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[Bug math/21967] When 512-bit AVX2 wrapper functions in mathvec are used?
- From: "hjl.tools at gmail dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sourceware dot org
- Date: Fri, 18 Aug 2017 17:47:14 +0000
- Subject: [Bug math/21967] When 512-bit AVX2 wrapper functions in mathvec are used?
- Auto-submitted: auto-generated
- References: <bug-21967-131@http.sourceware.org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=21967
--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> ---
avx2_wrapper is supposed to be used when AVX512F isn't profitable. But
with
if (CPU_FEATURES_ARCH_P (cpu_features, AVX512DQ_Usable))
return OPTIMIZE (skx);
if (CPU_FEATURES_ARCH_P (cpu_features, AVX512F_Usable))
return OPTIMIZE (knl);
it is never used. There is a Prefer_No_AVX512 bit in cpu_features. But
we don't want to use it here since it will disable AVX512 mathvec on Skylake
server. We need a separate bit to control AVX512 mathvec.
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