/*

  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

/**

 * Optimiser component that uses the simplification rules to simplify expressions.

 */

#pragma once

#include <libyul/ASTForward.h>

#include <libyul/optimiser/DataFlowAnalyzer.h>

namespace solidity::yul

{

struct Dialect;

struct OptimiserStepContext;

/**

 * Applies simplification rules to all expressions.

 * The component will work best if the code is in SSA form, but

 * this is not required for correctness. Using CommonSubexpressionEliminator

 * also helps this component track equivalent sub-expressions.

 *

 * It tracks the current values of variables using the DataFlowAnalyzer

 * and takes them into account for replacements.

 *

 * Prerequisite: Disambiguator, ForLoopInitRewriter.

 */

class ExpressionSimplifier: public DataFlowAnalyzer

{

public:

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

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

  using ASTModifier::operator();

  void visit(Expression& _expression) override;

private:

  explicit ExpressionSimplifier(Dialect const& _dialect):

    DataFlowAnalyzer(_dialect, MemoryAndStorage::Ignore)

  {}

  bool knownToBeZero(Expression const& _expression) const;

};

}