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authorWilco Dijkstra <wdijkstr@arm.com>2016-03-25 16:44:26 -0300
committerAdhemerval Zanella <adhemerval.zanella@linaro.org>2016-04-01 10:44:40 -0300
commitd3496c9f4f27d3009b71be87f6108b4fed7314bd (patch)
treeeefcd05beb1f6ed269167433a763c234483b7c0b /string
parentd8a012c5c9e4bfc1b8db2bc6deacb85b44a2e1eb (diff)
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Improve generic strcspn performance
Improve strcspn performance using a much faster algorithm. It is kept simple so it works well on most targets. It is generally at least 10 times faster than the existing implementation on bench-strcspn on a few AArch64 implementations, and for some tests 100 times as fast (repeatedly calling strchr on a small string is extremely slow...). In fact the string/bits/string2.h inlines make no longer sense, as GCC already uses strlen if reject is an empty string, strchrnul is 5 times as fast as __strcspn_c1, while __strcspn_c2 and __strcspn_c3 are slower than the strcspn main loop for large strings (though reject length 2-4 could be special cased in the future to gain even more performance). Tested on x86_64, i686, and aarch64. * string/Version (libc): Add GLIBC_2.24. * string/strcspn.c (strcspn): Rewrite function. * string/bits/string2.h (strcspn): Use __builtin_strcspn. (__strcspn_c1): Remove inline function. (__strcspn_c2): Likewise. (__strcspn_c3): Likewise. * string/string-inline.c [SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strcspn_c1): Add compatibility symbol. [SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strcspn_c2): Likewise. [SHLIB_COMPAT(libc, GLIBC_2_1_1, GLIBC_2_24)] (__strcspn_c3): Likewise. * sysdeps/i386/string-inlines.c: Include generic string-inlines.c.
Diffstat (limited to 'string')
-rw-r--r--string/Versions2
-rw-r--r--string/bits/string2.h73
-rw-r--r--string/strcspn.c46
-rw-r--r--string/string-inlines.c40
4 files changed, 83 insertions, 78 deletions
diff --git a/string/Versions b/string/Versions
index 59bf35a..475c1fd 100644
--- a/string/Versions
+++ b/string/Versions
@@ -80,4 +80,6 @@ libc {
GLIBC_2.6 {
strerror_l;
}
+ GLIBC_2.24 {
+ }
}
diff --git a/string/bits/string2.h b/string/bits/string2.h
index 8200ef1..a8df0db 100644
--- a/string/bits/string2.h
+++ b/string/bits/string2.h
@@ -905,77 +905,10 @@ __stpcpy_small (char *__dest,
/* Return the length of the initial segment of S which
consists entirely of characters not in REJECT. */
-#if !defined _HAVE_STRING_ARCH_strcspn || defined _FORCE_INLINES
-# ifndef _HAVE_STRING_ARCH_strcspn
-# if __GNUC_PREREQ (3, 2)
-# define strcspn(s, reject) \
- __extension__ \
- ({ char __r0, __r1, __r2; \
- (__builtin_constant_p (reject) && __string2_1bptr_p (reject) \
- ? ((__builtin_constant_p (s) && __string2_1bptr_p (s)) \
- ? __builtin_strcspn (s, reject) \
- : ((__r0 = ((const char *) (reject))[0], __r0 == '\0') \
- ? strlen (s) \
- : ((__r1 = ((const char *) (reject))[1], __r1 == '\0') \
- ? __strcspn_c1 (s, __r0) \
- : ((__r2 = ((const char *) (reject))[2], __r2 == '\0') \
- ? __strcspn_c2 (s, __r0, __r1) \
- : (((const char *) (reject))[3] == '\0' \
- ? __strcspn_c3 (s, __r0, __r1, __r2) \
- : __builtin_strcspn (s, reject)))))) \
- : __builtin_strcspn (s, reject)); })
-# else
-# define strcspn(s, reject) \
- __extension__ \
- ({ char __r0, __r1, __r2; \
- (__builtin_constant_p (reject) && __string2_1bptr_p (reject) \
- ? ((__r0 = ((const char *) (reject))[0], __r0 == '\0') \
- ? strlen (s) \
- : ((__r1 = ((const char *) (reject))[1], __r1 == '\0') \
- ? __strcspn_c1 (s, __r0) \
- : ((__r2 = ((const char *) (reject))[2], __r2 == '\0') \
- ? __strcspn_c2 (s, __r0, __r1) \
