--- a/src/hotspot/share/gc/parallel/cardTableExtension.cpp Mon Feb 26 09:34:20 2018 +0100
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,683 +0,0 @@
-/*
- * Copyright (c) 2001, 2018, 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/parallel/cardTableExtension.hpp"
-#include "gc/parallel/gcTaskManager.hpp"
-#include "gc/parallel/objectStartArray.inline.hpp"
-#include "gc/parallel/parallelScavengeHeap.inline.hpp"
-#include "gc/parallel/psPromotionManager.inline.hpp"
-#include "gc/parallel/psScavenge.hpp"
-#include "gc/parallel/psTasks.hpp"
-#include "gc/parallel/psYoungGen.hpp"
-#include "oops/oop.inline.hpp"
-#include "runtime/prefetch.inline.hpp"
-#include "utilities/align.hpp"
-
-// Checks an individual oop for missing precise marks. Mark
-// may be either dirty or newgen.
-class CheckForUnmarkedOops : public OopClosure {
- private:
- PSYoungGen* _young_gen;
- CardTableExtension* _card_table;
- HeapWord* _unmarked_addr;
-
- protected:
- template <class T> void do_oop_work(T* p) {
- oop obj = oopDesc::load_decode_heap_oop(p);
- if (_young_gen->is_in_reserved(obj) &&
- !_card_table->addr_is_marked_imprecise(p)) {
- // Don't overwrite the first missing card mark
- if (_unmarked_addr == NULL) {
- _unmarked_addr = (HeapWord*)p;
- }
- }
- }
-
- public:
- CheckForUnmarkedOops(PSYoungGen* young_gen, CardTableExtension* card_table) :
- _young_gen(young_gen), _card_table(card_table), _unmarked_addr(NULL) { }
-
- virtual void do_oop(oop* p) { CheckForUnmarkedOops::do_oop_work(p); }
- virtual void do_oop(narrowOop* p) { CheckForUnmarkedOops::do_oop_work(p); }
-
- bool has_unmarked_oop() {
- return _unmarked_addr != NULL;
- }
-};
-
-// Checks all objects for the existence of some type of mark,
-// precise or imprecise, dirty or newgen.
-class CheckForUnmarkedObjects : public ObjectClosure {
- private:
- PSYoungGen* _young_gen;
- CardTableExtension* _card_table;
-
- public:
- CheckForUnmarkedObjects() {
- ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
- _young_gen = heap->young_gen();
- _card_table = barrier_set_cast<CardTableExtension>(heap->barrier_set());
- // No point in asserting barrier set type here. Need to make CardTableExtension
- // a unique barrier set type.
- }
-
- // Card marks are not precise. The current system can leave us with
- // a mismatch of precise marks and beginning of object marks. This means
- // we test for missing precise marks first. If any are found, we don't
- // fail unless the object head is also unmarked.
- virtual void do_object(oop obj) {
- CheckForUnmarkedOops object_check(_young_gen, _card_table);
- obj->oop_iterate_no_header(&object_check);
- if (object_check.has_unmarked_oop()) {
- guarantee(_card_table->addr_is_marked_imprecise(obj), "Found unmarked young_gen object");
- }
- }
-};
-
-// Checks for precise marking of oops as newgen.
-class CheckForPreciseMarks : public OopClosure {
- private:
- PSYoungGen* _young_gen;
- CardTableExtension* _card_table;
-
- protected:
- template <class T> void do_oop_work(T* p) {
- oop obj = oopDesc::load_decode_heap_oop_not_null(p);
- if (_young_gen->is_in_reserved(obj)) {
- assert(_card_table->addr_is_marked_precise(p), "Found unmarked precise oop");
- _card_table->set_card_newgen(p);
- }
- }
-
- public:
- CheckForPreciseMarks( PSYoungGen* young_gen, CardTableExtension* card_table ) :
- _young_gen(young_gen), _card_table(card_table) { }
-
- virtual void do_oop(oop* p) { CheckForPreciseMarks::do_oop_work(p); }
- virtual void do_oop(narrowOop* p) { CheckForPreciseMarks::do_oop_work(p); }
-};
-
-// We get passed the space_top value to prevent us from traversing into
-// the old_gen promotion labs, which cannot be safely parsed.
