gcc/sbitmap.h

   1 /* Simple bitmaps.
   2    Copyright (C) 1999-2020 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 static 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 static 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 static inline SBITMAP_ELT_TYPE
 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
 129 static inline void
 130 bitmap_set_bit (sbitmap map, int bitno)
 131 {
 132   bitmap_check_index (map, bitno);
 133
 134   map->elms[bitno / SBITMAP_ELT_BITS]
 135     |= (SBITMAP_ELT_TYPE) 1 << (bitno) % SBITMAP_ELT_BITS;
 136 }
 137
 138 /* Reset bit number BITNO in the sbitmap MAP.  */
 139
 140 static inline void
 141 bitmap_clear_bit (sbitmap map, int bitno)
 142 {
 143   bitmap_check_index (map, bitno);
 144
 145   map->elms[bitno / SBITMAP_ELT_BITS]
 146     &= ~((SBITMAP_ELT_TYPE) 1 << (bitno) % SBITMAP_ELT_BITS);
 147 }
 148
 149 /* The iterator for sbitmap.  */
 150 struct sbitmap_iterator {
 151   /* The pointer to the first word of the bitmap.  */
 152   const SBITMAP_ELT_TYPE *ptr;
 153
 154   /* The size of the bitmap.  */
 155   unsigned int size;
 156
 157   /* The current word index.  */
 158   unsigned int word_num;
 159
 160   /* The current bit index (not modulo SBITMAP_ELT_BITS).  */
 161   unsigned int bit_num;
 162
 163   /* The words currently visited.  */
 164   SBITMAP_ELT_TYPE word;
 165 };
 166
 167 /* Initialize the iterator I with sbitmap BMP and the initial index
 168    MIN.  */
 169
 170 static inline void
 171 bmp_iter_set_init (sbitmap_iterator *i, const_sbitmap bmp,
 172                    unsigned int min, unsigned *bit_no ATTRIBUTE_UNUSED)
 173 {
 174   i->word_num = min / (unsigned int) SBITMAP_ELT_BITS;
 175   i->bit_num = min;
 176   i->size = bmp->size;
 177   i->ptr = bmp->elms;
 178
 179   if (i->word_num >= i->size)
 180     i->word = 0;
 181   else
 182     i->word = (i->ptr[i->word_num]
 183                >> (i->bit_num % (unsigned int) SBITMAP_ELT_BITS));
 184 }
 185
 186 /* Return true if we have more bits to visit, in which case *N is set
 187    to the index of the bit to be visited.  Otherwise, return
 188    false.  */
 189
 190 static inline bool
 191 bmp_iter_set (sbitmap_iterator *i, unsigned int *n)
 192 {
 193   /* Skip words that are zeros.  */
 194   for (; i->word == 0; i->word = i->ptr[i->word_num])
 195     {
 196       i->word_num++;
 197
 198       /* If we have reached the end, break.  */
 199       if (i->word_num >= i->size)
 200         return false;
 201
 202       i->bit_num = i->word_num * SBITMAP_ELT_BITS;
 203     }
 204
 205   /* Skip bits that are zero.  */
 206   for (; (i->word & 1) == 0; i->word >>= 1)
 207     i->bit_num++;
 208
 209   *n = i->bit_num;
 210
 211   return true;
 212 }
 213
 214 /* Advance to the next bit.  */
 215
 216 static inline void
 217 bmp_iter_next (sbitmap_iterator *i, unsigned *bit_no ATTRIBUTE_UNUSED)
 218 {
 219   i->word >>= 1;
 220   i->bit_num++;
 221 }
 222
 223 /* Loop over all elements of SBITMAP, starting with MIN.  In each
 224    iteration, N is set to the index of the bit being visited.  ITER is
 225    an instance of sbitmap_iterator used to iterate the bitmap.  */
 226
 227 #ifndef EXECUTE_IF_SET_IN_BITMAP
 228 /* See bitmap.h for the other definition of EXECUTE_IF_SET_IN_BITMAP.  */
 229 #define EXECUTE_IF_SET_IN_BITMAP(BITMAP, MIN, BITNUM, ITER)     \
 230   for (bmp_iter_set_init (&(ITER), (BITMAP), (MIN), &(BITNUM)); \
 231        bmp_iter_set (&(ITER), &(BITNUM));                       \
