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src/share/vm/utilities/sizes.hpp@c18cbe5936b8 (annotated)

src/share/vm/utilities/sizes.hpp

Thu, 27 May 2010 19:08:38 -0700

author

trims

date

Thu, 27 May 2010 19:08:38 -0700

changeset 1907

c18cbe5936b8

parent 435

a61af66fc99e

child 2314

f95d63e2154a

permissions

-rw-r--r--

6941466: Oracle rebranding changes for Hotspot repositories
Summary: Change all the Sun copyrights to Oracle copyright
Reviewed-by: ohair

duke@435	1	/*
trims@1907	2	* Copyright (c) 2000, 2004, Oracle and/or its affiliates. All rights reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
trims@1907	19	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907	20	* or visit www.oracle.com if you need additional information or have any
trims@1907	21	* questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	// The following two classes are used to represent 'sizes' and 'offsets' in the VM;
duke@435	26	// they serve as 'unit' types. ByteSize is used for sizes measured in bytes, while
duke@435	27	// WordSize is used for sizes measured in machine words (i.e., 32bit or 64bit words
duke@435	28	// depending on platform).
duke@435	29	//
duke@435	30	// The classes are defined with friend functions operating on them instead of member
duke@435	31	// functions so that they (the classes) can be re-#define'd to int types in optimized
duke@435	32	// mode. This allows full type checking and maximum safety in debug mode, and full
duke@435	33	// optimizations (constant folding) and zero overhead (time and space wise) in the
duke@435	34	// optimized build (some compilers do not optimize one-element value classes but
duke@435	35	// instead create an object in memory - thus the overhead may be significant).
duke@435	36	//
duke@435	37	// Note: 1) DO NOT add new overloaded friend functions that do not have a unique function
duke@435	38	// function name but require signature types for resolution. This will not work
duke@435	39	// in optimized mode as both, ByteSize and WordSize are mapped to the same type
duke@435	40	// and thus the distinction would not be possible anymore (=> compiler errors).
duke@435	41	//
duke@435	42	// 2) DO NOT add non-static member functions as they cannot be mapped so something
duke@435	43	// compilable in the optimized build. Static member functions could be added
duke@435	44	// but require a corresponding class definition in the optimized build.
duke@435	45	//
duke@435	46	// These classes should help doing a transition from (currently) word-size based offsets
duke@435	47	// to byte-size based offsets in the VM (this will be important if we desire to pack
duke@435	48	// objects more densely in the VM for 64bit machines). Such a transition should proceed
duke@435	49	// in two steps to minimize the risk of introducing hard-to-find bugs:
duke@435	50	//
duke@435	51	// a) first transition the whole VM into a form where all sizes are strongly typed
duke@435	52	// b) change all WordSize's to ByteSize's where desired and fix the compilation errors
duke@435	53
duke@435	54
duke@435	55	#ifdef ASSERT
duke@435	56
duke@435	57	class ByteSize VALUE_OBJ_CLASS_SPEC {
duke@435	58	private:
duke@435	59	int _size;
duke@435	60
duke@435	61	// Note: This constructor must be private to avoid implicit conversions!
duke@435	62	ByteSize(int size) { _size = size; }
duke@435	63
duke@435	64	public:
duke@435	65	// constructors
duke@435	66	inline friend ByteSize in_ByteSize(int size);
duke@435	67
duke@435	68	// accessors
duke@435	69	inline friend int in_bytes(ByteSize x);
duke@435	70
duke@435	71	// operators
duke@435	72	friend ByteSize operator + (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) + in_bytes(y)); }
duke@435	73	friend ByteSize operator - (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) - in_bytes(y)); }
duke@435	74	friend ByteSize operator * (ByteSize x, int y) { return ByteSize(in_bytes(x) * y ); }
duke@435	75
duke@435	76	// comparison
duke@435	77	friend bool operator == (ByteSize x, ByteSize y) { return in_bytes(x) == in_bytes(y); }
duke@435	78	friend bool operator != (ByteSize x, ByteSize y) { return in_bytes(x) != in_bytes(y); }
duke@435	79	friend bool operator < (ByteSize x, ByteSize y) { return in_bytes(x) < in_bytes(y); }
duke@435	80	friend bool operator <= (ByteSize x, ByteSize y) { return in_bytes(x) <= in_bytes(y); }
duke@435	81	friend bool operator > (ByteSize x, ByteSize y) { return in_bytes(x) > in_bytes(y); }
duke@435	82	friend bool operator >= (ByteSize x, ByteSize y) { return in_bytes(x) >= in_bytes(y); }
duke@435	83	};
duke@435	84
duke@435	85	inline ByteSize in_ByteSize(int size) { return ByteSize(size); }
duke@435	86	inline int in_bytes(ByteSize x) { return x._size; }
duke@435	87
duke@435	88
duke@435	89	class WordSize VALUE_OBJ_CLASS_SPEC {
duke@435	90	private:
duke@435	91	int _size;
duke@435	92
duke@435	93	// Note: This constructor must be private to avoid implicit conversions!
duke@435	94	WordSize(int size) { _size = size; }
duke@435	95
duke@435	96	public:
duke@435	97	// constructors
duke@435	98	inline friend WordSize in_WordSize(int size);
duke@435	99
duke@435	100	// accessors
duke@435	101	inline friend int in_words(WordSize x);
duke@435	102
duke@435	103	// operators
duke@435	104	friend WordSize operator + (WordSize x, WordSize y) { return WordSize(in_words(x) + in_words(y)); }
duke@435	105	friend WordSize operator - (WordSize x, WordSize y) { return WordSize(in_words(x) - in_words(y)); }
duke@435	106	friend WordSize operator * (WordSize x, int y) { return WordSize(in_words(x) * y ); }
duke@435	107
duke@435	108	// comparison
duke@435	109	friend bool operator == (WordSize x, WordSize y) { return in_words(x) == in_words(y); }
duke@435	110	friend bool operator != (WordSize x, WordSize y) { return in_words(x) != in_words(y); }
duke@435	111	friend bool operator < (WordSize x, WordSize y) { return in_words(x) < in_words(y); }
duke@435	112	friend bool operator <= (WordSize x, WordSize y) { return in_words(x) <= in_words(y); }
duke@435	113	friend bool operator > (WordSize x, WordSize y) { return in_words(x) > in_words(y); }
duke@435	114	friend bool operator >= (WordSize x, WordSize y) { return in_words(x) >= in_words(y); }
duke@435	115	};
duke@435	116
duke@435	117	inline WordSize in_WordSize(int size) { return WordSize(size); }
duke@435	118	inline int in_words(WordSize x) { return x._size; }
duke@435	119
duke@435	120
duke@435	121	#else // ASSERT
duke@435	122
duke@435	123	// The following definitions must match the corresponding friend declarations
duke@435	124	// in the Byte/WordSize classes if they are typedef'ed to be int. This will
duke@435	125	// be the case in optimized mode to ensure zero overhead for these types.
duke@435	126	//
duke@435	127	// Note: If a compiler does not inline these function calls away, one may
duke@435	128	// want to use #define's to make sure full optimization (constant
duke@435	129	// folding in particular) is possible.
duke@435	130
duke@435	131	typedef int ByteSize;
duke@435	132	inline ByteSize in_ByteSize(int size) { return size; }
duke@435	133	inline int in_bytes (ByteSize x) { return x; }
duke@435	134
duke@435	135	typedef int WordSize;
duke@435	136	inline WordSize in_WordSize(int size) { return size; }
duke@435	137	inline int in_words (WordSize x) { return x; }
duke@435	138
duke@435	139	#endif // ASSERT
duke@435	140
duke@435	141
duke@435	142	// Use the following #define to get C++ field member offsets
duke@435	143
duke@435	144	#define byte_offset_of(klass,field) in_ByteSize((int)offset_of(klass, field))