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25
26 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP
27 #define SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP
28
29 #include "gc/shenandoah/shenandoahMark.hpp"
30
31 #include "gc/shared/continuationGCSupport.inline.hpp"
32 #include "gc/shenandoah/shenandoahAsserts.hpp"
33 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
34 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
35 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
36 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp"
37 #include "gc/shenandoah/shenandoahStringDedup.inline.hpp"
38 #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
39 #include "gc/shenandoah/shenandoahUtils.hpp"
40 #include "memory/iterator.inline.hpp"
41 #include "oops/compressedOops.inline.hpp"
42 #include "oops/oop.inline.hpp"
43 #include "runtime/prefetch.inline.hpp"
44 #include "utilities/devirtualizer.inline.hpp"
45 #include "utilities/powerOfTwo.hpp"
46
47 template <StringDedupMode STRING_DEDUP>
48 void ShenandoahMark::dedup_string(oop obj, StringDedup::Requests* const req) {
49 if (STRING_DEDUP == ENQUEUE_DEDUP) {
50 if (ShenandoahStringDedup::is_candidate(obj)) {
51 req->add(obj);
52 }
53 } else if (STRING_DEDUP == ALWAYS_DEDUP) {
54 if (ShenandoahStringDedup::is_string_candidate(obj) &&
55 !ShenandoahStringDedup::dedup_requested(obj)) {
56 req->add(obj);
57 }
58 }
59 }
60
61 template <class T, ShenandoahGenerationType GENERATION, StringDedupMode STRING_DEDUP>
62 void ShenandoahMark::do_task(ShenandoahObjToScanQueue* q, T* cl, ShenandoahLiveData* live_data, StringDedup::Requests* const req, ShenandoahMarkTask* task, uint worker_id) {
63 oop obj = task->obj();
64
65 // TODO: This will push array chunks into the mark queue with no regard for
66 // generations. I don't think it will break anything, but the young generation
67 // scan might end up processing some old generation array chunks.
68
69 shenandoah_assert_not_forwarded(nullptr, obj);
70 shenandoah_assert_marked(nullptr, obj);
71 shenandoah_assert_not_in_cset_except(nullptr, obj, ShenandoahHeap::heap()->cancelled_gc());
72
73 // Are we in weak subgraph scan?
74 bool weak = task->is_weak();
75 cl->set_weak(weak);
76
77 if (task->is_not_chunked()) {
78 if (obj->is_instance()) {
79 // Case 1: Normal oop, process as usual.
80 if (ContinuationGCSupport::relativize_stack_chunk(obj)) {
81 // Loom doesn't support mixing of weak marking and strong marking of
82 // stack chunks.
83 cl->set_weak(false);
84 }
85
86 obj->oop_iterate(cl);
87 dedup_string<STRING_DEDUP>(obj, req);
88 } else if (obj->is_objArray()) {
89 // Case 2: Object array instance and no chunk is set. Must be the first
90 // time we visit it, start the chunked processing.
91 do_chunked_array_start<T>(q, cl, obj, weak);
92 } else {
93 // Case 3: Primitive array. Do nothing, no oops there. We use the same
94 // performance tweak TypeArrayKlass::oop_oop_iterate_impl is using:
95 // We skip iterating over the klass pointer since we know that
96 // Universe::TypeArrayKlass never moves.
97 assert (obj->is_typeArray(), "should be type array");
98 }
99 // Count liveness the last: push the outstanding work to the queues first
100 // Avoid double-counting objects that are visited twice due to upgrade
101 // from final- to strong mark.
102 if (task->count_liveness()) {
103 count_liveness<GENERATION>(live_data, obj, worker_id);
104 }
105 } else {
106 // Case 4: Array chunk, has sensible chunk id. Process it.
