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Diffstat (limited to 'compiler/optimizing/write_barrier_elimination.h')
-rw-r--r-- | compiler/optimizing/write_barrier_elimination.h | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/compiler/optimizing/write_barrier_elimination.h b/compiler/optimizing/write_barrier_elimination.h new file mode 100644 index 0000000000..a3769e7421 --- /dev/null +++ b/compiler/optimizing/write_barrier_elimination.h @@ -0,0 +1,56 @@ +/* + * 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_ |