libobjc/objc-private/sarray.h

   1 /* Sparse Arrays for Objective C dispatch tables
   2    Copyright (C) 1993, 1995, 1996, 2004, 2009 Free Software Foundation, Inc.
   3    Contributed by Kresten Krab Thorup.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 #ifndef __sarray_INCLUDE_GNU
  27 #define __sarray_INCLUDE_GNU
  28
  29 #define OBJC_SPARSE2            /* 2-level sparse array */
  30 /* #define OBJC_SPARSE3 */      /* 3-level sparse array */
  31
  32 #ifdef OBJC_SPARSE2
  33 extern const char* __objc_sparse2_id;
  34 #endif
  35
  36 #ifdef OBJC_SPARSE3
  37 extern const char* __objc_sparse3_id;
  38 #endif
  39
  40 #include <stddef.h>
  41
  42 #ifdef __cplusplus
  43 extern "C" {
  44 #endif /* __cplusplus */
  45
  46 extern int nbuckets;            /* for stats */
  47 extern int nindices;
  48 extern int narrays;
  49 extern int idxsize;
  50
  51 /* An unsigned integer of same size as a pointer */
  52 #define SIZET_BITS (sizeof(size_t)*8)
  53
  54 #if defined(__sparc__) || defined(OBJC_SPARSE2)
  55 #define PRECOMPUTE_SELECTORS
  56 #endif
  57
  58 #ifdef OBJC_SPARSE3
  59
  60 /* Buckets are 8 words each */
  61 #define BUCKET_BITS 3
  62 #define BUCKET_SIZE (1<<BUCKET_BITS)
  63 #define BUCKET_MASK (BUCKET_SIZE-1)
  64
  65 /* Indices are 16 words each */
  66 #define INDEX_BITS 4
  67 #define INDEX_SIZE (1<<INDEX_BITS)
  68 #define INDEX_MASK (INDEX_SIZE-1)
  69
  70 #define INDEX_CAPACITY (BUCKET_SIZE*INDEX_SIZE)
  71
  72 #else /* OBJC_SPARSE2 */
  73
  74 /* Buckets are 32 words each */
  75 #define BUCKET_BITS 5
  76 #define BUCKET_SIZE (1<<BUCKET_BITS)
  77 #define BUCKET_MASK (BUCKET_SIZE-1)
  78
  79 #endif /* OBJC_SPARSE2 */
  80
  81 typedef size_t sidx;
  82
  83 #ifdef PRECOMPUTE_SELECTORS
  84
  85 struct soffset {
  86 #ifdef OBJC_SPARSE3
  87   unsigned int unused : SIZET_BITS/4;
  88   unsigned int eoffset : SIZET_BITS/4;
  89   unsigned int boffset : SIZET_BITS/4;
  90   unsigned int ioffset : SIZET_BITS/4;
  91 #else /* OBJC_SPARSE2 */
  92 #ifdef __sparc__
  93   unsigned long boffset : (SIZET_BITS - 2) - BUCKET_BITS;
  94   unsigned int eoffset : BUCKET_BITS;
  95   unsigned int unused  : 2;
  96 #else
  97   unsigned int boffset : SIZET_BITS/2;
  98   unsigned int eoffset : SIZET_BITS/2;
  99 #endif
 100 #endif /* OBJC_SPARSE2 */
 101 };
 102
 103 union sofftype {
 104   struct soffset off;
 105   sidx idx;
 106 };
 107
 108 #endif /* not PRECOMPUTE_SELECTORS */
 109
 110 union sversion {
 111   int   version;
 112   void *next_free;
 113 };
 114
 115 struct sbucket {
 116   void* elems[BUCKET_SIZE];     /* elements stored in array */
 117   union sversion        version;                /* used for copy-on-write */
 118 };
 119
 120 #ifdef OBJC_SPARSE3
 121
 122 struct sindex {
 123   struct sbucket* buckets[INDEX_SIZE];
 124   union sversion        version;                /* used for copy-on-write */
 125 };
 126
 127 #endif /* OBJC_SPARSE3 */
 128
 129 struct sarray {
 130 #ifdef OBJC_SPARSE3
 131   struct sindex** indices;
 132   struct sindex* empty_index;
 133 #else /* OBJC_SPARSE2 */
 134   struct sbucket** buckets;
