6. simd — Plan 9 kernels

Part: II · Foundation
Package: github.com/openfluke/welvet/simd
Status: ok — ✅

When

You need the simd foundation package.

Where

import "github.com/openfluke/welvet/simd"

cd 06-simd && source ../env.sh && go run .

Why

CPU peak needs hand-written AVX2/NEON without a silent Go fallback that pretends SIMD ran.

What

amd64/arm64 .s kernels: DotTile, DotI8/U8, DotQ4_0, Saxpy, BitNet helpers, packed f16/bf16/fp8/fp4 dots; amd64 AVX2 DotTileF64 (WireF64); Go fused DotKRow / DotIQRow / DotAffineRow for k/IQ/Affine. SimdEnabled() false → BackendSIMD hard-errors.

Sample output (captured)

10

Live capture from go run ./cmd/runall on local ../../welvet (exit 0).

Source

Copied from the Welvet feature book examples (openfluke.github.io/welvet/examples/06-simd).

package main

import (
	"fmt"

	"github.com/openfluke/welvet/simd"
)

func main() {
	if !simd.SimdEnabled() {
		fmt.Println("SIMD not available on this arch — BackendSIMD must hard-error")
		return
	}
	acc := simd.DotTile([]float32{1, 2, 3, 4}, []float32{1, 1, 1, 1}, 0, 4, 0)
	fmt.Println(acc)
}