1 /* 2 * Copyright (c) 2012, 2016, 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 "memory/allocation.hpp" 27 #include "memory/metachunk.hpp" 28 #include "utilities/copy.hpp" 29 #include "utilities/debug.hpp" 30 31 class VirtualSpaceNode; 32 33 size_t Metachunk::object_alignment() { 34 // Must align pointers and sizes to 8, 35 // so that 64 bit types get correctly aligned. 36 const size_t alignment = 8; 37 38 // Make sure that the Klass alignment also agree. 39 STATIC_ASSERT(alignment == (size_t)KlassAlignmentInBytes); 40 41 return alignment; 42 } 43 44 size_t Metachunk::overhead() { 45 return align_up(sizeof(Metachunk), object_alignment()) / BytesPerWord; 46 } 47 48 // Metachunk methods 49 50 Metachunk::Metachunk(size_t word_size, 51 VirtualSpaceNode* container) 52 : Metabase<Metachunk>(word_size), 53 _top(NULL), 54 _container(container) 55 { 56 _top = initial_top(); 57 #ifdef ASSERT 58 set_is_tagged_free(false); 59 mangle(uninitMetaWordVal); 60 #endif 61 } 62 63 MetaWord* Metachunk::allocate(size_t word_size) { 64 MetaWord* result = NULL; 65 // If available, bump the pointer to allocate. 66 if (free_word_size() >= word_size) { 67 result = _top; 68 _top = _top + word_size; 69 } 70 return result; 71 } 72 73 // _bottom points to the start of the chunk including the overhead. 74 size_t Metachunk::used_word_size() const { 75 return pointer_delta(_top, bottom(), sizeof(MetaWord)); 76 } 77 78 size_t Metachunk::free_word_size() const { 79 return pointer_delta(end(), _top, sizeof(MetaWord)); 80 } 81 82 void Metachunk::print_on(outputStream* st) const { 83 st->print_cr("Metachunk:" 84 " bottom " PTR_FORMAT " top " PTR_FORMAT 85 " end " PTR_FORMAT " size " SIZE_FORMAT, 86 p2i(bottom()), p2i(_top), p2i(end()), word_size()); 87 if (Verbose) { 88 st->print_cr(" used " SIZE_FORMAT " free " SIZE_FORMAT, 89 used_word_size(), free_word_size()); 90 } 91 } 92 93 #ifndef PRODUCT 94 void Metachunk::mangle(juint word_value) { 95 // Overwrite the payload of the chunk and not the links that 96 // maintain list of chunks. 97 HeapWord* start = (HeapWord*)initial_top(); 98 size_t size = word_size() - overhead(); 99 Copy::fill_to_words(start, size, word_value); 100 } 101 #endif // PRODUCT 102 103 void Metachunk::verify() { 104 #ifdef ASSERT 105 // Cannot walk through the blocks unless the blocks have 106 // headers with sizes. 107 assert(bottom() <= _top && 108 _top <= (MetaWord*)end(), 109 "Chunk has been smashed"); 110 #endif 111 return; 112 } 113