/* * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved. * Copyright (C) 2006 Alexey Proskuryakov (ap@webkit.org) * * 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 JSImmediate_h #define JSImmediate_h #include <wtf/Platform.h> #if !USE(JSVALUE32_64) #include <wtf/Assertions.h> #include <wtf/AlwaysInline.h> #include <wtf/MathExtras.h> #include <wtf/StdLibExtras.h> #include "JSValue.h" #include <limits> #include <limits.h> #include <stdarg.h> #include <stdint.h> #include <stdlib.h> namespace JSC { class ExecState; class JSCell; class JSFastMath; class JSGlobalData; class JSObject; class UString; #if USE(JSVALUE64) inline intptr_t reinterpretDoubleToIntptr(double value) { return WTF::bitwise_cast<intptr_t>(value); } inline double reinterpretIntptrToDouble(intptr_t value) { return WTF::bitwise_cast<double>(value); } #endif /* * A JSValue* is either a pointer to a cell (a heap-allocated object) or an immediate (a type-tagged * value masquerading as a pointer). The low two bits in a JSValue* are available for type tagging * because allocator alignment guarantees they will be 00 in cell pointers. * * For example, on a 32 bit system: * * JSCell*: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 00 * [ high 30 bits: pointer address ] [ low 2 bits -- always 0 ] * JSImmediate: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX TT * [ high 30 bits: 'payload' ] [ low 2 bits -- tag ] * * Where the bottom two bits are non-zero they either indicate that the immediate is a 31 bit signed * integer, or they mark the value as being an immediate of a type other than integer, with a secondary * tag used to indicate the exact type. * * Where the lowest bit is set (TT is equal to 01 or 11) the high 31 bits form a 31 bit signed int value. * Where TT is equal to 10 this indicates this is a type of immediate other than an integer, and the next * two bits will form an extended tag. * * 31 bit signed int: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXX X1 * [ high 30 bits of the value ] [ high bit part of value ] * Other: YYYYYYYYYYYYYYYYYYYYYYYYYYYY ZZ 10 * [ extended 'payload' ] [ extended tag ] [ tag 'other' ] * * Where the first bit of the extended tag is set this flags the value as being a boolean, and the following * bit would flag the value as undefined. If neither bits are set, the value is null. * * Other: YYYYYYYYYYYYYYYYYYYYYYYYYYYY UB 10 * [ extended 'payload' ] [ undefined | bool ] [ tag 'other' ] * * For boolean value the lowest bit in the payload holds the value of the bool, all remaining bits are zero. * For undefined or null immediates the payload is zero. * * Boolean: 000000000000000000000000000V 01 10 * [ boolean value ] [ bool ] [ tag 'other' ] * Undefined: 0000000000000000000000000000 10 10 * [ zero ] [ undefined ] [ tag 'other' ] * Null: 0000000000000000000000000000 00 10 * [ zero ] [ zero ] [ tag 'other' ] */ /* * On 64-bit platforms, we support an alternative encoding form for immediates, if * USE(JSVALUE64) is defined. When this format is used, double precision * floating point values may also be encoded as JSImmediates. * * 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 scheme we have implemented encodes double precision values by adding 2^48 to the * 64-bit integer representation of the number. After this manipulation, no encoded * double-precision value will begin with the pattern 0x0000 or 0xFFFF. * * The top 16-bits denote the type of the encoded JSImmediate: * * Pointer: 0000:PPPP:PPPP:PPPP * 0001:****:****:**** * Double:{ ... * FFFE:****:****:**** * Integer: FFFF:0000:IIII:IIII * * 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 encoded in the same manner as the default format. */ class JSImmediate { private: friend class JIT; friend class JSValue; friend class JSFastMath; friend JSValue jsNumber(ExecState* exec, double d); friend JSValue jsNumber(ExecState*, char i); friend JSValue jsNumber(ExecState*, unsigned