Source/JavaScriptCore/wasm/WasmEntryPlan.cpp

/*
 * Copyright (C) 2019 Apple Inc. All rights reserved.
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 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
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 *
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#include "config.h"
#include "WasmEntryPlan.h"

#include "WasmBinding.h"
#include <wtf/DataLog.h>
#include <wtf/Locker.h>
#include <wtf/MonotonicTime.h>
#include <wtf/StdLibExtras.h>
#include <wtf/SystemTracing.h>

#if ENABLE(WEBASSEMBLY)

namespace JSC { namespace Wasm {

namespace WasmEntryPlanInternal {
static constexpr bool verbose = false;
}

EntryPlan::EntryPlan(Context* context, Ref<ModuleInformation> info, AsyncWork work, CompletionTask&& task)
    : Base(context, WTFMove(info), WTFMove(task))
    , m_streamingParser(m_moduleInformation.get(), *this)
    , m_state(State::Validated)
    , m_asyncWork(work)
{
}

EntryPlan::EntryPlan(Context* context, Vector<uint8_t>&& source, AsyncWork work, CompletionTask&& task)
    : Base(context, WTFMove(task))
    , m_source(WTFMove(source))
    , m_streamingParser(m_moduleInformation.get(), *this)
    , m_state(State::Initial)
    , m_asyncWork(work)
{
}

const char* EntryPlan::stateString(State state)
{
    switch (state) {
    case State::Initial: return "Initial";
    case State::Validated: return "Validated";
    case State::Prepared: return "Prepared";
    case State::Compiled: return "Compiled";
    case State::Completed: return "Completed";
    }
    RELEASE_ASSERT_NOT_REACHED();
}

void EntryPlan::moveToState(State state)
{
    ASSERT(state >= m_state);
    dataLogLnIf(WasmEntryPlanInternal::verbose && state != m_state, "moving to state: ", stateString(state), " from state: ", stateString(m_state));
    m_state = state;
}

bool EntryPlan::parseAndValidateModule(const uint8_t* source, size_t sourceLength)
{
    if (m_state != State::Initial)
        return true;

    dataLogLnIf(WasmEntryPlanInternal::verbose, "starting validation");
    MonotonicTime startTime;
    if (WasmEntryPlanInternal::verbose || Options::reportCompileTimes())
        startTime = MonotonicTime::now();

    m_streamingParser.addBytes(source, sourceLength);
    {
        auto locker = holdLock(m_lock);
        if (failed())
            return false;
    }

    if (m_streamingParser.finalize() != StreamingParser::State::Finished) {
        fail(holdLock(m_lock), m_streamingParser.errorMessage());
        return false;
    }

    if (WasmEntryPlanInternal::verbose || Options::reportCompileTimes())
        dataLogLn("Took ", (MonotonicTime::now() - startTime).microseconds(), " us to validate module");

    moveToState(State::Validated);
    return true;
}

void EntryPlan::prepare()
{
    ASSERT(m_state == State::Validated);
    dataLogLnIf(WasmEntryPlanInternal::verbose, "Starting preparation");

    const auto& functions = m_moduleInformation->functions;
    m_numberOfFunctions = functions.size();
    if (!tryReserveCapacity(m_wasmToWasmExitStubs, m_moduleInformation->importFunctionSignatureIndices.size(), " WebAssembly to JavaScript stubs")
        || !tryReserveCapacity(m_unlinkedWasmToWasmCalls, functions.size(), " unlinked WebAssembly to WebAssembly calls"))
        return;

    m_unlinkedWasmToWasmCalls.resize(functions.size());

    for (unsigned importIndex = 0; importIndex < m_moduleInformation->imports.size(); ++importIndex) {
        Import* import = &m_moduleInformation->imports[importIndex];
        if (import->kind != ExternalKind::Function)
            continue;
        unsigned importFunctionIndex = m_wasmToWasmExitStubs.size();
        dataLogLnIf(WasmEntryPlanInternal::verbose, "Processing import function number ", importFunctionIndex, ": ", makeString(import->module), ": ", makeString(import->field));
        auto binding = wasmToWasm(importFunctionIndex);
        if (UNLIKELY(!binding)) {
            switch (binding.error()) {
            case BindingFailure::OutOfMemory:
                return fail(holdLock(m_lock), makeString("Out of executable memory at import ", String::number(importIndex)));
            }
            RELEASE_ASSERT_NOT_REACHED();
        }
        m_wasmToWasmExitStubs.uncheckedAppend(binding.value());
    }

    const uint32_t importFunctionCount = m_moduleInformation->importFunctionCount();
    for (const auto& exp : m_moduleInformation->exports) {
        if (exp.kindIndex >= importFunctionCount)
            m_exportedFunctionIndices.add(exp.kindIndex - importFunctionCount);
    }

    for (const auto& element : m_moduleInformation->elements) {
        for (const uint32_t functionIndex : element.functionIndices) {
            if (!Element::isNullFuncIndex(functionIndex) && functionIndex >= importFunctionCount)
                m_exportedFunctionIndices.add(functionIndex - importFunctionCount);
        }
    }

    if (m_moduleInformation->startFunctionIndexSpace && m_moduleInformation->startFunctionIndexSpace >= importFunctionCount)
        m_exportedFunctionIndices.add(*m_moduleInformation->startFunctionIndexSpace - importFunctionCount);

    if (!prepareImpl())
        return;

    moveToState(State::Prepared);
}

// We don't have a semaphore class... and this does kinda interesting things.
class EntryPlan::ThreadCountHolder {
public:
    ThreadCountHolder(EntryPlan& plan)
        : m_plan(plan)
    {
        LockHolder locker(m_plan.m_lock);
        m_plan.m_numberOfActiveThreads++;
    }

    ~ThreadCountHolder()
    {
        LockHolder locker(m_plan.m_lock);
        m_plan.m_numberOfActiveThreads--;

        if (!m_plan.m_numberOfActiveThreads && !m_plan.hasWork())
            m_plan.complete(locker);
    }

    EntryPlan& m_plan;
};


void EntryPlan::compileFunctions(CompilationEffort effort)
{
    ASSERT(m_state >= State::Prepared);
    dataLogLnIf(WasmEntryPlanInternal::verbose, "Starting compilation");

    if (!hasWork())
        return;

    Optional<TraceScope> traceScope;
    if (Options::useTracePoints())
        traceScope.emplace(WebAssemblyCompileStart, WebAssemblyCompileEnd);
    ThreadCountHolder holder(*this);

    size_t bytesCompiled = 0;
    while (true) {
        if (effort == Partial && bytesCompiled >= Options::webAssemblyPartialCompileLimit())
            return;

        uint32_t functionIndex;
        {
            auto locker = holdLock(m_lock);
            if (m_currentIndex >= m_numberOfFunctions) {
                if (hasWork())
                    moveToState(State::Compiled);
                return;
            }
            functionIndex = m_currentIndex;
            ++m_currentIndex;
        }

        compileFunction(functionIndex);
        bytesCompiled += m_moduleInformation->functions[functionIndex].data.size();
    }
}

void EntryPlan::complete(const AbstractLocker& locker)
{
    ASSERT(m_state != State::Compiled || m_currentIndex >= m_moduleInformation->functions.size());
    dataLogLnIf(WasmEntryPlanInternal::verbose, "Starting Completion");

    if (!failed() && m_state == State::Compiled)
        didCompleteCompilation(locker);

    if (!isComplete()) {
        moveToState(State::Completed);
        runCompletionTasks(locker);
    }
}


} } // namespace JSC::Wasm

#endif // ENABLE(WEBASSEMBLY)