1 /*
2 * Copyright (c) 2013, 2019, 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 ShenandoahBarrierSet::ShenandoahBarrierSet(ShenandoahHeap* heap) :
46 BarrierSet(make_barrier_set_assembler<ShenandoahBarrierSetAssembler>(),
47 make_barrier_set_c1<ShenandoahBarrierSetC1>(),
48 make_barrier_set_c2<ShenandoahBarrierSetC2>(),
49 NULL /* barrier_set_nmethod */,
50 BarrierSet::FakeRtti(BarrierSet::ShenandoahBarrierSet)),
51 _heap(heap),
52 _satb_mark_queue_buffer_allocator("SATB Buffer Allocator", ShenandoahSATBBufferSize),
53 _satb_mark_queue_set(&_satb_mark_queue_buffer_allocator)
54 {
55 }
56
57 ShenandoahBarrierSetAssembler* ShenandoahBarrierSet::assembler() {
58 BarrierSetAssembler* const bsa = BarrierSet::barrier_set()->barrier_set_assembler();
59 return reinterpret_cast<ShenandoahBarrierSetAssembler*>(bsa);
60 }
61
62 void ShenandoahBarrierSet::print_on(outputStream* st) const {
63 st->print("ShenandoahBarrierSet");
64 }
65
66 bool ShenandoahBarrierSet::is_a(BarrierSet::Name bsn) {
67 return bsn == BarrierSet::ShenandoahBarrierSet;
68 }
69
70 bool ShenandoahBarrierSet::is_aligned(HeapWord* hw) {
71 return true;
72 }
73
74 template <class T>
75 inline void ShenandoahBarrierSet::inline_write_ref_field_pre(T* field, oop new_val) {
76 shenandoah_assert_not_in_cset_loc_except(field, _heap->cancelled_gc());
77 if (_heap->is_concurrent_mark_in_progress()) {
78 T heap_oop = RawAccess<>::oop_load(field);
79 if (!CompressedOops::is_null(heap_oop)) {
80 enqueue(CompressedOops::decode(heap_oop));
81 }
82 }
83 }
84
85 // These are the more general virtual versions.
86 void ShenandoahBarrierSet::write_ref_field_pre_work(oop* field, oop new_val) {
87 inline_write_ref_field_pre(field, new_val);
88 }
89
90 void ShenandoahBarrierSet::write_ref_field_pre_work(narrowOop* field, oop new_val) {
91 inline_write_ref_field_pre(field, new_val);
92 }
93
94 void ShenandoahBarrierSet::write_ref_field_pre_work(void* field, oop new_val) {
95 guarantee(false, "Not needed");
96 }
97
98 void ShenandoahBarrierSet::write_ref_field_work(void* v, oop o, bool release) {
99 shenandoah_assert_not_in_cset_loc_except(v, _heap->cancelled_gc());
100 shenandoah_assert_not_forwarded_except (v, o, o == NULL || _heap->cancelled_gc() || !_heap->is_concurrent_mark_in_progress());
101 shenandoah_assert_not_in_cset_except (v, o, o == NULL || _heap->cancelled_gc() || !_heap->is_concurrent_mark_in_progress());
102 }
103
104 oop ShenandoahBarrierSet::load_reference_barrier_not_null(oop obj) {
105 if (ShenandoahLoadRefBarrier && _heap->has_forwarded_objects()) {
106 return load_reference_barrier_impl(obj);
107 } else {
108 return obj;
109 }
110 }
111
112 oop ShenandoahBarrierSet::load_reference_barrier(oop obj) {
113 if (obj != NULL) {
114 return load_reference_barrier_not_null(obj);
115 } else {
116 return obj;
117 }
118 }
119
120 oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, oop* load_addr) {
121 return load_reference_barrier_mutator_work(obj, load_addr);
122 }
123
124 oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, narrowOop* load_addr) {
125 return load_reference_barrier_mutator_work(obj, load_addr);
126 }
127
128 template <class T>
129 oop ShenandoahBarrierSet::load_reference_barrier_mutator_work(oop obj, T* load_addr) {
130 assert(ShenandoahLoadRefBarrier, "should be enabled");
131 shenandoah_assert_in_cset(load_addr, obj);
132
133 oop fwd = resolve_forwarded_not_null(obj);
134 if (obj == fwd) {
135 assert(_heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL),
136 "evac should be in progress");
137
138 ShenandoahEvacOOMScope oom_evac_scope;
139
140 Thread* thread = Thread::current();
141 oop res_oop = _heap->evacuate_object(obj, thread);
142
143 // Since we are already here and paid the price of getting through runtime call adapters
144 // and acquiring oom-scope, it makes sense to try and evacuate more adjacent objects,
145 // thus amortizing the overhead. For sparsely live heaps, scan costs easily dominate
146 // total assist costs, and can introduce a lot of evacuation latency. This is why we
147 // only scan for _nearest_ N objects, regardless if they are eligible for evac or not.
148 // The scan itself should also avoid touching the non-marked objects below TAMS, because
149 // their metadata (notably, klasses) may be incorrect already.
150
151 size_t max = ShenandoahEvacAssist;
152 if (max > 0) {
153 // Traversal is special: it uses incomplete marking context, because it coalesces evac with mark.
154 // Other code uses complete marking context, because evac happens after the mark.
