de>
     since then gcc knows it's "predicable".
<li> Itanium: GCC 3.4 introduces <code>__builtin_popcount</code> which can be
     used instead of an <code>asm</code> block.  The builtin should give gcc
     more opportunities for scheduling, bundling and predication.
     <code>__builtin_ctz</code> similarly (it just uses popcount as per
     current longlong.h).
<li> UltraSPARC/64: Optimize <code>mpn_mul_1</code>, <code>mpn_addmul_1</code>,
     for s2 &lt; 2^32 (or perhaps for any zero 16-bit s2 chunk).