From: Szabolcs Nagy <nsz@port70.net>
To: musl@lists.openwall.com
Subject: Re: ARM optimisations
Date: Sat, 2 Mar 2013 12:34:41 +0100 [thread overview]
Message-ID: <20130302113441.GQ6181@port70.net> (raw)
In-Reply-To: <1362198799.21837.5@driftwood>
* Rob Landley <rob@landley.net> [2013-03-01 22:33:19 -0600]:
> I'd actually say that armv5 is probably the one to optimize for,
> because it's somewhere over 80% of the installed base of arm systems
> and generally provides an additonal 25% speedup from armv4 to armv5.
> Anything lower than that can use C, anything newer than that can
> benefit from an armv5 version vs C.
...
> I believe armv6 was mostly just SMP extensions, so not worth
> optimizing memcpy for. armv7 is nice but not uibiquitous the way
> armv5 is, and armv7 brings with it the "thumb2" instruction set
> which means you'd need 2 versions depending on what target you
> wanted to compile for...
a quick research shows that
glibc has ifdefs for armv5te and armv4t optimizations
http://sourceware.org/git/?p=glibc.git;a=blob;f=ports/sysdeps/arm/memcpy.S
linaro has armv7 optimized version
http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/view/head:/src/linaro-a9/memcpy.S
olibc (the bionic one not the openbsd one) has armv7+neon optimized memcpy
https://github.com/olibc/olibc/blob/master/libc/arch-arm/bionic/memcpy.S
next prev parent reply other threads:[~2013-03-02 11:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-28 23:15 Andre Renaud
2013-02-28 23:30 ` Rich Felker
2013-03-02 4:33 ` Rob Landley
2013-03-02 6:21 ` Rich Felker
2013-03-04 18:55 ` Rob Landley
2013-03-02 11:34 ` Szabolcs Nagy [this message]
2013-03-02 20:33 ` Andre Renaud
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