This repository was archived by the owner on Jul 11, 2025. It is now read-only.
forked from phoboslab/JavaScriptCore-iOS
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathGetByIdStatus.cpp
More file actions
305 lines (259 loc) · 11.4 KB
/
GetByIdStatus.cpp
File metadata and controls
305 lines (259 loc) · 11.4 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
298
299
300
301
302
303
304
/*
* Copyright (C) 2012, 2013 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``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 INC. OR
* 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.
*/
#include "config.h"
#include "GetByIdStatus.h"
#include "CodeBlock.h"
#include "JSScope.h"
#include "LLIntData.h"
#include "LowLevelInterpreter.h"
#include "Operations.h"
namespace JSC {
GetByIdStatus GetByIdStatus::computeFromLLInt(CodeBlock* profiledBlock, unsigned bytecodeIndex, StringImpl* uid)
{
UNUSED_PARAM(profiledBlock);
UNUSED_PARAM(bytecodeIndex);
UNUSED_PARAM(uid);
#if ENABLE(LLINT)
Instruction* instruction = profiledBlock->instructions().begin() + bytecodeIndex;
if (instruction[0].u.opcode == LLInt::getOpcode(llint_op_get_array_length))
return GetByIdStatus(NoInformation, false);
Structure* structure = instruction[4].u.structure.get();
if (!structure)
return GetByIdStatus(NoInformation, false);
if (structure->takesSlowPathInDFGForImpureProperty())
return GetByIdStatus(NoInformation, false);
unsigned attributesIgnored;
JSCell* specificValue;
PropertyOffset offset = structure->getConcurrently(
*profiledBlock->vm(), uid, attributesIgnored, specificValue);
if (structure->isDictionary())
specificValue = 0;
if (!isValidOffset(offset))
return GetByIdStatus(NoInformation, false);
return GetByIdStatus(Simple, false, StructureSet(structure), offset, specificValue);
#else
return GetByIdStatus(NoInformation, false);
#endif
}
void GetByIdStatus::computeForChain(GetByIdStatus& result, CodeBlock* profiledBlock, StringImpl* uid)
{
#if ENABLE(JIT) && ENABLE(VALUE_PROFILER)
// Validate the chain. If the chain is invalid, then currently the best thing
// we can do is to assume that TakesSlow is true. In the future, it might be
// worth exploring reifying the structure chain from the structure we've got
// instead of using the one from the cache, since that will do the right things
// if the structure chain has changed. But that may be harder, because we may
// then end up having a different type of access altogether. And it currently
// does not appear to be worth it to do so -- effectively, the heuristic we
// have now is that if the structure chain has changed between when it was
// cached on in the baseline JIT and when the DFG tried to inline the access,
// then we fall back on a polymorphic access.
if (!result.m_chain->isStillValid())
return;
if (result.m_chain->head()->takesSlowPathInDFGForImpureProperty())
return;
size_t chainSize = result.m_chain->size();
for (size_t i = 0; i < chainSize; i++) {
if (result.m_chain->at(i)->takesSlowPathInDFGForImpureProperty())
return;
}
JSObject* currentObject = result.m_chain->terminalPrototype();
Structure* currentStructure = result.m_chain->last();
ASSERT_UNUSED(currentObject, currentObject);
unsigned attributesIgnored;
JSCell* specificValue;
result.m_offset = currentStructure->getConcurrently(
*profiledBlock->vm(), uid, attributesIgnored, specificValue);
if (currentStructure->isDictionary())
specificValue = 0;
if (!isValidOffset(result.m_offset))
return;
result.m_structureSet.add(result.m_chain->head());
result.m_specificValue = JSValue(specificValue);
#else
UNUSED_PARAM(result);
UNUSED_PARAM(profiledBlock);
UNUSED_PARAM(uid);
UNREACHABLE_FOR_PLATFORM();
#endif
}
GetByIdStatus GetByIdStatus::computeFor(CodeBlock* profiledBlock, StubInfoMap& map, unsigned bytecodeIndex, StringImpl* uid)
{
ConcurrentJITLocker locker(profiledBlock->m_lock);
UNUSED_PARAM(profiledBlock);
UNUSED_PARAM(bytecodeIndex);
UNUSED_PARAM(uid);
#if ENABLE(JIT) && ENABLE(VALUE_PROFILER)
StructureStubInfo* stubInfo = map.get(CodeOrigin(bytecodeIndex));
if (!stubInfo || !stubInfo->seen)
return computeFromLLInt(profiledBlock, bytecodeIndex, uid);
if (stubInfo->resetByGC)
return GetByIdStatus(TakesSlowPath, true);
PolymorphicAccessStructureList* list;
int listSize;
switch (stubInfo->accessType) {
case access_get_by_id_self_list:
list = stubInfo->u.getByIdSelfList.structureList;
listSize = stubInfo->u.getByIdSelfList.listSize;
break;
case access_get_by_id_proto_list:
list = stubInfo->u.getByIdProtoList.structureList;
listSize = stubInfo->u.getByIdProtoList.listSize;
break;
default:
list = 0;
listSize = 0;
break;
}
for (int i = 0; i < listSize; ++i) {
if (!list->list[i].isDirect)
return GetByIdStatus(MakesCalls, true);
}
// Next check if it takes slow case, in which case we want to be kind of careful.
if (profiledBlock->likelyToTakeSlowCase(bytecodeIndex))
return GetByIdStatus(TakesSlowPath, true);
// Finally figure out if we can derive an access strategy.
