46
47 inline PSPromotionManager* PSPromotionManager::manager_array(uint index) {
48 assert(_manager_array != nullptr, "access of null manager_array");
49 assert(index < ParallelGCThreads, "out of range manager_array access");
50 return &_manager_array[index];
51 }
52
53 inline void PSPromotionManager::push_depth(ScannerTask task) {
54 claimed_stack_depth()->push(task);
55 }
56
57 template <class T>
58 inline void PSPromotionManager::claim_or_forward_depth(T* p) {
59 assert(should_scavenge(p, true), "revisiting object?");
60 assert(ParallelScavengeHeap::heap()->is_in(p), "pointer outside heap");
61 oop obj = RawAccess<IS_NOT_NULL>::oop_load(p);
62 Prefetch::write(obj->mark_addr(), 0);
63 push_depth(ScannerTask(p));
64 }
65
66 inline void PSPromotionManager::promotion_trace_event(oop new_obj, oop old_obj,
67 size_t obj_size,
68 uint age, bool tenured,
69 const PSPromotionLAB* lab) {
70 // Skip if memory allocation failed
71 if (new_obj != nullptr) {
72 const ParallelScavengeTracer* gc_tracer = PSScavenge::gc_tracer();
73
74 if (lab != nullptr) {
75 // Promotion of object through newly allocated PLAB
76 if (gc_tracer->should_report_promotion_in_new_plab_event()) {
77 size_t obj_bytes = obj_size * HeapWordSize;
78 size_t lab_size = lab->capacity();
79 gc_tracer->report_promotion_in_new_plab_event(old_obj->klass(), obj_bytes,
80 age, tenured, lab_size);
81 }
82 } else {
83 // Promotion of object directly to heap
84 if (gc_tracer->should_report_promotion_outside_plab_event()) {
85 size_t obj_bytes = obj_size * HeapWordSize;
86 gc_tracer->report_promotion_outside_plab_event(old_obj->klass(), obj_bytes,
87 age, tenured);
88 }
89 }
90 }
91 }
92
93 class PSPushContentsClosure: public BasicOopIterateClosure {
94 PSPromotionManager* _pm;
95 public:
96 PSPushContentsClosure(PSPromotionManager* pm) : BasicOopIterateClosure(PSScavenge::reference_processor()), _pm(pm) {}
97
98 template <typename T> void do_oop_nv(T* p) {
99 if (PSScavenge::should_scavenge(p)) {
100 _pm->claim_or_forward_depth(p);
101 }
102 }
103
104 virtual void do_oop(oop* p) { do_oop_nv(p); }
105 virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
106 };
130 obj->oop_iterate_backwards(&pcc);
131 }
132 }
133
134 template<bool promote_immediately>
135 inline oop PSPromotionManager::copy_to_survivor_space(oop o) {
136 assert(should_scavenge(&o), "Sanity");
137
138 // NOTE! We must be very careful with any methods that access the mark
139 // in o. There may be multiple threads racing on it, and it may be forwarded
140 // at any time.
141 markWord m = o->mark();
142 if (!m.is_marked()) {
143 return copy_unmarked_to_survivor_space<promote_immediately>(o, m);
144 } else {
145 // Ensure any loads from the forwardee follow all changes that precede
146 // the release-cmpxchg that performed the forwarding, possibly in some
147 // other thread.
148 OrderAccess::acquire();
149 // Return the already installed forwardee.
150 return cast_to_oop(m.decode_pointer());
151 }
152 }
153
154 //
155 // This method is pretty bulky. It would be nice to split it up
156 // into smaller submethods, but we need to be careful not to hurt
157 // performance.
158 //
159 template<bool promote_immediately>
160 inline oop PSPromotionManager::copy_unmarked_to_survivor_space(oop o,
161 markWord test_mark) {
162 assert(should_scavenge(&o), "Sanity");
163
164 oop new_obj = nullptr;
165 bool new_obj_is_tenured = false;
166 size_t new_obj_size = o->size();
167
168 // Find the objects age, MT safe.
169 uint age = (test_mark.has_displaced_mark_helper() /* o->has_displaced_mark() */) ?
170 test_mark.displaced_mark_helper().age() : test_mark.age();
171
172 if (!promote_immediately) {
173 // Try allocating obj in to-space (unless too old)
174 if (age < PSScavenge::tenuring_threshold()) {
175 new_obj = cast_to_oop(_young_lab.allocate(new_obj_size));
176 if (new_obj == nullptr && !_young_gen_is_full) {
177 // Do we allocate directly, or flush and refill?
