Source/JavaScriptCore/bytecode/UnlinkedFunctionExecutable.h

/*
 * Copyright (C) 2012-2019 Apple Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include "CodeSpecializationKind.h"
#include "ConstructAbility.h"
#include "ConstructorKind.h"
#include "ExecutableInfo.h"
#include "ExpressionRangeInfo.h"
#include "Identifier.h"
#include "Intrinsic.h"
#include "JSCast.h"
#include "ParserModes.h"
#include "ParserTokens.h"
#include "RegExp.h"
#include "SourceCode.h"
#include "VariableEnvironment.h"
#include <wtf/Optional.h>

namespace JSC {

class Decoder;
class FunctionMetadataNode;
class FunctionExecutable;
class ParserError;
class SourceProvider;
class UnlinkedFunctionCodeBlock;
class CachedFunctionExecutable;

enum UnlinkedFunctionKind {
    UnlinkedNormalFunction,
    UnlinkedBuiltinFunction,
};

class UnlinkedFunctionExecutable final : public JSCell {
public:
    friend class CodeCache;
    friend class VM;
    friend class CachedFunctionExecutable;

    typedef JSCell Base;
    static constexpr unsigned StructureFlags = Base::StructureFlags | StructureIsImmortal;

    template<typename CellType, SubspaceAccess>
    static IsoSubspace* subspaceFor(VM& vm)
    {
        return &vm.unlinkedFunctionExecutableSpace.space;
    }

    static UnlinkedFunctionExecutable* create(VM& vm, const SourceCode& source, FunctionMetadataNode* node, UnlinkedFunctionKind unlinkedFunctionKind, ConstructAbility constructAbility, JSParserScriptMode scriptMode, Optional<CompactVariableMap::Handle> parentScopeTDZVariables, DerivedContextType derivedContextType, NeedsClassFieldInitializer needsClassFieldInitializer, bool isBuiltinDefaultClassConstructor = false)
    {
        UnlinkedFunctionExecutable* instance = new (NotNull, allocateCell<UnlinkedFunctionExecutable>(vm.heap))
            UnlinkedFunctionExecutable(vm, vm.unlinkedFunctionExecutableStructure.get(), source, node, unlinkedFunctionKind, constructAbility, scriptMode, WTFMove(parentScopeTDZVariables), derivedContextType, needsClassFieldInitializer, isBuiltinDefaultClassConstructor);
        instance->finishCreation(vm);
        return instance;
    }

    ~UnlinkedFunctionExecutable();

    const Identifier& name() const { return m_name; }
    const Identifier& ecmaName() const { return m_ecmaName; }
    void setEcmaName(const Identifier& name) { m_ecmaName = name; }
    unsigned parameterCount() const { return m_parameterCount; }; // Excluding 'this'!
    SourceParseMode parseMode() const { return static_cast<SourceParseMode>(m_sourceParseMode); };

    SourceCode classSource() const
    {
        if (m_rareData)
            return m_rareData->m_classSource;
        return SourceCode();
    }
    void setClassSource(const SourceCode& source)
    {
        ensureRareData().m_classSource = source;
    }

    bool isInStrictContext() const { return m_isInStrictContext; }
    FunctionMode functionMode() const { return static_cast<FunctionMode>(m_functionMode); }
    ConstructorKind constructorKind() const { return static_cast<ConstructorKind>(m_constructorKind); }
    SuperBinding superBinding() const { return static_cast<SuperBinding>(m_superBinding); }

    unsigned lineCount() const { return m_lineCount; }
    unsigned linkedStartColumn(unsigned parentStartColumn) const { return m_unlinkedBodyStartColumn + (!m_firstLineOffset ? parentStartColumn : 1); }
    unsigned linkedEndColumn(unsigned startColumn) const { return m_unlinkedBodyEndColumn + (!m_lineCount ? startColumn : 1); }

    unsigned unlinkedFunctionNameStart() const { return m_unlinkedFunctionNameStart; }
    unsigned unlinkedBodyStartColumn() const { return m_unlinkedBodyStartColumn; }
    unsigned unlinkedBodyEndColumn() const { return m_unlinkedBodyEndColumn; }
    unsigned startOffset() const { return m_startOffset; }
    unsigned sourceLength() { return m_sourceLength; }
    unsigned parametersStartOffset() const { return m_parametersStartOffset; }
    unsigned typeProfilingStartOffset() const { return m_typeProfilingStartOffset; }
    unsigned typeProfilingEndOffset() const { return m_typeProfilingEndOffset; }
    void setInvalidTypeProfilingOffsets();

    UnlinkedFunctionCodeBlock* unlinkedCodeBlockFor(
        VM&, const SourceCode&, CodeSpecializationKind, OptionSet<CodeGenerationMode>,
        ParserError&, SourceParseMode);

    static UnlinkedFunctionExecutable* fromGlobalCode(
        const Identifier&, JSGlobalObject*, const SourceCode&, JSObject*& exception, 
        int overrideLineNumber, Optional<int> functionConstructorParametersEndPosition);

    SourceCode linkedSourceCode(const SourceCode&) const;
    JS_EXPORT_PRIVATE FunctionExecutable* link(VM&, ScriptExecutable* topLevelExecutable, const SourceCode& parentSource, Optional<int> overrideLineNumber = WTF::nullopt, Intrinsic = NoIntrinsic, bool isInsideOrdinaryFunction = false);

    void clearCode(VM& vm)
    {
        m_unlinkedCodeBlockForCall.clear();
        m_unlinkedCodeBlockForConstruct.clear();
        vm.unlinkedFunctionExecutableSpace.set.remove(this);
    }

    void recordParse(CodeFeatures features, bool hasCapturedVariables)
    {
        m_features = features;
        m_hasCapturedVariables = hasCapturedVariables;
    }

    CodeFeatures features() const { return m_features; }
    bool hasCapturedVariables() const { return m_hasCapturedVariables; }

    static constexpr bool needsDestruction = true;
    static void destroy(JSCell*);

    bool isBuiltinFunction() const { return m_isBuiltinFunction; }
    ConstructAbility constructAbility() const { return static_cast<ConstructAbility>(m_constructAbility); }
    JSParserScriptMode scriptMode() const { return static_cast<JSParserScriptMode>(m_scriptMode); }
    bool isClassConstructorFunction() const
    {
        switch (constructorKind()) {
        case ConstructorKind::None:
        case ConstructorKind::Naked:
            return false;
        case ConstructorKind::Base:
        case ConstructorKind::Extends:
            return true;
        }
        return false;
    }
    bool isClass() const
    {
        if (!m_rareData)
            return false;
        return !m_rareData->m_classSource.isNull();
    }

    VariableEnvironment parentScopeTDZVariables() const
    {
        if (!m_rareData || !m_rareData->m_parentScopeTDZVariables)
            return VariableEnvironment();
        return m_rareData->m_parentScopeTDZVariables.environment().toVariableEnvironment();
    }
    
    bool isArrowFunction() const { return isArrowFunctionParseMode(parseMode()); }

    JSC::DerivedContextType derivedContextType() const {return static_cast<JSC::DerivedContextType>(m_derivedContextType); }

    String sourceURLDirective() const
    {
        if (m_rareData)
            return m_rareData->m_sourceURLDirective;
        return String();
    }
    String sourceMappingURLDirective() const
    {
        if (m_rareData)
            return m_rareData->m_sourceMappingURLDirective;
        return String();
    }
    void setSourceURLDirective(const String& sourceURL)
    {
        ensureRareData().m_sourceURLDirective = sourceURL;
    }
    void setSourceMappingURLDirective(const String& sourceMappingURL)
    {
        ensureRareData().m_sourceMappingURLDirective = sourceMappingURL;
    }

    void finalizeUnconditionally(VM&);

    struct RareData {
        WTF_MAKE_STRUCT_FAST_ALLOCATED;

        SourceCode m_classSource;
        String m_sourceURLDirective;
        String m_sourceMappingURLDirective;
        CompactVariableMap::Handle m_parentScopeTDZVariables;
        Vector<JSTextPosition> m_instanceFieldLocations;
    };

