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 if (ShenandoahSATBBarrier && _heap->is_concurrent_mark_in_progress()) {
136 T* elem_ptr = dst;
137 for (size_t i = 0; i < count; i++, elem_ptr++) {
138 T heap_oop = RawAccess<>::oop_load(elem_ptr);
139 if (!CompressedOops::is_null(heap_oop)) {
140 enqueue(CompressedOops::decode_not_null(heap_oop));
141 }
142 }
143 }
144 }
145
146 void ShenandoahBarrierSet::write_ref_array_pre(oop* dst, size_t count, bool dest_uninitialized) {
147 if (! dest_uninitialized) {
148 write_ref_array_pre_work(dst, count);
149 }
150 }
151
152 void ShenandoahBarrierSet::write_ref_array_pre(narrowOop* dst, size_t count, bool dest_uninitialized) {
153 if (! dest_uninitialized) {
154 write_ref_array_pre_work(dst, count);
155 }
156 }
157
158 template <class T>
159 inline void ShenandoahBarrierSet::inline_write_ref_field_pre(T* field, oop new_val) {
160 shenandoah_assert_not_in_cset_loc_except(field, _heap->cancelled_gc());
161 if (_heap->is_concurrent_mark_in_progress()) {
162 T heap_oop = RawAccess<>::oop_load(field);
163 if (!CompressedOops::is_null(heap_oop)) {
164 enqueue(CompressedOops::decode(heap_oop));
165 }
166 }
167 }
168
169 // These are the more general virtual versions.
170 void ShenandoahBarrierSet::write_ref_field_pre_work(oop* field, oop new_val) {
171 inline_write_ref_field_pre(field, new_val);
172 }
173
174 void ShenandoahBarrierSet::write_ref_field_pre_work(narrowOop* field, oop new_val) {
175 inline_write_ref_field_pre(field, new_val);
176 }
177
178 void ShenandoahBarrierSet::write_ref_field_pre_work(void* field, oop new_val) {
179 guarantee(false, "Not needed");
180 }
181
182 void ShenandoahBarrierSet::write_ref_field_work(void* v, oop o, bool release) {
183 shenandoah_assert_not_in_cset_loc_except(v, _heap->cancelled_gc());
184 shenandoah_assert_not_forwarded_except (v, o, o == NULL || _heap->cancelled_gc() || !_heap->is_concurrent_mark_in_progress());
185 shenandoah_assert_not_in_cset_except (v, o, o == NULL || _heap->cancelled_gc() || !_heap->is_concurrent_mark_in_progress());
186 }
187
188 void ShenandoahBarrierSet::write_region(MemRegion mr) {
189 assert(UseShenandoahGC, "should be enabled");
190 if (!ShenandoahCloneBarrier) return;
191 if (! need_update_refs_barrier()) return;
192
193 // This is called for cloning an object (see jvm.cpp) after the clone
194 // has been made. We are not interested in any 'previous value' because
195 // it would be NULL in any case. But we *are* interested in any oop*
196 // that potentially need to be updated.
197
198 oop obj = oop(mr.start());
199 shenandoah_assert_correct(NULL, obj);
200 if (_heap->is_concurrent_traversal_in_progress()) {
201 ShenandoahEvacOOMScope oom_evac_scope;
202 ShenandoahUpdateRefsForOopClosure</* wb = */ true> cl;
203 obj->oop_iterate(&cl);
204 } else {
205 ShenandoahUpdateRefsForOopClosure</* wb = */ false> cl;
206 obj->oop_iterate(&cl);
207 }
208 }
209
210 oop ShenandoahBarrierSet::read_barrier(oop src) {
211 // Check for forwarded objects, because on Full GC path we might deal with
212 // non-trivial fwdptrs that contain Full GC specific metadata. We could check
213 // for is_full_gc_in_progress(), but this also covers the case of stable heap,
214 // which provides a bit of performance improvement.
215 if (ShenandoahReadBarrier && _heap->has_forwarded_objects()) {
216 return ShenandoahBarrierSet::resolve_forwarded(src);
217 } else {
218 return src;
219 }
220 }
221
222 bool ShenandoahBarrierSet::obj_equals(oop obj1, oop obj2) {
223 bool eq = oopDesc::equals_raw(obj1, obj2);
224 if (! eq && ShenandoahAcmpBarrier) {
225 OrderAccess::loadload();
226 obj1 = resolve_forwarded(obj1);
227 obj2 = resolve_forwarded(obj2);
228 eq = oopDesc::equals_raw(obj1, obj2);
229 }
230 return eq;
231 }
232
233 oop ShenandoahBarrierSet::write_barrier_mutator(oop obj) {
234 assert(UseShenandoahGC && ShenandoahWriteBarrier, "should be enabled");
235 assert(_heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL), "evac should be in progress");
236 shenandoah_assert_in_cset(NULL, obj);
237
238 oop fwd = resolve_forwarded_not_null(obj);
239 if (oopDesc::equals_raw(obj, fwd)) {
240 ShenandoahEvacOOMScope oom_evac_scope;
241
242 Thread* thread = Thread::current();
243 oop res_oop = _heap->evacuate_object(obj, thread);
244
245 // Since we are already here and paid the price of getting through runtime call adapters
246 // and acquiring oom-scope, it makes sense to try and evacuate more adjacent objects,
247 // thus amortizing the overhead. For sparsely live heaps, scan costs easily dominate
248 // total assist costs, and can introduce a lot of evacuation latency. This is why we
249 // only scan for _nearest_ N objects, regardless if they are eligible for evac or not.
