zeek/src/script_opt/ZAM/Driver.cc

// See the file "COPYING" in the main distribution directory for copyright.

// Driver (and other high-level) methods for ZAM compilation.

#include "zeek/Frame.h"
#include "zeek/Reporter.h"
#include "zeek/Scope.h"
#include "zeek/script_opt/ScriptOpt.h"
#include "zeek/script_opt/ZAM/Compile.h"

namespace zeek::detail {

ZAMCompiler::ZAMCompiler(ScriptFuncPtr f, std::shared_ptr<ProfileFuncs> _pfs, std::shared_ptr<ProfileFunc> _pf,
                         ScopePtr _scope, StmtPtr _body, std::shared_ptr<UseDefs> _ud, std::shared_ptr<Reducer> _rd) {
    func = std::move(f);
    pfs = std::move(_pfs);
    pf = std::move(_pf);
    scope = std::move(_scope);
    body = std::move(_body);
    ud = std::move(_ud);
    reducer = std::move(_rd);
    frame_sizeI = 0;

    auto loc = body->GetLocationInfo();
    ASSERT(loc->FirstLine() != 0 || body->Tag() == STMT_NULL);
    auto loc_copy = std::make_shared<Location>(loc->FileName(), loc->FirstLine(), loc->LastLine());
    ZAM::curr_func = func->GetName();
    ZAM::curr_loc = std::make_shared<ZAMLocInfo>(ZAM::curr_func, std::move(loc_copy), nullptr);

    Init();
}

ZAMCompiler::~ZAMCompiler() {
    for ( auto i : insts1 )
        delete i;
}

void ZAMCompiler::Init() {
    InitGlobals();
    InitArgs();
    InitCaptures();
    InitLocals();

    TrackMemoryManagement();

    non_recursive = non_recursive_funcs.contains(func.get());
}

void ZAMCompiler::InitGlobals() {
    for ( auto& g : pf->Globals() ) {
        GlobalInfo info{.id = g, .slot = AddToFrame(g)};
        global_id_to_info[g] = globalsI.size();
        globalsI.push_back(info);
    }
}

void ZAMCompiler::InitArgs() {
    auto uds = ud->HasUsage(body.get()) ? ud->GetUsage(body.get()) : nullptr;

    auto args = scope->OrderedVars();
    int nparam = func->GetType()->Params()->NumFields();

    push_existing_scope(scope);

    for ( auto& a : args ) {
        if ( --nparam < 0 )
            break;

        if ( uds && uds->HasID(a) )
            LoadParam(a);
        else {
            // printf("param %s unused\n", obj_desc(arg_id.get()));
        }
    }

    pop_scope();
}

void ZAMCompiler::InitCaptures() {
    for ( auto c : pf->Captures() )
        (void)AddToFrame(c);
}

void ZAMCompiler::InitLocals() {
    // Assign slots for locals (which includes temporaries).
    for ( auto& l : pf->Locals() ) {
        if ( IsCapture(l) )
            continue;

        if ( pf->WhenLocals().contains(l) )
            continue;

        // Don't add locals that were already added because they're
        // parameters.
        //
        // Don't worry about unused variables, those will get
        // removed during low-level ZAM optimization.
        if ( ! HasFrameSlot(l) )
            (void)AddToFrame(l);
    }
}

void ZAMCompiler::TrackMemoryManagement() {
    for ( auto& slot : frame_layout1 ) {
        // Look for locals with values of types for which
        // we do explicit memory management on (re)assignment.
        auto t = slot.first->GetType();
        if ( ZVal::IsManagedType(t) )
            managed_slotsI.push_back(slot.second);
    }
}

StmtPtr ZAMCompiler::CompileBody() {
    if ( func->Flavor() == FUNC_FLAVOR_HOOK )
        PushBreaks();

    (void)CompileStmt(body);

    if ( reporter->Errors() > 0 )
        return nullptr;

    ResolveHookBreaks();

    if ( ! nexts.empty() )
        reporter->Error("\"next\" used without an enclosing \"for\"");

    if ( ! fallthroughs.empty() )
        reporter->Error("\"fallthrough\" used without an enclosing \"switch\"");

    if ( ! catches.empty() )
        reporter->InternalError("untargeted inline return");

    // Make sure we have a (pseudo-)instruction at the end so we
    // can use it as a branch label.
    if ( ! pending_inst )
        pending_inst = new ZInstI();

    // Concretize instruction numbers in inst1 so we can
    // easily move through the code.
    for ( auto i = 0U; i < insts1.size(); ++i )
        insts1[i]->inst_num = i;

    ComputeLoopLevels();

    if ( ! analysis_options.no_ZAM_opt )
        OptimizeInsts();

    AdjustBranches();

    // Construct the final program with the dead code eliminated
    // and branches resolved.

    // Make sure we don't include the empty pending-instruction, if any.
    if ( pending_inst )
        pending_inst->live = false;

    // Maps inst1 instructions to where they are in inst2.
    // Dead instructions map to -1.
    std::vector<int> inst1_to_inst2;

    for ( auto& i1 : insts1 ) {
        if ( i1->live ) {
            inst1_to_inst2.push_back(insts2.size());
            insts2.push_back(i1);
        }
        else
            inst1_to_inst2.push_back(-1);
    }

    // Re-concretize instruction numbers, and concretize GoTo's.
    for ( auto i = 0U; i < insts2.size(); ++i )
        insts2[i]->inst_num = i;

    RetargetBranches();

    // If we have remapped frame denizens, update them.  If not,
    // create them.
    if ( ! shared_frame_denizens.empty() )
        RemapFrameDenizens(inst1_to_inst2);

    else
        CreateSharedFrameDenizens();

    delete pending_inst;

    ConcretizeSwitches();

    auto fname = func->GetName();

    if ( func->Flavor() == FUNC_FLAVOR_FUNCTION )
        fname = func_name_at_loc(fname, body->GetLocationInfo());

    auto zb = make_intrusive<ZBody>(fname, this);
    zb->SetInsts(insts2);
    zb->SetLocationInfo(body->GetLocationInfo());

    // Could erase insts1 here to recover memory, but it's handy
    // for debugging.

    return zb;
}

void ZAMCompiler::ResolveHookBreaks() {
    if ( ! breaks.empty() ) {
        ASSERT(breaks.size() == 1);

        if ( func->Flavor() == FUNC_FLAVOR_HOOK ) {
            // Rewrite the breaks.
            for ( auto& b : breaks[0] ) {
                auto& i = insts1[b.stmt_num];
                auto aux = i->aux;
                *i = ZInstI(OP_HOOK_BREAK_X);
                i->aux = aux;
            }
        }

        else
            reporter->Error("\"break\" used without an enclosing \"for\" or \"switch\"");
    }
}

void ZAMCompiler::ComputeLoopLevels() {
    // Compute which instructions are inside loops.
    for ( auto i = 0; i < int(insts1.size()); ++i ) {
        auto inst = insts1[i];

        auto t = inst->target;
        if ( ! t || t == pending_inst )
            continue;

        if ( t->inst_num < i ) {
            auto j = t->inst_num;

            if ( ! t->loop_start ) {
                // Loop is newly discovered.
                t->loop_start = true;
            }
            else {
                // We're extending an existing loop.  Find
                // its current end.
                auto depth = t->loop_depth;
                while ( j < i && insts1[j]->loop_depth >= depth )
                    ++j;

                ASSERT(insts1[j]->loop_depth == depth - 1);
            }

            // Run from j's current position to i, bumping
            // the loop depth.
            while ( j <= i ) {
                ++insts1[j]->loop_depth;
                ++j;
            }
        }
    }
}

void ZAMCompiler::AdjustBranches() {
    // Move branches to dead code forward to their successor live code.
    for ( auto& inst : insts1 ) {
        if ( ! inst->live )
            continue;

        if ( auto t = inst->target )
            inst->target = FindLiveTarget(t);
    }

    // Fix up the implicit branches in switches, too.
    AdjustSwitchTables(int_casesI);
    AdjustSwitchTables(uint_casesI);
    AdjustSwitchTables(double_casesI);
    AdjustSwitchTables(str_casesI);
}

template<typename T>
void ZAMCompiler::AdjustSwitchTables(CaseMapsI<T>& abstract_cases) {
    for ( auto& targs : abstract_cases ) {
        for ( auto& targ : targs )
            targ.second = FindLiveTarget(targ.second);
    }
}

void ZAMCompiler::RetargetBranches() {
    for ( auto& inst : insts2 )
        if ( inst->target )
            ConcretizeBranch(inst, inst->target, inst->target_slot);
}

void ZAMCompiler::RemapFrameDenizens(const std::vector<int>& inst1_to_inst2) {
    for ( auto& info : shared_frame_denizens ) {
        for ( auto& start : info.id_start ) {
            // It can happen that the identifier's
            // origination instruction was optimized
            // away, if due to slot sharing it's of
            // the form "slotX = slotX".  In that
            // case, look forward for the next viable
            // instruction.
            while ( start < insts1.size() && inst1_to_inst2[start] == -1 )
                ++start;

            ASSERT(start < insts1.size());
            start = inst1_to_inst2[start];
        }

        shared_frame_denizens_final.push_back(info);
    }
}

void ZAMCompiler::CreateSharedFrameDenizens() {
    for ( auto& fd : frame_denizens ) {
        FrameSharingInfo info;
        info.ids.push_back(fd);
        info.id_start.push_back(0);
        info.scope_end = insts2.size();

