1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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  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).
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_GC_G1_HEAPREGION_INLINE_HPP
  26 #define SHARE_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 "oops/oop.inline.hpp"
  33 #include "runtime/atomic.hpp"
  34 #include "runtime/prefetch.inline.hpp"
  35 #include "utilities/align.hpp"
  36 #include "utilities/globalDefinitions.hpp"
  37 
  38 inline HeapWord* HeapRegion::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_object_aligned(obj) && is_object_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* HeapRegion::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(&_top, obj, new_top);
  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_object_aligned(obj) && is_object_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* HeapRegion::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* HeapRegion::allocate(size_t word_size) {
  90   size_t temp;
  91   return allocate(word_size, word_size, &temp);
  92 }
  93 
  94 inline HeapWord* HeapRegion::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* HeapRegion::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* HeapRegion::block_start(const void* p) {
 110   return _bot_part.block_start(p);
 111 }
 112 
 113 inline HeapWord* HeapRegion::block_start_const(const void* p) const {
 114   return _bot_part.block_start_const(p);
 115 }
 116 
 117 inline bool HeapRegion::is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const {
 118   HeapWord* addr = (HeapWord*) obj;
 119 
 120   assert(addr < top(), "must be");
 121   assert(!is_closed_archive(),
 122          "Closed archive regions should not have references into other regions");
 123   assert(!is_humongous(), "Humongous objects not handled here");
 124   bool obj_is_dead = is_obj_dead(obj, prev_bitmap);
 125 
 126   if (ClassUnloadingWithConcurrentMark && obj_is_dead) {
 127     assert(!block_is_obj(addr), "must be");
 128     *size = block_size_using_bitmap(addr, prev_bitmap);
 129   } else {
 130     assert(block_is_obj(addr), "must be");
 131     *size = obj->size();
 132   }
 133   return obj_is_dead;
 134 }
 135 
 136 inline bool HeapRegion::block_is_obj(const HeapWord* p) const {
 137   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 138 
 139   if (!this->is_in(p)) {
 140     assert(is_continues_humongous(), "This case can only happen for humongous regions");
 141     return (p == humongous_start_region()->bottom());
 142   }
 143   if (ClassUnloadingWithConcurrentMark) {
 144     return !g1h->is_obj_dead(oop(p), this);
 145   }
 146   return p < top();
 147 }
 148 
 149 inline size_t HeapRegion::block_size_using_bitmap(const HeapWord* addr, const G1CMBitMap* const prev_bitmap) const {
 150   assert(ClassUnloadingWithConcurrentMark,
 151          "All blocks should be objects if class unloading isn't used, so this method should not be called. "
 152          "HR: [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ") "
 153          "addr: " PTR_FORMAT,
 154          p2i(bottom()), p2i(top()), p2i(end()), p2i(addr));
 155 
 156   // Old regions' dead objects may have dead classes
 157   // We need to find the next live object using the bitmap
 158   HeapWord* next = prev_bitmap->get_next_marked_addr(addr, prev_top_at_mark_start());
 159 
 160   assert(next > addr, "must get the next live object");
 161   return pointer_delta(next, addr);
 162 }
 163 
 164 inline bool HeapRegion::is_obj_dead(const oop obj, const G1CMBitMap* const prev_bitmap) const {
 165   assert(is_in_reserved(obj), "Object " PTR_FORMAT " must be in region", p2i(obj));
 166   return !obj_allocated_since_prev_marking(obj) &&
 167          !prev_bitmap->is_marked((HeapWord*)obj) &&
 168          !is_open_archive();
 169 }
 170 
 171 inline size_t HeapRegion::block_size(const HeapWord *addr) const {
 172   if (addr == top()) {
 173     return pointer_delta(end(), addr);
 174   }
 175 
 176   if (block_is_obj(addr)) {
 177     return oop(addr)->size();
 178   }
 179 
 180   return block_size_using_bitmap(addr, G1CollectedHeap::heap()->concurrent_mark()->prev_mark_bitmap());
 181 }
 182 
 183 inline void HeapRegion::complete_compaction() {
 184   // Reset space and bot after compaction is complete if needed.
