Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1152 insertions, 0 deletions

diff --git a/js/src/vm/JSContext.h b/js/src/vm/JSContext.h
new file mode 100644
index 0000000000..1801816fa0
--- /dev/null
+++ b/js/src/vm/JSContext.h
@@ -0,0 +1,1152 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* JS execution context. */
+
+#ifndef vm_JSContext_h
+#define vm_JSContext_h
+
+#include "mozilla/Maybe.h"
+#include "mozilla/MemoryReporting.h"
+
+#include "jstypes.h"  // JS_PUBLIC_API
+
+#include "builtin/AtomicsObject.h"
+#include "ds/TraceableFifo.h"
+#include "frontend/NameCollections.h"
+#include "gc/GCEnum.h"
+#include "gc/Memory.h"
+#include "irregexp/RegExpTypes.h"
+#include "jit/PcScriptCache.h"
+#include "js/ContextOptions.h"  // JS::ContextOptions
+#include "js/Exception.h"
+#include "js/GCVector.h"
+#include "js/Interrupt.h"
+#include "js/Promise.h"
+#include "js/Result.h"
+#include "js/Stack.h"  // JS::NativeStackBase, JS::NativeStackLimit
+#include "js/Utility.h"
+#include "js/Vector.h"
+#include "threading/ProtectedData.h"
+#include "util/StructuredSpewer.h"
+#include "vm/Activation.h"  // js::Activation
+#include "vm/MallocProvider.h"
+#include "vm/Runtime.h"
+#include "wasm/WasmContext.h"
+
+struct JS_PUBLIC_API JSContext;
+
+struct DtoaState;
+
+namespace js {
+
+class AutoAllocInAtomsZone;
+class AutoMaybeLeaveAtomsZone;
+class AutoRealm;
+struct PortableBaselineStack;
+
+namespace jit {
+class ICScript;
+class JitActivation;
+class JitContext;
+class DebugModeOSRVolatileJitFrameIter;
+}  // namespace jit
+
+/* Detects cycles when traversing an object graph. */
+class MOZ_RAII AutoCycleDetector {
+ public:
+  using Vector = GCVector<JSObject*, 8>;
+
+  AutoCycleDetector(JSContext* cx, HandleObject objArg)
+      : cx(cx), obj(cx, objArg), cyclic(true) {}
+
+  ~AutoCycleDetector();
+
+  bool init();
+
+  bool foundCycle() { return cyclic; }
+
+ private:
+  JSContext* cx;
+  RootedObject obj;
+  bool cyclic;
+};
+
+struct AutoResolving;
+
+class InternalJobQueue : public JS::JobQueue {
+ public:
+  explicit InternalJobQueue(JSContext* cx)
+      : queue(cx, SystemAllocPolicy()), draining_(false), interrupted_(false) {}
+  ~InternalJobQueue() = default;
+
+  // JS::JobQueue methods.
+  JSObject* getIncumbentGlobal(JSContext* cx) override;
+  bool enqueuePromiseJob(JSContext* cx, JS::HandleObject promise,
+                         JS::HandleObject job, JS::HandleObject allocationSite,
+                         JS::HandleObject incumbentGlobal) override;
+  void runJobs(JSContext* cx) override;
+  bool empty() const override;
+
+  // If we are currently in a call to runJobs(), make that call stop processing
+  // jobs once the current one finishes, and return. If we are not currently in
+  // a call to runJobs, make all future calls return immediately.
+  void interrupt() { interrupted_ = true; }
+
+  // Return the front element of the queue, or nullptr if the queue is empty.
+  // This is only used by shell testing functions.
+  JSObject* maybeFront() const;
+
+#ifdef DEBUG
+  JSObject* copyJobs(JSContext* cx);
+#endif
+
+ private:
+  using Queue = js::TraceableFifo<JSObject*, 0, SystemAllocPolicy>;
+
+  JS::PersistentRooted<Queue> queue;
+
+  // True if we are in the midst of draining jobs from this queue. We use this
+  // to avoid re-entry (nested calls simply return immediately).
+  bool draining_;
+
+  // True if we've been asked to interrupt draining jobs. Set by interrupt().
+  bool interrupted_;
+
+  class SavedQueue;
+  js::UniquePtr<JobQueue::SavedJobQueue> saveJobQueue(JSContext*) override;
+};
+
+class AutoLockScriptData;
+
+/* Thread Local Storage slot for storing the context for a thread. */
+extern MOZ_THREAD_LOCAL(JSContext*) TlsContext;
+
+#ifdef DEBUG
+JSContext* MaybeGetJSContext();
+#endif
+
+enum class InterruptReason : uint32_t {
+  MinorGC = 1 << 0,
+  MajorGC = 1 << 1,
+  AttachIonCompilations = 1 << 2,
+  CallbackUrgent = 1 << 3,
+  CallbackCanWait = 1 << 4,
+};
+
+enum class ShouldCaptureStack { Maybe, Always };
+
+} /* namespace js */
+
+/*
+ * A JSContext encapsulates the thread local state used when using the JS
+ * runtime.
+ */
+struct JS_PUBLIC_API JSContext : public JS::RootingContext,
+                                 public js::MallocProvider<JSContext> {
+  JSContext(JSRuntime* runtime, const JS::ContextOptions& options);
+  ~JSContext();
+
+  bool init();
+
+  static JSContext* from(JS::RootingContext* rcx) {
+    return static_cast<JSContext*>(rcx);
+  }
+
+ private:
+  js::UnprotectedData<JSRuntime*> runtime_;
+#ifdef DEBUG
+  js::WriteOnceData<bool> initialized_;
+#endif
+
+  js::ContextData<JS::ContextOptions> options_;
+
+  // Are we currently timing execution? This flag ensures that we do not
+  // double-count execution time in reentrant situations.
