39 // can be collected independently.
40
41 // NOTE: Although a HeapRegion is a Space, its
42 // Space::initDirtyCardClosure method must not be called.
43 // The problem is that the existence of this method breaks
44 // the independence of barrier sets from remembered sets.
45 // The solution is to remove this method from the definition
46 // of a Space.
47
48 // Each heap region is self contained. top() and end() can never
49 // be set beyond the end of the region. For humongous objects,
50 // the first region is a StartsHumongous region. If the humongous
51 // object is larger than a heap region, the following regions will
52 // be of type ContinuesHumongous. In this case the top() of the
53 // StartHumongous region and all ContinuesHumongous regions except
54 // the last will point to their own end. The last ContinuesHumongous
55 // region may have top() equal the end of object if there isn't
56 // room for filler objects to pad out to the end of the region.
57
58 class G1CollectedHeap;
59 class G1CMBitMapRO;
60 class HeapRegionRemSet;
61 class HeapRegionRemSetIterator;
62 class HeapRegion;
63 class HeapRegionSetBase;
64 class nmethod;
65
66 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
67 #define HR_FORMAT_PARAMS(_hr_) \
68 (_hr_)->hrm_index(), \
69 (_hr_)->get_short_type_str(), \
70 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
71
72 // sentinel value for hrm_index
73 #define G1_NO_HRM_INDEX ((uint) -1)
74
75 // The complicating factor is that BlockOffsetTable diverged
76 // significantly, and we need functionality that is only in the G1 version.
77 // So I copied that code, which led to an alternate G1 version of
78 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
79 // be reconciled, then G1OffsetTableContigSpace could go away.
208 // See comments for CompactibleSpace for more information.
209 inline HeapWord* scan_limit() const {
210 return top();
211 }
212
213 inline bool scanned_block_is_obj(const HeapWord* addr) const {
214 return true; // Always true, since scan_limit is top
215 }
216
217 inline size_t scanned_block_size(const HeapWord* addr) const {
218 return HeapRegion::block_size(addr); // Avoid virtual call
219 }
220
221 void report_region_type_change(G1HeapRegionTraceType::Type to);
222
223 // Returns whether the given object address refers to a dead object, and either the
224 // size of the object (if live) or the size of the block (if dead) in size.
225 // May
226 // - only called with obj < top()
227 // - not called on humongous objects or archive regions
228 inline bool is_obj_dead_with_size(const oop obj, G1CMBitMapRO* prev_bitmap, size_t* size) const;
229
230 protected:
231 // The index of this region in the heap region sequence.
232 uint _hrm_index;
233
234 AllocationContext_t _allocation_context;
235
236 HeapRegionType _type;
237
238 // For a humongous region, region in which it starts.
239 HeapRegion* _humongous_start_region;
240
241 // True iff an attempt to evacuate an object in the region failed.
242 bool _evacuation_failed;
243
244 // Fields used by the HeapRegionSetBase class and subclasses.
245 HeapRegion* _next;
246 HeapRegion* _prev;
247 #ifdef ASSERT
248 HeapRegionSetBase* _containing_set;
284
285 // The RSet length that was added to the total value
286 // for the collection set.
287 size_t _recorded_rs_length;
288
289 // The predicted elapsed time that was added to total value
290 // for the collection set.
291 double _predicted_elapsed_time_ms;
292
293 // Iterate over the references in a humongous objects and apply the given closure
294 // to them.
295 // Humongous objects are allocated directly in the old-gen. So we need special
296 // handling for concurrent processing encountering an in-progress allocation.
297 template <class Closure, bool is_gc_active>
298 inline bool do_oops_on_card_in_humongous(MemRegion mr,
299 Closure* cl,
300 G1CollectedHeap* g1h);
301
302 // Returns the block size of the given (dead, potentially having its class unloaded) object
303 // starting at p extending to at most the prev TAMS using the given mark bitmap.
304 inline size_t block_size_using_bitmap(const HeapWord* p, const G1CMBitMapRO* prev_bitmap) const;
305 public:
306 HeapRegion(uint hrm_index,
307 G1BlockOffsetTable* bot,
308 MemRegion mr);
309
310 // Initializing the HeapRegion not only resets the data structure, but also
311 // resets the BOT for that heap region.
