1 /*
2 * Copyright (c) 2001, 2018, 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.
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_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/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 void HeapRegion::note_start_of_copying(bool during_initial_mark) {
256 if (is_survivor()) {
257 // This is how we always allocate survivors.
258 assert(_next_top_at_mark_start == bottom(), "invariant");
259 } else {
260 if (during_initial_mark) {
261 // During initial-mark we'll explicitly mark any objects on old
262 // regions that are pointed to by roots. Given that explicit
263 // marks only make sense under NTAMS it'd be nice if we could
264 // check that condition if we wanted to. Given that we don't
265 // know where the top of this region will end up, we simply set
266 // NTAMS to the end of the region so all marks will be below
267 // NTAMS. We'll set it to the actual top when we retire this region.
268 _next_top_at_mark_start = end();
269 } else {
270 // We could have re-used this old region as to-space over a
271 // couple of GCs since the start of the concurrent marking
272 // cycle. This means that [bottom,NTAMS) will contain objects
273 // copied up to and including initial-mark and [NTAMS, top)
274 // will contain objects copied during the concurrent marking cycle.
275 assert(top() >= _next_top_at_mark_start, "invariant");
276 }
277 }
278 }
279
280 inline void HeapRegion::note_end_of_copying(bool during_initial_mark) {
281 if (is_survivor()) {
282 // This is how we always allocate survivors.
283 assert(_next_top_at_mark_start == bottom(), "invariant");
284 } else {
285 if (during_initial_mark) {
286 // See the comment for note_start_of_copying() for the details
287 // on this.
288 assert(_next_top_at_mark_start == end(), "pre-condition");
289 _next_top_at_mark_start = top();
290 } else {
291 // See the comment for note_start_of_copying() for the details
292 // on this.
293 assert(top() >= _next_top_at_mark_start, "invariant");
294 }
295 }
296 }
297
298 inline bool HeapRegion::in_collection_set() const {
299 return G1CollectedHeap::heap()->is_in_cset(this);
300 }
301
302 template <class Closure, bool is_gc_active>
303 bool HeapRegion::do_oops_on_card_in_humongous(MemRegion mr,
304 Closure* cl,
305 G1CollectedHeap* g1h) {
306 assert(is_humongous(), "precondition");
307 HeapRegion* sr = humongous_start_region();
308 oop obj = oop(sr->bottom());
309
310 // If concurrent and klass_or_null is NULL, then space has been
311 // allocated but the object has not yet been published by setting
312 // the klass. That can only happen if the card is stale. However,
313 // we've already set the card clean, so we must return failure,
314 // since the allocating thread could have performed a write to the
315 // card that might be missed otherwise.
316 if (!is_gc_active && (obj->klass_or_null_acquire() == NULL)) {
317 return false;
318 }
319
320 // We have a well-formed humongous object at the start of sr.
321 // Only filler objects follow a humongous object in the containing
322 // regions, and we can ignore those. So only process the one
323 // humongous object.
324 if (!g1h->is_obj_dead(obj, sr)) {
325 if (obj->is_objArray() || (sr->bottom() < mr.start())) {
326 // objArrays are always marked precisely, so limit processing
327 // with mr. Non-objArrays might be precisely marked, and since
328 // it's humongous it's worthwhile avoiding full processing.
329 // However, the card could be stale and only cover filler
330 // objects. That should be rare, so not worth checking for;
331 // instead let it fall out from the bounded iteration.
332 obj->oop_iterate(cl, mr);
333 } else {
334 // If obj is not an objArray and mr contains the start of the
335 // obj, then this could be an imprecise mark, and we need to
336 // process the entire object.
337 obj->oop_iterate(cl);
338 }
339 }
340 return true;
341 }
342
343 template <bool is_gc_active, class Closure>
344 bool HeapRegion::oops_on_card_seq_iterate_careful(MemRegion mr,
345 Closure* cl) {
346 assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
347 G1CollectedHeap* g1h = G1CollectedHeap::heap();
348
349 // Special handling for humongous regions.
350 if (is_humongous()) {
351 return do_oops_on_card_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
352 }
353 assert(is_old() || is_archive(), "Wrongly trying to iterate over region %u type %s", _hrm_index, get_type_str());
354
355 // Because mr has been trimmed to what's been allocated in this
356 // region, the parts of the heap that are examined here are always
357 // parsable; there's no need to use klass_or_null to detect
358 // in-progress allocation.
359
360 // Cache the boundaries of the memory region in some const locals
361 HeapWord* const start = mr.start();
362 HeapWord* const end = mr.end();
363
364 // Find the obj that extends onto mr.start().
365 // Update BOT as needed while finding start of (possibly dead)
366 // object containing the start of the region.
367 HeapWord* cur = block_start(start);
368
369 #ifdef ASSERT
370 {
371 assert(cur <= start,
372 "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
373 HeapWord* next = cur + block_size(cur);
374 assert(start < next,
375 "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
376 }
377 #endif
378
379 const G1CMBitMap* const bitmap = g1h->concurrent_mark()->prev_mark_bitmap();
380 do {
381 oop obj = oop(cur);
382 assert(oopDesc::is_oop(obj, true), "Not an oop at " PTR_FORMAT, p2i(cur));
383 assert(obj->klass_or_null() != NULL,
384 "Unparsable heap at " PTR_FORMAT, p2i(cur));
385
386 size_t size;
387 bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);
388
389 cur += size;
390 if (!is_dead) {
391 // Process live object's references.
392
393 // Non-objArrays are usually marked imprecise at the object
394 // start, in which case we need to iterate over them in full.
395 // objArrays are precisely marked, but can still be iterated
396 // over in full if completely covered.
397 if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
398 obj->oop_iterate(cl);
399 } else {
400 obj->oop_iterate(cl, mr);
401 }
402 }
403 } while (cur < end);
404
405 return true;
406 }
407
408 #endif // SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP