Source/JavaScriptCore/runtime/TypeProfilerLog.cpp

/*
 * Copyright (C) 2014-2019 Apple Inc. All rights reserved.
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 *     notice, this list of conditions and the following disclaimer.
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
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#include "config.h"
#include "TypeProfilerLog.h"

#include "JSCInlines.h"
#include "SlotVisitor.h"
#include "TypeLocation.h"


namespace JSC {

namespace TypeProfilerLogInternal {
static constexpr bool verbose = false;
}

TypeProfilerLog::TypeProfilerLog(VM& vm)
    : m_vm(vm)
    , m_logSize(50000)
    , m_logStartPtr(new LogEntry[m_logSize])
    , m_currentLogEntryPtr(m_logStartPtr)
    , m_logEndPtr(m_logStartPtr + m_logSize)
{
    ASSERT(m_logStartPtr);
}

TypeProfilerLog::~TypeProfilerLog()
{
    delete[] m_logStartPtr;
}

void TypeProfilerLog::processLogEntries(VM& vm, const String& reason)
{
    // We need to do this because this code will call into calculatedDisplayName.
    // calculatedDisplayName will clear any exception it sees (because it thinks
    // it's a stack overflow). We may be called when an exception was already
    // thrown, so we don't want calcualtedDisplayName to clear that exception that
    // was thrown before we even got here.
    VM::DeferExceptionScope deferExceptionScope(vm);

    MonotonicTime before { };
    if (TypeProfilerLogInternal::verbose) {
        dataLog("Process caller:'", reason, "'");
        before = MonotonicTime::now();
    }

    HashMap<Structure*, RefPtr<StructureShape>> cachedMonoProtoShapes;
    HashMap<std::pair<Structure*, JSCell*>, RefPtr<StructureShape>> cachedPolyProtoShapes;

    LogEntry* entry = m_logStartPtr;

    while (entry != m_currentLogEntryPtr) {
        StructureID id = entry->structureID;
        RefPtr<StructureShape> shape;
        JSValue value = entry->value;
        Structure* structure = nullptr;
        bool sawPolyProtoStructure = false;
        if (id) {
            structure = Heap::heap(value.asCell())->structureIDTable().get(id);
            auto iter = cachedMonoProtoShapes.find(structure);
            if (iter == cachedMonoProtoShapes.end()) {
                auto key = std::make_pair(structure, value.asCell());
                auto iter = cachedPolyProtoShapes.find(key);
                if (iter != cachedPolyProtoShapes.end()) {
                    shape = iter->value;
                    sawPolyProtoStructure = true;
                }

                if (!shape) {
                    shape = structure->toStructureShape(value, sawPolyProtoStructure);
                    if (sawPolyProtoStructure)
                        cachedPolyProtoShapes.set(key, shape);
                    else
                        cachedMonoProtoShapes.set(structure, shape);
                }
            } else
                shape = iter->value;
        }

        RuntimeType type = runtimeTypeForValue(m_vm, value);
        TypeLocation* location = entry->location;
        location->m_lastSeenType = type;
        if (location->m_globalTypeSet)
            location->m_globalTypeSet->addTypeInformation(type, shape.copyRef(), structure, sawPolyProtoStructure);
        location->m_instructionTypeSet->addTypeInformation(type, WTFMove(shape), structure, sawPolyProtoStructure);

        entry++;
    }

    // Note that we don't update this cursor until we're done processing the log.
    // This allows us to have a sane story in case we have to mark the log
    // while processing through it. We won't be iterating over the log while
    // marking it, but we may be in the middle of iterating over when the mutator
    // pauses and causes the collector to mark the log.
    m_currentLogEntryPtr = m_logStartPtr;

    if (TypeProfilerLogInternal::verbose) {
        MonotonicTime after = MonotonicTime::now();
        dataLogF(" Processing the log took: '%f' ms\n", (after - before).milliseconds());
    }
}

void TypeProfilerLog::visit(SlotVisitor& visitor)
{
    for (LogEntry* entry = m_logStartPtr; entry != m_currentLogEntryPtr; ++entry) {
        visitor.appendUnbarriered(entry->value);
        if (StructureID id = entry->structureID) {
            Structure* structure = visitor.heap()->structureIDTable().get(id); 
            visitor.appendUnbarriered(structure);
        }
    }
}

} // namespace JSC