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 /* -*- 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/. */

 /* Definitions related to javascript type inference. */

 #ifndef jsinfer_h

 #define jsinfer_h

 #include "mozilla/MemoryReporting.h"

 #include "mozilla/TypedEnum.h"

 #include "jsalloc.h"

 #include "jsfriendapi.h"

 #include "jstypes.h"

 #include "ds/IdValuePair.h"

 #include "ds/LifoAlloc.h"

 #include "gc/Barrier.h"

 #include "gc/Marking.h"

 #include "jit/IonTypes.h"

 #include "js/Utility.h"

 #include "js/Vector.h"

 namespace js {

 class TypeDescr;

 class TaggedProto

 {

   public:

     static JSObject * const LazyProto;

     TaggedProto() : proto(nullptr) {}

     TaggedProto(JSObject *proto) : proto(proto) {}

     uintptr_t toWord() const { return uintptr_t(proto); }

     bool isLazy() const {

         return proto == LazyProto;

     }

     bool isObject() const {

         /* Skip nullptr and LazyProto. */

         return uintptr_t(proto) > uintptr_t(TaggedProto::LazyProto);

     }

     JSObject *toObject() const {

         JS_ASSERT(isObject());

         return proto;

     }

     JSObject *toObjectOrNull() const {

         JS_ASSERT(!proto || isObject());

         return proto;

     }

     JSObject *raw() const { return proto; }

     bool operator ==(const TaggedProto &other) { return proto == other.proto; }

     bool operator !=(const TaggedProto &other) { return proto != other.proto; }

   private:

     JSObject *proto;

 };

 template <>

 struct RootKind<TaggedProto>

 {

     static ThingRootKind rootKind() { return THING_ROOT_OBJECT; }

 };

 template <> struct GCMethods<const TaggedProto>

 {

     static TaggedProto initial() { return TaggedProto(); }

     static ThingRootKind kind() { return THING_ROOT_OBJECT; }

     static bool poisoned(const TaggedProto &v) { return IsPoisonedPtr(v.raw()); }

 };

 template <> struct GCMethods<TaggedProto>

 {

     static TaggedProto initial() { return TaggedProto(); }

     static ThingRootKind kind() { return THING_ROOT_OBJECT; }

     static bool poisoned(const TaggedProto &v) { return IsPoisonedPtr(v.raw()); }

 };

 template<class Outer>

 class TaggedProtoOperations

 {

     const TaggedProto *value() const {

         return static_cast<const Outer*>(this)->extract();

     }

   public:

     uintptr_t toWord() const { return value()->toWord(); }

     inline bool isLazy() const { return value()->isLazy(); }

     inline bool isObject() const { return value()->isObject(); }

     inline JSObject *toObject() const { return value()->toObject(); }

     inline JSObject *toObjectOrNull() const { return value()->toObjectOrNull(); }

     JSObject *raw() const { return value()->raw(); }

 };

 template <>

 class HandleBase<TaggedProto> : public TaggedProtoOperations<Handle<TaggedProto> >

 {

     friend class TaggedProtoOperations<Handle<TaggedProto> >;

     const TaggedProto * extract() const {

         return static_cast<const Handle<TaggedProto>*>(this)->address();

     }

 };

 template <>

 class RootedBase<TaggedProto> : public TaggedProtoOperations<Rooted<TaggedProto> >

 {

     friend class TaggedProtoOperations<Rooted<TaggedProto> >;

     const TaggedProto *extract() const {

         return static_cast<const Rooted<TaggedProto> *>(this)->address();

     }

 };

 class CallObject;

 /*

  * Execution Mode Overview

  *

  * JavaScript code can execute either sequentially or in parallel, such as in

  * PJS. Functions which behave identically in either execution mode can take a

  * ThreadSafeContext, and functions which have similar but not identical

  * behavior between execution modes can be templated on the mode. Such

  * functions use a context parameter type from ExecutionModeTraits below

  * indicating whether they are only permitted constrained operations (such as

  * thread safety, and side effects limited to being thread-local), or whether

  * they can have arbitrary side effects.

  */

 enum ExecutionMode {

     /* Normal JavaScript execution. */

     SequentialExecution,

     /*

      * JavaScript code to be executed in parallel worker threads in PJS in a

      * fork join fashion.

      */

     ParallelExecution,

     /*

      * Modes after this point are internal and are not counted in

      * NumExecutionModes below.

      */

     /*

      * MIR analysis performed when invoking 'new' on a script, to determine

      * definite properties. Used by the optimizing JIT.

      */

     DefinitePropertiesAnalysis,

     /*

      * MIR analysis performed when executing a script which uses its arguments,

      * when it is not known whether a lazy arguments value can be used.

      */

     ArgumentsUsageAnalysis

 };

 /*

  * Not as part of the enum so we don't get warnings about unhandled enum

  * values.

  */

 static const unsigned NumExecutionModes = ParallelExecution + 1;

 template <ExecutionMode mode>

 struct ExecutionModeTraits

 {

 };

 template <> struct ExecutionModeTraits<SequentialExecution>

 {

     typedef JSContext * ContextType;

     typedef ExclusiveContext * ExclusiveContextType;

     static inline JSContext *toContextType(ExclusiveContext *cx);

 };

 template <> struct ExecutionModeTraits<ParallelExecution>

 {

     typedef ForkJoinContext * ContextType;

     typedef ForkJoinContext * ExclusiveContextType;

     static inline ForkJoinContext *toContextType(ForkJoinContext *cx) { return cx; }

 };

 namespace jit {

     struct IonScript;

     class IonAllocPolicy;

     class TempAllocator;

 }

 namespace types {

 class TypeZone;

 class TypeSet;

 class TypeObjectKey;

 /*

  * Information about a single concrete type. We pack this into a single word,

  * where small values are particular primitive or other singleton types, and

  * larger values are either specific JS objects or type objects.

  */

 class Type

 {

     uintptr_t data;

     Type(uintptr_t data) : data(data) {}

   public:

     uintptr_t raw() const { return data; }

     bool isPrimitive() const {

         return data < JSVAL_TYPE_OBJECT;

     }

     bool isPrimitive(JSValueType type) const {

         JS_ASSERT(type < JSVAL_TYPE_OBJECT);

         return (uintptr_t) type == data;

     }

     JSValueType primitive() const {

         JS_ASSERT(isPrimitive());

         return (JSValueType) data;

     }

     bool isMagicArguments() const {

         return primitive() == JSVAL_TYPE_MAGIC;

     }

     bool isSomeObject() const {

         return data == JSVAL_TYPE_OBJECT || data > JSVAL_TYPE_UNKNOWN;

     }

     bool isAnyObject() const {

         return data == JSVAL_TYPE_OBJECT;

     }

     bool isUnknown() const {

         return data == JSVAL_TYPE_UNKNOWN;

     }

     /* Accessors for types that are either JSObject or TypeObject. */

     bool isObject() const {

         JS_ASSERT(!isAnyObject() && !isUnknown());

         return data > JSVAL_TYPE_UNKNOWN;

     }

     bool isObjectUnchecked() const {

         return data > JSVAL_TYPE_UNKNOWN;

     }

     inline TypeObjectKey *objectKey() const;

