gcc/sbitmap.h

   1 /* Simple bitmaps.
   2    Copyright (C) 1999-2023 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef GCC_SBITMAP_H
  21 #define GCC_SBITMAP_H
  22
  23 /* Implementation of sets using simple bitmap vectors.
  24
  25    This set representation is suitable for non-sparse sets with a known
  26    (a priori) universe.  The set is represented as a simple array of the
  27    host's fastest unsigned integer.  For a given member I in the set:
  28      - the element for I will be at sbitmap[I / (bits per element)]
  29      - the position for I within element is I % (bits per element)
  30
  31    This representation is very space-efficient for large non-sparse sets
  32    with random access patterns.
  33
  34    The following operations can be performed in O(1) time:
  35
  36      * set_size                 : SBITMAP_SIZE
  37      * member_p                 : bitmap_bit_p
  38      * add_member               : bitmap_set_bit
  39      * remove_member            : bitmap_clear_bit
  40
  41    Most other operations on this set representation are O(U) where U is
  42    the size of the set universe:
  43
  44      * clear                    : bitmap_clear
  45      * choose_one               : bitmap_first_set_bit /
  46                                   bitmap_last_set_bit
  47      * forall                   : EXECUTE_IF_SET_IN_BITMAP
  48      * set_copy                 : bitmap_copy
  49      * set_intersection         : bitmap_and
  50      * set_union                : bitmap_ior
  51      * set_difference           : bitmap_and_compl
  52      * set_disjuction           : (not implemented)
  53      * set_compare              : bitmap_equal_p
  54      * bit_in_range_p           : bitmap_bit_in_range_p
  55
  56    Some operations on 3 sets that occur frequently in data flow problems
  57    are also implemented:
  58
  59       * A | (B & C)             : bitmap_or_and
  60       * A | (B & ~C)            : bitmap_ior_and_compl
  61       * A & (B | C)             : bitmap_and_or
  62
  63    Most of the set functions have two variants: One that returns non-zero
  64    if members were added or removed from the target set, and one that just
  65    performs the operation without feedback.  The former operations are a
  66    bit more expensive but the result can often be used to avoid iterations
  67    on other sets.
  68
  69    Allocating a bitmap is done with sbitmap_alloc, and resizing is
  70    performed with sbitmap_resize.
  71
  72    The storage requirements for simple bitmap sets is O(U) where U is the
  73    size of the set universe (colloquially the number of bits in the bitmap).
  74
  75    This set representation works well for relatively small data flow problems
  76    (there are special routines for that, see sbitmap_vector_*).  The set
  77    operations can be vectorized and there is almost no computating overhead,
  78    so that even sparse simple bitmap sets outperform dedicated sparse set
  79    representations like linked-list bitmaps.  For larger problems, the size
  80    overhead of simple bitmap sets gets too high and other set representations
  81    have to be used.  */
  82
  83 #define SBITMAP_ELT_BITS (HOST_BITS_PER_WIDEST_FAST_INT * 1u)
  84 #define SBITMAP_ELT_TYPE unsigned HOST_WIDEST_FAST_INT
  85
  86 struct simple_bitmap_def
  87 {
  88   unsigned int n_bits;          /* Number of bits.  */
  89   unsigned int size;            /* Size in elements.  */
  90   SBITMAP_ELT_TYPE elms[1];     /* The elements.  */
  91 };
  92
  93 /* Return the set size needed for N elements.  */
  94 #define SBITMAP_SET_SIZE(N) (((N) + SBITMAP_ELT_BITS - 1) / SBITMAP_ELT_BITS)
  95
  96 /* Return the number of bits in BITMAP.  */
  97 #define SBITMAP_SIZE(BITMAP) ((BITMAP)->n_bits)
  98
  99 /* Verify that access at INDEX in bitmap MAP is valid.  */
 100
 101 inline void
 102 bitmap_check_index (const_sbitmap map, int index)
 103 {
 104   gcc_checking_assert (index >= 0);
 105   gcc_checking_assert ((unsigned int)index < map->n_bits);
 106 }
 107
 108 /* Verify that bitmaps A and B have same size.  */
 109
 110 inline void
 111 bitmap_check_sizes (const_sbitmap a, const_sbitmap b)
 112 {
 113   gcc_checking_assert (a->n_bits == b->n_bits);
 114 }
 115
 116 /* Test if bit number bitno in the bitmap is set.  */
 117 inline bool
 118 bitmap_bit_p (const_sbitmap map, int bitno)
 119 {
 120   bitmap_check_index (map, bitno);
 121
 122   size_t i = bitno / SBITMAP_ELT_BITS;
 123   unsigned int s = bitno % SBITMAP_ELT_BITS;
 124   return (map->elms[i] >> s) & (SBITMAP_ELT_TYPE) 1;
 125 }
 126
 127 /* Set bit number BITNO in the sbitmap MAP.
