Re: [eigen] Eigen SSE denorm modes?

[Mark Borgerding <mark@xxxxxxxxxxxxxx>]

On 03/08/2012 04:22 PM, Dick Lyon wrote:
> Is there a way to control how Eigen deals with denormalized floats?
> There are low-level SSE registers to control flushing to zero and such,
> but does anyone who how to control them, or what the defaults are?
>
> Dick

DAZ and FTZ makes a big speedup on intel machines, since handling 
denormals is really slow (and often only propagates rounding errors).

You can enabling these modes yourself:
    _mm_setcsr( _mm_getcsr() | (1<<15));  // FTZ
    _mm_setcsr( _mm_getcsr() | (1<<6)); // DAZ