Add remaining integer AVX 512f comparison intrinsics

[Daniel-B-Smith]

This is just a draft. I created the PR in order to get CI to run.

[rust-highfive]

r? @gnzlbg

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[Daniel-B-Smith]

This should be ready for review.

[Daniel-B-Smith]

Arguably, all of the other intrinsics should be implemented on top of this intrinsic. My preference would be to declare victory and move on, but I can make the change if you would like.

[Daniel-B-Smith]

It's kind of annoying to have the full implementation duplicated here. When I attempted to call _mm512_mask_cmp_epu64_mask here, the constness of op was not propagated along, so I got compiler errors that the argument needed to be a constant.

[Amanieu]

Are you planning on adding the epi32/epu32 intrinsics as well. Those are also part of AVX512F.

[Daniel-B-Smith]

I'm a little confused by the documentation for the 32 bit comparisons. Most of the 32 bit comparisons read CPUID Flags: AVX512F for AVX-512, KNCNI for KNC, e.g.:

https://software.intel.com/sites/landingpage/IntrinsicsGuide/#expand=727,1063,4909,1062,1062,1063,874,850,779&avx512techs=AVX512F&text=_mm512_cmpeq

The cmplt_epi32 variants have separate AVX 512f and KNCNI documentation entries (which is why those ended up on Alex Crichton's list):

https://software.intel.com/sites/landingpage/IntrinsicsGuide/#expand=727,1063,4909,1062,1062,1063,874,850,779,1029,1029,1030&text=_mm512_cmplt_epi32_mask

I have been reading that documentation as being an implicit AND between AVX512f and Knight's Corner, but it may be an implicit OR (clang implements all of the combined comparisons in the AVX512f header). If it's the latter, we will also need to update the verification tests to accept avx512f for avx512f/kncni (see CI results).

[Amanieu]

I believe the condition is AVX512F OR KNC. I would ignore KNC for now and just gate it on AVX512F only.

[Daniel-B-Smith]

I've added the 32 bit integer comparisons and updated stdarch-verify to accept "avx512f/kncni" intrinsics to be gated by solely "avx512f". Now that I know it is an OR, I will update my list so that I get all of the mixed intrinsics going forward.

[Daniel-B-Smith]

Closing since #866 also contains these changes.