gcc/sbitmap.h

   1 /* Simple bitmaps.
   2    Copyright (C) 1999-2017 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 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 int n_bits;          /* Number of bits.  */
  88   unsigned int size;            /* Size in elements.  */
  89   SBITMAP_ELT_TYPE elms[1];     /* The elements.  */
  90 };
  91
  92 /* Return the set size needed for N elements.  */
  93 #define SBITMAP_SET_SIZE(N) (((N) + SBITMAP_ELT_BITS - 1) / SBITMAP_ELT_BITS)
  94
  95 /* Return the number of bits in BITMAP.  */
  96 #define SBITMAP_SIZE(BITMAP) ((BITMAP)->n_bits)
  97
  98 /* Test if bit number bitno in the bitmap is set.  */
  99 static inline SBITMAP_ELT_TYPE
 100 bitmap_bit_p (const_sbitmap map, int bitno)
 101 {
 102   size_t i = bitno / SBITMAP_ELT_BITS;
 103   unsigned int s = bitno % SBITMAP_ELT_BITS;
 104   return (map->elms[i] >> s) & (SBITMAP_ELT_TYPE) 1;
 105 }
 106
 107 /* Set bit number BITNO in the sbitmap MAP.  */
 108
 109 static inline void
 110 bitmap_set_bit (sbitmap map, int bitno)
 111 {
 112   map->elms[bitno / SBITMAP_ELT_BITS]
 113     |= (SBITMAP_ELT_TYPE) 1 << (bitno) % SBITMAP_ELT_BITS;
 114 }
 115
 116 /* Reset bit number BITNO in the sbitmap MAP.  */
 117
 118 static inline void
 119 bitmap_clear_bit (sbitmap map, int bitno)
 120 {
 121   map->elms[bitno / SBITMAP_ELT_BITS]
 122     &= ~((SBITMAP_ELT_TYPE) 1 << (bitno) % SBITMAP_ELT_BITS);
 123 }
 124
 125 /* The iterator for sbitmap.  */
 126 struct sbitmap_iterator {
 127   /* The pointer to the first word of the bitmap.  */
 128   const SBITMAP_ELT_TYPE *ptr;
 129
 130   /* The size of the bitmap.  */
 131   unsigned int size;
 132
 133   /* The current word index.  */
 134   unsigned int word_num;
 135
 136   /* The current bit index (not modulo SBITMAP_ELT_BITS).  */
 137   unsigned int bit_num;
 138
 139   /* The words currently visited.  */
 140   SBITMAP_ELT_TYPE word;
 141 };
 142
 143 /* Initialize the iterator I with sbitmap BMP and the initial index
 144    MIN.  */
 145
 146 static inline void
 147 bmp_iter_set_init (sbitmap_iterator *i, const_sbitmap bmp,
 148                    unsigned int min, unsigned *bit_no ATTRIBUTE_UNUSED)
 149 {
 150   i->word_num = min / (unsigned int) SBITMAP_ELT_BITS;
 151   i->bit_num = min;
 152   i->size = bmp->size;
 153   i->ptr = bmp->elms;
 154
 155   if (i->word_num >= i->size)
 156     i->word = 0;
 157   else
 158     i->word = (i->ptr[i->word_num]
 159                >> (i->bit_num % (unsigned int) SBITMAP_ELT_BITS));
 160 }
 161
 162 /* Return true if we have more bits to visit, in which case *N is set
 163    to the index of the bit to be visited.  Otherwise, return
 164    false.  */
 165
 166 static inline bool
 167 bmp_iter_set (sbitmap_iterator *i, unsigned int *n)
 168 {
 169   /* Skip words that are zeros.  */
 170   for (; i->word == 0; i->word = i->ptr[i->word_num])
 171     {
 172       i->word_num++;
 173
 174       /* If we have reached the end, break.  */
 175       if (i->word_num >= i->size)
 176         return false;
 177
 178       i->bit_num = i->word_num * SBITMAP_ELT_BITS;
 179     }
 180
 181   /* Skip bits that are zero.  */
 182   for (; (i->word & 1) == 0; i->word >>= 1)
 183     i->bit_num++;
 184
 185   *n = i->bit_num;
 186
 187   return true;
 188 }
 189
 190 /* Advance to the next bit.  */
 191
 192 static inline void
 193 bmp_iter_next (sbitmap_iterator *i, unsigned *bit_no ATTRIBUTE_UNUSED)
 194 {
 195   i->word >>= 1;
 196   i->bit_num++;
 197 }
 198
 199 /* Loop over all elements of SBITMAP, starting with MIN.  In each
 200    iteration, N is set to the index of the bit being visited.  ITER is
