On 8/17/2021 12:25 PM, Ronald S. Bultje wrote:
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.
Does it really mean Skylake-X? Afaik the flag checks in cpu.c currently
look for AVX-512 Foundation and ZMM support, so it means Knights Landing
or newer.
What about just making the existing AVX512 flag mean F+VL+DQ+BW, so
Skylake-X (Anything older just lacks useful instructions for
multimedia), and if needed for this new code add a new avx512icl flag
that also looks for something like GFNI.
Ronald
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