1 /*
2 * Copyright (c) 2001, 2019, 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_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 "runtime/mutexLocker.inline.hpp"
37 #include "utilities/align.hpp"
38
39 inline HeapWord* G1ContiguousSpace::allocate_impl(size_t min_word_size,
40 size_t desired_word_size,
41 size_t* actual_size) {
42 HeapWord* obj = top();
43 size_t available = pointer_delta(end(), obj);
44 size_t want_to_allocate = MIN2(available, desired_word_size);
45 if (want_to_allocate >= min_word_size) {
46 HeapWord* new_top = obj + want_to_allocate;
47 set_top(new_top);
48 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
49 *actual_size = want_to_allocate;
50 return obj;
51 } else {
52 return NULL;
53 }
54 }
55
56 inline HeapWord* G1ContiguousSpace::par_allocate_impl(size_t min_word_size,
57 size_t desired_word_size,
58 size_t* actual_size) {
59 do {
60 HeapWord* obj = top();
61 size_t available = pointer_delta(end(), obj);
62 size_t want_to_allocate = MIN2(available, desired_word_size);
63 if (want_to_allocate >= min_word_size) {
64 HeapWord* new_top = obj + want_to_allocate;
65 HeapWord* result = Atomic::cmpxchg(new_top, top_addr(), obj);
66 // result can be one of two:
67 // the old top value: the exchange succeeded
68 // otherwise: the new value of the top is returned.
69 if (result == obj) {
70 assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
71 *actual_size = want_to_allocate;
72 return obj;
73 }
74 } else {
75 return NULL;
76 }
77 } while (true);
78 }
79
80 inline HeapWord* G1ContiguousSpace::allocate(size_t min_word_size,
81 size_t desired_word_size,
82 size_t* actual_size) {
83 HeapWord* res = allocate_impl(min_word_size, desired_word_size, actual_size);
84 if (res != NULL) {
85 _bot_part.alloc_block(res, *actual_size);
86 }
87 return res;
88 }
89
90 inline HeapWord* G1ContiguousSpace::allocate(size_t word_size) {
91 size_t temp;
92 return allocate(word_size, word_size, &temp);
93 }
94
95 inline HeapWord* G1ContiguousSpace::par_allocate(size_t word_size) {
96 size_t temp;
97 return par_allocate(word_size, word_size, &temp);
98 }
99
100 // Because of the requirement of keeping "_offsets" up to date with the
101 // allocations, we sequentialize these with a lock. Therefore, best if
102 // this is used for larger LAB allocations only.
103 inline HeapWord* G1ContiguousSpace::par_allocate(size_t min_word_size,
104 size_t desired_word_size,
105 size_t* actual_size) {
106 MutexLocker x(&_par_alloc_lock);
107 return allocate(min_word_size, desired_word_size, actual_size);
108 }
109
110 inline HeapWord* G1ContiguousSpace::block_start(const void* p) {
111 return _bot_part.block_start(p);
112 }
113
114 inline HeapWord*
115 G1ContiguousSpace::block_start_const(const void* p) const {
116 return _bot_part.block_start_const(p);
117 }
118
119 inline bool HeapRegion::is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const {
120 HeapWord* addr = (HeapWord*) obj;
121
122 assert(addr < top(), "must be");
123 assert(!is_closed_archive(),
124 "Closed archive regions should not have references into other regions");
125 assert(!is_humongous(), "Humongous objects not handled here");
126 bool obj_is_dead = is_obj_dead(obj, prev_bitmap);
127
128 if (ClassUnloadingWithConcurrentMark && obj_is_dead) {
129 assert(!block_is_obj(addr), "must be");
130 *size = block_size_using_bitmap(addr, prev_bitmap);
131 } else {
132 assert(block_is_obj(addr), "must be");
133 *size = obj->size();
134 }
135 return obj_is_dead;
136 }
137
138 inline bool
139 HeapRegion::block_is_obj(const HeapWord* p) const {
140 G1CollectedHeap* g1h = G1CollectedHeap::heap();
141
142 if (!this->is_in(p)) {
143 assert(is_continues_humongous(), "This case can only happen for humongous regions");
144 return (p == humongous_start_region()->bottom());
145 }
146 if (ClassUnloadingWithConcurrentMark) {
147 return !g1h->is_obj_dead(oop(p), this);
148 }
149 return p < top();
150 }
151
152 inline size_t HeapRegion::block_size_using_bitmap(const HeapWord* addr, const G1CMBitMap* const prev_bitmap) const {