 135 #endif  /* OBJC_SPARSE2 */
 136   struct sbucket* empty_bucket;
 137   union sversion        version;                /* used for copy-on-write */
 138   short ref_count;
 139   struct sarray* is_copy_of;
 140   size_t capacity;
 141 };
 142
 143 struct sarray* sarray_new(int, void* default_element);
 144 void sarray_free(struct sarray*);
 145 struct sarray* sarray_lazy_copy(struct sarray*);
 146 void sarray_realloc(struct sarray*, int new_size);
 147 void sarray_at_put(struct sarray*, sidx indx, void* elem);
 148 void sarray_at_put_safe(struct sarray*, sidx indx, void* elem);
 149
 150 struct sarray* sarray_hard_copy(struct sarray*); /* ... like the name? */
 151 void sarray_remove_garbage(void);
 152 \f
 153
 154 #ifdef PRECOMPUTE_SELECTORS
 155 /* Transform soffset values to ints and vica verca */
 156 static inline unsigned int
 157 soffset_decode(sidx indx)
 158 {
 159   union sofftype x;
 160   x.idx = indx;
 161 #ifdef OBJC_SPARSE3
 162   return x.off.eoffset
 163     + (x.off.boffset*BUCKET_SIZE)
 164       + (x.off.ioffset*INDEX_CAPACITY);
 165 #else /* OBJC_SPARSE2 */
 166   return x.off.eoffset + (x.off.boffset*BUCKET_SIZE);
 167 #endif /* OBJC_SPARSE2 */
 168 }
 169
 170 static inline sidx
 171 soffset_encode(size_t offset)
 172 {
 173   union sofftype x;
 174   x.off.eoffset = offset%BUCKET_SIZE;
 175 #ifdef OBJC_SPARSE3
 176   x.off.boffset = (offset/BUCKET_SIZE)%INDEX_SIZE;
 177   x.off.ioffset = offset/INDEX_CAPACITY;
 178 #else /* OBJC_SPARSE2 */
 179   x.off.boffset = offset/BUCKET_SIZE;
 180 #endif
 181   return (sidx)x.idx;
 182 }
 183
 184 #else /* not PRECOMPUTE_SELECTORS */
 185
 186 static inline size_t
 187 soffset_decode(sidx indx)
 188 {
 189   return indx;
 190 }
 191
 192 static inline sidx
 193 soffset_encode(size_t offset)
 194 {
 195   return offset;
 196 }
 197 #endif /* not PRECOMPUTE_SELECTORS */
 198
 199 /* Get element from the Sparse array `array' at offset `indx' */
 200
 201 static inline void* sarray_get(struct sarray* array, sidx indx)
 202 {
 203 #ifdef PRECOMPUTE_SELECTORS
 204   union sofftype x;
 205   x.idx = indx;
 206 #ifdef OBJC_SPARSE3
 207   return
 208     array->
 209       indices[x.off.ioffset]->
 210         buckets[x.off.boffset]->
 211           elems[x.off.eoffset];
 212 #else /* OBJC_SPARSE2 */
 213   return array->buckets[x.off.boffset]->elems[x.off.eoffset];
 214 #endif /* OBJC_SPARSE2 */
 215 #else /* not PRECOMPUTE_SELECTORS */
 216 #ifdef OBJC_SPARSE3
 217   return array->
 218     indices[indx/INDEX_CAPACITY]->
 219       buckets[(indx/BUCKET_SIZE)%INDEX_SIZE]->
 220         elems[indx%BUCKET_SIZE];
 221 #else /* OBJC_SPARSE2 */
 222   return array->buckets[indx/BUCKET_SIZE]->elems[indx%BUCKET_SIZE];
 223 #endif /* not OBJC_SPARSE3 */
 224 #endif /* not PRECOMPUTE_SELECTORS */
 225 }
 226
 227 static inline void* sarray_get_safe(struct sarray* array, sidx indx)
 228 {
 229   if(soffset_decode(indx) < array->capacity)
 230     return sarray_get(array, indx);
 231   else
 232     return (array->empty_bucket->elems[0]);
 233 }
 234
 235 #ifdef __cplusplus
 236 }
 237 #endif /* __cplusplus */
 238
 239 #endif /* __sarray_INCLUDE_GNU */