Mercurial > hg > graal-jvmci-8
diff src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp @ 342:37f87013dfd8
6711316: Open source the Garbage-First garbage collector
Summary: First mercurial integration of the code for the Garbage-First garbage collector.
Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr
author | ysr |
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date | Thu, 05 Jun 2008 15:57:56 -0700 |
parents | |
children | e0c09f7ec5c4 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/gc_implementation/g1/g1BlockOffsetTable.cpp Thu Jun 05 15:57:56 2008 -0700 @@ -0,0 +1,624 @@ +/* + * Copyright 2001-2007 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/_g1BlockOffsetTable.cpp.incl" + +////////////////////////////////////////////////////////////////////// +// G1BlockOffsetSharedArray +////////////////////////////////////////////////////////////////////// + +G1BlockOffsetSharedArray::G1BlockOffsetSharedArray(MemRegion reserved, + size_t init_word_size) : + _reserved(reserved), _end(NULL) +{ + size_t size = compute_size(reserved.word_size()); + ReservedSpace rs(ReservedSpace::allocation_align_size_up(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("G1BlockOffsetSharedArray::G1BlockOffsetSharedArray: "); + 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 G1BlockOffsetSharedArray::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"); + // Initialization of the contents is left to the + // G1BlockOffsetArray that uses it. + } 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 G1BlockOffsetSharedArray::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; +} + + +////////////////////////////////////////////////////////////////////// +// G1BlockOffsetArray +////////////////////////////////////////////////////////////////////// + +G1BlockOffsetArray::G1BlockOffsetArray(G1BlockOffsetSharedArray* array, + MemRegion mr, bool init_to_zero) : + G1BlockOffsetTable(mr.start(), mr.end()), + _unallocated_block(_bottom), + _array(array), _csp(NULL), + _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 + } +} + +void G1BlockOffsetArray::set_space(Space* sp) { + _sp = sp; + _csp = sp->toContiguousSpace(); +} + +// The arguments follow the normal convention of denoting +// a right-open interval: [start, end) +void +G1BlockOffsetArray:: 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 +G1BlockOffsetArray::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 < BlockOffsetArray::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 + (BlockOffsetArray::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 block [blk_start, blk_end) has been allocated; +// adjust the block offset table to represent this information; +// right-open interval: [blk_start, blk_end) +void +G1BlockOffsetArray::alloc_block(HeapWord* blk_start, HeapWord* blk_end) { + mark_block(blk_start, blk_end); + allocated(blk_start, blk_end); +} + +// Adjust BOT to show that a previously whole block has been split +// into two. +void G1BlockOffsetArray::split_block(HeapWord* blk, size_t blk_size, + size_t left_blk_size) { + // Verify that the BOT shows [blk, blk + blk_size) to be one block. + verify_single_block(blk, blk_size); + // Update the BOT to indicate that [blk + left_blk_size, blk + blk_size) + // is one single block. + mark_block(blk + left_blk_size, blk + blk_size); +} + + +// 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 G1BlockOffsetArray::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 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 G1BlockOffsetArray::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 > BlockOffsetArray::power_to_cards_back(1)) { + guarantee(entry > N_words, "Should be in logarithmic region"); + } + size_t backskip = BlockOffsetArray::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"); + } + } +} + +// 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 +G1BlockOffsetArray::single_block(HeapWord* blk_start, HeapWord* blk_end) { + do_block_internal(blk_start, blk_end, Action_single); +} + +// 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 +G1BlockOffsetArray::mark_block(HeapWord* blk_start, HeapWord* blk_end) { + do_block_internal(blk_start, blk_end, Action_mark); +} + +void G1BlockOffsetArray::join_blocks(HeapWord* blk1, HeapWord* blk2) { + HeapWord* blk1_start = Universe::heap()->block_start(blk1); + HeapWord* blk2_start = Universe::heap()->block_start(blk2); + assert(blk1 == blk1_start && blk2 == blk2_start, + "Must be block starts."); + assert(blk1 + _sp->block_size(blk1) == blk2, "Must be contiguous."); + size_t blk1_start_index = _array->index_for(blk1); + size_t blk2_start_index = _array->index_for(blk2); + assert(blk1_start_index <= blk2_start_index, "sanity"); + HeapWord* blk2_card_start = _array->address_for_index(blk2_start_index); + if (blk2 == blk2_card_start) { + // blk2 starts a card. Does blk1 start on the prevous card, or futher + // back? + assert(blk1_start_index < blk2_start_index, "must be lower card."); + if (blk1_start_index + 1 == blk2_start_index) { + // previous card; new value for blk2 card is size of blk1. + _array->set_offset_array(blk2_start_index, (u_char) _sp->block_size(blk1)); + } else { + // Earlier card; go back a card. + _array->set_offset_array(blk2_start_index, N_words); + } + } else { + // blk2 does not start a card. Does it cross a card? If not, nothing + // to do. + size_t blk2_end_index = + _array->index_for(blk2 + _sp->block_size(blk2) - 1); + assert(blk2_end_index >= blk2_start_index, "sanity"); + if (blk2_end_index > blk2_start_index) { + // Yes, it crosses a card. The value for the next card must change. + if (blk1_start_index + 1 == blk2_start_index) { + // previous card; new value for second blk2 card is size of blk1. + _array->set_offset_array(blk2_start_index + 1, + (u_char) _sp->block_size(blk1)); + } else { + // Earlier card; go back a card. + _array->set_offset_array(blk2_start_index + 1, N_words); + } + } + } +} + +HeapWord* G1BlockOffsetArray::block_start_unsafe(const void* addr) { + 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. + HeapWord* q = block_at_or_preceding(addr, false, 0); + return forward_to_block_containing_addr(q, addr); +} + +// This duplicates a little code from the above: unavoidable. +HeapWord* +G1BlockOffsetArray::block_start_unsafe_const(const void* addr) const { + 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. + HeapWord* q = block_at_or_preceding(addr, false, 0); + HeapWord* n = q + _sp->block_size(q); + return forward_to_block_containing_addr_const(q, n, addr); +} + + +HeapWord* +G1BlockOffsetArray::forward_to_block_containing_addr_slow(HeapWord* q, + HeapWord* n, + const void* addr) { + // We're not in the normal case. We need to handle an important subcase + // here: LAB allocation. An allocation previously recorded in the + // offset table was actually a lab allocation, and was divided into + // several objects subsequently. Fix this situation as we answer the + // query, by updating entries as we cross them. + size_t next_index = _array->index_for(n) + 1; + HeapWord* next_boundary = _array->address_for_index(next_index); + if (csp() != NULL) { + if (addr >= csp()->top()) return csp()->top(); + while (next_boundary < addr) { + while (n <= next_boundary) { + q = n; + oop obj = oop(q); + if (obj->klass() == NULL) return q; + n += obj->size(); + } + assert(q <= next_boundary && n > next_boundary, "Consequence of loop"); + // [q, n) is the block that crosses the boundary. + alloc_block_work2(&next_boundary, &next_index, q, n); + } + } else { + while (next_boundary < addr) { + while (n <= next_boundary) { + q = n; + oop obj = oop(q); + if (obj->klass() == NULL) return q; + n += _sp->block_size(q); + } + assert(q <= next_boundary && n > next_boundary, "Consequence of loop"); + // [q, n) is the block that crosses the boundary. + alloc_block_work2(&next_boundary, &next_index, q, n); + } + } + return forward_to_block_containing_addr_const(q, n, addr); +} + +HeapWord* G1BlockOffsetArray::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--); + q -= offset; + } while (offset == N_words); + assert(q <= addr, "block start should be to left of arg"); + return q; +} + +// Note