| /* |
| * Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "gc_interface/collectedHeap.inline.hpp" |
| #include "memory/blockOffsetTable.inline.hpp" |
| #include "memory/iterator.hpp" |
| #include "memory/space.inline.hpp" |
| #include "memory/universe.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/java.hpp" |
| #include "services/memTracker.hpp" |
| |
| ////////////////////////////////////////////////////////////////////// |
| // BlockOffsetSharedArray |
| ////////////////////////////////////////////////////////////////////// |
| |
| BlockOffsetSharedArray::BlockOffsetSharedArray(MemRegion reserved, |
| size_t init_word_size): |
| _reserved(reserved), _end(NULL) |
| { |
| size_t size = compute_size(reserved.word_size()); |
| ReservedSpace rs(size); |
| if (!rs.is_reserved()) { |
| vm_exit_during_initialization("Could not reserve enough space for heap offset array"); |
| } |
| |
| MemTracker::record_virtual_memory_type((address)rs.base(), mtGC); |
| |
| if (!_vs.initialize(rs, 0)) { |
| vm_exit_during_initialization("Could not reserve enough space for heap offset array"); |
| } |
| _offset_array = (u_char*)_vs.low_boundary(); |
| resize(init_word_size); |
| if (TraceBlockOffsetTable) { |
| gclog_or_tty->print_cr("BlockOffsetSharedArray::BlockOffsetSharedArray: "); |
| gclog_or_tty->print_cr(" " |
| " rs.base(): " INTPTR_FORMAT |
| " rs.size(): " INTPTR_FORMAT |
| " rs end(): " INTPTR_FORMAT, |
| p2i(rs.base()), rs.size(), p2i(rs.base() + rs.size())); |
| gclog_or_tty->print_cr(" " |
| " _vs.low_boundary(): " INTPTR_FORMAT |
| " _vs.high_boundary(): " INTPTR_FORMAT, |
| p2i(_vs.low_boundary()), |
| p2i(_vs.high_boundary())); |
| } |
| } |
| |
| void BlockOffsetSharedArray::resize(size_t new_word_size) { |
| assert(new_word_size <= _reserved.word_size(), "Resize larger than reserved"); |
| size_t new_size = compute_size(new_word_size); |
| size_t old_size = _vs.committed_size(); |
| size_t delta; |
| char* high = _vs.high(); |
| _end = _reserved.start() + new_word_size; |
| if (new_size > old_size) { |
| delta = ReservedSpace::page_align_size_up(new_size - old_size); |
| assert(delta > 0, "just checking"); |
| if (!_vs.expand_by(delta)) { |
| // Do better than this for Merlin |
| vm_exit_out_of_memory(delta, OOM_MMAP_ERROR, "offset table expansion"); |
| } |
| assert(_vs.high() == high + delta, "invalid expansion"); |
| } else { |
| delta = ReservedSpace::page_align_size_down(old_size - new_size); |
| if (delta == 0) return; |
| _vs.shrink_by(delta); |
| assert(_vs.high() == high - delta, "invalid expansion"); |
| } |
| } |
| |
| bool BlockOffsetSharedArray::is_card_boundary(HeapWord* p) const { |
| assert(p >= _reserved.start(), "just checking"); |
| size_t delta = pointer_delta(p, _reserved.start()); |
| return (delta & right_n_bits(LogN_words)) == (size_t)NoBits; |
| } |
| |
| |
| ////////////////////////////////////////////////////////////////////// |
| // BlockOffsetArray |
| ////////////////////////////////////////////////////////////////////// |
| |
| BlockOffsetArray::BlockOffsetArray(BlockOffsetSharedArray* array, |
| MemRegion mr, bool init_to_zero_) : |
| BlockOffsetTable(mr.start(), mr.end()), |
| _array(array) |
| { |
| assert(_bottom <= _end, "arguments out of order"); |
| set_init_to_zero(init_to_zero_); |
| if (!init_to_zero_) { |
| // initialize cards to point back to mr.start() |
| set_remainder_to_point_to_start(mr.start() + N_words, mr.end()); |
| _array->set_offset_array(0, 0); // set first card to 0 |
| } |
| } |
| |
| |
| // The arguments follow the normal convention of denoting |
