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66 lines
2.4 KiB
66 lines
2.4 KiB
4 months ago
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/*
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* Copyright (C) 2017 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ART_COMPILER_OPTIMIZING_CONSTRUCTOR_FENCE_REDUNDANCY_ELIMINATION_H_
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#define ART_COMPILER_OPTIMIZING_CONSTRUCTOR_FENCE_REDUNDANCY_ELIMINATION_H_
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#include "optimization.h"
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namespace art {
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/*
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* Constructor Fence Redundancy Elimination (CFRE).
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*
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* A local optimization pass that merges redundant constructor fences
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* together within the same basic block.
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*
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* Abbreviations:
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* - CF: Constructor Fence
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* - CFS: Constructor Fence Set
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* - CFTargets: The unique set of the inputs of all the instructions in CFS.
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*
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* Given any CFS = { CF(x), CF(y), CF(z), ... }, define CFTargets = { x, y, z, ... }.
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* - Publish(R) must not exist for any R in CFTargets if this Publish(R) is between any CF in CFS.
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* - This type of Publish(R) is called an "interesting publish".
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*
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* A Publish(R) is considered any instruction at which the reference to "R"
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* may escape (e.g. invoke, store, return, etc) to another thread.
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*
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* Starting at the beginning of the block:
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* - Find the largest contiguous CFS.
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* - If we see an interesting publish, merge all instructions in CFS into a single CF(CFTargets).
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* - Repeat until the block is fully visited.
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* - At the end of the block, merge all instructions in CFS into a single CF(CFTargets).
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*/
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class ConstructorFenceRedundancyElimination : public HOptimization {
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public:
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ConstructorFenceRedundancyElimination(HGraph* graph,
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OptimizingCompilerStats* stats,
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const char* name = kCFREPassName)
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: HOptimization(graph, name, stats) {}
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bool Run() override;
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static constexpr const char* kCFREPassName = "constructor_fence_redundancy_elimination";
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private:
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DISALLOW_COPY_AND_ASSIGN(ConstructorFenceRedundancyElimination);
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};
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} // namespace art
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#endif // ART_COMPILER_OPTIMIZING_CONSTRUCTOR_FENCE_REDUNDANCY_ELIMINATION_H_
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