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/align.hpp" 29 #include "utilities/copy.hpp" 30 #include "utilities/debug.hpp" 31 32 class VirtualSpaceNode; 33 34 size_t Metachunk::object_alignment() { 35 // Must align pointers and sizes to 8, 36 // so that 64 bit types get correctly aligned. 37 const size_t alignment = 8; 38 39 // Make sure that the Klass alignment also agree. 40 STATIC_ASSERT(alignment == (size_t)KlassAlignmentInBytes); 41 42 return alignment; 43 } 44 45 size_t Metachunk::overhead() { 46 return align_up(sizeof(Metachunk), object_alignment()) / BytesPerWord; 47 } 48 49 // Metachunk methods 50 51 Metachunk::Metachunk(size_t word_size, 52 VirtualSpaceNode* container) 53 : Metabase<Metachunk>(word_size), 54 _top(NULL), 55 _container(container) 56 { 57 _top = initial_top(); 58 #ifdef ASSERT 59 set_is_tagged_free(false); 60 mangle(uninitMetaWordVal); 61 #endif 62 } 63 64 MetaWord* Metachunk::allocate(size_t word_size) { 65 MetaWord* result = NULL; 66 // If available, bump the pointer to allocate. 67 if (free_word_size() >= word_size) { 68 result = _top; 69 _top = _top + word_size; 70 } 71 return result; 72 } 73 74 // _bottom points to the start of the chunk including the overhead. 75 size_t Metachunk::used_word_size() const { 76 return pointer_delta(_top, bottom(), sizeof(MetaWord)); 77 } 78 79 size_t Metachunk::free_word_size() const { 80 return pointer_delta(end(), _top, sizeof(MetaWord)); 81 } 82 83 void Metachunk::print_on(outputStream* st) const { 84 st->print_cr("Metachunk:" 85 " bottom " PTR_FORMAT " top " PTR_FORMAT 86 " end " PTR_FORMAT " size " SIZE_FORMAT, 87 p2i(bottom()), p2i(_top), p2i(end()), word_size()); 88 if (Verbose) { 89 st->print_cr(" used " SIZE_FORMAT " free " SIZE_FORMAT, 90 used_word_size(), free_word_size()); 91 } 92 } 93 94 #ifndef PRODUCT 95 void Metachunk::mangle(juint word_value) { 96 // Overwrite the payload of the chunk and not the links that 97 // maintain list of chunks. 98 HeapWord* start = (HeapWord*)initial_top(); 99 size_t size = word_size() - overhead(); 100 Copy::fill_to_words(start, size, word_value); 101 } 102 #endif // PRODUCT 103 104 void Metachunk::verify() { 105 #ifdef ASSERT 106 // Cannot walk through the blocks unless the blocks have 107 // headers with sizes. 108 assert(bottom() <= _top && 109 _top <= (MetaWord*)end(), 110 "Chunk has been smashed"); 111 #endif 112 return; 113 } 114