Re: [PATCH-v2/RFC 3/6] xutils: fix ignore-all-space on incomplete line

Junio C Hamano (gitster@pobox.com) wrote on Aug 23, 2009:

Thell Fowler [off-list ref] writes:

quoted

quoted

Or we can just move the final else clause up and start the function like
this:

	int i1, i2;

	if (!(flags & XDF_WHITESPACE_FLAGS))
 		return s1 == s2 && !memcmp(l1, l2, s1);

	i1 = i2 = 0;
 	if (flags & XDF_IGNORE_WHITESPACE) {
		...

that would get rid of two unnecessary clearing of variables (i1 and i2,
even though I suspect that the compiler _could_ optimize them out without
such an change), and three flags-bit check in the most common case of not
ignoring any whitespaces.

HA!  That's a nifty way to do that with the variables.

My tentative draft to replace the "how about this" patch further reworks
the loop structure and currently looks like this.

It adds net 15 lines but among that 12 lines are comments, which is not so
bad.

It passed every test I threw at it, although it seemed to be a tad bit 
slower than the previous revision on my sample data so I ran the following 
command several times for both the previous and current version:

time for i in {1..10}; do ./t4015-diff-whitespace.sh>/dev/null && 
./t4015-diff-trailing-whitespace.sh >/dev/null; done


And these results are fairly average on what I saw:

Previous version:
real	2m32.669s
user	0m44.051s
sys	1m34.702s


Current version:
real	2m56.818s
user	0m47.671s
sys	1m46.723s

--
Thell