Simplify, port and tune bool vector implementation.

* configure.ac (BITSIZEOF_SIZE_T, SIZEOF_SIZE_T): Remove.
* src/alloc.c (bool_vector_exact_payload_bytes)
(bool_vector_payload_bytes): Remove.
(bool_vector_fill): Return its argument.
* src/alloc.c (bool_vector_fill):
* src/lread.c (read1):
* src/print.c (print_object):
Simplify by using bool_vector_bytes.
* src/alloc.c (make_uninit_bool_vector):
New function, broken out from Fmake_bool_vector.
(Fmake_bool_vector): Use it.  Use tail call.
(make_uninit_bool_vector, vector_nbytes): Simplify size calculations.
* src/data.c (BITS_PER_ULL): New constant.
(ULLONG_MAX, count_one_bits_ll): Fall back on long counterparts
if long long versions don't exist.
(shift_right_ull): New function.
(count_one_bits_word): New function, replacing popcount_bits_word
macro.  Don't assume that bits_word is no wider than long long.
(count_one_bits_word, count_trailing_zero_bits):
Don't assume that bits_word is no wider than long long.
* src/data.c (bool_vector_binop_driver, bool_vector_not):
* src/fns.c (Fcopy_sequence):
* src/lread.c (read1):
Create an uninitialized destination, to avoid needless work.
(internal_equal): Simplify.
(Ffillarray): Prefer tail call.
* src/data.c (bool_vector_binop_driver): Don't assume bit vectors always
contain at least one word.
(bits_word_to_host_endian): Prefer if to #if.  Don't assume
chars are narrower than ints.
* src/data.c (Fbool_vector_count_matches, Fbool_vector_count_matches_at):
* src/fns.c (Fcopy_sequence):
Simplify and tune.
* src/lisp.h (bits_word, BITS_WORD_MAX, BITS_PER_BITS_WORD):
Don't try to port to hosts where bits_word values have holes; the
code wouldn't work there anyway.  Verify this assumption, though.
(bool_vector_bytes): New function.
(make_uninit_bool_vector): New decl.
(bool_vector_fill): Now returns Lisp_Object.

1 files changed, 92 insertions, 63 deletions

diff --git a/src/data.c b/src/data.c
index 4043fbe279b..7ff7ac6b130 100644
--- a/src/data.c
+++ b/src/data.c
@@ -2962,9 +2962,7 @@ lowercase l) for small endian machines.  */)
 
 /* Because we round up the bool vector allocate size to word_size
    units, we can safely read past the "end" of the vector in the
-   operations below.  These extra bits are always zero.  Also, we
-   always allocate bool vectors with at least one bits_word of storage so
-   that we don't have to special-case empty bit vectors.  */
+   operations below.  These extra bits are always zero.  */
 
 static bits_word
 bool_vector_spare_mask (EMACS_INT nr_bits)
@@ -2972,16 +2970,47 @@ bool_vector_spare_mask (EMACS_INT nr_bits)
   return (((bits_word) 1) << (nr_bits % BITS_PER_BITS_WORD)) - 1;
 }
 
-#if BITS_WORD_MAX <= UINT_MAX
-# define popcount_bits_word count_one_bits
-#elif BITS_WORD_MAX <= ULONG_MAX
-# define popcount_bits_word count_one_bits_l
-#elif BITS_WORD_MAX <= ULLONG_MAX
-# define popcount_bits_word count_one_bits_ll
+/* Info about unsigned long long, falling back on unsigned long
+   if unsigned long long is not available.  */
+
+#if HAVE_UNSIGNED_LONG_LONG_INT
+enum { BITS_PER_ULL = CHAR_BIT * sizeof (unsigned long long) };
 #else
-# error "bits_word wider than long long? Please file a bug report."
+enum { BITS_PER_ULL = CHAR_BIT * sizeof (unsigned long) };
+# define ULLONG_MAX ULONG_MAX
+# define count_one_bits_ll count_one_bits_l
 #endif
 
+/* Shift VAL right by the width of an unsigned long long.
+   BITS_PER_ULL must be less than BITS_PER_BITS_WORD.  */
+
+static bits_word
+shift_right_ull (bits_word w)
+{
+  /* Pacify bogus GCC warning about shift count exceeding type width.  */
+  int shift = BITS_PER_ULL - BITS_PER_BITS_WORD < 0 ? BITS_PER_ULL : 0;
+  return w >> shift;
+}
+
+/* Return the number of 1 bits in W.  */
+
+static int
+count_one_bits_word (bits_word w)
+{
+  if (BITS_WORD_MAX <= UINT_MAX)
+    return count_one_bits (w);
+  else if (BITS_WORD_MAX <= ULONG_MAX)
+    return count_one_bits_l (w);
+  else
+    {
+      int i = 0, count = 0;
+      while (count += count_one_bits_ll (w),
+             BITS_PER_BITS_WORD <= (i += BITS_PER_ULL))
+        w = shift_right_ull (w);
+      return count;
+    }
+}
+
 enum bool_vector_op { bool_vector_exclusive_or,
                       bool_vector_union,
                       bool_vector_intersection,
@@ -2997,7 +3026,7 @@ bool_vector_binop_driver (Lisp_Object op1,
   EMACS_INT nr_bits;
   bits_word *adata, *bdata, *cdata;
   ptrdiff_t i;
-  bits_word changed = 0;
+  bool changed = 0;
   bits_word mword;
   ptrdiff_t nr_words;
 
@@ -3010,7 +3039,7 @@ bool_vector_binop_driver (Lisp_Object op1,
 
   if (NILP (dest))
     {
-      dest = Fmake_bool_vector (make_number (nr_bits), Qnil);
+      dest = make_uninit_bool_vector (nr_bits);
       changed = 1;
     }
   else
@@ -3025,8 +3054,8 @@ bool_vector_binop_driver (Lisp_Object op1,
   adata = bool_vector_data (dest);
   bdata = bool_vector_data (op1);
   cdata = bool_vector_data (op2);
-  i = 0;
-  do
+
+  for (i = 0; i < nr_words; i++)
     {
       if (op == bool_vector_exclusive_or)
         mword = bdata[i] ^ cdata[i];
@@ -3039,14 +3068,12 @@ bool_vector_binop_driver (Lisp_Object op1,
       else
         abort ();
 
-      changed |= adata[i] ^ mword;
+      if (! changed)
+        changed = adata[i] != mword;
 
       if (op != bool_vector_subsetp)
         adata[i] = mword;
-
-      i++;
     }
-  while (i < nr_words);
 
   return changed ? dest : Qnil;
 }
@@ -3060,27 +3087,33 @@ count_trailing_zero_bits (bits_word val)
     return count_trailing_zeros (val);
   if (BITS_WORD_MAX == ULONG_MAX)
     return count_trailing_zeros_l (val);
-# if HAVE_UNSIGNED_LONG_LONG_INT
   if (BITS_WORD_MAX == ULLONG_MAX)
     return count_trailing_zeros_ll (val);
-# endif
 
   /* The rest of this code is for the unlikely platform where bits_word differs
      in width from unsigned int, unsigned long, and unsigned long long.  */
-  if (val == 0)
-    return CHAR_BIT * sizeof (val);
+  val |= ~ BITS_WORD_MAX;
   if (BITS_WORD_MAX <= UINT_MAX)
     return count_trailing_zeros (val);
   if (BITS_WORD_MAX <= ULONG_MAX)
     return count_trailing_zeros_l (val);
-  {
-# if HAVE_UNSIGNED_LONG_LONG_INT
-    verify (BITS_WORD_MAX <= ULLONG_MAX);
-    return count_trailing_zeros_ll (val);
-# else
-    verify (BITS_WORD_MAX <= ULONG_MAX);
-# endif
-  }
+  else
+    {
+      int count;
+      for (count = 0;
+           count < BITS_PER_BITS_WORD - BITS_PER_ULL;
+           count += BITS_PER_ULL)
+        {
+          if (val & ULLONG_MAX)
+            return count + count_trailing_zeros_ll (val);
+          val = shift_right_ull (val);
+        }
+
+      if (BITS_PER_BITS_WORD % BITS_PER_ULL != 0
+          && BITS_WORD_MAX == (bits_word) -1)
+        val |= (bits_word) 1 << (BITS_PER_BITS_WORD % BITS_PER_ULL);
+      return count + count_trailing_zeros_ll (val);
+    }
 }
 
 static bits_word
@@ -3088,20 +3121,24 @@ bits_word_to_host_endian (bits_word val)
 {
 #ifndef WORDS_BIGENDIAN
   return val;
-#elif BITS_WORD_MAX >> 31 == 1
-  return bswap_32 (val);
-#elif BITS_WORD_MAX >> 31 >> 31 >> 1 == 1
-  return bswap_64 (val);
 #else
-  int i;
-  bits_word r = 0;
-  for (i = 0; i < sizeof val; i++)
-    {
-      r = ((r << 1 << (CHAR_BIT - 1))
-           | (val & ((1u << 1 << (CHAR_BIT - 1)) - 1)));
-      val = val >> 1 >> (CHAR_BIT - 1);
-    }
-  return r;
+  if (BITS_WORD_MAX >> 31 == 1)
+    return bswap_32 (val);
+# if HAVE_UNSIGNED_LONG_LONG
+  if (BITS_WORD_MAX >> 31 >> 31 >> 1 == 1)
+    return bswap_64 (val);
+# endif
+  {
+    int i;
+    bits_word r = 0;
+    for (i = 0; i < sizeof val; i++)
+      {
+        r = ((r << 1 << (CHAR_BIT - 1))
+             | (val & ((1u << 1 << (CHAR_BIT - 1)) - 1)));
+        val = val >> 1 >> (CHAR_BIT - 1);
+      }
+    return r;
+  }
 #endif
 }
 
@@ -3174,7 +3211,7 @@ Return the destination vector.  */)
   nr_bits = bool_vector_size (a);
 
   if (NILP (b))
-    b = Fmake_bool_vector (make_number (nr_bits), Qnil);
+    b = make_uninit_bool_vector (nr_bits);
   else
     {
       CHECK_BOOL_VECTOR (b);
@@ -3208,27 +3245,20 @@ A must be a bool vector.  B is a generalized bool.  */)
   EMACS_INT count;
   EMACS_INT nr_bits;
   bits_word *adata;
-  bits_word match;
-  ptrdiff_t i;
+  ptrdiff_t i, nwords;
 
   CHECK_BOOL_VECTOR (a);
 
   nr_bits = bool_vector_size (a);
+  nwords = bool_vector_words (nr_bits);
   count = 0;
-  match = NILP (b) ? BITS_WORD_MAX : 0;
   adata = bool_vector_data (a);
 
-  for (i = 0; i < nr_bits / BITS_PER_BITS_WORD; ++i)
-    count += popcount_bits_word (adata[i] ^ match);
-
-  /* Mask out trailing parts of final mword.  */
-  if (nr_bits % BITS_PER_BITS_WORD)
-    {
-      bits_word mword = adata[i] ^ match;
-      mword = bits_word_to_host_endian (mword);
-      count += popcount_bits_word (mword & bool_vector_spare_mask (nr_bits));
-    }
+  for (i = 0; i < nwords; i++)
+    count += count_one_bits_word (adata[i]);
 
+  if (NILP (b))
+    count = nr_bits - count;
   return make_number (count);
 }
 
@@ -3246,7 +3276,7 @@ index into the vector.  */)
   bits_word *adata;
   bits_word twiddle;
   bits_word mword; /* Machine word.  */
-  ptrdiff_t pos;
+  ptrdiff_t pos, pos0;
   ptrdiff_t nr_words;
 
   CHECK_BOOL_VECTOR (a);
@@ -3273,8 +3303,8 @@ index into the vector.  */)
       mword = bits_word_to_host_endian (adata[pos]);
       mword ^= twiddle;
       mword >>= offset;
+      mword |= (bits_word) 1 << (BITS_PER_BITS_WORD - offset);
       count = count_trailing_zero_bits (mword);
-      count = min (count, BITS_PER_BITS_WORD - offset);
       pos++;
       if (count + offset < BITS_PER_BITS_WORD)
         return make_number (count);
@@ -3283,11 +3313,10 @@ index into the vector.  */)
   /* Scan whole words until we either reach the end of the vector or
      find an mword that doesn't completely match.  twiddle is
      endian-independent.  */
+  pos0 = pos;
   while (pos < nr_words && adata[pos] == twiddle)
-    {
-      count += BITS_PER_BITS_WORD;
-      ++pos;
-    }
+    pos++;
+  count += (pos - pos0) * BITS_PER_BITS_WORD;
 
   if (pos < nr_words)
     {