src/simd/archsimd/internal/simd_test/simd_arm64_test.go

// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build goexperiment.simd && arm64

package simd_test

import (
	"simd/archsimd"
	"testing"
)

func TestLookupOrZero(t *testing.T) {
	// Out-of-range indices produce zero lane value.
	x := []uint8{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16}
	indices := []uint8{7, 6, 5, 4, 3, 2, 1, 0, 0xff, 8, 16, 9, 128, 10, 20, 11}
	want := []uint8{8, 7, 6, 5, 4, 3, 2, 1, 0, 9, 0, 10, 0, 11, 0, 12}
	got := make([]uint8, len(x))
	archsimd.LoadUint8x16(x).LookupOrZero(archsimd.LoadUint8x16(indices)).Store(got)
	checkSlices(t, got, want)
}

func TestClMul(t *testing.T) {
	var x = archsimd.LoadUint64x2([]uint64{1, 5})
	var y = archsimd.LoadUint64x2([]uint64{3, 9})

	foo := func(v archsimd.Uint64x2, s []uint64) {
		r := make([]uint64, 2, 2)
		v.Store(r)
		checkSlices[uint64](t, r, s)
	}

	foo(x.CarrylessMultiplyEven(y), []uint64{3, 0})
	foo(x.CarrylessMultiplyEvenOdd(y), []uint64{9, 0})
	foo(x.CarrylessMultiplyOddEven(y), []uint64{15, 0})
	foo(x.CarrylessMultiplyOdd(y), []uint64{45, 0})
	foo(y.CarrylessMultiplyEven(y), []uint64{5, 0})
}

func TestAddSlice(t *testing.T) {
	if !archsimd.ARM64.SVE() {
		t.Skip("no sve")
	}
	testSize := 100
	x := make([]int8, testSize)
	y := make([]int8, testSize)
	for i := 0; i < testSize; i++ {
		x[i] = int8(i)
		y[i] = int8(i + 1)
	}
	res := make([]int8, testSize)
	expected := make([]int8, testSize)
	for i := 0; i < testSize; i++ {
		expected[i] = x[i] + y[i]
	}
	for i := 0; i < testSize; i += 5 {
		// The user can actually choose whatever stride they like.
		// as long as the stride is less than VL, the result
		// won't miss anything.
		p := archsimd.Mask8sFromCount(5)
		xv0, _ := archsimd.LoadInt8sPart(x[i:])
		xv := xv0.Masked(p)
		yv0, _ := archsimd.LoadInt8sPart(y[i:])
		yv := yv0.Masked(p)
		zv := xv.Add(yv).Masked(p)
		zv.Masked(p).StorePart(res[i:])
	}
	for i := range res {
		if res[i] != expected[i] {
			t.Errorf("res[%d] = %d; want %d", i, res[i], expected[i])
		}
	}
}