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Re: [Qemu-ppc] [Qemu-devel] [PATCH v3 2/8] target/ppc: rework vmrg{l, h}


From: Richard Henderson
Subject: Re: [Qemu-ppc] [Qemu-devel] [PATCH v3 2/8] target/ppc: rework vmrg{l, h}{b, h, w} instructions to use Vsr* macros
Date: Sun, 27 Jan 2019 09:26:02 -0800
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0

On 1/27/19 7:19 AM, Mark Cave-Ayland wrote:
> Could this make the loop slower? I certainly haven't noticed any obvious
> performance difference during testing (OS X uses merge quite a bit for
> display rendering), and I'd hope that with a good compiler and modern branch
> prediction then any effect here would be negligible.
I would expect the i < n/2 loop to be faster, because the assignments are
unconditional.  FWIW.


r~



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