107 do_chunked_array<T>(q, cl, obj, task->chunk(), task->pow(), weak);
108 }
109 }
110
111 template <ShenandoahGenerationType GENERATION>
112 inline void ShenandoahMark::count_liveness(ShenandoahLiveData* live_data, oop obj, uint worker_id) {
113 const ShenandoahHeap* const heap = ShenandoahHeap::heap();
114 const size_t region_idx = heap->heap_region_index_containing(obj);
115 ShenandoahHeapRegion* const region = heap->get_region(region_idx);
116 const size_t size = obj->size();
117
118 // Age census for objects in the young generation
119 if (GENERATION == YOUNG || (GENERATION == GLOBAL && region->is_young())) {
120 assert(heap->mode()->is_generational(), "Only if generational");
121 if (ShenandoahGenerationalAdaptiveTenuring && !ShenandoahGenerationalCensusAtEvac) {
122 assert(region->is_young(), "Only for young objects");
123 uint age = ShenandoahHeap::get_object_age(obj);
124 CENSUS_NOISE(heap->age_census()->add(age, region->age(), region->youth(), size, worker_id);)
125 NO_CENSUS_NOISE(heap->age_census()->add(age, region->age(), size, worker_id);)
126 }
127 }
128
129 if (!region->is_humongous_start()) {
130 assert(!region->is_humongous(), "Cannot have continuations here");
131 assert(region->is_affiliated(), "Do not count live data within Free Regular Region " SIZE_FORMAT, region_idx);
132 ShenandoahLiveData cur = live_data[region_idx];
133 size_t new_val = size + cur;
134 if (new_val >= SHENANDOAH_LIVEDATA_MAX) {
135 // overflow, flush to region data
136 region->increase_live_data_gc_words(new_val);
137 live_data[region_idx] = 0;
138 } else {
139 // still good, remember in locals
140 live_data[region_idx] = (ShenandoahLiveData) new_val;
141 }
142 } else {
143 shenandoah_assert_in_correct_region(nullptr, obj);
144 size_t num_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
145
146 assert(region->is_affiliated(), "Do not count live data within FREE Humongous Start Region " SIZE_FORMAT, region_idx);
147 for (size_t i = region_idx; i < region_idx + num_regions; i++) {
148 ShenandoahHeapRegion* chain_reg = heap->get_region(i);
149 assert(chain_reg->is_humongous(), "Expecting a humongous region");
150 assert(chain_reg->is_affiliated(), "Do not count live data within FREE Humongous Continuation Region " SIZE_FORMAT, i);
151 chain_reg->increase_live_data_gc_words(chain_reg->used() >> LogHeapWordSize);
152 }
153 }
154 }
155
156 template <class T>
157 inline void ShenandoahMark::do_chunked_array_start(ShenandoahObjToScanQueue* q, T* cl, oop obj, bool weak) {
158 assert(obj->is_objArray(), "expect object array");
159 objArrayOop array = objArrayOop(obj);
160 int len = array->length();
161
162 // Mark objArray klass metadata
163 if (Devirtualizer::do_metadata(cl)) {
164 Devirtualizer::do_klass(cl, array->klass());
165 }
166
167 if (len <= (int) ObjArrayMarkingStride*2) {
168 // A few slices only, process directly
169 array->oop_iterate_range(cl, 0, len);
170 } else {
171 int bits = log2i_graceful(len);
172 // Compensate for non-power-of-two arrays, cover the array in excess:
173 if (len != (1 << bits)) bits++;
174
175 // Only allow full chunks on the queue. This frees do_chunked_array() from checking from/to
176 // boundaries against array->length(), touching the array header on every chunk.
177 //
178 // To do this, we cut the prefix in full-sized chunks, and submit them on the queue.
179 // If the array is not divided in chunk sizes, then there would be an irregular tail,
180 // which we will process separately.
