What's new in the Project

• June 1999: FAJITA evolves into JCOD project
• June 1998: FAJITA Alpha Release available
• January 10th, 1998: FAJITA Home Page is created

Objectives and Benefits

FAJITA stands for Footprint Aware Just-In-Time for Appliances. FAJITA is a Just-In-Time (JIT) compiler designed specifically for Java ^(TM) enabled embedded systems. It distinguishes itself from other JIT compilers available on the market in two major ways:

• It is separate from the Java runtime. It is not embedded within the Java run time. It works as a compiling server running on a network node. It compiles Java byte code as a pass-through proxy server.
• It generates native code with the high priority objective to reduce memory requirements. As a result the generated code is not reaching as high performance as our TurboJ compiler does, but it does boost performance compared to interpreted byte code by an order of magnitude. However the generated code is smaller and more appropriate for embedded systems.

In particular, the design center of the compiler has been towards 8bits or 16bits instruction sets such as found on the MIPS16 instruction set or the PSC1000 chip. Those chips offer a very dense instruction set that occupy typically 40% less memory than traditional chips and therefore offer economic interest for embedded systems manufacturers.

FAJITA Compiler

The FAJITA project is designed to develop a Java to native compiler that

• transforms Java byte codes executed by the Java interpreter to native executable code.
• retains that executable code for subsequent usage.
• allows the mix and match of both interpreted code and compiled code.

The FAJITA implementation compiles the Java byte codes for each method as they are requested by the Java run-time system. However, instead of loading them into memory for interpretation, the methods are translated into machine binary code.

FAJITA supports mix and match of interpreted code and compiled code. Users can run in the same environment intrepreted classes and compiled classes.

Any Java application which can be run in the interpreter mode by that system can also run as FAJITA compiled code. The generated code still retains all of the run-time checks required to conform to the Java semantics (e.g. array bounds checking), in order to assure that the safety model for Java is not violated. However, it looks for opportunities to remove redundant checks.

In order to be totally portable, the FAJITA compiler is written in Java (which also provides a stress test as our first test is to compile the compiler itself) and it generates native code.

Schedule and Deliverable

The FAJITA project just reached its Alpha Release in June 98. The Alpha software and specifications are is only available to project sponsors. It consists of a compiler for MIPS processors running on the VxWorks operating system.