https://github.com/mozilla/gecko-dev
Tip revision: 922e3076b91eda3e2d1be3e61c734b38aa3b3ceb authored by Jeff Walden on 15 March 2014, 08:11:57 UTC
Bug 982974 - Be paranoid when neutering ArrayBuffers. r=sfink, a=1.1.x+
Bug 982974 - Be paranoid when neutering ArrayBuffers. r=sfink, a=1.1.x+
Tip revision: 922e307
jsinfer.h
/* -*- Mode: C++; c-basic-offset: 4; tab-width: 4; indent-tabs-mode: nil -*- */
/* vim: set ts=4 sw=4 et 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/Attributes.h"
#include "jsalloc.h"
#include "jsfriendapi.h"
#include "jsprvtd.h"
#include "ds/LifoAlloc.h"
#include "gc/Barrier.h"
#include "gc/Heap.h"
#include "js/HashTable.h"
#include "js/Vector.h"
namespace JS {
struct TypeInferenceSizes;
}
namespace js {
class TaggedProto
{
public:
TaggedProto() : proto(NULL) {}
TaggedProto(JSObject *proto) : proto(proto) {}
uintptr_t toWord() const { return uintptr_t(proto); }
inline bool isLazy() const;
inline bool isObject() const;
inline JSObject *toObject() const;
inline JSObject *toObjectOrNull() const;
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 RootMethods<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 RootMethods<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;
inline bool isObject() const;
inline JSObject *toObject() const;
inline JSObject *toObjectOrNull() const;
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;
namespace mjit {
struct JITScript;
}
namespace ion {
struct IonScript;
}
namespace types {
/* 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; }
};
/*
* 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 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;
}
inline TypeObjectKey *objectKey() const;
/* Accessors for JSObject types */
bool isSingleObject() const {
return isObject() && !!(data & 1);
}
inline RawObject 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(RawObject 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(JSContext *cx, const Value &val);
/*
* Type inference memory management overview.
*
* Inference constructs a global web of constraints relating the contents of
* type sets particular to various scripts and type objects within a
* compartment. This data can consume a significant amount of memory, and to
* avoid this building up we try to clear it with some regularity.
*
* There are two operations which can clear inference and analysis data.
*
* - Analysis purges clear analysis information while retaining jitcode.
*
* - GCs may clear both analysis information and jitcode. Sometimes GCs will
* preserve all information and code, and will not collect any scripts,
* type objects or singleton JS objects.
*
* There are several categories of data affected differently by the above
* operations.
*
* - Data cleared by every analysis purge and non-preserving GC. This includes
* the ScriptAnalysis for each analyzed script and data from each analysis
* pass performed, type sets for stack values, and all type constraints for
* such type sets and for observed/argument/local type sets on scripts
* (TypeSet::constraintsPurged, aka StackTypeSet). This is exactly the data
* allocated using compartment->analysisLifoAlloc.
*
* - Data cleared by non-preserving GCs. This includes property type sets for
* singleton JS objects, property read input type sets, type constraints on
* all type sets, and dead references in all type sets. This data is all
* allocated using compartment->typeLifoAlloc; the GC copies live data into a
* new allocator and clears the old one.
*
* - Data cleared occasionally by non-preserving GCs. TypeScripts and the data
* in their sets are occasionally destroyed during GC. When a JSScript or
* TypeObject is swept, type information for its contents is destroyed.
*/
/*
* 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(NULL)
{}
/* 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 been configured or received an own property.
*/
virtual void newPropertyState(JSContext *cx, TypeSet *source) {}
/*
* For constraints attached to the JSID_EMPTY type set on an object, mark a
* change in one of the object's dynamic property flags. If force is set,
* recompilation is always triggered.
*/
virtual void newObjectState(JSContext *cx, TypeObject *object, bool force) {}
};
/* Flags and other state stored in TypeSet::flags */
enum {
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/shift for the number of objects in objectSet */
TYPE_FLAG_OBJECT_COUNT_MASK = 0xff00,
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 = 0x00010000,
/* Mask of normal type flags on a type set. */
TYPE_FLAG_BASE_MASK = 0x000100ff,
/* Flags describing the kind of type set this is. */
/*
* Flag for type sets which describe stack values and are cleared on
* analysis purges.
*/
TYPE_FLAG_PURGED = 0x00020000,
/*
* Flag for type sets whose constraints are cleared on analysis purges.
