Add m-esr52 at 52.6.0

1 files changed, 1777 insertions, 0 deletions

diff --git a/js/src/vm/Runtime.h b/js/src/vm/Runtime.h
new file mode 100644
index 000000000..4f7755b9d
--- /dev/null
+++ b/js/src/vm/Runtime.h
@@ -0,0 +1,1777 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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/. */
+
+#ifndef vm_Runtime_h
+#define vm_Runtime_h
+
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/LinkedList.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/PodOperations.h"
+#include "mozilla/Scoped.h"
+#include "mozilla/ThreadLocal.h"
+#include "mozilla/Vector.h"
+
+#include <setjmp.h>
+
+#include "jsatom.h"
+#include "jsclist.h"
+#include "jsscript.h"
+
+#ifdef XP_DARWIN
+# include "wasm/WasmSignalHandlers.h"
+#endif
+#include "builtin/AtomicsObject.h"
+#include "builtin/Intl.h"
+#include "builtin/Promise.h"
+#include "ds/FixedSizeHash.h"
+#include "frontend/NameCollections.h"
+#include "gc/GCRuntime.h"
+#include "gc/Tracer.h"
+#include "irregexp/RegExpStack.h"
+#include "js/Debug.h"
+#include "js/GCVector.h"
+#include "js/HashTable.h"
+#ifdef DEBUG
+# include "js/Proxy.h" // For AutoEnterPolicy
+#endif
+#include "js/UniquePtr.h"
+#include "js/Vector.h"
+#include "threading/Thread.h"
+#include "vm/CodeCoverage.h"
+#include "vm/CommonPropertyNames.h"
+#include "vm/DateTime.h"
+#include "vm/MallocProvider.h"
+#include "vm/Scope.h"
+#include "vm/SharedImmutableStringsCache.h"
+#include "vm/SPSProfiler.h"
+#include "vm/Stack.h"
+#include "vm/Stopwatch.h"
+#include "vm/Symbol.h"
+
+#ifdef _MSC_VER
+#pragma warning(push)
+#pragma warning(disable:4100) /* Silence unreferenced formal parameter warnings */
+#endif
+
+namespace js {
+
+class PerThreadData;
+class ExclusiveContext;
+class AutoKeepAtoms;
+class EnterDebuggeeNoExecute;
+#ifdef JS_TRACE_LOGGING
+class TraceLoggerThread;
+#endif
+
+typedef Vector<UniquePtr<PromiseTask>, 0, SystemAllocPolicy> PromiseTaskPtrVector;
+
+/* Thread Local Storage slot for storing the runtime for a thread. */
+extern MOZ_THREAD_LOCAL(PerThreadData*) TlsPerThreadData;
+
+} // namespace js
+
+struct DtoaState;
+
+#ifdef JS_SIMULATOR_ARM64
+namespace vixl {
+class Simulator;
+}
+#endif
+
+namespace js {
+
+extern MOZ_COLD void
+ReportOutOfMemory(ExclusiveContext* cx);
+
+extern MOZ_COLD void
+ReportAllocationOverflow(ExclusiveContext* maybecx);
+
+extern MOZ_COLD void
+ReportOverRecursed(ExclusiveContext* cx);
+
+class Activation;
+class ActivationIterator;
+class WasmActivation;
+
+namespace jit {
+class JitRuntime;
+class JitActivation;
+struct PcScriptCache;
+struct AutoFlushICache;
+class CompileRuntime;
+
+#ifdef JS_SIMULATOR_ARM64
+typedef vixl::Simulator Simulator;
+#elif defined(JS_SIMULATOR)
+class Simulator;
+#endif
+} // namespace jit
+
+/*
+ * A FreeOp can do one thing: free memory. For convenience, it has delete_
+ * convenience methods that also call destructors.
+ *
+ * FreeOp is passed to finalizers and other sweep-phase hooks so that we do not
+ * need to pass a JSContext to those hooks.
+ */
+class FreeOp : public JSFreeOp
+{
+    Vector<void*, 0, SystemAllocPolicy> freeLaterList;
+    jit::JitPoisonRangeVector jitPoisonRanges;
+
+  public:
+    static FreeOp* get(JSFreeOp* fop) {
+        return static_cast<FreeOp*>(fop);
+    }
+
+    explicit FreeOp(JSRuntime* maybeRuntime);
+    ~FreeOp();
+
+    bool onMainThread() const {
+        return runtime_ != nullptr;
+    }
+
+    bool maybeOffMainThread() const {
+        // Sometimes background finalization happens on the main thread so
+        // runtime_ being null doesn't always mean we are off the main thread.
+        return !runtime_;
+    }
+
+    bool isDefaultFreeOp() const;
+
+    inline void free_(void* p);
+    inline void freeLater(void* p);
+
+    inline bool appendJitPoisonRange(const jit::JitPoisonRange& range);
+
+    template <class T>
+    inline void delete_(T* p) {
+        if (p) {
+            p->~T();
+            free_(p);
+        }
+    }
+};
+
+} /* namespace js */
+
+namespace JS {
+struct RuntimeSizes;
+} // namespace JS
+
+/* Various built-in or commonly-used names pinned on first context. */
+struct JSAtomState
+{
+#define PROPERTYNAME_FIELD(idpart, id, text) js::ImmutablePropertyNamePtr id;
+    FOR_EACH_COMMON_PROPERTYNAME(PROPERTYNAME_FIELD)
+#undef PROPERTYNAME_FIELD
+#define PROPERTYNAME_FIELD(name, code, init, clasp) js::ImmutablePropertyNamePtr name;
+    JS_FOR_EACH_PROTOTYPE(PROPERTYNAME_FIELD)
+#undef PROPERTYNAME_FIELD
+#define PROPERTYNAME_FIELD(name) js::ImmutablePropertyNamePtr name;
+    JS_FOR_EACH_WELL_KNOWN_SYMBOL(PROPERTYNAME_FIELD)
+#undef PROPERTYNAME_FIELD
+#define PROPERTYNAME_FIELD(name) js::ImmutablePropertyNamePtr Symbol_##name;
+    JS_FOR_EACH_WELL_KNOWN_SYMBOL(PROPERTYNAME_FIELD)
+#undef PROPERTYNAME_FIELD
+
+    js::ImmutablePropertyNamePtr* wellKnownSymbolNames() {
+#define FIRST_PROPERTYNAME_FIELD(name) return &name;
+    JS_FOR_EACH_WELL_KNOWN_SYMBOL(FIRST_PROPERTYNAME_FIELD)
+#undef FIRST_PROPERTYNAME_FIELD
+    }
+
+    js::ImmutablePropertyNamePtr* wellKnownSymbolDescriptions() {
+#define FIRST_PROPERTYNAME_FIELD(name) return &Symbol_ ##name;
+    JS_FOR_EACH_WELL_KNOWN_SYMBOL(FIRST_PROPERTYNAME_FIELD)
+#undef FIRST_PROPERTYNAME_FIELD
+    }
+};
+
+namespace js {
+
+/*
+ * Storage for well-known symbols. It's a separate struct from the Runtime so
+ * that it can be shared across multiple runtimes. As in JSAtomState, each
+ * field is a smart pointer that's immutable once initialized.
+ * `rt->wellKnownSymbols->iterator` is convertible to Handle<Symbol*>.
+ *
+ * Well-known symbols are never GC'd. The description() of each well-known
+ * symbol is a permanent atom.
