1 /* 2 * Copyright (c) 2015, 2020, Red Hat, Inc. 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_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP 26 #define SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP 27 28 #include "classfile/javaClasses.inline.hpp" 29 #include "gc/shared/markBitMap.inline.hpp" 30 #include "gc/shared/threadLocalAllocBuffer.inline.hpp" 31 #include "gc/shared/suspendibleThreadSet.hpp" 32 #include "gc/shenandoah/shenandoahAsserts.hpp" 33 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp" 34 #include "gc/shenandoah/shenandoahCollectionSet.inline.hpp" 35 #include "gc/shenandoah/shenandoahForwarding.inline.hpp" 36 #include "gc/shenandoah/shenandoahWorkGroup.hpp" 37 #include "gc/shenandoah/shenandoahHeap.hpp" 38 #include "gc/shenandoah/shenandoahHeapRegionSet.inline.hpp" 39 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp" 40 #include "gc/shenandoah/shenandoahControlThread.hpp" 41 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 42 #include "gc/shenandoah/shenandoahThreadLocalData.hpp" 43 #include "oops/compressedOops.inline.hpp" 44 #include "oops/oop.inline.hpp" 45 #include "runtime/atomic.hpp" 46 #include "runtime/prefetch.inline.hpp" 47 #include "runtime/thread.hpp" 48 #include "utilities/copy.hpp" 49 #include "utilities/globalDefinitions.hpp" 50 51 52 inline ShenandoahHeapRegion* ShenandoahRegionIterator::next() { 53 size_t new_index = Atomic::add(&_index, (size_t) 1); 54 // get_region() provides the bounds-check and returns NULL on OOB. 55 return _heap->get_region(new_index - 1); 56 } 57 58 inline bool ShenandoahHeap::has_forwarded_objects() const { 59 return _gc_state.is_set(HAS_FORWARDED); 60 } 61 62 inline WorkGang* ShenandoahHeap::workers() const { 63 return _workers; 64 } 65 66 inline WorkGang* ShenandoahHeap::get_safepoint_workers() { 67 return _safepoint_workers; 68 } 69 70 inline size_t ShenandoahHeap::heap_region_index_containing(const void* addr) const { 71 uintptr_t region_start = ((uintptr_t) addr); 72 uintptr_t index = (region_start - (uintptr_t) base()) >> ShenandoahHeapRegion::region_size_bytes_shift(); 73 assert(index < num_regions(), "Region index is in bounds: " PTR_FORMAT, p2i(addr)); 74 return index; 75 } 76 77 inline ShenandoahHeapRegion* const ShenandoahHeap::heap_region_containing(const void* addr) const { 78 size_t index = heap_region_index_containing(addr); 79 ShenandoahHeapRegion* const result = get_region(index); 80 assert(addr >= result->bottom() && addr < result->end(), "Heap region contains the address: " PTR_FORMAT, p2i(addr)); 81 return result; 82 } 83 84 template <class T> 85 inline oop ShenandoahHeap::update_with_forwarded_not_null(T* p, oop obj) { 86 if (in_collection_set(obj)) { 87 shenandoah_assert_forwarded_except(p, obj, is_full_gc_in_progress() || cancelled_gc() || is_degenerated_gc_in_progress()); 88 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj); 89 RawAccess<IS_NOT_NULL>::oop_store(p, obj); 90 } 91 #ifdef ASSERT 92 else { 93 shenandoah_assert_not_forwarded(p, obj); 94 } 95 #endif 96 return obj; 97 } 98 99 template <class T> 100 inline oop ShenandoahHeap::maybe_update_with_forwarded(T* p) { 101 T o = RawAccess<>::oop_load(p); 102 if (!CompressedOops::is_null(o)) { 103 oop obj = CompressedOops::decode_not_null(o); 104 return maybe_update_with_forwarded_not_null(p, obj); 105 } else { 106 return NULL; 107 } 108 } 109 110 template <class T> 111 inline oop ShenandoahHeap::evac_update_with_forwarded(T* p) { 112 T o = RawAccess<>::oop_load(p); 113 if (!CompressedOops::is_null(o)) { 114 oop heap_oop = CompressedOops::decode_not_null(o); 115 if (in_collection_set(heap_oop)) { 116 oop forwarded_oop = ShenandoahBarrierSet::resolve_forwarded_not_null(heap_oop); 117 if (forwarded_oop == heap_oop) { 118 forwarded_oop = evacuate_object(heap_oop, Thread::current()); 119 } 120 oop prev = cas_oop(forwarded_oop, p, heap_oop); 121 if (prev == heap_oop) { 122 