Mercurial > hg > graal-compiler
annotate src/share/vm/utilities/sizes.hpp @ 1711:a6bff45449bc
6973570: OrderAccess::storestore() scales poorly on multi-socket x64 and sparc: cache-line ping-ponging
Summary: volatile store to static variable removed in favour of a volatile store to stack to avoid excessive cache coherency traffic; verified that the volatile store is not elided by any of our current compilers.
Reviewed-by: dholmes, dice, jcoomes, kvn
author | ysr |
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date | Tue, 10 Aug 2010 14:53:35 -0700 |
parents | c18cbe5936b8 |
children | f95d63e2154a |
rev | line source |
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0 | 1 /* |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
25 // The following two classes are used to represent 'sizes' and 'offsets' in the VM; | |
26 // they serve as 'unit' types. ByteSize is used for sizes measured in bytes, while | |
27 // WordSize is used for sizes measured in machine words (i.e., 32bit or 64bit words | |
28 // depending on platform). | |
29 // | |
30 // The classes are defined with friend functions operating on them instead of member | |
31 // functions so that they (the classes) can be re-#define'd to int types in optimized | |
32 // mode. This allows full type checking and maximum safety in debug mode, and full | |
33 // optimizations (constant folding) and zero overhead (time and space wise) in the | |
34 // optimized build (some compilers do not optimize one-element value classes but | |
35 // instead create an object in memory - thus the overhead may be significant). | |
36 // | |
37 // Note: 1) DO NOT add new overloaded friend functions that do not have a unique function | |
38 // function name but require signature types for resolution. This will not work | |
39 // in optimized mode as both, ByteSize and WordSize are mapped to the same type | |
40 // and thus the distinction would not be possible anymore (=> compiler errors). | |
41 // | |
42 // 2) DO NOT add non-static member functions as they cannot be mapped so something | |
43 // compilable in the optimized build. Static member functions could be added | |
44 // but require a corresponding class definition in the optimized build. | |
45 // | |
46 // These classes should help doing a transition from (currently) word-size based offsets | |
47 // to byte-size based offsets in the VM (this will be important if we desire to pack | |
48 // objects more densely in the VM for 64bit machines). Such a transition should proceed | |
49 // in two steps to minimize the risk of introducing hard-to-find bugs: | |
50 // | |
51 // a) first transition the whole VM into a form where all sizes are strongly typed | |
52 // b) change all WordSize's to ByteSize's where desired and fix the compilation errors | |
53 | |
54 | |
55 #ifdef ASSERT | |
56 | |
57 class ByteSize VALUE_OBJ_CLASS_SPEC { | |
58 private: | |
59 int _size; | |
60 | |
61 // Note: This constructor must be private to avoid implicit conversions! | |
62 ByteSize(int size) { _size = size; } | |
63 | |
64 public: | |
65 // constructors | |
66 inline friend ByteSize in_ByteSize(int size); | |
67 | |
68 // accessors | |
69 inline friend int in_bytes(ByteSize x); | |
70 | |
71 // operators | |
72 friend ByteSize operator + (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) + in_bytes(y)); } | |
73 friend ByteSize operator - (ByteSize x, ByteSize y) { return ByteSize(in_bytes(x) - in_bytes(y)); } | |
74 friend ByteSize operator * (ByteSize x, int y) { return ByteSize(in_bytes(x) * y ); } | |
75 | |
76 // comparison | |
77 friend bool operator == (ByteSize x, ByteSize y) { return in_bytes(x) == in_bytes(y); } | |
78 friend bool operator != (ByteSize x, ByteSize y) { return in_bytes(x) != in_bytes(y); } | |
79 friend bool operator < (ByteSize x, ByteSize y) { return in_bytes(x) < in_bytes(y); } | |
80 friend bool operator <= (ByteSize x, ByteSize y) { return in_bytes(x) <= in_bytes(y); } | |
81 friend bool operator > (ByteSize x, ByteSize y) { return in_bytes(x) > in_bytes(y); } | |
82 friend bool operator >= (ByteSize x, ByteSize y) { return in_bytes(x) >= in_bytes(y); } | |
83 }; | |
84 | |
85 inline ByteSize in_ByteSize(int size) { return ByteSize(size); } | |
86 inline int in_bytes(ByteSize x) { return x._size; } | |
87 | |
88 | |
89 class WordSize VALUE_OBJ_CLASS_SPEC { | |
90 private: | |
91 int _size; | |
92 | |
93 // Note: This constructor must be private to avoid implicit conversions! | |
94 WordSize(int size) { _size = size; } | |
95 | |
96 public: | |
97 // constructors | |
98 inline friend WordSize in_WordSize(int size); | |
99 | |
100 // accessors | |
101 inline friend int in_words(WordSize x); | |
102 | |
103 // operators | |
104 friend WordSize operator + (WordSize x, WordSize y) { return WordSize(in_words(x) + in_words(y)); } | |
105 friend WordSize operator - (WordSize x, WordSize y) { return WordSize(in_words(x) - in_words(y)); } | |
106 friend WordSize operator * (WordSize x, int y) { return WordSize(in_words(x) * y ); } | |
107 | |
108 // comparison | |
109 friend bool operator == (WordSize x, WordSize y) { return in_words(x) == in_words(y); } | |
110 friend bool operator != (WordSize x, WordSize y) { return in_words(x) != in_words(y); } | |
111 friend bool operator < (WordSize x, WordSize y) { return in_words(x) < in_words(y); } | |
112 friend bool operator <= (WordSize x, WordSize y) { return in_words(x) <= in_words(y); } | |
113 friend bool operator > (WordSize x, WordSize y) { return in_words(x) > in_words(y); } | |
114 friend bool operator >= (WordSize x, WordSize y) { return in_words(x) >= in_words(y); } | |
115 }; | |
116 | |
117 inline WordSize in_WordSize(int size) { return WordSize(size); } | |
118 inline int in_words(WordSize x) { return x._size; } | |
119 | |
120 | |
121 #else // ASSERT | |
122 | |
123 // The following definitions must match the corresponding friend declarations | |
124 // in the Byte/WordSize classes if they are typedef'ed to be int. This will | |
125 // be the case in optimized mode to ensure zero overhead for these types. | |
126 // | |
127 // Note: If a compiler does not inline these function calls away, one may | |
128 // want to use #define's to make sure full optimization (constant | |
129 // folding in particular) is possible. | |
130 | |
131 typedef int ByteSize; | |
132 inline ByteSize in_ByteSize(int size) { return size; } | |
133 inline int in_bytes (ByteSize x) { return x; } | |
134 | |
135 typedef int WordSize; | |
136 inline WordSize in_WordSize(int size) { return size; } | |
137 inline int in_words (WordSize x) { return x; } | |
138 | |
139 #endif // ASSERT | |
140 | |
141 | |
142 // Use the following #define to get C++ field member offsets | |
143 | |
144 #define byte_offset_of(klass,field) in_ByteSize((int)offset_of(klass, field)) |