+  js::ContextData<bool> measuringExecutionTime_;
+
+  // This variable is used by the HelperThread scheduling to update the priority
+  // of task based on whether JavaScript is being executed on the main thread.
+  mozilla::Atomic<bool, mozilla::ReleaseAcquire> isExecuting_;
+
+ public:
+  // This is used by helper threads to change the runtime their context is
+  // currently operating on.
+  void setRuntime(JSRuntime* rt);
+
+  bool isMeasuringExecutionTime() const { return measuringExecutionTime_; }
+  void setIsMeasuringExecutionTime(bool value) {
+    measuringExecutionTime_ = value;
+  }
+
+  // While JSContexts are meant to be used on a single thread, this reference is
+  // meant to be shared to helper thread tasks. This is used by helper threads
+  // to change the priority of tasks based on whether JavaScript is executed on
+  // the main thread.
+  const mozilla::Atomic<bool, mozilla::ReleaseAcquire>& isExecutingRef() const {
+    return isExecuting_;
+  }
+  void setIsExecuting(bool value) { isExecuting_ = value; }
+
+#ifdef DEBUG
+  bool isInitialized() const { return initialized_; }
+#endif
+
+  template <typename T>
+  bool isInsideCurrentZone(T thing) const {
+    return thing->zoneFromAnyThread() == zone_;
+  }
+
+  template <typename T>
+  inline bool isInsideCurrentCompartment(T thing) const {
+    return thing->compartment() == compartment();
+  }
+
+  void onOutOfMemory();
+  void* onOutOfMemory(js::AllocFunction allocFunc, arena_id_t arena,
+                      size_t nbytes, void* reallocPtr = nullptr) {
+    return runtime_->onOutOfMemory(allocFunc, arena, nbytes, reallocPtr, this);
+  }
+
+  void onOverRecursed();
+
+  // Allocate a GC thing.
+  template <typename T, js::AllowGC allowGC = js::CanGC, typename... Args>
+  T* newCell(Args&&... args);
+
+  /* Clear the pending exception (if any) due to OOM. */
+  void recoverFromOutOfMemory();
+
+  void reportAllocationOverflow();
+
+  // Accessors for immutable runtime data.
+  JSAtomState& names() { return *runtime_->commonNames; }
+  js::StaticStrings& staticStrings() { return *runtime_->staticStrings; }
+  bool permanentAtomsPopulated() { return runtime_->permanentAtomsPopulated(); }
+  const js::FrozenAtomSet& permanentAtoms() {
+    return *runtime_->permanentAtoms();
+  }
+  js::WellKnownSymbols& wellKnownSymbols() {
+    return *runtime_->wellKnownSymbols;
+  }
+  js::PropertyName* emptyString() { return runtime_->emptyString; }
+  JS::GCContext* gcContext() { return runtime_->gcContext(); }
+  JS::StackKind stackKindForCurrentPrincipal();
+  JS::NativeStackLimit stackLimitForCurrentPrincipal();
+  JS::NativeStackLimit stackLimit(JS::StackKind kind) {
+    return nativeStackLimit[kind];
+  }
+  JS::NativeStackLimit stackLimitForJitCode(JS::StackKind kind);
+  size_t gcSystemPageSize() { return js::gc::SystemPageSize(); }
+
+  /*
+   * "Entering" a realm changes cx->realm (which changes cx->global). Note
+   * that this does not push an Activation so it's possible for the caller's
+   * realm to be != cx->realm(). This is not a problem since, in general, most
+   * places in the VM cannot know that they were called from script (e.g.,
+   * they may have been called through the JSAPI via JS_CallFunction) and thus
+   * cannot expect there is a scripted caller.
+   *
+   * Realms should be entered/left in a LIFO fasion. To enter a realm, code
+   * should prefer using AutoRealm over JS::EnterRealm/JS::LeaveRealm.
+   *
+   * Also note that the JIT can enter (same-compartment) realms without going
+   * through these methods - it will update cx->realm_ directly.
+   */
+ private:
+  inline void setRealm(JS::Realm* realm);
+  inline void enterRealm(JS::Realm* realm);
+
+  inline void enterAtomsZone();
+  inline void leaveAtomsZone(JS::Realm* oldRealm);
+  inline void setZone(js::Zone* zone);
+
+  friend class js::AutoAllocInAtomsZone;
+  friend class js::AutoMaybeLeaveAtomsZone;
+  friend class js::AutoRealm;
+
+ public:
+  inline void enterRealmOf(JSObject* target);
+  inline void enterRealmOf(JSScript* target);
+  inline void enterRealmOf(js::Shape* target);
+  inline void enterNullRealm();
+
+  inline void setRealmForJitExceptionHandler(JS::Realm* realm);
+
+  inline void leaveRealm(JS::Realm* oldRealm);
+
+  // Threads may freely access any data in their realm, compartment and zone.
+  JS::Compartment* compartment() const {
+    return realm_ ? JS::GetCompartmentForRealm(realm_) : nullptr;
+  }
+
+  JS::Realm* realm() const { return realm_; }
+
+#ifdef DEBUG
+  bool inAtomsZone() const;
+#endif
+
+  JS::Zone* zone() const {
+    MOZ_ASSERT_IF(!realm() && zone_, inAtomsZone());
+    MOZ_ASSERT_IF(realm(), js::GetRealmZone(realm()) == zone_);
+    return zone_;
+  }
+
+  // For JIT use.
