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// 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_ISOLATE_H_
#define V8_ISOLATE_H_
#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.h"
#include "src/allocation.h"
#include "src/base/atomicops.h"
#include "src/base/macros.h"
#include "src/builtins/builtins.h"
#include "src/contexts.h"
#include "src/debug/debug-interface.h"
#include "src/execution.h"
#include "src/futex-emulation.h"
#include "src/globals.h"
#include "src/handles.h"
#include "src/heap/factory.h"
#include "src/heap/heap.h"
#include "src/isolate-allocator.h"
#include "src/isolate-data.h"
#include "src/messages.h"
#include "src/objects/code.h"
#include "src/objects/debug-objects.h"
#include "src/runtime/runtime.h"
#include "src/thread-id.h"
#include "src/unicode.h"
#include "unicode/uversion.h" // Define U_ICU_NAMESPACE.
namespace U_ICU_NAMESPACE {
class UObject;
} // namespace U_ICU_NAMESPACE
#endif // V8_INTL_SUPPORT
namespace v8 {
namespace base {
class RandomNumberGenerator;
namespace debug {
class ConsoleDelegate;
namespace internal {
namespace heap {
class HeapTester;
} // namespace heap
class AddressToIndexHashMap;
class AstStringConstants;
class Bootstrapper;
class BuiltinsConstantsTableBuilder;
class CancelableTaskManager;
class CodeEventDispatcher;
class CodeTracer;
class CompilationCache;
class CompilationStatistics;
class CompilerDispatcher;
class ContextSlotCache;
class Counters;
class Debug;
class DeoptimizerData;
class DescriptorLookupCache;
class EternalHandles;
class ExternalCallbackScope;
class HandleScopeImplementer;
class HeapObjectToIndexHashMap;
class HeapProfiler;
class InnerPointerToCodeCache;
class Logger;
class MaterializedObjectStore;
class Microtask;
class MicrotaskQueue;
class OptimizingCompileDispatcher;
class PromiseOnStack;
class RegExpStack;
class RootVisitor;
class RuntimeProfiler;
class SaveContext;
class SetupIsolateDelegate;
class Simulator;
class StartupDeserializer;
class StandardFrame;
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 compiler {
class PerIsolateCompilerCache;
namespace wasm {
class WasmEngine;
do { \
Isolate* __isolate__ = (isolate); \
DCHECK(!__isolate__->has_pending_exception()); \
if (__isolate__->has_scheduled_exception()) { \
return __isolate__->PromoteScheduledException(); \
} \
} while (false)
// Macros for MaybeHandle.
do { \
Isolate* __isolate__ = (isolate); \
DCHECK(!__isolate__->has_pending_exception()); \
if (__isolate__->has_scheduled_exception()) { \
__isolate__->PromoteScheduledException(); \
return value; \
} \
} while (false)
#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) {
* ...
* 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
#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 { \
Isolate* __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 { \
Isolate* __isolate__ = (isolate); \
return __isolate__->Throw<T>(__isolate__->factory()->call); \
} while (false)
#define THROW_NEW_ERROR_RETURN_FAILURE(isolate, call) \
do { \
Isolate* __isolate__ = (isolate); \
return __isolate__->Throw(*__isolate__->factory()->call); \
} while (false)
#define THROW_NEW_ERROR_RETURN_VALUE(isolate, call, value) \
do { \
Isolate* __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() {
* ...
* isolate,
* FunctionWithReturnTypeMaybeHandleX(...),
* Handle<X>());
* // code to handle non exception
* ...
* }
* Maybe<bool> Func() {
* ..
* 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
#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) {
* ...
* 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
#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() {
* ...
* isolate,
* FunctionWithReturnTypeMaybeHandleY(...),
* X);
* // code to handle non exception
* ...
* }
* If inside a function with return type Object*, use
* 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 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 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();
class ThreadLocalTop {
// Does early low-level initialization that does not depend on the
// isolate being present.
ThreadLocalTop() = default;
// Initialize the thread data.
void Initialize(Isolate*);
// Get the top C++ try catch handler or nullptr if none are registered.
