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5 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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15 * accompanied this code).
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26
27 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP
28 #define SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP
29
30 #include "gc/shenandoah/shenandoahMark.hpp"
31
32 #include "gc/shared/continuationGCSupport.inline.hpp"
33 #include "gc/shenandoah/shenandoahAgeCensus.hpp"
34 #include "gc/shenandoah/shenandoahAsserts.hpp"
35 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp"
36 #include "gc/shenandoah/shenandoahClosures.inline.hpp"
37 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
38 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp"
39 #include "gc/shenandoah/shenandoahOldGeneration.hpp"
40 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp"
41 #include "gc/shenandoah/shenandoahStringDedup.inline.hpp"
42 #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
43 #include "gc/shenandoah/shenandoahUtils.hpp"
44 #include "memory/iterator.inline.hpp"
45 #include "oops/compressedOops.inline.hpp"
46 #include "oops/oop.inline.hpp"
47 #include "runtime/prefetch.inline.hpp"
48 #include "utilities/devirtualizer.inline.hpp"
49 #include "utilities/powerOfTwo.hpp"
50
51 template <StringDedupMode STRING_DEDUP>
52 void ShenandoahMark::dedup_string(oop obj, StringDedup::Requests* const req) {
53 if (STRING_DEDUP == ENQUEUE_DEDUP) {
54 if (ShenandoahStringDedup::is_candidate(obj)) {
55 req->add(obj);
56 }
57 } else if (STRING_DEDUP == ALWAYS_DEDUP) {
58 if (ShenandoahStringDedup::is_string_candidate(obj) &&
59 !ShenandoahStringDedup::dedup_requested(obj)) {
60 req->add(obj);
61 }
62 }
63 }
64
65 template <class T, ShenandoahGenerationType GENERATION, StringDedupMode STRING_DEDUP>
66 void ShenandoahMark::do_task(ShenandoahObjToScanQueue* q, T* cl, ShenandoahLiveData* live_data, StringDedup::Requests* const req, ShenandoahMarkTask* task, uint worker_id) {
67 oop obj = task->obj();
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 ShenandoahAgeCensus* const census = ShenandoahGenerationalHeap::heap()->age_census();
125 CENSUS_NOISE(census->add(age, region->age(), region->youth(), size, worker_id);)
126 NO_CENSUS_NOISE(census->add(age, region->age(), size, worker_id);)
127 }
128 }
129
130 if (!region->is_humongous_start()) {
131 assert(!region->is_humongous(), "Cannot have continuations here");
132 assert(region->is_affiliated(), "Do not count live data within Free Regular Region %zu", region_idx);
133 ShenandoahLiveData cur = live_data[region_idx];
134 size_t new_val = size + cur;
135 if (new_val >= SHENANDOAH_LIVEDATA_MAX) {
136 // overflow, flush to region data
137 region->increase_live_data_gc_words(new_val);
138 live_data[region_idx] = 0;
139 } else {
140 // still good, remember in locals
141 live_data[region_idx] = (ShenandoahLiveData) new_val;
142 }
143 } else {
144 shenandoah_assert_in_correct_region(nullptr, obj);
145 size_t num_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize);
146
147 assert(region->is_affiliated(), "Do not count live data within FREE Humongous Start Region %zu", region_idx);
148 for (size_t i = region_idx; i < region_idx + num_regions; i++) {
149 ShenandoahHeapRegion* chain_reg = heap->get_region(i);
150 assert(chain_reg->is_humongous(), "Expecting a humongous region");
151 assert(chain_reg->is_affiliated(), "Do not count live data within FREE Humongous Continuation Region %zu", i);
152 chain_reg->increase_live_data_gc_words(chain_reg->used() >> LogHeapWordSize);
153 }
154 }
155 }
156
157 template <class T>
158 inline void ShenandoahMark::do_chunked_array_start(ShenandoahObjToScanQueue* q, T* cl, oop obj, bool weak) {
159 assert(obj->is_objArray(), "expect object array");
160 objArrayOop array = objArrayOop(obj);
161 int len = array->length();
162
163 // Mark objArray klass metadata
164 if (Devirtualizer::do_metadata(cl)) {
165 Devirtualizer::do_klass(cl, array->klass());
166 }
167
168 if (len <= (int) ObjArrayMarkingStride*2) {
169 // A few slices only, process directly
170 array->oop_iterate_range(cl, 0, len);
171 } else {
172 int bits = log2i_graceful(len);
173 // Compensate for non-power-of-two arrays, cover the array in excess:
174 if (len != (1 << bits)) bits++;
175
176 // Only allow full chunks on the queue. This frees do_chunked_array() from checking from/to
177 // boundaries against array->length(), touching the array header on every chunk.
