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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef vm_Realm_h
+#define vm_Realm_h
+
+#include "mozilla/Array.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/Variant.h"
+#include "mozilla/XorShift128PlusRNG.h"
+
+#include <stddef.h>
+
+#include "builtin/Array.h"
+#include "gc/Barrier.h"
+#include "js/GCVariant.h"
+#include "js/RealmOptions.h"
+#include "js/TelemetryTimers.h"
+#include "js/UniquePtr.h"
+#include "vm/ArrayBufferObject.h"
+#include "vm/JSContext.h"
+#include "vm/PromiseLookup.h" // js::PromiseLookup
+#include "vm/RegExpShared.h"
+#include "vm/SavedStacks.h"
+#include "wasm/WasmRealm.h"
+
+namespace js {
+
+namespace coverage {
+class LCovRealm;
+} // namespace coverage
+
+namespace jit {
+class JitRealm;
+} // namespace jit
+
+class AutoRestoreRealmDebugMode;
+class Debugger;
+class GlobalObject;
+class GlobalObjectData;
+class GlobalLexicalEnvironmentObject;
+class NonSyntacticLexicalEnvironmentObject;
+struct IdValuePair;
+struct NativeIterator;
+
+/*
+ * A single-entry cache for some base-10 double-to-string conversions. This
+ * helps date-format-xparb.js. It also avoids skewing the results for
+ * v8-splay.js when measured by the SunSpider harness, where the splay tree
+ * initialization (which includes many repeated double-to-string conversions)
+ * is erroneously included in the measurement; see bug 562553.
+ */
+class DtoaCache {
+ double dbl;
+ int base;
+ JSLinearString* str; // if str==nullptr, dbl and base are not valid
+
+ public:
+ DtoaCache() : str(nullptr) {}
+ void purge() { str = nullptr; }
+
+ JSLinearString* lookup(int b, double d) {
+ return str && b == base && d == dbl ? str : nullptr;
+ }
+
+ void cache(int b, double d, JSLinearString* s) {
+ base = b;
+ dbl = d;
+ str = s;
+ }
+
+#ifdef JSGC_HASH_TABLE_CHECKS
+ void checkCacheAfterMovingGC();
+#endif
+};
+
+// Cache to speed up the group/shape lookup in ProxyObject::create. A proxy's
+// shape is only determined by the Class + proto, so a small cache for this is
+// very effective in practice.
+class NewProxyCache {
+ struct Entry {
+ Shape* shape;
+ };
+ static const size_t NumEntries = 4;
+ mozilla::UniquePtr<Entry[], JS::FreePolicy> entries_;
+
+ public:
+ MOZ_ALWAYS_INLINE bool lookup(const JSClass* clasp, TaggedProto proto,
+ Shape** shape) const {
+ if (!entries_) {
+ return false;
+ }
+ for (size_t i = 0; i < NumEntries; i++) {
+ const Entry& entry = entries_[i];
+ if (entry.shape && entry.shape->getObjectClass() == clasp &&
+ entry.shape->proto() == proto) {
+ *shape = entry.shape;
+ return true;
+ }
+ }
+ return false;
+ }
+ void add(Shape* shape) {
+ MOZ_ASSERT(shape);
+ if (!entries_) {
+ entries_.reset(js_pod_calloc<Entry>(NumEntries));
+ if (!entries_) {
+ return;
+ }
+ } else {
+ for (size_t i = NumEntries - 1; i > 0; i--) {
+ entries_[i] = entries_[i - 1];
+ }
+ }
+ entries_[0].shape = shape;
+ }
+ void purge() { entries_.reset(); }
+};
+
+// Cache for NewPlainObjectWithProperties. When the list of properties matches
+// a recently created object's shape, we can use this shape directly.
+class NewPlainObjectWithPropsCache {
+ static const size_t NumEntries = 4;
+ mozilla::Array<SharedShape*, NumEntries> entries_;
+
+ public:
+ NewPlainObjectWithPropsCache() { purge(); }
+
+ SharedShape* lookup(IdValuePair* properties, size_t nproperties) const;
+ void add(SharedShape* shape);
+
+ void purge() {
+ for (size_t i = 0; i < NumEntries; i++) {
+ entries_[i] = nullptr;
+ }
+ }
+};
+
+// [SMDOC] Object MetadataBuilder API
+//
+// We must ensure that all newly allocated JSObjects get their metadata
+// set. However, metadata builders may require the new object be in a sane
+// state (eg, have its reserved slots initialized so they can get the
+// sizeOfExcludingThis of the object). Therefore, for objects of certain
+// JSClasses (those marked with JSCLASS_DELAY_METADATA_BUILDER), it is not safe
+// for the allocation paths to call the object metadata builder
+// immediately. Instead, the JSClass-specific "constructor" C++ function up the
+// stack makes a promise that it will ensure that the new object has its
+// metadata set after the object is initialized.
