func fieldReduceOnce(a uint16) fieldElement {
	x := a - q
	// If x underflowed, then x >= 2¹⁶ - q > 2¹⁵, so the top bit is set.
	x += (x >> 15) * q
	return fieldElement(x)
}

func fieldAdd(a, b fieldElement) fieldElement {
	x := uint16(a + b)
	return fieldReduceOnce(x)
}

func fieldSub(a, b fieldElement) fieldElement {
	x := uint16(a - b + q)
	return fieldReduceOnce(x)
}

const (

		if got != exp {
			t.Fatalf("reduce(%d) = %d, expected %d", a, got, exp)
		}
	}
}

func TestFieldAdd(t *testing.T) {
	for a := fieldElement(0); a < q; a++ {
		for b := fieldElement(0); b < q; b++ {
			got := fieldAdd(a, b)
			exp := (a + b) % q
			if got != exp {
				t.Fatalf("%d + %d = %d, expected %d", a, b, got, exp)
			}
		}
	}
}

func TestFieldSub(t *testing.T) {
	for a := fieldElement(0); a < q; a++ {

		}
	default:
		field.ValueOf = func(ctx context.Context, v reflect.Value) (interface{}, bool) {
			v = reflect.Indirect(v)
			for _, fieldIdx := range field.StructField.Index {
				if fieldIdx >= 0 {
					v = v.Field(fieldIdx)
				} else {
					v = v.Field(-fieldIdx - 1)

					if !v.IsNil() {
						v = v.Elem()
					} else {
						return nil, true
					}
				}
			}

// callee args space for its use.
func (s *State) UseArgs(n int64) {
	if s.maxarg < n {
		s.maxarg = n
	}
}

// fieldIdx finds the index of the field referred to by the ODOT node n.
func fieldIdx(n *ir.SelectorExpr) int {
	t := n.X.Type()
	if !t.IsStruct() {
		panic("ODOT's LHS is not a struct")
	}

	for i, f := range t.Fields() {
		if f.Sym == n.Sel {