1 /*
2 * Copyright (c) 2015, Red Hat, Inc. and/or its affiliates.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP
26
27 #include "gc_implementation/g1/concurrentMark.inline.hpp"
28 #include "memory/threadLocalAllocBuffer.inline.hpp"
29 #include "gc_implementation/shenandoah/brooksPointer.inline.hpp"
30 #include "gc_implementation/shenandoah/shenandoahBarrierSet.inline.hpp"
31 #include "gc_implementation/shenandoah/shenandoahHeap.hpp"
32 #include "gc_implementation/shenandoah/shenandoahHeapRegionSet.hpp"
33 #include "gc_implementation/shenandoah/shenandoahHeapRegion.inline.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "runtime/atomic.hpp"
36 #include "runtime/prefetch.hpp"
37 #include "runtime/prefetch.inline.hpp"
38 #include "utilities/copy.hpp"
39
40 template <class T>
41 void SCMUpdateRefsClosure::do_oop_work(T* p) {
42 T o = oopDesc::load_heap_oop(p);
43 if (! oopDesc::is_null(o)) {
44 oop obj = oopDesc::decode_heap_oop_not_null(o);
45 _heap->update_oop_ref_not_null(p, obj);
46 }
47 }
48
49 void SCMUpdateRefsClosure::do_oop(oop* p) { do_oop_work(p); }
50 void SCMUpdateRefsClosure::do_oop(narrowOop* p) { do_oop_work(p); }
51
52 /*
53 * Marks the object. Returns true if the object has not been marked before and has
54 * been marked by this thread. Returns false if the object has already been marked,
55 * or if a competing thread succeeded in marking this object.
56 */
57 inline bool ShenandoahHeap::mark_next(oop obj) const {
58 #ifdef ASSERT
59 if (! oopDesc::unsafe_equals(obj, oopDesc::bs()->read_barrier(obj))) {
60 tty->print_cr("heap region containing obj:");
61 ShenandoahHeapRegion* obj_region = heap_region_containing(obj);
62 obj_region->print();
63 tty->print_cr("heap region containing forwardee:");
64 ShenandoahHeapRegion* forward_region = heap_region_containing(oopDesc::bs()->read_barrier(obj));
65 forward_region->print();
66 }
67 #endif
68
69 assert(oopDesc::unsafe_equals(obj, oopDesc::bs()->read_barrier(obj)), "only mark forwarded copy of objects");
70 return mark_next_no_checks(obj);
71 }
72
73 inline bool ShenandoahHeap::mark_next_no_checks(oop obj) const {
74 HeapWord* addr = (HeapWord*) obj;
75 return (! allocated_after_next_mark_start(addr)) && _next_mark_bit_map->parMark(addr);
76 }
77
78 inline bool ShenandoahHeap::is_marked_next(oop obj) const {
79 HeapWord* addr = (HeapWord*) obj;
80 return allocated_after_next_mark_start(addr) || _next_mark_bit_map->isMarked(addr);
81 }
82
83 inline bool ShenandoahHeap::is_marked_complete(oop obj) const {
84 HeapWord* addr = (HeapWord*) obj;
85 return allocated_after_complete_mark_start(addr) || _complete_mark_bit_map->isMarked(addr);
86 }
87
88 inline bool ShenandoahHeap::need_update_refs() const {
89 return _need_update_refs;
90 }
91
92 inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const {
93 uintptr_t region_start = ((uintptr_t) addr);
94 uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_shift();
95 #ifdef ASSERT
96 if (!(index < _num_regions)) {
97 tty->print_cr("heap region does not contain address, heap base: "PTR_FORMAT \
98 ", real bottom of first region: "PTR_FORMAT", num_regions: "SIZE_FORMAT", region_size: "SIZE_FORMAT,
99 p2i(base()),
100 p2i(_ordered_regions->get(0)->bottom()),
101 _num_regions,
102 ShenandoahHeapRegion::region_size_bytes());
103 }
104 #endif
105 assert(index < _num_regions, "heap region index must be in range");
106 return index;
107 }
108
109 inline ShenandoahHeapRegion* ShenandoahHeap::heap_region_containing(const void* addr) const {
110 size_t index = heap_region_index_containing(addr);
111 ShenandoahHeapRegion* result = _ordered_regions->get(index);
112 #ifdef ASSERT
113 if (!(addr >= result->bottom() && addr < result->end())) {
114 tty->print_cr("heap region does not contain address, heap base: "PTR_FORMAT \
115 ", real bottom of first region: "PTR_FORMAT", num_regions: "SIZE_FORMAT,
116 p2i(base()),
