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 #include "utilities/align.hpp"
35
36 inline HeapWord* G1ContiguousSpace::allocate_impl(size_t min_word_size,
37 size_t desired_word_size,
38 size_t* actual_size) {
39 HeapWord* obj = top();
40 size_t available = pointer_delta(end(), obj);
41 size_t want_to_allocate = MIN2(available, desired_word_size);
42 if (want_to_allocate >= min_word_size) {
43 HeapWord* new_top = obj + want_to_allocate;
44 set_top(new_top);
45 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
46 *actual_size = want_to_allocate;
47 return obj;
48 } else {
49 return NULL;
50 }
51 }
52
53 inline HeapWord* G1ContiguousSpace::par_allocate_impl(size_t min_word_size,
54 size_t desired_word_size,
55 size_t* actual_size) {
56 do {
57 HeapWord* obj = top();
58 size_t available = pointer_delta(end(), obj);
59 size_t want_to_allocate = MIN2(available, desired_word_size);
60 if (want_to_allocate >= min_word_size) {
61 HeapWord* new_top = obj + want_to_allocate;
62 HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
63 // result can be one of two:
64 // the old top value: the exchange succeeded
65 // otherwise: the new value of the top is returned.
66 if (result == obj) {
67 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
68 *actual_size = want_to_allocate;
69 return obj;
70 }
71 } else {
72 return NULL;
73 }
74 } while (true);
75 }
76
77 inline HeapWord* G1ContiguousSpace::allocate(size_t min_word_size,
78 size_t desired_word_size,
79 size_t* actual_size) {
80 HeapWord* res = allocate_impl(min_word_size, desired_word_size, actual_size);
81 if (res != NULL) {
82 _bot_part.alloc_block(res, *actual_size);
83 }
84 return res;
85 }
86
87 inline HeapWord* G1ContiguousSpace::allocate(size_t word_size) {
88 size_t temp;
89 return allocate(word_size, word_size, &temp);
90 }
91
92 inline HeapWord* G1ContiguousSpace::par_allocate(size_t word_size) {
93 size_t temp;
94 return par_allocate(word_size, word_size, &temp);
95 }
96
97 // Because of the requirement of keeping "_offsets" up to date with the
98 // allocations, we sequentialize these with a lock. Therefore, best if
99 // this is used for larger LAB allocations only.
100 inline HeapWord* G1ContiguousSpace::par_allocate(size_t min_word_size,
101 size_t desired_word_size,
102 size_t* actual_size) {
103 MutexLocker x(&_par_alloc_lock);
104 return allocate(min_word_size, desired_word_size, actual_size);
105 }
106
107 inline HeapWord* G1ContiguousSpace::block_start(const void* p) {
108 return _bot_part.block_start(p);
109 }
110
111 inline HeapWord*
112 G1ContiguousSpace::block_start_const(const void* p) const {
113 return _bot_part.block_start_const(p);
114 }
115
116 inline bool HeapRegion::is_obj_dead_with_size(const oop obj, G1CMBitMapRO* prev_bitmap, size_t* size) const {
117 HeapWord* addr = (HeapWord*) obj;
118
119 assert(addr < top(), "must be");
120 assert(!is_closed_archive(),
121 "Closed archive regions should not have references into other regions");
122 assert(!is_humongous(), "Humongous objects not handled here");
123 bool obj_is_dead = is_obj_dead(obj, prev_bitmap);
124
125 if (ClassUnloadingWithConcurrentMark && obj_is_dead) {
126 assert(!block_is_obj(addr), "must be");
127 *size = block_size_using_bitmap(addr, prev_bitmap);
128 } else {
129 assert(block_is_obj(addr), "must be");
130 *size = obj->size();
131 }
132 return obj_is_dead;
133 }
134
135 inline bool
136 HeapRegion::block_is_obj(const HeapWord* p) const {
137 G1CollectedHeap* g1h = G1CollectedHeap::heap();
138
139 if (!this->is_in(p)) {
140 assert(is_continues_humongous(), "This case can only happen for humongous regions");
141 return (p == humongous_start_region()->bottom());
142 }
143 if (ClassUnloadingWithConcurrentMark) {
144 return !g1h->is_obj_dead(oop(p), this);
145 }
146 return p < top();
147 }
148
149 inline size_t HeapRegion::block_size_using_bitmap(const HeapWord* addr, const G1CMBitMapRO* prev_bitmap) const {
150 assert(ClassUnloadingWithConcurrentMark,
151 "All blocks should be objects if class unloading isn't used, so this method should not be called. "
152 "HR: [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ") "
153 "addr: " PTR_FORMAT,
154 p2i(bottom()), p2i(top()), p2i(end()), p2i(addr));
155
156 // Old regions' dead objects may have dead classes
157 // We need to find the next live object using the bitmap
158 HeapWord* next = prev_bitmap->getNextMarkedWordAddress(addr, prev_top_at_mark_start());
159
160 assert(next > addr, "must get the next live object");
161 return pointer_delta(next, addr);
162 }
163
164 inline bool HeapRegion::is_obj_dead(const oop obj, const G1CMBitMapRO* prev_bitmap) const {
165 assert(is_in_reserved(obj), "Object " PTR_FORMAT " must be in region", p2i(obj));
166 return !obj_allocated_since_prev_marking(obj) &&
167 !prev_bitmap->isMarked((HeapWord*)obj) &&
168 !is_open_archive();
169 }
170
171 inline size_t HeapRegion::block_size(const HeapWord *addr) const {
172 if (addr == top()) {
173 return pointer_delta(end(), addr);
174 }
175
176 if (block_is_obj(addr)) {
177 return oop(addr)->size();
178 }
179
180 return block_size_using_bitmap(addr, G1CollectedHeap::heap()->concurrent_mark()->prevMarkBitMap());
181 }
182
183 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t min_word_size,
184 size_t desired_word_size,
185 size_t* actual_word_size) {
186 assert(is_young(), "we can only skip BOT updates on young regions");
187 return par_allocate_impl(min_word_size, desired_word_size, actual_word_size);
188 }
189
190 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
191 size_t temp;
192 return allocate_no_bot_updates(word_size, word_size, &temp);
193 }
194
195 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t min_word_size,
196 size_t desired_word_size,
197 size_t* actual_word_size) {
198 assert(is_young(), "we can only skip BOT updates on young regions");
199 return allocate_impl(min_word_size, desired_word_size, actual_word_size);
200 }
201
202 inline void HeapRegion::note_start_of_marking() {
203 _next_marked_bytes = 0;
204 _next_top_at_mark_start = top();
205 }
206
207 inline void HeapRegion::note_end_of_marking() {
208 _prev_top_at_mark_start = _next_top_at_mark_start;
209 _prev_marked_bytes = _next_marked_bytes;
210 _next_marked_bytes = 0;
211 }
212
213 inline void HeapRegion::note_start_of_copying(bool during_initial_mark) {
214 if (is_survivor()) {
215 // This is how we always allocate survivors.
216 assert(_next_top_at_mark_start == bottom(), "invariant");
217 } else {
218 if (during_initial_mark) {
219 // During initial-mark we'll explicitly mark any objects on old
220 // regions that are pointed to by roots. Given that explicit
221 // marks only make sense under NTAMS it'd be nice if we could
222 // check that condition if we wanted to. Given that we don't
223 // know where the top of this region will end up, we simply set
224 // NTAMS to the end of the region so all marks will be below
225 // NTAMS. We'll set it to the actual top when we retire this region.
226 _next_top_at_mark_start = end();
227 } else {
228 // We could have re-used this old region as to-space over a
229 // couple of GCs since the start of the concurrent marking
230 // cycle. This means that [bottom,NTAMS) will contain objects
231 // copied up to and including initial-mark and [NTAMS, top)
232 // will contain objects copied during the concurrent marking cycle.
233 assert(top() >= _next_top_at_mark_start, "invariant");
234 }
235 }
236 }
237
238 inline void HeapRegion::note_end_of_copying(bool during_initial_mark) {
239 if (is_survivor()) {
240 // This is how we always allocate survivors.
241 assert(_next_top_at_mark_start == bottom(), "invariant");
242 } else {
243 if (during_initial_mark) {
244 // See the comment for note_start_of_copying() for the details
245 // on this.
246 assert(_next_top_at_mark_start == end(), "pre-condition");
247 _next_top_at_mark_start = top();
248 } else {
249 // See the comment for note_start_of_copying() for the details
250 // on this.
251 assert(top() >= _next_top_at_mark_start, "invariant");
252 }
253 }
254 }
255
256 inline bool HeapRegion::in_collection_set() const {
257 return G1CollectedHeap::heap()->is_in_cset(this);
258 }
259
260 template <class Closure, bool is_gc_active>
261 bool HeapRegion::do_oops_on_card_in_humongous(MemRegion mr,
262 Closure* cl,
263 G1CollectedHeap* g1h) {
264 assert(is_humongous(), "precondition");
265 HeapRegion* sr = humongous_start_region();
266 oop obj = oop(sr->bottom());
267
268 // If concurrent and klass_or_null is NULL, then space has been
269 // allocated but the object has not yet been published by setting
270 // the klass. That can only happen if the card is stale. However,
271 // we've already set the card clean, so we must return failure,
272 // since the allocating thread could have performed a write to the
273 // card that might be missed otherwise.
274 if (!is_gc_active && (obj->klass_or_null_acquire() == NULL)) {
275 return false;
276 }
277
278 // We have a well-formed humongous object at the start of sr.
279 // Only filler objects follow a humongous object in the containing
280 // regions, and we can ignore those. So only process the one
281 // humongous object.
282 if (!g1h->is_obj_dead(obj, sr)) {
283 if (obj->is_objArray() || (sr->bottom() < mr.start())) {
284 // objArrays are always marked precisely, so limit processing
285 // with mr. Non-objArrays might be precisely marked, and since
286 // it's humongous it's worthwhile avoiding full processing.
287 // However, the card could be stale and only cover filler
288 // objects. That should be rare, so not worth checking for;
289 // instead let it fall out from the bounded iteration.
290 obj->oop_iterate(cl, mr);
291 } else {
292 // If obj is not an objArray and mr contains the start of the
293 // obj, then this could be an imprecise mark, and we need to
294 // process the entire object.
295 obj->oop_iterate(cl);
296 }
297 }
298 return true;
299 }
300
301 template <bool is_gc_active, class Closure>
302 bool HeapRegion::oops_on_card_seq_iterate_careful(MemRegion mr,
303 Closure* cl) {
304 assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
305 G1CollectedHeap* g1h = G1CollectedHeap::heap();
306
307 // Special handling for humongous regions.
308 if (is_humongous()) {
309 return do_oops_on_card_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
310 }
311 assert(is_old(), "precondition");
312
313 // Because mr has been trimmed to what's been allocated in this
314 // region, the parts of the heap that are examined here are always
315 // parsable; there's no need to use klass_or_null to detect
316 // in-progress allocation.
317
318 // Cache the boundaries of the memory region in some const locals
319 HeapWord* const start = mr.start();
320 HeapWord* const end = mr.end();
321
322 // Find the obj that extends onto mr.start().
323 // Update BOT as needed while finding start of (possibly dead)
324 // object containing the start of the region.
325 HeapWord* cur = block_start(start);
326
327 #ifdef ASSERT
328 {
329 assert(cur <= start,
330 "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
331 HeapWord* next = cur + block_size(cur);
332 assert(start < next,
333 "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
334 }
335 #endif
336
337 G1CMBitMapRO* bitmap = g1h->concurrent_mark()->prevMarkBitMap();
338 do {
339 oop obj = oop(cur);
340 assert(obj->is_oop(true), "Not an oop at " PTR_FORMAT, p2i(cur));
341 assert(obj->klass_or_null() != NULL,
342 "Unparsable heap at " PTR_FORMAT, p2i(cur));
343
344 size_t size;
345 bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);
346
347 cur += size;
348 if (!is_dead) {
349 // Process live object's references.
350
351 // Non-objArrays are usually marked imprecise at the object
352 // start, in which case we need to iterate over them in full.
353 // objArrays are precisely marked, but can still be iterated
354 // over in full if completely covered.
355 if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
356 obj->oop_iterate(cl);
357 } else {
358 obj->oop_iterate(cl, mr);
359 }
360 }
361 } while (cur < end);
362
363 return true;
364 }
365
366 #endif // SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP