想问一个关于即时编译的问题

[7911364440]

Java 字节码经过即时编译之后会变成机器码，这些机器码存在哪里的，内存吗？编译后的机器码会不会失效？ 如果一段代码一开始调用频率非常高，被判定为热点代码并被即时编译，那如果这段代码之后不会再被访问，这段代码会不会降级为解释执行？

[crayygy]

https://www.ibm.com/docs/zh/sdk-java-technology/8?topic=reference-jit-compiler

[koebehshian]

For example, translation to machine code was done on demand, and the result was cached for later use. When memory became scarce, the system would delete some of this code and regenerate it when it was needed again.
--- https://en.wikipedia.org/wiki/Just-in-time_compilation#Design

是在内存，内存不够是会被替换掉。

[letianqiu]

在 code cache 里。实际上就是 CHeap 里。hotspot 里有个东西叫 deoptimization ，就是你说的降级