path: root/libevmasm/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 <fstream>
#include <libevmasm/CommonSubexpressionEliminator.h>
#include <libevmasm/ControlFlowGraph.h>
#include <libevmasm/BlockDeduplicator.h>
#include <libevmasm/ConstantOptimiser.h>
#include <libevmasm/GasMeter.h>
#include <json/json.h>
using namespace std;
using namespace dev;
using namespace dev::eth;

void Assembly::append(Assembly const& _a)
{
    auto newDeposit = m_deposit + _a.deposit();
    for (AssemblyItem i: _a.m_items)
    {
        if (i.type() == Tag || i.type() == PushTag)
            i.setData(i.data() + m_usedTags);
        else if (i.type() == PushSub || i.type() == PushSubSize)
            i.setData(i.data() + m_subs.size());
        append(i);
    }
    m_deposit = newDeposit;
    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);
    m_subs += _a.m_subs;
    for (auto const& lib: _a.m_libraries)
        m_libraries.insert(lib);

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

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

string Assembly::out() const
{
    stringstream ret;
    stream(ret);
    return ret.str();
}

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)
            ret += i.bytesRequired(br);
        if (dev::bytesRequired(ret) <= br)
            return ret;
    }
}

string Assembly::locationFromSources(StringMap const& _sourceCodes, SourceLocation const& _location) const
{
    if (_location.isEmpty() || _sourceCodes.empty() || _location.start >= _location.end || _location.start < 0)
        return "";

    auto it = _sourceCodes.find(*_location.sourceName);
    if (it == _sourceCodes.end())
        return "";

    string const& source = it->second;
    if (size_t(_location.start) >= source.size())
        return "";

    string cut = source.substr(_location.start, _location.end - _location.start);
    auto newLinePos = cut.find_first_of("\n");
    if (newLinePos != string::npos)
        cut = cut.substr(0, newLinePos) + "...";

    return cut;
}

ostream& Assembly::streamAsm(ostream& _out, string const& _prefix, StringMap const& _sourceCodes) const
{
    _out << _prefix << ".code:" << endl;
    for (AssemblyItem const& i: m_items)
    {
        _out << _prefix;
        switch (i.type())
        {
        case Operation:
            _out << "  " << instructionInfo(i.instruction()).name  << "\t" << i.getJumpTypeAsString();
            break;
        case Push:
            _out << "  PUSH" << dec << max<unsigned>(1, dev::bytesRequired(i.data())) << " 0x" << hex << i.data();
            break;
        case PushString:
            _out << "  PUSH \"" << m_strings.at((h256)i.data()) << "\"";
            break;
        case PushTag:
            if (i.data() == 0)
                _out << "  PUSH [ErrorTag]";
            else
                _out << "  PUSH [tag" << dec << i.data() << "]";
            break;
        case PushSub:
            _out << "  PUSH [$" << h256(i.data()).abridgedMiddle() << "]";
            break;
        case PushSubSize:
            _out << "  PUSH #[$" << h256(i.data()).abridgedMiddle() << "]";
            break;
        case PushProgramSize:
            _out << "  PUSHSIZE";
            break;
        case PushLibraryAddress:
            _out << "  PUSHLIB \"" << m_libraries.at(h256(i.data())) << "\"";
            break;
        case Tag:
            _out << "tag" << dec << i.data() << ": " << endl << _prefix << "  JUMPDEST";
            break;
        case PushData:
            _out << "  PUSH [" << hex << (unsigned)i.data() << "]";
            break;
        default:
            BOOST_THROW_EXCEPTION(InvalidOpcode());
        }
        _out << "\t\t" << locationFromSources(_sourceCodes, i.location()) << endl;
    }

    if (!m_data.empty() || !m_subs.empty())
    {
        _out << _prefix << ".data:" << endl;
        for (auto const& i: m_data)
            if (u256(i.first) >= m_subs.size())
                _out << _prefix << "  " << hex << (unsigned)(u256)i.first << ": " << dev::toHex(i.second) << endl;
        for (size_t i = 0; i < m_subs.size(); ++i)
        {
            _out << _prefix << "  " << hex << i << ": " << endl;
            m_subs[i].stream(_out, _prefix + "  ", _sourceCodes);
        }
    }
    return _out;
}

