--- old/src/share/vm/memory/blockOffsetTable.cpp 2015-05-12 11:41:19.295877597 +0200 +++ /dev/null 2015-03-18 17:10:38.111854831 +0100 @@ -1,796 +0,0 @@ -/* - * Copyright (c) 2000, 2015, 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 themselves. - 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 { - return _next_offset_index == 0 ? 0 : _next_offset_index - 1; -} --- /dev/null 2015-03-18 17:10:38.111854831 +0100 +++ new/src/share/vm/gc/shared/blockOffsetTable.cpp 2015-05-12 11:41:19.013865851 +0200 @@ -0,0 +1,796 @@ +/* + * Copyright (c) 2000, 2015, 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/shared/blockOffsetTable.inline.hpp" +#include "gc/shared/collectedHeap.inline.hpp" +#include "gc/shared/space.inline.hpp" +#include "memory/iterator.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 themselves. + 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 { + return _next_offset_index == 0 ? 0 : _next_offset_index - 1; +}