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/g1/g1BarrierSet.hpp"
26 #include "gc/shenandoah/shenandoahAsserts.hpp"
27 #include "gc/shenandoah/shenandoahBarrierSet.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 template <bool STOREVAL_WRITE_BARRIER>
46 class ShenandoahUpdateRefsForOopClosure: public BasicOopIterateClosure {
47 private:
48 ShenandoahHeap* _heap;
49 ShenandoahBarrierSet* _bs;
50
51 template <class T>
52 inline void do_oop_work(T* p) {
53 oop o;
54 if (STOREVAL_WRITE_BARRIER) {
55 o = _heap->evac_update_with_forwarded(p);
56 if (!CompressedOops::is_null(o)) {
57 _bs->enqueue(o);
58 }
59 } else {
60 _heap->maybe_update_with_forwarded(p);
61 }
62 }
63 public:
64 ShenandoahUpdateRefsForOopClosure() : _heap(ShenandoahHeap::heap()), _bs(ShenandoahBarrierSet::barrier_set()) {
65 assert(UseShenandoahGC && ShenandoahCloneBarrier, "should be enabled");
66 }
67
68 virtual void do_oop(oop* p) { do_oop_work(p); }
69 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
70 };
71
72 ShenandoahBarrierSet::ShenandoahBarrierSet(ShenandoahHeap* heap) :
73 BarrierSet(make_barrier_set_assembler<ShenandoahBarrierSetAssembler>(),
74 make_barrier_set_c1<ShenandoahBarrierSetC1>(),
75 make_barrier_set_c2<ShenandoahBarrierSetC2>(),
76 NULL /* barrier_set_nmethod */,
77 BarrierSet::FakeRtti(BarrierSet::ShenandoahBarrierSet)),
78 _heap(heap),
79 _satb_mark_queue_set()
80 {
81 }
82
83 ShenandoahBarrierSetAssembler* ShenandoahBarrierSet::assembler() {
84 BarrierSetAssembler* const bsa = BarrierSet::barrier_set()->barrier_set_assembler();
85 return reinterpret_cast<ShenandoahBarrierSetAssembler*>(bsa);
86 }
87
88 void ShenandoahBarrierSet::print_on(outputStream* st) const {
89 st->print("ShenandoahBarrierSet");
90 }
91
92 bool ShenandoahBarrierSet::is_a(BarrierSet::Name bsn) {
93 return bsn == BarrierSet::ShenandoahBarrierSet;
94 }
95
96 bool ShenandoahBarrierSet::is_aligned(HeapWord* hw) {
97 return true;
98 }
99
100 template <class T, bool STOREVAL_WRITE_BARRIER>
101 void ShenandoahBarrierSet::write_ref_array_loop(HeapWord* start, size_t count) {
102 assert(UseShenandoahGC && ShenandoahCloneBarrier, "should be enabled");
103 ShenandoahUpdateRefsForOopClosure<STOREVAL_WRITE_BARRIER> cl;
104 T* dst = (T*) start;
105 for (size_t i = 0; i < count; i++) {
106 cl.do_oop(dst++);
107 }
108 }
109
110 void ShenandoahBarrierSet::write_ref_array(HeapWord* start, size_t count) {
111 assert(UseShenandoahGC, "should be enabled");
112 if (count == 0) return;
113 if (!ShenandoahCloneBarrier) return;
114
115 if (!need_update_refs_barrier()) return;
116
117 if (_heap->is_concurrent_traversal_in_progress()) {
118 ShenandoahEvacOOMScope oom_evac_scope;
119 if (UseCompressedOops) {
120 write_ref_array_loop<narrowOop, /* wb = */ true>(start, count);
121 } else {
122 write_ref_array_loop<oop, /* wb = */ true>(start, count);
123 }
124 } else {
125 if (UseCompressedOops) {
126 write_ref_array_loop<narrowOop, /* wb = */ false>(start, count);
127 } else {
128 write_ref_array_loop<oop, /* wb = */ false>(start, count);
129 }
130 }
131 }
132
133 template <class T>
134 void ShenandoahBarrierSet::write_ref_array_pre_work(T* dst, size_t count) {
135 shenandoah_assert_not_in_cset_loc_except(dst, _heap->cancelled_gc());
136 if (ShenandoahSATBBarrier && _heap->is_concurrent_mark_in_progress()) {
137 T* elem_ptr = dst;
138 for (size_t i = 0; i < count; i++, elem_ptr++) {
139 T heap_oop = RawAccess<>::oop_load(elem_ptr);
140 if (!CompressedOops::is_null(heap_oop)) {
141 enqueue(CompressedOops::decode_not_null(heap_oop));
142 }
143 }
144 }
145 }
146
147 void ShenandoahBarrierSet::write_ref_array_pre(oop* dst, size_t count, bool dest_uninitialized) {
148 if (! dest_uninitialized) {
149 write_ref_array_pre_work(dst, count);
150 }
151 }
152
153 void ShenandoahBarrierSet::write_ref_array_pre(narrowOop* dst, size_t count, bool dest_uninitialized) {
154 if (! dest_uninitialized) {
155 write_ref_array_pre_work(dst, count);
156 }
157 }
158
159 template <class T>
160 inline void ShenandoahBarrierSet::inline_write_ref_field_pre(T* field, oop new_val) {
161 shenandoah_assert_not_in_cset_loc_except(field, _heap->cancelled_gc());
162 if (_heap->is_concurrent_mark_in_progress()) {
163 T heap_oop = RawAccess<>::oop_load(field);
164 if (!CompressedOops::is_null(heap_oop)) {
165 enqueue(CompressedOops::decode(heap_oop));
166 }
167 }
168 }
169
170 // These are the more general virtual versions.