+//
+// The js::AutoSetNewObjectMetadata RAII class provides an ergonomic way for
+// constructor functions to do this.
+//
+// In the presence of internal errors, we do not set the new object's metadata
+// (if it was even allocated).
+
+class PropertyIteratorObject;
+
+struct IteratorHashPolicy {
+ struct Lookup {
+ Shape** shapes;
+ size_t numShapes;
+ HashNumber shapesHash;
+
+ Lookup(Shape** shapes, size_t numShapes, HashNumber shapesHash)
+ : shapes(shapes), numShapes(numShapes), shapesHash(shapesHash) {
+ MOZ_ASSERT(numShapes > 0);
+ }
+ };
+ static HashNumber hash(const Lookup& lookup) { return lookup.shapesHash; }
+ static bool match(PropertyIteratorObject* obj, const Lookup& lookup);
+};
+
+class DebugEnvironments;
+class ObjectWeakMap;
+
+// ObjectRealm stores various tables and other state associated with particular
+// objects in a realm. To make sure the correct ObjectRealm is used for an
+// object, use of the ObjectRealm::get(obj) static method is required.
+class ObjectRealm {
+ // All non-syntactic lexical environments in the realm. These are kept in a
+ // map because when loading scripts into a non-syntactic environment, we
+ // need to use the same lexical environment to persist lexical bindings.
+ js::UniquePtr<js::ObjectWeakMap> nonSyntacticLexicalEnvironments_;
+
+ ObjectRealm(const ObjectRealm&) = delete;
+ void operator=(const ObjectRealm&) = delete;
+
+ public:
+ // Map from array buffers to views sharing that storage.
+ JS::WeakCache<js::InnerViewTable> innerViews;
+
+ // Keep track of the metadata objects which can be associated with each JS
+ // object. Both keys and values are in this realm.
+ js::UniquePtr<js::ObjectWeakMap> objectMetadataTable;
+
+ using IteratorCache =
+ js::HashSet<js::PropertyIteratorObject*, js::IteratorHashPolicy,
+ js::ZoneAllocPolicy>;
+ IteratorCache iteratorCache;
+
+ static inline ObjectRealm& get(const JSObject* obj);
+
+ explicit ObjectRealm(JS::Zone* zone);
+
+ void finishRoots();
+ void trace(JSTracer* trc);
+ void sweepAfterMinorGC(JSTracer* trc);
+
+ void addSizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf,
+ size_t* innerViewsArg,
+ size_t* objectMetadataTablesArg,
+ size_t* nonSyntacticLexicalEnvironmentsArg);
+
+ js::NonSyntacticLexicalEnvironmentObject*
+ getOrCreateNonSyntacticLexicalEnvironment(JSContext* cx,
+ js::HandleObject enclosing);
+ js::NonSyntacticLexicalEnvironmentObject*
+ getOrCreateNonSyntacticLexicalEnvironment(JSContext* cx,
+ js::HandleObject enclosing,
+ js::HandleObject key,
+ js::HandleObject thisv);
+ js::NonSyntacticLexicalEnvironmentObject* getNonSyntacticLexicalEnvironment(
+ JSObject* key) const;
+};
+
+} // namespace js
+
+class JS::Realm : public JS::shadow::Realm {
+ JS::Zone* zone_;
+ JSRuntime* runtime_;
+
+ const JS::RealmCreationOptions creationOptions_;
+ JS::RealmBehaviors behaviors_;
+
+ friend struct ::JSContext;
+ js::WeakHeapPtr<js::GlobalObject*> global_;
+
+ // Note: this is private to enforce use of ObjectRealm::get(obj).
+ js::ObjectRealm objects_;
+ friend js::ObjectRealm& js::ObjectRealm::get(const JSObject*);
+
+ // See the "Object MetadataBuilder API" comment.
