Enable FTZ/DAZ for SSE?

[H. J. Lu]

On Tue, Aug 09, 2005 at 01:35:11PM -0700, Richard Henderson wrote:
> On Tue, Aug 09, 2005 at 11:02:22AM -0700, H. J. Lu wrote:
> > I have a small testcase to show that enable FTZ/DAZ makes a huge (>160
> > times faster) difference on SSE floating point code. Icc enables it by
> > defailt for -ON (N>=1). Should gcc do the same?
> 
> This is the flush-denormals-to-zero bit?
> 

Yes, FTZ stands for flush to zero and DAZ stands for denormals are
zero.

> See config/{alpha,ia64,sparc}/crtfastmath.c, and how that gets used.
> 

The one for x86 may be very similar to alpha's crtfastmath.c. It can
be used for fast math on SSE targets.


H.J.