1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
|
// errorcheck -0 -l -d=wb
// Copyright 2015 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.
// Test where write barriers are and are not emitted.
package p
import "unsafe"
func f(x **byte, y *byte) {
*x = y // ERROR "write barrier"
z := y // no barrier
*x = z // ERROR "write barrier"
}
func f1(x *[]byte, y []byte) {
*x = y // ERROR "write barrier"
z := y // no barrier
*x = z // ERROR "write barrier"
}
func f1a(x *[]byte, y *[]byte) {
*x = *y // ERROR "write barrier"
z := *y // no barrier
*x = z // ERROR "write barrier"
}
func f2(x *interface{}, y interface{}) {
*x = y // ERROR "write barrier"
z := y // no barrier
*x = z // ERROR "write barrier"
}
func f2a(x *interface{}, y *interface{}) {
*x = *y // ERROR "write barrier"
z := y // no barrier
*x = z // ERROR "write barrier"
}
func f3(x *string, y string) {
*x = y // ERROR "write barrier"
z := y // no barrier
*x = z // ERROR "write barrier"
}
func f3a(x *string, y *string) {
*x = *y // ERROR "write barrier"
z := *y // no barrier
*x = z // ERROR "write barrier"
}
func f4(x *[2]string, y [2]string) {
*x = y // ERROR "write barrier"
z := y // no barrier
*x = z // ERROR "write barrier"
}
func f4a(x *[2]string, y *[2]string) {
*x = *y // ERROR "write barrier"
z := *y // no barrier
*x = z // ERROR "write barrier"
}
type T struct {
X *int
Y int
M map[int]int
}
func f5(t, u *T) {
t.X = &u.Y // ERROR "write barrier"
}
func f6(t *T) {
t.M = map[int]int{1: 2} // ERROR "write barrier"
}
func f7(x, y *int) []*int {
var z [3]*int
i := 0
z[i] = x // ERROR "write barrier"
i++
z[i] = y // ERROR "write barrier"
i++
return z[:i]
}
func f9(x *interface{}, v *byte) {
*x = v // ERROR "write barrier"
}
func f10(x *byte, f func(interface{})) {
f(x)
}
func f11(x *unsafe.Pointer, y unsafe.Pointer) {
*x = unsafe.Pointer(uintptr(y) + 1) // ERROR "write barrier"
}
func f12(x []*int, y *int) []*int {
// write barrier for storing y in x's underlying array
x = append(x, y) // ERROR "write barrier"
return x
}
func f12a(x []int, y int) []int {
// y not a pointer, so no write barriers in this function
x = append(x, y)
return x
}
func f13(x []int, y *[]int) {
*y = append(x, 1) // ERROR "write barrier"
}
func f14(y *[]int) {
*y = append(*y, 1) // ERROR "write barrier"
}
type T1 struct {
X *int
}
func f15(x []T1, y T1) []T1 {
return append(x, y) // ERROR "write barrier"
}
type T8 struct {
X [8]*int
}
func f16(x []T8, y T8) []T8 {
return append(x, y) // ERROR "write barrier"
}
func t1(i interface{}) **int {
// From issue 14306, make sure we have write barriers in a type switch
// where the assigned variable escapes.
switch x := i.(type) { // ERROR "write barrier"
case *int:
return &x
}
switch y := i.(type) { // no write barrier here
case **int:
return y
}
return nil
}
|
