On 6/2/14, Mark Kettenis <mark.kette...@xs4all.nl> wrote: >> Date: Mon, 2 Jun 2014 10:17:53 +0200 (CEST) >> From: Mark Kettenis <mark.kette...@xs4all.nl> >> >> > Date: Mon, 02 Jun 2014 09:34:20 +0200 >> > From: Benjamin Baier <program...@netzbasis.de> >> > >> > You might want to read up on floating point arithmetic. (rounding and >> > representation) >> >> Well, the difference between 4.994404 and 5.0 is a bit large to blame >> rounding and binary representation. And other OpenBSD platforms >> (amd64, sparc64, powerpc) return the expected result. So I'd say that >> there is a bug in the i386-specific implementation of exp2(3). > > And here is a fix. There actually isn't any i386-specific code, but > i386 is "special" and needs STRICT_ALIGN() to work properly for double > as well as float. FreeBSD made the same change a while ago: > > http://svnweb.FreeBSD.org/base/head/lib/msun/src/math_private.h?revision=240827&view=markup
You are quick. Thanks for figuring this out. Ugh ... "it was intentionally left broken as an optimization". That's crazy. OK martynas@. > Haven't run the regression tests yet with this change. > > > Index: src/math_private.h > =================================================================== > RCS file: /cvs/src/lib/libm/src/math_private.h,v > retrieving revision 1.16 > diff -u -p -r1.16 math_private.h > --- src/math_private.h 12 Nov 2013 20:35:09 -0000 1.16 > +++ src/math_private.h 2 Jun 2014 09:30:13 -0000 > @@ -349,7 +349,7 @@ do { > \ > #define STRICT_ASSIGN(type, lval, rval) do { \ > volatile type __lval; \ > \ > - if (sizeof(type) >= sizeof(double)) \ > + if (sizeof(type) >= sizeof(long double)) \ > (lval) = (rval); \ > else { \ > __lval = (rval); \ >