Date: Sat, 24 Aug 1996 18:22:55 +1000 From: Bruce Evans <bde@zeta.org.au> To: bde@zeta.org.au, gclarkii@main.gbdata.com Cc: freebsd-hackers@freefall.freebsd.org, kuku@gilberto.physik.rwth-aachen.de Subject: Re: max math performance - how? Message-ID: <199608240822.SAA20590@godzilla.zeta.org.au>
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>Maybe we should go back to libm as the default and tell people that if they >have either the GPL'ed MATH_EMU --OR-- a real math-co then they should >should compile libmsun with HAVE_FPU. No, msun is slower than libm (in the !HAVE_FPU case) because it is more correct. The only reason to keep libm is that msun doesn't work on machines that don't have IEEE floating point. I was wrong saying that msun is slower. Many parts are faster because they use optimizations that depend on IEEE format. I guess only things like sin() for large args are much slower (because they are more accurate). Users shouldn't have to manage libraries. >This brings up another joint subject. Does GCC still use a dumb version >of some math routines as default or has this changed? This changed in gcc-2.6.3 or earlier a long time ago. Bruce
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