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[Arm64] ASIMD Polynomial Multiply Long #35143

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#36853
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[Arm64] ASIMD Polynomial Multiply Long#35143
#36853
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echesakov
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api-approvedAPI was approved in API review, it can be implementedarch-arm64area-System.Runtime.Intrinsics
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5.0.0

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@echesakov
echesakov
opened on Apr 17, 2020

The following are omitted in #32512

class AdvSimd
{
        /// <summary>
        /// poly16x8_t vmull_p8 (poly8x8_t a, poly8x8_t b)
        ///   A32: VMULL.P8 Qd, Dn, Dm
        ///   A64: PMULL Vd.16B, Vn.8B, Vm.8B
        /// </summary>
        public static Vector128<sbyte> PolynomialMultiplyWideningLower(Vector64<sbyte> left, Vector64<sbyte> right);

        /// <summary>
        /// poly16x8_t vmull_p8 (poly8x8_t a, poly8x8_t b)
        ///   A32: VMULL.P8 Qd, Dn, Dm
        ///   A64: PMULL Vd.16B, Vn.8B, Vm.8B
        /// </summary>
        public static Vector128<byte> PolynomialMultiplyWideningLower(Vector64<byte> left, Vector64<byte> right);

        /// <summary>
        /// poly16x8_t vmull_high_p8 (poly8x16_t a, poly8x16_t b)
        ///   A32: VMULL.P8 Qd, Dn+1, Dm+1
        ///   A64: PMULL2 Vd.16B, Vn.16B, Vm.16B
        /// </summary>
        public static Vector128<sbyte> PolynomialMultiplyWideningUpper(Vector128<sbyte> left, Vector128<sbyte> right);

        /// <summary>
        /// poly16x8_t vmull_high_p8 (poly8x16_t a, poly8x16_t b)
        ///   A32: VMULL.P8 Qd, Dn+1, Dm+1
        ///   A64: PMULL2 Vd.16B, Vn.16B, Vm.16B
        /// </summary>
        public static Vector128<byte> PolynomialMultiplyWideningUpper(Vector128<byte> left, Vector128<byte> right);
}

class Aes
{
        /// <summary>
        /// poly128_t vmull_p64 (poly64_t a, poly64_t b)
        ///   A32: VMULL.P8 Qd, Dn, Dm
        ///   A64: PMULL Vd.1Q, Vn.1D, Vm.1D
        /// </summary>
        public static Vector128<long> PolynomialMultiplyWideningLower(Vector64<long> left, Vector64<long> right);

        /// <summary>
        /// poly128_t vmull_p64 (poly64_t a, poly64_t b)
        ///   A32: VMULL.P8 Qd, Dn, Dm
        ///   A64: PMULL Vd.1Q, Vn.1D, Vm.1D
        /// </summary>
        public static Vector128<ulong> PolynomialMultiplyWideningLower(Vector64<ulong> left, Vector64<ulong> right);

        /// <summary>
        /// poly128_t vmull_high_p64 (poly64x2_t a, poly64x2_t b)
        ///   A32: VMULL.P8 Qd, Dn+1, Dm+1
        ///   A64: PMULL2 Vd.1Q, Vn.2D, Vm.2D
        /// </summary>
        public static Vector128<long> PolynomialMultiplyWideningUpper(Vector128<long> left, Vector128<long> right);

        /// <summary>
        /// poly128_t vmull_high_p64 (poly64x2_t a, poly64x2_t b)
        ///   A32: VMULL.P8 Qd, Dn+1, Dm+1
        ///   A64: PMULL2 Vd.1Q, Vn.2D, Vm.2D
        /// </summary>
        public static Vector128<ulong> PolynomialMultiplyWideningUpper(Vector128<ulong> left, Vector128<ulong> right);
}

There is also encoding PMULL Vd.1Q, Vn.1D, Vm.1D and PMULL2 Vd.1Q, Vn.2D, Vm.2D which

is only allocated in an implementation that includes the Cryptographic
Extension, and is otherwise RESERVED.

I wonder whether we want to expose these at all in .NET 5.0 - since they don't belong to ASIMD ISA?

cc @CarolEidt @TamarChristinaArm @tannergooding

Activity

  1. echesakov
    added
    api-ready-for-review
    arch-arm64
    area-System.Runtime.Intrinsics
    on Apr 17, 2020
  3. Dotnet-GitSync-Bot
    added
    untriagedNew issue has not been triaged by the area owner
    on Apr 17, 2020

  4. TamarChristinaArm commented on Apr 20, 2020

    @TamarChristinaArm
    TamarChristinaArm
    on Apr 20, 2020
    Contributor

    hmm did we get PMUL itself already?

  5. echesakov commented on Apr 20, 2020

    @echesakov
    echesakov
    on Apr 20, 2020
    ContributorAuthor

    hmm did we get PMUL itself already?

    Yes, I implemented it in #33889

  6. TamarChristinaArm commented on Apr 20, 2020

    @TamarChristinaArm
    TamarChristinaArm
    on Apr 20, 2020
    Contributor

    I wonder whether we want to expose these at all in .NET 5.0 - since they don't belong to ASIMD ISA?

    If you do, won't that require the rest of the AES instructions as well? Since they use the same feature bit.

  7. echesakov commented on Apr 20, 2020

    @echesakov
    echesakov
    on Apr 20, 2020
    ContributorAuthor

    If you do, won't that require the rest of the AES instructions as well? Since they use the same feature bit.

    Good point - I think we have got all AES, SHA1 and SHA256 implemented.

    Arm Architecture Reference Manual (A2.3 The Armv8 Cryptographic Extension) talks about Armv8 Cryptographic Extension and the features ARMv8.0-AES and ARMv8.0-SHA:

    The Armv8 Cryptographic Extension provides instructions for the acceleration of encryption and decryption, and
    includes the following features:
    • ARMv8.0-AES, which includes AESD and AESE instructions.
    • ARMv8.0-SHA, which includes the SHA1* and SHA256* instructions.
    The presence of the Cryptographic Extension in an implementation is subject to export license controls. The
    Cryptographic Extension is an extension of the SIMD support and operates on the vector register file.
    The Cryptographic Extension also provides multiply instructions that operate on long polynomials

    I wonder if this means that a full path, for example, to intrinsic Sha1_FixedRotate should include CryptographicExtension class somewhere in the middle (i.e. be System.Runtime.Intrinsics.Arm.CryptographicExtension.Sha1.FixedRotate) since Sha1 is a subset of instructions (a feature) provided by Cryptographic Extension.

    Is my understanding correct, that PMULL instruction that operates on two 64-bit polynomials is going to be a part of the CryptographicExtension but neither Aes nor Sha features?

  8. TamarChristinaArm commented on Apr 21, 2020

    @TamarChristinaArm
    TamarChristinaArm
    on Apr 21, 2020
    Contributor

    Unfortunately the crypto landscape is quite complicated... And there seems to be a discrepancy between the descriptions of Armv8.0-A and Armv8.2-A+. I've asked internally for someclarification.

    Is my understanding correct, that PMULL instruction that operates on two 64-bit polynomials is going to be a part of the CryptographicExtension but neither Aes nor Sha features?

    No, CryptographicExtension is just a made up term, it's not an actual extension. In that it has no feature bits of it's own. CryptographicExtension for Armv8.0-A contains AES and SHA1 but from Armv8.2-A+ the class is much bigger.

    If you look at the identification register in ID_AA64ISAR0_EL1 (section D13.2.53) you'll see that PMULL crypto instructions are defined as an optional part of AES in Armv8 (page D13-3099 of the E release of the Arm ARM).

    So it belongs as part of AES. I'll reply more once I get a response on the ambiguity between Armv8.0-A and Arm8.2-A.

  9. echesakov commented on Apr 21, 2020

    @echesakov
    echesakov
    on Apr 21, 2020
    ContributorAuthor

    @TamarChristinaArm Thanks for the clarification - I will update the proposal to have PMULL on two 64-bit polynomials under Aes.

  10. TamarChristinaArm commented on Apr 27, 2020

    @TamarChristinaArm
    TamarChristinaArm
    on Apr 27, 2020
    Contributor

    @echesakovMSFT It's been confirmed to me that indeed we expect people to implement AES and PMULL together. At some point this will be updated in the Arm ARM, but this also matches with llvm and gcc do.

  11. echesakov commented on Apr 27, 2020

    @echesakov
    echesakov
    on Apr 27, 2020
    ContributorAuthor

    @TamarChristinaArm Thanks for following up on this!

  12. echesakov
    self-assigned this
    on Apr 27, 2020

  13. echesakov commented on May 1, 2020

    @echesakov
    echesakov
    on May 1, 2020
    ContributorAuthor

    Updated the proposal to include PMULL Vd.1Q, Vn.1D, Vm.1D and PMULL2 Vd.1Q, Vn.2D, Vm.2D under Aes class

    I could not think about a better way of mapping poly128_t to .NET type system other than Vector128<long> or Vector128<ulong>

  14. echesakov
    removed
    untriagedNew issue has not been triaged by the area owner
    on May 1, 2020
  15. JulieLeeMSFT
    added this to the 5.0 milestone on May 18, 2020
  16. terrajobst
    added
    api-approvedAPI was approved in API review, it can be implemented
    and removed
    api-ready-for-review
    on May 19, 2020

  17. terrajobst commented on May 19, 2020

    @terrajobst
    terrajobst
    on May 19, 2020
    Contributor
    • Looks good as proposed
    namespace System.Runtime.Intrinsics.Arm
{
    partial class AdvSimd
    {
        public static Vector128<sbyte> PolynomialMultiplyWideningLower(Vector64<sbyte>  left, Vector64<sbyte>  right);
        public static Vector128<byte>  PolynomialMultiplyWideningLower(Vector64<byte>   left, Vector64<byte>   right);
        public static Vector128<sbyte> PolynomialMultiplyWideningUpper(Vector128<sbyte> left, Vector128<sbyte> right);
        public static Vector128<byte>  PolynomialMultiplyWideningUpper(Vector128<byte>  left, Vector128<byte>  right);
    }
    partial class Aes
    {
        public static Vector128<long>  PolynomialMultiplyWideningLower(Vector64<long>   left, Vector64<long>   right);
        public static Vector128<ulong> PolynomialMultiplyWideningLower(Vector64<ulong>  left, Vector64<ulong>  right);
        public static Vector128<long>  PolynomialMultiplyWideningUpper(Vector128<long>  left, Vector128<long>  right);
        public static Vector128<ulong> PolynomialMultiplyWideningUpper(Vector128<ulong> left, Vector128<ulong> right);
    }
}
  18. echesakov
    closed this as completedin #36853on May 22, 2020
  19. ghost locked as resolved and limited conversation to collaborators on Dec 9, 2020
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