mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
76 lines
2.0 KiB
C++
76 lines
2.0 KiB
C++
/*
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This file is part of solidity.
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solidity is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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solidity is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with solidity. If not, see <http://www.gnu.org/licenses/>.
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*/
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// SPDX-License-Identifier: GPL-3.0
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/**
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* Optimisation stage that replaces expressions known to be the current value of a variable
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* in scope by a reference to that variable.
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*/
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#pragma once
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#include <libyul/optimiser/DataFlowAnalyzer.h>
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#include <libyul/optimiser/OptimiserStep.h>
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#include <libyul/optimiser/SyntacticalEquality.h>
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#include <libyul/optimiser/BlockHasher.h>
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#include <set>
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namespace solidity::yul
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{
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struct Dialect;
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struct SideEffects;
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/**
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* Optimisation stage that replaces expressions known to be the current value of a variable
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* in scope by a reference to that variable.
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*
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* Prerequisite: Disambiguator, ForLoopInitRewriter.
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*/
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class CommonSubexpressionEliminator: public DataFlowAnalyzer
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{
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public:
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static constexpr char const* name{"CommonSubexpressionEliminator"};
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static void run(OptimiserStepContext&, Block& _ast);
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using DataFlowAnalyzer::operator();
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void operator()(FunctionDefinition&) override;
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private:
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CommonSubexpressionEliminator(
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Dialect const& _dialect,
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std::map<YulString, SideEffects> _functionSideEffects
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);
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protected:
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using ASTModifier::visit;
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void visit(Expression& _e) override;
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void assignValue(YulString _variable, Expression const* _value) override;
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private:
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std::set<YulString> m_returnVariables;
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std::unordered_map<
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std::reference_wrapper<Expression const>,
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std::set<YulString>,
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ExpressionHash,
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SyntacticallyEqualExpression
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> m_replacementCandidates;
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};
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}
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