1 /*
   2  * Copyright (c) 2001, 2017, 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/heapRegion.hpp"
  31 #include "gc/shared/space.hpp"
  32 #include "oops/oop.inline.hpp"
  33 #include "runtime/atomic.hpp"
  34 #include "utilities/align.hpp"
  35 
  36 inline HeapWord* G1ContiguousSpace::allocate_impl(size_t min_word_size,
  37                                                   size_t desired_word_size,
  38                                                   size_t* actual_size) {
  39   HeapWord* obj = top();
  40   size_t available = pointer_delta(end(), obj);
  41   size_t want_to_allocate = MIN2(available, desired_word_size);
  42   if (want_to_allocate >= min_word_size) {
  43     HeapWord* new_top = obj + want_to_allocate;
  44     set_top(new_top);
  45     assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
  46     *actual_size = want_to_allocate;
  47     return obj;
  48   } else {
  49     return NULL;
  50   }
  51 }
  52 
  53 inline HeapWord* G1ContiguousSpace::par_allocate_impl(size_t min_word_size,
  54                                                       size_t desired_word_size,
  55                                                       size_t* actual_size) {
  56   do {
  57     HeapWord* obj = top();
  58     size_t available = pointer_delta(end(), obj);
  59     size_t want_to_allocate = MIN2(available, desired_word_size);
  60     if (want_to_allocate >= min_word_size) {
  61       HeapWord* new_top = obj + want_to_allocate;
  62       HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
  63       // result can be one of two:
  64       //  the old top value: the exchange succeeded
  65       //  otherwise: the new value of the top is returned.
  66       if (result == obj) {
  67         assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
  68         *actual_size = want_to_allocate;
  69         return obj;
  70       }
  71     } else {
  72       return NULL;
  73     }
  74   } while (true);
  75 }
  76 
  77 inline HeapWord* G1ContiguousSpace::allocate(size_t min_word_size,
  78                                              size_t desired_word_size,
  79                                              size_t* actual_size) {
  80   HeapWord* res = allocate_impl(min_word_size, desired_word_size, actual_size);
  81   if (res != NULL) {
  82     _bot_part.alloc_block(res, *actual_size);
  83   }
  84   return res;
  85 }
  86 
  87 inline HeapWord* G1ContiguousSpace::allocate(size_t word_size) {
  88   size_t temp;
  89   return allocate(word_size, word_size, &temp);
  90 }
  91 
  92 inline HeapWord* G1ContiguousSpace::par_allocate(size_t word_size) {
  93   size_t temp;
  94   return par_allocate(word_size, word_size, &temp);
  95 }
  96 
  97 // Because of the requirement of keeping "_offsets" up to date with the
  98 // allocations, we sequentialize these with a lock.  Therefore, best if
  99 // this is used for larger LAB allocations only.
 100 inline HeapWord* G1ContiguousSpace::par_allocate(size_t min_word_size,
 101                                                  size_t desired_word_size,
 102                                                  size_t* actual_size) {
 103   MutexLocker x(&_par_alloc_lock);
 104   return allocate(min_word_size, desired_word_size, actual_size);
 105 }
 106 
 107 inline HeapWord* G1ContiguousSpace::block_start(const void* p) {
 108   return _bot_part.block_start(p);
 109 }
 110 
 111 inline HeapWord*
 112 G1ContiguousSpace::block_start_const(const void* p) const {
 113   return _bot_part.block_start_const(p);
 114 }
 115 
 116 inline bool HeapRegion::is_obj_dead_with_size(const oop obj, const G1CMBitMap* const prev_bitmap, size_t* size) const {
 117   HeapWord* addr = (HeapWord*) obj;
 118 
 119   assert(addr < top(), "must be");
 120   assert(!is_closed_archive(),
 121          "Closed archive regions should not have references into other regions");
 122   assert(!is_humongous(), "Humongous objects not handled here");
 123   bool obj_is_dead = is_obj_dead(obj, prev_bitmap);
 124 
 125   if (ClassUnloadingWithConcurrentMark && obj_is_dead) {
 126     assert(!block_is_obj(addr), "must be");
 127     *size = block_size_using_bitmap(addr, prev_bitmap);
 128   } else {
 129     assert(block_is_obj(addr), "must be");
 130     *size = obj->size();
 131   }
 132   return obj_is_dead;
 133 }
 134 
 135 inline bool
