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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/>.
*/
/**
* Optimisation stage that replaces variables by their most recently assigned expressions.
*/
#pragma once
#include <libyul/optimiser/DataFlowAnalyzer.h>
namespace yul
{
/**
* Optimisation stage that replaces variables by their most recently assigned expressions,
* but only if the expression is movable and one of the following holds:
* - the variable is referenced exactly once
* - the value is extremely cheap ("cost" of zero like ``caller()``)
* - the variable is referenced at most 5 times and the value is rather cheap
* ("cost" of at most 1 like a constant up to 0xff)
*
* Prerequisite: Disambiguator
*/
class Rematerialiser: public DataFlowAnalyzer
{
public:
static void run(Dialect const& _dialect, Block& _ast);
protected:
Rematerialiser(Dialect const& _dialect, Block& _ast);
using ASTModifier::visit;
void visit(Expression& _e) override;
std::map<YulString, size_t> m_referenceCounts;
};
}
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