path: root/Assembly.cpp

/*
    This file is part of cpp-ethereum.

    cpp-ethereum 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.

    cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file Assembly.cpp
 * @author Gav Wood <i@gavwood.com>
 * @date 2014
 */

#include "Assembly.h"

#include <libethsupport/Log.h>
#include <libethcore/CommonEth.h>

using namespace std;
using namespace eth;

int AssemblyItem::deposit() const
{
    switch (m_type)
    {
    case Operation:
        return c_instructionInfo.at((Instruction)(byte)m_data).ret - c_instructionInfo.at((Instruction)(byte)m_data).args;
    case Push: case PushString: case PushTag: case PushData:
        return 1;
    case Tag:
        return 0;
    default:;
    }
    assert(false);
}

unsigned Assembly::bytesRequired() const
{
    for (unsigned br = 1;; ++br)
    {
        unsigned ret = 1;
        for (auto const& i: m_data)
            ret += i.second.size();

        for (AssemblyItem const& i: m_items)
            switch (i.m_type)
            {
            case Operation:
                ret++;
                break;
            case PushString:
                ret += 33;
                break;
            case Push:
                ret += 1 + max<unsigned>(1, eth::bytesRequired(i.m_data));
                break;
            case PushTag:
            case PushData:
                ret += 1 + br;
            case Tag:;
            default:;
            }
        if (eth::bytesRequired(ret) <= br)
            return ret;
    }
}

void Assembly::append(Assembly const& _a)
{
    for (AssemblyItem i: _a.m_items)
    {
        if (i.type() == Tag || i.type() == PushTag)
            i.m_data += m_usedTags;
        append(i);
    }
    m_usedTags += _a.m_usedTags;
    for (auto const& i: _a.m_data)
        m_data.insert(i);
    for (auto const& i: _a.m_strings)
        m_strings.insert(i);

    assert(!_a.m_baseDeposit);
    assert(!_a.m_totalDeposit);
}

void Assembly::append(Assembly const& _a, int _deposit)
{
    if (_deposit > _a.m_deposit)
        throw InvalidDeposit();
    else
    {
        append(_a);
        while (_deposit++ < _a.m_deposit)
            append(Instruction::POP);
    }
}

ostream& eth::operator<<(ostream& _out, AssemblyItemsConstRef _i)
{
    for (AssemblyItem const& i: _i)
        switch (i.type())
        {
        case Operation:
            _out << " " << c_instructionInfo.at((Instruction)(byte)i.data()).name;
            break;
        case Push:
            _out << " PUSH" << i.data();
            break;
        case PushString:
            _out << " PUSH'[" << h256(i.data()).abridged() << "]";
            break;
        case PushTag:
            _out << " PUSH[tag" << i.data() << "]";
            break;
        case Tag:
            _out << " tag" << i.data() << ":";
            break;
        case PushData:
            _out << " PUSH*[" << h256(i.data()).abridged() << "]";
            break;
        case UndefinedItem:
            _out << " ???";
        default:;
        }
    return _out;
}

ostream& Assembly::streamOut(ostream& _out) const
{
    _out << ".code:" << endl;
    for (AssemblyItem const& i: m_items)
        switch (i.m_type)
        {
        case Operation:
            _out << "  " << c_instructionInfo.at((Instruction)(byte)i.m_data).name << endl;
            break;
        case Push:
            _out << "  PUSH " << i.m_data << endl;
            break;
        case PushString:
            _out << "  PUSH \"" << m_strings.at((h256)i.m_data) << "\"" << endl;
            break;
        case PushTag:
            _out << "  PUSH [tag" << i.m_data << "]" << endl;
            break;
        case Tag:
            _out << "tag" << i.m_data << ": " << endl;
            break;
        case PushData:
            _out << "  PUSH [" << h256(i.m_data).abridged() << "]" << endl;
            break;
        default:;
        }

    if (m_data.size())
    {
        _out << ".data:" << endl;
        for (auto const& i: m_data)
            _out << "  " << i.first.abridged() << ": " << toHex(i.second) << endl;
    }
    return _out;
}

