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/*
* Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
* Copyright (C) 2001 Peter Kelly (pmk@post.com)
* Copyright (C) 2003-2019 Apple Inc. All rights reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#pragma once
#include "JSExportMacros.h"
#include "PureNaN.h"
#include <functional>
#include <math.h>
#include <stddef.h>
#include <stdint.h>
#include <wtf/Assertions.h>
#include <wtf/Forward.h>
#include <wtf/HashMap.h>
#include <wtf/HashTraits.h>
#include <wtf/MathExtras.h>
#include <wtf/MediaTime.h>
#include <wtf/StdLibExtras.h>
#include <wtf/TriState.h>
namespace JSC {
class AssemblyHelpers;
class JSBigInt;
class ExecState;
class JSCell;
class JSValueSource;
class VM;
class JSGlobalObject;
class JSObject;
class JSString;
class Identifier;
class PropertyName;
class PropertySlot;
class PutPropertySlot;
class Structure;
#if ENABLE(DFG_JIT)
namespace DFG {
class JITCompiler;
class OSRExitCompiler;
class SpeculativeJIT;
}
#endif
#if ENABLE(C_LOOP)
namespace LLInt {
class CLoop;
}
#endif
struct ClassInfo;
struct DumpContext;
struct Instruction;
struct MethodTable;
enum class Unknown { };
template <class T, typename Traits> class WriteBarrierBase;
template<class T>
using WriteBarrierTraitsSelect = typename std::conditional<std::is_same<T, Unknown>::value,
DumbValueTraits<T>, DumbPtrTraits<T>
>::type;
enum PreferredPrimitiveType { NoPreference, PreferNumber, PreferString };
enum ECMAMode { StrictMode, NotStrictMode };
enum class CallType : unsigned;
struct CallData;
enum class ConstructType : unsigned;
struct ConstructData;
typedef int64_t EncodedJSValue;
union EncodedValueDescriptor {
int64_t asInt64;
#if USE(JSVALUE32_64)
double asDouble;
#elif USE(JSVALUE64)
JSCell* ptr;
#endif
#if CPU(BIG_ENDIAN)
struct {
int32_t tag;
int32_t payload;
} asBits;
#else
struct {
int32_t payload;
int32_t tag;
} asBits;
#endif
};
#define TagOffset (offsetof(EncodedValueDescriptor, asBits.tag))
#define PayloadOffset (offsetof(EncodedValueDescriptor, asBits.payload))
#if USE(JSVALUE64)
#define CellPayloadOffset 0
#else
#define CellPayloadOffset PayloadOffset
#endif
enum WhichValueWord {
TagWord,
PayloadWord
};
int64_t tryConvertToInt52(double);
bool isInt52(double);
enum class SourceCodeRepresentation : uint8_t {
Other,
Integer,
Double
};
class JSValue {
friend struct EncodedJSValueHashTraits;
friend struct EncodedJSValueWithRepresentationHashTraits;
friend class AssemblyHelpers;
friend class JIT;
friend class JITSlowPathCall;
friend class JITStubs;
friend class JITStubCall;
friend class JSInterfaceJIT;
friend class JSValueSource;
friend class SpecializedThunkJIT;
#if ENABLE(DFG_JIT)
friend class DFG::JITCompiler;
friend class DFG::OSRExitCompiler;
friend class DFG::SpeculativeJIT;
#endif
#if ENABLE(C_LOOP)
friend class LLInt::CLoop;
#endif
public:
#if USE(JSVALUE32_64)
enum { Int32Tag = 0xffffffff };
enum { BooleanTag = 0xfffffffe };
enum { NullTag = 0xfffffffd };
enum { UndefinedTag = 0xfffffffc };
enum { CellTag = 0xfffffffb };
enum { EmptyValueTag = 0xfffffffa };
enum { DeletedValueTag = 0xfffffff9 };
enum { LowestTag = DeletedValueTag };
#endif
static EncodedJSValue encode(JSValue);
static JSValue decode(EncodedJSValue);
enum JSNullTag { JSNull };