 136 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()->prevMarkBitMap());
 181 }
 182 
 183 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t min_word_size,
 184                                                          size_t desired_word_size,
 185                                                          size_t* actual_word_size) {
 186   assert(is_young(), "we can only skip BOT updates on young regions");
 187   return par_allocate_impl(min_word_size, desired_word_size, actual_word_size);
 188 }
 189 
 190 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
 191   size_t temp;
 192   return allocate_no_bot_updates(word_size, word_size, &temp);
 193 }
 194 
 195 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t min_word_size,
 196                                                      size_t desired_word_size,
 197                                                      size_t* actual_word_size) {
 198   assert(is_young(), "we can only skip BOT updates on young regions");
 199   return allocate_impl(min_word_size, desired_word_size, actual_word_size);
 200 }
 201 
 202 inline void HeapRegion::note_start_of_marking() {
 203   _next_marked_bytes = 0;
 204   _next_top_at_mark_start = top();
 205 }
 206 
 207 inline void HeapRegion::note_end_of_marking() {
 208   _prev_top_at_mark_start = _next_top_at_mark_start;
 209   _prev_marked_bytes = _next_marked_bytes;
 210   _next_marked_bytes = 0;
 211 }
 212 
 213 inline void HeapRegion::note_start_of_copying(bool during_initial_mark) {
 214   if (is_survivor()) {
 215     // This is how we always allocate survivors.
 216     assert(_next_top_at_mark_start == bottom(), "invariant");
 217   } else {
 218     if (during_initial_mark) {
 219       // During initial-mark we'll explicitly mark any objects on old
 220       // regions that are pointed to by roots. Given that explicit
 221       // marks only make sense under NTAMS it'd be nice if we could
 222       // check that condition if we wanted to. Given that we don't
 223       // know where the top of this region will end up, we simply set
 224       // NTAMS to the end of the region so all marks will be below
 225       // NTAMS. We'll set it to the actual top when we retire this region.
 226       _next_top_at_mark_start = end();
 227     } else {
 228       // We could have re-used this old region as to-space over a
 229       // couple of GCs since the start of the concurrent marking
 230       // cycle. This means that [bottom,NTAMS) will contain objects
 231       // copied up to and including initial-mark and [NTAMS, top)
 232       // will contain objects copied during the concurrent marking cycle.
 233       assert(top() >= _next_top_at_mark_start, "invariant");
 234     }
 235   }
 236 }
 237 
 238 inline void HeapRegion::note_end_of_copying(bool during_initial_mark) {
 239   if (is_survivor()) {
 240     // This is how we always allocate survivors.
 241     assert(_next_top_at_mark_start == bottom(), "invariant");
 242   } else {
 243     if (during_initial_mark) {
 244       // See the comment for note_start_of_copying() for the details
 245       // on this.
 246       assert(_next_top_at_mark_start == end(), "pre-condition");
 247       _next_top_at_mark_start = top();
 248     } else {
 249       // See the comment for note_start_of_copying() for the details
 250       // on this.
 251       assert(top() >= _next_top_at_mark_start, "invariant");
 252     }
 253   }
 254 }
 255 
 256 inline bool HeapRegion::in_collection_set() const {
 257   return G1CollectedHeap::heap()->is_in_cset(this);
 258 }
 259 
 260 template <class Closure, bool is_gc_active>
 261 bool HeapRegion::do_oops_on_card_in_humongous(MemRegion mr,
 262                                               Closure* cl,
 263                                               G1CollectedHeap* g1h) {
 264   assert(is_humongous(), "precondition");
 265   HeapRegion* sr = humongous_start_region();
 266   oop obj = oop(sr->bottom());
 267 
 268   // If concurrent and klass_or_null is NULL, then space has been
 269   // allocated but the object has not yet been published by setting
 270   // the klass.  That can only happen if the card is stale.  However,
 271   // we've already set the card clean, so we must return failure,
 272   // since the allocating thread could have performed a write to the
 273   // card that might be missed otherwise.
