The Tor Browser: js/src/vm/Runtime.h@129ffea94266 (annotated)

js/src/vm/Runtime.h@129ffea94266 (annotated)

js/src/vm/Runtime.h

Sat, 03 Jan 2015 20:18:00 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Sat, 03 Jan 2015 20:18:00 +0100
branch: TOR_BUG_3246
changeset 7: 129ffea94266
permissions: -rw-r--r--

Conditionally enable double key logic according to:
private browsing mode or privacy.thirdparty.isolate preference and
implement in GetCookieStringCommon and FindCookie where it counts...
With some reservations of how to convince FindCookie users to test
condition and pass a nullptr when disabling double key logic.

 /* -*- 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 <setjmp.h>
 #include "jsatom.h"
 #include "jsclist.h"
 #include "jsgc.h"
 #ifdef DEBUG
 # include "jsproxy.h"
 #endif
 #include "jsscript.h"
 #include "ds/FixedSizeHash.h"
 #include "frontend/ParseMaps.h"
 #ifdef JSGC_GENERATIONAL
 # include "gc/Nursery.h"
 #endif
 #include "gc/Statistics.h"
 #ifdef JSGC_GENERATIONAL
 # include "gc/StoreBuffer.h"
 #endif
 #include "gc/Tracer.h"
 #ifdef XP_MACOSX
 # include "jit/AsmJSSignalHandlers.h"
 #endif
 #include "js/HashTable.h"
 #include "js/Vector.h"
 #include "vm/CommonPropertyNames.h"
 #include "vm/DateTime.h"
 #include "vm/MallocProvider.h"
 #include "vm/SPSProfiler.h"
 #include "vm/Stack.h"
 #include "vm/ThreadPool.h"
 #ifdef _MSC_VER
 #pragma warning(push)
 #pragma warning(disable:4100) /* Silence unreferenced formal parameter warnings */
 #endif
 namespace js {
 class PerThreadData;
 class ThreadSafeContext;
 class AutoKeepAtoms;
 #ifdef JS_TRACE_LOGGING
 class TraceLogger;
 #endif
 /* Thread Local Storage slot for storing the runtime for a thread. */
 extern mozilla::ThreadLocal<PerThreadData*> TlsPerThreadData;
 } // namespace js
 struct DtoaState;
 extern void
 js_ReportOutOfMemory(js::ThreadSafeContext *cx);
 extern void
 js_ReportAllocationOverflow(js::ThreadSafeContext *cx);
 extern void
 js_ReportOverRecursed(js::ThreadSafeContext *cx);
 namespace JSC { class ExecutableAllocator; }
 namespace WTF { class BumpPointerAllocator; }
 namespace js {
 typedef Rooted<JSLinearString*> RootedLinearString;
 class Activation;
 class ActivationIterator;
 class AsmJSActivation;
 class MathCache;
 namespace jit {
 class JitRuntime;
 class JitActivation;
 struct PcScriptCache;
 class Simulator;
 class SimulatorRuntime;
 class AutoFlushICache;
 }
 /*
  * GetSrcNote cache to avoid O(n^2) growth in finding a source note for a
  * given pc in a script. We use the script->code pointer to tag the cache,
  * instead of the script address itself, so that source notes are always found
  * by offset from the bytecode with which they were generated.
  */
 struct GSNCache {
     typedef HashMap<jsbytecode *,
                     jssrcnote *,
                     PointerHasher<jsbytecode *, 0>,
                     SystemAllocPolicy> Map;
     jsbytecode      *code;
     Map             map;
     GSNCache() : code(nullptr) { }
     void purge();
 };
 /*
  * ScopeCoordinateName cache to avoid O(n^2) growth in finding the name
  * associated with a given aliasedvar operation.
  */
 struct ScopeCoordinateNameCache {
     typedef HashMap<uint32_t,
                     jsid,
                     DefaultHasher<uint32_t>,
                     SystemAllocPolicy> Map;
     Shape *shape;
     Map map;
     ScopeCoordinateNameCache() : shape(nullptr) {}
     void purge();
 };
 typedef Vector<ScriptAndCounts, 0, SystemAllocPolicy> ScriptAndCountsVector;
 struct ConservativeGCData
 {
     /*
      * The GC scans conservatively between ThreadData::nativeStackBase and
      * nativeStackTop unless the latter is nullptr.
      */
     uintptr_t           *nativeStackTop;
     union {
         jmp_buf         jmpbuf;
         uintptr_t       words[JS_HOWMANY(sizeof(jmp_buf), sizeof(uintptr_t))];
     } registerSnapshot;
     ConservativeGCData() {
         mozilla::PodZero(this);
     }
     ~ConservativeGCData() {
 #ifdef JS_THREADSAFE
         /*
          * The conservative GC scanner should be disabled when the thread leaves
          * the last request.
          */
         JS_ASSERT(!hasStackToScan());
 #endif
     }
     MOZ_NEVER_INLINE void recordStackTop();
 #ifdef JS_THREADSAFE
     void updateForRequestEnd() {
         nativeStackTop = nullptr;
     }
 #endif
     bool hasStackToScan() const {
         return !!nativeStackTop;
     }
 };
 struct EvalCacheEntry
 {
     JSScript *script;
     JSScript *callerScript;
     jsbytecode *pc;
 };
 struct EvalCacheLookup
 {
     EvalCacheLookup(JSContext *cx) : str(cx), callerScript(cx) {}
     RootedLinearString str;
     RootedScript callerScript;
     JSVersion version;
     jsbytecode *pc;
 };
 struct EvalCacheHashPolicy
 {
     typedef EvalCacheLookup Lookup;
     static HashNumber hash(const Lookup &l);
     static bool match(const EvalCacheEntry &entry, const EvalCacheLookup &l);
 };
 typedef HashSet<EvalCacheEntry, EvalCacheHashPolicy, SystemAllocPolicy> EvalCache;
 struct LazyScriptHashPolicy
 {
     struct Lookup {
         JSContext *cx;
         LazyScript *lazy;
         Lookup(JSContext *cx, LazyScript *lazy)
           : cx(cx), lazy(lazy)
         {}
     };
     static const size_t NumHashes = 3;
     static void hash(const Lookup &lookup, HashNumber hashes[NumHashes]);
     static bool match(JSScript *script, const Lookup &lookup);
     // Alternate methods for use when removing scripts from the hash without an
     // explicit LazyScript lookup.
     static void hash(JSScript *script, HashNumber hashes[NumHashes]);
     static bool match(JSScript *script, JSScript *lookup) { return script == lookup; }
     static void clear(JSScript **pscript) { *pscript = nullptr; }
     static bool isCleared(JSScript *script) { return !script; }
 };
 typedef FixedSizeHashSet<JSScript *, LazyScriptHashPolicy, 769> LazyScriptCache;
 class PropertyIteratorObject;
 class NativeIterCache
 {
     static const size_t SIZE = size_t(1) << 8;
     /* Cached native iterators. */
     PropertyIteratorObject *data[SIZE];
     static size_t getIndex(uint32_t key) {
         return size_t(key) % SIZE;
     }
   public:
     /* Native iterator most recently started. */
     PropertyIteratorObject *last;
     NativeIterCache()
       : last(nullptr)
     {
         mozilla::PodArrayZero(data);
     }
     void purge() {
         last = nullptr;
         mozilla::PodArrayZero(data);
     }
     PropertyIteratorObject *get(uint32_t key) const {
         return data[getIndex(key)];
     }
     void set(uint32_t key, PropertyIteratorObject *iterobj) {
         data[getIndex(key)] = iterobj;
     }
 };
 /*
  * Cache for speeding up repetitive creation of objects in the VM.
