mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
71 lines
2.3 KiB
C++
71 lines
2.3 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 unreachable code.
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*/
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#include <libyul/optimiser/DeadCodeEliminator.h>
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#include <libyul/optimiser/Semantics.h>
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#include <libyul/optimiser/OptimiserStep.h>
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#include <libyul/ControlFlowSideEffectsCollector.h>
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#include <libyul/AST.h>
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#include <libevmasm/SemanticInformation.h>
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#include <algorithm>
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#include <limits>
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using namespace solidity;
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using namespace solidity::util;
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using namespace solidity::yul;
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void DeadCodeEliminator::run(OptimiserStepContext& _context, Block& _ast)
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{
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ControlFlowSideEffectsCollector sideEffects(_context.dialect, _ast);
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DeadCodeEliminator{
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_context.dialect,
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sideEffects.functionSideEffectsNamed()
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}(_ast);
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}
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void DeadCodeEliminator::operator()(ForLoop& _for)
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{
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yulAssert(_for.pre.statements.empty(), "DeadCodeEliminator needs ForLoopInitRewriter as a prerequisite.");
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ASTModifier::operator()(_for);
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}
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void DeadCodeEliminator::operator()(Block& _block)
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{
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TerminationFinder::ControlFlow controlFlowChange;
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size_t index;
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std::tie(controlFlowChange, index) = TerminationFinder{m_dialect, &m_functionSideEffects}.firstUnconditionalControlFlowChange(_block.statements);
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// Erase everything after the terminating statement that is not a function definition.
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if (controlFlowChange != TerminationFinder::ControlFlow::FlowOut && index != std::numeric_limits<size_t>::max())
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_block.statements.erase(
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remove_if(
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_block.statements.begin() + static_cast<ptrdiff_t>(index) + 1,
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_block.statements.end(),
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[] (Statement const& _s) { return !std::holds_alternative<yul::FunctionDefinition>(_s); }
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),
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_block.statements.end()
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);
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ASTModifier::operator()(_block);
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}
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