char i); friend JSValue jsNumber(ExecState*, short i); friend JSValue jsNumber(ExecState*, unsigned short i); friend JSValue jsNumber(ExecState* exec, int i); friend JSValue jsNumber(ExecState* exec, unsigned i); friend JSValue jsNumber(ExecState* exec, long i); friend JSValue jsNumber(ExecState* exec, unsigned long i); friend JSValue jsNumber(ExecState* exec, long long i); friend JSValue jsNumber(ExecState* exec, unsigned long long i); friend JSValue jsNumber(JSGlobalData* globalData, double d); friend JSValue jsNumber(JSGlobalData* globalData, short i); friend JSValue jsNumber(JSGlobalData* globalData, unsigned short i); friend JSValue jsNumber(JSGlobalData* globalData, int i); friend JSValue jsNumber(JSGlobalData* globalData, unsigned i); friend JSValue jsNumber(JSGlobalData* globalData, long i); friend JSValue jsNumber(JSGlobalData* globalData, unsigned long i); friend JSValue jsNumber(JSGlobalData* globalData, long long i); friend JSValue jsNumber(JSGlobalData* globalData, unsigned long long i); #if USE(JSVALUE64) // 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. static const intptr_t TagTypeNumber = 0xffff000000000000ll; // 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. static const intptr_t DoubleEncodeOffset = 0x1000000000000ll; #else static const intptr_t TagTypeNumber = 0x1; // bottom bit set indicates integer, this dominates the following bit #endif static const intptr_t TagBitTypeOther = 0x2; // second bit set indicates immediate other than an integer static const intptr_t TagMask = TagTypeNumber | TagBitTypeOther; static const intptr_t ExtendedTagMask = 0xC; // extended tag holds a further two bits static const intptr_t ExtendedTagBitBool = 0x4; static const intptr_t ExtendedTagBitUndefined = 0x8; static const intptr_t FullTagTypeMask = TagMask | ExtendedTagMask; static const intptr_t FullTagTypeBool = TagBitTypeOther | ExtendedTagBitBool; static const intptr_t FullTagTypeUndefined = TagBitTypeOther | ExtendedTagBitUndefined; static const intptr_t FullTagTypeNull = TagBitTypeOther; #if USE(JSVALUE64) static const int32_t IntegerPayloadShift = 0; #else static const int32_t IntegerPayloadShift = 1; #endif static const int32_t ExtendedPayloadShift = 4; static const intptr_t ExtendedPayloadBitBoolValue = 1 << ExtendedPayloadShift; static const int32_t signBit = 0x80000000; static ALWAYS_INLINE bool isImmediate(JSValue v) { return rawValue(v) & TagMask; } static ALWAYS_INLINE bool isNumber(JSValue v) { return rawValue(v) & TagTypeNumber; } static ALWAYS_INLINE bool isIntegerNumber(JSValue v) { #if USE(JSVALUE64) return (rawValue(v) & TagTypeNumber) == TagTypeNumber; #else return isNumber(v); #endif } #if USE(JSVALUE64) static ALWAYS_INLINE bool isDouble(JSValue v) { return isNumber(v) && !isIntegerNumber(v); } #endif static ALWAYS_INLINE bool isPositiveIntegerNumber(JSValue v) { // A single mask to check for the sign bit and the number tag all at once. return (rawValue(v) & (signBit | TagTypeNumber)) == TagTypeNumber; } static ALWAYS_INLINE bool isBoolean(JSValue v) { return (rawValue(v) & FullTagTypeMask) == FullTagTypeBool; } static ALWAYS_INLINE bool isUndefinedOrNull(JSValue v) { // Undefined and null share the same value, bar the 'undefined' bit in the extended tag. return (rawValue(v) & ~ExtendedTagBitUndefined) == FullTagTypeNull; } static JSValue from(char); static JSValue from(signed char); static JSValue from(unsigned char); static JSValue from(short); static JSValue from(unsigned short); static JSValue from(int); static JSValue from(unsigned); static JSValue from(long); static JSValue from(unsigned long); static JSValue from(long long); static JSValue from(unsigned long long); static JSValue from(double); static ALWAYS_INLINE bool isEitherImmediate(JSValue v1, JSValue v2) { return (rawValue(v1) | rawValue(v2)) & TagMask; } static ALWAYS_INLINE bool areBothImmediate(JSValue v1, JSValue v2) { return