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src/hotspot/share/gc/shared/space.inline.hpp

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 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 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.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  *
 23  */
 24 
 25 #ifndef SHARE_GC_SHARED_SPACE_INLINE_HPP
 26 #define SHARE_GC_SHARED_SPACE_INLINE_HPP
 27 
 28 #include "gc/shared/space.hpp"
 29 
 30 #include "gc/shared/blockOffsetTable.inline.hpp"
 31 #include "gc/shared/collectedHeap.hpp"
 32 #include "gc/shared/generation.hpp"

 33 #include "gc/shared/spaceDecorator.hpp"
 34 #include "oops/oopsHierarchy.hpp"
 35 #include "oops/oop.inline.hpp"
 36 #include "runtime/prefetch.inline.hpp"
 37 #include "runtime/safepoint.hpp"
 38 #if INCLUDE_SERIALGC
 39 #include "gc/serial/markSweep.inline.hpp"
 40 #endif
 41 
 42 inline HeapWord* Space::block_start(const void* p) {
 43   return block_start_const(p);
 44 }
 45 
 46 inline HeapWord* OffsetTableContigSpace::allocate(size_t size) {
 47   HeapWord* res = ContiguousSpace::allocate(size);
 48   if (res != NULL) {
 49     _offsets.alloc_block(res, size);
 50   }
 51   return res;
 52 }

146     assert(cp->gen != NULL, "need a generation");
147     assert(cp->threshold == NULL, "just checking");
148     assert(cp->gen->first_compaction_space() == space, "just checking");
149     cp->space = cp->gen->first_compaction_space();
150     cp->threshold = cp->space->initialize_threshold();
151     cp->space->set_compaction_top(cp->space->bottom());
152   }
153 
154   HeapWord* compact_top = cp->space->compaction_top(); // This is where we are currently compacting to.
155 
156   DeadSpacer dead_spacer(space);
157 
158   HeapWord*  end_of_live = space->bottom();  // One byte beyond the last byte of the last live object.
159   HeapWord*  first_dead = NULL; // The first dead object.
160 
161   const intx interval = PrefetchScanIntervalInBytes;
162 
163   HeapWord* cur_obj = space->bottom();
164   HeapWord* scan_limit = space->scan_limit();
165 

166   while (cur_obj < scan_limit) {
167     if (space->scanned_block_is_obj(cur_obj) && cast_to_oop(cur_obj)->is_gc_marked()) {
168       // prefetch beyond cur_obj
169       Prefetch::write(cur_obj, interval);
170       size_t size = space->scanned_block_size(cur_obj);
171       compact_top = cp->space->forward(cast_to_oop(cur_obj), size, cp, compact_top);
172       cur_obj += size;
173       end_of_live = cur_obj;
174     } else {
175       // run over all the contiguous dead objects
176       HeapWord* end = cur_obj;
177       do {
178         // prefetch beyond end
179         Prefetch::write(end, interval);
180         end += space->scanned_block_size(end);
181       } while (end < scan_limit && (!space->scanned_block_is_obj(end) || !cast_to_oop(end)->is_gc_marked()));
182 
183       // see if we might want to pretend this object is alive so that
184       // we don't have to compact quite as often.
185       if (cur_obj == compact_top && dead_spacer.insert_deadspace(cur_obj, end)) {
186         oop obj = cast_to_oop(cur_obj);
187         compact_top = cp->space->forward(obj, obj->size(), cp, compact_top);
188         end_of_live = end;
189       } else {
190         // otherwise, it really is a free region.
191 
192         // cur_obj is a pointer to a dead object. Use this dead memory to store a pointer to the next live object.
193         *(HeapWord**)cur_obj = end;
194 
195         // see if this is the first dead region.
196         if (first_dead == NULL) {
197           first_dead = cur_obj;
198         }
199       }
200 
201       // move on to the next object
202       cur_obj = end;
203     }
204   }
205 
206   assert(cur_obj == scan_limit, "just checking");
207   space->_end_of_live = end_of_live;
208   if (first_dead != NULL) {
209     space->_first_dead = first_dead;
210   } else {
211     space->_first_dead = end_of_live;
212   }
213 
214   // save the compaction_top of the compaction space.
215   cp->space->set_compaction_top(compact_top);
216 }
217 
218 template <class SpaceType>
219 inline void CompactibleSpace::scan_and_adjust_pointers(SpaceType* space) {
220   // adjust all the interior pointers to point at the new locations of objects
221   // Used by MarkSweep::mark_sweep_phase3()
222 
223   HeapWord* cur_obj = space->bottom();
224   HeapWord* const end_of_live = space->_end_of_live;  // Established by "scan_and_forward".
225   HeapWord* const first_dead = space->_first_dead;    // Established by "scan_and_forward".

226 
227   assert(first_dead <= end_of_live, "Stands to reason, no?");
228 
229   const intx interval = PrefetchScanIntervalInBytes;
230 
231   debug_only(HeapWord* prev_obj = NULL);
232   while (cur_obj < end_of_live) {
233     Prefetch::write(cur_obj, interval);
234     if (cur_obj < first_dead || cast_to_oop(cur_obj)->is_gc_marked()) {
235       // cur_obj is alive
236       // point all the oops to the new location
237       size_t size = MarkSweep::adjust_pointers(cast_to_oop(cur_obj));
238       size = space->adjust_obj_size(size);
239       debug_only(prev_obj = cur_obj);
240       cur_obj += size;
241     } else {
242       debug_only(prev_obj = cur_obj);
243       // cur_obj is not a live object, instead it points at the next live object
244       cur_obj = *(HeapWord**)cur_obj;
245       assert(cur_obj > prev_obj, "we should be moving forward through memory, cur_obj: " PTR_FORMAT ", prev_obj: " PTR_FORMAT, p2i(cur_obj), p2i(prev_obj));
246     }
247   }
248 
249   assert(cur_obj == end_of_live, "just checking");
250 }
251 
252 #ifdef ASSERT
253 template <class SpaceType>
254 inline void CompactibleSpace::verify_up_to_first_dead(SpaceType* space) {
255   HeapWord* cur_obj = space->bottom();
256 
257   if (cur_obj < space->_end_of_live && space->_first_dead > cur_obj && !cast_to_oop(cur_obj)->is_gc_marked()) {

299   HeapWord* const end_of_live = space->_end_of_live;
300 
301   assert(space->_first_dead <= end_of_live, "Invariant. _first_dead: " PTR_FORMAT " <= end_of_live: " PTR_FORMAT, p2i(space->_first_dead), p2i(end_of_live));
302   if (space->_first_dead == end_of_live && (bottom == end_of_live || !cast_to_oop(bottom)->is_gc_marked())) {
303     // Nothing to compact. The space is either empty or all live object should be left in place.
304     clear_empty_region(space);
305     return;
306   }
307 
308   const intx scan_interval = PrefetchScanIntervalInBytes;
309   const intx copy_interval = PrefetchCopyIntervalInBytes;
310 
311   assert(bottom < end_of_live, "bottom: " PTR_FORMAT " should be < end_of_live: " PTR_FORMAT, p2i(bottom), p2i(end_of_live));
312   HeapWord* cur_obj = bottom;
313   if (space->_first_dead > cur_obj && !cast_to_oop(cur_obj)->is_gc_marked()) {
314     // All object before _first_dead can be skipped. They should not be moved.
315     // A pointer to the first live object is stored at the memory location for _first_dead.
316     cur_obj = *(HeapWord**)(space->_first_dead);
317   }
318 


319   debug_only(HeapWord* prev_obj = NULL);
320   while (cur_obj < end_of_live) {
321     if (!cast_to_oop(cur_obj)->is_gc_marked()) {
322       debug_only(prev_obj = cur_obj);
323       // The first word of the dead object contains a pointer to the next live object or end of space.
324       cur_obj = *(HeapWord**)cur_obj;
325       assert(cur_obj > prev_obj, "we should be moving forward through memory");
326     } else {
327       // prefetch beyond q
328       Prefetch::read(cur_obj, scan_interval);
329 
330       // size and destination
331       size_t size = space->obj_size(cur_obj);
332       HeapWord* compaction_top = cast_from_oop<HeapWord*>(cast_to_oop(cur_obj)->forwardee());
333 
334       // prefetch beyond compaction_top
335       Prefetch::write(compaction_top, copy_interval);
336 
337       // copy object and reinit its mark
338       assert(cur_obj != compaction_top, "everything in this pass should be moving");
339       Copy::aligned_conjoint_words(cur_obj, compaction_top, size);
340       cast_to_oop(compaction_top)->init_mark();
341       assert(cast_to_oop(compaction_top)->klass() != NULL, "should have a class");
342 
343       debug_only(prev_obj = cur_obj);
344       cur_obj += size;
345     }
346   }
347 
348   clear_empty_region(space);
349 }
350 
351 #endif // INCLUDE_SERIALGC
352 

