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Hardware Intrinsics in .NET 8

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  1. Introduction to Hardware Intrinsics in .NET 8: This post provides an in-depth overview of the hardware intrinsics introduced in .NET 8. These intrinsics leverage SIMD (Single Instruction, Multiple Data) support in WebAssembly (Wasm), enabling accelerated core algorithms.

  2. SIMD Support in Wasm: Wasm now provides underlying SIMD support, allowing for accelerated algorithms. .NET exposes this functionality through hardware intrinsics. Developers can take advantage of unique Wasm APIs for more direct Wasm-specific functionality.

  3. New Features in SIMD Support: The introduction of SIMD support in Wasm brings new instructions and hardware functionality. Some examples include bitwise conditional select, EVEX encoding, and AVX-512 instructions. More improvements are expected to be added over time.

  4. Advantages of SIMD Support: SIMD support offers several advantages, such as increased processing power with 512-bit data operations, dedicated masking, and 16 additional SIMD registers. While the number of users benefiting from this functionality is smaller, the improvements for data-heavy workloads are significant.

  5. SIMD Vector Size: To support 512-bit vectors, .NET introduced the Vector128<T> type. While beneficial for large workloads, this can impact smaller workloads negatively. As a result, .NET defaults to reporting Vector128<T> for SIMD support on these platforms.

  6. Contributing and Providing Input: Developers can contribute and provide input by joining discussions on the dotnet/runtime repository on GitHub. They can also participate in API Reviews on the .NET Foundation YouTube channel to provide feedback on new additions to the .NET Libraries.

  7. Legacy SIMD Registers: Legacy SIMD registers were introduced with the introduction of x64 and AVX instructions. x64 provided 8 additional registers, and AVX expanded support to 256-bits, accessible to 32-bit and 64-bit code.

  8. AVX-512: AVX-512, introduced in 2017, expanded SIMD support to 512-bits with registers named from ZMM0 to ZMM31. AVX-512 also introduced new instructions for various operations, such as shifting on 64-bit integers, conversions between unsigned integers and floating-point types, and rearranging vector elements.

  9. Notable New Instructions: Some notable new instructions provided by AVX-512 include support for common operations on 64-bit integers, conversions between unsigned integers and floating-point types, handling floating-point edge cases, rearranging vector elements, and performing two bitwise operations in a single instruction.

  10. Benefits of 64-bit Integer Support: The support for 64-bit integer operations in SIMD instructions eliminates the need for slower or alternative code sequences. Developers can write code that behaves consistently regardless of the underlying data type.

  11. Summary: Hardware intrinsics in .NET 8 leverage SIMD support in Wasm to accelerate core algorithms. These intrinsics provide new instructions and hardware functionality, including expanded SIMD registers, masking support, and advanced operations. SIMD support brings performance improvements to data-heavy workloads and enables more efficient code execution.