153 assert(ClassUnloadingWithConcurrentMark,
154 "All blocks should be objects if class unloading isn't used, so this method should not be called. "
155 "HR: [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ") "
156 "addr: " PTR_FORMAT,
157 p2i(bottom()), p2i(top()), p2i(end()), p2i(addr));
158
159 // Old regions' dead objects may have dead classes
160 // We need to find the next live object using the bitmap
161 HeapWord* next = prev_bitmap->get_next_marked_addr(addr, prev_top_at_mark_start());
162
163 assert(next > addr, "must get the next live object");
164 return pointer_delta(next, addr);
165 }
166
167 inline bool HeapRegion::is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const {
168 assert(is_in_reserved(obj), "Object " PTR_FORMAT " must be in region", p2i(obj));
169 return !obj_allocated_since_prev_marking(obj) &&
170 !prev_bitmap->is_marked((HeapWord*)obj) &&
171 !is_open_archive();
172 }
173
174 inline size_t HeapRegion::block_size(const HeapWord *addr) const {
175 if (addr == top()) {
176 return pointer_delta(end(), addr);
177 }
178
179 if (block_is_obj(addr)) {
180 return oop(addr)->size();
181 }
182
183 return block_size_using_bitmap(addr, G1CollectedHeap::heap()->concurrent_mark()->prev_mark_bitmap());
184 }
185
186 inline void HeapRegion::complete_compaction() {
187 // Reset space and bot after compaction is complete if needed.
188 reset_after_compaction();
189 if (used_region().is_empty()) {
190 reset_bot();
191 }
192
193 // After a compaction the mark bitmap is invalid, so we must
194 // treat all objects as being inside the unmarked area.
195 zero_marked_bytes();
196 init_top_at_mark_start();
197
198 // Clear unused heap memory in debug builds.
199 if (ZapUnusedHeapArea) {
200 mangle_unused_area();
201 }
202 }
203
204 template<typename ApplyToMarkedClosure>
205 inline void HeapRegion::apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure) {
206 HeapWord* limit = scan_limit();
207 HeapWord* next_addr = bottom();
208
209 while (next_addr < limit) {
210 Prefetch::write(next_addr, PrefetchScanIntervalInBytes);
211 // This explicit is_marked check is a way to avoid
212 // some extra work done by get_next_marked_addr for
213 // the case where next_addr is marked.
214 if (bitmap->is_marked(next_addr)) {
215 oop current = oop(next_addr);
216 next_addr += closure->apply(current);
217 } else {
218 next_addr = bitmap->get_next_marked_addr(next_addr, limit);
219 }
220 }
221
222 assert(next_addr == limit, "Should stop the scan at the limit.");
223 }
224
225 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t min_word_size,
226 size_t desired_word_size,
227 size_t* actual_word_size) {
228 assert(is_young(), "we can only skip BOT updates on young regions");
229 return par_allocate_impl(min_word_size, desired_word_size, actual_word_size);
230 }
231
232 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
233 size_t temp;
234 return allocate_no_bot_updates(word_size, word_size, &temp);
235 }
236
237 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t min_word_size,
238 size_t desired_word_size,
239 size_t* actual_word_size) {
240 assert(is_young(), "we can only skip BOT updates on young regions");
241 return allocate_impl(min_word_size, desired_word_size, actual_word_size);
242 }
243
244 inline void HeapRegion::note_start_of_marking() {
245 _next_marked_bytes = 0;
246 _next_top_at_mark_start = top();
247 }
248
249 inline void HeapRegion::note_end_of_marking() {
250 _prev_top_at_mark_start = _next_top_at_mark_start;
251 _next_top_at_mark_start = bottom();
252 _prev_marked_bytes = _next_marked_bytes;
253 _next_marked_bytes = 0;
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 HeapWord* HeapRegion::do_oops_on_memregion_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 NULL;
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 // The object is dead. There can be no other object in this region, so return
284 // the end of that region.
