1 /*
  2  * Copyright (c) 2018, 2021, Red Hat, Inc. All rights reserved.
  3  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  5  *
  6  * This code is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 only, as
  8  * published by the Free Software Foundation.
  9  *
 10  * This code is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 13  * version 2 for more details (a copy is included in the LICENSE file that
 14  * accompanied this code).
 15  *
 16  * You should have received a copy of the GNU General Public License version
 17  * 2 along with this work; if not, write to the Free Software Foundation,
 18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 19  *
 20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 21  * or visit www.oracle.com if you need additional information or have any
 22  * questions.
 23  *
 24  */
 25 
 26 #include "precompiled.hpp"
 27 #include "gc/shared/markBitMap.inline.hpp"
 28 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
 29 #include "gc/shenandoah/shenandoahMarkingContext.hpp"
 30 
 31 ShenandoahMarkingContext::ShenandoahMarkingContext(MemRegion heap_region, MemRegion bitmap_region, size_t num_regions) :
 32   _mark_bit_map(heap_region, bitmap_region),
 33   _top_bitmaps(NEW_C_HEAP_ARRAY(HeapWord*, num_regions, mtGC)),
 34   _top_at_mark_starts_base(NEW_C_HEAP_ARRAY(HeapWord*, num_regions, mtGC)),
 35   _top_at_mark_starts(_top_at_mark_starts_base -
 36                       ((uintx) heap_region.start() >> ShenandoahHeapRegion::region_size_bytes_shift())) {
 37 }
 38 
 39 bool ShenandoahMarkingContext::is_bitmap_clear() const {
 40   ShenandoahHeap* heap = ShenandoahHeap::heap();
 41   size_t num_regions = heap->num_regions();
 42   for (size_t idx = 0; idx < num_regions; idx++) {
 43     ShenandoahHeapRegion* r = heap->get_region(idx);
 44     if (r->is_affiliated() && heap->is_bitmap_slice_committed(r) && !is_bitmap_clear_range(r->bottom(), r->end())) {
 45       return false;
 46     }
 47   }
 48   return true;
 49 }
 50 
 51 bool ShenandoahMarkingContext::is_bitmap_clear_range(const HeapWord* start, const HeapWord* end) const {
 52   if (start < end) {
 53     ShenandoahHeap* heap = ShenandoahHeap::heap();
 54     size_t start_idx = heap->heap_region_index_containing(start);
 55     size_t end_idx = heap->heap_region_index_containing(end - 1);
 56     while (start_idx <= end_idx) {
 57       ShenandoahHeapRegion* r = heap->get_region(start_idx);
 58       if (!heap->is_bitmap_slice_committed(r)) {
 59         return true;
 60       }
 61       start_idx++;
 62     }
 63   }
 64   return _mark_bit_map.is_bitmap_clear_range(start, end);
 65 }
 66 
 67 void ShenandoahMarkingContext::initialize_top_at_mark_start(ShenandoahHeapRegion* r) {
 68   size_t idx = r->index();
 69   HeapWord *bottom = r->bottom();
 70 
 71   _top_at_mark_starts_base[idx] = bottom;
 72   _top_bitmaps[idx] = bottom;
 73 
 74   log_debug(gc)("SMC:initialize_top_at_mark_start for Region " SIZE_FORMAT ", TAMS: " PTR_FORMAT ", TopOfBitMap: " PTR_FORMAT,
 75                 r->index(), p2i(bottom), p2i(r->end()));
 76 }
 77 
 78 HeapWord* ShenandoahMarkingContext::top_bitmap(ShenandoahHeapRegion* r) {
 79   return _top_bitmaps[r->index()];
 80 }
 81 
 82 void ShenandoahMarkingContext::clear_bitmap(ShenandoahHeapRegion* r) {
 83   if (!r->is_affiliated()) {
 84     // Heap iterators include FREE regions, which don't need to be cleared.
 85     // TODO: would be better for certain iterators to not include FREE regions.
 86     return;
 87   }
 88 
 89   HeapWord* bottom = r->bottom();
 90   HeapWord* top_bitmap = _top_bitmaps[r->index()];
 91 
 92   log_debug(gc)("SMC:clear_bitmap for %s Region " SIZE_FORMAT ", top_bitmap: " PTR_FORMAT,
 93                 r->affiliation_name(), r->index(), p2i(top_bitmap));
 94 
 95   if (top_bitmap > bottom) {
 96     _mark_bit_map.clear_range_large(MemRegion(bottom, top_bitmap));
 97     _top_bitmaps[r->index()] = bottom;
 98   }
 99 
100   // TODO: Why is clear_live_data here?
101   r->clear_live_data();
102 
103   assert(is_bitmap_clear_range(bottom, r->end()),
104          "Region " SIZE_FORMAT " should have no marks in bitmap", r->index());
105 }
106 
107 bool ShenandoahMarkingContext::is_complete() {
108   return _is_complete.is_set();
109 }
110 
111 void ShenandoahMarkingContext::mark_complete() {
112   _is_complete.set();
113 }
114 
115 void ShenandoahMarkingContext::mark_incomplete() {
116   _is_complete.unset();
117 }