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/shenandoahBarrierSetAssembler.hpp"
28 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
29 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
30 #include "gc/shenandoah/shenandoahHeuristics.hpp"
31 #include "gc/shenandoah/shenandoahTraversalGC.hpp"
32 #include "memory/iterator.inline.hpp"
33 #include "runtime/interfaceSupport.inline.hpp"
34 #ifdef COMPILER1
35 #include "gc/shenandoah/c1/shenandoahBarrierSetC1.hpp"
36 #endif
37 #ifdef COMPILER2
38 #include "gc/shenandoah/c2/shenandoahBarrierSetC2.hpp"
39 #endif
40
41 class ShenandoahBarrierSetC1;
42 class ShenandoahBarrierSetC2;
43
44 template <bool STOREVAL_WRITE_BARRIER>
45 class ShenandoahUpdateRefsForOopClosure: public BasicOopIterateClosure {
46 private:
47 ShenandoahHeap* _heap;
48 ShenandoahBarrierSet* _bs;
49
50 template <class T>
51 inline void do_oop_work(T* p) {
52 oop o;
53 if (STOREVAL_WRITE_BARRIER) {
54 o = _heap->evac_update_with_forwarded(p);
55 if (!CompressedOops::is_null(o)) {
56 _bs->enqueue(o);
57 }
58 } else {
59 _heap->maybe_update_with_forwarded(p);
60 }
61 }
62 public:
63 ShenandoahUpdateRefsForOopClosure() : _heap(ShenandoahHeap::heap()), _bs(ShenandoahBarrierSet::barrier_set()) {
64 assert(UseShenandoahGC && ShenandoahCloneBarrier, "should be enabled");
65 }
66
67 virtual void do_oop(oop* p) { do_oop_work(p); }
68 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
69 };
70
71 ShenandoahBarrierSet::ShenandoahBarrierSet(ShenandoahHeap* heap) :
72 BarrierSet(make_barrier_set_assembler<ShenandoahBarrierSetAssembler>(),
73 make_barrier_set_c1<ShenandoahBarrierSetC1>(),
74 make_barrier_set_c2<ShenandoahBarrierSetC2>(),
75 NULL /* barrier_set_nmethod */,
76 BarrierSet::FakeRtti(BarrierSet::ShenandoahBarrierSet)),
77 _heap(heap),
78 _satb_mark_queue_set()
79 {
80 }
81
82 ShenandoahBarrierSetAssembler* ShenandoahBarrierSet::assembler() {
83 BarrierSetAssembler* const bsa = BarrierSet::barrier_set()->barrier_set_assembler();
84 return reinterpret_cast<ShenandoahBarrierSetAssembler*>(bsa);
85 }
86
87 void ShenandoahBarrierSet::print_on(outputStream* st) const {
88 st->print("ShenandoahBarrierSet");
89 }
90
91 bool ShenandoahBarrierSet::is_a(BarrierSet::Name bsn) {
92 return bsn == BarrierSet::ShenandoahBarrierSet;
93 }
94
95 bool ShenandoahBarrierSet::is_aligned(HeapWord* hw) {
96 return true;
97 }
98
99 template <class T, bool STOREVAL_WRITE_BARRIER>
100 void ShenandoahBarrierSet::write_ref_array_loop(HeapWord* start, size_t count) {
101 assert(UseShenandoahGC && ShenandoahCloneBarrier, "should be enabled");
102 ShenandoahUpdateRefsForOopClosure<STOREVAL_WRITE_BARRIER> cl;
103 T* dst = (T*) start;
104 for (size_t i = 0; i < count; i++) {
105 cl.do_oop(dst++);
106 }
107 }
108
109 void ShenandoahBarrierSet::write_ref_array(HeapWord* start, size_t count) {
110 assert(UseShenandoahGC, "should be enabled");
111 if (count == 0) return;
112 if (!ShenandoahCloneBarrier) return;
113
114 if (!need_update_refs_barrier()) return;
115
116 if (_heap->is_concurrent_traversal_in_progress()) {
117 ShenandoahEvacOOMScope oom_evac_scope;
118 if (UseCompressedOops) {
119 write_ref_array_loop<narrowOop, /* wb = */ true>(start, count);
120 } else {
121 write_ref_array_loop<oop, /* wb = */ true>(start, count);
122 }
123 } else {
124 if (UseCompressedOops) {
125 write_ref_array_loop<narrowOop, /* wb = */ false>(start, count);
126 } else {
127 write_ref_array_loop<oop, /* wb = */ false>(start, count);
128 }
129 }
130 }
131
132 template <class T>
133 void ShenandoahBarrierSet::write_ref_array_pre_work(T* dst, size_t count) {
134 shenandoah_assert_not_in_cset_loc_except(dst, _heap->cancelled_gc());
135 assert(ShenandoahThreadLocalData::satb_mark_queue(Thread::current()).is_active(), "Shouldn't be here otherwise");
136 assert(ShenandoahSATBBarrier, "Shouldn't be here otherwise");
137 assert(count > 0, "Should have been filtered before");
138
139 Thread* thread = Thread::current();
140 ShenandoahMarkingContext* ctx = _heap->marking_context();
141 bool has_forwarded = _heap->has_forwarded_objects();
142 T* elem_ptr = dst;
143 for (size_t i = 0; i < count; i++, elem_ptr++) {
144 T heap_oop = RawAccess<>::oop_load(elem_ptr);