-
-// Do not call this method if the space is empty.
-// It is a waste to start tasks and get here only to
-// do no work. If this method needs to be called
-// when the space is empty, fix the calculation of
-// end_card to allow sp_top == sp->bottom().
-
-void CardTableExtension::scavenge_contents_parallel(ObjectStartArray* start_array,
- MutableSpace* sp,
- HeapWord* space_top,
- PSPromotionManager* pm,
- uint stripe_number,
- uint stripe_total) {
- int ssize = 128; // Naked constant! Work unit = 64k.
- int dirty_card_count = 0;
-
- // It is a waste to get here if empty.
- assert(sp->bottom() < sp->top(), "Should not be called if empty");
- oop* sp_top = (oop*)space_top;
- jbyte* start_card = byte_for(sp->bottom());
- jbyte* end_card = byte_for(sp_top - 1) + 1;
- oop* last_scanned = NULL; // Prevent scanning objects more than once
- // The width of the stripe ssize*stripe_total must be
- // consistent with the number of stripes so that the complete slice
- // is covered.
- size_t slice_width = ssize * stripe_total;
- for (jbyte* slice = start_card; slice < end_card; slice += slice_width) {
- jbyte* worker_start_card = slice + stripe_number * ssize;
- if (worker_start_card >= end_card)
- return; // We're done.
-
- jbyte* worker_end_card = worker_start_card + ssize;
- if (worker_end_card > end_card)
- worker_end_card = end_card;
-
- // We do not want to scan objects more than once. In order to accomplish
- // this, we assert that any object with an object head inside our 'slice'
- // belongs to us. We may need to extend the range of scanned cards if the
- // last object continues into the next 'slice'.
- //
- // Note! ending cards are exclusive!
- HeapWord* slice_start = addr_for(worker_start_card);
- HeapWord* slice_end = MIN2((HeapWord*) sp_top, addr_for(worker_end_card));
-
-#ifdef ASSERT
- if (GCWorkerDelayMillis > 0) {
- // Delay 1 worker so that it proceeds after all the work
- // has been completed.
- if (stripe_number < 2) {
- os::sleep(Thread::current(), GCWorkerDelayMillis, false);
- }
- }
-#endif
-
- // If there are not objects starting within the chunk, skip it.
- if (!start_array->object_starts_in_range(slice_start, slice_end)) {
- continue;
- }
- // Update our beginning addr
- HeapWord* first_object = start_array->object_start(slice_start);
- debug_only(oop* first_object_within_slice = (oop*) first_object;)
- if (first_object < slice_start) {
- last_scanned = (oop*)(first_object + oop(first_object)->size());
- debug_only(first_object_within_slice = last_scanned;)
- worker_start_card = byte_for(last_scanned);
- }
-
- // Update the ending addr
- if (slice_end < (HeapWord*)sp_top) {
- // The subtraction is important! An object may start precisely at slice_end.
- HeapWord* last_object = start_array->object_start(slice_end - 1);
- slice_end = last_object + oop(last_object)->size();
- // worker_end_card is exclusive, so bump it one past the end of last_object's
- // covered span.
- worker_end_card = byte_for(slice_end) + 1;
-
- if (worker_end_card > end_card)
- worker_end_card = end_card;
- }
-
- assert(slice_end <= (HeapWord*)sp_top, "Last object in slice crosses space boundary");
- assert(is_valid_card_address(worker_start_card), "Invalid worker start card");
- assert(is_valid_card_address(worker_end_card), "Invalid worker end card");
- // Note that worker_start_card >= worker_end_card is legal, and happens when
- // an object spans an entire slice.
- assert(worker_start_card <= end_card, "worker start card beyond end card");
- assert(worker_end_card <= end_card, "worker end card beyond end card");
-
- jbyte* current_card = worker_start_card;
- while (current_card < worker_end_card) {
- // Find an unclean card.
