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 public:
130 CodeHeap();
131
132 // Heap extents
133 bool reserve(size_t reserved_size, size_t committed_size, size_t segment_size);
134 bool expand_by(size_t size); // expands committed memory by size
135
136 // Memory allocation
137 void* allocate (size_t size, bool is_critical); // allocates a block of size or returns NULL
138 void deallocate(void* p); // deallocates a block
139
140 // Attributes
141 char* low_boundary() const { return _memory.low_boundary (); }
142 char* high() const { return _memory.high(); }
143 char* high_boundary() const { return _memory.high_boundary(); }
144
145 bool contains(const void* p) const { return low_boundary() <= p && p < high(); }
146 void* find_start(void* p) const; // returns the block containing p or NULL
147 size_t alignment_unit() const; // alignment of any block
148 size_t alignment_offset() const; // offset of first byte of any block, within the enclosing alignment unit
149 static size_t header_size(); // returns the header size for each heap block
150
151 size_t allocated_in_freelist() const { return _freelist_segments * CodeCacheSegmentSize; }
152 int freelist_length() const { return _freelist_length; } // number of elements in the freelist
153
154 // returns the first block or NULL
155 void* first() const { return next_free(first_block()); }
156 // returns the next block given a block p or NULL
157 void* next(void* p) const { return next_free(next_block(block_start(p))); }
158
159 // Statistics
160 size_t capacity() const;
161 size_t max_capacity() const;
162 int allocated_segments() const;
163 size_t allocated_capacity() const;
164 size_t unallocated_capacity() const { return max_capacity() - allocated_capacity(); }
165
166 private:
167 size_t heap_unallocated_capacity() const;
168
169 public:
170 // Debugging
171 void verify() PRODUCT_RETURN;
172 void print() PRODUCT_RETURN;
173 };
174
175 #endif // SHARE_VM_MEMORY_HEAP_HPP