libyul/optimiser/VarDeclInitializer.cpp


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/*
    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/>.
*/

#include <libyul/optimiser/VarDeclInitializer.h>
#include <libyul/AsmData.h>

#include <libdevcore/CommonData.h>
#include <libdevcore/Visitor.h>

using namespace std;
using namespace dev;
using namespace yul;

void VarDeclInitializer::operator()(Block& _block)
{
    ASTModifier::operator()(_block);

    static Expression const zero{Literal{{}, LiteralKind::Number, YulString{"0"}, {}}};

    using OptionalStatements = boost::optional<vector<Statement>>;
    GenericFallbackReturnsVisitor<OptionalStatements, VariableDeclaration> visitor{
        [](VariableDeclaration& _varDecl) -> OptionalStatements
        {
            if (_varDecl.value)
                return {};
            else if (_varDecl.variables.size() == 1)
            {
                _varDecl.value = make_shared<Expression>(zero);
                return {};
            }
            else
            {
                OptionalStatements ret{vector<Statement>{}};
                langutil::SourceLocation loc{std::move(_varDecl.location)};
                for (auto& var: _varDecl.variables)
                    ret->push_back(VariableDeclaration{loc, {std::move(var)}, make_shared<Expression>(zero)});
                return ret;
            }
        }
    };
    iterateReplacing(_block.statements, boost::apply_visitor(visitor));
}