Copy regex BITSET_WORD_BITS porting from Gnulib

* posix/regex.c (__STDC_WANT_IEC_60559_BFP_EXT__):
Define, for ULONG_WIDTH.  This syncs regex.c from Gnujlib.
* posix/regex_internal.h (ULONG_WIDTH):
Use a more-portable fallback, from Gnulib.
(BITSET_WORD_BITS): Now defined in terms of ULONG_WIDTH.

2 files changed, 22 insertions, 30 deletions

diff --git a/posix/regex.c b/posix/regex.c
index 815e2ec..991eedc 100644
--- a/posix/regex.c
+++ b/posix/regex.c
@@ -17,6 +17,8 @@
    License along with the GNU C Library; if not, see
    <https://www.gnu.org/licenses/>.  */
 
+#define __STDC_WANT_IEC_60559_BFP_EXT__
+
 #ifndef _LIBC
 # include <libc-config.h>
 
diff --git a/posix/regex_internal.h b/posix/regex_internal.h
index 6f761c6..e9aa74b 100644
--- a/posix/regex_internal.h
+++ b/posix/regex_internal.h
@@ -141,6 +141,24 @@
 #ifndef SSIZE_MAX
 # define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
 #endif
+#ifndef ULONG_WIDTH
+# define ULONG_WIDTH REGEX_UINTEGER_WIDTH (ULONG_MAX)
+/* The number of usable bits in an unsigned integer type with maximum
+   value MAX, as an int expression suitable in #if.  Cover all known
+   practical hosts.  This implementation exploits the fact that MAX is
+   1 less than a power of 2, and merely counts the number of 1 bits in
+   MAX; "COBn" means "count the number of 1 bits in the low-order n bits".  */
+# define REGEX_UINTEGER_WIDTH(max) REGEX_COB128 (max)
+# define REGEX_COB128(n) (REGEX_COB64 ((n) >> 31 >> 31 >> 2) + REGEX_COB64 (n))
+# define REGEX_COB64(n) (REGEX_COB32 ((n) >> 31 >> 1) + REGEX_COB32 (n))
+# define REGEX_COB32(n) (REGEX_COB16 ((n) >> 16) + REGEX_COB16 (n))
+# define REGEX_COB16(n) (REGEX_COB8 ((n) >> 8) + REGEX_COB8 (n))
+# define REGEX_COB8(n) (REGEX_COB4 ((n) >> 4) + REGEX_COB4 (n))
+# define REGEX_COB4(n) (!!((n) & 8) + !!((n) & 4) + !!((n) & 2) + ((n) & 1))
+# if ULONG_MAX / 2 + 1 != 1ul << (ULONG_WIDTH - 1)
+#  error "ULONG_MAX out of range"
+# endif
+#endif
 
 /* The type of indexes into strings.  This is signed, not size_t,
    since the API requires indexes to fit in regoff_t anyway, and using
@@ -164,36 +182,8 @@ typedef __re_size_t re_hashval_t;
 typedef unsigned long int bitset_word_t;
 /* All bits set in a bitset_word_t.  */
 #define BITSET_WORD_MAX ULONG_MAX
-
-/* Number of bits in a bitset_word_t.  For portability to hosts with
-   padding bits, do not use '(sizeof (bitset_word_t) * CHAR_BIT)';
-   instead, deduce it directly from BITSET_WORD_MAX.  Avoid
-   greater-than-32-bit integers and unconditional shifts by more than
-   31 bits, as they're not portable.  */
-#if BITSET_WORD_MAX == 0xffffffffUL
-# define BITSET_WORD_BITS 32
-#elif BITSET_WORD_MAX >> 31 >> 4 == 1
-# define BITSET_WORD_BITS 36
-#elif BITSET_WORD_MAX >> 31 >> 16 == 1
-# define BITSET_WORD_BITS 48
-#elif BITSET_WORD_MAX >> 31 >> 28 == 1
-# define BITSET_WORD_BITS 60
-#elif BITSET_WORD_MAX >> 31 >> 31 >> 1 == 1
-# define BITSET_WORD_BITS 64
-#elif BITSET_WORD_MAX >> 31 >> 31 >> 9 == 1
-# define BITSET_WORD_BITS 72
-#elif BITSET_WORD_MAX >> 31 >> 31 >> 31 >> 31 >> 3 == 1
-# define BITSET_WORD_BITS 128
-#elif BITSET_WORD_MAX >> 31 >> 31 >> 31 >> 31 >> 31 >> 31 >> 31 >> 31 >> 7 == 1
-# define BITSET_WORD_BITS 256
-#elif BITSET_WORD_MAX >> 31 >> 31 >> 31 >> 31 >> 31 >> 31 >> 31 >> 31 >> 7 > 1
-# define BITSET_WORD_BITS 257 /* any value > SBC_MAX will do here */
-# if BITSET_WORD_BITS <= SBC_MAX
-#  error "Invalid SBC_MAX"
-# endif
-#else
-# error "Add case for new bitset_word_t size"
-#endif
+/* Number of bits in a bitset_word_t.  */
+#define BITSET_WORD_BITS ULONG_WIDTH
 
 /* Number of bitset_word_t values in a bitset_t.  */
 #define BITSET_WORDS ((SBC_MAX + BITSET_WORD_BITS - 1) / BITSET_WORD_BITS)