mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
67 lines
2.2 KiB
C++
67 lines
2.2 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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#pragma once
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#include <libyul/optimiser/ASTWalker.h>
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namespace yul
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{
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struct Dialect;
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/**
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* Simplifies several control-flow structures:
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* - replace if with empty body with pop(condition)
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* - remove empty default switch case
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* - remove empty switch case if no default case exists
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* - replace switch with no cases with pop(expression)
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* - turn switch with single case into if
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* - replace switch with only default case with pop(expression) and body
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* - replace switch with const expr with matching case body
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* - replace ``for`` with terminating control flow and without other break/continue by ``if``
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*
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* None of these operations depend on the data flow. The StructuralSimplifier
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* performs similar tasks that do depend on data flow.
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*
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* The ControlFlowSimplifier does record the presence or absence of ``break``
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* and ``continue`` statements during its traversal.
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*
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* Prerequisite: Disambiguator, FunctionHoister, ForLoopInitRewriter.
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*
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* Important: Introduces EVM opcodes and thus can only be used on EVM code for now.
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*/
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class ControlFlowSimplifier: public ASTModifier
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{
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public:
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ControlFlowSimplifier(Dialect const& _dialect): m_dialect(_dialect) {}
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using ASTModifier::operator();
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void operator()(Break&) override { ++m_numBreakStatements; }
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void operator()(Continue&) override { ++m_numContinueStatements; }
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void operator()(Block& _block) override;
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void visit(Statement& _st) override;
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private:
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void simplify(std::vector<Statement>& _statements);
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Dialect const& m_dialect;
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size_t m_numBreakStatements = 0;
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size_t m_numContinueStatements = 0;
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};
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}
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