return forwarded_oop; 123 } else { 124 return NULL; 125 } 126 } 127 return heap_oop; 128 } else { 129 return NULL; 130 } 131 } 132 133 inline oop ShenandoahHeap::cas_oop(oop n, oop* addr, oop c) { 134 assert(is_aligned(addr, HeapWordSize), "Address should be aligned: " PTR_FORMAT, p2i(addr)); 135 return (oop) Atomic::cmpxchg(addr, c, n); 136 } 137 138 inline oop ShenandoahHeap::cas_oop(oop n, narrowOop* addr, narrowOop c) { 139 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr)); 140 narrowOop val = CompressedOops::encode(n); 141 return CompressedOops::decode((narrowOop) Atomic::cmpxchg(addr, c, val)); 142 } 143 144 inline oop ShenandoahHeap::cas_oop(oop n, narrowOop* addr, oop c) { 145 assert(is_aligned(addr, sizeof(narrowOop)), "Address should be aligned: " PTR_FORMAT, p2i(addr)); 146 narrowOop cmp = CompressedOops::encode(c); 147 narrowOop val = CompressedOops::encode(n); 148 return CompressedOops::decode((narrowOop) Atomic::cmpxchg(addr, cmp, val)); 149 } 150 151 template <class T> 152 inline oop ShenandoahHeap::maybe_update_with_forwarded_not_null(T* p, oop heap_oop) { 153 shenandoah_assert_not_in_cset_loc_except(p, !is_in(p) || is_full_gc_in_progress() || is_degenerated_gc_in_progress()); 154 shenandoah_assert_correct(p, heap_oop); 155 156 if (in_collection_set(heap_oop)) { 157 oop forwarded_oop = ShenandoahBarrierSet::resolve_forwarded_not_null(heap_oop); 158 if (forwarded_oop == heap_oop) { 159 // E.g. during evacuation. 160 return forwarded_oop; 161 } 162 163 shenandoah_assert_forwarded_except(p, heap_oop, is_full_gc_in_progress() || is_degenerated_gc_in_progress()); 164 shenandoah_assert_not_forwarded(p, forwarded_oop); 165 shenandoah_assert_not_in_cset_except(p, forwarded_oop, cancelled_gc()); 166 167 // If this fails, another thread wrote to p before us, it will be logged in SATB and the 168 // reference be updated later. 169 oop witness = cas_oop(forwarded_oop, p, heap_oop); 170 171 if (witness != heap_oop) { 172 // CAS failed, someone had beat us to it. Normally, we would return the failure witness, 173 // because that would be the proper write of to-space object, enforced by strong barriers. 174 // However, there is a corner case with arraycopy. It can happen that a Java thread 175 // beats us with an arraycopy, which first copies the array, which potentially contains 176 // from-space refs, and only afterwards updates all from-space refs to to-space refs, 177 // which leaves a short window where the new array elements can be from-space. 178 // In this case, we can just resolve the result again. As we resolve, we need to consider 179 // the contended write might have been NULL. 180 oop result = ShenandoahBarrierSet::resolve_forwarded(witness); 181 shenandoah_assert_not_forwarded_except(p, result, (result == NULL)); 182 shenandoah_assert_not_in_cset_except(p, result, (result == NULL) || cancelled_gc()); 183 return result; 184 } else { 185 // Success! We have updated with known to-space copy. We have already asserted it is sane. 186 return forwarded_oop; 187 } 188 } else { 189 shenandoah_assert_not_forwarded(p, heap_oop); 190 return heap_oop; 191 } 192 } 193 194 inline bool ShenandoahHeap::cancelled_gc() const { 195 return _cancelled_gc.get() == CANCELLED; 196 } 197 198 inline bool ShenandoahHeap::check_cancelled_gc_and_yield(bool sts_active) { 199 if (! (sts_active && ShenandoahSuspendibleWorkers)) { 200 return cancelled_gc(); 201 } 202 203 jbyte prev = _cancelled_gc.cmpxchg(NOT_CANCELLED, CANCELLABLE); 204 if (prev == CANCELLABLE || prev == NOT_CANCELLED) { 205 if (SuspendibleThreadSet::should_yield()) { 206 SuspendibleThreadSet::yield(); 207 } 208 209 // Back to CANCELLABLE. The thread that poked NOT_CANCELLED first gets 210 // to restore to CANCELLABLE. 