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
|
/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <ctime>
#include "object.h"
#include "art_field.h"
#include "art_field-inl.h"
#include "array-inl.h"
#include "class.h"
#include "class-inl.h"
#include "class_linker-inl.h"
#include "dex_file-inl.h"
#include "gc/accounting/card_table-inl.h"
#include "gc/heap.h"
#include "iftable-inl.h"
#include "monitor.h"
#include "object-inl.h"
#include "object_array-inl.h"
#include "runtime.h"
#include "handle_scope-inl.h"
#include "throwable.h"
#include "well_known_classes.h"
namespace art {
namespace mirror {
Atomic<uint32_t> Object::hash_code_seed(987654321U + std::time(nullptr));
class CopyReferenceFieldsWithReadBarrierVisitor {
public:
explicit CopyReferenceFieldsWithReadBarrierVisitor(Object* dest_obj)
: dest_obj_(dest_obj) {}
void operator()(Object* obj, MemberOffset offset, bool /* is_static */) const
ALWAYS_INLINE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
// GetFieldObject() contains a RB.
Object* ref = obj->GetFieldObject<Object>(offset);
// No WB here as a large object space does not have a card table
// coverage. Instead, cards will be marked separately.
dest_obj_->SetFieldObjectWithoutWriteBarrier<false, false>(offset, ref);
}
void operator()(mirror::Class* klass, mirror::Reference* ref) const
ALWAYS_INLINE SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
// Copy java.lang.ref.Reference.referent which isn't visited in
// Object::VisitReferences().
DCHECK(klass->IsTypeOfReferenceClass());
this->operator()(ref, mirror::Reference::ReferentOffset(), false);
}
private:
Object* const dest_obj_;
};
Object* Object::CopyObject(Thread* self, mirror::Object* dest, mirror::Object* src,
size_t num_bytes) {
// Copy instance data. We assume memcpy copies by words.
// TODO: expose and use move32.
uint8_t* src_bytes = reinterpret_cast<uint8_t*>(src);
uint8_t* dst_bytes = reinterpret_cast<uint8_t*>(dest);
size_t offset = sizeof(Object);
memcpy(dst_bytes + offset, src_bytes + offset, num_bytes - offset);
if (kUseReadBarrier) {
// We need a RB here. After the memcpy that covers the whole
// object above, copy references fields one by one again with a
// RB. TODO: Optimize this later?
CopyReferenceFieldsWithReadBarrierVisitor visitor(dest);
src->VisitReferences<true>(visitor, visitor);
}
gc::Heap* heap = Runtime::Current()->GetHeap();
// Perform write barriers on copied object references.
Class* c = src->GetClass();
if (c->IsArrayClass()) {
if (!c->GetComponentType()->IsPrimitive()) {
ObjectArray<Object>* array = dest->AsObjectArray<Object>();
heap->WriteBarrierArray(dest, 0, array->GetLength());
}
} else {
heap->WriteBarrierEveryFieldOf(dest);
}
if (c->IsFinalizable()) {
heap->AddFinalizerReference(self, &dest);
}
return dest;
}
// An allocation pre-fence visitor that copies the object.
class CopyObjectVisitor {
public:
explicit CopyObjectVisitor(Thread* self, Handle<Object>* orig, size_t num_bytes)
: self_(self), orig_(orig), num_bytes_(num_bytes) {
}
void operator()(Object* obj, size_t usable_size) const
SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
UNUSED(usable_size);
Object::CopyObject(self_, obj, orig_->Get(), num_bytes_);
}
private:
Thread* const self_;
Handle<Object>* const orig_;
const size_t num_bytes_;
DISALLOW_COPY_AND_ASSIGN(CopyObjectVisitor);
};
Object* Object::Clone(Thread* self) {
CHECK(!IsClass()) << "Can't clone classes.";
// Object::SizeOf gets the right size even if we're an array. Using c->AllocObject() here would
// be wrong.