// This method is not guaranteed to return an address that can be
// used for comparison with addresses into the JS stack. If such an
// address is needed, use try_catch_handler_address.
FIELD_ACCESSOR(v8::TryCatch*, try_catch_handler)
// Get the address of the top C++ try catch handler or nullptr if
// none are registered.
// This method always returns an address that can be compared to
// pointers into the JavaScript stack. When running on actual
// hardware, try_catch_handler_address and TryCatchHandler return
// the same pointer. When running on a simulator with a separate JS
// stack, try_catch_handler_address returns a JS stack address that
// corresponds to the place on the JS stack where the C++ handler
// would have been if the stack were not separate.
Address try_catch_handler_address() {
return reinterpret_cast<Address>(
void Free();
Isolate* isolate_ = nullptr;
// The context where the current execution method is created and for variable
// lookups.
// TODO(3770): This field is read/written from generated code, so it would
// be cleaner to make it an "Address raw_context_", and construct a Context
// object in the getter. Same for {pending_handler_context_} below. In the
// meantime, assert that the memory layout is the same.
STATIC_ASSERT(sizeof(Context) == kPointerSize);
Context context_;
ThreadId thread_id_ = ThreadId::Invalid();
Object* pending_exception_ = nullptr;
// Communication channel between Isolate::FindHandler and the CEntry.
Context pending_handler_context_;
Address pending_handler_entrypoint_ = kNullAddress;
Address pending_handler_constant_pool_ = kNullAddress;
Address pending_handler_fp_ = kNullAddress;
Address pending_handler_sp_ = kNullAddress;
// Communication channel between Isolate::Throw and message consumers.
bool rethrowing_message_ = false;
Object* pending_message_obj_ = nullptr;
// Use a separate value for scheduled exceptions to preserve the
// invariants that hold about pending_exception. We may want to
// unify them later.
Object* scheduled_exception_ = nullptr;
bool external_caught_exception_ = false;
SaveContext* save_context_ = nullptr;
// Stack.
// The frame pointer of the top c entry frame.
Address c_entry_fp_ = kNullAddress;
// Try-blocks are chained through the stack.
Address handler_ = kNullAddress;
// C function that was called at c entry.
Address c_function_ = kNullAddress;
// Throwing an exception may cause a Promise rejection. For this purpose
// we keep track of a stack of nested promises and the corresponding
// try-catch handlers.
PromiseOnStack* promise_on_stack_ = nullptr;
Simulator* simulator_ = nullptr;
// The stack pointer of the bottom JS entry frame.
Address js_entry_sp_ = kNullAddress;
// The external callback we're currently in.
ExternalCallbackScope* external_callback_scope_ = nullptr;
StateTag current_vm_state_ = EXTERNAL;
// Call back function to report unsafe JS accesses.
v8::FailedAccessCheckCallback failed_access_check_callback_ = nullptr;
// Address of the thread-local "thread in wasm" flag.