211 if (prev == CANCELLABLE) { 212 _cancelled_gc.set(CANCELLABLE); 213 } 214 return false; 215 } else { 216 return true; 217 } 218 } 219 220 inline void ShenandoahHeap::clear_cancelled_gc() { 221 _cancelled_gc.set(CANCELLABLE); 222 _oom_evac_handler.clear(); 223 } 224 225 inline HeapWord* ShenandoahHeap::allocate_from_gclab(Thread* thread, size_t size) { 226 assert(UseTLAB, "TLABs should be enabled"); 227 228 PLAB* gclab = ShenandoahThreadLocalData::gclab(thread); 229 if (gclab == NULL) { 230 assert(!thread->is_Java_thread() && !thread->is_Worker_thread(), 231 "Performance: thread should have GCLAB: %s", thread->name()); 232 // No GCLABs in this thread, fallback to shared allocation 233 return NULL; 234 } 235 HeapWord* obj = gclab->allocate(size); 236 if (obj != NULL) { 237 return obj; 238 } 239 // Otherwise... 240 return allocate_from_gclab_slow(thread, size); 241 } 242 243 inline oop ShenandoahHeap::evacuate_object(oop p, Thread* thread) { 244 if (ShenandoahThreadLocalData::is_oom_during_evac(Thread::current())) { 245 // This thread went through the OOM during evac protocol and it is safe to return 246 // the forward pointer. It must not attempt to evacuate any more. 247 return ShenandoahBarrierSet::resolve_forwarded(p); 248 } 249 250 assert(ShenandoahThreadLocalData::is_evac_allowed(thread), "must be enclosed in oom-evac scope"); 251 assert(is_concurrent_traversal_in_progress() || !is_traversal_mode(), "Should not evacuate objects"); 252 253 size_t size = p->size(); 254 255 assert(!heap_region_containing(p)->is_humongous(), "never evacuate humongous objects"); 256 257 bool alloc_from_gclab = true; 258 HeapWord* copy = NULL; 259 260 #ifdef ASSERT 261 if (ShenandoahOOMDuringEvacALot && 262 (os::random() & 1) == 0) { // Simulate OOM every ~2nd slow-path call 263 copy = NULL; 264 } else { 265 #endif 266 if (UseTLAB) { 267 copy = allocate_from_gclab(thread, size); 268 } 269 if (copy == NULL) { 270 ShenandoahAllocRequest req = ShenandoahAllocRequest::for_shared_gc(size); 271 copy = allocate_memory(req); 272 alloc_from_gclab = false; 273 } 274 #ifdef ASSERT 275 } 276 #endif 277 278 if (copy == NULL) { 279 control_thread()->handle_alloc_failure_evac(size); 280 281 _oom_evac_handler.handle_out_of_memory_during_evacuation(); 282 283 return ShenandoahBarrierSet::resolve_forwarded(p); 284 } 285 286 // Copy the object: 287 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(p), copy, size); 288 289 // Try to install the new forwarding pointer. 290 oop copy_val = oop(copy); 291 oop result = ShenandoahForwarding::try_update_forwardee(p, copy_val); 292 if (result == copy_val) { 293 // Successfully evacuated. Our copy is now the public one! 294 shenandoah_assert_correct(NULL, copy_val); 295 return copy_val; 296 } else { 297 // Failed to evacuate. We need to deal with the object that is left behind. Since this 298 // new allocation is certainly after TAMS, it will be considered live in the next cycle. 299 // But if it happens to contain references to evacuated regions, those references would 300 // not get updated for this stale copy during this cycle, and we will crash while scanning 301 // it the next cycle. 302 // 303 // For GCLAB allocations, it is enough to rollback the allocation ptr. Either the next 304 // object will overwrite this stale copy, or the filler object on LAB retirement will 305 // do this. For non-GCLAB allocations, we have no way to retract the allocation, and 306 // have to explicitly overwrite the copy with the filler object. With that overwrite, 307 // we have to keep the fwdptr initialized and pointing to our (stale) copy. 308 if (alloc_from_gclab) { 309 ShenandoahThreadLocalData::gclab(thread)->undo_allocation(copy, size); 310 } else { 311 fill_with_object(copy, size); 312 shenandoah_assert_correct(NULL, copy_val); 313 } 314 shenandoah_assert_correct(NULL, result); 315 return result; 316 } 317 } 318 319 template<bool RESOLVE> 320 inline bool ShenandoahHeap::requires_marking(const void* entry) const { 321 oop obj = oop(entry); 322 if (RESOLVE) { 323 obj = ShenandoahBarrierSet::resolve_forwarded_not_null(obj); 324 } 325 return !_marking_context->is_marked(obj); 326 } 327 328 inline bool ShenandoahHeap::in_collection_set(oop p) const { 329 assert(collection_set() != NULL, "Sanity"); 330 assert(is_in(p), "should be in heap"); 331 return collection_set()->is_in(p); 332 } 333 334 inline bool ShenandoahHeap::in_collection_set_loc(void* p) const { 335 assert(collection_set() != NULL, "Sanity"); 336 assert(is_in(p), "should be in heap"); 337 return collection_set()->is_in((HeapWord*)p); 338 } 339 340 inline bool ShenandoahHeap::is_stable() const { 341 return _gc_state.is_clear(); 342 } 343 344 inline bool ShenandoahHeap::is_idle() const { 345 return _gc_state.is_unset(MARKING | EVACUATION | UPDATEREFS | TRAVERSAL); 346 } 347 348 inline bool ShenandoahHeap::is_concurrent_mark_in_progress() const { 349 return _gc_state.is_set(MARKING); 350 } 351 352 inline bool ShenandoahHeap::is_concurrent_traversal_in_progress() const { 353 return _gc_state.is_set(TRAVERSAL); 354 } 355 356 inline bool ShenandoahHeap::is_evacuation_in_progress() const { 357 return _gc_state.is_set(EVACUATION); 358 } 359 360 inline bool ShenandoahHeap::is_gc_in_progress_mask(uint mask) const { 361 return _gc_state.is_set(mask); 362 } 363 364 inline bool ShenandoahHeap::is_degenerated_gc_in_progress() const { 365 return _degenerated_gc_in_progress.is_set(); 366 } 367 368 inline bool ShenandoahHeap::is_full_gc_in_progress() const { 369 return _full_gc_in_progress.is_set(); 370 } 371 372 inline bool ShenandoahHeap::is_full_gc_move_in_progress() const { 373 return _full_gc_move_in_progress.is_set(); 374 } 375 376 inline bool ShenandoahHeap::is_update_refs_in_progress() const { 377 return _gc_state.is_set(UPDATEREFS); 378 } 379 380 inline bool ShenandoahHeap::is_stw_gc_in_progress() const { 381 return is_full_gc_in_progress() || is_degenerated_gc_in_progress(); 382 } 383 384 inline bool ShenandoahHeap::is_concurrent_root_in_progress() const { 385 return _concurrent_root_in_progress.is_set(); 386 } 387 388 template<class T> 389 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl) { 390 marked_object_iterate(region, cl, region->top()); 391 } 392 393 template<class T> 394 inline void ShenandoahHeap::marked_object_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* limit) { 395 assert(! region->is_humongous_continuation(), "no humongous continuation regions here"); 396 397 ShenandoahMarkingContext* const ctx = complete_marking_context(); 398 assert(ctx->is_complete(), "sanity"); 399 400 MarkBitMap* mark_bit_map = ctx->mark_bit_map(); 401 HeapWord* tams = ctx->top_at_mark_start(region); 402 403 size_t skip_bitmap_delta = 1; 404 HeapWord* start = region->bottom(); 405 HeapWord* end = MIN2(tams, region->end()); 406 407 // Step 1. Scan below the TAMS based on bitmap data. 408 HeapWord* limit_bitmap = MIN2(limit, tams); 409 410 // Try to scan the initial candidate. If the candidate is above the TAMS, it would 411 // fail the subsequent "< limit_bitmap" checks, and fall through to Step 2. 412 HeapWord* cb = mark_bit_map->get_next_marked_addr(start, end); 413 414 intx dist = ShenandoahMarkScanPrefetch; 415 if (dist > 0) { 416 // Batched scan that prefetches the oop data, anticipating the access to 417 // either header, oop field, or forwarding pointer. Not that we cannot 418 // touch anything in oop, while it still being prefetched to get enough 419 // time for prefetch to work. This is why we try to scan the bitmap linearly, 420 // disregarding the object size. However, since we know forwarding pointer 421 // preceeds the object, we can skip over it. Once we cannot trust the bitmap, 422 // there is no point for prefetching the oop contents, as oop->size() will 423 // touch it prematurely. 424 425 // No variable-length arrays in standard C++, have enough slots to fit 426 // the prefetch distance. 