1 /*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <ctime>
18
19 #include "object.h"
20
21 #include "art_field.h"
22 #include "art_field-inl.h"
23 #include "array-inl.h"
24 #include "class.h"
25 #include "class-inl.h"
26 #include "class_linker-inl.h"
27 #include "dex_file-inl.h"
28 #include "gc/accounting/card_table-inl.h"
29 #include "gc/heap.h"
30 #include "iftable-inl.h"
31 #include "monitor.h"
32 #include "object-inl.h"
33 #include "object_array-inl.h"
34 #include "runtime.h"
35 #include "handle_scope-inl.h"
36 #include "throwable.h"
37 #include "well_known_classes.h"
38
39 namespace art {
40 namespace mirror {
41
42 Atomic<uint32_t> Object::hash_code_seed(987654321U + std::time(nullptr));
43
44 class CopyReferenceFieldsWithReadBarrierVisitor {
45 public:
CopyReferenceFieldsWithReadBarrierVisitor(Object * dest_obj)46 explicit CopyReferenceFieldsWithReadBarrierVisitor(Object* dest_obj)
47 : dest_obj_(dest_obj) {}
48
operator ()(Object * obj,MemberOffset offset,bool) const49 void operator()(Object* obj, MemberOffset offset, bool /* is_static */) const
50 ALWAYS_INLINE SHARED_REQUIRES(Locks::mutator_lock_) {
51 // GetFieldObject() contains a RB.
52 Object* ref = obj->GetFieldObject<Object>(offset);
53 // No WB here as a large object space does not have a card table
54 // coverage. Instead, cards will be marked separately.
55 dest_obj_->SetFieldObjectWithoutWriteBarrier<false, false>(offset, ref);
56 }
57
operator ()(mirror::Class * klass,mirror::Reference * ref) const58 void operator()(mirror::Class* klass, mirror::Reference* ref) const
59 ALWAYS_INLINE SHARED_REQUIRES(Locks::mutator_lock_) {
60 // Copy java.lang.ref.Reference.referent which isn't visited in
61 // Object::VisitReferences().
62 DCHECK(klass->IsTypeOfReferenceClass());
63 this->operator()(ref, mirror::Reference::ReferentOffset(), false);
64 }
65
66 // Unused since we don't copy class native roots.
VisitRootIfNonNull(mirror::CompressedReference<mirror::Object> * root ATTRIBUTE_UNUSED) const67 void VisitRootIfNonNull(mirror::CompressedReference<mirror::Object>* root ATTRIBUTE_UNUSED)
68 const {}
VisitRoot(mirror::CompressedReference<mirror::Object> * root ATTRIBUTE_UNUSED) const69 void VisitRoot(mirror::CompressedReference<mirror::Object>* root ATTRIBUTE_UNUSED) const {}
70
71 private:
72 Object* const dest_obj_;
73 };
74
CopyObject(Thread * self,mirror::Object * dest,mirror::Object * src,size_t num_bytes)75 Object* Object::CopyObject(Thread* self, mirror::Object* dest, mirror::Object* src,
76 size_t num_bytes) {
77 // Copy instance data. We assume memcpy copies by words.
78 // TODO: expose and use move32.
79 uint8_t* src_bytes = reinterpret_cast<uint8_t*>(src);
80 uint8_t* dst_bytes = reinterpret_cast<uint8_t*>(dest);
81 size_t offset = sizeof(Object);
82 memcpy(dst_bytes + offset, src_bytes + offset, num_bytes - offset);
83 if (kUseReadBarrier) {
84 // We need a RB here. After the memcpy that covers the whole
85 // object above, copy references fields one by one again with a
86 // RB. TODO: Optimize this later?
87 CopyReferenceFieldsWithReadBarrierVisitor visitor(dest);
88 src->VisitReferences(visitor, visitor);
89 }
90 gc::Heap* heap = Runtime::Current()->GetHeap();
91 // Perform write barriers on copied object references.
92 Class* c = src->GetClass();
93 if (c->IsArrayClass()) {
94 if (!c->GetComponentType()->IsPrimitive()) {
95 ObjectArray<Object>* array = dest->AsObjectArray<Object>();
96 heap->WriteBarrierArray(dest, 0, array->GetLength());
97 }
98 } else {
99 heap->WriteBarrierEveryFieldOf(dest);
100 }
101 if (c->IsFinalizable()) {
102 heap->AddFinalizerReference(self, &dest);
103 }
104 return dest;
105 }
106
107 // An allocation pre-fence visitor that copies the object.
108 class CopyObjectVisitor {
109 public:
CopyObjectVisitor(Thread * self,Handle<Object> * orig,size_t num_bytes)110 CopyObjectVisitor(Thread* self, Handle<Object>* orig, size_t num_bytes)
111 : self_(self), orig_(orig), num_bytes_(num_bytes) {
112 }
113
operator ()(Object * obj,size_t usable_size ATTRIBUTE_UNUSED) const114 void operator()(Object* obj, size_t usable_size ATTRIBUTE_UNUSED) const
115 SHARED_REQUIRES(Locks::mutator_lock_) {
116 Object::CopyObject(self_, obj, orig_->Get(), num_bytes_);
117 }
118
119 private:
120 Thread* const self_;
121 Handle<Object>* const orig_;
122 const size_t num_bytes_;
123 DISALLOW_COPY_AND_ASSIGN(CopyObjectVisitor);
124 };
125
Clone(Thread * self)126 Object* Object::Clone(Thread* self) {
127 CHECK(!IsClass()) << "Can't clone classes.";
128 // Object::SizeOf gets the right size even if we're an array. Using c->AllocObject() here would
129 // be wrong.
