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75 lines
2.3 KiB
75 lines
2.3 KiB
/*
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This file is part of cpp-ethereum.
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cpp-ethereum 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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cpp-ethereum 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 cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @file ExpressionClasses.h
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* @author Christian <c@ethdev.com>
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* @date 2015
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* Container for equivalence classes of expressions for use in common subexpression elimination.
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*/
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#pragma once
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#include <vector>
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#include <map>
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#include <memory>
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namespace dev
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{
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namespace eth
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{
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class AssemblyItem;
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/**
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* Collection of classes of equivalent expressions that can also determine the class of an expression.
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* Identifiers are contiguously assigned to new classes starting from zero.
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*/
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class ExpressionClasses
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{
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public:
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using Id = unsigned;
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using Ids = std::vector<Id>;
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struct Expression
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{
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Id id;
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AssemblyItem const* item;
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Ids arguments;
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bool operator<(Expression const& _other) const;
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};
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/// Retrieves the id of the expression equivalence class resulting from the given item applied to the
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/// given classes, might also create a new one.
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Id find(AssemblyItem const& _item, Ids const& _arguments = {});
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/// @returns the canonical representative of an expression class.
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Expression const& representative(Id _id) const { return m_representatives.at(_id); }
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/// @returns the number of classes.
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Id size() const { return m_representatives.size(); }
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private:
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/// Tries to simplify the given expression.
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/// @returns its class if it possible or Id(-1) otherwise.
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/// @param _secondRun is set to true for the second run where arguments of commutative expressions are reversed
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Id tryToSimplify(Expression const& _expr, bool _secondRun = false);
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/// Expression equivalence class representatives - we only store one item of an equivalence.
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std::vector<Expression> m_representatives;
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std::vector<std::shared_ptr<AssemblyItem>> m_spareAssemblyItem;
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};
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}
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}
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