Benchmarking value vs. pointer receiver for a 56-byte struct

gistfile1.go

package main

import (
	"encoding/binary"
	"testing"
)

var little = binary.LittleEndian

type Segment struct {
	Data    []uint8
}

type Object struct {
	Segment *Segment
	off     int // in bytes
	length  int
	datasz  int // in bytes
	ptrs    int
	typ     uint8
	flags   uint
}

func (p Object) valueListData(i int, sz int) []byte {
	if i < 0 || i >= p.length {
		return nil
	}

	if sz > p.datasz*8 {
		return nil
	}
	off := p.off + i*(p.datasz+p.ptrs*8)
	return p.Segment.Data[off:]
}

func (p *Object) pointerListData(i int, sz int) []byte {
	if i < 0 || i >= p.length {
		return nil
	}

	if sz > p.datasz*8 {
		return nil
	}
	off := p.off + i*(p.datasz+p.ptrs*8)
	return p.Segment.Data[off:]
}

type Int8List Object
type UInt8List Object

func (p Int8List) ValueAt(i int) int8 { return int8(UInt8List(p).ValueAt(i)) }
func (p UInt8List) ValueAt(i int) uint8 {
	if data := Object(p).valueListData(i, 8); data != nil {
		return data[0]
	} else {
		return 0
	}
}

func (p *Int8List) PointerAt(i int) int8 { return int8((*UInt8List)(p).PointerAt(i)) }
func (p *UInt8List) PointerAt(i int) uint8 {
	if data := (*Object)(p).pointerListData(i, 8); data != nil {
		return data[0]
	} else {
		return 0
	}
}

type Struct Object

func (p Struct) ValueGet8(off int) uint8 {
	if off < p.datasz {
		return p.Segment.Data[uint(p.off)+uint(off)]
	} else {
		return 0
	}
}

func (p *Struct) PointerGet8(off int) uint8 {
	if off < p.datasz {
		return p.Segment.Data[uint(p.off)+uint(off)]
	} else {
		return 0
	}
}

func (p Struct) ValueGet64(off int) uint64 {
	if off < p.datasz {
		return little.Uint64(p.Segment.Data[uint(p.off)+uint(off):])
	} else {
		return 0
	}
}

func (p *Struct) PointerGet64(off int) uint64 {
	if off < p.datasz {
		return little.Uint64(p.Segment.Data[uint(p.off)+uint(off):])
	} else {
		return 0
	}
}

var seg = Segment{Data: make([]byte, 1)}

func BenchmarkValueGet8(b *testing.B) {
	var o Struct
	for i := 0; i < b.N; i++ {
		o.ValueGet8(0)
	}
}

func BenchmarkPointerGet8(b *testing.B) {
	var o Struct
	for i := 0; i < b.N; i++ {
		o.PointerGet8(0)
	}
}

func BenchmarkValueGet64(b *testing.B) {
	var o Struct
	for i := 0; i < b.N; i++ {
		o.ValueGet64(0)
	}
}

func BenchmarkPointerGet64(b *testing.B) {
	var o Struct
	for i := 0; i < b.N; i++ {
		o.PointerGet64(0)
	}
}

func BenchmarkValueAt(b *testing.B) {
	var l Int8List
	for i := 0; i < b.N; i++ {
		l.ValueAt(0)
	}
}

func BenchmarkPointerAt(b *testing.B) {
	var l Int8List
	for i := 0; i < b.N; i++ {
		l.PointerAt(0)
	}
}