1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/utilities/sizes.hpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,152 @@
1.4 +/*
1.5 + * Copyright (c) 2000, 2010, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#ifndef SHARE_VM_UTILITIES_SIZES_HPP
1.29 +#define SHARE_VM_UTILITIES_SIZES_HPP
1.30 +
1.31 +#include "memory/allocation.hpp"
1.32 +#include "utilities/globalDefinitions.hpp"
1.33 +
1.34 +// The following two classes are used to represent 'sizes' and 'offsets' in the VM;
1.35 +// they serve as 'unit' types. ByteSize is used for sizes measured in bytes, while
1.36 +// WordSize is used for sizes measured in machine words (i.e., 32bit or 64bit words
1.37 +// depending on platform).
1.38 +//
1.39 +// The classes are defined with friend functions operating on them instead of member
1.40 +// functions so that they (the classes) can be re-#define'd to int types in optimized
1.41 +// mode. This allows full type checking and maximum safety in debug mode, and full
1.42 +// optimizations (constant folding) and zero overhead (time and space wise) in the
1.43 +// optimized build (some compilers do not optimize one-element value classes but
1.44 +// instead create an object in memory - thus the overhead may be significant).
1.45 +//
1.46 +// Note: 1) DO NOT add new overloaded friend functions that do not have a unique function
1.47 +// function name but require signature types for resolution. This will not work
1.48 +// in optimized mode as both, ByteSize and WordSize are mapped to the same type
1.49 +// and thus the distinction would not be possible anymore (=> compiler errors).
1.50 +//
1.51 +// 2) DO NOT add non-static member functions as they cannot be mapped so something
1.52 +// compilable in the optimized build. Static member functions could be added
1.53 +// but require a corresponding class definition in the optimized build.
1.54 +//
1.55 +// These classes should help doing a transition from (currently) word-size based offsets
1.56 +// to byte-size based offsets in the VM (this will be important if we desire to pack
1.57 +// objects more densely in the VM for 64bit machines). Such a transition should proceed
1.58 +// in two steps to minimize the risk of introducing hard-to-find bugs:
1.59 +//
1.60 +// a) first transition the whole VM into a form where all sizes are strongly typed
1.61 +// b) change all WordSize's to ByteSize's where desired and fix the compilation errors
1.62 +
1.63 +
1.64 +#ifdef ASSERT
1.65 +
1.66 +class ByteSize VALUE_OBJ_CLASS_SPEC {
1.67 + private:
1.68 + int _size;
1.69 +
1.70 + // Note: This constructor must be private to avoid implicit conversions!
1.71 + ByteSize(int size) { _size = size; }
1.72 +
1.73 + public:
1.74 + // constructors
1.75 + inline friend ByteSize in_ByteSize(int size);
1.76 +
1.77 + // accessors
1.78 + inline friend int in_bytes(ByteSize x);
1.79 +
1.80 + // operators
1.81 + friend ByteSize operator + (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) + in_bytes(y)); }
1.82 + friend ByteSize operator - (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) - in_bytes(y)); }
1.83 + friend ByteSize operator * (ByteSize x, int y) { return ByteSize(in_bytes(x) * y ); }
1.84 +
1.85 + // comparison
1.86 + friend bool operator == (ByteSize x, ByteSize y) { return in_bytes(x) == in_bytes(y); }
1.87 + friend bool operator != (ByteSize x, ByteSize y) { return in_bytes(x) != in_bytes(y); }
1.88 + friend bool operator < (ByteSize x, ByteSize y) { return in_bytes(x) < in_bytes(y); }
1.89 + friend bool operator <= (ByteSize x, ByteSize y) { return in_bytes(x) <= in_bytes(y); }
1.90 + friend bool operator > (ByteSize x, ByteSize y) { return in_bytes(x) > in_bytes(y); }
1.91 + friend bool operator >= (ByteSize x, ByteSize y) { return in_bytes(x) >= in_bytes(y); }
1.92 +};
1.93 +
1.94 +inline ByteSize in_ByteSize(int size) { return ByteSize(size); }
1.95 +inline int in_bytes(ByteSize x) { return x._size; }
1.96 +
1.97 +
1.98 +class WordSize VALUE_OBJ_CLASS_SPEC {
1.99 + private:
1.100 + int _size;
1.101 +
1.102 + // Note: This constructor must be private to avoid implicit conversions!
1.103 + WordSize(int size) { _size = size; }
1.104 +
1.105 + public:
1.106 + // constructors
1.107 + inline friend WordSize in_WordSize(int size);
1.108 +
1.109 + // accessors
1.110 + inline friend int in_words(WordSize x);
1.111 +
1.112 + // operators
1.113 + friend WordSize operator + (WordSize x, WordSize y) { return WordSize(in_words(x) + in_words(y)); }
1.114 + friend WordSize operator - (WordSize x, WordSize y) { return WordSize(in_words(x) - in_words(y)); }
1.115 + friend WordSize operator * (WordSize x, int y) { return WordSize(in_words(x) * y ); }
1.116 +
1.117 + // comparison
1.118 + friend bool operator == (WordSize x, WordSize y) { return in_words(x) == in_words(y); }
1.119 + friend bool operator != (WordSize x, WordSize y) { return in_words(x) != in_words(y); }
1.120 + friend bool operator < (WordSize x, WordSize y) { return in_words(x) < in_words(y); }
1.121 + friend bool operator <= (WordSize x, WordSize y) { return in_words(x) <= in_words(y); }
1.122 + friend bool operator > (WordSize x, WordSize y) { return in_words(x) > in_words(y); }
1.123 + friend bool operator >= (WordSize x, WordSize y) { return in_words(x) >= in_words(y); }
1.124 +};
1.125 +
1.126 +inline WordSize in_WordSize(int size) { return WordSize(size); }
1.127 +inline int in_words(WordSize x) { return x._size; }
1.128 +
1.129 +
1.130 +#else // ASSERT
1.131 +
1.132 +// The following definitions must match the corresponding friend declarations
1.133 +// in the Byte/WordSize classes if they are typedef'ed to be int. This will
1.134 +// be the case in optimized mode to ensure zero overhead for these types.
1.135 +//
1.136 +// Note: If a compiler does not inline these function calls away, one may
1.137 +// want to use #define's to make sure full optimization (constant
1.138 +// folding in particular) is possible.
1.139 +
1.140 +typedef int ByteSize;
1.141 +inline ByteSize in_ByteSize(int size) { return size; }
1.142 +inline int in_bytes (ByteSize x) { return x; }
1.143 +
1.144 +typedef int WordSize;
1.145 +inline WordSize in_WordSize(int size) { return size; }
1.146 +inline int in_words (WordSize x) { return x; }
1.147 +
1.148 +#endif // ASSERT
1.149 +
1.150 +
1.151 +// Use the following #define to get C++ field member offsets
1.152 +
1.153 +#define byte_offset_of(klass,field) in_ByteSize((int)offset_of(klass, field))
1.154 +
1.155 +#endif // SHARE_VM_UTILITIES_SIZES_HPP
