // This class is huge and has a number of fields controlled by
    // preprocessor defines. Make sure the offsets of these fields agree
    // between compilation units.
  #define ISOLATE_FIELD_OFFSET(type, name, ignored) \
    static const intptr_t name##_debug_offset_;
    ISOLATE_INIT_LIST(ISOLATE_FIELD_OFFSET)
    ISOLATE_INIT_ARRAY_LIST(ISOLATE_FIELD_OFFSET)
  #undef ISOLATE_FIELD_OFFSET
  #endif
  
    OptimizingCompileDispatcher* optimizing_compile_dispatcher_ = nullptr;
  
    std::unique_ptr<PersistentHandlesList> persistent_handles_list_;
  
    // Counts deopt points if deopt_every_n_times is enabled.
    unsigned int stress_deopt_count_ = 0;
  
    bool force_slow_path_ = false;
  
    bool jitless_ = false;
  
    int next_optimization_id_ = 0;
  
  #if V8_SFI_HAS_UNIQUE_ID
    std::atomic<int> next_unique_sfi_id_;
  #endif
  
    // Vector of callbacks before a Call starts execution.
    std::vector<BeforeCallEnteredCallback> before_call_entered_callbacks_;
  
    // Vector of callbacks when a Call completes.
    std::vector<CallCompletedCallback> call_completed_callbacks_;
  
    v8::Isolate::UseCounterCallback use_counter_callback_ = nullptr;
  
    std::shared_ptr<metrics::Recorder> metrics_recorder_;
    uintptr_t last_recorder_context_id_ = 0;
    std::unordered_map<
        uintptr_t,
        Persistent<v8::Context, v8::CopyablePersistentTraits<v8::Context>>>
        recorder_context_id_map_;
  
    std::vector<Object> startup_object_cache_;
  
    // Used during builtins compilation to build the builtins constants table,
    // which is stored on the root list prior to serialization.
    BuiltinsConstantsTableBuilder* builtins_constants_table_builder_ = nullptr;
  
    void InitializeDefaultEmbeddedBlob();
    void CreateAndSetEmbeddedBlob();
    void TearDownEmbeddedBlob();
  
    void SetEmbeddedBlob(const uint8_t* code, uint32_t code_size,
                         const uint8_t* metadata, uint32_t metadata_size);
    void ClearEmbeddedBlob();
  
    const uint8_t* embedded_blob_code_ = nullptr;
    uint32_t embedded_blob_code_size_ = 0;
    const uint8_t* embedded_blob_metadata_ = nullptr;
    uint32_t embedded_blob_metadata_size_ = 0;
  
    v8::ArrayBuffer::Allocator* array_buffer_allocator_ = nullptr;
    std::shared_ptr<v8::ArrayBuffer::Allocator> array_buffer_allocator_shared_;
  
    FutexWaitListNode futex_wait_list_node_;
  
    CancelableTaskManager* cancelable_task_manager_ = nullptr;
  
    debug::ConsoleDelegate* console_delegate_ = nullptr;
  
    debug::AsyncEventDelegate* async_event_delegate_ = nullptr;
    bool promise_hook_or_async_event_delegate_ = false;
    bool promise_hook_or_debug_is_active_or_async_event_delegate_ = false;
    int async_task_count_ = 0;
  
    v8::Isolate::AbortOnUncaughtExceptionCallback
        abort_on_uncaught_exception_callback_ = nullptr;
  
    bool allow_atomics_wait_ = true;
  
    base::Mutex managed_ptr_destructors_mutex_;
    ManagedPtrDestructor* managed_ptr_destructors_head_ = nullptr;
  
    size_t total_regexp_code_generated_ = 0;
  
    size_t elements_deletion_counter_ = 0;
  
    std::shared_ptr<wasm::WasmEngine> wasm_engine_;
  
    std::unique_ptr<TracingCpuProfilerImpl> tracing_cpu_profiler_;
  
    EmbeddedFileWriterInterface* embedded_file_writer_ = nullptr;
  
    // The top entry of the v8::Context::BackupIncumbentScope stack.
    const v8::Context::BackupIncumbentScope* top_backup_incumbent_scope_ =
        nullptr;
  
    PrepareStackTraceCallback prepare_stack_trace_callback_ = nullptr;
  
    // TODO(kenton@cloudflare.com): This mutex can be removed if
    // thread_data_table_ is always accessed under the isolate lock. I do not
    // know if this is the case, so I'm preserving it for now.
    base::Mutex thread_data_table_mutex_;
    ThreadDataTable thread_data_table_;
  
    // A signal-safe vector of heap pages containing code. Used with the
    // v8::Unwinder API.
    std::atomic<std::vector<MemoryRange>*> code_pages_{nullptr};
    std::vector<MemoryRange> code_pages_buffer1_;
    std::vector<MemoryRange> code_pages_buffer2_;
  
    // Enables the host application to provide a mechanism for recording a
    // predefined set of data as crash keys to be used in postmortem debugging
    // in case of a crash.
    AddCrashKeyCallback add_crash_key_callback_ = nullptr;
  
