// Copyright 2011 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.
package runtime_test
import (
"fmt"
"testing"
)
const N = 20
type (
struct24 struct{ a, b, c int64 }
struct32 struct{ a, b, c, d int64 }
struct40 struct{ a, b, c, d, e int64 }
)
func BenchmarkMakeSlice(b *testing.B) {
const length = 2
b.Run("Byte", func(b *testing.B) {
var x []byte
for i := 0; i < b.N; i++ {
x = make([]byte, length, 2*length)
_ = x
}
})
b.Run("Int16", func(b *testing.B) {
var x []int16
for i := 0; i < b.N; i++ {
x = make([]int16, length, 2*length)
_ = x
}
})
b.Run("Int", func(b *testing.B) {
var x []int
for i := 0; i < b.N; i++ {
x = make([]int, length, 2*length)
_ = x
}
})
b.Run("Ptr", func(b *testing.B) {
var x []*byte
for i := 0; i < b.N; i++ {
x = make([]*byte, length, 2*length)
_ = x
}
})
b.Run("Struct", func(b *testing.B) {
b.Run("24", func(b *testing.B) {
var x []struct24
for i := 0; i < b.N; i++ {
x = make([]struct24, length, 2*length)
_ = x
}
})
b.Run("32", func(b *testing.B) {
var x []struct32
for i := 0; i < b.N; i++ {
x = make([]struct32, length, 2*length)
_ = x
}
})
b.Run("40", func(b *testing.B) {
var x []struct40
for i := 0; i < b.N; i++ {
x = make([]struct40, length, 2*length)
_ = x
}
})
})
}
func BenchmarkGrowSlice(b *testing.B) {
b.Run("Byte", func(b *testing.B) {
x := make([]byte, 9)
for i := 0; i < b.N; i++ {
_ = append([]byte(nil), x...)
}
})
b.Run("Int16", func(b *testing.B) {
x := make([]int16, 9)
for i := 0; i < b.N; i++ {
_ = append([]int16(nil), x...)
}
})
b.Run("Int", func(b *testing.B) {
x := make([]int, 9)
for i := 0; i < b.N; i++ {
_ = append([]int(nil), x...)
}
})
b.Run("Ptr", func(b *testing.B) {
x := make([]*byte, 9)
for i := 0; i < b.N; i++ {
_ = append([]*byte(nil), x...)
}
})
b.Run("Struct", func(b *testing.B) {
b.Run("24", func(b *testing.B) {
x := make([]struct24, 9)
for i := 0; i < b.N; i++ {
_ = append([]struct24(nil), x...)
}
})
b.Run("32", func(b *testing.B) {
x := make([]struct32, 9)
for i := 0; i < b.N; i++ {
_ = append([]struct32(nil), x...)
}
})
b.Run("40", func(b *testing.B) {
x := make([]struct40, 9)
for i := 0; i < b.N; i++ {
_ = append([]struct40(nil), x...)
}
})
})
}
var (
SinkIntSlice []int
SinkIntPointerSlice []*int
)
func BenchmarkExtendSlice(b *testing.B) {
var length = 4 // Use a variable to prevent stack allocation of slices.
b.Run("IntSlice", func(b *testing.B) {
s := make([]int, 0, length)
for i := 0; i < b.N; i++ {
s = append(s[:0:length/2], make([]int, length)...)
}
SinkIntSlice = s
})
b.Run("PointerSlice", func(b *testing.B) {
s := make([]*int, 0, length)
for i := 0; i < b.N; i++ {
s = append(s[:0:length/2], make([]*int, length)...)
}
SinkIntPointerSlice = s
})
b.Run("NoGrow", func(b *testing.B) {
s := make([]int, 0, length)
for i := 0; i < b.N; i++ {
s = append(s[:0:length], make([]int, length)...)
}
SinkIntSlice = s
})
}
func BenchmarkAppend(b *testing.B) {
b.StopTimer()
x := make([]int, 0, N)
b.StartTimer()
for i := 0; i < b.N; i++ {
x = x[0:0]
for j := 0; j < N; j++ {
x = append(x, j)
}
}
}
func BenchmarkAppendGrowByte(b *testing.B) {
for i := 0; i < b.N; i++ {
var x []byte
for j := 0; j < 1<<20; j++ {
x = append(x, byte(j))
}
}
}
func BenchmarkAppendGrowString(b *testing.B) {
var s string
for i := 0; i < b.N; i++ {
var x []string
for j := 0; j < 1<<20; j++ {
x = append(x, s)
}
}
}
func BenchmarkAppendSlice(b *testing.B) {
for _, length := range []int{1, 4, 7, 8, 15, 16, 32} {
b.Run(fmt.Sprint(length, "Bytes"), func(b *testing.B) {
x := make([]byte, 0, N)
y := make([]byte, length)
for i := 0; i < b.N; i++ {
x = x[0:0]
x = append(x, y...)
}
})
}
}
var (
blackhole []byte
)
func BenchmarkAppendSliceLarge(b *testing.B) {
for _, length := range []int{1 << 10, 4 << 10, 16 << 10, 64 << 10, 256 << 10, 1024 << 10} {
y := make([]byte, length)
b.Run(fmt.Sprint(length, "Bytes"), func(b *testing.B) {
for i := 0; i < b.N; i++ {
blackhole = nil
blackhole = append(blackhole, y...)
}
})
}
}
func BenchmarkAppendStr(b *testing.B) {
for _, str := range []string{
"1",
"1234",
"12345678",
"1234567890123456",
"12345678901234567890123456789012",
} {
b.Run(fmt.Sprint(len(str), "Bytes"), func(b *testing.B) {
x := make([]byte, 0, N)
for i := 0; i < b.N; i++ {
x = x[0:0]
x = append(x, str...)
