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src/share/vm/utilities/sizes.hpp@710a3c8b516e (annotated)

src/share/vm/utilities/sizes.hpp

Tue, 08 Aug 2017 15:57:29 +0800

author

aoqi

date

Tue, 08 Aug 2017 15:57:29 +0800

changeset 6876

710a3c8b516e

parent 2314

f95d63e2154a

parent 0

f90c822e73f8

permissions

-rw-r--r--

merge

aoqi@0	1	/*
aoqi@0	2	* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
aoqi@0	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0	4	*
aoqi@0	5	* This code is free software; you can redistribute it and/or modify it
aoqi@0	6	* under the terms of the GNU General Public License version 2 only, as
aoqi@0	7	* published by the Free Software Foundation.
aoqi@0	8	*
aoqi@0	9	* This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
aoqi@0	12	* version 2 for more details (a copy is included in the LICENSE file that
aoqi@0	13	* accompanied this code).
aoqi@0	14	*
aoqi@0	15	* You should have received a copy of the GNU General Public License version
aoqi@0	16	* 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0	18	*
aoqi@0	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0	20	* or visit www.oracle.com if you need additional information or have any
aoqi@0	21	* questions.
aoqi@0	22	*
aoqi@0	23	*/
aoqi@0	24
aoqi@0	25	#ifndef SHARE_VM_UTILITIES_SIZES_HPP
aoqi@0	26	#define SHARE_VM_UTILITIES_SIZES_HPP
aoqi@0	27
aoqi@0	28	#include "memory/allocation.hpp"
aoqi@0	29	#include "utilities/globalDefinitions.hpp"
aoqi@0	30
aoqi@0	31	// The following two classes are used to represent 'sizes' and 'offsets' in the VM;
aoqi@0	32	// they serve as 'unit' types. ByteSize is used for sizes measured in bytes, while
aoqi@0	33	// WordSize is used for sizes measured in machine words (i.e., 32bit or 64bit words
aoqi@0	34	// depending on platform).
aoqi@0	35	//
aoqi@0	36	// The classes are defined with friend functions operating on them instead of member
aoqi@0	37	// functions so that they (the classes) can be re-#define'd to int types in optimized
aoqi@0	38	// mode. This allows full type checking and maximum safety in debug mode, and full
aoqi@0	39	// optimizations (constant folding) and zero overhead (time and space wise) in the
aoqi@0	40	// optimized build (some compilers do not optimize one-element value classes but
aoqi@0	41	// instead create an object in memory - thus the overhead may be significant).
aoqi@0	42	//
aoqi@0	43	// Note: 1) DO NOT add new overloaded friend functions that do not have a unique function
aoqi@0	44	// function name but require signature types for resolution. This will not work
aoqi@0	45	// in optimized mode as both, ByteSize and WordSize are mapped to the same type
aoqi@0	46	// and thus the distinction would not be possible anymore (=> compiler errors).
aoqi@0	47	//
aoqi@0	48	// 2) DO NOT add non-static member functions as they cannot be mapped so something
aoqi@0	49	// compilable in the optimized build. Static member functions could be added
aoqi@0	50	// but require a corresponding class definition in the optimized build.
aoqi@0	51	//
aoqi@0	52	// These classes should help doing a transition from (currently) word-size based offsets
aoqi@0	53	// to byte-size based offsets in the VM (this will be important if we desire to pack
aoqi@0	54	// objects more densely in the VM for 64bit machines). Such a transition should proceed
aoqi@0	55	// in two steps to minimize the risk of introducing hard-to-find bugs:
aoqi@0	56	//
aoqi@0	57	// a) first transition the whole VM into a form where all sizes are strongly typed
aoqi@0	58	// b) change all WordSize's to ByteSize's where desired and fix the compilation errors
aoqi@0	59
aoqi@0	60
aoqi@0	61	#ifdef ASSERT
aoqi@0	62
aoqi@0	63	class ByteSize VALUE_OBJ_CLASS_SPEC {
aoqi@0	64	private:
aoqi@0	65	int _size;
aoqi@0	66
aoqi@0	67	// Note: This constructor must be private to avoid implicit conversions!
aoqi@0	68	ByteSize(int size) { _size = size; }
aoqi@0	69
aoqi@0	70	public:
aoqi@0	71	// constructors
aoqi@0	72	inline friend ByteSize in_ByteSize(int size);
