When you compile a Java program, the bytecode generated is optimized by a Just-In-Time compiler (JIT) at runtime in HotSpot (OpenJDK’s JVM). This optimization takes advantage of runtime conditions like hardware and specific data fed into the program. To debug the JIT’s compilation process, set up a test project to trigger compilation and use flags like -XX:CompileCommand and -Xbatch to print the assembly of compiled methods. Understanding the JIT’s operations is crucial for analyzing Java program performance. By exploring techniques like disassembling machine code and printing inlining traces, you can gain insights into JIT compilation and code optimization.
https://jornvernee.github.io/hotspot/jit/2023/08/18/debugging-jit.html