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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.
*/
#include <libjulia/optimiser/Rematerialiser.h>
#include <libjulia/optimiser/ASTCopier.h>
#include <libjulia/optimiser/NameCollector.h>
#include <libsolidity/inlineasm/AsmData.h>
#include <libjulia/optimiser/Semantics.h>
#include <libdevcore/CommonData.h>
#include <boost/range/adaptor/reversed.hpp>
using namespace std;
using namespace dev;
using namespace dev::julia;
void Rematerialiser::operator()(Assignment& _assignment)
{
set<string> names;
for (auto const& var: _assignment.variableNames)
names.insert(var.name);
handleAssignment(names, _assignment.value.get());
}
void Rematerialiser::operator()(VariableDeclaration& _varDecl)
{
set<string> names;
for (auto const& var: _varDecl.variables)
names.insert(var.name);
m_variableScopes.back().first += names;
handleAssignment(names, _varDecl.value.get());
}
void Rematerialiser::operator()(If& _if)
{
ASTModifier::operator()(_if);
Assignments ass;
ass(_if.body);
handleAssignment(ass.names(), nullptr);
}
void Rematerialiser::operator()(Switch& _switch)
{
boost::apply_visitor(*this, *_switch.expression);
set<string> assignedVariables;
for (auto& _case: _switch.cases)
{
(*this)(_case.body);
Assignments ass;
ass(_case.body);
assignedVariables += ass.names();
// This is a little too destructive, we could retain the old replacements.
handleAssignment(ass.names(), nullptr);
}
handleAssignment(assignedVariables, nullptr);
}
void Rematerialiser::operator()(FunctionDefinition& _fun)
{
m_variableScopes.push_back(make_pair(set<string>(), true));
for (auto const& parameter: _fun.parameters)
m_variableScopes.back().first.insert(parameter.name);
for (auto const& var: _fun.returnVariables)
m_variableScopes.back().first.insert(var.name);
ASTModifier::operator()(_fun);
m_variableScopes.pop_back();
}
void Rematerialiser::operator()(ForLoop& _for)
{
// Special scope handling of the pre block.
m_variableScopes.push_back(make_pair(set<string>(), false));
for (auto& statement: _for.pre.statements)
visit(statement);
Assignments ass;
ass(_for.body);
ass(_for.post);
handleAssignment(ass.names(), nullptr);
visit(*_for.condition);
(*this)(_for.body);
(*this)(_for.post);
handleAssignment(ass.names(), nullptr);
m_variableScopes.pop_back();
}
void Rematerialiser::operator()(Block& _block)
{
size_t numScopes = m_variableScopes.size();
m_variableScopes.push_back(make_pair(set<string>(), false));
ASTModifier::operator()(_block);
m_variableScopes.pop_back();
solAssert(numScopes == m_variableScopes.size(), "");
}
void Rematerialiser::handleAssignment(set<string> const& _variables, Expression* _value)
{
MovableChecker movableChecker;
if (_value)
{
visit(*_value);
movableChecker.visit(*_value);
}
if (_variables.size() == 1)
{
string const& name = *_variables.begin();
if (movableChecker.movable() && _value)
// TODO Plus heuristic about size of value
// TODO If _value is null, we could use zero.
m_substitutions[name] = _value;
else
m_substitutions.erase(name);
}
else
for (auto const& name: _variables)
m_substitutions.erase(name);
// Disallow substitutions that use a variable that will be reassigned by this assignment.
for (auto const& name: _variables)
for (auto const& ref: m_referencedBy[name])
m_substitutions.erase(ref);
// Update the fact which variables are referenced by the newly assigned variables
for (auto const& name: _variables)
{
for (auto const& ref: m_references[name])
m_referencedBy[ref].erase(name);
m_references[name].clear();
}
auto const& referencedVariables = movableChecker.referencedVariables();
for (auto const& name: _variables)
{
m_references[name] = referencedVariables;
for (auto const& ref: referencedVariables)
m_referencedBy[ref].insert(name);
}
}
bool Rematerialiser::inScope(string const& _variableName) const
{
for (auto const& scope: m_variableScopes | boost::adaptors::reversed)
{
if (scope.first.count(_variableName))
return true;
if (scope.second)
return false;
}
return false;
}
void Rematerialiser::visit(Expression& _e)
{
if (_e.type() == typeid(Identifier))
{
Identifier& identifier = boost::get<Identifier>(_e);
if (m_substitutions.count(identifier.name))
{
string name = identifier.name;
bool doSubstitute = true;
for (auto const& ref: m_references[name])
if (!inScope(ref))
{
doSubstitute = false;
break;
}
if (doSubstitute)
_e = (ASTCopier{}).translate(*m_substitutions.at(name));
}
}
ASTModifier::visit(_e);
}
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