path: root/libjulia/optimiser/SimplificationRules.cpp

/*
    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/>.
*/
/**
 * Module for applying replacement rules against Expressions.
 */

#include <libjulia/optimiser/SimplificationRules.h>

#include <libjulia/optimiser/Utilities.h>
#include <libjulia/optimiser/ASTCopier.h>

#include <libsolidity/inlineasm/AsmData.h>

#include <libevmasm/RuleList.h>

using namespace std;
using namespace dev;
using namespace dev::julia;


tuple<Pattern, function<Pattern()>, bool> const* SimplificationRules::findFirstMatch(Expression const& _expr)
{
    if (_expr.type() != typeid(FunctionalInstruction))
        return nullptr;

    static SimplificationRules rules;

    FunctionalInstruction const& instruction = boost::get<FunctionalInstruction const&>(_expr);
    for (auto const& rule: rules.m_rules[byte(instruction.instruction)])
    {
        rules.resetMatchGroups();
        if (std::get<0>(rule).matches(_expr))
            return &rule;
    }
    return nullptr;
}

void SimplificationRules::addRules(vector<tuple<Pattern, function<Pattern()>, bool>> const& _rules)
{
    for (auto const& r: _rules)
        addRule(r);
}

void SimplificationRules::addRule(tuple<Pattern, function<Pattern()>, bool> const& _rule)
{
    m_rules[byte(std::get<0>(_rule).instruction())].push_back(_rule);
}

SimplificationRules::SimplificationRules()
{
    // Multiple occurences 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 X;
    Pattern Y;
    A.setMatchGroup(1, m_matchGroups);
    B.setMatchGroup(2, m_matchGroups);
    C.setMatchGroup(3, m_matchGroups);
    X.setMatchGroup(4, m_matchGroups);
    Y.setMatchGroup(5, m_matchGroups);

    addRules(simplificationRuleList(A, B, C, X, Y));
}

Pattern::Pattern(solidity::Instruction _instruction, vector<Pattern> const& _arguments):
    m_kind(PatternKind::Operation),
    m_instruction(_instruction),
    m_arguments(_arguments)
{
}

void Pattern::setMatchGroup(unsigned _group, map<unsigned, Expression const*>& _matchGroups)
{
    m_matchGroup = _group;
    m_matchGroups = &_matchGroups;
}

bool Pattern::matches(Expression const& _expr) const
{
    if (m_kind == PatternKind::Constant)
    {
        if (_expr.type() != typeid(Literal))
            return false;
        Literal const& literal = boost::get<Literal const&>(_expr);
        if (literal.kind != assembly::LiteralKind::Number)
            return false;
        if (m_data && *m_data != u256(literal.value))
            return false;
        assertThrow(m_arguments.empty(), OptimizerException, "");
    }
    else if (m_kind == PatternKind::Operation)
    {
        if (_expr.type() != typeid(FunctionalInstruction))
            return false;
        FunctionalInstruction const& instr = boost::get<FunctionalInstruction const&>(_expr);
        if (m_instruction != instr.instruction)
            return false;
        assertThrow(m_arguments.size() == instr.arguments.size(), OptimizerException, "");
        for (size_t i = 0; i < m_arguments.size(); ++i)
            if (!m_arguments[i].matches(instr.arguments.at(i)))
                return false;
    }
    else
    {
        assertThrow(m_arguments.empty(), OptimizerException, "");
    }
    // We do not support matching multiple expressions that require the same value.
    if (m_matchGroup)
    {
        if (m_matchGroups->count(m_matchGroup))
            return false;
        (*m_matchGroups)[m_matchGroup] = &_expr;
    }
    return true;
}

solidity::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, assembly::LiteralKind::Number, m_data->str(), ""};
    }
    else if (m_kind == PatternKind::Operation)
    {
        vector<Expression> arguments;
        for (auto const& arg: m_arguments)
            arguments.emplace_back(arg.toExpression(_location));
        return FunctionalInstruction{_location, m_instruction, std::move(arguments)};
    }
    assertThrow(false, OptimizerException, "Pattern of kind 'any', but no match group.");
}

u256 Pattern::d() const
{
    Literal const& literal = boost::get<Literal const&>(matchGroupValue());
    assertThrow(literal.kind == assembly::LiteralKind::Number, OptimizerException, "");
    return u256(literal.value);
}

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];
}