- while (current_card < worker_end_card && card_is_clean(*current_card)) {
- current_card++;
- }
- jbyte* first_unclean_card = current_card;
-
- // Find the end of a run of contiguous unclean cards
- while (current_card < worker_end_card && !card_is_clean(*current_card)) {
- while (current_card < worker_end_card && !card_is_clean(*current_card)) {
- current_card++;
- }
-
- if (current_card < worker_end_card) {
- // Some objects may be large enough to span several cards. If such
- // an object has more than one dirty card, separated by a clean card,
- // we will attempt to scan it twice. The test against "last_scanned"
- // prevents the redundant object scan, but it does not prevent newly
- // marked cards from being cleaned.
- HeapWord* last_object_in_dirty_region = start_array->object_start(addr_for(current_card)-1);
- size_t size_of_last_object = oop(last_object_in_dirty_region)->size();
- HeapWord* end_of_last_object = last_object_in_dirty_region + size_of_last_object;
- jbyte* ending_card_of_last_object = byte_for(end_of_last_object);
- assert(ending_card_of_last_object <= worker_end_card, "ending_card_of_last_object is greater than worker_end_card");
- if (ending_card_of_last_object > current_card) {
- // This means the object spans the next complete card.
- // We need to bump the current_card to ending_card_of_last_object
- current_card = ending_card_of_last_object;
- }
- }
- }
- jbyte* following_clean_card = current_card;
-
- if (first_unclean_card < worker_end_card) {
- oop* p = (oop*) start_array->object_start(addr_for(first_unclean_card));
- assert((HeapWord*)p <= addr_for(first_unclean_card), "checking");
- // "p" should always be >= "last_scanned" because newly GC dirtied
- // cards are no longer scanned again (see comment at end
- // of loop on the increment of "current_card"). Test that
- // hypothesis before removing this code.
- // If this code is removed, deal with the first time through
- // the loop when the last_scanned is the object starting in
- // the previous slice.
- assert((p >= last_scanned) ||
- (last_scanned == first_object_within_slice),
- "Should no longer be possible");
- if (p < last_scanned) {
- // Avoid scanning more than once; this can happen because
- // newgen cards set by GC may a different set than the
- // originally dirty set
- p = last_scanned;
- }
- oop* to = (oop*)addr_for(following_clean_card);
-
- // Test slice_end first!
- if ((HeapWord*)to > slice_end) {
- to = (oop*)slice_end;
- } else if (to > sp_top) {
- to = sp_top;
- }
-
- // we know which cards to scan, now clear them
- if (first_unclean_card <= worker_start_card+1)
- first_unclean_card = worker_start_card+1;
- if (following_clean_card >= worker_end_card-1)
- following_clean_card = worker_end_card-1;
-
- while (first_unclean_card < following_clean_card) {
- *first_unclean_card++ = clean_card;
- }
-
- const int interval = PrefetchScanIntervalInBytes;
- // scan all objects in the range
- if (interval != 0) {
- while (p < to) {
- Prefetch::write(p, interval);
- oop m = oop(p);
- assert(oopDesc::is_oop_or_null(m), "Expected an oop or NULL for header field at " PTR_FORMAT, p2i(m));
- pm->push_contents(m);
- p += m->size();
- }
- pm->drain_stacks_cond_depth();
- } else {
- while (p < to) {
- oop m = oop(p);
- assert(oopDesc::is_oop_or_null(m), "Expected an oop or NULL for header field at " PTR_FORMAT, p2i(m));
- pm->push_contents(m);
- p += m->size();
- }
- pm->drain_stacks_cond_depth();
- }
- last_scanned = p;
- }
- // "current_card" is still the "following_clean_card" or
- // the current_card is >= the worker_end_card so the
- // loop will not execute again.
- assert((current_card == following_clean_card) ||
- (current_card >= worker_end_card),
- "current_card should only be incremented if it still equals "
- "following_clean_card");
- // Increment current_card so that it is not processed again.
- // It may now be dirty because a old-to-young pointer was
- // found on it an updated. If it is now dirty, it cannot be
- // be safely cleaned in the next iteration.
- current_card++;
- }
- }
-}
-
-// This should be called before a scavenge.
-void CardTableExtension::verify_all_young_refs_imprecise() {
- CheckForUnmarkedObjects check;
-
- ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
- PSOldGen* old_gen = heap->old_gen();
-
- old_gen->object_iterate(&check);
-}
-
-// This should be called immediately after a scavenge, before mutators resume.