| // a right-open interval: [start, end) |
| void |
| BlockOffsetArray:: |
| set_remainder_to_point_to_start(HeapWord* start, HeapWord* end, bool reducing) { |
| |
| check_reducing_assertion(reducing); |
| if (start >= end) { |
| // The start address is equal to the end address (or to |
| // the right of the end address) so there are not cards |
| // that need to be updated.. |
| return; |
| } |
| |
| // Write the backskip value for each region. |
| // |
| // offset |
| // card 2nd 3rd |
| // | +- 1st | | |
| // v v v v |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+- |
| // |x|0|0|0|0|0|0|0|1|1|1|1|1|1| ... |1|1|1|1|2|2|2|2|2|2| ... |
| // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+- |
| // 11 19 75 |
| // 12 |
| // |
| // offset card is the card that points to the start of an object |
| // x - offset value of offset card |
| // 1st - start of first logarithmic region |
| // 0 corresponds to logarithmic value N_words + 0 and 2**(3 * 0) = 1 |
| // 2nd - start of second logarithmic region |
| // 1 corresponds to logarithmic value N_words + 1 and 2**(3 * 1) = 8 |
| // 3rd - start of third logarithmic region |
| // 2 corresponds to logarithmic value N_words + 2 and 2**(3 * 2) = 64 |
| // |
| // integer below the block offset entry is an example of |
| // the index of the entry |
| // |
| // Given an address, |
| // Find the index for the address |
| // Find the block offset table entry |
| // Convert the entry to a back slide |
| // (e.g., with today's, offset = 0x81 => |
| // back slip = 2**(3*(0x81 - N_words)) = 2**3) = 8 |
| // Move back N (e.g., 8) entries and repeat with the |
| // value of the new entry |
| // |
| size_t start_card = _array->index_for(start); |
| size_t end_card = _array->index_for(end-1); |
| assert(start ==_array->address_for_index(start_card), "Precondition"); |
| assert(end ==_array->address_for_index(end_card)+N_words, "Precondition"); |
| set_remainder_to_point_to_start_incl(start_card, end_card, reducing); // closed interval |
| } |
| |
| |
| // Unlike the normal convention in this code, the argument here denotes |
| // a closed, inclusive interval: [start_card, end_card], cf set_remainder_to_point_to_start() |
| // above. |
| void |
| BlockOffsetArray::set_remainder_to_point_to_start_incl(size_t start_card, size_t end_card, bool reducing) { |
| |
| check_reducing_assertion(reducing); |
| if (start_card > end_card) { |
| return; |
| } |
| assert(start_card > _array->index_for(_bottom), "Cannot be first card"); |
| assert(_array->offset_array(start_card-1) <= N_words, |
| "Offset card has an unexpected value"); |
| size_t start_card_for_region = start_card; |
| u_char offset = max_jubyte; |
| for (int i = 0; i < N_powers; i++) { |
| // -1 so that the the card with the actual offset is counted. Another -1 |
| // so that the reach ends in this region and not at the start |
| // of the next. |
| size_t reach = start_card - 1 + (power_to_cards_back(i+1) - 1); |
| offset = N_words + i; |
| if (reach >= end_card) { |
| _array->set_offset_array(start_card_for_region, end_card, offset, reducing); |
| start_card_for_region = reach + 1; |
| break; |
| } |
| _array->set_offset_array(start_card_for_region, reach, offset, reducing); |
| start_card_for_region = reach + 1; |
| } |
| assert(start_card_for_region > end_card, "Sanity check"); |
| DEBUG_ONLY(check_all_cards(start_card, end_card);) |
| } |
| |
| // The card-interval [start_card, end_card] is a closed interval; this |
| // is an expensive check -- use with care and only under protection of |