    // Delete new/delete operators to ensure that Isolate::New() and
    // Isolate::Delete() are used for Isolate creation and deletion.
    void* operator new(size_t, void* ptr) { return ptr; }
  
    friend class heap::HeapTester;
    friend class TestSerializer;
  
    DISALLOW_COPY_AND_ASSIGN(Isolate);
  };
  
  #undef FIELD_ACCESSOR
  #undef THREAD_LOCAL_TOP_ACCESSOR
  
  class PromiseOnStack {
   public:
    PromiseOnStack(Handle<JSObject> promise, PromiseOnStack* prev)
        : promise_(promise), prev_(prev) {}
    Handle<JSObject> promise() { return promise_; }
    PromiseOnStack* prev() { return prev_; }
  
   private:
    Handle<JSObject> promise_;
    PromiseOnStack* prev_;
  };
  
  // SaveContext scopes save the current context on the Isolate on creation, and
  // restore it on destruction.
  class V8_EXPORT_PRIVATE SaveContext {
   public:
    explicit SaveContext(Isolate* isolate);
  
    ~SaveContext();
  
    Handle<Context> context() { return context_; }
  
    // Returns true if this save context is below a given JavaScript frame.
    bool IsBelowFrame(CommonFrame* frame);
  
   private:
    Isolate* const isolate_;
    Handle<Context> context_;
    Address c_entry_fp_;
  };
  
  // Like SaveContext, but also switches the Context to a new one in the
  // constructor.
  class V8_EXPORT_PRIVATE SaveAndSwitchContext : public SaveContext {
   public:
    SaveAndSwitchContext(Isolate* isolate, Context new_context);
  };
  
  // A scope which sets the given isolate's context to null for its lifetime to
  // ensure that code does not make assumptions on a context being available.
  class NullContextScope : public SaveAndSwitchContext {
   public:
    explicit NullContextScope(Isolate* isolate)
        : SaveAndSwitchContext(isolate, Context()) {}
  };
  
  class AssertNoContextChange {
  #ifdef DEBUG
   public:
    explicit AssertNoContextChange(Isolate* isolate);
    ~AssertNoContextChange() { DCHECK(isolate_->context() == *context_); }
  
   private:
    Isolate* isolate_;
    Handle<Context> context_;
  #else
   public:
    explicit AssertNoContextChange(Isolate* isolate) {}
  #endif
  };
  
  class ExecutionAccess {
   public:
    explicit ExecutionAccess(Isolate* isolate) : isolate_(isolate) {
      Lock(isolate);
    }
    ~ExecutionAccess() { Unlock(isolate_); }
  
    static void Lock(Isolate* isolate) { isolate->break_access()->Lock(); }
    static void Unlock(Isolate* isolate) { isolate->break_access()->Unlock(); }
  
    static bool TryLock(Isolate* isolate) {
      return isolate->break_access()->TryLock();
    }
  
   private:
    Isolate* isolate_;
  };
  
  // Support for checking for stack-overflows.
  class StackLimitCheck {
   public:
    explicit StackLimitCheck(Isolate* isolate) : isolate_(isolate) {}
  
    // Use this to check for stack-overflows in C++ code.
    bool HasOverflowed() const {
      StackGuard* stack_guard = isolate_->stack_guard();
      return GetCurrentStackPosition() < stack_guard->real_climit();
    }
  
    // Use this to check for interrupt request in C++ code.
    bool InterruptRequested() {
      StackGuard* stack_guard = isolate_->stack_guard();
      return GetCurrentStackPosition() < stack_guard->climit();
    }
  
    // Use this to check for stack-overflow when entering runtime from JS code.
    bool JsHasOverflowed(uintptr_t gap = 0) const;
  
   private:
    Isolate* isolate_;
  };
  
  #define STACK_CHECK(isolate, result_value) \
    do {                                     \
      StackLimitCheck stack_check(isolate);  \
      if (stack_check.HasOverflowed()) {     \
        isolate->StackOverflow();            \
        return result_value;                 \
      }                                      \
    } while (false)
  
  class StackTraceFailureMessage {
   public:
    explicit StackTraceFailureMessage(Isolate* isolate, void* ptr1 = nullptr,
                                      void* ptr2 = nullptr, void* ptr3 = nullptr,
                                      void* ptr4 = nullptr);
  
    V8_NOINLINE void Print() volatile;
  
    static const uintptr_t kStartMarker = 0xdecade30;
    static const uintptr_t kEndMarker = 0xdecade31;
    static const int kStacktraceBufferSize = 32 * KB;
  
    uintptr_t start_marker_ = kStartMarker;
    void* isolate_;
    void* ptr1_;
    void* ptr2_;
    void* ptr3_;
    void* ptr4_;
    void* code_objects_[4];
    char js_stack_trace_[kStacktraceBufferSize];
    uintptr_t end_marker_ = kEndMarker;
  };
  
  }  // namespace internal
  }  // namespace v8
  
  #endif  // V8_EXECUTION_ISOLATE_H_
  