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Re: [Qemu-trivial] [Qemu-devel] [PATCH] Update the avx2 configure test t

From: Rebecca Cran
Subject: Re: [Qemu-trivial] [Qemu-devel] [PATCH] Update the avx2 configure test to be compatible with clang
Date: Fri, 9 Aug 2019 09:17:54 -0600
User-agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0

On 2019-08-08 23:22, Richard Henderson wrote:
> No, this means we're not testing what we need:
> We need to compile exactly one function using avx2.
> The other functions should be compiled with sse4 and sse2, respectively, and 
> we
> choose between them by testing cpuid bits at startup.  If you supply -mavx2 to
> the entire compilation, then the routine that is supposed to use only sse2 
> will
> in fact use avx2, and then the runtime selection is moot.

Oh, sorry, I hadn't fully realized there's runtime selection. Fixing
this would require significant rework in that case, so I'll just build
with GCC instead for now!

Rebecca Cran

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