Sufficiently patched, kluged, and tweaked that the surgical scars are beginning to crowd out normal tissue (compare critical mass). Not all programs that are hacked become "hacked up"; if modifications are done with some eye to coherence and continued maintainability, the software may emerge better for the experience.
Contrast hack up.
I were hacked up a leetle, but he got a big leak in him an' all of a sudden he wasn't thar.
This corral, hacked up by our supply of ice, gave us full assurances that our good luck would not be followed by reckless waste.
But if we are hacked up in soup, or starved out completely, I have my doubts of our staying powers.
If it is for a feast, it is hacked up into small pieces and loaded into earthen pots, iron pans, and bamboo joints.
Elizabeth sat down before a very old desk, much battered and hacked up with knife marks.