Merge WebKit at r84325: Initial merge by git.

Change-Id: Ic1a909300ecc0a13ddc6b4e784371d2ac6e3d59b

1 files changed, 117 insertions, 428 deletions

diff --git a/Source/JavaScriptCore/runtime/JSValue.h b/Source/JavaScriptCore/runtime/JSValue.h
index 098123e..de50011 100644
--- a/Source/JavaScriptCore/runtime/JSValue.h
+++ b/Source/JavaScriptCore/runtime/JSValue.h
@@ -30,15 +30,18 @@
 #include <wtf/Assertions.h>
 #include <wtf/HashTraits.h>
 #include <wtf/MathExtras.h>
+#include <wtf/StdLibExtras.h>
 
 namespace JSC {
 
+    extern const double NaN;
+    extern const double Inf;
+
     class ExecState;
     class Identifier;
     class JSCell;
     class JSGlobalData;
     class JSGlobalObject;
-    class JSImmediate;
     class JSObject;
     class JSString;
     class PropertySlot;
@@ -48,7 +51,6 @@ namespace JSC {
     struct ClassInfo;
     struct Instruction;
 
-    template <class T> class DeprecatedPtr;
     template <class T> class WriteBarrierBase;
 
     enum PreferredPrimitiveType { NoPreference, PreferNumber, PreferString };
@@ -61,7 +63,7 @@ namespace JSC {
 #endif
     
     union EncodedValueDescriptor {
-        EncodedJSValue asEncodedJSValue;
+        int64_t asInt64;
 #if USE(JSVALUE32_64)
         double asDouble;
 #elif USE(JSVALUE64)
@@ -95,7 +97,6 @@ namespace JSC {
     }
 
     class JSValue {
-        friend class JSImmediate;
         friend struct EncodedJSValueHashTraits;
         friend class JIT;
         friend class JITStubs;
@@ -104,14 +105,9 @@ namespace JSC {
         friend class SpecializedThunkJIT;
 
     public:
-        static EncodedJSValue encode(JSValue value);
-        static JSValue decode(EncodedJSValue ptr);
-#if USE(JSVALUE64)
-    private:
-        static JSValue makeImmediate(intptr_t value);
-        intptr_t immediateValue();
-    public:
-#endif
+        static EncodedJSValue encode(JSValue);
+        static JSValue decode(EncodedJSValue);
+
         enum JSNullTag { JSNull };
         enum JSUndefinedTag { JSUndefined };
         enum JSTrueTag { JSTrue };
@@ -239,7 +235,6 @@ namespace JSC {
 #endif
 
     private:
-        template <class T> JSValue(DeprecatedPtr<T>);
         template <class T> JSValue(WriteBarrierBase<T>);
 
         enum HashTableDeletedValueTag { HashTableDeletedValue };
@@ -253,24 +248,120 @@ namespace JSC {
         JSObject* synthesizeObject(ExecState*) const;
 
 #if USE(JSVALUE32_64)
-        enum { NullTag =         0xffffffff };
-        enum { UndefinedTag =    0xfffffffe };
-        enum { Int32Tag =        0xfffffffd };
-        enum { CellTag =         0xfffffffc };
-        enum { TrueTag =         0xfffffffb };
-        enum { FalseTag =        0xfffffffa };
-        enum { EmptyValueTag =   0xfffffff9 };
-        enum { DeletedValueTag = 0xfffffff8 };
-        
+        /*
+         * 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;
-
-        EncodedValueDescriptor u;
 #elif USE(JSVALUE64)
-        JSCell* m_ptr;
+        /*
+         * 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)
@@ -373,409 +464,7 @@ namespace JSC {
     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; }
 
