1 /* 2 * Copyright (c) 2015, 2022, Red Hat, Inc. All rights reserved. 3 * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26 #ifndef SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP 27 #define SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP 28 29 #include "gc/shenandoah/shenandoahMark.hpp" 30 31 #include "gc/shared/continuationGCSupport.inline.hpp" 32 #include "gc/shenandoah/shenandoahAgeCensus.hpp" 33 #include "gc/shenandoah/shenandoahAsserts.hpp" 34 #include "gc/shenandoah/shenandoahBarrierSet.inline.hpp" 35 #include "gc/shenandoah/shenandoahHeap.inline.hpp" 36 #include "gc/shenandoah/shenandoahMarkingContext.inline.hpp" 37 #include "gc/shenandoah/shenandoahOldGeneration.hpp" 38 #include "gc/shenandoah/shenandoahOopClosures.inline.hpp" 39 #include "gc/shenandoah/shenandoahScanRemembered.inline.hpp" 40 #include "gc/shenandoah/shenandoahStringDedup.inline.hpp" 41 #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp" 42 #include "gc/shenandoah/shenandoahUtils.hpp" 43 #include "memory/iterator.inline.hpp" 44 #include "oops/compressedOops.inline.hpp" 45 #include "oops/oop.inline.hpp" 46 #include "runtime/prefetch.inline.hpp" 47 #include "utilities/devirtualizer.inline.hpp" 48 #include "utilities/powerOfTwo.hpp" 49 50 template <StringDedupMode STRING_DEDUP> 51 void ShenandoahMark::dedup_string(oop obj, StringDedup::Requests* const req) { 52 if (STRING_DEDUP == ENQUEUE_DEDUP) { 53 if (ShenandoahStringDedup::is_candidate(obj)) { 54 req->add(obj); 55 } 56 } else if (STRING_DEDUP == ALWAYS_DEDUP) { 57 if (ShenandoahStringDedup::is_string_candidate(obj) && 58 !ShenandoahStringDedup::dedup_requested(obj)) { 59 req->add(obj); 60 } 61 } 62 } 63 64 template <class T, ShenandoahGenerationType GENERATION, StringDedupMode STRING_DEDUP> 65 void ShenandoahMark::do_task(ShenandoahObjToScanQueue* q, T* cl, ShenandoahLiveData* live_data, StringDedup::Requests* const req, ShenandoahMarkTask* task, uint worker_id) { 66 oop obj = task->obj(); 67 68 // TODO: This will push array chunks into the mark queue with no regard for 69 // generations. I don't think it will break anything, but the young generation 70 // scan might end up processing some old generation array chunks. 71 72 shenandoah_assert_not_forwarded(nullptr, obj); 73 shenandoah_assert_marked(nullptr, obj); 74 shenandoah_assert_not_in_cset_except(nullptr, obj, ShenandoahHeap::heap()->cancelled_gc()); 75 76 // Are we in weak subgraph scan? 77 bool weak = task->is_weak(); 78 cl->set_weak(weak); 79 80 if (task->is_not_chunked()) { 81 if (obj->is_instance()) { 82 // Case 1: Normal oop, process as usual. 83 if (ContinuationGCSupport::relativize_stack_chunk(obj)) { 84 // Loom doesn't support mixing of weak marking and strong marking of 85 // stack chunks. 86 cl->set_weak(false); 87 } 88 89 obj->oop_iterate(cl); 90 dedup_string<STRING_DEDUP>(obj, req); 91 } else if (obj->is_objArray()) { 92 // Case 2: Object array instance and no chunk is set. Must be the first 93 // time we visit it, start the chunked processing. 94 do_chunked_array_start<T>(q, cl, obj, weak); 95 } else { 96 // Case 3: Primitive array. Do nothing, no oops there. We use the same 97 // performance tweak TypeArrayKlass::oop_oop_iterate_impl is using: 98 // We skip iterating over the klass pointer since we know that 99 // Universe::TypeArrayKlass never moves. 100 assert (obj->is_typeArray(), "should be type array"); 101 } 102 // Count liveness the last: push the outstanding work to the queues first 103 // Avoid double-counting objects that are visited twice due to upgrade 104 // from final- to strong mark. 105 if (task->count_liveness()) { 106 count_liveness<GENERATION>(live_data, obj, worker_id); 107 } 108 } else { 109 // Case 4: Array chunk, has sensible chunk id. Process it. 110 do_chunked_array<T>(q, cl, obj, task->chunk(), task->pow(), weak); 111 } 112 } 113 114 template <ShenandoahGenerationType GENERATION> 115 inline void ShenandoahMark::count_liveness(ShenandoahLiveData* live_data, oop obj, uint worker_id) { 116 const ShenandoahHeap* const heap = ShenandoahHeap::heap(); 117 const size_t region_idx = heap->heap_region_index_containing(obj); 118 ShenandoahHeapRegion* const region = heap->get_region(region_idx); 119 const size_t size = obj->size(); 120 121 // Age census for objects in the young generation 122 if (GENERATION == YOUNG || (GENERATION == GLOBAL && region->is_young())) { 123 assert(heap->mode()->is_generational(), "Only if generational"); 124 if (ShenandoahGenerationalAdaptiveTenuring && !ShenandoahGenerationalCensusAtEvac) { 125 assert(region->is_young(), "Only for young objects"); 126 uint age = ShenandoahHeap::get_object_age(obj); 127 ShenandoahAgeCensus* const census = ShenandoahGenerationalHeap::heap()->age_census(); 128 CENSUS_NOISE(census->add(age, region->age(), region->youth(), size, worker_id);) 129 NO_CENSUS_NOISE(census->add(age, region->age(), size, worker_id);) 130 } 131 } 132 133 if (!region->is_humongous_start()) { 134 assert(!region->is_humongous(), "Cannot have continuations here"); 135 assert(region->is_affiliated(), "Do not count live data within Free Regular Region " SIZE_FORMAT, region_idx); 136 ShenandoahLiveData cur = live_data[region_idx]; 137 size_t new_val = size + cur; 138 if (new_val >= SHENANDOAH_LIVEDATA_MAX) { 139 // overflow, flush to region data 140 region->increase_live_data_gc_words(new_val); 141 live_data[region_idx] = 0; 142 } else { 143 // still good, remember in locals 144 live_data[region_idx] = (ShenandoahLiveData) new_val; 145 } 146 } else { 147 shenandoah_assert_in_correct_region(nullptr, obj); 148 size_t num_regions = ShenandoahHeapRegion::required_regions(size * HeapWordSize); 149 150 assert(region->is_affiliated(), "Do not count live data within FREE Humongous Start Region " SIZE_FORMAT, region_idx); 151 for (size_t i = region_idx; i < region_idx + num_regions; i++) { 152 ShenandoahHeapRegion* chain_reg = heap->get_region(i); 153 assert(chain_reg->is_humongous(), "Expecting a humongous region"); 154 assert(chain_reg->is_affiliated(), "Do not count live data within FREE Humongous Continuation Region " SIZE_FORMAT, i); 155 chain_reg->increase_live_data_gc_words(chain_reg->used() >> LogHeapWordSize); 156 } 157 } 158 } 159 160 template <class T> 161 inline void ShenandoahMark::do_chunked_array_start(ShenandoahObjToScanQueue* q, T* cl, oop obj, bool weak) { 162 assert(obj->is_objArray(), "expect object array"); 163 objArrayOop array = objArrayOop(obj); 164 int len = array->length(); 165 166 // Mark objArray klass metadata 167 if (Devirtualizer::do_metadata(cl)) { 168 Devirtualizer::do_klass(cl, array->klass()); 169 } 170 171 if (len <= (int) ObjArrayMarkingStride*2) { 172 // A few slices only, process directly 173 array->oop_iterate_range(cl, 0, len); 174 } else { 175 int bits = log2i_graceful(len); 176 // Compensate for non-power-of-two arrays, cover the array in excess: 177 if (len != (1 << bits)) bits++; 178 179 // Only allow full chunks on the queue. This frees do_chunked_array() from checking from/to 180 // boundaries against array->length(), touching the array header on every chunk. 181 // 182 // To do this, we cut the prefix in full-sized chunks, and submit them on the queue. 183 // If the array is not divided in chunk sizes, then there would be an irregular tail, 184 // which we will process separately. 