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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/optimiser/NameCollector.h>
#include <libyul/Exceptions.h>
#include <libyul/AsmData.h>
using namespace std;
using namespace dev;
using namespace yul;
void Rematerialiser::run(Dialect const& _dialect, Block& _ast)
{
Rematerialiser{_dialect, _ast}(_ast);
}
Rematerialiser::Rematerialiser(Dialect const& _dialect, Block& _ast):
DataFlowAnalyzer(_dialect),
m_referenceCounts(ReferencesCounter::countReferences(_ast))
{
}
void Rematerialiser::visit(Expression& _e)
{
if (_e.type() == typeid(Identifier))
{
Identifier& identifier = boost::get<Identifier>(_e);
if (m_value.count(identifier.name))
{
YulString name = identifier.name;
assertThrow(m_value.at(name), OptimizerException, "");
auto const& value = *m_value.at(name);
size_t refs = m_referenceCounts[name];
size_t cost = CodeCost::codeCost(value);
if (refs <= 1 || cost == 0 || (refs <= 5 && cost <= 1))
{
assertThrow(m_referenceCounts[name] > 0, OptimizerException, "");
for (auto const& ref: m_references[name])
assertThrow(inScope(ref), OptimizerException, "");
// update reference counts
m_referenceCounts[name]--;
for (auto const& ref: ReferencesCounter::countReferences(value))
m_referenceCounts[ref.first] += ref.second;
_e = (ASTCopier{}).translate(value);
}
}
}
DataFlowAnalyzer::visit(_e);
}
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