mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
95 lines
2.3 KiB
C++
95 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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/**
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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/AsmData.h>
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#include <libevmasm/SemanticInformation.h>
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#include <libevmasm/AssemblyItem.h>
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#include <algorithm>
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using namespace std;
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using namespace dev;
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using namespace yul;
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namespace
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{
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bool isTerminating(yul::ExpressionStatement const& _exprStmnt)
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{
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if (_exprStmnt.expression.type() != typeid(FunctionalInstruction))
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return false;
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auto const& funcInstr = boost::get<FunctionalInstruction>(_exprStmnt.expression);
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return eth::SemanticInformation::terminatesControlFlow(funcInstr.instruction);
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}
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/// Returns an iterator to the first terminating statement or
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/// `_block.statements.end()()` when none was found
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auto findFirstTerminatingStatement(Block& _block)
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{
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return find_if(
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_block.statements.begin(),
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_block.statements.end(),
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[](Statement const& _stmnt)
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{
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if (
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_stmnt.type() == typeid(ExpressionStatement) &&
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isTerminating(boost::get<ExpressionStatement>(_stmnt))
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)
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return true;
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else if (_stmnt.type() == typeid(Break))
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return true;
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else if (_stmnt.type() == typeid(Continue))
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return true;
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return false;
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}
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);
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}
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}
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void DeadCodeEliminator::operator()(Block& _block)
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{
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auto& statements = _block.statements;
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auto firstTerminatingStatment = findFirstTerminatingStatement(_block);
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if (
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firstTerminatingStatment != statements.end() &&
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firstTerminatingStatment + 1 != statements.end()
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)
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statements.erase(
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std::remove_if(
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firstTerminatingStatment + 1,
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statements.end(),
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[] (Statement const& _s)
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{
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return _s.type() != typeid(yul::FunctionDefinition);
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}
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),
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statements.end()
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);
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ASTModifier::operator()(_block);
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}
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