aoqi@0	73
aoqi@0	74	// accessors
aoqi@0	75	inline friend int in_bytes(ByteSize x);
aoqi@0	76
aoqi@0	77	// operators
aoqi@0	78	friend ByteSize operator + (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) + in_bytes(y)); }
aoqi@0	79	friend ByteSize operator - (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) - in_bytes(y)); }
aoqi@0	80	friend ByteSize operator * (ByteSize x, int y) { return ByteSize(in_bytes(x) * y ); }
aoqi@0	81
aoqi@0	82	// comparison
aoqi@0	83	friend bool operator == (ByteSize x, ByteSize y) { return in_bytes(x) == in_bytes(y); }
aoqi@0	84	friend bool operator != (ByteSize x, ByteSize y) { return in_bytes(x) != in_bytes(y); }
aoqi@0	85	friend bool operator < (ByteSize x, ByteSize y) { return in_bytes(x) < in_bytes(y); }
aoqi@0	86	friend bool operator <= (ByteSize x, ByteSize y) { return in_bytes(x) <= in_bytes(y); }
aoqi@0	87	friend bool operator > (ByteSize x, ByteSize y) { return in_bytes(x) > in_bytes(y); }
aoqi@0	88	friend bool operator >= (ByteSize x, ByteSize y) { return in_bytes(x) >= in_bytes(y); }
aoqi@0	89	};
aoqi@0	90
aoqi@0	91	inline ByteSize in_ByteSize(int size) { return ByteSize(size); }
aoqi@0	92	inline int in_bytes(ByteSize x) { return x._size; }
aoqi@0	93
aoqi@0	94
aoqi@0	95	class WordSize VALUE_OBJ_CLASS_SPEC {
aoqi@0	96	private:
aoqi@0	97	int _size;
aoqi@0	98
aoqi@0	99	// Note: This constructor must be private to avoid implicit conversions!
aoqi@0	100	WordSize(int size) { _size = size; }
aoqi@0	101
aoqi@0	102	public:
aoqi@0	103	// constructors
aoqi@0	104	inline friend WordSize in_WordSize(int size);
aoqi@0	105
aoqi@0	106	// accessors
aoqi@0	107	inline friend int in_words(WordSize x);
aoqi@0	108
aoqi@0	109	// operators
aoqi@0	110	friend WordSize operator + (WordSize x, WordSize y) { return WordSize(in_words(x) + in_words(y)); }
aoqi@0	111	friend WordSize operator - (WordSize x, WordSize y) { return WordSize(in_words(x) - in_words(y)); }
aoqi@0	112	friend WordSize operator * (WordSize x, int y) { return WordSize(in_words(x) * y ); }
aoqi@0	113
aoqi@0	114	// comparison
aoqi@0	115	friend bool operator == (WordSize x, WordSize y) { return in_words(x) == in_words(y); }
aoqi@0	116	friend bool operator != (WordSize x, WordSize y) { return in_words(x) != in_words(y); }
aoqi@0	117	friend bool operator < (WordSize x, WordSize y) { return in_words(x) < in_words(y); }
aoqi@0	118	friend bool operator <= (WordSize x, WordSize y) { return in_words(x) <= in_words(y); }
aoqi@0	119	friend bool operator > (WordSize x, WordSize y) { return in_words(x) > in_words(y); }
aoqi@0	120	friend bool operator >= (WordSize x, WordSize y) { return in_words(x) >= in_words(y); }
aoqi@0	121	};
aoqi@0	122
aoqi@0	123	inline WordSize in_WordSize(int size) { return WordSize(size); }
aoqi@0	124	inline int in_words(WordSize x) { return x._size; }
aoqi@0	125
aoqi@0	126
aoqi@0	127	#else // ASSERT
aoqi@0	128
aoqi@0	129	// The following definitions must match the corresponding friend declarations
aoqi@0	130	// in the Byte/WordSize classes if they are typedef'ed to be int. This will
aoqi@0	131	// be the case in optimized mode to ensure zero overhead for these types.
aoqi@0	132	//
aoqi@0	133	// Note: If a compiler does not inline these function calls away, one may
aoqi@0	134	// want to use #define's to make sure full optimization (constant
aoqi@0	135	// folding in particular) is possible.
aoqi@0	136
aoqi@0	137	typedef int ByteSize;
aoqi@0	138	inline ByteSize in_ByteSize(int size) { return size; }
aoqi@0	139	inline int in_bytes (ByteSize x) { return x; }
aoqi@0	140
aoqi@0	141	typedef int WordSize;
aoqi@0	142	inline WordSize in_WordSize(int size) { return size; }
aoqi@0	143	inline int in_words (WordSize x) { return x; }
aoqi@0	144
aoqi@0	145	#endif // ASSERT
aoqi@0	146
aoqi@0	147
aoqi@0	148	// Use the following #define to get C++ field member offsets
aoqi@0	149
aoqi@0	150	#define byte_offset_of(klass,field) in_ByteSize((int)offset_of(klass, field))
aoqi@0	151
aoqi@0	152	#endif // SHARE_VM_UTILITIES_SIZES_HPP