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Improve generic strspn performance
As for strcspn, this patch improves strspn performance using a much faster algorithm. It first constructs a 256-entry table based on the accept string and then uses it as a lookup table for the input string. As for strcspn optimization, it is generally at least 10 times faster than the existing implementation on bench-strspn on a few AArch64 implementations. Also the string/bits/string2.h inlines make no longer sense, as current implementation will already implement most of the optimizations. Tested on x86_64, i686, and aarch64. * string/strspn.c (strcspn): Rewrite function. * string/bits/string2.h (strspn): Use __builtin_strcspn. (__strspn_c1): Remove inline function. (__strspn_c2): Likewise. (__strspn_c3): Likewise. * string/string-inlines.c [SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strspn_c1): Add compatibility symbol. [SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strspn_c2): Likewise. [SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strspn_c3): Likewise.
This commit is contained in:
Adhemerval Zanella
parent
d3496c9f4f
commit
91f3b75f47
16
ChangeLog
16
ChangeLog
@ -1,3 +1,19 @@
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2016-04-01 Adhemerval Zanella <adhemerval.zanella@linaro.org>
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* string/strspn.c (strcspn): Rewrite function.
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* string/bits/string2.h (strspn): Use __builtin_strcspn.
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(__strspn_c1): Remove inline function.
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(__strspn_c2): Likewise.
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(__strspn_c3): Likewise.
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* string/string-inlines.c
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[SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strspn_c1): Add
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compatibility symbol.
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[SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strspn_c2):
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Likewise.
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[SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strspn_c3):
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Likewise.
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* string/string-inlines.c: Include generic version.
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2016-04-01 Wilco Dijkstra <wdijkstr@arm.com>
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Adhemerval Zanella <adhemerval.zanella@linaro.org>
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@ -914,78 +914,10 @@ __stpcpy_small (char *__dest,
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/* Return the length of the initial segment of S which
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consists entirely of characters in ACCEPT. */
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#if !defined _HAVE_STRING_ARCH_strspn || defined _FORCE_INLINES
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# ifndef _HAVE_STRING_ARCH_strspn
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# if __GNUC_PREREQ (3, 2)
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# define strspn(s, accept) \
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__extension__ \
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({ char __a0, __a1, __a2; \
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(__builtin_constant_p (accept) && __string2_1bptr_p (accept) \
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? ((__builtin_constant_p (s) && __string2_1bptr_p (s)) \
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? __builtin_strspn (s, accept) \
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: ((__a0 = ((const char *) (accept))[0], __a0 == '\0') \
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? ((void) (s), (size_t) 0) \
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: ((__a1 = ((const char *) (accept))[1], __a1 == '\0') \
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? __strspn_c1 (s, __a0) \
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: ((__a2 = ((const char *) (accept))[2], __a2 == '\0') \
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? __strspn_c2 (s, __a0, __a1) \
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: (((const char *) (accept))[3] == '\0' \
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? __strspn_c3 (s, __a0, __a1, __a2) \
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: __builtin_strspn (s, accept)))))) \
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: __builtin_strspn (s, accept)); })
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# else
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# define strspn(s, accept) \
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__extension__ \
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({ char __a0, __a1, __a2; \
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(__builtin_constant_p (accept) && __string2_1bptr_p (accept) \
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? ((__a0 = ((const char *) (accept))[0], __a0 == '\0') \
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? ((void) (s), (size_t) 0) \
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: ((__a1 = ((const char *) (accept))[1], __a1 == '\0') \
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? __strspn_c1 (s, __a0) \
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: ((__a2 = ((const char *) (accept))[2], __a2 == '\0') \
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? __strspn_c2 (s, __a0, __a1) \
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: (((const char *) (accept))[3] == '\0' \
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? __strspn_c3 (s, __a0, __a1, __a2) \
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: strspn (s, accept))))) \
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: strspn (s, accept)); })
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# endif
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#ifndef _HAVE_STRING_ARCH_strspn
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# if __GNUC_PREREQ (3, 2)
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# define strspn(s, accept) __builtin_strspn (s, accept)
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# endif
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__STRING_INLINE size_t __strspn_c1 (const char *__s, int __accept);
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__STRING_INLINE size_t
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__strspn_c1 (const char *__s, int __accept)
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{
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size_t __result = 0;
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/* Please note that __accept never can be '\0'. */
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while (__s[__result] == __accept)
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++__result;
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return __result;
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}
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__STRING_INLINE size_t __strspn_c2 (const char *__s, int __accept1,
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int __accept2);
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__STRING_INLINE size_t
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__strspn_c2 (const char *__s, int __accept1, int __accept2)
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{
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size_t __result = 0;
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/* Please note that __accept1 and __accept2 never can be '\0'. */
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while (__s[__result] == __accept1 || __s[__result] == __accept2)
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++__result;
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return __result;
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}
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__STRING_INLINE size_t __strspn_c3 (const char *__s, int __accept1,
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int __accept2, int __accept3);
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__STRING_INLINE size_t
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__strspn_c3 (const char *__s, int __accept1, int __accept2, int __accept3)
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{
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size_t __result = 0;
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/* Please note that __accept1 to __accept3 never can be '\0'. */
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while (__s[__result] == __accept1 || __s[__result] == __accept2
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|| __s[__result] == __accept3)
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++__result;
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return __result;
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}
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#endif
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@ -71,4 +71,40 @@ __old_strcspn_c3 (const char *__s, int __reject1, int __reject2,
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return __result;
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}
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compat_symbol (libc, __old_strcspn_c3, __strcspn_c3, GLIBC_2_1_1);
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size_t
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__old_strspn_c1 (const char *__s, int __accept)
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{
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size_t __result = 0;
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/* Please note that __accept never can be '\0'. */
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while (__s[__result] == __accept)
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++__result;
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return __result;
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}
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compat_symbol (libc, __old_strspn_c1, __strspn_c1, GLIBC_2_1_1);
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size_t
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__old_strspn_c2 (const char *__s, int __accept1, int __accept2)
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{
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size_t __result = 0;
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/* Please note that __accept1 and __accept2 never can be '\0'. */
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while (__s[__result] == __accept1 || __s[__result] == __accept2)
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++__result;
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return __result;
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}
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compat_symbol (libc, __old_strspn_c2, __strspn_c2, GLIBC_2_1_1);
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size_t
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__old_strspn_c3 (const char *__s, int __accept1, int __accept2,
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int __accept3)
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{
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size_t __result = 0;
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/* Please note that __accept1 to __accept3 never can be '\0'. */
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while (__s[__result] == __accept1 || __s[__result] == __accept2
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|| __s[__result] == __accept3)
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++__result;
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return __result;
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}
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compat_symbol (libc, __old_strspn_c3, __strspn_c3, GLIBC_2_1_1);
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#endif
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@ -16,32 +16,59 @@
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<http://www.gnu.org/licenses/>. */
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#include <string.h>
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#include <stdint.h>
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#undef strspn
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#ifndef STRSPN
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#define STRSPN strspn
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# define STRSPN strspn
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#endif
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/* Return the length of the maximum initial segment
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of S which contains only characters in ACCEPT. */
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size_t
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STRSPN (const char *s, const char *accept)
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STRSPN (const char *str, const char *accept)
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{
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const char *p;
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const char *a;
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size_t count = 0;
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for (p = s; *p != '\0'; ++p)
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if (accept[0] == '\0')
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return 0;
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if (__glibc_unlikely (accept[1] == '\0'))
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{
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for (a = accept; *a != '\0'; ++a)
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if (*p == *a)
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break;
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if (*a == '\0')
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return count;
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else
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++count;
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const char *a = str;
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for (; *str == *accept; str++);
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return str - a;
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}
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return count;
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/* Use multiple small memsets to enable inlining on most targets. */
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unsigned char table[256];
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unsigned char *p = memset (table, 0, 64);
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memset (p + 64, 0, 64);
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memset (p + 128, 0, 64);
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memset (p + 192, 0, 64);
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unsigned char *s = (unsigned char*) accept;
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/* Different from strcspn it does not add the NULL on the table
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so can avoid check if str[i] is NULL, since table['\0'] will
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be 0 and thus stopping the loop check. */
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do
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p[*s++] = 1;
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while (*s);
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s = (unsigned char*) str;
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if (!p[s[0]]) return 0;
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if (!p[s[1]]) return 1;
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if (!p[s[2]]) return 2;
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if (!p[s[3]]) return 3;
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s = (unsigned char *) ((uintptr_t)(s) & ~3);
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unsigned int c0, c1, c2, c3;
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do {
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s += 4;
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c0 = p[s[0]];
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c1 = p[s[1]];
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c2 = p[s[2]];
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c3 = p[s[3]];
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} while ((c0 & c1 & c2 & c3) != 0);
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size_t count = s - (unsigned char *) str;
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return (c0 & c1) == 0 ? count + c0 : count + c2 + 2;
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}
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libc_hidden_builtin_def (strspn)
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