Re: [PATCH] Replace strcmp_icase with strequal_icase

From: Duy Nguyen <pclouds@gmail.com>
Date: Mar 9, 2013, 10:54 UTC
Message-ID: <CACsJy8BbXjJeTgo0DzKKMY7B3NZB=r3r+Z-WsWJR=t00DkTVzQ@mail.gmail.com>
In-Reply-To: <CACsJy8CphBDKsAAKjCoze98jv=4U+3pN3cW1OYD5XNhYgfcVCA@mail.gmail.com>

On Sat, Mar 9, 2013 at 5:40 PM, Duy Nguyen <pclouds@gmail.com> wrote:

Show 9 quoted lines

> 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