[FFmpeg-devel] [PATCH] configure: set IceLake-AVX512 as the minimum baseline

[Hendrik Leppkes]

On Tue, Aug 17, 2021 at 8:30 AM Wu Jianhua <jianhua.wu at intel.com> wrote:
>
> Based on IceLake-AVX512 and newer architecture, a broad
> range of the subsets of AVX512 could be supported.
>
> Signed-off-by: Wu Jianhua <jianhua.wu at intel.com>
> ---
>  configure | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/configure b/configure
> index 94b30afe74..04caa25736 100755
> --- a/configure
> +++ b/configure
> @@ -6057,7 +6057,9 @@ EOF
>              elf*) enabled debug && append X86ASMFLAGS $x86asm_debug ;;
>          esac
>
> -        enabled avx512 && check_x86asm avx512_external "vmovdqa32 [eax]{k1}{z}, zmm0"
> +        # Only IceLake and newer architectures could enable AVX512
> +        # F/CD/BW/DQ/VL/VNNI/IFMA/VBMI/VBMI2/VPOPCNTDQ/BITALG/GFNI/VAES/VPCLMULQDQ
> +        enabled avx512 && check_x86asm avx512_external "vpdpwssds zmm31{k1}{z}, zmm29, zmm28"
>          enabled avx2   && check_x86asm avx2_external   "vextracti128 xmm0, ymm0, 0"
>          enabled xop    && check_x86asm xop_external    "vpmacsdd xmm0, xmm1, xmm2, xmm3"
>          enabled fma4   && check_x86asm fma4_external   "vfmaddps ymm0, ymm1, ymm2, ymm3"

Note that you are just checking the functionality of the assembler
here, not having a runtime impact.
What you would likely want is to update avutil/x86/cpu.c as well to
only enable the AVX512 flag on those CPUs.

- Hendrik