| // suitable flag. |
| void BlockOffsetArray::check_all_cards(size_t start_card, size_t end_card) const { |
| |
| if (end_card < start_card) { |
| return; |
| } |
| guarantee(_array->offset_array(start_card) == N_words, "Wrong value in second card"); |
| u_char last_entry = N_words; |
| for (size_t c = start_card + 1; c <= end_card; c++ /* yeah! */) { |
| u_char entry = _array->offset_array(c); |
| guarantee(entry >= last_entry, "Monotonicity"); |
| if (c - start_card > power_to_cards_back(1)) { |
| guarantee(entry > N_words, "Should be in logarithmic region"); |
| } |
| size_t backskip = entry_to_cards_back(entry); |
| size_t landing_card = c - backskip; |
| guarantee(landing_card >= (start_card - 1), "Inv"); |
| if (landing_card >= start_card) { |
| guarantee(_array->offset_array(landing_card) <= entry, "Monotonicity"); |
| } else { |
| guarantee(landing_card == (start_card - 1), "Tautology"); |
| // Note that N_words is the maximum offset value |
| guarantee(_array->offset_array(landing_card) <= N_words, "Offset value"); |
| } |
| last_entry = entry; // remember for monotonicity test |
| } |
| } |
| |
| |
| void |
| BlockOffsetArray::alloc_block(HeapWord* blk_start, HeapWord* blk_end) { |
| assert(blk_start != NULL && blk_end > blk_start, |
| "phantom block"); |
| single_block(blk_start, blk_end); |
| } |
| |
| // Action_mark - update the BOT for the block [blk_start, blk_end). |
| // Current typical use is for splitting a block. |
| // Action_single - udpate the BOT for an allocation. |
| // Action_verify - BOT verification. |
| void |
| BlockOffsetArray::do_block_internal(HeapWord* blk_start, |
| HeapWord* blk_end, |
| Action action, bool reducing) { |
| assert(Universe::heap()->is_in_reserved(blk_start), |
| "reference must be into the heap"); |
| assert(Universe::heap()->is_in_reserved(blk_end-1), |
| "limit must be within the heap"); |
| // This is optimized to make the test fast, assuming we only rarely |
| // cross boundaries. |
| uintptr_t end_ui = (uintptr_t)(blk_end - 1); |
| uintptr_t start_ui = (uintptr_t)blk_start; |
| // Calculate the last card boundary preceding end of blk |
| intptr_t boundary_before_end = (intptr_t)end_ui; |
| clear_bits(boundary_before_end, right_n_bits(LogN)); |
| if (start_ui <= (uintptr_t)boundary_before_end) { |
| // blk starts at or crosses a boundary |
| // Calculate index of card on which blk begins |
| size_t start_index = _array->index_for(blk_start); |
| // Index of card on which blk ends |
| size_t end_index = _array->index_for(blk_end - 1); |
| // Start address of card on which blk begins |
| HeapWord* boundary = _array->address_for_index(start_index); |
| assert(boundary <= blk_start, "blk should start at or after boundary"); |
| if (blk_start != boundary) { |
| // blk starts strictly after boundary |
| // adjust card boundary and start_index forward to next card |
| boundary += N_words; |
| start_index++; |
| } |
| assert(start_index <= end_index, "monotonicity of index_for()"); |
| assert(boundary <= (HeapWord*)boundary_before_end, "tautology"); |
| switch (action) { |
| case Action_mark: { |
| if (init_to_zero()) { |
| _array->set_offset_array(start_index, boundary, blk_start, reducing); |
| break; |
| } // Else fall through to the next case |
| } |
| case Action_single: { |
| _array->set_offset_array(start_index, boundary, blk_start, reducing); |
| // We have finished marking the "offset card". We need to now |
| // mark the subsequent cards that this blk spans. |
| if (start_index < end_index) { |
