/*

  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 performs function inlining.

 */

#pragma once

#include <libyul/optimiser/ASTWalker.h>

#include <libyul/ASTForward.h>

#include <optional>

#include <set>

namespace solidity::yul

{

struct Dialect;

struct OptimiserStepContext;

/**

 * Optimiser component that modifies an AST in place, inlining functions that can be

 * inlined inside functional expressions, i.e. functions that

 *  - return a single value

 *  - have a body like r := <functional expression>

 *  - neither reference themselves nor r in the right hand side

 *

 * Furthermore, for all parameters, all of the following need to be true

 *  - the argument is movable

 *  - the parameter is either referenced less than twice in the function body, or the argument is rather cheap

 *    ("cost" of at most 1 like a constant up to 0xff)

 *

 * This component can only be used on sources with unique names.

 */

class ExpressionInliner: public ASTModifier

{

public:

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

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

  using ASTModifier::operator();

  void operator()(FunctionDefinition& _fun) override;

  void visit(Expression& _expression) override;

private:

  ExpressionInliner(

    Dialect const& _dialect,

    std::map<YulString, FunctionDefinition const*> const& _inlinableFunctions

  ): m_dialect(_dialect), m_inlinableFunctions(_inlinableFunctions)

  {}

  Dialect const& m_dialect;

  std::map<YulString, FunctionDefinition const*> const& m_inlinableFunctions;

  std::map<YulString, YulString> m_varReplacements;

  /// Set of functions we are currently visiting inside.

  std::set<YulString> m_currentFunctions;

};

}