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, 17 insertions, 7 deletions

diff --git a/src/lisp.h b/src/lisp.h
index 2b197cd32b1..72e5dad8ca3 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -92,16 +92,16 @@ enum {  BOOL_VECTOR_BITS_PER_CHAR =
 /* An unsigned integer type representing a fixed-length bit sequence,
    suitable for words in a Lisp bool vector.  Normally it is size_t
    for speed, but it is unsigned char on weird platforms.  */
-#if (BITSIZEOF_SIZE_T == CHAR_BIT * SIZEOF_SIZE_T \
-     && BOOL_VECTOR_BITS_PER_CHAR == CHAR_BIT)
+#if BOOL_VECTOR_BITS_PER_CHAR == CHAR_BIT
 typedef size_t bits_word;
-#define BITS_WORD_MAX SIZE_MAX
+# define BITS_WORD_MAX SIZE_MAX
 enum { BITS_PER_BITS_WORD = CHAR_BIT * sizeof (bits_word) };
 #else
 typedef unsigned char bits_word;
-#define BITS_WORD_MAX ((1u << BOOL_VECTOR_BITS_PER_CHAR) - 1)
+# define BITS_WORD_MAX ((1u << BOOL_VECTOR_BITS_PER_CHAR) - 1)
 enum { BITS_PER_BITS_WORD = BOOL_VECTOR_BITS_PER_CHAR };
 #endif
+verify (BITS_WORD_MAX >> (BITS_PER_BITS_WORD - 1) == 1);
 
 /* Number of bits in some machine integer types.  */
 enum
@@ -1212,7 +1212,9 @@ struct Lisp_Bool_Vector
     struct vectorlike_header header;
     /* This is the size in bits.  */
     EMACS_INT size;
-    /* This contains the actual bits, packed into bytes.  */
+    /* The actual bits, packed into bytes.
+       The bits are in little-endian order in the bytes, and
+       the bytes are in little-endian order in the words.  */
     bits_word data[FLEXIBLE_ARRAY_MEMBER];
   };
 
@@ -1236,7 +1238,7 @@ bool_vector_uchar_data (Lisp_Object a)
   return (unsigned char *) bool_vector_data (a);
 }
 
-/* The number of data words in a bool vector with SIZE bits.  */
+/* The number of data words and bytes in a bool vector with SIZE bits.  */
 
 INLINE EMACS_INT
 bool_vector_words (EMACS_INT size)
@@ -1245,6 +1247,13 @@ bool_vector_words (EMACS_INT size)
   return (size + BITS_PER_BITS_WORD - 1) / BITS_PER_BITS_WORD;
 }
 
+INLINE EMACS_INT
+bool_vector_bytes (EMACS_INT size)
+{
+  eassume (0 <= size && size <= EMACS_INT_MAX - (BITS_PER_BITS_WORD - 1));
+  return (size + BOOL_VECTOR_BITS_PER_CHAR - 1) / BOOL_VECTOR_BITS_PER_CHAR;
+}
+
 /* True if A's Ith bit is set.  */
 
 INLINE bool
@@ -3588,7 +3597,8 @@ list4i (EMACS_INT x, EMACS_INT y, EMACS_INT w, EMACS_INT h)
                 make_number (w), make_number (h));
 }
 
-extern void bool_vector_fill (Lisp_Object, Lisp_Object);
+extern Lisp_Object make_uninit_bool_vector (EMACS_INT);
+extern Lisp_Object bool_vector_fill (Lisp_Object, Lisp_Object);
 extern _Noreturn void string_overflow (void);
 extern Lisp_Object make_string (const char *, ptrdiff_t);
 extern Lisp_Object make_formatted_string (char *, const char *, ...)