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 "array-inl.h"
22 #include "art_field-inl.h"
23 #include "art_field.h"
24 #include "class-inl.h"
25 #include "class.h"
26 #include "class_linker-inl.h"
27 #include "dex/descriptors_names.h"
28 #include "dex/dex_file-inl.h"
29 #include "gc/accounting/card_table-inl.h"
30 #include "gc/heap.h"
31 #include "handle_scope-inl.h"
32 #include "iftable-inl.h"
33 #include "monitor.h"
34 #include "object-inl.h"
35 #include "object-refvisitor-inl.h"
36 #include "object_array-inl.h"
37 #include "runtime.h"
38 #include "throwable.h"
39 #include "well_known_classes.h"
40
41 namespace art {
42 namespace mirror {
43
44 Atomic<uint32_t> Object::hash_code_seed(987654321U + std::time(nullptr));
45
46 class CopyReferenceFieldsWithReadBarrierVisitor {
47 public:
CopyReferenceFieldsWithReadBarrierVisitor(ObjPtr<Object> dest_obj)48 explicit CopyReferenceFieldsWithReadBarrierVisitor(ObjPtr<Object> dest_obj)
49 : dest_obj_(dest_obj) {}
50
operator ()(ObjPtr<Object> obj,MemberOffset offset,bool) const51 void operator()(ObjPtr<Object> obj, MemberOffset offset, bool /* is_static */) const
52 ALWAYS_INLINE REQUIRES_SHARED(Locks::mutator_lock_) {
53 // GetFieldObject() contains a RB.
54 ObjPtr<Object> ref = obj->GetFieldObject<Object>(offset);
55 // No WB here as a large object space does not have a card table
56 // coverage. Instead, cards will be marked separately.
57 dest_obj_->SetFieldObjectWithoutWriteBarrier<false, false>(offset, ref);
58 }
59
operator ()(ObjPtr<mirror::Class> klass,mirror::Reference * ref) const60 void operator()(ObjPtr<mirror::Class> klass, mirror::Reference* ref) const
61 ALWAYS_INLINE REQUIRES_SHARED(Locks::mutator_lock_) {
62 // Copy java.lang.ref.Reference.referent which isn't visited in
63 // Object::VisitReferences().
64 DCHECK(klass->IsTypeOfReferenceClass());
65 this->operator()(ref, mirror::Reference::ReferentOffset(), false);
66 }
67
68 // Unused since we don't copy class native roots.
VisitRootIfNonNull(mirror::CompressedReference<mirror::Object> * root ATTRIBUTE_UNUSED) const69 void VisitRootIfNonNull(mirror::CompressedReference<mirror::Object>* root ATTRIBUTE_UNUSED)
70 const {}
VisitRoot(mirror::CompressedReference<mirror::Object> * root ATTRIBUTE_UNUSED) const71 void VisitRoot(mirror::CompressedReference<mirror::Object>* root ATTRIBUTE_UNUSED) const {}
72
73 private:
74 ObjPtr<Object> const dest_obj_;
75 };
76
CopyObject(ObjPtr<mirror::Object> dest,ObjPtr<mirror::Object> src,size_t num_bytes)77 Object* Object::CopyObject(ObjPtr<mirror::Object> dest,
78 ObjPtr<mirror::Object> src,
79 size_t num_bytes) {
80 // Copy instance data. Don't assume memcpy copies by words (b/32012820).
81 {
82 const size_t offset = sizeof(Object);
83 uint8_t* src_bytes = reinterpret_cast<uint8_t*>(src.Ptr()) + offset;
84 uint8_t* dst_bytes = reinterpret_cast<uint8_t*>(dest.Ptr()) + offset;
85 num_bytes -= offset;
86 DCHECK_ALIGNED(src_bytes, sizeof(uintptr_t));
87 DCHECK_ALIGNED(dst_bytes, sizeof(uintptr_t));
88 // Use word sized copies to begin.
89 while (num_bytes >= sizeof(uintptr_t)) {
90 reinterpret_cast<Atomic<uintptr_t>*>(dst_bytes)->StoreRelaxed(
91 reinterpret_cast<Atomic<uintptr_t>*>(src_bytes)->LoadRelaxed());
92 src_bytes += sizeof(uintptr_t);
93 dst_bytes += sizeof(uintptr_t);
94 num_bytes -= sizeof(uintptr_t);
95 }
96 // Copy possible 32 bit word.
97 if (sizeof(uintptr_t) != sizeof(uint32_t) && num_bytes >= sizeof(uint32_t)) {
98 reinterpret_cast<Atomic<uint32_t>*>(dst_bytes)->StoreRelaxed(
99 reinterpret_cast<Atomic<uint32_t>*>(src_bytes)->LoadRelaxed());
100 src_bytes += sizeof(uint32_t);
101 dst_bytes += sizeof(uint32_t);
102 num_bytes -= sizeof(uint32_t);
103 }
104 // Copy remaining bytes, avoid going past the end of num_bytes since there may be a redzone
105 // there.
