C++ JSFunction::structure方法代码示例

static bool attemptToOptimizeClosureCall(ExecState* execCallee, JSCell* calleeAsFunctionCell, CallLinkInfo& callLinkInfo)
{
    if (!calleeAsFunctionCell)
        return false;
    
    JSFunction* callee = jsCast<JSFunction*>(calleeAsFunctionCell);
    JSFunction* oldCallee = callLinkInfo.callee.get();
    
    if (!oldCallee
        || oldCallee->structure() != callee->structure()
        || oldCallee->executable() != callee->executable())
        return false;
    
    ASSERT(callee->executable()->hasJITCodeForCall());
    MacroAssemblerCodePtr codePtr = callee->executable()->generatedJITCodeForCall()->addressForCall();
    
    CodeBlock* codeBlock;
    if (callee->executable()->isHostFunction())
        codeBlock = 0;
    else {
        codeBlock = jsCast<FunctionExecutable*>(callee->executable())->codeBlockForCall();
        if (execCallee->argumentCountIncludingThis() < static_cast<size_t>(codeBlock->numParameters()))
            return false;
    }
    
    linkClosureCall(
        execCallee, callLinkInfo, codeBlock,
        callee->structure(), callee->executable(), codePtr);
    
    return true;
}

CallLinkStatus CallLinkStatus::computeFor(CodeBlock* profiledBlock, unsigned bytecodeIndex)
{
    ConcurrentJITLocker locker(profiledBlock->m_lock);
    
    UNUSED_PARAM(profiledBlock);
    UNUSED_PARAM(bytecodeIndex);
#if ENABLE(JIT) && ENABLE(VALUE_PROFILER)
    if (!profiledBlock->hasBaselineJITProfiling())
        return computeFromLLInt(profiledBlock, bytecodeIndex);
    
    if (profiledBlock->couldTakeSlowCase(bytecodeIndex))
        return CallLinkStatus::takesSlowPath();
    
    CallLinkInfo& callLinkInfo = profiledBlock->getCallLinkInfo(bytecodeIndex);
    if (callLinkInfo.stub)
        return CallLinkStatus(callLinkInfo.stub->executable(), callLinkInfo.stub->structure());
    
    JSFunction* target = callLinkInfo.lastSeenCallee.get();
    if (!target)
        return computeFromLLInt(profiledBlock, bytecodeIndex);
    
    if (callLinkInfo.hasSeenClosure)
        return CallLinkStatus(target->executable(), target->structure());

    return CallLinkStatus(target);
#else
    return CallLinkStatus();
#endif
}

CallLinkStatus CallLinkStatus::computeFor(const ConcurrentJITLocker&, CallLinkInfo& callLinkInfo)
{
    // Note that despite requiring that the locker is held, this code is racy with respect
    // to the CallLinkInfo: it may get cleared while this code runs! This is because
    // CallLinkInfo::unlink() may be called from a different CodeBlock than the one that owns
    // the CallLinkInfo and currently we save space by not having CallLinkInfos know who owns
    // them. So, there is no way for either the caller of CallLinkInfo::unlock() or unlock()
    // itself to figure out which lock to lock.
    //
    // Fortunately, that doesn't matter. The only things we ask of CallLinkInfo - the slow
    // path count, the stub, and the target - can all be asked racily. Stubs and targets can
    // only be deleted at next GC, so if we load a non-null one, then it must contain data
    // that is still marginally valid (i.e. the pointers ain't stale). This kind of raciness
    // is probably OK for now.

    if (callLinkInfo.slowPathCount >= Options::couldTakeSlowCaseMinimumCount())
        return takesSlowPath();

    if (ClosureCallStubRoutine* stub = callLinkInfo.stub.get())
        return CallLinkStatus(stub->executable(), stub->structure());

    JSFunction* target = callLinkInfo.lastSeenCallee.get();
    if (!target)
        return CallLinkStatus();

    if (callLinkInfo.hasSeenClosure)
        return CallLinkStatus(target->executable(), target->structure());

    return CallLinkStatus(target);
}

void JSFunction::visitChildren(JSCell* cell, SlotVisitor& visitor)
{
    JSFunction* thisObject = jsCast<JSFunction*>(cell);
    ASSERT_GC_OBJECT_INHERITS(thisObject, &s_info);
    COMPILE_ASSERT(StructureFlags & OverridesVisitChildren, OverridesVisitChildrenWithoutSettingFlag);
    ASSERT(thisObject->structure()->typeInfo().overridesVisitChildren());
    Base::visitChildren(thisObject, visitor);

    visitor.append(&thisObject->m_scope);
    visitor.append(&thisObject->m_executable);
}

CallLinkStatus CallLinkStatus::computeFor(const ConcurrentJITLocker&, CallLinkInfo& callLinkInfo)
{
    if (callLinkInfo.slowPathCount >= Options::couldTakeSlowCaseMinimumCount())
        return takesSlowPath();
    
    if (callLinkInfo.stub)
        return CallLinkStatus(callLinkInfo.stub->executable(), callLinkInfo.stub->structure());
    
    JSFunction* target = callLinkInfo.lastSeenCallee.get();
    if (!target)
        return CallLinkStatus();
    
    if (callLinkInfo.hasSeenClosure)
        return CallLinkStatus(target->executable(), target->structure());

    return CallLinkStatus(target);
}