Upgrading Vector256/512 Shuffle() with VBMI support

[DeepakRajendrakumaran]

This change does the following
1: Accelerates Vector512.Shuffle() using AVX512VBMI(permb)
2. Accelerates Vector256.Shuffle() using AVX512VBMI_VL
3. Accelerates Vector256.Shuffle() using AVX512BW_VL
@dotnet/avx512-contrib

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Issue Details

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Upgrading Vector256/512 Shuffle() with VBMI support

Author:	DeepakRajendrakumaran
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[DeepakRajendrakumaran]

I can't figure out if the CI fails are known issues or build specific Looks like infrastructure from this

[tannergooding]

There's currently an infrastructure issue causing a large number of CI machine timeouts. It's likely not related to your PR.

[DeepakRajendrakumaran]

There's currently an infrastructure issue causing a large number of CI machine timeouts. It's likely not related to your PR.

Please let me know you there is anything else to be done on this to be merged.

[tannergooding]

There's potentially a missing "todo" here to handle this using pshufb if we don't cross lanes and VBMI is not available.

I don't think it needs to be handled as part of this PR (or even for .NET 8 necessarily) since that scenario should only be limited to pre-cannon lake (and therefore first generation AVX-512 hardware). But, since it should just be refactoring the logic under the if (simdSize == 32) path to be shared; its probably worth having still.

[tannergooding]

CC. @dotnet/jit-contrib, @dotnet/avx512-contrib for secondary sign-off.