Address thread_in_wasm_flag_address_ = kNullAddress;
v8::TryCatch* try_catch_handler_ = nullptr;
#ifdef DEBUG
V(CommentStatistic, paged_space_comments_statistics, \
CommentStatistic::kMaxComments + 1) \
V(int, code_kind_statistics, AbstractCode::NUMBER_OF_KINDS)
/* 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)) \
typedef std::vector<HeapObject*> DebugObjectCache;
/* 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(AllowWasmCodeGenerationCallback, allow_wasm_code_gen_callback, nullptr) \
V(ExtensionCallback, wasm_module_callback, &NoExtension) \
V(ExtensionCallback, wasm_instance_callback, &NoExtension) \
V(ApiImplementationCallback, wasm_compile_streaming_callback, nullptr) \
V(WasmStreamingCallback, wasm_streaming_callback, nullptr) \
V(WasmThreadsEnabledCallback, wasm_threads_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, nullptr) \
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) \
/* true if being profiled. Causes collection of extra compile info. */ \
V(bool, is_profiling, false) \
/* 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::Coverage::Mode, code_coverage_mode, debug::Coverage::kBestEffort) \
V(debug::TypeProfile::Mode, type_profile_mode, debug::TypeProfile::kNone) \
V(int, last_stack_frame_info_id, 0) \
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)
#define THREAD_LOCAL_TOP_ACCESSOR(type, name) \
inline void set_##name(type v) { = v; } \
inline type name() const { return; }
#define THREAD_LOCAL_TOP_ADDRESS(type, name) \
type* name##_address() { return &; }
// 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 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;
// 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 {
PerIsolateThreadData(Isolate* isolate, ThreadId thread_id)
: isolate_(isolate),
prev_(nullptr) {
Isolate* isolate() const { return isolate_; }
ThreadId thread_id() const { return thread_id_; }
FIELD_ACCESSOR(uintptr_t, stack_limit)
FIELD_ACCESSOR(ThreadState*, thread_state)
FIELD_ACCESSOR(Simulator*, simulator)
bool Matches(Isolate* isolate, ThreadId thread_id) const {
return isolate_ == isolate && thread_id_.Equals(thread_id);
Isolate* isolate_;
ThreadId thread_id_;
uintptr_t stack_limit_;
ThreadState* thread_state_;
Simulator* simulator_;
PerIsolateThreadData* next_;
PerIsolateThreadData* prev_;
friend class Isolate;
friend class ThreadDataTable;
friend class EntryStackItem;
static void InitializeOncePerProcess();
// Creates Isolate object. Must be used instead of constructing Isolate with
// new operator.
static V8_EXPORT_PRIVATE Isolate* New(
IsolateAllocationMode mode = IsolateAllocationMode::kDefault);
// 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);
// Returns allocation mode of this isolate.
V8_INLINE IsolateAllocationMode isolate_allocation_mode();
// 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*>(
// Returns the isolate inside which the current thread is running or nullptr.
V8_INLINE static Isolate* TryGetCurrent() {
DCHECK_EQ(base::Relaxed_Load(&isolate_key_created_), 1);
return reinterpret_cast<Isolate*>(
// Returns the isolate inside which the current thread is running.
V8_INLINE static Isolate* Current() {
Isolate* isolate = TryGetCurrent();
return isolate;
// Get the isolate that the given HeapObject lives in, returning true on
// success. If the object is not writable (i.e. lives in read-only space),
// return false.
inline static bool FromWritableHeapObject(HeapObject* obj, Isolate** 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 Init(StartupDeserializer* des);
// 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();
// Returns the key used to store the pointer to the current isolate.
// Used internally for V8 threads that do not execute JavaScript but still
// are part of the domain of an isolate (like the context switcher).
static base::Thread::LocalStorageKey isolate_key() {
return isolate_key_;
static base::Thread::LocalStorageKey per_isolate_thread_data_key();
// Mutex for serializing access to break control structures.
base::RecursiveMutex* break_access() { return &break_access_; }
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_; }
THREAD_LOCAL_TOP_ACCESSOR(SaveContext*, save_context)
// Access to current 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);
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);
// 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_;
inline Address* handler_address() { return &thread_local_top_.handler_; }
inline Address* c_function_address() {
return &thread_local_top_.c_function_;
// 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_;
// 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<JSObject> 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.
V8_EXPORT_PRIVATE 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<Object> promise);
class ExceptionScope {
// Scope currently can only be used for regular exceptions,
// not termination exception.
inline explicit ExceptionScope(Isolate* isolate);
inline ~ExceptionScope();
Isolate* isolate_;
Handle<Object> pending_exception_;
void SetCaptureStackTraceForUncaughtExceptions(
bool capture,
int frame_limit,
StackTrace::StackTraceOptions options);
void SetAbortOnUncaughtExceptionCallback(
v8::Isolate::AbortOnUncaughtExceptionCallback callback);
enum PrintStackMode { kPrintStackConcise, kPrintStackVerbose };
void PrintCurrentStackTrace(FILE* out);
void PrintStack(StringStream* accumulator,
PrintStackMode mode = kPrintStackVerbose);
V8_EXPORT_PRIVATE 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 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;
void OnAsyncFunctionStateChanged(Handle<JSPromise> promise,
// 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 {
CatchType PredictExceptionCatcher();
V8_EXPORT_PRIVATE 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();
void ReportPendingMessagesFromJavaScript();
// Implements code shared between the two above methods
void ReportPendingMessagesImpl(bool report_externally);
// Return pending location if any or unfilled structure.
MessageLocation GetMessageLocation();
// 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);
// 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; \
#define GLOBAL_ARRAY_ACCESSOR(type, name, length) \
inline type* name() { \
DCHECK(OFFSET_OF(Isolate, name##_) == name##_debug_offset_); \
return &(name##_)[0]; \
#define NATIVE_CONTEXT_FIELD_ACCESSOR(index, type, name) \
inline Handle<type> name(); \
inline bool is_##name(type##ArgType value);
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.
return async_counters_;
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.
return logger_;
StackGuard* stack_guard() { return &stack_guard_; }
Heap* heap() { return &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;
RootsTable& roots_table() { 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_),
Object* root(RootIndex index) { return roots_table()[index]; }
Handle<Object> root_handle(RootIndex index) {
return Handle<Object>(&roots_table()[index]);
ExternalReferenceTable* external_reference_table() {
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(); }
StubCache* load_stub_cache() { return load_stub_cache_; }
StubCache* store_stub_cache() { return store_stub_cache_; }
DeoptimizerData* deoptimizer_data() { return deoptimizer_data_; }
bool deoptimizer_lazy_throw() const { return deoptimizer_lazy_throw_; }
void set_deoptimizer_lazy_throw(bool value) {
deoptimizer_lazy_throw_ = value;
ThreadLocalTop* thread_local_top() { return &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_) -
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() {
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_; }
unibrow::Mapping<unibrow::Ecma262UnCanonicalize>* jsregexp_uncanonicalize() {
return &jsregexp_uncanonicalize_;
unibrow::Mapping<unibrow::CanonicalizationRange>* jsregexp_canonrange() {
return &jsregexp_canonrange_;
RuntimeState* runtime_state() { return &runtime_state_; }
Builtins* builtins() { return &builtins_; }
regexp_macro_assembler_canonicalize() {
return &regexp_macro_assembler_canonicalize_;
RegExpStack* regexp_stack() { return regexp_stack_; }
size_t total_regexp_code_generated() { return total_regexp_code_generated_; }
void IncreaseTotalRegexpCodeGenerated(int size) {
total_regexp_code_generated_ += size;
std::vector<int>* regexp_indices() { return &regexp_indices_; }
interp_canonicalize_mapping() {
return &regexp_macro_assembler_canonicalize_;
Debug* debug() { return debug_; }
bool* is_profiling_address() { return &is_profiling_; }
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_; }
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::Coverage::kBestEffort;
bool is_precise_count_code_coverage() const {
return code_coverage_mode() == debug::Coverage::kPreciseCount;
bool is_precise_binary_code_coverage() const {
return code_coverage_mode() == debug::Coverage::kPreciseBinary;
bool is_block_count_code_coverage() const {
return code_coverage_mode() == debug::Coverage::kBlockCount;
bool is_block_binary_code_coverage() const {
return code_coverage_mode() == debug::Coverage::kBlockBinary;
bool is_block_code_coverage() const {
return is_block_count_code_coverage() || is_block_binary_code_coverage();
bool is_collecting_type_profile() const {
return type_profile_mode() == debug::TypeProfile::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);
const std::string& default_locale() { return default_locale_; }
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::UObject* get_cached_icu_object(ICUObjectCacheType cache_type);
void set_icu_object_in_cache(ICUObjectCacheType cache_type,
std::shared_ptr<icu::UObject> obj);
void clear_cached_icu_object(ICUObjectCacheType cache_type);
#endif // V8_INTL_SUPPORT
static const int kProtectorValid = 1;
static const int kProtectorInvalid = 0;
inline bool IsArrayConstructorIntact();
// The version with an explicit context parameter can be used when
// Isolate::context is not set up, e.g. when calling directly into C++ from
// CSA.