* This includes all temporary type sets, as well as sets in TypeScript
* which propagate into temporary type sets.
*/
TYPE_FLAG_CONSTRAINTS_PURGED = 0x00040000,
/* Flags for type sets which are on object properties. */
/*
* Whether there are subset constraints propagating the possible types
* for this property inherited from the object's prototypes. Reset on GC.
*/
TYPE_FLAG_PROPAGATED_PROPERTY = 0x00080000,
/* Whether this property has ever been directly written. */
TYPE_FLAG_OWN_PROPERTY = 0x00100000,
/*
* Whether the property has ever been deleted or reconfigured to behave
* differently from a normal native property (e.g. made non-writable or
* given a scripted getter or setter).
*/
TYPE_FLAG_CONFIGURED_PROPERTY = 0x00200000,
/*
* Whether the property is definitely in a particular inline slot on all
* objects from which it has not been deleted or reconfigured. Implies
* OWN_PROPERTY and unlike OWN/CONFIGURED property, this cannot change.
*/
TYPE_FLAG_DEFINITE_PROPERTY = 0x00400000,
/* If the property is definite, mask and shift storing the slot. */
TYPE_FLAG_DEFINITE_MASK = 0x0f000000,
TYPE_FLAG_DEFINITE_SHIFT = 24
};
typedef uint32_t TypeFlags;
/* Flags and other state stored in TypeObject::flags */
enum {
/* Objects with this type are functions. */
OBJECT_FLAG_FUNCTION = 0x1,
/* If set, newScript information should not be installed on this object. */
OBJECT_FLAG_NEW_SCRIPT_CLEARED = 0x2,
/*
* If set, type constraints covering the correctness of the newScript
* definite properties need to be regenerated before compiling any jitcode
* which depends on this information.
*/
OBJECT_FLAG_NEW_SCRIPT_REGENERATE = 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,
/*
* Some objects are not dense arrays, or are dense arrays whose length
* property does not fit in an int32_t.
*/
OBJECT_FLAG_NON_DENSE_ARRAY = 0x00010000,
/* Whether any objects this represents are not packed arrays. */
OBJECT_FLAG_NON_PACKED_ARRAY = 0x00020000,
/* Whether any objects this represents are not typed arrays. */
OBJECT_FLAG_NON_TYPED_ARRAY = 0x00040000,
/* Whether any objects this represents are not DOM objects. */
OBJECT_FLAG_NON_DOM = 0x00080000,
/* Whether any represented script is considered uninlineable in JM. */
OBJECT_FLAG_UNINLINEABLE = 0x00100000,
/* Whether any objects have an equality hook. */
OBJECT_FLAG_SPECIAL_EQUALITY = 0x00200000,
/* Whether any objects have been iterated over. */
OBJECT_FLAG_ITERATED = 0x00400000,
/* For a global object, whether flags were set on the RegExpStatics. */
OBJECT_FLAG_REGEXP_FLAGS_SET = 0x00800000,
/* Flags which indicate dynamic properties of represented objects. */
OBJECT_FLAG_DYNAMIC_MASK = 0x00ff0000,
/*
* Whether all properties of this object are considered unknown.
* If set, all flags in DYNAMIC_MASK will also be set.
*/
OBJECT_FLAG_UNKNOWN_PROPERTIES = 0x80000000,
/* Mask for objects created with unknown properties. */
OBJECT_FLAG_UNKNOWN_MASK =
OBJECT_FLAG_DYNAMIC_MASK
| OBJECT_FLAG_UNKNOWN_PROPERTIES
| OBJECT_FLAG_SETS_MARKED_UNKNOWN
};
typedef uint32_t TypeObjectFlags;
class StackTypeSet;
class HeapTypeSet;
/* Information about the set of types associated with an lvalue. */
class TypeSet
{
/* Flags for this type set. */
TypeFlags flags;
/* Possible objects this type set can represent. */
TypeObjectKey **objectSet;
public:
/* Chain of constraints which propagate changes out from this type set. */
TypeConstraint *constraintList;
TypeSet()
: flags(0), objectSet(NULL), constraintList(NULL)
{}
void print();
inline void sweep(JSCompartment *compartment);
inline size_t computedSizeOfExcludingThis();
/* Whether this set contains a specific type. */
inline bool hasType(Type type);
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 ownProperty(bool configurable) const {
return flags & (configurable ? TYPE_FLAG_CONFIGURED_PROPERTY : TYPE_FLAG_OWN_PROPERTY);
}
bool definiteProperty() const { return flags & TYPE_FLAG_DEFINITE_PROPERTY; }
unsigned definiteSlot() const {
JS_ASSERT(definiteProperty());
return flags >> TYPE_FLAG_DEFINITE_SHIFT;
}
/*
* Add a type to this set, calling any constraint handlers if this is a new
* possible type.