178 //
179 // To do this, we cut the prefix in full-sized chunks, and submit them on the queue.
180 // If the array is not divided in chunk sizes, then there would be an irregular tail,
181 // which we will process separately.
182
183 int last_idx = 0;
184
185 int chunk = 1;
186 int pow = bits;
187
188 // Handle overflow
189 if (pow >= 31) {
190 assert (pow == 31, "sanity");
191 pow--;
192 chunk = 2;
193 last_idx = (1 << pow);
194 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, 1, pow));
195 assert(pushed, "overflow queue should always succeed pushing");
196 }
197
198 // Split out tasks, as suggested in ShenandoahMarkTask docs. Record the last
199 // successful right boundary to figure out the irregular tail.
200 while ((1 << pow) > (int)ObjArrayMarkingStride &&
201 (chunk*2 < ShenandoahMarkTask::chunk_size())) {
202 pow--;
203 int left_chunk = chunk*2 - 1;
204 int right_chunk = chunk*2;
205 int left_chunk_end = left_chunk * (1 << pow);
206 if (left_chunk_end < len) {
207 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, left_chunk, pow));
208 assert(pushed, "overflow queue should always succeed pushing");
209 chunk = right_chunk;
210 last_idx = left_chunk_end;
211 } else {
212 chunk = left_chunk;
213 }
214 }
215
216 // Process the irregular tail, if present
217 int from = last_idx;
218 if (from < len) {
219 array->oop_iterate_range(cl, from, len);
220 }
221 }
222 }
223
224 template <class T>
225 inline void ShenandoahMark::do_chunked_array(ShenandoahObjToScanQueue* q, T* cl, oop obj, int chunk, int pow, bool weak) {
226 assert(obj->is_objArray(), "expect object array");
227 objArrayOop array = objArrayOop(obj);
228
229 assert (ObjArrayMarkingStride > 0, "sanity");
230
231 // Split out tasks, as suggested in ShenandoahMarkTask docs. Avoid pushing tasks that
232 // are known to start beyond the array.
233 while ((1 << pow) > (int)ObjArrayMarkingStride && (chunk*2 < ShenandoahMarkTask::chunk_size())) {
234 pow--;
235 chunk *= 2;
236 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, chunk - 1, pow));
237 assert(pushed, "overflow queue should always succeed pushing");
238 }
239
240 int chunk_size = 1 << pow;
241
242 int from = (chunk - 1) * chunk_size;
243 int to = chunk * chunk_size;
244
245 #ifdef ASSERT
246 int len = array->length();
247 assert (0 <= from && from < len, "from is sane: %d/%d", from, len);
248 assert (0 < to && to <= len, "to is sane: %d/%d", to, len);
249 #endif
250
251 array->oop_iterate_range(cl, from, to);
252 }
253
254 template <ShenandoahGenerationType GENERATION>
255 class ShenandoahSATBBufferClosure : public SATBBufferClosure {
256 private:
257 ShenandoahObjToScanQueue* _queue;
258 ShenandoahObjToScanQueue* _old_queue;
259 ShenandoahHeap* _heap;
260 ShenandoahMarkingContext* const _mark_context;
261 public:
262 ShenandoahSATBBufferClosure(ShenandoahObjToScanQueue* q, ShenandoahObjToScanQueue* old_q) :
263 _queue(q),
264 _old_queue(old_q),
265 _heap(ShenandoahHeap::heap()),
266 _mark_context(_heap->marking_context())
267 {
268 }
269
270 void do_buffer(void **buffer, size_t size) {
271 assert(size == 0 || !_heap->has_forwarded_objects() || _heap->is_concurrent_old_mark_in_progress(), "Forwarded objects are not expected here");
272 for (size_t i = 0; i < size; ++i) {
273 oop *p = (oop *) &buffer[i];
274 ShenandoahMark::mark_through_ref<oop, GENERATION>(p, _queue, _old_queue, _mark_context, false);
275 }
276 }
277 };
278
279 template<ShenandoahGenerationType GENERATION>
280 bool ShenandoahMark::in_generation(ShenandoahHeap* const heap, oop obj) {
281 // Each in-line expansion of in_generation() resolves GENERATION at compile time.
282 if (GENERATION == YOUNG) {
283 return heap->is_in_young(obj);
284 }
285
286 if (GENERATION == OLD) {
287 return heap->is_in_old(obj);
288 }
289
290 assert((GENERATION == GLOBAL || GENERATION == NON_GEN), "Unexpected generation type");
291 assert(heap->is_in(obj), "Object must be in heap");
292 return true;
293 }
294
295 template<class T, ShenandoahGenerationType GENERATION>
296 inline void ShenandoahMark::mark_through_ref(T *p, ShenandoahObjToScanQueue* q, ShenandoahObjToScanQueue* old_q, ShenandoahMarkingContext* const mark_context, bool weak) {
297 // Note: This is a very hot code path, so the code should be conditional on GENERATION template
298 // parameter where possible, in order to generate the most efficient code.
