| /* |
| * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "gc_implementation/parallelScavenge/cardTableExtension.hpp" |
| #include "gc_implementation/parallelScavenge/gcTaskManager.hpp" |
| #include "gc_implementation/parallelScavenge/parallelScavengeHeap.hpp" |
| #include "gc_implementation/parallelScavenge/psTasks.hpp" |
| #include "gc_implementation/parallelScavenge/psYoungGen.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "oops/oop.psgc.inline.hpp" |
| #include "runtime/prefetch.inline.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; |
| jbyte* _unmarked_card; |
| |
| 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; |
| _unmarked_card = _card_table->byte_for(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 existance 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*)Universe::heap(); |
| assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); |
| |
| _young_gen = heap->young_gen(); |
| _card_table = (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 mismash 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()) { |
| assert(_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(m->is_oop_or_null(), "check for header"); |
| m->push_contents(pm); |
| p += m->size(); |
| } |
| pm->drain_stacks_cond_depth(); |
| } else { |
| while (p < to) { |
| oop m = oop(p); |
| assert(m->is_oop_or_null(), "check for header"); |
| m->push_contents(pm); |
| 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*)Universe::heap(); |
| assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); |
| |
| 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*)Universe::heap(); |
| assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity"); |
| |
| PSOldGen* old_gen = heap->old_gen(); |
| |
| CheckForPreciseMarks check(heap->young_gen(), (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 = (CardTableExtension*)Universe::heap()->barrier_set(); |
| // FIX ME ASSERT HERE |
| |
| 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); |
| |
| if (TraceCardTableModRefBS) { |
| int ind = changed_region; |
| gclog_or_tty->print_cr("CardTableModRefBS::resize_covered_region: "); |
| gclog_or_tty->print_cr(" " |
| " _covered[%d].start(): " INTPTR_FORMAT |
| " _covered[%d].last(): " INTPTR_FORMAT, |
| ind, p2i(_covered[ind].start()), |
| ind, p2i(_covered[ind].last())); |
| gclog_or_tty->print_cr(" " |
| " _committed[%d].start(): " INTPTR_FORMAT |
| " _committed[%d].last(): " INTPTR_FORMAT, |
| ind, p2i(_committed[ind].start()), |
| ind, p2i(_committed[ind].last())); |
| gclog_or_tty->print_cr(" " |
| " byte_for(start): " INTPTR_FORMAT |
| " byte_for(last): " INTPTR_FORMAT, |
| p2i(byte_for(_covered[ind].start())), |
| p2i(byte_for(_covered[ind].last()))); |
| gclog_or_tty->print_cr(" " |
| " 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*)Universe::heap(); |
| assert(cur_committed.start() == |
| (HeapWord*) align_size_up((uintptr_t) 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_size_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_size_down((uintptr_t)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; |
| } |
