[Bug target/86393] GCC-8 appears to not detect AVX512 on iMac Pro 2018

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86393

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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             Target|                            |x86_64-*-*
          Component|c                           |target

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think GCC correctly detects that your CPU supports AVX512 (see the -mtune
option it chooses) but those instructions don't always result in faster code,
so I think you need to enable them explicitly.