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Date: Thu, 11 Jul 2013 08:49:03 -0400
From: Rich Felker <dalias@...ifal.cx>
To: musl@...ts.openwall.com
Subject: Re: Thinking about release
On Thu, Jul 11, 2013 at 07:27:11AM +0200, Daniel Cegiełka wrote:
> 2013/7/11 Rich Felker <dalias@...ifal.cx>:
> > On Thu, Jul 11, 2013 at 10:44:16AM +1200, Andre Renaud wrote:
>
> > Yes, I suspect so. One slightly crazy idea I had was to write the
> > function in C with just inline asm for the inner ldm/stm loop.
>
> A bit of useful code (x86):
>
> http://dpdk.org/browse/dpdk/tree/lib/librte_eal/common/include/rte_memcpy.h
On modern x86 (32-bit), this is slower than even the naive "rep movsb"
version. Some x86 chips have problems with rep movsb, so the version
in musl does a little bit more work (possibly more than it needs to)
to use "rep movsd".
On x86_64, there _may_ be faster approaches than the "rep movsq" we
have right now, but so far my impression is that they don't work on
baseline x86_64 (only later variants) and don't gain much.
Rich
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