Gitly


1 /*
2  * Copyright (c) 1999-2005 Hewlett-Packard Development Company, L.P.
3  *
4  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
5  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
6  *
7  * Permission is hereby granted to use or copy this program
8  * for any purpose, provided the above notices are retained on all copies.
9  * Permission to modify the code and to distribute modified code is granted,
10  * provided the above notices are retained, and a notice that the code was
11  * modified is included with the above copyright notice.
12  */
13 
14 #ifndef GC_TINY_FL_H
15 #define GC_TINY_FL_H
16 
17 /*
18  * Constants and data structures for "tiny" free lists.
19  * These are used for thread-local allocation and inlined allocators.
20  * Each global free list also essentially starts with one of these.
21  * However, global free lists are known to the collector.
22  * "Tiny" free lists are basically private to the client.
23  * Their contents are viewed as "in use" and marked accordingly by the
24  * core of the collector.  Note that inlined code might know about the
25  * layout of these and the constants involved.  Thus any change here
26  * may invalidate clients, and such changes should be avoided.
27  * Hence we keep this as simple as possible.
28  */
29 
30 /*
31  * We always set `GC_GRANULE_BYTES` to twice the length of a pointer.
32  * This means that all allocation requests are rounded up to the next
33  * multiple of 16 on 64-bit architectures or 8 on 32-bit architectures.
34  * This appears to be a reasonable compromise between fragmentation
35  * overhead and space usage for mark bits (usually mark bytes).
36  * On many 64-bit architectures some memory references require 16-byte
37  * alignment, making this necessary anyway.  For a few 32-bit
38  * architectures (e.g. i686), we may also need 16-byte alignment for
39  * certain memory references.  But currently that does not seem to be
40  * the default for all conventional `malloc` implementations, so we
41  * ignore that problem.
42  * It would always be safe, and often useful, to be able to allocate
43  * very small objects with smaller alignment.  But that would cost us
44  * mark bit space, so we no longer do so.
45  * `GC_GRANULE_BYTES` should not be overridden in any instances of the
46  * collector library that may be shared between applications, since it
47  * affects the ABI (application binary interface) to the library.
48  */
49 #if defined(CPPCHECK) && GC_GRANULE_BYTES == 1
50 #  undef GC_GRANULE_BYTES
51 #endif
52 #ifdef GC_GRANULE_BYTES
53 #  define GC_GRANULE_PTRS (GC_GRANULE_BYTES / GC_SIZEOF_PTR)
54 #else
55 #  define GC_GRANULE_PTRS 2 /*< in pointers */
56 #  define GC_GRANULE_BYTES (GC_GRANULE_PTRS * GC_SIZEOF_PTR)
57 #endif /* !GC_GRANULE_BYTES */
58 
59 /** Convert size in pointers to that in granules. */
60 #define GC_PTRS_TO_GRANULES(n) ((n) / GC_GRANULE_PTRS)
61 
62 /**
63  * Convert size in pointers to that in granules, but rounding up the
64  * result.
65  */
66 #define GC_PTRS_TO_WHOLE_GRANULES(n) \
67   GC_PTRS_TO_GRANULES((n) + GC_GRANULE_PTRS - 1)
68 
69 /*
70  * A "tiny" free-list header contains `GC_TINY_FREELISTS` pointers to
71  * singly-linked lists of objects of different sizes, the `i`-th one
72  * containing objects of `i` granules in size.  Note that there is
73  * a list of size zero objects.
74  */
75 #ifndef GC_TINY_FREELISTS
76 #  if GC_GRANULE_BYTES >= 16
77 #    define GC_TINY_FREELISTS 25
78 #  else
79 #    define GC_TINY_FREELISTS 33 /*< up to and including 256 bytes */
80 #  endif
81 #endif /* !GC_TINY_FREELISTS */
82 
83 /*
84  * The `i`-th free list corresponds to size `i * GC_GRANULE_BYTES`.
85  * Internally to the collector, the index `i` can be computed with
86  * `ALLOC_REQUEST_GRANS()`.  The latter also depends on the values
87  * returned by `GC_get_dont_add_byte_at_end()` and
88  * `GC_get_all_interior_pointers()`.
89  */
90 
91 /**
92  * Convert a free-list index to the actual size of objects on that list,
93  * including extra space we added.  Not an inverse of the above.
94  */
95 #define GC_RAW_BYTES_FROM_INDEX(i) (GC_GRANULE_BYTES * (i))
96 
97 /* Deprecated.  Use `GC_GRANULE_PTRS` instead. */
98 #undef GC_GRANULE_WORDS
99 #define GC_GRANULE_WORDS GC_GRANULE_PTRS
100 
101 /* Deprecated.  Use `GC_PTRS_TO_GRANULES()` instead. */
102 #define GC_WORDS_TO_GRANULES(n) GC_PTRS_TO_GRANULES(n)
103 
104 /* Deprecated. */
105 #define GC_WORDS_TO_WHOLE_GRANULES(n) GC_PTRS_TO_WHOLE_GRANULES(n)
106 
107 #endif /* GC_TINY_FL_H */
108

1	/*
2	* Copyright (c) 1999-2005 Hewlett-Packard Development Company, L.P.
