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authorWilco Dijkstra <wdijkstr@arm.com>2016-12-21 15:16:29 +0000
committerWilco Dijkstra <wdijkstr@arm.com>2016-12-21 15:16:29 +0000
commit5625f666cead9f3c71e00696df2907120aef1f31 (patch)
tree38d3bbb125573116a83930aa30d6d89d93f9a14e
parentd08ab9ced75e0d88827e0bb58183612afb7fe1fd (diff)
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This patch cleans up the strsep implementation and improves performance.
Currently strsep calls strpbrk is is now a veneer to strcspn. Calling strcspn directly is faster. Since it handles a delimiter string of size 1 as a special case, this is not needed in strsep itself. Although this means there is a slightly higher overhead if the delimiter size is 1, all other cases are slightly faster. The overall performance gain is 5-10% on AArch64. The string/bits/string2.h header contains optimizations for constant delimiters of size 1-3. Benchmarking these showed similar performance for size 1 (since in all cases strchr/strchrnul is used), while size 2 and 3 can give up to 2x speedup for small input strings. However if these cases are common it seems much better to add this optimization to strcspn. So move these header optimizations to string-inlines.c. Improve the strsep benchmark so that it actually benchmarks something. The current version contains a delimiter character at every position in the input string, so there is very little work to do, and the extremely inefficent simple_strsep implementation appears fastest in every case. The new version has either no match in the input for the fail case and a match halfway in the input for the success case. The input is then restored so that each iteration does exactly the same amount of work. Reduce the number of testcases since simple_strsep takes a lot of time now. * benchtests/bench-strsep.c (oldstrsep): Add old implementation. (do_one_test) Restore original string so iteration works. * string/string-inlines.c (do_test): Create better input strings. (test_main) Reduce number of testruns. * string/string-inlines.c (__old_strsep_1c): New function. (__old_strsep_2c): Likewise. (__old_strsep_3c): Likewise. * string/strsep.c (__strsep): Remove case of small delim string. Call strcspn directly rather than strpbrk. * string/bits/string2.h (__strsep): Remove define. (__strsep_1c): Remove. (__strsep_2c): Remove. (__strsep_3c): Remove. (strsep): Remove. * sysdeps/unix/sysv/linux/internal_statvfs.c (__statvfs_getflags): Rename to __strsep.
-rw-r--r--ChangeLog19
-rw-r--r--benchtests/bench-strsep.c79
-rw-r--r--string/bits/string2.h90
-rw-r--r--string/string-inlines.c64
-rw-r--r--string/strsep.c26
-rw-r--r--sysdeps/unix/sysv/linux/internal_statvfs.c2
6 files changed, 145 insertions, 135 deletions
diff --git a/ChangeLog b/ChangeLog
index b8436d37f6..8e8c0a3f6b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,22 @@
+2015-12-21 Wilco Dijkstra <wdijkstr@arm.com>
+
+ * benchtests/bench-strsep.c (oldstrsep): Add old implementation.
+ (do_one_test) Restore original string so iteration works.
+ * string/string-inlines.c (do_test): Create better input strings.
+ (test_main) Reduce number of testruns.
+ * string/string-inlines.c (__old_strsep_1c): New function.
+ (__old_strsep_2c): Likewise.
+ (__old_strsep_3c): Likewise.
+ * string/strsep.c (__strsep): Remove case of small delim string.
+ Call strcspn directly rather than strpbrk.
+ * string/bits/string2.h (__strsep): Remove define.
+ (__strsep_1c): Remove.
+ (__strsep_2c): Remove.
+ (__strsep_3c): Remove.
+ (strsep): Remove.
+ * sysdeps/unix/sysv/linux/internal_statvfs.c
+ (__statvfs_getflags): Rename to __strsep.
+
2016-12-21 Florian Weimer <fweimer@redhat.com>
* csu/libc-tls.c (_dl_tls_setup): Remove.
