1 files changed, 78 insertions, 0 deletions
diff --git a/test/fixedbugs/bug484.go b/test/fixedbugs/bug484.go
new file mode 100644
index 0000000..bd4fa51
--- /dev/null
+++ b/test/fixedbugs/bug484.go
@@ -0,0 +1,78 @@
+// run
+
+// Copyright 2014 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.
+
+// The liveness code used to say that, in func g, s was live
+// starting at its declaration, because it appears to have its
+// address taken by the closure (different s, but the parser
+// gets slightly confused, a separate bug). The liveness analysis
+// saw s as having its address taken but the register optimizer
+// did not. This mismatch meant that s would be marked live
+// (and therefore initialized) at the call to f, but the register optimizer
+// would optimize away the initialization of s before f, causing the
+// garbage collector to use unused data.
+// The register optimizer has been changed to respect the
+// same "address taken" flag that the liveness analysis uses,
+// even if it cannot see any address being taken in the actual
+// machine code. This is conservative but keeps the two consistent,
+// which is the most important thing.
+
+package main
+
+import "runtime"
+
+//go:noinline
+func f() interface{} {
+	runtime.GC()
+	return nil
+}
+
+//go:noinline
+func g() {
+	var s interface{}
+	_ = func() {
+		s := f()
+		_ = s
+	}
+	s = f()
+	useiface(s)
+	useiface(s)
+}
+
+//go:noinline
+func useiface(x interface{}) {
+}
+
+//go:noinline
+func h() {
+	var x [16]uintptr
+	for i := range x {
+		x[i] = 1
+	}
+
+	useint(x[0])
+	useint(x[1])
+	useint(x[2])
+	useint(x[3])
+}
+
+//go:noinline
+func useint(x uintptr) {
+}
+
+func main() {
+	// scribble non-zero values on stack
+	h()
+	// call function that used to let the garbage collector
+	// see uninitialized stack values; it will see the
+	// nonzero values.
+	g()
+}
+
+func big(x int) {
+	if x >= 0 {
+		big(x - 1)
+	}
+}