| HeapWord* rem_st = _array->address_for_index(start_index) + N_words; |
| HeapWord* rem_end = _array->address_for_index(end_index) + N_words; |
| set_remainder_to_point_to_start(rem_st, rem_end, reducing); |
| } |
| break; |
| } |
| case Action_check: { |
| _array->check_offset_array(start_index, boundary, blk_start); |
| // We have finished checking the "offset card". We need to now |
| // check the subsequent cards that this blk spans. |
| check_all_cards(start_index + 1, end_index); |
| break; |
| } |
| default: |
| ShouldNotReachHere(); |
| } |
| } |
| } |
| |
| // The range [blk_start, blk_end) represents a single contiguous block |
| // of storage; modify the block offset table to represent this |
| // information; Right-open interval: [blk_start, blk_end) |
| // NOTE: this method does _not_ adjust _unallocated_block. |
| void |
| BlockOffsetArray::single_block(HeapWord* blk_start, |
| HeapWord* blk_end) { |
| do_block_internal(blk_start, blk_end, Action_single); |
| } |
| |
| void BlockOffsetArray::verify() const { |
| // For each entry in the block offset table, verify that |
| // the entry correctly finds the start of an object at the |
| // first address covered by the block or to the left of that |
| // first address. |
| |
| size_t next_index = 1; |
| size_t last_index = last_active_index(); |
| |
| // Use for debugging. Initialize to NULL to distinguish the |
| // first iteration through the while loop. |
| HeapWord* last_p = NULL; |
| HeapWord* last_start = NULL; |
| oop last_o = NULL; |
| |
| while (next_index <= last_index) { |
| // Use an address past the start of the address for |
| // the entry. |
| HeapWord* p = _array->address_for_index(next_index) + 1; |
| if (p >= _end) { |
| // That's all of the allocated block table. |
| return; |
| } |
| // block_start() asserts that start <= p. |
| HeapWord* start = block_start(p); |
| // First check if the start is an allocated block and only |
| // then if it is a valid object. |
| oop o = oop(start); |
| assert(!Universe::is_fully_initialized() || |
| _sp->is_free_block(start) || |
| o->is_oop_or_null(), "Bad object was found"); |
| next_index++; |
| last_p = p; |
| last_start = start; |
| last_o = o; |
| } |
| } |
| |
| ////////////////////////////////////////////////////////////////////// |
| // BlockOffsetArrayNonContigSpace |
| ////////////////////////////////////////////////////////////////////// |
| |
| // The block [blk_start, blk_end) has been allocated; |
| // adjust the block offset table to represent this information; |
| // NOTE: Clients of BlockOffsetArrayNonContigSpace: consider using |
| // the somewhat more lightweight split_block() or |
| // (when init_to_zero()) mark_block() wherever possible. |
| // right-open interval: [blk_start, blk_end) |
| void |
| BlockOffsetArrayNonContigSpace::alloc_block(HeapWord* blk_start, |
| HeapWord* blk_end) { |
| assert(blk_start != NULL && blk_end > blk_start, |
| "phantom block"); |
| single_block(blk_start, blk_end); |
| allocated(blk_start, blk_end); |
| } |
| |
| // 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); |
| } |
| |
| |
| // Mark the BOT such that if [blk_start, blk_end) straddles a card |
| // boundary, the card following the first such boundary is marked |
| // with the appropriate offset. |
| // NOTE: this method does _not_ adjust _unallocated_block or |
| // any cards subsequent to the first one. |
| void |
| BlockOffsetArrayNonContigSpace::mark_block(HeapWord* blk_start, |
| HeapWord* blk_end, bool reducing) { |
| do_block_internal(blk_start, blk_end, Action_mark, reducing); |
