1 /*
   2  * Copyright (c) 2001, 2015, 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.
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  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.inline.hpp"
  34 
  35 // This version requires locking.
  36 inline HeapWord* G1OffsetTableContigSpace::allocate_impl(size_t size,
  37                                                 HeapWord* const end_value) {
  38   HeapWord* obj = top();
  39   if (pointer_delta(end_value, obj) >= size) {
  40     HeapWord* new_top = obj + size;
  41     set_top(new_top);
  42     assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
  43     return obj;
  44   } else {
  45     return NULL;
  46   }
  47 }
  48 
  49 // This version is lock-free.
  50 inline HeapWord* G1OffsetTableContigSpace::par_allocate_impl(size_t size,
  51                                                     HeapWord* const end_value) {
  52   do {
  53     HeapWord* obj = top();
  54     if (pointer_delta(end_value, obj) >= size) {
  55       HeapWord* new_top = obj + size;
  56       HeapWord* result = (HeapWord*)Atomic::cmpxchg_ptr(new_top, top_addr(), obj);
  57       // result can be one of two:
  58       //  the old top value: the exchange succeeded
  59       //  otherwise: the new value of the top is returned.
  60       if (result == obj) {
  61         assert(is_aligned(obj) && is_aligned(new_top), "checking alignment");
  62         return obj;
  63       }
  64     } else {
  65       return NULL;
  66     }
  67   } while (true);
  68 }
  69 
  70 inline HeapWord* G1OffsetTableContigSpace::allocate(size_t size) {
  71   HeapWord* res = allocate_impl(size, end());
  72   if (res != NULL) {
  73     _offsets.alloc_block(res, size);
  74   }
  75   return res;
  76 }
  77 
  78 // Because of the requirement of keeping "_offsets" up to date with the
  79 // allocations, we sequentialize these with a lock.  Therefore, best if
  80 // this is used for larger LAB allocations only.
  81 inline HeapWord* G1OffsetTableContigSpace::par_allocate(size_t size) {
  82   MutexLocker x(&_par_alloc_lock);
  83   return allocate(size);
  84 }
  85 
  86 inline HeapWord* G1OffsetTableContigSpace::block_start(const void* p) {
  87   return _offsets.block_start(p);
  88 }
  89 
  90 inline HeapWord*
  91 G1OffsetTableContigSpace::block_start_const(const void* p) const {
  92   return _offsets.block_start_const(p);
  93 }
  94 
  95 inline bool
  96 HeapRegion::block_is_obj(const HeapWord* p) const {
  97   G1CollectedHeap* g1h = G1CollectedHeap::heap();
  98   if (ClassUnloadingWithConcurrentMark) {
  99     return !g1h->is_obj_dead(oop(p), this);
 100   }
 101   return p < top();
 102 }
 103 
 104 inline size_t
 105 HeapRegion::block_size(const HeapWord *addr) const {
 106   if (addr == top()) {
 107     return pointer_delta(end(), addr);
 108   }
 109 
 110   if (block_is_obj(addr)) {
 111     return oop(addr)->size();
 112   }
 113 
 114   assert(ClassUnloadingWithConcurrentMark,
 115       err_msg("All blocks should be objects if G1 Class Unloading isn't used. "
 116               "HR: [" PTR_FORMAT ", " PTR_FORMAT ", " PTR_FORMAT ") "
 117               "addr: " PTR_FORMAT,
 118               p2i(bottom()), p2i(top()), p2i(end()), p2i(addr)));
 119 
 120   // Old regions' dead objects may have dead classes
 121   // We need to find the next live object in some other
 122   // manner than getting the oop size
 123   G1CollectedHeap* g1h = G1CollectedHeap::heap();
 124   HeapWord* next = g1h->concurrent_mark()->prevMarkBitMap()->
 125       getNextMarkedWordAddress(addr, prev_top_at_mark_start());
 126 
 127   assert(next > addr, "must get the next live object");
 128   return pointer_delta(next, addr);
