Evolution of a Java']Java just-in-time compiler for IA-32 platforms

Java(TM) has gained widespread popularity in the industry, and an efficient Java virtual machine (JVM(TM)) and just-in-time (JIT) compiler are crucial in providing high performance for Java applications. This paper describes the design and implementation of our HT compiler for IA-32 platforms by focusing on the recent advances achieved in the past several years. We first present the dynamic optimization framework, which focuses the expensive optimization efforts only on performance-critical methods, thus helping to manage the total compilation overhead. We then describe the platform-independent features, which include the conversion from the stack-semantic Java bytecode into our register-based intermediate representation (IR) and a variety of aggressive optimizations applied to the IR. We also present some techniques specific to the IA-32 used to improve code quality, especially for the efficient use of the small number of registers on that platform. Using several industry-standard benchmark programs, the experimental results show that our approach offers high performance with low compilation overhead. Most of the techniques presented here are included in the IBM HT compiler product, integrated into the IBM Development Kit for Microsoft Windows(R), Java Technology Edition Version 1.4.0.