1 /* 2 * Copyright (c) 1997, 2013, 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 #ifndef SHARE_VM_MEMORY_HEAP_HPP 26 #define SHARE_VM_MEMORY_HEAP_HPP 27 28 #include "memory/allocation.hpp" 29 #include "runtime/virtualspace.hpp" 30 31 // Blocks 32 33 class HeapBlock VALUE_OBJ_CLASS_SPEC { 34 friend class VMStructs; 35 36 public: 37 struct Header { 38 size_t _length; // the length in segments 39 bool _used; // Used bit 40 }; 41 42 protected: 43 union { 44 Header _header; 45 int64_t _padding[ (sizeof(Header) + sizeof(int64_t)-1) / sizeof(int64_t) ]; 46 // pad to 0 mod 8 47 }; 48 49 public: 50 // Initialization 51 void initialize(size_t length) { _header._length = length; set_used(); } 52 53 // Accessors 54 void* allocated_space() const { return (void*)(this + 1); } 55 size_t length() const { return _header._length; } 56 57 // Used/free 58 void set_used() { _header._used = true; } 59 void set_free() { _header._used = false; } 60 bool free() { return !_header._used; } 61 }; 62 63 class FreeBlock: public HeapBlock { 64 friend class VMStructs; 65 protected: 66 FreeBlock* _link; 67 68 public: 69 // Initialization 70 void initialize(size_t length) { HeapBlock::initialize(length); _link= NULL; } 71 72 // Merging 73 void set_length(size_t l) { _header._length = l; } 74 75 // Accessors 76 FreeBlock* link() const { return _link; } 77 void set_link(FreeBlock* link) { _link = link; } 78 }; 79 80 class CodeHeap : public CHeapObj<mtCode> { 81 friend class VMStructs; 82 private: 83 VirtualSpace _memory; // the memory holding the blocks 84 VirtualSpace _segmap; // the memory holding the segment map 85 86 size_t _number_of_committed_segments; 87 size_t _number_of_reserved_segments; 88 size_t _segment_size; 89 int _log2_segment_size; 90 91 size_t _next_segment; 92 93 FreeBlock* _freelist; 94 size_t _freelist_segments; // No. of segments in freelist 95 int _freelist_length; 96 97 enum { free_sentinel = 0xFF }; 98 99 // Helper functions 100 size_t size_to_segments(size_t size) const { return (size + _segment_size - 1) >> _log2_segment_size; } 101 size_t segments_to_size(size_t number_of_segments) const { return number_of_segments << _log2_segment_size; } 102 103 size_t segment_for(void* p) const { return ((char*)p - _memory.low()) >> _log2_segment_size; } 104 bool is_segment_unused(int val) const { return val == free_sentinel; } 105 HeapBlock* block_at(size_t i) const { return (HeapBlock*)(_memory.low() + (i << _log2_segment_size)); } 106 107 void mark_segmap_as_free(size_t beg, size_t end); 108 void mark_segmap_as_used(size_t beg, size_t end); 109 110 // Freelist management helpers 111 FreeBlock* following_block(FreeBlock* b); 112 void insert_after(FreeBlock* a, FreeBlock* b); 113 bool merge_right (FreeBlock* a); 114 115 // Toplevel freelist management 116 void add_to_freelist(HeapBlock* b); 117 FreeBlock* search_freelist(size_t length, bool is_critical); 118 119 // Iteration helpers 120 void* next_free(HeapBlock* b) const; 121 HeapBlock* first_block() const; 122 HeapBlock* next_block(HeapBlock* b) const; 123 HeapBlock* block_start(void* p) const; 124 125 // to perform additional actions on creation of executable code 126 void on_code_mapping(char* base, size_t size); 127 void clear(); // clears all heap contents 128 129 130 public: 131 CodeHeap(); 132 133 // Heap extents 134 bool reserve(size_t reserved_size, size_t committed_size, size_t segment_size); 135 bool expand_by(size_t size); // expands committed memory by size 136 137 // Memory allocation 138 void* allocate (size_t size, bool is_critical); // allocates a block of size or returns NULL 139 void deallocate(void* p); // deallocates a block 140 141 // Attributes 142 char* low_boundary() const { return _memory.low_boundary (); } 143 char* high() const { return _memory.high(); } 144 char* high_boundary() const { return _memory.high_boundary(); } 145 146 bool contains(const void* p) const { return low_boundary() <= p && p < high(); } 147 void* find_start(void* p) const; // returns the block containing p or NULL 148 size_t alignment_unit() const; // alignment of any block 149 size_t alignment_offset() const; // offset of first byte of any block, within the enclosing alignment unit 150 static size_t header_size(); // returns the header size for each heap block 151 152 size_t allocated_in_freelist() const { return _freelist_segments * CodeCacheSegmentSize; } 153 int freelist_length() const { return _freelist_length; } // number of elements in the freelist 154 155 // returns the first block or NULL 156 void* first() const { return next_free(first_block()); } 157 // returns the next block given a block p or NULL 158 void* next(void* p) const { return next_free(next_block(block_start(p))); } 159 160 // Statistics 161 size_t capacity() const; 162 size_t max_capacity() const; 163 int allocated_segments() const; 164 size_t allocated_capacity() const; 165 size_t unallocated_capacity() const { return max_capacity() - allocated_capacity(); } 166 167 private: 168 size_t heap_unallocated_capacity() const; 169 170 public: 171 // Debugging 172 void verify() PRODUCT_RETURN; 173 void print() PRODUCT_RETURN; 174 }; 175 176 #endif // SHARE_VM_MEMORY_HEAP_HPP