Imported WebKit commit 2ea9d364d0f6efa8fa64acf19f451504c59be0e4 (http://svn.webkit.org/repository/webkit/trunk@104285)

1 files changed, 478 insertions, 0 deletions

diff --git a/Source/JavaScriptCore/runtime/JSValue.h b/Source/JavaScriptCore/runtime/JSValue.h
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+/*
+ *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
+ *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
+ *  Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009 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.
+ *
+ */
+
+#ifndef JSValue_h
+#define JSValue_h
+
+#include <math.h>
+#include <stddef.h> // for size_t
+#include <stdint.h>
+#include <wtf/AlwaysInline.h>
+#include <wtf/Assertions.h>
+#include <wtf/HashMap.h>
+#include <wtf/HashTraits.h>
+#include <wtf/MathExtras.h>
+#include <wtf/StdLibExtras.h>
+
+namespace JSC {
+
+    class ExecState;
+    class Identifier;
+    class JSCell;
+    class JSGlobalData;
+    class JSGlobalObject;
+    class JSObject;
+    class JSString;
+    class PropertySlot;
+    class PutPropertySlot;
+    class UString;
+#if ENABLE(DFG_JIT)
+    namespace DFG {
+        class AssemblyHelpers;
+        class JITCompiler;
+        class JITCodeGenerator;
+        class JSValueSource;
+        class OSRExitCompiler;
+        class SpeculativeJIT;
+    }
+#endif
+
+    struct ClassInfo;
+    struct Instruction;
+    struct MethodTable;
+
+    template <class T> class WriteBarrierBase;
+
+    enum PreferredPrimitiveType { NoPreference, PreferNumber, PreferString };
+
+
+#if USE(JSVALUE32_64)
+    typedef int64_t EncodedJSValue;
+#else
+    typedef void* EncodedJSValue;
+#endif
+    
+    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
+    };
+
+    // This implements ToInt32, defined in ECMA-262 9.5.
+    int32_t toInt32(double);
+
+    // This implements ToUInt32, defined in ECMA-262 9.6.
+    inline uint32_t toUInt32(double number)
+    {
+        // As commented in the spec, the operation of ToInt32 and ToUint32 only differ
+        // in how the result is interpreted; see NOTEs in sections 9.5 and 9.6.
+        return toInt32(number);
+    }
+
+    class JSValue {
+        friend struct EncodedJSValueHashTraits;
+        friend class JIT;
+        friend class JITStubs;
+        friend class JITStubCall;
+        friend class JSInterfaceJIT;
+        friend class SpecializedThunkJIT;
+#if ENABLE(DFG_JIT)
+        friend class DFG::AssemblyHelpers;
+        friend class DFG::JITCompiler;
+        friend class DFG::JITCodeGenerator;
+        friend class DFG::JSValueSource;
+        friend class DFG::OSRExitCompiler;
+        friend class DFG::SpeculativeJIT;
+#endif
+
+    public:
+        static EncodedJSValue encode(JSValue);
+        static JSValue decode(EncodedJSValue);
+
+        enum JSNullTag { JSNull };
+        enum JSUndefinedTag { JSUndefined };
+        enum JSTrueTag { JSTrue };
+        enum JSFalseTag { JSFalse };
+        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);
+
+        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;
+        double asDouble() const;
+        bool asBoolean() const;
+        double asNumber() const;
+
+        // Querying the type.
+        bool isEmpty() const;
+        bool isUndefined() const;
+        bool isNull() const;
+        bool isUndefinedOrNull() const;
+        bool isBoolean() const;
+        bool isNumber() const;
+        bool isString() const;
+        bool isPrimitive() const;
+        bool isGetterSetter() const;
+        bool isObject() const;
+        bool inherits(const ClassInfo*) const;
+        
+        // Extracting the value.
+        bool getString(ExecState* exec, UString&) const;
+        UString getString(ExecState* exec) 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;
+
+        // toNumber conversion is expected to be side effect free if an exception has
+        // been set in the ExecState already.
