mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
011f8d3ff7
Since the gas calculation can involve multiplication by ``--optimize-runs``, it is possible that `size_t` is not enough to represent the total gas.
110 lines
2.9 KiB
C++
110 lines
2.9 KiB
C++
/*
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This file is part of solidity.
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solidity is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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solidity is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with solidity. If not, see <http://www.gnu.org/licenses/>.
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*/
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// SPDX-License-Identifier: GPL-3.0
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/**
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* Optimisation stage that replaces constants by expressions that compute them.
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*/
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#pragma once
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#include <libyul/optimiser/ASTWalker.h>
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#include <libyul/YulString.h>
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#include <libyul/Dialect.h>
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#include <libyul/backends/evm/EVMDialect.h>
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#include <libyul/ASTForward.h>
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#include <liblangutil/SourceLocation.h>
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#include <libsolutil/Common.h>
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#include <tuple>
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#include <map>
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#include <memory>
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namespace solidity::yul
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{
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struct Dialect;
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class GasMeter;
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/**
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* Optimisation stage that replaces constants by expressions that compute them.
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*
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* Prerequisite: None
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*/
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class ConstantOptimiser: public ASTModifier
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{
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public:
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ConstantOptimiser(EVMDialect const& _dialect, GasMeter const& _meter):
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m_dialect(_dialect),
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m_meter(_meter)
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{}
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void visit(Expression& _e) override;
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struct Representation
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{
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std::unique_ptr<Expression> expression;
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bigint cost;
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};
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private:
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EVMDialect const& m_dialect;
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GasMeter const& m_meter;
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std::map<u256, Representation> m_cache;
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};
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class RepresentationFinder
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{
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public:
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using Representation = ConstantOptimiser::Representation;
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RepresentationFinder(
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EVMDialect const& _dialect,
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GasMeter const& _meter,
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langutil::SourceLocation _location,
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std::map<u256, Representation>& _cache
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):
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m_dialect(_dialect),
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m_meter(_meter),
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m_location(std::move(_location)),
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m_cache(_cache)
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{}
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/// @returns a cheaper representation for the number than its representation
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/// as a literal or nullptr otherwise.
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Expression const* tryFindRepresentation(u256 const& _value);
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private:
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/// Recursively try to find the cheapest representation of the given number,
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/// literal if necessary.
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Representation const& findRepresentation(u256 const& _value);
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Representation represent(u256 const& _value) const;
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Representation represent(YulString _instruction, Representation const& _arg) const;
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Representation represent(YulString _instruction, Representation const& _arg1, Representation const& _arg2) const;
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Representation min(Representation _a, Representation _b);
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EVMDialect const& m_dialect;
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GasMeter const& m_meter;
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langutil::SourceLocation m_location;
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/// Counter for the complexity of optimization, will stop when it reaches zero.
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size_t m_maxSteps = 10000;
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std::map<u256, Representation>& m_cache;
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};
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}
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