solidity/libyul/optimiser/SSAValueTracker.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/>.
*/
/**
* Component that collects variables that are never assigned to and their
* initial values.
*/
#include <libyul/optimiser/SSAValueTracker.h>
#include <libyul/AsmData.h>
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using namespace std;
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using namespace solidity;
using namespace solidity::yul;
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void SSAValueTracker::operator()(Assignment const& _assignment)
{
for (auto const& var: _assignment.variableNames)
m_values.erase(var.name);
}
void SSAValueTracker::operator()(FunctionDefinition const& _funDef)
{
for (auto const& var: _funDef.returnVariables)
setValue(var.name, nullptr);
ASTWalker::operator()(_funDef);
}
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void SSAValueTracker::operator()(VariableDeclaration const& _varDecl)
{
if (!_varDecl.value)
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for (auto const& var: _varDecl.variables)
setValue(var.name, nullptr);
else if (_varDecl.variables.size() == 1)
setValue(_varDecl.variables.front().name, _varDecl.value.get());
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}
set<YulString> SSAValueTracker::ssaVariables(Block const& _ast)
{
SSAValueTracker t;
t(_ast);
set<YulString> ssaVars;
for (auto const& value: t.values())
ssaVars.insert(value.first);
return ssaVars;
}
void SSAValueTracker::setValue(YulString _name, Expression const* _value)
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{
assertThrow(
m_values.count(_name) == 0,
OptimizerException,
"Source needs to be disambiguated."
);
if (!_value)
_value = &m_zero;
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m_values[_name] = _value;
}