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// 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 "testing"
const N = 20
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 benchmarkAppendBytes(b *testing.B, length int) {
b.StopTimer()
x := make([]byte, 0, N)
y := make([]byte, length)
b.StartTimer()
for i := 0; i < b.N; i++ {
x = x[0:0]
x = append(x, y...)
}
}
func BenchmarkAppend1Byte(b *testing.B) {
benchmarkAppendBytes(b, 1)
}
func BenchmarkAppend4Bytes(b *testing.B) {
benchmarkAppendBytes(b, 4)
}
func BenchmarkAppend8Bytes(b *testing.B) {
benchmarkAppendBytes(b, 8)
}
func BenchmarkAppend16Bytes(b *testing.B) {
benchmarkAppendBytes(b, 16)
}
func BenchmarkAppend32Bytes(b *testing.B) {
benchmarkAppendBytes(b, 32)
}
func benchmarkAppendStr(b *testing.B, str string) {
b.StopTimer()
x := make([]byte, 0, N)
b.StartTimer()
for i := 0; i < b.N; i++ {
x = x[0:0]
x = append(x, str...)
}
}
func BenchmarkAppendStr1Byte(b *testing.B) {
benchmarkAppendStr(b, "1")
}
func BenchmarkAppendStr4Bytes(b *testing.B) {
benchmarkAppendStr(b, "1234")
}
func BenchmarkAppendStr8Bytes(b *testing.B) {
benchmarkAppendStr(b, "12345678")
}
func BenchmarkAppendStr16Bytes(b *testing.B) {
benchmarkAppendStr(b, "1234567890123456")
}
func BenchmarkAppendStr32Bytes(b *testing.B) {
benchmarkAppendStr(b, "12345678901234567890123456789012")
}
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)
}
}
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