145 if (!CompressedOops::is_null(heap_oop)) {
146 oop obj = CompressedOops::decode_not_null(heap_oop);
147 if (has_forwarded) {
148 obj = resolve_forwarded_not_null(obj);
149 }
150 if (!ctx->is_marked(obj)) {
151 ShenandoahThreadLocalData::satb_mark_queue(thread).enqueue_known_active(obj);
152 }
153 }
154 }
155 }
156
157 void ShenandoahBarrierSet::write_ref_array_pre(oop* dst, size_t count, bool dest_uninitialized) {
158 if (! dest_uninitialized) {
159 write_ref_array_pre_work(dst, count);
160 }
161 }
162
163 void ShenandoahBarrierSet::write_ref_array_pre(narrowOop* dst, size_t count, bool dest_uninitialized) {
164 if (! dest_uninitialized) {
165 write_ref_array_pre_work(dst, count);
166 }
167 }
168
169 template <class T>
170 inline void ShenandoahBarrierSet::inline_write_ref_field_pre(T* field, oop new_val) {
171 shenandoah_assert_not_in_cset_loc_except(field, _heap->cancelled_gc());
172 if (_heap->is_concurrent_mark_in_progress()) {
173 T heap_oop = RawAccess<>::oop_load(field);
174 if (!CompressedOops::is_null(heap_oop)) {
175 enqueue(CompressedOops::decode(heap_oop));
176 }
177 }
178 }
179
180 // These are the more general virtual versions.
181 void ShenandoahBarrierSet::write_ref_field_pre_work(oop* field, oop new_val) {
182 inline_write_ref_field_pre(field, new_val);
183 }
184
185 void ShenandoahBarrierSet::write_ref_field_pre_work(narrowOop* field, oop new_val) {
186 inline_write_ref_field_pre(field, new_val);
187 }
188
189 void ShenandoahBarrierSet::write_ref_field_pre_work(void* field, oop new_val) {
190 guarantee(false, "Not needed");
191 }
192
193 void ShenandoahBarrierSet::write_ref_field_work(void* v, oop o, bool release) {
194 shenandoah_assert_not_in_cset_loc_except(v, _heap->cancelled_gc());
195 shenandoah_assert_not_forwarded_except (v, o, o == NULL || _heap->cancelled_gc() || !_heap->is_concurrent_mark_in_progress());
196 shenandoah_assert_not_in_cset_except (v, o, o == NULL || _heap->cancelled_gc() || !_heap->is_concurrent_mark_in_progress());
197 }
198
199 void ShenandoahBarrierSet::write_region(MemRegion mr) {
200 assert(UseShenandoahGC, "should be enabled");
201 if (!ShenandoahCloneBarrier) return;
202 if (! need_update_refs_barrier()) return;
203
204 // This is called for cloning an object (see jvm.cpp) after the clone
205 // has been made. We are not interested in any 'previous value' because
206 // it would be NULL in any case. But we *are* interested in any oop*
207 // that potentially need to be updated.
208
209 oop obj = oop(mr.start());
210 shenandoah_assert_correct(NULL, obj);
211 if (_heap->is_concurrent_traversal_in_progress()) {
212 ShenandoahEvacOOMScope oom_evac_scope;
213 ShenandoahUpdateRefsForOopClosure</* wb = */ true> cl;
214 obj->oop_iterate(&cl);
215 } else {
216 ShenandoahUpdateRefsForOopClosure</* wb = */ false> cl;
217 obj->oop_iterate(&cl);
218 }
219 }
220
221 oop ShenandoahBarrierSet::load_reference_barrier_not_null(oop obj) {
222 if (ShenandoahLoadRefBarrier && _heap->has_forwarded_objects()) {
223 return load_reference_barrier_impl(obj);
224 } else {
225 return obj;
226 }
227 }
228
229 oop ShenandoahBarrierSet::load_reference_barrier(oop obj) {
230 if (obj != NULL) {
231 return load_reference_barrier_not_null(obj);
232 } else {
233 return obj;
234 }
235 }
236
237
238 oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj) {
239 assert(ShenandoahLoadRefBarrier, "should be enabled");
240 assert(_heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL), "evac should be in progress");
241 shenandoah_assert_in_cset(NULL, obj);
242
243 oop fwd = resolve_forwarded_not_null(obj);
244 if (oopDesc::equals_raw(obj, fwd)) {
245 ShenandoahEvacOOMScope oom_evac_scope;
246
247 Thread* thread = Thread::current();
248 oop res_oop = _heap->evacuate_object(obj, thread);
249
250 // Since we are already here and paid the price of getting through runtime call adapters
251 // and acquiring oom-scope, it makes sense to try and evacuate more adjacent objects,
252 // thus amortizing the overhead. For sparsely live heaps, scan costs easily dominate
253 // total assist costs, and can introduce a lot of evacuation latency. This is why we
254 // only scan for _nearest_ N objects, regardless if they are eligible for evac or not.
