*obj_slot = forwarded;
#ifndef SGEN_SIMPLE_NURSERY
if (G_UNLIKELY (sgen_ptr_in_nursery (forwarded) && !sgen_ptr_in_nursery (obj_slot)))
- sgen_add_to_global_remset (obj_slot);
+ sgen_add_to_global_remset (obj_slot, forwarded);
#endif
return;
}
SGEN_LOG (9, " (pinned, no change)");
HEAVY_STAT (++stat_nursery_copy_object_failed_pinned);
if (!sgen_ptr_in_nursery (obj_slot))
- sgen_add_to_global_remset (obj_slot);
+ sgen_add_to_global_remset (obj_slot, obj);
return;
}
SGEN_ASSERT (9, ((MonoVTable*)SGEN_LOAD_VTABLE(obj))->gc_descr, "to space object %p has no gc descriptor", obj);
SGEN_LOG (9, " (tospace, no change)");
HEAVY_STAT (++stat_nursery_copy_object_failed_to_space);
+
+ /*
+ * FIXME:
+ *
+ * The card table scanning code sometimes clears cards
+ * that have just been set for a global remset. In
+ * the split nursery the following situation can
+ * occur:
+ *
+ * Let's say object A starts in card C but continues
+ * into C+1. Within A, at offset O there's a
+ * reference to a new nursery object X. A+O is in
+ * card C+1. Now card C is scanned, and as part of
+ * it, object A. The reference at A+O is processed by
+ * copying X into nursery to-space at Y. Since it's
+ * still in the nursery, a global remset must be added
+ * for A+O, so card C+1 is marked. Now, however, card
+ * C+1 is scanned, which means that it's cleared
+ * first. This wouldn't be terribly bad if reference
+ * A+O were re-scanned and the global remset re-added,
+ * but since the reference points to to-space, that
+ * doesn't happen, and C+1 remains cleared: the remset
+ * is lost.
+ *
+ * There's at least two ways to fix this. The easy
+ * one is to re-add the remset on the re-scan. This
+ * is that - the following two lines of code.
+ *
+ * The proper solution appears to be to first make a
+ * copy of the cards before scanning a block, then to
+ * clear all the cards and scan from the copy, so no
+ * remsets will be overwritten. Scanning objects at
+ * most once would be the icing on the cake.
+ */
+ if (!sgen_ptr_in_nursery (obj_slot))
+ sgen_add_to_global_remset (obj_slot, obj);
+
return;
}
#endif
*obj_slot = copy;
#ifndef SGEN_SIMPLE_NURSERY
if (G_UNLIKELY (sgen_ptr_in_nursery (copy) && !sgen_ptr_in_nursery (obj_slot)))
- sgen_add_to_global_remset (obj_slot);
+ sgen_add_to_global_remset (obj_slot, copy);
#else
/* copy_object_no_checks () can return obj on OOM */
if (G_UNLIKELY (obj == copy)) {
if (G_UNLIKELY (sgen_ptr_in_nursery (copy) && !sgen_ptr_in_nursery (obj_slot)))
- sgen_add_to_global_remset (obj_slot);
+ sgen_add_to_global_remset (obj_slot, copy);
}
#endif
}
objsize = SGEN_ALIGN_UP (sgen_par_object_get_size (vt, (MonoObject*)obj));
has_references = SGEN_VTABLE_HAS_REFERENCES (vt);
- destination = COLLECTOR_PARALLEL_ALLOC_FOR_PROMOTION (obj, objsize, has_references);
+ destination = COLLECTOR_PARALLEL_ALLOC_FOR_PROMOTION (vt, obj, objsize, has_references);
if (G_UNLIKELY (!destination)) {
sgen_parallel_pin_or_update (obj_slot, obj, vt, queue);