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| author | Wilco Dijkstra <wdijkstr@arm.com> | 2018-07-16 17:50:09 +0100 |
|---|---|---|
| committer | Wilco Dijkstra <wdijkstr@arm.com> | 2018-07-16 17:51:52 +0100 |
| commit | 3ae725dfb6d7f61447d27d00ed83e573bd5454f4 (patch) | |
| tree | 1a0eada529fc06de4613cb84a20d80e5d69c6d0a /string/strcasestr.c | |
| parent | 31e422ca9680bbe412aa56b23f058c10eaee7be8 (diff) | |
| download | glibc-3ae725dfb6d7f61447d27d00ed83e573bd5454f4.tar.gz | |
Improve strstr performance
Improve strstr performance. Strstr tends to be slow because it uses
many calls to memchr and a slow byte loop to scan for the next match.
Performance is significantly improved by using strnlen on larger blocks
and using strchr to search for the next matching character. strcasestr
can also use strnlen to scan ahead, and memmem can use memchr to check
for the next match.
On the GLIBC bench tests the performance gains on Cortex-A72 are:
strstr: +25%
strcasestr: +4.3%
memmem: +18%
On a 256KB dataset strstr performance improves by 67%, strcasestr by 47%.
Reviewd-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Diffstat (limited to 'string/strcasestr.c')
| -rw-r--r-- | string/strcasestr.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/string/strcasestr.c b/string/strcasestr.c index 90ba189790..5909fe3cdb 100644 --- a/string/strcasestr.c +++ b/string/strcasestr.c @@ -37,8 +37,8 @@ /* Two-Way algorithm. */ #define RETURN_TYPE char * #define AVAILABLE(h, h_l, j, n_l) \ - (!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l)) \ - && ((h_l) = (j) + (n_l))) + (((j) + (n_l) <= (h_l)) || ((h_l) += __strnlen ((void*)((h) + (h_l)), 512), \ + (j) + (n_l) <= (h_l))) #define CHECK_EOL (1) #define RET0_IF_0(a) if (!a) goto ret0 #define CANON_ELEMENT(c) TOLOWER (c) |