bool IsNoElementsProtectorIntact(Context context);
bool IsNoElementsProtectorIntact();
bool IsArrayOrObjectOrStringPrototype(Object* object);
inline bool IsArraySpeciesLookupChainIntact();
inline bool IsTypedArraySpeciesLookupChainIntact();
inline bool IsRegExpSpeciesLookupChainIntact();
inline bool IsPromiseSpeciesLookupChainIntact();
bool IsIsConcatSpreadableLookupChainIntact();
bool IsIsConcatSpreadableLookupChainIntact(JSReceiver receiver);
inline bool IsStringLengthOverflowIntact();
inline bool IsArrayIteratorLookupChainIntact();
// The MapIterator protector protects the original iteration behaviors of
// Map.prototype.keys(), Map.prototype.values(), and Set.prototype.entries().
// It does not protect the original iteration behavior of
// Map.prototype[Symbol.iterator](). The protector is invalidated when:
// * The 'next' property is set on an object where the property holder is the
// %MapIteratorPrototype% (e.g. because the object is that very prototype).
// * The 'Symbol.iterator' property is set on an object where the property
// holder is the %IteratorPrototype%. Note that this also invalidates the
// SetIterator protector (see below).
inline bool IsMapIteratorLookupChainIntact();
// The SetIterator protector protects the original iteration behavior of
// Set.prototype.keys(), Set.prototype.values(), Set.prototype.entries(),
// and Set.prototype[Symbol.iterator](). The protector is invalidated when:
// * The 'next' property is set on an object where the property holder is the
// %SetIteratorPrototype% (e.g. because the object is that very prototype).
// * The 'Symbol.iterator' property is set on an object where the property
// holder is the %SetPrototype% OR %IteratorPrototype%. This means that
// setting Symbol.iterator on a MapIterator object can also invalidate the
// SetIterator protector, and vice versa, setting Symbol.iterator on a
// SetIterator object can also invalidate the MapIterator. This is an over-
// approximation for the sake of simplicity.
inline bool IsSetIteratorLookupChainIntact();
// The StringIteratorProtector protects the original string iteration behavior
// for primitive strings. As long as the StringIteratorProtector is valid,
// iterating over a primitive string is guaranteed to be unobservable from
// user code and can thus be cut short. More specifically, the protector gets
// invalidated as soon as either String.prototype[Symbol.iterator] or
// String.prototype[Symbol.iterator]().next is modified. This guarantee does
// not apply to string objects (as opposed to primitives), since they could
// define their own Symbol.iterator.
// String.prototype itself does not need to be protected, since it is
// non-configurable and non-writable.
inline bool IsStringIteratorLookupChainIntact();
// Make sure we do check for detached array buffers.
inline bool IsArrayBufferDetachingIntact();
// Disable promise optimizations if promise (debug) hooks have ever been
// active.
bool IsPromiseHookProtectorIntact();
// Make sure a lookup of "resolve" on the %Promise% intrinsic object
// yeidls the initial Promise.resolve method.
bool IsPromiseResolveLookupChainIntact();
// Make sure a lookup of "then" on any JSPromise whose [[Prototype]] is the
// initial %PromisePrototype% yields the initial method. In addition this
// protector also guards the negative lookup of "then" on the intrinsic
// %ObjectPrototype%, meaning that such lookups are guaranteed to yield
// undefined without triggering any side-effects.
bool IsPromiseThenLookupChainIntact();
bool IsPromiseThenLookupChainIntact(Handle<JSReceiver> receiver);
// 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) {
void UpdateNoElementsProtectorOnSetPrototype(Handle<JSObject> object) {
void UpdateNoElementsProtectorOnNormalizeElements(Handle<JSObject> object) {
void InvalidateArrayConstructorProtector();
void InvalidateArraySpeciesProtector();
void InvalidateTypedArraySpeciesProtector();
void InvalidateRegExpSpeciesProtector();
void InvalidatePromiseSpeciesProtector();
void InvalidateIsConcatSpreadableProtector();
void InvalidateStringLengthOverflowProtector();
void InvalidateArrayIteratorProtector();
void InvalidateMapIteratorProtector();
void InvalidateSetIteratorProtector();
void InvalidateStringIteratorProtector();
void InvalidateArrayBufferDetachingProtector();
V8_EXPORT_PRIVATE void InvalidatePromiseHookProtector();
void InvalidatePromiseResolveProtector();
void InvalidatePromiseThenProtector();
// Returns true if array is the initial array prototype in any native context.