250 // The scan itself should also avoid touching the non-marked objects below TAMS, because
251 // their metadata (notably, klasses) may be incorrect already.
252
253 size_t max = ShenandoahEvacAssist;
254 if (max > 0) {
255 // Traversal is special: it uses incomplete marking context, because it coalesces evac with mark.
256 // Other code uses complete marking context, because evac happens after the mark.
257 ShenandoahMarkingContext* ctx = _heap->is_concurrent_traversal_in_progress() ?
258 _heap->marking_context() : _heap->complete_marking_context();
259
260 ShenandoahHeapRegion* r = _heap->heap_region_containing(obj);
261 assert(r->is_cset(), "sanity");
262
263 HeapWord* cur = (HeapWord*)obj + obj->size() + ShenandoahBrooksPointer::word_size();
264
265 size_t count = 0;
266 while ((cur < r->top()) && ctx->is_marked(oop(cur)) && (count++ < max)) {
267 oop cur_oop = oop(cur);
268 if (oopDesc::equals_raw(cur_oop, resolve_forwarded_not_null(cur_oop))) {
269 _heap->evacuate_object(cur_oop, thread);
270 }
271 cur = cur + cur_oop->size() + ShenandoahBrooksPointer::word_size();
272 }
273 }
274
275 return res_oop;
276 }
277 return fwd;
278 }
279
280 oop ShenandoahBarrierSet::write_barrier_impl(oop obj) {
281 assert(UseShenandoahGC && ShenandoahWriteBarrier, "should be enabled");
282 if (!CompressedOops::is_null(obj)) {
283 bool evac_in_progress = _heap->is_gc_in_progress_mask(ShenandoahHeap::EVACUATION | ShenandoahHeap::TRAVERSAL);
284 oop fwd = resolve_forwarded_not_null(obj);
285 if (evac_in_progress &&
286 _heap->in_collection_set(obj) &&
287 oopDesc::equals_raw(obj, fwd)) {
288 Thread *t = Thread::current();
289 if (t->is_GC_task_thread()) {
290 return _heap->evacuate_object(obj, t);
291 } else {
292 ShenandoahEvacOOMScope oom_evac_scope;
293 return _heap->evacuate_object(obj, t);
294 }
295 } else {
296 return fwd;
297 }
298 } else {
299 return obj;
300 }
301 }
302
303 oop ShenandoahBarrierSet::write_barrier(oop obj) {
304 if (ShenandoahWriteBarrier && _heap->has_forwarded_objects()) {
305 return write_barrier_impl(obj);
306 } else {
307 return obj;
308 }
309 }
310
311 oop ShenandoahBarrierSet::storeval_barrier(oop obj) {
312 if (ShenandoahStoreValEnqueueBarrier) {
313 if (!CompressedOops::is_null(obj)) {
314 obj = write_barrier(obj);
315 enqueue(obj);
316 }
317 }
318 if (ShenandoahStoreValReadBarrier) {
319 obj = resolve_forwarded(obj);
320 }
321 return obj;
322 }
323
324 void ShenandoahBarrierSet::keep_alive_barrier(oop obj) {
325 if (ShenandoahKeepAliveBarrier && _heap->is_concurrent_mark_in_progress()) {
326 enqueue(obj);
327 }
328 }
329
330 void ShenandoahBarrierSet::enqueue(oop obj) {
331 shenandoah_assert_not_forwarded_if(NULL, obj, _heap->is_concurrent_traversal_in_progress());
332 if (!_satb_mark_queue_set.is_active()) return;
333
334 // Filter marked objects before hitting the SATB queues. The same predicate would
335 // be used by SATBMQ::filter to eliminate already marked objects downstream, but
336 // filtering here helps to avoid wasteful SATB queueing work to begin with.
337 if (!_heap->requires_marking<false>(obj)) return;
338
339 ShenandoahThreadLocalData::satb_mark_queue(Thread::current()).enqueue(obj);
340 }
341
342 void ShenandoahBarrierSet::on_thread_create(Thread* thread) {
343 // Create thread local data
344 ShenandoahThreadLocalData::create(thread);
345 }
346
347 void ShenandoahBarrierSet::on_thread_destroy(Thread* thread) {
348 // Destroy thread local data
349 ShenandoahThreadLocalData::destroy(thread);
350 }
351
352 void ShenandoahBarrierSet::on_thread_attach(Thread *thread) {
353 assert(!thread->is_Java_thread() || !SafepointSynchronize::is_at_safepoint(),
354 "We should not be at a safepoint");
355 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
356 assert(!queue.is_active(), "SATB queue should not be active");
357 assert( queue.is_empty(), "SATB queue should be empty");
358 queue.set_active(_satb_mark_queue_set.is_active());
359 if (thread->is_Java_thread()) {
360 ShenandoahThreadLocalData::set_gc_state(thread, _heap->gc_state());
361 ShenandoahThreadLocalData::initialize_gclab(thread);
362 }
363 }
364
365 void ShenandoahBarrierSet::on_thread_detach(Thread *thread) {
366 SATBMarkQueue& queue = ShenandoahThreadLocalData::satb_mark_queue(thread);
367 queue.flush();
368 if (thread->is_Java_thread()) {
369 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread);
370 if (gclab != NULL) {
371 gclab->retire();
372 }
373 }
374 }