-void CardTableExtension::verify_all_young_refs_precise() {
- ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
- PSOldGen* old_gen = heap->old_gen();
-
- CheckForPreciseMarks check(
- heap->young_gen(),
- barrier_set_cast<CardTableExtension>(heap->barrier_set()));
-
- old_gen->oop_iterate_no_header(&check);
-
- verify_all_young_refs_precise_helper(old_gen->object_space()->used_region());
-}
-
-void CardTableExtension::verify_all_young_refs_precise_helper(MemRegion mr) {
- CardTableExtension* card_table =
- barrier_set_cast<CardTableExtension>(ParallelScavengeHeap::heap()->barrier_set());
-
- jbyte* bot = card_table->byte_for(mr.start());
- jbyte* top = card_table->byte_for(mr.end());
- while(bot <= top) {
- assert(*bot == clean_card || *bot == verify_card, "Found unwanted or unknown card mark");
- if (*bot == verify_card)
- *bot = youngergen_card;
- bot++;
- }
-}
-
-bool CardTableExtension::addr_is_marked_imprecise(void *addr) {
- jbyte* p = byte_for(addr);
- jbyte val = *p;
-
- if (card_is_dirty(val))
- return true;
-
- if (card_is_newgen(val))
- return true;
-
- if (card_is_clean(val))
- return false;
-
- assert(false, "Found unhandled card mark type");
-
- return false;
-}
-
-// Also includes verify_card
-bool CardTableExtension::addr_is_marked_precise(void *addr) {
- jbyte* p = byte_for(addr);
- jbyte val = *p;
-
- if (card_is_newgen(val))
- return true;
-
- if (card_is_verify(val))
- return true;
-
- if (card_is_clean(val))
- return false;
-
- if (card_is_dirty(val))
- return false;
-
- assert(false, "Found unhandled card mark type");
-
- return false;
-}
-
-// Assumes that only the base or the end changes. This allows indentification
-// of the region that is being resized. The
-// CardTableModRefBS::resize_covered_region() is used for the normal case
-// where the covered regions are growing or shrinking at the high end.
-// The method resize_covered_region_by_end() is analogous to
-// CardTableModRefBS::resize_covered_region() but
-// for regions that grow or shrink at the low end.
-void CardTableExtension::resize_covered_region(MemRegion new_region) {
-
- for (int i = 0; i < _cur_covered_regions; i++) {
- if (_covered[i].start() == new_region.start()) {
- // Found a covered region with the same start as the
- // new region. The region is growing or shrinking
- // from the start of the region.
- resize_covered_region_by_start(new_region);
- return;
- }
- if (_covered[i].start() > new_region.start()) {
- break;
- }
- }
-
- int changed_region = -1;
- for (int j = 0; j < _cur_covered_regions; j++) {
- if (_covered[j].end() == new_region.end()) {
- changed_region = j;
- // This is a case where the covered region is growing or shrinking
- // at the start of the region.
- assert(changed_region != -1, "Don't expect to add a covered region");
- assert(_covered[changed_region].byte_size() != new_region.byte_size(),
- "The sizes should be different here");
- resize_covered_region_by_end(changed_region, new_region);
- return;
- }
- }
- // This should only be a new covered region (where no existing
- // covered region matches at the start or the end).
- assert(_cur_covered_regions < _max_covered_regions,
- "An existing region should have been found");
- resize_covered_region_by_start(new_region);
-}
-
-void CardTableExtension::resize_covered_region_by_start(MemRegion new_region) {
- CardTableModRefBS::resize_covered_region(new_region);
- debug_only(verify_guard();)
-}
-
-void CardTableExtension::resize_covered_region_by_end(int changed_region,
- MemRegion new_region) {
- assert(SafepointSynchronize::is_at_safepoint(),
- "Only expect an expansion at the low end at a GC");
- debug_only(verify_guard();)
-#ifdef ASSERT
- for (int k = 0; k < _cur_covered_regions; k++) {
- if (_covered[k].end() == new_region.end()) {
- assert(changed_region == k, "Changed region is incorrect");
- break;
- }
- }
-#endif
-
- // Commit new or uncommit old pages, if necessary.
