PARTIAL TRANSLATION - TOWARDS A PORTABLE AND EFFICIENT PROLOG IMPLEMENTATION TECHNOLOGY

We describe a new language translation framework (partial translation) and the application of one of its instances: the C-ification of Binar y Prolog. Our partial translation framework compiles selected sequence s of emulator instructions down to native code. The technique can be s een as an automatic specialization. with respect to a given program of the traditional instruction folding techniques used to speed up emula tors. In our implementation, the complex control structure, some large instructions, and the management of the symbol table are left to the emulator, while the translated code deals with relatively long sequenc es of simple instructions. After compilation, the generated code is li nked with a target language representation of the emulator's byte code and the emulator itself to form a stand-alone application. The compos ite run-time system's behavior can be seen as a form of ''coroutining' ' between emulated and native code. The framework supports modular com pilation, allows programmer control of the speed versus size optimizat ion, is fully portable, and has a performance that ranges between the performance of emulated code and that of native code. Our design has b een proven practical in the implementation of the C-code generator of a fairly complete multiplatform Prolog system (BinProlog) available by ftp at clement.info.umoncton.ca.