130 gc::Heap* heap = Runtime::Current()->GetHeap();
131 size_t num_bytes = SizeOf();
132 StackHandleScope<1> hs(self);
133 Handle<Object> this_object(hs.NewHandle(this));
134 Object* copy;
135 CopyObjectVisitor visitor(self, &this_object, num_bytes);
136 if (heap->IsMovableObject(this)) {
137 copy = heap->AllocObject<true>(self, GetClass(), num_bytes, visitor);
138 } else {
139 copy = heap->AllocNonMovableObject<true>(self, GetClass(), num_bytes, visitor);
140 }
141 return copy;
142 }
143
GenerateIdentityHashCode()144 uint32_t Object::GenerateIdentityHashCode() {
145 uint32_t expected_value, new_value;
146 do {
147 expected_value = hash_code_seed.LoadRelaxed();
148 new_value = expected_value * 1103515245 + 12345;
149 } while (!hash_code_seed.CompareExchangeWeakRelaxed(expected_value, new_value) ||
150 (expected_value & LockWord::kHashMask) == 0);
151 return expected_value & LockWord::kHashMask;
152 }
153
SetHashCodeSeed(uint32_t new_seed)154 void Object::SetHashCodeSeed(uint32_t new_seed) {
155 hash_code_seed.StoreRelaxed(new_seed);
156 }
157
IdentityHashCode() const158 int32_t Object::IdentityHashCode() const {
159 mirror::Object* current_this = const_cast<mirror::Object*>(this);
160 while (true) {
161 LockWord lw = current_this->GetLockWord(false);
162 switch (lw.GetState()) {
163 case LockWord::kUnlocked: {
164 // Try to compare and swap in a new hash, if we succeed we will return the hash on the next
165 // loop iteration.
166 LockWord hash_word = LockWord::FromHashCode(GenerateIdentityHashCode(),
167 lw.ReadBarrierState());
168 DCHECK_EQ(hash_word.GetState(), LockWord::kHashCode);
169 if (const_cast<Object*>(this)->CasLockWordWeakRelaxed(lw, hash_word)) {
170 return hash_word.GetHashCode();
171 }
172 break;
173 }
174 case LockWord::kThinLocked: {
175 // Inflate the thin lock to a monitor and stick the hash code inside of the monitor. May
176 // fail spuriously.
177 Thread* self = Thread::Current();
178 StackHandleScope<1> hs(self);
179 Handle<mirror::Object> h_this(hs.NewHandle(current_this));
180 Monitor::InflateThinLocked(self, h_this, lw, GenerateIdentityHashCode());
181 // A GC may have occurred when we switched to kBlocked.
182 current_this = h_this.Get();
183 break;
184 }
185 case LockWord::kFatLocked: {
186 // Already inflated, return the hash stored in the monitor.
187 Monitor* monitor = lw.FatLockMonitor();
188 DCHECK(monitor != nullptr);
189 return monitor->GetHashCode();
190 }
191 case LockWord::kHashCode: {
192 return lw.GetHashCode();
193 }
194 default: {
195 LOG(FATAL) << "Invalid state during hashcode " << lw.GetState();
196 break;
197 }
198 }
199 }
200 UNREACHABLE();
201 }
202
CheckFieldAssignmentImpl(MemberOffset field_offset,Object * new_value)203 void Object::CheckFieldAssignmentImpl(MemberOffset field_offset, Object* new_value) {
204 Class* c = GetClass();
205 Runtime* runtime = Runtime::Current();
206 if (runtime->GetClassLinker() == nullptr || !runtime->IsStarted() ||
207 !runtime->GetHeap()->IsObjectValidationEnabled() || !c->IsResolved()) {
208 return;
209 }
210 for (Class* cur = c; cur != nullptr; cur = cur->GetSuperClass()) {
211 for (ArtField& field : cur->GetIFields()) {
212 StackHandleScope<1> hs(Thread::Current());
213 Handle<Object> h_object(hs.NewHandle(new_value));
214 if (field.GetOffset().Int32Value() == field_offset.Int32Value()) {
215 CHECK_NE(field.GetTypeAsPrimitiveType(), Primitive::kPrimNot);
216 // TODO: resolve the field type for moving GC.
217 mirror::Class* field_type = field.GetType<!kMovingCollector>();
218 if (field_type != nullptr) {
219 CHECK(field_type->IsAssignableFrom(new_value->GetClass()));
220 }
221 return;
222 }
223 }
224 }
225 if (c->IsArrayClass()) {
226 // Bounds and assign-ability done in the array setter.
227 return;
228 }
229 if (IsClass()) {
230 for (ArtField& field : AsClass()->GetSFields()) {
231 if (field.GetOffset().Int32Value() == field_offset.Int32Value()) {
232 CHECK_NE(field.GetTypeAsPrimitiveType(), Primitive::kPrimNot);
233 // TODO: resolve the field type for moving GC.
234 mirror::Class* field_type = field.GetType<!kMovingCollector>();
235 if (field_type != nullptr) {
236 CHECK(field_type->IsAssignableFrom(new_value->GetClass()));
237 }
238 return;
239 }
240 }
241 }
242 LOG(FATAL) << "Failed to find field for assignment to " << reinterpret_cast<void*>(this)
243 << " of type " << PrettyDescriptor(c) << " at offset " << field_offset;
244 UNREACHABLE();
245 }
246
FindFieldByOffset(MemberOffset offset)247 ArtField* Object::FindFieldByOffset(MemberOffset offset) {
248 return IsClass() ? ArtField::FindStaticFieldWithOffset(AsClass(), offset.Uint32Value())
249 : ArtField::FindInstanceFieldWithOffset(GetClass(), offset.Uint32Value());
250 }
251
252 } // namespace mirror
253 } // namespace art
254