  * When an object is created which matches the criteria in the 'key' section
  * below, an entry is filled with the resulting object.
  */
 class NewObjectCache
 {
     /* Statically asserted to be equal to sizeof(JSObject_Slots16) */
     static const unsigned MAX_OBJ_SIZE = 4 * sizeof(void*) + 16 * sizeof(Value);
     static void staticAsserts() {
         JS_STATIC_ASSERT(NewObjectCache::MAX_OBJ_SIZE == sizeof(JSObject_Slots16));
         JS_STATIC_ASSERT(gc::FINALIZE_OBJECT_LAST == gc::FINALIZE_OBJECT16_BACKGROUND);
     }
     struct Entry
     {
         /* Class of the constructed object. */
         const Class *clasp;
         /*
          * Key with one of three possible values:
          *
          * - Global for the object. The object must have a standard class for
          *   which the global's prototype can be determined, and the object's
          *   parent will be the global.
          *
          * - Prototype for the object (cannot be global). The object's parent
          *   will be the prototype's parent.
          *
          * - Type for the object. The object's parent will be the type's
          *   prototype's parent.
          */
         gc::Cell *key;
         /* Allocation kind for the constructed object. */
         gc::AllocKind kind;
         /* Number of bytes to copy from the template object. */
         uint32_t nbytes;
         /*
          * Template object to copy from, with the initial values of fields,
          * fixed slots (undefined) and private data (nullptr).
          */
         char templateObject[MAX_OBJ_SIZE];
     };
     Entry entries[41];  // TODO: reconsider size
   public:
     typedef int EntryIndex;
     NewObjectCache() { mozilla::PodZero(this); }
     void purge() { mozilla::PodZero(this); }
     /* Remove any cached items keyed on moved objects. */
     void clearNurseryObjects(JSRuntime *rt);
     /*
      * Get the entry index for the given lookup, return whether there was a hit
      * on an existing entry.
      */
     inline bool lookupProto(const Class *clasp, JSObject *proto, gc::AllocKind kind, EntryIndex *pentry);
     inline bool lookupGlobal(const Class *clasp, js::GlobalObject *global, gc::AllocKind kind,
                              EntryIndex *pentry);
     bool lookupType(js::types::TypeObject *type, gc::AllocKind kind, EntryIndex *pentry) {
         return lookup(type->clasp(), type, kind, pentry);
     }
     /*
      * Return a new object from a cache hit produced by a lookup method, or
      * nullptr if returning the object could possibly trigger GC (does not
      * indicate failure).
      */
     template <AllowGC allowGC>
     inline JSObject *newObjectFromHit(JSContext *cx, EntryIndex entry, js::gc::InitialHeap heap);
     /* Fill an entry after a cache miss. */
     void fillProto(EntryIndex entry, const Class *clasp, js::TaggedProto proto, gc::AllocKind kind, JSObject *obj);
     inline void fillGlobal(EntryIndex entry, const Class *clasp, js::GlobalObject *global,
                            gc::AllocKind kind, JSObject *obj);
     void fillType(EntryIndex entry, js::types::TypeObject *type, gc::AllocKind kind,
                   JSObject *obj)
     {
         JS_ASSERT(obj->type() == type);
         return fill(entry, type->clasp(), type, kind, obj);
     }
     /* Invalidate any entries which might produce an object with shape/proto. */
     void invalidateEntriesForShape(JSContext *cx, HandleShape shape, HandleObject proto);
   private:
     bool lookup(const Class *clasp, gc::Cell *key, gc::AllocKind kind, EntryIndex *pentry) {
         uintptr_t hash = (uintptr_t(clasp) ^ uintptr_t(key)) + kind;
         *pentry = hash % mozilla::ArrayLength(entries);
         Entry *entry = &entries[*pentry];
         /* N.B. Lookups with the same clasp/key but different kinds map to different entries. */
         return entry->clasp == clasp && entry->key == key;
     }
     void fill(EntryIndex entry_, const Class *clasp, gc::Cell *key, gc::AllocKind kind, JSObject *obj) {
         JS_ASSERT(unsigned(entry_) < mozilla::ArrayLength(entries));
         Entry *entry = &entries[entry_];
         JS_ASSERT(!obj->hasDynamicSlots() && !obj->hasDynamicElements());
         entry->clasp = clasp;
         entry->key = key;
         entry->kind = kind;
         entry->nbytes = gc::Arena::thingSize(kind);
         js_memcpy(&entry->templateObject, obj, entry->nbytes);
     }
     static void copyCachedToObject(JSObject *dst, JSObject *src, gc::AllocKind kind) {
         js_memcpy(dst, src, gc::Arena::thingSize(kind));
 #ifdef JSGC_GENERATIONAL
         Shape::writeBarrierPost(dst->shape_, &dst->shape_);
         types::TypeObject::writeBarrierPost(dst->type_, &dst->type_);
 #endif
     }
 };
 /*
  * 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 {
     bool        shouldFreeLater_;
   public:
     static FreeOp *get(JSFreeOp *fop) {
         return static_cast<FreeOp *>(fop);
     }
     FreeOp(JSRuntime *rt, bool shouldFreeLater)
       : JSFreeOp(rt),
         shouldFreeLater_(shouldFreeLater)
     {
     }
     bool shouldFreeLater() const {
         return shouldFreeLater_;
     }
     inline void free_(void *p);
     template <class T>
     inline void delete_(T *p) {
         if (p) {
             p->~T();
             free_(p);
         }
     }
     static void staticAsserts() {
         /*
          * Check that JSFreeOp is the first base class for FreeOp and we can
          * reinterpret a pointer to JSFreeOp as a pointer to FreeOp without
          * any offset adjustments. JSClass::finalize <-> Class::finalize depends
          * on this.
