+
+#ifdef DEBUG
+ switch (get_itbl((StgClosure *)p)->type) {
+ case MUT_VAR_CLEAN:
+ barf("MUT_VAR_CLEAN on mutable list");
+ case MUT_VAR_DIRTY:
+ mutlist_MUTVARS++; break;
+ case MUT_ARR_PTRS_CLEAN:
+ case MUT_ARR_PTRS_DIRTY:
+ case MUT_ARR_PTRS_FROZEN:
+ case MUT_ARR_PTRS_FROZEN0:
+ mutlist_MUTARRS++; break;
+ default:
+ mutlist_OTHERS++; break;
+ }
+#endif
+
+ // Check whether this object is "clean", that is it
+ // definitely doesn't point into a young generation.
+ // Clean objects don't need to be scavenged. Some clean
+ // objects (MUT_VAR_CLEAN) are not kept on the mutable
+ // list at all; others, such as MUT_ARR_PTRS_CLEAN and
+ // TSO, are always on the mutable list.
+ //
+ switch (get_itbl((StgClosure *)p)->type) {
+ case MUT_ARR_PTRS_CLEAN:
+ recordMutableGen((StgClosure *)p,gen);
+ continue;
+ case TSO: {
+ StgTSO *tso = (StgTSO *)p;
+ if ((tso->flags & TSO_DIRTY) == 0) {
+ // A clean TSO: we don't have to traverse its
+ // stack. However, we *do* follow the link field:
+ // we don't want to have to mark a TSO dirty just
+ // because we put it on a different queue.
+ if (tso->why_blocked != BlockedOnBlackHole) {
+ tso->link = (StgTSO *)evacuate((StgClosure *)tso->link);
+ }
+ recordMutableGen((StgClosure *)p,gen);
+ continue;
+ }
+ }
+ default:
+ ;
+ }
+