 128    Return true if the bit changed.  */
 129
 130 inline bool
 131 bitmap_set_bit (sbitmap map, int bitno)
 132 {
 133   bitmap_check_index (map, bitno);
 134
 135   size_t i = bitno / SBITMAP_ELT_BITS;
 136   unsigned int s = bitno % SBITMAP_ELT_BITS;
 137   if (map->elms[i] & ((SBITMAP_ELT_TYPE) 1 << s))
 138     return false;
 139   map->elms[i] |= (SBITMAP_ELT_TYPE) 1 << s;
 140   return true;
 141 }
 142
 143 /* Reset bit number BITNO in the sbitmap MAP.
 144    Return true if the bit changed.  */
 145
 146 inline bool
 147 bitmap_clear_bit (sbitmap map, int bitno)
 148 {
 149   bitmap_check_index (map, bitno);
 150
 151   size_t i = bitno / SBITMAP_ELT_BITS;
 152   unsigned int s = bitno % SBITMAP_ELT_BITS;
 153   if (!(map->elms[i] & ((SBITMAP_ELT_TYPE) 1 << s)))
 154     return false;
 155   map->elms[i] &= ~((SBITMAP_ELT_TYPE) 1 << s);
 156   return true;
 157 }
 158
 159 /* The iterator for sbitmap.  */
 160 struct sbitmap_iterator {
 161   /* The pointer to the first word of the bitmap.  */
 162   const SBITMAP_ELT_TYPE *ptr;
 163
 164   /* The size of the bitmap.  */
 165   unsigned int size;
 166
 167   /* The current word index.  */
 168   unsigned int word_num;
 169
 170   /* The current bit index (not modulo SBITMAP_ELT_BITS).  */
 171   unsigned int bit_num;
 172
 173   /* The words currently visited.  */
 174   SBITMAP_ELT_TYPE word;
 175 };
 176
 177 /* Initialize the iterator I with sbitmap BMP and the initial index
 178    MIN.  */
 179
 180 inline void
 181 bmp_iter_set_init (sbitmap_iterator *i, const_sbitmap bmp,
 182                    unsigned int min, unsigned *bit_no ATTRIBUTE_UNUSED)
 183 {
 184   i->word_num = min / (unsigned int) SBITMAP_ELT_BITS;
 185   i->bit_num = min;
 186   i->size = bmp->size;
 187   i->ptr = bmp->elms;
 188
 189   if (i->word_num >= i->size)
 190     i->word = 0;
 191   else
 192     i->word = (i->ptr[i->word_num]
 193                >> (i->bit_num % (unsigned int) SBITMAP_ELT_BITS));
 194 }
 195
 196 /* Return true if we have more bits to visit, in which case *N is set
 197    to the index of the bit to be visited.  Otherwise, return
 198    false.  */
 199
 200 inline bool
 201 bmp_iter_set (sbitmap_iterator *i, unsigned int *n)
 202 {
 203   /* Skip words that are zeros.  */
 204   for (; i->word == 0; i->word = i->ptr[i->word_num])
 205     {
 206       i->word_num++;
 207
 208       /* If we have reached the end, break.  */
 209       if (i->word_num >= i->size)
 210         return false;
 211
 212       i->bit_num = i->word_num * SBITMAP_ELT_BITS;
 213     }
 214
 215   /* Skip bits that are zero.  */
 216   for (; (i->word & 1) == 0; i->word >>= 1)
 217     i->bit_num++;
 218
 219   *n = i->bit_num;
 220
 221   return true;
 222 }
 223
 224 /* Advance to the next bit.  */
 225
 226 inline void
 227 bmp_iter_next (sbitmap_iterator *i, unsigned *bit_no ATTRIBUTE_UNUSED)
 228 {
 229   i->word >>= 1;
 230   i->bit_num++;
 231 }
 232
 233 /* Loop over all elements of SBITMAP, starting with MIN.  In each
 234    iteration, N is set to the index of the bit being visited.  ITER is
 235    an instance of sbitmap_iterator used to iterate the bitmap.  */
 236
 237 #ifndef EXECUTE_IF_SET_IN_BITMAP
 238 /* See bitmap.h for the other definition of EXECUTE_IF_SET_IN_BITMAP.  */
 239 #define EXECUTE_IF_SET_IN_BITMAP(BITMAP, MIN, BITNUM, ITER)     \
 240   for (bmp_iter_set_init (&(ITER), (BITMAP), (MIN), &(BITNUM)); \
 241        bmp_iter_set (&(ITER), &(BITNUM));                       \