that the committed size of the covered space may have changed, +// so the table size might also wish to change. +void G1BlockOffsetArray::resize(size_t new_word_size) { + HeapWord* new_end = _bottom + new_word_size; + if (_end < new_end && !init_to_zero()) { + // verify that the old and new boundaries are also card boundaries + assert(_array->is_card_boundary(_end), + "_end not a card boundary"); + assert(_array->is_card_boundary(new_end), + "new _end would not be a card boundary"); + // set all the newly added cards + _array->set_offset_array(_end, new_end, N_words); + } + _end = new_end; // update _end +} + +void G1BlockOffsetArray::set_region(MemRegion mr) { + _bottom = mr.start(); + _end = mr.end(); +} + +// +// threshold_ +// | _index_ +// v v +// +-------+-------+-------+-------+-------+ +// | i-1 | i | i+1 | i+2 | i+3 | +// +-------+-------+-------+-------+-------+ +// ( ^ ] +// block-start +// +void G1BlockOffsetArray::alloc_block_work2(HeapWord** threshold_, size_t* index_, + HeapWord* blk_start, HeapWord* blk_end) { + // For efficiency, do copy-in/copy-out. + HeapWord* threshold = *threshold_; + size_t index = *index_; + + assert(blk_start != NULL && blk_end > blk_start, + "phantom block"); + assert(blk_end > threshold, "should be past threshold"); + assert(blk_start <= threshold, "blk_start should be at or before threshold") + assert(pointer_delta(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(threshold == _array->_reserved.start() + index*N_words, + "index must agree with threshold"); + + DEBUG_ONLY(size_t orig_index = 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(index, 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 (index + 1 <= end_index) { + HeapWord* rem_st = _array->address_for_index(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); + } + + index = end_index + 1; + // Calculate threshold_ this way because end_index + // may be the last valid index in the covered region. + threshold = _array->address_for_index(end_index) + N_words; + assert(threshold >= blk_end, "Incorrect offset threshold"); + + // index_ and threshold_ updated here. + *threshold_ = threshold; + *index_ = index; + +#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_index) == 0 && + blk_start == boundary) || + (_array->offset_array(orig_index) > 0 && + _array->offset_array(orig_index) <= N_words), + "offset array should have been set"); + for (size_t j = orig_index + 1; j <= end_index; j++) { + assert(_array->offset_array(j) > 0 && + _array->offset_array(j) <= + (u_char) (N_words+BlockOffsetArray::N_powers-1), + "offset array should have been set"); + } +#endif +} + +////////////////////////////////////////////////////////////////////// +// G1BlockOffsetArrayContigSpace +////////////////////////////////////////////////////////////////////// + +HeapWord* +G1BlockOffsetArrayContigSpace::block_start_unsafe(const void* addr) { + assert(_bottom <= addr && addr < _end, + "addr must be covered by this Array"); + HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1); + return forward_to_block_containing_addr(q, addr); +} + +HeapWord* +G1BlockOffsetArrayContigSpace:: +block_start_unsafe_const(const void* addr) const { + assert(_bottom <= addr && addr < _end, + "addr must be covered by this Array"); + HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1); + HeapWord* n = q + _sp->block_size(q); + return forward_to_block_containing_addr_const(q, n, addr); +} + +G1BlockOffsetArrayContigSpace:: +G1BlockOffsetArrayContigSpace(G1BlockOffsetSharedArray* array, + MemRegion mr) : + G1BlockOffsetArray(array, mr, true) +{ + _next_offset_threshold = NULL; + _next_offset_index = 0; +} + +HeapWord* G1BlockOffsetArrayContigSpace::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 G1BlockOffsetArrayContigSpace::zero_bottom_entry() { + assert(!Universe::heap()->is_in_reserved(_array->_offset_array), + "just checking"); + size_t bottom_index = _array->index_for(_bottom); + assert(_array->address_for_index(bottom_index) == _bottom, + "Precondition of call"); + _array->set_offset_array(bottom_index, 0); +}