Interesting paper on Supporting Binary Compatibility with Static Compilation

Fri Aug 9 14:01:00 GMT 2002

Hi,
The following paper seems to be a must read for gcj hackers:
http://flint.cs.yale.edu/flint/publications/bincomp.html
Supporting Binary Compatibility with Static Compilation
Dachuan Yu, Zhong Shao, Valery Trifonov
Department of Computer Science, Yale University
Below is the Abstract, Conclusion and Acknowledgments.
I believe this describes what Bryce calls "the grand binary
compatibility plan".
Cheers,
Mark
 Abstract

 There is an ongoing debate in the Java community on
 whether statically compiled implementations can meet
 the Java specification on dynamic features such as binary
 compatibility. Static compilation is sometimes desirable
 because it provides better code optimization, smaller
 memory footprint, more robustness, and better intellec-
 tual property protection. Unfortunately, none of the ex-
 isting static Java compilers support binary compatibility,
 because it incurs unacceptable performance overhead.
 In this paper, we propose a simple yet effective solu-
 tion which handles all of the binary-compatibility cases
 specified by the Java Language Specification. Our ex-
 perimental results using an implementation in the GNU
 Java compiler shows that the performance penalty is on
 average less than 2%. Besides solving the problem for
 static compilers, it is also possible to use this technique
 in JIT compilers to achieve an optimal balance point be-
 tween static and dynamic compilation.
 Conclusion

 We have presented a scheme which uses static compi-
 lation to support Java binary compatibility. All of the
 binary compatibility requirements in the Java Language
 Specification are supported with the same set of sim-
 ple techniques. Binaries changed in a compatible man-
 ner can link successfully with pre-existing binaries that
 previously linked without error. Incompatible changes
 raise various run-time exceptions accordingly. Our im-
 plementation shows that this approach is fairly efficient
 and has the potential of being applied to real systems.

 Acknowledgments

 We want to specially thank Bryce McKinlay for imple-
 menting the indirect dispatching scheme for GCJ and his
 inspiring discussion on related issues, and Manish Gupta
 for keeping us informed about the state-of-the-art in dy-
 namic Java compilers. We also thank many posters on
 the GCJ mailing list (java@gcc.gnu.org) for answering
 our questions about the GCJ internals, Greg Collins and
 Andrew McCreight for valuable comments on an early
 version of our paper, and the anonymous reviewers.