X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/c837b82803719515392ef5c441cd1b94a6920f9d..31d3e510949227d55ed7e87c793b3ec571dffec3:/lib/ebitset.c?ds=sidebyside

diff --git a/lib/ebitset.c b/lib/ebitset.c
index 9751e4dd..cdbbe2de 100644
--- a/lib/ebitset.c
+++ b/lib/ebitset.c
@@ -1,10 +1,10 @@
 /* Functions to support expandable bitsets.
-   Copyright (C) 2002 Free Software Foundation, Inc.
+   Copyright (C) 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
    Contributed by Michael Hayes (m.hayes@elec.canterbury.ac.nz).
 
-   This program is free software; you can redistribute it and/or modify
+   This program 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 2 of the License, or
+   the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.
 
    This program is distributed in the hope that it will be useful,
@@ -13,17 +13,15 @@
    GNU General Public License for more details.
 
    You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software
-   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 
-*/
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
-#ifdef HAVE_CONFIG_H
-#include "config.h"
-#endif
+#include <config.h>
 
 #include "ebitset.h"
+
 #include "obstack.h"
 #include <stdlib.h>
+#include <string.h>
 
 /* This file implements expandable bitsets.  These bitsets can be of
    arbitrary length and are more efficient than arrays of bits for
@@ -37,12 +35,12 @@
    Bitsets are commonly empty so we need to ensure that this special
    case is fast.  A zero bitset is indicated when cdata is 0.  This is
    conservative since cdata may be non zero and the bitset may still
-   be zero. 
+   be zero.
 
    The bitset cache can be disabled either by setting cindex to
-   some large number or by setting csize to 0.  Here 
+   BITSET_WINDEX_MAX or by setting csize to 0.  Here
    we use the former approach since cindex needs to be updated whenever
-   cdata is changed.   
+   cdata is changed.
 */
 
 
@@ -51,7 +49,7 @@
 
 /* Number of bits stored in each element.  */
 #define EBITSET_ELT_BITS \
-  ((unsigned) (EBITSET_ELT_WORDS * BITSET_WORD_BITS))
+  ((unsigned int) (EBITSET_ELT_WORDS * BITSET_WORD_BITS))
 
 /* Ebitset element.  We use an array of bits.  */
 typedef struct ebitset_elt_struct
@@ -68,14 +66,6 @@ ebitset_elt;
 
 typedef ebitset_elt *ebitset_elts;
 
-/* Head of ebitset linked list.  */
-typedef struct ebitset_struct
-{
-  unsigned int size;		/* Number of elements.  */
-  ebitset_elts *elts;		/* Expanding array of pointers to elements.  */
-}
-*ebitset;
-
 
 /* Number of elements to initially allocate.  */
 
@@ -83,17 +73,6 @@ typedef struct ebitset_struct
 #define EBITSET_INITIAL_SIZE 2
 #endif
 
-/* Minimum number of elements to grow table.  */
-
-#ifndef EBITSET_GROW_SIZE
-#define EBITSET_GROW_SIZE 4
-#endif
-
-struct bitset_struct
-{
-  struct bbitset_struct b;
-  struct ebitset_struct e;
-};
 
 enum ebitset_find_mode
   { EBITSET_FIND, EBITSET_CREATE, EBITSET_SUBST };
@@ -102,49 +81,22 @@ static ebitset_elt ebitset_zero_elts[1]; /* Elements of all zero bits.  */
 
 /* Obstack to allocate bitset elements from.  */
 static struct obstack ebitset_obstack;
-static int ebitset_obstack_init = 0;
+static bool ebitset_obstack_init = false;
 static ebitset_elt *ebitset_free_list;	/* Free list of bitset elements.  */
 
-static void ebitset_elts_grow PARAMS ((bitset, unsigned int));
-static ebitset_elt *ebitset_elt_alloc PARAMS ((void));
-static ebitset_elt *ebitset_elt_calloc PARAMS ((void));
-static void ebitset_elt_add PARAMS ((bitset, ebitset_elt *, unsigned int));
-static void ebitset_elt_remove PARAMS ((bitset, unsigned int));
-static void ebitset_elt_free PARAMS ((ebitset_elt *));
-static ebitset_elt *ebitset_elt_find PARAMS ((bitset, bitset_windex,
-					      enum ebitset_find_mode));
-static ebitset_elt *ebitset_elt_last PARAMS ((bitset));
-static int ebitset_elt_zero_p PARAMS ((ebitset_elt *));
-
-static int ebitset_weed PARAMS ((bitset));
-static void ebitset_zero PARAMS ((bitset));
-static int ebitset_equal_p PARAMS ((bitset, bitset));
-static void ebitset_copy PARAMS ((bitset, bitset));
-static int ebitset_copy_compare PARAMS ((bitset, bitset));
-static void ebitset_set PARAMS ((bitset, bitset_bindex));
-static void ebitset_reset PARAMS ((bitset, bitset_bindex));
-static int ebitset_test PARAMS ((bitset, bitset_bindex));
-static int ebitset_size PARAMS ((bitset));
-static int ebitset_op1 PARAMS ((bitset, enum bitset_ops));
-static int ebitset_op2 PARAMS ((bitset, bitset, enum bitset_ops));
-static int ebitset_op3 PARAMS ((bitset, bitset, bitset, enum bitset_ops));
-static int ebitset_list PARAMS ((bitset, bitset_bindex *, bitset_bindex,
-				 bitset_bindex *));
-static int ebitset_reverse_list
-PARAMS ((bitset, bitset_bindex *, bitset_bindex, bitset_bindex *));
-static void ebitset_free PARAMS ((bitset));
-
+#define EBITSET_N_ELTS(N) (((N) + EBITSET_ELT_BITS - 1) / EBITSET_ELT_BITS)
 #define EBITSET_ELTS(BSET) ((BSET)->e.elts)
-#define EBITSET_SIZE(BSET) ((BSET)->e.size)
+#define EBITSET_SIZE(BSET) EBITSET_N_ELTS (BITSET_NBITS_ (BSET))
+#define EBITSET_ASIZE(BSET) ((BSET)->e.size)
 
 #define EBITSET_NEXT(ELT) ((ELT)->u.next)
 #define EBITSET_WORDS(ELT) ((ELT)->u.words)
 