+  static size_t offsetOfZone() { return offsetof(JSContext, zone_); }
+
+  // Current global. This is only safe to use within the scope of the
+  // AutoRealm from which it's called.
+  inline js::Handle<js::GlobalObject*> global() const;
+
+  js::AtomsTable& atoms() { return runtime_->atoms(); }
+
+  js::SymbolRegistry& symbolRegistry() { return runtime_->symbolRegistry(); }
+
+  // Methods to access other runtime data that checks locking internally.
+  js::gc::AtomMarkingRuntime& atomMarking() { return runtime_->gc.atomMarking; }
+  void markAtom(JSAtom* atom) { atomMarking().markAtom(this, atom); }
+  void markAtom(JS::Symbol* symbol) { atomMarking().markAtom(this, symbol); }
+  void markId(jsid id) { atomMarking().markId(this, id); }
+  void markAtomValue(const js::Value& value) {
+    atomMarking().markAtomValue(this, value);
+  }
+
+  // Interface for recording telemetry metrics.
+  js::Metrics metrics() { return js::Metrics(runtime_); }
+
+  JSRuntime* runtime() { return runtime_; }
+  const JSRuntime* runtime() const { return runtime_; }
+
+  static size_t offsetOfRealm() { return offsetof(JSContext, realm_); }
+
+  friend class JS::AutoSaveExceptionState;
+  friend class js::jit::DebugModeOSRVolatileJitFrameIter;
+  friend void js::ReportOutOfMemory(JSContext*);
+  friend void js::ReportOverRecursed(JSContext*);
+  friend void js::ReportOversizedAllocation(JSContext*, const unsigned);
+
+ public:
+  /**
+   * Intentionally awkward signpost method that is stationed on the
+   * boundary between Result-using and non-Result-using code.
+   */
+  template <typename V, typename E>
+  bool resultToBool(const JS::Result<V, E>& result) {
+    return result.isOk();
+  }
+
+  template <typename V, typename E>
+  V* resultToPtr(JS::Result<V*, E>& result) {
+    return result.isOk() ? result.unwrap() : nullptr;
+  }
+
+  mozilla::GenericErrorResult<JS::OOM> alreadyReportedOOM();
+  mozilla::GenericErrorResult<JS::Error> alreadyReportedError();
+
+  /*
+   * Points to the most recent JitActivation pushed on the thread.
+   * See JitActivation constructor in vm/Stack.cpp
+   */
+  js::ContextData<js::jit::JitActivation*> jitActivation;
+
+  // Shim for V8 interfaces used by irregexp code
+  js::ContextData<js::irregexp::Isolate*> isolate;
+
+  /*
+   * Points to the most recent activation running on the thread.
+   * See Activation comment in vm/Stack.h.
+   */
+  js::ContextData<js::Activation*> activation_;
+
+  /*
+   * Points to the most recent profiling activation running on the
+   * thread.
+   */
+  js::Activation* volatile profilingActivation_;
+
+ public:
+  js::Activation* activation() const { return activation_; }
+  static size_t offsetOfActivation() {
+    return offsetof(JSContext, activation_);
+  }
+
+  js::Activation* profilingActivation() const { return profilingActivation_; }
+  static size_t offsetOfProfilingActivation() {
+    return offsetof(JSContext, profilingActivation_);
+  }
+
+  static size_t offsetOfJitActivation() {
+    return offsetof(JSContext, jitActivation);
+  }
+
+#ifdef DEBUG
+  static size_t offsetOfInUnsafeCallWithABI() {
+    return offsetof(JSContext, inUnsafeCallWithABI);
+  }
+#endif
+
+  static size_t offsetOfInlinedICScript() {
+    return offsetof(JSContext, inlinedICScript_);
+  }
+
+ public:
+  js::InterpreterStack& interpreterStack() {
+    return runtime()->interpreterStack();
+  }
+#ifdef ENABLE_PORTABLE_BASELINE_INTERP
+  js::PortableBaselineStack& portableBaselineStack() {
+    return runtime()->portableBaselineStack();
+  }
+#endif
+
+ private:
+  // Base address of the native stack for the current thread.
+  mozilla::Maybe<JS::NativeStackBase> nativeStackBase_;
+
+ public:
+  JS::NativeStackBase nativeStackBase() const { return *nativeStackBase_; }
+
+ public:
+  /* If non-null, report JavaScript entry points to this monitor. */
+  js::ContextData<JS::dbg::AutoEntryMonitor*> entryMonitor;
+
+  /*
+   * Stack of debuggers that currently disallow debuggee execution.
+   *
+   * When we check for NX we are inside the debuggee compartment, and thus a
+   * stack of Debuggers that have prevented execution need to be tracked to
+   * enter the correct Debugger compartment to report the error.
+   */
+  js::ContextData<js::EnterDebuggeeNoExecute*> noExecuteDebuggerTop;
+
+#ifdef DEBUG
+  js::ContextData<uint32_t> inUnsafeCallWithABI;
+  js::ContextData<bool> hasAutoUnsafeCallWithABI;
+#endif
+
+#ifdef JS_SIMULATOR
+ private:
+  js::ContextData<js::jit::Simulator*> simulator_;
+
+ public:
+  js::jit::Simulator* simulator() const;
+  JS::NativeStackLimit* addressOfSimulatorStackLimit();
+#endif
+
+ public:
+  // State used by util/DoubleToString.cpp.
+  js::ContextData<DtoaState*> dtoaState;
+
+  /*
+   * When this flag is non-zero, any attempt to GC will be skipped. See the
+   * AutoSuppressGC class for for details.
