7 Feb
2003
7 Feb
'03
4:10 p.m.
On Fri, Feb 07, 2003 at 02:16:08 +0100, David Olofson wrote:
On Friday 07 February 2003 10.55, Steve Harris wrote:
Its not a true cast, and the branch is cheaper than the denormal. Much
cheaper.
- Steve
On Thu, Feb 06, 2003 at 11:13:45 +0100, David
Olofson wrote:
Well, casting to int avoids getting the denormal into the FPU. This is
probably the only safe way to deal with a denormal without forcing
the FPU to burn cycles evaluating it. I don't see how this has
anything to do with the conditional, though. It's a potential
misprediction + pipeline flush regardless of whether the controlling
input comes from the FPU or the ALU. On Thursday 06 February 2003 16.28, Steve Harris
wrote:
[...]
Yes, but its not in a float context so it wont get
denormallised(?). #define FLUSH_TO_ZERO(fv) (((*(unsigned
int*)&(fv))&0x7f800000)==0)?0.0f:(fv) I think it came from the
music-dsp list.
There's a conditional in there, though.