gcc/sbitmap.h

   1 /* Simple bitmaps.
   2    Copyright (C) 1999-2013 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
  55    Some operations on 3 sets that occur frequently in in data flow problems
  56    are also implemented:
  57
  58       * A | (B & C)             : bitmap_or_and
  59       * A | (B & ~C)            : bitmap_ior_and_compl
  60       * A & (B | C)             : bitmap_and_or
  61
  62    Most of the set functions have two variants: One that returns non-zero
  63    if members were added or removed from the target set, and one that just
  64    performs the operation without feedback.  The former operations are a
  65    bit more expensive but the result can often be used to avoid iterations
  66    on other sets.
  67
  68    Allocating a bitmap is done with sbitmap_alloc, and resizing is
  69    performed with sbitmap_resize.
  70
  71    The storage requirements for simple bitmap sets is O(U) where U is the
  72    size of the set universe (colloquially the number of bits in the bitmap).
  73
  74    This set representation works well for relatively small data flow problems
  75    (there are special routines for that, see sbitmap_vector_*).  The set
  76    operations can be vectorized and there is almost no computating overhead,
  77    so that even sparse simple bitmap sets outperform dedicated sparse set
  78    representations like linked-list bitmaps.  For larger problems, the size
  79    overhead of simple bitmap sets gets too high and other set representations
  80    have to be used.  */
  81
  82 #define SBITMAP_ELT_BITS (HOST_BITS_PER_WIDEST_FAST_INT * 1u)
  83 #define SBITMAP_ELT_TYPE unsigned HOST_WIDEST_FAST_INT
  84
  85 struct simple_bitmap_def
  86 {
  87   unsigned char *popcount;      /* Population count.  */
  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 /* Test if bit number bitno in the bitmap is set.  */
 100 static inline SBITMAP_ELT_TYPE
 101 bitmap_bit_p (const_sbitmap map, int bitno)
 102 {
 103   size_t i = bitno / SBITMAP_ELT_BITS;
 104   unsigned int s = bitno % SBITMAP_ELT_BITS;
 105   return (map->elms[i] >> s) & (SBITMAP_ELT_TYPE) 1;
 106 }
 107
 108 /* Set bit number BITNO in the sbitmap MAP.  */
 109
 110 static inline void
 111 bitmap_set_bit (sbitmap map, int bitno)
 112 {
 113   gcc_checking_assert (! map->popcount);
 114   map->elms[bitno / SBITMAP_ELT_BITS]
 115     |= (SBITMAP_ELT_TYPE) 1 << (bitno) % SBITMAP_ELT_BITS;
 116 }
 117
 118 /* Reset bit number BITNO in the sbitmap MAP.  */
 119
 120 static inline void
 121 bitmap_clear_bit (sbitmap map, int bitno)
 122 {
 123   gcc_checking_assert (! map->popcount);
 124   map->elms[bitno / SBITMAP_ELT_BITS]
 125     &= ~((SBITMAP_ELT_TYPE) 1 << (bitno) % SBITMAP_ELT_BITS);
 126 }
 127
 128 /* The iterator for sbitmap.  */
 129 typedef struct {
 130   /* The pointer to the first word of the bitmap.  */
 131   const SBITMAP_ELT_TYPE *ptr;
 132
 133   /* The size of the bitmap.  */
 134   unsigned int size;
 135
 136   /* The current word index.  */
 137   unsigned int word_num;
 138
 139   /* The current bit index (not modulo SBITMAP_ELT_BITS).  */
 140   unsigned int bit_num;
 141
 142   /* The words currently visited.  */
 143   SBITMAP_ELT_TYPE word;
 144 } sbitmap_iterator;
 145
 146 /* Initialize the iterator I with sbitmap BMP and the initial index
 147    MIN.  */
 148
 149 static inline void
 150 bmp_iter_set_init (sbitmap_iterator *i, const_sbitmap bmp,
 151                    unsigned int min, unsigned *bit_no ATTRIBUTE_UNUSED)
 152 {
 153   i->word_num = min / (unsigned int) SBITMAP_ELT_BITS;
 154   i->bit_num = min;
 155   i->size = bmp->size;
 156   i->ptr = bmp->elms;
 157
 158   if (i->word_num >= i->size)
 159     i->word = 0;
 160   else
 161     i->word = (i->ptr[i->word_num]
 162                >> (i->bit_num % (unsigned int) SBITMAP_ELT_BITS));
 163 }