106 while (num_bytes > 0) {
107 reinterpret_cast<Atomic<uint8_t>*>(dst_bytes)->StoreRelaxed(
108 reinterpret_cast<Atomic<uint8_t>*>(src_bytes)->LoadRelaxed());
109 src_bytes += sizeof(uint8_t);
110 dst_bytes += sizeof(uint8_t);
111 num_bytes -= sizeof(uint8_t);
112 }
113 }
114
115 if (kUseReadBarrier) {
116 // We need a RB here. After copying the whole object above, copy references fields one by one
117 // again with a RB to make sure there are no from space refs. TODO: Optimize this later?
118 CopyReferenceFieldsWithReadBarrierVisitor visitor(dest);
119 src->VisitReferences(visitor, visitor);
120 }
121 gc::Heap* heap = Runtime::Current()->GetHeap();
122 // Perform write barriers on copied object references.
123 ObjPtr<Class> c = src->GetClass();
124 if (c->IsArrayClass()) {
125 if (!c->GetComponentType()->IsPrimitive()) {
126 ObjectArray<Object>* array = dest->AsObjectArray<Object>();
127 heap->WriteBarrierArray(dest, 0, array->GetLength());
128 }
129 } else {
130 heap->WriteBarrierEveryFieldOf(dest);
131 }
132 return dest.Ptr();
133 }
134
135 // An allocation pre-fence visitor that copies the object.
136 class CopyObjectVisitor {
137 public:
CopyObjectVisitor(Handle<Object> * orig,size_t num_bytes)138 CopyObjectVisitor(Handle<Object>* orig, size_t num_bytes)
139 : orig_(orig), num_bytes_(num_bytes) {}
140
operator ()(ObjPtr<Object> obj,size_t usable_size ATTRIBUTE_UNUSED) const141 void operator()(ObjPtr<Object> obj, size_t usable_size ATTRIBUTE_UNUSED) const
142 REQUIRES_SHARED(Locks::mutator_lock_) {
143 Object::CopyObject(obj, orig_->Get(), num_bytes_);
144 }
145
146 private:
147 Handle<Object>* const orig_;
148 const size_t num_bytes_;
149 DISALLOW_COPY_AND_ASSIGN(CopyObjectVisitor);
150 };
151
Clone(Thread * self)152 Object* Object::Clone(Thread* self) {
153 CHECK(!IsClass()) << "Can't clone classes.";
154 // Object::SizeOf gets the right size even if we're an array. Using c->AllocObject() here would
155 // be wrong.
156 gc::Heap* heap = Runtime::Current()->GetHeap();
157 size_t num_bytes = SizeOf();
158 StackHandleScope<1> hs(self);
159 Handle<Object> this_object(hs.NewHandle(this));
160 ObjPtr<Object> copy;
161 CopyObjectVisitor visitor(&this_object, num_bytes);
162 if (heap->IsMovableObject(this)) {
163 copy = heap->AllocObject<true>(self, GetClass(), num_bytes, visitor);
164 } else {
165 copy = heap->AllocNonMovableObject<true>(self, GetClass(), num_bytes, visitor);
166 }
167 if (this_object->GetClass()->IsFinalizable()) {
168 heap->AddFinalizerReference(self, ©);
169 }
170 return copy.Ptr();
171 }
172
GenerateIdentityHashCode()173 uint32_t Object::GenerateIdentityHashCode() {
174 uint32_t expected_value, new_value;
175 do {
176 expected_value = hash_code_seed.LoadRelaxed();
177 new_value = expected_value * 1103515245 + 12345;
178 } while (!hash_code_seed.CompareAndSetWeakRelaxed(expected_value, new_value) ||
179 (expected_value & LockWord::kHashMask) == 0);
180 return expected_value & LockWord::kHashMask;
181 }
182
SetHashCodeSeed(uint32_t new_seed)183 void Object::SetHashCodeSeed(uint32_t new_seed) {
184 hash_code_seed.StoreRelaxed(new_seed);
185 }
186
IdentityHashCode()187 int32_t Object::IdentityHashCode() {
188 ObjPtr<Object> current_this = this; // The this pointer may get invalidated by thread suspension.
189 while (true) {
190 LockWord lw = current_this->GetLockWord(false);
191 switch (lw.GetState()) {
192 case LockWord::kUnlocked: {
193 // Try to compare and swap in a new hash, if we succeed we will return the hash on the next
194 // loop iteration.
