A Retargetable Optimizing Java-to-C Compiler for Embedded Systems

Ankush Varma

Master's Report,
Department of Electrical and Computer Engineering, University of Maryland, College Park, MD
2003

ABSTRACT

The Java programming language is achieving greater acceptance in high-end embedded systems such as cellphones and PDAs. However, lowend embedded platforms, such as DSPs or microcontrollers, often have no more than a C compiler, and this prevents Java applications from being run on such systems. Applications must either be re-written in C, or a Java Virtual Machine must be ported to each such system.

This paper discusses a compiler that converts portable Java bytecode to C code, allowing applications written in Java to run on embedded systems which may lack a Java Virtual Machine. This is also applicable to barebones embedded systems running without an operating system. We briefly describe code generation strategies, run-time data structures and optimization algorithms used to generate efficient C code. The code size and execution time of the C code were compared with interpreted Java, just-in-time compiled Java, and executables generated directly from Java.

On an average, we found the size of the generated stand-alone executable to be over 25 times smaller than that generated by a cutting-edge Javato- native-code compiler, while providing performance comparable to the best of various Java implementation strategies.