117 p2i(_ordered_regions->get(0)->bottom()),
118 _num_regions);
119 }
120 #endif
121 assert(addr >= result->bottom() && addr < result->end(), "address must be in found region");
122 return result;
123 }
124
125 template <class T>
126 inline oop ShenandoahHeap::update_oop_ref_not_null(T* p, oop obj) {
127 if (in_collection_set(obj)) {
128 oop forw = ShenandoahBarrierSet::resolve_oop_static_not_null(obj);
129 assert(! oopDesc::unsafe_equals(forw, obj) || is_full_gc_in_progress() || cancelled_concgc(), "expect forwarded object");
130 obj = forw;
131 oopDesc::encode_store_heap_oop(p, obj);
132 }
133 #ifdef ASSERT
134 else {
135 assert(oopDesc::unsafe_equals(obj, ShenandoahBarrierSet::resolve_oop_static_not_null(obj)), "expect not forwarded");
136 }
137 #endif
138 return obj;
139 }
140
141 template <class T>
142 inline oop ShenandoahHeap::maybe_update_oop_ref(T* p) {
143 T o = oopDesc::load_heap_oop(p);
144 if (! oopDesc::is_null(o)) {
145 oop obj = oopDesc::decode_heap_oop_not_null(o);
146 return maybe_update_oop_ref_not_null(p, obj);
147 } else {
148 return NULL;
149 }
150 }
151
152 inline oop ShenandoahHeap::atomic_compare_exchange_oop(oop n, oop* addr, oop c) {
153 return (oop) Atomic::cmpxchg_ptr(n, addr, c);
154 }
155
156 inline oop ShenandoahHeap::atomic_compare_exchange_oop(oop n, narrowOop* addr, oop c) {
157 narrowOop cmp = oopDesc::encode_heap_oop(c);
158 narrowOop val = oopDesc::encode_heap_oop(n);
159 return oopDesc::decode_heap_oop((narrowOop) Atomic::cmpxchg(val, addr, cmp));
160 }
161
162 template <class T>
163 inline oop ShenandoahHeap::maybe_update_oop_ref_not_null(T* p, oop heap_oop) {
164
165 assert((! is_in(p)) || (! in_collection_set(p))
166 || is_full_gc_in_progress(),
167 "never update refs in from-space, unless evacuation has been cancelled");
168
169 #ifdef ASSERT
170 if (! is_in(heap_oop)) {
171 print_heap_regions();
172 tty->print_cr("object not in heap: "PTR_FORMAT", referenced by: "PTR_FORMAT, p2i((HeapWord*) heap_oop), p2i(p));
173 assert(is_in(heap_oop), "object must be in heap");
174 }
175 #endif
176 assert(is_in(heap_oop), "only ever call this on objects in the heap");
177 if (in_collection_set(heap_oop)) {
178 oop forwarded_oop = ShenandoahBarrierSet::resolve_oop_static_not_null(heap_oop); // read brooks ptr
179 assert(! oopDesc::unsafe_equals(forwarded_oop, heap_oop) || is_full_gc_in_progress(), "expect forwarded object");
180
181 log_develop_trace(gc)("Updating old ref: "PTR_FORMAT" pointing to "PTR_FORMAT" to new ref: "PTR_FORMAT,
182 p2i(p), p2i(heap_oop), p2i(forwarded_oop));
183
184 assert(forwarded_oop->is_oop(), "oop required");
185 assert(is_in(forwarded_oop), "forwardee must be in heap");
186 assert(oopDesc::bs()->is_safe(forwarded_oop), "forwardee must not be in collection set");
187 // If this fails, another thread wrote to p before us, it will be logged in SATB and the
188 // reference be updated later.
189 oop result = atomic_compare_exchange_oop(forwarded_oop, p, heap_oop);
190
191 if (oopDesc::unsafe_equals(result, heap_oop)) { // CAS successful.
192 return forwarded_oop;
193 } else {
194 return NULL;
195 }
196 } else {
197 assert(oopDesc::unsafe_equals(heap_oop, ShenandoahBarrierSet::resolve_oop_static_not_null(heap_oop)),
198 "expect not forwarded");
199 return heap_oop;
200 }
201 }
202
203 inline bool ShenandoahHeap::cancelled_concgc() const {
204 return OrderAccess::load_acquire((jbyte*) &_cancelled_concgc) == 1;
205 }
206
207 inline bool ShenandoahHeap::try_cancel_concgc() {
208 return Atomic::cmpxchg(1, &_cancelled_concgc, 0) == 0;
209 }
210
211 inline void ShenandoahHeap::clear_cancelled_concgc() {
212 OrderAccess::release_store_fence(&_cancelled_concgc, 0);
213 }
214
215 inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) {
216 if (UseTLAB) {
217 HeapWord* obj = thread->gclab().allocate(size);
218 if (obj != NULL) {
219 return obj;
220 }
221 // Otherwise...
