mirror of
https://github.com/ethereum/solidity
synced 2023-10-03 13:03:40 +00:00
276 lines
8.7 KiB
C++
276 lines
8.7 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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/**
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* Module for applying replacement rules against Expressions.
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*/
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#include <libyul/optimiser/SimplificationRules.h>
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#include <libyul/optimiser/ASTCopier.h>
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#include <libyul/optimiser/Semantics.h>
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#include <libyul/optimiser/SyntacticalEquality.h>
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#include <libyul/optimiser/DataFlowAnalyzer.h>
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#include <libyul/backends/evm/EVMDialect.h>
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#include <libyul/AST.h>
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#include <libyul/Utilities.h>
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#include <libevmasm/RuleList.h>
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using namespace std;
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using namespace solidity;
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using namespace solidity::evmasm;
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using namespace solidity::langutil;
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using namespace solidity::yul;
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SimplificationRules::Rule const* SimplificationRules::findFirstMatch(
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Expression const& _expr,
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Dialect const& _dialect,
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map<YulString, AssignedValue> const& _ssaValues
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)
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{
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auto instruction = instructionAndArguments(_dialect, _expr);
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if (!instruction)
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return nullptr;
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static std::map<std::optional<EVMVersion>, std::unique_ptr<SimplificationRules>> evmRules;
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std::optional<EVMVersion> version;
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if (yul::EVMDialect const* evmDialect = dynamic_cast<yul::EVMDialect const*>(&_dialect))
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version = evmDialect->evmVersion();
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if (!evmRules[version])
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evmRules[version] = std::make_unique<SimplificationRules>(version);
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SimplificationRules& rules = *evmRules[version];
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assertThrow(rules.isInitialized(), OptimizerException, "Rule list not properly initialized.");
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for (auto const& rule: rules.m_rules[uint8_t(instruction->first)])
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{
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rules.resetMatchGroups();
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if (rule.pattern.matches(_expr, _dialect, _ssaValues))
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if (!rule.feasible || rule.feasible())
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return &rule;
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}
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return nullptr;
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}
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bool SimplificationRules::isInitialized() const
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{
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return !m_rules[uint8_t(evmasm::Instruction::ADD)].empty();
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}
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std::optional<std::pair<evmasm::Instruction, vector<Expression> const*>>
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SimplificationRules::instructionAndArguments(Dialect const& _dialect, Expression const& _expr)
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{
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if (holds_alternative<FunctionCall>(_expr))
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if (auto const* dialect = dynamic_cast<EVMDialect const*>(&_dialect))
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if (auto const* builtin = dialect->builtin(std::get<FunctionCall>(_expr).functionName.name))
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if (builtin->instruction)
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return make_pair(*builtin->instruction, &std::get<FunctionCall>(_expr).arguments);
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return {};
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}
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void SimplificationRules::addRules(std::vector<Rule> const& _rules)
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{
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for (auto const& r: _rules)
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addRule(r);
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}
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void SimplificationRules::addRule(Rule const& _rule)
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{
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m_rules[uint8_t(_rule.pattern.instruction())].push_back(_rule);
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}
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SimplificationRules::SimplificationRules(std::optional<langutil::EVMVersion> _evmVersion)
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{
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// Multiple occurrences of one of these inside one rule must match the same equivalence class.
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// Constants.
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Pattern A(PatternKind::Constant);
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Pattern B(PatternKind::Constant);
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Pattern C(PatternKind::Constant);
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// Anything.
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Pattern W;
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Pattern X;
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Pattern Y;
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Pattern Z;
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A.setMatchGroup(1, m_matchGroups);
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B.setMatchGroup(2, m_matchGroups);
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C.setMatchGroup(3, m_matchGroups);
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W.setMatchGroup(4, m_matchGroups);
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X.setMatchGroup(5, m_matchGroups);
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Y.setMatchGroup(6, m_matchGroups);
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Z.setMatchGroup(7, m_matchGroups);
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addRules(simplificationRuleList(_evmVersion, A, B, C, W, X, Y, Z));
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assertThrow(isInitialized(), OptimizerException, "Rule list not properly initialized.");
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}
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yul::Pattern::Pattern(evmasm::Instruction _instruction, initializer_list<Pattern> _arguments):
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m_kind(PatternKind::Operation),
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m_instruction(_instruction),
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m_arguments(_arguments)
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{
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}
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void Pattern::setMatchGroup(unsigned _group, map<unsigned, Expression const*>& _matchGroups)
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{
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m_matchGroup = _group;
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m_matchGroups = &_matchGroups;
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}
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bool Pattern::matches(
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Expression const& _expr,
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Dialect const& _dialect,
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map<YulString, AssignedValue> const& _ssaValues
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) const
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{
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Expression const* expr = &_expr;
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// Resolve the variable if possible.
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// Do not do it for "Any" because we can check identity better for variables.