          */
         JS_STATIC_ASSERT(offsetof(FreeOp, shouldFreeLater_) == sizeof(JSFreeOp));
     }
 };
 } /* namespace js */
 namespace JS {
 struct RuntimeSizes;
 }
 /* Various built-in or commonly-used names pinned on first context. */
 struct JSAtomState
 {
 #define PROPERTYNAME_FIELD(idpart, id, text) js::FixedHeapPtr<js::PropertyName> id;
     FOR_EACH_COMMON_PROPERTYNAME(PROPERTYNAME_FIELD)
 #undef PROPERTYNAME_FIELD
 #define PROPERTYNAME_FIELD(name, code, init, clasp) js::FixedHeapPtr<js::PropertyName> name;
     JS_FOR_EACH_PROTOTYPE(PROPERTYNAME_FIELD)
 #undef PROPERTYNAME_FIELD
 };
 namespace js {
 #define NAME_OFFSET(name)       offsetof(JSAtomState, name)
 inline HandlePropertyName
 AtomStateOffsetToName(const JSAtomState &atomState, size_t offset)
 {
     return *(js::FixedHeapPtr<js::PropertyName>*)((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,
     WorkerThreadStateLock,
     InterruptLock,
     GCLock
 };
 #ifdef DEBUG
 void AssertCurrentThreadCanLock(RuntimeLock which);
 #else
 inline void AssertCurrentThreadCanLock(RuntimeLock which) {}
 #endif
 /*
  * 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, and for Parallel JS worker
  * threads.
  */
 class PerThreadData : public PerThreadDataFriendFields
 {
     /*
      * 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:
     /*
      * We save all conservative scanned roots in this vector so that
      * conservative scanning can be "replayed" deterministically. In DEBUG mode,
      * this allows us to run a non-incremental GC after every incremental GC to
      * ensure that no objects were missed.
      */
 #ifdef DEBUG
     struct SavedGCRoot {
         void *thing;
         JSGCTraceKind kind;
         SavedGCRoot(void *thing, JSGCTraceKind kind) : thing(thing), kind(kind) {}
     };
     js::Vector<SavedGCRoot, 0, js::SystemAllocPolicy> gcSavedRoots;
 #endif
     /*
      * If Ion code is on the stack, and has called into C++, this will be
      * aligned to an Ion exit frame.
      */
     uint8_t             *ionTop;
     /*
      * The current JSContext when entering JIT code. This field may only be used
      * from JIT code and C++ directly called by JIT code (otherwise it may refer
      * to the wrong JSContext).
      */
     JSContext           *jitJSContext;
     /*
      * The stack limit checked by JIT code. This stack limit may be temporarily
      * set to null to force JIT code to exit (e.g., for the operation callback).
      */
     uintptr_t            jitStackLimit;
     inline void setJitStackLimit(uintptr_t limit);
 #ifdef JS_TRACE_LOGGING
     TraceLogger         *traceLogger;
 #endif
     /*
      * asm.js maintains a stack of AsmJSModule activations (see AsmJS.h). This
      * stack is used by JSRuntime::requestInterrupt to stop long-running asm.js
      * without requiring dynamic polling operations in the generated
      * code. Since requestInterrupt may run on a separate thread than the
      * JSRuntime's owner thread all reads/writes must be synchronized (by
      * rt->interruptLock).
      */
   private:
     friend class js::Activation;
     friend class js::ActivationIterator;
     friend class js::jit::JitActivation;
     friend class js::AsmJSActivation;
 #ifdef DEBUG
     friend void js::AssertCurrentThreadCanLock(RuntimeLock which);
 #endif
     /*
      * Points to the most recent activation running on the thread.
      * See Activation comment in vm/Stack.h.
      */
     js::Activation *activation_;
     /* See AsmJSActivation comment. Protected by rt->interruptLock. */
     js::AsmJSActivation *asmJSActivationStack_;
     /* Pointer to the current AutoFlushICache. */
     js::jit::AutoFlushICache *autoFlushICache_;
 #ifdef JS_ARM_SIMULATOR
     js::jit::Simulator *simulator_;
     uintptr_t simulatorStackLimit_;
 #endif
   public:
     js::Activation *const *addressOfActivation() const {
         return &activation_;
     }
     static unsigned offsetOfAsmJSActivationStackReadOnly() {
         return offsetof(PerThreadData, asmJSActivationStack_);
     }
     static unsigned offsetOfActivation() {
         return offsetof(PerThreadData, activation_);
     }
     js::AsmJSActivation *asmJSActivationStackFromAnyThread() const {
         return asmJSActivationStack_;
     }
     js::AsmJSActivation *asmJSActivationStackFromOwnerThread() const {
         return asmJSActivationStack_;
     }
     js::Activation *activation() const {
         return activation_;
     }
     /* 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 js_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;
     // Number of active bytecode compilation on this thread.
     unsigned activeCompilations;
     PerThreadData(JSRuntime *runtime);
     ~PerThreadData();
     bool init();
     bool associatedWith(const JSRuntime *rt) { return runtime_ == rt; }
     inline JSRuntime *runtimeFromMainThread();
     inline JSRuntime *runtimeIfOnOwnerThread();
     inline bool exclusiveThreadsPresent();
     inline void addActiveCompilation();
     inline void removeActiveCompilation();
     // 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)
         {
             JS_ASSERT(!pt->runtime_);
             pt->runtime_ = rt;
         }
         ~AutoEnterRuntime() {
             pt->runtime_ = nullptr;
         }
     };
     js::jit::AutoFlushICache *autoFlushICache() const;
     void setAutoFlushICache(js::jit::AutoFlushICache *afc);
 #ifdef JS_ARM_SIMULATOR
     js::jit::Simulator *simulator() const;
     void setSimulator(js::jit::Simulator *sim);
     js::jit::SimulatorRuntime *simulatorRuntime() const;
     uintptr_t *addressOfSimulatorStackLimit();
 #endif
 };
 namespace gc {
 class MarkingValidator;
 } // namespace gc
 typedef Vector<JS::Zone *, 4, SystemAllocPolicy> ZoneVector;
 class AutoLockForExclusiveAccess;
 void RecomputeStackLimit(JSRuntime *rt, StackKind kind);
 } // 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 non-null, another runtime guaranteed to outlive this one and whose
      * permanent data may be used by this one where possible.
      */
     JSRuntime *parentRuntime;
     /*
      * If true, we've been asked to call the interrupt callback as soon as
      * possible.
      */
     mozilla::Atomic<bool, mozilla::Relaxed> interrupt;
 #if defined(JS_THREADSAFE) && defined(JS_ION)
     /*
      * If non-zero, ForkJoin should service an interrupt. This is a separate
      * flag from |interrupt| because we cannot use the mprotect trick with PJS
      * code and ignore the TriggerCallbackAnyThreadDontStopIon trigger.
      */
     mozilla::Atomic<bool, mozilla::Relaxed> interruptPar;
 #endif
     /* Set when handling a signal for a thread associated with this runtime. */
     bool handlingSignal;
     JSInterruptCallback interruptCallback;
 #ifdef DEBUG
     void assertCanLock(js::RuntimeLock which);
 #else
     void assertCanLock(js::RuntimeLock which) {}
 #endif
   private:
     /*
      * Lock taken when triggering an interrupt from another thread.