222 return allocate_from_gclab_slow(thread, size);
223 } else {
224 return NULL;
225 }
226 }
227
228 inline void ShenandoahHeap::copy_object(oop p, HeapWord* s, size_t words) {
229 assert(s != NULL, "allocation of brooks pointer must not fail");
230 HeapWord* copy = s + BrooksPointer::word_size();
231
232 guarantee(copy != NULL, "allocation of copy object must not fail");
233 Copy::aligned_disjoint_words((HeapWord*) p, copy, words);
234 BrooksPointer::initialize(oop(copy));
235
236 log_develop_trace(gc, compaction)("copy object from "PTR_FORMAT" to: "PTR_FORMAT, p2i((HeapWord*) p), p2i(copy));
237 }
238
239 inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread, bool& evacuated) {
240 evacuated = false;
241
242 size_t required = BrooksPointer::word_size() + p->size();
243
244 assert(! heap_region_containing(p)->is_humongous(), "never evacuate humongous objects");
245
246 bool alloc_from_gclab = true;
247 HeapWord* filler = allocate_from_gclab(thread, required);
248 if (filler == NULL) {
249 filler = allocate_memory(required, true);
250 alloc_from_gclab = false;
251 }
252
253 #ifdef ASSERT
254 // Checking that current Java thread does not hold Threads_lock when we get here.
255 // If that ever be the case, we'd deadlock in oom_during_evacuation.
256 if ((! Thread::current()->is_GC_task_thread()) && (! Thread::current()->is_ConcurrentGC_thread())) {
257 assert(! Threads_lock->owned_by_self(), "must not hold Threads_lock here");
258 }
259 #endif
260
261 if (filler == NULL) {
262 oom_during_evacuation();
263 // If this is a Java thread, it should have waited
264 // until all GC threads are done, and then we
265 // return the forwardee.
266 oop resolved = ShenandoahBarrierSet::resolve_oop_static(p);
267 return resolved;
268 }
269
270 HeapWord* copy = filler + BrooksPointer::word_size();
271 copy_object(p, filler, required - BrooksPointer::word_size());
272
273 oop copy_val = oop(copy);
274 oop result = BrooksPointer::try_update_forwardee(p, copy_val);
275
276 oop return_val;
277 if (oopDesc::unsafe_equals(result, p)) {
278 evacuated = true;
279 return_val = copy_val;
280
281 log_develop_trace(gc, compaction)("Copy of "PTR_FORMAT" to "PTR_FORMAT" succeeded \n",
282 p2i((HeapWord*) p), p2i(copy));
283
284 #ifdef ASSERT
285 assert(return_val->is_oop(), "expect oop");
286 assert(p->klass() == return_val->klass(), err_msg("Should have the same class p: "PTR_FORMAT", copy: "PTR_FORMAT,
287 p2i((HeapWord*) p), p2i((HeapWord*) copy)));
288 #endif
289 } else {
290 if (alloc_from_gclab) {
291 thread->gclab().rollback(required);
292 }
293 log_develop_trace(gc, compaction)("Copy of "PTR_FORMAT" to "PTR_FORMAT" failed, use other: "PTR_FORMAT,
294 p2i((HeapWord*) p), p2i(copy), p2i((HeapWord*) result));
295 return_val = result;
296 }
297
298 return return_val;
299 }
300
301 inline bool ShenandoahHeap::requires_marking(const void* entry) const {
302 return ! is_marked_next(oop(entry));
303 }
304
305 bool ShenandoahHeap::region_in_collection_set(size_t region_index) const {
306 return _in_cset_fast_test_base[region_index];
307 }
308
309 bool ShenandoahHeap::in_collection_set(ShenandoahHeapRegion* r) const {
310 return region_in_collection_set(r->region_number());
311 }
312
313 template <class T>
314 inline bool ShenandoahHeap::in_collection_set(T p) const {
315 HeapWord* obj = (HeapWord*) p;
316 assert(_in_cset_fast_test != NULL, "sanity");
317 assert(is_in(obj), "should be in heap");
318
319 // no need to subtract the bottom of the heap from obj,
320 // _in_cset_fast_test is biased
321 uintx index = ((uintx) obj) >> ShenandoahHeapRegion::region_size_shift();
322 return _in_cset_fast_test[index];
323 }
324
325 inline bool ShenandoahHeap::concurrent_mark_in_progress() {
326 return _concurrent_mark_in_progress != 0;
327 }
328
329 inline address ShenandoahHeap::concurrent_mark_in_progress_addr() {
330 return (address) &(ShenandoahHeap::heap()->_concurrent_mark_in_progress);
331 }
332
333 inline bool ShenandoahHeap::is_evacuation_in_progress() {
334 return _evacuation_in_progress != 0;
335 }
