1 research outputs found
Offline Specialisation in Prolog Using a Hand-Written Compiler Generator
The so called ``cogen approach'' to program specialisation, writing a
compiler generator instead of a specialiser, has been used with considerable
success in partial evaluation of both functional and imperative languages. This
paper demonstrates that the cogen approach is also applicable to the
specialisation of logic programs (also called partial deduction) and leads to
effective specialisers. Moreover, using good binding-time annotations, the
speed-ups of the specialised programs are comparable to the speed-ups obtained
with online specialisers. The paper first develops a generic approach to
offline partial deduction and then a specific offline partial deduction method,
leading to the offline system LIX for pure logic programs. While this is a
usable specialiser by itself, it is used to develop the cogen system LOGEN.
Given a program, a specification of what inputs will be static, and an
annotation specifying which calls should be unfolded, LOGEN generates a
specialised specialiser for the program at hand. Running this specialiser with
particular values for the static inputs results in the specialised program.
While this requires two steps instead of one, the efficiency of the
specialisation process is improved in situations where the same program is
specialised multiple times. The paper also presents and evaluates an automatic
binding-time analysis that is able to derive the annotations. While the derived
annotations are still suboptimal compared to hand-crafted ones, they enable
non-expert users to use the LOGEN system in a fully automated way. Finally,
LOGEN is extended so as to directly support a large part of Prolog's
declarative and non-declarative features and so as to be able to perform so
called mixline specialisations.Comment: 52 pages, to appear in the journal "Theory and Practice of Logic
Programming