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/shenandoahConcurrentRoots.hpp"
31 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
32 #include "gc/shenandoah/shenandoahHeuristics.hpp"
33 #include "gc/shenandoah/shenandoahTraversalGC.hpp"
34 #include "memory/iterator.inline.hpp"
35 #include "runtime/interfaceSupport.inline.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) :
47 BarrierSet(make_barrier_set_assembler<ShenandoahBarrierSetAssembler>(),
48 make_barrier_set_c1<ShenandoahBarrierSetC1>(),
49 make_barrier_set_c2<ShenandoahBarrierSetC2>(),
50 NULL /* barrier_set_nmethod */,
51 BarrierSet::FakeRtti(BarrierSet::ShenandoahBarrierSet)),
52 _heap(heap),
53 _satb_mark_queue_buffer_allocator("SATB Buffer Allocator", ShenandoahSATBBufferSize),
54 _satb_mark_queue_set(&_satb_mark_queue_buffer_allocator)
55 {
56 }
57
58 ShenandoahBarrierSetAssembler* ShenandoahBarrierSet::assembler() {
59 BarrierSetAssembler* const bsa = BarrierSet::barrier_set()->barrier_set_assembler();
60 return reinterpret_cast<ShenandoahBarrierSetAssembler*>(bsa);
61 }
62
63 void ShenandoahBarrierSet::print_on(outputStream* st) const {
64 st->print("ShenandoahBarrierSet");
65 }
66
67 bool ShenandoahBarrierSet::is_a(BarrierSet::Name bsn) {
68 return bsn == BarrierSet::ShenandoahBarrierSet;
69 }
70
71 bool ShenandoahBarrierSet::is_aligned(HeapWord* hw) {
72 return true;
73 }
74
75 bool ShenandoahBarrierSet::need_load_reference_barrier(DecoratorSet decorators, BasicType type) {
76 if (!ShenandoahLoadRefBarrier) return false;
77 // Only needed for references
78 if (!is_reference_type(type)) return false;
79 return true;
80 }
81
82 bool ShenandoahBarrierSet::use_native_load_reference_barrier(DecoratorSet decorators, BasicType type) {
83 assert(need_load_reference_barrier(decorators, type), "Why ask?");
84 assert(is_reference_type(type), "Why we here?");
85 // Native load reference barrier is only needed for concurrent root processing
86 if (!ShenandoahConcurrentRoots::can_do_concurrent_roots()) {
87 return false;
88 }
89
90 return (decorators & IN_NATIVE) != 0;
91 }
92
93 bool ShenandoahBarrierSet::need_keep_alive_barrier(DecoratorSet decorators,BasicType type) {
94 if (!ShenandoahKeepAliveBarrier) return false;
95 // Only needed for references
96 if (!is_reference_type(type)) return false;
97
98 bool keep_alive = (decorators & AS_NO_KEEPALIVE) == 0;
99 bool unknown = (decorators & ON_UNKNOWN_OOP_REF) != 0;
100 bool is_traversal_mode = ShenandoahHeap::heap()->is_traversal_mode();
101 bool on_weak_ref = (decorators & (ON_WEAK_OOP_REF | ON_PHANTOM_OOP_REF)) != 0;
102 return (on_weak_ref || unknown) && (keep_alive || is_traversal_mode);
103 }
104
105 template <class T>
106 inline void ShenandoahBarrierSet::inline_write_ref_field_pre(T* field, oop new_val) {
107 shenandoah_assert_not_in_cset_loc_except(field, _heap->cancelled_gc());
108 if (_heap->is_concurrent_mark_in_progress()) {
109 T heap_oop = RawAccess<>::oop_load(field);
110 if (!CompressedOops::is_null(heap_oop)) {
111 enqueue(CompressedOops::decode(heap_oop));
112 }
113 }
114 }
115
116 // These are the more general virtual versions.