+ */
+struct WellKnownSymbols
+{
+#define DECLARE_SYMBOL(name) js::ImmutableSymbolPtr name;
+    JS_FOR_EACH_WELL_KNOWN_SYMBOL(DECLARE_SYMBOL)
+#undef DECLARE_SYMBOL
+
+    const ImmutableSymbolPtr& get(size_t u) const {
+        MOZ_ASSERT(u < JS::WellKnownSymbolLimit);
+        const ImmutableSymbolPtr* symbols = reinterpret_cast<const ImmutableSymbolPtr*>(this);
+        return symbols[u];
+    }
+
+    const ImmutableSymbolPtr& get(JS::SymbolCode code) const {
+        return get(size_t(code));
+    }
+
+    WellKnownSymbols() {}
+    WellKnownSymbols(const WellKnownSymbols&) = delete;
+    WellKnownSymbols& operator=(const WellKnownSymbols&) = delete;
+};
+
+#define NAME_OFFSET(name)       offsetof(JSAtomState, name)
+
+inline HandlePropertyName
+AtomStateOffsetToName(const JSAtomState& atomState, size_t offset)
+{
+    return *reinterpret_cast<js::ImmutablePropertyNamePtr*>((char*)&atomState + offset);
+}
+
+// There are several coarse locks in the enum below. These may be either
+// per-runtime or per-process. When acquiring more than one of these locks,
+// the acquisition must be done in the order below to avoid deadlocks.
+enum RuntimeLock {
+    ExclusiveAccessLock,
+    HelperThreadStateLock,
+    GCLock
+};
+
+inline bool
+CanUseExtraThreads()
+{
+    extern bool gCanUseExtraThreads;
+    return gCanUseExtraThreads;
+}
+
+void DisableExtraThreads();
+
+/*
+ * Encapsulates portions of the runtime/context that are tied to a
+ * single active thread.  Instances of this structure can occur for
+ * the main thread as |JSRuntime::mainThread|, for select operations
+ * performed off thread, such as parsing.
+ */
+class PerThreadData
+{
+    /*
+     * Backpointer to the full shared JSRuntime* with which this
+     * thread is associated.  This is private because accessing the
+     * fields of this runtime can provoke race conditions, so the
+     * intention is that access will be mediated through safe
+     * functions like |runtimeFromMainThread| and |associatedWith()| below.
+     */
+    JSRuntime* runtime_;
+
+  public:
+#ifdef JS_TRACE_LOGGING
+    TraceLoggerMainThread*  traceLogger;
+#endif
+
+    /* Pointer to the current AutoFlushICache. */
+    js::jit::AutoFlushICache* autoFlushICache_;
+
+  public:
+    /* State used by jsdtoa.cpp. */
+    DtoaState*          dtoaState;
+
+    /*
+     * When this flag is non-zero, any attempt to GC will be skipped. It is used
+     * to suppress GC when reporting an OOM (see ReportOutOfMemory) and in
+     * debugging facilities that cannot tolerate a GC and would rather OOM
+     * immediately, such as utilities exposed to GDB. Setting this flag is
+     * extremely dangerous and should only be used when in an OOM situation or
+     * in non-exposed debugging facilities.
+     */
+    int32_t suppressGC;
+
+#ifdef DEBUG
+    // Whether this thread is actively Ion compiling.
+    bool ionCompiling;
+
+    // Whether this thread is actively Ion compiling in a context where a minor
+    // GC could happen simultaneously. If this is true, this thread cannot use
+    // any pointers into the nursery.
+    bool ionCompilingSafeForMinorGC;
+
+    // Whether this thread is currently performing GC.  This thread could be the
+    // main thread or a helper thread while the main thread is running the
+    // collector.
+    bool performingGC;
+
+    // Whether this thread is currently sweeping GC things.  This thread could
+    // be the main thread or a helper thread while the main thread is running
+    // the mutator.  This is used to assert that destruction of GCPtr only
+    // happens when we are sweeping.
+    bool gcSweeping;
+#endif
+
+    // Pools used for recycling name maps and vectors when parsing and
+    // emitting bytecode. Purged on GC when there are no active script
+    // compilations.
+    frontend::NameCollectionPool frontendCollectionPool;
+
+    explicit PerThreadData(JSRuntime* runtime);
+    ~PerThreadData();
+
+    bool init();
+
+    bool associatedWith(const JSRuntime* rt) { return runtime_ == rt; }
+    inline JSRuntime* runtimeFromMainThread();
+    inline JSRuntime* runtimeIfOnOwnerThread();
+
+    JSContext* contextFromMainThread();
+
+    inline bool exclusiveThreadsPresent();
+
+    // For threads which may be associated with different runtimes, depending
+    // on the work they are doing.
+    class MOZ_STACK_CLASS AutoEnterRuntime
+    {
+        PerThreadData* pt;
+
+      public:
+        AutoEnterRuntime(PerThreadData* pt, JSRuntime* rt)
+          : pt(pt)
+        {
+            MOZ_ASSERT(!pt->runtime_);
+            pt->runtime_ = rt;
+        }
+
+        ~AutoEnterRuntime() {
+            pt->runtime_ = nullptr;
+        }
+    };
+
+    js::jit::AutoFlushICache* autoFlushICache() const;
+    void setAutoFlushICache(js::jit::AutoFlushICache* afc);
+
+#ifdef JS_SIMULATOR
+    js::jit::Simulator* simulator() const;
+#endif
+};
+
+using ScriptAndCountsVector = GCVector<ScriptAndCounts, 0, SystemAllocPolicy>;
+
+class AutoLockForExclusiveAccess;
+} // namespace js
+
+struct JSRuntime : public JS::shadow::Runtime,
+                   public js::MallocProvider<JSRuntime>
+{
+    /*
+     * Per-thread data for the main thread that is associated with
+     * this JSRuntime, as opposed to any worker threads used in
+     * parallel sections.  See definition of |PerThreadData| struct
+     * above for more details.
+     *
+     * NB: This field is statically asserted to be at offset
+     * sizeof(js::shadow::Runtime). See
+     * PerThreadDataFriendFields::getMainThread.
+     */
+    js::PerThreadData mainThread;
+
+    /*
+     * If Baseline or Ion code is on the stack, and has called into C++, this
+     * will be aligned to an exit frame.
+     */
+    uint8_t*            jitTop;
+
+     /*
+     * Points to the most recent JitActivation pushed on the thread.
+     * See JitActivation constructor in vm/Stack.cpp
+     */
+    js::jit::JitActivation* jitActivation;
+
+    /* See comment for JSRuntime::interrupt_. */
+  protected:
+    mozilla::Atomic<uintptr_t, mozilla::Relaxed> jitStackLimit_;
+
+    // Like jitStackLimit_, but not reset to trigger interrupts.
+    uintptr_t jitStackLimitNoInterrupt_;
+
+  public:
+    uintptr_t jitStackLimit() const { return jitStackLimit_; }
+
+    // For read-only JIT use:
+    void* addressOfJitStackLimit() { return &jitStackLimit_; }
+    static size_t offsetOfJitStackLimit() { return offsetof(JSRuntime, jitStackLimit_); }
+
+    void* addressOfJitStackLimitNoInterrupt() { return &jitStackLimitNoInterrupt_; }
+
+    // Information about the heap allocated backtrack stack used by RegExp JIT code.
+    js::irregexp::RegExpStack regexpStack;
+
+#ifdef DEBUG
+  private:
+    // The number of possible bailing places encounters before forcefully bailing
+    // in that place. Zero means inactive.
+    uint32_t ionBailAfter_;
+
+  public:
+    void* addressOfIonBailAfter() { return &ionBailAfter_; }
+
+    // Set after how many bailing places we should forcefully bail.
+    // Zero disables this feature.
+    void setIonBailAfter(uint32_t after) {
+        ionBailAfter_ = after;
+    }
+#endif
+
+  private:
+    friend class js::Activation;
+    friend class js::ActivationIterator;
+    friend class js::jit::JitActivation;
+    friend class js::WasmActivation;
+    friend class js::jit::CompileRuntime;
+
+  protected:
+    /*
+     * Points to the most recent activation running on the thread.
+     * See Activation comment in vm/Stack.h.
+     */
+    js::Activation* activation_;
+
+    /*
+     * Points to the most recent profiling activation running on the
+     * thread.
+     */
+    js::Activation * volatile profilingActivation_;
+
+    /*
+     * The profiler sampler generation after the latest sample.
+     *
+     * The lapCount indicates the number of largest number of 'laps'
+     * (wrapping from high to low) that occurred when writing entries
+     * into the sample buffer.  All JitcodeGlobalMap entries referenced
+     * from a given sample are assigned the generation of the sample buffer
+     * at the START of the run.  If multiple laps occur, then some entries
+     * (towards the end) will be written out with the "wrong" generation.
+     * The lapCount indicates the required fudge factor to use to compare
+     * entry generations with the sample buffer generation.
+     */
+    mozilla::Atomic<uint32_t, mozilla::ReleaseAcquire> profilerSampleBufferGen_;
+    mozilla::Atomic<uint32_t, mozilla::ReleaseAcquire> profilerSampleBufferLapCount_;
+
+    /* See WasmActivation comment. */
+    js::WasmActivation * volatile wasmActivationStack_;
+
+  public:
+    /* If non-null, report JavaScript entry points to this monitor. */
+    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::EnterDebuggeeNoExecute* noExecuteDebuggerTop;
+
+    js::Activation* const* addressOfActivation() const {
+        return &activation_;
+    }
+    static unsigned offsetOfActivation() {
+        return offsetof(JSRuntime, activation_);
+    }
+
+    js::Activation* profilingActivation() const {
+        return profilingActivation_;
+    }
+    void* addressOfProfilingActivation() {
+        return (void*) &profilingActivation_;
+    }
+    static unsigned offsetOfProfilingActivation() {
+        return offsetof(JSRuntime, profilingActivation_);
+    }
+
+    uint32_t profilerSampleBufferGen() {
+        return profilerSampleBufferGen_;
+    }
+    void resetProfilerSampleBufferGen() {
+        profilerSampleBufferGen_ = 0;
+    }
+    void setProfilerSampleBufferGen(uint32_t gen) {
+        // May be called from sampler thread or signal handler; use
+        // compareExchange to make sure we have monotonic increase.
+        for (;;) {
+            uint32_t curGen = profilerSampleBufferGen_;
+            if (curGen >= gen)
+                break;
+
+            if (profilerSampleBufferGen_.compareExchange(curGen, gen))
+                break;
+        }
+    }
+
+    uint32_t profilerSampleBufferLapCount() {
+        MOZ_ASSERT(profilerSampleBufferLapCount_ > 0);
+        return profilerSampleBufferLapCount_;
+    }
+    void resetProfilerSampleBufferLapCount() {
+        profilerSampleBufferLapCount_ = 1;
+    }
+    void updateProfilerSampleBufferLapCount(uint32_t lapCount) {
+        MOZ_ASSERT(profilerSampleBufferLapCount_ > 0);
+
+        // May be called from sampler thread or signal handler; use
+        // compareExchange to make sure we have monotonic increase.
+        for (;;) {
+            uint32_t curLapCount = profilerSampleBufferLapCount_;
+            if (curLapCount >= lapCount)
+                break;
+
+            if (profilerSampleBufferLapCount_.compareExchange(curLapCount, lapCount))
+                break;
+        }
+    }
+
+    js::WasmActivation* wasmActivationStack() const {
+        return wasmActivationStack_;
+    }
+    static js::WasmActivation* innermostWasmActivation() {
+        js::PerThreadData* ptd = js::TlsPerThreadData.get();
+        return ptd ? ptd->runtimeFromMainThread()->wasmActivationStack_ : nullptr;
+    }
+
+    js::Activation* activation() const {
+        return activation_;
+    }
+
+    /*
+     * If non-null, another runtime guaranteed to outlive this one and whose
+     * permanent data may be used by this one where possible.
+     */
+    JSRuntime* parentRuntime;
+
+  private:
+#ifdef DEBUG
+    /* The number of child runtimes that have this runtime as their parent. */
+    mozilla::Atomic<size_t> childRuntimeCount;
+
+    class AutoUpdateChildRuntimeCount
+    {
+        JSRuntime* parent_;
+
+      public:
+        explicit AutoUpdateChildRuntimeCount(JSRuntime* parent)
+          : parent_(parent)
+        {
+            if (parent_)
+                parent_->childRuntimeCount++;
+        }
+
+        ~AutoUpdateChildRuntimeCount() {
+            if (parent_)
+                parent_->childRuntimeCount--;
+        }
+    };
+
+    AutoUpdateChildRuntimeCount updateChildRuntimeCount;
+#endif
+
+    mozilla::Atomic<uint32_t, mozilla::Relaxed> interrupt_;
+
+    /* Call this to accumulate telemetry data. */
+    JSAccumulateTelemetryDataCallback telemetryCallback;
+  public:
+    // Accumulates data for Firefox telemetry. |id| is the ID of a JS_TELEMETRY_*
+    // histogram. |key| provides an additional key to identify the histogram.
+    // |sample| is the data to add to the histogram.
+    void addTelemetry(int id, uint32_t sample, const char* key = nullptr);
+
+    void setTelemetryCallback(JSRuntime* rt, JSAccumulateTelemetryDataCallback callback);
+
+    enum InterruptMode {
+        RequestInterruptUrgent,
+        RequestInterruptCanWait
+    };
+
+    // Any thread can call requestInterrupt() to request that the main JS thread
+    // stop running and call the interrupt callback (allowing the interrupt
+    // callback to halt execution). To stop the main JS thread, requestInterrupt
+    // sets two fields: interrupt_ (set to true) and jitStackLimit_ (set to
+    // UINTPTR_MAX). 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 UINTPTR_MAX 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 interrupt_ by setting
+    // jitStackLimit_ to a value that is guaranteed to fail the guard.)
+    //
+    // Note that the writes to interrupt_ and jitStackLimit_ use a Relaxed
+    // Atomic so, while the writes are guaranteed to eventually be visible to
+    // the main 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(InterruptMode mode);
+    bool handleInterrupt(JSContext* cx);
+
+    MOZ_ALWAYS_INLINE bool hasPendingInterrupt() const {
+        return interrupt_;
+    }
+
+    // For read-only JIT use:
+    void* addressOfInterruptUint32() {
+        static_assert(sizeof(interrupt_) == sizeof(uint32_t), "Assumed by JIT callers");
+        return &interrupt_;
+    }
+
+    // Set when handling a segfault in the wasm signal handler.
+    bool handlingSegFault;
+
+  private:
+    // Set when we're handling an interrupt of JIT/wasm code in
+    // InterruptRunningJitCode.
+    mozilla::Atomic<bool> handlingJitInterrupt_;
+
+  public:
+    bool startHandlingJitInterrupt() {
+        // Return true if we changed handlingJitInterrupt_ from
+        // false to true.
+        return handlingJitInterrupt_.compareExchange(false, true);
+    }
+    void finishHandlingJitInterrupt() {
+        MOZ_ASSERT(handlingJitInterrupt_);
+        handlingJitInterrupt_ = false;
+    }
+    bool handlingJitInterrupt() const {
+        return handlingJitInterrupt_;
+    }
+
+    using InterruptCallbackVector = js::Vector<JSInterruptCallback, 2, js::SystemAllocPolicy>;
+    InterruptCallbackVector interruptCallbacks;
+    bool interruptCallbackDisabled;
+
+    JSGetIncumbentGlobalCallback getIncumbentGlobalCallback;
+    JSEnqueuePromiseJobCallback enqueuePromiseJobCallback;
+    void* enqueuePromiseJobCallbackData;
+
+    JSPromiseRejectionTrackerCallback promiseRejectionTrackerCallback;
+    void* promiseRejectionTrackerCallbackData;
+
+    JS::StartAsyncTaskCallback startAsyncTaskCallback;
+    JS::FinishAsyncTaskCallback finishAsyncTaskCallback;
+    js::ExclusiveData<js::PromiseTaskPtrVector> promiseTasksToDestroy;
+
+  private:
+    /*
+     * Lock taken when using per-runtime or per-zone data that could otherwise
+     * be accessed simultaneously by both the main thread and another thread
+     * with an ExclusiveContext.
