1 /*
2 * Copyright (c) 2001, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
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).
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.
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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
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23 */
24
25 #ifndef SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP
26 #define SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP
27
28 #include "gc/g1/g1BlockOffsetTable.inline.hpp"
29 #include "gc/g1/g1CollectedHeap.inline.hpp"
30 #include "gc/g1/heapRegion.hpp"
31 #include "gc/shared/space.hpp"
32 #include "oops/oop.inline.hpp"
33 #include "runtime/atomic.hpp"
34
35 inline HeapWord* G1ContiguousSpace::allocate_impl(size_t min_word_size,
36 size_t desired_word_size,
37 size_t* actual_size) {
38 HeapWord* obj = top();
39 size_t available = pointer_delta(end(), obj);
40 size_t want_to_allocate = MIN2(available, desired_word_size);
41 if (want_to_allocate >= min_word_size) {
42 HeapWord* new_top = obj + want_to_allocate;
43 set_top(new_top);
44 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
45 *actual_size = want_to_allocate;
46 return obj;
47 } else {
48 return NULL;
49 }
50 }
51
52 inline HeapWord* G1ContiguousSpace::par_allocate_impl(size_t min_word_size,
53 size_t desired_word_size,
54 size_t* actual_size) {
55 do {
56 HeapWord* obj = top();
57 size_t available = pointer_delta(end(), obj);
58 size_t want_to_allocate = MIN2(available, desired_word_size);
59 if (want_to_allocate >= min_word_size) {
60 HeapWord* new_top = obj + want_to_allocate;
61 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
62 // result can be one of two:
63 // the old top value: the exchange succeeded
64 // otherwise: the new value of the top is returned.
65 if (result == obj) {
66 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
67 *actual_size = want_to_allocate;
68 return obj;
69 }
70 } else {
71 return NULL;
72 }
73 } while (true);
74 }
75
76 inline HeapWord* G1ContiguousSpace::allocate(size_t min_word_size,
77 size_t desired_word_size,
78 size_t* actual_size) {
79 HeapWord* res = allocate_impl(min_word_size, desired_word_size, actual_size);
80 if (res != NULL) {
81 _bot_part.alloc_block(res, *actual_size);
82 }
83 return res;
84 }
85
86 inline HeapWord* G1ContiguousSpace::allocate(size_t word_size) {
87 size_t temp;
88 return allocate(word_size, word_size, &temp);
89 }
90
91 inline HeapWord* G1ContiguousSpace::par_allocate(size_t word_size) {
92 size_t temp;
93 return par_allocate(word_size, word_size, &temp);
94 }
95
96 // Because of the requirement of keeping "_offsets" up to date with the
97 // allocations, we sequentialize these with a lock. Therefore, best if
98 // this is used for larger LAB allocations only.
99 inline HeapWord* G1ContiguousSpace::par_allocate(size_t min_word_size,
100 size_t desired_word_size,
101 size_t* actual_size) {
102 MutexLocker x(&_par_alloc_lock);
103 return allocate(min_word_size, desired_word_size, actual_size);
104 }
105
106 inline HeapWord* G1ContiguousSpace::block_start(const void* p) {
107 return _bot_part.block_start(p);
108 }
109
110 inline HeapWord*
111 G1ContiguousSpace::block_start_const(const void* p) const {
112 return _bot_part.block_start_const(p);
113 }
114
115 inline bool HeapRegion::is_obj_dead_with_size(const oop obj, G1CMBitMapRO* prev_bitmap, size_t* size) const {
116 HeapWord* addr = (HeapWord*) obj;
117
118 assert(addr < top(), "must be");
119 assert(!is_archive(), "Archive regions should not have references into interesting regions.");
120 assert(!is_humongous(), "Humongous objects not handled here");
121 bool obj_is_dead = is_obj_dead(obj, prev_bitmap);
122
123 if (ClassUnloadingWithConcurrentMark && obj_is_dead) {
124 assert(!block_is_obj(addr), "must be");
125 *size = block_size_using_bitmap(addr, prev_bitmap);
126 } else {
127 assert(block_is_obj(addr), "must be");
128 *size = obj->size();
129 }
130 return obj_is_dead;
131 }
132
133 inline bool
134 HeapRegion::block_is_obj(const HeapWord* p) const {
135 G1CollectedHeap* g1h = G1CollectedHeap::heap();
136
137 if (!this->is_in(p)) {
138 assert(is_continues_humongous(), "This case can only happen for humongous regions");
139 return (p == humongous_start_region()->bottom());
140 }
141 if (ClassUnloadingWithConcurrentMark) {
142 return !g1h->is_obj_dead(oop(p), this);
143 }
144 return p < top();
145 }
146
147 inline size_t HeapRegion::block_size_using_bitmap(const HeapWord* addr, const G1CMBitMapRO* prev_bitmap) const {
148 assert(ClassUnloadingWithConcurrentMark,
149 "All blocks should be objects if class unloading isn't used, so this method should not be called. "
150 "HR: [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ") "
151 "addr: " PTR_FORMAT,
152 p2i(bottom()), p2i(top()), p2i(end()), p2i(addr));
153
154 // Old regions' dead objects may have dead classes
155 // We need to find the next live object using the bitmap
156 HeapWord* next = prev_bitmap->getNextMarkedWordAddress(addr, prev_top_at_mark_start());
157
158 assert(next > addr, "must get the next live object");
159 return pointer_delta(next, addr);
160 }
161
162 inline bool HeapRegion::is_obj_dead(const oop obj, const G1CMBitMapRO* prev_bitmap) const {
163 assert(is_in_reserved(obj), "Object " PTR_FORMAT " must be in region", p2i(obj));
164 return !obj_allocated_since_prev_marking(obj) && !prev_bitmap->isMarked((HeapWord*)obj);
165 }
166
167 inline size_t HeapRegion::block_size(const HeapWord *addr) const {
168 if (addr == top()) {
169 return pointer_delta(end(), addr);
170 }
171
172 if (block_is_obj(addr)) {
173 return oop(addr)->size();
174 }
175
176 return block_size_using_bitmap(addr, G1CollectedHeap::heap()->concurrent_mark()->prevMarkBitMap());
177 }
178
179 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t min_word_size,
180 size_t desired_word_size,
181 size_t* actual_word_size) {
182 assert(is_young(), "we can only skip BOT updates on young regions");
183 return par_allocate_impl(min_word_size, desired_word_size, actual_word_size);
184 }
185
186 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
187 size_t temp;
188 return allocate_no_bot_updates(word_size, word_size, &temp);
189 }
190
191 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t min_word_size,
192 size_t desired_word_size,
193 size_t* actual_word_size) {
194 assert(is_young(), "we can only skip BOT updates on young regions");
195 return allocate_impl(min_word_size, desired_word_size, actual_word_size);
196 }
197
198 inline void HeapRegion::note_start_of_marking() {
199 _next_marked_bytes = 0;
200 _next_top_at_mark_start = top();
201 }
202
203 inline void HeapRegion::note_end_of_marking() {
204 _prev_top_at_mark_start = _next_top_at_mark_start;
205 _prev_marked_bytes = _next_marked_bytes;
206 _next_marked_bytes = 0;
207 }
208
209 inline void HeapRegion::note_start_of_copying(bool during_initial_mark) {
210 if (is_survivor()) {
211 // This is how we always allocate survivors.
212 assert(_next_top_at_mark_start == bottom(), "invariant");
213 } else {
214 if (during_initial_mark) {
215 // During initial-mark we'll explicitly mark any objects on old
216 // regions that are pointed to by roots. Given that explicit
217 // marks only make sense under NTAMS it'd be nice if we could
218 // check that condition if we wanted to. Given that we don't
219 // know where the top of this region will end up, we simply set
220 // NTAMS to the end of the region so all marks will be below
221 // NTAMS. We'll set it to the actual top when we retire this region.
222 _next_top_at_mark_start = end();
223 } else {
224 // We could have re-used this old region as to-space over a
225 // couple of GCs since the start of the concurrent marking
226 // cycle. This means that [bottom,NTAMS) will contain objects
227 // copied up to and including initial-mark and [NTAMS, top)
228 // will contain objects copied during the concurrent marking cycle.
229 assert(top() >= _next_top_at_mark_start, "invariant");
230 }
231 }
232 }
233
234 inline void HeapRegion::note_end_of_copying(bool during_initial_mark) {
235 if (is_survivor()) {
236 // This is how we always allocate survivors.
237 assert(_next_top_at_mark_start == bottom(), "invariant");
238 } else {
239 if (during_initial_mark) {
240 // See the comment for note_start_of_copying() for the details
241 // on this.
242 assert(_next_top_at_mark_start == end(), "pre-condition");
243 _next_top_at_mark_start = top();
244 } else {
245 // See the comment for note_start_of_copying() for the details
246 // on this.
247 assert(top() >= _next_top_at_mark_start, "invariant");
248 }
249 }
250 }
251
252 inline bool HeapRegion::in_collection_set() const {
253 return G1CollectedHeap::heap()->is_in_cset(this);
254 }
255
256 template <class Closure, bool is_gc_active>
257 bool HeapRegion::do_oops_on_card_in_humongous(MemRegion mr,
258 Closure* cl,
259 G1CollectedHeap* g1h) {
260 assert(is_humongous(), "precondition");
261 HeapRegion* sr = humongous_start_region();
262 oop obj = oop(sr->bottom());
263
264 // If concurrent and klass_or_null is NULL, then space has been
265 // allocated but the object has not yet been published by setting
266 // the klass. That can only happen if the card is stale. However,
267 // we've already set the card clean, so we must return failure,
268 // since the allocating thread could have performed a write to the
269 // card that might be missed otherwise.
270 if (!is_gc_active && (obj->klass_or_null_acquire() == NULL)) {
271 return false;
272 }
273
274 // We have a well-formed humongous object at the start of sr.
275 // Only filler objects follow a humongous object in the containing
276 // regions, and we can ignore those. So only process the one
277 // humongous object.
278 if (!g1h->is_obj_dead(obj, sr)) {
279 if (obj->is_objArray() || (sr->bottom() < mr.start())) {
280 // objArrays are always marked precisely, so limit processing
281 // with mr. Non-objArrays might be precisely marked, and since
282 // it's humongous it's worthwhile avoiding full processing.
283 // However, the card could be stale and only cover filler
284 // objects. That should be rare, so not worth checking for;
285 // instead let it fall out from the bounded iteration.
286 obj->oop_iterate(cl, mr);
287 } else {
288 // If obj is not an objArray and mr contains the start of the
289 // obj, then this could be an imprecise mark, and we need to
290 // process the entire object.
291 obj->oop_iterate(cl);
292 }
293 }
294 return true;
295 }
296
297 template <bool is_gc_active, class Closure>
298 bool HeapRegion::oops_on_card_seq_iterate_careful(MemRegion mr,
299 Closure* cl) {
300 assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
301 G1CollectedHeap* g1h = G1CollectedHeap::heap();
302
303 // Special handling for humongous regions.
304 if (is_humongous()) {
305 return do_oops_on_card_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
306 }
307 assert(is_old(), "precondition");
308
309 // Because mr has been trimmed to what's been allocated in this
310 // region, the parts of the heap that are examined here are always
311 // parsable; there's no need to use klass_or_null to detect
312 // in-progress allocation.
313
314 // Cache the boundaries of the memory region in some const locals
315 HeapWord* const start = mr.start();
316 HeapWord* const end = mr.end();
317
318 // Find the obj that extends onto mr.start().
319 // Update BOT as needed while finding start of (possibly dead)
320 // object containing the start of the region.
321 HeapWord* cur = block_start(start);
322
323 #ifdef ASSERT
324 {
325 assert(cur <= start,
326 "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
327 HeapWord* next = cur + block_size(cur);
328 assert(start < next,
329 "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
330 }
331 #endif
332
333 G1CMBitMapRO* bitmap = g1h->concurrent_mark()->prevMarkBitMap();
334 do {
335 oop obj = oop(cur);
336 assert(obj->is_oop(true), "Not an oop at " PTR_FORMAT, p2i(cur));
337 assert(obj->klass_or_null() != NULL,
338 "Unparsable heap at " PTR_FORMAT, p2i(cur));
339
340 size_t size;
341 bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);
342
343 cur += size;
344 if (!is_dead) {
345 // Process live object's references.
346
347 // Non-objArrays are usually marked imprecise at the object
348 // start, in which case we need to iterate over them in full.
349 // objArrays are precisely marked, but can still be iterated
350 // over in full if completely covered.
351 if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
352 obj->oop_iterate(cl);
353 } else {
354 obj->oop_iterate(cl, mr);
355 }
356 }
357 } while (cur < end);
358
359 return true;
360 }
361
362 #endif // SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP