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

[jakub at gcc dot gnu.org]

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

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |jakub at gcc dot gnu.org

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Mikael Slevinsky from comment #2)
> If I call it `testavx512.c`, then AVX512-like assembly is created, but it
> errors when trying to create an executable:
> 
> dhcp-10-45-0-78:FastTransforms mikael$ gcc-8 -S -O3 -mavx512f testavx512.c
> -o testavx512.s
> dhcp-10-45-0-78:FastTransforms mikael$ gcc-8 -O3 -mavx512f testavx512.c -o
> testavx512
> /var/folders/dy/wbvgp8656tg6kwtz8sx_9z_m0000gn/T//cchgQrNi.s:45:2: error:
> instruction requires: AVX-512 ISA
>         vmovupd 0(%r13), %zmm0
>         ^
> /var/folders/dy/wbvgp8656tg6kwtz8sx_9z_m0000gn/T//cchgQrNi.s:46:2: error:
> instruction requires: AVX-512 ISA
>         vaddpd  (%r12), %zmm0, %zmm0
>         ^
> /var/folders/dy/wbvgp8656tg6kwtz8sx_9z_m0000gn/T//cchgQrNi.s:47:2: error:
> instruction requires: AVX-512 ISA
>         vmovupd %zmm0, (%rax)
>         ^

Does your assembler support AVX512F at all?  And if it does, does it require
some magic options to be passed to the assembler so that it is supported?
Usually on x86_64 assemblers accept all ISAs by default without special magic
options, but perhaps the assembler on darwin violates this.