155 ShenandoahMarkingContext* ctx = _heap->is_concurrent_traversal_in_progress() ?
156 _heap->marking_context() : _heap->complete_marking_context();
157
158 ShenandoahHeapRegion* r = _heap->heap_region_containing(obj);
159 assert(r->is_cset(), "sanity");
160
161 HeapWord* cur = (HeapWord*)obj + obj->size();
162
163 size_t count = 0;
164 while ((cur < r->top()) && ctx->is_marked(oop(cur)) && (count++ < max)) {
165 oop cur_oop = oop(cur);
166 if (cur_oop == resolve_forwarded_not_null(cur_oop)) {
167 _heap->evacuate_object(cur_oop, thread);
168 }
169 cur = cur + cur_oop->size();
170 }
171 }
172
173 fwd = res_oop;
174 }
175
176 if (load_addr != NULL && fwd != obj) {
177 // Since we are here and we know the load address, update the reference.
178 ShenandoahHeap::cas_oop(fwd, load_addr, obj);
179 }
180
181 return fwd;
182 }
183
184 oop ShenandoahBarrierSet::load_reference_barrier_impl(oop obj) {
185 assert(ShenandoahLoadRefBarrier, "should be enabled");
186 if (!CompressedOops::is_null(obj)) {
187 bool evac_in_progress = _heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL);
188 oop fwd = resolve_forwarded_not_null(obj);
189 if (evac_in_progress &&
190 _heap->in_collection_set(obj) &&
191 obj == fwd) {
192 Thread *t = Thread::current();
193 if (t->is_GC_task_thread()) {
194 return _heap->evacuate_object(obj, t);
195 } else {
196 ShenandoahEvacOOMScope oom_evac_scope;
197 return _heap->evacuate_object(obj, t);
198 }
199 } else {
200 return fwd;
201 }
202 } else {
203 return obj;
204 }
205 }
206
207 void ShenandoahBarrierSet::storeval_barrier(oop obj) {
208 if (ShenandoahStoreValEnqueueBarrier && !CompressedOops::is_null(obj) && _heap->is_concurrent_traversal_in_progress()) {
209 enqueue(obj);
210 }
211 }
212
213 void ShenandoahBarrierSet::keep_alive_barrier(oop obj) {
214 if (ShenandoahKeepAliveBarrier && _heap->is_concurrent_mark_in_progress()) {
215 enqueue(obj);
216 }
217 }
218
219 void ShenandoahBarrierSet::enqueue(oop obj) {
220 shenandoah_assert_not_forwarded_if(NULL, obj, _heap->is_concurrent_traversal_in_progress());
221 assert(_satb_mark_queue_set.is_active(), "only get here when SATB active");
222
223 // Filter marked objects before hitting the SATB queues. The same predicate would
224 // be used by SATBMQ::filter to eliminate already marked objects downstream, but
225 // filtering here helps to avoid wasteful SATB queueing work to begin with.
226 if (!_heap->requires_marking<false>(obj)) return;
227
228 ShenandoahThreadLocalData::satb_mark_queue(Thread::current()).enqueue_known_active(obj);
229 }
230
231 void ShenandoahBarrierSet::on_thread_create(Thread* thread) {
232 // Create thread local data
233 ShenandoahThreadLocalData::create(thread);
234 }
235
236 void ShenandoahBarrierSet::on_thread_destroy(Thread* thread) {
237 // Destroy thread local data
238 ShenandoahThreadLocalData::destroy(thread);
239 }
240
241 void ShenandoahBarrierSet::on_thread_attach(Thread *thread) {
242 assert(!thread->is_Java_thread() || !SafepointSynchronize::is_at_safepoint(),
243 "We should not be at a safepoint");
244 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
245 assert(!queue.is_active(), "SATB queue should not be active");
246 assert( queue.is_empty(), "SATB queue should be empty");
247 queue.set_active(_satb_mark_queue_set.is_active());
248 if (thread->is_Java_thread()) {
249 ShenandoahThreadLocalData::set_gc_state(thread, _heap->gc_state());
250 ShenandoahThreadLocalData::initialize_gclab(thread);
251 }
252 }
253
254 void ShenandoahBarrierSet::on_thread_detach(Thread *thread) {
255 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
256 queue.flush();
257 if (thread->is_Java_thread()) {
258 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
259 if (gclab != NULL) {
260 gclab->retire();
261 }
262 }
263 }
264
265 oop ShenandoahBarrierSet::load_reference_barrier_native(oop obj, oop* load_addr) {
266 return load_reference_barrier_native_impl(obj, load_addr);
267 }
268
269 oop ShenandoahBarrierSet::load_reference_barrier_native(oop obj, narrowOop* load_addr) {
270 // Assumption: narrow oop version should not be used anywhere.
271 ShouldNotReachHere();
272 return NULL;
273 }
274
275 template <class T>
276 oop ShenandoahBarrierSet::load_reference_barrier_native_impl(oop obj, T* load_addr) {
277 if (CompressedOops::is_null(obj)) {
278 return NULL;
279 }
280
281 ShenandoahMarkingContext* const marking_context = _heap->marking_context();
282 if (_heap->is_evacuation_in_progress() && !marking_context->is_marked(obj)) {
283 Thread* thr = Thread::current();
284 if (thr->is_Java_thread()) {
285 return NULL;
286 } else {
287 return obj;
288 }
289 }
290
291 oop fwd = load_reference_barrier_not_null(obj);
292 if (load_addr != NULL && fwd != obj) {
293 // Since we are here and we know the load address, update the reference.
294 ShenandoahHeap::cas_oop(fwd, load_addr, obj);
295 }
296
297 return fwd;
298 }
299
300 void ShenandoahBarrierSet::clone_barrier_runtime(oop src) {
301 if (_heap->has_forwarded_objects()) {
302 clone_barrier(src);
303 }
304 }
305