+   */
+  js::ContextData<int32_t> suppressGC;
+
+#ifdef FUZZING_JS_FUZZILLI
+  uint32_t executionHash;
+  uint32_t executionHashInputs;
+#endif
+
+#ifdef DEBUG
+  js::ContextData<size_t> noNurseryAllocationCheck;
+
+  /*
+   * If this is 0, all cross-compartment proxies must be registered in the
+   * wrapper map. This checking must be disabled temporarily while creating
+   * new wrappers. When non-zero, this records the recursion depth of wrapper
+   * creation.
+   */
+  js::ContextData<uintptr_t> disableStrictProxyCheckingCount;
+
+  bool isNurseryAllocAllowed() { return noNurseryAllocationCheck == 0; }
+  void disallowNurseryAlloc() { ++noNurseryAllocationCheck; }
+  void allowNurseryAlloc() {
+    MOZ_ASSERT(!isNurseryAllocAllowed());
+    --noNurseryAllocationCheck;
+  }
+
+  bool isStrictProxyCheckingEnabled() {
+    return disableStrictProxyCheckingCount == 0;
+  }
+  void disableStrictProxyChecking() { ++disableStrictProxyCheckingCount; }
+  void enableStrictProxyChecking() {
+    MOZ_ASSERT(disableStrictProxyCheckingCount > 0);
+    --disableStrictProxyCheckingCount;
+  }
+#endif
+
+#if defined(DEBUG) || defined(JS_OOM_BREAKPOINT)
+  // We are currently running a simulated OOM test.
+  js::ContextData<bool> runningOOMTest;
+#endif
+
+  /*
+   * Some regions of code are hard for the static rooting hazard analysis to
+   * understand. In those cases, we trade the static analysis for a dynamic
+   * analysis. When this is non-zero, we should assert if we trigger, or
+   * might trigger, a GC.
+   */
+  js::ContextData<int> inUnsafeRegion;
+
+  // Count of AutoDisableGenerationalGC instances on the thread's stack.
+  js::ContextData<unsigned> generationalDisabled;
+
+  // Some code cannot tolerate compacting GC so it can be disabled temporarily
+  // with AutoDisableCompactingGC which uses this counter.
+  js::ContextData<unsigned> compactingDisabledCount;
+
+  // Match limit result for the most recent call to RegExpSearcher.
+  js::ContextData<uint32_t> regExpSearcherLastLimit;
+
+  static constexpr size_t offsetOfRegExpSearcherLastLimit() {
+    return offsetof(JSContext, regExpSearcherLastLimit);
+  }
+
+ private:
+  // Pools used for recycling name maps and vectors when parsing and
+  // emitting bytecode. Purged on GC when there are no active script
+  // compilations.
+  js::ContextData<js::frontend::NameCollectionPool> frontendCollectionPool_;
+
+ public:
+  js::frontend::NameCollectionPool& frontendCollectionPool() {
+    return frontendCollectionPool_.ref();
+  }
+
+  void verifyIsSafeToGC() {
+    MOZ_DIAGNOSTIC_ASSERT(!inUnsafeRegion,
+                          "[AutoAssertNoGC] possible GC in GC-unsafe region");
+  }
+
+  bool isInUnsafeRegion() const { return bool(inUnsafeRegion); }
+
+  // For JIT use.
+  MOZ_NEVER_INLINE void resetInUnsafeRegion() {
+    MOZ_ASSERT(inUnsafeRegion >= 0);
+    inUnsafeRegion = 0;
+  }
+
+  static constexpr size_t offsetOfInUnsafeRegion() {
+    return offsetof(JSContext, inUnsafeRegion);
+  }
+
+  /* Whether sampling should be enabled or not. */
+ private:
+  mozilla::Atomic<bool, mozilla::SequentiallyConsistent>
+      suppressProfilerSampling;
+
+ public:
+  bool isProfilerSamplingEnabled() const { return !suppressProfilerSampling; }
+  void disableProfilerSampling() { suppressProfilerSampling = true; }
+  void enableProfilerSampling() { suppressProfilerSampling = false; }
+
+ private:
+  js::wasm::Context wasm_;
+
+ public:
+  js::wasm::Context& wasm() { return wasm_; }
+
+  /* Temporary arena pool used while compiling and decompiling. */
+  static const size_t TEMP_LIFO_ALLOC_PRIMARY_CHUNK_SIZE = 4 * 1024;
+
+ private:
+  js::ContextData<js::LifoAlloc> tempLifoAlloc_;
+
+ public:
+  js::LifoAlloc& tempLifoAlloc() { return tempLifoAlloc_.ref(); }
+  const js::LifoAlloc& tempLifoAlloc() const { return tempLifoAlloc_.ref(); }
+
+  js::ContextData<uint32_t> debuggerMutations;
+
+  // Cache for jit::GetPcScript().
+  js::ContextData<js::UniquePtr<js::jit::PcScriptCache>> ionPcScriptCache;
+
+ private:
+  // Indicates if an exception is pending and the reason for it.
+  js::ContextData<JS::ExceptionStatus> status;
+  js::ContextData<JS::PersistentRooted<JS::Value>>
+      unwrappedException_; /* most-recently-thrown exception */
+  js::ContextData<JS::PersistentRooted<js::SavedFrame*>>
+      unwrappedExceptionStack_; /* stack when the exception was thrown */
+
+  JS::Value& unwrappedException() {
+    if (!unwrappedException_.ref().initialized()) {
+      unwrappedException_.ref().init(this);
+    }
+    return unwrappedException_.ref().get();
+  }
+
+  js::SavedFrame*& unwrappedExceptionStack() {
+    if (!unwrappedExceptionStack_.ref().initialized()) {
+      unwrappedExceptionStack_.ref().init(this);
+    }
+    return unwrappedExceptionStack_.ref().get();
+  }
+
+#ifdef DEBUG
+  // True if this context has ever thrown an exception because of an exceeded
+  // limit: stack space (ReportOverRecursed), memory (ReportOutOfMemory), or
+  // some other self-imposed limit (eg ReportOversizedAllocation). Used when
+  // detecting bailout loops in WarpOracle: bailout loops involving resource
+  // exhaustion are generally not interesting.
+  js::ContextData<bool> hadResourceExhaustion_;
+
+ public:
+  bool hadResourceExhaustion() const {
+    return hadResourceExhaustion_ || js::oom::simulator.isThreadSimulatingAny();
+  }
+#endif
+
+ public:
+  void reportResourceExhaustion() {
+#ifdef DEBUG
+    hadResourceExhaustion_ = true;
+#endif
+  }
+
+  js::ContextData<int32_t> reportGranularity; /* see vm/Probes.h */
+
+  js::ContextData<js::AutoResolving*> resolvingList;
+
+#ifdef DEBUG
+  js::ContextData<js::AutoEnterPolicy*> enteredPolicy;
+#endif
+
+  /* True if generating an error, to prevent runaway recursion. */
+  js::ContextData<bool> generatingError;
+
+ private:
+  /* State for object and array toSource conversion. */
+  js::ContextData<js::AutoCycleDetector::Vector> cycleDetectorVector_;
+
+ public:
+  js::AutoCycleDetector::Vector& cycleDetectorVector() {
+    return cycleDetectorVector_.ref();
+  }
+  const js::AutoCycleDetector::Vector& cycleDetectorVector() const {
+    return cycleDetectorVector_.ref();
+  }
+
+  /* Client opaque pointer. */
+  js::UnprotectedData<void*> data;
+
+  void initJitStackLimit();
+  void resetJitStackLimit();
+
+ public:
+  JS::ContextOptions& options() { return options_.ref(); }
+
+  bool runtimeMatches(JSRuntime* rt) const { return runtime_ == rt; }
+
+ private:
+  /*
+   * Youngest frame of a saved stack that will be picked up as an async stack
+   * by any new Activation, and is nullptr when no async stack should be used.
+   *
+   * The JS::AutoSetAsyncStackForNewCalls class can be used to set this.
+   *
+   * New activations will reset this to nullptr on construction after getting
+   * the current value, and will restore the previous value on destruction.
+   */
+  js::ContextData<JS::PersistentRooted<js::SavedFrame*>>
+      asyncStackForNewActivations_;
+
+ public:
+  js::SavedFrame*& asyncStackForNewActivations() {
+    if (!asyncStackForNewActivations_.ref().initialized()) {
+      asyncStackForNewActivations_.ref().init(this);
+    }
+    return asyncStackForNewActivations_.ref().get();
+  }
+
+  /*
+   * Value of asyncCause to be attached to asyncStackForNewActivations.
+   */
+  js::ContextData<const char*> asyncCauseForNewActivations;
+
+  /*
+   * True if the async call was explicitly requested, e.g. via
+   * callFunctionWithAsyncStack.
+   */
+  js::ContextData<bool> asyncCallIsExplicit;
+
+  bool currentlyRunningInInterpreter() const {
+    return activation()->isInterpreter();
+  }
+  bool currentlyRunningInJit() const { return activation()->isJit(); }
+  js::InterpreterFrame* interpreterFrame() const {
+    return activation()->asInterpreter()->current();
+  }
+  js::InterpreterRegs& interpreterRegs() const {
+    return activation()->asInterpreter()->regs();
+  }
+
+  /*
+   * Get the topmost script and optional pc on the stack. By default, this
+   * function only returns a JSScript in the current realm, returning nullptr
+   * if the current script is in a different realm. This behavior can be
+   * overridden by passing AllowCrossRealm::Allow.
+   */
+  enum class AllowCrossRealm { DontAllow = false, Allow = true };
+  inline JSScript* currentScript(
+      jsbytecode** pc = nullptr,
+      AllowCrossRealm allowCrossRealm = AllowCrossRealm::DontAllow) const;
+
+  inline void minorGC(JS::GCReason reason);
+
+ public:
+  bool isExceptionPending() const {
+    return JS::IsCatchableExceptionStatus(status);
+  }
+
+  /**
+   * Return the pending exception and wrap it into the current compartment.
+   */
+  [[nodiscard]] bool getPendingException(JS::MutableHandleValue rval);
+
+  /**
+   * Return the pending exception stack and wrap it into the current
+   * compartment. Return |JS::NullValue| when the pending exception has no stack
+   * attached.
+   */
+  [[nodiscard]] bool getPendingExceptionStack(JS::MutableHandleValue rval);
+
+  /**
+   * Return the pending exception stack, but does not wrap it into the current
+   * compartment. Return |nullptr| when the pending exception has no stack
+   * attached.
+   */
+  js::SavedFrame* getPendingExceptionStack();
+
+  bool isThrowingDebuggeeWouldRun();
+  bool isClosingGenerator();
+
+  void setPendingException(JS::HandleValue v,
+                           JS::Handle<js::SavedFrame*> stack);
+  void setPendingException(JS::HandleValue v,
+                           js::ShouldCaptureStack captureStack);
+
+  void clearPendingException() {
+    status = JS::ExceptionStatus::None;
+    unwrappedException().setUndefined();
+    unwrappedExceptionStack() = nullptr;
+  }
+
+  bool isThrowingOutOfMemory() const {
+    return status == JS::ExceptionStatus::OutOfMemory;
+  }
+  bool isThrowingOverRecursed() const {
+    return status == JS::ExceptionStatus::OverRecursed;
+  }
+  bool isPropagatingForcedReturn() const {
+    return status == JS::ExceptionStatus::ForcedReturn;
+  }
+  void setPropagatingForcedReturn() {
+    MOZ_ASSERT(status == JS::ExceptionStatus::None);
+    status = JS::ExceptionStatus::ForcedReturn;
+  }
+  void clearPropagatingForcedReturn() {
+    MOZ_ASSERT(status == JS::ExceptionStatus::ForcedReturn);
+    status = JS::ExceptionStatus::None;
+  }
+
+  /*
+   * See JS_SetTrustedPrincipals in jsapi.h.
+   * Note: !cx->realm() is treated as trusted.
+   */
+  inline bool runningWithTrustedPrincipals();
+
+  // Checks if the page's Content-Security-Policy (CSP) allows
+  // runtime code generation "unsafe-eval", or "wasm-unsafe-eval" for Wasm.
+  bool isRuntimeCodeGenEnabled(JS::RuntimeCode kind, js::HandleString code);
+
+  size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
+  size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const;
+
+  void trace(JSTracer* trc);
+
+  inline js::RuntimeCaches& caches();
+
+ public:
+  using InterruptCallbackVector =
+      js::Vector<JSInterruptCallback, 2, js::SystemAllocPolicy>;
+
+ private:
+  js::ContextData<InterruptCallbackVector> interruptCallbacks_;
+
+ public:
+  InterruptCallbackVector& interruptCallbacks() {
+    return interruptCallbacks_.ref();
+  }
+
+  js::ContextData<bool> interruptCallbackDisabled;
+
+  // Bitfield storing InterruptReason values.
+  mozilla::Atomic<uint32_t, mozilla::Relaxed> interruptBits_;
+
+  // Any thread can call requestInterrupt() to request that this thread
+  // stop running. To stop this thread, requestInterrupt sets two fields:
+  // interruptBits_ (a bitset of InterruptReasons) and jitStackLimit (set to
+  // JS::NativeStackLimitMin). The JS engine must continually poll one of these
+  // fields and call handleInterrupt if either field has the interrupt value.
+  //
+  // The point of setting jitStackLimit to JS::NativeStackLimitMin is that JIT
+  // code already needs to guard on jitStackLimit in every function prologue to
+  // avoid stack overflow, so we avoid a second branch on interruptBits_ by
+  // setting jitStackLimit to a value that is guaranteed to fail the guard.)
+  //
+  // Note that the writes to interruptBits_ and jitStackLimit use a Relaxed
+  // Atomic so, while the writes are guaranteed to eventually be visible to
+  // this thread, it can happen in any order. handleInterrupt calls the
+  // interrupt callback if either is set, so it really doesn't matter as long
+  // as the JS engine is continually polling at least one field. In corner
+  // cases, this relaxed ordering could lead to an interrupt handler being
+  // called twice in succession after a single requestInterrupt call, but
+  // that's fine.
+  void requestInterrupt(js::InterruptReason reason);
+  bool handleInterrupt();
+
+  MOZ_ALWAYS_INLINE bool hasAnyPendingInterrupt() const {
+    static_assert(sizeof(interruptBits_) == sizeof(uint32_t),
+                  "Assumed by JIT callers");
+    return interruptBits_ != 0;
+  }
+  bool hasPendingInterrupt(js::InterruptReason reason) const {
+    return interruptBits_ & uint32_t(reason);
+  }
+  void clearPendingInterrupt(js::InterruptReason reason);
+
+  // For JIT use. Points to the inlined ICScript for a baseline script
+  // being invoked as part of a trial inlining.  Contains nullptr at
+  // all times except for the brief moment between being set in the
+  // caller and read in the callee's prologue.
+  js::ContextData<js::jit::ICScript*> inlinedICScript_;
+
+ public:
+  void* addressOfInterruptBits() { return &interruptBits_; }
+  void* addressOfJitStackLimit() { return &jitStackLimit; }
+  void* addressOfJitStackLimitNoInterrupt() {
+    return &jitStackLimitNoInterrupt;
+  }
+  void* addressOfZone() { return &zone_; }
+
+  const void* addressOfRealm() const { return &realm_; }
+
+  void* addressOfInlinedICScript() { return &inlinedICScript_; }
+
+  // Futex state, used by Atomics.wait() and Atomics.wake() on the Atomics
+  // object.
+  js::FutexThread fx;
+
+  mozilla::Atomic<JS::NativeStackLimit, mozilla::Relaxed> jitStackLimit;
+
+  // Like jitStackLimit, but not reset to trigger interrupts.
+  js::ContextData<JS::NativeStackLimit> jitStackLimitNoInterrupt;
+
+  // Queue of pending jobs as described in ES2016 section 8.4.
+  //
+  // This is a non-owning pointer to either:
+  // - a JobQueue implementation the embedding provided by calling
+  //   JS::SetJobQueue, owned by the embedding, or
+  // - our internal JobQueue implementation, established by calling
+  //   js::UseInternalJobQueues, owned by JSContext::internalJobQueue below.
+  js::ContextData<JS::JobQueue*> jobQueue;
+
+  // If the embedding has called js::UseInternalJobQueues, this is the owning
+  // pointer to our internal JobQueue implementation, which JSContext::jobQueue
+  // borrows.
+  js::ContextData<js::UniquePtr<js::InternalJobQueue>> internalJobQueue;
+
+  // True if jobQueue is empty, or we are running the last job in the queue.
+  // Such conditions permit optimizations around `await` expressions.
+  js::ContextData<bool> canSkipEnqueuingJobs;
+
+  js::ContextData<JS::PromiseRejectionTrackerCallback>
+      promiseRejectionTrackerCallback;
+  js::ContextData<void*> promiseRejectionTrackerCallbackData;
+
+  JSObject* getIncumbentGlobal(JSContext* cx);
+  bool enqueuePromiseJob(JSContext* cx, js::HandleFunction job,
+                         js::HandleObject promise,
+                         js::HandleObject incumbentGlobal);
+  void addUnhandledRejectedPromise(JSContext* cx, js::HandleObject promise);
+  void removeUnhandledRejectedPromise(JSContext* cx, js::HandleObject promise);
+
+ private:
+  template <class... Args>
+  inline void checkImpl(const Args&... args);
+
+  bool contextChecksEnabled() const {
+    // Don't perform these checks when called from a finalizer. The checking
+    // depends on other objects not having been swept yet.
+    return !RuntimeHeapIsCollecting(runtime()->heapState());
+  }
+
+ public:
+  // Assert the arguments are in this context's realm (for scripts),
+  // compartment (for objects) or zone (for strings, symbols).
+  template <class... Args>
+  inline void check(const Args&... args);
+  template <class... Args>
+  inline void releaseCheck(const Args&... args);
+  template <class... Args>
+  MOZ_ALWAYS_INLINE void debugOnlyCheck(const Args&... args);
+
+#ifdef JS_STRUCTURED_SPEW
+ private:
+  // Spewer for this thread
+  js::UnprotectedData<js::StructuredSpewer> structuredSpewer_;
+
+ public:
+  js::StructuredSpewer& spewer() { return structuredSpewer_.ref(); }
+#endif
+
+  // Debugger having set `exclusiveDebuggerOnEval` property to true
+  // want their evaluations and calls to be ignore by all other Debuggers
+  // except themself. This flag indicates whether we are in such debugger
+  // evaluation, and which debugger initiated the evaluation. This debugger
+  // has other references on the stack and does not need to be traced.
+  js::ContextData<js::Debugger*> insideExclusiveDebuggerOnEval;
+
+}; /* struct JSContext */
+
+inline JSContext* JSRuntime::mainContextFromOwnThread() {
+  MOZ_ASSERT(mainContextFromAnyThread() == js::TlsContext.get());
+  return mainContextFromAnyThread();
+}
+
+namespace js {
+
+struct MOZ_RAII AutoResolving {
+ public:
+  enum Kind { LOOKUP, WATCH };
+
+  AutoResolving(JSContext* cx, HandleObject obj, HandleId id,
+                Kind kind = LOOKUP)
+      : context(cx), object(obj), id(id), kind(kind), link(cx->resolvingList) {
+    MOZ_ASSERT(obj);
+    cx->resolvingList = this;
+  }
+
+  ~AutoResolving() {
+    MOZ_ASSERT(context->resolvingList == this);
+    context->resolvingList = link;
+  }
+
+  bool alreadyStarted() const { return link && alreadyStartedSlow(); }
+
+ private:
+  bool alreadyStartedSlow() const;
+
+  JSContext* const context;
+  HandleObject object;
+  HandleId id;
+  Kind const kind;
+  AutoResolving* const link;
+};
+
+/*
+ * Create and destroy functions for JSContext, which is manually allocated
+ * and exclusively owned.
+ */
+extern JSContext* NewContext(uint32_t maxBytes, JSRuntime* parentRuntime);
+
+extern void DestroyContext(JSContext* cx);
+
+/* |callee| requires a usage string provided by JS_DefineFunctionsWithHelp. */
+extern void ReportUsageErrorASCII(JSContext* cx, HandleObject callee,
+                                  const char* msg);
+
+extern void ReportIsNotDefined(JSContext* cx, Handle<PropertyName*> name);
+
+extern void ReportIsNotDefined(JSContext* cx, HandleId id);
+
+/*
+ * Report an attempt to access the property of a null or undefined value (v).
+ */
+extern void ReportIsNullOrUndefinedForPropertyAccess(JSContext* cx,
+                                                     HandleValue v, int vIndex);
+extern void ReportIsNullOrUndefinedForPropertyAccess(JSContext* cx,
+                                                     HandleValue v, int vIndex,
+                                                     HandleId key);
+
+/*
+ * Report error using js::DecompileValueGenerator(cx, spindex, v, fallback) as
+ * the first argument for the error message.
+ */
+extern bool ReportValueError(JSContext* cx, const unsigned errorNumber,
+                             int spindex, HandleValue v, HandleString fallback,
+                             const char* arg1 = nullptr,
+                             const char* arg2 = nullptr);
+
+JSObject* CreateErrorNotesArray(JSContext* cx, JSErrorReport* report);
+
+/************************************************************************/
+
+/*
+ * Encapsulates an external array of values and adds a trace method, for use in
+ * Rooted.