 164
 165 /* Return true if we have more bits to visit, in which case *N is set
 166    to the index of the bit to be visited.  Otherwise, return
 167    false.  */
 168
 169 static inline bool
 170 bmp_iter_set (sbitmap_iterator *i, unsigned int *n)
 171 {
 172   /* Skip words that are zeros.  */
 173   for (; i->word == 0; i->word = i->ptr[i->word_num])
 174     {
 175       i->word_num++;
 176
 177       /* If we have reached the end, break.  */
 178       if (i->word_num >= i->size)
 179         return false;
 180
 181       i->bit_num = i->word_num * SBITMAP_ELT_BITS;
 182     }
 183
 184   /* Skip bits that are zero.  */
 185   for (; (i->word & 1) == 0; i->word >>= 1)
 186     i->bit_num++;
 187
 188   *n = i->bit_num;
 189
 190   return true;
 191 }
 192
 193 /* Advance to the next bit.  */
 194
 195 static inline void
 196 bmp_iter_next (sbitmap_iterator *i, unsigned *bit_no ATTRIBUTE_UNUSED)
 197 {
 198   i->word >>= 1;
 199   i->bit_num++;
 200 }
 201
 202 /* Loop over all elements of SBITMAP, starting with MIN.  In each
 203    iteration, N is set to the index of the bit being visited.  ITER is
 204    an instance of sbitmap_iterator used to iterate the bitmap.  */
 205
 206 #ifndef EXECUTE_IF_SET_IN_BITMAP
 207 /* See bitmap.h for the other definition of EXECUTE_IF_SET_IN_BITMAP.  */
 208 #define EXECUTE_IF_SET_IN_BITMAP(BITMAP, MIN, BITNUM, ITER)     \
 209   for (bmp_iter_set_init (&(ITER), (BITMAP), (MIN), &(BITNUM)); \
 210        bmp_iter_set (&(ITER), &(BITNUM));                       \
 211        bmp_iter_next (&(ITER), &(BITNUM)))
 212 #endif
 213
 214 inline void sbitmap_free (sbitmap map)
 215 {
 216   free (map->popcount);
 217   free (map);
 218 }
 219
 220 inline void sbitmap_vector_free (sbitmap * vec)
 221 {
 222   free (vec);
 223 }
 224
 225 extern void dump_bitmap (FILE *, const_sbitmap);
 226 extern void dump_bitmap_file (FILE *, const_sbitmap);
 227 extern void dump_bitmap_vector (FILE *, const char *, const char *, sbitmap *,
 228                                  int);
 229 extern sbitmap sbitmap_alloc (unsigned int);
 230 extern sbitmap sbitmap_alloc_with_popcount (unsigned int);
 231 extern sbitmap *sbitmap_vector_alloc (unsigned int, unsigned int);
 232 extern sbitmap sbitmap_resize (sbitmap, unsigned int, int);
 233 extern void bitmap_copy (sbitmap, const_sbitmap);
 234 extern int bitmap_equal_p (const_sbitmap, const_sbitmap);
 235 extern bool bitmap_empty_p (const_sbitmap);
 236 extern void bitmap_clear (sbitmap);
 237 extern void bitmap_ones (sbitmap);
 238 extern void bitmap_vector_clear (sbitmap *, unsigned int);
 239 extern void bitmap_vector_ones (sbitmap *, unsigned int);
 240
 241 extern bool bitmap_ior_and_compl (sbitmap, const_sbitmap,
 242                                       const_sbitmap, const_sbitmap);
 243 extern void bitmap_and_compl (sbitmap, const_sbitmap, const_sbitmap);
 244 extern void bitmap_not (sbitmap, const_sbitmap);
 245 extern bool bitmap_or_and (sbitmap, const_sbitmap,
 246                                      const_sbitmap, const_sbitmap);
 247 extern bool bitmap_and_or (sbitmap, const_sbitmap,
 248                                      const_sbitmap, const_sbitmap);
 249 extern bool bitmap_intersect_p (const_sbitmap, const_sbitmap);
 250 extern bool bitmap_and (sbitmap, const_sbitmap, const_sbitmap);
 251 extern bool bitmap_ior (sbitmap, const_sbitmap, const_sbitmap);
 252 extern bool bitmap_xor (sbitmap, const_sbitmap, const_sbitmap);
 253 extern bool bitmap_subset_p (const_sbitmap, const_sbitmap);
 254
 255 extern int bitmap_first_set_bit (const_sbitmap);
 256 extern int bitmap_last_set_bit (const_sbitmap);
 257
 258 extern void debug_bitmap (const_sbitmap);
 259 extern sbitmap sbitmap_realloc (sbitmap, unsigned int);
 260 extern unsigned long sbitmap_popcount (const_sbitmap, unsigned long);
 261 #endif /* ! GCC_SBITMAP_H */