The gp2c compiler is a package for translating GP routines into the C
programming language, so that they can be compiled and used with the PARI system
or the GP calculator.

The main advantage of doing this is to speed up computations and to include your
own routines within the preexisting GP ones. It may also find bugs in GP
scripts.

WWW: https://pari.math.u-bordeaux.fr/pub/pari/manuals/gp2c/gp2c.html