      * Protects all data that is touched in this process.
      */
 #ifdef JS_THREADSAFE
     PRLock *interruptLock;
     PRThread *interruptLockOwner;
 #else
     bool interruptLockTaken;
 #endif // JS_THREADSAFE
   public:
     class AutoLockForInterrupt {
         JSRuntime *rt;
       public:
         AutoLockForInterrupt(JSRuntime *rt MOZ_GUARD_OBJECT_NOTIFIER_PARAM) : rt(rt) {
             MOZ_GUARD_OBJECT_NOTIFIER_INIT;
             rt->assertCanLock(js::InterruptLock);
 #ifdef JS_THREADSAFE
             PR_Lock(rt->interruptLock);
             rt->interruptLockOwner = PR_GetCurrentThread();
 #else
             rt->interruptLockTaken = true;
 #endif // JS_THREADSAFE
         }
         ~AutoLockForInterrupt() {
             JS_ASSERT(rt->currentThreadOwnsInterruptLock());
 #ifdef JS_THREADSAFE
             rt->interruptLockOwner = nullptr;
             PR_Unlock(rt->interruptLock);
 #else
             rt->interruptLockTaken = false;
 #endif // JS_THREADSAFE
         }
         MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
     };
     bool currentThreadOwnsInterruptLock() {
 #if defined(JS_THREADSAFE)
         return interruptLockOwner == PR_GetCurrentThread();
 #else
         return interruptLockTaken;
 #endif
     }
 #ifdef JS_THREADSAFE
   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.
      */
     PRLock *exclusiveAccessLock;
     mozilla::DebugOnly<PRThread *> exclusiveAccessOwner;
     mozilla::DebugOnly<bool> mainThreadHasExclusiveAccess;
     /* 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);
 #endif // JS_THREADSAFE
 #ifdef DEBUG
     bool currentThreadHasExclusiveAccess() {
 #ifdef JS_THREADSAFE
         return (!numExclusiveThreads && mainThreadHasExclusiveAccess) ||
                exclusiveAccessOwner == PR_GetCurrentThread();
 #else
         return true;
 #endif
     }
 #endif // DEBUG
     bool exclusiveThreadsPresent() const {
 #ifdef JS_THREADSAFE
         return numExclusiveThreads > 0;
 #else
         return false;
 #endif
     }
     /* Embedders can use this zone however they wish. */
     JS::Zone            *systemZone;
     /* List of compartments and zones (protected by the GC lock). */
     js::ZoneVector      zones;
     /* How many compartments there are across all zones. */
     size_t              numCompartments;
     /* Locale-specific callbacks for string conversion. */
     JSLocaleCallbacks *localeCallbacks;
     /* Default locale for Internationalization API */
     char *defaultLocale;
     /* Default JSVersion. */
     JSVersion defaultVersion_;
 #ifdef JS_THREADSAFE
   private:
     /* See comment for JS_AbortIfWrongThread in jsapi.h. */
     void *ownerThread_;
     friend bool js::CurrentThreadCanAccessRuntime(JSRuntime *rt);
   public:
 #endif
     /* Temporary arena pool used while compiling and decompiling. */
     static const size_t TEMP_LIFO_ALLOC_PRIMARY_CHUNK_SIZE = 4 * 1024;
     js::LifoAlloc tempLifoAlloc;
     /*
      * Free LIFO blocks are transferred to this allocator before being freed on
      * the background GC thread.
      */
     js::LifoAlloc freeLifoAlloc;
   private:
     /*
      * Both of these allocators are used for regular expression code which is shared at the
      * thread-data level.
      */
     JSC::ExecutableAllocator *execAlloc_;
     WTF::BumpPointerAllocator *bumpAlloc_;
     js::jit::JitRuntime *jitRuntime_;
     /*
      * Self-hosting state cloned on demand into other compartments. Shared with the parent
      * runtime if there is one.
      */
     JSObject *selfHostingGlobal_;
     /* Space for interpreter frames. */
     js::InterpreterStack interpreterStack_;
     JSC::ExecutableAllocator *createExecutableAllocator(JSContext *cx);
     WTF::BumpPointerAllocator *createBumpPointerAllocator(JSContext *cx);
     js::jit::JitRuntime *createJitRuntime(JSContext *cx);
   public:
     JSC::ExecutableAllocator *getExecAlloc(JSContext *cx) {
         return execAlloc_ ? execAlloc_ : createExecutableAllocator(cx);
     }
     JSC::ExecutableAllocator &execAlloc() {
         JS_ASSERT(execAlloc_);
         return *execAlloc_;
     }
     JSC::ExecutableAllocator *maybeExecAlloc() {
         return execAlloc_;
     }
     WTF::BumpPointerAllocator *getBumpPointerAllocator(JSContext *cx) {
         return bumpAlloc_ ? bumpAlloc_ : createBumpPointerAllocator(cx);
     }
     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_;
     }
     //-------------------------------------------------------------------------
     // Self-hosting support
     //-------------------------------------------------------------------------
     bool initSelfHosting(JSContext *cx);
     void finishSelfHosting();
     void markSelfHostingGlobal(JSTracer *trc);
     bool isSelfHostingGlobal(JSObject *global) {
         return global == selfHostingGlobal_;
     }
     bool isSelfHostingCompartment(JSCompartment *comp);
     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);
     //-------------------------------------------------------------------------
     // 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();
     JSVersion defaultVersion() { return defaultVersion_; }
     void setDefaultVersion(JSVersion v) { defaultVersion_ = v; }
     /* Base address of the native stack for the current thread. */
     uintptr_t           nativeStackBase;
     /* The native stack size limit that runtime should not exceed. */
     size_t              nativeStackQuota[js::StackKindCount];
     /* Context create/destroy callback. */
     JSContextCallback   cxCallback;
     void               *cxCallbackData;
     /* Compartment destroy callback. */
     JSDestroyCompartmentCallback destroyCompartmentCallback;
     /* 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);
 #ifdef JS_THREADSAFE
     /* The request depth for this thread. */
     unsigned            requestDepth;
 # ifdef DEBUG
     unsigned            checkRequestDepth;
 # endif
 #endif
 #ifdef DEBUG
     /*
      * To help embedders enforce their invariants, we allow them to specify in
      * advance which JSContext should be passed to JSAPI calls. If this is set
      * to a non-null value, the assertSameCompartment machinery does double-
      * duty (in debug builds) to verify that it matches the cx being used.
      */
     JSContext          *activeContext;
 #endif
     /* Garbage collector state, used by jsgc.c. */
     /* Garbase collector state has been sucessfully initialized. */
     bool                gcInitialized;
     /*
      * Set of all GC chunks with at least one allocated thing. The
      * conservative GC uses it to quickly check if a possible GC thing points
      * into an allocated chunk.