 /* Disable bitset cache and mark BSET as being zero.  */
-#define EBITSET_OP_ZERO_SET(BSET) ((BSET)->b.cindex = BITSET_INDEX_MAX, \
-        (BSET)->b.cdata = 0)
+#define EBITSET_ZERO_SET(BSET) ((BSET)->b.cindex = BITSET_WINDEX_MAX, \
+	(BSET)->b.cdata = 0)
 
-#define EBITSET_CACHE_DISABLE(BSET)  ((BSET)->b.cindex = BITSET_INDEX_MAX)
+#define EBITSET_CACHE_DISABLE(BSET)  ((BSET)->b.cindex = BITSET_WINDEX_MAX)
 
 /* Disable bitset cache and mark BSET as being possibly non-zero.  */
 #define EBITSET_NONZERO_SET(BSET) \
@@ -152,38 +104,79 @@ static void ebitset_free PARAMS ((bitset));
 
 /* A conservative estimate of whether the bitset is zero.
    This is non-zero only if we know for sure that the bitset is zero.  */
-#define EBITSET_OP_ZERO_P(BSET) ((BSET)->b.cdata == 0)
+#define EBITSET_ZERO_P(BSET) ((BSET)->b.cdata == 0)
 
-/* Enable cache to point to element with table index EINDEX. 
+/* Enable cache to point to element with table index EINDEX.
    The element must exist.  */
 #define EBITSET_CACHE_SET(BSET, EINDEX) \
  ((BSET)->b.cindex = (EINDEX) * EBITSET_ELT_WORDS, \
   (BSET)->b.cdata = EBITSET_WORDS (EBITSET_ELTS (BSET) [EINDEX]))
 
+#undef min
+#undef max
+#define min(a, b) ((a) > (b) ? (b) : (a))
+#define max(a, b) ((a) > (b) ? (a) : (b))
 
-/* Grow the expandable table for BSET by SIZE elements.  */
-static void
-ebitset_elts_grow (bset, size)
-     bitset bset;
-     unsigned int size;
+static bitset_bindex
+ebitset_resize (bitset src, bitset_bindex n_bits)
 {
-  unsigned int oldsize;
-  unsigned int newsize;
+  bitset_windex oldsize;
+  bitset_windex newsize;
+
+  if (n_bits == BITSET_NBITS_ (src))
+    return n_bits;
 
-  oldsize = EBITSET_SIZE (bset);
-  newsize = oldsize + size;
+  oldsize = EBITSET_SIZE (src);
+  newsize = EBITSET_N_ELTS (n_bits);
 
-  EBITSET_ELTS (bset) = xrealloc (EBITSET_ELTS (bset),
-				  newsize * sizeof (ebitset_elt *));
-  EBITSET_SIZE (bset) = newsize;
+  if (oldsize < newsize)
+    {
+      bitset_windex size;
+
+      /* The bitset needs to grow.  If we already have enough memory
+	 allocated, then just zero what we need.  */
+      if (newsize > EBITSET_ASIZE (src))
+	{
+	  /* We need to allocate more memory.  When oldsize is
+	     non-zero this means that we are changing the size, so
+	     grow the bitset 25% larger than requested to reduce
+	     number of reallocations.  */
+
+	  if (oldsize == 0)
+	    size = newsize;
+	  else
+	    size = newsize + newsize / 4;
+
+	  EBITSET_ELTS (src)
+	    = realloc (EBITSET_ELTS (src), size * sizeof (ebitset_elt *));
+	  EBITSET_ASIZE (src) = size;
+	}
 
-  memset (EBITSET_ELTS (bset) + oldsize, 0, size * sizeof (ebitset_elt *));
+      memset (EBITSET_ELTS (src) + oldsize, 0,
+	      (newsize - oldsize) * sizeof (ebitset_elt *));
+    }
+  else
+    {
+      /* The bitset needs to shrink.  There's no point deallocating
+	 the memory unless it is shrinking by a reasonable amount.  */
+      if ((oldsize - newsize) >= oldsize / 2)
+	{
+	  EBITSET_ELTS (src)
+	    = realloc (EBITSET_ELTS (src), newsize * sizeof (ebitset_elt *));
+	  EBITSET_ASIZE (src) = newsize;
+	}
+
+      /* Need to prune any excess bits.  FIXME.  */
+    }
+
+  BITSET_NBITS_ (src) = n_bits;
+  return n_bits;
 }
 
 
 /* Allocate a ebitset element.  The bits are not cleared.  */
 static inline ebitset_elt *
-ebitset_elt_alloc ()
+ebitset_elt_alloc (void)
 {
   ebitset_elt *elt;
 
@@ -196,7 +189,7 @@ ebitset_elt_alloc ()
     {
       if (!ebitset_obstack_init)
 	{
-	  ebitset_obstack_init = 1;
+	  ebitset_obstack_init = true;
 
 	  /* Let particular systems override the size of a chunk.  */
 
@@ -214,15 +207,13 @@ ebitset_elt_alloc ()
 #define OBSTACK_CHUNK_FREE free
 #endif
 
-#if !defined(__GNUC__) || (__GNUC__ < 2)
+#if ! defined __GNUC__ || __GNUC__ < 2
 #define __alignof__(type) 0
 #endif
 
 	  obstack_specify_allocation (&ebitset_obstack, OBSTACK_CHUNK_SIZE,
 				      __alignof__ (ebitset_elt),
-				      (void *(*)PARAMS ((long)))
 				      OBSTACK_CHUNK_ALLOC,
-				      (void (*)PARAMS ((void *)))
 				      OBSTACK_CHUNK_FREE);
 	}
 
@@ -238,7 +229,7 @@ ebitset_elt_alloc ()
 
 /* Allocate a ebitset element.  The bits are cleared.  */
 static inline ebitset_elt *
-ebitset_elt_calloc ()
+ebitset_elt_calloc (void)
 {
   ebitset_elt *elt;
 
@@ -249,8 +240,7 @@ ebitset_elt_calloc ()
 
 
 static inline void
-ebitset_elt_free (elt)
-     ebitset_elt *elt;
+ebitset_elt_free (ebitset_elt *elt)
 {
   EBITSET_NEXT (elt) = ebitset_free_list;
   ebitset_free_list = elt;
@@ -259,9 +249,7 @@ ebitset_elt_free (elt)
 
 /* Remove element with index EINDEX from bitset BSET.  */
 static inline void
-ebitset_elt_remove (bset, eindex)
-     bitset bset;
-     unsigned int eindex;
+ebitset_elt_remove (bitset bset, bitset_windex eindex)
 {
   ebitset_elts *elts;
   ebitset_elt *elt;
@@ -277,10 +265,7 @@ ebitset_elt_remove (bset, eindex)
 
 /* Add ELT into elts at index EINDEX of bitset BSET.  */
 static inline void
-ebitset_elt_add (bset, elt, eindex)
-     bitset bset;
-     ebitset_elt *elt;
-     unsigned int eindex;
+ebitset_elt_add (bitset bset, ebitset_elt *elt, bitset_windex eindex)
 {
   ebitset_elts *elts;
 
@@ -290,33 +275,30 @@ ebitset_elt_add (bset, elt, eindex)
 }
 
 
-/* Return nonzero if all bits in an element are zero.  */
-static inline int
-ebitset_elt_zero_p (elt)
-     ebitset_elt *elt;
+/* Are all bits in an element zero?  */
+static inline bool
+ebitset_elt_zero_p (ebitset_elt *elt)
 {
   int i;
 
   for (i = 0; i < EBITSET_ELT_WORDS; i++)
     if (EBITSET_WORDS (elt)[i])
-      return 0;
+      return false;
 
-  return 1;
+  return true;
 }
 
 
 static ebitset_elt *
-ebitset_elt_find (bset, windex, mode)
-     bitset bset;
-     bitset_windex windex;
-     enum ebitset_find_mode mode;
+ebitset_elt_find (bitset bset, bitset_bindex bindex,
+		  enum ebitset_find_mode mode)
 {
   ebitset_elt *elt;
   bitset_windex size;
-  unsigned int eindex;
+  bitset_windex eindex;
   ebitset_elts *elts;
 
-  eindex = windex / EBITSET_ELT_WORDS;
+  eindex = bindex / EBITSET_ELT_BITS;
 
   elts = EBITSET_ELTS (bset);
   size = EBITSET_SIZE (bset);
@@ -337,26 +319,15 @@ ebitset_elt_find (bset, windex, mode)
 
   switch (mode)
     {
+    default:
+      abort ();
+
     case EBITSET_FIND:
       return 0;
 
     case EBITSET_CREATE:
       if (eindex >= size)
-	{
-	  unsigned int extra;
-
-	  extra = eindex - size + 1;
-
-	  /* We need to expand the table by EXTRA elements.  It may be
-	     better with large bitsets to grow the number of
-	     elements by some fraction of the current size otherwise
-	     we can spend a lot of time slowly increasing the size of the
-	     bitset.  */
-	  if (extra < EBITSET_GROW_SIZE)
-	    extra = EBITSET_GROW_SIZE;
-
-	  ebitset_elts_grow (bset, extra);
-	}
+	ebitset_resize (bset, bindex);
 
       /* Create a new element.  */
       elt = ebitset_elt_calloc ();
@@ -366,36 +337,19 @@ ebitset_elt_find (bset, windex, mode)
 
     case EBITSET_SUBST:
       return &ebitset_zero_elts[0];
-
-    default:
-      abort ();
     }
 }
 
 
-static inline ebitset_elt *
-ebitset_elt_last (bset)
-     bitset bset;
-{
-  ebitset_elts *elts;
-
-  elts = EBITSET_ELTS (bset);
-
-  /* Assume that have at least one element in elts.  */
-  return elts[EBITSET_SIZE (bset) - 1];
-}
-
-
 /* Weed out the zero elements from the elts.  */
-static inline int
-ebitset_weed (bset)
-     bitset bset;
+static inline bitset_windex
+ebitset_weed (bitset bset)
 {
   ebitset_elts *elts;
   bitset_windex j;
-  int count;
+  bitset_windex count;
 
-  if (EBITSET_OP_ZERO_P (bset))
+  if (EBITSET_ZERO_P (bset))
     return 0;
 
   elts = EBITSET_ELTS (bset);
@@ -406,7 +360,7 @@ ebitset_weed (bset)
 
       if (elt)
 	{
-	  if (elt && ebitset_elt_zero_p (elt))
+	  if (ebitset_elt_zero_p (elt))
 	    {
 	      ebitset_elt_remove (bset, j);
 	      count++;
@@ -419,9 +373,9 @@ ebitset_weed (bset)
   count = j - count;
   if (!count)
     {
-      /* All the bits are zero.  We could shrink the elts. 
+      /* All the bits are zero.  We could shrink the elts.
 	 For now just mark BSET as known to be zero.  */
-      EBITSET_OP_ZERO_SET (bset);
+      EBITSET_ZERO_SET (bset);
     }
   else
     EBITSET_NONZERO_SET (bset);
@@ -432,13 +386,12 @@ ebitset_weed (bset)
 
 /* Set all bits in the bitset to zero.  */
 static inline void
-ebitset_zero (bset)
-     bitset bset;
+ebitset_zero (bitset bset)
 {
   ebitset_elts *elts;
   bitset_windex j;
 
-  if (EBITSET_OP_ZERO_P (bset))
+  if (EBITSET_ZERO_P (bset))
     return;
 
   elts = EBITSET_ELTS (bset);
@@ -450,29 +403,27 @@ ebitset_zero (bset)
 	ebitset_elt_remove (bset, j);
     }
 
-  /* All the bits are zero.  We could shrink the elts. 
+  /* All the bits are zero.  We could shrink the elts.
      For now just mark BSET as known to be zero.  */
-  EBITSET_OP_ZERO_SET (bset);
+  EBITSET_ZERO_SET (bset);
 }
 
 
-static inline int
-ebitset_equal_p (dst, src)
-     bitset dst;
-     bitset src;
+static inline bool
+ebitset_equal_p (bitset dst, bitset src)
 {
   ebitset_elts *selts;
   ebitset_elts *delts;
   bitset_windex j;
 
   if (src == dst)
-    return 1;
+    return true;
 
   ebitset_weed (dst);
   ebitset_weed (src);
 
   if (EBITSET_SIZE (src) != EBITSET_SIZE (dst))
-    return 0;
+    return false;
 
   selts = EBITSET_ELTS (src);
   delts = EBITSET_ELTS (dst);
@@ -486,21 +437,19 @@ ebitset_equal_p (dst, src)
       if (!selt && !delt)
 	continue;
       if ((selt && !delt) || (!selt && delt))
-	return 0;
+	return false;
 
       for (i = 0; i < EBITSET_ELT_WORDS; i++)
 	if (EBITSET_WORDS (selt)[i] != EBITSET_WORDS (delt)[i])
-	  return 0;
+	  return false;
     }
-  return 1;
+  return true;
 }
 
 
 /* Copy bits from bitset SRC to bitset DST.  */
 static inline void
-ebitset_copy (dst, src)
-     bitset dst;
-     bitset src;
+ebitset_copy_ (bitset dst, bitset src)
 {
   ebitset_elts *selts;
   ebitset_elts *delts;
@@ -511,8 +460,8 @@ ebitset_copy (dst, src)
 
   ebitset_zero (dst);
 
-  if (EBITSET_SIZE (dst) < EBITSET_SIZE (src))
-    ebitset_elts_grow (dst, EBITSET_SIZE (src) - EBITSET_SIZE (dst));
+  if (BITSET_NBITS_ (dst) != BITSET_NBITS_ (src))
+    ebitset_resize (dst, BITSET_NBITS_ (src));
 
   selts = EBITSET_ELTS (src);
   delts = EBITSET_ELTS (dst);
@@ -534,49 +483,35 @@ ebitset_copy (dst, src)
 }
 
 
-/* Copy bits from bitset SRC to bitset DST.  Return non-zero if
+/* Copy bits from bitset SRC to bitset DST.  Return true if
    bitsets different.  */
-static inline int
-ebitset_copy_compare (dst, src)
-     bitset dst;
-     bitset src;
+static inline bool
+ebitset_copy_cmp (bitset dst, bitset src)
 {
   if (src == dst)
-    return 0;
+    return false;
 
-  if (EBITSET_OP_ZERO_P (dst))
+  if (EBITSET_ZERO_P (dst))
     {
-      ebitset_copy (dst, src);
-      return !EBITSET_OP_ZERO_P (src);
+      ebitset_copy_ (dst, src);
+      return !EBITSET_ZERO_P (src);
     }
 
   if (ebitset_equal_p (dst, src))
-    return 0;
+    return false;
 
-  ebitset_copy (dst, src);
-  return 1;
-}
-
-
-/* Return size in bits of bitset SRC.  */
-static int
-ebitset_size (src)
-     bitset src;
-{
-  /* Return current size of bitset in bits.  */
-  return EBITSET_SIZE (src) * EBITSET_ELT_BITS;
+  ebitset_copy_ (dst, src);
+  return true;
 }
 
 
 /* Set bit BITNO in bitset DST.  */
 static void
-ebitset_set (dst, bitno)
-     bitset dst;
-     bitset_bindex bitno;
+ebitset_set (bitset dst, bitset_bindex bitno)
 {
   bitset_windex windex = bitno / BITSET_WORD_BITS;
 
-  ebitset_elt_find (dst, windex, EBITSET_CREATE);
+  ebitset_elt_find (dst, bitno, EBITSET_CREATE);
 
   dst->b.cdata[windex - dst->b.cindex] |=
     (bitset_word) 1 << (bitno % BITSET_WORD_BITS);
@@ -585,43 +520,37 @@ ebitset_set (dst, bitno)
 
 /* Reset bit BITNO in bitset DST.  */
 static void
-ebitset_reset (dst, bitno)
-     bitset dst;
-     bitset_bindex bitno;
+ebitset_reset (bitset dst, bitset_bindex bitno)
 {
   bitset_windex windex = bitno / BITSET_WORD_BITS;
 
-  if (!ebitset_elt_find (dst, windex, EBITSET_FIND))
+  if (!ebitset_elt_find (dst, bitno, EBITSET_FIND))
     return;
 
   dst->b.cdata[windex - dst->b.cindex] &=
     ~((bitset_word) 1 << (bitno % BITSET_WORD_BITS));
 
-  /* If all the data is zero, perhaps we should remove it now... 
+  /* If all the data is zero, perhaps we should remove it now...
      However, there is a good chance that the element will be needed
      again soon.  */
 }
 
 
 /* Test bit BITNO in bitset SRC.  */
-static int
-ebitset_test (src, bitno)
-     bitset src;
-     bitset_bindex bitno;
+static bool
+ebitset_test (bitset src, bitset_bindex bitno)
 {
   bitset_windex windex = bitno / BITSET_WORD_BITS;
 
-  if (!ebitset_elt_find (src, windex, EBITSET_FIND))
-    return 0;
-
-  return (src->b.
-	  cdata[windex - src->b.cindex] >> (bitno % BITSET_WORD_BITS)) & 1;
+  return (ebitset_elt_find (src, bitno, EBITSET_FIND)
+	  && ((src->b.cdata[windex - src->b.cindex]
+	       >> (bitno % BITSET_WORD_BITS))
+	      & 1));
 }
 
 
 static void
-ebitset_free (bset)
-     bitset bset;
+ebitset_free (bitset bset)
 {
   ebitset_zero (bset);
   free (EBITSET_ELTS (bset));
@@ -631,12 +560,9 @@ ebitset_free (bset)
 /* Find list of up to NUM bits set in BSET starting from and including
  *NEXT and store in array LIST.  Return with actual number of bits
  found and with *NEXT indicating where search stopped.  */
-static int
-ebitset_reverse_list (bset, list, num, next)
-     bitset bset;
-     bitset_bindex *list;
-     bitset_bindex num;
-     bitset_bindex *next;
+static bitset_bindex
+ebitset_list_reverse (bitset bset, bitset_bindex *list,
+		      bitset_bindex num, bitset_bindex *next)
 {
   bitset_bindex n_bits;
   bitset_bindex bitno;
@@ -644,13 +570,13 @@ ebitset_reverse_list (bset, list, num, next)
   unsigned int bcount;
   bitset_bindex boffset;
   bitset_windex windex;
-  unsigned int eindex;
+  bitset_windex eindex;
   bitset_windex woffset;
   bitset_bindex count;
   bitset_windex size;
   ebitset_elts *elts;
 
-  if (EBITSET_OP_ZERO_P (bset))
+  if (EBITSET_ZERO_P (bset))
     return 0;
 
   size = EBITSET_SIZE (bset);
@@ -678,12 +604,11 @@ ebitset_reverse_list (bset, list, num, next)
   do
     {
       ebitset_elt *elt;
+      bitset_word *srcp;
 
       elt = elts[eindex];
       if (elt)
 	{
-	  bitset_word *srcp;
-
 	  srcp = EBITSET_WORDS (elt);
 
 	  do
@@ -705,15 +630,13 @@ ebitset_reverse_list (bset, list, num, next)
 		    }
 		  word <<= 1;
 		}
-
 	      boffset -= BITSET_WORD_BITS;
 	      bcount = BITSET_WORD_BITS - 1;
 	    }
 	  while (woffset--);
-
-	  woffset = EBITSET_ELT_WORDS;
 	}
 
+      woffset = EBITSET_ELT_WORDS - 1;
       boffset = eindex * EBITSET_ELT_BITS - BITSET_WORD_BITS;
     }
   while (eindex--);
@@ -726,23 +649,20 @@ ebitset_reverse_list (bset, list, num, next)
 /* Find list of up to NUM bits set in BSET starting from and including
  *NEXT and store in array LIST.  Return with actual number of bits
  found and with *NEXT indicating where search stopped.  */
-static int
-ebitset_list (bset, list, num, next)
-     bitset bset;
-     bitset_bindex *list;
-     bitset_bindex num;
-     bitset_bindex *next;
+static bitset_bindex
+ebitset_list (bitset bset, bitset_bindex *list,
+	      bitset_bindex num, bitset_bindex *next)
 {
   bitset_bindex bitno;
   bitset_windex windex;
-  unsigned int eindex;
+  bitset_windex eindex;
   bitset_bindex count;
   bitset_windex size;
   ebitset_elt *elt;
   bitset_word word;
   ebitset_elts *elts;
 
-  if (EBITSET_OP_ZERO_P (bset))
+  if (EBITSET_ZERO_P (bset))
     return 0;
 
   bitno = *next;
@@ -763,7 +683,7 @@ ebitset_list (bset, list, num, next)
 	  bitset_word *srcp = EBITSET_WORDS (elt);
 
 	  windex = bitno / BITSET_WORD_BITS;
-	  woffset = eindex / EBITSET_ELT_WORDS;
+	  woffset = eindex * EBITSET_ELT_WORDS;
 
 	  for (; (windex - woffset) < EBITSET_ELT_WORDS; windex++)
 	    {
@@ -809,6 +729,48 @@ ebitset_list (bset, list, num, next)
 	{
 	  /* The coast is clear, plant boot!  */
 
+#if EBITSET_ELT_WORDS == 2
+	  word = srcp[0];
+	  if (word)
+	    {
+	      if (!(word & 0xffff))
+		{
+		  word >>= 16;
+		  bitno += 16;
+		}
+	      if (!(word & 0xff))
+		{
+		  word >>= 8;
+		  bitno += 8;
+		}
+	      for (; word; bitno++)
+		{
+		  if (word & 1)
+		    list[count++] = bitno;
+		  word >>= 1;
+		}
+	    }
+	  windex++;
+	  bitno = windex * BITSET_WORD_BITS;
+
+	  word = srcp[1];
+	  if (word)
+	    {
+	      if (!(word & 0xffff))
+		{
+		  word >>= 16;
+		  bitno += 16;
+		}
+	      for (; word; bitno++)
+		{
+		  if (word & 1)
+		    list[count++] = bitno;
+		  word >>= 1;
+		}
+	    }
+	  windex++;
+	  bitno = windex * BITSET_WORD_BITS;
+#else
 	  for (i = 0; i < EBITSET_ELT_WORDS; i++, windex++)
 	    {
 	      bitno = windex * BITSET_WORD_BITS;
@@ -834,6 +796,7 @@ ebitset_list (bset, list, num, next)
 		    }
 		}
 	    }
+#endif
 	}
       else
 	{
@@ -866,160 +829,202 @@ ebitset_list (bset, list, num, next)
 }
 
 
-static int
-ebitset_op1 (dst, op)
-     bitset dst;
-     enum bitset_ops op;
+/* Ensure that any unused bits within the last element are clear.  */
+static inline void
+ebitset_unused_clear (bitset dst)
 {
-  bitset_windex j;
-  ebitset_elt *elt;
+  unsigned int last_bit;
+  bitset_bindex n_bits;
 
-  switch (op)
+  n_bits = BITSET_NBITS_ (dst);
+  last_bit = n_bits % EBITSET_ELT_BITS;
+
+  if (last_bit)
     {
-    case BITSET_OP_ZERO:
-      ebitset_zero (dst);
-      return 1;
+      bitset_windex eindex;
+      ebitset_elts *elts;
+      ebitset_elt *elt;
+
+      elts = EBITSET_ELTS (dst);
 
-    case BITSET_OP_ONES:
-      for (j = 0; j < EBITSET_SIZE (dst); j++)
+      eindex = n_bits / EBITSET_ELT_BITS;
+
+      elt = elts[eindex];
+      if (elt)
 	{
-	  /* Create new elements if they cannot be found.  Perhaps
-	     we should just add pointers to a ones element.  */
-	  elt =
-	    ebitset_elt_find (dst, j * EBITSET_ELT_WORDS, EBITSET_CREATE);
-	  memset (EBITSET_WORDS (elt), -1, sizeof (EBITSET_WORDS (elt)));
-	}
-      break;
+	  bitset_windex windex;
+	  bitset_windex woffset;
+	  bitset_word *srcp = EBITSET_WORDS (elt);
 
-    case BITSET_OP_EMPTY_P:
-      return !ebitset_weed (dst);
+	  windex = n_bits / BITSET_WORD_BITS;
+	  woffset = eindex * EBITSET_ELT_WORDS;
 
-    default:
-      abort ();
+	  srcp[windex - woffset] &= ((bitset_word) 1 << last_bit) - 1;
+	  windex++;
+	  for (; (windex - woffset) < EBITSET_ELT_WORDS; windex++)
+	    srcp[windex - woffset] = 0;
+	}
     }
+}
+
 