Json::Value Assembly::createJsonValue(string _name, int _begin, int _end, string _value, string _jumpType) const
{
    Json::Value value;
    value["name"] = _name;
    value["begin"] = _begin;
    value["end"] = _end;
    if (!_value.empty())
        value["value"] = _value;
    if (!_jumpType.empty())
        value["jumpType"] = _jumpType;
    return value;
}

string toStringInHex(u256 _value)
{
    std::stringstream hexStr;
    hexStr << hex << _value;
    return hexStr.str();
}

Json::Value Assembly::streamAsmJson(ostream& _out, StringMap const& _sourceCodes) const
{
    Json::Value root;

    Json::Value collection(Json::arrayValue);
    for (AssemblyItem const& i: m_items)
    {
        switch (i.type())
        {
        case Operation:
            collection.append(
                createJsonValue(instructionInfo(i.instruction()).name, i.location().start, i.location().end, i.getJumpTypeAsString()));
            break;
        case Push:
            collection.append(
                createJsonValue("PUSH", i.location().start, i.location().end, toStringInHex(i.data()), i.getJumpTypeAsString()));
            break;
        case PushString:
            collection.append(
                createJsonValue("PUSH tag", i.location().start, i.location().end, m_strings.at((h256)i.data())));
            break;
        case PushTag:
            if (i.data() == 0)
                collection.append(
                    createJsonValue("PUSH [ErrorTag]", i.location().start, i.location().end, ""));
            else
                collection.append(
                    createJsonValue("PUSH [tag]", i.location().start, i.location().end, string(i.data())));
            break;
        case PushSub:
            collection.append(
                createJsonValue("PUSH [$]", i.location().start, i.location().end, dev::toString(h256(i.data()))));
            break;
        case PushSubSize:
            collection.append(
                createJsonValue("PUSH #[$]", i.location().start, i.location().end, dev::toString(h256(i.data()))));
            break;
        case PushProgramSize:
            collection.append(
                createJsonValue("PUSHSIZE", i.location().start, i.location().end));
            break;
        case PushLibraryAddress:
            collection.append(
                createJsonValue("PUSHLIB", i.location().start, i.location().end, m_libraries.at(h256(i.data())))
            );
            break;
        case Tag:
            collection.append(
                createJsonValue("tag", i.location().start, i.location().end, string(i.data())));
            collection.append(
                createJsonValue("JUMPDEST", i.location().start, i.location().end));
            break;
        case PushData:
            collection.append(createJsonValue("PUSH data", i.location().start, i.location().end, toStringInHex(i.data())));
            break;
        default:
            BOOST_THROW_EXCEPTION(InvalidOpcode());
        }
    }

    root[".code"] = collection;

    if (!m_data.empty() || !m_subs.empty())
    {
        Json::Value data;
        for (auto const& i: m_data)
            if (u256(i.first) >= m_subs.size())
                data[toStringInHex((u256)i.first)] = toHex(i.second);

        for (size_t i = 0; i < m_subs.size(); ++i)
        {
            std::stringstream hexStr;
            hexStr << hex << i;
            data[hexStr.str()] = m_subs[i].stream(_out, "", _sourceCodes, true);
        }
        root[".data"] = data;
        _out << root;
    }
    return root;
}

Json::Value Assembly::stream(ostream& _out, string const& _prefix, StringMap const& _sourceCodes, bool _inJsonFormat) const
{
    if (_inJsonFormat)
        return streamAsmJson(_out, _sourceCodes);
    else
    {
        streamAsm(_out, _prefix, _sourceCodes);
        return Json::Value();
    }
}

AssemblyItem const& Assembly::append(AssemblyItem const& _i)
{
    m_deposit += _i.deposit();
    m_items.push_back(_i);
    if (m_items.back().location().isEmpty() && !m_currentSourceLocation.isEmpty())
        m_items.back().setLocation(m_currentSourceLocation);
    return back();
}

