mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
122 lines
3.5 KiB
C++
122 lines
3.5 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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#include <libyul/optimiser/SSAReverser.h>
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#include <libyul/optimiser/Metrics.h>
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#include <libyul/AsmData.h>
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#include <libsolutil/CommonData.h>
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#include <variant>
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using namespace std;
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using namespace solidity;
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using namespace solidity::yul;
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void SSAReverser::run(OptimiserStepContext&, Block& _block)
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{
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AssignmentCounter assignmentCounter;
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assignmentCounter(_block);
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SSAReverser{assignmentCounter}(_block);
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}
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void SSAReverser::operator()(Block& _block)
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{
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walkVector(_block.statements);
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util::iterateReplacingWindow<2>(
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_block.statements,
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[&](Statement& _stmt1, Statement& _stmt2) -> std::optional<vector<Statement>>
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{
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auto* varDecl = std::get_if<VariableDeclaration>(&_stmt1);
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if (!varDecl || varDecl->variables.size() != 1 || !varDecl->value)
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return {};
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// Replaces
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// let a_1 := E
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// a := a_1
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// with
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// a := E
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// let a_1 := a
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if (auto* assignment = std::get_if<Assignment>(&_stmt2))
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{
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auto* identifier = std::get_if<Identifier>(assignment->value.get());
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if (
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assignment->variableNames.size() == 1 &&
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identifier &&
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identifier->name == varDecl->variables.front().name
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)
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{
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// in the special case a == a_1, just remove the assignment
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if (assignment->variableNames.front().name == identifier->name)
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return util::make_vector<Statement>(std::move(_stmt1));
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else
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return util::make_vector<Statement>(
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Assignment{
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std::move(assignment->location),
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assignment->variableNames,
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std::move(varDecl->value)
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},
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VariableDeclaration{
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std::move(varDecl->location),
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std::move(varDecl->variables),
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std::make_unique<Expression>(std::move(assignment->variableNames.front()))
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}
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);
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}
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}
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// Replaces
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// let a_1 := E
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// let a := a_1
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// with
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// let a := E
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// let a_1 := a
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else if (auto* varDecl2 = std::get_if<VariableDeclaration>(&_stmt2))
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{
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auto* identifier = std::get_if<Identifier>(varDecl2->value.get());
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if (
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varDecl2->variables.size() == 1 &&
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identifier &&
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identifier->name == varDecl->variables.front().name && (
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m_assignmentCounter.assignmentCount(varDecl2->variables.front().name) >
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m_assignmentCounter.assignmentCount(varDecl->variables.front().name)
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)
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)
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{
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auto varIdentifier2 = std::make_unique<Expression>(Identifier{
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varDecl2->variables.front().location,
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varDecl2->variables.front().name
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});
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return util::make_vector<Statement>(
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VariableDeclaration{
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std::move(varDecl2->location),
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std::move(varDecl2->variables),
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std::move(varDecl->value)
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},
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VariableDeclaration{
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std::move(varDecl->location),
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std::move(varDecl->variables),
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std::move(varIdentifier2)
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}
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);
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}
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}
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return {};
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}
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);
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}
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