GetByIdStatus result;
result.m_wasSeenInJIT = true; // This is interesting for bytecode dumping only.
switch (stubInfo->accessType) {
case access_unset:
return computeFromLLInt(profiledBlock, bytecodeIndex, uid);
case access_get_by_id_self: {
Structure* structure = stubInfo->u.getByIdSelf.baseObjectStructure.get();
if (structure->takesSlowPathInDFGForImpureProperty())
return GetByIdStatus(TakesSlowPath, true);
unsigned attributesIgnored;
JSCell* specificValue;
result.m_offset = structure->getConcurrently(
*profiledBlock->vm(), uid, attributesIgnored, specificValue);
if (structure->isDictionary())
specificValue = 0;
if (isValidOffset(result.m_offset)) {
result.m_structureSet.add(structure);
result.m_specificValue = JSValue(specificValue);
}
if (isValidOffset(result.m_offset))
ASSERT(result.m_structureSet.size());
break;
}
case access_get_by_id_self_list: {
for (int i = 0; i < listSize; ++i) {
ASSERT(list->list[i].isDirect);
Structure* structure = list->list[i].base.get();
if (structure->takesSlowPathInDFGForImpureProperty())
return GetByIdStatus(TakesSlowPath, true);
if (result.m_structureSet.contains(structure))
continue;
unsigned attributesIgnored;
JSCell* specificValue;
PropertyOffset myOffset = structure->getConcurrently(
*profiledBlock->vm(), uid, attributesIgnored, specificValue);
if (structure->isDictionary())
specificValue = 0;
if (!isValidOffset(myOffset)) {
result.m_offset = invalidOffset;
break;
}
if (!i) {
result.m_offset = myOffset;
result.m_specificValue = JSValue(specificValue);
} else if (result.m_offset != myOffset) {
result.m_offset = invalidOffset;
break;
} else if (result.m_specificValue != JSValue(specificValue))
result.m_specificValue = JSValue();
result.m_structureSet.add(structure);
}
if (isValidOffset(result.m_offset))
ASSERT(result.m_structureSet.size());
break;
}
case access_get_by_id_proto: {
if (!stubInfo->u.getByIdProto.isDirect)
return GetByIdStatus(MakesCalls, true);
result.m_chain = adoptRef(new IntendedStructureChain(
profiledBlock,
stubInfo->u.getByIdProto.baseObjectStructure.get(),
stubInfo->u.getByIdProto.prototypeStructure.get()));
computeForChain(result, profiledBlock, uid);
break;
}
case access_get_by_id_chain: {
if (!stubInfo->u.getByIdChain.isDirect)
return GetByIdStatus(MakesCalls, true);
result.m_chain = adoptRef(new IntendedStructureChain(
profiledBlock,
stubInfo->u.getByIdChain.baseObjectStructure.get(),
stubInfo->u.getByIdChain.chain.get(),
stubInfo->u.getByIdChain.count));
computeForChain(result, profiledBlock, uid);
break;
}
default:
ASSERT(!isValidOffset(result.m_offset));
break;
}
if (!isValidOffset(result.m_offset)) {
result.m_state = TakesSlowPath;
result.m_structureSet.clear();
result.m_chain.clear();
result.m_specificValue = JSValue();
} else
result.m_state = Simple;
return result;
#else // ENABLE(JIT)
UNUSED_PARAM(map);
return GetByIdStatus(NoInformation, false);
#endif // ENABLE(JIT)
}
GetByIdStatus GetByIdStatus::computeFor(VM& vm, Structure* structure, StringImpl* uid)
{
// For now we only handle the super simple self access case. We could handle the
// prototype case in the future.
if (!structure)
return GetByIdStatus(TakesSlowPath);
if (toUInt32FromStringImpl(uid) != PropertyName::NotAnIndex)
return GetByIdStatus(TakesSlowPath);
if (structure->typeInfo().overridesGetOwnPropertySlot() && structure->typeInfo().type() != GlobalObjectType)
return GetByIdStatus(TakesSlowPath);
if (!structure->propertyAccessesAreCacheable())
return GetByIdStatus(TakesSlowPath);
GetByIdStatus result;
result.m_wasSeenInJIT = false; // To my knowledge nobody that uses computeFor(VM&, Structure*, StringImpl*) reads this field, but I might as well be honest: no, it wasn't seen in the JIT, since I computed it statically.
unsigned attributes;
JSCell* specificValue;
result.m_offset = structure->getConcurrently(vm, uid, attributes, specificValue);
if (!isValidOffset(result.m_offset))
return GetByIdStatus(TakesSlowPath); // It's probably a prototype lookup. Give up on life for now, even though we could totally be way smarter about it.
if (attributes & Accessor)
return GetByIdStatus(MakesCalls);
if (structure->isDictionary())
specificValue = 0;
result.m_structureSet.add(structure);
result.m_specificValue = JSValue(specificValue);
result.m_state = Simple;
return result;
}
} // namespace JSC