AssemblyItem Assembly::newPushLibraryAddress(string const& _identifier)
{
    h256 h(dev::keccak256(_identifier));
    m_libraries[h] = _identifier;
    return AssemblyItem(PushLibraryAddress, h);
}

void Assembly::injectStart(AssemblyItem const& _i)
{
    m_items.insert(m_items.begin(), _i);
}

Assembly& Assembly::optimise(bool _enable, bool _isCreation, size_t _runs)
{
    if (!_enable)
        return *this;

    unsigned total = 0;
    for (unsigned count = 1; count > 0; total += count)
    {
        count = 0;

        // This only modifies PushTags, we have to run again to actually remove code.
        BlockDeduplicator dedup(m_items);
        if (dedup.deduplicate())
            count++;

        {
            // Control flow graph that resets knowledge at path joins.
            ControlFlowGraph cfg(m_items, false);
            AssemblyItems optimisedItems;
            for (BasicBlock const& block: cfg.optimisedBlocks())
            {
                // We used to start with the block's initial state but it caused
                // too many inconsistencies.
                KnownState emptyState;
                CommonSubexpressionEliminator eliminator(emptyState);
                auto iter = m_items.begin() + block.begin;
                auto const end = m_items.begin() + block.end;
                while (iter < end)
                {
                    auto orig = iter;
                    iter = eliminator.feedItems(iter, end);
                    bool shouldReplace = false;
                    AssemblyItems optimisedChunk;
                    try
                    {
                        optimisedChunk = eliminator.getOptimizedItems();
                        shouldReplace = (optimisedChunk.size() < size_t(iter - orig));
                    }
                    catch (StackTooDeepException const&)
                    {
                        // This might happen if the opcode reconstruction is not as efficient
                        // as the hand-crafted code.
                    }
                    catch (ItemNotAvailableException const&)
                    {
                        // This might happen if e.g. associativity and commutativity rules
                        // reorganise the expression tree, but not all leaves are available.
                    }

                    if (shouldReplace)
                    {
                        count++;
                        optimisedItems += optimisedChunk;
                    }
                    else
                        copy(orig, iter, back_inserter(optimisedItems));
                }
            }

            if (optimisedItems.size() < m_items.size())
            {
                m_items = move(optimisedItems);
                count++;
            }
        }
    }

    total += ConstantOptimisationMethod::optimiseConstants(
        _isCreation,
        _isCreation ? 1 : _runs,
        *this,
        m_items
    );

    for (auto& sub: m_subs)
      sub.optimise(true, false, _runs);

    return *this;
}

LinkerObject const& Assembly::assemble() const
{
    if (!m_assembledObject.bytecode.empty())
        return m_assembledObject;

    LinkerObject& ret = m_assembledObject;

    unsigned totalBytes = bytesRequired();
    vector<unsigned> tagPos(m_usedTags);
    map<unsigned, unsigned> tagRef;
    multimap<h256, unsigned> dataRef;
    multimap<size_t, size_t> subRef;
    vector<unsigned> sizeRef; ///< Pointers to code locations where the size of the program is inserted
    unsigned bytesPerTag = dev::bytesRequired(totalBytes);
    byte tagPush = (byte)Instruction::PUSH1 - 1 + bytesPerTag;

    unsigned bytesRequiredIncludingData = bytesRequired();
    for (auto const& sub: m_subs)
        bytesRequiredIncludingData += sub.assemble().bytecode.size();

    unsigned bytesPerDataRef = dev::bytesRequired(bytesRequiredIncludingData);
    byte dataRefPush = (byte)Instruction::PUSH1 - 1 + bytesPerDataRef;
    ret.bytecode.reserve(bytesRequiredIncludingData);

    for (AssemblyItem const& i: m_items)
    {
        // store position of the invalid jump destination
        if (i.type() != Tag && tagPos[0] == 0)
            tagPos[0] = ret.bytecode.size();

