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Diffstat (limited to 'Source/JavaScriptCore/runtime/JSImmediate.h')
| -rw-r--r-- | Source/JavaScriptCore/runtime/JSImmediate.h | 568 |
1 files changed, 568 insertions, 0 deletions
diff --git a/Source/JavaScriptCore/runtime/JSImmediate.h b/Source/JavaScriptCore/runtime/JSImmediate.h new file mode 100644 index 0000000..68ba75c --- /dev/null +++ b/Source/JavaScriptCore/runtime/JSImmediate.h @@ -0,0 +1,568 @@ +/* + * 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 + +#if USE(JSVALUE64) + +#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 JSGlobalData; + class JSObject; + class UString; + + 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); + } + + /* + * 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 JSInterfaceJIT; + friend class SpecializedThunkJIT; + 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 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; + 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; + + static const int32_t IntegerPayloadShift = 0; + 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) + { + return (rawValue(v) & TagTypeNumber) == TagTypeNumber; + } + + static ALWAYS_INLINE bool isDouble(JSValue v) + { + return isNumber(v) && !isIntegerNumber(v); + } + + 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) + { + return (rawValue(v1) & rawValue(v2) & TagTypeNumber) == TagTypeNumber; + } + + 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: + static const int minImmediateInt = ((-INT_MAX) - 1); + static const int maxImmediateInt = INT_MAX; + 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. + static ALWAYS_INLINE JSValue makeInt(uint32_t value) + { + return makeValue((static_cast<intptr_t>(value) << IntegerPayloadShift) | TagTypeNumber); + } + + static ALWAYS_INLINE JSValue makeDouble(double value) + { + return makeValue(reinterpretDoubleToIntptr(value) + DoubleEncodeOffset); + } + + 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); + + static ALWAYS_INLINE double doubleValue(JSValue v) + { + return reinterpretIntptrToDouble(rawValue(v) - DoubleEncodeOffset); + } + + 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); } + + 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(); + } + + ALWAYS_INLINE uint32_t JSImmediate::getTruncatedUInt32(JSValue v) + { + // FIXME: should probably be asserting isPositiveIntegerNumber here. + ASSERT(isIntegerNumber(v)); + return intValue(v); + } + + template<typename T> + inline JSValue JSImmediate::fromNumberOutsideIntegerRange(T value) + { + return makeDouble(static_cast<double>(value)); + } + + 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) + { + 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 (isNumber(v)) { + ASSERT(isDouble(v)); + return doubleValue(v); + } + + 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()); + } + +} // namespace JSC + +#endif // USE(JSVALUE64) + +#endif // JSImmediate_h |