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(ChunkIndex chunktype, bool is_class, size_t word_size,
  52                      VirtualSpaceNode* container)
  53     : Metabase<Metachunk>(word_size),
  54     _chunk_type(chunktype),
  55     _is_class(is_class),
  56     _sentinel(CHUNK_SENTINEL),
  57     _origin(origin_normal),
  58     _use_count(0),
  59     _top(NULL),
  60     _container(container)
  61 {
  62   _top = initial_top();
  63   set_is_tagged_free(false);
  64 #ifdef ASSERT
  65   mangle(uninitMetaWordVal);
  66   verify();
  67 #endif
  68 }
  69 
  70 MetaWord* Metachunk::allocate(size_t word_size) {
  71   MetaWord* result = NULL;
  72   // If available, bump the pointer to allocate.
  73   if (free_word_size() >= word_size) {
  74     result = _top;
  75     _top = _top + word_size;
  76   }
  77   return result;
  78 }
  79 
  80 // _bottom points to the start of the chunk including the overhead.
  81 size_t Metachunk::used_word_size() const {
  82   return pointer_delta(_top, bottom(), sizeof(MetaWord));
  83 }
  84 
  85 size_t Metachunk::free_word_size() const {
  86   return pointer_delta(end(), _top, sizeof(MetaWord));
  87 }
  88 
  89 void Metachunk::print_on(outputStream* st) const {
  90   st->print_cr("Metachunk:"
  91                " bottom " PTR_FORMAT " top " PTR_FORMAT
  92                " end " PTR_FORMAT " size " SIZE_FORMAT " (%s)",
  93                p2i(bottom()), p2i(_top), p2i(end()), word_size(),
  94                chunk_size_name(get_chunk_type()));
  95   if (Verbose) {
  96     st->print_cr("    used " SIZE_FORMAT " free " SIZE_FORMAT,
  97                  used_word_size(), free_word_size());
  98   }
  99 }
 100 
 101 #ifdef ASSERT
 102 void Metachunk::mangle(juint word_value) {
 103   // Overwrite the payload of the chunk and not the links that
 104   // maintain list of chunks.
 105   HeapWord* start = (HeapWord*)initial_top();
 106   size_t size = word_size() - overhead();
 107   Copy::fill_to_words(start, size, word_value);
 108 }
 109 
 110 void Metachunk::verify() {
 111   assert(is_valid_sentinel(), "Chunk " PTR_FORMAT ": sentinel invalid", p2i(this));
 112   const ChunkIndex chunk_type = get_chunk_type();
 113   assert(is_valid_chunktype(chunk_type), "Chunk " PTR_FORMAT ": Invalid chunk type.", p2i(this));
 114   if (chunk_type != HumongousIndex) {
 115     assert(word_size() == get_size_for_nonhumongous_chunktype(chunk_type, is_class()),
 116            "Chunk " PTR_FORMAT ": wordsize " SIZE_FORMAT " does not fit chunk type %s.",
 117            p2i(this), word_size(), chunk_size_name(chunk_type));
 118   }
 119   assert(is_valid_chunkorigin(get_origin()), "Chunk " PTR_FORMAT ": Invalid chunk origin.", p2i(this));
 120   assert(bottom() <= _top && _top <= (MetaWord*)end(),
 121          "Chunk " PTR_FORMAT ": Chunk top out of chunk bounds.", p2i(this));
 122 
 123   // For non-humongous chunks, starting address shall be aligned
 124   // to its chunk size. Humongous chunks start address is
 125   // aligned to specialized chunk size.
 126   const size_t required_alignment =
 127     (chunk_type != HumongousIndex ? word_size() : get_size_for_nonhumongous_chunktype(SpecializedIndex, is_class())) * sizeof(MetaWord);
 128   assert(is_aligned((address)this, required_alignment),
 129          "Chunk " PTR_FORMAT ": (size " SIZE_FORMAT ") not aligned to " SIZE_FORMAT ".",
 130          p2i(this), word_size() * sizeof(MetaWord), required_alignment);
 131 }
 132 
 133 #endif // ASSERT
 134 
 135 // Helper, returns a descriptive name for the given index.
 136 const char* chunk_size_name(ChunkIndex index) {
 137   switch (index) {
 138     case SpecializedIndex:
 139       return "specialized";
 140     case SmallIndex:
 141       return "small";
 142     case MediumIndex:
 143       return "medium";
 144     case HumongousIndex:
 145       return "humongous";
 146     default:
 147       return "Invalid index";
 148   }
 149 }