mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
65 lines
2.0 KiB
C++
65 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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* Component that collects variables that are never assigned to and their
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* initial values.
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*/
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#pragma once
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#include <libyul/optimiser/ASTWalker.h>
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#include <libyul/AsmData.h>
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#include <map>
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#include <set>
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namespace solidity::yul
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{
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/**
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* Class that walks the AST and stores the initial value of each variable
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* that is never assigned to.
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*
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* A special zero constant expression is used for the default value of variables.
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*
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* Prerequisite: Disambiguator
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*/
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class SSAValueTracker: public ASTWalker
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{
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public:
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using ASTWalker::operator();
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void operator()(FunctionDefinition const& _funDef) override;
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void operator()(VariableDeclaration const& _varDecl) override;
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void operator()(Assignment const& _assignment) override;
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std::map<YulString, Expression const*> const& values() const { return m_values; }
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Expression const* value(YulString _name) const { return m_values.at(_name); }
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static std::set<YulString> ssaVariables(Block const& _ast);
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private:
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void setValue(YulString _name, Expression const* _value);
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/// Special expression whose address will be used in m_values.
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/// YulString does not need to be reset because SSAValueTracker is short-lived.
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Expression const m_zero{Literal{{}, LiteralKind::Number, YulString{"0"}, {}}};
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std::map<YulString, Expression const*> m_values;
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};
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}
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