Benchmarking dgryski/go-bits versus math/bits

bitsbench_test.go

package bitsbench

import (
	dbits "github.com/dgryski/go-bits"
	"math/bits"
	"testing"
)

// Modelled after https://github.com/golang/go/blob/master/src/math/bits/bits_test.go

// Exported (global) variable serving as input for some
// of the benchmarks to ensure side-effect free calls
// are not optimized away.
var Input uint64 = 0x0218a392cd3d5dbf // deBruijn64

// Exported (global) variable to store function results
// during benchmarking to ensure side-effect free calls
// are not optimized away.
var Output int

func BenchmarkCtzFast(b *testing.B) {
	var s int
	for i := 0; i < b.N; i++ {
		s += int(dbits.Ctz(uint64(Input) << (uint(i) % 64)))
	}
	Output = s
}

func BenchmarkGoMathBitsTrailing(b *testing.B) {
	var s int
	for i := 0; i < b.N; i++ {
		s += bits.TrailingZeros64(uint64(Input) << (uint(i) % 64))
	}
	Output = s
}

func BenchmarkClzFast(b *testing.B) {
	var s int
	for i := 0; i < b.N; i++ {
		s += int(dbits.Clz(uint64(Input) >> (uint(i) % 64)))
	}
	Output = s
}

func BenchmarkGoMathBitsLeading(b *testing.B) {
	var s int
	for i := 0; i < b.N; i++ {
		s += bits.LeadingZeros64(uint64(Input) >> (uint(i) % 64))
	}
	Output = s
}

output

sunny.klair:scratch$ go test -bench=.
goos: darwin
goarch: amd64
pkg: github.com/dgryski/go-bits
BenchmarkCtzFast-4              	1000000000	         2.02 ns/op
BenchmarkGoMathBitsTrailing-4   	2000000000	         1.09 ns/op
BenchmarkClzFast-4              	1000000000	         2.17 ns/op
BenchmarkGoMathBitsLeading-4    	2000000000	         1.15 ns/op
PASS
ok  	workspace/scratch	7.347s