From c8dd67e7c958de04c3783cbea7c384431707b5f8 Mon Sep 17 00:00:00 2001 From: Rajalakshmi Srinivasaraghavan Date: Tue, 28 Aug 2018 12:42:19 +0530 Subject: Speedup first memmem match As done in commit 284f42bc778e487dfd5dff5c01959f93b9e0c4f5, memcmp can be used after memchr to avoid the initialization overhead of the two-way algorithm for the first match. This has shown improvement >40% for first match. --- ChangeLog | 4 ++++ string/memmem.c | 4 ++++ 2 files changed, 8 insertions(+) diff --git a/ChangeLog b/ChangeLog index 8419d4671c..2a250970e4 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,7 @@ +2018-08-28 Rajalakshmi Srinivasaraghavan + + * string/memmem.c: Use memcmp for first match. + 2018-08-28 Rafal Luzynski [BZ #17426] diff --git a/string/memmem.c b/string/memmem.c index 43efaa3fb7..d72b8249e6 100644 --- a/string/memmem.c +++ b/string/memmem.c @@ -70,6 +70,10 @@ __memmem (const void *haystack_start, size_t haystack_len, haystack_len -= haystack - (const unsigned char *) haystack_start; if (haystack_len < needle_len) return NULL; + /* 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 (void *) haystack; return two_way_short_needle (haystack, haystack_len, needle, needle_len); } else -- cgit v1.2.1