      */
     js::GCChunkSet      gcChunkSet;
     /*
      * Doubly-linked lists of chunks from user and system compartments. The GC
      * allocates its arenas from the corresponding list and when all arenas
      * in the list head are taken, then the chunk is removed from the list.
      * During the GC when all arenas in a chunk become free, that chunk is
      * removed from the list and scheduled for release.
      */
     js::gc::Chunk       *gcSystemAvailableChunkListHead;
     js::gc::Chunk       *gcUserAvailableChunkListHead;
     js::gc::ChunkPool   gcChunkPool;
     js::RootedValueMap  gcRootsHash;
     /* This is updated by both the main and GC helper threads. */
     mozilla::Atomic<size_t, mozilla::ReleaseAcquire> gcBytes;
     size_t              gcMaxBytes;
     size_t              gcMaxMallocBytes;
     /*
      * Number of the committed arenas in all GC chunks including empty chunks.
      */
     mozilla::Atomic<uint32_t, mozilla::ReleaseAcquire> gcNumArenasFreeCommitted;
     js::GCMarker        gcMarker;
     void                *gcVerifyPreData;
     void                *gcVerifyPostData;
     bool                gcChunkAllocationSinceLastGC;
     int64_t             gcNextFullGCTime;
     int64_t             gcLastGCTime;
     int64_t             gcJitReleaseTime;
   private:
     JSGCMode            gcMode_;
   public:
     JSGCMode gcMode() const { return gcMode_; }
     void setGCMode(JSGCMode mode) {
         gcMode_ = mode;
         gcMarker.setGCMode(mode);
     }
     size_t              gcAllocationThreshold;
     bool                gcHighFrequencyGC;
     uint64_t            gcHighFrequencyTimeThreshold;
     uint64_t            gcHighFrequencyLowLimitBytes;
     uint64_t            gcHighFrequencyHighLimitBytes;
     double              gcHighFrequencyHeapGrowthMax;
     double              gcHighFrequencyHeapGrowthMin;
     double              gcLowFrequencyHeapGrowth;
     bool                gcDynamicHeapGrowth;
     bool                gcDynamicMarkSlice;
     uint64_t            gcDecommitThreshold;
     /* During shutdown, the GC needs to clean up every possible object. */
     bool                gcShouldCleanUpEverything;
     /*
      * The gray bits can become invalid if UnmarkGray overflows the stack. A
      * full GC will reset this bit, since it fills in all the gray bits.
      */
     bool                gcGrayBitsValid;
     /*
      * These flags must be kept separate so that a thread requesting a
      * compartment GC doesn't cancel another thread's concurrent request for a
      * full GC.
      */
     volatile uintptr_t  gcIsNeeded;
     js::gcstats::Statistics gcStats;
     /* Incremented on every GC slice. */
     uint64_t            gcNumber;
     /* The gcNumber at the time of the most recent GC's first slice. */
     uint64_t            gcStartNumber;
     /* Whether the currently running GC can finish in multiple slices. */
     bool                gcIsIncremental;
     /* Whether all compartments are being collected in first GC slice. */
     bool                gcIsFull;
     /* The reason that an interrupt-triggered GC should be called. */
     JS::gcreason::Reason gcTriggerReason;
     /*
      * If this is true, all marked objects must belong to a compartment being
      * GCed. This is used to look for compartment bugs.
      */
     bool                gcStrictCompartmentChecking;
 #ifdef DEBUG
     /*
      * 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.
      */
     uintptr_t           gcDisableStrictProxyCheckingCount;
 #else
     uintptr_t           unused1;
 #endif
     /*
      * The current incremental GC phase. This is also used internally in
      * non-incremental GC.
      */
     js::gc::State       gcIncrementalState;
     /* Indicates that the last incremental slice exhausted the mark stack. */
     bool                gcLastMarkSlice;
     /* Whether any sweeping will take place in the separate GC helper thread. */
     bool                gcSweepOnBackgroundThread;
     /* Whether any black->gray edges were found during marking. */
     bool                gcFoundBlackGrayEdges;
     /* List head of zones to be swept in the background. */
     JS::Zone            *gcSweepingZones;
     /* Index of current zone group (for stats). */
     unsigned            gcZoneGroupIndex;
     /*
      * Incremental sweep state.
      */
     JS::Zone            *gcZoneGroups;
     JS::Zone            *gcCurrentZoneGroup;
     int                 gcSweepPhase;
     JS::Zone            *gcSweepZone;
     int                 gcSweepKindIndex;
     bool                gcAbortSweepAfterCurrentGroup;
     /*
      * List head of arenas allocated during the sweep phase.
      */
     js::gc::ArenaHeader *gcArenasAllocatedDuringSweep;
 #ifdef DEBUG
     js::gc::MarkingValidator *gcMarkingValidator;
 #endif
     /*
      * Indicates that a GC slice has taken place in the middle of an animation
      * frame, rather than at the beginning. In this case, the next slice will be
      * delayed so that we don't get back-to-back slices.
      */
     volatile uintptr_t  gcInterFrameGC;
     /* Default budget for incremental GC slice. See SliceBudget in jsgc.h. */
     int64_t             gcSliceBudget;
     /*
      * We disable incremental GC if we encounter a js::Class with a trace hook
      * that does not implement write barriers.
      */
     bool                gcIncrementalEnabled;
     /*
      * GGC can be enabled from the command line while testing.
      */
     unsigned            gcGenerationalDisabled;
     /*
      * This is true if we are in the middle of a brain transplant (e.g.,
      * JS_TransplantObject) or some other operation that can manipulate
      * dead zones.
      */
     bool                gcManipulatingDeadZones;
     /*
      * This field is incremented each time we mark an object inside a
      * zone with no incoming cross-compartment pointers. Typically if
      * this happens it signals that an incremental GC is marking too much
      * stuff. At various times we check this counter and, if it has changed, we
      * run an immediate, non-incremental GC to clean up the dead
      * zones. This should happen very rarely.
      */
     unsigned            gcObjectsMarkedInDeadZones;
     bool                gcPoke;
     volatile js::HeapState heapState;
     bool isHeapBusy() { return heapState != js::Idle; }
     bool isHeapMajorCollecting() { return heapState == js::MajorCollecting; }
     bool isHeapMinorCollecting() { return heapState == js::MinorCollecting; }
     bool isHeapCollecting() { return isHeapMajorCollecting() || isHeapMinorCollecting(); }
 #ifdef JSGC_GENERATIONAL
     js::Nursery                  gcNursery;
     js::gc::StoreBuffer          gcStoreBuffer;
 #endif
     /*
      * These options control the zealousness of the GC. The fundamental values
      * are gcNextScheduled and gcDebugCompartmentGC. At every allocation,
      * gcNextScheduled is decremented. When it reaches zero, we do either a
      * full or a compartmental GC, based on gcDebugCompartmentGC.
      *
      * At this point, if gcZeal_ is one of the types that trigger periodic
      * collection, then gcNextScheduled is reset to the value of
      * gcZealFrequency. Otherwise, no additional GCs take place.
      *
      * You can control these values in several ways:
      *   - Pass the -Z flag to the shell (see the usage info for details)
      *   - Call gczeal() or schedulegc() from inside shell-executed JS code
      *     (see the help for details)
      *
      * If gzZeal_ == 1 then we perform GCs in select places (during MaybeGC and
      * whenever a GC poke happens). This option is mainly useful to embedders.
      *
      * We use gcZeal_ == 4 to enable write barrier verification. See the comment
      * in jsgc.cpp for more information about this.
      *
      * gcZeal_ values from 8 to 10 periodically run different types of
      * incremental GC.
      */
 #ifdef JS_GC_ZEAL
     int                 gcZeal_;
     int                 gcZealFrequency;
     int                 gcNextScheduled;
     bool                gcDeterministicOnly;
     int                 gcIncrementalLimit;
     js::Vector<JSObject *, 0, js::SystemAllocPolicy> gcSelectedForMarking;
     int gcZeal() { return gcZeal_; }
     bool upcomingZealousGC() {
         return gcNextScheduled == 1;
     }
     bool needZealousGC() {
         if (gcNextScheduled > 0 && --gcNextScheduled == 0) {
             if (gcZeal() == js::gc::ZealAllocValue ||
                 gcZeal() == js::gc::ZealGenerationalGCValue ||
                 (gcZeal() >= js::gc::ZealIncrementalRootsThenFinish &&
                  gcZeal() <= js::gc::ZealIncrementalMultipleSlices))
             {
                 gcNextScheduled = gcZealFrequency;
             }
             return true;
         }
         return false;
     }
 #else
     int gcZeal() { return 0; }
     bool upcomingZealousGC() { return false; }
     bool needZealousGC() { return false; }
 #endif
     bool                gcValidate;
     bool                gcFullCompartmentChecks;
     JSGCCallback        gcCallback;
     JS::GCSliceCallback gcSliceCallback;
     JSFinalizeCallback  gcFinalizeCallback;
     void                *gcCallbackData;
   private:
     /*
      * Malloc counter to measure memory pressure for GC scheduling. It runs
      * from gcMaxMallocBytes down to zero.
      */
     mozilla::Atomic<ptrdiff_t, mozilla::ReleaseAcquire> gcMallocBytes;
     /*
      * Whether a GC has been triggered as a result of gcMallocBytes falling
      * below zero.
      */
     mozilla::Atomic<bool, mozilla::ReleaseAcquire> gcMallocGCTriggered;
 #ifdef JS_ARM_SIMULATOR
     js::jit::SimulatorRuntime *simulatorRuntime_;
 #endif
   public:
     void setNeedsBarrier(bool needs) {
         needsBarrier_ = needs;
     }
     struct ExtraTracer {
         JSTraceDataOp op;
         void *data;
         ExtraTracer()
           : op(nullptr), data(nullptr)
         {}
         ExtraTracer(JSTraceDataOp op, void *data)
           : op(op), data(data)
         {}
     };
 #ifdef JS_ARM_SIMULATOR
     js::jit::SimulatorRuntime *simulatorRuntime() const;
     void setSimulatorRuntime(js::jit::SimulatorRuntime *srt);
 #endif
     /*
      * The trace operations to trace embedding-specific GC roots. One is for
      * tracing through black roots and the other is for tracing through gray
      * roots. The black/gray distinction is only relevant to the cycle
      * collector.
      */
     typedef js::Vector<ExtraTracer, 4, js::SystemAllocPolicy> ExtraTracerVector;
     ExtraTracerVector   gcBlackRootTracers;
     ExtraTracer         gcGrayRootTracer;
     /*
      * The GC can only safely decommit memory when the page size of the
      * running process matches the compiled arena size.
      */
     size_t              gcSystemPageSize;
     /* The OS allocation granularity may not match the page size. */
     size_t              gcSystemAllocGranularity;
     /* Strong references on scripts held for PCCount profiling API. */
     js::ScriptAndCountsVector *scriptAndCountsVector;
     /* Well-known numbers held for use by this runtime's contexts. */
     const js::Value     NaNValue;
     const js::Value     negativeInfinityValue;
     const js::Value     positiveInfinityValue;
     js::PropertyName    *emptyString;
     /* List of active contexts sharing this runtime. */
     mozilla::LinkedList<JSContext> contextList;
     bool hasContexts() const {
         return !contextList.isEmpty();
     }
     mozilla::ScopedDeletePtr<js::SourceHook> sourceHook;
     /* Per runtime debug hooks -- see js/OldDebugAPI.h. */
     JSDebugHooks        debugHooks;
     /* If true, new compartments are initially in debug mode. */
     bool                debugMode;
     /* SPS profiling metadata */
     js::SPSProfiler     spsProfiler;
     /* If true, new scripts must be created with PC counter information. */
     bool                profilingScripts;
     /* Always preserve JIT code during GCs, for testing. */
     bool                alwaysPreserveCode;
     /* Had an out-of-memory error which did not populate an exception. */
     bool                hadOutOfMemory;
     /* A context has been created on this runtime. */
     bool                haveCreatedContext;
     /* 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;
     /* Client opaque pointers */
     void                *data;
   private:
     /* Synchronize GC heap access between main thread and GCHelperThread. */
     PRLock *gcLock;
     mozilla::DebugOnly<PRThread *> gcLockOwner;
     friend class js::GCHelperThread;
   public:
     void lockGC() {
 #ifdef JS_THREADSAFE
         assertCanLock(js::GCLock);
         PR_Lock(gcLock);
         JS_ASSERT(!gcLockOwner);
 #ifdef DEBUG
         gcLockOwner = PR_GetCurrentThread();
 #endif
 #endif
     }
     void unlockGC() {
 #ifdef JS_THREADSAFE
         JS_ASSERT(gcLockOwner == PR_GetCurrentThread());
         gcLockOwner = nullptr;
         PR_Unlock(gcLock);
 #endif
     }
     js::GCHelperThread  gcHelperThread;
 #if defined(XP_MACOSX) && defined(JS_ION)
     js::AsmJSMachExceptionHandler asmJSMachExceptionHandler;
 #endif
     // Whether asm.js signal handlers have been installed and can be used for
     // performing interrupt checks in loops.
   private:
     bool signalHandlersInstalled_;
   public:
     bool signalHandlersInstalled() const {
         return signalHandlersInstalled_;
     }
   private:
     js::FreeOp          defaultFreeOp_;
   public:
     js::FreeOp *defaultFreeOp() {
         return &defaultFreeOp_;
     }
     uint32_t            debuggerMutations;
     const JSSecurityCallbacks *securityCallbacks;
     const js::DOMCallbacks *DOMcallbacks;
     JSDestroyPrincipalsOp destroyPrincipals;
     /* Structured data callbacks are runtime-wide. */
     const JSStructuredCloneCallbacks *structuredCloneCallbacks;
     /* Call this to accumulate telemetry data. */
     JSAccumulateTelemetryDataCallback telemetryCallback;
     /* 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:
     js::MathCache *mathCache_;
     js::MathCache *createMathCache(JSContext *cx);
   public:
     js::MathCache *getMathCache(JSContext *cx) {
         return mathCache_ ? mathCache_ : createMathCache(cx);
     }
     js::MathCache *maybeGetMathCache() {
         return mathCache_;
     }
     js::GSNCache        gsnCache;
     js::ScopeCoordinateNameCache scopeCoordinateNameCache;
     js::NewObjectCache  newObjectCache;
     js::NativeIterCache nativeIterCache;
     js::SourceDataCache sourceDataCache;
     js::EvalCache       evalCache;
     js::LazyScriptCache lazyScriptCache;
     js::DateTimeInfo    dateTimeInfo;
     js::ConservativeGCData conservativeGC;
     // Pool of maps used during parse/emit. This may be modified by threads
     // with an ExclusiveContext and requires a lock. Active compilations
     // prevent the pool from being purged during GCs.
   private:
     js::frontend::ParseMapPool parseMapPool_;
     unsigned activeCompilations_;
   public:
     js::frontend::ParseMapPool &parseMapPool() {
         JS_ASSERT(currentThreadHasExclusiveAccess());
         return parseMapPool_;
     }
     bool hasActiveCompilations() {
         return activeCompilations_ != 0;
     }
     void addActiveCompilation() {
         JS_ASSERT(currentThreadHasExclusiveAccess());
         activeCompilations_++;
     }
     void removeActiveCompilation() {
         JS_ASSERT(currentThreadHasExclusiveAccess());
         activeCompilations_--;
     }
     // 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() {
         JS_ASSERT(CurrentThreadCanAccessRuntime(this));
         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.
     // This may be modified by threads with an ExclusiveContext and requires
     // a lock.
     js::AtomSet *atoms_;
     // Compartment and associated zone containing all atoms in the runtime,
     // as well as runtime wide IonCode stubs. The contents of this compartment
     // may be modified by threads with an ExclusiveContext and requires a lock.
     JSCompartment *atomsCompartment_;
   public:
     bool initializeAtoms(JSContext *cx);
     void finishAtoms();
     void sweepAtoms();
     js::AtomSet &atoms() {
         JS_ASSERT(currentThreadHasExclusiveAccess());
         return *atoms_;
     }
     JSCompartment *atomsCompartment() {
         JS_ASSERT(currentThreadHasExclusiveAccess());
         return atomsCompartment_;
     }
     bool isAtomsCompartment(JSCompartment *comp) {
         return comp == atomsCompartment_;
     }
     // The atoms compartment is the only one in its zone.
     inline bool isAtomsZone(JS::Zone *zone);
     bool activeGCInAtomsZone();
     // 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.
     js::AtomSet *permanentAtoms;
     bool transformToPermanentAtoms();
     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_ASSERT(currentThreadHasExclusiveAccess());
         return scriptDataTable_;
     }
 #ifdef DEBUG
     size_t              noGCOrAllocationCheck;
 #endif
     bool                jitSupportsFloatingPoint;
     // Used to reset stack limit after a signaled interrupt (i.e. jitStackLimit_ = -1)
     // has been noticed by Ion/Baseline.
     void resetJitStackLimit();
     // Cache for jit::GetPcScript().
     js::jit::PcScriptCache *ionPcScriptCache;
     js::ThreadPool threadPool;
     js::DefaultJSContextCallback defaultJSContextCallback;
     js::CTypesActivityCallback  ctypesActivityCallback;
     // Non-zero if this is a ForkJoin warmup execution.  See
     // js::ForkJoin() for more information.
     uint32_t forkJoinWarmup;
   private:
     // In certain cases, we want to optimize certain opcodes to typed instructions,
     // to avoid carrying an extra register to feed into an unbox. Unfortunately,
     // that's not always possible. For example, a GetPropertyCacheT could return a
     // typed double, but if it takes its out-of-line path, it could return an
     // object, and trigger invalidation. The invalidation bailout will consider the
     // return value to be a double, and create a garbage Value.
     //
     // To allow the GetPropertyCacheT optimization, we allow the ability for
     // GetPropertyCache to override the return value at the top of the stack - the
     // value that will be temporarily corrupt. This special override value is set
     // only in callVM() targets that are about to return *and* have invalidated
     // their callee.
     js::Value            ionReturnOverride_;
 #ifdef JS_THREADSAFE
     static mozilla::Atomic<size_t> liveRuntimesCount;
 #else
     static size_t liveRuntimesCount;
 #endif
   public:
     static bool hasLiveRuntimes() {
         return liveRuntimesCount > 0;
     }
     bool hasIonReturnOverride() const {
         return !ionReturnOverride_.isMagic();
     }
     js::Value takeIonReturnOverride() {
         js::Value v = ionReturnOverride_;
         ionReturnOverride_ = js::MagicValue(JS_ARG_POISON);
         return v;
     }
     void setIonReturnOverride(const js::Value &v) {
         JS_ASSERT(!hasIonReturnOverride());
         ionReturnOverride_ = v;
     }
     JSRuntime(JSRuntime *parentRuntime, JSUseHelperThreads useHelperThreads);
     ~JSRuntime();
     bool init(uint32_t maxbytes);
     JSRuntime *thisFromCtor() { return this; }
     void setGCMaxMallocBytes(size_t value);
     void resetGCMallocBytes() {
         gcMallocBytes = ptrdiff_t(gcMaxMallocBytes);
         gcMallocGCTriggered = false;
     }
     /*
      * 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); }
     bool isTooMuchMalloc() const {
         return gcMallocBytes <= 0;
     }
     /*
      * The function must be called outside the GC lock.
      */
     JS_FRIEND_API(void) onTooMuchMalloc();
     /*
      * This should be called after system malloc/realloc returns nullptr to try
      * to recove some memory or to report an error. Failures in malloc and
      * calloc are signaled by p == null and p == reinterpret_cast<void *>(1).
      * Other values of p mean a realloc failure.
      *
      * The function must be called outside the GC lock.
