1 /*
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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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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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13 * accompanied this code).
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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/heapRegion.hpp"
32 #include "gc/shared/space.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "runtime/atomic.hpp"
35 #include "runtime/prefetch.inline.hpp"
36 #include "utilities/align.hpp"
37
38 inline HeapWord* G1ContiguousSpace::allocate_impl(size_t min_word_size,
39 size_t desired_word_size,
40 size_t* actual_size) {
41 HeapWord* obj = top();
42 size_t available = pointer_delta(end(), obj);
43 size_t want_to_allocate = MIN2(available, desired_word_size);
44 if (want_to_allocate >= min_word_size) {
45 HeapWord* new_top = obj + want_to_allocate;
46 set_top(new_top);
47 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
48 *actual_size = want_to_allocate;
49 return obj;
50 } else {
51 return NULL;
52 }
53 }
54
55 inline HeapWord* G1ContiguousSpace::par_allocate_impl(size_t min_word_size,
56 size_t desired_word_size,
57 size_t* actual_size) {
58 do {
59 HeapWord* obj = top();
60 size_t available = pointer_delta(end(), obj);
61 size_t want_to_allocate = MIN2(available, desired_word_size);
62 if (want_to_allocate >= min_word_size) {
63 HeapWord* new_top = obj + want_to_allocate;
64 HeapWord* result = Atomic::cmpxchg(new_top, top_addr(), obj);
65 // result can be one of two:
66 // the old top value: the exchange succeeded
67 // otherwise: the new value of the top is returned.
68 if (result == obj) {
69 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
70 *actual_size = want_to_allocate;
71 return obj;
72 }
73 } else {
74 return NULL;
75 }
76 } while (true);
77 }
78
79 inline HeapWord* G1ContiguousSpace::allocate(size_t min_word_size,
80 size_t desired_word_size,
81 size_t* actual_size) {
82 HeapWord* res = allocate_impl(min_word_size, desired_word_size, actual_size);
83 if (res != NULL) {
84 _bot_part.alloc_block(res, *actual_size);
85 }
86 return res;
87 }
88
89 inline HeapWord* G1ContiguousSpace::allocate(size_t word_size) {
90 size_t temp;
91 return allocate(word_size, word_size, &temp);
92 }
93
94 inline HeapWord* G1ContiguousSpace::par_allocate(size_t word_size) {
95 size_t temp;
96 return par_allocate(word_size, word_size, &temp);
97 }
98
99 // Because of the requirement of keeping "_offsets" up to date with the
100 // allocations, we sequentialize these with a lock. Therefore, best if
101 // this is used for larger LAB allocations only.
102 inline HeapWord* G1ContiguousSpace::par_allocate(size_t min_word_size,
103 size_t desired_word_size,
104 size_t* actual_size) {
105 MutexLocker x(&_par_alloc_lock);
106 return allocate(min_word_size, desired_word_size, actual_size);
107 }
108
109 inline HeapWord* G1ContiguousSpace::block_start(const void* p) {
110 return _bot_part.block_start(p);
111 }
112
113 inline HeapWord*
114 G1ContiguousSpace::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
138 HeapRegion::block_is_obj(const HeapWord* p) const {
139 G1CollectedHeap* g1h = G1CollectedHeap::heap();
140
141 if (!this->is_in(p)) {
142 assert(is_continues_humongous(), "This case can only happen for humongous regions");
143 return (p == humongous_start_region()->bottom());
144 }
145 if (ClassUnloadingWithConcurrentMark) {
146 return !g1h->is_obj_dead(oop(p), this);
147 }
148 return p < top();
149 }
150
151 inline size_t HeapRegion::block_size_using_bitmap(const HeapWord* addr, const G1CMBitMap* const prev_bitmap) const {
152 assert(ClassUnloadingWithConcurrentMark,
153 "All blocks should be objects if class unloading isn't used, so this method should not be called. "
154 "HR: [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ") "
155 "addr: " PTR_FORMAT,
156 p2i(bottom()), p2i(top()), p2i(end()), p2i(addr));
157
158 // Old regions' dead objects may have dead classes
159 // We need to find the next live object using the bitmap
160 HeapWord* next = prev_bitmap->get_next_marked_addr(addr, prev_top_at_mark_start());
161
162 assert(next > addr, "must get the next live object");
163 return pointer_delta(next, addr);
164 }
165
166 inline bool HeapRegion::is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const {
167 assert(is_in_reserved(obj), "Object " PTR_FORMAT " must be in region", p2i(obj));
168 return !obj_allocated_since_prev_marking(obj) &&
169 !prev_bitmap->is_marked((HeapWord*)obj) &&
170 !is_open_archive();
171 }
172
173 inline size_t HeapRegion::block_size(const HeapWord *addr) const {
174 if (addr == top()) {
175 return pointer_delta(end(), addr);
176 }
177
178 if (block_is_obj(addr)) {
179 return oop(addr)->size();
180 }
181
182 return block_size_using_bitmap(addr, G1CollectedHeap::heap()->concurrent_mark()->prev_mark_bitmap());
183 }
184
185 inline void HeapRegion::complete_compaction() {
186 // Reset space and bot after compaction is complete if needed.
