graal-compiler: src/share/vm/memory/blockOffsetTable.cpp comparison

comparison src/share/vm/memory/blockOffsetTable.cpp @ 0:a61af66fc99e jdk7-b24

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author	duke
date	Sat, 01 Dec 2007 00:00:00 +0000
parents
children	37f87013dfd8

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--1:000000000000
+:a61af66fc99e
+/*
+* Copyright 2000-2006 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+* CA 95054 USA or visit www.sun.com if you need additional information or
+* have any questions.
+*
+*/
+# include "incls/_precompiled.incl"
+# include "incls/_blockOffsetTable.cpp.incl"
+//////////////////////////////////////////////////////////////////////
+// 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");
+}
+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,
+rs.base(), rs.size(), rs.base() + rs.size());
+gclog_or_tty->print_cr("  "
+"  _vs.low_boundary(): " INTPTR_FORMAT
+"  _vs.high_boundary(): " INTPTR_FORMAT,
+_vs.low_boundary(),
+_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, "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;
+}
+void BlockOffsetSharedArray::serialize(SerializeOopClosure* soc,
+HeapWord* start, HeapWord* end) {
+assert(_offset_array[0] == 0, "objects can't cross covered areas");
+assert(start <= end, "bad address range");
+size_t start_index = index_for(start);
+size_t end_index = index_for(end-1)+1;
+soc->do_region(&_offset_array[start_index],
+(end_index - start_index) * sizeof(_offset_array[0]));
+}
+//////////////////////////////////////////////////////////////////////
+// BlockOffsetArray
+//////////////////////////////////////////////////////////////////////
+BlockOffsetArray::BlockOffsetArray(BlockOffsetSharedArray* array,
+MemRegion mr, bool init_to_zero) :
+BlockOffsetTable(mr.start(), mr.end()),
+_array(array),
+_init_to_zero(init_to_zero)
+{
+assert(_bottom <= _end, "arguments out of order");
+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) {
+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); // 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) {
+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-1; 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);
+start_card_for_region = reach + 1;
+break;
+}
+_array->set_offset_array(start_card_for_region, reach, offset);
+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");
+for (size_t c = start_card + 1; c <= end_card; c++ /* yeah! */) {
+u_char entry = _array->offset_array(c);
+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");
+guarantee(_array->offset_array(landing_card) <= N_words, "Offset value");
+}
+}
+}
+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) {
+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);
+break;
+} // Else fall through to the next case
+}
+case Action_single: {
+_array->set_offset_array(start_index, boundary, blk_start);
+// 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);
+}
+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 deos 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);
+// 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);
+} 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);
+// 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);
+} 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);
+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) {
+do_block_internal(blk_start, blk_end, Action_mark);
+}
+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(), "Went below bottom!");
+index -= n_cards_back;
+offset = _array->offset_array(index);
+}
+assert(offset < N_words, "offset too large");
+index--;
+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;
+}
+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, "Incorrent 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);
+}
+void BlockOffsetArrayContigSpace::serialize(SerializeOopClosure* soc) {
+if (soc->reading()) {
+// Null these values so that the serializer won't object to updating them.
+_next_offset_threshold = NULL;
+_next_offset_index = 0;
+}
+soc->do_ptr(&_next_offset_threshold);
+soc->do_size_t(&_next_offset_index);
+}
+size_t BlockOffsetArrayContigSpace::last_active_index() const {
+size_t result = _next_offset_index - 1;
+return result >= 0 ? result : 0;
+}

Mercurial > hg > graal-compiler

comparison src/share/vm/memory/blockOffsetTable.cpp @ 0:a61af66fc99e jdk7-b24