Greetings, and thanks for pointing this out. Actually, I maintain a few numerical packages requiring this flag on m68k to pass the regression tests in the package (gcl/maxima, atlas, blas, lapack,...). I suppose the sacrifice of performance is the correct approach. Anyone actually using the 68k with a different opinion will likely sway my mind in the other direction :). This would of course require sidestepping integrity tests in this case, as I won't have the time to maintain dual sets of expected results.
Take care, Steve Haflich <[EMAIL PROTECTED]> writes: > From: Camm Maguire <[EMAIL PROTECTED]> > > > -ffloat-store > > Do not store floating point variables in registers. > This pre- > > vents undesirable excess precision on machines such as the > 68000 > > where the floating registers (of the 68881) keep more > precision > > than a double is supposed to have. > > > > For most programs, the excess precision does only good, > but a > > few programs rely on the precise definition of IEEE > floating > > point. Use `-ffloat-store' for such programs. > > That did it -- thanks! As Richard Fateman observed, its quite > surprising the magnitude of the difference was so large. Apparently > m68k has the more accurate answer, right? In any case, I'm adding > -ffloat-store to gcl's compile flags on m68k to avoid testing > problems. > > But don't be misled -- the effect is not only precision. The 68881/2 > were admirably fast and capable chips for their day, but had a serious > bottleneck loading and storing floats. You may find that performance > is greatly reduced in some circumstances. > > Of course, anyone still using decade-old processor chips probably > doesn't consider speed the most important issue. > > -- Camm Maguire [EMAIL PROTECTED] ========================================================================== "The earth is but one country, and mankind its citizens." -- Baha'u'llah
