1 /*
   2  * Copyright (c) 2001, 2018, 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_VM_GC_G1_HEAPREGION_INLINE_HPP
  26 #define SHARE_VM_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 "utilities/align.hpp"
  37 
  38 inline HeapWord* G1ContiguousSpace::allocate_impl(size_t min_word_size,
  39                                                   size_t desired_word_size,
  40                                                   size_t* actual_size) {
  41   HeapWord* obj = top();
  42   size_t available = pointer_delta(end(), obj);
  43   size_t want_to_allocate = MIN2(available, desired_word_size);
  44   if (want_to_allocate >= min_word_size) {
  45     HeapWord* new_top = obj + want_to_allocate;
  46     set_top(new_top);
  47     assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
  48     *actual_size = want_to_allocate;
  49     return obj;
  50   } else {
  51     return NULL;
  52   }
  53 }
  54 
  55 inline HeapWord* G1ContiguousSpace::par_allocate_impl(size_t min_word_size,
  56                                                       size_t desired_word_size,
  57                                                       size_t* actual_size) {
  58   do {
  59     HeapWord* obj = top();
  60     size_t available = pointer_delta(end(), obj);
  61     size_t want_to_allocate = MIN2(available, desired_word_size);
  62     if (want_to_allocate >= min_word_size) {
  63       HeapWord* new_top = obj + want_to_allocate;
  64       HeapWord* result = Atomic::cmpxchg(new_top, top_addr(), obj);
  65       // result can be one of two:
  66       //  the old top value: the exchange succeeded
  67       //  otherwise: the new value of the top is returned.
  68       if (result == obj) {
  69         assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
  70         *actual_size = want_to_allocate;
  71         return obj;
  72       }
  73     } else {
  74       return NULL;
  75     }
  76   } while (true);
  77 }
  78 
  79 inline HeapWord* G1ContiguousSpace::allocate(size_t min_word_size,
  80                                              size_t desired_word_size,
  81                                              size_t* actual_size) {
  82   HeapWord* res = allocate_impl(min_word_size, desired_word_size, actual_size);
  83   if (res != NULL) {
  84     _bot_part.alloc_block(res, *actual_size);
  85   }
  86   return res;
  87 }
  88 
  89 inline HeapWord* G1ContiguousSpace::allocate(size_t word_size) {
  90   size_t temp;
  91   return allocate(word_size, word_size, &temp);
  92 }
  93 
  94 inline HeapWord* G1ContiguousSpace::par_allocate(size_t word_size) {
  95   size_t temp;
  96   return par_allocate(word_size, word_size, &temp);
  97 }
  98 
  99 // Because of the requirement of keeping "_offsets" up to date with the
 100 // allocations, we sequentialize these with a lock.  Therefore, best if
 101 // this is used for larger LAB allocations only.
 102 inline HeapWord* G1ContiguousSpace::par_allocate(size_t min_word_size,
 103                                                  size_t desired_word_size,
 104                                                  size_t* actual_size) {
 105   MutexLocker x(&_par_alloc_lock);
 106   return allocate(min_word_size, desired_word_size, actual_size);
 107 }
 108 
 109 inline HeapWord* G1ContiguousSpace::block_start(const void* p) {
 110   return _bot_part.block_start(p);
 111 }
 112 
 113 inline HeapWord*
 114 G1ContiguousSpace::block_start_const(const void* p) const {
 115   return _bot_part.block_start_const(p);
 116 }
 117 
 118 inline bool HeapRegion::is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const {
 119   HeapWord* addr = (HeapWord*) obj;
 120 
 121   assert(addr < top(), "must be");
 122   assert(!is_closed_archive(),
 123          "Closed archive regions should not have references into other regions");
 124   assert(!is_humongous(), "Humongous objects not handled here");
 125   bool obj_is_dead = is_obj_dead(obj, prev_bitmap);
 126 
 127   if (ClassUnloadingWithConcurrentMark && obj_is_dead) {
 128     assert(!block_is_obj(addr), "must be");
 129     *size = block_size_using_bitmap(addr, prev_bitmap);
 130   } else {
 131     assert(block_is_obj(addr), "must be");
 132     *size = obj->size();
 133   }
 134   return obj_is_dead;
 135 }
 136 
 137 inline bool
 138 HeapRegion::block_is_obj(const HeapWord* p) const {
 139   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 140 
 141   if (!this->is_in(p)) {
 142     assert(is_continues_humongous(), "This case can only happen for humongous regions");
 143     return (p == humongous_start_region()->bottom());
 144   }
 145   if (ClassUnloadingWithConcurrentMark) {
 146     return !g1h->is_obj_dead(oop(p), this);
 147   }
 148   return p < top();
 149 }
 150 
 151 inline size_t HeapRegion::block_size_using_bitmap(const HeapWord* addr, const G1CMBitMap* const prev_bitmap) const {
 152   assert(ClassUnloadingWithConcurrentMark,