181
182 int last_idx = 0;
183
184 int chunk = 1;
185 int pow = bits;
186
187 // Handle overflow
188 if (pow >= 31) {
189 assert (pow == 31, "sanity");
190 pow--;
191 chunk = 2;
192 last_idx = (1 << pow);
193 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, 1, pow));
194 assert(pushed, "overflow queue should always succeed pushing");
195 }
196
197 // Split out tasks, as suggested in ShenandoahMarkTask docs. Record the last
198 // successful right boundary to figure out the irregular tail.
199 while ((1 << pow) > (int)ObjArrayMarkingStride &&
200 (chunk*2 < ShenandoahMarkTask::chunk_size())) {
201 pow--;
202 int left_chunk = chunk*2 - 1;
203 int right_chunk = chunk*2;
204 int left_chunk_end = left_chunk * (1 << pow);
205 if (left_chunk_end < len) {
206 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, left_chunk, pow));
207 assert(pushed, "overflow queue should always succeed pushing");
208 chunk = right_chunk;
209 last_idx = left_chunk_end;
210 } else {
211 chunk = left_chunk;
212 }
213 }
214
215 // Process the irregular tail, if present
216 int from = last_idx;
217 if (from < len) {
218 array->oop_iterate_range(cl, from, len);
219 }
220 }
221 }
222
223 template <class T>
224 inline void ShenandoahMark::do_chunked_array(ShenandoahObjToScanQueue* q, T* cl, oop obj, int chunk, int pow, bool weak) {
225 assert(obj->is_objArray(), "expect object array");
226 objArrayOop array = objArrayOop(obj);
227
228 assert (ObjArrayMarkingStride > 0, "sanity");
229
230 // Split out tasks, as suggested in ShenandoahMarkTask docs. Avoid pushing tasks that
231 // are known to start beyond the array.
232 while ((1 << pow) > (int)ObjArrayMarkingStride && (chunk*2 < ShenandoahMarkTask::chunk_size())) {
233 pow--;
234 chunk *= 2;
235 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, chunk - 1, pow));
236 assert(pushed, "overflow queue should always succeed pushing");
237 }
238
239 int chunk_size = 1 << pow;
240
241 int from = (chunk - 1) * chunk_size;
242 int to = chunk * chunk_size;
243
244 #ifdef ASSERT
245 int len = array->length();
246 assert (0 <= from && from < len, "from is sane: %d/%d", from, len);
247 assert (0 < to && to <= len, "to is sane: %d/%d", to, len);
248 #endif
249
250 array->oop_iterate_range(cl, from, to);
251 }
252
253 template <ShenandoahGenerationType GENERATION>
254 class ShenandoahSATBBufferClosure : public SATBBufferClosure {
255 private:
256 ShenandoahObjToScanQueue* _queue;
257 ShenandoahObjToScanQueue* _old_queue;
258 ShenandoahHeap* _heap;
259 ShenandoahMarkingContext* const _mark_context;
260 public:
261 ShenandoahSATBBufferClosure(ShenandoahObjToScanQueue* q, ShenandoahObjToScanQueue* old_q) :
262 _queue(q),
263 _old_queue(old_q),
264 _heap(ShenandoahHeap::heap()),
265 _mark_context(_heap->marking_context())
266 {
267 }
268
269 void do_buffer(void **buffer, size_t size) {
270 assert(size == 0 || !_heap->has_forwarded_objects() || _heap->is_concurrent_old_mark_in_progress(), "Forwarded objects are not expected here");
271 for (size_t i = 0; i < size; ++i) {
272 oop *p = (oop *) &buffer[i];
273 ShenandoahMark::mark_through_ref<oop, GENERATION>(p, _queue, _old_queue, _mark_context, false);
274 }
275 }
276 };
277
278 template<ShenandoahGenerationType GENERATION>
279 bool ShenandoahMark::in_generation(ShenandoahHeap* const heap, oop obj) {
280 // Each in-line expansion of in_generation() resolves GENERATION at compile time.
281 if (GENERATION == YOUNG) {
282 return heap->is_in_young(obj);
283 } else if (GENERATION == OLD) {
284 return heap->is_in_old(obj);
285 } else if (GENERATION == GLOBAL || GENERATION == NON_GEN) {
286 return true;
287 } else {
288 return false;
289 }
290 }
291
292 template<class T, ShenandoahGenerationType GENERATION>
293 inline void ShenandoahMark::mark_through_ref(T *p, ShenandoahObjToScanQueue* q, ShenandoahObjToScanQueue* old_q, ShenandoahMarkingContext* const mark_context, bool weak) {
294 // Note: This is a very hot code path, so the code should be conditional on GENERATION template
295 // parameter where possible, in order to generate the most efficient code.
296
297 T o = RawAccess<>::oop_load(p);
298 if (!CompressedOops::is_null(o)) {
299 oop obj = CompressedOops::decode_not_null(o);
300
301 ShenandoahHeap* heap = ShenandoahHeap::heap();
302 shenandoah_assert_not_forwarded(p, obj);
303 shenandoah_assert_not_in_cset_except(p, obj, heap->cancelled_gc());
304 if (in_generation<GENERATION>(heap, obj)) {
305 mark_ref(q, mark_context, weak, obj);
306 shenandoah_assert_marked(p, obj);
307 // TODO: As implemented herein, GLOBAL collections reconstruct the card table during GLOBAL concurrent
308 // marking. Note that the card table is cleaned at init_mark time so it needs to be reconstructed to support
309 // future young-gen collections. It might be better to reconstruct card table in a different phase. We could
310 // either mark all live memory as dirty, or could use the GLOBAL update-refs scanning of pointers to determine
311 // precisely which cards to flag as dirty.
312 if (GENERATION == YOUNG && heap->is_in_old(p)) {
313 // Mark card as dirty because remembered set scanning still finds interesting pointer.
314 heap->mark_card_as_dirty((HeapWord*)p);
315 } else if (GENERATION == GLOBAL && heap->is_in_old(p) && heap->is_in_young(obj)) {
316 // Mark card as dirty because GLOBAL marking finds interesting pointer.
317 heap->mark_card_as_dirty((HeapWord*)p);
318 }
319 } else if (old_q != nullptr) {
320 // Young mark, bootstrapping old_q or concurrent with old_q marking.
321 mark_ref(old_q, mark_context, weak, obj);
322 shenandoah_assert_marked(p, obj);
323 } else if (GENERATION == OLD) {
324 // Old mark, found a young pointer.
325 // TODO: Rethink this: may be redundant with dirtying of cards identified during young-gen remembered set scanning
326 // and by mutator write barriers. Assert
327 if (heap->is_in(p)) {
328 assert(heap->is_in_young(obj), "Expected young object.");
329 heap->mark_card_as_dirty(p);
330 }
331 }
332 }
333 }
334
335 inline void ShenandoahMark::mark_ref(ShenandoahObjToScanQueue* q,
336 ShenandoahMarkingContext* const mark_context,
337 bool weak, oop obj) {
338 bool skip_live = false;
339 bool marked;
340 if (weak) {
341 marked = mark_context->mark_weak(obj);
342 } else {
343 marked = mark_context->mark_strong(obj, /* was_upgraded = */ skip_live);
344 }
345 if (marked) {
346 bool pushed = q->push(ShenandoahMarkTask(obj, skip_live, weak));
347 assert(pushed, "overflow queue should always succeed pushing");
348 }
349 }
350
351 ShenandoahObjToScanQueueSet* ShenandoahMark::task_queues() const {
352 return _task_queues;
353 }
354
355 ShenandoahObjToScanQueue* ShenandoahMark::get_queue(uint index) const {
356 return _task_queues->queue(index);
357 }
358
359 ShenandoahObjToScanQueue* ShenandoahMark::get_old_queue(uint index) const {
360 if (_old_gen_task_queues != nullptr) {
361 return _old_gen_task_queues->queue(index);
362 }
363 return nullptr;
364 }
365
366 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP