/*

  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

/**

 * Optimization stage that removes functions that call each other but are

 * otherwise unreferenced.

 *

 *  Prerequisites: Disambiguator, FunctionHoister.

 */

#pragma once

#include <libyul/optimiser/ASTWalker.h>

#include <libyul/optimiser/CallGraphGenerator.h>

#include <libyul/optimiser/OptimiserStep.h>

namespace solidity::yul

{

/**

 * Optimization stage that removes functions that call each other but are

 * neither externally referenced nor referenced from the outermost context.

 */

class CircularReferencesPruner: public ASTModifier

{

public:

  static constexpr char const* name{"CircularReferencesPruner"};

  static void run(OptimiserStepContext& _context, Block& _ast);

  using ASTModifier::operator();

  void operator()(Block& _block) override;

private:

  CircularReferencesPruner(std::set<YulString> const& _reservedIdentifiers):

    m_reservedIdentifiers(_reservedIdentifiers)

  {}

  /// Run a breadth-first search starting from the outermost context and

  /// externally referenced functions to find all the functions that are

  /// called from there either directly or indirectly.

  std::set<YulString> functionsCalledFromOutermostContext(CallGraph const& _callGraph);

  std::set<YulString> const& m_reservedIdentifiers;

};

}