[dev.ssa] cmd/compile: implement OPLUS

Change-Id: Iaf282211a717e38b05e5d2661d400d465decad50
Reviewed-on: https://go-review.googlesource.com/14337Reviewed-by: Keith Randall <khr@golang.org>

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

@@ -1599,7 +1599,7 @@ func (s *state) expr(n *Node) *ssa.Value {
 		s.startBlock(bResult)
 		return s.variable(n, Types[TBOOL])
 
-		// unary ops
+	// unary ops
 	case OMINUS:
 		a := s.expr(n.Left)
 		if n.Type.IsComplex() {
@@ -1613,6 +1613,8 @@ func (s *state) expr(n *Node) *ssa.Value {
 	case ONOT, OCOM:
 		a := s.expr(n.Left)
 		return s.newValue1(s.ssaOp(n.Op, n.Type), a.Type, a)
+	case OPLUS:
+		return s.expr(n.Left)
 
 	case OADDR:
 		return s.addr(n.Left)