bool IsAnyInitialArrayPrototype(Handle<JSArray> array);
void IterateDeferredHandles(RootVisitor* visitor);
void LinkDeferredHandles(DeferredHandles* deferred_handles);
void UnlinkDeferredHandles(DeferredHandles* deferred_handles);
#ifdef DEBUG
bool IsDeferredHandle(Address* location);
#endif // DEBUG
bool concurrent_recompilation_enabled() {
// Thread is only available with flag enabled.
DCHECK(optimizing_compile_dispatcher_ == nullptr ||
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 static_cast<int>(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_;
V8_EXPORT_PRIVATE base::RandomNumberGenerator* random_number_generator();
V8_EXPORT_PRIVATE 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();
void AddBeforeCallEnteredCallback(BeforeCallEnteredCallback callback);
void RemoveBeforeCallEnteredCallback(BeforeCallEnteredCallback callback);
inline void FireBeforeCallEnteredCallback();
void AddMicrotasksCompletedCallback(MicrotasksCompletedCallback callback);
void RemoveMicrotasksCompletedCallback(MicrotasksCompletedCallback callback);
inline void FireMicrotasksCompletedCallback();
void SetPromiseRejectCallback(PromiseRejectCallback callback);
void ReportPromiseReject(Handle<JSPromise> promise, Handle<Object> value,
v8::PromiseRejectEvent event);
void EnqueueMicrotask(Handle<Microtask> microtask);
void RunMicrotasks();
bool IsRunningMicrotasks() const { return is_running_microtasks_; }
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 GetNextUniqueSharedFunctionInfoId() { return next_unique_sfi_id_++; }
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 default_microtask_queue_address() {
return reinterpret_cast<Address>(&default_microtask_queue_);
Address promise_hook_or_debug_is_active_or_async_event_delegate_address() {
return reinterpret_cast<Address>(
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();
std::vector<Object*>* read_only_object_cache() {
return &read_only_object_cache_;
std::vector<Object*>* partial_snapshot_cache() {
return &partial_snapshot_cache_;
// Off-heap builtins cannot embed constants within the code object itself,
// and thus need to load them from the root list.
// TODO(jgruber): Rename to IsGeneratingEmbeddedBuiltins().
bool ShouldLoadConstantsFromRootList() const {
return FLAG_embedded_builtins &&
builtins_constants_table_builder() != nullptr;
BuiltinsConstantsTableBuilder* builtins_constants_table_builder() const {
return builtins_constants_table_builder_;
static const uint8_t* CurrentEmbeddedBlob();
static uint32_t CurrentEmbeddedBlobSize();
// 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() const;
uint32_t embedded_blob_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_;
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 SetHostImportModuleDynamicallyCallback(
HostImportModuleDynamicallyCallback callback);
MaybeHandle<JSPromise> RunHostImportModuleDynamicallyCallback(
Handle<Script> referrer, Handle<Object> specifier);
void SetHostInitializeImportMetaObjectCallback(
HostInitializeImportMetaObjectCallback callback);
Handle<JSObject> RunHostInitializeImportMetaObjectCallback(
Handle<Module> module);
void SetPrepareStackTraceCallback(PrepareStackTraceCallback callback);
MaybeHandle<Object> RunPrepareStackTraceCallback(Handle<Context>,
Handle<JSObject> Error,
Handle<JSArray> sites);
bool HasPrepareStackTraceCallback() const;
void SetRAILMode(RAILMode rail_mode);
RAILMode rail_mode() { return rail_mode_.Value(); }
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);
explicit Isolate(std::unique_ptr<IsolateAllocator> isolate_allocator);
void CheckIsolateLayout();
class ThreadDataTable {
ThreadDataTable() = default;
PerIsolateThreadData* Lookup(ThreadId thread_id);
void Insert(PerIsolateThreadData* data);
void Remove(PerIsolateThreadData* data);
void RemoveAllThreads();
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 {
EntryStackItem(PerIsolateThreadData* previous_thread_data,
Isolate* previous_isolate,
EntryStackItem* previous_item)
: entry_count(1),
previous_item(previous_item) { }
int entry_count;
PerIsolateThreadData* previous_thread_data;
Isolate* previous_isolate;
EntryStackItem* previous_item;
static base::Thread::LocalStorageKey per_isolate_thread_data_key_;
static base::Thread::LocalStorageKey isolate_key_;
// A global counter for all generated Isolates, might overflow.