+ JSObject* objectPendingMetadata_ = nullptr;
+#ifdef DEBUG
+ uint32_t numActiveAutoSetNewObjectMetadata_ = 0;
+#endif
+
+ // Random number generator for Math.random().
+ mozilla::Maybe<mozilla::non_crypto::XorShift128PlusRNG>
+ randomNumberGenerator_;
+
+ // Random number generator for randomHashCodeScrambler().
+ mozilla::non_crypto::XorShift128PlusRNG randomKeyGenerator_;
+
+ JSPrincipals* principals_ = nullptr;
+
+ js::UniquePtr<js::jit::JitRealm> jitRealm_;
+
+ // Bookkeeping information for debug scope objects.
+ js::UniquePtr<js::DebugEnvironments> debugEnvs_;
+
+ js::SavedStacks savedStacks_;
+
+ // Used by memory reporters and invalid otherwise.
+ JS::RealmStats* realmStats_ = nullptr;
+
+ const js::AllocationMetadataBuilder* allocationMetadataBuilder_ = nullptr;
+ void* realmPrivate_ = nullptr;
+
+ // There are two ways to enter a realm:
+ //
+ // (1) AutoRealm (and JSAutoRealm, JS::EnterRealm)
+ // (2) When calling a cross-realm (but same-compartment) function in JIT
+ // code.
+ //
+ // This field only accounts for (1), to keep the JIT code as simple as
+ // possible.
+ //
+ // An important invariant is that the JIT can only switch to a different
+ // realm within the same compartment, so whenever that happens there must
+ // always be a same-compartment realm with enterRealmDepthIgnoringJit_ > 0.
+ // This lets us set Compartment::hasEnteredRealm without walking the
+ // stack.
+ unsigned enterRealmDepthIgnoringJit_ = 0;
+
+ public:
+ // Various timers for collecting time spent delazifying, jit compiling,
+ // executing, etc
+ JS::JSTimers timers;
+
+ struct DebuggerVectorEntry {
+ // The debugger relies on iterating through the DebuggerVector to know what
+ // debuggers to notify about certain actions, which it does using this
+ // pointer. We need an explicit Debugger* because the JSObject* from
+ // the DebuggerDebuggeeLink to the Debugger is only set some of the time.
+ // This `Debugger*` pointer itself could also live on the
+ // DebuggerDebuggeeLink itself, but that would then require all of the
+ // places that iterate over the realm's DebuggerVector to also traverse
+ // the CCW which seems like it would be needlessly complicated.
+ js::WeakHeapPtr<js::Debugger*> dbg;
+
+ // This links to the debugger's DebuggerDebuggeeLink object, via a CCW.
+ // Tracing this link from the realm allows the debugger to define
+ // whether pieces of the debugger should be held live by a given realm.
+ js::HeapPtr<JSObject*> debuggerLink;
+
+ DebuggerVectorEntry(js::Debugger* dbg_, JSObject* link);
+ };
+ using DebuggerVector =
+ js::Vector<DebuggerVectorEntry, 0, js::ZoneAllocPolicy>;
+
+ private:
+ DebuggerVector debuggers_;
+
+ enum {
+ IsDebuggee = 1 << 0,
+ DebuggerObservesAllExecution = 1 << 1,
+ DebuggerObservesAsmJS = 1 << 2,
+ DebuggerObservesCoverage = 1 << 3,
+ DebuggerObservesWasm = 1 << 4,
+ };
+ unsigned debugModeBits_ = 0;
+ friend class js::AutoRestoreRealmDebugMode;
+
+ bool isSystem_ = false;
+ bool allocatedDuringIncrementalGC_;
+ bool initializingGlobal_ = true;
+
+ js::UniquePtr<js::coverage::LCovRealm> lcovRealm_ = nullptr;
+
+ public:
+ // WebAssembly state for the realm.
+ js::wasm::Realm wasm;
+
+ js::RegExpRealm regExps;
+
+ js::DtoaCache dtoaCache;
+ js::NewProxyCache newProxyCache;
+ js::NewPlainObjectWithPropsCache newPlainObjectWithPropsCache;
+ js::ArraySpeciesLookup arraySpeciesLookup;
+ js::PromiseLookup promiseLookup;
+
+ // Last time at which an animation was played for this realm.
+ js::MainThreadData<mozilla::TimeStamp> lastAnimationTime;
+
+ /*
+ * For generational GC, record whether a write barrier has added this
+ * realm's global to the store buffer since the last minor GC.
