}
			u := ir.NewUnaryExpr(n.Pos(), l.BuiltinOp, arg)
			return typecheck(ir.InitExpr(n.Init(), u), top) // typecheckargs can add to old.Init

		case ir.OCOMPLEX, ir.OCOPY, ir.OUNSAFEADD, ir.OUNSAFESLICE, ir.OUNSAFESTRING:
			typecheckargs(n)
			arg1, arg2, ok := needTwoArgs(n)
			if !ok {
				n.SetType(nil)
				return n
			}
			b := ir.NewBinaryExpr(n.Pos(), l.BuiltinOp, arg1, arg2)

		ir.OMIN,
		ir.ONEW,
		ir.OPANIC,
		ir.OPRINT,
		ir.OPRINTLN,
		ir.OREAL,
		ir.ORECOVER,
		ir.ORECOVERFP,
		ir.ORECV,
		ir.OUNSAFEADD,
		ir.OUNSAFESLICE,
		ir.OUNSAFESLICEDATA,
		ir.OUNSAFESTRING,
		ir.OUNSAFESTRINGDATA:
		return true
	}
	return false

	OSEND:             "<-",
	OSUB:              "-",
	OSWITCH:           "switch",
	OUNSAFEADD:        "unsafe.Add",
	OUNSAFESLICE:      "unsafe.Slice",
	OUNSAFESLICEDATA:  "unsafe.SliceData",
	OUNSAFESTRING:     "unsafe.String",
	OUNSAFESTRINGDATA: "unsafe.StringData",
	OXOR:              "^",
}

// GoString returns the Go syntax for the Op, or else its name.
func (o Op) GoString() string {

		n := n.(*ir.BinaryExpr)
		n.X = walkExpr(n.X, init)
		n.Y = walkExpr(n.Y, init)
		return n

	case ir.OUNSAFESLICE:
		n := n.(*ir.BinaryExpr)
		return walkUnsafeSlice(n, init)

	case ir.OUNSAFESTRING:
		n := n.(*ir.BinaryExpr)
		return walkUnsafeString(n, init)

	case ir.OUNSAFESTRINGDATA, ir.OUNSAFESLICEDATA:
		n := n.(*ir.UnaryExpr)
		return walkUnsafeData(n, init)

	case ir.ODOT, ir.ODOTPTR:

		return tcUnsafeAdd(n)

	case ir.OUNSAFESLICE:
		n := n.(*ir.BinaryExpr)
		return tcUnsafeSlice(n)

	case ir.OUNSAFESLICEDATA:
		n := n.(*ir.UnaryExpr)
		return tcUnsafeData(n)

	case ir.OUNSAFESTRING:
		n := n.(*ir.BinaryExpr)
		return tcUnsafeString(n)

	case ir.OUNSAFESTRINGDATA:
		n := n.(*ir.UnaryExpr)
		return tcUnsafeData(n)

	case ir.OITAB:
		n := n.(*ir.UnaryExpr)