+     *
+     * Locking this only occurs if there is actually a thread other than the
+     * main thread with an ExclusiveContext which could access such data.
+     */
+    js::Mutex exclusiveAccessLock;
+#ifdef DEBUG
+    bool mainThreadHasExclusiveAccess;
+#endif
+
+    /* Number of non-main threads with an ExclusiveContext. */
+    size_t numExclusiveThreads;
+
+    friend class js::AutoLockForExclusiveAccess;
+
+  public:
+    void setUsedByExclusiveThread(JS::Zone* zone);
+    void clearUsedByExclusiveThread(JS::Zone* zone);
+
+    bool exclusiveThreadsPresent() const {
+        return numExclusiveThreads > 0;
+    }
+
+    // How many compartments there are across all zones. This number includes
+    // ExclusiveContext compartments, so it isn't necessarily equal to the
+    // number of compartments visited by CompartmentsIter.
+    size_t              numCompartments;
+
+    /* Locale-specific callbacks for string conversion. */
+    const JSLocaleCallbacks* localeCallbacks;
+
+    /* Default locale for Internationalization API */
+    char* defaultLocale;
+
+    /* Default JSVersion. */
+    JSVersion defaultVersion_;
+
+    /* Futex state, used by Atomics.wait() and Atomics.wake() on the Atomics object */
+    js::FutexRuntime fx;
+
+  private:
+    /* See comment for JS_AbortIfWrongThread in jsapi.h. */
+    js::Thread::Id ownerThread_;
+    size_t ownerThreadNative_;
+    friend bool js::CurrentThreadCanAccessRuntime(const JSRuntime* rt);
+  public:
+
+    size_t ownerThreadNative() const {
+        return ownerThreadNative_;
+    }
+
+    /* Temporary arena pool used while compiling and decompiling. */
+    static const size_t TEMP_LIFO_ALLOC_PRIMARY_CHUNK_SIZE = 4 * 1024;
+    js::LifoAlloc tempLifoAlloc;
+
+  private:
+    js::jit::JitRuntime* jitRuntime_;
+
+    /*
+     * Self-hosting state cloned on demand into other compartments. Shared with the parent
+     * runtime if there is one.
+     */
+    js::NativeObject* selfHostingGlobal_;
+
+    static js::GlobalObject*
+    createSelfHostingGlobal(JSContext* cx);
+
+    bool getUnclonedSelfHostedValue(JSContext* cx, js::HandlePropertyName name,
+                                    js::MutableHandleValue vp);
+    JSFunction* getUnclonedSelfHostedFunction(JSContext* cx, js::HandlePropertyName name);
+
+    /* Space for interpreter frames. */
+    js::InterpreterStack interpreterStack_;
+
+    js::jit::JitRuntime* createJitRuntime(JSContext* cx);
+
+  public:
+    js::jit::JitRuntime* getJitRuntime(JSContext* cx) {
+        return jitRuntime_ ? jitRuntime_ : createJitRuntime(cx);
+    }
+    js::jit::JitRuntime* jitRuntime() const {
+        return jitRuntime_;
+    }
+    bool hasJitRuntime() const {
+        return !!jitRuntime_;
+    }
+    js::InterpreterStack& interpreterStack() {
+        return interpreterStack_;
+    }
+
+    inline JSContext* unsafeContextFromAnyThread();
+    inline JSContext* contextFromMainThread();
+
+    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:
+    // Used to generate random keys for hash tables.
+    mozilla::Maybe<mozilla::non_crypto::XorShift128PlusRNG> randomKeyGenerator_;
+    mozilla::non_crypto::XorShift128PlusRNG& randomKeyGenerator();
+
+  public:
+    mozilla::HashCodeScrambler randomHashCodeScrambler();
+    mozilla::non_crypto::XorShift128PlusRNG forkRandomKeyGenerator();
+
+    //-------------------------------------------------------------------------
+    // Self-hosting support
+    //-------------------------------------------------------------------------
+
+    bool hasInitializedSelfHosting() const {
+        return selfHostingGlobal_;
+    }
+
+    bool initSelfHosting(JSContext* cx);
+    void finishSelfHosting();
+    void markSelfHostingGlobal(JSTracer* trc);
+    bool isSelfHostingGlobal(JSObject* global) {
+        return global == selfHostingGlobal_;
+    }
+    bool isSelfHostingCompartment(JSCompartment* comp) const;
+    bool isSelfHostingZone(const JS::Zone* zone) const;
+    bool createLazySelfHostedFunctionClone(JSContext* cx, js::HandlePropertyName selfHostedName,
+                                           js::HandleAtom name, unsigned nargs,
+                                           js::HandleObject proto,
+                                           js::NewObjectKind newKind,
+                                           js::MutableHandleFunction fun);
+    bool cloneSelfHostedFunctionScript(JSContext* cx, js::Handle<js::PropertyName*> name,
+                                       js::Handle<JSFunction*> targetFun);
+    bool cloneSelfHostedValue(JSContext* cx, js::Handle<js::PropertyName*> name,
+                              js::MutableHandleValue vp);
+    void assertSelfHostedFunctionHasCanonicalName(JSContext* cx, js::HandlePropertyName name);
+
+    //-------------------------------------------------------------------------
+    // Locale information
+    //-------------------------------------------------------------------------
+
+    /*
+     * Set the default locale for the ECMAScript Internationalization API
+     * (Intl.Collator, Intl.NumberFormat, Intl.DateTimeFormat).
+     * Note that the Internationalization API encourages clients to
+     * specify their own locales.
+     * The locale string remains owned by the caller.
+     */
+    bool setDefaultLocale(const char* locale);
+
+    /* Reset the default locale to OS defaults. */
+    void resetDefaultLocale();
+
+    /* Gets current default locale. String remains owned by context. */
+    const char* getDefaultLocale();
+
+    /* Shared Intl data for this runtime. */
+    js::SharedIntlData sharedIntlData;
+
+    void traceSharedIntlData(JSTracer* trc);
+
+    JSVersion defaultVersion() const { return defaultVersion_; }
+    void setDefaultVersion(JSVersion v) { defaultVersion_ = v; }
+
+    /* Base address of the native stack for the current thread. */
+    const uintptr_t     nativeStackBase;
+
+    /* The native stack size limit that runtime should not exceed. */
+    size_t              nativeStackQuota[js::StackKindCount];
+
+    /* Compartment destroy callback. */
+    JSDestroyCompartmentCallback destroyCompartmentCallback;
+
+    /* Compartment memory reporting callback. */
+    JSSizeOfIncludingThisCompartmentCallback sizeOfIncludingThisCompartmentCallback;
+
+    /* Zone destroy callback. */
+    JSZoneCallback destroyZoneCallback;
+
+    /* Zone sweep callback. */
+    JSZoneCallback sweepZoneCallback;
+
+    /* Call this to get the name of a compartment. */
+    JSCompartmentNameCallback compartmentNameCallback;
+
+    js::ActivityCallback  activityCallback;
+    void*                activityCallbackArg;
+    void triggerActivityCallback(bool active);
+
+    /* The request depth for this thread. */
+    unsigned            requestDepth;
+
+#ifdef DEBUG
+    unsigned            checkRequestDepth;
+#endif
+
+    /* Garbage collector state, used by jsgc.c. */
+    js::gc::GCRuntime   gc;
+
+    /* Garbage collector state has been successfully initialized. */
+    bool                gcInitialized;
+
+    bool hasZealMode(js::gc::ZealMode mode) { return gc.hasZealMode(mode); }
+
+    void lockGC() {
+        gc.lockGC();
+    }
+
+    void unlockGC() {
+        gc.unlockGC();
+    }
+
+#ifdef JS_SIMULATOR
+    js::jit::Simulator* simulator_;
+#endif
+
+  public:
+#ifdef JS_SIMULATOR
+    js::jit::Simulator* simulator() const;
+    uintptr_t* addressOfSimulatorStackLimit();
+#endif
+
+    /* Strong references on scripts held for PCCount profiling API. */
+    JS::PersistentRooted<js::ScriptAndCountsVector>* scriptAndCountsVector;
+
+    /* Code coverage output. */
+    js::coverage::LCovRuntime lcovOutput;
+
+    /* Well-known numbers. */
+    const js::Value     NaNValue;
+    const js::Value     negativeInfinityValue;
+    const js::Value     positiveInfinityValue;
+
+    js::PropertyName*   emptyString;
+
+    mozilla::UniquePtr<js::SourceHook> sourceHook;
+
+    /* SPS profiling metadata */
+    js::SPSProfiler     spsProfiler;
+
+    /* If true, new scripts must be created with PC counter information. */
+    bool                profilingScripts;
+
+    /* 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;
+    }
+
+    /* Had an out-of-memory error which did not populate an exception. */
+    bool                hadOutOfMemory;
+
+#if defined(DEBUG) || defined(JS_OOM_BREAKPOINT)
+    /* We are currently running a simulated OOM test. */
+    bool runningOOMTest;
+#endif
+
+    /*
+     * Allow relazifying functions in compartments that are active. This is
+     * only used by the relazifyFunctions() testing function.