        switch (i.type())
        {
        case Operation:
            ret.bytecode.push_back((byte)i.data());
            break;
        case PushString:
        {
            ret.bytecode.push_back((byte)Instruction::PUSH32);
            unsigned ii = 0;
            for (auto j: m_strings.at((h256)i.data()))
                if (++ii > 32)
                    break;
                else
                    ret.bytecode.push_back((byte)j);
            while (ii++ < 32)
                ret.bytecode.push_back(0);
            break;
        }
        case Push:
        {
            byte b = max<unsigned>(1, dev::bytesRequired(i.data()));
            ret.bytecode.push_back((byte)Instruction::PUSH1 - 1 + b);
            ret.bytecode.resize(ret.bytecode.size() + b);
            bytesRef byr(&ret.bytecode.back() + 1 - b, b);
            toBigEndian(i.data(), byr);
            break;
        }
        case PushTag:
        {
            ret.bytecode.push_back(tagPush);
            tagRef[ret.bytecode.size()] = (unsigned)i.data();
            ret.bytecode.resize(ret.bytecode.size() + bytesPerTag);
            break;
        }
        case PushData:
            ret.bytecode.push_back(dataRefPush);
            dataRef.insert(make_pair((h256)i.data(), ret.bytecode.size()));
            ret.bytecode.resize(ret.bytecode.size() + bytesPerDataRef);
            break;
        case PushSub:
            ret.bytecode.push_back(dataRefPush);
            subRef.insert(make_pair(size_t(i.data()), ret.bytecode.size()));
            ret.bytecode.resize(ret.bytecode.size() + bytesPerDataRef);
            break;
        case PushSubSize:
        {
            auto s = m_subs.at(size_t(i.data())).assemble().bytecode.size();
            i.setPushedValue(u256(s));
            byte b = max<unsigned>(1, dev::bytesRequired(s));
            ret.bytecode.push_back((byte)Instruction::PUSH1 - 1 + b);
            ret.bytecode.resize(ret.bytecode.size() + b);
            bytesRef byr(&ret.bytecode.back() + 1 - b, b);
            toBigEndian(s, byr);
            break;
        }
        case PushProgramSize:
        {
            ret.bytecode.push_back(dataRefPush);
            sizeRef.push_back(ret.bytecode.size());
            ret.bytecode.resize(ret.bytecode.size() + bytesPerDataRef);
            break;
        }
        case PushLibraryAddress:
            ret.bytecode.push_back(byte(Instruction::PUSH20));
            ret.linkReferences[ret.bytecode.size()] = m_libraries.at(i.data());
            ret.bytecode.resize(ret.bytecode.size() + 20);
            break;
        case Tag:
            tagPos[(unsigned)i.data()] = ret.bytecode.size();
            assertThrow(ret.bytecode.size() < 0xffffffffL, AssemblyException, "Tag too large.");
            assertThrow(i.data() != 0, AssemblyException, "");
            ret.bytecode.push_back((byte)Instruction::JUMPDEST);
            break;
        default:
            BOOST_THROW_EXCEPTION(InvalidOpcode());
        }
    }
    for (auto const& i: tagRef)
    {
        bytesRef r(ret.bytecode.data() + i.first, bytesPerTag);
        auto tag = i.second;
        if (tag >= tagPos.size())
            tag = 0;
        if (tag == 0)
            assertThrow(tagPos[tag] != 0, AssemblyException, "");

        toBigEndian(tagPos[tag], r);
    }

    if (!dataRef.empty() && !subRef.empty())
        ret.bytecode.push_back(0);
    for (size_t i = 0; i < m_subs.size(); ++i)
    {
        auto references = subRef.equal_range(i);
        if (references.first == references.second)
            continue;
        for (auto ref = references.first; ref != references.second; ++ref)
        {
            bytesRef r(ret.bytecode.data() + ref->second, bytesPerDataRef);
            toBigEndian(ret.bytecode.size(), r);
        }
        ret.append(m_subs[i].assemble());
    }
    for (auto const& dataItem: m_data)
    {
        auto references = dataRef.equal_range(dataItem.first);
        if (references.first == references.second)
            continue;
        for (auto ref = references.first; ref != references.second; ++ref)
        {
            bytesRef r(ret.bytecode.data() + ref->second, bytesPerDataRef);
            toBigEndian(ret.bytecode.size(), r);
        }
        ret.bytecode += dataItem.second;
    }
    for (unsigned pos: sizeRef)
    {
        bytesRef r(ret.bytecode.data() + pos, bytesPerDataRef);
        toBigEndian(ret.bytecode.size(), r);
    }
    return ret;
}