- if (resize_commit_uncommit(changed_region, new_region)) {
- // Set the new start of the committed region
- resize_update_committed_table(changed_region, new_region);
- }
-
- // Update card table entries
- resize_update_card_table_entries(changed_region, new_region);
-
- // Update the covered region
- resize_update_covered_table(changed_region, new_region);
-
- int ind = changed_region;
- log_trace(gc, barrier)("CardTableModRefBS::resize_covered_region: ");
- log_trace(gc, barrier)(" _covered[%d].start(): " INTPTR_FORMAT " _covered[%d].last(): " INTPTR_FORMAT,
- ind, p2i(_covered[ind].start()), ind, p2i(_covered[ind].last()));
- log_trace(gc, barrier)(" _committed[%d].start(): " INTPTR_FORMAT " _committed[%d].last(): " INTPTR_FORMAT,
- ind, p2i(_committed[ind].start()), ind, p2i(_committed[ind].last()));
- log_trace(gc, barrier)(" byte_for(start): " INTPTR_FORMAT " byte_for(last): " INTPTR_FORMAT,
- p2i(byte_for(_covered[ind].start())), p2i(byte_for(_covered[ind].last())));
- log_trace(gc, barrier)(" addr_for(start): " INTPTR_FORMAT " addr_for(last): " INTPTR_FORMAT,
- p2i(addr_for((jbyte*) _committed[ind].start())), p2i(addr_for((jbyte*) _committed[ind].last())));
-
- debug_only(verify_guard();)
-}
-
-bool CardTableExtension::resize_commit_uncommit(int changed_region,
- MemRegion new_region) {
- bool result = false;
- // Commit new or uncommit old pages, if necessary.
- MemRegion cur_committed = _committed[changed_region];
- assert(_covered[changed_region].end() == new_region.end(),
- "The ends of the regions are expected to match");
- // Extend the start of this _committed region to
- // to cover the start of any previous _committed region.
- // This forms overlapping regions, but never interior regions.
- HeapWord* min_prev_start = lowest_prev_committed_start(changed_region);
- if (min_prev_start < cur_committed.start()) {
- // Only really need to set start of "cur_committed" to
- // the new start (min_prev_start) but assertion checking code
- // below use cur_committed.end() so make it correct.
- MemRegion new_committed =
- MemRegion(min_prev_start, cur_committed.end());
- cur_committed = new_committed;
- }
-#ifdef ASSERT
- ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
- assert(cur_committed.start() == align_up(cur_committed.start(), os::vm_page_size()),
- "Starts should have proper alignment");
-#endif
-
- jbyte* new_start = byte_for(new_region.start());
- // Round down because this is for the start address
- HeapWord* new_start_aligned =
- (HeapWord*)align_down((uintptr_t)new_start, os::vm_page_size());
- // The guard page is always committed and should not be committed over.
- // This method is used in cases where the generation is growing toward
- // lower addresses but the guard region is still at the end of the
- // card table. That still makes sense when looking for writes
- // off the end of the card table.
- if (new_start_aligned < cur_committed.start()) {
- // Expand the committed region
- //
- // Case A
- // |+ guard +|
- // |+ cur committed +++++++++|
- // |+ new committed +++++++++++++++++|
- //
- // Case B
- // |+ guard +|
- // |+ cur committed +|
- // |+ new committed +++++++|
- //
- // These are not expected because the calculation of the
- // cur committed region and the new committed region
- // share the same end for the covered region.
- // Case C
- // |+ guard +|
- // |+ cur committed +|
- // |+ new committed +++++++++++++++++|
- // Case D
- // |+ guard +|
- // |+ cur committed +++++++++++|
- // |+ new committed +++++++|
-
- HeapWord* new_end_for_commit =
- MIN2(cur_committed.end(), _guard_region.start());
- if(new_start_aligned < new_end_for_commit) {
- MemRegion new_committed =
- MemRegion(new_start_aligned, new_end_for_commit);
- os::commit_memory_or_exit((char*)new_committed.start(),
- new_committed.byte_size(), !ExecMem,
- "card table expansion");
- }
- result = true;
- } else if (new_start_aligned > cur_committed.start()) {
- // Shrink the committed region
-#if 0 // uncommitting space is currently unsafe because of the interactions
- // of growing and shrinking regions. One region A can uncommit space
- // that it owns but which is being used by another region B (maybe).
