1 /*
2 * Copyright (c) 2013, 2022, 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 "gc/shared/barrierSetNMethod.hpp"
27 #include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"
28 #include "gc/shenandoah/shenandoahBarrierSetClone.inline.hpp"
29 #include "gc/shenandoah/shenandoahBarrierSetNMethod.hpp"
30 #include "gc/shenandoah/shenandoahBarrierSetStackChunk.hpp"
31 #include "gc/shenandoah/shenandoahCardTable.hpp"
32 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
33 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
34 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
35 #include "gc/shenandoah/shenandoahStackWatermark.hpp"
36 #ifdef COMPILER1
37 #include "gc/shenandoah/c1/shenandoahBarrierSetC1.hpp"
38 #endif
39 #ifdef COMPILER2
40 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
41 #endif
42
43 class ShenandoahBarrierSetC1;
44 class ShenandoahBarrierSetC2;
45
46 ShenandoahBarrierSet::ShenandoahBarrierSet(ShenandoahHeap* heap, MemRegion heap_region) :
47 BarrierSet(make_barrier_set_assembler<ShenandoahBarrierSetAssembler>(),
48 make_barrier_set_c1<ShenandoahBarrierSetC1>(),
49 make_barrier_set_c2<ShenandoahBarrierSetC2>(),
50 new ShenandoahBarrierSetNMethod(heap),
51 new ShenandoahBarrierSetStackChunk(),
52 BarrierSet::FakeRtti(BarrierSet::ShenandoahBarrierSet)),
53 _heap(heap),
54 _card_table(nullptr),
55 _satb_mark_queue_buffer_allocator("SATB Buffer Allocator", ShenandoahSATBBufferSize),
56 _satb_mark_queue_set(&_satb_mark_queue_buffer_allocator)
57 {
58 if (ShenandoahCardBarrier) {
59 _card_table = new ShenandoahCardTable(heap_region);
60 _card_table->initialize();
61 }
62 }
63
64 ShenandoahBarrierSetAssembler* ShenandoahBarrierSet::assembler() {
65 BarrierSetAssembler* const bsa = BarrierSet::barrier_set()->barrier_set_assembler();
66 return reinterpret_cast<ShenandoahBarrierSetAssembler*>(bsa);
67 }
68
69 void ShenandoahBarrierSet::print_on(outputStream* st) const {
70 st->print("ShenandoahBarrierSet");
71 }
72
73 bool ShenandoahBarrierSet::need_load_reference_barrier(DecoratorSet decorators, BasicType type) {
74 if (!ShenandoahLoadRefBarrier) return false;
75 return is_reference_type(type);
76 }
77
78 bool ShenandoahBarrierSet::need_keep_alive_barrier(DecoratorSet decorators, BasicType type) {
79 if (!ShenandoahSATBBarrier) return false;
80 if (!is_reference_type(type)) return false;
81 bool keep_alive = (decorators & AS_NO_KEEPALIVE) == 0;
82 bool unknown = (decorators & ON_UNKNOWN_OOP_REF) != 0;
83 bool on_weak_ref = (decorators & (ON_WEAK_OOP_REF | ON_PHANTOM_OOP_REF)) != 0;
84 return (on_weak_ref || unknown) && keep_alive;
85 }
86
87 bool ShenandoahBarrierSet::need_satb_barrier(DecoratorSet decorators, BasicType type) {
88 if (!ShenandoahSATBBarrier) return false;
89 if (!is_reference_type(type)) return false;
90 bool as_normal = (decorators & AS_NORMAL) != 0;
91 bool dest_uninitialized = (decorators & IS_DEST_UNINITIALIZED) != 0;
92 return as_normal && !dest_uninitialized;
93 }
94
95 bool ShenandoahBarrierSet::need_card_barrier(DecoratorSet decorators, BasicType type) {
96 if (!ShenandoahCardBarrier) return false;
97 if (!is_reference_type(type)) return false;
98 bool in_heap = (decorators & IN_HEAP) != 0;
99 return in_heap;
100 }
101
102 void ShenandoahBarrierSet::on_slowpath_allocation_exit(JavaThread* thread, oop new_obj) {
103 #if COMPILER2_OR_JVMCI
104 if (ReduceInitialCardMarks && ShenandoahCardBarrier && !ShenandoahHeap::heap()->is_in_young(new_obj)) {
105 log_debug(gc)("Newly allocated object (" PTR_FORMAT ") is not in the young generation", p2i(new_obj));
106 // This can happen when an object is newly allocated, but we come to a safepoint before returning
107 // the object. If the safepoint runs a degenerated cycle that is upgraded to a full GC, this object
108 // will have survived two GC cycles. If the tenuring age is very low (1), this object may be promoted.
109 // In this case, we have an allocated object, but it has received no stores yet. If card marking barriers
110 // have been elided, we could end up with an object in old holding pointers to young that won't be in
111 // the remembered set. The solution here is conservative, but this problem should be rare, and it will
112 // correct itself on subsequent cycles when the remembered set is updated.
