tools/RecyclerChecker/RecyclerChecker.cpp

//-------------------------------------------------------------------------------------------------------
// Copyright (C) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
//-------------------------------------------------------------------------------------------------------
#include "RecyclerChecker.h"

MainVisitor::MainVisitor(
        CompilerInstance& compilerInstance, ASTContext& context, bool fix)
    : _compilerInstance(compilerInstance), _context(context),
     _fix(fix), _fixed(false), _diagEngine(context.getDiagnostics()),
     _barrierTypeDefined(false)
{
    if (_fix)
    {
        _rewriter.setSourceMgr(compilerInstance.getSourceManager(),
                               compilerInstance.getLangOpts());
    }

#define SWB_WIKI \
    "https://github.com/microsoft/ChakraCore/wiki/Software-Write-Barrier#coding-rules"

    _diagUnbarrieredField = _diagEngine.getCustomDiagID(
        DiagnosticsEngine::Error,
        "Unbarriered field, see " SWB_WIKI);
   _diagIllegalBarrierCast = _diagEngine.getCustomDiagID(
        DiagnosticsEngine::Error,
        "Illegal casting away of write barrier, see " SWB_WIKI);
#undef SWB_WIKI
}

void MainVisitor::ReportUnbarriedField(SourceLocation location)
{
    DiagReport(location, _diagUnbarrieredField);
}

void MainVisitor::ReportIllegalBarrierCast(SourceLocation location)
{
    DiagReport(location, _diagIllegalBarrierCast);
}

void MainVisitor::DiagReport(SourceLocation location, unsigned diagId)
{
    _diagEngine.Report(location, diagId);
}

bool MainVisitor::VisitCXXRecordDecl(CXXRecordDecl* recordDecl)
{
    if (Log::GetLevel() < Log::LogLevel::Verbose)
    {
        return true; // At least Verbose level, otherwise this not needed
    }

    std::string typeName = recordDecl->getQualifiedNameAsString();

    // Ignore (system/non-GC types) before seeing "Memory::NoWriteBarrierField"
    if (!_barrierTypeDefined)
    {
        if (typeName != "Memory::NoWriteBarrierField")
        {
            return true;
        }

        _barrierTypeDefined = true;
    }

    if (!recordDecl->hasDefinition())
    {
        return true;
    }

    bool hasUnbarrieredPointer = false;
    bool hasBarrieredField = false;

    for (auto field : recordDecl->fields())
    {
        const QualType qualType = field->getType();
        const Type* type = qualType.getTypePtr();

        auto fieldTypeName = qualType.getAsString();
        if (StartsWith(fieldTypeName, "typename WriteBarrierFieldTypeTraits") ||
            StartsWith(fieldTypeName, "const typename WriteBarrierFieldTypeTraits"))
        {
            // Note this only indicates the class is write-barrier annotated
            hasBarrieredField = true;
        }
        else if (type->isPointerType())
        {
            hasUnbarrieredPointer = true;
        }
        else if (type->isCompoundType())
        {
            // If the field is a compound type,
            // check if it is a fully barriered type or
            // has unprotected pointer fields
            if (Contains(_pointerClasses, fieldTypeName))
            {
                hasUnbarrieredPointer = true;
            }
            else if (Contains(_barrieredClasses, fieldTypeName))
            {
                hasBarrieredField = true;
            }
        }
    }

    if (hasUnbarrieredPointer)
    {
        _pointerClasses.insert(typeName);
    }
    else if (hasBarrieredField)
    {
        _barrieredClasses.insert(typeName);
    }

    return true;
}

template <class PushFieldType>
void MainVisitor::ProcessUnbarrieredFields(
    CXXRecordDecl* recordDecl, const PushFieldType& pushFieldType)
{
    std::string typeName = recordDecl->getQualifiedNameAsString();
    if (typeName == "Memory::WriteBarrierPtr")
    {
        return;  // Skip WriteBarrierPtr itself
    }

    const auto& sourceMgr = _compilerInstance.getSourceManager();

    for (auto field : recordDecl->fields())
    {
        const QualType qualType = field->getType();
        string fieldTypeName = qualType.getAsString();
        string fieldName = field->getNameAsString();

        if (StartsWith(fieldTypeName, "WriteBarrierPtr<") || // WriteBarrierPtr fields
            Contains(fieldTypeName, "_no_write_barrier_policy, ")) // FieldNoBarrier
        {
            continue; // skip
        }

