"Merging %d and %d because it is possible\n", s1, s2));
if(merge_interferences(env, interferences, spillslot_unionfind, s1, s2) != 0) {
"Merging %d and %d because it is possible\n", s1, s2));
if(merge_interferences(env, interferences, spillslot_unionfind, s1, s2) != 0) {