diff --git a/benchtests/bench-strsep.c b/benchtests/bench-strsep.c
index 774a093431..4a53b4f449 100644
--- a/benchtests/bench-strsep.c
+++ b/benchtests/bench-strsep.c
@@ -49,10 +49,56 @@ simple_strsep (char **s1, char *s2)
return begin;
}
+char *
+oldstrsep (char **stringp, const char *delim)
+{
+ char *begin, *end;
+
+ begin = *stringp;
+ if (begin == NULL)
+ return NULL;
+
+ /* A frequent case is when the delimiter string contains only one
+ character. Here we don't need to call the expensive `strpbrk'
+ function and instead work using `strchr'. */
+ if (delim[0] == '\0' || delim[1] == '\0')
+ {
+ char ch = delim[0];
+
+ if (ch == '\0')
+ end = NULL;
+ else
+ {
+ if (*begin == ch)
+ end = begin;
+ else if (*begin == '\0')
+ end = NULL;
+ else
+ end = strchr (begin + 1, ch);
+ }
+ }
+ else
+ /* Find the end of the token. */
+ end = strpbrk (begin, delim);
+
+ if (end)
+ {
+ /* Terminate the token and set *STRINGP past NUL character. */
+ *end++ = '\0';
+ *stringp = end;
+ }
+ else
+ /* No more delimiters; this is the last token. */
+ *stringp = NULL;
+
+ return begin;
+}
+
typedef char *(*proto_t) (const char **, const char *);
IMPL (simple_strsep, 0)
IMPL (strsep, 1)
+IMPL (oldstrsep, 2)
static void
do_one_test (impl_t * impl, const char *s1, const char *s2)
@@ -63,7 +109,10 @@ do_one_test (impl_t * impl, const char *s1, const char *s2)
TIMING_NOW (start);
for (i = 0; i < iters; ++i)
{
- CALL (impl, &s1, s2);
+ const char *s1a = s1;
+ CALL (impl, &s1a, s2);
+ if (s1a != NULL)
+ ((char*)s1a)[-1] = '1';
}
TIMING_NOW (stop);
@@ -76,7 +125,10 @@ static void
do_test (size_t align1, size_t align2, size_t len1, size_t len2, int fail)
{
char *s2 = (char *) (buf2 + align2);
- static const char d[] = "1234567890abcdef";
+
+ /* Search for a delimiter in a string containing mostly '0', so don't
+ use '0' as a delimiter. */
+ static const char d[] = "123456789abcdefg";
#define dl (sizeof (d) - 1)
char *ss2 = s2;
for (size_t l = len2; l > 0; l = l > dl ? l - dl : 0)
@@ -92,24 +144,9 @@ do_test (size_t align1, size_t align2, size_t len1, size_t len2, int fail)
FOR_EACH_IMPL (impl, 0)
{
char *s1 = (char *) (buf1 + align1);
- if (fail)
- {
- char *ss1 = s1;
- for (size_t l = len1; l > 0; l = l > dl ? l - dl : 0)
- {
- size_t t = l > dl ? dl : l;
- memcpy (ss1, d, t);
- ++ss1[len2 > 7 ? 7 : len2 - 1];
- ss1 += t;
- }
- }
- else
- {
- memset (s1, '0', len1);
- memcpy (s1 + (len1 - len2) - 2, s2, len2);
- if ((len1 / len2) > 4)
- memcpy (s1 + (len1 - len2) - (3 * len2), s2, len2);
- }
+ memset (s1, '0', len1);
+ if (!fail)
+ s1[len1 / 2] = '1';
s1[len1] = '\0';
do_one_test (impl, s1, s2);
}
@@ -127,7 +164,7 @@ test_main (void)
putchar ('\n');
for (size_t klen = 2; klen < 32; ++klen)
- for (size_t hlen = 2 * klen; hlen < 16 * klen; hlen += klen)
+ for (size_t hlen = 4 * klen; hlen < 8 * klen; hlen += klen)
{
do_test (0, 0, hlen, klen, 0);
do_test (0, 0, hlen, klen, 1);
diff --git a/string/bits/string2.h b/string/bits/string2.h
index e39d4f1a85..c1366172fa 100644
--- a/string/bits/string2.h
+++ b/string/bits/string2.h
@@ -180,96 +180,6 @@ extern void *__rawmemchr (const void *__s, int __c);
#endif
-#if !defined _HAVE_STRING_ARCH_strsep || defined _FORCE_INLINES
-# ifndef _HAVE_STRING_ARCH_strsep
-
-extern char *__strsep_g (char **__stringp, const char *__delim);
-# define __strsep(s, reject) \
- __extension__ \
- ({ char __r0, __r1, __r2; \
- (__builtin_constant_p (reject) && __string2_1bptr_p (reject) \
- && (__r0 = ((const char *) (reject))[0], \
- ((const char *) (reject))[0] != '\0') \
- ? ((__r1 = ((const char *) (reject))[1], \
- ((const char *) (reject))[1] == '\0') \
- ? __strsep_1c (s, __r0) \
- : ((__r2 = ((const char *) (reject))[2], __r2 == '\0') \
- ? __strsep_2c (s, __r0, __r1) \
- : (((const char *) (reject))[3] == '\0' \
- ? __strsep_3c (s, __r0, __r1, __r2) \
- : __strsep_g (s, reject)))) \
- : __strsep_g (s, reject)); })
-# endif
-
-__STRING_INLINE char *__strsep_1c (char **__s, char __reject);
-__STRING_INLINE char *
-__strsep_1c (char **__s, char __reject)
-{
- char *__retval = *__s;
- if (__retval != NULL && (*__s = strchr (__retval, __reject)) != NULL)
- *(*__s)++ = '\0';
- return __retval;
-}
-
-__STRING_INLINE char *__strsep_2c (char **__s, char __reject1, char __reject2);
-__STRING_INLINE char *
-__strsep_2c (char **__s, char __reject1, char __reject2)
-{
- char *__retval = *__s;
- if (__retval != NULL)
- {
- char *__cp = __retval;
- while (1)
- {
- if (*__cp == '\0')
- {
- __cp = NULL;
- break;
- }
- if (*__cp == __reject1 || *__cp == __reject2)
- {
- *__cp++ = '\0';
- break;
- }
- ++__cp;
- }
- *__s = __cp;
- }
- return __retval;
-}
-
-__STRING_INLINE char *__strsep_3c (char **__s, char __reject1, char __reject2,
- char __reject3);
-__STRING_INLINE char *
-__strsep_3c (char **__s, char __reject1, char __reject2, char __reject3)
-{
- char *__retval = *__s;
- if (__retval != NULL)
- {
- char *__cp = __retval;
- while (1)
- {
- if (*__cp == '\0')
- {
- __cp = NULL;
- break;
- }
- if (*__cp == __reject1 || *__cp == __reject2 || *__cp == __reject3)
- {
- *__cp++ = '\0';
- break;
- }
- ++__cp;
- }
- *__s = __cp;
- }
- return __retval;
-}
-# ifdef __USE_MISC
-# define strsep(s, reject) __strsep (s, reject)
-# endif
-#endif
-
/* We need the memory allocation functions for inline strdup().
Referring to stdlib.h (even minimally) is not allowed
in any of the tight standards compliant modes. */
diff --git a/string/string-inlines.c b/string/string-inlines.c
index d43e5897c3..7b1de7180f 100644
--- a/string/string-inlines.c
+++ b/string/string-inlines.c
@@ -63,6 +63,70 @@ __old_strtok_r_1c (char *__s, char __sep, char **__nextp)
return __result;
}
compat_symbol (libc, __old_strtok_r_1c, __strtok_r_1c, GLIBC_2_1_1);
+
+char *
+__old_strsep_1c (char **__s, char __reject)
+{
+ char *__retval = *__s;
+ if (__retval != NULL && (*__s = strchr (__retval, __reject)) != NULL)
+ *(*__s)++ = '\0';
+ return __retval;
+}
+compat_symbol (libc, __old_strsep_1c, __strsep_1c, GLIBC_2_1_1);
+
+char *
+__old_strsep_2c (char **__s, char __reject1, char __reject2)
+{
+ char *__retval = *__s;
+ if (__retval != NULL)
+ {
+ char *__cp = __retval;
+ while (1)
+ {
+ if (*__cp == '\0')
+ {
+ __cp = NULL;
+ break;
+ }
+ if (*__cp == __reject1 || *__cp == __reject2)
+ {
+ *__cp++ = '\0';
+ break;
+ }
+ ++__cp;
+ }
+ *__s = __cp;
+ }
+ return __retval;
+}
+compat_symbol (libc, __old_strsep_2c, __strsep_2c, GLIBC_2_1_1);
+
+char *
+__old_strsep_3c (char **__s, char __reject1, char __reject2, char __reject3)
+{
+ char *__retval = *__s;
+ if (__retval != NULL)
+ {
+ char *__cp = __retval;
+ while (1)
+ {
+ if (*__cp == '\0')
+ {
+ __cp = NULL;
+ break;
+ }
+ if (*__cp == __reject1 || *__cp == __reject2 || *__cp == __reject3)
+ {
+ *__cp++ = '\0';
+ break;
+ }
+ ++__cp;
+ }
+ *__s = __cp;
+ }
+ return __retval;
+}
+compat_symbol (libc, __old_strsep_3c, __strsep_3c, GLIBC_2_1_1);
#endif
#if SHLIB_COMPAT (libc, GLIBC_2_1_1, GLIBC_2_24)
diff --git a/string/strsep.c b/string/strsep.c
index 1054774048..68581c8639 100644
--- a/string/strsep.c
+++ b/string/strsep.c
@@ -29,30 +29,10 @@ __strsep (char **stringp, const char *delim)
if (begin == NULL)
return NULL;
- /* A frequent case is when the delimiter string contains only one
- character. Here we don't need to call the expensive `strpbrk'
- function and instead work using `strchr'. */
- if (delim[0] == '\0' || delim[1] == '\0')
- {
- char ch = delim[0];
-
- if (ch == '\0')
- end = NULL;
- else
- {
- if (*begin == ch)
- end = begin;
- else if (*begin == '\0')
- end = NULL;
- else
- end = strchr (begin + 1, ch);
- }
- }
- else
- /* Find the end of the token. */
- end = strpbrk (begin, delim);
+ /* Find the end of the token. */
+ end = begin + strcspn (begin, delim);
- if (end)
+ if (*end)
{
/* Terminate the token and set *STRINGP past NUL character. */
*end++ = '\0';
diff --git a/sysdeps/unix/sysv/linux/internal_statvfs.c b/sysdeps/unix/sysv/linux/internal_statvfs.c
index 012f93fe66..ce649cd28d 100644
--- a/sysdeps/unix/sysv/linux/internal_statvfs.c
+++ b/sysdeps/unix/sysv/linux/internal_statvfs.c
@@ -168,7 +168,7 @@ __statvfs_getflags (const char *name, int fstype, int fd)
char *cp = mntbuf.mnt_opts;
char *opt;
- while ((opt = strsep (&cp, ",")) != NULL)
+ while ((opt = __strsep (&cp, ",")) != NULL)
if (strcmp (opt, "ro") == 0)
result |= ST_RDONLY;
else if (strcmp (opt, "nosuid") == 0)