171 void ShenandoahBarrierSet::write_ref_field_pre_work(oop* field, oop new_val) {
172 inline_write_ref_field_pre(field, new_val);
173 }
174
175 void ShenandoahBarrierSet::write_ref_field_pre_work(narrowOop* field, oop new_val) {
176 inline_write_ref_field_pre(field, new_val);
177 }
178
179 void ShenandoahBarrierSet::write_ref_field_pre_work(void* field, oop new_val) {
180 guarantee(false, "Not needed");
181 }
182
183 void ShenandoahBarrierSet::write_ref_field_work(void* v, oop o, bool release) {
184 shenandoah_assert_not_in_cset_loc_except(v, _heap->cancelled_gc());
185 shenandoah_assert_not_forwarded_except (v, o, o == NULL || _heap->cancelled_gc() || !_heap->is_concurrent_mark_in_progress());
186 shenandoah_assert_not_in_cset_except (v, o, o == NULL || _heap->cancelled_gc() || !_heap->is_concurrent_mark_in_progress());
187 }
188
189 void ShenandoahBarrierSet::write_region(MemRegion mr) {
190 assert(UseShenandoahGC, "should be enabled");
191 if (!ShenandoahCloneBarrier) return;
192 if (! need_update_refs_barrier()) return;
193
194 // This is called for cloning an object (see jvm.cpp) after the clone
195 // has been made. We are not interested in any 'previous value' because
196 // it would be NULL in any case. But we *are* interested in any oop*
197 // that potentially need to be updated.
198
199 oop obj = oop(mr.start());
200 shenandoah_assert_correct(NULL, obj);
201 if (_heap->is_concurrent_traversal_in_progress()) {
202 ShenandoahEvacOOMScope oom_evac_scope;
203 ShenandoahUpdateRefsForOopClosure</* wb = */ true> cl;
204 obj->oop_iterate(&cl);
205 } else {
206 ShenandoahUpdateRefsForOopClosure</* wb = */ false> cl;
207 obj->oop_iterate(&cl);
208 }
209 }
210
211 oop ShenandoahBarrierSet::read_barrier(oop src) {
212 // Check for forwarded objects, because on Full GC path we might deal with
213 // non-trivial fwdptrs that contain Full GC specific metadata. We could check
214 // for is_full_gc_in_progress(), but this also covers the case of stable heap,
215 // which provides a bit of performance improvement.
216 if (ShenandoahReadBarrier && _heap->has_forwarded_objects()) {
217 return ShenandoahBarrierSet::resolve_forwarded(src);
218 } else {
219 return src;
220 }
221 }
222
223 bool ShenandoahBarrierSet::obj_equals(oop obj1, oop obj2) {
224 bool eq = oopDesc::equals_raw(obj1, obj2);
225 if (! eq && ShenandoahAcmpBarrier) {
226 OrderAccess::loadload();
227 obj1 = resolve_forwarded(obj1);
228 obj2 = resolve_forwarded(obj2);
229 eq = oopDesc::equals_raw(obj1, obj2);
230 }
231 return eq;
232 }
233
234 oop ShenandoahBarrierSet::write_barrier_mutator(oop obj) {
235 assert(UseShenandoahGC && ShenandoahWriteBarrier, "should be enabled");
236 assert(_heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL), "evac should be in progress");
237 shenandoah_assert_in_cset(NULL, obj);
238
239 oop fwd = resolve_forwarded_not_null(obj);
240 if (oopDesc::equals_raw(obj, fwd)) {
241 ShenandoahEvacOOMScope oom_evac_scope;
242
243 Thread* thread = Thread::current();
244 oop res_oop = _heap->evacuate_object(obj, thread);
245
246 // Since we are already here and paid the price of getting through runtime call adapters
247 // and acquiring oom-scope, it makes sense to try and evacuate more adjacent objects,
248 // thus amortizing the overhead. For sparsely live heaps, scan costs easily dominate
249 // total assist costs, and can introduce a lot of evacuation latency. This is why we
250 // only scan for _nearest_ N objects, regardless if they are eligible for evac or not.
251 // The scan itself should also avoid touching the non-marked objects below TAMS, because
252 // their metadata (notably, klasses) may be incorrect already.
253
254 size_t max = ShenandoahEvacAssist;
255 if (max > 0) {
256 // Traversal is special: it uses incomplete marking context, because it coalesces evac with mark.
257 // Other code uses complete marking context, because evac happens after the mark.
