IRCompiler.cpp

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#include <Ark/Compiler/IntermediateRepresentation/IRCompiler.hpp>
 
#include <chrono>
#include <utility>
#include <optional>
#include <unordered_map>
#include <Proxy/Picosha2.hpp>
#include <fmt/ostream.h>
 
#include <Ark/Constants.hpp>
#include <Ark/Literals.hpp>
#include <Ark/Compiler/IntermediateRepresentation/InstLoc.hpp>
#include <Ark/Compiler/Serialization/IntegerSerializer.hpp>
#include <Ark/Compiler/Serialization/IEEE754Serializer.hpp>
 
namespace Ark::internal
{
    using namespace literals;
 
    IRCompiler::IRCompiler(const unsigned debug) :
        m_logger("IRCompiler", debug)
    {}
 
    void IRCompiler::process(const std::vector<IR::Block>& pages, const std::vector<std::string>& symbols, const std::vector<ValTableElem>& values)
    {
        m_logger.traceStart("process");
        pushFileHeader();
        pushSymbolTable(symbols);
        pushValueTable(values);
 
        // compute a list of unique filenames
        for (const auto& page : pages)
        {
            for (const auto& inst : page)
            {
                if (std::ranges::find(m_filenames, inst.filename()) == m_filenames.end() && inst.hasValidSourceLocation())
                    m_filenames.push_back(inst.filename());
            }
        }
 
        pushFilenameTable();
        pushInstLocTable(pages);
 
        m_ir = pages;
        compile();
 
        if (m_ir.empty())
        {
            // code segment with a single instruction
            m_bytecode.push_back(CODE_SEGMENT_START);
            m_bytecode.push_back(0_u8);
            m_bytecode.push_back(1_u8);
 
            m_bytecode.push_back(0_u8);
            m_bytecode.push_back(HALT);
            m_bytecode.push_back(0_u8);
            m_bytecode.push_back(0_u8);
        }
 
        // generate a hash of the tables + bytecode
        std::vector<unsigned char> hash_out(picosha2::k_digest_size);
        picosha2::hash256(m_bytecode.begin() + bytecode::HeaderSize, m_bytecode.end(), hash_out);
        m_bytecode.insert(m_bytecode.begin() + bytecode::HeaderSize, hash_out.begin(), hash_out.end());
 
        m_logger.traceEnd();
    }
 
    void IRCompiler::dumpToStream(std::ostream& stream) const
    {
        std::size_t index = 0;
        for (const auto& block : m_ir)
        {
            fmt::println(stream, "page_{}", index);
            for (const auto& entity : block)
            {
                switch (entity.kind())
                {
                    case IR::Kind::Label:
                        fmt::println(stream, ".L{}:", entity.label());
                        break;
 
                    case IR::Kind::Goto:
                        fmt::println(stream, "\tGOTO L{}", entity.label());
                        break;
 
                    case IR::Kind::GotoIfTrue:
                        fmt::println(stream, "\tGOTO_IF_TRUE L{}", entity.label());
                        break;
 
                    case IR::Kind::GotoIfFalse:
                        fmt::println(stream, "\tGOTO_IF_FALSE L{}", entity.label());
                        break;
 
                    case IR::Kind::Opcode:
                        fmt::println(stream, "\t{} {}", InstructionNames[entity.inst()], entity.primaryArg());
                        break;
 
                    case IR::Kind::Opcode2Args:
                        fmt::println(stream, "\t{} {}, {}", InstructionNames[entity.inst()], entity.primaryArg(), entity.secondaryArg());
                        break;
                }
            }
 
            fmt::println(stream, "");
            ++index;
        }
    }
 
    const bytecode_t& IRCompiler::bytecode() const noexcept
    {
        return m_bytecode;
    }
 
    void IRCompiler::compile()
    {
        // push the different code segments
        for (std::size_t i = 0, end = m_ir.size(); i < end; ++i)
        {
            IR::Block& page = m_ir[i];
            // just in case we got too far, always add a HALT to be sure the
            // VM won't do anything crazy
            page.emplace_back(HALT);
 
