Array Bytecode Support in MicroJIT

Eclipse OpenJ9 is a Java virtual machine (JVM), which initially interprets Java programs. OpenJ9 uses Just-in-Time (JIT) compilers—like the default Testarossa JIT (TRJIT)—to translate the bytecodes of the Java program into native code, which executes faster than interpreting. TRJIT is an optimizing compiler, which boosts an application’s long-term performance but can increase start-up time due to initial compiling. Despite this overhead, more often than not, start-up time is still improved when compared to an interpreter-only solution. MicroJIT aims to reduce this initial slowdown, making start-up time even quicker. MicroJIT is a non-optim­izing, template-based compiler, which aims to reduce compilation overhead and start-up time. Array bytecodes were not supported in the initial implementation of MicroJIT, forcing them to either be interpreted or compiled using TRJIT. This work implements array bytecodes such as, newarray, aaload, aastore , in MicroJIT and measures their impact on execution of the programs. The implementation is tested with a regression test suite and the experiments are performed on the DaCapo benchmark suite. The results show that TRJIT along with MicroJIT including array bytecodes support is approximately 4.36x faster than the interpreter and 1.02x faster than the MicroJIT without array bytecodes support. These findings highlight the potential of MicroJIT in improving the performance of Java programs by efficiently handling array bytecodes.