2018-12-03 16:19:37 +00:00
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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/AsmData.h>
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2019-01-15 12:40:10 +00:00
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#include <libyul/Utilities.h>
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2020-01-06 10:52:23 +00:00
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#include <libsolutil/CommonData.h>
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#include <libsolutil/Visitor.h>
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2018-12-03 16:19:37 +00:00
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2019-03-05 18:49:34 +00:00
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#include <boost/range/algorithm_ext/erase.hpp>
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2018-12-03 16:19:37 +00:00
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using namespace std;
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2019-12-11 16:31:36 +00:00
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using namespace solidity;
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using namespace solidity::yul;
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2018-12-03 16:19:37 +00:00
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2019-10-28 10:39:30 +00:00
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using OptionalStatements = std::optional<vector<Statement>>;
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2019-03-06 10:33:02 +00:00
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2018-12-03 16:19:37 +00:00
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namespace {
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2019-03-06 10:33:02 +00:00
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OptionalStatements replaceConstArgSwitch(Switch& _switchStmt, u256 const& _constExprVal)
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{
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Block* matchingCaseBlock = nullptr;
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Case* defaultCase = nullptr;
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for (auto& _case: _switchStmt.cases)
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{
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if (_case.value && valueOfLiteral(*_case.value) == _constExprVal)
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{
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matchingCaseBlock = &_case.body;
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break;
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}
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else if (!_case.value)
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defaultCase = &_case;
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}
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if (!matchingCaseBlock && defaultCase)
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matchingCaseBlock = &defaultCase->body;
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if (matchingCaseBlock)
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return util::make_vector<Statement>(std::move(*matchingCaseBlock));
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else
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return optional<vector<Statement>>{vector<Statement>{}};
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}
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2018-12-03 16:19:37 +00:00
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}
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2019-09-23 14:32:50 +00:00
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void StructuralSimplifier::run(OptimiserStepContext&, Block& _ast)
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{
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StructuralSimplifier{}(_ast);
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}
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2018-12-03 16:19:37 +00:00
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void StructuralSimplifier::operator()(Block& _block)
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{
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simplify(_block.statements);
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2019-02-27 15:55:42 +00:00
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}
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2018-12-03 16:19:37 +00:00
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void StructuralSimplifier::simplify(std::vector<yul::Statement>& _statements)
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{
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util::GenericVisitor visitor{
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util::VisitorFallback<OptionalStatements>{},
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[&](If& _ifStmt) -> OptionalStatements {
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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 {vector<Statement>{}};
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2018-12-03 16:19:37 +00:00
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return {};
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},
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[&](Switch& _switchStmt) -> OptionalStatements {
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if (std::optional<u256> const constExprVal = hasLiteralValue(*_switchStmt.expression))
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return replaceConstArgSwitch(_switchStmt, constExprVal.value());
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2019-03-05 18:49:34 +00:00
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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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2019-05-09 19:56:56 +00:00
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return {};
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2018-12-03 16:19:37 +00:00
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}
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2019-11-24 17:46:43 +00:00
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};
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2019-12-11 16:31:36 +00:00
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util::iterateReplacing(
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_statements,
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[&](Statement& _stmt) -> OptionalStatements
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{
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2019-11-19 15:42:49 +00:00
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OptionalStatements result = std::visit(visitor, _stmt);
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2018-12-03 16:19:37 +00:00
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if (result)
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simplify(*result);
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2019-03-06 18:26:26 +00:00
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else
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visit(_stmt);
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2018-12-03 16:19:37 +00:00
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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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if (std::optional<u256> value = hasLiteralValue(_expression))
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2019-09-11 17:16:33 +00:00
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return *value != 0;
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else
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return false;
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2018-12-03 16:19:37 +00:00
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}
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bool StructuralSimplifier::expressionAlwaysFalse(Expression const& _expression)
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{
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if (std::optional<u256> value = hasLiteralValue(_expression))
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2019-09-11 17:16:33 +00:00
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return *value == 0;
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else
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return false;
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}
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2019-12-11 16:31:36 +00:00
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std::optional<u256> StructuralSimplifier::hasLiteralValue(Expression const& _expression) const
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{
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if (holds_alternative<Literal>(_expression))
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return valueOfLiteral(std::get<Literal>(_expression));
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else
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return std::optional<u256>();
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2018-12-03 16:19:37 +00:00
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}
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