enum JSUndefinedTag { JSUndefined };
enum JSTrueTag { JSTrue };
enum JSFalseTag { JSFalse };
enum JSCellTag { JSCellType };
enum EncodeAsDoubleTag { EncodeAsDouble };
JSValue();
JSValue(JSNullTag);
JSValue(JSUndefinedTag);
JSValue(JSTrueTag);
JSValue(JSFalseTag);
JSValue(JSCell* ptr);
JSValue(const JSCell* ptr);
// Numbers
JSValue(EncodeAsDoubleTag, double);
explicit JSValue(double);
explicit JSValue(char);
explicit JSValue(unsigned char);
explicit JSValue(short);
explicit JSValue(unsigned short);
explicit JSValue(int);
explicit JSValue(unsigned);
explicit JSValue(long);
explicit JSValue(unsigned long);
explicit JSValue(long long);
explicit JSValue(unsigned long long);
explicit operator bool() const;
bool operator==(const JSValue& other) const;
bool operator!=(const JSValue& other) const;
bool isInt32() const;
bool isUInt32() const;
bool isDouble() const;
bool isTrue() const;
bool isFalse() const;
int32_t asInt32() const;
uint32_t asUInt32() const;
int64_t asAnyInt() const;
uint32_t asUInt32AsAnyInt() const;
int32_t asInt32AsAnyInt() const;
double asDouble() const;
bool asBoolean() const;
double asNumber() const;
int32_t asInt32ForArithmetic() const; // Boolean becomes an int, but otherwise like asInt32().
// Querying the type.
bool isEmpty() const;
bool isFunction(VM&) const;
bool isCallable(VM&, CallType&, CallData&) const;
bool isConstructor(VM&) const;
bool isConstructor(VM&, ConstructType&, ConstructData&) const;
bool isUndefined() const;
bool isNull() const;
bool isUndefinedOrNull() const;
bool isBoolean() const;
bool isAnyInt() const;
bool isUInt32AsAnyInt() const;
bool isInt32AsAnyInt() const;
bool isNumber() const;
bool isString() const;
bool isBigInt() const;
bool isSymbol() const;
bool isPrimitive() const;
bool isGetterSetter() const;
bool isCustomGetterSetter() const;
bool isObject() const;
bool inherits(VM&, const ClassInfo*) const;
template<typename Target> bool inherits(VM&) const;
const ClassInfo* classInfoOrNull(VM&) const;
// Extracting the value.
bool getString(ExecState*, WTF::String&) const;
WTF::String getString(ExecState*) const; // null string if not a string
JSObject* getObject() const; // 0 if not an object
// Extracting integer values.
bool getUInt32(uint32_t&) const;
// Basic conversions.
JSValue toPrimitive(ExecState*, PreferredPrimitiveType = NoPreference) const;
bool getPrimitiveNumber(ExecState*, double& number, JSValue&);
bool toBoolean(ExecState*) const;
TriState pureToBoolean() const;
// toNumber conversion is expected to be side effect free if an exception has
// been set in the ExecState already.
double toNumber(ExecState*) const;
Variant<JSBigInt*, double> toNumeric(ExecState*) const;
Variant<JSBigInt*, int32_t> toBigIntOrInt32(ExecState*) const;
// toNumber conversion if it can be done without side effects.
Optional<double> toNumberFromPrimitive() const;
JSString* toString(ExecState*) const; // On exception, this returns the empty string.
JSString* toStringOrNull(ExecState*) const; // On exception, this returns null, to make exception checks faster.
Identifier toPropertyKey(ExecState*) const;
WTF::String toWTFString(ExecState*) const;
JSObject* toObject(ExecState*) const;
JSObject* toObject(ExecState*, JSGlobalObject*) const;
// Integer conversions.
JS_EXPORT_PRIVATE double toInteger(ExecState*) const;
JS_EXPORT_PRIVATE double toIntegerPreserveNaN(ExecState*) const;
int32_t toInt32(ExecState*) const;
uint32_t toUInt32(ExecState*) const;
uint32_t toIndex(ExecState*, const char* errorName) const;
double toLength(ExecState*) const;
// Floating point conversions (this is a convenience function for WebCore;
// single precision float is not a representation used in JS or JSC).
float toFloat(ExecState* exec) const { return static_cast<float>(toNumber(exec)); }
// Object operations, with the toObject operation included.
JSValue get(ExecState*, PropertyName) const;
JSValue get(ExecState*, PropertyName, PropertySlot&) const;
JSValue get(ExecState*, unsigned propertyName) const;
JSValue get(ExecState*, unsigned propertyName, PropertySlot&) const;
JSValue get(ExecState*, uint64_t propertyName) const;
bool getPropertySlot(ExecState*, PropertyName, PropertySlot&) const;
template<typename CallbackWhenNoException> typename std::result_of<CallbackWhenNoException(bool, PropertySlot&)>::type getPropertySlot(ExecState*, PropertyName, CallbackWhenNoException) const;
template<typename CallbackWhenNoException> typename std::result_of<CallbackWhenNoException(bool, PropertySlot&)>::type getPropertySlot(ExecState*, PropertyName, PropertySlot&, CallbackWhenNoException) const;
bool getOwnPropertySlot(ExecState*, PropertyName, PropertySlot&) const;
bool put(ExecState*, PropertyName, JSValue, PutPropertySlot&);
bool putInline(ExecState*, PropertyName, JSValue, PutPropertySlot&);
JS_EXPORT_PRIVATE bool putToPrimitive(ExecState*, PropertyName, JSValue, PutPropertySlot&);
JS_EXPORT_PRIVATE bool putToPrimitiveByIndex(ExecState*, unsigned propertyName, JSValue, bool shouldThrow);
bool putByIndex(ExecState*, unsigned propertyName, JSValue, bool shouldThrow);
JSValue toThis(ExecState*, ECMAMode) const;
static bool equal(ExecState*, JSValue v1, JSValue v2);
static bool equalSlowCase(ExecState*, JSValue v1, JSValue v2);
static bool equalSlowCaseInline(ExecState*, JSValue v1, JSValue v2);
static bool strictEqual(ExecState*, JSValue v1, JSValue v2);
static bool strictEqualSlowCase(ExecState*, JSValue v1, JSValue v2);
static bool strictEqualSlowCaseInline(ExecState*, JSValue v1, JSValue v2);
static TriState pureStrictEqual(JSValue v1, JSValue v2);
bool isCell() const;
JSCell* asCell() const;
JS_EXPORT_PRIVATE bool isValidCallee();
Structure* structureOrNull() const;
JSValue structureOrUndefined() const;
JS_EXPORT_PRIVATE void dump(PrintStream&) const;
void dumpInContext(PrintStream&, DumpContext*) const;
void dumpInContextAssumingStructure(PrintStream&, DumpContext*, Structure*) const;
void dumpForBacktrace(PrintStream&) const;
JS_EXPORT_PRIVATE JSObject* synthesizePrototype(ExecState*) const;
bool requireObjectCoercible(ExecState*) const;
// Constants used for Int52. Int52 isn't part of JSValue right now, but JSValues may be
// converted to Int52s and back again.
static constexpr const unsigned numberOfInt52Bits = 52;
static constexpr const int64_t notInt52 = static_cast<int64_t>(1) << numberOfInt52Bits;
static constexpr const unsigned int52ShiftAmount = 12;
static ptrdiff_t offsetOfPayload() { return OBJECT_OFFSETOF(JSValue, u.asBits.payload); }
static ptrdiff_t offsetOfTag() { return OBJECT_OFFSETOF(JSValue, u.asBits.tag); }
#if USE(JSVALUE32_64)
/*
* On 32-bit platforms USE(JSVALUE32_64) should be defined, and we use a NaN-encoded
* form for immediates.
*
* The encoding makes use of unused NaN space in the IEEE754 representation. Any value
* with the top 13 bits set represents a QNaN (with the sign bit set). QNaN values
* can encode a 51-bit payload. Hardware produced and C-library payloads typically
* have a payload of zero. We assume that non-zero payloads are available to encode
* pointer and integer values. Since any 64-bit bit pattern where the top 15 bits are
* all set represents a NaN with a non-zero payload, we can use this space in the NaN
* ranges to encode other values (however there are also other ranges of NaN space that
* could have been selected).
*
* For JSValues that do not contain a double value, the high 32 bits contain the tag
* values listed in the enums below, which all correspond to NaN-space. In the case of
* cell, integer and bool values the lower 32 bits (the 'payload') contain the pointer
* integer or boolean value; in the case of all other tags the payload is 0.
*/
uint32_t tag() const;
int32_t payload() const;
// This should only be used by the LLInt C Loop interpreter and OSRExit code who needs
// synthesize JSValue from its "register"s holding tag and payload values.
explicit JSValue(int32_t tag, int32_t payload);
#elif USE(JSVALUE64)
/*
* On 64-bit platforms USE(JSVALUE64) should be defined, and we use a NaN-encoded
* form for immediates.
*
* The encoding makes use of unused NaN space in the IEEE754 representation. Any value
* with the top 13 bits set represents a QNaN (with the sign bit set). QNaN values
* can encode a 51-bit payload. Hardware produced and C-library payloads typically
* have a payload of zero. We assume that non-zero payloads are available to encode
* pointer and integer values. Since any 64-bit bit pattern where the top 15 bits are
* all set represents a NaN with a non-zero payload, we can use this space in the NaN
* ranges to encode other values (however there are also other ranges of NaN space that
* could have been selected).
*
* This range of NaN space is represented by 64-bit numbers begining with the 16-bit
* hex patterns 0xFFFE and 0xFFFF - we rely on the fact that no valid double-precision
* numbers will fall in these ranges.
*
* The top 16-bits denote the type of the encoded JSValue:
*
* Pointer { 0000:PPPP:PPPP:PPPP
* / 0001:****:****:****
* Double { ...
* \ FFFE:****:****:****
* Integer { FFFF:0000:IIII:IIII
*
* The scheme we have implemented encodes double precision values by performing a
* 64-bit integer addition of the value 2^48 to the number. After this manipulation
* no encoded double-precision value will begin with the pattern 0x0000 or 0xFFFF.
* Values must be decoded by reversing this operation before subsequent floating point
* operations may be peformed.
*
* 32-bit signed integers are marked with the 16-bit tag 0xFFFF.
*
* The tag 0x0000 denotes a pointer, or another form of tagged immediate. Boolean,
* null and undefined values are represented by specific, invalid pointer values:
*
* False: 0x06
* True: 0x07
* Undefined: 0x0a
* Null: 0x02
*
* These values have the following properties:
* - Bit 1 (TagBitTypeOther) is set for all four values, allowing real pointers to be
* quickly distinguished from all immediate values, including these invalid pointers.
* - With bit 3 is masked out (TagBitUndefined) Undefined and Null share the
* same value, allowing null & undefined to be quickly detected.
*
* No valid JSValue will have the bit pattern 0x0, this is used to represent array
* holes, and as a C++ 'no value' result (e.g. JSValue() has an internal value of 0).
*/
// These values are #defines since using static const integers here is a ~1% regression!
// This value is 2^48, used to encode doubles such that the encoded value will begin
// with a 16-bit pattern within the range 0x0001..0xFFFE.
#define DoubleEncodeOffset 0x1000000000000ll
// If all bits in the mask are set, this indicates an integer number,
// if any but not all are set this value is a double precision number.
#define TagTypeNumber 0xffff000000000000ll
// All non-numeric (bool, null, undefined) immediates have bit 2 set.
#define TagBitTypeOther 0x2ll
#define TagBitBool 0x4ll
#define TagBitUndefined 0x8ll
// Combined integer value for non-numeric immediates.
#define ValueFalse (TagBitTypeOther | TagBitBool | false)
#define ValueTrue (TagBitTypeOther | TagBitBool | true)
#define ValueUndefined (TagBitTypeOther | TagBitUndefined)
#define ValueNull (TagBitTypeOther)
// TagMask is used to check for all types of immediate values (either number or 'other').
#define TagMask (TagTypeNumber | TagBitTypeOther)
// These special values are never visible to JavaScript code; Empty is used to represent
// Array holes, and for uninitialized JSValues. Deleted is used in hash table code.
// These values would map to cell types in the JSValue encoding, but not valid GC cell
// pointer should have either of these values (Empty is null, deleted is at an invalid
// alignment for a GC cell, and in the zero page).
#define ValueEmpty 0x0ll
#define ValueDeleted 0x4ll
#define TagBitsWasm (TagBitTypeOther | 0x1)
#define TagWasmMask (TagTypeNumber | 0x7)
// We tag Wasm non-JSCell pointers with a 3 at the bottom. We can test if a 64-bit JSValue pattern
// is a Wasm callee by masking the upper 16 bits and the lower 3 bits, and seeing if
// the resulting value is 3. The full test is: x & TagWasmMask == TagBitsWasm
// This works because the lower 3 bits of the non-number immediate values are as follows:
// undefined: 0b010
// null: 0b010
// true: 0b111
// false: 0b110
// The test rejects all of these because none have just the value 3 in their lower 3 bits.
// The test rejects all numbers because they have non-zero upper 16 bits.
// The test also rejects normal cells because they won't have the number 3 as
// their lower 3 bits. Note, this bit pattern also allows the normal JSValue isCell(), etc,
// predicates to work on a Wasm::Callee because the various tests will fail if you
// bit casted a boxed Wasm::Callee* to a JSValue. isCell() would fail since it sees
// TagBitTypeOther. The other tests also trivially fail, since it won't be a number,
// and it won't be equal to null, undefined, true, or false. The isBoolean() predicate
// will fail because we won't have TagBitBool set.
#endif
private:
template <class T> JSValue(WriteBarrierBase<T, WriteBarrierTraitsSelect<T>>);
enum HashTableDeletedValueTag { HashTableDeletedValue };
JSValue(HashTableDeletedValueTag);
inline const JSValue asValue() const { return *this; }
JS_EXPORT_PRIVATE double toNumberSlowCase(ExecState*) const;
JS_EXPORT_PRIVATE JSString* toStringSlowCase(ExecState*, bool returnEmptyStringOnError) const;
JS_EXPORT_PRIVATE WTF::String toWTFStringSlowCase(ExecState*) const;
JS_EXPORT_PRIVATE JSObject* toObjectSlowCase(ExecState*, JSGlobalObject*) const;
JS_EXPORT_PRIVATE JSValue toThisSlowCase(ExecState*, ECMAMode) const;
EncodedValueDescriptor u;
};
typedef IntHash<EncodedJSValue> EncodedJSValueHash;
#if USE(JSVALUE32_64)
struct EncodedJSValueHashTraits : HashTraits<EncodedJSValue> {
static const bool emptyValueIsZero = false;
static EncodedJSValue emptyValue() { return JSValue::encode(JSValue()); }
static void constructDeletedValue(EncodedJSValue& slot) { slot = JSValue::encode(JSValue(JSValue::HashTableDeletedValue)); }
static bool isDeletedValue(EncodedJSValue value) { return value == JSValue::encode(JSValue(JSValue::HashTableDeletedValue)); }
};
#else
struct EncodedJSValueHashTraits : HashTraits<EncodedJSValue> {
static void constructDeletedValue(EncodedJSValue& slot) { slot = JSValue::encode(JSValue(JSValue::HashTableDeletedValue)); }
static bool isDeletedValue(EncodedJSValue value) { return value == JSValue::encode(JSValue(JSValue::HashTableDeletedValue)); }
};
#endif
typedef std::pair<EncodedJSValue, SourceCodeRepresentation> EncodedJSValueWithRepresentation;
struct EncodedJSValueWithRepresentationHashTraits : HashTraits<EncodedJSValueWithRepresentation> {
static const bool emptyValueIsZero = false;
static EncodedJSValueWithRepresentation emptyValue() { return std::make_pair(JSValue::encode(JSValue()), SourceCodeRepresentation::Other); }
static void constructDeletedValue(EncodedJSValueWithRepresentation& slot) { slot = std::make_pair(JSValue::encode(JSValue(JSValue::HashTableDeletedValue)), SourceCodeRepresentation::Other); }
static bool isDeletedValue(EncodedJSValueWithRepresentation value) { return value == std::make_pair(JSValue::encode(JSValue(JSValue::HashTableDeletedValue)), SourceCodeRepresentation::Other); }
};
struct EncodedJSValueWithRepresentationHash {
static unsigned hash(const EncodedJSValueWithRepresentation& value)
{
return WTF::pairIntHash(EncodedJSValueHash::hash(value.first), IntHash<SourceCodeRepresentation>::hash(value.second));
}
static bool equal(const EncodedJSValueWithRepresentation& a, const EncodedJSValueWithRepresentation& b)
{
return a == b;
}
static const bool safeToCompareToEmptyOrDeleted = true;
};
// Stand-alone helper functions.