- : (((const char *) (reject))[3] == '\0' \
- ? __strcspn_c3 (s, __r0, __r1, __r2) \
- : strcspn (s, reject))))) \
- : strcspn (s, reject)); })
-# endif
+#ifndef _HAVE_STRING_ARCH_strcspn
+# if __GNUC_PREREQ (3, 2)
+# define strcspn(s, reject) __builtin_strcspn (s, reject)
# endif
-
-__STRING_INLINE size_t __strcspn_c1 (const char *__s, int __reject);
-__STRING_INLINE size_t
-__strcspn_c1 (const char *__s, int __reject)
-{
- size_t __result = 0;
- while (__s[__result] != '\0' && __s[__result] != __reject)
- ++__result;
- return __result;
-}
-
-__STRING_INLINE size_t __strcspn_c2 (const char *__s, int __reject1,
- int __reject2);
-__STRING_INLINE size_t
-__strcspn_c2 (const char *__s, int __reject1, int __reject2)
-{
- size_t __result = 0;
- while (__s[__result] != '\0' && __s[__result] != __reject1
- && __s[__result] != __reject2)
- ++__result;
- return __result;
-}
-
-__STRING_INLINE size_t __strcspn_c3 (const char *__s, int __reject1,
- int __reject2, int __reject3);
-__STRING_INLINE size_t
-__strcspn_c3 (const char *__s, int __reject1, int __reject2,
- int __reject3)
-{
- size_t __result = 0;
- while (__s[__result] != '\0' && __s[__result] != __reject1
- && __s[__result] != __reject2 && __s[__result] != __reject3)
- ++__result;
- return __result;
-}
#endif
diff --git a/string/strcspn.c b/string/strcspn.c
index 8888919..c535dd1 100644
--- a/string/strcspn.c
+++ b/string/strcspn.c
@@ -16,6 +16,7 @@
<http://www.gnu.org/licenses/>. */
#include <string.h>
+#include <stdint.h>
#undef strcspn
@@ -26,16 +27,45 @@
/* Return the length of the maximum initial segment of S
which contains no characters from REJECT. */
size_t
-STRCSPN (const char *s, const char *reject)
+STRCSPN (const char *str, const char *reject)
{
- size_t count = 0;
+ if (__glibc_unlikely (reject[0] == '\0') ||
+ __glibc_unlikely (reject[1] == '\0'))
+ return __strchrnul (str, reject [0]) - str;
- while (*s != '\0')
- if (strchr (reject, *s++) == NULL)
- ++count;
- else
- 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);
- return count;
+ unsigned char *s = (unsigned char*) reject;
+ unsigned char tmp;
+ do
+ p[tmp = *s++] = 1;
+ while (tmp);
+
+ 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 + 1 : count - c2 + 3;
}
libc_hidden_builtin_def (strcspn)
diff --git a/string/string-inlines.c b/string/string-inlines.c
index 16db3ea..83bdd6c 100644
--- a/string/string-inlines.c
+++ b/string/string-inlines.c
@@ -32,3 +32,43 @@
#undef __NO_INLINE__
#include <bits/string.h>
#include <bits/string2.h>
+
+#include "shlib-compat.h"
+
+#if SHLIB_COMPAT (libc, GLIBC_2_1_1, GLIBC_2_24)
+/* The inline functions are not used from GLIBC 2.24 and forward, however
+ they are required to provide the symbols through string-inlines.c
+ (if inlining is not possible for compatibility reasons). */
+size_t
+__old_strcspn_c1 (const char *__s, int __reject)
+{
+ size_t __result = 0;
+ while (__s[__result] != '\0' && __s[__result] != __reject)
+ ++__result;
+ return __result;
+}
+compat_symbol (libc, __old_strcspn_c1, __strcspn_c1, GLIBC_2_1_1);
+
+size_t
+__old_strcspn_c2 (const char *__s, int __reject1, int __reject2)
+{
+ size_t __result = 0;
+ while (__s[__result] != '\0' && __s[__result] != __reject1
+ && __s[__result] != __reject2)
+ ++__result;
+ return __result;
+}
+compat_symbol (libc, __old_strcspn_c2, __strcspn_c2, GLIBC_2_1_1);
+
+size_t
+__old_strcspn_c3 (const char *__s, int __reject1, int __reject2,
+ int __reject3)
+{
+ size_t __result = 0;
+ while (__s[__result] != '\0' && __s[__result] != __reject1
+ && __s[__result] != __reject2 && __s[__result] != __reject3)
+ ++__result;
+ return __result;
+}
+compat_symbol (libc, __old_strcspn_c3, __strcspn_c3, GLIBC_2_1_1);
+#endif