336
337 inline bool ShenandoahHeap::allocated_after_next_mark_start(HeapWord* addr) const {
338 uintx index = ((uintx) addr) >> ShenandoahHeapRegion::region_size_shift();
339 HeapWord* top_at_mark_start = _next_top_at_mark_starts[index];
340 bool alloc_after_mark_start = addr >= top_at_mark_start;
341 return alloc_after_mark_start;
342 }
343
344 inline bool ShenandoahHeap::allocated_after_complete_mark_start(HeapWord* addr) const {
345 uintx index = ((uintx) addr) >> ShenandoahHeapRegion::region_size_shift();
346 HeapWord* top_at_mark_start = _complete_top_at_mark_starts[index];
347 bool alloc_after_mark_start = addr >= top_at_mark_start;
348 return alloc_after_mark_start;
349 }
350
351 template<class T>
352 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) {
353 assert(BrooksPointer::word_offset() < 0, "skip_delta calculation below assumes the forwarding ptr is before obj");
354
355 CMBitMap* mark_bit_map = _complete_mark_bit_map;
356 HeapWord* top_at_mark_start = complete_top_at_mark_start(region->bottom());
357
358 size_t skip_bitmap_delta = BrooksPointer::word_size() + 1;
359 size_t skip_objsize_delta = BrooksPointer::word_size() /* + actual obj.size() below */;
360 HeapWord* start = region->bottom() + BrooksPointer::word_size();
361
362 HeapWord* limit = region->top();
363 HeapWord* end = MIN2(top_at_mark_start + BrooksPointer::word_size(), _ordered_regions->end());
364 HeapWord* addr = mark_bit_map->getNextMarkedWordAddress(start, end);
365
366 intx dist = ShenandoahMarkScanPrefetch;
367 if (dist > 0) {
368 // Batched scan that prefetches the oop data, anticipating the access to
369 // either header, oop field, or forwarding pointer. Not that we cannot
370 // touch anything in oop, while it still being prefetched to get enough
371 // time for prefetch to work. This is why we try to scan the bitmap linearly,
372 // disregarding the object size. However, since we know forwarding pointer
373 // preceeds the object, we can skip over it. Once we cannot trust the bitmap,
374 // there is no point for prefetching the oop contents, as oop->size() will
375 // touch it prematurely.
376
377 // No variable-length arrays in standard C++, have enough slots to fit
378 // the prefetch distance.
379 static const int SLOT_COUNT = 256;
380 guarantee(dist <= SLOT_COUNT, "adjust slot count");
381 oop slots[SLOT_COUNT];
382
383 bool aborting = false;
384 int avail;
385 do {
386 avail = 0;
387 for (int c = 0; (c < dist) && (addr < limit); c++) {
388 Prefetch::read(addr, BrooksPointer::byte_offset());
389 oop obj = oop(addr);
390 slots[avail++] = obj;
391 if (addr < top_at_mark_start) {
392 addr += skip_bitmap_delta;
393 addr = mark_bit_map->getNextMarkedWordAddress(addr, end);
394 } else {
395 // cannot trust mark bitmap anymore, finish the current stride,
396 // and switch to accurate traversal
397 addr += obj->size() + skip_objsize_delta;
398 aborting = true;
399 }
400 }
401
402 for (int c = 0; c < avail; c++) {
403 do_marked_object(mark_bit_map, cl, slots[c]);
404 }
405 } while (avail > 0 && !aborting);
406
407 // accurate traversal
408 while (addr < limit) {
409 oop obj = oop(addr);
410 int size = obj->size();
411 do_marked_object(mark_bit_map, cl, obj);
412 addr += size + skip_objsize_delta;
413 }
414 } else {
415 while (addr < limit) {
416 oop obj = oop(addr);
417 int size = obj->size();
418 do_marked_object(mark_bit_map, cl, obj);
419 addr += size + skip_objsize_delta;
420 if (addr < top_at_mark_start) {
421 addr = mark_bit_map->getNextMarkedWordAddress(addr, end);
422 }
423 }
424 }
425 }
426
427 template<class T>
428 inline void ShenandoahHeap::do_marked_object(CMBitMap* bitmap, T* cl, oop obj) {
429 #ifdef ASSERT
430 assert(!oopDesc::is_null(obj), "sanity");
431 assert(obj->is_oop(), "sanity");
432 assert(is_in(obj), "sanity");
433 assert(bitmap == _complete_mark_bit_map, "only iterate completed mark bitmap");
434 assert(is_marked_complete(obj), "object expected to be marked");
435 #endif
436 cl->do_object(obj);
437 }
438
439 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP