SSA value tracker.

This commit is contained in:
chriseth 2018-10-02 18:07:36 +02:00
parent 348112f0ab
commit 76db0d69cf
2 changed files with 111 additions and 0 deletions

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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/>.
*/
/**
* Component that collects variables that are never assigned to and their
* initial values.
*/
#include <libyul/optimiser/SSAValueTracker.h>
#include <libsolidity/inlineasm/AsmData.h>
using namespace std;
using namespace dev;
using namespace dev::yul;
void SSAValueTracker::operator()(Assignment const& _assignment)
{
for (auto const& var: _assignment.variableNames)
m_values.erase(var.name);
}
void SSAValueTracker::operator()(VariableDeclaration const& _varDecl)
{
if (_varDecl.variables.size() == 1)
setValue(_varDecl.variables.front().name, _varDecl.value.get());
else
for (auto const& var: _varDecl.variables)
setValue(var.name, nullptr);
}
void SSAValueTracker::setValue(string const& _name, Expression const* _value)
{
assertThrow(
m_values.count(_name) == 0,
OptimizerException,
"Source needs to be disambiguated."
);
m_values[_name] = _value;
}

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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/>.
*/
/**
* Component that collects variables that are never assigned to and their
* initial values.
*/
#pragma once
#include <libyul/optimiser/ASTWalker.h>
#include <string>
#include <map>
#include <set>
namespace dev
{
namespace yul
{
/**
* Class that walks the AST and stores the initial value of each variable
* that is never assigned to.
*
* Prerequisite: Disambiguator
*/
class SSAValueTracker: public ASTWalker
{
public:
using ASTWalker::operator();
virtual void operator()(VariableDeclaration const& _varDecl) override;
virtual void operator()(Assignment const& _assignment) override;
std::map<std::string, Expression const*> const& values() const { return m_values; }
Expression const* value(std::string const& _name) const { return m_values.at(_name); }
private:
void setValue(std::string const& _name, Expression const* _value);
std::map<std::string, Expression const*> m_values;
};
}
}