*/
inline void addType(JSContext *cx, Type type);
/* Mark this type set as representing an own property or configured property. */
inline void setOwnProperty(JSContext *cx, bool configured);
/*
* Iterate through the objects in this set. getObjectCount overapproximates
* in the hash case (see SET_ARRAY_SIZE in jsinferinlines.h), and getObject
* may return NULL.
*/
inline unsigned getObjectCount();
inline TypeObjectKey *getObject(unsigned i);
inline RawObject getSingleObject(unsigned i);
inline TypeObject *getTypeObject(unsigned i);
void setOwnProperty(bool configurable) {
flags |= TYPE_FLAG_OWN_PROPERTY;
if (configurable)
flags |= TYPE_FLAG_CONFIGURED_PROPERTY;
}
void setDefinite(unsigned slot) {
JS_ASSERT(slot <= (TYPE_FLAG_DEFINITE_MASK >> TYPE_FLAG_DEFINITE_SHIFT));
flags |= TYPE_FLAG_DEFINITE_PROPERTY | (slot << TYPE_FLAG_DEFINITE_SHIFT);
}
bool hasPropagatedProperty() { return !!(flags & TYPE_FLAG_PROPAGATED_PROPERTY); }
void setPropagatedProperty() { flags |= TYPE_FLAG_PROPAGATED_PROPERTY; }
bool constraintsPurged() { return !!(flags & TYPE_FLAG_CONSTRAINTS_PURGED); }
void setConstraintsPurged() { flags |= TYPE_FLAG_CONSTRAINTS_PURGED; }
bool purged() { return !!(flags & TYPE_FLAG_PURGED); }
void setPurged() { flags |= TYPE_FLAG_PURGED | TYPE_FLAG_CONSTRAINTS_PURGED; }
inline StackTypeSet *toStackTypeSet();
inline HeapTypeSet *toHeapTypeSet();
inline void addTypesToConstraint(JSContext *cx, TypeConstraint *constraint);
inline void add(JSContext *cx, TypeConstraint *constraint, bool callExisting = true);
protected:
uint32_t baseObjectCount() const {
return (flags & TYPE_FLAG_OBJECT_COUNT_MASK) >> TYPE_FLAG_OBJECT_COUNT_SHIFT;
}
inline void setBaseObjectCount(uint32_t count);
inline void clearObjects();
};
/*
* Type set for a stack value manipulated in a script, or the argument or
* local types of said script. Constraints on these type sets are cleared
* during analysis purges; the contents of the sets are implicitly frozen
* during compilation to ensure that changes to the sets trigger recompilation
* of the associated script.
*/
class StackTypeSet : public TypeSet
{
public:
/*
* Make a type set with the specified debugging name, not embedded in
* another structure.
*/
static StackTypeSet *make(JSContext *cx, const char *name);
/* Constraints for type inference. */
void addSubset(JSContext *cx, TypeSet *target);
void addGetProperty(JSContext *cx, HandleScript script, jsbytecode *pc,
StackTypeSet *target, jsid id);
void addSetProperty(JSContext *cx, HandleScript script, jsbytecode *pc,
StackTypeSet *target, jsid id);
void addSetElement(JSContext *cx, HandleScript script, jsbytecode *pc,
StackTypeSet *objectTypes, StackTypeSet *valueTypes);
void addCall(JSContext *cx, TypeCallsite *site);
void addArith(JSContext *cx, HandleScript script, jsbytecode *pc,
TypeSet *target, TypeSet *other = NULL);
void addTransformThis(JSContext *cx, HandleScript script, TypeSet *target);
void addPropagateThis(JSContext *cx, HandleScript script, jsbytecode *pc,
Type type, StackTypeSet *types = NULL);
void addSubsetBarrier(JSContext *cx, HandleScript script, jsbytecode *pc, TypeSet *target);
/*
* 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. */
JSValueType getKnownTypeTag();
bool isMagicArguments() { return getKnownTypeTag() == JSVAL_TYPE_MAGIC; }
/* 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(JSContext *cx, TypeObjectFlags flags);
/*
* Get the typed array type of all objects in this set. Returns
* TypedArray::TYPE_MAX if the set contains different array types.