-    ALWAYS_INLINE int32_t JSValue::toInt32(ExecState* exec) const
-    {
-        if (isInt32())
-            return asInt32();
-        return JSC::toInt32(toNumber(exec));
-    }
-
-    inline uint32_t JSValue::toUInt32(ExecState* exec) const
-    {
-        // See comment on JSC::toUInt32, above.
-        return toInt32(exec);
-    }
-
-#if USE(JSVALUE32_64)
-    inline JSValue jsNaN()
-    {
-        return JSValue(nonInlineNaN());
-    }
-
-    // JSValue member functions.
-    inline EncodedJSValue JSValue::encode(JSValue value)
-    {
-        return value.u.asEncodedJSValue;
-    }
-
-    inline JSValue JSValue::decode(EncodedJSValue encodedJSValue)
-    {
-        JSValue v;
-        v.u.asEncodedJSValue = encodedJSValue;
-        return v;
-    }
-
-    inline JSValue::JSValue()
-    {
-        u.asBits.tag = EmptyValueTag;
-        u.asBits.payload = 0;
-    }
-
-    inline JSValue::JSValue(JSNullTag)
-    {
-        u.asBits.tag = NullTag;
-        u.asBits.payload = 0;
-    }
-    
-    inline JSValue::JSValue(JSUndefinedTag)
-    {
-        u.asBits.tag = UndefinedTag;
-        u.asBits.payload = 0;
-    }
-    
-    inline JSValue::JSValue(JSTrueTag)
-    {
-        u.asBits.tag = TrueTag;
-        u.asBits.payload = 0;
-    }
-    
-    inline JSValue::JSValue(JSFalseTag)
-    {
-        u.asBits.tag = FalseTag;
-        u.asBits.payload = 0;
-    }
-
-    inline JSValue::JSValue(HashTableDeletedValueTag)
-    {
-        u.asBits.tag = DeletedValueTag;
-        u.asBits.payload = 0;
-    }
-
-    inline JSValue::JSValue(JSCell* ptr)
-    {
-        if (ptr)
-            u.asBits.tag = CellTag;
-        else
-            u.asBits.tag = EmptyValueTag;
-        u.asBits.payload = reinterpret_cast<int32_t>(ptr);
-#if ENABLE(JSC_ZOMBIES)
-        ASSERT(!isZombie());
-#endif
-    }
-
-    inline JSValue::JSValue(const JSCell* ptr)
-    {
-        if (ptr)
-            u.asBits.tag = CellTag;
-        else
-            u.asBits.tag = EmptyValueTag;
-        u.asBits.payload = reinterpret_cast<int32_t>(const_cast<JSCell*>(ptr));
-#if ENABLE(JSC_ZOMBIES)
-        ASSERT(!isZombie());
-#endif
-    }
-
-    inline JSValue::operator bool() const
-    {
-        ASSERT(tag() != DeletedValueTag);
-        return tag() != EmptyValueTag;
-    }
-
-    inline bool JSValue::operator==(const JSValue& other) const
-    {
-        return u.asEncodedJSValue == other.u.asEncodedJSValue;
-    }
-
-    inline bool JSValue::operator!=(const JSValue& other) const
-    {
-        return u.asEncodedJSValue != other.u.asEncodedJSValue;
-    }
-
-    inline bool JSValue::isUndefined() const
-    {
-        return tag() == UndefinedTag;
-    }
-
-    inline bool JSValue::isNull() const
-    {
-        return tag() == NullTag;
-    }
-
-    inline bool JSValue::isUndefinedOrNull() const
-    {
-        return isUndefined() || isNull();
-    }
-
-    inline bool JSValue::isCell() const
-    {
-        return tag() == CellTag;
-    }
-
-    inline bool JSValue::isInt32() const
-    {
-        return tag() == Int32Tag;
-    }
-
-    inline bool JSValue::isUInt32() const
-    {
-        return tag() == Int32Tag && asInt32() > -1;
-    }
-
-    inline bool JSValue::isDouble() const
-    {
-        return tag() < LowestTag;
-    }
-
-    inline bool JSValue::isTrue() const
-    {
-        return tag() == TrueTag;
-    }
-
-    inline bool JSValue::isFalse() const
-    {
-        return tag() == FalseTag;
-    }
-
-    inline uint32_t JSValue::tag() const
-    {
-        return u.asBits.tag;
-    }
-    
-    inline int32_t JSValue::payload() const
-    {
-        return u.asBits.payload;
-    }
-    
-    inline int32_t JSValue::asInt32() const
-    {
-        ASSERT(isInt32());
-        return u.asBits.payload;
-    }
-    
-    inline uint32_t JSValue::asUInt32() const
-    {
-        ASSERT(isUInt32());
-        return u.asBits.payload;
-    }
-    
-    inline double JSValue::asDouble() const
-    {
-        ASSERT(isDouble());
-        return u.asDouble;
-    }
-    
-    ALWAYS_INLINE JSCell* JSValue::asCell() const
-    {
-        ASSERT(isCell());
-        return reinterpret_cast<JSCell*>(u.asBits.payload);
-    }
-
-    ALWAYS_INLINE JSValue::JSValue(EncodeAsDoubleTag, double d)
-    {
-        u.asDouble = d;
-    }
-
-    inline JSValue::JSValue(double d)
-    {
-        const int32_t asInt32 = static_cast<int32_t>(d);
-        if (asInt32 != d || (!asInt32 && signbit(d))) { // true for -0.0
-            u.asDouble = d;
-            return;
-        }
-        *this = JSValue(static_cast<int32_t>(d));
-    }
-
-    inline JSValue::JSValue(char i)
-    {
-        *this = JSValue(static_cast<int32_t>(i));
-    }
-
-    inline JSValue::JSValue(unsigned char i)
-    {
-        *this = JSValue(static_cast<int32_t>(i));
