On Wed, Feb 18, 2004 at 01:20:30 +0100, Tim Blechmann wrote: > > I'm not up-to-date on benchmarks so I cant comment, but just to > > clarify the denormal thing in P4's is not a bug, its how you handle > > denormals, the only difference is that the P4 takes longer to handle > > them so you get away with it less often. > > > > Ideally DSP software would be written so that it never generates them, > > but, erm, well, developers are lazy, y'know :) > sure, denormals are not a bug, but the behaviour on dsp systems that > aren't denormal-save is similar to a bug ;-) > > > On the P4 its possible that you can set some flags to use SSE > > instructions instead of 387 and tell the SSE unit to never produce > > denormals, but last time I tried it, gcc 3.something generated bad > > code (illegal instructions). > wait ... you imply that the sse unit doesn't produce denormals, so that > a -march=sse _should_ solve all dsp user problems? > i heard that gcc 3.2 produces illegal instructions, but that it's solved > in gcc 3.3 ... can anyone confirm / deny this? SSE /can/ be prevented from producing denormals, it probably doesnt by default because it would violate the IEEE float spec. - Steve