*/
int getTypedArrayType();
/* Get the single value which can appear in this type set, otherwise NULL. */
RawObject getSingleton();
/* Whether any objects in the type set needs a barrier on id. */
bool propertyNeedsBarrier(JSContext *cx, jsid id);
/*
* Get whether this type only contains non-string primitives:
* null/undefined/int/double, or some combination of those.
*/
bool knownNonStringPrimitive();
};
/*
* Type set for a property of a TypeObject, or for the return value or property
* read inputs of a script. In contrast with stack type sets, constraints on
* these sets are not cleared during analysis purges, and are not implicitly
* frozen during compilation.
*/
class HeapTypeSet : public TypeSet
{
public:
/* Constraints for type inference. */
void addSubset(JSContext *cx, TypeSet *target);
void addGetProperty(JSContext *cx, HandleScript script, jsbytecode *pc,
StackTypeSet *target, jsid id);
void addCallProperty(JSContext *cx, HandleScript script, jsbytecode *pc, jsid id);
void addFilterPrimitives(JSContext *cx, TypeSet *target);
void addSubsetBarrier(JSContext *cx, HandleScript script, jsbytecode *pc, TypeSet *target);
/* Constraints for JIT compilation. */
/* Completely freeze the contents of this type set. */
void addFreeze(JSContext *cx);
/*
* Watch for a generic object state change on a type object. This currently
* includes reallocations of slot pointers for global objects, and changes
* to newScript data on types.
*/
static void WatchObjectStateChange(JSContext *cx, TypeObject *object);
/* Whether an object has any of a set of flags. */
static bool HasObjectFlags(JSContext *cx, TypeObject *object, TypeObjectFlags flags);
/*
* For type sets on a property, return true if the property has any 'own'
* values assigned. If configurable is set, return 'true' if the property
* has additionally been reconfigured as non-configurable, non-enumerable
* or non-writable (this only applies to properties that have changed after
* having been created, not to e.g. properties non-writable on creation).
*/
bool isOwnProperty(JSContext *cx, TypeObject *object, bool configurable);
/* Get whether this type set is non-empty. */
bool knownNonEmpty(JSContext *cx);
/* Get whether this type set is known to be a subset of other. */
bool knownSubset(JSContext *cx, TypeSet *other);
/* Get the single value which can appear in this type set, otherwise NULL. */
RawObject getSingleton(JSContext *cx);
/*
* Whether a location with this TypeSet needs a write barrier (i.e., whether
* it can hold GC things). The type set is frozen if no barrier is needed.
*/
bool needsBarrier(JSContext *cx);
/* Get any type tag which all values in this set must have. */
JSValueType getKnownTypeTag(JSContext *cx);
};
inline StackTypeSet *
TypeSet::toStackTypeSet()
{
JS_ASSERT(constraintsPurged());
return (StackTypeSet *) this;
}
inline HeapTypeSet *
TypeSet::toHeapTypeSet()
{
JS_ASSERT(!constraintsPurged());
return (HeapTypeSet *) this;
}
/*
* Handler which persists information about dynamic types pushed within a
* script which can affect its behavior and are not covered by JOF_TYPESET ops,
* such as integer operations which overflow to a double. These persist across
* GCs, and are used to re-seed script types when they are reanalyzed.
*/
struct TypeResult
{
uint32_t offset;
Type type;
TypeResult *next;
TypeResult(uint32_t offset, Type type)
: offset(offset), type(type), next(NULL)
{}
};
/* Is this a reasonable PC to be doing inlining on? */
inline bool isInlinableCall(jsbytecode *pc);
/*
* Type barriers overview.
*
* Type barriers are a technique for using dynamic type information to improve
* the inferred types within scripts. At certain opcodes --- those with the
* JOF_TYPESET format --- we will construct a type set storing the set of types
* which we have observed to be pushed at that opcode, and will only use those
* observed types when doing propagation downstream from the bytecode. For
* example, in the following script:
*
* function foo(x) {
* return x.f + 10;
* }
*
* Suppose we know the type of 'x' and that the type of its 'f' property is
* either an int or float. To account for all possible behaviors statically,
* we would mark the result of the 'x.f' access as an int or float, as well
* as the result of the addition and the return value of foo (and everywhere
* the result of 'foo' is used). When dealing with polymorphic code, this is
* undesirable behavior --- the type imprecision surrounding the polymorphism
* will tend to leak to many places in the program.
