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_G1BLOCKOFFSETTABLE_INLINE_HPP
  26 #define SHARE_VM_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 "gc/shared/space.hpp"
  32 #include "runtime/atomic.hpp"
  33 
  34 inline HeapWord* G1BlockOffsetTablePart::block_start(const void* addr) {
  35   if (addr >= _space->bottom() && addr < _space->end()) {
  36     HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1);
  37     return forward_to_block_containing_addr(q, addr);
  38   } else {
  39     return NULL;
  40   }
  41 }
  42 
  43 inline HeapWord* G1BlockOffsetTablePart::block_start_const(const void* addr) const {
  44   if (addr >= _space->bottom() && addr < _space->end()) {
  45     HeapWord* q = block_at_or_preceding(addr, true, _next_offset_index-1);
  46     HeapWord* n = q + block_size(q);
  47     return forward_to_block_containing_addr_const(q, n, addr);
  48   } else {
  49     return NULL;
  50   }
  51 }
  52 
  53 u_char G1BlockOffsetTable::offset_array(size_t index) const {
  54   check_index(index, "index out of range");
  55   return Atomic::load(&_offset_array[index]);
  56 }
  57 
  58 void G1BlockOffsetTable::set_offset_array(size_t index, u_char offset) {
  59   check_index(index, "index out of range");
  60   Atomic::store(offset, &_offset_array[index]);
  61 }
  62 
  63 void G1BlockOffsetTable::set_offset_array(size_t index, HeapWord* high, HeapWord* low) {
  64   check_index(index, "index out of range");
  65   assert(high >= low, "addresses out of order");
  66   size_t offset = pointer_delta(high, low);
  67   check_offset(offset, "offset too large");
  68   set_offset_array(index, (u_char)offset);
  69 }
  70 
  71 void G1BlockOffsetTable::set_offset_array(size_t left, size_t right, u_char offset) {
  72   check_index(right, "right index out of range");
  73   assert(left <= right, "indexes out of order");
  74   size_t num_cards = right - left + 1;
  75   memset_with_concurrent_readers
  76     (const_cast<u_char*> (&_offset_array[left]), offset, num_cards);
  77 }
  78 
  79 // Variant of index_for that does not check the index for validity.
  80 inline size_t G1BlockOffsetTable::index_for_raw(const void* p) const {
  81   return pointer_delta((char*)p, _reserved.start(), sizeof(char)) >> BOTConstants::LogN;
  82 }
  83 
  84 inline size_t G1BlockOffsetTable::index_for(const void* p) const {
  85   char* pc = (char*)p;
  86   assert(pc >= (char*)_reserved.start() &&
  87          pc <  (char*)_reserved.end(),
  88          "p (" PTR_FORMAT ") not in reserved [" PTR_FORMAT ", " PTR_FORMAT ")",
  89          p2i(p), p2i(_reserved.start()), p2i(_reserved.end()));
  90   size_t result = index_for_raw(p);
  91   check_index(result, "bad index from address");
  92   return result;
  93 }
  94 
  95 inline HeapWord* G1BlockOffsetTable::address_for_index(size_t index) const {
  96   check_index(index, "index out of range");
  97   HeapWord* result = address_for_index_raw(index);
  98   assert(result >= _reserved.start() && result < _reserved.end(),
  99          "bad address from index result " PTR_FORMAT
 100          " _reserved.start() " PTR_FORMAT " _reserved.end() " PTR_FORMAT,
 101          p2i(result), p2i(_reserved.start()), p2i(_reserved.end()));
 102   return result;
 103 }
 104 
 105 inline size_t G1BlockOffsetTablePart::block_size(const HeapWord* p) const {
 106   return _space->block_size(p);
 107 }
 108 
 109 inline HeapWord* G1BlockOffsetTablePart::block_at_or_preceding(const void* addr,
 110                                                                bool has_max_index,
 111                                                                size_t max_index) const {
 112   assert(_object_can_span || _bot->offset_array(_bot->index_for(_space->bottom())) == 0,
 113          "Object crossed region boundary, found offset %u instead of 0",
 114          (uint) _bot->offset_array(_bot->index_for(_space->bottom())));
 115   size_t index = _bot->index_for(addr);
 116   // We must make sure that the offset table entry we use is valid.  If
 117   // "addr" is past the end, start at the last known one and go forward.
 118   if (has_max_index) {
 119     index = MIN2(index, max_index);
 120   }
 121   HeapWord* q = _bot->address_for_index(index);
 122 
 123   uint offset = _bot->offset_array(index);  // Extend u_char to uint.
 124   while (offset >= BOTConstants::N_words) {
 125     // The excess of the offset from N_words indicates a power of Base
 126     // to go back by.
 127     size_t n_cards_back = BOTConstants::entry_to_cards_back(offset);
 128     q -= (BOTConstants::N_words * n_cards_back);
 129     index -= n_cards_back;
 130     offset = _bot->offset_array(index);
 131   }
 132   assert(offset < BOTConstants::N_words, "offset too large");
 133   q -= offset;
 134   return q;
 135 }
 136 
 137 inline HeapWord* G1BlockOffsetTablePart::forward_to_block_containing_addr_const(HeapWord* q, HeapWord* n,
 138                                                                                 const void* addr) const {
 139   if (addr >= _space->top()) return _space->top();
 140   while (n <= addr) {
 141     q = n;
 142     oop obj = oop(q);
 143     if (obj->klass_or_null_acquire() == NULL) {
 144       return q;
 145     }
 146     n += block_size(q);
 147   }
 148   assert(q <= n, "wrong order for q and addr");
 149   assert(addr < n, "wrong order for addr and n");
 150   return q;
 151 }
 152 
 153 inline HeapWord* G1BlockOffsetTablePart::forward_to_block_containing_addr(HeapWord* q,
 154                                                                           const void* addr) {
 155   if (oop(q)->klass_or_null_acquire() == NULL) {
 156     return q;
 157   }
 158   HeapWord* n = q + block_size(q);
 159   // In the normal case, where the query "addr" is a card boundary, and the
 160   // offset table chunks are the same size as cards, the block starting at
 161   // "q" will contain addr, so the test below will fail, and we'll fall
 162   // through quickly.
 163   if (n <= addr) {
 164     q = forward_to_block_containing_addr_slow(q, n, addr);
 165   }
 166   assert(q <= addr, "wrong order for current and arg");
 167   return q;
 168 }
 169 
 170 #endif // SHARE_VM_GC_G1_G1BLOCKOFFSETTABLE_INLINE_HPP