Update prebuilts to go1.7rc1 ab/3043704
toolchain/go sha ffb9ee3a
Change-Id: Id13cc2f426fd6d4e53bde9b50251fb264a647f47
diff --git a/test/atomicload.go b/test/atomicload.go
new file mode 100644
index 0000000..76f1ad4
--- /dev/null
+++ b/test/atomicload.go
@@ -0,0 +1,45 @@
+// run
+
+// Copyright 2016 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.
+
+// Check that we do loads exactly once. The SSA backend
+// once tried to do the load in f twice, once sign extended
+// and once zero extended. This can cause problems in
+// racy code, particularly sync/mutex.
+
+package main
+
+func f(p *byte) bool {
+ x := *p
+ a := int64(int8(x))
+ b := int64(uint8(x))
+ return a == b
+}
+
+func main() {
+ var x byte
+ const N = 1000000
+ c := make(chan struct{})
+ go func() {
+ for i := 0; i < N; i++ {
+ x = 1
+ }
+ c <- struct{}{}
+ }()
+ go func() {
+ for i := 0; i < N; i++ {
+ x = 2
+ }
+ c <- struct{}{}
+ }()
+
+ for i := 0; i < N; i++ {
+ if !f(&x) {
+ panic("non-atomic load!")
+ }
+ }
+ <-c
+ <-c
+}