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Date: Wed, 5 Aug 2009 10:48:05 +0200
Message-ID: <5b31733c0908050148m512aa221p70ba8b3e56699203@mail.gmail.com>
Subject: Re: [Qemu-devel] [PATCH] RFC: TCG constant propagation.
From: Filip Navara <filip.navara@gmail.com>
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To: Pablo Virolainen <Pablo.Virolainen@nomovok.com>
Cc: qemu-devel@nongnu.org

On Wed, Aug 5, 2009 at 10:13 AM, Pablo
Virolainen<Pablo.Virolainen@nomovok.com> wrote:
> Filip Navara kirjoitti:
>>
>> Add support for constant propagation to TCG. This has to be paired with
>> the liveness
>> analysis to remove the dead code. Not all possible operations are covered,
>> but the
>> most common ones are. This improves the code generation for several ARM
>> instructions,
>> like MVN (immediate), and it may help other targets as well.
>
> On my small benchmark, qemu-system-sh4 was about 3% slower on Intel Xeon
> E5405@2.00GHz. I'm running 64-bit mode. My mini benchmark is to build zlib
> 1.2.3, so it's 'real' world work load. Ran the benchmark several times and
> results seems to be pretty constant.

Thanks for testing and reporting the results. I'll see if I can reduce
the overhead or if I should ditch the patch.

> ps. I added INDEX_op_*_i64 cases to the evaluation part. I'm not completly
> sure if those &mask should be there.

I've rewritten the patch and fixed the 64-bit mess that was there. It
is available at
http://repo.or.cz/w/qemu/navara.git?a=commit;h=5df3a524fc0b923cf2e5e1883ff550d055d36eb5

Best regards,
Filip Navara