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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 expressions known to be the current value of a variable
* in scope by a reference to that variable.
*/
#include <libyul/optimiser/CommonSubexpressionEliminator.h>
#include <libyul/optimiser/Metrics.h>
#include <libyul/optimiser/SyntacticalEquality.h>
#include <libyul/Exceptions.h>
#include <libsolidity/inlineasm/AsmData.h>
using namespace std;
using namespace dev;
using namespace dev::yul;
void CommonSubexpressionEliminator::visit(Expression& _e)
{
// We visit the inner expression first to first simplify inner expressions,
// which hopefully allows more matches.
// Note that the DataFlowAnalyzer itself only has code for visiting Statements,
// so this basically invokes the AST walker directly and thus post-visiting
// is also fine with regards to data flow analysis.
DataFlowAnalyzer::visit(_e);
if (_e.type() == typeid(Identifier))
{
Identifier& identifier = boost::get<Identifier>(_e);
YulString name = identifier.name;
if (m_value.count(name))
{
assertThrow(m_value.at(name), OptimizerException, "");
if (m_value.at(name)->type() == typeid(Identifier))
{
YulString value = boost::get<Identifier>(*m_value.at(name)).name;
assertThrow(inScope(value), OptimizerException, "");
_e = Identifier{locationOf(_e), value};
}
}
}
else
{
// TODO this search is rather inefficient.
for (auto const& var: m_value)
{
assertThrow(var.second, OptimizerException, "");
assertThrow(inScope(var.first), OptimizerException, "");
if (SyntacticalEqualityChecker::equal(_e, *var.second))
{
_e = Identifier{locationOf(_e), var.first};
break;
}
}
}
}
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