diff options
| -rw-r--r-- | ChangeLog | 5 | ||||
| -rw-r--r-- | string/strcasestr.c | 37 | ||||
| -rw-r--r-- | string/strstr.c | 43 |
3 files changed, 40 insertions, 45 deletions
diff --git a/ChangeLog b/ChangeLog index d21bdbcce8..22012fb458 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,10 @@ 2019-09-13 Wilco Dijkstra <wdijkstr@arm.com> + * string/strcasestr.c (STRCASESTR): Simplify and speedup first match. + * string/strstr.c (AVAILABLE): Likewise. + +2019-09-13 Wilco Dijkstra <wdijkstr@arm.com> + * benchtests/bench-strcasestr.c: Rename __strnlen to strnlen. * benchtests/bench-strstr.c: Likewise. * string/memmem.c (FASTSEARCH): Define. diff --git a/string/strcasestr.c b/string/strcasestr.c index 7caaade5d2..772e513626 100644 --- a/string/strcasestr.c +++ b/string/strcasestr.c @@ -58,31 +58,22 @@ case-insensitive comparison. This function gives unspecified results in multibyte locales. */ char * -STRCASESTR (const char *haystack_start, const char *needle_start) +STRCASESTR (const char *haystack, const char *needle) { - const char *haystack = haystack_start; - const char *needle = needle_start; size_t needle_len; /* Length of NEEDLE. */ size_t haystack_len; /* Known minimum length of HAYSTACK. */ - bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */ - - /* Determine length of NEEDLE, and in the process, make sure - HAYSTACK is at least as long (no point processing all of a long - NEEDLE if HAYSTACK is too short). */ - while (*haystack && *needle) - { - ok &= (TOLOWER ((unsigned char) *haystack) - == TOLOWER ((unsigned char) *needle)); - haystack++; - needle++; - } - if (*needle) + + /* Handle empty NEEDLE special case. */ + if (needle[0] == '\0') + return (char *) haystack; + + /* Ensure HAYSTACK length is at least as long as NEEDLE length. + Since a match may occur early on in a huge HAYSTACK, use strnlen + and read ahead a few cachelines for improved performance. */ + needle_len = strlen (needle); + haystack_len = __strnlen (haystack, needle_len + 256); + if (haystack_len < needle_len) return NULL; - if (ok) - return (char *) haystack_start; - needle_len = needle - needle_start; - haystack = haystack_start + 1; - haystack_len = needle_len - 1; /* Perform the search. Abstract memory is considered to be an array of 'unsigned char' values, not an array of 'char' values. See @@ -90,10 +81,10 @@ STRCASESTR (const char *haystack_start, const char *needle_start) if (needle_len < LONG_NEEDLE_THRESHOLD) return two_way_short_needle ((const unsigned char *) haystack, haystack_len, - (const unsigned char *) needle_start, + (const unsigned char *) needle, needle_len); return two_way_long_needle ((const unsigned char *) haystack, haystack_len, - (const unsigned char *) needle_start, + (const unsigned char *) needle, needle_len); } diff --git a/string/strstr.c b/string/strstr.c index 63facae4a5..1eb4dc11db 100644 --- a/string/strstr.c +++ b/string/strstr.c @@ -50,33 +50,32 @@ if NEEDLE is empty, otherwise NULL if NEEDLE is not found in HAYSTACK. */ char * -STRSTR (const char *haystack_start, const char *needle_start) +STRSTR (const char *haystack, const char *needle) { - const char *haystack = haystack_start; - const char *needle = needle_start; size_t needle_len; /* Length of NEEDLE. */ size_t haystack_len; /* Known minimum length of HAYSTACK. */ - bool ok = true; /* True if NEEDLE is prefix of HAYSTACK. */ - - /* Determine length of NEEDLE, and in the process, make sure - HAYSTACK is at least as long (no point processing all of a long - NEEDLE if HAYSTACK is too short). */ - while (*haystack && *needle) - ok &= *haystack++ == *needle++; - if (*needle) + + /* Handle empty NEEDLE special case. */ + if (needle[0] == '\0') + return (char *) haystack; + + /* Skip until we find the first matching char from NEEDLE. */ + haystack = strchr (haystack, needle[0]); + if (haystack == NULL || needle[1] == '\0') + return (char *) haystack; + + /* Ensure HAYSTACK length is at least as long as NEEDLE length. + Since a match may occur early on in a huge HAYSTACK, use strnlen + and read ahead a few cachelines for improved performance. */ + needle_len = strlen (needle); + haystack_len = __strnlen (haystack, needle_len + 256); + if (haystack_len < needle_len) return NULL; - if (ok) - return (char *) haystack_start; - - /* Reduce the size of haystack using strchr, since it has a smaller - linear coefficient than the Two-Way algorithm. */ - needle_len = needle - needle_start; - haystack = strchr (haystack_start + 1, *needle_start); - if (!haystack || __builtin_expect (needle_len == 1, 0)) + + /* Check whether we have a match. This improves performance since we avoid + the initialization overhead of the two-way algorithm. */ + if (memcmp (haystack, needle, needle_len) == 0) return (char *) haystack; - needle -= needle_len; - haystack_len = (haystack > haystack_start + needle_len ? 1 - : needle_len + haystack_start - haystack); /* Perform the search. Abstract memory is considered to be an array of 'unsigned char' values, not an array of 'char' values. See |