427 static const int SLOT_COUNT = 256; 428 guarantee(dist <= SLOT_COUNT, "adjust slot count"); 429 HeapWord* slots[SLOT_COUNT]; 430 431 int avail; 432 do { 433 avail = 0; 434 for (int c = 0; (c < dist) && (cb < limit_bitmap); c++) { 435 Prefetch::read(cb, oopDesc::mark_offset_in_bytes()); 436 slots[avail++] = cb; 437 cb += skip_bitmap_delta; 438 if (cb < limit_bitmap) { 439 cb = mark_bit_map->get_next_marked_addr(cb, limit_bitmap); 440 } 441 } 442 443 for (int c = 0; c < avail; c++) { 444 assert (slots[c] < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(tams)); 445 assert (slots[c] < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(slots[c]), p2i(limit)); 446 oop obj = oop(slots[c]); 447 assert(oopDesc::is_oop(obj), "sanity"); 448 assert(ctx->is_marked(obj), "object expected to be marked"); 449 cl->do_object(obj); 450 } 451 } while (avail > 0); 452 } else { 453 while (cb < limit_bitmap) { 454 assert (cb < tams, "only objects below TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(tams)); 455 assert (cb < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cb), p2i(limit)); 456 oop obj = oop(cb); 457 assert(oopDesc::is_oop(obj), "sanity"); 458 assert(ctx->is_marked(obj), "object expected to be marked"); 459 cl->do_object(obj); 460 cb += skip_bitmap_delta; 461 if (cb < limit_bitmap) { 462 cb = mark_bit_map->get_next_marked_addr(cb, limit_bitmap); 463 } 464 } 465 } 466 467 // Step 2. Accurate size-based traversal, happens past the TAMS. 468 // This restarts the scan at TAMS, which makes sure we traverse all objects, 469 // regardless of what happened at Step 1. 470 HeapWord* cs = tams; 471 while (cs < limit) { 472 assert (cs >= tams, "only objects past TAMS here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(tams)); 473 assert (cs < limit, "only objects below limit here: " PTR_FORMAT " (" PTR_FORMAT ")", p2i(cs), p2i(limit)); 474 oop obj = oop(cs); 475 assert(oopDesc::is_oop(obj), "sanity"); 476 assert(ctx->is_marked(obj), "object expected to be marked"); 477 int size = obj->size(); 478 cl->do_object(obj); 479 cs += size; 480 } 481 } 482 483 template <class T> 484 class ShenandoahObjectToOopClosure : public ObjectClosure { 485 T* _cl; 486 public: 487 ShenandoahObjectToOopClosure(T* cl) : _cl(cl) {} 488 489 void do_object(oop obj) { 490 obj->oop_iterate(_cl); 491 } 492 }; 493 494 template <class T> 495 class ShenandoahObjectToOopBoundedClosure : public ObjectClosure { 496 T* _cl; 497 MemRegion _bounds; 498 public: 499 ShenandoahObjectToOopBoundedClosure(T* cl, HeapWord* bottom, HeapWord* top) : 500 _cl(cl), _bounds(bottom, top) {} 501 502 void do_object(oop obj) { 503 obj->oop_iterate(_cl, _bounds); 504 } 505 }; 506 507 template<class T> 508 inline void ShenandoahHeap::marked_object_oop_iterate(ShenandoahHeapRegion* region, T* cl, HeapWord* top) { 509 if (region->is_humongous()) { 510 HeapWord* bottom = region->bottom(); 511 if (top > bottom) { 512 region = region->humongous_start_region(); 513 ShenandoahObjectToOopBoundedClosure<T> objs(cl, bottom, top); 514 marked_object_iterate(region, &objs); 515 } 516 } else { 517 ShenandoahObjectToOopClosure<T> objs(cl); 518 marked_object_iterate(region, &objs, top); 519 } 520 } 521 522 inline ShenandoahHeapRegion* const ShenandoahHeap::get_region(size_t region_idx) const { 523 if (region_idx < _num_regions) { 524 return _regions[region_idx]; 525 } else { 526 return NULL; 527 } 528 } 529 530 inline void ShenandoahHeap::mark_complete_marking_context() { 531 _marking_context->mark_complete(); 532 } 533 534 inline void ShenandoahHeap::mark_incomplete_marking_context() { 535 _marking_context->mark_incomplete(); 536 } 537 538 inline ShenandoahMarkingContext* ShenandoahHeap::complete_marking_context() const { 539 assert (_marking_context->is_complete()," sanity"); 540 return _marking_context; 541 } 542 543 inline ShenandoahMarkingContext* ShenandoahHeap::marking_context() const { 544 return _marking_context; 545 } 546 547 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHHEAP_INLINE_HPP