+     */
+    bool                allowRelazificationForTesting;
+
+    /* Linked list of all Debugger objects in the runtime. */
+    mozilla::LinkedList<js::Debugger> debuggerList;
+
+    /*
+     * Head of circular list of all enabled Debuggers that have
+     * onNewGlobalObject handler methods established.
+     */
+    JSCList             onNewGlobalObjectWatchers;
+
+#if defined(XP_DARWIN)
+    js::wasm::MachExceptionHandler wasmMachExceptionHandler;
+#endif
+
+  private:
+    js::FreeOp*         defaultFreeOp_;
+
+  public:
+    js::FreeOp* defaultFreeOp() {
+        MOZ_ASSERT(defaultFreeOp_);
+        return defaultFreeOp_;
+    }
+
+    uint32_t            debuggerMutations;
+
+    const JSSecurityCallbacks* securityCallbacks;
+    const js::DOMCallbacks* DOMcallbacks;
+    JSDestroyPrincipalsOp destroyPrincipals;
+    JSReadPrincipalsOp readPrincipals;
+
+    /* Optional warning reporter. */
+    JS::WarningReporter warningReporter;
+
+    JS::BuildIdOp buildIdOp;
+
+    /* AsmJSCache callbacks are runtime-wide. */
+    JS::AsmJSCacheOps   asmJSCacheOps;
+
+    /*
+     * The propertyRemovals counter is incremented for every JSObject::clear,
+     * and for each JSObject::remove method call that frees a slot in the given
+     * object. See js_NativeGet and js_NativeSet in jsobj.cpp.
+     */
+    uint32_t            propertyRemovals;
+
+#if !EXPOSE_INTL_API
+    /* Number localization, used by jsnum.cpp. */
+    const char*         thousandsSeparator;
+    const char*         decimalSeparator;
+    const char*         numGrouping;
+#endif
+
+  private:
+    mozilla::Maybe<js::SharedImmutableStringsCache> sharedImmutableStrings_;
+
+  public:
+    // If this particular JSRuntime has a SharedImmutableStringsCache, return a
+    // pointer to it, otherwise return nullptr.
+    js::SharedImmutableStringsCache* maybeThisRuntimeSharedImmutableStrings() {
+        return sharedImmutableStrings_.isSome() ? &*sharedImmutableStrings_ : nullptr;
+    }
+
+    // Get a reference to this JSRuntime's or its parent's
+    // SharedImmutableStringsCache.
+    js::SharedImmutableStringsCache& sharedImmutableStrings() {
+        MOZ_ASSERT_IF(parentRuntime, !sharedImmutableStrings_);
+        MOZ_ASSERT_IF(!parentRuntime, sharedImmutableStrings_);
+        return parentRuntime ? parentRuntime->sharedImmutableStrings() : *sharedImmutableStrings_;
+    }
+
+    // Count of AutoKeepAtoms instances on the main thread's stack. When any
+    // instances exist, atoms in the runtime will not be collected. Threads
+    // with an ExclusiveContext do not increment this value, but the presence
+    // of any such threads also inhibits collection of atoms. We don't scan the
+    // stacks of exclusive threads, so we need to avoid collecting their
+    // objects in another way. The only GC thing pointers they have are to
+    // their exclusive compartment (which is not collected) or to the atoms
+    // compartment. Therefore, we avoid collecting the atoms compartment when
+    // exclusive threads are running.
+  private:
+    unsigned keepAtoms_;
+    friend class js::AutoKeepAtoms;
+  public:
+    bool keepAtoms() {
+        return keepAtoms_ != 0 || exclusiveThreadsPresent();
+    }
+
+  private:
+    const JSPrincipals* trustedPrincipals_;
+  public:
+    void setTrustedPrincipals(const JSPrincipals* p) { trustedPrincipals_ = p; }
+    const JSPrincipals* trustedPrincipals() const { return trustedPrincipals_; }
+
+  private:
+    bool beingDestroyed_;
+  public:
+    bool isBeingDestroyed() const {
+        return beingDestroyed_;
+    }
+
+  private:
+    // Set of all atoms other than those in permanentAtoms and staticStrings.
+    // Reading or writing this set requires the calling thread to have an
+    // ExclusiveContext and hold a lock. Use AutoLockForExclusiveAccess.
+    js::AtomSet* atoms_;
+
+    // Compartment and associated zone containing all atoms in the runtime, as
+    // well as runtime wide IonCode stubs. Modifying the contents of this
+    // compartment requires the calling thread to have an ExclusiveContext and
+    // hold a lock. Use AutoLockForExclusiveAccess.
+    JSCompartment* atomsCompartment_;
+
+    // Set of all live symbols produced by Symbol.for(). All such symbols are
+    // allocated in the atomsCompartment. Reading or writing the symbol
+    // registry requires the calling thread to have an ExclusiveContext and
+    // hold a lock. Use AutoLockForExclusiveAccess.
+    js::SymbolRegistry symbolRegistry_;
+
+  public:
+    bool initializeAtoms(JSContext* cx);
+    void finishAtoms();
+    bool atomsAreFinished() const { return !atoms_; }
+
+    void sweepAtoms();
+
+    js::AtomSet& atoms(js::AutoLockForExclusiveAccess& lock) {
+        return *atoms_;
+    }
+    JSCompartment* atomsCompartment(js::AutoLockForExclusiveAccess& lock) {
+        return atomsCompartment_;
+    }
+
+    bool isAtomsCompartment(JSCompartment* comp) {
+        return comp == atomsCompartment_;
+    }
+
+    // The atoms compartment is the only one in its zone.
+    inline bool isAtomsZone(const JS::Zone* zone) const;
+
+    bool activeGCInAtomsZone();
+
+    js::SymbolRegistry& symbolRegistry(js::AutoLockForExclusiveAccess& lock) {
+        return symbolRegistry_;
+    }
+
+    // Permanent atoms are fixed during initialization of the runtime and are
+    // not modified or collected until the runtime is destroyed. These may be
+    // shared with another, longer living runtime through |parentRuntime| and
+    // can be freely accessed with no locking necessary.
+
+    // Permanent atoms pre-allocated for general use.
+    js::StaticStrings* staticStrings;
+
+    // Cached pointers to various permanent property names.
+    JSAtomState* commonNames;
+
+    // All permanent atoms in the runtime, other than those in staticStrings.
+    // Unlike |atoms_|, access to this does not require
+    // AutoLockForExclusiveAccess because it is frozen and thus read-only.
+    js::FrozenAtomSet* permanentAtoms;
+
+    bool transformToPermanentAtoms(JSContext* cx);
+
+    // Cached well-known symbols (ES6 rev 24 6.1.5.1). Like permanent atoms,
+    // these are shared with the parentRuntime, if any.
+    js::WellKnownSymbols* wellKnownSymbols;
+
+    const JSWrapObjectCallbacks*           wrapObjectCallbacks;
+    js::PreserveWrapperCallback            preserveWrapperCallback;
+
+    // Table of bytecode and other data that may be shared across scripts
+    // within the runtime. This may be modified by threads with an
+    // ExclusiveContext and requires a lock.
+  private:
+    js::ScriptDataTable scriptDataTable_;
+  public:
+    js::ScriptDataTable& scriptDataTable(js::AutoLockForExclusiveAccess& lock) {
+        return scriptDataTable_;
+    }
+
+    bool jitSupportsFloatingPoint;
+    bool jitSupportsUnalignedAccesses;
+    bool jitSupportsSimd;
+
+    // Cache for jit::GetPcScript().
+    js::jit::PcScriptCache* ionPcScriptCache;
+
+    js::ScriptEnvironmentPreparer* scriptEnvironmentPreparer;
+
+    js::CTypesActivityCallback  ctypesActivityCallback;
+
+  private:
+    static mozilla::Atomic<size_t> liveRuntimesCount;
+
+  public:
+    static bool hasLiveRuntimes() {
+        return liveRuntimesCount > 0;
+    }
+
+  protected:
+    explicit JSRuntime(JSRuntime* parentRuntime);
+
+    // destroyRuntime is used instead of a destructor, to ensure the downcast
+    // to JSContext remains valid. The final GC triggered here depends on this.
+    void destroyRuntime();
+
+    bool init(uint32_t maxbytes, uint32_t maxNurseryBytes);
+
+    JSRuntime* thisFromCtor() { return this; }
+
+  public:
+    /*
+     * Call this after allocating memory held by GC things, to update memory
+     * pressure counters or report the OOM error if necessary. If oomError and
+     * cx is not null the function also reports OOM error.
+     *
+     * The function must be called outside the GC lock and in case of OOM error
+     * the caller must ensure that no deadlock possible during OOM reporting.
+     */
+    void updateMallocCounter(size_t nbytes);
+    void updateMallocCounter(JS::Zone* zone, size_t nbytes);
+
+    void reportAllocationOverflow() { js::ReportAllocationOverflow(nullptr); }
+
+    /*
+     * This should be called after system malloc/calloc/realloc returns nullptr
+     * to try to recove some memory or to report an error.  For realloc, the
+     * original pointer must be passed as reallocPtr.
+     *
+     * The function must be called outside the GC lock.
+     */
+    JS_FRIEND_API(void*) onOutOfMemory(js::AllocFunction allocator, size_t nbytes,
+                                       void* reallocPtr = nullptr, JSContext* maybecx = nullptr);
+
+    /*  onOutOfMemory but can call the largeAllocationFailureCallback. */
+    JS_FRIEND_API(void*) onOutOfMemoryCanGC(js::AllocFunction allocator, size_t nbytes,
+                                            void* reallocPtr = nullptr);
+
+    void addSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf, JS::RuntimeSizes* runtime);
+
+  private:
+    const js::Class* windowProxyClass_;
+
+    // Settings for how helper threads can be used.
+    bool offthreadIonCompilationEnabled_;
+    bool parallelParsingEnabled_;
+
+    bool autoWritableJitCodeActive_;
+
+  public:
+
+    // Note: these values may be toggled dynamically (in response to about:config
+    // prefs changing).
+    void setOffthreadIonCompilationEnabled(bool value) {
+        offthreadIonCompilationEnabled_ = value;
+    }
+    bool canUseOffthreadIonCompilation() const {
+        return offthreadIonCompilationEnabled_;
+    }
+    void setParallelParsingEnabled(bool value) {
+        parallelParsingEnabled_ = value;
+    }
+    bool canUseParallelParsing() const {
+        return parallelParsingEnabled_;
+    }
+
+    void toggleAutoWritableJitCodeActive(bool b) {
+        MOZ_ASSERT(autoWritableJitCodeActive_ != b, "AutoWritableJitCode should not be nested.");
+        MOZ_ASSERT(CurrentThreadCanAccessRuntime(this));
+        autoWritableJitCodeActive_ = b;
+    }
+
+    const js::Class* maybeWindowProxyClass() const {
+        return windowProxyClass_;
+    }
+    void setWindowProxyClass(const js::Class* clasp) {
+        windowProxyClass_ = clasp;
+    }
+
+#ifdef DEBUG
+  public:
+    js::AutoEnterPolicy* enteredPolicy;
+#endif
+
+    /* See comment for JS::SetLargeAllocationFailureCallback in jsapi.h. */
+    JS::LargeAllocationFailureCallback largeAllocationFailureCallback;
+    void* largeAllocationFailureCallbackData;
+
+    /* See comment for JS::SetOutOfMemoryCallback in jsapi.h. */
+    JS::OutOfMemoryCallback oomCallback;
+    void* oomCallbackData;
+
+    /*
+     * These variations of malloc/calloc/realloc will call the
+     * large-allocation-failure callback on OOM and retry the allocation.
+     */
+
+    static const unsigned LARGE_ALLOCATION = 25 * 1024 * 1024;
+
+    template <typename T>
+    T* pod_callocCanGC(size_t numElems) {
+        T* p = pod_calloc<T>(numElems);
+        if (MOZ_LIKELY(!!p))
+            return p;
+        size_t bytes;
+        if (MOZ_UNLIKELY(!js::CalculateAllocSize<T>(numElems, &bytes))) {
+            reportAllocationOverflow();
+            return nullptr;
+        }
+        return static_cast<T*>(onOutOfMemoryCanGC(js::AllocFunction::Calloc, bytes));
+    }
+
+    template <typename T>
+    T* pod_reallocCanGC(T* p, size_t oldSize, size_t newSize) {
+        T* p2 = pod_realloc<T>(p, oldSize, newSize);
+        if (MOZ_LIKELY(!!p2))
+            return p2;
+        size_t bytes;
+        if (MOZ_UNLIKELY(!js::CalculateAllocSize<T>(newSize, &bytes))) {
+            reportAllocationOverflow();
+            return nullptr;
+        }
+        return static_cast<T*>(onOutOfMemoryCanGC(js::AllocFunction::Realloc, bytes, p));
+    }
+
+    /*
+     * Debugger.Memory functions like takeCensus use this embedding-provided
+     * function to assess the size of malloc'd blocks of memory.
