Bumping manifests a=b2g-bump

[gecko.git] / js / src / jsinfer.h

/* -*- 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/UbiNode.h"
#include "js/Utility.h"
#include "js/Vector.h"

namespace js {

class TypeDescr;

class TaggedProto
{
  public:
    static JSObject * const LazyProto;

    TaggedProto() : proto(nullptr) {}
    explicit 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 {
        MOZ_ASSERT(isObject());
        return proto;
    }
    JSObject* toObjectOrNull() const {
        MOZ_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 bool poisoned(const TaggedProto& v) { return IsPoisonedPtr(v.raw()); }
};

template <> struct GCMethods<TaggedProto>
{
    static TaggedProto initial() { return TaggedProto(); }
    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
};

inline const char*
ExecutionModeString(ExecutionMode mode)
{
    switch (mode) {
      case SequentialExecution:
        return "SequentialExecution";
      case ParallelExecution:
        return "ParallelExecution";
      case DefinitePropertiesAnalysis:
        return "DefinitePropertiesAnalysis";
      case ArgumentsUsageAnalysis:
        return "ArgumentsUsageAnalysis";
      default:
        MOZ_CRASH("Invalid ExecutionMode");
    }
}

/*
 * 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 JitAllocPolicy;
    class TempAllocator;
}

namespace types {

struct TypeZone;
class TypeSet;
struct 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;
    explicit 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 {
        MOZ_ASSERT(type < JSVAL_TYPE_OBJECT);
        return (uintptr_t) type == data;
    }

    JSValueType primitive() const {
        MOZ_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 {
        MOZ_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;
    inline JSObject* singleObjectNoBarrier() const;

    /* Accessors for TypeObject types */

    bool isTypeObject() const {
        return isObject() && !(data & 1);
    }

    inline TypeObject* typeObject() const;
    inline TypeObject* typeObjectNoBarrier() 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 SymbolType()    { return Type(JSVAL_TYPE_SYMBOL); }
    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) {
        MOZ_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);

    static js::ThingRootKind rootKind() { return js::THING_ROOT_TYPE; }
};

/* 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 or uninitialized let value. This
 * generally only happens on unconditional type monitors on bailing out of
 * Ion, such as for argument and local types.
 */
inline Type GetMaybeUntrackedValueType(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 changed somehow.
     */
    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_SYMBOL    =  0x40,
    TYPE_FLAG_LAZYARGS  =  0x80,
    TYPE_FLAG_ANYOBJECT = 0x100,

    /* 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 |
                          TYPE_FLAG_SYMBOL,

    /* Mask/shift for the number of objects in objectSet */
    TYPE_FLAG_OBJECT_COUNT_MASK     = 0x3e00,
    TYPE_FLAG_OBJECT_COUNT_SHIFT    = 9,
    TYPE_FLAG_OBJECT_COUNT_LIMIT    = 7,
    TYPE_FLAG_DOMOBJECT_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             = 0x00004000,

    /* Mask of normal type flags on a type set. */
    TYPE_FLAG_BASE_MASK           = 0x000041ff,

    /* 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 = 0x00008000,

    /* Whether the property has ever been made non-writable. */
    TYPE_FLAG_NON_WRITABLE_PROPERTY = 0x00010000,

    /* Whether the property might not be constant. */
    TYPE_FLAG_NON_CONSTANT_PROPERTY = 0x00020000,

    /*
     * 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       = 0xfffc0000,
    TYPE_FLAG_DEFINITE_SHIFT      = 18
};
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, 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         = 0x2,

    /*
     * Whether we have ensured all type sets in the compartment contain
     * ANYOBJECT instead of this object.
     */
    OBJECT_FLAG_SETS_MARKED_UNKNOWN   = 0x4,

    /* Mask/shift for the number of properties in propertySet */
    OBJECT_FLAG_PROPERTY_COUNT_MASK   = 0xfff8,
    OBJECT_FLAG_PROPERTY_COUNT_SHIFT  = 3,
    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,

    /*
     * For a global object, whether any array buffers in this compartment with
     * typed object views have been neutered.
     */
    OBJECT_FLAG_TYPED_OBJECT_NEUTERED = 0x00400000,

