libyul/optimiser/Rematerialiser.cpp


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/*(
    This file is part of solidity.

    solidity is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    solidity is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * Optimisation stage that replaces variables by their most recently assigned expressions.
 */

#include <libyul/optimiser/Rematerialiser.h>

#include <libyul/optimiser/Metrics.h>
#include <libyul/optimiser/ASTCopier.h>
#include <libyul/Exceptions.h>

#include <libsolidity/inlineasm/AsmData.h>

using namespace std;
using namespace dev;
using namespace dev::yul;

void Rematerialiser::visit(Expression& _e)
{
    if (_e.type() == typeid(Identifier))
    {
        Identifier& identifier = boost::get<Identifier>(_e);
        if (m_value.count(identifier.name))
        {
            string name = identifier.name;
            bool expressionValid = true;
            for (auto const& ref: m_references[name])
                if (!inScope(ref))
                {
                    expressionValid = false;
                    break;
                }
            assertThrow(m_value.at(name), OptimizerException, "");
            auto const& value = *m_value.at(name);
            if (expressionValid && CodeSize::codeSize(value) <= 7)
                _e = (ASTCopier{}).translate(value);
        }
    }
    DataFlowAnalyzer::visit(_e);
}