-    }
-
-    inline JSValue::JSValue(short i)
-    {
-        *this = JSValue(static_cast<int32_t>(i));
-    }
-
-    inline JSValue::JSValue(unsigned short i)
-    {
-        *this = JSValue(static_cast<int32_t>(i));
-    }
-
-    inline JSValue::JSValue(int i)
-    {
-        u.asBits.tag = Int32Tag;
-        u.asBits.payload = i;
-    }
-
-    inline JSValue::JSValue(unsigned i)
-    {
-        if (static_cast<int32_t>(i) < 0) {
-            *this = JSValue(static_cast<double>(i));
-            return;
-        }
-        *this = JSValue(static_cast<int32_t>(i));
-    }
-
-    inline JSValue::JSValue(long i)
-    {
-        if (static_cast<int32_t>(i) != i) {
-            *this = JSValue(static_cast<double>(i));
-            return;
-        }
-        *this = JSValue(static_cast<int32_t>(i));
-    }
-
-    inline JSValue::JSValue(unsigned long i)
-    {
-        if (static_cast<uint32_t>(i) != i) {
-            *this = JSValue(static_cast<double>(i));
-            return;
-        }
-        *this = JSValue(static_cast<uint32_t>(i));
-    }
-
-    inline JSValue::JSValue(long long i)
-    {
-        if (static_cast<int32_t>(i) != i) {
-            *this = JSValue(static_cast<double>(i));
-            return;
-        }
-        *this = JSValue(static_cast<int32_t>(i));
-    }
-
-    inline JSValue::JSValue(unsigned long long i)
-    {
-        if (static_cast<uint32_t>(i) != i) {
-            *this = JSValue(static_cast<double>(i));
-            return;
-        }
-        *this = JSValue(static_cast<uint32_t>(i));
-    }
-
-    inline bool JSValue::isNumber() const
-    {
-        return isInt32() || isDouble();
-    }
-
-    inline bool JSValue::isBoolean() const
-    {
-        return isTrue() || isFalse();
-    }
-
-    inline bool JSValue::getBoolean(bool& v) const
-    {
-        if (isTrue()) {
-            v = true;
-            return true;
-        }
-        if (isFalse()) {
-            v = false;
-            return true;
-        }
-        
-        return false;
-    }
-
-    inline bool JSValue::getBoolean() const
-    {
-        ASSERT(isBoolean());
-        return tag() == TrueTag;
-    }
-
-    inline double JSValue::uncheckedGetNumber() const
-    {
-        ASSERT(isNumber());
-        return isInt32() ? asInt32() : asDouble();
-    }
-
-    ALWAYS_INLINE JSValue JSValue::toJSNumber(ExecState* exec) const
-    {
-        return isNumber() ? asValue() : jsNumber(this->toNumber(exec));
-    }
-
-    inline bool JSValue::getNumber(double& result) const
-    {
-        if (isInt32()) {
-            result = asInt32();
-            return true;
-        }
-        if (isDouble()) {
-            result = asDouble();
-            return true;
-        }
-        return false;
-    }
-
-#else // USE(JSVALUE32_64)
-
-    // JSValue member functions.
-    inline EncodedJSValue JSValue::encode(JSValue value)
-    {
-        return reinterpret_cast<EncodedJSValue>(value.m_ptr);
-    }
-
-    inline JSValue JSValue::decode(EncodedJSValue ptr)
-    {
-        return JSValue(reinterpret_cast<JSCell*>(ptr));
-    }
-
-    inline JSValue JSValue::makeImmediate(intptr_t value)
-    {
-        return JSValue(reinterpret_cast<JSCell*>(value));
-    }
-
-    inline intptr_t JSValue::immediateValue()
-    {
-        return reinterpret_cast<intptr_t>(m_ptr);
-    }
-    
-    // 0x0 can never occur naturally because it has a tag of 00, indicating a pointer value, but a payload of 0x0, which is in the (invalid) zero page.
-    inline JSValue::JSValue()
-        : m_ptr(0)
-    {
-    }
-
-    // 0x4 can never occur naturally because it has a tag of 00, indicating a pointer value, but a payload of 0x4, which is in the (invalid) zero page.
-    inline JSValue::JSValue(HashTableDeletedValueTag)
-        : m_ptr(reinterpret_cast<JSCell*>(0x4))
-    {
-    }
-
-    inline JSValue::JSValue(JSCell* ptr)
-        : m_ptr(ptr)
-    {
-#if ENABLE(JSC_ZOMBIES)
-        ASSERT(!isZombie());
-#endif
-    }
-
-    inline JSValue::JSValue(const JSCell* ptr)
-        : m_ptr(const_cast<JSCell*>(ptr))
-    {
-#if ENABLE(JSC_ZOMBIES)
-        ASSERT(!isZombie());
-#endif
-    }
-
-    inline JSValue::operator bool() const
-    {
-        return m_ptr;
-    }
-
-    inline bool JSValue::operator==(const JSValue& other) const
-    {
-        return m_ptr == other.m_ptr;
-    }
-
-    inline bool JSValue::operator!=(const JSValue& other) const
-    {
-        return m_ptr != other.m_ptr;
-    }
-
-    inline bool JSValue::isUndefined() const
-    {
-        return asValue() == jsUndefined();
-    }
-
-    inline bool JSValue::isNull() const
-    {
-        return asValue() == jsNull();
-    }
-#endif // USE(JSVALUE32_64)
+    bool isZombie(const JSCell*);
 
 } // namespace JSC