+static void
+ebitset_ones (bitset dst)
+{
+  bitset_windex j;
+  ebitset_elt *elt;
+
+  for (j = 0; j < EBITSET_SIZE (dst); j++)
+    {
+      /* Create new elements if they cannot be found.  Perhaps
+	 we should just add pointers to a ones element?  */
+      elt =
+	ebitset_elt_find (dst, j * EBITSET_ELT_BITS, EBITSET_CREATE);
+      memset (EBITSET_WORDS (elt), -1, sizeof (EBITSET_WORDS (elt)));
+    }
   EBITSET_NONZERO_SET (dst);
+  ebitset_unused_clear (dst);
+}
+
+
+static bool
+ebitset_empty_p (bitset dst)
+{
+  ebitset_elts *elts;
+  bitset_windex j;
+
+  if (EBITSET_ZERO_P (dst))
+    return 1;
+
+  elts = EBITSET_ELTS (dst);
+  for (j = 0; j < EBITSET_SIZE (dst); j++)
+    {
+      ebitset_elt *elt = elts[j];
+
+      if (elt)
+	{
+	  if (!ebitset_elt_zero_p (elt))
+	    return 0;
+	  /* Do some weeding as we go.  */
+	  ebitset_elt_remove (dst, j);
+	}
+    }
+
+  /* All the bits are zero.  We could shrink the elts.
+     For now just mark DST as known to be zero.  */
+  EBITSET_ZERO_SET (dst);
   return 1;
 }
 
 
-static int
-ebitset_op2 (dst, src, op)
-     bitset dst;
-     bitset src;
-     enum bitset_ops op;
+static void
+ebitset_not (bitset dst, bitset src)
 {
+  unsigned int i;
   ebitset_elt *selt;
   ebitset_elt *delt;
-  unsigned int i;
   bitset_windex j;
 
-  switch (op)
+  ebitset_resize (dst, BITSET_NBITS_ (src));
+
+  for (j = 0; j < EBITSET_SIZE (src); j++)
     {
-    case BITSET_OP_COPY:
-      ebitset_copy (dst, src);
-      break;
+      /* Create new elements for dst if they cannot be found
+	 or substitute zero elements if src elements not found.  */
+      selt =
+	ebitset_elt_find (dst, j * EBITSET_ELT_BITS, EBITSET_SUBST);
+      delt =
+	ebitset_elt_find (dst, j * EBITSET_ELT_BITS, EBITSET_CREATE);
 
-    case BITSET_OP_NOT:
-      for (j = 0; j < EBITSET_SIZE (src); j++)
-	{
-	  /* Create new elements for dst if they cannot be found
-	     or substitute zero elements if src elements not found.  */
-	  selt =
-	    ebitset_elt_find (dst, j * EBITSET_ELT_WORDS, EBITSET_SUBST);
-	  delt =
-	    ebitset_elt_find (dst, j * EBITSET_ELT_WORDS, EBITSET_CREATE);
-
-	  for (i = 0; i < EBITSET_ELT_WORDS; i++)
-	    EBITSET_WORDS (delt)[i] = ~EBITSET_WORDS (selt)[i];
-	}
-      break;
-
-      /* Return 1 if DST == SRC.  */
-    case BITSET_OP_EQUAL_P:
-      return ebitset_equal_p (dst, src);
-
-      /* Return 1 if DST == DST | SRC.  */
-    case BITSET_OP_SUBSET_P:
-      {
-	ebitset_elts *selts;
-	ebitset_elts *delts;
-	bitset_windex ssize;
-	bitset_windex dsize;
-
-	selts = EBITSET_ELTS (src);
-	delts = EBITSET_ELTS (dst);
-
-	ssize = EBITSET_SIZE (src);
-	dsize = EBITSET_SIZE (dst);
-
-	for (j = 0; j < ssize; j++)
-	  {
-	    selt = j < ssize ? selts[j] : 0;
-	    delt = j < dsize ? delts[j] : 0;
-
-	    if (!selt && !delt)
-	      continue;
-
-	    if (!selt)
-	      selt = &ebitset_zero_elts[0];
-	    if (!delt)
-	      delt = &ebitset_zero_elts[0];
-
-	    for (i = 0; i < EBITSET_ELT_WORDS; i++)
-	      if (EBITSET_WORDS (delt)[i]
-		  != (EBITSET_WORDS (selt)[i] | EBITSET_WORDS (delt)[i]))
-		return 0;
-	  }
-	return 1;
-      }
-      break;
-
-      /* Return 1 if DST & SRC == 0.  */
-    case BITSET_OP_DISJOINT_P:
-      {
-	ebitset_elts *selts;
-	ebitset_elts *delts;
-	bitset_windex ssize;
-	bitset_windex dsize;
-
-	selts = EBITSET_ELTS (src);
-	delts = EBITSET_ELTS (dst);
-
-	ssize = EBITSET_SIZE (src);
-	dsize = EBITSET_SIZE (dst);
-
-	for (j = 0; j < ssize; j++)
-	  {
-	    selt = j < ssize ? selts[j] : 0;
-	    delt = j < dsize ? delts[j] : 0;
-
-	    if (!selt || !delt)
-	      continue;
-
-	    for (i = 0; i < EBITSET_ELT_WORDS; i++)
-	      if ((EBITSET_WORDS (selt)[i] & EBITSET_WORDS (delt)[i]))
-		return 0;
-	  }
-	return 1;
-      }
-      break;
+      for (i = 0; i < EBITSET_ELT_WORDS; i++)
+	EBITSET_WORDS (delt)[i] = ~EBITSET_WORDS (selt)[i];
+    }
+  EBITSET_NONZERO_SET (dst);
+  ebitset_unused_clear (dst);
+}
 
-    default:
-      abort ();
+
+/* Is DST == DST | SRC?  */
+static bool
+ebitset_subset_p (bitset dst, bitset src)
+{
+  bitset_windex j;
+  ebitset_elts *selts;
+  ebitset_elts *delts;
+  bitset_windex ssize;
+  bitset_windex dsize;
+
+  selts = EBITSET_ELTS (src);
+  delts = EBITSET_ELTS (dst);
+
+  ssize = EBITSET_SIZE (src);
+  dsize = EBITSET_SIZE (dst);
+
+  for (j = 0; j < ssize; j++)
+    {
+      unsigned int i;
+      ebitset_elt *selt;
+      ebitset_elt *delt;
+
+      selt = j < ssize ? selts[j] : 0;
+      delt = j < dsize ? delts[j] : 0;
+
+      if (!selt && !delt)
+	continue;
+
+      if (!selt)
+	selt = &ebitset_zero_elts[0];
+      if (!delt)
+	delt = &ebitset_zero_elts[0];
+
+      for (i = 0; i < EBITSET_ELT_WORDS; i++)
+	if (EBITSET_WORDS (delt)[i]
+	    != (EBITSET_WORDS (selt)[i] | EBITSET_WORDS (delt)[i]))
+	  return false;
     }
+  return true;
+}
 
-  EBITSET_NONZERO_SET (dst);
-  return 1;
+
+/* Is DST & SRC == 0?  */
+static bool
+ebitset_disjoint_p (bitset dst, bitset src)
+{
+  bitset_windex j;
+  ebitset_elts *selts;
+  ebitset_elts *delts;
+  bitset_windex ssize;
+  bitset_windex dsize;
+
+  selts = EBITSET_ELTS (src);
+  delts = EBITSET_ELTS (dst);
+
+  ssize = EBITSET_SIZE (src);
+  dsize = EBITSET_SIZE (dst);
+
+  for (j = 0; j < ssize; j++)
+    {
+      unsigned int i;
+      ebitset_elt *selt;
+      ebitset_elt *delt;
+
+      selt = j < ssize ? selts[j] : 0;
+      delt = j < dsize ? delts[j] : 0;
+
+      if (!selt || !delt)
+	continue;
+
+      for (i = 0; i < EBITSET_ELT_WORDS; i++)
+	if ((EBITSET_WORDS (selt)[i] & EBITSET_WORDS (delt)[i]))
+	  return false;
+    }
+  return true;
 }
 
 
-static int
-ebitset_op3 (dst, src1, src2, op)
-     bitset dst;
-     bitset src1;
-     bitset src2;
-     enum bitset_ops op;
+
+static bool
+ebitset_op3_cmp (bitset dst, bitset src1, bitset src2, enum bitset_ops op)
 {
   bitset_windex ssize1;
   bitset_windex ssize2;
@@ -1031,40 +1036,11 @@ ebitset_op3 (dst, src1, src2, op)
   bitset_word *srcp1;
   bitset_word *srcp2;
   bitset_word *dstp;
-  int changed = 0;
+  bool changed = false;
   unsigned int i;
   bitset_windex j;
 
-  /* Fast track common, simple cases.  */
-  if (EBITSET_OP_ZERO_P (src2))
-    {
-      if (op == BITSET_OP_AND)
-	{
-	  ebitset_weed (dst);
-	  changed = EBITSET_OP_ZERO_P (dst);
-	  ebitset_zero (dst);
-	  return changed;
-	}
-      else if (op == BITSET_OP_ANDN || op == BITSET_OP_OR
-	       || op == BITSET_OP_XOR)
-	{
-	  return ebitset_copy_compare (dst, src1);
-	}
-    }
-  else if (EBITSET_OP_ZERO_P (src1))
-    {
-      if (op == BITSET_OP_AND || op == BITSET_OP_ANDN)
-	{
-	  ebitset_weed (dst);
-	  changed = EBITSET_OP_ZERO_P (dst);
-	  ebitset_zero (dst);
-	  return changed;
-	}
-      else if (op == BITSET_OP_OR || op == BITSET_OP_XOR)
-	{
-	  return ebitset_copy_compare (dst, src2);
-	}
-    }
+  ebitset_resize (dst, max (BITSET_NBITS_ (src1), BITSET_NBITS_ (src2)));
 
   ssize1 = EBITSET_SIZE (src1);
   ssize2 = EBITSET_SIZE (src2);
@@ -1073,9 +1049,6 @@ ebitset_op3 (dst, src1, src2, op)
   if (size < ssize2)
     size = ssize2;
 
-  if (size > dsize)
-    ebitset_elts_grow (dst, size - dsize);
-
   selts1 = EBITSET_ELTS (src1);
   selts2 = EBITSET_ELTS (src2);
   delts = EBITSET_ELTS (dst);
@@ -1094,7 +1067,7 @@ ebitset_op3 (dst, src1, src2, op)
 	{
 	  if (delt)
 	    {
-	      changed = 1;
+	      changed = true;
 	      ebitset_elt_remove (dst, j);
 	    }
 	  continue;
@@ -1114,6 +1087,9 @@ ebitset_op3 (dst, src1, src2, op)
       dstp = EBITSET_WORDS (delt);
       switch (op)
 	{
+	default:
+	  abort ();
+
 	case BITSET_OP_OR:
 	  for (i = 0; i < EBITSET_ELT_WORDS; i++, dstp++)
 	    {
@@ -1121,7 +1097,7 @@ ebitset_op3 (dst, src1, src2, op)
 
 	      if (*dstp != tmp)
 		{
-		  changed = 1;
+		  changed = true;
 		  *dstp = tmp;
 		}
 	    }
@@ -1134,7 +1110,7 @@ ebitset_op3 (dst, src1, src2, op)
 
 	      if (*dstp != tmp)
 		{
-		  changed = 1;
+		  changed = true;
 		  *dstp = tmp;
 		}
 	    }
@@ -1147,7 +1123,7 @@ ebitset_op3 (dst, src1, src2, op)
 
 	      if (*dstp != tmp)
 		{
-		  changed = 1;
+		  changed = true;
 		  *dstp = tmp;
 		}
 	    }
@@ -1160,14 +1136,11 @@ ebitset_op3 (dst, src1, src2, op)
 
 	      if (*dstp != tmp)
 		{
-		  changed = 1;
+		  changed = true;
 		  *dstp = tmp;
 		}
 	    }
 	  break;
-
-	default:
-	  abort ();
 	}
 
       if (!ebitset_elt_zero_p (delt))
@@ -1185,7 +1158,7 @@ ebitset_op3 (dst, src1, src2, op)
     {
       ebitset_elt *delt;
 
-      changed = 1;
+      changed = true;
 
       delt = delts[j];
 
