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