mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
73 lines
2.2 KiB
C++
73 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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// 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/YulString.h>
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#include <libyul/ControlFlowSideEffects.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 OptimiserStepContext;
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/**
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* Optimisation stage that removes unreachable code
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*
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* Unreachable code is any code within a block which is preceded by a
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* leave, return, invalid, break, continue, selfdestruct or revert or
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* a call to a user-defined function that never returns (either due to
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* recursion or a call to return / revert / stop).
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*
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* Function definitions are retained as they might be called by earlier
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* code and thus are considered reachable.
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*
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* Because variables declared in a for loop's init block have their scope extended to the loop body,
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* we require ForLoopInitRewriter to run before this step.
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*
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* Prerequisite: ForLoopInitRewriter, Function Hoister, Function Grouper
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*/
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class DeadCodeEliminator: public ASTModifier
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{
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public:
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static constexpr char const* name{"DeadCodeEliminator"};
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static void run(OptimiserStepContext&, Block& _ast);
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using ASTModifier::operator();
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void operator()(ForLoop& _for) override;
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void operator()(Block& _block) override;
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private:
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DeadCodeEliminator(
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Dialect const& _dialect,
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std::map<YulString, ControlFlowSideEffects> _sideEffects
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): m_dialect(_dialect), m_functionSideEffects(std::move(_sideEffects)) {}
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Dialect const& m_dialect;
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std::map<YulString, ControlFlowSideEffects> m_functionSideEffects;
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};
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}
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