}
})
}
}
func BenchmarkAppendSpecialCase(b *testing.B) {
b.StopTimer()
x := make([]int, 0, N)
b.StartTimer()
for i := 0; i < b.N; i++ {
x = x[0:0]
for j := 0; j < N; j++ {
if len(x) < cap(x) {
x = x[:len(x)+1]
x[len(x)-1] = j
} else {
x = append(x, j)
}
}
}
}
var x []int
func f() int {
x[:1][0] = 3
return 2
}
func TestSideEffectOrder(t *testing.T) {
x = make([]int, 0, 10)
x = append(x, 1, f())
if x[0] != 1 || x[1] != 2 {
t.Error("append failed: ", x[0], x[1])
}
}
func TestAppendOverlap(t *testing.T) {
x := []byte("1234")
x = append(x[1:], x...) // p > q in runtime·appendslice.
got := string(x)
want := "2341234"
if got != want {
t.Errorf("overlap failed: got %q want %q", got, want)
}
}
func BenchmarkCopy(b *testing.B) {
for _, l := range []int{1, 2, 4, 8, 12, 16, 32, 128, 1024} {
buf := make([]byte, 4096)
b.Run(fmt.Sprint(l, "Byte"), func(b *testing.B) {
s := make([]byte, l)
var n int
for i := 0; i < b.N; i++ {
n = copy(buf, s)
}
b.SetBytes(int64(n))
})
b.Run(fmt.Sprint(l, "String"), func(b *testing.B) {
s := string(make([]byte, l))
var n int
for i := 0; i < b.N; i++ {
n = copy(buf, s)
}
b.SetBytes(int64(n))
})
}
}
var (
sByte []byte
s1Ptr []uintptr
s2Ptr [][2]uintptr
s3Ptr [][3]uintptr
s4Ptr [][4]uintptr
)
// BenchmarkAppendInPlace tests the performance of append
// when the result is being written back to the same slice.
// In order for the in-place optimization to occur,
// the slice must be referred to by address;
// using a global is an easy way to trigger that.
// We test the "grow" and "no grow" paths separately,
// but not the "normal" (occasionally grow) path,
// because it is a blend of the other two.
// We use small numbers and small sizes in an attempt
// to avoid benchmarking memory allocation and copying.
// We use scalars instead of pointers in an attempt
// to avoid benchmarking the write barriers.
// We benchmark four common sizes (byte, pointer, string/interface, slice),
// and one larger size.
func BenchmarkAppendInPlace(b *testing.B) {
b.Run("NoGrow", func(b *testing.B) {
const C = 128
b.Run("Byte", func(b *testing.B) {
for i := 0; i < b.N; i++ {
sByte = make([]byte, C)
for j := 0; j < C; j++ {
sByte = append(sByte, 0x77)
}
}
})
b.Run("1Ptr", func(b *testing.B) {
for i := 0; i < b.N; i++ {
s1Ptr = make([]uintptr, C)
for j := 0; j < C; j++ {
s1Ptr = append(s1Ptr, 0x77)
}
}
})
b.Run("2Ptr", func(b *testing.B) {
for i := 0; i < b.N; i++ {
s2Ptr = make([][2]uintptr, C)
for j := 0; j < C; j++ {
s2Ptr = append(s2Ptr, [2]uintptr{0x77, 0x88})
}
}
})
b.Run("3Ptr", func(b *testing.B) {
for i := 0; i < b.N; i++ {
s3Ptr = make([][3]uintptr, C)
for j := 0; j < C; j++ {
s3Ptr = append(s3Ptr, [3]uintptr{0x77, 0x88, 0x99})
}
}
})
b.Run("4Ptr", func(b *testing.B) {
for i := 0; i < b.N; i++ {
s4Ptr = make([][4]uintptr, C)
for j := 0; j < C; j++ {
s4Ptr = append(s4Ptr, [4]uintptr{0x77, 0x88, 0x99, 0xAA})
}
}
})
})
b.Run("Grow", func(b *testing.B) {
const C = 5
b.Run("Byte", func(b *testing.B) {
for i := 0; i < b.N; i++ {
sByte = make([]byte, 0)
for j := 0; j < C; j++ {
sByte = append(sByte, 0x77)
sByte = sByte[:cap(sByte)]
}
}
})
b.Run("1Ptr", func(b *testing.B) {
for i := 0; i < b.N; i++ {
s1Ptr = make([]uintptr, 0)
for j := 0; j < C; j++ {
s1Ptr = append(s1Ptr, 0x77)
s1Ptr = s1Ptr[:cap(s1Ptr)]
}
}
})
b.Run("2Ptr", func(b *testing.B) {
for i := 0; i < b.N; i++ {
s2Ptr = make([][2]uintptr, 0)
for j := 0; j < C; j++ {
s2Ptr = append(s2Ptr, [2]uintptr{0x77, 0x88})
s2Ptr = s2Ptr[:cap(s2Ptr)]
}
}
})
b.Run("3Ptr", func(b *testing.B) {
for i := 0; i < b.N; i++ {
s3Ptr = make([][3]uintptr, 0)
for j := 0; j < C; j++ {
s3Ptr = append(s3Ptr, [3]uintptr{0x77, 0x88, 0x99})
s3Ptr = s3Ptr[:cap(s3Ptr)]
}
}
})
b.Run("4Ptr", func(b *testing.B) {
for i := 0; i < b.N; i++ {
s4Ptr = make([][4]uintptr, 0)
for j := 0; j < C; j++ {
s4Ptr = append(s4Ptr, [4]uintptr{0x77, 0x88, 0x99, 0xAA})
s4Ptr = s4Ptr[:cap(s4Ptr)]
}
}
})
})
}
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