| } |
| |
| HeapWord* BlockOffsetArrayNonContigSpace::block_start_unsafe( |
| const void* addr) const { |
| assert(_array->offset_array(0) == 0, "objects can't cross covered areas"); |
| assert(_bottom <= addr && addr < _end, |
| "addr must be covered by this Array"); |
| // Must read this exactly once because it can be modified by parallel |
| // allocation. |
| HeapWord* ub = _unallocated_block; |
| if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) { |
| assert(ub < _end, "tautology (see above)"); |
| return ub; |
| } |
| |
| // Otherwise, find the block start using the table. |
| size_t index = _array->index_for(addr); |
| HeapWord* q = _array->address_for_index(index); |
| |
| uint offset = _array->offset_array(index); // Extend u_char to uint. |
| while (offset >= N_words) { |
| // The excess of the offset from N_words indicates a power of Base |
| // to go back by. |
| size_t n_cards_back = entry_to_cards_back(offset); |
| q -= (N_words * n_cards_back); |
| assert(q >= _sp->bottom(), |
| err_msg("q = " PTR_FORMAT " crossed below bottom = " PTR_FORMAT, |
| p2i(q), p2i(_sp->bottom()))); |
| assert(q < _sp->end(), |
| err_msg("q = " PTR_FORMAT " crossed above end = " PTR_FORMAT, |
| p2i(q), p2i(_sp->end()))); |
| index -= n_cards_back; |
| offset = _array->offset_array(index); |
| } |
| assert(offset < N_words, "offset too large"); |
| index--; |
| q -= offset; |
| assert(q >= _sp->bottom(), |
| err_msg("q = " PTR_FORMAT " crossed below bottom = " PTR_FORMAT, |
| p2i(q), p2i(_sp->bottom()))); |
| assert(q < _sp->end(), |
| err_msg("q = " PTR_FORMAT " crossed above end = " PTR_FORMAT, |
| p2i(q), p2i(_sp->end()))); |
| HeapWord* n = q; |
| |
| while (n <= addr) { |
| debug_only(HeapWord* last = q); // for debugging |
| q = n; |
| n += _sp->block_size(n); |
| assert(n > q, |
| err_msg("Looping at n = " PTR_FORMAT " with last = " PTR_FORMAT"," |
| " while querying blk_start(" PTR_FORMAT ")" |
| " on _sp = [" PTR_FORMAT "," PTR_FORMAT ")", |
| p2i(n), p2i(last), p2i(addr), p2i(_sp->bottom()), p2i(_sp->end()))); |
| } |
| assert(q <= addr, |
| err_msg("wrong order for current (" INTPTR_FORMAT ")" " <= arg (" INTPTR_FORMAT ")", |
| p2i(q), p2i(addr))); |
| assert(addr <= n, |
| err_msg("wrong order for arg (" INTPTR_FORMAT ") <= next (" INTPTR_FORMAT ")", |
| p2i(addr), p2i(n))); |
| return q; |
| } |
| |
| HeapWord* BlockOffsetArrayNonContigSpace::block_start_careful( |
| const void* addr) const { |
| assert(_array->offset_array(0) == 0, "objects can't cross covered areas"); |
| |
| assert(_bottom <= addr && addr < _end, |
| "addr must be covered by this Array"); |
| // Must read this exactly once because it can be modified by parallel |
| // allocation. |
| HeapWord* ub = _unallocated_block; |
| if (BlockOffsetArrayUseUnallocatedBlock && addr >= ub) { |
| assert(ub < _end, "tautology (see above)"); |
| return ub; |
| } |
| |
| // Otherwise, find the block start using the table, but taking |
| // care (cf block_start_unsafe() above) not to parse any objects/blocks |
| // on the cards themsleves. |
| size_t index = _array->index_for(addr); |
| assert(_array->address_for_index(index) == addr, |
| "arg should be start of card"); |
| |
| HeapWord* q = (HeapWord*)addr; |
| uint offset; |
| do { |
| offset = _array->offset_array(index); |
| if (offset < N_words) { |
| q -= offset; |
| } else { |
| size_t n_cards_back = entry_to_cards_back(offset); |
| q -= (n_cards_back * N_words); |
| index -= n_cards_back; |
| } |
| } while (offset >= N_words); |
| assert(q <= addr, "block start should be to left of arg"); |
| return q; |
| } |
| |
| #ifndef PRODUCT |
| // Verification & debugging - ensure that the offset table reflects the fact |
| // that the block [blk_start, blk_end) or [blk, blk + size) is a |
| // single block of storage. NOTE: can't const this because of |
| // call to non-const do_block_internal() below. |
| void BlockOffsetArrayNonContigSpace::verify_single_block( |
| HeapWord* blk_start, HeapWord* blk_end) { |
| if (VerifyBlockOffsetArray) { |
| do_block_internal(blk_start, blk_end, Action_check); |
| } |
| } |
| |
| void BlockOffsetArrayNonContigSpace::verify_single_block( |
| HeapWord* blk, size_t size) { |
| verify_single_block(blk, blk + size); |
| } |
| |
| // Verify that the given block is before _unallocated_block |
| void BlockOffsetArrayNonContigSpace::verify_not_unallocated( |
| HeapWord* blk_start, HeapWord* blk_end) const { |
| if (BlockOffsetArrayUseUnallocatedBlock) { |
| assert(blk_start < blk_end, "Block inconsistency?"); |
| assert(blk_end <= _unallocated_block, "_unallocated_block problem"); |
| } |
| } |
| |
| void BlockOffsetArrayNonContigSpace::verify_not_unallocated( |
| HeapWord* blk, size_t size) const { |
| verify_not_unallocated(blk, blk + size); |
| } |
| #endif // PRODUCT |
| |
| size_t BlockOffsetArrayNonContigSpace::last_active_index() const { |
| if (_unallocated_block == _bottom) { |
| return 0; |
| } else { |
| return _array->index_for(_unallocated_block - 1); |
| } |
| } |
| |
| ////////////////////////////////////////////////////////////////////// |
| // BlockOffsetArrayContigSpace |
| ////////////////////////////////////////////////////////////////////// |
| |
| HeapWord* BlockOffsetArrayContigSpace::block_start_unsafe(const void* addr) const { |
| assert(_array->offset_array(0) == 0, "objects can't cross covered areas"); |
| |
| // Otherwise, find the block start using the table. |
| assert(_bottom <= addr && addr < _end, |
| "addr must be covered by this Array"); |
| size_t index = _array->index_for(addr); |
| // We must make sure that the offset table entry we use is valid. If |
| // "addr" is past the end, start at the last known one and go forward. |
| index = MIN2(index, _next_offset_index-1); |
| HeapWord* q = _array->address_for_index(index); |
| |
| uint offset = _array->offset_array(index); // Extend u_char to uint. |
| while (offset > N_words) { |
| // The excess of the offset from N_words indicates a power of Base |
| // to go back by. |
| size_t n_cards_back = entry_to_cards_back(offset); |
| q -= (N_words * n_cards_back); |
| assert(q >= _sp->bottom(), "Went below bottom!"); |
| index -= n_cards_back; |
| offset = _array->offset_array(index); |
| } |
| while (offset == N_words) { |
| assert(q >= _sp->bottom(), "Went below bottom!"); |
| q -= N_words; |
| index--; |
| offset = _array->offset_array(index); |
| } |
| assert(offset < N_words, "offset too large"); |
| q -= offset; |
| HeapWord* n = q; |
| |
| while (n <= addr) { |
| debug_only(HeapWord* last = q); // for debugging |
| q = n; |
| n += _sp->block_size(n); |
| } |
| assert(q <= addr, "wrong order for current and arg"); |
| assert(addr <= n, "wrong order for arg and next"); |
| return q; |
| } |
| |
| // |
| // _next_offset_threshold |
| // | _next_offset_index |
| // v v |
| // +-------+-------+-------+-------+-------+ |
| // | i-1 | i | i+1 | i+2 | i+3 | |
| // +-------+-------+-------+-------+-------+ |
| // ( ^ ] |
| // block-start |
| // |
| |
| void BlockOffsetArrayContigSpace::alloc_block_work(HeapWord* blk_start, |
| HeapWord* blk_end) { |
| assert(blk_start != NULL && blk_end > blk_start, |
| "phantom block"); |
| assert(blk_end > _next_offset_threshold, |
| "should be past threshold"); |
| assert(blk_start <= _next_offset_threshold, |
| "blk_start should be at or before threshold"); |
| assert(pointer_delta(_next_offset_threshold, blk_start) <= N_words, |
| "offset should be <= BlockOffsetSharedArray::N"); |
| assert(Universe::heap()->is_in_reserved(blk_start), |
| "reference must be into the heap"); |
| assert(Universe::heap()->is_in_reserved(blk_end-1), |
| "limit must be within the heap"); |
| assert(_next_offset_threshold == |
| _array->_reserved.start() + _next_offset_index*N_words, |
| "index must agree with threshold"); |
| |
| debug_only(size_t orig_next_offset_index = _next_offset_index;) |
| |
| // Mark the card that holds the offset into the block. Note |
| // that _next_offset_index and _next_offset_threshold are not |
| // updated until the end of this method. |
| _array->set_offset_array(_next_offset_index, |
| _next_offset_threshold, |
| blk_start); |
| |
| // We need to now mark the subsequent cards that this blk spans. |
| |
| // Index of card on which blk ends. |
| size_t end_index = _array->index_for(blk_end - 1); |
| |
| // Are there more cards left to be updated? |
| if (_next_offset_index + 1 <= end_index) { |
| HeapWord* rem_st = _array->address_for_index(_next_offset_index + 1); |
| // Calculate rem_end this way because end_index |
| // may be the last valid index in the covered region. |
| HeapWord* rem_end = _array->address_for_index(end_index) + N_words; |
| set_remainder_to_point_to_start(rem_st, rem_end); |
| } |
| |
| // _next_offset_index and _next_offset_threshold updated here. |
| _next_offset_index = end_index + 1; |
| // Calculate _next_offset_threshold this way because end_index |
| // may be the last valid index in the covered region. |
| _next_offset_threshold = _array->address_for_index(end_index) + N_words; |
| assert(_next_offset_threshold >= blk_end, "Incorrect offset threshold"); |
| |
| #ifdef ASSERT |
| // The offset can be 0 if the block starts on a boundary. That |
| // is checked by an assertion above. |
| size_t start_index = _array->index_for(blk_start); |
| HeapWord* boundary = _array->address_for_index(start_index); |
| assert((_array->offset_array(orig_next_offset_index) == 0 && |
| blk_start == boundary) || |
| (_array->offset_array(orig_next_offset_index) > 0 && |
| _array->offset_array(orig_next_offset_index) <= N_words), |
| "offset array should have been set"); |
| for (size_t j = orig_next_offset_index + 1; j <= end_index; j++) { |
| assert(_array->offset_array(j) > 0 && |
| _array->offset_array(j) <= (u_char) (N_words+N_powers-1), |
| "offset array should have been set"); |
| } |
| #endif |
| } |
| |
| HeapWord* BlockOffsetArrayContigSpace::initialize_threshold() { |
| assert(!Universe::heap()->is_in_reserved(_array->_offset_array), |
| "just checking"); |
| _next_offset_index = _array->index_for(_bottom); |
| _next_offset_index++; |
| _next_offset_threshold = |
| _array->address_for_index(_next_offset_index); |
| return _next_offset_threshold; |
| } |
| |
| void BlockOffsetArrayContigSpace::zero_bottom_entry() { |
| assert(!Universe::heap()->is_in_reserved(_array->_offset_array), |
| "just checking"); |
| size_t bottom_index = _array->index_for(_bottom); |
| _array->set_offset_array(bottom_index, 0); |
| } |
| |
| size_t BlockOffsetArrayContigSpace::last_active_index() const { |
| size_t result = _next_offset_index - 1; |
| return result >= 0 ? result : 0; |
| } |