        // The following doesn't matter since the value
        // is only used during compiling, not during
        // execution.
        info.is_managed = false;

        shared_frame_denizens_final.push_back(std::move(info));
    }
}

void ZAMCompiler::ConcretizeSwitches() {
    // Create concretized versions of any case tables.
    ConcretizeSwitchTables(int_casesI, int_cases);
    ConcretizeSwitchTables(uint_casesI, uint_cases);
    ConcretizeSwitchTables(double_casesI, double_cases);
    ConcretizeSwitchTables(str_casesI, str_cases);
}

template<typename T>
void ZAMCompiler::ConcretizeSwitchTables(const CaseMapsI<T>& abstract_cases, CaseMaps<T>& concrete_cases) {
    for ( auto& targs : abstract_cases ) {
        CaseMap<T> cm;
        for ( auto& targ : targs )
            cm[targ.first] = targ.second->inst_num;
        concrete_cases.emplace_back(cm);
    }
}

#include "ZAM-MethodDefs.h"

void ZAMCompiler::Dump() {
    bool remapped_frame = ! analysis_options.no_ZAM_opt;

    if ( analysis_options.dump_ZAM ) {
        if ( remapped_frame )
            printf("\nOriginal frame for %s:\n", func->GetName().c_str());

        for ( const auto& elem : frame_layout1 )
            printf("frame[%d] = %s\n", elem.second, elem.first->Name());

        if ( remapped_frame ) {
            printf("Final frame for %s:\n", func->GetName().c_str());

            for ( auto i = 0U; i < shared_frame_denizens.size(); ++i ) {
                printf("frame2[%d] =", i);
                for ( auto& id : shared_frame_denizens[i].ids )
                    printf(" %s", id->Name());
                printf("\n");
            }
        }

        if ( ! insts2.empty() )
            printf("Pre-removal of dead code for %s:\n", func->GetName().c_str());

        auto remappings = remapped_frame ? &shared_frame_denizens : nullptr;

        DumpInsts1(remappings);

        if ( ! insts2.empty() )
            printf("Final intermediary code for %s:\n", func->GetName().c_str());

        remappings = remapped_frame ? &shared_frame_denizens_final : nullptr;

        for ( auto i = 0U; i < insts2.size(); ++i ) {
            auto& inst = insts2[i];
            std::string liveness;
            std::string depth;

            if ( inst->live )
                liveness = util::fmt("(labels %d)", inst->num_labels);
            else
                liveness = "(dead)";

            if ( inst->loop_depth )
                depth = util::fmt(" (loop %d)", inst->loop_depth);

            printf("%d %s%s: ", i, liveness.c_str(), depth.c_str());

            inst->Dump(stdout, &frame_denizens, remappings);
        }
    }
    else if ( analysis_options.dump_final_ZAM ) {
        printf("\nFrame for %s:\n", func->GetName().c_str());

        if ( remapped_frame ) {
            for ( auto i = 0U; i < shared_frame_denizens.size(); ++i ) {
                printf("frame[%d] =", i);
                for ( auto& id : shared_frame_denizens[i].ids )
                    printf(" %s", id->Name());
                printf("\n");
            }
        }
        else
            for ( const auto& elem : frame_layout1 )
                printf("frame[%d] = %s\n", elem.second, elem.first->Name());
    }

    if ( ! insts2.empty() )
        printf("Final code for %s:\n", func->GetName().c_str());

    auto remappings = remapped_frame ? &shared_frame_denizens_final : nullptr;
    for ( auto i = 0U; i < insts2.size(); ++i ) {
        auto& inst = insts2[i];
        // printf("%s:%d\n", inst->loc->filename, inst->loc->first_line);
        printf("%d: ", i);
        inst->Dump(stdout, &frame_denizens, remappings);
    }

    DumpCases(int_cases, "int");
    DumpCases(uint_cases, "uint");
    DumpCases(double_cases, "double");
    DumpCases(str_cases, "str");
}

template<typename T>
void ZAMCompiler::DumpCases(const CaseMaps<T>& cases, const char* type_name) const {
    for ( auto i = 0U; i < cases.size(); ++i ) {
        printf("%s switch table #%d:", type_name, i);
        for ( auto& m : cases[i] ) {
            std::string case_val;
            if constexpr ( std::is_same_v<T, std::string> )
                case_val = m.first;
            else if constexpr ( std::is_same_v<T, zeek_int_t> || std::is_same_v<T, zeek_uint_t> ||
                                std::is_same_v<T, double> )
                case_val = std::to_string(m.first);

            printf(" %s->%d", case_val.c_str(), m.second);
        }
        printf("\n");
    }
}

void ZAMCompiler::DumpInsts1(const FrameReMap* remappings) {
    for ( auto i = 0U; i < insts1.size(); ++i ) {
        auto& inst = insts1[i];

        if ( inst->target )
            // To get meaningful branch information in the dump,
            // we need to concretize the branch slots
            ConcretizeBranch(inst, inst->target, inst->target_slot);

        std::string liveness;
        std::string depth;

        if ( inst->live )
            liveness = util::fmt("(labels %d)", inst->num_labels);
        else
            liveness = "(dead)";

        if ( inst->loop_depth )
            depth = util::fmt(" (loop %d)", inst->loop_depth);

        printf("%d %s%s: ", i, liveness.c_str(), depth.c_str());

        inst->Dump(stdout, &frame_denizens, remappings);
    }
}

} // namespace zeek::detail