1 /*
2 * Copyright (c) 1998, 2018, 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_ADLC_ARENA_HPP
26 #define SHARE_VM_ADLC_ARENA_HPP
27
28 // All classes in adlc may be derived
29 // from one of the following allocation classes:
30 //
31 // For objects allocated in the C-heap (managed by: malloc & free).
32 // - CHeapObj
33 //
34 // For classes used as name spaces.
35 // - AllStatic
36 //
37
38 class CHeapObj {
39 public:
40 void* operator new(size_t size) throw();
41 void operator delete(void* p);
42 void* new_array(size_t size);
43 };
44
45
46 // Base class for classes that constitute name spaces.
47
48 class AllStatic {
49 public:
50 void* operator new(size_t size) throw();
51 void operator delete(void* p);
52 };
53
54
55 //------------------------------Chunk------------------------------------------
56 // Linked list of raw memory chunks
57 class Chunk: public CHeapObj {
58 private:
59 // This ordinary operator delete is needed even though not used, so the
60 // below two-argument operator delete will be treated as a placement
61 // delete rather than an ordinary sized delete; see C++14 3.7.4.2/p2.
62 void operator delete(void* p);
63 public:
64 void* operator new(size_t size, size_t length) throw();
65 void operator delete(void* p, size_t length);
66 Chunk(size_t length);
67
68 enum {
69 init_size = 1*1024, // Size of first chunk
70 size = 32*1024 // Default size of an Arena chunk (following the first)
71 };
72 Chunk* _next; // Next Chunk in list
73 size_t _len; // Size of this Chunk
74
75 void chop(); // Chop this chunk
76 void next_chop(); // Chop next chunk
77
78 // Boundaries of data area (possibly unused)
79 char* bottom() const { return ((char*) this) + sizeof(Chunk); }
80 char* top() const { return bottom() + _len; }
81 };
82
83
84 //------------------------------Arena------------------------------------------
85 // Fast allocation of memory
86 class Arena: public CHeapObj {
87 protected:
88 friend class ResourceMark;
89 friend class HandleMark;
90 friend class NoHandleMark;
91 Chunk *_first; // First chunk
92 Chunk *_chunk; // current chunk
93 char *_hwm, *_max; // High water mark and max in current chunk
94 void* grow(size_t x); // Get a new Chunk of at least size x
95 size_t _size_in_bytes; // Size of arena (used for memory usage tracing)
96 public:
97 Arena();
98 Arena(size_t init_size);
99 Arena(Arena *old);
100 ~Arena() { _first->chop(); }
101 char* hwm() const { return _hwm; }
102
103 // Fast allocate in the arena. Common case is: pointer test + increment.
104 void* Amalloc(size_t x) {
105 #ifdef _LP64
106 x = (x + (8-1)) & ((unsigned)(-8));
107 #else
108 x = (x + (4-1)) & ((unsigned)(-4));
109 #endif
110 if (_hwm + x > _max) {
111 return grow(x);
112 } else {
113 char *old = _hwm;
114 _hwm += x;
115 return old;
116 }
117 }
118 // Further assume size is padded out to words
119 // Warning: in LP64, Amalloc_4 is really Amalloc_8
120 void *Amalloc_4(size_t x) {
121 assert( (x&(sizeof(char*)-1)) == 0, "misaligned size" );
122 if (_hwm + x > _max) {
123 return grow(x);
124 } else {
125 char *old = _hwm;
126 _hwm += x;
127 return old;
128 }
129 }
130
131 // Fast delete in area. Common case is: NOP (except for storage reclaimed)
132 void Afree(void *ptr, size_t size) {
133 if (((char*)ptr) + size == _hwm) _hwm = (char*)ptr;
134 }
135
136 void *Acalloc( size_t items, size_t x );
137 void *Arealloc( void *old_ptr, size_t old_size, size_t new_size );
138
139 // Reset this Arena to empty, and return this Arenas guts in a new Arena.
140 Arena *reset(void);
141
142 // Determine if pointer belongs to this Arena or not.
143 bool contains( const void *ptr ) const;
144
145 // Total of all chunks in use (not thread-safe)
146 size_t used() const;
147
148 // Total # of bytes used
149 size_t size_in_bytes() const { return _size_in_bytes; }
150 void set_size_in_bytes(size_t size) { _size_in_bytes = size; }
151 };
152
153 #endif // SHARE_VM_ADLC_ARENA_HPP