cmd/compile/internal/gc: there are no -0 floating-point constants
Fixes #12577.
Change-Id: Id469cd92f5f9436b0ef948ee1a252ed1842bc7aa
Reviewed-on: https://go-review.googlesource.com/16133
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
diff --git a/test/fixedbugs/issue12577.go b/test/fixedbugs/issue12577.go
new file mode 100644
index 0000000..249b4f2
--- /dev/null
+++ b/test/fixedbugs/issue12577.go
@@ -0,0 +1,66 @@
+// run
+
+// 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.
+
+// Issue 12577: Test that there are no -0 floating-point constants.
+
+package main
+
+import "math"
+
+const (
+ z0 = 0.0
+ z1 = -0.0
+ z2 = -z0
+ z3 = -z2
+)
+
+var (
+ x0 float32 = z0
+ x1 float32 = z1
+ x2 float32 = z2
+ x3 float32 = z3
+
+ y0 float64 = z0
+ y1 float64 = z1
+ y2 float64 = z2
+ y3 float64 = z3
+)
+
+func test32(f float32) {
+ if f != 0 || math.Signbit(float64(f)) {
+ println("BUG: got", f, "want 0.0")
+ return
+ }
+}
+
+func test64(f float64) {
+ if f != 0 || math.Signbit(f) {
+ println("BUG: got", f, "want 0.0")
+ return
+ }
+}
+
+func main() {
+ if f := -x0; f != 0 || !math.Signbit(float64(f)) {
+ println("BUG: got", f, "want -0.0")
+ }
+
+ test32(-0.0)
+ test32(x0)
+ test32(x1)
+ test32(x2)
+ test32(x3)
+
+ if f := -y0; f != 0 || !math.Signbit(f) {
+ println("BUG: got", f, "want -0.0")
+ }
+
+ test64(-0.0)
+ test64(y0)
+ test64(y1)
+ test64(y2)
+ test64(y3)
+}