3	*
4	* THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
5	* OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
6	*
7	* Permission is hereby granted to use or copy this program
8	* for any purpose, provided the above notices are retained on all copies.
9	* Permission to modify the code and to distribute modified code is granted,
10	* provided the above notices are retained, and a notice that the code was
11	* modified is included with the above copyright notice.
12	*/
13
14	#ifndef GC_TINY_FL_H
15	#define GC_TINY_FL_H
16
17	/*
18	* Constants and data structures for "tiny" free lists.
19	* These are used for thread-local allocation and inlined allocators.
20	* Each global free list also essentially starts with one of these.
21	* However, global free lists are known to the collector.
22	* "Tiny" free lists are basically private to the client.
23	* Their contents are viewed as "in use" and marked accordingly by the
24	* core of the collector. Note that inlined code might know about the
25	* layout of these and the constants involved. Thus any change here
26	* may invalidate clients, and such changes should be avoided.
27	* Hence we keep this as simple as possible.
28	*/
29
30	/*
31	* We always set `GC_GRANULE_BYTES` to twice the length of a pointer.
32	* This means that all allocation requests are rounded up to the next
33	* multiple of 16 on 64-bit architectures or 8 on 32-bit architectures.
34	* This appears to be a reasonable compromise between fragmentation
35	* overhead and space usage for mark bits (usually mark bytes).
36	* On many 64-bit architectures some memory references require 16-byte
37	* alignment, making this necessary anyway. For a few 32-bit
38	* architectures (e.g. i686), we may also need 16-byte alignment for
39	* certain memory references. But currently that does not seem to be
40	* the default for all conventional `malloc` implementations, so we
41	* ignore that problem.
42	* It would always be safe, and often useful, to be able to allocate
43	* very small objects with smaller alignment. But that would cost us
44	* mark bit space, so we no longer do so.
45	* `GC_GRANULE_BYTES` should not be overridden in any instances of the
46	* collector library that may be shared between applications, since it
47	* affects the ABI (application binary interface) to the library.
48	*/
49	#if defined(CPPCHECK) && GC_GRANULE_BYTES == 1
50	# undef GC_GRANULE_BYTES
51	#endif
52	#ifdef GC_GRANULE_BYTES
53	# define GC_GRANULE_PTRS (GC_GRANULE_BYTES / GC_SIZEOF_PTR)
54	#else
55	# define GC_GRANULE_PTRS 2 /< in pointers /
56	# define GC_GRANULE_BYTES (GC_GRANULE_PTRS * GC_SIZEOF_PTR)
57	#endif / !GC_GRANULE_BYTES /
58
59	/* Convert size in pointers to that in granules. /
60	#define GC_PTRS_TO_GRANULES(n) ((n) / GC_GRANULE_PTRS)
61
62	/**
63	* Convert size in pointers to that in granules, but rounding up the
64	* result.
65	*/
66	#define GC_PTRS_TO_WHOLE_GRANULES(n) \
67	GC_PTRS_TO_GRANULES((n) + GC_GRANULE_PTRS - 1)
68
69	/*
70	* A "tiny" free-list header contains `GC_TINY_FREELISTS` pointers to
71	* singly-linked lists of objects of different sizes, the `i`-th one
72	* containing objects of `i` granules in size. Note that there is
73	* a list of size zero objects.
74	*/
75	#ifndef GC_TINY_FREELISTS
76	# if GC_GRANULE_BYTES >= 16
77	# define GC_TINY_FREELISTS 25
78	# else
79	# define GC_TINY_FREELISTS 33 /< up to and including 256 bytes /
80	# endif
81	#endif / !GC_TINY_FREELISTS /
82
83	/*
84	* The `i`-th free list corresponds to size `i * GC_GRANULE_BYTES`.
85	* Internally to the collector, the index `i` can be computed with
86	* `ALLOC_REQUEST_GRANS()`. The latter also depends on the values
87	* returned by `GC_get_dont_add_byte_at_end()` and
88	* `GC_get_all_interior_pointers()`.
89	*/
90
91	/**
92	* Convert a free-list index to the actual size of objects on that list,
93	* including extra space we added. Not an inverse of the above.
94	*/
95	#define GC_RAW_BYTES_FROM_INDEX(i) (GC_GRANULE_BYTES * (i))
96
97	/ Deprecated. Use `GC_GRANULE_PTRS` instead. /
98	#undef GC_GRANULE_WORDS
99	#define GC_GRANULE_WORDS GC_GRANULE_PTRS
100
101	/ Deprecated. Use `GC_PTRS_TO_GRANULES()` instead. /
102	#define GC_WORDS_TO_GRANULES(n) GC_PTRS_TO_GRANULES(n)
103
104	/ Deprecated. /
105	#define GC_WORDS_TO_WHOLE_GRANULES(n) GC_PTRS_TO_WHOLE_GRANULES(n)
106
107	#endif / GC_TINY_FL_H /
108