mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
139 lines
4.2 KiB
C++
139 lines
4.2 KiB
C++
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/*
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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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#include <libyul/optimiser/StructuralSimplifier.h>
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#include <libyul/optimiser/Semantics.h>
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#include <libyul/optimiser/Utilities.h>
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#include <libyul/AsmData.h>
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#include <libdevcore/CommonData.h>
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#include <libdevcore/Visitor.h>
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using namespace std;
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using namespace dev;
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using namespace yul;
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namespace {
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ExpressionStatement makePopExpressionStatement(langutil::SourceLocation const& _location, Expression&& _expression)
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{
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return {_location, FunctionalInstruction{
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_location,
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solidity::Instruction::POP,
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{std::move(_expression)}
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}};
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}
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}
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void StructuralSimplifier::operator()(Block& _block)
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{
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pushScope(false);
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simplify(_block.statements);
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popScope();
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}
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void StructuralSimplifier::simplify(std::vector<yul::Statement>& _statements)
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{
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using OptionalStatements = boost::optional<vector<Statement>>;
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GenericFallbackReturnsVisitor<OptionalStatements, If, Switch, ForLoop> const visitor(
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[&](If& _ifStmt) -> OptionalStatements {
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if (_ifStmt.body.statements.empty())
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return {{makePopExpressionStatement(_ifStmt.location, std::move(*_ifStmt.condition))}};
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if (expressionAlwaysTrue(*_ifStmt.condition))
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return {std::move(_ifStmt.body.statements)};
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else if (expressionAlwaysFalse(*_ifStmt.condition))
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return {{}};
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return {};
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},
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[](Switch& _switchStmt) -> OptionalStatements {
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if (_switchStmt.cases.size() == 1)
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{
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auto& switchCase = _switchStmt.cases.front();
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auto loc = locationOf(*_switchStmt.expression);
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if (switchCase.value)
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return {{If{
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std::move(_switchStmt.location),
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make_shared<Expression>(FunctionalInstruction{
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std::move(loc),
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solidity::Instruction::EQ,
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{std::move(*switchCase.value), std::move(*_switchStmt.expression)}
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}), std::move(switchCase.body)}}};
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else
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return {{
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makePopExpressionStatement(loc, std::move(*_switchStmt.expression)),
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std::move(switchCase.body)
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}};
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}
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else
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return {};
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},
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[&](ForLoop& _forLoop) -> OptionalStatements {
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if (expressionAlwaysFalse(*_forLoop.condition))
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return {std::move(_forLoop.pre.statements)};
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else
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return {};
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}
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);
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iterateReplacing(
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_statements,
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[&](Statement& _stmt) -> OptionalStatements
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{
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visit(_stmt);
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OptionalStatements result = boost::apply_visitor(visitor, _stmt);
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if (result)
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simplify(*result);
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return result;
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}
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);
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}
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bool StructuralSimplifier::expressionAlwaysTrue(Expression const& _expression)
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{
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return boost::apply_visitor(GenericFallbackReturnsVisitor<bool, Identifier const, Literal const>(
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[&](Identifier const& _identifier) -> bool {
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if (auto expr = m_value[_identifier.name])
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return expressionAlwaysTrue(*expr);
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return false;
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},
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[](Literal const& _literal) -> bool {
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static YulString const trueString("true");
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return
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(_literal.kind == LiteralKind::Boolean && _literal.value == trueString) ||
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(_literal.kind == LiteralKind::Number && valueOfNumberLiteral(_literal) != u256(0))
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;
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}
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), _expression);
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}
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bool StructuralSimplifier::expressionAlwaysFalse(Expression const& _expression)
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{
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return boost::apply_visitor(GenericFallbackReturnsVisitor<bool, Identifier const, Literal const>(
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[&](Identifier const& _identifier) -> bool {
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if (auto expr = m_value[_identifier.name])
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return expressionAlwaysFalse(*expr);
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return false;
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},
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[](Literal const& _literal) -> bool {
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static YulString const falseString("false");
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return
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(_literal.kind == LiteralKind::Boolean && _literal.value == falseString) ||
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(_literal.kind == LiteralKind::Number && valueOfNumberLiteral(_literal) == u256(0))
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;
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}
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), _expression);
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}
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