javascript - 在node.js中运行的js文件中的％GetOptimizationStatus函数是什么

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我正在阅读有关优化技术的this article，其中包含以下代码：

//Function that contains the pattern to be inspected (using an `eval` statement)
function exampleFunction() {
    return 3;
    eval('');
}

function printStatus(fn) {
    switch(%GetOptimizationStatus(fn)) {
        case 1: console.log("Function is optimized"); break;
        case 2: console.log("Function is not optimized"); break;
        case 3: console.log("Function is always optimized"); break;
        case 4: console.log("Function is never optimized"); break;
        case 6: console.log("Function is maybe deoptimized"); break;
        case 7: console.log("Function is optimized by TurboFan"); break;
        default: console.log("Unknown optimization status"); break;
    }
}

//Fill type-info
exampleFunction();
// 2 calls are needed to go from uninitialized -> pre-monomorphic -> monomorphic
exampleFunction();

%OptimizeFunctionOnNextCall(exampleFunction);
//The next call
exampleFunction();

//Check
printStatus(exampleFunction);

我有两个问题：


函数%GetOptimizationStatus和%OptimizeFunctionOnNextCall从未定义，它们从何而来？
2 calls are needed to go from uninitialized -> pre-monomorphic -> monomorphic是什么意思？

最佳答案

设置指定的优化标志时，将%GetOptimizationStatus和%OptimizeFunctionOnNextCall注入到Node中。

从根本上讲，单态部分表示优化器只有在检测到多次使用后才能启动。.在激活此TurboFan之后。

IOW：如果查看输出，您会注意到它两次调用了exampleFunction（禁用了优化），并且只有在第三次尝试时，TurboFan才会启动。