+ *
+ * This is used to avoid calling into the VM every time a nursery object is
+ * written to a property of the global.
+ */
+ uint32_t globalWriteBarriered = 0;
+
+ // Counter for shouldCaptureStackForThrow.
+ uint16_t numStacksCapturedForThrow_ = 0;
+
+#ifdef DEBUG
+ bool firedOnNewGlobalObject = false;
+#endif
+
+ // True if all incoming wrappers have been nuked. This happens when
+ // NukeCrossCompartmentWrappers is called with the NukeAllReferences option.
+ // This prevents us from creating new wrappers for the compartment.
+ bool nukedIncomingWrappers = false;
+
+ // Enable async stack capturing for this realm even if
+ // JS::ContextOptions::asyncStackCaptureDebuggeeOnly_ is true.
+ //
+ // No-op when JS::ContextOptions::asyncStack_ is false, or
+ // JS::ContextOptions::asyncStackCaptureDebuggeeOnly_ is false.
+ //
+ // This can be used as a lightweight alternative for making the global
+ // debuggee, if the async stack capturing is necessary but no other debugging
+ // features are used.
+ bool isAsyncStackCapturingEnabled = false;
+
+ // Allow to collect more than 50 stack traces for throw even if the global is
+ // not a debuggee.
+ //
+ // Similarly to isAsyncStackCapturingEnabled, this is a lightweight
+ // alternative for making the global a debuggee, when no actual debugging
+ // features are required.
+ bool isUnlimitedStacksCapturingEnabled = false;
+
+ private:
+ void updateDebuggerObservesFlag(unsigned flag);
+
+ Realm(const Realm&) = delete;
+ void operator=(const Realm&) = delete;
+
+ public:
+ Realm(JS::Compartment* comp, const JS::RealmOptions& options);
+ ~Realm();
+
+ void init(JSContext* cx, JSPrincipals* principals);
+ void destroy(JS::GCContext* gcx);
+
+ void addSizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf,
+ size_t* realmObject, size_t* realmTables,
+ size_t* innerViewsArg,
+ size_t* objectMetadataTablesArg,
+ size_t* savedStacksSet,
+ size_t* nonSyntacticLexicalEnvironmentsArg,
+ size_t* jitRealm);
+
+ JS::Zone* zone() { return zone_; }
+ const JS::Zone* zone() const { return zone_; }
+
+ JSRuntime* runtimeFromMainThread() const {
+ MOZ_ASSERT(js::CurrentThreadCanAccessRuntime(runtime_));
+ return runtime_;
+ }
+
+ // Note: Unrestricted access to the runtime from an arbitrary thread
+ // can easily lead to races. Use this method very carefully.
+ JSRuntime* runtimeFromAnyThread() const { return runtime_; }
+
+ const JS::RealmCreationOptions& creationOptions() const {
+ return creationOptions_;
+ }
+
+ // NOTE: Do not provide accessor for mutable reference.
+ // Modifying RealmBehaviors after creating a realm can result in
+ // inconsistency.
+ const JS::RealmBehaviors& behaviors() const { return behaviors_; }
+
+ void setNonLive() { behaviors_.setNonLive(); }
+
+ /* Whether to preserve JIT code on non-shrinking GCs. */
+ bool preserveJitCode() { return creationOptions_.preserveJitCode(); }
+
+ /* The global object for this realm.
+ *
+ * Note: the global_ field is null briefly during GC, after the global
+ * object is collected; but when that happens the Realm is destroyed during
+ * the same GC.)
+ *
+ * In contrast, JSObject::global() is infallible because marking a JSObject
+ * always marks its global as well.
+ */
+ inline js::GlobalObject* maybeGlobal() const;
+
+ /* An unbarriered getter for use while tracing. */
+ js::GlobalObject* unsafeUnbarrieredMaybeGlobal() const {
+ return global_.unbarrieredGet();
+ }
+
+ /* True if a global exists and it's not being collected. */
+ inline bool hasLiveGlobal() const;
+
+ /* True if a global exists and has been successfully initialized. */
+ inline bool hasInitializedGlobal() const;
+
+ inline void initGlobal(js::GlobalObject& global);
+ void clearInitializingGlobal() { initializingGlobal_ = false; }
+
+ /*
+ * This method traces data that is live iff we know that this realm's
+ * global is still live.
+ */
+ void traceGlobalData(JSTracer* trc);
+
+ void traceWeakGlobalEdge(JSTracer* trc);
+
+ /*
+ * This method traces Realm-owned GC roots that are considered live
+ * regardless of whether the realm's global is still live.
+ */
+ void traceRoots(JSTracer* trc,
+ js::gc::GCRuntime::TraceOrMarkRuntime traceOrMark);
+ /*
+ * This method clears out tables of roots in preparation for the final GC.
+ */
+ void finishRoots();
+
+ void sweepAfterMinorGC(JSTracer* trc);
+ void traceWeakDebugEnvironmentEdges(JSTracer* trc);
+ void traceWeakRegExps(JSTracer* trc);
+
+ void clearScriptCounts();
+ void clearScriptLCov();
+
+ void purge();
+
+ void fixupAfterMovingGC(JSTracer* trc);
+
+ void enter() { enterRealmDepthIgnoringJit_++; }
+ void leave() {
+ MOZ_ASSERT(enterRealmDepthIgnoringJit_ > 0);
+ enterRealmDepthIgnoringJit_--;
+ }
+ bool hasBeenEnteredIgnoringJit() const {
+ return enterRealmDepthIgnoringJit_ > 0;
+ }
+ bool shouldTraceGlobal() const {
+ // If we entered this realm in JIT code, there must be a script and
+ // function on the stack for this realm, so the global will definitely
+ // be traced and it's safe to return false here.
+ return hasBeenEnteredIgnoringJit();
+ }
+
+ bool hasAllocationMetadataBuilder() const {
+ return allocationMetadataBuilder_;
+ }
+ const js::AllocationMetadataBuilder* getAllocationMetadataBuilder() const {
+ return allocationMetadataBuilder_;
+ }
+ const void* addressOfMetadataBuilder() const {
+ return &allocationMetadataBuilder_;
+ }
+ bool isRecordingAllocations();
+ void setAllocationMetadataBuilder(
+ const js::AllocationMetadataBuilder* builder);
+ void forgetAllocationMetadataBuilder();
+ void setNewObjectMetadata(JSContext* cx, JS::HandleObject obj);
+
+ bool hasObjectPendingMetadata() const {
+ MOZ_ASSERT_IF(objectPendingMetadata_, hasAllocationMetadataBuilder());
+ return objectPendingMetadata_ != nullptr;
+ }
+ void setObjectPendingMetadata(JSObject* obj) {
+ MOZ_ASSERT(numActiveAutoSetNewObjectMetadata_ > 0,
+ "Must not use JSCLASS_DELAY_METADATA_BUILDER without "
+ "AutoSetNewObjectMetadata");
+ MOZ_ASSERT(!objectPendingMetadata_);
+ MOZ_ASSERT(obj);
+ if (MOZ_UNLIKELY(hasAllocationMetadataBuilder())) {
+ objectPendingMetadata_ = obj;
+ }
+ }
+ JSObject* getAndClearObjectPendingMetadata() {
+ MOZ_ASSERT(hasAllocationMetadataBuilder());
+ JSObject* obj = objectPendingMetadata_;
+ objectPendingMetadata_ = nullptr;
+ return obj;
+ }
+
+#ifdef DEBUG
+ void incNumActiveAutoSetNewObjectMetadata() {
+ numActiveAutoSetNewObjectMetadata_++;
+ }
+ void decNumActiveAutoSetNewObjectMetadata() {
+ MOZ_ASSERT(numActiveAutoSetNewObjectMetadata_ > 0);
+ numActiveAutoSetNewObjectMetadata_--;
+ }
+#endif
+
+ void* realmPrivate() const { return realmPrivate_; }
+ void setRealmPrivate(void* p) { realmPrivate_ = p; }
+
+ // This should only be called when it is non-null, i.e. during memory
+ // reporting.
+ JS::RealmStats& realmStats() {
+ // We use MOZ_RELEASE_ASSERT here because in bug 1132502 there was some
+ // (inconclusive) evidence that realmStats_ can be nullptr unexpectedly.
+ MOZ_RELEASE_ASSERT(realmStats_);
+ return *realmStats_;
+ }
+ void nullRealmStats() {
+ MOZ_ASSERT(realmStats_);
+ realmStats_ = nullptr;
+ }
+ void setRealmStats(JS::RealmStats* newStats) {
+ MOZ_ASSERT(!realmStats_ && newStats);
+ realmStats_ = newStats;
+ }
+
+ inline bool marked() const;
+ void clearAllocatedDuringGC() { allocatedDuringIncrementalGC_ = false; }
+
+ /*
+ * The principals associated with this realm. Note that the same several
+ * realms may share the same principals and that a realm may change
+ * principals during its lifetime (e.g. in case of lazy parsing).