static base::Atomic32 isolate_counter_;
static base::Atomic32 isolate_key_created_;
void Deinit();
static void SetIsolateThreadLocals(Isolate* isolate,
PerIsolateThreadData* data);
void InitializeThreadLocal();
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 SetTerminationOnExternalTryCatch();
void RunPromiseHookForAsyncEventDelegate(PromiseHookType type,
Handle<JSPromise> promise);
const char* RAILModeName(RAILMode rail_mode) const {
switch (rail_mode) {
return "RESPONSE";
return "ANIMATION";
return "IDLE";
return "LOAD";
return "";
// 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_;
base::Atomic32 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_;
Logger* logger_ = nullptr;
StackGuard stack_guard_;
StubCache* load_stub_cache_ = nullptr;
StubCache* store_stub_cache_ = nullptr;
DeoptimizerData* deoptimizer_data_ = nullptr;
bool deoptimizer_lazy_throw_ = false;
MaterializedObjectStore* materialized_object_store_ = nullptr;
ThreadLocalTop thread_local_top_;
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_ =
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;
unibrow::Mapping<unibrow::Ecma262UnCanonicalize> jsregexp_uncanonicalize_;
unibrow::Mapping<unibrow::CanonicalizationRange> jsregexp_canonrange_;
RegExpStack* regexp_stack_ = nullptr;
std::vector<int> regexp_indices_;
DateCache* date_cache_ = nullptr;
base::RandomNumberGenerator* random_number_generator_ = nullptr;
base::RandomNumberGenerator* fuzzer_rng_ = nullptr;
base::AtomicValue<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_ =
host_initialize_import_meta_object_callback_ = nullptr;
base::Mutex rail_mutex_;
double load_start_time_ms_ = 0;
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::UObject>,
#endif // V8_INTL_SUPPORT
// 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_;
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;
Zone* compiler_zone_ = nullptr;
CompilerDispatcher* compiler_dispatcher_ = nullptr;
typedef std::pair<InterruptCallback, void*> InterruptEntry;
std::queue<InterruptEntry> api_interrupts_queue_;
#define GLOBAL_BACKING_STORE(type, name, initialvalue) \
type name##_;
#define GLOBAL_ARRAY_BACKING_STORE(type, name, length) \
type name##_[length];
#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) \
V8_EXPORT_PRIVATE static const intptr_t name##_debug_offset_;
DeferredHandles* deferred_handles_head_ = nullptr;
OptimizingCompileDispatcher* optimizing_compile_dispatcher_ = nullptr;
// Counts deopt points if deopt_every_n_times is enabled.
unsigned int stress_deopt_count_ = 0;
bool force_slow_path_ = false;
int next_optimization_id_ = 0;
int next_unique_sfi_id_ = 0;
// 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_;
// Vector of callbacks after microtasks were run.
std::vector<MicrotasksCompletedCallback> microtasks_completed_callbacks_;
bool is_running_microtasks_ = false;
v8::Isolate::UseCounterCallback use_counter_callback_ = nullptr;
std::vector<Object*> read_only_object_cache_;
std::vector<Object*> partial_snapshot_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* blob, uint32_t blob_size);
void ClearEmbeddedBlob();
const uint8_t* embedded_blob_ = nullptr;
uint32_t embedded_blob_size_ = 0;
v8::ArrayBuffer::Allocator* array_buffer_allocator_ = nullptr;
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;
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_;
// The top entry of the v8::Context::BackupIncumbentScope stack.
