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