From: Rich Felker <dalias@aerifal.cx>
To: musl@lists.openwall.com
Subject: Re: Thinking about release
Date: Wed, 10 Jul 2013 17:01:49 -0400 [thread overview]
Message-ID: <20130710210149.GG29800@brightrain.aerifal.cx> (raw)
In-Reply-To: <CAPfzE3a1firnZq0mN=Psru8Csz0LGcJ+B2GuKej0QDfYJbCsJA@mail.gmail.com>
On Thu, Jul 11, 2013 at 08:34:03AM +1200, Andre Renaud wrote:
> >> What also might be worth testing is whether GCC can compete if you
> >> just give it a naive loop (not the fancy pseudo-vectorized stuff
> >> currently in musl) and good CFLAGS. I know on x86 I was able to beat
> >> the fanciest asm strlen I could come up with simply by writing the
> >> naive loop in C and unrolling it a lot.
> >
> >
> > Duff's device!
>
> That was exactly my first idea too, but interestingly it turns out not
> to have really added any performance improvement. Looking at the
> assembler, with -O3, gcc does a pretty good job of unrolling as it is.
For what it's worth, my testing showed the current memcpy code in musl
and the naive "while (n--) *d++=*s++;" version performing
near-identically at -O3, and both got about 20% faster with
-funroll-all-loops. With -O2 or -Os, the naive version was about 5
times slower.
Rich
next prev parent reply other threads:[~2013-07-10 21:01 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-13 1:25 Rich Felker
2013-06-13 1:33 ` Andre Renaud
2013-06-13 1:43 ` Rich Felker
2013-07-09 5:06 ` Andre Renaud
2013-07-09 5:37 ` Rich Felker
2013-07-09 6:24 ` Harald Becker
2013-07-09 21:28 ` Andre Renaud
2013-07-09 22:26 ` Andre Renaud
2013-07-10 6:42 ` Jens Gustedt
2013-07-10 7:50 ` Rich Felker
2013-07-10 22:44 ` Andre Renaud
2013-07-11 3:37 ` Rich Felker
2013-07-11 4:04 ` Andre Renaud
2013-07-11 5:10 ` Andre Renaud
2013-07-11 12:46 ` Rich Felker
2013-07-11 22:34 ` Andre Renaud
2013-07-12 3:16 ` Rich Felker
2013-07-12 3:36 ` Andre Renaud
2013-07-12 4:16 ` Rich Felker
2013-07-24 1:34 ` Andre Renaud
2013-07-24 3:48 ` Rich Felker
2013-07-24 4:40 ` Andre Renaud
2013-07-28 8:09 ` Rich Felker
2013-07-11 5:27 ` Daniel Cegiełka
2013-07-11 12:49 ` Rich Felker
2013-07-15 4:25 ` Rob Landley
2013-07-10 19:42 ` Rich Felker
2013-07-14 6:37 ` Rob Landley
2013-07-11 4:30 ` Strake
2013-07-11 4:33 ` Rich Felker
2013-07-10 19:38 ` Rob Landley
2013-07-10 20:34 ` Andre Renaud
2013-07-10 20:49 ` Nathan McSween
2013-07-10 21:01 ` Rich Felker [this message]
2013-06-13 15:46 ` Isaac
2013-06-26 1:44 ` Rich Felker
2013-06-26 10:19 ` Szabolcs Nagy
2013-06-26 14:21 ` Rich Felker
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