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/* Sparse array-based bitmaps.

   Copyright (C) 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

   Contributed by Daniel Berlin <dberlin@dberlin.org>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free

Software Foundation; either version 3, or (at your option) any later

version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "rtl.h"

#include "flags.h"

#include "obstack.h"

#include "ebitmap.h"

/* The ebitmap data structure is a sparse bitmap structure that works

   by having two pieces:

   1. An array of all nonzero words in the structures, organized as

   an array of HOST_WIDE_INT's.

   2. A non-sparse bitmap saying which bitmap words are present in the

   array.

   As a consequence of this representation, testing whether a bit

   exists in the bitmap is faster than linked-list bitmaps.  For bits

   in words that are all zero, the time to test is O(1).  For bits in

   words that exist, it requires O(n/sizeof(word)) time to perform the

   test (ignoring the one element cache).  It also has much better

   locality than linked-list bitmaps.

   To test whether a bit exists, we do the following:

   1. Test whether the word the bit would appear in exists in the

   bitmap (O(1) check of the mask).  If not, fail.

   2. Population count the mask up to the word containing the bit, to

   find the place in the array the word would be (popcount is cached,

   but this is just as slow as the linked-list bitmap)

   3. Test the word to see if the bit exists.

   Just like linked-list bitmaps, we cache the last element that has

   been tested in order to speed up common access patterns.

   Most of the other speedups are simply due to better locality of the

   single contiguous array.

   As would be expected in a structure like this, insertion into an

   empty word in the middle requires moving bits to make room for the

   new word.   As most operations that perform sets perform them in

   order, this is rarely a problem.  We also take advantage of the

   same element cache to make repeated sets to the same word O(1).

   Operations on the entire bitmap are also more efficient than linked

   list bitmaps, as they are all operating on contiguous memory, and

   can be easily vectorized.  They are all O(number of words) +

   O(number of bits that may end up in the destination), as the

   appropriate operation is first performed on the word mask, and then

   only those elements that may generate results are touched.

   Memory wise, the ebitmap starts out using less memory than the

   linked-list bitmap, but its size in memory is technically bounded

   by ((index of the highest bit set) / (size of a word) + (index of

   the highest bit set) / ((size of a word) * (size of a word))) This

   is because the mask is non-sparse.  The mask could be transformed

   into a sparse bitmap at the cost of making bit testing

   *theoretically* slower (real world numbers have not been computed

   yet as to whether it matters or not).  */

/* #define EBITMAP_DEBUGGING  */

/* Find the last set bit in ebitmap MAP.  */

int

ebitmap_last_set_bit (ebitmap map)

{

  unsigned int i = 0;

  ebitmap_iterator ebi;

  bool foundbit = false;

  /* This is not the fastest way to do this, we could simply look for

     the popcount, and start there, but this function is not used

     anywhere speed critical.  */

  EXECUTE_IF_SET_IN_EBITMAP (map, 0, i, ebi)

    {

      foundbit = true;

    }

  if (foundbit)

    return i;

  return -1;

}

/* Grow or shrink the internal word array for MAP to NEWSIZE

   elements.  */

static inline void

ebitmap_array_grow (ebitmap map, unsigned int newsize)

{

  if (newsize <= map->n_elts)

    {

      map->n_elts = newsize;

      return;

    }

  newsize += newsize / 4;

  map->n_elts = newsize;

  map->elts = XRESIZEVEC (EBITMAP_ELT_TYPE, map->elts, newsize);

}

/* Grow the internal word array for MAP so it is at least SIZE

   elements.  Will not shrink the array if it is already big

   enough.  */

static inline void

ebitmap_array_maybe_grow (ebitmap map, unsigned int size)

{

  if (size >= map->n_elts)

    ebitmap_array_grow (map, size + 1);

}

/* Retrieve the IDX'th element from the word array for MAP.  */

static inline EBITMAP_ELT_TYPE

ebitmap_array_get (ebitmap map, unsigned int idx)

{

  gcc_assert (idx < map->n_elts);

  return map->elts[idx];

}

/* Retrieve a pointer to the IDX'th element from the word array for

   MAP.  If the element index is greater than the size of the array,

   the array will be grown to the correct size.  */

static inline EBITMAP_ELT_TYPE *

ebitmap_array_grow_get (ebitmap map, unsigned int idx)

{

  if (idx >= map->n_elts)

    ebitmap_array_grow (map, idx + 1);

  return &map->elts[idx];

}

/* Initialize the internal word array for MAP, so that it is SIZE

   elements.  */

static inline void

ebitmap_array_init (ebitmap map, unsigned int size)

{

  if (size > 0)

    {

      map->elts = XNEWVEC (EBITMAP_ELT_TYPE, size);

      map->n_elts = size;

    }

  else

    {

      map->n_elts = 0;

      map->elts = NULL;

    }

}

/* Free the internal word array for MAP.  */

static inline void

ebitmap_array_clear (ebitmap map)

{

  if (map->elts)

    {

      free (map->elts);

      map->elts = NULL;

    }

  map->n_elts = 0;

}

/* Clear ebitmap MAP.  */

void

ebitmap_clear (ebitmap map)

{

  ebitmap_array_clear (map);

  sbitmap_zero (map->wordmask);

  map->wordmask = sbitmap_resize (map->wordmask, 1, 0);

  map->numwords = 0;

  map->cache = NULL;

  map->cacheindex = 0;

}

/* Allocate an ebitmap with enough room for SIZE bits to start out.  */

ebitmap

ebitmap_alloc (unsigned int size)

{

  ebitmap ret = XNEW (struct ebitmap_def);

  if (size == 0)

    size = EBITMAP_ELT_BITS;

  ebitmap_array_init (ret, (size + EBITMAP_ELT_BITS - 1) / EBITMAP_ELT_BITS);

  ret->wordmask = sbitmap_alloc_with_popcount (size);

  sbitmap_zero (ret->wordmask);

  ret->numwords = 0;

  ret->cache = NULL;

  ret->cacheindex = 0;

  return ret;

}

/* Clear BIT from ebitmap MAP.  */

void

ebitmap_clear_bit (ebitmap map, unsigned int bit)

{

  unsigned int wordindex = bit / EBITMAP_ELT_BITS;

  unsigned int eltwordindex = 0;

  unsigned int bitindex, shift;

  bool have_eltwordindex = false;

  EBITMAP_ELT_TYPE *elt_ptr;

  /* If the bit can't exist in our bitmap, just return.  */

  if (map->numwords == 0)

    return;

  if (wordindex >= map->wordmask->n_bits

      || !TEST_BIT (map->wordmask, wordindex))

    return;

  if (map->cache != NULL && map->cacheindex == wordindex)

    elt_ptr = map->cache;

  else

    {

      eltwordindex = sbitmap_popcount (map->wordmask, wordindex);

      elt_ptr = &map->elts[eltwordindex];

      have_eltwordindex = true;

    }

  bitindex = bit % EBITMAP_ELT_BITS;

  shift = bitindex;

  *(elt_ptr) &= ~(((EBITMAP_ELT_TYPE)1) << shift);

  /* Clear out the empty words.  */

  if (*(elt_ptr) == 0)

    {

      if (!have_eltwordindex)

        eltwordindex = sbitmap_popcount (map->wordmask, wordindex);

      if (map->cache != NULL)

        {

          if (map->cacheindex == wordindex)

            map->cache = NULL;

          else if (map->cacheindex > wordindex)

            map->cache = map->cache - 1;

        }

      RESET_BIT (map->wordmask, wordindex);

      memmove(&map->elts[eltwordindex], &map->elts[eltwordindex + 1],

              sizeof (EBITMAP_ELT_TYPE) * (map->numwords - eltwordindex));

      map->numwords--;

    }

}

/* Set BIT in ebitmap MAP.  */

void

ebitmap_set_bit (ebitmap map, unsigned int bit)

{

  unsigned int wordindex = bit / EBITMAP_ELT_BITS;

  unsigned int eltwordindex;

  unsigned int bitindex =   bit % EBITMAP_ELT_BITS;

  /* If we have this element cached, just set the bit in it.  */

  if (map->cache && map->cacheindex == wordindex)

    {

      (*map->cache) |= (EBITMAP_ELT_TYPE)1 << bitindex;

      return;

    }

  /* Resize the wordmask if necessary.  */

  if (wordindex >= map->wordmask->n_bits)

    map->wordmask = sbitmap_resize (map->wordmask, wordindex + 1, 0);

  /* Allocate a new word in the array and move whatever is in it's

     place, if necessary. */

  if (!TEST_BIT (map->wordmask, wordindex))

    {

      unsigned long count;

      unsigned int i;

      SET_BIT (map->wordmask, wordindex);

      count = sbitmap_popcount (map->wordmask, wordindex);

      gcc_assert (count <= map->numwords);

      for (i = map->numwords; i > count; i--)

        {

          EBITMAP_ELT_TYPE *newelt;

          newelt = ebitmap_array_grow_get (map, i);

          *newelt = ebitmap_array_get (map, i - 1);

        }

      map->numwords++;

      eltwordindex = count;

      ebitmap_array_maybe_grow (map, eltwordindex);

      map->elts[eltwordindex] = 0;

    }

  else

    {

      eltwordindex = sbitmap_popcount (map->wordmask, wordindex);

    }

  /* Set the actual bit.  */

  bitindex = bit % EBITMAP_ELT_BITS;

  map->elts[eltwordindex] |= (EBITMAP_ELT_TYPE)1 << bitindex;

  map->cache = &map->elts[eltwordindex];

  map->cacheindex = wordindex;

}

/* Return true if MAP contains BIT.  */

bool

ebitmap_bit_p (ebitmap map, unsigned int bit)

{

  unsigned int wordindex = bit / EBITMAP_ELT_BITS;

  unsigned int bitindex= bit % EBITMAP_ELT_BITS;

  /* Trivial empty ebitmap case.  */

  if (map->numwords == 0)

    return false;

  if (map->cache && map->cacheindex == wordindex)

    return ((*map->cache) >> bitindex) & 1;

  /* If the wordindex is greater than the size of the wordmask, *or*

     it's not set in the wordmask, this bit can't exist in our

     ebitmap.  */

  if (wordindex >= map->wordmask->n_bits

      || !TEST_BIT (map->wordmask, wordindex))

    return false;

  /* Find the bit and test it.  */

  map->cacheindex = wordindex;

  wordindex = sbitmap_popcount (map->wordmask, wordindex);

  map->cache = &map->elts[wordindex];

  return (map->elts[wordindex] >> bitindex) & 1;

}

/* Copy ebitmap SRC to DST.  */

void

ebitmap_copy (ebitmap dst, ebitmap src)

{

  /* Blow away any existing wordmask, and copy the new one.  */

  sbitmap_free (dst->wordmask);

  dst->wordmask = sbitmap_alloc_with_popcount (src->wordmask->n_bits);

  sbitmap_copy (dst->wordmask, src->wordmask);

  /* Make sure our destination array is big enough, and then copy the

     actual words.  */

  ebitmap_array_grow (dst, src->numwords);

  memcpy (dst->elts, src->elts,

          src->numwords * sizeof (EBITMAP_ELT_TYPE));

  dst->numwords = src->numwords;

  dst->cache = NULL;

}

/* Dump ebitmap BMAP to FILE.  */

void

dump_ebitmap (FILE *file, ebitmap bmap)

{

  unsigned int pos;

  unsigned int i;

  int res;

  unsigned int size;

  res = sbitmap_last_set_bit (bmap->wordmask);

  if (res == -1)

    size = 0;

  else

    size = (res + 1) * EBITMAP_ELT_BITS;

  fprintf (file, "n_words = %d, set = {", bmap->numwords);

  for (pos = 30, i = 0; i < size; i++)

    if (ebitmap_bit_p (bmap, i))

      {

        if (pos > 70)

          {

            fprintf (file, "\n  ");

            pos = 0;

          }

        pos += fprintf (file, "%d ", i);

      }

  fprintf (file, "}\n");

}

/* Dump ebitmap BMAP to stderr.  */

void

debug_ebitmap (ebitmap bmap)

{

  dump_ebitmap (stderr, bmap);

}

/* Perform the operation DST &= SRC.  */

void

ebitmap_and_into (ebitmap dst, ebitmap src)

{

  sbitmap_iterator sbi;

  unsigned int i;

  unsigned int neweltindex = 0;

  unsigned int dsteltindex = 0;

  unsigned int srceltindex = 0;

  gcc_assert (dst != src);

  dst->cache = NULL;

  /* Short circuit the empty bitmap cases.  */

  if (src->numwords == 0 || dst->numwords == 0)

    {

      ebitmap_clear (dst);

      return;

