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Re: [RFC] Optimize swab operations on mips_r2 cpu

To: Nigel Stephens <nigel@mips.com>
Subject: Re: [RFC] Optimize swab operations on mips_r2 cpu
From: Franck <vagabon.xyz@gmail.com>
Date: Thu, 26 Jan 2006 17:31:27 +0100
Cc: "Kevin D. Kissell" <kevink@mips.com>, linux-mips@linux-mips.org
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2006/1/26, Nigel Stephens <nigel@mips.com>:
>
>
> Kevin D. Kissell wrote:
>
> >Could you please post your mipsel-linux-gcc -v output?   It might help.
> >I've never tried building Linux with any of the Sc/Sd/SmartMIPS options,
> >so I really don't know what you could be experiencing.  One thought that
> >comes to mind is that the -march=4ksd option may be treated as a hint to
> >generate compact code (for smart cards) in a way that -march=mips32r2
> >is not.  I'll ask around...
> >
> >
>
> Assuming that this is the SDE compiler, then I think that the only

yes it is (see my previous post)

> significant thing which -march=4ksd will do differently from
> -march=mips32r2 is to allow the compiler to generate branch-likely
> instructions -- they're deprecated for generic mips32 code but carry no
> penalty on the 4K core. It will also cause the compiler's "4kc" pipeline
> description to be used for instruction scheduling, instead of the
> default "24kc", but that should only change the order of instructions

Do you mean that the code can be run faster when using -march=4ksd ?

> and shouldn't really make a significant difference to the code size.
>

yes but I have :(

Thanks
--
               Franck

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