isImmediate(v1) & isImmediate(v2); } static ALWAYS_INLINE bool areBothImmediateIntegerNumbers(JSValue v1, JSValue v2) { #if USE(JSVALUE64) return (rawValue(v1) & rawValue(v2) & TagTypeNumber) == TagTypeNumber; #else return rawValue(v1) & rawValue(v2) & TagTypeNumber; #endif } static double toDouble(JSValue); static bool toBoolean(JSValue); static bool getUInt32(JSValue, uint32_t&); static bool getTruncatedInt32(JSValue, int32_t&); static bool getTruncatedUInt32(JSValue, uint32_t&); static int32_t getTruncatedInt32(JSValue); static uint32_t getTruncatedUInt32(JSValue); static JSValue trueImmediate(); static JSValue falseImmediate(); static JSValue undefinedImmediate(); static JSValue nullImmediate(); static JSValue zeroImmediate(); static JSValue oneImmediate(); private: #if USE(JSVALUE64) static const int minImmediateInt = ((-INT_MAX) - 1); static const int maxImmediateInt = INT_MAX; #else static const int minImmediateInt = ((-INT_MAX) - 1) >> IntegerPayloadShift; static const int maxImmediateInt = INT_MAX >> IntegerPayloadShift; #endif static const unsigned maxImmediateUInt = maxImmediateInt; static ALWAYS_INLINE JSValue makeValue(intptr_t integer) { return JSValue::makeImmediate(integer); } // With USE(JSVALUE64) we want the argument to be zero extended, so the // integer doesn't interfere with the tag bits in the upper word. In the default encoding, // if intptr_t id larger then int32_t we sign extend the value through the upper word. #if USE(JSVALUE64) static ALWAYS_INLINE JSValue makeInt(uint32_t value) #else static ALWAYS_INLINE JSValue makeInt(int32_t value) #endif { return makeValue((static_cast<intptr_t>(value) << IntegerPayloadShift) | TagTypeNumber); } #if USE(JSVALUE64) static ALWAYS_INLINE JSValue makeDouble(double value) { return makeValue(reinterpretDoubleToIntptr(value) + DoubleEncodeOffset); } #endif static ALWAYS_INLINE JSValue makeBool(bool b) { return makeValue((static_cast<intptr_t>(b) << ExtendedPayloadShift) | FullTagTypeBool); } static ALWAYS_INLINE JSValue makeUndefined() { return makeValue(FullTagTypeUndefined); } static ALWAYS_INLINE JSValue makeNull() { return makeValue(FullTagTypeNull); } template<typename T> static JSValue fromNumberOutsideIntegerRange(T); #if USE(JSVALUE64) static ALWAYS_INLINE double doubleValue(JSValue v) { return reinterpretIntptrToDouble(rawValue(v) - DoubleEncodeOffset); } #endif static ALWAYS_INLINE int32_t intValue(JSValue v) { return static_cast<int32_t>(rawValue(v) >> IntegerPayloadShift); } static ALWAYS_INLINE uint32_t uintValue(JSValue v) { return static_cast<uint32_t>(rawValue(v) >> IntegerPayloadShift); } static ALWAYS_INLINE bool boolValue(JSValue v) { return rawValue(v) & ExtendedPayloadBitBoolValue; } static ALWAYS_INLINE intptr_t rawValue(JSValue v) { return v.immediateValue(); } }; ALWAYS_INLINE JSValue JSImmediate::trueImmediate() { return makeBool(true); } ALWAYS_INLINE JSValue JSImmediate::falseImmediate() { return makeBool(false); } ALWAYS_INLINE JSValue JSImmediate::undefinedImmediate() { return makeUndefined(); } ALWAYS_INLINE JSValue JSImmediate::nullImmediate() { return makeNull(); } ALWAYS_INLINE JSValue JSImmediate::zeroImmediate() { return makeInt(0); } ALWAYS_INLINE JSValue JSImmediate::oneImmediate() { return makeInt(1); } #if USE(JSVALUE64) inline bool doubleToBoolean(double value) { return value < 0.0 || value > 0.0; } ALWAYS_INLINE bool JSImmediate::toBoolean(JSValue v) { ASSERT(isImmediate(v)); return isNumber(v) ? isIntegerNumber(v) ? v != zeroImmediate() : doubleToBoolean(doubleValue(v)) : v == trueImmediate(); } #else ALWAYS_INLINE bool JSImmediate::toBoolean(JSValue v) { ASSERT(isImmediate(v)); return isIntegerNumber(v) ? v != zeroImmediate() : v == trueImmediate(); } #endif ALWAYS_INLINE uint32_t JSImmediate::getTruncatedUInt32(JSValue v) { // FIXME: should probably be asserting isPositiveIntegerNumber here. ASSERT(isIntegerNumber(v)); return intValue(v); } #if USE(JSVALUE64) template<typename