solidity/libyul/optimiser/EquivalentFunctionDetector.h

72 lines
2.1 KiB
C++

/*
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/>.
*/
/**
* Optimiser component that combines syntactically equivalent functions.
*/
#pragma once
#include <libyul/optimiser/ASTWalker.h>
#include <libyul/AsmDataForward.h>
namespace yul
{
/**
* Optimiser component that detects syntactically equivalent functions.
*
* Prerequisite: Disambiguator
*/
class EquivalentFunctionDetector: public ASTWalker
{
public:
static std::map<YulString, FunctionDefinition const*> run(Block& _block)
{
EquivalentFunctionDetector detector{};
detector(_block);
return std::move(detector.m_duplicates);
}
using ASTWalker::operator();
void operator()(FunctionDefinition const& _fun) override;
private:
EquivalentFunctionDetector() = default;
/**
* Fast heuristic to detect distinct, resp. potentially equal functions.
*
* Defines a partial order on function definitions. If two functions
* are comparable (one is "less" than the other), they are distinct.
* If not (neither is "less" than the other), they are *potentially* equal.
*/
class RoughHeuristic
{
public:
RoughHeuristic(FunctionDefinition const& _fun): m_fun(_fun) {}
bool operator<(RoughHeuristic const& _rhs) const;
private:
std::size_t codeSize() const;
FunctionDefinition const& m_fun;
mutable boost::optional<std::size_t> m_codeSize;
// In case the heuristic doesn't turn out to be good enough, we might want to define a hash function for code blocks.
};
std::map<RoughHeuristic, std::vector<FunctionDefinition const*>> m_candidates;
std::map<YulString, FunctionDefinition const*> m_duplicates;
};
}