 201    an instance of sbitmap_iterator used to iterate the bitmap.  */
 202
 203 #ifndef EXECUTE_IF_SET_IN_BITMAP
 204 /* See bitmap.h for the other definition of EXECUTE_IF_SET_IN_BITMAP.  */
 205 #define EXECUTE_IF_SET_IN_BITMAP(BITMAP, MIN, BITNUM, ITER)     \
 206   for (bmp_iter_set_init (&(ITER), (BITMAP), (MIN), &(BITNUM)); \
 207        bmp_iter_set (&(ITER), &(BITNUM));                       \
 208        bmp_iter_next (&(ITER), &(BITNUM)))
 209 #endif
 210
 211 inline void sbitmap_free (sbitmap map)
 212 {
 213   free (map);
 214 }
 215
 216 inline void sbitmap_vector_free (sbitmap * vec)
 217 {
 218   free (vec);
 219 }
 220
 221 extern void dump_bitmap (FILE *, const_sbitmap);
 222 extern void debug_raw (const simple_bitmap_def &ref);
 223 extern void debug_raw (const simple_bitmap_def *ptr);
 224 extern void dump_bitmap_file (FILE *, const_sbitmap);
 225 extern void debug (const simple_bitmap_def &ref);
 226 extern void debug (const simple_bitmap_def *ptr);
 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_vector_alloc (unsigned int, unsigned int);
 231 extern sbitmap sbitmap_resize (sbitmap, unsigned int, int);
 232 extern void bitmap_copy (sbitmap, const_sbitmap);
 233 extern int bitmap_equal_p (const_sbitmap, const_sbitmap);
 234 extern unsigned int bitmap_count_bits (const_sbitmap);
 235 extern bool bitmap_empty_p (const_sbitmap);
 236 extern void bitmap_clear (sbitmap);
 237 extern void bitmap_clear_range (sbitmap, unsigned, unsigned);
 238 extern void bitmap_set_range (sbitmap, unsigned, unsigned);
 239 extern void bitmap_ones (sbitmap);
 240 extern void bitmap_vector_clear (sbitmap *, unsigned int);
 241 extern void bitmap_vector_ones (sbitmap *, unsigned int);
 242
 243 extern bool bitmap_ior_and_compl (sbitmap, const_sbitmap,
 244                                       const_sbitmap, const_sbitmap);
 245 extern void bitmap_and_compl (sbitmap, const_sbitmap, const_sbitmap);
 246 extern void bitmap_not (sbitmap, const_sbitmap);
 247 extern bool bitmap_or_and (sbitmap, const_sbitmap,
 248                                      const_sbitmap, const_sbitmap);
 249 extern bool bitmap_and_or (sbitmap, const_sbitmap,
 250                                      const_sbitmap, const_sbitmap);
 251 extern bool bitmap_intersect_p (const_sbitmap, const_sbitmap);
 252 extern bool bitmap_and (sbitmap, const_sbitmap, const_sbitmap);
 253 extern bool bitmap_ior (sbitmap, const_sbitmap, const_sbitmap);
 254 extern bool bitmap_xor (sbitmap, const_sbitmap, const_sbitmap);
 255 extern bool bitmap_subset_p (const_sbitmap, const_sbitmap);
 256
 257 extern int bitmap_first_set_bit (const_sbitmap);
 258 extern int bitmap_last_set_bit (const_sbitmap);
 259
 260 extern void debug_bitmap (const_sbitmap);
 261 extern sbitmap sbitmap_realloc (sbitmap, unsigned int);
 262
 263 /* a class that ties the lifetime of a sbitmap to its scope.  */
 264 class auto_sbitmap
 265 {
 266 public:
 267   explicit auto_sbitmap (unsigned int size) :
 268     m_bitmap (sbitmap_alloc (size)) {}
 269   ~auto_sbitmap () { sbitmap_free (m_bitmap); }
 270
 271   /* Allow calling sbitmap functions on our bitmap.  */
 272   operator sbitmap () { return m_bitmap; }
 273
 274 private:
 275   /* Prevent making a copy that refers to our sbitmap.  */
 276   auto_sbitmap (const auto_sbitmap &);
 277   auto_sbitmap &operator = (const auto_sbitmap &);
 278 #if __cplusplus >= 201103L
 279   auto_sbitmap (auto_sbitmap &&);
 280   auto_sbitmap &operator = (auto_sbitmap &&);
 281 #endif
 282
 283   /* The bitmap we are managing.  */
 284   sbitmap m_bitmap;
 285 };
 286
 287 #endif /* ! GCC_SBITMAP_H */