| /* |
| * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
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| * |
| */ |
| |
| #ifndef SHARE_VM_UTILITIES_SIZES_HPP |
| #define SHARE_VM_UTILITIES_SIZES_HPP |
| |
| #include "memory/allocation.hpp" |
| #include "utilities/globalDefinitions.hpp" |
| |
| // The following two classes are used to represent 'sizes' and 'offsets' in the VM; |
| // they serve as 'unit' types. ByteSize is used for sizes measured in bytes, while |
| // WordSize is used for sizes measured in machine words (i.e., 32bit or 64bit words |
| // depending on platform). |
| // |
| // The classes are defined with friend functions operating on them instead of member |
| // functions so that they (the classes) can be re-#define'd to int types in optimized |
| // mode. This allows full type checking and maximum safety in debug mode, and full |
| // optimizations (constant folding) and zero overhead (time and space wise) in the |
| // optimized build (some compilers do not optimize one-element value classes but |
| // instead create an object in memory - thus the overhead may be significant). |
| // |
| // Note: 1) DO NOT add new overloaded friend functions that do not have a unique function |
| // function name but require signature types for resolution. This will not work |
| // in optimized mode as both, ByteSize and WordSize are mapped to the same type |
| // and thus the distinction would not be possible anymore (=> compiler errors). |
| // |
| // 2) DO NOT add non-static member functions as they cannot be mapped so something |
| // compilable in the optimized build. Static member functions could be added |
| // but require a corresponding class definition in the optimized build. |
| // |
| // These classes should help doing a transition from (currently) word-size based offsets |
| // to byte-size based offsets in the VM (this will be important if we desire to pack |
| // objects more densely in the VM for 64bit machines). Such a transition should proceed |
| // in two steps to minimize the risk of introducing hard-to-find bugs: |
| // |
| // a) first transition the whole VM into a form where all sizes are strongly typed |
| // b) change all WordSize's to ByteSize's where desired and fix the compilation errors |
| |
| |
| #ifdef ASSERT |
| |
| class ByteSize VALUE_OBJ_CLASS_SPEC { |
| private: |
| int _size; |
| |
| // Note: This constructor must be private to avoid implicit conversions! |
| ByteSize(int size) { _size = size; } |
| |
| public: |
| // constructors |
| inline friend ByteSize in_ByteSize(int size); |
| |
| // accessors |
| inline friend int in_bytes(ByteSize x); |
| |
| // operators |
| friend ByteSize operator + (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) + in_bytes(y)); } |
| friend ByteSize operator - (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) - in_bytes(y)); } |
| friend ByteSize operator * (ByteSize x, int y) { return ByteSize(in_bytes(x) * y ); } |
| |
| // comparison |
| friend bool operator == (ByteSize x, ByteSize y) { return in_bytes(x) == in_bytes(y); } |
| friend bool operator != (ByteSize x, ByteSize y) { return in_bytes(x) != in_bytes(y); } |
| friend bool operator < (ByteSize x, ByteSize y) { return in_bytes(x) < in_bytes(y); } |
| friend bool operator <= (ByteSize x, ByteSize y) { return in_bytes(x) <= in_bytes(y); } |
| friend bool operator > (ByteSize x, ByteSize y) { return in_bytes(x) > in_bytes(y); } |
| friend bool operator >= (ByteSize x, ByteSize y) { return in_bytes(x) >= in_bytes(y); } |
| }; |
| |
| inline ByteSize in_ByteSize(int size) { return ByteSize(size); } |
| inline int in_bytes(ByteSize x) { return x._size; } |
| |
| |
| class WordSize VALUE_OBJ_CLASS_SPEC { |
| private: |
| int _size; |
| |
| // Note: This constructor must be private to avoid implicit conversions! |
| WordSize(int size) { _size = size; } |
| |
| public: |
| // constructors |
| inline friend WordSize in_WordSize(int size); |
| |
| // accessors |
| inline friend int in_words(WordSize x); |
| |
| // operators |
| friend WordSize operator + (WordSize x, WordSize y) { return WordSize(in_words(x) + in_words(y)); } |
| friend WordSize operator - (WordSize x, WordSize y) { return WordSize(in_words(x) - in_words(y)); } |
| friend WordSize operator * (WordSize x, int y) { return WordSize(in_words(x) * y ); } |
| |
| // comparison |
| friend bool operator == (WordSize x, WordSize y) { return in_words(x) == in_words(y); } |
| friend bool operator != (WordSize x, WordSize y) { return in_words(x) != in_words(y); } |
| friend bool operator < (WordSize x, WordSize y) { return in_words(x) < in_words(y); } |
| friend bool operator <= (WordSize x, WordSize y) { return in_words(x) <= in_words(y); } |
| friend bool operator > (WordSize x, WordSize y) { return in_words(x) > in_words(y); } |
| friend bool operator >= (WordSize x, WordSize y) { return in_words(x) >= in_words(y); } |
| }; |
| |
| inline WordSize in_WordSize(int size) { return WordSize(size); } |
| inline int in_words(WordSize x) { return x._size; } |
| |
| |
| #else // ASSERT |
| |
| // The following definitions must match the corresponding friend declarations |
| // in the Byte/WordSize classes if they are typedef'ed to be int. This will |
| // be the case in optimized mode to ensure zero overhead for these types. |
| // |
| // Note: If a compiler does not inline these function calls away, one may |
| // want to use #define's to make sure full optimization (constant |
| // folding in particular) is possible. |
| |
| typedef int ByteSize; |
| inline ByteSize in_ByteSize(int size) { return size; } |
| inline int in_bytes (ByteSize x) { return x; } |
| |
| typedef int WordSize; |
| inline WordSize in_WordSize(int size) { return size; } |
| inline int in_words (WordSize x) { return x; } |
| |
| #endif // ASSERT |
| |
| |
| // Use the following #define to get C++ field member offsets |
| |
| #define byte_offset_of(klass,field) in_ByteSize((int)offset_of(klass, field)) |
| |
| #endif // SHARE_VM_UTILITIES_SIZES_HPP |