/*

  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/>.

*/

// SPDX-License-Identifier: GPL-3.0

/**

 * Component that collects variables that are never assigned to and their

 * initial values.

 */

#include <libyul/optimiser/SSAValueTracker.h>

#include <libyul/AST.h>

using namespace std;

using namespace solidity;

using namespace solidity::yul;

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);

}

void SSAValueTracker::operator()(VariableDeclaration const& _varDecl)

{

  if (!_varDecl.value)

    for (auto const& var: _varDecl.variables)

      setValue(var.name, nullptr);

  else if (_varDecl.variables.size() == 1)

    setValue(_varDecl.variables.front().name, _varDecl.value.get());

}

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)

{

  assertThrow(

    m_values.count(_name) == 0,

    OptimizerException,

    "Source needs to be disambiguated."

  );

  if (!_value)

    _value = &m_zero;

  m_values[_name] = _value;

}