     /* Accessors for JSObject types */

     bool isSingleObject() const {

         return isObject() && !!(data & 1);

     }

     inline JSObject *singleObject() const;

     /* Accessors for TypeObject types */

     bool isTypeObject() const {

         return isObject() && !(data & 1);

     }

     inline TypeObject *typeObject() const;

     bool operator == (Type o) const { return data == o.data; }

     bool operator != (Type o) const { return data != o.data; }

     static inline Type UndefinedType() { return Type(JSVAL_TYPE_UNDEFINED); }

     static inline Type NullType()      { return Type(JSVAL_TYPE_NULL); }

     static inline Type BooleanType()   { return Type(JSVAL_TYPE_BOOLEAN); }

     static inline Type Int32Type()     { return Type(JSVAL_TYPE_INT32); }

     static inline Type DoubleType()    { return Type(JSVAL_TYPE_DOUBLE); }

     static inline Type StringType()    { return Type(JSVAL_TYPE_STRING); }

     static inline Type MagicArgType()  { return Type(JSVAL_TYPE_MAGIC); }

     static inline Type AnyObjectType() { return Type(JSVAL_TYPE_OBJECT); }

     static inline Type UnknownType()   { return Type(JSVAL_TYPE_UNKNOWN); }

     static inline Type PrimitiveType(JSValueType type) {

         JS_ASSERT(type < JSVAL_TYPE_UNKNOWN);

         return Type(type);

     }

     static inline Type ObjectType(JSObject *obj);

     static inline Type ObjectType(TypeObject *obj);

     static inline Type ObjectType(TypeObjectKey *obj);

 };

 /* Get the type of a jsval, or zero for an unknown special value. */

 inline Type GetValueType(const Value &val);

 /*

  * Get the type of a possibly optimized out value. This generally only

  * happens on unconditional type monitors on bailing out of Ion, such as

  * for argument and local types.

  */

 inline Type GetMaybeOptimizedOutValueType(const Value &val);

 /*

  * Type inference memory management overview.

  *

  * Type information about the values observed within scripts and about the

  * contents of the heap is accumulated as the program executes. Compilation

  * accumulates constraints relating type information on the heap with the

  * compilations that should be invalidated when those types change. Type

  * information and constraints are allocated in the zone's typeLifoAlloc,

  * and on GC all data referring to live things is copied into a new allocator.

  * Thus, type set and constraints only hold weak references.

  */

 /*

  * A constraint which listens to additions to a type set and propagates those

  * changes to other type sets.

  */

 class TypeConstraint

 {

 public:

     /* Next constraint listening to the same type set. */

     TypeConstraint *next;

     TypeConstraint()

         : next(nullptr)

     {}

     /* Debugging name for this kind of constraint. */

     virtual const char *kind() = 0;

     /* Register a new type for the set this constraint is listening to. */

     virtual void newType(JSContext *cx, TypeSet *source, Type type) = 0;

     /*

      * For constraints attached to an object property's type set, mark the

      * property as having its configuration changed.

      */

     virtual void newPropertyState(JSContext *cx, TypeSet *source) {}

     /*

      * For constraints attached to the JSID_EMPTY type set on an object,

      * indicate a change in one of the object's dynamic property flags or other

      * state.

      */

     virtual void newObjectState(JSContext *cx, TypeObject *object) {}

     /*

      * If the data this constraint refers to is still live, copy it into the

      * zone's new allocator. Type constraints only hold weak references.

      */

     virtual bool sweep(TypeZone &zone, TypeConstraint **res) = 0;

 };

 /* Flags and other state stored in TypeSet::flags */

 enum MOZ_ENUM_TYPE(uint32_t) {

     TYPE_FLAG_UNDEFINED =  0x1,

     TYPE_FLAG_NULL      =  0x2,

     TYPE_FLAG_BOOLEAN   =  0x4,

     TYPE_FLAG_INT32     =  0x8,

     TYPE_FLAG_DOUBLE    = 0x10,

     TYPE_FLAG_STRING    = 0x20,

     TYPE_FLAG_LAZYARGS  = 0x40,

     TYPE_FLAG_ANYOBJECT = 0x80,

     /* Mask containing all primitives */

     TYPE_FLAG_PRIMITIVE = TYPE_FLAG_UNDEFINED | TYPE_FLAG_NULL | TYPE_FLAG_BOOLEAN |

                           TYPE_FLAG_INT32 | TYPE_FLAG_DOUBLE | TYPE_FLAG_STRING,

     /* Mask/shift for the number of objects in objectSet */

     TYPE_FLAG_OBJECT_COUNT_MASK   = 0x1f00,

     TYPE_FLAG_OBJECT_COUNT_SHIFT  = 8,

     TYPE_FLAG_OBJECT_COUNT_LIMIT  =

         TYPE_FLAG_OBJECT_COUNT_MASK >> TYPE_FLAG_OBJECT_COUNT_SHIFT,

     /* Whether the contents of this type set are totally unknown. */

     TYPE_FLAG_UNKNOWN             = 0x00002000,

     /* Mask of normal type flags on a type set. */

     TYPE_FLAG_BASE_MASK           = 0x000020ff,

     /* Additional flags for HeapTypeSet sets. */

     /*

      * Whether the property has ever been deleted or reconfigured to behave

      * differently from a plain data property, other than making the property

      * non-writable.

      */

     TYPE_FLAG_NON_DATA_PROPERTY = 0x00004000,

     /* Whether the property has ever been made non-writable. */

     TYPE_FLAG_NON_WRITABLE_PROPERTY = 0x00008000,

     /*

      * Whether the property is definitely in a particular slot on all objects

      * from which it has not been deleted or reconfigured. For singletons

      * this may be a fixed or dynamic slot, and for other objects this will be

      * a fixed slot.

      *

      * If the property is definite, mask and shift storing the slot + 1.

      * Otherwise these bits are clear.

      */

     TYPE_FLAG_DEFINITE_MASK       = 0xffff0000,

     TYPE_FLAG_DEFINITE_SHIFT      = 16

 };

 typedef uint32_t TypeFlags;

 /* Flags and other state stored in TypeObject::flags */

 enum MOZ_ENUM_TYPE(uint32_t) {

     /* Whether this type object is associated with some allocation site. */

     OBJECT_FLAG_FROM_ALLOCATION_SITE  = 0x1,

     /* If set, addendum information should not be installed on this object. */

     OBJECT_FLAG_ADDENDUM_CLEARED      = 0x2,

     /*

      * If set, the object's prototype might be in the nursery and can't be

      * used during Ion compilation (which may be occurring off thread).

      */

     OBJECT_FLAG_NURSERY_PROTO         = 0x4,

     /*

      * Whether we have ensured all type sets in the compartment contain

      * ANYOBJECT instead of this object.