178 if (new_obj_size > (YoungPLABSize / 2)) {
179 // Allocate this object directly
180 new_obj = cast_to_oop(young_space()->cas_allocate(new_obj_size));
181 promotion_trace_event(new_obj, o, new_obj_size, age, false, nullptr);
182 } else {
183 // Flush and fill
184 _young_lab.flush();
185
186 HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize);
187 if (lab_base != nullptr) {
188 _young_lab.initialize(MemRegion(lab_base, YoungPLABSize));
189 // Try the young lab allocation again.
190 new_obj = cast_to_oop(_young_lab.allocate(new_obj_size));
191 promotion_trace_event(new_obj, o, new_obj_size, age, false, &_young_lab);
192 } else {
193 _young_gen_is_full = true;
194 }
195 }
196 }
197 }
198 }
199
200 // Otherwise try allocating obj tenured
201 if (new_obj == nullptr) {
202 #ifndef PRODUCT
203 if (ParallelScavengeHeap::heap()->promotion_should_fail()) {
204 return oop_promotion_failed(o, test_mark);
205 }
206 #endif // #ifndef PRODUCT
207
208 new_obj = cast_to_oop(_old_lab.allocate(new_obj_size));
209 new_obj_is_tenured = true;
210
211 if (new_obj == nullptr) {
212 if (!_old_gen_is_full) {
213 // Do we allocate directly, or flush and refill?
214 if (new_obj_size > (OldPLABSize / 2)) {
215 // Allocate this object directly
216 new_obj = cast_to_oop(old_gen()->allocate(new_obj_size));
217 promotion_trace_event(new_obj, o, new_obj_size, age, true, nullptr);
218 } else {
219 // Flush and fill
220 _old_lab.flush();
221
222 HeapWord* lab_base = old_gen()->allocate(OldPLABSize);
223 if(lab_base != nullptr) {
224 _old_lab.initialize(MemRegion(lab_base, OldPLABSize));
225 // Try the old lab allocation again.
226 new_obj = cast_to_oop(_old_lab.allocate(new_obj_size));
227 promotion_trace_event(new_obj, o, new_obj_size, age, true, &_old_lab);
228 }
229 }
230 }
231
232 // This is the promotion failed test, and code handling.
233 // The code belongs here for two reasons. It is slightly
234 // different than the code below, and cannot share the
235 // CAS testing code. Keeping the code here also minimizes
236 // the impact on the common case fast path code.
237
238 if (new_obj == nullptr) {
239 _old_gen_is_full = true;
240 return oop_promotion_failed(o, test_mark);
241 }
242 }
243 }
244
245 assert(new_obj != nullptr, "allocation should have succeeded");
246
247 // Copy obj
248 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(o), cast_from_oop<HeapWord*>(new_obj), new_obj_size);
249
250 // Parallel GC claims with a release - so other threads might access this object
251 // after claiming and they should see the "completed" object.
252 ContinuationGCSupport::transform_stack_chunk(new_obj);
253
254 // Now we have to CAS in the header.
255 // Make copy visible to threads reading the forwardee.
256 oop forwardee = o->forward_to_atomic(new_obj, test_mark, memory_order_release);
257 if (forwardee == nullptr) { // forwardee is null when forwarding is successful
258 // We won any races, we "own" this object.
259 assert(new_obj == o->forwardee(), "Sanity");
260
261 // Increment age if obj still in new generation. Now that
262 // we're dealing with a markWord that cannot change, it is
263 // okay to use the non mt safe oop methods.
264 if (!new_obj_is_tenured) {
265 new_obj->incr_age();
266 assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");
267 }
268
269 // Do the size comparison first with new_obj_size, which we
270 // already have. Hopefully, only a few objects are larger than
271 // _min_array_size_for_chunking, and most of them will be arrays.
272 // So, the is->objArray() test would be very infrequent.