 242        bmp_iter_next (&(ITER), &(BITNUM)))
 243 #endif
 244
 245 inline void sbitmap_free (sbitmap map)
 246 {
 247   free (map);
 248 }
 249
 250 inline void sbitmap_vector_free (sbitmap * vec)
 251 {
 252   free (vec);
 253 }
 254
 255 extern void dump_bitmap (FILE *, const_sbitmap);
 256 extern void debug_raw (const simple_bitmap_def &ref);
 257 extern void debug_raw (const simple_bitmap_def *ptr);
 258 extern void dump_bitmap_file (FILE *, const_sbitmap);
 259 extern void debug (const simple_bitmap_def &ref);
 260 extern void debug (const simple_bitmap_def *ptr);
 261 extern void dump_bitmap_vector (FILE *, const char *, const char *, sbitmap *,
 262                                  int);
 263 extern sbitmap sbitmap_alloc (unsigned int);
 264 extern sbitmap *sbitmap_vector_alloc (unsigned int, unsigned int);
 265 extern sbitmap sbitmap_resize (sbitmap, unsigned int, int);
 266 extern void bitmap_copy (sbitmap, const_sbitmap);
 267 extern int bitmap_equal_p (const_sbitmap, const_sbitmap);
 268 extern unsigned int bitmap_count_bits (const_sbitmap);
 269 extern bool bitmap_empty_p (const_sbitmap);
 270 extern void bitmap_clear (sbitmap);
 271 extern void bitmap_clear_range (sbitmap, unsigned, unsigned);
 272 extern void bitmap_set_range (sbitmap, unsigned, unsigned);
 273 extern void bitmap_ones (sbitmap);
 274 extern void bitmap_vector_clear (sbitmap *, unsigned int);
 275 extern void bitmap_vector_ones (sbitmap *, unsigned int);
 276
 277 extern bool bitmap_ior_and_compl (sbitmap, const_sbitmap,
 278                                       const_sbitmap, const_sbitmap);
 279 extern void bitmap_and_compl (sbitmap, const_sbitmap, const_sbitmap);
 280 extern void bitmap_not (sbitmap, const_sbitmap);
 281 extern bool bitmap_or_and (sbitmap, const_sbitmap,
 282                                      const_sbitmap, const_sbitmap);
 283 extern bool bitmap_and_or (sbitmap, const_sbitmap,
 284                                      const_sbitmap, const_sbitmap);
 285 extern bool bitmap_intersect_p (const_sbitmap, const_sbitmap);
 286 extern bool bitmap_and (sbitmap, const_sbitmap, const_sbitmap);
 287 extern bool bitmap_ior (sbitmap, const_sbitmap, const_sbitmap);
 288 extern bool bitmap_xor (sbitmap, const_sbitmap, const_sbitmap);
 289 extern bool bitmap_subset_p (const_sbitmap, const_sbitmap);
 290 extern bool bitmap_bit_in_range_p (const_sbitmap, unsigned int, unsigned int);
 291
 292 extern int bitmap_first_set_bit (const_sbitmap);
 293 extern int bitmap_last_set_bit (const_sbitmap);
 294
 295 extern void debug_bitmap (const_sbitmap);
 296 extern sbitmap sbitmap_realloc (sbitmap, unsigned int);
 297
 298 /* a class that ties the lifetime of a sbitmap to its scope.  */
 299 class auto_sbitmap
 300 {
 301 public:
 302   explicit auto_sbitmap (unsigned int size) :
 303     m_bitmap (sbitmap_alloc (size)) {}
 304   ~auto_sbitmap () { sbitmap_free (m_bitmap); }
 305
 306   /* Allow calling sbitmap functions on our bitmap.  */
 307   operator sbitmap () { return m_bitmap; }
 308   operator const_sbitmap () const { return m_bitmap; }
 309
 310 private:
 311   /* Prevent making a copy that refers to our sbitmap.  */
 312   auto_sbitmap (const auto_sbitmap &);
 313   auto_sbitmap &operator = (const auto_sbitmap &);
 314   auto_sbitmap (auto_sbitmap &&);
 315   auto_sbitmap &operator = (auto_sbitmap &&);
 316
 317   /* The bitmap we are managing.  */
 318   sbitmap m_bitmap;
 319 };
 320
 321 #endif /* ! GCC_SBITMAP_H */