        // If an annotated field type is struct/class/union (RecordType), the
        // field type in turn should likely be annotated.
        if (fieldTypeName.back() != '*'  // not "... *"
            &&
            (
                StartsWith(fieldTypeName, "typename WriteBarrierFieldTypeTraits") ||
                StartsWith(fieldTypeName, "WriteBarrierFieldTypeTraits") ||
                StartsWith(fieldTypeName, "const typename WriteBarrierFieldTypeTraits") ||
                StartsWith(fieldTypeName, "const WriteBarrierFieldTypeTraits") ||
                fieldName.length() == 0  // anonymous union/struct
            ))
        {
            auto originalType = qualType->getUnqualifiedDesugaredType();
            if (auto arrayType = dyn_cast<ArrayType>(originalType))
            {
                originalType = arrayType->getElementType()->getUnqualifiedDesugaredType();
            }

            string originalTypeName = QualType(originalType, 0).getAsString();
            if (isa<RecordType>(originalType) &&
                !StartsWith(originalTypeName, "class Memory::WriteBarrierPtr<"))
            {
                if (pushFieldType(originalType))
                {
                    Log::verbose() << "Queue field type: " << originalTypeName
                        << " (" << typeName << "::" << fieldName << ")\n";
                }
            }
        }
        else
        {
            SourceLocation location = field->getLocStart();
            if (this->_fix)
            {
                const char* begin = sourceMgr.getCharacterData(location);
                const char* end = begin;

                if (MatchType(fieldTypeName, begin, &end))
                {
                    _rewriter.ReplaceText(
                        location, end - begin,
                        GetFieldTypeAnnotation(qualType) + string(begin, end) +
                             (*end == ' ' ? ")" : ") "));
                    _fixed = true;
                    continue;
                }

                Log::errs() << "Fail to fix: " << fieldTypeName << " "
                            << fieldName << "\n";
            }

            ReportUnbarriedField(location);
        }
    }
}

static bool SkipSpace(const char*& p)
{
    if (*p == ' ')
    {
        ++p;
        return true;
    }

    return false;
}

template <size_t N>
static bool SkipPrefix(const char*& p, const char (&prefix)[N])
{
    if (StartsWith(p, prefix))
    {
        p += N - 1; // skip
        return true;
    }

    return false;
}

static bool SkipPrefix(const char*& p, const string& prefix)
{
    if (StartsWith(p, prefix))
    {
        p += prefix.length(); // skip
        return true;
    }

    return false;
}

static bool SkipTemplateParameters(const char*& p)
{
    if (*p == '<')
    {
        ++p;
        int left = 1;

        while (left && *p)
        {
            switch (*p++)
            {
                case '<': ++left; break;
                case '>': --left; break;
            }
        }

        return true;
    }

    return false;
}

bool MainVisitor::MatchType(const string& type, const char* source, const char** pSourceEnd)
{
    // try match type in source directly (clang "bool" type is "_Bool")
    if (SkipPrefix(source, type) || (type == "_Bool" && SkipPrefix(source, "bool")))
    {
        *pSourceEnd = source;
        return true;
    }

    const char* p = type.c_str();
    while (*p && *source)
    {
        if (SkipSpace(p) || SkipSpace(source))
        {
            continue;
        }

#define SKIP_EITHER_PREFIX(prefix) \
            (SkipPrefix(p, prefix) || SkipPrefix(source, prefix))
        if (SKIP_EITHER_PREFIX("const ") ||
            SKIP_EITHER_PREFIX("class ") ||
            SKIP_EITHER_PREFIX("struct ") ||
            SKIP_EITHER_PREFIX("union ") ||
            SKIP_EITHER_PREFIX("enum "))
        {
            continue;
        }
#undef SKIP_EITHER_PREFIX

        // type may contain [...] array specifier, while source has it after field name
        if (*p == '[')
        {
            while (*p && *p++ != ']');
            continue;
        }

