1 /*
2  * Copyright (C) 2018 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_WRITE_BARRIER_H_
18 #define ART_RUNTIME_WRITE_BARRIER_H_
19 
20 #include "base/macros.h"
21 
22 namespace art {
23 
24 namespace gc {
25 namespace accounting {
26 class CardTable;
27 }  // namespace accounting
28 }  // namespace gc
29 
30 class WriteBarrier {
31  public:
32   enum NullCheck {
33     kWithoutNullCheck,
34     kWithNullCheck,
35   };
36 
37   // Must be called if a reference field of an Object in the heap changes, and before any GC
38   // safe-point. The call is not needed if null is stored in the field.
39   template <NullCheck kNullCheck = kWithNullCheck>
40   ALWAYS_INLINE static void ForFieldWrite(ObjPtr<mirror::Object> dst,
41                                           MemberOffset offset ATTRIBUTE_UNUSED,
42                                           ObjPtr<mirror::Object> new_value ATTRIBUTE_UNUSED)
43       REQUIRES_SHARED(Locks::mutator_lock_);
44 
45   // Must be called if a reference field of an ObjectArray in the heap changes, and before any GC
46   // safe-point. The call is not needed if null is stored in the field.
47   ALWAYS_INLINE static void ForArrayWrite(ObjPtr<mirror::Object> dst,
48                                           int start_offset ATTRIBUTE_UNUSED,
49                                           size_t length ATTRIBUTE_UNUSED)
50       REQUIRES_SHARED(Locks::mutator_lock_);
51 
52   // Write barrier for every reference field in an object.
53   ALWAYS_INLINE static void ForEveryFieldWrite(ObjPtr<mirror::Object> obj)
54       REQUIRES_SHARED(Locks::mutator_lock_);
55 
56  private:
57   ALWAYS_INLINE static gc::accounting::CardTable* GetCardTable();
58 };
59 
60 }  // namespace art
61 
62 #endif  // ART_RUNTIME_WRITE_BARRIER_H_
63