if loff != 0 || !types.Identical(typ, l.Type()) {
			dst = ir.NewNameOffsetExpr(base.Pos, l, loff, typ)
		}
		s.append(ir.NewAssignStmt(base.Pos, dst, typecheck.Conv(r, typ)))
		return true

	case ir.ONIL:
		return true

	case ir.OLITERAL:
		if ir.IsZero(r) {
			return true
		}
		staticdata.InitConst(l, loff, r, int(typ.Size()))
		return true

	case ir.OADDR:
		r := r.(*ir.AddrExpr)

		ir.Dump("walk", n)
		base.Fatalf("walkExpr: switch 1 unknown op %+v", n.Op())
		panic("unreachable")

	case ir.OGETG, ir.OGETCALLERPC, ir.OGETCALLERSP:
		return n

	case ir.OTYPE, ir.ONAME, ir.OLITERAL, ir.ONIL, ir.OLINKSYMOFFSET:
		// TODO(mdempsky): Just return n; see discussion on CL 38655.
		// Perhaps refactor to use Node.mayBeShared for these instead.
		// If these return early, make sure to still call

		case ir.OMIN, ir.OMAX:
			// string or float requires runtime call, see (*ssagen.state).minmax method.
			return n.Type().IsString() || n.Type().IsFloat()

		case ir.OLITERAL, ir.ONIL, ir.ONAME, ir.OLINKSYMOFFSET, ir.OMETHEXPR,
			ir.OAND, ir.OANDNOT, ir.OLSH, ir.OOR, ir.ORSH, ir.OXOR, ir.OCOMPLEX, ir.OMAKEFACE,
			ir.OADDR, ir.OBITNOT, ir.ONOT, ir.OPLUS,
			ir.OCAP, ir.OIMAG, ir.OLEN, ir.OREAL,

// and then returns tmp.
func (o *orderState) cheapExpr(n ir.Node) ir.Node {
	if n == nil {
		return nil
	}

	switch n.Op() {
	case ir.ONAME, ir.OLITERAL, ir.ONIL:
		return n
	case ir.OLEN, ir.OCAP:
		n := n.(*ir.UnaryExpr)
		l := o.cheapExpr(n.X)
		if l == n.X {
			return n
		}
		a := ir.Copy(n).(*ir.UnaryExpr)
		a.X = l
		return typecheck.Expr(a)
	}

			}
			c <- struct{}{}
		}()
		runtime.Goexit()
	}()
	// Note: if the defer fails to run, we will get a deadlock here
	<-c
}

func TestGoNil(t *testing.T) {
	output := runTestProg(t, "testprog", "GoNil")
	want := "go of nil func value"
	if !strings.Contains(output, want) {
		t.Fatalf("output:\n%s\n\nwant output containing: %s", output, want)
	}
}

func TestMainGoroutineID(t *testing.T) {

		ir.OANDNOT,
		ir.OBITNOT,
		ir.OCONV,
		ir.OCONVIFACE,
		ir.OCONVNOP,
		ir.ODIV,
		ir.ODOT,
		ir.ODOTTYPE,
		ir.OLITERAL,
		ir.OLSH,
		ir.OMOD,
		ir.OMUL,
		ir.ONEG,
		ir.ONIL,
		ir.OOR,
		ir.OOROR,
		ir.OPAREN,
		ir.OPLUS,
		ir.ORSH,
		ir.OSUB,
		ir.OXOR:
		return false
	}

	// Be conservative.
	return true
}

// expand append(l1, l2...) to

	if cond.Op() == ir.OBYTES2STR && allCaseExprsAreSideEffectFree(sw) {
		cond := cond.(*ir.ConvExpr)
		cond.SetOp(ir.OBYTES2STRTMP)
	}

	cond = walkExpr(cond, sw.PtrInit())
	if cond.Op() != ir.OLITERAL && cond.Op() != ir.ONIL {
		cond = copyExpr(cond, cond.Type(), &sw.Compiled)
	}

	base.Pos = lno

	s := exprSwitch{
		pos:      lno,
		exprname: cond,
	}

	var defaultGoto ir.Node
	var body ir.Nodes