T> inline JSValue JSImmediate::fromNumberOutsideIntegerRange(T value) { return makeDouble(static_cast<double>(value)); } #else template<typename T> inline JSValue JSImmediate::fromNumberOutsideIntegerRange(T) { return JSValue(); } #endif ALWAYS_INLINE JSValue JSImmediate::from(char i) { return makeInt(i); } ALWAYS_INLINE JSValue JSImmediate::from(signed char i) { return makeInt(i); } ALWAYS_INLINE JSValue JSImmediate::from(unsigned char i) { return makeInt(i); } ALWAYS_INLINE JSValue JSImmediate::from(short i) { return makeInt(i); } ALWAYS_INLINE JSValue JSImmediate::from(unsigned short i) { return makeInt(i); } ALWAYS_INLINE JSValue JSImmediate::from(int i) { #if !USE(JSVALUE64) if ((i < minImmediateInt) | (i > maxImmediateInt)) return fromNumberOutsideIntegerRange(i); #endif return makeInt(i); } ALWAYS_INLINE JSValue JSImmediate::from(unsigned i) { if (i > maxImmediateUInt) return fromNumberOutsideIntegerRange(i); return makeInt(i); } ALWAYS_INLINE JSValue JSImmediate::from(long i) { if ((i < minImmediateInt) | (i > maxImmediateInt)) return fromNumberOutsideIntegerRange(i); return makeInt(i); } ALWAYS_INLINE JSValue JSImmediate::from(unsigned long i) { if (i > maxImmediateUInt) return fromNumberOutsideIntegerRange(i); return makeInt(i); } ALWAYS_INLINE JSValue JSImmediate::from(long long i) { if ((i < minImmediateInt) | (i > maxImmediateInt)) return JSValue(); return makeInt(static_cast<intptr_t>(i)); } ALWAYS_INLINE JSValue JSImmediate::from(unsigned long long i) { if (i > maxImmediateUInt) return fromNumberOutsideIntegerRange(i); return makeInt(static_cast<intptr_t>(i)); } ALWAYS_INLINE JSValue JSImmediate::from(double d) { const int intVal = static_cast<int>(d); // Check for data loss from conversion to int. if (intVal != d || (!intVal && signbit(d))) return fromNumberOutsideIntegerRange(d); return from(intVal); } ALWAYS_INLINE int32_t JSImmediate::getTruncatedInt32(JSValue v) { ASSERT(isIntegerNumber(v)); return intValue(v); } ALWAYS_INLINE double JSImmediate::toDouble(JSValue v) { ASSERT(isImmediate(v)); if (isIntegerNumber(v)) return intValue(v); #if USE(JSVALUE64) if (isNumber(v)) { ASSERT(isDouble(v)); return doubleValue(v); } #else ASSERT(!isNumber(v)); #endif if (rawValue(v) == FullTagTypeUndefined) return nonInlineNaN(); ASSERT(JSImmediate::isBoolean(v) || (v == JSImmediate::nullImmediate())); return rawValue(v) >> ExtendedPayloadShift; } ALWAYS_INLINE bool JSImmediate::getUInt32(JSValue v, uint32_t& i) { i = uintValue(v); return isPositiveIntegerNumber(v); } ALWAYS_INLINE bool JSImmediate::getTruncatedInt32(JSValue v, int32_t& i) { i = intValue(v); return isIntegerNumber(v); } ALWAYS_INLINE bool JSImmediate::getTruncatedUInt32(JSValue v, uint32_t& i) { return getUInt32(v, i); } inline JSValue::JSValue(JSNullTag) { *this = JSImmediate::nullImmediate(); } inline JSValue::JSValue(JSUndefinedTag) { *this = JSImmediate::undefinedImmediate(); } inline JSValue::JSValue(JSTrueTag) { *this = JSImmediate::trueImmediate(); } inline JSValue::JSValue(JSFalseTag) { *this = JSImmediate::falseImmediate(); } inline bool JSValue::isUndefinedOrNull() const { return JSImmediate::isUndefinedOrNull(asValue()); } inline bool JSValue::isBoolean() const { return JSImmediate::isBoolean(asValue()); } inline bool JSValue::isTrue() const { return asValue() == JSImmediate::trueImmediate(); } inline bool JSValue::isFalse() const { return asValue() == JSImmediate::falseImmediate(); } inline bool JSValue::getBoolean(bool& v) const { if (JSImmediate::isBoolean(asValue())) { v = JSImmediate::toBoolean(asValue()); return true; } return false; } inline bool JSValue::getBoolean() const { return asValue() == jsBoolean(true); } inline bool JSValue::isCell() const { return !JSImmediate::isImmediate(asValue()); } inline bool JSValue::isInt32() const { return JSImmediate::isIntegerNumber(asValue()); } inline int32_t JSValue::asInt32() const { ASSERT(isInt32()); return