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if (m_kind != PatternKind::Any && holds_alternative<Identifier>(_expr))
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{
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YulString varName = std::get<Identifier>(_expr).name;
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if (_ssaValues.count(varName))
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if (Expression const* new_expr = _ssaValues.at(varName).value)
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expr = new_expr;
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}
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assertThrow(expr, OptimizerException, "");
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if (m_kind == PatternKind::Constant)
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{
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if (!holds_alternative<Literal>(*expr))
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return false;
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Literal const& literal = std::get<Literal>(*expr);
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if (literal.kind != LiteralKind::Number)
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return false;
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if (m_data && *m_data != u256(literal.value.str()))
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return false;
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assertThrow(m_arguments.empty(), OptimizerException, "");
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}
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else if (m_kind == PatternKind::Operation)
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{
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auto instrAndArgs = SimplificationRules::instructionAndArguments(_dialect, *expr);
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if (!instrAndArgs || m_instruction != instrAndArgs->first)
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return false;
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assertThrow(m_arguments.size() == instrAndArgs->second->size(), OptimizerException, "");
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for (size_t i = 0; i < m_arguments.size(); ++i)
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{
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Expression const& arg = instrAndArgs->second->at(i);
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// If this is a direct function call instead of a variable or literal,
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// we reject the match because side-effects could prevent us from
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// arbitrarily modifying the code.
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if (
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holds_alternative<FunctionCall>(arg) ||
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!m_arguments[i].matches(arg, _dialect, _ssaValues)
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)
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return false;
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}
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}
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else
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{
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assertThrow(m_arguments.empty(), OptimizerException, "\"Any\" should not have arguments.");
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assertThrow(!holds_alternative<FunctionCall>(*expr), OptimizerException, "\"Any\" at top-level.");
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}
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if (m_matchGroup)
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{
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// We support matching multiple expressions that require the same value
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// based on identical ASTs, which have to be movable.
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// TODO: add tests:
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// - { let x := mload(0) let y := and(x, x) }
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// - { let x := 4 let y := and(x, y) }
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// This code uses `_expr` again for "Any", because we want the comparison to be done
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// on the variables and not their values.
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// The assumption is that CSE or local value numbering has been done prior to this step.
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if (m_matchGroups->count(m_matchGroup))
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{
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assertThrow(m_kind == PatternKind::Any, OptimizerException, "Match group repetition for non-any.");
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Expression const* firstMatch = (*m_matchGroups)[m_matchGroup];
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assertThrow(firstMatch, OptimizerException, "Match set but to null.");
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assertThrow(
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!holds_alternative<FunctionCall>(_expr) &&
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!holds_alternative<FunctionCall>(*firstMatch),
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OptimizerException,
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"Group matches have to be literals or variables."
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);
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return SyntacticallyEqual{}(*firstMatch, _expr);
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}
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else if (m_kind == PatternKind::Any)
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(*m_matchGroups)[m_matchGroup] = &_expr;
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else
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{
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assertThrow(m_kind == PatternKind::Constant, OptimizerException, "Match group set for operation.");
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// We do not use _expr here, because we want the actual number.
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(*m_matchGroups)[m_matchGroup] = expr;
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}
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}
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return true;
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}
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evmasm::Instruction Pattern::instruction() const
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{
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assertThrow(m_kind == PatternKind::Operation, OptimizerException, "");
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return m_instruction;
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}
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Expression Pattern::toExpression(SourceLocation const& _location) const
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{
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if (matchGroup())
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return ASTCopier().translate(matchGroupValue());
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if (m_kind == PatternKind::Constant)
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{
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assertThrow(m_data, OptimizerException, "No match group and no constant value given.");
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return Literal{_location, LiteralKind::Number, YulString{util::formatNumber(*m_data)}, {}};
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}
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else if (m_kind == PatternKind::Operation)
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{
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vector<Expression> arguments;
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for (auto const& arg: m_arguments)
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arguments.emplace_back(arg.toExpression(_location));
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string name = instructionInfo(m_instruction).name;
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transform(begin(name), end(name), begin(name), [](auto _c) { return tolower(_c); });
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return FunctionCall{
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_location,
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Identifier{_location, YulString{name}},
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std::move(arguments)
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};
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}
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assertThrow(false, OptimizerException, "Pattern of kind 'any', but no match group.");
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}
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u256 Pattern::d() const
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{
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return valueOfNumberLiteral(std::get<Literal>(matchGroupValue()));
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}
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Expression const& Pattern::matchGroupValue() const
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{
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assertThrow(m_matchGroup > 0, OptimizerException, "");
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assertThrow(!!m_matchGroups, OptimizerException, "");
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assertThrow((*m_matchGroups)[m_matchGroup], OptimizerException, "");
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return *(*m_matchGroups)[m_matchGroup];
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}
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