+ */
+ JSPrincipals* principals() { return principals_; }
+ void setPrincipals(JSPrincipals* principals) { principals_ = principals; }
+
+ bool isSystem() const { return isSystem_; }
+ //
+ // The Debugger observes execution on a frame-by-frame basis. The
+ // invariants of Realm's debug mode bits, JSScript::isDebuggee,
+ // InterpreterFrame::isDebuggee, and BaselineFrame::isDebuggee are
+ // enumerated below.
+ //
+ // 1. When a realm's isDebuggee() == true, relazification and lazy
+ // parsing are disabled.
+ //
+ // Whether AOT wasm is disabled is togglable by the Debugger API. By
+ // default it is disabled. See debuggerObservesAsmJS below.
+ //
+ // 2. When a realm's debuggerObservesAllExecution() == true, all of
+ // the realm's scripts are considered debuggee scripts.
+ //
+ // 3. A script is considered a debuggee script either when, per above, its
+ // realm is observing all execution, or if it has breakpoints set.
+ //
+ // 4. A debuggee script always pushes a debuggee frame.
+ //
+ // 5. A debuggee frame calls all slow path Debugger hooks in the
+ // Interpreter and Baseline. A debuggee frame implies that its script's
+ // BaselineScript, if extant, has been compiled with debug hook calls.
+ //
+ // 6. A debuggee script or a debuggee frame (i.e., during OSR) ensures
+ // that the compiled BaselineScript is compiled with debug hook calls
+ // when attempting to enter Baseline.
+ //
+ // 7. A debuggee script or a debuggee frame (i.e., during OSR) does not
+ // attempt to enter Ion.
+ //
+ // Note that a debuggee frame may exist without its script being a
+ // debuggee script. e.g., Debugger.Frame.prototype.eval only marks the
+ // frame in which it is evaluating as a debuggee frame.
+ //
+
+ // True if this realm's global is a debuggee of some Debugger
+ // object.
+ bool isDebuggee() const { return !!(debugModeBits_ & IsDebuggee); }
+
+ void setIsDebuggee();
+ void unsetIsDebuggee();
+
+ DebuggerVector& getDebuggers(const JS::AutoRequireNoGC& nogc) {
+ return debuggers_;
+ };
+ bool hasDebuggers() const { return !debuggers_.empty(); }
+
+ // True if this compartment's global is a debuggee of some Debugger
+ // object with a live hook that observes all execution; e.g.,
+ // onEnterFrame.
+ bool debuggerObservesAllExecution() const {
+ static const unsigned Mask = IsDebuggee | DebuggerObservesAllExecution;
+ return (debugModeBits_ & Mask) == Mask;
+ }
+ void updateDebuggerObservesAllExecution() {
+ updateDebuggerObservesFlag(DebuggerObservesAllExecution);
+ }
+
+ // True if this realm's global is a debuggee of some Debugger object
+ // whose allowUnobservedAsmJS flag is false.
+ bool debuggerObservesAsmJS() const {
+ static const unsigned Mask = IsDebuggee | DebuggerObservesAsmJS;
+ return (debugModeBits_ & Mask) == Mask;
+ }
+ void updateDebuggerObservesAsmJS() {
+ updateDebuggerObservesFlag(DebuggerObservesAsmJS);
+ }
+
+ // True if this realm's global is a debuggee of some Debugger object
+ // whose allowUnobservedWasm flag is false.
+ //
+ // Note that since AOT wasm functions cannot bail out, this flag really
+ // means "observe wasm from this point forward". We cannot make
+ // already-compiled wasm code observable to Debugger.
+ bool debuggerObservesWasm() const {
+ static const unsigned Mask = IsDebuggee | DebuggerObservesWasm;
+ return (debugModeBits_ & Mask) == Mask;
+ }
+ void updateDebuggerObservesWasm() {
+ updateDebuggerObservesFlag(DebuggerObservesWasm);
+ }
+
+ // True if this realm's global is a debuggee of some Debugger object
+ // whose collectCoverageInfo flag is true.
