Repository navigation
Expand file tree
/
Copy pathCompactJITCodeMap.h
More file actions
297 lines (256 loc) · 9.18 KB
/
Copy pathCompactJITCodeMap.h
File metadata and controls
297 lines (256 loc) · 9.18 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
/*
* Copyright (C) 2011 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Apple Inc. ("Apple") nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CompactJITCodeMap_h
#define CompactJITCodeMap_h
#include <wtf/Assertions.h>
#include <wtf/FastMalloc.h>
#include <wtf/FastMalloc.h>
#include <wtf/OwnPtr.h>
#include <wtf/PassOwnPtr.h>
#include <wtf/Vector.h>
namespace JSC {
// Gives you a compressed map between between bytecode indices and machine code
// entry points. The compression simply tries to use either 1, 2, or 4 bytes for
// any given offset. The largest offset that can be stored is 2^30.
// Example use:
//
// CompactJITCodeMap::Encoder encoder(map);
// encoder.append(a, b);
// encoder.append(c, d); // preconditions: c >= a, d >= b
// OwnPtr<CompactJITCodeMap> map = encoder.finish();
//
// At some later time:
//
// Vector<BytecodeAndMachineOffset> decoded;
// map->decode(decoded);
struct BytecodeAndMachineOffset {
BytecodeAndMachineOffset() { }
BytecodeAndMachineOffset(unsigned bytecodeIndex, unsigned machineCodeOffset)
: m_bytecodeIndex(bytecodeIndex)
, m_machineCodeOffset(machineCodeOffset)
{
}
unsigned m_bytecodeIndex;
unsigned m_machineCodeOffset;
static inline unsigned getBytecodeIndex(BytecodeAndMachineOffset* mapping)
{
return mapping->m_bytecodeIndex;
}
static inline unsigned getMachineCodeOffset(BytecodeAndMachineOffset* mapping)
{
return mapping->m_machineCodeOffset;
}
};
class CompactJITCodeMap {
WTF_MAKE_FAST_ALLOCATED;
public:
~CompactJITCodeMap()
{
if (m_buffer)
fastFree(m_buffer);
}
unsigned numberOfEntries() const
{
return m_numberOfEntries;
}
void decode(Vector<BytecodeAndMachineOffset>& result) const;
private:
CompactJITCodeMap(uint8_t* buffer, unsigned size, unsigned numberOfEntries)
: m_buffer(buffer)
#if !ASSERT_DISABLED
, m_size(size)
#endif
, m_numberOfEntries(numberOfEntries)
{
UNUSED_PARAM(size);
}
uint8_t at(unsigned index) const
{
ASSERT(index < m_size);
return m_buffer[index];
}
unsigned decodeNumber(unsigned& index) const
{
uint8_t headValue = at(index++);
if (!(headValue & 128))
return headValue;
if (!(headValue & 64))
return (static_cast<unsigned>(headValue & ~128) << 8) | at(index++);
unsigned second = at(index++);
unsigned third = at(index++);
unsigned fourth = at(index++);
return (static_cast<unsigned>(headValue & ~(128 + 64)) << 24) | (second << 16) | (third << 8) | fourth;
}
uint8_t* m_buffer;
#if !ASSERT_DISABLED
unsigned m_size;
#endif
unsigned m_numberOfEntries;
public:
class Encoder {
WTF_MAKE_NONCOPYABLE(Encoder);
public:
Encoder();
~Encoder();
void ensureCapacityFor(unsigned numberOfEntriesToAdd);
void append(unsigned bytecodeIndex, unsigned machineCodeOffset);
PassOwnPtr<CompactJITCodeMap> finish();
private:
void appendByte(uint8_t value);
void encodeNumber(uint32_t value);
uint8_t* m_buffer;
unsigned m_size;
unsigned m_capacity;
unsigned m_numberOfEntries;
unsigned m_previousBytecodeIndex;
unsigned m_previousMachineCodeOffset;
};
class Decoder {
WTF_MAKE_NONCOPYABLE(Decoder);
public:
Decoder(const CompactJITCodeMap*);
unsigned numberOfEntriesRemaining() const;
void read(unsigned& bytecodeIndex, unsigned& machineCodeOffset);
private:
const CompactJITCodeMap* m_jitCodeMap;
unsigned m_previousBytecodeIndex;
unsigned m_previousMachineCodeOffset;
unsigned m_numberOfEntriesRemaining;
unsigned m_bufferIndex;
};
private:
