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/*
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 <http://www.gnu.org/licenses/>.
*/
/**
* @file SimplificationRules
* @author Christian <chris@ethereum.org>
* @date 2017
* Module for applying replacement rules against Expressions.
*/
#pragma once
#include <libevmasm/ExpressionClasses.h>
#include <functional>
#include <vector>
namespace dev
{
namespace eth
{
class Pattern;
/**
* Container for all simplification rules.
*/
class Rules: public boost::noncopyable
{
public:
using Expression = ExpressionClasses::Expression;
Rules();
/// @returns a pointer to the first matching pattern and sets the match
/// groups accordingly.
std::tuple<Pattern, std::function<Pattern()>, bool> const* findFirstMatch(
Expression const& _expr,
ExpressionClasses const& _classes
);
private:
void addRules(std::vector<std::tuple<Pattern, std::function<Pattern()>, bool>> const& _rules);
void addRule(std::tuple<Pattern, std::function<Pattern()>, bool> const& _rule);
void resetMatchGroups() { m_matchGroups.clear(); }
std::map<unsigned, Expression const*> m_matchGroups;
/// Pattern to match, replacement to be applied and flag indicating whether
/// the replacement might remove some elements (except constants).
std::vector<std::tuple<Pattern, std::function<Pattern()>, bool>> m_rules[256];
};
/**
* Pattern to match against an expression.
* Also stores matched expressions to retrieve them later, for constructing new expressions using
* ExpressionTemplate.
*/
class Pattern
{
public:
using Expression = ExpressionClasses::Expression;
using Id = ExpressionClasses::Id;
// Matches a specific constant value.
Pattern(unsigned _value): Pattern(u256(_value)) {}
// Matches a specific constant value.
Pattern(u256 const& _value): m_type(Push), m_requireDataMatch(true), m_data(std::make_shared<u256>(_value)) {}
// Matches a specific assembly item type or anything if not given.
Pattern(AssemblyItemType _type = UndefinedItem): m_type(_type) {}
// Matches a given instruction with given arguments
Pattern(Instruction _instruction, std::vector<Pattern> const& _arguments = {});
/// Sets this pattern to be part of the match group with the identifier @a _group.
/// Inside one rule, all patterns in the same match group have to match expressions from the
/// same expression equivalence class.
void setMatchGroup(unsigned _group, std::map<unsigned, Expression const*>& _matchGroups);
unsigned matchGroup() const { return m_matchGroup; }
bool matches(Expression const& _expr, ExpressionClasses const& _classes) const;
AssemblyItem toAssemblyItem(SourceLocation const& _location) const;
std::vector<Pattern> arguments() const { return m_arguments; }
/// @returns the id of the matched expression if this pattern is part of a match group.
Id id() const { return matchGroupValue().id; }
/// @returns the data of the matched expression if this pattern is part of a match group.
u256 const& d() const { return matchGroupValue().item->data(); }
std::string toString() const;
AssemblyItemType type() const { return m_type; }
Instruction instruction() const
{
assertThrow(type() == Operation, OptimizerException, "");
return m_instruction;
}
private:
bool matchesBaseItem(AssemblyItem const* _item) const;
Expression const& matchGroupValue() const;
u256 const& data() const;
AssemblyItemType m_type;
bool m_requireDataMatch = false;
Instruction m_instruction; ///< Only valid if m_type is Operation
std::shared_ptr<u256> m_data; ///< Only valid if m_type is not Operation
std::vector<Pattern> m_arguments;
unsigned m_matchGroup = 0;
std::map<unsigned, Expression const*>* m_matchGroups = nullptr;
};
/**
* Template for a new expression that can be built from matched patterns.
*/
struct ExpressionTemplate
{
using Expression = ExpressionClasses::Expression;
using Id = ExpressionClasses::Id;
explicit ExpressionTemplate(Pattern const& _pattern, SourceLocation const& _location);
std::string toString() const;
bool hasId = false;
/// Id of the matched expression, if available.
Id id = Id(-1);
// Otherwise, assembly item.
AssemblyItem item = UndefinedItem;
std::vector<ExpressionTemplate> arguments;
};
}
}
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