      */

     OBJECT_FLAG_SETS_MARKED_UNKNOWN   = 0x8,

     /* Mask/shift for the number of properties in propertySet */

     OBJECT_FLAG_PROPERTY_COUNT_MASK   = 0xfff0,

     OBJECT_FLAG_PROPERTY_COUNT_SHIFT  = 4,

     OBJECT_FLAG_PROPERTY_COUNT_LIMIT  =

         OBJECT_FLAG_PROPERTY_COUNT_MASK >> OBJECT_FLAG_PROPERTY_COUNT_SHIFT,

     /* Whether any objects this represents may have sparse indexes. */

     OBJECT_FLAG_SPARSE_INDEXES        = 0x00010000,

     /* Whether any objects this represents may not have packed dense elements. */

     OBJECT_FLAG_NON_PACKED            = 0x00020000,

     /*

      * Whether any objects this represents may be arrays whose length does not

      * fit in an int32.

      */

     OBJECT_FLAG_LENGTH_OVERFLOW       = 0x00040000,

     /* Whether any objects have been iterated over. */

     OBJECT_FLAG_ITERATED              = 0x00080000,

     /* For a global object, whether flags were set on the RegExpStatics. */

     OBJECT_FLAG_REGEXP_FLAGS_SET      = 0x00100000,

     /*

      * For the function on a run-once script, whether the function has actually

      * run multiple times.

      */

     OBJECT_FLAG_RUNONCE_INVALIDATED   = 0x00200000,

     /*

      * Whether objects with this type should be allocated directly in the

      * tenured heap.

      */

     OBJECT_FLAG_PRE_TENURE            = 0x00400000,

     /*

      * Whether all properties of this object are considered unknown.

      * If set, all other flags in DYNAMIC_MASK will also be set.

      */

     OBJECT_FLAG_UNKNOWN_PROPERTIES    = 0x00800000,

     /* Flags which indicate dynamic properties of represented objects. */

     OBJECT_FLAG_DYNAMIC_MASK          = 0x00ff0000,

     /* Mask for objects created with unknown properties. */

     OBJECT_FLAG_UNKNOWN_MASK =

         OBJECT_FLAG_DYNAMIC_MASK

       | OBJECT_FLAG_SETS_MARKED_UNKNOWN

 };

 typedef uint32_t TypeObjectFlags;

 class StackTypeSet;

 class HeapTypeSet;

 class TemporaryTypeSet;

 /*

  * Information about the set of types associated with an lvalue. There are

  * three kinds of type sets:

  *

  * - StackTypeSet are associated with TypeScripts, for arguments and values

  *   observed at property reads. These are implicitly frozen on compilation

  *   and do not have constraints attached to them.

  *

  * - HeapTypeSet are associated with the properties of TypeObjects. These

  *   may have constraints added to them to trigger invalidation of compiled

  *   code.

  *

  * - TemporaryTypeSet are created during compilation and do not outlive

  *   that compilation.

  */

 class TypeSet

 {

   protected:

     /* Flags for this type set. */

     TypeFlags flags;

     /* Possible objects this type set can represent. */

     TypeObjectKey **objectSet;

   public:

     TypeSet()

       : flags(0), objectSet(nullptr)

     {}

     void print();

     /* Whether this set contains a specific type. */

     inline bool hasType(Type type) const;

     TypeFlags baseFlags() const { return flags & TYPE_FLAG_BASE_MASK; }

     bool unknown() const { return !!(flags & TYPE_FLAG_UNKNOWN); }

     bool unknownObject() const { return !!(flags & (TYPE_FLAG_UNKNOWN | TYPE_FLAG_ANYOBJECT)); }

     bool empty() const { return !baseFlags() && !baseObjectCount(); }

     bool hasAnyFlag(TypeFlags flags) const {

         JS_ASSERT((flags & TYPE_FLAG_BASE_MASK) == flags);

         return !!(baseFlags() & flags);

     }

     bool nonDataProperty() const {

         return flags & TYPE_FLAG_NON_DATA_PROPERTY;

     }

     bool nonWritableProperty() const {

         return flags & TYPE_FLAG_NON_WRITABLE_PROPERTY;

     }

     bool definiteProperty() const { return flags & TYPE_FLAG_DEFINITE_MASK; }

     unsigned definiteSlot() const {

         JS_ASSERT(definiteProperty());

         return (flags >> TYPE_FLAG_DEFINITE_SHIFT) - 1;

     }

     /* Join two type sets into a new set. The result should not be modified further. */

     static TemporaryTypeSet *unionSets(TypeSet *a, TypeSet *b, LifoAlloc *alloc);

     /* Add a type to this set using the specified allocator. */

     void addType(Type type, LifoAlloc *alloc);

     /* Get a list of all types in this set. */

     typedef Vector<Type, 1, SystemAllocPolicy> TypeList;

     bool enumerateTypes(TypeList *list);

     /*

      * Iterate through the objects in this set. getObjectCount overapproximates

      * in the hash case (see SET_ARRAY_SIZE in jsinferinlines.h), and getObject

      * may return nullptr.

      */

     inline unsigned getObjectCount() const;

     inline TypeObjectKey *getObject(unsigned i) const;

     inline JSObject *getSingleObject(unsigned i) const;

     inline TypeObject *getTypeObject(unsigned i) const;

     /* The Class of an object in this set. */

     inline const Class *getObjectClass(unsigned i) const;

     bool canSetDefinite(unsigned slot) {

         // Note: the cast is required to work around an MSVC issue.

         return (slot + 1) <= (unsigned(TYPE_FLAG_DEFINITE_MASK) >> TYPE_FLAG_DEFINITE_SHIFT);

     }

     void setDefinite(unsigned slot) {

         JS_ASSERT(canSetDefinite(slot));

         flags |= ((slot + 1) << TYPE_FLAG_DEFINITE_SHIFT);

         JS_ASSERT(definiteSlot() == slot);

     }

     /* Whether any values in this set might have the specified type. */

     bool mightBeMIRType(jit::MIRType type);

     /*

      * Get whether this type set is known to be a subset of other.

      * This variant doesn't freeze constraints. That variant is called knownSubset

      */

     bool isSubset(TypeSet *other);

     /* Forward all types in this set to the specified constraint. */

     bool addTypesToConstraint(JSContext *cx, TypeConstraint *constraint);

     // Clone a type set into an arbitrary allocator.

     TemporaryTypeSet *clone(LifoAlloc *alloc) const;

     bool clone(LifoAlloc *alloc, TemporaryTypeSet *result) const;

     // Create a new TemporaryTypeSet where undefined and/or null has been filtered out.

     TemporaryTypeSet *filter(LifoAlloc *alloc, bool filterUndefined, bool filterNull) const;

   protected:

     uint32_t baseObjectCount() const {

         return (flags & TYPE_FLAG_OBJECT_COUNT_MASK) >> TYPE_FLAG_OBJECT_COUNT_SHIFT;

     }

     inline void setBaseObjectCount(uint32_t count);

     void clearObjects();

 };

 /* Superclass common to stack and heap type sets. */

 class ConstraintTypeSet : public TypeSet

 {

   public:

     /* Chain of constraints which propagate changes out from this type set. */

     TypeConstraint *constraintList;

     ConstraintTypeSet() : constraintList(nullptr) {}

     /*

      * Add a type to this set, calling any constraint handlers if this is a new

      * possible type.

      */

     void addType(ExclusiveContext *cx, Type type);

     /* Add a new constraint to this set. */

     bool addConstraint(JSContext *cx, TypeConstraint *constraint, bool callExisting = true);

     inline void sweep(JS::Zone *zone, bool *oom);

 };

 class StackTypeSet : public ConstraintTypeSet

 {

   public:

 };

 class HeapTypeSet : public ConstraintTypeSet

 {

     inline void newPropertyState(ExclusiveContext *cx);

   public:

     /* Mark this type set as representing a non-data property. */

     inline void setNonDataProperty(ExclusiveContext *cx);

     inline void setNonDataPropertyIgnoringConstraints(); // Variant for use during GC.

     /* Mark this type set as representing a non-writable property. */

     inline void setNonWritableProperty(ExclusiveContext *cx);

 };

 class CompilerConstraintList;

 CompilerConstraintList *

 NewCompilerConstraintList(jit::TempAllocator &alloc);

 class TemporaryTypeSet : public TypeSet

 {

   public:

     TemporaryTypeSet() {}

     TemporaryTypeSet(Type type);

     TemporaryTypeSet(uint32_t flags, TypeObjectKey **objectSet) {

         this->flags = flags;

         this->objectSet = objectSet;

     }

     /*

      * Constraints for JIT compilation.

      *

      * Methods for JIT compilation. These must be used when a script is

      * currently being compiled (see AutoEnterCompilation) and will add

      * constraints ensuring that if the return value change in the future due

      * to new type information, the script's jitcode will be discarded.

      */

     /* Get any type tag which all values in this set must have. */

     jit::MIRType getKnownMIRType();

     bool isMagicArguments() { return getKnownMIRType() == jit::MIRType_MagicOptimizedArguments; }

     /* Whether this value may be an object. */

     bool maybeObject() { return unknownObject() || baseObjectCount() > 0; }

     /*

      * Whether this typeset represents a potentially sentineled object value:

      * the value may be an object or null or undefined.

      * Returns false if the value cannot ever be an object.

      */

     bool objectOrSentinel() {

         TypeFlags flags = TYPE_FLAG_UNDEFINED | TYPE_FLAG_NULL | TYPE_FLAG_ANYOBJECT;

         if (baseFlags() & (~flags & TYPE_FLAG_BASE_MASK))

             return false;

         return hasAnyFlag(TYPE_FLAG_ANYOBJECT) || baseObjectCount() > 0;

     }

     /* Whether the type set contains objects with any of a set of flags. */

     bool hasObjectFlags(CompilerConstraintList *constraints, TypeObjectFlags flags);

     /* Get the class shared by all objects in this set, or nullptr. */

     const Class *getKnownClass();

     /* Result returned from forAllClasses */

     enum ForAllResult {

         EMPTY=1,                // Set empty

         ALL_TRUE,               // Set not empty and predicate returned true for all classes

         ALL_FALSE,              // Set not empty and predicate returned false for all classes

         MIXED,                  // Set not empty and predicate returned false for some classes

                                 // and true for others, or set contains an unknown or non-object

                                 // type

     };

     /* Apply func to the members of the set and return an appropriate result.

      * The iteration may end early if the result becomes known early.

      */

     ForAllResult forAllClasses(bool (*func)(const Class *clasp));

     /* Get the prototype shared by all objects in this set, or nullptr. */

     JSObject *getCommonPrototype();

     /* Get the typed array type of all objects in this set, or TypedArrayObject::TYPE_MAX. */

     int getTypedArrayType();

     /* Whether all objects have JSCLASS_IS_DOMJSCLASS set. */

     bool isDOMClass();

     /* Whether clasp->isCallable() is true for one or more objects in this set. */

     bool maybeCallable();

     /* Whether clasp->emulatesUndefined() is true for one or more objects in this set. */

     bool maybeEmulatesUndefined();

     /* Get the single value which can appear in this type set, otherwise nullptr. */

     JSObject *getSingleton();

     /* Whether any objects in the type set needs a barrier on id. */

     bool propertyNeedsBarrier(CompilerConstraintList *constraints, jsid id);

     /*

      * Whether this set contains all types in other, except (possibly) the

      * specified type.

      */

     bool filtersType(const TemporaryTypeSet *other, Type type) const;

     enum DoubleConversion {

         /* All types in the set should use eager double conversion. */

         AlwaysConvertToDoubles,

         /* Some types in the set should use eager double conversion. */

         MaybeConvertToDoubles,

         /* No types should use eager double conversion. */

         DontConvertToDoubles,

         /* Some types should use eager double conversion, others cannot. */

         AmbiguousDoubleConversion

     };

     /*

      * Whether known double optimizations are possible for element accesses on

      * objects in this type set.

      */

     DoubleConversion convertDoubleElements(CompilerConstraintList *constraints);

 };

 bool

 AddClearDefiniteGetterSetterForPrototypeChain(JSContext *cx, TypeObject *type, HandleId id);

 bool

 AddClearDefiniteFunctionUsesInScript(JSContext *cx, TypeObject *type,

                                      JSScript *script, JSScript *calleeScript);

 /* Is this a reasonable PC to be doing inlining on? */

 inline bool isInlinableCall(jsbytecode *pc);

 /* Type information about a property. */

 struct Property

 {

     /* Identifier for this property, JSID_VOID for the aggregate integer index property. */

     HeapId id;

     /* Possible types for this property, including types inherited from prototypes. */

     HeapTypeSet types;

     Property(jsid id)

       : id(id)

     {}

     Property(const Property &o)

       : id(o.id.get()), types(o.types)

     {}

     static uint32_t keyBits(jsid id) { return uint32_t(JSID_BITS(id)); }

     static jsid getKey(Property *p) { return p->id; }

 };

 struct TypeNewScript;

 struct TypeTypedObject;

 struct TypeObjectAddendum

 {

     enum Kind {

         NewScript,

         TypedObject

     };

     TypeObjectAddendum(Kind kind);

     const Kind kind;

     bool isNewScript() {

         return kind == NewScript;

     }

     TypeNewScript *asNewScript() {

         JS_ASSERT(isNewScript());

         return (TypeNewScript*) this;

     }

     bool isTypedObject() {

         return kind == TypedObject;

     }

     TypeTypedObject *asTypedObject() {

         JS_ASSERT(isTypedObject());

         return (TypeTypedObject*) this;

     }

     static inline void writeBarrierPre(TypeObjectAddendum *type);

     static void writeBarrierPost(TypeObjectAddendum *newScript, void *addr) {}

 };

 /*

  * Information attached to a TypeObject if it is always constructed using 'new'

  * on a particular script. This is used to manage state related to the definite

  * properties on the type object: these definite properties depend on type

  * information which could change as the script executes (e.g. a scripted

  * setter is added to a prototype object), and we need to ensure both that the

  * appropriate type constraints are in place when necessary, and that we can

  * remove the definite property information and repair the JS stack if the

  * constraints are violated.

  */

 struct TypeNewScript : public TypeObjectAddendum

 {

     TypeNewScript();

     HeapPtrFunction fun;

     /*

      * Template object to use for newly constructed objects. Reflects all

      * definite properties the object will have and the allocation kind to use

      * for the object. The allocation kind --- and template object itself ---

      * is subject to change if objects allocated with this type are given

      * dynamic slots later on due to new properties being added after the

      * constructor function finishes.

      */

     HeapPtrObject templateObject;

     /*

      * Order in which properties become initialized. We need this in case a

      * scripted setter is added to one of the object's prototypes while it is

      * in the middle of being initialized, so we can walk the stack and fixup

      * any objects which look for in-progress objects which were prematurely

      * set with their final shape. Property assignments in inner frames are

      * preceded by a series of SETPROP_FRAME entries specifying the stack down

      * to the frame containing the write.

      */

     struct Initializer {

         enum Kind {

             SETPROP,

             SETPROP_FRAME,

             DONE

         } kind;

         uint32_t offset;

         Initializer(Kind kind, uint32_t offset)

           : kind(kind), offset(offset)

         {}

     };

     Initializer *initializerList;

     static inline void writeBarrierPre(TypeNewScript *newScript);

 };

 struct TypeTypedObject : public TypeObjectAddendum

 {

   private:

     HeapPtrObject descr_;

   public:

     TypeTypedObject(Handle<TypeDescr*> descr);

     HeapPtrObject &descrHeapPtr() {

         return descr_;

     }

     TypeDescr &descr();

 };

 /*

  * Lazy type objects overview.

  *

  * Type objects which represent at most one JS object are constructed lazily.

  * These include types for native functions, standard classes, scripted

  * functions defined at the top level of global/eval scripts, and in some

  * other cases. Typical web workloads often create many windows (and many

  * copies of standard natives) and many scripts, with comparatively few

  * non-singleton types.

  *

  * We can recover the type information for the object from examining it,

  * so don't normally track the possible types of its properties as it is

  * updated. Property type sets for the object are only constructed when an

  * analyzed script attaches constraints to it: the script is querying that

  * property off the object or another which delegates to it, and the analysis

  * information is sensitive to changes in the property's type. Future changes

  * to the property (whether those uncovered by analysis or those occurring

  * in the VM) will treat these properties like those of any other type object.

  */

 /* Type information about an object accessed by a script. */

 struct TypeObject : gc::BarrieredCell<TypeObject>

 {

   private:

     /* Class shared by object using this type. */

     const Class *clasp_;

     /* Prototype shared by objects using this type. */

     HeapPtrObject proto_;

     /*

      * Whether there is a singleton JS object with this type. That JS object

      * must appear in type sets instead of this; we include the back reference

      * here to allow reverting the JS object to a lazy type.

      */

     HeapPtrObject singleton_;

   public:

     const Class *clasp() const {

         return clasp_;

     }

     void setClasp(const Class *clasp) {

         JS_ASSERT(singleton());

         clasp_ = clasp;

     }

     TaggedProto proto() const {

         return TaggedProto(proto_);

     }

     JSObject *singleton() const {

         return singleton_;

     }

     // For use during marking, don't call otherwise.

     HeapPtrObject &protoRaw() { return proto_; }

     HeapPtrObject &singletonRaw() { return singleton_; }

     void setProto(JSContext *cx, TaggedProto proto);

     void setProtoUnchecked(TaggedProto proto) {

         proto_ = proto.raw();

     }

     void initSingleton(JSObject *singleton) {

         singleton_ = singleton;

     }

     /*

      * Value held by singleton if this is a standin type for a singleton JS

      * object whose type has not been constructed yet.

      */

     static const size_t LAZY_SINGLETON = 1;

     bool lazy() const { return singleton() == (JSObject *) LAZY_SINGLETON; }

   private:

     /* Flags for this object. */

     TypeObjectFlags flags_;

     /*

      * This field allows various special classes of objects to attach

      * additional information to a type object:

      *

      * - `TypeNewScript`: If addendum is a `TypeNewScript`, it

      *   indicates that objects of this type have always been

      *   constructed using 'new' on the specified script, which adds

      *   some number of properties to the object in a definite order

      *   before the object escapes.

      */

     HeapPtr<TypeObjectAddendum> addendum;

   public:

     TypeObjectFlags flags() const {

         return flags_;

     }

     void addFlags(TypeObjectFlags flags) {

         flags_ |= flags;

     }

     void clearFlags(TypeObjectFlags flags) {

         flags_ &= ~flags;

     }

     bool hasNewScript() const {

         return addendum && addendum->isNewScript();

     }

     TypeNewScript *newScript() {

         return addendum->asNewScript();

     }

     bool hasTypedObject() {

         return addendum && addendum->isTypedObject();

     }

     TypeTypedObject *typedObject() {

         return addendum->asTypedObject();

     }

     void setAddendum(TypeObjectAddendum *addendum);

     /*

      * Tag the type object for a binary data type descriptor, instance,

      * or handle with the type representation of the data it points at.

      * If this type object is already tagged with a binary data addendum,

      * this addendum must already be associated with the same TypeRepresentation,

      * and the method has no effect.

      */

     bool addTypedObjectAddendum(JSContext *cx, Handle<TypeDescr*> descr);

   private:

     /*

      * Properties of this object. This may contain JSID_VOID, representing the

      * types of all integer indexes of the object, and/or JSID_EMPTY, holding

      * constraints listening to changes to the object's state.

      *

      * The type sets in the properties of a type object describe the possible

      * values that can be read out of that property in actual JS objects.

      * Properties only account for native properties (those with a slot and no

      * specialized getter hook) and the elements of dense arrays. For accesses

      * on such properties, the correspondence is as follows:

      *

      * 1. If the type has unknownProperties(), the possible properties and

      *    value types for associated JSObjects are unknown.

      *

      * 2. Otherwise, for any JSObject obj with TypeObject type, and any jsid id

      *    which is a property in obj, before obj->getProperty(id) the property

      *    in type for id must reflect the result of the getProperty.

      *

      *    There is an exception for properties of global JS objects which

      *    are undefined at the point where the property was (lazily) generated.

      *    In such cases the property type set will remain empty, and the

      *    'undefined' type will only be added after a subsequent assignment or

      *    deletion. After these properties have been assigned a defined value,

      *    the only way they can become undefined again is after such an assign

      *    or deletion.

      *

      *    There is another exception for array lengths, which are special cased

      *    by the compiler and VM and are not reflected in property types.

      *

      * We establish these by using write barriers on calls to setProperty and

      * defineProperty which are on native properties, and on any jitcode which

      * might update the property with a new type.

      */

     Property **propertySet;

   public:

     /* If this is an interpreted function, the function object. */

     HeapPtrFunction interpretedFunction;

 #if JS_BITS_PER_WORD == 32

     uint32_t padding;

 #endif

     inline TypeObject(const Class *clasp, TaggedProto proto, TypeObjectFlags initialFlags);

     bool hasAnyFlags(TypeObjectFlags flags) {

         JS_ASSERT((flags & OBJECT_FLAG_DYNAMIC_MASK) == flags);

         return !!(this->flags() & flags);

     }

     bool hasAllFlags(TypeObjectFlags flags) {

         JS_ASSERT((flags & OBJECT_FLAG_DYNAMIC_MASK) == flags);

         return (this->flags() & flags) == flags;

     }

     bool unknownProperties() {

         JS_ASSERT_IF(flags() & OBJECT_FLAG_UNKNOWN_PROPERTIES,

                      hasAllFlags(OBJECT_FLAG_DYNAMIC_MASK));

         return !!(flags() & OBJECT_FLAG_UNKNOWN_PROPERTIES);

     }

     bool shouldPreTenure() {

         return hasAnyFlags(OBJECT_FLAG_PRE_TENURE) && !unknownProperties();

     }

     bool hasTenuredProto() const {

         return !(flags() & OBJECT_FLAG_NURSERY_PROTO);

     }

     gc::InitialHeap initialHeap(CompilerConstraintList *constraints);

     bool canPreTenure() {

         // Only types associated with particular allocation sites or 'new'

         // scripts can be marked as needing pretenuring. Other types can be

         // used for different purposes across the compartment and can't use

         // this bit reliably.

         if (unknownProperties())

             return false;

         return (flags() & OBJECT_FLAG_FROM_ALLOCATION_SITE) || hasNewScript();

     }

     void setShouldPreTenure(ExclusiveContext *cx) {

         JS_ASSERT(canPreTenure());

         setFlags(cx, OBJECT_FLAG_PRE_TENURE);

     }

     /*

      * Get or create a property of this object. Only call this for properties which

      * a script accesses explicitly.

      */

     inline HeapTypeSet *getProperty(ExclusiveContext *cx, jsid id);

     /* Get a property only if it already exists. */

     inline HeapTypeSet *maybeGetProperty(jsid id);

     inline unsigned getPropertyCount();

     inline Property *getProperty(unsigned i);

     /* Helpers */

     void updateNewPropertyTypes(ExclusiveContext *cx, jsid id, HeapTypeSet *types);

     bool addDefiniteProperties(ExclusiveContext *cx, JSObject *obj);

     bool matchDefiniteProperties(HandleObject obj);

     void addPrototype(JSContext *cx, TypeObject *proto);

     void addPropertyType(ExclusiveContext *cx, jsid id, Type type);

     void addPropertyType(ExclusiveContext *cx, jsid id, const Value &value);

     void markPropertyNonData(ExclusiveContext *cx, jsid id);

     void markPropertyNonWritable(ExclusiveContext *cx, jsid id);

     void markStateChange(ExclusiveContext *cx);

     void setFlags(ExclusiveContext *cx, TypeObjectFlags flags);

     void markUnknown(ExclusiveContext *cx);

     void clearAddendum(ExclusiveContext *cx);

     void clearNewScriptAddendum(ExclusiveContext *cx);

     void clearTypedObjectAddendum(ExclusiveContext *cx);

     void maybeClearNewScriptAddendumOnOOM();

     bool isPropertyNonData(jsid id);

     bool isPropertyNonWritable(jsid id);

     void print();

     inline void clearProperties();

     inline void sweep(FreeOp *fop, bool *oom);

     size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;

     /*

      * Type objects don't have explicit finalizers. Memory owned by a type

      * object pending deletion is released when weak references are sweeped

      * from all the compartment's type objects.

      */

     void finalize(FreeOp *fop) {}

     static inline ThingRootKind rootKind() { return THING_ROOT_TYPE_OBJECT; }

     static inline uint32_t offsetOfClasp() {

         return offsetof(TypeObject, clasp_);

     }

     static inline uint32_t offsetOfProto() {

         return offsetof(TypeObject, proto_);

     }

   private:

     inline uint32_t basePropertyCount() const;

     inline void setBasePropertyCount(uint32_t count);

     static void staticAsserts() {

         JS_STATIC_ASSERT(offsetof(TypeObject, proto_) == offsetof(js::shadow::TypeObject, proto));

     }

 };

 /*

  * Entries for the per-compartment set of type objects which are 'new' types to

  * use for some prototype and constructed with an optional script. This also

  * includes entries for the set of lazy type objects in the compartment, which

  * use a null script (though there are only a few of these per compartment).

  */

 struct TypeObjectWithNewScriptEntry

 {

     ReadBarriered<TypeObject> object;

     // Note: This pointer is only used for equality and does not need a read barrier.

     JSFunction *newFunction;

     TypeObjectWithNewScriptEntry(TypeObject *object, JSFunction *newFunction)

       : object(object), newFunction(newFunction)

     {}

     struct Lookup {

         const Class *clasp;

         TaggedProto hashProto;

         TaggedProto matchProto;

         JSFunction *newFunction;

         Lookup(const Class *clasp, TaggedProto proto, JSFunction *newFunction)

           : clasp(clasp), hashProto(proto), matchProto(proto), newFunction(newFunction)

         {}

 #ifdef JSGC_GENERATIONAL

         /*

          * For use by generational post barriers only.  Look up an entry whose

          * proto has been moved, but was hashed with the original value.

          */

         Lookup(const Class *clasp, TaggedProto hashProto, TaggedProto matchProto, JSFunction *newFunction)

             : clasp(clasp), hashProto(hashProto), matchProto(matchProto), newFunction(newFunction)

         {}

 #endif

     };

     static inline HashNumber hash(const Lookup &lookup);

     static inline bool match(const TypeObjectWithNewScriptEntry &key, const Lookup &lookup);

     static void rekey(TypeObjectWithNewScriptEntry &k, const TypeObjectWithNewScriptEntry& newKey) { k = newKey; }

 };

 typedef HashSet<TypeObjectWithNewScriptEntry,

                 TypeObjectWithNewScriptEntry,

                 SystemAllocPolicy> TypeObjectWithNewScriptSet;

 /* Whether to use a new type object when calling 'new' at script/pc. */

 bool

 UseNewType(JSContext *cx, JSScript *script, jsbytecode *pc);

 bool

 UseNewTypeForClone(JSFunction *fun);

 /*

  * Whether Array.prototype, or an object on its proto chain, has an

  * indexed property.

  */

 bool

 ArrayPrototypeHasIndexedProperty(CompilerConstraintList *constraints, JSScript *script);

 /* Whether obj or any of its prototypes have an indexed property. */

 bool

 TypeCanHaveExtraIndexedProperties(CompilerConstraintList *constraints, TemporaryTypeSet *types);

 /* Persistent type information for a script, retained across GCs. */

 class TypeScript

 {

     friend class ::JSScript;

     // Variable-size array

     StackTypeSet typeArray_[1];

   public:

     /* Array of type type sets for variables and JOF_TYPESET ops. */

     StackTypeSet *typeArray() const {

         // Ensure typeArray_ is the last data member of TypeScript.

         JS_STATIC_ASSERT(sizeof(TypeScript) ==

             sizeof(typeArray_) + offsetof(TypeScript, typeArray_));

         return const_cast<StackTypeSet *>(typeArray_);

     }

     static inline size_t SizeIncludingTypeArray(size_t arraySize) {

         // Ensure typeArray_ is the last data member of TypeScript.

         JS_STATIC_ASSERT(sizeof(TypeScript) ==

             sizeof(StackTypeSet) + offsetof(TypeScript, typeArray_));

         return offsetof(TypeScript, typeArray_) + arraySize * sizeof(StackTypeSet);

     }

     static inline unsigned NumTypeSets(JSScript *script);

     static inline StackTypeSet *ThisTypes(JSScript *script);

     static inline StackTypeSet *ArgTypes(JSScript *script, unsigned i);

     /* Get the type set for values observed at an opcode. */

     static inline StackTypeSet *BytecodeTypes(JSScript *script, jsbytecode *pc);

     template <typename TYPESET>

     static inline TYPESET *BytecodeTypes(JSScript *script, jsbytecode *pc, uint32_t *bytecodeMap,

                                          uint32_t *hint, TYPESET *typeArray);

     /* Get a type object for an allocation site in this script. */

     static inline TypeObject *InitObject(JSContext *cx, JSScript *script, jsbytecode *pc,

                                          JSProtoKey kind);

     /*

      * Monitor a bytecode pushing any value. This must be called for any opcode

      * which is JOF_TYPESET, and where either the script has not been analyzed

      * by type inference or where the pc has type barriers. For simplicity, we

      * always monitor JOF_TYPESET opcodes in the interpreter and stub calls,

      * and only look at barriers when generating JIT code for the script.

      */

     static inline void Monitor(JSContext *cx, JSScript *script, jsbytecode *pc,

                                const js::Value &val);

     static inline void Monitor(JSContext *cx, const js::Value &rval);

     /* Monitor an assignment at a SETELEM on a non-integer identifier. */

     static inline void MonitorAssign(JSContext *cx, HandleObject obj, jsid id);

     /* Add a type for a variable in a script. */

     static inline void SetThis(JSContext *cx, JSScript *script, Type type);

     static inline void SetThis(JSContext *cx, JSScript *script, const js::Value &value);

     static inline void SetArgument(JSContext *cx, JSScript *script, unsigned arg, Type type);

     static inline void SetArgument(JSContext *cx, JSScript *script, unsigned arg,

                                    const js::Value &value);

     /*

      * Freeze all the stack type sets in a script, for a compilation. Returns

      * copies of the type sets which will be checked against the actual ones

      * under FinishCompilation, to detect any type changes.

      */

     static bool FreezeTypeSets(CompilerConstraintList *constraints, JSScript *script,

                                TemporaryTypeSet **pThisTypes,

                                TemporaryTypeSet **pArgTypes,

                                TemporaryTypeSet **pBytecodeTypes);

     static void Purge(JSContext *cx, HandleScript script);

     static void Sweep(FreeOp *fop, JSScript *script, bool *oom);

     void destroy();

     size_t sizeOfIncludingThis(mozilla::MallocSizeOf mallocSizeOf) const {

         return mallocSizeOf(this);

     }

 #ifdef DEBUG

     void printTypes(JSContext *cx, HandleScript script) const;

 #endif

 };

 void

 FillBytecodeTypeMap(JSScript *script, uint32_t *bytecodeMap);

 class RecompileInfo;

 // Allocate a CompilerOutput for a finished compilation and generate the type

 // constraints for the compilation. Returns whether the type constraints

 // still hold.

 bool

 FinishCompilation(JSContext *cx, HandleScript script, ExecutionMode executionMode,

                   CompilerConstraintList *constraints, RecompileInfo *precompileInfo);

 // Update the actual types in any scripts queried by constraints with any

 // speculative types added during the definite properties analysis.

 void

 FinishDefinitePropertiesAnalysis(JSContext *cx, CompilerConstraintList *constraints);

 struct ArrayTableKey;

 typedef HashMap<ArrayTableKey,ReadBarriered<TypeObject>,ArrayTableKey,SystemAllocPolicy> ArrayTypeTable;

 struct ObjectTableKey;

 struct ObjectTableEntry;

 typedef HashMap<ObjectTableKey,ObjectTableEntry,ObjectTableKey,SystemAllocPolicy> ObjectTypeTable;

 struct AllocationSiteKey;

 typedef HashMap<AllocationSiteKey,ReadBarriered<TypeObject>,AllocationSiteKey,SystemAllocPolicy> AllocationSiteTable;

 class HeapTypeSetKey;

 // Type set entry for either a JSObject with singleton type or a non-singleton TypeObject.

 struct TypeObjectKey

 {

     static intptr_t keyBits(TypeObjectKey *obj) { return (intptr_t) obj; }

     static TypeObjectKey *getKey(TypeObjectKey *obj) { return obj; }

     static TypeObjectKey *get(JSObject *obj) {

         JS_ASSERT(obj);

         return (TypeObjectKey *) (uintptr_t(obj) | 1);

     }

     static TypeObjectKey *get(TypeObject *obj) {

         JS_ASSERT(obj);

         return (TypeObjectKey *) obj;

     }

     bool isTypeObject() {

         return (uintptr_t(this) & 1) == 0;

     }

     bool isSingleObject() {

         return (uintptr_t(this) & 1) != 0;

     }

     TypeObject *asTypeObject() {

         JS_ASSERT(isTypeObject());

         return (TypeObject *) this;

     }

     JSObject *asSingleObject() {

         JS_ASSERT(isSingleObject());

         return (JSObject *) (uintptr_t(this) & ~1);

     }

     const Class *clasp();

     TaggedProto proto();

     bool hasTenuredProto();

     JSObject *singleton();

     TypeNewScript *newScript();

     bool unknownProperties();

     bool hasFlags(CompilerConstraintList *constraints, TypeObjectFlags flags);

     void watchStateChangeForInlinedCall(CompilerConstraintList *constraints);

     void watchStateChangeForNewScriptTemplate(CompilerConstraintList *constraints);

     void watchStateChangeForTypedArrayData(CompilerConstraintList *constraints);

     HeapTypeSetKey property(jsid id);

     void ensureTrackedProperty(JSContext *cx, jsid id);

     TypeObject *maybeType();

 };

 // Representation of a heap type property which may or may not be instantiated.

 // Heap properties for singleton types are instantiated lazily as they are used

 // by the compiler, but this is only done on the main thread. If we are

 // compiling off thread and use a property which has not yet been instantiated,

 // it will be treated as empty and non-configured and will be instantiated when

 // rejoining to the main thread. If it is in fact not empty, the compilation

 // will fail; to avoid this, we try to instantiate singleton property types

 // during generation of baseline caches.

 class HeapTypeSetKey

 {

     friend class TypeObjectKey;

     // Object and property being accessed.

     TypeObjectKey *object_;

     jsid id_;

     // If instantiated, the underlying heap type set.

     HeapTypeSet *maybeTypes_;

   public:

     HeapTypeSetKey()

       : object_(nullptr), id_(JSID_EMPTY), maybeTypes_(nullptr)

     {}

     TypeObjectKey *object() const { return object_; }

     jsid id() const { return id_; }

     HeapTypeSet *maybeTypes() const { return maybeTypes_; }

     bool instantiate(JSContext *cx);

     void freeze(CompilerConstraintList *constraints);

     jit::MIRType knownMIRType(CompilerConstraintList *constraints);

     bool nonData(CompilerConstraintList *constraints);

     bool nonWritable(CompilerConstraintList *constraints);

     bool isOwnProperty(CompilerConstraintList *constraints);

     bool knownSubset(CompilerConstraintList *constraints, const HeapTypeSetKey &other);

     JSObject *singleton(CompilerConstraintList *constraints);

     bool needsBarrier(CompilerConstraintList *constraints);

 };

 /*

  * Information about the result of the compilation of a script.  This structure

  * stored in the TypeCompartment is indexed by the RecompileInfo. This

  * indirection enables the invalidation of all constraints related to the same

  * compilation.

