[dev.ssa] cmd/compile/internal/ssa: treat -0.0 literal as 0.0

This matches existing behavior, see issue #2196

Change-Id: Ifa9359b7c821115389f337a57de355c5ec23be8f
Reviewed-on: https://go-review.googlesource.com/14261Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/gc/ssa.go

@@ -1254,9 +1254,11 @@ func (s *state) expr(n *Node) *ssa.Value {
 			f := n.Val().U.(*Mpflt)
 			switch n.Type.Size() {
 			case 4:
-				return s.constFloat32(n.Type, mpgetflt32(f))
+				// -0.0 literals need to be treated as if they were 0.0, adding 0.0 here
+				// accomplishes this while not affecting other values.
+				return s.constFloat32(n.Type, mpgetflt32(f)+0.0)
 			case 8:
-				return s.constFloat64(n.Type, mpgetflt(f))
+				return s.constFloat64(n.Type, mpgetflt(f)+0.0)
 			default:
 				s.Fatalf("bad float size %d", n.Type.Size())
 				return nil
@@ -1269,16 +1271,18 @@ func (s *state) expr(n *Node) *ssa.Value {
 			case 8:
 				{
 					pt := Types[TFLOAT32]
+					// -0.0 literals need to be treated as if they were 0.0, adding 0.0 here
+					// accomplishes this while not affecting other values.
 					return s.newValue2(ssa.OpComplexMake, n.Type,
-						s.constFloat32(pt, mpgetflt32(r)),
-						s.constFloat32(pt, mpgetflt32(i)))
+						s.constFloat32(pt, mpgetflt32(r)+0.0),
+						s.constFloat32(pt, mpgetflt32(i)+0.0))
 				}
 			case 16:
 				{
 					pt := Types[TFLOAT64]
 					return s.newValue2(ssa.OpComplexMake, n.Type,
-						s.constFloat64(pt, mpgetflt(r)),
-						s.constFloat64(pt, mpgetflt(i)))
+						s.constFloat64(pt, mpgetflt(r)+0.0),
+						s.constFloat64(pt, mpgetflt(i)+0.0))
 				}
 			default:
 				s.Fatalf("bad float size %d", n.Type.Size())

test/run.go

@@ -636,13 +636,7 @@ func (t *test) run() {
 		}
 
 	case "run":
-		useTmp = false
-		switch t.gofile {
-		case "bug434.go":
-			// TODO fix this failure
-		default:
-			ssaMain = true
-		}
+		ssaMain = true
 		out, err := runcmd(append([]string{"go", "run", t.goFileName()}, args...)...)
 		if err != nil {
 			t.err = err