/* 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 . */ /** * Module for applying replacement rules against Expressions. */ #include #include #include #include #include #include #include #include using namespace std; using namespace dev; using namespace dev::eth; using namespace langutil; using namespace yul; SimplificationRule const* SimplificationRules::findFirstMatch( Expression const& _expr, Dialect const& _dialect, map const& _ssaValues ) { auto instruction = instructionAndArguments(_dialect, _expr); if (!instruction) return nullptr; static SimplificationRules rules; assertThrow(rules.isInitialized(), OptimizerException, "Rule list not properly initialized."); for (auto const& rule: rules.m_rules[uint8_t(instruction->first)]) { rules.resetMatchGroups(); if (rule.pattern.matches(_expr, _dialect, _ssaValues)) if (!rule.feasible || rule.feasible()) return &rule; } return nullptr; } bool SimplificationRules::isInitialized() const { return !m_rules[uint8_t(dev::eth::Instruction::ADD)].empty(); } std::optional const*>> SimplificationRules::instructionAndArguments(Dialect const& _dialect, Expression const& _expr) { if (_expr.type() == typeid(FunctionalInstruction)) return make_pair(boost::get(_expr).instruction, &boost::get(_expr).arguments); else if (_expr.type() == typeid(FunctionCall)) if (auto const* dialect = dynamic_cast(&_dialect)) if (auto const* builtin = dialect->builtin(boost::get(_expr).functionName.name)) if (builtin->instruction) return make_pair(*builtin->instruction, &boost::get(_expr).arguments); return {}; } void SimplificationRules::addRules(vector> const& _rules) { for (auto const& r: _rules) addRule(r); } void SimplificationRules::addRule(SimplificationRule const& _rule) { m_rules[uint8_t(_rule.pattern.instruction())].push_back(_rule); } SimplificationRules::SimplificationRules() { // Multiple occurrences of one of these inside one rule must match the same equivalence class. // Constants. Pattern A(PatternKind::Constant); Pattern B(PatternKind::Constant); Pattern C(PatternKind::Constant); // Anything. Pattern W; Pattern X; Pattern Y; Pattern Z; A.setMatchGroup(1, m_matchGroups); B.setMatchGroup(2, m_matchGroups); C.setMatchGroup(3, m_matchGroups); W.setMatchGroup(4, m_matchGroups); X.setMatchGroup(5, m_matchGroups); Y.setMatchGroup(6, m_matchGroups); Z.setMatchGroup(7, m_matchGroups); addRules(simplificationRuleList(A, B, C, W, X, Y, Z)); assertThrow(isInitialized(), OptimizerException, "Rule list not properly initialized."); } yul::Pattern::Pattern(dev::eth::Instruction _instruction, vector const& _arguments): m_kind(PatternKind::Operation), m_instruction(_instruction), m_arguments(_arguments) { } void Pattern::setMatchGroup(unsigned _group, map& _matchGroups) { m_matchGroup = _group; m_matchGroups = &_matchGroups; } bool Pattern::matches( Expression const& _expr, Dialect const& _dialect, map const& _ssaValues ) const { Expression const* expr = &_expr; // Resolve the variable if possible. // Do not do it for "Any" because we can check identity better for variables. if (m_kind != PatternKind::Any && _expr.type() == typeid(Identifier)) { YulString varName = boost::get(_expr).name; if (_ssaValues.count(varName)) if (Expression const* new_expr = _ssaValues.at(varName)) expr = new_expr; } assertThrow(expr, OptimizerException, ""); if (m_kind == PatternKind::Constant) { if (expr->type() != typeid(Literal)) return false; Literal const& literal = boost::get(*expr); if (literal.kind != LiteralKind::Number) return false; if (m_data && *m_data != u256(literal.value.str())) return false; assertThrow(m_arguments.empty(), OptimizerException, ""); } else if (m_kind == PatternKind::Operation) { auto instrAndArgs = SimplificationRules::instructionAndArguments(_dialect, *expr); if (!instrAndArgs || m_instruction != instrAndArgs->first) return false; assertThrow(m_arguments.size() == instrAndArgs->second->size(), OptimizerException, ""); for (size_t i = 0; i < m_arguments.size(); ++i) if (!m_arguments[i].matches(instrAndArgs->second->at(i), _dialect, _ssaValues)) return false; } else { assertThrow(m_arguments.empty(), OptimizerException, "\"Any\" should not have arguments."); } if (m_matchGroup) { // We support matching multiple expressions that require the same value // based on identical ASTs, which have to be movable. // TODO: add tests: // - { let x := mload(0) let y := and(x, x) } // - { let x := 4 let y := and(x, y) } // This code uses `_expr` again for "Any", because we want the comparison to be done // on the variables and not their values. // The assumption is that CSE or local value numbering has been done prior to this step. if (m_matchGroups->count(m_matchGroup)) { assertThrow(m_kind == PatternKind::Any, OptimizerException, "Match group repetition for non-any."); Expression const* firstMatch = (*m_matchGroups)[m_matchGroup]; assertThrow(firstMatch, OptimizerException, "Match set but to null."); return SyntacticallyEqual{}(*firstMatch, _expr) && SideEffectsCollector(_dialect, _expr).movable(); } else if (m_kind == PatternKind::Any) (*m_matchGroups)[m_matchGroup] = &_expr; else { assertThrow(m_kind == PatternKind::Constant, OptimizerException, "Match group set for operation."); // We do not use _expr here, because we want the actual number. (*m_matchGroups)[m_matchGroup] = expr; } } return true; } dev::eth::Instruction Pattern::instruction() const { assertThrow(m_kind == PatternKind::Operation, OptimizerException, ""); return m_instruction; } Expression Pattern::toExpression(SourceLocation const& _location) const { if (matchGroup()) return ASTCopier().translate(matchGroupValue()); if (m_kind == PatternKind::Constant) { assertThrow(m_data, OptimizerException, "No match group and no constant value given."); return Literal{_location, LiteralKind::Number, YulString{formatNumber(*m_data)}, {}}; } else if (m_kind == PatternKind::Operation) { vector arguments; for (auto const& arg: m_arguments) arguments.emplace_back(arg.toExpression(_location)); // TODO convert to FunctionCall return FunctionalInstruction{_location, m_instruction, std::move(arguments)}; } assertThrow(false, OptimizerException, "Pattern of kind 'any', but no match group."); } u256 Pattern::d() const { return valueOfNumberLiteral(boost::get(matchGroupValue())); } Expression const& Pattern::matchGroupValue() const { assertThrow(m_matchGroup > 0, OptimizerException, ""); assertThrow(!!m_matchGroups, OptimizerException, ""); assertThrow((*m_matchGroups)[m_matchGroup], OptimizerException, ""); return *(*m_matchGroups)[m_matchGroup]; }