Hi,
On Tue, Aug 17, 2021 at 2:33 AM Hendrik Leppkes <h.lepp...@gmail.com> wrote:
> On Tue, Aug 17, 2021 at 8:30 AM Wu Jianhua <jianhua...@intel.com> wrote:
> > Based on IceLake-AVX512 and newer architecture, a broad
> > range of the subsets of AVX512 could be supported.
>
[..]
> > - 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.
>
[After IRC discussion] you want runtime checks for the
variants/combinations-of-subsets that we want to support. Right now, avx512
means skylake, so you may want to rename that flag to "avx512skl", and add
a new runtime flag + check for the icelake subset called "avx512icl". Then
in your implementations, you use the appropriate flag, and code components
can individually choose to use skylake- and/or icelake-optimized ax512
functions.
Ronald
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