JSImmediate::getTruncatedInt32(asValue()); } inline bool JSValue::isUInt32() const { return JSImmediate::isPositiveIntegerNumber(asValue()); } inline uint32_t JSValue::asUInt32() const { ASSERT(isUInt32()); return JSImmediate::getTruncatedUInt32(asValue()); } class JSFastMath { public: static ALWAYS_INLINE bool canDoFastBitwiseOperations(JSValue v1, JSValue v2) { return JSImmediate::areBothImmediateIntegerNumbers(v1, v2); } static ALWAYS_INLINE JSValue equal(JSValue v1, JSValue v2) { ASSERT(canDoFastBitwiseOperations(v1, v2)); return jsBoolean(v1 == v2); } static ALWAYS_INLINE JSValue notEqual(JSValue v1, JSValue v2) { ASSERT(canDoFastBitwiseOperations(v1, v2)); return jsBoolean(v1 != v2); } static ALWAYS_INLINE JSValue andImmediateNumbers(JSValue v1, JSValue v2) { ASSERT(canDoFastBitwiseOperations(v1, v2)); return JSImmediate::makeValue(JSImmediate::rawValue(v1) & JSImmediate::rawValue(v2)); } static ALWAYS_INLINE JSValue xorImmediateNumbers(JSValue v1, JSValue v2) { ASSERT(canDoFastBitwiseOperations(v1, v2)); return JSImmediate::makeValue((JSImmediate::rawValue(v1) ^ JSImmediate::rawValue(v2)) | JSImmediate::TagTypeNumber); } static ALWAYS_INLINE JSValue orImmediateNumbers(JSValue v1, JSValue v2) { ASSERT(canDoFastBitwiseOperations(v1, v2)); return JSImmediate::makeValue(JSImmediate::rawValue(v1) | JSImmediate::rawValue(v2)); } static ALWAYS_INLINE bool canDoFastRshift(JSValue v1, JSValue v2) { return JSImmediate::areBothImmediateIntegerNumbers(v1, v2); } static ALWAYS_INLINE bool canDoFastUrshift(JSValue v1, JSValue v2) { return JSImmediate::areBothImmediateIntegerNumbers(v1, v2) && !(JSImmediate::rawValue(v1) & JSImmediate::signBit); } static ALWAYS_INLINE JSValue rightShiftImmediateNumbers(JSValue val, JSValue shift) { ASSERT(canDoFastRshift(val, shift) || canDoFastUrshift(val, shift)); #if USE(JSVALUE64) return JSImmediate::makeValue(static_cast<intptr_t>(static_cast<uint32_t>(static_cast<int32_t>(JSImmediate::rawValue(val)) >> ((JSImmediate::rawValue(shift) >> JSImmediate::IntegerPayloadShift) & 0x1f))) | JSImmediate::TagTypeNumber); #else return JSImmediate::makeValue((JSImmediate::rawValue(val) >> ((JSImmediate::rawValue(shift) >> JSImmediate::IntegerPayloadShift) & 0x1f)) | JSImmediate::TagTypeNumber); #endif } static ALWAYS_INLINE bool canDoFastAdditiveOperations(JSValue v) { // Number is non-negative and an operation involving two of these can't overflow. // Checking for allowed negative numbers takes more time than it's worth on SunSpider. return (JSImmediate::rawValue(v) & (JSImmediate::TagTypeNumber + (JSImmediate::signBit | (JSImmediate::signBit >> 1)))) == JSImmediate::TagTypeNumber; } static ALWAYS_INLINE bool canDoFastAdditiveOperations(JSValue v1, JSValue v2) { // Number is non-negative and an operation involving two of these can't overflow. // Checking for allowed negative numbers takes more time than it's worth on SunSpider. return canDoFastAdditiveOperations(v1) && canDoFastAdditiveOperations(v2); } static ALWAYS_INLINE JSValue addImmediateNumbers(JSValue v1, JSValue v2) { ASSERT(canDoFastAdditiveOperations(v1, v2)); return JSImmediate::makeValue(JSImmediate::rawValue(v1) + JSImmediate::rawValue(v2) - JSImmediate::TagTypeNumber); } static ALWAYS_INLINE JSValue subImmediateNumbers(JSValue v1, JSValue v2) { ASSERT(canDoFastAdditiveOperations(v1, v2)); return JSImmediate::makeValue(JSImmediate::rawValue(v1) - JSImmediate::rawValue(v2) + JSImmediate::TagTypeNumber); } static ALWAYS_INLINE JSValue incImmediateNumber(JSValue v) { ASSERT(canDoFastAdditiveOperations(v)); return JSImmediate::makeValue(JSImmediate::rawValue(v) + (1 << JSImmediate::IntegerPayloadShift)); } static ALWAYS_INLINE JSValue decImmediateNumber(JSValue v) { ASSERT(canDoFastAdditiveOperations(v)); return JSImmediate::makeValue(JSImmediate::rawValue(v) - (1 << JSImmediate::IntegerPayloadShift)); } }; } // namespace JSC #endif // !USE(JSVALUE32_64) #endif // JSImmediate_h