/*

  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

#pragma once

#include <libyul/optimiser/ASTWalker.h>

#include <libyul/optimiser/OptimiserStep.h>

#include <libyul/ASTForward.h>

#include <libyul/Dialect.h>

#include <libsolutil/Common.h>

namespace solidity::yul

{

/**

 * Conditional simplifier.

 *

 * Inserts assignments to condition variables if the value can be determined

 * from the control-flow.

 *

 * Destroys SSA form.

 *

 * Currently, this tool is very limited, mostly because we do not yet have support

 * for boolean types. Since conditions only check for expressions being nonzero,

 * we cannot assign a specific value.

 *

 * Current features:

 *  - switch cases: insert "<condition> := <caseLabel>"

 *  - after if statement with terminating control-flow, insert "<condition> := 0"

 *

 * Future features:

 *  - allow replacements by "1"

 *

 * Works best with SSA form and if dead code removal has run before.

 *

 * Prerequisite: Disambiguator.

 */

class ConditionalSimplifier: public ASTModifier

{

public:

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

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

  using ASTModifier::operator();

  void operator()(Switch& _switch) override;

  void operator()(Block& _block) override;

private:

  explicit ConditionalSimplifier(

    Dialect const& _dialect,

    std::map<YulString, ControlFlowSideEffects> _sideEffects

  ):

    m_dialect(_dialect), m_functionSideEffects(move(_sideEffects))

  {}

  Dialect const& m_dialect;

  std::map<YulString, ControlFlowSideEffects> m_functionSideEffects;

};

}