1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/utilities/sizes.hpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,144 @@
1.4 +/*
1.5 + * Copyright 2000-2004 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +// The following two classes are used to represent 'sizes' and 'offsets' in the VM;
1.29 +// they serve as 'unit' types. ByteSize is used for sizes measured in bytes, while
1.30 +// WordSize is used for sizes measured in machine words (i.e., 32bit or 64bit words
1.31 +// depending on platform).
1.32 +//
1.33 +// The classes are defined with friend functions operating on them instead of member
1.34 +// functions so that they (the classes) can be re-#define'd to int types in optimized
1.35 +// mode. This allows full type checking and maximum safety in debug mode, and full
1.36 +// optimizations (constant folding) and zero overhead (time and space wise) in the
1.37 +// optimized build (some compilers do not optimize one-element value classes but
1.38 +// instead create an object in memory - thus the overhead may be significant).
1.39 +//
1.40 +// Note: 1) DO NOT add new overloaded friend functions that do not have a unique function
1.41 +// function name but require signature types for resolution. This will not work
1.42 +// in optimized mode as both, ByteSize and WordSize are mapped to the same type
1.43 +// and thus the distinction would not be possible anymore (=> compiler errors).
1.44 +//
1.45 +// 2) DO NOT add non-static member functions as they cannot be mapped so something
1.46 +// compilable in the optimized build. Static member functions could be added
1.47 +// but require a corresponding class definition in the optimized build.
1.48 +//
1.49 +// These classes should help doing a transition from (currently) word-size based offsets
1.50 +// to byte-size based offsets in the VM (this will be important if we desire to pack
1.51 +// objects more densely in the VM for 64bit machines). Such a transition should proceed
1.52 +// in two steps to minimize the risk of introducing hard-to-find bugs:
1.53 +//
1.54 +// a) first transition the whole VM into a form where all sizes are strongly typed
1.55 +// b) change all WordSize's to ByteSize's where desired and fix the compilation errors
1.56 +
1.57 +
1.58 +#ifdef ASSERT
1.59 +
1.60 +class ByteSize VALUE_OBJ_CLASS_SPEC {
1.61 + private:
1.62 + int _size;
1.63 +
1.64 + // Note: This constructor must be private to avoid implicit conversions!
1.65 + ByteSize(int size) { _size = size; }
1.66 +
1.67 + public:
1.68 + // constructors
1.69 + inline friend ByteSize in_ByteSize(int size);
1.70 +
1.71 + // accessors
1.72 + inline friend int in_bytes(ByteSize x);
1.73 +
1.74 + // operators
1.75 + friend ByteSize operator + (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) + in_bytes(y)); }
1.76 + friend ByteSize operator - (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) - in_bytes(y)); }
1.77 + friend ByteSize operator * (ByteSize x, int y) { return ByteSize(in_bytes(x) * y ); }
1.78 +
1.79 + // comparison
1.80 + friend bool operator == (ByteSize x, ByteSize y) { return in_bytes(x) == in_bytes(y); }
1.81 + friend bool operator != (ByteSize x, ByteSize y) { return in_bytes(x) != in_bytes(y); }
1.82 + friend bool operator < (ByteSize x, ByteSize y) { return in_bytes(x) < in_bytes(y); }
1.83 + friend bool operator <= (ByteSize x, ByteSize y) { return in_bytes(x) <= in_bytes(y); }
1.84 + friend bool operator > (ByteSize x, ByteSize y) { return in_bytes(x) > in_bytes(y); }
1.85 + friend bool operator >= (ByteSize x, ByteSize y) { return in_bytes(x) >= in_bytes(y); }
1.86 +};
1.87 +
1.88 +inline ByteSize in_ByteSize(int size) { return ByteSize(size); }
1.89 +inline int in_bytes(ByteSize x) { return x._size; }
1.90 +
1.91 +
1.92 +class WordSize VALUE_OBJ_CLASS_SPEC {
1.93 + private:
1.94 + int _size;
1.95 +
1.96 + // Note: This constructor must be private to avoid implicit conversions!
1.97 + WordSize(int size) { _size = size; }
1.98 +
1.99 + public:
1.100 + // constructors
1.101 + inline friend WordSize in_WordSize(int size);
1.102 +
1.103 + // accessors
1.104 + inline friend int in_words(WordSize x);
1.105 +
1.106 + // operators
1.107 + friend WordSize operator + (WordSize x, WordSize y) { return WordSize(in_words(x) + in_words(y)); }
1.108 + friend WordSize operator - (WordSize x, WordSize y) { return WordSize(in_words(x) - in_words(y)); }
1.109 + friend WordSize operator * (WordSize x, int y) { return WordSize(in_words(x) * y ); }
1.110 +
1.111 + // comparison
1.112 + friend bool operator == (WordSize x, WordSize y) { return in_words(x) == in_words(y); }
1.113 + friend bool operator != (WordSize x, WordSize y) { return in_words(x) != in_words(y); }
1.114 + friend bool operator < (WordSize x, WordSize y) { return in_words(x) < in_words(y); }
1.115 + friend bool operator <= (WordSize x, WordSize y) { return in_words(x) <= in_words(y); }
1.116 + friend bool operator > (WordSize x, WordSize y) { return in_words(x) > in_words(y); }
1.117 + friend bool operator >= (WordSize x, WordSize y) { return in_words(x) >= in_words(y); }
1.118 +};
1.119 +
1.120 +inline WordSize in_WordSize(int size) { return WordSize(size); }
1.121 +inline int in_words(WordSize x) { return x._size; }
1.122 +
1.123 +
1.124 +#else // ASSERT
1.125 +
1.126 +// The following definitions must match the corresponding friend declarations
1.127 +// in the Byte/WordSize classes if they are typedef'ed to be int. This will
1.128 +// be the case in optimized mode to ensure zero overhead for these types.
1.129 +//
1.130 +// Note: If a compiler does not inline these function calls away, one may
1.131 +// want to use #define's to make sure full optimization (constant
1.132 +// folding in particular) is possible.
1.133 +
1.134 +typedef int ByteSize;
1.135 +inline ByteSize in_ByteSize(int size) { return size; }
1.136 +inline int in_bytes (ByteSize x) { return x; }
1.137 +
1.138 +typedef int WordSize;
1.139 +inline WordSize in_WordSize(int size) { return size; }
1.140 +inline int in_words (WordSize x) { return x; }
1.141 +
1.142 +#endif // ASSERT
1.143 +
1.144 +
1.145 +// Use the following #define to get C++ field member offsets
1.146 +
1.147 +#define byte_offset_of(klass,field) in_ByteSize((int)offset_of(klass, field))