friend class Encoder;
friend class Decoder;
};
inline void CompactJITCodeMap::decode(Vector<BytecodeAndMachineOffset>& result) const
{
Decoder decoder(this);
result.resize(decoder.numberOfEntriesRemaining());
for (unsigned i = 0; i < result.size(); ++i)
decoder.read(result[i].m_bytecodeIndex, result[i].m_machineCodeOffset);
ASSERT(!decoder.numberOfEntriesRemaining());
}
inline CompactJITCodeMap::Encoder::Encoder()
: m_buffer(0)
, m_size(0)
, m_capacity(0)
, m_numberOfEntries(0)
, m_previousBytecodeIndex(0)
, m_previousMachineCodeOffset(0)
{
}
inline CompactJITCodeMap::Encoder::~Encoder()
{
if (m_buffer)
fastFree(m_buffer);
}
inline void CompactJITCodeMap::Encoder::append(unsigned bytecodeIndex, unsigned machineCodeOffset)
{
ASSERT(bytecodeIndex >= m_previousBytecodeIndex);
ASSERT(machineCodeOffset >= m_previousMachineCodeOffset);
ensureCapacityFor(1);
encodeNumber(bytecodeIndex - m_previousBytecodeIndex);
encodeNumber(machineCodeOffset - m_previousMachineCodeOffset);
m_previousBytecodeIndex = bytecodeIndex;
m_previousMachineCodeOffset = machineCodeOffset;
m_numberOfEntries++;
}
inline PassOwnPtr<CompactJITCodeMap> CompactJITCodeMap::Encoder::finish()
{
m_capacity = m_size;
m_buffer = static_cast<uint8_t*>(fastRealloc(m_buffer, m_capacity));
OwnPtr<CompactJITCodeMap> result = adoptPtr(new CompactJITCodeMap(m_buffer, m_size, m_numberOfEntries));
m_buffer = 0;
m_size = 0;
m_capacity = 0;
m_numberOfEntries = 0;
m_previousBytecodeIndex = 0;
m_previousMachineCodeOffset = 0;
return result.release();
}
inline void CompactJITCodeMap::Encoder::appendByte(uint8_t value)
{
ASSERT(m_size + 1 <= m_capacity);
m_buffer[m_size++] = value;
}
inline void CompactJITCodeMap::Encoder::encodeNumber(uint32_t value)
{
ASSERT(m_size + 4 <= m_capacity);
ASSERT(value < (1 << 30));
if (value <= 127) {
uint8_t headValue = static_cast<uint8_t>(value);
ASSERT(!(headValue & 128));
appendByte(headValue);
} else if (value <= 16383) {
uint8_t headValue = static_cast<uint8_t>(value >> 8);
ASSERT(!(headValue & 128));
ASSERT(!(headValue & 64));
appendByte(headValue | 128);
appendByte(static_cast<uint8_t>(value));
} else {
uint8_t headValue = static_cast<uint8_t>(value >> 24);
ASSERT(!(headValue & 128));
ASSERT(!(headValue & 64));
appendByte(headValue | 128 | 64);
appendByte(static_cast<uint8_t>(value >> 16));
appendByte(static_cast<uint8_t>(value >> 8));
appendByte(static_cast<uint8_t>(value));
}
}
inline void CompactJITCodeMap::Encoder::ensureCapacityFor(unsigned numberOfEntriesToAdd)
{
unsigned capacityNeeded = m_size + numberOfEntriesToAdd * 2 * 4;
if (capacityNeeded > m_capacity) {
m_capacity = capacityNeeded * 2;
m_buffer = static_cast<uint8_t*>(fastRealloc(m_buffer, m_capacity));
}
}
inline CompactJITCodeMap::Decoder::Decoder(const CompactJITCodeMap* jitCodeMap)
: m_jitCodeMap(jitCodeMap)
, m_previousBytecodeIndex(0)
, m_previousMachineCodeOffset(0)
, m_numberOfEntriesRemaining(jitCodeMap->m_numberOfEntries)
, m_bufferIndex(0)
{
}
inline unsigned CompactJITCodeMap::Decoder::numberOfEntriesRemaining() const
{
ASSERT(m_numberOfEntriesRemaining || m_bufferIndex == m_jitCodeMap->m_size);
return m_numberOfEntriesRemaining;
}
inline void CompactJITCodeMap::Decoder::read(unsigned& bytecodeIndex, unsigned& machineCodeOffset)
{
ASSERT(numberOfEntriesRemaining());
m_previousBytecodeIndex += m_jitCodeMap->decodeNumber(m_bufferIndex);
m_previousMachineCodeOffset += m_jitCodeMap->decodeNumber(m_bufferIndex);
bytecodeIndex = m_previousBytecodeIndex;
machineCodeOffset = m_previousMachineCodeOffset;
m_numberOfEntriesRemaining--;
}
} // namespace JSC
#endif // CompactJITCodeMap_h