const v8::Context::BackupIncumbentScope* top_backup_incumbent_scope_ =
PrepareStackTraceCallback prepare_stack_trace_callback_ = nullptr;
// TODO( 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_;
// 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; }
void* operator new(size_t) = delete;
void operator delete(void*) = delete;
friend class heap::HeapTester;
friend class TestSerializer;
class PromiseOnStack {
PromiseOnStack(Handle<JSObject> promise, PromiseOnStack* prev)
: promise_(promise), prev_(prev) {}
Handle<JSObject> promise() { return promise_; }
PromiseOnStack* prev() { return prev_; }
Handle<JSObject> promise_;
PromiseOnStack* prev_;
// If the GCC version is 4.1.x or 4.2.x an additional field is added to the
// class as a work around for a bug in the generated code found with these
// versions of GCC. See V8 issue 122 for details.
class V8_EXPORT_PRIVATE SaveContext {
explicit SaveContext(Isolate* isolate);
Handle<Context> context() { return context_; }
SaveContext* prev() { return prev_; }
// Returns true if this save context is below a given JavaScript frame.
bool IsBelowFrame(StandardFrame* frame);
Isolate* const isolate_;
Handle<Context> context_;
SaveContext* const prev_;
Address c_entry_fp_;
class AssertNoContextChange {
#ifdef DEBUG
explicit AssertNoContextChange(Isolate* isolate);
~AssertNoContextChange() {
DCHECK(isolate_->context() == *context_);
Isolate* isolate_;
Handle<Context> context_;
explicit AssertNoContextChange(Isolate* isolate) { }
class ExecutionAccess {
explicit ExecutionAccess(Isolate* isolate) : isolate_(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();
Isolate* isolate_;
// Support for checking for stack-overflows.
class StackLimitCheck {
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;
Isolate* isolate_;
#define STACK_CHECK(isolate, result_value) \
do { \
StackLimitCheck stack_check(isolate); \
if (stack_check.HasOverflowed()) { \
isolate->StackOverflow(); \
return result_value; \
} \
} while (false)
// Scope intercepts only interrupt which is part of its interrupt_mask and does
// not affect other interrupts.
class InterruptsScope {
enum Mode { kPostponeInterrupts, kRunInterrupts, kNoop };
virtual ~InterruptsScope() {
if (mode_ != kNoop) stack_guard_->PopInterruptsScope();
// Find the scope that intercepts this interrupt.
// It may be outermost PostponeInterruptsScope or innermost
// SafeForInterruptsScope if any.
// Return whether the interrupt has been intercepted.
bool Intercept(StackGuard::InterruptFlag flag);
InterruptsScope(Isolate* isolate, int intercept_mask, Mode mode)
: stack_guard_(isolate->stack_guard()),
mode_(mode) {
if (mode_ != kNoop) stack_guard_->PushInterruptsScope(this);
StackGuard* stack_guard_;
int intercept_mask_;
int intercepted_flags_;
Mode mode_;
InterruptsScope* prev_;
friend class StackGuard;
// Support for temporarily postponing interrupts. When the outermost
// postpone scope is left the interrupts will be re-enabled and any
// interrupts that occurred while in the scope will be taken into
// account.
class PostponeInterruptsScope : public InterruptsScope {
PostponeInterruptsScope(Isolate* isolate,
int intercept_mask = StackGuard::ALL_INTERRUPTS)
: InterruptsScope(isolate, intercept_mask,
InterruptsScope::kPostponeInterrupts) {}
~PostponeInterruptsScope() override = default;
// Support for overriding PostponeInterruptsScope. Interrupt is not ignored if
// innermost scope is SafeForInterruptsScope ignoring any outer
// PostponeInterruptsScopes.
class SafeForInterruptsScope : public InterruptsScope {
SafeForInterruptsScope(Isolate* isolate,
int intercept_mask = StackGuard::ALL_INTERRUPTS)
: InterruptsScope(isolate, intercept_mask,
InterruptsScope::kRunInterrupts) {}
~SafeForInterruptsScope() override = default;
class StackTraceFailureMessage {
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_ISOLATE_H_