1 /*
   2  * Copyright (c) 2001, 2014, 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 #include "precompiled.hpp"
  26 #include "gc_implementation/concurrentMarkSweep/freeChunk.hpp"
  27 #include "memory/freeBlockDictionary.hpp"
  28 #include "utilities/copy.hpp"
  29 
  30 #ifndef PRODUCT
  31 
  32 #define baadbabeHeapWord badHeapWordVal
  33 #define deadbeefHeapWord 0xdeadbeef
  34 
  35 size_t const FreeChunk::header_size() {
  36   return sizeof(FreeChunk)/HeapWordSize;
  37 }
  38 
  39 void FreeChunk::mangleAllocated(size_t size) {
  40   // mangle all but the header of a just-allocated block
  41   // of storage
  42   assert(size >= MinChunkSize, "smallest size of object");
  43   // we can't assert that _size == size because this may be an
  44   // allocation out of a linear allocation block
  45   assert(sizeof(FreeChunk) % HeapWordSize == 0,
  46          "shouldn't write beyond chunk");
  47   HeapWord* addr = (HeapWord*)this;
  48   size_t hdr = header_size();
  49   Copy::fill_to_words(addr + hdr, size - hdr, baadbabeHeapWord);
  50 }
  51 
  52 void FreeChunk::mangleFreed(size_t sz) {
  53   assert(baadbabeHeapWord != deadbeefHeapWord, "Need distinct patterns");
  54   // mangle all but the header of a just-freed block of storage
  55   // just prior to passing it to the storage dictionary
  56   assert(sz >= MinChunkSize, "smallest size of object");
  57   assert(sz == size(), "just checking");
  58   HeapWord* addr = (HeapWord*)this;
  59   size_t hdr = header_size();
  60   Copy::fill_to_words(addr + hdr, sz - hdr, deadbeefHeapWord);
  61 }
  62 
  63 void FreeChunk::verifyList() const {
  64   FreeChunk* nextFC = next();
  65   if (nextFC != NULL) {
  66     assert(this == nextFC->prev(), "broken chain");
  67     assert(size() == nextFC->size(), "wrong size");
  68     nextFC->verifyList();
  69   }
  70 }
  71 #endif
  72 
  73 void FreeChunk::print_on(outputStream* st) {
  74   st->print_cr("Next: " PTR_FORMAT " Prev: " PTR_FORMAT " %s",
  75     p2i(next()), p2i(prev()), cantCoalesce() ? "[can't coalesce]" : "");
  76 }