*
* Instead, we will keep track of the types that have been dynamically observed
* to have been produced by the 'x.f', and only use those observed types
* downstream from the access. If the 'x.f' has only ever produced integers,
* we will treat its result as an integer and mark the result of foo as an
* integer.
*
* The set of observed types will be a subset of the set of possible types,
* and if the two sets are different, a type barriers will be added at the
* bytecode which checks the dynamic result every time the bytecode executes
* and makes sure it is in the set of observed types. If it is not, that
* observed set is updated, and the new type information is automatically
* propagated along the already-generated type constraints to the places
* where the result of the bytecode is used.
*
* Observing new types at a bytecode removes type barriers at the bytecode
* (this removal happens lazily, see ScriptAnalysis::pruneTypeBarriers), and if
* all type barriers at a bytecode are removed --- the set of observed types
* grows to match the set of possible types --- then the result of the bytecode
* no longer needs to be dynamically checked (unless the set of possible types
* grows, triggering the generation of new type barriers).
*
* Barriers are only relevant for accesses on properties whose types inference
* actually tracks (see propertySet comment under TypeObject). Accesses on
* other properties may be able to produce additional unobserved types even
* without a barrier present, and can only be compiled to jitcode with special
* knowledge of the property in question (e.g. for lengths of arrays, or
* elements of typed arrays).
*/
/*
* Barrier introduced at some bytecode. These are added when, during inference,
* we block a type from being propagated as would normally be done for a subset
* constraint. The propagation is technically possible, but we suspect it will
* not happen dynamically and this type needs to be watched for. These are only
* added at reads of properties and at scripted call sites.
*/
struct TypeBarrier
{
/* Next barrier on the same bytecode. */
TypeBarrier *next;
/* Target type set into which propagation was blocked. */
TypeSet *target;
/*
* Type which was not added to the target. If target ends up containing the
* type somehow, this barrier can be removed.
*/
Type type;
/*
* If specified, this barrier can be removed if object has a non-undefined
* value in property id.
*/
JSObject *singleton;
jsid singletonId;
TypeBarrier(TypeSet *target, Type type, JSObject *singleton, jsid singletonId)
: next(NULL), target(target), type(type),
singleton(singleton), singletonId(singletonId)
{}
};
/* 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;
inline Property(jsid id);
inline Property(const Property &o);
static uint32_t keyBits(jsid id) { return uint32_t(JSID_BITS(id)); }
static jsid getKey(Property *p) { return p->id; }
};
/*
* 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
{
HeapPtrFunction fun;
/* Allocation kind to use for newly constructed objects. */
gc::AllocKind allocKind;
/*
* Shape to use for newly constructed objects. Reflects all definite
* properties the object will have.
*/
HeapPtrShape shape;
/*
* 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. Initialization can traverse stack frames,
* in which case FRAME_PUSH/FRAME_POP are used.
*/
struct Initializer {
enum Kind {
SETPROP,
FRAME_PUSH,
FRAME_POP,
DONE
} kind;
uint32_t offset;
Initializer(Kind kind, uint32_t offset)
: kind(kind), offset(offset)
{}
};
Initializer *initializerList;
static inline void writeBarrierPre(TypeNewScript *newScript);
static inline void writeBarrierPost(TypeNewScript *newScript, void *addr);
};
/*
* 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.
*
* When a GC occurs, we wipe out all analysis information for all the
* compartment's scripts, so can destroy all properties on singleton type
* objects at the same time. If there is no reference on the stack to the
* type object itself, the type object is also destroyed, and the JS object
* reverts to having a lazy type.
*/
/* Type information about an object accessed by a script. */
struct TypeObject : gc::Cell
{
/* 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;
/*
* 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 == (RawObject) LAZY_SINGLETON; }
/* Flags for this object. */
TypeObjectFlags flags;
/*
* Estimate of the contribution of this object to the type sets it appears in.
* This is the sum of the sizes of those sets at the point when the object
* was added.
*
* When the contribution exceeds the CONTRIBUTION_LIMIT, any type sets the
* object is added to are instead marked as unknown. If we get to this point
* we are probably not adding types which will let us do meaningful optimization
* later, and we want to ensure in such cases that our time/space complexity
* is linear, not worst-case cubic as it would otherwise be.
*/
uint32_t contribution;
static const uint32_t CONTRIBUTION_LIMIT = 2000;
/*
* If non-NULL, 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<TypeNewScript> newScript;
/*
* 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 singleton 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.
*
* We establish these by using write barriers on calls to setProperty and
* defineProperty which are on native properties, and by using the inference
* analysis to determine the side effects of code which is JIT-compiled.
*/
Property **propertySet;
/* If this is an interpreted function, the function object. */
HeapPtrFunction interpretedFunction;
#if JS_BITS_PER_WORD == 32
void *padding;
#endif
inline TypeObject(TaggedProto proto, bool isFunction, bool unknown);
bool isFunction() { return !!(flags & OBJECT_FLAG_FUNCTION); }
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);
}
/*
* Get or create a property of this object. Only call this for properties which
* a script accesses explicitly. 'assign' indicates whether this is for an
* assignment, and the own types of the property will be used instead of
* aggregate types.
*/
inline HeapTypeSet *getProperty(JSContext *cx, jsid id, bool own);
/* Get a property only if it already exists. */
inline HeapTypeSet *maybeGetProperty(JSContext *cx, jsid id);
inline unsigned getPropertyCount();
inline Property *getProperty(unsigned i);
/* Set flags on this object which are implied by the specified key. */
inline void setFlagsFromKey(JSContext *cx, JSProtoKey kind);
/*
* Get the global object which all objects of this type are parented to,
* or NULL if there is none known.
*/
//inline JSObject *getGlobal();
/* Helpers */
bool addProperty(JSContext *cx, jsid id, Property **pprop);
bool addDefiniteProperties(JSContext *cx, HandleObject obj);
bool matchDefiniteProperties(HandleObject obj);
void addPrototype(JSContext *cx, TypeObject *proto);
void addPropertyType(JSContext *cx, jsid id, Type type);
void addPropertyType(JSContext *cx, jsid id, const Value &value);
void addPropertyType(JSContext *cx, const char *name, Type type);
void addPropertyType(JSContext *cx, const char *name, const Value &value);
void markPropertyConfigured(JSContext *cx, jsid id);
void markStateChange(JSContext *cx);
void setFlags(JSContext *cx, TypeObjectFlags flags);
void markUnknown(JSContext *cx);
void clearNewScript(JSContext *cx);
void getFromPrototypes(JSContext *cx, jsid id, TypeSet *types, bool force = false);
void print();
inline void clearProperties();
inline void sweep(FreeOp *fop);
inline size_t computedSizeOfExcludingThis();
void sizeOfExcludingThis(TypeInferenceSizes *sizes, JSMallocSizeOfFun mallocSizeOf);
/*
* 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 void writeBarrierPre(TypeObject *type);
static inline void writeBarrierPost(TypeObject *type, void *addr);
static inline void readBarrier(TypeObject *type);
static inline ThingRootKind rootKind() { return THING_ROOT_TYPE_OBJECT; }
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 the default
* 'new' or the lazy types of some prototype.
*/
struct TypeObjectEntry
{
typedef TaggedProto Lookup;
static inline HashNumber hash(TaggedProto base);
static inline bool match(TypeObject *key, TaggedProto lookup);
};
typedef HashSet<ReadBarriered<TypeObject>, TypeObjectEntry, SystemAllocPolicy> TypeObjectSet;
/* Whether to use a new type object when calling 'new' at script/pc. */
bool
UseNewType(JSContext *cx, HandleScript script, jsbytecode *pc);
/* Whether to use a new type object for an initializer opcode at script/pc. */
bool
UseNewTypeForInitializer(JSContext *cx, HandleScript script, jsbytecode *pc, JSProtoKey key);
/*
* Whether Array.prototype, or an object on its proto chain, has an
* indexed property.
*/
bool
ArrayPrototypeHasIndexedProperty(JSContext *cx, HandleScript script);
/*
* Type information about a callsite. this is separated from the bytecode
* information itself so we can handle higher order functions not called
* directly via a bytecode.
*/
struct TypeCallsite
{
JSScript *script;
jsbytecode *pc;
/* Whether this is a 'NEW' call. */
bool isNew;
/* Types of each argument to the call. */
unsigned argumentCount;
StackTypeSet **argumentTypes;
/* Types of the this variable. */
StackTypeSet *thisTypes;
/* Type set receiving the return value of this call. */
StackTypeSet *returnTypes;
inline TypeCallsite(JSContext *cx, JSScript *script, jsbytecode *pc,
bool isNew, unsigned argumentCount);
};
/* Persistent type information for a script, retained across GCs. */
class TypeScript
{
friend struct ::JSScript;
/* Analysis information for the script, cleared on each GC. */
analyze::ScriptAnalysis *analysis;
public:
/* Dynamic types generated at points within this script. */
TypeResult *dynamicList;
/*
* Array of type sets storing the possible inputs to property reads.
* Generated the first time the script is analyzed by inference and kept
* after analysis purges.
*/
HeapTypeSet *propertyReadTypes;
/* Array of type type sets for variables and JOF_TYPESET ops. */
TypeSet *typeArray() { return (TypeSet *) (uintptr_t(this) + sizeof(TypeScript)); }
static inline unsigned NumTypeSets(RawScript script);
static inline HeapTypeSet *ReturnTypes(RawScript script);
static inline StackTypeSet *ThisTypes(RawScript script);
static inline StackTypeSet *ArgTypes(RawScript script, unsigned i);
static inline StackTypeSet *LocalTypes(RawScript script, unsigned i);
/* Follows slot layout in jsanalyze.h, can get this/arg/local type sets. */
static inline StackTypeSet *SlotTypes(RawScript script, unsigned slot);
#ifdef DEBUG
/* Check that correct types were inferred for the values pushed by this bytecode. */
static void CheckBytecode(JSContext *cx, HandleScript script, jsbytecode *pc,
const js::Value *sp);
#endif
/* Get the default 'new' object for a given standard class, per the script's global. */
static inline TypeObject *StandardType(JSContext *cx, HandleScript script, JSProtoKey kind);
/* Get a type object for an allocation site in this script. */
static inline TypeObject *InitObject(JSContext *cx, HandleScript script, jsbytecode *pc,
JSProtoKey kind);
/*
* Monitor a bytecode pushing a value which is not accounted for by the
* inference type constraints, such as integer overflow.
*/
static inline void MonitorOverflow(JSContext *cx, HandleScript script, jsbytecode *pc);
static inline void MonitorString(JSContext *cx, HandleScript script, jsbytecode *pc);
static inline void MonitorUnknown(JSContext *cx, HandleScript script, jsbytecode *pc);
static inline void GetPcScript(JSContext *cx, MutableHandleScript script, jsbytecode **pc);
static inline void MonitorOverflow(JSContext *cx);
static inline void MonitorString(JSContext *cx);
static inline void MonitorUnknown(JSContext *cx);
/*
* 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, HandleScript 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, HandleScript script, Type type);
static inline void SetThis(JSContext *cx, HandleScript script, const js::Value &value);
static inline void SetLocal(JSContext *cx, HandleScript script, unsigned local, Type type);
static inline void SetLocal(JSContext *cx, HandleScript script, unsigned local,
const js::Value &value);
static inline void SetArgument(JSContext *cx, HandleScript script, unsigned arg, Type type);
static inline void SetArgument(JSContext *cx, HandleScript script, unsigned arg,
const js::Value &value);
static void AddFreezeConstraints(JSContext *cx, HandleScript script);
static void Purge(JSContext *cx, HandleScript script);
static void Sweep(FreeOp *fop, RawScript script);
void destroy();
};
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;
/*
* Information about the result of the compilation of a script. This structure
* stored in the TypeCompartment is indexed by the RecompileInfo. This
* indirection enable the invalidation of all constraints related to the same
* compilation. The compiler output is build by the AutoEnterCompilation.
