libobjc/objc-private/sarray.h

   1 /* Sparse Arrays for Objective C dispatch tables
   2    Copyright (C) 1993-2024 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 extern int nbuckets;            /* for stats */
  43 extern int nindices;
  44 extern int narrays;
  45 extern int idxsize;
  46
  47 /* An unsigned integer of same size as a pointer.  */
  48 #define SIZET_BITS (sizeof (size_t) * 8)
  49
  50 #if defined (__sparc__) || defined (OBJC_SPARSE2)
  51 #define PRECOMPUTE_SELECTORS
  52 #endif
  53
  54 #ifdef OBJC_SPARSE3
  55
  56 /* Buckets are 8 words each.  */
  57 #define BUCKET_BITS 3
  58 #define BUCKET_SIZE (1 << BUCKET_BITS)
  59 #define BUCKET_MASK (BUCKET_SIZE - 1)
  60
  61 /* Indices are 16 words each.  */
  62 #define INDEX_BITS 4
  63 #define INDEX_SIZE (1 << INDEX_BITS)
  64 #define INDEX_MASK (INDEX_SIZE - 1)
  65
  66 #define INDEX_CAPACITY (BUCKET_SIZE * INDEX_SIZE)
  67
  68 #else /* OBJC_SPARSE2 */
  69
  70 /* Buckets are 32 words each.  */
  71 #define BUCKET_BITS 5
  72 #define BUCKET_SIZE (1 << BUCKET_BITS)
  73 #define BUCKET_MASK (BUCKET_SIZE - 1)
  74
  75 #endif /* OBJC_SPARSE2 */
  76
  77 typedef size_t sidx;
  78
  79 #ifdef PRECOMPUTE_SELECTORS
  80
  81 struct soffset
  82 {
  83 #ifdef OBJC_SPARSE3
  84   unsigned int unused : SIZET_BITS / 4;
  85   unsigned int eoffset : SIZET_BITS / 4;
  86   unsigned int boffset : SIZET_BITS / 4;
  87   unsigned int ioffset : SIZET_BITS / 4;
  88 #else /* OBJC_SPARSE2 */
  89 #ifdef __sparc__
  90   unsigned long boffset : (SIZET_BITS - 2) - BUCKET_BITS;
  91   unsigned int eoffset : BUCKET_BITS;
  92   unsigned int unused  : 2;
  93 #else
  94   unsigned int boffset : SIZET_BITS / 2;
  95   unsigned int eoffset : SIZET_BITS / 2;
  96 #endif
  97 #endif /* OBJC_SPARSE2 */
  98 };
  99
 100 union sofftype
 101 {
 102   struct soffset off;
 103   sidx idx;
 104 };
 105
 106 #endif /* not PRECOMPUTE_SELECTORS */
 107
 108 union sversion
 109 {
 110   int   version;
 111   void *next_free;
 112 };
 113
 114 struct sbucket
 115 {
 116   /* Elements stored in array.  */
 117   void* elems[BUCKET_SIZE];
 118
 119   /* Used for copy-on-write.  */
 120   union sversion version;
 121 };
 122
 123 #ifdef OBJC_SPARSE3
 124
 125 struct sindex
 126 {
 127   struct sbucket* buckets[INDEX_SIZE];
 128
 129   /* Used for copy-on-write. */
 130   union sversion version;
 131 };
 132
 133 #endif /* OBJC_SPARSE3 */
 134
 135 struct sarray
 136 {
 137 #ifdef OBJC_SPARSE3
 138   struct sindex** indices;
 139   struct sindex* empty_index;
 140 #else /* OBJC_SPARSE2 */
 141   struct sbucket** buckets;
 142 #endif  /* OBJC_SPARSE2 */
 143   struct sbucket* empty_bucket;
 144
 145   /* Used for copy-on-write. */
 146   union sversion version;
 147
 148   short ref_count;
 149   struct sarray* is_copy_of;
 150   size_t capacity;
 151 };
 152
