Norihiro Tanaka wrote:
> I rebased this patch, and added four fixes to it.

Thanks.  This patch seems like a real performance win for grep -i in the 
usual case, so I installed it into the master.  If we run into 
performance problems in unusual cases I suppose we can look into them as 
they arise.

In reviewing the patch I found one memory-access typo:

> -              if ((end = memchr(beg, eol, buflim - beg)) != NULL)
> ...
> +              if ((end = memchr(next_beg, eol, buflim - beg)) != NULL)

That last "beg" should be "next_beg".

I merged the patch into the current master on Savannah (first attached 
file) and then applied a fixup patch (second attached file) that fixes 
this bug and makes some other minor related improvements, e.g., using 
memrchr rather than looking for eol by hand.