void do_MemRegion(MemRegion mr) {
// We start at the high end of "mr", walking backwards
// while accumulating a contiguous dirty range of cards in
// [start_of_non_clean, end_of_non_clean) which we then
// process en masse.
HeapWord* end_of_non_clean = mr.end();
HeapWord* start_of_non_clean = end_of_non_clean;
jbyte* entry = _ct->byte_for(mr.last());
const jbyte* first_entry = _ct->byte_for(mr.start());
while (entry >= first_entry) {
HeapWord* cur = _ct->addr_for(entry);
if (!clear_card(entry)) {
// We hit a clean card; process any non-empty
// dirty range accumulated so far.
if (start_of_non_clean < end_of_non_clean) {
MemRegion mr2(start_of_non_clean, end_of_non_clean);
_dirty_card_closure->do_MemRegion(mr2);
}
// Reset the dirty window while continuing to
// look for the next dirty window to process.
end_of_non_clean = cur;
start_of_non_clean = end_of_non_clean;
}
// Open the left end of the window one card to the left.
start_of_non_clean = cur;
// Note that "entry" leads "start_of_non_clean" in
// its leftward excursion after this point
// in the loop and, when we hit the left end of "mr",
// will point off of the left end of the card-table
// for "mr".
entry--;
}
// If the first card of "mr" was dirty, we will have
// been left with a dirty window, co-initial with "mr",
// which we now process.
if (start_of_non_clean < end_of_non_clean) {
MemRegion mr2(start_of_non_clean, end_of_non_clean);
_dirty_card_closure->do_MemRegion(mr2);
}
}
void do_MemRegion(MemRegion mr) {
HeapWord* end_of_non_clean = mr.end();
HeapWord* start_of_non_clean = end_of_non_clean;
jbyte* entry = _ct->byte_for(mr.last());
HeapWord* cur = _ct->addr_for(entry);
while (mr.contains(cur)) {
jbyte entry_val = *entry;
if (!clear_card(entry)) {
if (start_of_non_clean < end_of_non_clean) {
MemRegion mr2(start_of_non_clean, end_of_non_clean);
_dirty_card_closure->do_MemRegion(mr2);
}
end_of_non_clean = cur;
start_of_non_clean = end_of_non_clean;
}
entry--;
start_of_non_clean = cur;
cur = _ct->addr_for(entry);
}
if (start_of_non_clean < end_of_non_clean) {
MemRegion mr2(start_of_non_clean, end_of_non_clean);
_dirty_card_closure->do_MemRegion(mr2);
}
}