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46
47 inline PSPromotionManager* PSPromotionManager::manager_array(uint index) {
48 assert(_manager_array != nullptr, "access of null manager_array");
49 assert(index < ParallelGCThreads, "out of range manager_array access");
50 return &_manager_array[index];
51 }
52
53 inline void PSPromotionManager::push_depth(ScannerTask task) {
54 claimed_stack_depth()->push(task);
55 }
56
57 template <class T>
58 inline void PSPromotionManager::claim_or_forward_depth(T* p) {
59 assert(should_scavenge(p, true), "revisiting object?");
60 assert(ParallelScavengeHeap::heap()->is_in(p), "pointer outside heap");
61 oop obj = RawAccess<IS_NOT_NULL>::oop_load(p);
62 Prefetch::write(obj->mark_addr(), 0);
63 push_depth(ScannerTask(p));
64 }
65
66 inline void PSPromotionManager::promotion_trace_event(oop new_obj, Klass* klass,
67 size_t obj_size,
68 uint age, bool tenured,
69 const PSPromotionLAB* lab) {
70 // Skip if memory allocation failed
71 if (new_obj != nullptr) {
72 const ParallelScavengeTracer* gc_tracer = PSScavenge::gc_tracer();
73
74 if (lab != nullptr) {
75 // Promotion of object through newly allocated PLAB
76 if (gc_tracer->should_report_promotion_in_new_plab_event()) {
77 size_t obj_bytes = obj_size * HeapWordSize;
78 size_t lab_size = lab->capacity();
79 gc_tracer->report_promotion_in_new_plab_event(klass, obj_bytes,
80 age, tenured, lab_size);
81 }
82 } else {
83 // Promotion of object directly to heap
84 if (gc_tracer->should_report_promotion_outside_plab_event()) {
85 size_t obj_bytes = obj_size * HeapWordSize;
86 gc_tracer->report_promotion_outside_plab_event(klass, obj_bytes,
87 age, tenured);
88 }
89 }
90 }
91 }
92
93 class PSPushContentsClosure: public BasicOopIterateClosure {
94 PSPromotionManager* _pm;
95 public:
96 PSPushContentsClosure(PSPromotionManager* pm) : BasicOopIterateClosure(PSScavenge::reference_processor()), _pm(pm) {}
97
98 template <typename T> void do_oop_nv(T* p) {
99 if (PSScavenge::should_scavenge(p)) {
100 _pm->claim_or_forward_depth(p);
101 }
102 }
103
104 virtual void do_oop(oop* p) { do_oop_nv(p); }
105 virtual void do_oop(narrowOop* p) { do_oop_nv(p); }
106 };
130 obj->oop_iterate_backwards(&pcc);
131 }
132 }
133
134 template<bool promote_immediately>
135 inline oop PSPromotionManager::copy_to_survivor_space(oop o) {
136 assert(should_scavenge(&o), "Sanity");
137
138 // NOTE! We must be very careful with any methods that access the mark
139 // in o. There may be multiple threads racing on it, and it may be forwarded
140 // at any time.
141 markWord m = o->mark();
142 if (!m.is_marked()) {
143 return copy_unmarked_to_survivor_space<promote_immediately>(o, m);
144 } else {
145 // Ensure any loads from the forwardee follow all changes that precede
146 // the release-cmpxchg that performed the forwarding, possibly in some
147 // other thread.
148 OrderAccess::acquire();
149 // Return the already installed forwardee.
150 return o->forwardee(m);
151 }
152 }
153
154 //
155 // This method is pretty bulky. It would be nice to split it up
156 // into smaller submethods, but we need to be careful not to hurt
157 // performance.
158 //
159 template<bool promote_immediately>
160 inline oop PSPromotionManager::copy_unmarked_to_survivor_space(oop o,
161 markWord test_mark) {
162 assert(should_scavenge(&o), "Sanity");
163
164 oop new_obj = nullptr;
165 bool new_obj_is_tenured = false;
166 // NOTE: With compact headers, it is not safe to load the Klass* from o, because
167 // that would access the mark-word, and the mark-word might change at any time by
168 // concurrent promotion. The promoted mark-word would point to the forwardee, which
169 // may not yet have completed copying. Therefore we must load the Klass* from
170 // the mark-word that we have already loaded. This is safe, because we have checked
171 // that this is not yet forwarded in the caller.
172 Klass* klass = o->forward_safe_klass(test_mark);
173 size_t new_obj_size = o->size_given_klass(klass);
174
175 // Find the objects age, MT safe.
176 uint age = (test_mark.has_displaced_mark_helper() /* o->has_displaced_mark() */) ?
177 test_mark.displaced_mark_helper().age() : test_mark.age();
178
179 if (!promote_immediately) {
180 // Try allocating obj in to-space (unless too old)
181 if (age < PSScavenge::tenuring_threshold()) {
182 new_obj = cast_to_oop(_young_lab.allocate(new_obj_size));
183 if (new_obj == nullptr && !_young_gen_is_full) {
184 // Do we allocate directly, or flush and refill?
