JIT编译器如何帮助应用程序的性能？ [英] How a JIT compiler helps performance of applications?

问题描述

我只是读到 Android的性能提高了450％，因为它添加了JIT编译器，我知道JIT是什么，但我不知道为什么它比正常的编译代码更快？或与Android平台（Java类似运行编译的字节码）的旧方法有什么区别。

I just read that Android has a 450% performance improvement because it added a JIT compiler, I know what JIT is, but I don't really understand why is it faster than normal compiled code? or what's the difference with the older approach from the Android platform (the Java like run compiled bytecode).

谢谢！

编辑：这是非常有趣的，谢谢！，我希望我可以选择每个答案是正确的：）

This is hugely interesting, thanks!, I wish I could pick every answer as correct :)

推荐答案

一个免责声明，我不熟悉Android。无论如何...

First a disclaimer, I'm not at all familiar with Android. Anyway...

我熟悉的JIT编译有两个应用程序。一种是将字节代码转换成实际的机器指令。第二个是超优化。

There are two applications of JIT compilation that I am familiar with. One is to convert from byte-codes into the actual machine instructions. The second is Superoptimisation.

JIT字节码编译加速了事情，因为字节码只被插入一次，而不是每次被执行。这可能是你看到的优化类型。

JIT bytecode compilation speeds things up because the bytecodes are only interpeted once, instead of each time it is executed. This is probably the sort of optimisation you are seeing.

JIT超级选择，搜索真正最优的指令集来实现程序逻辑，有点更深奥。这可能不是你的话，虽然我已经读了100％ - 200％的速度增加的结果。

JIT superoptimsation, which searches for the truly optimal set of instructions to implement a programs logic, is a little more esoteric. It's probably not what your talking about, though I have read reports of 100% - 200% speed increases as a result.

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