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authorAdhemerval Zanella <adhemerval.zanella@linaro.org>2016-03-26 19:09:07 +0000
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2016-04-01 10:44:44 -0300
commit91f3b75f47c9eca3299098c3dcc2f5d9dad320b1 (patch)
treef00e3a58386999ac44a322211ff74cffcb37df99 /string
parentd3496c9f4f27d3009b71be87f6108b4fed7314bd (diff)
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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.
Diffstat (limited to 'string')
-rw-r--r--string/bits/string2.h74
-rw-r--r--string/string-inlines.c36
-rw-r--r--string/strspn.c57
3 files changed, 81 insertions, 86 deletions
diff --git a/string/bits/string2.h b/string/bits/string2.h
index a8df0db..75a66a1 100644
--- a/string/bits/string2.h
+++ b/string/bits/string2.h
@@ -914,78 +914,10 @@ __stpcpy_small (char *__dest,
/* Return the length of the initial segment of S which
consists entirely of characters in ACCEPT. */
-#if !defined _HAVE_STRING_ARCH_strspn || defined _FORCE_INLINES
-# ifndef _HAVE_STRING_ARCH_strspn
-# if __GNUC_PREREQ (3, 2)
-# define strspn(s, accept) \
- __extension__ \
- ({ char __a0, __a1, __a2; \
- (__builtin_constant_p (accept) && __string2_1bptr_p (accept) \
- ? ((__builtin_constant_p (s) && __string2_1bptr_p (s)) \
- ? __builtin_strspn (s, accept) \
- : ((__a0 = ((const char *) (accept))[0], __a0 == '\0') \
- ? ((void) (s), (size_t) 0) \
- : ((__a1 = ((const char *) (accept))[1], __a1 == '\0') \
- ? __strspn_c1 (s, __a0) \
- : ((__a2 = ((const char *) (accept))[2], __a2 == '\0') \
- ? __strspn_c2 (s, __a0, __a1) \
- : (((const char *) (accept))[3] == '\0' \
- ? __strspn_c3 (s, __a0, __a1, __a2) \
- : __builtin_strspn (s, accept)))))) \
- : __builtin_strspn (s, accept)); })
-# else
-# define strspn(s, accept) \
- __extension__ \
- ({ char __a0, __a1, __a2; \
- (__builtin_constant_p (accept) && __string2_1bptr_p (accept) \
- ? ((__a0 = ((const char *) (accept))[0], __a0 == '\0') \
- ? ((void) (s), (size_t) 0) \
- : ((__a1 = ((const char *) (accept))[1], __a1 == '\0') \
- ? __strspn_c1 (s, __a0) \
- : ((__a2 = ((const char *) (accept))[2], __a2 == '\0') \
- ? __strspn_c2 (s, __a0, __a1) \
- : (((const char *) (accept))[3] == '\0' \
- ? __strspn_c3 (s, __a0, __a1, __a2) \
- : strspn (s, accept))))) \
- : strspn (s, accept)); })
-# endif
+#ifndef _HAVE_STRING_ARCH_strspn
+# if __GNUC_PREREQ (3, 2)
+# define strspn(s, accept) __builtin_strspn (s, accept)
# endif
-
-__STRING_INLINE size_t __strspn_c1 (const char *__s, int __accept);
-__STRING_INLINE size_t
-__strspn_c1 (const char *__s, int __accept)
-{
- size_t __result = 0;
- /* Please note that __accept never can be '\0'. */
- while (__s[__result] == __accept)
- ++__result;
- return __result;
-}
-
-__STRING_INLINE size_t __strspn_c2 (const char *__s, int __accept1,
- int __accept2);
-__STRING_INLINE size_t
-__strspn_c2 (const char *__s, int __accept1, int __accept2)
-{
- size_t __result = 0;
- /* Please note that __accept1 and __accept2 never can be '\0'. */
- while (__s[__result] == __accept1 || __s[__result] == __accept2)
- ++__result;
- return __result;
-}
-
-__STRING_INLINE size_t __strspn_c3 (const char *__s, int __accept1,
- int __accept2, int __accept3);
-__STRING_INLINE size_t
-__strspn_c3 (const char *__s, int __accept1, int __accept2, int __accept3)
-{
- size_t __result = 0;