            // push number of elements
            const auto page_size = std::ranges::count_if(page, [](const auto& a) {
                return a.kind() != IR::Kind::Label;
            });
            if (std::cmp_greater(page_size, std::numeric_limits<uint16_t>::max()))
                throw std::overflow_error(fmt::format("Size of page {} exceeds the maximum size of 2^16 - 1", i));
 
            m_bytecode.push_back(CODE_SEGMENT_START);
            serializeOn2BytesToVecBE(page_size, m_bytecode);
 
            // register labels position
            uint16_t pos = 0;
            std::unordered_map<IR::label_t, uint16_t> label_to_position;
            for (auto& inst : page)
            {
                switch (inst.kind())
                {
                    case IR::Kind::Label:
                        label_to_position[inst.label()] = pos;
                        break;
 
                    default:
                        ++pos;
                }
            }
 
            for (auto& inst : page)
            {
                switch (inst.kind())
                {
                    case IR::Kind::Goto:
                        pushWord(Word(JUMP, label_to_position[inst.label()]));
                        break;
 
                    case IR::Kind::GotoIfTrue:
                        pushWord(Word(POP_JUMP_IF_TRUE, label_to_position[inst.label()]));
                        break;
 
                    case IR::Kind::GotoIfFalse:
                        pushWord(Word(POP_JUMP_IF_FALSE, label_to_position[inst.label()]));
                        break;
 
                    case IR::Kind::Opcode:
                        [[fallthrough]];
                    case IR::Kind::Opcode2Args:
                        pushWord(inst.bytecode());
                        break;
 
                    default:
                        break;
                }
            }
        }
    }
 
    void IRCompiler::pushWord(const Word& word)
    {
        m_bytecode.push_back(word.opcode);
        m_bytecode.push_back(word.byte_1);
        m_bytecode.push_back(word.byte_2);
        m_bytecode.push_back(word.byte_3);
    }
 
    void IRCompiler::pushFileHeader() noexcept
    {
        /*
            Generating headers:
                - lang name (to be sure we are executing an ArkScript file)
                    on 4 bytes (ark + padding)
                - version (major: 2 bytes, minor: 2 bytes, patch: 2 bytes)
                - timestamp (8 bytes, unix format)
        */
 
        m_bytecode.push_back('a');
        m_bytecode.push_back('r');
        m_bytecode.push_back('k');
        m_bytecode.push_back(0_u8);
 
        // push version
        for (const int n : std::array { ARK_VERSION_MAJOR, ARK_VERSION_MINOR, ARK_VERSION_PATCH })
            serializeOn2BytesToVecBE(n, m_bytecode);
 
        // push timestamp
        const long long timestamp = std::chrono::duration_cast<std::chrono::seconds>(
                                        std::chrono::system_clock::now().time_since_epoch())
                                        .count();
        for (long i = 0; i < 8; ++i)
        {
            const long shift = 8 * (7 - i);
            const auto ts_byte = static_cast<uint8_t>((timestamp & (0xffLL << shift)) >> shift);
            m_bytecode.push_back(ts_byte);
        }
    }
 
    void IRCompiler::pushSymbolTable(const std::vector<std::string>& symbols)
    {
        const std::size_t symbol_size = symbols.size();
        if (symbol_size > std::numeric_limits<uint16_t>::max())
            throw std::overflow_error(fmt::format("Too many symbols: {}, exceeds the maximum size of 2^16 - 1", symbol_size));
 
        m_bytecode.push_back(SYM_TABLE_START);
        serializeOn2BytesToVecBE(symbol_size, m_bytecode);
 
        for (const auto& sym : symbols)
        {
            // push the string, null terminated
            std::ranges::transform(sym, std::back_inserter(m_bytecode), [](const char i) {
                return static_cast<uint8_t>(i);
            });
            m_bytecode.push_back(0_u8);
        }
    }
 
    void IRCompiler::pushValueTable(const std::vector<ValTableElem>& values)
    {
        const std::size_t value_size = values.size();
        if (value_size > std::numeric_limits<uint16_t>::max())
            throw std::overflow_error(fmt::format("Too many values: {}, exceeds the maximum size of 2^16 - 1", value_size));
 
        m_bytecode.push_back(VAL_TABLE_START);
        serializeOn2BytesToVecBE(value_size, m_bytecode);
 
        for (const ValTableElem& val : values)
        {
            switch (val.type)
            {
                case ValTableElemType::Number:
                {
                    m_bytecode.push_back(NUMBER_TYPE);
                    const auto n = std::get<double>(val.value);
                    const auto [exponent, mantissa] = ieee754::serialize(n);
                    serializeToVecLE(exponent, m_bytecode);
                    serializeToVecLE(mantissa, m_bytecode);
                    break;
                }
 
                case ValTableElemType::String:
                {
                    m_bytecode.push_back(STRING_TYPE);
                    auto t = std::get<std::string>(val.value);
                    std::ranges::transform(t, std::back_inserter(m_bytecode), [](const char i) {
                        return static_cast<uint8_t>(i);
                    });
                    break;
                }
 
                case ValTableElemType::PageAddr:
                {
                    m_bytecode.push_back(FUNC_TYPE);
                    const std::size_t addr = std::get<std::size_t>(val.value);
                    serializeOn2BytesToVecBE(addr, m_bytecode);
                    break;
                }
            }
 
            m_bytecode.push_back(0_u8);
        }
    }
 
    void IRCompiler::pushFilenameTable()
    {
        if (m_filenames.size() > std::numeric_limits<uint16_t>::max())
            throw std::overflow_error(fmt::format("Too many filenames: {}, exceeds the maximum size of 2^16 - 1", m_filenames.size()));
 
        m_bytecode.push_back(FILENAMES_TABLE_START);
        // push number of elements
        serializeOn2BytesToVecBE(m_filenames.size(), m_bytecode);
 
        for (const auto& name : m_filenames)
        {
            std::ranges::transform(name, std::back_inserter(m_bytecode), [](const char i) {
                return static_cast<uint8_t>(i);
            });
            m_bytecode.push_back(0_u8);
        }
    }
 
    void IRCompiler::pushInstLocTable(const std::vector<IR::Block>& pages)
    {
        std::vector<internal::InstLoc> locations;
        for (std::size_t i = 0, end = pages.size(); i < end; ++i)
        {
            const auto& page = pages[i];
            uint16_t ip = 0;
 
            for (const auto& inst : page)
            {
                if (inst.hasValidSourceLocation())
                {
                    // we are guaranteed to have a value since we listed all existing filenames in IRCompiler::process before,
                    // thus we do not have to check if std::ranges::find returned a valid iterator.
                    auto file_id = static_cast<uint16_t>(std::distance(m_filenames.begin(), std::ranges::find(m_filenames, inst.filename())));
 
                    std::optional<internal::InstLoc> prev = std::nullopt;
                    if (!locations.empty())
                        prev = locations.back();
 
                    // skip redundant instruction location
                    if (!(prev.has_value() && prev->filename_id == file_id && prev->line == inst.sourceLine() && prev->page_pointer == i))
                        locations.push_back(
                            { .page_pointer = static_cast<uint16_t>(i),
                              .inst_pointer = ip,
                              .filename_id = file_id,
                              .line = static_cast<uint32_t>(inst.sourceLine()) });
                }
 
                if (inst.kind() != IR::Kind::Label)
                    ++ip;
            }
        }
 
        m_bytecode.push_back(INST_LOC_TABLE_START);
        serializeOn2BytesToVecBE(locations.size(), m_bytecode);
 
        std::optional<internal::InstLoc> prev = std::nullopt;
 
        for (const auto& loc : locations)
        {
            serializeOn2BytesToVecBE(loc.page_pointer, m_bytecode);
            serializeOn2BytesToVecBE(loc.inst_pointer, m_bytecode);
            serializeOn2BytesToVecBE(loc.filename_id, m_bytecode);
            serializeToVecBE(loc.line, m_bytecode);
 
            prev = loc;
        }
    }
}