mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
68 lines
2.2 KiB
C++
68 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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#include <libyul/optimiser/Semantics.h>
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#include <libyul/optimiser/OptimiserStep.h>
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namespace yul
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{
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/**
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* Loop-invariant code motion.
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*
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* This optimization moves movable SSA variable declarations outside the loop.
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*
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* Only statements at the top level in a loop's body or post block are considered, i.e variable
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* declarations inside conditional branches will not be moved out of the loop.
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*
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* Requirements:
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* - The Disambiguator, ForLoopInitRewriter and FunctionHoister must be run upfront.
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* - Expression splitter and SSA transform should be run upfront to obtain better result.
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*/
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class LoopInvariantCodeMotion: public ASTModifier
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{
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public:
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static constexpr char const* name{"LoopInvariantCodeMotion"};
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static void run(OptimiserStepContext& _context, Block& _ast);
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void operator()(Block& _block) override;
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private:
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explicit LoopInvariantCodeMotion(
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Dialect const& _dialect,
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std::set<YulString> const& _ssaVariables,
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std::map<YulString, SideEffects> const& _functionSideEffects
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):
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m_dialect(_dialect),
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m_ssaVariables(_ssaVariables),
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m_functionSideEffects(_functionSideEffects)
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{ }
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/// @returns true if the given variable declaration can be moved to in front of the loop.
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bool canBePromoted(VariableDeclaration const& _varDecl, std::set<YulString> const& _varsDefinedInCurrentScope) const;
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std::optional<std::vector<Statement>> rewriteLoop(ForLoop& _for);
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Dialect const& m_dialect;
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std::set<YulString> const& m_ssaVariables;
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std::map<YulString, SideEffects> const& m_functionSideEffects;
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};
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}
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