        // skip <...> in both
        if (SkipTemplateParameters(p) || SkipTemplateParameters(source))
        {
            continue;
        }

        // type may contain fully qualified name but source may or may not
        const char* pSkipScopeType = strstr(p, "::");
        if (pSkipScopeType && !memchr(p, ' ', pSkipScopeType - p))
        {
            pSkipScopeType += 2;
            if (strncmp(source, p, pSkipScopeType - p) == 0)
            {
                source += pSkipScopeType - p;
            }
            p = pSkipScopeType;
            continue;
        }

        if (*p == *source)
        {
            while (*p && *source && *p == *source && !strchr("<>", *p))
            {
                ++p, ++source;
            }
            continue;
        }

        if (*p != *source)
        {
            return false;  // mismatch
        }
    }

    if (!*p && *source)  // type match completed and having remaining source
    {
        while (*(source - 1) == ' ') --source; // try to stop after a non-space char
        *pSourceEnd = source;
        return true;
    }

    return false;
}

const char* MainVisitor::GetFieldTypeAnnotation(QualType qtype)
{
    if (qtype->isPointerType())
    {
        auto type = qtype->getUnqualifiedDesugaredType()->getPointeeType().getTypePtr();
        const auto& i = _allocationTypes.find(type);
        if (i != _allocationTypes.end()
            && i->second == AllocationTypes::NonRecycler)
        {
            return "FieldNoBarrier(";
        }
    }

    return "Field(";
}

bool MainVisitor::VisitFunctionDecl(FunctionDecl* functionDecl)
{
    if (functionDecl->hasBody())
    {
        CheckAllocationsInFunctionVisitor visitor(this, functionDecl);

        visitor.TraverseDecl(functionDecl);
    }

    return true;
}

void MainVisitor::RecordAllocation(QualType qtype, AllocationTypes allocationType)
{
    auto type = qtype->getCanonicalTypeInternal().getTypePtr();
    _allocationTypes[type] |= allocationType;
}

void MainVisitor::RecordRecyclerAllocation(const string& allocationFunction, const string& type)
{
    _allocatorTypeMap[allocationFunction].insert(type);
}

template <class Set, class DumpItemFunc>
void MainVisitor::dump(const char* name, const Set& set, const DumpItemFunc& func)
{
    Log::verbose() << "-------------------------\n\n";
    Log::verbose() << name << "\n";
    Log::verbose() << "-------------------------\n\n";
    for (auto item : set)
    {
        func(Log::verbose(), item);
    }
    Log::verbose() << "-------------------------\n\n";
}

template <class Item>
void MainVisitor::dump(const char* name, const set<Item>& set)
{
    dump(name, set, [](raw_ostream& out, const Item& item)
    {
        out << "  " << item << "\n";
    });
}

void MainVisitor::dump(const char* name, const unordered_set<const Type*> set)
{
    dump(name, set, [&](raw_ostream& out, const Type* type)
    {
        out << "  " << QualType(type, 0).getAsString() << "\n";
    });
}

void MainVisitor::Inspect()
{
#define Dump(coll) dump(#coll, _##coll)
    Dump(pointerClasses);
    Dump(barrieredClasses);

    Log::verbose() << "Recycler allocations\n";
    for (auto item : _allocatorTypeMap)
    {
        dump(item.first.c_str(), item.second);
    }

    std::queue<const Type*> queue;  // queue of types to check
    std::unordered_set<const Type*> barrierTypes;  // set of types queued
    auto pushBarrierType = [&](const Type* type) -> bool
    {
        if (barrierTypes.insert(type).second)
        {
            queue.push(type);
            return true;
        }
        return false;
    };

    for (auto item : _allocationTypes)
    {
        if (item.second & AllocationTypes::WriteBarrier)
        {
            pushBarrierType(item.first);
        }
    }
    dump("WriteBarrier allocation types", barrierTypes);

    // Examine all barrierd types. They should be fully wb annotated.
    while (!queue.empty())
    {
        auto type = queue.front();
        queue.pop();

        auto r = type->getCanonicalTypeInternal()->getAsCXXRecordDecl();
        if (r)
        {
            auto typeName = r->getQualifiedNameAsString();
            ProcessUnbarrieredFields(r, pushBarrierType);

