64-bit integer math bugs

R=r
DELTA=46  (46 added, 0 deleted, 0 changed)
OCL=29569
CL=29614
diff --git a/test/bugs/bug156.go b/test/bugs/bug156.go
new file mode 100644
index 0000000..0b77a72
--- /dev/null
+++ b/test/bugs/bug156.go
@@ -0,0 +1,21 @@
+// $G $D/$F.go || echo BUG: bug156
+
+// Copyright 2009 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.
+
+package main
+
+func f(a int64) int64 {
+	const b int64 = 0;
+	n := a &^ b;
+	return n;
+}
+
+func main() {
+	f(1)
+}
+
+/*
+bug156.go:7: constant 18446744073709551615 overflows int64
+*/