299
300 T o = RawAccess<>::oop_load(p);
301 if (!CompressedOops::is_null(o)) {
302 oop obj = CompressedOops::decode_not_null(o);
303
304 ShenandoahGenerationalHeap* heap = ShenandoahGenerationalHeap::heap();
305 shenandoah_assert_not_forwarded(p, obj);
306 shenandoah_assert_not_in_cset_except(p, obj, heap->cancelled_gc());
307 if (in_generation<GENERATION>(heap, obj)) {
308 mark_ref(q, mark_context, weak, obj);
309 shenandoah_assert_marked(p, obj);
310 if (GENERATION == YOUNG && heap->is_in_old(p)) {
311 // Mark card as dirty because remembered set scanning still finds interesting pointer.
312 heap->old_generation()->mark_card_as_dirty((HeapWord*)p);
313 } else if (GENERATION == GLOBAL && heap->is_in_old(p) && heap->is_in_young(obj)) {
314 // Mark card as dirty because GLOBAL marking finds interesting pointer.
315 heap->old_generation()->mark_card_as_dirty((HeapWord*)p);
316 }
317 } else if (old_q != nullptr) {
318 // Young mark, bootstrapping old_q or concurrent with old_q marking.
319 mark_ref(old_q, mark_context, weak, obj);
320 shenandoah_assert_marked(p, obj);
321 } else if (GENERATION == OLD) {
322 // Old mark, found a young pointer.
323 if (heap->is_in(p)) {
324 assert(heap->is_in_young(obj), "Expected young object.");
325 heap->old_generation()->mark_card_as_dirty(p);
326 }
327 }
328 }
329 }
330
331 template<>
332 inline void ShenandoahMark::mark_through_ref<oop, ShenandoahGenerationType::NON_GEN>(oop *p, ShenandoahObjToScanQueue* q, ShenandoahObjToScanQueue* old_q, ShenandoahMarkingContext* const mark_context, bool weak) {
333 mark_non_generational_ref(p, q, mark_context, weak);
334 }
335
336 template<>
337 inline void ShenandoahMark::mark_through_ref<narrowOop, ShenandoahGenerationType::NON_GEN>(narrowOop *p, ShenandoahObjToScanQueue* q, ShenandoahObjToScanQueue* old_q, ShenandoahMarkingContext* const mark_context, bool weak) {
338 mark_non_generational_ref(p, q, mark_context, weak);
339 }
340
341 template<class T>
342 inline void ShenandoahMark::mark_non_generational_ref(T* p, ShenandoahObjToScanQueue* q,
343 ShenandoahMarkingContext* const mark_context, bool weak) {
344 oop o = RawAccess<>::oop_load(p);
345 if (!CompressedOops::is_null(o)) {
346 oop obj = CompressedOops::decode_not_null(o);
347
348 shenandoah_assert_not_forwarded(p, obj);
349 shenandoah_assert_not_in_cset_except(p, obj, ShenandoahHeap::heap()->cancelled_gc());
350
351 mark_ref(q, mark_context, weak, obj);
352
353 shenandoah_assert_marked(p, obj);
354 }
355 }
356
357 inline void ShenandoahMark::mark_ref(ShenandoahObjToScanQueue* q,
358 ShenandoahMarkingContext* const mark_context,
359 bool weak, oop obj) {
360 bool skip_live = false;
361 bool marked;
362 if (weak) {
363 marked = mark_context->mark_weak(obj);
364 } else {
365 marked = mark_context->mark_strong(obj, /* was_upgraded = */ skip_live);
366 }
367 if (marked) {
368 bool pushed = q->push(ShenandoahMarkTask(obj, skip_live, weak));
369 assert(pushed, "overflow queue should always succeed pushing");
370 }
371 }
372
373 ShenandoahObjToScanQueueSet* ShenandoahMark::task_queues() const {
374 return _task_queues;
375 }
376
377 ShenandoahObjToScanQueue* ShenandoahMark::get_queue(uint index) const {
378 return _task_queues->queue(index);
379 }
380
381 ShenandoahObjToScanQueue* ShenandoahMark::get_old_queue(uint index) const {
382 if (_old_gen_task_queues != nullptr) {
383 return _old_gen_task_queues->queue(index);
384 }
385 return nullptr;
386 }
387
388 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP