On Wednesday 03 March 2010 15:38:06 Chris Lattner wrote:> > Signalling NaN is one case. I'm sure there are others. > > The only other thing I could imagine that it is useful for is for rounding > mode control.Yep.> IMO rounding mode should be explicitly marked on the > instruction as well.That would also be useful for some GPUs where each instruction can specify its own rounding mode. -Dave
On Mar 3, 2010, at 1:53 PM, David Greene wrote:>> >> IMO rounding mode should be explicitly marked on the >> instruction as well. > > That would also be useful for some GPUs where each instruction can specify > its own rounding mode.SSE4 also has this for at least one conversion instruction. -Chris
On Mar 3, 2010, at 3:20 PM, Chris Lattner wrote:> > On Mar 3, 2010, at 1:53 PM, David Greene wrote: > >>> >>> IMO rounding mode should be explicitly marked on the >>> instruction as well. >> >> That would also be useful for some GPUs where each instruction can specify >> its own rounding mode. > > SSE4 also has this for at least one conversion instruction.As does ARM NEON. Sorta. vcvt normally uses round-to-zero, but it can optionally use the mode specified by the control register instead.