Source/JavaScriptCore/wasm/js/WebAssemblyFunctionBase.h

/*
 * Copyright (C) 2017-2021 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
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 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
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#pragma once

#if ENABLE(WEBASSEMBLY)

#include "JSFunction.h"
#include "WasmFormat.h"

namespace JSC {

class JSGlobalObject;
class JSWebAssemblyInstance;
using Wasm::WasmToWasmImportableFunction;

class WebAssemblyFunctionBase : public JSFunction {
public:
    using Base = JSFunction;

    static constexpr unsigned StructureFlags = Base::StructureFlags;

    DECLARE_INFO;

    JSWebAssemblyInstance* instance() const { return m_instance.get(); }

    Wasm::TypeIndex typeIndex() const { return m_importableFunction.typeIndex; }
    WasmToWasmImportableFunction::LoadLocation entrypointLoadLocation() const { return m_importableFunction.entrypointLoadLocation; }
    WasmToWasmImportableFunction importableFunction() const { return m_importableFunction; }

    static ptrdiff_t offsetOfInstance() { return OBJECT_OFFSETOF(WebAssemblyFunctionBase, m_instance); }

    static ptrdiff_t offsetOfSignatureIndex() { return OBJECT_OFFSETOF(WebAssemblyFunctionBase, m_importableFunction) + WasmToWasmImportableFunction::offsetOfSignatureIndex(); }

    static ptrdiff_t offsetOfEntrypointLoadLocation() { return OBJECT_OFFSETOF(WebAssemblyFunctionBase, m_importableFunction) + WasmToWasmImportableFunction::offsetOfEntrypointLoadLocation(); }

protected:
    DECLARE_VISIT_CHILDREN;
    void finishCreation(VM&, NativeExecutable*, unsigned length, const String& name, JSWebAssemblyInstance*);
    WebAssemblyFunctionBase(VM&, NativeExecutable*, JSGlobalObject*, Structure*, WasmToWasmImportableFunction);

    WriteBarrier<JSWebAssemblyInstance> m_instance;

    // It's safe to just hold the raw WasmToWasmImportableFunction because we have a reference
    // to our Instance, which points to the CodeBlock, which points to the Module
    // that exported us, which ensures that the actual Signature/code doesn't get deallocated.
    WasmToWasmImportableFunction m_importableFunction;
};

} // namespace JSC

#endif // ENABLE(WEBASSEMBLY)