2
* Copyright (C) 2019 Apple Inc. All rights reserved.
4
* Redistribution and use in source and binary forms, with or without
5
* modification, are permitted provided that the following conditions
7
* 1. Redistributions of source code must retain the above copyright
8
* notice, this list of conditions and the following disclaimer.
9
* 2. Redistributions in binary form must reproduce the above copyright
10
* notice, this list of conditions and the following disclaimer in the
11
* documentation and/or other materials provided with the distribution.
13
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28
#include <wtf/HashTraits.h>
29
#include <wtf/MathExtras.h>
39
BytecodeIndex() = default;
40
BytecodeIndex(WTF::HashTableDeletedValueType)
41
: m_packedBits(deletedValue().asBits())
45
explicit BytecodeIndex(uint32_t bytecodeOffset, uint8_t checkpoint = 0)
46
: m_packedBits(pack(bytecodeOffset, checkpoint))
51
static constexpr uint32_t numberOfCheckpoints = 4;
52
static_assert(hasOneBitSet(numberOfCheckpoints), "numberOfCheckpoints should be a power of 2");
53
static constexpr uint32_t checkpointMask = numberOfCheckpoints - 1;
54
static constexpr uint32_t checkpointShift = WTF::getMSBSetConstexpr(numberOfCheckpoints);
56
uint32_t offset() const { return m_packedBits >> checkpointShift; }
57
uint8_t checkpoint() const { return m_packedBits & checkpointMask; }
58
uint32_t asBits() const { return m_packedBits; }
60
unsigned hash() const { return WTF::intHash(m_packedBits); }
61
static BytecodeIndex deletedValue() { return fromBits(invalidOffset - 1); }
62
bool isHashTableDeletedValue() const { return *this == deletedValue(); }
64
static BytecodeIndex fromBits(uint32_t bits);
66
// Comparison operators.
67
explicit operator bool() const { return m_packedBits != invalidOffset && m_packedBits != deletedValue().offset(); }
68
bool operator ==(const BytecodeIndex& other) const { return asBits() == other.asBits(); }
69
bool operator !=(const BytecodeIndex& other) const { return !(*this == other); }
71
bool operator <(const BytecodeIndex& other) const { return asBits() < other.asBits(); }
72
bool operator >(const BytecodeIndex& other) const { return asBits() > other.asBits(); }
73
bool operator <=(const BytecodeIndex& other) const { return asBits() <= other.asBits(); }
74
bool operator >=(const BytecodeIndex& other) const { return asBits() >= other.asBits(); }
77
void dump(WTF::PrintStream&) const;
80
static constexpr uint32_t invalidOffset = std::numeric_limits<uint32_t>::max();
82
static uint32_t pack(uint32_t bytecodeIndex, uint8_t checkpoint);
84
uint32_t m_packedBits { invalidOffset };
87
inline uint32_t BytecodeIndex::pack(uint32_t bytecodeIndex, uint8_t checkpoint)
89
ASSERT(checkpoint < numberOfCheckpoints);
90
ASSERT((bytecodeIndex << checkpointShift) >> checkpointShift == bytecodeIndex);
91
return bytecodeIndex << checkpointShift | checkpoint;
94
inline BytecodeIndex BytecodeIndex::fromBits(uint32_t bits)
97
result.m_packedBits = bits;
101
struct BytecodeIndexHash {
102
static unsigned hash(const BytecodeIndex& key) { return key.hash(); }
103
static bool equal(const BytecodeIndex& a, const BytecodeIndex& b) { return a == b; }
104
static constexpr bool safeToCompareToEmptyOrDeleted = true;
111
template<typename T> struct DefaultHash;
112
template<> struct DefaultHash<JSC::BytecodeIndex> {
113
typedef JSC::BytecodeIndexHash Hash;
116
template<typename T> struct HashTraits;
117
template<> struct HashTraits<JSC::BytecodeIndex> : SimpleClassHashTraits<JSC::BytecodeIndex> {
118
static constexpr bool emptyValueIsZero = false;