1 /*
2 * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
8 *
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
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16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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23 */
24
25 #ifndef SHARE_GC_G1_HEAPREGION_INLINE_HPP
26 #define SHARE_GC_G1_HEAPREGION_INLINE_HPP
27
28 #include "gc/g1/g1BlockOffsetTable.inline.hpp"
29 #include "gc/g1/g1CollectedHeap.inline.hpp"
30 #include "gc/g1/g1ConcurrentMarkBitMap.inline.hpp"
31 #include "gc/g1/g1Predictions.hpp"
32 #include "gc/g1/heapRegion.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/atomic.hpp"
35 #include "runtime/prefetch.inline.hpp"
36 #include "utilities/align.hpp"
37 #include "utilities/globalDefinitions.hpp"
38
39 inline HeapWord* HeapRegion::allocate_impl(size_t min_word_size,
40 size_t desired_word_size,
41 size_t* actual_size) {
42 HeapWord* obj = top();
43 size_t available = pointer_delta(end(), obj);
44 size_t want_to_allocate = MIN2(available, desired_word_size);
45 if (want_to_allocate >= min_word_size) {
46 HeapWord* new_top = obj + want_to_allocate;
47 set_top(new_top);
48 assert(is_object_aligned(obj) && is_object_aligned(new_top), "checking alignment");
49 *actual_size = want_to_allocate;
50 return obj;
51 } else {
52 return NULL;
53 }
54 }
55
56 inline HeapWord* HeapRegion::par_allocate_impl(size_t min_word_size,
57 size_t desired_word_size,
58 size_t* actual_size) {
59 do {
60 HeapWord* obj = top();
61 size_t available = pointer_delta(end(), obj);
62 size_t want_to_allocate = MIN2(available, desired_word_size);
63 if (want_to_allocate >= min_word_size) {
64 HeapWord* new_top = obj + want_to_allocate;
65 HeapWord* result = Atomic::cmpxchg(new_top, &_top, obj);
66 // result can be one of two:
67 // the old top value: the exchange succeeded
68 // otherwise: the new value of the top is returned.
69 if (result == obj) {
70 assert(is_object_aligned(obj) && is_object_aligned(new_top), "checking alignment");
71 *actual_size = want_to_allocate;
72 return obj;
73 }
74 } else {
75 return NULL;
76 }
77 } while (true);
78 }
79
80 inline HeapWord* HeapRegion::allocate(size_t min_word_size,
81 size_t desired_word_size,
82 size_t* actual_size) {
83 HeapWord* res = allocate_impl(min_word_size, desired_word_size, actual_size);
84 if (res != NULL) {
85 _bot_part.alloc_block(res, *actual_size);
86 }
87 return res;
88 }
89
90 inline HeapWord* HeapRegion::allocate(size_t word_size) {
91 size_t temp;
92 return allocate(word_size, word_size, &temp);
93 }
94
95 inline HeapWord* HeapRegion::par_allocate(size_t word_size) {
96 size_t temp;
97 return par_allocate(word_size, word_size, &temp);
98 }
99
100 // Because of the requirement of keeping "_offsets" up to date with the
101 // allocations, we sequentialize these with a lock. Therefore, best if
102 // this is used for larger LAB allocations only.
103 inline HeapWord* HeapRegion::par_allocate(size_t min_word_size,
104 size_t desired_word_size,
105 size_t* actual_size) {
106 MutexLocker x(&_par_alloc_lock);
107 return allocate(min_word_size, desired_word_size, actual_size);
108 }
109
110 inline HeapWord* HeapRegion::block_start(const void* p) {
111 return _bot_part.block_start(p);
112 }
113
114 inline HeapWord* HeapRegion::block_start_const(const void* p) const {
115 return _bot_part.block_start_const(p);
116 }
117
118 inline bool HeapRegion::is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const {
119 HeapWord* addr = (HeapWord*) obj;
120
121 assert(addr < top(), "must be");
122 assert(!is_closed_archive(),
123 "Closed archive regions should not have references into other regions");
124 assert(!is_humongous(), "Humongous objects not handled here");
125 bool obj_is_dead = is_obj_dead(obj, prev_bitmap);
126
127 if (ClassUnloadingWithConcurrentMark && obj_is_dead) {
128 assert(!block_is_obj(addr), "must be");
129 *size = block_size_using_bitmap(addr, prev_bitmap);
130 } else {
131 assert(block_is_obj(addr), "must be");
132 *size = obj->size();
133 }
134 return obj_is_dead;
135 }
136
137 inline bool HeapRegion::block_is_obj(const HeapWord* p) const {
138 G1CollectedHeap* g1h = G1CollectedHeap::heap();
139
140 if (!this->is_in(p)) {
141 assert(is_continues_humongous(), "This case can only happen for humongous regions");
142 return (p == humongous_start_region()->bottom());
143 }
144 if (ClassUnloadingWithConcurrentMark) {
145 return !g1h->is_obj_dead(oop(p), this);
146 }
147 return p < top();
148 }
149
150 inline size_t HeapRegion::block_size_using_bitmap(const HeapWord* addr, const G1CMBitMap* const prev_bitmap) const {
151 assert(ClassUnloadingWithConcurrentMark,
152 "All blocks should be objects if class unloading isn't used, so this method should not be called. "
153 "HR: [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ") "
154 "addr: " PTR_FORMAT,
155 p2i(bottom()), p2i(top()), p2i(end()), p2i(addr));
156
157 // Old regions' dead objects may have dead classes
158 // We need to find the next live object using the bitmap
159 HeapWord* next = prev_bitmap->get_next_marked_addr(addr, prev_top_at_mark_start());
160
161 assert(next > addr, "must get the next live object");
162 return pointer_delta(next, addr);
163 }
164
165 inline bool HeapRegion::is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const {
166 assert(is_in_reserved(obj), "Object " PTR_FORMAT " must be in region", p2i(obj));
167 return !obj_allocated_since_prev_marking(obj) &&
168 !prev_bitmap->is_marked((HeapWord*)obj) &&
169 !is_open_archive();
170 }
171
172 inline size_t HeapRegion::block_size(const HeapWord *addr) const {
173 if (addr == top()) {
174 return pointer_delta(end(), addr);
175 }
176
177 if (block_is_obj(addr)) {
178 return oop(addr)->size();
179 }
180
181 return block_size_using_bitmap(addr, G1CollectedHeap::heap()->concurrent_mark()->prev_mark_bitmap());
182 }
183
184 inline void HeapRegion::complete_compaction() {
185 // Reset space and bot after compaction is complete if needed.
186 reset_after_compaction();
187 if (is_empty()) {
188 reset_bot();
189 }
190
191 // After a compaction the mark bitmap is invalid, so we must
192 // treat all objects as being inside the unmarked area.
193 zero_marked_bytes();
194 init_top_at_mark_start();
195
196 // Clear unused heap memory in debug builds.
197 if (ZapUnusedHeapArea) {
198 mangle_unused_area();
199 }
200 }
201
202 template<typename ApplyToMarkedClosure>
203 inline void HeapRegion::apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure) {
204 HeapWord* limit = top();
205 HeapWord* next_addr = bottom();
206
207 while (next_addr < limit) {
208 Prefetch::write(next_addr, PrefetchScanIntervalInBytes);
209 // This explicit is_marked check is a way to avoid
210 // some extra work done by get_next_marked_addr for
211 // the case where next_addr is marked.
