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Re: [Qemu-devel] [PATCH] tcg/ppc: Add vector opcodes

From: Mark Cave-Ayland
Subject: Re: [Qemu-devel] [PATCH] tcg/ppc: Add vector opcodes
Date: Fri, 22 Feb 2019 17:13:37 +0000
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1

On 22/02/2019 05:59, Richard Henderson wrote:

> This requires VSX, not just Altivec, so Power7 or later.
> Signed-off-by: Richard Henderson <address@hidden>
> ---
> At present there are no tunables that can avoid the 64-bit element
> load/store requirement.  As with requiring AVX1 for x86 hosts, I'm
> not sure it's worth inventing such a tunable for pre-power7 hosts.
> Tested vs aarch64 risu test cases.  It's probably worth testing
> this vs Mark's target/ppc conversion.

Oooh this looks really exciting! However... I only have a G4 Mac Mini around 
that I
use for testing which is Altivec-only :(  Is it much work to support non-VSX 

This leads me to a related point that came up when Howard and I were testing 
the PPC
vector patches - how do we know at runtime which optimisations were being used, 
what is the value of have_avx2 on a particular CPU running QEMU?

Under Linux this isn't too bad since you can just do "cat /proc/cpuinfo | grep 
but it becomes more tricky when getting bug reports from Windows users who 
particularly technical...



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