117 void ShenandoahBarrierSet::write_ref_field_pre_work(oop* field, oop new_val) {
118 inline_write_ref_field_pre(field, new_val);
119 }
120
121 void ShenandoahBarrierSet::write_ref_field_pre_work(narrowOop* field, oop new_val) {
122 inline_write_ref_field_pre(field, new_val);
123 }
124
125 void ShenandoahBarrierSet::write_ref_field_pre_work(void* field, oop new_val) {
126 guarantee(false, "Not needed");
127 }
128
129 void ShenandoahBarrierSet::write_ref_field_work(void* v, oop o, bool release) {
130 shenandoah_assert_not_in_cset_loc_except(v, _heap->cancelled_gc());
131 shenandoah_assert_not_forwarded_except (v, o, o == NULL || _heap->cancelled_gc() || !_heap->is_concurrent_mark_in_progress());
132 shenandoah_assert_not_in_cset_except (v, o, o == NULL || _heap->cancelled_gc() || !_heap->is_concurrent_mark_in_progress());
133 }
134
135 oop ShenandoahBarrierSet::load_reference_barrier_not_null(oop obj) {
136 if (ShenandoahLoadRefBarrier && _heap->has_forwarded_objects()) {
137 return load_reference_barrier_impl(obj);
138 } else {
139 return obj;
140 }
141 }
142
143 oop ShenandoahBarrierSet::load_reference_barrier(oop obj) {
144 if (obj != NULL) {
145 return load_reference_barrier_not_null(obj);
146 } else {
147 return obj;
148 }
149 }
150
151 oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, oop* load_addr) {
152 return load_reference_barrier_mutator_work(obj, load_addr);
153 }
154
155 oop ShenandoahBarrierSet::load_reference_barrier_mutator(oop obj, narrowOop* load_addr) {
156 return load_reference_barrier_mutator_work(obj, load_addr);
157 }
158
159 template <class T>
160 oop ShenandoahBarrierSet::load_reference_barrier_mutator_work(oop obj, T* load_addr) {
161 assert(ShenandoahLoadRefBarrier, "should be enabled");
162 shenandoah_assert_in_cset(load_addr, obj);
163
164 oop fwd = resolve_forwarded_not_null(obj);
165 if (obj == fwd) {
166 assert(_heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL),
167 "evac should be in progress");
168
169 ShenandoahEvacOOMScope oom_evac_scope;
170
171 Thread* thread = Thread::current();
172 oop res_oop = _heap->evacuate_object(obj, thread);
173
174 // Since we are already here and paid the price of getting through runtime call adapters
175 // and acquiring oom-scope, it makes sense to try and evacuate more adjacent objects,
176 // thus amortizing the overhead. For sparsely live heaps, scan costs easily dominate
177 // total assist costs, and can introduce a lot of evacuation latency. This is why we
178 // only scan for _nearest_ N objects, regardless if they are eligible for evac or not.
179 // The scan itself should also avoid touching the non-marked objects below TAMS, because
180 // their metadata (notably, klasses) may be incorrect already.
181
182 size_t max = ShenandoahEvacAssist;
183 if (max > 0) {
184 // Traversal is special: it uses incomplete marking context, because it coalesces evac with mark.
185 // Other code uses complete marking context, because evac happens after the mark.
186 ShenandoahMarkingContext* ctx = _heap->is_concurrent_traversal_in_progress() ?
187 _heap->marking_context() : _heap->complete_marking_context();
188
189 ShenandoahHeapRegion* r = _heap->heap_region_containing(obj);
190 assert(r->is_cset(), "sanity");
191
192 HeapWord* cur = (HeapWord*)obj + obj->size();
193
194 size_t count = 0;
195 while ((cur < r->top()) && ctx->is_marked(oop(cur)) && (count++ < max)) {
196 oop cur_oop = oop(cur);
197 if (cur_oop == resolve_forwarded_not_null(cur_oop)) {
198 _heap->evacuate_object(cur_oop, thread);
199 }
200 cur = cur + cur_oop->size();
201 }
202 }
203
204 fwd = res_oop;
205 }
206
207 if (load_addr != NULL && fwd != obj) {
208 // Since we are here and we know the load address, update the reference.
