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