212 if (bitmap->is_marked(next_addr)) {
213 oop current = oop(next_addr);
214 next_addr += closure->apply(current);
215 } else {
216 next_addr = bitmap->get_next_marked_addr(next_addr, limit);
217 }
218 }
219
220 assert(next_addr == limit, "Should stop the scan at the limit.");
221 }
222
223 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t min_word_size,
224 size_t desired_word_size,
225 size_t* actual_word_size) {
226 assert(is_young(), "we can only skip BOT updates on young regions");
227 return par_allocate_impl(min_word_size, desired_word_size, actual_word_size);
228 }
229
230 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
231 size_t temp;
232 return allocate_no_bot_updates(word_size, word_size, &temp);
233 }
234
235 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t min_word_size,
236 size_t desired_word_size,
237 size_t* actual_word_size) {
238 assert(is_young(), "we can only skip BOT updates on young regions");
239 return allocate_impl(min_word_size, desired_word_size, actual_word_size);
240 }
241
242 inline void HeapRegion::note_start_of_marking() {
243 _next_marked_bytes = 0;
244 _next_top_at_mark_start = top();
245 }
246
247 inline void HeapRegion::note_end_of_marking() {
248 _prev_top_at_mark_start = _next_top_at_mark_start;
249 _next_top_at_mark_start = bottom();
250 _prev_marked_bytes = _next_marked_bytes;
251 _next_marked_bytes = 0;
252 }
253
254 inline bool HeapRegion::in_collection_set() const {
255 return G1CollectedHeap::heap()->is_in_cset(this);
256 }
257
258 template <class Closure, bool is_gc_active>
259 HeapWord* HeapRegion::do_oops_on_memregion_in_humongous(MemRegion mr,
260 Closure* cl,
261 G1CollectedHeap* g1h) {
262 assert(is_humongous(), "precondition");
263 HeapRegion* sr = humongous_start_region();
264 oop obj = oop(sr->bottom());
265
266 // If concurrent and klass_or_null is NULL, then space has been
267 // allocated but the object has not yet been published by setting
268 // the klass. That can only happen if the card is stale. However,
269 // we've already set the card clean, so we must return failure,
270 // since the allocating thread could have performed a write to the
271 // card that might be missed otherwise.
272 if (!is_gc_active && (obj->klass_or_null_acquire() == NULL)) {
273 return NULL;
274 }
275
276 // We have a well-formed humongous object at the start of sr.
277 // Only filler objects follow a humongous object in the containing
278 // regions, and we can ignore those. So only process the one
279 // humongous object.
280 if (g1h->is_obj_dead(obj, sr)) {
281 // The object is dead. There can be no other object in this region, so return
282 // the end of that region.
283 return end();
284 }
285 if (obj->is_objArray() || (sr->bottom() < mr.start())) {
286 // objArrays are always marked precisely, so limit processing
287 // with mr. Non-objArrays might be precisely marked, and since
288 // it's humongous it's worthwhile avoiding full processing.
289 // However, the card could be stale and only cover filler
290 // objects. That should be rare, so not worth checking for;
291 // instead let it fall out from the bounded iteration.
292 obj->oop_iterate(cl, mr);
293 return mr.end();
294 } else {
295 // If obj is not an objArray and mr contains the start of the
296 // obj, then this could be an imprecise mark, and we need to
297 // process the entire object.
298 int size = obj->oop_iterate_size(cl);
299 // We have scanned to the end of the object, but since there can be no objects
300 // after this humongous object in the region, we can return the end of the
301 // region if it is greater.
302 return MAX2((HeapWord*)obj + size, mr.end());
303 }
304 }
305
306 template <bool is_gc_active, class Closure>
307 HeapWord* HeapRegion::oops_on_memregion_seq_iterate_careful(MemRegion mr,
308 Closure* cl) {
309 assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
310 G1CollectedHeap* g1h = G1CollectedHeap::heap();
311
312 // Special handling for humongous regions.
313 if (is_humongous()) {
314 return do_oops_on_memregion_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
315 }
316 assert(is_old() || is_archive(), "Wrongly trying to iterate over region %u type %s", _hrm_index, get_type_str());
317
318 // Because mr has been trimmed to what's been allocated in this
319 // region, the parts of the heap that are examined here are always
320 // parsable; there's no need to use klass_or_null to detect
321 // in-progress allocation.
322
323 // Cache the boundaries of the memory region in some const locals
324 HeapWord* const start = mr.start();
325 HeapWord* const end = mr.end();
326
327 // Find the obj that extends onto mr.start().
328 // Update BOT as needed while finding start of (possibly dead)
329 // object containing the start of the region.
330 HeapWord* cur = block_start(start);
331
332 #ifdef ASSERT
333 {
334 assert(cur <= start,
335 "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
336 HeapWord* next = cur + block_size(cur);
337 assert(start < next,
338 "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
339 }
340 #endif
341
342 const G1CMBitMap* const bitmap = g1h->concurrent_mark()->prev_mark_bitmap();
343 while (true) {
344 oop obj = oop(cur);
345 assert(oopDesc::is_oop(obj, true), "Not an oop at " PTR_FORMAT, p2i(cur));
346 assert(obj->klass_or_null() != NULL,
347 "Unparsable heap at " PTR_FORMAT, p2i(cur));
348
349 size_t size;
350 bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);
351 bool is_precise = false;
352
353 cur += size;
354 if (!is_dead) {
355 // Process live object's references.
356
357 // Non-objArrays are usually marked imprecise at the object
358 // start, in which case we need to iterate over them in full.
359 // objArrays are precisely marked, but can still be iterated
360 // over in full if completely covered.
361 if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
362 obj->oop_iterate(cl);
363 } else {
364 obj->oop_iterate(cl, mr);
365 is_precise = true;
366 }
367 }
368 if (cur >= end) {
369 return is_precise ? end : cur;
370 }
371 }
372 }
373
374 inline int HeapRegion::age_in_surv_rate_group() const {
375 assert(has_surv_rate_group(), "pre-condition");
376 assert(has_valid_age_in_surv_rate(), "pre-condition");
377 return _surv_rate_group->age_in_group(_age_index);
378 }
379
380 inline bool HeapRegion::has_valid_age_in_surv_rate() const {
381 return SurvRateGroup::is_valid_age_index(_age_index);
382 }
383
384 inline bool HeapRegion::has_surv_rate_group() const {
385 return _surv_rate_group != NULL;
386 }
387
388 inline double HeapRegion::surv_rate_prediction(G1Predictions const& predictor) const {
389 assert(has_surv_rate_group(), "pre-condition");
390 return _surv_rate_group->surv_rate_pred(predictor, age_in_surv_rate_group());
391 }
392
393 inline void HeapRegion::install_surv_rate_group(SurvRateGroup* surv_rate_group) {
394 assert(surv_rate_group != NULL, "pre-condition");
395 assert(!has_surv_rate_group(), "pre-condition");
396 assert(is_young(), "pre-condition");
397
398 _surv_rate_group = surv_rate_group;
399 _age_index = surv_rate_group->next_age_index();
400 }
401
402 inline void HeapRegion::uninstall_surv_rate_group() {
403 if (has_surv_rate_group()) {
404 assert(has_valid_age_in_surv_rate(), "pre-condition");
405 assert(is_young(), "pre-condition");
406
407 _surv_rate_group = NULL;
408 _age_index = SurvRateGroup::InvalidAgeIndex;
409 } else {
410 assert(!has_valid_age_in_surv_rate(), "pre-condition");
411 }
412 }
413
414 inline void HeapRegion::record_surv_words_in_group(size_t words_survived) {
415 assert(has_surv_rate_group(), "pre-condition");
416 assert(has_valid_age_in_surv_rate(), "pre-condition");
417 int age_in_group = age_in_surv_rate_group();
418 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
419 }
420
421 #endif // SHARE_GC_G1_HEAPREGION_INLINE_HPP