285 return end();
286 }
287 if (obj->is_objArray() || (sr->bottom() < mr.start())) {
288 // objArrays are always marked precisely, so limit processing
289 // with mr. Non-objArrays might be precisely marked, and since
290 // it's humongous it's worthwhile avoiding full processing.
291 // However, the card could be stale and only cover filler
292 // objects. That should be rare, so not worth checking for;
293 // instead let it fall out from the bounded iteration.
294 obj->oop_iterate(cl, mr);
295 return mr.end();
296 } else {
297 // If obj is not an objArray and mr contains the start of the
298 // obj, then this could be an imprecise mark, and we need to
299 // process the entire object.
300 int size = obj->oop_iterate_size(cl);
301 // We have scanned to the end of the object, but since there can be no objects
302 // after this humongous object in the region, we can return the end of the
303 // region if it is greater.
304 return MAX2((HeapWord*)obj + size, mr.end());
305 }
306 }
307
308 template <bool is_gc_active, class Closure>
309 HeapWord* HeapRegion::oops_on_memregion_seq_iterate_careful(MemRegion mr,
310 Closure* cl) {
311 assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
312 G1CollectedHeap* g1h = G1CollectedHeap::heap();
313
314 // Special handling for humongous regions.
315 if (is_humongous()) {
316 return do_oops_on_memregion_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
317 }
318 assert(is_old() || is_archive(), "Wrongly trying to iterate over region %u type %s", _hrm_index, get_type_str());
319
320 // Because mr has been trimmed to what's been allocated in this
321 // region, the parts of the heap that are examined here are always
322 // parsable; there's no need to use klass_or_null to detect
323 // in-progress allocation.
324
325 // Cache the boundaries of the memory region in some const locals
326 HeapWord* const start = mr.start();
327 HeapWord* const end = mr.end();
328
329 // Find the obj that extends onto mr.start().
330 // Update BOT as needed while finding start of (possibly dead)
331 // object containing the start of the region.
332 HeapWord* cur = block_start(start);
333
334 #ifdef ASSERT
335 {
336 assert(cur <= start,
337 "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
338 HeapWord* next = cur + block_size(cur);
339 assert(start < next,
340 "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
341 }
342 #endif
343
344 const G1CMBitMap* const bitmap = g1h->concurrent_mark()->prev_mark_bitmap();
345 while (true) {
346 oop obj = oop(cur);
347 assert(oopDesc::is_oop(obj, true), "Not an oop at " PTR_FORMAT, p2i(cur));
348 assert(obj->klass_or_null() != NULL,
349 "Unparsable heap at " PTR_FORMAT, p2i(cur));
350
351 size_t size;
352 bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);
353 bool is_precise = false;
354
355 cur += size;
356 if (!is_dead) {
357 // Process live object's references.
358
359 // Non-objArrays are usually marked imprecise at the object
360 // start, in which case we need to iterate over them in full.
361 // objArrays are precisely marked, but can still be iterated
362 // over in full if completely covered.
363 if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
364 obj->oop_iterate(cl);
365 } else {
366 obj->oop_iterate(cl, mr);
367 is_precise = true;
368 }
369 }
370 if (cur >= end) {
371 return is_precise ? end : cur;
372 }
373 }
374 }
375
376 #endif // SHARE_GC_G1_HEAPREGION_INLINE_HPP