AssemblyItem const& Assembly::append(AssemblyItem const& _i)
{
    m_deposit += _i.deposit();
    m_items.push_back(_i);
    return back();
}

inline bool matches(AssemblyItemsConstRef _a, AssemblyItemsConstRef _b)
{
    if (_a.size() != _b.size())
        return false;
    for (unsigned i = 0; i < _a.size(); ++i)
        if (!_a[i].match(_b[i]))
            return false;
    return true;
}

struct OptimiserChannel: public LogChannel { static const char* name() { return "OPT"; } static const int verbosity = 12; };
#define copt eth::LogOutputStream<OptimiserChannel, true>()

void Assembly::optimise()
{
    map<Instruction, function<u256(u256, u256)>> c_simple =
    {
        { Instruction::SUB, [](u256 a, u256 b)->u256{return a - b;} },
        { Instruction::DIV, [](u256 a, u256 b)->u256{return a / b;} },
        { Instruction::SDIV, [](u256 a, u256 b)->u256{u256 r; (s256&)r = (s256&)a / (s256&)b; return r;} },
        { Instruction::MOD, [](u256 a, u256 b)->u256{return a % b;} },
        { Instruction::SMOD, [](u256 a, u256 b)->u256{u256 r; (s256&)r = (s256&)a % (s256&)b; return r;} },
        { Instruction::EXP, [](u256 a, u256 b)->u256{return boost::multiprecision::pow(a, (unsigned)b);} },
        { Instruction::LT, [](u256 a, u256 b)->u256{return a < b ? 1 : 0;} },
        { Instruction::GT, [](u256 a, u256 b)->u256{return a > b ? 1 : 0;} },
        { Instruction::SLT, [](u256 a, u256 b)->u256{return *(s256*)&a < *(s256*)&b ? 1 : 0;} },
        { Instruction::SGT, [](u256 a, u256 b)->u256{return *(s256*)&a > *(s256*)&b ? 1 : 0;} },
        { Instruction::EQ, [](u256 a, u256 b)->u256{return a == b ? 1 : 0;} },
    };
    map<Instruction, function<u256(u256, u256)>> c_associative =
    {
        { Instruction::ADD, [](u256 a, u256 b)->u256{return a + b;} },
        { Instruction::MUL, [](u256 a, u256 b)->u256{return a * b;} },
    };
    std::vector<pair<AssemblyItems, function<AssemblyItems(AssemblyItemsConstRef)>>> rules =
    {
        { { Push, Instruction::POP }, [](AssemblyItemsConstRef) -> AssemblyItems { return {}; } },
        { { Push, PushTag, Instruction::JUMPI }, [](AssemblyItemsConstRef m) -> AssemblyItems { if (m[0].data()) return { m[1], Instruction::JUMP }; else return {}; } },
    };

    for (auto const& i: c_simple)
        rules.push_back({ { Push, Push, i.first }, [&](AssemblyItemsConstRef m) -> AssemblyItems { return { i.second(m[1].data(), m[0].data()) }; } });
    for (auto const& i: c_associative)
    {
        rules.push_back({ { Push, Push, i.first }, [&](AssemblyItemsConstRef m) -> AssemblyItems { return { i.second(m[1].data(), m[0].data()) }; } });
        rules.push_back({ { Push, i.first, Push, i.first }, [&](AssemblyItemsConstRef m) -> AssemblyItems { return { i.second(m[2].data(), m[0].data()), i.first }; } });
        rules.push_back({ { PushTag, Instruction::JUMP, Tag }, [&](AssemblyItemsConstRef m) -> AssemblyItems { if (m[0].m_data == m[2].m_data) return {}; else return m.toVector(); }});
    }

    copt << *this;

    unsigned total = 0;
    for (unsigned count = 1; count > 0; total += count)
    {
        count = 0;
        map<u256, unsigned> tags;
        for (unsigned i = 0; i < m_items.size(); ++i)
        {
            for (auto const& r: rules)
            {
                auto vr = AssemblyItemsConstRef(&m_items).cropped(i, r.first.size());
                if (matches(&r.first, vr))
                {
                    auto rw = r.second(vr);
                    if (rw.size() < vr.size())
                    {
                        copt << vr << "matches" << AssemblyItemsConstRef(&r.first) << "becomes...";
                        for (unsigned j = 0; j < vr.size(); ++j)
                            if (j < rw.size())
                                m_items[i + j] = rw[j];
                            else
                                m_items.erase(m_items.begin() + i + rw.size());
                        copt << AssemblyItemsConstRef(&rw);
                        count++;
                        copt << "Now:\n" << m_items;
                    }
                }
            }
            if (m_items[i].type() == Operation && m_items[i].data() == (byte)Instruction::JUMP)
            {
                bool o = false;
                while (m_items.size() > i + 1 && m_items[i + 1].type() != Tag)
                {
                    m_items.erase(m_items.begin() + i + 1);
                    o = true;
                }
                if (o)
                {
                    copt << "Jump with no tag. Now:\n" << m_items;
                    ++count;
                }
            }
        }

        for (unsigned i = 0; i < m_items.size(); ++i)
            if (m_items[i].type() == Tag)
                tags.insert(make_pair(m_items[i].data(), i));

        for (auto const& i: m_items)
            if (i.type() == PushTag)
                tags.erase(i.data());

        if (tags.size())
        {
            auto t = *tags.begin();
            unsigned i = t.second;
            if (i && m_items[i - 1].type() == Operation && m_items[i - 1].data() == (byte)Instruction::JUMP)
                while (i < m_items.size() && (m_items[i].type() != Tag || tags.count(m_items[i].data())))
                {
                    if (m_items[i].type() == Tag && tags.count(m_items[i].data()))
                        tags.erase(m_items[i].data());
                    m_items.erase(m_items.begin() + i);
                }
            else
            {
                m_items.erase(m_items.begin() + i);
                tags.erase(t.first);
            }
            copt << "Unused tag. Now:\n" << m_items;
            ++count;
        }
    }

    copt << total << " optimisations done.";
}

bytes Assembly::assemble() const
{
    bytes ret;

    unsigned totalBytes = bytesRequired();
    ret.reserve(totalBytes);
    vector<unsigned> tagPos(m_usedTags);
    map<unsigned, unsigned> tagRef;
    multimap<h256, unsigned> dataRef;
    unsigned bytesPerTag = eth::bytesRequired(totalBytes);
    byte tagPush = (byte)Instruction::PUSH1 - 1 + bytesPerTag;

    for (AssemblyItem const& i: m_items)
        switch (i.m_type)
        {
        case Operation:
            ret.push_back((byte)i.m_data);
            break;
        case PushString:
        {
            ret.push_back((byte)Instruction::PUSH32);
            unsigned ii = 0;
            for (auto j: m_strings.at((h256)i.m_data))
                if (++ii > 32)
                    break;
                else
                    ret.push_back((byte)j);
            while (ii++ < 32)
                ret.push_back(0);
            break;
        }
        case Push:
        {
            byte b = max<unsigned>(1, eth::bytesRequired(i.m_data));
            ret.push_back((byte)Instruction::PUSH1 - 1 + b);
            ret.resize(ret.size() + b);
            bytesRef byr(&ret.back() + 1 - b, b);
            toBigEndian(i.m_data, byr);
            break;
        }
        case PushTag:
        {
            ret.push_back(tagPush);
            tagRef[ret.size()] = (unsigned)i.m_data;
            ret.resize(ret.size() + bytesPerTag);
            break;
        }
        case PushData:
        {
            ret.push_back(tagPush);
            dataRef.insert(make_pair((h256)i.m_data, ret.size()));
            ret.resize(ret.size() + bytesPerTag);
            break;
        }
        case Tag:
            tagPos[(unsigned)i.m_data] = ret.size();
            break;
        default:;
        }

    for (auto const& i: tagRef)
    {
        bytesRef r(ret.data() + i.first, bytesPerTag);
        toBigEndian(tagPos[i.second], r);
    }

    if (m_data.size())
    {
        ret.push_back(0);
        for (auto const& i: m_data)
        {
            auto its = dataRef.equal_range(i.first);
            if (its.first != its.second)
            {
                for (auto it = its.first; it != its.second; ++it)
                {
                    bytesRef r(ret.data() + it->second, bytesPerTag);
                    toBigEndian(ret.size(), r);
                }
                for (auto b: i.second)
                    ret.push_back(b);
            }
        }
    }
    return ret;
}