185 if (new_obj_size > (YoungPLABSize / 2)) {
186 // Allocate this object directly
187 new_obj = cast_to_oop(young_space()->cas_allocate(new_obj_size));
188 promotion_trace_event(new_obj, klass, new_obj_size, age, false, nullptr);
189 } else {
190 // Flush and fill
191 _young_lab.flush();
192
193 HeapWord* lab_base = young_space()->cas_allocate(YoungPLABSize);
194 if (lab_base != nullptr) {
195 _young_lab.initialize(MemRegion(lab_base, YoungPLABSize));
196 // Try the young lab allocation again.
197 new_obj = cast_to_oop(_young_lab.allocate(new_obj_size));
198 promotion_trace_event(new_obj, klass, new_obj_size, age, false, &_young_lab);
199 } else {
200 _young_gen_is_full = true;
201 }
202 }
203 }
204 }
205 }
206
207 // Otherwise try allocating obj tenured
208 if (new_obj == nullptr) {
209 #ifndef PRODUCT
210 if (ParallelScavengeHeap::heap()->promotion_should_fail()) {
211 return oop_promotion_failed(o, test_mark);
212 }
213 #endif // #ifndef PRODUCT
214
215 new_obj = cast_to_oop(_old_lab.allocate(new_obj_size));
216 new_obj_is_tenured = true;
217
218 if (new_obj == nullptr) {
219 if (!_old_gen_is_full) {
220 // Do we allocate directly, or flush and refill?
221 if (new_obj_size > (OldPLABSize / 2)) {
222 // Allocate this object directly
223 new_obj = cast_to_oop(old_gen()->allocate(new_obj_size));
224 promotion_trace_event(new_obj, klass, new_obj_size, age, true, nullptr);
225 } else {
226 // Flush and fill
227 _old_lab.flush();
228
229 HeapWord* lab_base = old_gen()->allocate(OldPLABSize);
230 if(lab_base != nullptr) {
231 _old_lab.initialize(MemRegion(lab_base, OldPLABSize));
232 // Try the old lab allocation again.
233 new_obj = cast_to_oop(_old_lab.allocate(new_obj_size));
234 promotion_trace_event(new_obj, klass, new_obj_size, age, true, &_old_lab);
235 }
236 }
237 }
238
239 // This is the promotion failed test, and code handling.
240 // The code belongs here for two reasons. It is slightly
241 // different than the code below, and cannot share the
242 // CAS testing code. Keeping the code here also minimizes
243 // the impact on the common case fast path code.
244
245 if (new_obj == nullptr) {
246 _old_gen_is_full = true;
247 return oop_promotion_failed(o, test_mark);
248 }
249 }
250 }
251
252 assert(new_obj != nullptr, "allocation should have succeeded");
253
254 // Copy obj
255 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(o), cast_from_oop<HeapWord*>(new_obj), new_obj_size);
256
257 // Parallel GC claims with a release - so other threads might access this object
258 // after claiming and they should see the "completed" object.
259 if (UseCompactObjectHeaders) {
260 // The copy above is not atomic. Make sure we have seen the proper mark
261 // and re-install it into the copy, so that Klass* is guaranteed to be correct.
262 markWord mark = o->mark();
263 if (!mark.is_marked()) {
264 new_obj->set_mark(mark);
265 ContinuationGCSupport::transform_stack_chunk(new_obj);
266 } else {
267 // If we copied a mark-word that indicates 'forwarded' state, the object
268 // installation would not succeed. We cannot access Klass* anymore either.
269 // Skip the transformation.
270 }
271 } else {
272 ContinuationGCSupport::transform_stack_chunk(new_obj);
273 }
274
275 // Now we have to CAS in the header.
276 // Make copy visible to threads reading the forwardee.
277 oop forwardee = o->forward_to_atomic(new_obj, test_mark, memory_order_release);
278 if (forwardee == nullptr) { // forwardee is null when forwarding is successful
279 // We won any races, we "own" this object.
280 assert(new_obj == o->forwardee(), "Sanity");
281
282 // Increment age if obj still in new generation. Now that
283 // we're dealing with a markWord that cannot change, it is
284 // okay to use the non mt safe oop methods.
285 if (!new_obj_is_tenured) {
286 new_obj->incr_age();
287 assert(young_space()->contains(new_obj), "Attempt to push non-promoted obj");
288 }
289
290 // Do the size comparison first with new_obj_size, which we
291 // already have. Hopefully, only a few objects are larger than
292 // _min_array_size_for_chunking, and most of them will be arrays.
293 // So, the is->objArray() test would be very infrequent.
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