@@ -1198,65 +1171,194 @@ ebitset_op3 (dst, src1, src2, op)
 }
 
 
+static bool
+ebitset_and_cmp (bitset dst, bitset src1, bitset src2)
+{
+  bool changed;
+
+  if (EBITSET_ZERO_P (src2))
+    {
+      ebitset_weed (dst);
+      changed = EBITSET_ZERO_P (dst);
+      ebitset_zero (dst);
+      return changed;
+    }
+  else if (EBITSET_ZERO_P (src1))
+    {
+      ebitset_weed (dst);
+      changed = EBITSET_ZERO_P (dst);
+      ebitset_zero (dst);
+      return changed;
+    }
+  return ebitset_op3_cmp (dst, src1, src2, BITSET_OP_AND);
+}
+
+
+static void
+ebitset_and (bitset dst, bitset src1, bitset src2)
+{
+  ebitset_and_cmp (dst, src1, src2);
+}
+
+
+static bool
+ebitset_andn_cmp (bitset dst, bitset src1, bitset src2)
+{
+  bool changed;
+
+  if (EBITSET_ZERO_P (src2))
+    {
+      return ebitset_copy_cmp (dst, src1);
+    }
+  else if (EBITSET_ZERO_P (src1))
+    {
+      ebitset_weed (dst);
+      changed = EBITSET_ZERO_P (dst);
+      ebitset_zero (dst);
+      return changed;
+    }
+  return ebitset_op3_cmp (dst, src1, src2, BITSET_OP_ANDN);
+}
+
+
+static void
+ebitset_andn (bitset dst, bitset src1, bitset src2)
+{
+  ebitset_andn_cmp (dst, src1, src2);
+}
+
+
+static bool
+ebitset_or_cmp (bitset dst, bitset src1, bitset src2)
+{
+  if (EBITSET_ZERO_P (src2))
+    {
+      return ebitset_copy_cmp (dst, src1);
+    }
+  else if (EBITSET_ZERO_P (src1))
+    {
+      return ebitset_copy_cmp (dst, src2);
+    }
+  return ebitset_op3_cmp (dst, src1, src2, BITSET_OP_OR);
+}
+
+
+static void
+ebitset_or (bitset dst, bitset src1, bitset src2)
+{
+  ebitset_or_cmp (dst, src1, src2);
+}
+
+
+static bool
+ebitset_xor_cmp (bitset dst, bitset src1, bitset src2)
+{
+  if (EBITSET_ZERO_P (src2))
+    {
+      return ebitset_copy_cmp (dst, src1);
+    }
+  else if (EBITSET_ZERO_P (src1))
+    {
+      return ebitset_copy_cmp (dst, src2);
+    }
+  return ebitset_op3_cmp (dst, src1, src2, BITSET_OP_XOR);
+}
+
+
+static void
+ebitset_xor (bitset dst, bitset src1, bitset src2)
+{
+  ebitset_xor_cmp (dst, src1, src2);
+}
+
+
+static void
+ebitset_copy (bitset dst, bitset src)
+{
+  if (BITSET_COMPATIBLE_ (dst, src))
+      ebitset_copy_ (dst, src);
+  else
+      bitset_copy_ (dst, src);
+}
+
+
 /* Vector of operations for linked-list bitsets.  */
-struct bitset_ops_struct ebitset_ops = {
+struct bitset_vtable ebitset_vtable = {
   ebitset_set,
   ebitset_reset,
+  bitset_toggle_,
   ebitset_test,
-  ebitset_size,
-  ebitset_op1,
-  ebitset_op2,
-  ebitset_op3,
-  bitset_op4,
+  ebitset_resize,
+  bitset_size_,
+  bitset_count_,
+  ebitset_empty_p,
+  ebitset_ones,
+  ebitset_zero,
+  ebitset_copy,
+  ebitset_disjoint_p,
+  ebitset_equal_p,
+  ebitset_not,
+  ebitset_subset_p,
+  ebitset_and,
+  ebitset_and_cmp,
+  ebitset_andn,
+  ebitset_andn_cmp,
+  ebitset_or,
+  ebitset_or_cmp,
+  ebitset_xor,
+  ebitset_xor_cmp,
+  bitset_and_or_,
+  bitset_and_or_cmp_,
+  bitset_andn_or_,
+  bitset_andn_or_cmp_,
+  bitset_or_and_,
+  bitset_or_and_cmp_,
   ebitset_list,
-  ebitset_reverse_list,
+  ebitset_list_reverse,
   ebitset_free,
   BITSET_TABLE
 };
 
 
 /* Return size of initial structure.  */
-int
-ebitset_bytes (n_bits)
-     bitset_bindex n_bits ATTRIBUTE_UNUSED;
+size_t
+ebitset_bytes (bitset_bindex n_bits ATTRIBUTE_UNUSED)
 {
-  return sizeof (struct bitset_struct);
+  return sizeof (struct ebitset_struct);
 }
 
 
 /* Initialize a bitset.  */
 
 bitset
-ebitset_init (bset, n_bits)
-     bitset bset;
-     bitset_bindex n_bits;
+ebitset_init (bitset bset, bitset_bindex n_bits)
 {
-  unsigned int size;
+  bitset_windex size;
 
-  bset->b.ops = &ebitset_ops;
+  bset->b.vtable = &ebitset_vtable;
 
   bset->b.csize = EBITSET_ELT_WORDS;
 
-  EBITSET_OP_ZERO_SET (bset);
+  EBITSET_ZERO_SET (bset);
 
   size = n_bits ? (n_bits + EBITSET_ELT_BITS - 1) / EBITSET_ELT_BITS
     : EBITSET_INITIAL_SIZE;
 
-  EBITSET_SIZE (bset) = 0;
+  EBITSET_ASIZE (bset) = 0;
   EBITSET_ELTS (bset) = 0;
-  ebitset_elts_grow (bset, size);
+  ebitset_resize (bset, n_bits);
 
   return bset;
 }
 
 
 void
-ebitset_release_memory ()
+ebitset_release_memory (void)
 {
   ebitset_free_list = 0;
   if (ebitset_obstack_init)
     {
-      ebitset_obstack_init = 0;
+      ebitset_obstack_init = false;
       obstack_free (&ebitset_obstack, NULL);
     }
 }