    /*
     * Whether objects with this type should be allocated directly in the
     * tenured heap.
     */
    OBJECT_FLAG_PRE_TENURE            = 0x00800000,

    /* Whether objects with this type might have copy on write elements. */
    OBJECT_FLAG_COPY_ON_WRITE         = 0x01000000,

    /*
     * 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    = 0x02000000,

    /* Flags which indicate dynamic properties of represented objects. */
    OBJECT_FLAG_DYNAMIC_MASK          = 0x03ff0000,

    /* Mask for objects created with unknown properties. */
    OBJECT_FLAG_UNKNOWN_MASK =
        OBJECT_FLAG_DYNAMIC_MASK
      | OBJECT_FLAG_SETS_MARKED_UNKNOWN,

    // Mask/shift for the kind of addendum attached to this type object.
    OBJECT_FLAG_ADDENDUM_MASK         = 0x04000000,
    OBJECT_FLAG_ADDENDUM_SHIFT        = 26,

    // Mask/shift for this type object's generation. If out of sync with the
    // TypeZone's generation, this TypeObject hasn't been swept yet.
    OBJECT_FLAG_GENERATION_MASK       = 0x08000000,
    OBJECT_FLAG_GENERATION_SHIFT      = 27,
};
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 {
        MOZ_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 nonConstantProperty() const {
        return flags & TYPE_FLAG_NON_CONSTANT_PROPERTY;
    }
    bool definiteProperty() const { return flags & TYPE_FLAG_DEFINITE_MASK; }
    unsigned definiteSlot() const {
        MOZ_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);
    /* Return the intersection of the 2 TypeSets. The result should not be modified further */
    static TemporaryTypeSet* intersectSets(TemporaryTypeSet* a, TemporaryTypeSet* 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;
    inline JSObject* getSingleObjectNoBarrier(unsigned i) const;
    inline TypeObject* getTypeObjectNoBarrier(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) {
        MOZ_ASSERT(canSetDefinite(slot));
        flags |= ((slot + 1) << TYPE_FLAG_DEFINITE_SHIFT);
        MOZ_ASSERT(definiteSlot() == slot);
    }

    /* Whether any values in this set might have the specified type. */
    bool mightBeMIRType(jit::MIRType type);

    /* Whether all objects have JSCLASS_IS_DOMJSCLASS set. */
    bool isDOMClass();

    /*
     * 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(const TypeSet* other) const;

    /*
     * Get whether the objects in this TypeSet are a subset of the objects
     * in other.
     */
    bool objectsAreSubset(TypeSet* other);

    /* Whether this TypeSet contains exactly the same types as other. */
    bool equals(const TypeSet* other) const {
        return this->isSubset(other) && other->isSubset(this);
    }

    /* 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;
    // Create a new TemporaryTypeSet where the type has been set to object.
    TemporaryTypeSet* cloneObjectsOnly(LifoAlloc* alloc);
    TemporaryTypeSet* cloneWithoutObjects(LifoAlloc* alloc);

    // Trigger a read barrier on all the contents of a type set.
    static void readBarrier(const TypeSet* types);

  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();
};

// If there is an OOM while sweeping types, the type information is deoptimized
// so that it stays correct (i.e. overapproximates the possible types in the
// zone), but constraints might not have been triggered on the deoptimization
// or even copied over completely. In this case, destroy all JIT code and new
// script information in the zone, the only things whose correctness depends on
// the type constraints.
class AutoClearTypeInferenceStateOnOOM
{
    Zone* zone;
    bool oom;

  public:
    explicit AutoClearTypeInferenceStateOnOOM(Zone* zone)
      : zone(zone), oom(false)
    {}

    ~AutoClearTypeInferenceStateOnOOM();

    void setOOM() {
        oom = true;
    }
};

/* 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, AutoClearTypeInferenceStateOnOOM& 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);

    // Mark this type set as being non-constant.
    inline void setNonConstantProperty(ExclusiveContext* cx);
};

class CompilerConstraintList;

