golang bit flag benchmarks

README.md

this is a simple test of performance for checking if a uint8 (commonly used for bit flags) is non-zero.

• u > 0 is the slowest, averaging 1.14ns/op.
• u != 0 is a little faster, averaging 1.13ns/op.
• casting u to bool is the fastest, averaging 0.98ns/op.

note: the third method is unsafe, and only confirmed to work on linux/amd64, where a non-zero byte is truthy.

const_test.go

package bitflag_test

const (
	Check      uint8 = 0b00010000
	ValueTrue  uint8 = 0b11111111
	ValueFalse uint8 = 0b11101111
)

gt_test.go

package bitflag_test

import (
	"runtime"
	"testing"
)

func BenchmarkGtTrue(b *testing.B) {
	val := ValueTrue
	for i := 0; i < b.N; i++ {
		ok := val&Check > 0
		runtime.KeepAlive(ok)
	}
}

func BenchmarkGtFalse(b *testing.B) {
	val := ValueFalse
	for i := 0; i < b.N; i++ {
		ok := val&Check > 0
		runtime.KeepAlive(ok)
	}
}

ne_test.go

package bitflag_test

import (
	"runtime"
	"testing"
)

func BenchmarkNeTrue(b *testing.B) {
	val := ValueTrue
	for i := 0; i < b.N; i++ {
		ok := val&Check != 0
		runtime.KeepAlive(ok)
	}
}

func BenchmarkNeFalse(b *testing.B) {
	val := ValueFalse
	for i := 0; i < b.N; i++ {
		ok := val&Check != 0
		runtime.KeepAlive(ok)
	}
}

unsafe_test.go

package bitflag_test

import (
	"runtime"
	"testing"
	"unsafe"
)

func BenchmarkUnsafeTrue(b *testing.B) {
	val := ValueTrue
	for i := 0; i < b.N; i++ {
		u := val & Check
		ok := *(*bool)(unsafe.Pointer(&u))
		runtime.KeepAlive(ok)
	}
}

func BenchmarkUnsafeFalse(b *testing.B) {
	val := ValueFalse
	for i := 0; i < b.N; i++ {
		u := val & Check
		ok := *(*bool)(unsafe.Pointer(&u))
		runtime.KeepAlive(ok)
	}
}