312 // The default values for clear_space means that we will do the clearing if
313 // there's clearing to be done ourselves. We also always mangle the space.
314 virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
315
316 static int LogOfHRGrainBytes;
317 static int LogOfHRGrainWords;
318
319 static size_t GrainBytes;
320 static size_t GrainWords;
321 static size_t CardsPerRegion;
322
323 static size_t align_up_to_region_byte_size(size_t sz) {
324 return (sz + (size_t) GrainBytes - 1) &
332 assert(p != NULL, "p can't be NULL");
333 assert(obj != NULL, "obj can't be NULL");
334 return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0;
335 }
336
337 static size_t max_region_size();
338 static size_t min_region_size_in_words();
339
340 // It sets up the heap region size (GrainBytes / GrainWords), as
341 // well as other related fields that are based on the heap region
342 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
343 // CardsPerRegion). All those fields are considered constant
344 // throughout the JVM's execution, therefore they should only be set
345 // up once during initialization time.
346 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
347
348 // All allocated blocks are occupied by objects in a HeapRegion
349 bool block_is_obj(const HeapWord* p) const;
350
351 // Returns whether the given object is dead based on TAMS and bitmap.
352 bool is_obj_dead(const oop obj, const G1CMBitMapRO* prev_bitmap) const;
353
354 // Returns the object size for all valid block starts
355 // and the amount of unallocated words if called on top()
356 size_t block_size(const HeapWord* p) const;
357
358 // Override for scan_and_forward support.
359 void prepare_for_compaction(CompactPoint* cp);
360
361 inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
362 inline HeapWord* allocate_no_bot_updates(size_t word_size);
363 inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
364
365 // If this region is a member of a HeapRegionManager, the index in that
366 // sequence, otherwise -1.
367 uint hrm_index() const { return _hrm_index; }
368
369 // The number of bytes marked live in the region in the last marking phase.
370 size_t marked_bytes() { return _prev_marked_bytes; }
371 size_t live_bytes() {
372 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
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39 // can be collected independently.
40
41 // NOTE: Although a HeapRegion is a Space, its
42 // Space::initDirtyCardClosure method must not be called.
43 // The problem is that the existence of this method breaks
44 // the independence of barrier sets from remembered sets.
45 // The solution is to remove this method from the definition
46 // of a Space.
47
48 // Each heap region is self contained. top() and end() can never
49 // be set beyond the end of the region. For humongous objects,
50 // the first region is a StartsHumongous region. If the humongous
51 // object is larger than a heap region, the following regions will
52 // be of type ContinuesHumongous. In this case the top() of the
53 // StartHumongous region and all ContinuesHumongous regions except
54 // the last will point to their own end. The last ContinuesHumongous
55 // region may have top() equal the end of object if there isn't
56 // room for filler objects to pad out to the end of the region.
57
58 class G1CollectedHeap;
59 class G1CMBitMap;
60 class HeapRegionRemSet;
61 class HeapRegionRemSetIterator;
62 class HeapRegion;
63 class HeapRegionSetBase;
64 class nmethod;
65
66 #define HR_FORMAT "%u:(%s)[" PTR_FORMAT "," PTR_FORMAT "," PTR_FORMAT "]"
67 #define HR_FORMAT_PARAMS(_hr_) \
68 (_hr_)->hrm_index(), \
69 (_hr_)->get_short_type_str(), \
70 p2i((_hr_)->bottom()), p2i((_hr_)->top()), p2i((_hr_)->end())
71
72 // sentinel value for hrm_index
73 #define G1_NO_HRM_INDEX ((uint) -1)
74
75 // The complicating factor is that BlockOffsetTable diverged
76 // significantly, and we need functionality that is only in the G1 version.
77 // So I copied that code, which led to an alternate G1 version of
78 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
79 // be reconciled, then G1OffsetTableContigSpace could go away.
208 // See comments for CompactibleSpace for more information.
209 inline HeapWord* scan_limit() const {
210 return top();
211 }
212
213 inline bool scanned_block_is_obj(const HeapWord* addr) const {
214 return true; // Always true, since scan_limit is top
215 }
216
217 inline size_t scanned_block_size(const HeapWord* addr) const {
218 return HeapRegion::block_size(addr); // Avoid virtual call
219 }
220
221 void report_region_type_change(G1HeapRegionTraceType::Type to);
222
223 // Returns whether the given object address refers to a dead object, and either the
224 // size of the object (if live) or the size of the block (if dead) in size.
225 // May
226 // - only called with obj < top()
227 // - not called on humongous objects or archive regions
228 inline bool is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const;
229
230 protected:
231 // The index of this region in the heap region sequence.
232 uint _hrm_index;
233
234 AllocationContext_t _allocation_context;
235
236 HeapRegionType _type;
237
238 // For a humongous region, region in which it starts.
239 HeapRegion* _humongous_start_region;
240
241 // True iff an attempt to evacuate an object in the region failed.
242 bool _evacuation_failed;
243
244 // Fields used by the HeapRegionSetBase class and subclasses.
245 HeapRegion* _next;
246 HeapRegion* _prev;
247 #ifdef ASSERT
248 HeapRegionSetBase* _containing_set;
284
285 // The RSet length that was added to the total value
286 // for the collection set.
287 size_t _recorded_rs_length;
288
289 // The predicted elapsed time that was added to total value
290 // for the collection set.
291 double _predicted_elapsed_time_ms;
292
293 // Iterate over the references in a humongous objects and apply the given closure
294 // to them.
295 // Humongous objects are allocated directly in the old-gen. So we need special
296 // handling for concurrent processing encountering an in-progress allocation.
297 template <class Closure, bool is_gc_active>
298 inline bool do_oops_on_card_in_humongous(MemRegion mr,
299 Closure* cl,
300 G1CollectedHeap* g1h);
301
302 // Returns the block size of the given (dead, potentially having its class unloaded) object
303 // starting at p extending to at most the prev TAMS using the given mark bitmap.
304 inline size_t block_size_using_bitmap(const HeapWord* p, const G1CMBitMap* const prev_bitmap) const;
305 public:
306 HeapRegion(uint hrm_index,
307 G1BlockOffsetTable* bot,
308 MemRegion mr);
309
310 // Initializing the HeapRegion not only resets the data structure, but also
311 // resets the BOT for that heap region.
312 // The default values for clear_space means that we will do the clearing if
313 // there's clearing to be done ourselves. We also always mangle the space.
314 virtual void initialize(MemRegion mr, bool clear_space = false, bool mangle_space = SpaceDecorator::Mangle);
315
316 static int LogOfHRGrainBytes;
317 static int LogOfHRGrainWords;
318
319 static size_t GrainBytes;
320 static size_t GrainWords;
321 static size_t CardsPerRegion;
322
323 static size_t align_up_to_region_byte_size(size_t sz) {
324 return (sz + (size_t) GrainBytes - 1) &
332 assert(p != NULL, "p can't be NULL");
333 assert(obj != NULL, "obj can't be NULL");
334 return (((uintptr_t) p ^ cast_from_oop<uintptr_t>(obj)) >> LogOfHRGrainBytes) == 0;
335 }
336
337 static size_t max_region_size();
338 static size_t min_region_size_in_words();
339
340 // It sets up the heap region size (GrainBytes / GrainWords), as
341 // well as other related fields that are based on the heap region
342 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
343 // CardsPerRegion). All those fields are considered constant
344 // throughout the JVM's execution, therefore they should only be set
345 // up once during initialization time.
346 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
347
348 // All allocated blocks are occupied by objects in a HeapRegion
349 bool block_is_obj(const HeapWord* p) const;
350
351 // Returns whether the given object is dead based on TAMS and bitmap.
352 bool is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const;
353
354 // Returns the object size for all valid block starts
355 // and the amount of unallocated words if called on top()
356 size_t block_size(const HeapWord* p) const;
357
358 // Override for scan_and_forward support.
359 void prepare_for_compaction(CompactPoint* cp);
360
361 inline HeapWord* par_allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* word_size);
362 inline HeapWord* allocate_no_bot_updates(size_t word_size);
363 inline HeapWord* allocate_no_bot_updates(size_t min_word_size, size_t desired_word_size, size_t* actual_size);
364
365 // If this region is a member of a HeapRegionManager, the index in that
366 // sequence, otherwise -1.
367 uint hrm_index() const { return _hrm_index; }
368
369 // The number of bytes marked live in the region in the last marking phase.
370 size_t marked_bytes() { return _prev_marked_bytes; }
371 size_t live_bytes() {
372 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
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