[PATCH] tree_entry_interesting: inline strncmp()
- From
Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
- Date
- Apr 4, 2011, 14:46 UTC
- Message-ID
- <1301928386-25038-1-git-send-email-pclouds@gmail.com>
- In-Reply-To
- <1301535481-1085-3-git-send-email-dpmcgee@gmail.com>
strncmp() is the function that takes most of the time inside tree_entry_interesting(). Inline it so we can shave some seconds out of function call time.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> --- Turns out simplicity is the best. My straight copy of strncmp from glibc performed worse.
With this I get a slightly better performance than Dan's 3/5: 81.07-82.27 secs versus 82.02-82.92 (no other patches are applied). But I'm happy even if it gives the same or slightly worse performance because this applies to more cases than flat top tree case.
Dan, match_dir_prefix() can also use some reordering to avoid strncmp(). But I suppose it won't give much gain on packages.git
tree-walk.c | 28 ++++++++++++++++++++++++---- 1 files changed, 24 insertions(+), 4 deletions(-)
diff --git a/tree-walk.c b/tree-walk.c index 322becc..80bfc3a 100644 --- a/tree-walk.c +++ b/tree-walk.c @@ -457,6 +457,26 @@ int get_tree_entry(const unsigned char *tree_sha1, const char *name, unsigned ch return retval; } +/* Static version of strncmp to reduce function call cost */ +static inline int strncmp_1(const char *s1, const char *s2, size_t n) +{ + unsigned char c1 = '\0'; + unsigned char c2 = '\0'; + + if (!n) + return 0; + + while (n > 0) { + c1 = (unsigned char) *s1++; + c2 = (unsigned char) *s2++; + if (c1 == '\0' || c1 != c2) + return c1 - c2; + n--; + } + + return c1 - c2; +} + static int match_entry(const struct name_entry *entry, int pathlen, const char *match, int matchlen, int *never_interesting) @@ -473,7 +493,7 @@ static int match_entry(const struct name_entry *entry, int pathlen, * Does match sort strictly earlier than path * with their common parts? */ - m = strncmp(match, entry->path, + m = strncmp_1(match, entry->path, (matchlen < pathlen) ? matchlen : pathlen); if (m < 0) return 0; @@ -509,7 +529,7 @@ static int match_entry(const struct name_entry *entry, int pathlen, * we cheated and did not do strncmp(), so we do * that here. */ - m = strncmp(match, entry->path, pathlen); + m = strncmp_1(match, entry->path, pathlen); /* * If common part matched earlier then it is a hit, @@ -525,7 +545,7 @@ static int match_entry(const struct name_entry *entry, int pathlen, static int match_dir_prefix(const char *base, int baselen, const char *match, int matchlen) { - if (strncmp(base, match, matchlen)) + if (strncmp_1(base, match, matchlen)) return 0; /* @@ -592,7 +612,7 @@ int tree_entry_interesting(const struct name_entry *entry, } /* Does the base match? */ - if (!strncmp(base_str, match, baselen)) { + if (!strncmp_1(base_str, match, baselen)) { if (match_entry(entry, pathlen, match + baselen, matchlen - baselen, &never_interesting))
-- 1.7.4.74.g639db