/*

  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

#include <libyul/backends/evm/ssa/analysis/ReducibilityCheck.h>

#include <libyul/backends/evm/ssa/analysis/DepthFirstSpanningTree.h>

#include <libyul/backends/evm/ssa/analysis/DominatorTree.h>

using namespace solidity::yul::ssa;

using namespace solidity::yul::ssa::analysis;

bool analysis::isReducibleCFG(DepthFirstSpanningTree const& _dfsTree)

{

  DominatorTree const dominatorTree(_dfsTree);

  for (auto const src: _dfsTree.preOrder())

  {

    bool reducible = true;

    _dfsTree.cfg().block(src).forEachExit([&](SSACFG::BlockId const& _target) {

      if (

        _dfsTree.ancestor(_target, src) &&

        !dominatorTree.dominates(_target, src)

      )

        reducible = false;

    });

    if (!reducible)

      return false;

  }

  return true;

}