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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/>.
*/
#include <libyul/optimiser/SSAReverser.h>
#include <libyul/optimiser/Metrics.h>
#include <libyul/AsmData.h>
#include <libdevcore/CommonData.h>
using namespace std;
using namespace dev;
using namespace yul;
void SSAReverser::run(Block& _block)
{
AssignmentCounter assignmentCounter;
assignmentCounter(_block);
SSAReverser{assignmentCounter}(_block);
}
void SSAReverser::operator()(Block& _block)
{
walkVector(_block.statements);
iterateReplacingWindow<2>(
_block.statements,
[&](Statement& _stmt1, Statement& _stmt2) -> boost::optional<vector<Statement>>
{
auto* varDecl = boost::get<VariableDeclaration>(&_stmt1);
if (!varDecl || varDecl->variables.size() != 1 || !varDecl->value)
return {};
// Replaces
// let a_1 := E
// a := a_1
// with
// a := E
// let a_1 := a
if (auto* assignment = boost::get<Assignment>(&_stmt2))
{
auto* identifier = boost::get<Identifier>(assignment->value.get());
if (
assignment->variableNames.size() == 1 &&
identifier &&
identifier->name == varDecl->variables.front().name
)
{
vector<Statement> result;
result.emplace_back(Assignment{
std::move(assignment->location),
assignment->variableNames,
std::move(varDecl->value)
});
result.emplace_back(VariableDeclaration{
std::move(varDecl->location),
std::move(varDecl->variables),
std::make_unique<Expression>(std::move(assignment->variableNames.front()))
});
return { std::move(result) };
}
}
// Replaces
// let a_1 := E
// let a := a_1
// with
// let a := E
// let a_1 := a
else if (auto* varDecl2 = boost::get<VariableDeclaration>(&_stmt2))
{
auto* identifier = boost::get<Identifier>(varDecl2->value.get());
if (
varDecl2->variables.size() == 1 &&
identifier &&
identifier->name == varDecl->variables.front().name && (
m_assignmentCounter.assignmentCount(varDecl2->variables.front().name) >
m_assignmentCounter.assignmentCount(varDecl->variables.front().name)
)
)
{
vector<Statement> result;
auto varIdentifier2 = std::make_unique<Expression>(Identifier{
varDecl2->variables.front().location,
varDecl2->variables.front().name
});
result.emplace_back(VariableDeclaration{
std::move(varDecl2->location),
std::move(varDecl2->variables),
std::move(varDecl->value)
});
result.emplace_back(VariableDeclaration{
std::move(varDecl->location),
std::move(varDecl->variables),
std::move(varIdentifier2)
});
return { std::move(result) };
}
}
return {};
}
);
}
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