209 ShenandoahHeap::cas_oop(fwd, load_addr, obj);
210 }
211
212 return fwd;
213 }
214
215 oop ShenandoahBarrierSet::load_reference_barrier_impl(oop obj) {
216 assert(ShenandoahLoadRefBarrier, "should be enabled");
217 if (!CompressedOops::is_null(obj)) {
218 bool evac_in_progress = _heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL);
219 oop fwd = resolve_forwarded_not_null(obj);
220 if (evac_in_progress &&
221 _heap->in_collection_set(obj) &&
222 obj == fwd) {
223 Thread *t = Thread::current();
224 if (t->is_GC_task_thread()) {
225 return _heap->evacuate_object(obj, t);
226 } else {
227 ShenandoahEvacOOMScope oom_evac_scope;
228 return _heap->evacuate_object(obj, t);
229 }
230 } else {
231 return fwd;
232 }
233 } else {
234 return obj;
235 }
236 }
237
238 void ShenandoahBarrierSet::storeval_barrier(oop obj) {
239 if (ShenandoahStoreValEnqueueBarrier && !CompressedOops::is_null(obj) && _heap->is_concurrent_traversal_in_progress()) {
240 enqueue(obj);
241 }
242 }
243
244 void ShenandoahBarrierSet::keep_alive_barrier(oop obj) {
245 if (ShenandoahKeepAliveBarrier && _heap->is_concurrent_mark_in_progress()) {
246 enqueue(obj);
247 }
248 }
249
250 void ShenandoahBarrierSet::enqueue(oop obj) {
251 shenandoah_assert_not_forwarded_if(NULL, obj, _heap->is_concurrent_traversal_in_progress());
252 assert(_satb_mark_queue_set.is_active(), "only get here when SATB active");
253
254 // Filter marked objects before hitting the SATB queues. The same predicate would
255 // be used by SATBMQ::filter to eliminate already marked objects downstream, but
256 // filtering here helps to avoid wasteful SATB queueing work to begin with.
257 if (!_heap->requires_marking<false>(obj)) return;
258
259 ShenandoahThreadLocalData::satb_mark_queue(Thread::current()).enqueue_known_active(obj);
260 }
261
262 void ShenandoahBarrierSet::on_thread_create(Thread* thread) {
263 // Create thread local data
264 ShenandoahThreadLocalData::create(thread);
265 }
266
267 void ShenandoahBarrierSet::on_thread_destroy(Thread* thread) {
268 // Destroy thread local data
269 ShenandoahThreadLocalData::destroy(thread);
270 }
271
272 void ShenandoahBarrierSet::on_thread_attach(Thread *thread) {
273 assert(!thread->is_Java_thread() || !SafepointSynchronize::is_at_safepoint(),
274 "We should not be at a safepoint");
275 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
276 assert(!queue.is_active(), "SATB queue should not be active");
277 assert( queue.is_empty(), "SATB queue should be empty");
278 queue.set_active(_satb_mark_queue_set.is_active());
279 if (thread->is_Java_thread()) {
280 ShenandoahThreadLocalData::set_gc_state(thread, _heap->gc_state());
281 ShenandoahThreadLocalData::initialize_gclab(thread);
282 }
283 }
284
285 void ShenandoahBarrierSet::on_thread_detach(Thread *thread) {
286 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
287 queue.flush();
288 if (thread->is_Java_thread()) {
289 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
290 if (gclab != NULL) {
291 gclab->retire();
292 }
293 }
294 }
295
296 oop ShenandoahBarrierSet::load_reference_barrier_native(oop obj, oop* load_addr) {
297 return load_reference_barrier_native_impl(obj, load_addr);
298 }
299
300 oop ShenandoahBarrierSet::load_reference_barrier_native(oop obj, narrowOop* load_addr) {
301 // Assumption: narrow oop version should not be used anywhere.
302 ShouldNotReachHere();
303 return NULL;
304 }
305
306 template <class T>
307 oop ShenandoahBarrierSet::load_reference_barrier_native_impl(oop obj, T* load_addr) {
308 if (CompressedOops::is_null(obj)) {
309 return NULL;
310 }
311
312 ShenandoahMarkingContext* const marking_context = _heap->marking_context();
313 if (_heap->is_evacuation_in_progress() && !marking_context->is_marked(obj)) {
314 Thread* thr = Thread::current();
315 if (thr->is_Java_thread()) {
316 return NULL;
317 } else {
318 return obj;
319 }
320 }
321
322 oop fwd = load_reference_barrier_not_null(obj);
323 if (load_addr != NULL && fwd != obj) {
324 // Since we are here and we know the load address, update the reference.
325 ShenandoahHeap::cas_oop(fwd, load_addr, obj);
326 }
327
328 return fwd;
329 }
330
331 void ShenandoahBarrierSet::clone_barrier_runtime(oop src) {
332 if (_heap->has_forwarded_objects()) {
333 clone_barrier(src);
334 }
335 }
336