 274   if (!is_gc_active && (obj->klass_or_null_acquire() == NULL)) {
 275     return false;
 276   }
 277 
 278   // We have a well-formed humongous object at the start of sr.
 279   // Only filler objects follow a humongous object in the containing
 280   // regions, and we can ignore those.  So only process the one
 281   // humongous object.
 282   if (!g1h->is_obj_dead(obj, sr)) {
 283     if (obj->is_objArray() || (sr->bottom() < mr.start())) {
 284       // objArrays are always marked precisely, so limit processing
 285       // with mr.  Non-objArrays might be precisely marked, and since
 286       // it's humongous it's worthwhile avoiding full processing.
 287       // However, the card could be stale and only cover filler
 288       // objects.  That should be rare, so not worth checking for;
 289       // instead let it fall out from the bounded iteration.
 290       obj->oop_iterate(cl, mr);
 291     } else {
 292       // If obj is not an objArray and mr contains the start of the
 293       // obj, then this could be an imprecise mark, and we need to
 294       // process the entire object.
 295       obj->oop_iterate(cl);
 296     }
 297   }
 298   return true;
 299 }
 300 
 301 template <bool is_gc_active, class Closure>
 302 bool HeapRegion::oops_on_card_seq_iterate_careful(MemRegion mr,
 303                                                   Closure* cl) {
 304   assert(MemRegion(bottom(), end()).contains(mr), "Card region not in heap region");
 305   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 306 
 307   // Special handling for humongous regions.
 308   if (is_humongous()) {
 309     return do_oops_on_card_in_humongous<Closure, is_gc_active>(mr, cl, g1h);
 310   }
 311   assert(is_old(), "precondition");
 312 
 313   // Because mr has been trimmed to what's been allocated in this
 314   // region, the parts of the heap that are examined here are always
 315   // parsable; there's no need to use klass_or_null to detect
 316   // in-progress allocation.
 317 
 318   // Cache the boundaries of the memory region in some const locals
 319   HeapWord* const start = mr.start();
 320   HeapWord* const end = mr.end();
 321 
 322   // Find the obj that extends onto mr.start().
 323   // Update BOT as needed while finding start of (possibly dead)
 324   // object containing the start of the region.
 325   HeapWord* cur = block_start(start);
 326 
 327 #ifdef ASSERT
 328   {
 329     assert(cur <= start,
 330            "cur: " PTR_FORMAT ", start: " PTR_FORMAT, p2i(cur), p2i(start));
 331     HeapWord* next = cur + block_size(cur);
 332     assert(start < next,
 333            "start: " PTR_FORMAT ", next: " PTR_FORMAT, p2i(start), p2i(next));
 334   }
 335 #endif
 336 
 337   const G1CMBitMap* const bitmap = g1h->concurrent_mark()->prevMarkBitMap();
 338   do {
 339     oop obj = oop(cur);
 340     assert(oopDesc::is_oop(obj,true), "Not an oop at " PTR_FORMAT, p2i(cur));
 341     assert(obj->klass_or_null() != NULL,
 342            "Unparsable heap at " PTR_FORMAT, p2i(cur));
 343 
 344     size_t size;
 345     bool is_dead = is_obj_dead_with_size(obj, bitmap, &size);
 346 
 347     cur += size;
 348     if (!is_dead) {
 349       // Process live object's references.
 350 
 351       // Non-objArrays are usually marked imprecise at the object
 352       // start, in which case we need to iterate over them in full.
 353       // objArrays are precisely marked, but can still be iterated
 354       // over in full if completely covered.
 355       if (!obj->is_objArray() || (((HeapWord*)obj) >= start && cur <= end)) {
 356         obj->oop_iterate(cl);
 357       } else {
 358         obj->oop_iterate(cl, mr);
 359       }
 360     }
 361   } while (cur < end);
 362 
 363   return true;
 364 }
 365 
 366 #endif // SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP