supported. 

<p>
<code>--enable-3dnow</code> enables generic 3DNow! support using <code>gcc</code> builtin functions.  This works on earlier AMD
processors, but it is not as fast as our special assembly routines. 
As of fftw-3.1, --enable-3dnow is no longer supported. 

<h2><A name="fma">
Question 2.6.  What's the difference between the fma and the non-fma
versions?
</A></h2>

The fma version tries to exploit the fused multiply-add instructions
implemented in many processors such as PowerPC, ia-64, and MIPS