+     */
+    mozilla::MallocSizeOf debuggerMallocSizeOf;
+
+    /* Last time at which an animation was played for this runtime. */
+    int64_t lastAnimationTime;
+
+  public:
+    js::PerformanceMonitoring performanceMonitoring;
+
+  private:
+    /* List of Ion compilation waiting to get linked. */
+    typedef mozilla::LinkedList<js::jit::IonBuilder> IonBuilderList;
+
+    IonBuilderList ionLazyLinkList_;
+    size_t ionLazyLinkListSize_;
+
+  public:
+    IonBuilderList& ionLazyLinkList();
+
+    size_t ionLazyLinkListSize() {
+        return ionLazyLinkListSize_;
+    }
+
+    void ionLazyLinkListRemove(js::jit::IonBuilder* builder);
+    void ionLazyLinkListAdd(js::jit::IonBuilder* builder);
+
+  private:
+    /* The stack format for the current runtime.  Only valid on non-child
+     * runtimes. */
+    mozilla::Atomic<js::StackFormat, mozilla::ReleaseAcquire> stackFormat_;
+
+  public:
+    js::StackFormat stackFormat() const {
+        const JSRuntime* rt = this;
+        while (rt->parentRuntime) {
+            MOZ_ASSERT(rt->stackFormat_ == js::StackFormat::Default);
+            rt = rt->parentRuntime;
+        }
+        MOZ_ASSERT(rt->stackFormat_ != js::StackFormat::Default);
+        return rt->stackFormat_;
+    }
+    void setStackFormat(js::StackFormat format) {
+        MOZ_ASSERT(!parentRuntime);
+        MOZ_ASSERT(format != js::StackFormat::Default);
+        stackFormat_ = format;
+    }
+
+    // For inherited heap state accessors.
+    friend class js::gc::AutoTraceSession;
+    friend class JS::AutoEnterCycleCollection;
+};
+
+namespace js {
+
+static inline JSContext*
+GetJSContextFromMainThread()
+{
+    return js::TlsPerThreadData.get()->contextFromMainThread();
+}
+
+/*
+ * Flags accompany script version data so that a) dynamically created scripts
+ * can inherit their caller's compile-time properties and b) scripts can be
+ * appropriately compared in the eval cache across global option changes. An
+ * example of the latter is enabling the top-level-anonymous-function-is-error
+ * option: subsequent evals of the same, previously-valid script text may have
+ * become invalid.
+ */
+namespace VersionFlags {
+static const unsigned MASK      = 0x0FFF; /* see JSVersion in jspubtd.h */
+} /* namespace VersionFlags */
+
+static inline JSVersion
+VersionNumber(JSVersion version)
+{
+    return JSVersion(uint32_t(version) & VersionFlags::MASK);
+}
+
+static inline JSVersion
+VersionExtractFlags(JSVersion version)
+{
+    return JSVersion(uint32_t(version) & ~VersionFlags::MASK);
+}
+
+static inline void
+VersionCopyFlags(JSVersion* version, JSVersion from)
+{
+    *version = JSVersion(VersionNumber(*version) | VersionExtractFlags(from));
+}
+
+static inline bool
+VersionHasFlags(JSVersion version)
+{
+    return !!VersionExtractFlags(version);
+}
+
+static inline bool
+VersionIsKnown(JSVersion version)
+{
+    return VersionNumber(version) != JSVERSION_UNKNOWN;
+}
+
+inline void
+FreeOp::free_(void* p)
+{
+    js_free(p);
+}
+
+inline void
+FreeOp::freeLater(void* p)
+{
+    // FreeOps other than the defaultFreeOp() are constructed on the stack,
+    // and won't hold onto the pointers to free indefinitely.
+    MOZ_ASSERT(!isDefaultFreeOp());
+
+    AutoEnterOOMUnsafeRegion oomUnsafe;
+    if (!freeLaterList.append(p))
+        oomUnsafe.crash("FreeOp::freeLater");
+}
+
+inline bool
+FreeOp::appendJitPoisonRange(const jit::JitPoisonRange& range)
+{
+    // FreeOps other than the defaultFreeOp() are constructed on the stack,
+    // and won't hold onto the pointers to free indefinitely.
+    MOZ_ASSERT(!isDefaultFreeOp());
+
+    return jitPoisonRanges.append(range);
+}
+
+/*
+ * RAII class that takes the GC lock while it is live.
+ *
+ * Note that the lock may be temporarily released by use of AutoUnlockGC when
+ * passed a non-const reference to this class.
+ */
+class MOZ_RAII AutoLockGC
+{
+  public:
+    explicit AutoLockGC(JSRuntime* rt
+                        MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+      : runtime_(rt)
+    {
+        MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+        lock();
+    }
+
+    ~AutoLockGC() {
+        unlock();
+    }
+
+    void lock() {
+        MOZ_ASSERT(lockGuard_.isNothing());
+        lockGuard_.emplace(runtime_->gc.lock);
+    }
+
+    void unlock() {
+        MOZ_ASSERT(lockGuard_.isSome());
+        lockGuard_.reset();
+    }
+
+    js::LockGuard<js::Mutex>& guard() {
+        return lockGuard_.ref();
+    }
+
+  private:
+    JSRuntime* runtime_;
+    mozilla::Maybe<js::LockGuard<js::Mutex>> lockGuard_;
+    MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+
+    AutoLockGC(const AutoLockGC&) = delete;
+    AutoLockGC& operator=(const AutoLockGC&) = delete;
+};
+
+class MOZ_RAII AutoUnlockGC
+{
+  public:
+    explicit AutoUnlockGC(AutoLockGC& lock
+                          MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+      : lock(lock)
+    {
+        MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+        lock.unlock();
+    }
+
+    ~AutoUnlockGC() {
+        lock.lock();
+    }
+
+  private:
+    AutoLockGC& lock;
+    MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+
+    AutoUnlockGC(const AutoUnlockGC&) = delete;
+    AutoUnlockGC& operator=(const AutoUnlockGC&) = delete;
+};
+
+class MOZ_RAII AutoKeepAtoms
+{
+    PerThreadData* pt;
+    MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+
+  public:
+    explicit AutoKeepAtoms(PerThreadData* pt
+                           MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+      : pt(pt)
+    {
+        MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+        if (JSRuntime* rt = pt->runtimeIfOnOwnerThread()) {
+            rt->keepAtoms_++;
+        } else {
+            // This should be a thread with an exclusive context, which will
+            // always inhibit collection of atoms.
+            MOZ_ASSERT(pt->exclusiveThreadsPresent());
+        }
+    }
+    ~AutoKeepAtoms() {
+        if (JSRuntime* rt = pt->runtimeIfOnOwnerThread()) {
+            MOZ_ASSERT(rt->keepAtoms_);
+            rt->keepAtoms_--;
+            if (rt->gc.fullGCForAtomsRequested() && !rt->keepAtoms())
+                rt->gc.triggerFullGCForAtoms();
+        }
+    }
+};
+
+inline JSRuntime*
+PerThreadData::runtimeFromMainThread()
+{
+    MOZ_ASSERT(CurrentThreadCanAccessRuntime(runtime_));
+    return runtime_;
+}
+
+inline JSRuntime*
+PerThreadData::runtimeIfOnOwnerThread()
+{
+    return (runtime_ && CurrentThreadCanAccessRuntime(runtime_)) ? runtime_ : nullptr;
+}
+
+inline bool
+PerThreadData::exclusiveThreadsPresent()
+{
+    return runtime_->exclusiveThreadsPresent();
+}
+
+/************************************************************************/
+
+static MOZ_ALWAYS_INLINE void
+MakeRangeGCSafe(Value* vec, size_t len)
+{
+    mozilla::PodZero(vec, len);
+}
+
+static MOZ_ALWAYS_INLINE void
+MakeRangeGCSafe(Value* beg, Value* end)
+{
+    mozilla::PodZero(beg, end - beg);
+}
+
+static MOZ_ALWAYS_INLINE void
+MakeRangeGCSafe(jsid* beg, jsid* end)
+{
+    for (jsid* id = beg; id != end; ++id)
+        *id = INT_TO_JSID(0);
+}
+
+static MOZ_ALWAYS_INLINE void
+MakeRangeGCSafe(jsid* vec, size_t len)
+{
+    MakeRangeGCSafe(vec, vec + len);
+}
+
+static MOZ_ALWAYS_INLINE void
+MakeRangeGCSafe(Shape** beg, Shape** end)
+{
+    mozilla::PodZero(beg, end - beg);
+}
+
+static MOZ_ALWAYS_INLINE void
+MakeRangeGCSafe(Shape** vec, size_t len)
+{
+    mozilla::PodZero(vec, len);
+}
+
+static MOZ_ALWAYS_INLINE void
+SetValueRangeToUndefined(Value* beg, Value* end)
+{
+    for (Value* v = beg; v != end; ++v)
+        v->setUndefined();
+}
+
+static MOZ_ALWAYS_INLINE void
+SetValueRangeToUndefined(Value* vec, size_t len)
+{
+    SetValueRangeToUndefined(vec, vec + len);
+}
+
+static MOZ_ALWAYS_INLINE void
+SetValueRangeToNull(Value* beg, Value* end)
+{
+    for (Value* v = beg; v != end; ++v)
+        v->setNull();
+}
+
+static MOZ_ALWAYS_INLINE void
+SetValueRangeToNull(Value* vec, size_t len)
+{
+    SetValueRangeToNull(vec, vec + len);
+}
+
+/*
+ * Allocation policy that uses JSRuntime::pod_malloc and friends, so that
+ * memory pressure is properly accounted for. This is suitable for
+ * long-lived objects owned by the JSRuntime.
