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From: Mild Shock <janburse@fastmail.fm>
Newsgroups: comp.lang.prolog
Subject: Re: PIPs from the Basilisk Chamber (Was: 50 Years of Prolog Nonsense)
Date: Sat, 9 Nov 2024 15:47:59 +0100
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I can speed it up, if I use nb_setarg/3 instead
of the explicit duplicate_term/2 and nb_linkarg/3 combo.
The change is as follows:

/* Before */
sys_find2_next(T, X) :-
    C = [_|_],
    duplicate_term(T, H),
    nb_linkarg(1, C, H),
    arg(1, X, J),
    nb_linkarg(2, J, C),
    nb_linkarg(1, X, C)

/* After */
sys_find2_next(T, X) :-
    C = [_|_],
    nb_setarg(1, C, T),
    arg(1, X, J),
    nb_linkarg(2, J, C),
    nb_linkarg(1, X, C).

Now the timings are better:

/* Before */
?- time(test2).
% 6,007,999 inferences, 0.422 CPU in 0.427
seconds (99% CPU, 14241183 Lips)
true.

/* After */
?- time(test2).
% 5,007,999 inferences, 0.297 CPU in 0.298
seconds (100% CPU, 16869049 Lips)
true.

A wooping more than 100 milliseconds are gone!