1 /*
   2  * Copyright (c) 2001, 2019, 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
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  24 
  25 #ifndef SHARE_GC_G1_G1BLOCKOFFSETTABLE_INLINE_HPP
  26 #define SHARE_GC_G1_G1BLOCKOFFSETTABLE_INLINE_HPP
  27 
  28 #include "gc/g1/g1BlockOffsetTable.hpp"
  29 #include "gc/g1/heapRegion.hpp"
  30 #include "gc/shared/memset_with_concurrent_readers.hpp"
  31 #include "runtime/atomic.hpp"
  32 
  33 inline HeapWord* G1BlockOffsetTablePart::block_start(const void* addr) {
  34   if (addr >= _hr->bottom() && addr < _hr->end()) {
  35     HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1);
  36     return forward_to_block_containing_addr(q, addr);
  37   } else {
  38     return NULL;
  39   }
  40 }
  41 
  42 inline HeapWord* G1BlockOffsetTablePart::block_start_const(const void* addr) const {
  43   if (addr >= _hr->bottom() && addr < _hr->end()) {
  44     HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1);
  45     HeapWord* n = q + block_size(q);
  46     return forward_to_block_containing_addr_const(q, n, addr);
  47   } else {
  48     return NULL;
  49   }
  50 }
  51 
  52 u_char G1BlockOffsetTable::offset_array(size_t index) const {
  53   check_index(index, "index out of range");
  54   return Atomic::load(&_offset_array[index]);
  55 }
  56 
  57 void G1BlockOffsetTable::set_offset_array_raw(size_t index, u_char offset) {
  58   Atomic::store(&_offset_array[index], offset);
  59 }
  60 
  61 void G1BlockOffsetTable::set_offset_array(size_t index, u_char offset) {
  62   check_index(index, "index out of range");
  63   set_offset_array_raw(index, offset);
  64 }
  65 
  66 void G1BlockOffsetTable::set_offset_array(size_t index, HeapWord* high, HeapWord* low) {
  67   check_index(index, "index out of range");
  68   assert(high >= low, "addresses out of order");
  69   size_t offset = pointer_delta(high, low);
  70   check_offset(offset, "offset too large");
  71   set_offset_array(index, (u_char)offset);
  72 }
  73 
  74 void G1BlockOffsetTable::set_offset_array(size_t left, size_t right, u_char offset) {
  75   check_index(right, "right index out of range");
  76   assert(left <= right, "indexes out of order");
  77   size_t num_cards = right - left + 1;
  78   memset_with_concurrent_readers
  79     (const_cast<u_char*> (&_offset_array[left]), offset, num_cards);
  80 }
  81 
  82 // Variant of index_for that does not check the index for validity.
  83 inline size_t G1BlockOffsetTable::index_for_raw(const void* p) const {
  84   return pointer_delta((char*)p, _reserved.start(), sizeof(char)) >> BOTConstants::LogN;
  85 }
  86 
  87 inline size_t G1BlockOffsetTable::index_for(const void* p) const {
  88   char* pc = (char*)p;
  89   assert(pc >= (char*)_reserved.start() &&
  90          pc <  (char*)_reserved.end(),
  91          "p (" PTR_FORMAT ") not in reserved [" PTR_FORMAT ", " PTR_FORMAT ")",
  92          p2i(p), p2i(_reserved.start()), p2i(_reserved.end()));
  93   size_t result = index_for_raw(p);
  94   check_index(result, "bad index from address");
  95   return result;
  96 }
  97 
  98 inline HeapWord* G1BlockOffsetTable::address_for_index(size_t index) const {
  99   check_index(index, "index out of range");
 100   HeapWord* result = address_for_index_raw(index);
 101   assert(result >= _reserved.start() && result < _reserved.end(),
 102          "bad address from index result " PTR_FORMAT
 103          " _reserved.start() " PTR_FORMAT " _reserved.end() " PTR_FORMAT,
 104          p2i(result), p2i(_reserved.start()), p2i(_reserved.end()));
 105   return result;
 106 }
 107 
 108 inline size_t G1BlockOffsetTablePart::block_size(const HeapWord* p) const {
 109   return _hr->block_size(p);
 110 }
 111 
 112 inline HeapWord* G1BlockOffsetTablePart::block_at_or_preceding(const void* addr,
 113                                                                bool has_max_index,
 114                                                                size_t max_index) const {
 115   assert(_object_can_span || _bot->offset_array(_bot->index_for(_hr->bottom())) == 0,
 116          "Object crossed region boundary, found offset %u instead of 0",
 117          (uint) _bot->offset_array(_bot->index_for(_hr->bottom())));
 118   size_t index = _bot->index_for(addr);
 119   // We must make sure that the offset table entry we use is valid.  If
 120   // "addr" is past the end, start at the last known one and go forward.
 121   if (has_max_index) {
 122     index = MIN2(index, max_index);
 123   }
 124   HeapWord* q = _bot->address_for_index(index);
 125 
 126   uint offset = _bot->offset_array(index);  // Extend u_char to uint.
 127   while (offset >= BOTConstants::N_words) {
 128     // The excess of the offset from N_words indicates a power of Base
 129     // to go back by.
 130     size_t n_cards_back = BOTConstants::entry_to_cards_back(offset);
 131     q -= (BOTConstants::N_words * n_cards_back);
 132     index -= n_cards_back;
 133     offset = _bot->offset_array(index);
 134   }
 135   assert(offset < BOTConstants::N_words, "offset too large");
 136   q -= offset;
 137   return q;
 138 }
 139 
 140 inline HeapWord* G1BlockOffsetTablePart::forward_to_block_containing_addr_const(HeapWord* q, HeapWord* n,
 141                                                                                 const void* addr) const {
 142   if (addr >= _hr->top()) return _hr->top();
 143   while (n <= addr) {
 144     q = n;
 145     oop obj = oop(q);
 146     if (obj->klass_or_null_acquire() == NULL) {
 147       return q;
 148     }
 149     n += block_size(q);
 150   }
 151   assert(q <= n, "wrong order for q and addr");
 152   assert(addr < n, "wrong order for addr and n");
 153   return q;
 154 }
 155 
 156 inline HeapWord* G1BlockOffsetTablePart::forward_to_block_containing_addr(HeapWord* q,
 157                                                                           const void* addr) {
 158   if (oop(q)->klass_or_null_acquire() == NULL) {
 159     return q;
 160   }
 161   HeapWord* n = q + block_size(q);
 162   // In the normal case, where the query "addr" is a card boundary, and the
 163   // offset table chunks are the same size as cards, the block starting at
 164   // "q" will contain addr, so the test below will fail, and we'll fall
 165   // through quickly.
 166   if (n <= addr) {
 167     q = forward_to_block_containing_addr_slow(q, n, addr);
 168   }
 169   assert(q <= addr, "wrong order for current and arg");
 170   return q;
 171 }
 172 
 173 #endif // SHARE_GC_G1_G1BLOCKOFFSETTABLE_INLINE_HPP
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