 232        bmp_iter_next (&(ITER), &(BITNUM)))
 233 #endif
 234
 235 inline void sbitmap_free (sbitmap map)
 236 {
 237   free (map);
 238 }
 239
 240 inline void sbitmap_vector_free (sbitmap * vec)
 241 {
 242   free (vec);
 243 }
 244
 245 extern void dump_bitmap (FILE *, const_sbitmap);
 246 extern void debug_raw (const simple_bitmap_def &ref);
 247 extern void debug_raw (const simple_bitmap_def *ptr);
 248 extern void dump_bitmap_file (FILE *, const_sbitmap);
 249 extern void debug (const simple_bitmap_def &ref);
 250 extern void debug (const simple_bitmap_def *ptr);
 251 extern void dump_bitmap_vector (FILE *, const char *, const char *, sbitmap *,
 252                                  int);
 253 extern sbitmap sbitmap_alloc (unsigned int);
 254 extern sbitmap *sbitmap_vector_alloc (unsigned int, unsigned int);
 255 extern sbitmap sbitmap_resize (sbitmap, unsigned int, int);
 256 extern void bitmap_copy (sbitmap, const_sbitmap);
 257 extern int bitmap_equal_p (const_sbitmap, const_sbitmap);
 258 extern unsigned int bitmap_count_bits (const_sbitmap);
 259 extern bool bitmap_empty_p (const_sbitmap);
 260 extern void bitmap_clear (sbitmap);
 261 extern void bitmap_clear_range (sbitmap, unsigned, unsigned);
 262 extern void bitmap_set_range (sbitmap, unsigned, unsigned);
 263 extern void bitmap_ones (sbitmap);
 264 extern void bitmap_vector_clear (sbitmap *, unsigned int);
 265 extern void bitmap_vector_ones (sbitmap *, unsigned int);
 266
 267 extern bool bitmap_ior_and_compl (sbitmap, const_sbitmap,
 268                                       const_sbitmap, const_sbitmap);
 269 extern void bitmap_and_compl (sbitmap, const_sbitmap, const_sbitmap);
 270 extern void bitmap_not (sbitmap, const_sbitmap);
 271 extern bool bitmap_or_and (sbitmap, const_sbitmap,
 272                                      const_sbitmap, const_sbitmap);
 273 extern bool bitmap_and_or (sbitmap, const_sbitmap,
 274                                      const_sbitmap, const_sbitmap);
 275 extern bool bitmap_intersect_p (const_sbitmap, const_sbitmap);
 276 extern bool bitmap_and (sbitmap, const_sbitmap, const_sbitmap);
 277 extern bool bitmap_ior (sbitmap, const_sbitmap, const_sbitmap);
 278 extern bool bitmap_xor (sbitmap, const_sbitmap, const_sbitmap);
 279 extern bool bitmap_subset_p (const_sbitmap, const_sbitmap);
 280 extern bool bitmap_bit_in_range_p (const_sbitmap, unsigned int, unsigned int);
 281
 282 extern int bitmap_first_set_bit (const_sbitmap);
 283 extern int bitmap_last_set_bit (const_sbitmap);
 284
 285 extern void debug_bitmap (const_sbitmap);
 286 extern sbitmap sbitmap_realloc (sbitmap, unsigned int);
 287
 288 /* a class that ties the lifetime of a sbitmap to its scope.  */
 289 class auto_sbitmap
 290 {
 291 public:
 292   explicit auto_sbitmap (unsigned int size) :
 293     m_bitmap (sbitmap_alloc (size)) {}
 294   ~auto_sbitmap () { sbitmap_free (m_bitmap); }
 295
 296   /* Allow calling sbitmap functions on our bitmap.  */
 297   operator sbitmap () { return m_bitmap; }
 298   operator const_sbitmap () const { return m_bitmap; }
 299
 300 private:
 301   /* Prevent making a copy that refers to our sbitmap.  */
 302   auto_sbitmap (const auto_sbitmap &);
 303   auto_sbitmap &operator = (const auto_sbitmap &);
 304 #if __cplusplus >= 201103L
 305   auto_sbitmap (auto_sbitmap &&);
 306   auto_sbitmap &operator = (auto_sbitmap &&);
 307 #endif
 308
 309   /* The bitmap we are managing.  */
 310   sbitmap m_bitmap;
 311 };
 312
 313 #endif /* ! GCC_SBITMAP_H */