185 186 int last_idx = 0; 187 188 int chunk = 1; 189 int pow = bits; 190 191 // Handle overflow 192 if (pow >= 31) { 193 assert (pow == 31, "sanity"); 194 pow--; 195 chunk = 2; 196 last_idx = (1 << pow); 197 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, 1, pow)); 198 assert(pushed, "overflow queue should always succeed pushing"); 199 } 200 201 // Split out tasks, as suggested in ShenandoahMarkTask docs. Record the last 202 // successful right boundary to figure out the irregular tail. 203 while ((1 << pow) > (int)ObjArrayMarkingStride && 204 (chunk*2 < ShenandoahMarkTask::chunk_size())) { 205 pow--; 206 int left_chunk = chunk*2 - 1; 207 int right_chunk = chunk*2; 208 int left_chunk_end = left_chunk * (1 << pow); 209 if (left_chunk_end < len) { 210 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, left_chunk, pow)); 211 assert(pushed, "overflow queue should always succeed pushing"); 212 chunk = right_chunk; 213 last_idx = left_chunk_end; 214 } else { 215 chunk = left_chunk; 216 } 217 } 218 219 // Process the irregular tail, if present 220 int from = last_idx; 221 if (from < len) { 222 array->oop_iterate_range(cl, from, len); 223 } 224 } 225 } 226 227 template <class T> 228 inline void ShenandoahMark::do_chunked_array(ShenandoahObjToScanQueue* q, T* cl, oop obj, int chunk, int pow, bool weak) { 229 assert(obj->is_objArray(), "expect object array"); 230 objArrayOop array = objArrayOop(obj); 231 232 assert (ObjArrayMarkingStride > 0, "sanity"); 233 234 // Split out tasks, as suggested in ShenandoahMarkTask docs. Avoid pushing tasks that 235 // are known to start beyond the array. 236 while ((1 << pow) > (int)ObjArrayMarkingStride && (chunk*2 < ShenandoahMarkTask::chunk_size())) { 237 pow--; 238 chunk *= 2; 239 bool pushed = q->push(ShenandoahMarkTask(array, true, weak, chunk - 1, pow)); 240 assert(pushed, "overflow queue should always succeed pushing"); 241 } 242 243 int chunk_size = 1 << pow; 244 245 int from = (chunk - 1) * chunk_size; 246 int to = chunk * chunk_size; 247 248 #ifdef ASSERT 249 int len = array->length(); 250 assert (0 <= from && from < len, "from is sane: %d/%d", from, len); 251 assert (0 < to && to <= len, "to is sane: %d/%d", to, len); 252 #endif 253 254 array->oop_iterate_range(cl, from, to); 255 } 256 257 template <ShenandoahGenerationType GENERATION> 258 class ShenandoahSATBBufferClosure : public SATBBufferClosure { 259 private: 260 ShenandoahObjToScanQueue* _queue; 261 ShenandoahObjToScanQueue* _old_queue; 262 ShenandoahHeap* _heap; 263 ShenandoahMarkingContext* const _mark_context; 264 public: 265 ShenandoahSATBBufferClosure(ShenandoahObjToScanQueue* q, ShenandoahObjToScanQueue* old_q) : 266 _queue(q), 267 _old_queue(old_q), 268 _heap(ShenandoahHeap::heap()), 269 _mark_context(_heap->marking_context()) 270 { 271 } 272 273 void do_buffer(void **buffer, size_t size) { 274 assert(size == 0 || !_heap->has_forwarded_objects() || _heap->is_concurrent_old_mark_in_progress(), "Forwarded objects are not expected here"); 275 for (size_t i = 0; i < size; ++i) { 276 oop *p = (oop *) &buffer[i]; 277 ShenandoahMark::mark_through_ref<oop, GENERATION>(p, _queue, _old_queue, _mark_context, false); 278 } 279 } 280 }; 281 282 template<ShenandoahGenerationType GENERATION> 283 bool ShenandoahMark::in_generation(ShenandoahHeap* const heap, oop obj) { 284 // Each in-line expansion of in_generation() resolves GENERATION at compile time. 285 if (GENERATION == YOUNG) { 286 return heap->is_in_young(obj); 287 } 288 289 if (GENERATION == OLD) { 290 return heap->is_in_old(obj); 291 } 292 293 assert((GENERATION == GLOBAL || GENERATION == NON_GEN), "Unexpected generation type"); 294 assert(heap->is_in(obj), "Object must be in heap"); 295 return true; 296 } 297 298 template<class T, ShenandoahGenerationType GENERATION> 299 inline void ShenandoahMark::mark_through_ref(T *p, ShenandoahObjToScanQueue* q, ShenandoahObjToScanQueue* old_q, ShenandoahMarkingContext* const mark_context, bool weak) { 300 // Note: This is a very hot code path, so the code should be conditional on GENERATION template 301 // parameter where possible, in order to generate the most efficient code. 302 303 T o = RawAccess<>::oop_load(p); 304 if (!CompressedOops::is_null(o)) { 305 oop obj = CompressedOops::decode_not_null(o); 306 307 ShenandoahGenerationalHeap* heap = ShenandoahGenerationalHeap::heap(); 308 shenandoah_assert_not_forwarded(p, obj); 309 shenandoah_assert_not_in_cset_except(p, obj, heap->cancelled_gc()); 310 if (in_generation<GENERATION>(heap, obj)) { 311 mark_ref(q, mark_context, weak, obj); 312 shenandoah_assert_marked(p, obj); 313 // TODO: As implemented herein, GLOBAL collections reconstruct the card table during GLOBAL concurrent 314 // marking. Note that the card table is cleaned at init_mark time so it needs to be reconstructed to support 315 // future young-gen collections. It might be better to reconstruct card table in a different phase. We could 316 // either mark all live memory as dirty, or could use the GLOBAL update-refs scanning of pointers to determine 317 // precisely which cards to flag as dirty. 