 153 struct sarray* sarray_new (int, void* default_element);
 154 void sarray_free (struct sarray*);
 155 struct sarray* sarray_lazy_copy (struct sarray*);
 156 void sarray_realloc (struct sarray*, int new_size);
 157 void sarray_at_put (struct sarray*, sidx indx, void* elem);
 158 void sarray_at_put_safe (struct sarray*, sidx indx, void* elem);
 159
 160 struct sarray* sarray_hard_copy (struct sarray*); /* ... like the name ?  */
 161 void sarray_remove_garbage (void);
 162 \f
 163
 164 #ifdef PRECOMPUTE_SELECTORS
 165 /* Transform soffset values to ints and vice versa.  */
 166 static inline unsigned int
 167 soffset_decode (sidx indx)
 168 {
 169   union sofftype x;
 170   x.idx = indx;
 171 #ifdef OBJC_SPARSE3
 172   return x.off.eoffset
 173     + (x.off.boffset * BUCKET_SIZE)
 174     + (x.off.ioffset * INDEX_CAPACITY);
 175 #else /* OBJC_SPARSE2 */
 176   return x.off.eoffset + (x.off.boffset * BUCKET_SIZE);
 177 #endif /* OBJC_SPARSE2 */
 178 }
 179
 180 static inline sidx
 181 soffset_encode (size_t offset)
 182 {
 183   union sofftype x;
 184   x.off.eoffset = offset % BUCKET_SIZE;
 185 #ifdef OBJC_SPARSE3
 186   x.off.boffset = (offset / BUCKET_SIZE) % INDEX_SIZE;
 187   x.off.ioffset = offset / INDEX_CAPACITY;
 188 #else /* OBJC_SPARSE2 */
 189   x.off.boffset = offset / BUCKET_SIZE;
 190 #endif
 191   return (sidx)x.idx;
 192 }
 193
 194 #else /* not PRECOMPUTE_SELECTORS */
 195
 196 static inline size_t
 197 soffset_decode (sidx indx)
 198 {
 199   return indx;
 200 }
 201
 202 static inline sidx
 203 soffset_encode (size_t offset)
 204 {
 205   return offset;
 206 }
 207 #endif /* not PRECOMPUTE_SELECTORS */
 208
 209 /* Get element from the Sparse array `array' at offset `indx'.  */
 210 static inline void* sarray_get (struct sarray* array, sidx indx)
 211 {
 212 #ifdef PRECOMPUTE_SELECTORS
 213   union sofftype x;
 214   x.idx = indx;
 215 #ifdef OBJC_SPARSE3
 216   return array->
 217     indices[x.off.ioffset]->
 218     buckets[x.off.boffset]->
 219     elems[x.off.eoffset];
 220 #else /* OBJC_SPARSE2 */
 221   return array->buckets[x.off.boffset]->elems[x.off.eoffset];
 222 #endif /* OBJC_SPARSE2 */
 223 #else /* not PRECOMPUTE_SELECTORS */
 224 #ifdef OBJC_SPARSE3
 225   return array->
 226     indices[indx / INDEX_CAPACITY]->
 227     buckets[(indx / BUCKET_SIZE) % INDEX_SIZE]->
 228     elems[indx % BUCKET_SIZE];
 229 #else /* OBJC_SPARSE2 */
 230   return array->buckets[indx / BUCKET_SIZE]->elems[indx % BUCKET_SIZE];
 231 #endif /* not OBJC_SPARSE3 */
 232 #endif /* not PRECOMPUTE_SELECTORS */
 233 }
 234
 235 static inline void* sarray_get_safe (struct sarray* array, sidx indx)
 236 {
 237   if (soffset_decode (indx) < array->capacity)
 238     return sarray_get (array, indx);
 239   else
 240     return (array->empty_bucket->elems[0]);
 241 }
 242
 243 #endif /* __sarray_INCLUDE_GNU */