1 files changed, 305 insertions, 0 deletions
diff --git a/test/writebarrier.go b/test/writebarrier.go
new file mode 100644
index 0000000..1b30fa5
--- /dev/null
+++ b/test/writebarrier.go
@@ -0,0 +1,305 @@
+// 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 // no barrier (dead store)
+
+	z := y // no barrier
+	*x = z // ERROR "write barrier"
+}
+
+func f1(x *[]byte, y []byte) {
+	*x = y // no barrier (dead store)
+
+	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 // no barrier (dead store)
+
+	z := y // no barrier
+	*x = z // ERROR "write barrier"
+}
+
+func f2a(x *interface{}, y *interface{}) {
+	*x = *y // no barrier (dead store)
+
+	z := y // no barrier
+	*x = z // ERROR "write barrier"
+}
+
+func f3(x *string, y string) {
+	*x = y // no barrier (dead store)
+
+	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) {
+	case *int: // ERROR "write barrier"
+		return &x
+	}
+	switch y := i.(type) {
+	case **int: // no write barrier here
+		return y
+	}
+	return nil
+}
+
+type T17 struct {
+	f func(*T17)
+}
+
+func f17(x *T17) {
+	// Originally from golang.org/issue/13901, but the hybrid
+	// barrier requires both to have barriers.
+	x.f = f17                      // ERROR "write barrier"
+	x.f = func(y *T17) { *y = *x } // ERROR "write barrier"
+}
+
+type T18 struct {
+	a []int
+	s string
+}
+
+func f18(p *T18, x *[]int) {
+	p.a = p.a[:5]    // no barrier
+	*x = (*x)[0:5]   // no barrier
+	p.a = p.a[3:5]   // ERROR "write barrier"
+	p.a = p.a[1:2:3] // ERROR "write barrier"
+	p.s = p.s[8:9]   // ERROR "write barrier"
+	*x = (*x)[3:5]   // ERROR "write barrier"
+}
+
+func f19(x, y *int, i int) int {
+	// Constructing a temporary slice on the stack should not
+	// require any write barriers. See issue 14263.
+	a := []*int{x, y} // no barrier
+	return *a[i]
+}
+
+func f20(x, y *int, i int) []*int {
+	// ... but if that temporary slice escapes, then the
+	// write barriers are necessary.
+	a := []*int{x, y} // ERROR "write barrier"
+	return a
+}
+
+var x21 *int
+var y21 struct {
+	x *int
+}
+var z21 int
+
+// f21x: Global -> heap pointer updates must have write barriers.
+func f21a(x *int) {
+	x21 = x   // ERROR "write barrier"
+	y21.x = x // ERROR "write barrier"
+}
+
+func f21b(x *int) {
+	x21 = &z21   // ERROR "write barrier"
+	y21.x = &z21 // ERROR "write barrier"
+}
+
+func f21c(x *int) {
+	y21 = struct{ x *int }{x} // ERROR "write barrier"
+}
+
+func f22(x *int) (y *int) {
+	// pointer write on stack should have no write barrier.
+	// this is a case that the frontend failed to eliminate.
+	p := &y
+	*p = x // no barrier
+	return
+}
+
+type T23 struct {
+	p *int
+	a int
+}
+
+var t23 T23
+var i23 int
+
+// f23x: zeroing global needs write barrier for the hybrid barrier.
+func f23a() {
+	t23 = T23{} // ERROR "write barrier"
+}
+
+func f23b() {
+	// also test partial assignments
+	t23 = T23{a: 1} // ERROR "write barrier"
+}
+
+func f23c() {
+	t23 = T23{} // no barrier (dead store)
+	// also test partial assignments
+	t23 = T23{p: &i23} // ERROR "write barrier"
+}
+
+var g int
+
+func f24() **int {
+	p := new(*int)
+	*p = &g // no write barrier here
+	return p
+}
+func f25() []string {
+	return []string{"abc", "def", "ghi"} // no write barrier here
+}
+
+type T26 struct {
+	a, b, c int
+	d, e, f *int
+}
+
+var g26 int
+
+func f26(p *int) *T26 { // see issue 29573
+	return &T26{
+		a: 5,
+		b: 6,
+		c: 7,
+		d: &g26, // no write barrier: global ptr
+		e: nil,  // no write barrier: nil ptr
+		f: p,    // ERROR "write barrier"
+	}
+}
+
+func f27(p *int) []interface{} {
+	return []interface{}{
+		nil,         // no write barrier: zeroed memory, nil ptr
+		(*T26)(nil), // no write barrier: zeroed memory, type ptr & nil ptr
+		&g26,        // no write barrier: zeroed memory, type ptr & global ptr
+		7,           // no write barrier: zeroed memory, type ptr & global ptr
+		p,           // ERROR "write barrier"
+	}
+}
+
+var g28 [256]uint64
+
+func f28() []interface{} {
+	return []interface{}{
+		false,      // no write barrier
+		true,       // no write barrier
+		0,          // no write barrier
+		1,          // no write barrier
+		uint8(127), // no write barrier
+		int8(-4),   // no write barrier
+		&g28[5],    // no write barrier
+	}
+}