A Just-in-Time Compiler for Memory-Constrained Low-Power Devices

Typical just-in-time compilers for the Javaä platform are often too large and too slow to be used in small computing devices such as cell phones or PDAs. In contrast, the JIT described here was targeted for such devices, and was built on Sun Microsystem’s KVM product. Key to making the JIT effective were: a pre-compilation transformation of the bytecodes to make compilation easier; compilation of only a subset of the bytecodes to make the production of the system simpler; quick and simple management of the JIT code buffer; and an effective heap comparison technique that greatly aided debugging of generated code. The JIT speeded up execution by a factor of between 5.7 and 10.7. Its implementation required only 60KB of ARM machine code.