 129 }
 130 
 131 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t word_size) {
 132   assert(is_young(), "we can only skip BOT updates on young regions");
 133   return par_allocate_impl(word_size, end());
 134 }
 135 
 136 inline HeapWord* HeapRegion::allocate_no_bot_updates(size_t word_size) {
 137   assert(is_young(), "we can only skip BOT updates on young regions");
 138   return allocate_impl(word_size, end());
 139 }
 140 
 141 inline void HeapRegion::note_start_of_marking() {
 142   _next_marked_bytes = 0;
 143   _next_top_at_mark_start = top();
 144 }
 145 
 146 inline void HeapRegion::note_end_of_marking() {
 147   _prev_top_at_mark_start = _next_top_at_mark_start;
 148   _prev_marked_bytes = _next_marked_bytes;
 149   _next_marked_bytes = 0;
 150 
 151   assert(_prev_marked_bytes <=
 152          (size_t) pointer_delta(prev_top_at_mark_start(), bottom()) *
 153          HeapWordSize, "invariant");
 154 }
 155 
 156 inline void HeapRegion::note_start_of_copying(bool during_initial_mark) {
 157   if (is_survivor()) {
 158     // This is how we always allocate survivors.
 159     assert(_next_top_at_mark_start == bottom(), "invariant");
 160   } else {
 161     if (during_initial_mark) {
 162       // During initial-mark we'll explicitly mark any objects on old
 163       // regions that are pointed to by roots. Given that explicit
 164       // marks only make sense under NTAMS it'd be nice if we could
 165       // check that condition if we wanted to. Given that we don't
 166       // know where the top of this region will end up, we simply set
 167       // NTAMS to the end of the region so all marks will be below
 168       // NTAMS. We'll set it to the actual top when we retire this region.
 169       _next_top_at_mark_start = end();
 170     } else {
 171       // We could have re-used this old region as to-space over a
 172       // couple of GCs since the start of the concurrent marking
 173       // cycle. This means that [bottom,NTAMS) will contain objects
 174       // copied up to and including initial-mark and [NTAMS, top)
 175       // will contain objects copied during the concurrent marking cycle.
 176       assert(top() >= _next_top_at_mark_start, "invariant");
 177     }
 178   }
 179 }
 180 
 181 inline void HeapRegion::note_end_of_copying(bool during_initial_mark) {
 182   if (is_survivor()) {
 183     // This is how we always allocate survivors.
 184     assert(_next_top_at_mark_start == bottom(), "invariant");
 185   } else {
 186     if (during_initial_mark) {
 187       // See the comment for note_start_of_copying() for the details
 188       // on this.
 189       assert(_next_top_at_mark_start == end(), "pre-condition");
 190       _next_top_at_mark_start = top();
 191     } else {
 192       // See the comment for note_start_of_copying() for the details
 193       // on this.
 194       assert(top() >= _next_top_at_mark_start, "invariant");
 195     }
 196   }
 197 }
 198 
 199 inline bool HeapRegion::in_collection_set() const {
 200   return G1CollectedHeap::heap()->is_in_cset(this);
 201 }
 202 
 203 inline HeapRegion* HeapRegion::next_in_collection_set() const {
 204   assert(in_collection_set(), "should only invoke on member of CS.");
 205   assert(_next_in_special_set == NULL ||
 206          _next_in_special_set->in_collection_set(),
 207          "Malformed CS.");
 208   return _next_in_special_set;
 209 }
 210 
 211 void HeapRegion::set_next_in_collection_set(HeapRegion* r) {
 212   assert(in_collection_set(), "should only invoke on member of CS.");
 213   assert(r == NULL || r->in_collection_set(), "Malformed CS.");
 214   _next_in_special_set = r;
 215 }
 216 
 217 #endif // SHARE_VM_GC_G1_HEAPREGION_INLINE_HPP