CompilerConstraintList*
NewCompilerConstraintList(jit::TempAllocator& alloc);

class TemporaryTypeSet : public TypeSet
{
  public:
    TemporaryTypeSet() {}
    TemporaryTypeSet(LifoAlloc* alloc, 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 Scalar::MaxTypedArrayViewType. */
    Scalar::Type getTypedArrayType();

    /* Get the shared typed array type of all objects in this set, or Scalar::MaxTypedArrayViewType. */
    Scalar::Type getSharedTypedArrayType();

    /* 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;

    explicit 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; }
};

// New script properties analyses overview.
//
// When constructing objects using 'new' on a script, we attempt to determine
// the properties which that object will eventually have. This is done via two
// analyses. One of these, the definite properties analysis, is static, and the
// other, the acquired properties analysis, is dynamic. As objects are
// constructed using 'new' on some script to create objects of type T, our
// analysis strategy is as follows:
//
// - When the first objects are created, no analysis is immediately performed.
//   Instead, all objects of type T are accumulated in an array.
//
// - After a certain number of such objects have been created, the definite
//   properties analysis is performed. This analyzes the body of the
//   constructor script and any other functions it calls to look for properties
//   which will definitely be added by the constructor in a particular order,
//   creating an object with shape S.
//
// - The properties in S are compared with the greatest common prefix P of the
//   shapes of the objects that have been created. If P has more properties
//   than S, the acquired properties analysis is performed.
//
// - The acquired properties analysis marks all properties in P as definite
//   in T, and creates a new type object IT for objects which are partially
//   initialized. Objects of type IT are initially created with shape S, and if
//   they are later given shape P, their type can be changed to T.
//
// For objects which are rarely created, the definite properties analysis can
// be triggered after only one or a few objects have been allocated, when code
// being Ion compiled might access them. In this case type information in the
// constructor might not be good enough for the definite properties analysis to
// compute useful information, but the acquired properties analysis will still
// be able to identify definite properties in this case.
//
// This layered approach is designed to maximize performance on easily
// analyzable code, while still allowing us to determine definite properties
// robustly when code consistently adds the same properties to objects, but in
// complex ways which can't be understood statically.
class TypeNewScript
{
  public:
    struct Initializer {
        enum Kind {
            SETPROP,
            SETPROP_FRAME,
            DONE
        } kind;
        uint32_t offset;
        Initializer(Kind kind, uint32_t offset)
          : kind(kind), offset(offset)
        {}
    };

  private:
    // Scripted function which this information was computed for.
    // If instances of the associated type object are created without calling
    // 'new' on this function, the new script information is cleared.
    RelocatablePtrFunction fun;

    // If fewer than PRELIMINARY_OBJECT_COUNT instances of the type are
    // created, this array holds pointers to each of those objects. When the
    // threshold has been reached, the definite and acquired properties
    // analyses are performed and this array is cleared. The pointers in this
    // array are weak.
    static const uint32_t PRELIMINARY_OBJECT_COUNT = 20;
    PlainObject** preliminaryObjects;

    // After the new script properties analyses have been performed, a template
    // object to use for newly constructed objects. The shape of this object
    // reflects all definite properties the object will have, and the
    // allocation kind to use. Note that this is actually a PlainObject, but is
    // JSObject here to avoid cyclic include dependencies.
    RelocatablePtrPlainObject templateObject_;

    // Order in which definite properties become initialized. We need this in
    // case the definite properties are invalidated (such as by adding a setter
    // to an object on the prototype chain) while an object 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 an incorrect
    // 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.
    Initializer* initializerList;

    // If there are additional properties found by the acquired properties
    // analysis which were not found by the definite properties analysis, this
    // shape contains all such additional properties (plus the definite
    // properties). When an object of this type acquires this shape, it is
    // fully initialized and its type can be changed to initializedType.
    RelocatablePtrShape initializedShape_;

    // Type object with definite properties set for all properties found by
    // both the definite and acquired properties analyses.
    RelocatablePtrTypeObject initializedType_;

  public:
    TypeNewScript() { mozilla::PodZero(this); }
    ~TypeNewScript() {
        js_free(preliminaryObjects);
        js_free(initializerList);
    }

    static inline void writeBarrierPre(TypeNewScript* newScript);

    bool analyzed() const {
        if (preliminaryObjects) {
            MOZ_ASSERT(!templateObject());
            MOZ_ASSERT(!initializerList);
            MOZ_ASSERT(!initializedShape());
            MOZ_ASSERT(!initializedType());
            return false;
        }
        MOZ_ASSERT(templateObject());
        return true;
    }