258 ShenandoahMarkingContext* ctx = _heap->is_concurrent_traversal_in_progress() ?
259 _heap->marking_context() : _heap->complete_marking_context();
260
261 ShenandoahHeapRegion* r = _heap->heap_region_containing(obj);
262 assert(r->is_cset(), "sanity");
263
264 HeapWord* cur = (HeapWord*)obj + obj->size() + ShenandoahBrooksPointer::word_size();
265
266 size_t count = 0;
267 while ((cur < r->top()) && ctx->is_marked(oop(cur)) && (count++ < max)) {
268 oop cur_oop = oop(cur);
269 if (oopDesc::equals_raw(cur_oop, resolve_forwarded_not_null(cur_oop))) {
270 _heap->evacuate_object(cur_oop, thread);
271 }
272 cur = cur + cur_oop->size() + ShenandoahBrooksPointer::word_size();
273 }
274 }
275
276 return res_oop;
277 }
278 return fwd;
279 }
280
281 oop ShenandoahBarrierSet::write_barrier_impl(oop obj) {
282 assert(UseShenandoahGC && ShenandoahWriteBarrier, "should be enabled");
283 if (!CompressedOops::is_null(obj)) {
284 bool evac_in_progress = _heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL);
285 oop fwd = resolve_forwarded_not_null(obj);
286 if (evac_in_progress &&
287 _heap->in_collection_set(obj) &&
288 oopDesc::equals_raw(obj, fwd)) {
289 Thread *t = Thread::current();
290 if (t->is_GC_task_thread()) {
291 return _heap->evacuate_object(obj, t);
292 } else {
293 ShenandoahEvacOOMScope oom_evac_scope;
294 return _heap->evacuate_object(obj, t);
295 }
296 } else {
297 return fwd;
298 }
299 } else {
300 return obj;
301 }
302 }
303
304 oop ShenandoahBarrierSet::write_barrier(oop obj) {
305 if (ShenandoahWriteBarrier && _heap->has_forwarded_objects()) {
306 return write_barrier_impl(obj);
307 } else {
308 return obj;
309 }
310 }
311
312 oop ShenandoahBarrierSet::storeval_barrier(oop obj) {
313 if (ShenandoahStoreValEnqueueBarrier) {
314 if (!CompressedOops::is_null(obj)) {
315 obj = write_barrier(obj);
316 enqueue(obj);
317 }
318 }
319 if (ShenandoahStoreValReadBarrier) {
320 obj = resolve_forwarded(obj);
321 }
322 return obj;
323 }
324
325 void ShenandoahBarrierSet::keep_alive_barrier(oop obj) {
326 if (ShenandoahKeepAliveBarrier && _heap->is_concurrent_mark_in_progress()) {
327 enqueue(obj);
328 }
329 }
330
331 void ShenandoahBarrierSet::enqueue(oop obj) {
332 shenandoah_assert_not_forwarded_if(NULL, obj, _heap->is_concurrent_traversal_in_progress());
333 if (!_satb_mark_queue_set.is_active()) return;
334
335 // Filter marked objects before hitting the SATB queues. The same predicate would
336 // be used by SATBMQ::filter to eliminate already marked objects downstream, but
337 // filtering here helps to avoid wasteful SATB queueing work to begin with.
338 if (!_heap->requires_marking(obj)) return;
339
340 Thread* thr = Thread::current();
341 if (thr->is_Java_thread()) {
342 ShenandoahThreadLocalData::satb_mark_queue(thr).enqueue(obj);
343 } else {
344 MutexLockerEx x(Shared_SATB_Q_lock, Mutex::_no_safepoint_check_flag);
345 _satb_mark_queue_set.shared_satb_queue()->enqueue(obj);
346 }
347 }
348
349 void ShenandoahBarrierSet::on_thread_create(Thread* thread) {
350 // Create thread local data
351 ShenandoahThreadLocalData::create(thread);
352 }
353
354 void ShenandoahBarrierSet::on_thread_destroy(Thread* thread) {
355 // Destroy thread local data
356 ShenandoahThreadLocalData::destroy(thread);
357 }
358
359 void ShenandoahBarrierSet::on_thread_attach(JavaThread* thread) {
360 assert(!SafepointSynchronize::is_at_safepoint(), "We should not be at a safepoint");
361 assert(!ShenandoahThreadLocalData::satb_mark_queue(thread).is_active(), "SATB queue should not be active");
362 assert(ShenandoahThreadLocalData::satb_mark_queue(thread).is_empty(), "SATB queue should be empty");
363 if (ShenandoahBarrierSet::satb_mark_queue_set().is_active()) {
364 ShenandoahThreadLocalData::satb_mark_queue(thread).set_active(true);
365 }
366 ShenandoahThreadLocalData::set_gc_state(thread, _heap->gc_state());
367 ShenandoahThreadLocalData::initialize_gclab(thread);
368 }
369
370 void ShenandoahBarrierSet::on_thread_detach(JavaThread* thread) {
371 ShenandoahThreadLocalData::satb_mark_queue(thread).flush();
372 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
373 if (gclab != NULL) {
374 gclab->retire();
375 }
376 }