187 reset_after_compaction();
188 if (used_region().is_empty()) {
189 reset_bot();
190 }
191
192 // After a compaction the mark bitmap is invalid, so we must
193 // treat all objects as being inside the unmarked area.
194 zero_marked_bytes();
195 init_top_at_mark_start();
196
197 // Clear unused heap memory in debug builds.
198 if (ZapUnusedHeapArea) {
199 mangle_unused_area();
200 }
201 }
202
203 template<typename ApplyToMarkedClosure>
204 inline void HeapRegion::apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure) {
205 HeapWord* limit = scan_limit();
206 HeapWord* next_addr = bottom();
207
208 while (next_addr < limit) {
209 Prefetch::write(next_addr, PrefetchScanIntervalInBytes);
210 // This explicit is_marked check is a way to avoid
211 // some extra work done by get_next_marked_addr for
212 // the case where next_addr is marked.
213 if (bitmap->is_marked(next_addr)) {
214 oop current = oop(next_addr);
215 next_addr += closure->apply(current);
216 } else {
217 next_addr = bitmap->get_next_marked_addr(next_addr, limit);
218 }
219 }
220
221 assert(next_addr == limit, "Should stop the scan at the limit.");
222 }
223
224 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t min_word_size,
225 size_t desired_word_size,
226 size_t* actual_word_size) {
227 assert(is_young(), "we can only skip BOT updates on young regions");
228 return par_allocate_impl(min_word_size, desired_word_size, actual_word_size);
229 }
230
231 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
232 size_t temp;
233 return allocate_no_bot_updates(word_size, word_size, &temp);
234 }
235
236 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t min_word_size,
237 size_t desired_word_size,
238 size_t* actual_word_size) {
239 assert(is_young(), "we can only skip BOT updates on young regions");
240 return allocate_impl(min_word_size, desired_word_size, actual_word_size);
241 }
242
243 inline void HeapRegion::note_start_of_marking() {
244 _next_marked_bytes = 0;
245 _next_top_at_mark_start = top();
246 }
247
248 inline void HeapRegion::note_end_of_marking() {
249 _prev_top_at_mark_start = _next_top_at_mark_start;
250 _next_top_at_mark_start = bottom();
251 _prev_marked_bytes = _next_marked_bytes;
252 _next_marked_bytes = 0;
253 }
254
255 inline bool HeapRegion::in_collection_set() const {
256 return G1CollectedHeap::heap()->is_in_cset(this);
257 }
258
259 template <class Closure, bool is_gc_active>
260 HeapWord* HeapRegion::do_oops_on_memregion_in_humongous(MemRegion mr,
261 Closure* cl,
262 G1CollectedHeap* g1h) {
263 assert(is_humongous(), "precondition");
264 HeapRegion* sr = humongous_start_region();
265 oop obj = oop(sr->bottom());
266
267 // If concurrent and klass_or_null is NULL, then space has been
268 // allocated but the object has not yet been published by setting
269 // the klass. That can only happen if the card is stale. However,
270 // we've already set the card clean, so we must return failure,
271 // since the allocating thread could have performed a write to the
272 // card that might be missed otherwise.
273 if (!is_gc_active && (obj->klass_or_null_acquire() == NULL)) {
274 return NULL;
275 }
276
277 // We have a well-formed humongous object at the start of sr.
278 // Only filler objects follow a humongous object in the containing
279 // regions, and we can ignore those. So only process the one
280 // humongous object.
281 if (g1h->is_obj_dead(obj, sr)) {
282 // The object is dead. There can be no other object in this region, so return
283 // the end of that region.
284 return end();
285 }
286 if (obj->is_objArray() || (sr->bottom() < mr.start())) {
287 // objArrays are always marked precisely, so limit processing
288 // with mr. Non-objArrays might be precisely marked, and since
289 // it's humongous it's worthwhile avoiding full processing.
290 // However, the card could be stale and only cover filler
291 // objects. That should be rare, so not worth checking for;
292 // instead let it fall out from the bounded iteration.
293 obj->oop_iterate(cl, mr);
294 return mr.end();
295 } else {
296 // If obj is not an objArray and mr contains the start of the
297 // obj, then this could be an imprecise mark, and we need to
298 // process the entire object.
299 int size = obj->oop_iterate_size(cl);
300 // We have scanned to the end of the object, but since there can be no objects
301 // after this humongous object in the region, we can return the end of the
302 // region if it is greater.
303 return MAX2((HeapWord*)obj + size, mr.end());
304 }
305 }
306
307 template <bool is_gc_active, class Closure>
308 HeapWord* HeapRegion::oops_on_memregion_seq_iterate_careful(MemRegion mr,
309 Closure* cl) {
310 assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
311 G1CollectedHeap* g1h = G1CollectedHeap::heap();
312
313 // Special handling for humongous regions.
314 if (is_humongous()) {
315 return do_oops_on_memregion_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
316 }
317 assert(is_old() || is_archive(), "Wrongly trying to iterate over region %u type %s", _hrm_index, get_type_str());
318
319 // Because mr has been trimmed to what's been allocated in this
320 // region, the parts of the heap that are examined here are always
321 // parsable; there's no need to use klass_or_null to detect
322 // in-progress allocation.
323
324 // Cache the boundaries of the memory region in some const locals
325 HeapWord* const start = mr.start();
326 HeapWord* const end = mr.end();
327
328 // Find the obj that extends onto mr.start().
329 // Update BOT as needed while finding start of (possibly dead)
330 // object containing the start of the region.
331 HeapWord* cur = block_start(start);
332
333 #ifdef ASSERT
334 {
335 assert(cur <= start,
336 "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
337 HeapWord* next = cur + block_size(cur);
338 assert(start < next,
339 "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
340 }
341 #endif
342
343 const G1CMBitMap* const bitmap = g1h->concurrent_mark()->prev_mark_bitmap();
344 while (true) {
345 oop obj = oop(cur);
346 assert(oopDesc::is_oop(obj, true), "Not an oop at " PTR_FORMAT, p2i(cur));
347 assert(obj->klass_or_null() != NULL,
348 "Unparsable heap at " PTR_FORMAT, p2i(cur));
349
350 size_t size;
351 bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);
352 bool is_precise = false;
353
354 cur += size;
355 if (!is_dead) {
356 // Process live object's references.
357
358 // Non-objArrays are usually marked imprecise at the object
359 // start, in which case we need to iterate over them in full.
360 // objArrays are precisely marked, but can still be iterated
361 // over in full if completely covered.
362 if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
363 obj->oop_iterate(cl);
364 } else {
365 obj->oop_iterate(cl, mr);
366 is_precise = true;
367 }
368 }
369 if (cur >= end) {
370 return is_precise ? end : cur;
371 }
372 }
373 }
374
375 #endif // SHARE_GC_G1_HEAPREGION_INLINE_HPP