+ *
+ * Since it doesn't hold a JSContext (those may not live long enough), it
+ * can't report out-of-memory conditions itself; the caller must check for
+ * OOM and take the appropriate action.
+ *
+ * FIXME bug 647103 - replace these *AllocPolicy names.
+ */
+class RuntimeAllocPolicy
+{
+    JSRuntime* const runtime;
+
+  public:
+    MOZ_IMPLICIT RuntimeAllocPolicy(JSRuntime* rt) : runtime(rt) {}
+
+    template <typename T>
+    T* maybe_pod_malloc(size_t numElems) {
+        return runtime->maybe_pod_malloc<T>(numElems);
+    }
+
+    template <typename T>
+    T* maybe_pod_calloc(size_t numElems) {
+        return runtime->maybe_pod_calloc<T>(numElems);
+    }
+
+    template <typename T>
+    T* maybe_pod_realloc(T* p, size_t oldSize, size_t newSize) {
+        return runtime->maybe_pod_realloc<T>(p, oldSize, newSize);
+    }
+
+    template <typename T>
+    T* pod_malloc(size_t numElems) {
+        return runtime->pod_malloc<T>(numElems);
+    }
+
+    template <typename T>
+    T* pod_calloc(size_t numElems) {
+        return runtime->pod_calloc<T>(numElems);
+    }
+
+    template <typename T>
+    T* pod_realloc(T* p, size_t oldSize, size_t newSize) {
+        return runtime->pod_realloc<T>(p, oldSize, newSize);
+    }
+
+    void free_(void* p) { js_free(p); }
+    void reportAllocOverflow() const {}
+
+    bool checkSimulatedOOM() const {
+        return !js::oom::ShouldFailWithOOM();
+    }
+};
+
+extern const JSSecurityCallbacks NullSecurityCallbacks;
+
+// Debugging RAII class which marks the current thread as performing an Ion
+// compilation, for use by CurrentThreadCan{Read,Write}CompilationData
+class MOZ_RAII AutoEnterIonCompilation
+{
+  public:
+    explicit AutoEnterIonCompilation(bool safeForMinorGC
+                                     MOZ_GUARD_OBJECT_NOTIFIER_PARAM) {
+        MOZ_GUARD_OBJECT_NOTIFIER_INIT;
+
+#ifdef DEBUG
+        PerThreadData* pt = js::TlsPerThreadData.get();
+        MOZ_ASSERT(!pt->ionCompiling);
+        MOZ_ASSERT(!pt->ionCompilingSafeForMinorGC);
+        pt->ionCompiling = true;
+        pt->ionCompilingSafeForMinorGC = safeForMinorGC;
+#endif
+    }
+
+    ~AutoEnterIonCompilation() {
+#ifdef DEBUG
+        PerThreadData* pt = js::TlsPerThreadData.get();
+        MOZ_ASSERT(pt->ionCompiling);
+        pt->ionCompiling = false;
+        pt->ionCompilingSafeForMinorGC = false;
+#endif
+    }
+
+    MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
+};
+
+namespace gc {
+
+// In debug builds, set/unset the performing GC flag for the current thread.
+struct MOZ_RAII AutoSetThreadIsPerformingGC
+{
+#ifdef DEBUG
+    AutoSetThreadIsPerformingGC()
+      : threadData_(js::TlsPerThreadData.get())
+    {
+        MOZ_ASSERT(!threadData_->performingGC);
+        threadData_->performingGC = true;
+    }
+
+    ~AutoSetThreadIsPerformingGC() {
+        MOZ_ASSERT(threadData_->performingGC);
+        threadData_->performingGC = false;
+    }
+
+  private:
+    PerThreadData* threadData_;
+#else
+    AutoSetThreadIsPerformingGC() {}
+#endif
+};
+
+// In debug builds, set/unset the GC sweeping flag for the current thread.
+struct MOZ_RAII AutoSetThreadIsSweeping
+{
+#ifdef DEBUG
+    AutoSetThreadIsSweeping()
+      : threadData_(js::TlsPerThreadData.get())
+    {
+        MOZ_ASSERT(!threadData_->gcSweeping);
+        threadData_->gcSweeping = true;
+    }
+
+    ~AutoSetThreadIsSweeping() {
+        MOZ_ASSERT(threadData_->gcSweeping);
+        threadData_->gcSweeping = false;
+    }
+
+  private:
+    PerThreadData* threadData_;
+#else
+    AutoSetThreadIsSweeping() {}
+#endif
+};
+
+} // namespace gc
+
+/*
+ * Provides a delete policy that can be used for objects which have their
+ * lifetime managed by the GC and can only safely be destroyed while the nursery
+ * is empty.
+ *
+ * This is necessary when initializing such an object may fail after the initial
+ * allocation.  The partially-initialized object must be destroyed, but it may
+ * not be safe to do so at the current time.  This policy puts the object on a
+ * queue to be destroyed at a safe time.
+ */
+template <typename T>
+struct GCManagedDeletePolicy
+{
+    void operator()(const T* ptr) {
+        if (ptr) {
+            JSRuntime* rt = TlsPerThreadData.get()->runtimeIfOnOwnerThread();
+            if (rt && rt->gc.nursery.isEnabled()) {
+                // The object may contain nursery pointers and must only be
+                // destroyed after a minor GC.
+                rt->gc.callAfterMinorGC(deletePtr, const_cast<T*>(ptr));
+            } else {
+                // The object cannot contain nursery pointers so can be
+                // destroyed immediately.
+                gc::AutoSetThreadIsSweeping threadIsSweeping;
+                js_delete(const_cast<T*>(ptr));
+            }
+        }
+    }
+
+  private:
+    static void deletePtr(void* data) {
+        js_delete(reinterpret_cast<T*>(data));
+    }
+};
+
+} /* namespace js */
+
+namespace JS {
+
+template <typename T>
+struct DeletePolicy<js::GCPtr<T>> : public js::GCManagedDeletePolicy<js::GCPtr<T>>
+{};
+
+// Scope data that contain GCPtrs must use the correct DeletePolicy.
+//
+// This is defined here because vm/Scope.h cannot #include "vm/Runtime.h"
+
+template <>
+struct DeletePolicy<js::FunctionScope::Data>
+  : public js::GCManagedDeletePolicy<js::FunctionScope::Data>
+{ };
+
+template <>
+struct DeletePolicy<js::ModuleScope::Data>
+  : public js::GCManagedDeletePolicy<js::ModuleScope::Data>
+{ };
+
+} /* namespace JS */
+
+#ifdef _MSC_VER
+#pragma warning(pop)
+#endif
+
+#endif /* vm_Runtime_h */