    }

  /* AND the masks, then walk the words that may actually appear in

     the result, AND'ing them.  */

  sbitmap_a_and_b (dst->wordmask, dst->wordmask, src->wordmask);

  EXECUTE_IF_SET_IN_SBITMAP (dst->wordmask, 0, i, sbi)

    {

      EBITMAP_ELT_TYPE tmpword = ebitmap_array_get (src, srceltindex++);

      tmpword &= ebitmap_array_get (dst, dsteltindex++);

      if (tmpword != 0)

        {

          EBITMAP_ELT_TYPE *dstplace;

          dstplace = ebitmap_array_grow_get (dst, neweltindex++);

          *dstplace = tmpword;

        }

      else

        RESET_BIT (dst->wordmask, i);

    }

#ifdef EBITMAP_DEBUGGING

  {

    unsigned int i;

    for (i = 0; i <  dst->numwords; i++)

      gcc_assert (dst->elts[i] != 0);

    sbitmap_verify_popcount (dst->wordmask);

    gcc_assert (sbitmap_popcount (dst->wordmask,

                                  dst->wordmask->n_bits) == dst->numwords);

  }

#endif

  dst->numwords = neweltindex;

}

/* Perform the operation DST = SRC1 & SRC2.  */

void

ebitmap_and (ebitmap dst, ebitmap src1, ebitmap src2)

{

  sbitmap_iterator sbi;

  unsigned int i;

  unsigned int neweltindex = 0;

  unsigned int src1eltindex = 0;

  unsigned int src2eltindex = 0;

  dst->cache = NULL;

  if (src1->numwords == 0 || src2->numwords == 0)

    {

      ebitmap_clear (dst);

      return;

    }

  dst->wordmask

    = sbitmap_resize (dst->wordmask,

                      MIN (src1->wordmask->n_bits, src2->wordmask->n_bits),

                      0);

  sbitmap_a_and_b (dst->wordmask, src1->wordmask, src2->wordmask);

  EXECUTE_IF_SET_IN_SBITMAP (dst->wordmask, 0, i, sbi)

    {

      bool src1hasword, src2hasword;

      src1hasword = TEST_BIT (src1->wordmask, i);

      src2hasword = TEST_BIT (src2->wordmask, i);

      if (src1hasword && src2hasword)

        {

          EBITMAP_ELT_TYPE tmpword = ebitmap_array_get (src1, src1eltindex++);

          tmpword &= ebitmap_array_get (src2, src2eltindex++);

          if (tmpword != 0)

            {

              EBITMAP_ELT_TYPE *dstplace;

              dstplace = ebitmap_array_grow_get (dst, neweltindex++);

              *dstplace = tmpword;

            }

          else

            RESET_BIT (dst->wordmask, i);

        }

      else if (src1hasword)

        src1eltindex++;

      else

        src2eltindex++;

    }

#ifdef EBITMAP_DEBUGGING

  {

    ebitmap_iterator ebi;

    unsigned int i;

    for (i = 0; i <  dst->numwords; i++)

      gcc_assert (dst->elts[i] != 0);

    EXECUTE_IF_SET_IN_EBITMAP (src1, 0, i, ebi)

      if (ebitmap_bit_p (src2, i))

        gcc_assert (ebitmap_bit_p (dst, i));

    for (i = 0; i <  dst->numwords; i++)

      gcc_assert (dst->elts[i] != 0);

    sbitmap_verify_popcount (dst->wordmask);

    gcc_assert (sbitmap_popcount (dst->wordmask,

                                  dst->wordmask->n_bits) == dst->numwords);

  }

#endif

  dst->numwords = neweltindex;

}

/* Perform the operation DST |= SRC.  Return true if any bits in DST

   changed.  */

bool

ebitmap_ior_into (ebitmap dst, ebitmap src)

{

  unsigned int dstsize = dst->wordmask->n_bits;

  unsigned int srcsize = src->wordmask->n_bits;

  sbitmap_iterator sbi;

  unsigned int i;

  sbitmap tempmask;

  unsigned int neweltindex = 0;

  unsigned int dsteltindex = 0;

  unsigned int srceltindex = 0;

  bool changed = false;

  EBITMAP_ELT_TYPE *newarray;

  unsigned int newarraysize;

#ifdef EBITMAP_DEBUGGING

  ebitmap dstcopy = ebitmap_alloc (1);

  ebitmap_copy (dstcopy, dst);

