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>

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

void SSAValueTracker::operator()(Assignment const& _assignment)
{
    for (auto const& var: _assignment.variableNames)
        m_values.erase(var.name);
}

void SSAValueTracker::operator()(VariableDeclaration const& _varDecl)
{
    static Expression const zero{Literal{{}, LiteralKind::Number, YulString{"0"}, {}}};
    if (!_varDecl.value)
        for (auto const& var: _varDecl.variables)
            setValue(var.name, &zero);
    else if (_varDecl.variables.size() == 1)
        setValue(_varDecl.variables.front().name, _varDecl.value.get());
}

void SSAValueTracker::setValue(YulString _name, Expression const* _value)
{
    assertThrow(
        m_values.count(_name) == 0,
        OptimizerException,
        "Source needs to be disambiguated."
    );
    m_values[_name] = _value;
}