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
|
/*
* Copyright (C) 2022 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.
*/
#ifndef ART_COMPILER_OPTIMIZING_WRITE_BARRIER_ELIMINATION_H_
#define ART_COMPILER_OPTIMIZING_WRITE_BARRIER_ELIMINATION_H_
#include "base/macros.h"
#include "optimization.h"
namespace art HIDDEN {
// Eliminates unnecessary write barriers from InstanceFieldSet, StaticFieldSet, and ArraySet.
//
// We can eliminate redundant write barriers as we don't need several for the same receiver. For
// example:
// MyObject o;
// o.inner_obj = io;
// o.inner_obj2 = io2;
// o.inner_obj3 = io3;
// We can keep the write barrier for `inner_obj` and remove the other two.
//
// In order to do this, we set the WriteBarrierKind of the instruction. The instruction's kind are
// set to kEmitNoNullCheck (if this write barrier coalesced other write barriers, we don't want to
// perform the null check optimization), or to kDontEmit (if the write barrier as a whole is not
// needed).
class WriteBarrierElimination : public HOptimization {
public:
WriteBarrierElimination(HGraph* graph,
OptimizingCompilerStats* stats,
const char* name = kWBEPassName)
: HOptimization(graph, name, stats) {}
bool Run() override;
static constexpr const char* kWBEPassName = "write_barrier_elimination";
private:
DISALLOW_COPY_AND_ASSIGN(WriteBarrierElimination);
};
} // namespace art
#endif // ART_COMPILER_OPTIMIZING_WRITE_BARRIER_ELIMINATION_H_
|
