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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/>.
*/
// SPDX-License-Identifier: GPL-3.0
/**
* Optimisation stage that replaces expressions known to be the current value of a variable
* in scope by a reference to that variable.
*/
#pragma once
#include <libyul/optimiser/DataFlowAnalyzer.h>
#include <libyul/optimiser/OptimiserStep.h>
#include <set>
namespace solidity::yul
{
struct Dialect;
struct SideEffects;
/**
* Optimisation stage that replaces expressions known to be the current value of a variable
* in scope by a reference to that variable.
*
* Prerequisite: Disambiguator, ForLoopInitRewriter.
*/
class CommonSubexpressionEliminator: public DataFlowAnalyzer
{
public:
static constexpr char const* name{"CommonSubexpressionEliminator"};
static void run(OptimiserStepContext&, Block& _ast);
using DataFlowAnalyzer::operator();
void operator()(FunctionDefinition&) override;
private:
CommonSubexpressionEliminator(
Dialect const& _dialect,
std::map<YulString, SideEffects> _functionSideEffects
);
protected:
using ASTModifier::visit;
void visit(Expression& _e) override;
private:
std::set<YulString> m_returnVariables;
};
}