195 LockWord hash_word = LockWord::FromHashCode(GenerateIdentityHashCode(), lw.GCState());
196 DCHECK_EQ(hash_word.GetState(), LockWord::kHashCode);
197 if (current_this->CasLockWordWeakRelaxed(lw, hash_word)) {
198 return hash_word.GetHashCode();
199 }
200 break;
201 }
202 case LockWord::kThinLocked: {
203 // Inflate the thin lock to a monitor and stick the hash code inside of the monitor. May
204 // fail spuriously.
205 Thread* self = Thread::Current();
206 StackHandleScope<1> hs(self);
207 Handle<mirror::Object> h_this(hs.NewHandle(current_this));
208 Monitor::InflateThinLocked(self, h_this, lw, GenerateIdentityHashCode());
209 // A GC may have occurred when we switched to kBlocked.
210 current_this = h_this.Get();
211 break;
212 }
213 case LockWord::kFatLocked: {
214 // Already inflated, return the hash stored in the monitor.
215 Monitor* monitor = lw.FatLockMonitor();
216 DCHECK(monitor != nullptr);
217 return monitor->GetHashCode();
218 }
219 case LockWord::kHashCode: {
220 return lw.GetHashCode();
221 }
222 default: {
223 LOG(FATAL) << "Invalid state during hashcode " << lw.GetState();
224 break;
225 }
226 }
227 }
228 UNREACHABLE();
229 }
230
CheckFieldAssignmentImpl(MemberOffset field_offset,ObjPtr<Object> new_value)231 void Object::CheckFieldAssignmentImpl(MemberOffset field_offset, ObjPtr<Object> new_value) {
232 ObjPtr<Class> c = GetClass();
233 Runtime* runtime = Runtime::Current();
234 if (runtime->GetClassLinker() == nullptr || !runtime->IsStarted() ||
235 !runtime->GetHeap()->IsObjectValidationEnabled() || !c->IsResolved()) {
236 return;
237 }
238 for (ObjPtr<Class> cur = c; cur != nullptr; cur = cur->GetSuperClass()) {
239 for (ArtField& field : cur->GetIFields()) {
240 if (field.GetOffset().Int32Value() == field_offset.Int32Value()) {
241 CHECK_NE(field.GetTypeAsPrimitiveType(), Primitive::kPrimNot);
242 // TODO: resolve the field type for moving GC.
243 ObjPtr<mirror::Class> field_type =
244 kMovingCollector ? field.LookupResolvedType() : field.ResolveType();
245 if (field_type != nullptr) {
246 CHECK(field_type->IsAssignableFrom(new_value->GetClass()));
247 }
248 return;
249 }
250 }
251 }
252 if (c->IsArrayClass()) {
253 // Bounds and assign-ability done in the array setter.
254 return;
255 }
256 if (IsClass()) {
257 for (ArtField& field : AsClass()->GetSFields()) {
258 if (field.GetOffset().Int32Value() == field_offset.Int32Value()) {
259 CHECK_NE(field.GetTypeAsPrimitiveType(), Primitive::kPrimNot);
260 // TODO: resolve the field type for moving GC.
261 ObjPtr<mirror::Class> field_type =
262 kMovingCollector ? field.LookupResolvedType() : field.ResolveType();
263 if (field_type != nullptr) {
264 CHECK(field_type->IsAssignableFrom(new_value->GetClass()));
265 }
266 return;
267 }
268 }
269 }
270 LOG(FATAL) << "Failed to find field for assignment to " << reinterpret_cast<void*>(this)
271 << " of type " << c->PrettyDescriptor() << " at offset " << field_offset;
272 UNREACHABLE();
273 }
274
FindFieldByOffset(MemberOffset offset)275 ArtField* Object::FindFieldByOffset(MemberOffset offset) {
276 return IsClass() ? ArtField::FindStaticFieldWithOffset(AsClass(), offset.Uint32Value())
277 : ArtField::FindInstanceFieldWithOffset(GetClass(), offset.Uint32Value());
278 }
279
PrettyTypeOf(ObjPtr<mirror::Object> obj)280 std::string Object::PrettyTypeOf(ObjPtr<mirror::Object> obj) {
281 if (obj == nullptr) {
282 return "null";
283 }
284 return obj->PrettyTypeOf();
285 }
286
PrettyTypeOf()287 std::string Object::PrettyTypeOf() {
288 // From-space version is the same as the to-space version since the dex file never changes.
289 // Avoiding the read barrier here is important to prevent recursive AssertToSpaceInvariant
290 // issues.
291 ObjPtr<mirror::Class> klass = GetClass<kDefaultVerifyFlags, kWithoutReadBarrier>();
292 if (klass == nullptr) {
293 return "(raw)";
294 }
295 std::string temp;
296 std::string result(PrettyDescriptor(klass->GetDescriptor(&temp)));
297 if (klass->IsClassClass()) {
298 result += "<" + PrettyDescriptor(AsClass()->GetDescriptor(&temp)) + ">";
299 }
300 return result;
301 }
302
303 } // namespace mirror
304 } // namespace art
305