255 // The scan itself should also avoid touching the non-marked objects below TAMS, because
256 // their metadata (notably, klasses) may be incorrect already.
257
258 size_t max = ShenandoahEvacAssist;
259 if (max > 0) {
260 // Traversal is special: it uses incomplete marking context, because it coalesces evac with mark.
261 // Other code uses complete marking context, because evac happens after the mark.
262 ShenandoahMarkingContext* ctx = _heap->is_concurrent_traversal_in_progress() ?
263 _heap->marking_context() : _heap->complete_marking_context();
264
265 ShenandoahHeapRegion* r = _heap->heap_region_containing(obj);
266 assert(r->is_cset(), "sanity");
267
268 HeapWord* cur = (HeapWord*)obj + obj->size() + ShenandoahBrooksPointer::word_size();
269
270 size_t count = 0;
271 while ((cur < r->top()) && ctx->is_marked(oop(cur)) && (count++ < max)) {
272 oop cur_oop = oop(cur);
273 if (oopDesc::equals_raw(cur_oop, resolve_forwarded_not_null(cur_oop))) {
274 _heap->evacuate_object(cur_oop, thread);
275 }
276 cur = cur + cur_oop->size() + ShenandoahBrooksPointer::word_size();
277 }
278 }
279
280 return res_oop;
281 }
282 return fwd;
283 }
284
285 oop ShenandoahBarrierSet::load_reference_barrier_impl(oop obj) {
286 assert(ShenandoahLoadRefBarrier, "should be enabled");
287 if (!CompressedOops::is_null(obj)) {
288 bool evac_in_progress = _heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL);
289 oop fwd = resolve_forwarded_not_null(obj);
290 if (evac_in_progress &&
291 _heap->in_collection_set(obj) &&
292 oopDesc::equals_raw(obj, fwd)) {
293 Thread *t = Thread::current();
294 if (t->is_GC_task_thread()) {
295 return _heap->evacuate_object(obj, t);
296 } else {
297 ShenandoahEvacOOMScope oom_evac_scope;
298 return _heap->evacuate_object(obj, t);
299 }
300 } else {
301 return fwd;
302 }
303 } else {
304 return obj;
305 }
306 }
307
308 void ShenandoahBarrierSet::storeval_barrier(oop obj) {
309 if (ShenandoahStoreValEnqueueBarrier && !CompressedOops::is_null(obj) && _heap->is_concurrent_traversal_in_progress()) {
310 enqueue(obj);
311 }
312 }
313
314 void ShenandoahBarrierSet::keep_alive_barrier(oop obj) {
315 if (ShenandoahKeepAliveBarrier && _heap->is_concurrent_mark_in_progress()) {
316 enqueue(obj);
317 }
318 }
319
320 void ShenandoahBarrierSet::enqueue(oop obj) {
321 shenandoah_assert_not_forwarded_if(NULL, obj, _heap->is_concurrent_traversal_in_progress());
322 assert(_satb_mark_queue_set.is_active(), "only get here when SATB active");
323
324 // Filter marked objects before hitting the SATB queues. The same predicate would
325 // be used by SATBMQ::filter to eliminate already marked objects downstream, but
326 // filtering here helps to avoid wasteful SATB queueing work to begin with.
327 if (!_heap->requires_marking<false>(obj)) return;
328
329 ShenandoahThreadLocalData::satb_mark_queue(Thread::current()).enqueue_known_active(obj);
330 }
331
332 void ShenandoahBarrierSet::on_thread_create(Thread* thread) {
333 // Create thread local data
334 ShenandoahThreadLocalData::create(thread);
335 }
336
337 void ShenandoahBarrierSet::on_thread_destroy(Thread* thread) {
338 // Destroy thread local data
339 ShenandoahThreadLocalData::destroy(thread);
340 }
341
342 void ShenandoahBarrierSet::on_thread_attach(Thread *thread) {
343 assert(!thread->is_Java_thread() || !SafepointSynchronize::is_at_safepoint(),
344 "We should not be at a safepoint");
345 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
346 assert(!queue.is_active(), "SATB queue should not be active");
347 assert( queue.is_empty(), "SATB queue should be empty");
348 queue.set_active(_satb_mark_queue_set.is_active());
349 if (thread->is_Java_thread()) {
350 ShenandoahThreadLocalData::set_gc_state(thread, _heap->gc_state());
351 ShenandoahThreadLocalData::initialize_gclab(thread);
352 }
353 }
354
355 void ShenandoahBarrierSet::on_thread_detach(Thread *thread) {
356 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
357 queue.flush();
358 if (thread->is_Java_thread()) {
359 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
360 if (gclab != NULL) {
361 gclab->retire();
362 }
363 }
364 }