    PlainObject* templateObject() const {
        return templateObject_;
    }

    Shape* initializedShape() const {
        return initializedShape_;
    }

    TypeObject* initializedType() const {
        return initializedType_;
    }

    void trace(JSTracer* trc);
    void sweep();

#ifdef JSGC_COMPACTING
    void fixupAfterMovingGC();
#endif

    void registerNewObject(PlainObject* res);
    void unregisterNewObject(PlainObject* res);
    bool maybeAnalyze(JSContext* cx, TypeObject* type, bool* regenerate, bool force = false);

    void rollbackPartiallyInitializedObjects(JSContext* cx, TypeObject* type);

    static void make(JSContext* cx, TypeObject* type, JSFunction* fun);
};

/*
 * 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 : public gc::TenuredCell
{
  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) {
        MOZ_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_;

    enum AddendumKind {
        Addendum_NewScript,
        Addendum_TypeDescr
    };

    // If non-null, holds additional information about this object, whose
    // format is indicated by the object's addendum kind.
    void* addendum_;

    void setAddendum(AddendumKind kind, void* addendum);

    AddendumKind addendumKind() const {
        return (AddendumKind)
            ((flags_ & OBJECT_FLAG_ADDENDUM_MASK) >> OBJECT_FLAG_ADDENDUM_SHIFT);
    }

    TypeNewScript* newScriptDontCheckGeneration() const {
        return addendumKind() == Addendum_NewScript
               ? reinterpret_cast<TypeNewScript*>(addendum_)
               : nullptr;
    }

  public:

    TypeObjectFlags flags() {
        maybeSweep(nullptr);
        return flags_;
    }

    void addFlags(TypeObjectFlags flags) {
        maybeSweep(nullptr);
        flags_ |= flags;
    }

    void clearFlags(TypeObjectFlags flags) {
        maybeSweep(nullptr);
        flags_ &= ~flags;
    }

    TypeNewScript* newScript() {
        maybeSweep(nullptr);
        return newScriptDontCheckGeneration();
    }

    void setNewScript(TypeNewScript* newScript) {
        setAddendum(Addendum_NewScript, newScript);
    }

    TypeDescr* maybeTypeDescr() {
        // Note: there is no need to sweep when accessing the type descriptor
        // of an object, as it is strongly held and immutable.
        if (addendumKind() == Addendum_TypeDescr)
            return reinterpret_cast<TypeDescr*>(addendum_);
        return nullptr;
    }

    TypeDescr& typeDescr() {
        MOZ_ASSERT(addendumKind() == Addendum_TypeDescr);
        return *maybeTypeDescr();
    }

    void setTypeDescr(TypeDescr* descr) {
        setAddendum(Addendum_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.
     * In native objects, property types account for plain data properties
     * (those with a slot and no getter or setter hook) and dense elements.
     * In typed objects, property types account for object and value properties
     * and elements in the object.
     *
     * For accesses on these 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 are several exceptions to this:
     *
     * 1. For properties of global JS objects which are undefined at the point
     *    where the property was (lazily) generated, 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.
     *
     * 2. Array lengths are special cased by the compiler and VM and are not
     *    reflected in property types.
     *
     * 3. In typed objects, the initial values of properties (null pointers and
     *    undefined values) are not reflected in the property types. These
     *    values are always possible when reading the property.
     *
     * 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) {
        MOZ_ASSERT((flags & OBJECT_FLAG_DYNAMIC_MASK) == flags);
        return !!(this->flags() & flags);
    }
    bool hasAllFlags(TypeObjectFlags flags) {
        MOZ_ASSERT((flags & OBJECT_FLAG_DYNAMIC_MASK) == flags);
        return (this->flags() & flags) == flags;
    }

    bool unknownProperties() {
        MOZ_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() {
        return !(flags() & OBJECT_FLAG_NURSERY_PROTO);
    }

    gc::InitialHeap initialHeap(CompilerConstraintList* constraints);

    bool canPreTenure() {
        return !unknownProperties();
    }

    bool fromAllocationSite() {
        return flags() & OBJECT_FLAG_FROM_ALLOCATION_SITE;
    }

    void setShouldPreTenure(ExclusiveContext* cx) {
        MOZ_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, Shape* shape);
    bool matchDefiniteProperties(HandleObject obj);
    void addPrototype(JSContext* cx, TypeObject* proto);
    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 maybeClearNewScriptOnOOM();
    void clearNewScript(ExclusiveContext* cx);
    bool isPropertyNonData(jsid id);
    bool isPropertyNonWritable(jsid id);

    void print();

    inline void clearProperties();
    void maybeSweep(AutoClearTypeInferenceStateOnOOM* oom);

  private:
#ifdef DEBUG
    bool needsSweep();
#endif

    uint32_t generation() {
        return (flags_ & OBJECT_FLAG_GENERATION_MASK) >> OBJECT_FLAG_GENERATION_SHIFT;
    }

  public:
    void setGeneration(uint32_t generation) {
        MOZ_ASSERT(generation <= (OBJECT_FLAG_GENERATION_MASK >> OBJECT_FLAG_GENERATION_SHIFT));
        flags_ &= ~OBJECT_FLAG_GENERATION_MASK;
        flags_ |= generation << OBJECT_FLAG_GENERATION_SHIFT;
    }

#ifdef JSGC_COMPACTING
    void fixupAfterMovingGC();
#endif

    size_t sizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf) const;

    inline 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_);
    }

    static inline uint32_t offsetOfAddendum() {
        return offsetof(TypeObject, addendum_);
    }

    static inline uint32_t offsetOfFlags() {
        return offsetof(TypeObject, flags_);
    }

  private:
    inline uint32_t basePropertyCount();
    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 the default
 * types to use for some prototype. An optional associated object is used which
 * allows multiple type objects to be created with the same prototype. The
 * associated object may be a function (for types constructed with 'new') or a
 * type descriptor (for typed objects). These entries are also used for the set
 * of lazy type objects in the compartment, which use a null associated object
 * (though there are only a few of these per compartment).
 */
struct NewTypeObjectEntry
{
    ReadBarrieredTypeObject object;

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

    NewTypeObjectEntry(TypeObject* object, JSObject* associated)
      : object(object), associated(associated)
    {}

    struct Lookup {
        const Class* clasp;
        TaggedProto hashProto;
        TaggedProto matchProto;
        JSObject* associated;

        Lookup(const Class* clasp, TaggedProto proto, JSObject* associated)
          : clasp(clasp), hashProto(proto), matchProto(proto), associated(associated)
        {}

        /*
         * 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, JSObject* associated)
            : clasp(clasp), hashProto(hashProto), matchProto(matchProto), associated(associated)
        {}

    };

    static inline HashNumber hash(const Lookup& lookup);
    static inline bool match(const NewTypeObjectEntry& key, const Lookup& lookup);
    static void rekey(NewTypeObjectEntry& k, const NewTypeObjectEntry& newKey) { k = newKey; }
};
typedef HashSet<NewTypeObjectEntry, NewTypeObjectEntry, SystemAllocPolicy> NewTypeObjectTable;

/* 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 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);

    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);

ArrayObject*
GetOrFixupCopyOnWriteObject(JSContext* cx, HandleScript script, jsbytecode* pc);

ArrayObject*
GetCopyOnWriteObject(JSScript* script, jsbytecode* pc);

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,
                ReadBarrieredTypeObject,
                ArrayTableKey,
                SystemAllocPolicy> ArrayTypeTable;

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

struct AllocationSiteKey;
typedef HashMap<AllocationSiteKey,
                ReadBarrieredTypeObject,
                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) {
        MOZ_ASSERT(obj);
        return (TypeObjectKey*) (uintptr_t(obj) | 1);
    }
    static TypeObjectKey* get(TypeObject* obj) {
        MOZ_ASSERT(obj);
        return (TypeObjectKey*) obj;
    }

    bool isTypeObject() {
        return (uintptr_t(this) & 1) == 0;
    }
    bool isSingleObject() {
        return (uintptr_t(this) & 1) != 0;
    }

    inline TypeObject* asTypeObject();
    inline JSObject* asSingleObject();

    inline TypeObject* asTypeObjectNoBarrier();
    inline JSObject* asSingleObjectNoBarrier();

    const Class* clasp();
    TaggedProto proto();
    bool hasTenuredProto();
    JSObject* singleton();
    TypeNewScript* newScript();

    bool unknownProperties();
    bool hasFlags(CompilerConstraintList* constraints, TypeObjectFlags flags);
    void watchStateChangeForInlinedCall(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 struct 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 allowEmptyTypesForGlobal = false);
    bool knownSubset(CompilerConstraintList* constraints, const HeapTypeSetKey& other);
    JSObject* singleton(CompilerConstraintList* constraints);
    bool needsBarrier(CompilerConstraintList* constraints);
    bool constant(CompilerConstraintList* constraints, Value* valOut);
    bool couldBeConstant(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;
    }
    uint32_t sweepIndex() {
        MOZ_ASSERT(sweepIndex_ != INVALID_SWEEP_INDEX);
        return sweepIndex_;
    }
};

class RecompileInfo
{
    // Index in the TypeZone's compilerOutputs or sweepCompilerOutputs arrays,
    // depending on the generation value.
    uint32_t outputIndex : 31;

    // If out of sync with the TypeZone's generation, this index is for the
    // zone's sweepCompilerOutputs rather than compilerOutputs.
    uint32_t generation : 1;

  public:
    RecompileInfo(uint32_t outputIndex, uint32_t generation)
      : outputIndex(outputIndex), generation(generation)
    {}

    RecompileInfo()
      : outputIndex(JS_BITMASK(31)), generation(0)
    {}

    CompilerOutput* compilerOutput(TypeZone& types) const;
    CompilerOutput* compilerOutput(JSContext* cx) const;
    bool shouldSweep(TypeZone& types);
};

typedef Vector<RecompileInfo, 0, SystemAllocPolicy> RecompileInfoVector;

/* Type information for a compartment. */
struct TypeCompartment
{
    /* 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, ArrayObject* obj);
    void fixObjectType(ExclusiveContext* cx, PlainObject* obj);
    void fixRestArgumentsType(ExclusiveContext* cx, ArrayObject* 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, ArrayObject* obj);

struct AutoEnterAnalysis;

struct TypeZone
{
    JS::Zone* zone_;

    /* Pool for type information in this zone. */
    static const size_t TYPE_LIFO_ALLOC_PRIMARY_CHUNK_SIZE = 8 * 1024;
    LifoAlloc typeLifoAlloc;

    // Current generation for sweeping.
    uint32_t generation : 1;

    /*
     * 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.
     */
    typedef Vector<CompilerOutput, 4, SystemAllocPolicy> CompilerOutputVector;
    CompilerOutputVector* compilerOutputs;

    // During incremental sweeping, allocator holding the old type information
    // for the zone.
    LifoAlloc sweepTypeLifoAlloc;

    // During incremental sweeping, the old compiler outputs for use by
    // recompile indexes with a stale generation.
    CompilerOutputVector* sweepCompilerOutputs;

    // During incremental sweeping, whether to try to destroy all type
    // information attached to scripts.
    bool sweepReleaseTypes;

    // The topmost AutoEnterAnalysis on the stack, if there is one.
    AutoEnterAnalysis* activeAnalysis;

    explicit TypeZone(JS::Zone* zone);
    ~TypeZone();

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

    void beginSweep(FreeOp* fop, bool releaseTypes, AutoClearTypeInferenceStateOnOOM& oom);
    void endSweep(JSRuntime* rt);
    void clearAllNewScriptsOnOOM();

    /* 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, RecompileInfoVector& recompiles);
};

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 */

// JS::ubi::Nodes can point to js::LazyScripts; they're js::gc::Cell instances
// with no associated compartment.
namespace JS {
namespace ubi {
template<> struct Concrete<js::types::TypeObject> : TracerConcrete<js::types::TypeObject> { };
}
}

#endif /* jsinfer_h */