 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 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.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
 21  * questions.
 22  *
 23  */
 24 
 25 #ifndef SHARE_GC_SHARED_SPACE_INLINE_HPP
 26 #define SHARE_GC_SHARED_SPACE_INLINE_HPP
 27 
 28 #include "gc/shared/space.hpp"
 29 
 30 #include "gc/shared/blockOffsetTable.inline.hpp"
 31 #include "gc/shared/collectedHeap.hpp"
 32 #include "gc/shared/generation.hpp"
 33 #include "gc/shared/genCollectedHeap.hpp"
 34 #include "gc/shared/spaceDecorator.hpp"
 35 #include "oops/oopsHierarchy.hpp"
 36 #include "oops/oop.inline.hpp"
 37 #include "runtime/prefetch.inline.hpp"
 38 #include "runtime/safepoint.hpp"
 39 #if INCLUDE_SERIALGC
 40 #include "gc/serial/markSweep.inline.hpp"
 41 #endif
 42 
 43 inline HeapWord* Space::block_start(const void* p) {
 44   return block_start_const(p);
 45 }
 46 
 47 inline HeapWord* OffsetTableContigSpace::allocate(size_t size) {
 48   HeapWord* res = ContiguousSpace::allocate(size);
 49   if (res != NULL) {
 50     _offsets.alloc_block(res, size);
 51   }
 52   return res;
 53 }

147     assert(cp->gen != NULL, "need a generation");
148     assert(cp->threshold == NULL, "just checking");
149     assert(cp->gen->first_compaction_space() == space, "just checking");
150     cp->space = cp->gen->first_compaction_space();
151     cp->threshold = cp->space->initialize_threshold();
152     cp->space->set_compaction_top(cp->space->bottom());
153   }
154 
155   HeapWord* compact_top = cp->space->compaction_top(); // This is where we are currently compacting to.
156 
157   DeadSpacer dead_spacer(space);
158 
159   HeapWord*  end_of_live = space->bottom();  // One byte beyond the last byte of the last live object.
160   HeapWord*  first_dead = NULL; // The first dead object.
161 
162   const intx interval = PrefetchScanIntervalInBytes;
163 
164   HeapWord* cur_obj = space->bottom();
165   HeapWord* scan_limit = space->scan_limit();
166 
167   SlidingForwarding* const forwarding = GenCollectedHeap::heap()->forwarding();
168   while (cur_obj < scan_limit) {
169     if (space->scanned_block_is_obj(cur_obj) && cast_to_oop(cur_obj)->is_gc_marked()) {
170       // prefetch beyond cur_obj
171       Prefetch::write(cur_obj, interval);
172       size_t size = space->scanned_block_size(cur_obj);
173       compact_top = cp->space->forward(cast_to_oop(cur_obj), size, cp, compact_top, forwarding);
174       cur_obj += size;
175       end_of_live = cur_obj;
176     } else {
177       // run over all the contiguous dead objects
178       HeapWord* end = cur_obj;
179       do {
180         // prefetch beyond end
181         Prefetch::write(end, interval);
182         end += space->scanned_block_size(end);
183       } while (end < scan_limit && (!space->scanned_block_is_obj(end) || !cast_to_oop(end)->is_gc_marked()));
184 
185       // see if we might want to pretend this object is alive so that
186       // we don't have to compact quite as often.
187       if (cur_obj == compact_top && dead_spacer.insert_deadspace(cur_obj, end)) {
188         oop obj = cast_to_oop(cur_obj);
189         compact_top = cp->space->forward(obj, obj->size(), cp, compact_top, forwarding);
190         end_of_live = end;
191       } else {
192         // otherwise, it really is a free region.
193 
194         // cur_obj is a pointer to a dead object. Use this dead memory to store a pointer to the next live object.
195         *(HeapWord**)cur_obj = end;
196 
197         // see if this is the first dead region.
198         if (first_dead == NULL) {
199           first_dead = cur_obj;
200         }
201       }
202 
203       // move on to the next object
204       cur_obj = end;
205     }
206   }
207 
208   assert(cur_obj == scan_limit, "just checking");
209   space->_end_of_live = end_of_live;
210   if (first_dead != NULL) {
211     space->_first_dead = first_dead;
212   } else {
213     space->_first_dead = end_of_live;
214   }
215 
216   // save the compaction_top of the compaction space.
217   cp->space->set_compaction_top(compact_top);
218 }
219 
220 template <class SpaceType>
221 inline void CompactibleSpace::scan_and_adjust_pointers(SpaceType* space) {
222   // adjust all the interior pointers to point at the new locations of objects
223   // Used by MarkSweep::mark_sweep_phase3()
224 
225   HeapWord* cur_obj = space->bottom();
226   HeapWord* const end_of_live = space->_end_of_live;  // Established by "scan_and_forward".
227   HeapWord* const first_dead = space->_first_dead;    // Established by "scan_and_forward".
228   const SlidingForwarding* const forwarding = GenCollectedHeap::heap()->forwarding();
229 
230   assert(first_dead <= end_of_live, "Stands to reason, no?");
231 
232   const intx interval = PrefetchScanIntervalInBytes;
233 
234   debug_only(HeapWord* prev_obj = NULL);
235   while (cur_obj < end_of_live) {
236     Prefetch::write(cur_obj, interval);
237     if (cur_obj < first_dead || cast_to_oop(cur_obj)->is_gc_marked()) {
238       // cur_obj is alive
239       // point all the oops to the new location
240       size_t size = MarkSweep::adjust_pointers(forwarding, cast_to_oop(cur_obj));
241       size = space->adjust_obj_size(size);
242       debug_only(prev_obj = cur_obj);
243       cur_obj += size;
244     } else {
245       debug_only(prev_obj = cur_obj);
246       // cur_obj is not a live object, instead it points at the next live object
247       cur_obj = *(HeapWord**)cur_obj;
248       assert(cur_obj > prev_obj, "we should be moving forward through memory, cur_obj: " PTR_FORMAT ", prev_obj: " PTR_FORMAT, p2i(cur_obj), p2i(prev_obj));
249     }
250   }
251 
252   assert(cur_obj == end_of_live, "just checking");
253 }
254 
255 #ifdef ASSERT
256 template <class SpaceType>
257 inline void CompactibleSpace::verify_up_to_first_dead(SpaceType* space) {
258   HeapWord* cur_obj = space->bottom();
259 
260   if (cur_obj < space->_end_of_live && space->_first_dead > cur_obj && !cast_to_oop(cur_obj)->is_gc_marked()) {

302   HeapWord* const end_of_live = space->_end_of_live;
303 
304   assert(space->_first_dead <= end_of_live, "Invariant. _first_dead: " PTR_FORMAT " <= end_of_live: " PTR_FORMAT, p2i(space->_first_dead), p2i(end_of_live));
305   if (space->_first_dead == end_of_live && (bottom == end_of_live || !cast_to_oop(bottom)->is_gc_marked())) {
306     // Nothing to compact. The space is either empty or all live object should be left in place.
307     clear_empty_region(space);
308     return;
309   }
310 
311   const intx scan_interval = PrefetchScanIntervalInBytes;
312   const intx copy_interval = PrefetchCopyIntervalInBytes;
313 
314   assert(bottom < end_of_live, "bottom: " PTR_FORMAT " should be < end_of_live: " PTR_FORMAT, p2i(bottom), p2i(end_of_live));
315   HeapWord* cur_obj = bottom;
316   if (space->_first_dead > cur_obj && !cast_to_oop(cur_obj)->is_gc_marked()) {
317     // All object before _first_dead can be skipped. They should not be moved.
318     // A pointer to the first live object is stored at the memory location for _first_dead.
319     cur_obj = *(HeapWord**)(space->_first_dead);
320   }
321 
322   const SlidingForwarding* const forwarding = GenCollectedHeap::heap()->forwarding();
323 
324   debug_only(HeapWord* prev_obj = NULL);
325   while (cur_obj < end_of_live) {
326     if (!cast_to_oop(cur_obj)->is_gc_marked()) {
327       debug_only(prev_obj = cur_obj);
328       // The first word of the dead object contains a pointer to the next live object or end of space.
329       cur_obj = *(HeapWord**)cur_obj;
330       assert(cur_obj > prev_obj, "we should be moving forward through memory");
331     } else {
332       // prefetch beyond q
333       Prefetch::read(cur_obj, scan_interval);
334 
335       // size and destination
336       size_t size = space->obj_size(cur_obj);
337       HeapWord* compaction_top = cast_from_oop<HeapWord*>(forwarding->forwardee(cast_to_oop(cur_obj)));
338 
339       // prefetch beyond compaction_top
340       Prefetch::write(compaction_top, copy_interval);
341 
342       // copy object and reinit its mark
343       assert(cur_obj != compaction_top, "everything in this pass should be moving");
344       Copy::aligned_conjoint_words(cur_obj, compaction_top, size);
345       cast_to_oop(compaction_top)->init_mark();
346       assert(cast_to_oop(compaction_top)->klass() != NULL, "should have a class");
347 
348       debug_only(prev_obj = cur_obj);
349       cur_obj += size;
350     }
351   }
352 
353   clear_empty_region(space);
354 }
355 
356 #endif // INCLUDE_SERIALGC
357 
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