+        double toNumber(ExecState*) const;
+        UString toString(ExecState*) const;
+        JSString* toPrimitiveString(ExecState*) const;
+        JSObject* toObject(ExecState*) const;
+        JSObject* toObject(ExecState*, JSGlobalObject*) const;
+
+        // Integer conversions.
+        double toInteger(ExecState*) const;
+        double toIntegerPreserveNaN(ExecState*) const;
+        int32_t toInt32(ExecState*) const;
+        uint32_t toUInt32(ExecState*) const;
+
+        // Floating point conversions (this is a convenience method for webcore;
+        // signle 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*, const Identifier& propertyName) const;
+        JSValue get(ExecState*, const Identifier& propertyName, PropertySlot&) const;
+        JSValue get(ExecState*, unsigned propertyName) const;
+        JSValue get(ExecState*, unsigned propertyName, PropertySlot&) const;
+        void put(ExecState*, const Identifier& propertyName, JSValue, PutPropertySlot&);
+        void putDirect(ExecState*, const Identifier& propertyName, JSValue, PutPropertySlot&);
+        void put(ExecState*, unsigned propertyName, JSValue);
+
+        JSObject* toThisObject(ExecState*) const;
+
+        static bool equal(ExecState* exec, JSValue v1, JSValue v2);
+        static bool equalSlowCase(ExecState* exec, JSValue v1, JSValue v2);
+        static bool equalSlowCaseInline(ExecState* exec, JSValue v1, JSValue v2);
+        static bool strictEqual(ExecState* exec, JSValue v1, JSValue v2);
+        static bool strictEqualSlowCase(ExecState* exec, JSValue v1, JSValue v2);
+        static bool strictEqualSlowCaseInline(ExecState* exec, JSValue v1, JSValue v2);
+
+        bool isCell() const;
+        JSCell* asCell() const;
+        bool isValidCallee();
+
+#ifndef NDEBUG
+        char* description();
+#endif
+
+    private:
+        template <class T> JSValue(WriteBarrierBase<T>);
+
+        enum HashTableDeletedValueTag { HashTableDeletedValue };
+        JSValue(HashTableDeletedValueTag);
+
+        inline const JSValue asValue() const { return *this; }
+        double toNumberSlowCase(ExecState*) const;
+        JSObject* toObjectSlowCase(ExecState*, JSGlobalObject*) const;
+        JSObject* toThisObjectSlowCase(ExecState*) const;
+
+        JSObject* synthesizePrototype(ExecState*) const;
+        JSObject* synthesizeObject(ExecState*) const;
+
+#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.
+         */
+        enum { Int32Tag =        0xffffffff };
+        enum { BooleanTag =      0xfffffffe };
+        enum { NullTag =         0xfffffffd };
+        enum { UndefinedTag =    0xfffffffc };
+        enum { CellTag =         0xfffffffb };
+        enum { EmptyValueTag =   0xfffffffa };
+        enum { DeletedValueTag = 0xfffffff9 };
+
+        enum { LowestTag =  DeletedValueTag };
+
+        uint32_t tag() const;
+        int32_t payload() const;
+#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 begin 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 my 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
+#endif
+
+        EncodedValueDescriptor u;
+    };
+
+#if USE(JSVALUE32_64)
+    typedef IntHash<EncodedJSValue> EncodedJSValueHash;
+
+    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
+    typedef PtrHash<EncodedJSValue> EncodedJSValueHash;
+
+    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 HashMap<EncodedJSValue, unsigned, EncodedJSValueHash, EncodedJSValueHashTraits> JSValueMap;
+
+    // Stand-alone helper functions.
+    inline JSValue jsNull()
+    {
+        return JSValue(JSValue::JSNull);
+    }
+
+    inline JSValue jsUndefined()
+    {
+        return JSValue(JSValue::JSUndefined);
+    }
+
+    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());
+        return JSValue(d);
+    }
+
+    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);
+    }
+
+    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; }
+
+} // namespace JSC
+
+#endif // JSValue_h