1 /*
2 * Copyright (c) 2013, 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #include "precompiled.hpp"
25 #include "gc/shenandoah/shenandoahAsserts.hpp"
26 #include "gc/shenandoah/shenandoahBarrierSet.hpp"
27 #include "gc/shenandoah/shenandoahBarrierSetClone.inline.hpp"
28 #include "gc/shenandoah/shenandoahBarrierSetAssembler.hpp"
29 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
30 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
31 #include "gc/shenandoah/shenandoahHeuristics.hpp"
32 #include "gc/shenandoah/shenandoahTraversalGC.hpp"
33 #include "memory/iterator.inline.hpp"
34 #include "runtime/interfaceSupport.inline.hpp"
35 #ifdef COMPILER1
36 #include "gc/shenandoah/c1/shenandoahBarrierSetC1.hpp"
37 #endif
38 #ifdef COMPILER2
39 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
40 #endif
41
42 class ShenandoahBarrierSetC1;
43 class ShenandoahBarrierSetC2;
44
45 ShenandoahSATBMarkQueueSet ShenandoahBarrierSet::_satb_mark_queue_set;
46
47 ShenandoahBarrierSet::ShenandoahBarrierSet(ShenandoahHeap* heap) :
48 BarrierSet(make_barrier_set_assembler<ShenandoahBarrierSetAssembler>(),
49 make_barrier_set_c1<ShenandoahBarrierSetC1>(),
50 make_barrier_set_c2<ShenandoahBarrierSetC2>(),
51 BarrierSet::FakeRtti(BarrierSet::ShenandoahBarrierSet)),
52 _heap(heap)
53 {
54 }
55
56 ShenandoahBarrierSetAssembler* ShenandoahBarrierSet::assembler() {
57 BarrierSetAssembler* const bsa = BarrierSet::barrier_set()->barrier_set_assembler();
58 return reinterpret_cast<ShenandoahBarrierSetAssembler*>(bsa);
59 }
60
61 void ShenandoahBarrierSet::print_on(outputStream* st) const {
62 st->print("ShenandoahBarrierSet");
63 }
64
65 bool ShenandoahBarrierSet::is_a(BarrierSet::Name bsn) {
66 return bsn == BarrierSet::ShenandoahBarrierSet;
67 }
68
69 bool ShenandoahBarrierSet::is_aligned(HeapWord* hw) {
70 return true;
71 }
72
73 bool ShenandoahBarrierSet::need_load_reference_barrier(DecoratorSet decorators, BasicType type) {
74 if (!ShenandoahLoadRefBarrier) return false;
75 // Only needed for references
76 return is_reference_type(type);
77 }
78
79 bool ShenandoahBarrierSet::need_keep_alive_barrier(DecoratorSet decorators,BasicType type) {
80 if (!ShenandoahKeepAliveBarrier) return false;
81 // Only needed for references
82 if (!is_reference_type(type)) return false;
83
84 bool keep_alive = (decorators & AS_NO_KEEPALIVE) == 0;
85 bool unknown = (decorators & ON_UNKNOWN_OOP_REF) != 0;
86 bool is_traversal_mode = ShenandoahHeap::heap()->is_traversal_mode();
87 bool on_weak_ref = (decorators & (ON_WEAK_OOP_REF | ON_PHANTOM_OOP_REF)) != 0;
88 return (on_weak_ref || unknown) && (keep_alive || is_traversal_mode);
89 }
90
91 oop ShenandoahBarrierSet::load_reference_barrier_not_null(oop obj) {
92 if (ShenandoahLoadRefBarrier && _heap->has_forwarded_objects()) {
93 return load_reference_barrier_impl(obj);
94 } else {
95 return obj;
96 }
97 }
98
99 oop ShenandoahBarrierSet::load_reference_barrier(oop obj) {
100 if (obj != NULL) {
101 return load_reference_barrier_not_null(obj);
102 } else {
103 return obj;
104 }
105 }
106
107 oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, oop* load_addr) {
108 return load_reference_barrier_mutator_work(obj, load_addr);
109 }
110
111 oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, narrowOop* load_addr) {
112 return load_reference_barrier_mutator_work(obj, load_addr);
113 }
114
115 template <class T>
116 oop ShenandoahBarrierSet::load_reference_barrier_mutator_work(oop obj, T* load_addr) {
117 assert(ShenandoahLoadRefBarrier, "should be enabled");
118 shenandoah_assert_in_cset(load_addr, obj);
119
120 oop fwd = resolve_forwarded_not_null(obj);
121 if (obj == fwd) {
122 assert(_heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL),
123 "evac should be in progress");
124
125 ShenandoahEvacOOMScope oom_evac_scope;
126
127 Thread* thread = Thread::current();
128 oop res_oop = _heap->evacuate_object(obj, thread);
129
130 // Since we are already here and paid the price of getting through runtime call adapters
131 // and acquiring oom-scope, it makes sense to try and evacuate more adjacent objects,
132 // thus amortizing the overhead. For sparsely live heaps, scan costs easily dominate
133 // total assist costs, and can introduce a lot of evacuation latency. This is why we
134 // only scan for _nearest_ N objects, regardless if they are eligible for evac or not.
