// clean (by dirty->clean before) ==> cur_younger_gen
// dirty ==> cur_youngergen_and_prev_nonclean_card
// precleaned ==> cur_youngergen_and_prev_nonclean_card
// prev-younger-gen ==> cur_youngergen_and_prev_nonclean_card
// cur-younger-gen ==> cur_younger_gen
// cur_youngergen_and_prev_nonclean_card ==> no change.
void CardTableRS::write_ref_field_gc_par(void* field, oop new_val) {
jbyte* entry = ct_bs()->byte_for(field);
do {
jbyte entry_val = *entry;
// We put this first because it's probably the most common case.
if (entry_val == clean_card_val()) {
// No threat of contention with cleaning threads.
*entry = cur_youngergen_card_val();
return;
} else if (card_is_dirty_wrt_gen_iter(entry_val)
|| is_prev_youngergen_card_val(entry_val)) {
// Mark it as both cur and prev youngergen; card cleaning thread will
// eventually remove the previous stuff.
jbyte new_val = cur_youngergen_and_prev_nonclean_card;
jbyte res = Atomic::cmpxchg(new_val, entry, entry_val);
// Did the CAS succeed?
if (res == entry_val) return;
// Otherwise, retry, to see the new value.
continue;
} else {
assert(entry_val == cur_youngergen_and_prev_nonclean_card
|| entry_val == cur_youngergen_card_val(),
"should be only possibilities.");
return;
}
} while (true);
}
// Returns "true" iff the value "cv" may have represented a dirty card at
// some point.
virtual bool card_may_have_been_dirty(jbyte cv) {
return card_is_dirty_wrt_gen_iter(cv);
}
bool CardTableModRefBSForCTRS::card_may_have_been_dirty(jbyte cv) {
return
cv != clean_card &&
(card_is_dirty_wrt_gen_iter(cv) ||
CardTableRS::youngergen_may_have_been_dirty(cv));
}
bool CardTableModRefBSForCTRS::card_will_be_scanned(jbyte cv) {
return
card_is_dirty_wrt_gen_iter(cv) ||
_rs->is_prev_nonclean_card_val(cv);
}
