[PATCH] xdiff: optimise for no whitespace difference when ignoring whitespace.

[Dylan Reid <dgreid@gmail.com>]

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
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.

Signed-off-by: Dylan Reid <dgreid@gmail.com>
---
 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