gc::Heap* heap = Runtime::Current()->GetHeap();
size_t num_bytes = SizeOf();
StackHandleScope<1> hs(self);
Handle<Object> this_object(hs.NewHandle(this));
Object* copy;
CopyObjectVisitor visitor(self, &this_object, num_bytes);
if (heap->IsMovableObject(this)) {
copy = heap->AllocObject<true>(self, GetClass(), num_bytes, visitor);
} else {
copy = heap->AllocNonMovableObject<true>(self, GetClass(), num_bytes, visitor);
}
return copy;
}
uint32_t Object::GenerateIdentityHashCode() {
uint32_t expected_value, new_value;
do {
expected_value = hash_code_seed.LoadRelaxed();
new_value = expected_value * 1103515245 + 12345;
} while (!hash_code_seed.CompareExchangeWeakRelaxed(expected_value, new_value) ||
(expected_value & LockWord::kHashMask) == 0);
return expected_value & LockWord::kHashMask;
}
void Object::SetHashCodeSeed(uint32_t new_seed) {
hash_code_seed.StoreRelaxed(new_seed);
}
int32_t Object::IdentityHashCode() const {
mirror::Object* current_this = const_cast<mirror::Object*>(this);
while (true) {
LockWord lw = current_this->GetLockWord(false);
switch (lw.GetState()) {
case LockWord::kUnlocked: {
// Try to compare and swap in a new hash, if we succeed we will return the hash on the next
// loop iteration.
LockWord hash_word = LockWord::FromHashCode(GenerateIdentityHashCode(),
lw.ReadBarrierState());
DCHECK_EQ(hash_word.GetState(), LockWord::kHashCode);
if (const_cast<Object*>(this)->CasLockWordWeakRelaxed(lw, hash_word)) {
return hash_word.GetHashCode();
}
break;
}
case LockWord::kThinLocked: {
// Inflate the thin lock to a monitor and stick the hash code inside of the monitor. May
// fail spuriously.
Thread* self = Thread::Current();
StackHandleScope<1> hs(self);
Handle<mirror::Object> h_this(hs.NewHandle(current_this));
Monitor::InflateThinLocked(self, h_this, lw, GenerateIdentityHashCode());
// A GC may have occurred when we switched to kBlocked.
current_this = h_this.Get();
break;
}
case LockWord::kFatLocked: {
// Already inflated, return the has stored in the monitor.
Monitor* monitor = lw.FatLockMonitor();
DCHECK(monitor != nullptr);
return monitor->GetHashCode();
}
case LockWord::kHashCode: {
return lw.GetHashCode();
}
default: {
LOG(FATAL) << "Invalid state during hashcode " << lw.GetState();
break;
}
}
}
UNREACHABLE();
}
void Object::CheckFieldAssignmentImpl(MemberOffset field_offset, Object* new_value) {
Class* c = GetClass();
Runtime* runtime = Runtime::Current();
if (runtime->GetClassLinker() == nullptr || !runtime->IsStarted() ||
!runtime->GetHeap()->IsObjectValidationEnabled() || !c->IsResolved()) {
return;
}
for (Class* cur = c; cur != NULL; cur = cur->GetSuperClass()) {
ArtField* fields = cur->GetIFields();
for (size_t i = 0, count = cur->NumInstanceFields(); i < count; ++i) {
StackHandleScope<1> hs(Thread::Current());
Handle<Object> h_object(hs.NewHandle(new_value));
ArtField* field = &fields[i];
if (field->GetOffset().Int32Value() == field_offset.Int32Value()) {
CHECK_NE(field->GetTypeAsPrimitiveType(), Primitive::kPrimNot);
// TODO: resolve the field type for moving GC.
mirror::Class* field_type = field->GetType<!kMovingCollector>();
if (field_type != nullptr) {
CHECK(field_type->IsAssignableFrom(new_value->GetClass()));
}
return;
}
}
}
if (c->IsArrayClass()) {
// Bounds and assign-ability done in the array setter.
return;
}
if (IsClass()) {
ArtField* fields = AsClass()->GetSFields();
for (size_t i = 0, count = AsClass()->NumStaticFields(); i < count; ++i) {
ArtField* field = &fields[i];
if (field->GetOffset().Int32Value() == field_offset.Int32Value()) {
CHECK_NE(field->GetTypeAsPrimitiveType(), Primitive::kPrimNot);
// TODO: resolve the field type for moving GC.
mirror::Class* field_type = field->GetType<!kMovingCollector>();
if (field_type != nullptr) {
CHECK(field_type->IsAssignableFrom(new_value->GetClass()));
}
return;
}
}
}
LOG(FATAL) << "Failed to find field for assignment to " << reinterpret_cast<void*>(this)
<< " of type " << PrettyDescriptor(c) << " at offset " << field_offset;
UNREACHABLE();
}
} // namespace mirror
} // namespace art
|
