Re: [PATCH] xdiff: optimise for no whitespace difference when ignoring whitespace.
From: Junio C Hamano <hidden>
Date: 2016-06-15 22:49:05
Dylan Reid [off-list ref] writes:
In xdl_recmatch, do the memcmp to check if the two lines are equal before checking if whitespace flags are set. If the lines are identicle, then
"identical"?
there is no need to check if they differ only in whitespace. This makes the common case (there is no whitespace difference) faster. It costs the case where lines are the same length and contain whitespace differences, but the common case is more than 20% faster.
"more than 20% faster" based on what dataset and benchmark?
quoted hunk ↗ jump to hunk
Signed-off-by: Dylan Reid <redacted> --- xdiff/xutils.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)diff --git a/xdiff/xutils.c b/xdiff/xutils.c index bc12f29..22f9bd6 100644 --- a/xdiff/xutils.c +++ b/xdiff/xutils.c@@ -190,8 +190,10 @@ int xdl_recmatch(const char *l1, long s1, const char *l2, long s2, long flags) { int i1, i2; + if (s1 == s2 && !memcmp(l1, l2, s1)) + return 1; if (!(flags & XDF_WHITESPACE_FLAGS)) - return s1 == s2 && !memcmp(l1, l2, s1); + return 0; i1 = 0; i2 = 0;-- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html