Re: [PATCH] Replace strcmp_icase with strequal_icase

[Fredrik Gustafsson <iveqy@iveqy.com>]

On Sat, Mar 09, 2013 at 05:54:45PM +0700, Duy Nguyen wrote:
> On Sat, Mar 9, 2013 at 5:40 PM, Duy Nguyen <pclouds@gmail.com> wrote:
> > On Sat, Mar 9, 2013 at 3:42 PM, Fredrik Gustafsson <iveqy@iveqy.com> wrote:
> >> To improve performance.
> >
> > BTW, by rolling our own string comparison, we may lose certain
> > optimizations done by C library. In case of glibc, it may choose to
> > run an sse4.2 version where 16 bytes are compared at a time. Maybe we
> > encounter "string not equal" much often than "string equal" and such
> > an optimization is unncessary, I don't know. Measured numbers say it's
> > unncessary as my cpu supports sse4.2.
> 
> Another problem is locale. Git's toupper() does not care about locale,
> which should be fine in most cases. strcasecmp is locale-aware, our
> new str[n]equal_icase is not. It probably does not matter for
> (ascii-based) pathnames, I guess. core.ignorecase users, any comments?
> -- 
> Duy

Actually when implemented a str[n]equal_icase that actually should work.
I break the test suite when trying to replace
strncmp_icase(pathname, base, baselen)) on line 711 in dir.c and I don't
get any significant improvements.

I like work in this area though, slow commit's are my worst git problem.
I often have to wait 10s. for a commit to be calculated.


-- 
Med vänliga hälsningar
Fredrik Gustafsson

tel: 0733-608274
e-post: iveqy@iveqy.com


From c5d1f436cdbe7b12c67e81cf1d2904d1fb2e9b6b Mon Sep 17 00:00:00 2001
From: Fredrik Gustafsson <iveqy@iveqy.com>
Date: Sat, 9 Mar 2013 09:27:16 +0100
Subject: [PATCH] Replace strcmp_icase with strequal_icase

To improve performance.
git status before:
user    0m0.020s
user    0m0.024s
user    0m0.024s
user    0m0.020s
user    0m0.024s
user    0m0.028s
user    0m0.024s
user    0m0.024s
user    0m0.016s
user    0m0.028s

git status after:
wip

Tried to replace strncmp_icase on line 711 in dir.c but then failed to
run the testsuite. Did not got any relevant speed improvements of this.
---
 dir.c |   49 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 47 insertions(+), 2 deletions(-)

diff --git a/dir.c b/dir.c
index 57394e4..aace36a 100644
--- a/dir.c
+++ b/dir.c
@@ -37,6 +37,51 @@ int fnmatch_icase(const char *pattern, const char *string, int flags)
 	return fnmatch(pattern, string, flags | (ignore_case ? FNM_CASEFOLD : 0));
 }
 
+int strnequal_icase(const char *first, const char *second, size_t count)
+{
+	if (ignore_case) {
+		while (*first && *second && count) {
+			if( toupper(*first) != toupper(*second))
+				break;
+			first++;
+			second++;
+			count--;
+		}
+		return toupper(*first) == toupper(*second);
+	} else {
+		while (*first && *second && count) {
+			if( *first != *second)
+				break;
+			first++;
+			second++;
+			count--;
+		}
+		return *first == *second;
+	}
+
+}
+
+int strequal_icase(const char *first, const char *second)
+{
+	if (ignore_case) {
+		while (*first && *second) {
+			if( toupper(*first) != toupper(*second))
+				break;
+			first++;
+			second++;
+		}
+		return toupper(*first) == toupper(*second);
+	} else {
+		while (*first && *second) {
+			if( *first != *second)
+				break;
+			first++;
+			second++;
+		}
+		return *first == *second;
+	}
+}
+
 inline int git_fnmatch(const char *pattern, const char *string,
 		       int flags, int prefix)
 {
@@ -626,11 +671,11 @@ int match_basename(const char *basename, int basenamelen,
 		   int flags)
 {
 	if (prefix == patternlen) {
-		if (!strcmp_icase(pattern, basename))
+		if (strequal_icase(pattern, basename))
 			return 1;
 	} else if (flags & EXC_FLAG_ENDSWITH) {
 		if (patternlen - 1 <= basenamelen &&
-		    !strcmp_icase(pattern + 1,
+		    strequal_icase(pattern + 1,
 				  basename + basenamelen - patternlen + 1))
 			return 1;
 	} else {
-- 
1.7.2.5