  */

 class CompilerOutput

 {

     // If this compilation has not been invalidated, the associated script and

     // kind of compilation being performed.

     JSScript *script_;

     ExecutionMode mode_ : 2;

     // Whether this compilation is about to be invalidated.

     bool pendingInvalidation_ : 1;

     // During sweeping, the list of compiler outputs is compacted and invalidated

     // outputs are removed. This gives the new index for a valid compiler output.

     uint32_t sweepIndex_ : 29;

   public:

     static const uint32_t INVALID_SWEEP_INDEX = (1 << 29) - 1;

     CompilerOutput()

       : script_(nullptr), mode_(SequentialExecution),

         pendingInvalidation_(false), sweepIndex_(INVALID_SWEEP_INDEX)

     {}

     CompilerOutput(JSScript *script, ExecutionMode mode)

       : script_(script), mode_(mode),

         pendingInvalidation_(false), sweepIndex_(INVALID_SWEEP_INDEX)

     {}

     JSScript *script() const { return script_; }

     inline ExecutionMode mode() const { return mode_; }

     inline jit::IonScript *ion() const;

     bool isValid() const {

         return script_ != nullptr;

     }

     void invalidate() {

         script_ = nullptr;

     }

     void setPendingInvalidation() {

         pendingInvalidation_ = true;

     }

     bool pendingInvalidation() {

         return pendingInvalidation_;

     }

     void setSweepIndex(uint32_t index) {

         if (index >= INVALID_SWEEP_INDEX)

             MOZ_CRASH();

         sweepIndex_ = index;

     }

     void invalidateSweepIndex() {

         sweepIndex_ = INVALID_SWEEP_INDEX;

     }

     uint32_t sweepIndex() {

         JS_ASSERT(sweepIndex_ != INVALID_SWEEP_INDEX);

         return sweepIndex_;

     }

 };

 class RecompileInfo

 {

     uint32_t outputIndex;

   public:

     RecompileInfo(uint32_t outputIndex = uint32_t(-1))

       : outputIndex(outputIndex)

     {}

     bool operator == (const RecompileInfo &o) const {

         return outputIndex == o.outputIndex;

     }

     CompilerOutput *compilerOutput(TypeZone &types) const;

     CompilerOutput *compilerOutput(JSContext *cx) const;

     bool shouldSweep(TypeZone &types);

 };

 /* Type information for a compartment. */

 struct TypeCompartment

 {

     /* Constraint solving worklist structures. */

     /* Number of scripts in this compartment. */

     unsigned scriptCount;

     /* Table for referencing types of objects keyed to an allocation site. */

     AllocationSiteTable *allocationSiteTable;

     /* Tables for determining types of singleton/JSON objects. */

     ArrayTypeTable *arrayTypeTable;

     ObjectTypeTable *objectTypeTable;

   private:

     void setTypeToHomogenousArray(ExclusiveContext *cx, JSObject *obj, Type type);

   public:

     void fixArrayType(ExclusiveContext *cx, JSObject *obj);

     void fixObjectType(ExclusiveContext *cx, JSObject *obj);

     void fixRestArgumentsType(ExclusiveContext *cx, JSObject *obj);

     JSObject *newTypedObject(JSContext *cx, IdValuePair *properties, size_t nproperties);

     TypeCompartment();

     ~TypeCompartment();

     inline JSCompartment *compartment();

     /* Prints results of this compartment if spew is enabled or force is set. */

     void print(JSContext *cx, bool force);

     /*

      * Make a function or non-function object associated with an optional

      * script. The 'key' parameter here may be an array, typed array, function

      * or JSProto_Object to indicate a type whose class is unknown (not just

      * js_ObjectClass).

      */

     TypeObject *newTypeObject(ExclusiveContext *cx, const Class *clasp, Handle<TaggedProto> proto,

                               TypeObjectFlags initialFlags = 0);

     /* Get or make an object for an allocation site, and add to the allocation site table. */

     TypeObject *addAllocationSiteTypeObject(JSContext *cx, AllocationSiteKey key);

     /* Mark any type set containing obj as having a generic object type. */

     void markSetsUnknown(JSContext *cx, TypeObject *obj);

     void clearTables();

     void sweep(FreeOp *fop);

     void finalizeObjects();

     void addSizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf,

                                 size_t *allocationSiteTables,

                                 size_t *arrayTypeTables,

                                 size_t *objectTypeTables);

 };

 void FixRestArgumentsType(ExclusiveContext *cxArg, JSObject *obj);

 struct TypeZone

 {

     JS::Zone                     *zone_;

     /* Pool for type information in this zone. */

     static const size_t TYPE_LIFO_ALLOC_PRIMARY_CHUNK_SIZE = 8 * 1024;

     js::LifoAlloc                typeLifoAlloc;

     /*

      * All Ion compilations that have occured in this zone, for indexing via

      * RecompileInfo. This includes both valid and invalid compilations, though

      * invalidated compilations are swept on GC.

      */

     Vector<CompilerOutput> *compilerOutputs;

     /* Pending recompilations to perform before execution of JIT code can resume. */

     Vector<RecompileInfo> *pendingRecompiles;

     TypeZone(JS::Zone *zone);

     ~TypeZone();

     JS::Zone *zone() const { return zone_; }

     void sweep(FreeOp *fop, bool releaseTypes, bool *oom);

     void clearAllNewScriptAddendumsOnOOM();

     /* Mark a script as needing recompilation once inference has finished. */

     void addPendingRecompile(JSContext *cx, const RecompileInfo &info);

     void addPendingRecompile(JSContext *cx, JSScript *script);

     void processPendingRecompiles(FreeOp *fop);

 };

 enum SpewChannel {

     ISpewOps,      /* ops: New constraints and types. */

     ISpewResult,   /* result: Final type sets. */

     SPEW_COUNT

 };

 #ifdef DEBUG

 const char * InferSpewColorReset();

 const char * InferSpewColor(TypeConstraint *constraint);

 const char * InferSpewColor(TypeSet *types);

 void InferSpew(SpewChannel which, const char *fmt, ...);

 const char * TypeString(Type type);

 const char * TypeObjectString(TypeObject *type);

 /* Check that the type property for id in obj contains value. */

 bool TypeHasProperty(JSContext *cx, TypeObject *obj, jsid id, const Value &value);

 #else

 inline const char * InferSpewColorReset() { return nullptr; }

 inline const char * InferSpewColor(TypeConstraint *constraint) { return nullptr; }

 inline const char * InferSpewColor(TypeSet *types) { return nullptr; }

 inline void InferSpew(SpewChannel which, const char *fmt, ...) {}

 inline const char * TypeString(Type type) { return nullptr; }

 inline const char * TypeObjectString(TypeObject *type) { return nullptr; }

 #endif

 /* Print a warning, dump state and abort the program. */

 MOZ_NORETURN void TypeFailure(JSContext *cx, const char *fmt, ...);

 } /* namespace types */

 } /* namespace js */

 #endif /* jsinfer_h */