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Re: [Qemu-devel] [PATCH] RFC: TCG constant propagation.

From: Filip Navara
Subject: Re: [Qemu-devel] [PATCH] RFC: TCG constant propagation.
Date: Wed, 5 Aug 2009 10:48:05 +0200

On Wed, Aug 5, 2009 at 10:13 AM, Pablo
Virolainen<address@hidden> 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
> address@hidden 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

Best regards,
Filip Navara

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