1 /*
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  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
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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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 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 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(&_top, obj, new_top);
 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 = cast_from_oop<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(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(cast_from_oop<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() || (cast_from_oop<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 G1SurvRateGroup::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(G1SurvRateGroup* 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 = G1SurvRateGroup::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