+ bool debuggerObservesCoverage() const {
+ static const unsigned Mask = DebuggerObservesCoverage;
+ return (debugModeBits_ & Mask) == Mask;
+ }
+ void updateDebuggerObservesCoverage();
+
+ // Returns true if the Debugger API is collecting code coverage data for this
+ // realm or if the process-wide LCov option is enabled.
+ bool collectCoverageForDebug() const;
+
+ // Get or allocate the associated LCovRealm.
+ js::coverage::LCovRealm* lcovRealm();
+
+ bool shouldCaptureStackForThrow();
+
+ // Initializes randomNumberGenerator if needed.
+ mozilla::non_crypto::XorShift128PlusRNG& getOrCreateRandomNumberGenerator();
+
+ const mozilla::non_crypto::XorShift128PlusRNG*
+ addressOfRandomNumberGenerator() const {
+ return randomNumberGenerator_.ptr();
+ }
+
+ mozilla::HashCodeScrambler randomHashCodeScrambler();
+
+ bool ensureJitRealmExists(JSContext* cx);
+ void traceWeakEdgesInJitRealm(JSTracer* trc);
+
+ js::jit::JitRealm* jitRealm() { return jitRealm_.get(); }
+
+ js::DebugEnvironments* debugEnvs() { return debugEnvs_.get(); }
+ js::UniquePtr<js::DebugEnvironments>& debugEnvsRef() { return debugEnvs_; }
+
+ js::SavedStacks& savedStacks() { return savedStacks_; }
+
+ // Recompute the probability with which this realm should record
+ // profiling data (stack traces, allocations log, etc.) about each
+ // allocation. We first consult the JS runtime to see if it is recording
+ // allocations, and if not then check the probabilities requested by the
+ // Debugger instances observing us, if any.
+ void chooseAllocationSamplingProbability() {
+ savedStacks_.chooseSamplingProbability(this);
+ }
+
+ void traceWeakSavedStacks(JSTracer* trc);
+
+ static constexpr size_t offsetOfCompartment() {
+ return offsetof(JS::Realm, compartment_);
+ }
+ static constexpr size_t offsetOfRegExps() {
+ return offsetof(JS::Realm, regExps);
+ }
+ static constexpr size_t offsetOfJitRealm() {
+ return offsetof(JS::Realm, jitRealm_);
+ }
+ static constexpr size_t offsetOfDebugModeBits() {
+ return offsetof(JS::Realm, debugModeBits_);
+ }
+ static constexpr uint32_t debugModeIsDebuggeeBit() { return IsDebuggee; }
+
+ // Note: similar to cx->global(), JIT code can omit the read barrier for the
+ // context's active global.
+ static constexpr size_t offsetOfActiveGlobal() {
+ static_assert(sizeof(global_) == sizeof(uintptr_t),
+ "JIT code assumes field is pointer-sized");
+ return offsetof(JS::Realm, global_);
+ }
+
+ private:
+ void purgeForOfPicChain();
+};
+
+inline js::Handle<js::GlobalObject*> JSContext::global() const {
+ /*
+ * It's safe to use |unbarrieredGet()| here because any realm that is on-stack
+ * will be marked automatically, so there's no need for a read barrier on
+ * it. Once the realm is popped, the handle is no longer safe to use.
+ */
+ MOZ_ASSERT(realm_, "Caller needs to enter a realm first");
+ return js::Handle<js::GlobalObject*>::fromMarkedLocation(
+ realm_->global_.unbarrieredAddress());
+}
+
+namespace js {
+
+class MOZ_RAII AssertRealmUnchanged {
+ public:
+ explicit AssertRealmUnchanged(JSContext* cx)
+ : cx(cx), oldRealm(cx->realm()) {}
+
+ ~AssertRealmUnchanged() { MOZ_ASSERT(cx->realm() == oldRealm); }
+
+ protected:
+ JSContext* const cx;
+ JS::Realm* const oldRealm;
+};
+
+// AutoRealm can be used to enter the realm of a JSObject, JSScript or
+// ObjectGroup. It must not be used with cross-compartment wrappers, because
+// CCWs are not associated with a single realm.
