From: Rebecca Cran <rebecca@bsdio.com>
To: Richard Henderson <richard.henderson@linaro.org>,
qemu-devel@nongnu.org, Michael Tokarev <mjt@tls.msk.ru>,
Laurent Vivier <laurent@vivier.eu>,
qemu-trivial@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] Update the avx2 configure test to be compatible with clang
Date: Fri, 9 Aug 2019 09:17:54 -0600 [thread overview]
Message-ID: <71dd9613-491f-bad3-c31e-231bf51df115@bsdio.com> (raw)
In-Reply-To: <57083e0b-2853-7f5b-16ec-83bc22f237fa@linaro.org>
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
prev parent reply other threads:[~2019-08-09 15:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-09 4:19 [Qemu-devel] [PATCH] Update the avx2 configure test to be compatible with clang Rebecca Cran
2019-08-09 4:52 ` no-reply
2019-08-09 5:22 ` Richard Henderson
2019-08-09 15:17 ` Rebecca Cran [this message]
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