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From: Artyom Tarasenko <atar4qemu@gmail.com>
Date: Mon, 17 Aug 2015 16:19:26 +0200
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Subject: Re: [Qemu-devel] Debian 7.8.0 SPARC64 on qemu - anything i can do
 to speedup the emulation?
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To: Aurelien Jarno <aurelien@aurel32.net>
Cc: Richard Henderson <rth@twiddle.net>, alex.bennee@linaro.org, qemu-devel <qemu-devel@nongnu.org>, Dennis Luehring <dl.soluz@gmx.net>, Karel Gardas <gardask@gmail.com>

On Thu, Jul 30, 2015 at 9:55 AM, Aurelien Jarno <aurelien@aurel32.net> wrote:
> On 2015-07-30 05:47, Dennis Luehring wrote:
>> so your aarch64 is just less todo for qemu - not EVERY >= 16bit memory
>> access needs swapping or needs check for unaligned access to emulate
>> bus-erros
>
> On recent Intel CPU, the byteswapping comes for free (MOVBE
> instruction).
>
> About the unaligned access it's actually the reverse. The fact that
> aarch64 does unaligned access means they have to go through the slow
> path (I have posted a patch to improve that). On sparc given that all
> access are aligned means there are more chances to go through the fast
> path.

Well, on the other hand, every access goes via helper_check_align.
There is a comment /* XXX remove alignment check */.
I wonder how this can be done in a  more efficient way?
Inlining the check and using a brcond instruction would require that
all TCG temps would have to be changed to locals, which in turn would
produce a performance impact. Are there other ways of doing it?

Artyom

-- 
Regards,
Artyom Tarasenko

SPARC and PPC PReP under qemu blog: http://tyom.blogspot.com/search/label/qemu