            // queue the type's base classes
            for (const auto& base: r->bases())
            {
                if (pushBarrierType(base.getType().getTypePtr()))
                {
                    Log::verbose() << "Queue base type: " << base.getType().getAsString()
                        << " (base of " << typeName << ")\n";
                }
            }
        }
    }

#undef Dump
}

bool MainVisitor::ApplyFix()
{
    return _fixed ? _rewriter.overwriteChangedFiles() : false;
}

static AllocationTypes CheckAllocationType(const CXXStaticCastExpr* castNode)
{
    QualType targetType = castNode->getTypeAsWritten();
    if (const IdentifierInfo* info = targetType.getBaseTypeIdentifier())
    {
        return info->getName().equals("Recycler") ?
                AllocationTypes::Recycler : AllocationTypes::NonRecycler;
    }
    else
    {
        // Unknown template dependent allocator types
        return AllocationTypes::Unknown;
    }
}

template <class A0, class A1, class T>
void CheckAllocationsInFunctionVisitor::VisitAllocate(
    const A0& getArg0, const A1& getArg1, const T& getAllocType)
{
    const Expr* firstArgNode = getArg0();

    // Check if the first argument (to new or AllocateArray) is a static cast
    // AllocatorNew/AllocateArray in Chakra always does a static_cast to the AllocatorType
    const CXXStaticCastExpr* castNode = nullptr;
    if (firstArgNode != nullptr &&
        (castNode = dyn_cast<CXXStaticCastExpr>(firstArgNode)))
    {
        QualType allocatedType = getAllocType();
        string allocatedTypeStr = allocatedType.getAsString();

        auto allocationType = CheckAllocationType(castNode);
        if (allocationType == AllocationTypes::Recycler)  // Recycler allocation
        {
            const Expr* secondArgNode = getArg1();

            // Chakra has two types of allocating functions- throwing and non-throwing
            // However, recycler allocations are always throwing, so the second parameter
            // should be the address of the allocator function
            auto unaryNode = cast<UnaryOperator>(secondArgNode);
            if (unaryNode != nullptr && unaryNode->getOpcode() == UnaryOperatorKind::UO_AddrOf)
            {
                Expr* subExpr = unaryNode->getSubExpr();
                if (DeclRefExpr* declRef = cast<DeclRefExpr>(subExpr))
                {
                    auto declNameInfo = declRef->getNameInfo();
                    auto allocationFunctionStr = declNameInfo.getName().getAsString();
                    _mainVisitor->RecordRecyclerAllocation(allocationFunctionStr, allocatedTypeStr);

                    if (!Contains(allocationFunctionStr, "Leaf"))
                    {
                        // Recycler write barrier allocation -- unless "Leaf" in allocFunc
                        allocationType = AllocationTypes::RecyclerWriteBarrier;
                    }
                }
                else
                {
                    Log::errs() << "ERROR: (internal) Expected DeclRefExpr:\n";
                    subExpr->dump();
                }
            }
            else if (auto mExpr = cast<MaterializeTemporaryExpr>(secondArgNode))
            {
                auto name = mExpr->GetTemporaryExpr()->IgnoreImpCasts()->getType().getAsString();
                if (StartsWith(name, "InfoBitsWrapper<")) // && Contains(name, "WithBarrierBit"))
                {
                    // RecyclerNewEnumClass, RecyclerNewWithInfoBits -- always have WithBarrier varients
                    allocationType = AllocationTypes::RecyclerWriteBarrier;
                }
            }
            else
            {
                Log::errs() << "ERROR: (internal) Expected unary node or MaterializeTemporaryExpr:\n";
                secondArgNode->dump();
            }
        }

        if (allocationType & AllocationTypes::WriteBarrier)
        {
            Log::verbose() << "In \"" << _functionDecl->getQualifiedNameAsString() << "\"\n";
            Log::verbose() << "  Allocating \"" << allocatedTypeStr << "\" in write barriered memory\n";
        }

        _mainVisitor->RecordAllocation(allocatedType, allocationType);
    }
}

bool CheckAllocationsInFunctionVisitor::VisitCXXNewExpr(CXXNewExpr* newExpr)
{
    if (newExpr->getNumPlacementArgs() > 1)
    {
        VisitAllocate(
            [=]() { return newExpr->getPlacementArg(0); },
            [=]() { return newExpr->getPlacementArg(1); },
            [=]() { return newExpr->getAllocatedType(); }
        );
    }

    return true;
}

bool CheckAllocationsInFunctionVisitor::VisitCallExpr(CallExpr* callExpr)
{
    // Check callExpr for AllocateArray
    auto callee = callExpr->getDirectCallee();
    if (callExpr->getNumArgs() == 3 &&
        callee &&
        callee->getName().equals("AllocateArray"))
    {
        VisitAllocate(
            [=]() { return callExpr->getArg(0); },
            [=]() { return callExpr->getArg(1); },
            [=]()
            {
                auto retType = callExpr->getCallReturnType(_mainVisitor->getContext());
                return QualType(retType->getAs<PointerType>()->getPointeeType());
            }
        );
    }

    return true;
}

// Check if type is a "Field() *" pointer type, or alternatively a pointer to
// any type in "alt" if provided.
bool CheckAllocationsInFunctionVisitor::IsFieldPointer(
    const QualType& qtype, const char* alt)
{
    if (qtype->isPointerType())
    {
        auto name = qtype->getPointeeType()
            .getDesugaredType(_mainVisitor->getContext()).getAsString();
        return StartsWith(name, "class Memory::WriteBarrierPtr<")
            || StartsWith(name, "typename WriteBarrierFieldTypeTraits<")
            || (alt && strstr(alt, name.c_str()));
    }

    return false;
}

bool CheckAllocationsInFunctionVisitor::CommonVisitCastExpr(CastExpr *cast)
{
    if (IsFieldPointer(cast->getSubExpr()->getType()) &&  // from Field() *
        cast->getType()->isPointerType() &&     // to a pointer type
        !IsFieldPointer(cast->getType(),        // not another Field() *
            "int|float|double|unsigned char"))  // not int/float/double/byte *
    {
        _mainVisitor->ReportIllegalBarrierCast(cast->getLocStart());

        if (Log::GetLevel() >= Log::LogLevel::Info)
        {
            cast->dumpColor();
            cast->getSubExpr()->getType()->getPointeeType()
                .getDesugaredType(_mainVisitor->getContext()).dump("CAST_FROM");
            cast->getType()->getPointeeType()
                .getDesugaredType(_mainVisitor->getContext()).dump("CAST_TO");
        }
    }

    return true;
}

void RecyclerCheckerConsumer::HandleTranslationUnit(ASTContext& context)
{
    MainVisitor mainVisitor(_compilerInstance, context, _fix);
    mainVisitor.TraverseDecl(context.getTranslationUnitDecl());

    mainVisitor.Inspect();
    mainVisitor.ApplyFix();
}

std::unique_ptr<ASTConsumer> RecyclerCheckerAction::CreateASTConsumer(
    CompilerInstance& compilerInstance, llvm::StringRef)
{
    return llvm::make_unique<RecyclerCheckerConsumer>(compilerInstance, _fix);
}

bool RecyclerCheckerAction::ParseArgs(
    const CompilerInstance& compilerInstance, const std::vector<std::string>& args)
{
    for (auto i = args.begin(); i != args.end(); i++)
    {
        if (*i == "-fix")
        {
            this->_fix = true;
        }
        else if (*i == "-info")
        {
            Log::SetLevel(Log::LogLevel::Info);
        }
        else if (*i == "-verbose")
        {
            Log::SetLevel(Log::LogLevel::Verbose);
        }
        else
        {
            Log::errs()
                << "ERROR: Unrecognized check-recycler option: " << *i << "\n"
                << "Supported options:\n"
                << "  -fix          Fix missing write barrier annotations"
                << "  -info         Log info messages\n"
                << "  -verbose      Log verbose messages\n";
            return false;
        }
    }

    return true;
}

static FrontendPluginRegistry::Add<RecyclerCheckerAction> recyclerPlugin(
    "check-recycler", "Checks the recycler allocations");