+class AutoRealm {
+ JSContext* const cx_;
+ JS::Realm* const origin_;
+
+ public:
+ template <typename T>
+ inline AutoRealm(JSContext* cx, const T& target);
+ inline ~AutoRealm();
+
+ JSContext* context() const { return cx_; }
+ JS::Realm* origin() const { return origin_; }
+
+ protected:
+ inline AutoRealm(JSContext* cx, JS::Realm* target);
+
+ private:
+ AutoRealm(const AutoRealm&) = delete;
+ AutoRealm& operator=(const AutoRealm&) = delete;
+};
+
+class MOZ_RAII AutoAllocInAtomsZone {
+ JSContext* const cx_;
+ JS::Realm* const origin_;
+ AutoAllocInAtomsZone(const AutoAllocInAtomsZone&) = delete;
+ AutoAllocInAtomsZone& operator=(const AutoAllocInAtomsZone&) = delete;
+
+ public:
+ inline explicit AutoAllocInAtomsZone(JSContext* cx);
+ inline ~AutoAllocInAtomsZone();
+};
+
+// During GC we sometimes need to enter a realm when we may have been allocating
+// in the the atoms zone. This leaves the atoms zone temporarily. This happens
+// in embedding callbacks and when we need to mark object groups as pretenured.
+class MOZ_RAII AutoMaybeLeaveAtomsZone {
+ JSContext* const cx_;
+ bool wasInAtomsZone_;
+ AutoMaybeLeaveAtomsZone(const AutoMaybeLeaveAtomsZone&) = delete;
+ AutoMaybeLeaveAtomsZone& operator=(const AutoMaybeLeaveAtomsZone&) = delete;
+
+ public:
+ inline explicit AutoMaybeLeaveAtomsZone(JSContext* cx);
+ inline ~AutoMaybeLeaveAtomsZone();
+};
+
+// Enter a realm directly. Only use this where there's no target GC thing
+// to pass to AutoRealm or where you need to avoid the assertions in
+// JS::Compartment::enterCompartmentOf().
+class AutoRealmUnchecked : protected AutoRealm {
+ public:
+ inline AutoRealmUnchecked(JSContext* cx, JS::Realm* target);
+};
+
+// Similar to AutoRealm, but this uses GetFunctionRealm in the spec, and
+// handles both bound functions and proxies.
+//
+// If GetFunctionRealm fails for the following reasons, this does nothing:
+// * `fun` is revoked proxy
+// * unwrapping failed because of a security wrapper
+class AutoFunctionOrCurrentRealm {
+ mozilla::Maybe<AutoRealmUnchecked> ar_;
+
+ public:
+ inline AutoFunctionOrCurrentRealm(JSContext* cx, js::HandleObject fun);
+ ~AutoFunctionOrCurrentRealm() = default;
+
+ private:
+ AutoFunctionOrCurrentRealm(const AutoFunctionOrCurrentRealm&) = delete;
+ AutoFunctionOrCurrentRealm& operator=(const AutoFunctionOrCurrentRealm&) =
+ delete;
+};
+
+/*
+ * Use this to change the behavior of an AutoRealm slightly on error. If
+ * the exception happens to be an Error object, copy it to the origin
+ * compartment instead of wrapping it.
+ */
+class ErrorCopier {
+ mozilla::Maybe<AutoRealm>& ar;
+
+ public:
+ explicit ErrorCopier(mozilla::Maybe<AutoRealm>& ar) : ar(ar) {}
+ ~ErrorCopier();
+};
+
+// See the "Object MetadataBuilder API" comment.
+class MOZ_RAII AutoSetNewObjectMetadata {
+ JSContext* cx_;
+
+ AutoSetNewObjectMetadata(const AutoSetNewObjectMetadata& aOther) = delete;
+ void operator=(const AutoSetNewObjectMetadata& aOther) = delete;
+
+ void setPendingMetadata();
+
+ public:
+ explicit inline AutoSetNewObjectMetadata(JSContext* cx) : cx_(cx) {
+#ifdef DEBUG
+ MOZ_ASSERT(cx->isMainThreadContext());
+ MOZ_ASSERT(!cx->realm()->hasObjectPendingMetadata());
+ cx_->realm()->incNumActiveAutoSetNewObjectMetadata();
+#endif
+ }
+ inline ~AutoSetNewObjectMetadata() {
+#ifdef DEBUG
+ cx_->realm()->decNumActiveAutoSetNewObjectMetadata();
+#endif
+ if (MOZ_UNLIKELY(cx_->realm()->hasAllocationMetadataBuilder())) {
+ setPendingMetadata();
+ }
+ }
+};
+
+} /* namespace js */
+
+#endif /* vm_Realm_h */