+ */
+class MOZ_STACK_CLASS ExternalValueArray {
+ public:
+  ExternalValueArray(size_t len, Value* vec) : array_(vec), length_(len) {}
+
+  Value* begin() { return array_; }
+  size_t length() { return length_; }
+
+  void trace(JSTracer* trc);
+
+ private:
+  Value* array_;
+  size_t length_;
+};
+
+/* RootedExternalValueArray roots an external array of Values. */
+class MOZ_RAII RootedExternalValueArray
+    : public JS::Rooted<ExternalValueArray> {
+ public:
+  RootedExternalValueArray(JSContext* cx, size_t len, Value* vec)
+      : JS::Rooted<ExternalValueArray>(cx, ExternalValueArray(len, vec)) {}
+
+ private:
+};
+
+class AutoAssertNoPendingException {
+#ifdef DEBUG
+  JSContext* cx_;
+
+ public:
+  explicit AutoAssertNoPendingException(JSContext* cxArg) : cx_(cxArg) {
+    MOZ_ASSERT(!JS_IsExceptionPending(cx_));
+  }
+
+  ~AutoAssertNoPendingException() { MOZ_ASSERT(!JS_IsExceptionPending(cx_)); }
+#else
+ public:
+  explicit AutoAssertNoPendingException(JSContext* cxArg) {}
+#endif
+};
+
+class MOZ_RAII AutoNoteExclusiveDebuggerOnEval {
+  JSContext* cx;
+  Debugger* oldValue;
+
+ public:
+  AutoNoteExclusiveDebuggerOnEval(JSContext* cx, Debugger* dbg)
+      : cx(cx), oldValue(cx->insideExclusiveDebuggerOnEval) {
+    cx->insideExclusiveDebuggerOnEval = dbg;
+  }
+
+  ~AutoNoteExclusiveDebuggerOnEval() {
+    cx->insideExclusiveDebuggerOnEval = oldValue;
+  }
+};
+
+enum UnsafeABIStrictness {
+  NoExceptions,
+  AllowPendingExceptions,
+  AllowThrownExceptions
+};
+
+// Should be used in functions called directly from JIT code (with
+// masm.callWithABI) to assert invariants in debug builds.
+// In debug mode, masm.callWithABI inserts code to verify that the
+// callee function uses AutoUnsafeCallWithABI.
+// While this object is live:
+// 1. cx->hasAutoUnsafeCallWithABI must be true.
+// 2. We can't GC.
+// 3. Exceptions should not be pending/thrown.
+//
+// Note that #3 is a precaution, not a requirement. By default, we
+// assert that the function is not called with a pending exception,
+// and that it does not throw an exception itself.
+class MOZ_RAII AutoUnsafeCallWithABI {
+#ifdef DEBUG
+  JSContext* cx_;
+  bool nested_;
+  bool checkForPendingException_;
+#endif
+  JS::AutoCheckCannotGC nogc;
+
+ public:
+#ifdef DEBUG
+  explicit AutoUnsafeCallWithABI(
+      UnsafeABIStrictness strictness = UnsafeABIStrictness::NoExceptions);
+  ~AutoUnsafeCallWithABI();
+#else
+  explicit AutoUnsafeCallWithABI(
+      UnsafeABIStrictness unused_ = UnsafeABIStrictness::NoExceptions) {}
+#endif
+};
+
+} /* namespace js */
+
+#define CHECK_THREAD(cx) \
+  MOZ_ASSERT_IF(cx, js::CurrentThreadCanAccessRuntime(cx->runtime()))
+
+/**
+ * [SMDOC] JS::Result transitional macros
+ *
+ * ## Checking Results when your return type is not Result
+ *
+ * This header defines alternatives to MOZ_TRY and MOZ_TRY_VAR for when you
+ * need to call a `Result` function from a function that uses false or nullptr
+ * to indicate errors:
+ *
+ *     JS_TRY_OR_RETURN_FALSE(cx, DefenestrateObject(cx, obj));
+ *     JS_TRY_VAR_OR_RETURN_FALSE(cx, v, GetObjectThrug(cx, obj));
+ *
+ *     JS_TRY_VAR_OR_RETURN_NULL(cx, v, GetObjectThrug(cx, obj));
+ *
+ * When TRY is not what you want, because you need to do some cleanup or
+ * recovery on error, use this idiom:
+ *
+ *     if (!cx->resultToBool(expr_that_is_a_Result)) {
+ *         ... your recovery code here ...
+ *     }
+ *
+ * In place of a tail call, you can use one of these methods:
+ *
+ *     return cx->resultToBool(expr);  // false on error
+ *     return cx->resultToPtr(expr);  // null on error
+ *
+ * Once we are using `Result` everywhere, including in public APIs, all of
+ * these will go away.
+ */
+
+/**
+ * JS_TRY_OR_RETURN_FALSE(cx, expr) runs expr to compute a Result value.
+ * On success, nothing happens; on error, it returns false immediately.
+ *
+ * Implementation note: this involves cx because this may eventually
+ * do the work of setting a pending exception or reporting OOM.
+ */
+#define JS_TRY_OR_RETURN_FALSE(cx, expr)                           \
+  do {                                                             \
+    auto tmpResult_ = (expr);                                      \
+    if (tmpResult_.isErr()) return (cx)->resultToBool(tmpResult_); \
+  } while (0)
+
+#define JS_TRY_VAR_OR_RETURN_FALSE(cx, target, expr)               \
+  do {                                                             \
+    auto tmpResult_ = (expr);                                      \
+    if (tmpResult_.isErr()) return (cx)->resultToBool(tmpResult_); \
+    (target) = tmpResult_.unwrap();                                \
+  } while (0)
+
+#define JS_TRY_VAR_OR_RETURN_NULL(cx, target, expr)     \
+  do {                                                  \
+    auto tmpResult_ = (expr);                           \
+    if (tmpResult_.isErr()) {                           \
+      MOZ_ALWAYS_FALSE((cx)->resultToBool(tmpResult_)); \
+      return nullptr;                                   \
+    }                                                   \
+    (target) = tmpResult_.unwrap();                     \
+  } while (0)
+
+#endif /* vm_JSContext_h */