135 // The scan itself should also avoid touching the non-marked objects below TAMS, because
136 // their metadata (notably, klasses) may be incorrect already.
137
138 size_t max = ShenandoahEvacAssist;
139 if (max > 0) {
140 // Traversal is special: it uses incomplete marking context, because it coalesces evac with mark.
141 // Other code uses complete marking context, because evac happens after the mark.
142 ShenandoahMarkingContext* ctx = _heap->is_concurrent_traversal_in_progress() ?
143 _heap->marking_context() : _heap->complete_marking_context();
144
145 ShenandoahHeapRegion* r = _heap->heap_region_containing(obj);
146 assert(r->is_cset(), "sanity");
147
148 HeapWord* cur = (HeapWord*)obj + obj->size();
149
150 size_t count = 0;
151 while ((cur < r->top()) && ctx->is_marked(oop(cur)) && (count++ < max)) {
152 oop cur_oop = oop(cur);
153 if (cur_oop == resolve_forwarded_not_null(cur_oop)) {
154 _heap->evacuate_object(cur_oop, thread);
155 }
156 cur = cur + cur_oop->size();
157 }
158 }
159
160 fwd = res_oop;
161 }
162
163 if (load_addr != NULL && fwd != obj) {
164 // Since we are here and we know the load address, update the reference.
165 ShenandoahHeap::cas_oop(fwd, load_addr, obj);
166 }
167
168 return fwd;
169 }
170
171 oop ShenandoahBarrierSet::load_reference_barrier_impl(oop obj) {
172 assert(ShenandoahLoadRefBarrier, "should be enabled");
173 if (!CompressedOops::is_null(obj)) {
174 bool evac_in_progress = _heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL);
175 oop fwd = resolve_forwarded_not_null(obj);
176 if (evac_in_progress &&
177 _heap->in_collection_set(obj) &&
178 obj == fwd) {
179 Thread *t = Thread::current();
180 ShenandoahEvacOOMScope oom_evac_scope;
181 return _heap->evacuate_object(obj, t);
182 } else {
183 return fwd;
184 }
185 } else {
186 return obj;
187 }
188 }
189
190 void ShenandoahBarrierSet::on_thread_create(Thread* thread) {
191 // Create thread local data
192 ShenandoahThreadLocalData::create(thread);
193 }
194
195 void ShenandoahBarrierSet::on_thread_destroy(Thread* thread) {
196 // Destroy thread local data
197 ShenandoahThreadLocalData::destroy(thread);
198 }
199
200 void ShenandoahBarrierSet::on_thread_attach(JavaThread* thread) {
201 assert(!SafepointSynchronize::is_at_safepoint(), "We should not be at a safepoint");
202 assert(!ShenandoahThreadLocalData::satb_mark_queue(thread).is_active(), "SATB queue should not be active");
203 assert(ShenandoahThreadLocalData::satb_mark_queue(thread).is_empty(), "SATB queue should be empty");
204 if (ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
205 ShenandoahThreadLocalData::satb_mark_queue(thread).set_active(true);
206 }
207 ShenandoahThreadLocalData::set_gc_state(thread, _heap->gc_state());
208 ShenandoahThreadLocalData::initialize_gclab(thread);
209 }
210
211 void ShenandoahBarrierSet::on_thread_detach(JavaThread* thread) {
212 ShenandoahThreadLocalData::satb_mark_queue(thread).flush();
213 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
214 if (gclab != NULL) {
215 gclab->retire();
216 }
217 }
218
219 void ShenandoahBarrierSet::clone_barrier_runtime(oop src) {
220 if (_heap->has_forwarded_objects()) {
221 clone_barrier(src);
222 }
223 }
224