 153          "All blocks should be objects if class unloading isn't used, so this method should not be called. "
 154          "HR: [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ") "
 155          "addr: " PTR_FORMAT,
 156          p2i(bottom()), p2i(top()), p2i(end()), p2i(addr));
 157 
 158   // Old regions' dead objects may have dead classes
 159   // We need to find the next live object using the bitmap
 160   HeapWord* next = prev_bitmap->get_next_marked_addr(addr, prev_top_at_mark_start());
 161 
 162   assert(next > addr, "must get the next live object");
 163   return pointer_delta(next, addr);
 164 }
 165 
 166 inline bool HeapRegion::is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const {
 167   assert(is_in_reserved(obj), "Object " PTR_FORMAT " must be in region", p2i(obj));
 168   return !obj_allocated_since_prev_marking(obj) &&
 169          !prev_bitmap->is_marked((HeapWord*)obj) &&
 170          !is_open_archive();
 171 }
 172 
 173 inline size_t HeapRegion::block_size(const HeapWord *addr) const {
 174   if (addr == top()) {
 175     return pointer_delta(end(), addr);
 176   }
 177 
 178   if (block_is_obj(addr)) {
 179     return oop(addr)->size();
 180   }
 181 
 182   return block_size_using_bitmap(addr, G1CollectedHeap::heap()->concurrent_mark()->prev_mark_bitmap());
 183 }
 184 
 185 inline void HeapRegion::complete_compaction() {
 186   // Reset space and bot after compaction is complete if needed.
 187   reset_after_compaction();
 188   if (used_region().is_empty()) {
 189     reset_bot();
 190   }
 191 
 192   // After a compaction the mark bitmap is invalid, so we must
 193   // treat all objects as being inside the unmarked area.
 194   zero_marked_bytes();
 195   init_top_at_mark_start();
 196 
 197   // Clear unused heap memory in debug builds.
 198   if (ZapUnusedHeapArea) {
 199     mangle_unused_area();
 200   }
 201 }
 202 
 203 template<typename ApplyToMarkedClosure>
 204 inline void HeapRegion::apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure) {
 205   HeapWord* limit = scan_limit();
 206   HeapWord* next_addr = bottom();
 207 
 208   while (next_addr < limit) {
 209     Prefetch::write(next_addr, PrefetchScanIntervalInBytes);
 210     // This explicit is_marked check is a way to avoid
 211     // some extra work done by get_next_marked_addr for
 212     // the case where next_addr is marked.
 213     if (bitmap->is_marked(next_addr)) {
 214       oop current = oop(next_addr);
 215       next_addr += closure->apply(current);
 216     } else {
 217       next_addr = bitmap->get_next_marked_addr(next_addr, limit);
 218     }
 219   }
 220 
 221   assert(next_addr == limit, "Should stop the scan at the limit.");
 222 }
 223 
 224 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t min_word_size,
 225                                                          size_t desired_word_size,
 226                                                          size_t* actual_word_size) {
 227   assert(is_young(), "we can only skip BOT updates on young regions");
 228   return par_allocate_impl(min_word_size, desired_word_size, actual_word_size);
 229 }
 230 
 231 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
 232   size_t temp;
 233   return allocate_no_bot_updates(word_size, word_size, &temp);
 234 }
 235 
 236 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t min_word_size,
 237                                                      size_t desired_word_size,
 238                                                      size_t* actual_word_size) {
 239   assert(is_young(), "we can only skip BOT updates on young regions");
 240   return allocate_impl(min_word_size, desired_word_size, actual_word_size);
 241 }
 242 
 243 inline void HeapRegion::note_start_of_marking() {
 244   _next_marked_bytes = 0;
 245   _next_top_at_mark_start = top();
 246 }
 247 
 248 inline void HeapRegion::note_end_of_marking() {
 249   _prev_top_at_mark_start = _next_top_at_mark_start;
 250   _next_top_at_mark_start = bottom();
 251   _prev_marked_bytes = _next_marked_bytes;
 252   _next_marked_bytes = 0;
 253 }
 254 
 255 inline bool HeapRegion::in_collection_set() const {
 256   return G1CollectedHeap::heap()->is_in_cset(this);
 257 }
 258 
 259 template <class Closure, bool is_gc_active>
 260 bool HeapRegion::do_oops_on_card_in_humongous(MemRegion mr,
 261                                               Closure* cl,
 262                                               G1CollectedHeap* g1h) {
 263   assert(is_humongous(), "precondition");
 264   HeapRegion* sr = humongous_start_region();
 265   oop obj = oop(sr->bottom());
 266 
 267   // If concurrent and klass_or_null is NULL, then space has been
 268   // allocated but the object has not yet been published by setting
 269   // the klass.  That can only happen if the card is stale.  However,
 270   // we've already set the card clean, so we must return failure,
 271   // since the allocating thread could have performed a write to the
 272   // card that might be missed otherwise.
