1 files changed, 52 insertions, 0 deletions
diff --git a/test/fixedbugs/issue30977.go b/test/fixedbugs/issue30977.go
new file mode 100644
index 0000000..2ca040d
--- /dev/null
+++ b/test/fixedbugs/issue30977.go
@@ -0,0 +1,52 @@
+// run
+
+// Copyright 2019 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.
+
+// Issue 30977: write barrier call clobbers volatile
+// value when there are multiple uses of the value.
+
+package main
+
+import "runtime"
+
+type T struct {
+	a, b, c, d, e string
+}
+
+//go:noinline
+func g() T {
+	return T{"a", "b", "c", "d", "e"}
+}
+
+//go:noinline
+func f() {
+	// The compiler optimizes this to direct copying
+	// the call result to both globals, with write
+	// barriers. The first write barrier call clobbers
+	// the result of g on stack.
+	X = g()
+	Y = X
+}
+
+var X, Y T
+
+const N = 1000
+
+func main() {
+	// Keep GC running so the write barrier is on.
+	go func() {
+		for {
+			runtime.GC()
+		}
+	}()
+
+	for i := 0; i < N; i++ {
+		runtime.Gosched()
+		f()
+		if X != Y {
+			panic("FAIL")
+		}
+	}
+}