- /* Please note that __accept1 to __accept3 never can be '\0'. */
- while (__s[__result] == __accept1 || __s[__result] == __accept2
- || __s[__result] == __accept3)
- ++__result;
- return __result;
-}
#endif
diff --git a/string/string-inlines.c b/string/string-inlines.c
index 83bdd6c..754b315 100644
--- a/string/string-inlines.c
+++ b/string/string-inlines.c
@@ -71,4 +71,40 @@ __old_strcspn_c3 (const char *__s, int __reject1, int __reject2,
return __result;
}
compat_symbol (libc, __old_strcspn_c3, __strcspn_c3, GLIBC_2_1_1);
+
+size_t
+__old_strspn_c1 (const char *__s, int __accept)
+{
+ size_t __result = 0;
+ /* Please note that __accept never can be '\0'. */
+ while (__s[__result] == __accept)
+ ++__result;
+ return __result;
+}
+compat_symbol (libc, __old_strspn_c1, __strspn_c1, GLIBC_2_1_1);
+
+size_t
+__old_strspn_c2 (const char *__s, int __accept1, int __accept2)
+{
+ size_t __result = 0;
+ /* Please note that __accept1 and __accept2 never can be '\0'. */
+ while (__s[__result] == __accept1 || __s[__result] == __accept2)
+ ++__result;
+ return __result;
+}
+compat_symbol (libc, __old_strspn_c2, __strspn_c2, GLIBC_2_1_1);
+
+size_t
+__old_strspn_c3 (const char *__s, int __accept1, int __accept2,
+ int __accept3)
+{
+ size_t __result = 0;
+ /* Please note that __accept1 to __accept3 never can be '\0'. */
+ while (__s[__result] == __accept1 || __s[__result] == __accept2
+ || __s[__result] == __accept3)
+ ++__result;
+ return __result;
+}
+compat_symbol (libc, __old_strspn_c3, __strspn_c3, GLIBC_2_1_1);
+
#endif
diff --git a/string/strspn.c b/string/strspn.c
index f0635c1..f98340b 100644
--- a/string/strspn.c
+++ b/string/strspn.c
@@ -16,32 +16,59 @@
<http://www.gnu.org/licenses/>. */
#include <string.h>
+#include <stdint.h>
#undef strspn
#ifndef STRSPN
-#define STRSPN strspn
+# define STRSPN strspn
#endif
/* Return the length of the maximum initial segment
of S which contains only characters in ACCEPT. */
size_t
-STRSPN (const char *s, const char *accept)
+STRSPN (const char *str, const char *accept)
{
- const char *p;
- const char *a;
- size_t count = 0;
-
- for (p = s; *p != '\0'; ++p)
+ if (accept[0] == '\0')
+ return 0;
+ if (__glibc_unlikely (accept[1] == '\0'))
{
- for (a = accept; *a != '\0'; ++a)
- if (*p == *a)
- break;
- if (*a == '\0')
- return count;
- else
- ++count;
+ const char *a = str;
+ for (; *str == *accept; str++);
+ return str - a;
}
- return count;
+ /* Use multiple small memsets to enable inlining on most targets. */
+ unsigned char table[256];
+ unsigned char *p = memset (table, 0, 64);
+ memset (p + 64, 0, 64);
+ memset (p + 128, 0, 64);
+ memset (p + 192, 0, 64);
+
+ unsigned char *s = (unsigned char*) accept;
+ /* Different from strcspn it does not add the NULL on the table
+ so can avoid check if str[i] is NULL, since table['\0'] will
+ be 0 and thus stopping the loop check. */
+ do
+ p[*s++] = 1;
+ while (*s);
+
+ s = (unsigned char*) str;
+ if (!p[s[0]]) return 0;
+ if (!p[s[1]]) return 1;
+ if (!p[s[2]]) return 2;
+ if (!p[s[3]]) return 3;
+
+ s = (unsigned char *) ((uintptr_t)(s) & ~3);
+ unsigned int c0, c1, c2, c3;
+ do {
+ s += 4;
+ c0 = p[s[0]];
+ c1 = p[s[1]];
+ c2 = p[s[2]];
+ c3 = p[s[3]];
+ } while ((c0 & c1 & c2 & c3) != 0);
+
+ size_t count = s - (unsigned char *) str;
+ return (c0 & c1) == 0 ? count + c0 : count + c2 + 2;
}
libc_hidden_builtin_def (strspn)