/*
 * Copyright (C) 2025 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

#if ENABLE(WEBASSEMBLY)

#include <JavaScriptCore/WasmCallingConvention.h>
#include <wtf/Expected.h>
#include <wtf/text/WTFString.h>

namespace JSC::Wasm {

class CallSlot {
public:
    uint32_t count() const { return m_count; }

    void incrementCount()
    {
        ++m_count;
    }

    void observeCrossInstanceCall()
    {
        m_boxedCallee = megamorphicCallee;
    }

    void observeCallIndirect(EncodedJSValue boxedCallee)
    {
        if (m_boxedCallee == boxedCallee)
            return;

        if (!m_boxedCallee) {
            m_boxedCallee = boxedCallee;
            return;
        }

        // Initially, we are giving up for polymorphic calls.
        m_boxedCallee = megamorphicCallee;
    }

    EncodedJSValue boxedCallee() const { return m_boxedCallee; }

    static constexpr ptrdiff_t offsetOfCount() { return OBJECT_OFFSETOF(CallSlot, m_count); }
    static constexpr ptrdiff_t offsetOfBoxedCallee() { return OBJECT_OFFSETOF(CallSlot, m_boxedCallee); }

    static constexpr EncodedJSValue initCallee = 0b00;
    static constexpr EncodedJSValue polymorphicCallee = 0b01;
    static constexpr EncodedJSValue megamorphicCallee = 0b11;

private:
    uint32_t m_count { 0 };
    EncodedJSValue m_boxedCallee { initCallee };
};

} // namespace JSC::Wasm

#endif // ENABLE(WEBASSEMBLY)
