ed).
<li> <code>mpn_divrem_2</code> could usefully accept unnormalized divisors and
     shift the dividend on-the-fly, since this should cost nothing on
     superscalar processors and avoid the need for temporary copying in
     <code>mpn_tdiv_qr</code>.
<li> <code>mpf_sqrt</code>: If r!=u, and if u doesn't need to be padded with
     zeros, then there's no need for the tp temporary.
<li> <code>mpq_cmp_ui</code> could form the <code>num1*den2</code> and
     <code>num2*den1</code> products limb-by-limb fr