*/
struct CompilerOutput
{
JSScript *script;
bool isIonFlag : 1;
bool constructing : 1;
bool barriers : 1;
bool pendingRecompilation : 1;
uint32_t chunkIndex:28;
CompilerOutput();
bool isJM() const { return !isIonFlag; }
bool isIon() const { return isIonFlag; }
mjit::JITScript *mjit() const;
ion::IonScript *ion() const;
bool isValid() const;
void setPendingRecompilation() {
pendingRecompilation = true;
}
void invalidate() {
script = NULL;
}
};
struct RecompileInfo
{
static const uint32_t NoCompilerRunning = uint32_t(-1);
uint32_t outputIndex;
RecompileInfo()
: outputIndex(NoCompilerRunning)
{
}
bool operator == (const RecompileInfo &o) const {
return outputIndex == o.outputIndex;
}
CompilerOutput *compilerOutput(TypeCompartment &types) const;
CompilerOutput *compilerOutput(JSContext *cx) const;
};
/* Type information for a compartment. */
struct TypeCompartment
{
/* Constraint solving worklist structures. */
/*
* Worklist of types which need to be propagated to constraints. We use a
* worklist to avoid blowing the native stack.
*/
struct PendingWork
{
TypeConstraint *constraint;
TypeSet *source;
Type type;
};
PendingWork *pendingArray;
unsigned pendingCount;
unsigned pendingCapacity;
/* Whether we are currently resolving the pending worklist. */
bool resolving;
/* Whether type inference is enabled in this compartment. */
bool inferenceEnabled;
/*
* Bit set if all current types must be marked as unknown, and all scripts
* recompiled. Caused by OOM failure within inference operations.
*/
bool pendingNukeTypes;
/* Number of scripts in this compartment. */
unsigned scriptCount;
/* Valid & Invalid script referenced by type constraints. */
Vector<CompilerOutput> *constrainedOutputs;
/* Pending recompilations to perform before execution of JIT code can resume. */
Vector<RecompileInfo> *pendingRecompiles;
/*
* Number of recompilation events and inline frame expansions that have
* occurred in this compartment. If these change, code should not count on
* compiled code or the current stack being intact.
*/
unsigned recompilations;
unsigned frameExpansions;
/*
* Script currently being compiled. All constraints which look for type
* changes inducing recompilation are keyed to this script. Note: script
* compilation is not reentrant.
*/
RecompileInfo compiledInfo;
/* 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;
void fixArrayType(JSContext *cx, HandleObject obj);
void fixObjectType(JSContext *cx, HandleObject obj);
/* Logging fields */
/* Counts of stack type sets with some number of possible operand types. */
static const unsigned TYPE_COUNT_LIMIT = 4;
unsigned typeCounts[TYPE_COUNT_LIMIT];
unsigned typeCountOver;
void init(JSContext *cx);
~TypeCompartment();
inline JSCompartment *compartment();
/* Add a type to register with a list of constraints. */
inline void addPending(JSContext *cx, TypeConstraint *constraint, TypeSet *source, Type type);
bool growPendingArray(JSContext *cx);
/* Resolve pending type registrations, excluding delayed ones. */
inline void resolvePending(JSContext *cx);
/* 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(JSContext *cx, JSProtoKey kind, Handle<TaggedProto> proto,
bool unknown = false, bool isDOM = false);
/* Get or make an object for an allocation site, and add to the allocation site table. */
TypeObject *addAllocationSiteTypeObject(JSContext *cx, AllocationSiteKey key);
void nukeTypes(FreeOp *fop);
void processPendingRecompiles(FreeOp *fop);
/* Mark all types as needing destruction once inference has 'finished'. */
void setPendingNukeTypes(JSContext *cx);
void setPendingNukeTypesNoReport();
/* Mark a script as needing recompilation once inference has finished. */
void addPendingRecompile(JSContext *cx, const RecompileInfo &info);
void addPendingRecompile(JSContext *cx, HandleScript script, jsbytecode *pc);
/* Monitor future effects on a bytecode. */
void monitorBytecode(JSContext *cx, HandleScript script, uint32_t offset,
bool returnOnly = false);
/* Mark any type set containing obj as having a generic object type. */
void markSetsUnknown(JSContext *cx, TypeObject *obj);
void sweep(FreeOp *fop);
void sweepCompilerOutputs(FreeOp *fop, bool discardConstraints);
void maybePurgeAnalysis(JSContext *cx, bool force = false);
void finalizeObjects();
};
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 NULL; }
inline const char * InferSpewColor(TypeConstraint *constraint) { return NULL; }
inline const char * InferSpewColor(TypeSet *types) { return NULL; }
inline void InferSpew(SpewChannel which, const char *fmt, ...) {}
inline const char * TypeString(Type type) { return NULL; }
inline const char * TypeObjectString(TypeObject *type) { return NULL; }
#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___