    NeedsClassFieldInitializer needsClassFieldInitializer() const { return static_cast<NeedsClassFieldInitializer>(m_needsClassFieldInitializer); }

    Vector<JSTextPosition>* instanceFieldLocations() const
    {
        if (m_rareData)
            return &m_rareData->m_instanceFieldLocations;
        return nullptr;
    }

    void setInstanceFieldLocations(Vector<JSTextPosition>&& instanceFieldLocations)
    {
        if (instanceFieldLocations.isEmpty())
            return;
        ensureRareData().m_instanceFieldLocations = WTFMove(instanceFieldLocations);
    }

private:
    UnlinkedFunctionExecutable(VM&, Structure*, const SourceCode&, FunctionMetadataNode*, UnlinkedFunctionKind, ConstructAbility, JSParserScriptMode, Optional<CompactVariableMap::Handle>,  JSC::DerivedContextType, JSC::NeedsClassFieldInitializer, bool isBuiltinDefaultClassConstructor);
    UnlinkedFunctionExecutable(Decoder&, const CachedFunctionExecutable&);

    void decodeCachedCodeBlocks(VM&);

    bool codeBlockEdgeMayBeWeak() const
    {
        // Currently, bytecode cache assumes that the tree of UnlinkedFunctionExecutable and UnlinkedCodeBlock will not be destroyed while the parent is live.
        // Bytecode cache uses this asumption to avoid duplicate materialization by bookkeeping the heap cells in the offste-to-pointer map.
        return VM::useUnlinkedCodeBlockJettisoning() && !m_isGeneratedFromCache;
    }

    unsigned m_firstLineOffset : 31;
    unsigned m_isInStrictContext : 1;
    unsigned m_lineCount : 31;
    unsigned m_hasCapturedVariables : 1;
    unsigned m_unlinkedFunctionNameStart : 31;
    unsigned m_isBuiltinFunction : 1;
    unsigned m_unlinkedBodyStartColumn : 31;
    unsigned m_isBuiltinDefaultClassConstructor : 1;
    unsigned m_unlinkedBodyEndColumn : 31;
    unsigned m_constructAbility: 1;
    unsigned m_startOffset : 31;
    unsigned m_scriptMode: 1; // JSParserScriptMode
    unsigned m_sourceLength : 31;
    unsigned m_superBinding : 1;
    unsigned m_parametersStartOffset : 31;
    unsigned m_isCached : 1;
    unsigned m_typeProfilingStartOffset;
    unsigned m_typeProfilingEndOffset;
    unsigned m_parameterCount;
    CodeFeatures m_features;
    SourceParseMode m_sourceParseMode;
    unsigned m_constructorKind : 2;
    unsigned m_functionMode : 2; // FunctionMode
    unsigned m_derivedContextType: 2;
    unsigned m_isGeneratedFromCache : 1;
    unsigned m_needsClassFieldInitializer : 1;

    union {
        WriteBarrier<UnlinkedFunctionCodeBlock> m_unlinkedCodeBlockForCall;
        RefPtr<Decoder> m_decoder;
    };

    union {
        WriteBarrier<UnlinkedFunctionCodeBlock> m_unlinkedCodeBlockForConstruct;
        struct {
            int32_t m_cachedCodeBlockForCallOffset;
            int32_t m_cachedCodeBlockForConstructOffset;
        };
    };

    Identifier m_name;
    Identifier m_ecmaName;

    RareData& ensureRareData()
    {
        if (LIKELY(m_rareData))
            return *m_rareData;
        return ensureRareDataSlow();
    }
    RareData& ensureRareDataSlow();

    std::unique_ptr<RareData> m_rareData;

protected:
    static void visitChildren(JSCell*, SlotVisitor&);

public:
    static Structure* createStructure(VM& vm, JSGlobalObject* globalObject, JSValue proto)
    {
        return Structure::create(vm, globalObject, proto, TypeInfo(UnlinkedFunctionExecutableType, StructureFlags), info());
    }

    DECLARE_EXPORT_INFO;
};

} // namespace JSC