0
|
1 /*
|
|
2 * Copyright 2000-2004 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
|
|
20 * CA 95054 USA or visit www.sun.com if you need additional information or
|
|
21 * have any questions.
|
|
22 *
|
|
23 */
|
|
24
|
|
25 // The following two classes are used to represent 'sizes' and 'offsets' in the VM;
|
|
26 // they serve as 'unit' types. ByteSize is used for sizes measured in bytes, while
|
|
27 // WordSize is used for sizes measured in machine words (i.e., 32bit or 64bit words
|
|
28 // depending on platform).
|
|
29 //
|
|
30 // The classes are defined with friend functions operating on them instead of member
|
|
31 // functions so that they (the classes) can be re-#define'd to int types in optimized
|
|
32 // mode. This allows full type checking and maximum safety in debug mode, and full
|
|
33 // optimizations (constant folding) and zero overhead (time and space wise) in the
|
|
34 // optimized build (some compilers do not optimize one-element value classes but
|
|
35 // instead create an object in memory - thus the overhead may be significant).
|
|
36 //
|
|
37 // Note: 1) DO NOT add new overloaded friend functions that do not have a unique function
|
|
38 // function name but require signature types for resolution. This will not work
|
|
39 // in optimized mode as both, ByteSize and WordSize are mapped to the same type
|
|
40 // and thus the distinction would not be possible anymore (=> compiler errors).
|
|
41 //
|
|
42 // 2) DO NOT add non-static member functions as they cannot be mapped so something
|
|
43 // compilable in the optimized build. Static member functions could be added
|
|
44 // but require a corresponding class definition in the optimized build.
|
|
45 //
|
|
46 // These classes should help doing a transition from (currently) word-size based offsets
|
|
47 // to byte-size based offsets in the VM (this will be important if we desire to pack
|
|
48 // objects more densely in the VM for 64bit machines). Such a transition should proceed
|
|
49 // in two steps to minimize the risk of introducing hard-to-find bugs:
|
|
50 //
|
|
51 // a) first transition the whole VM into a form where all sizes are strongly typed
|
|
52 // b) change all WordSize's to ByteSize's where desired and fix the compilation errors
|
|
53
|
|
54
|
|
55 #ifdef ASSERT
|
|
56
|
|
57 class ByteSize VALUE_OBJ_CLASS_SPEC {
|
|
58 private:
|
|
59 int _size;
|
|
60
|
|
61 // Note: This constructor must be private to avoid implicit conversions!
|
|
62 ByteSize(int size) { _size = size; }
|
|
63
|
|
64 public:
|
|
65 // constructors
|
|
66 inline friend ByteSize in_ByteSize(int size);
|
|
67
|
|
68 // accessors
|
|
69 inline friend int in_bytes(ByteSize x);
|
|
70
|
|
71 // operators
|
|
72 friend ByteSize operator + (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) + in_bytes(y)); }
|
|
73 friend ByteSize operator - (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) - in_bytes(y)); }
|
|
74 friend ByteSize operator * (ByteSize x, int y) { return ByteSize(in_bytes(x) * y ); }
|
|
75
|
|
76 // comparison
|
|
77 friend bool operator == (ByteSize x, ByteSize y) { return in_bytes(x) == in_bytes(y); }
|
|
78 friend bool operator != (ByteSize x, ByteSize y) { return in_bytes(x) != in_bytes(y); }
|
|
79 friend bool operator < (ByteSize x, ByteSize y) { return in_bytes(x) < in_bytes(y); }
|
|
80 friend bool operator <= (ByteSize x, ByteSize y) { return in_bytes(x) <= in_bytes(y); }
|
|
81 friend bool operator > (ByteSize x, ByteSize y) { return in_bytes(x) > in_bytes(y); }
|
|
82 friend bool operator >= (ByteSize x, ByteSize y) { return in_bytes(x) >= in_bytes(y); }
|
|
83 };
|
|
84
|
|
85 inline ByteSize in_ByteSize(int size) { return ByteSize(size); }
|
|
86 inline int in_bytes(ByteSize x) { return x._size; }
|
|
87
|
|
88
|
|
89 class WordSize VALUE_OBJ_CLASS_SPEC {
|
|
90 private:
|
|
91 int _size;
|
|
92
|
|
93 // Note: This constructor must be private to avoid implicit conversions!
|
|
94 WordSize(int size) { _size = size; }
|
|
95
|
|
96 public:
|
|
97 // constructors
|
|
98 inline friend WordSize in_WordSize(int size);
|
|
99
|
|
100 // accessors
|
|
101 inline friend int in_words(WordSize x);
|
|
102
|
|
103 // operators
|
|
104 friend WordSize operator + (WordSize x, WordSize y) { return WordSize(in_words(x) + in_words(y)); }
|
|
105 friend WordSize operator - (WordSize x, WordSize y) { return WordSize(in_words(x) - in_words(y)); }
|
|
106 friend WordSize operator * (WordSize x, int y) { return WordSize(in_words(x) * y ); }
|
|
107
|
|
108 // comparison
|
|
109 friend bool operator == (WordSize x, WordSize y) { return in_words(x) == in_words(y); }
|
|
110 friend bool operator != (WordSize x, WordSize y) { return in_words(x) != in_words(y); }
|
|
111 friend bool operator < (WordSize x, WordSize y) { return in_words(x) < in_words(y); }
|
|
112 friend bool operator <= (WordSize x, WordSize y) { return in_words(x) <= in_words(y); }
|
|
113 friend bool operator > (WordSize x, WordSize y) { return in_words(x) > in_words(y); }
|
|
114 friend bool operator >= (WordSize x, WordSize y) { return in_words(x) >= in_words(y); }
|
|
115 };
|
|
116
|
|
117 inline WordSize in_WordSize(int size) { return WordSize(size); }
|
|
118 inline int in_words(WordSize x) { return x._size; }
|
|
119
|
|
120
|
|
121 #else // ASSERT
|
|
122
|
|
123 // The following definitions must match the corresponding friend declarations
|
|
124 // in the Byte/WordSize classes if they are typedef'ed to be int. This will
|
|
125 // be the case in optimized mode to ensure zero overhead for these types.
|
|
126 //
|
|
127 // Note: If a compiler does not inline these function calls away, one may
|
|
128 // want to use #define's to make sure full optimization (constant
|
|
129 // folding in particular) is possible.
|
|
130
|
|
131 typedef int ByteSize;
|
|
132 inline ByteSize in_ByteSize(int size) { return size; }
|
|
133 inline int in_bytes (ByteSize x) { return x; }
|
|
134
|
|
135 typedef int WordSize;
|
|
136 inline WordSize in_WordSize(int size) { return size; }
|
|
137 inline int in_words (WordSize x) { return x; }
|
|
138
|
|
139 #endif // ASSERT
|
|
140
|
|
141
|
|
142 // Use the following #define to get C++ field member offsets
|
|
143
|
|
144 #define byte_offset_of(klass,field) in_ByteSize((int)offset_of(klass, field))
|