318 if (GENERATION == YOUNG && heap->is_in_old(p)) { 319 // Mark card as dirty because remembered set scanning still finds interesting pointer. 320 heap->old_generation()->mark_card_as_dirty((HeapWord*)p); 321 } else if (GENERATION == GLOBAL && heap->is_in_old(p) && heap->is_in_young(obj)) { 322 // Mark card as dirty because GLOBAL marking finds interesting pointer. 323 heap->old_generation()->mark_card_as_dirty((HeapWord*)p); 324 } 325 } else if (old_q != nullptr) { 326 // Young mark, bootstrapping old_q or concurrent with old_q marking. 327 mark_ref(old_q, mark_context, weak, obj); 328 shenandoah_assert_marked(p, obj); 329 } else if (GENERATION == OLD) { 330 // Old mark, found a young pointer. 331 // TODO: Rethink this: may be redundant with dirtying of cards identified during young-gen remembered set scanning 332 // and by mutator write barriers. 333 if (heap->is_in(p)) { 334 assert(heap->is_in_young(obj), "Expected young object."); 335 // TODO: This assert _should not_ pop, but it does. We need to figure out why. 336 // assert(heap->old_generation()->card_scan()->is_card_dirty((HeapWord*)p), "Card should already be marked."); 337 heap->old_generation()->mark_card_as_dirty(p); 338 } 339 } 340 } 341 } 342 343 template<> 344 inline void ShenandoahMark::mark_through_ref<oop, ShenandoahGenerationType::NON_GEN>(oop *p, ShenandoahObjToScanQueue* q, ShenandoahObjToScanQueue* old_q, ShenandoahMarkingContext* const mark_context, bool weak) { 345 mark_non_generational_ref(p, q, mark_context, weak); 346 } 347 348 template<> 349 inline void ShenandoahMark::mark_through_ref<narrowOop, ShenandoahGenerationType::NON_GEN>(narrowOop *p, ShenandoahObjToScanQueue* q, ShenandoahObjToScanQueue* old_q, ShenandoahMarkingContext* const mark_context, bool weak) { 350 mark_non_generational_ref(p, q, mark_context, weak); 351 } 352 353 template<class T> 354 inline void ShenandoahMark::mark_non_generational_ref(T* p, ShenandoahObjToScanQueue* q, 355 ShenandoahMarkingContext* const mark_context, bool weak) { 356 oop o = RawAccess<>::oop_load(p); 357 if (!CompressedOops::is_null(o)) { 358 oop obj = CompressedOops::decode_not_null(o); 359 360 shenandoah_assert_not_forwarded(p, obj); 361 shenandoah_assert_not_in_cset_except(p, obj, ShenandoahHeap::heap()->cancelled_gc()); 362 363 mark_ref(q, mark_context, weak, obj); 364 365 shenandoah_assert_marked(p, obj); 366 } 367 } 368 369 inline void ShenandoahMark::mark_ref(ShenandoahObjToScanQueue* q, 370 ShenandoahMarkingContext* const mark_context, 371 bool weak, oop obj) { 372 bool skip_live = false; 373 bool marked; 374 if (weak) { 375 marked = mark_context->mark_weak(obj); 376 } else { 377 marked = mark_context->mark_strong(obj, /* was_upgraded = */ skip_live); 378 } 379 if (marked) { 380 bool pushed = q->push(ShenandoahMarkTask(obj, skip_live, weak)); 381 assert(pushed, "overflow queue should always succeed pushing"); 382 } 383 } 384 385 ShenandoahObjToScanQueueSet* ShenandoahMark::task_queues() const { 386 return _task_queues; 387 } 388 389 ShenandoahObjToScanQueue* ShenandoahMark::get_queue(uint index) const { 390 return _task_queues->queue(index); 391 } 392 393 ShenandoahObjToScanQueue* ShenandoahMark::get_old_queue(uint index) const { 394 if (_old_gen_task_queues != nullptr) { 395 return _old_gen_task_queues->queue(index); 396 } 397 return nullptr; 398 } 399 400 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHMARK_INLINE_HPP