- // Region B has not committed the space because it was already
- // committed by region A.
- MemRegion uncommit_region = committed_unique_to_self(changed_region,
- MemRegion(cur_committed.start(), new_start_aligned));
- if (!uncommit_region.is_empty()) {
- if (!os::uncommit_memory((char*)uncommit_region.start(),
- uncommit_region.byte_size())) {
- // If the uncommit fails, ignore it. Let the
- // committed table resizing go even though the committed
- // table will over state the committed space.
- }
- }
-#else
- assert(!result, "Should be false with current workaround");
-#endif
- }
- assert(_committed[changed_region].end() == cur_committed.end(),
- "end should not change");
- return result;
-}
-
-void CardTableExtension::resize_update_committed_table(int changed_region,
- MemRegion new_region) {
-
- jbyte* new_start = byte_for(new_region.start());
- // Set the new start of the committed region
- HeapWord* new_start_aligned =
- (HeapWord*)align_down(new_start, os::vm_page_size());
- MemRegion new_committed = MemRegion(new_start_aligned,
- _committed[changed_region].end());
- _committed[changed_region] = new_committed;
- _committed[changed_region].set_start(new_start_aligned);
-}
-
-void CardTableExtension::resize_update_card_table_entries(int changed_region,
- MemRegion new_region) {
- debug_only(verify_guard();)
- MemRegion original_covered = _covered[changed_region];
- // Initialize the card entries. Only consider the
- // region covered by the card table (_whole_heap)
- jbyte* entry;
- if (new_region.start() < _whole_heap.start()) {
- entry = byte_for(_whole_heap.start());
- } else {
- entry = byte_for(new_region.start());
- }
- jbyte* end = byte_for(original_covered.start());
- // If _whole_heap starts at the original covered regions start,
- // this loop will not execute.
- while (entry < end) { *entry++ = clean_card; }
-}
-
-void CardTableExtension::resize_update_covered_table(int changed_region,
- MemRegion new_region) {
- // Update the covered region
- _covered[changed_region].set_start(new_region.start());
- _covered[changed_region].set_word_size(new_region.word_size());
-
- // reorder regions. There should only be at most 1 out
- // of order.
- for (int i = _cur_covered_regions-1 ; i > 0; i--) {
- if (_covered[i].start() < _covered[i-1].start()) {
- MemRegion covered_mr = _covered[i-1];
- _covered[i-1] = _covered[i];
- _covered[i] = covered_mr;
- MemRegion committed_mr = _committed[i-1];
- _committed[i-1] = _committed[i];
- _committed[i] = committed_mr;
- break;
- }
- }
-#ifdef ASSERT
- for (int m = 0; m < _cur_covered_regions-1; m++) {
- assert(_covered[m].start() <= _covered[m+1].start(),
- "Covered regions out of order");
- assert(_committed[m].start() <= _committed[m+1].start(),
- "Committed regions out of order");
- }
-#endif
-}
-
-// Returns the start of any committed region that is lower than
-// the target committed region (index ind) and that intersects the
-// target region. If none, return start of target region.
-//
-// -------------
-// | |
-// -------------
-// ------------
-// | target |
-// ------------
-// -------------
-// | |
-// -------------
-// ^ returns this
-//
-// -------------
-// | |
-// -------------
-// ------------
-// | target |
-// ------------
-// -------------
-// | |
-// -------------
-// ^ returns this
-
-HeapWord* CardTableExtension::lowest_prev_committed_start(int ind) const {
- assert(_cur_covered_regions >= 0, "Expecting at least on region");
- HeapWord* min_start = _committed[ind].start();
- for (int j = 0; j < ind; j++) {
- HeapWord* this_start = _committed[j].start();
- if ((this_start < min_start) &&
- !(_committed[j].intersection(_committed[ind])).is_empty()) {
- min_start = this_start;
- }
- }
- return min_start;
-}
-
-bool CardTableExtension::is_in_young(oop obj) const {
- return ParallelScavengeHeap::heap()->is_in_young(obj);
-}