      */
     JS_FRIEND_API(void *) onOutOfMemory(void *p, size_t nbytes);
     JS_FRIEND_API(void *) onOutOfMemory(void *p, size_t nbytes, JSContext *cx);
     // Ways in which the interrupt callback on the runtime can be triggered,
     // varying based on which thread is triggering the callback.
     enum InterruptMode {
         RequestInterruptMainThread,
         RequestInterruptAnyThread,
         RequestInterruptAnyThreadDontStopIon,
         RequestInterruptAnyThreadForkJoin
     };
     void requestInterrupt(InterruptMode mode);
     void addSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf, JS::RuntimeSizes *runtime);
   private:
     JS::RuntimeOptions options_;
     JSUseHelperThreads useHelperThreads_;
     // Settings for how helper threads can be used.
     bool parallelIonCompilationEnabled_;
     bool parallelParsingEnabled_;
     // True iff this is a DOM Worker runtime.
     bool isWorkerRuntime_;
   public:
     // This controls whether the JSRuntime is allowed to create any helper
     // threads at all. This means both specific threads (background GC thread)
     // and the general JS worker thread pool.
     bool useHelperThreads() const {
 #ifdef JS_THREADSAFE
         return useHelperThreads_ == JS_USE_HELPER_THREADS;
 #else
         return false;
 #endif
     }
     // Note: these values may be toggled dynamically (in response to about:config
     // prefs changing).
     void setParallelIonCompilationEnabled(bool value) {
         parallelIonCompilationEnabled_ = value;
     }
     bool canUseParallelIonCompilation() const {
         return useHelperThreads() &&
                parallelIonCompilationEnabled_;
     }
     void setParallelParsingEnabled(bool value) {
         parallelParsingEnabled_ = value;
     }
     bool canUseParallelParsing() const {
         return useHelperThreads() &&
                parallelParsingEnabled_;
     }
     void setIsWorkerRuntime() {
         isWorkerRuntime_ = true;
     }
     bool isWorkerRuntime() const {
         return isWorkerRuntime_;
     }
     const JS::RuntimeOptions &options() const {
         return options_;
     }
     JS::RuntimeOptions &options() {
         return options_;
     }
 #ifdef DEBUG
   public:
     js::AutoEnterPolicy *enteredPolicy;
 #endif
     /* See comment for JS::SetLargeAllocationFailureCallback in jsapi.h. */
     JS::LargeAllocationFailureCallback largeAllocationFailureCallback;
     /* See comment for JS::SetOutOfMemoryCallback in jsapi.h. */
     JS::OutOfMemoryCallback oomCallback;
     /*
      * 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;
     void *callocCanGC(size_t bytes) {
         void *p = calloc_(bytes);
         if (MOZ_LIKELY(!!p))
             return p;
         if (!largeAllocationFailureCallback || bytes < LARGE_ALLOCATION)
             return nullptr;
         largeAllocationFailureCallback();
         return onOutOfMemory(reinterpret_cast<void *>(1), bytes);
     }
     void *reallocCanGC(void *p, size_t bytes) {
         void *p2 = realloc_(p, bytes);
         if (MOZ_LIKELY(!!p2))
             return p2;
         if (!largeAllocationFailureCallback || bytes < LARGE_ALLOCATION)
             return nullptr;
         largeAllocationFailureCallback();
         return onOutOfMemory(p, bytes);
     }
 };
 namespace js {
 // When entering JIT code, the calling JSContext* is stored into the thread's
 // PerThreadData. This function retrieves the JSContext with the pre-condition
 // that the caller is JIT code or C++ called directly from JIT code. This
 // function should not be called from arbitrary locations since the JSContext
 // may be the wrong one.
 static inline JSContext *
 GetJSContextFromJitCode()
 {
     JSContext *cx = TlsPerThreadData.get()->jitJSContext;
     JS_ASSERT(cx);
     return cx;
 }
 /*
  * 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)
 {
     if (shouldFreeLater()) {
         runtime()->gcHelperThread.freeLater(p);
         return;
     }
     js_free(p);
 }
 class AutoLockGC
 {
   public:
     explicit AutoLockGC(JSRuntime *rt = nullptr
                         MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
       : runtime(rt)
     {
         MOZ_GUARD_OBJECT_NOTIFIER_INIT;
         // Avoid MSVC warning C4390 for non-threadsafe builds.
         if (rt)
             rt->lockGC();
     }
     ~AutoLockGC()
     {
         if (runtime)
             runtime->unlockGC();
     }
     bool locked() const {
         return !!runtime;
     }
     void lock(JSRuntime *rt) {
         JS_ASSERT(rt);
         JS_ASSERT(!runtime);
         runtime = rt;
         rt->lockGC();
     }
   private:
     JSRuntime *runtime;
     MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
 };
 class AutoUnlockGC
 {
   private:
     JSRuntime *rt;
     MOZ_DECL_USE_GUARD_OBJECT_NOTIFIER
   public:
     explicit AutoUnlockGC(JSRuntime *rt
                           MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
       : rt(rt)
     {
         MOZ_GUARD_OBJECT_NOTIFIER_INIT;
         rt->unlockGC();
     }
     ~AutoUnlockGC() { rt->lockGC(); }
 };
 class MOZ_STACK_CLASS 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.
             JS_ASSERT(pt->exclusiveThreadsPresent());
         }
     }
     ~AutoKeepAtoms() {
         if (JSRuntime *rt = pt->runtimeIfOnOwnerThread()) {
             JS_ASSERT(rt->keepAtoms_);
             rt->keepAtoms_--;
         }
     }
 };
 inline void
 PerThreadData::setJitStackLimit(uintptr_t limit)
 {
     JS_ASSERT(runtime_->currentThreadOwnsInterruptLock());
     jitStackLimit = limit;
 }
 inline JSRuntime *
 PerThreadData::runtimeFromMainThread()
 {
     JS_ASSERT(CurrentThreadCanAccessRuntime(runtime_));
     return runtime_;
 }
 inline JSRuntime *
 PerThreadData::runtimeIfOnOwnerThread()
 {
     return CurrentThreadCanAccessRuntime(runtime_) ? runtime_ : nullptr;
 }
 inline bool
 PerThreadData::exclusiveThreadsPresent()
 {
     return runtime_->exclusiveThreadsPresent();
 }
 inline void
 PerThreadData::addActiveCompilation()
 {
     activeCompilations++;
     runtime_->addActiveCompilation();
 }
 inline void
 PerThreadData::removeActiveCompilation()
 {
     JS_ASSERT(activeCompilations);
     activeCompilations--;
     runtime_->removeActiveCompilation();
 }
 /************************************************************************/
 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::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:
     RuntimeAllocPolicy(JSRuntime *rt) : runtime(rt) {}
     void *malloc_(size_t bytes) { return runtime->malloc_(bytes); }
     void *calloc_(size_t bytes) { return runtime->calloc_(bytes); }
     void *realloc_(void *p, size_t bytes) { return runtime->realloc_(p, bytes); }
     void free_(void *p) { js_free(p); }
     void reportAllocOverflow() const {}
 };
 extern const JSSecurityCallbacks NullSecurityCallbacks;
 } /* namespace js */
 #ifdef _MSC_VER
 #pragma warning(pop)
 #endif
 #endif /* vm_Runtime_h */

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js/src/vm/Runtime.h