#endif

  dst->cache = NULL;

  if (dst == src)

    return false;

  if (dst->numwords == 0 && src->numwords != 0)

    {

      ebitmap_copy (dst, src);

      return true;

    }

  else if (src->numwords == 0)

    return false;

  /* We can do without the temp mask if it's faster, but it would mean

     touching more words in the actual dense vector.  */

  tempmask = sbitmap_alloc (MAX (srcsize, dstsize));

  sbitmap_zero (tempmask);

  if (srcsize == dstsize)

    {

      sbitmap_a_or_b (tempmask, dst->wordmask, src->wordmask);

    }

  else

    {

      dst->wordmask = sbitmap_resize (dst->wordmask, MAX (srcsize, dstsize),

                                      0);

      if (srcsize >= dstsize)

        {

          sbitmap_copy_n (tempmask, dst->wordmask, dst->wordmask->size);

          sbitmap_a_or_b (tempmask, tempmask, src->wordmask);

        }

      else

        {

          sbitmap_copy_n (tempmask, src->wordmask, src->wordmask->size);

          sbitmap_a_or_b (tempmask, tempmask, dst->wordmask);

        }

    }

  newarraysize = src->numwords + dst->numwords;

  newarray = XNEWVEC (EBITMAP_ELT_TYPE, newarraysize);

  EXECUTE_IF_SET_IN_SBITMAP (tempmask, 0, i, sbi)

    {

      bool dsthasword, srchasword;

      dsthasword = (i < dst->wordmask->n_bits

                    && TEST_BIT (dst->wordmask, i));

      srchasword = (i < src->wordmask->n_bits

                    && TEST_BIT (src->wordmask, i));

      if (dsthasword && srchasword)

        {

          EBITMAP_ELT_TYPE tmpword = ebitmap_array_get (src, srceltindex++);

          tmpword |= ebitmap_array_get (dst, dsteltindex);

          if (!changed)

            changed |= tmpword != ebitmap_array_get (dst, dsteltindex);

          dsteltindex++;

          newarray[neweltindex++] = tmpword;

        }

      else if (dsthasword)

        {

          newarray [neweltindex++] = ebitmap_array_get (dst, dsteltindex++);

        }

      else

        {

          newarray [neweltindex++] = ebitmap_array_get (src, srceltindex++);

          gcc_assert (i < dst->wordmask->n_bits);

          SET_BIT (dst->wordmask, i);

          changed |= true;

        }

    }

  sbitmap_free (tempmask);

  if (changed)

    {

      dst->numwords = neweltindex;

      free (dst->elts);

      dst->elts = newarray;

      dst->n_elts = newarraysize;

    }

  else

    free (newarray);

#ifdef EBITMAP_DEBUGGING

  {

    ebitmap_iterator ebi;

    unsigned int i;

    for (i = 0; i <  dst->numwords; i++)

      gcc_assert (dst->elts[i] != 0);

    EXECUTE_IF_SET_IN_EBITMAP (src, 0, i, ebi)

      gcc_assert (ebitmap_bit_p (dst, i));

    EXECUTE_IF_SET_IN_EBITMAP (dstcopy, 0, i, ebi)

      gcc_assert (ebitmap_bit_p (dst, i));

    sbitmap_verify_popcount (dst->wordmask);

    gcc_assert (changed == !ebitmap_equal_p (dst, dstcopy));

    gcc_assert (sbitmap_popcount (dst->wordmask,

                                  dst->wordmask->n_bits) == dst->numwords);

  }

#endif

  return changed;

}

/* Perform the operation DST = SRC1 | SRC2.  Return true if any bit

   in DST has changed.  */

bool

ebitmap_ior (ebitmap dst, ebitmap src1, ebitmap src2)

{

  unsigned int src1size = src1->wordmask->n_bits;

  unsigned int src2size = src2->wordmask->n_bits;

  sbitmap_iterator sbi;

  unsigned int i;

  sbitmap tempmask;

  unsigned int neweltindex = 0;

  unsigned int src1eltindex = 0;

  unsigned int src2eltindex = 0;

  bool changed = false;

  EBITMAP_ELT_TYPE *newarray;

  unsigned int newarraysize;

#ifdef EBITMAP_DEBUGGING

  ebitmap dstcopy = ebitmap_alloc (1);

  ebitmap_copy (dstcopy, dst);

#endif

  dst->cache = NULL;