mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
128 lines
3.8 KiB
C++
128 lines
3.8 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 removes unused variables and functions.
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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/OptimiserStep.h>
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#include <libyul/YulString.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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struct Dialect;
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struct SideEffects;
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/**
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* Optimisation stage that removes unused variables and functions and also
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* removes side-effect-free expression statements.
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*
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* If msize is used, we cannot remove any statements that access memory.
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* Because of that, the Unused Pruner should only be invoked on full ASTs,
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* such that it can check for the presence of msize itself, or
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* the `_allowMSizeOptimization` needs to be passed.
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*
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* Note that this does not remove circular references.
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*
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* Prerequisite: Disambiguator
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*/
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class UnusedPruner: public ASTModifier
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{
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public:
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static constexpr char const* name{"UnusedPruner"};
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static void run(OptimiserStepContext& _context, Block& _ast);
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using ASTModifier::operator();
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void operator()(Block& _block) override;
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// @returns true iff the code changed in the previous run.
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bool shouldRunAgain() const { return m_shouldRunAgain; }
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// Run the pruner until the code does not change anymore.
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static void runUntilStabilised(
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Dialect const& _dialect,
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Block& _ast,
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bool _allowMSizeOptimization,
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std::map<YulString, SideEffects> const* _functionSideEffects = nullptr,
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std::set<YulString> const& _externallyUsedFunctions = {}
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);
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static void run(
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Dialect const& _dialect,
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Block& _ast,
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std::set<YulString> const& _externallyUsedFunctions = {}
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)
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{
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runUntilStabilisedOnFullAST(_dialect, _ast, _externallyUsedFunctions);
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}
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/// Run the pruner until the code does not change anymore.
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/// The provided block has to be a full AST.
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/// The pruner itself determines if msize is used and which user-defined functions
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/// are side-effect free.
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static void runUntilStabilisedOnFullAST(
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Dialect const& _dialect,
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Block& _ast,
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std::set<YulString> const& _externallyUsedFunctions = {}
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);
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// Run the pruner until the code does not change anymore.
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// Only run on the given function.
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// @param _allowMSizeOptimization if true, allows to remove instructions
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// whose only side-effect is a potential change of the return value of
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// the msize instruction.
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static void runUntilStabilised(
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Dialect const& _dialect,
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FunctionDefinition& _functionDefinition,
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bool _allowMSizeOptimization,
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std::set<YulString> const& _externallyUsedFunctions = {}
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);
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private:
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UnusedPruner(
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Dialect const& _dialect,
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Block& _ast,
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bool _allowMSizeOptimization,
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std::map<YulString, SideEffects> const* _functionSideEffects = nullptr,
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std::set<YulString> const& _externallyUsedFunctions = {}
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);
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UnusedPruner(
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Dialect const& _dialect,
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FunctionDefinition& _function,
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bool _allowMSizeOptimization,
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std::set<YulString> const& _externallyUsedFunctions = {}
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);
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bool used(YulString _name) const;
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void subtractReferences(std::map<YulString, size_t> const& _subtrahend);
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Dialect const& m_dialect;
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bool m_allowMSizeOptimization = false;
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std::map<YulString, SideEffects> const* m_functionSideEffects = nullptr;
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bool m_shouldRunAgain = false;
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std::map<YulString, size_t> m_references;
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};
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}
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