113 ShenandoahGenerationalHeap::heap()->old_generation()->card_scan()->mark_range_as_dirty(
114 cast_from_oop<HeapWord*>(new_obj), new_obj->size()
115 );
116 }
117 #endif // COMPILER2_OR_JVMCI
118 }
119
120 void ShenandoahBarrierSet::on_thread_create(Thread* thread) {
121 // Create thread local data
122 ShenandoahThreadLocalData::create(thread);
123 }
124
125 void ShenandoahBarrierSet::on_thread_destroy(Thread* thread) {
126 // Destroy thread local data
127 ShenandoahThreadLocalData::destroy(thread);
128 }
129
130 void ShenandoahBarrierSet::on_thread_attach(Thread *thread) {
131 assert(!thread->is_Java_thread() || !SafepointSynchronize::is_at_safepoint(),
132 "We should not be at a safepoint");
133 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
134 assert(!queue.is_active(), "SATB queue should not be active");
135 assert(queue.buffer() == nullptr, "SATB queue should not have a buffer");
136 assert(queue.index() == 0, "SATB queue index should be zero");
137 queue.set_active(_satb_mark_queue_set.is_active());
138
139 if (ShenandoahCardBarrier) {
140 // Every thread always have a pointer to the _current_ _write_ version of the card table.
141 // The JIT'ed code will use this address (+card entry offset) to mark the card as dirty.
142 ShenandoahThreadLocalData::set_card_table(thread, _card_table->write_byte_map_base());
143 }
144 ShenandoahThreadLocalData::set_gc_state(thread, _heap->gc_state());
145
146 if (thread->is_Java_thread()) {
147 ShenandoahThreadLocalData::initialize_gclab(thread);
148
149 BarrierSetNMethod* bs_nm = barrier_set_nmethod();
150 thread->set_nmethod_disarmed_guard_value(bs_nm->disarmed_guard_value());
151
152 if (ShenandoahStackWatermarkBarrier) {
153 JavaThread* const jt = JavaThread::cast(thread);
154 StackWatermark* const watermark = new ShenandoahStackWatermark(jt);
155 StackWatermarkSet::add_watermark(jt, watermark);
156 }
157 }
158 }
159
160 void ShenandoahBarrierSet::on_thread_detach(Thread *thread) {
161 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
162 _satb_mark_queue_set.flush_queue(queue);
163 if (thread->is_Java_thread()) {
164 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
165 if (gclab != nullptr) {
166 gclab->retire();
167 }
168
169 PLAB* plab = ShenandoahThreadLocalData::plab(thread);
170 if (plab != nullptr) {
171 // This will assert if plab is not null in non-generational mode
172 ShenandoahGenerationalHeap::heap()->retire_plab(plab);
173 }
174
175 // SATB protocol requires to keep alive reachable oops from roots at the beginning of GC
176 if (ShenandoahStackWatermarkBarrier) {
177 if (_heap->is_concurrent_mark_in_progress()) {
178 ShenandoahKeepAliveClosure oops;
179 StackWatermarkSet::finish_processing(JavaThread::cast(thread), &oops, StackWatermarkKind::gc);
180 } else if (_heap->is_concurrent_weak_root_in_progress() && _heap->is_evacuation_in_progress()) {
181 ShenandoahContextEvacuateUpdateRootsClosure oops;
182 StackWatermarkSet::finish_processing(JavaThread::cast(thread), &oops, StackWatermarkKind::gc);
183 }
184 }
185 }
186 }
187
188 void ShenandoahBarrierSet::clone_barrier_runtime(oop src) {
189 if (_heap->has_forwarded_objects()) {
190 clone_barrier(src);
191 }
192 }
193
194 void ShenandoahBarrierSet::write_ref_array(HeapWord* start, size_t count) {
195 assert(ShenandoahCardBarrier, "Should have been checked by caller");
196
197 HeapWord* end = (HeapWord*)((char*) start + (count * heapOopSize));
198 // In the case of compressed oops, start and end may potentially be misaligned;
199 // so we need to conservatively align the first downward (this is not
200 // strictly necessary for current uses, but a case of good hygiene and,
201 // if you will, aesthetics) and the second upward (this is essential for
202 // current uses) to a HeapWord boundary, so we mark all cards overlapping
203 // this write.
204 HeapWord* aligned_start = align_down(start, HeapWordSize);
205 HeapWord* aligned_end = align_up (end, HeapWordSize);
206 // If compressed oops were not being used, these should already be aligned
207 assert(UseCompressedOops || (aligned_start == start && aligned_end == end),
208 "Expected heap word alignment of start and end");
209 _heap->old_generation()->card_scan()->mark_range_as_dirty(aligned_start, (aligned_end - aligned_start));
210 }
211