inline JSValue jsNull()
{
return JSValue(JSValue::JSNull);
}
inline JSValue jsUndefined()
{
return JSValue(JSValue::JSUndefined);
}
inline JSValue jsTDZValue()
{
return JSValue();
}
inline JSValue jsBoolean(bool b)
{
return b ? JSValue(JSValue::JSTrue) : JSValue(JSValue::JSFalse);
}
ALWAYS_INLINE JSValue jsDoubleNumber(double d)
{
ASSERT(JSValue(JSValue::EncodeAsDouble, d).isNumber());
return JSValue(JSValue::EncodeAsDouble, d);
}
ALWAYS_INLINE JSValue jsNumber(double d)
{
ASSERT(JSValue(d).isNumber());
ASSERT(!isImpureNaN(d));
return JSValue(d);
}
ALWAYS_INLINE JSValue jsNumber(const MediaTime& t)
{
return jsNumber(t.toDouble());
}
ALWAYS_INLINE JSValue jsNumber(char i)
{
return JSValue(i);
}
ALWAYS_INLINE JSValue jsNumber(unsigned char i)
{
return JSValue(i);
}
ALWAYS_INLINE JSValue jsNumber(short i)
{
return JSValue(i);
}
ALWAYS_INLINE JSValue jsNumber(unsigned short i)
{
return JSValue(i);
}
ALWAYS_INLINE JSValue jsNumber(int i)
{
return JSValue(i);
}
ALWAYS_INLINE JSValue jsNumber(unsigned i)
{
return JSValue(i);
}
ALWAYS_INLINE JSValue jsNumber(long i)
{
return JSValue(i);
}
ALWAYS_INLINE JSValue jsNumber(unsigned long i)
{
return JSValue(i);
}
ALWAYS_INLINE JSValue jsNumber(long long i)
{
return JSValue(i);
}
ALWAYS_INLINE JSValue jsNumber(unsigned long long i)
{
return JSValue(i);
}
ALWAYS_INLINE EncodedJSValue encodedJSUndefined()
{
return JSValue::encode(jsUndefined());
}
ALWAYS_INLINE EncodedJSValue encodedJSValue()
{
return JSValue::encode(JSValue());
}
inline bool operator==(const JSValue a, const JSCell* b) { return a == JSValue(b); }
inline bool operator==(const JSCell* a, const JSValue b) { return JSValue(a) == b; }
inline bool operator!=(const JSValue a, const JSCell* b) { return a != JSValue(b); }
inline bool operator!=(const JSCell* a, const JSValue b) { return JSValue(a) != b; }
bool isThisValueAltered(const PutPropertySlot&, JSObject* baseObject);
// See section 7.2.9: https://tc39.github.io/ecma262/#sec-samevalue
bool sameValue(ExecState*, JSValue a, JSValue b);
} // namespace JSC
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