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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/>.
*/
/**
* Optimiser component that turns complex expressions into multiple variable
* declarations.
*/
#include <libyul/optimiser/ExpressionSplitter.h>
#include <libyul/optimiser/ASTWalker.h>
#include <libyul/AsmData.h>
#include <libdevcore/CommonData.h>
#include <boost/range/adaptor/reversed.hpp>
using namespace std;
using namespace dev;
using namespace langutil;
using namespace dev::yul;
using namespace dev::solidity;
void ExpressionSplitter::operator()(FunctionalInstruction& _instruction)
{
for (auto& arg: _instruction.arguments | boost::adaptors::reversed)
outlineExpression(arg);
}
void ExpressionSplitter::operator()(FunctionCall& _funCall)
{
for (auto& arg: _funCall.arguments | boost::adaptors::reversed)
outlineExpression(arg);
}
void ExpressionSplitter::operator()(If& _if)
{
outlineExpression(*_if.condition);
(*this)(_if.body);
}
void ExpressionSplitter::operator()(Switch& _switch)
{
outlineExpression(*_switch.expression);
for (auto& _case: _switch.cases)
// Do not visit the case expression, nothing to split there.
(*this)(_case.body);
}
void ExpressionSplitter::operator()(ForLoop& _loop)
{
(*this)(_loop.pre);
// Do not visit the condition because we cannot split expressions there.
(*this)(_loop.post);
(*this)(_loop.body);
}
void ExpressionSplitter::operator()(Block& _block)
{
vector<Statement> saved;
swap(saved, m_statementsToPrefix);
function<boost::optional<vector<Statement>>(Statement&)> f =
[&](Statement& _statement) -> boost::optional<vector<Statement>> {
m_statementsToPrefix.clear();
visit(_statement);
if (m_statementsToPrefix.empty())
return {};
m_statementsToPrefix.emplace_back(std::move(_statement));
return std::move(m_statementsToPrefix);
};
iterateReplacing(_block.statements, f);
swap(saved, m_statementsToPrefix);
}
void ExpressionSplitter::outlineExpression(Expression& _expr)
{
if (_expr.type() == typeid(Identifier))
return;
visit(_expr);
SourceLocation location = locationOf(_expr);
YulString var = m_nameDispenser.newName({});
m_statementsToPrefix.emplace_back(VariableDeclaration{
location,
{{TypedName{location, var, {}}}},
make_shared<Expression>(std::move(_expr))
});
_expr = Identifier{location, var};
}
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