1 /*
2 * Copyright (C) 2015 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 #ifndef ART_RUNTIME_GC_COLLECTOR_CONCURRENT_COPYING_INL_H_
18 #define ART_RUNTIME_GC_COLLECTOR_CONCURRENT_COPYING_INL_H_
19
20 #include "concurrent_copying.h"
21
22 #include "gc/accounting/space_bitmap-inl.h"
23 #include "gc/heap.h"
24 #include "gc/space/region_space.h"
25 #include "lock_word.h"
26
27 namespace art {
28 namespace gc {
29 namespace collector {
30
Mark(mirror::Object * from_ref)31 inline mirror::Object* ConcurrentCopying::Mark(mirror::Object* from_ref) {
32 if (from_ref == nullptr) {
33 return nullptr;
34 }
35 DCHECK(heap_->collector_type_ == kCollectorTypeCC);
36 if (UNLIKELY(kUseBakerReadBarrier && !is_active_)) {
37 // In the lock word forward address state, the read barrier bits
38 // in the lock word are part of the stored forwarding address and
39 // invalid. This is usually OK as the from-space copy of objects
40 // aren't accessed by mutators due to the to-space
41 // invariant. However, during the dex2oat image writing relocation
42 // and the zygote compaction, objects can be in the forward
43 // address state (to store the forward/relocation addresses) and
44 // they can still be accessed and the invalid read barrier bits
45 // are consulted. If they look like gray but aren't really, the
46 // read barriers slow path can trigger when it shouldn't. To guard
47 // against this, return here if the CC collector isn't running.
48 return from_ref;
49 }
50 DCHECK(region_space_ != nullptr) << "Read barrier slow path taken when CC isn't running?";
51 space::RegionSpace::RegionType rtype = region_space_->GetRegionType(from_ref);
52 switch (rtype) {
53 case space::RegionSpace::RegionType::kRegionTypeToSpace:
54 // It's already marked.
55 return from_ref;
56 case space::RegionSpace::RegionType::kRegionTypeFromSpace: {
57 mirror::Object* to_ref = GetFwdPtr(from_ref);
58 if (kUseBakerReadBarrier) {
59 DCHECK_NE(to_ref, ReadBarrier::GrayPtr())
60 << "from_ref=" << from_ref << " to_ref=" << to_ref;
61 }
62 if (to_ref == nullptr) {
63 // It isn't marked yet. Mark it by copying it to the to-space.
64 to_ref = Copy(from_ref);
65 }
66 DCHECK(region_space_->IsInToSpace(to_ref) || heap_->non_moving_space_->HasAddress(to_ref))
67 << "from_ref=" << from_ref << " to_ref=" << to_ref;
68 return to_ref;
69 }
70 case space::RegionSpace::RegionType::kRegionTypeUnevacFromSpace: {
71 // This may or may not succeed, which is ok.
72 if (kUseBakerReadBarrier) {
73 from_ref->AtomicSetReadBarrierPointer(ReadBarrier::WhitePtr(), ReadBarrier::GrayPtr());
74 }
75 mirror::Object* to_ref = from_ref;
76 if (region_space_bitmap_->AtomicTestAndSet(from_ref)) {
77 // Already marked.
78 } else {
79 // Newly marked.
80 if (kUseBakerReadBarrier) {
81 DCHECK_EQ(to_ref->GetReadBarrierPointer(), ReadBarrier::GrayPtr());
82 }
83 PushOntoMarkStack(to_ref);
84 }
85 return to_ref;
86 }
87 case space::RegionSpace::RegionType::kRegionTypeNone:
88 return MarkNonMoving(from_ref);
89 default:
90 UNREACHABLE();
91 }
92 }
93
GetFwdPtr(mirror::Object * from_ref)94 inline mirror::Object* ConcurrentCopying::GetFwdPtr(mirror::Object* from_ref) {
95 DCHECK(region_space_->IsInFromSpace(from_ref));
96 LockWord lw = from_ref->GetLockWord(false);
97 if (lw.GetState() == LockWord::kForwardingAddress) {
98 mirror::Object* fwd_ptr = reinterpret_cast<mirror::Object*>(lw.ForwardingAddress());
99 DCHECK(fwd_ptr != nullptr);
100 return fwd_ptr;
101 } else {
102 return nullptr;
103 }
104 }
105
106 } // namespace collector
107 } // namespace gc
108 } // namespace art
109
110 #endif // ART_RUNTIME_GC_COLLECTOR_CONCURRENT_COPYING_INL_H_
111