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 #include "precompiled.hpp"

    26 #include "gc/cms/freeChunk.hpp"

    27 #include "utilities/copy.hpp"

    28 

    29 #ifndef PRODUCT

    30 

    31 #define baadbabeHeapWord badHeapWordVal

    32 #define deadbeefHeapWord 0xdeadbeef

    33 

    34 size_t const FreeChunk::header_size() {

    35   return sizeof(FreeChunk)/HeapWordSize;

    36 }

    37 

    38 void FreeChunk::mangleAllocated(size_t size) {

    39   // mangle all but the header of a just-allocated block

    40   // of storage

    41   assert(size >= MinChunkSize, "smallest size of object");

    42   // we can't assert that _size == size because this may be an

    43   // allocation out of a linear allocation block

    44   assert(sizeof(FreeChunk) % HeapWordSize == 0,

    45          "shouldn't write beyond chunk");

    46   HeapWord* addr = (HeapWord*)this;

    47   size_t hdr = header_size();

    48   Copy::fill_to_words(addr + hdr, size - hdr, baadbabeHeapWord);

    49 }

    50 

    51 void FreeChunk::mangleFreed(size_t sz) {

    52   assert(baadbabeHeapWord != deadbeefHeapWord, "Need distinct patterns");

    53   // mangle all but the header of a just-freed block of storage

    54   // just prior to passing it to the storage dictionary

    55   assert(sz >= MinChunkSize, "smallest size of object");

    56   assert(sz == size(), "just checking");

    57   HeapWord* addr = (HeapWord*)this;

    58   size_t hdr = header_size();

    59   Copy::fill_to_words(addr + hdr, sz - hdr, deadbeefHeapWord);

    60 }

    61 

    62 void FreeChunk::verifyList() const {

    63   FreeChunk* nextFC = next();

    64   if (nextFC != NULL) {

    65     assert(this == nextFC->prev(), "broken chain");

    66     assert(size() == nextFC->size(), "wrong size");

    67     nextFC->verifyList();

    68   }

    69 }

    70 #endif

    71 

    72 void FreeChunk::print_on(outputStream* st) {

    73   st->print_cr("Next: " PTR_FORMAT " Prev: " PTR_FORMAT " %s",

    74     p2i(next()), p2i(prev()), cantCoalesce() ? "[can't coalesce]" : "");

    75 }