 185   reset_after_compaction();
 186   if (is_empty()) {
 187     reset_bot();
 188   }
 189 
 190   // After a compaction the mark bitmap is invalid, so we must
 191   // treat all objects as being inside the unmarked area.
 192   zero_marked_bytes();
 193   init_top_at_mark_start();
 194 
 195   // Clear unused heap memory in debug builds.
 196   if (ZapUnusedHeapArea) {
 197     mangle_unused_area();
 198   }
 199 }
 200 
 201 template<typename ApplyToMarkedClosure>
 202 inline void HeapRegion::apply_to_marked_objects(G1CMBitMap* bitmap, ApplyToMarkedClosure* closure) {
 203   HeapWord* limit = top();
 204   HeapWord* next_addr = bottom();
 205 
 206   while (next_addr < limit) {
 207     Prefetch::write(next_addr, PrefetchScanIntervalInBytes);
 208     // This explicit is_marked check is a way to avoid
 209     // some extra work done by get_next_marked_addr for
 210     // the case where next_addr is marked.
 211     if (bitmap->is_marked(next_addr)) {
 212       oop current = oop(next_addr);
 213       next_addr += closure->apply(current);
 214     } else {
 215       next_addr = bitmap->get_next_marked_addr(next_addr, limit);
 216     }
 217   }
 218 
 219   assert(next_addr == limit, "Should stop the scan at the limit.");
 220 }
 221 
 222 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t min_word_size,
 223                                                          size_t desired_word_size,
 224                                                          size_t* actual_word_size) {
 225   assert(is_young(), "we can only skip BOT updates on young regions");
 226   return par_allocate_impl(min_word_size, desired_word_size, actual_word_size);
 227 }
 228 
 229 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
 230   size_t temp;
 231   return allocate_no_bot_updates(word_size, word_size, &temp);
 232 }
 233 
 234 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t min_word_size,
 235                                                      size_t desired_word_size,
 236                                                      size_t* actual_word_size) {
 237   assert(is_young(), "we can only skip BOT updates on young regions");
 238   return allocate_impl(min_word_size, desired_word_size, actual_word_size);
 239 }
 240 
 241 inline void HeapRegion::note_start_of_marking() {
 242   _next_marked_bytes = 0;
 243   _next_top_at_mark_start = top();
 244 }
 245 
 246 inline void HeapRegion::note_end_of_marking() {
 247   _prev_top_at_mark_start = _next_top_at_mark_start;
 248   _next_top_at_mark_start = bottom();
 249   _prev_marked_bytes = _next_marked_bytes;
 250   _next_marked_bytes = 0;
 251 }
 252 
 253 inline bool HeapRegion::in_collection_set() const {
 254   return G1CollectedHeap::heap()->is_in_cset(this);
 255 }
 256 
 257 template <class Closure, bool is_gc_active>
 258 HeapWord* HeapRegion::do_oops_on_memregion_in_humongous(MemRegion mr,
 259                                                         Closure* cl,
 260                                                         G1CollectedHeap* g1h) {
 261   assert(is_humongous(), "precondition");
 262   HeapRegion* sr = humongous_start_region();
 263   oop obj = oop(sr->bottom());
 264 
 265   // If concurrent and klass_or_null is NULL, then space has been
 266   // allocated but the object has not yet been published by setting
 267   // the klass.  That can only happen if the card is stale.  However,
 268   // we've already set the card clean, so we must return failure,
 269   // since the allocating thread could have performed a write to the
 270   // card that might be missed otherwise.
 271   if (!is_gc_active && (obj->klass_or_null_acquire() == NULL)) {
 272     return NULL;
 273   }
 274 
 275   // We have a well-formed humongous object at the start of sr.
 276   // Only filler objects follow a humongous object in the containing
 277   // regions, and we can ignore those.  So only process the one
 278   // humongous object.
 279   if (g1h->is_obj_dead(obj, sr)) {
 280     // The object is dead. There can be no other object in this region, so return
 281     // the end of that region.
 282     return end();
 283   }
 284   if (obj->is_objArray() || (sr->bottom() < mr.start())) {
 285     // objArrays are always marked precisely, so limit processing
 286     // with mr.  Non-objArrays might be precisely marked, and since
 287     // it's humongous it's worthwhile avoiding full processing.
 288     // However, the card could be stale and only cover filler
 289     // objects.  That should be rare, so not worth checking for;
 290     // instead let it fall out from the bounded iteration.
 291     obj->oop_iterate(cl, mr);
 292     return mr.end();
 293   } else {
 294     // If obj is not an objArray and mr contains the start of the
 295     // obj, then this could be an imprecise mark, and we need to
 296     // process the entire object.
 297     int size = obj->oop_iterate_size(cl);
 298     // We have scanned to the end of the object, but since there can be no objects
 299     // after this humongous object in the region, we can return the end of the
 300     // region if it is greater.
 301     return MAX2((HeapWord*)obj + size, mr.end());
 302   }
 303 }
 304 
 305 template <bool is_gc_active, class Closure>
 306 HeapWord* HeapRegion::oops_on_memregion_seq_iterate_careful(MemRegion mr,
 307                                                        Closure* cl) {
 308   assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
 309   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 310 
 311   // Special handling for humongous regions.
 312   if (is_humongous()) {
 313     return do_oops_on_memregion_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
 314   }
 315   assert(is_old() || is_archive(), "Wrongly trying to iterate over region %u type %s", _hrm_index, get_type_str());
 316 
 317   // Because mr has been trimmed to what's been allocated in this
 318   // region, the parts of the heap that are examined here are always
 319   // parsable; there's no need to use klass_or_null to detect
 320   // in-progress allocation.
 321 
 322   // Cache the boundaries of the memory region in some const locals
 323   HeapWord* const start = mr.start();
 324   HeapWord* const end = mr.end();
 325 
 326   // Find the obj that extends onto mr.start().
 327   // Update BOT as needed while finding start of (possibly dead)
 328   // object containing the start of the region.
 329   HeapWord* cur = block_start(start);
 330 
 331 #ifdef ASSERT
 332   {
 333     assert(cur <= start,
 334            "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
 335     HeapWord* next = cur + block_size(cur);
 336     assert(start < next,
 337            "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
 338   }
 339 #endif
 340 
 341   const G1CMBitMap* const bitmap = g1h->concurrent_mark()->prev_mark_bitmap();
 342   while (true) {
 343     oop obj = oop(cur);
 344     assert(oopDesc::is_oop(obj, true), "Not an oop at " PTR_FORMAT, p2i(cur));
 345     assert(obj->klass_or_null() != NULL,
 346            "Unparsable heap at " PTR_FORMAT, p2i(cur));
 347 
 348     size_t size;
 349     bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);
 350     bool is_precise = false;
 351 
 352     cur += size;
 353     if (!is_dead) {
 354       // Process live object's references.
 355 
 356       // Non-objArrays are usually marked imprecise at the object
 357       // start, in which case we need to iterate over them in full.
 358       // objArrays are precisely marked, but can still be iterated
 359       // over in full if completely covered.
 360       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
 361         obj->oop_iterate(cl);
 362       } else {
 363         obj->oop_iterate(cl, mr);
 364         is_precise = true;
 365       }
 366     }
 367     if (cur >= end) {
 368       return is_precise ? end : cur;
 369     }
 370   }
 371 }
 372 
 373 #endif // SHARE_GC_G1_HEAPREGION_INLINE_HPP
--- EOF ---