// Adjust BOT to show that a previously whole block has been split
// into two.
void G1BlockOffsetArray::split_block(HeapWord* blk, size_t blk_size,
size_t left_blk_size) {
// Verify that the BOT shows [blk, blk + blk_size) to be one block.
verify_single_block(blk, blk_size);
// Update the BOT to indicate that [blk + left_blk_size, blk + blk_size)
// is one single block.
mark_block(blk + left_blk_size, blk + blk_size);
}
//////////////////////////////////////////////////////////////////////////
// BlockOffsetArrayNonContigSpace inlines
//////////////////////////////////////////////////////////////////////////
inline void G1BlockOffsetArray::freed(HeapWord* blk_start, HeapWord* blk_end) {
// Verify that the BOT shows [blk_start, blk_end) to be one block.
verify_single_block(blk_start, blk_end);
// adjust _unallocated_block upward or downward
// as appropriate
if (BlockOffsetArrayUseUnallocatedBlock) {
assert(_unallocated_block <= _end,
"Inconsistent value for _unallocated_block");
if (blk_end >= _unallocated_block && blk_start <= _unallocated_block) {
// CMS-specific note: a block abutting _unallocated_block to
// its left is being freed, a new block is being added or
// we are resetting following a compaction
_unallocated_block = blk_start;
}
}
}
void BlockOffsetArrayNonContigSpace::verify_single_block(
HeapWord* blk, size_t size) {
verify_single_block(blk, blk + size);
}
// Adjust BOT to show that a previously whole block has been split
// into two. We verify the BOT for the first part (prefix) and
// update the BOT for the second part (suffix).
// blk is the start of the block
// blk_size is the size of the original block
// left_blk_size is the size of the first part of the split
void BlockOffsetArrayNonContigSpace::split_block(HeapWord* blk,
size_t blk_size,
size_t left_blk_size) {
// Verify that the BOT shows [blk, blk + blk_size) to be one block.
verify_single_block(blk, blk_size);
// Update the BOT to indicate that [blk + left_blk_size, blk + blk_size)
// is one single block.
assert(blk_size > 0, "Should be positive");
assert(left_blk_size > 0, "Should be positive");
assert(left_blk_size < blk_size, "Not a split");
// Start addresses of prefix block and suffix block.
HeapWord* pref_addr = blk;
HeapWord* suff_addr = blk + left_blk_size;
HeapWord* end_addr = blk + blk_size;
// Indices for starts of prefix block and suffix block.
size_t pref_index = _array->index_for(pref_addr);
if (_array->address_for_index(pref_index) != pref_addr) {
// pref_addr does not begin pref_index
pref_index++;
}
size_t suff_index = _array->index_for(suff_addr);
if (_array->address_for_index(suff_index) != suff_addr) {
// suff_addr does not begin suff_index
suff_index++;
}
// Definition: A block B, denoted [B_start, B_end) __starts__
// a card C, denoted [C_start, C_end), where C_start and C_end
// are the heap addresses that card C covers, iff
// B_start <= C_start < B_end.
//
// We say that a card C "is started by" a block B, iff
// B "starts" C.
//
// Note that the cardinality of the set of cards {C}
// started by a block B can be 0, 1, or more.
//
// Below, pref_index and suff_index are, respectively, the
// first (least) card indices that the prefix and suffix of
// the split start; end_index is one more than the index of
// the last (greatest) card that blk starts.
size_t end_index = _array->index_for(end_addr - 1) + 1;
// Calculate the # cards that the prefix and suffix affect.
size_t num_pref_cards = suff_index - pref_index;
size_t num_suff_cards = end_index - suff_index;
// Change the cards that need changing
if (num_suff_cards > 0) {
HeapWord* boundary = _array->address_for_index(suff_index);
// Set the offset card for suffix block
_array->set_offset_array(suff_index, boundary, suff_addr, true /* reducing */);
// Change any further cards that need changing in the suffix
if (num_pref_cards > 0) {
if (num_pref_cards >= num_suff_cards) {
// Unilaterally fix all of the suffix cards: closed card
// index interval in args below.
set_remainder_to_point_to_start_incl(suff_index + 1, end_index - 1, true /* reducing */);
} else {
// Unilaterally fix the first (num_pref_cards - 1) following
// the "offset card" in the suffix block.
set_remainder_to_point_to_start_incl(suff_index + 1,
suff_index + num_pref_cards - 1, true /* reducing */);
// Fix the appropriate cards in the remainder of the
// suffix block -- these are the last num_pref_cards
// cards in each power block of the "new" range plumbed
// from suff_addr.
bool more = true;
uint i = 1;
while (more && (i < N_powers)) {
size_t back_by = power_to_cards_back(i);
size_t right_index = suff_index + back_by - 1;
size_t left_index = right_index - num_pref_cards + 1;
if (right_index >= end_index - 1) { // last iteration
right_index = end_index - 1;
more = false;
}
if (back_by > num_pref_cards) {
// Fill in the remainder of this "power block", if it
// is non-null.
if (left_index <= right_index) {
_array->set_offset_array(left_index, right_index,
N_words + i - 1, true /* reducing */);
} else {
more = false; // we are done
}
i++;
break;
}
i++;
}
while (more && (i < N_powers)) {
size_t back_by = power_to_cards_back(i);
size_t right_index = suff_index + back_by - 1;
size_t left_index = right_index - num_pref_cards + 1;
if (right_index >= end_index - 1) { // last iteration
right_index = end_index - 1;
if (left_index > right_index) {
break;
}
more = false;
}
assert(left_index <= right_index, "Error");
_array->set_offset_array(left_index, right_index, N_words + i - 1, true /* reducing */);
i++;
}
}
} // else no more cards to fix in suffix
} // else nothing needs to be done
// Verify that we did the right thing
verify_single_block(pref_addr, left_blk_size);
verify_single_block(suff_addr, blk_size - left_blk_size);
}