 273   if (!is_gc_active && (obj->klass_or_null_acquire() == NULL)) {
 274     return false;
 275   }
 276 
 277   // We have a well-formed humongous object at the start of sr.
 278   // Only filler objects follow a humongous object in the containing
 279   // regions, and we can ignore those.  So only process the one
 280   // humongous object.
 281   if (!g1h->is_obj_dead(obj, sr)) {
 282     if (obj->is_objArray() || (sr->bottom() < mr.start())) {
 283       // objArrays are always marked precisely, so limit processing
 284       // with mr.  Non-objArrays might be precisely marked, and since
 285       // it's humongous it's worthwhile avoiding full processing.
 286       // However, the card could be stale and only cover filler
 287       // objects.  That should be rare, so not worth checking for;
 288       // instead let it fall out from the bounded iteration.
 289       obj->oop_iterate(cl, mr);
 290     } else {
 291       // If obj is not an objArray and mr contains the start of the
 292       // obj, then this could be an imprecise mark, and we need to
 293       // process the entire object.
 294       obj->oop_iterate(cl);
 295     }
 296   }
 297   return true;
 298 }
 299 
 300 template <bool is_gc_active, class Closure>
 301 bool HeapRegion::oops_on_card_seq_iterate_careful(MemRegion mr,
 302                                                   Closure* cl) {
 303   assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
 304   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 305 
 306   // Special handling for humongous regions.
 307   if (is_humongous()) {
 308     return do_oops_on_card_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
 309   }
 310   assert(is_old() || is_archive(), "Wrongly trying to iterate over region %u type %s", _hrm_index, get_type_str());
 311 
 312   // Because mr has been trimmed to what's been allocated in this
 313   // region, the parts of the heap that are examined here are always
 314   // parsable; there's no need to use klass_or_null to detect
 315   // in-progress allocation.
 316 
 317   // Cache the boundaries of the memory region in some const locals
 318   HeapWord* const start = mr.start();
 319   HeapWord* const end = mr.end();
 320 
 321   // Find the obj that extends onto mr.start().
 322   // Update BOT as needed while finding start of (possibly dead)
 323   // object containing the start of the region.
 324   HeapWord* cur = block_start(start);
 325 
 326 #ifdef ASSERT
 327   {
 328     assert(cur <= start,
 329            "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
 330     HeapWord* next = cur + block_size(cur);
 331     assert(start < next,
 332            "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
 333   }
 334 #endif
 335 
 336   const G1CMBitMap* const bitmap = g1h->concurrent_mark()->prev_mark_bitmap();
 337   do {
 338     oop obj = oop(cur);
 339     assert(oopDesc::is_oop(obj, true), "Not an oop at " PTR_FORMAT, p2i(cur));
 340     assert(obj->klass_or_null() != NULL,
 341            "Unparsable heap at " PTR_FORMAT, p2i(cur));
 342 
 343     size_t size;
 344     bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);
 345 
 346     cur += size;
 347     if (!is_dead) {
 348       // Process live object's references.
 349 
 350       // Non-objArrays are usually marked imprecise at the object
 351       // start, in which case we need to iterate over them in full.
 352       // objArrays are precisely marked, but can still be iterated
 353       // over in full if completely covered.
 354       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
 355         obj->oop_iterate(cl);
 356       } else {
 357         obj->oop_iterate(cl, mr);
 358       }
 359     }
 360   } while (cur < end);
 361 
 362   return true;
 363 }
 364 
 365 #endif // SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP