jitcode.h

linux下开源浏览器WebKit的源码,市面上的很多商用浏览器都是移植自WebKit

/*
 * Copyright (C) 2008 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. 
 */

#ifndef JITCode_h
#define JITCode_h

#include <wtf/Platform.h>

#if ENABLE(JIT)

#include "CallFrame.h"
#include "JSValue.h"
#include "Profiler.h"

namespace JSC {

    class JSGlobalData;
    class RegisterFile;

    extern "C" {
        JSValueEncodedAsPointer* ctiTrampoline(
#if PLATFORM(X86_64)
            // FIXME: (bug #22910) this will force all arguments onto the stack (regparm(0) does not appear to have any effect).
            // We can allow register passing here, and move the writes of these values into the trampoline.
            void*, void*, void*, void*, void*, void*,
#endif
            void* code, RegisterFile*, CallFrame*, JSValuePtr* exception, Profiler**, JSGlobalData*);
    };

    class JITCode {
    public:
        JITCode(void* code)
            : code(code)
        {
        }

        operator bool()
        {
            return code != 0;
        }

        void* addressForCall()
        {
            return code;
        }

        // This function returns the offset in bytes of 'pointerIntoCode' into
        // this block of code.  The pointer provided must be a pointer into this
        // block of code.  It is ASSERTed that no codeblock >4gb in size.
        unsigned offsetOf(void* pointerIntoCode)
        {
            intptr_t result = reinterpret_cast<intptr_t>(pointerIntoCode) - reinterpret_cast<intptr_t>(code);
            ASSERT(static_cast<intptr_t>(static_cast<unsigned>(result)) == result);
            return static_cast<unsigned>(result);
        }

        // Execute the code!
        inline JSValuePtr execute(RegisterFile* registerFile, CallFrame* callFrame, JSGlobalData* globalData, JSValuePtr* exception)
        {
            return JSValuePtr::decode(ctiTrampoline(
#if PLATFORM(X86_64)
                0, 0, 0, 0, 0, 0,
#endif
                code, registerFile, callFrame, exception, Profiler::enabledProfilerReference(), globalData));
        }

    private:
        void* code;
    };

};

#endif

#endif