Do you guys have any sort of empirical evidence that scalar SSE2 math is
faster than plain old x87?

I ask because every time I tried compiling FFTW with gcc -m32
-mfpmath=sse, the result has been invariably slower than the vanilla x87
compilation.  (I am talking about scalar arithmetic here.  FFTW also
supports SSE2 2-way vector arithmetic, which is of course faster.)

I also remember trying similar experiments with other numerical code in
the Pentium 4 dark ages, with similar results.  I don't see any reason
why this should be the case, and maybe this is just a problem of gcc,
but I don't think you should automatically assume that SSE2 math is
faster without running a few experiments first.

Regards,
Matteo Frigo